Enzyme Studies in Muscular Dystrophy VI

Weinstock, I.M.; Lukacs, M.

doi:10.1159/000457981

Cited by 19 publications

(4 citation statements)

References 14 publications

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“…Embryonic actin and myosin also contain less 3-methylhistidine (Trayer et al, 1968;Krzysik et al, 1971). This finding supports the hypothesis that hereditary muscular dystrophy in the chicken represents a delay or defect in the normal maturation and development of muscle (Morgan & Herrmann, 1965;Weinstock & Lukacs, 1965;Cosmos, 1970).…”

Section: Discussionsupporting

confidence: 73%

Myofibrillar protein degradation in the chicken 3-Methylhistidine release in vivo and in vitro in normal and genetically muscular-dystrophic chickens

Hillgartner

Williams

Flanders

et al. 1981

Biochemical Journal

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Myofibrillar protein degradation was measured in 4-week-old normal (line 412) and genetically muscular-dystrophic (line 413) New Hampshire chickens by monitoring the rates of 3-methylhistidine excretion in vivo and in vitro. A method of perfusing breast and wing muscles was developed and the rate of 3-methylhistidine release in vitro was measured between 30 and 90min of perfusion. During this perfusion period, 3-methylhistidine release from the muscle preparation was linear, indicating that changes in 3-methylhistidine concentration of the perfusate were the result of myofibrillar protein degradation. Furthermore, the viability of the perfused muscle was maintained during this interval. After 60min of perfusion, ATP, ADP and creatine phosphate concentrations in pectoral muscle were similar to muscle freeze-clamped in vivo. Rates of glucose uptake and lactate production were constant during the perfusion. In dystrophic-muscle preparations, the rate of 3-methylhistidine release in vitro (nmol/h per g of dried muscle) was elevated 2-fold when compared with that in normal muscle. From these data the fractional degradation rates of myofibrillar protein in normal and dystrophic pectoral muscle were calculated to be 12 and 24% respectively. Daily 3-methylhistidine excretion (nmol/day per g body wt.) in vivo was elevated 1.35-fold in dystrophic chickens. Additional studies revealed that the anti-dystrophic drugs diphenylhydantoin and methylsergide, which improve righting ability of dystrophic chickens, did not alter 3-methylhistidine release in vitro. This result implies that changes in myofibrillar protein turnover are not the primary lesion in avian muscular dystrophy. From tissue amino acid analysis, the myofibrillar 3-methylhistidine content per g dry weight of muscle was similar in normal and dystrophic pectoral muscle. More than 96% of the 3-methylhistidine present in pectoral muscle was associated with the myofibrillar fraction. Dystrophic myofibrillar protein contained significantly less 3-methylhistidine (nmol/g of myofibrillar protein) than protein from normal muscle. This observation supports the hypothesis that there may be a block in the biochemical maturation and development of dystrophic muscle after hatching. Free 3-methylhistidine (nmol/g wet wt.) was elevated in dystrophic muscle, whereas blood 3-methylhistidine concentrations were similar in both lines. In summary, the increased myofibrillar protein catabolism demonstrated in dystrophic pectoral muscle correlates with the increased lysosomal cathepsin activity in this tissue as reported by others.

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Section: Discussionsupporting

confidence: 73%

Myofibrillar protein degradation in the chicken 3-Methylhistidine release in vivo and in vitro in normal and genetically muscular-dystrophic chickens

Hillgartner

Williams

Flanders

et al. 1981

Biochemical Journal

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“…The protein content of the denervated muscle decreases as a result of augmented autolysis [7,19], proteolytic activity [13,33] and cathepsin activity [13,33,36]. The activities of glycolytic and Krebs cycle enzymes and adenosine triphosphate level were low [1].…”

mentioning

confidence: 99%

Aminotransferase Activity in Denervation Atrophy of the Amphibian Skeletal Muscle

Nb¹

1971

Enzyme

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The activity levels and some properties of aspartate aminotransferase and alanine aminotransferase of normal and denervated frog skeletal muscle were investigated. In general, the denervated muscle showed significant decrement in the activities of the two aminotransferases. But the peripheral nerve section did not induce any change in the aminotransferase levels of fiver, kidney, heart and serum of frog. In the skeletal muscle, the two aminotransferases were found to exist in two different isozymes, one being associated with the mitochondria and the other with the soluble fraction. The mitochondrial component of both the enzymes was relatively cationic in nature when compared to the soluble fraction. The denervated muscle showed a considerable decrease in both the isozymes of the two aminotransferases. The thermostability of both the enzymes was considerably lowered in the denervated muscle. No elevation of either aminotransferase activity was observed in the denervated skeletal muscle following addition of a heat-denatured serum, while a marked elevation was observed in the normal muscle. The enzymes of denervated muscle showed altered sensitivities towards their inhibitors. The results of the present study suggest that denervation induces quantitative as well as qualitative changes in the aminotransferases of frog skeletal muscle.

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“…information concerning the events ,associated with atrophy of the muscles (2,11,26,28) ; several lines of ations in the fibered muscles the disorder in 30). evidence suggest that alterdevelopment of the whiteare involved in the onset of the young chick (6,7,12,25, There have been few investigations into possible specific protein differences between normal and dystrophic tissues.…”

mentioning

confidence: 99%

“…For example, phosphorylase activity decreases (7), and oxygen consumption (28) , thymidine kinase (2 5 ) , and deoxyribonuclease activity (26) increases in dystrophic as compared to normal pectoral muscle. Many differences in the metabolism of the muscles become apparent shortly after the chicks hatch.…”

mentioning

confidence: 99%