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1.
Yonsei Medical Journal ; : 690-702, 2004.
Artigo em Inglês | WPRIM | ID: wpr-206354

RESUMO

In order to elucidate muscle functional changes by acute reloading, contractile and fatigue properties of the rat soleus muscle were investigated at three weeks of hindlimb suspension and the following 1 hr, 5 hr, 1 d, and 2 weeks of reloading. Compared to age-matched controls, three weeks of unloading caused significant changes in myofibrillar alignments, muscle mass relative to body mass (-43%), normalized tension (-35%), shortening velocity (+143%), and response times. Further significant changes were not observed during early reloading, because the transitional reverse process was gradual rather than abrupt. Although most of the muscle properties returned to the control level after two weeks of reloading, full recovery of the tissue would require more than the two-week period. Delayed recovery due to factors such as myofibrillar arrangement and fatigue resistance was apparent, which should be considered for rehabilitation after a long-term spaceflight or bed-rest.


Assuntos
Animais , Ratos , Elevação dos Membros Posteriores , Ácido Láctico/metabolismo , Microscopia Eletrônica , Contração Muscular/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/citologia , Miofibrilas/ultraestrutura , Ratos Sprague-Dawley , Suporte de Carga/fisiologia
2.
Journal of Korean Medical Science ; : 251-254, 2000.
Artigo em Inglês | WPRIM | ID: wpr-140415

RESUMO

Although light microscopic features of muscle are not pathognomonic in most cases of myasthenia gravis (MG), careful examination of neuromuscular junction by electron microscopy (EM) can reveal important clues for this disease. We report here a case of MG confirmed by EM study to emphasize that tissue diagnosis is still the best adjuvant to confirm the diagnosis. An 18-year-old female visited our hospital complaining of progressive muscle weakness for 3 years. She had difficulty in running, going upstairs and doing routine activities. Symptoms were aggravated with continuous work and resolved after rest. She had weakness of bilateral masseter and facial muscles and proximal portions of extremities without definite diurnal variation. Electromyography showed myopathic changes in proximal muscles of extremities. MG was considered but tensilon test was equivocal. Repetitive nerve stimulation tests revealed 20-30 percent decrease in responses to low and high rate stimulation. Muscle biopsy revealed selective type 2 atrophy. Ultrastructurally, abnormalities of neuromuscular junctions, i.e., wide primary synaptic cleft, and wide and shallow secondary synaptic clefts with mild myopathic features were present. These findings were pathognomonic for MG. Later, her symptoms were improved completely 3 months after thymectomy. The histologic finding of thymus was follicular hyperplasia.


Assuntos
Feminino , Humanos , Adolescente , Biópsia , Microscopia Eletrônica , Mitocôndrias/ultraestrutura , Mitocôndrias/patologia , Músculo Esquelético/ultraestrutura , Músculo Esquelético/patologia , Músculo Esquelético/enzimologia , Miastenia Gravis/patologia , Miofibrilas/ultraestrutura , Miofibrilas/patologia , Miosinas/análise , Junção Neuromuscular/ultraestrutura , Junção Neuromuscular/patologia
3.
Journal of Korean Medical Science ; : 251-254, 2000.
Artigo em Inglês | WPRIM | ID: wpr-140414

RESUMO

Although light microscopic features of muscle are not pathognomonic in most cases of myasthenia gravis (MG), careful examination of neuromuscular junction by electron microscopy (EM) can reveal important clues for this disease. We report here a case of MG confirmed by EM study to emphasize that tissue diagnosis is still the best adjuvant to confirm the diagnosis. An 18-year-old female visited our hospital complaining of progressive muscle weakness for 3 years. She had difficulty in running, going upstairs and doing routine activities. Symptoms were aggravated with continuous work and resolved after rest. She had weakness of bilateral masseter and facial muscles and proximal portions of extremities without definite diurnal variation. Electromyography showed myopathic changes in proximal muscles of extremities. MG was considered but tensilon test was equivocal. Repetitive nerve stimulation tests revealed 20-30 percent decrease in responses to low and high rate stimulation. Muscle biopsy revealed selective type 2 atrophy. Ultrastructurally, abnormalities of neuromuscular junctions, i.e., wide primary synaptic cleft, and wide and shallow secondary synaptic clefts with mild myopathic features were present. These findings were pathognomonic for MG. Later, her symptoms were improved completely 3 months after thymectomy. The histologic finding of thymus was follicular hyperplasia.


Assuntos
Feminino , Humanos , Adolescente , Biópsia , Microscopia Eletrônica , Mitocôndrias/ultraestrutura , Mitocôndrias/patologia , Músculo Esquelético/ultraestrutura , Músculo Esquelético/patologia , Músculo Esquelético/enzimologia , Miastenia Gravis/patologia , Miofibrilas/ultraestrutura , Miofibrilas/patologia , Miosinas/análise , Junção Neuromuscular/ultraestrutura , Junção Neuromuscular/patologia
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