Hydrogen peroxide and radiation induced DNA damage investigated by the ''comet assay''

Human lymphocytes were irradiated by X-rays and fast neutrons or treated with hydrogen peroxide, and the degree of DNA damage was assessed using the single cell gel electrophoresis (SCGE) assay. Total percent of damaged cells after the treatment with hydrogen peroxide depends linearly on its concentration in the concentrations range 10-80 μM. Percentage of the cells with a high degree of DNA damage shows linear-quadratic concentration effect dependence. The data from X-rays irradiated lymphocytes present linear-quadratic dose response relationship for the cells with DNA damage over a dose of 0 to 0.4 Gy, and saturation of damage above it. Percentage of cells with the high degree of DNA damage shows linear-quadratic dose dependence in the whole X-rays dose range under the study. The data for lymphocytes irradiated with various doses of fast neutrons were processed in two different ways of lysis and electrophoresis. Alkaline and neutral conditions for lysis and electrophoresis were applied to distinguish between single and double strand DNA breaks, respectively. In both procedures the percentage of cells with high and total type of DNA damage revealed linear dose effect dependence. Comparison between DNA damage investigated by the ''Comet assay'' and chromosomal damage induced in human lymphocytes by radiation is also discussed. (author). 12 refs, 5 figs, 2 tabs