Exercise-Induced Increases in Insulin Sensitivity After Bariatric Surgery Are Mediated By Muscle Extracellular Matrix Remodeling.

Exercise seems to enhance the beneficial effect of bariatric (Roux-en-Y gastric bypass [RYGB]) surgery on insulin resistance. We hypothesized that skeletal muscle extracellular matrix (ECM) remodeling may underlie these benefits. Women were randomized to either a combined aerobic and resistance exercise training program following RYGB (RYGB + ET) or standard of care (RYGB). Insulin sensitivity was assessed by oral glucose tolerance test. Muscle biopsy specimens were obtained at baseline and 3 and 9 months after surgery and subjected to comprehensive phenotyping, transcriptome profiling, molecular pathway identification, and validation in vitro. Exercise training improved insulin sensitivity beyond surgery alone (e.g., Matsuda index: RYGB 123% vs. RYGB + ET 325%; P ≤ 0.0001). ECM remodeling was reduced by surgery alone, with an additive benefit of surgery and exercise training (e.g., collagen I: RYGB -41% vs. RYGB + ET -76%; P ≤ 0.0001). Exercise and RYGB had an additive effect on enhancing insulin sensitivity, but surgery alone did not resolve insulin resistance and ECM remodeling. We identified candidates modulated by exercise training that may become therapeutic targets for treating insulin resistance, in particular, the transforming growth factor-ß1/SMAD 2/3 pathway and its antagonist follistatin. Exercise-induced increases in insulin sensitivity after bariatric surgery are at least partially mediated by muscle ECM remodeling.

Physicochemical differences between malanga (Xanthosoma sagittifolium) and potato (Solanum tuberosum) tubers are associated with differential effects on the gut microbiome.

Malanga (Xanthosoma sagittifolium) is used as a medicinal food for infant development and gastritis. We compared the physicochemical properties and gut microbial effects of malanga versus potato (Solanum tuberosum) using nutritional analysis, rheometry, in vitro TNO Intestinal Model, and C57Bl/6J mouse models. Malanga was characterized by higher starch (70.7% v. 66.3%), lower amylose:amylopectin (0.33 v. 0.59), higher free sugar (5.44% v. 3.23%), lower viscosity (271.0 v. 863.0 mPa.s), and higher bioaccessible and bioavailable sugar (0.89 v. 0.11 g bioaccessible sucrose per 20 g load in vitro; blood glucose levels of 129.1 v. 95.2 and 133.8 v. 104.3 mg/dL after 20 and 60 min in vivo). Gut microbiota of mice fed a high fat diet containing 20% malanga for 14 d exhibited significantly higher α diversity than those fed 20% potato, indicating that minor physicochemical differences between similar tuber crops are associated with significantly different effects on the gut microbiome.

High-amylose resistant starch increases hormones and improves structure and function of the gastrointestinal tract: a microarray study.

BACKGROUND/AIMS: Type 2 resistant starch from high-amylose maize (HAM-RS2) is associated with increased fermentation, increased expression of proglucagon (gene for GLP-1) and peptide YY (PYY) genes in the large intestine, and improved health. To determine what other genes are up- or downregulated with feeding of HAM-RS2, a microarray was performed. METHODS: Adult, male Sprague Dawley rats were fed one of the following three diets for a 4-week study period: cornstarch control (CC, 3.74 kcal/g), dietary energy density control (EC, 3.27 kcal/g), and 30% HAM-RS2 (RS, 3.27 kcal/g). Rat microarray with ∼27,000 genes and validation of 94 representative genes with multiple qPCR were used to determine gene expression in total RNA extracts of cecal cells from rats. The RS versus EC comparison tested effects of fermentation as energy density of the diet was controlled. RESULTS: For the RS versus EC comparison, 86% of the genes were validated from the microarray and the expression indicates promotion of cell growth, proliferation, differentiation, and apoptosis. Gut hormones GLP-1 and PYY were increased. CONCLUSIONS: Gene expression results predict improved structure and function of the GI tract. Production of gut hormones may promote healthy functions beyond the GI tract.