title: Quantitative analyses of the induction of chromosome aberrations and sister-chromatid exchanges in human lymphocytes exposed to gamma-rays and mitomycin-C in combination.
abstract: Most chemicals are S-dependent and are potent inducers of SCE, but do not produce chromosome-type aberrations in the first metaphases after exposure. Ionizing radiation, which is an S-independent agent, produces chromosome-type aberrations, especially dicentrics and rings, but inefficiently produces chromatid-type aberrations. A series of experiments has been performed to investigate whether cytogenetic damage induced by ionizing radiation (gamma-rays) might be assessed separately from that induced by the alkylating chemical, mitomycin C (MMC), when human lymphocytes were exposed to these 2 agents in combination. Whole-blood cultures of human lymphocytes in G0 phase were exposed to gamma-rays and MMC in combination or separately. Cytogenetic analyses were done for both chromosome aberrations (CA), analyzed in cultures incubated for 56 h without BrdUrd, and sister-chromatid exchanges (SCEs) in cultures incubated for 72 h with BrdUrd. The frequency of chromosome-type aberrations (dicentrics and rings) increased with increasing doses of gamma-rays from 0.5 to 4.0 Gy. The dose-response relationships were the same with or without concomitant treatment with MMC (10(-6) M). Although the SCE frequency increased with increasing doses of MMC, the increase was nearly the same as when cells were treated with both MMC and gamma-rays (2 Gy). There was no interaction between MMC and gamma-rays concerning these 2 endpoints.
authors.affiliation: Department of Maternity and Child Health, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Iijima
authors.forename: K
authors.initials: K
authors.lastname: Morimoto
mesh_terms: D002478:Cells, Cultured; D002869:Chromosome Aberrations; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005720:Gamma Rays; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000528:radiation effects; D008297:Male; D016685:Mitomycin; D008937:Mitomycins / Q000633:toxicity*; D016192:Resting Phase, Cell Cycle; D012854:Sister Chromatid Exchange
chemical_list: D008937:Mitomycins; D016685:Mitomycin