Lack of functionally active sweet taste receptors in the jejunum in vivo in the rat.

BACKGROUND: When studied in enterocyte-like cell lines (Caco-2 and RIE cells), agonists and antagonists of the sweet taste receptor (STR) augment and decrease glucose uptake, respectively. We hypothesize that exposure to STR agonists and antagonists in vivo will augment glucose absorption in the rat. MATERIALS AND METHODS: About 30-cm segments of jejunum in anesthetized rats were perfused with iso-osmolar solutions containing 10, 35, and 100 mM glucose solutions (n = 6 rats, each group) with and without the STR agonist 2 mM acesulfame potassium and the STR inhibitor 10 µM U-73122 (inhibitor of the phospholipase C pathway). Carrier-mediated absorption of glucose was calculated by using stereospecific and nonstereospecific (14)C-d-glucose and (3)H-l-glucose, respectively. RESULTS: Addition of the STR agonist acesulfame potassium to the 10, 35, and 100 mM glucose solutions had no substantive effects on glucose absorption from 2.1 ± 0.2 to 2.0 ± 0.3, 5.8 ± 0.2 to 4.8 ± 0.2, and 15.5 ± 2.3 to 15.7 ± 2.7 µmoL/min/30-cm intestinal segment (P > 0.05), respectively. Addition of the STR inhibitor (U-73122) also had no effect on absorption in the 10, 35, and 100 mM solutions from 2.3 ± 0.1 to 2.1 ± 0.2, 7.7 ± 0.5 to 7.2 ± 0.5, and 15.7 ± 0.9 to 15.2 ± 1.1 µmoL/min/30-cm intestinal segment, respectively. CONCLUSIONS: Provision of glucose directly into rat jejunum does not augment glucose absorption via STR-mediated mechanisms within the jejunum in the rat. Our experiments show either no major role of STRs in mediating postprandial augmentation of glucose absorption or that proximal gastrointestinal tract stimulation of STR or other luminal factors may be required for absorption of glucose to be augmented by STR.

A rare complication of secondary pneumothorax following exploratory laparotomy for a small bowel obstruction: Case report.

INTRODUCTION: Small bowel obstruction (SBO) is recognized as the most common surgical emergency following abdominal procedures. Moreover, a pneumothorax secondary to an SBO is an infrequent phenomenon less commonly reported in recent literature. Clinical presentation includes progressive dyspnea and fatigue. The diagnosis was made with imaging. In this case report, the authors present a rare case of concurrent surgical complications (pneumothorax, SBO, perforation of the stomach, and hiatal hernia). CASE PRESENTATION: A 62 years-old African American patient who presented with severe sudden onset difficulty breathing two days following laparoscopic toupet fundoplication procedure. She was given oxygen via cannula and the underwent chest tube insertion. She was then transferred to different facility under care of a cardio thoracic surgeon. CLINICAL DISCUSSION: Although SBO is most common emergency following an abdominal procedure, pneumothorax is rarely reported. This case report depicts a unique presentation of pneumothorax secondary to SBO and a discussion section conferring complication risk versus benefits of diverse management modalities (surgical or conservative), and a review of recent literature, further aiding healthcare professionals in the diagnosis and management of patients with SBO complications. CONCLUSION: Review of this case and the literature show a rare presentation of secondary pneumothorax following exploratory laparotomy for SBO. Recognizing the clinical signs and even a small suspicion should prompt one to order imaging. Chest X-ray is inexpensive and can rapidly rule out pneumothorax. These complications have high mortality in patients above the age of 60 years, hence, timely management is of utmost importance.

Differentiating passive from transporter-mediated uptake by PepT1: a comparison and evaluation of four methods.

BACKGROUND: To quantify transmembrane transport of dipeptides by PepT1, passive uptake (non-PepT1 mediated) must be subtracted from total (measured) uptake. Three methods have been described to estimate passive uptake: perform experiments at cold temperatures, inhibit target dipeptide uptake with a greater concentration of a second dipeptide, or use modified Michaelis-Menten kinetics. We hypothesized that performing uptake experiments at pH 8.0 would estimate passive uptake accurately, because PepT1 requires a proton gradient. Our aim was to determine the most accurate method to estimate passive uptake. METHODS: Caco-2 cells were incubated with various concentrations of glycyl-sarcosine (gly-sar) at pH 6.0 and at 37°C to measure total uptake. Passive uptake was estimated: (1) by incubating Caco-2 cells with varying concentrations of gly-sar at 4°C, (2) in the presence of 50 mM glycyl-leucine, (3) in solution at pH 8.0, or (4) using modified Michaelis-Menten kinetics. PepT1-mediated uptake was calculated by subtracting passive uptake from total uptake. K(m), V(max), and % gly-sar transported by PepT1 were calculated and compared. RESULTS: K(m), V(max), and % gly-sar transported by PepT1 varied from 0.7 to 2.4 mM, 8.4 to 21.0 nmol/mg protein/10 min, and 69% to 87%, respectively. Uptakes calculated with cold, 50 mM gly-leu and using modified Michaelis-Menten kinetics were similar but differed significantly from uptake at pH 8.0 (P < 0.001). CONCLUSIONS: Estimating passive uptake at pH 8.0 does not appear to be accurate. Measuring uptake at cold temperatures or in the presence of a greater concentration of a second dipeptide, and confirming results with modified Michaelis-Menten kinetics is recommended.

Revisional bariatric surgery can improve refractory metabolic disease.

BACKGROUND: It remains unclear if patients undergoing revisional surgery for inadequate weight loss/recidivism can achieve improvement of refractory metabolic syndrome (MetS). OBJECTIVE: We aimed to evaluate metabolic outcomes after reoperative bariatric surgery for unsatisfactory weight loss in patients with refractory MetS. SETTING: Academic Hospital. METHODS: We retrospectively reviewed all revisional bariatric surgery cases performed for inadequate weight loss/recidivism at our center and analyzed all cases in which the patient had ongoing uncontrolled diabetes or MetS. RESULTS: In total, 121 reoperative bariatric cases for inadequate weight loss/recidivism were identified. Of those, 31.4% (N = 38) had MetS and 33.9% (N = 41) were diabetic at the time of primary bariatric surgery. At revisional surgery, 15 (39.5%) patients still met criteria for MetS and 7 (17.1%) had hemoglobin A1c (HbA1c)≥6.0%. Of those with refractory MetS (N = 15) at revisional surgery, a mean percent excess weight loss (%EWL) of 59.4±21.2% at mean 40.1±29.9 months follow-up corresponded to a mean decrease in triglyceride of 65.2 mg/dL, mean increase in high-density lipoprotein cholesterol (HDL) of 12.1 mg/dL, and mean decrease in plasma glucose of 58.8 mg/dL. Mean percent total weight loss was 27.3%. One patient still met criteria for MetS. Of those with HbA1c≥6.0% at reoperative surgery (N = 7), a mean %EWL of 63.0±22.9% at mean 51.6±36.6 months follow-up corresponded to a mean decrease in HbA1c of 1.6%. Three patients still had HbA1c≥6.0%, but only 1 had HbA1c≥ 6.5%. CONCLUSION: Although further research is needed, this report suggests that revisional bariatric surgery is capable of treating both inadequate weight loss and refractory metabolic disease.

A Challenge between Trainee Education and Patient Safety: Does Fellow Participation Impact Postoperative Outcomes Following Bariatric Surgery?

BACKGROUND: Surgical training may potentially influence patient care. A safe, high-quality bariatric and metabolic surgery practice requires dedicated and specialized training commonly acquired during a fellowship. This study evaluates the impact of fellow participation on early postoperative outcomes in bariatric surgery. METHODS: From the American College of Surgeons (ACS-NSQIP) database, we identified all obese patients who had undergone primary laparoscopic Roux-en-Y gastric bypass (LRYGB) and sleeve gastrectomy (LSG) between 2010 and 2012. Logistic regression was used to prognosticate the surgical fellow (PGY-6, 7, or 8) participation in bariatric surgeries on perioperative outcomes, as compared to surgeries with no trainee participation. RESULTS: The study cohort consisted of 10,838 patients (8819 LRYGB, 2019 LSG, 32 % fellow participation). Fellows participated in higher-risk surgeries. Fellow involvement was associated with increased operative time in LRYGB (difference 42.4 ± 1.2 min, p < 0.001) and in LSG (difference 38.8 ± 2.5 min, p < 0.001). Multivariate regression revealed that fellow involvement in LSG did not significantly alter postoperative adverse events. Conversely, in the LRYGB group, fellow participation was independently associated with higher rates of overall complications (OR = 1.37, 95 % CI 1.16-1.63), serious complications (OR = 1.23, 95 % CI 1.00-1.52), surgical complications (OR = 1.42; 95 % CI 1.17-1.73), and reoperation (OR = 1.43, 95 % CI 1.10-1.87). On adjusted analysis, while readmission was higher with fellow involvement in both procedures, mortality rates were comparable. CONCLUSIONS: Fellow involvement resulted in a clinically appreciable increase in operative times. Fellow participation in the operating room was also independently associated with worse early postoperative outcomes following LRYGB, but was not the case for LSG. Promoting proficiency in surgical simulation laboratories and a gradual participation of fellows from LSG to LRYGB during fellowship may be associated with a reduction in postoperative complications.

Categorizing dynamic textures using a bag of dynamical systems.

We consider the problem of categorizing video sequences of dynamic textures, i.e., nonrigid dynamical objects such as fire, water, steam, flags, etc. This problem is extremely challenging because the shape and appearance of a dynamic texture continuously change as a function of time. State-of-the-art dynamic texture categorization methods have been successful at classifying videos taken from the same viewpoint and scale by using a Linear Dynamical System (LDS) to model each video, and using distances or kernels in the space of LDSs to classify the videos. However, these methods perform poorly when the video sequences are taken under a different viewpoint or scale. In this paper, we propose a novel dynamic texture categorization framework that can handle such changes. We model each video sequence with a collection of LDSs, each one describing a small spatiotemporal patch extracted from the video. This Bag-of-Systems (BoS) representation is analogous to the Bag-of-Features (BoF) representation for object recognition, except that we use LDSs as feature descriptors. This choice poses several technical challenges in adopting the traditional BoF approach. Most notably, the space of LDSs is not euclidean; hence, novel methods for clustering LDSs and computing codewords of LDSs need to be developed. We propose a framework that makes use of nonlinear dimensionality reduction and clustering techniques combined with the Martin distance for LDSs to tackle these issues. Our experiments compare the proposed BoS approach to existing dynamic texture categorization methods and show that it can be used for recognizing dynamic textures in challenging scenarios which could not be handled by existing methods.

Acute enterocyte adaptation to luminal glucose: a posttranslational mechanism for rapid apical recruitment of the transporter GLUT2.

BACKGROUND: Glucose absorption postprandially increases markedly to levels far greater than possible by the classic glucose transporter sodium-glucose cotransporter 1 (SGLT1). HYPOTHESIS: Luminal concentrations of glucose >50 mM lead to rapid, phenotypic, non-genomic adaptations by the enterocyte to recruit another transporter, glucose transporter 2 (GLUT2), to the apical membrane to increase glucose absorption. METHODS: Isolated segments of jejunum were perfused in vivo with glucose-containing solutions in anesthetized rats. Carrier-mediated glucose uptake was measured in 10 and 100 mM glucose solutions (n = 6 rats each) with and without selective inhibitors of SGLT1 and GLUT2. RESULTS: The mean rate of carrier-mediated glucose uptake increased in rats perfused with 100 mM versus 10 mM glucose to 13.9 ± 2.9 µmol from 2.1 ± 0.1 µmol, respectively (p < 0.0001). Using selective inhibitors, the relative contribution of GLUT2 to glucose absorption was 56% in the 100 mM concentration of glucose compared to the 10 mM concentration (27%; p < 0.01). Passive absorption accounted for 6% of total glucose absorption at 100 mM glucose. CONCLUSION: A small amount of GLUT2 is active at the lesser luminal concentrations of glucose, but when exposed to concentrations of 100 mM, the enterocyte presumably changes its phenotype by recruiting GLUT2 apically to markedly augment glucose absorption.

Tumor characteristics and survival analysis of incidental versus suspected gallbladder carcinoma.

INTRODUCTION: Over half of all gallbladder carcinoma (GBC) is discovered incidentally after cholecystectomy for benign disease. There are scant data comparing presentation and outcome for patients with incidental versus suspected GBC. The goal of this study is to determine the clinical differences between these two entities. STUDY DESIGN: Patients with GBC were identified retrospectively from records at academic healthcare institutions in Temuco, Chile; Atlanta, GA; and Rochester, MN between 1984 and 2008. Overall survival was compared for patients with and without preoperative suspicion using Kaplan-Meier curves and a multivariate Cox proportional hazards model. RESULTS: Of 571 patients, 128 (22.4%) had preoperative suspicion of malignancy, and 443 (77.6 %) were discovered incidentally. Incidental tumors were of lower stage, better differentiated, and with lower rates of metastases. Median survival for incidentally discovered GBC was 32.3 versus 5.8 months for suspected GBC (p<0.0001). In a Cox proportional hazards model controlling for operation extent, T stage, differentiation, and other factors, preoperative suspicion remains a strong risk factor (odds ratio, 2.0; confidence interval, 1.5-2.9; p<0.0001). CONCLUSIONS: Tumor characteristics differed significantly between patients with incidentally discovered versus preoperatively suspected GBC. Incidental GBC has a significantly better median survival.

Intestinal adaptation for oligopeptide absorption via PepT1 after massive (70%) mid-small bowel resection.

INTRODUCTION: Proteins are absorbed primarily as short peptides via peptide transporter 1 (PepT1). HYPOTHESIS: Intestinal adaptation for peptide absorption after massive mid-small intestinal resection occurs by increased expression of PepT1 in the remnant small intestine and colon. METHODS: Peptide uptake was measured in duodenum, jejunum, ileum, and colon using glycyl-sarcosine 1 week (n = 9) and 4 weeks (n = 11) after 70% mid-small bowel resection and in corresponding segments from unoperated rats (n = 12) and after transection and reanastomosis of jejunum and ileum (n = 8). Expression of PepT1 (mRNA, protein) and villus height were measured. RESULTS: Intestinal transection/reanastomosis did not alter gene expression. Compared to non-operated controls, 70% mid-small bowel resection increased jejunal peptide uptake (p < 0.05) associated with increased villus height (1.13 vs 1.77 and 1.50 mm, respectively, p < 0.01). In ileum although villus height increased at 1 and 4 weeks (1.03 vs 1.21 and 1.35 mm, respectively; p < 0.01), peptide uptake was not altered. PepT1 mRNA and protein were decreased at 1 week, and PepT1 protein continued low at 4 weeks. Gene expression, peptide uptake, and histomorphology were unchanged in the colon. CONCLUSIONS: Jejunal adaptation for peptide absorption occurs by hyperplasia. Distal ileum and colon do not have a substantive role in adaptation for peptide absorption.