Scarcity of atrial fibrillation in a traditional African population: a community-based study

BACKGROUND: In western societies, atrial fibrillation is an increasingly common finding among the elderly. Established risk factors of atrial fibrillation include obesity, diabetes, hypertension, and cardiovascular disease. Atrial fibrillation has almost exclusively been studied in western populations where these risk factors are widely present. Therefore, we studied the epidemiology of atrial fibrillation in a traditional African community. METHODS: In rural Ghana, among 924 individuals aged 50 years and older, we recorded electrocardiograms to detect atrial fibrillation. As established risk factors, we documented waist circumference, body mass index (BMI), capillary glucose level, blood pressure, and electrocardiographic myocardial infarction. In addition, we determined circulating levels of interleukin-6 (IL6), a proinflammatory cytokine, and C-reactive protein (CRP), a marker of systemic inflammation. We compared the risk factors with reference data from the USA. RESULTS: Atrial fibrillation was detected in only three cases, equalling 0.3% (95% CI 0.1–1.0%). Waist circumference, BMI, and capillary glucose levels were very low. Hypertension and myocardial infarction were uncommon. Circulating levels of IL6 were similar, but those of CRP were lower compared with the USA. CONCLUSION: Atrial fibrillation is very scarce in this traditional African community. Its low prevalence compared with western societies can be explained by the rareness of its established risk factors, which are closely related to lifestyle, and by possible unmeasured differences in other risk factors or genetic factors

Hypertrophy of mature xenopus muscle fibres in culture induced by synergy of albumin and insulin

The aim of this study was to investigate effects of albumin and insulin separately as well as in combination on mature muscle fibres during long-term culture. Single muscle fibres were dissected from m. iliofibularis of Xenopus laevis and attached to a force transducer in a culture chamber. Fibres were cultured in a serum-free medium at slack length (mean sarcomere length 2.3 μm) for 8 to 22 days. The medium was supplemented with (final concentrations): (1) bovine insulin (6 nmol/L or 200-600 nmol/L), (2) 0.2% bovine albumin or (3) 0.2% bovine albumin in combination with insulin (120 nmol/L). In culture medium with insulin, 50% of the muscle fibres became in-excitable within 7-12 days, whereas the other 50% were stable. Caffeine contractures of in-excitable muscle fibres produced 80.4±2.4% of initial peak tetanic force, indicating impaired excitation-contraction (E-C) coupling in in-excitable fibres. In the presence of albumin, all cultured muscle fibres were stable for at least 10 days. Muscle fibres cultured in medium with insulin or albumin exclusively did not hypertrophy or change the number of sarcomeres in series. In contrast, muscle fibres cultured with both albumin and insulin showed an increase in tetanic force and fibre cross-sectional area of 19.6±2.8% and 32.5±4.9%, respectively, (means±SEM.; P=0.007) after 16.3±1.7 days, whereas the number of sarcomeres in series remained unchanged. We conclude that albumin prevents muscle fibre damage and preserves E-C coupling in culture. Furthermore, albumin is important in regulating muscle fibre adaptation by a synergistic action with growth factors like insulin. © 2008 The Author(s)

ICAR: endoscopic skull‐base surgery

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