摘要:

AbstractSkeletal muscle extracellular carbonic anhydrase III was investigated in anesthetized rats by a microdialysis technique. A small dialysis probe was inserted into the tibialis anterior (TA) muscle and perfused continuously. Perfusates were collected before and during muscle contraction, induced by electrical stimulation of the muscle or of the sciatic nerve. In the perfusate of resting normal and denervated muscle, the concentration of CA III was 10 to 12 ng/mL, as measured by a radiommunosorbent technique. During contractile acitvity, the concentrations of CA III increased markedly in hte normal and denervated muscle. A TA muscle suspended in physiological saline behaved similarly, even though the leakage before and during contrafction was higher than in vivo. The results show that skeletal muscle leaks CA III both in vivo and in vitro, a leakage which was markedly increased by contractile activity. The microdialysis technique should also be useful in humans to study the efflux of various proteins from different kinds of diseased or fatigued muscles.

ISSN:0148-639X    

DOI:10.1002/mus.880150602

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

年代:1992

数据来源: WILEY

摘要:

AbstractWe studied neuromuscular transmission in 16 patients with prior poliomyelitis by measuring single fiber electromyographic (SFEMG) jitter. This was compared with 3 indirect methods of assessing reinnervation: SFEMG fiber density, macro EMG, and the presence of fibre type grouping on muscle biopsy. In patients with acute poliomyelitis before the age of 10, there was a positive correlation between the extent of neuromuscular transmission impairment, demonstrated by increased SFEMG jitter, and the enlargement of the motor unit, as indicated by increased fiber density, increased macro EMG signals, and fiber type grouping on muscle biopsy. However, there was no correlation between any of these parameters and the presence or absence of new symptoms of weakness. These findings suggest that impaired neuromuscular transmission is most common in patients with prior poliomyelitis whose motor units have been maximally enlarged by axonal sprouting, but is independent of the presence or absence of new symptoms of weakness.

ISSN:0148-639X    

DOI:10.1002/mus.880150603

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe latency fluctuation of single motor unit potentials (MUPH) in the H‐reflex is greater than the latency fluctuation of MUPs in the direct (MUPM) and recurrent (MUPF) responses. This has been attributed to the variability in the impulse generation at the site of nerve stimulation, and to the variation in the synaptic delay at the anterior horn cell. We studied the latency fluctuation of single motor unit H‐reflex in patients with motor neuron disorders (MND) in comparison with normal subjects. The mean jitter of the H‐reflex was 264.3 ± 17.8 μs (mean ± SEM) in 30 MUPHrecorded from 10 patients with ALS, 302.7 ± 25.2 μs in 16 MUPHfrom 6 patients with chronic motor neuron diseases, as compared with 137.4 ± 7.3 µs in 34 MUPHrecorded from 10 normal subjects. This difference, which persisted even after the correction for the latency variation of MUPM, cannot be explained on the basis of an enhanced reciprocal inhibition. Thus, the increased latency fluctuation of the single motor unit H‐reflex in patients with MND may reflect changes in the motoneuron pool excitability that may be secondary to altered intrinsic electrophysiological properties of motoneurons, or to an abnormal temporal and spatial summation of synaptic inputs

ISSN:0148-639X    

DOI:10.1002/mus.880150604

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to evaluate sweating and cardiovascular autonomic function in patients with distal small fiber neuropathy (DSFN). Sweat testing by the quantitative sudomotor axon reflex test was abnormal in 32 of 40 (80%) patients. The thermoregulatory sweat test was abnormal in 18 of 25 (72%) patients; one or both tests were abnormal in 36 of 40 (90%). Minor heart rate abnormalities were present in 11 of 40 (28%) patients. We conclude that, in patients with DSFN: (a) the sympathetic sudomotor fibers are frequently affected, and that evaluation of sweating is a useful diagnostic test; (b) that the autonomic nerves controlling heart rate are less affected.

ISSN:0148-639X    

DOI:10.1002/mus.880150605

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

年代:1992

数据来源: WILEY

摘要:

AbstractFailure to take body height into considerations in the evaluation of nerve conduction velocities (CV) has recently been deemed unacceptable. This statement prompted the present study. Besides height, the influence of age, gender, and temperature was studied in 92 normal subjects, half of whom were females. The CV decreased 0.9 m/s per 10 years increase in age, the same in women and men aged 15 to 44 years. Mean temperature between distal and proximal ends of the nerve segment examined increased 6.1 ± 0.3° C after heating followed by a CV increase of 7.0 ± 0.5 m/s. The CV decreased 0.15 m/s per 100‐mm increase in heights. When considering 37 individuals aged 25 to 34 years only, the CV increased 0.34 m/s per 1‐m increase in height. In both instances, the changes were within the experimental error (2.3%) of the

ISSN:0148-639X    

DOI:10.1002/mus.880150606

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe objective of this study was to determine whether increased contractile activity is beneficial or detrimental to developing dystrophic muscle. Hamsters (20‐days‐old) were gradually introdued to running at a speed of 14m/min at 10% grade for 2 (T2) or 4 (T4) h/d for 4 weeks, 5 d/wk. Histological and fiber type properties were determined in the soleus (SOL), plantaris (PL), and extensor digitorum longus and contractile properties in SOL and PL from 5 animals/group, including 5 controls. Experimental animals had normal body and muscle mass. Training for 2 h/d had little effect on SOL contractile properties, whereas 4 h/d resulted in significant increases in force, percentage of type I fibers, and type I hypertrophy. Force also increased in PL. Muscle necrosis was reduced in SOL (T2 and T4) and unchanged in PL. In conclusion, endurance training generally had a beneficial or, at least, no detrimental effect on developing dystrophic musc

ISSN:0148-639X    

DOI:10.1002/mus.880150607

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

年代:1992

数据来源: WILEY

摘要:

AbstractA method is described for performing needle electromyography of the diaphram which is safe and causes little discomfort. It provides valuable information concerning neuropathies and myopathies which may affect the diaphragm, and complements information derived form phrenic nerve conduction studies. Firing patterns of motor unit potentials during spontaneous respiration identify upper motor neurone disorders causing respiratory insufficiency.

ISSN:0148-639X    

DOI:10.1002/mus.880150608

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

年代:1992

数据来源: WILEY

摘要:

AbstractWe prospectively evaluated 21 patients with prolonged ventilator dependency, to determine the frequency of unsuspected neuromuscular disease as a cause of this condition, and to determine the types of such diseases. Assessment was performed with routine and specialized electrophyiologic procedures. None of the patients had known prior neuromuscular disease, and none of had ongoing medical problems that could account for their continued ventilator dependency. Sixty‐two precent were found to have a neuromuscular disease severe enough to account for the ventilator dependency. Most of the remaining cases had a contributory neuromuscular disease. In addition to critical illness polyneuropathy, several other significant categories were identified. Myopathic EMG changes were found in 50% of the subgroup assessed by quantitative EMG. We conclude that neuromuscular disease is the most important factor in prolonged ventilator dependency, and that disease other than critical illness polyneuropathy represent an important cause of this syndrom

ISSN:0148-639X    

DOI:10.1002/mus.880150609

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

年代:1992

数据来源: WILEY

摘要:

AbstractAfter nerve transection, the distal stump undergoes Wallerian degeneration (WD). Little information is available concerning sequential changes in nerve conduction measurements during WD in humans. Five patients with nerve injuries were studied temporally. Motor‐evoked amplitudes were reduced by 50% at 3 to 5 days after injury; the response was absent by day 9. Sensory‐evoked amplitudes were reduced by 50% at 7 days after injury; the response was absent by day 11. Sensory and motor nerves with shorter distal stumps showed earlier loss of amplitude than did those with longer distal stumps. Denervation potentials were seen 10 to 14 days after injury. Our results suggest that WD occurs earlier if the distal stump is shorter, and that motor‐evoked responses are affected earlier than sensory‐evoked responses. The time‐lag between the loss of the motor‐evoked response and the appearance of denervation potentials, the latter coinciding with reduction of sensory evoked responses, suggests that failure of neuromuscular transmission precedes axonal los

ISSN:0148-639X    

DOI:10.1002/mus.880150610

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

年代:1992

数据来源: WILEY

摘要:

AbstractChanges in myosin heavy chain (MHC) mRNAs were studied in rabbit fasttwitch muscles during continuous electrical stimulation at 10 Hz for periods up to 3 weeks, and during the first 12 days of the recovery process that followed cessation of 6 weeks' stimulation. Two cDNA probes were used to detect MHC mRNAs specific to fast‐ and slow‐twitch skeletal muscle in RNase protection assays and Northern‐ and slot‐blot analyses. The isolation and base sequence of one of these probes, corresponding to the MHC gene expressed in soleus (slow‐twitch), is described. At an early stage of the response to stimulation, fast MHC mRNA was replaced by slow MHC mRNA. During recovery, this process occurred in reverse but took longer. The time course of recovery was slightly faster in tibialis anterior than in extensor digitorum longus. The changes in mRNAs during both stimulation and recovery reflected changes in the corresponding muscle

ISSN:0148-639X    

DOI:10.1002/mus.880150611

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

年代:1992

数据来源: WILEY