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.
Adolescence ; Biopsy ; Case Report ; Female ; Human ; Microscopy, Electron ; Mitochondria/ultrastructure ; Mitochondria/pathology ; Muscle, Skeletal/ultrastructure ; Muscle, Skeletal/pathology ; Muscle, Skeletal/enzymology ; Myasthenia Gravis/pathology* ; Myofibrils/ultrastructure ; Myofibrils/pathology ; Myosin ATPase/analysis ; Neuromuscular Junction/ultrastructure* ; Neuromuscular Junction/pathology*

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.
Adolescence ; Biopsy ; Case Report ; Female ; Human ; Microscopy, Electron ; Mitochondria/ultrastructure ; Mitochondria/pathology ; Muscle, Skeletal/ultrastructure ; Muscle, Skeletal/pathology ; Muscle, Skeletal/enzymology ; Myasthenia Gravis/pathology* ; Myofibrils/ultrastructure ; Myofibrils/pathology ; Myosin ATPase/analysis ; Neuromuscular Junction/ultrastructure* ; Neuromuscular Junction/pathology*

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.
Animals ; Hindlimb Suspension ; Lactic Acid/metabolism ; Microscopy, Electron ; Muscle Contraction/*physiology ; Muscle Fatigue/*physiology ; Muscle, Skeletal/cytology/*physiology ; Myofibrils/ultrastructure ; Rats ; Rats, Sprague-Dawley ; Research Support, Non-U.S. Gov't ; Weight-Bearing/physiology

OBJECTIVETo investigate effects of Shenfu injection on the concentrations of plasma tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), activity of Nuclear Factor kappa B (NF-kappaB) and heart tissue ultrastructure during myocardial ischemia/reperfusion (I/R) injury in rats and its potential mechanism.

METHODSMyocardial ischemia/reperfusion (I/R) was produced by ligation and release of the left anterior descending coronary artery. Ischemia lasted for 30 min and reperfusion for 60 min. Twenty-four healthy male SD rats weighing 230-280 g were randomly divided into three groups (n = 8, each): Group I (Sham-operation group); Group II (I/R group); Group III (Shenfu group), in which Shenfu injection (10 ml/kg) was intraperitoneally injected 30 min before ischemia in animals with I/R. The plasma concentrations of IL-6 and TNF-alpha were measured by ELISA, and the heart was harvested for determination of NF-kappaB levels by Ecl-western blot analysis. Electron microscopy was used to study its ultrastructure.

RESULTSAfter reperfusion, NF-kappaB binding activity in myocardial nuclei and the plasma concentrations of IL-6 and TNF-alpha were significantly increased in Group II, compared with Group I (P < 0.01), and they were markedly reduced in Group III, compared with Group II (P < 0.01). In addition, electron microscopic examination showed more serious injury of the myocardium ultrastructure in Group II, while in Group III the myocardial ultrastructure was similar to normal state.

CONCLUSIONSShenfu injection inhibits NF-kappaB activity in I/R myocardium and leads to down-regulation of proinflammatory cytokine expression, which might be one of the molecular mechanisms of Shenfu injection in cardioprotection.

Animals ; Drugs, Chinese Herbal ; pharmacology ; Interleukin-6 ; blood ; Male ; Myocardial Reperfusion Injury ; drug therapy ; metabolism ; pathology ; Myofibrils ; ultrastructure ; NF-kappa B ; antagonists & inhibitors ; Rats ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha ; analysis