1
|
Kinugawa T, Tanaka IB, Tanaka S, Manabe Y, Sato F, Wada T. An analysis of the effects of chronic low dose-rate radiation exposure on cancer focusing on the differences among cancer types. Int J Radiat Biol 2024:1-9. [PMID: 38652836 DOI: 10.1080/09553002.2024.2338551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/26/2024] [Indexed: 04/25/2024]
Abstract
PURPOSE The effect of chronic low dose-rate radiation exposure on cancers was investigated by analyzing the data of mice experiments conducted at the Institute for Environmental Sciences (IES). This analysis focuses on the differences between malignant lymphomas and solid cancers. MATERIALS AND METHODS The analysis is conducted based on the mathematical model introduced in our previous work. The model is expanded to analyze malignant lymphomas and solid cancers separately. Using the expanded model, the effect of chronic low dose-rate radiation on malignant lymphomas and solid cancers are discussed based on their occurrences, progressions, and mortalities. RESULTS Non-irradiated control group and 20 mGy/day × 400 days irradiated groups are analyzed. The analysis showed that radiation exposure shortened mean life expectancy for both malignant lymphomas and solid cancers (shorter by 89.6 days for malignant lymphomas and 149.3 days for solid cancers). For malignant lymphomas, both the occurrence and the progression are affected by radiation exposure. The mean age at which malignant lymphoma developed in mice was shortened by 32.7 days and the mean progression period was shortened by 57.3 days. The occurrence of solid cancer is also affected by radiation exposure, wherein the mean age at which solid cancer develops was shortened by 147.9 days. However, no significant change in progression period of solid cancers was seen in the analysis. CONCLUSIONS The analysis showed that the occurrence and mean lifespan are affected in both malignant lymphomas and solid cancers. The shortening of the progression period is only seen in malignant lymphoma, no significant change was observed in solid cancers.
Collapse
Affiliation(s)
- Tetsuhiro Kinugawa
- Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Ignacia Braga Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, Rokkasho-mura, Japan
| | - Satoshi Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, Rokkasho-mura, Japan
| | - Yuichiro Manabe
- Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Fuminobu Sato
- Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Takahiro Wada
- Department of Pure and Applied Physics, Kansai University, Suita, Japan
| |
Collapse
|
2
|
Kinugawa T, Tanaka IB, Tanaka S, Manabe Y, Sato F, Wada T. A mathematical model for radiation-induced life-shortening attributed to cancer. Int J Radiat Biol 2024; 100:176-182. [PMID: 37755376 DOI: 10.1080/09553002.2023.2261529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 09/07/2023] [Indexed: 09/28/2023]
Abstract
PURPOSE In this paper, we described our mathematical model for radiation-induced life shortening in detail and applied the model to the experimental data on mice to investigate the effect of radiation on cancer-related life-shortening. MATERIALS AND METHODS Our mathematical model incorporates the following components: (i) occurrence of cancer, (ii) progression of cancer over time, and (iii) death from cancer. We evaluated the progression of cancer over time by analyzing the cancer incidence data and cumulative mortalities data obtained from mice experiments conducted at the Institute for Environmental Sciences (IES). RESULTS We analyzed non-irradiated control and 20 mGy/day × 400 days irradiated groups. In the analysis, all malignant neoplasms were lumped together and referred to as 'cancer'. Our analysis showed that the reduction in lifespan (104 days in median) was the result of the early onset of cancer (68 days in median) and the shortening of the cancer progression period (48 days in median). CONCLUSIONS We described in detail our mathematical model for radiation-induced life-shortening attributed to cancer. We analyzed the mice data obtained from the experiment conducted at the IES using our model. We decomposed radiation-induced life-shortening into the early onset of cancer and the shortening of the cancer progression period.
Collapse
Affiliation(s)
- Tetsuhiro Kinugawa
- Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Ignacia Braga Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, Rokkasho-mura, Japan
| | - Satoshi Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, Rokkasho-mura, Japan
| | - Yuichiro Manabe
- Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Fuminobu Sato
- Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Takahiro Wada
- Department of Pure and Applied Physics, Kansai University, Suita, Japan
| |
Collapse
|
3
|
Takahashi J, Tanaka IB. The mitigating effect of feeding lucerne hay cubes supplemented with an optimal combination of nitrate with l-cysteine on enteric methane emission in sheep. Sci Total Environ 2024; 906:167747. [PMID: 37848148 DOI: 10.1016/j.scitotenv.2023.167747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 10/09/2023] [Accepted: 10/09/2023] [Indexed: 10/19/2023]
Abstract
The combination of optimal nitrate and l-cysteine to safely mitigate rumen methane (CH4) emissions in ruminants was studied in an open-circuit respiration head-hood system using four rumen-fistulated Suffolk wethers in a 4 × 4 Latin square design. Four treatments were set up Control: fed on lucerne hay cubes without nitrate and l-cysteine, Nitrate: fed on lucerne hay cubes with 0.18 % NO3--N in dry matter (DM)), N + Cys-H: fed on lucerne hay cubes supplemented with 0.18 % NO3--N and 0.74 % l-cysteine (equivalent to half the upper limit of effective S requirement in DM), and N + Cys-Q: fed on lucerne hay cubes supplemented with 0.18 % NO3--N and 0.37 % l-cysteine (equivalent to 1/4 of the upper limit of effective S requirement in DM). In this experiment, the ingested nitrate at a subclinical concentration/s (0.18 % in DM) increased by 11.2 % mean methemoglobin value and alleviated rumen methanogenesis by 47 %. Administration of l-cysteine set at 0.74 % and 0.37 % in DM reduced by 68 % and 58 % methemoglobin formed by nitrate alone, respectively (P < 0.05). However, daily mitigation of CH4 emissions decreased by 35 % with the addition of l-cysteine at both addition concentration/s compared with Control. The results of this study suggest that mitigation of enteric methane emissions by the combination of nitrate and l-cysteine can be achieved by feeding diets in which the nitrate content is maintained at around 0.18 % NO3--N in DM and l-cysteine addition is adjusted to 0.37-0.74 % in DM. This method would be recommended as a safe, efficient, and practical way to mitigate enteric CH4 emissions leading to increased productivity while reducing the increased N excretion that causes N2O emissions.
Collapse
Affiliation(s)
- Junichi Takahashi
- Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan.
| | - Ignacia Braga Tanaka
- Advanced Molecular Bio-Sciences Research Center, Institute for Environmental Sciences, Rokkasho 039-3212, Japan.
| |
Collapse
|
4
|
Kohda A, Toyokawa T, Umino T, Ayabe Y, Tanaka IB, Komura JI. Frequencies of Chromosome Aberrations are Lower in Splenic Lymphocytes from Mice Continuously Exposed to Very Low-Dose-Rate Gamma Rays Compared with Non-Irradiated Control Mice. Radiat Res 2022; 198:639-645. [PMID: 36481804 DOI: 10.1667/rade-21-00159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/06/2022] [Indexed: 12/02/2022]
Abstract
Chromosome aberrations have been one of the most sensitive and reliable biomarkers of exposure to ionizing radiation. Using the multiplex fluorescence in situ hybridization (M-FISH) technique, we compared the changes, over time, in the frequencies of translocations and of dicentric chromosomes in the splenic lymphocytes from specific pathogen-free (SPF) C3H/HeN female mice continuously exposed to 0.05 mGy/day (18.25 mGy/year) gamma rays for 125 to 700 days (total accumulated doses: 6.25-35 mGy) with age-matched non-irradiated controls. Results show that the frequencies of translocations and of dicentric chromosomes increased significantly over time in both irradiated and non-irradiated control mice, and that the frequencies were significantly lower, not higher, in the irradiated mice, which differs from our previous reports of increased chromosome aberration frequencies at higher radiation dose rates of 1 mGy/day and 20 mGy/day. These results will be useful when considering the radiation risk at very low-dose rates comparable to regulatory dose limits.
Collapse
Affiliation(s)
- Atsushi Kohda
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121 Hacchazawa, Takahoko, Rokkasho, Kamikita, Aomori 039-3213, Japan
| | - Takuo Toyokawa
- Tohoku Nuclear Co., Ltd., 2-41-14 Higashi Okamisawa, Misawa, Aomori 033-0024, Japan
| | - Tomoyuki Umino
- Tohoku Nuclear Co., Ltd., 2-41-14 Higashi Okamisawa, Misawa, Aomori 033-0024, Japan
| | - Yoshiko Ayabe
- Tohoku Research Center, Forestry and Forest Product Research Institute, 92-25 Nabeyashiki, Shimo-Kuriyagawa, Morioka, Iwate 020-0123, Japan
| | - Ignacia Braga Tanaka
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121 Hacchazawa, Takahoko, Rokkasho, Kamikita, Aomori 039-3213, Japan
| | - Jun-Ichiro Komura
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121 Hacchazawa, Takahoko, Rokkasho, Kamikita, Aomori 039-3213, Japan
| |
Collapse
|
5
|
Kohda A, Toyokawa T, Umino T, Ayabe Y, Tanaka IB, Komura JI. Frequencies of Chromosome Aberrations are Lower in Splenic Lymphocytes from Mice Continuously Exposed to Very Low-Dose-Rate Gamma Rays Compared with Non-Irradiated Control Mice. Radiat Res 2022:487823. [PMID: 36270025 DOI: 10.1667/rade-21-00159.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/06/2022] [Indexed: 11/03/2022]
Abstract
Chromosome aberrations have been one of the most sensitive and reliable biomarkers of exposure to ionizing radiation. Using the multiplex fluorescence in situ hybridization (M-FISH) technique, we compared the changes, over time, in the frequencies of translocations and of dicentric chromosomes in the splenic lymphocytes from specific pathogen-free (SPF) C3H/HeN female mice continuously exposed to 0.05 mGy/day (18.25 mGy/year) gamma rays for 125 to 700 days (total accumulated doses: 6.25-35 mGy) compare with age-matched non-irradiated controls. Results show that the frequencies of translocations and of dicentric chromosomes increased significantly over time in both irradiated and non-irradiated control mice, and that the frequencies were significantly lower, not higher, in the irradiated mice, which differs from our previous reports of increased chromosome aberration frequencies at higher radiation dose rates of 1 mGy/day and 20 mGy/day. These results will be useful when considering the radiation risk at very low-dose rates comparable to regulatory dose limits.
Collapse
Affiliation(s)
- Atsushi Kohda
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121 Hacchazawa, Takahoko, Rokkasho, Kamikita, Aomori 039-3213, Japan
| | - Takuo Toyokawa
- Tohoku Nuclear Co., Ltd., 2-41-14 Higashi Okamisawa, Misawa, Aomori 033-0024, Japan
| | - Tomoyuki Umino
- Tohoku Nuclear Co., Ltd., 2-41-14 Higashi Okamisawa, Misawa, Aomori 033-0024, Japan
| | - Yoshiko Ayabe
- Tohoku Research Center, Forestry and Forest Product Research Institute, 92-25 Nabeyashiki, Shimo-Kuriyagawa, Morioka, Iwate 020-0123, Japan
| | - Ignacia Braga Tanaka
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121 Hacchazawa, Takahoko, Rokkasho, Kamikita, Aomori 039-3213, Japan
| | - Jun-Ichiro Komura
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121 Hacchazawa, Takahoko, Rokkasho, Kamikita, Aomori 039-3213, Japan
| |
Collapse
|
6
|
Sugihara T, Murano H, Fujikawa K, Tanaka IB, Komura JI. ADAPTIVE RESPONSE IN MICE CONTINUOUSLY IRRADIATED WITH LOW DOSE-RATE RADIATION. Radiat Prot Dosimetry 2022; 198:1196-1199. [PMID: 36083770 DOI: 10.1093/rpd/ncac151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
Previous reports showed a reduction in hematopoietic death in mice exposed to a high (challenge) radiation dose if exposed two weeks prior with a relatively small (priming) radiation dose (0.3-0.5 Gy). This in vivo acquisition of radioresistance, known as "adaptive response" or the "Yonezawa effect," was shown in the experiments performed using high dose-rates (HDR) for priming. In the present study, we used low (LDR) and medium dose-rates (MDR) of radiation for priming in male C57BL mice. A total dose of 0.45-0.46 Gy (LDR, 20 mGy/day × 23 days or MDR, 18 mGy/hour × 25 hours) was used for priming, and was followed by challenge exposure 12 days later at an HDR (0.8 Gy/min) to a total dose of 6.75 Gy. Increased survival rates were observed in mice exposed to priming radiation delivered at LDR or MDR, suggesting that the adaptive responses induced are comparable with those induced at HDR.
Collapse
Affiliation(s)
- Takashi Sugihara
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121, Hacchazawa, Takahoko, Rokkasho, Aomori 039-3213, Japan
| | - Hayato Murano
- TESSCO, 330-2, Notsuke, Obuchi, Rokkasho, Aomori 039-3212, Japan
| | | | - Ignacia Braga Tanaka
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121, Hacchazawa, Takahoko, Rokkasho, Aomori 039-3213, Japan
| | - Jun-Ichiro Komura
- Department of Radiobiology, Institute for Environmental Sciences (IES), 2-121, Hacchazawa, Takahoko, Rokkasho, Aomori 039-3213, Japan
| |
Collapse
|
7
|
Tanaka IB. EXPERIMENTAL STUDIES AT THE IES ON THE BIOLOGICAL EFFECTS OF CHRONIC LOW DOSE-RATE RADIATION EXPOSURE IN MICE. Radiat Prot Dosimetry 2022; 198:985-989. [PMID: 36083746 DOI: 10.1093/rpd/ncac025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 02/06/2022] [Accepted: 02/08/2022] [Indexed: 06/15/2023]
Abstract
Research in the Department of Radiobiology at the Institute for Environmental Sciences (IES) has focused mainly on the biological effects of long-term low dose-rate radiation exposure on mice since its establishment 30 y ago. The IES has exposed thousands of mice of various strains, to gamma-rays, mostly chronically, at low dose-rates of 0.05, 1, 20 or 100 mGy/d, at medium dose-rates of 200 or 400 mGy/d or at acute high dose-rates of 0.7-0.9 Gy/min. The dose-rate 0.05 mGy/d is comparable with the dose limit for radiation workers of 100 mSv/5 y. The results will be presented based on the parameters examined at various endpoints such as life span, neoplasm (cancer incidence), chromosome aberrations frequencies, alterations in mRNA levels, tumour transplantability and developmental abnormalities after in utero exposures. The results from research collaborations with universities and institutions both domestic (within Japan) and international will be presented. Lastly, an outline of experiments (e.g. juvenile exposure, low dose tritium exposures) and projects (e.g. radiobiology archives) currently in progress and future research perspectives will be described.
Collapse
Affiliation(s)
- Ignacia Braga Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, 1-7, Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan
| |
Collapse
|
8
|
Jaylet T, Quintens R, Benotmane MA, Luukkonen J, Tanaka IB, Ibanez C, Durand C, Sachana M, Azimzadeh O, Adam-Guillermin C, Tollefsen KE, Laurent O, Audouze K, Armant O. Development of an Adverse Outcome Pathway for radiation-induced microcephaly via expert consultation and machine learning. Int J Radiat Biol 2022; 98:1752-1762. [PMID: 35947014 DOI: 10.1080/09553002.2022.2110312] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Brain development during embryogenesis and in early postnatal life is particularly complex and involves the interplay of many cellular processes and molecular mechanisms, making it extremely vulnerable to exogenous insults, including ionizing radiation (IR). Microcephaly is one of the most frequent neurodevelopmental abnormalities that is characterized by small brain size, and is often associated with intellectual deficiency. Decades of research span from epidemiological data on in utero exposure of the A-bomb survivors, to studies on animal and cellular models that allowed deciphering the most prominent molecular mechanisms leading to microcephaly. The Adverse Outcome Pathway (AOP) framework is used to organize, evaluate and portray the scientific knowledge of toxicological effects spanning different biological levels of organizations, from the initial interaction with molecular targets to the occurrence of a disease or adversity. In the present study, the framework was used in an attempt to organize the current scientific knowledge on microcephaly progression in the context of ionizing radiation (IR) exposure. This work was performed by a group of experts formed during a recent workshop organized jointly by the Multidisciplinary European Low Dose Initiative (MELODI) and the European Radioecology Alliance (ALLIANCE) associations to present the AOP approach and tools. Here we report on the development of a putative AOP for congenital microcephaly resulting from IR exposure based on discussions of the working group and we emphasize the use of a novel machine-learning approach to assist in the screening of the available literature to develop AOPs. CONCLUSION The expert consultation led to the identification of crucial biological events for the progression of microcephaly upon exposure to IR, and highlighted current knowledge gaps. The machine learning approach was successfully used to screen the existing knowledge and helped to rapidly screen the body of evidence and in particular the epidemiological data. This systematic review approach also ensured that the analysis was sufficiently comprehensive to identify the most relevant data and facilitate rapid and consistent AOP development. We anticipate that as machine learning approaches become more user-friendly through easy-to-use web interface, this would allow AOP development to become more efficient and less time consuming.
Collapse
Affiliation(s)
- Thomas Jaylet
- Université Paris Cité, T3S, Inserm UMRS 1124, Paris, France
| | - Roel Quintens
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK-CEN, Mol, Belgium
| | | | - Jukka Luukkonen
- University of Eastern Finland, Kuopio Campus, Department of Environmental and Biological Sciences, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Ignacia Braga Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, 1-7 lenomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan
| | - Chrystelle Ibanez
- PSE-SANTE/SESANE/LRTOX Institut de Radioprotection et de Sûreté Nucléaire (IRSN), F-92262, Fontenay-aux-Roses, France
| | - Christelle Durand
- PSE-SANTE/SESANE/LRTOX Institut de Radioprotection et de Sûreté Nucléaire (IRSN), F-92262, Fontenay-aux-Roses, France
| | - Magdalini Sachana
- Organisation for Economic Co-operation and Development (OECD), Environment Health and Safety Division, 75775 CEDEX 16 Paris, France
| | - Omid Azimzadeh
- Federal Office for Radiation Protection (Bfs), Section Radiation Biology, 85764 Neuherberg, Germany
| | - Christelle Adam-Guillermin
- PSE-SANTE/SDOS/LMDN, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Cadarache, 13115 Saint-Paul-Lez-Durance, France
| | - Knut Erik Tollefsen
- Norwegian Institute for Water Research (NIVA), Økernveien 94, N-0579, Oslo, Norway.,Norwegian University of Life Sciences (NMBU), Post box 5003, N-1432 Ås, Norway.,Centre for Environmental Radioactivity, Norwegian University of Life Sciences (NMBU), Post box 5003, N-1432 Ås, Norway
| | - Olivier Laurent
- PSE-SANTE/SESANE/LEPID, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), F-92262, Fontenay-aux-Roses, France
| | - Karine Audouze
- Université Paris Cité, T3S, Inserm UMRS 1124, Paris, France
| | - Olivier Armant
- PSE-ENV/SRTE/LECO, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Cadarache, 13115 Saint-Paul-Lez-Durance, France
| |
Collapse
|
9
|
Takahashi N, Misumi M, Niwa Y, Murakami H, Ohishi W, Inaba T, Nagamachi A, Tanaka S, Braga Tanaka I, Suzuki G. Effects of Radiation on Blood Pressure and Body Weight in the Spontaneously Hypertensive Rat Model. Are Radiation Effects on Blood Pressure Affected by Genetic Background? Radiat Res 2020; 193:552-559. [PMID: 32150496 DOI: 10.1667/rr15536.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 01/28/2020] [Indexed: 11/03/2022]
Abstract
In this work, we utilized spontaneously hypertensive rats (SHR) and Wister Kyoto rats (WKY), from which the SHR was established, to evaluate the effects of whole-body acute radiation on the cardiovascular system at doses from 0 to 4 Gy. In the irradiated SHR, the systolic blood pressure (SBP) increased with increasing dose, while body weight gain decreased with increasing radiation dose. Furthermore, pathological observations of SHR demonstrated that the number of rats with cystic degeneration in the liver increased with increasing dose. The effects observed among SHR, such as increased SBP and retardation of body weight gain, appear very similar to those observed in Japanese atomic bomb survivors. In contrast, the SBP among WKY did not change relative to dose; the body weight, however, did change, as in the SHR. Therefore, the association between radiation exposure and SBP, but not between radiation exposure and retardation of body weight gain, may be affected by genetic background, as evident from strain difference. These results suggest that the SHR and WKY animal models may be useful for studying radiation effects on non-cancer diseases including circulatory diseases, chronic liver disease and developmental retardation.
Collapse
Affiliation(s)
- Norio Takahashi
- Consultant, Radiation Effects Research Foundation (RERF), Hiroshima, 732-0815, Japan
| | - Munechika Misumi
- Department of Statistics, Radiation Effects Research Foundation (RERF), Hiroshima, 732-0815, Japan
| | - Yasuharu Niwa
- Department of Molecular Biosciences, Radiation Effects Research Foundation (RERF), Hiroshima, 732-0815, Japan
| | - Hideko Murakami
- Department of Molecular Biosciences, Radiation Effects Research Foundation (RERF), Hiroshima, 732-0815, Japan
| | - Waka Ohishi
- Department of Clinical Studies (Hiroshima), Radiation Effects Research Foundation (RERF), Hiroshima, 732-0815, Japan
| | - Toshiya Inaba
- Department of Molecular Oncology and Leukemia Program Project, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8553, Japan
| | - Akiko Nagamachi
- Department of Molecular Oncology and Leukemia Program Project, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8553, Japan
| | - Satoshi Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, Aomori, 039-3212, Japan
| | - Ignacia Braga Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, Aomori, 039-3212, Japan
| | - Gen Suzuki
- International University of Health and Welfare Clinic, Tochigi, 324-8501, Japan
| |
Collapse
|
10
|
Gulay KCM, Tanaka IB, Komura J, Tanaka S. Effects of Continuous Gamma-Ray Exposure In Utero in B6C3F1 Mice on Gestation Day 18 and at 10 Weeks of Age. Radiat Res 2018; 189:425-440. [PMID: 29437533 DOI: 10.1667/rr14863.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Pregnant C57BL/6JJcl mice were exposed to γ rays at low dose rate (20 mGy/day, LDR) or medium dose rate (200 and 400 mGy/day, MDR) from gestation day (GD) 0-18 to total accumulated doses of 360, 3,600 and 7,200 mGy, respectively. An additional group of pregnant mice were acutely exposed to 2 Gy at high dose rate (HDR) of 0.77 Gy/min on GD 11. In experiment 1, fetuses collected via cesarean section on GD 18 were examined for external and skeletal abnormalities. While the results of LDR exposure (20 mGy/day) did not significantly differ from the nonirradiated controls in all parameters examined, MDR (200 and 400 mGy/day) and acute HDR (2 Gy) exposure caused growth retardation and significantly increased incidence of unossified bones. Increased incidence of external abnormalities was observed only in the acute HDR group. In experiment 2, the dams were allowed to give birth and the pups were clinically monitored and weighed periodically until 10 weeks of age when they were sacrificed and subjected to pathological examination. Pups exposed at MDRs of 200 and 400 mGy/dayand at acute HDR of 0.77 Gy/min had lower bodyweights from weaning (3 weeks) to 10 weeks of age except for females exposed to 400 mGy/day MDR. None of the pups exposed to an acute 2 Gy dose on GD 11 survived to 10 weeks of age. Histopathological changes were not significantly different between the nonirradiated control and the 20 mGy/day LDR groups. However, at both MDR exposures of 200 and 400 mGy/day. gonadal (testes and ovary) hypoplasia/atrophy was observed in all the 10-week-old pups. Our results show that in utero LDR exposure to 20 mGy/day for the entire gestation period did not cause any significant effect in pups when compared to the nonirradiated controls up to 10 weeks of age. However, pups exposed in utero to MDRs showed dose-related growth retardation with delayed ossifications (400 mGy/day) and gonadal hypoplasia/atrophy. These findings suggest that increased post-implantation loss in dams exposed at MDR is due to early embryonic deaths resulting in early resorption.
Collapse
Affiliation(s)
- K C M Gulay
- Department of Radiobiology, Institute for Environmental Sciences, 1-7, Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan
| | - I B Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, 1-7, Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan
| | - J Komura
- Department of Radiobiology, Institute for Environmental Sciences, 1-7, Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan
| | - S Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, 1-7, Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan
| |
Collapse
|
11
|
Tanaka IB, Tanaka S, Ichinohe K, Matsushita S, Matsumoto T, Otsu H, Oghiso Y, Sato F. Cause of Death and Neoplasia in Mice Continuously Exposed to Very Low Dose Rates of Gamma Rays. Radiat Res 2007; 167:417-37. [PMID: 17388697 DOI: 10.1667/rr0728.1] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 11/15/2006] [Indexed: 11/03/2022]
Abstract
Four thousand 8-week-old SPF B6C3F1 mice (2000 of each sex) were divided into four groups, one nonirradiated (control) and three irradiated. The irradiated groups were exposed to (137)Cs gamma rays at dose rates of 21, 1.1 and 0.05 mGy day(-1) for approximately 400 days with total doses equivalent to 8000, 400 and 20 mGy, respectively. All mice were kept until natural death, and pathological examination was performed to determine the cause of death. Neoplasms accounted for >86.7% of all deaths. Compared to the nonirradiated controls, the frequency of myeloid leukemia in males, soft tissue neoplasms and malignant granulosa cell tumors in females, and hemangiosarcoma in both sexes exposed to 21 mGy day(-1) were significantly increased. The number of multiple primary neoplasms per mouse was significantly increased in mice irradiated at 21 mGy day(-1). Significant increases in body weights were observed from 32 to 60 weeks of age in males and females exposed to 1.1 mGy day(-1) and 21 mGy day(-1), respectively. Our results suggest that life shortening (Tanaka et al., Radiat. Res. 160, 376-379, 2003) in mice continuously exposed to low-dose-rate gamma rays is due to early death from a variety of neoplasms and not from increased incidence of specific neoplasms.
Collapse
Affiliation(s)
- I B Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, Aomori, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Tanaka S, Tanaka IB, Sasagawa S, Ichinohe K, Takabatake T, Matsushita S, Matsumoto T, Otsu H, Sato F. No lengthening of life span in mice continuously exposed to gamma rays at very low dose rates. Radiat Res 2003; 160:376-9. [PMID: 12926996 DOI: 10.1667/rr3042] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Late effects of continuous exposure to ionizing radiation are potential hazards to workers in radiation facilities as well as to the general public. Recently, low-dose-rate and low-dose effects have become a serious concern. Using a total of 4000 mice, we studied the late biological effects of chronic exposure to low-dose-rate radiation as assayed by life span. Two thousand male and 2000 female 8-week-old specific-pathogen-free (SPF) B6C3F1 mice were randomly divided into four groups (one nonirradiated control and three irradiated). Irradiation was carried out for approximately 400 days using (137)Cs gamma rays at dose rates of 21 mGy day(-1), 1.1 mGy day(-1) and 0.05 mGy day(-1) with total doses equivalent to 8000 mGy, 400 mGy and 20 mGy, respectively. All mice were kept under SPF conditions until they died spontaneously. Statistical analyses showed that the life spans of mice of both sexes irradiated with 21 mGy day(-1) (P < 0.0001) and of females irradiated with 1.1 mGy day(-1) (P < 0.05) were significantly shorter than those of the control group. Our results show no evidence of lengthened life span in mice continuously exposed to very low dose rates of gamma rays.
Collapse
Affiliation(s)
- S Tanaka
- Department of Radiobiology, Institute for Environmental Sciences, 1-7, Ienomae, Obuchi, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|