Impact of Gender on the Myocardial Metabolic Response to Obesity

ObjectivesWe sought to determine the gender-specific effects of obesity on myocardial metabolism, work, and efficiency.BackgroundMyocardial metabolism abnormalities may contribute to the development of obesity-related heart failure. Increased myocardial oxygen consumption (MVO2) and fatty acid (FA) metabolism and decreased efficiency occur with obesity in women. It is unknown whether similar changes occur with obesity in men.MethodsWe quantified cardiac work, efficiency, myocardial blood flow (MBF), MVO2, glucose, and FA metabolism with echocardiography and positron emission tomography in nonobese and obese men and women (N = 86).ResultsThere were significant differences between the obese (n = 35) and nonobese (n = 51) subjects in age, body composition, plasma lipids, and insulin resistance in addition to differences between the men (n = 30) and women (n = 56) in body composition and plasma lipids. Female gender independently predicted increased cardiac work (p < 0.001). Female gender also related to lower efficiency (p < 0.05). Obesity and female gender independently predicted greater MBF (p < 0.01, p < 0.0005, respectively) and MVO2 (p < 0.0005, p < 0.0001). Myocardial glucose uptake was not different among the 4 subject groups, but obesity and gender interacted in predicting glucose uptake (p < 0.05). Lower myocardial glucose utilization was independently predicted by female gender (p < 0.05), and it independently predicted lower myocardial glucose utilization/plasma insulin (p < 0.05). Obesity and gender significantly interacted in the determination of glucose utilization/plasma insulin (p = 0.01). There were no differences in FA uptake among the 4 groups, and although increasing obesity correlated with greater myocardial FA utilization and oxidation; female gender (p < 0.005, p < 0.01) and plasma triglycerides (p < 0.05, p < 0.005) were their independent predictors.ConclusionsWomen's and men's myocardial metabolic responses to obesity are not exactly the same. Obesity and gender modulate MBF and MVO2, are related to myocardial substrate metabolism, and sometimes interact in its prediction. Gender modifies efficiency. Gender-related differences in myocardial metabolism may affect the development of/adaptation to obesity-related cardiac disease

Gut microbiota functions: metabolism of nutrients and other food components

The diverse microbial community that inhabits the human gut has an extensive metabolic repertoire that is distinct from, but complements the activity of mammalian enzymes in the liver and gut mucosa and includes functions essential for host digestion. As such, the gut microbiota is a key factor in shaping the biochemical profile of the diet and, therefore, its impact on host health and disease. The important role that the gut microbiota appears to play in human metabolism and health has stimulated research into the identification of specific microorganisms involved in different processes, and the elucidation of metabolic pathways, particularly those associated with metabolism of dietary components and some host-generated substances. In the first part of the review, we discuss the main gut microorganisms, particularly bacteria, and microbial pathways associated with the metabolism of dietary carbohydrates (to short chain fatty acids and gases), proteins, plant polyphenols, bile acids, and vitamins. The second part of the review focuses on the methodologies, existing and novel, that can be employed to explore gut microbial pathways of metabolism. These include mathematical models, omics techniques, isolated microbes, and enzyme assays

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Ten golden rules for optimal antibiotic use in hospital settings: the WARNING call to action

Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or “golden rules,” for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice

Pathways for the biosynthesis of polyunsaturated fatty acids

A review

Liver, muscle, and adipose tissue insulin action is directly related to intrahepatic triglyceride content in obese subjects

BACKGROUND & AIMS: Nonalcoholic fatty liver disease is associated with insulin resistance and diabetes. The purpose of this study was to determine the relationship between intrahepatic triglyceride (IHTG) content and insulin action in liver (suppression of glucose dioduction), skeletal muscle (stimulation of glucose uptake) and adipose tissue (suppression of lipolysis) in non-diabetic, obese subjects. METHODS: A euglycemic-hyperinsulinemic clamp procedure and stable isotopically labeled tracer infusions were used to assess insulin action, and magnetic resonance spectroscopy was used to determine IHTG content, in 42 non-diabetic, obese subjects (BMI 36±4 kg/m(2)) who had a wide range of IHTG content (1%−46%). RESULTS: Hepatic insulin sensitivity, assessed as a function of glucose production rate and plasma insulin concentration, was inversely correlated with IHTG content (r=−0.599; P<0.001). The ability of insulin to suppress the release of fatty acids from adipose tissue and to stimulate glucose uptake by skeletal muscle were also inversely correlated with IHTG content (adipose tissue: r=−0.590; P<0.001; skeletal muscle: r=−0.656; P<0.001). Multivariate linear regression analyses found that IHTG content was the best predictor of insulin action in liver, skeletal muscle and adipose tissue, independent of BMI and percent body fat, and accounted for 34%, 42%, and 44% of the variability in these tissues, respectively (P< 0.001 for each model). CONCLUSIONS: These results demonstrate that progressive increases in IHTG content are associated with progressive impairment of insulin action in liver, skeletal muscle and adipose tissue in non-diabetic, obese subjects. Therefore, NAFLD should be considered part of a multi-organ system derangement in insulin sensitivity