摘要:

AbstractThe change in muscle fiber size and fiber percentage was studied in three heads of the dog quadriceps following 10 weeks of immobilizationg using an external skeletal fixator. Muscle biopsy morphometric analysis revealed that muscle fiber atrophy was greatest for the vastus medialis and least for the rectus femoris. The atrophic response for type 1 fibers was, in order from most to least atrophied: VM>VL>RF, whereas for type 2 fibers the corresponding order was VM = VL>RF. An increase in connective tissue was also observed for all muscles. These results are discussed in terms of skeletal muscle architecture, initial fiber‐type distribution, and level of use. As a result, predictions are made as to the muscles that are most vulnerable to disuse atrophy, namely the postural muscles that contain a relatively large proportion of slow muscle fibers and cross a single joint. Conversely, those that are least susceptable to atrophy are those that are not used as postural muscles, that cross multiple joints, and that are predominantly composed of fast muscle fiber

ISSN:0148-639X    

DOI:10.1002/mus.880110302

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe isometric force of arm and leg muscles was studied in five unrelated patients with recessive generalized myotonia (Becker). The symptom of myotonia was present mainly in the legs, whereas transient weakness was the prominent symptom in the arms. Tocainide improved both symptoms, although it improved the stiffness more than the weakness. A specimen of intact muscle fibers was excised from the external intercostal muscle of one of the patients. The resting potential of the fibers was normal, but on injection of depolarizing current the fibers responded with repetitive action potentials. In normal interstitial fluid the current‐voltage relationship was N‐shaped, with a region of negative slope between −70and −55 mV. Replacement of chloride by an impermeant anion changed this relationship very little, suggesting an abnormally small chloride conductance. The potassium current through the inward‐going rectifier was larger than normal. The force of tetanic contractions of a rested bundle was not sustained but fell quickly to a plateau that increased with repeated stimulation. The relaxation of a rested tetanus was slow and accompanied by spontaneous electrical activity. In subsequent contractions the relaxation became faster and electrical after‐activity decreased. However at 23°C the speed of relaxation was always high despite a large amount of electrical after‐activity. The electrical instability of the membrane and the transient weakness can be explained on the basis of the N‐shaped membran

ISSN:0148-639X    

DOI:10.1002/mus.880110303

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

年代:1988

数据来源: WILEY

摘要:

AbstractStrenuous exercise can result in muscle injury that may persist for 2 weeks. Our purpose was to determine if muscle injury can be detected with 31‐P magnetic resonance spectroscopy. Normal subjects performed repeated lengthening contractions with either arms or legs designed to result in mild muscle injury. One hour after the arm exercise, there was a significant increase in the inorganic phosphate to phosphocreatine ratio (Pi/PCr), with the maximum increase in Pi/PCr occurring 1 day postexercise (0.12 ± 0.01 to 0.21 ± 0.05). Pi/PCr remained elevated for 3–10 days. Similar results were seen following the leg exercise protocol. ATP/(Pi+PCr) decreased in all the arm exercised subjects. Exercise protocols that did not contain lengthening contractions did not result in changes of Pi/PCr or ATP/(Pi+PCr). Patients with various neuromuscular diseases with evidence of muscle damage (elevated CK, muscle soreness, and histopathological findings) also showed increased Pi/PCr at rest. We conclude that elevated Pi/PCr at rest can reflect nonspecific muscle damage in normal and diseased sub

ISSN:0148-639X    

DOI:10.1002/mus.880110304

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe ratios of F to M amplitudes were determined by dividing the mean amplitude of 15 F‐waves (mF AMP) by the maximum evoked motor response amplitude recording from the abductor pollicis brevis and calf muscles. Data were compared from age‐matched control subjects and patients with polyneuropathies or spastic hyperreflexia. In comparison to normals, mF AMP/M—but not mF AMP—values were increased at statistically significant levels in all patient groups. M amplitudes were decreased (versus normal,P<0.005) in the patients with either peripheral or central lesions. In these patients, the normal significant correlation between mF AMP and M amplitudes may be disrupted, whereas the data suggest that increased mF AMP ratios in neuropathies are related to their duration. These results indicate that mF AMP/M ratios can be increased not only with increased central excitability but also in peripheral neuropathies. Although mechanisms may differ, the data are consistent with a similar physiological response to peripheral and central injury and emphasize that M amplitudes may be decreased with central

ISSN:0148-639X    

DOI:10.1002/mus.880110305

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

年代:1988

数据来源: WILEY

摘要:

AbstractMorphometric analysis of 90 intramuscular nerves from the biopsied biceps muscles of 16 cases of amyotrophic lateral sclerosis (ALS) were done and compared with controls. In all fascicles (large and small) of ALS, the total number and the numbers of large and small myelinated fibers were significantly reduced to 52, 16, and 64% of controls, respectively. A histogram of the largest fascicles revealed a unimodal distribution and a shift to the left, showing a single peak at 1 μm diameter. The results indicate proximal and distal involvement of the most remote portions of the nerves to the muscle in ALS and support previous suggestions of a neuronopathy

ISSN:0148-639X    

DOI:10.1002/mus.880110306

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

年代:1988

数据来源: WILEY

摘要:

AbstractAbnormalities of GM2ganglioside metabolism owing to hexosaminidase A (Hex A) deficiency have been associated with ALS phenotypes. The clinical features described in these ALS patients with Hex A deficiency include early onset, positive family history, and/or long disease duration. In an attempt to determine prospectively the incidence of Hex A deficiency within an ALS population, the records of The Mount Sinai Medical Center ALS Clinic were reviewed to select those patients with “atypical” ALS (total N = 52), i.e. onset before age 35, positive family history, and/or disease duration greater than 90 months. The control group (total N = 50), “typical” ALS patients, did not fulfill any of these historical criteria. Hex A activity determined in isolated peripheral blood leukocytes was normal in all typical ALS patients (mean 67.3%). Hex A deficiency was not found in any atypical ALS patients. Thus, Hex A deficiency apparently is an unusual etiology of typical or atypical ALS but is of medical and genetic importance in individual f

ISSN:0148-639X    

DOI:10.1002/mus.880110307

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

年代:1988

数据来源: WILEY

摘要:

AbstractThis study determined the morphological changes and adaptations that occur following immobilization of rat soleus and gastrocnemius muscles when the ankle joint is placed in complete plantar flexion for 2, 5, 7, 14, 21, and 28 days by means of plaster casts. Previous studies of such shortened muscles have shown that the number of sarcomeres in series is reduced, but how the sarcomeres are reduced has not been determined. We observed that the fibers in the midbelly region of the muscles demonstrated a progressive degenerative process over the first few weeks. Myofibrils across the entire width of the affected fibers underwent dissolution. However, by 4 weeks new myofibrils were being formed, and sarcomere lengths appeared normal. Portions of the fibers near the tendon underwent segmental necrosis. These findings are similar to the response of the soleus and gastrocnemius muscles to tenotomy and are clinically relevant to orthopedic procedures that maintain muscles in shortened conditions for prolonged periods.

ISSN:0148-639X    

DOI:10.1002/mus.880110308

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

年代:1988

数据来源: WILEY

摘要:

AbstractMotor units from the cat tibialis posterior muscle were examined for an association between physiological and biochemical properties. Functionally isolated motor units were categorized on the basis of their physiological properties. This was followed by quantitative microbiochemical analysis of single muscle fibers from each unit, identified in cross sections using the glycogen‐depletion method. The activities of malate dehydrogenase and β;‐hydroxyacyl‐CoA dehydrogenase distinguished between fatigable (type FF) and fatigue‐resistant (types FR and S) units. The activities of both lactate dehydrogenase and adenylokinase were higher in fast‐than in slow‐contracting units. Cluster analyses, based on both physiological and biochemical properties alone, produced groupings identical to types FF, FR, and S. The association between physiological and biochemical properties substantiates the idea that biochemically distinct groups of motor units correspond to physiologically identif

ISSN:0148-639X    

DOI:10.1002/mus.880110309

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

年代:1988

数据来源: WILEY

摘要:

AbstractWe report a patient with clinical vermiform motor activity, muscle cramps, delayed relaxation of grip, and continuous motor unit discharges who developed mild symmetric symptoms in the upper extremities following a viral infection. Treatment with carbamazepine produced considerable symptomatic improvement. Needle electromyography (EMG) in several muscles showed irregular grouped spontaneous discharges composed of potentials resembling normal motor units. The discharges occurred asynchronously in distal muscles with identical and different peripheral nerve innervation but were not seen in more proximal muscles innervated by the same nerves. Our EMG findings indicate an origin of this spontaneous activity in the terminal branched motor nerves.

ISSN:0148-639X    

DOI:10.1002/mus.880110310

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

年代:1988

数据来源: WILEY

摘要:

AbstractThere were 72 diabetic patients with clinical evidence of sensorimotor peripheral neuropathy investigated to determine the sensitivity of the sympathetic skin response test (SSR) for detection of sudomotor dysfunction and its correlation with other autonomic function tests, autonomic symptoms, and degree of peripheral neuropathy. Nerve conduction velocities (NCV) were abnormal in all patients, SSR was absent in 60 of 72 patients (83%), Valsalva test was abnormal in 32 of 67 patients (48%) who had the test, and 6 of 72 (9%) had orthostatic hypotension. Statistically significant correlation was found between the Valsalva test abnormality, the degree of peripheral neuropathy, and the SSR in our patients. All patients with orthostatic hypotension had an absent SSR and an abnormal Valsalva test. Most patients had one or more autonomic signs or symptoms. Orthostatic dizziness only correlated with SSR, however. These results suggest that subdomotor activity detected by sympathetic skin response is a valuable test for investigation of dysautonomia in diabetic peripheral neuropathy.

ISSN:0148-639X    

DOI:10.1002/mus.880110311

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

年代:1988

数据来源: WILEY