Lower serum levels of beta-carotene in Lithuanian men are accompanied by higher urinary excretion of the oxidative DNA adduct, 8-hydroxydeoxyguanosine. The LiVicordia study

The relationship between plasma and urinary 8-hydroxy-2-deoxyguanosine biomarkers measured by liquid chromatography tandem mass spectrometry

Although 8-hydroxy-2-deoxyguanosine (8-OHdG) is a widely used promising biomarker of DNA damage, there are concerns about which tissues or body fluids should be sampled. The objective of this study is to evaluate the correlation of DNA oxidative damage biomarkers, 8-OHdG, between blood and urine and risk factors associated with 8OHdG. The study population was recruited from a baseline survey of a worksite lifestyle study including 92 office workers aged 23 to 60 years. A self-administered questionnaire was used to collect information on personal characteristics. The plasma and urinary 8-OHdG was measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). In linear regression, a positive relation was found (p < 0.01) between the log-transformed plasma and urinary 8-OHdG levels adjusted for gender, age, BMI, and smoking status. Our findings showed that age, gender and smoking were significantly associated with plasma 8-OHdG, but not with urinary 8-OHdG. Our results suggest that there is a positive relation between the biomarkers of plasma (steady state DNA damage) and urinary 8-OHdG (total DNA damage). However, the plasma 8-OHdG is more sensitive than urinary 8-OHdG to detect increased oxidative damages induced by risk factors.

Lung cancer biomarkers for the assessment of modified risk tobacco products: an oxidative stress perspective

Manufacturers have developed prototype cigarettes yielding reduced levels of some tobacco smoke toxicants, when tested using laboratory machine smoking under standardised conditions. For the scientific assessment of modified risk tobacco products, tests that offer objective, reproducible data, which can be obtained in a much shorter time than the requirements of conventional epidemiology are needed. In this review, we consider whether biomarkers of biological effect related to oxidative stress can be used in this role. Based on published data, urinary 8-oxo-7,8-dihydro-2-deoxyguanosine, thymidine glycol, F2-isoprostanes, serum dehydroascorbic acid to ascorbic acid ratio and carotenoid concentrations show promise, while 4-hydroxynonenal requires further qualification.

Antioxidants and cardiovascular disease: Still a topic of interest

Cardiovascular disease constitutes a major public health concern in industrialised nations. Over recent decades, a large body of evidence has accumulated indicating that free radicals play a critical role in cellular processes implicated in atherosclerosis. Herein, we present a mechanism of oxidative stress, focusing mainly on the development of an oxidised low density lipoprotein, and the results of a clinical trial of antioxidant therapy and epidemiological studies on the relationships between nutrient antioxidants, such as vitamin E, vitamin C, β-carotene, coenzyme Q, flavonoids and L-arginine, and coronary events. These studies indicated that a diet high in antioxidants is associated with a reduced risk of cardiovascular disease, but did not confirm a strong causality link. With regard to vitamin E, observational studies suggested that the daily use of at least 400 International Units of vitamin E is associated with beneficial effects on coronary events. However, it is apparently too early to define the clinical benefits of vitamin E for cardiovascular disease. From the results of several randomised interventional trials, it appears that no single antioxidant given to subjects at high doses has substantial benefits, and the question of whether nutrient antioxidants truly protect against cardiovascular disease remains open. This article provides an overview of the epidemiological and clinical studies related to antioxidants and cardiovascular disease.

Association between 8-oxo-7,8-dihydroguanine excretion and risk of lung cancer in a prospective study

Oxidative damage to guanine (8-oxoGua) is one of the most abundant lesions induced by oxidative stress and documented mutagenic. 8-Oxoguanine DNA glycosylase 1 (OGG1) removes 8-oxoGua from DNA by excision. The urinary excretion of 8-oxoGua is a biomarker of exposure, reflecting the rate of damage in the steady state. The aim of this study was to investigate urinary 8-oxoGua as a risk factor for lung cancer. In a nested case-cohort design we examined associations between urinary excretion of 8-oxoGua and risk of lung cancer as well as potential interaction with the OGG1 Ser326Cys polymorphism in a population-based cohort of 25,717 men and 27,972 women aged 50-64 years with 3-7 years follow-up. We included 260 cases with lung cancer and a subcohort of 263 individuals matched on sex, age, and smoking duration for comparison. Urine collected at entry was analysed for 8-oxoGua by HPLC with electrochemical detection. There was no significant effect of smoking or OGG1 genotype on the excretion of 8-oxoGua. Overall the incidence rate ratio (IRR) (95% confidence interval) of lung cancer was 1.06 (0.97-1.15) per doubling of 8-oxoGua excretion. The association between lung cancer risk and 8-oxoGua excretion was significant among men [IRR: 1.17 (1.03-1.31)], never-smokers [IRR: 9.94 (1.04-94.7)], and former smokers [IRR: 1.19 (1.07-1.33)]. There was no significant interaction with the OGG1 genotype, although the IRR was 1.14 (0.98-1.34) among subjects homozygous for Cys326. The association between urinary 8-oxoGua excretion and lung cancer risk among former and never-smokers suggests that oxidative stress with damage to DNA is important in this group.

Vascular cell adhesion molecule-1 expression and signaling during disease: regulation by reactive oxygen species and antioxidants

The endothelium is immunoregulatory in that inhibiting the function of vascular adhesion molecules blocks leukocyte recruitment and thus tissue inflammation. The function of endothelial cells during leukocyte recruitment is regulated by reactive oxygen species (ROS) and antioxidants. In inflammatory sites and lymph nodes, the endothelium is stimulated to express adhesion molecules that mediate leukocyte binding. Upon leukocyte binding, these adhesion molecules activate endothelial cell signal transduction that then alters endothelial cell shape for the opening of passageways through which leukocytes can migrate. If the stimulation of this opening is blocked, inflammation is blocked. In this review, we focus on the endothelial cell adhesion molecule, vascular cell adhesion molecule-1 (VCAM-1). Expression of VCAM-1 is induced on endothelial cells during inflammatory diseases by several mediators, including ROS. Then, VCAM-1 on the endothelium functions as both a scaffold for leukocyte migration and a trigger of endothelial signaling through NADPH oxidase-generated ROS. These ROS induce signals for the opening of intercellular passageways through which leukocytes migrate. In several inflammatory diseases, inflammation is blocked by inhibition of leukocyte binding to VCAM-1 or by inhibition of VCAM-1 signal transduction. VCAM-1 signal transduction and VCAM-1-dependent inflammation are blocked by antioxidants. Thus, VCAM-1 signaling is a target for intervention by pharmacological agents and by antioxidants during inflammatory diseases. This review discusses ROS and antioxidant functions during activation of VCAM-1 expression and VCAM-1 signaling in inflammatory diseases.

DNA damage, a biomarker of carcinogenesis: its measurement and modulation by diet and environment

Free radicals and other reactive oxygen or nitrogen species are constantly generated in vivo and can cause oxidative damage to DNA. This damage has been implicated to be important in many diseases, including cancer. The assessment of damage in various biological matrices, such as tissues, cells, and urine, is vital to understanding this role and subsequently devising intervention strategies. During the last 20 years, many analytical techniques have been developed to monitor oxidative DNA base damage. High-performance liquid chromatography-electrochemical detection and gas chromatography-mass spectrometry are the two pioneering contributions to the field. Currently, the arsenal of methods available include the promising high-performance liquid chromatography-tandem mass spectrometry technique, capillary electrophoresis, 32P-postlabeling, antibody-base immunoassays, and assays involving the use of DNA repair glycosylases such as the comet assay. The objective of this review is to discuss the biological significance of oxidative DNA damage, evaluate the effectiveness of several techniques for measurement of oxidative DNA damage in various biological samples and review current research on factors (dietary and non-dietary) that influence DNA oxidative damage using these techniques.

Oxidative and nitrosative stress markers in bus drivers

Exposure to ambient air pollution is associated with many diseases. Oxidative and nitrosative stress are believed to be two of the major sources of particulate matter (PM)-mediated adverse health effects. PM in ambient air arises from industry, local heating, and vehicle emissions and poses a serious problem mainly in large cities. In the present study we analyzed the level of oxidative and nitrosative stress among 50 bus drivers from Prague, Czech Republic, and 50 matching controls. We assessed simultaneously the levels of 15-F(2t)-isoprostane (15-F(2t)-IsoP) and 8-oxodeoxyguanosine (8-oxodG) in urine and protein carbonyl groups and 3-nitrotyrosine (NT) in blood plasma. For the analysis of all four markers we used ELISA techniques. We observed significantly increased levels of oxidative and nitrosative stress markers in bus drivers. The median levels (min, max) of individual markers in bus drivers versus controls were as follows: 8-oxodG: 7.79 (2.64-12.34)nmol/mmol versus 6.12 (0.70-11.38)nmol/mmol creatinine (p<0.01); 15-F(2t)-IsoP: 0.81 (0.38-1.55)nmol/mmol versus 0.68 (0.39-1.79)nmol/mmol creatinine (p<0.01); carbonyl levels: 14.1 (11.8-19.0)nmol/ml versus 12.9 (9.8-16.6)nmol/ml plasma (p<0.001); NT: 694 (471-3228)nmol/l versus 537 (268-13833)nmol/l plasma (p<0.001). 15-F(2t)-IsoP levels correlated with vitamin E (R=0.23, p<0.05), vitamin C (R=-0.33, p<0.01) and cotinine (R=0.47, p<0.001) levels. Vitamin E levels also positively correlated with 8-oxodG (R=0.27, p=0.01) and protein carbonyl levels (R=0.32, p<0.001). Both oxidative and nitrosative stress markers positively correlated with PM2.5 and PM10 exposure. In conclusion, our study indicates that exposure to PM2.5 and PM10 results in increased oxidative and nitrosative stress.

Evaluation of Urinary 8-Hydroxydeoxyguanine inHealthy Japanese People

The urinary concentration of 8-hydroxydeoxyguanine (8-OHdG), which is a biomarker of oxidative DNA damage, was measured in 248 healthy Japanese, and its correlations with life style, urinary metal elements, serum antioxidants, and other plasma or serum factors were investigated. The mean urinary concentration of 8-OHdG was 15.2+/-5.71 ng/mg creatinine. Mean urinary 8-OHdG was not significantly different in terms of age (<45, >or=45), gender, smoking (no, <20, >or=20), and alcohol consumption (no, occasionally, sometimes and usually). Moreover, multiple regression analysis showed a significant association between urinary 8-OHdG and urinary arsenic (As) or chromium (Cr), and a tendency for association between the former and aluminum (Al) and nickel (Ni). Age, gender and plasma or serum factors including antioxidants, lipid peroxide, HbA1c, BUN, and iron did not show such an association. The present study suggests that natural exposure to toxic metal elements such as As, Cr, and Ni may influence oxidative DNA damage in healthy people under usual environmental management. Therefore, the measurement of urinary metals such as As, Ni and Cr is prerequisite for the study of the relationship between urinary 8-OHdG and other variable factors.

Prospective study of 8-oxo-7,8-dihydro-2'-deoxyguanosine excretion and the risk of lung cancer

Oxidative damage to DNA may be important in carcinogenesis and a possible risk factor for lung cancer. The urinary excretion of products of damaged nucleotides in cellular pools or in DNA may be important biomarkers of exposure to relevant carcinogens reflecting the rate of damage in steady state and may predict cancer risk. Oxidation of guanine in DNA or the nucleotide pool may give rise to 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) for urinary excretion. Oxoguanine glycosylase (OGG1) is the base excision enzyme repairing 8-oxodG in DNA by release of 8-oxoguanine. In a nested case-cohort design we examined associations between urinary excretion of 8-oxodG and risk of lung cancer as well as potential interaction with the OGG1 Ser326Cys polymorphism in a population-based cohort of 25 717 men and 27 972 women aged 50-64 years with 3-7 years follow-up. We included 260 cases with lung cancer and a sub-cohort of 263 individuals matched on sex, age and smoking duration for comparison. Urine collected at entry was analysed for 8-oxodG by HPLC with electrochemical detection. The excretion of 8-oxodG was higher in current smokers, whereas OGG1 genotype had no effect. Overall the incidence rate ratio (IRR) (95% confidence interval) of lung cancer was 0.99 (0.80-1.22) per doubling of 8-oxodG excretion and there was no interaction with OGG1 genotype. However, among never-smokers (eight cases and eight sub-cohort members) the IRR was 11.8 (1.21-115) per doubling of 8-oxodG excretion. The association between 8-oxodG excretion and lung cancer risk among never-smokers suggests that oxidative damage to DNA nucleotides is important in this group.

Determination of DMF modified DNA base N4-methylcarbamoylcytosine in human urine using off-line sample clean-up, two-dimensional LC and ESI-MS/MS detection

A sensitive internal standard method for the analysis of a DNA-adduct of N,N-dimethylformamide (N4-methylcarbamoylcytosine, NMC-C) in human urine has been developed. A sample pre-treatment involving an acidic hydrolysis is followed by the sample clean-up performed with solid-phase extraction (SPE) technique using a cation-exchange resin. A two-dimensional liquid chromatography is used to separate the target analyte from the matrix using first a C18 reversed phase column with incorporated hydrophilic moieties and then a C8 bonded reversed phase column for the final separation. Quantification is carried out by positive electrospray ionisation and mass spectrometry detection of the transitions from molecule ions to product ions (169-->112 and 172-->115) for the analyte and the labelled internal standard, respectively. The detection limit in urine reaches down to 8 ng/L (48 pmol/L). In the general population NMC-C could not be detected. In 10 out of 32 urine samples of occupationally to DMF exposed subjects NMC-C could be detected. The concentrations ranged up to 172 ng/L (1023 pmol/L) with a 95th percentile of 121 ng/L (720 pmol/L).

Exposure to traffic exhausts and oxidative DNA damage

AIMS

To assess the relations between exposure to traffic exhausts and indicators of oxidative DNA damage among highway toll station workers.

METHODS

Cross-sectional study of 47 female highway toll station workers exposed to traffic exhausts and 27 female office workers as a reference group. Exposure assessment was based on average and cumulative traffic density and a biomarker of exposure, urinary 1-hydroxypyrene-glucuronide (1-OHPG). Urinary 8-hydroxydeoxyguanosine (8-OHdG) was used as a biomarker of oxidative DNA damage. Plasma nitric oxide (NO) was measured as an indicator of oxidative stress related to traffic exhaust exposure.

RESULTS

The mean concentration of urinary 8-OHdG was substantially higher among the exposed non-smokers (13.6 microg/g creatinine) compared with the reference non-smokers (7.3 microg/g creatinine; difference 6.3, 95% CI 3.0 to 9.6). The mean concentration of NO among the exposed (48.0 micromol/l) was also higher compared with the reference non-smokers (37.6 micromol/l; difference 10.4, 95% CI -0.4 to 21.2). In linear regression adjusting for confounding, a change in log(8-OHdG) was statistically significantly related to a unit change in log(1-OHPG) (beta = 0.372, 95% CI 0.081 to 0.663).

CONCLUSIONS

Results indicate that exposure to traffic exhausts increases oxidative DNA damage. Urinary 8-OHdG is a promising biomarker of traffic exhaust induced oxidative stress.

Biological Relevance of Adduct Detection to the Chemoprevention of Cancer

Adducts arise from the chemical modification of bases in DNA or amino acids in proteins by toxic chemicals. Many chemicals known to be carcinogenic in humans have been shown to form adducts or to cause oxidative damage to genomic DNA in model systems. Biomarkers of carcinogenesis reflect biological events that take place between exposure to external or endogenous carcinogens and the subsequent development of cancer. Therapeutic intervention for the purpose of cancer chemoprevention may modify these biomarkers. In this article, the potential efficacy of DNA adducts as biomarkers of carcinogenesis and chemoprevention is discussed using criteria defined for phases of biomarker development. The sensitivity of adduct detection in histologically normal tissue offers opportunities for the early detection of carcinogenesis. Extensive evidence for aflatoxin B(1) adducts as biomarkers of risk and progression of hepatic carcinogenesis and for oxidative DNA adducts as biomarkers of the development of prostate carcinogenesis is reviewed together with the clinical trials measuring these adducts as biomarkers of the efficacy of chemoprevention. Favorable modification of oxidative DNA adducts by dietary intervention and chemoprevention has been demonstrated in preclinical and clinical studies. Protein adducts and DNA adducts in blood constituents or urine may act as useful surrogates for the target organ. Additional information regarding reliability, reproducibility, specificity, and confounding variables are required at the clinical level to validate adducts as suitable biomarkers of chemoprevention. "We do not administer antihypertensive drugs to patients in clinical trials without checking their blood pressure, so why should we give antioxidants without checking that they have decreased oxidant status.

Gamma-tocopherol--an underestimated vitamin?

The main research activities of the last decades on tocopherols were mainly focused on alpha-tocopherol, in particular when considering the biological activities. However, recent studies have increased the knowledge on gamma-tocopherol, which is the major form of vitamin E in the diet in the USA, but not in Europe. gamma-Tocopherol provides different antioxidant activities in food and in-vitro studies and showed higher activity in trapping lipophilic electrophiles and reactive nitrogen and oxygen species. The lower plasma levels of gamma- compared to alpha-tocopherol might be discussed in the light of different bioavailability, but also in a potential transformation from gamma- into alpha-tocopherol. From the metabolism end product, only that of gamma-tocopherol (2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman), but not that of alpha-tocopherol, was identified to provide natriuretic activity. Studies also indicate that only the gamma-tocopherol plasma level served as biomarker for cancer and cardiovascular risk. Therefore, this paper provides a comprehensive review on gamma-tocopherol with emphasis on its chemistry, biosynthesis, occurrence in food, different intake linking to different plasma levels in USA and Europe, absorption and metabolism, biological activities, and possible role in human health.