@misc{oai:repo.qst.go.jp:00068245,
 author = {Kakinuma, Shizuko and Amasaki, Yoshiko and Yamauchi, Kazumi and Nishimura, Mayumi and Imaoka, Tatsuhiko and Shimada, Yoshiya and 柿沼 志津子 and 甘崎 佳子 and 山内 一己 and 西村 まゆみ and 今岡 達彦 and 島田 義也},
 month = {Nov},
 note = {Radiation carcinogenesis in human is considered as a result of the combined effect of radiation and environment factors. We previously showed that smaller doses of X-rays reduced the incidence of TL induced by N-ethyl-N-nitrosourea (ENU), while large doses of X-rays increased and accelerated the TL development in a synergistic manner. This indicates the mode of combined effect is dependent upon the dose of X-rays. In this study, we aimed to determine the mode of combined effect on tumors other than TL and life-span (LS) shortening.
B6C3F1 mice (4-week-old female) were irradiated with X-rays (0.2 - 2.0 Gy a week x 4 times) or treated with ENU for 4weeks (50 - 400 ppm in drinking water) from 8-week-old. For combined treatment, the mice were irradiated with X-rays (0.2 - 1.0 Gy a week x 4 times) and then treated with ENU (50 - 200 ppm).
The LS after combined exposure (0.2/0.4 Gy X-rays with 200 ppm ENU) was much longer than that of ENU treatment alone, suggesting small dose of X-rays has antagonistic function. Contrary to the results of TL, incidence of tumors of lung, liver and ovaries increased more than additively after the combination of ENU with X-rays even at small doses. Thus, the role of X-rays in combined exposure was dependent not only the dose used but also the tissues examined., 第48回日本放射線影響学会／第1回アジア放射線研究会議},
 title = {Combined effects of X-rays and N-ethyl-N-nitrosourea on carcinogenesis and life-span-shortening in B6C3F1 mice},
 year = {2005}
}