Is obesity associated with oxidative stress in children?

Circulating Selenium Level Was Positively Related to Visceral Adiposity Index with a Non-linear Trend: a Nationwide Study of the General Population

Selenium plays a role in obesity. However, whether circulating selenium levels are related to the visceral adiposity index (VAI), an indicator of obesity, is still unknown. Based on the National Health and Nutrition Examination Survey (NHANES) 2011-2018, data from 12,777 individuals aged ≥ 20 years were analyzed to clarify this question. In fully adjusted models of multivariate regression analysis, natural logarithm (Ln) selenium was positively related to Ln VAI (β = 0.41; 95% confidence interval [CI], 0.27, 0.55; P < 0.001). Compared with the lowest quartile of Ln selenium, the highest quartile was also positively associated with Ln VAI (β = 0.16; 95% CI, 0.11, 0.21; P < 0.001). Moreover, we found that this positive connection was non-linear. When Ln selenium was less than the inflection point, Ln selenium was positively related to Ln VAI (β = 0.41; 95% CI, 0.31, 0.52; P < 0.001). However, when Ln selenium was greater than or equal to the inflection point, Ln selenium was not significantly related to Ln VAI (β = -0.15; 95% CI, -0.56, 0.25; P = 0.455). In subgroup analysis, significant interactions were observed with age and sex (P for interaction < 0.05). Stronger interactions were observed among middle-aged participants (β = 0.65; 95% CI, 0.31, 0.98; P = 0.002) and males (β = 0.61; 95% CI, 0.43, 0.79; P < 0.001). Overall, circulating selenium levels were positively related to VAI, with a non-linear trend. Prospective studies and interventional experiments are necessary to verify the possible mechanisms.

Obesity Is Associated with Oxidative Stress Markers and Antioxidant Enzyme Activity in Mexican Children

The relationship between metabolic disorders and oxidative stress is still controversial in the child population. The present cross-sectional study aimed to analyze the associations between obesity, cardiometabolic traits, serum level of carbonylated proteins (CPs), malondialdehyde (MDA), and the enzyme activity of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in children from Mexico City (normal weight: 120; obesity: 81). Obesity resulted in being positively associated with CAT (β = 0.05 ± 0.01, p = 5.0 × 10-3) and GPx (β = 0.13 ± 0.01, p = 3.7 × 10-19) enzyme activity. A significant interaction between obesity and sex was observed in MDA and SOD enzymatic activity (PMDA = 0.03; PSOD = 0.04). The associations between obesity, MDA level, and SOD enzyme activity were only significant in boys (boys: PMDA = 3.0 × 10-3; PSOD = 7.0 × 10-3; girls: p ≥ 0.79). In both children with normal weight and those with obesity, CP levels were positively associated with SOD enzyme activity (PNormal-weight = 2.2 × 10-3; PObesity = 0.03). In conclusion, in Mexican children, obesity is positively associated with CAT and GPx enzyme activity, and its associations with MDA levels and SOD enzyme activity are sex-specific. Therefore, CP level is positively related to SOD enzyme activity independently of body weight.

Association of dietary antioxidant index with body mass index in adolescents

Background

Dietary antioxidants may decrease body fat through reduction of oxidative stress. This study aimed to examine the association between dietary antioxidant index (DAI) and body mass index (BMI) in adolescent boys.

Methods

In this cross-sectional study, 593 adolescent boys aged 12-16 years were randomly selected and were divided into two groups of overweight and non-overweight individuals. Data on physical activity and anthropometric measurements were collected. Dietary intake was assessed using 168-item semi quantitative food frequency questionnaire and the DAI score was calculated to measure the antioxidant capacity of the diet.

Results

The overweight adolescents had higher intake of energy (2490.55 ± 632.49 vs. 2354.33 ± 632.64 kcal/d, p = 0.01), carbohydrate (290.21 ± 71.41 vs. 272.93 ± 79.22 g/d, p = 0.01), fat (111.51 ± 40.76 vs. 104.51 ± 35.56 g/d, p = 0.04), calcium (811.70 ± 283.70 vs. 741.06 ± 251.17 g/d, p = 0.003), and vitamin D (1.41 ± 1.17 vs. 1.18 ± 1.19 μg/d, p = 0.031) in comparison with normal weight adolescents. The DAI had an inverse association with BMI after adjustment for age and caloric intake (OR: 0.85, 95% CI: 0.76-0.96, p = 0.009). Additional adjustment for dietary intake of vitamin A, vitamin E, vitamin C, zinc, manganese, and selenium did not change the results.

Conclusion

The results of the study showed that following a diet rich in antioxidants may be effective in preventing obesity in adolescent boys. Further longitudinal studies are needed to confirm these finding and to determine the underlying mechanisms.

Exercise Outcomes in Childhood Obesity-Related Inflammation and Oxidative Status

Childhood obesity is identified as one of the major public health issues to increase the risk for cardiometabolic diseases and related complications in adulthood. The literature has supported inflammation and oxidative stress as the primary underlying mechanisms involved in the pathogenesis of obesity-related diseases. Epidemiological evidence consistently shows the benefits of physical activity in the improvement of obesity-mediated inflammation and oxidative stress status. In this narrative mini-review, the available scientific evidence on the potential effects of exercise in alleviating these susceptibilities in childhood obesity will be assessed.

Nutritional Status Influences Oxidative Stress and Insulin Resistance in Preschool Children

Background: Child malnutrition represents a major public health problem with physiological, psychological, and social short- and long-term implications. Objective: To compare the influence of nutritional status on oxidative stress (OS) markers in children aged 3-6 years. Methods: Children were categorized into four groups: underweight, normal weight, overweight, and obesity. Glucose (Glu), cholesterol (Chol), high-density lipoproteins, insulin, triacylglycerols (TG), triacylglycerols/glucose (TyG) index, and the homeostasis model assessment of insulin resistance (HOMA-IR) were analyzed. In addition, OS [malondialdehyde (MDA) and 3-nitrotyrosine (3-NT)] and antioxidant defense markers [superoxide dismutase (SOD), catalase (CAT), and the ratio of reduced/oxidized glutathione (GSH/GSSG)] were quantified. Results: Children with obesity showed significantly higher levels of MDA and 3-NT, and increased SOD activity compared with normal weight children. Glu, Chol, TG levels, TyG indexes, HOMA-IR, MDA, 3-NT, and SOD positively correlated with body mass index (BMI) and Centers for Disease Control and Prevention percentiles (CDC PC). However, CAT concentration and the GSH/GSSG ratio correlated negatively with BMI and CDC PC. In children with underweight, we found a positive correlation of TG levels and TyG indexes with BMI, whereas both markers positively correlated with BMI and CDC PC in children with overweight. MDA negatively correlated with BMI in children with underweight, while a positive association was observed in children with overweight. Finally, SOD, CAT, and GSH/GSSG negatively correlated with both BMI and CDC PC in children with overweight. Conclusions: Malnutrition, especially obesity, is associated with metabolic and OS disturbances in preschool children. It is urgent to design strategies to prevent malnutrition in this age group since this stage of development is crucial to potentially avoid future co-morbidities.

Hipótesis sobre las conexiones entre COVID-19 severo en niños y nutrición: una revisión narrativa

Introduction

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2). Compared with adults, children with SARS-CoV-2 infection may have fewer and less severe symptoms. Gastrointestinal symptoms are commonly reported in children, sometimes as the only manifestation of the disease, and most often manifest as anorexia, diarrhea, nausea and vomiting, or abdominal pain. Although most children have asymptomatic or mild disease, 10 % of those infected may experience serious or critical disease, or even death. Multisystem inflammatory syndrome is a rare but serious condition recently reported in children with COVID-19. Studies indicate that children with obesity are at higher risk of developing severe COVID-19, and inflammation associated with obesity could be one of the factors that worsens COVID-19 symptoms due to an increased inflammatory response involving molecules such as interleukin 6, tumor necrosis factor alpha, and monocyte chemoattractant protein. On the other hand, evidence has been reported of a higher protein expression of ACE2 in the visceral adipose tissue of obese and malnourished humans, and this could be associated with complications and severity of COVID-19. Therefore, regulation of the intake of macronutrients or micronutrients could be used as a strategy to reduce the consequences of COVID-19. Diet in general and bioactive compounds could play an important role in the prevention of the inflammatory cascade. The micronutrients with the most evidence suggesting a role in immune support are vitamins C and D, zinc, and polyphenols.

Reduced plasma carotenoids in individuals suffering from metabolic diseases with disturbances in lipid metabolism: a systematic review and meta-analysis of observational studies

This review summarises the association between serum carotenoids, serum retinoids and dietary intake outcomes with obesity/overweight and individuals with metabolic diseases with disturbances in lipid metabolism. Observational studies reporting dietary intakes and serum concentrations of carotenoids and retinol were collected from Medline and Web of Science. Mean differences were calculated between "cases" (classified as obese, overweight or having a metabolic disease with disturbances in lipid metabolism; i.e. non-alcoholic fatty liver disease, type 2 diabetes, dyslipidaemia or metabolic syndrome) and "comparator group" (classified as normal weight healthy individuals) and summarised in meta-analyses. Significant summary measures were observed for most serum provitamin A and non-provitamin A carotenoids. Studies reporting total serum carotenoids had shown the greatest decrease (-0.28 µmol/l [-0.33, -0.23], p<.001, I²=62.5%, n = 7). There were no significant summary measures for dietary outcomes, suggesting a physiological role of low serum carotenoids in the development of obesity and associated diseases.

Blunted Reducing Power Generation in Erythrocytes Contributes to Oxidative Stress in Prepubertal Obese Children with Insulin Resistance

Childhood obesity, and specifically its metabolic complications, are related to deficient antioxidant capacity and oxidative stress. Erythrocytes are constantly exposed to multiple sources of oxidative stress; hence, they are equipped with powerful antioxidant mechanisms requiring permanent reducing power generation and turnover. Glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) are two key enzymes on the pentose phosphate pathway. Both enzymes supply reducing power by generating NADPH, which is essential for maintaining the redox balance within the cell and the activity of other antioxidant enzymes. We hypothesized that obese children with insulin resistance would exhibit blunted G6PDH and 6PGDH activities, contributing to their erythrocytes’ redox status imbalances. We studied 15 control and 24 obese prepubertal children, 12 of whom were insulin-resistant according to an oral glucose tolerance test (OGTT). We analyzed erythroid malondialdehyde (MDA) and carbonyl group levels as oxidative stress markers. NADP+/NADPH and GSH/GSSG were measured to determine redox status, and NADPH production by both G6PDH and 6PGDH was assayed spectrophotometrically to characterize pentose phosphate pathway activity. Finally, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR) activities were also assessed. As expected, MDA and carbonyl groups levels were higher at baseline and along the OGTT in insulin-resistant children. Both redox indicators showed an imbalance in favor of the oxidized forms along the OGTT in the insulin-resistant obese group. Additionally, the NADPH synthesis, as well as GR activity, were decreased. H₂O₂ removing enzyme activities were depleted at baseline in both obese groups, although after sugar intake only metabolically healthy obese participants were able to maintain their catalase activity. No change was detected in SOD activity between groups. Our results show that obese children with insulin resistance present higher levels of oxidative damage, blunted capacity to generate reducing power, and hampered function of key NADPH-dependent antioxidant enzymes.

Relationship Between Plasma Copper Concentration and Body Fat Distribution in Children in China: a Cross-Sectional Study

This study aimed to explore the association of the plasma copper concentration with body fat distribution and the potential mediating effect of inflammation status in children. A total of 454 children were recruited in this study. Dual-energy X-ray absorptiometry was applied to measure the fat mass (FM) and fat mass percentages (FM%) at whole body, trunk, appendicular, android, and gynoid regions. Android to gynoid fat mass ratio and fat mass to lean mass (FM/LM) ratio at whole body, trunk, and appendicular sites were calculated. Plasma copper concentration was measured via inductively coupled plasma mass spectrometry. C-reactive protein (CRP) was determined by ELISA. After adjusting for covariates, multiple linear regression analyses showed that, for every additional unit increase in the plasma copper concentration, the FM, FM%, and FM/LM at whole body and subregions increased by 0.030-0.472 kg (P < 0.001-0.019), 0.013-1.04% (P = 0.007-0.042), and 0.021-0.030 (P < 0.001), respectively. Mediating analysis suggested that CRP significantly mediated 22.0-30.6% (P < 0.001) of the estimated association of copper with FM% and FM/LM at whole body and limbs. Thus, children with higher plasma levels of copper tended to have a higher regional and overall body fat deposition, and this relationship was partly mediated by inflammatory status.

Magnesium, Oxidative Stress, Inflammation, and Cardiovascular Disease

Hypomagnesemia is commonly observed in heart failure, diabetes mellitus, hypertension, and cardiovascular diseases. Low serum magnesium (Mg) is a predictor for cardiovascular and all-cause mortality and treating Mg deficiency may help prevent cardiovascular disease. In this review, we discuss the possible mechanisms by which Mg deficiency plays detrimental roles in cardiovascular diseases and review the results of clinical trials of Mg supplementation for heart failure, arrhythmias and other cardiovascular diseases.

Antioxidant Enzymes Haplotypes and Polymorphisms Associated with Obesity in Mexican Children

Obesity is a major health problem worldwide and constitutes a sanitary emergency in Mexico, especially childhood obesity. Several studies have proved the relationship between obesity and oxidative stress and the influence of genetic predisposition. This work was aimed to analyze the association of antioxidant enzyme polymorphisms with overweight and obesity in Mexican children and adolescents. A case-control study was performed in 585 children and adolescents aged 3 to 17 years, using two criteria to classify obesity: body mass index (BMI) and body fat percentage (BFP). Anthropometric and biochemical measurements were carried out, and malondialdehyde serum levels were determined. Genotyping was done with the Axiom Genome-Wide LAT microarray, including 68 single nucleotide polymorphisms (SNPs) of the glutathione peroxidase (GPX) and paraoxonase (PON) families. We found six haplotypes associated with obesity—two of them (one in GPX3 and the other in GPX5 and GPX6) in a protective direction when obesity was classified by BMI. The other four haplotypes were associated with obesity when classification was based on BFP—one of them in GPX3 in a protective direction and the others in PON genes conferring obesity risk. In addition, two SNPs, GPX3 rs922429 and GPX4 rs2074451 showed protection against obesity classified by BFP. This study showed genetic susceptibility to oxidative stress in relation to obesity in Mexican children and opens up the possibility that some genetic loci related to obesity are not identified when weight classification is based on BMI.

Selenium and Selenoproteins in Adipose Tissue Physiology and Obesity

Selenium (Se) homeostasis is tightly related to carbohydrate and lipid metabolism, but its possible roles in obesity development and in adipocyte metabolism are unclear. The objective of the present study is to review the current data on Se status in obesity and to discuss the interference between Se and selenoprotein metabolism in adipocyte physiology and obesity pathogenesis. The overview and meta-analysis of the studies on blood Se and selenoprotein P (SELENOP) levels, as well as glutathione peroxidase (GPX) activity in obese subjects, have yielded heterogenous and even conflicting results. Laboratory studies demonstrate that Se may modulate preadipocyte proliferation and adipogenic differentiation, and also interfere with insulin signaling, and regulate lipolysis. Knockout models have demonstrated that the selenoprotein machinery, including endoplasmic reticulum-resident selenoproteins together with GPXs and thioredoxin reductases (TXNRDs), are tightly related to adipocyte development and functioning. In conclusion, Se and selenoproteins appear to play an essential role in adipose tissue physiology, although human data are inconsistent. Taken together, these findings do not support the utility of Se supplementation to prevent or alleviate obesity in humans. Further human and laboratory studies are required to elucidate associations between Se metabolism and obesity.

Oxidative/Antioxidative Status in Patients after Myocardial Infarction and in Those without Cardiovascular Event Depending on Anthropometric Factors Defining Body Weight

Obesity is one of the factors leading to the development of atherosclerosis. This metabolic disorder is associated with an increased production of reactive oxygen species, which affect the oxidative stress levels. The aim of this study was to evaluate oxidative/antioxidative status and to investigate the correlation between redox markers and anthropometric parameters and body composition in adult patients after myocardial infarction and in individuals without a cardiovascular event in the past. Descriptive data on socio-demographic, clinical, and anthropometric features and blood samples were collected and categorized into two equal groups: after myocardial infarction (study group (SG), n = 80) and without a cardiovascular event (control group (CG), n = 80). The oxidative/antioxidative status was assessed in plasma on the basis of total oxidative/capacitive status (PerOx), total antioxidative status/capacity (ImAnOx), and oxidized low-density lipoprotein (oxLDL). The oxLDL was significantly higher in the CG group compared to the SG group (p = 0.02). No significant differences were found with regard to PerOx and ImAnOx values between the groups studied. A significant positive correlation between PerOx and percentage of adipose tissue (FM%) and body adiposity index (BAI) was found in the two studied groups. ImAnOx significantly positively correlated with visceral adiposity indexes(VAIs) in SG and FM% in CG. OxLDL negatively correlated with body mass index and waist to hip circumference ratio in CG. The total oxidative/antioxidative status is related to the amount of adipose tissue and the BAIs of the subjects. It was observed that it correlates more frequently with the visceral distribution of body fat.

Urinary Biomarkers of Inflammation and Oxidative Stress Are Elevated in Obese Children and Correlate with a Marker of Endothelial Dysfunction

Obesity is a state of chronic low-level inflammation closely associated with oxidative stress. Childhood obesity is associated with endothelial dysfunction, inflammation, and oxidative stress markers individually. This study was aimed at determining the association between the biomarkers of inflammation, oxidative stress, and endothelial dysfunction in urine samples of healthy, overweight, and obese children. Eighty-eight elementary school children aged between 6 and 10 years participated in this study. Anthropometric measurements were measured using WHO recommendations. The biomarkers of low-grade inflammation such as C-reactive protein (CRP), interleukin-6 (IL-6), and α-1-acid glycoprotein (AGP); oxidative stress markers such as 8-isoprostane and 8-hydroxy-2'-deoxyguanosine (8-OHdG); and endothelin-1 (ET-1) were analyzed in urine samples. The area under the curve (AUC) by the receiver operating characteristics (ROC) was analyzed to identify the best urinary biomarker in childhood obesity. Linear regression and Pearson correlation were analyzed to determine the association between the parameters. The obese participants have significantly increased levels of CRP, AGP, IL-6, and 8-isoprostane compared to normal-weight participants. The overweight participants had significantly increased levels of ET-1 and 8-OHdG but not the obese group compared to the NW group. The AUC for urinary CRP (AUC: 0.847, 95% CI: 0.765-0.930; p < 0.0001) and 8-isoprostane (AUC: 0.857, 95% CI: 0.783-0.932; p < 0.0001) showed a greater area under ROC curves compared to other inflammatory and oxidative markers. The urinary CRP and 8-isoprostane significantly correlated with the obesity measures (body mass index, waist circumference, and waist-to- height ratio) and ET-1, inflammatory, and oxidative markers. The increased urinary inflammatory markers and 8-isoprostane can serve as a noninvasive benchmark for early detection of the risk of developing cardiovascular disease.

Vitamin D status, oxidative stress, and inflammation in children and adolescents: A systematic review

Vitamin D deficiency is considered a global public health problem with high prevalence in children and adolescents. The majority of the studies in the literature have identified a relationship between vitamin D insufficiency/deficiency and obesity, as well as other traditional cardiometabolic risk factors in children and adolescents. Scarce studies address vitamin D status with oxidative stress and inflammation in the young population. The aim of this systematic review was to evaluate the evidence of the association of vitamin D status with oxidative stress and inflammation in children and adolescents. This is a systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) guideline on reporting systematic reviews. Eight studies were selected for this review. All included studies evaluated inflammatory biomarkers and two out of eight evaluated biomarkers of oxidative stress. The majority of the studies (five out of eight) found association of vitamin D status with biomarkers of oxidative stress and inflammation such as C-reactive protein (CRP), interleukin-6 (IL-6), cathepsin S, vascular cell adhesion molecule-1 (VCAM-1), malondialdehyde (MDA), myeloperoxidase, 3-nitrotyrosine, and superoxide dismutase (SOD). Vitamin D status is associated with oxidative stress and inflammation in the majority of the studies with children and adolescents. Thus, the assessment of vitamin D status is important because it is associated with nontraditional cardiometabolic markers in the pediatric population (review registration: PROSPERO CRD42018109307).

Molecular aspects of pancreatic β-cell dysfunction: Oxidative stress, microRNA, and long noncoding RNA

Metabolic syndrome is known as a frequent precursor of type 2 diabetes mellitus (T2D). This disease could affect 8% of the people worldwide. Given that pancreatic β-cell dysfunction and loss have central roles in the initiation and progression of the disease, the understanding of cellular and molecular pathways associated with pancreatic β-cell dysfunction can provide more information about the underlying pathways involved in T2D. Multiple lines evidence indicated that oxidative stress, microRNA, and long noncoding RNA play significant roles in various steps of diseases. Oxidative stress is one of the important factors involved in T2D pathogenesis. This could affect the function and survival of the β cell via activation or inhibition of several processes and targets, such as receptor-signal transduction, enzyme activity, gene expression, ion channel transport, and apoptosis. Besides oxidative stress, microRNAs and noncoding RNAs have emerged as epigenetic regulators that could affect pancreatic β-cell dysfunction. These molecules exert their effects via targeting a variety of cellular and molecular pathways involved in T2D pathogenesis. Here, we summarized the molecular aspects of pancreatic β-cell dysfunction. Moreover, we highlighted the roles of oxidative stress, microRNAs, and noncoding RNAs in pancreatic β-cell dysfunction.

Interplay between diet-induced obesity and oxidative stress: Comparison between Drosophila and mammals

Obesity caused by excessive fat accumulation in adipocytes is a growing global problem and is a major contributing risk factor for many chronic metabolic diseases. There is increasing evidence that oxidative stress plays a crucial role in both obesity progression and obesity-related complications. In recent years, Drosophila models of diet-induced obesity and associated pathologies have been successfully developed through manipulation of carbohydrate or fat concentrations in the food. Obese flies accumulate triacylglycerols in the fat body, an organ homologous to mammalian adipose tissue and exhibit metabolic and physiological complications including hyperglycemia, redox imbalance and shortened longevity; these are all similar to those observed in obese humans. In this review, we summarize current data on the mechanisms of oxidative stress induction in obesity, with emphasis on metabolic switches and the involvement of redox-responsive signaling pathways such as NF-κB and Nfr2. The recent achievements with D. melanogaster model suggest a complicated relationship between obesity, oxidative stress, and longevity but the Drosophila model offers probably the best opportunities to delve further into unraveling these interactions, particularly the roles of antioxidants and of Nrf2-regulated responses, in order to increase our understanding of the obese metabolic phenotype and test and develop anti-obesity pharmaceuticals.

The Effect of Treadmill Treatment on Oxidative Stress Markers and Endogenous Antioxidant Status in Obesity Mice

AIM:

This study aimed to determine the effect of treadmill treatment on oxidative stress markers and endogenous antioxidant status seen from MDA, GSH, MnSOD enzyme specific activity and blood catalase of obese mice.

MATERIALS AND METHODS:

This research is experimental laboratory research using post-test control design group only. The study lasted for 28 days and was divided into 4 groups of study, i.e., group K (normal control), KP (obesity control), P1 (obesity mice with 1 x 10-minute treadmill treatment a day), and P2 (obesity mice with 2 x 10-minute treadmill treatment a day).

RESULTS:

The treadmill treatment had an effect on the improvement of the oxidative status of mice with a decrease of MDA level of obesity mice blood (p ≤ 0.05) compared to KP control. An elevated endogenous antioxidant status of obesity mice was seen from elevated GSH levels, MnSOD specific activity and blood catalase of obesity mice (p ≤ 0.05) compared with KP controls. Treatment of 1 x 10-minute treadmill per day decreased blood MDA level, increased GSH enzyme and increased specific activity of MnSOD enzyme and blood catalase of obese mice.

CONCLUSIONS:

The 2 x 10-minute daily treadmill did not differ significantly in improving the oxidative status and endogenous antioxidant status compared with the treadmill 1 x 10 minutes a day (p ≥ 0.05).

Oral nicotine aggravates endothelial dysfunction and vascular inflammation in diet-induced obese rats: Role of macrophage TNFα

Obesity and cigarette smoke are major cardiovascular (CV) risk factors and, when coexisting in the same individuals, have additive/synergistic effects upon CVD. We studied the mechanisms involved in nicotine enhancement of CVD in Sprague Dawley rats with diet–induced obesity. The rats were fed either a high fat (HFD) or normal rat chow diet with or without nicotine (100 mg/L in drinking water) for 20 weeks. HFD rats developed central obesity, increased systolic blood pressure (SBP), aortic superoxide (O₂^-) production, and impaired endothelial nitric oxide synthase (eNOS) and endothelium-dependent relaxation to acetylcholine (EDR). Nicotine further increased SBP, O₂^- and impaired eNOS and EDR in obese rats. In the peritoneal macrophages from obese rats, tumor necrosis factor (TNF) α, interleukin 1β and CD36 were increased, and were further increased in nicotine-treated obese rats. Using PCR array we found that 3 of 84 target proinflammatory genes were increased by 2–4 fold in the aorta of obese rats, 11 of the target genes were further increased in nicotine-treated obese rats. HUVECs, incubated with conditioned medium from the peritoneal macrophages of nicotine treated-obese rats, exhibited reduced eNOS and increased NADPH oxidase subunits gp91phox and p22phox expression. Those effects were partially prevented by adding anti-TNFα antibody to the conditioned medium. Our results suggest that nicotine aggravates the CV effects of diet–induced obesity including the oxidative stress, vascular inflammation and endothelial dysfunction. The underlying mechanisms may involve in targeting endothelium by enhancement of macrophage-derived TNFα.

Total Oxidant and Antioxidant Status in Prepubertal Children with Obesity

Aims

Obesity is accompanied by the formation of oxygen free radicals, whose intensified activity without effective defense mechanisms can lead to oxidative stress and related complications. We evaluated the presence of oxidative stress in obese prepubertal children.

Methods

The study included 83 healthy children aged 2–10 years (62 with obesity and 21 nonobese controls). Total oxidant capacity (TOC), total antioxidant capacity (TAC), oxidized low-density lipoprotein (ox-LDL), lipid parameters, glucose, and C-reactive protein (CRP) were measured in serum. Oxidative stress index (OSI) was calculated.

Results

Serum TOC concentration was significantly higher (p < 0.05) and TAC concentration was lower (p < 0.05) in obese children. OSI was higher (p < 0.01) in obese subjects compared with controls. CRP levels were normal in all children, but median CRP value was higher (p < 0.01) and HDL cholesterol levels were lower (p < 0.05) in the obese group. We found a significant negative correlation between TAC and ox-LDL concentrations (r = −0.27, p < 0.05) in obese children. Furthermore, obesity duration was positively correlated with TOC level (r = 0.32, p < 0.05) in this group.

Conclusions

Obesity-related oxidative stress already occurs in prepubescence. Early obesity diagnosis and the necessary therapeutic activity implementation is a vital strategy for the prophylaxis of free radical damage and related multiorgan complications.

Role of Magnesium in Oxidative Stress in Individuals with Obesity

Adipose tissue is considered an endocrine organ that promotes excessive production of reactive oxygen species when in excess, thus contributing to lipid peroxidation. Magnesium deficiency contributes to the development of oxidative stress in obese individuals, as this mineral plays a role as an antioxidant, participates as a cofactor of several enzymes, maintains cell membrane stability and mitigates the effects of oxidative stress. The objective of this review is to bring together updated information on the participation of magnesium in the oxidative stress present in obesity. We conducted a search of articles published in the PubMed, SciELO and LILACS databases, using the keywords 'magnesium', 'oxidative stress', 'malondialdehyde', 'superoxide dismutase', 'glutathione peroxidase', 'reactive oxygen species', 'inflammation' and 'obesity'. The studies show that obese subjects have low serum concentrations of magnesium, as well as high concentrations of oxidative stress marker in these individuals. Furthermore, it is evident that the adequate intake of magnesium contributes to its appropriate homeostasis in the body. Thus, this review of current research can help define the need for intervention with supplementation of this mineral for the prevention and treatment of disorders associated with this chronic disease.

Association of myeloperoxidase levels with cardiometabolic factors and renal function in prepubertal children

INTRODUCTION

Myeloperoxidase (MPO), an enzyme linking obesity and cardiovascular (CV) risk in adults, has rarely been studied in young children and no studies assessed its association with renal function. We sought to explore a possible association between serum MPO levels, obesity, CV risk factors and renal function in prepubertal children.

MATERIALS/METHODS

Cross-sectional evaluation of 309 children aged 8-9 years (161 normal weight, 148 overweight/obese), members of the birth cohort Generation I (Portugal). Anthropometrics (body mass index (BMI), waist-to-height ratio (WHtR) and % body fat mass (%BFM) by bioelectrical impedance analysis), 24-h ambulatory blood pressure monitoring and pulse wave velocity (PWV) were measured. Insulin resistance was estimated by the HOMA index (considering serum fasting glucose and insulin determinations). Serum MPO levels were assessed by immunoenzymatic assay.

RESULTS

MPO levels were positively associated with obesity indices (BMI z-score, WHtR and %BFM). Higher MPO levels were associated with higher 24-h and night-time mean arterial pressure, with nondipping and with higher values of insulin resistance. In normal weight children, the endothelial function, as evaluated indirectly by PWV, was an independent predictor of MPO levels. In overweight/obese children, estimated glomerular filtration rate increased significantly across tertiles of MPO (Ptrend = 0·031) and this association held after adjustment for age, sex, neutrophil and monocyte counts and CV risk factors.

CONCLUSIONS

Our results reinforce the role of MPO as a risk marker in obesity and related CV morbidities in young children. MPO levels associate with the dipping pattern and PWV and, among overweight/obese children, an association exists between MPO and renal function.

Relation between plasma antioxidant vitamin levels, adiposity and cardio-metabolic profile in adolescents: Effects of a multidisciplinary obesity programme

BACKGROUND & AIMS

In vivo and in vitro evidence suggests that antioxidant vitamins and carotenoids may be key factors in the treatment and prevention of obesity and obesity-associated disorders. Hence, the objective of the present study was to determine the relationship between plasma lipid-soluble antioxidant vitamin and carotenoid levels and adiposity and cardio-metabolic risk markers in overweight and obese adolescents participating in a multidisciplinary weight loss programme.

METHODS

A therapeutic programme was conducted with 103 adolescents aged 12-17 years old and diagnosed with overweight or obesity. Plasma concentrations of α-tocopherol, retinol, β-carotene and lycopene, anthropometric indicators of general and central adiposity, blood pressure and biochemical parameters were analysed at baseline and at 2 and 6 months of treatment.

RESULTS

Lipid-corrected retinol (P < 0.05), β-carotene (P = 0.001) and α-tocopherol (P < 0.001) plasma levels increased significantly, whereas lipid-corrected lycopene levels remained unaltered during the treatment. Anthropometric indicators of adiposity (P < 0.001), blood pressure (P < 0.01) and biochemical parameters (P < 0.05) decreased significantly, whereas fat free mass increased significantly (P < 0.001). These clinical and biochemical improvements were related to changes in plasma lipid-corrected antioxidant vitamin and carotenoid levels. The adolescents who experienced the greatest weight loss also showed the largest decrease in anthropometric indicators of adiposity and biochemical parameters and the highest increase in fat free mass. Weight loss in these adolescents was related to an increase in plasma levels of lipid-corrected α-tocopherol (P = 0.001), β-carotene (P = 0.034) and lycopene (P = 0.019).

CONCLUSIONS

Plasma lipid-soluble antioxidant vitamin and carotenoid levels are associated with reduced adiposity, greater weight loss and an improved cardio-metabolic profile in overweight and obese adolescents.

Decreased renal function in overweight and obese prepubertal children

BACKGROUND

Obesity is a potentially modifiable risk factor for the development and progression of kidney disease, both in adults and children. We aim to study the association of obesity and renal function in children, by comparing estimated glomerular filtration rate (eGFR) in nonoverweight and overweight/obese children. Secondarily, we aim to evaluate the accuracy of equations on eGFR estimation when compared to 24-h urinary creatinine clearance (CrCl).

METHODS

Cross-sectional study of 313 children aged 8-9 y, followed in the birth cohort Generation XXI (Portugal). Creatinine and cystatin C, GFR estimated by several formulas and CrCl were compared in 163 nonoverweight and 150 overweight/obese, according to World Health Organization growth reference.

RESULTS

Overweight/obese children had significantly lower eGFR, estimated by all methods, except for CrCl and revised Schwartz formula. Despite all children having renal function in the normal range, eGFR decreased significantly with BMI z-score (differences ranging from -4.3 to -1.1 ml/min/1.73 m(2) per standard deviation of BMI). The Zappitelli combined formula presented the closest performance to CrCl, with higher correlation coefficients and higher accuracy values.

CONCLUSION

Young prepubertal children with overweight/obesity already present significantly lower GFR estimations that likely represent some degree of renal impairment associated with the complex deleterious effects of adiposity.

Pro-inflammatory adipocytokines, oxidative stress, insulin, Zn and Cu: Interrelations with obesity in Egyptian non-diabetic obese children and adolescents

PURPOSE

To investigate the inter-relationships between adipocytokines, oxidative stress, insulin, Zn and Cu and obesity among Egyptian obese non-diabetic children and adolescents.

PATIENTS AND METHODS

72 obese children and adolescents of both sexes (5-17 years) were recruited for the study. 40 healthy normal non-obese persons of matched ages and sexes were used as control group. Lipid profile, tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and leptin levels were measured. Malondialdehyde (MDA) and reduced glutathione (GSH) concentrations and superoxide dismutase (SOD) activity were estimated. Micronutrients (Zn and Cu) concentrations in addition to insulin and fasting blood sugar (FBS) levels were also evaluated. Estimation of insulin resistance (homeostatic model assessment (HOMA-IR)) was derived from FBS measurements.

RESULTS

Significant elevations (P<0.001) in TNF-α, IL-6, leptin, MDA, Cu and FBS levels and significant decreases (P<0.001) in GSH, Zn levels and SOD activity were detected among obese individuals as compared with control group. Insulin and triglyceride levels were significantly increased in obese male children and HDL-cholesterol level was increased significantly in obese adolescent females compared to controls. However, total cholesterol and LDL-cholesterol levels were significantly high in all obese cases as compared with controls. Insulin resistance was detected in 100% of the patients.

CONCLUSIONS

We concluded that obesity with pro-inflammatory adipocytokines and hypozincemia together by many mechanisms participate in excessive oxidative stress and are highly associated with inflammation and the development of obesity-related complications. Obesity represents a critical risk factor for development of insulin resistance status.

Effects of synbiotic on anthropometry, lipid profile and oxidative stress in obese children

Recent studies have suggested some beneficial effects of probiotics and/or prebiotics on obesity in adults; such experience is limited in children and adolescents. This study was an open-label, randomised, controlled study including children with primary obesity. The first group was treated with a standard method with a reduced calorie intake and increased physical activity. The second group received add-on daily synbiotic supplementation during one month. The aim of this study was to evaluate potential effects of a synbiotic on anthropometric measurements, lipid profile and oxidative stress parameters. One month of supplementation of the synbiotic resulted in a significant reduction of weight (P<0.001) and body mass index (P<0.01). Changes (% reduction comparing to baseline) in anthropometric measurements, were significantly higher in the children receiving the additional synbiotic supplement (P<0.05). The percentage of children with weight loss was higher in the synbiotic group, but not statistically significant (71.4 vs 64.2%, P>0.05). At the 30(th) day of synbiotic intervention, serum total cholesterol, low density lipoprotein cholesterol and total oxidative stress levels significantly declined (P<0.05). Changes in serum lipid levels were significantly higher in the synbiotic group (P<0.05). Changes in serum total oxidative stress levels before and after the intervention period, were significant in synbiotic group (P<0.01). In our study, changes in weight, body mass index, and triceps skinfold thickness were higher in the group receiving the one month synbiotic supplement thin in the standard method group. The supplement tested also had a beneficial effect on lipid profile and total oxidative stress. To the best of our knowledge, this is the first study showing the effects of synbiotics on oxidative stress in obese patients with an additional effect on weight loss regarding to previous studies.

Impact of exercise training without caloric restriction on inflammation, insulin resistance and visceral fat mass in obese adolescents

BACKGROUND

Exercise training has been shown to improve cardiometabolic health in obese adolescents.

OBJECTIVES

Evaluate the impact of a 12-week exercise-training programme (without caloric restriction) on obese adolescents' cardiometabolic and vascular risk profiles.

METHODS

We measured systemic markers of oxidation, inflammation, metabolic variables and endothelial function in 20 obese adolescents (OB) (age: 14.5 ± 1.5 years; body mass index: 34.0 ± 4.7 kg m(-2) ) and 20 age- and gender-matched normal-weight adolescents (NW). Body composition was assessed by magnetic resonance imagery. Peak aerobic capacity and maximal fat oxidation were evaluated during specific incremental exercise tests. OB participated in a 12-week exercise-training programme.

RESULTS

OB presented lower peak aerobic capacity (24.2 ± 5.9 vs. 39.8 ± 8.3 mL kg(-1)  min(-1) , P < 0.05) and maximal fat oxidation compared with NW (P < 0.05). OB displayed greater F2t-Isoprostanes (20.5 ± 6.7 vs. 13.4 ± 4.2 ng mmol(-1) creatinine), Interleukin-1 receptor antagonist (IL-1Ra) (1794.8 ± 532.2 vs. 835.1 ± 1027.4 pg mL(-1) ), Tumor Necrosis Factor-α (TNF-α) (2.1 ± 1.2 vs. 1.5 ± 1.0 pg mL(-1) ), Soluble Tumor Necrosis Factor-α Type II Receptor (sTNFαRII), leptin, insulin, homeostasis model assessment of insulin resistance, version 2 (HOMA2-IR), high-sensitive C-reactive protein, triglycerides and lower adiponectin and high-density lipoprotein cholesterol (all P < 0.05). After exercise training, despite lack of weight loss, VO2peak (mL.kg(-1) .min(-1) ) and maximal fat oxidation increased (P < 0.05). IL-1Ra and IFN-gamma-inducible protein 10 (IP-10) decreased (P < 0.05). Insulin and HOMA2-IR decreased (14.8 ± 1.5 vs. 10.2 ± 4.2 μUI mL(-1) and 1.9 ± 0.8 vs. 1.3 ± 0.6, respectively, P < 0.05). Change in visceral fat mass was inversely associated with change in maximal fat oxidation (r = -0.54; P = 0.024). The subgroup of participants that lost visceral fat mass showed greater improvements in triglycerides, insulin resistance and maximal fat oxidation.

CONCLUSION

Our data confirms the role of exercise training on improving the inflammatory profile and insulin resistance of OB in the absence of weight loss. However, those who lost a greater amount of visceral fat mass showed greater benefits in terms of insulin profile, triglycerides and maximal fat oxidation.

Oxidative/Antioxidative status in obese and sport trained children: a comparative study

The aim of the study was to compare oxidative/antioxidative status in obese and sport trained children and to correlate obtained redox markers with anthropometrical measurements, body composition parameters, and adipokines levels. 78 (44 males) obese (SG) and 80 (40 males) normal weight sport trained (CG) children matched for age and Tanner stage were recruited for the study. Body composition parameters and basal metabolic rate (BMR) were assessed by bioelectrical impedance analysis (BIA). Oxidative/antioxidative status was evaluated in plasma by total oxidative status (PerOX), oxidized-LDL cholesterol (oxLDL), total antioxidative capacity (ImAnOx), and glutathione peroxidase activity (GPx). Leptin and adiponectin levels and adiponectin/leptin ratio (A/L) were also investigated. OxLDL was higher in SG versus CG (P < 0.05), but ImAnOx and GPx were reduced in SG versus CG (P < 0.01). Redox markers correlated significantly with BMI Z-score, WHR, WHtR, body composition parameters, leptin (in boys only), and A/L ratio (in boys only) in SG and in a whole studied population. PerOX significantly correlated with BMR in the CG. Antioxidative/oxidative status in obese children is significantly impaired and related adipose tissue excess and its hormonal activity. Oxidative status assessed by PerOx is also high in sport trained children but antioxidative defense is significantly more efficient with no overproduction of oxidized LDL.

Cardiovascular complications of type 2 diabetes in youth

The prevalence of type 2 diabetes mellitus (T2DM) in youth has increased dramatically over the past decades. The literature also suggests that the progression from an impaired glucose tolerance state to established T2DM is more rapid in youth, compared to adults. The presence of significant cardiovascular complications in youth with T2DM, including cardiac, macrovascular, and microvascular remodeling, is another major issue in this younger cohort and poses a significant threat to the healthcare system. However, this issue is only now emerging as a major public health concern, with few data to support optimal treatment targets and strategies to reduce cardiovascular disease (CVD) risk in youth with T2DM. Accordingly, the purpose of this minireview is to better understand the cardiovascular complications in youth with T2DM. We briefly describe the pathophysiology from youth studies, including oxidative stress, inflammation, renin-angiotensin aldosterone system, and epigenetics, which link T2DM and CVD. We also describe the literature concerning the early signs of CVD in youth and potential treatment options to reduce cardiovascular risk.

Potential benefits of mindfulness-based interventions in mild cognitive impairment and Alzheimer's disease: an interdisciplinary perspective

The present article is based on the premise that the risk of developing Alzheimer's disease (AD) from its prodromal phase (mild cognitive impairment; MCI) is higher when adverse factors (e.g., stress, depression, and metabolic syndrome) are present and accumulate. Such factors augment the likelihood of hippocampal damage central in MCI/AD aetiology, as well as compensatory mechanisms failure triggering a switch toward neurodegeneration. Because of the devastating consequences of AD, there is a need for early interventions that can delay, perhaps prevent, the transition from MCI to AD. We hypothesize that mindfulness-based interventions (MBI) show promise with regard to this goal. The present review discusses the associations between modifiable adverse factors and MCI/AD decline, MBI's impacts on adverse factors, and the mechanisms that could underlie the benefits of MBI. A schematic model is proposed to illustrate the course of neurodegeneration specific to MCI/AD, as well as the possible preventive mechanisms of MBI. Whereas regulation of glucocorticosteroids, inflammation, and serotonin could mediate MBI's effects on stress and depression, resolution of the metabolic syndrome might happen through a reduction of inflammation and white matter hyperintensities, and normalization of insulin and oxidation. The literature reviewed in this paper suggests that the main reach of MBI over MCI/AD development involves the management of stress, depressive symptoms, and inflammation. Future research must focus on achieving deeper understanding of MBI's mechanisms of action in the context of MCI and AD. This necessitates bridging the gap between neuroscientific subfields and a cross-domain integration between basic and clinical knowledge.

Total antioxidant capacity and oxidative stress after a 10-week dietary intervention program in obese children

Dietary and serum total antioxidant capacity (TAC) are considered appropriate tools for investigating the potential health effects of dietary antioxidants consumed in mixed diets. The aim was to analyze the impact of a dietary intervention on macronutrient intakes and to evaluate the improvement on oxidative status after weight loss (WL) by measuring dietary and serum TAC, and urinary F2-isoprostane levels as markers of oxidative stress. Forty-four overweight/obese children (mean age 11.5 years) were enrolled to undergo a 10-week WL program. They were dichotomized at the median of body mass index-standard deviation score (BMI-SDS) change, as high (HR) and low responders (LR) after intervention. Subjects were prescribed with a fixed full-day meal diet, calculated according to their basal metabolic rate and physical activity levels. A validated food-frequency questionnaire was used to retrospectively calculate TAC and daily nutrient intake. The HR subjects were able to reduce anthropometric indices and to improve lipid and glucose profile. They also significantly diminished fat intake (p = 0.013). Moreover, baseline serum TAC values did significantly predict the reduction in urinary F2 isoprostane (B = -0.236 (-0.393 to -0.078); p = 0.014) in the HR group after the WL program. Notably, changes in dietary TAC after the treatment were associated with a decrease in body weight after the 10-week intervention (B = -2.815 (-5.313 to -0.318), p = 0.029) in the HR group. The -ΔSerumTAC/ΔDietaryTAC and the -ΔF2Isoprostane/ΔDietaryTAC ratios revealed that the relationships between oxidative markers and antioxidants dietary intake were more favorable in the HR than in the LR group.

CONCLUSION

Our study showed that a 10-week WL program was able to reduce adiposity indices in obese children. Moreover, after the intervention changes in dietary TAC and WL were significantly associated. Our result suggests that specific food with a high TAC content (such as fruits, vegetables, and legumes) could be recommended to improve WL.

Antioxidant supplements reduced oxidative stress and stabilized liver function tests but did not reduce inflammation in a randomized controlled trial in obese children and adolescents

Oxidative stress and low-grade systemic inflammation may contribute to the pathogenesis of obesity-induced comorbidities, including nonalcoholic fatty liver disease. Increasing intake of dietary antioxidants might be beneficial, but there are few data in obese children. To examine the effect of antioxidant supplementation on biomarkers of oxidative stress, inflammation, and liver function, we randomly assigned overweight or obese children and adolescents (n = 44; mean ± SD age: 12.7 ± 1.5 y) participating in a lifestyle modification program to a 4-mo intervention with daily antioxidants (vitamin E, 400 IU; vitamin C, 500 mg; selenium, 50 μg) or placebo. We measured anthropometrics, antioxidant status, oxidative stress (F(2)-isoprostanes, F(2)-isoprostane metabolites), inflammation, liver enzymes, fasting insulin and glucose, and lipid profile at baseline and endpoint. There was a significant treatment effect of antioxidant supplementation on antioxidant status [α-tocopherol, β = 23.2 (95% CI: 18.0, 28.4); ascorbic acid, β = 70.6 (95% CI: 51.7, 89.4); selenium, β = 0.07 (95% CI: 0.01, 0.12)] and oxidative stress [8-iso-prostaglandin F2α, β = -0.11 (95% CI: -0.19, -0.02)] but not on any of the inflammatory markers measured. There was a significant treatment effect on alanine aminotransferase [β = -0.13 (95% CI: -0.23, -0.03)], a trend toward a significant effect on aspartate aminotransferase [β = -0.04 (95% CI: -0.09, 0.01)], and no significant effect on γ-glutamyltransferase [β = -0.03 (95% CI: -0.11, 0.06)]. In summary, antioxidant supplementation for 4 mo improved antioxidant-oxidant balance and modestly improved liver function tests; however, it did not reduce markers of systemic inflammation despite significant baseline correlations between oxidative stress and inflammation. The study was registered at clinicaltrials.gov as NCT01316081.

The relationship of oxidative stress, adiposity and metabolic risk factors in healthy Black and White American youth

What is already known about this subject African Americans are disproportionately affected by obesity and other metabolic risk factors in comparison to White Americans. Increasing prevalence of obesity has been associated with concomitant increases in childhood hypertension, dyslipidaemia and type 2 diabetes. Oxidative stress is associated with obesity in both adults and children. What this study adds Oxidative stress is positively associated with total body fat and truncal fat, but not with body mass index (BMI) or BMI z-score in healthy youth. Oxidative stress is associated with diastolic blood pressure in African American but not in White American healthy youth.

BACKGROUND

Oxidative stress is elevated in obese youth, but less is known regarding racial disparities in the relationship of oxidative stress with metabolic risk factors.

OBJECTIVES

To determine the relationship between oxidative stress and metabolic risk factors, adiposity, leptin, adiponectin and cardiovascular fitness (VO2PEAK ) in healthy African American and White American youth.

METHODS

A marker of oxidative stress (F2 -isoprostane), validated markers of metabolic risk factors, fitness and body composition were measured in African American (n = 82) and White American (n = 76) youth (8-17 years old) recruited over a range of BMI percentiles (4th to 99th).

RESULTS

F2 -isoprostane concentration was positively correlated with percentage body fat (r = 0.198) and percentage truncal fat (r = 0.173), but was not different between African American and White American males and females (P = 0.208). African American youth had significantly higher mean systolic and diastolic blood pressure (P = 0.023 and P = 0.011, respectively), body weight, BMI percentile and Tanner stage. After adjusting for gender, age, BMI and Tanner stage, African American youth varied from White Americans in the association of F2 -isoprostane with diastolic blood pressure (P = 0.047), but not with systolic blood pressure, triglycerides, VO2PEAK or homeostatic model assessment for insulin resistance (all P > 0.05).

CONCLUSIONS

Oxidative stress, as measured by urinary F2 -isoprostane concentrations, was positively associated with percent body fat and truncal fat in youth. Oxidative stress levels were similar among African American and White American youth. Among markers of the metabolic syndrome, a significant difference between African American and White American youth was demonstrated only in the association of oxidative stress with diastolic blood pressure.

Is plasma alpha-tocopherol associated with electronegative LDL in obese adolescents?

Obesity has increased in children and adolescents. What is reflected in the early occurrence of cardiometabolic alterations, like hypertension and type 2 diabetes, where the oxLDL formation is stimulated. Various studies have shown that plasma α-tocopherol (α-TP) can protect LDL against oxidation. Nevertheless, the action of plasma α-TP in cardiovascular diseases remains controversial. We conducted a cross-sectional study to evaluate plasma α-TP and its impact on the concentration of LDL(-). Adolescents (n=150) of both sexes were classified into three groups: healthy weight (HW; 50%), overweight (OV; 22%), and obese (OB; 28%). Lipid profile, LDL(-), anti-oxLDL and anti-LDL(-) antibodies, CRP (ELISA) and plasma α-TP (HPLC) were analyzed. Demographic, anthropometric, and food intake data were evaluated. Crude and energy-adjusted intake of vitamin E in the OB group were higher than in the HW group (p<0.001). Crude and energy-adjusted vitamin E intakes were not correlated with plasma α-TP (r=-0.07; p=0.412 and r=-0.064; p=0.467, respectively). Subjects in the OB group had higher TC and LDL-C and lower HDL-C than in the HW and OV groups. C-reactive protein and anti-oxLDL antibodies changed as a function of BMI. The impact of obesity was reinforced by high values for LDL(-) and low content of plasma α-TP in comparison with the HW (p<0.001) and OV groups (p=0.03). This negative profile was maintained for the ratio between α-TP and TC or LDL-C. Plasma α-TP, α-TP/TC and α-TP/LDL-C were negatively associated with LDL(-) and other cardiometabolic risk factors (BMI, WC, AC and anti-oxLDL). Our results demonstrate that obesity in adolescents is associated with high levels of LDL(-) and low plasma α-TP content.

Indices of insulin resistance and dyslipidemia are correlated with lymphocyte proneness to apoptosis in obese or overweight low birth weight children

AIMS

Our aim was to study the relationship between markers of cell proneness to apoptosis and indices of insulin resistance and dyslipidemia in children born with low birth weight (LBW).

METHODS

The study comprised 177 prepubertal children stratified by birth weight and their nutritional status into LBW (n = 138) and normal birth weight (NBW; n = 39) groups. We analyzed DNA from peripheral blood lymphocytes, separated by pulsed-field gel electrophoresis (PFGE), as well as the serum levels of cholesterol, HDL-cholesterol, triglycerides, fasting insulin and glucose, caspase 3, and BCL2.

RESULTS

LBW children with a BMI SDS >1.55 demonstrated increased content of the large fragments of the lymphocyte DNA [300-500 kb (DNA300-500 kb)] in electrophoretic slides (a marker of decreased chromatin stability and susceptibility of cells to apoptosis) compared to the NBW group. In these children the level of DNA300-500 kb exhibited a strong negative correlation with the serum level of antiapoptotic protein of BCL2 (r = -0.901). DNA300-500 kb significantly correlated with calculated indices of insulin resistance: HOMA-IR and QUICKI as well as with the indices of lipid homeostasis (Castelli and AIP).

CONCLUSIONS

Increased susceptibility of lymphocytes to apoptosis correlated with a higher risk of insulin resistance and lipid disturbance in overweight or obese LBW children. A comprehensive study of the proneness of cells to apoptosis should be implemented to further investigate the pathomechanism of the metabolic syndrome in these children.

Oxidative stress and protein carbonylation in adipose tissue - implications for insulin resistance and diabetes mellitus

While historically considered simply as a depot for excess energy, white adipose tissue is a dynamically active endocrine organ capable of responding to a variety of efferent stimuli resulting in the synthesis and secretion of peptides, proteins and metabolites that serve as signal transducers to the peripheral and central circulation. Such regulation controls a variety of physiological processes including energy expenditure, food intake, reproductive capacity and responsiveness to insulin. Indeed, the accumulation of inflammatory cells in white adipose tissue is considered to be causative in the development of insulin resistance and eventually type 2 diabetes mellitus. A large body of evidence suggests that oxidative stress in adipose tissue not only correlates with insulin resistance but is also causative in its development. Moreover, using the available plasma oxidative stress biomarkers, many clinical studies have shown the presence of systemic oxidative stress in obese insulin resistant subjects, and its decrease after the successful treatment of obesity. In this review we emphasize the role of protein carbonylation in dysfunctional obese white adipose tissue and its metabolic implications. We focus on glutathione S-transferase A4 as the key enzyme for trans-4-hydroxy-2-nonenal and trans-4-oxo-2-nonenal removal from the cell, thus preventing protein carbonylation. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.

Rac1 is a possible link between obesity and oxidative stress in Chinese overweight adolescents

Enhanced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity in the monocytes occurred in metabolic syndrome, hypertension, diabetes and obese patients in adults. However, whether NADPH oxidase is involved in the oxidative stress of overweight adolescents without comorbidities is still unclear. This study aimed to identify whether and how NADPH oxidase plays a crucial role in overweight adolescents. The study was performed in 93 overweight adolescents and 31 normal weight controls. Moreover, 87 overweight adolescents were enrolled in weight-loss program. Demographics characteristics, anthropometrics, composition and clinical characteristics were analyzed. Oxidative stress indexes including the levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in plasma and the expression of NADPH oxidase in the monocytes were examined. Overweight adolescents showed a higher oxidative stress state, as indicated by decreased SOD activity and elevated MDA level (P < 0.01). Furthermore, increased NADPH oxidase activity in the monocytes was accompanied by Rac1 upregulation. A significant positive bivariate correlation was found between Rac1 expression and MDA (r = 0.289). There also was a significant positive bivariate correlation between Rac1 expression and obesity-related indexes including BMI (r = 0.227) and percentage of trunk fat (r = 0.233). Data from weight-loss program reinforced the results. Partial correlation analysis indicated that obesity-induced oxidative stress and Rac1 expression is a consequence of aberrant glucose-lipid metabolism in overweight adolescents. In conclusion, we provided novel data showing that NADPH oxidase in the monocytes was highly activated by enhancing Rac1 expression in Chinese overweight adolescents and Rac1 may act as a link between obesity and oxidative stress in overweight adolescents.

Homocysteine and cysteine levels in prepubertal children: association with waist circumference and lipid profile

OBJECTIVE

To evaluate homocysteine and total cysteine levels in prepubertal children and to determine the association between these levels and obesity, increased waist circumference, glucose levels, and lipid profile alterations.

METHODS

Using a cross-sectional study, 677 prepubertal students 6 to 11 y old were assessed. The weight, height, and waist circumference of the students were measured. Laboratory analyses included triacylglycerols, total cholesterol and its fractions, glucose, vitamin B12, folate, homocysteine, and cysteine. Chi-square tests and logistic regression (forward-stepwise) were used for statistical analysis; the significance level was set at 5%.

RESULTS

The median age of the students was 8.9 y (6.5-11.5), and the prevalences of overweight and obesity were 90 in 677 (13.3%) and 81 in 677 (12.0%), respectively. An increase in waist circumference was observed in 180 of 677 children (26.6%). Inadequate levels of low-density lipoprotein cholesterol, triacylglycerols, and high-density lipoprotein cholesterol were found in 95 (14.0%), 129 (19.1%), and 179 (26.4%) of the 677 students, respectively. The median homocysteine and total cysteine plasma levels were 5.6 μmol/L (0.1-11.7) and 365.7 μmol/L (191.5-589.2), respectively. A multivariate analysis showed that children with a waist circumference above the 90th percentile (7.3 μmol/L) were 2.4 times (95% confidence interval 1.4-4.0) more likely to have increased homocysteine levels and that children with increased waist circumferences and those with high low-density lipoprotein cholesterol levels were 2.7 (95% confidence interval 1.6-4.6) and 2.1 (95% confidence interval 1.1-4.0) times more likely, respectively, to have total cysteine levels above the 90th percentile (445.0 μmol/L).

CONCLUSION

The association of abdominal obesity in prepuberty with levels of homocysteine and cysteine found in this study of a prepubertal population could be an early and independent predictor of cardiovascular risk.

A matter of fat: insulin resistance and oxidative stress

BACKGROUND

Obesity is linked to insulin resistance (IR), which can lead to type 2 diabetes mellitus. Oxidative stress present in early obesity may favor the progression to comorbid conditions.

OBJECTIVE

To examine the relationship between oxidative stress biomarkers and the severity of IR in a group of obese children.

METHODS

Forty obese children with a body mass index (BMI) Z-score ≥ 2 were divided into two groups using the median obtained for the homeostasis model assessment of IR (HOMA-IR). Anthropometric parameters (including body fat composition by bioelectrical impedance) and biochemical parameters were assessed. The following biomarkers of oxidative stress were measured: malondialdehyde (MDA), carbonyl groups (CG), reduced glutathione, oxidized low-density lipoprotein, and vitamin E. Comparisons were adjusted for gender and Tanner stage.

RESULTS

Children with high values of HOMA-IR were more likely to have high body fat percentage and waist circumferences. However, the BMI Z-score did not correlate to the level of IR. Children with higher values of HOMA-IR presented increased levels of markers of oxidative stress in lipids (MDA, p = 0.005) and proteins (CG, p = 0.015). Moreover, MDA increased with increasing levels of HOMA-IR (r = 0.50, p = 0.002), suggesting that lipoperoxidation increases as IR worsens. In a multivariate regression model, only HOMA-IR was predictive of MDA values, irrespective of adiposity parameters and other metabolic risk factors (r2 = 0.22, p = 0.002).

CONCLUSIONS

Oxidative stress increases in obese children according to the severity of IR, which could be linked to the development of comorbidities.

Endothelial dysfunction, inflammation, and oxidative stress in obese children and adolescents: markers and effect of lifestyle intervention

With an increasing prevalence, pediatric obesity is often a prelude to adulthood obesity, and represents a major public health issue. Comorbidities are very common and severe in obese adults, justifying the search for earlier markers or risk factors for cardiovascular diseases in obese children. Endothelial dysfunction has been found to be present in the early stages of atherosclerosis, and can be non-invasively assessed with widely accepted and well-standardized techniques at the macrocirculation level. Endothelial dysfunction at the microcirculation level is less documented in obese children. Obesity in children has been repeatedly and independently correlated to endothelial dysfunction, inflammation and oxidative stress markers, although the relationship between these factors remains to be investigated. However, this would not only allow substantial improvements in risk stratification, but also provide essential data regarding the evolution of endothelial dysfunction in childhood obesity, especially during puberty when pro-inflammatory and pro-oxidative changes, with relative insulin resistance, occur. Therapeutic strategies such as lifestyle interventions in early childhood obesity appear all the more necessary, optimally including both exercise and diet because of their known effects on inflammatory and oxidative stress markers, potentially reversing endothelial dysfunction.

Elevated advanced oxidation protein products (AOPPs) indicate metabolic risk in severely obese children

BACKGROUND AND AIMS

The assessment of oxidative stress may aid in the identification of subsequent metabolic risk in obese children. The objective of this study was to determine whether the plasma level of advanced oxidation protein products, analyzed with a recently proposed modified assay that involves a delipidation step (mAOPPs), was related to metabolic risk factors (MRFs) in severely obese children.

METHODS AND RESULTS

The plasma levels of mAOPPs were determined by spectrophotometry in 54 severely obese and 44 healthy children. We also measured lipid peroxidation biomarkers (thiobarbituric acid-reactive substances, malondialdehyde, and 8-isoprotane F(2α)) and sulfhydryl groups, a marker of antioxidant defense. Protein oxidation and lipid peroxidation markers were higher and sulfhydryl levels were lower in obese children compared with controls. Taking metabolic risk into account, obese children were subdivided according to the cutoff point (53.2 μmol/L) obtained for their mAOPPs values from the ROC curve. Anthropometric measures and the existence of hypertension did not differ between groups. The presence of dyslipidemia and insulin resistance was significantly higher in the group with higher mAOPPs levels. The highest levels of mAOPPs were found in the children with ≥3 MRFs. The level of mAOPPs was positively correlated with triglycerides and negatively correlated with high-density lipoprotein cholesterol. There was no correlation of this marker of protein oxidation with biomarkers of lipid peroxidation.

CONCLUSION

The determination of mAOPPs in delipidated plasma is an easy way to evaluate protein oxidation. It may be useful in severely obese children for better cardiovascular risk assessment.

Predominant role of obesity/insulin resistance in oxidative stress development

BACKGROUND

  Hyperlipidaemia, hyperglycaemia and hyperinsulinaemia, hallmarks of the postprandial state, have been also associated with increased oxidative stress and lipoprotein oxidation contributing to vascular injury and atherosclerosis. However, the specific links among metabolic disorders, postprandial state, insulin resistance and oxidative stress are still to be clarified. This study aimed at investigating the individual role played by obesity, insulin resistance and type 2 diabetes in the occurrence of fasting and postprandial oxidative stress.

DESIGN

Biomarkers of oxidative stress [F2-isoprostanes and circulating oxidized low-density lipoproteins (LDL)], LDL oxidability (conjugated diene kinetic, thiobarbituric acid reactive substances (TBARs) formation and electronegativity increase) and antioxidant vitamins (β-carotene, α-tocopherol and retinol) were evaluated at fasting and 6 h after a standard fat-rich meal in 10 obese diabetic (ObD), 11 obese and 11 normal-weight control men. Insulin sensitivity was evaluated by euglycaemic hyperinsulinaemic clamp.

RESULTS

ObD and obese subjects, characterized by a similar level of adiposity and insulin resistance, showed higher urinary F2-isoprostanes and circulating oxidized LDL, an increased susceptibility to oxidation of plasma LDL (lower lag phase, higher TBARs formation, and higher relative electrophoretic mobility), and lower plasma content of β-carotene and retinol than control subjects, both at fasting and after the test meal.

CONCLUSIONS

Obesity and insulin resistance, more than type 2 diabetes, play the most relevant role in oxidative stress development. The correction of obesity and insulin resistance might be a useful strategy in counteracting systemic oxidative stress.

Oxidant mechanisms in childhood obesity: the link between inflammation and oxidative stress

Evidence of obesity-induced oxidative stress in adults has emerged in the past several years, and similar evidence has been demonstrated in children more recently. The reactive species of oxygen or nitrogen can chemically alter all major classes of biomolecules by modifying their structure and function. Organisms have developed mechanisms to protect biomolecules from the deleterious effects of free radicals. These include the enzymes superoxide dismutase, catalase, and glutathione peroxidase, as well as water and lipid-soluble antioxidants, such as glutathione, ascorbate (vitamin C), α-tocopherol (vitamin E), and β-carotene. Obesity creates oxidant conditions that favor the development of comorbid diseases. Energy imbalances lead to the storage of excess energy in adipocytes, resulting in both hypertrophy and hyperplasia. These processes are associated with abnormalities of adipocyte function, particularly mitochondrial stress and disrupted endoplasmic reticulum function. In this sense, oxidative stress can also be induced by adipocyte associated inflammatory macrophages. There is a close link among obesity, a state of chronic low-level inflammation, and oxidative stress. In addition, the dysregulation of adipocytokines, which are secreted by adipose tissue and promoted by oxidative stress, act synergistically in obesity-related metabolic abnormalities. Adipocytokines link the local and systemic inflammation responses in the context of obesity. It is thought that the evaluation of oxidative status may allow for the identification of patients at an increased risk of complications. Decreasing the levels of chronic inflammation and oxidative stress in childhood may decrease cardiovascular morbidity and mortality in adulthood.

Oxidative markers in children with severe obesity following low-calorie diets supplemented with mandarin juice

AIM

 To evaluate the effect of supplementing a hypocaloric diet with mandarin juice, a food with a high content of antioxidants (vitamin C, flavonoids and carotenoids), on biomarkers of oxidant/antioxidant status of severe obese children.

METHODS

 Forty obese children were randomized into two groups pair-wise in a 4-week controlled intervention study. Both groups followed a hypocaloric diet. One group received additionally a supplementation of 500mL of 100% mandarin juice daily. Clinical data, anthropometry, dietary intake and fasting blood samples were collected at baseline and after the intervention. Lipid peroxidation was assessed by circulating levels of malondialdehyde, and protein oxidation was determined by the concentration of plasma carbonyl groups. The antioxidant defence was evaluated by red cell-reduced glutathione and plasma levels of α-tocopherol and vitamin C.

RESULTS

 The supplemented group experienced a decrease in the levels of malondialdehyde (-9.6%, p =0.014) and carbonyl groups (-36.1%, p =0.006) and an increase in antioxidants (α-tocopherol +16.1%, p=0.006, glutathione +36.1%, p < 0.0001, and vitamin C + 94.6%, p < 0.0001).

CONCLUSION

  The mandarin juice consumption with a reduced calorie diet positively affects the antioxidant defence and produces a decrease in biomarkers of oxidative stress in obese children.