摘要:

AbstractThe properties of singles K+channels in normal and denervated muscles were compared using the “patch‐clamp” technique. Single channels were recorded from vesicles obtained by stretching bundles of normal and denervatedextensor digitorium longus(EDL) muscles. The most frequently observed channel in normal muscles was a high conductance (266 pS) Ca++activated K+channel. Although channel density, as estimated by patch recording, showed a significant decrease in denervated muscles, no differences were found in conductance and gating properties. Another voltage‐dependent K+channel (81 pS) was only recorded from normal muscles, but never from denervated ones. In addition, a 35 pS conductance was recorded from both normal and denervated fibers. This channel displayed neither voltage dependence nor sensitivity to tetraethylammonium (TEA). In contrast, another TEA‐insensitive (16 pS) channel was recorded only from denervated muscles. We conclude that denervation induces significant changes in the distribution and expression of K+channels in mammalian skeletal muscles. © 1993 John Wiley

ISSN:0148-639X    

DOI:10.1002/mus.880160602

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe studied the role of antiganglioside antibodies in the pathogenesis of autoimmune neuropathies using an in vitro preparation of a rat sciatic nerve. Human and rabbit sera with high titers of the antibodies were applied to a restricted segment of the sciatic nerve mounted in a recording chamber, and the compound nerve action potentials of the myelinated and unmyelinated fibers were observed. Myelinated fiber conduction became blocked at the segment within a few hours, whereas the unmyelinated fiber conduction remained unchanged. These results suggest that antiganglioside sera directly produce an acute conduction block only in myelinated nerve fibers and that this in vitro model is useful for studying the ionic mechanism by which the acute conduction block occurs. © 1993 John Wiley&Sons, Inc

ISSN:0148-639X    

DOI:10.1002/mus.880160603

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

年代:1993

数据来源: WILEY

摘要:

AbstractA high level of glucose‐6‐phosphate dehydrogenase (G6PD) activity was observed in myoblasts and myotubes from normal human and mouse cell cultures. However, only a residual amount of activity was observed in myoblasts and myotubes obtained from G6PD‐deficient patients (G6PD Mediterranean). Hybrids were formed by the fusion of normal (from human and mouse) and G6PD‐deficient myoblasts (from the patients). These hybrids contained a high level of G6PD activity. Hoechst staining permitted to confirm that the enzymatic activity was not restrained to a domain near the competent nuclei. These results suggest that myoblast transplantation could be used to restore normal enzymatic activity in metabolic myo

ISSN:0148-639X    

DOI:10.1002/mus.880160604

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

年代:1993

数据来源: WILEY

摘要:

AbstractChanges in EMG power spectrum during isometric voluntary contraction maintained until exhaustion in the range of 20–80% MVC were studied in three skeletal muscles (adductor pollicis or AP, vastus lateralis, and medialis) and two respiratory muscles (diaphragm and rectus abdominis). Quantitative EMG analysis consisted of computation of the median frequency (MF) of power spectra and also the continuous measurement of EMG power in two bands of high (EH) and low (EL) frequencies using bandpass filters. This allowed the calculation of the H/L ratio and its time constant of decay rate (TCHδ /L) throughout the sustained static contraction. The main results were: (1) highly significant, positive correlations between TCδH/L and the maximal MF changes and also the endurance time to fatigue; (2) EMG changes were determined early, within the first 10–20 s of contraction; and (3) EL always increased throughout the fatiguing isometric contraction, but EH changes markedly varied within the five muscle groups studied. These observations are discussed in terms of the differences in muscle fiber composition and also the variations in motor unit recruitment. © 1993 John Wiley&Son

ISSN:0148-639X    

DOI:10.1002/mus.880160605

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

年代:1993

数据来源: WILEY

摘要:

AbstractIncreased titers of anti‐GM1 antibodies have been associated with motor neuron disease and motor neuropathy with or without conduction block. To investigate the pathogenetic role of anti‐GM1 antibodies we injected into rat tibial nerves sera from patients with multifocal motor neuropathy and conduction block (MMN) or progressive spinal muscular atrophy (PMA), both presenting anti‐GM1 antibodies. Sera of patients with MMN produced reduction of amplitude and dispersion of compound muscle action potential from proximal stimulation. Morphometry revealed demyelination in 6.2% of fibers. Sera of patients with PMA did not produce clear‐cut electrophysiological or morphological changes. Differential effects of sera from patients presenting high‐titer anti‐GM1 antibodies, but with distinct clinical syndromes, might depend on differences in anti‐GM1 antibody affinity, valency, or ability to fix complement. Alternatively, circulating factors other than, or in addition to, anti‐GM1 antibodies present in sera of patients with MMN, but not of PMA patients, might be responsible for conduction abnormalities and reproduce them after passive transfer. © 1993 John

ISSN:0148-639X    

DOI:10.1002/mus.880160606

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe physical properties of recording electrodes coupled with the input characteristics of recording amplifiers can affect motor unit parameters. In recent years, there has been increased use of disposable needle electrodes; thus, a comparison of impedance characteristics with disposable types is of interest. Impedances at 10, 100, 1000, and 10,000 Hz of eight different electrode models including concentric and monopolar, both disposable and reusable, were measured. For all models of monopolar electrodes, no significant difference in impedance was found between disposable and nondisposable types. Intramodel variability was seen, however, with a twofold difference between minimum and maximum impedances for each model. For concentric electrodes, a moderate difference in impedance was found between disposable and nondisposable types, but less intramodel variability was seen; there was also more intermodel variability. To determine whether the measured impedances could affect recorded motor unit potentials, a theoretical analysis was conducted using typical waveforms along with circuit analysis techniques. Electrode impedances as high as 50 times nominal values caused no significant waveform distortion. © 1993 John Wiley&Sons, Inc

ISSN:0148-639X    

DOI:10.1002/mus.880160607

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

年代:1993

数据来源: WILEY

摘要:

AbstractBased on the known trophic effects of growth hormone (GH) on nerve and muscle 75 patients with ALS were treated for up to 18 months with synthetic human growth hormone (Protropin) or a placebo. The course of ALS was assessed serially using a quantitative (TQNE) neuromuscular and manual exam (MRC) and laboratory chemistries. Average insulin‐related growth factor (IGF‐1) values increased from 1.2 to 2.3 U/mL in the treated group. Surprisingly, serum insulin levels did not increase. Hyperglycemia was noted in only 2 patients of the 38 patients receiving hGH, and this resolved with cessation of treatment. Over the 12 months of treatment there were 11 deaths (6 controls, 5 treated). Survival analysis, performed approximately 12 months following cessation of treatment, did not reveal a difference between the treatment and placebo group. The TQNE scores declined inexorably in both the control and treated group. Retrospective analysis of the TQNE data indicate a poor prognosis for patients who lost arm strength early. A correlation between the TQNE and MRC scores was evident at early stages of motor unit loss, less so when muscle weakness was advanced. © 1993 John Wiley&Sons,

ISSN:0148-639X    

DOI:10.1002/mus.880160608

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe evaluation of peripheral nerve regeneration is of great interest in clinical as well as in experimental situations. However, there are few techniques that give early and quantitative information on the states of the regeneration process. If quantitative assays would be available, different surgical techniques and medications could be evaluated more accurately in relation to axonal ingrowth and functional recovery. The purpose of this study was to investigate the merits of nerve compound action signals (NCASs) recorded electrically and signals recorded with a novel magnetic recording technique. We compared the two techniques in the rabbit peroneal nerve, 2, 4, 6, and 8 weeks after a nerve reconstruction. Our conclusions are that the signals recorded with the magnetic sensor are far more reproducible and less prone to stimulus artifact than the electrically recorded signals. Furthermore, the magnetic recording shows that the number of axons that have regenerated increases with time. Previously, this could only be determined with histological studies. Other ingrowth parameters that can be quantified are the average ingrowth distance, and the variation between axons in ingrowth velocity. © 1993 John Wiley&Sons, Inc

ISSN:0148-639X    

DOI:10.1002/mus.880160609

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe earlier reported cases of 2 patients with severe acute Guillain–Barré syndrome (GBS) associated with high‐IgG anti‐GD1aantibody titer. We now have investigated the autoantibody against GD1aor GM1in 37 GBS patients using the enzyme‐linked immunosorbent assay and have found a statistically significant association between IgG anti‐GD1aantibody and the severity of the disease (need of a respiratory for more than 1 month and a poor functional prognosis 3 months after neurologic onset). An autopsy which showed severe GBS associated with IgG anti‐GD1aantibody produced the following findings: (1) severe axonal degeneration and segmental demyelination of peripheral nerves; (2) lymphocytic infiltration; and (3) marked central chromatolysis of the lower motoneurons. © 1993 John Wi

ISSN:0148-639X    

DOI:10.1002/mus.880160610

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

年代:1993

数据来源: WILEY

摘要:

AbstractPaired stimulation has been used extensively in clinical neuropathysiology. We studies change in the sizes of compound muscle action potencial (CNAPs) in humans after a single electrical stimulus to the peripheral nerve. When the interstimulus intervals were varied, the second potentials underwent refractoriness and then were facilitated up to 20–30 ms, thereafter being depressed for 160–200 ms. When intensities were graded at fixed intervals for motor fibers the maximal effects was obtained with liminal stimulation, but was no longer observed at supramaximal stimulation. When the intrensity used to obtain M‐resposes was half the maximum, maximal facilitations were 35% (CNAP) and 17% (CMAP) of the first potential, the respective maximal depressions being 13% and 42%. When the sizes of the two CNARs were equalized by adjusting the second stimuli, the CMAP was facilitated (26%) up to 65 ms, thereafter being depressed (13%). These results must be taken into account when making clinical examinations that use paired stimulation. © 1993 John Wiley&Son

ISSN:0148-639X    

DOI:10.1002/mus.880160611

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

年代:1993

数据来源: WILEY