PubMed Health⌕ Search

Biomedical subjects

C V Reis

Publications and source records attributed to C V Reis.

6 recordsLinked to original sources
PubMed2002

Evaluation of the blood coagulation mechanism and platelet aggregation in individuals with mechanical or biological heart prostheses.

Oral anticoagulants have been widely employed to decrease thrombotic risk by reducing the levels of vitamin K-dependent clotting factors. Paradoxically, the use of oral anticoagulants also decreases the levels of natural anticoagulants (protein C and protein S), which favors the hypercoagulability state. Increased platelet activation has been reported in patients undergoing warfarin treatment. These findings have raised questions about the antagonistic effect of oral anticoagulants and their implications for hemostatic balance. The aim of this study is to determine the relationship between warfarin dosage and prothrombin time [International Normalized Ratio (INR)], platelet aggregation, vitamin K-dependent clotting factors, and protein C and protein S. Blood samples from 27 patients were analyzed, seven with mechanical prostheses and 20 with biological prostheses, and 27 controls. Multiple regression analysis showed that factor II most significantly determines the INR. Results showed that the INR, clotting factors, and protein C and protein S activity did not correlate with warfarin dosage, highlighting the need for accurate laboratory monitoring of those undergoing anticoagulant therapy.

Adolescent↗
PubMed2001

A prothrombin activator serine protease from the Lonomia obliqua caterpillar venom (Lopap) biochemical characterization.

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 Kmapp of 4.5 microM, kcat of 5.32 s(-1), and a kcat/Kmapp 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.

Amino Acid Sequence↗
PubMed2001

In vivo characterization of Lopap, a prothrombin activator serine protease from the Lonomia obliqua caterpillar venom.

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. In 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.

Animals↗
PubMedDate not supplied

Effects of lopap on human endothelial cells and platelets.

Severe consumption coagulopathy has been detected in rats after Lopap (a prothrombin activator from Lonomia obliqua caterpillar bristles) infusion and in humans after accidental contact with L. obliqua bristles. However, platelet count and antithrombin (AT) levels were only modestly affected, suggesting that a different form of blood coagulation activation may be involved in this hemorrhagic syndrome. Here we describe that Lopap had no effect on aggregation of washed human platelets induced by several agonists, suggesting that it might not impair platelet function in vivo. AT was able to inhibit the amidolytic activity of thrombin generated by incubation of Lopap with prothrombin in a purified system, which may be different from that generated by the prothrombinase complex in vivo. The surface expression of both ICAM-1 and E-selectin but not of VCAM-1 was upregulated by Lopap in cultured HUVEC, suggesting that it may behave differently from other mediators, such as thrombin and tumor necrosis factor-alpha.

Animals↗
PubMedDate not supplied

[Glycogenosis type I]

OBJECTIVE: To o present up-to-date knowledge about Glycogen storage disease type I (GSD-type I) - a disease caused by the deposit of glycogen resulting from the deficiency of the enzyme glucose-6- phosphatase - and to provide the pediatricians with the necessary information for a precocious diagnosis and an adequate conduct for those cases where this metabolic disturbance is present. METHODS: Through Medline, the most significant articles published during the last 20 years were selected from national and international journals of medicine, with special attention to dietary treatment of glycogen storage disease type I. RESULTS: The metabolism of glycogen and the metabolic consequences of glycogen storage disease type I were discussed, especially hypoglycemia, the principal metabolic disturbance of the disease. The clinical and laboratory findings are described together with the histopathology. The use of uncooked cornstarch and enteral carbohydrate infusion are the means used for the maintenance of normoglycemia. The control of hyperuricemia, hyperlipidemia and platelet disorders are other aspects of the treatment as well as the prevention of infections and the use of G-CSF for glycogen storage type Ib. Hepatic transplant and its principal indications are commented on. Hepatic adenomae, which always have the potential of malignant transformation, are the results of incomplete treatment. CONCLUSIONS: Although it occurs rarely, glycogen storage type I is an important cause of volumous hepatomegaly which is associated with hypoglycemia among the infants. The dietary treatment of this illness has significantly altered the clinical course and has improved the prognosis. Therefore it is indispensable that the general pediatrician should be familiar with the diagnosis of this clinical state so as to act rigorously in favor of the dietary control.

Journal Article↗