Determination of 8-hydroxydeoxyguanosine by an immunoaffinity chromatography-monoclonal antibody-based ELISA

Oxidative Stress, DNA Damage, Ethoxyresorufin-O-deethylase Induction and Neurotoxicity Caused by Environmental Pollutants in Cyprinus carpio (Linnaeus, 1758) from Atatürk Dam Lake (Türkiye)

Increasing population, industrial developments and agricultural activities around Atatürk Dam Lake, the largest dam of Türkiye, are also increasing level of pollutants in this reservoir. Catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), ethoxyresorufin-O-deethylase (EROD), 8-Hydroxy-2'-deoxyguanosine (8-OHdG), and acetylcholinesterase (AChE) in tissues of Cyprinus carpio caught from Samsat (relatively clean), Sitilce (affected by domestic/industrial wastes) and Bozova (affected by agricultural activities) regions of dam lake were analyzed in this work. Significant declines in SOD, AChE and GSH (P < 0.05) and significant elevations in CAT, EROD, 8-OHdG and MDA (P < 0.05) were observed in fish from Sitilce and Bozova regions compared to Samsat region. In Sitilce and Bozova, while these elevations were 54% and 121% for EROD, 40% and 92% for 8-OHdG, these declines were 33% and 58% for SOD, 29% and 55% for AChE, respectively. Our research shows environmental pollutants cause oxidative damage and neurotoxicity in fish from Atatürk Dam Lake.

Toxic Effects of Imidacloprid, Copper Sulfate, and Their Combinations on Biomolecular and Oxidative/Antioxidant Biomarkers in the Tissues of Oreochromis niloticus

The wide-ranging use of heavy metals and pesticides worldwide and their irreversible accumulation in aquatic ecosystems is a major concern. As the range of household and agricultural chemicals increases, water pollution is trending from the toxic effects of a single agent to complex agent pollution that threatens aquatic ecosystems. The aim of this study was to investigate the effects of pesticides (imidacloprid, IMI) and metals (copper sulfate, CuSO4) on oxidative stress biomarkers, antioxidant enzymes, and biomolecular parameters. The present study on the individual and combined effects of Oreochromis niloticus copper sulfate (CuSO4; 1 ppm), imidacloprid (IMI; 10 and 50 ppm), and IMI + CuSO4 (IMI10 + CuSO4, IMI50 + CuSO4) groups for 14 days. In this context, oxidative stress/antioxidant markers (SOD, CAT, GST, and GSH) and biomolecular markers including HSP70, 8-OHdG, PC, and TBARS levels were examined in fish liver and kidney tissues, which are detoxification organs. The results indicated that IMI and CuSO4 toxicity alone and in combination altered oxidative stress/antioxidant markers and biomolecular parameters; moreover, 14 days of exposure to the combination of CuSO4 and imidacloprid in particular exhibited a synergistic effect and caused oxidative toxicity. These findings highlighted the importance of evaluating mixtures of pesticides and metals and that the results show a remarkably synergistic effect. It can be concluded that these biomarkers are important indicators of physiological changes in living organisms.

Tripodal Quinone-Cyanine G-Quadruplex Ligands as Novel Photosensitizers on Photoinduced Cancer Cell Death

Guanine-quadruplex (G4) selective photosensitizers have huge potential for photodynamic therapy against various diseases correlated with G4 DNA and G4 RNAs; however, the types of photosensitizer skeletons available are limited. Herein, we investigated the ability of our original G4 ligands, tripodal quinone-cyanine dyes (tpQCy(s)), which were developed as fluorescent probes for G4, to act as photosensitizers for cancer-selective apoptosis inducers. The results indicated that the tpQCy skeleton has great potential for developing G4-targeted cancer-selective photosensitizers for photodynamic therapy. Among the two tpQCys, only QCy(BnBT)3, which has greater G4 selectivity, exhibited photoinduced cytotoxicity in HeLa cell growth, suggesting that the direct oxidation of G4 DNA or RNA is crucial for photoinduced cytotoxicity. RNA-seq analysis using a next-generation sequencing technique revealed that apoptosis was clearly induced by photoirradiation after QCy(BnBT)3 treatment.

Acute copper stress showed toxic effects on the physiological metabolism of Ulva lactuca, a common green macroalgae

The pollution by heavy metals in coastal waters has gradually intensified due to industrial development. In this study, physiological responses of Ulva lactuca, one of the most common green seaweeds with important ecological and economic value in the global intertidal zone, to acute copper stress were investigated. Results showed that an increase in copper ions concentration significantly inhibited photosynthetic activity and inorganic nitrogen utilization by U. lactuca but, increased its respiration. Copper stress limited the activity and gene expression of enzymes related to carbon and nitrogen assimilation of U. lactuca. Under moderate copper stress, U. lactuca had higher soluble carbohydrate and soluble protein contents, whereas under high copper stress, these components decreased sharply. Copper stress increased malonaldehyde content, and relative electrical conductivity in U. lactuca, but changes in antioxidant enzyme activities were not significant and even slightly decreased. Moreover, the contents of 8-hydroxy-deoxyguanosine and polyADP ribose polymerase in U. lactuca increased by high Cu2+ concentration culture, indicating that oxidative damage caused by high Cu2+ level involved its DNA damage and interfered with DNA repair in the alga. Copper stress seemed to be more damaging to the carbon assimilation process of U. lactuca, resulting in weakened resistance to copper stress and lower growth rate. This reflected the threat of coastal high copper stress to intertidal biodiversity. This provided ecological reference for the assessment of offshore heavy metal pollution represented by copper.

Prevotella copri transplantation promotes neurorehabilitation in a mouse model of traumatic brain injury

BACKGROUND

The gut microbiota plays a critical role in regulating brain function through the microbiome-gut-brain axis (MGBA). Dysbiosis of the gut microbiota is associated with neurological impairment in Traumatic brain injury (TBI) patients. Our previous study found that TBI results in a decrease in the abundance of Prevotella copri (P. copri). P. copri has been shown to have antioxidant effects in various diseases. Meanwhile, guanosine (GUO) is a metabolite of intestinal microbiota that can alleviate oxidative stress after TBI by activating the PI3K/Akt pathway. In this study, we investigated the effect of P. copri transplantation on TBI and its relationship with GUO-PI3K/Akt pathway.

METHODS

In this study, a controlled cortical impact (CCI) model was used to induce TBI in adult male C57BL/6J mice. Subsequently, P. copri was transplanted by intragastric gavage for 7 consecutive days. To investigate the effect of the GUO-PI3K/Akt pathway in P. copri transplantation therapy, guanosine (GUO) was administered 2 h after TBI for 7 consecutive days, and PI3K inhibitor (LY294002) was administered 30 min before TBI. Various techniques were used to assess the effects of these interventions, including quantitative PCR, neurological behavior tests, metabolite analysis, ELISA, Western blot analysis, immunofluorescence, Evans blue assays, transmission electron microscopy, FITC-dextran permeability assay, gastrointestinal transit assessment, and 16 S rDNA sequencing.

RESULTS

P. copri abundance was significantly reduced after TBI. P. copri transplantation alleviated motor and cognitive deficits tested by the NSS, Morris's water maze and open field test. P. copri transplantation attenuated oxidative stress and blood-brain barrier damage and reduced neuronal apoptosis after TBI. In addition, P. copri transplantation resulted in the reshaping of the intestinal flora, improved gastrointestinal motility and intestinal permeability. Metabolomics and ELISA analysis revealed a significant increase in GUO levels in feces, serum and injured brain after P. copri transplantation. Furthermore, the expression of p-PI3K and p-Akt was found to be increased after P. copri transplantation and GUO treatment. Notably, PI3K inhibitor LY294002 treatment attenuated the observed improvements.

CONCLUSIONS

We demonstrate for the first time that P. copri transplantation can improve GI functions and alter gut microbiota dysbiosis after TBI. Additionally, P. copri transplantation can ameliorate neurological deficits, possibly via the GUO-PI3K/Akt signaling pathway after TBI.

Comparative evaluation of salivary, serum and urinary 8-OHdG in gutka-associated oral submucous fibrosis

Background

Gutka chewing is the most common deleterious oral habit prevalent in the geographical distribution of the Indian subcontinent. Gutka leads to the production of numerous free radicals, which causes oxidative stress in regional oral tissues. Oxidative stress brings about the oxidation of guanine bases of DNA that generates 8-OHdG as its main byproduct. The presence of 8-OHdG can be evaluated not only in tissue but also in saliva, blood and urine. The availability of 8-OHdG in these samples is quite documented. In addition, a comparative assay of 8-ohdg DNA damage marker in multiple samples is yet to be done.

Material and Methodology

A sample size of 60 was divided into two groups, i.e., gutka consumers without any lesion and gutka consumers with OSMF. Ten samples each of saliva, serum and urine were collected from these two groups and healthy controls. Samples were centrifuged at 1000 RPM at 2-8°C for 15-20 minutes. A volume of 1.5 ml resultant supernatant was pipetted out in labelled Eppendorf tubes and stored at -80°C. The ELISA test was performed to measure the concentration of 8-OHdG protein in different samples at 450 nm after adding stop solution in 96-well microplate.

Results

8-OHdG concentration was found to be highest in saliva followed by urine and serum. 8-OHdG concentration in serum was significantly less than that in saliva and urine (P-value <0.05). Intergroup difference in concentration of 8-OHdG of urine, saliva and serum was significant (P-value <0.05). Post hoc analysis revealed that concentration of 8-OHdG in saliva and urine was non-significantly different (P-value >0.05).

Conclusion

Saliva appears to be the most appropriate sample type as compared to serum and urine for the evaluation of 8-OHdG in OSMF subjects.

Biological autoluminescence as a perturbance-free method for monitoring oxidation in biosystems

Biological oxidation processes are in the core of life energetics, play an important role in cellular biophysics, physiological cell signaling or cellular pathophysiology. Understanding of biooxidation processes is also crucial for biotechnological applications. Therefore, a plethora of methods has been developed for monitoring oxidation so far, each with distinct advantages and disadvantages. We review here the available methods for monitoring oxidation and their basic characteristics and capabilities. Then we focus on a unique method - the only one that does not require input of additional external energy or chemicals - which employs detection of biological autoluminescence (BAL). We highlight the pros and cons of this method and provide an overview of how BAL can be used to report on various aspects of cellular oxidation processes starting from oxygen consumption to the generation of oxidation products such as carbonyls. This review highlights the application potential of this completely non-invasive and label-free biophotonic diagnostic method.

Toxicological Impacts on Antioxidant Responses, Stress Protein, and Genotoxicity Parameters of Aluminum Oxide Nanoparticles in the Liver of Oreochromis niloticus

The aim of this study was to determine the toxic effects of aluminum oxide nanoparticles (Al₂O₃ NPs) on oxidative stress, stress protein, and genotoxicity parameters in Oreochromis niloticus. Ninety-six-hour LC₅₀ value of Al₂O₃ NPs was found as 52.4 ppm for O. niloticus. The fish were exposed to 2.6 ppm (5% of the 96-h LC₅₀) and 5.2 ppm (10% of the 96-h LC₅₀) for 3 days and 7 days. Various biochemical parameters, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) activities, glutathione (GSH), thiobarbituric acid reactive substance (TBARS), heat shock protein 70 (HSP70; stress protein), and genotoxicity biomarker 8-hydroxy-2-deoxyguanosine (8-OHdG) levels, were determined. Results showed that antioxidant enzymes were significantly decreased in SOD, CAT, and GPx enzyme activity, but GST enzyme activity was significantly increased in 7 days. The oxidative stress parameters, GSH levels, were significantly decreased while 8-OHdG and TBARS levels were increased in 3 and 7 days. HSP70 levels were decreased in the concentrations of Al₂O₃ NPs and exposure times. Our results showed that as a result of changes in oxidative stress parameters, stress protein, and genotoxicity parameters, O. niloticus liver tissue is highly sensitive and toxic to aluminum oxide nanoparticle exposure.

In vivo neurotoxic effects of emamectin benzoate in male mice: evaluation with enzymatic and biomolecular multi-biomarkers

The study of the toxic effects of emamectin benzoate (EMB) was conducted in male mice. Mice were randomly divided into 4 groups; control group, EMB25 group (1/30 LD₅₀ = 25 mg/kg/day), EMB50 group (1/15 LD₅₀ = 50 mg/kg/day), and EMB100 group (1/7.5 LD₅₀ = 100 mg/kg/day). Control group received water (placebo), and EMB groups were administered by oral gavage for 14 days. The superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) enzyme activities, thiobarbituric acid reactive substance (TBARS) and protein carbonyl (PC) levels, and adenosine triphosphatase (ATPases) enzymes, which are ion transport enzymes (Na⁺/K⁺ ATPase, Ca⁺² ATPase, Mg⁺² ATPase), acetylcholinesterase (AChE, neurotoxicity biomarker), and myeloperoxidase (MPO) enzyme activities (inflammatory biomarker), were measured by spectrophotometric methods. 8-Hydroxy-2'-deoxyguanosine level (8-OHdG, DNA oxidation biomarker) was measured by enzyme-linked immunosorbent analysis (ELISA) technique. The results showed a decrease in SOD, CAT and GPx enzyme activities in the brain tissue and an increase in GST enzyme activity in the EMB groups compared to the control group. Meanwhile, the enzyme activities of the ion transport enzymes Na⁺/K⁺ ATPase, Ca⁺² ATPase, and Mg⁺² ATPase, and AChE enzyme activity showed significant inhibition. In addition, MPO enzyme activity, 8-OHdG, PC, and TBARS levels were increased. The results showed that dose-dependent EMB exposure induced different physiological processes with enzymatic and biomolecular multi-biomarkers in the brain tissue of male mice and caused neurotoxic effects.

Genome-wide analysis of 8-oxo-7,8-dihydro-2'-deoxyguanosine at single-nucleotide resolution unveils reduced occurrence of oxidative damage at G-quadruplex sites

8-Oxo-7,8-dihydro-2′-deoxyguanosine (OG), one of the most common oxidative DNA damages, causes genome instability and is associated with cancer, neurological diseases and aging. In addition, OG and its repair intermediates can regulate gene transcription, and thus play a role in sensing cellular oxidative stress. However, the lack of methods to precisely map OG has hindered the study of its biological roles. Here, we developed a single-nucleotide resolution OG-sequencing method, named CLAPS-seq (Chemical Labeling And Polymerase Stalling Sequencing), to measure the genome-wide distribution of both exogenous and endogenous OGs with high specificity. Our data identified decreased OG occurrence at G-quadruplexes (G4s), in association with underrepresentation of OGs in promoters which have high GC content. Furthermore, we discovered that potential quadruplex sequences (PQSs) were hotspots of OGs, implying a role of non-G4-PQSs in OG-mediated oxidative stress response.

Nanopore Sequencing Accurately Identifies the Cisplatin Adduct on DNA

Cisplatin, which selectively binds to N⁷ atoms of purines to inhibit normal replication and transcription, is a widely applied chemotherapeutic drug in the treatment of cancer. Though direct identification of cisplatin lesions on DNA is of great significance, existing sequencing methods have issues such as complications of preamplification or enrichment-induced false-positive reports. Direct identification of cisplatin lesions by nanopore sequencing (NPS) is in principle feasible. However, relevant investigations have never been reported. By constructing model sequences (83 nucleotides in length) containing a sole cisplatin lesion, identification of corresponding lesions by NPS is achieved with <10 ng of input sequencing library. Moreover, characteristic high-frequency noises caused by cisplatin lesions are consistently observed during NPS, clearly identifiable in corresponding high-pass filtered traces. This feature is, however, never observed in any other combinations of natural DNA bases and could be taken as a reference to identify cisplatin lesions on DNA. Further investigations demonstrate that cisplatin stalls the replication of phi29 DNA polymerase, which appears as a ∼5 pA level fluctuation in the single-molecule resolution. These results have confirmed the feasibility of NPS to identify cisplatin lesions at the genomic level and may provide new insights into understanding the molecular mechanism of platinum-based drugs.

Pharmacological intervention in oxidative stress as a therapeutic target in neurological disorders

OBJECTIVES

Oxidative stress is a major cellular burden that triggers reactive oxygen species (ROS) and antioxidants that modulate signalling mechanisms. Byproducts generated from this process govern the brain pathology and functions in various neurological diseases. As oxidative stress remains the key therapeutic target in neurological disease, it is necessary to explore the multiple routes that can significantly repair the damage caused due to ROS and consequently, neurodegenerative disorders (NDDs). Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is the critical player of oxidative stress that can also be used as a therapeutic target to combat NDDs.

KEY FINDINGS

Several antioxidants signalling pathways are found to be associated with oxidative stress and show a protective effect against stressors by increasing the release of various cytoprotective enzymes and also exert anti-inflammatory response against this oxidative damage. These pathways along with antioxidants and reactive species can be the defined targets to eliminate or reduce the harmful effects of neurological diseases.

SUMMARY

Herein, we discussed the underlying mechanism and crucial role of antioxidants in therapeutics together with natural compounds as a pharmacological tool to combat the cellular deformities cascades caused due to oxidative stress.

Highly sensitive detection of DNA damage in living cells by SERS and electrochemical measurements using a flexible gold nanoelectrode

Guanine (G) oxidation products, such as 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-oxo-guanine (8-OXOG), have been widely studied as promising biomarkers for DNA oxidative damage. In this work, we develop a new method to detect G oxidative products released from live cells after chromium (vi) ion or hydrogen peroxide treatments by using a glass nanopipette-based flexible gold nanoelectrode (fGNE). Specific response to G oxidative products with high sensitivity can be detected from the fGNE tip through integrated electrochemical measurements and surface-enhanced Raman spectroscopy. The fGNE apex can be positioned very close to the cell membrane noninvasively because of its high flexibility and nanoscale tip size. With the assistance of the electrophoretic force, the fGNEs can effectively collect and detect the G-derived DNA damage products released from individual cells in the cell culture medium with high sensitivity.

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.

Biopesticide emamectin benzoate in the liver of male mice: evaluation of oxidative toxicity with stress protein, DNA oxidation, and apoptosis biomarkers

Emamectin benzoate (EMB), which is used as a pesticide in agriculture, household, and veterinary medicine, can cause tissue damage with oxidative toxicity and can be considered as inducing apoptosis. In the present study, male mice were conducted by oral administration in EMB doses 25, 50, and 100 (mg/kg/day) for 14 days. Glutathione (GSH) and thiobarbituric acid reactive substance (TBARS) levels using spectrophotometric methods were measured. 8-hydroxy-2'-deoxyguanosine (8-OHdG) which is DNA oxidation biomarker and, stress protein (HSP70) levels, caspase 3 enzyme activities were measured by ELISA techniques. This study shows that in vivo administration of EMB caused a marked induction of oxidative damage in liver tissue as demonstrated by an increased level of TBARS and reduced GSH level. The increase in HSP70 level did not prevent the apoptosis caused by the increase of caspase 3 enzyme activity. Toxicity caused by EMB also showed the formation of genotoxicity with an increase in DNA oxidation biomarker 8-OHdG levels. As a result of the study, the effects of toxicity caused by EMB on lipid; protein; and DNA, structural macromolecules in cells, and the importance of enzymatic and non-enzymatic bonds of the cell's protective systems were determined. Consequently, under experimental conditions, EMB exposure caused toxicity in the liver of male mice, and significant adverse effects were determined with biomarkers.

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

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

Organic small molecule for detection and photodegradation of mitochondrial DNA mutations

A detection and degradation platform was developed to optically quantify the 6-enolate, 8-keto-dG, an important tautomer of mitochondrial mutated DNA 8-oxo-dG. We first found that 6-enolate, 8-keto-dG offers particular fluorescence emission under the conditions between pH ∼ 7 and ∼11. Thus, a mitochondria-targeting photosensitizer NV-12P was prepared to offer simultaneously photoinduced electron transfer and fluorescence resonance energy transfer (FRET) with 6-enolate, 8-keto-dG. Furthermore, NV-12P can also generate a reactive oxygen species to degrade 6-enolate, 8-keto-dG under irradiation conditions. This is the first publication about optical characterization, concentration detection and photodegradation of 6-enolate, 8-keto-dG, either in biological or in vitro applications.

Ursolic Acid Treatment Alleviates Diabetic Kidney Injury By Regulating The ARAP1/AT1R Signaling Pathway

PURPOSE

This study aimed to investigate whether ursolic acid (UA) mitigates renal inflammation, oxidative stress and fibrosis by regulating the angiotensin II type 1 receptor-associated protein (ARAP1)/angiotensin II type 1 receptor (AT1R) signaling pathway and subsequently alleviating renal damage.

METHODS

db/db mice were divided randomly into a diabetic nephropathy (DN) group and a UA treatment group. Light microscopy and electron microscopy were used to observe pathological changes in renal tissues. Immunohistochemistry (IHC) was employed to examine changes in the expression of ARAP1, AT1R, 8-hydroxydeoxyguanosine (8-OHdG), NADPH oxidase 2 (NOX2), the extracellular matrix protein fibronectin (FN), IL-1β and IL-18 in renal tissues. Western blotting and RT-qPCR were used to detect the respective changes in the protein and mRNA levels of ARAP1, AT1R, NOX4, NOX2, transforming growth factor-β1 (TGF-β1), FN, collagen IV, IL-1β and IL-18 in renal tissues and mesangial cells. In addition, immunofluorescence staining was employed to examine changes in FN and NOX2 expression in mesangial cells.

RESULTS

UA treatment effectively reduced the body weights and blood glucose levels of db/db mice (p<0.05) as well as the urinary albumin/creatinine ratio (p<0.05). In addition, the renal tissue lesions and glomerulosclerosis index of the db/db mice were significantly improved after treatment (p<0.01). Histochemical analysis results showed significantly lower expression levels of ARAP1, AT1R, FN, NOX2, 8-OHdG, IL-1β and IL-18 in renal tissues in the UA treatment group than in the DN group. Western blotting and RT-qPCR data also revealed UA-induced decreases in the renal levels of the ARAP1, AT1, NOX4, NOX2, TGF-β1, FN, collagen IV, IL-1β and IL-18 proteins in vivo and/or in vitro (p<0.01). ARAP1 knockdown effectively reduced the expression of NOX2 and FN in vitro.

CONCLUSION

UA alleviated renal damage in type 2 diabetic db/db mice by downregulating proteins in the ARAP1/AT1R signaling pathway to inhibit extracellular matrix accumulation, renal inflammation, fibrosis and oxidative stress.

Assessment of 8-hydroxy-2-deoxyguanosine activity, gene expression and antioxidant enzyme activity on rainbow trout (Oncorhynchus mykiss) tissues exposed to biopesticide

The goal of this study was to determinate toxicity mechanism of biopesticide with antioxidant enzymes parameters such as superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) and malondialdehyde (MDA) levels, oxidative DNA damage (8-hydroxy-2-deoxyguanosine (8-OHdG)), transcriptional changes of heat shock protein 70 (HSP70), and cytochromes P4501A (CYP1A), sod, cat, and gpx in liver and gill tissues of Oncorhynchus mykiss. For this aim, plant-based (natural pesticides, azadirachtin (AZA)) and synthetic pesticides (deltamethrin (DLM)) were exposed on the fish at different concentrations (0.0005 and 0.00025ppm of DLM; 0.24 and 0.12ppm of AZA) for 21 days. According to the results of the study, the activity of SOD, CAT and GPx decreased, but malondialdehyde (MDA) level and activity of 8-OHdG increased in the gill and liver of rainbow trout (p<0.05). Additionally sod, cat and gpx were down regulated; HSP70 and CYP1A were up regulated for transcriptional observation. The downwards regulation of antioxidant (sod, cat and gpx) and the upregulation of HSP70 and CYP1A was obvious with doses of AZA or DLM (p<0.05). The findings of this study suggest that biopesticide can cause biochemical and physiological effects in the fish gill and liver by causing enzyme inhibition, an increase in 8-OHdG levels and changes in both transcriptional parameters (sod, cat, gpx, HSP70 and CYP1A). We found that excessive doses of plant-based pesticide are nearly as toxic as chemical ones for aquatic organisms. Moreover, 8-OHdG, HSP70 and CYP1A used as a biomarker to determinate toxicity mechanism of biopesticide in aquatic environment.

Investigation of 8-OHdG, CYP1A, HSP70 and transcriptional analyses of antioxidant defence system in liver tissues of rainbow trout exposed to eprinomectin

Eprinomectin (EPM), a member of avermectin family, is a semi-synthetic antibiotic. It has been known that avermectin family enters the aquatic environments and adversely affects the aquatic organisms. Effects of EPM is fully unknown in aquatic organisms especially fish, thus the aim of the present study was to investigate transcriptional changes (sod, cat, gpx) and activities of some antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) and malondialdehyde (MDA) levels, oxidative DNA damage (8-hydroxy-2-deoxyguanosine (8-OHdG)) and transcriptional changes of heat shock protein 70 (HSP70), and cytochromes P4501A (CYP1A) in liver tissues of rainbow trout exposed to sublethal EPM concentration (0.001 μg/L, 0.002 μg/L, 0.01 μg/L, 0.05 μg/L) for 24 h, 48 h, 72 h and 96 h. The decrease in antioxidant enzyme (SOD, CAT and GPx) activity, transcriptional changes (sod, cat, gpx, HSP70 and CYP1A genes) and increase in MDA level and activity of 8-OHdG in a dose-time-dependent manner in the liver of rainbow trout were observed. The down-regulated of antioxidant (sod, cat and gpx), HSP70 and CYP1A obviously, the severity of which increased with the concentration of EPM and exposure time. The results imply that EPM could induce oxidative damage to the liver tissue of rainbow trout. The information presented in this study is helpful to understand the mechanism of veterinary pharmaceuticals-induced oxidative stress in fishes.

Neurotoxic responses in brain tissues of rainbow trout exposed to imidacloprid pesticide: Assessment of 8-hydroxy-2-deoxyguanosine activity, oxidative stress and acetylcholinesterase activity

The extensive use of imidacloprid, a neonicotinoid insecticide, causes undesirable toxicity in non-targeted organisms including fish in aquatic environments. We investigated neurotoxic responses by observing 8-hydroxy-2-deoxyguanosine (8-OHdG) activity, oxidative stress and acetylcholinesterase (AChE) activity in rainbow trout brain tissue after 21 days of imidacloprid exposure at levels of (5 mg/L, 10 mg/L, 20 mg/L). The obtained results indicated that 8-OHdG activity did not change in fish exposed to 5 mg/L of imidacloprid, but 10 mg/L and 20 mg/L of imidacloprid significantly increased 8-OHdG activity compared to the control (p < 0.05). An immunopositiv reaction to 8-OHdG was detected in brain tissues. The brain tissues indicated a significant increase in antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)) compared to the control and there was a significant increase in malondialdehyde (MDA) levels (p < 0.05). High concentrations of imidacloprid caused a significant decrease in AChE enzyme activity (p < 0.05). These results suggested that imidacloprid can be neurotoxic to fish by promoting AChE inhibition, an increase in 8-OHdG activity and changes in oxidative stress parameters. Therefore, these data may reflect one of the molecular pathways that play a role in imidacloprid toxicity.

8-Hydroxy-2-deoxyguanosine levels and heart failure: A systematic review and meta-analysis of the literature

BACKGROUND AND AIMS

The generation of reactive oxygen species (ROS) plays an important role in the etiology of several pathological conditions. High levels of 8-hydroxy-2-deoxyguanosine (8-OHdG), a biomarker of oxidative damage of DNA, have been found in patients with heart failure (HF). We performed a meta-analysis of the literature to investigate the association between 8-OHdG levels and HF.

METHODS AND RESULTS

A systematic search was performed in the PubMed, Web of Science, Scopus, EMBASE databases and studies evaluating 8-OHdG levels in HF patients and controls were included. Differences between cases and controls were expressed as standard mean difference (SMD) or mean difference (MD) with pertinent 95% confidence intervals (95%CI). Impact of clinical and demographic features on effect size was assessed by meta-regression. Six studies (446 HF patients and 140 controls) were included in the analysis. We found that HF patients showed higher 8-OHdG levels than controls (SMD:0.89, 95%CI: 0.68, 1.10). The difference was confirmed both in studies in which 8-OHdG levels were assessed in urine (MD:6.28 ng/mg creatinine, 95%CI: 4.01, 8.56) and in blood samples (MD:0.36 ng/ml, 95%CI: 0.04, 0.69). Interestingly, 8-OHdG levels progressively increased for increasing New York Heart Association (NYHA) class. Meta-regression models showed that none of clinical and demographic variables impacted on the difference in 8-OHdG levels among HF patients and controls.

CONCLUSIONS

8-OHdG levels are higher in HF patients HF than in controls, with a progressive increase for increasing NYHA class. However, larger prospective studies are needed to test 8-OHdG as a biomarker of HF severity and progression.

Measurement of Reactive Oxygen Species, Reactive Nitrogen Species, and Redox-Dependent Signaling in the Cardiovascular System: A Scientific Statement From the American Heart Association

Reactive oxygen species and reactive nitrogen species are biological molecules that play important roles in cardiovascular physiology and contribute to disease initiation, progression, and severity. Because of their ephemeral nature and rapid reactivity, these species are difficult to measure directly with high accuracy and precision. In this statement, we review current methods for measuring these species and the secondary products they generate and suggest approaches for measuring redox status, oxidative stress, and the production of individual reactive oxygen and nitrogen species. We discuss the strengths and limitations of different methods and the relative specificity and suitability of these methods for measuring the concentrations of reactive oxygen and reactive nitrogen species in cells, tissues, and biological fluids. We provide specific guidelines, through expert opinion, for choosing reliable and reproducible assays for different experimental and clinical situations. These guidelines are intended to help investigators and clinical researchers avoid experimental error and ensure high-quality measurements of these important biological species.

8-Hydroxy-2-Deoxyguanosine Levels and Cardiovascular Disease: A Systematic Review and Meta-Analysis of the Literature

SIGNIFICANCE

8-Hydroxy-2-deoxyguanosine (8-OHdG) is generated after the repair of ROS-mediated DNA damages and, thus, is one of the most widely recognized biomarkers of oxidative damage of DNA because guanosine is the most oxidized among the DNA nucleobases. In several pathological conditions, high urinary levels of oxidized DNA-derived metabolites have been reported (e.g., cancer, atherosclerosis, hypertension, and diabetes).

RECENT ADVANCES

Even if published studies have shown that DNA damage is significantly associated with the development of atherosclerosis, the exact role of this damage in the onset and progression of this pathology is not fully understood, and the association of oxidative damage to DNA with cardiovascular disease (CVD) still needs to be more extensively investigated. We performed a meta-analysis of the literature to investigate the association among 8-OHdG levels and CVD.

CRITICAL ISSUES

Fourteen studies (810 CVD patients and 1106 controls) were included in the analysis. We found that CVD patients showed higher 8-OHdG levels than controls (SMD: 1.04, 95%CI: 0.61, 1.47, p < 0.001, I(2) = 94%, p < 0.001). The difference was confirmed both in studies in which 8-OHdG levels were assessed in urine (MD: 4.43, 95%CI: 1.71, 7.15, p = 0.001) and in blood samples (MD: 1.42, 95%CI: 0.64, 2.21, p = 0.0004). Meta-regression models showed that age, hypertension, and male gender significantly impacted on the difference in 8-OHdG levels among CVD patients and controls.

FUTURE DIRECTIONS

8-OHdG levels are higher in patients with CVD than in controls. However, larger prospective studies are needed to test 8-OHdG as a predictor of CVD.

Silencing PRDX3 Inhibits Growth and Promotes Invasion and Extracellular Matrix Degradation in Hepatocellular Carcinoma Cells

PRDX3 is a mitochondrial peroxide reductase that regulates cellular redox state. It has been reported that PRDX3 is overexpressed in liver cancer, but how PRDX3 is involved in hepatocellular carcinoma (HCC) tumorigenesis and progression has not been well-characterized. In the present study, we established two stable cell lines by overexpressing or knocking down PRDX3 in HepG2 cells. We found that PRDX3 silencing decreased the growth rate of HepG2 cells and increased mtDNA oxidation. Quantitative proteomics identified 475 differentially expressed proteins between the PRDX3 knockdown and the control cells. These proteins were involved in antioxidant activity, angiogenesis, cell adhesion, cell growth, ATP synthesis, nucleic acid binding, redox, and chaperones. PRDX3 knockdown led to the down-regulation of ATP synthases and the decreased cellular ATP level, contributing to the slow-down of cell growth. Furthermore, silencing PRDX3 enhanced invasive properties of HepG2 cells via TIMP-1 down-regulation and the increased ECM degradation. Taken together, our results indicate that PRDX3 promotes HCC growth and mediates cell migration and invasiveness and is a potential therapeutic target for HCC treatment.

In vitro study of the effect of metabolism enzymes on benzo(a)pyrene-induced DNA damage in the scallop Chlamys farreri

Acute toxicity effect of benzo(a)pyrene (BaP) on isolated scallop (Chlamys farreri) digestive gland cells was studied and a dose-dependent increase in toxicity was observed. The 8 μg/L of BaP had a significant toxic effect on isolated cells (p<0.05). In order to study the mechanism of CYP450, GST, SOD and MXR transporters involved in the production of DNA strand breakage such as DNA adduct formation and oxidative DNA damage by BaP were investigated in isolated digestive gland cells. Isolated cells were exposed in vitro to 0.8 μg/L of BaP for 24h in the dark at 25 °C in the absence or presence of cytochrome P450 inhibitor, GST inhibitor, Pgp inhibitor and antioxidant enzyme inhibitor. DNA adduct and 8-OHdG content were measured using the Enzyme-linked Immunosorbent Assay. The result indicated that DNA strand breakage was increased to 2 times compared with the control in the 0.8 μg/L of BaP treatment groups. The BaP-induced DNA adduct and 8-OHdG content increased significantly by inhibiting GST, while only 8-OHdG increased significantly when SOD was inhibited. The content of DNA adduct and 8-OHdG had no significant change when CYP450 was inhibited, while it decreased significantly when MXR transporters were inhibited. The result proved that GST play a key role in eliminating the BaP-induced DNA adduct and 8-OHdG, and SOD also had an important function in reducing the production of BaP-induced 8-OHdG.

Electrochemical investigations of 8-hydroxydeoxyguanosine and its determination at an edge plane pyrolytic graphite electrode

Electrochemical oxidation of 8-hydroxydeoxyguanosine (8-OHdG) and its detection with low detection limit is reported at pyrolytic graphite electrode.

High sensitivity detection of salivary 8-hydroxy deoxyguanosine levels in patients with chronic periodontitis

BACKGROUND

Inflammation is associated with hydroxyl radical damage to DNA as a result of oxidative stress. 8-Hydroxy deoxyguanosine (8-OHdG) is a marker of this process and its levels in saliva could be linked to the severity of periodontal inflammation. The aim of this study was to test the sensitivity of liquid chromatography with tandem mass spectrometry (LC-MS/MS) in comparison to enzyme-linked immune sorbent assay (ELISA) for the detection of 8-OHdG in saliva in patients with chronic periodontitis before and after periodontal treatment.

METHODS

Saliva samples were collected from 23 patients (eight females and 15 males; 46.1 ± 5.1 years of age) with generalized chronic periodontitis and 25 (15 females and 10 males; 44.9 ± 6.8 years of age) periodontally healthy individuals. Patients received initial periodontal treatment consisting of scaling and root planing and were evaluated at baseline and after 6 wk of completion of non-surgical therapy. Salivary 8-OHdG levels were measured using ELISA and LC-MS/MS before and after the treatment. Clinically, plaque index, gingival index, clinical attachment level, bleeding on probing, gingival recession and probing pocket depth were measured at baseline and after 6 wk.

RESULTS

Salivary levels of 8-OHdG decreased significantly after the non-surgical periodontal treatment (p < 0.001). Statistically significant positive correlations were observed between plaque index, gingival index, probing pocket depth, clinical attachment level, bleeding on probing values and LC-MS/MS and ELISA levels of 8-OHdG (p < 0.001).

CONCLUSION

LC-MS/MS is a reliable and sensitive method for evaluating salivary 8-OHdG levels to monitor the treatment response of periodontitis.

An active role for the ribosome in determining the fate of oxidized mRNA

Chemical damage to RNA affects its functional properties and thus may pose a significant hurdle to the translational apparatus; however, the effects of damaged mRNA on the speed and accuracy of the decoding process and their interplay with quality-control processes are not known. Here, we systematically explore the effects of oxidative damage on the decoding process using a well-defined bacterial in vitro translation system. We find that the oxidative lesion 8-oxoguanosine (8-oxoG) reduces the rate of peptide-bond formation by more than three orders of magnitude independent of its position within the codon. Interestingly, 8-oxoG had little effect on the fidelity of the selection process, suggesting that the modification stalls the translational machinery. Consistent with these findings, 8-oxoG mRNAs were observed to accumulate and associate with polyribosomes in yeast strains in which no-go decay is compromised. Our data provide compelling evidence that mRNA-surveillance mechanisms have evolved to cope with damaged mRNA.

Role of Bacillus subtilis error prevention oxidized guanine system in counteracting hexavalent chromium-promoted oxidative DNA damage

Chromium pollution is potentially detrimental to bacterial soil communities, compromising carbon and nitrogen cycles that are essential for life on earth. It has been proposed that intracellular reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] may cause bacterial death by a mechanism that involves reactive oxygen species (ROS)-induced DNA damage; the molecular basis of the phenomenon was investigated in this work. Here, we report that Bacillus subtilis cells lacking a functional error prevention oxidized guanine (GO) system were significantly more sensitive to Cr(VI) treatment than cells of the wild-type (WT) strain, suggesting that oxidative damage to DNA is involved in the deleterious effects of the oxyanion. In agreement with this suggestion, Cr(VI) dramatically increased the ROS concentration and induced mutagenesis in a GO-deficient B. subtilis strain. Alkaline gel electrophoresis (AGE) analysis of chromosomal DNA of WT and ΔGO mutant strains subjected to Cr(VI) treatment revealed that the DNA of the ΔGO strain was more susceptible to DNA glycosylase Fpg attack, suggesting that chromium genotoxicity is associated with 7,8-dihydro-8-oxodeoxyguanosine (8-oxo-G) lesions. In support of this notion, specific monoclonal antibodies detected the accumulation of 8-oxo-G lesions in the chromosomes of B. subtilis cells subjected to Cr(VI) treatment. We conclude that Cr(VI) promotes mutagenesis and cell death in B. subtilis by a mechanism that involves radical oxygen attack of DNA, generating 8-oxo-G, and that such effects are counteracted by the prevention and repair GO system.

α-Tocopherol supplementation reduces biomarkers of oxidative stress in children with Down syndrome: a randomized controlled trial

BACKGROUND

Down syndrome (DS) is the most common human chromosomal abnormality. It is characterized by mental retardation and several metabolic disturbances, including elevated oxidative stress, which may be causally linked. Treatment with dietary antioxidants has been suggested as a potential method to alleviate the oxidative damage and retardation of DS patients, but prior supplementation work has been equivocal.

AIM

To evaluate the effects of supplementation with antioxidants α-tocopherol and α-lipoic acid (ALA) on oxidative stress biomarkers in DS children.

METHODS

Ninety-three DS children aged 7-15 years from both sexes were randomly allocated to three groups: α-tocopherol (400 IU/day), ALA (100 mg/day) and placebo. The intervention period was 4 months. A healthy control group consisted 26 non-DS siblings. Serum thiobarbituric acid reactive substances (TBARS) and urinary 8-hydroxy-2'-deoxyguanosine (8OHdG) were used as biomarkers of oxidative stress.

RESULTS

DS children had greater levels of baseline oxidative stress than their siblings. Moreover, males had greater levels of 8OHdG than females (P<0.001) but there was no significant association between age and biomarkers of oxidative stress. Serum levels of TBARS did not change significantly over time, or relative to placebo. Although urinary 8OHdG concentrations decreased significantly in both α-tocopherol and ALA, groups compared with the baseline levels (P<0.001), mean final levels of urinary 8OHdG concentrations differed significantly only between α-tocopherol and placebo groups (P<0.01).

CONCLUSIONS

α-Tocopherol supplementation of the diets of DS children may attenuate oxidative stress at the DNA level.

Oxidative stress of office workers relevant to tobacco smoking and inner air quality

Studies have used 8-hydroxydeoxyguanosine (8-OHdG) as a biomarker to detect systemic oxidative DNA damage associated with oxidative stress. However, studies on the association between exposure to tobacco smoking and urinary 8-OHdgG give inconsistent results. Limited studies have estimated the oxidative stress among office workers. This study assessed the association between urinary 8-OHdG and cotinine for office workers. Workers (389) including smokers, ex-smokers and non-smokers from 87 offices at high-rise buildings in Taipei participated in this study with informed consent. Each participant completed a questionnaire and provided a spot urine specimen at the end of work day for measuring urinary 8-OHdG and cotinine. The carbon dioxide (CO₂) levels in workers’ offices were also measured. The questionnaire reported socio-demographic characteristics, life styles and allergic history. The urinary 8-OHdG level increased with the cotinine level among participants (Spearmans’ rho = 0.543, p < 0.001). The mean of urinary 8-OHdG and cotinine was 5.81 ± 3.53 μg/g creatinine and 3.76 ± 4.06 μg/g creatinine, respectively. Comparing with non-smokers, the adjusted odds ratio (OR) of having urinary 8-OHdG greater than the median level of 4.99 μg/g creatinine was 5.30 (95% confidence intervals (CI) = 1.30–21.5) for current smokers and 0.91 (95% CI = 0.34–2.43) for former smokers. We also found workers exposed to 1,000 ppm of CO₂ at offices had an adjusted OR of 4.28 (95% CI = 1.12–16.4) to have urinary 8-OHdG greater than 4.99 μg/g creatinine, compared to those exposed to indoor CO₂ under 600 ppm. In conclusion, urinary 8-OHdG could represent a suitable marker for measuring smoking and CO₂ exposure for office workers.

Voltammetric microwell array for oxidized guanosine in intact ds-DNA

Oxidative stress in humans causes damage to biomolecules by generating reactive oxygen species (ROS). DNA can be oxidatively damaged by ROS, which may lead to carcinogenesis. Here we report a microfluidic electrochemical array designed to rapidly detect oxidation in intact DNA in replicate measurements. Sensor arrays were fabricated by wet-chemistry patterning of gold compact discs. The eight-sensor array is incorporated into a 60 μL microfluidic channel connected to a pump and sample valve. The array features 7 nm thick osmium bipyridyl poly(vinylpyridine) chloride [Os(bpy)2(PVP)10Cl](+) films assembled layer-by-layer with polyions onto the gold sensors. 8-Hydroxy-7,8-hydro-2'-deoxyguanosine (8-oxodG) is selectively oxidized by [Os(bpy)2(PVP)10Cl](+) in intact ds-DNA to provide catalytic square wave voltammograms (SWV). The device is easy-to-use, fast, inexpensive, reusable, and can detect one 8-oxodG per 6600 nucleobases. The mass detection limit is 150-fold lower than a previously reported dip-and-read voltammetric sensor for oxidized DNA. Fast assays (<1 min) and moderate sample consumption (15 pmol DNA) suggest potential for research and clinical applications. Practical use is illustrated by detecting DNA oxidation from cigarette smoke and ash extracts in dispersions with NADPH and Cu(2+).

Methionine restriction affects oxidative stress and glutathione-related redox pathways in the rat

Lifelong dietary methionine restriction (MR) is associated with increased longevity and decreased incidence of age-related disorders and diseases in rats and mice. A reduction in the levels of oxidative stress may be a contributing mechanistic factor for the beneficial effects of MR. To examine this, we determined the effects of an 80% dietary restriction of Met on different biomarkers of oxidative stress and antioxidant pathways in blood, liver, kidney and brain in the rat. Male F-344 rats were fed control (0.86% methionine) or MR (0.17% methionine) diets for up to six months. Blood and tissues were analyzed for glutathione (GSH) concentrations, related enzyme activities and biomarkers of oxidative stress. MR was associated with reductions in oxidative stress biomarkers including plasma 8-hydoxydeoxyguanosine (8-OHdG) and 8-isoprostane and erythrocyte protein-bound glutathione after one month with levels remaining low for at least six months (P < 0.05). Levels of free GSH in blood were increased after 1-6 months of MR feeding whereas liver GSH levels were reduced over this time (P < 0.05). In MR rats, GSH peroxidase activity was decreased in liver and increased in kidney compared with controls. No changes in the activities of GSH reductase in liver and kidney and superoxide dismutase in liver were observed as a result of MR feeding. Altogether, these findings indicate that oxidative stress is reduced by MR feeding in rats, but this effect cannot be explained by changes in the activity of antioxidant enzymes.

Detection and quantification of 8-hydroxy-2'-deoxyguanosine in Alzheimer's transgenic mouse urine using capillary electrophoresis

8-Hydroxy-2'-deoxyguanosine (8-OHdG) is one of the major forms of oxidative DNA damage, and is commonly analyzed as an excellent marker of DNA lesions. The purpose of this study was to develop a sensitive method to accurately and rapidly quantify the 8-OHdG by using CE-LIF detection. The method involved the use of specific antibody to detect the DNA lesion (8-OHdG) and consecutive fluorescence labeling. Next, urinary 8-OHdG fluorescently labeled along with other constituents were resolved by capillary electrophoretic system and the lesion of interest was detected using a fluorescence detector. The limit of detection was 0.18 fmol, which proved sufficient sensitivity for detection and quantification of 8-OHdG in untreated urine samples. The relative standard deviation was found to be 11.32% for migration time and 5.52% for peak area. To demonstrate the utility of this method, the urinary concentration of 8-OHdG in an Alzheimer's transgenic mouse model was determined. Collectively, our results indicate that this methodology offers great advantages, such as high separation efficiency, good selectivity, low limit of detection, simplicity and low cost of analysis.

Human and methodological sources of variability in the measurement of urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine

AIMS

Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is a widely used biomarker of oxidative stress. However, variability between chromatographic and ELISA methods hampers interpretation of data, and this variability may increase should urine composition differ between individuals, leading to assay interference. Furthermore, optimal urine sampling conditions are not well defined. We performed inter-laboratory comparisons of 8-oxodG measurement between mass spectrometric-, electrochemical- and ELISA-based methods, using common within-technique calibrants to analyze 8-oxodG-spiked phosphate-buffered saline and urine samples. We also investigated human subject- and sample collection-related variables, as potential sources of variability.

RESULTS

Chromatographic assays showed high agreement across urines from different subjects, whereas ELISAs showed far more inter-laboratory variation and generally overestimated levels, compared to the chromatographic assays. Excretion rates in timed 'spot' samples showed strong correlations with 24 h excretion (the 'gold' standard) of urinary 8-oxodG (rp 0.67-0.90), although the associations were weaker for 8-oxodG adjusted for creatinine or specific gravity (SG). The within-individual excretion of 8-oxodG varied only moderately between days (CV 17% for 24 h excretion and 20% for first void, creatinine-corrected samples).

INNOVATION

This is the first comprehensive study of both human and methodological factors influencing 8-oxodG measurement, providing key information for future studies with this important biomarker.

CONCLUSION

ELISA variability is greater than chromatographic assay variability, and cannot determine absolute levels of 8-oxodG. Use of standardized calibrants greatly improves intra-technique agreement and, for the chromatographic assays, importantly allows integration of results for pooled analyses. If 24 h samples are not feasible, creatinine- or SG-adjusted first morning samples are recommended.

Development of immunoblotting techniques for DNA radical detection

Radical damage to DNA has been implicated in cell death, cellular dysfunction, and cancer. A recently developed method for detecting DNA radicals uses the nitrone spin trap DMPO (5,5-dimethyl-1-pyrroline N-oxide) to trap radicals. The trapped radicals then decay into stable nitrone adducts detectable with anti-DMPO antibodies and quantifiable by ELISA or dot-blot assay. However, the sequences of DNA that are damaged are likely to be as important as the total level of damage. Therefore, we have developed immunoblotting methods for detection of DNA nitrone adducts on electrophoretically separated DNA, comparable to Western blotting for proteins. These new techniques not only allow the assessment of relative radical adduct levels, but can reveal specific DNA fragments, and ultimately nucleotides, as radical targets. Moreover, we have determined that denaturation of samples into single-stranded DNA enhances the detection of DNA-DMPO adducts in our new blotting methods and also in ELISA.

Markers of oxidant stress that are clinically relevant in aging and age-related disease

Despite the long held hypothesis that oxidant stress results in accumulated oxidative damage to cellular macromolecules and subsequently to aging and age-related chronic disease, it has been difficult to consistently define and specifically identify markers of oxidant stress that are consistently and directly linked to age and disease status. Inflammation because it is also linked to oxidant stress, aging, and chronic disease also plays an important role in understanding the clinical implications of oxidant stress and relevant markers. Much attention has focused on identifying specific markers of oxidative stress and inflammation that could be measured in easily accessible tissues and fluids (lymphocytes, plasma, serum). The purpose of this review is to discuss markers of oxidant stress used in the field as biomarkers of aging and age-related diseases, highlighting differences observed by race when data is available. We highlight DNA, RNA, protein, and lipid oxidation as measures of oxidative stress, as well as other well-characterized markers of oxidative damage and inflammation and discuss their strengths and limitations. We present the current state of the literature reporting use of these markers in studies of human cohorts in relation to age and age-related disease and also with a special emphasis on differences observed by race when relevant.

Polyphenol-rich foods exhibit DNA antioxidative properties and protect the glutathione system in healthy subjects

SCOPE

Polyphenols (ingested via food items) can decrease DNA, and oxidative damage of proteins and lipids. However, polyphenol effects in healthy populations have not been well defined. The aim of this study was to assess the relationship between urinary total polyphenol excretion (TPE), a biomarker of total polyphenol intake (TPI), polyphenol-rich foods, and oxidative stress biomarkers in healthy adults of different ages participating in the cross-sectional PAScual MEDicina study.

METHODS AND RESULTS

Urinary TPE was determined by Folin-Ciocalteau method in spot urine samples of 81 participants (46 women), classified into three age groups: 18 to 39, 40 to 54, and 55 to 72 years of age. TPI was quantified from 3-day dietary records using the Phenol-Explorer database. Urinary TPE increased with age (p < 0.001). Urinary TPE was inversely associated with urinary 8-hydroxydeoxyguanosine (8-OHdG; p<0.001) and erythrocyte-oxidized glutathione concentrations (p < 0.05). A negative association between urinary 8-OHdG and daily intake of polyphenols from vegetables and fermented beverages such as red wine was observed.

CONCLUSION

Urinary TPE increased with age and may reflect attenuation of oxidative damage. These results could explain the beneficial effects in healthy individuals of a diet rich in vegetables and moderate red wine; food items typical of the Mediterranean diet.

Dose-dependency in pleiotropic effects of atorvastatin

Statins are recognized as the principal and most effective class of drugs for reducing serum cholesterol levels and, therefore, significantly reducing cardiovascular events and mortality. Statins may have a wide range of beneficial biological effects in addition to lipid lowering, a phenomenon commonly termed a 'pleiotropic effect'. However, the dose-dependency of these effects remains unclear. The present study evaluated whether atorvastatin, a potent statin, ameliorates the serum markers of pleiotropic effects, with a focus on dose-dependency. The pleiotropic effects of treatment with atorvastatin 5 mg/day and 10 mg/day for six months each in 15 patients with primary hypercholesterolemia were assessed in a prospective, randomized, open-label, crossover, single-centre study. Atorvastatin treatment dose-dependently decreased a serum marker of oxidative stress as well as the serum low-density lipoprotein cholesterol level. However, serum markers of inflammation and fibrinolysis decreased independently of dose. In conclusion, the dose-dependency of atorvastatin's pleiotropic effects differs among individual biological effects.

Increased levels of 8-hydroxy-2'-deoxyguanosine are attributable to organophosphate pesticide exposure among young children

Oxidative damage has been proposed as an important mechanism linking pesticide exposure to health effects. A study of 268 young Shanghai children was conducted to examine the relationship between organophosphate pesticide (OP) exposure and a biomarker of oxidative DNA damage. Urine samples were analyzed for five nonspecific dialkyl phosphate (DAP) metabolites [dimethyl phosphates (DMs) and diethyl phosphates (DEs)] and 8-hydroxy-2'-deoxyguanosine (8-OHdG). The creatinine-adjusted median of 8-OHdG in urine samples was 3.99 ng/mg. Increased exposure to OPs was associated with greater levels of urinary 8-OHdG [total DAPs: ß (adjusted)=0.46 per log(10) unit increase, 95% confidence interval (CI)=0.40-0.53, p=0.000; DMs: ß (adjusted)=0.34, 95% CI=0.28-0.41, p=0.000; DEs: ß (adjusted)=0.48, 95% CI=0.42-0.54, p=0.000]. Thus, the 8-OHdG biomarker is useful for increasing our understanding of the link between childhood exposure to OPs and health outcomes.