Katsuya Kawanishi

Mapping of redox status in a brain‐disease mouse model by three‐dimensional EPR imaging

Electron paramagnetic resonance imaging using nitroxides is a powerful method for visualizing the redox status modulated by oxidative stress in vivo. Typically, however, data acquisition times have been too slow to obtain a sufficient number of projections for three‐dimensional images, when using continuous wave‐electron paramagnetic resonance imager in small rodents, using nitroxides with comparatively short T2 and a half‐life values. Because of improvements in imagers that enable rapid data‐acquisition, the feasibility of three‐dimensional electron paramagnetic resonance imaging with good quality in mice was tested with nitroxides. Three‐dimensional images of mice were obtained at an interval of 15 sec under field scanning of 0.3 sec and with 46 projections in the case of strong electron paramagnetic resonance signals. Three‐dimensional electron paramagnetic resonance images of a blood brain barrier‐permeable nitroxide, 3‐hydroxymethyl‐2,2,5,5‐tetramethylpyrrolidine‐1‐oxyl, in the mouse head clearly showed that 3‐hydroxymethyl‐2,2,5,5‐tetramethylpyrrolidine‐1‐oxyl was distributed within brain tissues, and this was confirmed by MRI observations. Based on the pharmacokinetics of nitroxides in mice, half‐life mapping was demonstrated in an ischemia‐reperfusion model mouse brain. Inhomogeneous half‐lives were clearly mapped pixel‐by‐pixel in mouse head under oxidative stress by the improved continuous wave‐electron paramagnetic resonance imager noninvasively. Magn Reson Med, 2010.

Effect of Mastication on Functional Recoveries after Permanent Middle Cerebral Artery Occlusion in Rats

OBJECTIVES We evaluated whether solid feed is more effective for functional recoveries than liquid feed in rats with ischemic brain injury after permanent middle cerebral artery occlusion (MCAO). METHODS A total of 36 male Wistar/ST rats were subjected to MCAO or sham surgery. After MCAO or sham surgery, all rats were provided liquid feed for 14 days. Then, all rats were divided into 3 groups: the solid feeding group, the liquid feeding group, and the solid feeding group of sham. Effect of mastication on functional recoveries after permanent MCAO in rats was evaluated by the limb placement test and Morris water maze (MWM) task. RESULTS After surgery, limb placement test scores were equal in both MCAO groups. In the acquisition trials of MWM task, statistically significant differences in escape latency were observed between the liquid feeding group and sham groups at all days, and between the solid feeding group and sham groups at days 3 and 4 of the trials. In the probe trial, statistically significant differences in time spent were observed between the liquid feeding group and sham group. On day 5 of acquisition trials, the time spent in the periphery of the pool in MWM task was significantly different among the 3 groups. CONCLUSION This study suggested that solid diet mastication could be effective for the rehabilitation of sensorimotor and learning/memory dysfunction induced by cerebral infarction.