著者

Yamamoto Tetsuo Kinoshita Manabu Shinomiya Nariyoshi HIROI Sadayuki SUGASAWA Hidekazu MATSUSHITA Yoshitaro MAJIMA Takashi SAITOH Daizoh SEKI Shuhji

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of radiation research (ISSN:04493060)

巻号頁・発行日

vol.51, no.2, pp.145-156, 2010-03-16

被引用文献数

38

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While bone marrow or stem cell transplantation can rescue bone marrow aplasia in patients accidentally exposed to a lethal radiation dose, radiation-induced irreversible gastrointestinal damage (GI syndrome) is fatal. We investigated the effects of ascorbic acid on radiation-induced GI syndrome in mice. Ascorbic acid (150 mg/kg/day) was orally administered to mice for 3 days, and then the mice underwent whole body irradiation (WBI). Bone marrow transplantation (BMT) 24 h after irradiation rescued mice receiving a WBI dose of less than 12 Gy. No mice receiving 14 Gy-WBI survived, because of radiation-induced GI syndrome, even if they received BMT. However, pretreatment with ascorbic acid significantly suppressed radiation-induced DNA damage in the crypt cells and prevented denudation of intestinal mucosa; therefore, ascorbic acid in combination with BMT rescued mice after 14 Gy-WBI. DNA microarray analysis demonstrated that irradiation up-regulated expressions of apoptosis-related genes in the small intestine, including those related to the caspase-9-mediated intrinsic pathway as well as the caspase-8-mediated extrinsic pathway, and down-regulated expressions of these genes in ascorbic acid-pretreated mice. Thus, pretreatment with ascorbic acid may effectively prevent radiation-induced GI syndrome.

著者

Kimura Hiroshi Fukagawa Misato Tamura Motohide KOBAYASHI Hiroshi YAMAMOTO Tetsuo ISHII Miki SUTO Hiroshi

出版者

Terra Scientific Pub. Co.

雑誌

Earth, planets and space (ISSN:13438832)

巻号頁・発行日

vol.62, no.1, pp.111-116, 2010-01-01

参考文献数

37

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We report near-infrared imaging observations of the β Pic dust disk, from which we infer the orbital architecture of planetesimal belts that remain near mean motion resonances (MMRs) with a planet at 62 AU. Our results reveal that one of the previously identified planetesimal belts lies in the 2/3 MMR with the planet, similar to the resonant relation between Plutinos and Neptune. We suggest that all the previously reported planetesimal belts are located near the 2/3 MMRs of four planets whose spatial arrangements make a similar figure of Jupiter, Saturn, Uranus, and Neptune. This implies that the Solar System is a prototype of planetary systems around main-sequence stars in terms of planets' configuration, as expected from planet formation theories.