High- and low-LET induced chromosome damage in human lymphocytes: a time-course of aberrations in metaphase and interphase.
OBJECTIVE
To investigate how cell-cycle delays in human peripheral lymphocytes affect the expression of complex chromosome damage in metaphase following high- and low-LET radiation exposure.


METHODS
Whole blood was irradiated in vitro with a low and a high dose of 1 GeV u(-1) iron particles, 400MeV u(-1) neon particles or y-rays. Lymphocytes were cultured and metaphase cells were collected at different time points after 48-84h in culture. Interphase chromosomes were prematurely condensed using calyculin-A, either 48 or 72 h after exposure to iron particles or gamma-rays. Cells in first division were analysed using a combination of FISH whole-chromosome painting and DAPI/ Hoechst 33258 harlequin staining.


RESULTS
There was a delay in expression of chromosome damage in metaphase that was LET- and dose-dependant. This delay was mostly related to the late emergence of complex-type damage into metaphase. Yields of damage in PCC collected 48 h after irradiation with iron particles were similar to values obtained from cells undergoing mitosis after prolonged incubation.


CONCLUSIONS
The yield of high-LET radiation-induced complex chromosome damage could be underestimated when analysing metaphase cells collected at one time point after irradiation. Chemically induced PCC is a more accurate technique since problems with complicated cell-cycle delays are avoided.
NASA Lyndon B. Johnson Space Center, Radiation Biophysics Laboratory, Houston, TX 77058, USA. kerry.a.georgel@jsc.nasa.gov
K
K
George
H
H
Wu
V
V
Willingham
Y
Y
Furusawa
T
T
Kawata
F A
FA
Cucinotta
D006690:Bisbenzimidazole / Q000494:pharmacology; D002478:Cells, Cultured; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes; D005720:Gamma Rays; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007399:Interphase / Q000528:radiation effects*; D007501:Iron / Q000378:metabolism; D008214:Lymphocytes / Q000528:radiation effects*; D008297:Male; D008387:Marine Toxins; D008677:Metaphase / Q000528:radiation effects*; D009356:Neon / Q000378:metabolism; D010080:Oxazoles / Q000494:pharmacology; D013997:Time Factors
D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D008387:Marine Toxins; D010080:Oxazoles; D009356:Neon; C059041:calyculin A; D007501:Iron; D006690:Bisbenzimidazole