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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：11 Percentile：64.26(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.
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.
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.
Autsavapromporn, N.*; Plante, I.*; Liu, C.*; Konishi, Teruaki*; Usami, Noriko*; Funayama, Tomoo; Azzam, E.*; Murakami, Takeshi*; Suzuki, Masao*
International Journal of Radiation Biology, 91(1), p.62 - 70, 2015/01
Times Cited Count：31 Percentile：93.37(Biology)Radiation-induced bystander effects have important implications in radiotherapy. Their persistence in normal cells may contribute to risk of health hazards, including cancer. This study investigates the role of radiation quality and gap junction intercellular communication (GJIC) in the propagation of harmful effects in progeny of bystander cells. Confluent human skin fibroblasts were exposed to microbeam radiations with different linear energy transfer (LET) by which 0.036
0.4% of the cells were directly targeted by radiation. Following 20 population doublings, the cells were harvested and assayed for micronucleus formation, gene mutation and protein oxidation. The results showed that expression of stressful effects in the progeny of bystander cells is dependent on LET.
Sakamoto, Yukio; Sato, Osamu*; Tsuda, Shuichi; Yoshizawa, Nobuaki*; Iwai, Satoshi*; Tanaka, Shunichi; Yamaguchi, Yasuhiro
JAERI 1345, 103 Pages, 2003/01
no abstracts in English
; Takahashi, Fumiaki; Sawahata, Tadahiro*; *; *; Murayama, Takashi
JAERI-Tech 99-004, 89 Pages, 1999/02
no abstracts in English
Sasuga, Tsuneo; Kudo, Hisaaki; Seguchi, Tadao
Polymer, 40, p.5095 - 5102, 1999/00
Times Cited Count：25 Percentile：68.2(Polymer Science)no abstracts in English
Yoshizawa, Michio; Yamaguchi, Yasuhiro
IRPA9: 1996 International Congress on Radiation Protection, Proceedings, 3, p.41 - 43, 1996/00
no abstracts in English
; ; ;
JAERI-M 84-232, 28 Pages, 1985/01
no abstracts in English
Yokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Sakashita, Tetsuya; Suzuki, Michiyo; Kobayashi, Yasuhiko
no journal, ,
Here, we investigate bystander effect. Normal human fibroblast WI-38 cells were irradiated with carbon ions or -rays. Irradiated cells and non-irradiated cells were co-cultured. The survival rates of bystander cells decreased with dose at lower than 0.5 Gy and bottomed out at around 80%. In addition, the survival rates of bystander cells were not significantly different between carbon ions and -rays at the same doses. These indicated the bystander cell-killing effect depends on irradiation dose but not on radiation quality. c-PTIO, a specific scavenger of nitric oxides (NO), suppressed the reduction of survival rates of bystander cells, showing NO has an important role to induce the bystander effect. The concentrations of nitrite, an oxide of NO, were measured. There were negative relationships between the survival rates of bystander cells and the nitrite concentrations of the medium. NO released to the medium maybe an important factor related to the bystander effect.
Autsavapromporn, N.*; Plante, I.*; Liu, C.*; Konishi, Teruaki*; Usami, Noriko*; Funayama, Tomoo; Azzam, E.*; Murakami, Takeshi*; Suzuki, Masao*
no journal, ,
Confluent human skin fibroblasts (NB1RGB) were exposed to various types of microbeam with a different linear energy transfer (LET) at mean absorbed doses 0.4 Gy, wherein 0.036-0.4% of the cells were targeted by IR. Following 20 populations post-irradiation, the cells were harvested and assayed for micronucleus formation, mutation assay and protein oxidation. The progeny of bystander cells exposed to X rays and protons showed the persistence of oxidative stress, and correlate with the increased micronucleus formation and mutant fraction. However, such effects were not observed after irradiation by carbon ions. Interestingly, inhibition of GJIC mitigated the damaging effects in the progeny of bystander cells exposed to protons and carbon ions but not X rays. These data show carbon ions can reduce cancer risk after microbeam irradiation compared with X rays or protons, and GJIC may be a critical mediator in the observed effect.
Nagaishi, Ryuji
no journal, ,
no abstracts in English
Nagaishi, Ryuji; Kuwano, Ryo*; Matsumura, Taichi
no journal, ,
Different from monochromatic photons such as Co-60 -rays, Bremsstrahlung and X-rays with continuous energies provide photons with different radiation quality (RQ) into water, dependent on the width of water layer. Since the photons with different RQ further give different primary yields (G-value) of water radiolysis, the effect of RQ (LET) on G-values would be important in experiments with photons with continuous energies. In this study, the experiments using X-rays simulating Bremsstrahlung from 
-ray and secondary electrons were conducted with changing the tube voltage and water width to clarify the LET effect on the X-ray radiolysis of water.
Ito, Tatsuya; Kuwano, Ryo*; Nagaishi, Ryuji
no journal, ,
Unlike monochromatic photons such as Co-60 gamma rays, continuous energy (spectrum) photons such as bremsstrahlung and X-rays give photons of different radiation quality (energy, spectrum) into water. The radiolysis of water by these photons gives different yields (G-values) and patterns of products. Therefore, since it is important to evaluate their radiation quality (LET) effects in experiments using these photons, using an X-ray irradiation apparatus, we have evaluated dependences of dose, LET and radiolysis G-value on water layer thickness and tube voltage. In this report, we have developed (improved) a method for evaluating molecular formation with high accuracy, such as by fabricating a new glass irradiation vessel, and mainly evaluated the effect of tube voltage (maximum incident energy) on molecular formation. Based on the results, we discussed the LET effect.
Ito, Tatsuya; Kuwano, Ryo*; Nagaishi, Ryuji
no journal, ,
Unlike monochromatic photons such as Co-60 gamma rays, continuous energy (spectrum) photons such as bremsstrahlung and X-rays give photons of different radiation quality (energy, spectrum) into water. The radiolysis of water by these photons gives different yields (G-values) and patterns of products. Therefore, since it is important to evaluate their radiation quality (LET) effects in experiments using these photons, using an X-ray irradiation apparatus, we have evaluated dependences of dose, LET and radiolysis G-value on water layer thickness and tube voltage. In this report, we have developed a method for evaluating molecular formation with high accuracy, such as by fabricating a new glass irradiation vessel, and mainly evaluated the effect of tube voltage on molecular formation. Based on the results, we discussed the LET effect. This presentation is a commemorative lecture given at the general meeting of the Department of Water Chemistry, AESJ, for receiving the Presentation Award.
Nagaishi, Ryuji; Ito, Tatsuya; DiPrete, D.*; Fellinger, A.*
no journal, ,
In the 1F decommissioning, the retrieval of fuel debris is planned, and then the importance of water radiolysis by alpha-rays becomes increasing in the debris storage more than 10 years after the accident. When alpha-emitting nuclides are contained in insoluble solid materials, the alpha-rays slowdown in the materials, and the energies of alpha-rays escaped from the materials become lower and continuous. The energy spectrum varies with the type and size of materials, and this spectral difference affects the pattern and magnitude of G-value of water radiolysis. Therefore, in order to study the alpha-radiolysis, it is necessary to measure and evaluate the material-dependent spectrum. In this study, we used solid material powders containing plutonium 239 (Pu-239) and measured the alpha-ray spectrum from the powders to estimate the linear energy transfer (LET) of alpha-rays. It was further compared with that when the nuclide is a dissolved species in water.
