Morphometric study of skeletal muscle ultrastructure

Engel, Andrew G.; Santa, T; Stonnington, Henry H.; Jerusalem, Felix; Tsujihata, Mitsuhiro; Brownell, A. Keith W.; Sakakibara, Hiroyoshi; Banker, Betty Q.; Sahashi, Kentaro; Lambert, Ellen

doi:10.1002/mus.880020312

Cited by 12 publications

(7 citation statements)

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“…Engel et al (1979) reported a lipid fraction of 0.12_+0.02% for normal fibres, whereas a value of 10.4 _+ 1.28% was found in a case of carnitine deficiency, Angelini et al (1976) also mentioned the presence of "glycogen fields" in the muscle cells after carnitine treatment, just as we found in our patient.…”

Section: Discussioncontrasting

confidence: 39%

Successful carnitine treatment in a non-carnitine-deficient lipid storage myopathy

et al. 1980

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An 18-month-old boy presented with general hypotonia, decreased muscle strength, retarded motor development and stunted growth. The excretion of dicarboxylic acids was enhanced. EMG was normal. A muscle biopsy revealed a lipid storage myopathy. Oral daily supplementation with 2 g D, L-carnitine resulted in: (1) an increase of the growth velocity; (2) increased muscle strength, and (3) a decrease in the lipid fraction of the fibre volume. The carnitine content of the muscle biopsied prior to treatment appeared to be normal.

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Section: Discussioncontrasting

confidence: 39%

Successful carnitine treatment in a non-carnitine-deficient lipid storage myopathy

et al. 1980

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“…GALVAS et al (1982) classified individual fibres of the cat flexor carpi radialis muscle using histochemistry and assessed the same fibres using electron micro:' scopy. The Z-line width in human muscles increases continuously with mitochondrial content (JERUSALEM et al 1975;ENGEL et al 1979;PRINCE et al 1981;SJOSTROM et al 1982a). There was wide overlap betwen the fibre types with respect to mitochondrial volume, volume of lipid droplets, amount of reticulum and T -system membranes, and Z-line width.…”

Section: Fibre Types and Electron Microscopymentioning

confidence: 97%

Skeletal Muscle

Schmalbruch

1985

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“…These findings suggest that the mutant enzyme would be most vulnerable to inhibition when it is most needed, i. e. when fatty metabolism is stressed. This in turn, could readily explain why the symptoms of CPT 'deficiency' are intermittent, why they differ from those of muscle carnitine deficiency [57], and why so much less lipid accumulates in muscle in CPT than in carnitine deficiency [58].…”

Section: Physiological Consequencesmentioning

confidence: 99%

Regulatory properties of a mutant carnitine palmitoyltransferase in human skeletal muscle

Zierz

Engel

1985

Eur J Biochem

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Carnitine palmitoyltransferase (EC 2.3.1.21) was studied in sonicated muscle homogenates of seven patients who had recurrent attacks of myoglobinuria and marked deficiency of carnitine palmitoyltransferase in the isotope exchange assay, and in control subjects.1. When L-palmitoylcarnitine was reduced from 0.5 mM to 0.05 mM in the isotope exchange assay, enzyme activity returned to normal in the patients but was not significantly altered in the controls.2. When the forward assay was performed in the presence of 80 pM palmitoyl-CoA and 0.1 % albumin, all patients showed normal carnitine palmitoyltransferase activity. The apparent K,,, values for DL-carnitine and palmitoyl-CoA were also normal in the patients.3. When albumin was omitted from the forward assay, 72-105% of the initial activity was observed in the controls, but only 31 -55% in the patients.4. When the palmitoyl-CoA concentration in the forward assay exceeded 0.08 mM the enzyme activity was inhibited in both patients and controls, but the inhibition was significantly greater in the patients.5. The addition of either L-palmitoylcarnitine or DL-palmitoylcarnitine to the forward assay progressively inhibited enzyme activity in both patients and controls, but the inhibition was significantly greater in the patients. In the controls but not the patients D-palmitoylcarnitine was less inhibitory than the L-isomer or the m-racemate.6. When the forward assay was performed with muscle homogenates preincubated with 0.4% Triton X-100 only 7 -21 % of the original enzyme activity remained in the patients, but 86 -110% was found in the controls.7. Increasing concentrations of malonyl-CoA inhibited both the forward and the isotope exchange assays. When the inhibition was maximal, only 14-18% of the CPT activity remained in homogenates of patients but 32-47% in homogenates of controls. The Zs0 (median inhibitory concentration) and Ki values for malonyl-CoA determined in the forward assay were not significantly different in the patients and controls.The data imply that CPT deficiency is caused by altered regulatory properties of a mutant enzyme and/or by altered interaction between the enzyme and its membranous environment rather than lack of catalytically active CPT I, I1 or both. The mutant CPT would be most vulnerable to inhibition by its substrate and/or product when lipid metabolism is stressed. This could also explain why the symptoms differ from muscle carnitine deficiency, and why so little lipid accumulates in muscle in CPT deficiency.Exercise-induced episodes of muscle weakness, pain, rhabdomyolysis and myoglobinuria with or without renal failure have been reported in patients with skeletal muscle CPT deficiency.Since the original description of the disease by DiMauro and DiMauro in 1973 [l] 25 additional cases have been reported [2-211. Depending on the assay system used, CPT activities in the patients ranged from 'not detectable' [l, 2, 8, 101 to 20 -30% of normal [4,11,15, 201. 'Partial deficiencies' in which 45 -60% of normal CPT activity was present also ...

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Morphometric study of skeletal muscle ultrastructure

Cited by 12 publications

References 0 publications

Successful carnitine treatment in a non-carnitine-deficient lipid storage myopathy

Successful carnitine treatment in a non-carnitine-deficient lipid storage myopathy

Skeletal Muscle

Regulatory properties of a mutant carnitine palmitoyltransferase in human skeletal muscle

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