scholarly journals THROMBIN FORMATION. II. EFFECTS OF LYSIN (FIBRINOLYSIN, PLASMIN) ON PROTHROMBIN, AC-GLOBULIN AND TISSUE THROMBOPLASTIN. 1

1949 ◽  
Vol 28 (6 Pt 2) ◽  
pp. 1507-1510 ◽  
Author(s):  
Jessica H. Lewis ◽  
Ann C. Howe ◽  
J. H. Ferguson
Keyword(s):  
Tissue Thromboplastin ◽  
Thrombin Formation

scholarly journals Experimental Studies on Factor VIII Inhibitor Bypassing Activity

1977 ◽  
Author(s):  
H. Vinazzer
Keyword(s):  
Factor Viii ◽  
Calcium Chloride ◽  
Experimental Studies ◽  
Factor Xa ◽  
Factor Viii Inhibitor ◽  
Factor V ◽  
Factor X ◽  
Tissue Thromboplastin ◽  
Viii Inhibitor ◽  
Thrombin Formation

The exact action of factor VIII inhibitor bypassing activity (FEIBA) is still unclear. For this reason, a series of experimental studies was carried out. Procoagulant activities were examined by standard one-stage methods while factor Xa and thrombin were measured by chromogenic substrates. Activities of factors II, VII, IX, and X were similar to PPSB fractions. In addition, low factor V activity and a phospholipid were detected. No activated factor X was present in FEIBA but there was a trace amount of 2.1 NIH units of thrombin per 100 FEIBA units. On addition of calcium chloride slow thrombin formation could be observed which however, reached 1100 NIH units of thrombin per 100 FEIBA units within an incubation time of 10 min. The velocity of thrombin formation was greatly enhanced by addition of a PTT reagent and of thromboplastin respectively. Factor Xa on the other hand, was neither formed after addition of calcium chloride nor by a PTT reagent. Tissue thromboplastin however, activated Xa from FEIBA in the same manner as a PTT reagent plus barium sulfate plasma. From these results, the conclusion could be drawn that thrombin could readily be made available from FEIBA while activation of Xa either needed the complete endogenous pathway or the presence of tissue thromboplastin. The procoagulant activity of FEIBA therefore, could be attributed to direct thrombin formation. By this process, an activation of the clotting mechanism in plasmas deficient in endogenous coagulation factors, and a complete independence from the presence or absence of a specific antibody could be explained.

Fibrinopeptide A Cleavage And Platelet Release In Whole Blood In Vitro

1981 ◽  
Author(s):  
K L Kaplan
Keyword(s):  
Platelet Rich Plasma ◽  
Blood Platelet ◽  
Fibrinopeptide A ◽  
Platelet Factor ◽  
Platelet Surface ◽  
Tissue Thromboplastin ◽  
Platelet Release ◽  
The Relationship ◽  
Thrombin Formation

The relationship between platelet release and fibrinopeptide A (FPA) cleavage from fibrinogen to form fibrin I was examined in blood allowed to clot in vitro. FPA and the platelet release products (platelet factor 4 and (β-thrombo- globulin) were quantitated by radioimmunoassay. In undisturbed blood platelet release and FPA cleavage occurred simultaneously. Addition of hirudin prevented platelet release as well as FPA cleavage, indicating that thrombin was essential for platelet release. Addition of collagen increased platelet release and then FPA cleavage, and addition of ADP had a similar but less marked effect, suggesting that increased platelet activation accelerated thrombin formation. PGE1 and theophylline inhibited platelet release but did not affect FPA cleavage in the initial stages of incubation. When blood was agitated, the effects of collagen and PGE1 and theophylline were qualitatively similar to those in undisturbed blood, but addition of hirudin no longer affected platelet release, suggesting that in this case platelet release occurred independently of thrombin action. Addition of dilute thrombin or tissue thromboplastin to undisturbed blood accelerated FPA cleavage with little effect on platelet release, indicating that exogenous thrombin or thrombin generated by the extrinsic system behaves differently from that generated by the intrinsic system. Finally, thrombin concentrations were compared in platelet rich and platelet free plasma and were found to be increased in platelet rich plasma in spontaneously clotting blood but not in blood to which tissue thromboplastin was added. These relationships suggest that thrombin formation via the intrinsic system occurs on the platelet surface leading to simultaneous platelet release and FPA cleavage, while thrombin generated via tissue thromboplastin leads to thrombin formation in the plasma and FPA cleavage precedes platelet release. Collagen primarily accelerates platelet release and secondarily increases thrombin formation.

Effects of Radiographic Contrast Agents on Thrombin Formation and Activity

1998 ◽  
Vol 80 (08) ◽  
pp. 266-272 ◽  
Author(s):  
Andrew Parker ◽  
William Fay
Keyword(s):  
Contrast Agents ◽  
Tissue Factor ◽  
Coronary Angioplasty ◽  
Molecular Mechanisms ◽  
Factor Viia ◽  
Minor Effect ◽  
Ionic Contrast ◽  
Radiographic Contrast ◽  
Inhibition Of Thrombin ◽  
Thrombin Formation

SummaryClinical trials suggest that the risk of thrombosis during coronary angioplasty is lower with ionic contrast agents than with nonionic contrast agents. However, the molecular mechanisms underlying this effect are unknown. This study examined the effects of contrast agents on thrombin formation and its interaction with substrates, inhibitors, and ligands to define potential mechanisms by which contrast agents affect thrombus formation. Two ionic agents, diatrizoate and ioxaglate, and one nonionic agent, ioversol, were studied. Ionic agents inhibited factor X activation by the tissue factor-factor VIIa complex more potently than ioversol (53 ± 3.7, 43.0 ± 1.9, and 26.5 ± 2.4% inhibition by diatrizoate, ioxaglate, and ioversol, respectively, at concentrations of 5%). Ionic contrast agents were potent inhibitors of prothrombinase function, inhibiting thrombin formation by >75% at contrast concentrations of 0.6% (p <0.005). Ioversol inhibited prothrombinase to a significantly lesser extent than ionic agents. Clotting assays suggested that ioxaglate was the most potent inhibitor of thrombin generation in plasma despite having the least effect on fibrin polymerization. Contrast agents inhibited binding of thrombin to fibrin, with ionic agents producing a more potent effect than ioversol (p <0.02). However, contrast agents did not inhibit thrombin-mediated platelet activation, had only a minor effect on inhibition of thrombin by antithrombin III, and did not affect thrombin-hirudin interactions. In summary, these studies identify specific mechanisms by which radiographic contrast agents inhibit thrombin formation and function – i.e. inhibition of tissue factor-dependent factor Xa generation, inhibition of the prothrombinase complex, and inhibition of thrombin binding to fibrin. These findings may help to explain the reduced risk of thrombosis during coronary angioplasty associated with ionic contrast agents.

Relative Sensitivity of Different Tests in the Detection of Low Titer Lupus Anticoagulants

1988 ◽  
Vol 60 (02) ◽  
pp. 217-219 ◽  
Author(s):  
B Lesperance ◽  
M David ◽  
J Rauch ◽  
C Infante-Rivard ◽  
G E Rivard
Keyword(s):  
Relative Sensitivity ◽  
Fetal Outcome ◽  
Anticardiolipin Antibodies ◽  
Lupus Anticoagulants ◽  
Normal Plasma ◽  
Coagulation Tests ◽  
High Dilutions ◽  
Tissue Thromboplastin ◽  
High Concentrations ◽  
Kaolin Clotting Time

SummaryLupus anticoagulants (LA) and anticardiolipin antibodies have been strongly associated with recurrent abortion and fetal death. Because steroids have been reported to improve the fetal outcome of LA associated pregnancies, presumably by decreasing the levels of LA, it becomes desirable to have a simple and reliable test to monitor the levels of the putative antibody. To this effect, we assessed the capacity of the following coagulation tests to detect the presence of LA in serial dilutions of patient plasma with pooled normal plasma: kaolin clotting time (KCT), tissue thromboplastin inhibition test (TTIT), dilute Russell Viper venom time (DRVVT) and activated partial thromboplastin time with standard and high concentrations of phospholipids (SC and HCAPTT). All samples were also evaluated for the presence of anticardiolipin antibodies with an ELISA. The KCT was able to detect LA at a much greater dilution in normal plasma than any of the other clotting assays. The ELISA was comparable to KCT in its ability to detect high dilutions of LA.

The Activation of Human Factor IX

1975 ◽  
Vol 33 (03) ◽  
pp. 553-563 ◽  
Author(s):  
B Østerud ◽  
K Laake ◽  
H Prydz
Keyword(s):  
Molecular Weight ◽  
Sodium Dodecyl ◽  
Apparent Molecular Weight ◽  
Factor Ix ◽  
Factor Vii ◽  
Activate Factor ◽  
Human Factor Ix ◽  
Factor Xia ◽  
Tissue Thromboplastin ◽  
Native Factor

SummaryThe activation of factor IX purified from human plasma has been studied. Factor XIa and kallikrein separately activated factor IX to factor IXa. In both cases factor IX a had an apparent molecular weight of about 42–45000 in sodium dodecyl sul-phate-polyacrylamide disc gel electrophoresis compared with a molecular weight of about 70000 for the native factor IX. The activation by XIa required Ca2+-ions whereas Ca2+-ions did not influence the activation by kallikrein. A mixture of tissue thromboplastin and factor VII or RusselPs-viper venom alone did not activate factor IX. Trypsin activated and plasmin inactivated factor IX.

Ultrastructural Changes of the Tissue Thromboplastin after Intravenous Injection in Rabbits

1978 ◽  
Vol 39 (01) ◽  
pp. 201-209 ◽  
Author(s):  
Hiroshi Hasegawa ◽  
Hiroshi Nagata ◽  
Makoto Murao
Keyword(s):  
Intravenous Injection ◽  
Vascular Endothelium ◽  
Model Experiment ◽  
Venous Return ◽  
Ultrastructural Changes ◽  
Membrane Structures ◽  
Tissue Thromboplastin ◽  
Short Time ◽  
Sheet Membrane

SummaryAttempts were made to demonstrate ultrastructural changes of the tissue thromboplastin after intravenous injection, as a model experiment on the pulmonary microthrombi formation induced by the tissue thromboplastin circulating from venous return.Concentrically arranged membrane structures of the injected thromboplastin disappeared in extremely short time after the injection of the thromboplastin in rabbits. The long sheet membrane of the injected thromboplastin was frequently seen as adhered to the vascular endothelium or to the surface of blood corpuscles. Furthermore, fibrin fibres were formed in contact with the long sheet membrane of the thromboplastin. Membrane structures were not found anywhere in the control rabbits.

On the Preparation of Bovine α-Thrombin

1978 ◽  
Vol 39 (01) ◽  
pp. 193-200 ◽  
Author(s):  
Erwin F Workman ◽  
Roger L Lundblad
Keyword(s):  
Immobilized Enzyme ◽  
Catalytic Properties ◽  
Specific Activity ◽  
Guanidine Hydrochloride ◽  
Low Molecular Weight ◽  
Reversible Process ◽  
Gel Beads ◽  
Tissue Thromboplastin ◽  
C 50 ◽  
Hydrolysis Of

SummaryAn improved method for the preparation of bovine α-thrombin is described. The procedure involves the activation of partially purified prothrombin with tissue thromboplastin followed by chromatography on Sulfopropyl-Sephadex C-50. The purified enzyme is homogeneous on polyacrylamide discontinuous gel electrophoresis and has a specific activity toward fibrinogen of 2,200–2,700 N.I.H. U/mg. Its stability on storage in liquid media is dependent on both ionic strenght and temperature. Increasing ionic strength and decreasing temperature result in optimal stability. The denaturation of α-thrombin by guanidine hydrochloride was found to be a partially reversible process with the renatured species possessing properties similar to “aged” thrombin. In addition, the catalytic properties of a-thrombin covalently attached to agarose gel beads were also examined. The activity of the immobilized enzyme toward fibrinogen was affected to a much greater extent than was the hydrolysis of low molecular weight, synthetic substrates.

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