fibrin and Hemophilia-B

Topics: Blood Coagulation Factors; Blood Platelets; Diagnosis, Differential; Factor VII Deficiency; Fibrin; Fibrinolysis; Hemophilia A; Hemophilia B; Hemorrhage; Humans; Hypoprothrombinemias; Prothrombin Time; Thrombin; Vitamin K Deficiency

Prothrombin complex concentrates (PCC), licensed for the treatment of hemophilia B, are known to carry a significant risk of thromboembolic complications. Although the reasons for thrombogenicity are not completely understood, several manufacturers have developed purified factor IX concentrates that contain negligible amounts of the other vitamin K-dependent factors. To evaluate whether or not the infusion of such a factor IX concentrate is followed by lesser activation of the hemostatic system than by the infusion of a PCC, we performed a series of coagulation assays on 11 hemophilia B patients before and after the administration of these two types of concentrate using a randomized cross-over design. The levels of prothrombin fragment F1 + 2, a sensitive measure of the in vivo cleavage of prothrombin by factor Xa, was significantly increased in plasma after PCC, but not after factor IX concentrate. Plasma fibrinopeptide A, a sensitive index of the enzymatic activity of thrombin on fibrinogen, also increased significantly after PCC but not after factor IX concentrate. The fragment B beta 15-42, a sensitive index of the enzymatic action of plasmin on fibrin II, did not change after either concentrate. There were also no differences in less sensitive coagulation measurements, such as plasma fibrinogen, antithrombin III, and fibrin monomers, nor in indices of platelet activation, such as beta-thromboglobulin and platelet factor 4. These findings show that the infusion of a purified factor IX concentrate can result in substantially less activation of the coagulation cascade than may be seen with PCC.

Topics: Adolescent; Adult; Antithrombin III; Blood Coagulation; Blood Coagulation Factors; Blood Coagulation Tests; Dose-Response Relationship, Drug; Factor IX; Fibrin; Fibrinogen; Hemophilia B; Hemostasis; Humans; Infusions, Intravenous; Middle Aged; Peptide Fragments; Prothrombin; Thrombin

The clot waveform analysis (CWA) provide valuable information beyond clotting time. The present study was planned to assess whether the activated partial thromboplastin time (aPTT)-CWA can differentiate between hemophilia A (HA), hemophilia B (HB), or hemophilia A with inhibitors (HAWI).. The aPTT-CWA was generated by an optical detection system (ACL-TOP™ 500 coagulation analyzer) and the other tests were performed as per instructions from the manufacturer in the kit.. A total of 75 samples (47-HA, 16-HAWI, and 12-HB) with prolonged aPTT were recruited. On analyzing the quantitative aPTT-CWA data of HA (non-inhibitors) and HB samples, the width of acceleration 1 [+] peak was the differentiating finding. Among the significant parameters, the second derivative [+] peak was lower in both mild and moderate HA, equating to HB. The time for the height of 1/2 fibrin formation and width of velocity was significantly higher in mild, moderate and severe HA. The study did not show any significant differentiating finding while comparing HAWI and hemophilia A non-inhibitors (HANI). In the subgroups of HAWI and HANI with aPTT <70 s and 70-100 s, the second derivative [+] peak (2A) was higher and the time for the height of 1/2 fibrin formation (1C) was lesser in HAWI.. The aPTT-CWA parameters may be supportive for the differentiation of hemophilia including its severity and the existence of inhibitors.

Topics: Blood Coagulation Tests; Fibrin; Hemophilia A; Hemophilia B; Humans; Partial Thromboplastin Time; Thrombosis

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

In prior microfluidic studies with haemophilic blood perfused over collagen, we found that a severe deficiency (<1% factor level) reduced platelet and fibrin deposition, while a moderate deficiency (1-5%) only reduced fibrin deposition. We investigated: (i) the differential effect of rFVIIa (0.04-20 nm) on platelet and fibrin deposition, and (ii) the contribution of the contact pathway to rFVIIa-induced haemophilic blood clotting. Haemophilic or healthy blood with low and high corn trypsin inhibitor (CTI, 4 or 40 μg mL(-1) ) was perfused over collagen at an initial venous wall shear rate of 100 s(-1) . At 100 s(-1) wall shear rate, where FXIIa leads to thrombin production without added tissue factor, FXI-deficient blood (3%) or severely FVIII-deficient blood (<1%) produced no fibrin at either CTI level. Whereas rFVIIa potently enhanced platelet deposition, fibrin generation was not rescued. Distinct from the high CTI condition, engagement of the contact pathway (low CTI) in moderately FVIII-deficient (3%) or moderately FIX-deficient blood (5%) resulted in enhanced platelet and fibrin deposition following 4 nm rFVIIa supplementation. In mildly FVIII-deficient blood (15%) at <24 h since haemostatic therapy, rFVIIa enhanced both platelet and fibrin generation in either CTI condition although fibrin was produced more quickly and abundantly in low CTI. For tissue factor-free conditions of severe haemophilic blood clotting, we conclude that rFVIIa reliably generates low levels of 'signaling' thrombin sufficient to enhance platelet deposition on collagen, but is insufficient to drive fibrin polymerization unless potentiated by the contact pathway.

Topics: Blood Coagulation; Blood Coagulation Tests; Blood Platelets; Case-Control Studies; Collagen; Factor VIIa; Factor XI Deficiency; Fibrin; Hemophilia A; Hemophilia B; Humans; Microfluidic Analytical Techniques; Platelet Activation; Platelet Adhesiveness; Protein Binding; Recombinant Proteins

Factor IX (FIX) deficiency results in haemophilia B and high dose recombinant activated factor VII (rFVIIa) can decrease bleeding. Previously, we showed that FIX deficiency results in a reduced rate and peak of thrombin generation. We have now used plasma and an in vitro coagulation model to examine the effect of these changes in thrombin generation on fibrin clot structure and stability. Low FIX delayed the clot formation onset and reduced the fibrin polymerisation rate. Clots formed without FIX were composed of thicker fibrin fibres than normal. rFVIIa shortened the clot formation onset time and improved the fibre structure of haemophilic clots. We also examined clot formation in the presence of a fibrinolytic challenge by including tissue plasminogen activator or plasmin in the reaction milieu. In these assays, normal FIX levels supported clot formation; however, clots did not form in the absence of FIX. rFVIIa partially restored haemophilic clot formation. These results were independent of the effects of the thrombin-activatable fibrinolysis inhibitor. Our data suggest that rFVIIa enhances haemostasis in haemophiliacs by increasing the thrombin generation rate to both promote formation of a structurally normal clot and improve clot formation and stability at sites with high endogenous fibrinolytic activities.

Topics: Blood Coagulation; Cell Culture Techniques; Drug Administration Schedule; Factor IX; Factor VIIa; Fibrin; Fibrinolysin; Hemophilia B; Hemostasis; Hemostatics; Humans; Microscopy, Electron, Scanning; Nephelometry and Turbidimetry; Recombinant Proteins; Thrombin; Tissue Plasminogen Activator

Patients with hemophilia have an impaired thrombin generation and therefore form loose fibrin hemostatic plugs that are easily dissolved by fibrinolysis. This prevents maintained hemostasis in these patients, resulting in a severe bleeding disorder. Recombinant (F)VIIa has been shown to enhance thrombin generation on already thrombin-activated platelets in the absence of FVIII and FIX. An efficacy rate of 80-90% has been found in hemophilia patients with inhibitors against FVIII or FIX both in association with major surgery and in the treatment of serious bleedings. In a model measuring fibrin clot permeability in a platelet-containing system described by Blombäck et al. (1994) this was demonstrated to be dependent on the concentration of FVIII and FIX. The addition of rFVIIa in concentrations of 1.9, 4.8 and 9.6 microg mL(-1) normalized fibrin clot permeability. The concentration of 1.9 microg mL(-1) of rFVIIa normalized clot permeability in this system and the higher concentrations of rFVIIa added only slightly to the effect. No further decrease in clot permeability was found when rFVIIa in a concentration of 1.9 microg mL(-1) was added to a sample with a normal concentration (100%) of FVIII or FIX. Higher concentrations of rFVIIa added to the plasma containing 100% of FVIII or FIX induced only a slight further decrease of fibrin permeability constant, arguing against any unwanted effect of extra rFVIIa on clot permeability in the case of a normal hemostasis. Furthermore, the fibrin network was studied with 3D microscopy and the loose network found in the absence of FVIII or FIX increased in density with increasing FVIII or FIX concentrations. The addition of rFVIIa to FVIII- or FIX-deficient systems altered the network structure, making the fibers thinner and more tightly packed.

Topics: Blood Coagulation; Cells, Cultured; Dose-Response Relationship, Drug; Factor IX; Factor VII; Factor VIIa; Factor VIII; Fibrin; Hemophilia A; Hemophilia B; Humans; Models, Biological; Permeability; Porosity; Recombinant Proteins

After the formation of a platelet-plug, generation of fibrin is necessary for its stabilization. Both congenital and acquired deficiencies of clotting factors occur, leading to retarded formation of fibrin. In congenital disorders, preoperative correction is possible and necessary. In acquired deficiencies, the type and feasibility of correction depends on the cause of the deficiency.

Topics: Blood Coagulation Disorders; Fibrin; Hemophilia A; Hemophilia B; Hemostasis, Surgical; Humans; Vitamin K Deficiency; von Willebrand Diseases

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

Systemic hemostatic agents are reviewed. Among the agents discussed are vitamin K preparations (phytonadione, menadione, menadione sodium bisulfite, menadiol sodium diphosphate); and blood products (whole blood, plasma, cryoprecipitate, factor VIII concentrates, factor IX concentrates and fibrinogen concentrates). Normal and abnormal hemostasis and fibrinolysis are discussed, as is the general management of systemic hemostatic defects. Specific disorders covered are clotting factor deficiencies, hemophilia A, factor VIII inhibitors, von Willebrand disease, hemophilia B (Christmas disease), other congenital coagulation disorders, acquired deficiency of factors II, VII, IX and X, and defibrination syndrome.

Topics: Antibodies; Blood Coagulation Disorders; Factor VIII; Fibrin; Fibrinolysis; Hemophilia A; Hemophilia B; Hemostasis; Hemostatics; Humans; Transfusion Reaction; von Willebrand Diseases

Topics: Afibrinogenemia; Blood Coagulation Disorders; Blood Coagulation Factors; Factor IX; Factor VII; Factor VIII; Factor X; Factor XIII; Fibrin; Fibrinogen; Hemophilia A; Hemophilia B; Humans; Prothrombin; Thrombin; Vitamin K

Topics: Blood Coagulation; Blood Viscosity; Fibrin; Hemophilia A; Hemophilia B; Humans; Kinetics; Multiple Sclerosis; Parkinson Disease; Polymers; Thrombelastography

Topics: Animals; Blood Coagulation; Blood Platelets; Cell Membrane Permeability; Cytoplasm; Dogs; Fibrin; Hemophilia A; Hemophilia B; Microscopy, Electron; Organoids; Time Factors

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