摘要:

AbstractThe ability to measure spinal cord conduction velocity noninvasively is limited by available methodology. Surface recording of small spinal potentials, although feasible in infants and young children, is problematical in adults, especially when recording over the cervical spine. On the other hand, indirect methods designed to improve the signal‐to‐noise ratio, which include recording of somatosensory cortical evoked potentials, F‐waves, or other muscle responses, are limited by the unproven assumptions necessary in calculating spinal conduction. Additionally, each method has its own particular limitations. The majority of presently available noninvasive methods take a restricted, or no, account of conduction through the motor pathways. Despite these often serious limitations, each of the reviewed methods does play a useful clinical role in the electrophysiologic investigation of cord disease that is not visible radiologically. Knowledge of them allows for sufficient diversity to tackle most relevant problems until an ideal physiologic method is deve

ISSN:0148-639X    

DOI:10.1002/mus.880090202

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe motoneuron part of this review deals with the changes in recruitment and firing rates of the motor unit types upon changes from a physically inactive life to endurance or strength training. The muscle fibers react to prolonged exercise by adaptation to a higher level of performance. A matter of discussion is the prerequisites for a transformation between the basic muscle fiber types, slow twitch and fast twitch, during voluntary (transsynaptic) activity, which is demonstrated after artificial nerve stimulation. The review includes current knowledge of muscle fiber transformation as an adaptive response to increased usage either by electrical stimulation or by transsynaptic neuronal activity. The metabolic adaptation related to increased endurance is reviewed with special reference to effects on muscle fibers. The increase in strength as a result of high resistance training is mainly the result of increased muscle cross‐section. Whether this is solely the result of an increase in size of individual fibers or an increased fiber number is a controversial matte

ISSN:0148-639X    

DOI:10.1002/mus.880090203

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe have examined freeze‐fracture replicas and conventional thinsection images of rat myofibers prepared by perfusion and by conventional immersion fixation protocols, and myofibers of normal and dystrophic human myofibers prepared by similar immersion fixation methods. In both rat and human myofibers, the size and distribution of caveolae was found to differ substantially according to (1) the method of glutaraldehyde exposure, (2) the depth of the myofiber from the surface exposed to the fixative, and (3) if surgically bisected, the distance from the cut end of the myofiber. Conventional immersion fixation resulted in unavoidable but predictable alterations in sarcolemmal caveolae. These reproducible artifacts of fixation technique substantially complicate the use of caveolae as reliable markers for the characterization of human neuromuscular diseas

ISSN:0148-639X    

DOI:10.1002/mus.880090204

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

年代:1986

数据来源: WILEY

摘要:

AbstractSequential metabolic changes in leg muscles of a model of defective muscle glycolysis that was produced by intraaortic injection of sodium iodoacetate were observed by in vivo31P‐NMR spectroscopy with a surface coil. Spectra obtained from iodoacetate‐treated muscles presenting exercise‐induced cramp showed decreased levels of phosphocreatinine (PCr) and adenosine triphosphate (ATP) and an accumulation of sugar phosphate. The chemical shift of inorganic phosphate (Pi) resonance, which reflects the intracellular pH of the contracted muscles, showed a milder shift to the acidic condition than those of controls. In vivo31P‐NMR study showed dynamic information on the muscle energetics under defective glycolytic con

ISSN:0148-639X    

DOI:10.1002/mus.880090205

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

年代:1986

数据来源: WILEY

摘要:

AbstractTo examine the effects of stretch and starvation on muscle carbohydrate metabolism, glucose uptake was measured using [3H]3‐O‐methylglucose. Glucose uptake was higher in the stretched condition, and more so in soleus muscle than in extensor digitorum longus. After 4 days of starvation, glucose uptake decreased significantly in soleus muscle, but in extensor digitorum longus muscle, glucose uptake per noncollagen protein increa

ISSN:0148-639X    

DOI:10.1002/mus.880090206

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

年代:1986

数据来源: WILEY

摘要:

AbstractProperties of nitrendipine receptors have been analyzed in skeletal muscle from normal young boys and boys with Duchenne muscular dystrophy (DMD). The dissociation constant (Kd) of the complex formed by nitrendipine with its specific receptors was 0.5 ± 0.1 nMin dystrophic muscle and 0.4 ± 0.1 nMin normal muscle. Maximum binding capacitiesBmaxwere 403 ± 80 and 460 ± 60 fmol/mg protein in DMD and normal muscle, respectively. These results suggest that nitrendipine binding sites on nitrendipine‐sensitive Ca2+channel binding sites are not altered in Duchenne muscular dyst

ISSN:0148-639X    

DOI:10.1002/mus.880090207

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe specific activity of dipeptidyl peptidase I in cultured skin fibroblasts from patients with Duchenne muscular dystrophy did not differ significantly from that of controls.

ISSN:0148-639X    

DOI:10.1002/mus.880090208

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

年代:1986

数据来源: WILEY

摘要:

AbstractDuring fetal development of fast skeletal muscles in the rat, three types of cells could be identified using a monoclonal antibody to slow skeletal muscle myosin heavy chain. Presumptive type I cells stained positive for slow forms of skeletal myosin heavy chain and a previously described protein5of an apparent molecular weight of 100 KD, whereas presumptive type 2B cells did not stain for either of these peptides. Presumptive type 2A cells, on the other hand, did not stain for slow isoform of 100‐K protein, but did stain positive for slow skeletal myosin heavy chain. There was a progressive suppression or degradation of slow skeletal myosin heavy chain in presumptive type 2A cells during subsequent fetal development, so that it was almost undetectable in most animals at birth. Soleus, a slow muscle, however, did not show clear differentiation into presumptive type I and type 2 cells until 4 days after birt

ISSN:0148-639X    

DOI:10.1002/mus.880090209

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

年代:1986

数据来源: WILEY

摘要:

AbstractPeripheral neuropathy marked by reduced nerve conduction velocities was found in four unrelated children, betwen the ages of 15 months and 9 years, whose autopsies revealed Leigh's subacute necrotizing encephalomyelopathy. Sural nerve biopsies disclosed primary demyelination and remyelination, as well as loss of myelinated and unmyelinated axons. The use of morphometric and electron microscopic studies shows that these techniques may reveal peripheral neuropathy in Leigh's disease more often than light microscopic methods alone.

ISSN:0148-639X    

DOI:10.1002/mus.880090210

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

年代:1986

数据来源: WILEY

摘要:

AbstractA possible relationship between muscle cell injury or deterioration and enhanced halothane sensitivity was studied by monitoring mechanical responses of skeletal muscles from normal pigs and pigs susceptible to malignant hyperthermia (MH). Increased time postbiopsy and decreased maximum control tetanic tension both correlated significently with enhanced sensitivity to halothane. In both normal and MHsusceptible (MHS) muscles, greater halothane sensitivity was observed in cut cell than in intact cell bundles and in low tetanic tension as compared to high tension preparations. Subsequent to halothane exposure, twitches of high tension (≥ 1.75 kg · cm−2) intact bundles of both normal and MHS muscles were potentiated. Tetani of normal intact bundles were not altered, whereas those of MHS bundles were depressed after halothane exposure. Control twitch‐to‐tetanus ratios (twitch ratios) were higher in MHS (0.23) than in normal (0.12) intact bundles. According to discriminant analysis, the best distinction between normal and MHS muscles, either cut or intact, was obtained by comparing halothane‐induced changes in tetanic tension and control twi

ISSN:0148-639X    

DOI:10.1002/mus.880090211

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

年代:1986

数据来源: WILEY