One-year follow-up of clinical, metabolic and oxidative stress profile of morbid obese patients after laparoscopic sleeve gastrectomy. 8-oxo-dG as a clinical marker.

Obesity has grown worldwide over the last few decades. In its different degrees, obesity is accompanied by many clinical and biochemical alterations reflecting the pathological condition of various body tissues. Among the mechanisms underlying the pathogenesis of obesity and associated complications, oxidative stress (OS) may be playing an important role. In the present study, we have characterized at systemic level the degree of OS status in a group of morbid obese patients (BMI>40kg/m2) at basal sate and its modulation during one year after bariatric surgery using the laparoscopic sleeve gastrectomy (LSG) technique. As compared with normal weight subjects matched in age, peripheral blood mononuclear cells (PBMc) of obese patients present a significant reduction of the antioxidant enzyme activities superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) as well as a significant increase of the oxidized/reduced glutathione ratio (GSSG/GSH) in these cells. Lipid peroxidation is significantly increased in the patient group as shown by the increased levels of malondialdehyde (MDA) in PBMc and the amount of F2-Isoprostanes (F2-IsoPs) released in urine. In addition, the DNA damage product 8-oxo-7,8-2'-deoxyguanosine (8-oxo-dG) was also observed to be increased in serum and urine of morbid obese patients as compared with the control group. After LSG, an improvement of their ponderal and metabolic profile was accompanied by a progressive recovery of antioxidant enzyme activities and the decline of oxidative byproducts both in PBMc and biological fluids. The observed changes of urinary 8-oxo-dG levels correlate positively with its serum concentration, the lipid peroxidation products MDA and F2-IsoPs, triglycerides, glucose, insulin, HOMA index and body weight and negatively with the percentage of weight and BMI loss and antioxidant activities. We conclude that the analysis of urinary 8-oxo-dG could be validated as a useful marker for the monitoring of ponderal and metabolic status of morbid obese patients.

Frying oils with high natural or added antioxidants content, which protect against postprandial oxidative stress, also protect against DNA oxidation damage.

PURPOSE: Using sunflower oil as frying oil increases postprandial oxidative stress, which is considered the main endogenous source of DNA oxidative damage. We aimed to test whether the protective effect of virgin olive oil and oil models with added antioxidants against postprandial oxidative stress may also protect against DNA oxidative damage. METHODS: Twenty obese people received four breakfasts following a randomized crossover design consisting of different oils [virgin olive oil (VOO), sunflower oil (SFO), and a mixed seed oil (SFO/canola oil) with added dimethylpolysiloxane (SOX) or natural antioxidants from olives (SOP)], which were subjected to 20 heating cycles. RESULTS: We observed the postprandial increase in the mRNA levels of p53, OGG1, POLB, and GADD45b after the intake of the breakfast prepared with SFO and SOX, and an increase in the expression of MDM2, APEX1, and XPC after the intake of the breakfast prepared with SFO, whereas no significant changes at the postprandial state were observed after the intake of the other breakfasts (all p values <0.05). We observed lower 8-OHdG postprandial levels after the intake of the breakfast prepared with VOO and SOP than after the intake of the breakfast prepared with SFO and SOX (all p values <0.05). CONCLUSIONS: Our results support the beneficial effect on DNA oxidation damage of virgin olive oil and the oil models with added antioxidants, as compared to the detrimental use of sunflower oil, which induces p53-dependent DNA repair pathway activation.

Pterostilbene Decreases the Antioxidant Defenses of Aggressive Cancer Cells In Vivo: A Physiological Glucocorticoids- and Nrf2-Dependent Mechanism.

AIMS: Polyphenolic phytochemicals have anticancer properties. However, in mechanistic studies, lack of correlation with the bioavailable concentrations is a critical issue. Some reports had suggested that these molecules downregulate the stress response, which may affect growth and the antioxidant protection of malignant cells. Initially, we studied this potential underlying mechanism using different human melanomas (with genetic backgrounds correlating with most melanomas), growing in nude mice as xenografts, and pterostilbene (Pter, a natural dimethoxylated analog of resveratrol). RESULTS: Intravenous administration of Pter decreased human melanoma growth in vivo. However, Pter, at levels measured within the tumors, did not affect melanoma growth in vitro. Pter inhibited pituitary production of the adrenocorticotropin hormone (ACTH), decreased plasma levels of corticosterone, and thereby downregulated the glucocorticoid receptor- and nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent antioxidant defense system in growing melanomas. Exogenous corticosterone or genetically induced Nrf2 overexpression in melanoma cells prevented the inhibition of tumor growth and decreased antioxidant defenses in these malignant cells. These effects and mechanisms were also found in mice bearing different human pancreatic cancers. Glutathione depletion (selected as an antimelanoma strategy) facilitated the complete elimination by chemotherapy of melanoma cells isolated from mice treated with Pter. INNOVATION: Although bioavailability-related limitations may preclude direct anticancer effects in vivo, natural polyphenols may also interfere with the growth and defense of cancer cells by downregulating the pituitary gland-dependent ACTH synthesis. CONCLUSIONS: Pter downregulates glucocorticoid production, thus decreasing the glucocorticoid receptor and Nrf2-dependent signaling/transcription and the antioxidant protection of melanoma and pancreatic cancer cells. Antioxid. Redox Signal. 24, 974-990.

Oxidative stress and DNA damage in obesity-related tumorigenesis.

Reactive oxygen species induce oxidative modification of critical macromolecules. Oxygen derived free radicals may act as potential cytotoxic intermediates inducing inflammatory and degenerative processes, or as signal messengers for the regulation of gene expression. This dual effect mainly depends on the availability of free radicals in terms of concentration, as well as on the environmental characteristics in which they are produced. The formation of free radicals has been proposed to be the linking factor between certain metabolic disturbances and cancer. Circulating mononuclear cells of patients with high cholesterol levels, insulin resistance, metabolic syndrome or obesity present lower levels of antioxidant enzymes and increased concentrations of oxidative stress by-products such as isoprostanes or the DNA oxidized and highly mutagenic base 8-oxo-7,8-dihydro-2'-deoxyguanosine. Overweight or obese subjects also exhibit hormonal changes as a consequence of the increase of mass fat, and these hormonal alterations have been implicated in the alteration of different signal transduction mechanisms and in cell growth and differentiation. A significant correlation has been found between body mass index and cancer. The biological factors and molecular mechanisms implicated in obesity associated cancer susceptibility will be reviewed.

Oxidative Stress and DNA Damage in Human Gastric Carcinoma: 8-Oxo-7'8-dihydro-2'-deoxyguanosine (8-oxo-dG) as a Possible Tumor Marker.

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

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

AIMS: Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is a widely used biomarker of oxidative stress. However, variability between chromatographic and ELISA methods hampers interpretation of data, and this variability may increase should urine composition differ between individuals, leading to assay interference. Furthermore, optimal urine sampling conditions are not well defined. We performed inter-laboratory comparisons of 8-oxodG measurement between mass spectrometric-, electrochemical- and ELISA-based methods, using common within-technique calibrants to analyze 8-oxodG-spiked phosphate-buffered saline and urine samples. We also investigated human subject- and sample collection-related variables, as potential sources of variability. RESULTS: Chromatographic assays showed high agreement across urines from different subjects, whereas ELISAs showed far more inter-laboratory variation and generally overestimated levels, compared to the chromatographic assays. Excretion rates in timed 'spot' samples showed strong correlations with 24 h excretion (the 'gold' standard) of urinary 8-oxodG (rp 0.67-0.90), although the associations were weaker for 8-oxodG adjusted for creatinine or specific gravity (SG). The within-individual excretion of 8-oxodG varied only moderately between days (CV 17% for 24 h excretion and 20% for first void, creatinine-corrected samples). INNOVATION: This is the first comprehensive study of both human and methodological factors influencing 8-oxodG measurement, providing key information for future studies with this important biomarker. CONCLUSION: ELISA variability is greater than chromatographic assay variability, and cannot determine absolute levels of 8-oxodG. Use of standardized calibrants greatly improves intra-technique agreement and, for the chromatographic assays, importantly allows integration of results for pooled analyses. If 24 h samples are not feasible, creatinine- or SG-adjusted first morning samples are recommended.

The Mediterranean diet improves the systemic lipid and DNA oxidative damage in metabolic syndrome individuals. A randomized, controlled, trial.

BACKGROUND & AIMS: Metabolic syndrome (MetS), in which a non-classic feature is an increase in systemic oxidative biomarkers, presents a high risk of diabetes and cardiovascular disease (CVD). Adherence to the Mediterranean Diet (MedDiet) is associated with a reduced risk of MetS. However, the effect of the MedDiet on biomarkers for oxidative damage has not been assessed in MetS individuals. We have investigated the effect of the MedDiet on systemic oxidative biomarkers in MetS individuals. METHODS: Randomized, controlled, parallel clinical trial in which 110 female with MetS, aged 55-80, were recruited into a large trial (PREDIMED Study) to test the efficacy of the traditional MedDiet on the primary prevention of CVD. Participants were assigned to a low-fat diet or two traditional MedDiets (MedDiet + virgin olive oil or MedDiet + nuts). Both MedDiet group participants received nutritional education and either free extra virgin olive oil for all the family (1 L/week), or free nuts (30 g/day). Diets were ad libitum. Changes in urine levels of F2-Isoprostane (F2-IP) and the DNA damage base 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) were evaluated at 1-year trial. RESULTS: After 1-year urinary F2-IP decreased in all groups, the decrease in MedDiet groups reaching a borderline significance versus that of the Control group. Urinary 8-oxo-dG was also reduced in all groups, with a higher decrease in both MedDiet groups versus the Control one (P < 0.001). CONCLUSIONS: MedDiet reduces oxidative damage to lipids and DNA in MetS individuals. Data from this study provide evidence to recommend the traditional MedDiet as a useful tool in the MetS management.

Early ROS-mediated DNA damage and oxidative stress biomarkers in Monoclonal B Lymphocytosis.

Monoclonal B Lymphocytosis (MBL) is defined as asymptomatic monoclonal B-cell expansion characterised by a CLL-phenotype, but with less than 5×10(9)/l circulating cells. Reactive oxygen species (ROS)-mediated cell damage plays a critical role in the initiation of carcinogenesis as well as in malignant transformation. The goal of this study was to perform an analysis of the oxidative stress statuses of patients affected by MBL and chronic lymphocytic leukaemia (CLL). We examined peripheral blood and urine specimens from 29 patients with MBL, 55 with CLL and 31 healthy subjects. There was a significant increase in the occurrence of the mutagenic base 8-oxo-2'-deoxiguanosine (8-oxo-dG) in the lymphocytes and urine of MBL and CLL patients compared with controls. Significant differences were also observed in the levels of the lipid peroxidation product malondialdehyde (MDA) and in the oxidised/reduced glutathione (GSSG/GSH) ratio, although an increase in 8-isoprostane was not detected. Interestingly, the antioxidant catalase activity of circulating lymphocytes decreased in the patient groups. In conclusion, early oxidative stress exists in patients with MBL and CLL, causing damage to DNA and lipid structures. The higher levels of 8-oxo-dG in lymphocytes than in urine may be related to a decrease in the capacity of DNA repair systems. There were no differences in the oxidative statuses of the MBL and CLL patients, suggesting that oxidative injuries appear during a pre-leukaemic state of the disease.

Mice lacking thyroid hormone receptor Beta show enhanced apoptosis and delayed liver commitment for proliferation after partial hepatectomy.

BACKGROUND: The role of thyroid hormones and their receptors (TR) during liver regeneration after partial hepatectomy (PH) was studied using genetic and pharmacologic approaches. Roles in liver regeneration have been suggested for T3, but there is no clear evidence distinguishing the contribution of increased amounts of T3 from the modulation by unoccupied TRs. METHODOLOGY/PRINCIPAL FINDINGS: Mice lacking TRalpha1/TRbeta or TRbeta alone fully regenerated liver mass after PH, but showed delayed commitment to the initial round of hepatocyte proliferation and transient but intense apoptosis at 48h post-PH, affecting approximately 30% of the remaining hepatocytes. Pharmacologically induced hypothyroidism yielded similar results. Loss of TR activity was associated with enhanced nitrosative stress in the liver remnant, due to an increase in the activity of the nitric oxide synthase (NOS) 2 and 3, caused by a transient decrease in the concentration of asymmetric dimethylarginine (ADMA), a potent NOS inhibitor. This decrease in the ADMA levels was due to the presence of a higher activity of dimethylarginineaminohydrolase-1 (DDAH-1) in the regenerating liver of animals lacking TRalpha1/TRbeta or TRbeta. DDAH-1 expression and activity was paralleled by the activity of FXR, a transcription factor involved in liver regeneration and up-regulated in the absence of TR. CONCLUSIONS/SIGNIFICANCE: We report that TRs are not required for liver regeneration; however, hypothyroid mice and TRbeta- or TRalpha1/TRbeta-deficient mice exhibit a delay in the restoration of liver mass, suggesting a specific role for TRbeta in liver regeneration. Altered regenerative responses are related with a delay in the expression of cyclins D1 and E, and the occurrence of liver apoptosis in the absence of activated TRbeta that can be prevented by administration of NOS inhibitors. Taken together, these results indicate that TRbeta contributes significantly to the rapid initial round of hepatocyte proliferation following PH, and improves the survival of the regenerating liver at later times.

Impact of cardiovascular risk factors on oxidative stress and DNA damage in a high risk Mediterranean population.

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

[8-oxo-7,8-dihydro-2'-deoxyguanosine as a marker of DNA oxidative stress in individuals with combined familiar hyperlipidemia]. / Estudio de los valores de 8-oxo-7,8-dihidro-2'-desoxiguanosina como marcador de estrés oxidativo del ADN en pacientes con hiperlipemia familiar combinada.

BACKGROUND AND OBJECTIVE: To compare 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) value as an indicator of oxidative stress situation between healthy and familial combined hyperlipidemic (FCH) subjects as a mixed dislipidemia with insulin resistance model and early coronary heart disease, and to study its relationship with clinical-biologic parameters of insulin resistance. SUBJECTS AND METHOD: 40 non-related FCH patients (15 women) and 20 normolipidemic and nondiabetic healthy subjects (8 women) were studied. Clinical, anthropometric and biochemical parameters (lipidic profile, glucemia, insulinemia and 8-oxo-dG) were measured in fasting state in all. RESULTS: Both groups had similar age, body mass index blood pressure and waist perimeter values. Insulin and 8-oxo-dG values were significantly higher in FHC subjects. These differences were maintained after correcting by waist perimeter. 8-oxo-dG correlated positively with insulin and trygliceride; and negatively with high density lipoprotein cholesterol in FCH subjects. CONCLUSIONS: Insulin values are independently correlated with oxidative stress degree measured as 8-oxo-dG.

Estudio de los valores de 8-oxo-7, 8-dihidro-2’-desoxiguanosina como marcador de estrés oxidativo del ADN en pacientes con hiperlipemia familiar combinada / 8-oxo-7, 8-dihydro-2’-deoxyguanosine as a marker of DNA oxidative stress in individuals with combined familiar hyperlipidemia

FUNDAMENTO Y OBJETIVO: Comparar los valores de 8-oxo-7,8-dihidro-2’-desoxiguanosina (8-oxo-dG) como marcador de estrés oxidativo entre personas sanas y pacientes con hiperlipemia familiar combinada (HFC), modelo de dislipemia mixta con resistencia a la insulina y cardiopatía isquémica precoz, y estudiar su relación con parámetros clinicobiológicos de resistencia a la insulina.SUJETOS Y MÉTODO: Se ha analizado a 40 pacientes (15 mujeres) no relacionados entre sí y diagnosticadosde HFC y a 20 sujetos sanos (8 mujeres) normolipémicos y no diabéticos. Se recogieron de forma estandarizada parámetros clínicos, antropométricos y bioquímicos: perfil lipídico, glucemia e insulinemia basales y determinación de 8-oxo-dG.RESULTADOS: Ambos grupos tenían similar edad, índice de masa corporal, cifras de presión arterialy perímetro de cintura. Los valores de insulina y de 8-oxo-dG fueron significativamente mayores en los pacientes con HFC, diferencias que se mantuvieron al corregir por el perímetro de la cintura. Se encontró una relación significativa positiva de 8-oxo-dG con insulina y triglicéridos, y negativa con el colesterol unido a lipoproteínas de alta densidad en los pacientes conHFC

BACKGROUND AND OBJECTIVE: To compare 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxo-dG) value as an indicator of oxidative stress situation between healthy and familial combined hyperlipidemic (FCH) subjects as a mixed dislipidemia with insulin resistance model and early coronary heart disease, and to study its relationship with clinical-biologic parameters of insulin resistance.SUBJECTS AND METHOD: 40 non-related FCH patients (15 women) and 20 normolipidemic and nondiabetic healthy subjects (8 women) were studied. Clinical, anthropometric and biochemical parameters (lipidic profile, glucemia, insulinemia and 8-oxo-dG) were measured in fasting state in all.RESULTS: Both groups had similar age, body mass index blood pressure and waist perimeter values.Insulin and 8-oxo-dG values were significantly higher in FHC subjects. These differences were maintained after correcting by waist perimeter. 8-oxo-dG correlated positively with insulin and trygliceride; and negatively with high density lipoprotein cholesterol in FCH subjects.CONCLUSIONS: Insulin values are independently correlated with oxidative stress degree measuredas 8-oxo-dG (AU)

Insulin resistance and oxidative stress in familial combined hyperlipidemia.

Oxidative stress is associated with atherosclerosis. Familial combined hyperlipidemia (FCH) is considered as a human model of primary dyslipidemia and atherosclerosis frequently associated with insulin resistance (IR), but there are few data on its possible relation to oxidative stress. The objective of this study was to evaluate oxidative stress status using different markers in subjects with FCH assessing its possible correlation with anthropometric parameters and IR. This was a cross-sectional study. A cohort of 40 FCH patients (20 with IR (HOMA>or=3.2) and 20 without IR (HOMA<3.2)), and 20 healthy volunteers were included, all of them non-diabetic, normotensive and non-smokers. We measured lipid profile, glucose and insulin levels in plasma, HOMA, and representative indicators of oxidative stress such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), reduced glutathione (GSH), oxidized glutathione (GSSG) and GSSG/GSH ratio in mononuclear cells. All parameters were determined at basal conditions with standard methodology in the three groups. All FCH subjects showed an increased status of oxidative stress compared to the control group. When the impact of IR was investigated, significant differences between groups were observed in terms of increased levels of 8-oxo-dG, GSSG and GSSG/GSH ratio in FCH subjects with IR indicating higher levels of oxidative stress in these patients. Correlation studies showed that 8-oxo-dG and GSSG/GSH ratio are independently related to IR with odds ratio of 3.5 and 7.4, respectively. We conclude that FCH is related to oxidative stress, especially in the presence of IR.