Refine your search:     
Report No.
Search Results: Records 1-20 displayed on this page of 37

Presentation/Publication Type

Initialising ...


Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...


Initialising ...


Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Tissue-dependent somaclonal mutation frequencies and spectra enhanced by ion beam irradiation in chrysanthemum

Okamura, Masachika*; Hase, Yoshihiro; Furusawa, Yoshiya*; Tanaka, Atsushi

Euphytica, 202(3), p.333 - 343, 2015/04

 Times Cited Count:13 Percentile:72.08(Agronomy)

We investigated the effect of tissue source selection in combination with ion beam irradiation on generating flower-color mutants in Chrysanthemum morifolium. Petal and leaf tissues of the chrysanthemum cultivar YoMystery (purple flowers) were used. Somaclones regenerated from irradiated tissues were analyzed for stem length and flower color mutation. Three Gy of argon ion beams was regarded as an appropriate dose for irradiation because the resulting color mutants maintained an adequate stem length suitable for commercial use. Statistical analysis of 7,258 individuals from three separate experiments revealed that (1) somaclones from petal tissue had a higher mutation frequency (2.91%) than leaf somaclones (2.01%); (2) the effect of tissue source on the frequency of flower color mutations was significantly enhanced when combined with ion-beam irradiation in that the mutation frequency of ion-beam irradiated petal clones was 6.47%, whereas that of ion-beam irradiated leaf clones was 3.89%; and (3) the spectrum of carotenoid color mutations was remarkably increased by ion-beam irradiation in that both leaf and petal ion-beam irradiated clones had brown, red and yellow flowers in contrast to the somaclones that only produced yellow flowers. These results suggest that intentional or directed induction of flower color mutants with practical value is possible by combining tissue source selection with ion beam irradiation.

Journal Articles

Immunofluorescence observation of oxidative damage of DNA induced by heavy ions from TIARA

Kitabatake, Satomi*; Ushiroda, Tota*; Hirayama, Ryoichi*; Furusawa, Yoshiya*; Funayama, Tomoo; Yokota, Yuichiro; Okahata, Yoshio*; Ito, Atsushi*

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 86, 2015/03

Biological effects of high-LET radiation could be understood in terms of the ion track structure. Therefore the evaluation of the contribution of both core and penumbra regions to biological effects is an important issue for the study of high-LET effects. In the present study, we developed a protocol to make a uniform DNA sheet with insoluble nature in aqueous solution, and explored the applicability to the detection of 8-OHdG distributions after heavy-ion irradiation. Water-insoluble DNA sheet was irradiated with proton and neon ion beams at JAEA-Takasaki. After irradiation DNA samples were incubated with an 8-OHdG antibody followed by with a second antibody containing a fluorescence probe. The preliminary results indicated that upon ion irradiation randomly distributed dot-like fluorescence was observed, suggesting that these dots may be from incident ions.

Journal Articles

Nonhomologous end-joining repair plays a more important role than homologous recombination repair in defining radiosensitivity after exposure to high-LET radiation

Takahashi, Akihisa*; Kubo, Makoto*; Ma, H.*; Nakagawa, Akiko*; Yoshida, Yukari*; Isono, Mayu*; Kanai, Tatsuaki*; Ono, Tatsuya*; Furusawa, Yoshiya*; Funayama, Tomoo; et al.

Radiation Research, 182(3), p.338 - 344, 2014/09

 Times Cited Count:38 Percentile:87.69(Biology)

To clarify whether high-LET radiation inhibits all repair pathways or specifically one repair pathway, studies were designed to examine the effects of radiation with different LET values on DNA DSB repair and radiosensitivity. Embryonic fibroblasts bearing repair gene KO were exposed to X rays, carbon-, iron-, neon- and argon-ion beams. Cell survival was measured with colony-forming assays. The sensitization enhancement ratio (SER) values were calculated using the 10% survival dose of wild-type cells and repair-deficient cells. Cellular radiosensitivity was listed in descending order: double-KO cells $$>$$ NHEJ-KO cells $$>$$ HR-KO cells $$>$$ wild-type cells. Although HR-KO cells had an almost constant SER value, NHEJ-KO cells showed a high-SER value when compared to HR-KO cells, even with increasing LET values. These results suggest that with carbon-ion therapy, targeting NHEJ repair yields higher radiosensitivity than targeting homologous recombination repair.

Journal Articles

Evaluation of SCCVII tumor cell survival in clamped and non-clamped solid tumors exposed to carbon-ion beams in comparison to X-rays

Hirayama, Ryoichi*; Uzawa, Akiko*; Takase, Nobuhiro*; Matsumoto, Yoshitaka*; Noguchi, Miho; Koda, Kana*; Ozaki, Masakuni*; Yamashita, Kei*; Li, H.*; Kase, Yuki*; et al.

Mutation Research; Genetic Toxicology And Environmental Mutagenesis, 756(1-2), p.146 - 151, 2013/08

 Times Cited Count:19 Percentile:60.07(Biotechnology & Applied Microbiology)

Journal Articles

Cell survival fraction estimation based on the probability densities of domain and cell nucleus specific energies using improved microdosimetric kinetic models

Sato, Tatsuhiko; Furusawa, Yoshiya*

Radiation Research, 178(4), p.341 - 356, 2012/10

 Times Cited Count:43 Percentile:86.77(Biology)

Two computational models were established for the estimation on the basis of the concept of the microdosimetric kinetic (MK) model. They were designated as the double-stochastic microdosimetric kinetic (DSMK) and stochastic microdosimetric kinetic (SMK) models, where the former takes the stochastic natures of both domain and cell-nucleus specific energies into account, while the latter considers that of only cell-nucleus specific energy in order to reduce its computational time. Both DSMK and SMK models can reproduce the measured survival fractions even for high-LET and high-dose irradiations for which the conventional MK model predicts lower values due to the ignorance of the stochastic nature of the cell-nucleus specific energies. Those models are therefore capable of contributing to the better understanding of the mechanism of cell inactivation as well as the improvement of the accuracy of the treatment planning of charged-particle therapy.

Journal Articles

Analysis of cell-survival fractions for heavy-ion irradiations based on microdosimetric kinetic model implemented in the particle and heavy ion transport code system

Sato, Tatsuhiko; Watanabe, Ritsuko; Kase, Yuki*; Tsuruoka, Chizuru*; Suzuki, Masao*; Furusawa, Yoshiya*; Niita, Koji*

Radiation Protection Dosimetry, 143(2-4), p.491 - 496, 2011/02

 Times Cited Count:24 Percentile:88.73(Environmental Sciences)

We reanalyzed the survival fraction data, using the microdosimetric-kinetic (MK) model implemented in the PHITS code. It is found from the analysis that the MK model successfully accounts for the cell survival-fractions under a variety of irradiation conditions, using only y* parameter.

Journal Articles

Monte Carlo simulation of radial distribution of DNA strand breaks along the C and Ne ion paths

Watanabe, Ritsuko; Wada, Seiichi*; Funayama, Tomoo; Kobayashi, Yasuhiko; Saito, Kimiaki; Furusawa, Yoshiya*

Radiation Protection Dosimetry, 143(2-4), p.186 - 190, 2011/02

 Times Cited Count:14 Percentile:76.2(Environmental Sciences)

Microscopic energy deposition pattern in an ion track is thought to affect on the spatial distribution of DNA damage as well as the damage spectrum. In this study, we focus on the intra-track spatial distribution of DNA damage in cellular condition based on the energy deposition pattern for each ion obtained by the detailed Monte Carlo track structure simulation. The estimation was performed for C and Ne ions with similar LET around 440 keV/$$mu$$m. As a result, radial DNA damage distribution shows different pattern for C and Ne ions. That is, DSBs or non-DSB type clustered damage are formed in the limited central area while the isolated damages as SSBs and base lesions are spread in larger area. Such tendency is more clearly shown for Ne ions than C ions. This result shows good agreement with the previously obtained experimental observation at TIARA, which indicates the different types of DNA damage shows different distribution pattern around C and Ne projectiles in cell nuclei.

Journal Articles

Induction of DNA DSB and its rejoining in clamped and non-clamped tumours after exposure to carbon ion beams in comparison to X-rays

Hirayama, Ryoichi*; Uzawa, Akiko*; Matsumoto, Yoshitaka*; Noguchi, Miho; Kase, Yuki*; Takase, Nobuhiro*; Ito, Atsushi*; Koike, Sachiko*; Ando, Koichi*; Okayasu, Ryuichi*; et al.

Radiation Protection Dosimetry, 143(2-4), p.508 - 512, 2011/02

 Times Cited Count:10 Percentile:65.84(Environmental Sciences)

We studied double-strand breaks (DSB) induction and rejoining in clamped and non-clamped transplanted tumours in mice leg after exposure to 80 keV/$$mu$$m carbon ions and X-rays. The yields of DSB in the tumours were analysed by a static-field gel electrophoresis. The OER of DSB after X-rays was 1.68, and this value was not changed after 1 h rejoining time (1.40). These damages in oxygenated conditions were rejoined 60-70% within 1 h in situ. No difference was found between the exposure to X-rays and carbon ions for the induction and rejoining of DSB. Thus, the values of OER and rejoined fraction after exposure to carbon ions were similar to those after X-rays, and the calculated relative biological effectivenesses of carbon ion were around 1 under both oxygen conditions. The yields of DSB in vivo depend on exposure doses, oxygen conditions and rejoining time, but not on the types of radiation quality.

Journal Articles

Radioprotection by DMSO in nitrogen-saturated mammalian cells exposed to helium ion beams

Hirayama, Ryoichi*; Matsumoto, Yoshitaka*; Kase, Yuki*; Noguchi, Miho; Ando, Koichi*; Ito, Atsushi*; Okayasu, Ryuichi*; Furusawa, Yoshiya*

Radiation Physics and Chemistry, 78(12), p.1175 - 1178, 2009/12

 Times Cited Count:10 Percentile:60.19(Chemistry, Physical)

The contribution of OH radical-mediated indirect action by particle beams under hypoxic irradiation condition was investigated by using a radical scavenger. V79 cells were irradiated with 150 MeV/nucleon helium ions at an LET of 2.2 keV/mm in the presence or absence of DMSO, and their colony survivals were determined. The contribution of indirect action to cell killing under hypoxic condition was estimated to be 52 %. We conclude that OH radical mediated indirect action still has a half in total contribution on cell killing under hypoxic condition.

Journal Articles

Contributions of direct and indirect actions in cell killing by high-LET radiations

Hirayama, Ryoichi*; Ito, Atsushi*; Tomita, Masanori*; Tsukada, Teruyo*; Yatagai, Fumio*; Noguchi, Miho; Matsumoto, Yoshitaka*; Kase, Yuki*; Ando, Koichi*; Okayasu, Ryuichi*; et al.

Radiation Research, 171(2), p.212 - 218, 2009/02

 Times Cited Count:100 Percentile:95.21(Biology)

The biological effects of radiation originate principally in damages to DNA. DNA damages by X-rays as well as heavy ions are induced by a combination of direct and indirect actions. The contribution of indirect action in cell killing can be estimated from the maximum degree of protection by dimethylsulfoxide (DMSO), which suppresses indirect action without affecting direct action. Exponentially growing Chinese hamster V79 cells were exposed to high-LET radiations of 20 to 2106 keV/$$mu$$m in the presence or absence of DMSO and their survival was determined using a colony formation assay. The contribution of indirect action to cell killing decreased with increasing LET. However, the contribution did not reach zero even at very high LETs and was estimated to be 32% at an LET of 2106 keV/$$mu$$m. Therefore, even though the radiochemically estimated G value of OH radicals was nearly zero at an LET of 1000 keV/$$mu$$m, indirect action by OH radicals contributed to a substantial fraction of the biological effects of high-LET radiations. The RBE determined at a survival level of 10% increased with LET, reaching a maximum value of 2.88 at 200 keV/$$mu$$m, and decreased thereafter. When the RBE was estimated separately for direct action (RBE(D)) and indirect action (RBE(I)); both exhibited an LET dependence similar to that of the RBE, peaking at 200 keV/$$mu$$m. However, the peak value was much higher for RBE(D) (5.99) than RBE(I) (1.89). Thus direct action contributes more to the high RBE of high-LET radiations than indirect action does.

Journal Articles

Heavy-ion microbeam system at JAEA-Takasaki for microbeam biology

Funayama, Tomoo; Wada, Seiichi*; Yokota, Yuichiro; Fukamoto, Kana; Sakashita, Tetsuya; Taguchi, Mitsumasa; Kakizaki, Takehiko*; Hamada, Nobuyuki*; Suzuki, Michiyo; Furusawa, Yoshiya*; et al.

Journal of Radiation Research, 49(1), p.71 - 82, 2008/01

 Times Cited Count:41 Percentile:77.74(Biology)

Research concerning cellular responses to low dose irradiation, radiation-induced bystander effects, and the biological track structure of charged particles has recently received particular attention in the field of radiation biology. Target irradiation employing a microbeam represents a useful means of advancing this research by obviating some of the disadvantages associated with the conventional irradiation strategies. The heavy-ion microbeam system at JAEA-Takasaki can provide target irradiation of heavy charged particles to biological material at atmospheric pressure using a minimum beam size 5 $$mu$$m in diameter. The system can be applied to the investigation of mechanisms within biological organisms not only in the context of radiation biology, but also in the fields of general biology such as physiology, developmental biology and neurobiology, and should help to establish and contribute to the field of "microbeam biology".

Journal Articles

Bystander effect studies using heavy-ion microbeam

Kobayashi, Yasuhiko; Funayama, Tomoo; Sakashita, Tetsuya; Furusawa, Yoshiya*; Wada, Seiichi*; Yokota, Yuichiro; Kakizaki, Takehiko; Hamada, Nobuyuki*; Hara, Takamitsu*; Fukamoto, Kana; et al.

JAEA-Conf 2007-002, p.28 - 35, 2007/02

no abstracts in English

Journal Articles

Particle number- and LET-dependency of bystander effect through the gap junction signalling in human normal fibroblast cells exposed to heavy-ion beams

Matsumoto, Yoshitaka*; Hamada, Nobuyuki*; Aoki, Mizuho*; Wada, Seiichi*; Funayama, Tomoo; Sakashita, Tetsuya; Kakizaki, Takehiko; Kobayashi, Yasuhiko; Furusawa, Yoshiya*

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 110, 2007/02

Journal Articles

Heavy-ion microbeam cell irradiation system at JAERI-Takasaki

Kobayashi, Yasuhiko; Funayama, Tomoo; Wada, Seiichi; Sakashita, Tetsuya; Kakizaki, Takehiko; Hamada, Nobuyuki*; Yokota, Yuichiro; Furusawa, Yoshiya*

KEK Proceedings 2005-5, p.6 - 8, 2005/10

no abstracts in English

Journal Articles

Exploration of "over kill effect" of high-LET Ar- and Fe-ions by evaluating the fraction of non-hit cell and interphase death

Mehnati, P.*; Morimoto, Shigeko*; Yatagai, Fumio*; Furusawa, Yoshiya*; Kobayashi, Yasuhiko; Wada, Seiichi; Kanai, Tatsuaki*; Hanaoka, Fumio*; Sasaki, Hiroshi*

Journal of Radiation Research, 46(3), p.343 - 350, 2005/09

 Times Cited Count:26 Percentile:60.88(Biology)

no abstracts in English

Journal Articles

Microbeams of heavy charged particles

Kobayashi, Yasuhiko; Funayama, Tomoo; Wada, Seiichi; Furusawa, Yoshiya*; Aoki, Mizuho*; Shao, C.*; Yokota, Yuichiro; Sakashita, Tetsuya; Matsumoto, Yoshitaka*; Kakizaki, Takehiko; et al.

Uchu Seibutsu Kagaku, 18(4), p.235 - 240, 2004/12

no abstracts in English

Journal Articles

Bystander effect induced by counted high-LET particles in confluent human fibroblasts; A Mechanistic study

Shao, C.*; Furusawa, Yoshiya*; Kobayashi, Yasuhiko; Funayama, Tomoo; Wada, Seiichi

FASEB Journal, 17(11), p.1422 - 1427, 2003/08

 Times Cited Count:108 Percentile:87.95(Biochemistry & Molecular Biology)

The possible mechanism of a radiation-induced bystander response was investigated by using a high-LET heavy particle microbeam, which allows selected cells to be individually hit with precise numbered particles. Even when only a single cell within the confluent culture was hit by one particle of Ar40 or Ne20, a 1.4-fold increase of micronuclei (MN) was detected demonstrating a bystander response. When 49 cells in the culture were individually hit by 1 to 4 particles, the production of MN in the irradiated cultures were about 2-fold higher than control levels but independent of the number and LET of the particles. MN induction in the irradiated-culture was partly reduced by treatment with DMSO, a scavenger of reactive oxygen species (ROS), and it was almost fully suppressed by the mixture of DMSO and PMA, an inhibitor of gap junctional intercellular communication (GJIC). Accordingly, both ROS and GJIC contribute to the above-mentioned bystander response and GJIC might play an essential role by mediating the release of soluble biochemical factors from targeted cells.

Journal Articles

Lethal effect of K-shell absorption of intracellular phosphorus on wild-type and radiation sensitive mutants of Escherichia coli

Maezawa, Hiroshi*; Furusawa, Yoshiya*; Kobayashi, Katsumi*; Hieda, Kotaro*; Suzuki, Masao*; Usami, Noriko*; Yokoya, Akinari; Mori, Tomoyuki*

Acta Oncologica, 35(7), p.889 - 894, 1997/01

 Times Cited Count:7 Percentile:23.35(Oncology)

no abstracts in English

Oral presentation

Heavy-ion microbeams and bystander effect studies at JAEA-Takasaki

Kobayashi, Yasuhiko; Funayama, Tomoo; Sakashita, Tetsuya; Furusawa, Yoshiya*; Wada, Seiichi*; Yokota, Yuichiro; Kakizaki, Takehiko; Hamada, Nobuyuki*; Ni, M.

no journal, , 

no abstracts in English

Oral presentation

Single-cell irradiation and single-cell assay using heavy-ion microbeams

Kobayashi, Yasuhiko; Funayama, Tomoo; Sakashita, Tetsuya; Furusawa, Yoshiya*; Wada, Seiichi*; Yokota, Yuichiro; Kakizaki, Takehiko; Hamada, Nobuyuki*; Ni, M.

no journal, , 

no abstracts in English

37 (Records 1-20 displayed on this page)