We describe the set-up for an electrical muscle stimulation device based on near-infrared spectroscopy (NIRS), designed for use as a brain-computer interface (BCI). Employing multi-channel NIRS, we measured evoked cerebral blood oxygenation (CBO) responses during real motor tasks and motor-imagery tasks. When a supra-threshold increase in oxyhemoglobin concentration was detected, electrical stimulation (50 Hz) of the biceps brachii muscle was applied to the side contralateral to the hand grasping task or ipsilateral to the motor-imagery task. We observed relatively stable and reproducible CBO responses during real motor tasks with an average accuracy of 100%, and during motor imagery tasks with an average accuracy of 61.5%. Flexion movement of the arm was evoked in all volunteers in association with electrical muscle stimulation and no adverse effects were noted. These findings suggest that application of the electrical muscle stimulation system based on a NIRS-BCI is non-invasive and safe, and may be useful for the physical training of disabled patients.
In order to obtain an insight into the mechanism of experimentally induced redifferentiation of cancer cells, changes in negative charge of the cell membrane were examined by cytopherometry following in vitro exposure of the cancer cells to non-radioactive gallium. Reduction of the negative charge was observed at 24 hr and later. The gallium ions must have neutralized the negative charge of the cancer cell membrane to the normal range. This event may contribute in some way to cancer cell redifferentiation. cancer redifferentiation ; negative charge of cell membrane ; gallium citrate Induction of redifferentiation of cancer cells can be of some help for the treatment of cancer. We have found that gallium ions can induce redifferentiation of experimental tumors in vitro and in vivo (Awano and Matsuzawa 1977 ;Okuyama et al. 1978b). The present study was undertaken to obtain an insight into the mechanism of such redifferentiation. FM3A undifferentiated mammary adenocarcinoma cells arising in C3H mouse were cultured in Eagle's MEM medium deprived of Ca2+ and supplemented with calf serum to 10%. The cultured cells were washed with 1/15 M phosphate buffer containing glucose at 5.4%. Cytopherometry was carried out using rat red cells for reference. Negative charge of the cell membrane was expressed in terms of electrophoretic mobility (,am•sec-1•V-1•cm) as described elsewhere (Yamada 1969). Metallic gallium was dissolved in conc. HCI and conc. HNO3, and the stock solution of gallium citrate was prepared and refrigerated until use.Although the surviving fraction of the cultured cells decreased progressively with time at a concentration of 1.4 mg/ml of gallium, it remained within the range of marginal cell kill at a concentration of 0.7 mg/ml (Fig. 1). At the lower dose level (0.7 mg/ml), the proportion of dead cells to the viable ones was 3 to 5%, while it reached up to 30% at 48 hr at the higher dose level (1.4 mg/ml).Negative charge of the cell was rather stable to the gallium treatment. Its reduction
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