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Aims/hypothesis: This secondary analysis aimed to investigate the effects of a 12 months intensive exercise-based lifestyle intervention on systemic markers of oxidative stress in persons with type 2 diabetes. We hypothesized lifestyle intervention to be superior to standard care in decreasing levels of oxidative stress. Methods: The study was based on the single-centre, assessor-blinded, randomised, controlled U-turn trial (ClinicalTrial.gov NCT02417012). Persons with type 2 diabetes ˂ 10 years, ˂ 3 glucose lowering medications, no use of insulin, BMI 25–40 kg/m2 and no severe diabetic complications were included. Participants were randomised (2:1) to either intensive exercise-based lifestyle intervention and standard (n = 64) or standard care alone (n = 34). Standard care included individual education in diabetes management, advice on a healthy lifestyle and regulation of medication by a blinded endocrinologist. The lifestyle intervention included five to six aerobic exercise sessions per week, combined with resistance training two to three times per week and an adjunct dietary intervention aiming at reduction of ∼500 kcal/day (month 0–4). The diet was isocaloric from months 5–12. The primary outcome of this secondary analysis was change in oxidative stress measured by 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and secondarily in 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), as markers of RNA and DNA oxidation, respectively, from baseline to 12-months follow-up. Results: A total of 77 participants, 21 participants receiving standard care and 56 participants receiving the lifestyle intervention, were included in the analysis. Mean age at baseline was 54.1 years (SD 9.1), 41% were women and mean duration of type 2 diabetes was 5.0 years (SD 2.8). From baseline to follow-up the lifestyle group experienced a 7% decrease in 8-oxoGuo (−0.15 nmol/mmol creatinine [95% CI -0.27, −0.03]), whereas standard care conversely was associated with a 8.5% increase in 8-oxoGuo (0.19 nmol/mmol creatinine [95% CI 0.00, 0.40]). The between group difference in 8-oxoGuo was −0.35 nmol/mmol creatinine [95% CI -0.58, −0.12,], p = 0.003. No between group difference was observed in 8-oxodG. Conclusion/interpretation: A 12 months intensive exercise-based lifestyle intervention was associated with a decrease in RNA, but not DNA, oxidation in persons with type 2 diabetes.

Purpose: The purpose of this study was to investigate whether specific combinations of polymorphisms in genes encoding proteins involved in 5-fluorouracil (5-FU) pharmacokinetics and pharmacodynamics are associated with increased risk of treatment-induced toxicity.Experimental Design: We analyzed two cohorts of 161 and 340 patients, the exploration and validation cohort, respectively. All patients were treated similarly with 5-FU–based adjuvant chemotherapy. We analyzed 13 functional polymorphisms and applied a four-fold analysis strategy using individual polymorphisms, haplotypes, and phenotypic enzyme activity or expression classifications based on combinations of functional polymorphisms in specific genes. Furthermore, multifactor dimensionality reduction analysis was used to identify a genetic interaction profile indicating an increased risk of toxicity.Results: Alleles associated with low activity of methylene tetrahydrofolate reductase (MTHFR) were associated with decreased risk of toxicity [ORExploration 0.39 (95% CI: 0.21–0.71, P = 0.003), ORValidation 0.63 (95% CI: 0.41–0.95, P = 0.03)]. A specific combination of the MTHFR 1298A>C and thymidylate synthase (TYMS) 3′-UTR (untranslated region) ins/del polymorphisms was significantly associated with increased toxicity in both cohorts [ORExploration 2.40 (95% CI: 1.33–4.29, P = 0.003), ORValidation 1.81 (95% CI: 1.18–2.79, P = 0.007)]. The specific combination was also associated with increased cumulative incidence and earlier occurrence of severe toxicity during treatment.Conclusions: Our results indicate that MTHFR activity and a specific combination of the MTHFR 1298A>C and TYMS 3′-UTR ins/del polymorphisms are possible predictors of 5-FU treatment–related toxicity. Clin Cancer Res; 17(11); 3822–9. ©2011 AACR.

Supplementary Figure S1; Supplementary Tables S1-S4.

Objectives We evaluated the long-term stability of thyroid peroxidase antibody (anti-TPO). Methods In the Danish General Suburban Population Study (GESUS), serum samples were biobanked at −80 °C during 2010–2013. In a paired design with 70 subjects, we compared anti-TPO (30–198 U/mL) measured on fresh serum on Kryptor Classic in 2010–2011 (anti-TPOfresh) with anti-TPO remeasured on frozen serum (anti-TPOfrozen) on Kryptor Compact Plus in 2022. Both instruments used the same reagents and the anti-TPOn automated immunofluorescent assay, which was calibrated against the international standard NIBSC 66/387, based on the Time Resolved Amplified Cryptate Emission (TRACE) technology from BRAHMS. Values greater than 60 U/mL are regarded as positive in Denmark with this assay. Statistical comparisons included Bland-Altman, Passing-Bablok regression, and Kappa statistic. Results The mean follow-up time was 11.9 years (SD: 0.43). For anti-TPOfrozen vs. anti-TPOfresh, the line of equality was within the confidence interval of the absolute mean difference [5.71 (−0.32; 11.7) U/mL] and the average percentage deviation [+2.22% (−3.89%; +8.34%)]. The average percentage deviation of 2.22% did not exceed analytical variability. Passing-Bablok regression revealed both a statistically significant systematic and proportional difference: Anti-TPOfrozen=−22.6 + 1.22*(anti-TPOfresh). Frozen samples were correctly classified as positive in 64/70 (91.4%; Kappa=71.8%). Conclusions Anti-TPO serum samples in the range 30–198 U/mL were stable after 12-years of storage at −80 °C with an estimated nonsignificant average percentage deviation of +2.22%. This comparison is based on Kryptor Classic and Kryptor Compact Plus, which used identical assays, reagents, and calibrator, but for which the agreement in the range 30–198 U/mL is unclarified.

Formation of reactive oxygen species has been linked to the development of diabetes complications. Treatment with metformin has been associated with a lower risk of developing diabetes complications, including when used in combination with insulin. Metformin inhibits Complex 1 in isolated mitochondria and thereby decreases the formation of reactive oxygen species. Thus, we post-hoc investigated the effect of metformin in combination with different insulin regimens on RNA and DNA oxidation in individuals with type 2 diabetes. Four hundred and fifteen individuals with type 2 diabetes were randomized (1:1) to blinded treatment with metformin (1,000 mg twice daily) versus placebo and to (1:1:1) open-label biphasic insulin, basal-bolus insulin, or basal insulin therapy in a 2 × 3 factorial design. RNA and DNA oxidation were determined at baseline and after 18 months measured as urinary excretions of 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), respectively. Urinary excretion of 8-oxoGuo changed by +7.1% (95% CI: 0.5% to 14.0%, P = 0.03) following metformin versus placebo, whereas changes in 8-oxodG were comparable between intervention groups. Biphasic insulin decreased urinary excretion of 8-oxoGuo (within-group: −9.6% (95% CI: −14.4% to −4.4%)) more than basal-bolus insulin (within-group: 5.2% (95% CI: −0.5% to 11.2%)), P = 0.0002 between groups, and basal insulin (within-group: 3.7% (95% CI: −2.0% to 9.7%)), P = 0.0007 between groups. Urinary excretion of 8-oxodG decreased more in the biphasic insulin group (within-group: −9.9% (95% CI: −14.4% to −5.2%)) than basal-bolus insulin (within group effect: −1.2% (95% CI: −6.1% to 3.9%)), P = 0.01 between groups, whereas no difference was observed compared with basal insulin. In conclusion, eighteen months of metformin treatment in addition to different insulin regimens increased RNA oxidation, but not DNA oxidation. Biphasic insulin decreased both RNA and DNA oxidation compared with other insulin regimens.

Modifications of nucleic acids (DNA and RNA) from oxidative stress is a potential driver of aging per se and of mortality in age-associated medical disorders such as type 2 diabetes (T2D). In a human cohort, we found a strong prediction of all-cause mortality by a marker of systemic oxidation of RNA in patients with T2D (n = 2672) and in nondiabetic control subjects (n = 4079). The finding persisted after the adjustment of established modifiers of oxidative stress (including BMI, smoking, and glycated hemoglobin). In contrast, systemic levels of DNA damage from oxidation, which traditionally has been causally linked to both T2D and aging, failed to predict mortality. Strikingly, these findings were subsequently replicated in an independent general population study (n = 3649). The data demonstrate a specific importance of RNA damage from oxidation in T2D and general aging. Modifications of nucleic acids (DNA and RNA) from oxidative stress is a potential driver of aging per se and of mortality in age-associated medical disorders such as type 2 diabetes (T2D). In a human cohort, we found a strong prediction of all-cause mortality by a marker of systemic oxidation of RNA in patients with T2D (n = 2672) and in nondiabetic control subjects (n = 4079). The finding persisted after the adjustment of established modifiers of oxidative stress (including BMI, smoking, and glycated hemoglobin). In contrast, systemic levels of DNA damage from oxidation, which traditionally has been causally linked to both T2D and aging, failed to predict mortality. Strikingly, these findings were subsequently replicated in an independent general population study (n = 3649). The data demonstrate a specific importance of RNA damage from oxidation in T2D and general aging.

Oxidatively generated DNA damage is of paramount importance in a wide range of physiological and pathophysiological processes. Urinary 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) is often used as an outcome marker in studies on the role of oxidatively generated DNA damage, but its exact relation to intracellular damage levels and variations in DNA repair have been unclear. Using a new approach of quantitative kinetic modeling inspired by pharmacokinetics, we find evidence that in steady state - i.e. when systemic consequences of given change in damage or cellular removal rates have stabilized - the urinary excretion of 8-oxodG is closely correlated to rates of damage and intracellular 8-oxodG levels, but independent of the rate of cellular removal. Steady state was calculated to occur within approximately 12 h. A similar pattern was observed in a model of the corresponding RNA marker 8-oxo-7,8-dihydroguanosine (8-oxoGuo), but with steady-state occurring slower (up to 5 d). These data have significant implications for the planning of studies and interpretation of data involving urinary 8-oxodG/8-oxoGuo excretion as outcome.HighlightsThe kinetics of 8-oxodG/8-oxoGuo formation, removal and excretion were simulated in silico.The model was based on existing data on 8-oxodG/8-oxoGuo levels and removal/excretion rates.Intracellular 8-oxodG/8-oxoGuo was closely correlated with urinary excretion in steady state.Changes in removal rates did not influence urinary excretion of 8-oxodG/8-oxoGuo.

The effect of oral glutathione (GSH) supplementation was studied in obese subjects with and without type 2 diabetes (T2DM) on measures of glucose homeostasis and markers of oxidative stress. Twenty subjects (10 patients with T2DM and 10 obese subjects) were recruited for the study, and randomized in a double-blinded placebo-controlled manner to consume either 1000 mg GSH per day or placebo for 3 weeks. Before and after the 3 weeks insulin sensitivity was measured with the hyperinsulinemic-euglycemic clamp and a muscle biopsy was obtained to measure GSH and skeletal muscle mitochondrial hydrogen peroxide (H2O2) emission rate. Whole body insulin sensitivity increased significantly in the GSH group. Skeletal muscle GSH was numerically increased (∼19%) in the GSH group; no change was seen in GSH to glutathione disulfide ratio. Skeletal muscle mitochondrial H2O2 emission rate did not change in response to the intervention and neither did the urinary excretion of the RNA oxidation product 8-oxo-7,8-dihydroguanosine or the DNA oxidation product 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), although 8-oxodG decreased as a main effect of time. Oral GSH supplementation improves insulin sensitivity in obese subjects with and without T2DM, although it does not alter markers of oxidative stress. The study has been registered in clinicaltrials.gov (NCT02948673). Novelty: Reduced glutathione supplementation increases insulin sensitivity in obese subjects with and without T2DM. H2O2 emission rate from skeletal muscle mitochondria was not affected by GSH supplementation.

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

Background Whole-body oxidative stress can be estimated by the urine excretion of oxidized guanosine species, 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG), derived from RNA and DNA, respectively. These oxidative stress markers are not well explored in thyroid disorders. Objective We aimed to determine whether treatment of hyperthyroid patients affects the levels of these oxidative stress markers. Methods Urinary excretion of 8-oxoGuo and 8-oxodG was measured in 51 hyperthyroid patients (toxic nodular goiter [TNG], n = 30; Graves disease [GD], n = 21) before or shortly after initiation of therapy and when stable euthyroidism had been achieved for at least 12 months. Results Adjusting for age, the baseline urinary excretion of oxidative stress markers correlated positively with plasma thyroxine (8-oxoGuo, P = 0.002; 8-oxodG, P = 0.021) and was significantly higher in GD than in TNG patients (P = 0.001 for both oxidative stress markers). Restoration of euthyroidism significantly affected the excretion of the oxidative stress markers. In TNG, 8-oxoGuo decreased from geometric mean 2.11 nmol/mmol creatinine (95% CI, 1.85-2.39) to 1.91 nmol/mmol (95% CI, 1.67-2.19; P = 0.001), while 8-oxodG decreased from 1.65 nmol/mmol (95% CI, 1.41-1.93) to 1.48 nmol/mmol (95% CI, 1.27-1.74; P = 0.026). In GD, 8-oxoGuo decreased from 2.25 nmol/mmol (95% CI, 1.95-2.59) to 1.79 nmol/mmol (95% CI, 1.63-1.97; P = 0.0003), while 8-oxodG decreased from 2.02 nmol/mmol (95% CI, 1.73-2.38) to 1.54 nmol/mmol (95% CI, 1.31-1.81; P = 0.001). In the euthyroid state, there were no differences between groups. Conclusion Restoration of euthyroidism in patients with hyperthyroidism significantly decreased the systemic oxidative stress load by 10% to 25%. Our findings may help to explain the higher morbidity and mortality linked to hyperthyroid diseases, as shown in observational studies.

Growing evidence supports that pharmacological application of growth differentiation factor 15 (GDF15) suppresses appetite but also promotes sickness-like behaviors in rodents via GDNF family receptor α-like (GFRAL)-dependent mechanisms. Conversely, the endogenous regulation of GDF15 and its physiological effects on energy homeostasis and behavior remain elusive. Here we show, in four independent human studies that prolonged endurance exercise increases circulating GDF15 to levels otherwise only observed in pathophysiological conditions. This exercise-induced increase can be recapitulated in mice and is accompanied by increased Gdf15 expression in the liver, skeletal muscle, and heart muscle. However, whereas pharmacological GDF15 inhibits appetite and suppresses voluntary running activity via GFRAL, the physiological induction of GDF15 by exercise does not. In summary, exercise-induced circulating GDF15 correlates with the duration of endurance exercise. Yet, higher GDF15 levels after exercise are not sufficient to evoke canonical pharmacological GDF15 effects on appetite or responsible for diminishing exercise motivation., The physiological role of GDF15 remains poorly defined. Here, the authors show that circulating GDF15 increases in response to prolonged exercise, but that this exercise-induced GDF15, unlike pharmacological GDF15, does not affect post-exercise food intake or exercise motivation.

Surgical stress is followed by oxidative stress, where reactive oxygene species may act as regulators of pathways related to cancer cell survival and metastatic ability. Furthermore, reactive oxygene species may cause DNA and RNA damage. The aim of this study was to examine whether laparoscopic colon cancer surgery causes oxidative stress and dysregulation of related pathways. Methods: Patients undergoing elective laparoscopic surgery for colon cancer were included. Blood and urine samples were drawn on the day prior to surgery and on day 1 and 10 after surgery. Results: Twenty-six patients were included. Out of 140 genes previously identified as sensitive to regulation by reactive oxygene species, 46 were significantly differentially expressed on day 1 after surgery (FDR < 0.05). Upregulated genes were related to cellular immune suppression, proliferation, migration and epithelial to mesenchymal transition. Downregulated genes were related to IFN pathways and cytotoxic immunological reactions. Genes related to DNA repair were primarily downregulated on day one after surgery, and urinary excretion of 8oxdG was decreased on day two after (p = 0.004), and increased on day 10 after surgery (p = 0.01). Conclusion: Laparoscopic colon cancer surgery causes oxidative stress, and impaired DNA repair. Gene expression profiling indicates that reactive oxygen species may act as regulators of pathways related to increased risk of metastasis and cellular immune suppression after surgery. Measures of intracellular oxidative stress, indicates impaired DNA repair on day two after surgery, and sustained oxidative stress on day 10 after surgery.

Aims: To investigate the effect of adding the short-acting glucagon-like peptide 1 receptor agonist (GLP-1RA) exenatide to insulin treatment on markers of cardiovascular risk in type 1 diabetes. Materials and methods: In a randomized, double-blind, parallel-group trial, 108 individuals with type 1 diabetes aged ≥18 years on multiple daily injection therapy with a body mass index >22.0 kg/m2 and glycated haemoglobin concentration of 59 to 88 mmol/mol (7.5%−10.0%) were randomized (1:1) to preprandial subcutaneous injection of 10 μg exenatide (Byetta®) or placebo three times daily over 26 weeks as add-on treatment to existing insulin therapy. Reported markers of cardiovascular risk were secondary endpoints and were analyzed in a baseline-adjusted linear mixed model in the intention-to-treat population. The primary results of this study, the MAG1C (Meal-time Administration of exenatide for Glycaemic control in type 1 diabetes Cases) trial, were previously reported. Results: Exenatide changed total fat mass by −2.6 kg (95% confidence interval [CI] −3.6; −1.6; P < 0.0001) and lean body mass by −1.1 kg (95% CI −1.9; −0.4; P = 0.01) compared with placebo, as assessed by dual-energy X-ray absorptiometry. Fat mass reductions were similar for central and peripheral fat mass. Exenatide did not change levels of interleukin-2 or -6; tumour necrosis factor-α; C-reactive protein; N-terminal prohormone of brain natriuretic peptide; or 8-oxo-7,8-dihydroguanosine (RNA oxidation marker) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (DNA oxidation marker). Conclusions: Exenatide added to insulin therapy in type 1 diabetes for 26 weeks resulted in body weight loss primarily from fat mass reduction, but had no effect on biomarkers of cardiovascular disease risk.

Acute and adaptive changes in systemic markers of oxidatively generated nucleic acid modifications (i.e., 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo)) as well as inflammatory cytokines (i.e., C-reactive protein, interleukin-6, interleukin-10, and tumour necrosis factor alpha), a liver hormone (i.e., fibroblast growth factor 21 (FGF21)), and bone metabolism markers (sclerostin, osteocalcin, C-terminal telopeptide, and N-terminal propeptide of type 1 procollagen) were investigated following a marathon in 20 study participants. Immediate changes were observed in inflammatory cytokines, FGF21, and bone metabolism markers following the marathon. In contrast, no immediate changes in urinary excretion of 8-oxodG and 8-oxoGuo were evident. Four days after the marathon, decreased urinary excretion of 8-oxodG (-2.9 (95% CI -4.8;-1.1) nmol/24 h,8-oxodG: 8-oxo-7,8-dihydro-2'-deoxyguanosine; 8-oxoGuo: 8-oxo-7,8-dihydroguanosine; CI: confidence interval; CTX: C-terminal telopeptide of type 1 collagen; DXA: dual-energy X-ray absorptiometry; ELISA: enzyme-linked immunosorbent assay; FGF21: Fibroblast growth factor 21; h: hour; hsCRP: high sensitivity C-reactive protein; IL: interleukin; IQR: interquartile range; MS: mass spectrometry: P1NP: N-terminal propeptide of type 1 procollagen; TNFα: tumour necrosis factor alpha; UPLC: ultra-performance liquid chromatography.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) improve hard renal outcomes in type 2 diabetes. This is possibly explained by the fact that SGLT2i normalize the measured glomerular filtration rate (mGFR) by increasing renal vascular resistance, as was shown in young people with type 1 diabetes and glomerular hyperfiltration. Therefore, we compared the renal hemodynamic effects of dapagliflozin with gliclazide in type 2 diabetes. The mGFR and effective renal plasma flow were assessed using inulin and para-aminohippurate clearances in the fasted state, during clamped euglycemia (5 mmol/L) and during clamped hyperglycemia (15 mmol/L). Filtration fraction and renal vascular resistance were calculated. Additionally, factors known to modulate renal hemodynamics were measured. In 44 people with type 2 diabetes on metformin monotherapy (Hemoglobin A1c 7.4%, mGFR 113 mL/min), dapagliflozin versus gliclazide reduced mGFR by 5, 10, and 12 mL/min in the consecutive phases while both agents similarly improved Hemoglobin A1c (-0.48% vs -0.65%). Dapagliflozin also reduced filtration fraction without increasing renal vascular resistance, and increased urinary adenosine and prostaglandin concentrations. Gliclazide did not consistently alter renal hemodynamic parameters. Thus, beyond glucose control, SGLT2i reduce mGFR and filtration fraction in type 2 diabetes. The fact that renal vascular resistance was not increased by dapagliflozin suggests that this is due to post-glomerular vasodilation rather than pre-glomerular vasoconstriction.

To evaluate the association of urinary oxidized guanine/guanosine (OxGuo) levels with incident type 2 diabetes (T2D) among older adults.A nested case-control design was applied with 440 cases of incident T2D and 440 controls, randomly sampled from all 65-75 year-old study participants of the ESTHER study, which is a population-based German cohort study with 14 years of follow-up. Analyses of 8-hydroxy-2'-deoxyguanosine (8-oxo-dGuo; DNA oxidation product) and 8-hydroxyguanosine (8-oxo-Guo; RNA oxidation product) were measured by ultra-performance liquid chromatography tandem-mass spectrometry (UPLC-MS/MS). The sum of the two OxGuo molecule concentrations was calculated and called OxGuo-UPLC-MS/MS. The corresponding OxGuo-ELISA levels were measured by Cayman's DNA/RNA oxidative damage ELISA, which detects a mix of 8-oxo-dGuo, 8-oxo-Guo and one other OxGuo molecule. Logistic regression was applied and models were adjusted for age, sex, BMI, HbA8-oxo-dGuo and 8-oxo-Guo were highly correlated with each other (r = 0.642) and weakly correlated with OxGuo-ELISA (r = 0.22 and r = 0.14, respectively). OxGuo-ELISA levels were statistically significant associated with T2D incidence (odds ratio (OR) and 95% confidence interval [95%CI] for comparison of top and bottom quartile: 1.77 [1.14; 2.76]). In contrast, the ORs did not increase stepwise from quartile 2 to 4 for neither 8-oxo-Guo, 8-oxo-dGuo levels nor OxGuo-UPLC-MS/MS and comparisons of top and bottom quartile were not statistically significant. In a post-hoc analysis comparing bottom quartile 1 with a combined group of quartile 2-4, the association of OxGuo-UPLC-MS/MS with T2D incidence reached statistical significance (OR [95%CI]: 0.66 [0.46; 0.96]) and was very similar with the one obtained for OxGuo-ELISA (OR [95%CI]: 0.66 [0.45; 0.95]).Although only the measurements of the DNA/RNA oxidative damage ELISA kit of Cayman were statistically significantly associated with T2D incidence in the main analysis, confidence intervals overlapped and the post-hoc analysis showed that results for OxGuo-UPLC-MS/MS were quite comparable.

Metformin and exercise both improve glycemic control, but in vitro studies have indicated that an interaction between metformin and exercise occurs in skeletal muscle, suggesting a blunting effect of metformin on exercise training adaptations. Two studies (a double-blind, parallel-group, randomized clinical trial conducted in 29 glucose-intolerant individuals and a double-blind, cross-over trial conducted in 15 healthy lean males) were included in this paper. In both studies, the effect of acute exercise ± metformin treatment on different skeletal muscle variables, previously suggested to be involved in a pharmaco-physiological interaction between metformin and exercise, was assessed. Furthermore, in the parallel-group trial, the effect of 12 weeks of exercise training was assessed. Skeletal muscle biopsies were obtained before and after acute exercise and 12 weeks of exercise training, and mitochondrial respiration, oxidative stress and AMPK activation was determined. Metformin did not significantly affect the effects of acute exercise or exercise training on mitochondrial respiration, oxidative stress or AMPK activation, indicating that the response to acute exercise and exercise training adaptations in skeletal muscle is not affected by metformin treatment. Further studies are needed to investigate whether an interaction between metformin and exercise is present in other tissues, e.g., the gut. Trial registration: ClinicalTrials.gov (NCT03316690 and NCT02951260). Novelty: Metformin does not affect exercise-induced alterations in mitochondrial respiratory capacity in human skeletal muscle. Metformin does not affect exercise-induced alterations in systemic levels of oxidative stress nor emission of reactive oxygen species from human skeletal muscle. Metformin does not affect exercise-induced AMPK activation in human skeletal muscle.

The myeloproliferative neoplasms are associated with chronic kidney disease but whether clonal haematopoiesis of indeterminate potential (CHIP) is associated with impaired kidney function is unknown. In the Danish General Suburban Population Study (N = 19 958) from 2010 to 2013, 645 individuals were positive for JAK2V617F (N = 613) or CALR (N = 32) mutations. Mutation-positive individuals without haematological malignancy were defined as having CHIP (N = 629). We used multiple and inverse probability weighted (IPW)-adjusted linear regression analysis to estimate adjusted mean (95% confidence interval) differences in estimated glomerular filtration rate (eGFR; ml/min/1.73 m2) by mutation status, variant allele frequency (VAF%), blood cell counts, and neutrophil-to-lymphocyte ratio (NLR). We performed 11-year longitudinal follow-up of eGFR in all individuals. Compared to CHIP-negative individuals, the mean differences in eGFR were −5.6 (−10.3, −0.8, p =.02) for CALR, −11.9 (−21.4, −2.4, p = 0.01) for CALR type 2, and −10.1 (−18.1, −2.2, p =.01) for CALR with VAF ≥ 1%. The IPW-adjusted linear regression analyses showed similar results. NLR was negatively associated with eGFR. Individuals with CALR type 2 had a worse 11-year longitudinal follow-up on eGFR compared to CHIP-negative individuals (p =.004). In conclusion, individuals with CALR mutations, especially CALR type 2, had impaired kidney function compared to CHIP-negative individuals as measured by a lower eGFR at baseline and during 11-year follow-up.

Previous studies have indicated that antidepressants that inhibit the serotonin transporter reduces oxidative stress. DNA and RNA damage from oxidation is involved in aging and a range of age-related pathophysiological processes. Here, we studied the urinary excretion of markers of DNA and RNA damage from oxidation, 8-oxodG and 8-oxoGuo, respectively, in the NeuroPharm cohort of 100 drug-free patients with unipolar depression and in 856 non-psychiatric community controls. Patients were subsequently treated for 8 weeks with escitalopram in flexible doses of 5–20 mg; seven of these switched to duloxetine by week 4, as allowed by the protocol. At week 8, 82 patients were followed up clinically and with measurements of 8-oxodG/8-oxoGuo. Contextual data were collected in patients, including markers of cortisol excretion and low-grade inflammation. The intervention was associated with a substantial reduction in both 8-oxodG/8-oxoGuo excretion (25% and 10%, respectively). The change was not significantly correlated to measures of clinical improvement. Both markers were strongly and negatively correlated to cortisol, as measured by the area under the curve for the full-day salivary cortisol excretion. Surprisingly, patients had similar levels of 8-oxodG excretion and lower levels of 8-oxoGuo excretion at baseline compared to the controls. We conclude that intervention with serotonin reuptake inhibitors in unipolar depression is associated with a reduction in systemic DNA and RNA damage from oxidation. To our knowledge, this to date the largest intervention study to characterize this phenomenon, and the first to include a marker of RNA oxidation.

Objective:Oxidative stress has been suggested to increase after electroconvulsive therapy (ECT), a treatment which continues to be the most effective for severe depression. Oxidative stress could potentially be mechanistically involved in both the therapeutic effects and side effects of ECT.Methods:We measured sensitive markers of systemic and central nervous system (CNS) oxidative stress on DNA and RNA (urinary 8-oxodG/8-oxoGuo, cerebrospinal fluid 8-oxoGuo, and brain oxoguanine glycosylase mRNA expression) in male rats subjected to electroconvulsive stimulations (ECS), an animal model of ECT. Due to the previous observations that link hypothalamic–pituitary–adrenal (HPA)-axis activity and age to DNA/RNA damage from oxidation, groups of young and middle-aged male animals were included, and markers of HPA-axis activity were measured.Results:ECS induced weight loss, increased corticosterone (only in middle-aged animals), and decreased cerebral glucocorticoid receptor mRNA expression, while largely leaving the markers of systemic and CNS DNA/RNA damage from oxidation unaltered.Conclusion:These results suggest that ECS is not associated with any lasting effects on oxidative stress on nucleic acids neither in young nor middle-aged rats.

BackgroundMetabolic syndrome (MetS) is associated with reduced life expectancy in patients with affective disorders, however, whether MetS also plays a role before the onset of affective disorder is unknown. We aimed to investigate whether MetS, inflammatory markers or oxidative stress act as risk factors for affective disorders, and whether MetS is associated with increased inflammation and oxidative stress.MethodsWe conducted a high-risk study including 204 monozygotic (MZ) twins with unipolar or bipolar disorder in remission or partial remission (affected), their unaffected co-twins (high-risk) and twins with no personal or family history of affective disorder (low-risk). Metabolic Syndrome was ascertained according to the International Diabetes Federation (IDF) criteria. Inflammatory markers and markers of oxidative stress were analyzed from fasting blood and urine samples, respectively.ResultsThe affected and the high-risk group had a significantly higher prevalence of MetS compared to the low-risk group (20%v.15%v.2.5%,p= 0.0006), even after adjusting for sex, age, smoking and alcohol consumption. No differences in inflammatory and oxidative markers were seen between the three groups. Further, MetS was associated with alterations in inflammatory markers, and oxidative stress was modestly correlated with inflammation.ConclusionMetabolic syndrome is associated with low-grade inflammation and may act as a risk factor and a trait marker for affective disorders. If confirmed in longitudinal studies, this suggests the importance of early intervention and preventive approaches targeted towards unhealthy lifestyle factors that may contribute to later psychopathology.

Isoguanine (2-hydroxyadenine), considered to be a non-natural nucleobase has, however, been shown to occur in the croton bean, butterfly wings and a mollusk. For the first time, to the best of our knowledge, we report the identification of isoguanosine (2-hydroxyadenosine), the ribonucleoside, in humans and mouse. Isoguanosine is identified and quantified in RNA from mouse liver samples and in human urine and cerebrospinal fluid. Isoguanine could not be detected as the 2'-deoxyribonucleoside in mouse liver DNA. It could be speculated that the source of isoguanosine was formation from adenosine during oxidative stress in the body. However, the urinary concentrations of isoguanosine and the levels in the liver found here by using isotope dilution liquid chromatography-tandem mass spectrometry are identical to or exceed those of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydro-guanosine. Guanine is the nucleobase that is oxidized the easiest, so it appears spectacular that the levels of isoguanosine are higher than the levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydro-guanosine. It also appears intriguing that it was only possible to detect the ribonucleoside isoguanosine and not the 2'-deoxyribonucleoside. These observations could indicate that the isoguanosine found is not formed by oxidative stress and could have biological functions.

Major depressive disorder (MDD) affects 350 million people worldwide and is a serious socio-economic burden. The most efficient treatment of MDD is electroconvulsive therapy (ECT), which has been shown to influence the oxidative status believed to be part of the pathophysiology of MDD. We investigated the effects of chronic electroconvulsive stimulation (ECS) on mitochondrial respiration and mitochondrial hydrogen peroxide production, RNA oxidation, and the content of mitochondria in the piriform cortex of the rat. We found reductions of mitochondrial respiration in respiratory states 2 and 3 by 33% and 32%, respectively, and a 23% reduction in electron transfer capacity. RNA oxidation, as measured by 8-oxo-7,8-dihydroguanosine, was increased by 58%, while mitochondrial production of H2O2 was unaffected. The increased oxidative stress may thus be ascribed to extra-mitochondrial sources.

In a double-blinded, randomized, crossover trial, we investigated the hemodynamic effects of high-dose intravenous lipid emulsion (ILE) with/without metoprolol. Ten healthy volunteers each completed 4 trial days (placebo + ILE; metoprolol + placebo; metoprolol + ILE; placebo + placebo) in random order. Metoprolol was administered as an initial bolus (10 mg), followed by an infusion (50 mg) from 5 to 30 minutes. ILE was administered as a bolus at 12.5 minutes (2.5 mL/kg), followed by a 15-minute infusion (0.25 mL/kg per minute). On metoprolol + ILE days (compared with metoprolol + placebo) after 120 minutes, mean heart rates were significantly higher (difference, 5.5 beats per minute (bpm); 95% confidence interval (CI), 3.0-8.1 bpm; P < 0.001), and average relative cardiac output was higher (difference, 10 percentage points; 95% CI, 5-15 percentage points; P < 0.001). The hemodynamic effect of ILE developed gradually. ILE had no effect on plasma metoprolol or major adverse events. In conclusion, high-dose ILE has relatively marginal and delayed hemodynamic effects that may have limited clinical relevance in the short-term clinical toxicological setting.

Glucagon-like peptide 1 receptor agonists have shown cardioprotective effects which have been suggested to be mediated through inhibition of oxidative stress. We investigated the effect of treatment with a glucagon-like peptide 1 receptor agonist (liraglutide) on oxidative stress measured as urinary nucleic acid oxidation in persons with type 2 diabetes. Post-hoc analysis of two independent, randomised, placebo-controlled and double-blinded clinical trials. In a cross-over study where persons with type 2 diabetes and microalbuminuria (LIRALBU, n = 32) received liraglutide (1.8 mg/day) or placebo for 12 weeks in random order, separated by 4 weeks of wash-out. In a parallel-grouped study where obese persons with type 2 diabetes (SAFEGUARD, n = 56) received liraglutide (1.8 mg/day), sitagliptin (100 mg/day) or placebo for 12 weeks. Endpoints were changes in the urinary markers of DNA oxidation (8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG)) and RNA oxidation [8-oxo-7,8-dihydroguanosine (8-oxoGuo)]. In LIRALBU, we observed no significant differences between treatment periods in urinary excretion of 8-oxodG [0.028 (standard error (SE): 0.17] nmol/mmol creatinine, p = 0.87) or of 8-oxoGuo [0.12 (0.12) nmol/mmol creatinine, p = 0.31]. In SAFEGUARD, excretion of 8-oxodG was not changed in the liraglutide group [2.8 (− 8.51; 15.49) %, p = 0.62] but a significant decline was demonstrated in the placebo group [12.6 (− 21.3; 3.1) %, p = 0.02], resulting in a relative increase in the liraglutide group compared to placebo (0.16 nmol/mmol creatinine, SE 0.07, p = 0.02). Treatment with sitagliptin compared to placebo demonstrated no significant difference (0.07 (0.07) nmol/mmol creatinine, p = 0.34). Nor were any significant differences for urinary excretion of 8-oxoGuo liraglutide vs placebo [0.09 (SE: 0.07) nmol/mmol creatinine, p = 0.19] or sitagliptin vs placebo [0.07 (SE: 0.07) nmol/mmol creatinine, p = 0.35] observed. This post-hoc analysis could not demonstrate a beneficial effect of 12 weeks of treatment with liraglutide or sitagliptin on oxidatively generated modifications of nucleic acid in persons with type 2 diabetes.

Background Lifestyle intervention, i.e. diet and physical activity, forms the basis for care of type 2 diabetes (T2D). The current physical activity recommendation for T2D is aerobic training for 150 min/week of moderate to vigorous intensity, supplemented with resistance training 2–3 days/week, with no more than two consecutive days without physical activity. The rationale for the recommendations is based on studies showing a reduction in glycated haemoglobin (HbA1c). This reduction is supposed to be caused by increased insulin sensitivity in muscle and adipose tissue, whereas knowledge about effects on abnormalities in the liver and pancreas are scarce, with the majority of evidence stemming from in vitro and animal studies. The aim of this study is to investigate the role of the volume of exercise training as an adjunct to dietary therapy in order to improve the pancreatic β-cell function in T2D patients less than 7 years from diagnosis. The objective of this protocol for the DOSE-EX trial is to describe the scientific rationale in detail and to provide explicit information about study procedures and planned analyses. Methods/design In a parallel-group, 4-arm assessor-blinded randomised clinical trial, 80 patients with T2D will be randomly allocated (1:1:1:1, stratified by sex) to 16 weeks in either of the following groups: (1) no intervention (CON), (2) dietary intervention (DCON), (3) dietary intervention and supervised moderate volume exercise (MED), or (4) dietary intervention and supervised high volume exercise (HED). Enrolment was initiated December 15th, 2018, and will continue until N = 80 or December 1st, 2021. Primary outcome is pancreatic beta-cell function assessed as change in late-phase disposition index (DI) from baseline to follow-up assessed by hyperglycaemic clamp. Secondary outcomes include measures of cardiometabolic risk factors and the effect on subsequent complications related to T2D. The study was approved by The Scientific Ethical Committee at the Capital Region of Denmark (H-18038298). Trial registration: The Effects of Different Doses of Exercise on Pancreatic β-cell Function in Patients With Newly Diagnosed Type 2 Diabetes (DOSE-EX), NCT03769883, registered 10 December 2018 https://clinicaltrials.gov/ct2/show/NCT03769883). Any modification to the protocol, study design, and changes in written participant information will be approved by The Scientific Ethical Committee at the Capital Region of Denmark before effectuation. Discussion The data from this study will add knowledge to which volume of exercise training in combination with a dietary intervention is needed to improve β-cell function in T2D. Secondarily, our results will elucidate mechanisms of physical activity mitigating the development of micro- and macrovascular complications correlated with T2D.

Patients with neurodegenerative disorders, schizophrenia, and bipolar disorder present with increased oxidative stress markers. Not only is oxidative stress associated with development of disease, but also with increased disease progression and mortality. Oxidative stress reflects an increase in pro-oxidants, which subsequently leads to oxidative modifications of cellular components, such as RNA and DNA. Urinary excretion of 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is the valid marker of whole-body RNA and DNA damage, respectively. Recently, cerebrospinal fluid (CSF) oxidative stress markers of RNA damage (8-oxoGuo) have showed both state and trait dependence in patients with bipolar disorder. However, the relation to subjective measures of stress and quality of life (QoL) is unknown.This prospective, longitudinal 1-year follow-up case-control study investigated the association between the oxidative stress markers, 8-oxoGuo and 8-oxodG and, perceived stress and QoL in patients with bipolar disorder (We found that markers of oxidative stress in CSF and urine were not associated with perceived stress and QoL quality in patients with bipolar disorder. However, a putative association between urinary 8-oxoGuo oxidative stress marker for RNA damage and perceived stress in HC encourages further investigations.

Prior studies in bipolar disorders (BD) have suggested that oxidative stress and cellular ageing play a key role in the pathophysiology of BD. Nevertheless, oxidative stress has not been investigated in patients with newly diagnosed BD and in their unaffected first-degree relatives (UR), compared with healthy control individuals (HC).We investigated the level of systemic oxidative damage to DNA and RNA measured by urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) levels, respectively, in 360 patients with newly diagnosed BD, 92 of their UR and 197 HC.Independent of lifestyle and demographic variables, levels of both 8-oxoGuo and 8-oxodG was 17.1% (B = 1.171, 95%CI = 1.125-1.219, p 0.001) and 21.2% (B = 1.212, 95%CI = 1.145-1.283, p 0.001) higher, respectively, in patients with BD compared with HC and 13.3% (B = 1.133, 95%CI = 1.069-1.200, p 0.001) and 26.6% (B = 1.266, 95%CI = 1.167-1.374, p 0.001) higher, respectively, in UR compared with HC. Neither 8-oxoGuo nor 8-oxodG levels differed between patients with BD and UR. These findings were replicated in patients in full or partial remission and were consistent both in BD type I and II.Overall, the findings of higher oxidative stress in patients with newly diagnosed BD and their UR suggest that systemic nucleoside damage by oxidative stress is present prior to onset and in the early stages of BD thereby potentially representing trait markers of BD.

Biotin (or Vitamin B7) is a vitamin where deficiency can be caused by inadequate intake. Biotin deficiency is rare, as most people get enough biotin from diet, since many foods contain biotin. In addition to biotin from food, intestinal bacteria can synthesize biotin, which can then be absorbed by the body. Supplementation with biotin has been advocated, mainly due to proposed beneficial effects on skin, nail and hair growth. There is no evidence that high biotin intakes are toxic, but a high intake may interfere with diagnostic assays that use biotin-streptavidin technology. These tests are commonly used to measure plasma concentrations of a wide range of hormones. Erroneous results may lead to misdiagnosis of various endocrine disorders. Supplementation with high-dose biotin has been used experimental for the treatment of diseases (e.g. multiple sclerosis) and high doses are used to obtain effect on nail and hair growth. On this background a demand for tests to determine if there is a risk of obtaining false test results when using biotin-streptavidin based tests have appeared. In this paper we present a method based on column switching liquid chromatography tandem mass spectrometry for the quantification of biotin in plasma and serum and explore the effects of biotin on an immunoassay based on biotin strept(avidin) chemistry.

It is unknown if the somatic mutations in chronic myeloproliferative neoplasms (MPNs), JAK2V617F and Calreticulin, are associated with oxidative stress, or impaired mitochondrial defense against reactive oxygen species. In the Danish General Suburban Population Study (GESUS), including 116 JAK2V617F-mutated, 8 CALR-mutated, and 3310 mutation-negative participants without overt MPN, and in a study of 39 patients with myelofibrosis, the most advances type of MPNs, and 179 matched controls, we compared the urinary concentration of oxidized nucleosides – 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) – as markers of oxidative stress. In GESUS, we performed Mendelian randomization analyses, using the Ala16Val single nucleotide polymorphism in the superoxide dismutase2 (SOD2) gene. In the multivariate analyses in GESUS, the 8-oxodG and 8-oxoGuo concentration were 13% (95%CI: 6–21%, p < 0.001) and 6% (95%CI: 0.4–11%, p = 0.035) higher in mutation-positive than in mutation-negative participants, respectively. Each SOD2 T allele was associated with an odds ratio of being mutation-positive of 1.69 (95%CI: 1.12–2.55, p = 0.013) through 8-oxodG. The 8-oxodG and 8-oxoGuo concentrations were 77% (95%CI: 49–110%, p < 0.001) and 105% (95%CI: 80–133%, p < 0.001) higher in myelofibrosis patients than in controls, respectively. In conclusion, an impaired mitochondrial antioxidative defense, that is causatively associated with markers of oxidative stress, may contribute to the development of mutations associated with MPNs.

Aims Insulin resistance associates with development of metabolic syndrome and risk of cardiovascular disease. The link between insulin resistance and cardiovascular disease is complex and multifactorial. Confirming the genetic link between insulin resistance, type 2 diabetes, and coronary artery disease, as well as the extent of coronary artery disease, is important and may provide better risk stratification for patients at risk. We investigated whether a genetic risk score of 53 single nucleotide polymorphisms known to be associated with insulin resistance phenotypes was associated with diabetes and burden of coronary artery disease. Methods and results We genotyped patients with a coronary angiography performed in the capital region of Denmark from 2010–2014 and constructed a genetic risk score of the 53 single nucleotide polymorphisms. Logistic regression using quartiles of the genetic risk score was performed to determine associations with diabetes and coronary artery disease. Associations with the extent of coronary artery disease, defined as one-, two- or three-vessel coronary artery disease, was determined by multinomial logistic regression. We identified 4,963 patients, of which 17% had diabetes and 55% had significant coronary artery disease. Of the latter, 27%, 14% and 14% had one, two or three-vessel coronary artery disease, respectively. No significant increased risk of diabetes was identified comparing the highest genetic risk score quartile with the lowest. An increased risk of coronary artery disease was found for patients with the highest genetic risk score quartile in both unadjusted and adjusted analyses, OR 1.21 (95% CI: 1.03, 1.42, p = 0.02) and 1.25 (95% CI 1.06, 1.48, p Conclusions Among patients referred for coronary angiography, only a strong genetic predisposition to insulin resistance was associated with risk of coronary artery disease and with a greater disease burden.

In type 2 diabetes, some glucagon-like peptide 1 receptor agonists (GLP-1RAs) reduce the risk of major adverse cardiovascular events. Whether GLP-1RAs have any effect on cardiovascular disease risk in patients with type 1 diabetes remains to be elucidated. We tested the effect of adding the short-acting GLP-1RA exenatide to insulin treatment on markers of cardiovascular risk in type 1 diabetes. In a randomized, double-blinded, parallel-group trial, 108 individuals with type 1 diabetes aged ≥18 years on multiple daily insulin injection therapy with body mass index >22.0 kg/m2 and HbA1c 7.5-10.0% (59-88 mmol/mol) were randomized (1:1) to preprandial subcutaneous injection of 10 µg exenatide (Byetta®) or placebo three times daily over 26 weeks as add-on treatment to existing insulin therapy. Reported data were secondary endpoints and analyzed in a baseline-adjusted linear mixed model in the intention-to-treat population. Exenatide changed total fat mass by -2.6 kg (95% CI -3.6;-1.6, P Exenatide added to insulin therapy in type 1 diabetes for 26 weeks resulted in body weight loss primarily from fat mass reduction but had no effect on circulating biomarkers of cardiovascular disease risk. Disclosure N.J. Johansen: Research Support; Self; AstraZeneca. T.F. Dejgaard: Advisory Panel; Self; Novo Nordisk A/S. Consultant; Self; Boehringer Ingelheim International GmbH, Novo Nordisk A/S. Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Novo Nordisk A/S. A. Lund: Speaker’s Bureau; Self; AstraZeneca, Novo Nordisk A/S, Sanofi. C. Schlüntz: None. E. Larsen: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc. H.E. Poulsen: Research Support; Self; Boehringer Ingelheim International GmbH. J.P. Gøtze: None. H. Møller: None. T. Vilsbøll: Advisory Panel; Self; AstraZeneca, Mundipharma International, Novo Nordisk A/S, Sun Pharmaceutical Industries Ltd. Consultant; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Lilly Diabetes, Medscape, Merck Sharp & Dohme Corp., Sanofi. H.U. Andersen: Advisory Panel; Self; Novo Nordisk A/S. Stock/Shareholder; Self; Novo Nordisk A/S. F.K. Knop: Advisory Panel; Self; AstraZeneca, Merck Sharp & Dohme Corp., Mundipharma International, Novo Nordisk A/S, Sanofi. Consultant; Self; Carmot Therapeutics, Inc., Eli Lilly and Company, Novo Nordisk A/S. Research Support; Self; AstraZeneca, Gubra, Novo Nordisk A/S, Sanofi, Zealand Pharma A/S. Speaker’s Bureau; Self; AstraZeneca, Lupin Pharmaceuticals, Inc., Merck Sharp & Dohme Corp., Norgine B.V., Novo Nordisk A/S. Funding AstraZeneca

Purpose: Oxidative stress may play an important role in childhood obesity and increased cardiometabolic risk. 8-oxo-7,8-dihydroguanosine (8-oxoGuo) from oxidation of RNA and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) from oxidation of DNA are excreted into urine and function as biomarkers for oxidative stress reflecting the modification rate of nucleic acids by oxidation. This study investigates the associations between urinary markers of nucleic acid oxidation and Body Mass Index (BMI), age, sex and cardiometabolic risk factors in children and adolescents with and without obesity. Methods: We studied 543 children and adolescents from an obesity clinic cohort (n = 418) and a population-based cohort (n = 125), all aged 6–18 years. Anthropometrics, urine and blood samples were collected. A validated liquid chromatography-tandem mass spectrometry method was used to measure the nucleic acid oxidation markers. Results: Compared with the population-based cohort, children and adolescents in the obesity clinic cohort had higher calculated 24-h excretion of 8-oxoGuo (p = 0.045) and 8-oxodG (p = 0.014) adjusted for basal metabolic rate. Both oxidation markers were positively associated with age and female sex (all p < 0.002). In the obesity clinic cohort the RNA oxidation marker 8-oxoGuo correlated with serum insulin (rho = 0.18, p =

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

Carbohydrate-restricted diets are increasingly recognized as options for dietary management of type 2 diabetes mellitus (T2DM). We investigated the effects of a carbohydrate-reduced high-protein (CRHP) and a conventional diabetes (CD) diet on oxidative stress and inflammation in weight stable individuals with T2DM. We hypothesized that the CRHP diet would improve markers of oxidatively generated RNA and DNA modifications as well as inflammatory parameters. Thirty participants with T2DM were randomized to 6 weeks of CRHP or CD dietary treatment (30/50 energy percentage (E%) carbohydrate, 30/17E% protein, 40/33E% fat), followed by a cross-over to the opposite diet for a subsequent 6-week period. All meals were provided during the study and body weight was controlled. Diurnal urine samples were collected after 4 weeks on each diet and oxidatively generated RNA and DNA modifications were measured as 8-oxo-7,8-dihydroguanosine (8-oxoGuo) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), respectively. Fasting concentrations of soluble urokinase plasminogen activator receptor, high-sensitivity C-reactive protein, tumor necrosis factor alpha and interleukin-6 were measured before and after 6 weeks of interventions. Compared with the CD diet, the CRHP diet increased 24-hour urinary excretion of 8-oxoGuo by 9.3% (38.6 ± 12.6 vs. 35.3 ± 11.0 nmol/24 h, p = .03), whereas 8-oxodG did not differ between diets (24.0 ± 9.5 vs. 24.8 ± 11.1 nmol/24 h, p = .17). Changes in plasma inflammatory parameters did not differ between CRHP and CD diets, all p ≥ .2. The clinical implications of increased RNA oxidation following a CRHP diet as well as long-term effects of carbohydrate-restriction on markers of oxidatively generated nucleic acid modifications should be a field of future study.