Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Twenty-nine patients received intracoronary thrombolytic therapy for acute myocardial infarction 3.5 +/- 1.4 hours (mean +/- standard deviation) after the onset of pain. Ten patients received urokinase (UK) and 19 patients received streptokinase (SK). Laboratory variables of the coagulation system were measured before and immediately after therapy. When comparing patients in whom coronary artery recanalization occurred vs those in whom the artery remained occluded, those in whom recanalization was achieved had greater alterations in fibrinogen, prothrombin time, activated partial thromboplastin time, fibrin/fibrinogen degradation products and plasminogen by thrombolytic therapy than did those in whom recanalization was not achieved (p less than 0.05 for all variables). Euglobulin lysis time showed a similar but nonsignificant trend (p = 0.114). Patients who received SK showed markedly greater alterations in coagulation parameters than did patients treated with UK (p less than 0.05 for 5 of 6 variables measured) and had a much higher incidence of successful thrombolysis (74% for SK, 20% for UK). These data indicate that the development of a systemic fibrinolytic state contributes to success when using intracoronary thrombolytic agents in acute myocardial infarction. Rather than being considered an adverse effect of therapy, a systemic lytic state may serve as a reasonable clinical goal in attempting to produce thrombolysis.
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PMID:Relation of effectiveness of intracoronary thrombolysis in acute myocardial infarction to systemic thrombolytic state. 403 24

A model was experimentally made with 2 hours serial infusion of thromboplastin (Tp) into rabbits to examine the drug's effect on a hemorrhagic tendency and to elucidate the coagulation and fibrinolytic system in acute DIC encountered in obstetrics, and the system was periodically observed. Groups given the drug, given it during pregnancy, those which bled massively, and those with accelerated fibrinolysis were prepared. The results are as follows. 1) Fibrinogen, PT, APTT, TEG, ELT, AT-III, antiplasmin activity, and platelet count varied markedly from the initiation of Tp injection, and returned to normal following termination. 2) Blood from the heparin dose group showed non-coagulation but decreases in the platelet count and fibrinogen were inhibited. 3) In the aprotinin dose group, serial 2 hour administration induced inhibition of fibrinolysis despite the relatively delayed appearance of anti-fibrinolytic activity. 4) No fibrinolytic effects were seen in anti-plasmin activity or ELT in the tranexamic acid dose group. 5) Lowering of parameters examined was marked in the Tp dose group during pregnancy. 6) The mortality rate up to 6 hours after Tp infusion was 54.5% with solely given, and 10% with group given drug. 7) Death within one hour of Tp infusion in the mass bleeding group, being rated for 50%, was improved to 16.7% by the pre-administration of urokinase.
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PMID:[Treatment of obstetrical disseminated intravascular coagulation--sequential changes of coagulation and fibrinolytic system in DIC rabbits]. 618 25

A new affinity chromatographic procedure was devised to purify inactive renin by using a selective hydrophobic interaction of inactive renin to octyl-Sepharose. Additional extensive purification was accomplished by immunoaffinity chromatography on antihuman renin immunoglobulin G-Sepharose. A trace amount of active renin was removed by chromatography on pepstatin-Sepharose. Human plasma inactive renin purified by this method was free from protease inhibitors and permitted the investigation of protease-mediated activation without the acid treatment which was used previously to remove inhibitors. Human plasma kallikrein, human plasmin, cathepsin B1, and arginine esteropeptidases associated with mouse epidermis growth factor and nerve growth factor were effective activators. Human urinary kallikrein, hog pancreatic kallikrein, and rat urinary esterase A were inefficient activators of low potency. Thrombin, factor Xa, factor XIIa, and urokinase did not activate inactive renin. The in vitro activation of 56,000-dalton inactive renin by these proteases was not accompanied by a recognizable reduction in molecular weight. Activation required plasma albumin, presumably as a protecting substance. These results suggest that human inactive renin can be activated by a minimum change in its molecular size.
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PMID:Human plasma inactive renin: purification and activation by proteases. 621 31

The function of fibrinolysis is to dissolve fibrin clots. The agent of fibrinolysis is plasmin, a glycoprotein with gram molecular weight (GMW) of 90,000. Under natural conditions, plasminogen is converted to plasmin by tissue plasminogen activator (TPA). Activation occurs on the fibrin surface, thus confining proteolytic activity to the appropriate site. Tissue plasminogen activator, produced by monoclonal methods, has recently been made available for limited therapeutic use. Currently streptokinase and urokinase are widely used therapeutically to activate plasminogen. These agents cause plasmin to be formed which is free in the circulation as well as bound to fibrin, resulting in proteolysis of circulating plasminogen and clotting factors. Fibrinolytic therapy has proven to be more beneficial than anticoagulation alone for deep vein thrombi and for pulmonary emboli. During therapy, laboratory studies demonstrate reduced concentrations of plasminogen, fibrinogen, and of alpha-2 plasmin inhibitor, and prolongation of activated partial thromboplastin time and thrombin time. Laboratory findings must be correlated with the clinical course. Demonstration of circulating plasmin-antiplasmin complex may be a useful indicator of active fibrinolysis.
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PMID:Fibrinolysis--a review. 623 87

Protein C inhibitor isolated from human plasma inhibited thrombin, factor Xa, trypsin and chymotrypsin as well as activated protein C, but had very little effect on urokinase and plasmin. The inhibition constants (K1) of protein C inhibitor for activated protein C, thrombin and factor Xa were 5.6 X 10(-8) M, 6.7 X 10(-8) M and 3.1 X 10(-7) M, respectively. The second-order rate constant for inhibition of activated protein C by the inhibitor increased about 30-fold in the presence of an optimal heparin concentration (5-10 units/ml). The inhibition of activated protein C by plasma protein C inhibitor was also accelerated by heparin. When activated protein C (Mr = 62,000) was incubated with protein C inhibitor (Mr = 57,000), enzyme-inhibitor complexes with apparent Mr = 102,000 and 88,000 were observed in the nonreduced and the reduced samples, respectively, on SDS-polyacrylamide gel electrophoresis. In addition to these complexes, a band of unbound enzyme and a band with Mr = 54,000 were detected. When 125I-labeled protein C inhibitor was exposed to activated protein C, the inhibitor band was converted to bands with apparent Mr = 102,000 and 54,000 in the nonreduced samples, as determined by autoradiography after gel electrophoresis in SDS. The band with Mr = 54,000 also appeared when the inhibitor reacted with other serine proteases. The activated protein C was released from the inactive complex by treatment with 1 M ammonia or hydroxylamine. This phenomenon was found by SDS-polyacrylamide gel electrophoresis to represent the dissociation of the enzyme-inhibitor complex by ammonia or hydroxylamine into the free enzyme and the proteolytically modified inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanism of inhibition of activated protein C by protein C inhibitor. 632 92

Since the introduction of synthetic chromogenic and fluorogenic peptide substrates from serine proteases, the testing of coagulation has undergone a dramatic conceptual and methodological change. The concept of coagulation profiling has emerged and automated methodologies are being introduced. Synthetic substrate methods for the evaluation of antithrombin-III; progressive antithrombin; plasminogen; antiplasmin; prekallikrein; antikallikrein ; alpha 1-antitrypsin; prothrombin; heparin; platelet factor IV; urokinase; tissue activator of plasminogen; factor assays; amidolytic equivalents of prothrombin time; and partial thromboplastin time have been developed. Studies on antithrombin-III indicate that immunological methods evaluate the total immunoreactive-antithrombin-III (antigenic) level and do not discriminate between functionally active forms and the AT-III serine protease complex. The clinical significance of AT-III measured by immunological methods is highly questionable. The coagulant assays for the measurement of AT-III require purified alpha-thrombin preparations. The noncoagulant forms of thrombin (beta- and gamma-) result in falsely low antithrombin-III quantitation. The molecular heterogeneity in a given thrombin preparation if standardized in terms of its amidolytic activity does not produce any errors in the quantitation of AT-III levels with synthetic peptide methods. None of the immunological methods provide clinically relevant information except in normal plasma where the immunological and functional activities are identical. Analysis of pathologic plasma samples using laser nephelometry, radial immunodiffusion and radioimmunoassay methods revealed that the functional activity of various serine protease inhibitors is greatly reduced but the reduction in the immunological quantities is minimal. Since coagulation proteins are functional, a ratio between their functional activity and absolute protein levels may be a useful parameter. Employing human and bovine thrombin; bovine and human Xa with their respective substrates, the absolute quantitation of heparin is satisfactorily carried out, however, these assays only measure heparin concentrations and do not reflect the overall anticoagulant effect of heparin. Using the synthetic substrates, the value of measuring absolute concentrations of heparin in a patient on heparin therapy is questionable. With the introduction of fluorogenic substrates, the presence of activated coagulation factors may be demonstrated in patients with thrombotic disorders.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Synthetic peptide substrates in hemostatic testing. 637 39

The steady-state kinetic parameters of the tripeptides D-Val-Leu-Lys-, Ala-Phe-Lys-, and < Glu-Phe-Lys- in which the free carboxyl group was substituted with p-nitroaniline (substrate) or chloromethane (inhibitor), towards the serine proteinases plasmin (EC 3.4.21.7), thrombin (EC 3.4.21.5), urokinase, factor Xa, and trypsin (EC 3.4.21.4) were investigated. The p-nitroanilide derives were found to be very good substrates for plasmin, 2.5--40-times less efficient towards trypsin and very poor (100--10 000-times less efficient) substrates for thrombin, factor Xa and urokinase. The chloromethyl ketone derivatives were comparably efficient inhibitors of plasmin and trypsin and in general very poor (100--10 000-times weaker) inhibitors of thrombin, factor Xa and urokinase. D-Val-Leu-Lys-pNA however was a very poor substrate but D-Val-Leu-Lys-CH2Cl a very efficient inhibitor for thrombin. The variability in susceptibility of the substrates towards the enzymes was due to differences in their Michaelis constant, in their deacylation rate constant or both. the variable efficiency of the inhibitors was mostly due to differences in their dissociation constant and much less to differences in their alkylation rate constant. Only a poor correlation (r = 0.25) was found between the efficiency of the p-nitroanilides as substrate and their homologous chloromethyl ketones as inhibitor. The most notable discrepancy was observed with the D-Val-Leu-Lys derivatives towards thrombin.
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PMID:Kinetic properties of tripeptide lysyl chloromethyl ketone and lysyl p-nitroanilide derivatives towards trypsin-like serine proteinases. 644 39

Inhibitory effects of FUT-175 (nafamstat mesilate) on coagulation, platelets and fibrinolysis were examined. FUT-175 prolonged activated partial thromboplastin time, thrombin time and prothrombin time in rabbit plasma. FUT-175 prolonged these coagulation times in human plasma at lower concentration than in rabbit plasma. FUT-175 inhibited platelet aggregation induced by a variety of aggregation agents in rabbit platelet-rich plasma (PRP). In human PRP, FUT-175 inhibited platelet aggregation induced by a variety of aggregation agents at lower concentration than in rabbit PRP. Lipopolysaccharide induced a dose-dependent platelet aggregation in dog PRP. FUT-175 showed an inhibitory effect on this aggregation. FUT-175 inhibited clot retraction in rabbit plasma. The fibrinolysis activity was measured on fibrinolysis of rabbit plasma activated by urokinase. FUT-175 prolonged this fibrinolysis time. Inhibitory effects on coagulation and fibrinolysis were also found ex vivo. FUT-175 prolonged bleeding time in mice. These results indicate that FUT-175 has potent inhibitory effects on coagulation, platelets and fibrinolysis.
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PMID:[Pharmacological studies of FUT-175, nafamstat mesilate. IV. Effects on coagulation, platelets and fibrinolysis]. 651 80

Activation of bovine plasma prekallikrein was investigated with several proteinases. Highly purified bovine plasma prekallikrein was rapidly activated to kallikrein [EC 3.4.21.8] by bovine activated Hageman factor, trypsin [EC 3.4.21.4] and Pronase P (proteinases from Streptomyces griseus) and more gradually by papain [EC 3.4.22.2] and ficin [EC 3.4.22.3]. Activation of prekallikrein was also observed with bovine plasmin [EC 3.4.21.7], but not with bovine clotting factors Xa (Stuart factor) [EC 3.4.21.6] and IXa (Christmas factor) or thrombin [EC 3.4.21.5]. Urokinase [EC 3.4.99.26], Reptilase, collagenase [EC 3.4.24.3], elastase [EC 3.4.21.11], alpha-chymotrypsin [EC 3.4.21.1], Nagarse [EC 3.4.21.14], and stem bromelain [EC 3.4.22 4] did not convert prekallikrein to kallikrein. Plasma kallikrein activated to Hageman factor released kinin rapidly from bovine high molecular weight (HMW) kininogen. However, from bovine low molecular weight (LMW) kininogen, liberation of kinin was extremely slow. The kallikrein activity was inhibited by soybean trypsin inhibitor (SBTI), Trasylol, diisopropylfluorophosphate (DFP), and N-alpha-tosyl-L-lysine chloromethylketone (TLCK), but not by egg-white trypsin inhibitor (EWTI), lima bean trypsin inhibitor (LBTI), heparin or hexadimethrine bromide (Polybrene). The kallikrein formed an enzyme-inhibitor complex with SBTI and Trasylol, but not with LBTI. Prekallikrein did not react with SBTI. Prekallikrein consists of a single polypeptide chain of molecular weight about 90,000, as estimated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Activation of prekallikrein by Hageman factor was found to involve cleavage of the single peptide bond on the disulfide-bridged polypeptide chain, and no change of molecular weight was observed during the activation. The peptide bond cleaved in prekallikrein by the activation was an Arg-X peptide bond on a disulfide-bridged polypeptide chain.
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PMID:Studies on prekallikrein of bovine plasma. II. Activation of prekallikrein with proteinases and properties of kallikrein activated by bovine Hageman factor. 676 24

Presence of chronic DIC (disseminated intravascular coagulation) eliciting an impeded blood coagulation has been postulated of late as one of the etiology causing toxemia of pregnancy, for which studies have been immunologically made. These theories remain unestablished. In this regard, the role of complement in blood coagulation has been noted, and their correlation is being elucidated. The author introduced a concept of complement to etiological theory of an impeded blood coagulation origin, by which toxemia of pregnancy was studied with emphasis placed on their correlation. The results obtained are as follow: 1) Thrombin and thromboplastin allowed in vitro to decreases the potency of complement, and the lowering also was seen even in the case of simultaneous supplement of urokinase and plasminogen. 2) The decrease also was periodically seen in rabbit's DIC experimentally made. 3) An increase in CH50, C3, C4, and factor B of normal pregnancy were of significance when compared with those of the control (p less than 0.001), while C1 inactivator decreased significantly (p less than 0.001). 4) CH50 was 52.2 +/- 2.4U/ml in severe toxemia, a decrease being of significance (p less than 0.01) as compared with that in third trimester of normal pregnancy. Those other parameters which tended to decrease included hemolytic activity of alternative pathway (AP-CH50), C4, and factor B except C1 inactivator with a trend being high.
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PMID:[Studies on relationship between complement and blood coagulation system in toxemia of pregnancy (author's transl)]. 706 48


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