title: Sister chromatid exchange in normal adults long after thymus irradiation.
abstract: Chromosomal breaks are seen in the peripheral blood lymphocytes of irradiated patients long after the original exposure. This is confirmed in our present investigation. We found 141 (20%) chromosomal breaks in 707 metaphases from 18 thymus-irradiated patients and only 26 (6.3%) in 410 metaphases from six of their normal siblings. Sister chromatid exchange (SCE) has been used to test the mutagen-carcinogen agents. However, radiation, a well-known mutagen-carcinogen agent, has no effect upon SCE. This suggests that the SCE and chromosomal breakage mechanisms may be quite different; study of them may help us to understand chromosomal breakage and healing.
mesh_terms: D000328:Adult; D002875:Chromosomes / Q000528:radiation effects; D003434:Crossing Over, Genetic / Q000528:radiation effects*; D006801:Humans; D007223:Infant; D008214:Lymphocytes / Q000648:ultrastructure; D011878:Radiotherapy / Q000009:adverse effects*; D012854:Sister Chromatid Exchange / Q000528:radiation effects*; D013950:Thymus Gland / Q000528:radiation effects*; D013997:Time Factors