Impaired neuromuscular function by conjoint actions of organophosphorus insecticide metabolites omethoate and cyclohexanol with implications for treatment of respiratory failure.

BACKGROUND: Ingestion of agricultural organophosphorus insecticides is a significant cause of death in rural Asia. Patients often show acute respiratory failure and/or delayed, unexplained signs of neuromuscular paralysis, sometimes diagnosed as "Intermediate Syndrome". We tested the hypothesis that omethoate and cyclohexanol, circulating metabolites of one agricultural formulation, cause muscle weakness and paralysis. METHODS: Acetylcholinesterase activity of insecticide components and metabolites was measured using purified enzyme from eel electroplaque or muscle homogenates. Mechanomyographic recording of pelvic limb responses to nerve stimulation was made in anaesthetized pigs and isometric force was recorded from isolated nerve-muscle preparations from mice. Omethoate and cyclohexanol were administered intravenously or added to physiological saline bathing isolated muscle. We also assessed the effect of MgSO4 and cooling on neuromuscular function. RESULTS: Omethoate caused tetanic fade in pig muscles and long-lasting contractions of the motor innervation zone in mouse muscle. Both effects were mitigated, either by i.v. administration of MgSO4 in vivo or by adding 5 mM Mg2+ to the medium bathing isolated preparations. Combination of omethoate and cyclohexanol initially potentiated muscle contractions but then rapidly blocked them. Cyclohexanol alone caused fade and block of muscle contractions in pigs and in isolated preparations. Similar effects were observed ex vivo with cyclohexanone and xylene. Cyclohexanol-induced neuromuscular block was temperature-sensitive and rapidly reversible. CONCLUSIONS: The data indicate a crucial role for organophosphorus and solvent metabolites in muscle weakness following ingestion of agricultural OP insecticide formulations. The metabolites omethoate and cyclohexanol acted conjointly to impair neuromuscular function but their effects were mitigated by elevating extracellular Mg2+ and decreasing core temperature, respectively. Clinical studies of MgSO4 therapy and targeted temperature management in insecticide-poisoned patients are required to determine whether they may be effective adjuncts to treatment.

Disasters, Queer Narratives, and the News: How Are LGBTI Disaster Experiences Reported by the Mainstream and LGBTI Media?

The media plays a significant role in constructing the public meanings of disasters and influencing disaster management policy. In this article, we investigate how the mainstream and LGBTI media reported-or failed to report-the experiences of lesbian, gay, bisexual, transgender, and intersex (LGBTI) populations during disasters in Brisbane, Australia and Christchurch, New Zealand. The implications of our work lie within recent disasters research suggesting that marginalized populations-including LGBTI peoples-may experience a range of specific vulnerabilities during disasters on the basis of their social marginality. In this article, we argue that LGBTI experiences were largely absent from mainstream media reporting of the Brisbane floods and Christchurch earthquake of 2011. Media produced by and about the LGBTI community did take steps to redress this imbalance, although with uneven results in terms of inclusivity across that community. We conclude by raising the possibility that the exclusion or absence of queer disaster narratives may contribute to marginality through the media's construction of disasters as experienced exclusively by heterosexual family groups.