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PubMed Central (PMC3 - NLM DTD) (2,928,005 recursos)
Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).

American Journal of Physiology - Gastrointestinal and Liver Physiology

Mostrando recursos 1 - 20 de 966

1. Activation of the renin-angiotensin system stimulates biliary hyperplasia during cholestasis induced by extrahepatic bile duct ligation - Afroze, Syeda H.; Munshi, Md Kamruzzaman; Martínez, Allyson K.; Uddin, Mohammad; Gergely, Maté; Szynkarski, Claudia; Guerrier, Micheleine; Nizamutdinov, Damir; Dostal, David; Glaser, Shannon
Cholangiocyte proliferation is regulated in a coordinated fashion by many neuroendocrine factors through autocrine and paracrine mechanisms. The renin-angiotensin system (RAS) is known to play a role in the activation of hepatic stellate cells and blocking the RAS attenuates hepatic fibrosis. We investigated the role of the RAS during extrahepatic cholestasis induced by bile duct ligation (BDL). In this study, we used normal and BDL rats that were treated with control, angiotensin II (ANG II), or losartan for 2 wk. In vitro studies were performed in a primary rat cholangiocyte cell line (NRIC). The expression of renin, angiotensin-converting enzyme, angiotensinogen,...

2. CXC chemokine receptor-4 signaling limits hepatocyte proliferation after hepatic ischemia-reperfusion in mice - Wilson, Gregory C.; Freeman, Christopher M.; Kuethe, Joshua W.; Quillin, Ralph C.; Nojima, Hiroyuki; Schuster, Rebecca; Blanchard, John; Edwards, Michael J.; Caldwell, Charles C.; Lentsch, Alex B.
The role of stromal cell-derived factor-1 (SDF-1 or CXCL12) and its receptor CXC chemokine receptor-4 (CXCR4) in ischemic liver injury and recovery has not been studied. Some reports suggest that this chemokine may aid in liver regeneration, but others suggest that it may be profibrotic through its activation of hepatic stellate cells. In this study we sought to elucidate the role of SDF-1 and its receptor CXCR4 during liver injury, recovery, and regeneration after ischemia-reperfusion (I/R). A murine model of partial (70%) I/R was used to induce liver injury and study the reparative and regenerative response. CXCR4 was expressed constitutively...

3. Validation of a rapid, semiautomatic image analysis tool for measurement of gastric accommodation and emptying by magnetic resonance imaging - Banerjee, Sreerup; Dixit, Sudeepa; Fox, Mark; Pal, Anupam
Magnetic resonance imaging (MRI) has advantages for the assessment of gastrointestinal structures and functions; however, processing MRI data is time consuming and this has limited uptake to a few specialist centers. This study introduces a semiautomatic image processing system for rapid analysis of gastrointestinal MRI. For assessment of simpler regions of interest (ROI) such as the stomach, the system generates virtual images along arbitrary planes that intersect the ROI edges in the original images. This generates seed points that are joined automatically to form contours on each adjacent two-dimensional image and reconstructed in three dimensions (3D). An alternative thresholding approach...

4. Human and mouse tissue-engineered small intestine both demonstrate digestive and absorptive function - Grant, Christa N.; Mojica, Salvador Garcia; Sala, Frederic G.; Hill, J. Ryan; Levin, Daniel E.; Speer, Allison L.; Barthel, Erik R.; Shimada, Hiroyuki; Zachos, Nicholas C.; Grikscheit, Tracy C.
Short bowel syndrome (SBS) is a devastating condition in which insufficient small intestinal surface area results in malnutrition and dependence on intravenous parenteral nutrition. There is an increasing incidence of SBS, particularly in premature babies and newborns with congenital intestinal anomalies. Tissue-engineered small intestine (TESI) offers a therapeutic alternative to the current standard treatment, intestinal transplantation, and has the potential to solve its biggest challenges, namely donor shortage and life-long immunosuppression. We have previously demonstrated that TESI can be generated from mouse and human small intestine and histologically replicates key components of native intestine. We hypothesized that TESI also recapitulates...

5. Fibroblast growth factor 10 alters the balance between goblet and Paneth cells in the adult mouse small intestine - Al Alam, Denise; Danopoulos, Soula; Schall, Kathy; Sala, Frederic G.; Almohazey, Dana; Fernandez, G. Esteban; Georgia, Senta; Frey, Mark R.; Ford, Henri R.; Grikscheit, Tracy; Bellusci, Saverio
Intestinal epithelial cell renewal relies on the right balance of epithelial cell migration, proliferation, differentiation, and apoptosis. Intestinal epithelial cells consist of absorptive and secretory lineage. The latter is comprised of goblet, Paneth, and enteroendocrine cells. Fibroblast growth factor 10 (FGF10) plays a central role in epithelial cell proliferation, survival, and differentiation in several organs. The expression pattern of FGF10 and its receptors in both human and mouse intestine and their role in small intestine have yet to be investigated. First, we analyzed the expression of FGF10, FGFR1, and FGFR2, in the human ileum and throughout the adult mouse small...

6. Inflammasomes in pancreatic physiology and disease - Hoque, Rafaz; Mehal, Wajahat Z.
In this review we summarize the role of inflammasomes in pancreatic physiology and disease with a focus on acute pancreatitis where much recent progress has been made. New findings have identified inducers of and cell specificity of inflammasome component expression in the pancreas, the contribution of inflammasome-regulated effectors to pancreatitis, and metabolic regulation of inflammasome activation, which are strong determinants of injury in pancreatitis. New areas of pancreatic biology will be highlighted in the context of our evolving understanding of gut microbiome- and injury-induced inflammasome priming, pyroptosis, and innate immune-mediated regulation of cell metabolism.

7. Effects of obesity on severity of colitis and cytokine expression in mouse mesenteric fat. Potential role of adiponectin receptor 1 - Sideri, Aristea; Stavrakis, Dimitris; Bowe, Collin; Shih, David Q.; Fleshner, Phillip; Arsenescu, Violeta; Arsenescu, Razvan; Turner, Jerrold R.; Pothoulakis, Charalabos; Karagiannides, Iordanes
In inflammatory bowel disease (IBD), obesity is associated with worsening of the course of disease. Here, we examined the role of obesity in the development of colitis and studied mesenteric fat-epithelial cell interactions in patients with IBD. We combined the diet-induce obesity with the trinitrobenzene sulfonic acid (TNBS) colitis mouse model to create groups with obesity, colitis, and their combination. Changes in the mesenteric fat and intestine were assessed by histology, myeloperoxidase assay, and cytokine mRNA expression by real-time PCR. Medium from human mesenteric fat and cultured preadipocytes was obtained from obese patients and those with IBD. Histological analysis showed...

8. Role of SM22 in the differential regulation of phasic vs. tonic smooth muscle - Rattan, Satish; Ali, Mehboob
Preliminary proteomics studies between tonic vs. phasic smooth muscles identified three distinct protein spots identified to be those of transgelin (SM22). The latter was found to be distinctly downregulated in the internal anal sphincter (IAS) vs. rectal smooth muscle (RSM) SMC. The major focus of the present studies was to examine the differential molecular control mechanisms by SM22 in the functionality of truly tonic smooth muscle of the IAS vs. the adjoining phasic smooth muscle of the RSM. We monitored SMC lengths before and after incubation with pFLAG-SM22 (for SM22 overexpression), and SM22 small-interfering RNA. pFLAG-SM22 caused concentration-dependent and significantly...

9. Apolipoprotein A-V deficiency enhances chylomicron production in lymph fistula mice - Zhang, Linda S.; Xu, Min; Yang, Qing; Ryan, Robert O.; Howles, Philip; Tso, Patrick
Apolipoprotein A-V (apoA-V), a liver-synthesized apolipoprotein discovered in 2001, strongly modulates fasting plasma triglycerides (TG). Little is reported on the effect of apoA-V on postprandial plasma TG, an independent predictor for atherosclerosis. Overexpressing apoA-V in mice suppresses postprandial TG, but mechanisms focus on increased lipolysis or clearance of remnant particles. Unknown is whether apoA-V suppresses the absorption of dietary lipids by the gut. This study examines how apoA-V deficiency affects the steady-state absorption and lymphatic transport of dietary lipids in chow-fed mice. Using apoA-V knockout (KO, n = 8) and wild-type (WT, n = 8) lymph fistula mice, we analyzed...

10. Human Clostridium difficile infection: altered mucus production and composition - Engevik, Melinda A.; Yacyshyn, Mary Beth; Engevik, Kristen A.; Wang, Jiang; Darien, Benjamin; Hassett, Daniel J.; Yacyshyn, Bruce R.; Worrell, Roger T.
The majority of antibiotic-induced diarrhea is caused by Clostridium difficile (C. difficile). Hospitalizations for C. difficile infection (CDI) have tripled in the last decade, emphasizing the need to better understand how the organism colonizes the intestine and maintain infection. The mucus provides an interface for bacterial-host interactions and changes in intestinal mucus have been linked host health. To assess mucus production and composition in healthy and CDI patients, the main mucins MUC1 and MUC2 and mucus oligosaccharides were examined. Compared with healthy subjects, CDI patients demonstrated decreased MUC2 with no changes in surface MUC1. Although MUC1 did not change at...

11. Human Clostridium difficile infection: inhibition of NHE3 and microbiota profile - Engevik, Melinda A.; Engevik, Kristen A.; Yacyshyn, Mary Beth; Wang, Jiang; Hassett, Daniel J.; Darien, Benjamin; Yacyshyn, Bruce R.; Worrell, Roger T.
Clostridium difficile infection (CDI) is principally responsible for hospital acquired, antibiotic-induced diarrhea and colitis and represents a significant financial burden on our healthcare system. Little is known about C. difficile proliferation requirements, and a better understanding of these parameters is critical for development of new therapeutic targets. In cell lines, C. difficile toxin B has been shown to inhibit Na+/H+ exchanger 3 (NHE3) and loss of NHE3 in mice results in an altered intestinal environment coupled with a transformed gut microbiota composition. However, this has yet to be established in vivo in humans. We hypothesize that C. difficile toxin inhibits...

12. Transcriptional corepressor MTG16 regulates small intestinal crypt proliferation and crypt regeneration after radiation-induced injury - Poindexter, Shenika V.; Reddy, Vishruth K.; Mittal, Mukul K.; Williams, Amanda M.; Washington, M. Kay; Harris, Elizabeth; Mah, Amanda; Hiebert, Scott W.; Singh, Kshipra; Chaturvedi, Rupesh; Wilson, Keith T.; Lund, P. Kay; Williams, Christopher S.
Myeloid translocation genes (MTGs) are transcriptional corepressors implicated in development, malignancy, differentiation, and stem cell function. While MTG16 loss renders mice sensitive to chemical colitis, the role of MTG16 in the small intestine is unknown. Histological examination revealed that Mtg16−/− mice have increased enterocyte proliferation and goblet cell deficiency. After exposure to radiation, Mtg16−/− mice exhibited increased crypt viability and decreased apoptosis compared with wild-type (WT) mice. Flow cytometric and immunofluorescence analysis of intestinal epithelial cells for phospho-histone H2A.X also indicated decreased DNA damage and apoptosis in Mtg16−/− intestines. To determine if Mtg16 deletion affected epithelial cells in a cell-autonomous...

13. Chronic NOS inhibition accelerates NAFLD progression in an obese rat model - Sheldon, Ryan D.; Padilla, Jaume; Jenkins, Nathan T.; Laughlin, M. Harold; Rector, R. Scott
The progression in nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis is a serious health concern, but the underlying mechanisms remain unclear. We hypothesized that chronic inhibition of nitric oxide (NO) synthase (NOS) via Nω-nitro-l-arginine methyl ester (l-NAME) would intensify liver injury in a rat model of obesity, insulin resistance, and NAFLD. Obese Otsuka Long-Evans Tokushima fatty (OLETF) and lean Long-Evans Tokushima Otsuka (LETO) rats received control or l-NAME (65–70 mg·kg−1·day−1)-containing drinking water for 4 wk. l-NAME treatment significantly (P < 0.05) reduced serum NO metabolites and food intake in both groups. Remarkably, despite no increase in body weight, l-NAME...

14. TRPM8 function and expression in vagal sensory neurons and afferent nerves innervating guinea pig esophagus - Yu, Xiaoyun; Hu, Youtian; Ru, Fei; Kollarik, Marian; Undem, Bradley J.; Yu, Shaoyong
Sensory transduction in esophageal afferents requires specific ion channels and receptors. TRPM8 is a new member of the transient receptor potential (TRP) channel family and participates in cold- and menthol-induced sensory transduction, but its role in visceral sensory transduction is still less clear. This study aims to determine TRPM8 function and expression in esophageal vagal afferent subtypes. TRPM8 agonist WS-12-induced responses were first determined in nodose and jugular neurons by calcium imaging and then investigated by whole cell patch-clamp recordings in Dil-labeled esophageal nodose and jugular neurons. Extracellular single-unit recordings were performed in nodose and jugular C fiber neurons using...

15. Allergen challenge sensitizes TRPA1 in vagal sensory neurons and afferent C-fiber subtypes in guinea pig esophagus - Liu, Zhenyu; Hu, Youtian; Yu, Xiaoyun; Xi, Jiefeng; Fan, Xiaoming; Tse, Chung-Ming; Myers, Allen C.; Pasricha, Pankaj J.; Li, Xingde; Yu, Shaoyong
Transient receptor potential A1 (TRPA1) is a newly defined cationic ion channel, which selectively expresses in primary sensory afferent nerve, and is essential in mediating inflammatory nociception. Our previous study demonstrated that TRPA1 plays an important role in tissue mast cell activation-induced increase in the excitability of esophageal vagal nodose C fibers. The present study aims to determine whether prolonged antigen exposure in vivo sensitizes TRPA1 in a guinea pig model of eosinophilic esophagitis (EoE). Antigen challenge-induced responses in esophageal mucosa were first assessed by histological stains and Ussing chamber studies. TRPA1 function in vagal sensory neurons was then studied...

16. ApoA-IV: current and emerging roles in intestinal lipid metabolism, glucose homeostasis, and satiety - Kohan, Alison B.; Wang, Fei; Lo, Chun-Min; Liu, Min; Tso, Patrick
Apolipoprotein A-IV (apoA-IV) is secreted by the small intestine on chylomicrons into intestinal lymph in response to fat absorption. Many physiological functions have been ascribed to apoA-IV, including a role in chylomicron assembly and lipid metabolism, a mediator of reverse-cholesterol transport, an acute satiety factor, a regulator of gastric function, and, finally, a modulator of blood glucose homeostasis. The purpose of this review is to update our current view of intestinal apoA-IV synthesis and secretion and the physiological roles of apoA-IV in lipid metabolism and energy homeostasis, and to underscore the potential for intestinal apoA-IV to serve as a therapeutic...

17. Giardia duodenalis-induced alterations of commensal bacteria kill Caenorhabditis elegans: a new model to study microbial-microbial interactions in the gut - Gerbaba, Teklu K.; Gupta, Pratyush; Rioux, Kevin; Hansen, Dave; Buret, Andre G.
Giardia duodenalis is the most common cause of parasitic diarrhea worldwide and a well-established risk factor for postinfectious irritable bowel syndrome. We hypothesized that Giardia-induced disruptions in host-microbiota interactions may play a role in the pathogenesis of giardiasis and in postgiardiasis disease. Functional changes induced by Giardia in commensal bacteria and the resulting effects on Caenorhabditis elegans were determined. Although Giardia or bacteria alone did not affect worm viability, combining commensal Escherichia coli bacteria with Giardia became lethal to C. elegans. Giardia also induced killing of C. elegans with attenuated Citrobacter rodentium espF and map mutant strains, human microbiota from...

18. Animal models of gastrointestinal and liver diseases. Animal models of cystic fibrosis: gastrointestinal, pancreatic, and hepatobiliary disease and pathophysiology - Olivier, Alicia K.; Gibson-Corley, Katherine N.; Meyerholz, David K.
Multiple organ systems, including the gastrointestinal tract, pancreas, and hepatobiliary systems, are affected by cystic fibrosis (CF). Many of these changes begin early in life and are difficult to study in young CF patients. Recent development of novel CF animal models has expanded opportunities in the field to better understand CF pathogenesis and evaluate traditional and innovative therapeutics. In this review, we discuss manifestations of CF disease in gastrointestinal, pancreatic, and hepatobiliary systems of humans and animal models. We also compare the similarities and limitations of animal models and discuss future directions for modeling CF.

19. Interaction between hydrogen sulfide-induced sulfhydration and tyrosine nitration in the KATP channel complex - Kang, Minho; Hashimoto, Atsushi; Gade, Aravind; Akbarali, Hamid I.
Hydrogen sulfide (H2S) is an endogenous gaseous mediator affecting many physiological and pathophysiological conditions. Enhanced expression of H2S and reactive nitrogen/oxygen species (RNS/ROS) during inflammation alters cellular excitability via modulation of ion channel function. Sulfhydration of cysteine residues and tyrosine nitration are the posttranslational modifications induced by H2S and RNS, respectively. The objective of this study was to define the interaction between tyrosine nitration and cysteine sulfhydration within the ATP-sensitive K+ (KATP) channel complex, a significant target in experimental colitis. A modified biotin switch assay was performed to determine sulfhydration of the KATP channel subunits, Kir6.1, sulphonylurea 2B (SUR2B), and...

20. Role of Fn14 in acute alcoholic steatohepatitis in mice - Karaca, Gamze; Xie, Guanhua; Moylan, Cynthia; Swiderska-Syn, Marzena; Guy, Cynthia D.; Krüger, Leandi; Machado, Mariana Verdelho; Choi, Steve S.; Michelotti, Gregory A.; Burkly, Linda C.; Diehl, Anna Mae
TNF-like weak inducer of apoptosis (TWEAK) is a growth factor for bipotent liver progenitors that express its receptor, fibroblast growth factor-inducible 14 (Fn14), a TNF receptor superfamily member. Accumulation of Fn14+ progenitors occurs in severe acute alcoholic steatohepatitis (ASH) and correlates with acute mortality. In patients with severe ASH, inhibition of TNF-α increases acute mortality. The aim of this study was to determine whether deletion of Fn14 improves the outcome of liver injury in alcohol-consuming mice. Wild-type (WT) and Fn14 knockout (KO) mice were fed control high-fat Lieber deCarli diet or high-fat Lieber deCarli diet with 2% alcohol (ETOH) and...

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