Toxicon : official journal of the International Society on Toxinology
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Comparative Study
Antiallodynic effect and side effects of Phα1β, a neurotoxin from the spider Phoneutria nigriventer: comparison with ω-conotoxin MVIIA and morphine.
Phα1β is a potent toxin obtained from the spider Phoneutria nigriventer that blocks neuronal voltage-sensitive Ca(2+) channels. This study compared the antiallodynic effects of Phα1β, ω-conotoxin MVIIA and morphine in mice and their side effects in rats. Mechanical allodynia was measured in mice receiving single intrathecal administration of Phα1β, ω-conotoxin MVIIA or morphine before or after the incisional plantar procedure. ⋯ In conclusion, preemptive administration Phα1β in mice induced longer antiallodynic effect than ω-conotoxin MVIIA and morphine. Phα1β also induced a longer mechanical antiallodynic effect than ω-conotoxin MVIIA and morphine when used after the surgical incision. The present results suggest that Phα1β has a potential application in the management of postoperative pain with low side effects.
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The aim of this study was to determine the cause of sudden deaths in sheep in the Anari Valley of the state of Rondônia, in northern Brazil. In one outbreak, sheep were placed in an area where the owner had cut Amorimia (Mascagnia) sepium and let it dry for two days. Fourteen out of 35 sheep died with few outward clinical signs observed over a period of about 10 h after the ingestion of the dry plant. ⋯ Fibrosis, neovascularization and infiltration by mononuclear inflammatory cells were observed in the sheep that ingested the plant for 33 days. Vacuolar-hydropic degeneration was observed in the epithelial cells of renal tubules of four sheep. It is concluded that A. sepium is responsible for sudden deaths in sheep.
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From six Conus species (Conus coronatus, Conus lividus, Conus mozambicus f. lautus, Conus pictus, Conus sazanka, Conus tinianus) collected off the eastern coast of South Africa the venoms were analyzed using MALDI-TOF mass spectrometry. Between 56 and 151 molecular masses most in a range of 1000 to 2500 Da, were identified. Among the six venoms, between 0 and 27% (C. coronatus versus C. sazanka) of the peptide masses were found to be similar. ⋯ Posttranslational modifications include C-terminal amidation and tyrosine sulfation. The new peptide is a member of the α-conotoxin family that are competitive antagonists of nAChRs. Phylogenetic analysis of the 16S RNA from numerous Conus species has clarified the evolutionary position of endemic South African Conus species and provided the first evidence for their close genetic relationships.
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Conus californicus belongs to a genus of marine gastropods with more than 700 extant species. C. californicus has been shown to be distantly related to all Conus species, but showing unusual biological features. We report a novel peptide isolated from C. californicus with a significant inhibitory action over neuronal voltage-gated calcium channels. ⋯ In the HPLC purification procedure, the venom fraction eluted in the first 10-15 min produced a significant decrease (54% ± 3%) of the Ca(2+) current in Xenopus laevis oocytes transfected with purified rat-brain mRNA. A specific peptide obtained from the elution at 13 min decreased the Ca(2+) current in the adult rat dorsal-root ganglion neurons in a primary culture by 34% ± 2%. The cysteine pattern of this peptide corresponds to the framework XVI described for the M-superfamily of conopeptides and is unprecedented among Conus peptides acting on Ca(2+) channels.
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North American rattlesnake envenomations commonly produce defibrination, coagulopathy and/or thrombocytopenia, which may be reversed following treatment with Crotalidae Polyvalent Immune Fab Ovine (FabAV). Despite initial resolution with FabAV, late onset or recurrence of venom-induced hematologic effects may occur. Time at which onset of late hematotoxicity may first be detected is unknown. The purpose of this study was to identify the incidence and time of onset of recurrent or new late hypofibrinogenemia, coagulopathy, or thrombocytopenia in a cohort of rattlesnake envenomation patients seen in outpatient follow-up after treatment with FabAV, and to report hematologic outcomes in these patients. ⋯ Recurrent and delayed onset of hematologic toxicity in rattlesnake envenomation victims treated with FabAV is common. Follow-up more than three days after treatment is necessary to detect all cases of late hematologic toxicity.