ISSN:0148-639X    

DOI:10.1002/mus.880110702

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

年代:1988

数据来源: WILEY

摘要:

AbstractMyology has greatly benefited from the recent unification of concepts in molecular, cellular, and developmental biology. The interplay between intrinsic and extrensic factors in determining the physiologic characteristics of individual myofibers has emerged as an important theme. Of special note is the manner in which the study of contractile protein gene structure and expression has contributed to our understanding of the development and ultimate plasticity of the contractile apparatus. As mechanistic models of normal myogenesis achieve increasing sophistication, the opportunities for understanding the pathogenesis of progressive muscle disfunction improve. In this article we review recent progress in basic myology which will be of interest to clinicians studying the heritable neuromuscular disorders.

ISSN:0148-639X    

DOI:10.1002/mus.880110703

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe contribution of “reverse genetic” strategies to neuromuscular disease research is evident in the progression of breakthroughs that have recently culminated in the cloning of the Duchenne muscular dystrophy (DMD) cDNA. The resultant improvements in our understanding of the genetic basis of Becker muscular dystrophy (BMD) and DMD serve as models for similar investigation of other heritable disorders. These genetic advances have outpaced concurrent work on the molecular pathogenesis of the dystrophic process, with the curious result that inferences about the DMD protein's amino acid sequence have preceded any information about its function or intracellular localization. In recognition that this foundation sets the stage for the rapid elucidation of the disease's pathogenesis, we review the experimental basis of such advances, with reference to relevant progress in basic myology, pathology, and molecular biology. We conclude with a view towards the ultimate clinical implications of these experimental break‐thr

ISSN:0148-639X    

DOI:10.1002/mus.880110704

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

年代:1988

数据来源: WILEY

摘要:

AbstractStimulation of the second (S1) or third (S2) digit elicits a median sensory potential at the wrist. Similarly, a shock applied to the median (Sm) or ulnar (Su) nerve at the wrist evokes a sensory potential of the fourth digit and a muscle potential over the thenar eminence. Hence, a concomitant application of S1and S2orSmandSuwith varying interstimulus intervals simulates the effect of desynchronized inputs. In 10 hands, a shift in latency on the order of 1 msec between S1and S2orSmandSucaused a major reduction in sensory potential by as much as 30–40% but little change in muscle action potential. A latency difference slightly less than one‐half the total duration of unit discharge maximized the phase cancellation between the two components and consequently the loss of area under the wave

ISSN:0148-639X    

DOI:10.1002/mus.880110705

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to examine the effects of glucocorticoid treatment on the contractile, electrical and fatigue properties of isolated motor units of identified type. Although it is known that glucocorticoid administration induces atrophy and weakness most strongly in fast, pale muscles and to a lesser extent in red muscle, the relationship between steroid effects and motor unit type is not known. Properties of medial gastrocnemious (MG) and soleus (SOL) motor units were studied in normal cats and in cats treated with triamcinolone acetonide (3–4 mg/kg body weight for 10–16 days). Glucocorticoid treatment produced weakness preferentially in fast‐twitch motor units. This suggests that catabolic steroids cause a reduction in the amount of contractile protein and hence contractile strength of motor units in inverse proportion to their relative activity or degree o

ISSN:0148-639X    

DOI:10.1002/mus.880110706

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

年代:1988

数据来源: WILEY

摘要:

AbstractFatigue from high frequency stimulation is associated with EMG signal changes, which are primarily due to a slowing of the sarcolemma conduction velocity. In the present study, in which isolated mouse soleus and extensor digitorum longus muscles have been studied, it is shown that the action potential propagation velocity is (1) decreased by an increased extracellular potassium concentration, (2) independent of extracellular pH, (3) decreased by low intracellular pH, and (4) nearly independent of moderate changes in the sodium gradient. The EDL muscle is more affected than the soleus muscle. The ion effects on propagation velocity are seen within the physiological ranges. The propagation velocity was decreased after 2 min of electrical stimulation and recovered with a time course similar to the pH recovery. The effects of extracellular potassium and internal pH are due to independent mechanisms.

ISSN:0148-639X    

DOI:10.1002/mus.880110707

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

年代:1988

数据来源: WILEY

摘要:

AbstractL‐carnitine stimulated CO2production from 1‐14C pyruvate in mitochondria from human skeletal muscle nearly twofold. A comparable increase in the pyruvate dehydrogenase complex (PDHC) activity was seen. Moreover, in the presence of L‐carnitine and at pyruvate concentration greater than 0.25 mM, this effect was associated with a marked increase of acetylcarnitine synthesis. Deoxycarnitine, an inhibitor of carnitine acetyltransfersase (CAT), partially reversed the effect of carnitine on PDHC activity. The stimulatory effect of carnitine on PDHC activity in human mitochondria is mediated by the modulation of the intramitochondrial acetylCoA/CoASH

ISSN:0148-639X    

DOI:10.1002/mus.880110708

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

年代:1988

数据来源: WILEY

摘要:

AbstractAlthough a substantial literature confirms the abnormal flow properties of diabetic blood, only in a few papers has the vasculitis of diabetic neuropathy been considered to have a hemorheological cause. It is proposed that the pathogenesis of nerve lesions involves an interaction between the specialized nerve vascular system and focal ischemic lesions resulting from rheologically induced stasis. The proposition is extended into other conditions with abnormal blood rheology such as hypothyroidism, uremia, dysglobulinemia, polyarteritis nodosa, and lepromatous leprosy. It is concluded that the treatment of such polyneuropathies should include an agent which would improve the flow properties of the blood.

ISSN:0148-639X    

DOI:10.1002/mus.880110709

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn rabbits, 9 g rectus femoris (RFM) muscles were grafted with tendon repair and with (1) nerves and blood vessels intact, (2) nerves intact and blood vessels anastomosed, or (3) nerves and blood vessels anastomosed. The influences of tendon, nerve, and vascular repair on the functional capabilities of grafts were compared 15–120 days after grafting. Data were collected on the mass, total protein content, oxidative capacity, maximum force development, and fatigability of grafts and control RFM muscles. When stabilized 90–120 days after grafting, mean values for the three types of grafts were not significantly different. Compared with values for control RFM muscles, each type of graft had significantly lower mean values for mass, total protein content, and maximum force, but the grafts were more resistant to fatigue. In RFM grafts, nerve and vascular repair do not contribute significantly to the impairments. Consequently, tendon repair appears to be responsible for the major functional defic

ISSN:0148-639X    

DOI:10.1002/mus.880110710

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe influence of glucocorticoids on muscle glutamine production in starvation was studied by using cortisol‐treated or non‐cortisol‐treated, starved, adrenalectomized rats. Administration of cortisol at physiological doses in vivo (1 mg/100 g body weight) to fasted, adrenalectomized rats increased the muscle ratio of glutamine/glutamate and the activity of glutamine synthetase after only 6 hours. Prior treatment of fasted, adrenalectomized animals with actinomycin D or proglavine abolished these increases by cortisol. Therefore, cortisol induces muscle glutamine synthetase, and this induction can be detected by changes in the fresh‐muscle ratio of glutamine/glutamate. Using this ratio as a qualitative indicator of muscle glutamine synthesis, the role of glucocorticoids in modifying muscle glutamine production in starvation was studied. In fresh‐frozen soleus, extensor digitorum longus, and diaphragm muscle, starvation led to greater ratios of glutamine/glutamate and higher levels of tyrosine, which are indicative of enhanced muscle protein turnover. These effects were not apparent in starved, adrenalectomized animals but were restored, at least partially, by administering a physiological dose of cortisol. Therefore, glucocorticoids seem essential for promoting muscle glutamine production in starvation probably by inducing the activity of glutamine s

ISSN:0148-639X    

DOI:10.1002/mus.880110711

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

年代:1988

数据来源: WILEY