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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.
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.
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：7 Percentile：60.95(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.
mutants to microbeam irradiationSakashita, Tetsuya; Suzuki, Michiyo; Hattori, Yuya; Ikeda, Hiroko; Muto, Yasuko*; Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Shirai, Kana*; Kobayashi, Yasuhiko
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 74, 2015/03
An increasing body of data indicates that ionizing radiation affects the nervous system and alters its function. Recently, we reported that chemotaxis of during the salt chemotaxis learning (SCL), that is conditioned taste aversion to NaCl, was modulated by carbon ion irradiation, i.e. accelerated decrease in chemotaxis to NaCl during the SCL. However, we had no direct evidence for the interaction of ionizing radiation with the central neuronal tissue (nerve ring) in . Microbeam irradiation is useful to analyze direct radiation effects at a cellular or tissue level. Thus, we applied the microbeam irradiation of the nerve ring and examined the effect on the SCL.
Suzuki, Michiyo; Hattori, Yuya; Sakashita, Tetsuya; Funayama, Tomoo; Yokota, Yuichiro; Ikeda, Hiroko; Kobayashi, Yasuhiko
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 88, 2015/03
Yokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Sakashita, Tetsuya; Suzuki, Michiyo; Kobayashi, Yasuhiko
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 75, 2015/03
We investigated the bystander effect induced by -rays or carbon ions and analyzed the role of nitric oxide (NO) in the effect. Normal human fibroblasts were used. Cells inoculated on a porous membrane were irradiated with varying doses of -rays or carbon ions. Irradiated cells were then non-contact co-cultured with non-irradiated cells for 24 h. After co-culture, the survival rates of non-irradiated bystander cells co-cultured with irradiated cells decreased with increasing dose and bottomed out at 0.5 Gy or higher doses. This indicates that the bystander effect is dependent on irradiation dose but independent of radiation quality. Next, a specific NO scavenger c-PTIO was added to the culture medium during irradiation and co-culture. This treatment prevented the reduction in survival rates of bystander cells, clearly indicating that NO has an important role in the bystander effect.
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.
locus in normal human fibroblasts induced by C-, Ne- and Ar-ion microbeamsSuzuki, Masao*; Funayama, Tomoo; Yokota, Yuichiro; Muto, Yasuko*; Suzuki, Michiyo; Ikeda, Hiroko; Hattori, Yuya; Kobayashi, Yasuhiko
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 78, 2015/03
We have been studying the radiation-quality dependent bystander cellular effects, such as cell killing, mutation induction and chromosomal damage, using heavy-ion microbeams with different ion species. This year we focused on the ion-species dependent bystander mutagenic effect on locus in normal human fibroblasts. The confluent culture were irradiated using a 256 (16
16)-cross-stripe method using C, Ne and Ar microbeam. Gene mutation on locus was detected with 6-thioguanine resistant clones. The mutation frequency in cells irradiated with C-ion microbeams was 6 times higher than that of non-irradiated control cells and of the sample treated with specific inhibitor of gap-junction cell-to-cell communication. On the other hand, no enhanced mutation frequencies were observed in cells irradiated with either Ne- or Ar-ion microbeams. There is clear evidence that the bystander mutagenic effect via gap-junction communication depends on radiation quality.
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.
Suzuki, Masao*; Autsavapromporn, N.*; Usami, Noriko*; Funayama, Tomoo; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Suzuki, Michiyo; Ikeda, Hiroko; Hattori, Yuya; et al.
Journal of Radiation Research, 55(Suppl.1), P. i54, 2014/03
Autsavapromporn, N.*; Suzuki, Masao*; Funayama, Tomoo; Usami, Noriko*; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Katsumi*; Kobayashi, Yasuhiko; et al.
Radiation Research, 180(4), p.367 - 375, 2013/10
Times Cited Count：50 Percentile：90.17(Biology)We investigated the role of gapjunction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from X ray, carbon ion, neon ion or argon ion microbeams in the presence or absence of an inhibitor of GJIC. After 4 h incubation, the cells were assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. The results highlight the important role of radiation quality and dose in the observed effects.
Amano, Hikaru; Takahashi, Tomoyuki*; Uchida, Shigeo*; Matsuoka, Shungo*; Ikeda, Hiroshi*; Hayashi, Hiroko*; Kurosawa, Naohiro*
Journal of Nuclear Science and Technology, 40(11), p.975 - 979, 2003/11
Times Cited Count：2 Percentile：19.75(Nuclear Science & Technology)MOGRA is a migration prediction code for toxic ground additions including radioactive materials in a terrestrial environment. MOGRA consists of computational codes that are applicable to various evaluation target systems, and can be used on personal computers. The computational code has the dynamic compartment analysis block, GUI for computation parameter settings and results displays, data bases. The compartments are obtained by classifying various natural environments into groups that exhibit similar properties. A hypothetical combination of land usage was supposed to check the function of MOGRA. The land usage was consisted from cultivated lands, forests, uncultivated lands, urban area, river, and lake. Each land usage has its own inside model which is basic module. Also supposed was homogeneous contamination of the surface land from atmospheric deposition of 
Cs (1.0 Bq/m
). The system analyzed the dynamic changes of Cs concentrations in each compartment, fluxes from one compartment to another compartment.
Amano, Hikaru; Takahashi, Tomoyuki*; Uchida, Shigeo*; Matsuoka, Shungo*; Ikeda, Hiroshi*; Hayashi, Hiroko*; Kurosawa, Naohiro*
JAERI-Conf 2003-010, p.32 - 36, 2003/09
MOGRA (Migration Of GRound Additions) is a migration prediction code for toxic ground additions including radioactive materials in a terrestrial environment. MOGRA consists of computational codes that are applicable to various evaluation target systems, and can be used on personal computers. The computational code has the dynamic compartment analysis block at its core, the graphical user interface (GUI) for computation parameter settings and results displays, data files and so on. The compartments are obtained by classifying various natural environments into groups that exhibit similar properties. MOGRA has varieties of databases, which consist of radionuclides decay chart, distribution coefficients between solid and liquid, transfer factors from soil to plant, transfer coefficients from feed to beef and milk, concentration factors, and age dependent dose conversion factors for many radionuclides. Here the status of development of MOGRA is presented.
Amano, Hikaru; Takahashi, Tomoyuki*; Uchida, Shigeo*; Matsuoka, Shungo*; Ikeda, Hiroshi*; Hayashi, Hiroko*; Kurosawa, Naohiro*
JAERI-Conf 2003-010, p.112 - 121, 2003/09
The functionality of MOGRA is being verified by applying it in the analyses of the migration rates of radioactive substances from the atmosphere to soils and plants and flow rates into the rivers. This has been achieved by also taking their mode classifications into consideration. In this report, a hypothetical combination of land usage was supposed to check the function of MOGRA. The land usage was consisted from cultivated lands, forests, uncultivated lands, urban area, river, and lake. Each land usage has its own inside model which is basic module. Also supposed was homogeneous contamination of the surface land from atmospheric deposition of Cs-137 (1.0 Bq/m). The system can analyze the dynamic changes of Cs-137 concentrations in each compartment, fluxes from one compartment to another compartment.
Takahashi, Tomoyuki*; Amano, Hikaru; Uchida, Shigeo*; Ikeda, Hiroshi*; Matsuoka, Shungo*; Hayashi, Hiroko*; Kurosawa, Naohiro*
Kankyo Eisei Kogaku Kenkyu, 17(3), p.340 - 344, 2003/07
no abstracts in English
Yokota, Yuichiro; Funayama, Tomoo; Muto, Yasuko; Ikeda, Hiroko; Kobayashi, Yasuhiko
no journal, ,
The purpose of this study is to clear a time dependency of carbon-ion-induced bystander cell-killing effect. Thus, we irradiated normal human fibroblasts with carbon ion microbeam (LET=103 keV/m), broad beam (108 keV/m) and -rays (0.2 keV/m). Survival rate of bystander cells was measured after 6-24 h co-culture with irradiated cells. The ratio of irradiated and bystander cells was <0.0005:1 in microbeam irradiation and 0.5:1 in broad beam and -ray irradiation, respectively. In microbeam-irradiated samples, the survival rate of bystander cells did not change at 6 h but decreased to about 85% of control at 24 h. In 0.13-Gy broad beam and 0.5-Gy -ray irradiated samples, the survival rate of bystander cells decreased to 80-90% of control at 6 h or later. From these results, it is found that bystander cell-killing effect is delayed when irradiated cells are extremely less than bystander cells.
Ikeda, Hiroko; Yokota, Yuichiro; Funayama, Tomoo; Muto, Yasuko; Kanai, Tatsuaki*; Kobayashi, Yasuhiko
no journal, ,
The purpose of this study is to detect bystander effect between normal fibroblasts and lung cancer cells with different p53 status and to elucidate its mechanisms. In the study, we used human lung normal fibroblasts WI-38 line and human lung cancer cells H1299/wtp53 line that can produce normal p53 proteins in their DNA damage response. We irradiated cells with carbon-ion broad beams (18.3 MeV/u, LET = 108 keV/m; Dose = 0.5 Gy) or -rays (Dose = 0.5 Gy), then calculated survival rates of bystander cells after 6 or 24 hours cocultute of irradiated and non-irradiated cells. When we cocultured irradiated H1299/wtp53 cells with non-irradiated WI-38 cells, it was found that survival rates of WI-38 cells were not decreased at all. Consequently, it was suggested that bystander factors were not released from irradiated H1299/wtp53 cells.
Muto, Yasuko; Funayama, Tomoo; Yokota, Yuichiro; Ikeda, Hiroko; Kobayashi, Yasuhiko
no journal, ,
no abstracts in English
Ikeda, Hiroko; Yokota, Yuichiro; Funayama, Tomoo; Muto, Yasuko; Kanai, Tatsuaki*; Kobayashi, Yasuhiko
no journal, ,
In this study, we investigated radiation-induced bystander effects between normal fibroblasts and cancer cells to elucidate the responses between normal tissues and tumor in heavy-ion radiotherapy. In our experiments, human lung normal fibroblasts WI-38 line and human lung cancer cells H1299/wtp53 line which is genetically modified to produce normal p53 proteins in their DNA damage response were used. Cells were irradiated with carbon-ion broad beams (LET = 108 keV/m, Dose = 0.5 Gy) or Co-60 -rays (LET = 0.2 keV/m, Dose = 0.5 Gy), then survival rates of bystander cells after 6- or 24-hours co-culture with irradiated cells were calculated using colony formation assay. It was consequently found that survival rates of non-irradiated WI-38 cells increased when the cells were co-cultured with irradiated H1299/wtp53 cells. From this result, we conclude that some signals are released from irradiated H1299/wtp53 cells to promote cell adhesion and growth of bystander cells.
Yokota, Yuichiro; Funayama, Tomoo; Muto, Yasuko; Ikeda, Hiroko; Kobayashi, Yasuhiko
no journal, ,
In this study, we investigated a time dependency of bystander effect. In experiments, we irradiated normal human fibroblasts with carbon-ion microbeam (LET=103 keV/m, 10 particles/irradiated site), carbon-ion broad beam (0.13 Gy) and Co-60 -rays (0.2 keV/m, 0.5 Gy). In broad-beam and -ray irradiation, irradiated cells and non-irradiated cells were co-cultured with porous membrane. The ratio of irradiated cells and bystander cells was 1:20,000 in microbeam irradiation and 1:2 in broad-beam and -ray irradiation, respectively. In microbeam-irradiated samples, the survival rate of bystander cells did not change at 6 h but decreased to about 80% at 24 h. In broad-beam and -ray irradiated samples, the survival rate of bystander cells decreased to 80 to 90% at 6 h or later. From these results, it was found that bystander effect is dependent on time after irradiation and number of irradiated cells.
