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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, β-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.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

BackgroundIt is critical to ensure appropriate and consistent sleeve size and orientation during laparoscopic sleeve gastrectomy (LSG). Various devices are used to achieve this, including weighted rubber bougies, esophagogastroduodenoscopy (EGD), and suction calibration systems (SCS). Prior reports suggest that SCSs may decrease operative time and stapler load firings but are limited by single-surgeon experience and retrospective design. We performed the first randomized controlled trial comparing SCS against EGD in patients undergoing LSG to investigate whether the SCS decreases the number of stapler load firings.MethodsThis was a randomized, non-blinded study from a single MBSAQIP-accredited academic center. Appropriate LSG candidates ≥ 18 years of age were randomized to EGD or SCS calibration. Exclusion criteria included prior gastric or bariatric surgery, detection of hiatal hernia before surgery, and intraoperative hiatal hernia repair. A randomized block design was employed controlling for body mass index, gender, and race. Seven surgeons employed a standardized LSG operative technique. The primary endpoint was the number of stapler load firings. Secondary endpoints were operative duration, reflux symptoms, and change in total body weight (TBW). Endpoints were analyzed via t-test.ResultsA total of 125 LSG patients (84% female) underwent study enrollment, with an average age of 44 ± 12 years and average BMI of 49 ± 8 kg/m2. Overall, 117 patients were randomized to receive EGD (n = 59) or SCS (n = 58) calibration. No significant differences in baseline characteristics were identified. The mean number of stapler load firings for EGD and SCS groups were 5.43 ± 0.89 and 5.31 ± 0.81, respectively (p = 0.463). The mean operative times for EGD and SCS groups were 94.4 ± 36.5 and 93.1 ± 27.9 min, respectively (p = 0.83). There were no significant differences in post-operative reflux, TBW loss, or complications.ConclusionUse of EGD and SCS resulted in a similar number of LSG stapler load firings and operative duration. Additional research is needed to compare LSG calibration devices in different patients and settings to optimize surgical technique.