The PrEDICT-DGE score as a simple preoperative screening tool identifies patients at increased risk for delayed gastric emptying after pancreaticoduodenectomy.

BACKGROUND: Morbidity after Pancreaticoduodenectomy (PD) has remained unchanged over the past decade. Delayed Gastric Emptying (DGE) is a major contributor with significant impact on healthcare-costs, quality of life and, for malignancies, even survival. We sought to develop a scoring system to aid in easy preoperative identification of patients at risk for DGE. METHODS: The ACS-NSQIP dataset from 2014 to 2018 was queried for patients undergoing PD with Whipple or pylorus preserving reconstruction. 15,154 patients were analyzed using multivariable logistic regression to identify risk factors for DGE, which were incorporated into a prediction model. Subgroup analysis of patients without SSI or fistula (primary DGE) was performed. RESULTS: We identified 9 factors independently associated with DGE to compile the PrEDICT-DGE score: Procedures (Concurrent adhesiolysis, feeding jejunostomy, vascular reconstruction with vein graft), Elderly (Age>70), Ductal stent (Lack of biliary stent), Invagination (Pancreatic reconstruction technique), COPD, Tobacco use, Disease, systemic (ASA>2), Gender (Male) and Erythrocytes (preoperative RBC-transfusion). PrEDICT-DGE scoring strongly correlated with actual DGE rates (R2 = 0.95) and predicted patients at low, intermediate, and high risk. Subgroup analysis of patients with primary DGE, retained all predictive factors, except for age>70 (p = 0.07) and ASA(p = 0.30). CONCLUSION: PrEDICT-DGE scoring accurately identifies patients at high risk for DGE and can help guide perioperative management.

Impact of preoperative biliary drainage on 30 Day outcomes of patients undergoing pancreaticoduodenectomy for malignancy.

BACKGROUND: Preoperative biliary drainage (PBD) has been advocated to address the plethora of physiologic derangements associated with cholestasis. However, available literature reports mixed outcomes and is based on largely outdated and/or single-institution studies. METHODS: Patients undergoing PBD prior to pancreaticoduodenectomy (PD) for periampullary malignancy between 2014-2018 were identified in the ACS-NSQIP pancreatectomy dataset. Patients with PBD were propensity-score-matched to those without PBD and 30-day outcomes compared. RESULTS: 8,970 patients met our inclusion criteria. 4,473 with obstruction and PBD were matched to 829 with no preoperative drainage procedure. In the non-jaundiced cohort, 711 stented patients were matched to 2,957 without prior intervention. PBD did not influence 30-day mortality (2.2% versus 2.4%) or major morbidity (19.8% versus 20%) in patients with obstructive jaundice. Superficial surgical site infections (SSIs) were more common with PBD (6.8% versus 9.2%), however, no differences in deep or organ-space SSIs were found. Patients without obstruction prior to PBD exhibited a 3-fold increase in wound dehiscence (0.5% versus 1.5%) additionally to increased superficial SSIs. CONCLUSION: PBD was not associated with an increase in 30-day mortality or major morbidity but increased superficial SSIs. PBD should be limited to symptomatic, profoundly jaundiced patients or those with a delay prior to PD.

Construction and evolution of an Escherichia coli strain relying on nonoxidative glycolysis for sugar catabolism.

The Embden-Meyerhoff-Parnas (EMP) pathway, commonly known as glycolysis, represents the fundamental biochemical infrastructure for sugar catabolism in almost all organisms, as it provides key components for biosynthesis, energy metabolism, and global regulation. EMP-based metabolism synthesizes three-carbon (C3) metabolites before two-carbon (C2) metabolites and must emit one CO2 in the synthesis of the C2 building block, acetyl-CoA, a precursor for many industrially important products. Using rational design, genome editing, and evolution, here we replaced the native glycolytic pathways in Escherichia coli with the previously designed nonoxidative glycolysis (NOG), which bypasses initial C3 formation and directly generates stoichiometric amounts of C2 metabolites. The resulting strain, which contains 11 gene overexpressions, 10 gene deletions by design, and more than 50 genomic mutations (including 3 global regulators) through evolution, grows aerobically in glucose minimal medium but can ferment anaerobically to products with nearly complete carbon conservation. We confirmed that the strain metabolizes glucose through NOG by 13C tracer experiments. This redesigned E. coli strain represents a different approach for carbon catabolism and may serve as a useful platform for bioproduction.

CO2-fixing one-carbon metabolism in a cellulose-degrading bacterium Clostridium thermocellum.

Clostridium thermocellum can ferment cellulosic biomass to formate and other end products, including CO2 This organism lacks formate dehydrogenase (Fdh), which catalyzes the reduction of CO2 to formate. However, feeding the bacterium 13C-bicarbonate and cellobiose followed by NMR analysis showed the production of 13C-formate in C. thermocellum culture, indicating the presence of an uncharacterized pathway capable of converting CO2 to formate. Combining genomic and experimental data, we demonstrated that the conversion of CO2 to formate serves as a CO2 entry point into the reductive one-carbon (C1) metabolism, and internalizes CO2 via two biochemical reactions: the reversed pyruvate:ferredoxin oxidoreductase (rPFOR), which incorporates CO2 using acetyl-CoA as a substrate and generates pyruvate, and pyruvate-formate lyase (PFL) converting pyruvate to formate and acetyl-CoA. We analyzed the labeling patterns of proteinogenic amino acids in individual deletions of all five putative PFOR mutants and in a PFL deletion mutant. We identified two enzymes acting as rPFOR, confirmed the dual activities of rPFOR and PFL crucial for CO2 uptake, and provided physical evidence of a distinct in vivo "rPFOR-PFL shunt" to reduce CO2 to formate while circumventing the lack of Fdh. Such a pathway precedes CO2 fixation via the reductive C1 metabolic pathway in C. thermocellum These findings demonstrated the metabolic versatility of C. thermocellum, which is thought of as primarily a cellulosic heterotroph but is shown here to be endowed with the ability to fix CO2 as well.

The effect of resident involvement on bariatric surgical outcomes: an ACS-NSQIP analysis.

BACKGROUND: Surgical residency training programs in the United States are modeled on the principle of graduated responsibility. Residents are given greater responsibility and autonomy in the operating room and during perioperative care as they gain surgical skills and progress through their training. The impact of this method of surgical training on patient outcomes remains unknown. The purpose of this study is to compare early patient morbidity and mortality after bariatric surgery in cases with and without resident participation using the American College of Surgeons National Surgical Quality Improvement Program database. METHODS: All patients undergoing bariatric surgery from 2006 through 2010 were identified within the American College of Surgeons National Surgical Quality Improvement Program database. These patients were divided into three groups based on resident involvement in their surgery (no resident, senior-level resident, and junior-level resident). The effect of resident involvement and postgraduate year level on 30-d morbidity and mortality was investigated using composite outcomes, including cardiac events (acute myocardial infarction or cardiac arrest requiring cardiopulmonary resuscitation), pulmonary events (pneumonia, prolonged intubation, or unplanned reintubation), wound (superficial surgical site infection, deep surgical site infection, organ-space infection, or dehiscence), septic events (sepsis and septic shock), clotting events (pulmonary embolism and deep venous thrombosis), and renal events (urinary tract infection and acute kidney injury requiring dialysis). Length of hospital stay, unplanned return to the operating room, and 30-d mortality were also investigated. RESULTS: A total of 19,616 patients underwent bariatric surgery from the year 2006 through 2010; 8960 (45.7%) procedures were performed with resident involvement, with 5406 (36.7%) of these cases involving a senior-level resident. Operations involving a senior-level resident were more likely to experience postoperative cardiac events (P < 0.006), pulmonary events (P = 0.03), wound events (P = 0.01), septic events (P < 0.002), renal events (P ≤ 0.01), prolonged operative time (P < 0.0001), and a prolonged length of hospital stay (P < 0.0001) than those that involved either no resident or a junior-level resident. CONCLUSIONS: Although bariatric operations involving senior-level residents have more statistically significant morbidity outcomes, these morbidity outcomes are related more to perioperative care rather than intraoperative resident involvement. This suggests that more emphasis on perioperative progressive responsibility may be needed to match operative oversight.

Laparoscopic versus open ventral hernia repair in patients with chronic liver disease.

BACKGROUND: Previous studies demonstrated laparoscopic ventral hernia repair (LVHR) to be associated with fewer short-term complications than open ventral hernia repair (OVHR). Little literature is available comparing LVHR and OVHR in chronic liver disease (CLD) patients. METHODS: Patients with model for end-stage liver disease score ≥9 who underwent elective ventral hernia repair in the National Surgical Quality Improvement Program Database were included. 30-day outcomes were compared between LVHR and OVHR after adjusting for hernia disease severity, baseline comorbidities and demographic factors. RESULTS: A total of 3594 ventral hernia repairs were included, 536 (14.9 %) of which were LVHR. After adjusting for other confounders, LVHR was associated with a lower incidence of wound-related complications (0.23, 95 % CI 0.07-0.74, p = 0.01), shorter length of stay (mean 3.7 vs. 5.0 days, p < 0.01) than OVHR, but similar systemic complications (p = 0.77), bleeding complications (p = 0.69), unplanned reoperation (p = 0.74) or readmission (p = 0.40). Propensity score-matched comparison showed similar conclusions. Five hundred and sixty-two patients had ascites, among whom 35 (6.2 %) underwent LVHR. In this subcohort, LVHR was associated with higher mortality (OR 5.36, 95 % CI 1.00-28.60, p = 0.05), systemic complications (OR 7.03, 95 % CI 2.06-24.00, p < 0.01), and unplanned reoperation (OR 6.03, 95 % CI 1.51-24.12, p = 0.01) than OVHR. CONCLUSIONS: In comparison with OVHR, LVHR is associated with similar short-term outcomes except for lower wound-related complications and shorter length of stay in CLD patients. However, when patients have ascites, LVHR is associated with higher mortality, systemic complications, and unplanned reoperation.

Consolidated bioprocessing of cellulose to isobutanol using Clostridium thermocellum.

Consolidated bioprocessing (CBP) has the potential to reduce biofuel or biochemical production costs by processing cellulose hydrolysis and fermentation simultaneously without the addition of pre-manufactured cellulases. In particular, Clostridium thermocellum is a promising thermophilic CBP host because of its high cellulose decomposition rate. Here we report the engineering of C. thermocellum to produce isobutanol. Metabolic engineering for isobutanol production in C. thermocellum is hampered by enzyme toxicity during cloning, time-consuming pathway engineering procedures, and slow turnaround in production tests. In this work, we first cloned essential isobutanol pathway genes under different promoters to create various plasmid constructs in Escherichia coli. Then, these constructs were transformed and tested in C. thermocellum. Among these engineered strains, the best isobutanol producer was selected and the production conditions were optimized. We confirmed the expression of the overexpressed genes by their mRNA quantities. We also determined that both the native ketoisovalerate oxidoreductase (KOR) and the heterologous ketoisovalerate decarboxylase (KIVD) expressed were responsible for isobutanol production. We further found that the plasmid was integrated into the chromosome by single crossover. The resulting strain was stable without antibiotic selection pressure. This strain produced 5.4 g/L of isobutanol from cellulose in minimal medium at 50(o)C within 75 h, corresponding to 41% of theoretical yield.

Isobutanol production at elevated temperatures in thermophilic Geobacillus thermoglucosidasius.

The potential advantages of biological production of chemicals or fuels from biomass at high temperatures include reduced enzyme loading for cellulose degradation, decreased chance of contamination, and lower product separation cost. In general, high temperature production of compounds that are not native to the thermophilic hosts is limited by enzyme stability and the lack of suitable expression systems. Further complications can arise when the pathway includes a volatile intermediate. Here we report the engineering of Geobacillus thermoglucosidasius to produce isobutanol at 50°C. We prospected various enzymes in the isobutanol synthesis pathway and characterized their thermostabilities. We also constructed an expression system based on the lactate dehydrogenase promoter from Geobacillus thermodenitrificans. With the best enzyme combination and the expression system, 3.3g/l of isobutanol was produced from glucose and 0.6g/l of isobutanol from cellobiose in G. thermoglucosidasius within 48h at 50°C. This is the first demonstration of isobutanol production in recombinant bacteria at an elevated temperature.

Attending Specialization and 30-Day Outcomes Following Laparoscopic Bariatric Surgery: an Analysis of the ACS-MBSAQIP Database.

BACKGROUND: Surgeon and hospital volume are factors that have been shown to impact outcomes following bariatric surgery. Nevertheless, there is a paucity of literature investigating surgeon training on bariatric surgery outcomes. The purpose of our study was to determine if bariatric specialty training leads to improved short-term outcomes following laparoscopic bariatric surgery using the American College of Surgeons Metabolic and Bariatric Surgery Accreditation Quality Improvement Program (ACS-MBSAQIP) database. METHODS: All patients undergoing first-time, elective, laparoscopic bariatric surgery from 2015 to 2016 were identified within the ACS-MBSAQIP database. Patients were divided into two groups based on the type of bariatric procedure performed and the surgeon performing the procedure. Thirty-day outcomes were compared between the groups using multivariable logistic regression analysis. RESULTS: A total of 140,340 patients met inclusion criteria. Higher risk patients with more associated comorbidities underwent bariatric surgery by a metabolic and bariatric surgeon. After controlling for these differences, patients who underwent Roux-en-Y gastric bypass (RYGB) had similar 30-day irrespective of the surgeon performing the procedure while patients who underwent sleeve gastrectomy (SG) by a metabolic and bariatric surgeon (MBS) had improved 30-day outcomes. CONCLUSION: Surgeon type is associated with 30-day morbidity and mortality outcomes for SG but not for RYGB. These differences in 30-day morbidity and mortality outcomes may be facilitated by institutional factors, surgeon experience, and participation in bariatric surgery accredited centers. Standardization of the perioperative process for both surgeons and institutions may improve 30-day morbidity and mortality outcomes for all patients who undergo laparoscopic bariatric surgery.

National trends in total vs subtotal gastrectomy for middle and distal third gastric cancer.

BACKGROUND: To identify trends in total and subtotal gastrectomy for middle and distal third gastric adenocarcinoma in the U.S. METHODS: NCDB was queried for patients with stage 0-III middle or distal gastric adenocarcinoma treated with total or subtotal gastrectomy. Statistical analysis including cox proportional hazards model was performed to examine overall survival by stage. RESULTS: 1,628 (85%) underwent subtotal gastrectomy and 283 (15%) underwent total. 1113 patients (58%) had distal tumors and 798 (42%) had middle tumors. Total gastrectomy patients more often had poor tumor grade (60% vs 50%,p < 0.01), larger size (46.3 mm vs 37.8 mm,p < 0.0001), had positive nodes (3.6 ± 5.9 vs 2.2 ± 4.1,p < 0.0001), underwent chemoradiation (13% vs 6%,p < 0.0001), and were higher clinical stage (p < 0.05). An overall survival curve showed an adjusted HR of 2.7 for total vs subtotal gastrectomy at clinical stage 3 (p < 0.05). CONCLUSIONS: Total gastrectomy is performed for larger, more aggressive tumors with higher stage. Subtotal gastrectomy may have a survival benefit for stage III gastric cancers.

The effect of bougie size and distance from the pylorus on dehydration after laparoscopic sleeve gastrectomy: an analysis of the ACS-MBSAQIP database.

BACKGROUND: Dehydration is the most common cause of readmission after laparoscopic sleeve gastrectomy (SG). Bougie size and distance from the pylorus, both of which have been associated with rates of dehydration postoperatively, varies by surgeon and across institutions. OBJECTIVES: To determine if there is an association between bougie size or distance from the pylorus on the rate of dehydration after laparoscopic SG. SETTING: American College of Surgeons Metabolic and Bariatric Surgery Accreditation Quality Improvement Program database. METHODS: All patients undergoing first-time, elective laparoscopic SG from 2015-2016 were identified. The association of bougie size and distance from the pylorus on the rate of dehydration within the first 30 days postoperatively was investigated. RESULTS: The inclusion criteria were met by 170,751 patients. The most commonly used bougie size was 36 Fr and the most common distance from the pylorus at which the gastric sleeve was started was 5 cm. Patients were divided into 4 groups based on bougie size and distance from the pylorus (Group 1: bougie size <36 Fr, pylorus distance <4 cm; Group 2: bougie size ≥36 Fr, pylorus distance <4 cm; Group 3: bougie size ≥36 Fr, pylorus distance ≥4 cm; and Group 4: bougie size <36 Fr, pylorus distance ≥4 cm). Patients in Group 4 were significantly less likely than any other group to experience dehydration-related complications. CONCLUSION: Both distance from the pylorus and bougie size are significantly associated with dehydration-related complications after SG. Consideration should be made for standardizing these technical aspects of SG to help reduce the rate of postoperative dehydration and hospital readmission.

The Effect of Pancreaticojejunostomy Technique on Fistula Formation Following Pancreaticoduodenectomy in the Soft Pancreas.

INTRODUCTION: A soft pancreas has been associated with an increased risk of post-operative pancreatic fistula formation. Few studies have evaluated the effect of anastomotic technique (duct to mucosa vs invagination) on fistula formation. This study aims to compare the effect of anastomotic technique on fistula formation among patients with a soft pancreas in a large multiinstitutional database. METHODS: The targeted pancreas module of the American College of Surgeons-National Surgical Quality Improvement Program (NSQIP) Database was used. All patients with a soft pancreas who underwent pancreaticoduodenectomy from 2014 to 2015 were identified. Demographic data, comorbid conditions, operative variables, and 30-day outcomes were compared using univariate and multivariable analyses. RESULTS: A total of 975 patients met inclusion criteria. Eight-hundred fifty four (88%) underwent a duct to mucosa pancreaticojejunostomy technique and 121 (12%) underwent invagination. Patients who underwent invagination had higher 30-day mortality (5.8% vs 1.4%, p < 0.01), higher fistula formation (38% vs 25%, p < 0.01), and more often had percutaneous drain placement post-operatively (27% vs 14%, p < 0.01). Following multivariable analysis, invagination remained associated with pancreatic fistula formation (OR 2.5, CI 1.4-4.3) and post-operative percutaneous drain placement (OR 1.8, CI 1.1-2.9). CONCLUSION: Invagination technique for pancreaticojejunostomy in patients with a soft pancreas is associated with increased rates of pancreatic fistula. Surgeons should consider utilizing a duct to mucosa technique when feasible to decrease morbidity following pancreaticoduodenectomy in this patient population.

Barriers to bariatric surgery: Factors influencing progression to bariatric surgery in a U.S. metropolitan area.

BACKGROUND: Bariatric surgery is an effective and durable treatment for obesity. However, the number of patients that progress to bariatric surgery after initial evaluation remains low. OBJECTIVES: The purpose of this study was to identify factors influencing a qualified patient's successful progression to surgery in a U.S. metropolitan area. SETTING: Academic, university hospital. METHODS: A single-institution retrospective chart review was performed from 2003 to 2016. Patient demographics and follow-up data were compared between those who did and did not progress to surgery. A follow-up telephone survey was performed for patients who failed to progress. Univariate analyses were performed and statistically significant variables of interest were analyzed using a multivariable logistic regression model. RESULTS: A total of 1102 patients were identified as eligible bariatric surgery candidates. Four hundred ninety-eight (45%) patients progressed to surgery and 604 (55%) did not. Multivariable analysis showed that patients who did not progress were more likely male (odds ratio [OR] 2.2 confidence interval [CI]: 1.2-4.2, P < .05), smokers (OR 2.4 CI: 1.1-5.4, P < .05), attended more nutrition appointments (OR 2.1 CI: 1.5-2.8, P < .0001), attended less total preoperative appointments (OR .41 CI: .31-.55, P < .0001), and resided in-state compared with out of state (OR .39 CI: .22-.68, P < .05). The top 3 patient self-reported factors influencing nonprogression were fear of complication, financial hardship, and insurance coverage. CONCLUSIONS: Multiple patient factors and the self-reported factors of fear of complication and financial hardship influenced progression to bariatric surgery in a U.S. metropolitan population. Bariatric surgeons and centers should consider and address these factors when assessing patients.

The association of IVC filter placement with the incidence of postoperative pulmonary embolism following laparoscopic bariatric surgery: an analysis of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Project.

BACKGROUND: Venous thromboembolism, including pulmonary embolism (PE) and deep venous thrombosis, is a leading cause of morbidity and mortality after bariatric surgery. Inferior vena cava filters (IVCFs) have been used as a method to reduce the incidence of clinically significant PEs after bariatric surgery. OBJECTIVES: To compare the incidence of postoperative PEs in patients with IVCFs with those in patients without IVCFs at the time of bariatric surgery. SETTING: American College of Surgeons Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program. METHODS: All patients undergoing laparoscopic Roux-en-Y gastric bypass or sleeve gastrectomy from 2015 to 2016 were identified within the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program database. Patients with an IVCF present at the time of surgery were compared with those patients without an IVCF present at the time of surgery with respect to preoperative patient variables, operative variables, incidence of 30-day PE, deep venous thrombosis, and additional 30-day morbidity and mortality. RESULTS: A total of 286,704 patients met the inclusion criteria; 2512 (.9%) patients had an IVCF present at the time of surgical intervention, of which 1747 (69.5%) were placed within 30 days of bariatric surgery. Patients with an IVCF were higher-risk patients as determined by previously established risk factors for venous thromboembolism events. When a subgroup matched analysis using variables associated with the risk of venous thromboembolism events was performed looking at higher-risk patients only, there was no statistically significant difference in the incidence of PE based on the presence of an IVCF. CONCLUSION: IVCFs are being selectively placed in higher-risk patients. Despite their selective use, IVCFs do not appear to have a protective benefit with respect to the incidence of postoperative PE events.

Older Age Confers a Higher Risk of 30-Day Morbidity and Mortality Following Laparoscopic Bariatric Surgery: an Analysis of the Metabolic and Bariatric Surgery Quality Improvement Program.

INTRODUCTION: There is a paucity of literature describing the association of age with the risk of adverse events following bariatric surgery. The purpose of this study is to investigate the association of age with 30-day morbidity and mortality following laparoscopic bariatric surgery using the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) database. METHODS: All adult patients undergoing laparoscopic Roux-en-Y gastric bypass (RNGYB) or sleeve gastrectomy (SG) were identified within the MBSAQIP database. Patients were divided into five equal age quintiles. Binary outcomes of interest, including cardiac, pulmonary, wound, septic, clotting, and renal events, in addition to the incidence of related 30-day unplanned reintervention, related 30-day mortality, and a composite morbidity and mortality outcome were compared across the age quintiles and procedures. RESULTS: A total of 266,544 patients met inclusion criteria. Older age was associated with an increased risk of all morbidity outcomes except venous thromboembolism events, 30-day mortality, and the composite morbidity and mortality outcome. Patients who underwent Roux-en-Y gastric bypass had worse outcomes per quintile for almost every outcome of interest when compared to patients who underwent sleeve gastrectomy. CONCLUSION: Older patients and patients who undergo Roux-en-Y gastric bypass are at an increased risk of perioperative morbidity and mortality following laparoscopic bariatric surgery. Additional studies are needed to determine the association of age with long-term weight loss and cardiometabolic comorbidity resolution following bariatric surgery in order to determine if the increased perioperative risk is offset by improved long-term outcomes in older patients undergoing bariatric surgery.

Neoadjuvant Radiation Is Associated with Fistula Formation Following Pancreaticoduodenectomy.

BACKGROUND: Post-operative pancreatic fistulas remain a significant source of morbidity following pancreatic surgery. Few studies have evaluated the effect of neoadjuvant chemotherapy and radiation on this adverse outcome. This study aims to evaluate the effects of neoadjuvant therapy on 30-day morbidity and mortality following pancreaticoduodenectomy. STUDY DESIGN: A retrospective analysis was performed utilizing the targeted pancreas module of the National Surgical Quality Improvement Project (NSQIP) from 2014 to 2015 for patients undergoing pancreaticoduodenectomy with pancreaticojejunal reconstruction. A fistula was defined according to the NSQIP definition. Patient demographics, operative variables, and 30-day outcomes were compared between those who received no neoadjuvant therapy, chemoradiation, chemotherapy alone, and radiation alone. Univariate analysis was completed using chi-square, Fisher exact test, Student's t test, and Mann-Whitney U test where appropriate. Independent predictors of fistula formation were established using multivariable regression. A P value < 0.05 was considered significant. RESULTS: Three thousand one hundred fourteen patients were included of which 559 patients (18%) developed a pancreatic fistula. Two thousand six hundred thirty-five (85%) patients did not undergo neoadjuvant therapy, 207 (6.6%) had chemoradiation, 256 (8.2%) had chemotherapy alone, and 16 (0.5%) had radiation alone. Patients who developed a fistula had increased 30-day mortality (4.9 vs. 1.7%, P < .001) and major morbidities. Following multivariable analysis, neoadjuvant radiation (OR 2.1, 95% CI 1.0-4.5) was associated with increased fistula formation while neoadjuvant chemotherapy (OR 0.5, 95% CI 0.3-0.9) was protective. CONCLUSION: Neoadjuvant chemotherapy provides protection against the development of pancreatic fistulas while neoadjuvant radiation potentiates formation likely due to their effects on the texture of the pancreatic gland. Given the morbidity of pancreatic fistula formation, these factors should be considered in neoadjuvant regimens.

Expressing the Thermoanaerobacterium saccharolyticum pforA in engineered Clostridium thermocellum improves ethanol production.

BACKGROUND: Clostridium thermocellum has been the subject of multiple metabolic engineering strategies to improve its ability to ferment cellulose to ethanol, with varying degrees of success. For ethanol production in C. thermocellum, the conversion of pyruvate to acetyl-CoA is catalyzed primarily by the pyruvate ferredoxin oxidoreductase (PFOR) pathway. Thermoanaerobacterium saccharolyticum, which was previously engineered to produce ethanol of high yield (> 80%) and titer (70 g/L), also uses a pyruvate ferredoxin oxidoreductase, pforA, for ethanol production. RESULTS: Here, we introduced the T. saccharolyticum pforA and ferredoxin into C. thermocellum. The introduction of pforA resulted in significant improvements to ethanol yield and titer in C. thermocellum grown on 50 g/L of cellobiose, but only when four other T. saccharolyticum genes (adhA, nfnA, nfnB, and adhEG544D ) were also present. T. saccharolyticum ferredoxin did not have any observable impact on ethanol production. The improvement to ethanol production was sustained even when all annotated native C. thermocellum pfor genes were deleted. On high cellulose concentrations, the maximum ethanol titer achieved by this engineered C. thermocellum strain from 100 g/L Avicel was 25 g/L, compared to 22 g/L for the reference strain, LL1319 (adhA(Tsc)-nfnAB(Tsc)-adhEG544D (Tsc)) under similar conditions. In addition, we also observed that deletion of the C. thermocellum pfor4 results in a significant decrease in isobutanol production. CONCLUSIONS: Here, we demonstrate that the pforA gene can improve ethanol production in C. thermocellum as part of the T. saccharolyticum pyruvate-to-ethanol pathway. In our previous strain, high-yield (~ 75% of theoretical) ethanol production could be achieved with at most 20 g/L substrate. In this strain, high-yield ethanol production can be achieved up to 50 g/L substrate. Furthermore, the introduction of pforA increased the maximum titer by 14%.

Open Colectomies of Shorter Operative Time Do Not Result in Improved Outcomes Compared With Prolonged Laparoscopic Operations.

BACKGROUND: Laparoscopic colectomies are associated with reduced perioperative morbidity and mortality compared with open surgery. Nevertheless, many surgeons continue to utilize an open surgical approach due to the perceived benefits of shorter operative times. This study aims to compare the outcomes of laparoscopic versus open colectomies of equal or shorter operative duration. METHODS: All patients undergoing elective laparoscopic or open colectomy in the American College of Surgeons National Surgical Quality Improvement Project (ACS-NSQIP) were identified from the years 2005 through 2012. Patients were stratified first by operative procedure including partial colectomy, total colectomy, or low anterior resection. Each surgical group was then divided into 4 groups according to operative time: <90 minutes, ≥90 minutes and <3 hours, ≥3 hours and <6 hours, and ≥6 hours. In total, 30-day outcomes were compared between laparoscopic operations and open procedures of shorter or equivalent durations within each surgical group. Multivariate logistic regression was utilized to account for differences in patient demographics and comorbidities between the surgical groups. RESULTS: In total, 156,503 patients met inclusion criteria; 112,053 (71.6%) patients underwent a partial colectomy, 13,838 (8.8%) patients underwent a total colectomy, and 30,612 (19.6%) patients underwent a low anterior resection. A laparoscopic approach was used in 34% (37,789 patients) of the partial colectomies performed, 31% (4285 patients) of the total colectomies performed, and 45% (13,850 patients) of the low anterior resections performed. For all procedures, laparoscopic operations <6 hours were associated with superior outcomes compared with shorter open procedures. The benefit of laparoscopic operations was lost when operative time exceeded 6 hours. CONCLUSIONS: Laparoscopic colectomies are associated with improved outcomes compared with open operations that do not exceed an operative time of 6 hours. Given the potential to improve patient outcomes, consideration should be given to the laparoscopic approach for all colon surgeries expected to be completed in <6 hours.

Engineering a Thermostable Keto Acid Decarboxylase Using Directed Evolution and Computationally Directed Protein Design.

Keto acid decarboxylase (Kdc) is a key enzyme in producing keto acid derived higher alcohols, like isobutanol. The most active Kdc's are found in mesophiles; the only reported Kdc activity in thermophiles is 2 orders of magnitude less active. Therefore, the thermostability of mesophilic Kdc limits isobutanol production temperature. Here, we report development of a thermostable 2-ketoisovalerate decarboxylase (Kivd) with 10.5-fold increased residual activity after 1h preincubation at 60 °C. Starting with mesophilic Lactococcus lactis Kivd, a library was generated using random mutagenesis and approximately 8,000 independent variants were screened. The top single-mutation variants were recombined. To further improve thermostability, 16 designs built using Rosetta Comparative Modeling were screened and the most active was recombined to form our best variant, LLM4. Compared to wild-type Kivd, a 13 °C increase in melting temperature and over 4-fold increase in half-life at 60 °C were observed. LLM4 will be useful for keto acid derived alcohol production in lignocellulosic thermophiles.

Open, intraperitoneal, ventral hernia repair: lessons learned from laparoscopy.

Recent literature suggests that laparoscopic repair of ventral hernias may have very low recurrence rates. However, laparoscopy may not be feasible in certain situations. We describe an open technique that uses the tension-free retrofascial principles of laparoscopic repair without the need for subcutaneous flaps. Through an incision in the hernia, the peritoneum is entered and adhesions are taken down. A piece of DualMesh (W.L. Gore & Associates, Inc, Newark, Del) is trimmed to fit with a 5-cm circumferential overlap. A vertical incision is made in the mid portion of the mesh. The mesh is fixed in an intraperitoneal retrofascial position using GORE-TEX sutures (W.L. Gore & Associates, Inc). The sutures are brought through the abdominal wall using a laparoscopic suture passer and tied into place on one side of the mesh. That side is then tacked to the posterior fascia with a spiral tacking device. The other side is sutured into place in a similar fashion and then tacked to the fascia by passing the spiral tacking device through the incision in the mesh. The mesh incision is closed with a running GORE-TEX suture. The overlying tissues are closed in layers.