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:3.4.21.6 (thromboplastin)
13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To probe the functional role of tryptophan 49 in human antithrombin III, a mutant antithrombin, W49K, has been expressed in baby hamster kidney cells. The mutation reduces the affinity for heparin pentasaccharide by 1.8 kcal mol-1 but does not alter the heparin enhancement of the rate of factor Xa inhibition. 1H NMR spectra of W49K antithrombin show that the structure of the protein and the mode of heparin binding appear to be unaltered by the mutation, although tryptophan 49 is perturbed by heparin binding. 19F NMR spectra of 6-fluorotryptophan-substituted antithrombin show that tryptophan 49 is in a solvent-exposed environment. The heparin-induced fluorescence enhancement of W49K antithrombin is significantly different from that of wild-type antithrombin. Pentasaccharide induces only a 24% enhancement of antithrombin fluorescence, while high affinity heparin induces an enhancement of 40%. The results indicate that tryptophan 49 is probably a heparin contact residue but can be mutated without altering the remaining heparin-antithrombin interactions or the heparin-induced conformational change and resultant activation toward Factor Xa. Hydrophobic as well as charge interactions are thus probably involved in the specificity of the antithrombin-heparin pentasaccharide interaction. The lower fluorescence enhancements suggest that the heparin-induced 40% fluorescence enhancement used as the hallmark of activating heparin species is not the best indicator of the structural change in antithrombin that results in enhancement of the rate of proteinase inhibition.
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PMID:Role of tryptophan 49 in the heparin cofactor activity of human antithrombin III. 140 May 4

Nonionic contrast media are suggested to cause increased thromboembolism (in vivo), because of less inhibitory action on blood coagulation and platelet aggregation (in vitro) as compared with ionic contrast media. Therefore, to prevent thrombotic complication, we examined whether differences in blood coagulation and fibrinolytic system between the two groups received nonionic (iopamidol) and ionic (ioxaglate) contrast media are seen in vivo when 2,500 unit heparin is administered during angiocardiography. 20 patients undergoing routine angiocardiography were randomized to two groups of 10 patients each. Blood heparin concentration, activated partial thromboplastin time, prothrombin time, thrombin-antithrombin III complex (TAT), antithrombin III, fibrinogen, alpha 2-plasmin inhibitor plasmin complex, fibrinogen and fibrin degradation product were measured at four stages during the procedure: before and 5 min after 2,500 unit bolus heparin administration, 5 min after left ventriculography, and at the end of procedure. Systemic heparinization inhibited clot formation in the presence of nonionic contrast media. TAT generations were elevated before heparinization, after heparinization, however these generations were remarkably inhibited in both groups. No remarkable differences were noted at 40 +/- 14 min duration of procedure when these parameters were compared between the two groups. Since nonionic contrast media did not activate blood coagulation and fibrinolytic system with 2,500 unit heparin administration as compared with ionic contrast media, systemic heparinization was demonstrated to be effective in the prevention of thrombotic complication.
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PMID:[Effects of contrast media under systemic heparinization on blood coagulation and fibrinolytic system during angiocardiography--comparison of ionic and nonionic contrast media]. 140 85

The decay rate of thrombin in plasma is shown to be linearly proportional to the concentration of antithrombin III (AT III), not only in the absence but also in the presence of heparin. This is a consequence of partitioning of heparin between AT III and other plasma proteins. In previous articles were calculated the prothrombin converting activity assuming a fixed concentration of AT III. Since AT III is consumed during the clotting process, prothrombinase activity is more accurately approximated using an algorithm that counts with the decrease of the AT III concentration. It is shown this leads to higher prothrombinase activities. The (absence of) inhibition of prothrombin conversion by prothrombinase in the presence of heparins found with the previous method is also found using the new algorithm. From the results presented it is evident that characteristic parameters of heparin action have to be normalised to the AT III concentration. On this basis we define a Standard Independent Unit of the antithrombin activity of heparin.
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PMID:The consumption of antithrombin III during coagulation, its consequences for the calculation of prothrombinase activity and the standardisation of heparin activity. 141 57

Laminarin sulfates were synthesized without significant degradation of the genuine laminarin chain using SO3/pyridine complex as a sulfation reagent. 6 derivatives with a degree of sulfation (d.s.) ranging from 0.30 to 2.26 could be obtained. According to methylation analysis the C-6-OH-groups of the glucose molecules were preferentially substituted, followed by the OH-groups at C-2 and C-4. The derivatives Lam S1 (d.s. = 0.30) and Lam S2 (d.s. = 0.64) showed no activity in the blood coagulation tests. With increasing d.s. the anticoagulant activity increased until an optimum d.s. of 1.49. Anticoagulant laminarin sulfates showed significant activity in the activated partial thromboplastin time (APTT) test but were less active in the anti-Factor Xa as well as anti-Factor IIa assay. Therefore, the anticoagulant activity of the synthesized laminarin sulfates is due to the interaction at an early stage of the coagulation cascade and neither to a direct inhibition of Factor Xa and IIa nor to an indirect effect mediated by antithrombin III.
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PMID:Synthesis of laminarin sulfates with anticoagulant activity. 141 69

In rabbits with experimental hypocoagulation induced by phenylin, the use of a new dosage form of vitamin K1 for intravenous injections in does of 1 and 5 mg/kg led, in contrast to vicasol in a dose of 0.4 mg/kg, to an increase of the prothrombin index after 2 hours and to its complete normalization after 4 hours. Intravenous injection of vitamin K1 into intact animals did not entail any changes in the activated partial thromboplastin time, thrombin and prothrombin time, in the content of fibrinogen and products of its biotransformation, antithrombin III activity, and fibrinolytic activity or in the count of platelets and their aggregation capacity.
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PMID:[The effect of a new drug form for the intravenous administration of vitamin K1 on the blood coagulation system]. 142 49

Hemostatic profiles were evaluated in 15 healthy dogs immediately before and 24 hours after celiotomy for routine ovariohysterectomy. Prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin degradation products, antithrombin III activity, platelet count, and hemogram were measured. There were no significant changes in prothrombin time, activated partial thromboplastin time, fibrin degradation products, antithrombin III activity, or platelet count. Fibrinogen concentration was significantly higher following surgery. Postoperative leukocyte differential counts were typical of stress leukograms, and were characterized by leukocytosis, neutrophilia, lymphopenia and eosinopenia. Mild decreases in packed cell volume, red blood cell count and hemoglobin concentration were consistent with minor blood loss during surgery or fluid retention and hemodilution postoperatively. It was concluded that celiotomy and routine ovariohysterectomy in healthy dogs did not alter hemostatic profiles 24 hours after surgery. Abnormal postoperative hemostatic profiles should not be attributed to surgery alone; other causes of abnormal hemostatic profiles should be investigated.
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PMID:Preoperative and postoperative hemostatic profiles of dogs undergoing ovariohysterectomy. 142 39

Ten patients with osteoarthritis were treated in an open study with galactosaminoglucuronoglycan sulphate for 60 days (800 mg b.i.d. per os). The following haemostatic indices were measured before and after treatment: platelet count, adhesion and aggregation; prothrombin time and activity; partial thromboplastin time and antithrombin III. Total and HDL cholesterolemia, triglycerides, arterial pressure and heart rate were also measured. No blood coagulation index was found to be significantly altered in treated patients. In addition, neither variations from the normal limits of lipidemic and cardiocirculatory values nor adverse effects related to treatment were reported. Although the study was carried out in a limited population, these findings show that GGG does not interfere with the coagulation process and, from a more general point of view, they confirm its excellent tolerance.
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PMID:[The possible effects of galactosaminoglucuronoglycan sulfate on blood coagulation processes]. 143 2

Researchers from Gainesville, Florida compared data on 20 women who were randomly assigned the triphasic oral contraceptive (OC) Triphasil (ethinyl estradiol and levonorgestrel) with data on 24 women who were randomly assigned the triphasic OC Ortho-Novum (ethinyl estradiol and norethindrone) and data on 8 women who were controls to evaluate these 2 triphasic OCs' effects on coagulation and anticoagulation factors. They measured these factors at baseline and 6 and 12 months after beginning OC use. Both OCs significantly reduced prothrombin time (Triphasil at 6 and 12 months, p.001; Ortho-Novum at 6 months, p01, and at 12 months, p.001). They also decreased partial thromboplastin time (Triphasil at 6 months, p.01), and at 12 months, p.001; Ortho-Novum at 6 months, p.01). Both OCs significantly increased Factor XII after 6 and 12 months (Triphasil p.001 and p.01 for controls and p.05 from baseline, respectively; Ortho Novum p.01). Ortho-Novum considerably increased fibrinogen antigen at 6 and 12 months (p.05 and p.001 from baseline and p.05 for controls, respectively) while Triphasil increased it only at 12 months (p.05). Platelet counts remained the same. Ortho-Novum markedly increased antithrombin III activity after 6 months (p.05). Even though neither OC changed antithrombin III antigen, they did significantly increase alpha-1-antitrypsin antigen and plasminogen antigen and activity at 6 and 12 months as well as alpha-2-antiplasmin antigen at 12 months. Ortho-Novum increased alpha-s-antiplasmin antigen at 12 months. No great differences in coagulation or anticoagulation factors existed between the OCs. The mean values were within reference ranges. These results showed that the OCs had the same, limited effects on hemostasis and changes in coagulation factors offset changes in anticoagulation factors.
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PMID:Changes in coagulation and anticoagulation in women taking low-dose triphasic oral contraceptives: a controlled comparative 12-month clinical trial. 144 74

To determine if rhesus monkeys (Macaca mulatta) could serve as a model for studying the role of the contact system in the pathophysiology of human infections, we compared structural, kinetic, and functional characteristics of plasma prekallikrein and its activation products in rhesus and humans. Three prekallikrein variants (85-, 89- and 93-kDa) were revealed in rhesus plasma as compared with the two variants (85- and 88-kDa) in human plasma by immunoblotting with the monoclonal antibody MAb 13G11. The prekallikrein concentration in rhesus plasma was 1.5-fold that in human plasma as determined by computerized immunoblot analyses (CIBA) and amidolytic activity. The electrophoretic mobility of prekallikrein from plasma of both species increased after deglycosylation. Inhibition of prekallikrein activation by MAb 13G11 was 55% (rhesus plasma) and 76% (human plasma), with similar inhibition curves. Immunoblots of activated rhesus plasma showed prekallikrein, complexes of kallikrein with C1 inhibitor, alpha 2-macroglobulin and approximately 60-kDa inhibitor(s) (viz. antithrombin III), and 45-kDa fragments, like those in activated human plasma. Concentrations and molecular masses of factor XII and high molecular weight kininogen were similar in rhesus and human plasma. The activated partial thromboplastin time (APTT) and prothrombin time were 20.1 +/- 1.6 and 9.7 +/- 0.3 s for rhesus and 32.0 +/- 5.6 and 12 +/- 0.5 s for human plasma. Human and rhesus APTTs were similar when prekallikrein concentrations in human and rhesus plasma became alike by adding human purified prekallikrein.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Structure, kinetics, and function of human and rhesus plasma prekallikreins are similar. 145 99

The Atherosclerosis Risk in Communities Study measured hemostatic variables in nearly 16,000 men and women, aged 45 to 64 years, from four US communities. This report, based on the first 12,681 participants, presents distributions of fibrinogen concentration, factor VII activity, factor VIII activity, von Willebrand factor antigen, protein C antigen, antithrombin III activity, and activated partial thromboplastin time. Many of the hemostatic variables differed between blacks and whites, and by sex and age. For example, compared to whites, blacks had higher mean values of fibrinogen, factor VIII, von Willebrand factor, and antithrombin III, and lower mean values of protein C. Some seasonal fluctuations in hemostatic variables were noted; most notably, mean values of factor VII were lowest and protein C were highest in subjects examined in the summer compared to those examined during the other seasons. These results provide population-based reference values on blacks and whites for those interested in the relation of hemostasis to disease.
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PMID:Distributions of hemostatic variables in blacks and whites: population reference values from the Atherosclerosis Risk in Communities (ARIC) Study. 145 14


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