Muscle Physiology in Healthy Men and Women and Those with Metabolic Myopathies

Normal muscle structure, growth, development, and regeneration

Knowledge about biochemical, structural and physiological aspects, and properties regarding the skeletal muscle has been widely obtained in the last decades. Muscle disorders, mainly represented in neuromuscular clinical practice by acquired and hereditary myopathies, are well-recognized and frequently diagnosed in practice. Most clinical complaints and biochemical characterizations of each myopathy depends on the appropriate knowledge and interpretation of pathological findings and their comparison with normal muscle findings. Great improvement has been obtained in the last decades mainly involving the mechanisms of normal muscle architecture and physiological function in the healthy individuals. Genetic mechanisms have also been widely studied. We provide an extensive literature review involving current knowledge regarding muscle cell structure and function and embryological and regenerative processes linked to muscle lesion. An updated comprehensive description involving the main nuclear genomic regulatory mechanisms of muscle regeneration and embryogenesis is provided in this review.

Evaluation of a mitochondrial disease criteria scoring system on mitochondrial encephalomyopathy in Chinese patients

Due to the complicated clinical features of mitochondrial encephalomyopathy, simplified mitochondrial disease criteria (MDC) have recently been established in Europe. This study evaluated the sensitivity and specificity of this scoring system in Chinese patients. Seventy-eight patients with suspected mitochondrial encephalomyopathy were recruited to be scored by the simplified MDC and were further classified into "possible" (2-4), "probable" (5-7), or "definite" categories (≥8). Significant differences were observed between the total scores in the mitochondrial encephalomyopathy group and the other myopathy group. In the mitochondrial encephalomyopathy group, 73.5% of patients had a score above 8, whereas in the other myopathy group, the "definite" percentage was only 3.2%, suggesting the proposed MDC scoring system has a high sensitivity for diagnosis of mitochondrial encephalomyopathy in China. Moreover, there were significant differences in the clinical scores and imaging portions of the MDC, suggesting that the simplified MDC may distinguish mitochondrial disorder from other multisystem disorders to aid in early diagnosis prior to a muscle biopsy.