Study On Effects Of Ionizing Radiation On Health

Objective: The dose-, dose rate- and time-effects of adaptive response of apoptosis and cell cycle progression induced by low dose radiation were observed in vivo and in vitro.Methods: Kunming mice or lyphoma EL-4 cells were irradiated with inductive doses (doses of D1 were 25, 50, 100 and 200 mGy, dose rate was 12.5 mGy/min; dose of D1 was 75 mGy, dose rates were 6.25, 12.5, 25, 50, 100 and 200 mGy/min) and challenging doses (doses of D2 were 0.5, 1.0, 1.5, 2.0 and 3.0 Gy, dose rate was 287 mGy/min), the intervals between D1 and D2 were 3, 6, 12, 24, 48 and 60 h. The apoptosis, cell cycle progression and the expressions of its associated gene protein p53, Bcl-2 and Bax were measured with flow cytometer and the DNA fragmentation was measured with fluorospectrophotometry.Results: When the doses of D1 were 25– 100 mGy and the dose rate was 12.5 mGy/min (the interval between D1 and D2 was 6 h) , or the dose of D1 was 75 mGy and the dose rates were 6.25– 50 mGy/min (the intervals between D1 and D2 were 3, 6 and 24 h), and the doses of D2 were 0.5– 3.0 Gy, the percentages of apoptotic cells and G0/G1 or G2 + M phase cells increased significantly in the D2 groups as compared with those in the sham-irradiaton...