Assessment of exposure and DNA damage from second-hand smoke using potential biomarker in urine: cigarettes and heated tobacco products.

Second-hand smoke exposure is an established cause of several adverse health effects. Tobacco smoke exposure in the environment has been improved by the WHO Framework Convention on Tobacco Control. However, concerns have been raised regarding the health effects of heated tobacco products. Analysis of tobacco smoke biomarkers is critical for assessing the health effects of second-hand tobacco smoke exposure. In this study, nicotine metabolites (nicotine, cotinine, trans-3'-hydroxycotinine) and carcinogenic 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol were analysed in the urine of non-smokers with or without passive exposure to cigarettes and heated tobacco products. In addition, 7-methylguanine and 8-hydroxy-2'-deoxyguanosine were simultaneously measured as DNA damage markers. The results revealed higher levels of urinary nicotine metabolites and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in participants exposed to second-hand tobacco smoke (both cigarettes and heated tobacco products) at home. In addition, the urinary levels of 7-methylguanine and 8-hydroxy-2'-deoxyguanosine tended to be higher in the second-hand tobacco smoke-exposed group. The urinary levels of nicotine metabolites and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol were high in workplaces with no protection against passive smoking. These biomarkers will be useful for evaluating passive exposure to tobacco products.

Urinary biomarkers for secondhand smoke and heated tobacco products exposure.

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.

Health examination results and work environment factors affecting urinary 8-hydroxy-2'-deoxyguanosine levels.

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.

Diurnal and day-to-day variation of urinary oxidative stress marker 8-hydroxy-2'-deoxyguanosine.

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.

Effects of smoking cessation on biological monitoring markers in urine.

INTRODUCTION: Urinary nicotine and cotinine levels are often measured as biomarkers for tobacco smoke exposure. However, these biomarkers are not appropriate to evaluate the effects of quitting smoking for several days, because of their short half-lives. In this study, we focused on the changes in the urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels of 55 patients in a smoking cessation program, because of the long half-life. At the same time, urinary 7-methylguanine (m7Gua) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), as DNA damage markers of cigarette smoking, were also measured. RESULTS: In the subjects who completed the quit-smoking program (18 subjects out of 55), the urinary nicotine and cotinine levels decreased to 1.7 and 0.2% at 8 weeks after the first visit to the clinic. By contrast, the NNAL levels decreased to 12.3% at 8 weeks after quitting smoking. During the same period, the urinary m7Gua levels significantly decreased, from 27.32 µg/mg creatinine to 14.17 µg/mg creatinine by the elimination of subjects who showed increased levels of NNAL during the smoking cessation program. The 8-OHdG levels were also reduced within the same period, but were not significantly different. From the all data analysis, the urinary levels of cotinine and NNAL positively correlated with the level of m7Gua. CONCLUSIONS: NNAL may be an appropriate exposure marker for evaluating the smoking status of patients in a smoking cessation program. The urinary cotinine and NNAL levels positively correlated with the m7Gua levels.

Oxidative DNA damage in the rat lung induced by intratracheal instillation and inhalation of nanoparticles.

Nanoparticles are widely used as useful industrial materials. Therefore, their possible adverse health effects must be appraised. We assessed and compared the oxidative DNA damage caused by four different nanoparticles (TiO2, NiO, ZnO and CeO2). The effects of the administration methods, intratracheal instillation and inhalation, were also evaluated. Rats were subjected to intratracheal instillations or 4 weeks of inhalation exposure to the nanoparticles, and the 8-hydroxydeoxyguanosine (8-OHdG) levels in the lung were analyzed by an HPLC-EC detector method. The 8-OHdG levels were increased in a dose-dependent manner with the inhalation of NiO. ZnO also increased the 8-OHdG levels with inhalation. In comparison with the control, the 8-OHdG levels were significantly and persistently higher with the CeO2 nanoparticle administration, by both intratracheal instillation and inhalation. In contrast, there were no significant differences in the 8-OHdG levels between the control and TiO2 nanoparticle-treated groups, with either intratracheal instillation or inhalation during the observation period. These results indicated that NiO, ZnO and CeO2 nanoparticles generate significant amounts of free radicals, and oxidative stress may be responsible for the lung injury caused by these nanoparticles. In addition, both intratracheal instillation and inhalation exposure induced similar tendencies of oxidative DNA damage with these nanoparticles.

Chronic alcohol consumption prevents 8-hydroxyguanine accumulation in 3'-methyl-4-dimethylaminoazobenzene-treated mouse liver.

Alcohol consumption is known to have opposing effects on carcinogenesis: promotion and prevention. In this study, we examined the effects of 12% ethanol on oxidative DNA damage accumulation and its repair in mouse livers treated with 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB), a well-known hepatic carcinogen. We previously reported that 3'-MeDAB increased 8-hydroxyguanine (8-OH-Gua) accumulation and its repair activity, accompanied by the fragmentation of 8-oxoguanine DNA glycosylase 1 (OGG1), the main repair enzyme of 8-OH-Gua. The present results showed that 12% ethanol intake attenuated the 8-OH-Gua accumulation, but not the fragmentation of OGG1 induced by 3'-MeDAB. Additionally, no significant changes in oxidative status, as monitored by lipid peroxidation (LPO), were observed among the 3'-MeDAB-treated mouse livers with/without alcohol administration. These findings suggested that 12% ethanol consumption may reduce the risk of 3'-MeDAB-induced carcinogenesis by decreasing 8-OH-Gua accumulation.

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.

Detection of a mouse OGG1 fragment during caspase-dependent apoptosis: oxidative DNA damage and apoptosis.

We investigated the expression of mouse 8-oxoguanine DNA glycosylase 1 (mOGG1) in mouse non-parenchymal hepatocytes (NCTC) during etoposide- or mitomycin C (MMC)-induced apoptosis. We observed mOGG1 fragmentation in apoptotic cells. The apoptosis accompanying the fragmentation of mOGG1 was caspase-dependent. The mOGG1 fragment existed in both the cytoplasm and nucleus of the etoposide-treated NCTC, indicating that the mOGG1 fragment could be transferred into the nucleus. In addition, 8-hydroxyguanine (8-OH-Gua, 7,8-dihydro-8-oxoguanine) accumulated in the DNA of NCTC treated with etoposide, suggesting that the mOGG1 fragment might not function as a normal repair enzyme in etoposide-treated NCTC. Although we have not clarified in detail the mechanism and the significance of the mOGG1 fragmentation, further study of the fragmentation of DNA repair enzymes might provide insights into the relationship between oxidative DNA damage and apoptosis.

Detection of a smaller, 32-kDa 8-oxoguanine DNA glycosylase 1 in 3'-methyl-4-dimethylamino-azobenzene-treated mouse liver.

We previously reported that 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) increased the 8-hydroxyguanine (8-OH-Gua) content in nuclear DNA and the base excision repair activity in mouse liver. However, to understand the mechanism of 3'-MeDAB carcinogenesis, a further investigation of the 8-OH-Gua repair systems was necessary. In this report, we examined the expression of the repair enzyme, 8-oxoguanine DNA glycosylase 1 (OGG1), in 3'-MeDAB-treated mouse liver. We prepared four kinds of anti-peptide polyclonal antibodies raised against mouse OGG1 (mOGG1). The sequences used as epitopes were designed from positions located close to the N-terminus, the nuclear localization signal (NLS), and the regions containing Lys(249) and Asp(267), which are involved in the catalytic mechanisms of mOGG1 (glycosylase and lyase, respectively). Immunoblotting, using all four antibodies, revealed a 32-kDa protein (mOGG1-32) in addition to the 38-kDa mOGG1 in the 3'-MeDAB-treated mouse liver. Moreover, immunostaining with mOGG1 antibody yielded strong, positive signals in the 3'-MeDAB-treated mouse liver nuclei. However, we could not detect any difference in the Ogg1 mRNA expression pattern. Although the function of mOGG1-32 remains unclear, these findings suggest that 3'-MeDAB may alter the function of the DNA repair protein, and this action may be related to 3'-MeDAB carcinogenesis.

Changes of 8-OH-dG levels in DNA and its base excision repair activity in rat lungs after inhalation exposure to hexavalent chromium.

According to the toxicological and epidemiological studies, hexavalent chromium (Cr) is associated with increase of lung cancer risk. Genotoxic effects, such as chromosomal aberrations, and cellular oxidative DNA damage by reactive oxygen species produced by hexavalent Cr exposure may play an important role in its carcinogenesis. To clarify whether reactive oxygen species are involved in its mechanism, we examined the levels of 8-hydroxydeoxyguanine (8-OH-dG) and its base excision repair activities in the lung tissues of rats that repeatedly inhaled a sodium chromate solution mist for 1, 2, and 3 weeks. The levels of 8-OH-dG increased significantly in the lung tissues of the rats exposed for 1 week at the low concentration (0.18 mg/m(3), P<0.05), as compared with the controls. However, there was no difference in the 8-OH-dG levels at the higher concentration or with more than 2 weeks of exposure. The 8-OH-dG repair activities decreased in a dose-dependent manner during 2 weeks of exposure, on the contrary they recovered at 3 weeks of repeated exposure. These results suggest that the DNA damage caused by hexavalent Cr inhalation is induced by the generation of reactive oxygen species and by inhibition of base excision repair activity during the earlier phase of exposure. However, the 8-OH-dG levels and its repair activities recovered to the level of the controls in the latter inhalation exposure period.