Prevention of unhealthy weight in children by promoting physical activity using a socio-ecological approach: what can we learn from intervention studies?

AIM: Our objectives was to identify the characteristics of interventions likely to successfully prevent overweight in youngsters by promoting physical activity (PA), with special focus on dimensions of the socio-ecological model of behaviour and health, and unresolved issues. METHODS: This was a systematic review of population-based interventions either promoting PA or limiting sedentary behaviour in children with measure of weight status as an endpoint. The efficacy of studies was evaluated according to the levels of PA determinants in the socio-ecological model (individual, interpersonal, institutional environment, community) targeted by the interventions. RESULTS: A total of 54 studies met our inclusion criteria, most of them published within the last 5 years and targeting children aged 6-12 years. Twenty-three interventions targeted individual and/or interpersonal PA determinants only; 26 targeted determinants at three or four levels with at least one environment component at the institutional level; and five were multilevel community-based interventions. Our review indicated that programmes targeting PA determinants at the different levels of the socio-ecological model, including the social and organizational/built environments, had the greatest potential for preventing obesity in youngsters. Targeting various facets of PA, including everyday PA, might represent another key element for program efficacy on weight status. CONCLUSION: Data regarding the efficacy of comprehensive PA interventions that simultaneously address individual attitudes and skills, the social context, and the environment, to prevent overweight in children are encouraging. Further studies are needed to evaluate the maintenance of the effects and whether such strategies apply to young children and older adolescents, and to different cultural contexts.

A socio-ecological approach promoting physical activity and limiting sedentary behavior in adolescence showed weight benefits maintained 2.5 years after intervention cessation.

BACKGROUND: Obesity in youth remains a major public health issue. Yet no effective long-term preventive strategy exists. We previously showed that a school-based socio-ecological approach targeting behavior and social/environmental influences on physical activity (PA) prevented 4-year excessive weight gain in 12-year olds. In this study, we investigated if this efficacy persists 30 months after intervention cessation. METHODS AND FINDINGS: The program targeted students, family, school and the living environment to promote/support PA and prevent sedentary behavior (SB). A total of 732 students from eight randomized middle schools completed the 4-year trial. At the 30-month post-trial follow-up, body mass index (BMI), fat mass index (FMI), leisure PA (LPA), home/school/workplace active commuting, TV/video time (TVT), and attitudes toward PA were measured in 531 adolescents. The beneficial effects of the intervention on the excess BMI increase (+0.01 vs +0.34 kg m(-2) in the intervention and control groups, respectively) and on the overweight incidence in initially non-overweight students (4.3% vs 8.6%; odds ratio=0.48 (95% confidence interval: 0.23-1.01)) were maintained at the post-trial follow-up. LPA was not maintained at the level achieved during the trial. However, we still observed a prevention of the age-related decrease of the adolescents' percentage reporting regular LPA (-14.4% vs -26.5%) and a higher intention to exercise in the intervention group. The intervention promoted lower TVT (-14.0 vs +13.6 min per day) and higher active commuting changes (+11.7% vs -4.8%). Trends in higher BMI reduction in students with high initial TVT and in the least wealthy group were noted. TVT changes throughout the follow-up predicted excess BMI and FMI changes. CONCLUSIONS: Long-term multilevel approach targeting PA and SB prevents excessive weight gain up to 30 months after intervention cessation. The efficacy may be higher in the most sedentary and least wealthy adolescents. Healthy PA-related behavior inducing long-lasting weight effects can be promoted in youth providing that an ecological approach is introduced in the prevention strategy.

[Effect of coronary risk and of hypertension on renal risk in the general population]. / Impact du risque coronarien et de l'hypertension sur le risque rénal en population générale.

INTRODUCTION: Abnormal albuminuria (≥ 30 mg/g) and low estimated glomerular filtration rate (eGFR<60 mL/min/1.73 m(2)) not only are renal risk factors, but also cardiovascular and coronarian risk factors. Though, the relation between coronary risk and renal risk, and its interaction with insufficiently controlled brachial pressure (BP) is poorly described in the literature. SUBJECTS AND METHODS: We realised a cross-sectional study on subjects 40 and older, having attended a medical exam in 11 IRSA centers between 2006 and 2010. Every subject filled a questionnaire, underwent biological analysis, and a clinical examination. eGFR and albuminuria were measured, and the 10-year risk of coronarian event was calculated (Laurier's equation) RESULTS: We analysed 118,314 subjects, amongst whom 96,400 had no personal cardiovascular history. Amongst those, 9.1% had a 10-year coronary risk over 10%. There was a continuous relationship between coronary risk and renal risk: subjects with a risk above 15% had a significative risk of pathological albuminuria (OR: 6.87 [5.58-8.44]), and of low eGFR (2.26 [1.82-2.78]) compared to those with a risk under 5%. There was a continuous relationship between BP and renal risk, with a significative risk of pathological albuminuria (OR=7.75 [6.69-8.96]) and of low eGFR (OR: 1.33 [1.09-1.60]) in subjects with BP greater than or equal to 180/110 mmHg, compared to those with normal BP. CONCLUSION: In the French population, 9.1% of subjects have a 10-year coronary risk above 10%. This risk is associated to abnormalities of the renal function. The relation between coronary risk and renal risk is continuous and dose-dependent, as is the relation between BP and renal risk.

Relevance of increased serum cystatin C to vascular alterations in obese children.

OBJECTIVE: Epidemiological studies report a positive relationship between serum cystatin C and cardiovascular outcomes in adults. Here, we tested the relevance of cystatin C as a biomarker for early vascular alterations in severely obese children. METHODS: Two hundred nineteen obese (140 girls; age = 11.7 ± 2.7 years, BMI Z-score = 4.7 ± 1.2 SD) and 262 non-obese children (129 girls; age = 11.6 ± 0.6 years, body mass index [BMI] Z-score = 0.1 ± 1.0 SD). Serum cystatin C was measured by immunonephelometry. Intima media thickness (IMT), incremental elastic modulus, and flow-mediated and glyceryl-trinitrate-mediated dilations were determined at the common carotid artery and the brachial artery in obese children. RESULTS: Obese children had significantly higher serum cystatin C than normal weight controls (0.86 ± 0.01 vs. 0.80 ± 0.01, P < 0.0001). In obese children, serum cystatin C correlates positively with BMI and the homeostasis model assessment index and negatively with the quantitative insulin sensitivity check index and adiponectin. A positive relationship was found between serum cystatin C and carotid IMT (r = 0.23, P = 0.0005), which remained significant in multivariate models adjusted for BMI (P = 0.01) and adiponectin with a trend towards significance (P = 0.05). CONCLUSION: This study positions cystatin C and adiponectin as covariables associated with arterial wall thickness in obese children. Although the underlying pathophysiology linking cystatin C to early vascular disease remains to be deciphered, cystatin C may represent a novel adipose tissue-derived biomarker implicated in obesity-related comorbidities early in life.

Successful overweight prevention in adolescents by increasing physical activity: a 4-year randomized controlled intervention.

BACKGROUND: Population-based studies directed at promoting physical activity in youth have shown limited success in obesity prevention. OBJECTIVE: To assess whether an intervention integrating environmental changes to induce sustained changes in physical activity, prevents overweight in adolescents. DESIGN: Four-year randomized trial started in 2002 in eight middle schools of Eastern France. The intervention, randomized at school level, was designed to promote physical activity by changing attitudes through debates and attractive activities, and by providing social support and environmental changes encouraging physical activity. SUBJECTS: Nine hundred and fifty four 12-year-old six-graders. MEASUREMENTS: Body mass index (BMI), body composition, physical activity by questionnaire, plasma lipids and glucose, insulin resistance. RESULTS: Intervention students had a lower increase in BMI (P=0.01) and age- and gender-adjusted BMI (P<0.02) over time than controls. The differences across groups of the age- and gender-adjusted BMI changes (95% confidence interval (CI)) were -0.29 (-0.51; -0.07) kg/m2 at 3 years, -0.25 (-0.51; 0.01) kg/m2 at 4 years. An interaction with baseline weight status was noted. The intervention had a significant effect throughout the study in initially non-overweight adolescents (-0.36 (-0.60;-0.11) kg/m2 for adjusted BMI at 4 years), corresponding to a lower increase in fat mass index (P<0.001). In initially overweight adolescents, the differences observed across groups at 2 years (-0.40 (-0.94; 0.13) kg/m2 for adjusted BMI) did not persist over time. At 4 years, 4.2% of the initially non-overweight adolescents were overweight in the intervention schools, 9.8% in the controls (odds ratio=0.41 (0.22; 0.75); P<0.01). Independent of initial weight status, compared with controls, intervention adolescents had an increase in supervised physical activity (P<0.0001), a decrease of TV/video viewing (P<0.01) and an increase of high-density cholesterol concentrations (P<0.0001). CONCLUSION: Enhancing physical activity with a multilevel program prevents excessive weight gain in non-overweight adolescents. Our study provides evidence that prevention of obesity in youth is feasible.

The maternal diet during pregnancy programs altered expression of the glucocorticoid receptor and type 2 11beta-hydroxysteroid dehydrogenase: potential molecular mechanisms underlying the programming of hypertension in utero.

Potential mechanisms underlying prenatal programming of hypertension in adult life were investigated using a rat model in which maternal protein intake was restricted to 9% vs. 18% casein (control) during pregnancy. Maternal low protein (MLP) offspring exhibit glucocorticoid-dependent raised systolic blood pressure throughout life (20-30 mm Hg above the control). To determine the molecular mechanisms underlying the role of alterations in glucocorticoid hormone action in the prenatal programming of hypertension in MLP offspring, tissues were analyzed for expression of the glucocorticoid receptor (GR), mineralocorticoid receptor (MR), 11betaHSD1, 11betaHSD2, and corticosteroid-responsive Na/K-adenosine triphosphatase alpha1 and beta1. GR protein (95 kDa) and messenger RNA (mRNA) expression in kidney, liver, lung, and brain was more than 2-fold greater in MLP vs. control offspring during fetal and neonatal life and was more than 3-fold higher during subsequent juvenile and adult life (P < 0.01). This was associated with increased levels of Na/K-adenosine triphosphatase alpha1- and beta1-subunit mRNA expression. Levels of MR gene expression remained unchanged. Exposure to the MLP diet also resulted in markedly reduced levels of 11betaHSD2 expression in the MLP placenta on days 14 and 20 of gestation (P < 0.001), underpinning similar effects on 11betaHSD2 enzyme activity that we reported previously. Levels were also markedly reduced in the kidney and adrenal of MLP offspring during fetal and postnatal life (P < 0.001). This programmed decline in 11betaHSD2 probably contributes to marked increases in glucocorticoid hormone action in these tissues and potentiates both GR- and MR-mediated induction of raised blood pressure. In contrast, levels of 11betaHSD1 mRNA expression in offspring central and peripheral tissues remained unchanged. In conclusion, we have demonstrated that mild protein restriction during pregnancy programs tissue-specific increases in glucocorticoid hormone action that are mediated by persistently elevated expression of GR and decreased expression of 11betaHSD2 during adult life. As glucocorticoids are potent regulators not only of fetal growth but also of blood pressure, our data suggest important potential molecular mechanisms contributing to the prenatal programming of hypertension by maternal undernutrition in the rat.

Monoamine oxidase in developing rat renal cortex: effect of dexamethasone treatment.

The expression of the biogenic amine degrading enzyme monoamine oxidases-A and -B depends on several factors including regional distribution, development and hormonal environment. In the present study, we investigated the expression of monoamine oxidases in developing kidney and their regulation by dexamethasone treatment. Immunoblots and enzyme assays, performed using [14C]5-hydroxytriptamine and [14C]beta-phenylethylamine as substrates for monoamine oxidases-A and -B, respectively, showed that monoamine oxidase-A is the isoenzyme largely predominant in 9-day-old rats renal cortex. Experiments performed in 5-week-old rats showed an increase in monoamine oxidase-B activity and a decrease in monoamine oxidase-A activity and substrate affinity. The changes of monoamine oxidase-A activity and affinity were mimicked by dexamethasone treatment (0.60 mg/kg body weight injected subcutaneously three times at intervals of 24 h) of 9-day-old rats. In contrast, dexamethasone administration induced a modification of monoamine oxidase-B activity opposite to that found between 9-day- and 5-week-old rats. Dexamethasone treatment did not modify immunoreactivity and mRNA corresponding to monoamine oxidases-A and -B indicating that changes of enzyme activities were unrelated to regulation of protein synthesis and mRNA turnover. These results show that monoamine oxidases-A and -B are differently expressed in developing renal cortex and are regulated by dexamethasone treatment.

Reactive oxygen species production by monoamine oxidases in intact cells.

Monoamine oxidase (MAO) A and B are mitochondrial enzymes involved in the oxidative deamination of endogenous and exogenous amines. At present, the production of H2O2 by MAO in intact cells and its functional consequences in cell function have not been extensively investigated. The aim of this study was to define whether, in intact cells, the metabolism of small amounts of MAO substrates was able to induce a detectable H2O2 production. Hydrogen peroxide production was measured using a luminol-amplified chemiluminescence assay in three cell types, rat mesangial cells, rabbit proximal tubule cells and Hep-G2 cells, containing different MAO A/MAO B ratios. Our results showed that cell incubation with tyramine (50 micromol/l) led to a time-dependent H2O2 generation which was fully inhibited by MAO A (clorgyline and RO 41-1049) and MAO B (selegiline and RO 19-6327) inhibitors. The extent of inhibition of H2O2 production by selective inhibitors was in agreement with the amount of MAO isoforms expressed in each cell type, as determined by Western blot analysis and enzyme assay. Altogether, these findings show that, in a normal cell environment, MAO can be a source of reactive oxygen species which could have a functional impact on cell functions. In addition, we propose the luminol-amplified chemiluminescence assay as a rapid and sensitive procedure to characterize the monoamine oxidase isoforms and their regulation in intact cells.

[Plasmodium prevalence and parasitic burden in blood donors of Brazzaville, Congo]. / Indices plasmodiques et charges parasitaires chez les donneurs de sang à Brazzaville, Congo.

To assess the frequency of malaria-infected blood donations in Brazzaville (Congo) thick films from all blood donors (n = 12,375, minimum per month: 857, maximum per month: 1,295; sex ratio: 9.6) at the Brazzaville University Hospital were examined quantitatively for Plasmodium (screening threshold: 20/microliters of blood) over one year (1989). The overall prevalence rate for all species of Plasmodium was 8.5%. It varied according with age but not with sex. P. falciparum predominated (92%), followed by P. malariae (7%) and P. ovale (3%). For P. falciparum: 1--the prevalence rate was 7.8% but varied over the year from 4.8% in August (6.2% for the dry season on the whole) to 11.5% in March (9.6% for the rainy season); 2--the parasitic load, also variable according to the season, was over 600/microliters in 24% of the cases (i.e. 1.9% of all donations) and over 6,000/microliters in 15 cases (i.e. 1.6% of the cases). In conclusion the proportion of blood donations infected with P. falciparum (with a parasitic load > or = 20/microliters) varied in Brazzaville from 6% in the dry season to 10% in the rainy season.

Apolipoprotein B polymorphism and altered apolipoprotein B concentrations in Congolese blacks.

The immunoreactivity of apolipoprotein B (apo B) in plasma obtained from 238 unrelated black African male subjects from the People's Republic of Congo was analysed by non-competitive Enzyme Linked-Immunosorbent Assay (ELISA) with monoclonal BIP 45 anti-LDL antibody. The polymorphism detected by BIP 45 monoclonal antibody is identical to the Ag(c,g) polymorphism. Antibody BIP 45 distinguishes three apo B allotypes (immunophenotypes) encoded by the two allelic genes apo B Ag(c) and apo B Ag(g). Because of co-dominant transmission, genotypes may be inferred from allotypes, and it has been shown that BIP 45 binds strongly to the Ag(c) factor and only weakly to the allelic Ag(g) factor. Analysis of the Congolese plasma samples indicated that 67.65% of them bound BIP 45 with low affinity (Ag(c-,g+) genotype), 28.15% with intermediate affinity (Ag(c+,g+) genotype) and 4.20% with high affinity (Ag(c+,g-) genotype). According to the Hardy-Weinberg equilibrium, this corresponds to gene frequencies of 0.817 and 0.183 for the type Ag(g)/Ag(c) alleles, respectively. After adjustment for age and body-mass index, it was found that the Ag(c) allele decreases the apo B level by 9.62 mg/dl and that the Ag(g) allele increases apo B by 0.43 mg/dl. Therefore, as much as 4.30% of the genetic variance for apo B level could be accounted for by the Ag(c,g) gene locus.

[Therapeutic trial with ivermectin in loiasis with medium and high microfilaremia]. / Essai thérapeutique de l'ivermectine au cours de la loase à moyenne et forte microfilarémie.

Treatment with ivermectin at the dosage of 200 microgram/kg in 28 Congolese loiasis patients led to an important decrease of the microfilaremia on day 7, with a reduction of about 90% of the initial parasite load. However, no negativation was observed and, moreover, the parasitemia did not change from day 7 to day 14. Tolerance was quite good, but weak to moderate reactions, linked to the lysis of the microfilariae, were observed in one third of the patients with a microfilaremia greater or equal to 2,500/mm3.

Clinical and biological study of Loa loa filariasis in Congolese.

Clinical and biological evaluations were carried out on 84 Congolese patients with parasitologically confirmed Loa loa filariasis (without concurrent infection with other filariae) and on 98 controls without filariasis. On the patients, 72 presented with microfilaremia; another 12 with negative blood tests were seen towards the end of an episode of subconjunctival migration of the adult worm. The incidence and severity of the clinical signs depended upon the method of recruitment. The 3 most common signs were pruritus and edema (both occurring in successive acute episodes affecting mainly the hands and forearms) and subconjunctival migration of adult filariae. Papulovesicular eruptions were located mainly on the arms. Headaches and arthralgia were noted more frequently than in the controls. No relation was found between the ABO blood groups and loiasis. Eosinophilia (higher in patients with symptoms) and raised serum IgE levels were found in nearly all patients and were strongly marked in approximately 66%. A positive correlation was observed between these 2 parameters. Fluorescent antibody levels (adult filaria Dipetalonema viteae antigen) were comparatively low in patients with microfilaremia.