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47 results on '"Hara, Toshiko"'

20. Effects of short-term food deprivation on sweating and shivering thresholds

Author

Hara, Toshiko, Maruyama, Megumi, Hashimoto, Tatsuya, Matsuzaki, kentaro, Hashimoto, Michio, Katakura, Masanori, and Shido, Osamu

Abstract

Starvation is known to lower the threshold core temperature for thermogenesis and then body core temperature in animals. However, little attention has been paid to the effects of food deprivation on heat loss mechanisms, especially in humans. We therefore determined the threshold temperatures for sweating and also shivering in humans after a 24-hour starvation. The subjects rested on a chair at an ambient temperature of 26℃ and relative humidity of 45%. Their rectal temperature (Tre) and skin temperatures at 7 body sites were continuously measured. Then, they were warmed or cooled by bathing both legs in warm (42℃) or cold water (15℃), respectively. Tre and skin temperatures at the onsets for thermally-induced sweating and shivering were determined, and threshold mean body temperatures (Tb) for them were calculated. The 24-hour food deprivation significantly lowered the threshold Tb for shivering, but did not affect the sweating thresho]d Tb. The results suggest that, in humans, the interthreshold zone is widened by food deprivation solely due to a decrease in the threshold for the activation of thermogenesis.

Published
2007

21. Dietary effects of docosahexaenoic acid on spatial cognition learning ability in rats fed N-3 fatty acid-adequate diet

Author

Tanabe, Yoko, Hashimoto, Michio, Haque, Abdul Md., Sugioka, Kozo, Katakura, Masanori, Hara, Toshiko, and Shido, Osamu

Abstract

Twenty-two 5-week-old male Wistar rats fed an n-3 fatty acid-adequate diet were supplemented with docosahexaenoic acid (DHA) administered perorally for 14 weeks. Six weeks after the start of the administralion, the rats were for 5 weeks trained to acquire a reward at the end of each of 4 arms of an 8-arm radial maze. The retention test interposed with a delayed task (20-min interval after acquiring the first 2 rewards) was then given to each rat to determine spatial working memory retention DHA administration reduced the number of working memory errors after the 20-min interval in the retention test and tended to induce an increase in the DHA/arachidonic acid ratio in the hippocampus, indicating that chronic administration of DHA to rats fed an n-3 fatty acid-adequate diet is conducive to the improvement of working memory-related learning abiiity.

Published
2005

37. Biodisposition and metabolism of [18F]fluorocholine in 9L glioma cells and 9L glioma-bearing fisher rats.

Author

Bansal, Aditya, Shuyan, Wang, Hara, Toshiko, Harris, Robert, and DeGrado, Timothy

Subjects
CHOLINE, GLIOMAS, DIAGNOSTIC imaging, POSITRON emission tomography, TUMORS, CANCER cells
Abstract

[18F]Fluorocholine ([18F]FCH) was developed as an analog of [11C]choline for tumor imaging; however, its metabolic handling remains ill defined. In this study, the metabolism of [18F]FCH is evaluated in cultured 9L glioma cells and Fisher 344 rats bearing 9L glioma tumors. 9L glioma cells were incubated with [18F]FCH and [14C]choline under normoxic and hypoxic (1% O2) conditions and analyzed for metabolic fate. [18F]FCH and [14C]choline kinetics and metabolism were studied in Fisher 344 rats bearing subcutaneous 9L tumors. [18F]FCH and [14C]choline were similarly metabolized in 9L cells in both normoxic and hypoxic conditions over a 2-h incubation period. In normoxia, radioactivity was predominantly in phosphorylated form for both tracers after 5-min incubation. In hypoxia, the tracers remained mainly in nonmetabolized form at early timepoints (<20 min). Slow dephosphorylation of intracellular [18F]phosphofluorocholine (0.043–0.060 min−1) and [14C]phosphocholine (0.072–0.088 min−1) was evidenced via efflux measurements. In rat, both [18F]FCH and [14C]choline showed high renal and hepatic uptake. Blood clearance of both tracers was rapid with oxidative metabolites, [18F]fluorobetaine and [14C]betaine, representing the majority of radiolabel in plasma after 5 min postinjection. Oxidation (in liver) and lipid incorporation (in lung) were somewhat slower for [18F]FCH relative to [14C]choline. The majority of radiolabel in hypoxic subcutaneous tumor, as in hypoxic cultured 9L cells, was found as nonmetabolized [18F]FCH and [14C]choline. [18F]FCH mimics choline uptake and metabolism by 9L glioma cells and tumors. However, subtle changes in biodistribution, oxidative metabolism, dephosphorylation, lipid incorporation, and renal excretion show moderate effects of the presence of the radiofluorine atom in [18F]FCH. The decrease in phosphorylation of exogenous choline by cancer cells should be considered in interpretation of positron emission tomography images in characteristically hypoxic tumors. [ABSTRACT FROM AUTHOR]

Published
2008
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41. Caspase-Dependent Cytosolic Release of Cytochrome cand Membrane Translocation of Bax in p53-Induced Apoptosis

Author

Feng Gao, Chong, Ren, Shuo, Zhang, Lilin, Nakajima, Takuma, Ichinose, Shizuko, Hara, Toshiko, Koike, Katsuro, and Tsuchida, Nobuo

Abstract

Activation of p53 induces apoptosis in various cell types. However, the mechanism by which p53 induces apoptosis is still unclear. We reported previously that the activation of a temperature-sensitive mutant p53 (p53138Val) induced activation of caspase 3 and apoptosis in Jurkat cells. To elucidate the pathway linking p53 and downstream caspases, we examined the activation of caspases 8 and 9 in apoptotic cells. The results showed that both caspases were activated during apoptosis as judged by the appearance of cleavage products from procaspases and the caspase activities to cleave specific fluorogenic substrates. The significant inhibition of apoptosis by a tetrapeptide inhibitor of caspase 8 and caspase 9 suggested that both caspases are required for apoptosis induction. In addition, the membrane translocation of Bax and cytosolic release of cytochrome c,but not loss of mitochondrial membrane potential, were detected at an early stage of apoptosis. Moreover, Bax translocation, cytochrome crelease, and caspase 9 activation were blocked by the broad-spectrum caspase inhibitor, Z-VAD-fmk and the caspase 8-preferential inhibitor, Ac-IETD-CHO, suggesting that the mitochondria might participate in apoptosis by amplifying the upstream death signals. In conclusion, our results indicated that activation of caspase 8 or other caspase(s) by p53 triggered the membrane translocation of Bax and cytosolic release of cytochrome c,which might amplify the apoptotic signal by activating caspase 9 and its downstream caspases.

Published
2001
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45. AMD, Fujitsu give flash memory joint venture new legs for Intel run.

Author

Hara, Toshiko and LaPedus, Mark

Subjects
*FLASH memory
Abstract

Reports that the merged flash memory operations of Advanced Micro Devices Inc. and Fujitsu Ltd. is aiming to outperform Intel Corp. and Samsung Electronics Co. Ltd. Terms and conditions of the joint venture; Combined finances and market share.

Published
2003

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