Yun-Shan Li

Urea, the most abundant component in urine, cross-reacts with a commercial 8-OH-dG ELISA kit and contributes to overestimation of urinary 8-OH-dG

Urinary 8-OH-dG is commonly analyzed as a marker of oxidative stress. For its analysis, ELISA and HPLC methods are generally used, although discrepancies in the data obtained by these methods have often been discussed. To clarify this problem, we fractionated human urine by reverse-phase HPLC and assayed each fraction by the ELISA method. In addition to the 8-OH-dG fraction, a positive reaction was observed in the first eluted fraction. The components in this fraction were examined by the ELISA. Urea was found to be the responsible component in this fraction. Urea is present in high concentrations in the urine of mice, rats, and humans, and its level is influenced by many factors. Therefore, certain improvements, such as a correction based on urea content or urease treatment, are required for the accurate analysis of urinary 8-OH-dG by the ELISA method. In addition, performance of the ELISA at 4 degrees C reduced the recognition of urea considerably and improved the 8-OH-dG analysis.

DNA methylation by dimethyl sulfoxide and methionine sulfoxide triggered by hydroxyl radical and implications for epigenetic modifications

In this Letter, we demonstrate the formation of m(5)dC from dC or in DNA by dimethylsulfoxide (DMSO) and methionine sulfoxide (MetO), under physiological conditions in the presence of the Fenton reagent in vitro. DMSO reportedly affects the cellular epigenetic profile, and enhances the metastatic potential of cultured epithelial cells. The methionine sulfoxide reductase (Msr) gene was suggested to be a metastatis suppressor gene, and the accumulation of MetO in proteins may induce metastatic cancer. Our findings are compatible with these biological data and support the hypothesis that chemical cytosine methylation via methyl radicals is one of the mechanisms of DNA hypermethylation during carcinogenesis. In addition to m(5)dC, the formation of 8-methyldeoxyguanosine (m(8)dG) was also detected in DNA under the same reaction conditions. The m(8)dG level in human DNA may be a useful indicator of DNA methylation by radical mechanisms.

Urinary 1-hydroxypyrene and 8-hydroxydeoxyguanosine Levels among Coke-oven Workers for 2 Consecutive Days

Urinary 1‐hydroxypyrene and 8‐hydroxydeoxyguanosine Levels among Coke‐oven Workers for 2 Consecutive Days: Thi‐To‐Uyen NGUYEN, et al. Department of Health Policy and Management, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan—

Assessment of Pulmonary Toxicity Induced by Inhaled Toner with External Additives

We investigated the harmful effects of exposure to a toner with external additives by a long-term inhalation study using rats, examining pulmonary inflammation, oxidative stress, and histopathological changes in the lung. Wistar rats were exposed to a well-dispersed toner (mean of MMAD: 2.1 μm) at three mass concentrations of 1, 4, and 16 mg/m3 for 22.5 months, and the rats were sacrificed after 6 months, 12 months, and 22.5 months of exposure. The low and medium concentrations did not induce statistically significant pulmonary inflammation, but the high concentration did, and, in addition, a histopathological examination showed fibrosis in the lung. Although lung tumor was observed in one sample of high exposure for 22.5 months, the cause was not statistically significant. On the other hand, a persistent increase in 8-OHdG was observed in the high exposure group, indicating that DNA damage by oxidative stress with persistent inflammation leads to the formation of tumorigenesis. The results of our studies show that toners with external additives lead to pulmonary inflammation, oxidative stress, and fibrosis only at lung burdens beyond overload. These data suggest that toners with external additives may have low toxicity in the lung.

Intensity-specific effect of physical activity on urinary levels of 8-hydroxydeoxyguanosine in middle-aged Japanese

Physical activity (PA) is recommended to both promote and maintain health and prevent cancer by improving the bodys DNA repair system, which is considered a mechanism of cancer prevention. However, associations between PA and urinary levels of 8‐hydroxydeoxyguanosine (8‐OH‐dG), which reflects DNA damage, are unclear. This cross‐sectional study included 2370 men and 4052 women aged 45–74 years enrolled between 2010 and 2012. Habitual PA was assessed by single‐axis accelerometer and urinary 8‐OH‐dG levels by automated HPLC. Multiple linear regression analysis was used to examine the relationship between log‐transformed urinary 8‐OH‐dG and total PA (TPA) and PA of moderate/vigorous intensity (MVPA; ≥3 metabolic equivalents), with adjustment for age, body mass index, energy intake, alcohol consumption, smoking status, daily coffee drinking, menopause status (in women), and TPA (for MVPA). On multivariate adjustment, urinary 8‐OH‐dG levels were inversely correlated with TPA (β = −0.020, P < 0.01) in women, and this correlation was not changed by PA intensity. Conversely, urinary 8‐OH‐dG levels were inversely correlated with MVPA (β = −0.022, P < 0.05) in men, although the correlation with TPA was non‐significant. This inverse correlation was clearer in current smokers than in never or former smokers, although the interaction between smoking status and MVPA on urinary 8‐OH‐dG levels was non‐significant. In conclusion, greater TPA in women and greater MVPA in men were correlated with reduction in urinary 8‐OH‐dG, suggesting sex‐specific effects of MVPA and TPA on protection from oxidative DNA damage. Increasing PA may mediate reduction in oxidative stress.

Free radical-mediated cytosine C-5 methylation triggers epigenetic changes during carcinogenesis

Abstract The methylation of the C-5 position of deoxycytidine (dC) in the promoter regions of tumor suppressor genes is often observed in cancer cells. We found that various environmental agents, as well as endogenous compounds such as methionine sulfoxide (MetO), generate methyl radicals and modify dC to form 5-methyl-dC in DNA in vitro. We confirmed that both DNA methylation and cancer incidence in the liver were increased by the administration of MetO to oxidatively stressed mice. In this review, we summarize previous reports on methyl radical generation in vitro and in vivo and DNA modifications by methyl radicals, including our discoveries, as well as our recent experimental evidence suggesting that free radical-mediated dC methylation triggers epigenetic changes.

Comparison of Blueberry (Vaccinium spp.) and Vitamin C via Antioxidative and Epigenetic Effects in Human

Background Chemopreventive effects and the underlying mechanisms of blueberry (Vaccinium spp.) are not clearly understood in human. We hypothesized blueberry would work via antioxidative and epigenetic modulation, which is similar to vitamin C. Methods We performed a pilot and non-inferiority study in healthy young women (n = 12), who consumed vitamin C (1 g/d) or 240 mL of blueberry juice (total polyphenols 300 mg and proanthocyanidin 76 mg/d) for 2 weeks. We analyzed 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) levels in their urine, and global and specific DNA methylation at the NAD(P)H quinone oxidoreductase 1 (NQO1), methylenetetrahydrofolate reductase (MTHFR), or DNA methyltransferase 1 (DNMT1) genes in their blood. Results Urinary 8-OHdG levels were reduced by blueberry consumption rather than by vitamin C. The methylation (%) of the MTHFR was significantly decreased in blueberry-consumers and the antioxidant-susceptible subgroup, whose urinary MDA levels were decreased by the intervention. We also found a positive correlation between changes of urinary 8-OHdG and of DNA methylation at the MTHFR or the DNMT1 (P < 0.05). However, the genetic polymorphism of the MTHFR (C677T in exon 4) did not affect any above markers. Conclusions Blueberry juice shows similar anti-oxidative or anti-premutagenic activity to vitamin C and the potential as a methylation inhibitor for the MTHFR and the DNMT1 in human.

Antioxidant properties of green tea aroma in mice

Green tea (‘Sencha’), made from the leaves of Camellia sinensis, is the most well-researched antioxidant beverage. The major source of its antioxidant activity is polyphenols, consisting mainly of catechins (flavan-3-ols). However, little is known about the physiological effects of green tea aroma, which lacks catechins. In the present study, we performed inhalation experiments with green tea aroma to evaluate its antioxidant activity in mice. As a result, the urinary 8-hydroxydeoxyguanosine levels were significantly decreased in comparison with those of the non-treated group, and the serum antioxidant capacity was significantly increased by the inhalation administration of green tea aroma. Furthermore, the increase in the urinary 8-hydroxydeoxyguanosine levels due to whole-body X-ray irradiation was significantly suppressed by the inhalation of green tea aroma. This is the first study to show the antioxidant activity of green tea aroma in vivo.

Biopersistence of NiO and TiO2 Nanoparticles Following Intratracheal Instillation and Inhalation

The hazards of various types of nanoparticles with high functionality have not been fully assessed. We investigated the usefulness of biopersistence as a hazard indicator of nanoparticles by performing inhalation and intratracheal instillation studies and comparing the biopersistence of two nanoparticles with different toxicities: NiO and TiO2 nanoparticles with high and low toxicity among nanoparticles, respectively. In the 4-week inhalation studies, the average exposure concentrations were 0.32 and 1.65 mg/m3 for NiO, and 0.50 and 1.84 mg/m3 for TiO2. In the instillation studies, 0.2 and 1.0 mg of NiO nanoparticles and 0.2, 0.36, and 1.0 mg of TiO2 were dispersed in 0.4 mL water and instilled to rats. After the exposure, the lung burden in each of five rats was determined by Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES) from 3 days to 3 months for inhalation studies and to 6 months for instillation studies. In both the inhalation and instillation studies, NiO nanoparticles persisted for longer in the lung compared with TiO2 nanoparticles, and the calculated biological half times (BHTs) of the NiO nanoparticles was longer than that of the TiO2 nanoparticles. Biopersistence also correlated with histopathological changes, inflammatory response, and other biomarkers in bronchoalveolar lavage fluid (BALF) after the exposure to nanoparticles. These results suggested that the biopersistence is a good indicator of the hazards of nanoparticles.

234 Urinary 8-hydroxydeoxyguanosine levels of emergency medical shift workers are higher than those of factory workers

Introduction Shiftwork is known as a risk factor of breast cancer and prostate cancer. In fact, the International Agency for Research on Cancer (IARC) classified shiftwork as Class 2A. One mechanism is that shiftwork increases cellular oxidative stress and results in DNA damage. Urinary 8-hydroxydeoxyguanosine (8-OHdG) is frequently analysed as an oxidative stress marker. However, there have been few studies investigating the association of shiftwork with urinary 8-OHdG levels. In this study, we investigated the association between shiftwork with oxidative stress and urinary 8-OHdG levels. Methods Urine samples from eight medical shift workers were collected before and after the night shift. The 8-OHdG levels were measured with a high-performance liquid chromatography (HPLC) system equipped with an electrochemical detector. Results The mean level of urinary 8-OHdG (µg/ng creatinine) in this study was 5.40±1.70, and was higher than that of factory workers in a past study. There were no significant differences in the urinary 8-OHdG levels before and after the night shift work. Conclusion These results suggest that shiftwork, strain, and chronic fatigue lead to oxidative stress and DNA damage. The urinary 8-OHdG level may be a useful biomarker, as an evaluating factor for chronic fatigue in regard to shiftwork.