The purpose of this study was to examine whether oxygen supply is critical to the generation of fibrillation potentials in the denervated rat muscle. Twenty-eight male Wistar rats each weighing between 200 and 352 grams were used. All procedures were performed under general anesthesia with thiopental sodium (80mg/kg). Denervated muscle was prepared by resection of the left sciatic nerve in the upper thigh region. A needle electromyogram was recorded in the left extensor digitorum longus muscle one week after resection of the nerve. Fibrillation potentials were observed in all rats. The effects of arrested circulation and hypoxia induced by controlled ventilation on fibrillation potentials were examined. Fibrillation potentials first transiently increased, then decreased exponentially and disappeared after the circulation had been arrested by ligating the abdominal aorta and inferior vena cava. Fibrillation potentials recovered rapidly after renewal of circulation. In other experiments in which blood flow was replaced by infusion of a physiologic solution via the abdominal aorta, fibrillation potentials transiently increased, then decreased exponentially, and finally disappeared during irrigation. The interval between circulatory arrest and disappearance of the fibrillation potentials was 406±171sec (mean±standard deviation, n=14), and it showed no statistically significant difference from the interval (454±270sec) between the start of irrigation and disappearance of the fibrillation potentials. Secondly, the fibrillation potential firing rate always decreased in hypoxia due to low-oxygen ventilation (n=14). The firing rate during hypoxia (partial pressure of arterial blood oxygen: Pao₂=39.0±10.1torr) averaged 40.1% of the firing rate during room-air ventilation (Pao₂=88.6±5.7torr). According to these results, it can be concluded that the generation of fibrillation potentials depends on oxygen supply.

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Restoration and improvement of the walking capability is one of the most important tasks in the rehabilitation of hemiplegic patients secondary to cerebro-vascular-accidents. In the approach for this respect, the clinical efficacy of surgical procedure is generally recognized as well as the case of treatment with ankle-foot-orthoses (AFOs). In this study, the effectiveness of the surgical procedure was objectively evaluated by applying gait analysis techniques upto one year after operation, and was compared to that of the treatment by AFOs. Furthermore, the postoperative result upto two years was investigated.
Subjects covered in this study were 25 operative patients.
Patients were divided into four classes with respect to surgical indication. Class I: unable to walk even with an AFO, class II: able to walk with a conventional double-upright AFO, class III: able to walk with a plastic AFO; and class IV: able to walk without AFO. Various operative methods were used as combined. They included lengthening of the tendon Achilles, transfer of the posterior tibial tendon, and release of the digitalis flexor tendons etc.
Quantitative analysis was made primarily by temporal-distance factors, the accelerometer indices developed by Yamazaki, and the foot-force based indices developed by Miyazaki. In patients categorized as class I and II, the foot contact pattern was remarkably improved. The operative patients categorized as class III gained similar values in gait speed, step length, cadence, symmetry and stability to those patients treated with AFOs. Furthermore the indices of transfer, limb support and foot contact, all for the involved side, derived from the foot-force data showed gradual and consistent improvement. In patients categorized as class IV, the indices of transfer, limb support and foot contact were improved.
Thus, it was found that the effectiveness of this surgical procedure was not significantly superior to that of AFOs, still 20 (90.9%) of 22 operative cases reached the level forecasted before the operation. Even to the postoperative period upto two years, in 16 (88.9%) of 18 operative cases the effectiveness was still maintained.
Therefore, it is concluded that the operation is more suited than AFOs for the japanese life style, in which footwear is not used inside the house.

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[in Japanese]

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