摘要:

AbstractClinical testing for neuromuscular dysfunction is supported by an extensive amount of excellent basic information about normal and abnormal subcellular physiology and ultrastructure. This information provides an essential frame of reference for describing the rationale of single‐fiber electromyography (SFEMG). SFEMG in turn helps to explain the more conventional clinical testing of neuromuscular function by repetitive nerve stimulation (RNS). Electrical findings in myasthenia gravis, Lambert–Eaton myasthenic syndrome, and botulinum intoxication are discussed from the subcellular level via the cellular level (SFEMG) to the integrated responses of whole muscle (RNS) as a rational means of understanding the technique of clinical repetitive nerve stimulat

ISSN:0148-639X    

DOI:10.1002/mus.880120802

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe blood–nerve barrier (BNB) for serum proteins was studied after a crush lesion of the murine sciatic nerve or after transsection with persistent Wallerian degeneration. Using single intraperitoneal injections of biotinylated human albumin, transferrin, IgG, and complement components as tracers, the integrity of the BNB during degeneration and regeneration was determined over time. In Wallerian degeneration induced bycrushthe BNB became increasingly leaky, with a maximum in the distal stump 8 days after crush (i.e., during early regeneration). When regeneration potentials could first be elicited from the small foot muscles and when thinly myelinated nerve fibers were present, the BNB gradually regained its barrier function and was nearly intact on day 30 after crush. Aftertranssectionbreakdown of the BNB persisted beyond 30 days. The BNB leakage may foster repair by allowing exchange of trophic factors of large molecular size during nerve regeneratio

ISSN:0148-639X    

DOI:10.1002/mus.880120803

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

年代:1989

数据来源: WILEY

摘要:

AbstractMagnetic and electric activation of limb nerve and muscle were compared in normal subjects of different age, gender, and habitus. Direct stimulation of nerve and muscle showed that activation of intramuscular nerve fibers in the arm and leg occurs at a lower threshold for magnetic stimulation than for electric stimulation. Sensory nerve fibers had a lower threshold with electric stimulation. Muscle activation and stimulus artifact with magnetic stimulation precluded reliable recording of distal sensory nerve action potential in all subjects.

ISSN:0148-639X    

DOI:10.1002/mus.880120804

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

年代:1989

数据来源: WILEY

摘要:

AbstractClonal, fusing, mouse skeletal muscle cells (C2) were grown to the myotube stage (90% confluence) before they were subjected to isotope containing serum‐free media (3H‐proline or35S‐methionine). C2 myotubes secrete and organize a biosynthetically labeled matrix which adheres to the plastic after removal of myotubes with detergent and ammonium hydroxide. When these homotypic‐labeled myotube matrices were incubated with myo blast‐conditioned media containing high specific activity urokinase‐type plasminogen activator, slow, but clearly detectable, release of label occurred. However, degradation of matrix, with solubilization of label, was accelerated sixfold by addition of human plasminogen to diluted myoblast conditioned media. If protease nexin I, a cellular serine protease inhibitor purified from human fibroblast‐conditioned media, was added (0.2 μg/ml) with plasminogen, inhibition of matrix hydrolysis by 52% occurred. Higher concentrations (0.8 μg/ml or above) of protease nexin I completely inhibited the degradation of extracellular matrix components. A similar protease inhibitor was purified from C2 myotube‐conditioned media, and this molecule also inhibited the plasminogen‐dependent release of extracellular matrix. We propose that protease nexin I inhibits the destruction of myotube matrix by inactivating the plasmin/plasminogen activation system and may be the physiologic regulator of this system during muscle

ISSN:0148-639X    

DOI:10.1002/mus.880120805

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

年代:1989

数据来源: WILEY

摘要:

AbstractRecruitment and firing rate modulation (FRM) of single motor units (MUs) were evaluated in the first dorsal interosseus muscle in patients with chronic lower motor neuron disorders of primarily neuroaxonal or demyelinating pathology. Residual muscle function was estimated by maximal voluntary force, twitch tension, and compound muscle action potential. The recruitment range of MUs was expanded toward higher relative force levels in all patients. Changes in firing rates per unit force increment were larger in patients with more pronounced muscle atrophy. When this effect was accounted for by calculating FRM for increments of 10% of residual maximal force, patients with subnormal motor nerve conduction velocities showed selective impairment of rate modulation. This was not due to intermittent conduction failure. We conclude that the two force‐generating mechanisms, recruitment and FRM, show unspecific compensatory changes related to the loss of MUs and also alterations that are specifically related to the neuroaxonal or demyelinating nature of the neuropath

ISSN:0148-639X    

DOI:10.1002/mus.880120806

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe study of muscle fatigue started about a century ago, when it was proposed that the observed decrease in force during prolonged voluntary contractions resulted from changes in central processes which reduced the motor drive. In the middle of this century it was noticed that this loss of force could not be restored by maximal electrical stimulation of the motor nerve, and thus the importance of peripheral mechanisms, located beyond the motoneuron, was emphasized. However, it was not clear which peripheral site was most important in decreasing the muscle mechanical capacity during fatigue. More recently, the comparison between peripheral failures during sustained and intermittent contractions indicated that recorded mechanical changes underwent deterioration which was not closely related to the recorded electrical changes. It was thus proposed that muscle intracellular processes dominate the force decrease during muscle fatigue. This concept has been substantiated by the study of standard fatigue tests performed in control, trained, and disused human muscles, as reviewed in this paper.

ISSN:0148-639X    

DOI:10.1002/mus.880120807

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe compared acid α‐glucosidase of acid maltase‐deficient Japanese quails, an animal model of human late‐onset glycogenosis type II, with that of normal controls. Antibody produced in a rabbit against acid α‐glucosidase purified from chicken pectoral muscle cross‐reacted with that of Japanese quails. The presence of a 110K and 98K form of acid α‐glucosidase was confirmed in normal controls by immunoblotting. However the 98K form was absent in the affected quails. Subcellular distribution studies demonstrated that the 98K form, but not the 110K form, was localized in the lysosomes. This suggests that the 110K form is a precursor of the mature 98K form of acid α‐glucosidase. In the affected quails, the 11OK precursor is synthesized, but maturation to the 98K form does not occur or may be ex

ISSN:0148-639X    

DOI:10.1002/mus.880120808

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

年代:1989

数据来源: WILEY

摘要:

AbstractThree well‐characterized antimyosin heavy chain monoclonal antibodies (McAbs) were used as immunocytochemical reagents to study myosin iso‐form expression in relationship to adenosine triphosphatase (ATPase) defined fiber types in human muscle. The biopsy specimens were from patients with neurogenic muscle disease whose muscle exhibited fiber type grouping and group atrophy. The use of McAbs revealed heretofore unrecognized coexpression of multiple myosin isoforms in selected fibers in the pathologic samples which was not apparent with ATPase reactions and not present in normal muscle. The fibers containing multiple myosin isoforms were probably undergoing neurally directed fiber type transformation. Furthermore, a small population of fibers in neurogenic specimens expressed a “prenatal” myosin signifying the presence of regenerating fibers. We also demonstrated immunocytochemical evidence of the persistence of adult slow myosin in denervated mature human skeletal muscle despite the reputed necessity of innervation for maintenance of expression of this myosin isoform proffered by

ISSN:0148-639X    

DOI:10.1002/mus.880120809

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn two patients with hemifacial spasm (HFS), single‐fiber EMG recordings in facial muscles demonstrated low jitter in the late responses produced by stimulation of peripheral branches to other facial muscles. Surgical decompression of the facial nerve in one patient was followed by clinical improvement and disappearance of the abnormal late responses. These observations are consistent with the hypothesis that there is ephaptic transmission among peripheral branches of the facial nerve at the site of compression in HF

ISSN:0148-639X    

DOI:10.1002/mus.880120810

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

年代:1989

数据来源: WILEY

ISSN:0148-639X    

DOI:10.1002/mus.880120811

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

年代:1989

数据来源: WILEY