Urinary 8-oxodG Levels Research Articles

Ferritin as a potential disease marker in patients with bipolar disorder

BackgroundLow-grade inflammation and oxidative stress have been implicated as potential pathophysiological processes in bipolar disorder, but the underlying mechanism is unknown. Ferritin is a marker of iron stores and involved in redox processes and inflammation but its role in bipolar disorder is unclear. MethodsWe investigated the possible association of increased plasma ferritin levels and bipolar disorder. We pooled two studies using similar longitudinal repeated measures designs and included 330 blood- and urinary samples from 95 patients with bipolar disorder across all affective states and 84 samples from 84 healthy control individuals. Plasma ferritin was measured along with multiple blood inflammatory markers and urinary markers of oxidatively generated damage to DNA and RNA. ResultsPlasma ferritin levels, adjusting for multiple demographical- and lifestyle variables, did not differ between patients with bipolar disorder compared with healthy control individuals (b = 1.09, 95 % CI: 0.86 to 1.39, p = 0.49). Within patients with bipolar disorder ferritin levels were higher in a depressed state compared with euthymia (b = 1.12, 95 % CI: 1.01 to 1.24, p < 0.04), and ferritin levels were positively associated with Interleukin-18 blood levels and urinary levels of 8-oxodG. LimitationsPatients with bipolar disorder received medication which could potentially influence iron metabolism. ConclusionElevated ferritin levels in depressed patients with bipolar disorder may point to a role for iron metabolism in bipolar disorder pathophysiology, and potentially as a biomarker, linking low-grade inflammation with redox biology and the well-known increased risk of medical comorbidity and reduced life expectancy.

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 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.

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.

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.

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.

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.

Urinary Markers of Oxidative Stress Are Associated With Albuminuria But Not GFR Decline

IntroductionMarkers of oxidative stress increase with age and are prevalent with chronic kidney disease. However, the role of oxidative stress markers as predictors for kidney function decline in the general population is unclear.MethodsWe investigated whether a baseline urinary excretion of oxidative DNA damage (8-oxo-7,8-dihydro-2′-deoxyguanosine [8-oxodG]) and oxidative RNA damage (8-oxo-7,8-dihydroguanosine [8-oxoGuo]) was associated with the age-related glomerular filtration rate (GFR) decline or incident low-grade albuminuria during a median of 5.6 years of follow-up. In the Renal Iohexol Clearance Survey in the Sixth Tromsø Study, we measured GFR using iohexol clearance in 1591 participants without renal disease, diabetes, or cardiovascular disease. Low-grade albuminuria was defined as an albumin-creatinine ratio >1.13 mg/mmol.ResultsThe mean (SD) annual GFR change was −0.84 (2.00) ml/min per 1.73 m2 per year. In linear mixed models, urinary 8-oxodG and 8-oxoGuo levels were not associated with the GFR change rate. In a multivariable adjusted logistic regression model, a baseline urinary 8-oxoGuo in the highest quartile was associated with an increased risk of low-grade albuminuria at follow-up (odds ratio: 2.64; 95% confidence interval: 1.50–4.65). When the highest quartile of urinary 8-oxoGuo was added to the baseline model, the area under the receiver operating characteristics curve for predicting low-grade albuminuria at follow-up improved from 0.67 to 0.71 (P = 0.002).ConclusionOxidative stress measured as urinary 8-oxoGuo excretion was independently associated with incident low-grade albuminuria, but neither 8-oxoGuo nor 8-oxodG predicted an accelerated age-related GFR decline in a cohort representative of the middle-aged general population during almost 6 years of follow-up.

URINARY MARKERS OF OXIDATIVE DNA DAMAGE IN TYPE 1 DIABETIC CHILDREN: RELATION TO MICROVASCULAR COMPLICATIONS

Objective: Type 1 diabetes mellitus (T1DM) is a widespread metabolic disease, which frequently carries with it a significant impact on human health. Oxidative damage and tissue inflammation have been claimed to be a typical pathogenic component for the progression of diabetic complications. We aim in this study to explore the relation of urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) (as a marker of nucleic acid oxidation) to microvascular complications in T1DM.Methods: A case–control study, enrolling 45 T1DM children and an equivalent number of healthy subjects, was performed. Full clinical examination and anthropometric measurement were performed to all subjects. Urinary assessment for 8-oxodG and albumin was done in addition to blood sampling for lipid profile and glycated Hb (HbA1c) assay. Complete ocular examination for assessment of diabetic retinopathy (DR) was also done.Results: Levels of urinary 8-oxodG, serum cholesterol, triglycerides, and low-density lipoprotein in cases were significantly higher than non-diabetics; these levels were likewise higher in uncontrolled T1DM patients in comparison with well-controlled T1DM subjects. Urinary 8-oxodG and HbA1c were significantly higher in diabetic patients with albuminuria and DR compared to patients without complications. Significant positive correlation was found between 8-oxodG with HbA1c (r=0.8, p&lt;0.01), diastolic blood pressure (DBP) (r=0.4, p=0.02), and cholesterol (r=0.4, p=0.05).Conclusion: Urinary 8-oxodG was found to be a reliable marker for assessing oxidative DNA damage in T1DM and can be used in the determination of microvascular complications related to diabetes.

Aging with higher fractional exhaled nitric oxide levels are associated with increased urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine concentrations in elder females.

Indoor air pollutants from environmental tobacco smoke and cooking fume can induce oxidative stress and inflammatory response, which generate oxidatively damaged DNA in human body. Among 2224 adults, levels of FENO and urinary 8-oxodG were measured using a nano coulomb nitric oxide analyzer and a high performance liquid chromatography system with electrochemical detector, respectively. Association between aging with higher FENO levels and urinary 8-oxodG levels were analyzed using multiple linear regression analysis. Nonsmoking women aged 64years and over, with higher FENO (≥ 25 part per billion) and self-catering but without passive smoking had a higher risk of increased urinary 8-oxodG (△% of urinary 8-oxodG: 81.3%, 95% CI: 27.4-158.0%) levels, particularly these elderly women with using liquefied petroleum gas for cooking, had a higher risk for increased urinary 8-oxodG levels (△% of urinary 8-oxodG: 100.2%, 95% CI: 95% CI: 35.3-196.3%), compared with those aged less than 64years, with lower FENO (< 25 part per billion). Cooking activity aggravated aging-related the aging-induced in urinary 8-oxodG excretion among nonsmoking women aged 64years and over but without passive smoking.

Increased levels of oxidative stress biomarkers in metal oxides nanomaterial-handling workers

This study assessed oxidatively damaged DNA and antioxidant enzyme activity in workers occupational exposure to metal oxides nanomaterials. Exposure to TiO2, SiO2, and ITO resulted in significant lower antioxidant enzymes (glutathione peroxidase and superoxide dismutase) and higher oxidative biomarkers 8-hydroxydeoxyguanosine (8-oxodG) than comparison workers. Statistically significant correlations were noted between plasma and urine 8-oxodG, between white blood cells (WBC) and urine 8-oxodG, and between WBC and plasma 8-oxodG. In addition, there were significant negative correlations between WBC 8-oxodG and SOD and between urinary 8-oxodG and GPx levels. The results showed that urinary 8-oxodG may be considered to be better biomarker.

Reduction in oxidative stress biomarkers after adenotonsillectomy

ObjectivesA number of otolaryngic conditions such as chronic tonsillitis, adenoid hypertrophy, and obstructive sleep apnea are associated with oxidative stress and elevated levels of serum oxidants. The objective of this study is to measure changes in urine biomarkers of oxidative stress in children after adenotonsillectomy. MethodsTwenty-two children with sleep disordered breathing (SDB) with tonsil and adenoid hypertrophy were enrolled prior to adenotonsillectomy. Controls consisted of 20 healthy children. Urine samples were collected from all patients. Levels of three urinary biomarkers for oxidative status, 8-hydroxy-2-deoxyguanosine (8-OxodG), F2-isoprostane, and malondialdehyde (MDA) were measured using high performance liquid chromatography. For the study group, urine samples were repeated 3 weeks after surgery. ResultsIn the study group, preoperative urinary levels of 8-OxodG were higher than in controls (p=0.015). Levels decreased after surgery compared to preoperative levels (p=0.002), and reached control levels (p=0.167) at 3 weeks. Levels of urinary F2-isoprostane were similar in both groups (p=0.252), but decreased significantly after surgery (p=0.020). ConclusionsChildren with SDB have elevated levels of urinary 8-OxodG, a marker of oxidative stress. Adenotonsillectomy results in decreased 8-OxodG and F2-isoprostane. These findings suggest that urine analysis may represent a valuable tool for the measurement of oxidative stress.

Reduced Coenzyme Q10 Decreases Urinary 8-Oxo-7,8-Dihydro-2'-Deoxyguanosine Concentrations in Healthy Young Female Subjects.

It remains unclear whether dietary supplementation with coenzyme Q10 (CoQ10) provides beneficial effects for healthy individuals, especially young subjects. This study investigated the effects of dietary supplementation with CoQ10 on oxidative stress in healthy young females. We performed a placebo-controlled trial using a crossover design (n=28) with 100 mg/day CoQ10 in reduced form or placebo, each lasting 2 weeks with a 2-week interval. The urinary levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a biomarker of oxidative DNA damage, were determined by high-performance liquid chromatography (HPLC) coupled to an electrochemical detector. Levels of malondialdehyde (MDA), a biomarker of lipid peroxidation, and antioxidant vitamin C in urine were also measured using a thiobarbituric acid-reactive substance method with a commercial kit and by the 2,4-dinitrophenylhydrazine method with HPLC, respectively. Urinary 8-oxodG levels during supplementation with reduced form of CoQ10 (median [first and third quartiles]: 1.76 [1.24-2.08] nmol/mmol creatinine) were significantly lower than those with placebo (2.00 [1.34-2.49] nmol/mmol creatinine, P=.031 by Student's paired t-test using the logarithmically transformed values). In contrast, the urinary levels of MDA and vitamin C were not significantly affected (P=.094 and P=.247 by Student's paired t-test, respectively). There was no evidence of any side effects. Supplementation with CoQ10 in the reduced form showed a slightly protective effect against oxidative DNA damage even in healthy young subjects.

8-Oxo-7,8-dihydro-2’-deoxyguanosine, reactive oxygen species and ambulatory blood pressure in African and Caucasian men: The SABPA study

Various studies indicate a relationship between increased oxidative stress and hypertension, resulting in increased DNA damage and consequent excretion of 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG). The aim of this study was to compare urinary 8-oxodG levels in African and Caucasian men and to investigate the association between ambulatory blood pressure (BP) and pulse pressure (PP) with 8-oxodG in these groups.We included 98 African and 92 Caucasian men in the study and determined their ambulatory BP and PP. Biochemical analyses included, urinary 8-oxodG, reactive oxygen species (ROS) (measured as serum peroxides), ferric reducing antioxidant power (FRAP), total glutathione (GSH), glutathione peroxidase (GPx) and glutathione reductase (GR) activity.The African men had significantly higher systolic (SBP) and diastolic blood pressure (DBP) (both p < 0.001). Assessment of the oxidative stress markers indicated significantly lower 8-oxodG levels (p < 0.001) in the African group. The African men also had significantly higher ROS (p = 0.002) with concomitant lower FRAP (p < 0.001), while their GSH levels (p = 0.013) and GR activity (p < 0.001) were significantly higher. Single and partial regression analyses indicated a negative association between urinary 8-oxodG levels with SBP, DBP and PP only in African men. These associations were confirmed in multiple regression analyses (SBP: R2 = 0.41; β = −0.25; p = 0.002, DBP: R2 = 0.30; β = −0.21; p = 0.022, PP: R2 = 0.30; β = −0.19; p = 0.03).Our results revealed significantly lower urinary 8-oxodG in African men, accompanied by a negative association with BP and PP. We propose that this may indicate a dose-response relationship in which increased oxidative stress may play a central role in the up-regulation of antioxidant defence and DNA repair mechanisms.

Urinary 8-hydroxy-2′-deoxyguanosine (8-oxodG) level can predict acute renal damage in young children with urinary tract infection

Background: There are no good biomarkers to predict renal parenchymal involvement in children with urinary tract infection (UTI).Methods: Children (N = 73) younger than 5 years with UTI were enrolled. Urinary levels of 8-hydroxy-2′-deoxyguanosine (8-oxodG) and total antioxidant capacity (TAC) were checked as markers of oxidative stress and antioxidant capacity, respectively. Tc99m-dimercaptosuccinic acid (DMSA) renal scintigraphy was used to find evidence of renal involvement.Results: Patients with positive DMSA findings had higher levels of urinary 8-oxodG (p = 0.003) and higher urinary TAC (p = 0.001) than patients with normal DMSA findings.Conclusions: High level of urinary 8-oxodG may be a risk factor of severe renal damage.

Diurnal variation of urinary markers of nucleic acid oxidation

Aims. Urinary 8-oxo-7,8-dihydro-2ʹ-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) are biomarkers of oxidative stress with clinical potential in a variety of diseases. As part of their clinical validation, this study aimed to investigate whether the urinary excretion of 8-oxodG and 8-oxoGuo undergoes diurnal variation and to evaluate the validity of 6-hour sampling as well as creatinine corrected spot urine sampling. Methods. A total of 23 healthy study subjects collecting their 24-h urine in four fractions covering 6 hours each. Urinary 8-oxodG and 8-oxoGuo levels were quantified using a modified version of UPLC-MS/MS. Results. No significant difference in excretion levels between the 12-h diurnal and 12-h nocturnal state or between the four 6-h periods during the day was found for either biomarker. A strong linear relationship between the excretion levels in each of the 6-h periods and the 24-h excretion level was shown for both biomarkers. Creatinine correction of the 6-h levels reduced the biological variation of the excretion levels and weakened the linear relationship with the uncorrected 24-h excretion level for both biomarkers. The correlations were strengthened when the 24-h excretion level was expressed per kg body weight. Conclusion. The results showed that 8-oxodG and 8-oxoGuo did not undergo diurnal variation in the study population overall and hence that the time of sampling is not crucial. Furthermore, 6-h sampling can be used as a substitute for 24-h sampling, and creatinine corrected sampling may be rational due to the reduction in biological variation of the biomarkers and the reasonable correlation with body weight-adjusted 24-h levels.

Urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine values determined by a modified ELISA improves agreement with HPLC–MS/MS

ELISA is widely used for urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) analysis. It is the method of choice for laboratories that lack specialized chromatographic instrumentation. It allows fast, high-throughput sample analysis without a need for extensive samples processing. However, a lack of agreement between ELISA and chromatographic methods confines its application to the assessment of relative urinary 8-oxodG levels. We investigated various ELISA modifications, seeking optimal conditions that would yield a good agreement between ELISA and high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS /MS). Purification of urine by solid phase extraction (SPE), then incubation with the anti-8-oxodG antibody at 4°C overnight and subsequent normalization of 8-oxodG levels per urinary creatinine resulted in a near-perfect correlation and agreement in mean levels between ELISA and HPLC–MS /MS (r=0.917, p<0.001; and paired t-test p=0.803, respectively). Our data show that, after introduction of a simple modification, ELISA quantification urinary 8-oxodG substantially improves. Although more sample manipulation is required, the method retains its key advantages over chromatography (high-throughput analysis that does not require expensive instrumentation). This represents a significant advance for the ELISA, and encouraging its use in more studies adding to our knowledge of the role of this biomarker of oxidative stress in health and disease.