The neuromuscular activity of Micrurus pyrrhocryptus venom and its neutralization by commercial and specific coral snake antivenoms.

The neuromuscular activity ofMicrurus pyrrochryptus venom was studied in chick biventer cervicis (BC) and mouse phrenic nerve-diaphragm (PND) preparations. The venom (0.5-50µg/ml) caused irreversible, time- and concentration-dependent blockade, with BC being more sensitive than PND (50% blockade with 10µg/ml in 22±;3min and 62±4min, respectively; mean±SEM, n=6; p<0.05). In BC preparations, venom (0.5µg/ml) progressively abolished ACh-induced contractures, whereas contractures to exogenous KCl and muscle twitches in curarized preparations were unaffected. The venom neither altered creatine kinase release (venom: 25.8±1.75IU/l vs control: 24.3±2.2IU/l, n=6, after 120min), nor it caused significant muscle damage (50µg of venom/ml vs control: 3.5±0.8% vs 1.1±0.7% for PND; 4.3±1.5% vs 1.2±0.5% for BC, n=5). The venom had low PLA(2) activity. Neurotoxicity was effectively neutralized by commercial Micrurus antivenom and specific antivenom. These findings indicate that M. pyrrhocryptus venom acts postsynaptically on nicotinic receptors, with no significant myotoxicity.

Estudo comparativo entre duas técnicas de dosagem de metemoglobina (MHb) / Comparative study between two techniques of methemoglobin (MHb) determination

A hemoglobina é a proteína responsável pelo transporte de oxigênio, função vital ao organismo. A oxidação de um átomo de ferro da hemoglobina resulta na formação de MHb, condição que pode ser de origem congênita ou adquirida. Metemoglobinemia é caracterizada quando uma concentração superior a 2% (Evelyn e Malloy, 1938; Hegesh et al., 1970) ou a 3,8% (Naoum et al.,2004) da hemoglobina encontra-se na forma oxidada. O objetivo desta pesquisa, aprovada pelo Comitê de Ética em Pesquisa da UNISO,foi verificar a correlação existente entre a técnica de Hegesh et al. (1970) com a recente proposta por Naoum et al. (2004), atravésdo coeficiente de correlação (r) de Pearson. Os voluntários (50 estudantes da UNISO) que participaram da pesquisa após assinarem o Termo de Consentimento Livre e Esclarecido, eram hematimetricamente normais e não-fumantes. Obteve-se um coeficiente decorrelação linear próximo a 1 (r=0,93), indicando correlação positiva entre os métodos e estatisticamente significativa pelo teste t-Student (p<0,01). Embora não se possa afirmar que exista diferença estatística entre as duas técnicas, dado que são medidas em escalasdiferentes, conclui-se que a técnica de Naoum é vantajosa sobre a de Hegesh quanto à estabilidade, toxicidade de reagentes, riscos ao analista e custos.

The hemoglobin is a protein responsible by the transport of oxygen, vital function to the organism. Methemoglobin (MHb) occurs when the hemoglobin is oxidized to the ferric form, condition that could have genetic or acquired source. Methemoglobinemia is characterized when level higher to 2% (Evelyn e Malloy, 1938; Hegesh et al., 1970) or to 3,8% (Naoum et al., 2004) of hemoglobin is oxidized. The objective of this study, approved by Committee for Ethics in Clinical Research (UNISO) and after obtained the Informed Consent, was to verify the existent correlation between the Hegesh et al. (1970) with the recent proposed by Naoum et al. (2004) techniques, by using of Person’s coefficient (r). The volunteers (50 students from UNISO) were with normal hematimetric values and were no-smokers. A coefficient of linear near to 1 was obtained (r=0,93), indicating a significative (p<0,01) and positive correlation between the techniques. Although the techniques could not be compared statistically, since the scale are not equals, we can conclude that the Naoum technique is advantageous on the Hegesh relative to the analytical stability, reagents toxicity, risks to analyst and costs.