The urinary 8-hydroxy-2'-deoxyguanosine levels have been widely used as a biomarker of oxidative stress. The purpose of this study is to investigate the diurnal and day-to-day variations of urinary 8-hydroxy-2'-deoxyguanosine levels. For the diurnal variation, the urine samples were collected at the time of awakening and every 2 h, from 10:00 to 22:00, from 6 healthy participants. For the day-to-day variation, the urine samples were collected at the time of awakening for 35 consecutive days, from 27 healthy participants. As a result, no differences were observed in the diurnal urinary 8-hydroxy-2'-deoxyguanosine levels, and each subject had a characteristic 8-hydroxy-2'-deoxyguanosine level. On the other hand, the daily 8-hydroxy-2'-deoxyguanosine values showed a certain range of variation reflecting lifestyle factors, such as stress status, exercise, sleep time, drinking and diet. In conclusion, urinary 8-hydroxy-2'-deoxyguanosine may be a useful biomarker to control and prevent oxidative stress-related diseases, if the certain range of day-to-day variations of urinary 8-hydroxy-2'-deoxyguanosine is known. Even with only one measurement per year, the baseline urinary 8-hydroxy-2'-deoxyguanosine level could be achieved in a few years by incorporating the 8-hydroxy-2'-deoxyguanosine measurement as part of an annual health check. As the number of subjects was limited, further studies are needed for practical applications.

Concerns have recently grown about the health effects of secondhand smoke exposure and heated tobacco products. The analysis of tobacco smoke biomarkers is critical to assess the health effects of tobacco smoke exposure. For this purpose, the simultaneous determinations of exposure markers and health effect markers would provide a better evaluation of smoke exposure. In this study, nicotine metabolites (nicotine, cotinine, trans-3'-hydroxycotinine) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in urine were analyzed as exposure markers. The DNA damage markers, 7-methylguanine and 8-hydroxy-2'deoxyguanosine, were simultaneously measured as health effect markers. The results revealed significant levels of urinary nicotine metabolites and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in the subjects exposed to secondhand smoke and heated tobacco products. In addition, the urinary levels of 7-methylguanine and 8-hydroxy-2'-deoxyguanosine tended to be high for secondhand smoke and heated tobacco products exposures, as compared to those of non-smokers. These biomarkers will be useful for evaluating tobacco smoke exposure.

Oxidative stress is a risk factor for lifestyle related diseases, such as cancer. Investigations of the factors that increase or decrease oxidative stress contribute to disease prevention. In the present study, we focused on the 8 hydroxyguanine (8 OHGua) in saliva, as a new oxidative stress biomarker. The relationship between lifestyles and salivary 8 OHGua levels in 541 Japanese subjects was analyzed. The salivary 8 OHGua levels were significantly elevated in older persons, as well as those who smoke, have hypertension, or excess visceral fat. By contrast, statistically significant lower levels of 8 OHGua were observed in persons who moderately exercised or recently drank green tea or coffee. The direct collec tion of saliva, without any special collecting device, was suitable for the 8 OHGua analysis. The present results suggest that oxida tive stress can be measured in a non invasive manner with easily collectable saliva, and the salivary 8 OHGua may be a useful bio marker for lifestyle related disease prevention.

Objective Oxidative stress is considered to cause lifestyle‐related diseases, including cancer. Urinary 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG) is widely analyzed as an oxidative stress marker. We extensively scrutinized the relationships between 8‐OHdG levels and lifestyle choices as carcinogenic factors. Methods In this study, we investigated health examination results and working conditions affecting urinary 8‐OHdG levels in 503 male workers. Results The urinary 8‐OHdG level was positively associated with high blood sugar and leanness in smokers. In addition, urinary 8‐OHdG tended to increase with organic solvent or hydrochloric acid exposure, as well as long working hours. On the other hand, the urinary 8‐OHdG level was negatively associated with high plasma LDL‐cholesterol levels in non‐smokers and anemia. Conclusion According to the results, anemia decreased the oxidative stress, regardless of smoking status, while leanness or high blood sugar increased the oxidative stress in smokers, and the presence of plasma cholesterol contributed to the lower oxidative stress in non‐smokers. Certain types of occupational exposure may cause oxidative stress. The measurement of urinary 8‐OHdG at annual health checks may be a useful biomarker for preventing lifestyle‐ and work‐related diseases.

IntroductionOxidative stress is a risk factor for life-style related diseases, including cancer. We recently reported that the oxidative stress marker 8-hydroxyguanine (8-OHGua) can be measured in saliva non-invasively. Understanding the diurnal pattern of salivary 8-OHGua levels is crucial for evaluating the oxidative stress. In this study, we analyzed the diurnal variation of salivary 8-OHGua levels.FindingsThe salivary 8-OHGua levels were relatively stable in the daytime (10:00–22:00). The daytime 8-OHGua levels seemed to represent the individual oxidative stress status. The average amount and the variation of the salivary 8-OHGua levels immediately after awakening were higher than those of the daytime levels.ConclusionsThe 8-OHGua levels in saliva exhibited diurnal variation. The levels were higher at the time of awakening. At this point, the daytime levels of salivary 8-OHGua may be appropriate for evaluating the individual oxidative stress status. Further study is needed for understanding and utilizing the 8-OHGua levels at the time of awakening.