Novel multiparametric bulk and single EV pipeline for adipose cell-specific biomarker discovery in paired human biospecimens

Obesity is a global health crisis that contributes to morbidity and mortality worldwide. Obesity's comorbid association with a variety of diseases, from metabolic syndrome to neurodegenerative disease, underscores the critical need to better understand the pathobiology of obesity. Adipose tissue, once seen as an inert storage depot, is now recognized as an active endocrine organ, regulating metabolic and systemic homeostasis. Recent studies spotlight the theranostic utility of extracellular vesicles (EVs) as novel biomarkers and drivers of disease, including obesity-related complications. Adipose-derived EVs (ADEVs) have garnered increased interest for their roles in diverse diseases, however robust isolation and characterization protocols for human, cell-specific EV subsets are limited. Herein, we directly address this technical challenge by establishing a multiparametric analysis framework that leverages bulk and single EV characterization, mRNA phenotyping and proteomics of human ADEVs directly from paired visceral adipose tissue, cultured mature adipocyte conditioned media, and plasma from obese subjects undergoing bariatric surgery. Importantly, rigorous EV phenotyping at the tissue and cell-specific level identified top 'adipose liquid biopsy' candidates that were validated in circulating plasma EVs from the same patient. In summary, our study paves the way toward a tissue and cell-specific, multiparametric framework for studying tissue and circulating adipose EVs in obesity-driven disease.

How Does the Sequence of the American Board of Surgery Examinations Impact Pass/Fail Outcomes?

OBJECTIVE

Historically, the American Board of Surgery required surgeons to pass the qualifying examination (QE) before taking the certifying examination (CE). However, in the 2020-2021 academic year, with mitigating circumstances related to COVID-19, the ABS removed this sequencing requirement to facilitate the certification process for those candidates who were negatively impacted by a QE delivery failure. This decoupling of the traditional order of exam delivery has provided a natural comparator to the traditional route and an analysis of the impact of examination sequencing on candidate performance.

METHODS

All candidates who applied for the canceled July 2020 QE were allowed to take the CE before passing the QE. The sample was then reduced to include only first-time candidates to ensure comparable groups for performance outcomes. Logistic regression was used to analyze the relationship between the order of taking the QE and the CE, controlling for other examination performance, international medical graduate status, and gender.

RESULTS

Only first-time candidates who took both examinations were compared (n=947). Examination sequence was not a significant predictor of QE pass/fail outcomes, OR=0.54; 95% CI, 0.19-1.61, P =0.26. However, examination sequence was a significant predictor of CE pass/fail outcomes, OR=2.54; 95% CI, 1.46-4.68, P =0.002.

CONCLUSIONS

This important study suggests that preparation for the QE increases the probability of passing the CE and provides evidence that knowledge may be foundational for clinical judgment. The ABS will consider these findings for examination sequencing moving forward.

Truth of Colorectal Enhanced Recovery Programs: Process Measure Compliance in 151 Hospitals

BACKGROUND

Commonly cited studies have reported substantial improvements (defined as >20%) in process measure compliance after implementation of colorectal enhanced recovery programs (ERPs). However, hospitals have anecdotally reported difficulties in achieving similar improvement gains. This study evaluates improvement uniformity among 151 hospitals exposed to an 18-month implementation protocol for 6 colorectal ERP process measures (oral antibiotics, mechanical bowel preparation, multimodal pain control, early mobilization, early liquid intake, and early solid intake).

STUDY DESIGN

One hundred fifty-one hospitals implemented a colorectal ERP with pathway, educational and supporting materials, and data capture protocols; 906 opportunities existed for process compliance improvement across the cohort (151 hospitals × 6 process measures). However, 240 opportunities were excluded due to high starting compliance rates (ie compliance >80%) and 3 opportunities were excluded because compliance rates were recorded for fewer than 2 cases. Thus, 663 opportunities for improvement across 151 hospitals were studied.

RESULTS

Of 663 opportunities, minimal improvement (0% to 20% increase in compliance) occurred in 52% of opportunities, substantial improvement (>20% increase in compliance) in 20%, and worsening compliance occurred in 28%. Of the 6 processes, multimodal pain control and use of oral antibiotics improved the most.

CONCLUSIONS

Contrary to published ERP literature, the majority of study hospitals had difficulty improving process compliance with 80% of the opportunities not achieving substantial improvement. This discordance between ERP implementation success rates reported in the literature and what is observed in a large sample could reflect differences in hospitals' culture or characteristics, or a publication bias. Attention needs to be directed toward improving ERP adoption across the spectrum of hospital types.

Association of Bariatric Surgery With Cancer Risk and Mortality in Adults With Obesity

IMPORTANCE

Obesity increases the incidence and mortality from some types of cancer, but it remains uncertain whether intentional weight loss can decrease this risk.

OBJECTIVE

To investigate whether bariatric surgery is associated with lower cancer risk and mortality in patients with obesity.

DESIGN, SETTING, AND PARTICIPANTS

In the SPLENDID (Surgical Procedures and Long-term Effectiveness in Neoplastic Disease Incidence and Death) matched cohort study, adult patients with a body mass index of 35 or greater who underwent bariatric surgery at a US health system between 2004 and 2017 were included. Patients who underwent bariatric surgery were matched 1:5 to patients who did not undergo surgery for their obesity, resulting in a total of 30 318 patients. Follow-up ended in February 2021.

EXPOSURES

Bariatric surgery (n = 5053), including Roux-en-Y gastric bypass and sleeve gastrectomy, vs nonsurgical care (n = 25 265).

MAIN OUTCOMES AND MEASURES

Multivariable Cox regression analysis estimated time to incident obesity-associated cancer (a composite of 13 cancer types as the primary end point) and cancer-related mortality.

RESULTS

The study included 30 318 patients (median age, 46 years; median body mass index, 45; 77% female; and 73% White) with a median follow-up of 6.1 years (IQR, 3.8-8.9 years). The mean between-group difference in body weight at 10 years was 24.8 kg (95% CI, 24.6-25.1 kg) or a 19.2% (95% CI, 19.1%-19.4%) greater weight loss in the bariatric surgery group. During follow-up, 96 patients in the bariatric surgery group and 780 patients in the nonsurgical control group had an incident obesity-associated cancer (incidence rate of 3.0 events vs 4.6 events, respectively, per 1000 person-years). The cumulative incidence of the primary end point at 10 years was 2.9% (95% CI, 2.2%-3.6%) in the bariatric surgery group and 4.9% (95% CI, 4.5%-5.3%) in the nonsurgical control group (absolute risk difference, 2.0% [95% CI, 1.2%-2.7%]; adjusted hazard ratio, 0.68 [95% CI, 0.53-0.87], P = .002). Cancer-related mortality occurred in 21 patients in the bariatric surgery group and 205 patients in the nonsurgical control group (incidence rate of 0.6 events vs 1.2 events, respectively, per 1000 person-years). The cumulative incidence of cancer-related mortality at 10 years was 0.8% (95% CI, 0.4%-1.2%) in the bariatric surgery group and 1.4% (95% CI, 1.1%-1.6%) in the nonsurgical control group (absolute risk difference, 0.6% [95% CI, 0.1%-1.0%]; adjusted hazard ratio, 0.52 [95% CI, 0.31-0.88], P = .01).

CONCLUSIONS AND RELEVANCE

Among adults with obesity, bariatric surgery compared with no surgery was associated with a significantly lower incidence of obesity-associated cancer and cancer-related mortality.

Association of Bariatric Surgery With Major Adverse Liver and Cardiovascular Outcomes in Patients With Biopsy-Proven Nonalcoholic Steatohepatitis

IMPORTANCE

No therapy has been shown to reduce the risk of serious adverse outcomes in patients with nonalcoholic steatohepatitis (NASH).

OBJECTIVE

To investigate the long-term relationship between bariatric surgery and incident major adverse liver outcomes and major adverse cardiovascular events (MACE) in patients with obesity and biopsy-proven fibrotic NASH without cirrhosis.

DESIGN, SETTING, AND PARTICIPANTS

In the SPLENDOR (Surgical Procedures and Long-term Effectiveness in NASH Disease and Obesity Risk) study, of 25 828 liver biopsies performed at a US health system between 2004 and 2016, 1158 adult patients with obesity were identified who fulfilled enrollment criteria, including confirmed histological diagnosis of NASH and presence of liver fibrosis (histological stages 1-3). Baseline clinical characteristics, histological disease activity, and fibrosis stage of patients who underwent simultaneous liver biopsy at the time of bariatric surgery were balanced with a nonsurgical control group using overlap weighting methods. Follow-up ended in March 2021.

EXPOSURES

Bariatric surgery (Roux-en-Y gastric bypass, sleeve gastrectomy) vs nonsurgical care.

MAIN OUTCOMES AND MEASURES

The primary outcomes were the incidence of major adverse liver outcomes (progression to clinical or histological cirrhosis, development of hepatocellular carcinoma, liver transplantation, or liver-related mortality) and MACE (a composite of coronary artery events, cerebrovascular events, heart failure, or cardiovascular death), estimated using the Firth penalized method in a multivariable-adjusted Cox regression analysis framework.

RESULTS

A total of 1158 patients (740 [63.9%] women; median age, 49.8 years [IQR, 40.9-57.9 years], median body mass index, 44.1 [IQR, 39.4-51.4]), including 650 patients who underwent bariatric surgery and 508 patients in the nonsurgical control group, with a median follow-up of 7 years (IQR, 4-10 years) were analyzed. Distribution of baseline covariates, including histological severity of liver injury, was well-balanced after overlap weighting. At the end of the study period in the unweighted data set, 5 patients in the bariatric surgery group and 40 patients in the nonsurgical control group experienced major adverse liver outcomes, and 39 patients in the bariatric surgery group and 60 patients in the nonsurgical group experienced MACE. Among the patients analyzed with overlap weighting methods, the cumulative incidence of major adverse liver outcomes at 10 years was 2.3% (95% CI, 0%-4.6%) in the bariatric surgery group and 9.6% (95% CI, 6.1%-12.9%) in the nonsurgical group (adjusted absolute risk difference, 12.4% [95% CI, 5.7%-19.7%]; adjusted hazard ratio, 0.12 [95% CI, 0.02-0.63]; P = .01). The cumulative incidence of MACE at 10 years was 8.5% (95% CI, 5.5%-11.4%) in the bariatric surgery group and 15.7% (95% CI, 11.3%-19.8%) in the nonsurgical group (adjusted absolute risk difference, 13.9% [95% CI, 5.9%-21.9%]; adjusted hazard ratio, 0.30 [95% CI, 0.12-0.72]; P = .007). Within the first year after bariatric surgery, 4 patients (0.6%) died from surgical complications, including gastrointestinal leak (n = 2) and respiratory failure (n = 2).

CONCLUSIONS AND RELEVANCE

Among patients with NASH and obesity, bariatric surgery, compared with nonsurgical management, was associated with a significantly lower risk of incident major adverse liver outcomes and MACE.

Cardiovascular Outcomes in Patients With Type 2 Diabetes and Obesity: Comparison of Gastric Bypass, Sleeve Gastrectomy, and Usual Care

OBJECTIVE

To determine which one of the two most common metabolic surgical procedures is associated with greater reduction in risk of major adverse cardiovascular events (MACE) in patients with type 2 diabetes mellitus (T2DM) and obesity.

RESEARCH DESIGN AND METHODS

A total of 13,490 patients including 1,362 Roux-en-Y gastric bypass (RYGB), 693 sleeve gastrectomy (SG), and 11,435 matched nonsurgical patients with T2DM and obesity who received their care at the Cleveland Clinic (1998-2017) were analyzed, with follow-up through December 2018. With multivariable Cox regression analysis we estimated time to incident extended MACE, defined as first occurrence of coronary artery events, cerebrovascular events, heart failure, nephropathy, atrial fibrillation, and all-cause mortality.

RESULTS

The cumulative incidence of the primary end point at 5 years was 13.7% (95% CI 11.4-15.9) in the RYGB groups and 24.7% (95% CI 19.0-30.0) in the SG group, with an adjusted hazard ratio (HR) of 0.77 (95% CI 0.60-0.98, P = 0.04). Of the six individual end points, RYGB was associated with a significantly lower cumulative incidence of nephropathy at 5 years compared with SG (2.8% vs. 8.3%, respectively; HR 0.47 [95% CI 0.28-0.79], P = 0.005). Furthermore, RYGB was associated with a greater reduction in body weight, glycated hemoglobin, and use of medications to treat diabetes and cardiovascular diseases. Five years after RYGB, patients required more upper endoscopy (45.8% vs. 35.6%, P < 0.001) and abdominal surgical procedures (10.8% vs. 5.4%, P = 0.001) compared with SG.

CONCLUSIONS

In patients with obesity and T2DM, RYGB may be associated with greater weight loss, better diabetes control, and lower risk of MACE and nephropathy compared with SG.

Foregut Exclusion Enhances Incretin and Insulin Secretion After Roux-en-Y Gastric Bypass in Adults With Type 2 Diabetes

INTRODUCTION

Patients with type 2 diabetes experience resolution of hyperglycemia within days after Roux-en-Y gastric bypass (RYGB) surgery. This is attributed, in part, to enhanced secretion of hindgut factors following exclusion of the gastric remnant and proximal intestine during surgery. However, evidence of the mechanisms of remission remain limited due to the challenges of metabolic evaluation during the early postoperative period. The purpose of this investigation was to determine the role of foregut exclusion in the resolution of type 2 diabetes after RYGB.

METHODS

Patients with type 2 diabetes (n = 15) undergoing RYGB had a gastrostomy tube (G-tube) placed in their gastric remnant at time of surgery. Patients were randomized to receive a mixed meal tolerance test via oral or G-tube feeding immediately prior to and 2 weeks after surgery in a repeated measures crossover design. Plasma glucose, insulin, C-peptide, incretin responses, and indices of meal-stimulated insulin secretion and sensitivity were determined.

RESULTS

Body weight, fat mass, fasting glucose and insulin, and circulating lipids were significantly decreased 2 weeks after surgery. The glycemic response to feeding was reduced as a function of total area under the curve but not after adjustment for the reduction in fasting glucose. Oral feeding significantly enhanced insulin and incretin secretion after RYGB, which was entirely ablated by G-tube feeding.

CONCLUSION

Foregut exclusion accounts for the rise in incretin and insulin secretion but may not fully explain the early improvements in glucose metabolism after RYGB surgery.

Patient-reported Outcomes After Metabolic Surgery Versus Medical Therapy for Diabetes: Insights From the STAMPEDE Randomized Trial

OBJECTIVE

The aim of this study was to investigate the long-term effects of medical and surgical treatments of type 2 diabetes mellitus (T2DM) on patient-reported outcomes (PROs).

BACKGROUND

Robust data on PROs from randomized trials comparing medical and surgical treatments for T2DM are lacking.

METHODS

The Surgical Treatment And Medications Potentially Eradicate Diabetes Efficiently (STAMPEDE) trial showed that 5 years after randomization, Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) were superior to intensive medical therapy (IMT) alone in achieving glycemic control in patients with T2DM and obesity. A subset of 104 patients participating in the STAMPEDE trial were administered two generic health-related quality of life (QoL) questionnaires (RAND-36 and EQ-5D-3L) and a diabetes-specific instrument at baseline, and then on an annual basis up to 5 years after randomization.

RESULTS

On longitudinal analysis, RYGB and SG significantly improved the domains of physical functioning, general health perception, energy/fatigue, and diabetes-related QoL compared with IMT group. In the IMT group, none of the QoL components in the generic questionnaires improved significantly from baseline. No significant long-term differences were observed among the study groups in measures of psychological and social aspects of QoL. On multivariable analysis, independent factors associated with improved general health perception at long-term included baseline general health (P < 0.001), insulin independence at 5 years (P = 0.005), RYGB versus IMT (P = 0.005), and SG versus IMT (P = 0.034). Favorable changes following RYGB and SG were comparable.

CONCLUSIONS

In patients with T2DM, metabolic surgery is associated with long-term favorable changes in certain PROs compared with IMT, mainly on physical health and diabetes-related domains. Psychosocial well-being warrants greater attention after metabolic surgery.

Metabolic effects of duodenojejunal bypass surgery in a rat model of type 1 diabetes

BACKGROUND

Metabolic surgery has beneficial metabolic effects, including remission of type 2 diabetes. We hypothesized that duodenojejunal bypass (DJB) surgery can protect against development of type 1 diabetes (T1D) by enhancing regulation of cellular and molecular pathways that control glucose homeostasis.

METHODS

BBDP/Wor rats, which are prone to develop spontaneous autoimmune T1D, underwent loop DJB (n = 15) or sham (n = 15) surgery at a median age of 41 days, before development of diabetes. At T1D diagnosis, a subcutaneous insulin pellet was implanted, oral glucose tolerance test was performed 21 days later, and tissues were collected 25 days after onset of T1D. Pancreas and liver tissues were assessed by histology and RT-qPCR. Fecal microbiota composition was analyzed by 16S V4 sequencing.

RESULTS

Postoperatively, DJB rats weighed less than sham rats (287.8 vs 329.9 g, P = 0.04). In both groups, 14 of 15 rats developed T1D, at similar age of onset (87 days in DJB vs 81 days in sham, P = 0.17). There was no difference in oral glucose tolerance, fasting and stimulated plasma insulin and c-peptide levels, and immunohistochemical analysis of insulin-positive cells in the pancreas. DJB rats needed 1.3 ± 0.4 insulin implants vs 1.9 ± 0.5 in sham rats (P = 0.002). Fasting and glucose stimulated glucagon-like peptide 1 (GLP-1) secretion was elevated after DJB surgery. DJB rats had reduced markers of metabolic stress in liver. After DJB, the fecal microbiome changed significantly, including increases in Akkermansia and Ruminococcus, while the changes were minimal in sham rats.

CONCLUSION

DJB does not protect against autoimmune T1D in BBDP/Wor rats, but reduces the need for exogenous insulin and facilitates other metabolic benefits including weight loss, increased GLP-1 secretion, reduced hepatic stress, and altered gut microbiome.

Gastroesophageal Reflux After Sleeve Gastrectomy

Sleeve gastrectomy continues to be the most commonly performed bariatric operation worldwide. Development or worsening of pre-existing GERD has been recognized as a significant issue postoperatively. There is a paucity of information concerning the most appropriate preoperative workup and the technical and anatomical factors that may or may not contribute to the occurrence of reflux symptoms. Contemporary data quality is deficient given the predominantly retrospective nature, limited follow-up time, and heterogeneous outcome measures across studies. This has produced mixed results regarding the postoperative incidence and severity of GERD. Ultimately, better-constructed investigations are needed in order to offer evidence-based recommendations that may guide preoperative workup and improved patient selection criteria.

Roux-en-Y gastric bypass restores islet function and morphology independent of body weight in ZDF rats

Reductions in β-cell number and function contribute to the onset type 2 diabetes (T2D). Roux-en-Y gastric bypass (RYGB) surgery can resolve T2D within days of operation, indicating a weight-independent mechanism of glycemic control. We hypothesized that RYGB normalizes glucose homeostasis by restoring β-cell structure and function. Male Zucker Diabetic Fatty (fa/fa; ZDF) rats were randomized to sham surgery (n = 16), RYGB surgery (n = 16), or pair feeding (n = 16). Age-matched lean (fa/+) rats (n = 8) were included as a secondary control. Postprandial metabolism was assessed by oral glucose tolerance testing before and 27 days after surgery. Fasting and postprandial plasma GLP-1 was determined by mixed meal tolerance testing. Fasting plasma glucagon was also measured. β-cell function was determined in isolated islets by a glucose-stimulated insulin secretion assay. Insulin and glucagon positive areas were evaluated in pancreatic sections by immunohistochemistry. RYGB reduced body weight (P < 0.05) and improved glucose tolerance (P < 0.05) compared with sham surgery. RYGB reduced fasting glucose compared with both sham (P < 0.01) and pair-fed controls (P < 0.01). Postprandial GLP-1 (P < 0.05) was elevated after RYGB compared with sham surgery. RYGB islets stimulated with 20 mM glucose had higher insulin secretion than both sham and pair-fed controls (P < 0.01) and did not differ from lean controls. Insulin content was greater after RYGB compared with the sham (P < 0.05) and pair-fed (P < 0.05) controls. RYGB improves insulin secretion and pancreatic islet function, which may contribute to the remission of type 2 diabetes following bariatric surgery.NEW & NOTEWORTHY The onset and progression of type 2 diabetes (T2D) results from failure to secrete sufficient amounts of insulin to overcome peripheral insulin resistance. Here, we demonstrate that Roux-en-Y gastric bypass (RYGB) restores islet function and morphology compared to sham and pair-fed controls in ZDF rats. The improvements in islet function were largely attributable to enhanced insulin content and secretory function in response to glucose stimulation.

Effects of gastric bypass surgery on expression of glucose transporters and fibrotic biomarkers in kidney of diabetic fatty rats

BACKGROUND

Diabetic nephropathy is the leading cause of chronic kidney disease. Observational studies suggest Roux-en-Y gastric bypass (RYGB) reduces progression of diabetic nephropathy.

OBJECTIVES

To unravel the mechanisms by which RYGB is beneficial and protective for diabetic nephropathy.

SETTING

Academic laboratories.

METHODS

Forty-eight Zucker diabetic fatty rats were randomized to RYGB, sham surgery (SHAM), or pair-fed (PF) groups. An oral glucose tolerance test was performed at 25 days post intervention and kidneys were harvested at 30 days. Primary outcome measures included expression of key genes and proteins in the glucose transport, oxidative stress, inflammation, and fibrosis pathways.

RESULTS

Thirty days post intervention, RYGB rats weighed 349 ± 8 g, which was lower than SHAM (436 ± 14 g, P < .001), but not PF (374 ± 18 g) rats. RYGB rats had lower fasting glucose than PF animals and improved homeostatic model assessment of insulin resistance compared with PF and SHAM groups. These enhanced metabolic outcomes were accompanied by reduced sodium-glucose co-transporter 1 (Sglt1) gene expression (-23% versus PF, P = .01) in the kidney of RYGB rats. Expression of Sglt2, Glut1, or Glut2 mRNA, or oxidative stress and inflammation markers did not differ significantly. However, RYGB surgery induced a 19% lower expression of transforming growth factor (Tgfβ) mRNA (P = .004) compared with SHAM treated animals. Notably, adenosine monophosphate-activated protein kinase phosphorylation was increased (P = .04) in kidneys of the RYGB surgery animals.

CONCLUSIONS

Improvement of hyperglycemia after RYGB may reduce the glucose load on the kidney leading to a downregulation of specific glucose transporters. RYGB surgery may also attenuate kidney fibrosis through the adenosine monophosphate-activated protein kinase/TGFβ pathway.

Assessment of empiric body mass index-based thromboprophylactic dosing of enoxaparin after bariatric surgery: evidence for dosage adjustment using anti-factor Xa in high-risk patients

BACKGROUND

Despite thromboprophylaxis, postoperative deep vein thrombosis and pulmonary embolism occur after bariatric surgery, perhaps because of failure to achieve optimal prophylactic levels in the obese population.

OBJECTIVES

The aim of this study was to evaluate the adequacy of prophylactic dosing of enoxaparin in patients with severe obesity by performing an antifactor Xa (AFXa) assay.

SETTING

An academic medical center METHODS: In this observational study, all bariatric surgery cases at an academic center between December 2016 and April 2017 who empirically received prophylactic enoxaparin (adjusted by body mass index [BMI] threshold of 50 kg/m²) were studied. The AFXa was measured 3-5 hours after the second dose of enoxaparin.

RESULTS

A total of 105 patients were included; 85% were female with a median age of 47 years. In total, 16 patients (15.2%) had AFXa levels outside the prophylactic range: 4 (3.8%) cases were in the subprophylactic and 12 (11.4%) cases were in the supraprophylactic range. Seventy patients had a BMI <50 kg/m² and empirically received enoxaparin 40 mg every 12 hours; AFXa was subprophylactic in 4 (5.7%) and supraprophylactic in 6 (8.6%) of these patients. Of the 35 patients with a BMI ≥50 who empirically received enoxaparin 60 mg q12h, no AFXa was subprophylactic and 6 (17.1%) were supraprophylactic. Five patients (4.8%) had major bleeding complications. One patient developed pulmonary embolism on postoperative day 35.

CONCLUSION

BMI-based thromboprophylactic dosing of enoxaparin after bariatric surgery could be suboptimal in 15% of patients with obesity. Overdosing of prophylactic enoxaparin can occur more commonly than underdosing. AFXa testing can be a practical way to measure adequacy of pharmacologic thromboprophylaxis, especially in patients who are at higher risk for venous thromboembolism or bleeding.

Gastric Bypass Surgery Improves the Skeletal Muscle Ceramide/S1P Ratio and Upregulates the AMPK/ SIRT1/ PGC-1α Pathway in Zucker Diabetic Fatty Rats

PURPOSE

Roux-en-Y gastric bypass (RYGB) is associated with remission of type 2 diabetes. However, the cellular and molecular mechanisms remain unknown. We hypothesized that RYGB would increase peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), sirtuin-1 (SIRT1), AMPK/pAMPK, and citrate synthase (CS) protein expression and decrease insulin resistance and these changes would be mediated by sphingolipids, including ceramides and the sphingolipid metabolite sphingosine-1 phosphate (S1P).

MATERIALS AND METHODS

Male ZDF rats were randomized to RYGB (n = 7) or sham surgery (n = 7) and harvested after 28 days. Total tissue ceramide, ceramide subspecies (C14:0, C16:0, C18:0, C18:1, C20:0, C24:0, and C24:1), and S1P were quantified in the white gastrocnemius muscle using LC-ESI-MS/MS after separation with HPLC. Total SIRT1, AMPK, PGC-1α, and CS protein expression were measured by Western blot.

RESULTS

Body weight, fasting glucose, insulin, and HOMA-IR decreased significantly after RYGB compared with sham control. These changes were paralleled by lower total ceramide (483.7 ± 32.3 vs. 280.1 ± 38.8 nmol/g wwt), C18:0 ceramide subspecies (P < 0.05), higher S1P (0.83 ± 0.05 vs. 1.54 ± 0.21 nmol/g wwt, P < 0.05), and a lower ceramide/S1P ratio (P < 0.05) in the RYGB versus sham group. AMPK, pAMPK, SIRT1, PGC-1α, and CS protein expression was also higher after RYGB (P < 0.05). The ceramide/S1P ratio correlated with weight loss (r = 0.48, P = 0.08), insulin resistance (r = 0.61, P = 0.02), PGC-1α (r = - 0.51, P < 0.06), CS (r = - 0.63, P = 0.01), and SIRT1 (r = - 0.54, P < 0.04).

CONCLUSION

Our data demonstrate that sphingolipid balance, and increased AMPK, SIRT1, PGC-1α, and CS protein expression are part of the mechanism that contributes to the remission of diabetes after RYGB surgery.

Predicting 10-Year Risk of End-Organ Complications of Type 2 Diabetes With and Without Metabolic Surgery: A Machine Learning Approach

OBJECTIVE

To construct and internally validate prediction models to estimate the risk of long-term end-organ complications and mortality in patients with type 2 diabetes and obesity that can be used to inform treatment decisions for patients and practitioners who are considering metabolic surgery.

RESEARCH DESIGN AND METHODS

A total of 2,287 patients with type 2 diabetes who underwent metabolic surgery between 1998 and 2017 in the Cleveland Clinic Health System were propensity-matched 1:5 to 11,435 nonsurgical patients with BMI ≥30 kg/m2 and type 2 diabetes who received usual care with follow-up through December 2018. Multivariable time-to-event regression and random forest machine learning models were built and internally validated using fivefold cross-validation to predict the 10-year risk for four outcomes of interest. The prediction models were programmed to construct user-friendly web-based and smartphone applications of Individualized Diabetes Complications (IDC) Risk Scores for clinical use.

RESULTS

The prediction tools demonstrated the following discrimination ability based on the area under the receiver operating characteristic curve (1 = perfect discrimination and 0.5 = chance) at 10 years in the surgical and nonsurgical groups, respectively: all-cause mortality (0.79 and 0.81), coronary artery events (0.66 and 0.67), heart failure (0.73 and 0.75), and nephropathy (0.73 and 0.76). When a patient's data are entered into the IDC application, it estimates the individualized 10-year morbidity and mortality risks with and without undergoing metabolic surgery.

CONCLUSIONS

The IDC Risk Scores can provide personalized evidence-based risk information for patients with type 2 diabetes and obesity about future cardiovascular outcomes and mortality with and without metabolic surgery based on their current status of obesity, diabetes, and related cardiometabolic conditions.

Late Relapse of Diabetes After Bariatric Surgery: Not Rare, but Not a Failure

OBJECTIVE

To characterize the status of cardiometabolic risk factors after late relapse of type 2 diabetes mellitus (T2DM) and to identify factors predicting relapse after initial diabetes remission following bariatric surgery to construct prediction models for clinical practice.

RESEARCH DESIGN AND METHODS

Outcomes of 736 patients with T2DM who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) at an academic center (2004-2012) and had ≥5 years' glycemic follow-up were assessed. Of 736 patients, 425 (58%) experienced diabetes remission (HbA_1c <6.5% [48 mmol/mol] with patients off medications) in the 1st year after surgery. These 425 patients were followed for a median of 8 years (range 5-14) to characterize late relapse of diabetes.

RESULTS

In 136 (32%) patients who experienced late relapse, a statistically significant improvement in glycemic control, number of diabetes medications including insulin use, blood pressure, and lipid profile was still observed at long-term. Independent baseline predictors of late relapse were preoperative number of diabetes medications, duration of T2DM before surgery, and SG versus RYGB. Furthermore, patients who relapsed lost less weight during the 1st year after surgery and regained more weight afterward. Prediction models were constructed and externally validated.

CONCLUSIONS

While late relapse of T2DM is a real phenomenon (one-third of our cohort), it should not be considered a failure, as the trajectory of the disease and its related cardiometabolic risk factors is changed favorably after bariatric surgery. Earlier surgical intervention, RYGB (compared with SG) and more weight loss (less late weight regain) are associated with less diabetes relapse in the long-term.

Redesigning a Department of Surgery during the COVID-19 Pandemic

BACKGROUND

COVID-19 has created an urgent need for reorganization and surge planning among departments of surgery across the USA.

METHODS

Review of the COVID-19 planning process and work products in preparation for a patient surge. Organizational and process changes, workflow redesign, and communication plans are presented.

RESULTS

The planning process included widespread collaboration among leadership from many disciplines. The department of surgery played a leading role in establishing clinical protocols, guidelines, and policies in preparation for a surge of COVID-19 patients. A multidisciplinary approach with input from clinical and nonclinical stakeholders is critical to successful crisis planning. A clear communication plan should be implemented early and input from trainees, staff, and faculty should be solicited.

CONCLUSION

Major departmental and health system reorganization is required to adapt academic surgical practices to a widespread crisis. Surgical leadership, innovation, and flexibility are critical to successful planning and implementation.

The Outcome of Bariatric Surgery in Patients Aged 75 years and Older

BACKGROUND

Bariatric surgery has been shown to be safe and effective in patients aged 60-75 years; however, outcomes in patients aged 75 or older are undocumented.

METHODS

Patients aged 75 years and older who underwent bariatric procedures in two academic centers between 2006 and 2015 were studied.

RESULTS

A total of 19 patients aged 75 years and above were identified. Eleven (58%) were male, the median age was 76 years old (range 75-81), and the median preoperative body mass index (BMI) was 41.4 kg/m² (range 35.8-57.5). All of the bariatric procedures were primary procedures and performed laparoscopically: sleeve gastrectomy (SG) (n = 11, 58%), adjustable gastric band (AGB) (n = 4, 21%), Roux-en-Y gastric bypass (RYGB) (n = 2, 11%), banded gastric plication (n = 1, 5%), and gastric plication (n = 1, 5%). The median operative time was 120 min (range 75-240), and the median length of stay was 2 days (range 1-7). Three patients (16%) developed postoperative atrial fibrillation which completely resolved at discharge. At 1 year, the median percentage of total weight loss (%TWL) was 18.4% (range 7.4-22.0). The 1-year %TWL varied among the bariatric procedures performed: SG (21%), RYGB (22%), AGB (7%), and gastric plication (8%). There were no 30-day readmissions, reoperations, or mortalities.

CONCLUSION

Our experience suggests that bariatric surgery in selected patients aged 75 years and older would be safe and effective despite being higher risk. Age alone should not be the limiting factor for selecting patients for bariatric surgery.

Association of Metabolic Surgery With Major Adverse Cardiovascular Outcomes in Patients With Type 2 Diabetes and Obesity

IMPORTANCE

Although metabolic surgery (defined as procedures that influence metabolism by inducing weight loss and altering gastrointestinal physiology) significantly improves cardiometabolic risk factors, the effect on cardiovascular outcomes has been less well characterized.

OBJECTIVE

To investigate the relationship between metabolic surgery and incident major adverse cardiovascular events (MACE) in patients with type 2 diabetes and obesity.

DESIGN, SETTING, AND PARTICIPANTS

Of 287 438 adult patients with diabetes in the Cleveland Clinic Health System in the United States between 1998 and 2017, 2287 patients underwent metabolic surgery. In this retrospective cohort study, these patients were matched 1:5 to nonsurgical patients with diabetes and obesity (body mass index [BMI] ≥30), resulting in 11 435 control patients, with follow-up through December 2018.

EXPOSURES

Metabolic gastrointestinal surgical procedures vs usual care for type 2 diabetes and obesity.

MAIN OUTCOMES AND MEASURES

The primary outcome was the incidence of extended MACE (composite of 6 outcomes), defined as first occurrence of all-cause mortality, coronary artery events, cerebrovascular events, heart failure, nephropathy, and atrial fibrillation. Secondary end points included 3-component MACE (myocardial infarction, ischemic stroke, and mortality) and the 6 individual components of the primary end point.

RESULTS

Among the 13 722 study participants, the distribution of baseline covariates was balanced between the surgical group and the nonsurgical group, including female sex (65.5% vs 64.2%), median age (52.5 vs 54.8 years), BMI (45.1 vs 42.6), and glycated hemoglobin level (7.1% vs 7.1%). The overall median follow-up duration was 3.9 years (interquartile range, 1.9-6.1 years). At the end of the study period, 385 patients in the surgical group and 3243 patients in the nonsurgical group experienced a primary end point (cumulative incidence at 8-years, 30.8% [95% CI, 27.6%-34.0%] in the surgical group and 47.7% [95% CI, 46.1%-49.2%] in the nonsurgical group [P < .001]; absolute 8-year risk difference [ARD], 16.9% [95% CI, 13.1%-20.4%]; adjusted hazard ratio [HR], 0.61 [95% CI, 0.55-0.69]). All 7 prespecified secondary outcomes showed statistically significant differences in favor of metabolic surgery, including mortality. All-cause mortality occurred in 112 patients in the metabolic surgery group and 1111 patients in the nonsurgical group (cumulative incidence at 8 years, 10.0% [95% CI, 7.8%-12.2%] and 17.8% [95% CI, 16.6%-19.0%]; ARD, 7.8% [95% CI, 5.1%-10.2%]; adjusted HR, 0.59 [95% CI, 0.48-0.72]).

CONCLUSIONS AND RELEVANCE

Among patients with type 2 diabetes and obesity, metabolic surgery, compared with nonsurgical management, was associated with a significantly lower risk of incident MACE. The findings from this observational study must be confirmed in randomized clinical trials.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03955952.

Bariatric Surgery in Patients on Chronic Anticoagulation Therapy

BACKGROUND

Perioperative management of chronically anti-coagulated patients undergoing bariatric surgery requires a balance of managing hemorrhagic and thromboembolic risks. The aim of this study is to evaluate the incidence of hemorrhagic complications and their management in chronically anticoagulated (CAT) patients undergoing bariatric surgery.

METHODS

A retrospective review of CAT patients undergoing bariatric surgery at an academic center from 2008 to 2015 was studied.

RESULTS

A total of 153 patients on CAT underwent surgery [Roux-en-Y gastric bypass (n = 79), sleeve gastrectomy (n = 63), and adjustable gastric banding (n = 11)] during the study period: 85 patients (55%) were females; median age was 56 years (interquartile range [IQR] 49-64), and median BMI was 49 kg/m² (IQR 43-56). The most common indications for CAT were venous thromboembolism (n = 87) and atrial fibrillation (n = 83). Median duration of procedure and estimated intraoperative blood loss was 150 min (IQR 118-177) and 50 ml (IQR 25-75), respectively. Thirty-day postoperative complications were reported in 33 patients (21.6%) including postoperative bleeding (n = 19), anastomotic leak (n = 3), and pulmonary embolism (n = 1). Nineteen patients (12%) with early postoperative bleeding were further categorized to intra-abdominal (n = 10), intraluminal (n = 6), and at the port site or abdominal wall (n = 3). All-cause readmissions within 30 days of surgery occurred in 19 patients (12%). There was no 30-day mortality.

CONCLUSION

In our experience, patients who require chronic anticoagulation medication are higher than average risk for postoperative complications and all-cause readmission rates. Careful surgical technique and close attention to postoperative anticoagulation protocols are essential to decrease perioperative risk in this high-risk cohort.

Bariatric surgery is associated with a lower rate of death after myocardial infarction and stroke: A nationwide study

AIM

To assess the potential protective effect of bariatric surgery on mortality after myocardial infarction (MI) or cerebrovascular accident (CVA).

MATERIALS AND METHODS

Using the National Inpatient Sample (2007-2014), 2218 patients with a principal discharge diagnosis of acute MI and 2168 patients with ischaemic CVA who also had history of prior bariatric surgery were identified. Utilizing propensity scores, these patients were matched 1:5 with patients who had similar principal diagnoses but no history of bariatric surgery (controls). Control group-1 included participants with obesity (BMI ≥ 35 kg/m² ) only and participants in control group-2 were matched according to post-surgery BMI with the bariatric surgery group. The primary and secondary endpoints were in-hospital all-cause mortality and length of hospital stay, respectively. Outcomes after MI and CVA were separately compared among groups in multivariate regression models.

RESULTS

A total of 48 300 (weighted) participants were included in the analysis. The distribution of covariates was well balanced after propensity matching. Mortality rates after MI were significantly lower in patients with a history of bariatric surgery compared with control group-1 (1.85% vs 3.03%; odds ratio (OR), 0.61; 95% confidence interval (CI), 0.44-0.86; P = 0.004) and with control group-2 (2.00% vs 3.26%; OR, 0.62; 95% CI, 0.44-0.88; P = 0.008). Similarly, in-hospital mortality rates after CVA were significantly lower in patients with a history of bariatric surgery compared with control group-1 (1.43% vs 2.74%; OR, 0.54; 95% CI, 0.37-0.79; P = 0.001) and with control group-2 (1.54% vs 2.59%; OR, 0.61; 95% CI, 0.41-0.91; P = 0.015). Furthermore, length of stay was significantly shorter in the bariatric surgery group for all comparisons (P < 0.001).

CONCLUSION

Prior bariatric surgery is associated with significant protective effect on survival after MI and CVA.

Impact of bariatric surgery on heart failure mortality

BACKGROUND

The impact of bariatric surgery on discrete cardiovascular events has not been well characterized.

OBJECTIVES

To assess the impact of prior bariatric surgery on mortality associated with heart failure (HF) admission.

SETTING

A retrospective analysis of 2007-2014 Healthcare Cost and Utilization Project-Nationwide Inpatient Sample.

METHODS

Participants including 2810 patients with a principal discharge diagnosis of HF who also had a history of prior bariatric surgery were identified. These patients were matched 1:5 with patients who had similar principal diagnoses but no history of bariatric surgery (controls). Propensity scores, balanced on baseline characteristics, were used to assemble 2 control groups. Control group-1 included patients with obesity (body mass index [BMI] ≥35 kg/m²) only. In control group-2, the BMI was considered as one of the matching criteria in propensity matching. Multivariate regression models were utilized to calculate the odds ratio (OR) and 95% confidence interval (CI) of mortality and length of stay (LOS).

RESULTS

With well-balanced matching, 33,720 (weighted) patients were included in the analysis. In-hospital mortality rates after HF admission were significantly lower in patients with a history of bariatric surgery compared with control group-1 (0.96% versus 1.86%, OR .52, 95% CI .35-0.77, P = .0013) and control group-2 (0.96% versus 1.86%, OR .52, 95% CI .35-0.77, P = .0011). Furthermore, LOS was shorter in the bariatric surgery group compared with control group-1 (4.8 ± 4.4 versus 5.7 ± 5.7 d, P < .001) and control group-2 (4.8 ± 4.4 versus 5.4 ± 6.3 d, P < .001).

CONCLUSIONS

Our data suggest that prior bariatric surgery is associated with almost 50% reduction in in-hospital mortality and shorter LOS in patients with HF admission.

Bariatric surgery in patients with interstitial lung disease

BACKGROUND

Perioperative pulmonary complications are frequent in patients with interstitial lung diseases (ILD). Limited literature exists regarding the safety of bariatric procedures in patients with ILD. This study aims to assess the safety, feasibility, and outcomes of patients with ILD who underwent bariatric surgery at our institution.

METHODS

After IRB approval, all patients with preoperative diagnosis of ILD who had bariatric surgery at an academic center between 2004 and 2014 were retrospectively reviewed.

RESULTS

A total of 25 patients with ILD underwent bariatric surgery: Roux-en-Y gastric bypass (n = 17, 68%), sleeve gastrectomy (n = 7, 28%), and adjustable gastric banding (n = 1, 4%). Twenty-one patients (84%) were females. The median age and preoperative body mass index (BMI) were 53 (IQR 42-58) years and 39 (IQR 37-44) kg/m², respectively. The median operative time and length of stay was 137 (IQR 110-187) min and 3 (IQR 2-5) days, respectively. The 30-day complications were reported in four patients (16%) but there was no pulmonary complication or unplanned admission to the intensive care unit. At 1-year follow-up (85%), the median BMI and excess weight loss were 30 (IQR 25-36) kg/m² and 67% (IQR 45-100), respectively. Compared to preoperative values, there was significant improvement in the pulmonary function test (PFT) variables at 1 year with respect to forced vital capacity (62% vs 74%; n = 13, p = 0.003), and diffusing capacity of the lungs for carbon monoxide (53% vs 66%; n = 10, p = 0.003). Six out of the seven potential lung transplant candidates became eligible for transplantation after weight loss, and one of them had successful lung transplant at 88 months after bariatric surgery.

CONCLUSION

In our experience, bariatric patients with ILD achieved significant weight loss and improvement in PFT. Bariatric surgery in these higher risk ILD patients appears relatively safe with acceptable perioperative morbidity and improved candidacy for lung transplantation.

Bariatric surgery in patients with pulmonary hypertension

BACKGROUND

Data regarding the outcomes of bariatric surgery in patients with pulmonary hypertension (PH) is limited. The aim of this study was to review our experience on bariatric surgery in patients with PH.

SETTING

An academic medical center.

METHODS

Patients with PH who underwent either a primary or revisional bariatric surgery between 2005 and 2015 and had a preoperative right ventricle systolic pressure (RVSP) ≥35 mm Hg were included.

RESULTS

Sixty-one patients met the inclusion criteria. Fifty (82%) were female with the median age of 58 years (interquartile range [IQR] 49-63). The median body mass index was 49 kg/m² (IQR 43-54). Procedures performed included the following: Roux-en-Y gastric bypass (n = 33, 54%), sleeve gastrectomy (n = 24, 39%), adjustable gastric banding (n = 3, 5%), and banded gastric plication (n = 1, 2%). Four patients (7%) underwent revisional bariatric procedures. Median operative time and length of stay was 130 minutes (IQR 110-186) and 3 days (IQR 2-5), respectively. The 30-day complication rate was 16% (n = 10) with pulmonary complications noted in 4 patients. There was no 30-day mortality. One-year follow-up was available in 93% patients (n = 57). At 1 year, median body mass index and excess weight loss were 36 kg/m² (IQR 33-41) and 51% (IQR 33-68), respectively. There was significant improvement in the RVSP after bariatric surgery at a median follow-up of 22 months (IQR 10-41). The median RVSP decreased from 44 (IQR 38-53) to 40 mm Hg (IQR 28-54) (P = .03).

CONCLUSION

Bariatric surgery can be performed without prohibitive complication rates in patients with PH. In our experience, bariatric patients with PH achieved significant weight loss and improvement in RVSP.

Neurologic Manifestations of Vitamin B Deficiency after Bariatric Surgery

INTRODUCTION

The aim of this study was to assess the incidence, clinical presentation, and outcomes of neurologic disorders secondary to vitamin B deficiencies following bariatric surgery.

METHODS

Patients at a single academic institution who underwent bariatric surgery and developed neurologic complications secondary to low levels of vitamins B1, B2, B6, and B12 between the years 2004 and 2015 were studied.

RESULTS

In total, 47 (0.7%) bariatric surgical patients (Roux-en-Y gastric bypass n = 36, sleeve gastrectomy n = 9, and duodenal switch n = 2) developed neurologic manifestations secondary to vitamin B deficiencies. Eleven (23%) patients developed postoperative anatomical complications contributed to poor oral intake. Median duration to onset of neurologic manifestation following surgery was 12 months (IQR, 5-32). Vitamin deficiencies reported in the cohort included B1 (n = 30), B2 (n = 1), B6 (n = 12), and B12 (n = 12) deficiency. The most common manifestations were paresthesia (n = 31), muscle weakness (n = 15), abnormal gait (n = 11), and polyneuropathy (n = 7). Four patients were diagnosed with Wernicke-Korsakoff syndrome (WKS) which was developed after gastric bypass (n = 3) and sleeve gastrectomy (n = 1). Seven patients required readmission for management of severe vitamin B deficiencies. Overall, resolution of neurologic symptoms with nutritional interventions and pharmacotherapy was noted in 40 patients (85%). The WKS was not reversible, and all four patients had residual mild ataxia and nystagmus at the last follow-up time.

CONCLUSIONS

Nutritional neurologic disorders secondary to vitamin B deficiency are relatively uncommon after bariatric surgery. While neurologic disorders are reversible in most patients (85%) with vitamin replacements, persistent residual neurologic symptoms are common in patients with WKS.

The Utility of Diagnostic Laparoscopy in Post-Bariatric Surgery Patients with Chronic Abdominal Pain of Unknown Etiology

PURPOSE

Chronic abdominal pain after bariatric surgery is associated with diagnostic and therapeutic challenges. The aim of this study was to evaluate the yield of laparoscopy as a diagnostic and therapeutic tool in post-bariatric surgery patients with chronic abdominal pain who had negative imaging and endoscopic studies.

METHODS

A retrospective analysis was performed on post-bariatric surgery patients who underwent laparoscopy for diagnosis and treatment of chronic abdominal pain at a single academic center. Only patients with both negative preoperative CT scan and upper endoscopy were included.

RESULTS

Total of 35 post-bariatric surgery patients met the inclusion criteria, and all had history of Roux-en-Y gastric bypass. Twenty out of 35 patients (57%) had positive findings on diagnostic laparoscopy including presence of adhesions (n = 12), chronic cholecystitis (n = 4), mesenteric defect (n = 2), internal hernia (n = 1), and necrotic omentum (n = 1). Two patients developed post-operative complications including a pelvic abscess and an abdominal wall abscess. Overall, 15 patients (43%) had symptomatic improvement after laparoscopy; 14 of these patients had positive laparoscopic findings requiring intervention (70% of the patients with positive laparoscopy). Conversely, 20 (57%) patients required long-term medical treatment for management of chronic abdominal pain.

CONCLUSION

Diagnostic laparoscopy, which is a safe procedure, can detect pathological findings in more than half of post-bariatric surgery patients with chronic abdominal pain of unknown etiology. About 40% of patients who undergo diagnostic laparoscopy and 70% of patients with positive findings on laparoscopy experience significant symptom improvement. Patients should be informed that diagnostic laparoscopy is associated with no symptom improvement in about half of cases.

Effect of Roux-en-Y gastric bypass on liver mitochondrial dynamics in a rat model of obesity

Bariatric surgery provides significant and durable improvements in glycemic control and hepatic steatosis, but the underlying mechanisms that drive improvements in these metabolic parameters remain to be fully elucidated. Recently, alterations in mitochondrial morphology have shown a direct link to nutrient adaptations in obesity. Here, we evaluate the effects of Roux-en-Y gastric bypass (RYGB) surgery on markers of liver mitochondrial dynamics in a diet-induced obesity Sprague-Dawley (SD) rat model. Livers were harvested from adult male SD rats 90-days after either Sham or RYGB surgery and continuous high-fat feeding. We assessed expression of mitochondrial proteins involved in fusion, fission, mitochondrial autophagy (mitophagy) and biogenesis, as well as differences in citrate synthase activity and markers of oxidative stress. Gene expression for mitochondrial fusion genes, mitofusin 1 (Mfn1; P < 0.05), mitofusin 2 (Mfn2; P < 0.01), and optic atrophy 1 (OPA1; P < 0.05) increased following RYGB surgery. Biogenesis regulators, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α; P < 0.01) and nuclear respiratory factor 1 (Nrf1; P < 0.05), also increased in the RYGB group, as well as mitophagy marker, BCL-2 interacting protein 3 (Bnip3; P < 0.01). Protein expression for Mfn1 (P < 0.001), PGC1α (P < 0.05), BNIP3 (P < 0.0001), and mitochondrial complexes I-V (P < 0.01) was also increased by RYGB, and Mfn1 expression negatively correlated with body weight, insulin resistance, and fasting plasma insulin. In the RYGB group, citrate synthase activity was increased (P < 0.02) and reactive oxygen species (ROS) was decreased compared to the Sham control group (P < 0.05), although total antioxidant capacity was unchanged between groups. These data are the first to show an association between RYGB surgery and improved markers of liver mitochondrial dynamics. These observed improvements may be related to weight loss and reduced energetic demand on the liver, which could facilitate normalization of glucose homeostasis and protect against hepatic steatosis.