Inhibition of the hemorrhagic and proteolytic activities of Lansberg's hognose pit viper (Porthidium lansbergii hutmanni) venom by opossum (Didelphis marsupialis) serum: isolation of Didelphis marsupialis 0.15Dm fraction on DEAE-cellulose chromatography.

Earlier studies have revealed the ability of sera from several mammals to neutralize the toxic effects of snake venom. The Venezuelan opossum (Didelphis marsupialis) is one that has been found to inhibit hemorrhagic and proteolytic activities of venoms from many species of snakes. In this article it is shown that the opossum sera and its 0.15DM fraction were able to completely neutralize both hemorrhagic and hydrolysis (proteolysis) of casein effects induced by venom of the Lansberg's hognose pit viper (Porthidium lansbergii hutmanni). We have used DEAE-cellulose ion exchange chromatography to collect protein fractions from D. marsupialis sera which were able to defend mice from the lethal effects of P.l. hutmanni venom. The fractions separated were homogeneous by conventional electrophoresis using SDS-PAGE. The protein bands obtained contained molecular weights of approximately 6 to 220 kDa. These results revealed the presence of proteases inhibitors in the opossum sera fractions and the inhibition of venom activity by opossum sera suggesting a reciprocal adaptation at the molecular level.

Alterations in the ultrastructure of cardiac autonomic nervous system triggered by crotoxin from rattlesnake (Crotalus durissus cumanensis) venom.

This study explored the toxic effects of crotoxin isolated from Crotalus durissus cumanensis venom on the ultrastructure of mice cardiac autonomic nervous system. Mice were intravenously injected with saline (control group) and crotoxin diluted in saline venom (study group) at a dose of 0.107 mg/kg mouse body weight. Samples from the inter-ventricular septum were prepared for electron microscopy after 6 h (G1), 12 h (G2), 24 h (G3) and 48 h (G4). The G1 group showed some cardiomyocyte with pleomorphic mitochondria. Capillary swollen walls, nerve cholinergic endings with depleted acetylcholine vesicles in their interior and other depletions were observed. A space completely lacking in contractile elements was noticed. The G2 group demonstrated a myelinic figure, a subsarcolemic region with few myofibrils and nervous cholinergic terminal with scarce vacuoles in their interior. The G3 group demonstrated a structure with a depleted axonic terminal, mitochondrias varying in size and enhanced electron density. In addition, muscular fibers with myofibrillar structure disorganization, a depleted nervous structure surrounded by a Schwann cell along with an abundance of natriuretic peptides, were seen. An amyelinic terminal with depleted Schwann cell and with scarce vesicles was also observed. Finally, axonic lysis with autophagic vacuoles in their interior and condensed mitochondria was observed in the G4 group. This work describes the first report of ultrastructural damage caused by crotoxin on mice cardiac autonomic nervous system.

Inhibition of collagen, and thrombin-induced platelet aggregation by Lansberg's hognose pit viper (Porthidium lansbergii hutmanni) venom.

The Porthidium genus is represented by the P. lansbergii rozei and P. lansbergii hutmanni (Plh) subspecies in Venezuela. The venom components of these have been little studied, probably due to the low incidence of reported accidents, although acute and serious local effects such as invasive edema and disseminated ecchymosis are present during human envenonation. The aim of this work was to characterize the in vitro effects of crude P. l. hutmanni venom, and its fractions, on platelet aggregation triggered by two physiologic agonists: thrombin and collagen. The effects of thrombin and collagen were observed on a platelet-rich plasma (PRP) solution (3 x 10(5) platelets/microL) using serial dilutions of P. l. hutmanni venom (0.625-40 microg). The crude venom was fractionated by anionic exchange chromatography and two peaks obtained. Crude venom and both fractions were highly inhibitory on platelet aggregation mediated by the two agonists. The anti-aggregating dose (AD(50)) for both agonists was determined. PRP collagen-triggered aggregation was most inhibited by the crude venom (AD(50) = 0.67 microg) when compared with PRP thrombin-triggered aggregation (AD(50) = 4.92 microg). Collagen-induced aggregation was more intensely inhibited by venom than thrombin-induced aggregation. In conclusion, to specify the inhibition mechanisms involved for each of the active components in the venom from these subspecies, we must characterize and purify the inhibitors of aggregation from P. l. hutmanni venom, with the purpose of suggesting new pharmacological substances to be incorporated into the therapeutic arsenal to treat hemostatic pathologies related to high levels of platelet aggregation.