Studies of expression and mechanism of free-radical associated products in neuromuscular disorders.

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The aim of this study is to clarify the expression and mechanism of free-radical associated products in neuromuscular disorders.Hyperglycemia exacerbates the effect of ischemia-reperfusion on peripheral nerve in rat. After a 2-hour ischemia and 24-hour reperfusion of sciatic nerves of rats, the concentrations of lipid peroxide and loose myelin in the nerves were significantly increased in the diabetic rats, but not in the nondiabetic rats. Loose myelin may be increased as a result of the effects of oxygen free radicals produced by ischemia-reperfusion, which are exacerbated by hyperglycemia.On ragged -red fibers in mitochondria! Encephalomyopathies, Mn-SOD, ec-NOS, nitrotyrosine were strongly stained by immunohistochemistry. And then, Fas, Fas-ligand, caspase 3, caspase 9, Bax, Apaf-1 and bcl-2 were also immunostained on ragged-red fibers. Therefore, The free-radical injury may induce apoptosis in the ragged-red fibers of mitochondrial encephalomyopathies.In inclusion body myositis and rimmed-vacuole type distal myopathy, Fas was highly expressed in fibers with vacuole. The pathomechanism of the diseases may be involved of apoptosis associated with Fas. In polymyositis, however, Fas was not expressed. On the other hand, in dermatomyositis tenacin was stained in the network pattern in the interstitial areas. Tenacin also showed perifascicular atrophy. Tenacin is a very useful marker for diagnosis of dermatomyositis.The expression of dystrophin, α-sarcoglycan, β-dystropglycan, α1-syntrophin, and nNOS were evaluated in regeneration skeletal mucles of rats after cardiotoxin-induced myonecrosis. The regeneration advances from the basement menbrane side to the subsarcolemmal side and from the proteins associated with structure of the basement membrane to the proteins associated with signal transmitting. The expression of nNOS is related to the muscle fiber type differentiation, and the role of nNOS is related to the function of the type 2B fibers of the muscle.