Urinary 8-oxodG Research Articles

The role of oxidative stress, tumor and inflammatory markers in colorectal cancer patients: A one-year follow-up study

Oxidative stress (OS) and inflammation are known to play an important role in colorectal cancer (CRC). This study analyzed tumor, inflammatory and OS markers in CRC patients and in a control group. In addition, the evolution of these markers was evaluated after one-year of follow-up treatment. This was a longitudinal and prospective, observational study in 80 CRC patients who were candidates for tumor resection surgery and/or chemo-radiotherapy treatment and a healthy control group (n = 60). Subsequently, catalase (CAT), reduced glutathione (GSH), oxidized glutathione (GSSG) and GSSG/GSH ratio in serum and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and F2-IsoProstanes (F2-IsoPs) in urine at 1, 6 and 12 months after treatment was analyzed. Tumor markers (CEA and CA 19.9), as well as inflammatory markers—leukocytes, neutrophils, neutrophil/lymphocyte (N/L) index, platelets, fibrinogen, C-reactive protein (CRP), and interleukin 6 (IL6)— were also analyzed. As expected, levels of CEA and CA 19.9 and markers of inflammation, except CRP, were significantly higher in CRC compared to the control group. Regarding OS markers, a decrease in CAT and GSH and an increase in GSSG, GSSG/GSH ratio, 8-oxodG and F2-IsoPs were found in CRC patients compared to healthy controls at baseline. After treatment, an improvement of their inflammation profile was accompanied by a progressive recovery of antioxidant enzyme activities and the decline of oxidative byproducts both in serum and urine. Based on the results obtained, we propose the assay of urinary 8-oxodG and F2-IsoPs, as well as serum CAT, GSH, GSSG as a marker for the evaluation of OS and the clinical follow-up of CRC patients.

Selenium exposure and urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine: Major effects of chemical species and sex

Selenium is an element present in trace amounts and different chemical forms. It may exert both beneficial and adverse effects on cellular redox status and on the generation of reactive oxygen species. 8-oxo-7,8-dihydro-2′deoxyguanosine (8-oxodG) is an oxidized derivative of deoxyguanosine, and a sensitive biomarker of oxidative stress and genotoxicity.The present study assessed the extent to which selenium status was associated with urinary 8-oxodG concentrations in a Northern Italian population.We recruited healthy, non-smoking blood donors living in the Reggio Emilia province during 2017–2019. We measured urinary 8-oxodG concentrations and used restricted cubic spline regression analyses to investigate the association between selenium status (estimated using food frequency questionnaires, urinary concentrations, and serum concentrations of selenium and selenium species) and 8-oxodG/g creatinine.Among 137 participants aged 30–60 years, median urinary selenium and 8-oxodG concentrations were 22.02 μg/L and 3.21 μg/g creatinine, respectively. Serum samples and selenium speciation analyses were available for 104 participants. Median total serum selenium levels and dietary intake were 116.5 μg/L and 78.7 μg/day, respectively. In spline regression analysis, there was little association between dietary, serum, or urinary selenium with 8-oxodG concentrations. In sex-specific analyses, urinary selenium showed a positive association with the endpoint among males. For single selenium species, we observed positive associations with urinary 8-oxodG for serum organic selenium species, and negative associations for inorganic selenium forms. In the most adjusted analysis, urinary 8-oxodG concentrations showed a strong positive association with selenomethione-bound selenium (Se-Met) and a negative association with inorganic tetravalent selenium, selenite. In sex-specific analyses, these associations were considerably stronger in males than in females.Overall, study findings indicate that selenium species exhibited very different patterns of associations with the biomarker of oxidative stress, and that these associations also depended on sex. Background exposure to Se-Met appears to be strongly and positively associated with oxidative stress.

Associations of urinary and dietary cadmium with urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine and blood biochemical parameters

Cadmium is a heavy metal with established adverse effects on human health, namely on bone, liver and kidney function and the cardiovascular system. We assessed cadmium exposure and its correlation with biomarkers of toxicity. We recruited 137 non-smoking blood donors without a history of chronic disease or cancer who resided in the Northern Italy province of Reggio Emilia (mean age 47 years, range 30–60 years) in the 2017–2019 period. We used a semi-quantitative food frequency questionnaire to estimate dietary cadmium intake and urine samples to assess concentrations of urinary cadmium and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG). Median urinary cadmium and 8-oxodG concentrations were 0.21 μg/L (interquartile range (IQR): 0.11–0.34 μg/L) and 3.21 μg/g creatinine (IQR: 2.21–4.80 μg/g creatinine), respectively, while median dietary cadmium intake was 6.16 μg/day (IQR: 5.22–7.93 μg/day). We used multivariable linear and spline regression models to estimate mean differences exposure concentrations. Dietary and urinary cadmium were positively correlated, and both were positively and linearly correlated with 8-oxodG. We found a positive association of urinary cadmium with blood alanine aminotransferase (ALT), total cholesterol, low-density lipoprotein (LDL)-cholesterol and thyroid-stimulating hormone (TSH) concentrations. We also observed a positive association with triglycerides, in both linear (beta regression coefficient = 77.03, 95% confidence interval 32.27–121.78) and non-linear spline regression analyses. Despite the positive correlation between dietary and urinary cadmium estimates, dietary cadmium intake showed inconsistent results with the study endpoints and generally weaker associations, suggesting a decreased capacity to reflect actual cadmium exposure. Overall, these findings suggest that even low levels of cadmium exposure may adversely alter hematological and biochemical variables and induce oxidative stress.

Association between cadmium and genotoxicity and oxidative stress risk biomarkers in a population of Northern Italy

BACKGROUND AND AIM: Cadmium is a toxic heavy metal exerting several adverse effects in humans, especially for kidney, bone, liver, and cardiovascular system. In particular, genotoxic effects may occur through several epigenetic mechanisms, but a direct genotoxicity has been suggested. 8-oxo-7,8-dihydro-2’deoxyguanosine (8-oxodG) is an oxidized derivative of deoxyguanosine, largely used as biomarker of oxidative stress in urine. In this study, we aimed to assess cadmium levels in a population in Northern Italy, in order to evaluate the correlation between cadmium exposure with different haematological and biochemical parameters, as well as the relationship with 8-oxodG levels. METHODS: We recruited healthy and non-smoking subjects living in the Reggio Emilia province in the period 2017-2019 at the Transfusion Medicine Unit of Santa Maria Nuova Hospital, AUSL-IRCCS of Reggio Emilia, Northern Italy. Urinary cadmium and 8-oxodG, and fasting blood haematological and biochemical parameters were assessed. RESULTS:We eventually recruited 140 participants (mean age 47.4 years). Mean urinary cadmium and 8-oxodG levels were 0.25 µg/L (range: 0.01–1.33 µg/L) and 3.68 µg/g creatinine respectively. All haematological and biochemical parameters were in the normal range. We found a positive association of cadmium concentrations with alanine aminotransferase, total cholesterol, triglyceride, and TSH levels, while a negative one was observed with glycaemia, HDL levels. In addition, we found a strong positive correlation between urinary cadmium and 8-oxodG. CONCLUSIONS:Our study suggests that cadmium exposure is associated with detrimental effects on some haematological and biochemical parameters even at very low levels, generally considered safe for the general population. The positive association between urinary cadmium levels and oxidative stress, as assessed through 8-oxodG levels, highlights the potential role of this heavy metal in causing direct genotoxic effects. We acknowledge the collaboration of Transfusion Medicine Unit-Reggio Emilia Hospital personnel, AVIS-Section of Reggio Emilia staff and volunteers, and all blood donors who participated to this study. KEYWORDS: Biomarkers of exposure, Chemical exposures, Environmental epidemiology, Exposures, Heavy metals, Toxicology

Influence of skin melanisation and ultraviolet radiation on biomarkers of systemic oxidative stress

Skin melanisation ranges widely across human populations. Melanin has antioxidant properties and also acts as a filter to solar ultraviolet radiation (UVR) incident upon the skin. In this study we firstly examined whether melanin level might influence baseline levels of systemic oxidative stress, in 65 humans in vivo from the same geographical area ranging from the lightest to darkest skin type (phototype I-VI). This was examined in winter-time (latitude 53.5°N). Remarkably, we found that urinary biomarkers of oxidatively-generated DNA damage (8-oxodG) and RNA damage (8-oxoGuo) were significantly correlated with skin lightness (L*), such that 14–15% of the variation in their baseline levels could be explained by skin colour. Next we exposed 15 humans at the extremes of skin melanisation to a simulated summer-time exposure of solar UVR (95% UVA, 5% UVB; dose standardised to sunburn threshold), following which they provided a sample of every urine void over the next five days. We found that UVR induced a small but significant increase in urinary 8-oxodG and 8-oxoGuo, with differing kinetics between skin types. Thus greater melanisation is associated with protection against systemic oxidative stress, which may reflect melanin's antioxidant properties, and solar UVR exposure also influences systemic oxidative stress levels in humans. These novel findings may have profound implications for human physiology and health.

Pooled analysis of genotoxicity markers in relation to exposure in the Flemish Environment and Health Studies (FLEHS) between 1999 and 2018

BackgroundThe Flemish Environment and Health Studies (FLEHS) are human biomonitoring surveys running in Flanders since 1999. Additionally to biomarkers of exposure, markers of genotoxicity and oxidative stress have been measured, including the alkaline comet and micronucleus assay in peripheral whole blood cells, and urinary concentrations of 8-oxo-2′-deoxyguanosine (8-oxodG). AimExposure-effect associations were explored in a pooled dataset of nine different cross-sectional FLEHS surveys. Data of adolescents collected in a time frame of about 20 years (1999–2018) were compiled. The aim of the study was to examine whether increased variation in exposure, lifestyle and environmental factors would lead to more powerful and robust exposure-effect associations. Materials & methodsThe biomarkers were measured in 2283 adolescents in the age range of 14–18 years. Exposure to polycyclic aromatic hydrocarbons [1-hydroxypyrene (1-OHP)], benzene (tt’-muconic acid), metals (arsenic, cadmium, copper, nickel, thallium, lead, chromium), persistent organochlorines and phthalates were assessed in blood or urine. Furthermore, outdoor air levels of particulate matter (PM10 and PM2.5) at the residences of the youngsters were calculated. Pooled statistical analysis was done using mixed models. Study-specific differences in the genotoxicity markers and in the strength/direction of the association were accounted for. This was done by incorporating the random factor ‘study’ and a random study slope (if possible). The exposure markers were centered around the study-specific mean in order to correct for protocol changes over time. ResultsA significant association was observed for the urinary oxidative stress marker 8-oxodG, which was positively associated with 1-OHP (5% increase for doubling of 1-OHP levels, p = 0.001), and with urinary copper (26% increase for doubling of copper levels, p = 0.001), a metal involved in the Fenton reaction in biological systems. 8-oxodG was also associated with the sum of the metabolites of the phthalate di(2-ethylhexyl) phthalate (DEHP) (3% increase for doubling of the DEHP levels, p = 0.02). For those associations, data pooling increased the statistical power. However, some of the associations in the individual surveys, were not confirmed in the pooled analysis (such as comet assay and 8-oxodG vs. atmospheric PM; and 8-oxodG vs. urinary nickel). This may be due to inconsistencies in exposure-effect relations and/or variations in the pollutant mix over time and regions. ConclusionPooled analysis including a large population of 2283 Flemish adolescents showed that 8-oxodG, a marker of oxidative DNA damage is a valuable marker to assess impact of daily life pollutants, such as PAHs, Cu and the phthalate DEHP.

Influence of pubertal development on urinary oxidative stress biomarkers in adolescent girls in the New York LEGACY cohort

Puberty is a time of intense growth and differentiation of breast tissue and a window of susceptibility (WOS) for breast cancer. Although oxidative stress markers have been associated with breast cancer risk, it is unclear whether oxidative stress levels are different during the pubertal WOS, and if so, whether these differences are related to breast cancer susceptibility. We measured urinary biomarkers of whole body oxidative stress (urinary F2-Isoprostanes and 8-oxodeoxyguanosine (8-oxodG)) in 158 girls (ages 6–13 years), 71 with and 87 without a breast cancer family history (BCFH) from a cohort of adolescent girls from the New York site of the LEGACY cohort (Lessons in Epidemiology and Genetics in Adults Cancer from Youth). We compared levels of urinary oxidative stress biomarkers (F2-Isoprostanes and 8-oxodG) across the pubertal window, defined by Tanner Stage (TS) of breast development, both cross-sectionally and longitudinally within girls over an 18-month follow up period. Urinary oxidative stress biomarkers were unrelated to pubertal stages in cross-sectional analyses after considering adjustments for body mass index (BMI) and BCFH. In our longitudinal analysis, we found that urinary 8-oxodG levels, but not F2-Isoprostane levels, increased with age in BCFH + girls (β = 6.12, 95% CI = 0.08–12.16) compared to BCFH-girls. Higher BMI was associated with higher level of F2-Isoprostane in both cross-sectional (β = 0.02, 95% CI = 0.0004–0.05) and longitudinal analysis (β = 0.02, 95% CI = 0.0002–0.05). These findings support that higher BMI increases oxidative stress biomarkers over the pubertal window and that there are changes in 8-oxodG oxidative stress biomarkers in girls with a BCFH compared to girls without a BCFH.

Polycyclic aromatic hydrocarbon exposure and atherosclerotic cardiovascular disease risk in urban adults: The mediating role of oxidatively damaged DNA

Polycyclic aromatic hydrocarbon (PAH) exposure has been considered a risk factor for cardiovascular diseases (CVD), whereas possible mechanisms for this association have not been fully understood. This study focused on exploring the potential effect of oxidatively damaged DNA on the relationships between PAH exposure and the 10-year atherosclerotic CVD (ASCVD) risk. Urinary levels of monohydroxy PAH metabolites (OH-PAHs) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG, the typical biomarker for oxidatively damaged DNA) were measured among 3052 subjects in the baseline of the Wuhan-Zhuhai cohort. The relationships between urinary OH-PAHs, 8-oxodG and 10-year risk of ASCVD were analyzed by linear mixed models and logistic regression models, respectively. The mediation analysis was further applied to explore the role of 8-oxodG in the relationship between urinary OH-PAHs and 10-year ASCVD risk. After controlling for potential confounders, the log-transformed level of total urinary low molecular weight OH-PAHs (∑LMW OH-PAHs) was significantly associated with an elevated risk of 10-year ASCVD [odds ratio (OR) = 1.222, 95% confidence interval (CI): 1.065–1.402]. More specifically, significantly positive dose-response relationships between total urinary hydroxynaphthalene (∑OHNa), hydroxyfluorene (∑OHFlu), hydroxyphenanthrene (∑OHPh) and 10-year ASCVD risk were observed (all P for trend <0.05). We also found positive relationships between urinary OH-PAH levels and 8-oxodG, as well as between urinary 8-oxodG levels and 10-year risk of ASCVD. Moreover, mediation analyses indicated that urinary 8-oxodG mediated 14.49%, 12.62% and 10.55% of the associations between urinary ∑LMW OH-PAHs, ∑OHNa, ∑OHFlu and 10-year ASCVD risk, respectively. These findings suggest that the oxidatively damaged DNA pathway may be a possible mechanism underlying PAH-associated ASCVD risk elevation.

A multibiomarker approach to evaluate the effect of polyaromatic hydrocarbon exposure on oxidative and genotoxic damage in tandoor workers.

We conducted a cohort study of tandoor workers to evaluate the relationship between the biomarkers of oxidative and genotoxic damage and exposure to polyaromatic hydrocarbons. A series of oxidative and genotoxic damage biomarkers, including urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), malondialdehyde (MDA) content, and tail moment (TM) by comet assay, was studied. A total of 76 tandoor workers and 79 demographically matched healthy individuals as controls were included. Our results showed that the tandoor workers had significantly higher urinary levels of 1-hydroxypyrene, urinary 8-OHdG, MDA content, and TM compared with the control population. The concentration of all these biomarkers increased with age in the control population as well as tandoor workers. In tandoor workers, significant variation in MDA, 8-oxodG (8-oxo-2'-deoxyguanosine) and TM concentration was detected between smokers (5.08 ± 1.72 nmol/mL, 16.01 ± 4.94 ng/mg creatinine, and 5.87 ± 0.98 µm, respectively) and nonsmokers (3.84 ± 0.98 nmol/mL, 13.74 ± 3.60 ng/mg creatinine, and 5.32 ± 0.69 µm, respectively). A similar pattern was obtained for the control population. We did not obtain significant variations for alcoholics and tobacco chewers. A significant increase in all these three biomarkers was observed with the increase in the period of work exposure in tandoor workers. Multivariate regression analysis also revealed that urinary 8-oxodG, MDA, and TM were statistically significantly related to age and period of work exposure. Overall, the present study showed that the exposure to wood smoke in tandoor workers under occupational conditions led to increased DNA damage because of oxidative stress and genotoxicity. These biomarkers, therefore, are good indices to assess oxidative DNA damage in these workers exposed to occupational genotoxicants. It is also necessary to make preventive changes in work conditions and lifestyle, which will help these occupational workers to lead a healthy life.

Urinary and exhaled biomarkers of exercise-induced bronchoconstriction in atopic asthmatic children.

Exercise-induced bronchoconstriction (EIB) reflects poor asthma control. Assessing noninvasive biomarkers associated with EIB could help to monitor patients in the pediatric age. To test exhaled and urinary biomarkers for assessing EIB in atopic asthmatic children. In 45 atopic patients (11.1 ± 1.8 years, 25 males) we measured the fractional exhaled nitric oxide (FENO ), its alveolar (CaNO), and bronchial (J'awNO) components corrected for the trumpet shape of the airways and axial NO diffusion (TMAD), concentrations of urinary adenosine and 8-hydroxy-2'-deoxyguanosine (8-OxodG), blood eosinophils count, total immunoglobulin E , skin prick tests, and baseline spirometry before a treadmill exercise challenge. Forty healthy control subjects participated solely to baseline measurements. Patients yielded higher FENO and urinary adenosine concentrations than healthy controls. After the challenge, 18 patients (40%) had EIB; these patients had higher levels of CaNO, CaNO TMAD, and urinary adenosine than patients without EIB. Baseline spirometry, FE NO , JawNO, JawNO TMAD, urinary 8-OxodG, allergy, and blood eosinophil counts were found similar in both groups. In multiple linear regression, the fall in FEV 1 was explained by CaNO TMAD, urinary adenosine and blood eosinophil count, whereas the fall in FEF 25-75 was explained by CaNO TMAD and blood eosinophil count. Both CaNO TMAD ≥10.5 ppb and urinary adenosine ≥406 nmol/mmol Cr predicted a fall in FEV 1 ≥10%, while only CaNO TMAD ≥10.5 ppb predicted a fall in FEF 25-75 ≥26%. Concentrations of peripheral airway NO are complementary with urinary adenosine for assessing EIB and promising tools of asthma control in pediatric patients with the atopic phenotype.

Classification and Temporal Variability in Urinary 8-oxodG and 8-oxoGuo: Analysis by UHPLC-MS/MS

Oxidative stress damage has been found to be associated with exposure of children to environmental pollutants, but there are few data on the variability of urinary oxidative stress biomarkers and the accuracy of biomarker concentration classification. We performed a longitudinal study in Chinese school-aged children to investigate the variability of urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) concentrations and the ability of a single first morning urine sample to assess accuracy and sensitivity of biomarkers concentration classification. After adjusting for both creatinine and specific gravity, we characterized the distribution and reproducibility of repeated measurement of 8-oxodG and 8-oxoGuo by using intraclass correlation coefficients (ICCs) derived from linear mixed model and performed surrogate category analyses to determine whether a single spot sample could accurately classify 8-oxodG and 8-oxoGuo levels. Results indicated that the geometric mean (GM) concentrations of 8-oxodG and 8-oxoGuo were 3.865 ng/mL and 5.725 ng/mL, respectively. High variability of 8-oxodG and 8-oxoGuo was observed in the single spot first morning urine sample (ICC = 0.25 and 0.18, respectively). Three repeated urinary specimens achieved sensitivity of 0.87 for 8-oxodG and 0.83 for 8-oxoGuo in low tertile and sensitivity of 0.78 in high tertile. But classification in medium tertile was less accurate for both 8-oxodG and 8-oxoGuo. In conclusion, high variability of urinary 8-oxodG and 8-oxoGuo levels results in repeated samplings needed for accurate classification.

Associations between polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furans exposure and oxidatively generated damage to DNA and lipid

Polychlorinated dibenzo-dioxins and polychlorinated dibenzo-furans (PCDD/Fs) have been reported to induce reactive oxygen species and oxidative stress, but the dose-response relationships have not been explored in molecular epidemiological studies. In this study, a total of 602 participants were recruited, comprising of 215 foundry workers, 171 incineration workers and 216 residents living more than 5 km away from the plants as the reference group. Individual PCDD/Fs exposures were estimated according to PCDD/Fs levels of working and living ambient air and daily foods. Urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and 8-iso-prostaglandin-F2α (8-isoPGF2α) were determined to reflect oxidatively generated damage to DNA and lipid. Generalized linear models were used to access the associations between PCDD/Fs exposure and oxidative stress biomarkers. We found that PCDD/Fs exposure and urinary oxidative stress biomarkers of workers were all higher than those of the reference group. Significantly positive exposure-response relationships between individual PCDD/Fs exposures and urinary 8-oxodG and 8-iso-PGF2α were found. Each 1-unit increase in ln-transformed levels of PCDD/Fs exposure generated a 0.78 nmol/mmol creatinine increase in ln-transformed 8-oxodG and a 0.50 ng/mmol creatinine increase in ln-transformed 8-isoPGF2α in foundry workers, a 0.49 nmol/mmol creatinine increase in ln-transformed 8-oxodG and a 0.26 ng/mmol creatinine increase in ln-transformed 8-isoPGF2α in incineration workers, compared with the reference group. And such associations were not modified by tobacco use. Our findings could help to understand the dose-response relationships between PCDD/Fs and oxidatively generated damage to DNA and lipid, and provide an epidemiologic basis for conducting research on the carcinogenesis and other toxicity mechanisms of PCDD/Fs.

Statin treatment, oxidative stress and inflammation in a Danish population

BackgroundWhile statins may have anti-inflammatory effects, anti-oxidative effects are controversial. We investigated if statin treatment is associated with differences in oxidatively generated nucleotide damage and chronic inflammation, and the relationship between nucleotide damage and chronic inflammation. MethodsWe included 19,795 participants from the Danish General Suburban Population Study. In 3420 participants, we measured urinary 8-oxodG and 8-oxoGuo by liquid chromatography-tandem mass spectrometry as markers of oxidatively generated damage to DNA and RNA, respectively. We used a composite score for chronic inflammation (INFLA score) of hsCRP, WBC, platelet count, and neutrophil granulocyte to lymphocyte ratio. Associations were assessed using multivariate linear regression models. ResultsCompared with non-users, statin users had 4.3–6.0% lower 8-oxodG in three separate models (p < 0.05); there were no differences in 8-oxoGuo. Among participants aged > 60 y, statin users had 11.4% lower 8-oxodG (95%CI: 6.7–15.9%, pinteraction<0.001) and 3.9% lower 8-oxoGuo (95%CI: 0.1–7.5%, pinteraction = 0.002), compared with non-users. Compared with non-users, statin users had 11.1% (95%CI: 5.4–16.5%, pinteraction<0.001) lower 8-oxodG in participants treated for hypertension, and 18.6% (95%CI: 6.8–28.9%, pinteraction<0.001) lower 8-oxodG in participants with decreased renal function. Compared with non-users, statin users had significantly lower INFLA score (p < 0.001). 8-oxodG and 8-oxoGuo associated positively with markers of chronic inflammation. ConclusionsOxidatively generated DNA damage and inflammatory burden are lower in statin users compared with non-users. Together, anti-oxidative and anti-inflammatory effects may contribute to the beneficial effects of statins.

Comparison of an HPLC-MS/MS Method with Multiple Commercial ELISA Kits on the Determination of Levels of 8-oxo-7,8-Dihydro-2'-Deoxyguanosine in Human Urine

Introduction: Analysis of 8-oxodG is usually conducted by either chromatography-based methods or by immunochemical methods commonly used based upon their low cost and high-throughput. However, concern regarding the accuracy of ELISA methods has complicated their use. We directly compare the levels of urinary 8-oxodG obtained by HPLC-MS/MS with three commercially available ELISA kits in this report. Methods: In the current study, a total of 9 human urine samples were analyzed by LC-MS/MS and three commonly used commercial available ELISA kits. Results: We found that urinary 8-oxodG levels analyzed by HPLC-MS/MS [1.4 ± 0.3 nmol/mmol creatinine) were 7.6- to 23.5-fold lower than those detected by ELISA. Overall, the correlations between ELISA and HPLC-MS/MS were poor but were improved after SPE purification for kits from ENZO (P = 0.2817 without SPE; P = 0.0086 with SPE) and Abcam (P = 0.0596 without SPE; P = 0.0473 with SPE). Discussion and conclusion: While we confirmed that SPE purification can improve the correlation between the selected ELISA kits and HPLC-MS/MS, HPLC-MS/MS is still the method of choice to accurately assess the levels of 8-oxodG in human urine.

174 - Chronic low level oxidative stress in primary hyperoxaluria type 1

The Primary Hyperoxalurias (PH’s) are a family of inborn errors of glyoxylate metabolism resulting in excessive production of endogenous oxalate and PH1 is the most severe form of this disorder. There is no cure and treatment options are limited due to a poor understanding of the underlying pathology. Based on previously published reports we hypothesize that oxidative stress may play a unique role in PH1. In the absence of alanine-glyoxylate aminotransferase (AGT), the liver specific enzyme deficient in PH1, a futile redox cycle can occur between glycolate oxidase (GO) and glyoxylate reductase (GR). GO produces hydrogen peroxide and GR consumes NADPH. This mechanism points to a potential alteration in redox environment that has not yet been studied. Therefore, we performed a comprehensive global proteomics study comparing livers of PH1 mice to WT mice. In this study we found 155 significantly altered proteins, including 36 redox related proteins. PH1 model mice at experimental age show no phenotypic difference except for increased oxalate excretion. This data, combined with the use of Systems/ Pathway analysis, strongly suggests that PH1 mice are experiencing oxidative stress. Interestingly, functional data did not fully reflect these findings. mtDNA damage was not significantly changed in PH1 vs. WT using an XLPCR technique, nor was urinary 8-oxodG using an ELISA kit. However, GSH levels were significantly lower in PH1 mice measured by HPLC-ECD. All together this evidence suggests that the PH1 mouse is experiencing chronic low levels of oxidative stress that the mouse is compensating for at the proteomic level. Therefore, we have concluded that the redox related proteins have been modified in order to cope with an otherwise undetectable change in oxidative stress. We believe this is a highly unusual multi-tool approach and finding that the standard oxidative stress related tools would have missed if carried out alone.

Evaluation of a short term effect of praziquantel treatment in opisthorchiasis-induced hepatobiliary inflammation by urinary 8-oxodG

Inflammation of the hepatobiliary system in chronic opisthorchiasis is associated with an elevated level of urinary 8-oxo-7,8 dihydro-2′deoxyguanosine (8-oxodG) during active as well as past exposure to Opisthorchis viverrini infection. In this study, we evaluated the short-term effect of praziquantel treatment on hepatobiliary disease (HBD) using urinary 8-oxodG as an inflammatory marker in a cohort of residents in endemic areas of opisthorchiasis in Khon Kaen, Thailand. The HBD status in terms of periductal fibrosis (PDF) was determined by abdominal ultrasonography and O. viverrini infection was monitored at baseline and 2–4 weeks after curative treatment by praziquantel. Analysis of O. viverrini-infected participants who were PDF-ve revealed that there was a significant reduction of urinary 8-oxodG after treatment compared with the baseline levels (p < 0.001). By contrast, in PDF+ve individuals, the levels of urinary 8-oxodG were similar between baseline and those post-treatment. Although confirmation by using a larger sample size is needed, the positive association between HBD and urinary 8-oxodG level after worm clearance suggests that chronic hepatobiliary inflammation is neither affected nor interrupted by short-term praziquantel treatment. Individuals with persistent PDF at pre- and post-treatment who have a high risk of cholangiocarcinoma, could be identified within 2–4 weeks after parasite removal by drug treatment. Thus, urinary 8-oxodG is a useful biomarker for predicting persistent PDF in individuals with a recent drug treatment history who require further clinical investigation, management and treatment.

Elevated urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine and serum uric acid are associated with progression and are prognostic factors of colorectal cancer.

Background and purposeOxidative stress is closely related to the pathogenesis of colorectal cancer (CRC). 8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) is a typical bio-marker of oxidative stress. Serum uric acid (SUA) is one of the most abundant molecules with antioxidant properties in human blood. This study aimed to explore whether 8-oxodG and SUA could be prognostic factors of CRC.MethodsUrinary 8-oxodG level was analyzed using ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). SUA concentration was measured using an automatic biochemistry analyzer. Seventy-three newly diagnosed Chinese CRC patients were included. According to the mean level of urinary 8-oxodG or SUA, patients were divided into high and low groups.ResultsThe level of 8-oxodG and SUA gradually elevated from stage I to stage IV in CRC patients. High 8-oxodG concentration and SUA levels were associated with worse overall survival (P=0.03). In the stage II and stage III CRC group, no statistically significant relationship was found between the urinary 8-oxodG level and overall survival or between the SUA level and overall survival. Nevertheless, when these two biomarkers were combined, there was a statistically significant association with overall survival (P=0.02).ConclusionElevated urinary 8-oxodG and SUA levels measured at the time of diagnosis were associated with the progression of CRC. Both urinary 8-oxodG and SUA might be valuable as CRC prognostic factors, and the combination of the two biomarkers might help to determine the prognoses of CRC, particularly in stage II and stage III CRC patients.

Elevated levels of 8-oxoGuo and 8-oxodG in individuals with severe mental illness – An autopsy-based study

Elevated systemic oxidative stress levels of 8-oxoGuo and 8-oxodG have been reported in individuals with severe mental illness (SMI). As no previous studies have addressed the link between local levels of 8-oxoGuo and 8-oxodG in the central nervous system (CNS), measured in cerebrospinal fluid (CSF), and urinary systemic levels, we employed autopsy-based material to elucidate this aspect. Additionally, we investigated the impact of 8-oxoGuo and 8-oxodG levels on the prevalence of somatic co-morbidities.Based on post mortem samples from deceased individuals with SMI (N = 107), we found significantly elevated urinary levels of both 8-oxoGuo and 8-oxodG compared to mentally healthy living controls. While we found an association between urinary and CSF 8-oxodG levels (r = 0.50, P < 0.001), a similar correlation was not evident for 8-oxoGuo (r = 0.15, P = 0.16). Additionally, the two r-values were significantly different (P < 0.001). Neither marker in urine or CSF was associated with obesity-related variables, metabolic syndrome or type 2 diabetes. The post mortem interval did not affect the results, but the agonal phase seemingly introduced bias.This study provided novel insights into the cellular oxidative stress levels in individuals with SMI. We demonstrated that increased oxidative stress locally and systemically is correlated and is a clear phenomenon in SMI. Although post mortem measurements contain some weaknesses, our study indicates DNA as the main site of oxidative stress modifications in the CNS in SMI. This may provide novel opportunities for treatment modalities. Additionally, our study demonstrated the applicability of post mortem material investigating systemic and local 8-oxoGuo and 8-oxodG levels.

Mutagenic and DNA repair activity in traffic policemen: a case-crossover study

BackgroundEmissions from vehicles are composed of heterogeneous mixtures of hazardous substances; several pollutants such as Polycyclic Aromatic Hydrocarbons (PAHs) are amongst the most dangerous substances detected in urban monitoring. A cohort of traffic policemen usually occupationally exposed to PAHs present in the urban environment were examined in order to assess the mutagenicity and DNA capacity repair.MethodsSeventy-two urban traffic policemen working in Catania’s metropolitan area were enrolled in the study. Two spot urine samples were collected from each subject during the whole working cycle as follows: sample 1 (S1), pre-shift on day 1; sample 2 (S2) post-shift on day 6. 1-hydroxypyrene (1-OHP) was measured to serve as an indirect exposure indicator. Urinary mutagenic activity was assessed through the plate incorporation pre-incubation technique with S9, using YG1024 Salmonella typhimurium strain over-sensitive to PAH metabolite. Concentrations of urinary 8-oxodG were measured using liquid chromatography tandem mass spectrometry.ResultsAs regards the exposure to PAHs, results highlighted a statistically significant difference (p < 0.001) between pre-shift on day 1 and post-shift on day 6 levels. Mutagenic activity was detected in 38 (66%) workers on S1 and in 47 (81%) on S2. Also 8-oxodG analysis showed a statistically significant difference between S1 and S2 sampling.ConclusionsThis study demonstrated that occupational exposure to pollutants from traffic emission, assessed via 1-OHP measurements in urine, may lead to DNA repair and mutagenic activity, in line with other studies.

Elevated Levels of Urinary 8-oxodG Correlate with Persistent Periductal Fibrosis after Praziquantel Treatment in Chronic Opisthorchiasis.

Previous studies demonstrated that urinary 8-oxodG is a predictive biomarker for Opisthorchis viverrini (OV)-associated hepatobiliary disease (HBD) and cholangiocarcinoma (CCA). This study examined the effects of praziquantel treatment on the profile of urinary 8-oxodG in relation to HBD status. Infection with OV, levels of urinary 8-oxodG, and HBD status in terms of periductal fibrosis (PDF) assessed by abdominal ultrasonography (US) were monitored and compared in cohorts of participants in Khon Kaen, Thailand, before and 1 year after praziquantel treatment. Urinary 8-oxodG levels significantly decreased after treatment compared with the baseline level in OV-infected participants who had no HBD (PDF negative; PDF-ve) (N = 14). Levels of 8-oxodG were unchanged after treatment in OV-infected subjects (OV+ve) who had positive PDF (N = 52). Within the positive PDF (PDF+ve) group who became PDF-ve after treatment, there was no significant change in 8-oxodG levels between pre-and posttreatment (reversible PDF = 65.3%). In those who had persistent PDF+ve at both ultrasound sampling points, there was no significant difference in urinary 8-oxodG levels between pre- and posttreatment (persistent PDF = 34.6%). Based on a logistic regression model and receiver operation curve analysis, the increase of 8-oxodG levels was found to be associated with increasing risk of PDF. Measurement of urinary 8-oxodG and US increased the likelihood of discovering persistent PDF, which is a predictable condition for the patients at risk of OV-associated CCA. To identify high-risk individuals for CCA, it is useful to perform US in combination with urinary 8-oxodG measurement.