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71.
Eva Magyar A. Talerman W. C. de Bruijn Judith Mohácsy H. W. Wouters 《Virchows Archiv : an international journal of pathology》1979,382(2):191-200
Summary Ultrastructural features of muscle spindles were studied in biopsy material from 100 patients suffering from classical rheumatoid arthritis. Thickening of the outer capsule, increased amount of extracellular ground substance within the inner capsule, and marked thickening of the basement membrane of capillary blood vessels supplying the muscle spindles were observed. Chronic inflammatory cells and macrophages were present within the spindles. Changes affecting the intrafusal muscle fibres were also seen. They were manifest as atrophy and degeneration of the intrafusal muscle fibres, absence of the specialised junctional complexes, and of the intercellular bridges, microladders and satellite cells. It is suggested that the changes affecting the intrafusal muscle fibres are probably secondary. Damage to the myelinated nerves was present, while the sensory and motor nerve endings were well preserved.Temporary Research Fellow the Rotterdam Centre for Rheumatic Disease
Present address: Division of Pathology, Department of Obstetrics and Gynaecology, University of Chicago, Chicago, Illinois 60637, USA 相似文献
72.
Mihaela Humar M. Kordaš Živa Melik 《Pflügers Archiv : European journal of physiology》1980,386(1):67-70
Papaine is known to detach cholinesterases from the synaptic cleft. It could be expected that this would result in an increase of the amplitude and half-time of the end-plate current. Thus, the effect of papaine on the end-plate current should be similar to the effect of anticholinesterase methanesulfonyl-fluoride.The end-plate current was recorded in frog skeletal muscle at various levels of membrane potential, before and after papaine was added to the bath.The effect of papaine was an increase of the half-time of the end-plate current, similarly as after treatment of the muscle by methanesulfonylfluoride.It seems that both papaine and methanesulfonyl-fluoride have a similar mechanism of action. In either experimental condition hydrolysis of transmitter is decreased or abolished, which results in an increase of the half-time of the end-plate current.This work was supported by the Research Community of Slovenia 相似文献
73.
Effects of knee joint angles and fatigue on the neuromuscular control of vastus medialis oblique and vastus lateralis muscle in humans 总被引:1,自引:0,他引:1
The effects of different knee joint angles and fatigue on the neuromuscular control of the vastus medialis oblique (VMO)
and vastus lateralis (VL) muscles were investigated in 17 (11 men, 6 women) young subjects. The electromyogram (EMG) activities
and the force generation capacities were monitored before and after a fatigue protocol at three different knee joint angles,
90°, 150°, 175° of knee extension, on three occasions. In response to randomly triggered light signals, the subjects performed
three isometric maximal voluntary contraction (IMVC) that lasted for 4 to 8 s. This was then followed by the fatigue protocol
which consisted of six bursts of contractions fixed at 30 s on and 10 s off. Immediately after the exercise to fatigue, the
subjects performed another three IMVC in response to the light signals. Repeated measures ANOVA were performed to examine
the effects of fatigue at these three positions on the electromechanical delay (EMD), median frequency (f
med), peak force (F
peak) and root mean square (rms)-EMG:F
peak quotient of VMO and VL. The results revealed a significant effect of the three knee joint angles on the EMD before the fatigue
(P < 0.05). The fatigue protocol induced a significant decrease in F
peak at all the three positions (P < 0.01). However, the fatigue induced a significant decrease of f
med at only 90° and 150° of knee extension (P < 0.01). This occurred in parallel with the lengthening of EMD at these two joint angles (P < 0.01 and P < 0.05). The effects of fatigue on the f
med and EMD were not significant between VMO and VL at all three angles. The insignificant difference in f
med and EMD between VMO and VL at the three knee positions before and after fatigue indicated that no preferential onset activation
between VMO and VL had occurred.
Accepted: 1 September 2000 相似文献
74.
Simultaneous electrical stimulation of tissue with the measurement of blood flow using an electromagnetic flowmeter system
almost invariably results in large flow measurement inaccuracies. These inaccuracies are because the electrical energy from
stimulating artefacts is amplified along with the flow signals. The paper describes the building and use of an inexpensive
circuit to remove stimulation artefacts from electromagnetic flow measurements. 相似文献
75.
Toshikazu Kubo Tetsushi Minamitani Hiroyasu Nishikawa Yasusuke Hirasawa 《Pathophysiology》1998,4(4):303-308
Energy metabolism and contractility of rat’s femoral triceps muscles were investigated by varying blood flow levels with ligation of the femoral artery. The triceps were stimulated electrically to produce equivalent conditions as exercise loading, and phosphorus nuclear magnetic resonance (31P-NMR) spectra and muscle tension levels were monitored. The ratio of inorganic phosphate (Pi) to ‘Pi+phosphocreatine (PCr)’, i.e. Pi/(Pi+PCr), was obtained from 31P-NMR spectra. This ratio was related to the reduction of blood flow ratio (BFR) during and after the stimulation period, whereas before starting the stimulation, there was no significant correlation. These findings indicate: (i) muscle energy metabolism during decreased blood flow is influenced by the stimulation (loading) given to the muscle; and (ii) changes of muscle energy metabolism due to decreased muscle blood flow during the loading is evaluable by measuring 31P-NMR spectra. Muscle tension reached the plateau 8 min after starting the stimulation, regardless of BFR, but muscle tension ratio decreased as BFR became lower. This indicates that decreased blood flow diminishes muscle contractility, and then lowers muscle function levels. Our findings indicate that muscle blood flow plays an important role in muscle function, and blood flow and muscle function levels are evaluable by measuring 31P-NMR spectra of the muscle. 相似文献
76.
E. Knyihár-Csillik János Tajti Mohtasham Samsam Gyula Sáry Péter Buzás László Vécsei 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,118(1):111-114
Electrical stimulation of the Gasserian ganglion resulted in partial depletion of calcitonin gene-related peptide (CGRP) from
ipsilateral central terminals of pseudounipolar primary sensory ganglion cells. Affected terminals exhibit decreased CGRP
immunoreactivity as shown by cytophotometric densitomery of the caudal trigeminal nucleus. The decrease in CGRP immunoreactivity
is statistically significant only in the medial one-third of the caudal trigeminal nucleus. Since earlier studies have shown
that electrical stimulation of the Gasserian ganglion induces first accumulation then depletion of CGRP from perivascular
sensory terminals in the dura mater, the present experiments suggest that CGRP is depleted also from central terminals of
primary sensory trigeminal neurons, which might be of importance in the pathogenesis of migraine headache.
Received: 18 December 1996 / Accepted: 26 June 1997 相似文献
77.
K.-M. Zhang Ping Hu Shang-Wu Wang Leon D. Wright Andrew S. Wechsler John A. Spratt F. N. Briggs 《Pflügers Archiv : European journal of physiology》1998,435(4):511-517
Chronic administration of salbutamol induced expression of hybrid fibers in canine skeletal muscles. Fast-twitch fibers expressed
SERCA2a (the slow-twitch isoform of sarcoplasmic reticulum Ca2+-ATPase) and slow-twitch fibers expressed SERCA1 (the fast-twitch isoform of the Ca2+-ATPase). The proportion of fibers that became hybrid increased from a small percentage in the control muscles to 30% in the
predominantly fast-twitch latissimus dorsi and to 45% in the predominantly slow-twitch vastus intermedius. In contrast to
this response by the SERCA genes the phospholamban gene response was muscle specific. The fraction of fibers that expressed
phospholamban decreased slightly in the latissimus dorsi while increasing moderately in the vastus intermedius. The effects
of chronic neurostimulation of the latissimus dorsi on SERCA1, SERCA2a and phospholamban levels were mostly blocked by salbutamol.
While 100% of fibers from neurostimulated muscles expressed phospholamban, only 51% of the fibers from the neurostimulated
and salbutamol-treated muscles expressed it. In the neurostimulated muscle, very few muscle fibers expressed SERCA1a while
61% of the fibers that received salbutamol expressed it, albeit as hybrid fibers. The levels of SERCA2a in response to these
interventions were just the opposite. In the neurostimulated muscle 37.5% of fibers were hybrid and 62.5% expressed SERCA2a
only. With co-administration of neurostimulation and salbutamol, 61.3% of fibers were hybrid and 38.7% expressed SERCA2a only.
Received: 4 July 1997 / Received after revision: 16 October 1997 / Accepted: 30 October 1997 相似文献
78.
为了研究性能更好的EIT图像重构算法,我们对基于敏感性定理的EIT图像重构算法进行了计算机仿真研究,并与几种常用图像重构算法进行比较,提出对基于敏感性定理的EIT图像重构算法的改进措施。 相似文献
79.
神经肌肉电刺激模拟肌肉力量训练的生物力学研究 总被引:1,自引:0,他引:1
李建设 《生物医学工程学杂志》2002,19(3):395-397
基于对电刺激模拟肌肉力量训练的理论与实践研究,结果表明:神经肌肉电刺激(NMES)的训练效果显著优于肌肉直接电刺激(MES),肌肉力量素质的增长与电刺激方式和刺激源的电特性有关;NMES能以较低的体能消耗完成肌肉力量的训练,适合作为常规训练前,中、后的辅助训练手段,NMES模拟肌肉力量训练的方式能满足肌肉功能群协调能力的同步发展。 相似文献
80.
Patrick Feiereisen Jacques Duchateau K. Hainaut 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1997,114(1):117-123
The recruitment order of motor units (MU) was compared during voluntary and electrically induced contractions. With the use
of spike-triggered averaging, a total of 302 MUs with recruitment thresholds ranging from 1% to 88% of maximal voluntary contraction
were recorded in the human tibialis anterior muscle in five subjects. The mean (±SD) MU force was 98.3±93.3 mN (mean torque
16.8±15.9 mNm) and the mean contraction time (CT) 46.2±12.7 ms. The correlation coefficients (r) between MU twitch force and CT versus the recruitment threshold in voluntary contractions were +0.68 and –0.38 (P<0.001), respectively. In voluntary contractions, MUs were recruited in order of increasing size except for only 6% of the
cases; whereas, during transcutaneous electrical stimulation (ES) at the muscle motor point, MU pairs showed a reversal of
recruitment order in 28% and 35% of the observations, respectively, when the pulse durations were 1.0 ms or 0.1 ms. This recruitment
reversal during ES was not related to the magnitude of the difference in voluntary recruitment thresholds between MUs. It
is concluded that if the reversal of MU recruitment observed during ES is biophysically controlled by differences in their
nerve axon input impedance, in percutaneous stimulation at the motor point, other factors such as the size and the morphological
organisation of the axonal branches can also influence the order of activation.
Received: 24 May 1996 / Accepted: 30 September 1996 相似文献