Journal of Venom Research最新文献

Echis carinatus (saw-scaled viper) produces potent hemorrhagic venom that causes the development of apoptotic and necrotic tissues. In this study, we used polyethyleneimine (PEI) to enhance cellular adherence, and to determine whether the substrate attachment influenced the survival of cells treated with crude E. carinatus venom. Human embryonic kidney (HEK) 293T cells were grown for 18hr in tissue culture plates with or without polyethyleneimine (PEI), and were then stimulated with crude E. carinatus venom for 3 or 12hr. HEK 293T cells grown without PEI displayed a robust oxidative response to corresponding substrate detachment, loss of plasma membrane integrity and decreased cell viability. Cells grown on PEI adsorbed substrates demonstrated prolonged substrate attachment resulting in significantly higher cell viabilities. These observations suggest that the cytotoxicity of crude E. carinatus venom is dependent upon cellular detachment.

Venom phospholipases A2 (PLA(2)) are associated with neurotoxic, myotoxic, cardiotoxic, platelet aggregation, and edema activities. A PLA(2) (Drs-PLA(2)) was purified from Daboia russelii siamensis venom by a two-step purification procedure consisting of size-exclusion, followed by anion exchange high performance liquid chromatography (HPLC). The molecular weight of the Drs-PLA(2) was 13,679Da, which was determined by MALDI-TOF mass spectrometry. Its N-terminal amino acid sequence was homologous to basic PLA(2)s of viperid snake venoms. The Drs-PLA(2) had indirect hemolytic and anticoagulant activities, cytotoxic activity with a CC(50) of 65.8nM, and inhibited SK-MEL-28 cell migration with an IC(50) of 25.6nM. In addition, the Drs-PLA(2) inhibited the colonization of B16F10 cells in lungs of BALB/c mice by ∼65%.

The neurotoxicity of a methanolic extract of toad (Rhinella schneideri) poison was examined in chick biventer cervicis preparations. The methanolic extract (1, 3, 10 and 30µg/ml) caused concentration-dependent blockade at the three highest concentrations (time for 50% blockade, mean±SEM: 84±10, 51±3 and 12±0.8min for 3, 10 and 30µg/ml, respectively; n=6-8 each) that was preceded by significant, transient facilitation at 10μg/ml. Contractures to exogenous ACh (110μM) or KCl (20mM) were unaffected by the blockade. In curarized (d-Tc, 1μg/ml) preparations, the extract (10µg/ml) caused complete, irreversible blockade that persisted after extensive washing. The extract did not significantly alter the creatine kinase release or morphology of biventer cervicis muscle. These results indicate that the methanolic extract of R. schneideri poison acts primarily presynaptically to enhance neurotransmitter release in this avian preparation.

Hump-nosed pit vipers (Genus Hypnale) are venomous snakes from South India and Sri Lanka. Envenoming by Hypnale species may cause significant morbidity and is characterized by local envenoming and less commonly coagulopathy and acute renal failure. Currently there are three nominal species of this genus: H. hypnale, H. zara and H. nepa. This study investigates the biochemical and pharmacological properties of the venoms from the three Hypnale species in Sri Lanka. The three Hypnale venoms had similar chromatographic profiles using reverse phase high performance liquid chromatography and fractions with procoagulant activity were identified. Hypnale venoms had potent cytotoxicity in cultured rat aorta smooth muscle cells with similar IC(50) values. The venoms had weak neurotoxic and myotoxic activity in the isolated chick biventer muscle preparation. They had mild procoagulant activity with close MCC(5) values and also phospholipase activity. Locally available polyvalent antivenom did not neutralise any venom effects. The study demonstrates that the three Hypnale venoms are similar and cytotoxicity appears to be the most potent effect, although they have mild procoagulant activity. These findings are consistent with clinical reports.

Alternative treatments for snake bite are currently being extensively studied, and plant metabolites are considered good candidates for such purpose. Here, the ability of a crude ethanolic extract of Hypericum brasiliense plant in neutralizing Bothrops jararaca snake venom was investigated by in vitro (coagulation, hemolysis or proteolysis) and in vivo (hemorrhage, lethality and edema) biological assays. We describe for the first time the ability of H. brasiliense extracts to inhibit some pharmacological effects of a Brazilian snake venom. Inhibitory assays were performed by incubating B. jararaca venom with H. brasiliense extracts for 30min at room temperature before the assays were performed. The results showed that H. brasiliense extracts impaired lethality, edema, hemorrhage, hemolysis, proteolysis as well as fibrinogen or plasma clotting induced by B. jararaca venom. This indicates that H. brasiliense extracts can provide promising agents to treat B. jararaca envenomation.

Hexane (HEX), dichloromethane (DM), ethyl acetate (EA) and methanol (M) extracts (0.1, 0.2 and 0.4mg/ml) were obtained via Soxhlet from Plathymenia reticulata barks (Pr). These extracts were evaluated against the myotoxicity (58%) and the irreversible in vitro neuromuscular blockade of Bothrops jararacussu (Bjssu) venom (40μg/ml) in a mouse phrenic-nerve diaphragm preparation, by using light-microscopy and conventional myographic techniques. Thin layer chromatography (TLC) was used to access the basic composition of extracts. The efficacy of the extracts was analyzed by Student's t-test or repeated measures ANOVA. The significance level was set at 5%. The Pr extracts showed a higher polyphenols content (3.75%), from which tannins take part, around 20 times more than flavonoids content (0.16%). Qualitatively, via TLC, DM and EA extracts showed higher tannins concentration than the HEX and M extracts. Pharmacologically, at 0.4mg/ml, DM was more effective (92 ± 6.2%) than EA (81.3 ±10%) = HEX, 77.2 ±4.7%) > M (54 ±10%) against the toxic effects of the venom. Morphologically, DM extract preserved intact 52.8% of the muscle fibers in the presence of the venom. We concluded that P. reticulata extracts are able to inhibit toxic effects of B. jararacussu venom, whose protective mechanism could be mediated by tannins.

The demand for spider venom increases along with the growing popularity of venoms-based research. A deeper understanding of factors that influence the venom yield in spiders would therefore be of interest to both commercial venom suppliers and research facilities. The present study addresses the influence of several factors on the venom yield by systematically analyzing the data obtained from 1773 electrical milkings of the Australian theraphosid spider Coremiocnemis tropix. Gender and ontogenesis were found to cause a major effect on the venom yield, as adult female C. tropix yielded significantly more venom than adult males. During ontogenesis, the venom yield increased with increasing size of the spiders. Furthermore, a significant reduction in the venom yield during the 50-day time interval preceding a molt was found. On the other hand, extended milking intervals (up to 449 days) and different states of nutrition (as an indication of how well the spider was fed) did not significantly affect the venom yield. Overall, the present findings suggest that venom production in spiders is carefully balanced between the demand for venom and the energy costs associated with its production. It can therefore be concluded that, in line with the venom optimization hypothesis, venom is a precious resource for spiders, which have implemented control mechanisms to ensure economical venom production and usage.

Bungarotoxin present in Bungarus caeruleus (BC) causes life threatening respiratory muscle paralysis. Deep coma and hypokalaemia have been observed in a significant proportion of patients, but the cause is unknown. We postulate the likely mechanism behind these two phenomena. We studied clinical details of two patients admitted with deep coma and performed electroencephalograms (EEG) and brain stem auditory and visual evoked potentials (BAEP and VEP). Daily serum potassium was measured along with urinary potassium excretion as a marker of total extracellular body potassium. Both patients had no brain stem reflexes on admission and the EEG revealed absent alpha and delta activity and presence of dominant theta activity. Alpha rhythm returned on the 3(rd) day in one patient, while in the other it did not, and the latter patient died on the 13(th) day due to disseminated intravascular coagulation. BAEP were delayed and VEP were absent in the deceased patient. Both had low serum potassium and low urinary potassium excretion. Replacement of potassium (up to 1.5mmol/kg/day) did not improve serum potassium and urinary potassium excretion. Absent alpha and delta activity in EEG and delayed BAEP and absent VEP are suggestive of a central action of the venom on both the cortical and brain stem neurones. Persistently low serum potassium and reduced urinary potassium excretion are suggestive of intracellular shift as the causative mechanism of hypokalaemia.

Venom from male and female specimens of the medically important Venezuelan scorpion Tityus nororientalis have been compared. Males showed a significantly higher venom yield (2.39mg/individual) compared to female scorpions (0.98mg/individual). Female venom was significantly more toxic than that of males, with a median lethal dose (LD(50)) in C57BL/6 mice of 9.46 μg venom protein/gm body weight [95% confidence interval (8.91-9.94)] whereas LD(50) for males was 13.36(12.58-14.03) μg/gm. Mass spectral analyses by MALDI-TOF revealed differences in venom composition between males and females. From a clinical standpoint, the time course of toxicity course indicated a tendency, in the case of the female venom, to elicit the earlier occurrence of severe signs such as sialorrhea, dyspnea (bradypnea/apnea) and exophthalmus particularly in the late toxicity phase. Female venom was significantly less efficient than male venom to inhibit the binding of anti-T. discrepans antibodies to immobilized T. discrepans venom in ELISA assays, suggesting sex-related differences in the bioactive surfaces of T. nororientalis toxins. These results indicate that males and females of T. nororientalis produce venoms with different composition and activity which may have epidemiological implications.

Heparin has been shown to antagonize myotoxic effects of crotaline venoms. Here a very low heparin concentration (LHC) was examined in its ability to antagonize the neurotoxic/myotoxic effects of Bothrops jararacussu venom and its phospholipase A(2) myotoxin, bothropstoxin-I (BthTX-I), in an in vitroz nerve-muscle preparation and in mice gastrocnemius. Normalization of results was done by assays with commercial antibothropic antivenom (CBA). LHC (1IU/ml) added to the incubation bath reduced by 4- and 4.5-fold (vs 2.8- and 2.5-fold by CBA) the neuromuscular paralysis, by 5.4 and 4.4-fold (vs 2.5- and 13.3-fold by CBA) the percentage of fibers damaged and by 6- and 1.7-fold (vs 30- and 1.6-fold by CBA) the CK activity induced by B. jararacussu and BthTX-I, respectively. Protamine sulphate added 15min after the incubation of the preparation with LHC+venom, avoided the LHC neutralizing effect against venom neurotoxicity. This strongly attests that given the polycationic nature of protamine, it probably complexed with the polyanionic heparin making it unattainable for binding to basic components of venom, reducing toxicity. Since heparin antagonism is generally stronger against venom effects than is myotoxin we discuss that other venom components than the BthTX-I are likely target for the antagonism promoted by the polyanionic heparin.