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Query: UMLS:C0026850 (muscular dystrophy)
 5,870 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two children, born to related parents, presented since birth a muscular defect rapidly complicated by painful joint stiffness. The oldest child died at 6 months of age, from respiratory complications. The second-14 month old- does not sit without support. The muscle fibres are of unequal calibre and numerous fibres have under-sarcolemmal PAS positive areas contain glycogen, as seen on electron microscopy. In the second patient, the biochemical analysis showed a moderate glycogen accumulation and muscular enzymatic studies demonstrated an isolated and major deficiency in phosphofructokinase activity. Activity was normal in red blood cells and in fibroblasts cultured in vitro. Hence, these cases should be distinguished from formerly reported cases of phosphofructokinase deficiency. This type of P.F.K. deficiency should be looked for in patients with severe congenital muscular dystrophy and early joint involvement.
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PMID:[Familial congenital muscular dystrophy caused by phosphofructokinase deficiency]. 15 29

The study of skeletal muscle disorders is providing potentially important insights into regulatory mechanisms in human exercise and fatigue and information useful for diagnostic and treatment purposes. This review primarily concerned the general metabolic and physiological factors which set upper limits to performance of various types of exercise in patients with a variety of muscle disorders. From the standpoint of exercise performance, skeletal muscle diseases can be classified into three major groups. One group consists of primary disorders of muscle energy metabolism, including defects in muscle carbohydrate and lipid metabolism, disorders of mitochondrial electron transport, and abnormalities of purine nucleotide metabolism. Exercise performance largely reflects the capacity for ATP resynthesis. Oxidative phosphorylation is the dominant quantitative source of energy for ATP resynthesis under most exercise conditions. Consequently, patients with disordered oxidative metabolism (i.e., patients with defects in the availability or utilization of oxidizable substrate, such as those with phosphorylase or PFK deficiency or those with defects in mitochondrial electron transport) typically demonstrate severely impaired exercise performance. Intolerance to sustained exercise and premature fatigability are salient features of muscle oxidative disorders. Maximal oxygen uptake and maximal a-v O2 difference are markedly subnormal related to an attenuated muscle oxygen extraction. Muscle weakness and atrophy are less common. Anaerobic muscle performance is dramatically limited in patients with virtually complete defects of glycogenolysis/glycolysis but appears relatively normal in those with electron transport defects. A second major group of disorders includes patients with decreased muscle mass due to muscle necrosis, atrophy, and replacement of muscle by fat and connective tissue. These disorders are exemplified by the various muscular dystrophies (Duchenne's dystrophy, Becker's dystrophy, LG dystrophy, FSH dystrophy, and myotonic dystrophy) in which exercise performance is severely impaired due to muscle wasting and weakness in spite of largely normal pathways for muscle ATP resynthesis. In muscular dystrophy patients, the degree to which maximal oxygen uptake and anaerobic muscle performance are impaired appears to be a function of the severity of muscle weakness and atrophy. A third group of disorders includes patients with impaired activation of muscle contraction or relaxation. These disorders may be considered in two subcategories. In the first, impaired activation or relaxation of contractile activity is due to intrinsic muscle dysfunction (e.g., diseases associated with myotonia or periodic paralysis). In the second subcategory, there is impaired muscle activation due to a primary abnormality in the central nervous system, motor nerves, or neuromuscular junction.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Skeletal muscle disorders and associated factors that limit exercise performance. 267 57

Evidence to suggest the presence of abnormal metabolism of oxygen free radicals in progressive muscular dystrophy is presented using an animal model. In the superficial pectoral muscles of dystrophic chickens, enzyme activities regulating the metabolism of oxygen free radicals, i.e., catalase, superoxide dismutases and glutathione peroxidase, were significantly elevated within 1 week of hatching. Activities of related enzymes, i.e., glutathione reductase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase were also elevated. In contrast, the specific activity of phosphofructokinase, the rate-limiting enzyme of the glycolytic pathway, was normal during the first 4-week period. These results suggest that there is an increased turnover of oxygen free radicals in the dystrophic muscle. This concept appears important in a further investigation of the pathogenesis and treatment of progressive muscular dystrophies.
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PMID:Pathogenesis of progressive muscular dystrophy: studies on free radical metabolism in an animal model. 336 52

Injection of serotonin (5-hydroxytryptamine) induced a marked decrease in the level of glucose 1,6-diphosphate (Glc-1,6-P2) in the rat tibialis anterior muscle. Concomitant to the decrease in Glc-1,6-P2, the potent activator of phosphofructokinase and phosphoglucomutase, the activities of both these enzymes were markedly reduced by serotonin. The level of Glc-1,6-P2 and the activities of phosphofructokinase and phosphoglucomutase increased with age in the tibialis anterior muscle and the effect of serotonin was more pronounced in the older animals. Serotonin also induced a significant increase in the level of cyclic GMP in muscle. The serotonin-induced changes in the normal muscle mimic the changes in carbohydrate metabolism we found previously in muscular dystrophy.
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PMID:Changes in the levels of glucose 1,6-diphosphate and cyclic GMP, and in the activities of phosphofructokinase and phosphoglucomutase induced by serotonin in muscle. 630 80