Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.5 (thrombin)
33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Plasma exchange has been proposed as a treatment for multiple disorders. Three patients with amyotropic lateral sclerosis, who were hemostatically normal, were studied through a total of 11 4-liter exchanges. Plasma was replaced by an equal volume of 5% albumin or 5% plasma protein fraction. Serial studies revealed that immediately after the exchange transfusion, there was significant prolongation of the prothrombin, partial thromboplastin, and thrombin times with reduction of the fibrinogen and antithrombin III levels. Factors V, VII-X, IX, and X were all significantly decreased, as were the factor VIII antigen, procoagulant, and the ristocetin cofactor activities. Platelet counts were obtained before and after exchanges and revealed significant decreases. Four hours after exchange, all parameters remained abnormal except the factor IX, ristocetin cofactor, and factor VIII procoagulant activities. By 24 hr, all hemostatic parameters had returned to normal. These studies indicate that plasma-exchange transfusion with material devoid of coagulation factors results in a coagulation defect that may be of clinical significance in a hemostatically compromised patient.
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PMID:The hemostatic imbalance of plasma-exchange transfusion. 46 36

To clarify the action of dextran sulphate, a heparin analogue, in the clotting of fibrinogen by thrombin, determinations were carried out on the clotting activity, the release of fibrinopeptides from fibrinogen, and the hydrolytic activity of thrombin against a peptide chromogenic substrate in the absence or presence of antithrombin III (heparin cofactor). It was shown that dextran sulphate itself inhibited thrombin activity, and its inhibition was dependent on the molecular weight and the sulphur content of the dextran sulphate. Although heparin markedly enhanced the antithrombin activity of antithrombin III, dextran sulphate did not activate antithrombin III.
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PMID:Effect of dextran sulphates on thrombin activity. 46 1

Thrombocytin, a serine protease from Bothrops atrox venom, caused platelet aggregation and release of platelet constituents at a concentration of 10(-7) M and clot retraction at a concentration of 2 x 10(-9) M. Thrombocytin was slightly more active when tested on platelets in plasma than on washed platelets suspended in Tyrode--albumin solution. Thrombin was 5 times more active than thrombocytin when tested on platelets in plasma and 50 times more active when tested on washed platelets. The patterns or release induced by thrombocytin and thrombin were similar. Prostaglandin E1 (10(-5) M) produced complete inhibition of platelet release induced by thrombocytin and thrombin. Indomethacin (10(-4) M) was without any effect. Antithrombin III, in the presence of heparin, inhibited the action of thrombocytin on platelets and on a synthetic peptide substrate (Tos-Gly-Pro-Arg-pNA.HCl). formation of an antithrombin III--thrombocytin complex was demonstrated on NaDodSO4--polyacrylamide gel electrophoresis. Hirudin and alpha 1-antitrypsin did not inactivate thrombocytin. Thrombocytin had a low fibrinogen-clotting activity (less than 0.06% that of thrombin). Thrombocytin also caused progressive degradation of the alpha chain of human fibrinogen, and it cleaved prothrombin, releasing products similar to intermediate 1 and fragment 1 produced by thrombin. Thrombocytin activated factor XIII by limited proteolysis and increased the procoagulant activity of factor VIII in a manner analogous to that of thrombin.
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PMID:Thrombocytin, a serine protease from Bothrops atrox venom. 2. Interaction with platelets and plasma-clotting factors. 47 69

The ability of heparin fractions of different molecular weight to potentiate the action of antithrombin III against the coagulation factors thrombin and Xa has been examined in purified reaction mixtures and in plasma. Residual thrombin and Xa have been determined by their peptidase activities against the synthetic peptide substrates H-D-Phe-Pip-Arg-pNA and Bz-Ile-Gly-Arg-pNA. High molecular weight heparin fractions were found to have higher anticoagulant activities than low molecular weight heparin when studied with both thrombin and Xa incubation mixtures in purified mixtures and in plasma. The inhibition of thrombin by heparin fractions and antithrombin III was unaffected by other plasma components. However, normal human plasma contained a component that inhibited the heparin and antithrombin III inhibition of Xa particularly when the high molecular weight heparin fraction was used. Experiments using a purified preparation of platelet factor 4 suggested that the platelet-derived heparin-neutralizing protein was not responsible for the inhibition.
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PMID:Evidence for a plasma inhibitor of the heparin accelerated inhibition of factor Xa by antithrombin III. 47 56

Blanket serial controls are not necessary in low-dosage heparin treatment. It would, in any case, be difficult under normal clinical conditions and would run counter to the whole conception of low-dose heparin treatment. However, in problem cases with an increased thrombo-embolic risk, sensitive methods for monitoring the heparin effect are recommended. A study on 150 patients has indicated that the most sensitive method is the use of chromogenic substrates. Thrombin time, using low-concentration thrombin solution of 1.5 NIH units/ml, thrombelastogram and activated partial thromboplastin time are less sensitive. Antithrombin III levels should be determined in all cases of increased heparin tolerance. With reduced antithrombin III levels and higher body weight an increase of the standard dose from 5000 U.S.P. units heparin t. i. d. subcutaneously to 7500 U.S.P. units t. i. d. should be considered.
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PMID:[Does low-dosage heparin treatment require serial haematological controls? (author's transl)]. 47 60

Coagulation studies using conventional methods and chromogenic substrates were performed on umbilical arterial and venous blood from 33 newborns after delivery. In the arterial samples, thrombin time (TT) was significantly prolonged and the activities of factors I, II, V and VII, as well as the inhibitors heparin, antithrombin III and antiplasmin, were significantly decreased. This could probably be explained by a mild form of disseminated intravascular coagulation (DIC) occurring in the baby during delivery.
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PMID:Coagulation studies on umbilical arterial and venous blood from normal newborn babies. 47 78

The precise quantitation of activated factors in human factor IX concentrates has been accomplished with the use of recently developed, specific assays for factors IXa, Xa, and thrombin. The assay for factor IXa, which measures the initial rate of 3H-factor-X activation, was shown to be specific for factor IXa in the concentrates. Activated factor IX concentrates contained 1.0-2.3 microgram/ml of factor IXa; whereas the assays of unactivated concentrates were negative (less than 0.2 microgram/ml). The assays of factor Xa and thrombin, which measure the initial rate of p-nitroaniline release from S-2222 and S-2238, respectively, showed similar small amounts of factor Xa (4-34 ng/ml) and thrombin (12-76 ng/ml) in the activated and unactivated concentrates. The nonactivated partial thromboplastin time of the concentrates correlated significantly with the factor IXa content, but not with factor Xa or thrombin. Antithrombin III antigen in 3 of 4 concentrates was several-fold higher than antithrombin III activity, suggesting the presence of antithrombin III complexed with activated factors. These results support the hypothesis that the degree of activation of factor IX concentrates is related primarily to the concentration of factor IXa, which may be responsible for the thrombogenicity of these concentrates in some clinical settings.
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PMID:Activated clotting factors in factor IX concentrates. 49 95

Fourteen patients with a documented sudden neurosensory hearing loss and four patients with other diseases causing neurosensory hearing loss were studied. The standardized coagulation workup included hematocrit, activated partial thromboplastin generation time, thrombin generation, prothrombin time, phase platelet count, platelet adhesivity, protamine sulfate, serum antithrombin III activity, fibrinogen, and Factor VIII values. Ony those patients having documented evidence of a neurosensory hearing loss occurring within hours or days were included in this study. Eight of the 14 paitents with a documented sudden neurosensory hearing loss satisfied our laboratory criteria for a diagnosis of in vitro hypercoagulability. Three of these patients had abnormal thrombin generation values, 4 had abnormal serum antithrombin III values, and 1 had an elevated platelet count. Four other patients with other diseases causing neurosensory hearing loss did not show evidence of in vitro hypercoagulability. It would appear from this data that coagulation abnormalities play a role in the pathogenesis of sudden neurosensory hearing loss.
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PMID:Hypercoagulability as a cause of sudden neurosensory hearing loss. 50

Guinea pig antithrombin III has been purified from plasma by sequential heparin-Sepharose affinity chromatography, DE-52 cellulose chromatography, isoelectric focussing, and Sephadex G-100 gel filtration chromatography. The final product was homogeneous as judged by sodium dodecyl sulfate disc gel electrophoresis. Purification was 202-fold with a yield of 41%. Antiproteinase activity of antithrombin III was determined by progressive inactivation of thrombin coagulant and amidolytic activity. Heparin cofactor activity was demonstrated by immediate inactivation of thrombin by antithrombin III in the presence of minute quantities of heparin. It also could be demonstrated that thrombin inactivation by antithrombin III occurs by formation of a bimolecular complex whose rate of formation is markedly enhanced by minute quantities of heparin.
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PMID:Purification and properties of guinea pig antithrombin III. 50 72

The saliva of the tsetse, Glossina morsitans morsitans Westwood, has antithrombin anticoagulant activity and inhibits thrombin's esterolytic activity. It has no other detectable anticoagulant properties. The anticoagulant elutes in a single peak on Sephadex fraction, is immediately acting, heat and storage stable, and has a molecular weight of 11-13,000. Unlike heparin it is not neutralized by protamine sulphate or toluidine blue and does not require the co-factor, antithrombin III, for optimal anticoagulant activity. It has similar properties to hirudin, but does not elute with a protein peak upon Sephadex fractionation and has a slightly different molecular weight. Salivary gland homogenates contained neither a plasminogen activator nor fibrinolytic activity. The sera of rabbits used to maintain tsetses, which contained precipitating antibodies against saliva, did not neutralize the salivary anticoagulant in vitro. The properties of this anticoagulant suggest that it might be a potentially useful antithrombotic agent in man.
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PMID:Effects of tsetse (Glossina morsitans morsitans Westw.) (Diptera: Glossinidae) salivary gland homogenate on coagulation and fibrinolysis. 50 76


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