摘要：The time-course of Fe-ion (200 MeV/u, 440 keV/ μm) and X-ray induced chromosomal damage was investigated in human lymphocytes. After cells were exposed in G 0 and stimulated to grow, aberrations were measured in first-cycle metaphases harvested 48, 60 and 72h post-irradiation. Additionally, lesions were analysed in G 2 and mitotic (M) cells collected at 48h using calyculin A-induced premature chromosome condensation (PCC). Following X-irradiation, similar aberration yields were found in all of the samples scored. In contrast, after Fe-ion exposure a drastic increase in the aberration frequency with sampling time was observed, i.e. cells arriving late at the first mitosis carried more aberrations than those arriving at earlier times. The PCC data indicate that the delayed entry of heavily damaged cells into mitosis observed after Fe-ion irradiation resulted from a prolonged arrest in G 2 . Altogether these experiments provide further evidence that in the case of high-LET exposure cell-cycle delays of severely damaged cells have to be taken into account for any meaningful quantification of chromosomal damage and, consequently, for an accurate estimate of the RBE.
关键词：Human lymphocytes; Heavy ions; Time-course of aberrations; Calyculin A; Apoptosis
