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Tsubone, Misora*; Shimotsuma, Yasuhiko*; Kono, Yoshio*; Kakizawa, Sho*; Yamada, Hiroki*; Kobayashi, Keita; Shimizu, Masahiro*; Miura, Kiyotaka*
NPG Asia Materials, 18, p.15_1 - 15_16, 2026/04
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Silica glass exhibits diverse structural configurations accompanied with densification under varying temperature and pressure conditions; these factors significantly influence its optical properties, such as the refractive index. However, the fundamental structural mechanisms underlying the optical properties change induced by high pressure treatment and femtosecond laser direct writing remain poorly understood. Herein, we report the similarities and differences in the optical responses of densified silica glass induced by these two methods. The most significant difference is that the laser-irradiated region evolves toward a glass structure characteristic of a high fictive temperature by incorporating non-bridging oxygen defects associated with edge-sharing SiO
tetrahedra, which induces distinctly different photoluminescence behaviors compared to high pressure treatment.
Yokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Sakashita, Tetsuya; Suzuki, Michiyo; Kobayashi, Yasuhiko
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 67, 2016/02
The role of nitric oxide (NO) in bystander effect was investigated. Human fibroblasts were irradiated with 
-rays (LET: 0.2 keV/
m) or carbon-ion beam (108 keV/m), and then, co-cultured with the non-irradiated cells. After 24 h culture, the survival rates of non-irradiated cells and the concentrations of nitrate, an oxide of NO, in the medium were measured. The survival rates of non-irradiated cells decreased in dose-dependent and radiation quality-independent manners. Negative relationships between survival rates and nitrite concentrations existed, indicating the amounts of produced NO are an important determinant of bystander effects. Next, a reagent producing two molecules of NO in a half-life of 100 min was added in the culture medium. After incubation of 24 h the survival rates of treated cells did not decrease, suggesting NO produced intracellularly has an important role to lead the bystander effect but is not the signal molecule for intercellular communication.
-ray irradiated amino acidsNagata, Natsuki*; Komoda, Seiichi*; Kikuchi, Masahiro; Nakamura, Hideo*; Kobayashi, Yasuhiko; Ukai, Mitsuko*
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 103, 2016/02
no abstracts in English
Yokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Kobayashi, Yasuhiko
Isotope News, (741), p.21 - 25, 2016/01
Our article published on the International Journal of Radiation Biology (2015) was reviewed. We investigated the dependence of the bystander cell-killing effect on radiation dose and quality, and related molecular mechanisms. Human fibroblasts were irradiated with -rays or carbon ions and co-cultured with non-irradiated cells. Survival rates of non-irradiated cells decreased and nitrite concentrations in co-culture medium increased with dose. Their dose responses were similar between -rays and carbon ions. Treatment of the specific nitric oxide (NO) radical scavenger prevented reductions in survival rates of non-irradiated cells. Negative relationships were observed between survival rates and nitrite concentrations. From these results, it was concluded that the bystander cell-killing effect mediated by NO radicals depends on irradiation doses, but not on radiation quality. NO radical production appears to be an important determinant of bystander effects.
Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.
Nihon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00
no abstracts in English
-irradiated bovine liversKikuchi, Masahiro; Kobayashi, Yasuhiko
Shokuhin Shosha, 50(1), p.9 - 12, 2015/10
no abstracts in English
-irradiationKikuchi, Masahiro; Kobayashi, Yasuhiko
Shokuhin Shosha, 50(1), p.3 - 8, 2015/10
no abstracts in English
Kikuchi, Masahiro; Nagata, Natsuki*; Komoda, Seiichi*; Kameya, Hiromi*; Ukai, Mitsuko*; Kobayashi, Yasuhiko
Shokuhin Shosha, 50(1), p.13 - 19, 2015/10
no abstracts in English
Hattori, Yuya; Suzuki, Michiyo; Funayama, Tomoo; Kobayashi, Yasuhiko; Yokoya, Akinari; Watanabe, Ritsuko
Radiation Protection Dosimetry, 166(1-4), p.142 - 147, 2015/09
Times Cited Count：5 Percentile：34.28(Environmental Sciences)Cell-to-cell communication is one of the important factors to understand the mechanisms of radiation-induced responses such as radiation-induced bystander effects at low doses. In the present study, we propose simulation-based analyses of the intercellular signal transmissions between the individual cells in the cellular population. We developed the transmissions of two types of signals, i.e., X is transmitted via culture medium and Y is transmitted via gap junctions based on the diffusion equation. To observe the cell cycle as the response of cell induced by the signals, X and Y, we represented the cell cycle as a virtual clock including several check-point pathways and the cyclic process (G1, S, G2, M phases). The cellular population was divided into the grids (cells), and the signals and the clock were calculated for each grid. The signals, X, Y, were transmitted to the cells and stopped the clocks at the check points. Furthermore, the radiation was modeled as the radiation signal, Z, which affected the clock and the signals, X and Y. We input the radiation signal, Z, to specific cells, and simulated the behaviors of the clock of each cell and signals, X and Y. We will discuss the usefulness of our model for investigating the mechanisms of radiation-induced responses of the cell cycle via cell-to-cell communications.
Tomita, Masanori*; Matsumoto, Hideki*; Funayama, Tomoo; Yokota, Yuichiro; Otsuka, Kensuke*; Maeda, Munetoshi*; Kobayashi, Yasuhiko
Life Sciences in Space Research, 6, p.36 - 43, 2015/07
A radiation-induced bystander response is generally known as a cellular response induced in unirradiated cell by receiving bystander signaling factors released from directly irradiated cells of a cell population. Bystander responses induced by high-LET heavy ions at low fluence are an important problem concerning the health of astronauts in the space environment. Here we set out NO-mediated bystander signal transductions induced by high-LET heavy-ion microbeam irradiation in normal human fibroblasts. Our findings suggest that Akt- and NF-
B-dependent signaling pathway involving COX-2 plays an important role in the NO-mediated high-LET heavy-ion-induced bystander responses. Additionally, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells, which are distinguish form directly irradiated cells.
Kobayashi, Yasuhiko
Kankyo To Kenko, 28(2), p.129 - 139, 2015/06
no abstracts in English
Yokota, Yuichiro; Funayama, Tomoo; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Yasuhiko
International Journal of Radiation Biology, 91(5), p.383 - 388, 2015/05
Times Cited Count：13 Percentile：67.09(Biology)We investigated the dependence of the bystander cell-killing effect on radiation dose and quality, and related molecular mechanisms. Human fibroblasts were irradiated with -rays or carbon ions and co-cultured with non-irradiated cells. Survival rates of non-irradiated cells decreased and nitrite concentrations in culture medium increased with increasing doses. Their dose responses were similar between -rays and carbon ions. Treatment of the specific nitric oxide (NO) radical scavenger prevented reductions in survival rates of non-irradiated cells. Negative relationships were observed between survival rates and nitrite concentrations. From these results, it was concluded that the bystander cell-killing effect mediated by NO radicals in human fibroblasts depends on irradiation doses, but not on radiation quality. NO radical production appears to be an important determinant of -ray- and carbon-ion-induced bystander effects.
Kobayashi, Yasuhiko
Sofuto, Dorinku Gijutsu Shiryo, (175), p.103 - 128, 2015/04
Food irradiation is a technology to treat foods with ionizing radiation such as -rays and electron beams to improve the safety and extends the shelf life of foods by reducing or eliminating microorganisms and insects, and by prevention of sprouting. The food irradiated with ionizing radiation is named as "irradiated food". Many international organizations have approved the safety and usefulness of food irradiation. Ionizing radiation can treat packaged foods and fresh and/or frozen products, and effectively and uniformly treat all portions of foods. Food irradiation is an environmentally friendly technology without usage of chemicals and contributes to the solution of food security and food sanitary problems especially reducing post-harvest losses of foods and controlling food borne illness, as an alternative to chemical fumigation with ethylene oxide and methyl bromide gasses. Japan has a 50 years history of food irradiation research. The "Japanese Research Association for Food Irradiation" has been launched in 1965. It was legally authorized to irradiate potatoes for preventing germination in 1972 and since 1974 irradiation potato has been shipped from the Shihoro-cho Agricultural Cooperative Association in Hokkaido. Recently commercial food irradiation has increased significantly in Asia, however, Japan is now far behind other countries and it is called a "food irradiation underdeveloped country".
Takahashi, Akihisa*; Kubo, Makoto*; Igarashi, Chie*; Yoshida, Yukari*; Funayama, Tomoo; Kobayashi, Yasuhiko; Nakano, Takashi*
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 82, 2015/03
DNA double-strand breaks (DSBs) induced by ionizing radiation pose a major threat to cell survival. The cell can respond to the presence of DSBs, through two major repair pathways: Homologous recombination (HR) and non-homologous end-joining (NHEJ). Higher levels of cell death are induced by high-LET radiation when compared to low-LET radiation, even at the same doses because of less effective or more inefficient DNA repair. In this study, we examine the effects of radiation with different LET values on DNA DSB repair and radiosensitivity. Wild-type cells and HR deficient (but NHEJ proficient) cells exhibited the high RBE values at LET values of 108 keV/ m. The RBE value for each cell type decreased with increasing LET values over 200 keV/m. Although NHEJ proficient cells had an almost constant SER value, NHEJ deficient cells showed a high SER value when compared to NHEJ proficient cells, even with increasing LET values.
Saito, Katsuyo*; Funayama, Tomoo; Kobayashi, Yasuhiko; Murakami, Takashi*
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 83, 2015/03
Epigenetic modifiers, such as histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors, have emerged recently as promising anticancer agents and it has been expected that epigenetic modifiers may enhance the effect of other cancer therapeutics including radiotherapy. Therefore, we investigated whether the use of epigenetic modifiers could sensitize melanoma cells for the heavy-ion therapy. Murine B16F10 melanoma cells were treated with investigational or comparator epigenetic modifier, then exposed to carbon ions of JAEA-Takasaki. After irradiation, the viabilities of cells were evaluated by colony formation assay. Treatment of B16F10 melanoma cells with HDACi trichostatin A (TSA) in combination with heavy-ion radiation provided enhanced inhibition of colony formation. The data suggest that combination of an epigenetic modifier TSA together with heavy-ion therapy may provide improved therapeutic responses in melanoma patients.
Funayama, Tomoo; Yokota, Yuichiro; Suzuki, Michiyo; Sakashita, Tetsuya; Kobayashi, Yasuhiko
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 73, 2015/03
Using a collimating heavy-ion microbeam system, we have explored various effects of heavy-ion hit on biological materials. However, there are limitations of the collimating system in the size of the microbeam spot and in the irradiation speed that cannot be overcome in principle. Thus, we started the development of a focusing microbeam system for target-irradiating individual cells more precisely. In this year, we established the protocol for irradiating "actual" cell sample with scanned beam. In the experiment, the HeLa cells were inoculated on a CR-39 film, then place on the sample stage. The microscopic image of cells was analyzed, and the cells were irradiated with scanned neon microbeam. After irradiation, we found the correspondence of the distribution pattern of the ion hit positions and the -H2AX foci on cell nuclei, indicating rapid and accurate irradiation of individual cells with the focusing heavy-ion microbeam.
Yasuda, Takako*; Oda, Shoji*; Asaka, Tomomi*; Funayama, Tomoo; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Yasuhiko; Mitani, Hiroshi*
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 85, 2015/03
In this present study, we examined the effects of heavy carbon-ions on development in pre-implantation period utilizing medaka blastula stage embryos (st. 11: blastderm diameter is about 500 m). We performed targeted irradiation by carbon-ion micro-beam (diameters of 120, 180 m) to a central parts of blastoderm and observed the abnormalities during development compared with whole-body irradiated embryos. As a results, retardation and characteristic malformed eyes were observed during development when blastoderm cells were partially irradiated, However, more than half of 50 Gy-irradiated embryos (area size=120 m diameter) could hatch normally in contrast to all embryos with 2 Gy of whole-body irradiation being lethal before hutching.
Yoshida, Yukari*; Mizohata, Kensuke*; Matsumura, Akihiko*; Isono, Mayu*; Yako, Tomoko*; Nakano, Takashi*; Funayama, Tomoo; Kobayashi, Yasuhiko; Kanai, Tatsuaki*
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 81, 2015/03
In the clinical application of carbon-ion (C-ion) radiation therapy in Japan, different RBE values of carbons have been used for clinical and biological endpoints. The biological RBE (bRBE) was estimated by a method that is based on the linear-quadratic (LQ) model, and was defined 
at the 10% surviving fraction of human salivary gland (HSG) tumor cells. However, many of biological parameters, that is, type of tissues, different sort of cells, oxygenation levels, and all, could affect radiosensitivity. Thus, normal human dermal fibroblasts (NHDF) cells were exposed to C-ion beams at Gunma University (10-80 keV/micrometer) and TIARA (108 and 158 keV/micrometer). The surviving fractions were analyzed with colony formation assays. The experimental RBE (eRBE) values were estimated from the radiation dose survival curve fitted by LQ model, and defined .
C and 
HeAkeo, Kiyoshi*; Funayama, Tomoo; Kobayashi, Yasuhiko; Akeo, Yoko*
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 80, 2015/03
It is known that superoxide dismutases (SOD) are a class of enzymes that catalyze the dismutation of superoxide into oxygen and hydrogen peroxide. Ionizing radiation is known to induce oxidative stress through generation of reactive oxygen species resulting in imbalance of the pro-oxidant and antioxidant in the cells, which is suggested to culminate in cell death. Therefore, we measured the activity of SOD in human RE cells exposed to the He- and C-ion beam. The cells collected at 0, 4, 8, and 24 hr after irradiation were extracted by adding the SOD assay buffer to the pellets, and lysed by several cycles of freezing and thawing. The activity of SOD was measured using a modification of the luminol assay. SOD activity decreased according to duration time after irradiation of He-ion, however, in case of C-ion, it increased at 24 hr after irradiation. The result suggested that that there were the differences of the effects by irradiation on SOD activity between He- and C-ion.
Matsumoto, Hideki*; Tomita, Masanori*; Otsuka, Kensuke*; Hatashita, Masanori*; Maeda, Munetoshi*; Funayama, Tomoo; Yokota, Yuichiro; Suzuki, Michiyo; Sakashita, Tetsuya; Ikeda, Hiroko; et al.
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 76, 2015/03
The objective of this project is to elucidate molecular mechanisms for the induction of radioadaptive response through radiation-induced bystander responses induced by irradiation with heavy ion microbeams in JAEA. We found that the adaptive response was induced by Ar (520 MeV 
Ar
) microbeam-irradiation of a limited number of cells, followed by the broad beam-irradiation and that the adaptive response was almost completely suppressed by the addition of carboxy-PTIO, as a nitric oxide (NO) scavenger. In addition, we found several genes induced specifically and preferentially when radioadaptive response could be induced. We confirmed that 
expression was specifically induced only when radioadaptive response could be induced. Our findings strongly suggested that radioadaptive response can be induced by NO-mediated bystander responses evoked by irradiation with heavy ion microbeams.
