title: Proliferative kinetics and chromosome damage in trisomy 21 lymphocyte cultures exposed to gamma-rays and bleomycin.
abstract: Lymphocytes from patients with Down's syndrome (trisomy 21) have been investigated for cell cycle kinetics, cell proliferation delays, and chromosomal aberrations after exposure to gamma-rays or bleomycin. Analysis by sister chromatid differential staining revealed that trisomy 21 lymphocytes started cell cycling about 5 hr earlier than did normal diploid lymphocytes after phytohemagglutinin stimulation as a whole, but that cycling trisomic and normal cells had the same mean cell cycle times. When exposed to gamma-rays or bleomycin in G0, trisomy 21 lymphocytes showed a 30% or, on average, 50% longer duration of cell turnover times, respectively, than normal cells; only bleomycin-treated trisomic cells had a biphasic dose-response. Frequencies of dicentrics and rings in first-division cells after gamma-ray or bleomycin exposure were twice as high in trisomic cells as in normal cells. The frequency of aberrations decreased by 50% (gamma-ray-exposed) or 65 to 85% (bleomycin-treated) through successive divisions; trisomic cells showed a more marked decline in aberration yields compared to normal cells after bleomycin treatment. These data support the idea that circulating lymphocytes in trisomy 21 patients have a shorter average life span or a younger average age.
mesh_terms: D001761:Bleomycin / Q000633:toxicity*; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002877:Chromosomes, Human / Q000187:drug effects / Q000528:radiation effects*; D004261:DNA Replication / Q000187:drug effects / Q000528:radiation effects; D004314:Down Syndrome / Q000235:genetics*; D005720:Gamma Rays; D006801:Humans; D008214:Lymphocytes / Q000502:physiology*; D008940:Mitotic Index / Q000187:drug effects / Q000528:radiation effects
chemical_list: D001761:Bleomycin