bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuropeptide Y induces fasted pattern of duodenal motility via Y2 receptors in conscious fed rats
Authors: Fujimiya Mineko , Itoh Etsuro , Kihara Naoki , Yamamoto Ikuo , Fujimura Masaki , Inui Akio
Published: December 2017

Neuropeptide Y (NPY), a 36-amino acid peptide abundantly expressed in the brain, has been implicated in the regulation of feeding and visceral functions. The present study was designed to investigate whether or not NPY specifically regulates duodenal motility. The manometric method was used to measure duodenal motility in conscious, freely moving rats. The rat duodenum showed phasic contractions mimicking the migrating motor complex in the fasted state that were replaced by irregular contractions after the ingestion of food. NPY powerfully affected the contractile activity after intracerebroventricular (icv) administration, changing fed (postprandial) patterns into phasic contractions characterized as fasted (interdigestive) patterns. This effect was mediated via receptors with pharmacological profiles similar to rat Y2and Y4 receptors, although neither Y1 nor Y5 agonists had any effects on motility despite potent feeding-stimulatory effects. Immunoneutralization with anti-NPY antiserum administered icv abolished fasted patterns and induced fed-like motor activities. An icv dose of peptide YY produced a different effect from NPY, with increase in the motor activities of both fed and fasted patterns. These results indicate that fasted and fed motor activities are regulated processes and that NPY induces fasted activity through Y2, and possibly Y4, receptors, which may represent an integrated mechanism linked to the onset of feeding behavior.
Role of ubiquitin in proteasomal degradation of mutant α1-antitrypsin Z in the endoplasmic reticulum
Authors: Teckman Jeffrey H. , Gilmore Reid , Perlmutter David H.
Published: December 2017

A delay in intracellular degradation of the mutant α1-antitrypsin (α1AT)Z molecule is associated with greater retention within the endoplasmic reticulum (ER) and susceptibility to liver disease in a subgroup of patients with α1AT deficiency. Recent studies have shown that α1ATZ is ordinarily degraded in the ER by a mechanism that involves the proteasome, as demonstrated in intact cells using human fibroblast cell lines engineered for expression of α1ATZ and in a cell-free microsomal translocation assay system programmed with purified α1ATZ mRNA. To determine whether the ubiquitin system is required for proteasomal degradation of α1ATZ and whether specific components of the ubiquitin system can be implicated, we have now used two approaches. First, we overexpressed a dominant-negative ubiquitin mutant (UbK48R-G76A) by transient transfection in the human fibroblast cell lines expressing α1ATZ. The results showed that there was marked, specific, and selective inhibition of α1ATZ degradation mediated by UbK48R-G76A, indicating that the ubiquitin system is at least in part involved in ER degradation of α1ATZ. Second, we subjected reticulocyte lysate to DE52 chromatography and tested the resulting well-characterized fractions in the cell-free system. The results showed that there were both ubiquitin-dependent and -independent proteasomal mechanisms for degradation of α1ATZ and that the ubiquitin-conjugating enzyme E2-F1 may play a role in the ubiquitin-dependent proteasomal mechanism.
Gene expression of activin, activin receptors, and follistatin in intestinal epithelial cells
Authors: Sonoyama Kei , Rutatip Suriya , Kasai Takanori
Published: December 2017

Gene expression of activin, activin receptors, and follistatin was investigated in vivo and in vitro using semiquantitative RT-PCR in intestinal epithelial cells. Rat jejunum and the intestinal epithelial cell line IEC-6 expressed mRNA encoding the βA-subunit of activin, α-subunit of inhibin, activin receptors IB and IIA, and follistatin. An epithelial cell isolation study focused along the crypt-villus axis in rat jejunum showed that βA mRNA levels were eight- to tenfold higher in villus cells than in crypt cells. Immunohistochemistry revealed the expression of activin A in upper villus cells. The human intestinal cell line Caco-2 was used as a differentiation model of enterocytes. Four- to fivefold induction of βA mRNA was observed in postconfluent Caco-2 cells grown on filter but not in those cells grown on plastic. In contrast, follistatin mRNA was seen to be reduced after reaching confluence. Exogenous activin A dose-dependently suppressed the proliferation and stimulated the expression of apolipoprotein A-IV gene, a differentiation marker, in IEC-6 cells. These results suggest that the activin system is involved in the regulation of such cellular functions as proliferation and differentiation in intestinal epithelial cells.
Glucocorticoids and dietary iron regulate postnatal intestinal heavy and light ferritin expression in rats
Authors: Yeh Kwo-Yih , Yeh Mary , Glass Jonathan
Published: December 2017

To cope with increasing dietary iron exposure, the intestinal epithelium of weaning rats must control intracellular labile iron pools. Intestinal expression of heavy (H) and light (L) ferritin subunits during early weaning and after cortisone administration and/or iron feeding was investigated. Changes in H and L ferritin gene expression were determined by nuclear runoff transcriptional assay, Northern blot analysis, and metabolic labeling of protein synthesis. H ferritin mRNA levels did not change between days 12 and 15, doubled on day 18, and tripled on day 24. L ferritin mRNA was reduced by 50% on days 18 and 24. The protein level of the H and L subunits paralleled the change in mRNAs. Cortisone treatment on day 12 induced a precocious increase of H and decrease of L mRNA expression on day 15. Nuclear runoff assays showed that cortisone did not change H and reduced L ferritin gene transcription. The increased level of H mRNA by cortisone was not translated, unless the rats were fed an iron-fortified diet, which reduced iron regulatory protein activity and stimulated a three- to sixfold increase of ferritin synthesis. Thus changes in intestinal H and L ferritin expression in weaning rats are modulated by glucocorticoids and iron; the former stabilizes H mRNA and suppresses L ferritin gene transcription, and the latter derepresses translation of ferritin mRNA.
Inflammation-induced impairment of enteric nerve function in nematode-infected mice is macrophage dependent
Authors: Galeazzi Francesca , Haapala Eric M. , van Rooijen Nico , Vallance Bruce A. , Collins Stephen M.
Published: December 2017

Trichinella spiralis infection in rodents is associated with suppression of ACh release from myenteric plexus that can be mimicked by macrophage-derived cytokines. We verified the presence of a macrophage infiltrate in the intestine during T. spiralis infection and determined the extent to which this cell type is responsible for the neural changes. C57BL/6 mice were infected with 375 T. spiralis larvae by gavage, and the presence of macrophages (F4/80 positive) in the jejunum was determined immunohistochemically. In another experiment, infected mice were treated intravenously with liposomes containing dichloromethylene diphosphonate (clodronate, Cl2MDP), which causes apoptosis of macrophages, and killed at postinfection day 6, and jejunal tissues were evaluated for the presence of F4/80-positive cells and for [3H]ACh release from the myenteric plexus. Infection caused an infiltration of F4/80-positive cells into the intestinal mucosa, muscle layers, and myenteric plexus region and a significant suppression of ACh release (50%). Depletion of F4/80-positive macrophages using Cl2MDP-containing liposomes prevented the suppression in [3H]ACh release, identifying macrophages as the cell type involved in the functional impairment of enteric cholinergic nerves.
Syncollin is differentially expressed in rat proximal small intestine and regulated by feeding behavior
Authors: Tan Sandra , Hooi Shing C.
Published: December 2017

Gradients of gene expression are maintained along the proximal-distal axis of the mammalian small intestine despite a continuously regenerating epithelium. To study the molecular mechanisms responsible for this phenomenon, we utilized a subtractive hybridization strategy to isolate genes differentially expressed in the duodenum but not ileum. We isolated and sequenced 15 clones. The clones were fragments of genes encoding lipases, proteases, and an esterase. A novel clone was characterized and subsequently shown to encode syncollin, a secretory granule protein that binds to syntaxin in a calcium-sensitive manner. RT-PCR and S1 nuclease protection assay were used to clarify the 5′-end of syncollin. Syncollin was expressed in the rat pancreas, spleen, duodenum, and colon. In situ hybridization localized syncollin expression in the pancreas to acinar cells and in the duodenum to villus epithelial cells.
Relationships between spatial patterns of colonic pressure and individual movements of content
Authors: Cook Ian J. , Furukawa Yoshiyuki , Panagopoulos Voula , Collins Peter J. , Dent John
Published: December 2017

The aim of this study was to examine the relationship between colonic pressure waves and movement of content. In 11 healthy subjects, pressures were recorded at 10-cm intervals from cecum to rectum for 32 h. In six subjects, transit was simultaneously measured for 8 h after direct cecal instillation of 1.5 mCi of 99mTc sulfur colloid. Thirty-two percent of isotope movements were related to nonpropagating activity and twenty-eight percent to propagating sequences. The extent of isotope movement related to propagating sequences (25.1 ± 2.1 cm) was greater than that due to nonpropagating activity (12.8 ± 0.7 cm; P = 0.0001). Propagating sequences originated significantly more frequently ( P = 0.004) and propagated further ( P = 0.0006) in the proximal compared with the distal colon. Only 36% of propagating sequences were propulsive of content, and compared with nonpropulsive sequences, these propagated further (41 ± 6 vs. 27 ± 2 cm; P < 0.05) and had a higher probability of originating proximally ( P = 0.0003), a higher pressure wave amplitude (50 ± 5 vs. 34 ± 4 mmHg; P = 0.0001), and slower velocity (2.2 ± 0.3 vs. 3.6 ± 0.47 cm/s; P = 0.02). We conclude that most movements of colonic content are related to pressure waves. There is marked regional variation in the prevalence, velocity, and extent of propagation of propagating pressure wave sequences, which are an important mechanism for transporting content over long distances. The effectiveness of transport by a propagating sequence is influenced by its site of origin, amplitude, and velocity.
Mice overexpressing progastrin are predisposed for developing aberrant colonic crypt foci in response to AOM
Authors: Singh Pomila , Velasco Marco , Given Randall , Wargovich Michael , Varro Andrea , Wang Timothy C.
Published: December 2017

Recent studies show that nonamidated gastrins (Gly-gastrin and progastrin) stimulate colonic proliferation. However, the role of nonamidated vs. amidated gastrins in colon carcinogenesis has not been defined. We measured intermediate markers of carcinogenesis in transgenic mice overexpressing either progastrin (hGAS) or amidated gastrin (INS-GAS) in response to azoxymethane (AOM). The hGAS mice showed significantly higher numbers of aberrant crypt foci (140–200% increase) compared with that in wild-type (WT) and INS-GAS mice ( P < 0.05) after AOM treatment. The bromodeoxyuridine-labeling index of colonic crypts also was significantly elevated in hGAS mice vs. that in WT and INS-GAS mice. The results therefore provide evidence for a mitogenic and cocarcinogenic role of nonamidated gastrins (progastrin), which is apparently not shared by the amidated gastrins. Although nonamidated gastrins are now believed to mediate mitogenic effects via novel receptors, amidated gastrins mediate biological effects via different receptor subtypes, which may explain the difference in the cocarcinogenic potential of nonamidated vs. amidated gastrins. In conclusion, our results provide strong support for a cocarcinogenic role for nonamidated gastrins in colon carcinogenesis.
Mechanisms of Mg2+transport in cultured ruminal epithelial cells
Authors: Schweigel Monika , Vormann Jürgen , Martens Holger
Published: December 2017

Net Mg2+absorption from the rumen is mainly mediated by a transcellular pathway, with the greater part (62%) being electrically silent. To investigate this component of Mg2+transport, experiments were performed with isolated ruminal epithelial cells (REC). Using the fluorescent indicators mag-fura 2, sodium-binding benzofuran isophthalate, and 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, we measured the intracellular free Mg2+concentration ([Mg2+]i), the intracellular Na+concentration ([Na+]i), and the intracellular pH (pHi) of REC under basal conditions, after stimulation with butyrate and [Formula: see text], and after changing the transmembrane chemical gradients for Mg2+, H+, and Na+. REC had a mean resting pHiof 6.83 ± 0.1, [Mg2+]iwas 0.56 ± 0.14 mM, and [Na+]iwas 18.95 ± 3.9 mM. Exposure to both [Formula: see text] and[Formula: see text]/butyrate led to a stimulation of Mg2+influx that amounted to 27.7 ± 5 and 29 ± 10.6 μM/min, respectively, compared with 15 ± 1 μM/min in control solution. The increase of [Mg2+]iwas dependent on extracellular Mg2+concentration ([Mg2+]e). Regulation of pHihas been demonstrated to be Na+dependent and is performed, for the most part, by a Na+/H+exchanger. The recovery of pHiwas fully blocked in nominally Na+-free media, even if [Mg2+]ewas stepwise increased from 0 to 7.5 mM. However, an increase of [Mg2+]iwas observed after reversing the transmembrane Na+gradient. This rise in [Mg2+]iwas pH independent, K+insensitive, dependent on [Mg2+]e, imipramine and quinidine sensitive, and accompanied by a decrease of [Na+]i. The results are consistent with the existence of a Na+/Mg2+exchanger in the cell membrane of REC. The coupling between butyrate, CO2/[Formula: see text] and Mg2+transport may be mediated by another mechanism, perhaps by cotransport of Mg2+and[Formula: see text].
Hepatic glutamine transporter activation in burn injury: role of amino acids and phosphatidylinositol-3-kinase
Authors: Pawlik Timothy M. , Lohmann Rüdiger , Souba Wiley W. , Bode Barrie P.
Published: December 2017

Burn injury elicits a marked, sustained hypermetabolic state in patients characterized by accelerated hepatic amino acid metabolism and negative nitrogen balance. The transport of glutamine, a key substrate in gluconeogenesis and ureagenesis, was examined in hepatocytes isolated from the livers of rats after a 20% total burn surface area full-thickness scald injury. A latent and profound two- to threefold increase in glutamine transporter system N activity was first observed after 48 h in hepatocytes from injured rats compared with controls, persisted for 9 days, and waned toward control values after 18 days, corresponding with convalescence. Further studies showed that the profound increase was fully attributable to rapid posttranslational transporter activation by amino acid-induced cell swelling and that this form of regulation may be elicited in part by glucagon. The phosphatidylinositol-3-kinase (PI3K) inhibitors wortmannin and LY-294002 each significantly attenuated transporter stimulation by amino acids. The data suggest that PI3K-dependent system N activation by amino acids may play an important role in fueling accelerated hepatic nitrogen metabolism after burn injury.
Defective cholinergic Cl− secretion and detection of K+ secretion in rectal biopsies from cystic fibrosis patients
Authors: Mall M. , Wissner A. , Seydewitz H. H. , Kuehr J. , Brandis M. , Greger R. , Kunzelmann K.
Published: December 2017

Rectal biopsies from cystic fibrosis (CF) patients show defective cAMP-activated Cl− secretion and an inverse response of the short-circuit current ( I sc) toward stimulation with carbachol (CCh). Alternative Cl− channels are found in airway epithelia and have been attributed to residual Cl− secretion in CF colon. The aim of the present study was to investigate ion conductances causing reversed I sc upon cholinergic stimulation. Furthermore, the putative role of an alternative Ca2+-dependent Cl− conductance in human distal colon was examined. Cholinergic ion secretion was assessed in the absence and presence of cAMP-dependent stimulation. Transepithelial voltage and I sc were measured in rectal biopsies from non-CF and CF individuals by means of a perfused micro-Ussing chamber. Under baseline conditions, CCh induced a positive I sc in CF rectal biopsies but caused a negative I sc in non-CF subjects. The CCh-induced negative I sc in non-CF biopsies was gradually reversed to a positive response by incubating the biopsies in indomethacin. The positive I sc was significantly enhanced in CF and was caused by activation of a luminal K+ conductance, as shown by the use of the K+ channel blockers Ba2+ and tetraethylammonium. Moreover, a cAMP-dependent luminal K+conductance was detected in CF individuals. We conclude that the cystic fibrosis transmembrane conductance regulator is the predominant Cl− channel in human distal colon. Unlike human airways, no evidence was found for an alternative Cl−conductance in native tissues from CF patients. Furthermore, we demonstrated that both Ca2+- and cAMP-dependent K+ secretion are present in human distal colon, which are unmasked in rectal biopsies from CF patients.
Effects of enteral glutamine on gut mucosal protein synthesis in healthy humans receiving glucocorticoids
Authors: Bouteloup-Demange Corinne , Claeyssens Sophie , Maillot Celine , Lavoinne Alain , Lerebours Eric , Dechelotte Pierre
Published: December 2017

In hypercatabolic patients, the beneficial effects of glutamine on gut mucosa could be partly due to a stimulation of protein synthesis. The fractional synthesis rate (FSR) of gut mucosal protein was measured in four groups of healthy volunteers treated with glucocorticoids for 2 days. Two groups were studied in the postabsorptive state while receiving glutamine or a nitrogen equivalent (control) and two groups in the fed state with or without glutamine, using a 5-h intravenous infusion of [13C]leucine, [2H5]phenylalanine, and cortisone. After nutrient and tracer infusion, duodenal biopsies were taken. In the postabsorptive state, FSR of gut mucosal protein were 87 and 76%/day in the control group and 130% ( P = 0.058 vs. control) and 104% ( P = 0.17 vs. control)/day in the glutamine group, with leucine and phenylalanine as tracers, respectively. During feeding, FSR did not increase and no significant difference was observed between glutamine and control groups. Overall, FSR of the four groups were two- to threefold higher than those obtained previously in healthy humans, suggesting that glucocorticoids may increase gut mucosal protein synthesis. However, in this situation, a moderate enteral glutamine supply failed to demonstrate a significant effect on gut mucosal protein synthesis in the postabsorptive state and during feeding.
Cytokine and endothelial cell adhesion molecule expression in interleukin-10-deficient mice
Authors: Kawachi Shigeyuki , Jennings Stephen , Panes Julian , Cockrell Adam , Laroux F. Stephen , Gray Laura , Perry Michael , van der Heyde Henry , Balish Edward , Granger D. Neil , Specian Robert A. , Grisham Matthew B.
Published: December 2017

The objectives of this study were to quantify cytokine mRNA levels and endothelial cell adhesion molecule message and protein expression in healthy wild-type and interleukin-10-deficient (IL-10−/−) mice that develop spontaneous and chronic colitis. We found that colonic message levels of IL-1, IL-6, tumor necrosis factor-α, interferon-γ, lymphotoxin-β, and transforming growth factor-β were elevated in colitic mice 10- to 35-fold compared with their healthy wild-type controls. In addition, colonic message levels of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) were found to be increased 10-, 5-, and 23-fold, respectively, in colitic IL-10−/−mice compared with their wild-type controls. Immunoradiolabeling as well as immunohistochemistry revealed large and significant increases in vascular surface expression of colonic ICAM-1, VCAM-1, and MAdCAM-1 in the mucosa as well as the submucosa of the colons of colitic mice. These data are consistent with the hypothesis that deletion of IL-10 results in the sustained production of proinflammatory cytokines, leading to the upregulation of adhesion molecules and infiltration of mononuclear and polymorphonuclear leukocytes into the cecal and colonic interstitium.
Luminal dietary protein, not amino acids, induces pancreatic protease via CCK in pancreaticobiliary-diverted rats
Authors: Hara Hiroshi , Ohyama Sumika , Hira Tohru
Published: December 2017

We determined whether pancreatic adaptation to a high-protein diet depends on ingested protein in the intestinal lumen and whether such adaptation depends on a CCK or capsaicin-sensitive vagal afferent pathway in pancreaticobiliary-diverted (PBD) rats. Feeding a high-casein (60%) diet but not a high-amino acid diet to PBD rats increased pancreatic trypsin and chymotrypsin activities compared with those after feeding a 25% casein diet. In contrast, feeding both the high-nitrogen diets induced pancreatic hypertrophy in PBD rats. These pancreatic changes by the diets were abolished by treatment with devazepide, a CCK-A receptor antagonist. Protease zymogen mRNA abundance in the PBD rat was not increased by feeding the high-casein diet and was decreased by devazepide. Perivagal capsaicin treatment did not influence the values of any pancreatic variables in PBD rats fed the normal or high-casein diet. We concluded that luminal protein or peptides were responsible for the bile pancreatic juice-independent induction of pancreatic proteases on feeding a high-protein diet. The induction was found to be dependent on the direct action of CCK on the pancreas. Pancreatic growth induced by high-protein feeding in PBD rats may depend at least partly on absorbed amino acids.
Human Caco-2 motility redistributes FAK and paxillin and activates p38 MAPK in a matrix-dependent manner
Authors: Yu Cheng Fang , Sanders Matthew A. , Basson Marc D.
Published: December 2017

The signals involved in restitution during mucosal healing are poorly understood. We compared focal adhesion kinase (FAK) and paxillin protein and phosphorylation, extracellular signal-regulated kinase (ERK) 1, ERK2, and p38 activation, as well as FAK and paxillin organization in static and migrating human intestinal Caco-2 cells on matrix proteins and anionically derivatized polystyrene dishes (tissue culture plastic). We also studied effects of FAK, ERK, and p38 blockade in a monolayer-wounding model. Compared with static cells, cells migrating across matrix proteins matrix-dependently decreased membrane/cytoskeletal FAK and paxillin and cytosolic FAK. Tyrosine phosphorylated FAK and paxillin changed proportionately to FAK and paxillin protein. Conversely, cells migrating on plastic increased FAK and paxillin protein and phosphorylation. Migration matrix-dependently activated p38 and inactivated ERK1 and ERK2. Total p38, ERK1, and ERK2 did not change. Caco-2 motility was inhibited by transfection of FRNK (the COOH-terminal region of FAK) and PD-98059, a mitogen-activated protein kinase-ERK kinase inhibitor, but not by SB-203580, a p38 inhibitor, suggesting that FAK and ERK modulate Caco-2 migration. In contrast to adhesion-induced phosphorylation, matrix may regulate motile intestinal epithelial cells by altering amounts and distribution of focal adhesion plaque proteins available for phosphorylation as well as by p38 activation and ERK inactivation. Motility across plastic differs from migration across matrix.
Inhibition of human gastric H+-K+-ATPase α-subunit gene expression byHelicobacter pylori
Authors: Göõz Monika , Hammond Charles E. , Larsen Kellie , Mukhin Yurii V. , Smolka Adam J.
Published: December 2017

Clinical studies and in vitro data from isolated parietal cells suggest that acute Helicobacter pylori infection inhibits acid secretion. Gastric acidification is mediated by H+-K+-ATPase, an integral protein of parietal cell apical membranes. To test the hypothesis that H. pyloridownregulates H+-K+-ATPase α-subunit (HKα) gene expression and to identify potential intracellular signaling pathways mediating such regulation, we transfected human gastric adenocarcinoma (AGS) cells with human and rat HKα 5′-flanking DNA fused to a luciferase reporter plasmid. Histamine caused dose-dependent, cimetidine-sensitive (10−4M) increases in cAMP, free intracellular Ca2+, and HKα promoter activation in AGS cells. H. pylori infection of transfected AGS cells dose dependently inhibited basal and histamine-stimulated HKα promoter activity by 80% and 66%, respectively. H. pylori dose dependently inhibited phorbol myristate acetate-induced (10−7M) and staurosporine- (10−7M) and calphostin C-sensitive (5 × 10−8M) activation of HKα promoter. Also, H. pylori inhibited epidermal growth factor (EGF) (10−8M), genistein-sensitive (5 × 10−5M) activation of HKα promoter, reducing activity to 60% of basal level. These data suggest that H. pyloriinhibits HKα gene expression via intracellular pathways involving protein kinases A and C and protein tyrosine kinase, AGS cells have functional histamine H2and EGF receptors, and transiently transfected AGS cells are a useful model for studying regulation of HKα gene expression.
Agonist-induced cytoplasmic volume changes in cultured rabbit parietal cells
Authors: Sonnentag Thorsten , Siegel Wolf-Kristian , Bachmann Oliver , Rossmann Heidi , Mack Andreas , Wagner Hans-Joachim , Gregor Michael , Seidler Ursula
Published: December 2017

Concomitant Na+/H+and Cl−/HCO3−exchange activation occurs during stimulation of acid secretion in cultured rabbit parietal cells, possibly related to a necessity for volume regulation during the secretory process. We investigated whether cytoplasmic volume changes occur during secretagogue stimulation of cultured rabbit parietal cells. Cells were loaded with the fluorescent dye calcein, and the calcein concentration within a defined cytoplasmic volume was recorded by confocal microscopy. Forskolin at 10−5M, carbachol at 10−4M, and hyperosmolarity (400 mosmol) resulted in a rapid increase in the cytoplasmic dye concentration by 21 ± 6, 9 ± 4, and 23 ± 5%, respectively, indicative of cell shrinkage, followed by recovery to baseline within several minutes, indicative of regulatory volume increase (RVI). Depolarization by 5 mM barium resulted in a decrease of the cytoplasmic dye concentration by 10 ± 2%, indicative of cell swelling, with recovery within 15 min, and completely prevented forskolin- or carbachol-induced cytoplasmic shrinkage. Na+/H+exchange inhibitors slightly reduced the initial cell shrinkage and significantly slowed the RVI, whereas 100 μM bumetanide had no significant effect on either parameter. We conclude that acid secretagoguges induce a rapid loss of parietal cell cytoplasmic volume, followed by RVI, which is predominantly mediated by Na+/H+and Cl−/HCO3−exchange.
Colon water transport in transgenic mice lacking aquaporin-4 water channels
Authors: Wang Kasper S. , Ma Tonghui , Filiz Ferda , Verkman A. S. , Bastidas J. Augusto
Published: December 2017

Transgenic null mice were used to test the hypothesis that water channel aquaporin-4 (AQP4) is involved in colon water transport and fecal dehydration. AQP4 was immunolocalized to the basolateral membrane of colonic surface epithelium of wild-type (+/+) mice and was absent in AQP4 null (−/−) mice. The transepithelial osmotic water permeability coefficient ( Pf) of in vivo perfused colon of +/+ mice, measured using the volume marker14C-labeled polyethylene glycol, was 0.016 ± 0.002 cm/s. Pfof proximal colon was greater than that of distal colon (0.020 ± 0.004 vs. 0.009 ± 0.003 cm/s, P < 0.01). Pfwas significantly lower in −/− mice when measured in full-length colon (0.009 ± 0.002 cm/s, P< 0.05) and proximal colon (0.013 ± 0.002 cm/s, P< 0.05) but not in distal colon. There was no difference in water content of cecal stool from +/+ vs. −/− mice (0.80 ± 0.01 vs. 0.81 ± 0.01), but there was a slightly higher water content in defecated stool from −/− mice (0.68 ± 0.01 vs. 0.65 ± 0.01, P < 0.05). Despite the differences in water permeability with AQP4 deletion, theophylline-induced secretion was not impaired (50 ± 9 vs. 51 ± 8 μl · min−1· g−1). These results provide evidence that transcellular water transport through AQP4 water channels in colonic epithelium facilitates transepithelial osmotic water permeability but has little or no effect on colonic fluid secretion or fecal dehydration.
PRL-1 PTPase expression is developmentally regulated with tissue-specific patterns in epithelial tissues
Authors: Kong Weihong , Swain Gary P. , Li Shiuxing , Diamond Robert H.
Published: December 2017

The mechanisms controlling tyrosine phosphorylation of cellular proteins are important in the regulation of many cellular processes, including development and differentiation. Protein tyrosine phosphatases (PTPases) may be as important as protein tyrosine kinases (PTKs) in these processes. PRL-1 is a distinct PTPase originally identified as an immediate-early gene in liver regeneration whose expression is associated with growth in some tissues but with differentiation in others. We now demonstrate that the PRL-1 protein is expressed during development in a number of digestive epithelial tissues. It is expressed at variable time points in the developing intestine, but its expression is limited to the developing villus enterocytes. In the gastric epithelium, PRL-1 expression in the adult is restricted to zymogen cells. PRL-1 is also expressed in the developing liver and esophagus and in the epithelia of the kidney and lung. In each of these contexts, the expression of PRL-1 is associated with terminal differentiation, suggesting that it may play a role in this important developmental process.
Role of cyclooxygenase-2 inHelicobacter pylori- induced gastritis in Mongolian gerbils
Authors: Takahashi Satoru , Fujita Takuya , Yamamoto Akira
Published: December 2017

Cyclooxygenase (COX)-2 expression is induced in the gastric mucosa of Helicobacter pylori-infected patients, but its role remains unclear. We examined the effects of NS-398 and indomethacin on gastric pathology in H. pylori-infected Mongolian gerbils. COX-1 was detected in both normal and H. pylori-infected mucosa, whereas COX-2 was expressed only in the infected mucosa. PGE2production was elevated by H. pylori infection, and the increased production was reduced by NS-398, which did not affect PGE2production in normal mucosa. Indomethacin inhibited PGE2production in both normal and infected mucosa. Hemorrhagic erosions, neutrophil infiltration, lymphoid follicles, and epithelium damage were induced by H. pylori infection. NS-398 and indomethacin aggravated these pathological changes but did not increase viable H. pylori number. H. pylori-increased production of neutrophil chemokine and interferon-γ was potentiated by NS-398 and indomethacin. Neither NS-398 nor indomethacin caused any pathological changes or cytokine production in normal animals. These results indicate that COX-2 as well as COX-1 might play anti-inflammatory roles in H. pylori-induced gastritis.
Ileal short-chain fatty acids inhibit gastric motility by a humoral pathway
Authors: Cuche G. , Cuber J. C. , Malbert C. H.
Published: December 2017

The aim of this study was to evaluate the nervous and humoral pathways involved in short-chain fatty acid (SCFA)-induced ileal brake in conscious pigs. The role of extrinsic ileal innervation was evaluated after SCFA infusion in innervated and denervated Babkin's ileal loops, and gastric motility was measured with strain gauges. Peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) concentrations were evaluated in both situations. The possible involvement of absorbed SCFA was tested by using intravenous infusion of acetate. Ileal SCFA infusion in the intact terminal ileum decreased the amplitude of distal and terminal antral contractions (33 ± 1.2 vs. 49 ± 1.2% of the maximal amplitude recorded before infusion) and increased their frequency (1.5 ± 0.11 vs. 1.3 ± 0.10/min). Similar effects were observed during SCFA infusion in ileal innervated and denervated loops (amplitude, 35 ± 1.0 and 34 ± 0.8 vs. 47 ± 1.3 and 43 ± 1.2%; frequency, 1.4 ± 0.07 and 1.6 ± 0.06 vs. 1.1 ± 0.14 and 1.0 ± 0.12/min). Intravenous acetate did not modify the amplitude and frequency of antral contractions. PYY but not GLP-1 concentrations were increased during SCFA infusion in innervated and denervated loops. In conclusion, ileal SCFA inhibit distal gastric motility by a humoral pathway involving the release of an inhibiting factor, which is likely PYY.
Retention of mutant α1-antitrypsin Z in endoplasmic reticulum is associated with an autophagic response
Authors: Teckman Jeffrey H. , Perlmutter David H.
Published: December 2017

Although there is evidence for specific subcellular morphological alterations in response to accumulation of misfolded proteins in the endoplasmic reticulum (ER), it is not clear whether these morphological changes are stereotypical or if they depend on the specific misfolded protein retained. This issue may be particularly important for mutant secretory protein α1-antitrypsin (α1AT) Z because retention of this mutant protein in the ER can cause severe target organ injury, the chronic hepatitis/hepatocellular carcinoma associated with α1AT deficiency. Here we examined the morphological changes that occur in human fibroblasts engineered for expression and ER retention of mutant α1ATZ and in human liver from three α1AT-deficient patients. In addition to marked expansion and dilatation of ER, there was an intense autophagic response. Mutant α1ATZ molecules were detected in autophagosomes by immune electron microscopy, and intracellular degradation of α1ATZ was partially reduced by chemical inhibitors of autophagy. In contrast to mutant CFTRΔF508, expression of mutant α1ATZ in heterologous cells did not result in the formation of aggresomes. These results show that ER retention of mutant α1ATZ is associated with a marked autophagic response and raise the possibility that autophagy represents a mechanism by which liver of α1AT-deficient patients attempts to protect itself from injury and carcinogenesis.
Bioavailability of the flavanone naringenin and its glycosides in rats
Authors: Felgines Catherine , Texier Odile , Morand Christine , Manach Claudine , Scalbert Augustin , Régerat Françoise , Rémésy Christian
Published: December 2017

Naringenin, the predominant flavanone in grapefruit, mainly occurs as glycosides such as naringenin-7- rhamnoglucoside or naringenin-7-glucoside. This study compared kinetics of absorption of naringenin and its glycosides in rats either after a single flavanone-containing meal or after adaptation to a diet for 14 days. Regardless of the diet, circulating metabolites were glucurono- and sulfoconjugated derivatives of naringenin. The kinetics of absorption of naringenin and naringenin-7-glucoside were similar, whereas naringenin-7-rhamnoglucoside exhibited a delay in its intestinal absorption, resulting in decreased bioavailability. After naringenin-7-glucoside feeding, no glucoside was found in the cecum. However, after feeding naringenin-7-rhamnoglucoside, some naringenin-7-rhamnoglucoside accumulated in cecum before being hydrolyzed by intestinal microflora. Adaptation to flavanone diets did not induce accumulation of plasma naringenin. Moreover, flavanone cecal content markedly decreased after adaptation, and almost no naringenin-7-rhamnoglucoside was recovered after naringenin-7-rhamnoglucoside feeding, suggesting that an adaptation of cecal microflora had occurred. Overall, these data indicate that flavanones are efficiently absorbed after feeding to rats and that their bioavailability is related to their glycosidic moiety.
Intraluminal acid and gastric mucosal integrity: the importance of blood-borne bicarbonate
Authors: Synnerstad Ingrid , Johansson Mia , Nylander Olof , Holm Lena
Published: December 2017

The acid-secreting gastric mucosa resists intraluminal acid better than the nonsecreting. Here we investigated pH at the epithelial cell surface, mucosal permeability, and blood flow during intraluminal administration of acid (100 mM) in acid-stimulated and nonstimulated gastric corpus mucosae. Surface pH (H+-selective microelectrodes), permeability (clearance of51Cr-EDTA), and mucosal blood flow (laser-Doppler flowmetry) were studied in Inactin-anesthetized rats. Acid secretion was stimulated with pentagastrin (40 μg · kg−1· h−1) or impromidine (500 μg · kg−1· h−1), or HCO3−(5 mmol · kg−1· h−1) given intravenously. Surface pH was only slightly reduced by intraluminal acid in acid secretion-stimulated or HCO3−-treated rats but was substantially lowered in nonstimulated rats. Clearance increased threefold and blood flow increased by ≈75% in nonstimulated rats. During stimulated acid secretion or intravenous infusion of HCO3−, clearance was unchanged and blood flow increased by only ≈30% during intraluminal acid. Increased epithelial transport of HCO3−buffering the mucus gel is most probably the explanation for the acid-secreting mucosa being less vulnerable to intraluminal acid than the nonsecreting.
Role of sodium/hydrogen exchanger isoform NHE3 in fluid secretion and absorption in mouse and rat cholangiocytes
Authors: Mennone Albert , Biemesderfer Daniel , Negoianu Daniel , Yang Chao-Ling , Abbiati Thecla , Schultheis Patrick J. , Shull Gary E. , Aronson Peter S. , Boyer James L.
Published: December 2017

Na+/H+exchanger (NHE) isoforms play important roles in intracellular pH regulation and in fluid absorption. The isoform NHE3 has been localized to apical surfaces of epithelia and in some tissues may facilitate the absorption of NaCl. To determine whether the apical isoform NHE3 is present in cholangiocytes and to examine whether it has a functional role in cholangiocyte fluid secretion and absorption, immunocytochemical studies were performed in rat liver with NHE3 antibodies and functional studies were obtained in isolated bile duct units from wild-type and NHE3 (−/−) mice after stimulation with forskolin, using videomicroscopic techniques. Our results indicate that NHE3 protein is present on the apical membranes of rat cholangiocytes and on the canalicular membrane of hepatocytes. Western blots also detect NHE3 protein in rat cholangiocytes and isolated canalicular membranes. After stimulation with forskolin, duct units from NHE3 (−/−) mice fail to absorb the secreted fluid from the cholangiocyte lumen compared with control animals. Similar findings were observed in isolated bile duct units from wild-type mice and rats in the presence of the Na+/H+exchanger inhibitor 5-( N-ethyl- N-isopropyl)-amiloride. In contrast, we could not demonstrate absorption of fluid from the canalicular lumen of mouse or rat hepatocyte couplets after stimulation of secretion with forskolin. These findings indicate that NHE3 is located on the apical membrane of rat cholangiocytes and that this NHE isoform can function to absorb fluid from the lumens of isolated rat and mouse cholangiocyte preparations.
Cerebral cortical representation of reflexive and volitional swallowing in humans
Authors: Kern Mark K. , Jaradeh Safwan , Arndorfer Ronald C. , Shaker Reza
Published: December 2017

The purpose of this study was to compare cerebral cortical representation of experimentally induced reflexive swallow with that of volitional swallow. Eight asymptomatic adults (24–27 yr) were studied by a single-trial functional magnetic resonance imaging technique. Reflexive swallowing showed bilateral activity concentrated to the primary sensory/motor regions. Volitional swallowing was represented bilaterally in the insula, prefrontal, cingulate, and parietooccipital regions in addition to the primary sensory/motor cortex. Intrasubject comparison showed that the total volume of activity during volitional swallowing was significantly larger than that activated during reflexive swallows in either hemisphere ( P < 0.001). For volitional swallowing, the primary sensory/motor region contained the largest and the insular region the smallest volumes of activation in both hemispheres, and the total activated volume in the right hemisphere was significantly larger compared with the left ( P < 0.05). Intersubject comparison showed significant variability in the volume of activity in each of the four volitional swallowing cortical regions. We conclude that reflexive swallow is represented in the primary sensory/motor cortex and that volitional swallow is represented in multiple regions, including the primary sensory/motor cortex, insular, prefrontal/cingulate gyrus, and cuneus and precuneus region. Non-sensory/motor regions activated during volitional swallow may represent swallow-related intent and planning and possibly urge.
Rat colon ornithine and arginine metabolism: coordinated effects after proliferative stimuli
Authors: Han Xiaoli , Kazarinoff Michael N. , Seiler Nikolaus , Stanley Bruce A.
Published: December 2017

Ornithine decarboxylase (ODC) catalyzes the first step in the polyamine biosynthetic pathway, a highly regulated pathway in which activity increases during rapid growth. Other enzymes also metabolize ornithine, and in hepatomas, rate of growth correlates with decreased activity of these other enzymes, which thus channels more ornithine to polyamine biosynthesis. Ornithine is produced from arginase cleavage of arginine, which also serves as the precursor for nitric oxide production. To study whether short-term coordination of ornithine and arginine metabolism exists in rat colon, ODC, ornithine aminotransferase (OAT), arginase, ornithine, arginine, and polyamine levels were measured after two stimuli (refeeding and/or deoxycholate exposure) known to synergistically induce ODC activity. Increased ODC activity was accompanied by increased putrescine levels, whereas OAT and arginase activity were reduced by either treatment, accompanied by an increase in both arginine and ornithine levels. These results indicate a rapid reciprocal change in ODC, OAT, and arginase activity in response to refeeding or deoxycholate. The accompanying increases in ornithine and arginine concentration are likely to contribute to increased flux through the polyamine and nitric oxide biosynthetic pathways in vivo.
Disordered central cardiovascular regulation in portal hypertensive and cirrhotic rats
Authors: Song Daisheng , Sharkey Keith A. , Breitman Deanne R. , Zhang Yikun , Lee Samuel S.
Published: December 2017

Portal hypertension due to either prehepatic portal hypertension or cirrhosis is associated with cardiovascular derangement. We aimed to delineate regulatory mechanisms in the brain stem cardiovascular nuclei in rat models of prehepatic portal hypertension and cirrhosis. Neuronal activation in the nucleus of the solitary tract (NTS) and ventrolateral medulla (VLM) were assessed by immunohistochemical staining for the immediate-early gene product Fos. In the same sections, catecholaminergic neurons were counted by tyrosine hydroxylase (TH) staining. Ninety minutes after hypotensive hemorrhage (or no volume challenge), the animals were killed for Fos and TH medullary staining. These protocols were repeated after capsaicin administration. The NTS of unchallenged sham-operated rats had scant Fos-positive cells (3.6 ± 0.4 cells/section), whereas hemorrhage significantly increased Fos staining (91.8 ± 14). In contrast, the unchallenged portal hypertensive and cirrhotic groups showed increased Fos staining (14.3 ± 5.8 and 32.8 ± 2.8, respectively), which hemorrhage did not alter significantly. The numbers of TH-positive cells were similar in the three unchallenged groups; double labeling revealed that ∼50% of TH-positive cells were activated by hemorrhage in the sham and cirrhotic rats but not the portal hypertensive rats. Similar patterns of Fos and TH staining were observed in the VLM. Capsaicin treatment not only significantly reduced the Fos-positive neuron numbers in portal hypertensive and cirrhotic rats but also attenuated hemorrhage-induced Fos and double-positive cells in both NTS and VLM. These results suggest that disordered trafficking in capsaicin-sensitive nerves and central dysregulation contribute to blunted cardiovascular responsiveness in cirrhosis and prehepatic portal hypertension.
Determinants of terminal mesenteric artery resistance during the first postnatal month
Authors: Nankervis Craig A. , Dunaway David J. , Nowicki Philip T.
Published: December 2017

Experiments were conducted to delineate the vascular effector systems that contribute to setting mesenteric vascular tone in swine during the first postnatal month. Terminal mesenteric arteries (TMA), which function as resistance vessels, were studied in vitro with a microvascular perfusion system allowing independent pressure and flow manipulation. When pressure was varied 0–100 mmHg in the absence of flow, TMA from 1-day-old animals demonstrated myogenic vasoconstriction, whereas TMA from 40-day-old animals did not. In 1- but not 40-day-old TMA, the endothelin A (ETA) receptor antagonist BQ-610 shifted the pressure-diameter curve upward, whereas the ETBreceptor antagonist BQ-788 and the l-arginine analog NG-monomethyl-l-arginine (l-NMMA) shifted the curve downward; in all instances, myogenic vasoconstriction was preserved. Flow eliminated myogenic vasoconstriction in 1-day-old TMA, i.e., diameter increased as a function of pressure. The effect of BQ-610 was lost under flow conditions; however, BQ-788 and N-acyl-l-Trp-3,5-bis-(trifluoromethyl) benzyl ester, an antagonist specific to the substance P neurokinin-1 (NK1) receptor, shifted the pressure-diameter curve downward in the presence of flow, whereas l-NMMA restored myogenic vasoconstriction. Adding flow had no effect on the pressure-diameter relationship in 40-day-old TMA. Other blocking agents, including prazosin, losartan, indomethacin, and charybdotoxin, had no effect on the pressure-diameter relationship in either age group under flow or no-flow conditions. Constitutive production of nitric oxide (NO) and endothelin-1 participates in setting resistance in 1-day-old TMA, and important stimulants to NO production include flow and activation of ETBand NK1receptors. In contrast, 40-day-old TMA act as passive conduits in which the elastic properties of the vessel are the primary determinant of diameter.
Targeted disruption of theNhe1gene fails to inhibit β1-adrenergic receptor-induced parotid gland hypertrophy
Authors: Melvin James E. , Nguyen Ha-Van , Nehrke Keith , Schreiner Claire M. , Ten Hagen Kelly G. , Scott William
Published: December 2017

Chronic β1-adrenergic receptor activation results in hypertrophy and hyperplasia of rodent salivary gland acinar cells. Na+/H+exchanger isoform 1 (NHE1) regulates cell volume and the induction of cell proliferation in many tissues. To investigate the relationship between NHE1 and the response of parotid glands to β1-adrenergic agonists, we examined by Northern blot analysis NHE1 expression in saline-treated mice and mice 30 min and 2, 6, and 24 h after isoproterenol injection. NHE1 transcripts increased ∼50% by 2 h, and a more than twofold increase was noted at 24 h. Isoproterenol did not acutely increase Na+/H+exchanger activity; however, exchanger activity was significantly elevated by 24 h. To test whether NHE1 activity is essential for inducing salivary gland hypertrophy in vivo, mice with targeted disruption of Nhe1 were treated with isoproterenol. Na+/H+exchanger activity was absent in acinar cells from Nhe1−/−mice, nevertheless, the lack of NHE1 failed to inhibit isoproterenol-induced hypertrophy. These data directly demonstrate that acinar cell hypertrophy induced by chronic β1-adrenergic receptor stimulation occurs independently of NHE1 activity.