2022 Fiscal Year Final Research Report
Radiobiological evaluation of linear-no-threshold hypothesis
| Project/Area Number |
18K07725
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 52040:Radiological sciences-related
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| Research Institution | Osaka University (2022)
Nagoya City University (2018-2021) |
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Principal Investigator |
Shibamoto Yuta 大阪大学, 大学院医学系研究科, 招へい教授 (20144719)
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| Co-Investigator(Kenkyū-buntansha) |
杉江 愛生 名古屋市立大学, 医薬学総合研究院(医学), 研究員 (80509258)
岩田 宏満 名古屋市立大学, 医薬学総合研究院(医学), 准教授 (40611588)
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| Project Period (FY) |
2018-04-01 – 2023-03-31
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| Keywords | 低線量放射線 / 直線閾値なし仮説 / 放射線適応応答 |
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| Outline of Final Research Achievements |
To investigate whether the linear-no-threshold hypothesis is acceptable or not, changes in cultured cells, silkworm larvae, and young mice were investigated after continuous low-dose irradiation. In addition, changes in γH2AX index over time were investigated after low- and high-dose irradiation. Continuously-irradiated cultured cells showed radioadaptive responses, and irradiated silkworm larvae showed accelerated growth. In irradiated young mice, transplanted tumor cells developed into solid tumors later as compared to those in non-irradiated mice. The γH2AX index increased soon after both low- and high-dose irradiation, but returned to the pre-irradiation level within 24 hours. The γH2AX indices at 2 hours after irradiation were most closely correlated with cell surviving fractions. These results indicated that low-dose irradiation had no harmful effects on the living organisms, and the linear-no-threshold hypothesis seemed to be invalid.
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| Free Research Field |
放射線腫瘍学・生物学
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| Academic Significance and Societal Importance of the Research Achievements |
直線閾値なし仮説に基づくと、放射線被曝はたとえ微量であっても生体に対して発癌などを含め何らかの悪影響があるとされている。しかし近年はこれとは反対に、微量で適量の放射線は生体に刺激を与えて好影響を及ぼすという研究成果が増えつつある。我々の研究成果は直線閾値なし仮説を否定するものであり、微量の放射線被曝によって生物が様々な点において活性化されうることを示している。これらの研究成果が、国民の放射線に対する認識を変えることに繋がり、放射線アレルギーを無くするために役立つことを期待している。また低線量の放射線被曝が生体の活性化に利用できるようになるきっかけとなることを期待している。
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