thromboplastin and Hemophilia-B

Wound healing involves a number of physiologic mechanisms including coagulation, inflammation, formation of granulation tissue, and tissue remodeling. Coagulation with robust thrombin generation leading to fibrin formation is necessary for wound healing. It is less clear if there is a requirement for ongoing coagulation to support tissue remodeling. We have studied wound healing in mice with defects in both the initiation (low tissue factor) and propagation (hemophilia B) phases. In hemophilia B mice, dermal wound healing is delayed; this delay is associated with bleeding into the granulation tissue. Mice can be treated with replacement therapy (factor IX) or bypassing agents (factor VIIa) to restore thrombin generation. If treated just prior to wound placement, mice will have normal hemostasis in the first day of wound healing. As the therapeutic agents clear, the mice will revert to hemophilic state. If the primary role of coagulation in wound healing is to provide a stable platelet/fibrin plug that is loaded with thrombin, then treating hemophilic animals just prior to wound placement should restore normal wound healing. The results from this study did not support that hypothesis. Instead the results show that restoring thrombin generation only at the time of wound placement did not improve the delayed wound healing. In preliminary studies on low tissue factor mice, there also appears to be a delay in wound healing with evidence of bleeding into the granulation tissue. The current data suggests that ongoing coagulation function needs to be maintained to support a normal wound healing process.

Topics: Animals; Blood Coagulation; Disease Models, Animal; Factor VIIa; Hemophilia A; Hemophilia B; Mice; Mice, Transgenic; Models, Biological; Signal Transduction; Thrombin; Thromboplastin; Wound Healing

Recombinant activated factor VIIa (rFVIIa) has many clinical applications for patients with congenital bleeding disorders and in a variety of clinical settings. Additional studies in the future are ongoing and should provide the clinical anesthesiologist an additional option during certain bleeding states. Specific recommendations as to timing of administration and frequent monitoring of ionized calcium status are suggested at this time. Optimization of fibrinogen levels, platelet levels, pH, and body temperature will enhance efficacy of rFVIIa.

Topics: Cerebral Hemorrhage; Factor VIIa; Hemophilia A; Hemophilia B; Humans; Postpartum Hemorrhage; Recombinant Proteins; Thromboplastin; Warfare; Wounds and Injuries

Recombinant activated coagulation factor VII (rFVIIa) was developed for the treatment of patients with hemophilia who have developed inhibitors against the factor they are missing. Hemophilia is a serious bleeding disorder and patients with hemophilia develop repeated spontaneous CNS, joint and muscle bleeding. Any trauma, even mild events, may cause life-threatening bleeding, and without treatment, these patients have a life expectancy of about 16 years. Thus, hemophilia can be regarded as a model of severe bleeding, and an agent capable of inducing hemostasis in severe hemophilia independent of the hemophilia proteins (FVIII or FIX) may also be effective in patients without hemophilia who experience serious bleeds. The availability of rFVIIa stimulated research on the role of FVII and tissue factor (TF) in the hemostatic process. As a result, a picture partly different from the one suggested by previous models has emerged. These previous models basically neglected the role of cells and cell membranes. The importance of platelets and platelet membrane phospholipids in hemostasis has been demonstrated, and the new concept of the hemostatic process, focusing on cell surfaces, has been outlined.

Topics: Cerebral Hemorrhage; Clinical Trials as Topic; Dose-Response Relationship, Drug; Factor VII Deficiency; Factor VIIa; Hemophilia A; Hemophilia B; Hemostatics; Infusions, Intravenous; Recombinant Proteins; Thromboplastin

Factor IX is a factor of the blood coagulation system. Its activation occurs on the surface of phospholipid membranes. It can be activated by the factor VIIa-TF (tissue factor)-Ca2+ complex via an extrinsic pathway and by factor XIa in the presence of Ca2+ via the intrinsic pathway of blood coagulation system activation. The activated factor IXa is a serine proteinase. The main function of the activated factor IXa in complex with factor VIIIa and phospholipids in presence of Ca2+ consists of the activation of factor X. Factor IX is synthesized in the liver and is subject to a number of posttranslational modifications including gamma-carboxylation, beta-hydroxylation, and glycosylation. It forms a subgroup of vitamin K-dependent plasma proteins including factors VII and X and protein C characterized by identical domain structures having high levels of homology. Factor IX consists of an NH2-terminal Gla domain, two epidermal growth factor (EGF)-like domains, and a C-terminal domain containing Ser in its active site. Factor IX deficiency in human plasma results in the disease known as hemophilia B.

Topics: Animals; Antithrombin III; Blood Coagulation; Endopeptidases; Factor IX; Factor VIIa; Factor XIa; Hemophilia B; Humans; Molecular Structure; Thromboplastin

To evaluate the mechanism responsible for the generation of factor VIIa in vivo, we measured the levels of this enzyme after administering purified factor IX concentrates to patients with hemophilia B. Their factor VIIa levels were initially very low and gradually increased to normal, but there were no significant changes in the generation of factor Xa or thrombin. The administration of 10 mu g/kg body weight of recombinant factor VIIa to patients with factor VII deficiency increased the circulating levels 35-fold, but this only resulted in normalization of the activation of factor IX and factor X. Our data indicate that factor IXa is primarily responsible for the basal levels of free factor VIIa in vivo, and that changes in free factor VIIa in the blood do not necessarily lead to alterations in factor X activation.

Topics: Factor IX; Factor VIIa; Hemophilia B; Humans; 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: Blood Coagulation; Blood Platelets; Blood Vessels; Collagen; Enzyme Activation; Factor IX; Factor VII; Factor X; Hemophilia A; Hemophilia B; Hemostasis; Humans; Kininogens; Monocytes; Muscle, Smooth, Vascular; Thrombin; Thromboplastin

Topics: Blood Coagulation Disorders; Blood Transfusion; Calcium; Factor V Deficiency; Factor VIII; Factor X Deficiency; Factor XI Deficiency; Factor XII Deficiency; Factor XIII Deficiency; Female; Hemophilia A; Hemophilia B; Humans; Hypoprothrombinemias; Male; Pedigree; 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: Acute Disease; Child; Clinical Trials as Topic; Factor VIII; Hemarthrosis; Hemophilia A; Hemophilia B; Humans; Male; Placebos; Prednisone; Thromboplastin

Topics: Blood Coagulation; Factor VIII; Hemophilia A; Hemophilia B; Humans; Thromboplastin; Tissue Distribution

Tissue factor pathway inhibitor-alpha (TFPI-α) is a Kunitz-type serine protease inhibitor, which suppresses coagulation by inhibiting the tissue factor (TF)/factor VIIa complex as well as factor Xa. In static plasma-phospholipid systems, TFPI-α thus suppresses both factor Xa and thrombin generation. In this article, we used a microfluidics approach to investigate how TFPI-α regulates fibrin clot formation in platelet thrombi at low wall shear rate. We therefore hypothesized that the anticoagulant effect of TFPI-α in plasma is a function of the local procoagulant strength-defined as the magnitude of thrombin generation under flow, due to local activities of TF/factor VIIa and factor Xa. To test this hypothesis, we modulated local coagulation by microspot coating of flow channels with 0 to 100 pM TF/collagen, or by using blood from patients with haemophilia A or B. For blood or plasma from healthy subjects, blocking of TFPI-α enhanced fibrin formation, extending from a platelet thrombus, under flow only at <2 pM coated TF. This enhancement was paralleled by an increased thrombin generation. For mouse plasma, genetic deficiency in TFPI enhanced fibrin formation under flow also at 0 pM TF microspots. On the other hand, using blood from haemophilia A or B patients, TFPI-α antagonism markedly enhanced fibrin formation at microspots with up to 100 pM coated TF. We conclude that, under flow, TFPI-α is capable to antagonize fibrin formation in a manner dependent on and restricted by local TF/factor VIIa and factor Xa activities.

Topics: Animals; Anticoagulants; Blood Coagulation; Blood Platelets; Coagulants; Collagen; Crosses, Genetic; Factor VIIa; Factor Xa; Female; Fibrin; Healthy Volunteers; Hemophilia A; Hemophilia B; Heterozygote; Humans; Lipoproteins; Male; Mice; Mice, Inbred C57BL; Perfusion; Thromboplastin; Thrombosis

Platelet- and fibrin-dependent thrombus formation is regulated by blood flow and exposure of collagen and tissue factor. However, interactions between these blood-borne and vascular components are not well understood.. Here, we developed a method to assess whole-blood thrombus formation on microspots with defined amounts of collagen and tissue factor, allowing determination of the mechanical properties and intrathrombus composition. Confining the collagen content resulted in diminished platelet deposition and fibrin formation at high shear flow conditions, but this effect was compensated by a larger thrombus size and increased accumulation of fibrin in the luminal regions of the thrombi at the expense of the base regions. These thrombi were more dependent on tissue factor-triggered thrombin generation. Microforce nanoindentation analysis revealed a significantly increased microelasticity of thrombi with luminal-oriented fibrin. At a low shear rate, fibrin fibers tended to luminally cover the thrombi, again resulting in a higher microelasticity. Studies with blood from patients with distinct hemostatic insufficiencies indicated an impairment in the formation of a platelet-fibrin thrombus in the cases of dilutional coagulopathy, thrombocytopenia, Scott syndrome, and hemophilia B.. Taken together, our data indicate that (1) thrombin increases the platelet thrombus volume; (2) tissue factor drives the formation of fibrin outside of the platelet thrombus; (3) limitation of platelet adhesion redirects fibrin from bottom to top of the thrombus; (4) a lower shear rate promotes thrombus coverage with fibrin; (5) the fibrin distribution pattern determines thrombus microelasticity; and (6) the thrombus-forming process is reduced in patients with diverse hemostatic defects.

Topics: Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Tests; Blood Flow Velocity; Blood Platelets; Case-Control Studies; Collagen; Elasticity; Fibrin; Hemophilia B; Humans; Regional Blood Flow; Thrombocytopenia; Thromboplastin; Thrombosis; Time Factors

Essentials Disorders of hemostasis can lead to delayed and defective wound healing. In hemophilia B (HB) mice, 7 days of Factor (F)IX or VIIa are needed to normalize wound healing. One dose of a highly active FVIIa variant (DVQ) restored normal wound closure time in HB mice. Coagulation factors with enhanced activity may acquire biological effects not due to hemostasis.. Introduction We have previously reported that hemophilia B (HB) mice have delayed healing of cutaneous wounds and alterations in wound histology. Administration of a single dose of either factor IX or recombinant activated FVII (rFVIIa) (NovoSeven) prior to wounding did not improve wound closure time or histology. The FVIIa analog DVQ (V158D, E296V and M298Q mutations) was designed to have higher tissue factor-independent activity than rVIIa. We hypothesized that a single dose of DVQ would be more effective in restoring wound healing in HB mice. Methods Cutaneous punch wounds were made on the backs of HB and wild-type mice, and the time to wound closure was monitored. HB mice were treated with a dose of rFVIIa (10 mg kg(-1) ) or DVQ (1 mg kg(-1) ) that corrected the tail bleeding time. Skin samples were taken at various time points after wounding, fixed, and stained, and the histology was examined. Results As previously reported, wound closure times in HB mice given one dose of rFVIIa were not improved over those in untreated HB mice. Surprisingly, healing times in HB mice treated with an equally hemostatic dose of DVQ were normalized to that in wild-type mice. However, DVQ did not correct all histologic abnormalities in HB mice. Conclusions As the doses of DVQ and rFVIIa were chosen to support comparable levels of hemostasis, our data suggest that the improved healing seen with DVQ is not solely attributable to its hemostatic activity. It is possible that the improved wound healing arises through the effect of DVQ on cell signaling mechanisms.

Topics: Administration, Topical; Animals; Bleeding Time; Disease Models, Animal; Factor IX; Factor VIIa; Genetic Variation; Hemophilia B; Hemostasis; Humans; Mice; Mutation; Recombinant Proteins; Thromboplastin; Wound Healing

Hemophilia B is an inherited X-linked recessive bleeding disorder, due to a defect in human factor IX (FIX). The main treatment for hemophilia B is replacement therapy using FIX concentrates. Prophylactic treatment in severe hemophilia B is very effective but is limited by cost issues. Production of a recombinant FIX (rFIX) with enhanced clotting activity, offering the possibility of fewer infusions and fewer costs with similar efficacy, is one of the current challenges for hemophilia B treatment. The present study focused on an important amino acid sequence known to be involved in the interaction of activated FIX (FIXa) with its cofactor, activated factor VIII (FVIIIa).. Using site-directed mutagenesis of glutamate E410 (c240, chymotrypsin numbering), four recombinant FIX-E410 (E410H, A, L and N) mutants were developed and produced by the human hepatoma cell line Huh-7.. The in-vitro clotting activity of mutant FIX molecules was 3 to 5-fold higher than wild-type recombinant FIX (FIX-WT). FIX-E410H compound showed the highest in-vitro procoagulant activity. Enhanced specific activity was confirmed using thrombin generation assay. FIX-E410H induced 5.2-fold higher thrombin generation than FIX-WT. In hemophilia B mice, we observed significantly higher in-vivo clotting activity and thrombin generating capacity with FIX-E410H compared to FIX-WT. We demonstrated that increased procoagulant activity of FIX-E410H was mainly explained by 2.5- fold enhanced affinity of the mutant for human FVIIIa.. We have engineered and characterized four improved FIX proteins with enhanced in-vitro and in-vivo activity. Future studies are required to evaluate the immunogenicity of FIX-E410.

Topics: Amino Acid Substitution; Animals; Blood Coagulation; Blood Coagulation Tests; Blood Platelets; Cell Line; Disease Models, Animal; Factor IX; Factor VIIa; Factor VIIIa; Factor XIa; Gene Expression; Hemophilia B; Humans; In Vitro Techniques; Male; Mice; Mice, Mutant Strains; Mutagenesis, Site-Directed; Recombinant Proteins; Thromboplastin

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

Thrombin, the final enzyme of blood coagulation, is a multifunctional serine protease also involved in the progression of cancer. Tumor cells may activate blood coagulation proteases through the expression of procoagulant activities. However, specific information about the thrombin generation potential of malignant tissues is lacking. In this study we applied a single global coagulation test, the calibrated automated thrombogram assay, to characterize the specific procoagulant phenotypes of different tumor cells.. Malignant hematologic cells (i.e. NB4, HEL, and K562) or solid tumor cells (i.e. MCF-7 breast cancer and H69 small cell lung cells) were selected for the study. The calibrated automated thrombo-gram assay was performed in normal plasma and in plasma samples selectively deficient in factor VII, XII, IX or X, in the absence or presence of a specific anti-tissue factor antibody. Furthermore, cell tissue factor levels were characterized by measuring antigen, activity and mRNA expression.. In normal plasma, NB4 induced the highest thrombin generation, followed by MCF-7, H69, HEL, and K562 cells. The anti-tissue factor antibody, as well as deficiencies of factors VII, IX and XII affected the thrombin generation potential of malignant cells to different degrees, allowing differentiation of the two different pathways of blood clotting activation - by tissue factor or contact activation. The thrombin generation capacity of NB4 and MCF-7 cells was tissue factor-dependent, as it was highly sensitive to inhibition by anti-tissue factor antibody and factor VII deficiency, while the thrombin generation capacity of H69, HEL and K562 was contact activation-dependent, as no thrombin was generated by these cells in factor XII-deficient plasma.. This study demonstrates that the calibrated automated thrombogram assay is capable of quantifying, characterizing, and comparing the thrombin generation capacity of different tumor cells. This provides a useful tool for understanding the key factors determining the global pro-coagulant profile of tumors, which is important for addressing specific targeted therapy for the prevention of thrombosis and for cancer.

Topics: Blood Coagulation Tests; Cell Line, Tumor; Factor X Deficiency; Factor XII Deficiency; Hemophilia B; Humans; Leukemia; Neoplasms; Thrombin; Thromboplastin

Hemophilia A and B are caused by deficiencies in coagulation factor VIII (FVIII) and factor IX, respectively, resulting in deficient blood coagulation via the intrinsic pathway. The extrinsic coagulation pathway, mediated by factor VIIa and tissue factor (TF), remains intact but is negatively regulated by tissue factor pathway inhibitor (TFPI), which inhibits both factor VIIa and its product, factor Xa. This inhibition limits clot initiation via the extrinsic pathway, whereas factor deficiency in hemophilia limits clot propagation via the intrinsic pathway. ARC19499 is an aptamer that inhibits TFPI, thereby enabling clot initiation and propagation via the extrinsic pathway. The core aptamer binds tightly and specifically to TFPI. ARC19499 blocks TFPI inhibition of both factor Xa and the TF/factor VIIa complex. ARC19499 corrects thrombin generation in hemophilia A and B plasma and restores clotting in FVIII-neutralized whole blood. In the present study, using a monkey model of hemophilia, FVIII neutralization resulted in prolonged clotting times as measured by thromboelastography and prolonged saphenous-vein bleeding times, which are consistent with FVIII deficiency. ARC19499 restored thromboelastography clotting times to baseline levels and corrected bleeding times. These results demonstrate that ARC19499 inhibition of TFPI may be an effective alternative to current treatments of bleeding associated with hemophilia.

Topics: Animals; Aptamers, Nucleotide; Bleeding Time; Blood Coagulation; Disease Models, Animal; Factor VIIa; Factor VIII; Factor Xa; Hemophilia A; Hemophilia B; Hemostasis; Humans; In Vitro Techniques; Lipoproteins; Macaca fascicularis; Recombinant Proteins; Thrombin; Thromboplastin

Carbon monoxide derived from carbon monoxide releasing molecules (CORMs) has been demonstrated to enhance normal plasma thrombus speed of growth and strength in vitro. We tested the hypothesis that tricarbonyldichlororuthenium (II) dimer (CORM-2) improves the velocity of formation and strength of hemophiliac plasma thrombi as determined by thrombelastography. Plasma deficient (<1% normal activity) in factor VIII (FVIII; n = 11 individuals), factor IX (FIX; n = 5 individuals) or factor VII (FVII; n = 4 individuals) was exposed to 0 or 100 micromol CORM-2, with coagulation initiated with tissue factor. Coagulation kinetics were monitored with thrombelastography for 15 min. Paired t-tests were used to analyze FVIII-deficient plasma results; relative change was used to describe the other plasma types tested. In FVIII-deficient plasma, CORM-2 exposure significantly (P < 0.05) increased the velocity of thrombus formation (84%) and strength (48%) compared with plasma not exposed to CORM-2. FXI-deficient clots demonstrated an increase in velocity of formation (63%) and strength (43%) after CORM-2 exposure. Lastly, CORM-2 exposure increased FVII-deficient plasma velocity of formation (45%) and strength (63%). CORM-2 markedly enhanced the velocity of clot growth and strength in hemophiliac plasma. These findings serve as the rationale to determine whether CORMs could be utilized as hemostatic agents.

Topics: Blood Coagulation; Carbon Monoxide; Drug Evaluation, Preclinical; Factor VII Deficiency; Hemophilia A; Hemophilia B; Hemostatics; Humans; In Vitro Techniques; Organometallic Compounds; Plasma; Prodrugs; Thrombelastography; Thromboplastin

Healing of skin wounds is delayed in hemophilia B (HB) mice. HB mice do not bleed excessively at wounding, yet rebleed hours to days later. Tissue factor (TF) expression is up-regulated by inflammatory cytokines and has been linked to angiogenesis. We hypothesized that impaired thrombin generation in HB leads to impaired TF expression following injury. Punch biopsies were placed on wild-type (WT) and HB mice. Tissues from wound sites were immunostained for TF. Blood vessels are normally surrounded by a coat of pericytes expressing TF. Surprisingly, within a day after wounding TF disappeared from around nearby vessels; returning after 8 days in WT and 10 days in HB mice. The granulation tissue filling the wound during healing also lacked TF around angiogenic vessels. Thus, perivascular TF expression is down-regulated during wound healing. This may prevent thrombosis of neovessels during angiogenesis but renders hemophiliacs vulnerable to hemorrhage during healing.

Topics: Animals; Biopsy; Disease Models, Animal; Down-Regulation; Factor X Deficiency; Gene Expression Regulation; Hemophilia B; Humans; Mice; Mice, Knockout; Skin; Thromboplastin; Wound Healing; Wounds and Injuries

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

Recombinant factor VIIa (rFVIIa) used for the treatment of hemophilia A or B patients with an inhibitor is hemostatically effective because it induces thrombin generation (TG), despite grossly impaired FVIII- and FIX-dependent amplification of FX activation. Tissue factor (TF) and or activated platelets were shown to be essential for the rFVIIa activity.. To evaluate the relative effects of TF and phospholipids on rFVIIa-induced TG in FVIII-, FIX- and FXI-deficient plasmas.. Phospholipids had an independent effect that was augmented by TF. The contribution of blood-borne TF in FVIII-, FIX- and FXI-deficient plasma to rFVIIa-induced TG was demonstrated by removing microparticles and use of anti-TF antibodies.. At increasing concentrations of rFVIIa, the dependence of rFVIIa-induced TG on TF declined, but the presence of phospholipids was essential. rFVIIa was also shown to activate purified FIX and FX in the presence of phospholipids and absence of TF. rFVIIa-induced TG was dramatically augmented in FVIII- or FIX-deficient plasma in which the level of FVIII or FIX was increased to 1 or 2 U dL(-1).. The data indicate that rFVIIa-induced TG is affected by TF, phospholipids, rFVIIa concentration, and the presence of FVIII and FIX.

Topics: Blood Platelets; Coagulation Protein Disorders; Dose-Response Relationship, Drug; Factor IX; Factor VII; Factor VIIa; Factor X; Factor XI Deficiency; Hemophilia A; Hemophilia B; Humans; Kinetics; Phospholipids; Plasma; Recombinant Proteins; Thrombin; Thromboplastin

This study was performed to evaluate the influences of phospholipids and recombinant factor VIIa (rFVIIa) on thrombin generation and clot formation in "acquired" hemophilia B.. A synthetic mixture corresponding to hemophilia A (SHA) and "acquired" hemophilia B blood (AHBB) manufactured in vitro by an anti-FIX antibody were used in this study. With 10 pmol/L tissue factor (TF), 10 nmol/L rFVIIa, and saturating phospholipid, established thrombin generation in SHA was similar to that observed in the presence of factor VIII and rFVIIa at physiological concentrations. At lower phospholipid concentrations, thrombin generation was delayed and reduced. With 5 pmol/L TF, contact pathway-inhibited AHBB clotted later than normal blood and showed reduced clot stability and thrombin generation. These parameters of effectiveness were increased by the addition of phospholipids to AHBB, which restored clot stability and increased thrombin generation. No correction of clot formation or thrombin generation was observed when rFVIIa and phospholipids were added to AHBB in the absence of TF.. The influence of rFVIIa is dependent on TF, and phospholipids substantially increase the hemostatic (or thrombotic) potential of rFVIIa/TF.

Topics: Blood Coagulation; Blood Donors; Blood Substitutes; Factor VIIa; Fibrinogen; Hemophilia B; Humans; Phosphatidylcholines; Phosphatidylserines; Phospholipids; Recombinant Proteins; Thrombin; Thromboplastin; Titrimetry; Whole Blood Coagulation Time

The influence of elevated platelet concentration and recombinant factor VIIa (rFVIIa) on thrombin generation at 5 pM tissue factor (TF) in a synthetic mixture corresponding to hemophilia B (SHB) and "acquired" hemophilia B blood (AHBB) produced in vitro by an antifactor IX antibody was evaluated. (a) Thrombin generation in SHB and AHBB was delayed and reduced; (b) with 10 nM rFVIIa or 5x normal platelets (10 x 10(8)/mL) SHB and AHBB showed a slight increase in thrombin generation; (c) in the absence of TF, almost no thrombin generation was detected in SHB and AHBB in the presence of 10 nM rFVIIa and 10 x 10(8)/mL activated platelets (5x normal); (d) with TF, 10 nM rFVIIa and 3-5x normal nonactivated platelets (6-10 x 10(8)/mL), thrombin levels approaching normal values were attained. FVIIa appears to function effectively and locally by the combined effect of TF expression and platelet accumulation at the site of a vascular lesion.

Topics: Blood Platelets; Cells, Cultured; Factor VII; Factor VIIa; Hemophilia B; Hemostasis; Humans; Kinetics; Models, Biological; Platelet Count; Recombinant Proteins; Thrombin; Thromboplastin

We studied the functional role of two mutations, Pro55Ser and Pro55Leu, located in the N-terminal Epidermal Growth Factor-like domain (EGF1) of coagulation factor (F) IX. Both mutations cause mild hemophilia B with habitual FIX coagulant activities of 10-12% and FIX antigen levels of 50%. We found that activation by FVIIa/TF and FXIa was normal for FIXPro55Ser, but resulted in proteolysis of FIXPro55Leu at Arg318-Ser319 with a concomitant loss of amidolytic activity, suggesting intramolecular communication between EGF1 and the serine protease domain in FIX. This was further supported by experiments using an anti-EGF1 monoclonal antibody. Activation of FX by FIXaPro55Ser was impaired in both the presence and the absence of phospholipid or FVIIIa, indicating that Pro55 is not directly involved in binding to FVIIIa. We also studied the effect of the two Pro55 mutations on Ca2+ affinity and found only small changes. Thus, the Pro55Ser mutation causes hemophilia primarily through to an impaired ability to activate FX whereas at least in vitro the Pro55Leu defect interferes with the activation of FIX.

Topics: Calcium; DNA Mutational Analysis; Epidermal Growth Factor; Factor IX; Factor IXa; Factor VIIa; Factor X; Hemophilia B; Humans; Male; Middle Aged; Mutation, Missense; Protein Structure, Tertiary; Thromboplastin

Exposure of blood to tissue factor (TF) activates the extrinsic (TF:FVIIa) and intrinsic (FVIIIa:FIXa) pathways of coagulation. In this study, we found that mice expressing low levels of human TF ( approximately 1% of wild-type levels) in an mTF(-/-) background had significantly shorter lifespans than wild-type mice, in part, because of spontaneous fatal hemorrhages. All low-TF mice exhibited a selective heart defect that consisted of hemosiderin deposition and fibrosis. Direct intracardiac measurement demonstrated a 30% reduction (P < 0.001) in left ventricular function in 8-month-old low-TF mice compared with age-matched wild-type mice. Mice expressing low levels of murine FVII ( approximately 1% of wild-type levels) exhibited a similar pattern of hemosiderin deposition and fibrosis in their hearts. In contrast, FIX(-/-) mice, a model of hemophilia B, had normal hearts. Cardiac fibrosis in low-TF and low-FVII mice appears to be caused by hemorrhage from cardiac vessels due to impaired hemostasis. We propose that TF expression by cardiac myocytes provides a secondary hemostatic barrier to protect the heart from hemorrhage.

Topics: Animals; Endomyocardial Fibrosis; Factor VII; Fibrinogen; Gene Expression; Genetic Predisposition to Disease; Hemophilia B; Hemorrhagic Disorders; Hemosiderin; Hemostasis; Humans; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Models, Biological; Muscle, Skeletal; Myocardium; Organ Specificity; Protein Structure, Tertiary; Recombinant Fusion Proteins; Thromboplastin; Ventricular Dysfunction, Left

The ability of factor VIIa to initiate thrombin generation and clot formation in blood from healthy donors, blood from patients with hemophilia A, and in anti-factor IX antibody-induced ("acquired") hemophilia B blood was investigated. In normal blood, both factor VIIa-tissue factor (TF) complex and factor VIIa alone initiated thrombin generation. The efficiency of factor VIIa was about 0.0001 that of the factor VIIa-TF complex. In congenital hemophilia A blood and "acquired" hemophilia B blood in vitro, addition of 10 to 50 nM factor VIIa (pharmacologic concentrations) corrected the clotting time at all TF concentrations tested (0-100 pM) but had little effect on thrombin generation. Fibrinopeptide release and insoluble clot formation were only marginally influenced by addition of factor VIIa. TF alone had a more pronounced effect on thrombin generation; an increase in TF from 0 to 100 pM increased the maximum thrombin level in "acquired" hemophilia B blood from 120 to 480 nM. Platelet activation was considerably enhanced by addition of factor VIIa to both hemophilia A blood and "acquired" hemophilia B blood. Thus, pharmacologic concentrations of factor VIIa cannot restore normal thrombin generation in hemophilia A and hemophilia B blood in vitro. The efficacy of factor VIIa (10-50 nM) in hemophilia blood is dependent on TF.

Topics: Adult; Blood Coagulation; Blood Coagulation Tests; Case-Control Studies; Dose-Response Relationship, Drug; Factor VIIa; Fibrinogen; Hemophilia A; Hemophilia B; Humans; Kinetics; Male; Models, Biological; 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

Recombinant factor VIII and factor IX concentrates, human-plasma-derived albumin, and samples from previously untreated patients with hemophilia were examined for the presence of TT virus (TTV) by using polymerase chain reaction testing. Blood samples from the patients were obtained prospectively before and every 3 to 6 months after therapy was begun. TTV was detected in 23.5% of the recombinant-product lots and 55.5% of the albumin lots tested. Only first-generation factor VIII recombinant concentrates stabilized with human albumin were positive for TTV, whereas all second-generation (human protein-free) concentrates were negative for the virus. In 59% of patients treated with either first- or second-generation recombinant factor concentrates, TTV infection developed at some point after the initial infusion. Infection with TTV in these patients before and after treatment did not appear to be clinically important. Thus, first-generation recombinant factor VIII concentrates may contain TTV and the source of the viral contamination may be human albumin.

Topics: Blood Transfusion; DNA, Viral; Drug Contamination; Hemophilia A; Hemophilia B; Humans; Recombinant Proteins; Thromboplastin; Torque teno virus

Gly-48 is in the conserved DGDQC sequence (residues 47-51 of human factor IX) of the first EGF (EGF-1)-like domain of factor IX. The importance of the Gly-48 is manifested by two hemophilia B patients; factor IXTainan and factor IXMalmo27, with Gly-48 replaced by arginine (designated IXG48R) and valine (IXG48V), respectively. Both patients were CRM+ exhibiting mild hemophilic episodes with 25% (former) and 19% (latter) normal clotting activities. We characterize both factor IX variants to show the roles of Gly-48 and the conservation of the DGDQC sequence in factor IX. Purified plasma and recombinant factor IX variants exhibited approximately 26%-27% normal factor IX's clotting activities with G48R or G48V mutation. Both variants depicted normal quenching of the intrinsic fluorescence by increasing concentrations of calcium ions and Tb3+, indicating that arginine and valine substitution for Gly-48 did not perturb the calcium site in the EGF-1 domain. Activation of both mutants by factor XIa appeared normal. The reduced clotting activity of factors IXG48R and IXG48V was attributed to the failure of both mutants to cleavage factor X: in the presence of only phospholipids and calcium ions, both mutants showed a 4 to approximately 7-fold elevation in Km, and by adding factor VIIIa to the system, although factor VIIIa potentiated the activation of factor X by the mutants factor IXaG48R and factor IXaG48V, a 2 to approximately 3-fold decrease in the catalytic function was observed with the mutant factor IXa's, despite that they bound factor VIIIa on the phospholipid vesicles with only slightly reduced affinity when compared to wild-type factor IXa. The apparent Kd for factor VIIIa binding was 0.83 nM for normal factor IXa, 1.74 nM for IXaG48R and 1.4 nM for IXaG48V. Strikingly, when interaction with the factor VIIa-TF complex was examined, both mutations were barely activated by the VIIa-TF complex and they also showed abnormal interaction with VIIa-TF in bovine thromboplastin-based PT assays. Taken together, our results suggest that mutations at Gly-48 altered the interaction of factor IX with its extrinsic pathway activator (VIIa-TF complex), its macromolecular substrate (factor X), and its cofactor (factor VIIIa).

Topics: Animals; Blood Coagulation; Cattle; Factor IX; Factor VII; Glycine; Hemophilia B; Humans; Point Mutation; Thromboplastin; Time Factors

Recombinant factor VIIa (rVIIa) has been reported to be clinically effective and safe in haemophilic patients with inhibitor antibodies. Compared to activated prothrombin complex concentrates the risk of thrombotic complications seems to be very low after rVIIa administration. Determination of free thrombin generation has been shown to identify hypercoagulability. Therefore, free thrombin and prothrombinase activity (Xa generation) were assessed after extrinsic activation of rVIIa supplemented factor VIII and factor IX deficient plasma. Free thrombin generation was also determined after supplementation of (activated) prothrombin complex concentrates. Addition of 150 U rVIIa/ml shortened the clotting times markedly in control, factor VIII, and factor IX deficient plasma. In contrast, free thrombin and Xa generation were not different in the absence or presence of 150 U rVIIa/ml. Addition of (activated) prothrombin complex concentrates resulted in a marked increase of free thrombin generation in all investigated plasmas. Although in vitro studies cannot reflect specific clinical circumstances our results support the notion that rVIIa does not induce a hypercoagulable state as sporadically observed after administration of (activated) prothrombin complex concentrates.

Topics: Blood Coagulation; Blood Coagulation Factors; Factor VIIa; Factor Xa; Hemophilia A; Hemophilia B; Humans; Platelet Activation; Prothrombin; Recombinant Fusion Proteins; Thrombin; Thromboplastin

The identification of the presence of antiphospholipid in plasma is recognised to be of diagnostic and prognostic importance in subjects with thrombotic disease, recurrent miscarriage or collagen vascular disorders. A number of coagulation assays are currently employed for the detection of lupus anticoagulant (LA), many of which are influenced by reagent dependent and methodological variables. In the present study lyophilised plasma samples from three subjects with "strong", "weak" and "absent" LA were tested in 220 centres. The most commonly used tests for LA were Activated Partial Thromboplastin Time (APTT), Dilute Russell Viper Venom Time (DRVVT) and Kaolin CLotting Time (KCT). Median DRVVT ratios were 1.75, 1.17 and 1.10 for the three samples. The presence of a strong LA was not detected by 4% of laboratories. The correct diagnosis was made by 94% of users of DRVVT and 85% of users of KCT. A weak LA was not detected by over half of centres. Correction was observed on addition of plasma and also in platelet neutralisation. The correct diagnosis was made by 37% of users of DRVVT and 27% of users of KCT. Lupus Anticoagulant was falsely considered to be present in a Factor IX deficient plasma by approximately one quarter of laboratories. Amongst users of DRVVT and KCT absence of LA in this sample was correctly reported by 73% and 69% of centres respectively. The accuracy of testing for LA in the present study is suboptimal and this is likely to have important clinical consequences. There is clearly a need for greater conformity in the selection and performance of LA tests to facilitate accurate diagnosis of this important group of disorders.

Topics: Antiphospholipid Syndrome; Blood Coagulation; Blood Coagulation Tests; Diagnosis, Differential; Embolism; Female; Hemophilia B; Heterozygote; Humans; Lupus Coagulation Inhibitor; Lupus Erythematosus, Systemic; Male; Partial Thromboplastin Time; Quality Control; Reproducibility of Results; Retinal Vessels; Thromboplastin; United Kingdom

Several enzymes can activate factor VII in vitro, but the protease responsible for generating factor VIIa in vivo has not been determined. Using recombinant tissue factor that has undergone a COOH-terminal truncation, a sensitive functional assay has been established for measuring plasma factor VIIa levels. To evaluate the mechanism responsible for the generation of factor VIIa in vivo, we measured the levels of this enzyme after administering purified concentrates of factor IX and factor VIII to patients with severe deficiencies of these clotting factors. In patients with hemophilia B, factor VIIa levels were initially reduced to 0.5 +/- 0.1 ng/mL and gradually increased to normal after infusing 100 U/kg of body weight (BW) of factor IX. Despite these increases, there were no significant changes in the generation of factor Xa or thrombin. In patients with hemophilia A, only a slight reduction in factor VIIa levels (2.5 +/- 1.3 ng/mL) was observed as compared with controls (3.3 +/- 1.1 ng/mL) and no significant changes were observed after factor VIII levels were normalized. The administration of recombinant factor VIIa (10 micrograms/kg BW) to patients with factor VII deficiency increased the mean circulating level of the enzyme to 118 ng/mL, but this only resulted in normalization of the levels of the activation peptides of factor IX and factor X. The above data indicate that factor IXa is primarily responsible for the basal levels of free factor VIIa generated in vivo (ie, in the absence of thrombosis or provocative stimuli) and that changes in the plasma concentrations of free factor VIIa in the blood do not necessarily lead to alterations in the extent of factor X activation.

Topics: Adolescent; Adult; Enzyme Activation; Factor IX; Factor IXa; Factor VIIa; Factor VIII; Factor Xa; Hemophilia A; Hemophilia B; Humans; Middle Aged; Recombinant Proteins; Thrombin; Thromboplastin

Topics: Animals; Brain Chemistry; Hemophilia B; Humans; Prothrombin Time; Rabbits; Thromboplastin

A subset of hemophilia B patients have a prolonged bovine-brain prothrombin time. These CRM+ patients are classified as having hemophilia Bm. The prolongation of the prothrombin time has been reported only with bovine brain (referred to as ox brain in some literature) as the source of thromboplastin; prothrombin times determined with thromboplastin from rabbit brain or human brain are not reported to be prolonged. Factor IX from a hemophilia Bm patient (factor IX Hilo) was isolated. The activity of factor IX Hilo was compared to that of normal factor IX in prothrombin time assays when the thromboplastin source was of bovine, rabbit, or human origin. Factor IX, either normal or Hilo, prolonged a prothrombin time regardless of the tissue factor source. However, unless thromboplastin was from a bovine source, this prolongation required high concentrations of factor IX. Further, factor IX normal was as effective as factor IX Hilo in prolonging the prothrombin time when rabbit or human thromboplastin was used. With bovine thromboplastin, factor IX Hilo was significantly better than factor IX normal at prolonging the prothrombin time. The amount of prolongation was dependent on the amount of factor IX Hilo added. In addition, the prolongation was dependent on the concentration of factor X present in the sample. The prothrombin time changed as much as 20 seconds when the factor X concentration was varied from 50% to 150% to normal (fixed concentration of factor IX Hilo). These results demonstrate the difficulty of classifying the severity of a hemophilia Bm patient based on the bovine brain prothrombin time unless both the factor IX and factor X concentrations are known.

Topics: Animals; Blood Coagulation; Cattle; Factor IX; Hemophilia B; Humans; Prothrombin Time; Rabbits; Thromboplastin

Hemophilia Bm, a variant of hemophilia B, results in a marked increase in the ox brain prothrombin time. Mutations known to cause hemophilia Bm occur at residue 180, 181, or 182 near the amino terminus of the heavy chain and at residue 311, 364, 368, 390, 396, or 397 near the activation site of factor IX (Giannelli et al., 1990). In this study we replaced factor IX residues 181, 182, and 390 in separate experiments by site-directed mutgenesis. Valine 181 was replaced by isoleucine or alanine, and valine 182 was replaced by alanine or glycine. Alanine 390 was replaced by valine or aspartic acid. Recombinant factor IXs were expressed in human kidney 293 cells and purified by absorption and elution from a conformational specific monoclonal antibody column. The results show that factor IX Bm is a function not only of the position of the mutated amino acid but also of the particular amino acid substituted. For example, when valine 181 or 182 was replaced by small hydrophobic amino acids (alanine and glycine), factor IXs were found to have significantly decreased clotting activity. Unlike the naturally occurring mutations (Val181 --> Phe181 or Val182 --> Leu182), however, the small amino acid replacements did not result in prolonged ox brain prothrombin times. Surprisingly, the Ala390 --> Asp390 exchange did not affect clotting activity or binding to the macromolecular inhibitor antithrombin III. The Ala390 --> Val390 exchange resulted in loss of both clotting activity and binding to antithrombin III. These results suggest that residue 390 is not directly involved in binding to antithrombin III.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Amino Acid Sequence; Animals; Binding Sites; Cattle; Cell Line; DNA; Factor IX; Factor IXa; Factor VIIa; Genetic Variation; Hemophilia B; Humans; Kidney; Kinetics; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Point Mutation; Protein Structure, Secondary; Recombinant Proteins; Thromboplastin; Transfection

We report a study on the importance of factor IX activation in thromboplastin-dependent coagulation in plasma. Diluted, CaCl2-containing thromboplastin solutions at constant phospholipid concentration were used to trigger the coagulation in plasma from patients with congenital factor IX and factor VIII deficiency in the presence and absence of added factors IX and VIII, and the generation of thrombin activity was monitored. When coagulation is triggered with the high thromboplastin concentrations normally used in clinical routine tests, the generation of thrombin activity in plasma of patients with congenital factor IX deficiency before and after reconstitution with purified factor IX appears identical. When, however, coagulation is triggered with low thromboplastin concentrations, a clear dependency of the generation of thrombin activity on the concentration of factor IX becomes evident at factor IX concentrations lower than 30 nM (about 40% clotting factor activity). Factor VIII is a compulsory cofactor for this factor IX activity because the prothrombinase activity at optimal factor IX concentration is still critically dependent upon the amount of factor VIII present. The lower the amount of thromboplastin, the higher the importance of factor IX and factor VIII activation in thromboplastin-dependent coagulation. This suggests a role of this pathway in pathophysiological thrombin formation.

Topics: Blood Coagulation; Hemophilia A; Hemophilia B; Humans; Phospholipids; Thrombin; Thromboplastin

Fibrin deposition and platelet thrombus dimensions on subendothelium were studied in four groups of patients with coagulation factor deficiencies. Five patients with factor VIII deficiency (APTT 120 +/- 8 sec) and three patients with factor IX deficiency (APTT 125 +/- 11 sec) were severe bleeders, whereas four patients with factor XII deficiency and seven with factor XI deficiency were either asymptomatic or only mild bleeders despite APTT values of 439 +/- 49 and 153 +/- 13 sec, respectively. Everted segments of deendothelialized rabbit aorta were exposed at a shear rate of 650 sec(-1) for 5 and 10 min to directly sampled venous blood in an annular chamber. Blood coagulation was evaluated by measuring fibrin deposition (percent surface coverage) on the subendothelium and post-chamber fibrinopeptide A levels; platelet thrombus dimensions on the subendothelium were evaluated by determining the total thrombus volume per surface area (using an optical scanning technique) and the average height of the three tallest thrombi. Consistent differences were observed among the patient groups for both the 5-min and 10-min exposure times. The larger of the 5- and 10-min exposure-time values was used to calculate group averages. Fibrin deposition in normal subjects was 81% +/- 5% surface coverage, and post-chamber fibrinopeptide A values were 712 +/- 64 ng/ml. Markedly decreased fibrin deposition and fibrinopeptide A levels were observed in factor VIII deficiency (2% +/- 1% and 102 +/- 19 ng/ml) and factor IX deficiency (11% +/- 7% and 69 +/- 11 ng/ml). In contrast, significantly higher values were obtained in patients deficient in factor XI (33% +/- 5% and 201 +/- 57 ng/ml) and factor XII (66% +/- 12% and 306 +/- 72 ng/ml). Differences in thrombus dimensions were also observed. In normal subjects, the value for thrombus volume and average height of the tallest thrombi were 8.3 +/- 1.3 cu micron/sq micron and 145 +/- 11 micron, respectively, and in patients were as follows: FVIII, 2.7 +/- 0.6 and 71 +/- 7; FIX, 4.5 +/- 1.8 and 88 +/- 14; FXI, 11.8 +/- 1.9 and 125 +/- 10; and FXII, 7.9 +/- 3.1 and 130 +/- 25. Platelet thrombus dimensions were normal in a patient with fibrinogen deficiency, indicating that the smaller thrombi in factor VIII and factor IX deficiencies were probably due to impaired evolution of thrombin rather than diminished fibrin formation.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Adolescent; Adult; Aged; Blood Coagulation Disorders; Blood Platelets; Endothelium; Factor XI Deficiency; Factor XII Deficiency; Female; Fibrin; Fibrinogen; Fibrinopeptide A; Hemophilia A; Hemophilia B; Humans; In Vitro Techniques; Male; Middle Aged; Partial Thromboplastin Time; Platelet Adhesiveness; Prothrombin Time; Thromboplastin

An abnormal blood coagulation factor IX has been isolated from the blood of a hemophilia B patient with a variant of the disease (hemophilia Bm) characterized by a normal concentration of factor IX antigen, negligible factor IX coagulant activity, and a prolonged prothrombin time with bovine tissue factor. The isolated protein (factor IXBm) had the same apparent molecular weight as normal factor IX (55,000) and the same mobility on two dimensional immunoelectrophoresis as normal factor IX. Factor IXBm underwent limited proteolysis induced by activated factor XI, in the presence of Ca2+ ions, or induced by the reaction product of tissue factor, factor VII and Ca2+ ions. A timecourse study showed that activated factor XI cleaved factor IXBm and factor IX at similar rates. However, in contrast to normal factor IX, the limited protelysis of factor IXBm did not generate procoagulant activity. In kinetic experiments purified factor IXBm behaved like a competitive inhibitor (Ki of 0.017 muM) of the activation of factor X by bovine tissue factor and factor VII. Normal factor IX was also found to inhibit the reaction but required a four-fold higher concentration to activate the same inhibitory effects as factor IXBm.

Topics: Animals; Cattle; Factor IX; Factor VII; Factor X; Hemophilia B; Humans; Kinetics; Thromboplastin

Topics: Blood Coagulation Tests; Diagnosis, Differential; Factor IX; Factor VIII; Hemophilia A; Hemophilia B; Humans; In Vitro Techniques; Thromboplastin

Topics: Adolescent; Adult; Blood Coagulation Tests; Child; Child, Preschool; Factor VIII; Female; Hemarthrosis; Hematoma; Hemophilia A; Hemophilia B; Humans; Infant; Male; Oral Hemorrhage; Thromboplastin; von Willebrand Diseases

Topics: Afibrinogenemia; Blood Coagulation Disorders; Blood Coagulation Tests; Factor V Deficiency; Factor VII Deficiency; Factor X Deficiency; Factor XI Deficiency; Factor XII Deficiency; Factor XIII Deficiency; Hemophilia A; Hemophilia B; Humans; Hypoprothrombinemias; Kaolin; Phosphatidylethanolamines; Prekallikrein; Prothrombin Time; Thrombin; Thromboplastin; von Willebrand Diseases

The coagulant of normal human saliva has been identified as tissue factor (thromboplastin, TF) by virtue of its ability to cause rapid coagulation in plasmas deficient in first-stage coagulation factors and to activate factor x in the presence of factor VII and by virtue of the fact that its activity is expressed only in the presence of factor VII and is inhibited by an antibody to TF. The TF is related to cells and cell fragments in saliva. Salivary TF activity has been found to be significantly reduced in patients taking warfarin. The decline in TF activity during induction of warfarin anticoagulation occurs during the warfarin-induced decline in vitamin-K-dependent clotting factor activity, as judged by the prothrombin time. The decrease in TF activity is not related to a reduction in salivary cell count or total protein content or to a direct effect of warfarin on the assay. It is hypothesized that the mechanism by which warfarin inhibits TF activity may be related to the mechanism by which it inhibits expression of the activity of the vitamin-K-dependent clotting factors. Inhibition of the TF activity may be involved in the antithrombotic effect of warfarin.

Topics: Factor VII; Factor VII Deficiency; Factor X; Factor XI Deficiency; Factor XII Deficiency; Freezing; Hemophilia A; Hemophilia B; Humans; Hyaluronoglucosaminidase; Prothrombin; Thromboplastin; Warfarin

The influence of different temperatures between 13 degrees C and 45 degrees C on coagulation factors in vitro was studied by measuring clotting time with the recalcification time, partial thromboplastin time (PTT), and thromboplastin time test. In all three tests the shortest clotting times were measured at a temperature of 40 degrees C. The relation between temperature and clotting time was similar in fresh plasma and in plasma which had been stored at a temperature of --20 degrees C before examination. However, in all tests stored plasma showed shorter coagulation times. Prolongation of coagulation time at 45 degrees C is caused by irreversible reduction of coagulation activity in the plasma. At the same time thromboplastin- and PTT-reagent are imparied in their coagulation acitvity by a temperature of 45 decrees C. In comparison to plasma obtained from healthy persons plasma from patients with hemophilia A or B or with v. Willebrand's disease reacted more sensitive to changes in temperature in the PTT test. The coagulation defect was definitely more pronounced at 27 degrees and 17 degrees C than at 37 degrees C. It was not possible to differentiate these three coagulopathies with the PTT test at 27 degrees and 17 degrees C.

Topics: Blood Coagulation; Blood Coagulation Tests; Freezing; Hemophilia A; Hemophilia B; Humans; Temperature; Thromboplastin; von Willebrand Diseases

Some problems involved in grading the severity of hemophilia were discussed. No definite correlation existed between the clinical severity of hemophilia and the results of coagulation tests (activity of deficient factors, whole blood clotting time, thromboplastin screening test). There was also no correlation between the presence or absence of oral bleeding or hemarthrosis and the test results. It was concluded that the clinical severity of the disease can be graded more reasonably on the basis of clinical hemorrhagic symptoms than according to the activity of deficient factors.

Topics: Blood Coagulation Tests; Factor IX; Factor VIII; Hemarthrosis; Hemophilia A; Hemophilia B; Humans; Oral Hemorrhage; Thromboplastin

Topics: Animals; Antibodies; Antigens; Cattle; Factor IX; Factor VII; Factor X; Female; Hemophilia B; Heterozygote; Humans; Male; Prothrombin Time; Sheep; Thromboplastin

Six commercially available reagents for the determination of the activated partial thromboplastin time have been evaluated and compared with respect to their sensitivity to the coagulation factors VIII, IX and XI and to their response to heparin. Some variation was observed among the reagents regarding their sensitivity to factor XI and even greater differences were obtained with factors VIII and IX. It was also clear that none of the reagents was sensitive to the same extent to the factors tested. The sensitivity to heparin shows considerable variation, in terms of time as well as mode of response to increasing heparin levels. In four reagents this response is linear, it is logarithmic in one and the remaining one is yet again different. It seems unlikely that any standardization of the APTT determination is at present possible with the reagents studied.

Topics: Factor XI Deficiency; Hemophilia A; Hemophilia B; Heparin; Humans; Indicators and Reagents; Thromboplastin; Time Factors

Thrombotest clotting times of mixtures of coumarin plasmas and normal plasma yielded a patterm similar to that observed in mixtures of plasma with congenital coagulation disorders and normal plasma. The presence of 10 or 20% of test plasma in the mixture failed to affect the clotting times which resulted in normal limits. The only exception to this rule was the hemophilia BM plasma. In this case even the presence of 10-20% of patient plasma in the mixture caused a prolongation of the clotting time. This indicates that no inhibitor is present in coumarin plasmas and in the plasma of congenital coagulation disorders of the prothrombin complex save for hemophilia BM plasma which does contain an inhibitor.

Topics: Acenocoumarol; Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Tests; Female; Hemophilia B; Humans; Male; Prothrombin; Thromboplastin; Warfarin

Topics: Adolescent; Blood Coagulation Tests; Child; Hemophilia A; Hemophilia B; Humans; Male; Thromboplastin

The use of the prothrombin complex products for the treatment of inhibitor patients is discussed in relation to our difficulty in identifying the effective therapeutic principle, as well as the factors responsible for thrombogenicity. It would appear that combination of factors is responsible for either or both therapeutic and thrombogenic phenomena. Possible intermediate or aggregate forms of the procoagulants are present in the products, protected from the neutralizing effects of antithrombin III.

Topics: Antithrombin III; Blood Coagulation; Factor IX; Factor V; Factor VII; Factor XI; Factor XII; Hemophilia B; Humans; Prothrombin; Prothrombin Time; Thrombin; Thromboplastin

Topics: Antigens; Blood Coagulation Tests; Factor IX; Female; Hemophilia B; Heterozygote; Humans; Male; Thromboplastin

A report is presented on the performance of the correction of PTT by means of factor VIII and IX deficiency plasma, which may be used at least one year, when preserved in liquid nitrogen. The method allows reliable, qualitative statements to be made about disturbances in the area of the coagulation factors VIII, IX, XI and XII; the small amount of time required for preparing and carrying out these works representing an essential advantage.

Topics: Blood Coagulation Tests; Diagnosis, Differential; Hemophilia A; Hemophilia B; Humans; Thromboplastin

Topics: Blood Coagulation; Calcium; Dose-Response Relationship, Drug; Factor IX; Factor X; Hemophilia A; Hemophilia B; Humans; Oxalates; Phospholipids; Prothrombin Time; Thromboplastin

Starting from a plasma used for producing cryoprecipitate a concentrate was gained by means of adsorption on DEAE cellulose, the factor IX activity of which was six to thirteen times higher than that of the original plasma. Even the factors X and II are enriched to the same extent approximately. In patients with haemophilia B the concentrate proved to be very efficient and compatible during surgical operations.

Topics: Blood Coagulation Factors; Chromatography, DEAE-Cellulose; Factor IX; Factor X; Hemophilia B; Humans; Methods; Prothrombin; Thrombin; Thromboplastin

Activated partial thromboplastin times (APTT's) performed with a semi-automated electrical-conductivity type of clot timer on plasmas from patients with hepatic disease and intravascular coagulation, and on warfarin or heparin therapy, were significantly lower than when done on the same plasmas with either a manual optical method or an automated optical-endpoint instrument. Results of APTT's done on normal plasmas by the three methods were not significantly different. Substitution of different activator-phospholipid reagents resulted in some variability in results, but these differences were less than those between the different done with both the electrical clot timer and the automated optical instrument on prepared plasmas containing 5.0 or 1.0% of factor II, V, VIII, IX, OR X revealed shorter times with the electrical clot timer only in the case of factor II- and factor V-deficient plasmas. APTT's done on normal plasmas to which 0.1 or 0.3 units per ml. of heparin had been added vitro also were shorter with the electrical clot itmer than the automatic optical instrument. Prothrombin times done on normal and abnormal control plasmas and on a series of plasmas from patients on warfarin therapy showed no significant difference between the two methods.

Topics: Autoanalysis; Blood Chemical Analysis; Blood Coagulation Tests; Erythrocyte Aggregation; Factor V Deficiency; Factor X Deficiency; Hemophilia A; Hemophilia B; Heparin; Hydrogen-Ion Concentration; Hypoprothrombinemias; Liver Diseases; Optics and Photonics; Phospholipids; Prothrombin Time; Thromboplastin; Time Factors; Warfarin

Reagents may be prepared from normal plasma and used with the prothrombin time and partial thromboplastin time tests to distinguish isolated defects of factors I, II, VII, VIII, IX, X, XI, or XII.

Topics: Adolescent; Adult; Aluminum Hydroxide; Blood Coagulation Disorders; Blood Coagulation Tests; Child; Child, Preschool; Factor XI Deficiency; Female; Hemophilia A; Hemophilia B; Humans; In Vitro Techniques; Kaolin; Male; Middle Aged; Phospholipids; Plasma; Prothrombin Time; Thromboplastin; Tromethamine; von Willebrand Diseases

A large kindred with combined deficiencies of factors VII and IX is presented. The deficiencies appeared to be independent and the data were not consistent with a diagnosis of haemophilia BM. The identification of mildly affected family members, including carriers of haemophilia B and heterozygotes for factor-VII deficiency, was facilitated by comparison with the 95% confidence interval of an age- and sex-matched control population. The bleeding patterns were those of mild to moderate haemophilia B and did not appear to have been modified by the presence of factor-VII deficiency.

Topics: Factor IX; Factor VII; Factor VII Deficiency; Hemophilia B; Humans; Male; Middle Aged; Pedigree; Prothrombin; Thromboplastin

Topics: Animals; Blood Coagulation Tests; Blood Transfusion; Cattle; Factor IX; Genetic Linkage; Hemophilia B; Humans; Male; Plasma; Prothrombin Time; Rabbits; Sex Chromosomes; Thrombelastography; Thromboplastin

Topics: Adolescent; Adult; Blood Coagulation Disorders; Child, Preschool; Culture Techniques; Factor VII; Factor X; Factor XI; Factor XI Deficiency; Factor XII; Female; Fibroblasts; Hemophilia A; Hemophilia B; Humans; Male; Middle Aged; Skin; Thromboplastin; von Willebrand Diseases

Topics: Blood Coagulation Tests; Hemophilia A; Hemophilia B; Humans; Indicators and Reagents; Methods; Thromboplastin

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: Blood Cell Count; Blood Coagulation Tests; Blood Platelets; Densitometry; Factor IX; Factor VIII; Fibrinogen; Hemophilia A; Hemophilia B; Humans; Nitrogen; Photometry; Prothrombin; Thromboplastin; Time Factors

Topics: Adenocarcinoma, Mucinous; Animals; Arginine; Blood Coagulation; Blood Coagulation Tests; Brain Chemistry; Bronchi; Chemical Precipitation; Disseminated Intravascular Coagulation; Esterases; Factor V Deficiency; Factor VII; Factor VII Deficiency; Factor X; Fibrinogen; Hemophilia B; Humans; Hypoprothrombinemias; Kaolin; Mucins; Mucus; Muramidase; Phospholipids; Prothrombin; Rabbits; Thromboplastin; Time Factors; Venoms

Topics: Blood Coagulation Factors; Blood Coagulation Tests; Chromatography, DEAE-Cellulose; Chromatography, Ion Exchange; Citrates; Factor IX; Factor VIII; Factor X; Hemophilia B; Humans; Pyrogens; Thrombin; Thromboplastin

Topics: Antibodies; Blood Coagulation Tests; Factor IX; Hemophilia B; Humans; Italy; Male; Middle Aged; Neutralization Tests; Pedigree; Prothrombin Time; Thromboplastin

Topics: Blood Cell Count; Blood Coagulation; Blood Coagulation Disorders; Blood Platelets; Factor XI; Factor XI Deficiency; Factor XII; Hemophilia B; Humans; Phosphatidylethanolamines; Prothrombin; Thromboplastin

Topics: Blood Coagulation Disorders; Blood Coagulation Tests; Factor VIII; Hemophilia A; Hemophilia B; Humans; Hypoprothrombinemias; Methods; Thromboplastin; Time Factors

Topics: Adult; Blood Coagulation Tests; Blood Protein Electrophoresis; Blood Transfusion; Factor IX; Factor VIII; Freeze Drying; Hemophilia A; Hemophilia B; Humans; Kaolin; Male; Thromboplastin

Topics: Adolescent; Adult; Aged; Animals; Blood Coagulation Tests; Cattle; Factor IX; Factor VII; Factor X; Female; Hemophilia A; Hemophilia B; Humans; Male; Middle Aged; Prothrombin Time; Rabbits; Rats; Thromboplastin

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: Blood Coagulation Disorders; Blood Coagulation Tests; Hemophilia A; Hemophilia B; Humans; Kaolin; Thromboplastin

Topics: Acid Phosphatase; Animals; Blood Coagulation Tests; Brain; Cells, Cultured; Centrifugation; Cytoplasmic Granules; Dogs; Factor V Deficiency; Factor VII Deficiency; Factor X; Factor XI Deficiency; Hemophilia B; In Vitro Techniques; Leukocytes; Micropore Filters; Peritoneal Cavity; Thromboplastin

Topics: Blood Coagulation; Blood Coagulation Factors; Blood Coagulation Tests; Blood Platelets; Endotoxins; Factor V Deficiency; Factor VII Deficiency; Factor VIII; Hemophilia B; Humans; Hypoprothrombinemias; Leukocyte Count; Leukocytes; Plasma; Serratia marcescens; Thromboplastin

Topics: Blood Platelets; Chromatography, DEAE-Cellulose; Factor IX; Factor VII; Factor VII Deficiency; Factor X; Hemophilia B; Humans; Methods; Neutralization Tests; Phenindione; Prothrombin; Prothrombin Time; Thromboplastin; Venoms

Topics: Antibodies; Blood Coagulation Tests; Brain; Chromosome Mapping; Factor IX; Genes, Recessive; Hemophilia B; Humans; Mutation; Neutralization Tests; Prothrombin Time; Sex Chromosomes; Thromboplastin

Topics: Adolescent; Anticoagulants; Blood Coagulation Disorders; Blood Coagulation Tests; Factor IX; Furosemide; Glucocorticoids; Hemophilia B; Humans; Immune Sera; Immunization; Immunoelectrophoresis; Male; Nephrotic Syndrome; Prednisone; Proteinuria; Prothrombin Time; Thromboplastin

Topics: Blood Coagulation; Blood Coagulation Factors; Blood Coagulation Tests; Factor V Deficiency; Factor VII Deficiency; Factor XI Deficiency; Factor XIII; Hemophilia B; Hemostasis; Humans; Leishmaniasis, Visceral; Phospholipids; Prothrombin Time; Thrombocytopenia; Thromboplastin

Topics: Blood Coagulation Tests; Blood Transfusion; Child; Factor IX; Hemophilia B; Humans; Injections, Intravenous; Male; Methods; Thromboplastin

Three patients with Christmas disease whose plasma was shown to have a prolonged one-stage prothrombin time with ox brain thromboplastin have been investigated. These patients have an inhibitor for the reaction between factor X, factor VII, and ox brain extract. The abnormal constituent responsible for this inhibitor appears to be factor IX whuch is functionally inactive but antigenically indistinguishable from normal factor IX. It is proposed that patients might be classified into haemophilia B(+) for patients with this defect (Christmas disease(+)) and haemophilia B(-) (Christmas disease(-)) for patients who have classical Christmas disease.

Topics: Animals; Antigens; Blood Coagulation Tests; Cattle; Factor IX; Factor VII; Factor X; Hemophilia B; Humans; Immunodiffusion; Prothrombin; Thromboplastin

Topics: Blood Coagulation Tests; Diagnosis, Differential; Factor IX; Factor VIII; Hemophilia A; Hemophilia B; Humans; Male; Methods; Prothrombin Time; Thromboplastin; von Willebrand Diseases

Topics: Blood Coagulation Disorders; Blood Coagulation Factors; Blood Coagulation Tests; Factor VIII; Hemophilia B; Humans; Hypoprothrombinemias; Kaolin; Methods; Prothrombin Time; Thromboplastin; Time Factors

Topics: Blood Coagulation Factors; Hemophilia A; Hemophilia B; Humans; Hypoprothrombinemias; Thromboplastin; Wiskott-Aldrich Syndrome

Topics: Child; Child, Preschool; Diagnosis, Differential; Hemophilia A; Hemophilia B; Humans; Male; Singapore; 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: Brain; Factor IX; Hemophilia B; Humans; In Vitro Techniques; Methods; Thromboplastin; Tissue Extracts

Topics: Blood Coagulation Disorders; Blood Coagulation Tests; Diagnosis, Differential; Hemophilia A; Hemophilia B; Humans; Prothrombin Time; Thromboplastin

Topics: Animals; Cattle; Dicumarol; Dogs; Factor VII Deficiency; Factor XI Deficiency; Fibrin; Hemophilia A; Hemophilia B; In Vitro Techniques; Prothrombin; Snakes; Thrombin; Thromboplastin; Time Factors; Tissue Extracts; Venoms; Vitamin K

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

Deficiencies of factor VIII (in haemophilia) and factor IX (in Christmas disease) prolong the partial thromboplastin time. If normal plasma is treated with alumina, the factor VIII remains but the factor IX is removed and can subsequently be recovered by elution of the alumina. If a long partial thromboplastin time is found on investigating a male patient whose history suggests a life-long bleeding disorder, the plasma may be retested after adding either alumina-adsorbed normal plasma or eluate. If the patient's partial thromboplastin time is shortened (relative to the control) by adding adsorbed normal plasma the patient is likely to be a haemophiliac; but if it is shortened by adding eluate then he is likely to have Christmas disease. Practical details for carrying out these manoeuvres are given and experiments on the validity of the test described.

Topics: Blood Coagulation Tests; Hemophilia A; Hemophilia B; Kaolin; Thromboplastin; Time Factors

Topics: Animals; Antithrombins; Blood Coagulation; Blood Coagulation Tests; Factor IX; Hemophilia B; Humans; Snakes; Thromboplastin; Venoms

Topics: Aged; Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Tests; Female; Fibrinolysis; Hemophilia B; Humans; Liver; Liver Cirrhosis; Male; Prothrombin Time; Thromboplastin

Topics: Adult; Factor IX; Factor VIII; Female; Greece; Health Surveys; Hemophilia A; Hemophilia B; Humans; Prothrombin Time; Thromboplastin

Topics: Blood Coagulation Tests; Counseling; Diagnosis; Factor VIII; Factor XI; Genetics, Medical; Hemophilia A; Hemophilia B; Humans; Statistics as Topic; Thromboplastin

Topics: Factor VIII; Hemophilia A; Hemophilia B; Humans; Medicine; Surgical Procedures, Operative; Thromboplastin

The partial thromboplastin time test provides a convenient and sensitive screening procedure for deficiencies of thromboplastic factors, especially factors VIII and IX. The test is carried out after preincubating the plasma for 10 minutes with kaolin, and Inosithin is used as a platelet substitute. The ;normal range' of the test has been estimated in terms of the differences encountered between random normal plasmas tested in pairs, because individual patients are usually tested against single control subjects. A patient's partial thromboplastin time should be regarded as abnormal if it is more than six seconds longer than the control time. In the diagnosis of haemophilia, patients' plasmas with concentrations of factor VIII as low as about 20% might be regarded as being within the range of normal, if the selected control subject's factor VIII happened to lie near the lower end of the normal range. When mild haemophilia is suspected, discrimination may be improved by diluting both the patient's and the control plasmas 1 in 20 in haemophilic plasma. With the test modified in this way the clotting time is prolonged, though the range of differences among normal subjects is unaltered, and plasmas with factor VIII concentrations below about 30%, i.e., in undiluted plasma, would be unlikely to be regarded as normal. The partial thromboplastin time may be similarly modified as a screening test for factor IX deficiency.Some clinical examples are reported.

Topics: Aged; Blood Coagulation Tests; Diagnosis; Factor VIII; Hemophilia A; Hemophilia B; Humans; Indicators and Reagents; Kaolin; Partial Thromboplastin Time; Plasma; Reference Values; Thromboplastin

Topics: Blood Platelets; Hemophilia B; Humans; In Vitro Techniques; Thromboplastin

Topics: Blood Coagulation Tests; Hemophilia B; Humans; Prothrombin Time; Thromboplastin

Topics: Anticoagulants; Blood Coagulation Tests; Factor VII; Hemophilia B; Humans; Partial Thromboplastin Time; Prothrombin Time; Thromboplastin; Toxicology

Topics: Biomedical Research; Blood Coagulation Factors; Catechols; Dihydroxyphenylalanine; Dopamine; Ellagic Acid; Factor VII Deficiency; Factor XII; Flavonoids; Gallic Acid; Hemophilia A; Hemophilia B; Humans; Lactones; Pharmacology; Prothrombin; Pyrogallol; Research; Serum Globulins; Tannins; Thrombin; Thromboplastin

Topics: Anemia; Exchange Transfusion, Whole Blood; Factor VII Deficiency; Factor VIII; Hemophilia B; Hemorrhagic Disorders; Humans; Hyperbilirubinemia; Hypoprothrombinemias; Infant; Infant, Newborn; Infant, Newborn, Diseases; Prednisone; Scalp; Skull Fractures; Thromboplastin; Vitamin K 1

Topics: Blood; Blood Coagulation Tests; Blood Platelets; Calcium; Calcium, Dietary; Hemophilia A; Hemophilia B; Humans; Pharmacology; Phosphatidylethanolamines; Research; Thrombin; Thromboplastin

Topics: Blood Platelet Disorders; Dicumarol; Drug Therapy; Factor V Deficiency; Factor VII Deficiency; Factor VIII; Factor XII; Hemophilia A; Hemophilia B; Hemorrhagic Disorders; Heparin; Humans; Hypoprothrombinemias; Prothrombin; Prothrombin Time; Serum Globulins; Thrombocytopenia; Thromboplastin

Topics: Blood Coagulation Tests; Diagnosis, Differential; Factor VIII; Hemophilia A; Hemophilia B; Humans; Methods; Thromboplastin

Topics: Anticoagulants; Blood Coagulation; Blood Coagulation Factors; Blood Coagulation Tests; Factor IX; Hemophilia B; Humans; Liver Cirrhosis; Research; Thromboplastin; Whole Blood Coagulation Time

Topics: Blood Coagulation; Blood Coagulation Tests; Factor VII Deficiency; Factor VIII; Hemophilia B; Hemorrhagic Disorders; Humans; Hypoprothrombinemias; Prothrombin Time; Thromboplastin

Topics: Adrenal Cortex Hormones; Blood Chemical Analysis; Child; Factor IX; Hemophilia A; Hemophilia B; Hepatitis; Hepatitis A; Humans; Infant; Infant, Newborn; Infant, Premature; Jaundice; Jaundice, Obstructive; Leukemia; Pharmacology; Physiology; Purpura; Thromboplastin

Topics: Blood Coagulation Tests; Delivery, Obstetric; Female; Hemophilia B; Humans; Pathology; Postpartum Period; Pregnancy; Puerperal Disorders; Thromboplastin; von Willebrand Diseases

Topics: Blood Coagulation Tests; Ether; Ethers; Factor IX; Hemophilia A; Hemophilia B; Humans; Plasma; Thromboplastin

Topics: Afibrinogenemia; Anticoagulants; Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Platelets; Calcium; Factor IX; Factor V; Factor VII; Factor VIII; Factor X; Female; Fibrinogen; Fibrinolysis; Hemophilia B; Humans; Hypoprothrombinemias; Physiology; Pregnancy; Pregnancy Complications; Pregnancy Complications, Cardiovascular; Prothrombin; Thromboplastin

Topics: Hemophilia A; Hemophilia B; Humans; Medical Records; Medicine; Thromboplastin

Topics: Ehlers-Danlos Syndrome; Hemophilia B; Humans; Thromboplastin

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

Topics: Complement Factor B; Factor IX; Hemophilia A; Hemophilia B; Humans; Immunologic Deficiency Syndromes; Metabolism, Inborn Errors; Plasma; Thromboplastin

Topics: Diagnosis, Differential; Hemophilia B; Hemorrhagic Disorders; Thromboplastin

Topics: Factor IX; Hemophilia A; Hemophilia B; Hemorrhagic Disorders; Medicine; Sex Chromosome Disorders; Thromboplastin

Topics: Diagnosis, Differential; Hematologic Diseases; Hemophilia A; Hemophilia B; Hemorrhagic Disorders; Medicine; Thromboplastin

Topics: Hemophilia A; Hemophilia B; Humans; Medicine; Sex Chromosome Disorders; Thromboplastin; von Willebrand Diseases

Topics: Hemophilia A; Hemophilia B; Thromboplastin; von Willebrand Diseases