RESUMO
It has previously been shown that hyperoxia induces nonapoptotic cell death in cultured lung epithelial cells, whereas hydrogen peroxide (H(2)O(2)) and paraquat cause apoptosis. To test whether pathways leading to oxidative apoptosis in epithelial cells are sensitive to molecular O(2), A549 cells were exposed to 95% O(2) prior to exposure to lethal concentrations of H(2)O(2). The extent of H(2)O(2)-induced apoptosis was significantly reduced in cells preexposed to hyperoxia compared with room-air controls. Preexposure of the hyperoxia-resistant HeLa-80 cell line to 80% O(2) also inhibited oxidant-induced apoptosis, suggesting that this inhibition is not due to O(2) toxicity. Because hyperoxia generates reactive oxygen species and activates the redox-sensitive transcription factor nuclear factor kappa B (NF-kappa B), the role of antioxidant enzymes and NF-kappa B were examined in this inhibitory process. The onset of inhibition appeared to be directly related to the degradation of I kappa B and subsequent activation of NF-kappa B (either by hyperoxia or TNF-alpha), whereas no significant up-regulation of endogenous antioxidant enzyme activities was found. In addition, suppression of NF-kappa B activities by transfecting A549 cells with a dominant-negative mutant construct of I kappa B significantly augmented the extent of H(2)O(2)-induced apoptosis. These data suggest that hyperoxia inhibits oxidant-induced apoptosis and that this inhibition is mediated by NF-kappa B.
Assuntos
Apoptose/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Pulmão/citologia , Pulmão/efeitos dos fármacos , Oxidantes/antagonistas & inibidores , Oxigênio/farmacologia , Antioxidantes/metabolismo , Grupo dos Citocromos c/metabolismo , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Citometria de Fluxo , Imunofluorescência , Humanos , Peróxido de Hidrogênio/antagonistas & inibidores , Peróxido de Hidrogênio/farmacologia , Quinase I-kappa B , Marcação In Situ das Extremidades Cortadas , Pulmão/metabolismo , NF-kappa B/metabolismo , Oxidantes/farmacologia , Oxigênio/toxicidade , Paraquat/antagonistas & inibidores , Paraquat/farmacologia , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/farmacologia , Regulação para Cima/efeitos dos fármacos , Xantina Oxidase/metabolismoRESUMO
BACKGROUND: Many practitioners involved with the cosmetic applications of botulinum toxin believe that electromyography (EMG) is an invaluable tool in determining the precise locations to inject. Others feel that it is unnecessary and of no value whatsoever. OBJECTIVES: The objective of this paper is to (1) demonstrate the proper technique for usage of the EMG machine, and (2) determine if its use in connection with injection of facial muscles for cosmetic purposes is worthwhile. CONCLUSIONS: The anatomy of the muscles of the face is somewhat variable from person to person. Electromyography can be a valuable adjunct when injecting botulinum toxin for cosmetic purposes by ensuring that the injecting needle is precisely in the muscle, thereby ensuring that the botulinum toxin will have the greatest possible effect.
