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Exocyclic DNA adducts are considered as potential tools for the study of oxidative stress-related diseases, but an important aspect is their chemical reactivity towards oxidant species. We report here the oxidation of 1-N2-etheno-2'-deoxyguanosine (1,N2-εdGuo) by singlet molecular oxygen (1O2) generated by a non-ionic watersoluble endoperoxide [N,N'-di(2,3-dihydroxypropyl)-1,4- naphthalenedipropanamide endoperoxide (DHPNO2)] and its corresponding oxygen isotopically labeled [18O]-[N,N'- di(2,3-dihydroxypropyl)-1,4- naphthalenedipropanamide endoperoxide (DHPN18O2)], and by photosensitization with two different photosensitizers [methylene blue (MB) and Rose Bengal (RB)]. Products detection and characterization were achieved using high performance liquid chromatography (HPLC) coupled to ultraviolet and electrospray ionization (ESI) tandem mass spectrometry, and nuclear magnetic resonance (NMR) analyses. We found that dGuo is regenerated via reaction of 1O2 with the ε-linkage, and we propose a dioxetane as an intermediate, which cleaves and loses the aldehyde groups as formate residues, or alternatively, it generates a 1,2-ethanediol adduct. We also report herein the quenching rate constants of 1O2 by 1,N2-εdGuo and other etheno modified nucleosides. The rate constant (kt) values obtained for etheno nucleosides are comparable to the kt of dGuo. From these results, we suggest a possible role of 1O2 in the cleanup of etheno adducts by regenerating the normal base. [ABSTRACT FROM AUTHOR]

There is limited knowledge of association between arsenic exposure and telomere length (TL) and signal joint T-cell receptor excision circle (sjTREC) that are potential biomarkers of immune senescence and disease susceptibility. We aimed to clarify whether long-term inorganic arsenic exposure influences TL and sjTRECs in childhood. Children born in a longitudinal mother-child cohort were followed-up at 4.5 (n = 275) and 9 years (n = 351) of age. Arsenic exposure was assessed by metabolite concentrations in urine (U-As) from mothers at gestational week 8 (prenatal) and their children at 4.5 and 9 years. TL and sjTRECs were determined in blood cells using quantitative PCR. The oxidative DNA damage marker 8-hydroxy-2ʹ-deoxyguanosine (8-OHdG) in plasma was measured by ELISA. In multivariable-adjusted spline regression analyses, both prenatal and childhood arsenic exposure above U-As of 45 µg/l were significantly inversely associated with TL and sjTRECs at 9 years. Fraction of monomethylarsonic acid (MMA) above spline knot 7% were significantly inversely associated with both TL and sjTRECs reflecting increased toxicity due to less-efficient arsenic metabolism in 9--year-old children. Prenatal and childhood arsenic exposure were positively associated with 8-OHdG at 9 years which in turn was inversely associated with sjTRECs at 9 years. However, adjustment with 8-OHdG did not change the estimates of the association of U-As with sjTRECs reflecting little contribution from 8-OHdG-induced oxidative stress. Our findings suggest that chronic arsenic exposure from early life can result in TL attrition and lower production of naïve T cells potentially leading to immunosenescence and immunodeficiency. [ABSTRACT FROM AUTHOR]

Acrylonitrile is a colorless volatile liquid mostly present in tobacco smoke. Acrylonitrile exposure has shown to increase oxidative stress in animal studies; however, there was no previous research in human epidemiology. In this study, 853 subjects were recruited from a cohort of Taiwanese adolescents and young adults to investigate the association between urinary concentrations of the acrylonitrile metabolite N-acetyl-S-(2-cyanoethyl)-L-cysteine (CEMA), the oxidative stress product 8-hydroxydeoxyguanosine (8-OHdG) and cardiovascular disease (CVD) risk factors. The geometric mean (SD) of CEMA and 8-OHdG concentrations were 4.67 (8.61) μg/L and 2.97 (2.14) μg/L, respectively. 10% elevated in CEMA (μg/L) was positively correlated with the change of 8-OHdG levels (μg/L) (β = 0.325, SE = 0.105, P  = 0.002) in multiple linear regression analyses. The urinary CEMA was not related to other CVD risk factors. In subpopulation analyses, the association between CEMA and 8-OHdG was evident in all genders, adolescents, homeostasis model assessment of insulin resistance score ≥0.89, and environmental tobacco smokers. In this study, we observed that higher levels of CEMA levels were correlated with increased levels of 8-OHdG in this cohort. Future research on exposure to acrylonitrile and oxidative stress was warranted. [ABSTRACT FROM AUTHOR]

Riboswitches form an abundant class of cis-regulatory RNA elements that mediate gene expression by binding a small metabolite. For synthetic biology applications, they are becoming cheap and accessible systems for selectively triggering transcription or translation of downstream genes. Many riboswitches are kinetically controlled, hence knowledge of their co-transcriptional mechanisms is essential. We present here an efficient implementation for analyzing co-transcriptional RNA-ligand interaction dynamics. This approach allows for the first time to model concentration-dependent metabolite binding/unbinding kinetics. We exemplify this novel approach by means of the recently studied I-A 2 ′ -deoxyguanosine ( 2 ′ dG ) -sensing riboswitch from Mesoplasma florum . [ABSTRACT FROM AUTHOR]

Following the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, a number of evacuees were forced to live in temporary housing and suffered mental and physical stress. However, few reports have used objective or quantitative indicators to determine the evacuee's level of stress. The aim of the present study was to serially estimate the mental and physical stress of the evacuees from 2013 to 2015 by using the oxidative stress marker, urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG). A total of 773 evacuees from Namie town in Fukushima prefecture participated in the study. In the first year, 486 evacuees participated (age, 62.8±18.2 years; male/female, 217/269). Of these, 127 continually participated in the study for 3 years (age, 69.5±13.5 years; males/female 52/75) and 18.1% had no chronic disease after the first year. Urine samples were collected once per year. Urinary 8-OHdG was measured using immunochromatography and corrected by the concentration of urinary creatinine. For all the participants examined each year, mean values of urinary 8-OHdG significantly increased over time. For the 127 continual participants, mean values of urinary 8-OHdG were significantly higher in 2014 and 2015 than those in 2013. Age, gender and presence of chronic disease did not significantly influence the 8-OHdG values, suggesting that the stress level of the evacuees was not associated with these factors. The stress level of the individuals increased with the length of time spent living in the temporary housing. The evacuees in radiation disasters have different stressors from other natural disasters, which may accelerate mental and physical stress. [ABSTRACT FROM AUTHOR]

Purpose: In this study, we aimed to explain the role of oxidative stress in women with overactive bladder (OAB) by investigating the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, and malondialdehyde (MDA), an indicator of lipid peroxidation. Materials and Methods: A total of 90 women were included in the study: 45 female patients diagnosed with OAB at Hopa State Hospital Urology Polyclinic and 45 healthy women without any metabolic or neurologic disease. Levels of MDA and 8-OHdG were measured in 24-hour urine samples for all subjects. Results: Urinary levels of MDA and 8-OHdG were significantly higher in the OAB group than in the control group (p<0.001). A significant positive correlation (p<0.001) was found between the measurements of 8-OHdG and MDA. Conclusions: Oxidative stress may be important in the pathophysiology of OAB, because levels of 8-OHdG and MDA are increased. Increased levels of 8-OHdG may be due to damaged nuclear and mitochondrial DNA as a result of oxidative attacks caused by free radicals. Nevertheless, further randomized and prospective studies with larger patient populations are needed. [ABSTRACT FROM AUTHOR]

Background: Oxidative stress has been associated with cervical cancer. Our aim was to examine lipid peroxidation and the extent of oxidative stress in women diagnosed with different stages of cervical cancer in order to evaluate its potential role in the evolution of cancer. Methods: We measured the concentration of thiobarbituric acid reactive substances, activities of antioxidative enzymes and 8-hydroxy-2-deoxyguanosine in 153 subjects. Enzymatic activity as well as TBARS concentration were measured spectrophotometrically, while 8-OHdG was determined by gas chromatography-mass spectrometry. PPatients were categorized: group II H-SIL; group III FIGO la-lb and group IV FIGO lla-IV. Results: Our results showed highly significant increase in the level of lipid peroxidation in group IV when compared to the control group, group II and group III (p<0.001). Activity of superoxide dismutase was also significantly higher in group IV when compared to control group (p<0.01), group II (p<0.01) and group III (p<0.05). Activity of catalase was also significantly higher in group IV when compared to control group (p<0.005), group II (p<0.005) and group III (p<0.05). Activity of glutathione-S-transferase was also significantly higher in group IV when compared to control group (p<0.05), group II (p<0.05) and group III (p<0.05). Activities of glutathione peroxidase and glutathione reductase showed no significant differences among the groups. Level of 8-OHdG was significantly higher in group IV than in the other groups (p<0.01). Conclusions: It can be concluded that oxidative stress is possibly involved in the pathogenesis of cervical cancer, demonstrated by increased lipid peroxidation and an altered antioxidant defense system and higher levels of 8-OHdG. [ABSTRACT FROM AUTHOR]

We report on the first synthesis of a “protected” 5′-dimethoxytrityl-N-isobutyryl-2′-deoxyguanosine(dG), 3′-[(2-cyanoethyl)-2-(methacryloyloxy)propyl]-monophosphate monomer through a modified phosphoramidite coupling method. Here, 2-hydroxylpropyl methacrylate (HPMA) was coupled to a protected 5′-dimethoxytrityl-N-isobutyryl-2′-deoxyguanosine, 3′-[(2-cyanoethyl)-(N,N-diisopropyl)]-phosphoramidite. Subsequent reversible addition fragmentation chain transfer (RAFT) polymerisation of the protected monomer, followed by deprotection, produced poly[2-(deoxyguanosine-3′-phospho)propyl methacrylate] (poly(dG-P-PMA)). In situ1H nuclear magnetic resonance spectroscopy showed the polymerisation kinetics were consistent with RAFT with dispersity indices (Đ's) ＜1.2. Circular dichroism showed that the isolated deprotected deoxyguanosine rich oligomers formed stacked G-quartets in both Li+ and K+ ion solutions. These structures were further investigated with confocal fluorescence microscopy. [ABSTRACT FROM AUTHOR]

Objectives We assessed relationships between indoor black carbon (BC) exposure and urinary oxidative stress biomarkers, 8-hydroxy-2′-deoxyguanosine (8-OHdG) and malondialdehyde (MDA), in participants with chronic obstructive pulmonary disease (COPD). Methods Eighty-two participants completed in-home air sampling for one week prior to providing urine samples up to four times in a year. Weekly indoor and daily outdoor concentrations were used to estimate indoor daily lags and moving averages. There were no reported in-home BC sources, thus indoor levels closely represented outdoor BC infiltration. Mixed effects regression models with a random intercept for each participant were used to assess relationships between indoor BC and 8-OHdG and MDA, adjusting for age, race, BMI, diabetes, heart disease, season, time of urine collection, urine creatinine, and outdoor humidity and temperature. Results There were positive effects of BC on 8-OHdG and MDA, with the greatest effect the day before urine collection (6.9% increase; 95% CI 0.9–13.3%, per interquartile range: 0.22 μg/m 3 ) for 8-OHdG and 1 to 4 days before collection (8.3% increase; 95% CI 0.03–17.3% per IQR) for MDA. Results were similar in models adjusting for PM 2.5 not associated with BC and NO 2 (10.4% increase, 95% CI: 3.5–17.9 for 8-OHdG; 8.1% increase, 95% CI: −1.1–18.1 for MDA). Effects on 8-OHdG were greater in obese participants. Conclusions We found positive associations between BC exposure and 8-OHdG and MDA, in which associations with 8-OHdG were stronger in obese participants. These results suggest that exposure to low levels of traffic-related pollution results in lipid peroxidation and oxidative DNA damage in individuals with COPD. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the impact of the competitive phase on physiological and metabolic indices and selected markers of skeletal muscle damage in male volleyball players. The study group consisted of 24 young male volleyball players. During the study, participants underwent two series of measurements, before and after the competitive phase of the annual training cycle. In both study terms, players performed an incremental treadmill running test to determine their ventilatory threshold and maximal oxygen uptake. Venous and capillary blood samples were taken for biochemical analysis. There was no significant difference in the physical fitness level, values of biochemical variables and the level of antioxidant status in the surveyed athletes between the two study terms. Significant changes within skeletal muscle damage markers were observed between the beginning and the end of the competitive period: an increase in the concentration of cellular DNA damage products (8-hydroxy-2′-deoxyguanosine; p < 0.0001) and a decrease in muscle activity of creatine kinase (p<0.05). In spite of the increment in cell damage markers, the unaffected level of physiological and biochemical markers may indicate that the experienced cell destruction did not negatively affect the level of physical fitness. When designing the annual training plan, coaches and athletes need to take into consideration that temporary physiological states – oxidative stress and inflammation – may be required to attain training adaptation. [ABSTRACT FROM AUTHOR]

In this work, an innovative magnetic aptamer adsorbent (Fe 3 O 4 -aptamer MNPs) was synthesized for the selective extraction of 8-hydroxy-2′-deoxyguanosine (8-OHdG). Amino-functionalized-Fe 3 O 4 was crosslinked with 8-OHdG aptamer by glutaraldehyde and fixed into a steel stainless tube as the sorbent of magnetic solid phase extraction (MSPE). After selective extraction by the aptamer adsorbent, the adsorbed 8-OHdG was desorbed dynamically and online analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS). The synthesized sorbent presented outstanding features, including specific selectivity, high enrichment capacity, stability and biocompatibility. Moreover, this proposed MSPE-HPLC-MS can achieve adsorption and desorption operation integration, greatly simplify the analysis process and reduce human errors. When compared with offline MSPE, a sensitivity enhancement of 800 times was obtained for the online method. Some experimental parameters such as the amount of the sorbent, sample flow rate and sample volume, were optimized systematically. Under the optimal conditions, low limit of detection (0.01 ng mL −1 , S/N = 3), limit of quantity (0.03 ng mL −1 , S/N = 10) and wide linear range with a satisfactory correlation coefficient (R 2  ≥ 0.9992) were obtained. And the recoveries of 8-OHdG in the urine samples varied from 82% to 116%. All these results revealed that the method is simple, rapid, selective, sensitive and automated, and it could be expected to become a potential approach for the selective determination of trace 8-OHdG in complex urinary samples. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is a widely used additive in the plastic industry and has been reported to have genotoxicity. A hypothesis that BPA may enhance breast cancer risk through the formation of its metabolic intermediate or DNA adduct has been proposed. In this study, breast cancer cell MCF-7 was cultured and the cellular DNA was extracted from the cells. The adducts of bisphenol A 3,4-quinone (BPAQ) with 2′-deoxyguanosine (dG), calf thymus DNA and MCF-7 cell DNA were investigated. DNA adducts were characterized by using electrospray ionization Orbitrap high-resolution mass spectrometry and tandem mass spectrometry. The BPA-DNA adducts of BPAQ with dG, calf thymus and MCF-7 cell DNA were identified as 3-hydroxy-bisphenol A-N7-guanine (3-OH-BPA-N7Gua). The MS/MS fragmentation pathway of 3-OH-BPA-N7Gua was proposed based on obtained accurate mass data. BPA quinone metabolites can react with MCF-7 cell DNA in vitro . The findings provide evidence that BPA might covalently bind to DNA in MCF-7 cells mediated by quinone metabolites, which may increase our understanding of health risk associated with BPA exposure. [ABSTRACT FROM AUTHOR]

In the present study, the repair activity of trans-resveratrol toward 2'-deoxyguanosine (dGuo) radicals in polar and nonpolar solvents was studied using density functional theory. The hydrogen transfer/proton coupled electron transfer and single electron transfer (SET) mechanisms between trans-resveratrol and dGuo-radicals were considered. Taking into consideration the molar fraction of neutral trans-resveratrol (ROH) and anionic trans-resveratrol (RO-), the overall rate constants for repairing dGuo-radicals by trans-resveratrol are 9.94 × 108 and 2.01 × 109 dm3 mol-1 s-1 in polar and nonpolar solvents, respectively, and the overall rate constant of repairing cation radical (dGuo•+) by trans-resveratrol via an SET mechanism is 7.17 × 109 dm3 mol-1 s-1. The repair activity of RO- toward dGuo-radicals is better than that of ROH, but the repair activity of ROH toward dGuo•+ is better than that of RO-. Unfortunately, neither ROH nor RO- can repair the 2'-deoxyribose radicals of dGuo. It can therefore be concluded that trans-resveratrol is an effective antioxidant for repairing base radicals of dGuo and dGuo•+. The study can help us understand the repair activity of trans-resveratrol toward dGuo radicals. [ABSTRACT FROM AUTHOR]

Study Question: Can a discriminant threshold be determined for human sperm DNA oxidation?Summary Answer: A discriminant threshold was found with 65.8% of 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive sperm cells and a mean intensity of fluorescence (MIF) of 552 arbitrary units.What Is Known Already: Oxidative stress is known to interfere with sperm quality and fertilizing capacity. However, current practice does not include the routine determination of oxidative DNA damage in spermatozoa; optimized consensus protocols are lacking and no thresholds of normality have been established.Study Design, Size, Duration: Intra- and inter-method comparisons between four protocols (I-IV) were conducted to determine the most relevant and efficient means of assessing human sperm 8-OHdG content. Tests of assay repeatability, specificity, sensitivity and stability were performed to validate an optimized methodology for routine diagnostic use.Participants/materials, Setting, Methods: This prospective study compared three immuno-detection methods including immunocytochemistry, fluorescence microscopy and flow cytometry. Sperm DNA oxidation for 80 patients was determined relative to semen parameters and clinical conditions, using the selected immuno-detection protocol in comparison with a commercial kit. These patients (age 35 ± 1 years: mean ± SEM) presented with normozoospermic (n = 40) or altered parameters (necro- or/and astheno- or/and teratozoospermia or/and leukocytospermia).Main Results and the Role Of Chance: Significant positive Pearson and Spearman correlations were determined for 8-OHdG values and sperm parameters using protocol III. A notable high and positive correlation was revealed for MIF with BMI and leukocyte concentration. Protocol III was the most discriminating method regarding assay repeatability, specificity, sensitivity, stability and reliability for sperm parameter alterations, in particular leukocytospermia according to parametric or non-parametric tests, effect-size determinations and factorial analysis such as principal component analysis and factor discriminant analysis. Of interest is that 39% of the subjects with 'pathological' sperm DNA oxidation values were normozoospermic.Limitations, Reasons For Caution: The oligozoospermic population was not evaluated in this study because insufficient material was available to carry out the comparisons. However, spermatozoa concentration was taken into account in the statistical analysis.Wider Implications Of the Findings: Our study is the first validation of a protocol to determine a discriminant threshold for human sperm DNA oxidation. The protocol's detection accuracy for 8-OHdG human sperm DNA residues, stability over time, and relationship to human sperm quality were demonstrated. The assay should find application in the diagnosis of male factor infertility associated with oxidative stress.Study Funding/competing Interest(s): This work was funded by institutional grants from the CNRS, INSERM and Université Clermont Auvergne (to J.R.D.) and by Clermont-Ferrand Hospital-CECOS research funds (to L.J. and F.B.). P.G., A.M., R.J.A. and J.D. are, respectively, CEO, scientific director and scientific advisors of a US-based biotech company (Celloxess, Princeton, NJ, USA) involved in preventative medicine with a focus on the generation of antioxidant oral supplements. [ABSTRACT FROM AUTHOR]

Oxidative stress may cause a wide variety of free radical reactions to produce deleterious modifications in membranes, proteins, enzymes, and DNA. Reactive Oxygen Species (ROS) generated by myeloperoxidase (MPO) can induce lipid peroxidation and also play an important role in the generation of reactive chlorinating and brominating species. As the universal biomarkers, chemical, and immunochemical approach on oxidatively modified and halogenated tyrosines has been carried out. As amido-type adduct biomarkers, chemical, and immunochemical evaluation of hexanoyl- and propanoyl-lysines, hexanoyl- and propanoyl-dopamines and phospholipids were prepared and developed for application of evaluation of novel antioxidative functional food factors. We have also involved in application of oxidatively modified DNAs such as 8-hydroxy- and 8-halogenated deoxyguanosines as the useful biomarkers for age-related diseases using both in vitro and in vivo systems. Application of these oxidative stress biomarkers for novel type of functional food development and recent approach for development of novel evaluation systems are also discussed. [ABSTRACT FROM AUTHOR]

Introduction: Homocysteine (Hcy) tissue accumulation occurs in a metabolic disease characterized biochemically by cystathionine ß-synthase (CBS) deficiency and clinically by mental retardation, vascular problems, and skeletal abnormalities. Previous studies indicate the occurrence of DNA damage secondary to hyperhomocysteinemia and it was observed that DNA damage occurs in leukocytes from CBS-deficient patients. This study aimed to investigate whether an oxidative mechanism could be involved in DNA damage previously found and investigated the in vitro effect of N-acety-L-cysteine (NAC) on DNA damage caused by high Hcy levels. Methods: We evaluated a biomarker of oxidative DNA damage in the urine of CBS-deficient patients, as well as the in vitro effect of NAC on DNA damage caused by high levels of Hcy. Moreover, a biomarker of lipid oxidative damage was also measured in urine of CBS deficient patients. Results: There was an increase in parameters of DNA (8-oxo-7,8-dihydro-2'- deoxyguanosine) and lipid (15-F2t-isoprostanes levels) oxidative damage in CBS-deficient patients when compared to controls. In addition, a significant positive correlation was found between 15-F2t-isoprostanes levels and total Hcy concentrations. Besides, an in vitro protective effect of NAC at concentrations of 1 and 5 mM was observed on DNA damage caused by Hcy 50 µM and 200 µM. Additionally, we showed a decrease in sulfhydryl content in plasma from CBS-deficient patients when compared to controls. Discussion: These results demonstrated that DNA damage occurs by an oxidative mechanism in CBS deficiency together with lipid oxidative damage, highlighting the NAC beneficial action upon DNA oxidative process, contributing with a new treatment perspective of the patients affected by classic homocystinuria. [ABSTRACT FROM AUTHOR]

Objective: Impairment of the lipid metabolism could affect the periodontal disease; increased oxidative stress may have a role in this relationship. The aim of the present study was to evaluate the role of menopause in the relationship between hyperlipidemia and periodontal disease via oxidative stress markers in saliva.Materials and Methods: Sixty-seven women were enrolled in the study and divided into four groups as systemically healthy and premenopause (C) (n = 18), hyperlipidemia and premenopause (H) (n = 16), systemically healthy and postmenopause (M) (n = 17), and hyperlipidemia and postmenopause (MH) (n = 16). Sociodemographics, periodontal and metabolic parameters, and saliva oxidative markers (myeloperoxidase [MPO] and 8-hydroxy-2'-deoxyguanosine [8-OHdG]) were evaluated.Results: Menopause and/or hyperlipidemia were associated with an increase in all evaluated periodontal parameters. Saliva 8-OHdG and MPO levels were higher in menopausal groups (M and MH). Multivariate linear regression analyses revealed that hyperlipidemia was related to an increase in periodontal parameters. Salivary oxidative stress markers and periodontal parameters were also positively associated with menopause and hyperlipidemia.Conclusion: Saliva 8-OHdG and MPO levels may indicate that the relationship between periodontal disease and hyperlipidemia is aggravated by menopause. [ABSTRACT FROM AUTHOR]

In the present work a highly sensitive and selective aptasensor was developed for the determination of 8-hydroxy-2′-deoxyguanosine (8-OH-dG) based on the hybridization chain reaction (HCR) signal amplification. It was observed that the aptamer of 8-OH-dG could hybridize with the capture DNA immobilized on the gold electrode with a sticky tail left, which initiated the HCR and led to the formation of extended dsDNA structure on the electrode surface. Then the electroactive species ([Ru(NH 3 ) 6 ] 3+ , RuHex) intercalated into the dsDNA grooves to generate the amplified signal. However, in the presence of 8-OH-dG, the aptamer containing G-rich nucleic acid sequences would be induced to form a G-quadruplex structure, which made it impossible to continue the HCR. So the detection signal will significantly decrease. Under the optimal conditions, the peak current of RuHex was linear with the logarithm of 8-OH-dG concentration in the range from 10 pM to 100 μM with the detection limit of 2.5 pM. By integrating the merits of enzyme-free amplification power of the HCR and the inherent high sensitivity of the electrochemical technique, the prepared aptasensor not only showed high sensitivity for the detection of 8-OH-dG, but also exhibited good selectivity against to the uric acid, an important interferent in the urine sample. Particularly, the aptasensor was applied to detect 8-OH-dG in urine samples with satisfactory results. [ABSTRACT FROM AUTHOR]

DNA replication in cells is performed in the presence of four dNTPs and four rNTPs. In this study, we re-evaluated the fidelity of DNA polymerases using the general misincorporation frequency consisting of three incorrect dNTPs and four rNTPs but not using the traditional special misincorporation frequency with only the three incorrect dNTPs. We analyzed both the general and special misincorporation frequencies of nucleotide incorporation opposite dG, rG, or 8-oxoG by Pseudomonas aeruginosa phage 1 (PaP1) DNA polymerase Gp90 or Sulfolobus solfataricus DNA polymerase Dpo4. Both misincorporation frequencies of other DNA polymerases published were also summarized and analyzed. The general misincorporation frequency is obviously higher than the special misincorporation frequency for many DNA polymerases, indicating the real fidelity of a DNA polymerase should be evaluated using the general misincorporation frequency. [ABSTRACT FROM AUTHOR]

Methylglyoxal (MG) is a highly reactive electrophile produced endogenously as a byproduct of glucose metabolism and protein catabolism and exogenously as a food contaminant. MG reacts spontaneously with proteins, lipids, and nucleic acids to form advanced glycation end products (AGEs), modifying or inhibiting their function. Protein AGEs are associated with pathological complications of diabetes, cancer, and neurodegenerative diseases, while the physiological impact of DNA, RNA, and lipid AGE formation is less well explored. Conflicting reports in the literature on the biologically significant DNA-AGE product distribution and mechanisms of formation prompted a re-examination of the reaction products of MG with dG, oligonucleotides, and plasmid DNA under varying conditions of MG:dG stoichiometry, pH, and reaction time. Major products identified using sequential mass fragmentation and authentic standards were N²-(1-carboxyethyl)-2'-dG (CEdG), N²-(1-carboxyethyl)-7-1-hydroxy-2-oxopropyl-dG (MG-CEdG), and 1,N²-(1,2-dihydroxy-2-methyl)ethano-2'-dG (cMG-dG). CEdG and MG-CEdG were observed in all DNA substrates, although cMG-dG was not detected to any significant extent in oligomeric or polymeric DNA. Product analyses of reactions under conditions of diminished water activity as well as results from H218O labeling indicated that MG hydration equilibria plays an important role in controlling product distribution. In contrast to previous reports, our data support independent mechanisms of formation of CEdG and cMG-dG, with the latter kinetic product undergoing reversible formation under physiological conditions. [ABSTRACT FROM AUTHOR]

Endogenous and dietary nitrite produces reactive nitrogen species (RNS) that react with DNA causing mutations. The nitrosation of 2′-deoxyguanosine (dGuo) and DNA with nitrite was studied under different conditions, and the reaction and degradation products identified and analysed by HPLC-DAD-MS. Nitrosative deamination of dGuo produced xanthine along with 2′-deoxyxanthosine whereas DNA afforded xanthine. Formation of xanthine increased with nitrite concentration and in low pH such as that of stomach. Xanthine was measured as a marker of nitrosation of dGuo and DNA, and it was subsequently used to study the antinitrosating activity of β-carboline alkaloids, and selected antioxidants. Food-occurring tetrahydro-β-carbolines (THβCs) decreased nitrosative deamination of dGuo and DNA under conditions simulating the stomach. Antinitrosating activity was also evidenced for flavonoids (catechin, quercetin) and indole (melatonin) antioxidants. Among THβCs the most active antinitrosating compounds were 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acids (THβC-3-COOHs) that reacted with nitrite to give N -nitroso derivatives as main products along with 3,4-dihydro-β-carboline-3-carboxylic acids and aromatic β-carbolines (norharman and harman). Antinitrosating activity of THβCs correlated well with the formation of N -nitroso-THβC-3-COOHs. These N -nitroso derivatives were stable at pH 7 but degraded in acid conditions affording nitrosating species. [ABSTRACT FROM AUTHOR]

Purpose: Although previous studies have investigated oxidative stress biomarkers in association with depression in non-stroke subjects, the association between oxidative deoxyribonucleic acid damage and post-stroke depression (PSD) remains unelucidated. Patients and methods: Two hundred forty-one first-ever ischemic stroke patients were consecutively recruited within the first 24 h of stroke onset and were followed up at 1 month. Serum 8-hydroxy-2'-deoxyguanosine (8-OHdG) and catalase (CAT) levels were measured within 24 h of admission using a commercially available enzyme-linked immunosorbent assay. The 17-item Hamilton Depression Scale was used to evaluate depressive symptoms. Diagnosis of PSD was made in line with the Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria for depression. Results: Serum levels of 8-OHdG (P < 0.001) and CAT (P=0.025) increased in depressed patients at admission. A positive correlation was found between the 8-OHdG and CAT levels in both the total stroke patients (r=0.320, P < 0.001) and the depressed patients (r=0.300, P=0.012). The 8-OHdG levels were positively correlated with the 17-item Hamilton Depression Scale scores (r=0.129, P=0.046) in depressed patients. Multivariate analyses found that 8-OHdG levels ≥200.0 ng/L were independently associated with PSD (odds ratio, 7.477; 95% CI, 3.342-16.289, P < 0.001) after adjusting for possible relevant confounders. Conclusion: Higher serum 8-OHdG levels at admission were found to be correlated with PSD 1 month after stroke. [ABSTRACT FROM AUTHOR]

The purpose of the study was to evaluate the effect nitric oxide (NOx) pollution had on maternal serum 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-OHdG) levels and neonatal outcomes in pregnant women living in Durban, South Africa (SA). Women, in their third trimester with singleton pregnancies, were recruited from the heavily industrialised south (n = 225) and less industrialised north (n = 152). Biomarker levels of serum 8-OHdG concentrations were analysed, and the women were genotyped for glutathione-S-transferases pi 1 (GSTP1) and glutathione-S-transferases mu 1 (GSTM1) polymorphisms. The level of NOx pollution in the two regions was determined by using land use regression modelling. The serum 8-OHdG was shown to correlate significantly with NOx levels; this relationship was strengthened in the south (p < 0.05). This relationship was still observed after adjusting for maternal characteristics. GSTP1 was significantly associated with the south region, where the variant (AG+GG) genotype was associated with increased 8-OHdG levels as a result of NOx exposure (p < 0.05). GSTM1 null genotype was associated with a positive correlation between NOx and 8-OHdG levels (p < 0.05). NOx levels were found marginally to reduce gestational age (p < 0.05) with mothers carrying male neonates. Variant GSTP1 and living in the north were factors that contributed to gestational age reduction (p < 0.05). Our study demonstrated that NOx exposure resulted in increased 8-OHdG levels in pregnant women living in Durban, SA, which led to gestational age reduction. The GSTP1 variant increased susceptibility of individuals to harmful effects of NOx. [ABSTRACT FROM AUTHOR]

Pancreatic cancer has a poor prognosis and is an important public health problem for developing countries. Oxidative stress plays an important role in cancer initiation, progression, proliferation, invasion, angiogenesis and metastasis. For this reason, one of the important strategic targets of new cancer therapeutics is to drive cancer cells into apoptosis through oxidative stress. In nuclear and mitochondrial DNA, 8-hydroxy-2′-deoxyguanosine and gamma-H2AX (γ-H2AX) are used as important oxidative stress biomarkers. Fusaric acid (FA) is a mycotoxin that mediates toxicity produced by Fusarium species and exhibits anticancer effects in various cancers via inducing apoptosis, cell cycle arrest, or other cellular mechanisms. The aim of this study was to determine the effects of fusaric acid on cytotoxic and oxidative damage in MIA PaCa-2 and PANC-1 cell lines. In this context, dose and time dependent cytotoxic effect of fusaric acid was determined by XTT method, mRNA expression levels of genes related to DNA repair were determined by RT-PCR, and its effect on 8-hydroxy-2′-deoxyguanosine and γ-H2AX levels was revealed by ELISA assay. According to XTT results, fusaric acid inhibits cell proliferation in MIA PaCa-2 and Panc-1 cells in a dose- and time-dependent manner. IC 50 doses were determined as 187.74 μM at 48 h in MIA PaCa-2 cells and 134.83 μM at 48 h in PANC-1 cells, respectively. γ-H2AX and 8-OHdG changes were not found significant in pancreatic cancer cells. The mRNA expression levels of DNA repair-related genes NEIL1, OGG1, XRCC and Apex-1 change with exposure to fusaric acid. This study contributes to the therapeutic approaches to be developed for pancreatic cancer and demonstrates the potential of fusaric acid as an anticancer agent. [Display omitted] • Fusaric acid decreases cell proliferation in PANC-1 and MiaPaca-2 pancreatic cancer cells. • The expression levels of DNA repair-related genes can be regulated by fusaric acid. • Fusaric acid increases 8-OHdG and gamma H2A X levels in pancreatic cancer cells. [ABSTRACT FROM AUTHOR]