Biochemical Study of Muscle in Progressive Muscular Dystrophy 1

Abstract

Current concepts of progressive muscular dystrophy hold that it is a disease in which, through genetic error, there are intrinsic defects in muscle metabolism, although the nature of these hypothetical defects remains unrecognized. It is the purpose of this report to describe one approach to the problem and to show that there are defects in the metabolism of isolated muscle from patients with progressive muscular dystrophy. In addition, establishment of non-collagen nitrogen as a reference base provided an opportunity to repeat previous observations on the non-heminic iron content of muscle. Earlier work from this laboratory (5, 6) showed that non-heminic iron (that is, iron not included in chromoproteins, myoglobin, and the cytochromes) occurred in muscle in two varieties; one extractable by reducing agents, the second apparently linked with myosin (7). It had been found that the extractable iron in muscle from dystrophic patients was low in terms either of wet weight of muscle or of fat-free dry weight (8-10).Biopsies of muscle were obtained under general anesthesia. The samples were frozen at once in liquid nitrogen and analyses were performed without delay. Biopsies from patients without muscular dystrophy, controls, were obtained from the right transversus abdominis during operation for appendicitis. Biopsies from patients with muscular dystrophy were obtained from the left transversus abdominis. After freezing the muscle, an aqueous extract was prepared in the Potter-Elvebjem homogenizer held at the temperature of melting ice. The extracting medium was 20 volumes of 0.1 N sodium fluoride. Aliquots were analyzed for non-collagen nitrogen (11), for total nitrogen, for aldolase concurrently by the method of Dounce, Beyer, and Barnett (12,13) and by the method of Sibley and Lehninger (4), and for phosphorylase by the Coris' method (3). In addition, in a number of patients the activity of aldolase in serum was also assessed (14). In three patients interpretation of values for non-collagen nitrogen were checked by determination of collagen and elastin (scleroproteins) by the method of Neumann and Logan (15). Extractable iron was determined colorimetrically with orthophenanthroline, using sodium dithionine as a reducing agent (16).For phosphorylase assay the homogenate was centrifuged, the supernatant extract diluted with two volumes of a mixture of cysteine and NaF, pH 6.0, and left for two minutes at 38°. One-tenth ml. was used for the assay. Final concentration of cysteine was 0.05 M, pH 6.0. For aldolase assay the 1/20 extract was diluted with four volumes of water. Two-tenths ml. were used in the presence of 0.5 ml. 0.01 M fructose diphosphate, hydrazine and collidine buffer pH 7.5. RESULTSIn Table I, collagen nitrogen is expressed as per cent of total nitrogen in the biopsy specimen. There was a definite increase in collagen nitrogen 794

Chronic Progressive Myopathy With Myoglobinuria: Demonstration of a Glycogenolytic Defect in the Muscle*

“…Addition of epinephrine (26,43) or adenylic acid (25,26) to the incubation mixture or preincubation of tissue with epinephrine failed to activate the enzyme system. On the other hand, muscle preparations obtained from control individuals showed phosphorylase activity comparable in magnitude to that reported in earlier studies (44 ., %-" U I LIL; 3.y 1-1 I X ll"llictol ..INCILL11J..-.…”

Abnormalities of lipoprotein and carbohydrate metabolism in degenerative diseases of the nervous system - Motor neuron disease and spinocerebellar degeneration.

“…also are frequently associated with a wide variety of neurologic and neuromuscular disorders most of which involve muscle wasting : Parkinson's disease (Boyd et al 1.971;Van Woert and Mueller 1971;Lipman et al 1974; National Diabetes Data Group 1979), Huntington's chorea (Podolsky et al 1972), muscular dystrophy (Dreyfus et al 1954;Danowski et al 1956;Ionaescu and Luca 1963), myotonic dystrophy (Nadler et al 1950;Jacobson et al 1955;Marshall 1959;Caughey and Saucier 1962;Lee and Hughes 1964), chronic peripheral neuropathy (Collis and Engel 1968), late onset proximal myopathy (Collis and Engel 1968), cerebrovascular disease (Jakobson X967;Gertler et al 1972), Friedreich's ataxia (Podolsky et al 1964;Hewer and Robinson 1968;Podolsky and Sheremata 1970;Podolsky 1975), and ataxia telangiectasia (Barlow et al 1965). However, very little is known about glucose metabolism in other forms of spinocerebellar degeneration (SCD).…”

A Biochemical Study of Certain Skeletal Muscle Constituents in Human Progressive Muscular Dystrophy*

“…In human muscular dystrophy, the only previously reported metabolic alterations in enzyme activity have been decreases in overall glycogenolysis and in some individual enzymes of this system, including phosphorylase, phosphoglucomutase and aldolase (22,23). The results reported in this paper confirm the absolute decrease of glycolysis in muscular dystrophy but limit this alteration to cases classified here as juvenile dystrophy.…”