Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 46

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

The Bystander cell-killing effect mediated by nitric oxide in normal human fibroblasts varies with irradiation dose but not with radiation quality

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 $$gamma$$-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 $$gamma$$-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 $$gamma$$-ray- and carbon-ion-induced bystander effects.

Journal Articles

Responses of the salt chemotaxis learning in ${it C. elegans}$ mutants to microbeam irradiation

Sakashita, 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 ${it C. elegans}$ 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 ${it C. elegans}$. Microbeam irradiation is useful to analyze direct radiation effects at a cellular or tissue level. Thus, we applied the microbeam irradiation of the ${it C. elegans}$ nerve ring and examined the effect on the SCL.

Journal Articles

Ion-species dependent bystander mutagenic effect on ${it HPRT}$ locus in normal human fibroblasts induced by C-, Ne- and Ar-ion microbeams

Suzuki, 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 ${it HPRT}$ locus in normal human fibroblasts. The confluent culture were irradiated using a 256 (16$$times$$16)-cross-stripe method using C, Ne and Ar microbeam. Gene mutation on ${it HPRT}$ 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.

Journal Articles

Medaka blastoderm cells are capable of compensating the injured cells irradiated by carbon-ion micro-beam

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 $$mu$$m). We performed targeted irradiation by carbon-ion micro-beam (diameters of 120, 180 $$mu$$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 $$mu$$m diameter) could hatch normally in contrast to all embryos with 2 Gy of whole-body irradiation being lethal before hutching.

Journal Articles

Radiation-quality-dependent bystander effects induced by the microbeams with different radiation sources

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

Journal Articles

Gap junction communication and the propagation of bystander effects induced by microbeam irradiation in human fibroblast cultures; The Impact of radiation quality

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.

Journal Articles

Involvement of bystander effect in suppression of the cytokine production induced by heavy-ion broad beams

Muto, Yasuko; Funayama, Tomoo; Yokota, Yuichiro; Kobayashi, Yasuhiko

International Journal of Radiation Biology, 88(3), p.258 - 266, 2012/03

 Times Cited Count:11 Percentile:69.17(Biology)

Journal Articles

Heavy ion irradiation induces autophagy in irradiated C2C12 myoblasts and their bystander cells

Hino, Mizuki*; Hamada, Nobuyuki*; Tajika, Yuki*; Funayama, Tomoo; Morimura, Yoshihiro*; Sakashita, Tetsuya; Yokota, Yuichiro; Fukamoto, Kana*; Muto, Yasuko; Kobayashi, Yasuhiko; et al.

Journal of Electron Microscopy, 59(6), p.495 - 501, 2010/12

 Times Cited Count:13 Percentile:61.02(Microscopy)

Journal Articles

Immune response pathways in human keratinocyte (HaCaT) cells are induced by ultraviolet B via p38 mitogen-activated protein kinase activation

Muto, Yasuko; Tsukimoto, Mitsutoshi*; Homma, Takujiro*; Kojima, Shuji*

Journal of Health Science, 56(6), p.675 - 683, 2010/00

 Times Cited Count:3 Percentile:10.22(Toxicology)

Oral presentation

The Telomerase inhibitor MST-312 additively sensitizes HeLa cells to carbon-ion irradiation

Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Sakashita, Tetsuya; Suzuki, Michiyo; Muto, Yasuko; Kobayashi, Yasuhiko

no journal, , 

It is needed to accumulate the more evidence for combined therapy between heavy ions and chemical agents for overcoming refractory tumors. Here, we investigate a combination effect of carbon-ion irradiation and the telomerase inhibitor MST-312 treatment in human cervical cancer HeLa cells by means of a colony formation assay. Cells were cultured for 24 h with or without 1 $$mu$$M MST-312, and then, irradiated with carbon ions (LET: 110 keV/$$mu$$m) and $$gamma$$-rays. MST-312 treatment additively decreased the survival of irradiated cells. Irradiation and MST-312 treatment might inactivate the clonogenic potential of tumor cells through independent mechanisms. The doses needed to reduce the survival of irradiated cells to 10% were decreased by MST-312 treatment from 1.2 Gy to 0.5 Gy in carbon-ion irradiation and from 5.4 Gy to 4.0 Gy in $$gamma$$-ray irradiation, respectively. MST-312 pre-treatment may reduce the doses needed for a curative effect in heavy ion radiotherapy.

Oral presentation

Carbon-ion microbeam induces behavioral change in the salt chemotaxis learning of ${it C. elegans}$

Sakashita, Tetsuya; Suzuki, Michiyo; Muto, Yasuko; Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Fukamoto, Kana*; Kobayashi, Yasuhiko

no journal, , 

To investigate the effects on the neuronal tissue (a nerve ring), we used the heavy-ion microbeam system. Well-fed adults of ${it C. elegans}$ grown on the plate spread with the ${it E. coli OP50}$ were used in all experiments. Anesthetized animals were irradiated locally with carbon-ion microbeams that were extracted into the air through an aperture. Immediately after microbeam irradiation, chemotaxis to NaCl of exposed animals was measured. Microbeam irradiation experiments in the both areas showed no significant effects on the ability of the salt chemotaxis learning. It indicates that the salt chemotaxis learning in ${it C. elegans}$ is not affected by carbon-ion induced damage in Head or Tail area; possibly such as DNA strand breaks. Moreover, to challenge during-learning irradiation, we attempt the development of live-targeting system for non-paralyzed ${it C.elegans}$ using the micro-device. We will discuss on the new approach.

Oral presentation

Heavy-ion microbeam irradiation induces bystander effect in human THP-1 macrophages

Muto, Yasuko; Funayama, Tomoo; Yokota, Yuichiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

Heavy-ion microbeam irradiation induces bystander effect in human THP-1 macropages

Muto, Yasuko; Funayama, Tomoo; Yokota, Yuichiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

Heavy-ion microbeam irradiation induces bystander effect in human THP-1 macropages

Muto, Yasuko; Funayama, Tomoo; Yokota, Yuichiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

Exploration of the effective site for radiation response of the salt chemotaxis learning in ${it C. elegans}$ using heavy-ion microbeam

Sakashita, Tetsuya; Suzuki, Michiyo; Muto, Yasuko; Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Fukamoto, Kana*; Kobayashi, Yasuhiko

no journal, , 

An increasing body of data indicates that ionizing radiation affects the nervous system and alters its function. Chemotaxis of ${it C. elegans}$ during the salt chemotaxis learning was modulated by $$gamma$$ irradiation. Our preliminary results showed the similar response of the salt chemotaxis learning to whole-body carbon-ion irradiation. However, we have no direct evidence for the interaction of ionizing radiation with the central neuronal tissue (nerve ring) in ${it C. elegans}$. Microbeam irradiation is useful to analyze direct radiation effects at a cellular or tissue level. Thus, we investigate the effects of energetic carbon ion on the salt chemotaxis learning of ${it C. elegans}$ using microbeam irradiation to its nerve ring and also combined effects with anesthesia that inhibits nerve function.

Oral presentation

A Study on quantitative analysis of heavy-ion-induced DNA double-strand breaks; A Problem of conventional protocol using pulsed-field gel electrophoresis

Yokota, Yuichiro; Funayama, Tomoo; Muto, Yasuko; Sakashita, Tetsuya; Kikuchi, Masahiro; Kobayashi, Yasuhiko

no journal, , 

Heavy-ion-induced DNA double-strand breaks (DSBs) have been focused to reveal the underlying mechanism of the well-known findings that relative biological effectiveness is greater in high-LET heavy ions than in low-LET radiation. Since 1990s, DSBs have been quantified with pulsed-field gel electrophoresis (PFGE) technology. In conventional studies, DNA preparation from irradiated cells was performed in agarose plugs for avoiding excess DNA fragmentation during experimental procedures. However, we have found here that DNA fragments are partly lost from the agarose plug during DNA preparation. This makes difficult to reveal the total DSB yield in irradiated cells.

Oral presentation

Carbon-ion-induced bystander cell-killing effect depends on time after irradiation

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/$$mu$$m), broad beam (108 keV/$$mu$$m) and $$gamma$$-rays (0.2 keV/$$mu$$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 $$gamma$$-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 $$gamma$$-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.

Oral presentation

Study on bystander effects induced by carbon-ion beams between normal fibroblasts and lung cancer 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/$$mu$$m; Dose = 0.5 Gy) or $$gamma$$-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.

Oral presentation

Heavy-ion microbeam irradiation induces bystander effect in human THP-1 macropages

Muto, Yasuko; Funayama, Tomoo; Yokota, Yuichiro; Ikeda, Hiroko; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

46 (Records 1-20 displayed on this page)