Characteristics of reactive oxygen metabolites in serum of early teenagers in Japan

Exercise-Induced Oxidative Stress Responses in the Pediatric Population

Adults demonstrate an upregulation of their pro- and anti-oxidant mechanisms in response to acute exercise while systematic exercise training enhances their antioxidant capacity, thereby leading to a reduced generation of free radicals both at rest and in response to exercise stress. However, less information exists regarding oxidative stress responses and the underlying mechanisms in the pediatric population. Evidence suggests that exercise-induced redox perturbations may be valuable in order to monitor exercise-induced inflammatory responses and as such training overload in children and adolescents as well as monitor optimal growth and development. The purpose of this review was to provide an update on oxidative stress responses to acute and chronic exercise in youth. It has been documented that acute exercise induces age-specific transient alterations in both oxidant and antioxidant markers in children and adolescents. However, these responses seem to be affected by factors such as training phase, training load, fitness level, mode of exercise etc. In relation to chronic adaptation, the role of training on oxidative stress adaptation has not been adequately investigated. The two studies performed so far indicate that children and adolescents exhibit positive adaptations of their antioxidant system, as adults do. More studies are needed in order to shed light on oxidative stress and antioxidant responses, following acute exercise and training adaptations in youth. Available evidence suggests that small amounts of oxidative stress may be necessary for growth whereas the transition to adolescence from childhood may promote maturation of pro- and anti-oxidant mechanisms. Available evidence also suggests that obesity may negatively affect basal and exercise-related antioxidant responses in the peripubertal period during pre- and early-puberty.

Prenatal phthalate exposure and 8-isoprostane among Mexican-American children with high prevalence of obesity

Oxidative stress has been linked to many obesity-related conditions among children including cardiovascular disease, diabetes mellitus and hypertension. Exposure to environmental chemicals such as phthalates, ubiquitously found in humans, may also generate reactive oxygen species and subsequent oxidative stress. We examined longitudinal changes of 8-isoprostane urinary concentrations, a validated biomarker of oxidative stress, and associations with maternal prenatal urinary concentrations of phthalate metabolites for 258 children at 5, 9 and 14 years of age participating in a birth cohort residing in an agricultural area in California. Phthalates are endocrine disruptors, and in utero exposure has been also linked to altered lipid metabolism, as well as adverse birth and neurodevelopmental outcomes. We found that median creatinine-corrected 8-isoprostane concentrations remained constant across all age groups and did not differ by sex. Total cholesterol, systolic and diastolic blood pressure were positively associated with 8-isoprostane in 14-year-old children. No associations were observed between 8-isoprostane and body mass index (BMI), BMI Z-score or waist circumference at any age. Concentrations of three metabolites of high molecular weight phthalates measured at 13 weeks of gestation (monobenzyl, monocarboxyoctyl and monocarboxynonyl phthalates) were negatively associated with 8-isoprostane concentrations among 9-year olds. However, at 14 years of age, isoprostane concentrations were positively associated with two other metabolites (mono(2-ethylhexyl) and mono(2-ethyl-5-carboxypentyl) phthalates) measured in early pregnancy. Longitudinal data on 8-isoprostane in this pediatric population with a high prevalence of obesity provides new insight on certain potential cardiometabolic risks of prenatal exposure to phthalates.

Increased oxidative stress in patients with severe disability: Association with nutrition

BACKGROUND

Previous studies have described a role of oxidative stress in the pathogenesis of various pediatric disorders, but investigation into oxidative stress status in patients with severe disability remains limited. The aim of the present study was therefore to clarify the oxidative stress status in patients with severe disability, focusing specifically on intake of three major nutrients and micronutrients with antioxidant activities.

METHODS

Thirty-one patients with severe disability (mean age, 14.1 ± 7.8 years) were enrolled. Three in vivo biomarkers, plasma biological antioxidant potential (BAP), plasma reactive oxygen metabolite-derived compounds (d-ROM), and urinary 8-hydroxydeoxyguanosine (8-OHdG), were determined for evaluating oxidative status. The dietary intake of three major nutrients and various micronutrients was estimated from dietary records over a 3 day period.

RESULTS

In patients with severe disability, BAP was significantly lower and d-ROM and 8-OHdG significantly higher than in historical controls. Among these markers, a significant positive correlation was found in BAP versus d-ROM and d-ROM versus 8-OHdG. On multiple regression analysis, a significant inverse association between 8-OHdG and carotenoid intake was seen.

CONCLUSION

The oxidative/antioxidative balance shifts towards oxidative status dominance in patients with severe disability. More research is needed on nutritional intake of antioxidative nutrients to determine whether they can be used to reduce oxidative stress.

Antioxidation improves in puberty in normal weight and obese boys, in positive association with exercise-stimulated growth hormone secretion

BACKGROUND

Oxidative stress is associated with obesity while the evidence for the role of GH in pro- and antioxidation is inconclusive. This study investigates the relationships between growth hormone (GH), pro- and antioxidation in relation to obesity and puberty before and after an acute bout of exercise.

METHODS

In this case-control study, 76 healthy normal-weight and obese, prepubertal and pubertal boys underwent a blood sampling before and immediately after an aerobic exercise bout until exhaustion at 70% maximal oxygen consumption. Markers of prooxidation (thiobarbituric acid reactive substances (TBARS) and protein carbonyls (PCs)) and antioxidation (glutathione (GSH), oxidized glutathione disulfide (GSSG), GSH/GSSG ratio, glutathione peroxidase (GPX), catalase, and total antioxidant capacity (TAC)) and hormones (GH, insulin-like growth factor (IGF)-1, IGF-BP-3, luteinizing hormone, follicle-stimulating hormone, and testosterone) were measured.

RESULTS

Baseline and postexercise TBARS and PCs were greater, while baseline GSH, GSH/GSSG ratio, GPX, and TAC were lower in obese than that in normal-weight participants. In all participants, waist was the best negative and positive predictor for postexercise GPX and TBARS, respectively. Baseline TAC was greater in pubertal than that in pre-pubertal participants. In all participants, baseline GH was the best negative predictor for postexercise PCs. Significant positive linear correlation exists between the exercise-associated GH, and GSSG increases in pubertal normal-weight boys.

CONCLUSIONS

Higher prooxidation and lower antioxidation were observed in obese boys, while antioxidation improves with puberty and postexercise, paralleling GH accentuated secretion.

Age-related responses in circulating markers of redox status in healthy adolescents and adults during the course of a training macrocycle

Redox status changes during an annual training cycle in young and adult track and field athletes and possible differences between the two age groups were assessed. Forty-six individuals (24 children and 22 adults) were assigned to four groups: trained adolescents, (TAD, N = 13), untrained adolescents (UAD, N = 11), trained adults (TA, N = 12), and untrained adults (UA, N = 10). Aerobic capacity and redox status related variables [total antioxidant capacity (TAC), glutathione (GSH), catalase activity, TBARS, protein carbonyls (PC), uric acid, and bilirubin] were assessed at rest and in response to a time-trial bout before training, at mid- and posttraining. TAC, catalase activity, TBARS, PC, uric acid, and bilirubin increased and GSH declined in all groups in response to acute exercise independent of training status and age. Training improved aerobic capacity, TAC, and GSH at rest and in response to exercise. Age affected basal and exercise-induced responses since adults demonstrated a greater TAC and GSH levels at rest and a greater rise of TBARS, protein carbonyls, and TAC and decline of GSH in response to exercise. Catalase activity, uric acid, and bilirubin responses were comparable among groups. These results suggest that acute exercise, age, and training modulate the antioxidant reserves of the body.

Relationship between obesity and serum reactive oxygen metabolites in adolescents

OBJECTIVES

Various cross-sectional studies have revealed a significant positive relationship between systemic oxidative stress and obesity-related indices such as body mass index (BMI, kg/m²). However, little is known of the role of oxidative stress during adolescence. The aim of this study was to determine the association between obesity and serum reactive oxygen metabolites (ROM) in adolescents.

METHOD

A total of 595 healthy junior high school students from northern Japan were enrolled in the study. Oxidative stress was evaluated by measuring serum levels of ROM. Obesity indices included BMI and percentage body fat (PBF). The analyses were stratified by sex and controlled for age and menarche. Partial correlation coefficients and analysis of covariance were also analyzed.

RESULTS

In female students, ROM levels increased with increasing BMI and PBF. Therefore, ROM levels were significantly higher in the underweight group than in the BMI-classified overweight-obese (P < 0.001) and normal weight groups (P < 0.05). ROM levels were significantly higher in the high PBF group than in the underweight (P < 0.05) and normal groups (P < 0.001).

CONCLUSION

The results of this study show that, regardless of menarche, obesity indicators such as BMI and PBF are correlated with the level of oxidative stress in female adolescents.