Propofol induced severe neuroexcitatory symptoms during emergency laparotomy.

Propofol is a widely used intravenous agent for general anesthesia and sedation. Propofol is associated with a variety of neuroexcitatory events including: opisthotonus, muscle rigidity, myoclonus, and seizures collectively termed as seizure-like phenomenon (SLP). We report a rare case of propofol induced severe neuroexcitatory symptoms at the time of induction in a young male presenting for emergency laparotomy. He developed generalized tonic- clonic seizures which resulted in dislodgement of intravenous cannula. Immediately a new intravenous cannula was inserted with difficulty during convulsions and injection thiopentone 200 mg bolus was given. Convulsions subsided within a minute. Patient remained hemodynamically stable and surgery was uneventful. He developed emergence agitation which was treated with injection midazolam. Patient recovered with no neurologic sequelae.

Uroguanylin induces electroencephalographic spikes in rats / Uroguanilina induz potenciais em espiga no eletroencefalograma de ratos

Uroguanylin (UGN) is an endogenous peptide that acts on membrane-bound guanylate cyclase receptors of intestinal and renal cells increasing cGMP production and regulating electrolyte and water epithelial transport. Recent research works demonstrate the expression of this peptide and its receptor in the central nervous system. The current work was undertaken in order to evaluate modifications of electroencephalographic spectra (EEG) in anesthetized Wistar rats, submitted to intracisternal infusion of uroguanylin (0.0125 nmoles/min or 0.04 nmoles/min). The current observations demonstrate that 0.0125 nmoles/min and 0.04 nmoles/min intracisternal infusion of UGN significantly enhances amplitude and frequency of sharp waves and evoked spikes (p = 0.03). No statistical significance was observed on absolute alpha and theta spectra amplitude. The present data suggest that UGN acts on bioelectrogenesis of cortical cells by inducing hypersynchronic firing of neurons. This effect is blocked by nedocromil, suggesting that UGN acts by increasing the activity of chloride channels.

A uroguanilina (UGN) é um peptídeo endógeno que age em receptores do tipo guanilato ciclase de membrana de células intestinais e renais aumentando a produção de GMPc e regulando o transporte epitelial de eletrólitos e água. Pesquisas recentes demonstraram a expressão deste peptídeo e de seus receptores no sistema nervosa central. O presente trabalho foi realizado com objetivo de avaliar possíveis mudanças no espectro do eletroencefalograma (EEG) de ratos Wistar anestesiados, submetidos à infusão intracisternal de uroguanilina (0.0125 nmoles/min or 0.04 nmoles/min). Os resultados apresentados no corrente trabalho demonstram que a infusão intracisternal de ambas as doses de UGN aumenta significativamente a amplitude e frequência das espículas (p = 0.03). Não foram encontradas diferenças estatísticas na amplitude absoluta dos espectros alfa ou teta. Os dados apresentados neste trabalho mostram que a UGN age na bioeletrogênese de células corticais induzindo disparo hipersincrônico de neurônios. Este efeito é bloqueado por nedocromil, sugerindo que UGN atua pelo aumento de atividade de canais de cloreto.

Neurotoxins in the polar fraction of the seaweed Galaxaura marginata (Rhodophyta, Nemaliales) / Neurotoxinas na fração polar da alga marinha Galaxaura marginata (Rhodophyta, Nemaliales)

A atividade neurotóxica das substâncias polares extraídas da alga vermelha Galaxaura marginata foi estudada por meio de ensaios farmacológicos, utilizando-se algas coletadas no canal de São Sebastião (45º25' W; 26º49' S), litoral norte do estado de São Paulo, Brasil. Altas concentrações da fração polar (PF) e da PF filtrada em membrana de 1000 Da, injetadas intraperitonealmente em camundongos, foram letais. Induzindo os animais à ataxia, desorientação e severa atonia muscular prévias à morte. Sintomas similares foram descritos para camundongos e ratos testados com aminoácidos neuroexcitatórios (NEA), sugerindo que alguns dos componentes da PF atravessam a barreira Hematoencefálica, da mesma forma que os NEA. No entanto, a análise da PF no HPLC e no espectro de massa não mostraram a presença dos aminoácidos neuroexcitatórios conhecidos, ácido Caínico, acido Domóico e NMDA. Assim concluímos que G. marginata possui substâncias com atividade letal e neurotóxica, diferentes às antes, descritas.

Neurotoxic activity of polar substances extracted from the red seaweed Galaxaura marginata was investigated in pharmacological assays, using seaweed collected at São Sebastião channel (45º25' W; 26º49' S) in the northern coast of the State of São Paulo, Brazil. High concentration of the polar fraction (PF) and PF filtered through a membrane (1000 Da) intraperitoneally (IP) injected in mice were lethal, inducing ataxia, disorientation, and severe muscle atonia prior to death. The same symptoms preceding death were described in mice and rat tested with neuroexcitatory amino acids (NEA), suggesting that some PF components cross the blood-brain barrier, the same as NEA. However, the HPLC and mass spectrometric analysis did not show the presence of the known neuroexcitatory amino acids, kainic acid, domoic acid and NMDA. We conclude that G. marginata possess substances with neurotoxic and lethal activities.