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Fapy•dG (N6-(2-deoxy-α,β-D-erythro-pentofuranosyl)-2,6-diamino-4-hydroxy-5-formamidopyrimidine) and 8-OxodGuo (8-oxo-7,8-dihydro-2-deoxyguanosine) are major products of 2-deoxyguanosine oxidation. Fapy•dG is unusual in that it exists as a dynamic mixture of anomers. Much less is known about the effects of Fapy•dG than 8-OxodGuo on transcriptional bypass. The data presented here indicate that T7 RNA polymerase (T7 RNAP) bypass of Fapy•dG is more complex than that of 8-OxodGuo. Primer-dependent transcriptional bypass of Fapy•dG by T7 RNAP is hindered compared to 2-deoxyguanosine. T7 RNAP incorporates cytidine opposite Fapy•dG in a miniscaffold at least 13-fold more rapidly than A, G, or U. Fitting of reaction data indicates that Fapy•dG anomers are kinetically distinguishable. Extension of a nascent transcript past Fapy•dG is weakly dependent on the nucleotide opposite the lesion. The rate constants describing extension past fast- or slow-reacting base pairs vary less than twofold as a function of the nucleotide opposite the lesion. Promoter-dependent T7 RNAP bypass of Fapy•dG and 8-OxodGuo was carried out side by side. 8-OxodGuo bypass results in >55% A opposite it. When the shuttle vector contains a Fapy•dG:dA base pair, as high as 20% point mutations and 9% single-nucleotide deletions are produced upon Fapy•dG bypass. Error-prone bypass of a Fapy•dG:dC base pair accounts for ∼9% of the transcripts. Transcriptional bypass mutation frequencies of Fapy•dG and 8-OxodGuo measured in RNA products are comparable to or greater than replication errors, suggesting that these lesions could contribute to mutations significantly through transcription.

Objective: Mitochondrial DNA (mtDNA) depletion/deletions syndrome (MDDS) comprises a group of diseases caused by primary autosomal defects of mtDNA maintenance. Our objective was to study the etiology of MDDS in 4 patients who lack pathogenic variants in known genetic causes. Methods: Whole exome sequencing of the probands was performed to identify pathogenic variants. We validated the mitochondrial defect by analyzing mtDNA, mitochondrial dNTP pools, respiratory chain activities, and GUK1 activity. To confirm pathogenicity of GUK1 deficiency, we expressed 2 GUK1 isoforms in patient cells. Results: We identified biallelic GUK1 pathogenic variants in all 4 probands who presented with ptosis, ophthalmoparesis, and myopathic proximal limb weakness, as well as variable hepatopathy and altered T‐lymphocyte profiles. Muscle biopsies from all probands showed mtDNA depletion, deletions, or both, as well as reduced activities of mitochondrial respiratory chain enzymes. GUK1 encodes guanylate kinase, originally identified as a cytosolic enzyme. Long and short isoforms of GUK1 exist. We observed that the long isoform is intramitochondrial and the short is cytosolic. In probands' fibroblasts, we noted decreased GUK1 activity causing unbalanced mitochondrial dNTP pools and mtDNA depletion in both replicating and quiescent fibroblasts indicating that GUK1 deficiency impairs de novo and salvage nucleotide pathways. Proband fibroblasts treated with deoxyguanosine and/or forodesine, a purine phosphatase inhibitor, ameliorated mtDNA depletion, indicating potential pharmacological therapies. Interpretation: Primary GUK1 deficiency is a new and potentially treatable cause of MDDS. The cytosolic isoform of GUK1 may contribute to the T‐lymphocyte abnormality, which has not been observed in other MDDS disorders. ANN NEUROL 2024;96:1209–1224 [ABSTRACT FROM AUTHOR]

Introduction: Deoxyguanosine Kinase (DGUOK) deficiency is a very rare disorder characterized by liver dysfunction, neurological manifestations, and metabolic disorders secondary to severely reduced mitochondrial DNA content. These patients develop early-onset liver failure, and their liver transplantation (LT) indication remains debatable due to the possibility of neurological involvement. Case Report: We present the case of a 6-month-old female diagnosed with DGUOK deficiency who developed liver failure. At 9 months, she underwent a living-related LT with an initial favorable evolution under immunosuppression therapy with tacrolimus. Four months after LT, she presented two prolonged bacterial and Rotavirus enteritis episodes. She developed classical post-transplant complications (severe renal tubular acidosis type IV, secondary to the high tacrolimus level, and post-transplant lymphoproliferative disease) during these episodes. Her condition deteriorated progressively, with reversible hypotonia and significant weight loss. However, the neurological evaluation did not reveal any signs suggestive of the progression of the underlying disease. A few months later, her clinical features and laboratory parameters improved considerably. Conclusions: This case highlights the unpredictable evolution of children with LT for liver failure due to DGUOK deficiency. [ABSTRACT FROM AUTHOR]

Understanding the occurrence, repair, and biological consequences of DNA damage is important in environmental toxicology and risk assessment. The most common way to assess DNA damage elicited by exogenous sources in a laboratory setting is to expose cells or experimental animals with chemicals that modify DNA. Owing to the lack of reaction specificities of DNA damaging agents, the approach frequently does not allow for induction of a specific DNA lesion. Herein, we employed metabolic labeling to selectively incorporate N2-methyl-dG (N2-MedG) and N2-n-butyl-dG (N2-nBudG) into genomic DNA of cultured mammalian cells, and investigated how the levels of the two lesions in cellular DNA are modulated by different DNA repair factors. Our results revealed that nucleotide excision repair (NER) exert moderate effects on the removal of N2-MedG and N2-nBudG from genomic DNA. We also observed that DNA polymerases κ and η contribute to the incorporation of N2-MedG into genomic DNA and modulate its repair in human cells. In addition, loss of ALKBH3 resulted in higher frequencies of N2-MedG and N2-nBuG incorporation into genomic DNA, suggesting a role of oxidative dealkylation in the reversal of these lesions. Together, our study provided new insights into the repair of minor-groove N2-alkyl-dG lesions in mammalian cells.

Background: Deoxyguanosine kinase (DGUOK) deficiency is a rare mitochondrial disorder characterized by early onset liver failure and varying degrees of neurologic dysfunction. Patients typically present during infancy with progressive hepatic dysfunction leading to liver failure, which can precede neurologic deterioration. Outcomes posttransplantation are historically worse than average and the role of liver transplantation remains controversial. These factors, in combination with the increasing number of patients being diagnosed via molecular genetic testing, may impede waitlist access. Methods: We report our single‐center experience with three patients with DGUOK deficiency, all of whom were considered for transplant. We review the current literature regarding management and discuss the role of liver transplantation in DGUOK deficiency‐associated liver failure. Results: Two patients presented with hypoglycemia, conjugated hyperbilirubinemia, and lactic acidosis within the first week of life, were diagnosed with DGUOK deficiency prior to 2 months of age and had severe neurologic involvement. The third patient presented in later infancy was diagnosed with DGUOK deficiency at 18 months of age and had minimal neurologic involvement. All three patients were considered for transplant, though only two patients were listed. All three died from complications of end‐stage liver failure prior to liver transplantation between the ages of 5–20 months. Conclusion: Selection for liver transplantation in DGUOK deficiency is complex, requiring a multidisciplinary team approach. Recent data suggest that liver transplantation can be successful in select patients with absent or mild neurologic manifestations. National databases reporting long‐term outcomes posttransplantation are needed. [ABSTRACT FROM AUTHOR]

Objective: To explore the value of serum s PLA2-X, 8-hydroxy-2’-deoxyguanosine, and hs CRP levels in diagnosing acute exacerbation of chronic obstructive pulmonary disease. Methods: A total of 128 COPD patients who underwent treatment in our hospital from March 2021 to November 2023 were randomly selected. The patients were divided into a stable group and an AECOPD group based on whether they experienced acute exacerbation. Among them, 29 were in the stable group and 99 were in the AECOPD group. Compare the differences in peripheral blood s PLA2-X, 8-OHd G, and hs CRP levels between the two groups of study subjects; The COX proportional risk factor regression model is used to analyze the influencing factors of AECOPD, and the ROC curve is used to analyze the value of related indicators for individual and combined detection and diagnosis of AECOPD. Results: The FEV1 index in the AECOPD group was significantly lower than that in the stable group, with a statistically significant difference （P＜0. 05）. Compared with the stable group, the peripheral blood s PLA2-X, 8-OHd G, and hs CRP levels in the AECOPD group were significantly increased, with statistical significance （P＜0. 01）. The levels of s PLA2-X, 8-Ohd G, and hs CRP in peripheral blood were positively correlated with GOLD grading （P＜0. 05）, while the levels of s PLA2-X, 8-Ohd G, and hs CRP in peripheral blood were negatively correlated with FEV1/FVC （%）and FEV1%pred（P＜0. 05）. Using the COX proportional risk factor regression model analysis, peripheral blood s PLA2-X, 8-Ohd G, and hs CRP were all independent risk factors affecting AECOPD. The area under the curve （AUC） of peripheral blood s PLA2-X, 8-Ohd G, and hs CRP in diagnosing AECOPD using ROC curve analysis were 0. 689, 0. 708, 0. 642, and 0. 875, respectively. The combined predictive value of each indicator was significantly higher than that of individual detection. Conclusion: The peripheral blood s PLA2-X, 8-Ohd G, and hs CRP levels in AECOPD patients are highly expressed. The levels of s PLA2-X, 8-Ohd G, and hs CRP in peripheral blood are correlated with the severity of lung function and lung function indicators, and can be used as potential predictive indicators for diagnosing acute exacerbation in COPD patients. The combination of the three has higher diagnostic value. [ABSTRACT FROM AUTHOR]

To cope with unrepaired DNA lesions, cells are equipped with DNA damage tolerance mechanisms, including translesion synthesis (TLS). While TLS polymerases are well documented in facilitating replication across damaged DNA templates, it remains unknown whether TLS polymerases participate in transcriptional bypass of DNA lesions in cells. Herein, we employed the competitive transcription and adduct bypass assay to examine the efficiencies and fidelities of transcription across N2-alkyl-2-deoxyguanosine (N2-alkyl-dG, alkyl = methyl, ethyl, n-propyl, or n-butyl) lesions in HEK293T cells. We found that N2-alkyl-dG lesions strongly blocked transcription and elicited CC → AA tandem mutations in nascent transcripts, where adenosines were misincorporated opposite the lesions and their adjacent 5 nucleoside. Additionally, genetic ablation of Pol η, but not Pol κ, Pol ι, or Pol ζ, conferred marked diminutions in the transcriptional bypass efficiencies of the N2-alkyl-dG lesions, which is exacerbated by codepletion of Rev1 in Pol η-deficient background. We also observed that the repair of N2-nBu-dG was not pronouncedly affected by genetic depletion of Pol η or Rev1. Hence, our results provided insights into transcriptional perturbations induced by N2-alkyl-dG lesions and expanded the biological functions of TLS DNA polymerases.

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in environments, and some of them are causative agents of human cancer. Previous studies concluded that benzo[a]pyrene-7,8-dione (BPQ), which is one kind of carcinogenic PAH metabolites, forms covalently bonded adducts with DNA, and the major adduct formed is a deoxyguanosine adduct. In this work, we investigate the interactions between BPQ and DNA molecules via first-principles calculations. We identify six possible DNA adducts with BPQ. In addition to the four adducts forming covalent bonds, there are two adducts bound purely by van der Waals (vdW) interactions. Remarkably, the two vdW-bound adducts have comparable, if not larger, binding energies as the covalent adducts. The results may help us gain more understanding of the interactions between PAH metabolites and DNA. [ABSTRACT FROM AUTHOR]

Alkylation represents a main form of DNA damage. The N2 position of guanine is frequently alkylated in DNA. The SOS-induced polymerases have been shown to be capable of bypassing various DNA damage products in Escherichia coli. Herein, we explored the influences of four N2-alkyl-dG lesions (alkyl = ethyl, n-butyl, isobutyl, or sec-butyl) on DNA replication in AB1157 E. coli cells and the corresponding strains with polymerases (Pol) II, IV, and V being individually or simultaneously knocked out. We found that N2-Et-dG is slightly less blocking to DNA replication than the N2-Bu-dG lesions, which display very similar replication bypass efficiencies. Additionally, Pol II and, to a lesser degree, Pol IV and Pol V are required for the efficient bypass of the N2-alkyl-dG adducts, and none of these lesions was mutagenic. Together, our results support that the efficient replication across small N2-alkyl-dG DNA adducts in E. coli depends mainly on Pol II.

Background: Deoxyguanosine kinase deficiency is mainly manifested by hepatic and neurological damage, hence it belongs to the hepatocerebral form of mitochondrial deoxyribonucleic acid depletion syndrome. The association between deoxyguanosine kinase deficiency and recurrent spontaneous pneumothorax has not currently been reported. Case presentation: A 12-year-old Russian boy with deoxyguanosine kinase deficiency, a recipient of a liver transplant with amyotrophy secondary to his mitochondriopathy, presented with recurrent spontaneous bilateral pneumothorax refractory to drainage and surgery. Conclusion: To our knowledge, this is the first documented case of deoxyguanosine kinase deficiency associated with recurrent spontaneous pneumothorax, which could be considered a late complication of deoxyguanosine kinase deficiency. At this point, this is only an association and further studies and research need to be performed to help confirm the pathogenesis of this association. [ABSTRACT FROM AUTHOR]

We aimed to see the effect of lipids on 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of DNA damage, and Interleukin-6 (IL-6), an inflammatory cytokine, in Diabetes Mellitus (DM) patients. Serum IL-6, and 8-OHdG levels were determined using kits based on the ELISA principle. The groups were different in terms of total cholesterol, LDL cholesterol and triglyceride. Group 2 (dyslipidemia positive DM positive) was significantly higher than the other groups. There was no statistical difference between group 1 (dyslipidemia negative DM positive) and the control group (p<0.001). 8-OHdG levels differ between groups. The level of 8-OHdG was significantly higher in group 2 compared to the other groups (p<0.001). IL-6 was different between groups. Group 2, IL-6 level was found to be significantly higher than the other groups (p<0.001). A positive correlation was found between serum 8-OHdG level and total cholesterol (r=0.417 p<0.001), LDL cholesterol (r=0.491 p<0.001) and triglyceride (r=0.441 p<0.001). A positive correlation was found between IL-6 and total cholesterol (r=0.522 p<0.001), LDL cholesterol (r=0.646 p<0.001) and triglyceride (r=0.495 p<0.001). IL-6 and 8-OHdG levels are high in dyslipidemic DM patients with a high lipid profile. IL-6 and 8-OHdG levels are elevated in dyslipidemic DM patients with a high lipid profile. IL-6 and 8-OHdG can be used as biomarkers to evaluate dyslipidemic complications seen in DM patients in the early diagnosis. [ABSTRACT FROM AUTHOR]

Recently, 1,5-anhydro-D-glucitol (1,5-AG) has been manufactured using microbe-derived enzymes and we previously reported that it inhibits intestinal sucrase and maltase activity. However, its function in supplements for diabetes prevention has not been clarified. We investigated the effect feeding of 1,5-AG has of delaying the onset of diabetes through its antioxidant properties. KKAy mice were raised with an AIN93G (control), 3 % or 6 % 1,5-AG, or 6 % erythritol (ERT, positive control) diet for 7 weeks. Urinary glucose excretion in the 6 % 1,5-AG group at 4 and 6 weeks and in the 6 % ERT group at 4, 6, and 7 weeks was significantly lower than in the control group (p < 0.05). After 7 weeks, urine 8-hydroxy-2’- deoxyguanosine, fasting plasma glucose, insulin, total cholesterol, and triacylglycerol in the 6 % 1,5-AG group were lower than in the control group (p < 0.05). Feeding of 6 % 1,5-AG appears to prevent the onset of diabetes-related symptoms through its systemic antioxidant effect. [ABSTRACT FROM AUTHOR]

Acrylamide, a common food contaminant, is metabolically activated to glycidamide, which reacts with DNA at the N7 position of dG, forming N7-(2-carbamoyl-2-hydroxyethyl)-dG (GA7dG). Owing to its chemical lability, the mutagenic potency of GA7dG has not yet been clarified. We found that GA7dG undergoes ring-opening hydrolysis to form N6-(2-deoxy-d-erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5-[N-(2-carbamoyl-2-hydroxyethyl)formamido]pyrimidine (GA-FAPy-dG), even at neutral pH. Therefore, we aimed to examine the effects of GA-FAPy-dG on the efficiency and fidelity of DNA replication using an oligonucleotide carrying GA-FAPy–9-(2-deoxy-2-fluoro-β-d-arabinofuranosyl)guanine (dfG), a 2′-fluorine substituted analog of GA-FAPy-dG. GA-FAPy-dfG inhibited primer extension by both human replicative DNA polymerase ε and the translesion DNA synthesis polymerases (Polη, Polι, Polκ, and Polζ) and reduced the replication efficiency by less than half in human cells, with single base substitution at the site of GA-FAPy-dfG. Unlike other formamidopyrimidine derivatives, the most abundant mutation was G:C > A:T transition, which was decreased in Polκ- or REV1-KO cells. Molecular modeling suggested that a 2-carbamoyl-2-hydroxyethyl group at the N5 position of GA-FAPy-dfG can form an additional H-bond with thymidine, thereby contributing to the mutation. Collectively, our results provide further insight into the mechanisms underlying the mutagenic effects of acrylamide. [ABSTRACT FROM AUTHOR]

Exogenous and endogenous chemicals can react with DNA to produce DNA lesions that may block DNA replication. Not much is known about the roles of polymerase (Pol) ν and Pol θ in translesion synthesis (TLS) in cells. Here we examined the functions of these two polymerases in bypassing major-groove O6-alkyl-2-deoxyguanosine (O6-alkyl-dG) and minor-groove N2-alkyl-dG lesions in human cells, where the alkyl groups are ethyl, n-butyl (nBu), and, for O6-alkyl-dG, pyridyloxobutyl. We found that Pol ν and Pol θ promote TLS across major-groove O6-alkyl-dG lesions. O6-alkyl-dG lesions mainly induced G→A mutations that were modulated by the two TLS polymerases and the structures of the alkyl groups. Simultaneous ablation of Pol ν and Pol θ resulted in diminished mutation frequencies for all three O6-alkyl-dG lesions. Depletion of Pol ν alone reduced mutations only for O6-nBu-dG, and sole loss of Pol θ attenuated the mutation rates for O6-nBu-dG and O6-pyridyloxobutyl-dG. Replication across the two N2-alkyl-dG lesions was error-free, and Pol ν and Pol θ were dispensable for their replicative bypass. Together, our results provide critical knowledge about the involvement of Pol ν and Pol θ in bypassing alkylated guanine lesions in human cells.

Mass spectrometry and tandem MS (MS/MS) have been widely employed for the identification and quantification of damaged nucleosides in DNA, including those induced by alkylating agents. Upon collisional activation, protonated ions of alkylated nucleosides frequently undergo facile neutral loss of a 2-deoxyribose in MS/MS, and further cleavage of the resulting protonated nucleobases in MS3 can sometimes be employed for differentiating regioisomeric alkylated DNA lesions. Herein, we investigated systematically the collision-induced dissociation (CID) of the protonated ions of O4-alkylthymidine (O4-alkyldT), O2-alkyldT, O6-alkyl-2-deoxyguanosine (O6-alkyldG), and N2-alkyldG through MS3 analysis. The MS3 of O2- and O4-MedT exhibit different fragmentation patterns from each other and from other O2- and O4-alkyldT adducts carrying larger alkyl groups. Meanwhile, elimination of alkene via a six-membered ring transition state is the dominant fragmentation pathway for O2-alkyldT, O4-alkyldT, and O6-alkyldG adducts carrying larger alkyl groups, whereas O6-MedG mainly undergoes elimination of ammonia. The breakdown of N2-alkyldG is substantially influenced by the structure of the alkyl group, where the relative ease in eliminating ammonia and alkene is modulated by the chain length and branching of the alkyl groups. We also rationalize our observations with density functional theory (DFT) calculations.

Abstract Background Frequent heavy air pollution occurred during the winter heating season of northern China. Particulate air pollution is a serious concern in Urumqi during heating season. Exposure to air pollution is known to increase adverse health outcomes, particularly oxidative damage. This study aimed to evaluate the impact of air pollution on oxidative damage around pregnant women and newborns in Urumqi. Methods This prospective observational study enrolled pregnant women in the Fifth Affiliated Hospital of Xinjiang Medical University between January 2019 and October 2019. Pregnant women and newborns were allocated into a heating season group (January - end of April 2019, October 2019) or non-heating season group (June 2019 - end of September) according to the specific delivery time. Venous blood, urine from the women and cord blood from their newborns were collected to measure the levels of PAHs and 8-deoxyguanosine (8-OHdG), a measure of oxidative stress. Results A total of 200 pregnant women and newborns were enrolled, with 100 pregnant women and newborns in the heating season group. Compared to the non-heating season group, the total contents of 8-OHdG in maternal urine, PAHs and 8-OHdG in maternal plasma and neonatal cord blood were higher in the heating season group (all P

Endogenous metabolites and exogenous chemicals can induce covalent modifications on DNA, producing DNA lesions. The N2 of guanine was shown to be a common alkylation site in DNA; however, not much is known about the influence of the size of the alkyl group in N2-alkyldG lesions on cellular DNA replication or how translesion synthesis (TLS) polymerases modulate DNA replication past these lesions in human cells. To answer these questions, we employ a robust shuttle vector method to investigate the impact of four N2-alkyldG lesions (i.e., with the alkyl group being a methyl, ethyl, n-propyl, or n-butyl group) on DNA replication in human cells. We find that replication through the N2-alkyldG lesions was highly efficient and accurate in HEK293T cells or isogenic CRISPR-engineered cells with deficiency in polymerase (Pol) ζ or Pol η. Genetic ablation of Pol ι, Pol κ, or Rev1, however, results in decreased bypass efficiencies and elicits substantial frequencies of G → A transition and G → T transversion mutations for these lesions. Moreover, further depletion of Pol ζ in Pol κ- or Pol ι-deficient cells gives rise to elevated rates of G → A and G → T mutations and substantially decreased bypass efficiencies. Cumulatively, we demonstrate that the error-free replication past the N2-alkyldG lesions is facilitated by a specific subset of TLS polymerases, and we find that longer alkyl chains in these lesions induce diminished bypass efficiency and fidelity in DNA replication.

Cladribine is a deoxyadenosine analog prodrug originally developed to treat hairy-cell leukemia and other lymphoproliferative diseases. However, it is now primarily used in the treatment of relapsing types of multiple sclerosis (MS). Understanding how medications interact with dsDNA is crucial for developing more effective and efficient medications. This study aims to examine the binding behavior of cladribine with dsDNA via various analytical methods, such as heat denaturation, UV spectroscopy, fluorescence spectroscopy, electrochemistry, and viscosity tests. The binding constant (K b) of cladribine with dsDNA has been estimated to be 2.41 × 104 ± 0.20 at 298 K using the Benesi-Hildebrand plot. Molecular docking simulations were employed to explore the dsDNA-cladribine interactions quantitatively at the molecular level. Molecular Dynamic simulations were performed to follow the stability of drug-bound DNA for 50 ns. The simulations revealed that cladribine binds to dsDNA via the minor groove region of DNA by forming hydrogen bonds mainly with Guanine's DNA bases. The post-MD analyses enabled us to follow the stability of DNA and cladribine complex. Additionally, two methods based on the electrochemical approach were developed in this study for low-level cladribine assessment using differential pulse voltammetry (DPV). The first method relies on cladribine oxidation in pH 2 phosphate buffer, while the second method uses deoxyguanosine oxidation signals resulting from cladribine and dsDNA binding in pH 4.80 acetate buffer. The analytical efficacy of the two methods was verified using cladribine concentrations ranging from 2 to 25 μM, with a limit of detection (LOD) of 0.30 and 0.92 μM, respectively. Furthermore, the study conducted percent recovery tests by employing pharmaceutical injection using both established methodologies. [ABSTRACT FROM AUTHOR]

Through the utilization of fluorescence spectroscopy, electrochemical, and molecular docking methods, this research investigates the interaction between the antihistamine drug desloratadine and calf thymus double-stranded DNA (ct-dsDNA). Deoxyguanosine (dGuo) and deoxyadenosine (dAdo) oxidation signals were diminished by incubation with varying concentrations of desloratadine, as determined by differential pulse voltammetry (DPV). This change was ascribed to desloratadine's binding mechanism to ct-dsDNA. The binding constant (K b) between desloratadine and ct-dsDNA was determined to be 2.2 × 105 M−1 throughout electrochemical experiments. In order to further develop our comprehension of the interaction mechanism between desloratadine and ct-dsDNA, a series of spectroscopic experiments and molecular docking simulations were conducted. The K b value was found to be 8.85 × 104 M−1 at a temperature of 25 °C by the use of fluorescence spectroscopic techniques. In summary, the utilization of electrochemical and spectroscopic techniques, alongside molecular docking investigations, has led to the prediction that desloratadine has the capability to interact with ct-dsDNA by groove binding. [Display omitted] • The DNA and Desloratadine interaction was investigated for the first time by voltammetric, spectroscopic and molecular modeling techniques. • The binding event's thermodynamic profile and binding constant are determined. • Molecular docking substantiates the groove-binding mode of interaction. • The interaction mechanism proposed by computational approaches provides a good depiction of the electrochemical interaction. [ABSTRACT FROM AUTHOR]

A wide spectrum of DNA lesions can be generated from byproducts of endogenous metabolism and/or from environmental exposure. A DNA adductomic approach for the robust quantification of DNA adducts in cellular and tissue DNA may facilitate the use of DNA adducts for biomonitoring studies and enable comprehensive assessment about DNA repair. Normalized retention time (iRT) has been widely used in scheduled selected-reaction monitoring (SRM) methods for highly sensitive and high-throughput analyses of protein samples in complicated matrices. By using a similar method, we established the iRT scores for 36 modified nucleosides from the retention times of the four canonical 2-deoxynucleosides on a nanoflow liquid chromatography-nanospray ionization-tandem mass spectrometry (nLC-NSI-MS/MS) system. The iRT scores facilitated reliable prediction of retention time and were employed for establishing a scheduled SRM method for quantitative assessment of a subset of the DNA adductome. The quantification results of the scheduled SRM method were more accurate and precise than those from an unscheduled method.

Standard and targeted cancer therapies for late-stage cancer patients almost universally fail due to tumor heterogeneity/plasticity and intrinsic or acquired drug resistance. We used the telomerase substrate nucleoside precursor, 6-thio-2'-deoxyguanosine (6-thio-dG), to target telomerase-expressing non-small cell lung cancer cells resistant to EGFR-inhibitors and commonly used chemotherapy combinations. Colony formation assays, human xenografts as well as syngeneic and genetically engineered immune competent mouse models of lung cancer were used to test the effect of 6-thio-dG on targeted therapy- and chemotherapy-resistant lung cancer human cells and mouse models. We observed that erlotinib-, paclitaxel/carboplatin-, and gemcitabine/cisplatin-resistant cells were highly sensitive to 6-thio-dG in cell culture and in mouse models. 6-thio-dG, with a known mechanism of action, is a potential novel therapeutic approach to prolong disease control of therapy-resistant lung cancer patients with minimal toxicities.

Understanding the dose-response for formaldehyde-induced nasal cancer in rats is complicated by (1) the uneven distribution of inhaled formaldehyde across the interior surface of the nasal cavity and, (2) the presence of endogenous formaldehyde (endoF) in the nasal mucosa. In this work, we used computational fluid dynamics (CFD) modeling to predict flux of inhaled (exogenous) formaldehyde (exogF) from air into tissue at the specific locations where DNA adducts were measured. Experimental work has identified DNA-protein crosslink (DPX) adducts due to exogF and deoxyguanosine (DG) adducts due to both exogF and endoF. These adducts can be considered biomarkers of exposure for effects of endoF and exogF on DNA that may be part of the mechanism of tumor formation. We describe a computational model linking CFD-predicted flux of formaldehyde from air into tissue, and the intracellular production of endoF, with the formation of DPX and DG adducts. We assumed that, like exogF, endoF can produce DPX. The model accurately reproduces exogDPX, exogDG, and endoDG data after inhalation from 0.7 to 15 ppm. The dose-dependent concentrations of exogDPX and exogDG are predicted to exceed the concentrations of their endogenous counterparts at about 2 and 6 ppm exogF, respectively. At all concentrations examined, the concentrations of endoDPX and exogDPX were predicted to be at least 10-fold higher than that of their DG counterparts. The modeled dose-dependent concentrations of these adducts are suitable to be used together with data on the dose-dependence of cell proliferation to conduct quantitative modeling of formaldehyde-induced rat nasal carcinogenicity. [ABSTRACT FROM AUTHOR]

[Display omitted] Co-crystallization of active pharmaceutical ingredients (API) with co-formers can induce synergistic effects on cytotoxicity; however, the underlying mechanism is unclear. Here, cell metabolomics was used to gain insight into the mechanisms of synergistic effect from API and co-former in co-crystal. The 5-Fluorouracil-phenylalanine co-crystal system was selected as the model owing to the apparent difference of cytotoxicity occurring between co-crystal and physical mixture of two components (PM). The cytotoxicity of 5-FU, PM and co-crystal on B16 cells were evaluated by MTT assay. Based on the IC 50 values from MTT assays, the cytotoxicity mechanism of 5-FU, PM and co-crystal was evaluated using a comprehensive non-targeted metabolomics strategy based on multivariate data analysis and statistics using UHPLC-Q-TOF-MS/MS platform with IDA data acquisition. Co-crystal showed higher cytotoxicity than PM against B16 cells. In the cell metabolomics study, a total of 12 differential metabolites were found. Pathway analysis indicated that differences in purine and glycerophospholipid metabolism occurred between PM and co-crystal. The downregulated deoxyguanosine diphosphate and adenosine diphosphate in the purine metabolism and downregulated L-glycerophosphocholine and upregulated C16-dihydroceramide in the glycerophospholipid metabolism were associated with cellular antiproliferation and apoptosis, which directly influenced the cytotoxicity. Cell metabolomics was used to investigate the cytotoxicity mechanism of the pharmaceutical co-crystal, providing an effective and innovative method for clarifying the synergistic mechanism of API and CCF in co-crystal. [ABSTRACT FROM AUTHOR]

Abstract Introduction Recently, it was revealed that uric acid is a photosensitizer of reactions of nucleosides on irradiation with UV light at wavelengths longer than 300 nm, and two products generated from 2′-deoxycytidine were identified. In the present study, UV reactions of acetylated derivatives of 2′-deoxyguansoine and 2′-deoxyadenosine were conducted and their products were identified. Findings Each reaction of 3′,5′-di-O-acetyl-2′-deoxyguansoine or 3′,5′-di-O-acetyl-2′-deoxyadenosine with UV light at wavelengths longer than 300 nm in the presence of uric acid generated several products. The products were separated by HPLC and identified by comparing UV and MS spectra of the products with previously reported values. The major products were spiroiminodihydantoin, imidazolone, and dehydro-iminoallantoin nucleosides for 3′,5′-di-O-acetyl-2′-deoxyguansoine, and an adenine base and a formamidopyrimidine nucleoside for 3′,5′-di-O-acetyl-2′-deoxyadenosine. Conclusions If these damages caused by uric acid with sunlight occur in DNA of skin cells, mutations may arise. We should pay attention to the genotoxicity of uric acid in terms of DNA damage to dGuo and dAdo sites mediated by sunlight.

The research on DNA adduct 8-OHdG formation is performed by reacting 2'-deoxyguanosine and H2O2 with acrylamide (AA) and TBHQ compounds that were exposed to UVA light. The 8-OHdG forming test was conducted at various incubation times (5 h and 7 h) and pH variations (7.4 and 8.4). The 8-OHdG formation was analyzed using a reversed-phase HPLC instrument using a buffer solution of sodium phosphate pH 6.7: methanol (85:15) as eluent. The results showed that samples containing TBHQ and acrylamide (AA) produced 8-OHdG and shows synergistic and antagonistic effects. The 8-OHdG level of mixing acrylamide (AA) and TBHQ compounds increased significantly when exposed to UVA light. Samples incubated with UVA exposure had higher levels of 8-OHdG than samples without UVA exposure. The longer the incubation time, the greater the 8-OHdG content was produced. At pH 8.4, most of the samples resulted in greater 8-OHdG formation when compared to samples with the same mixture at pH 7.4. Samples with the greatest 8-OHdG formation results were found in samples containing 2'-deoxyguanosine, acrylamide (AA), TBHQ, and H2O2 at pH 8.4 with UVA light irradiation for 7h [ABSTRACT FROM AUTHOR]

Nanomaterials or nanoparticles are commonly used in the cosmetics, medicine, and food industries. Many researchers studied the possible side effects of several nanoparticles including aluminum oxide (Al2O3-nps) and zinc oxide nanoparticles (ZnO-nps). Although, there is limited information available on their direct or side effects, especially on the brain, heart, and lung functions. This study aimed to investigate the neurotoxicity, cardiotoxicity, and lung toxicity induced by Al2O3-nps and ZnO-nps or in combination via studying changes in gene expression, alteration in cytokine production, tumor suppressor protein p53, neurotransmitters, oxidative stress, and the histological and morphological changes. Obtained results showed that Al2O3-nps, ZnO-nps and their combination cause an increase in 8-hydroxy-2´-deoxyguanosine (8-OHdG), cytokines, p53, oxidative stress, creatine kinase, norepinephrine, acetylcholine (ACh), and lipid profile. Moreover, significant changes in the gene expression of mitochondrial transcription factor-A (mtTFA) and peroxisome proliferator activator receptorgamma-coactivator-1α (PGC-1α) were also noted. On the other hand, a significant decrease in the levels of antioxidant enzymes, total antioxidant capacity (TAC), reduced glutathione (GSH), paraoxonase 1 (PON1), neurotransmitters (dopamine – DA, and serotonin – SER), and the activity of acetylcholine esterase (AChE) in the brain, heart, and lung were found. Additionally, these results were confirmed by histological examinations. The present study revealed that the toxic effects were more when these nanoparticle doses are used in combination. Thus, Al2O3-nps and ZnO-nps may behave as neurotoxic, cardiotoxic, and lung toxic, especially upon exposure to rats in combination. [ABSTRACT FROM AUTHOR]

Many cancers appear to activate intrinsic antioxidant systems as a means to counteract oxidative stress. Some cancers, such as clear cell renal cell carcinoma (ccRCC), require exogenous glutamine for growth and exhibit reprogrammed glutamine metabolism, at least in part due to the glutathione pathway, an efficient cellular buffering system that counteracts reactive oxygen species and other oxidants. We show here that ccRCC xenograft tumors under the renal capsule exhibit enhanced oxidative stress compared with adjacent normal tissue and the contralateral kidney. Upon glutaminase inhibition with CB-839 or BPTES, the RCC cell lines SN12PM-6-1 (SN12) and 786-O exhibited decreased survival and pronounced apoptosis associated with a decreased GSH/GSSG ratio, augmented nuclear factor erythroid-related factor 2, and increased 8-oxo-7,8-dihydro-2'-deoxyguanosine, a marker of DNA damage. SN12 tumor xenografts showed decreased growth when treated with CB-839. Furthermore, PET imaging confirmed that ccRCC tumors exhibited increased tumoral uptake of 18F-(2S,4R)4-fluoroglutamine compared with the kidney in the orthotopic mouse model. This technique can be utilized to follow changes in ccRCC metabolism in vivo Further development of these paradigms will lead to new treatment options with glutaminase inhibitors and the utility of PET to identify and manage patients with ccRCC who are likely to respond to glutaminase inhibitors in the clinic. Cancer Res; 77(23); 6746-58. ©2017 AACR.

Deoxyguanosine kinase deficiency is one genetic cause of mtDNA depletion syndrome. Its major phenotypes include neonatal/infantile-onset hepatocerebral disease, isolated hepatic disease and myopathic disease. In this retrospective study, we seek to describe the natural history of deoxyguanosine kinase deficiency and identify any genotype-phenotype correlations. Retrospective literature search and collation of data from genetically confirmed cases of deoxyguanosine kinase deficiency. 173 cases of DGUOK deficiency were identified. Neonatal/infantile-onset hepatocerebral disease accounted for 128 (74%) of cases. Isolated liver disease was seen in 36 (21%) and myopathic disease in 9 (5%) of cases. The most frequently involved systems were liver (98%), brain (75%), growth (46%) and gastrointestinal tract (26%). Infantile-onset disease typically presented with cholestatic jaundice and lactic acidosis. Neurological involvement included hypotonia, nystagmus and developmental delay with MRI brain abnormalities in about half of cases. Missense variants accounted for 48% of all pathogenic variants while variants resulting in truncated transcripts accounted for 39%. Prognosis was poor, especially for neonatal/ infantile-onset hepatocerebral disease for which 1 year survival was 11%. Twenty-three patients received liver transplants, of whom 12 died within 2 years of transplant. Patients with two truncating variants had a higher risk of death and were more likely to have the neonatal/infantile-onset hepatocerebral disease phenotype. No blood biomarker predictive of neurological involvement was identified. Earlier onset correlated with increased mortality. There is a narrow window for therapeutic intervention. For the hepatocerebral disease phenotype, median age of onset was 1 month while the median age of death was 6.5 months implying rapid disease progression. [ABSTRACT FROM AUTHOR]

N,O‐Diacetyl tyrosine and 3‐(4‐hydroxy‐phenyl)‐propanoic acid were converted into phosphoramidite derivatives and introduced to the 5′‐end of oligonucleotides. The resulting oligonucleotides exhibiting a 4‐hydroxyphenyl alkyl group were conjugated with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione as a model of a Y‐click reaction. The reaction is fast (<1 h) and efficient (>90 %). A partial side reaction occurred at the C8 position of deoxyguanosine in single‐stranded oligonucleotides. This side reaction does not take place on the G quadruplex and double‐stranded oligonucleotides and when N2 position of guanine is protected. This Y‐click reaction could be applied to 1,2,4‐triazoline‐3,5‐dione derivatives displaying a fluorescent dye, a carbohydrate or orthogonal functions (alkyne, azide, ketone or maleimide) for the labelling of oligonucleotides. [ABSTRACT FROM AUTHOR]

Objective: Oxidative stress has been shown to play a role in the pathophysiology of several diseases, making it a popular yet contentious research area. There is some evidence that selective melanocyte destruction may have developed in vitiligo patients as a result of elevated oxidative stress. The purpose of this study is to investigate the impact of oxidative stress on lipid, protein, and nucleic acid metabolism in vitiligo patients. Methods: We used ELISA method to measure serum oxidative stress markers in patients with generalized vitiligo who had newly formed lesions in the previous three months but had not been treated, as well as healthy controls. Malondialdehyde (MDA), 2,4-dinitrophenyl hydrazone (DNPH), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and uncoupling protein 2 (UCP2) levels were measured to assess the influence of reactive oxygen derivatives on lipid, protein, nucleic acid metabolism, and mitochondria, respectively. Results: The study included 84 participants, including 64 active generalized vitiligo patients and 20 healthy controls with similar age and gender distribution. In the serum of vitiligo patients, we detected significantly lower levels of MDA (ng/mL, mean±SD=12±19; 33.4±35.9), DNPH (ng/mL, mean±SD=2±3.1; 6±7.4), 8-OHdG (ng/mL, mean±SD=11.7±17.9; 32.7±37) and UCP2 (ng/mL, mean±SD=8.7±13.7; 21.5±28.4. Conclusions: Although there is significant evidence that oxidative stress plays a role in the pathophysiology of vitiligo, the studies should be interpreted cautiously due to the heterogeneity in the methodology, complexity of the oxidative stress pathways, and potential publication bias. Large-scale studies using a standardized methodology are required to determine how significant oxidative stress is in the core pathophysiology of vitiligo and which pathways it primarily affects. [ABSTRACT FROM AUTHOR]

Objective: In this study, we aimed to examine thiol/disulfide homeostasis and oxidative DNA damage in patients with OCD and compare them with healthy controls. Methods: Thirty-five patients previously diagnosed with OCD in Van Yuzuncu Yil University Department of Psychiatry and thirty-three healthy volunteers were included in the study. The severity of the symptoms was measured using the Yale-Brown Obsessive-Compulsive Scale. Five ml of blood samples were taken from the patient and control groups. The samples were stored at appropriate conditions until use. Leukocyte DNA was isolated and the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) and deoxyguanosine were detected to assess the oxidative DNA damage. The level of oxidative DNA damage was expressed as 8-OHdG/106dG. Total thiol/native thiol levels were measured for thiol/disulfide homeostasis. The level of disulfide was determined by subtracting the native thiol value from the total thiol value and the result was divided by two. Results were given as percentages. Results: The total and native thiol levels in patients with OCD were significantly lower, and the disulfide levels were significantly higher in patients with OCD than healthy control subjects. In addition, 8-OHdG, an indicator of DNA damage, was significantly lower in the control group compared to the patient group. Conclusion: Increased levels of disulfide/native thiol and disulfide/total thiol in patients with OCD show that levels of oxidative stress were elevated and therefore, higher 8-OHdG levels in patients with OCD is a marker of oxidative DNA damage. [ABSTRACT FROM AUTHOR]

Deoxyguanosine kinase (dGK) is reported responsible for the phosphorylation of deoxyadenosine (dA) and deoxyguanosine (dG) in the mitochondrial purine salvage pathway. Antiviral nucleoside analogs known as nucleoside reverse transcriptase inhibitors (NRTIs) must be phosphorylated by host enzymes for the analog to become active. We address the possibility that NRTI purine analogs may be competitive inhibitors of dGK. From a group of such analogs, we demonstrate that entecavir (ETV) competitively inhibited the phosphorylation of dG and dA in rat mitochondria. Mitochondria from the brain, heart, kidney, and liver showed a marked preference for phosphorylation of dG over dA (10-30-fold) and ETV over dA (2.5-4-fold). We found that ETV inhibited the phosphorylation of dG with an IC50 of 15.3 ± 2.2 μM and that ETV and dG were both potent inhibitors of dA phosphorylation with IC50s of 0.034 ± 0.007 and 0.028 ± 0.006 μM, respectively. In addition, the phosphorylation of dG and ETV followed Michaelis-Menten kinetics and each competitively inhibited the phosphorylation of the other. We observed that the kinetics of dA phosphorylation were strikingly different from those of dG phosphorylation, with an exponentially lower affinity for dGK and no effect of dA on dG or ETV phosphorylation. Finally, in an isolated heart perfusion model, we demonstrated that dG, dA, and ETV were phosphorylated and dG phosphorylation was inhibited by ETV. Taken together, these data demonstrate that dGK is inhibited by ETV and that the primary role of dGK is in the phosphorylation of dG rather than dA. [ABSTRACT FROM AUTHOR]

Background: The aim of the study was to determine the prognostic value of 8-oxo-2'-deoxyguanosine (8-OHdG) plasma levels for cardiovascular complications (CVC) development in hypertension (HTN) and type 2 diabetes mellitus (T2DM) comorbidity. Material and methods: One hundred fifty-six patients (mean age 61.71 ± 0.87 years) with the combined course of HTN stage II and T2DM (group 1) and 100 non-diabetic patients with HTN stage II (mean age 60.59 ± 0.87 years, group 2) were examined. Lipid, carbohydrate metabolism, plasma insulin, plasma 8-OHdG (by ELISA), blood pressure levels were measured. Observation period was 12 months. Results: Plasma levels of 8-OHdG in the patients' groups were significantly higher than in the controls (p < 0.001), in the group 1 higher than in group 2 (15.37 ± 0.27 ng/L vs. 14.00 ± 0.29 ng/L, respectively, p = 0.002). Plasma levels of 8-OHdG in group-2 patients who developed cardiovascular complications during observation period were significantly higher than in those without cardiovascular complications (16.47 ± 0.62 ng/L vs. 15.11 ± 0.29 ng/L, respectively, p = 0.046). The ROC analysis made it possible to propose the 8-OHdG plasma level = 15.68 ng/L as an identifier for the cardiovascular complications in patients with studied comorbidity. In group 1, in patients with 8-OHdG plasma level = 15.68 ng/L such cardiovascular risk factors as total cholesterol (TC) (p = 0.034), low density lipoprotein cholesterol (LDL-C) (p = 0.035), systolic blood pressure (p = 0.022), HOMA-IR (p = 0.046) were significantly higher compared with those whose level of this indicator was < 15.68 ng/L. Conclusion: Determination of the plasma 8-OHdG allows not only for assessment of the severity of oxidative stress, but also for determination of the course and prognosis in comorbidity of HTN and T2DM. [ABSTRACT FROM AUTHOR]

Adenosine synthase A (AdsA) is a key virulence factor of Staphylococcus aureus , a dangerous microbe that causes fatal diseases in humans. Together with staphylococcal nuclease, AdsA generates deoxyadenosine (dAdo) from neutrophil extracellular DNA traps thereby igniting caspase-3-dependent cell death in host immune cells that aim at penetrating infectious foci. Powered by a multi-technological approach, we here illustrate that the enzymatic activity of AdsA in abscess-mimicking microenvironments is not restricted to the biogenesis of dAdo but rather comprises excessive biosynthesis of deoxyguanosine (dGuo), a cytotoxic deoxyribonucleoside generated by S. aureus to eradicate macrophages of human and animal origin. Based on a genome-wide CRISPR-Cas9 knock-out screen, we further demonstrate that dGuo-induced cytotoxicity in phagocytes involves targeting of the mammalian purine salvage pathway-apoptosis axis, a signaling cascade that is concomitantly stimulated by staphylococcal dAdo. Strikingly, synchronous targeting of this route by AdsA-derived dGuo and dAdo boosts macrophage cell death, indicating that S. aureus multiplexes death-effector deoxyribonucleosides to maximize intra-host survival. Overall, these data provide unique insights into the cunning lifestyle of a deadly pathogen and may help to design therapeutic intervention strategies to combat multidrug-resistant staphylococci. [ABSTRACT FROM AUTHOR]

Adenosine synthase A (AdsA) is a key virulence factor of Staphylococcus aureus, a dangerous microbe that causes fatal diseases in humans. Together with staphylococcal nuclease, AdsA generates deoxyadenosine (dAdo) from neutrophil extracellular DNA traps thereby igniting caspase-3-dependent cell death in host immune cells that aim at penetrating infectious foci. Powered by a multi-technological approach, we here illustrate that the enzymatic activity of AdsA in abscess-mimicking microenvironments is not restricted to the biogenesis of dAdo but rather comprises excessive biosynthesis of deoxyguanosine (dGuo), a cytotoxic deoxyribonucleoside generated by S. aureus to eradicate macrophages of human and animal origin. Based on a genome-wide CRISPR-Cas9 knock-out screen, we further demonstrate that dGuo-induced cytotoxicity in phagocytes involves targeting of the mammalian purine salvage pathway-apoptosis axis, a signaling cascade that is concomitantly stimulated by staphylococcal dAdo. Strikingly, synchronous targeting of this route by AdsA-derived dGuo and dAdo boosts macrophage cell death, indicating that S. aureus multiplexes death-effector deoxyribonucleosides to maximize intra-host survival. Overall, these data provide unique insights into the cunning lifestyle of a deadly pathogen and may help to design therapeutic intervention strategies to combat multidrug-resistant staphylococci.

Postmenopausal osteoporosis (PO) is a major public health issue which affects a large fraction of elderly women. Emerging in vitro evidence suggests a central role of oxidative stress (OxS) in postmenopausal osteoporosis (PO) development. Contrariwise, the human studies on this topic are still scarce and inconclusive. In the attempt to address this issue, we sought to determine if OxS, as assessed by 8-hydroxy-2-deoxyguanosine (8-OHdG), may influence the level of receptor activator of nuclear factor-κb ligand (RANKL)/osteoprotegerin (OPG) ratio (a central regulator of bone metabolism) in a sample (n = 124), including postmenopausal women with osteoporosis, osteopenia and normal bone mass density (BMD). The most striking result that emerged in our study was the independent and positive (beta = 0.449, p = 0.004, and R(2) = 0.185) association between the OxS marker and RANKL/OPG ratio which was found in osteopenic but not in the other 2 sample groups. If confirmed by longitudinal studies, our findings would suggest that OxS is implicated in the derangement of bone homeostasis which precedes PO development. In line with these considerations, antioxidant treatment of postmenopausal women with moderately low BMD might contribute to preventing PO and related complications.

Introduction: Recently, it was revealed that uric acid is a photosensitizer of reactions of nucleosides on irradiation with UV light at wavelengths longer than 300 nm, and two products generated from 2′-deoxycytidine were identified. In the present study, UV reactions of acetylated derivatives of 2′-deoxyguansoine and 2′-deoxyadenosine were conducted and their products were identified. Findings: Each reaction of 3′,5′-di-O-acetyl-2′-deoxyguansoine or 3′,5′-di-O-acetyl-2′-deoxyadenosine with UV light at wavelengths longer than 300 nm in the presence of uric acid generated several products. The products were separated by HPLC and identified by comparing UV and MS spectra of the products with previously reported values. The major products were spiroiminodihydantoin, imidazolone, and dehydro-iminoallantoin nucleosides for 3′,5′-di-O-acetyl-2′-deoxyguansoine, and an adenine base and a formamidopyrimidine nucleoside for 3′,5′-di-O-acetyl-2′-deoxyadenosine. Conclusions: If these damages caused by uric acid with sunlight occur in DNA of skin cells, mutations may arise. We should pay attention to the genotoxicity of uric acid in terms of DNA damage to dGuo and dAdo sites mediated by sunlight. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of the study was to examine the possible effects of curcumin on the formation of neomucosa in parietal peritoneum which was applied as a patch for terminal ileal defect in rats. Methods: Sixteen male Wistar Hannover rats were split into two groups. The control group was injected with saline and curcumin (2 mL/kg/day, by gavage) was given to the experimental group. In both groups, amounts of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA), the activities of glutathione peroxidase and superoxide dismutase were determined in serum. The development of neomucosa formation was examined morphologically. Results: Serum antioxidant levels and glutathione peroxidase activity in rats given curcumin were significantly higher than those of the control group (p<0.05). The levels of oxidative markers (MDA and 8-OHdG) in rats given curcumin were significantly lower than those of the control group (p<0.05). In the histopathological examination, 62.5% of rats in the curcumin group showed formation of neomucosa while 37.5% of control rats showed neomucosa. Conclusion: The use of curcumin in rats with terminal ileal defect enhanced the formation of neomucosa by decreasing the oxidation level and increasing the antioxidation level. Curcumin may be used in the patients with short bowel syndrome to increase the absorption surface area. [ABSTRACT FROM AUTHOR]

Oxidative stress (OS) is a situation that occurs as a result of un-equilibrium between reactive oxygen species (ROS) formation and the antioxidant defence system. 8-hydroxy-2-deoxyguanosine (8-OHdG), an oxidized form of deoxyguanosine, is found in higher levels in aging oocytes. In this cross-sectional study, we aimed to evaluate the effect of 8-OHdG on the intracytoplasmic sperm injection (ICSI). Follicular fluid (FF) samples were taken after removing the oocyte for later analysis of 8-OHdG. The couples participants were categorized according to the cause of subfertility into three groups (female factor, malefactor, and unexplained infertility). Further division according to pregnancy state was done to evaluate the precise role of 8-OHdG on pregnancy state and ICSI outcome. Result : This study showed that the 8-OHdG levels significantly higher in non-pregnant women (p < 0.05). Correlation study showed that 8-OHdG level in follicular fluid is negatively correlating with the number of retrieved oocytes, metaphase two oocytes (MII), fertilized oocytes (2PN = two pronuclei), cleaved zygotes, good quality embryos, and the difference was statistically significant (p < 0.05). Conclusion: The study revealed that the 8-OHdG level in follicular fluid negatively influences ICSI outcome and it is higher in non-pregnant women. [ABSTRACT FROM AUTHOR]

BackgroundPreclinical and epidemiologic studies suggest chemopreventive effects of green tea (GT) and black tea (BT) in prostate cancer. In the current study we determined the effect of GT and BT consumption on biomarkers related to prostate cancer development and progression.MethodsIn this exploratory, open label, phase II trial 113 men diagnosed with prostate cancer were randomized to consume six cups daily of brewed GT, BT or water (control) prior to radical prostatectomy (RP). The primary endpoint was prostate tumor markers of cancer development and progression determined by tissue immunostaining of proliferation (Ki67), apoptosis (Bcl-2, Bax, Tunel), inflammation (nuclear and cytoplasmic nuclear factor kappa B [NFκB]) and oxidation (8-hydroxydeoxy-guanosine [8OHdG]). Secondary endpoints of urinary oxidation, tea polyphenol uptake in prostate tissue, and serum prostate specific antigen (PSA) were evaluated by high performance liquid chromatography and ELISA analysis.ResultsNinety three patients completed the intervention. There was no significant difference in markers of proliferation, apoptosis and oxidation in RP tissue comparing GT and BT to water control. Nuclear staining of NFκB was significantly decreased in RP tissue of men consuming GT (P = 0.013) but not BT (P = 0.931) compared to water control. Tea polyphenols were detected in prostate tissue from 32 of 34 men consuming GT but not in the other groups. Evidence of a systemic antioxidant effect was observed (reduced urinary 8OHdG) only with GT consumption (P = 0.03). GT, but not BT or water, also led to a small but statistically significant decrease in serum prostate-specific antigen (PSA) levels (P = 0.04).ConclusionGiven the GT-induced changes in NFκB and systemic oxidation, and uptake of GT polyphenols in prostate tissue, future longer-term studies are warranted to further examine the role of GT for prostate cancer prevention and treatment, and possibly for other prostate conditions such as prostatitis.

Diabetes mellitus disease (DMD) is the most rapidly growing chronic metabolic disease in the world. Recent evidence reveals that high blood glucose is associated with cancer risk in diabetic patients. In diabetes type 2 patients, based on HbA1c-levels and another factor to predict possible cancer risk. The current study aims to analyze DNA oxidation biomarkers by measuring 8-hydroxy-22-deoxyguanosine (8-OHdG). A total of 119 patients previously diagnosed with type 2 diabetes (53 male and 66 female) were enrolled in this study from a local diabetes clinic (Baghdad). The control group included 57 nondiabetic healthy volunteers (26 male, 31 females). BMI was calculated as weight (W) in kilograms divided by the square of height (H) in meters) and four to five milliliters of venous blood were withdrawn from each participant (patients and control) via venipuncture under sterile conditions. Glycated hemoglobin was measured by using spinreact kits (Spin). Urine samples were collected from each participant (patients and controls) to analyze The 8-OHdG concentrations in urine using 8-OHdG (8- Hydroxydeoxyguanosine) ELISA Kit. The HbA1c value in patients was significantly higher than those of control (P<0.0001). The 8-OHdG value in urine samples of diabetic patients was higher than in the control group. However, the differences between groups (patients and control) were statistically not significant (P>0.05). The current study’s finding does not approve the hypothesis that oxidative stress and its subsequent genomic damage are growing in diabetics patients. Also, the present study does not express any significant associations between HbA1c value and oxidative markers(8-OHdG ). Most previous studies matched healthy individuals to type 2 diabetes patients and could identify induced oxidative damage in type 2 diabetes patients. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polarization of the water environment reduces double-ionization energies and facilitates the hole transfer. • Double ionization in solutions is independent of the counterion. • The environment screens the contribution of the phosphate group. • The barrier height of bond break suggests that the scission of the glycosidic bond could be a potential damaged pathway. Computations were carried out to investigate the mechanism of double-ionization damage for deoxyguanosine nucleotide. The results reveal that the polarization of the water environment reduces double-ionization energies and facilitates the hole transfer. Double ionization in solutions is independent of the counterion. The environment screens the contribution of the phosphate group. After double ionization, cleavage of the C-N glycosidic bond is a barrierless process in the gas phase. The barrier height of bond break is ∼ 4.0 kcal/mol in solutions. The C-N scission could be a potential damaged pathway. The counterion has a minor effect on the bond rupture. [ABSTRACT FROM AUTHOR]

The 8-hydroxy-deoxyguanosine (8-OHdG) is one of the customary products of oxidized DNA. The purpose of this study was to compare salivary and plasma 8-OHdG concentrations in a group of chronic periodontitis patients to those measured in a group of patients with healthy periodontium, as well as to determine the impact of periodontal therapy on 8-OHdG concentrations in saliva and plasma in chronic periodontitis patients. The study sample comprised of 24 patients with chronic periodontitis and 16 periodontally healthy individuals. Plaque index, gingival index, papilla bleeding index, probing depth and clinical attachment level were indices used to determine patient periodontal status. Salivary and plasma 8-OHdG concentrations were determined by ELISA method. The salivary 8-OHdG concentration was statistically significantly higher in the group of periodontitis patients compared to periodontally healthy subjects. After initial periodontal therapy, the 8-OHdG concentration in saliva was significantly reduced in the periodontitis group (p=0.021). Differences in plasma 8-OHdG concentrations between the two groups did not reach statistical significance and no significant changes were noted in the periodontitis group following initial periodontal therapy. A higher salivary 8-OHdG concentration reflects increased oxidative stress caused by periodontal disease. Initial periodontal therapy may be helpful in reducing salivary 8-OHdG concentrations in chronic periodontitis patients.

A systematic study involving the use and optimization of gas-phase modifiers in quantitative differential mobility-mass spectrometry (DMS-MS) analysis is presented using nucleoside-adduct biomarkers of DNA damage as an important reference point for analysis in complex matrices. Commonly used polar protic and polar aprotic modifiers have been screened for use against two deoxyguanosine adducts of DNA: N-(deoxyguanosin-8-yl)-4-aminobiphenyl (dG-C8-4-ABP) and N-(deoxyguanosin-8-y1)-2-amino-l-methyl-6-phenylimidazo[4,5-b]pyridine (dG-C8-PhIP). Particular attention was paid to compensation voltage (CoV) shifts, peak shapes, and product ion signal intensities while optimizing the DMS-MS conditions. The optimized parameters were then applied to rapid quantitation of the DNA adducts in calf thymus DNA. After a protein precipitation step, adduct levels corresponding to less than one modification in 10(6) normal DNA bases were detected using the DMS-MS platform. Based on DMS fundamentals and ab initio thermochemical results, we interpret the complexity of DMS modifier responses in terms of thermal activation and the development of solvent shells. At very high bulk gas temperature, modifier dipole moment may be the most important factor in cluster formation and cluster geometry, but at lower temperatures, multi-neutral clusters are important and less predictable. This work provides a useful protocol for targeted DNA adduct quantitation and a basis for future work on DMS modifier effects.

Background/Aim: The aim of the study was to assess the impact of nano-, micro-, and macro-sized-genistein on the growth and development of neoplasms in rats with mammary cancer. Additionally, the effect on the kinetics of changes (9-11-17-20 week of a rat's life) in the levels of methyl derivatives: 1-methyladenine, 3-methyladenine, 7-methylguanine, 1-methylguanine, 1-methyladenosine, 7- methylguanosine, O-methyl-guanosine and N6-methyl-2'-deoxyguanosine in the urine of rats was analyzed. Materials and Methods: Female Sprague-Dawley rats divided into 4 groups were used in the study. Animals were fed only a control diet or diets supplemented with the nano-, micro- and macro-sized genistein. To induce the mammary adenocarcinoma, rats were treated with 7,12-dimethylbenz[a]anthracene (DMBA). Modified nucleosides were determined by a high-performance liquid chromatography coupled to mass spectrometry method (LC-MS/MS). Results: The supplementation of the diet of animals with genistein resulted in an increase in the excretion of methylated derivatives in the urine of rats. In the animals receiving standard diet, the levels of methyl derivatives increased during the study or remained relatively low. In the case of animals whose diet was supplemented with the various forms of genistein, the levels of methylated derivatives were very high from the beginning. Conclusion: High levels of methyl derivatives can influence carcinogenesis. [ABSTRACT FROM AUTHOR]

Pomegranates slow prostate cancer xenograft growth and prolong prostate-specific antigen (PSA) doubling times in single-arm human studies. Pomegranates' effects on human prostate tissue are understudied. We hypothesized that orally administered pomegranate extract (POMx; Pom Wonderful) would lower tissue 8-hydroxy-2'-deoxyguanosine (8-OHdG), an oxidative stress biomarker. Seventy men were randomized to two tablets, POMx or placebo, daily up to four weeks before radical prostatectomy. Tissue was analyzed for intraprostatic urolithin A, a pomegranate metabolite, benign and malignant 8-OHdG, and cancer pS6 kinase, NF-κB, and Ki67. Primary endpoint was differences in 8-OHdG, and the study was powered to detect 35% reduction. POMx was associated with 16% lower benign tissue 8-OHdG (P = 0.095), which was not statistically significant. POMx was well tolerated with no treatment-related withdrawals. There were no differences in baseline clinicopathological features between arms. Urolithin A was detected in 21 of the 33 patients in the POMx group versus 12 of the 35 in the placebo group (P = 0.031). Cancer pS6 kinase, NF-κB, Ki67, and serum PSA changes were similar between arms. POMx before surgery results in pomegranate metabolite accumulation in prostate tissues. Our primary endpoint in this modest-sized short-term trial was negative. Future larger longer studies are needed to more definitively test whether POMx reduces prostate oxidative stress, as well as further animal testing to better understand the multiple mechanisms through which POMx may alter prostate cancer biology.

IntroductionDuctal carcinoma in situ (DCIS) is a noninvasive breast cancer wherein malignant cells are confined within a ductal lobular unit. Although less than half the cases of DCIS will progress to invasive disease, most women are treated aggressively with surgery, radiation, and/or hormone therapy due to the inability to clinically evaluate the extent and location of the disease. Intraductal therapy, in which a drug is administered directly into the mammary duct through the nipple, is a promising approach for treating DCIS, but the feasibility of instilling drug into a diseased duct has not been established.Patients and methodsFour to 6 weeks before their scheduled surgery, 13 women diagnosed with DCIS were subjected to cannulation of the affected duct. After both the absence of perforation and presence of dye in the duct were confirmed by ductogram, pegylated liposomal doxorubicin was instilled. Histopathologic assessment was performed after surgery to assess the treatment effects.ResultsOf the 13 women enrolled in the study, 6 had their DCIS duct successfully cannulated without perforation and instilled with the drug. The treatment was well tolerated, and no serious adverse events have been reported. Biomarker studies indicated a general decrease in Ki-67 levels but an increase in annexin-1 and 8-hydroxydeoxyguanosine in the lumen of DCIS-containing ducts, which suggests a local response to pegylated liposomal doxorubicin treatment.ConclusionsIntraductal therapy offers a nonsurgical strategy to treat DCIS at the site of disease, potentially minimizing the adverse effects of systemic treatment while preventing development of invasive cancer.

We compared the therapeutic effects of topical 8-oxo-2′-deoxyguanosine (8-oxo-dG) and corticosteroid in a murine ocular alkali burn model. (n = 128) The corneal alkali burn model was established by applying 0.1 N sodium hydroxide (NaOH), followed by treatment with 8-oxo-dG, 0.1% fluorometholone (FML), 1% prednisolone acetate (PDE), or phosphate-buffered saline (PBS) twice daily. One week later, the clinical and histological status of the cornea were assessed. Transcript levels of inflammatory cytokines and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase as well as the levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the cornea, were assayed. The 8-oxo-dG and PDE groups showed marked improvements in corneal integrity and clarity when compared with the PBS group (each p < 0.01). The numbers of cells stained for neutrophil elastase and F4/80-positive inflammatory cells were significantly decreased, with levels of interleukin(IL)-1β, IL-6, tumor necrosis factor(TNF)-α, and total ROS/RNS amounts markedly reduced in the 8-oxo-dG, FML, and PDE groups (each p < 0.05). Levels of NADPH oxidase type 2 and 4 were substantially more repressed in the 8-oxo-dG-treated group than in the PDE-treated group (each p < 0.05). Topical 8-oxo-dG showed excellent therapeutic effects that were comparable with those treated with topical PDE in a murine ocular alkali burn model. [ABSTRACT FROM AUTHOR]

To counteract the deleterious effects of DNA damage, cells are equipped with specialized polymerases to bypass DNA lesions. Previous biochemical studies revealed that DinB family DNA polymerases, including Escherichia coli DNA polymerase IV and human DNA polymerase κ, efficiently incorporate the correct nucleotide opposite some N(2)-modified 2'-deoxyguanosine derivatives. Herein, we used shuttle vector technology and demonstrated that deficiency in Polk or Poli in mouse embryonic fibroblast (MEF) cells resulted in elevated frequencies of G→T and G→A mutations at N(2)-(1-carboxyethyl)-2'-deoxyguanosine (N(2)-CEdG) and N(2)-carboxymethyl-2'-deoxyguanosine (N(2)-CMdG) sites. Steady-state kinetic measurements revealed that human DNA polymerase ι preferentially inserts the correct nucleotide, dCMP, opposite N(2)-CEdG lesions. In contrast, no mutation was found after the N(2)-CEdG- and N(2)-CMdG-bearing plasmids were replicated in POLH-deficient human cells or Rev3-deficient MEF cells. Together, our results revealed that, in mammalian cells, both polymerases κ and ι are necessary for the error-free bypass of N(2)-CEdG and N(2)-CMdG. However, in the absence of polymerase κ or ι, other translesion synthesis polymerase(s) could incorporate nucleotide(s) opposite these lesions but would do so inaccurately.