Sandra M. Villares

Diet and exercise training restore blood pressure and vasodilatory responses during physiological maneuvers in obese children

Background—The effects of diet and diet plus exercise training on muscle vasodilatation during physiological maneuvers in obese children are unknown. We tested the hypothesis that (1) blood pressure (BP) and forearm vascular conductance (FVC) responses during handgrip exercise and mental stress would be altered in obese children and (2) diet plus exercise training would restore BP and FVC responses during exercise and mental stress in obese children. Methods and Results—Thirty-nine obese children (aged 10±0.2 years) were randomly divided into 2 groups: diet plus exercise training (n=21; body mass index [BMI]=28±0.5 kg/m2) and diet (n=18; BMI=30±0.4 kg/m2). Ten age-matched lean control children (BMI=17±0.5 kg/m2) were also studied. Forearm blood flow was measured by venous occlusion plethysmography. BP was monitored noninvasively. Handgrip exercise was performed at 30% maximal voluntary contraction for 3 minutes. Stroop color word test was performed for 4 minutes. Baseline BP was significantly higher and FVC was significantly lower in obese children. During exercise and mental stress, BP responses were significantly higher and FVC responses were significantly lower in obese children. Diet and diet plus exercise training significantly reduced body weight. Diet and diet plus exercise training significantly decreased BP levels during exercise and mental stress. Diet plus exercise training, in contrast to diet alone, significantly increased FVC responses during exercise (3.7±0.3 versus 5.6±0.4 U; P=0.01) and mental stress (3.5±0.5 versus 4.5±0.4 U; P=0.02). After diet plus exercise training, BP and FVC responses during exercise and mental stress were similar between obese children and the control group. Conclusions—Obesity exacerbates BP responses and impairs FVC responses during exercise and mental stress in children. Diet and exercise training restore BP and FVC responses in obese children.

Musculoskeletal findings in obese children

Aim:  A cross‐sectional study was conducted to explore osteoarticular alterations in obese children.

Muscle sympathetic nerve activity and hemodynamic alterations in middle-aged obese women

To study the relationship between the sympathetic nerve activity and hemodynamic alterations in obesity, we simultaneously measured muscle sympathetic nerve activity (MSNA), blood pressure, and forearm blood flow (FBF) in obese and lean individuals. Fifteen normotensive obese women (BMI = 32.5 +/- 0.5 kg/m2) and 11 age-matched normotensive lean women (BMI = 22.7 +/- 1.0 kg/m2) were studied. MSNA was evaluated directly from the peroneal nerve by microneurography, FBF was measured by venous occlusion plethysmography, and blood pressure was measured noninvasively by an autonomic blood pressure cuff. MSNA was significantly increased in obese women when compared with lean control women. Forearm vascular resistance and blood pressure were significantly higher in obese women than in lean women. FBF was significantly lower in obese women. BMI was directly and significantly correlated with MSNA, blood pressure, and forearm vascular resistance levels, but inversely and significantly correlated with FBF levels. Obesity increases sympathetic nerve activity and muscle vascular resistance, and reduces muscle blood flow. These alterations, taken together, may explain the higher blood pressure levels in obese women when compared with lean age-matched women.

Effect of gastric bypass on spontaneous growth hormone and ghrelin release profiles.

Objective: The purpose of this study was to analyze growth hormone (GH) concentrations in obese women before and after Roux‐en‐Y gastric bypass (RYGBP) and how resulting changes in weight, fat mass, ghrelin levels, and insulin sensitivity affect GH secretion.

Genetic variants influencing effectiveness of weight loss strategies

Body weight excess has an increasingly high prevalence in the world. Obesity is a complex disease of multifactorial origin with a polygenic condition affected by environmental factors. Weight loss is a primary strategy to treat obesity and its morbidities. Weight changes through life depend on the interaction of environmental, behavioral and genetic factors. Interindividual variation of weight loss in response to different types of interventions (behavioral, caloric restriction, exercise, drug or surgery) has been observed. In this article, currently available data on the role of candidate gene polymorphisms in weight loss are reviewed. Even though control of weight loss by genotype was described in twin and family studies, it is premature to recommend use of genotyping in the design of therapeutic diets or drug treatment. Future studies will have to be large in order to assess the effects of multiple polymorphisms, and will have to control factors other than diet.

Body weight, metabolism and clock genes

Biological rhythms are present in the lives of almost all organisms ranging from plants to more evolved creatures. These oscillations allow the anticipation of many physiological and behavioral mechanisms thus enabling coordination of rhythms in a timely manner, adaption to environmental changes and more efficient organization of the cellular processes responsible for survival of both the individual and the species. Many components of energy homeostasis exhibit circadian rhythms, which are regulated by central (suprachiasmatic nucleus) and peripheral (located in other tissues) circadian clocks. Adipocyte plays an important role in the regulation of energy homeostasis, the signaling of satiety and cellular differentiation and proliferation. Also, the adipocyte circadian clock is probably involved in the control of many of these functions. Thus, circadian clocks are implicated in the control of energy balance, feeding behavior and consequently in the regulation of body weight. In this regard, alterations in clock genes and rhythms can interfere with the complex mechanism of metabolic and hormonal anticipation, contributing to multifactorial diseases such as obesity and diabetes. The aim of this review was to define circadian clocks by describing their functioning and role in the whole body and in adipocyte metabolism, as well as their influence on body weight control and the development of obesity.

Effects of diet and exercise training on neurovascular control during mental stress in obese women

Since neurovascular control is altered in obese subjects, we hypothesized that weight loss by diet (D) or diet plus exercise training (D + ET) would improve neurovascular control during mental stress in obese women. In a study with a dietary reduction of 600 kcal/day with or without exercise training for 4 months, 53 obese women were subdivided in D (N = 22, 33 +/- 1 years, BMI 34 +/- 1 kg/m2), D + ET (N = 22, 33 +/- 1 years, BMI 33 +/- 1 kg/m2), and nonadherent (NA, N = 9, 35 +/- 2 years, BMI 33 +/- 1 kg/m2) groups. Muscle sympathetic nerve activity (MSNA) was measured by microneurography and forearm blood flow by venous occlusion plethysmography. Mental stress was elicited by a 3-min Stroop color word test. Weight loss was similar between D and D + ET groups (87 +/- 2 vs 79 +/- 2 and 85 +/- 2 vs 76 +/- 2 kg, respectively, P < 0.05) with a significant reduction in MSNA during mental stress (58 +/- 2 vs 50 +/- 2, P = 0.0001, and 59 +/- 3 vs 50 +/- 2 bursts/100 beats, P = 0.0001, respectively), although the magnitude of the response was unchanged. Forearm vascular conductance during mental stress was significantly increased only in D + ET (2.74 +/- 0.22 vs 3.52 +/- 0.19 units, P = 0.02). Weight loss reduces MSNA during mental stress in obese women. The increase in forearm vascular conductance after weight loss provides convincing evidence for D + ET interventions as a nonpharmacologic therapy of human obesity.

Allelic variations in the vitamin D receptor gene, insulin secretion and parents' heights are independently associated with height in obese children and adolescents

Polymorphisms in the VDR gene were reported to be associated with variations in intrauterine and postnatal growth and with adult height, but also with other traits that are strongly correlated such as the BMI, insulin sensitivity, insulin secretion and hyperglycemia. Here, we assessed the impact of VDR polymorphisms on body height and its interactions with obesity- and glucose tolerance-related traits in obese children and adolescents. We studied 173 prepubertal (Tanners stage 1) and 146 pubertal (Tanners stages 2-5) obese children who were referred for a weight-loss program. Three single nucleotide polymorphisms were genotyped: rs1544410 (BsmI), rs7975232 (ApaI) and rs731236 (TaqI). BsmI and TaqI genotypes were significantly associated with height in pubertal children, but the associations did not reach statistical significance in prepubertal children. In stepwise regression analyses, the lean body mass, insulin secretion, BsmI or TaqI genotypes and the fathers and the mothers height were independently and positively associated with height in pubertal children. These covariables accounted for 46% of the trait variance. The height of homozygous carriers of the minor allele of BsmI was 0.65 z-scores (4cm) higher than the height of homozygous carriers of the major allele (P=.0006). Haplotype analyses confirmed the associations of the minor alleles of BsmI and TaqI with increased height. In conclusion, VDR genotypes were significantly associated with height in pubertal obese children. The associations were independent from the effects of confounding traits, such as the body fat mass, insulin secretion, insulin sensitivity and glucose tolerance.

Angiotensin converting enzyme insertion/deletion polymorphism is associated with increased adiposity and blood pressure in obese children and adolescents

BACKGROUND The insertion/deletion polymorphism in the gene encoding the angiotensin-converting enzyme (ACE I/D) was associated with arterial hypertension and obesity in adults, but the data in children are scarce and yielded contrasting results. We assessed the impact of the ACE I/D on blood pressure and obesity related traits in a Brazilian cohort of obese children and adolescents. METHODS AND RESULTS ACE I/D was genotyped in 320 obese children and adolescents (64% of girls) aged 7-16years, referred for a weight-loss program. We observed an association of the D-allele with blood pressure and with pre-hypertension/hypertension in boys (odds ratio 2.44, 95% C.I. 1.34-4.68, p=0.005 for a codominant model). The D-allele, insulin resistance and body fat mass had independent and additive effects and explained 14% of the variance of pre-hypertension/hypertension. The BMI, waist circumference, and body fat mass were significantly higher in DD/ID boys than in II boys (p<0.005). Allelic associations with obesity related traits were independent of the association with blood pressure. No genotype associations were observed in girls. CONCLUSIONS The D-allele of the ACE I/D polymorphism was associated with arterial hypertension and with obesity related traits in boys, but not in girls, in a cohort of obese children and adolescents. These associations were independent of each other, as well as of the effects of other confounding traits such as insulin secretion, insulin sensitivity and glucose tolerance. Our results are in agreement with experimental evidences suggesting that the renin-angiotensin system plays a role in the regulation of visceral adipose tissue accumulation.

Binge eating symptoms, diet composition and metabolic characteristics of obese children and adolescents.

This study aimed to determine the occurrence of symptoms of binge eating (BE) among children and adolescents seeking treatment for their obesity, as well as to evaluate their diet composition and metabolic characteristics. The Binge Eating Scale (BES) was answered by 128 children and adolescents (10.77+/-2.04 years, BMI 29.15+/-4.98 kg/m2, BMI Z score 2.28+/-0.46, 53.91% pubescent), who were classified into two subgroups--binge eaters (score greater than or equal to 18 points) and non-binge eaters (score lower than 18 points). Anthropometric data, body composition and Tanner stages were collected and dietary evaluation conducted. Blood pressure was determined, and glucose, lipid profile and insulin assays were performed. Insulin resistance was determined using HOMA-IR. BE symptoms were present in 39.06% of patients. Carbohydrate intake in diet composition was significantly higher among binge eaters. Children with BE did not demonstrate significant dissimilar metabolic characteristics when compared to their counterparts without BE. Therefore, BE seems to be a prevalent problem among children and adolescents seeking help for their obesity. When associated with obesity, this eating behaviour can influence macronutrient consumption through increased carbohydrate intake. Further research would be valuable to verify the reproducibility of these findings.