Navegando por Palavras-chave "coagulopathy"

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    In vivo characterization of Lopap, a prothrombin activator serine protease from the Lonomia obliqua caterpillar venom
    (Elsevier B.V., 2001-06-01) Reis, C. V.; Farsky, SHP; Fernandes, B. L.; Santoro, M. L.; Oliva, MLV; Mariano, M.; Chudzinski-Tavassi, A. M.; FAPESP; Universidade de São Paulo (USP); Butantan Inst; Universidade Federal de São Paulo (UNIFESP)
    Increasing occurrence of hemorrhagic syndrome in man, caused by contact with Lonomia obliqua caterpillars, has been reported in Southern Brazil in the past 10 years. the L. obliqua venom causes a severe consumptive coagulopathy, which can lead to hemorrhagic syndrome. L. obliqua prothrombin activator protease (Lopap) is a 69-kDa prothrombin activator serine protease isolated from L. obliqua caterpillar bristle extract, which is able to evoke thrombus formation, unclottable blood, and fibrinogen depletion when injected into the blood stream of rats. the purified protein generated thrombin from prothrombin, able to clot purified human fibrinogen and plasma. A decrease in platelet count and inhibition of collagen-induced platelet aggregation were observed, as well as leukocyte infiltration in the lungs. Ln addition, we observed congestion and hemorrhage in renal glomeruli and necrosis in renal distal tubules. These data support the hypothesis that Lopap contributes to the clinical syndrome caused by human contact with L. obliqua, most probably through prothrombin activation, resulting in a consumption coagulopathy. (C) 2001 Elsevier B.V. All rights reserved.
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    A prothrombin activator serine protease from the Lonomia obliqua caterpillar venom (Lopap) biochemical characterization
    (Elsevier B.V., 2001-06-01) Reis, C. V.; Portaro, FCV; Andrade, S. A.; Fritzen, M.; Fernandes, B. L.; Sampaio, CAM; Camargo, ACM; Chudzinski-Tavassi, A. M.; FAPESP; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    Lonomia obliqua venom causes a severe consumptive coagulopathy, which can lead to a hemorrhagic syndrome. the crude bristles extract displays a procoagulant activity due to a Factor X and to a prothrombin activating activity. Here, we describe a 69 kDa prothrombin activator serine protease purified from L. obliqua caterpillar bristle extract using gel filtration (Sephadex G 75) and HPLC (C-4 column). the purified protein was able to activate prothrombin in a dose-dependent manner, and calcium ions increased this activity. the prothrombin-derived fluorogenic peptide (Abz-YQTFFNPRTGSQ-EDDnp) had its main cleavage site at the Arg-Thr bond. the kinetic parameters obtained for this substrate were K-mapp. of 4.5 muM, k(cat) of 5.32 s(-1), and a k(cat)/K-mapp of 1.2 x 10(6) M-1 s(-1). the prothrombin fragments generated by the purified enzyme corresponded to the molecular masses of prethrombin 2, fragment 1, fragment 2, and thrombin as seen in SDS-PAGE. the thrombin generated was able to clot purified fibrinogen. the partial amino acid sequence of the purified protein, named Lopap (L. obliqua prothrombin activator protease), showed no similarity to any known prothrombin activator. (C) 2001 Elsevier B.V. All rights reserved.