Reduced oxidative DNA damage by vegetable juice intake: a controlled trial

Reference ranges of oxidative stress biomarkers selected for non-invasive biological surveillance of nanotechnology workers: Study protocol and meta-analysis results for 8-OHdG in exhaled breath condensate

In the field of engineered nanomaterials (ENMs) and other airborne particulate exposure biomonitoring, circulating oxidative stress biomarkers appear promising. These biomarkers could be monitored in different biological matrices. Exhaled breath condensate (EBC) enables their measurements in the respiratory tract, without affecting airway function or creating inflammation. The 8-hydroxy-2-deoxyguanosine (8-OHdG) was found increased in the EBC of ENM-exposed workers. Our objectives were to assess the reference range of 8-OHdG in the EBC and to identify determinants of its inter- and intra-individual variability. The meta-analysis was stratified by analytical method (chemical versus immunochemical analysis) and resulted in a between-study variability over 99 % of the total variability. The between-study variability completely dominated the within-studies variability. By using a mixed model with study ID as a random effect rather than a meta-regression, only smoking was evidenced as a potential determinant of 8-OHdG inter-individual variability, and only when immunochemical analysis was used. To our knowledge, this is the first meta-analysis aimed at estimating reference values for 8-OHdG in the EBC. The estimated values should be considered preliminary, as they are based on a limited number of studies, mostly of moderate to low quality of evidence. Further research is necessary to standardize EBC sampling, storage and analytical methods. Such a standardization would enable a more accurate estimation of the reference ranges of the 8-OHdG and potentially other biomarkers measurable in the EBC, which are essential for a meaningful interpretation of the biomonitoring results.

DNA catabolites in triathletes: effects of supplementation with an aronia-citrus juice (polyphenols-rich juice)

In this study we analyzed whether our aronia-citrus juice (ACJ, the composition is based on a mixture of 95% citrus juice with 5% of Aronia melanocarpa juice), rich in polyphenols, and physical exercise had an effect on seven catabolites of DNA identified in plasma and on a urine isoprostane (8-iso-PGF2α). Sixteen elite triathletes on a controlled diet for triathlon training (45 days) were used in this clinical trial. Our results show a decrease in the 8-hydroxy-2'-deoxyguanosine concentration due to chronic physical exercise. The ACJ intake and physical exercise maintained the guanosine-3',5'-cyclic monophosphate plasmatic concentrations and decreased the concentration of 8-hydroxyguanine as well as urinary values of 8-iso-PGF2α. Finally, we observed a significant increase in the 8-nitroguanosine levels in triathletes after ACJ intake, compared to the placebo stage. It is concluded that the combination of the intake of ACJ, rich in polyphenolic compounds, with adequate training was able to influence the plasmatic and urinary values of oxidative stress biomarkers. This suggests a positive effect on the oxidative damage and potential associations with DNA repair mechanisms.

Antioxidant vitamins and cancer risk: is oxidative damage to DNA a relevant biomarker?

Oxidative damage to DNA is regarded as an important step in carcinogenesis. These lesions may arise as a consequence of exposure to xenobiotics, but are also generated as a consequence of endogenous generation of oxidizing compounds. Measurements of oxidative damage to guanines, such as 8-oxo-7, 8-dihydroguanine (8-oxodG) are increasingly being regarded as reliable biomarkers of oxidative stress and they may have a predictive value of cancer risk, although this needs to be established independently in several cohort studies. A survey of intervention studies of the ingestion of antioxidant-containing foods or tablets of antioxidants indicate that about one-third of the studies reported a protective effect in terms of lower levels of oxidative damage to DNA in white blood cells or decreased urinary excretion of 8-oxodG. Although firm conclusions cannot be reached, there appears to be links between ingestion of antioxidants, oxidative damage to DNA, and risk of cancer.

Calorie Restricted Diet and Urinary Pentosidine in Patients with Rheumatoid Arthritis

Low-energy diets and fasting have suppressive effects on rheumatoid arthritis. It was reported recently that urine levels of pentosidine (i.e., an advanced glycation end product formed by glycosylation) is associated with the activity of rheumatoid arthritis. We conducted a regimen of caloric restriction combined with fasting in patients with rheumatoid arthritis, and then evaluated urinary pentosidine levels. Ten patients with rheumatoid arthritis underwent a 54-day caloric restriction program. Urinary pentosidine levels were measured and the Lansbury Index were determined by examining the clinical features, blood biochemistry and the inflammation activity of rheumatoid arthritis on days 0, 25 and 54. On day 0, the mean urinary pentosidine level of patients with rheumatoid arthritis was significantly higher than that of the control subjects. On day 54, the mean body weight had reduced due to caloric restriction. The mean values of the erythrocyte sedimentation rate and the Lansbury Index of patients both significantly decreased during the study. In addition, although the urinary pentosidine levels showed no significant difference between day 0 and 25, it was significantly decreased at the end of the study (day 54). The study showed that under a low energy diet a reduction of disease activity in rheumatoid arthritis was accompanied with a reduction of the urinary pentosidine.