摘要:

AbstractAn electrophysiologic study of peripheral nerve excitability was performed in patients with hyperkalemic periodic paralysis (HPP) and in normal controls. It was found that a marked degree of neural hyperexcitability existed in all patients with HPP who showed cold sensitivity. The results suggest involvement of the nerve cell membrane in the proximal segments of peripheral nerve. This testing method may be of value in differentiating the cold‐sensitive variant of HP

ISSN:0148-639X    

DOI:10.1002/mus.880020402

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

年代:1979

数据来源: WILEY

摘要:

AbstractCell‐free and whole‐tissue protein synthesis was studied in skeletal muscle of untrained male guinea pigs that had undergone a treadmill run to exhaustion. Experiments using explants from the gastrocnemius muscle maintained in organ culture demonstrated that the ability of the acutely exercised muscle to incorporate amino acids into protein had increased. Compared to polyribosomes prepared from several lower hind limb muscles of nonexercised guinea pigs, polyribosomes from the same muscle in exhausted guinea pigs had incorporated almost 50% more radioactive leucine into protein. However, the polysome profiles of control and exercised muscle were identical, and no difference in the total polysome RNA content could be detected. The efficiency of in‐vitro protein synthesis using washed membrane‐bound polyribosomes (microsomes) isolated from acutely exercised skeletal muscle was 50% greater than with microsomes from rested control

ISSN:0148-639X    

DOI:10.1002/mus.880020403

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

年代:1979

数据来源: WILEY

摘要:

AbstractFive volunteer subjects held isometric handgrip contractions at specific submaximal tensions until the required tension could no longer be maintained. At the start of those contractions, the amplitude of the surface electromyogram (EMG) was linearly related to the tension exerted; the amplitude of the EMG increased linearly throughout these sustained contractions by a constant amount—about 30% of the maximum. During sustained contractions, brief, intermittent maximal efforts showed that strength declined linearly at all tensions. At 25% maximal voluntary contraction (MVC), there was a linear fall in the EMG amplitude associated with the brief maximal efforts, but the fall in strength was more rapid than the fall in EMG amplitude. At 70% MVC, there was no fall in the EMG amplitude in response to the brief maximal efforts, while the muscle strength fell linearl

ISSN:0148-639X    

DOI:10.1002/mus.880020404

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

年代:1979

数据来源: WILEY

摘要:

AbstractCorticosteroid myopathy was studied in young, mature New Zealand white rabbits given daily injections of betamethasone (0.3 mg/kg body weight/day) for two weeks. Control rabbits were pair‐fed and received saline injections. Betamethasone treatment caused significant wasting of type 2 gluteus medius and psoas muscles but did not cause any atrophy of type 1 soleus and gluteus minimus muscles. The Mg2+‐ and Ca2+‐activated myofibrillar ATPase activities of the corticosteroid‐treated rabbits did not differ from controls despite a 30% reduction in muscle wet weight and pronounced reduction in cross‐sectional area of fibers. SDS‐polyacrylamide gel electrophoresis profiles of myofibrillar proteins did not differ quantitatively or qualitatively between experimental and control rabbits. Studies of net muscle protein degradation (using3H‐leucine) in betamethasone‐treated and control rabbits indicate that both type 1 and type 2 muscle fiber proteins are degraded several times faster in the corticosteroid‐treated group. This suggests that a compensatory mechanism exists for those type 1 and mixed fiber type muscles which have increased degradation but do no

ISSN:0148-639X    

DOI:10.1002/mus.880020405

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

年代:1979

数据来源: WILEY

摘要:

AbstractIn an attempt to determine whether chronic glucocorticoid treatment affects speed‐ and strength‐related properties of fast‐twitch muscle and slow‐twitch muscle, in‐situ contractile properties of soleus and gastrocnemius muscles were measured in rats after 14 days on a regimen of triamcinolone acetonide injected at a dosage of 2 mg/kg/day. No effects on contractile speed or strength were noted for either muscle. The time to peak tension in soleus muscle was significantly longer in the treated group (43.0 ± 1.0 msec) than in the control group (38.7 ± 0.7 msec); however, this was attributed to a prolongation of “active state” duration, as suggested by the fact that treated muscles also showed significantly elevated twitch‐tetanus ratios. The treatment‐induced enhancement of the specific twitch tension was more pronounced in the gastrocnemius muscles (198% ± 19% of control) than in the soleus muscles (153% ± 9% of control). The difference in response to steroid treatment may reflect structural and functional difference in fast‐ and slow

ISSN:0148-639X    

DOI:10.1002/mus.880020406

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

年代:1979

数据来源: WILEY

摘要:

AbstractMuscle biopsies from two patients revealed that numerous type 2 fibers contained large abnormal areas filled with cylindrical spirals. The cytochemical profile of these cylindrical spirals was sufficiently characteristic that they could be distinguished from tubular aggregates. Their electron microscopic appearance was unmistakable. Their origin and significance are uncertain. The diverse nature of the patients' conditions (cramps and malignancy, and an unusual form of spinocerebellar degeneration) indicate that these abnormal structures are not disease specific.

ISSN:0148-639X    

DOI:10.1002/mus.880020407

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

年代:1979

数据来源: WILEY

摘要:

AbstractCardiomyopathic hamsters (UM‐X7.1 strain) have demonstrable myopathy involving both skeletal and cardiac muscle. In addition, they have multiple ocular abnormalities. In this study, extraocular muscles were examined by light and electron microscopy. Changes observed within affected muscle fibers were variable and included coagulation necrosis, lysis of myofibrils, mitochondrial changes, and infiltration by phagocytic cells. Regenerative changes included duplication of myoblast nuclei, proliferation of sarcoplasmic reticulum, and myofibrillogenesis. The lesions are presumably myogenic in origin. The cardiomyopathic hamster may be useful as an animal model for certain types of ocular myopathy in ma

ISSN:0148-639X    

DOI:10.1002/mus.880020408

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe case history of a patient with severe muscular weakness resulting from magnesium intoxication following oral and rectal administration of magnesium citrate cathartics is reported. The findings of the electrophysiologic studies were characteristic of the neuromuscular blockade seen in this disorder, including marked reduction in evoked muscle action potential amplitude which progressively declined on nerve stimulation at low rates, and a striking degree of facilitation of evoked muscle action potential after exercise or on high‐frequency stimulation. When the hypermagnesemia was corrected, strength returned to norma

ISSN:0148-639X    

DOI:10.1002/mus.880020409

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

年代:1979

数据来源: WILEY

摘要:

AbstractEdema and increased endoneurial fluid pressure developed in peripheral nerves of rats that received a diet containing 40% galactose during a study of the role of sugar alcohols in producing neuropathy. Fluid pressure was elevated starting in the third month and progressed to a fivefold increase over control values by the fifth month. Microscopic examination confirmed the presence of edema as predicted by the sorbitol theory, which is often invoked to explain the pathogenesis of diabetic neuropathy.

ISSN:0148-639X    

DOI:10.1002/mus.880020410

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

年代:1979

数据来源: WILEY

摘要:

AbstractFree grafts of the extensor digitorum longus (EDL) muscle of the rat are invaded by regenerating nerve fibers during the second postoperative week. Neuromuscular junctions are established during the third week. Levels of choline acetyltransferase (CAT) activity parallel the invasion of the graft by nerve fibers, but this activity never returns to control levels. We conclude that incomplete reinnervation of free muscle grafts may be a factor in the failure of such grafts to reattain the mass of control muscles.

ISSN:0148-639X    

DOI:10.1002/mus.880020411

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

年代:1979

数据来源: WILEY