fibrinopeptide-b and Thrombosis

Endothelial cells (EC) interact with fibrin at sites of vascular injury, thrombosis, inflammation and tumor growth, whereas they are quiescent when exposed to circulating fibrinogen. To determine the structural basis for specific interaction with fibrin we have characterized the response of EC to fibrin of varying structure. Fibrin was prepared with thrombin, which cleaves both fibrinopeptide A (FPA) and fibrinopeptide B (FPB), with Reptilase, which cleaves only FPA, and with contortrix procoagulant to cleave only FPB. Fibrin with FPB cleavage stimulated release of von Willebrand factor from EC Weibel-Palade bodies and also supported cell spreading. Involvement of the amino terminus of the fibrin beta chain in the response was shown by stimulation of von Willebrand factor release by the peptide beta 15-42. Also, fibrin prepared from a fibrinogen derivative lacking residues 15-42 of the beta chain failed to support EC spreading. EC adhesion was unaffected by the pattern of fibrinopeptide cleavage or by the removal of peptide beta 15-42 from fibrin. The results indicate that separate sites on the fibrin molecule mediate adhesion and spreading, and that the latter requires cleavage of FPB and the new amino terminus of the beta chain. They further suggest that cellular responses to fibrin are regulated by the proteolytic cleavages and conformational changes that convert fibrinogen to fibrin and may also be modulated by plasmic or elastase degradation.

Topics: Amino Acid Sequence; Animals; Cell Adhesion; Endothelium, Vascular; Fibrin; Fibrinogen; Fibrinopeptide A; Fibrinopeptide B; Humans; Inflammation; Macromolecular Substances; Molecular Sequence Data; Neoplasms; Platelet Adhesiveness; Thrombosis; von Willebrand Factor

Topics: Antithrombin III; beta-Thromboglobulin; Blood Platelets; Cell Survival; Fibrin Fibrinogen Degradation Products; Fibrinopeptide A; Fibrinopeptide B; Glycoproteins; Humans; Peptide Fragments; Platelet Aggregation; Platelet Factor 4; Protein C; Thrombosis

Topics: Animals; Antithrombin III Deficiency; Blood Coagulation; Blood Coagulation Disorders; Diabetes Complications; Estrogens; Female; Fibrinopeptide B; Hemostasis; Humans; Male; Myocardial Infarction; Neoplasms; Partial Thromboplastin Time; Postoperative Complications; Pregnancy; Prospective Studies; Thrombosis

Topics: alpha 1-Antitrypsin; alpha-Macroglobulins; Antithrombins; Blood Coagulation; Blood Coagulation Factors; Blood Platelets; Cell Survival; Factor V; Factor VII; Factor VIII; Factor XII; Fibrin; Fibrin Fibrinogen Degradation Products; Fibrinogen; Fibrinolysis; Fibrinopeptide A; Fibrinopeptide B; Humans; Kinetics; Liver; Mononuclear Phagocyte System; Platelet Aggregation; Thrombosis

To explore the effect(s) of growth hormone signaling on thrombosis, we studied signal transduction and transcription factor 5 (STAT5)-deficient mice and found markedly reduced survival in an in vivo thrombosis model. These findings were not explained by a compensatory increase in growth hormone secretion. There was a modest increase in the activity of several procoagulant factors, but there was no difference in the rate or magnitude of thrombin generation in STAT5-deficient mice relative to control. However, thrombin-triggered clot times were markedly shorter, and fibrin polymerization occurred more rapidly in plasma from STAT5-deficient mice. Fibrinogen depletion and mixing studies indicated that the effect on fibrin polymerization was not due to intrinsic changes in fibrinogen, but resulted from changes in the concentration of a circulating plasma inhibitor. While thrombin-triggered clot times were significantly shorter in STAT5-deficient animals, reptilase-triggered clot times were unchanged. Accordingly, while the rate of thrombin-catalyzed release of fibrinopeptide A was similar, the release of fibrinopeptide B was accelerated in STAT5-deficient plasma versus control. Taken together, these studies demonstrated that the loss of STAT5 resulted in a decrease in the concentration of a plasma inhibitor affecting thrombin-triggered cleavage of fibrinopeptide B. This ultimately resulted in accelerated fibrin polymerization and greater thrombosis susceptibility in STAT5-deficient animals.

Topics: Animals; Blood Coagulation; Disease Models, Animal; Factor XIII; Fibrin; Fibrinopeptide B; Immunoblotting; Mice; Mice, Inbred C57BL; Mice, Knockout; Pulmonary Embolism; Signal Transduction; STAT5 Transcription Factor; Thrombin Time; Thrombosis

The role of active thrombosis in the pathophysiology of pulmonary embolism is unclear. We tested the hypothesis that venous thrombi significantly increase their thrombotic activity once they embolize into the high-flow circulation of the pulmonary arteries. Thrombotic activity was measured using an immunoassay that measures both fibrinopeptide B (FPB) as well as its most abundant metabolite des-arginine FPB. Thrombi were formed in the femoral veins of adult dogs. In one group, the thrombi were embolized without anticoagulation. In the second group, heparin (300 U/kg bolus, then 90 U x kg(-1) x h(-1) infusion) was administered before embolization to prevent subsequent thrombotic activity. Plasma FPB concentrations were significantly suppressed in the heparinized group relative to the nonheparinized group for 1 h postembolization (P = 0.038). We conclude that pulmonary embolization itself causes preexisting venous thrombi to greatly intensify their thrombotic activity and that embolization-associated thrombus propagation can be prevented by heparin.

Topics: Ancrod; Animals; Anticoagulants; Dogs; Fibrinogen; Fibrinopeptide B; Heparin; Humans; Male; Pulmonary Embolism; Thromboembolism; Thrombosis

We report the first direct detection of a fibrinogen mutation by electrospray ionisation mass spectrometry. The propositus, from a family with a history of thrombosis, came to attention after a pulmonary embolism subsequent to a spontaneous abortion. Prolonged thrombin (41 s) and reptilase times (26 s) together with an impairment of fibrinopeptide B release suggested a mutation at the thrombin cleavage site of the Bbeta chain. Direct mass analysis of purified fibrin chains from a thrombin induced clot showed that 50% of the Bbeta chains remained uncleaved. The measured mass of the mono sialo isoform of this uncleaved chain was 54150 Da, compared to a value of 54198 Da for normal Bbeta chains. This decrease of 48 Da in the intact protein is indicative of either a Bbeta 14 Arg to Cys, or Arg to Leu substitution. Heterozygosity for the Bbeta 14 Arg --> Cys mutation was verified by PCR amplification and DNA sequence analysis.

Topics: Adult; Amino Acid Substitution; Arginine; Catalysis; Cysteine; Family Health; Female; Fibrin; Fibrinogen; Fibrinopeptide A; Fibrinopeptide B; Glycoproteins; Heterozygote; Humans; Mass Spectrometry; Molecular Weight; Mutation; Point Mutation; Polymerase Chain Reaction; Sequence Analysis; Thrombin; Thrombosis

Using two-dimensional echocardiography, we studied the pathophysiology of intracardiac thrombus regression accompanied by anticoagulant therapy in 82 consecutive patients with acute cardiogenic cerebral embolism. We noted intracardiac thrombus in 15 patients; nine of the 15 were started on anticoagulant therapy with warfarin potassium to maintain the prothrombin time between 2.5 and 3.5 (international normalized ratio). Serial two-dimensional echocardiograms were obtained for these nine patients before and after anticoagulation, with the plasma levels of fibrinopeptide A, fibrinopeptide B beta 15-42, and D-dimer measured at the same time. In eight of the nine patients the intracardiac thrombi gradually decreased in size while the plasma level of fibrinopeptide A fell to within the normal range and the plasma levels of fibrinopeptide B beta 15-42 and D-dimer remained above the normal ranges. In the other patient the thrombus disappeared, with embolization to the right arm immediately after starting anticoagulant therapy. Mobile or small thrombi regressed earlier than nonmobile or large ones. We conclude that regression of intracardiac thrombi after anticoagulation may be based on the relative predominance of plasma fibrinolytic activity over anticoagulation-inhibited thrombin activity.

Topics: Aged; Anticoagulants; Echocardiography; Female; Fibrin Fibrinogen Degradation Products; Fibrinopeptide A; Fibrinopeptide B; Heart Diseases; Humans; Intracranial Embolism and Thrombosis; Male; Middle Aged; Prothrombin Time; Thrombosis

Topics: Amino Acid Sequence; Disseminated Intravascular Coagulation; Fibrin Fibrinogen Degradation Products; Fibrinogen; Fibrinopeptide A; Fibrinopeptide B; Humans; Immunoassay; Molecular Sequence Data; Peptide Fragments; Reference Values; Thrombosis

Arterial thrombi and atherosclerotic lesions were analyzed immunochemically and examined histologically. The extent of in vivo proteolytic cleavage of the amino-terminal end of fibrinogen by thrombin and plasmin was determined and quantitated by specific radioimmunoassays. The samples were treated with cyanogen bromide (CNBr), and the total amount of fibrinogen and fibrin-derived protein was determined as NDSK, the NH2-terminal disulfide knot of fibrinogen. Thrombin-releasable fibrinopeptides A and B were used to quantitate fibrinogen and fibrin I. Previous plasmin cleavage of the B beta chain was inferred from the amount of B beta 1-42 and B beta 15-42 in undigested NDSK. The results obtained in both acute and organized thrombi indicate that approximately 60% of the total protein (as determined by amino acid analysis) was fibrinogen-derived and that 70% to 80% of the fibrinogen-derived material was fibrin II. These findings support the hypothesis that fibrin II as distinct from fibrin I is the predominant component in a thrombus. In samples from normal and atherosclerotic aortas, fibrinogen-derived protein comprised less than 10% of the total protein. Samples from grossly normal aortas contained only fibrinogen and fibrin I. Fibrinogen concentration decreased and fibrin II concentration increased with increasing severity of the lesions, suggesting that increased fibrin II formation is associated with progression of atheromas.

Topics: Aorta; Arteriosclerosis; Fibrin; Fibrinogen; Fibrinolysin; Fibrinopeptide A; Fibrinopeptide B; Humans; Thrombin; Thrombosis

A congenitally abnormal fibrinogen was isolated from blood of a young man with deep-vein thrombosis. Two other affected members of his family had three episodes of severe arterial thrombosis. The fibrinogen showed a delayed clotting by thrombin, but a normal clotting by Arvin, Reptilase, and prothrombin-staphylocoagulase complex. Analysis of the fibrinopeptides A and B by High Performance Liquid Chromatography did not reveal an abnormal peptide structure. The rate of release of A and B peptides by thrombin was strongly delayed, whereas the rate of release of fibrinopeptide A by Arvin appeared to be normal. The fibrin polymerization rate was normal. Interactions between the abnormal fibrinogen, platelets and the fibrinolytic system were also normal. Evidence is presented that the defective interaction between fibrinogen Milano II and thrombin is associated with a defective binding of thrombin to the fibrin moiety of the abnormal fibrinogen.

Topics: Adult; Blood Coagulation Disorders; Fibrin; Fibrinogen; Fibrinogens, Abnormal; Fibrinopeptide A; Fibrinopeptide B; Humans; Male; Pedigree; Platelet Aggregation; Thrombin; Thrombophlebitis; Thrombosis

Fibrinogen New York 1 (NY-1) was identified in a family with a thrombotic tendency. Studies on fibrinogen NY-1 and the fibrinogen from her brother, designated NY-1a, showed that both have abnormal thrombin-nonclottable fibrinogen (50% of the total fibrinogen in NY-1 and 35-40% in NY-1a) and that the trait is heterozygous and autosomal codominant. The abnormal fibrinogen polymerizes in the presence of calcium and can be further cross-linked by Factor XIIIa. The release rates of fibrinopeptides A and B by thrombin from both (NY-1 and NY-1a) were slower than those from normal fibrinogen. Two mol of fibrinopeptide A but only 0.6-1.0 (NY-1) or 1.0-1.3 (NY-1a) mol of fibrinopeptide B were released per mol of fibrinogen. Additionally, only 1.0 (NY-1) or 1.3 (NY-1a) mol of the B beta(1-42) peptide were released by plasmin/mol. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the reduced fibrinogen revealed two protein bands in the B beta-chain region (Mr = 54,000 as compared with 57,300 for the normal). When NY-1a fibrinogen was treated with CNBr, two sizes of the NH2-terminal disulfide knot were obtained (Mr = 59,000 and 49,000). The Mr = 49,000 component is consistent with an abnormal NH2-terminal disulfide knot with two defective NH2-terminal B beta-chains. Amino acid sequence analyses demonstrated that the abnormal B beta-chain is the result of a deletion in the sequence from residues 9 to 72. This deletion corresponds exactly to exon 2 of the gene. Since this family has a thrombotic tendency, the defect in the fibrinogen may be important in the pathogenesis of thrombosis in this family.

Topics: Amino Acid Sequence; Base Sequence; Cyanogen Bromide; DNA; Electrophoresis, Polyacrylamide Gel; Fibrinogen; Fibrinogens, Abnormal; Fibrinolysin; Fibrinopeptide A; Fibrinopeptide B; Humans; Molecular Weight; Pedigree; Thrombosis

We have studied the effects of urokinase (UK) on concentration changes of alpha 2 antiplasmin (alpha 2 AP) and on fibrino(geno)lysis. Medium dose (480,000 u) or large dose (960,000 u) of UK was given to each of seven normal volunteers by intravenous drip infusion within six hours, and then blood and urine analyses were carried out. Total alpha 2 AP, which includes free alpha 2 AP and alpha 2 AP-plasmin complex, decreased to about 50% of the original value with large dose of UK. alpha 2 AP-plasmin complex appeared in the plasma one hr after UK infusion and increased up to 50% of total alpha 2 AP at the end of UK infusion. B beta peptides, which are liberated from fibrin(ogen) at the very early stage of fibrino(geno)lysis, increased significantly with UK infusion, and was 65 times as much as the normal range at the end of UK infusion. Urinary B beta peptides increased as well as plasma B beta peptides. On the other hand, fibrin(ogen) degradation products (FDP) measured with enzyme immunoassay (EIA) increased only slightly, and moreover, urinary FDP was not detectable at any time. Plasma fibrinogen levels did not decrease and changed within the normal range in both groups. We then gave 960,000 u of UK to four patients with deep vein thrombosis and blood analyses were carried out as with normal volunteers. The most significant observation different from that of normal volunteers was shown in FDP levels. Serum FDP levels of four patients increased significantly in comparison with normal volunteers. Urinary FDP increased as significantly as plasma FDP. In conclusion, the infusion of 960,000 u of UK caused only very early stage of fibrinogenolysis without advanced fibrinogenolysis in normal volunteers, but in thrombotic patients, advanced fibrinolysis was observed.

Topics: alpha-2-Antiplasmin; Fibrinogen; Fibrinolysin; Fibrinolysis; Fibrinopeptide B; Humans; Plasminogen; Protease Inhibitors; Thrombosis; Urokinase-Type Plasminogen Activator

Topics: Disseminated Intravascular Coagulation; Electrophoresis, Polyacrylamide Gel; Fibrin; Fibrin Fibrinogen Degradation Products; Fibrinopeptide A; Fibrinopeptide B; Hemorrhage; Humans; Models, Chemical; Molecular Weight; Thrombosis

Topics: Animals; Anticoagulants; Disseminated Intravascular Coagulation; Dogs; Epitopes; Fibrinogen; Fibrinopeptide A; Fibrinopeptide B; Heparin; Humans; Radioimmunoassay; Thrombin; Thromboembolism; Thrombosis