摘要:

AbstractAt rest and during sustained exercise, lipids are the main source of energy for muscle. Free fatty acids become available to muscle from plasma free fatty acids and triglycerides, and from intracellular triglyceride lipid droplets. Transport of long‐chain fatty acyl groups into the mitochondria requires esterification and de‐esterification with carnitine by the “twin” enzymes carnitine palmityltransferase (CPT) I and II, bound to the outer and inner faces of the inner mitochondrial membrane. Carnitine deficiency occurs in two clinical syndromes. (1) In themyopathicform, there is weakness; muscle biopsy shows excessive accumulation of lipid droplets; and the carnitine concentration is markedly decreased in muscle but normal in plasma. (2) In thesystemicform, there are weakness and recurrent episodes of hepatic encephalopathy; muscle biopsy shows lipid storage; and the carnitine concentration is decreased in muscle, liver, and plasma. The etiology of carnitine deficiency is not known in either the myopathic or the systemic form, but administration of carnitine or corticosteroids has been beneficial in some patients. “Secondary” carnitine deficiency may occur in patients with malnutrition, liver disease, chronic hemodialysis, and, possibly, mitochondrial disorders. CPT deficiency causes recurrent myoglobinuria, usually precipitated by prolonged exercise or fasting. Muscle biopsy may be normal or show varying degrees of lipid storage. Genetic transmission is probably autosomal recessive, but the great male predominance (20/21) remains unexplained. In many cases, lipid storage myopathy is not accompanied by carnitine or CPT deficiency, and the biochemical error remains to be

ISSN:0148-639X    

DOI:10.1002/mus.880030502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractTwelve children who had developed Kugelberg‐Welander (K‐W) spinal muscular atrophy (SMA) before the age of six years were investigated. Electrophysiological, histochemical, ultrastructural, and biochemical studies demonstrated features of immature muscle fibers suggesting a fetal defect as in the Werdnig‐Hoffmann (W‐H) form of SMA. Comparison with known patterns of human myogenesis and of experimental denervation of immature muscle suggested that the defect in K‐W SMA probably takes place in fetal life at a stage later than in W‐H SMA. In contrast to W‐H SMA, a considerable percentage of mature fibers of normal structure and diameter were present. The immature fibers impair the normal development of muscle cells by preventing the increase in number of mature fibers and causing an overloading of the normal fibers with consequent hypertrophy and eventually destructive changes. This is the pattern in K‐W disease that distinguishes the juvenile form of SMA f

ISSN:0148-639X    

DOI:10.1002/mus.880030503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractClinical, electrodiagnostic, and morphological studies were performed on three patients with localized hypertrophic neuropathy (LHN). LHN is characterized clinically by slowly progressive motor mononeuropathy without significant pain or numbness. Nerve conduction studies and needle electrode examination show severe focal motor and sensory axonal loss. Morphological findings in the localized areas of enlarged nerves are different from those of generalized hypertrophic neuropathy, entrapment neuropathy, and neurofibroma, and consist of primary perineurial cell hyperplasia. The tumor is thus a perineurioma. This rare tumor can occur both in generalized neurofibromatosis and in isolated form and appears to be the cause of localized hypertrophic neuropathy.

ISSN:0148-639X    

DOI:10.1002/mus.880030504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe medical belly of the gastrocnemius and the extensor digitorum longus muscles of rats were tenotomized. One day following tenotomy, the mean sarcomere length of the fast medial gastrocnemius was 1.8 μm, a value comparable to that of tenotomized slow soleus. The mean sarcomere length of the tenotomized extensor digitorum longus, however, was 2.0 μm, a figure which differed significantly from the values obtained for both the soleus and the gastrocnemius. Histological preparations showed the presence of central core degeneration in slow fatigue‐resistant fibers of the tenotomized gastrocnemius comparable to that seen in the soleus. No changes were found in the fibers of the tenotomized extensor digitorum longus. The fact that central core lesions were produced in the fibers of soleus and medial gastrocnemius but not in the extensor digitorum longus may be related to the lesser reduction in sarcomere length following tenotomy of the latter mus

ISSN:0148-639X    

DOI:10.1002/mus.880030505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractSurface protein topographies of cultured normal and genetically dystrophic embryonic chick breast muscle cells and fibroblasts were compared by external labeling and size distribution analysis by sodium dodecyl sulfate‐polyacrylamide gradient slab gel electrophoresis. Four labeling techniques were evaluated and all were found to be specific for the cell surface. Using radioiodination of tyrosine residues and periodateborotritide labeling of sialic acid residues, no reproducible abnormalities could be detected in any of the dystrophic cell types—fibroblasts, fusion‐inhibited differentiated myoblasts, and multinucleated differentiated myotubes. However, comparison of 3‐day‐old cultures of normal fusion‐inhibited differentiated myoblasts with fused myotubes revealed that increased iodination of protein classes with nominal molecular weights of 230,000 and 88,000 was evident in the myoblasts. In addition, large structural differences were detected between differentiated myoblasts and myogenic cells grown in the presence of phorbol 12‐myristate 13‐acetate, a potent tumor promoter and reversible inhibitor of myogenic

ISSN:0148-639X    

DOI:10.1002/mus.880030506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe nerve conduction velocity along the whole length (knee to the spinal cord) of the 1a sensory and motor fibers of the tibial nerve, innervating the gastrocnemius and soleus muscles, of 29 control subjects and 32 patients with chronic renal failure was estimated with recently introduced electrophysiologic F‐wave and H‐reflex methods. In control subjects and in uremic patients, the proximal sensory (1a) nerve conduction velocity (SNCV) was faster than the proximal motor nerve conduction velocity (MNCV), a finding which is attributed to the larger diameter and therefore faster conduction properties of 1a fibers. In uremic patients, the proximal 1a SNCV and MNCV were significantly slowed in comparison with the values in control subjects, while the terminal M‐response latency was not significantly prol

ISSN:0148-639X    

DOI:10.1002/mus.880030507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880030508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880030509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880030510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880030512

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY