@article{oai:repo.qst.go.jp:00046598,
 author = {Masunaga, Shinichiro and Sakurai, Yoshinori and Tanaka, Hiroki and Hirayama, Ryoichi and Matsumoto, Yoshitaka and Uzawa, Akiko and Suzuki, Minoru and Kondo, Natsuko and Maruhashi, Akira and Ono, Koji and 平山 亮一 and 松本 孔貴 and 鵜澤 玲子 and 丸橋 晃 and 小野 公二},
 issue = {1021},
 journal = {British Journal of Radiology},
 month = {Mar},
 note = {Objective: To detect the radiosensitivity of intratumour quiescent (Q) cells unlabelled with pimonidazole to accelerated carbon ion beams and the boron neutron capture reaction (BNCR).
Methods: EL4 tumour-bearing C57BL/J mice received 5-bromo-29-deoxyuridine (BrdU)
continuously to label all intratumour proliferating (P) cells. After the administration of pimonidazole, tumours were irradiated with c-rays, accelerated carbon ion beams or reactor neutron beams with the prior administration of a 10B-carrier. Responses of intratumour Q and total (P+Q) cell populations were assessed based on frequencies of micronucleation and apoptosis using immunofluorescence staining for BrdU. The response of pimonidazole-unlabelled tumour cells was assessed by means of apoptosis frequency using immunofluorescence staining for pimonidazole.
Results: Following c-ray irradiation, the pimonidazole-unlabelled tumour cell fraction showed significantly enhanced radiosensitivity compared with the whole tumour cell fraction, more remarkably in the Q than total cell populations. However, a significantly greater decrease in radiosensitivity in the pimonidazole-unlabelled cell fraction, evaluated using a delayed assay or a decrease in radiation dose rate, was more clearly observed among the Q than total cells. These changes in radiosensitivity were suppressed following carbon ion beam and neutron beam-only irradiaton. In the BNCR, the use of a 10B-carrier, especially L-para-boronophenylalanine-10B, enhanced the sensitivity of the pimonidazole-unlabelled cells more clearly in the Q than total cells.
Conclusion: The radiosensitivity of the pimonidazole-unlabelled cell fraction depends on the quality of radiation delivered and characteristics of the 10B-carrier used in the BNCR.},
 title = {Radiosensitivity of pimonidazole-unlabeled intratumor quiescent cell population to gamma-rays, accelerated carbon ion beams and boron neutron capture reaction},
 volume = {86},
 year = {2013}
}