Lipoprotein Lipase Overexpression in Skeletal Muscle Attenuates Weight Regain by Potentiating Energy Expenditure

Moderate weight loss improves numerous risk factors for cardiometabolic disease; however, long-term weight loss maintenance (WLM) is often thwarted by metabolic adaptations that suppress energy expenditure and facilitate weight regain. Skeletal muscle has a prominent role in energy homeostasis; therefore, we investigated the effect of WLM and weight regain on skeletal muscle in rodents. In skeletal muscle of obesity-prone rats, WLM reduced fat oxidative capacity and downregulated genes involved in fat metabolism. Interestingly, even after weight was regained, genes involved in fat metabolism were also reduced. We then subjected mice with skeletal muscle lipoprotein lipase overexpression (mCK-hLPL), which augments fat metabolism, to WLM and weight regain and found that mCK-hLPL attenuates weight regain by potentiating energy expenditure. Irrespective of genotype, weight regain suppressed dietary fat oxidation and downregulated genes involved in fat metabolism in skeletal muscle. However, mCK-hLPL mice oxidized more fat throughout weight regain and had greater expression of genes involved in fat metabolism and lower expression of genes involved in carbohydrate metabolism during WLM and regain. In summary, these results suggest that skeletal muscle fat oxidation is reduced during WLM and regain, and therapies that improve skeletal muscle fat metabolism may attenuate rapid weight regain.     

Diagnostic performance of nocturnal penile tumescence studies in healthy, dysfunctional (impotent), and depressed men

Nocturnal penile tumescence (NPT) studies were evaluated in 17 men with a clinical diagnosis of organic erectile dysfunction in comparison to age-matched healthy controls (n = 17) and depressed men (n = 17). The dysfunctional group had significantly fewer NPT episodes and reduced maximal penile tip changes when compared to healthy controls and depressed patients. Further, the dysfunctional group had significantly diminished erectile fullness and reduced penile rigidity. Diagnostic performance of polygraphic (night 1) and visual inspection (nights 2 or 3) components of the NPT protocol were examined in these criterion groups. A diagnostic classification based on polygraphic measures successfully discriminated 73.5% of dysfunctional and healthy control subjects, but classified 47% of depressives in the dysfunctional range. Use of visual inspection indices correctly identified 88% of the dysfunctional sample and 94% of normal controls, and reduced the "false-positive" rate in depression to only 18%. Results support the diagnostic utility of NPT studies, particularly when enhanced by visual inspection procedures. Nevertheless, the presence of major depression may confound interpretation of such studies.