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Mammary carcinogenesis after prepubertal radiation exposure in rats: effect of age at exposure to gamma-rays, 1-methyl-1-nitrosourea and their combination
https://repo.qst.go.jp/records/68536
https://repo.qst.go.jp/records/68536701dfb1f-bf1d-421d-9106-6726e01dde6d
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2006-06-26 | |||||
| タイトル | ||||||
| タイトル | Mammary carcinogenesis after prepubertal radiation exposure in rats: effect of age at exposure to gamma-rays, 1-methyl-1-nitrosourea and their combination | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_c94f | |||||
| 資源タイプ | conference object | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Imaoka, Tatsuhiko
× Imaoka, Tatsuhiko× Nishimura, Mayumi× Kakinuma, Shizuko× Ohmachi, Yasushi× Nishimura, Yukiko× Shimada, Yoshiya× 今岡 達彦× 西村 まゆみ× 柿沼 志津子× 大町 康× 西村 由希子× 島田 義也 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | [Objective] Epidemiology on A-bomb survivors has clarified that childhood exposure confers high breast cancer risk. But the underlying mechanism is unclear. Using Sprague-Dawley rats, we attempted to verify if childhood exposure (1) results in increased development of mammary cancer and (2) affects susceptibility to a subsequent carcinogen. <br> [Methods] Rats were (1) γ-irradiated (2 Gy) or treated with methylnitrosourea (MNU; 20 mg/kg, i.p.) at 3 or 7 weeks (w) of age; or (2) irradiated at 3 w and then MNU-treated at either 3 or 7 w. They were observed until 50 w. <br> [Results] (1) Spontaneous palpable mammary cancer multiplicity was 0.07 ± 0.04 (tumors/rat, mean ± SEM). Rats irradiated at 3 w developed significantly less tumors than those irradiated at 7 w (0.28 ± 0.11 vs. 0.90 ± 0.24, respectively). (2) Contrarily, rats treated with MNU at 3 w developed significantly more tumors than those treated at 7 w (0.56 ± 0.20 vs. 0.11 ± 0.08, respectively). After irradiation at 3 w, MNU treatment at 3 w resulted in an additive effect (0.76 ± 0.20), while treatment at 7 w elicited a synergistic effect (0.71 ± 0.18). <br> [Discussion] Relatively low susceptibility to mammary cancers after prepubertal exposure in rats contradicts with epidemiologic data on A-bomb survivors. However, our data suggest that childhood exposure deposits a long-term effect that becomes apparent in combination with subsequent carcinogen exposure. The nature of this long-term effect remains to be elucidated. |
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| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | 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 | |||||
| 発表年月日 | ||||||
| 日付 | 2005-11-17 | |||||
| 日付タイプ | Issued | |||||
