thromboplastin and Hemorrhage

Tissue factor is the primary initiator of the coagulation cascade. Formation of the TF:FVIIa complex activates both FX and FIX, with subsequent thrombin generation, fibrin deposition and activation of platelets. In addition to playing important role in hemostasis and thrombosis, TF and downstream coagulation proteases can mediate intracellular signaling via activation of protease-activated receptors (PARs). Maintaining hemostasis in the brain is of utmost importance: bleeding or thrombosis within this organ can lead to significant morbidity and mortality. Both TF and PARs are widely expressed within the CNS, with TF expressed predominantly by astrocytes and PARs expressed in multiple cell types including astrocytes, neurons, microglia and oligodendrocytes [1-4]. PARs activation can result in either neuronal survival or death and link the coagulation system with the inflammatory response. In this brief review we summarize the contribution of the coagulation system to brain hemostasis as well as to the pathophysiology of stroke and multiple sclerosis.

Topics: Animals; Astrocytes; Autoimmunity; Blood Coagulation; Brain; Hemorrhage; Hemostasis; Humans; Inflammation; Multiple Sclerosis; Stroke; Thromboplastin

From acute coronary syndrome (ACS) to the prevention of cardioembolic events in patients with atrial fibrillation and thrombosis of mechanical heart valves, there is a quest to develop a new generation of anticoagulants. Perhaps the 'holy grail' of antithrombotic therapy is not only a drug that will prevent coagulation without promoting bleeding but also an anticoagulant that is easily reversible should the clinical need arise. Further, an optimally designed anticoagulant would have broad applications to include arterial, venous, hybrid conditions (atrial flutter and fibrillation) and nonbiological materials. Factor (F)IXa plays a pivotal part in tissue factor (TF)-mediated thrombin generation, and therefore represents a potentially promising target for drug development. FIXa activity has been targeted by multiple modalities, including oral inhibitors, RNA aptamers, monoclonal antibodies and synthetic active-site-blocking competitive inhibitors. Herein, we summarize the biochemistry of FIXa as it applies to thrombotic disorders and conditions, as well as the evolution of targeted therapies.

Topics: Acute Coronary Syndrome; Animals; Anticoagulants; Atrial Fibrillation; Drug Design; Factor IXa; Hemorrhage; Humans; Thrombin; Thromboplastin; Thrombosis

Anticoagulants are effective at preventing and treating thrombosis, but can cause bleeding. For decades, vitamin K antagonists (VKAs) have been the only available oral anticoagulants. The development of non-VKA oral anticoagulants (NOACs), which inhibit either factor Xa or thrombin stoichiometrically, has provided alternatives to VKAs for several indications. The results of recent large-scale randomised controlled trials comparing NOACs with VKAs for the prevention of stroke in patients with non-valvular atrial fibrillation (AF) have produced some unexpected results. As a group, NOACs showed similar efficacy as warfarin, but a reduced risk of major bleeding. The reduction in bleeding with NOACs was greatest with intracranial hemorrhage. In contrast, the relative risk of gastro-intestinal bleeding was increased with some NOACs. In this review, we explore the potential mechanisms as well as the implications of these organ-specific bleeding patterns.

Topics: Anticoagulants; Atrial Fibrillation; Blood Coagulation Factors; Endothelium, Vascular; Factor Xa Inhibitors; Gastrointestinal Hemorrhage; Hemorrhage; Humans; International Normalized Ratio; Intestinal Absorption; Intracranial Hemorrhages; Organ Specificity; Randomized Controlled Trials as Topic; Stroke; Thrombophilia; Thromboplastin; Vitamin K; Warfarin

The use of high intensity anticoagulation in the prevention of recurrence of arterial thrombosis related to the Antiphospholipid Syndrome (APS) is still controversial. This paper reports a debate that took place at the CORA meeting (Controversies in Rheumatology and Autoimmunity), held in Florence in March 2011. Major points of discussion were: 1) the paucity of prospective randomized clinical trials; retrospective studies were the main source supporting the use of high intensity anticoagulation; 2) heterogeneity in antiphospholipid antibodies (aPL) definition, due to the lack of standardization of aPL assays and to the failure to distinguish patients with a high risk profile ("triple positive") from those a low risk profile; 3) bleeding is a major concern about high intensity anticoagulation; however, studies are not concordant in reporting an increased risk compared to the standard regimen; 4) practical issues consist of difficulties in keeping a stable PT-INR over 3 and the possibility for interference by aPL on the thromboplastins used for PT-INR measurement. In conclusion, there is currently a lack of consensus on the use of high intensity anticoagulation for the secondary prophylaxis of arterial thrombosis. However, such a treatment may be particularly recommended in those APS patients who have a high risk aPL profile and other concomitant cardiovascular risk factors, provided that the potential benefit outweighs the risk of bleeding.

Topics: Animals; Antibodies, Antiphospholipid; Anticoagulants; Antiphospholipid Syndrome; Arteries; Clinical Protocols; Consensus Development Conferences as Topic; Hemorrhage; Humans; Practice Guidelines as Topic; Randomized Controlled Trials as Topic; Recurrence; Thromboplastin; Thrombosis

Hemostasis and thrombosis are now increasingly recognized as integrally related to blood rheology and blood flow. Platelets, for example, are known to access the vessel wall in ways which depend upon the small-scale motions of neighboring erythrocytes, and access one another via collisions driven by gradients in blood flow velocity. In this context, flow devices have become a subject of great interest in the clinical assessment of bleeding disorders, especially platelet function defects and von Willebrand disease. While these devices currently lack standardization and outcomes measures which establish clear clinical utility, their promise remains great, particularly in the potential to simulate the microenvironment of arteries vs. veins and in their ability to incorporate such intrinsically flow-dependent phenomena as co-localization of tissue-factor-bearing microparticles with platelets, the weakness of the GPIb-vWF bond at very high shear stresses, and even the hemostatic and antithrombotic function of vascular endothelium. In contrast, currently utilized assays are often performed under static conditions that do not involve flow and therefore are not able to simulate the microenvironment of arteries and veins.

Topics: Animals; Blood Flow Velocity; Blood Platelets; Blood Vessels; Cell-Derived Microparticles; Endothelium, Vascular; Erythrocytes; Hemorheology; Hemorrhage; Hemostasis; Humans; Membrane Glycoproteins; Platelet Glycoprotein GPIb-IX Complex; Thromboplastin; Thrombosis; von Willebrand Diseases; von Willebrand Factor

Acute promyelocytic leukemia (APL) has evolved from being a deadly to a highly curable disease, due to targeted molecular therapy with all-trans retinoic acid (ATRA). As a result, the incidence of early hemorrhagic deaths for which APL is notorious has reduced to 5-10% as reported in clinical trials. These results are not replicated outside of clinical trials as is evident from recent population-based registries. High incidence of early hemorrhagic deaths remains the greatest contributor to treatment failure in this otherwise curable leukemia. Additionally, thrombosis is now being increasingly recognized in APL patients and may be associated with ATRA usage.

Topics: Antifibrinolytic Agents; Antineoplastic Agents; Arsenic Trioxide; Arsenicals; Blood Coagulation Tests; Clinical Trials as Topic; Combined Modality Therapy; Cysteine Endopeptidases; Disseminated Intravascular Coagulation; Factor VIIa; Factor VIII; Fibrinogen; Fibrinolysis; Hemorrhage; Heparin; Humans; Leukemia, Promyelocytic, Acute; Multicenter Studies as Topic; Neoplasm Proteins; Oxides; Plasma; Platelet Count; Platelet Transfusion; Recombinant Proteins; Thromboplastin; Thrombosis; Treatment Failure; Tretinoin

We have been investigating the mechanism of blood coagulation and anticoagulation related to pathogenesis and the regulation of thrombosis and bleeding disorders. Since our focus is basically internal medicine and hematology, the contribution to this field is clinically based and aimed to help patients and maintain public health. In this review some of our achievements associated with the activation and regulation of blood coagulation are introduced, mainly based on our research with post-graduate medical technologists. The main topics are the structural and functional relationship of thrombomodulin (TM), the regulation of tissue factor (TF) and TM expression, TM gene therapy, activation of the extrinsic coagulation system due to increased TF-bearing leukocytes during and after cardiac surgery, endoplasmic reticulum-associated degradation of protein C and plasmin inhibitor mutants leading to protein deficiency, activation of blood coagulation with exposure of cellular or viral RNA, and the detection of novel bioactive peptides salusin-alpha and -beta.

Topics: Antifibrinolytic Agents; Blood Coagulation; Cardiac Surgical Procedures; Cholecalciferol; Endoplasmic Reticulum; Hemorrhage; Humans; Intercellular Signaling Peptides and Proteins; Leukocytes; Protein C; RNA, Viral; Thrombomodulin; Thromboplastin; Thrombosis; Tretinoin

Coagulation factor V (FV), present in plasma and platelets, is an indispensable clotting factor, as demonstrated by the uniform lethality of FV knock-out mice. Surprisingly, however, severe FV deficiency is rarely fatal in humans. In fact, although several cases of life-threatening intracranial haemorrhage have been reported in FV-deficient newborns, many patients with undetectable FV levels experience only mild to moderate bleeding and do not require routine prophylaxis. While the reasons for this variable phenotypic expression are largely unknown, several observations from different laboratories indicate platelets as crucial players in FV deficiency. Moreover, we have recently shown that plasma levels of tissue factor pathway inhibitor are considerably reduced in FV-deficient plasma, which results in enhanced thrombin generation especially at very low FV levels (<2%). The present review discusses and integrates these findings in the context of the biology of FV and the clinical features of FV deficiency.

Topics: Blood Coagulation; Blood Platelets; Factor V; Factor V Deficiency; Hemorrhage; Humans; Infant, Newborn; Lipoproteins; Thrombin; Thromboplastin

The research aims of our laboratory are to provide a realistic description of biologic processes involved in protection from hemorrhage and the evolution of thrombosis. To evaluate these processes, we use 4 models of coagulation ranging from 1) studies of blood exiting from microvascular wounds in humans through 2) minimally altered whole blood induced to clot by tissue factor (TF) to 3) reconstitution of the blood coagulation proteome with purified components and to 4) mathematical descriptions of the chemical processes and dynamics that occur. The integration of these 4 models permits comprehensive analyses of the blood coagulation system and predictions of its behavior under normal and pathologic conditions. Data accumulated thus far have led to advances in our understanding of 1) the processes occurring during the initiation and propagation phases of thrombin generation, 2) the roles for individual proteins involved in blood coagulation and its regulation, 3) defects in thrombin generation and clot formation in hemophilia, 4) actions and limitations of pharmacologic agents used to control hemorrhage, thrombosis, and chronic cardiovascular disease, and 5) the relationship between genotypic and phenotypic features of an individual's plasma proteome and his/her immediate and long-term thrombotic risk.

Topics: Blood Coagulation; Hemorrhage; Humans; Thromboplastin; Thrombosis

Severely septic patients continue to experience excessive morbidity and mortality despite recent advances in critical care. Although significant resources have been invested in new treatments, almost all have failed to improve outcomes. An improved understanding of sepsis pathophysiology, including the complex interactions between inflammatory, coagulation, and fibrinolytic systems, has accelerated the development of novel treatments. Recombinant human activated protein C (rhAPC), or drotrecogin alfa (activated) (DAA), is currently the only US Food and Drug Administration (FDA)-approved medicine for the treatment of severe sepsis, and only in patients with a high risk of death. This review will discuss the treatment of severe sepsis, focusing on recent discoveries and unresolved questions about DAA's optimal use. Increasing pharmacological experience has generated enthusiasm for investigating medicines already approved for other indications as treatments for severe sepsis. Replacement doses of hydrocortisone and vasopressin may reduce mortality and improve hypotension, respectively, in a subgroup of patients with catecholamine-refractory septic shock. In addition to discussing these new indications, this review will detail the provocative preliminary data from four promising treatments, including two novel modalities: antagonizing high mobility group box protein and inhibiting tissue factor (TF). Observational data from the uncontrolled administration of heparin or statins in septic patients will also be reviewed.

Topics: Adrenal Cortex Hormones; Anti-Infective Agents; Anti-Inflammatory Agents; Anticoagulants; Antidiuretic Agents; Drug Administration Schedule; Drug Therapy; Hemorrhage; Heparin; HMGB1 Protein; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Patient Selection; Protein C; Recombinant Proteins; Sepsis; Severity of Illness Index; Thromboplastin; Treatment Outcome; Vasopressins

Topics: Anticoagulants; Blood Coagulation; Blood Coagulation Factors; Blood Proteins; Hemorrhage; Humans; International Normalized Ratio; Prothrombin Time; Thrombin; Thromboplastin; Vitamin K; Warfarin

Tissue factor (TF) is best known as the primary cellular initiator of blood coagulation. After vessel injury, the TF:FVIIa complex activates the coagulation protease cascade, which leads to fibrin deposition and activation of platelets. TF deficiency causes embryonic lethality in the mouse and there have been no reports of TF deficiency in humans. These results indicate that TF is essential for life, most likely because of its central role in hemostasis. In addition, aberrant TF expression within the vasculature initiates life-threatening thrombosis in various diseases, such as sepsis, atherosclerosis, and cancer. Finally, recent studies have revealed a nonhemostatic role of TF in the generation of coagulation proteases and subsequent activation of protease activated receptors (PARs) on vascular cells. This TF-dependent signaling contributes to a variety of biological processes, including inflammation, angiogenesis, metastasis, and cell migration. This review focuses on the roles of TF in hemostasis, thrombosis, and vascular development.

Topics: Animals; Blood Coagulation Factors; Blood Vessels; Coronary Vessels; Female; Fetal Death; Hemorrhage; Hemostasis; Humans; Mice; Mice, Knockout; Myocytes, Cardiac; Phenotype; Placenta; Postpartum Hemorrhage; Pregnancy; Pregnancy Complications, Hematologic; Thromboplastin; Thrombosis; Uterus; Yolk Sac

Hemostasis governs two essential processes of human life in that it maintains the fluidity of blood under physiological conditions and prevents excessive blood loss after injury. Hemostasis is regulated by components of the vessel wall and blood cells and by humoral coagulation factors. Under normal conditions, these components are involved in an active equilibrium through activation, propagation, and termination of the hemostatic pathways. This equilibrium is disturbed upon vascular injury, leading to a procoagulant response when needed. Unfortunately, pathological disturbances can occur as a result of inherited or acquired coagulation factor deficiencies that may lead to bleeding or thrombotic disorders.

Topics: Anticoagulants; Hemorrhage; Hemostasis; Humans; Thrombin; Thromboplastin; Thrombosis

Exposure of blood to tissue factor (TF) sets off the coagulation cascade. TF is a transmembrane protein that serves as an essential cofactor for activated coagulation factor VII (FVIIa). TF may be exposed locally by vascular injury (such as balloon angioplasty) or by spontaneous rupture of an atherosclerotic plaque. Expression of TF may also be induced on monocytes and endothelial cells in conditions like sepsis and cancer, causing a more generalised activation of clotting. TF may thus play a central role in thrombosis in a number of settings, and attention has turned to blocking TF as a means to prevent thrombosis. Inhibiting the inducible expression of TF by monocytes can be achieved by 'deactivating' cytokines, such as interleukin (IL)-4, -10 and -13, or by certain prostanoids; by drugs that modify signal transduction, such as pentoxifylline, retinoic acid or vitamin D(3), or by antisense oligonucleotides. Such approaches are for the most part at a preclinical stage. The function of TF can be blocked by antibodies that prevent the binding of FVIIa to TF; by active site-inhibited FVIIa, which competes with native FVIIa for binding; by antibodies or small molecules that block the function of the TF/FVIIa complex; and by molecules, such as TF pathway inhibitor or nematode anticoagulant peptide C2, which inhibit the active site of FVIIa in the TF/FVIIa complex after first binding to activated factor X. The latter two agents have entered Phase II clinical trials. Perhaps most intriguing is the use of anti-TF agents locally, which holds the promise of stopping thrombosis at a specific site of injury without the bleeding risk associated with systemic anticoagulation.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Antibodies, Monoclonal; Arteriosclerosis; Blood Coagulation; Clinical Trials as Topic; Cytokines; Drug Design; Endothelium, Vascular; Enzyme Activation; Factor VIIa; Fibrinolytic Agents; Glycoproteins; Helminth Proteins; Hemorrhage; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Lipoproteins; Mice; Monocytes; Multiprotein Complexes; Neoplasms; Oligonucleotides, Antisense; Prostaglandins; Signal Transduction; Swine; Swine, Miniature; Thrombophilia; Thromboplastin; Thrombosis

Topics: Amino Acid Sequence; Animals; Blood Coagulation Factors; Enzyme Activation; Hemorrhage; Humans; Lipoproteins; Molecular Sequence Data; Protein Structure, Tertiary; Rabbits; Thromboplastin

Management of patients with factor VIII (and IX) inhibitors includes management of acute bleeds and methods to induce immune suppression and tolerance and to detect patients at risk of developing inhibitors. The methods used over the years to treat acute bleeding have been more or less successful. The best method is to raise factor VIII levels by human or porcine factor VIII concentrate, but this is not usually possible. Prothrombin complex concentrates, activated or non-activated, have enjoyed some success as factor VIII by passing agents, but the development of recombinant activated factor VII represents a new and promising method of inducing haemoslasis at the site of bleeding whilst minimizing the risk of disseminated intravascular coagulation. Alternatively, the use of tissue factor is under consideration to exploit the extrinsic system. Methods to induce immunological tolerance by use of the 'Bonn' regime or by the introduction of immunomodulation with the 'Malmö' regime of extracorporeal immunodepletion, cyclophosphamide, and intravenous immunoglobulin continue to be attempted with significant but variable success. Gradually the inhibitor problem is being contained, but it is still an important complication of haemophilia therapy.

Topics: Animals; Antifibrinolytic Agents; Blood Coagulation Factors; Combined Modality Therapy; Factor IX; Factor VIIa; Factor VIII; Hemophilia A; Hemophilia B; Hemorrhage; Humans; Immune Tolerance; Immunosuppressive Agents; Isoantibodies; Swine; Thromboplastin

Topics: Autoantibodies; Autoimmune Diseases; Blood Coagulation Factors; Blood Coagulation Tests; Collagen Diseases; Drug Hypersensitivity; False Positive Reactions; Female; Hemorrhage; Humans; Immunoglobulin M; Lupus Coagulation Inhibitor; Lupus Erythematosus, Systemic; Male; Neoplasms; Pregnancy; Pregnancy Complications, Hematologic; Thromboplastin; Thrombosis

Topics: Administration, Oral; Anticoagulants; Calcium; Drug Interactions; Hemorrhage; Humans; Partial Thromboplastin Time; Prothrombin; Prothrombin Time; Thromboplastin; Vitamin K

Disseminated intravascular coagulation (DIC) of blood develops as a result of a sharp increase in the release of thromboplastic substances. The mechanism of disseminated thrombosis is switched in at the level of the microcirculatory bed with defibrination of the peripheral blood and subsequent hemorrhages and bleedings. The causes of DIC development may include complications of pregnancy and delivery, different kinds of shock including endotoxin shock, hemorrhage, hemolysis. Histomorphological findings in DIC are as follows: hemorrhagic syndrome, fibrin thrombi in capillaries, arterioles and venules of the skin, kidneys, adrenals, hypophysis, gastrointestinal tract, lungs and other organs followed by necroses and hemorrhages in these organs. Clinically, DIC is manifested by symptoms of insufficiency of the affected organs (acute renal insufficiency, Waterhouse-Fridericksen syndrome, etc).

Topics: Disseminated Intravascular Coagulation; Female; Hemolysis; Hemorrhage; Humans; Kidney; Male; Microcirculation; Necrosis; Obstetric Labor Complications; Pregnancy; Pregnancy Complications, Hematologic; Shock; Surgical Procedures, Operative; Thromboplastin; Thrombosis

Topics: Blood Coagulation; Fibrin; Fibrinogen; Fibrinolysis; Hemorrhage; Heparin; Humans; Neoplasm Metastasis; Neoplasms; Thromboplastin; Thrombosis

Topics: Adult; Child; Ecchymosis; Epistaxis; Factor V; Factor V Deficiency; Female; Gastrointestinal Hemorrhage; Hemarthrosis; Hematuria; Hemorrhage; Humans; Hypoprothrombinemias; Male; Menstruation Disturbances; Prothrombin Time; Thromboplastin

Topics: Aminocaproates; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Coagulation Tests; Blood Transfusion; Factor V Deficiency; Factor VII Deficiency; Factor VIII; Fibrinogen; Freezing; Hemophilia A; Hemophilia B; Hemorrhage; Hemostasis; Humans; Hypoprothrombinemias; Plasma; Plasma Volume; Prothrombin; Prothrombin Time; Thromboplastin; Vitamin K

Topics: Adrenal Glands; Adrenocorticotropic Hormone; Animals; Antigen-Antibody Reactions; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Coagulation Tests; Catecholamines; Dibenzylchlorethamine; Endotoxins; Female; Fibrinolysis; Haplorhini; Hemolysis; Hemorrhage; Humans; Kidney; Microscopy, Electron; Mononuclear Phagocyte System; Necrosis; Phagocytosis; Phenoxybenzamine; Pregnancy; Pregnancy, Animal; Shock, Septic; Shwartzman Phenomenon; Thromboplastin

Topics: Abruptio Placentae; Adrenal Glands; Aminocaproates; Animals; Basement Membrane; Biopsy; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Platelets; Brain; Female; Fibrin; Fibrinogen; Fibrinolysis; Fluorescent Antibody Technique; Hemorrhage; Hemorrhagic Disorders; Heparin; Humans; Hypertension, Malignant; Kidney Cortex Necrosis; Kidney Failure, Chronic; Kidney Glomerulus; Liver; Maternal Mortality; Microscopy, Electron; Myocardium; Placental Extracts; Pre-Eclampsia; Pregnancy; Rabbits; Shwartzman Phenomenon; Thromboplastin; Thrombosis

Topics: Anticoagulants; Blood Cell Count; Blood Coagulation Tests; Blood Platelets; Diagnosis, Differential; Fibrin; Fibrinogen; Hemorrhage; Hemorrhagic Disorders; Humans; Prothrombin; Prothrombin Time; Thromboplastin; Vascular Resistance

Topics: Blood Coagulation Factors; Blood Coagulation Tests; Blood Transfusion; Cerebral Hemorrhage; Epistaxis; Factor VIII; Gastrointestinal Hemorrhage; Hemarthrosis; Hematuria; Hemophilia A; Hemorrhage; Humans; Oral Hemorrhage; Thromboplastin; Wounds and Injuries

Thrombo-inflammation is central to COVID-19-associated coagulopathy. TF (tissue factor), a driver of disordered coagulation and inflammation in viral infections, may be a therapeutic target in COVID-19. The safety and efficacy of the novel TF inhibitor rNAPc2 (recombinant nematode anticoagulation protein c2) in COVID-19 are unknown.. ASPEN-COVID-19 was an international, randomized, open-label, active comparator clinical trial with blinded end point adjudication. Hospitalized patients with COVID-19 and elevated D-dimer levels were randomized 1:1:2 to lower or higher dose rNAPc2 on days 1, 3, and 5 followed by heparin on day 8 or to heparin per local standard of care. In comparisons of the pooled rNAPc2 versus heparin groups, the primary safety end point was major or nonmajor clinically relevant International Society of Thrombosis and Haemostasis bleeding through day 8. The primary efficacy end point was proportional change in D-dimer concentration from baseline to day 8, or discharge if before day 8. Patients were followed for 30 days.. rNAPc2 treatment in hospitalized patients with COVID-19 was well tolerated without excess bleeding or serious adverse events but did not significantly reduce D-dimer more than heparin at day 8.. URL: https://www.. gov; Unique identifier: NCT04655586.

Topics: Anticoagulants; Antifibrinolytic Agents; Blood Coagulation Disorders; COVID-19; Female; Fibrin Fibrinogen Degradation Products; Hemorrhage; Heparin; Humans; Inflammation; Male; Middle Aged; Thromboplastin; Venous Thromboembolism

Acute promyelocytic leukemia (APL) cells constitutively express a large amount of tissue factor (TF) antigen, most of which is present in the cytoplasm. Coagulopathy may persist after induction therapy. We evaluated the overall role of circulating microparticles (MPs) in coagulation activation in APL-associated coagulopathy before and during induction therapy. Eleven adult patients with ≥ World Health Organization's (WHO) grade 2 bleeding events and 11 sex- and age-matched healthy controls were selected. All patients received arsenic trioxide alone as induction therapy. MP-associated TF (MP-TF) activity and MP procoagulant activity (MP-PCA) and 12 coagulation- and anticoagulation-associated indexes were measured before, during, and after induction therapy. Correlation between MP-associated indexes and the other 12 indexes was analyzed in patients. The MP-TF activity was negligible in controls, whereas it markedly increased in patients, dropped rapidly after treatment, and returned to normal at the end of induction therapy. The MP-PCA was similar between patients and controls. The correlation analysis revealed that TF-bearing MPs in patients mainly originated from APL cells. Partially differentiated APL cells could also release TF-bearing MPs, and the higher the degree of APL cell differentiation, the lower the ability of APL cells to release TF-bearing MPs. MP-TF was the main source of active TF in plasma and an important contributor for the coagulation activation in APL-associated coagulopathy. It was MPs released by APL cells/partially differentiated APL cells that served as the vehicle to transfer the large amount of TF to plasma to activate coagulation.

Topics: Adult; Antineoplastic Agents; Arsenic Trioxide; Blood Coagulation; Cell-Derived Microparticles; Female; Hemorrhage; Humans; Leukemia, Promyelocytic, Acute; Male; Middle Aged; Prospective Studies; Thromboplastin

Exposure of tissue factor (TF) is a critical proximal step in the pathogenesis of acute coronary syndromes. Sunol-cH36, a chimaeric monoclonal antibody to TF, blocks binding of factor X to the TF:VIIa complex. This report describes the first completed trial of Sunol-cH36 in humans.. We assessed the safety and pharmacokinetics of Sunol-cH36 in an open-label, dose-escalating trial among subjects with stable coronary artery disease. The safety analysis included all adverse events with a focus on overt or occult bleeding. Five doses of Sunol-cH36 (0.03, 0.06, 0.08, 0.1, 0.3 mg/kg) were administered as a single intravenous bolus to 26 subjects (three to eight subjects per dose tier). No major bleeding (> or =2 g/dL haemoglobin decline) occurred. Spontaneous minor bleeding was observed with a dose-related pattern. Notably, the majority of spontaneous bleeding episodes were clinically consistent with platelet-mediated bleeding (e.g. gum, tongue) without thrombocytopenia. The median terminal half-life was 72.2 (25th, 75th: 28.4, 72.5) h.. Sunol-cH36 exhibited dose-dependent anticoagulant effects. We postulate that the mucosal bleeding observed with this potent inhibitor of thrombin generation may reflect antiplatelet effects resulting from networking between the coagulation cascade and platelet pathways that could prove clinically relevant with this novel class of anticoagulants.

Topics: Adult; Aged; Antibodies, Monoclonal; Aspirin; Blood Coagulation; Cohort Studies; Coronary Artery Disease; Dose-Response Relationship, Drug; Female; Half-Life; Hemorrhage; Humans; Injections, Intravenous; Male; Middle Aged; Platelet Aggregation Inhibitors; Thrombin; Thromboplastin

A different rate and timing of subacute stent thrombosis after percutaneous coronary intervention was reported with various peri-interventional antithrombotic regimens. Next to platelet activation, coagulation triggered by tissue factor (TF) may play a key role in this process. Thirty-one consecutive patients with stable and unstable angina undergoing coronary stenting were randomly assigned to adjunct oral anticoagulation/anti-platelet therapy (coumadin, dipyridamole, aspirin and heparin; n = 16) or adjunct anti-platelet therapy with thienopyridin (ticlopidine, aspirin and heparin; n = 15). Antigen levels of plasma TF, total tissue factor pathway inhibitor (TFPI) and TFPI/ activated factor X (TFPI/FXa) complex were determined before and for up to 6 days after intervention by immunoassay. At baseline, significantly higher levels of plasma TF and TFPI/FXa were found in patients with unstable angina [TF, 161 pg/ml (126-191 pg/ml); TFPI/FXa, 7.8 ng/ml (6.1-9.6 ng/ml)] compared with stable angina [TF, 62 pg/ml (46-82 pg/ml), P < 0.0001; TFPI/FXa, 4.5 ng/ml (3-7.6 ng/ml), P= 0.003]. One hour after intervention, an increase of plasma TF and TFPI/FXa was seen in both treatment groups. In unstable angina patients, plasma levels of TF, TFPI and TFPI/FXa were more efficiently reduced by adjunct ticlopidine therapy compared with adjunct coumadin/dipyridamole. These data suggest reduced release of circulating TF by combined anti-platelet therapy with ticlopidine and aspirin after coronary artery stenting, which may-contribute to the lower incidence of subacute stent thrombosis previously observed.

Topics: Adult; Angina Pectoris; Angina, Unstable; Angioplasty, Balloon, Coronary; Anticoagulants; Aspirin; Coronary Angiography; Coronary Stenosis; Dipyridamole; Dose-Response Relationship, Drug; Drug Therapy, Combination; Enzyme-Linked Immunosorbent Assay; Factor Xa; Female; Follow-Up Studies; Hemorrhage; Heparin; Humans; Lipoproteins; Male; Middle Aged; Statistics as Topic; Stents; Thromboplastin; Thrombosis; Ticlopidine; Time Factors; Warfarin

Abciximab, a nonselective glycoprotein IIb/IIIa inhibitor, was shown to reduce peri-interventional stroke rate in carotid stenting. We evaluated the effect of adjunct abciximab therapy on monocyte-platelet cross talk and neurological deficit in unprotected carotid stenting and compared its efficacy with distal filter protection.. Fifty patients were randomized to either standard antithrombotic therapy (n=30) consisting of aspirin, clopidogrel, and heparin or adjunct bolus (0.25 mg/kg) and 12-hour infusion (0.125 microg x kg(-1) x min(-1)) of abciximab (n=20). A third cohort of patients was stented with filter protection (n=30). Monocyte-platelet aggregate formation and monocyte tissue factor expression were determined by whole blood flow cytometry, and F1.2 generation and soluble CD40 ligand (sCD40L) were determined by immunoassay.. The incidence of peri-interventional ischemic episodes (23% versus 10%; P=0.2) and the number of de novo ischemic lesions detected by diffusion-weighted MRI (47% versus 30%; P=0.17) were not significantly different between standard antithrombotic therapy and adjunct abciximab but were reduced with filter protection (P=0.023). However, the number of transient ischemic attacks was lower (P=0.05) and the National Institutes of Health Stroke Score rapidly decreased in patients with adjunct abciximab. This clinical improvement was paralleled by a reduction in the postinterventional percentage of activated monocyte-platelet aggregates (CD62P+/CD14+; P=0.018) and the number of tissue factor-positive monocytes (TF+/CD14+; P=0.005). Both abciximab and filter protection suppressed F1.2 generation and significantly reduced sCD40L.. Abciximab limits thrombus propagation and thrombus stabilization after carotid stenting by reducing monocyte-platelet cross talk and sCD40L. Although abciximab seems inferior to filter devices in peri-interventional cerebral protection, it may be considered in patients who do not allow placement of protection devices.

Topics: Abciximab; Aged; Angioplasty; Antibodies, Monoclonal; Anticoagulants; Blood Vessel Prosthesis Implantation; Brain Ischemia; Carotid Stenosis; Cell Aggregation; Chemotherapy, Adjuvant; Cohort Studies; Female; Fibrinolytic Agents; Filtration; Hemorrhage; Humans; Immunoglobulin Fab Fragments; Ischemic Attack, Transient; Male; Monocytes; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Stents; Thromboplastin; Treatment Outcome

With the best prophylactics now available, venous thromboembolism after total knee replacement remains substantial (25% to 27%). Recombinant nematode anticoagulant protein c2 (rNAPc2) is a potent inhibitor of factor VIIa/tissue factor complex that has the potential to reduce this risk. The present study was performed to determine an efficacious and safe dose of rNAPc2 for prevention of venous thromboembolism after elective, unilateral total knee replacement.. This open-label, sequential dose-ranging study was conducted in 11 centers in Canada, Europe, and the United States. Five regimens were tested. Injections were administered subcutaneously on the day of surgery (day 1) and days 3, 5, and optionally, day 7. Primary efficacy outcome was a composite of overall deep vein thrombosis based on mandatory unilateral venography (day 7+/-2) and confirmed symptomatic venous thromboembolism recorded

Topics: Aged; Anticoagulants; Arthroplasty, Replacement, Knee; Canada; Dose-Response Relationship, Drug; Europe; Factor VIIa; Female; Helminth Proteins; Hemorrhage; Humans; Injections, Subcutaneous; Logistic Models; Male; Odds Ratio; Postoperative Complications; Risk Assessment; Survival Rate; Thromboplastin; United States; Venous Thrombosis

Monitoring patients on oral anticoagulation is essential to prevent hemorrhage and recurrent thrombosis. We studied tissue factor-induced whole-blood coagulation in patients on warfarin therapy with similar international normalized ratios (INRs).. Contact pathway-suppressed whole-blood coagulation initiated with tissue factor was studied in 8 male subjects (group W) and in 1 individual multiple times (subject A). Coagulation profiles for group W showed that subjects with similar INRs had widely varying clot times (6.2 to 23 minutes) and thrombin-antithrombin III (TAT) profiles with rates of 25 to 40 nmol. L(-1). min(-1) and maximum levels varying from 192 to 349 nmol/L. The normal control group exhibited clot times of 5.7+/-0.3 minutes and TAT rates of 57+/-13 nmol. L(-1). min(-1), reaching maximum levels of 742+/-91 nmol/L. Subject A, who was stably anticoagulated at an INR of 2.1+/-0.4 for 6 months, had widely ranging profiles with clot times of 9.0 to 22.7 minutes, TAT maximums varying from 141 to 345 nmol/L, and TAT formation rates of 10 to 57 nmol. L(-1). min(-1). INR did not correlate with TAT formation. Platelet activation was decreased by anticoagulants but also displayed variability. Fibrinopeptide A generation showed threshold variability independent of the INR. Factor VIII levels were increased (P=0.03) in group W (204+/-34.4%) compared with normal control subjects (149.4+/-37.4%). A significant correlation was identified between increasing factor VIII levels and years on warfarin therapy (r=0.78, P=0.01), suggesting a possible factor VIII compensatory mechanism.. These results suggest that control of anticoagulation in patients to a set INR therapeutic range may be less secure than anticipated. Patients with similar INRs show significant individual variability in their tissue factor coagulation response, suggesting different risks to anticoagulation when confronted with underlying vascular anomalies.

Topics: Administration, Oral; Aged; Anticoagulants; Blood Coagulation; Blood Coagulation Tests; Dose-Response Relationship, Drug; Drug Monitoring; Hemorrhage; Humans; International Normalized Ratio; Male; Middle Aged; Reference Values; Thromboplastin; Thrombosis; Warfarin; Whole Blood Coagulation Time

Abnormal uterine bleeding after Norplant administration is primarily responsible for the high discontinuation rate of this safe and effective long-acting implantable progestin-only contraceptive agent. Although tissue factor (TF) is the primary initiator of hemostasis, previous studies indicated that Norplant-associated bleeding persists despite relatively high TF levels in the stromal compartment. Recently, we determined that progestin-enhanced TF expression during decidualization of human endometrial stromal cells involves both the epidermal growth factor receptor and progesterone receptor (PR]. The current study evaluated TF levels in endometrial bleeding (BL) and nonbleeding (NBL) sites obtained by camera-guided hysteroscopy during Norplant contraception. After 1 yr of therapy, immunohistochemical TF levels were unexpectedly higher at BL than at NBL sites. Use of immunohistochemistry and Western blotting indicated that both sites displayed elevated epidermal growth factor receptor levels and that the BL sites exhibited high levels of the PR, as well as the PR(A) and the PR(B) isoforms. Microscopic examination of 1-yr biopsies revealed that significantly larger numbers of enlarged, distended vessels were present in BL, compared with NBL sites. Elevated TF levels and abnormally enlarged blood vessels in the BL sites are consistent with the recently discovered angiogenic role of TF. By promoting aberrant angiogenesis, chronic endometrial overexpression of TF could produce fragile vessels, which are at increased risk to bleed. Analysis of endometrial BL and NBL sites, during Norplant contraception, offers the potential of elucidating local mechanisms that control enhanced TF expression, leading to abnormal angiogenesis at specific endometrial sites.

Topics: Adult; Blood Vessels; Blotting, Western; Contraceptive Agents, Female; Endometrium; Female; Hemorrhage; Humans; Immunohistochemistry; Levonorgestrel; Receptors, Progesterone; Thromboplastin

Various methods have been described to evaluate efficacy of anticoagulant therapy using the international normalized ratio (INR). We compared the following approaches: (1) total INR's or the most recent measurement; (2) percent time within therapeutic range, with INR changing directly or halfway between visits; and (3) total observation time assuming INR changing linearly. The study population comprised 1700 post myocardial infarction patients. Treatment comprised 3725 patient-years. There were 61,471 INR assessments with target therapeutic level of 2.8-4.8. Acenocoumarol as well as phenprocoumon were employed. Therapeutic achievement in the first months of treatment was low: less than 60% of INR's were in range. Treatment stabilized after 6 months. Patients on acenocoumarol were within range 70% of the time compared to 80% for phenprocoumon. Method 3 is preferred because it incorporates time and is capable of calculating incidence rates at different INR levels. Our findings call for an urgent improvement of standard of anticoagulant control in the first months following commencement of treatment.

Topics: Acenocoumarol; Aged; Anticoagulants; Cardiovascular Diseases; Convalescence; Double-Blind Method; Female; Follow-Up Studies; Hemorrhage; Humans; Male; Middle Aged; Myocardial Infarction; Phenprocoumon; Prothrombin Time; Quality Control; Reference Standards; Thromboplastin; Treatment Outcome

A total of 1290 patients (Pts) undergoing general surgery were enrolled in a randomized, multicentre double-blind study in order to investigate the efficacy and safety of two different doses of a low molecular weight heparin (LMWH) (Logiparin) for the prevention of deep vein thrombosis. Patients were randomized to either 5,000 IU unfractionated heparin twice daily, 2,500 anti-Xa or 3,500 anti-Xa units of Logiparin once daily. Each treatment was given subcutaneously two hours before surgery and continued for seven to ten days. All coagulation tests were performed blindly in a core laboratory. Blood samples were collected before surgery and then 3 hours after injection on Day 3 and 5 after surgery. Anti-Xa amidolytic activities were significantly higher in the two LMW Heparin groups than in the unfractionated heparin group (mean peak levels +/- s.e.m. on Day 3: 0.097 +/- 0.004; 0.152 +/- 0.004 and 0.034 +/- 0.003 IU respectively). As expected a significant correlation was observed between anti-Xa activity and the dose of LMW Heparin injected. The correlation coefficient was higher when the doses were expressed in anti-Xa units/kg body weight. However, the body weight accounts for only 16% of the interindividual variability of anti-Xa activity. Therefore, there is no clear evidence to suggest that weight-adjusted doses should be recommended when this LMW Heparin is used as prophylactic treatment in general surgery. A weak negative correlation was found between anti-Xa activity and thrombosis as demonstrated by a positive radiolabelled fibrinogen uptake test and confirmed by positive phlebography. No significant correlation was demonstrated between anti-Xa activity and the occurrence of postoperative bleeding.

Topics: Body Weight; Double-Blind Method; Drug Administration Schedule; Factor VII; Factor Xa Inhibitors; Female; Hemorrhage; Heparin; Heparin, Low-Molecular-Weight; Humans; Lipoproteins; Male; Postoperative Period; Thromboplastin; Thrombosis

A prospective open study was performed in a series of 547 patients undergoing gynecologic surgery. A dose of 20 mg of enoxaparin was administered to all patients 2 hours before surgery. Then patients at high risk of thrombosis (mostly oncologic surgery) received 40 mg of enoxaparin daily whereas those at moderate risk received 20 mg of enoxaparin daily. The principal aim of this prospective open study was to monitor amidolytic anti Xa activity and to study the inhibition of intrinsic prothrombinase using prothrombin consumption measurement as a simple and global test. A second aim was to investigate efficacy and tolerance of these regimens. Treatment tolerance was satisfactory with both regimens since the total incidence of bleeding was 1.8%. A single patient developed a clinically significant thrombosis during hospital stay. The results confirm and extend previous reports regarding a dose effect relationship between the dose of Enoxaparin and plasma Anti Xa activity 3 hours after s.c. injection. A significant relationship was found between Anti Xa activity and patients body weight. Interestingly a dose dependent inhibition of intrinsic prothrombinase was observed when using a one stage prothrombin consumption assay in whole blood. This test in whole blood can be considered as closer to physiological conditions than assays performed in citrated platelet rich or platelet poor plasma samples. The mechanism of intrinsic prothrombinase inhibition during prophylactic treatment with enoxaparin requires further investigation.

Topics: Adult; Body Weight; Dose-Response Relationship, Drug; Factor Xa Inhibitors; Female; Genital Diseases, Female; Hemorrhage; Heparin, Low-Molecular-Weight; Humans; Injections, Subcutaneous; Middle Aged; Partial Thromboplastin Time; Postoperative Complications; Prospective Studies; Prothrombin; Risk Factors; Thromboembolism; Thromboplastin

The British comparative thromboplastin (BCT) was used to monitor the effectiveness of oral anticoagulants in preventing deep vein thrombosis (DVT) in patients undergoing major gynaecological surgery. All patients were screened for DVT with the use of the (125)I-fibrinogen scan.One hundred and forty-five patients aged 40 years or more were randomised into three groups. Group 1 received oral anticoagulant (nicoumalone) treatment, stabilised over five days before surgery and continuing into the second postoperative week. The other patients served as two contrast groups and were managed on a double-blind basis. Group 2 received a subcutaneous low-dose regimen of heparin calcium. Group 3 received subcutaneous saline. Eleven of 48 patients in the saline group, three of 49 patients in the heparin group, and three of 48 patients in the oral anticoagulant group developed DVT as judged by (125)I-fibrinogen scanning. The incidences in groups 1 and 2 were significantly lower than in the saline group. The falls in haemoglobin concentration and incidence of haemorrhage were similar in all three groups.The study showed that oral anticoagulant prophylaxis stabilised preoperatively and low-dose heparin were equally effective in preventing deep vein thrombosis in a moderate-risk group. Immediate preoperative prothrombin ratios of 2.0-2.5 and postoperative ratios of 2.0-4.0 with the BCT gave adequate protection without increased haemorrhagic risk.

Topics: Acenocoumarol; Administration, Oral; Adult; Clinical Trials as Topic; Double-Blind Method; Female; Genitalia, Female; Hemoglobins; Hemorrhage; Heparin; Humans; Middle Aged; Thrombophlebitis; Thromboplastin

Among 100 consecutive patients receiving heparin in therapeutic dosage, major bleeding occurred in 21, and minor bleeding in 16. Two patients died from bleeding, and two had recurrent pulmonary embolism. Major bleeding occurred in 21% when therapy was regulated with whole-blood clotting time and in 20% when heparin was given without clotting tests. In a subsequent prospective trial patients received heparin by intermittent intravenous injection with or without laboratory control according to the partial thromboplastin time or continuously by intravenous infusion. Recurrent thromboembolism occurred once in each group. Major bleeding was seven times more frequent with intermittent injection than with continuous infusion. Control with the partial thromboplastin time did not prevent major bleeding in patients receiving intermittent injections. With continuous infusion, one-fourth less heparin was required than with intermittent injections. Administration of heparin by continuous infusion appears safer than intermittent injection with or without laboratory control and is no less effective for prevention of thromboembolism.

Topics: Administration, Oral; Adolescent; Adult; Aged; Arterial Occlusive Diseases; Blood Coagulation Tests; Cerebrovascular Disorders; Clinical Trials as Topic; Hemorrhage; Heparin; Humans; Infusions, Parenteral; Injections, Intravenous; Middle Aged; Myocardial Infarction; Prospective Studies; Prothrombin Time; Pulmonary Embolism; Recurrence; Thromboembolism; Thromboplastin; Thrombosis; Time Factors

Thrombin generation (TG) assays serve as a valuable tool to study the amplifying roles of intrinsic pathway factors in human coagulation and provide functional insights into the increased bleeding observed in individuals deficient in factors (F) XI, IX, or VIII. Mice are used extensively in hemostasis research owing to the availability of coagulation factor-deficient mice. However, phenotypic differences between mouse and human TG have become apparent. In this study, we describe a novel, calibrated mouse whole blood (WB) TG assay used to assess the amplifying roles of intrinsic pathway factors in mouse coagulation. WB- and plasma-TG was triggered with either silica or tissue factor (TF) in samples from wild-type mice and mice deficient for FXII, FXI, or FIX. Expectedly, silica-triggered WB-TG and platelet-poor plasma (PPP)-TG were significantly reduced by deficiencies for FXII, FXI, or FIX. FXII deficiency had no effect on WB-TG or PPP-TG when triggered with TF. However, FXI deficiency resulted in significantly reduced WB-TG triggered by low concentrations of TF but had no effect on TF-triggered PPP-TG. FIX deficiency profoundly reduced WB-TG when triggered by low or high concentrations of TF whereas TG in PPP or platelet-rich plasma was only moderately reduced under these conditions. In conclusion, we have developed a novel mouse WB-TG assay with enhanced sensitivity to FXI- and FIX-dependent amplification of coagulation compared with an established plasma-TG assay. The enhanced sensitivity of WB-TG to FXI and FIX-dependent amplification of coagulation suggests an important role of blood cells in this process.

Topics: Animals; Blood Coagulation; Factor IX; Factor XI; Hemorrhage; Hemostasis; Humans; Mice; Thrombin; Thromboplastin

The development of hemostatic materials suitable for diverse emergency scenarios is of paramount significance, and there is growing interest in wound-site delivery of hemostasis-enhancing agents that can leverage the body's inherent mechanisms. Herein we report the design and performance of a biomimetic nanoparticle system enclosing tissue factor (TF), the most potent known blood coagulation trigger, which was reconstituted into liposomes and shielded by the liposome-templated CaCO

Topics: Animals; Blood Coagulation; Carbon Dioxide; Hemorrhage; Hemostatics; Liposomes; Rats; Thromboplastin

Mim8 is a novel antifactor IXa/antifactor X bispecific antibody in clinical development for prophylactic treatment of hemophilia A with and without inhibitors. Patients treated with Mim8 may need supplementary bleed treatment under certain conditions such as surgery or major trauma.. This study aimed to better understand the response of Mim8 in thrombin generation assays (TGAs) alone or in combination with other hemostatic proteins.. We used TGAs with different activators (tissue factor (TF) and activated factor XI) to better understand the similarities and differences between the mode of action of Mim8 and factor VIII (FVIII). Following this, we investigated the effects of mixing Mim8 with the main bleed treatment options for persons with hemophilia A with or without inhibitors: FVIII, activated factor VII (FVIIa), and activated prothrombin complex concentrates (aPCC).. The results indicated that for patients without inhibitors, Mim8 does not interfere with FVIII's mode of action. For patients with inhibitors, Mim8 mixed with aPCC results in a strong synergistic effect causing thrombin generation far exceeding the normal levels. Contrary to this, mixing Mim8 with FVIIa results in a more controlled additive effect, visible only when using TF as a trigger, which does not exceed the normal level of thrombin generation.. These findings support the use of approved clinical doses of FVIIa for bleed treatment of patients with FVIII inhibitors treated with Mim8. Additionally, the findings suggest that concomitant use of FVIII and Mim8 is safe for managing breakthrough bleeds.

Topics: Factor IX; Factor VIIa; Factor VIII; Hemophilia A; Hemorrhage; Hemostatics; Humans; Recombinant Proteins; Thrombin; Thromboplastin

The purpose of this study was to describe the changes in plasma levels of angiogenic and inflammatory biomarkers, specifically Ang-2 and TNF-α, in patients receiving HeartMate II (HMII) left ventricular assist device (LVAD) and correlate them with nonsurgical bleeding. It has been shown that angiopoietin-2 (Ang-2) and tissue necrosis factor-α (TNF-α) may be linked to bleeding in LVAD patients. This study utilized biobanked samples prospectively collected from the PREVENT study, a prospective, multicenter, single-arm, nonrandomized study of patients implanted with HMII. Paired serum samples were obtained in 140 patients before implantation and at 90 days postimplantation. Baseline demographics were as follows: age 57 ± 13 years, 41% had ischemic etiology, 82% male, and 75% destination therapy indication. In the 17 patients with baseline elevation of both TNF-α and Ang-2, 10 (60%) experienced a significant bleeding event within 180 days postimplant compared with 37 of 98 (38%) patients with Ang-2 and TNF-α below the mean ( p = 0.02). The hazard ratio for a bleeding event was 2.3 (95% CI: 1.2-4.6) in patients with elevated levels of both TNF-α and Ang-2. In the PREVENT multicenter study, patients with elevations in serum Angiopoietin-2 and TNF-α at baseline before LVAD implantation demonstrated increased bleeding events after LVAD implantation.

Topics: Adult; Aged; Angiopoietin-2; Female; Heart Failure; Heart-Assist Devices; Hemorrhage; Humans; Male; Middle Aged; Necrosis; Prospective Studies; Retrospective Studies; Thromboplastin; Tumor Necrosis Factor-alpha

Rotational thromboelastometry (ROTEM) is used to rapidly identify trauma-induced coagulopathy (TIC) and direct targeted interventions in hemorrhaging trauma patients. A novel technology, Quantra System (HemoSonics), utilizes sonic estimation of elasticity via resonance sonorheometry, avoids mechanical clot interference, and may increase diagnostic accuracy, but there are limited data on bleeding in major trauma patients.. To compare the performance of Quantra with that of ROTEM for rapid diagnosis of TIC and prediction of transfusion requirements and mortality.. Samples were collected from adult trauma patients enrolled in a perpetual cohort study upon admission to a single level 1 trauma center between 2020 and 2021. Samples were analyzed using Quantra, ROTEM, multiple electrode aggregometry, and conventional coagulation assays.. Quantra and ROTEM have similar diagnostic performances in evaluating TIC and predicting clinically relevant outcomes. Larger studies are required to determine the utility of Quantra for goal-directed treatment of TIC.

Topics: Adult; Blood Coagulation Disorders; Cohort Studies; Fibrinogen; Hemorrhage; Humans; Prognosis; Thrombelastography; Thromboplastin

Acute promyelocytic leukemia (APL) is associated with a high risk of bleeding and thrombosis. APL patients have an activated coagulation system, hyperfibrinolysis, and thrombocytopenia. APL cells express tissue factor (TF), a receptor and cofactor for factor VII/VIIa. This study had 2 goals. Firstly, we measured biomarkers of coagulation and fibrinolysis activation as well as platelet counts and bleeding in both mouse xenograft and allograft models of APL. Secondly, we determined the effect of inhibiting TF on the activation of coagulation in these models. We observed increased levels of plasma thrombin-antithrombin complexes (TAT), D-dimer, and plasmin-antiplasmin complexes, reduced platelet counts, and increased tail bleeding in both mouse models of APL. Fibrinogen levels decreased in the xenograft model but not in the allograft model. In contrast, the red blood cell count decreased in the allograft model but not in the xenograft model. Inhibition of APL-derived human TF with an anti-human TF monoclonal antibody reduced the level of TAT, increased platelet count, and normalized tail bleeding in a xenograft model. Inhibition of all sources of TF (APL cells and host cells) in the allograft model with a rat anti-mouse TF monoclonal antibody decreased the levels of TAT but did not affect the platelet count. Our study demonstrates that TF plays a central role in the activation of coagulation in both the xenograft and allograft mouse models of APL. These APL mouse models can be used to investigate the mechanisms of coagulopathy and thrombocytopenia in APL.

Topics: Animals; Antibodies, Monoclonal; Blood Coagulation; Blood Coagulation Disorders; Hemorrhage; Humans; Leukemia, Promyelocytic, Acute; Rats; Thrombocytopenia; Thromboplastin

Tissue factor (TF) pathway inhibitor (TFPI) is a Kunitz-type anticoagulation protein that inhibits activated factor VII (FVIIa)/TF complex. Incidentally, many different F7 gene variants, including TFPI-binding exosite mutations, have been reported in patients with congenital FVII deficiency and clinical bleeding variabilities. Here, TFPI-binding exosites (R147 and K192) on FVII zymogen were selectively disrupted to understand their roles in the pathogenesis of bleeding phenotypes. Expression of recombinant FVII variants (R147A, K192A, and R147A/K192A) demonstrated markedly reduced secretion of FVII owing to intracellular retention in the endoplasmic reticulum, as demonstrated by upregulation of the unfolded protein response genes in all FVII variants. FVII variants showed a similar FVII activation pattern and FVIIa amidolytic activity than FVII wild-type (WT). In contrast to FVII activation, R147A and K192A showed a 90% reduction in FX activation relative to WT, whereas the R147A/K192A variant demonstrated a 99% decrease in FX activation. The clotting time was markedly prolonged with R147A and K192A than WT, and no FVII coagulant activity was detected in R147A/K192A. In addition, the thrombin generation assay revealed a significant prolongation of lag time in all FVII variants. Our study explains how mutations of TFPI-binding exosites of FVII can lead to bleeding phenotypes in individuals carrying these aberrancies.

Topics: Factor VII Deficiency; Factor VIIa; Hemorrhage; Humans; Mutation; Phenotype; Thromboplastin

 In factor XI (FXI) deficiency, bleeding cannot be predicted by routine analyses. Since FXI is involved in tissue factor (TF)-independent propagation loop of coagulation, we hypothesized that investigating the spatiotemporal separated phases of coagulation (TF-dependent and -independent) could improve diagnostics..  This article investigates the correlation of parameters describing TF-dependent and -independent coagulation with the clinical phenotype of FXI deficiency and their ability to assess hemostasis after FXI replacement..  We analyzed: (1) plasma from healthy controls (.  C7P dose-dependently decreased FXI activity, prolonged activated partial thromboplastin time, and hampered TF-independent coagulation. In FXI-deficient bleeders, TD parameters describing TF-independent propagation of coagulation and fibrin clot formation were reduced compared with controls and FXI-deficient nonbleeders and increased in FXI-deficient patients with prothrombotic phenotype. Receiver operating characteristic analysis indicated that TF-independent parameters were useful for discriminating FXI-deficient bleeders from non-bleeders. In FXI-deficient plasma spiked with FXI concentrate and in patients receiving FXI replacement, TD parameters were shifted toward hypercoagulation already at plasma FXI levels around 20%..  TF-independent coagulation parameters assessed by TD have the potential to identify the clinical phenotype in FXI-deficient patients and to monitor FXI replacement therapy.

Topics: Blood Coagulation; Factor XI; Factor XI Deficiency; Hemorrhage; Humans; Prognosis; Thrombin; Thromboplastin

Lipopolysaccharide (LPS) and tissue factor (TF) have frequently been used to induce disseminated intravascular coagulation (DIC) in experimental animal models. We have previously reported that the pathophysiology of DIC differs according to the inducing agents. However, inflammatory status and bleeding symptoms have not been fully compared between rat models of the two forms of DIC. We attempted to evaluate detailed characteristic features of LPS- and TF-induced DIC models, especially in regard to inflammatory status and bleeding symptoms, in addition to selected hemostatic parameters and pathologic findings in the kidneys. The degree of hemostatic activation in both types of experimental DIC was identical, based on the results of thrombin-antithrombin complex levels. Markedly elevated tumor necrosis factor, interleukin-6, and high-mobility group box-1 concentrations were observed with severe organ dysfunction and marked fibrin deposition in the kidney on administration of LPS, whereas markedly elevated D-dimer concentration and bleeding symptoms were observed with TF administration. Pathophysiology such as fibrinolytic activity, organ dysfunction, inflammation status, and bleeding symptom differed markedly between LPS- and TF-induced DIC models in rats. We, therefore, recommend that these disease models be assessed carefully as distinct entities to determine the implications of their experimental and clinical use.

Topics: Animals; Biomarkers; Blood Coagulation; Blood Coagulation Tests; Disease Models, Animal; Disease Susceptibility; Disseminated Intravascular Coagulation; Hemorrhage; Humans; Lipopolysaccharides; Male; Prognosis; Rats; Thromboplastin

Noncompressible torso hemorrhage accounts for a significant portion of preventable trauma deaths. We report here on the development of injectable, targeted supramolecular nanotherapeutics based on peptide amphiphile (PA) molecules that are designed to target tissue factor (TF) and, therefore, selectively localize to sites of injury to slow hemorrhage. Eight TF-targeting sequences were identified, synthesized into PA molecules, coassembled with nontargeted backbone PA at various weight percentages, and characterized

Topics: Animals; Hemorrhage; Mice; Nanofibers; Peptides; Rats; Thromboplastin; Torso

Tissue factor is highly expressed in sub-endothelial tissue. The extracellular allosteric disulfide bond Cys186-Cys209 of human tissue factor shows high evolutionary conservation and in vitro evidence suggests that it significantly contributes to tissue factor procoagulant activity. To investigate the role of this allosteric disulfide bond in vivo, we generated a C213G mutant tissue factor mouse by replacing Cys213 of the corresponding disulfide Cys190-Cys213 in murine tissue factor. A bleeding phenotype was prominent in homozygous C213G tissue factor mice. Pre-natal lethality of 1/3rd of homozygous offspring was observed between E9.5 and E14.5 associated with placental hemorrhages. After birth, homozygous mice suffered from bleedings in different organs and reduced survival. Homozygous C213G tissue factor male mice showed higher incidence of lung bleedings and lower survival rates than females. In both sexes, C213G mutation evoked a reduced protein expression (about 10-fold) and severely reduced pro-coagulant activity (about 1000-fold). Protein glycosylation was impaired and cell membrane exposure decreased in macrophages in vivo. Single housing of homozygous C213G tissue factor males reduced the occurrence of severe bleeding and significantly improved survival, suggesting that inter-male aggressiveness might significantly account for the sex differences. These experiments show that the tissue factor allosteric disulfide bond is of crucial importance for normal in vivo expression, post-translational processing and activity of murine tissue factor. Although C213G tissue factor mice do not display the severe embryonic lethality of tissue factor knock-out mice, their postnatal bleeding phenotype emphasizes the importance of fully functional tissue factor for hemostasis.

Topics: Animals; Disulfides; Female; Hemorrhage; Male; Mice; Mutation; Phenotype; Pregnancy; Thromboplastin

Topics: Animals; Antibodies, Monoclonal, Humanized; Disease Models, Animal; Factor VIIa; Female; Hemophilia A; Hemorrhage; Hemostasis; Rabbits; Thromboplastin

Hemostatic defects are treated using coagulation factors; however, clot formation also requires a procoagulant phospholipid (PL) surface. Here, we show that innate immune cell-derived enzymatically oxidized phospholipids (eoxPL) termed hydroxyeicosatetraenoic acid-phospholipids (HETE-PLs) restore hemostasis in human and murine conditions of pathological bleeding. HETE-PLs abolished blood loss in murine hemophilia A and enhanced coagulation in factor VIII- (FVIII-), FIX-, and FX-deficient human plasma . HETE-PLs were decreased in platelets from patients after cardiopulmonary bypass (CPB). To explore molecular mechanisms, the ability of eoxPL to stimulate individual isolated coagulation factor/cofactor complexes was tested in vitro. Extrinsic tenase (FVIIa/tissue factor [TF]), intrinsic tenase (FVIIIa/FIXa), and prothrombinase (FVa/FXa) all were enhanced by both HETE-PEs and HETE-PCs, suggesting a common mechanism involving the fatty acid moiety. In plasma, 9-, 15-, and 12-HETE-PLs were more effective than 5-, 11-, or 8-HETE-PLs, indicating positional isomer specificity. Coagulation was enhanced at lower lipid/factor ratios, consistent with a more concentrated area for protein binding. Surface plasmon resonance confirmed binding of FII and FX to HETE-PEs. HETE-PEs increased membrane curvature and thickness, but not surface charge or homogeneity, possibly suggesting increased accessibility to cations/factors. In summary, innate immune-derived eoxPL enhance calcium-dependent coagulation factor function, and their potential utility in bleeding disorders is proposed.

Topics: Adult; Aged; Aged, 80 and over; Animals; Blood Coagulation; Blood Coagulation Factors; Blood Platelets; Cardiopulmonary Bypass; Carrier Proteins; Cysteine Endopeptidases; Factor IX; Factor VIIa; Factor VIII; Factor X; Hemophilia A; Hemorrhage; Hemostasis; Humans; Hydroxyeicosatetraenoic Acids; Lipoproteins; Male; Mice; Mice, Inbred C57BL; Middle Aged; Neoplasm Proteins; Phospholipids; Surface Plasmon Resonance; Thrombin; Thromboplastin

Topics: Adolescent; Adult; Blood Coagulation; Child; Child, Preschool; Factor VIII; Hemophilia A; Hemorrhage; Humans; Indicators and Reagents; Middle Aged; Partial Thromboplastin Time; Recombinant Proteins; Thrombelastography; Thromboplastin; Young Adult

Essentials Heparanase forms a complex with tissue factor and enhances the generation of factor Xa. The present study was aimed to identify the procoagulant domain of heparanase. Procoagulant peptides significantly shortened bleeding time and enhanced wound healing. Tissue factor pathway inhibitor (TFPI)-2 derived peptides inhibited the procoagulant peptides.. Background Heparanase, which is known to be involved in angiogenesis and metastasis, was shown to form a complex with tissue factor (TF) and to enhance the generation of activated factor X (FXa). Our study demonstrated that peptides derived from TF pathway inhibitor (TFPI)-2 impeded the procoagulant effect of heparanase, and attenuated inflammation, tumor growth, and vascularization. Aims To identify the procoagulant domain in the heparanase molecule, and to evaluate its effects in a model of wound healing that involves inflammation and angiogenesis. Methods Twenty-four potential peptides derived from heparanase were generated, and their effect was studied in an assay of FXa generation. Peptides 14 and 16, which showed the best procoagulant effect, were studied in a bleeding mouse model and in a wound-healing mouse model. Results Peptides 14 and 16 increased FXa levels by two-fold to three-fold, and, at high levels, caused consumption coagulopathy. The TFPI-2-derived peptides explored in our previous study were found to inhibit the procoagulant effect induced by peptides 14 and 16. In the bleeding model, time to clot formation was shortened by 50% when peptide 14 or peptide 16 was topically applied or injected subcutaneously. In the wound-healing model, the wound became more vascular, and its size was reduced to one-fifth as compared with controls, upon 1 week of exposure to peptide 14 or peptide 16 applied topically or injected subcutaneously. Conclusions The putative heparanase procoagulant domain was identified. Peptides derived from this domain significantly shortened bleeding time and enhanced wound healing.

Topics: Animals; Blood Coagulation; Coagulants; Factor Xa; Fibrin Fibrinogen Degradation Products; Fibrinogen; Glucuronidase; Glycoproteins; Hematologic Agents; Hemorrhage; Humans; Inflammation; Male; Mice; Neoplasm Metastasis; Neovascularization, Pathologic; Partial Thromboplastin Time; Peptides; Protein Domains; Prothrombin Time; Thrombelastography; Thromboplastin; Thrombosis; Wound Healing

Early onset preeclampsia (EOP) is a pregnancy-specific proinflammatory disorder that is characterised by competing thrombotic and bleeding risks. It was the aim of this study to characterise thrombin generation, a major determinant of thrombotic and bleeding risk, in order to better understand the haemostatic balance in patients with EOP. Patients with EOP were recruited at the Rotunda Hospital, Dublin. Twenty-six cases of EOP were recruited over a 21-month period, out of 15,299 deliveries at the Rotunda. Blood samples were collected into sodium citrate plus corn trypsin inhibitor anticoagulated vacutainers, platelet-poor plasma was prepared, and calibrated automated thrombography was used to assess thrombin generation. Results were compared to age and sex-matched non-pregnant controls (n=13) and age- and gestation-matched pregnant controls (n=20). The rate and extent of thrombin generation triggered by low-dose tissue factor (TF) was significantly reduced in patients with EOP compared to pregnant controls, most significantly in cases of severe EOP. EOP patients displayed a trend towards an increased response to endogenous activated protein C and thrombomodulin relative to pregnant controls. Plasma tissue factor pathway inhibitor (TFPI) activity was increased in EOP patients. Inhibition of TFPI abolished the attenuation of thrombin generation stimulated by low-dose TF. In conclusion, patients with EOP are characterised by an attenuated coagulation response characterised by reduced thrombin generation stimulated by low-dose TF and elevated plasma TFPI activity. These changes in coagulation may modulate thrombotic risk and bleeding risk in patients with EOP.

Topics: Adult; Biomarkers; Blood Coagulation; Blood Coagulation Tests; Carboxypeptidase B2; Case-Control Studies; Female; Gestational Age; Hemorrhage; Humans; Ireland; Pre-Eclampsia; Pregnancy; Prognosis; Protein C; Protein S; Risk Factors; Thrombin; Thrombomodulin; Thromboplastin; Thrombosis; Up-Regulation

Tissue cross-reactivity (TCR) studies are conducted when developing therapeutic antibodies, but their value is sometimes questioned because the positive organs often do not match the target organs of toxicity. We conducted TCR studies in human and cynomolgus monkey tissues for the development of an anti-human tissue factor antibody (TFAb) and also for a commercially available antibody, to clarify the true distribution of the target antigen. Tissue factor (TF) was found to be distributed in a wide variety of organs and tissues, including the heart and urinary bladder, in human and monkey. Administration of the TFAb to cynomolgus monkey caused hemorrhagic lesions mainly in the heart and urinary bladder in an incidental manner. This was thought to show the physiological role of TF in regulating hemostasis in these organs. Because the distribution of antigen in human and monkey was similar, the possibility that the TFAb would have similar effects in human was judged to be high, and because of the incidental nature of the effects, that they would be difficult to avoid. Thus it was possible to prospectively characterize the hazardous potential of a therapeutic antibody by accurately evaluating the tissue distribution of the target antigen and understanding its biological nature.

Topics: Animals; Antibodies, Monoclonal; Antigens; Cross Reactions; Female; Hemorrhage; Humans; Immunoglobulin G; Immunoglobulin kappa-Chains; Macaca fascicularis; Male; Thromboplastin; Tissue Distribution; Toxicity Tests

We present a methodology for personalizing the clinical treatment of severely injured patients with acute traumatic coagulopathy (ATC), an endogenous biological response of impaired coagulation that occurs early after trauma and shock and that is associated with increased bleeding, morbidity, and mortality. Despite biological characterization of ATC, it is not easily or rapidly diagnosed, not always captured by slow laboratory testing, and not accurately represented by coagulation models. This lack of knowledge, combined with the inherent time pressures of trauma treatment, forces surgeons to treat ATC patients according to empirical resuscitation protocols. These entail transfusing large volumes of poorly characterized, nontargeted blood products that are not tailored to an individual, the injury, or coagulation dynamics. Massive transfusion mortality remains at 40 to 70% in the best of trauma centers. As an alternative to blunt treatments, time-consuming tests, and mechanistic models, we used dynamical systems theory to create a simple, biologically meaningful, and highly accurate model that (i) quickly forecasts a driver of downstream coagulation, thrombin concentration after tissue factor stimulation, using rapidly measurable concentrations of blood protein factors and (ii) determines the amounts of additional coagulation factors needed to rectify the predicted thrombin dynamics and potentially remedy ATC. We successfully demonstrate in vitro thrombin control consistent with the model. Compared to another model, we decreased the mean errors in two key trauma patient parameters: peak thrombin concentration after tissue factor stimulation and the time until this peak occurs. Our methodology helps to advance individualized resuscitation of trauma-induced coagulation deficits.

Topics: Adult; Aged; Blood Coagulation; Blood Coagulation Disorders; Blood Transfusion; Calibration; Female; Hemorrhage; Humans; Male; Middle Aged; Prospective Studies; Thrombin; Thromboplastin; Thrombosis; Treatment Outcome; Wounds and Injuries

Thrombin generation test (TGT) is a global haemostasis assay with a potential to predict bleeding tendencies and treatment effects in patients with haemophilia. Despite 15 years of clinical research, the diagnostic value of TGT remains controversial, possibly due to suboptimal sensitivity to coagulation deficiencies, robustness and reproducibility.. The goal of this study was to explore the effect of calcium chloride (CaCl. Normal and factor-deficient plasmas supplemented with lacking coagulation factor and different CaCl. Thrombin peak height (TPH) was strongly CaCl. Variations in CaCl

Topics: Blood Chemical Analysis; Calcium Chloride; Dose-Response Relationship, Drug; Hemophilia A; Hemorrhage; Hemostasis; Thrombin; Thromboplastin

Noncompressible torso hemorrhage is a leading cause of mortality in civilian and battlefield trauma. We sought to develop an i.v.-injectable, tissue factor (TF)-targeted nanotherapy to stop hemorrhage. Tissue factor was chosen as a target because it is only exposed to the intravascular space upon vessel disruption. Peptide amphiphile (PA) monomers that self-assemble into nanofibers were chosen as the delivery vehicle. Three TF-binding sequences were identified (EGR, RLM, and RTL), covalently incorporated into the PA backbone, and shown to self-assemble into nanofibers by cryo-transmission electron microscopy. Both the RLM and RTL peptides bound recombinant TF in vitro. All three TF-targeted nanofibers bound to the site of punch biopsy-induced liver hemorrhage in vivo, but only RTL nanofibers reduced blood loss versus sham (53% reduction, p < 0.05). Increasing the targeting ligand density of RTL nanofibers yielded qualitatively better binding to the site of injury and greater reductions in blood loss in vivo (p < 0.05). In fact, 100% RTL nanofiber reduced overall blood loss by 60% versus sham (p < 0.05). Evaluation of the biocompatibility of the RTL nanofiber revealed that it did not induce RBC hemolysis, did not induce neutrophil or macrophage inflammation at the site of liver injury, and 70% remained intact in plasma after 30 min. In summary, these studies demonstrate successful binding of peptides to TF in vitro and successful homing of a TF-targeted PA nanofiber to the site of hemorrhage with an associated decrease in blood loss in vivo. Thus, this therapeutic may potentially treat noncompressible hemorrhage.

Topics: Amino Acid Sequence; Animals; Blood Vessels; Fluorenes; Hemorrhage; Injections, Intralesional; Liver; Male; Molecular Sequence Data; Molecular Targeted Therapy; Nanofibers; Peptides; Protein Binding; Rats; Rats, Sprague-Dawley; Thromboplastin

Essentials H1N1 Influenza A virus (IAV) infection is a hemostatic challenge for the lung. Tissue factor (TF) on lung epithelial cells maintains lung hemostasis after IAV infection. Reduced TF-dependent activation of coagulation leads to alveolar hemorrhage. Anticoagulation might increase the risk for hemorrhages into the lung during severe IAV infection.. Background Influenza A virus (IAV) infection is a common respiratory tract infection that causes considerable morbidity and mortality worldwide. Objective To investigate the effect of genetic deficiency of tissue factor (TF) in a mouse model of IAV infection. Methods Wild-type mice, low-TF (LTF) mice and mice with the TF gene deleted in different cell types were infected with a mouse-adapted A/Puerto Rico/8/34 H1N1 strain of IAV. TF expression was measured in the lungs, and bronchoalveolar lavage fluid (BALF) was collected to measure extracellular vesicle TF, activation of coagulation, alveolar hemorrhage, and inflammation. Results IAV infection of wild-type mice increased lung TF expression, activation of coagulation and inflammation in BALF, but also led to alveolar hemorrhage. LTF mice and mice with selective deficiency of TF in lung epithelial cells had low basal levels of TF and failed to increase TF expression after infection; these two strains of mice had more alveolar hemorrhage and death than controls. In contrast, deletion of TF in either myeloid cells or endothelial cells and hematopoietic cells did not increase alveolar hemorrhage or death after IAV infection. These results indicate that TF expression in the lung, particularly in epithelial cells, is required to maintain alveolar hemostasis after IAV infection. Conclusion Our study indicates that TF-dependent activation of coagulation is required to limit alveolar hemorrhage and death after IAV infection.

Topics: Animals; Anticoagulants; Blood Coagulation; Bronchoalveolar Lavage Fluid; Epithelial Cells; Gene Deletion; Hemorrhage; Hemostasis; Inflammation; Influenza A Virus, H1N1 Subtype; Integrases; Lung; Male; Mice; Mice, Inbred C57BL; Orthomyxoviridae Infections; Pulmonary Alveoli; Thromboplastin

The clinical phenotype of von Willebrand disease (VWD) is heterogeneous, and von Willebrand factor ristocetin cofactor activity (VWF:RCo) does not always reflect clinical severity, especially in VWD type 1. We have reported the potential of a microchip flow-chamber system (Total-Thrombus Formation Analysis System [T-TAS®]) for assessing physiologic hemostasis in VWD. Aim To evaluate the relationship between T-TAS, bleeding score (BS) and laboratory test results in type 1 VWD patients.. Microchips coated with collagen (platelet chip [PL-chip]) or collagen/thromboplastin (AR-chip) were used to assess platelet thrombus formation (PTF) at high shear rates or fibrin-rich PTF at low shear rates, respectively, in whole blood from 50 patients. The times needed for the flow pressure to increase by 10 kPa and 30 kPa (T10 and T30 ) from baseline were calculated from flow pressure curves. BS was determined by the use of a standardized questionnaire.. PL-T10 values correlated with BS (R(2) ~ 0.45) better than VWF:RCo (R(2) ~ 0.36), irrespective of the flow rate, whereas AR-T10 showed only a weak correlation with BS (R(2) ~ 0.18). Patients with PL-T10 > 10 min or AR-T10 > 30 min had lower VWF levels and higher BS than those with PL-T10 ≤ 10 min or AR-T10 ≤ 30 min, and the greatest differences were observed with PL-T10. Clinical severity appeared to correlate best with PL-T10 > 8 min. BS was significantly higher in patients with VWF:RCo of < 10 IU dL(-1) than in those with VWF:RCo of 10 IU dL(-1) to < 25 IU dL(-1) and 25-40 IU dL(-1). In patients with VWF:RCo of < 10 IU dL(-1) , BS was significantly higher in those with PL-T10 > 8 min than in those with PL-T10 ≤ 8 min.. T-TAS could be a useful technique for discriminating and predicting BS in VWD type 1 patients.

Topics: Adolescent; Adult; Aged; Case-Control Studies; Child; Child, Preschool; Collagen; Female; Hemorrhage; Hemostasis; Humans; Infant; Male; Microfluidic Analytical Techniques; Microfluidics; Middle Aged; Phenotype; Pressure; Severity of Illness Index; Shear Strength; Stress, Mechanical; Surveys and Questionnaires; Thromboplastin; Thrombosis; von Willebrand Disease, Type 1; von Willebrand Factor; Young Adult

Mice with a complete absence of tissue factor (TF) die during embryonic development whereas mice with low levels of TF (Low-TF mice) survive to adulthood. Low-TF mice exhibit spontaneous hemorrhage in various organs, including the lung. In contrast, mice can survive without protease-activated receptor (PAR)-4, which is the major thrombin receptor on mouse platelets. We determined the effect of combining a deficiency PAR-4 (primary hemostasis) with a deficiency in TF (secondary hemostasis) on embryonic development and survival of adult mice.. Low-TF mice (mTF. We observed the expected number of Low-TF,PAR-4. Low-TF,PAR-4

Topics: Animals; Disease Models, Animal; Hemorrhage; Humans; Lung Diseases; Mice; Mice, Transgenic; Receptors, Proteinase-Activated; Thromboplastin

Dengue haemorrhagic fever (DHF) typically occurs during secondary infections with dengue viruses (DENVs). Although it is generally accepted that antibody-dependent enhancement is the primary reason why patients with secondary infection are at an increased risk of developing DHF, a growing body of evidence shows that other mechanisms, such as the elicitation of antiplatelet autoantibodies by DENV nonstructural protein NS1, also play crucial roles in the pathogenesis of DHF. In this study, we developed a "two-hit" model of secondary DENV infection to examine the respective roles of DENV (first hit) and antiplatelet Igs (second hit) on the induction of haemorrhage. Mice were first exposed to DENV and then exposed to antiplatelet or anti-NS1 Igs 24 hours later. The two-hit treatment induced substantial haemorrhage, coagulopathy, and cytokine surge, and additional treatment with antagonists of TNF-α, IL-1, caspase-1, and FcγRIII ameliorated such effects. In addition, knockout mice lacking the Fcγ receptor III, Toll-like receptor 3, and inflammasome components Nlrp3 and caspase-1 exhibited considerably fewer pathological alterations than did wild type controls. These findings may provide new perspectives for developing feasible approaches to treat patients with DHF.

Topics: Animals; Antibodies, Viral; Autoantibodies; Carrier Proteins; Dengue Virus; Female; Hemorrhage; Inflammasomes; Interleukin-1; Leukocytes; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; NLR Family, Pyrin Domain-Containing 3 Protein; Receptors, IgG; Recombinant Proteins; Severe Dengue; Thromboplastin; Toll-Like Receptor 3

Tissue factor (TF) initiates the extrinsic coagulation cascade in response to tissue injury, leading to local fibrin deposition. Low levels of TF in mice are associated with increased severity of acute lung injury (ALI) after intratracheal LPS administration. However, the cellular sources of the TF required for protection from LPS-induced ALI remain unknown. In the current study, transgenic mice with cell-specific deletions of TF in the lung epithelium or myeloid cells were treated with intratracheal LPS to determine the cellular sources of TF important in direct ALI. Cell-specific deletion of TF in the lung epithelium reduced total lung TF expression to 39% of wild-type (WT) levels at baseline and to 29% of WT levels after intratracheal LPS. In contrast, there was no reduction of TF with myeloid cell TF deletion. Mice lacking myeloid cell TF did not differ from WT mice in coagulation, inflammation, permeability, or hemorrhage. However, mice lacking lung epithelial TF had increased tissue injury, impaired activation of coagulation in the airspace, disrupted alveolar permeability, and increased alveolar hemorrhage after intratracheal LPS. Deletion of epithelial TF did not affect alveolar permeability in an indirect model of ALI caused by systemic LPS infusion. These studies demonstrate that the lung epithelium is the primary source of TF in the lung, contributing 60-70% of total lung TF, and that lung epithelial, but not myeloid, TF may be protective in direct ALI.

Topics: Acute Lung Injury; Animals; Blood Coagulation; Capillary Permeability; Disease Models, Animal; Epithelial Cells; Gene Expression; Hemorrhage; Lipopolysaccharides; Mice; Mice, Knockout; Myeloid Cells; Pulmonary Alveoli; Respiratory Distress Syndrome; Respiratory Mucosa; Thromboplastin

In trauma patients, resuscitation treatment of intravascular volume may cause haemodilution including blood cell- and plasma-dilution. After plasma-dilution, fibrinogen is the first factor that decreases to critically low concentrations. Fibrin formed in lowered levels is susceptible to fibrinolysis, a natural forerunner for bleeding. To assess whether a fibrinogen concentrate or a factor XIII (FXIII) concentrate can reverse the impairment of fibrin properties after plasma dilution, different laboratory methods were used to determine thrombin generation and fibrin quantity/quality in a normal plasma sample diluted in vitro. Coagulation and clot lysis by plasmin were triggered with tissue factor and rt-PA, respectively.We found that while the endogenous thrombin potential (ETP) was unaffected after plasma-dilution due to postponement of thrombin decay, levels of fibrinogen and hence fibrin were decreased in dilution degree-dependency. The imbalance between influence of the dilution on thrombin activity and fibrin formation brought unexpected outcomes of fibrin properties: the formed clots favoured the degradation by plasminbut the fibrin networks remained tighter/less permeable. This proteolytic tendency was partly overturned by the fibrinogen concentrate added (total fibrinogen ≥ 2 g/l), and much more affected if used in combination with tranexamic acid (a fibrinolysis inhibitor) at small doses. No reversal effect resulted from the FXIII concentrate added. We conclude that plasma-dilution did reduce the proteolytic resistance of formed clots. The fibrinogen concentrate, better together with small doses of tranexamic acid, may reverse the impairment of fibrin property.The FXIII concentrate is not effective in this regard in our in vitro model using platelet-poor plasma.

Topics: Blood Coagulation; Factor XIII; Fibrinogen; Fibrinolysin; Fibrinolysis; Hemodilution; Hemorrhage; Humans; In Vitro Techniques; Plasma; Proteolysis; Resuscitation; Thromboplastin; Tranexamic Acid; Wounds and Injuries

The clinical courses of polycythemia vera (PV) and essential thrombocythemia (ET) are characterized by thrombohemorrhagic diathesis. Several groups have suggested an association between JAK2V617F mutation and thrombosis. We hypothesized a relationship between JAK2V617F allele burden, cellular activation parameters, and thrombosis. We evaluated a group of PV and ET patients using flow cytometry: platelet CD62P, CD63, and dense granules, platelet-leukocyte aggregates (PLA), leukocyte CD11b and monocyte tissue factor (TF) expression. All patients had increased baseline platelet CD62P and CD63 expression (p < 0.05); 71 % of PV and 47 % of ET presented with a storage pool disease. Leukocyte CD11b, TF, and PLA were elevated in all patients. TF was higher in PV compared to ET (p < 0.05) and platelet-neutrophil [polymorphonuclear (PMN)] aggregates were increased in ET versus PV (p < 0.05). In ET, PLA were correlated with platelet numbers (p < 0.05). In all patients, JAK2V617F allele burden was directly correlated with monocyte CD11b. Patients with JAK2V617F allele burden >50 % presented higher levels of leukocyte activation. In ET, thrombosis was associated with JAK2V617F mutation (p < 0.05, χ (2) = 5.2), increased monocyte CD11b (p < 0.05) and with platelet-PMN aggregates (p < 0.05). In ET patients, hydroxyurea does not significantly reduce the activation parameters. Our data demonstrate that JAK2V617F allele burden is directly correlated with activation parameters that drive mechanisms that favor thrombosis.

Topics: Adult; Aged; Aged, 80 and over; Alleles; Blood Platelets; Case-Control Studies; CD11b Antigen; Codon; Female; Hemorrhage; Humans; Janus Kinase 2; Male; Middle Aged; Monocytes; Mutation; Neutrophils; Platelet Activation; Platelet Aggregation; Polycythemia Vera; Quinacrine; Thrombocythemia, Essential; Thromboplastin; Thrombosis; Young Adult

Activated factor VII is approved for treating hemophilia patients with autoantibodies to their factor IX or FVIII; however, its mechanism of action remains controversial. Some studies suggest that FVIIa requires tissue factor (TF) for function and that the reason for the high dose requirement is that it must compete with endogenous FVII for tissue factor. Others suggest that FVIIa binds platelets where it activates FX directly; the high concentration required would result from FVIIa's weak affinity for phospholipids. We address this question by infusing a chimera of mouse FIX (Gla and EGF1) with FVIIa (EGF2 and catalytic domain) into hemophilia B mice. This mutant has no TF-dependent activity because it cannot functionally bind TF at physiologically relevant concentrations. In vivo, this mutant is as effective as mouse FVIIa in controlling bleeding in hemophilia B mice. Our results suggest that the hemostatic effect of pharmacologic doses of FVIIa is TF independent.

Topics: Animals; Binding Sites; Factor IX; Factor VIIa; Hemophilia B; Hemorrhage; Hemostasis; Humans; Mice; Mice, Inbred C57BL; Models, Molecular; Saphenous Vein; Thromboplastin

Topics: Animals; Factor IX; Factor VIIa; Hemophilia B; Hemorrhage; Hemostasis; Humans; Thromboplastin

Some hemophilia A patients who have developed inhibitors are poorly responsive to activated prothrombin complex concentrates (aPCC) after daily dosage, but the mechanism(s) underlying this remain unknown. We examined two representative cases. In case 1, we found that changing to recombinant factor VIIa (rFVIIa) therapy was more effective, and the response to aPCC was restored within ~2 weeks. Tissue factor (TF)-triggered thrombin generation demonstrated a prolonged lag-time and decreased peak thrombin, and this impairment was focused on TF pathway inhibitor (TFPI). Plasma-free TFPI was elevated post-infusion of aPCC, while this was unaffected by rFVIIa. TFPI returned to normal range within 2-3 weeks. Plasmas obtained from patients with poor or good response to aPCC (aPCC-poor or aPCC-good), and good response to rFVIIa (FVIIa-good) demonstrated that free TFPI levels are increased in both aPCC groups, but not in FVIIa-good. TFPI levels pre- and post-infusion in aPCC-poor were significantly higher than those in aPCC-good. Addition of anti-TFPI antibody to the reaction samples demonstrated a greater increase of peak thrombin in aPCC-poor compared to aPCC-good, showing the higher TFPI activity in aPCC-poor. Free TFPI contained in aPCC corresponded to the increasing levels in plasma. In conclusion, TFPI in aPCC attenuated thrombin generation, and the reduced effectiveness of therapy in these circumstances appeared to be related to TFPI activity.

Topics: Antibodies, Anti-Idiotypic; Antibodies, Monoclonal; Blood Coagulation; Blood Coagulation Factors; Blood Coagulation Tests; Child, Preschool; Factor VIIa; Factor VIII; Hemophilia A; Hemorrhage; Humans; Isoantibodies; Male; Recombinant Proteins; Severity of Illness Index; Thromboplastin; Treatment Outcome; Young Adult

Bleeding tendency, coagulopathy and platelet disorders are recurrent manifestations in snakebites occurring worldwide. We reasoned that by damaging tissues and/or activating cells at the site of the bite and systemically, snake venom toxins might release or decrypt tissue factor (TF), resulting in activation of blood coagulation and aggravation of the bleeding tendency. Thus, we addressed (a) whether TF and protein disulfide isomerase (PDI), an oxireductase involved in TF encryption/decryption, were altered in experimental snake envenomation; (b) the involvement and significance of snake venom metalloproteinases (SVMP) and serine proteinases (SVSP) to hemostatic disturbances.. Crude Bothrops jararaca venom (BjV) was preincubated with Na2-EDTA or AEBSF, which are inhibitors of SVMP and SVSP, respectively, and injected subcutaneously or intravenously into rats to analyze the contribution of local lesion to the development of hemostatic disturbances. Samples of blood, lung and skin were collected and analyzed at 3 and 6 h. Platelet counts were markedly diminished in rats, and neither Na2-EDTA nor AEBSF could effectively abrogate this fall. However, Na2-EDTA markedly reduced plasma fibrinogen consumption and hemorrhage at the site of BjV inoculation. Na2-EDTA also abolished the marked elevation in TF levels in plasma at 3 and 6 h, by both administration routes. Moreover, increased TF activity was also noticed in lung and skin tissue samples at 6 h. However, factor VII levels did not decrease over time. PDI expression in skin was normal at 3 h, and downregulated at 6 h in all groups treated with BjV.. SVMP induce coagulopathy, hemorrhage and increased TF levels in plasma, but neither SVMP nor SVSP are directly involved in thrombocytopenia. High levels of TF in plasma and TF decryption occur during snake envenomation, like true disseminated intravascular coagulation syndrome, and might be implicated in engendering bleeding manifestations in severely-envenomed patients.

Topics: Animals; Blood Coagulation Disorders; Blood Coagulation Tests; Blood Platelets; Bothrops; Crotalid Venoms; Edetic Acid; Fibrinogen; Hemorrhage; Lung; Male; Metalloproteases; Prothrombin; Rats; Rats, Wistar; Serine Proteases; Serine Proteinase Inhibitors; Skin; Sulfones; Thrombocytopenia; Thromboplastin

The clinical phenotype of individuals with acquired factor V (A-FV) inhibitors varies from asymptomatic (non-B group) to life-threatening bleeding (B group), but the mechanism(s) underlying this variation in hemorrhagic phenotype are poorly understood.. To investigate coagulation mechanistically in a range of patients with A-FV antibodies.. Ten cases of A-FV inhibitors in the non-B (n = 5) and B groups (n = 5) were studied. Thrombin generation assays in these plasmas revealed little thrombin generation, despite similar FV activity levels in both groups. However, prothrombin time-based clot waveform analysis revealed that the clot times were significantly prolonged and the maximum velocity and acceleration of coagulation were lower in the B group than in the non-B group, suggesting that this technique might be useful for predicting and monitoring hemorrhagic symptoms. A-FV inhibitors from the non-B group recognized predominantly the FV heavy chain, whereas those from the B group recognized the light chain. Purified anti-FV autoantibodies (autoAbs) from the B group inhibited FV binding to phospholipid by 60-90%, whereas there was little effect on this reaction in the non-B group. In addition, anti-FV autoAbs from the non-B group impaired the activated protein C (APC) cofactor activity of FV in FVIIIa inactivation mechanisms, and delayed APC-catalyzed cleavage of FVa at Arg306, but not at Arg506, indicating the presence of APC resistance in the non-B group.. The results suggest that the different hemorrhagic phenotypes in A-FV inhibitors depend on the specific epitope of anti-FV autoAbs, and appear to be associated with an imbalance of procoagulant and anticoagulant function.

Topics: Anticoagulants; Blood Coagulation; Blood Coagulation Tests; Coagulants; Epitopes; Factor V; Factor Va; Female; Hemorrhage; Hemostasis; Humans; Male; Partial Thromboplastin Time; Phenotype; Protein Binding; Protein C; Prothrombin; Prothrombin Time; Thromboplastin

Trauma-induced coagulopathy following severe injury is associated with increased bleeding and mortality. Injury may result in alteration of cellular phenotypes and release of cell-derived microparticles (MP). Circulating MPs are procoagulant and support thrombin generation (TG) and clotting. We evaluated MP and TG phenotypes in severely injured patients at admission, in relation to coagulopathy and bleeding.. As part of the Prospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study, research blood samples were obtained from 180 trauma patients requiring transfusions at 5 participating centers. Twenty five healthy controls and 40 minimally injured patients were analyzed for comparisons. Laboratory criteria for coagulopathy was activated partial thromboplastin time (APTT) ≥ 35 sec. Samples were analyzed by Calibrated Automated Thrombogram to assess TG, and by flow cytometry for MP phenotypes [platelet (PMP), erythrocyte (RMP), leukocyte (LMP), endothelial (EMP), tissue factor (TFMP), and Annexin V positive (AVMP)].. 21.7% of patients were coagulopathic with the median (IQR) APTT of 44 sec (37, 53), and an Injury Severity Score of 26 (17, 35). Compared to controls, patients had elevated EMP, RMP, LMP, and TFMP (all p<0.001), and enhanced TG (p<0.0001). However, coagulopathic PROMMTT patients had significantly lower PMP, TFMP, and TG, higher substantial bleeding, and higher mortality compared to non-coagulopathic patients (all p<0.001).. Cellular activation and enhanced TG are predominant after trauma and independent of injury severity. Coagulopathy was associated with lower thrombin peak and rate compared to non-coagulopathic patients, while lower levels of TF-bearing PMPs were associated with substantial bleeding.

Topics: Adult; Biomarkers; Blood Coagulation; Blood Coagulation Disorders; Blood Transfusion; Cell-Derived Microparticles; Female; Hemorrhage; Humans; Injury Severity Score; Male; Middle Aged; Partial Thromboplastin Time; Phenotype; Predictive Value of Tests; Prospective Studies; Risk Factors; Thrombelastography; Thrombin; Thromboplastin; United States; Wounds and Injuries; Young Adult

Pharmaceutical grade heparins from porcine intestine and bovine lung consist mainly of repeating tri-sulfated units, of the disaccharide →4-α-IdoA2S-1→4-α-GlcNS6S-1→. Heparin preparations from bovine intestine, in contrast, are more heterogeneous. Nuclear magnetic resonance (NMR) and disaccharide analysis after heparinase digestions show that heparin from bovine intestine contains α-glucosamine with significant substitutive variations: 64% are 6-O-sulfated and N -sulfated, as in porcine intestinal heparin while 36% are 6-desulfated. Desulfated α-iduronic acid units are contained in slightly lower proportions in bovine than in porcine heparin. NMR data also indicate N-, 3- and 6-trisulfated α-glucosamine (lower proportions) and α-GlcNS-1→4-α-GlcA and α-IdoA2S-1→4-α-GlcNAc (higher amounts) in bovine than in porcine heparin. Porcine and bovine heparins can be fractionated by anion exchange chromatography into three fractions containing different substitutions on the α-glucosamine units. Each individual fraction shows close disaccharide composition and anticoagulant activity, regardless of their origin (bovine or porcine intestine). However, these two heparins differ markedly in the proportions of the three fractions. Interestingly, fractions with the typical heparin disaccharides of porcine intestine are present in bovine intestinal heparin. These fractions contain high in vitro anticoagulant activity, reduced antithrombotic effect and high bleeding tendency. These observations indicate that the prediction of haemostatic effects of heparin preparations cannot rely exclusively on structural analysis and anticoagulant assays in vitro . Minor structural components may account for variations on in vivo effects. In conclusion, we suggest that pharmaceutical grade bovine intestinal heparin, even after purification procedures, is not an equivalent drug to porcine intestinal heparin.

Topics: Animals; Anion Exchange Resins; Anticoagulants; Antithrombin Proteins; Blood Coagulation; Cattle; Chromatography, Ion Exchange; Disaccharides; Disease Models, Animal; Factor Xa; Factor Xa Inhibitors; Female; Fibrinolytic Agents; Glycosylation; Hemorrhage; Heparin; Heparin Antagonists; Heparin Lyase; Humans; Intestinal Mucosa; Magnetic Resonance Spectroscopy; Male; Molecular Structure; Partial Thromboplastin Time; Protamines; Prothrombin; Rats; Rats, Wistar; Structure-Activity Relationship; Sulfates; Swine; Thromboplastin; Venous Thrombosis

Systemic blockade of tissue factor (TF) attenuates acute lung injury (ALI) in animal models of sepsis but the effects of global TF deficiency are unknown. We used mice with complete knockout of mouse TF and low levels (∼1%) of human TF (LTF mice) to test the hypothesis that global TF deficiency attenuates lung inflammation in direct lung injury.. LTF mice were treated with 10 μg of lipopolysaccharide (LPS) or vehicle administered by direct intratracheal injection and studied at 24 h.. Contrary to our hypothesis, LTF mice had increased lung inflammation and injury as measured by bronchoalveolar lavage cell count (3.4×10(5) wild-type (WT) LPS vs 3.3×10(5) LTF LPS, p=0.947) and protein (493 μg/ml WT LPS vs 1014 μg/ml LTF LPS, p=0.006), proinflammatory cytokines (TNF-α, IL-10, IL-12, p<0.035 WT LPS vs LTF LPS) and histology compared with WT mice. LTF mice also had increased haemorrhage and free haemoglobin in the airspace accompanied by increased oxidant stress as measured by lipid peroxidation products (F(2) isoprostanes and isofurans).. These findings indicate that global TF deficiency does not confer protection in a direct lung injury model. Rather, TF deficiency causes increased intra-alveolar haemorrhage following LPS leading to increased lipid peroxidation. Strategies to globally inhibit TF may be deleterious in patients with ALI.

Topics: Acute Lung Injury; Analysis of Variance; Animals; Blotting, Western; Bronchoalveolar Lavage; Cytokines; Electrophoresis, Polyacrylamide Gel; Furans; Hemoglobins; Hemorrhage; Inflammation; Isoprostanes; Lipopolysaccharides; Mice; Mice, Knockout; Oxidative Stress; Pulmonary Alveoli; Real-Time Polymerase Chain Reaction; Statistics, Nonparametric; Thromboplastin

Tissue factor (TF) antagonists targeting the factor VII (FVII) binding domain have been shown to interrupt acute vascular thrombus formation without impairing haemostasis in non-human primates. In this study, we evaluate whether a human/mouse chimeric monoclonal antibody (ALT-836, formerly known as Sunol-cH36) blocking the factor X/factor IX (FX/FIX) binding site of tissue factor could achieve similar clinical benefits in an arterial thrombosis model induced by surgical endarterectomy in chimpanzees. In this model, sequential surgical endarterectomies on right and left superficial femoral arteries were performed 30 days apart in five chimpanzees. A bolus (1 mg/kg) of ALT-836 was injected intravenously immediately preceding the restoration of flow in the endarterectomised femoral artery. Pre-surgical labelling of autologous platelets using (111)In-Oxine and post-surgical gamma camera imaging of (111)In-platelet deposition at endarterectomy sites was performed. The manipulated arterial segments were harvested for patency analysis 30 days following surgery. The results indicate that ALT-836 was highly effective at reducing acute vascular thrombosis, with no significant variations in surgical blood loss and template-bleeding time in the treated group compared to the control animals. These data suggest that ALT-836 is an effective and safe antithrombotic agent in preventing TF-initiated vascular thrombogenesis without compromising haemostasis.

Topics: Animals; Antibodies, Monoclonal; Antibody Specificity; Binding Sites; Blood Coagulation; Blood Loss, Surgical; CHO Cells; Cricetinae; Cricetulus; Disease Models, Animal; Dose-Response Relationship, Drug; Endarterectomy; Factor IX; Factor VIIa; Factor X; Female; Femoral Artery; Fibrinolytic Agents; Hemorrhage; Humans; Injections, Intravenous; Mice; Mice, Inbred BALB C; Pan troglodytes; Radionuclide Imaging; Recombinant Fusion Proteins; Thromboplastin; Thrombosis

Increasing reports of bleeding and peri- or post-operative blood dyscrasias in Brazil were possibly associated with the use of heparin from bovine instead of porcine intestine. These two pharmaceutical grade heparins were analysed for potential differences. NMR analyses confirmed that porcine heparin is composed of mainly trisulfated disaccharides -->4-alpha-IdoA2S-1-->4-alpha-GlcNS6S-1-->. Heparin from bovine intestine is also composed of highly 2-sulfated alpha-iduronic acid residues, but the sulfation of the alpha-glucosamine units vary significantly: approximately 50% are 6- and N -disulfated, as in porcine heparin, while approximately 36% are 6-desulfated and approximately 14% N -acetylated. These heparins differ significantly in their effects on coagulation, thrombosis and bleeding. Bovine heparin acts mostly through factor Xa. Compared to porcine heparin on a weight basis, bovine heparin exhibited approximately half of the anticoagulant and antithrombotic effects, but similar effect on bleeding. These two heparins also differ in their protamine neutralisation curves. The doses of heparin from bovine intestine required for effective antithrombotic protection and the production of adverse bleeding effects are closer than those for porcine heparin. This observation may explain the increasing bleeding observed among Brazilian patients. Our results suggest that these two types of heparin are not equivalent drugs.

Topics: Animals; Blood Coagulation; Cattle; Disaccharides; Factor Xa; Hemorrhage; Heparin; Intestinal Mucosa; Nuclear Magnetic Resonance, Biomolecular; Protamines; Rats; Rats, Wistar; Swine; Thromboplastin; Venous Thrombosis

It has been recently demonstrated that a carbon monoxide releasing molecule (tricarbonyldichlororuthenium (II) dimer; CORM-2) enhances coagulation and attenuates vulnerability to fibrinolysis in normal and hemophiliac human plasma. We tested the hypothesis that plasma obtained from warfarin-treated subjects would demonstrate improved coagulation and decreased fibrinolytic vulnerability following exposure to CORM-2.. Anonymous donor plasma samples with international normalized ratios (INR) values ranging from 1.5-5.4 were exposed to 0 or 100 microM CORM-2 and activated with tissue factor (12 samples). Additional samples within the same INR range were exposed to 0 or 100 microM CORM-2 and 0 or 100 U/ml tissue-type plasminogen activator (tPA) to assess fibrinolytic vulnerability (8 samples). Thrombelastographic data were collected until either clot strength stabilized or clot lysis occurred as appropriate.. In the absence of tPA, all but one sample (INR=1.5) demonstrated a marked increase in the velocity of clot formation (40-577%) and strength (42-180%) following CORM-2 exposure. Of interest, in the presence of tPA, all samples (including the previously unresponsive sample) were noted to have an increase in the velocity of clot formation and strength, coupled with a prolonged onset to maximal rate of clot lysis (60-242%) and increased clot lysis time (74-149%). As with normal and hemophilic plasma, both enhancement of coagulation and attenuation of fibrinolysis occur following CORM-2 exposure in plasma from warfarin-treated subjects. Future investigation must determine if carbon monoxide releasing molecules could be used therapeutically to control bleeding in warfarin-treated patients.

Topics: Blood Coagulation; Carbon Monoxide; Fibrinolysis; Hemorrhage; Humans; International Normalized Ratio; Organometallic Compounds; Plasma; Plasminogen Activators; Thrombelastography; Thromboplastin; Thrombosis; Tissue Plasminogen Activator; Warfarin

Topics: Administration, Oral; Blood Coagulation; Blood Coagulation Tests; Clinical Chemistry Tests; Fibrinolytic Agents; Hemorrhage; Humans; International Normalized Ratio; Safety; Stroke; Thrombin; Thromboplastin; Venous Thrombosis

Thrombin amplifies the blood coagulation via factor V (FV)-mediated positive feedback loop. We hypothesised that factor Xa (FXa) inhibitors would interfere more gradually with this feedback activation loop than thrombin inhibitors, thereby achieving a better balance between haemostasis and prevention of thrombosis. In this study, we compared the effects of TAK-442, a novel FXa inhibitor, versus ximelagatran, a thrombin inhibitor, on FV-mediated positive feedback, venous thrombosis and bleeding. In normal plasma, TAK-442 delayed the onset of tissue factor-induced thrombin generation and prolonged prothrombin time (PT) with more gradual concentration-response curve than melagatran, the active form of ximelagatran. The effect of melagatran on the onset of thrombin generation decreased in an FVa-concentration-dependent manner in FV-deficient plasma supplemented with FVa. Furthermore, in FV-deficient plasma, the PT-prolonging potency of melagatran was markedly increased with a change in its concentration-response curve from steep to gradual. In the rat venous thrombosis model, TAK-442 (10 mg/kg, p.o.) prevented thrombus formation by 55% with 1.2 times prolongation of PT; a similar effect was observed in ximelagatran-treated (3 mg/kg, p.o.) rats. TAK-442 at 100 mg/kg prolonged PT by only 2.1 times with no change in bleeding time (BT), whereas ximelagatran at 10 mg/kg prolonged PT by 3.9 times and significantly increased BT. These results suggest that the differential effects of the two agents on FV-mediated amplification of thrombin generation may underlie the observation of a wider therapeutic window for TAK-442 than for ximelagatran.

Topics: Administration, Oral; Animals; Anticoagulants; Antithrombins; Azetidines; Benzylamines; Blood Coagulation; Disease Models, Animal; Dose-Response Relationship, Drug; Factor V; Factor Xa; Factor Xa Inhibitors; Feedback, Physiological; Hemorrhage; Humans; Male; Phospholipids; Prothrombin Time; Pyrimidinones; Rats; Rats, Sprague-Dawley; Risk Assessment; Sulfones; Thrombin; Thromboplastin; Venous Thrombosis

Topics: Animals; Cell Movement; Factor VIIa; Genetic Predisposition to Disease; Hemophilia A; Hemorrhage; Inflammation; Leukocytes; Mice; Mice, Inbred C57BL; Recombinant Proteins; Thrombocytopenia; Thromboplastin; Wound Healing

Bovine topical thrombin is commonly used for local hemostasis in pediatric surgery. Acquired inhibitors to coagulation factors, particularly to factor V and bovine thrombin, have been infrequently reported in the pediatric population. We report a 3-year-old male who developed a coagulopathy and clinical bleeding after cardiothoracic surgery, during which bovine topical thrombin was used for local hemostasis. Laboratory tests revealed elevated prothrombin, partial thromboplastin, and thrombin times, and a low factor V activity level. He was found to have both human-thrombin and factor V inhibitors, among the first reported cases of these combined inhibitors secondary to bovine topical thrombin. He was treated with intravenous immunoglobulin and steroids with a rapid and durable response.

Topics: Administration, Topical; Animals; Blood Coagulation Disorders; Blood Coagulation Factors; Cattle; Child, Preschool; Factor V; Hemorrhage; Humans; Immunoglobulin G; Immunoglobulins, Intravenous; Male; Prognosis; Prothrombin Time; Thrombin; Thrombin Time; Thromboplastin

The coagulation "cascade" model accurately represents the mechanisms of the prothrombin time and activated partial thromboplastin time tests. However, these tests and the "cascade" model do not accurately reflect the risk of hemorrhage or thrombosis in vivo. In hepatic insufficiency, a balanced reduction in the levels of most of pro- and anticoagulant proteins produced in the liver does not impair thrombin generation until levels are quite low. However, the ability of the coagulation system to tolerate or recover from an insult is markedly impaired in liver disease. This allows the coagulation system to be more easily tipped into a state favoring either hemorrhage or thrombosis.

Topics: Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Platelets; Hemorrhage; Hemostasis; Humans; Liver Cirrhosis; Liver Failure; Models, Biological; Prothrombin Time; Thrombin; Thromboplastin; Thrombosis

Haemophilia A displays phenotypic heterogeneity with respect to clinical severity. The aim of this study was to determine if tissue factor (TF)-initiated thrombin generation profiles in whole blood in the presence of corn trypsin inhibitor (CTI) are predictive of bleeding risk in haemophilia A. We studied factor(F) VIII deficient individuals (11 mild, 4 moderate and 12 severe) with a well-characterized 5-year bleeding history that included haemarthrosis, soft tissue haematoma and annual FVIII concentrate usage. This clinical information was used to generate a bleeding score. The bleeding scores (range 0-32) were separated into three groups (bleeding score groupings: 0, 0 and < or = 9.6, >9.6), with the higher bleeding tendency having a higher score. Whole blood collected by phlebotomy and contact pathway suppressed by 100 microg mL(-1) CTI was stimulated to react by the addition of 5 pM TF. Reactions were quenched at 20 min by inhibitors. Thrombin generation, determined by enzyme-linked immunosorbent assay for thrombin-antithrombin was evaluated in terms of clot time (CT), maximum level (MaxL) and maximum rate (MaxR) and compared to the bleeding score. Data are shown as the mean+/-SD. MaxL was significantly different (P < 0.001) between the groups: 504 +/- 114, 315 +/- 117 and 194 +/- 91 nM; with higher thrombin concentrations in the groups with lower bleeding scores. MaxR was higher in the groups with a lower bleeding score; 97 +/- 51, 86 +/- 60 and 39 +/- 16 nM min(-1) (P = 0.09). No significant difference was detected in CT among the groups, 5.6 +/- 1.3, 4.7 +/- 0.7 and 5.6 +/- 1.3 min. Our empirical study in CTI-inhibited whole blood shows that the MaxL of thrombin generation appears to correlate with the bleeding phenotype of haemophilia A.

Topics: Enzyme-Linked Immunosorbent Assay; Hemophilia A; Hemorrhage; Humans; Male; Phenotype; Plant Proteins; Reference Values; Thrombin; Thromboplastin; Whole Blood Coagulation Time

To gain insight into the contribution of platelet-dependent thrombin formation in haemostasis and thrombosis, we investigated under flow conditions the haemostatic functions of platelets from a patient with Scott syndrome. Scott platelets are characterised by a diminished platelet-dependent thrombin generation. Thrombin generation was determined by calibrated automated thrombography and flow-based experiments were performed to reveal collagen-mediated platelet activation and fibrin deposition. Our studies indicate that adherent Scott platelets do not differ from control platelets in the formation of stable platelet aggregates under static and flow conditions. While for adherent control platelets a shape change, e.g. balloon formation, and externalisation of phosphatidylserine (PS) is associated with an increase in intracellular calcium concentration, this is not the case for Scott platelets. The calcium-induced morphological changes in control platelets are accompanied with a diminished recruitment of free flowing platelets. Scott platelets, not showing a calcium-induced shape change, also lost the ability to recruit free flowing platelets. These findings rebut the hypothesis that the mild bleeding tendency of Scott syndrome patients is due to a preserved adhesive activity of patient's platelets. Perfusion of tissue factor (TF)-activated control blood over immobilised collagen results in the formation of fibrin fibers that radiate from platelet aggregates. Although platelet aggregates were also observed after perfusion with TF-activated Scott blood, fibrin deposition was not observed. In conclusion, our findings indicate that platelet adhesion and spreading on a collagen matrix in the absence of fibrin formation is sufficient to sustain haemostasis under non-traumatic conditions.

Topics: Blood Coagulation; Blood Coagulation Disorders; Blood Platelets; Calcium; Female; Fibrin; Hemorrhage; Humans; Middle Aged; Platelet Aggregation; Regional Blood Flow; Syndrome; Thrombin; Thromboplastin

Tissue factor (TF) is expressed widely at the subluminal surface of blood vessels and serves as the primary cellular initiator of the extrinsic pathway of blood coagulation. Lack of TF in mice resulted in lethality in utero, but human TF (huTF) expressed at low levels from a human minigene rescued null mice from prenatal death. Although these low-TF expressing transgenic mice developed to term, they had a significantly shorter life span and exhibited hemorrhage and fibrosis in the heart.. Human TF knock-in (TFKI) mice were generated by replacing the first two exons of the mouse (murine) TF (muTF) gene with the huTF complete coding sequence, thus placing it under the control of the endogenous muTF promoter.. Expression of huTF in the TFKI mice was similar to muTF in wild-type (wt) mice. The TFKI mice showed no microscopic evidence of spontaneous hemorrhage in the heart, nor cardiac fibrosis at up to 18 months of age. Immunohistochemistry showed that huTF was expressed in cells surrounding blood vessels in TFKI mice. Coagulation activity of brain homogenates from TFKI mice was comparable with that from wt brain. Cardiac hemorrhage similar to that of the low-TF transgenic mice occurred in the TFKI mice when huTF was blocked by a neutralizing anti-huTF monoclonal antibody.. We generated a transgenic mouse line that expresses huTF under the control of the endogenous muTF promoter at physiological levels. Our results suggest that huTF can fully reconstitute the murine coagulation system and mediate normal hemostasis.

Topics: Animals; Antibodies, Monoclonal; Brain; Cardiomyopathies; Epitopes; Female; Gene Expression Regulation; Genes, Synthetic; Hemorrhage; Hemostasis; Humans; Immunoglobulin G; Kidney; Male; Mice; Mice, Knockout; Mice, Transgenic; Myocardium; Organ Specificity; Pericytes; Regulatory Sequences, Nucleic Acid; Species Specificity; Thromboplastin

Topics: Animals; Antibodies, Monoclonal; Epitopes; Factor VIIa; Gene Expression; Hemorrhage; Hemostasis; Humans; Immunoglobulin G; Kidney; Mice; Mice, Knockout; Mice, Transgenic; Myocardium; Organ Specificity; Regulatory Sequences, Nucleic Acid; Species Specificity; Thromboplastin

The function of tissue factor (Tf)-initiated coagulation is hemorrhage control through the formation and maintenance of an impermeable platelet-fibrin barrier. The catalytic processes involved in the clot maintenance function are not well defined, although the rebleeding problems characteristic of individuals with hemophilias A and B suggest a link between specific defects in the Tf-initiated process and defects in the maintenance function. We have previously demonstrated, using a methodology of "flow replacement" (or resupply) of ongoing Tf-initiated reactions with fresh reactants, that procoagulant complexes are produced during Tf-initiated coagulation, which are capable of reinitiating coagulation without input from extrinsic factor Xase activity (Orfeo, T., Butenas, S., Brummel-Ziedins, K. E., and Mann, K. G. (2005) J. Biol. Chem. 280, 42887-42896). Here we used Tf-initiated reactions in normal and hemophilia blood or in their corresponding proteome mixtures as sources of procoagulant end products and then varied the resupplying material to determine the identity of the catalysts that drive the new cycle of thrombin formation. The central findings are as follows: 1) the prothrombinase complex (fVa-fXa-Ca(2+)-membrane) accumulated during the episode of Tf-initiated coagulation is the primary catalyst responsible for the observed pattern of prothrombin activation after resupply; 2) impairments in intrinsic factor Xase function, i.e. hemophilias A and B, result in an impaired capacity to mount a resupply response; and 3) in normal hemostasis the intrinsic factor Xase function contributes to the durability of the resupply response.

Topics: Adult; Blood Coagulation; Factor V; Factor X; Factor Xa; Hemophilia A; Hemophilia B; Hemorrhage; Hemostasis; Humans; Male; Proteome; Thromboplastin

The thrombin generation test is used to study coagulation in patients with haemorrhagic diseases or with high thrombotic risk. To our knowledge, this is the first study investigating the relative influence of coagulation factors on thrombin generation in plasma. The aim was to investigate the influence of coagulant factors, anticoagulant factors, and tissue factor (TF) on three parameters: endogenous thrombin potential (ETP), peak thrombin concentration, and lag time for the appearance of thrombin. At a low TF concentration, all factors except factor XI influenced thrombin generation. At a high TF concentration, only the factors of the extrinsic pathway exerted an influence. ETP and peak thrombin were linearly correlated to factor II concentration. Factor V and factor VII effects increased hyperbolically with factor concentration. The influence of factor X on thrombin generation depended on TF concentration. In the absence of factor VIII and factor IX, ETP fell to 60-70% of the normal when peak thrombin fell to 25-30% of the normal. Fibrinogen concentration influenced ETP and peak thrombin and decreasing fibrinogen levels shortened the lag time. As expected, decreasing antithrombin concentration caused dramatic increases in thrombin generation. Protein S prolonged the lag time, especially at a low TF concentration. No effect of protein C was observed, likely due to the absence of thrombomodulin. The thrombin generation test was more sensitive to factor deficiencies at low than at high TF concentration. ETP was not the most critical parameter for studying coagulation factor deficiencies. Instead, peak thrombin was the most sensitive parameter.

Topics: Blood Coagulation Factors; Blood Coagulation Tests; Coagulation Protein Disorders; Hemorrhage; Humans; Sensitivity and Specificity; Thrombin; Thromboplastin; Thrombosis

Therapeutic use of unfractionated heparin and low molecular weight heparins (LMWHs) is limited by hemorrhagic adverse effects. We compared the antithrombotic effect of LMW fucoidan (LMWF) and LMWH in an experimental model.. Thrombosis was induced in femoral arteries of male New Zealand White rabbits by in situ induction of endothelial apoptosis with staurosporine (10(-5)M for 30 min). Starting the day before apoptosis induction, the animals received subcutaneous LMWF (15 mg/kg), LMWH (enoxaparin 2.5 mg/kg) or saline solution (control group) twice a day for 4 days.. The degrees of apoptosis and endothelial denudation were similar in the 3 groups. The thrombotic score was significantly lower in the LMWF group than in the LMWH and control groups (p = 0.01). Tissue factor expression was significantly lower in the LMWF group than in the control and LMWH groups (p = 0.01). The plasma concentration of tissue factor pathway inhibitor was significantly increased after LMWF injection (137 +/- 28 vs. 102 +/- 17; p = 0.01), whereas no change was observed after LMWH treatment. LMWF did not prolong the bleeding time or decrease platelet aggregation.. LMWF appeared to be more effective than LMWH for preventing arterial thrombosis in this experimental model. LMWF also had a lower hemorrhagic risk than LMWH.

Topics: Animals; Apoptosis; Blood Coagulation; Disease Models, Animal; Dose-Response Relationship, Drug; Femoral Artery; Fibrinolytic Agents; Hemorrhage; Heparin, Low-Molecular-Weight; Lipoproteins; Male; Platelet Aggregation; Polysaccharides; Rabbits; Staurosporine; Thromboplastin; Thrombosis

Current anticoagulant therapies for the prevention and treatment of thromboembolic disorders have many drawbacks: vitamin K antagonists interact with food and drugs and require frequent laboratory monitoring, and heparins require parenteral administration. Oral rivaroxaban (BAY 597939) is a new, highly selective and potent direct factor-Xa (FXa) inhibitor with a predictable pharmacodynamic and pharmacokinetic profile and could therefore be an attractive antithrombotic drug. It was the objective of this study to investigate the antithrombotic efficacy of oral rivaroxaban in two rabbit models of experimental venous thrombosis. In the venous stasis (prevention) model, animals were randomized to receive oral rivaroxaban 0.3, 1.0, 3.0 or 10.0 mg/kg or vehicle control. Thrombosis was induced by jugular vein stasis and injection of thromboplastin into the ear vein. In the venous thrombosis (treatment) model, intravenous (1.0 and 3.0 mg/kg) and oral (3.0 mg/kg) rivaroxaban was compared with intravenous nadroparin (40 U bolus and 20 U/h), fondaparinux (42 microg/kg) and vehicle control. Thrombus growth was assessed by measuring the accretion of radiolabelled fibrinogen into preformed clots in the jugular veins. Bleeding was assessed using an ear bleeding model. In the prevention model, rivaroxaban reduced thrombus formation dose-dependently (calculated ED(50) 1.3 mg/kg). In the treatment model, oral rivaroxaban (3.0 mg/kg) reduced thrombus growth to a similar extent to intravenous rivaroxaban (1.0 mg/kg), nadroparin and fondaparinux. Oral rivaroxaban did not prolong bleeding time. In conclusion, the orally available selective, direct FXa inhibitor rivaroxaban is effective in the prevention and treatment of venous thrombosis in two well-established models of experimental thrombosis.

Topics: Administration, Oral; Animals; Anticoagulants; Blood Coagulation Tests; Disease Models, Animal; Dose-Response Relationship, Drug; Factor Xa Inhibitors; Fibrinolytic Agents; Fondaparinux; Hemorrhage; Humans; Infusions, Intravenous; Injections, Intravenous; Jugular Veins; Ligation; Morpholines; Nadroparin; Polysaccharides; Rabbits; Random Allocation; Rivaroxaban; Thiophenes; Thromboplastin; Venous Thrombosis

Topics: Antifibrinolytic Agents; Brain Injuries; Disseminated Intravascular Coagulation; Hemorrhage; Humans; Thromboplastin

Topics: Blood Coagulation; Blood Platelets; Factor VII; Hemorrhage; Humans; Thrombin; Thromboplastin; Thrombosis

Tissue factor (TF) initiates blood coagulation, but its expression in the vascular space requires a finite period of time. We hypothesized that targeting exogenous tissue factor to sites of vascular injury could lead to accelerated hemostasis. Since phosphatidylserine (PS) is exposed on activated cells at sites of vascular injury, we cloned the cDNA for a chimeric protein consisting of the extracellular domain of TF (called soluble TF or sTF) and annexin V, a human PS-binding protein. Both the sTF and annexin V domains had ligand-binding activities consistent with their native counterparts, and the chimera accelerated factor X activation by factor VIIa. The chimera exhibited biphasic effects upon blood coagulation. At low concentrations it accelerated blood coagulation, while at higher concentrations it acted as an anticoagulant. The chimera accelerated coagulation in the presence of either unfractionated or low-molecular-weight heparins more potently than factor VIIa and shortened the bleeding time of mice treated with enoxaparin. The sTF-annexin V chimera is a targeted procoagulant protein that may be useful in accelerating thrombin generation where PS is exposed to the vasculature, such as may occur at sites of vascular injury or within the vasculature of tumors.

Topics: Animals; Annexin A5; Anticoagulants; Blood Coagulation; Blood Vessels; Coagulants; Dose-Response Relationship, Drug; Factor VIIIa; Factor X; Hemorrhage; Heparin, Low-Molecular-Weight; Humans; Mice; Neoplasms; Neovascularization, Pathologic; Phosphatidylserines; Protein Structure, Tertiary; Recombinant Fusion Proteins; Thromboplastin

We previously reported that the targeted disruption of murine antithrombin (AT) gene resulted in embryonic lethality before 16.5 gestational days (gd) because of severe cardiac and hepatic thrombosis.. To investigate the influences of lowered tissue factor (TF) activity upon hypercoagulation of AT-/- embryos, we crossed AT+/- with low TF (mTF-/- hTF+) mice to yield homozygous AT-deficient mice with the extremely low TF activity, that is expressed from the inserted human TF mini gene.. AT-/- embryos either with 50% TF (AT-/- mTF+/- hTF+) or with low (approximately 1% TF, AT-/- mTF-/- hTF+) were not born, although the survival was prolonged until 18.5 gd. In both genotypes, histological examination showed disseminated thrombosis in hepatic sinusoidal space or in the portal veins, suggesting that the thrombogenesis caused loss of hepatic blood flow. As in original AT-/-, AT-/- mTF+/- hTF+ showed subcutaneous (s.c.) bleeding and also suffered from the myocardial degeneration apparently because of coronary thrombus formation. However, AT-/- mTF-/- hTF+ had no skin hemorrhage and the thrombosis and degeneration were completely abolished in the heart. Myocardium of adult low TF mice had exhibited fibrosis secondary to hemorrhage; however, it was significantly decreased in low TF mice with AT+/-.. Our current model suggests that, in the heart, TF plays an important role in the thrombogenesis and it counterbalances AT-dependent anticoagulation. AT may be a potent anticoagulant during mice development and the activation and subsequent regulation of TF-procoagulant activity take place differently between the liver and the heart. These differences appear to point to local regulatory mechanisms in murine hemostasis.

Topics: Animals; Antithrombin III; Budd-Chiari Syndrome; Coronary Thrombosis; Embryo, Mammalian; Hemorrhage; Hemostasis; Humans; Liver; Mice; Mice, Knockout; Mice, Transgenic; Myocardium; Thromboplastin; Thrombosis

Inactivation of the murine tissue factor (TF) gene or tissue factor pathway inhibitor 1 (TFPI) gene results in embryonic lethality, indicating that both are required for embryonic development. We have shown that expression of low levels of TF from a transgene (hTF) rescues TF-null embryos. However, low-TF mice (mTF(-/-)/hTF+) have hemostatic defects in the uterus, placenta, heart, and lung. In this study, we hypothesized that the death of TFPI-/- embryos was due to unregulated TF/FVIIa activity and that the hemostatic defects in low-TF mice were due to insufficient TF expression. Therefore, we attempted to rescue TFPI-/- embryos by reducing TF expression, and to restore hemostasis in low-TF mice by abolishing TFPI expression. Intercrossing TFPI(+/-)/mTF(+/-)/hTF+/- mice generated close to the expected number of TFPI(-/-)/low-TF mice at weaning age from 128 offspring, indicating rescue of TFPI-/- embryos from embryonic lethality. Conversely, a decrease in TFPI levels dose-dependently prolonged the survival of low-TF mice and rescued the hemorrhagic defects in the lung and placenta but not in the heart or uterus. These results indicate that the correct balance between TF and TFPI in different organs is required to maintain hemostasis during embryonic development and in adult mice.

Topics: Age Factors; Animals; Coronary Circulation; Embryonic Development; Female; Gene Expression Regulation, Developmental; Heart; Hemorrhage; Hemostasis; Lipoproteins; Lung; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Placenta; Pregnancy; Pulmonary Circulation; RNA, Messenger; Survival Rate; Thromboplastin; Uterus

Tissue factor (TF) is believed to play an important role in coagulation, inflammation, angiogenesis and wound healing as well as in tumor growth and metastasis. To facilitate in vivo studies in experimental murine models, we have produced recombinant murine factor VII (FVII) and the ectodomain of murine TF, TF(1-223). Murine FVII was activated to FVIIa with human factor Xa and upon reaction with FFR-chloromethyl ketone converted into an active site-blocked TF antagonist, FFR-FVIIa. The activity of murine FVIIa was characterized in factor X activation assays as well as in clot assays with murine and human thromboplastin in murine and human plasma. In these assays murine FVIIa exhibited a specific activity equivalent to or higher than human FVIIa. Further analysis showed that murine FVIIa binds with high affinity to both murine and human TF, whereas the association of human FVIIa to murine TF is about three orders of magnitude weaker than the association to human TF. This difference was further emphasized by the effect of murine-and human FFR-FVIIa on bleeding in an in vivo mouse model. Intra-peritoneal administration of 1 mg/kg murine FFR-FVIIa significantly prolonged the tail-bleeding time, whereas no effect on bleeding was observed with a 25-times higher dose of the human FFR-FVIIa. Together, these data confirms the notion of poor species compatibility between human FVII and murine TF and emphasizes the requirement for autologous FVIIa in studies on the role of the TF in experimental in vivo pharmacology.

Topics: Animals; Binding Sites; Cloning, Molecular; Factor VIIa; Hemorrhage; Humans; Mice; Models, Animal; Recombinant Proteins; Species Specificity; Thromboplastin

This paper presents an analysis of 24 cases in which recombinant factor VIIa (rFVIIa) was used in the management of hemorrhage in patients with thrombocytopenia associated with hematologic malignancies. This is the largest case aggregation to date and focuses on preliminary experience in the off-label use of this hemostatic agent. Data were extracted from the international, Internet-based registry, www.haemostasis.com, accessed in September 2003. The search results were manually cross-checked against monthly summary reports. The physicians providing the cases were contacted individually to approve the use of their cases, supply any information missing from the database, and validate the data already held. Patients with acute myeloid leukemia, acute lymphoblastic leukemia, Hodgkin's disease, non-Hodgkin's lymphoma, Burkitt's lymphoma, B-cell or T-cell lymphoma, or aplastic anemia received rFVIIa at total doses of between 18 and 1040 mug/kg body weight. Bleeding stopped in 11 of 24 (46%) patients, markedly decreased in 8 of 24 (33%) patients, and decreased in 4 of 24 (17%) patients. In most patients, the response was achieved within 2.5 hours of administration of rFVIIa. The use of rFVIIa was generally well tolerated -- 1 case of ischemic stroke was considered to be possibly related to rFVIIa administration, but this has yet to be confirmed. A review of these 24 cases submitted to the www.haemostasis.com database suggests that rFVIIa is beneficial in the management of hemorrhage in patients with thrombocytopenia and hematologic malignancies. This warrants further investigation in rigorously controlled clinical trials.

Topics: Adolescent; Adult; Anticoagulants; Child; Child, Preschool; Factor VIIa; Female; Hemorrhage; Humans; Internet; Leukemia; Lymphoma; Male; Medical Audit; Middle Aged; Prothrombin; Thrombocytopenia; Thromboplastin

This study in non-human primates was designed to evaluate the bleeding propensity of a selective, small molecule inhibitor of tissue factor (TF)/VIIa in combination with acetylsalicylic acid (ASA) in comparison to the combination of ASA and warfarin. Bleeding time was increased by ASA but was not prolonged further by the addition of the TF/VIIa inhibitor, PHA-927, at doses that elevated the prothrombin time to 8-fold. In contrast, bleeding time was prolonged by warfarin alone and further exacerbated by the presence of ASA. Acute blood loss at the bleeding site, while not significantly increased by either warfarin or PHA-927, was increased substantially in several individuals treated with a combination of warfarin and ASA but not by the combination of TF/VIIa inhibitor and ASA. These data predict that TF/VIIa inhibition, in the presence of chronic aspirin therapy in patients with cardiovascular risk factors, will be a safe therapy for thrombotic disorders.

Topics: Aminobenzoates; Animals; Anticoagulants; Aspirin; Bleeding Time; Dose-Response Relationship, Drug; Drug Combinations; Factor VIIa; Hemorrhage; Macaca fascicularis; Male; Platelet Aggregation Inhibitors; Prothrombin Time; Pyrazines; Thromboplastin; Warfarin; Whole Blood Coagulation Time

Abnormal uterine bleeding is the major reason for discontinuing long-term progesterone-only contraceptives (LTPOCs). Prior studies demonstrated that endometria exposed to the LTPOC, Norplant, display aberrant angiogenesis, leukocyte infiltration, and hypoxia-associated impaired blood flow. Paradoxically, human endometrial stromal cells (HESCs) of these specimens exhibit elevated expression of tissue factor (TF), the primary initiator of hemostasis via thrombin generation. The current study demonstrates that TF levels are also elevated in HESCs that are decidualized after insertion of Mirena, an intrauterine system that releases levonorgestrel directly into the endometrial canal and produces elevated perivascular levels of the proinflammatory and angiognenic cytokine IL-8. Because bleeding, inflammation, and ischemia-associated increased vascular permeability enhance access of plasma factor VII to HESC-expressed TF to generate thrombin, we evaluated the effects of steroids, thrombin, and hypoxia on HESC expression of IL-8. Confluent HESCs were incubated in a serum-containing medium for 7 d with vehicle control or estradiol (E(2)) plus medroxyprogesterone acetate (MPA). The medium was then exchanged for corresponding defined medium with and without thrombin, and the cultures were incubated in parallel for up to 48 h in a standard incubator (normoxia) or a sealed chamber at 0-1% O(2) (hypoxia). Under normoxia, immunoreactive IL-8 levels in the conditioned medium were reduced to one-third of control levels during decidualization with E(2)+MPA (P < 0.05; n = 5). In E(2)+MPA-treated cultures, thrombin (0.1 U/ml to 2.5 U/m) elicited a dose-dependent reversal of this inhibition, elevating IL-8 up to 60-fold (P < 0.05; n = 5) for more than 24 h and steady-state IL-8 mRNA levels by 3-fold for 3 h. The specific inactivator, hirudin, blocked most of the effects of thrombin, whereas TRAP-14, an agonist of the protease-activated receptor for thrombin, enhanced IL-8 output. In the absence of thrombin, hypoxia elevated IL-8 output 5-fold in E(2)+MPA-treated HESCs (P < 0.02, n = 4), with thrombin exerting additive effects. In contrast to its effects in progestin-treated HESCs, hypoxia did not elevate IL-8 output in control cultures. This study suggests that inhibition of IL-8 expression in decidualized HESCs contributes to the antiinflammatory milieu of the luteal phase. However, LTPOC-induced hypoxia and excess thrombin generation enhance IL-8 expression in decidualized

Topics: Cells, Cultured; Contraceptive Agents, Female; Decidua; Female; Gene Expression; Hemorrhage; Hemostatics; Humans; Hypoxia; In Vitro Techniques; Interleukin-8; Intrauterine Devices; Pregnancy; Pregnancy Trimester, First; Progesterone; RNA, Messenger; Stromal Cells; Thrombin; Thromboplastin

After an intravascular injection, adenoviral vectors are normally taken up by the reticuloendothelial system in the liver, where they rapidly trigger an innate response. However, we have previously found that the biodistribution of adenoviral vectors is altered in cirrhotic rats due to the presence of pulmonary intravascular macrophages, which cause a shift in vector uptake from the liver to the lungs. We now report that this is correlated with fatal pulmonary hemorrhagic edema in cirrhotic rats. In addition, cirrhotic rats reacted to vector with enormous increases in TNF-alpha and IL-6 and markedly prolonged coagulation times. Although we also saw fatal reactions to high doses of adenoviral vectors in normal rats, the time course and symptoms were very different, and pulmonary hemorrhagic edema was seen only in cirrhotic rats. Because abnormal pulmonary reticuloendothelial uptake is known to occur in humans during cirrhosis and other diseases, there is the potential that intravascular administration of adenoviral vectors might cause lung pathology in such patients.

Topics: Adenoviridae; Animals; Genetic Therapy; Genetic Vectors; Hemorrhage; Injections, Intravenous; Interleukin-6; Liver Cirrhosis, Experimental; Lung; Macrophages, Alveolar; Mononuclear Phagocyte System; Prothrombin; Pulmonary Edema; Rats; Rats, Sprague-Dawley; Thromboplastin; Tumor Necrosis Factor-alpha

We measured the plasma level of fibrinogen in 560 patients with disseminated intravascular coagulation (DIC) and evaluated its relationship with outcome and with other hemostatic markers. Forty-seven percent of patients had >200 mg/dL of plasma fibrinogen and 24% had <100 mg/dl of plasma fibrinogen, suggesting that plasma fibrinogen level is not a sensitive marker for DIC. In our analysis of outcome and plasma fibrinogen levels, the rate of death was high in leukemia/lymphoma patients with high fibrinogen concentration, but no significant difference in outcome was observed in relation to plasma fibrinogen concentration in non-leukemia/lymphoma patients with DIC. Among patients with leukemia/lymphoma, the frequency of organ failure was markedly high in patients with high plasma levels of fibrinogen. Among patients without leukemia/lymphoma, the frequency of organ failure increased concomitantly with the increase in plasma fibrinogen levels. The international normalized ratio was significantly increased in leukemia/lymphoma patients with low fibrinogen. FDP levels were slightly increased in patients with low fibrinogen. Platelet count was significantly low in patients without leukemia/lymphoma with high fibrinogen. DIC score increased concomitantly with the reduction in plasma fibrinogen levels. Plasma levels of thrombomodulin and tissue factor were significantly high in patients with high fibrinogen levels. Plasma levels of antiplasmin and plasminogen were significantly decreased in patients with low fibrinogen. Plasma levels of plasmin plasmin-inhibitor complex and tissue type plasminogen activator/plasminogen activator inhibitor-1 complex (PAI-I) were significantly higher in patients with low fibrinogen than in those with high fibrinogen. Plasma levels of PAI-I and IL-6 were significantly higher in patients with high fibrinogen than in those with low fibrinogen. Patients with high fibrinogen levels showed less activation of secondary fibrinolysis, which might explain the occurrence of organ failure and poor outcome.

Topics: Adult; Aged; alpha-2-Antiplasmin; Antifibrinolytic Agents; Antithrombin III; Biomarkers; Disseminated Intravascular Coagulation; Female; Fibrin Fibrinogen Degradation Products; Fibrinogen; Fibrinolysin; Fibrinolysis; Hematologic Neoplasms; Hemorrhage; Humans; Infections; Interleukin-1; Interleukin-6; International Normalized Ratio; Male; Middle Aged; Multiple Organ Failure; Neoplasms; Peptide Hydrolases; Plasminogen; Plasminogen Activator Inhibitor 1; Platelet Count; Prognosis; Thrombomodulin; Thromboplastin; Thrombosis; Tissue Plasminogen Activator

Impaired haemostasis is common in patients with end-stage renal disease, and may cause either thrombotic or bleeding complications. The purpose of this study was to assess whether plasma markers of coagulation activation in patients undergoing chronic haemodialysis (HD) can identify high-risk individuals, and to test the relevancy of type of vascular access or dialysis filter. We measured plasma levels of prothrombin fragment 1+2, fibrin D-dimers and tissue factor in 82 HD patients before and after dialysis. Clinical endpoints during the year following blood sampling were thrombosis in blood access, changes in blood access, other thromboembolic events, bleeding complications, ischaemic vascular disease, or death. We found elevated baseline levels of all three parameters in HD patients, compared to normal reference ranges. Plasma levels of all parameters (particularly fibrin D-dimers) were significantly higher in patients with prosthetic grafts and central venous dialysis catheters than in patients with native vessels. Patients with AV-fistulas or grafts who had bleeding complications (n=7) had significantly higher plasma levels of fibrin D-dimer and prothrombin fragment 1+2. Bleeding complications also occurred more frequently among the patients with prosthetic grafts (3/18) or central venous dialysis catheters (3/11) compared with those with grafts from native vessels (1/53). Other than a bleeding tendency, our data do no show any correlation between coagulation parameters and other clinical complications during haemodialysis. In conclusion, we found elevated plasma levels of markers of coagulation activation among HD patients. High levels of D-dimers and prothrombin fragment 1+2 correlated to bleeding diathesis instead of thromboembolism, and this tendency was most pronounced in patients with prosthetic grafts.

Topics: Aged; Catheters, Indwelling; Female; Fibrin Fibrinogen Degradation Products; Hemorrhage; Humans; Kidney Failure, Chronic; Male; Middle Aged; Peptide Fragments; Prostheses and Implants; Prothrombin; Reference Values; Renal Dialysis; Thromboplastin; Thrombosis; Ultrafiltration

Recombinant coagulation factor VIIa (rFVIIa) is generally accepted for treatment of patients with inhibitor-complicated hemophilia. Recently, rFVIIa variants with a specific enhancement of the tissue factor (TF)-independent proteolytic activity have been described.. The procoagulant and [thrombin-activatable fibrinolysis inhibitor (TAFI)-dependent] antifibrinolytic potentials of two superactive rFVIIa variants were compared with those of wild-type rFVIIa in a hemophilic setting.. Clot lysis assays were performed in plasma from six patients with inhibitor-complicated hemophilia A or in antibody-induced factor VIII-deficient platelet-rich plasma in the presence of different concentrations of the rFVIIa variants.. In the plasma model, M298Q-rFVIIa had a moderately increased procoagulant and antifibrinolytic potential, whereas V158D/E296V/M298Q/K337A-rFVIIa had a strongly increased procoagulant and antifibrinolytic activity compared with wild-type rFVIIa. The increased antifibrinolytic potential of the rFVIIa variants was completely dependent on enhancement of TAFI activation. In the platelet-rich plasma model similar results were obtained. The presence of TF was mandatory for clot formation in the absence of exogenous rFVIIa. At lower concentrations of rFVIIa (wild-type or variants), clot formation did occur but was significantly slower when TF activity was blocked. At increasing concentrations of rFVIIa, clotting times were no longer dependent on TF. In conclusion, should a TF-independent mechanism be involved in the efficacy of rFVIIa in patients with hemophilia, the superactive rFVIIa variants studied here might be clinically advantageous, as both procoagulant and antifibrinolytic potencies are significantly enhanced compared with those of wild-type rFVIIa. This ought to result in more efficient cessation of bleeding episodes and reduced risk of rebleeding.

Topics: Antifibrinolytic Agents; Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Tests; Blood Platelets; Carboxypeptidase B2; Coagulants; Dose-Response Relationship, Drug; Factor VII; Factor VIIa; Hemophilia A; Hemorrhage; Humans; In Vitro Techniques; Plasma; Recombinant Proteins; Thromboplastin

Topics: ADAM Proteins; ADAMTS13 Protein; Blood Coagulation Factor Inhibitors; Congresses as Topic; Creutzfeldt-Jakob Syndrome; Genetic Therapy; Hemorrhage; Hemostasis; Hepatitis C; Humans; Metalloendopeptidases; Protein C; Thromboplastin; Virus Diseases

We have discovered a novel canine hereditary bleeding disorder with the characteristic features of Scott syndrome, a rare defect of platelet procoagulant activity. Affected dogs were from a single, inbred colony and experienced clinical signs of epistaxis, hyphema, intramuscular hematoma, and prolonged bleeding with cutaneous bruising after surgery. The hemostatic abnormalities identified were restricted to tests of platelet procoagulant activity, whereas platelet count, platelet morphology under light microscopy, bleeding time, clot retraction, and platelet aggregation and secretion in response to thrombin, collagen, and adenosine diphosphate stimulation were all within normal limits. Washed platelets from the affected dogs demonstrated approximately twice normal clotting times in a platelet factor 3 availability assay and, in a prothrombinase assay, generated only background levels of thrombin in response to calcium ionophore, thrombin, or combined thrombin plus collagen stimulation. While platelet phospholipid content was normal, flow cytometric analyses revealed diminished phosphatidylserine exposure and a failure of microvesiculation in response to calcium ionophore, thrombin, and collagen stimulation. Pedigree studies indicate a likely homozygous recessive inheritance pattern of the defect. These findings confirm the importance of platelet procoagulant activity for in vivo hemostasis and provide a large animal model for studying agonist-induced signal transduction, calcium mobilization, and effector pathways involved in the late platelet response of transmembrane phospholipid movement and membrane vesiculation.

Topics: Animals; Blood Coagulation Factors; Blood Platelets; Dog Diseases; Dogs; Erythrocytes; Hemorrhage; Lipids; Phospholipids; Platelet Factor 3; Prothrombin; Thromboplastin

To study the effect of arsenic trioxide (As2O3) or all-trans retinoic acid (ATRA) on coagulopathy in patients with acute promyelocytic leukemia (APL), and the mechanism of hemorrhage in these patients.. Thrombomodulin (TM) or tissue factor (TF) transcription of mRNA of freshly isolated bone marrow blast from APL patients was detected by semi-quantitative RT-PCR. The parameters of coagulation and cell procoagulation activity (PCA) were assessed in plasmic levels. Bleeding symptom was observed during As2O3 or ATRA treatment.. TM expression in the APL cell surface was significantly upregulated from (14.31 +/- 1.60) ng/10(7) to (21.61 +/- 6.82) ng/10(7) cells. The levels of P-selectin, soluble fibrin monomer complex (SFMC) and D-dimer (D-D) decreased after ATRA or As2O3 treatment. Abnormal high expression of TF in APL cell was downregulated in patients treated with ATRA or As2O3. The expression level was (14.81 +/- 6.23) ng/L before treatment, but undetected after 20 days of treatment. In addition, the membrane PCA of fresh APL cells was predominantly FVII-dependent after ATRA or As2O3 treatment. Bleeding symptom was ameliorated during As2O3 or ATRA treatment.. Bleeding symptom was controlled in patients with APL after As2O3 or ATRA treatment.

Topics: Adult; Antineoplastic Agents; Arsenic Trioxide; Arsenicals; Blood Coagulation Disorders; Down-Regulation; Female; Hemorrhage; Humans; Leukemia, Promyelocytic, Acute; Male; Middle Aged; Oxides; RNA, Messenger; Thrombomodulin; Thromboplastin; Tretinoin

Active site-inhibited factor VIIa (FFR-rFVIIa) competes with factor VIIa (FVIIa) for binding to tissue factor (TF) and exerts an anti-thrombotic effect. We report an evaluation of the anti-thrombotic properties of FFR-rFVIIa in a model of thrombosis involving two thrombogenic surfaces. Uncoated glass capillaries or glass capillaries coated with TF were incorporated into an arterioarterial shunt in the rat and the occlusion time (OT) of the shunt was determined. An anti-thrombotic activity of FFR-rFVIIa was shown only on the TF-coated surface: the OT of the shunt was significantly prolonged, from 167 +/- 34 s in control animals to 312 +/- 42 s after i.v. bolus administration of 4 mg/kg FFR-rFVIIa. This OT was similar to those observed with the uncoated shunts in untreated animals (353 +/- 84 s). In vitro preincubation of the TF-coated shunt with FFR-rFVIIa significantly prolonged the OT to 245 +/- 45 s in the absence of detectable amounts of FFR-rFVIIa in the plasma. rFFR-rFVIIa weakly prolonged the tail template bleeding time by a factor of 1.5. This effect was more pronounced in animals pretreated with heparin. The anti-thrombotic and prohaemorrhagic effects of FFR-rFVIIa were totally reversed by administration of an equidose of rFVIIa. These results provide new information on the pharmacological properties of FFR-rFVIIa that will be useful for its clinical development.

Topics: Animals; Bleeding Time; Blood Platelets; Factor VIIa; Fibrin; Fibrinolytic Agents; Hemorrhage; Male; Models, Animal; Rats; Rats, Wistar; Recombinant Proteins; Thromboplastin; Thrombosis

To study the in vivo effect of all-trans-retinoic acid (ATRA) and arsenic trioxide (As(2)O(3)) on the expression of tissue factor (TF) and the other hemostatic disturbance, a series of parameters were measured either in bone marrow blasts or plasma from acute promyelocytic leukemia (APL) patients. The plasma parameters were measured by ELISA or chromogenic studies. The TF transcription was assessed using reverse transcription-polymerase chain reaction (RT-PCR) technique. The results indicated that the blast cell procoagulant activity (PCA), TF antigen of APL cell lysate, as well as the transcription of APL TF mRNA elevated at diagnosis, were reduced after ATRA or As(2)O(3) therapy. The plasma level of P-selectin, TF, thrombin-antithrombin complex (TAT), soluble fibrinmonomer complex, thrombomodulin (TM), tissue factor pathway inhibitor (TFPI), plasmin-antiplasmin complex, tissue plasminogen activator (t-PA) activity, urokinase plasminogen activator (u-PA) and its receptor (u-PAR), and D-dimer (D-D) significantly increased. Fibrinogen (Fg), antigen level of protein C (PC), plasminogen (PLG) activity, alpha(2)-plasminogen inhibitor activity (alpha(2)-PI), and plasminogen activator inhibitor (PAI) activity were decreased at diagnosis. The protein C activity (PC:A) and protein S (PS) remained unchanged. All the parameters were restored to normal ranges after complete remission (CR) except elevation of TF and TAT in both groups, as well as PC:A, PS, and t-PA in the ATRA group. In conclusion, there existed activation of platelets and consumption of anticoagulants as well as activation of coagulation and fibrinolytic system before treatment. Both ATRA and As(2)O(3) therapy downregulated the expression of TF mRNA, decreased the PCA and TF level in APL cells, significantly inhibited coagulation activation, corrected secondary hyperfibrinolysis and the other hemostatic abnormalities, and thus greatly improved the bleeding symptom in early stage of the treatment.

Topics: Adolescent; Adult; Arsenic Trioxide; Arsenicals; Case-Control Studies; Female; Hemorrhage; Hemostasis; Hemostatics; Humans; Leukemia, Promyelocytic, Acute; Male; Middle Aged; Oxides; Thromboplastin; Tretinoin

Studies were performed on a patient with a longstanding bleeding disorder whose major defects were impaired platelet prothrombinase activity in the absence of added factor Va, and a platelet factor V value that was either decreased or at the lower limit of normal when assayed on multiple occasions. In contrast, plasma factor V values were consistently normal. Unlike Scott Syndrome, in which platelet prothrombinase activity is decreased in both the presence and absence of added factor V, her platelets appeared to utilize added factor Va normally in supporting the generation of prothrombinase activity. These findings suggest an intrinsic defect in platelet factor V as the basis of her platelet prothrombinase defect. This defect appears to be different than that described in the Quebec platelet disorder (factor V Quebec). Immunoblot analyses of washed platelet lysates demonstrated a pattern of variably sized factor V molecules that was entirely similar to that observed in normal platelets, and both the heavy and light chains of her factor V after thrombin cleavage were of the same size as that observed in normal platelets. In addition, her platelet multimerin was normal and immunoblot analysis excluded the type of generalized granular protein defect and pathological proteolysis that has been suggested to explain the factor V defect in the Quebec platelet disorder. The findings in this patient thus suggest a new type of platelet factor V defect as the basis for the impaired capacity of her activated platelets to support prothrombinase generation. The findings further support an important role for platelet factor V in hemostasis.

Topics: Blood Coagulation Factors; Blood Platelet Disorders; Calcimycin; Dose-Response Relationship, Drug; Factor Va; Female; Hemorrhage; Humans; Kinetics; Thrombin; Thromboplastin

Hemorrhagic factor V inhibitors frequently bind to the second C-type (C2) domain of factor V and interfere with phospholipid binding. To define specific residues recognized by inhibitors from four patients (one bovine thrombin-induced and three spontaneous antibodies), epitope mapping was performed using recombinant human factor V lacking most of the B-type domain (FV des B) and alanine-substituted mutants within the C2 domain (FV des B C2 mutants). FV des B C2 mutants located in the region between Lys2060 and Glu2069 were resistant to inhibition by three IgG preparations including the bovine thrombin-induced antibody in both prothrombinase and phospholipid-binding assays. In contrast, mutations at Lys2087 and Lys2092/Glu2096 were significantly resistant to inhibition by the fourth IgG preparation in both prothrombinase and phospholipid-binding assays. These results confirm interference of phospholipid binding by hemorrhagic factor V inhibitors and support the role(s) of these residues in phospholipid binding.

Topics: Aged; Antibodies; Binding Sites; Blood Coagulation Tests; Epitope Mapping; Factor V; Hemorrhage; Humans; Male; Membranes, Artificial; Mutation; Phospholipids; Protein Binding; Protein Structure, Tertiary; Thromboplastin

The coagulation protease thrombin triggers fibrin formation, platelet activation, and other cellular responses at sites of tissue injury. We report a role for PAR1, a protease-activated G protein-coupled receptor for thrombin, in embryonic development. Approximately half of Par1-/- mouse embryos died at midgestation with bleeding from multiple sites. PAR1 is expressed in endothelial cells, and a PAR1 transgene driven by an endothelial-specific promoter prevented death of Par1-/- embryos. Our results suggest that the coagulation cascade and PAR1 modulate endothelial cell function in developing blood vessels and that thrombin's actions on endothelial cells-rather than on platelets, mesenchymal cells, or fibrinogen-contribute to vascular development and hemostasis in the mouse embryo.

Topics: Animals; Blood Coagulation; Blood Coagulation Factors; Blood Vessels; Calcium; Crosses, Genetic; Embryonic and Fetal Development; Endocardium; Endothelium, Vascular; Factor V; Female; Fibrinogen; Fibroblasts; Hemorrhage; Hemostasis; Male; Mice; Mice, Inbred C57BL; Mice, Inbred Strains; Mice, Transgenic; Neovascularization, Physiologic; Phenotype; Prothrombin; Receptor, PAR-1; Receptors, Thrombin; Signal Transduction; Thrombin; Thromboplastin

Hemophilia B is a sex-linked recessive bleeding disorder characterized by the presence of either a decreased amount of normal factor IX (FIX) or the presence of a dysfunctional FIX. We have identified a unique mutation in a family with mild hemophilia B. DNA analysis of family members revealed a single base transition in the 8th exon of the FIX gene predicting an amino acid change of Asn 346-->Asp in the catalytic domain. The FIX variant, named FIX Denver, was purified from proband plasma. Kinetic studies of factor X (FX) interactions with normal FIXa or FIXa Denver and phospholipid (PL) showed little difference in kcat but a significant difference when factor VIIIa (FVIIIa) was included in the reaction. Using kinetic assays to infer the Kd of FIXa for FVIIIa, normal FIXa had a Kd of 0.095 nM while that of FIXa Denver was 9.85 nM. The major defect caused by this point mutation is a marked decrease in the affinity of FIXa Denver for factor VIIIa.

Topics: Adult; Amino Acid Substitution; Blood Coagulation Tests; Cysteine Endopeptidases; DNA Mutational Analysis; Factor IX; Factor VIIIa; Factor X; Hemophilia B; Hemorrhage; Humans; Kinetics; Liposomes; Male; Mutation, Missense; Neoplasm Proteins; Phosphatidylcholines; Phosphatidylserines; Point Mutation; Thromboplastin

Liver cirrhosis is associated with alterations of the coagulation system commonly causing bleeding as well as thromboembolic complications. The potential pathophysiological roles of tissue factor (TF) (the initiator of the extrinsic coagulation pathway) and thrombomodulin (TM) (an initiator of the anticoagulatory protein C pathway) are unknown. We therefore measured plasma concentrations of TF and TM in 111 patients with liver diseases who were evaluated for liver transplantation. We could demonstrate that the levels of both molecules increased with the Child's class of liver cirrhosis, independently of aetiology. TM was significantly elevated in Child A, B and C patients compared with patients without cirrhosis; TF only in Child C patients. The plasma TM and TF concentrations correlated with prothrombin time, activated partial thromboplastin time, and inversely with factor VII activity, cholinesterase serum activity, and serum albumin concentration. TM was elevated in patients with a bleeding tendency, but TM and TF did not differ between patients with or without prior thrombotic events. Further studies are warranted to clarify the underlying mechanisms that raise TM and TF plasma levels in liver disease with possible clinical consequences.

Topics: Adolescent; Adult; Aged; Alanine Transaminase; Aspartate Aminotransferases; Female; Hemorrhage; Humans; Liver Cirrhosis; Male; Middle Aged; Partial Thromboplastin Time; Platelet Count; Prothrombin Time; Reference Values; Thromboembolism; Thrombomodulin; Thromboplastin

- Glycoprotein VI (GPVI) is a platelet-specific receptor for collagen that figures prominently in signal transduction. An addition to binding to type I and III collagens, GPVI is also bound specifically by collagen-related peptide and convulxin (CVX), a snake venom protein. We developed a quantitative assay of platelet GPVI in which biotin-conjugated CVX binds selectively to GPVI in separated total platelet proteins by a ligand blot procedure. Using this approach, we have documented a 5-fold range in platelet GPVI content among 23 normal healthy subjects. In addition, we have determined that CVX-induced or collagen-related peptide-induced prothrombinase activity is directly proportional to the platelet content of GPVI. A statistically significant correlation was observed at 2 CVX concentrations: 14.7 ng/mL (R(2)=0.854 and P<0.001, n=11) and 22 ng/mL (R(2)=0.776 and P<0.001, n=12). In previous studies, we established a similar range of expression of the integrin collagen receptor alpha(2)beta(1) on platelets of normal subjects. Among 15 donors, there is a direct correlation between platelet alpha(2)beta(1) density and GPVI content (R(2)=0.475 and P=0.004). In view of the well-documented association of GPVI with platelet procoagulant activity, this study suggests that the variation in GPVI content is a potential risk factor that may predispose individuals to hemorrhagic or thromboembolic disorders.

Topics: Blood Platelets; Crotalid Venoms; DNA, Complementary; Electrophoresis, Polyacrylamide Gel; Hemorrhage; Humans; Integrins; Lectins, C-Type; Platelet Activation; Platelet Membrane Glycoproteins; Receptors, Collagen; Thromboplastin; Thrombosis

Sulfated D-galactans occur on the red algae Botryocladia occidentalis as three fractions that differ in their sulfate content. Fractions F2 and F3 are potent anticoagulants. Like heparin, they enhance thrombin and factor Xa inhibition by antithrombin and/or heparin cofactor II. The inhibition potency increases simultaneously with the sulfate content of the fractions. The antithrombotic activity of these sulfated D-galactans was investigated on an experimental thrombosis model in which thrombus formation was induced by a combination of stasis and hypercoagulability. In contrast with heparin. the sulfated D-galactans showed a dual dose-response curve preventing thrombosis at doses up to approximately 0.5 mg/ kg body weight but losing the effect at higher doses. This unexpected behavior is probably due to a combined action of the sulfated D-galactan as anticoagulant and also as a strong inducer of platelet aggregation. In platelet-depleted animals the antithrombotic activity at higher dose of sulfated D-galactan is restored and almost total inhibition of thrombus formation is achieved. The sulfated D-galactan has no hemorrhagic effect even at high doses, possibly as a consequence of its effect on platelet aggregation. At comparable dose heparin has an intense bleeding effect. These results indicate that new polysaccharides, with well-defined structures, can help to distinguish events, such as antithrombotic and anticoagulant activities, bleeding and platelet-aggregating effects, which are obscure when induced simultaneously by a single compound.

Topics: Animals; Anticoagulants; Brazil; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Female; Fibrinolytic Agents; Galactans; Hemorrhage; Heparin; Male; Partial Thromboplastin Time; Phytotherapy; Plant Extracts; Platelet Aggregation; Rats; Rats, Wistar; Rhodophyta; Sulfates; Thromboplastin; Vena Cava, Inferior; Venous Thrombosis

Topics: Acute Disease; Animals; Antithrombin III; Blood Coagulation Disorders; Complement Activation; Cytokines; Disseminated Intravascular Coagulation; Endotoxemia; Fibrin; Gene Expression Regulation; Hemorrhage; Humans; Lipoproteins; Lung Injury; Primates; Protein C; Reactive Oxygen Species; Respiratory Distress Syndrome; Sepsis; Thromboplastin; Transcription, Genetic; Tumor Necrosis Factor-alpha

To clarify factors that may contribute to the development of intratumoral hemorrhage, we analyzed the expression of tissue factor (TF), an initiator of the extrinsic coagulation pathway, and of tissue factor pathway inhibitor (TFPI) in glioblastomas with or without massive intratumoral hematoma. Among 196 glioma cases reviewed, there were 13 with macroscopic intratumoral hemorrhage. We focused on the glioblastomas and used immunoblot- and immunohistochemical methods to compare the expression of TF and TFPI in 9 glioblastomas with macroscopic hematoma and 30 glioblastomas without macroscopic hemorrhage. Although TF was expressed in most glioblastomas irrespective of the presence or absence of macroscopic hemorrhage, the staining patterns differed significantly: TF-positive glioma cells were diffusely present in the non-hemorrhage group; in the group with hemorrhage, positive cells, primarily macrophages, were scattered throughout the tissue examined. The expression of TFPI was significantly higher in the group with than in the group without hemorrhage. Our results suggest that local suppression of the TF-dependent coagulation cascade is a contributing factor that permits the occurrence of intratumoral hemorrhage.

Topics: Adult; Aged; Brain Neoplasms; Child, Preschool; Female; Glioblastoma; Glioma; Hematoma; Hemorrhage; Humans; Immunoblotting; Immunohistochemistry; Lipoproteins; Macrophages; Magnetic Resonance Imaging; Male; Middle Aged; Thromboplastin; Tomography, X-Ray Computed

Factor VII (FVII) is a four-domain glycoprotein that plays a critical role in the initiation of blood coagulation. Hereditary deficiencies of this plasma protein results in a bleeding diathesis that varies in severity amongst affected patients. We have analysed the FVII gene in 27 patients with FVII deficiency from 21 unrelated families predominantly of Middle-Eastern extraction. A total of 19 different mutations were identified, of which 12 were novel and 7 had been previously reported. Nine of the 12 novel mutations were missense mutations located in the Gla domain (Ser23Pro), the second epidermal growth factor domain (Cys135Arg) and the catalytic serine protease domain (Arg247Cys, Arg277Cys, Ser282Arg, Pro303Thr, Ser363Ile, Trp364Cys, Trp364Phe), of which five are homozygous. Three novel splice mutations were identified in intron 1a (IVS1a+5), intron 2 (IVS2+1) and intron 6 (IVS6+1). Of the seven previously reported mutations, five were missense mutations of which three are homozygous (Gln100Arg, Arg152Gln, Arg304Gln, Cys310Phe and Thr359Met), one was a 17 bp deletion (10585del117bp) and one was a splice site mutation within intron 7 (IVS7+7). This study has significantly extended the current database of FVII mutations, including the number of known homozygous mutations. Conformational analyses of crystal structures for FVIIa and the FVIIa-tissue factor complex provided likely explanations for the effect of the missense mutations on FVIIa secretion or function. In particular, since 23 missense mutations were located to the serine protease domain, mostly to the region between the catalytic triad and the contact surface with tissue factor, this showed that the orientation of the serine protease domain relative to bound tissue factor in the complex is crucial for functional activity.

Topics: Adolescent; Adult; Amino Acid Sequence; Binding Sites; Child; Child, Preschool; DNA Mutational Analysis; Factor VII; Factor VII Deficiency; Family Health; Female; Hemorrhage; Hemostatics; Humans; Male; Middle Aged; Models, Molecular; Molecular Sequence Data; Mutation; Pedigree; Phenotype; Protein Structure, Tertiary; Serine Endopeptidases; Thromboplastin

Fibrin(ogen) is the major matrix ligand for beta3 integrins. If alpha(v)beta3 is the major receptor for fibrin(ogen) on intimal smooth muscle cells, we might expect to see this integrin associated with fibrin(ogen). Eighty-four specimens obtained from endarterectomies of 14 patients were studied. Fibrin was frequently observed in carotid intima even at the non-atherosclerotic areas. As for beta1 and beta3 integrins, beta1 was predominant in intima. The alpha(v)beta3 integrin expression was less frequent than alpha5beta1, another receptor for fibrin(ogen), in diffuse intimal thickening, fibrous cap and advanced plaques. Furthermore, alpha(v)beta3 was generally negative on smooth muscle cells in recent plaque ruptures. In conclusion, we suggest more attention should be paid on abundant fibrin matrix in intima. Histologically, the alpha5beta1 integrin rather than the alpha(v)beta3 is the major receptor for fibrin in intimal smooth muscle cells.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal; Antibody Specificity; Blotting, Western; Carotid Arteries; Carotid Artery Injuries; Carotid Stenosis; Endarterectomy, Carotid; Fibrin; Fibrinogen; Hemorrhage; Humans; Immunohistochemistry; Integrins; Ligands; Male; Middle Aged; Muscle, Smooth, Vascular; Receptors, Fibronectin; Receptors, Vitronectin; Thromboplastin; Tunica Intima

To obtain better insight into the pathogenesis of verotoxin-producing Escherichia coli-associated diseases, in this study, we explored the effect of verotoxin 2 (VT2) on coagulation in an animal model. After being given VT2 (50 ng/kg, lethal dose), C57BL/6 mice showed progressively increasing expression of TF mRNA in the kidney and brain and elevated plasma levels of thrombin-antithrombin III complex (TAT), normotest, fibrinogen, and PAI-1 paralleling the disease course over 24 hours; platelet counts were decreased at 48 hours with hemorrhage in the kidney and brain. Co-administration of lipopolysaccharide (LPS, 0.5 mg/kg) with VT2 (50 ng/kg) exhibited more prominant and/or prolonged increase in not only expression of TF and PAI-1 mRNAs in the kidney and brain but also plasma levels of TAT, fibrinogen, and PAI-1 and was associated with more remarkable hemorrhage in the tissues. Although VT2 (5 ng/kg) was not a lethal dose, co-administration of LPS (0.5 mg/kg) with VT2 (5 ng/kg) enhanced the susceptibility to VT2, resulting in more prolonged elevation of TAT levels during the first 24 hours than that in the LPS group and a second elevation at 72 hours, followed by death. Plasma IL-1beta level reached a maximum at 24 hours after VT2 (50 ng/kg) injection prior to the increase in TAT levels, whereas the increase in TNFalpha level immediately after injection was associated with the increase in PAI-1 mRNA. These observations indicate that the activation of coagulation by VT2 may occur through a mechanism different from that used by LPS, since plasma TAT levels rose in the mice immediately after LPS injection and returned to normal over 36 hours.

Topics: Animals; Antithrombin III; Blood Coagulation; Blood Coagulation Tests; Brain; Cytokines; Dose-Response Relationship, Drug; Drug Therapy, Combination; Fibrinogen; Hemorrhage; Intracranial Hemorrhages; Kidney; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Models, Animal; Neutrophils; Peptide Hydrolases; Plasminogen Activator Inhibitor 1; Platelet Count; RNA, Messenger; Shiga Toxin 2; Shock; Thromboplastin; Time Factors; Tissue Distribution

The anticoagulant and antithrombotic effects of YM-75466 (N-[4-[(1-acetimidoyl-4-piperidyl)oxy]phenyl]-N-[(7-amidino-2-naph thyl)methyl]sulfamoyl acetic acid monomethanesulfonate), a novel orally-active factor Xa (FXa) inhibitor, and warfarin were compared in mice. Both agents were orally administered in all studies. In ex vivo studies, the peak effects of YM-75466 occurred 1 hr after administration while the peak of warfarin activity occurred 18 hr after administration. At each peak, both YM-75466 and warfarin prolonged coagulation time dose-dependently. The dose response curve of warfarin for prothrombin time was steeper than that of YM-75466. In a thromboplastin-induced thromboembolism model, administration of 30 mg/kg YM-75466 or 3 mg/kg warfarin significantly improved the lethality ratio. In blood loss studies, YM-75466 did not increase blood loss from the tail even at 30 mg/kg, while warfarin markedly increased blood loss at 3 mg/kg. Agents that interfere with warfarin action did not interfere with YM-75466 action. In conclusion, this study shows that YM-75466 has advantages over warfarin: i) rapid onset of anticoagulant activity, ii) wide therapeutic range, iii) little effect on bleeding and iv) lack of drug interaction with agents that interfere with warfarin. These results suggest that YM-75466 may be promising as a novel oral anticoagulant agent.

Topics: Administration, Oral; Analgesics, Non-Narcotic; Animals; Anti-Bacterial Agents; Anticoagulants; Anticonvulsants; Antifibrinolytic Agents; Blood Coagulation; Carbamazepine; Cimetidine; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Erythromycin; Factor Xa Inhibitors; Fibrinolytic Agents; Hemorrhage; Male; Mice; Mice, Inbred ICR; Partial Thromboplastin Time; Phenytoin; Piperidines; Prothrombin Time; Rifampin; Sulfonamides; Thromboembolism; Thromboplastin; Vitamin K 1; Warfarin

Thrombogenic responses are sometimes seen after a large hemorrhage, but the precise mechanisms whereby this phenomenon occurs still remain unknown. We recently showed that plasminogen activator inhibitor-1 rises after a 20-ml/kg hemorrhage in rats and suggested that this change may be one of the contributing factors to the thrombogenic responses after a large hemorrhage. In this study, we set out to detect the changes on the coagulation side, that is, the changes in whole blood clotting time and the mRNA of tissue factor (TF), which is the primary initiator of the clotting cascade. The rats were all bled (20 ml/kg) 3 days after cannulation. The whole blood clotting time was measured by the Lee-White method. Changes in the TF mRNA were detected in the liver by high-performance liquid chromatography after reverse transcription and polymerase chain reaction using glyceraldehyde 3-phosphate dehydrogenase as an external standard. A 20-ml/kg hemorrhage significantly shortened the whole blood clotting time and significantly increased the TF mRNA in the liver at 1, 2, and 4h in comparison to the nonhemorrhage controls. These results indicate that a simple hemorrhage without tissue trauma can induce hypercoagulability and suggest that the induction of TF might be involved in this phenomenon.

Topics: Animals; Hemorrhage; Liver; Male; Plasminogen Activator Inhibitor 1; Polymerase Chain Reaction; Rats; Rats, Wistar; RNA, Messenger; Thromboplastin; Whole Blood Coagulation Time

Tissue factor (TF) and urokinase receptor (uPAR) are key cellular receptors triggering, respectively, coagulation and fibrinolysis. Bleeding complications among leukemic patients have been related to an abnormal expression of TF by blast cells and/or to an abnormal fibrinolytic response. In this study the expression of TF and uPAR has been assessed in 18 acute non-lymphoblastic and 8 lymphoblastic leukemic blast cells using several methodological approaches. TF mRNA was evaluated by in situ hybridization and TF and uPAR antigen were evaluated immunologically in cell lysates and on the cell surface by flow cytometry. In addition, TF-procoagulant activity was measured in coagulation-based assays. The reliability of these methods was corroborated in six leukemic cell lines of different lineages and states of maturation. Disseminated intravascular coagulation was detected in two M3 leukemia patients whose blast cells expressed high amounts of TF. Hyperfibrinolysis was detected in one M1 and two M2 patients, whose blast cells displayed a high content of uPAR antigen, but no TF. Furthermore, M5 leukemia blast cells expressed both TF and uPAR, although no hemostatic defects or bleeding complications were detected in these patients. Taken together, although a limited number of patients was included in this study, these data suggest that in leukemia patients exhibiting bleeding, either TF or uPAR are expressed by their blast cells. However, the presence of these receptors does not necessarily imply the existence of a hemostatic disorder.

Topics: Acute Disease; Blood Coagulation; Hemorrhage; Humans; Leukemia; Receptors, Cell Surface; Receptors, Urokinase Plasminogen Activator; Thromboplastin; Tumor Cells, Cultured

Blood coagulation in vivo is initiated by factor VII (FVII) binding to its cellular receptor tissue factor (TF). FVII is the only known ligand for TF, so it was expected that FVII-deficient embryos would have a similar phenotype to TF-deficient embryos, which have defective vitello-embryonic circulation and die around 9.5 days of gestation. Surprisingly, we find that FVII-deficient (FVII-/-) embryos developed normally. FVII-/- mice succumbed perinatally because of fatal haemorrhaging from normal blood vessels. At embryonic day 9.5, maternal-fetal transfer of FVII was undetectable and survival of embryos did not depend on TF-FVII-initiated fibrin formation. Thus, the TF-/- embryonic lethal and the FVII-/- survival-phenotypes suggest a role for TF during embryogenesis beyond fibrin formation.

Topics: Animals; Blood Coagulation; Culture Techniques; Embryonic and Fetal Development; Factor VII; Female; Fetal Death; Fibrin; Gene Targeting; Hemorrhage; Hemostasis; Maternal-Fetal Exchange; Mice; Mice, Inbred C57BL; Mutagenesis; Pregnancy; Thromboplastin

Tissue factor (TF) is the cellular receptor for coagulation factor VI/VIIa and is the membrane-bound glycoprotein that is generally viewed as the primary physiological initiator of blood coagulation. To define in greater detail the physiological role of TF in development and hemostasis, the TF gene was disrupted in mice. Mice heterozygous for the inactivated TF allele expressed approximately half the TF activity of wild-type mice but were phenotypically normal. However, homozygous TF-/- pups were never born in crosses between heterozygous mice. Analysis of mid-gestation embryos showed that TF-/- embryos die in utero between days 8.5 and 10.5. TF-/- embryos were morphologically distinct from their TF+/+ and TF+/- littermates after day 9.5 in that they were pale, edematous, and growth retarded. Histological studies showed that early organogenesis was normal. The initial failure in TF-/- embryos appeared to be hemorrhaging, leading to the leakage of embryonic red cells from both extraembryonic and embryonic vessels. These studies indicate that TF plays an indispensable role in establishing and/or maintaining vascular integrity in the developing embryo at a time when embryonic and extraembryonic vasculatures are fusing and blood circulation begins.

Topics: Animals; Base Sequence; Blood Coagulation Disorders; DNA Primers; Fetal Death; Genes, Lethal; Hemorrhage; Heterozygote; Homozygote; Mice; Molecular Sequence Data; Phenotype; Thromboplastin

SANORG 32701 is a new sulfated pentasaccharide obtained by total chemical synthesis. It is analogue of the "synthetic pentasaccharide" (SR 90107/ORG 31540), which represents the antithrombin III (AT-III) binding site of heparin. Like SR 90107, it shows high affinity for human AT-III (Kd = 3.7 +/- 0.7 nmol/L) and is a potent catalyst of its inhibitory effect with regard to factor Xa (1100 +/- 31 versus 850 +/- 27 anti-Xa U/mg for SR 90107). SANORG 32701 inhibited thrombin generation occurring via both the extrinsic and intrinsic pathways in vitro. After intravenous or subcutaneous administration to rabbits or rats, SANORG 32701 displayed prolonged anti-factor Xa activity and inhibition of thrombin generation ex vivo. SANORG 32701 was slowly eliminated, showing elimination half-lives between 2.8 and 4.9 hours with different doses. SANORG 32701 displayed antithrombotic activity by virtue of its potentiation of the anti-factor Xa activity of AT-III. It strongly inhibited thrombus formation in an experimental model of thromboplastin-induced venous thrombosis in rats (intravenously) and rabbits (subcutaneously) (ED50 values were 25.5 +/- 4.1 and 91 +/- 12.7 nmol/kg, respectively). SANORG 32701 inhibited the accretion of fibrinogen I 125 to a preformed thrombus in the rabbit jugular vein and significantly reduced thrombus growth occurring after electrical stimulation of the rabbit carotid artery. In the rabbit, intravenous injection of SANORG 32701 enhanced tissue plasminogen activator (TPA)-induced thrombolysis, suggesting that concomitant use of SANORG 32701 during TPA therapy may be helpful in preventing thrombus accretion, thus facilitating clot lysis. In the rat, SANORG 32701 potently inhibited thrombus formation induced on a silk thread in an arteriovenous shunt and in the vena cava. Compared with standard heparin, SANORG 32701 (1000 nmol/kg IV) caused only minimal bleeding enhancement and exhibited a favorable antithrombotic activity/ bleeding risk ratio, therefore showing that it might be considered as a promising compound in the treatment and prevention of various thrombotic diseases.

Topics: Animals; Anticoagulants; Electric Stimulation; Factor Xa Inhibitors; Fibrinogen; Fibrinolytic Agents; Hemorrhage; Heparin; Humans; Ligation; Male; Oligosaccharides; Rabbits; Rats; Rats, Wistar; Thrombin; Thromboplastin; Thrombosis; Tissue Plasminogen Activator; Venae Cavae

Coagulation factor V is a critical cofactor for the activation of prothrombin to thrombin, the penultimate step in the generation of a fibrin blood clot. Genetic deficiency of factor V results in a congenital bleeding disorder (parahaemophilia), whereas inheritance of a mutation rendering factor V resistant to inactivation is an important risk factor for thrombosis. We report here that approximately half of homozygous embryos deficient in factor V (Fv-/-), which have been generated by gene targeting, die at embryonic day (E) 9-10, possibly as a result of an abnormality in the yolk-sac vasculature. The remaining Fv-/- mice progress normally to term, but die from massive haemorrhage within 2 hours of birth. Considered together with the milder phenotypes generally associated with deficiencies of other clotting factors, our findings demonstrate the primary role of the common coagulation pathway and the absolute requirement for functional factor V for prothrombinase activity. They also provide direct evidence for the existence of other critical haemostatic functions for thrombin in addition to fibrin clot formation, and identify a previously unrecognized role for the coagulation system in early mammalian development.

Topics: Animals; Crosses, Genetic; Embryonic and Fetal Development; Factor V; Factor V Deficiency; Female; Fetal Death; Gene Targeting; Hemorrhage; Homozygote; Male; Mice; Mice, Inbred C57BL; Thromboplastin

The neutralization by protamine sulfate of bleeding enhancement induced by the potent anti-factor Xa pentasaccharide SR 90107A/Org 31540 and by heparin has been studied in rats and mice. Bleeding, as measured by transection of the tail of anaesthetised rats or mice, was increased following the administration of heparin and very high doses of SR 90107A/Org 31540. In rats, i.v. doses of 0.6 mg/kg heparin or 15 mg/kg SR 90107A/Org 31540 were required to enhance bleeding time to approximately the same extent (5- or 7-fold increase), whereas in mice a 13-fold increase in blood loss was observed with i.v. doses of 3 mg/kg heparin or 10 mg/kg SR 90107A/Org 31540. Protamine sulfate (10 mg/kg i.v.) reduced bleeding in rats and mice induced by both compounds. It also neutralized the anti-factor Xa activity as well as the antithrombotic activity of heparin as observed in venous thrombosis models in both species. However, protamine sulfate neither affected the anti-factor Xa activity nor the antithrombotic activity of SR 90107A/Org 31540 in rats and mice. The present results suggest that protamine sulfate may be regarded as a potential antidote to neutralize bleeding side-effects in cases of SR 90107A/Org 31540 overdosing.

Topics: Animals; Bleeding Time; Factor Xa Inhibitors; Fibrinolytic Agents; Hemorrhage; Heparin; Heparin Antagonists; Humans; Male; Mice; Oligosaccharides; Protamines; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Species Specificity; Thromboembolism; Thromboplastin

A patient undergoing intracranial surgery developed disseminated intravascular coagulation with life threatening peroperative bleeding. Thromboelastography established the diagnosis of hyperfibrinolysis, usually a fatal complication of a neurosurgical operation. With the administration of a high dose regimen of aprotinin (Trasylol) the haemorrhage was controlled and the hyperfibrinolytic state reversed. Evaluation of blood samples from the jugular bulb suggested that there was a pronounced local release of tissue plasminogen activator into the circulation.

Topics: Aged; Aprotinin; Brain; Brain Neoplasms; Craniotomy; Dose-Response Relationship, Drug; Fatal Outcome; Fibrinolysis; Glioblastoma; Hemorrhage; Humans; Injections, Intravenous; Male; Postoperative Complications; Prothrombin; Thrombelastography; Thromboplastin

Antioxidants occasionally have become prooxidants when a large amount was ingested. The haemorrhagic toxicity of butylated hydroxytoluene, a synthetic antioxidant, may involve such a mechanism. This study investigated whether haemorrhage is induced by overdoses of tocopherols, beta-carotene, ubiquinone or L-ascorbic acid, which are representative biological antioxidants. Male Jcl:SD rats (six rats/group) were fed d-alpha, d-beta, d-gamma or d-delta-tocopherols, ubiquinone Q-10, beta-carotene or retinol acetate at a level of 0.5%, or L-ascorbic acid at 5% in the diet for 7 days. Only two rats given retinol acetate died with lung haemorrhages. Haemorrhages were observed in five or six, six, one, one, one or one of six surviving rats given d-alpha, d-beta or d-gamma-tocopherols, ubiquinone Q-10, beta-carotene or retinol acetate, respectively (except for a retinol group in which four rats survived). Major haemorrhages were noted in the epididymis. In the alpha-, beta- and gamma-tocopherol, ubiquinone Q-10, beta-carotene or retinol acetate-treated groups, prothrombin and kaoline-activated partial thromboplastin time indices were 26-28, 37, 59, 42, 63 and 65% or 27-28, 35, 65, 38, 59 and 28%, respectively, of the control values. Only the prothrombin index was significantly decreased to 67% in delta-tocopherol-administered rates, whereas controls and those receiving L-ascorbic acid showed no signs of bleeding or coagulation defect. The same tendency was also seen in the decreasing effect on vitamin K-dependent blood coagulation factors. These results suggest that the four naturally occurring tocopherols have a tendency to cause haemorrhage in the order of alpha > beta > gamma > delta, and ubiquinone Q-10 and beta-carotene als0o have relatively strong and weak haemorrhagic effects, respectively, with regard to prothrombin and partial thromboplastin time indices.

Topics: Adjuvants, Immunologic; Analysis of Variance; Animals; Anticarcinogenic Agents; Antineoplastic Agents; Ascorbic Acid; beta Carotene; Blood Coagulation; Carotenoids; Diterpenes; Epididymis; Exophthalmos; Eye; Hemorrhage; Male; Prothrombin Time; Rats; Rats, Sprague-Dawley; Retinyl Esters; Stereoisomerism; Thromboplastin; Ubiquinone; Vitamin A; Vitamin E

To assess the organization and the quality of care of an anticoagulation clinic, the structure, the process of laboratory control and the clinical outcome in our Center are described. 1068 patients under control in 1994 (M/F 572/496; median age 63 range 6-91 ys., 74% in long-term prophylaxis) were evaluated. The clinic was run twice weekly by a physician, two nurses and a technician; management for emergencies was always warranted. Prothrombin time was carried out with a sensitive thromboplastin (ISI < 1.1) and a computer program provided calculation and graphical representation of INR, comparison with therapeutic range, automatic dosage prescription and print out. Laboratory quality of therapy was assessed by three different techniques: 'cumulative INR', 'last check in file' and 'linear change', yielding respectively 69% of laboratory controls, 71% of patients and 80% of days within the therapeutic range. The rate of thrombosis, major and total bleeding were respectively 0.2%, 0.2% and 12.5%. An anticoagulation clinic represents an effective organizational model for the management of patients taking oral anticoagulants.

Topics: Administration, Oral; Anticoagulants; Blood Coagulation Tests; Drug Utilization; Forecasting; Forms and Records Control; Hemorrhage; Humans; Incidence; Italy; Medical Records Systems, Computerized; Outcome and Process Assessment, Health Care; Outpatient Clinics, Hospital; Patient Care Planning; Patient Care Team; Reference Standards; Thromboplastin; Thrombosis

The introduction of the INR system for the monitoring of oral anticoagulant control represents a major advance, not only in terms of therapeutic efficacy but also in respect of patient safety. It is important to recognize that the system is only viable if careful attention is paid to the many important variables which contribute to its overall value. These include the choice of thromboplastin, assignation of ISI, determination of the mean normal prothrombin time and the method of end-point detection. Participation in independent external quality assessment schemes permits a unique opportunity for individual laboratories to identify, through laboratory performance analysis, problems relating to their own laboratory practice. Another major advantage, particularly of the larger schemes, is the identification of poor reagents and coagulometers and inconsistencies in their performance. One example of this is the recent identification of problems in respect of ISI assignment for thromboplastins used with coagulometers. This, in turn, provided the necessary stimulus to the potentially important development of calibrants for local ISI determination (21).

Topics: Administration, Oral; Aged; Animals; Anticoagulants; Blood Coagulation Tests; Calibration; Cattle; Hemorrhage; Humans; Medical Audit; Middle Aged; Prothrombin Time; Quality Assurance, Health Care; Quality Control; Rabbits; Recombinant Proteins; Reference Standards; Safety; Sensitivity and Specificity; Thromboplastin; Warfarin

The synthesis of tissue factor pathway inhibitor (TFPI) was investigated in cloned human synovial cells and human chondrocytes. TFPI-specific DNA transcription products of these cells were isolated, and a full-length cDNA of about 1000 base pairs was amplified by reverse transcription and polymerase chain reaction. The amplified DNA was cloned into the vector pUC 18. The TFPI coding sequence was confirmed by double stranded sequencing and was identical with that previously published for human TFPI coding nucleotide sequence from human placental cDNA (1). The inhibitory activity of TFPI in the cell medium of cultivated human chondrocytes and cloned human synovial cells was determined by a specific chromogenic substrate assay of factor Xa activity. The inhibitory activity of TFPI in the medium of human chondrocytes and cloned human synovial cells was 630-720 mU/10(8) cells and 1080-1665 mU/10(8) cells, respectively. In addition, TFPI activity in cell culture media of human chondrocytes and cloned human synovial cell was suppressed by a polyclonal goat anti-TFPI antibody directed against the inhibitory domain I and domain II. In the chromogenic substrate assay, the anti-TFPI antibody completely suppressed the inhibitory activity of TFPI in the samples.

Topics: Amino Acid Sequence; Antibodies; Antibody Specificity; Base Sequence; Cartilage; Cells, Cultured; DNA, Complementary; Factor VII; Hemophilia A; Hemorrhage; Humans; Lipoproteins; Molecular Sequence Data; RNA; Synovial Membrane; Thromboplastin; Transcription, Genetic

The seminal vesicle protein No. 4 (SV-IV) secreted from the rat seminal vesicle epithelium, possesses immunosuppressive and anti-inflammatory properties and it is a potent inhibitor of platelet aggregation both in vivo and in vitro. This research aimed to investigate the possible effect of SV-IV on the process of human blood coagulation. Preliminary experiments showed that the recalcification time (RT) of platelet-poor plasma (PPP) samples, obtained from both normal subjects and patients affected by some hemorrhagic disorders, was found to be markedly reduced in the presence of micromolar amounts of SV-IV. It was demonstrated that the concentration of free antithrombin III (AT III) occurring in blood sera obtained from PPP samples recalcified in the presence of SV-IV was significantly decreased in comparison with sera obtained from PPP recalcified in the absence of SV-IV. It was also shown that PPP treatment with SV-IV significantly reduced the concentration of free AT III without affecting the levels of other plasma serine protease inhibitors, such as alpha 2-macroglobulin, alpha 1-antitrypsin and C1-inhibitor. In addition, the RT of PPP treated with a specific rabbit anti-AT III polyclonal antiserum (anti-AT III treated PPP) was not modified by SV-IV. These findings were confirmed by the observation that the addition of SV-IV into an in vitro coagulation system, containing pure fibrinogen, alpha-thrombin and AT-III, resulted in complex suppression of thrombin inhibition by AT III. No other steps of the blood clotting process (prothrombinase complex, factor XIII, fibrinogen concentration) were affected by SV-IV.

Topics: Animals; Antithrombin III; Blood Coagulation; Calcium Chloride; Dose-Response Relationship, Drug; Factor XIII; Fibrinogen; Hemorrhage; Humans; In Vitro Techniques; Prostatic Secretory Proteins; Proteins; Rats; Seminal Plasma Proteins; Serpins; Thromboplastin

A seventeen-year-old man with hemophilia A developed nausea, vomiting, and unsteady gait after mild head trauma. Magnetic resonance imaging clearly demonstrated localized bleeding in cerebellar vermis. Quick administration of factor VIII concentrates prevented further extension of the bleeding and the patient completely recovered without neurologic impairment. In hemophiliac patients, careful evaluation of intracranial lesions is desired after head trauma even if they show only nonspecific symptoms.

Topics: Adolescent; Cerebellar Diseases; Craniocerebral Trauma; Hemophilia A; Hemorrhage; Humans; Magnetic Resonance Imaging; Male; Thromboplastin; Tomography, X-Ray Computed

A method is described by which the time-course of thrombin generation in plasma can be obtained from a continuous optical density recording of p-nitroaniline (pNA) production in a 2:3 diluted plasma. A chromogenic substrate, methylmalonyl-methylanalyl-arginyl-pNA (SQ 68), is used that is specifically split by thrombin but at a low rate. The thrombin that appears and disappears in the plasma does not split more than 5% of the substrate added, so the rate of substrate conversion is in good approximation proportional to the amidolytic activity in the plasma over the entire period of thrombin generation. The course of the enzyme concentration can be calculated from the amidolytic activity curve. It is shown that the thrombin generation curves obtained in this way are essentially identical to those obtained via the classical subsampling method. The presence of SQ 68 influences the amount of free thrombin that appears in plasma because it competitively inhibits the inactivation of thrombin by AT III and alpha 2 macroglobulin. The inhibition of the thrombin peak by heparin, relative to an uninhibited control, remains unaltered by the presence of the substrate. From the course of thrombin activity and the prevailing decay constants, the course of prothrombin conversion velocity can be calculated. Prothrombin conversion was seen to be inhibited at high (> 500 microM) substrate concentrations only, and experimental conditions are found under which the inhibition of the clotting process by the substrate is negligible. The amidolytic activity is the sum of the activities of free thrombin and of the alpha 2 macroglobulin-thrombin complex formed.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: alpha-Macroglobulins; Chromogenic Compounds; Dipeptides; Hemorrhage; Humans; Kinetics; Malonates; Spectrophotometry; Thrombin; Thromboplastin

Patients receiving long-term anticoagulant therapy may be subject to unnecessary risks of bleeding or thromboembolism because of variability in the commercial thromboplastins used to determine prothrombin time and consequent uncertainty about the actual intensity of anticoagulation.. We explored the effect of this uncertainty on the benefits and risks of anticoagulation in patients with prosthetic heart valves, using models of thromboembolic and hemorrhagic complications as a function of the intensity of anticoagulation, with quality-adjusted life expectancy and average variable costs used to describe outcomes.. Anticoagulation provides a striking benefit for patients whose treatment is conducted within the recommended range of the international normalized ratio (INR)--i.e., 2.5 to 3.5--but if uncertainty about the laboratory results causes the intensity of anticoagulation to fall outside this range, the gain becomes smaller. Uncertainty about the true intensity of anticoagulation may reduce the potential gain in life expectancy, adjusted for quality of life, by more than half and may increase the ratio of costs to effectiveness to almost five times the optimal value. Variability in the intensity of anticoagulation is even greater if older recommendations advocating a higher level of anticoagulation are followed.. Uncertainty about the sensitivities of the commercially available thromboplastins used in the United States can have important clinical and economic effects. This problem could be eliminated if clinical laboratories uniformly reported the intensity of anticoagulation as the INR, by adjusting prothrombin-time ratios for variability in thromboplastins.

Topics: Cost-Benefit Analysis; Decision Support Techniques; Drug Monitoring; Heart Valve Prosthesis; Hemorrhage; Humans; Markov Chains; Prothrombin Time; Quality of Life; Reference Values; Risk Factors; Sensitivity and Specificity; Thromboembolism; Thrombolytic Therapy; Thromboplastin

Previous studies on recombinant human soluble thrombomodulin (rsTM) from Chinese hamster ovary cells revealed that rsTM was expressed as two proteins that differed functionally in vitro due to the presence (rsTM beta) or absence (rsTM alpha) of chondroitin-4-sulfate. The current study evaluates the in vivo behavior of rsTM in rats and in a rat model of tissue factor-induced disseminated intravascular coagulation (DIC). rsTM beta was more potent than rsTM alpha for prolongation of the activated partial thromboplastin time (APTT) and their in vivo half-lives determined by ELISA were 20 min for rsTM beta and 5.0 h for rsTM alpha. Injection of a tissue factor suspension (5 mg/kg) resulted in DIC as judged by decreased platelet counts and fibrinogen concentrations, prolonged APTT, and increased fibrin and fibrinogen degradation products (FDP) levels. A bolus injection of either rsTM (0.2 mg/kg) 1 min before induction of DIC essentially neutralized effects on platelets, fibrinogen, and FDP levels, and had only a moderate effect on APTT prolongation. The dose of anticoagulant to inhibit the drop in platelet counts by 50% (ED50) was 0.2 mg/kg rsTM alpha, 0.07 mg/kg rsTM beta, and 7 U/kg heparin. The effect of increasing concentrations of rsTM and heparin on bleeding times were compared in experiments involving incision of the rat tail. Doubling of the bleeding times occurred at 5 mg/kg rsTM alpha, 3 mg/kg rsTM beta or 90 U/kg heparin. These values represent a 25-fold increase over the ED50 for rsTM alpha, 43-fold for rsTM beta and 13-fold for heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Disease Models, Animal; Disseminated Intravascular Coagulation; Enzyme-Linked Immunosorbent Assay; Fibrinogen; Fibrinolysis; Glycosaminoglycans; Hemorrhage; Heparin; Male; Platelet Count; Rats; Rats, Inbred Strains; Receptors, Cell Surface; Receptors, Thrombin; Recombinant Proteins; Solubility; Thromboplastin

Recombinant human factor VIIa (rFVIIa) was given to warfarin-treated rats. One and two warfarin treatments reduced endogenous factor X levels to about 10% and less than 5%, respectively. The reduction of plasma levels of vitamin K-dependent coagulation factors was accompanied by a treatment-dependent prolongation of activated partial thromboplastin time (APTT) and prothrombin time (PT) as well as by increased bleeding time and blood loss in the rat tail bleeding test. rFVIIa 50 micrograms/kg and 250 micrograms/kg normalized PT and shortened APTT in rats given warfarin once. Bleeding was completely normalized by rFVIIa 250 micrograms/kg. In rats given warfarin twice rFVIIa 250 micrograms/kg shortened PT but had no effect on APTT, whereas the effect on bleeding was variable. The elimination half life of rFVIIa in rats was found to be 30-40 minutes. The study indicates that rFVIIa may be useful in patients with bleeding due to decreased levels of vitamin K-dependent coagulation factors.

Topics: Animals; Factor VIIa; Factor X; Female; Hemorrhage; Humans; Male; Partial Thromboplastin Time; Prothrombin; Prothrombin Time; Rats; Rats, Inbred Strains; Recombinant Proteins; Thromboplastin; Warfarin

When male Sprague-Dawley rats were administered d-alpha-tocopherol and butylated hydroxytoluene in the diet or intraperitoneally for 7 days, prolongations of prothrombin time and partial thromboplastin time were observed in those given both chemicals by both routes in a dose-dependent manner. However, intraperitoneal d-alpha-tocopherol was less toxic and the prothrombin and partial thromboplastin time indices were approx. 70% and approx. 60% in rats given 2.91 mmol/kg body weight daily. Rats given d-alpha-tocopherol in the diet at a daily dose of 2.31 mmol/kg body weight were approx. 13% and approx. 16% of the control, and in those dietary groups severe hemorrhages in epididymis and other organs were also observed. Plasma concentrations of total tocopherols were more increased by the dietary than the intraperitoneal route. These results suggest that the great difference in the hemorrhagic effect of d-alpha-tocopherol between dietary and intraperitoneal route administration may largely be due to the differing absorption rates of the drug by these two means.

Topics: Administration, Oral; Animals; Butylated Hydroxytoluene; Diet; Hemorrhage; Injections, Intraperitoneal; Intestinal Absorption; Male; Prothrombin Time; Rats; Rats, Inbred Strains; Thromboplastin; Vitamin E

Fibrinolytic and fibrinase properties of the most of human organs and tissues have been studied. It has been established that fibrinolytic activity of the tissues highly varied. Fibrinolytic agents of the tissues are rather unstable to dilution, in contrast to thromboplastin, that is stable to dilutions as 1:10000 and 1:100000 and higher. All the tissues contain both activators and inhibitors of fibrinolysis. In some of them inhibitors prevail, that proves their antifibrinolytic properties. Tissue fibrinase decreasing fibrinolysis effectiveness, is detected almost in all tissues. The experiments with intravenous injection of extracts from different tissues have demonstrated that regardless of their fibrinolytic activity, the course of hemostasis impairment is of the same type: at the moment of the extract injection fibrinolysis is sharply inhibited, and then intravasal blood coagulation develops under the influence of strong tissue thromboplastin; the phase of hypercoagulemia is changed by that of hypocoagulemia attended by a secondary increase of fibrinolysis. The author believes that when "juices" of different tissues enter the blood flow the impairment of blood coagulation, by the mechanism of thrombohemorrhage syndrome (THS) takes place, and fibrinolysis is secondary-activated and represents a reaction of the second phase of THS.

Topics: Coagulants; Fibrin; Fibrinolysis; Fibrinolytic Agents; Hemorrhage; Humans; In Vitro Techniques; Thromboplastin; Thrombosis; Tissue Extracts

Topics: Administration, Intravesical; Aged; Drug Therapy, Combination; Ergonovine; Hemorrhage; Humans; Male; Prostatectomy; Thromboplastin

We have evaluated the performance of a centrifugal analyzer, specifically designed for hemostasis tests, for methods based on clotting time as measured by light scattering, or based on splitting of chromogenic substrates. The results were compared with those obtained with a semiautomated coagulometer (clotting tests) or with a manually operated photometer (chromogenic tests). In general, the results with the centrifugal analyzer were at least as precise as those of the comparative methods, with greater output and ease of operation. Disadvantages of the instrument are its partial incompatibility with some commercial reagents and the relative rigidity of the operational parameters, which hinder its use for research.

Topics: Antithrombin III; Autoanalysis; Centrifugation; Fibrinogen; Hemorrhage; Hemostasis; Humans; Light; Plasminogen; Scattering, Radiation; Thromboplastin; Thrombosis

Topics: Anticoagulants; Blood Coagulation; Dose-Response Relationship, Drug; Hemorrhage; Humans; Partial Thromboplastin Time; Thromboplastin; Thrombosis

Topics: Administration, Oral; Anticoagulants; Hemorrhage; Humans; Prothrombin Time; Thrombophlebitis; Thromboplastin

Topics: Animals; Anticoagulants; Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Factors; Cysteine Endopeptidases; Disseminated Intravascular Coagulation; Endopeptidases; Factor X; Factor Xa; Female; Fibrin Fibrinogen Degradation Products; Fibrinolysis; Hemorrhage; Humans; Male; Neoplasm Metastasis; Neoplasm Proteins; Neoplasms; Neoplasms, Experimental; Thromboembolism; Thromboplastin

The prothrombin time, activated partial thromboplastin time, thrombin time, and skin bleeding time, with assays of factors II, VII, IX, and X, platelet count, and liver function tests were performed on a group of patients receiving long term warfarin therapy. There were 17 bleeding patients and 13 non-bleeding patients. A study was made, using the Australasian Reference Thromboplastin and 2 other thromboplastic reagents in common use. The Australasian Reference Thromboplastin was shown to be more sensitive to the coumarin induced coagulation defect than rabbit brain thromboplastin, and hence of more value in preventing haemorrhagic complications. The level of factor II assayed by the one stage method was a useful independent indicator of the intensity of oral anticoagulation, and correlated well with the development of bleeding.

Topics: Bleeding Time; Hemorrhage; Humans; Indicators and Reagents; Partial Thromboplastin Time; Prothrombin; Prothrombin Time; Thrombin Time; Thromboplastin; Warfarin

A comparative study was made of 2 thromboplastins, the Australasian Reference Thromboplastin, and Simplastin, in a large group of patients on long-term Warfarin therapy. 373 individual samples were obtained. Calibration constants were obtained for those patients with prothrombin ratios within the therapeutic range, and for those well outside the therapeutic range, and found to be different. Study of the relationship between the 2 thromboplastins indicates that comparability is linear only within a specified limited range of prothrombin ratios. At the two extreme ends the relationship is curved, suggesting a logarithmic relationship. Attention is drawn to the need of caution in interpretation of corrected ratios calculated on a linear relationship especially when the ratio is above 4.0 as this may have clinical implications.

Topics: Coumarins; Hemorrhage; Humans; Mathematics; Prothrombin Time; Thromboplastin; Warfarin

Topics: Animals; Butylated Hydroxytoluene; Cerebral Hemorrhage; Cricetinae; Dogs; Guinea Pigs; Hemorrhage; Liver; Mice; Phenols; Prothrombin Time; Quail; Rabbits; Rats; Thromboplastin

To evaluate the use of the activated partial thromboplastin time (APTT), as measured by the Coag-A-Mate semi-automatic unit, in lowering the dosage of heparin in stable chronic hemodialysis patients, four protocols for anticoagulation were utilized. Ten patients were dialyzed five times with each protocol. In protocol I, clotting time was performed baseline, 2 and 4 hours and in protocol II, baseline and every 30 minutes, with heparin administered by bolus to keep the clotting time at 2-2 1/2 times normal. In protocols III and IV the APTT was performed every 30 minutes, with heparin given by bolus in protocol III and infusion in protocol IV, to keep the APTT 1 1/2-2 times normal. Protocol I required 6000 +/- 543 U of heparin with the dose decreasing significantly to 3694 +/- 158 U in protocol II, 2634 +/- 139 U in protocol III and 2013 +/- 117 U in protocol IV (P less than 0.05- less than 0.001). Three episodes of clotting occurred, one in protocol III and two in protocol IV. There was no bleeding, and clearances of urea, creatinine, phosphate and uric acid at 1 and 5 hours were similar in all protocols. APTT, as measured by the Coag-A-Mate unit, provides a simple means of lowering heparin requirements in routine dialysis patients.

Topics: Blood Coagulation; Blood Coagulation Tests; Evaluation Studies as Topic; Hemorrhage; Heparin; Humans; Protamines; Renal Dialysis; Thromboplastin; Time Factors

Activated coagulation time (ACT) for protamine reversal was monitored in 28 consecutive patients (Group 1) and a standard heparin-protamine protocol was used for an earlier series of 28 patients (Group 2). Although Group 1 received a significantly higher total heparin dose than Group 2 (p less than 0.01), the protamine dose for reversal was significantly less for the ACT group than for the controls (p less than 0.0005). The mean ratio of protamine to total heparin was 1 : 1 (range, 0.33 to 1.44) for the ACT group and 2 : 1 (range, 1.42 to 2.59) for the controls. There were no significant differences between the two groups in operative and postoperative blood loss, transfusion requirements, hematocrit, and partial thromboplastin time. This study shows that the ACT test did not reduce postoperative bleeding significantly when compared with our standard protocol. It also indicates that there is wide individual sensitivity to heparin and that significantly less protamine is required for reversal.

Topics: Blood Coagulation Tests; Blood Transfusion; Cardiac Surgical Procedures; Cardiopulmonary Bypass; Evaluation Studies as Topic; Hematocrit; Hemorrhage; Heparin; Humans; Middle Aged; Monitoring, Physiologic; Postoperative Complications; Protamines; Thromboembolism; Thromboplastin

Successful prevention of the progression of incipient hemorrhagic skin necrosis by timely administration of vitamin K1 in a woman treated with phenprocoumon is presented. From a critical review of the literature strong evidence emerges that coumarin necrosis does only occur in cases with severe initial drug induced hypocoagulability. Non- recognition thusfar of its importance is due to insufficient knowledge of the biological activities of thromboplastin preparations presently used in the laboratory control of oral anticoagulation. All well documented cases with apparently adequate Quick values were monitored with Faktor VIII insensitive thromboplastin. Therefore, such preparations should no longer be used in anticoagulant control.

Topics: 4-Hydroxycoumarins; Female; Hemorrhage; Humans; Middle Aged; Necrosis; Phenprocoumon; Skin; Skin Diseases; Thromboplastin; Vitamin K 1

Six trromboplastins commonly used for prothrombin time determinations were studied. Prothrombin times of patients who were receiving oral anticoagulant therapy varied widely, depending on the origin of the thromboplastins. The therapeutic range which is recommended with one thromboplastin is often quite different from that recommended with another, and as a result, the therapeutic ranges of different institutions may show no overlap. Management of patients and comparison of therapeutic results would be facilitated if all thromboplastins in use in Australia were standardized by comparison with the Australian Reference Thromboplastin.

Topics: Administration, Oral; Animals; Anticoagulants; Hemorrhage; Humans; Prothrombin Time; Rabbits; Reference Standards; Thromboplastin

We presented in this journal (Med. Klin. 71 [1976], 116), a procedure how to avoid hemorrhage risks due to heparine giving during hemo-dialyses. In this presentation is found the theoretical basis of the "minimal heparinisation". The practical carrying-out of the APTT (Activated Partial Thromboplastin Time)-control test as demonstrated by the 1200 bedside test cases, was done in order to give the personal without lab experience a practical guideline in the hand.

Topics: Blood Coagulation Tests; Blood Platelets; Centrifugation; Hemorrhage; Heparin; Humans; Thromboplastin; Time Factors

A prospective study using an intermittent six hour method of heparin administration with control of subsequent dosage by the activated partial thromboplastin time revealed an over-all incidence of hemorrhagic complications of 12 per cent. If surgical patients are excluded, the incidence of hemorrhage falls to 4 per cent. This may be further reduced by monitoring the activated partial thromboplastin time within the therapeutic range. In no patient did thromboembolism recur while receiving heparin. It is suggested that this method provides adequate control of heparin therapy with an acceptable complication rate and adequate thromboembolic control and is cheaper to use than a continuous infusion.

Topics: Adult; Aged; Blood Coagulation Tests; Female; Hemorrhage; Heparin; Humans; Infusions, Parenteral; Male; Middle Aged; Prospective Studies; Thrombophlebitis; Thromboplastin

A summarized account of our experiences over 1 1/2 years is given, in relation to a minimum heparinisation technique during haemodialysis. This novel technique was made possible by the introduction of an APTT bedside method. In a comparison between the techniques employed so far for preventing a heparin-caused risk of haemorrhage and our method, the clear advantage of our method was apparent. In addition to a discussion of our methods, we describe the cases treated so far. The amounts of heparin required for dialysis are so small that a necessary coagulation can occur even in a part of the organism where there is a danger of haemorrhage. Thereby it was possible to extend the range of indication for haemodialysis substantially. By using minimum heparinisation, it is possible to perform an immediate postoperative haemodialysis. The healing of wounds, which is impaired in cases of renal insufficiency, may be improved by early dialysis without the risk of haemorrhage. Our results show that the minimum heparinisation signifies a decisive achievement in acute dialysis therapy.

Topics: Acute Kidney Injury; Adult; Aged; Blood Coagulation Tests; Female; Hemorrhage; Heparin; Humans; Kidney Failure, Chronic; Male; Middle Aged; Monitoring, Physiologic; Renal Dialysis; Risk; Thromboplastin; Wounds and Injuries

This discussion has outlined several simple and reliable test systems which have been found useful in assessing disorders of hemostasis in the hemorrhaging CPB patient. When these tests are utilized as described in the preceding article, they have been extremely helpful in studying hemostasis in the CPB patient to be reexplored; they are equally helpful to quickly render a differential diagnosis of altered hemostasis when hemorrhage occurs. In addition, several "special" procedures, the AT-III and heparin assays, have been reviewed; these have been found quite useful in special instances of CPB hemorrhage, and community cardiovascular teams may wish them to be available. This paper has not presumed to be "authoritative" with respect to the "best" tests for assessing CPB hemostasis, but rather has offered only an approach helpful to the authors. The intent has, however, been to provide guidelines for instituting simple, reliable, and workable procedures for the community hospital where CPB is now routinely performed.

Topics: Antithrombins; Blood Coagulation Factors; Blood Coagulation Tests; Cardiopulmonary Bypass; Disseminated Intravascular Coagulation; Fibrin Fibrinogen Degradation Products; Fibrinolysin; Fibrinolysis; Hemorrhage; Hemostasis; Heparin; Humans; Plasminogen; Protamines; Thrombin; Thromboplastin

Four basic coagulation tests, the prothrombin time, thrombin time, partial thromboplastin time, and prothrombin consumption time, were used, with relatively simple modifications, to demonstrate the presence of two circulating anticoagulants in the blood of a patient with IgG myeloma and a severe bleeding tendency.

Topics: Antithrombins; Blood Coagulation Tests; Ear Diseases; Factor IX; Factor V; Factor VIII; Hemagglutination Inhibition Tests; Hematoma; Hemorrhage; Hot Temperature; Humans; Immunoelectrophoresis; Immunoglobulin G; Male; Melphalan; Middle Aged; Multiple Myeloma; Plasmapheresis; Prednisone; Prothrombin Time; Thromboplastin

Recovery of intrathoracic and intraperitoneal blood and reinfusion by autotransfusion has been demonstrated to be safe and practical in selected trauma patients. Autotransfusion is ideally applicable to the trauma patient in whom replacement of six or fewer units of blood is required. In addition, autotransfusion provides readily available blood for patients with unusual blood types and for those in whom multiple transfusions may rapidly deplete available stores. The properties of an ideal autotransfusion device include rapid assembly, relatively low cost, ease of operation, in-line filtration, minimized air blood interface, simplified anticoagulation, and safety from air embolism and coagulopathies.

Topics: Bilirubin; Blood Banks; Blood Cell Count; Blood Coagulation Tests; Blood Platelets; Blood Transfusion, Autologous; Fibrinogen; Hematocrit; Hemoglobins; Hemolysis; Hemorrhage; Humans; Leukocyte Count; Liver; Liver Function Tests; Postoperative Complications; Prothrombin Time; Thoracic Surgery; Thorax; Thromboplastin; Wounds and Injuries

Topics: Alkaline Phosphatase; Animals; Blood Coagulation; Blood Coagulation Tests; Bone and Bones; Calcium; Dogs; Female; Hematocrit; Hemorrhage; Heparin; Injections, Intravenous; Leukocyte Count; Minerals; Staphylococcus; Temperature; Thrombin; Thromboplastin; Time Factors

A study of 300 patients is presented to demonstrate the effectiveness of the activated plasma recalcification time (APRT) as a measure of the intrinsic pathway and platelet function in the detection of bleeders. The activated partial thromboplastin time (APTT) and platelet count were determined in all patients having both normal and abnormal APRT's and the results correlated with overt bleeding tendencies. Abnormality of the APTT is closely paralleled by abnormality of the APRT, independent of the platelet count. When the APTT is normal, an abnormal APRT will characterize clinical bleeders with greater frequency than will the platelet count. The value of the APRT is greatest when done in concert with other standard coagulation measurements, as it both reinforces and expands their diagnostic capability.

Topics: Adolescent; Adult; Blood Cell Count; Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Tests; Blood Platelets; Female; Hemorrhage; Humans; Male; Risk; Thromboplastin

Topics: Disseminated Intravascular Coagulation; Fibrinogen; Hemorrhage; Humans; Thromboplastin; Thrombosis

Topics: Blood Cell Count; Blood Coagulation; Blood Platelets; Blood Protein Disorders; Cholestasis; Diagnosis, Differential; Duodenal Neoplasms; Factor VII; Hemorrhage; Heparin; Humans; Liver Neoplasms; Neoplasm Metastasis; Pancreatic Neoplasms; Syndrome; Thromboplastin

Topics: Blood Coagulation; Blood Coagulation Tests; Clot Retraction; Disseminated Intravascular Coagulation; Half-Life; Hemorrhage; Hemostasis; Heparin; Humans; Infusions, Parenteral; Injections, Intravenous; Injections, Subcutaneous; Pulmonary Embolism; Thrombin; Thrombophlebitis; Thromboplastin; Time Factors

Topics: Aminocaproates; Extracorporeal Circulation; Fibrinogen; Fibrinolysis; Hemorrhage; Heparin; Humans; Methods; Protamines; Prothrombin Time; Sodium Chloride; Thromboplastin

Topics: Adolescent; Adult; Blood Coagulation; Blood Coagulation Tests; Child; Fibrinolysis; Hemorrhage; Humans; Myopia; Retina; Thrombin; Thromboplastin

Topics: Blood Coagulation Tests; Bone Marrow; Bone Marrow Cells; Bone Marrow Examination; Daunorubicin; Disseminated Intravascular Coagulation; Fibrinogen; Hemorrhage; Hemorrhagic Disorders; Hemostasis; Heparin; History, 20th Century; Humans; Leukemia, Myeloid, Acute; Thromboplastin

Topics: Aminocaproates; Animals; Blood Coagulation; Hemorrhage; Hemostatics; Peptide Hydrolases; Rats; Snakes; Thromboplastin; Venoms; Vitamin K; Wounds and Injuries

Topics: Alanine Transaminase; Aspartate Aminotransferases; Clot Retraction; Disability Evaluation; Epistaxis; Factor IX; Hemarthrosis; Hematuria; Hemophilia B; Hemorrhage; Hospitalization; Humans; Injections, Intravenous; Length of Stay; Prothrombin Time; Schools; Thrombelastography; Thromboplastin

Topics: Antithrombins; Blood Coagulation Disorders; Blood Coagulation Tests; Fibrinogen; Hemorrhage; Heparin; Humans; Methods; Phospholipids; Prothrombin Time; Temperature; Thrombelastography; Thrombin; Thromboplastin; Time Factors

Topics: Adult; Antibody Formation; Blood Cell Count; Blood Coagulation Tests; Blood Platelets; Complement Fixation Tests; Hemorrhage; Heparin; Humans; Male; Middle Aged; Myocardial Infarction; Platelet Adhesiveness; Prothrombin Time; Thrombocytopenia; Thromboembolism; Thromboplastin; Thrombosis

A prospective, randomized trial is described in which the usefulness of two tests in the control of anticoagulant therapy is compared. Fifty-two patients were controlled by the one-stage prothrombin time and 55 by the activated partial thromboplastin time. There was no significant difference in the incidence of bleeding between the two groups. When bleeding did occur, it was more often reflected by prolongation of the prothrombin time than of the activated partial thromboplastin time. The prothrombin time was found to have some practical advantages over the activated partial thromboplastin time.

Topics: Adult; Age Factors; Aged; Anticoagulants; Blood Coagulation Tests; Hemorrhage; Humans; Methods; Middle Aged; Prothrombin Time; Thromboembolism; Thrombophlebitis; Thromboplastin

Topics: Animals; Aorta; Blood Coagulation Factors; Blood Coagulation Tests; Endotoxins; Hemorrhage; Heparin; Infarction; Injections, Intra-Arterial; Injections, Intravenous; Kidney Cortex Necrosis; Leukocytes; Male; Myocardial Infarction; Peritoneum; Prothrombin Time; Pulmonary Embolism; Rabbits; Shwartzman Phenomenon; Thromboplastin; Thrombosis

Topics: Animals; Antifibrinolytic Agents; Blood Coagulation; Blood Coagulation Tests; Cyclohexanecarboxylic Acids; Drug Combinations; Hemorrhage; Male; Radiation Injuries, Experimental; Rats; Syndrome; Thromboplastin

Topics: Adolescent; Adult; Aged; Blood Coagulation Tests; Female; Hemorrhage; Heparin; Humans; Infusions, Parenteral; Male; Middle Aged; Prospective Studies; Pulmonary Embolism; Radiography; Radionuclide Imaging; Recurrence; Thromboembolism; Thrombophlebitis; Thromboplastin; Time Factors

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Blood Coagulation Factors; Blood Platelet Disorders; Blood Platelets; Dicumarol; Factor VII; Glycine max; Hemorrhage; Hemostatics; Humans; Pedigree; Phospholipids; Plasma; Prothrombin; Prothrombin Time; Rabbits; Thrombocytopenia; Thromboplastin; Vitamin K; Vitamin K Deficiency

Topics: Blood Cell Count; Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Platelet Disorders; Blood Platelets; Diagnosis, Differential; Disseminated Intravascular Coagulation; Female; Hemoglobinometry; Hemophilia A; Hemophilia B; Hemorrhage; Humans; Male; Prothrombin Time; Purpura; Purpura, Thrombocytopenic; Purpura, Thrombotic Thrombocytopenic; Rheumatic Diseases; Telangiectasia, Hereditary Hemorrhagic; Thromboplastin; von Willebrand Diseases

Topics: Adult; Antibodies; Factor VIII; Hemorrhage; Humans; Male; Prothrombin Time; Thromboplastin

Topics: Antibodies; Blood Coagulation; Blood Coagulation Factors; Exchange Transfusion, Whole Blood; Hematocrit; Hemorrhage; Humans; Male; Middle Aged; Postoperative Complications; Preoperative Care; Prostatectomy; Thromboplastin

Topics: Aminocaproates; Animals; Blood Coagulation Tests; Carbon Tetrachloride; Collagen; Hemorrhage; Hemostatics; Liver; Rats; Thromboplastin; Venoms; Vitamin K

Topics: Aneurysm; Cerebral Arterial Diseases; Creatinine; Dextrans; Factor VIII; Fibrinolytic Agents; Hemorrhage; Hemorrhagic Disorders; Humans; Kidney Diseases, Cystic; Male; Middle Aged; Platelet Adhesiveness; Prothrombin Time; Thrombin; Thromboplastin

Topics: Adenoma; Antithyroid Agents; Drug Synergism; Fibrinolysis; Goiter; Hematoma; Hemorrhage; Humans; Plasminogen; Postoperative Complications; Preoperative Care; Thromboplastin; Thyroid Gland; Thyroid Neoplasms

Topics: Adult; Afibrinogenemia; Blood Cell Count; Blood Coagulation Tests; Fibrinolysis; Hemorrhage; Humans; Leukemia, Myeloid, Acute; Male; Prothrombin Time; Thromboplastin

Topics: Aged; Anticoagulants; Antithrombins; Blood Coagulation Disorders; Factor VIII; Female; Hemophilia A; Hemorrhage; Hemorrhagic Disorders; Humans; Male; Middle Aged; Pregnancy; Pregnancy Complications, Hematologic; Thromboplastin

Topics: Adult; Antibodies; Antigens; Appendectomy; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Coagulation Tests; Blood Transfusion; Factor VII; Factor X; Female; Hematuria; Hemorrhage; Heterozygote; Humans; Hypoprothrombinemias; Immunodiffusion; Italy; Neutralization Tests; Pedigree; Phosphatidylethanolamines; Pregnancy; Pregnancy Complications, Hematologic; Puerperal Disorders; Thromboplastin; Tooth Extraction

Topics: Adrenalectomy; Animals; Blood Cell Count; Blood Platelets; Female; Hemorrhage; Hypophysectomy; Ligation; Male; Mice; Nephrectomy; Rats; Splenectomy; Thrombocytosis; Thromboplastin; Thrombopoietin; Ureter

Topics: Autopsy; Blood Cell Count; Blood Coagulation Factors; Blood Coagulation Tests; Blood Platelets; Blood Vessels; Cerebral Hemorrhage; Disseminated Intravascular Coagulation; Erythroblastosis, Fetal; Female; Fibrin; Fibrinogen; Hemoglobins; Hemorrhage; Humans; Infant, Newborn; Liver; Lung; Pregnancy; Retrospective Studies; Subarachnoid Hemorrhage; Thrombin; Thromboplastin

Topics: Adolescent; Adult; Blood Cell Count; Blood Coagulation; Blood Platelets; Body Temperature; Cardiac Surgical Procedures; Child; Child, Preschool; Esophagus; Extracorporeal Circulation; Female; Fibrinogen; Hemorrhage; Humans; Male; Platelet Adhesiveness; Postoperative Complications; Prothrombin Time; Thrombelastography; Thromboplastin

Topics: Blood Platelet Disorders; Blood Preservation; Freezing; Hemorrhage; Humans; Male; Military Medicine; Prothrombin Time; Thromboplastin; Transfusion Reaction

Topics: Animals; Blood Coagulation Disorders; Dextrans; Hemorrhage; Humans; Rabbits; Thrombin; Thromboplastin

Topics: Adipose Tissue; Aminocaproates; Animals; Anticoagulants; Antifibrinolytic Agents; Blood Coagulation Disorders; Brain; Embolism, Fat; Female; Fibrinolysis; Hemorrhage; Heparin; Injections, Intravenous; Intracranial Embolism and Thrombosis; Liver; Lung; Pulmonary Artery; Pulmonary Embolism; Pulmonary Veins; Radioactivity; Radioisotopes; Rats; Thromboplastin

Heparin therapy in 114 patients was controlled by daily blood tests-the whole blood coagulation time, kaolin-activated partial thromboplastin time of plasma, and plasma heparin assay. Bleeding episodes occurred in 7 out of 92 patients (7.6%) who had normal haemostatic mechanisms before therapy and in 11 out of 22 patients (50%) with defective haemostasis, mostly due to intravascular coagulation or renal failure. The dose of heparin ranged from 20,000 to 60,000 units in each 24-hour period. In some patients bleeding was related to overdosage, but in others the laboratory tests indicated satisfactory or suboptimal dosage at the time of bleeding. Though there were positive correlations between the results of the three tests, these were not close, and no one test was preferable. Hence laboratory control of heparin therapy is unsatisfactory and patients may bleed despite careful control of the dose by all three methods.

Topics: Acute Kidney Injury; Adult; Aged; Blood Coagulation Disorders; Blood Coagulation Tests; Female; Hemorrhage; Heparin; Humans; Kaolin; Male; Middle Aged; Thromboplastin

Topics: Blood Coagulation Tests; Chronic Disease; Factor VII; Hemorrhage; Hepatic Encephalopathy; Humans; Methods; Prothrombin Time; Thromboplastin

Topics: Animals; Anticoagulants; Blood Coagulation Disorders; Blood Vessels; Dogs; Fibrinolysis; Hematologic Diseases; Hemorrhage; Hemostasis; Humans; Postoperative Complications; Rabbits; Rats; Stress, Physiological; Stress, Psychological; Surgical Procedures, Operative; Thromboplastin; Transfusion Reaction

Intravenous injection of autologous lipoprotein (thromboplastin) or thrombin produced a lethal, hemorrhagic syndrome in chicken embryos. The embryos could be protected from this fatal result by injection of antithrombin III, an alpha(2)-globulin (molecular weight 60,000 to 80,000) purified from human, bovine, and guinea pig blood. Heparin also protected the embryos, but other inhibitors were less protective.

Topics: Alpha-Globulins; Animals; Antithrombins; Blood Protein Electrophoresis; Cattle; Chick Embryo; Electrophoresis, Disc; Guinea Pigs; Hemorrhage; Heparin; Humans; Injections, Intravenous; Molecular Weight; Thromboplastin

Topics: Aminocaproates; Aprotinin; Blood Platelet Disorders; Blood Platelets; Fibrinolysis; Hemorrhage; Humans; In Vitro Techniques; Male; Postoperative Complications; Prostatectomy; Prostatic Hyperplasia; Prostatic Neoplasms; Prothrombin Time; Thromboplastin

Topics: Aged; Anticoagulants; Blood Coagulation Disorders; Blood Coagulation Tests; Chromatography; Factor V; Factor VII; Factor X; Female; Femoral Neck Fractures; Hemorrhage; Humans; Prothrombin; Prothrombin Time; Thromboplastin; Time Factors

Topics: Arteriosclerosis; Blood Coagulation; Blood Coagulation Tests; Blood Platelets; Extracorporeal Circulation; Fibrin; Fibrinolysis; Hemorrhage; Heparin; Heparin Antagonists; Humans; Hyperlipidemias; Hypersensitivity; Natriuresis; Osteoporosis; Protamines; Prothrombin Time; Thromboembolism; Thrombophlebitis; Thromboplastin

Topics: Adenine Nucleotides; Aged; Blood Coagulation Factors; Blood Platelet Disorders; Bone Marrow Diseases; Carbon Isotopes; Cell Aggregation; Collagen; Epinephrine; Female; Hematocrit; Hemorrhage; Humans; Male; Microscopy, Electron; Middle Aged; Myeloproliferative Disorders; Phosphates; Serotonin; Sodium; Thromboplastin

Topics: Blood Coagulation; Blood Platelets; Hemorrhage; Microscopy, Electron; Models, Theoretical; Thromboplastin; Thrombosis; Wounds and Injuries

Topics: Anemia; Anticoagulants; Blood Cell Count; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Platelets; Blood Transfusion; Fibrinogen; Fibrinolysis; Hematologic Diseases; Hemorrhage; Humans; Infant, Newborn; Postoperative Complications; Preoperative Care; Prothrombin; Prothrombin Time; Thromboplastin

Topics: Adult; Blood Circulation Time; Blood Coagulation Disorders; Blood Coagulation Tests; Blood Platelets; Breast Neoplasms; Carcinoma; Factor XI; Factor XI Deficiency; Female; Hemorrhage; Hemorrhagic Disorders; Humans; Mastectomy; Methods; Microscopy, Phase-Contrast; Plasma Substitutes; Prothrombin Time; Thromboplastin

Topics: Abruptio Placentae; Adult; Aprotinin; Blood Coagulation; Blood Coagulation Tests; Blood Platelets; Factor V; Factor VIII; Female; Fibrinogen; Glass; Hemorrhage; Hemorrhagic Disorders; Humans; In Vitro Techniques; Middle Aged; Plasminogen; Postoperative Complications; Pregnancy; Prothrombin; Thrombin; Thromboplastin; Time Factors

Topics: Aprotinin; Hemorrhage; Humans; Neoplasms; Thromboplastin

Topics: Anticoagulants; Blood Coagulation; Coumarins; Drug Antagonism; Drug Synergism; Hemorrhage; Humans; Prothrombin Time; Thromboplastin

Topics: Adult; Blood Coagulation; Blood Coagulation Factors; Blood Coagulation Tests; Child; Child, Preschool; Contrast Media; Diatrizoate; Hemorrhage; Humans; Iodides; Iothalamic Acid; Male; Potassium Iodide; Prothrombin Time; Sodium; Thromboplastin

Topics: Aged; Arteries; Arteriosclerosis; Blood Coagulation Tests; Blood Platelets; Hemorrhage; Humans; Thrombin; Thromboplastin; Thrombosis

Topics: Adult; Cesarean Section; Female; Hemorrhage; Hemostasis; Humans; Obstetric Labor, Premature; Placenta; Pregnancy; Thromboplastin

Topics: Anticoagulants; Blood Coagulation Tests; Factor VIII; Hemophilia A; Hemorrhage; Humans; Male; Middle Aged; Thromboplastin

Topics: Adipose Tissue; Adolescent; Adult; Aged; Blood Coagulation; Bone Marrow; Brain Chemistry; Factor VIII; Female; Fracture Fixation; Fractures, Bone; Fractures, Spontaneous; Hematoma; Hemophilia A; Hemophilia B; Hemorrhage; Humans; Male; Middle Aged; Muscles; Plasma; Radiography; Thromboplastin

Topics: Absenteeism; Adolescent; Adult; Aminocaproates; Blood Coagulation Tests; Blood Transfusion; Child; Child, Preschool; Hemophilia A; Hemorrhage; Humans; Thromboplastin; Time Factors

Topics: Child; Child, Preschool; Factor VIII; Female; Hematoma; Hemophilia A; Hemophilia B; Hemorrhage; Humans; Infant; Infant, Newborn; Italy; Male; Thromboplastin; von Willebrand Diseases

Topics: Blood Coagulation Tests; Cataract; Cataract Extraction; Diagnosis, Differential; Hemophilia A; Hemorrhage; Humans; Male; Methods; Middle Aged; Postoperative Complications; Thromboplastin

Topics: Adolescent; Adult; Blood Coagulation Disorders; Blood Coagulation Tests; Child; Child, Preschool; Hemorrhage; Humans; Mass Screening; Middle Aged; Preoperative Care; Surgical Procedures, Operative; Thromboplastin

Topics: Ethyl Biscoumacetate; Hemorrhage; Heparin; Humans; Streptokinase; Thromboembolism; Thromboplastin

Topics: Anticoagulants; Blood Coagulation Disorders; Drug Therapy; Hemorrhage; Humans; Prothrombin Time; Thromboplastin

Topics: Blood Coagulation Tests; Factor XI; Factor XI Deficiency; Hemorrhage; Hemorrhagic Disorders; Humans; Postoperative Complications; Prothrombin Time; Thromboplastin

Topics: Animals; Blood Chemical Analysis; Blood Coagulation; Blood Coagulation Factors; Dogs; Electrocardiography; Embolism; Embryo, Mammalian; Embryo, Nonmammalian; Hemorrhage; Heparin; Injections, Intra-Arterial; Injections, Intravenous; Liver; Pathology; Pulmonary Embolism; Research; Spleen; Thromboplastin

Topics: Aminocaproates; Aminocaproic Acid; Anticoagulants; Antithrombins; Blood Coagulation Tests; Blood Platelets; Extracorporeal Circulation; Factor V; Factor VII; Factor VIII; Factor X; Fibrinogen; Fibrinolysis; Heart, Artificial; Hemorrhage; Hemostasis; Hemostatics; Humans; Perfusion; Physiology; Thromboplastin

Topics: Blood Transfusion; Hemorrhage; Humans; Postoperative Complications; Thromboplastin; Tooth Extraction

Topics: Aminocaproates; Aminocaproic Acid; Drug Therapy; Embolism; Factor V; Factor VIII; Fibrinogen; Fibrinolysis; Geriatrics; Hemorrhage; Humans; Male; Postoperative Complications; Prostatectomy; Prothrombin; Thromboplastin; Thrombosis; Toxicology

Topics: Anticoagulants; Blood Coagulation Disorders; Blood Coagulation Tests; Hemorrhage; Humans; Prothrombin Time; Syndrome; Thromboplastin

Topics: Blood Coagulation Tests; Hemorrhage; Hemostasis; Humans; Postoperative Complications; Preoperative Care; Thromboplastin

Topics: Aminocaproates; Aminocaproic Acid; Anticoagulants; Biomedical Research; Chloroform; Dicumarol; Dogs; Hemophilia A; Hemorrhage; Pharmacology; Research; Thromboplastin

Topics: Blood Coagulation Tests; Hematologic Diseases; Hemorrhage; Humans; Leukemia; Thrombocytopenia; Thromboplastin

Topics: Blood Coagulation Tests; Child; Hemophilia A; Hemorrhage; Humans; Research; Thromboplastin

Topics: Aminocaproates; Aminocaproic Acid; Animals; Blood Coagulation; Dogs; Fibrinolysin; Fibrinolysis; Hemorrhage; Hemostasis; Muscle, Skeletal; Muscles; Pharmacology; Research; Thromboplastin; Tourniquets

Topics: Blood Coagulation Disorders; Factor XI Deficiency; Gastrointestinal Hemorrhage; Hemorrhage; Humans; Thromboplastin

Topics: Afibrinogenemia; Female; Fibrin; Hemorrhage; Humans; Postpartum Hemorrhage; Postpartum Period; Pregnancy; Pregnancy Complications; Thromboplastin

Topics: Hemorrhage; Hemorrhagic Disorders; Humans; Partial Thromboplastin Time; Thromboplastin

Topics: Fibrinolysis; Hemorrhage; Humans; Male; Prostatectomy; Thromboplastin

Topics: Factor IX; Factor XI; Hemorrhage; Humans; Surgical Procedures, Operative; Thromboplastin

Topics: Abortion, Induced; Female; Flavonoids; Genitalia; Genitalia, Female; Gynecology; Hemorrhage; Hemostatics; Humans; Obstetrics; Pregnancy; Pregnancy Complications; Quercetin; Thromboplastin; Uterus; Vitamins

Topics: Female; Genitalia; Genitalia, Female; Gynecology; Hemorrhage; Hemostasis; Humans; Labor, Obstetric; Obstetrics; Pregnancy; Thromboplastin

Topics: Female; Hemorrhage; Humans; Lipoproteins; Placenta; Placental Extracts; Pregnancy; Pregnancy Complications; Thromboplastin

Topics: Biomedical Research; Hemorrhage; Humans; Nasal Surgical Procedures; Nose; Thromboplastin; Tonsillectomy

Topics: Blood Coagulation Factors; Factor XI; Hemophilia A; Hemorrhage; Humans; Medical Records; Thromboplastin; Tooth Extraction

Topics: Blood Coagulation Disorders; Hemorrhage; Hemorrhagic Disorders; Plasma; Thromboplastin

Topics: Afibrinogenemia; Amniotic Fluid; Factor Xa; Female; Fibrinogen; Hemorrhage; Hemorrhagic Disorders; Humans; Labor, Obstetric; Pregnancy; Thromboplastin; Work

Topics: Blood Coagulation Disorders; Hemophilia A; Hemophilia B; Hemorrhage; Hemorrhagic Disorders; Medicine; Thromboplastin

Topics: Factor XI Deficiency; Hemorrhage; Hemorrhagic Disorders; Thromboplastin

Topics: Blood Coagulation Tests; Hemorrhage; Hemostatics; Prothrombin; Thromboplastin

Topics: Animals; Collagen; Dogs; Hemorrhage; Humans; Menstrual Hygiene Products; Tampons, Surgical; Thromboplastin

Topics: Duodenum; Gastrointestinal Hemorrhage; Gelatin Sponge, Absorbable; Hemorrhage; Humans; Stomach; Thrombin; Thromboplastin

Topics: Gelatin Sponge, Absorbable; Hemorrhage; Humans; Thromboplastin

Topics: Animals; Gelatin; Hemorrhage; Humans; Male; Porifera; Prostate; Prostatectomy; Thromboplastin

Topics: Hemorrhage; Hemostasis; Thromboplastin; X-Rays

Topics: Animals; Cattle; Fibrin; Fibrin Foam; Hemorrhage; Thromboplastin

Topics: Factor V; Factor Xa; Hemophilia A; Hemorrhage; Humans; Thromboplastin

Topics: Blood Transfusion; Gelatin Sponge, Absorbable; Hemorrhage; Hemostatics; Humans; Peptic Ulcer Hemorrhage; Stomach Ulcer; Thrombin; Thromboplastin

Topics: Animals; Daboia; Hemorrhage; Hemostatics; Humans; Lecithins; Phosphatidylcholines; Protamines; Prothrombin; Snake Venoms; Thromboplastin; Venoms; Viper Venoms

A study was made of the clotting defect and the course of the malady in a group of male dogs with an inherited, sex-linked bleeding disease. The clotting defect is characterized by a prolonged clotting time and a delayed prothrombin utilization, and is corrected by the addition either of thromboplastin or of normal plasma. A plasma protein fraction, fraction I, also corrects the defect. The defect appears to be due to a deficiency of a plasma factor, which normally, in the presence of platelets, makes thromboplastin available in shed blood. The clotting anomaly appears to be identical with that found in human hemophilia. The hemostatic defect is characterized by repeated hemorrhages, usually without obvious relationship to trauma. Hemarthroses occur frequently and may result in permanent joint deformity. The animals usually die early in life from massive hemorrhage. Transfusions with normal blood or plasma correct the clotting defect and readily control the hemorrhagic phenomena. By the use of transfusions, these dogs have been reared to maturity.

Topics: Animals; Blood Transfusion; Dogs; Hemophilia A; Hemorrhage; Humans; Male; Thromboplastin

Topics: Hemorrhage; Hemorrhagic Disorders; Humans; Prothrombin; Serum; Thromboplastin