Salivary cortisol differs with age and sex and shows inverse associations with WHR in Swedish women: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Most studies on cortisol have focused on smaller, selected samples. We therefore aimed to sex-specifically study the diurnal cortisol pattern and explore its association with abdominal obesity in a large unselected population.</p> <p>Methods</p> <p>In 2001–2004, 1811 men and women (30–75 years) were randomly selected from the Vara population, south-western Sweden (81% participation rate). Of these, 1671 subjects with full information on basal morning and evening salivary cortisol and anthropometric measurements were included in this cross-sectional study. Differences between groups were examined by general linear model and by logistic and linear regression analyses.</p> <p>Results</p> <p>Morning and Δ-cortisol (morning – evening cortisol) were significantly higher in women than men. In both genders older age was significantly associated with higher levels of all cortisol measures, however, most consistently with evening cortisol. In women only, age-adjusted means of WHR were significantly lower in the highest compared to the lowest quartile of morning cortisol (p = 0.036) and Δ-cortisol (p < 0.001), respectively. Furthermore, when comparing WHR above and below the mean, the age-adjusted OR in women for the lowest quartile of cortisol compared to the highest was 1.5 (1.0–2.2, p = 0.058) for morning cortisol and 1.9 (1.3–2.8) for Δ-cortisol. All findings for Δ-cortisol remained after adjustments for multiple covariates and were also seen in a linear regression analysis (p = 0.003).</p> <p>Conclusion</p> <p>In summary, our findings of generally higher cortisol levels in women than men of all ages are novel and the stronger results seen for Δ-cortisol as opposed to morning cortisol in the association with WHR emphasise the need of studying cortisol variation intra-individually. To our knowledge, the associations in this study have never before been investigated in such a large population sample of both men and women. Our results therefore offer important knowledge on the descriptive characteristics of cortisol in relation to age and gender, and on the impact that associations previously seen between cortisol and abdominal obesity in smaller, selected samples have on a population level.</p

Fat Oxidation, Fitness and Skeletal Muscle Expression of Oxidative/Lipid Metabolism Genes in South Asians: Implications for Insulin Resistance?

&lt;p&gt;&lt;b&gt;Background:&lt;/b&gt; South Asians are more insulin resistant than Europeans, which cannot be fully explained by differences in adiposity. We investigated whether differences in oxidative capacity and capacity for fatty acid utilisation in South Asians might contribute, using a range of whole-body and skeletal muscle measures.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Methodology/Principal Findings:&lt;/b&gt; Twenty men of South Asian ethnic origin and 20 age and BMI-matched men of white European descent underwent exercise and metabolic testing and provided a muscle biopsy to determine expression of oxidative and lipid metabolism genes and of insulin signalling proteins. In analyses adjusted for age, BMI, fat mass and physical activity, South Asians, compared to Europeans, exhibited; reduced insulin sensitivity by 26% (p = 0.010); lower VO2max (40.6±6.6 vs 52.4&#177;5.7 ml.kg−1.min−1, p = 0.001); and reduced fat oxidation during submaximal exercise at the same relative (3.77&#177;2.02 vs 6.55&#177;2.60 mg.kg−1.min−1 at 55% VO2max, p = 0.013), and absolute (3.46&#177;2.20 vs 6.00&#177;1.93 mg.kg−1.min−1 at 25 ml O2.kg−1.min−1, p = 0.021), exercise intensities. South Asians exhibited significantly higher skeletal muscle gene expression of CPT1A and FASN and significantly lower skeletal muscle protein expression of PI3K and PKB Ser473 phosphorylation. Fat oxidation during submaximal exercise and VO2max both correlated significantly with insulin sensitivity index and PKB Ser473 phosphorylation, with VO2max or fat oxidation during exercise explaining 10–13% of the variance in insulin sensitivity index, independent of age, body composition and physical activity.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusions/Significance:&lt;/b&gt; These data indicate that reduced oxidative capacity and capacity for fatty acid utilisation at the whole body level are key features of the insulin resistant phenotype observed in South Asians, but that this is not the consequence of reduced skeletal muscle expression of oxidative and lipid metabolism genes.&lt;/p&gt

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Higher education and more physical activity limit the development of obesity in a Swedish rural population The Skaraborg Project.

Objective:To investigate the prevalence and the secular trends of obesity in a rural Swedish community with emphasis on the association with socioeconomic status and lifestyle.Design:The Skaraborg Project cross-sectional population surveys were conducted in Vara, a rural community in the southwest of Sweden, every fifth year between 1977 and 2002.Subjects:A total of 3365 residents (1634 men and 1731 women) aged 30-60 years.Measurements:Obesity was defined as body mass index>/=30 kg m(-2). Information on ethnicity, marital status, socioeconomic status and lifestyle was collected by a questionnaire.Results:In 1977-1982, the average prevalence of obesity was 14% in both men and women, and in 2002, the prevalence of obesity was 19% in men and 21% in women. The age-adjusted odds ratio (OR) of obesity in 2002 was 1.48 (1.00, 2.20) in men and 1.41 (0.97, 2.05) in women. Without the simultaneous increase in the level of education and leisure-time physical activity (LTPA), the risk of developing obesity could have been considerably higher; in men OR=3.08 (1.88, 5.03) and in women OR=2.72 (1.66, 4.44). In multivariate models, higher levels of education and LTPA were associated with protective effects on obesity in both men (OR=0.60 (0.43, 0.83) and OR=0.50 (0.45, 0.79)) and women (OR=0.73 (0.54, 0.98) and OR=0.57 (0.42, 0.78)), respectively.Conclusions:This study revealed an upward secular trend in the prevalence of obesity in a rural community in Sweden. Increasing levels of education and LTPA limit this ongoing development of obesity. Public health strategies for the prevention of obesity should consider the special condition in rural environments.International Journal of Obesity advance online publication, 22 January 2008; doi:10.1038/sj.ijo.0803725