Teresa Bartholomeu

Exercise improves endothelial function: A local analysis of production of nitric oxide and reactive oxygen species

This study aimed at investigating the acute effects of aerobic exercise on endothelium-dependent vasomotor function of rat aorta, as well as mechanisms involved in endothelial nitric oxide (NO) bioactivity. Wistar rats were assigned to either a resting control (C, n = 21) or acutely exercised (E, n = 21) groups (60 min, 55-60% of maximum speed). After exercise, thoracic aorta was excised and cut into rings. Two rings were promptly applied to evaluate vasomotor function and the rest of aorta was used for additional measurements. Acute exercise significantly improved maximum ACh-induced relaxation (C, 91.6 ± 1.2 vs. E, 102.4 ± 1.7%, p < 0.001) and sensitivity to ACh (C, -7.3 ± 0.06 vs. E, -7.3 ± 0.02 log M, p < 0.01), and was accompanied by significantly increases on serine1177 eNOS phosphorylation, reflecting its enhanced activation. However, acute exercise also enhanced both superoxide and hydrogen peroxide production, as assayed by dihydroethidium oxidation, lucigenin chemiluminescence and Amplex Red assays. We also provided evidence for Nox2 NADPH oxidase (Nox) activation through gp91dstat-mediated inhibition of superoxide signals. Enhanced arterial relaxations associated with acute exercise were nearly-completely prevented by catalase, suggesting a role for paracrine hydrogen peroxide. Despite increased detectable oxidant generation, cellular oxidative stress was not evident, as suggested by unaltered GSH:GSSG ratio and lipid hydroperoxides. Collectively, these results demonstrate that one bout of moderate aerobic exercise improves endothelial function by increasing NO bioavailability, while superoxide and hydrogen peroxide are generated in a controlled fashion.

Risco cardiovascular e prática de atividade física em crianças e adolescentes de Muzambinho/MG: influência do gênero e da idade

INTRODUCTION AND OBJECTIVE: Cardiovascular disease begins at infancy and it has been linked to the presence of cardiovascular risk factors (CRF). Prevalence of these factors varies a lot among different Brazilian populations and has been mostly studied in big and medium size cities. Thus, this study assessed the prevalence of CRF and physical activity (PA) in children and adolescents from Muzambinho, a small city in the state of Minas Gerais. METHODS: 205 subjects (7 to 18 years - 108 males) were studied. Body weight and height, glycemia, cholesterolemia, blood pressure (BP), and PA were measured. Comparisons were made by Qui-square test. RESULTS: Obesity and altered values of BP, glycemia, and cholesterolemia were found, respectively, in 19, 11, 5 and 15% of the subjects. There was no difference between genders, while the prevalence of smokers, drinkers, altered BP, and inactivity increased with age. Seventy-nine percent of the subjects practiced community PA; 10% occupational PA; 97% physical education classes; 72% PA during school recess; and 90% leisure time PA. Ninety-two percent of them were active. Occupational PA was higher in girls, and increased with age in boys. Leisure time and during school recess PA decreased with age in both genders. CONCLUSION: Except for physical inactivity, prevalence of CRF was high, did not differ between genders, and increased with age. High levels of all kinds of PA were found; they differed between genders, and decreased with age.

Genetic and environmental influences on blood pressure and physical activity: a study of nuclear families from Muzambinho, Brazil

Blood pressure (BP) and physical activity (PA) levels are inversely associated. Since genetic factors account for the observed variation in each of these traits, it is possible that part of their association may be related to common genetic and/or environmental influences. Thus, this study was designed to estimate the genetic and environmental correlations of BP and PA phenotypes in nuclear families from Muzambinho, Brazil. Families including 236 offspring (6 to 24 years) and their 82 fathers and 122 mothers (24 to 65 years) were evaluated. BP was measured, and total PA (TPA) was assessed by an interview (commuting, occupational, leisure time, and school time PA). Quantitative genetic modeling was used to estimate maximal heritability (h2), and genetic and environmental correlations. Heritability was significant for all phenotypes (systolic BP: h2 = 0.37 ± 0.10, P < 0.05; diastolic BP: h2 = 0.39 ± 0.09, P < 0.05; TPA: h2 = 0.24 ± 0.09, P < 0.05). Significant genetic (rg) and environmental (re) correlations were detected between systolic and diastolic BP (rg = 0.67 ± 0.12 and re = 0.48 ± 0.08, P < 0.05). Genetic correlations between BP and TPA were not significant, while a tendency to an environmental cross-trait correlation was found between diastolic BP and TPA (re = -0.18 ± 0.09, P = 0.057). In conclusion, BP and PA are under genetic influences. Systolic and diastolic BP share common genes and environmental influences. Diastolic BP and TPA are probably under similar environmental influences.

Desafios no estudo de famílias nucleares: etapas iniciais de análise

Os estudos em familias nucleares possibilitam a avaliacao da existencia de agregacao familiar numa dada caracteristica, permitindo avaliar o quanto da variacao dessa caracteristica na populacao pode ser atribuida a variacao genetica existente entre os sujeitos. Os resultados desses estudos possibilitam a elaboracao de estrategias de intervencao mais eficientes e direcionadas, alem de serem o ponto de partida para estudos mais complexos de epidemiologia genetica, como a identificacao de genes responsaveis pela caracteristica em analise. Nas areas de Ciencias do Desporto e Educacao Fisica, alguns estudos tem sido realizados para verificar a existencia de agregacao familiar e a influencia genetica em tracos relacionados a estados de saude, atividade e desempenho fisicos. Entretanto, esses esforcos revelam-se escassos em populacoes lusofonas e sao, praticamente inexistentes, na populacao brasileira. Dessa forma, o presente artigo teve como proposito abordar, de forma simples e introdutoria, aspectos importantes de estudos em familias nucleares. Para tanto, foram analisadas as duas fases iniciais dos estudos de Epidemiologia Genetica, ou seja, a identificacao e quantificacao da agregacao familiar e da heritabilidade. As diferentes etapas de analise foram exemplificadas com dados reais, coletados em familias nucleares pertencentes a um estudo realizado na cidade de Muzambinho-MG. Espera-se que esse artigo forneca subsidios e estimulo aos pesquisadores iniciantes neste tipo de investigacao.