Correction to: Partitioning of adipose lipid metabolism by altered expression and function of PPAR isoforms after bariatric surgery.

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Partitioning of adipose lipid metabolism by altered expression and function of PPAR isoforms after bariatric surgery.

BACKGROUND: Bariatric surgery remains the most effective treatment for reducing adiposity and eliminating type 2 diabetes; however, the mechanism(s) responsible have remained elusive. Peroxisome proliferator-activated receptors (PPAR) encompass a family of nuclear hormone receptors that upon activation exert control of lipid metabolism, glucose regulation and inflammation. Their role in adipose tissue following bariatric surgery remains undefined. MATERIALS AND METHODS: Subcutaneous adipose tissue biopsies and serum were obtained and evaluated from time of surgery and on postoperative day 7 in patients randomized to Roux-en-Y gastric bypass (n=13) or matched caloric restriction (n=14), as well as patients undergoing vertical sleeve gastrectomy (n=33). Fat samples were evaluated for changes in gene expression, protein levels, ß-oxidation, lipolysis and cysteine oxidation. RESULTS: Within 7 days, bariatric surgery acutely drives a change in the activity and expression of PPARγ and PPARδ in subcutaneous adipose tissue thereby attenuating lipid storage, increasing lipolysis and potentiating lipid oxidation. This unique metabolic alteration leads to changes in downstream PPARγ/δ targets including decreased expression of fatty acid binding protein (FABP) 4 and stearoyl-CoA desaturase-1 (SCD1) with increased expression of carnitine palmitoyl transferase 1 (CPT1) and uncoupling protein 2 (UCP2). Increased expression of UCP2 not only facilitated fatty acid oxidation (increased 15-fold following surgery) but also regulated the subcutaneous adipose tissue redoxome by attenuating protein cysteine oxidation and reducing oxidative stress. The expression of UCP1, a mitochondrial protein responsible for the regulation of fatty acid oxidation and thermogenesis in beige and brown fat, was unaltered following surgery. CONCLUSIONS: These results suggest that bariatric surgery initiates a novel metabolic shift in subcutaneous adipose tissue to oxidize fatty acids independently from the beiging process through regulation of PPAR isoforms. Further studies are required to understand the contribution of this shift in expression of PPAR isoforms to weight loss following bariatric surgery.

Obesity and bariatric surgery: a systematic review of associations with defecatory dysfunction.

BACKGROUND: Obesity rates are rapidly growing in the developed world. While upper gastrointestinal disturbances and urinary incontinence are independently associated with obesity, the relationship between obesity and defecatory dysfunction is less well defined. OBJECTIVES: To summarize the literature on faecal incontinence, diarrhoea and constipation in obese patients and its effects of bariatric surgery. SEARCH STRATEGY: A Medline search was carried out on articles published from January 1966 to March 2010. SELECTION CRITERIA: Original articles on adult obese or morbidly obese patients were identified, including results following bariatric surgery that reported faecal incontinence, diarrhoea or constipation. Other forms of pelvic floor dysfunction were excluded. Main outcome measures included faecal incontinence, diarrhoea and constipation rates and their severity in obese patients and following bariatric surgery. RESULTS: Twenty studies reported defecatory outcomes in obese patients (n = 14) and after bariatric surgery (n = 6). While constipation rates were similar, the rates of faecal incontinence and diarrhoea were higher in obese patients compared with non-obese patients. The exact rates of these conditions, and the correlations between body mass index (BMI) and faecal incontinence, diarrhoea and constipation, were not clear. Faecal incontinence improved after Roux-en-Y gastric bypass in studies with preoperative data. The effects of bariatric surgery on diarrhoea were unclear. CONCLUSION: Few studies have assessed the correlations between obesity and defecatory function and the effect of bariatric surgery. Studies were often not well controlled and used non-uniform instruments to assess bowel function. Obesity appears to be correlated with higher rates of faecal incontinence and diarrhoea. The effects of bariatric surgery on these conditions are not well defined. Well-controlled studies correlating outcome with physiological pelvic floor function are needed.