Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of human activated protein C (APC) on tissue plasminogen activator (tPA)-induced fibrinolysis was studied in cell free plasma and in a system of purified components. Clots were produced by adding plasma or a solution of fibrinogen and plasminogen to the wells of a microtiter plate containing small separated aliquots of Ca2+, thrombin, and tPA, plus and minus APC. Initial clotting and subsequent fibrinolysis were monitored continuously by turbidity. The lysis time of dialyzed normal human plasma (NHP) was longer than that of dialyzed barium citrate-adsorbed plasma (BAP). APC had no effect on the lysis time of BAP but shortened the lysis time of NHP to that of BAP. Two fractions were produced from material eluted from the barium citrate pellet by precipitation of selective components with polyethylene glycol 8000 (PEG). One fraction comprised materials which precipitated at 5% PEG (5% PF) and the other materials which precipitated between 5 and 40% PEG (5-40% PF). Both fractions together, but neither alone, prolonged the lysis time of BAP, an effect which could be reversed by APC. Fractionation of the 5% PF showed that the component with the required activity has properties of the procoagulant surface and can be replaced with vesicles of phosphatidylcholine/phosphatidylserine (PCPS). In addition, the 5-40% PF can be replaced with either the combination of purified coagulation Factors II, IX, and X or Factor II plus the prothrombin activator Factor Xa. When Factor Xa was used as the activator in BAP plus PSPC vesicles, a dose-dependent saturable increase in lysis time was observed with a half-maximal increase occurring at 32 pM Factor Xa. This effect was eliminated by APC. In a system of purified components comprising PCPS vesicles, Factors V and II, protein S, plasminogen and fibrinogen; the prothrombin activators Factor Xa and ecarin both induced a prolongation of the lysis time. APC prevented prolongation by Factor Xa but not by ecarin. The time courses of the generation of thrombin and plasmin during fibrinolysis of clots produced from systems of purified components in the presence and absence of APC, and with Factor Xa as the prothrombin activator, were determined by standardized activity assays using chromogenic substrates. In the absence of APC the lysis time was 145 min, and prothrombin was quantitatively converted to thrombin. In the presence of APC, however, the lysis time was reduced to 100 min with no evidence for the activation of prothrombin.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The effect of activated protein C on fibrinolysis in cell-free plasma can be attributed specifically to attenuation of prothrombin activation. 847 6

Coagulation factors increase and fibrinolysin activity decreases in pregnant women. While the nett change in thrombotic tendency is unmeasured, venous thromboembolism increases five-fold in this group. We measured thrombus formation in vein and artery on standard platinum wires in 45 near-term pregnant rats, 19 pregnant for the first time and 26 for the second time, and in 33 never-pregnant controls. No significant increase in arterial thrombus occurred in the pregnant rats. Venous thrombus, however, increased by 65% in rats pregnant for the first time and 176% in those pregnant for the second time, compared to never-pregnant animals. Their mean increase in coagulation factors VIII, X, V, VII and II varied from 165 to 268%. Factor VIII level (r = 0.59, p < 0.05) correlated with venous thrombosis level, but the rarity of spontaneous thrombosis did not permit the limits of risk to be determined. Factors VII, X and V showed little correlation with thrombus weight (r = < 0.16) and Factor II an insignificant one. Monitoring factor VIII levels in pregnant women might help identify a group at risk of thromboembolism and establish a threshold for prophylactic intervention.
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PMID:Quantitation of the thrombotic effects in artery and vein of the increase in coagulation factors during normal pregnancy in the rat. 927 13

The purpose of this study was to determine whether chronic thyroid hormone suppression therapy (THST) is prothrombotic. We obtained blood samples from 14 thyroid cancer patients while on THST and after they had become hypothyroid for radioiodine whole-body scanning and therapy. Prothrombin fragment 1 + 2, fibrinogen, factor VIII, antithrombin, tissue plasminogen activator antigen (tPA), plasminogen activator inhibitor 1 (PAI-1), PAI-1/tPA, and C-reactive protein were significantly (P < 0.05) higher in the hyper- than in the hypothyroid state, whereas protein C and plasmin-antiplasmin complexes were significantly lower during the hyperthyroid period. When the 10 female patients were hyperthyroid, their levels of prothrombin fragment 1 + 2, fibrinogen, protein S, antithrombin, tPA, PAI-1, and PAI-1/tPA were significantly higher (P </= 0.05) than in healthy female controls, whereas when the female patients were hypothyroid, their antithrombin and plasmin-antiplasmin were lower and their protein S was higher than in controls. Factor II, plasminogen, and D-dimer were not significantly affected by the thyroid status in either assessment. In conclusion, we found evidence that the majority of patients treated with THST have a prothrombotic profile.
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PMID:Is thyroid hormone suppression therapy prothrombotic? 1535 49