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Sakashita, Tetsuya; Hamada, Nobuyuki*; Kawaguchi, Isao*; Ouchi, Noriyuki; Hara, Takamitsu*; Kobayashi, Yasuhiko; Saito, Kimiaki
no journal, ,
Clonogenicity gives important information about the cellular reproductive potential following ionizing irradiation. We firstly plotted the experimentally determined colony size distribution of abortive colonies in irradiated normal human fibroblasts, and found the linear relationship on the log-log plot. By applying the simple model of branching processes to the linear relationship, we found the persistent reproductive cell death (RCD) over several generations following irradiation. To verify the estimated probability of RCD, abortive colony size distribution (
16 cells/colony) and the surviving fraction were simulated by the Monte Carlo computational approach. Radiation-induced RCD (i.e. excess probability) lasted over 16 generations and mainly consisted of two components in the early and late phases. These results suggest that short-term RCD is critical to the abortive colony size distribution, and long-lasting RDC is important for the dose response of the surviving fraction.
Suzuki, Michiyo; Hattori, Yuya; Sakashita, Tetsuya; Funayama, Tomoo; Yokota, Yuichiro; Ikeda, Hiroko; Kobayashi, Yasuhiko
no journal, ,
no abstracts in English
Hattori, Yuya; Suzuki, Michiyo; Funayama, Tomoo; Kobayashi, Yasuhiko; Yokoya, Akinari; Watanabe, Ritsuko
no journal, ,
no abstracts in English
Sakamoto, Ayako; Akita, Mutsumi; Endo, Masaki*; Toki, Seiichi*
no journal, ,
no abstracts in English
Noguchi, Miho; Kanari, Yukiko; Fujii, Kentaro; Yokoya, Akinari
no journal, ,
no abstracts in English
Oda, Shoji*; Yasuda, Takako*; Asaka, Tomomi*; Mitani, Hiroshi*; Ikeda, Hiroko; Muto, Yasuko*; Yokota, Yuichiro; Suzuki, Michiyo; Funayama, Tomoo; Kobayashi, Yasuhiko
no journal, ,
The method for targeting and irradiating the testis of fry and adult of Medaka fish using carbon-ion microbeam was established. To irradiate the testis of the fry, a transgenic Medaka that expresses GFP protein specifically in its testis was used. The position of the testis was observed under fluorescent microscopy and then the testis was targeted and irradiated with carbon ion microbeam. To irradiate the testis of the adult Medaka, a adult male of p53 knock out transgenic fish was used. The microbeam was irradiated on the estimated testis position; thereafter the success of irradiation was confirmed by the induction of testis-ova, which is known as induced by the radiation of testis in p53 knock out fish.
Suzuki, Masao*; Autsavapromporn, N.*; Funayama, Tomoo; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Suzuki, Michiyo; Hattori, Yuya; Sakashita, Tetsuya; Kobayashi, Yasuhiko; et al.
no journal, ,
To determine signal transduction factors that are expected to be secreted from microbeam-irradiated cells, the time course analysis of cell killing effect in microbeam irradiated cell population was carried out. To irradiate cell with heavy-ion microbeam, a collimating heavy-ion microbeam system of JAEA-Takasaki was used. After microbeam irradiation, the samples were incubated for 0.5, 3, 24 hours respectively, and the cell killing effect of the microbeam irradiation were measured by colony formation assay. The result suggested that some factors, which induces bystander cell killing, were secreted after argon-ion microbeam, and the factor can be inhibited by the addition of gap-junction inhibitor and DMSO, but not by the ascorbic acid.
Funayama, Tomoo; Yokota, Yuichiro; Sakashita, Tetsuya; Suzuki, Michiyo; Ikeda, Hiroko; Kobayashi, Yasuhiko
no journal, ,
Target irradiation of individual cells using microbeam is a useful means to investigate the mechanism of heavy-ion radiation action. In JAEA-Takasaki, there are two microbeam systems for biological study: the collimating heavy-ion microbeam system, and the focusing heavy-ion microbeam system. The collimating microbeam system was developed and installed at mid 1990's and has been utilized for various biological studies. To explore the behaviors of the whole cell population after bystander irradiation, an integration of live-cell imaging technology into the cell targeting-and-observation system of the collimating microbeam system is under development. On the other hand, we established a method to irradiate finer heavy-ion microbeam from focusing heavy-ion microbeam system on individual HeLa cells. For rapid and accurate delivery of heavy-ions to the individual cells, a method for targeting cells with scanned beam is under development.
-rays; Its dependencies on radiation quality and post-irradiation culture timeYokota, Yuichiro; Funayama, Tomoo; Ikeda, Hiroko; Muto, Yasuko*; Suzuki, Michiyo; Sakashita, Tetsuya; Kobayashi, Yasuhiko
no journal, ,
We investigate radiation-induced bystander effect to elucidate its mechanism. Cells irradiated with up to 2 Gy of carbon ions (108 keV/
m) and -rays (0.2 keV/m) were co-cultured with non-irradiated cells in the above and below of porous membrane. Non-irradiated bystander cells decreased their survival at 6 and 24 h in co-culture when 33% of cell population was irradiated. In addition, survival reduction of bystander cells was increased with dose and saturated at 0.5 Gy. The dose responses were similar between carbon ions and -rays, indicating that bystander effects were partly dependent on dose but independent of radiation quality. Next, 0.001% of cell population was irradiated with carbon ion and neon ion (380 keV/m) microbeams. Bystander cells decreased their survival at 24 h but not at 6 h in co-culture. From these, it was estimated that bystander effects were also dependent on the fraction of irradiated cells.
Sakamoto, Yuka; Noguchi, Miho; Fujii, Kentaro; Yokoya, Akinari
no journal, ,
no abstracts in English
Kanari, Yukiko; Noguchi, Miho; Fujii, Kentaro; Yokoya, Akinari
no journal, ,
no abstracts in English
Ikeda, Hiroko; Yokota, Yuichiro; Funayama, Tomoo; Kanai, Tatsuaki*; Kobayashi, Yasuhiko
no journal, ,
The purpose of this research is to compare bystander responses between different type cells and same type cells, and is to clarify their influence on heavy-ion radiotherapy. In our experiments, human lung normal fibroblasts WI-38 line and human lung cancer cells H1299/wt
line were used. Cells were irradiated with carbon-ion broad beams (WI-38:0.13 Gy, H1299/wt:0.5 Gy), then survival rates of bystander cells after 6- or 24-hours co-culture with irradiated cells was calculated using colony formation assay. Consequently, it is suggested that there is a large difference in heavy-ion induced bystander responses via medium between the different type cells and the same type cells.
Kaminaga, Kiichi; Narita, Ayumi; Noguchi, Miho; Yokoya, Akinari
no journal, ,
no abstracts in English