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Background: This research aims to evaluate whether polyethylene glycol (PEG), which can immediately repair neuronal membranes, will have a protective effect against radiation-induced brain injury (RIBI). Materials and Methods: Whole brain irradiation (RAD) procedure was performed on 14 of 21 rats included in the study for establishing RIBI. Rats were randomly divided into three groups containing equal numbers of animals: control (RAD not established), placebo (RAD applied, and treated with 1 ml/kg/day of saline that was administered intraperitoneally), and treatment (RAD applied, and treated with 30 mg/kg/day of PEG 3350 that was administered intraperitoneally). Following the end of the 22-day treatments, behavioral tests were performed first, and then magnetic resonance spectroscopy (MRS) was applied to measure brain lactate levels. All rats were sacrificed in order to perform biochemical analysis and histopathological examination of brain tissue. Results: Compared to the control group, MDA, TNF-α, NF-κB and lactate levels were significantly increased, while BDNF levels were decreased in the placebo group; and RAD-induced changes in all these biochemical markers were reversed by PEG. In MRS performed from the corpus striatum, there was an evident decrease in lactate levels after PEG treatment. Impairment in memory and learning was more limited in PEG-treated rats than in the rats receiving saline therapy. Furthermore, histological examinations from hippocampus and cerebellum exhibited that PEG treatment significantly reduces apoptosis, astrogliosis, and oxidative DNA damage in rats. Conclusion: Our results support that PEG is very effective in preventing RIBI with its secondary effects on the basis of membrane stabilization. [ABSTRACT FROM AUTHOR]

8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) is a crucial biomarker of oxidative DNA damage. Herein, a highly sensitive fluorescent aptasensor for detecting 8-oxo-dG in urine was developed based on aptamer-mediated quenching of amino-terminated oligo-(ethylene glycol)-capped gold nanoparticles (NH2-TEG-AuNPs) toward green emissive carbon dots (G-CDs). G-CDs were employed as fluorometric reporters. Upon addition of 8-oxo-dG, it formed a complex with an anti-8-oxo-dG aptamer, resulting in the quenching of fluorescence as NH2-TEG-AuNPs absorbed the emission from G-CDs. Initially, NH2-TEG-AuNPs suppressed the fluorescence intensity of G-CDs via the inner-filter effect (IFE). With the addition of the aptamers to a mixture of G-CDs and NH2-TEG-AuNPs, the electrostatic interactions between the aptamer and NH2-TEG-AuNPs resulted in the aggregation of NH2-TEG-AuNPs and the recovery of the fluorescence intensity of the quenched G-CDs. NH2-TEG-AuNPs dispersed due to the high affinity between the aptamer and 8-oxo-dG molecules, and the system demonstrated a fluorescence ″turn-off″ response of G-CDs. Thus, it was possible to determine the 8-oxo-dG concentration. A fluorescence calibration curve was constructed with two linear ranges: 100–2000 and 2000–10,000 nM. The limit of detection (LOD) for 8-oxo-dG was 15.89 nM. This approach was successfully applied to assess 8-oxo-dG in synthetic urine samples with mean recoveries ranging from 99 to 120% and relative standard deviations (RSDs) between 1.1 and 4.1%. The analytical performance was comparable to a commercially available enzyme-linked immunosorbent assay (ELISA) kit. This proposed fluorescent aptasensor for 8-oxo-dG detection in urine exhibited high selectivity and sensitivity over a broad concentration range against the target molecule and has the potential to be developed as a new platform for rapid screening of 8-oxo-dG. [ABSTRACT FROM AUTHOR]

The genetic information stored in the nucleobase sequence is continuously exposed to harmful extra- and intra-cellular factors, which can lead to different types of DNA damage, with more than 70 lesion types identified so far. In this article, the influence of a multi-damage site containing (5′R/S) 5′,8-cyclo-2′-deoxyguanosine (cdG) and 7,8-dihydro-8-oxo-2′-deoxyguanosine (OXOdG) on charge transfer through ds-DNA was taken into consideration. The spatial geometries of oligo-RcdG: d[A1(5′R)cG2A3OXOG4A5]*d[T5C4T3C2T1] and oligo-ScdG: d[A1(5′S)cG2A3OXOG4A5]*d[T5C4T3C2T1] were optimized at the M06-2X/6-D95**//M06-2X/sto-3G level of theory in the aqueous phase using ONIOM methodology. For all the electronic property energies under discussion, the M06-2X/6-31++G** level of theory was used. Additionally, the non-equilibrated and equilibrated solvent-solute interactions were into consideration. The obtained results confirm the predisposition of OXOdG to radical cation formation regardless of the presence of other lesions in a ds-DNA structure. In the case of electron transfer, however, the situation is different. An excess electron migration towards (5′S)cdG was found to be preferred in the case of oligo-ScdG, while in the case of oligo-RcdG, OXOdG was favored. The above observation was confirmed by the charge transfer rate constant, vertical/adiabatic ionization potential, and electron affinity energy values, as well as the charge and spin distribution analysis. The obtained results indicate that 5′,8-cyclo-2′-deoxyguanosine, depending on the C5′ atom chirality, can significantly influence the charge migration process through the double helix. The above can be manifested by the slowdown of DNA lesion recognition and removal processes, which can increase the probability of mutagenesis and subsequent pathological processes. With regard to anticancer therapy (radio/chemo), the presence of (5′S)cdG in the structure of formed clustered DNA damage can lead to improvements in cancer treatment. [ABSTRACT FROM AUTHOR]

Ionising radiation damages DNA directly and indirectly through increased production of reactive oxygen species. Although telomeres have been reported as indicators of radiosensitivity, their maintenance in response to occupational exposure to low radiation doses is still a matter of debate. In this work we aimed to investigate telomere length and structure in hospital workers occupationally exposed to X-rays and to relate these findings to oxidation of biomolecules and chromosome aberrations. Blood samples of exposed participants and matching controls were taken during periodical check-ups. Chromosome aberrations and telomere length and structure were analysed in peripheral blood lymphocytes using Q-FISH, whereas oxidative stress parameters [pro/antioxidant balance (PAB), lipid peroxidation, and 8-oxo-dG] were measured in plasma samples. Based on the CA findings we divided the exposed group into two subgroups, of which one had chromosome aberrations in the first division metaphases and the other did not. There was no significant difference in telomere length between any of the groups. However, both subgroups showed significantly higher rate of fragile telomeres and higher lipid peroxidation product and 8-oxo-dG levels than controls. The rate of fragile telomeres significantly correlated with plasma levels of 8-oxo-dG, which suggests that continuous exposure to low radiation doses induces oxidative base damage of guanine resulting in telomere fragility.

Mitochondrial (mt) DNA and nuclear (n) DNA have known structures and roles in cells; however, they are rarely compared under specific conditions such as oxidative or degenerative environments that can create damage to the DNA base moieties. Six purine lesions were ascertained in the mtDNA of wild type (wt) CSA (CS3BE–wtCSA) and wtCSB (CS1AN–wtCSB) cells and defective counterparts CS3BE and CS1AN in comparison with the corresponding total (t) DNA (t = n + mt). In particular, the four 5′,8–cyclopurine (cPu) and the two 8–oxo–purine (8–oxo–Pu) lesions were accurately quantified by LC–MS/MS analysis using isotopomeric internal standards after an enzymatic digestion procedure. The 8–oxo–Pu levels were found to be in the range of 25–50 lesions/107 nucleotides in both the mtDNA and tDNA. The four cPu were undetectable in the mtDNA both in defective cells and in the wt counterparts (CSA and CSB), contrary to their detection in tDNA, indicating a nonappearance of hydroxyl radical (HO•) reactivity within the mtDNA. In order to assess the HO• reactivity towards purine nucleobases in the two genetic materials, we performed γ–radiolysis experiments coupled with the 8–oxo–Pu and cPu quantifications on isolated mtDNA and tDNA from wtCSB cells. In the latter experiments, all six purine lesions were detected in both of the DNA, showing a higher resistance to HO• attack in the case of mtDNA compared with tDNA, likely due to their different DNA helical topology influencing the relative abundance of the lesions. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the ocular distribution and plasma pharmacokinetics (PKs) of 8-oxo-2'-deoxyguanosine (8-oxo-dG) in rabbits and rats, respectively. Methods: A test formulation containing radiolabeled [14 C]8-oxo-dG and unlabeled 8-oxo-dG was ocularly administered to rabbits as a single dose of 1 mg per body and intravenously injected to rats as a single dose of 5 mg/kg. The ocular distribution of [14 C]8-oxo-dG was evaluated using autoradiography until 48 h postdose. Plasma radioactivity in rabbits and rats was determined until 72 and 168 h, respectively. Results: After ocular instillation, [14 C]8-oxo-dG distributed into ocular tissues, and high radioactivity concentrations were observed in the ciliary body, conjunctiva, and cornea. The maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC0-t) were highest in the ciliary body and conjunctiva, respectively. In the conjunctiva, cornea, and aqueous humor, time to reach Cmax (Tmax) was 0.5 h, and the half-lives were 11.2, 30.2, and 15.1 h, respectively. The radioactivity of [14 C]8-oxo-dG in plasma of rabbits displayed a double-peak phenomenon with the second peak considered as Cmax (37.9 ± 3.1 ng eq./mL) occurring 24 h postdose. After systemic exposure of [14 C]8-oxo-dG in rats, a rapid decline in the initial phase and a terminal half-life of 56.1 ± 31.3 h were observed. Conclusions: Rapid ocular distribution and high concentrations in anterior ocular tissues with minimal systemic exposure were observed after the ocular instillation of 8-oxo-dG in rabbits. These PK profiles are favorable for the treatment of ocular surface diseases. [ABSTRACT FROM AUTHOR]

The functional derangement affecting human chondrocytes during osteoarthritis (OA) onset and progression is sustained by the failure of major homeostatic mechanisms. This makes them more susceptible to oxidative stress (OS), which can induce DNA damage responses and exacerbate stress-induced senescence. The knockdown (KD) of IκB kinase α (IKKα), a dispensable protein in healthy articular cartilage physiology, was shown to increase the survival and replication potential of human primary OA chondrocytes. Our recent findings showed that the DNA Mismatch Repair pathway only partially accounts for the reduced susceptibility to OS of IKKαKD cells. Here we therefore investigated other ROS-mediated DNA damage and repair mechanisms. We exposed IKKαWT and IKKαKD chondrocytes to sub-cytotoxic hydrogen peroxide and evaluated the occurrence of double-strand breaks (DSB), 8-oxo-2'-deoxyguanosine (8-oxo-dG) and telomere shortening. ROS exposure was able to significantly increase the number of γH2AX foci (directly related to the number of DSB) in both cell types, but IKKα deficient cells undergoing cell division were able to better recover compared to their IKKα proficient counterpart. 8-oxo-dG signal proved to be the highest DNA damage signal among those investigated, located in the mitochondria and with a slightly higher intensity in IKKα proficient cells immediately after OS exposure. Furthermore, ROS significantly reduced telomere length both in IKKαWT and IKKαKD, with the former showing more pervasive effects, especially in dividing cells. Assessment of the HIF-1α>Beclin-1>LC3B axis after recovery from OS showed that IKKα deficient cells exhibited a more efficient autophagic machinery that allowed them to better cope with oxidative stress, possibly through the turnover of damaged mitochondria. Higher Beclin-1 levels likely helped in rescuing dividing cells (identified by coupled cell cycle analysis) because of Beclin-1's involvement in both autophagy and mitotic spindle organization. Therefore, our data further confirm the higher capacity of IKKαKD chondrocytes to cope with oxidative stress-induced DNA damage., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The genetic information stored in the nucleobase sequence is continuously exposed to harmful extra- and intra-cellular factors, which can lead to different types of DNA damage, with more than 70 lesion types identified so far. In this article, the influence of a multi-damage site containing (5′R/S) 5′,8-cyclo-2′-deoxyguanosine (cdG) and 7,8-dihydro-8-oxo-2′-deoxyguanosine (OXOdG) on charge transfer through ds-DNA was taken into consideration. The spatial geometries of oligo-RcdG: d[A1(5′R)cG2A3OXOG4A5]*d[T5C4T3C2T1] and oligo-ScdG: d[A1(5′S)cG2A3OXOG4A5]*d[T5C4T3C2T1] were optimized at the M06-2X/6-D95**//M06-2X/sto-3G level of theory in the aqueous phase using ONIOM methodology. For all the electronic property energies under discussion, the M06-2X/6-31++G** level of theory was used. Additionally, the non-equilibrated and equilibrated solvent-solute interactions were into consideration. The obtained results confirm the predisposition of OXOdG to radical cation formation regardless of the presence of other lesions in a ds-DNA structure. In the case of electron transfer, however, the situation is different. An excess electron migration towards (5′S)cdG was found to be preferred in the case of oligo-ScdG, while in the case of oligo-RcdG, OXOdG was favored. The above observation was confirmed by the charge transfer rate constant, vertical/adiabatic ionization potential, and electron affinity energy values, as well as the charge and spin distribution analysis. The obtained results indicate that 5′,8-cyclo-2′-deoxyguanosine, depending on the C5′ atom chirality, can significantly influence the charge migration process through the double helix. The above can be manifested by the slowdown of DNA lesion recognition and removal processes, which can increase the probability of mutagenesis and subsequent pathological processes. With regard to anticancer therapy (radio/chemo), the presence of (5′S)cdG in the structure of formed clustered DNA damage can lead to improvements in cancer treatment.

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Background: Women living in the Bolivian Andes are environmentally exposed to arsenic, yet there is scarce information about arsenic-related effects in this region. Several biomarkers for telomere length and oxidative stress (mitochondrial DNA copy number, mtDNAcn; 8-Oxo-2′-deoxyguanosine, 8-oxo-dG; and 4-hydroxy nonenal mercapturic acid, 4-HNE-MA) have been previously linked to arsenic, and some of which are prospective biomarkers for cancer risk. Objective and hypothesis: To evaluate associations between arsenic exposure and telomere length, mtDNAcn, 8-oxo-dG, and 4-HNE-MA in Bolivians. Arsenic exposure was hypothesized to be positively associated with all four toxicity biomarkers, particularly in individuals with a less efficient arsenic metabolism. Methods: The study encompassed 193 indigenous women. Arsenic exposure was assessed in urine as the sum of inorganic arsenic metabolite concentrations (U-As) measured by HPLC-HG-ICP-MS, and in whole blood as total arsenic (B-As) measured by ICP-MS. Efficiency of arsenic metabolism was evaluated by a polymorphism (rs3740393) in the main arsenic methylating gene AS3MT measured by TaqMan allelic discrimination, and by the relative fractions of urinary inorganic arsenic metabolites. Telomere length and mtDNAcn were determined in peripheral blood leukocytes by quantitative PCR, and urinary 8-oxo-dG and 4-HNE-MA by LC-MS/MS. Results: U-As and B-As were associated with longer telomeres and higher mtDNAcn, particularly in women with a less efficient arsenic metabolism. Urinary 8-oxo-dG and 4-HNE-MA were positively associated with U-As, but only 4-HNE-MA was associated with B-As. Arsenic metabolism efficiency did not have a clear effect on the concentrations of either of these biomarkers. Conclusion: Bolivian women showed indications of arsenic toxicity, measured by four different biomarkers. Telomere length, mtDNAcn, and 4-HNE-MA were positively associated with both U-As and B-As. The association of arsenic exposure with telomere length and mtDNAcn was only present in Bolivian women with a less efficient metabolism. These findings call for additional efforts to evaluate and reduce arsenic exposure in Bolivia.

Rodent alveolar/bronchiolar carcinomas (ABC) that arise either spontaneously or due to chemical exposure are similar to a subtype of lung adenocarcinomas in humans. B6C3F1/N mice and F344/NTac rats exposed to cobalt metal dust (CMD) by inhalation developed ABCs in a dose dependent manner. In CMD-exposed mice, the incidence of Kras mutations in ABCs was 67% with 80% of those being G to T transversions on codon 12 suggesting a role of oxidative stress in the pathogenesis. In vitro studies, such as DMPO (5,5-dimethyl-1-pyrroline N-oxide) immune-spin trapping assay, and dihydroethidium (DHE) fluorescence assay on A549 and BEAS-2B cells demonstrated increased oxidative stress due to cobalt exposure. In addition, significantly increased 8-oxo-dG adducts were demonstrated by immunohistochemistry in lungs from mice exposed to CMD for 90 days. Furthermore, transcriptomic analysis on ABCs arising spontaneously or due to chronic CMD-exposure demonstrated significant alterations in canonical pathways related to MAPK signaling (IL-8, ErbB, Integrin, and PAK pathway) and oxidative stress (PI3K/AKT and Melatonin pathway) in ABCs from CMD-exposed mice. Oxidative stress can stimulate PI3K/AKT and MAPK signaling pathways. Nox4 was significantly upregulated only in CMD-exposed ABCs and NOX4 activation of PI3K/AKT can lead to increased ROS levels in human cancer cells. The gene encoding Ereg was markedly up-regulated in CMD-exposed mice. Oncogenic KRAS mutations have been shown to induce EREG overexpression. Collectively, all these data suggest that oxidative stress plays a significant role in CMD-induced pulmonary carcinogenesis in rodents and these findings may also be relevant in the context of human lung cancers. [ABSTRACT FROM AUTHOR]

Mitochondrial (mt) DNA and nuclear (n) DNA have known structures and roles in cells; however, they are rarely compared under specific conditions such as oxidative or degenerative environments that can create damage to the DNA base moieties. Six purine lesions were ascertained in the mtDNA of wild type (wt) CSA (CS3BE–wtCSA) and wtCSB (CS1AN–wtCSB) cells and defective counterparts CS3BE and CS1AN in comparison with the corresponding total (t) DNA (t = n + mt). In particular, the four 5′,8–cyclopurine (cPu) and the two 8–oxo–purine (8–oxo–Pu) lesions were accurately quantified by LC–MS/MS analysis using isotopomeric internal standards after an enzymatic digestion procedure. The 8–oxo–Pu levels were found to be in the range of 25–50 lesions/107 nucleotides in both the mtDNA and tDNA. The four cPu were undetectable in the mtDNA both in defective cells and in the wt counterparts (CSA and CSB), contrary to their detection in tDNA, indicating a nonappearance of hydroxyl radical (HO•) reactivity within the mtDNA. In order to assess the HO• reactivity towards purine nucleobases in the two genetic materials, we performed γ–radiolysis experiments coupled with the 8–oxo–Pu and cPu quantifications on isolated mtDNA and tDNA from wtCSB cells. In the latter experiments, all six purine lesions were detected in both of the DNA, showing a higher resistance to HO• attack in the case of mtDNA compared with tDNA, likely due to their different DNA helical topology influencing the relative abundance of the lesions.

Urban wildlife often suffer poorer health than their counterparts living in more pristine environments due to exposure to anthropogenic stressors such as habitat degradation and environmental contamination. As a result, the health of urban versus nonurban snakes might be assessed by differences in their plasma biochemistries. We compared the plasma profiles of western tiger snakes (Notechis scutatus occidentalis) from a heavily urbanized wetland and a natural, nonurbanized wetland. Despite the urbanized snakes having lower body mass index, we found no significant difference between the plasma profiles of the two populations. We collected snakes from each population and kept them in captivity for 6 mo, providing them with stable conditions, uncontaminated (exempt from heavy metals and pesticides) food and water, and lowered parasite intensity in an attempt to promote better health through depuration. After captivity, snakes experienced a significant improvement in body mass index and significant changes in their plasma profiles. Snakes from the natural wetland initially had more variation of DNA damage; mean concentration of DNA damage in all snakes slightly decreased, but not significantly, after captivity. We present the plasma biochemistry profiles from western tiger snakes both before and after captivity and suggest a period of removal from natural stressors via captivity may offer a more reliable result of how plasma profiles of healthy animals might appear. [ABSTRACT FROM AUTHOR]

Background: DNA oxidative damage is a marker of increased oxidative stress activity. Elevated DNA oxidative damage has been associated with major depressive disorder in young adults, but there is no information about DNA oxidative damage in late-life depression. This study aims to evaluate whether older adults with late-life depression (LLD) has increased DNA oxidative damage compared to healthy older adults.Methods: We included 92 participants (57 with LLD [73.2 ± 7.7 years-old] and 35 non-depressed subjects (Controls) [70.5 ± 7.4 years-old]). We analyzed the plasma 8‑hydroxy-2'-deoxyguanosine (8-oxo-dG), a marker of DNA oxidation, using a commercially-available ELISA assay.Results: LLD participants had significantly higher 8-oxo-DG levels compared to controls (P<0.001). 8-oxo-dG levels were significantly correlated with depressive symptoms as assessed by the Hamilton Depression Rating Scale (rho=0.34, p<0.001). The plasma levels of 8-OHdG were not significantly correlated with other clinical, neurocognitive, and demographic variables.Limitations: Our current results are limited by the relatively small sample size, cross-sectional design, and the recruitment of participants in tertiary center for assessment and treatment of LLD.Conclusions: Older adults with LLD have increased DNA oxidative damage. Our findings provide additional evidence for elevated oxidative stress activity in LLD and the possible activation of age-related biological pathways and enhanced biological aging changes in LLD. [ABSTRACT FROM AUTHOR]

A preparative method for the synthesis of 8-oxo-2'-deoxyguanosine (8-oxo-dG) giving a high yield up to 80% and suitable for laboratory use is suggested. The urgency of the development of this method is associated with the need to obtain large quantities of 8-oxo-dG for the study of biological and pharmaceutical activity. Evidence of this need was obtained in the last decades, when the mechanisms of the interface of DNA repair with intracellular signaling through 8-oxo-dG were discovered and its anti-inflammatory and protective effects were revealed. The suggested method is based on the scheme used to prepare 8-oxo-dG-containing oligonucleotides, but has a number of important modifications. The use of N,N-dimethylformamide as a solvent makes it possible to increase the yield of the nucleophilic substitution reaction and avoid expensive and complicated further purification of silver acetate. Control of the reaction kinetics allows achieving the maximum yield and purity of the product. Alkaline hydrolysis, in contrast to ammonolysis, provides complete and rapid removal of acyl groups, and reversed-phase chromatography on silanized silica gel is an effective and inexpensive method of purification. Such a purification scheme minimizes contamination of the product with residual organic solvents, which is important for biological experiments. From the economic point of view, it is advantageous because of the absence of expensive solvents and the possibility of reusing the carrier. The method makes it possible to obtain pure 8-oxo-dG in preparative amounts and exceeds both its prototype and other existing techniques in the final output. Some intermediate compounds and significant methodological features of the reaction are described.

Graphical abstract Highlights • Tramadol activates NF-κB and up-regulates iNOS and cytokines. • Tramadol induces oxidative DNA damage in the cerebrum. • Tramadol up-regulates cerebral p53 and Bax, and down-regulates Bcl-2. • Tramadol increases cerebral serotonin and catecholamines. Abstract Tramadol is an opioid used as analgesic for treating moderate or sever pain. The long-term use of tramadol can induce several deleterious effects. We investigated the impact of chronic tramadol administration on the cerebrum of rats, focusing on oxidative damage, inflammation, apoptosis and changes in monoamine neurotransmitters. Rats received 30 or 60 mg/kg body weight tramadol dissolved in physiological saline daily for 8 weeks via oral gavage. Tramadol-induced rats showed significantly increased cerebral lipid peroxidation and nitric oxide, and deceased GSH content and activity and expression of the antioxidant enzymes. Tramadol administration for 8 weeks resulted in increased serum pro-inflammatory cytokines (TNF-α and IL-6) and expression of NF-κB, iNOS, TNF-α and IL-6 in the cerebrum of rats. Monoamine neurotransmitters, 8-oxo-7,8-dihydro-2′-deoxyguanosine, and gene and protein expression levels of p53 and Bax were significantly increased in the cerebrum of tramadol-induced rats. In contrast, chronic tramadol administration down-regulated Bcl-2 both gene and protein expression in the cerebrum of rats. In conclusion, our results indicate that the neurotoxic effect of chronic tramadol consumption is mediated via oxidative stress, inflammation and apoptosis. Tramadol provoked lipid peroxidation, up-regulated inflammation and apoptosis markers and altered neurotransmission in the cerebrum of rats. [ABSTRACT FROM AUTHOR]

Abstract Numerous lethal stresses in bacteria including antibiotics, thymineless death, and MalE-LacZ expression trigger an increase in the production of reactive oxygen species. This results in the oxidation of the nucleotide pool by radicals produced by Fenton chemistry. Following the incorporation of these oxidized nucleotides into the genome, the cell's unsuccessful attempt to repair these lesions through base excision repair (BER) contributes causally to the lethality of these stresses. We review the evidence for this phenomenon of incomplete BER-mediated cell death and discuss how better understanding this pathway could contribute to the development of new antibiotics. [ABSTRACT FROM AUTHOR]

Background Diabetes mellitus is a chronic disease caused by lack of insulin production in the pancreas or by insulin resistance, the disease being characterized by elevated blood glucose levels. Hyperglycemia in diabetes could lead to oxidative stress due to the rise in 8-oxo-2'-deoxyguanosine (8-oxo-dG) levels and the decrease in levels of total antioxidant status (TAS). The purpose of this study was to assess the effect Aloe vera extract on 8-oxo-dG level and total antioxidant status in diabetic rat testis. Methods This was an experimental laboratory study with 20 rat samples which were divided into 4 groups (1 control group and 3 treatment groups). Diabetes was induced in the rats by streptozotocin (STZ) at 65 mg/kgBW. The diabetic rats were then treated for 28 days with Aloe vera extract at 0 mg (P0), 200 mg rind (P1), 200 mg pulp (P2), respectively. The level of 8 -oxo-dG was measured by ELISA and total antioxidant status with 2,2' -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS). Data were analyzed with ANOVA and Least Significant Difference Advanced Test at P

The reaction of hydroxyl radical (HO•) with DNA produces many primary reactive species and many lesions as final products. In this study, we have examined the optical spectra of intermediate species derived from the reaction of HO• with a variety of single- and double-stranded oligodeoxynucleotides and ct-DNA in the range of 1 μs to 1 ms by pulse radiolysis using an Intensified Charged Coupled Device (ICCD) camera. Moreover, we applied our published analytical protocol based on an LC-MS/MS system with isotopomeric internal standards to enable accurate and precise measurements of purine lesion formation. In particular, the simultaneous measurement of the four purine 5′,8-cyclo-2′-deoxynucleosides (cPu) and two 8-oxo-7,8-dihydro-2′-deoxypurine (8-oxo-Pu) was obtained upon reaction of genetic material with HO• radicals generated either by γ-radiolysis or Fenton-type reactions. Our results contributed to the debate in the literature regarding absolute level of lesions, method of HO• radical generation, 5′R/5′S diastereomeric ratio in cPu, and relative abundance between cPu and 8-oxo-Pu.

Objective To assess the generation of reactive oxygen species (ROS) and the involvement of the main antioxidant pathways in low/intermediate-1-risk myelodysplastic syndromes (MDS) with iron overload (IOL). Methods We examined the levels of superoxide anion (O 2 − ), hydrogen peroxide (H 2 O 2 ), antioxidants (glutathione, GSH; superoxide dismutase, SOD; catalase, CAT; and glutathione peroxidase, GPx), mitochondrial membrane potential (ΔΨm), and by-products of oxidative damage (8-isoprostanes and 8-oxo-7,8-dihydro-2′-deoxyguanosine, 8-oxo-dG) in 42 MDS patients (28 without IOL at diagnosis, and 14 who developed IOL) and 20 healthy subjects. Results Patients with IOL showed higher O 2 − levels (39.4 MFI) than normal controls (22.7 MFI, p = 0.0356) and patients at diagnosis (19.4 MFI, p = 0.0049). Antioxidant systems, except SOD activity, exhibited significant changes in IOL patients with respect to controls (CAT: 7.1 vs 2.7 nmol/ml/min, p = 0.0023; GPx: 50.9 vs 76.4 nmol/ml/min, p = 0.0291; GSH: 50.2 vs 24.1 MFI, p = 0.0060). Furthermore, mitochondrial dysfunction was only detected in IOL cases compared to controls (ΔΨm: 3.6 vs 6.4 MFI, p = 0.0225). Finally, increased levels of 8-oxo-dG were detected in both groups of patients. Conclusion Oxidative stress is an important but non-static phenomenon in MDS disease, whose status is influenced by, among other factors, the presence of injurious iron. [ABSTRACT FROM AUTHOR]

Oxidative DNA damage has been associated with the pathophysiology of bipolar disorder (BD) as one of the common pathways between increased medical comorbidity and premature aging in BD. Previous evidence shows increased levels of oxidatively induced DNA damage markers, 8-hydroxy-2′-deoxyguanosine (8-OHdG) or its tautomer 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG), in patients with BD in comparison to healthy individuals. With the current research, we aim to analyze data on peripheral (blood or urine) 8-OHdG/8-oxo-dG levels across mood states of BD using a meta-analytical approach. A literature search was conducted using the databases PubMed, Scopus, and Web of Science to identify eligible studies (January 1989 to July 2022). Relevant studies were systematically reviewed; a random-effects meta-analysis and a meta-regression analysis were conducted. The current meta-analysis included 12 studies consisting of 808 BD patients (390 in euthymia, 156 in mania, 137 in depression, 16 in mixed episode, 109 not specified) and 563 healthy controls. BD patients that were currently depressed had significantly higher levels of 8-OHdG/8-oxo-dG than healthy controls, while euthymic or manic patients did not differ from healthy controls. A meta-regression analysis showed sex distribution (being female) and older age to be significantly related to increased 8-OHdG/8-oxo-dG levels. Our findings suggest that 8-OHdG/8-oxo-dG may be a state-related marker of depression in BD and may be affected by older age and female gender. • Patients with bipolar disorder in depression had higher levels of 8-OHdG compared to healthy controls. • 8-OHdG levels didn't differ in other mood states in bipolar disorder compared to healthy controls. • 8-OHdG can be a state-dependent marker of depression in bipolar disorder. [ABSTRACT FROM AUTHOR]

Background: The expression of 8-oxo-dG is defined as one form of damaged DNA occuring as the result of oxidation reaction due to X ray exposure. Panoramic radiography exposure has been widely known to be able to increase micronucleus which are signing the early stage and as biomarker in carsinogenesis mechanism. Purpose: The purpose of this research was to determine the correlation between micronucleus number and 8-oxo-dG expression as a result of panoramic radiography exposure. Methods: Twelve New Zealand male rabbits aging 6 months were divided into 4 groups. Group I were rabbits that represented 0 day, group II represented 3th day, group III represented 6th day, and group IV represented 9th day after the panoramic radiography exposure. Respectively samples were swabbed at mandibular anterior gingival mucosa before and after the panoramic radiography exposure. The swabbed samples were coloured by using Feulgen-Rossenbeck modified staining for calculating the amount of micronucleus formation. Expression of 8-oxodG was detected using immunohistochemical of rabbit’s gingival mucosa epithelium. Statistical analysis were carried out on pearson correlation. Results: There was a highest increasing of micronucleus on the 9th day after panoramic radiography exposure. Meanwhile, there was significant correlation (p=0,049) of the increasing amount of micronucleus and 8-oxo-dG expression in negatively correlation (r = -0,578). The increasing of micronucleus formation on the 9th day after panoramic radiography exposure was accordance with some previous studies. The expression score of 8-oxo-dG decreases as the day goes by. Conclusion: There was a correlation between the number of micronucleus and expression score of 8-oxo-dG.Latar belakang: Ekspresi 8-oxo-dG adalah suatu bentuk kerusakan DNA yang terjadi akibat reaksi oksidatif dari paparan sinar X. Paparan radiografi panoramik telah diketahui menyebabkan peningkatan jumlah mikronukleus yang merupakan biomarker tahap dini mekanisme karsinogenesis. Tujuan: Tujuan penelitian ini adalah untuk meneliti korelasi antara jumlah mikronukleus dan ekspresi 8-oxo-dG akibat paparan radiografi panoramik. Metode: Sebanyak 12 ekor kelinci New Zealand jantan usia 6 bulan dibagi menjadi 4 kelompok. Kelompok I merupakan kelinci untuk mewakili hari ke-0, kelompok II untuk mewakili hari ke-3, kelompok III untuk mewakili hari ke-6, dan kelompok IV untuk mewakili hari ke-9 setelah paparan radiografi panoramik. Terhadap seluruh kelinci dilakukan usapan pada mukosa gingiva anterior rahang bawah sebelum dan sesudah dilakukan paparan radiografi. Selanjutnya terhadap sampel usapan itu dilakukan pewarnaan menggunakan teknik pewarnaan modifikasi Feulgen-Rossenbeck untuk menghitung jumlah mikronukleus. Ekspresi 8-oxo-dG dinilai dari pemeriksaan imunohistokimia pada sel epitel mukosa gingiva kelinci. Analisis statistik menggunakan uji korelasi Pearson. Hasil: Peningkatan jumlah mikronukleus paling tinggi terjadi pada hari ke-9 setelah paparan radiografi panoramik. Sementara itu, terdapat korelasi yang signifikan (p=0,049) antara peningkatan jumlah mikronukleus dan ekspresi 8-oxo-dG dengan arah korelasi yang negatif (r=-0,578). Peningkatan jumlah mikronukleus yang terjadi pada hari ke-9 setelah paparan radiografi panoramik ini sesuai dengan penelitian sebelumnya. Dengan bertambahnya hari skor ekspresi 8-oxo-dG semakin menurun. Simpulan: Terdapat korelasi antara jumlah mikronukleus dan skor ekspresi 8-oxo-dG.

Objective: Oxidative DNA damage has been associated with the pathophysiology of bipolar disorder (BD) as one of the common pathways between increased medical comorbidity and premature aging in BD. Previous evidence shows increased levels of oxidatively induced DNA damage markers, 8-hydroxy-2'-deoxyguanosine (8-OHdG) or its tautomer 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), in patients with BD in comparison to healthy individuals. With the current research, we aim to analyze data on peripheral (blood or urine) 8-OHdG/8-oxo-dG levels across mood states of BD using a meta-analytical approach., Method: A literature search was conducted using the databases PubMed, Scopus, and Web of Science to identify eligible studies (January 1989 to July 2022). Relevant studies were systematically reviewed; a random-effects meta-analysis and a meta-regression analysis were conducted., Results: The current meta-analysis included 12 studies consisting of 808 BD patients (390 in euthymia, 156 in mania, 137 in depression, 16 in mixed episode, 109 not specified) and 563 healthy controls. BD patients that were currently depressed had significantly higher levels of 8-OHdG/8-oxo-dG than healthy controls, while euthymic or manic patients did not differ from healthy controls. A meta-regression analysis showed sex distribution (being female) and older age to be significantly related to increased 8-OHdG/8-oxo-dG levels., Conclusion: Our findings suggest that 8-OHdG/8-oxo-dG may be a state-related marker of depression in BD and may be affected by older age and female gender., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The deleterious effects of metal-catalyzed reactive oxygen species (ROS) in biological systems can be seen in a wide variety of pathological conditions including cancer, cardiovascular disease, ageing, and neurodegenerative disorder. On the other hand however, targeted ROS production in the vicinity of nucleic acids – as demonstrated by metal-activated bleomycin – has paved the way for ROS-active chemotherapeutic drug development. Herein we report mechanistic investigations into the oxidative nuclease activity and redox properties of copper(II) developmental therapeutics [Cu(DPQ)(phen)]2+ (Cu-DPQ-Phen), [Cu(DPPZ)(phen)]2+ (Cu-DPPZ-Phen), and [{Cu(phen)2}2(μ-terph)](terph) (Cu-Terph), with results being compared directly to Sigman’s reagent [Cu(phen)2]2+ throughout (phen = 1,10-phenanthroline; DPQ = dipyridoquinoxaline; DPPZ = dipyridophenazine). Oxidative DNA damage was identified at the minor groove through use of surface bound recognition elements of methyl green, netropsin, and [Co(NH3)6]Cl3 that functioned to control complex accessibility at selected regions. ROS-specific scavengers and stabilisers were employed to identify the cleavage process, the results of which infer hydrogen peroxide produced metal-hydroxo or free hydroxyl radicals (•OH) as the predominant species. The extent of DNA damage owing to these radicals was then quantified through 8-oxo-2'-deoxyguanosine (8-oxo-dG) lesion detection under ELISA protocol with the overall trend following Cu-DPQ-Phen > Cu-Terph > Cu-Phen > Cu-DPPZ. Finally, the effects of oxidative damage on DNA replication processes were investigated using the polymerase chain reaction (PCR) where amplification of 120 base pair DNA sequences of varying base content were inhibited – particularly along A-T rich chains – through oxidative damage of the template strands.

The formation of oxidative lesions arising from double stranded DNA damage is of major significance to chemical biology from the perspective of application to human health. The quantification of purine lesions arising from γ-radiation-induced hydroxyl radicals (HO•) has been the subject of numerous studies, with discrepancies on the measured 5',8-cyclo-2'-deoxyadenosine (cdA) and 5',8-cyclo-2'-deoxyguanosine (cdG) lesions reported by different groups. Recently we reported an ameliorative protocol for the analysis of DNA damage with quantitative determination of these lesions via isotope dilution liquid chromatography coupled with tandem mass spectrometry. Herein we applied this protocol for the quantification of these tandem-type purine lesions along with 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dG) and 7,8-dihydro-8-oxo-2'-deoxyadenosine (8-oxo-dA) in single and double stranded DNA, generated during DNA exposure to diffusible HO• radicals in the absence or presence of physiological levels of oxygen. The cdA and cdG lesions in absence of oxygen were found ~2 times higher in single than double stranded DNA, with 5'R being ~6.5 and ~1.5 times more predominant than 5'S in cdG and cdA, respectively. Interestingly, in the presence of 5% molecular oxygen the R/S ratios are retained with substantially decreased yields for cdA and cdG, whereas 8-oxo-dA and 8-oxo-dG remain nearly constant. The overall lesion formation follows the order: 8-oxo-dG >> 8-oxo-dA > 5'R-cdG > 5'R-cdA > 5'S-cdA > 5'S-cdG. By this method, there was a conclusive evaluation of radiation-induced DNA purine lesions.

A study is presented that investigate association of serum 8-hydro-2-deoxyguanosine (8-oxo-dG) in diabetes patients and using 8-oxo-dG as a biomarker for the oxidative stress in diabetes. It informs that the study was carried out in two group, patient with diabetes and control, and serum 8-oxo-dG was measured using a competitive enzyme-linked immunosorbent assay (ELISA) kit. The study found that Serum 8-oxo-dG can be used as a useful clinical biomarker in diagnosis and management of diabetes.

Due to the importance of the identification of chemotherapy outcome prognostic factors, we attempted to establish the potential of oxidative stress/DNA damage parameters such as prognostic markers. The aim of the study was to determine whether platinum derivative-based chemotherapy in cancer patients ( n = 66) is responsible for systemic oxidatively damaged DNA and whether damage biomarkers, such as 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) and the modified base 8-oxo-7,8-dihydroguanine (8-oxo-Gua), in urine and DNA may be used as a prognostic factor for the outcome of chemotherapy. All the aforementioned modifications were analyzed using techniques involving high-performance liquid chromatography/electrochemical detection (HPLC/EC) or HPLC/gas chromatography-mass spectrometry (GC-MS). Among all the analyzed parameters, the significantly decreased levels of 8-oxo-Gua in urine collected from a subgroup of patients 24 h after the first infusion of the drug, as compared with the baseline levels, correlated with a significantly longer overall survival (OS) (60 months after therapy) than in the subgroup without any decrease of this parameter after therapy (median OS = 24 months, p = 0.007). Moreover, a significantly longer OS was also observed in a group with increased urine levels of 8-oxo-dG after chemotherapy (38.6 vs. 20.5 months, p = 0.03). The results of our study suggest that patients with decreased 8-oxo-Gua levels and increased 8-oxo-dG levels in urine 24 h after the first dose should be considered as better responders to the administered chemotherapy, with a lower risk of death. The conclusion may permit the use of these parameters as markers for predicting the clinical outcome of platinum derivative-based chemotherapy. [ABSTRACT FROM AUTHOR]

Objective To investigate the potential compensatory effects of hOGG1 and hMTH1 in the repair of oxidative DNA damage. Methods The hOGG1 and hMTH1 gene knockdown human embryonic pulmonary fibroblast cell lines were established by lentivirus-mediated RNA interference. The messenger RNA (mRNA) levels of hOGG1 and hM1TH1 were analyzed by the real-time polymerase chain reaction, and 8-hydroxy-2′-deoxyguanosine (8-oxo-dG) formation was analyzed in a high-performance liquid chromatography-electrochemical detection system. Results The hOGG1 and hMTH1 knockdown cells were obtained through blasticidin selection. After transfection of hOGG1 and hMTH1 small interfering RNA, the expression levels of the mRNA of hOGG1 and hMTH1 genes were decreased by 97.2% and 96.2%, respectively. The cells then were exposed to 100 μmol/L of hydrogen peroxide (H 2 O 2 ) for 12 h to induce oxidative DNA damage. After H 2 O 2 exposure, hMTH1 mRNA levels were increased by 25% in hOGG1 gene knockdown cells, whereas hOGG1 mRNA levels were increased by 52% in hMTH1 gene knockdown cells. Following the treatment with H 2 O 2 , the 8-oxo-dG levels in the DNA of hOGG1 gene knockdown cells were 3.1-fold higher than those in untreated HFL cells, and 1.67-fold higher than those in H 2 O 2 -treated wild-type cells. The 8-oxo-dG levels in hMTH1 gene knockdown cells were 2.3-fold higher than those in untreated human embryonic pulmonary fibroblast cells, but did not differ significantly from those in H 2 O 2 -treated wild-type cells. Conclusion Our data suggested that hOGG1 could compensate for hMTH1 during oxidative DNA damage caused by H 2 O 2 , whereas hMTH1 could not compensate sufficiently for hOGG1 during the process. [ABSTRACT FROM AUTHOR]

Increasing evidence suggests that brain cytochrome P450 (CYP) can contribute to the in situ metabolism of xenobiotics. In the liver, some xenobiotics can be metabolized by CYPs into more reactive products that can damage hepatocytes and induce cell death. In addition, normal CYP activity may produce reactive oxygen species (ROS) that contribute to cell damage through oxidative mechanisms. CYP2E1 is a CYP isoform that can generate ROS leading to cytotoxicity in multiple tissue types. The aim of this study was to determine whether CYP2E1 induction may lead to significant brain cell impairment. Immunological analysis revealed that exposure of primary cerebellar granule neuronal cultures to the CYP inducer isoniazid, increased CYP2E1 expression. In the presence of buthionine sulfoximine, an agent that reduces glutathione levels, isoniazid treatment also resulted in reactive oxygen species (ROS) production, DNA oxidation and cell death. These effects were attenuated by simultaneous exposure to diallyl sulfide, a CYP2E1 inhibitor, or to a mimetic of superoxide dismutase/catalase, (Euka). These results suggest that in cases of reduced antioxidant levels, the induction of brain CYP2E1 could represent a risk of in situ neuronal damage. [ABSTRACT FROM AUTHOR]

Occupational exposure to nickel compounds has been associated with lung cancer. The correlation between high nickel levels and increased risk of lung cancer has been previously reported in a case-control study. This study assessed whether nickel exposure increased the occurrence of p53 mutations due to DNA repair inhibition by nickel. A total of 189 lung cancer patients were enrolled to determine nickel levels in tumor-adjacent normal lung tissues and p53 mutation status in lung tumors through atomic absorption spectrometry and direct sequencing, respectively. Nickel levels in p53 mutant patients were significantly higher than those in p53 wild-type patients. When patients were divided into high- and low-nickel subgroups by median nickel level, the high-nickel subgroup of patients had an odds ratio (OR) of 3.25 for p53 mutation risk relative to the low-nickel subgroup patients. The OR for p53 mutation risk of lifetime non-smokers, particularly females, in the high-nickel subgroup was greater than that in the low-nickel subgroup. To determine whether nickel affected DNA repair capacity, we conducted the host cell reactivation assay in A549 and H1975 lung cancer cells and showed that the DNA repair activity was reduced by nickel chloride in a dose-dependent manner. This was associated with elevated production of hydrogen peroxide-induced 8-oxo-deoxyguanosine. Therefore, increased risk of p53 mutation due to defective DNA repair caused by high nickel levels in lung tissues may be one mechanism by which nickel exposure contributes to lung cancer development, especially in lifetime female non-smokers. Environ. Mol. Mutagen. 55:624-632, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Objectives To analyze whether oxidative stress ( OS) changes are present in patients with bisphosphonate-related osteonecrosis of the jaw ( BRONJ) versus controls. Materials and Methods Oxidative stress was analyzed in serum and unstimulated saliva of three groups: Group 1 consisted of 24 patients who had been treated with intravenous bisphosphonates (iv BPs) and developed BRONJ, group 2 consisted of 20 patients who had received iv BPs and did not develop BRONJ, and group 3 comprised 17 control subjects. Reduced glutathione ( GSH), malondialdehyde ( MDA), oxidized glutathione ( GSSG), and 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxo-d G) levels, as well as the GSSG/ GSH ratio, were measured. Results Mean serum and saliva levels of MDA, GSSG, and 8-oxo-d G and the GSSG/ GSH ratio were significantly higher in patients with BRONJ than in controls. We found no significant difference in OS according to BRONJ stage, sex, or location in the jaws. Logistic regression analysis revealed that the GSSG/ GSH ratio was a significant factor predicting the development of BRONJ ( P = 0.01). Conclusions Oxidative stress was detected in patients with BRONJ, and the GSSG/ GSH ratio was the most significant OS variable found; it was a significant factor predicting the development of BRONJ. [ABSTRACT FROM AUTHOR]

Highlights: [•] hMTH1 protects cells from mutagenesis induced by UVA and UVB, but not UVC. [•] No protective role of hMTH1 in cell survival post UVB and UVC irradiation. [•] hMTH1 prevents induction of transition-type mutations at AT and GC post UVA irradiation. [•] 2-OH-dATP rather than 8-oxo-dGTP in the nucleotide pool likely contributes in UVA-induced mutations. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the study was to compare the radiation-induced oxidative stress response in blood samples from breast cancer patients that developed severe acute skin reactions during the radiotherapy, with the response in blood samples from patients with no side effects. Peripheral blood was collected from 12 breast cancer patients showing no early skin reactions after radiotherapy (RTOG grade 0) and from 14 breast cancer patients who developed acute severe skin reactions (RTOG grade 3–4). Whole blood was irradiated with 0, 5 and 2000mGy γ-radiation and serum was isolated. The biomarker for oxidative stress, 8-oxo-dG, was analyzed in the serum by a modified ELISA. While a significant radiation-induced increase of serum 8-oxo-dG levels was observed in serum of the RTOG 0 patients, no increase was seen in serum of the RTOG 3–4 patients. The radiation induced increase in serum 8-oxo-dG levels after 5mGy did not differ significantly from the increase observed for 2000mGy in the RTOG 3–4 cohort, thus no dose response relation was observed. A receiver operating characteristic (ROC) value of 0.97 was obtained from the radiation-induced increase in 8-oxo-dG indicating that the assay could be used to identify patients with severe acute adverse reactions to radiotherapy. The results show that samples of whole blood from patients, classified as highly radiosensitive (RTOG 3–4) based on their skin reactions to radiotherapy, differ significantly in their oxidative stress response to ionizing radiation compared to samples of whole blood from patients with no skin reactions (RTOG 0). Extracellular 8-oxo-dG is primarily a biomarker of nucleotide damage and the results indicate that the patients with severe acute skin reactions differ in their cellular response to ionizing radiation at the level of induction of oxidative stress or at the level of repair or both. [Copyright &y& Elsevier]

Abstract: This study investigated whether anti-CD40 Ab and 8-oxo-dG attenuate mast cell migration and EAE development. Anti-CD40 Ab and 8-oxo-dG reduced EAE scores, mast cell numbers, expression of adhesion molecules, OX40L and Act1, levels of TNF-α, LTs, expression of cytokines, and co-localization of Treg cells and mast cells, all of which are increased in EAE-brain tissues. Each treatment enhanced Treg cells, expression of OX40, and cytokines related to suppressive function of Treg cells in EAE brain tissues. Act-BMMCs with Treg cells reduced expression of OX40L and CCL2/CCR2, VCAM-1, PECAM-1, [Ca2+]i levels, release of mediators, various signaling molecules, Act1 related to IL-17a signals versus those in act-BMMCs without Treg cells. The data suggest that IL-10- and IL-35-producing Foxp3+-Treg cells, enhanced by anti-CD40 Ab or 8-oxo-dG, suppress migration of mast cells through down-regulating the expression of adhesion molecules, and suppress mast cell activation through cell-to-cell cross-talk via OX40/OX40L in EAE development. [Copyright &y& Elsevier]

Abstract: Background: Skin is uniquely vulnerable to damage caused by reactive oxygen species (ROS), which are most commonly produced in response to ultraviolet (UV) light. ROS generated at injury sites play an important role in modulating the inflammatory response. Besides inhibiting Rac, 7,8-dihydro-8-oxo-2′-deoxyguanosine (8-oxo-dG) has also shown notable antioxidant action. Objective: We tested whether 8-oxo-dG could protect skin from UVB-induced damage by scavenging ROS. Methods: HaCaT cells and hairless mice were irradiated with 15 and 180mJ/cm2 narrow-spectrum UVB, respectively. ROS generation was detected through incubation with DCFDA and confocal microscopy. Western blot analyses and immunohistochemistry were performed to verify the activities of ERK, JNK, p38, ATF-2, and c-Jun, and the expression of matrix metalloproteinases (MMPs), in UVB-irradiated HaCaT cells and murine skin. Hydrogen peroxide production and protein carbonyl concentrations were measured in UVB-damaged mouse skin. MMP-1 and MMP-9 expression in UVB-irradiated HaCaT cells was measured by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Results: In UVB-irradiated HaCaT cells, 8-oxo-dG inhibited ROS production, subsequent activation of mitogen-activated protein kinase (MAPK), ATF-2, and c-Jun, and MMP expression. It also prevented UV-induced skin reactions in hairless mice, inhibiting the increase in protein carbonyl content, activation of MAPKs, ATF-2, and c-Jun, the increases in MMP-9 and -13 expression, and epidermal hyperplasia. Conclusion: 8-oxo-dG can be considered an endogenous antioxidant and its potent antioxidant activity might be a beneficial property that could be exploited to protect skin from ROS-associated photodamage. [Copyright &y& Elsevier]

We characterized the oxidative stress (OS) status by the levels of reduced/oxidized glutathione (GSH/GSSG), malondialdehyde (MDA) and the mutagenic base 8-oxo-7'8-dihydro-2'-deoxyguanosine (8-oxo-dG) in human gastric carcinoma (HGC) samples and compared the results with normal tissue from the same patients. We also analyzed 8-oxo-dG in peripheral mononuclear cells (PMNC) and urine from healthy control subjects and in affected patients in the basal state and one, three, six, nine and twelve months after tumor resection. The levels of DNA repair enzyme mRNA expression (hOGG1, RAD51, MUYTH and MTH1) were determined in tumor specimens and compared with normal mucosa. Tumor specimens exhibited increased levels of MDA and 8-oxo-dG compared with normal gastric tissue. GSH levels were also increased, while GSSG levels remained stable. DNA repair enzyme mRNA expression was induced in the tumor tissues. Levels of 8-oxo-dG were significantly elevated in both urine and PMNC of gastric cancer patients compared with healthy controls. After gastrectomy, the levels of the damaged base in urine and PMNC decreased progressively to values close to those found in the healthy population. The high levels of 8-oxo-dG in urine may be related to the increased induction of DNA repair activity in tumor tissue, and the changes observed after tumor resection support its potential use as a tumor marker. [ABSTRACT FROM AUTHOR]

Abstract: Monoclonal B Lymphocytosis (MBL) is defined as asymptomatic monoclonal B-cell expansion characterised by a CLL-phenotype, but with less than 5×109/l circulating cells. Reactive oxygen species (ROS)-mediated cell damage plays a critical role in the initiation of carcinogenesis as well as in malignant transformation. The goal of this study was to perform an analysis of the oxidative stress statuses of patients affected by MBL and chronic lymphocytic leukaemia (CLL). We examined peripheral blood and urine specimens from 29 patients with MBL, 55 with CLL and 31 healthy subjects. There was a significant increase in the occurrence of the mutagenic base 8-oxo-2′-deoxiguanosine (8-oxo-dG) in the lymphocytes and urine of MBL and CLL patients compared with controls. Significant differences were also observed in the levels of the lipid peroxidation product malondialdehyde (MDA) and in the oxidised/reduced glutathione (GSSG/GSH) ratio, although an increase in 8-isoprostane was not detected. Interestingly, the antioxidant catalase activity of circulating lymphocytes decreased in the patient groups. In conclusion, early oxidative stress exists in patients with MBL and CLL, causing damage to DNA and lipid structures. The higher levels of 8-oxo-dG in lymphocytes than in urine may be related to a decrease in the capacity of DNA repair systems. There were no differences in the oxidative statuses of the MBL and CLL patients, suggesting that oxidative injuries appear during a pre-leukaemic state of the disease. [Copyright &y& Elsevier]

DNA is constantly exposed to reactive oxygen species (ROS), spontaneously arising during the normal oxygen metabolism. ROS may result in temporary as well as permanent modifications in various cellular components such as lipids, proteins and DNA, which may have deleterious consequences. Demonstrating that a dietary supplementation of antioxidants can reduce oxidative DNA damage may provide evidence for the value of such supplementation in prevention of cancer and age related diseases. Findings: The present study was conducted to address whether tomato juice protects against ROS induced by extensive physical exercise in untrained individuals. As a marker of oxidative stress, serum levels of 8-oxodG were monitored using a modified ELISA. An intervention was performed involving 15 untrained healthy subjects who performed a 20 min physical exercise at 80% of maximum pulse using an ergometer bicycle. Blood samples were taken before and one hour after the exercise. The procedure was repeated after 5 weeks with a daily intake of 150 ml tomato juice and followed by a 5 weeks wash-out period and another 5 weeks with a daily intake of tomato juice. The results indicated that a daily intake of tomato juice, equal to 15 mg lycopene per day, for 5 weeks significantly reduced the serum levels of 8-oxodG after an extensive physical exercise. Conclusion: These data strongly suggest that tomato juice has a potential antioxidant effect and may reduce the elevated level of ROS induced by oxidative stress. [ABSTRACT FROM AUTHOR]

Abstract: We have recently reported that Adap (adenosine-1,3-diazaphenoxazine) is an artificial nucleoside analogue for the specific recognition by multiple hydrogen bonding and that its fluorescence is selectively quenched with 8-oxo-2′-deoxyguanosine (8-oxo-dG) in DNA. We now report the development of a new OFF-to-ON type FRET probe, in which one strand contains Adap and another contains natural nucleotides for the formation of a less stable double strand. Each strand was labeled with Cy3 or BHQ2 at the 5′-end or 3′-end, respectively. It was expected in this system that fluorescence of the duplex probe is first quenched by FRET, but the target DNA strand containing 8-oxo-dG at the complementary site of Adap would enhance the displacement reaction of the less stable duplex probe that results in the fluorescence recovery. The results showed that the duplex probe containing the Adap-T base pair exhibited a complete discrimination between 8-oxo-dG and dG in DNA by fluorescence enhancement. [Copyright &y& Elsevier]

Abstract: UVA has been suggested to play an important role in UV-induced mutagenesis. The mechanisms by which UVA induces mutations are still a matter of debate. Our aim was to investigate the protective capacity of hMTH1, a nucleotide pool sanitization enzyme with 8-oxodGTPase activity. Human B lymphoblastoid cells were stably transfected with shRNA directed against hMTH1. Clonogenic survival, mutations, intracellular and extracellular levels of 8-oxodG (8-oxo-7, 8-dihydro-2′-deoxyguanosine) and dG in the nucleotide pool of UVA-irradiated transfected and non-transfected cells were investigated. Mutations were determined in the thymidine kinase locus. Intracellular 8-oxodG and dG were measured using a modified ELISA and HPLC, respectively, after extraction of the nucleotide pool and conversion of nucleotides to their corresponding nucleosides. 8-oxodG in the medium was measured using ELISA. UVA-induced mutations were significantly higher while the survival was slightly lower in transfected compared to non-transfected cells. The increased mutation rate in transfected cells at increased exposure correlated with enhanced levels of 8-oxodG in the nucleotide pool, and a somewhat reduced level of 8-oxodG in the medium. The results indicate that the nucleotide pool is a significant target for UVA-induced mutations and implicates that hMTH1 plays an important role in protecting cells from UVA-induced oxidative stress. [Copyright &y& Elsevier]

Palaemonetes australis is a euryhaline shrimp found in southwestern Australian estuaries. To determine if P. australis is a suitable bioindicator species for monitoring the health of estuarine biota, they were exposed to measured concentrations of the polycyclic aromatic hydrocarbon, benzo[ a]pyrene (B[ a]P) at 0.01, 0.1, or 1 ppm for 14 days under laboratory conditions. At the end of exposure the shrimp were sacrificed for biomarker [ethoxycoumarin O-deethylase (ECOD), 8-oxo-dG concentration, and sorbitol dehydrogenase (SDH) activity] analyses. Gender did not appear to influence biomarker responses of the shrimp in this study. ECOD activity was induced in the treatment groups in a linear fashion from three (0.01 ppm) times to 12 (1 ppm) times the negative controls. 8-oxo-dG concentration was reduced three times in treatment groups below the controls suggesting impaired DNA repair pathways. There was no increase in SDH, signifying hepatopancreatic cell damage had not occurred in any treatment group. The response of P. australis to B[ a]P exposure indicates that this crustacean is suitable bioindicator species for both laboratory studies and field monitoring. A combination of ECOD and SDH activities and 8-oxo-dG concentration represent a suitable suite of biomarkers for environmental monitoring of the sublethal effects of organic pollution to crustaceans from an estuarine environment. [ABSTRACT FROM AUTHOR]

In animal cells, recent studies have emphasized the role played by DNA topoisomerase I (topo I) both as a cofactor of DNA repair complexes and/or as a damage sensor. All these functions are still unexplored in plant cells, where information concerning the relationships between DNA damage, PCD induction, and topo I are also limited. The main goal of this study was to investigate the possible responses activated in topo I-depleted plant cells under oxidative stress conditions which induce DNA damage. The carrot (Daucus carota L.) AT1-β/22 cell line analysed in this study (characterized by an antisense-mediated reduction of top1β gene expression of approximately 46% in association with a low ascorbate content) was more sensitive to UV-C radiation than the control line, showing consistent cell death and high levels of 8-oxo-dG accumulation. The topo I-depleted cells were also highly susceptible to the cross-linking agent mitomycin C. The death response was associated with a lack of oxidative burst and there were no changes in ascorbate metabolism in response to UV-C treatment. Electron and fluorescence microscopy suggested the presence of three forms of cell death in the UV-C-treated AT1-β/22 population: necrosis, apoptotic-like PCD, and autophagy. Taken together, the data reported here support a reduced DNA repair capability in carrot topo I-deficient cells while the putative relationship between topo I-depletion and ascorbate impairment is also discussed. [ABSTRACT FROM PUBLISHER]

The impact of classic cardiovascular risk factors on oxidative stress status in a high-risk cardiovascular Mediterranean population of 527 subjects was estimated. Oxidative stress markers (malondialdehyde, 8-oxo-7′8′-dihydro-2′-deoxyguanosine, oxidized/reduced glutathione ratio) together with the activity of antioxidant enzyme triad (superoxide dismutase, catalase, glutathione peroxidase) were analysed in circulating mononuclear blood cells. Malondialdehyde, oxidized glutathione and the ratio of oxidized to reduced glutathione were significantly higher while catalase and glutathione peroxidase activities were significantly lower in high cardiovascular risk participants than in controls. Statistically significant differences were obtained after additional multivariate control for sex, age, obesity, diabetes, lipids and medications. Among the main cardiovascular risk factors, hypertension was the strongest determinant of oxidative stress in high risk subjects studied at a primary prevention stage. [ABSTRACT FROM AUTHOR]