@article{oai:repo.qst.go.jp:00043454,
 author = {Okada, Maki and Saitou, Shiori and Okayasu, Ryuichi and 岡田 真希 and 斎藤 志織 and 岡安 隆一},
 journal = {Genetic Toxicology and Environmental Mutagenesis : A Section of Mutation Research},
 month = {},
 note = {We have measured rejoining kinetics of chromosome breaks using a modified cell fusion-based premature chromosome condensation (PCC) technique in confluent cultures of normal human fibroblasts irradiated at low doses of X-rays. In order to enhance the sensitivity of the fusion-based PCC assay, we added a DNA double strand break (DSB) repair inhibitor wortmannin during the incubation period for PCC/fusion process resulting in a significantly higher yield of G1-type chromosome breaks. The initial number of chromosome breaks (without repair) gave a linear dose response with about 10 breaks per cell per Gy which is about two times higher than the value with the conventional G1-type PCC method. The chromosome rejoining kinetics at 0.5 and 2.0 Gy X-rays reveal a bi-phasic curve with both a fast and a slow component. The fast component (0-30min) is nearly identical for both doses, but the slow component for 2 Gy kinetics is much slower than that for 0.5 Gy, indicating that the process occurring during this period may be crucial for the ultimate fate of irradiated cells. The chromosome rejoining kinetics obtained here is similar to that of other methods of detecting DNA DSB repair such as the H2AX assay. Our chromosome repair assay is useful for evaluating the accuracy of other assays measuring DNA DSB repair at doses equal or less than 0.5 Gy of ionizing radiation.},
 pages = {11--17},
 title = {Facilitated detection of chromosome break and repair at low levels of ionizing radiation by addition of wortmannin to G1-type PCC fusion incubation},
 volume = {562},
 year = {2004}
}