Bulky DNA adducts in human sperm: relationship with fertility, semen quality, smoking, and environmental factors

The integrity of DNA of spermatogenic cells can be affected by endogenous and exogenous genotoxic factors. Resulting DNA damage in spermatozoa may significantly contribute to impaired fertility. Here, the 32P-postlabeling method was used to analyze the levels of bulky DNA adducts in sperm cells in a group of 179 males, either healthy donors or patients with an impaired fertility. When all donors were analyzed, the levels of bulky DNA adducts was 1.2-fold higher in smokers than in non-smokers, but the difference was not statistically significant (P=0.054). However, a statistically significant difference existed between current smokers and never smokers among the healthy individuals (1.7-fold increase, P=0.008). No correlation between alcohol or coffee consumption and sperm DNA adducts was found. The levels of DNA adducts in sperm seemed to be unaffected by environmental and occupational factors. On the other hand, groups of healthy persons and patients with male-factor infertility differed significantly with respect to the level of bulky DNA adducts (P=0.012). A significant negative correlation between DNA adducts and sperm concentration or sperm motility existed among patients with an impaired fertility (n=93; P<0.029, r(S)=-0.225). These results suggest that DNA adducts in sperm cells can be applied as potential biomarkers in studies of human infertility.

Radiation-induced DNA damage and its repair in lymphocytes of patients with head and neck cancer and healthy donors

BACKGROUND

DNA repair capacity may be an important factor in determining both individual susceptibility to cancer and the response to cancer therapy. The aim of this work was to compare DNA damage and the repair process in cells originating from healthy donors and cancer patients.

MATERIALS AND METHODS

Using the micronucleus and comet assays, we compared the induction of DNA damage and its repair in lymphocytes isolated from blood samples of 14 healthy donors and 24 patients with head and neck tumours. Gamma-rays at the dose of 2 or 4 Gy were used as the damaging factor. The micronucleus test was performed according to Fenech (1) and the comet assay according to Green et al. (2).

RESULTS AND CONCLUSION

Lymphocytes of both healthy donors and tumour patients showed great diversification in reaction to the same dose of gamma irradiation as well as differences in the kinetics of DNA repair. The patient group contained significantly more individuals whose lymphocytes were characterized by higher background DNA damage and higher damage inducibility. Blood cells of donors showing high damage inducibility also showed increased levels of micronuclei induced by ionizing radiation. Micronuclei induction did not correlate with a high level of unrepaired DNA damage.