Oxidative DNA damage estimated by 8-hydroxydeoxyguanosine excretion in humans: influence of smoking, gender and body mass index

Metal and oxidative potential exposure through particle inhalation and oxidative stress biomarkers: a 2-week pilot prospective study among Parisian subway workers

OBJECTIVE

In this pilot study on subway workers, we explored the relationships between particle exposure and oxidative stress biomarkers in exhaled breath condensate (EBC) and urine to identify the most relevant biomarkers for a large-scale study in this field.

METHODS

We constructed a comprehensive occupational exposure assessment among subway workers in three distinct jobs over 10 working days, measuring daily concentrations of particulate matter (PM), their metal content and oxidative potential (OP). Individual pre- and post-shift EBC and urine samples were collected daily. Three oxidative stress biomarkers were measured in these matrices: malondialdehyde (MDA), 8-hydroxy-2'deoxyguanosine (8-OHdG) and 8-isoprostane. The association between each effect biomarker and exposure variables was estimated by multivariable multilevel mixed-effect models with and without lag times.

RESULTS

The OP was positively associated with Fe and Mn, but not associated with any effect biomarkers. Concentration changes of effect biomarkers in EBC and urine were associated with transition metals in PM (Cu and Zn) and furthermore with specific metals in EBC (Ba, Co, Cr and Mn) and in urine (Ba, Cu, Co, Mo, Ni, Ti and Zn). The direction of these associations was both metal- and time-dependent. Associations between Cu or Zn and MDAEBC generally reached statistical significance after a delayed time of 12 or 24 h after exposure. Changes in metal concentrations in EBC and urine were associated with MDA and 8-OHdG concentrations the same day.

CONCLUSION

Associations between MDA in both EBC and urine gave opposite response for subway particles containing Zn versus Cu. This diverting Zn and Cu pattern was also observed for 8-OHdG and urinary concentrations of these two metals. Overall, MDA and 8-OHdG responses were sensitive for same-day metal exposures in both matrices. We recommend MDA and 8-OHdG in large field studies to account for oxidative stress originating from metals in inhaled particulate matter.

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

The Predictive Value of 8-Hydroxy-Deoxyguanosine (8-OHdG) Serum Concentrations in Irradiated Non-Small Cell Lung Carcinoma (NSCLC) Patients

Ionizing radiation is strongly linked to direct or indirect DNA damage, as with the production of reactive oxygen species (ROS), which in turn produce DNA damage products, such as 8-hydroxy-2-deoxyguanosine (8-OHdG). In this study, we aimed to investigate the formation of 8-OHdG after irradiation in patients with non-small cell cancer (NSCLC) and its use as a biomarker. Sixteen patients with squamous and thirty-six patients with non-squamous pathology were included. An enzyme-linked-immunosorbent assay (ELISA) was performed before and after radiation. A dose-dependent relationship was confirmed: 8-OHdG plasma concentrations, increased in the total of NSCLC patients and specifically with a linear correlation in non-squamous pathology; in squamous histology, after an initial increase, a significant decrease followed after 20 Gy dose of irradiation. The pretreatment total irradiated tumor volume (cm3) was positively correlated with 8-OHdG levels in patients with squamous histology. When plotting the 8-OHdG plasma concentration at a 10 Gy irradiation dose to the baseline, the AUC was 0.873 (95% CI 0.614-0.984), p < 0.0001, with an associated criterion value of >1378 as a cutoff (sensitivity 72.7%, specificity 100%). When normalizing this ratio to BSA, the associated criterion cutoff value was >708 (sensitivity of 100%, specificity 80%). Lastly, 8-OHdG levels were closely related with the development of radiation-induced toxicities.

Risk factors for early-onset lung cancer in Korea: analysis of a nationally representative population-based cohort

OBJECTIVES

We examined the associations of socioeconomic factors, health behaviors, and comorbidities with early-onset lung cancer.

METHODS

The study included 6,794,287 individuals aged 20-39 years who participated in a Korean national health check-up program from 2009 to 2012. During the follow-up period, 4,684 participants developed lung cancer. Multivariable Cox regression analysis was used to estimate the independent associations of potential risk factors with incident lung cancer.

RESULTS

Older age (multivariable hazard ratio [mHR], 1.13; 95% confidence interval [CI], 1.12 to 1.14) and female sex (mHR, 1.62; 95% CI, 1.49 to 1.75) were associated with increased lung cancer risk. Current smoking was also associated with elevated risk (<10 pack-years: mHR, 1.12; 95% CI, 1.01 to 1.24; ≥10 pack-years: mHR, 1.30; 95% CI, 1.18 to 1.45), but past smoking was not. Although mild alcohol consumption (<10 g/day) was associated with lower lung cancer risk (mHR, 0.92; 95% CI, 0.86 to 0.99), heavier alcohol consumption (≥10 g/day) was not. Higher income (highest vs. lowest quartile: mHR, 0.86; 95% CI, 0.78 to 0.94), physical activity for at least 1,500 metabolic equivalent of task-min/wk (vs. non-exercisers: mHR, 0.83; 95% CI, 0.69 to 0.99) and obesity (vs. normal weight: mHR, 0.89; 95% CI, 0.83 to 0.96) were associated with lower lung cancer risk, whereas metabolic syndrome was associated with increased risk (mHR, 1.13; 95% CI, 1.03 to 1.24).

CONCLUSIONS

In young adults, age, female sex, smoking, and metabolic syndrome were risk factors for early-onset lung cancer, while high income, physical activity, and obesity displayed protective effects.

Gender Differences in Oxidative Stress in Relation to Cancer Susceptibility and Survival

Genetic, developmental, biochemical, and environmental variables interact intricately to produce sex differences. The significance of sex differences in cancer susceptibility is being clarified by numerous studies. Epidemiological research and cancer registries have revealed over the past few years that there are definite sex variations in cancer incidence, progression, and survival. However, oxidative stress and mitochondrial dysfunction also have a significant impact on the response to treatment of neoplastic diseases. Young women may be more protected from cancer than men because most of the proteins implicated in the regulation of redox state and mitochondrial function are under the control of sexual hormones. In this review, we describe how sexual hormones control the activity of antioxidant enzymes and mitochondria, as well as how they affect several neoplastic diseases. The molecular pathways that underlie the gender-related discrepancies in cancer that have been identified may be better understood, which may lead to more effective precision medicine and vital information on treatment options for both males and females with neoplastic illnesses.

Impact of modernization on oxidative stress among indigenous populations in northern Laos

OBJECTIVES

To explore the impact of modernization on oxidative stress during a momentous health transition process, we investigated differences in oxidative stress among the indigenous populations of villages in northern Laos with different levels of modernization.

METHODS

We conducted a cross-sectional study of 380 adults in three villages with different levels of modernization. Three biomarkers related to oxidative stress were measured: urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-isoprostane concentrations (both measured by liquid chromatography-tandem mass spectrometry), and blood telomere length (measured with qPCR). We examined associations between village-level modernization and oxidative stress-related biomarkers in a multilevel analysis including a random effect and covariates.

RESULTS

The geometric means of urinary 8-OHdG and 8-isoprostane concentrations were 2.92 and 0.700 μg/g creatinine, respectively, in our study population. Higher urinary 8-OHdG concentrations and shorter telomeres were observed in participants from the more modernized villages, whereas urinary 8-isoprostane concentrations did not differ significantly among villages.

CONCLUSIONS

Our findings imply that modernization-induced changes in lifestyle may increase oxidative DNA damage. Baseline levels of oxidative lipid damage are expected to be high in the indigenous populations of northern Laos. Assessments of oxidative stress may provide valuable insights into the mechanisms of health transition in specific populations.

Association between atmospheric pollutant levels and oxidative stress in pregnant women and newborns in Urumqi

BACKGROUND

Frequent heavy air pollution occurred during the winter heating season of northern China. Particulate air pollution is a serious concern in Urumqi during heating season. Exposure to air pollution is known to increase adverse health outcomes, particularly oxidative damage. This study aimed to evaluate the impact of air pollution on oxidative damage around pregnant women and newborns in Urumqi.

METHODS

This prospective observational study enrolled pregnant women in the Fifth Affiliated Hospital of Xinjiang Medical University between January 2019 and October 2019. Pregnant women and newborns were allocated into a heating season group (January - end of April 2019, October 2019) or non-heating season group (June 2019 - end of September) according to the specific delivery time. Venous blood, urine from the women and cord blood from their newborns were collected to measure the levels of PAHs and 8-deoxyguanosine (8-OHdG), a measure of oxidative stress.

RESULTS

A total of 200 pregnant women and newborns were enrolled, with 100 pregnant women and newborns in the heating season group. Compared to the non-heating season group, the total contents of 8-OHdG in maternal urine, PAHs and 8-OHdG in maternal plasma and neonatal cord blood were higher in the heating season group (all P < 0.001). The average values for AQI, PM_2.5, PM₁₀, SO₂, NO₂, and CO were higher in the heating season group (all P < 0.001). Maternal and neonatal PAHs were correlated with 8-OHdG measurements in maternal urine (r = 0.288, P < 0.001 and r = 0.336, P < 0.001) and neonatal umbilical cord blood (r = 0.296, P < 0.001 and r = 0.252, P < 0.001). There was also a positive relationship between PAHs, 8-OHdG levels in pregnant women and their newborns and proximate air pollutant concentrations (all P < 0.05). Based on the results of multiple linear regression analysis, it was found that air pollutants(PM₁₀, 0₃) had a great influence on the level of 8-OHdG in neonatal cord blood, and the contribution rate was high(R² = 0.320). Based on the epidemiological questionnaire, a multiple linear regression model was established(R² = 0.496). We found that 8-OHdG levels in neonatal umbilical cord blood were mainly affected by two aspects: (1) Biological samples collected during heating had higher levels of 8-OHdG in neonatal umbilical cord blood. (2) Study may suggest that in neonates, males are more sensitive to oxidative damage.

CONCLUSION

Particulate air pollution may increase PAHs exposure and oxidative DNA damage in pregnant women and newborns.

Performance of urinary biomarkers in differentiating dysfunctional voiding in women with overactive bladder syndrome: a prospective pilot study

PURPOSE

Dysfunctional voiding (DV) in women is a common disorder that causes bladder outlet obstruction (BOO) and may aggravate overactive bladder (OAB) symptoms. The diagnosis of DV relies on clinical alertness and videourodynamic study (VUDS). In this pilot study, we aimed to explore the diagnostic potential of urinary biomarkers in women with DV.

METHODS

Women who visited our institute for the management of OAB were enrolled in this prospective study. Urine samples were collected before treatment and urinary proteins were quantified using enzyme-linked immunosorbent assay (ELISA) kits. Patients with DV and patients with normal tracings were included in the study and control group, respectively. The patients with DV were further divided into two subgroups: those with and those without detrusor overactivity (DO). VUDS parameters and urinary protein levels were compared between each subgroup.

RESULTS

A total of 67 women were enrolled. There were 47 patients with VUDS-diagnosed DV and 20 patients in the control group. Urinary 8-OHdG level (32.65 vs. 15.59, p < 0.001) and urinary TNF-α level (1.43 vs. 0.83, p = 0.031) were significantly higher in the DV group, and urinary IL-2 level (0.29 vs. 0.83, p < 0.001) was significantly lower in the DV group. Among the DV patients, urinary PGE2 level was higher in the DO group (240.4 vs 149.6, p = 0.049).

CONCLUSIONS

In women with DV, urinary 8-OHdG level is elevated compared to women with normal VUDS. Urinary PGE2 level is elevated in patients with DV and DO. These finding suggests increased reactive-oxidative stress response and detrusor hyperactivity in DV patients. Urinary biomarkers can serve as potential non-invasive diagnostic tools in women with OAB.

Urinary Oxidative Damage Markers and Their Association with Obesity-Related Metabolic Risk Factors

Oxidative damage and inflammation are possible mechanisms linking obesity to diabetes and related complications. This study investigates the levels of oxidative damage markers in the urine of community free-living subjects with increased prevalence of obesity. Methods: Participants were assessed regarding clinical, anthropometric, and physical activity data at baseline and at 6 months. Blood and urine samples were taken for the measurements of oxidative markers in urine ((glutathione (GSH), thiobarbituric acid reactive substances (TBARS), pteridine, 8-isoprostane and 8-hydroxy-2′-deoxyguanosine (8-OH-dG)), metabolic and inflammatory markers, and related biochemical variables in the blood. Univariate and multiple regression analyses were used to assess the association between oxidative markers and other clinical prognostic indicators. Results: Overall, 168 participants with a complete 6-month follow-up with a mean (±SD) age of 41 ± 12 (119 (71%) females) were included in the study. In multiple regression analysis, log-transformed urinary pteridine levels were significantly correlated with log-transformed urinary GSH, 8-isoprostane, and TBARS after adjusting for urinary creatinine at both baseline and follow-up. Significant correlations were also found between oxidative damage markers and cardiovascular disease risk factors, including systolic blood pressure, HbA1c, plasma glucose, us-C-reactive proteins, total cholesterol, and HDL. Higher TBARS levels were found in males and diabetic subjects, with lower GSH in diabetic hypertensive and obese subjects, but the latter result did not reach statistical significance. We found nonsignificantly higher TBARS, 8-isoprostane, and pteridine levels in smokers compared to those in nonsmokers. All measured urinary oxidative damage markers levels were higher in obese subjects compared with normal-weight subjects, but results did not reach statistical significance. Conclusion: we found significant associations between urinary oxidative damage and metabolic risk factors, and higher levels of urinary oxidative damage markers in diabetic, hypertensive, smoker, and male subjects.

Oxidative RNA Damage in the Pathogenesis and Treatment of Type 2 Diabetes

Excessive production of free radicals can induce cellular damage, which is associated with many diseases. RNA is more susceptible to oxidative damage than DNA due to its single-stranded structure, and lack of protective proteins. Yet, oxidative damage to RNAs received little attention. Accumulating evidence reveals that oxidized RNAs may be dysfunctional and play fundamental role in the occurrence and development of type 2 diabetes (T2D) and its complications. Oxidized guanine nucleoside, 8-oxo-7, 8-dihydroguanine (8-oxoGuo) is a biomarker of RNA oxidation that could be associated with prognosis in patients with T2D. Nowadays, some clinical trials used antioxidants for the treatment of T2D, though the pharmacological effects remained unclear. In this review, we overview the cellular handling mechanisms and the consequences of the oxidative RNA damage for the better understanding of pathogenesis of T2D and may provide new insights to better therapeutic strategy.

Health consequences of disinfection against SARS-CoV-2: Exploring oxidative stress damage using a biomonitoring approach

Individuals who get involved in the disinfection of public settings using sodium hypochlorite might suffer adverse health effects. However, scarce information is available on the potential oxidative stress damage caused at low concentrations typically used for disinfection. We aimed to assess whether exposure to sodium hypochlorite during the COVID-19 pandemic causes oxidative stress damage in workers engaged in disinfection tasks. 75 operators engaged in the disinfection of public places were recruited as the case group, and 60 individuals who were not exposed to disinfectant were chosen as the control group. Spot urine samples were collected before (BE) and after exposure (AE) to disinfectants in the case group. Likewise, controls provided two spot urine samples in the same way as the case group. Urinary malondialdehyde (MDA) levels were quantified by forming thiobarbituric acid reactive substances in the urine. In addition, the concentration of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the urine was determined using an ELISA kit. Results showed significant differences in the urinary levels of oxidative stress markers, where median 8-OHdG (AE case: 3.84 ± 2.89 μg/g creatinine vs AE control 2.54 ± 1.21 μg/g creatinine) and MDA (AE case: 169 ± 89 μg/g creatinine vs AE control 121 ± 47 μg/g creatinine) levels in case group AE samples were 1.55 and 1.35-times higher than the control group AE samples (P < 0.05), respectively. Besides, urinary levels of oxidative stress markers in AE samples of the case group were significantly higher than in BE samples (8-OHdG BE 3.40 ± 1.95 μg/g creatinine, MDA BE 136 ± 51.3 μg/g creatinine, P < 0.05). Our results indicated that exposure to even low levels of sodium hypochlorite used in disinfection practices might cause oxidative stress related damage. With this in mind, implementing robust protective measures, such as specific respirators, is crucial to reduce the health burdens of exposure to disinfectants.

8-oxoguanine and 8-oxodeoxyguanosine Biomarkers of Oxidative DNA Damage: A Review on HPLC-ECD Determination

Reactive oxygen species (ROS) are continuously produced in living cells due to metabolic and biochemical reactions and due to exposure to physical, chemical and biological agents. Excessive ROS cause oxidative stress and lead to oxidative DNA damage. Within ROS-mediated DNA lesions, 8-oxoguanine (8-oxoG) and its nucleotide 8-oxo-2'-deoxyguanosine (8-oxodG)-the guanine and deoxyguanosine oxidation products, respectively, are regarded as the most significant biomarkers for oxidative DNA damage. The quantification of 8-oxoG and 8-oxodG in urine, blood, tissue and saliva is essential, being employed to determine the overall effects of oxidative stress and to assess the risk, diagnose, and evaluate the treatment of autoimmune, inflammatory, neurodegenerative and cardiovascular diseases, diabetes, cancer and other age-related diseases. High-performance liquid chromatography with electrochemical detection (HPLC-ECD) is largely employed for 8-oxoG and 8-oxodG determination in biological samples due to its high selectivity and sensitivity, down to the femtomolar range. This review seeks to provide an exhaustive analysis of the most recent reports on the HPLC-ECD determination of 8-oxoG and 8-oxodG in cellular DNA and body fluids, which is relevant for health research.

Herbal Oils for Treatment of Chronic and Diabetic Wounds: A Systematic Review

BACKGROUND

In the present scenario, diabetes is a growing health challenge, and its occurrence is growing across the globe. Diabetes, with its complications like diabetic wounds, vasculopathy, neuropathy, wound infections, and oxidative stress, is a serious cause of mortality worldwide.

INTRODUCTION

Among the various complications, treatment of diabetic foot and ulcers is one of the major concerns in patients who are suffering from diabetes. The causative factors for this condition include increased oxidative stress, high blood glucose levels, vascular insufficiency, and microbial infections, and many a time, if left untreated, it may even lead to amputations of the lower extremities. The present therapy for the treatment of diabetic wounds mainly involves the use of synthetic moieties and other biotechnology-derived biomolecules, including growth factors. Few plant products are also useful in the treatment of wounds.

METHODS

Essential oils derived from various herbs are reported to possess significant wound healing potential and promote blood clotting, help to fight infections, and accelerate the wound healing process. Hence, the present review is a systematic analysis of all the available data on the use of the natural oils with their biological source, active phytochemical constituents present, and the probable mechanism of action for the treatment of chronic and diabetic wounds in suitable animal models. A methodical collection of data was performed, and information was searched up to April 2020 in entirety. Key phrases used for the data search include the pathophysiology of wounds, diabetic foot wound and its complications, natural oils for chronic and diabetic wound treatment.

RESULTS

This review summarizes the natural oils which are reported in the literature to be beneficial in the treatment of chronic wounds, while some oils have been specifically also studied against wounds in diabetic rats. Essential oils are said to interact with the body pharmacologically, physiologically and psychologically and help in rapid wound healing. However, the majority of the literature studies have demonstrated wound healing activity only in animal models (preclinical data), and further clinical studies are necessary.

CONCLUSION

This review provides a platform for further studies on the effective utilization of natural oils in the treatment of chronic and diabetic wounds, especially if oils are to receive credibility in the management of chronic wounds.

Associations of dietary, lifestyle, other participant characteristics, and oxidative balance scores with plasma F2-isoprostanes concentrations in a pooled cross-sectional study

PURPOSE

Plasma F₂-isoprostanes (FiP) concentration, a reliably measured, valid, systemic oxidative stress biomarker, has been associated with multiple health-related outcomes; however, associations of most individual dietary and lifestyle exposures with FiP are unclear, and there is no reported oxidative balance score (OBS) comprising multiple dietary and/or lifestyle components weighted by their associations with FiP.

METHODS

To investigate cross-sectional associations of dietary and lifestyle characteristics with plasma FiP concentrations, we used multivariable general linear models to compare adjusted mean FiP concentrations across categories of dietary nutrient and whole-food intakes and lifestyle characteristics in two pooled cross-sectional studies (n = 386). We also developed equal-weight and weighted OBS (nutrient- and foods-based dietary OBS, lifestyle OBS, and total OBS), and compared adjusted mean FiP concentrations across OBS tertiles.

RESULTS

Among men and women combined, adjusted mean FiP concentrations were statistically significantly, proportionately 28.1% higher among those who were obese relative to those who were normal weight; among those in the highest relative to the lowest total nutrient intake tertiles, FiP concentrations were statistically significantly lower by 9.8% for carotenes, 13.6% for lutein/zeaxanthin, 10.9% for vitamin C, 12.2% for vitamin E, 11.5% for glucosinolates, and 5% for calcium. Of the various OBS, the weighted OBS that combined total nutrient intakes and lifestyle exposures was most strongly associated with FiP concentrations: among those in the highest relative to the lowest total OBS, mean FiP concentrations were statistically significantly 29.7% lower (P < 0.001).

CONCLUSION

Multiple dietary and lifestyle characteristics, individually, and especially collectively, may contribute to systemic oxidative stress.

Biomarkers of DNA Oxidation Products: Links to Exposure and Disease in Public Health Studies

Environmental exposure can increase the production of reactive oxygen species and deplete cellular antioxidants in humans, resulting in oxidatively generated damage to DNA that is both a useful biomarker of oxidative stress and indicator of carcinogenic hazard. Methods of oxidatively damaged DNA analysis have been developed and used in public health research since the 1990s. Advanced techniques detect specific lesions, but they might not be applicable to complex matrixes (e.g., tissues), small sample volume, and large-scale studies. The most reliable methods are characterized by (1) detecting relevant DNA oxidation products (e.g., premutagenic lesions), (2) not harboring technical problems, (3) being applicable to complex biological mixtures, and (4) having the ability to process a large number of samples in a reasonable period of time. Most effort has been devoted to the measurements of 8-oxo-7,8-dihydro-2'-deoxyguanine (8-oxodG), which can be analyzed by chromatographic, enzymic, and antibody-based methods. Results from validation trials have shown that certain chromatographic and enzymic assays (namely the comet assay) are superior techniques. The enzyme-modified comet assay has been popular because it is technically simpler than chromatographic assays. It is widely used in public health studies on environmental exposures such as outdoor air pollution. Validated biomarker assays on oxidatively damaged DNA have been used to fill knowledge gaps between findings in prospective cohort studies and hazards from contemporary sources of air pollution exposures. Results from each of these research fields feed into public health research as approaches to conduct primary prevention of diseases caused by environmental or occupational agents.

Quantification of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydro-guanosine concentrations in urine and plasma for estimating 24-h urinary output

Among markers for oxidative stress urinary excretion 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and 8-oxo-7,8-dihydro-guanosine (8-oxoGuo) have been widely used in controlled and epidemiological studies, and are considered to represent intracellular markers of oxidation of DNA and RNA in the entire organism, respectively. Although being non-invasive, urinary methods have shortcomings. There is no established method for analysis of 8-oxodGuo and 8-oxoGuo in plasma and the few plasma values presented in the literature vary greatly. We here present a liquid chromatography mass spectrometry method with full validation for analysis of 8-oxodGuo and 8-oxoGuo in plasma. Further, we investigated the basis for our previously physiological model and show that a single plasma sample can be used to estimate the 24-h production of 8-oxoGuo, whereas we challenge the use of urinary 8-oxodGuo/creatinine ratio or plasma 8-oxodGuo as measures of oxidative stress.

8-Hydroxy-2-Deoxyguanosine as Oxidative DNA Damage Biomarker of Medical Ionizing Radiation: A Scoping Review

Background

Recent studies reported the significant expansion using 8-Hydroxy-2-Deoxyguanosine (8-OHdG) as a biomarker of oxidative Deoxyribonucleic Acid (DNA) damage among human populations exposed to medical ionizing radiation, but a generalized overview about this topic has not been conducted yet.

Objective

This scoping review of published literature examined recent trends in utilizing 8-OHdG biomarker to measure oxidative DNA damage induced by medical ionizing radiation and possible factors that may influence the 8-OHdG level.

Material and Methods

Literature search was conducted in PubMed, Scopus and ProQuest databases for publications from 1984 to 2/12/2020. Included articles were: cohort studies, case-control studies, and cross-sectional studies, randomized and nonrandomized controlled trials. Excluded articles were: editorials, letters, personal opinions, newspaper articles, study plans, protocols, qualitative studies, case reports and series, in-vivo and vitro studies, animal research studies, reviews and meta-analyses.

Results

According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we screened 141 articles, and 10 eligible studies met our inclusion criteria. All studies measured 8-OHdG as an oxidative DNA damage biomarker. The study results were contradictory concerning the relationship between the radiation dose and 8-OhdG level. 8-OHdG was mostly measured by enzyme-linked immunosorbent assay (ELISA) using urine samples. Sample size varied between (n=25-230) and included patients who underwent medical radiation procedures or workers exposed to ionizing radiation during their jobs.

Conclusion

This scoping review findings showed 8-OHdG can be used as a promising biomarker to detect oxidative damage, resulting from medical ionizing radiation exposure despite external factors that may influence 8-OHdG levels.

Higher systemic oxidatively generated DNA and RNA damage in patients with newly diagnosed bipolar disorder and their unaffected first-degree relatives

BACKGROUND

Prior studies in bipolar disorders (BD) have suggested that oxidative stress and cellular ageing play a key role in the pathophysiology of BD. Nevertheless, oxidative stress has not been investigated in patients with newly diagnosed BD and in their unaffected first-degree relatives (UR), compared with healthy control individuals (HC).

METHODS

We investigated the level of systemic oxidative damage to DNA and RNA measured by urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) levels, respectively, in 360 patients with newly diagnosed BD, 92 of their UR and 197 HC.

RESULTS

Independent of lifestyle and demographic variables, levels of both 8-oxoGuo and 8-oxodG was 17.1% (B = 1.171, 95%CI = 1.125-1.219, p < 0.001) and 21.2% (B = 1.212, 95%CI = 1.145-1.283, p < 0.001) higher, respectively, in patients with BD compared with HC and 13.3% (B = 1.133, 95%CI = 1.069-1.200, p < 0.001) and 26.6% (B = 1.266, 95%CI = 1.167-1.374, p < 0.001) higher, respectively, in UR compared with HC. Neither 8-oxoGuo nor 8-oxodG levels differed between patients with BD and UR. These findings were replicated in patients in full or partial remission and were consistent both in BD type I and II.

CONCLUSION

Overall, the findings of higher oxidative stress in patients with newly diagnosed BD and their UR suggest that systemic nucleoside damage by oxidative stress is present prior to onset and in the early stages of BD thereby potentially representing trait markers of BD.

Urinary biomarkers for secondhand smoke and heated tobacco products exposure

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

Purple corn extract (PCE) alleviates cigarette smoke (CS)-induced DNA damage in rodent blood cells by activation of AMPK/Foxo3a/MnSOD pathway

Purple corn extract (PCE) is a nutraceutical, an activator of AMPK, and it has antioxidants and anticancer properties. Therefore, PCE could be a candidate for alleviating cigarette smoke (CS)-induced oxidative DNA damage. This study examined whether PCE can have a protective effect on blood cells in an animal model of cigarette smoke (CS)-induced DNA damage. PCE was orally administered to CS-inhaled Spraque-Dawley (SD) rats, followed by the target cells being examined for markers of DNA damage. The study also sought to elucidate the mechanism of PCE action in the PCE treated animals. SD rat inhalation of CS was for once a day for 30 min, repeated for 7 days. PCE was administered orally before CS inhalation. Pretreatment of the animals with oral PCE kept the numbers of white blood cells (WBC) as well as neutrophils (NE), lymphocytes (LY), monocytes (Mo), eosinophils (EO), abd jasophils (BA) from increasing as those were increased in the CS-inhaling SD rats. The amount of phosphorylated γ-H2AX, a DNA damage marker, was assayed in the circulating blood cells collected from the animals and western blot analysis with anti-Foxo3a, p-Foxo3a, p-AMPK, MnSOD antibodies were performed on those cells. PCE protected the circulating blood cells from CS inhalation-induced DNA damage by 44% as assayed by increases in γ-H2AX. PCE also increased the nuclear localization of Foxo3a by 52% over control cells. Mechanistically, PCE appears to efficiently protect various blood cell types from CS-induced DNA damage through removal of ROS via activation of the AMPK/Foxo3a/MnSOD pathway.

Association between clinicopathological features of breast cancer with adipocytokine levels and oxidative stress markers before and after chemotherapy

Adipocytokines and markers of oxidative stress have been shown to exhibit potential for detection of advanced stage, HER2/neu status and lymph node metastases in patients with breast cancer, as well as in determining the efficiency of anti-cancer treatments. In the present study, blood concentrations of apelin (APLN), retinol-binding protein 4 (RBP4), 8-hydroxydeoxyguanosine (8-oxo-dG) and total antioxidant capacity (TAC) in women with breast cancer with different clinicopathological features were measured prior to and following adjuvant chemotherapy. The study included 60 women with breast cancer stratified according to tumor grade and size, HER-2/neu expression, and lymph node and hormone receptor status. Blood samples were taken before and after two cycles of adjuvant chemotherapy. None of the clinicopathological features were associated with the baseline concentrations of RBP4, 8-oxo-dG or TAC. An increased baseline concentration of APLN was observed in HER-2/neu positive patients. Moreover, through multivariate logistical regression analysis, APLN was shown to be independently associated with a positive HER/neu status. Chemotherapy treatment did not affect the levels of RBP4 or APLN, or TAC values when assessing all the patients, and when assessing the stratified groups of patients. Only 8-oxo-dG was found to be significantly decreased following drug administration (P=0.0009). This preliminary study demonstrated that APLN is a significant and independent predictor of HER-2/neu positive breast cancer. A significant reduction in 8-oxo-dG levels following chemotherapy may indicate its potential clinical utility in monitoring the effects of chemotherapy in breast cancer patients.

Biomarkers of nucleic acid oxidation - A summary state-of-the-art

Oxidatively generated damage to DNA has been implicated in the pathogenesis of a wide variety of diseases. Increasingly, interest is also focusing upon the effects of damage to the other nucleic acids, RNA and the (2′-deoxy-)ribonucleotide pools, and evidence is growing that these too may have an important role in disease. LC-MS/MS has the ability to provide absolute quantification of specific biomarkers, such as 8-oxo-7,8-dihydro-2′-deoxyGuo (8-oxodG), in both nuclear and mitochondrial DNA, and 8-oxoGuo in RNA. However, significant quantities of tissue are needed, limiting its use in human biomonitoring studies. In contrast, the comet assay requires much less material, and as little as 5 μL of blood may be used, offering a minimally invasive means of assessing oxidative stress in vivo, but this is restricted to nuclear DNA damage only. Urine is an ideal matrix in which to non-invasively study nucleic acid-derived biomarkers of oxidative stress, and considerable progress has been made towards robustly validating these measurements, not least through the efforts of the European Standards Committee on Urinary (DNA) Lesion Analysis. For urine, LC-MS/MS is considered the gold standard approach, and although there have been improvements to the ELISA methodology, this is largely limited to 8-oxodG. Emerging DNA adductomics approaches, which either comprehensively assess the totality of adducts in DNA, or map DNA damage across the nuclear and mitochondrial genomes, offer the potential to considerably advance our understanding of the mechanistic role of oxidatively damaged nucleic acids in disease.

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Oxidatively damaged nucleic acids are implicated in the pathogenesis of disease.

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LC-MS/MS, comet assay and ELISA are often used to study oxidatively damaged DNA.

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Urinary oxidatively damaged nucleic acids non-invasively reflect oxidative stress.

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DNA adductomics will aid understanding the role of ROS damaged DNA in disease.

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

OBJECTIVE

Oxidative stress is considered to cause lifestyle-related diseases, including cancer. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) is widely analyzed as an oxidative stress marker. We extensively scrutinized the relationships between 8-OHdG levels and lifestyle choices as carcinogenic factors.

METHODS

In this study, we investigated health examination results and working conditions affecting urinary 8-OHdG levels in 503 male workers.

RESULTS

The urinary 8-OHdG level was positively associated with high blood sugar and leanness in smokers. In addition, urinary 8-OHdG tended to increase with organic solvent or hydrochloric acid exposure, as well as long working hours. On the other hand, the urinary 8-OHdG level was negatively associated with high plasma LDL-cholesterol levels in non-smokers and anemia.

CONCLUSION

According to the results, anemia decreased the oxidative stress, regardless of smoking status, while leanness or high blood sugar increased the oxidative stress in smokers, and the presence of plasma cholesterol contributed to the lower oxidative stress in non-smokers. Certain types of occupational exposure may cause oxidative stress. The measurement of urinary 8-OHdG at annual health checks may be a useful biomarker for preventing lifestyle- and work-related diseases.

Reduction of oxidative stress on DNA and RNA in obese patients after Roux-en-Y gastric bypass surgery-An observational cohort study of changes in urinary markers

Increased oxidative stress in obesity and diabetes is associated with morbidity and mortality risks. Levels of oxidative damage to DNA and RNA can be estimated through measurement of 8-oxo-7,8-dihydro-2´-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) in urine. Both markers have been associated with type 2 diabetes, where especially 8-oxoGuo is prognostic for mortality risk. We hypothesized that Roux-en-Y gastric bypass (RYGB) surgery that has considerable effects on bodyweight, hyperglycemia and mortality, might be working through mechanisms that reduce oxidative stress, thereby reducing levels of the urinary markers. We used liquid chromatography coupled with tandem mass spectrometry to analyze the content of 8-oxodG and 8-oxoGuo in urinary samples from 356 obese patients treated with the RYGB-procedure. Mean age (SD) was 44.2 (9.6) years, BMI was 42.1 (5.6) kg/m2. Ninety-six (27%) of the patients had type 2 diabetes. Excretion levels of each marker before and after surgery were compared as estimates of the total 24-hour excretion, using a model based on glomerular filtration rate (calculated from cystatin C, age, height and weight), plasma- and urinary creatinine. The excretion of 8-oxodG increased in the first months after RYGB. For 8-oxoGuo, a gradual decrease was seen. Two years after RYGB and a mean weight loss of 35 kg, decreased hyperglycemia and insulin resistance, excretion levels of both markers were reduced by approximately 12% (P < 0.001). For both markers, mean excretion levels were about 30% lower in the female subgroup (P < 0.0001). Also, in this subgroup, excretion of 8-oxodG was significantly lower in patients with than without diabetes. We conclude, that oxidative damage to nucleic acids, reflected in the excretion of 8-oxodG and 8-oxoGuo, had decreased significantly two years after RYGB-indicating that reduced oxidative stress could be contributing to the many long-term benefits of RYGB-surgery in obesity and type 2 diabetes.

Effects of smoking cessation on biological monitoring markers in urine

INTRODUCTION

Urinary nicotine and cotinine levels are often measured as biomarkers for tobacco smoke exposure. However, these biomarkers are not appropriate to evaluate the effects of quitting smoking for several days, because of their short half-lives. In this study, we focused on the changes in the urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels of 55 patients in a smoking cessation program, because of the long half-life. At the same time, urinary 7-methylguanine (m7Gua) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), as DNA damage markers of cigarette smoking, were also measured.

RESULTS

In the subjects who completed the quit-smoking program (18 subjects out of 55), the urinary nicotine and cotinine levels decreased to 1.7 and 0.2% at 8 weeks after the first visit to the clinic. By contrast, the NNAL levels decreased to 12.3% at 8 weeks after quitting smoking. During the same period, the urinary m7Gua levels significantly decreased, from 27.32 μg/mg creatinine to 14.17 μg/mg creatinine by the elimination of subjects who showed increased levels of NNAL during the smoking cessation program. The 8-OHdG levels were also reduced within the same period, but were not significantly different. From the all data analysis, the urinary levels of cotinine and NNAL positively correlated with the level of m7Gua.

CONCLUSIONS

NNAL may be an appropriate exposure marker for evaluating the smoking status of patients in a smoking cessation program. The urinary cotinine and NNAL levels positively correlated with the m7Gua levels.

The Alteration of Pro-inflammatory Cytokines and Oxidative Stress Markers at Six-Month Post-living Kidney Donation

Donors have a higher risk of developing chronic kidney disease than the general population. Some mechanisms mediated by pro-inflammatory cytokines and oxidative stress may be involved as risk factors. The objective of the study was to evaluate the behavior of pro-inflammatory cytokines and oxidative stress markers in living renal donors with a 6-month follow-up. A single prospective cohort was performed in 88 renal donors. At the end of the follow-up, the levels of lipoperoxides, 6.52 ± 1.12 mM, and 8-isoprostanes, 63.75 ± 13.28 pg/mL, were lower than before donation, 10.20 ± 3.95 mM (p < 0.001) and 67.54 ± 9.64 pg/mL (p = 0.026), respectively. Initial levels of nitric oxide (NO), 356.09 ± 59.38 μM increased at the end of the follow-up, 467.08 ± 38.74 μM (p < 0.001). It was observed in the final determination of donors decreased activity of antioxidant enzymes superoxide dismutase (SOD), 0.74 ± 0.57 U/L and glutathione peroxidase (GPx), 556.41 ± 80.37 nmol, in comparison with the levels obtained in the initial determination, 1.05 ± 0.57 U/L (p < 0.001) and 827.93 ± 162.78 nmol (p < 0.001), respectively. The pro-inflammatory cytokines, Tumor necrosis factor alpha and interleukin-6 showed no differences at 6 months after donation. The enzyme oxoguanine glycosylase (hOGG1) responsible for repairing oxidative damage to DNA, showed a decrease in its concentration at the end of the study in donor men, 0.40 ± 0.21 ng/mL compared to the initial levels, 0.55 ± 0.32 ng/mL (p = 0.025). The marker, 8-hydroxy-2-deoxyguanosine (8-OHdG) exhibited an increase in donor men at the final determination 2.28 ± 1.99 ng/mL, compared to the concentration before donation, 1.72 ± 1.96 ng/mL (p < 0.001). We found significant changes in the markers of the oxidative state with increased NO and 8-OHdG, as well as a significant decrease in the antioxidant defenses SOD, GPx, and in the DNA repair enzyme in living renal donors after 6 months of follow-up.

Exposure to ZnO/TiO2 Nanoparticles Affects Health Outcomes in Cosmetics Salesclerks

Concerns about the effects of nanoparticles (NPs) on human health are being raised by researchers because the risks of nanocosmetics like sunscreen are unknown. We explored the association between urinary oxidative stress markers and exposure of cosmetics salesclerks to 20 cosmetics that might contain titanium dioxide (TiO₂)/zinc oxide (ZnO) NPs. We then recruited 40 cosmetics salesclerks and 24 clothing salesclerks and categorized them based on their exposure to ZnO and TiO₂ NPs. Nineteen and 15 samples met the EU definition for TiO₂ and ZnO nanomaterials, respectively. Participants with a higher co-exposure index of ZnO and TiO₂ NPs had a significantly higher base level of urinary 8-hydroxy-2′-deoxyguanosin (8-OHdG) concentrations than the lower co-exposure group (5.82 vs. 2.85 ng/mL, p < 0.001). After potential confounding factors had been adjusted for, the TiO₂ and ZnO NP co-exposure index was significantly positively associated with the urinary 8-OHdG base concentration (β = 0.308, 95% CI = 0.106 to 0.510) and the creatinine-adjusted concentration (β = 0.486, 95% CI = 0.017 to 0.954). Current evidence suggests that the likelihood of harm from using sunscreens containing nanoparticles might result in higher urinary 8-OHdG. However, our limited number and types of sample cosmetics might underestimate the risk.

The Effect of Body Mass Index on Treatment Outcomes in Patients with Metastatic Non-Small Cell Lung Cancer Treated with Platinum-Based Therapy

To investigate the effect of body mass index(BMI) on treatment outcomes and side-effect profile in metastatic non-small cell lung cancer(NSCLC) patients receiving platinum-based chemotherapy(ChT) in the first-line setting. This was a retrospective analysis of 233 NSCLC patients who were treated and followed up from 2008 through 2018. NSCLC patients who had metastatic disease at the time of diagnosis and were treated with platinum-based ChT in the first-line setting were included. The patients were divided into 2 groups based on the BMI as follows; BMI < 25 kg/m² and BMI ≥ 25 kg/m². This retrospective analysis enrolled 233 patients, 35 (15.0%) of whom were female. The BMI in 132 patients (56.2%) was < 25 kg/m². The median age was 58 years (range, 21-90). Median progression-free survival(PFS) was 7 mo, in the patients with BMI ≥ 25 kg/m² compared to 5.0 mo, in those with BMI < 25 kg/m² (p = 0.032), with corresponding median overall survival(OS) durations of 12 vs. 9 mo, (p = 0.003). In multivariate analysis, ECOG PS 2, grade III histology, and brain or bone metastasis negatively affected OS, whereas BMI ≥ 25 kg/m² positively affected OS. A high BMI prior to therapy in patients with NSCLC treated with platinum-based ChT in the first-line setting was associated with more favorable PFS and OS.

Urinary markers of nucleic acid oxidation increase with age, obesity and insulin resistance in Danish children and adolescents

PURPOSE

Oxidative stress may play an important role in childhood obesity and increased cardiometabolic risk. 8-oxo-7,8-dihydroguanosine (8-oxoGuo) from oxidation of RNA and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) from oxidation of DNA are excreted into urine and function as biomarkers for oxidative stress reflecting the modification rate of nucleic acids by oxidation. This study investigates the associations between urinary markers of nucleic acid oxidation and Body Mass Index (BMI), age, sex and cardiometabolic risk factors in children and adolescents with and without obesity.

METHODS

We studied 543 children and adolescents from an obesity clinic cohort (n = 418) and a population-based cohort (n = 125), all aged 6-18 years. Anthropometrics, urine and blood samples were collected. A validated liquid chromatography-tandem mass spectrometry method was used to measure the nucleic acid oxidation markers.

RESULTS

Compared with the population-based cohort, children and adolescents in the obesity clinic cohort had higher calculated 24-h excretion of 8-oxoGuo (p = 0.045) and 8-oxodG (p = 0.014) adjusted for basal metabolic rate. Both oxidation markers were positively associated with age and female sex (all p < 0.002). In the obesity clinic cohort the RNA oxidation marker 8-oxoGuo correlated with serum insulin (rho = 0.18, p = <.001) and insulin resistance (rho = 0.19, p = <.001).

CONCLUSIONS

Childhood obesity associate with higher urinary excretion of nucleic acid oxidation biomarkers, and increase with age throughout childhood, mirroring the obesity- and age-related increase shown in adults. Finally, children with obesity and insulin resistance had higher RNA oxidation markers than children with obesity and no insulin resistance, supporting a possible link between oxidative stress and the pathogenesis of cardiometabolic risk including type 2 diabetes.

A simple and useful method for evaluation of oxidative stress in vivo by spectrofluorometric estimation of urinary pteridines

Pteridine derivatives are intermediate metabolites of folic acid and its cofactors. Oxidized-form pteridines, but not reduced-form pteridines, are fluorescent substances. The purpose of this study was to clarify whether oxidized-form pteridine level in urine, estimated by spectrofluorometry, reflects oxidative stress in vivo. The subjects were healthy middle-aged men (n = 258). Urinary pteridine level was estimated by spectrofluorometry with an excitation wavelength of 360 nm and an emission wavelength of 450 nm. Relationships of urinary pteridines with oxidative stress markers (urinary DNA/RNA oxidation products and 15-isoprostane F_2t) and with smoking were analyzed. Concentrations of pteridines, DNA/RNA oxidation products and 15-isoprostane F_2t were used after logarithmic transformation in linear analyses. Pteridine levels were significantly correlated with levels of DNA/RNA oxidation products (Pearson’s correlation coefficient: 0.626, p < 0.01) and 15-isoprostane F_2t (Pearson’s correlation coefficient: 0.695, p < 0.01). These correlations were not confounded by age, body mass index, history of smoking and estimated glomerular filtration rate in multivariate analysis. The mean urinary pteridine level was significantly higher in heavy smokers (16 cigarettes or more per day) than in nonsmokers and light smokers (less than 16 cigarettes per day) and was higher in light smokers than in nonsmokers. Thus, urinary fluorometric pteridine levels were shown to be associated with known biomarkers of oxidative stress as well as smoking, which causes oxidative stress in vivo. We propose spectrofluorometrical estimation of urinary pteridines as a simple and useful method for evaluation of oxidative stress in vivo.

Increased levels of 5',8-Cyclopurine DNA lesions in inflammatory bowel diseases

Chronic inflammation is estimated to be a causative factor in a variety of diseases. Under inflammatory conditions reactive oxygen species (ROS) and nitrogen species (RNS) are released leading to DNA damage accumulation and genomic instability. Purine 5′,8-cyclo-2′-deoxynucleosides (cPu) are oxidative DNA lesions, exclusively derived from the attack of HO^• radicals, which are known to have cytotoxic and mutagenic properties. Herein, we have analyzed the presence of cPu in genomic DNA isolated from fresh colon and visceral adipose tissue biopsies collected from inflammatory bowel diseases (IBD)-affected patients and severely obese subjects, respectively, versus what observed in the control specimens. In colon biopsies, characterized by a higher gene expression level of inducible nitric oxide synthase (iNOS), a significant increase of 8-oxo-7,8-dihydro-2′-deoxyadenosine (8-oxo-dA) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) lesions and an accumulation of both diastereomeric cPu have been detected. In contrast, the 8-oxo-dA and 8-oxo-dG levels were extremely lower compared to the colon tissues values and no accumulation of cPu, in the inflamed visceral adipose tissue biopsies isolated from bariatric patients versus the lean counterpart was reported. In addition, in adipose tissue undetectable levels of iNOS have been found. These data suggest a potential involvement of cPu in the colon cancer susceptibility observed in IBD patients.

Aging-related lipidomic changes in mouse serum, kidney, and heart by nanoflow ultrahigh-performance liquid chromatography-tandem mass spectrometry

Aging refers to the intracellular accumulation of reactive oxygen species that damages proteins, DNA, and lipids. As alterations in lipid metabolism may trigger metabolic disorders and the onset of metabolic diseases, changes in lipid profiles can be closely related to aging. In this study, a comprehensive lipidomic comparison between 4- and 25-month-old mice was performed to investigate age-induced changes in the lipid profiles of mouse serum, kidney, and heart using nanoflow ultrahigh-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. Quantitative analysis of 279 of the 542 identified lipids revealed significant changes upon aging, mainly showing decreased levels in the three types of samples. Exceptionally, most triacylglycerols showed significant increases in heart tissue. The kidney was influenced more by aging than the serum and heart. The highly abundant lipids in each lipid class with significant decreases (> 2-fold, p < 0.01) were lysophosphatidic acid 18:1, lysophosphatidylinositol 20:4, and ceramide d:18:1/24:0 in serum; lysophosphatidylglycerol 16:0 in heart tissue; and eight phosphatidylethanolamines (20:4, 22:6, 36:2, 36:3, 38:4, 38:5, 38:6, 40:6, and 40:7), two cardiolipins (72:7 and 72:8), and lysophosphatidylcholine 18:0 in kidney tissue. The findings indicate the potential of lipidomic analysis to study characteristic age-related lipid changes.

Mitochondrial DNA somatic mutation burden and heteroplasmy are associated with chronological age, smoking, and HIV infection

The gradual accumulation of mitochondrial DNA (mtDNA) mutations is implicated in aging and may contribute to the accelerated aging phenotype seen with tobacco smoking and HIV infection. mtDNA mutations are thought to arise from oxidative damage; however, recent reports implicate polymerase γ errors during mtDNA replication. Investigations of somatic mtDNA mutations have been hampered by technical challenges in measuring low-frequency mutations. We use primer ID-based next-generation sequencing to quantify both somatic and heteroplasmic blood mtDNA point mutations within the D-loop, in 164 women and girls aged 2-72 years, of whom 35% were smokers and 56% were HIV-positive. Somatic mutations and the occurrence of heteroplasmic mutations increased with age. While transitions are theorized to result from polymerase γ errors, transversions are believed to arise from DNA oxidative damage. In our study, both transition and transversion mutations were associated with age. However, transition somatic mutations were more prevalent than transversions, and no heteroplasmic transversions were observed. We also measured elevated somatic mutations, but not heteroplasmy, in association with high peak HIV viremia. Conversely, heteroplasmy was higher among smokers, but somatic mutations were not, suggesting that smoking promotes the expansion of preexisting mutations rather than de novo mutations. Taken together, our results are consistent with blood mtDNA mutations increasing with age, inferring a greater contribution of polymerase γ errors in mtDNA mutagenesis. We further suggest that smoking and HIV infection both contribute to the accumulation of mtDNA mutations, though in different ways.

Oxidatively generated modifications to nucleic acids in vivo: Measurement in urine and plasma

BACKGROUND

The oxidized guanine nucleosides, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), derived from DNA and RNA, respectively, were used to investigate the importance of oxidative stress to nucleic acids in vivo. High urinary excretion of 8-oxodG is associated with cancer development, whereas high urinary excretion of 8-oxoGuo is associated with mortality in type 2 diabetes. Like creatinine, these small water-soluble molecules are not reabsorbed in the kidney. Therefore, 8-oxo nucleoside/creatinine reciprocal concentration ratios are identical in plasma and urine. The total amount of 8-oxo guanine nucleosides excreted by the kidneys is the product of plasma concentration and glomerular filtration rate.

METHODS

With relevant equations and an estimated glomerular filtration rate, the 24-h urinary excretion of 8-oxodG and 8-oxoGuo was calculated in 2679 subjects with type 2 diabetes, displaying good correlation with the measured urinary 8-oxo nucleoside/creatinine ratio: DNA oxidation r = 0.86 and RNA oxidation r = 0.84 (p < 0.05 for both).

RESULTS

Survival analyses based on the quartiles of the 8-oxodG/creatinine ratio and the quartiles of calculated 24-h urinary excretion rate of the 2679 subjects gave similar hazard ratio estimates for death due to all causes. This finding was similar for the 8-oxoGuo hazard ratio estimates.

CONCLUSIONS

This study shows that oxidatively generated modifications to DNA and RNA in vivo can be measured using 1) a spot urine sample, normalized to urinary creatinine, 2) 24-h urine, or 3) a single plasma sample based on concentrations of 8-oxo nucleoside and creatinine and glomerular filtration rate.

Developing an elegant and integrated electrochemical-theoretical approach for detection of DNA damage induced by 4-nonylphenol

In this work, a novel biosensor was fabricated for detection of DNA damage induced by 4-nonylphenol (NP) and also determination of NP. To achieve this goal, a glassy carbon electrode (GCE) was modified with chitosan (Chit), gold nanoparticles (Au NPs) and DNA-multiwalled carbon nanotubes (DNA-MWCNTs). Then, the DNA-MWCNTs/Au NPs/Chit/GCE was incubated with methylene blue (MB) to obtain MB-DNA-MWCNTs/Au NPs/Chit/GCE in which MB was used as the redox indicator. The modifications applied to the GCE were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopic (EDS) and theoretical evidence. MB is a derivative of anthraquinone which can intercalate into double helix structure of DNA. By treating MB-DNA-MWCNTs/Au NPs/Chit/GCE with NP, a higher R _ct was observed because the insertion of the NP may result in a more negative charge environment on the DNA surface which hinders accessibility of [Fe(CN)₆]^3-/4- anion to the electrode surface. Change in the EIS response of the biosensor in the presence of NP was used to develop a novel system for monitoring the DNA damage induced by NP. The EIS technique was also used to develop a sensitive electroanalytical method for determination of NP.

Pleiotropic association of LIPC variants with lipid and urinary 8-hydroxy deoxyguanosine levels in a Taiwanese population

BACKGROUND

Hepatic lipase (HL, encoded by LIPC) is a glycoprotein primarily synthesized and secreted by hepatocytes. Previous studies had demonstrated that HL is crucial for reverse cholesterol transport and affects the metabolism, composition, and level of several lipoproteins. In current study, we investigated the association of LIPC (Lipase C, Hepatic Type) variants with circulating and urinary biomarker levels by using subgroup and mediation analyses.

METHODS

A total of 572 participants from Taiwan were genotyped for three LIPC single nucleotide polymorphisms (SNPs) by using TaqMan assay. Fasting levels of glucose, lipid profile, inflammation markers, urine creatinine and 8-hydroxy deoxyguanosine (8-OHdG) were measured. The chi-square test, 2-sample t test and Analysis of variance (ANOVA) were used to examine differences among variables and genotype frequencies.

RESULTS

SNPs rs2043085 and rs1532085 were significantly associated with urinary 8-OHdG levels, whereas all three SNPs were more significantly associated with Triglycerides (TG) or HDL-cholesterol (HDL-C) levels after additional adjustment for HDL-C or TG levels, respectively. Subgroup analyses revealed that the association of the LIPC SNPs with the levels of serum TG, HDL-C, and urinary 8-OHdG were predominantly observed in the men but not in the women. Differential associations of the LIPC SNPs with various lipid levels were observed in participants with different adiposity statuses. Mediation analyses indicated that TG levels acted as a suppressor masking the association of the LIPC genotypes with HDL-C levels, particularly in the men (Sobel test, all P < 0.01).

CONCLUSION

Our data revealed that interaction and suppression effects mediated the pleiotropic association of the LIPC variants. The effects of the LIPC SNPs depended on sex, adiposity status, and TG levels. Thus, our findings can provide a method for identifying high-risk populations of cardiovascular diseases for clinical diagnosis.

Heteroxenia Ghardaqensis Extract Protects Against DNA Damage in Streptozotocin-Induced Experimental Diabetes

DNA damage is correlated to type-2 diabetes mellitus (T2DM) and its complications via oxidative stress. This study aimed to evaluate the anti-diabetic effect of Heteroxenia ghardaqensis extract on streptozotocin (STZ) induced-diabetes and how far can this extract attenuate DNA damage in this model. Forty male albino rats (160-180 g) were used in this study and divided into four groups: control, diabetic, diabetic rats received H. ghardaqensis extract (30 mg/kg body weight/day) orally for four weeks and diabetic rats received H. ghardaqensis extract (60 mg/kg body weight/day) orally for four weeks. After the experimental period, fasting blood sugar and serum cholesterol were determined. Urinary 8-hydroxyguanosine (8-OHdG) as a marker of DNA damage was estimated by reversed phase (HPLC). Liver and kidney nitic oxide (NO) and malondialdehyde (MDA) were estimated. Pancreatic tissues were histopathologicaly examined. Our results suggested that diabetes mellitus is accompanied by elevation of DNA damage that enhances the tendency to mutagens and reduce the efficacy of DNA repair. H. ghardaqensis extract appeared to be effective against the oxidative stress induced by STZ which may be due to sesquiterpenoids and diterpenes compounds that scavenge free radicals and increase the antioxidant enzymes as appeared in attenuation of DNA damage.

Changes in oxidative stress levels during two weeks of smoking cessation treatment and their association with nutritional characteristics in Japanese smokers

Although several experimental studies have reported that oxidative stress levels decrease during smoking cessation, how they change among general smokers has yet to be completely elucidated. In the present study, a total of 23 smokers who underwent smoking cessation treatment were observed for two-week changes in their levels of 8-OHdG and 8-isoprostane. Physical and nutritional characteristics were measured at the initial patient visit, and casual urine samples were collected at the initial visit and at a follow-up visit two weeks later. Oxidative stress was measured by a high performance liquid chromatography electrochemical detector, and the two-week difference in the levels of oxidative stress was assessed according to demographic and nutrient factors. Neither the urinary level of 8-OHdG nor that of 8-isoprostane decreased, although the cotinine level was decreased at two weeks. A Two-way repeated ANOVA revealed a significant interaction for fat intake by time for the change in the 8-OHdG level (P=0.03) and significant interactions for α-tocopherol intake (P=0.03), iron intake, and carbohydrate intake (P=0.03), all of which were time-dependent for the change in the 8-isoprostane level. The 8-OHdG level decreased among smokers with a high fat intake and was increased with a low fat intake. The 8-isoprostane levels were decreased among smokers with a high carbohydrate intake and increased with a low carbohydrate intake, decreased with a low iron intake and increased with a high iron intake and decreased with a low α-tocopherol intake and increased with a high α-tocopherol intake. Although the present study failed to observe a decrease in oxidative stress levels during the two-week smoking cessation period, we hypothesize that the intake levels of specific nutrients when initiating smoking cessation treatment may predict any subsequent changes in the oxidative stress levels.

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.

Statin treatment, oxidative stress and inflammation in a Danish population

Background

While 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.

Methods

We 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.

Results

Compared 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%, p_interaction<0.001) and 3.9% lower 8-oxoGuo (95%CI: 0.1–7.5%, p_interaction = 0.002), compared with non-users. Compared with non-users, statin users had 11.1% (95%CI: 5.4–16.5%, p_interaction<0.001) lower 8-oxodG in participants treated for hypertension, and 18.6% (95%CI: 6.8–28.9%, p_interaction<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.

Conclusions

Oxidatively 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.

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Statin users have lower oxidatively generated DNA damage than non-users.

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The protective effect of statins is more pronounced in high-risk groups.

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Statin users have lower levels of chronic inflammation than non-users.

Lipid damage is the best marker of oxidative injury during the cardiac remodeling process induced by tobacco smoke

BACKGROUND

Oxidative stress is one potential mechanism that explain the direct effects of smoking on cardiac remodeling process. However, no study has compared different myocardial products of macromolecule oxidation after tobacco smoke exposure. Thus, the aim of this study was to investigate the lipid hydroperoxide (LH) levels, protein carbonyl concentrations and DNA damage in cardiac tissue of rats exposed to tobacco smoke.

METHODS

Male Wistar rats were divided into two groups: group C (control, n = 14) composed of animals not exposed to cigarette smoke; group ETS (exposed to tobacco smoke, n = 14) composed by animals exposed to cigarette smoke. The animals were exposed to 2 month of ETS and morphological, biochemical and functional analyses were performed.

RESULTS

Cardiac cotinine levels were elevated in the ETS group. In addition, the myocyte cross-sectional area was higher in the ETS group. (C = 266.6 ± 23.2 μm2 and ETS = 347.5 ± 15.1 μm2, p <  0.001). Cardiac LH was higher in the ETS group than in group C (C = 196.4 ± 51.5 nmol/g and ETS = 331.9 ± 52.9 nmol/g, p <  0.001). However, there were no between-group differences in cardiac protein carbonyl concentration or DNA damage.

CONCLUSIONS

Therefore, our results suggest that, in this model, lipid damage is a good marker of oxidative damage during the cardiac remodeling process induced by 2 months of exposure to tobacco smoke.

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.

Systemic Expression of Oxidative DNA Damage and Apoptosis Markers in Acute Renal Graft Dysfunction

Background: Acute renal graft dysfunction (AGD) is one of the primary complications after kidney transplantation. The aim of this study was to identify the systemic oxidative DNA damage and apoptosis markers in patients with AGD, which will aid the understanding of the underlying processes of the complication. Methods: A cross-sectional analytical study was conducted in renal transplant (RT) recipients with and without AGD. The follow-up time of patients was <1 year. Using the ELISA technique, the markers of oxidative DNA damage (8-hydroxy-2-deoxyguanosine and 8-oxoguanine-DNA-N-glycosylase-1) and apoptosis (caspase-3, caspase-8, soluble TNF receptor 1, and cytochrome C) were determined. Results: Donor age was significantly higher in patients with AGD versus those without AGD (43±11 years versus 34.1±10.6 years, respectively; p<0.001). Levels of 8-hydroxy-2-deoxyguanosine were also significantly higher in AGD patients than those without AGD (624.1±15.3 ng/mL and 563.02± 17.4 ng/mL, respectively; p=0.039) and the DNA repair enzyme 8-oxoguanine-DNA-N-glycosylase-1 was significantly diminished in AGD patients versus non-AGD patients (7.60±1.8 ng/mL versus 8.13±1.70 ng/mL, respectively; p=0.031). A significant elevation of soluble TNF receptor levels in AGD patients was also found versus those without AGD (1178.6±25.2 ng/mL versus 142.6±39 ng/mL, respectively; p=0.03). Caspase-3 levels were higher in patients with AGD (1.19±0.21 ng/mL) versus those without AGD (0.79±0.11 ng/mL; p=0.121) and was also significantly augmented in AGD versus healthy control subjects (0.24±0.1 ng/mL; p=0.036). Cytochrome c in AGD patients was 0.32±0.09 ng/mL and 0.16±0.03 ng/mL in those without AGD versus 0.08±0.01 ng/mL in healthy controls (p=0.130 and p=0.184, respectively). Conclusion: These findings suggest that oxidative DNA damage with insufficient DNA repair and higher levels of caspase-3 compared to controls are markers of apoptosis protein dysregulation in AGD patients.