%0 Journal Article
%T Is the Oxidative DNA Damage Level of Human Lymphocyte Correlated with the Antioxidant Capacity of Serum or the Base Excision Repair Activity of Lymphocyte?
%A Yi-Chih Tsai
%A Pei-Yi Li
%A Chung-Chu Chen
%A Yin-Chang Liu
%J Oxidative Medicine and Cellular Longevity
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/237583
%X A random screening of human blood samples from 24 individuals of nonsmoker was conducted to examine the correlation between the oxidative DNA damage level of lymphocytes and the antioxidant capacity of serum or the base excision repair (BER) activity of lymphocytes. The oxidative DNA damage level was measured with comet assay containing Fpg/Endo III cleavage, and the BER activity was estimated with a modified comet assay including nuclear extract of lymphocytes for enzymatic cleavage. Antioxidant capacity was determined with trolox equivalent antioxidant capacity assay. We found that though the endogenous DNA oxidation levels varied among the individuals, each individual level appeared to be steady for at least 1 month. Our results indicate that the oxidative DNA damage level is insignificantly or weakly correlated with antioxidant capacity or BER activity, respectively. However, lymphocytes from carriers of Helicobacter pylori (HP) or Hepatitis B virus (HBV) tend to give higher levels of oxidative DNA damage ( ). Though sera of this group of individuals show no particular tendency with reduced antioxidant capacity, the respective BER activities of lymphocytes are lower in average ( ). Thus, reduction of repair activity may be associated with the genotoxic effect of HP or HBV infection. 1. Introduction The endogenous level of DNA damage due to oxidative stress in human peripheral blood lymphocytes (PBL) has been extensively used as biomarkers in studying the genotoxic effects associated with diseases, microbial infection, ageing, or the exogenous agents [1¨C7]. However, the DNA damage levels presented in the previous studies were often collected at a single point time; it is unclear whether the damage level of concern is steady for a certain period of time, for example, a week or a month or longer. In this report, we showed that the endogenous level of DNA oxidation in lymphocytes from each individual was constant at least for 1 month (see the following). We measured the level of DNA oxidation in lymphocytes with a modified comet assay, which includes a step of enzymatic cleavage by bacterial Fpg/Endo III, recognizing oxidized purines and pyrimidines, respectively [8, 9]. We considered that such damage levels of PBL may be modulated by the antioxidant capacity of serum or the repair activity of lymphocytes. Like the measurement of DNA damage in PBL, serum or plasma antioxidant capacity has long been used as biomarker for various studies [10]. In contrast, the repair activity of PBL as biomarker just began to receive attention [11]. The repair activity
%U http://www.hindawi.com/journals/omcl/2013/237583/