Bile salt hydrolase acyltransferase activity expands bile acid diversity.

Bile acids (BAs) are steroid detergents in bile that contribute to the absorption of fats and fat-soluble vitamins while shaping the gut microbiome because of their antimicrobial properties1-4. Here we identify the enzyme responsible for a mechanism of BA metabolism by the gut microbiota involving amino acid conjugation to the acyl-site of BAs, thus producing a diverse suite of microbially conjugated bile acids (MCBAs). We show that this transformation is mediated by acyltransferase activity of bile salt hydrolase (bile salt hydrolase/transferase, BSH/T). Clostridium perfringens BSH/T rapidly performed acyl transfer when provided various amino acids and taurocholate, glycocholate or cholate, with an optimum at pH 5.3. Amino acid conjugation by C. perfringens BSH/T was diverse, including all proteinaceous amino acids except proline and aspartate. MCBA production was widespread among gut bacteria, with strain-specific amino acid use. Species with similar BSH/T amino acid sequences had similar conjugation profiles and several bsh/t alleles correlated with increased conjugation diversity. Tertiary structure mapping of BSH/T followed by mutagenesis experiments showed that active site structure affects amino acid selectivity. These MCBA products had antimicrobial properties, where greater amino acid hydrophobicity showed greater antimicrobial activity. Inhibitory concentrations of MCBAs reached those measured natively in the mammalian gut. MCBAs fed to mice entered enterohepatic circulation, in which liver and gallbladder concentrations varied depending on the conjugated amino acid. Quantifying MCBAs in human faecal samples showed that they reach concentrations equal to or greater than secondary and primary BAs and were reduced after bariatric surgery, thus supporting MCBAs as a significant component of the BA pool that can be altered by changes in gastrointestinal physiology. In conclusion, the inherent acyltransferase activity of BSH/T greatly diversifies BA chemistry, creating a set of previously underappreciated metabolites with the potential to affect the microbiome and human health.

Association of Metabolomic Biomarkers with Sleeve Gastrectomy Weight Loss Outcomes.

This prospective observational study aimed to evaluate the association of metabolomic alterations with weight loss outcomes following sleeve gastrectomy (SG). We evaluated the metabolomic profile of serum and feces prior to SG and three months post-SG, along with weight loss outcomes in 45 adults with obesity. The percent total weight loss for the highest versus the lowest weight loss tertiles (T3 vs. T1) was 17.0 ± 1.3% and 11.1 ± 0.8%, p < 0.001. Serum metabolite alterations specific to T3 at three months included a decrease in methionine sulfoxide concentration as well as alterations to tryptophan and methionine metabolism (p < 0.03). Fecal metabolite changes specific to T3 included a decrease in taurine concentration and perturbations to arachidonic acid metabolism, and taurine and hypotaurine metabolism (p < 0.002). Preoperative metabolites were found to be highly predictive of weight loss outcomes in machine learning algorithms, with an average area under the curve of 94.6% for serum and 93.4% for feces. This comprehensive metabolomics analysis of weight loss outcome differences post-SG highlights specific metabolic alterations as well as machine learning algorithms predictive of weight loss. These findings could contribute to the development of novel therapeutic targets to enhance weight loss outcomes after SG.

The effect of an attending versus neutral observer on peg transfer and intracorporeal knot-tying laparoscopic tasks.

BACKGROUND: Surgery is an outcome-based specialty where maintaining peak performance is crucial to patient care. There are a variety of identified surgeon stressors that can have an impact on performance, but one factor unique to surgical residents is the observation by an attending surgeon. This study explored how the perceived authority of the observer had an impact on the participants' physiologic markers of stress and task completion times. METHODS: Eighteen general surgery residents performed the Fundamentals of Laparoscopic Surgery skills intracorporeal knot-tying and peg transfer tasks in a crossover study design while under the observation of an attending and a neutral observer. Heart rate variability, mean R-R interval, the time between R spikes on an EKG, minimum heart rate, maximum heart rate, average heart rate, and time to task completion were recorded. Analyses were completed via 2 × 2 analysis of variance with repeated measures. RESULTS: When observed by an attending, participants demonstrated higher minimum, average, and maximum heart rates (P = .046, = .007, and < .001, respectively) than when observed by a neutral observer. Attending observation also significantly shortened time to task completion, relative to neutral observation (P = .022). CONCLUSION: Attending observation is linked to increased objective measures of stress at the time of performance with decreased task completion times. Educational efforts to optimize the response to stress during learning may lead to better outcomes.

High-risk bariatric candidates: does red-flagging predict the post-operative course?

BACKGROUND: Standards for preoperative bariatric patient selection include a thorough psychological evaluation. Using patients "red-flagged" during preoperative evaluations, this study aims to identify trends in long-term follow-up and complications to further optimize bariatric patient selection. METHODS: A multidisciplinary team held a case review conference (CRC) to discuss red-flagged patients. A retrospective chart review compared CRC patients to control patients who underwent bariatric surgery in the same interval. Patients under 18 years old, undergoing revisional bariatric surgery, or getting band placement were excluded. High-risk characteristics causing CRC inclusion, preoperative demographics, percent follow-up and other postoperative outcomes were collected up to 5 years postoperatively. If univariate analysis revealed a significant difference between cohorts, multivariable analysis was performed. RESULTS: Two hundred and fifty three patients were red-flagged from 2012 to 2013, of which 79 underwent surgery. After excluding 21 revisions, 3 non-adult patients, and 6 band patients, 55 red-flagged patients were analyzed in addition to 273 control patients. Patient age, sex, initial BMI, ASA, and co-morbidities were similar between groups, though flagged patients underwent RYGB more frequently than control patients. Notably, percent excess BMI loss and percent follow-up (6 months-5 years) were similar. In multivariable analysis, minor complications were more common in flagged patients; and marginal ulcers, endoscopy, and dilation for stenosis were more common in flagged versus control patients who underwent RYGB. Perforation, reoperation, revision, incisional hernia, and internal hernia were statistically similar in both groups, though reoperation was significantly more common in patients with multiple reasons to be flagged compared to controls. CONCLUSION: Bariatric patients deemed high risk for various psychosocial issues have similar follow-up, BMI loss, and major complications compared to controls. High-risk RYGB patients have greater minor complications, warranting additional counseling of high-risk patients.

Adipocytes enhance murine pancreatic cancer growth via a hepatocyte growth factor (HGF)-mediated mechanism.

INTRODUCTION: Obesity accelerates the development and progression of pancreatic cancer, though the mechanisms underlying this association are unclear. Adipocytes are biologically active, producing factors such as hepatocyte growth factor (HGF) that may influence tumor progression. We therefore sought to test the hypothesis that adipocyte-secreted factors including HGF accelerate pancreatic cancer cell proliferation. MATERIAL AND METHODS: Murine pancreatic cancer cells (Pan02 and TGP-47) were grown in a) conditioned medium (CM) from murine F442A preadipocytes, b) HGF-knockdown preadipocyte CM, c) recombinant murine HGF at increasing doses, and d) CM plus HGF-receptor (c-met) inhibitor. Cell proliferation was measured using the MTT assay. ANOVA and t-test were applied; p < 0.05 considered significant. RESULTS: Wild-type preadipocyte CM accelerated Pan02 and TGP-47 cell proliferation relative to control (59 ± 12% and 34 ± 12%, p < 0.01, respectively). Knockdown of preadipocyte HGF resulted in attenuated proliferation vs. wild type CM in Pan02 cells (35 ± 5% vs. 68 ± 14% greater than control; p < 0.05), but proliferation in TGP-47 cells remained unchanged. Recombinant HGF dose-dependently increased Pan02, but not TGP-47, proliferation (p < 0.05). Inhibition of HGF receptor, c-met, resulted in attenuated proliferation versus control in Pan02 cells, but not TGP-47 cells. CONCLUSIONS: These experiments demonstrate that adipocyte-derived factors accelerate murine pancreatic cancer proliferation. In the case of Pan02 cells, HGF is responsible, in part, for this proliferation.

Obesity, but not high-fat diet, promotes murine pancreatic cancer growth.

BACKGROUND: Obesity accelerates pancreatic cancer growth; the mechanisms underlying this association are poorly understood. This study evaluated the hypothesis that obesity, rather than high-fat diet, is responsible for accelerated pancreatic cancer growth. METHODS: Male C57BL/6J mice were studied after 19 weeks of high-fat (60 % fat; n = 20) or low-fat (10 % fat; n = 10) diet and 5 weeks of Pan02 murine pancreatic cancer growth (flank). RESULTS: By two-way ANOVA, diet did not (p = 0.58), but body weight, significantly influenced tumor weight (p = 0.01). Tumor weight correlated positively with body weight (R (2) = 0.562; p < 0.001). Tumors in overweight mice were twice as large as those growing in lean mice (1.2 ± 0.2 g vs. 0.6 ± .01 g, p < 0.01), had significantly fewer apoptotic cells than those in lean mice (0.8 ± 0.4 vs 2.4 ± 0.5; p < 0.05), and greater adipocyte volume (3.7 vs. 2.2 %, p < 0.05). Apoptosis (R (2) = 0.472; p = 0.008) and serum adiponectin correlated negatively with tumor weight (R = 0.45; p < 0.05). CONCLUSIONS: These data suggest that body weight, and not high-fat diet, is responsible for accelerated murine pancreatic cancer growth observed in this model of diet-induced obesity. Decreased tumor apoptosis appears to play an important mechanistic role in this process. The concept that decreased apoptosis is potentiated by hypoadiponectinemia (seen in obesity) deserves further investigation.

Choledochoceles: are they choledochal cysts?

The classification of choledochoceles as a type of choledochal cyst stems from the 1959 article by Alonso-Lej and colleagues describing 94 choledochal cysts, only 4 of which were choledochoceles. Even then, Alonso-Lej questioned the propriety of including the choledochocele, stating it was unclear "as to whether or not it originates from the same etiologic factors [as other choledochal cysts]". In 1971, Trout and Longmire also questioned the validity of classifying choledochoceles as choledochal cysts, noting the anatomic position article and variant mucosa of the choledochocele. Wearn and Wiot, in an article titled "Choledochocele: not a form of choledochal cyst", cite the differences in clinical presentation, demographics, and histology as reasons why choledochoceles represent separate entities from choledochal cysts. Over the ensuing decades, numerous investigators have questioned the legitimacy of classifying choledochoceles as choledochal cysts. In our recent series (the only one to our knowledge directly comparing patients with choledochocele and other [type I, II, IV, and V] choledochal cysts), patients with choledochoceles differed from patients with choledochal cysts in their age, gender, presenting symptoms, history of previous cholecystectomy, pancreatobiliary ductal anatomy, management, and most importantly, propensity to developing biliary malignancy. Based on the available cases of choledochoceles found in the literature, combined with the recent series from our institution, we conclude that choledochoceles seem to be distinct entities from choledochal cysts.

Does adiponectin upregulation attenuate the severity of acute pancreatitis in obesity?

INTRODUCTION: Obesity is an independent risk factor for severe acute pancreatitis, though the mechanisms underlying this association are unknown. The powerful anti-inflammatory adipokine adiponectin is decreased in obesity. We recently showed that the severity of pancreatitis in obese mice is inversely related to circulating adiponectin levels, and therefore hypothesized that adiponectin upregulation would attenuate the severity of pancreatitis in obese mice. METHODS: Forty congenitally obese mice were studied. Seven days prior to study, 20 mice received a single tail vein injection of adenovirus expressing recombinant murine adiponectin (APN; 2 × 108 plaque forming unit (pfu)), and the remainder received a control adenoviral vector expressing ß-galactosidase (ß-gal; 2 × 108 pfu). Half of the mice in each group had pancreatitis induced by cerulein injection (50 mcg/kg IP hourly for 6 h). The other half received saline on the same schedule. Serum APN concentration and pancreatic tissue concentrations of interleukin (IL)-6, IL-1ß, and MCP-1 were measured by ELISA. Histologic pancreatitis score was calculated based on the degree of inflammation (0-4), edema (0-4), and vacuolization (0-4). Data were analyzed by ANOVA and Tukey's tests; p < 0.05 was considered significant. RESULTS: No difference in body weight was observed between groups. Serum APN was significantly upregulated in the APN group compared with the ß-gal group. Pancreatic tissue concentration of IL-6 was significantly decreased in the APN group compared with the ß-gal group. No change either in pancreatic tissue concentration of IL-1ß and MCP-1 or in the severity of histologic pancreatitis were observed. CONCLUSION: Adiponectin upregulation modulates the pancreatic cytokine milieu but does not attenuate pancreatitis in this model of mild acute pancreatitis.

Validation of a novel, physiologic model of experimental acute pancreatitis in the mouse.

BACKGROUND: Many experimental models of acute pancreatitis suffer from lack of clinical relevance. We sought to validate a recently reported murine model of acute pancreatitis that more closely represents the physiology of human biliary pancreatitis. METHODS: Mice (C57BL/6J n=6 and CF-1 n=8) underwent infusion of 50µl of 5% sodium taurocholate (NaT) or 50µl of normal saline (NaCl) directly into the pancreatic duct. Twenty-four hours later, pancreatitis severity was graded histologically by three independent observers, and pancreatic tissue concentration of interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) were determined by ELISA. RESULTS: Twenty four hours after retrograde injection, the total pancreatitis score was significantly greater in mice infused with NaT than in those infused with NaCl (6.3 ± 1.2 vs. 1.2 ± 0.4, p<0.05). In addition, the inflammatory mediators IL-6 and MCP-1 were increased in the NaT group relative to the NaCl group. DISCUSSION: Retrograde pancreatic duct infusion of sodium taurocholate induces acute pancreatitis in the mouse. This model is likely representative of human biliary pancreatitis pathophysiology, and therefore provides a powerful tool with which to elucidate basic mechanisms underlying the pathogenesis of acute pancreatitis.

Periampullary choledochal diverticula are not choledochal cysts.

BACKGROUND: Choledochal cysts (CC) are rare, congenital anomalies of the biliary tree, associated with the development of biliary malignancies. Small periampullary choledochal diverticula (PCD) are a previously unreported type of biliary anomaly found primarily at ERCP. OBJECTIVE: The aim of this study was to assess whether PCD are congenital or acquired lesions by comparing the clinical presentation, management, and risk of malignancy between patients with PCD and CC. DESIGN: Retrospective analysis of a medical center database. SETTING: Academic tertiary referral center. PATIENTS: Over the study period, data regarding 16 patients with PCD were identified and compared with that of 118 patients with CC. INTERVENTION: Retrospective review of ERCP, surgical pathology, billings, and a diagnostic imaging database from our institution from 1985 to 2009 was done. MAIN OUTCOME MEASUREMENTS: Clinical presentation, investigations, management strategies, complication rates, and long-term outcomes were compared in patients with classic CC and PCD over the same time period. RESULTS: Patients with PCD were less likely to be female (50% vs 81%), older aged (mean 68 vs 28 years), to complain of abdominal pain (88% vs 68%), and were less likely to present with jaundice (0% vs 32%) (P<.05 for all pairs). Patients with PCD also were noted to have lower frequency of anomalous pancreatobiliary junction (0% vs 83%) and biliary neoplasia (0% vs 5%) and more likely to have sphincter of Oddi dysfunction (63% vs 1%). Management of PCD was done with ERCP in 87% of cases and with surgery in 0% of cases, whereas management of CC was done with ERCP in 20% of cases and surgery in 80% of cases (P<.001). Long-term complications at a mean follow-up of 3.7 years after therapy were more common in CC (40% vs 6%, P=.02). LIMITATIONS: Retrospective study. Lack of structured follow up. CONCLUSION: Small, periampullary, choledochal diverticula are a newly reported, likely acquired anomaly of the biliary tract that are frequently associated with sphincter of Oddi dysfunction and may be secondary to biliary hypertension. These acquired lesions should not be classified as CC.

Choledochoceles: are they choledochal cysts?

OBJECTIVE: The aim of this analysis was to report a multidisciplinary series comparing choledochoceles to Todani Types I, II, IV, and V choledochal cysts. SUMMARY BACKGROUND DATA: Choledochoceles have been classified as Todani Type III choledochal cysts. However, most surgical series of choledochal cysts have reported few choledochoceles because they are managed primarily by endoscopists. METHODS: Surgical, endoscopic, and radiologic records were reviewed at the Riley Children's Hospital and the Indiana University Hospitals to identify patients with choledochal cysts. Patient demographics, presenting symptoms, radiologic studies, associated abnormalities, surgical and endoscopic procedures as well as outcomes were reviewed. RESULTS: A total of 146 patients with "choledochal cysts" including 45 children (31%) and 28 with choledochoceles (18%) were identified, which represents the largest Western series. Patients with choledochoceles were older (50.7 vs. 29.0 years, P < 0.05) and more likely to be male (43% vs. 19%, P < 0.05), to present with pancreatitis (48% vs. 24%, P < 0.05) rather than jaundice (11% vs. 30%, P < 0.05) or cholangitis (0% vs. 21%, P < 0.05), to have pancreas divisum (38% vs. 10%, P < 0.01), and to be managed with endoscopic therapy (79% vs. 17%, P < 0.01). Two patients with choledochoceles (7%) had pancreatic neoplasms. CONCLUSIONS: Patients with choledochoceles differ from patients with choledochal cysts with respect to age, gender, presentation, pancreatic ductal anatomy, and their management. The association between choledochoceles and pancreas divisum is a new observation. Therefore, we conclude that classifications of choledochal cysts should not include choledochoceles.

Insulin, leptin, and tumoral adipocytes promote murine pancreatic cancer growth.

BACKGROUND: Obesity accelerates development and growth of human pancreatic cancer. We recently reported similar findings in a novel murine model of pancreatic cancer in congenitally obese mice. The current experiments were designed to evaluate the effects of diet-induced obesity on pancreatic cancer growth. METHODS: Thirty C57BL/6J female mice were fed either control 10% fat (n = 10) or 60% fat diet (n = 20) starting at age 6 weeks. At 11 weeks, 2.5 × 10(5) PAN02 murine pancreatic cancer cells were inoculated. After 6 weeks, tumors were harvested. Serum adiponectin, leptin, insulin, and glucose concentrations were measured. Tumor proliferation, apoptosis, adipocyte content, and tumor-infiltrating lymphocytes were evaluated. RESULTS: The diet-induced obesity diet led to significant weight gain (control 21.3 ± 0.6 g; diet-induced obesity 23.1 ± 0.5 g; p = 0.03). Mice heavier than 23.1 g were considered "Overweight." Tumors grew significantly larger in overweight (1.3 ± 0.3 g) compared to lean (0.5 ± 0.2 g; p = 0.03) mice; tumor size correlated positively with body weight (R = 0.56; p < 0.02). Serum leptin (3.1 ± 0.7 vs. 1.4 ± 0.2 ng/ml) and insulin (0.5 ± 0.2 vs. 0.18 ± 0.02 ng/ml) were significantly greater in overweight mice. Tumor proliferation, apoptosis, and tumor adipocyte volume were similar. T and B lymphocytes were observed infiltrating tumors from lean and overweight mice in similar number. CONCLUSION: These data show that diet-induced obesity accelerates the growth of murine pancreatic cancer.

Pancreatic surgery: evolution at a high-volume center.

BACKGROUND: Advances in imaging, minimally invasive techniques, and regionalization have changed pancreatic surgery. Therefore, the aims of this report are to determine whether the pancreatic operations or the spectrum of disease have evolved at a high-volume center. METHODS: From 1996 through 2009, 2,004 pancreatic operations were performed at Indiana University Hospital. The operations, pathology, and outcomes for 1996-2003 were compared with 2004-2009. RESULTS: In 2004-2009, more operations/year were performed (215 vs 89; P < .01) and patients were older (58.8 years vs 55.8 years; P < .01). In recent years, more pancreatoduodenectomies (55.0% vs 50.4%) and fewer pancreatojejunostomies (6.2% vs 12.6%) and Beger/Frey procedures (2.6% vs 4.8%) were performed (P < .05). In 2004-2009, pylorus preservation (81.1% vs 64.4%), laparoscopic distal pancreatectomy (33.9% vs 0%), and splenic preservation (25.3% vs 2.2%) were carried out more frequently (P < .001). Pathology review revealed more tumors (68.8% vs 60.4%) and less pancreatitis (29.2% vs 34.4%; P < .01). Thirty-day mortality improved from 2.5% to 1.8%. CONCLUSION: At a high-volume pancreatic surgery center, the number and age of the patients, the percentage of pancreatic resections, preservation of the pylorus and spleen as well as laparoscopic procedures, and the percentage of patients with tumors all have increased, whereas the outcomes continued to improve.