Iy. Belyaev et al., RELATIONSHIP BETWEEN RADIATION-INDUCED ADAPTIVE RESPONSE IN HUMAN FIBROBLASTS AND CHANGES IN CHROMATIN CONFORMATION, Mutation research, 358(2), 1996, pp. 223-230
Chromatin conformation changes in the normal human fibroblasts VH-10 w
ere studied by the method of anomalous viscosity time dependence (AVTD
). Gamma-irradiation of cells in a dose range of 0.1-3 Gy caused an in
crease in maximal viscosity of cell lysates. Conversely, irradiation o
f cells with low doses of 0.5 or 2 cGy resulted in a decrease in the A
VTD peaks with a maximum effect approximately 40 min after irradiation
. The same exposure conditions were used to study a possible adaptive
effect of low doses, measured by changes in cell survival. A primary d
ose of 2 cGy caused significant modification of cell response to a cha
llenge dose. Approximately 20% protection to challenge doses of 0.5 Gy
(p < 0.003), 2 Gy (p < 0.02) and 2.5 Gy (p < 0.002) was observed. How
ever, the direction of this effect (adaptation or synergism) was found
to be dependent on a challenge dose. The combined effect of 2 cGy and
1 Gy was significantly synergistic, while no modification was observe
d for 1.5 Gy and 3 Gy. A partial correlation was found between the AVT
D changes and cell survival when the combined effect of a primary dose
of 2 cGy and challenge dose was examined. The dose of 2 cGy alone inc
reased survival by 16% (p < 0.0003). These results suggest that the lo
w-dose induced effects on survival may be related to chromatin reorgan
ization.