摘要:

AbstractThe firing ranges of 50 normal anterior tibial or short toe extensor motor units in sustained isometric voluntary contraction were studied in electromyographic recordings. The afferent inflow was decreased by compression of the sciatic nerve, thereby blocking large afferents before alpha efferents. Motor units with low minimum and low maximum rates before blockade had higher minimum and maximum rates on blockade. Some motor units with high minimum and maximum rates before blockade had a lower minimum but an unchanged maximum rate on blockade. The firing range recorded for both types of motor unit on blockade was also recorded for all tonically firing motor units during early reinnervation after traumatic lesion to the muscle nerve in 14 patients. It is concluded that both facilitating and inhibiting proprioceptive afferent activity is involved in the differentiation of motor unit firing ranges in sustained isometric voluntary contraction.

ISSN:0148-639X    

DOI:10.1002/mus.880020602

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe voluntary discharge properties and axonal conduction velocity of single motor units were studied in patients with neuromuscular diseases with retained differentiation of the muscle fibers into type 1 and type 2, and in patients with late‐onset hereditary distal myopathy in which muscle fibers have only intermediate histochemical properties. In the patients with muscle fiber differentiation, the findings were similar to those in normal subjects; that is, there was a continuum between motor units which fired tonically at low rates and had a low axonal conduction velocity, and motor units which fired phasically at high rates and had a high axonal conduction velocity. In the patients without muscle fiber differentiation, all motor units had intermediate firing properties and a low axonal conduction velocity. It is suggested that in chronic pathologic states, the differentiation of the muscle fiber histochemistry remains only as long as the differentiation of the motor neurons remain

ISSN:0148-639X    

DOI:10.1002/mus.880020603

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

年代:1979

数据来源: WILEY

摘要:

AbstractWe report on five patients who presented with unilateral or bilateral hypoplasia of the thenar eminence. X rays of the affected limbs showed varying degrees of malformation and underdevelopment of the thumb phalanges and first metacarpal bone, and of the carpal bones at the base of the thumb, indicating a developmental abnormality. Our electrodiagnostic findings were compatible with this interpretation. We suggest that this condition is part of the clinical spectrum of radial club hand (radial dysplasia) and that when seen in adults, its recognition is important in the differential diagnosis of carpal tunnel syndrome.

ISSN:0148-639X    

DOI:10.1002/mus.880020604

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe histochemical and fine structural profiles of human intrafusal muscle fibers were studied. Spindles were located in freshly frozen specimens taken from biopsied normal external intercostal muscles, and periodic 10‐ and 50‐μm‐thick cross sections were processed alternately for enzyme histochemical and electron microscopic examination. Nuclear bag fibers were of two types, bag1and bag2, histochemically, and they displayed two distinct types of ultrastructure. Nuclear chain fibers were histochemically and ultrastructurally homogeneous. Regional differences in enzymatic staining and ultrastructure occurred along individual intrafusal fibers. Human bag1and bag2fibers appear to be analogous to the two types of nuclear bag fiber identified in animal spindles and are considered to have different roles in spindle function. The presence of three types of intrafusal fibers should be taken into account when studying spindle abnormalities in human neuromuscular dis

ISSN:0148-639X    

DOI:10.1002/mus.880020605

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

年代:1979

数据来源: WILEY

摘要:

AbstractIn five patients with unilateral wasting of the hand muscles as a result of a cervical rib and band, F waves were recorded from the hypothenar muscles following stimulation of the ulnar nerve at the wrist. Twelve healthy control subjects were also examined. F‐wave latency was consistently increased in the affected hands of the patients, compared with results from the unaffected and control hands. This increase persisted after removal of the cervical band in four patients and was thought to be mainly due to degeneration of fast‐conducting fibers. In the fifth patient, F‐wave latency decreased after operation, suggesting recovery of a local conduction block in the proximal part of the

ISSN:0148-639X    

DOI:10.1002/mus.880020606

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

年代:1979

数据来源: WILEY

摘要:

AbstractRecent developments in molecular biology have shown that some genes are split into segments, each coding for part of a protein. The intervening segments are transcribed but later excised, and the messenger RNA is spliced back together again before translation into protein begins. Abnormalities in the nontranslated segments would not be reflected in abnormal protein structure but, presumably, in the control of synthesis of a particular protein. The muscular dystrophies may be an example of this class of disease. They are particularly amenable to investigation of this idea because muscle produces large amounts of relatively few proteins, facilitating isolation of the appropriate messenger RNA.

ISSN:0148-639X    

DOI:10.1002/mus.880020607

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

年代:1979

数据来源: WILEY

摘要:

AbstractElectrical and mechanical responses were evoked in the elbow flexors (EFs) of normal subjects and myopathy patients by maximal stimulation of the musculocutaneous nerve by a wire electrode in the axilla. In normals, the decrement in the mechanical responses during short trains of twitches was small (10%). The potentiation during a staircase decreased with increasing frequency of stimuli, but the potentiation 30 sec after the 100‐sec staircase was the same at all frequencies. Posttetanic potentiation was twice as large as the maximal potentiation attained during the staircase. The staircase phenomenon probably results from two opposing events, diminution and potentiation. Findings in 11 patients with myopathy varied according to the severity of involvement. Slight weakness of the EFs was associated with an increased twitch:tetanus ratio, decreased tetanic tension, and decreases in the staircase and posttetanic potentiation. Additionally, severe weakness of the EFs was associated with a diminution in twitch tensio

ISSN:0148-639X    

DOI:10.1002/mus.880020608

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

年代:1979

数据来源: WILEY

摘要:

AbstractElectrical and mechanical responses of the elbow flexors (EFs) and the adductor pollicis muscle (ADP) were evoked in 31 patients with myasthenia gravis (MG). Thirteen patients with moderate or severe involvement showed a decrement during trains of repetitive stimuli in both muscle types, greater in the proximal ones than in the distal one. Seven of 18 patients with mild generalized or ocular MG showed abnormalities in the EFs, and 4 patients showed abnormalities in the ADP. A regional curare test was performed in the EFs of 11 patients with borderline or no abnormalities in the EFs and the ADP. All patients were more sensitive to curare than were control subjects; in 2, a decrement outside the range of controls could only be provoked in the partly curarized muscle during posttetanic exhaustion. Excitation‐contraction coupling, as evidenced by the staircase phenomenon and after correction for blockade of fibers, was abnormal in 5 of 31 patients in the EFs, and in 11 patients in the ADP. In both muscles, the action potential was a more sensitive criterion of abnormality than the mechanical response. The decrement in the action potentials during 3/sec stimuli gave the largest diagnostic yiel

ISSN:0148-639X    

DOI:10.1002/mus.880020609

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

年代:1979

数据来源: WILEY

摘要:

AbstractHalothane, at clinical concentrations, depolarizes the plasma membrane of skeletal muscle from Poland China pigs susceptible to malignant hyperthermia but does not affect the resting membrane potential of muscle from normal Poland China pigs, mice, or frogs. The depolarization is reduced or partially reversed in the presence of dantrolene sodium. We suggest the possibility that malignant hyperthermia may be initiated by this abnormal depolarization of skeletal muscle by halothane.

ISSN:0148-639X    

DOI:10.1002/mus.880020610

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

年代:1979

数据来源: WILEY

摘要:

AbstractOne of the features of the IVth International Congress on Neuromuscular Diseases, held in Montreal September 17–21, 1978, was a series of invited posters. In order to achieve a wider audience for this valuable material, we have made arrangements to publish a number of these posters inMuscle&Nerve. This is the third poster in this series. To preserve the original effect of the posters, they are being reproduced almost exactly as they appeared at the Congress, without editing or other alterations. We hope you will find this feature a useful addition to your Journa

ISSN:0148-639X    

DOI:10.1002/mus.880020611

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

年代:1979

数据来源: WILEY