PubMed · 14449283
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C HOUGIE. 1962. A simple assay method for factor X (Stuart-Prower factor).. https://doi.org/10.3181/00379727-109-27328
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A mixed film bearing nanoscale domains of one chemical functionality surrounded by another chemical functionality is shown to prolong material-induced coagulation of whole human blood plasma. In comparison, surfaces with uniform silane chemistry or physical mixtures of control surfaces bearing two different, uniform silane chemistries are found to be much more efficient activators of plasma coagulation on a per-unit-area basis. Binary mixed films are deposited on glass substrates by the sequential adsorption of 0.0001% 3-aminopropyltriethoxysilane (APS) followed by 0.1% n-butyltrichlorosilane (BTS). Creation of APS islands in a sea of BTS is confirmed by atomic force microscopy in friction mode. Results suggest that some yet-to-be-determined interfacial phenomena, perhaps associated with protein adsorption near the interface, may be altered by this nanoscale spatially distributed chemical heterogeneity, causing a decrease in contact activation.
BACKGROUND: Thrombin is a primary inducer of thrombus formation by activations of coagulation cascade and platelet aggregation. Hitherto, several types of thrombin inhibitors have been developed for therapeutic purpose. OBJECTIVES: We prepared modified thrombin (M-thrombin) and modified anhydrothrombin (M-anhydrothrombin) by chemical modification of carboxyl groups of thrombin and anhydrothrombin, respectively, to present a new strategy for a potent antiplatelet-anticoagulant agent and new tools for investigation of thrombin functions. RESULTS: M-anhydrothrombin retained high affinity for factor VIII (FVIII), but demonstrated lower affinity than anhydrothrombin for fibrinogen and factor V (FV). Both M-anhydrothrombin and anhydrothrombin prolonged activated partial thromboplastin time (APTT) without affecting prothrombin time, and M-anhydrothrombin prolonged APTT much more than anhydrothrombin. M-anhydrothrombin also retained affinity for the recombinant extracellular domain peptide of protease-activated receptor 1 (PAR1). M-thrombin exhibited marginal clotting activity (4% of thrombin), but induced platelet aggregation in platelet-rich plasma without forming a fibrin clot, which was completely suppressed by anti-PAR1 antibody (ATAP2) and by M-anhydrothrombin, but not by anhydrothrombin. These results indicate that M-thrombin induced platelet aggregation through the activation of PAR1, and M-anhydrothrombin inhibited this process completely. In contrast, neither M-anhydrothrombin nor anhydrothrombin apparently inhibited thrombin-induced platelet aggregation. Only in the presence of the Gly-Pro-Arg-Pro (GPRP) peptide that inhibits polymerization of fibrin, M-anhydrothrombin completely inhibited thrombin-induced platelet aggregation. CONCLUSION: M-thrombin is PAR1-specific and M-anhydrothrombin is FVIII- and PAR1-specific derivatives, and thereby, are new tools as specific agonist and antagonist, respectively, of PAR1. Furthermore, M-anhydrothrombin may be an attractive model for development of a potent anticoagulant-antiplatelet agent.
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