K. Matsumoto et al., PERSISTENCE OF RADIATION-INDUCED TRANSLOCATIONS IN HUMAN PERIPHERAL-BLOOD DETERMINED BY CHROMOSOME PAINTING, Radiation research, 149(6), 1998, pp. 602-613
Citations number
44
Categorie Soggetti
Biology Miscellaneous","Radiology,Nuclear Medicine & Medical Imaging
We have investigated the persistence of translocations and other types
of chromosome damage with time using human peripheral blood acutely e
xposed in vitro to Cs-137 gamma rays at doses ranging from 0.5 to 4 Gy
, Freshly drawn blood from one donor was irradiated and metaphase chro
mosomes were prepared 2 to 7 days after exposure. Chromosomes 1, 2 and
4 were painted red-orange and chromosomes 3, 5 and 6 were painted gre
en by fluorescence in situ hybridization (FISH) using ''semi-directly'
' labeled whole-chromosome painting probes. This type of labeling comb
ines direct and indirect labeling and showed significant advantages ov
er both these other methods. All types of structural chromosome aberra
tions were classified by the Protocol for Aberration Identification an
d Nomenclature Terminology (PAINT) system. The yields of dicentric chr
omosomes, acentric fragments and ring chromosomes diminished with time
as expected. Translocations exhibited greater persistence but showed
a clear and statistically significant reduction in frequency at all do
ses. The mathematical model suggested that the translocation frequenci
es would reach a plateau of approximately 4, 15, 51, 106 and 179 trans
locations per 100 cell equivalents after irradiation with 0.5, 1, 2, 3
and 4 Gy, respectively. When translocations were classified by the co
nventional system, an analysis of the distribution of translocations a
nd dicentrics per cell indicated that both types of exchanges were Poi
sson-distributed 48 h postirradiation. However, cells bearing transloc
ations have a higher possibility of having dicentrics than cells witho
ut translocations, These findings suggest that dicentrics may contribu
te to a decline of translocation frequencies with time, and that some
translocations are not completely persistent. The results obtained her
e using human blood exposed in vitro may influence the use of transloc
ations as a retrospective biodosimeter of exposure to ionizing radiati
on in humans. (C) 1998 by Radiation Research Society.