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Journal Articles

Concept of radiation protection for low-dose risks

Takahara, Shogo

Hoshasen Seibutsu Kenkyu, 55(2), p.162 - 172, 2020/06

no abstracts in English

Journal Articles

Report on the Workshop "Radiation Research Based on Computer Simulation" held at the 59th Annual Meeting of the Japanese Radiation Research Society

Sato, Tatsuhiko; Hamada, Nobuyuki*

Hoshasen Seibutsu Kenkyu, 51(4), p.397 - 401, 2016/12

A workshop entitled "Radiation Research Based on Computer Simulation" was held at the 59th annual meeting of the Japanese Radiation Research Society. Approximately 50 participants attended the workshop, and six speakers gave a talk about their computational radiation biology studies. The title of the presentations are "Research on DNA damage and track structure simulation", "Study of cellular response based on stochastic model for simulating irradiated and non-irradiated cells", "Effectiveness of mathematical model for low-dose radiation effect", "Research on particle therapy based on cell surviving fraction model", "Development of model for natural induction of cataract", and "Mathematical model for carcinogenesis considering the differences of temporal and spatial doses". In the workshop, possible future collaborations were intensively discussed. This report briefly summarizes the outline of the workshop.

Journal Articles

Ultraviolet circular dichroism spectroscopy for protein structural study

Izumi, Yudai; Yamamoto, Satoshi*; Fujii, Kentaro; Yokoya, Akinari

Hoshasen Seibutsu Kenkyu, 51(1), p.91 - 106, 2016/03

no abstracts in English

Journal Articles

Single-cell tracking and dynamical analysis of cellular population based on systems biology

Yokoya, Akinari; Kaminaga, Kiichi

Hoshasen Seibutsu Kenkyu, 49(4), p.418 - 431, 2014/12

no abstracts in English

Journal Articles

Novel findings obtained with the colony formation assay of normal human cells

Hamada, Nobuyuki*; Sakashita, Tetsuya; Hara, Takamitsu*; Fujimichi, Yuki*

Hoshasen Seibutsu Kenkyu, 49(3), p.318 - 331, 2014/09

Over the past half century, a colony formation assay has been most commonly used to evaluate cellular radiosensitivity. Our colony formation assay of primary normal human diploid fibroblasts and the analysis of the size and cell numbers in abortive colonies comprising $$<$$ 50 cells and clonogenic colonies comprising $$geq$$ 50 cells led to observations that can potentially answer a fundamental question of what is actually being evaluated in the colony formation assay, and a new phenomenon was also unveiled with the colony formation assay whereby the higher the dose the larger the size of colonies arising from irradiated primary normal human diploid ocular lens epithelial cells. This paper shall review these findings.

Journal Articles

Influence of dose inhomogeneity on cell survival fraction

Sato, Tatsuhiko

Hoshasen Seibutsu Kenkyu, 48(2), p.137 - 146, 2013/06

Radiation doses are inhomogeneously distributed through microscopic sites such as DNA and cell nuclei. Although this inhomogeneity has been regarded as an important factor to determine the relative biological effectiveness (RBE) over 50 years, it had not been frequently used in the quantitative analyses of radiation research because of the difficulty of evaluating the probability density function of dose in microscopic sites. We therefore developed a computational method for calculating the probability density functions in any radiation field and target size by means of combining a multi-scale particle transport simulation code with several mathematical models. Utilizing this method, we established a model for estimating cell-survival fractions in any radiation field. This model employs the probability density functions of domain and cell-nucleus doses as the indexes for characterizing the radiation fields.

Journal Articles

Microscopic energy distribution of low-dose radiation

Watanabe, Ritsuko

Hoshasen Seibutsu Kenkyu, 47(4), p.335 - 346, 2012/12

To comprehend the low-dose radiation induced biological effect from the initial process, the microscopic dose distribution needs to be considered because of its strong ununiformity. In this article, distribution of energy deposition by low-dose $$^{137}$$Cs $$gamma$$-rays calculated using Monte Carlo track structure simulation is presented. Also, the concept of low-dose radiation from a standpoint of microdosimetry is overviewed. This review is a part of special articles on radiation biological effect induced by low-dose and low-dose rate radiation.

Journal Articles

My experience as a consultant for radiation risks; How do we communicate with a client worrying about radiation risks?

Akamatsu, Ken

Hoshasen Seibutsu Kenkyu, 46(2), p.87 - 92, 2011/06

"Health counseling hot line" concerning the radiation and the radiological consequence was established in the Ministry of Education, Culture, Sports, Science and Technology along with the nuclear disaster due to the East Japan great earthquake. The author and some other staffs of Japan Atomic Energy Agency were consulted by a lot of Japanese clients as a temporary risk-communicator. The concern for nuclear power and the radioactivity and the radiation has spread not only domestically but also all over the world by this disastrous. In this paper, the author discusses how we communicate with a client worrying about radiation risks based on his experiences.

Journal Articles

Effects of ionizing radiation on the behavior and learning of ${it C. elegans}$

Sakashita, Tetsuya; Suzuki, Michiyo

Hoshasen Seibutsu Kenkyu, 46(1), p.30 - 46, 2011/04

The study of the effects of ionizing radiation on the nervous system is important and potential risk on the nuclear plant accidents and space missions. We have studied the effects of learning behavior of ${it C. elegans}$. Here, we report the recent findings on this project, and also review the effects of ionizing radiation on the other organisms. Our findings may provide an important key to understand the human risk.

Journal Articles

Initiation of systems radiation biology in Japan

Sakashita, Tetsuya; Suzuki, Michiyo; Ouchi, Noriyuki; Ban, Nobuhiko*

Hoshasen Seibutsu Kenkyu, 45(4), p.379 - 395, 2010/12

Recently, systems radiation biology (SRB) has been studied and developed in Europe and USA. Also, Japanese researchers in radiation biology are interested in this research field, gradually. In this review, four scientists shortly review SRB in each stand points.

Journal Articles

Integration of macrodosimetry with microdosimetry; Biological dose estimation method adopting lineal energy y instead of LET as the index for expressing RBE

Sato, Tatsuhiko

Hoshasen Seibutsu Kenkyu, 45(2), p.149 - 159, 2010/06

Integration of macro-dosimetry with micro-dosimetry is of great importance for the improvement of various dosimetric researches such as biological dose estimation for charged-particle therapy. This article explains the difference of the concepts between micro-dosimetry and macro-dosimetry, and reviews our recent works related to the establishment of the model for calculating the microscopic lineal-energy distributions in macroscopic matters. Our developed biological-dose-estimation method based on lineal energy instead of LET is also described in this report.

Journal Articles

My impressions on "Heavy Ions in Therapy and Space Symposium 2009"

Sato, Tatsuhiko

Hoshasen Seibutsu Kenkyu, 44(3), p.365 - 369, 2009/09

My impressions on "Heavy Ions in Therapy and Space Symposium 2009" is given in this report.

Journal Articles

Applications of heavy-ion microbeams in biological studies

Kobayashi, Yasuhiko; Funayama, Tomoo; Hamada, Nobuyuki*; Sakashita, Tetsuya; Yokota, Yuichiro; Fukamoto, Kana; Suzuki, Michiyo; Taguchi, Mitsumasa

Hoshasen Seibutsu Kenkyu, 43(2), p.150 - 169, 2008/06

no abstracts in English

Journal Articles

A Review on radiation tolerance mechanism of higher plants

Yokota, Yuichiro; Inoue, Masayoshi; Narumi, Issei; Funayama, Tomoo; Kobayashi, Yasuhiko; Tanaka, Atsushi

Hoshasen Seibutsu Kenkyu, 42(4), p.402 - 415, 2007/12

It has been known that many types of higher plants are several hundred times more radio-tolerant than mammals at an individual level. There was, however, no available information on the detail mechanism of radiation tolerance of higher plants. Thus, we have done the radiobiological studies using tobacco BY-2 cell line as a model plant cell. In their studies, we made clear that tobacco cells are ten times more radio-tolerant than mammalian cells, and that radioresistant tobacco cells can tolerate a large number of DNA double-strand breaks compared with mammalian cells. In this review, we discussed the radiation tolerant mechanism of higher plants by taking together the past findings with our latest data: tobacco cells are tolerant of radiation-induced chromosomal aberration although DNA double-strand break repair abilities of tobacco and mammalian cells are almost the same.

Journal Articles

Biological effects of clustered DNA damage

Shikazono, Naoya; Urushibara, Ayumi; Fujii, Kentaro; Yokoya, Akinari

Hoshasen Seibutsu Kenkyu, 41(4), p.409 - 423, 2006/12

no abstracts in English

Journal Articles

Clustered DNA damage induced by ionizing radiaton

Yokoya, Akinari; Shikazono, Naoya; Urushibara, Ayumi; Fujii, Kentaro; Akamatsu, Ken; Watanabe, Ritsuko

Hoshasen Seibutsu Kenkyu, 40(2), p.168 - 184, 2005/06

Ionizing radiation causes modifications in a DNA molecule depending on the characteristic tack-structure in which two or more isolated lesions arise in a few nm scale (1 or 2 helical turn of DNA), known as "clustered DNA damage". These clustered DNA damages could be distinct from those by reactive oxygen species (ROS) endogenously induced on their severity of induction of biological effects such as mutation. However, the studies on the nature and repair mechanism of clustered DNA damage have still been behind because of the technical difficulties on determination of the chemical structure and yield. This article reviews some experimental evidences of the clustered DNA damages in this research field, as well as our recent progress on the studies on the clustered DNA damages using both molecular biological techniques and synchrotron spectroscopic method.

Journal Articles

The Microbeam system in JAERI-Takasaki for biological applications

Funayama, Tomoo; Kobayashi, Yasuhiko

Hoshasen Seibutsu Kenkyu, 37(3), p.334 - 347, 2002/09

In JAERI-Takasaki, the heavy ion microbeam system was developed, and utilized to irradiate biological materials. However, the utilization of microbeam system was mainly in the radio-surgery tool for analyzing insect development and plant root differentiation. This was because some beam technological and biological difficulties existed in irradiating cultured cell with high LET ion beam. Recently, we established a efficient and practical way for irradiating mammalian cultured cell with our microbeam apparatus. In this paper, the outlines of our micro beam system and the actual process for cultured cell irradiation will be described.

Journal Articles

Microbeam studies to investigate the function of living cells and response to radiation

Kobayashi, Yasuhiko

Hoshasen Seibutsu Kenkyu, 37(1), p.67 - 84, 2002/03

A single cell irradiation system has been developed for targeting cells individually with a precise number of high-LET heavy ions to elucidate radiobiological effects of exactly one particle and to investigate the interaction of damages produced by separate events. Using the heavy ion microbeam apparatus in TIARA, mammalian cells were irradiated in the atmosphere with a single or precise numbers of heavy ions, 13.0 MeV/u 20Ne or 11.5 MeV/u 40Ar, with a spatial resolution of a few microns.

Journal Articles

The Mechanism of radiation hyper-resistance of Deinococcus radiodurans

Narumi, Issei; Kikuchi, Masahiro; Funayama, Tomoo; Sato, Katsuya

Hoshasen Seibutsu Kenkyu, 34(4), p.401 - 418, 1999/00

no abstracts in English

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