5-HT7 receptor-dependent intestinal neurite outgrowth contributes to visceral hypersensitivity in irritable bowel syndrome.

Irritable bowel syndrome (IBS) is characterized by visceral hypersensitivity (VH) associated with abnormal serotonin/5-hydroxytryptamine (5-HT) metabolism and neurotrophin-dependent mucosal neurite outgrowth. The underlying mechanisms of VH remain poorly understood. We investigated the role of 5-HT7 receptor in mucosal innervation and intestinal hyperalgesia. A high density of mucosal nerve fibres stained for 5-HT7 was observed in colonoscopic biopsy specimens from IBS patients compared with those from healthy controls. Staining of 5-HT3 and 5-HT4 receptors was observed mainly in colonic epithelia with comparable levels between IBS and controls. Visceromotor responses to colorectal distension were evaluated in two mouse models, one postinfectious with Giardia and subjected to water avoidance stress (GW) and the other postinflammatory with trinitrobenzene sulfonic acid-induced colitis (PT). Increased VH was associated with higher mucosal density of 5-HT7-expressing nerve fibres and elevated neurotrophin and neurotrophin receptor levels in the GW and PT mice. The increased VH was inhibited by intraperitoneal injection of SB-269970 (a selective 5-HT7 antagonist). Peroral multiple doses of CYY1005 (a novel 5-HT7 ligand) decreased VH and reduced mucosal density of 5-HT7-expressing nerve fibres in mouse colon. Human neuroblastoma SH-SY5Y cells incubated with bacteria-free mouse colonic supernatant, 5-HT, nerve growth factor, or brain-derived neurotrophic factor exhibited nerve fibre elongation, which was inhibited by 5-HT7 antagonists. Gene silencing of HTR7 also reduced the nerve fibre length. Activation of 5-HT7 upregulated NGF and BDNF gene expression, while stimulation with neurotrophins increased the levels of tryptophan hydroxylase 2 and 5-HT7 in neurons. A positive-feedback loop was observed between serotonin and neurotrophin pathways via 5-HT7 activation to aggravate fibre elongation, whereby 5-HT3 and 5-HT4 had no roles. In conclusion, 5-HT7-dependent mucosal neurite outgrowth contributed to VH. A novel 5-HT7 antagonist could be used as peroral analgesics for IBS-related pain.

A novel tumor suppressor role of myosin light chain kinase splice variants through downregulation of the TEAD4/CD44 axis.

Myosin light chain kinase (MLCK) regulates actinomyosin contraction. Two splice variants of long MLCK are expressed in epithelial cells and divergently regulate gut barrier functions; reduced MLCK levels in human colorectal cancers (CRC) with unclarified significance have been reported. CRC are solid tumors clonally sustained by stem cells highly expressing CD44 and CD133. The aim was to investigate the role of MLCK splice variants in CRC tumorigenesis. We found lower MLCK1/2 and higher CD44 expression in human CRC, but no change in CD133 or LGR5. Large-scale bioinformatics showed an inverse relationship between MYLK and CD44 in human sample gene datasets. A 3-fold increased tumor burden was observed in MLCK(-/-) mice compared with wild-type (WT) mice in a chemical-induced CRC model. Primary tumorspheres derived from the MLCK(-/-) mice displayed larger sizes and higher CD44 transcript levels than those from the WT mice. Bioinformatics revealed binding of TEAD4 (a transcriptional enhancer factor family member in the Hippo pathway) to CD44 promoter, which was confirmed by luciferase reporter assay. Individually expressing MLCK1 and MLCK2 variants in the MLCK-knockout (KO) Caco-2 cells inhibited the nuclear localization of TEAD4 cofactors, VGLL3 and YAP1, respectively, and both variants reduced the CD44 transcription. Accelerated cell cycle transit was observed in the MLCK-KO cells, whereby expression of MLCK1/2 variants counterbalanced the cell hyperproliferation. In conclusion, MLCK1/2 variants are novel tumor suppressors by downregulating the TEAD4/CD44 axis via reducing nuclear translocation of distinct transcriptional coactivators. The reduction of epithelial MLCKs, especially isoform 2, may drive cancer stemness and tumorigenesis.

Hypoxia-induced intestinal barrier changes in balloon-assisted enteroscopy.

KEY POINTS: Balloon-assisted enteroscopy (BAE) is an emerging standard procedure by utilizing distensible balloons to facilitate deep endoscopy in the small and large intestine. Sporadic cases of bacteraemia were found after BAE. Balloon distension by BAE caused gut tissue hypoxia. The impact of balloon distension-induced hypoxia on intestinal barriers remains unclear. Murine models of BAE by colonic balloon distension showed that short- and long-term hypoxia evoked opposite effects on epithelial tight junctions (TJs). Short-term hypoxia fortified TJ integrity, whereas long-term hypoxia caused damage to barrier function. Our data showed for the first time the molecular mechanisms and signalling pathways of epithelial barrier fortification and TJ reorganization by short-term hypoxia for the maintenance of gut homeostasis. The findings suggest avoiding prolonged balloon distension during BAE to reduce the risk of hypoxia-induced gut barrier dysfunction. ABSTRACT: Balloon-assisted enteroscopy (BAE) is an emerging standard procedure that uses distensible balloons to facilitate deep endoscopy. Intestines are known to harbour an abundant microflora. Whether balloon distension causes perturbation of blood flow and gut barrier dysfunction, and elicits risk of bacterial translocation remains unknown. Our aims were to (1) conduct a prospective study to gather microbiological and molecular evidence of bacterial translocation by BAE in patients, (2) establish a murine model of colonic balloon distension to investigate tissue hypoxia and intestinal barrier, and (3) assess the effect of short- and long-term hypoxia on epithelial permeability using cell lines. Thirteen patients were enrolled for BAE procedures, and blood samples were obtained before and after BAE for paired comparison. Four of the 13 patients (30.8%) had positive bacterial DNA in blood after BAE. Post-BAE endotoxaemia was higher than the pre-BAE level. Nevertheless, no clinical symptom of sepsis or fever was reported. To mimic clinical BAE, mice were subjected to colonic balloon distension. Local tissue hypoxia was observed during balloon inflation, and reoxygenation after deflation. A trend of increased gut permeability was seen after long-term distension, whereas a significant reduction of permeability was observed by short-term distension in the proximal colon. Human colonic epithelial Caco-2 cells exposed to hypoxia for 5-20 min exhibited increased tight junctional assembly, while those exposed to longer hypoxia displayed barrier disruption. In conclusion, sporadic cases of bacteraemia were found after BAE, without septic symptoms. Short-term hypoxia by balloon distension yielded a protective effect whereas long-term hypoxia caused damage to the gut barrier.

Computer-aided diagnosis for identifying and delineating early gastric cancers in magnifying narrow-band imaging.

BACKGROUND AND AIMS: Magnifying narrow-band imaging (M-NBI) is important in the diagnosis of early gastric cancers (EGCs) but requires expertise to master. We developed a computer-aided diagnosis (CADx) system to assist endoscopists in identifying and delineating EGCs. METHODS: We retrospectively collected and randomly selected 66 EGC M-NBI images and 60 non-cancer M-NBI images into a training set and 61 EGC M-NBI images and 20 non-cancer M-NBI images into a test set. After preprocessing and partition, we determined 8 gray-level co-occurrence matrix (GLCM) features for each partitioned 40 × 40 pixel block and calculated a coefficient of variation of 8 GLCM feature vectors. We then trained a support vector machine (SVMLv1) based on variation vectors from the training set and examined in the test set. Furthermore, we collected 2 determined P and Q GLCM feature vectors from cancerous image blocks containing irregular microvessels from the training set, and we trained another SVM (SVMLv2) to delineate cancerous blocks, which were compared with expert-delineated areas for area concordance. RESULTS: The diagnostic performance revealed accuracy of 96.3%, precision (positive predictive value [PPV]) of 98.3%, recall (sensitivity) of 96.7%, and specificity of 95%, at a rate of 0.41 ± 0.01 seconds per image. The performance of area concordance, on a block basis, demonstrated accuracy of 73.8% ± 10.9%, precision (PPV) of 75.3% ± 20.9%, recall (sensitivity) of 65.5% ± 19.9%, and specificity of 80.8% ± 17.1%, at a rate of 0.49 ± 0.04 seconds per image. CONCLUSIONS: This pilot study demonstrates that our CADx system has great potential in real-time diagnosis and delineation of EGCs in M-NBI images.

Distinct cytoprotective roles of pyruvate and ATP by glucose metabolism on epithelial necroptosis and crypt proliferation in ischaemic gut.

KEY POINTS: Intestinal ischaemia causes epithelial death and crypt dysfunction, leading to barrier defects and gut bacteria-derived septic complications. Enteral glucose protects against ischaemic injury; however, the roles played by glucose metabolites such as pyruvate and ATP on epithelial death and crypt dysfunction remain elusive. A novel form of necrotic death that involves the assembly and phosphorylation of receptor interacting protein kinase 1/3 complex was found in ischaemic enterocytes. Pyruvate suppressed epithelial cell death in an ATP-independent manner and failed to maintain crypt function. Conversely, replenishment of ATP partly restored crypt proliferation but had no effect on epithelial necroptosis in ischaemic gut. Our data argue against the traditional view of ATP as the main cytoprotective factor by glucose metabolism, and indicate a novel anti-necroptotic role of glycolytic pyruvate under ischaemic stress. ABSTRACT: Mesenteric ischaemia/reperfusion induces epithelial death in both forms of apoptosis and necrosis, leading to villus denudation and gut barrier damage. It remains unclear whether programmed cell necrosis [i.e. receptor-interacting protein kinase (RIP)-dependent necroptosis] is involved in ischaemic injury. Previous studies have demonstrated that enteral glucose uptake by sodium-glucose transporter 1 ameliorated ischaemia/reperfusion-induced epithelial injury, partly via anti-apoptotic signalling and maintenance of crypt proliferation. Glucose metabolism is generally assumed to be cytoprotective; however, the roles played by glucose metabolites (e.g. pyruvate and ATP) on epithelial cell death and crypt dysfunction remain elusive. The present study aimed to investigate the cytoprotective effects exerted by distinct glycolytic metabolites in ischaemic gut. Wistar rats subjected to mesenteric ischaemia were enterally instilled glucose, pyruvate or liposomal ATP. The results showed that intestinal ischaemia caused RIP1-dependent epithelial necroptosis and villus destruction accompanied by a reduction in crypt proliferation. Enteral glucose uptake decreased epithelial cell death and increased crypt proliferation, and ameliorated mucosal histological damage. Instillation of cell-permeable pyruvate suppressed epithelial cell death in an ATP-independent manner and improved the villus morphology but failed to maintain crypt function. Conversely, the administration of liposomal ATP partly restored crypt proliferation but did not reduce epithelial necroptosis and histopathological injury. Lastly, glucose and pyruvate attenuated mucosal-to-serosal macromolecular flux and prevented enteric bacterial translocation upon blood reperfusion. In conclusion, glucose metabolites protect against ischaemic injury through distinct modes and sites, including inhibition of epithelial necroptosis by pyruvate and the promotion of crypt proliferation by ATP.

Tumor Necrosis Factor α-Dependent Neutrophil Priming Prevents Intestinal Ischemia/Reperfusion-Induced Bacterial Translocation.

BACKGROUND: Intestinal ischemia/reperfusion (I/R) causes barrier impairment and bacterial influx. Protection against I/R injury in sterile organs by hypoxic preconditioning (HPC) had been attributed to erythropoietic and angiogenic responses. Our previous study showed attenuation of intestinal I/R injury by HPC for 21 days in a neutrophil-dependent manner. AIM: To investigate the underlying mechanisms of neutrophil priming by HPC, and explore whether adoptive transfer of primed neutrophils is sufficient to ameliorate intestinal I/R injury. METHODS: Rats raised in normoxia (NM) and HPC for 3 or 7 days were subjected to sham operation or superior mesenteric artery occlusion for I/R challenge. Neutrophils isolated from rats raised in NM or HPC for 21 days were intravenously injected into naïve controls prior to I/R. RESULTS: Similar to the protective effect of HPC-21d, I/R-induced mucosal damage was attenuated by HPC-7d but not by HPC-3d. Naïve rats reconstituted with neutrophils of HPC-21d rats showed increase in intestinal phagocytic infiltration and myeloperoxidase activity, and barrier protection against I/R insult. Elevated free radical production, and higher bactericidal and phagocytic activity were observed in HPC neutrophils compared to NM controls. Moreover, increased serum levels of tumor necrosis factor α (TNFα) and cytokine-induced neutrophil chemoattractant-1 (CINC-1) were seen in HPC rats. Naïve neutrophils incubated with HPC serum or recombinant TNFα, but not CINC-1, exhibited heightened respiratory burst and bactericidal activity. Lastly, neutrophil priming effect was abolished by neutralization of TNFα in HPC serum. CONCLUSIONS: TNFα-primed neutrophils by HPC act as effectors cells for enhancing barrier integrity under gut ischemia.

Gut-derived cholecystokinin contributes to visceral hypersensitivity via nerve growth factor-dependent neurite outgrowth.

BACKGROUND AND AIM: Irritable bowel syndrome is characterized by abdominal pain and altered bowel habits and may occur following stressful events or infectious gastroenteritis such as giardiasis. Recent findings revealed a link between cholecystokinin (CCK), neurotrophin synthesis, and intestinal hyperalgesia. The aim was to investigate the role of CCK in visceral hypersensitivity using mouse models challenged with a bout of infection with Giardia lamblia or psychological stress, either alone or in combination. METHODS: Abdominal pain was evaluated by visceromoter response to colorectal distension. Nerve fibers in intestinal tissues were stained using immunohistochemistry (PGP9.5). Human neuroblastoma SH-SY5Y cells incubated with bacterial-free mouse gut supernatant or recombinant CCK-8S were assessed for neurite outgrowth and nerve growth factor (NGF) production. RESULTS: Intestinal hypersensitivity was induced by either stress or Giardia infection, and a trend of increased pain was seen following dual stimuli. Increased CCK levels and PGP9.5 immunoreactivity were found in colonic mucosa of mice following stress and/or infection. Inhibitors to the CCK-A receptor (L-364718) or CCK-B receptor (L-365260) blocked visceral hypersensitivity caused by stress, but not when induced by giardiasis. Nerve fiber elongation and NGF synthesis were observed in SH-SY5Y cells after incubation with colonic supernatants from mice given the dual stimuli, or after treatment with CCK-8S. Increased nerve fiber length by colonic supernatant and CCK-8S was attenuated by L-365260 or neutralizing anti-NGF. CONCLUSIONS: This new model successfully recapitulates intestinal hypernociception induced by stress or Giardia. Colonic CCK contributes to visceral hypersensitivity caused by stress, but not by Giardia, partly via NGF-dependent neurite outgrowth.

Risk factors of short-term mortality after acute nonvariceal upper gastrointestinal bleeding in patients on dialysis: a population-based study.

BACKGROUND: Impaired kidney function is an established predictor of mortality after acute nonvariceal upper gastrointestinal bleeding (ANVUGIB); however, which factors are associated with mortality after ANVUGIB among patients undergoing dialysis is unknown. We examined the associations among demographic characteristics, dialysis-specific features, and comorbid conditions with short-term mortality after ANVUGIB among patients on dialysis. DESIGN: Retrospective cohort study. SETTING: United States Renal Data System (USRDS), a nation-wide registry of patients with end-stage renal disease. PARTICIPANTS: All ANVUGIB episodes identified by validated algorithms in Medicare-covered patients between 2003 and 2007. MEASUREMENTS: Demographic characteristics and comorbid conditions from 1 year of billing claims prior to each bleeding event. We used logistic regression extended with generalized estimating equations methods to model the associations among risk factors and 30-day mortality following ANVUGIB events. RESULTS: From 2003 to 2007, we identified 40,016 eligible patients with 50,497 episodes of ANVUGIB. Overall 30-day mortality was 10.7% (95% CI: 10.4-11.0). Older age, white race, longer dialysis vintage, peritoneal dialysis (vs. hemodialysis), and hospitalized (vs. outpatient) episodes were independently associated with a higher risk of 30-day mortality. Most but not all comorbid conditions were associated with death after ANVUGIB. The joint ability of all factors captured to discriminate mortality was modest (c=0.68). CONCLUSIONS: We identified a profile of risk factors for 30-day mortality after ANVUGIB among patients on dialysis that was distinct from what had been reported in non-dialysis populations. Specifically, peritoneal dialysis and more years since initiation of dialysis were independently associated with short-term death after ANVUGIB.

Trends in acute nonvariceal upper gastrointestinal bleeding in dialysis patients.

Impaired kidney function is a risk factor for upper gastrointestinal (GI) bleeding, an event associated with poor outcomes. The burden of upper GI bleeding and its effect on patients with ESRD are not well described. Using data from the US Renal Data System, we quantified the rates of occurrence of and associated 30-day mortality from acute, nonvariceal upper GI bleeding in patients undergoing dialysis; we used medical claims and previously validated algorithms where available. Overall, 948,345 patients contributed 2,296,323 patient-years for study. The occurrence rates for upper GI bleeding were 57 and 328 episodes per 1000 person-years according to stringent and lenient definitions of acute, nonvariceal upper GI bleeding, respectively. Unadjusted occurrence rates remained flat (stringent) or increased (lenient) from 1997 to 2008; after adjustment for sociodemographic characteristics and comorbid conditions, however, we found a significant decline for both definitions (linear approximation, 2.7% and 1.5% per year, respectively; P<0.001). In more recent years, patients had higher hematocrit levels before upper GI bleeding episodes and were more likely to receive blood transfusions during an episode. Overall 30-day mortality was 11.8%, which declined significantly over time (relative declines of 2.3% or 2.8% per year for the stringent and lenient definitions, respectively). In summary, despite declining trends worldwide, crude rates of acute, nonvariceal upper GI bleeding among patients undergoing dialysis have not decreased in the past 10 years. Although 30-day mortality related to upper GI bleeding declined, perhaps reflecting improvements in medical care, the burden on the ESRD population remains substantial.

Multi-head self-attention mechanism enabled individualized hemoglobin prediction and treatment recommendation systems in anemia management for hemodialysis patients.

Anemia is a critical complication in hemodialysis patients, but the response to erythropoietin-stimulating agents (ESA) treatment varies from patient to patient and is not linear across different time points. The aim of this study was to develop deep learning algorithms for individualized anemia management. We retrospectively collected 36,677 data points from 623 hemodialysis patients, including clinical data, laboratory values, hemoglobin levels, and previous ESA doses. To reduce the computational complexity associated with recurrent neural networks (RNN) in processing time-series data, we developed neural networks based on multi-head self-attention mechanisms in an efficient and effective hemoglobin prediction model. Our proposed model achieved a more accurate hemoglobin prediction than the state-of-the-art RNN model, as shown by the smaller mean absolute error (MAE) of hemoglobin (0.451 vs. 0.593 g/dL, p = 0.014). In ESA (including darbepoetin and epoetin) dose recommendation, the simulation results by our model revealed a higher rate of achieved hemoglobin targets (physician prescription vs. model: 86.3 % vs. 92.7 %, p < 0.001), a lower rate of hemoglobin levels below 10 g/dL (13.7 % vs. 7.3 %, p < 0.001) and smaller change in hemoglobin levels (0.6 g/dL vs. 0.4 g/dL, p < 0.001) in all patients. Our model holds great potential for individualized anemia management as a computerized clinical decision support system for hemodialysis patients. Further external validation with other datasets and prospective clinical utility studies are warranted.

Deep-Learning-Enabled Computer-Aided Diagnosis in the Classification of Pancreatic Cystic Lesions on Confocal Laser Endomicroscopy.

Accurate classification of pancreatic cystic lesions (PCLs) is important to facilitate proper treatment and to improve patient outcomes. We utilized the convolutional neural network (CNN) of VGG19 to develop a computer-aided diagnosis (CAD) system in the classification of subtypes of PCLs in endoscopic ultrasound-guided needle-based confocal laser endomicroscopy (nCLE). From a retrospectively collected 22,424 nCLE video frames (50 videos) as the training/validation set and 11,047 nCLE video frames (18 videos) as the test set, we developed and compared the diagnostic performance of three CNNs with distinct methods of designating the region of interest. The diagnostic accuracy for subtypes of PCLs by CNNs with manual, maximal rectangular, and U-Net algorithm-designated ROIs was 100%, 38.9%, and 66.7% on a per-video basis and 88.99%, 73.94%, and 76.12% on a per-frame basis, respectively. Our per-frame analysis suggested differential levels of diagnostic accuracy among the five subtypes of PCLs, where non-mucinous PCLs (serous cystic neoplasm: 93.11%, cystic neuroendocrine tumor: 84.31%, and pseudocyst: 98%) had higher diagnostic accuracy than mucinous PCLs (intraductal papillary mucinous neoplasm: 84.43% and mucinous cystic neoplasm: 86.1%). Our CNN demonstrated superior specificity compared to the state-of-the-art for the classification of mucinous PCLs (IPMN and MCN), with high specificity (94.3% and 92.8%, respectively) but low sensitivity (46% and 45.2%, respectively). This suggests the complimentary role of CNN-enabled CAD systems, especially for clinically suspected mucinous PCLs.

Neutrophil priming by hypoxic preconditioning protects against epithelial barrier damage and enteric bacterial translocation in intestinal ischemia/reperfusion.

Intestinal ischemia/reperfusion (I/R) induces mucosal barrier dysfunction and bacterial translocation (BT). Neutrophil-derived oxidative free radicals have been incriminated in the pathogenesis of ischemic injury in various organs, but their role in the bacteria-containing intestinal tract is debatable. Primed neutrophils are characterized by a faster and higher respiratory burst activity associated with more robust bactericidal effects on exposure to a second stimulus. Hypoxic preconditioning (HPC) attenuates ischemic injury in brain, heart, lung and kidney; no reports were found in the gut. Our aim is to investigate whether neutrophil priming by HPC protects against intestinal I/R-induced barrier damage and bacterial influx. Rats were raised in normoxia (NM) or kept in a hypobaric hypoxic chamber (380 Torr) 17 h/day for 3 weeks for HPC, followed by sham operation or intestinal I/R. Gut permeability was determined by using an ex vivo macromolecular flux assay and an in vivo magnetic resonance imaging-based method. Liver and spleen homogenates were plated for bacterial culturing. Rats raised in HPC showed diminished levels of BT, and partially improved mucosal histopathology and epithelial barrier function compared with the NM groups after intestinal I/R. Augmented cytokine-induced neutrophil chemoattractant (CINC)-1 and -3 levels and myeloperoxidase activity correlated with enhanced infiltration of neutrophils in intestines of HPC-I/R compared with NM-I/R rats. HPC alone caused blood neutrophil priming, as shown by elevated production of superoxide and hydrogen peroxide on stimulation, increased membrane translocation of cytosolic p47(phox) and p67(phox), as well as augmented bacterial-killing and phagocytotic activities. Neutrophil depletion reversed the mucosal protection by HPC, and aggravated intestinal leakiness and BT following I/R. In conclusion, neutrophil priming by HPC protects against I/R-induced BT via direct antimicrobial activity by oxidative respiratory bursts and through promotion of epithelial barrier integrity for luminal confinement of enteric bacteria.

Anti-apoptotic PI3K/Akt signaling by sodium/glucose transporter 1 reduces epithelial barrier damage and bacterial translocation in intestinal ischemia.

Intestinal ischemia/reperfusion (I/R) causes mucosal barrier damage and bacterial translocation (BT), leading to septic complications. Previous in vitro studies showed that activation of sodium/glucose transporter 1 (SGLT1) prevented the epithelial apoptosis and permeability rise induced by microbial products. Our aim was to investigate whether luminal glucose uptake by SGLT1 protects against ischemia-induced epithelial cell death and barrier dysfunction, and to explore the glucose-mediated cellular survival pathways in vivo. Rat jejunum was luminally instilled with either vehicle, a pancaspase inhibitor ZVAD, or glucose prior to I/R challenge (occlusion of the superior mesenteric artery for 20 min and reperfusion for 60 min). Histopathology and apoptosis in the jejunum were examined by TUNEL staining and caspase-3 cleavage. Intestinal permeability was evaluated using in vivo assays measuring luminal-to-blood passage of fluorescein-dextran and portal drainage of enterally administered gadodiamide by magnetic resonance imaging. BT was determined by culturing liver and spleen homogenates. Immunofluorescent analysis and kinase assay were used to study PI3K/Akt signaling pathways. Intestinal I/R caused enterocyte apoptosis and villous destruction. Intestinal infusion with ZVAD decreased the I/R-triggered gut permeability rise and BT, suggesting that the barrier damage was partly dependent on cell apoptosis. Enteral instillation of glucose attenuated the epithelial apoptosis, barrier damage, and mucosal inflammation caused by I/R. Phloridzin (a SGLT1 inhibitor) reduced the protective effect of glucose in a dose-dependent manner. Enteral glucose increased the mucosal Akt kinase activity as evidenced by the augmented phosphorylation of exogenous GSK3. Enhanced membrane translocation and phosphorylation of Akt in epithelial cells were associated with elevated phosphorylation of mTOR, Bad, and FoxO1/3a following glucose uptake. Inhibition of PI3K/Akt signaling by LY294002 and wortmannin partially blocked the glucose-mediated rescue of cell apoptosis and barrier damage. In conclusion, SGLT1 glucose uptake alleviated I/R-induced barrier dysfunction and BT, partly by inhibiting epithelial apoptosis via activation of PI3K/Akt signaling.

Male gender and renal dysfunction are predictors of adverse outcome in nonpostoperative ischemic colitis patients.

OBJECTIVE: Ischemic colitis (IC) spans a broad spectrum from self-limiting illness to intestinal gangrene and mortality. Prognostic factors specifically for nonpostoperative IC were not fully characterized. We aim to focus on nonpostoperative IC in patients with renal dysfunction and try to identify prognostic factors for adverse outcomes. METHODS: We conducted a retrospective analysis at a university-affiliated tertiary medical center in Taiwan. From January 2003 to August 2008, 25 men and 52 women (mean age: 66 y) had colonoscopic biopsy-proven IC without prior culprit surgery. We estimated glomerular filtration rate with simplified Modification of Diet in Renal Disease equation. Nine patients with glomerular filtration rate below 30 mL per minute per 1.73 m were classified as renal dysfunction group (including 7 dialysis patients). Adverse outcomes were defined as need for surgery and mortality. Predictors for adverse outcomes were captured by univariate and multivariate analysis. Research ethical committee approved the study protocol. RESULTS: Patients with renal dysfunction more often had: diabetes mellitus (56% vs. 16%, P=0.02), prolonged symptoms (6.8 d vs. 3.5 d, P=0.01), lower hemoglobin (11.1 g/dL vs. 13.4 g/dL, P=0.01), and more often right colonic involvement (56% vs. 19%, P=0.03). Renal dysfunction patients also had longer hospitalization days (median 15 d vs. 4 d, P=0.045). However, there was no statistical significance in the rate of either surgery or mortality between these 2 groups (P>0.05). Univariate analysis showed that renal dysfunction, sex, emergency department referral, presentation with abdominal pain were significant for adverse outcome (P<0.1). Multivariate analysis revealed that male sex conveyed 9.5-fold risk (P=0.01) and renal dysfunction conveyed 8.5-fold risk (P=0.03) for adverse outcomes. CONCLUSIONS: Nonpostoperative IC patients with concurrent renal dysfunction had distinct clinical profiles. Multivariate analysis showed that male patients had 9.5-fold and renal dysfunction patients had 8.5-fold increased risk for adverse outcomes. Although IC is often self-limited, our data warrants special attention and aggressive therapy in treating these patients.

Glucose Metabolites Exert Opposing Roles in Tumor Chemoresistance.

Reprogrammed glucose metabolism and increased glycolysis have been implicated in tumor chemoresistance. The aim was to investigate the distinct roles of the glucose metabolites pyruvate and ATP in chemoresistance mechanisms, including cell death and proliferation. Our data showed higher glucose transporters in colorectal cancer (CRC) from non-responsive patients than those responsive to chemotherapy. Human CRC cell lines exposed to 5-fluorouracil (5-FU) displayed elevated cell viability and larger tumors in xenograft mouse models if cultured in high-glucose medium. Glucose conferred resistance to 5-FU-induced necroptosis via pyruvate scavenging of mitochondrial free radicals, whereas ATP replenishment had no effect on cell death. Glucose attenuated the 5-FU-induced G0/G1 shift but not the S phase arrest. Opposing effects were observed by glucose metabolites; ATP increased while pyruvate decreased the G0/G1 shift. Lastly, 5-FU-induced tumor spheroid destruction was prevented by glucose and pyruvate, but not by ATP. Our finding argues against ATP as the main effector for glucose-mediated chemoresistance and supports a key role of glycolytic pyruvate as an antioxidant for dual modes of action: necroptosis reduction and a cell cycle shift to a quiescent state.

Peritoneal thickening is not inevitable in long-term peritoneal dialysis and is associated with peritoneal transport characteristics: a two-centre sonographic study.

BACKGROUND: The peritoneum is subject to alterations in the life-long course of peritoneal dialysis (PD). Studies of the parietal peritoneum by non-invasive ultrasonography in PD patients are limited. We hypothesize that a prolonged PD duration is associated with a thicker peritoneum on ultrasonography and alterations in Doppler indexes of mesenteric vessels. METHODS: We recruited two groups of patients, 18 who had >7 years of PD and 18 who had <12 months of PD. We excluded patients with active peritonitis, history of major abdominal surgery, cirrhosis or malignancy. We measured the sonographic thickness of the parietal peritoneum and Doppler indexes of mesenteric vessels by trans-abdominal ultrasonography at two PD units in Taiwan. RESULTS: We found no significant difference between two groups of PD patients in peritoneal thickness and in Doppler indexes. However, our univariate and multivariate analysis indicated that peritoneal thickness is associated with peritoneal transport characteristics (dialysate/plasma creatinine) but not with age, duration of dialysis, body height, body weight or Doppler index. The peritoneum is significantly thicker in rapid transporters than in slow transporters (RUQ: 0.59 +/- 0.40 mm versus 0.27 +/- 0.29 mm, P = 0.01; LUQ: 0.60 +/- 0.40 mm versus 0.27 +/- 0.32 mm, P = 0.016; LQ: 1.07 +/- 0.85 mm versus 0.48 +/- 0.53 mm, P = 0.026). In addition, rapid transporters have a marginally lower Doppler resistive index of the superior mesenteric artery (0.87 +/- 0.08 versus 0.90 +/- 0.10, P = 0.028). CONCLUSIONS: Our data showed that peritoneal thickening is not inevitable in long-term PD patients. Sonographic thickness in the parietal peritoneum is associated with transport characteristics. Rapid transporters have a significantly thicker peritoneum. The Doppler index of mesenteric vessels had no association with PD duration or transport characteristics. Trans-abdominal ultrasonography is non-invasive and useful in evaluating peritoneal characteristics of PD patients.

Age is not a discriminating factor for outcomes of therapeutic upper gastrointestinal endoscopy.

BACKGROUND/AIMS: To compare the efficacy and complications of therapeutic endoscopy for acute nonvariceal upper gastrointestinal bleeding between the geriatric (aged 65 and older) and non-geriatric patients. METHODOLOGY: A total of 134 out of 259 hospitalized patients in the year 2005 had high-risk endoscopic lesions in UGI endoscopy and received therapeutic endoscopy. Seventy-six out of 134 patients were aged 65 and older (44 men), while 58 patients were aged 64 and younger (51 men). We compared clinical presentations, co-morbidities, endoscopic therapeutic procedures, endoscopic treatment failure, hospitalization days, blood transfusion, post-endoscopy complications (fever, acute coronary syndrome, aspiration pneumonia), and in-hospital mortality after therapeutic endoscopy. RESULTS: Geriatric patients had lower hemoglobin on arrival (9.19 +/- 2.7 vs. 10.64 +/- 2.46 g/dL, p = 0.002) and larger gastric ulcers (7.3 +/- 6.9 vs. 4.0 +/- 3.6 mm, p = 0.008). Failure of therapeutic endoscopy, defined as salvage endoscopy or surgery within 48 hours after first endoscopy, showed no difference (14% vs. 14%, p = 0.98). Hospitalization stay (mean 7.47 vs. 5.97 days, p = 0.2), blood transfusion more than 4 units (47% vs. 34%, p = 0.13), post-endoscopic complications, in-hospital mortality were all comparable between geriatrics and non-geriatrics. CONCLUSIONS: Our results serve a scientific basis that age is not a discriminating factor for outcomes in current therapeutic endoscopy.