bluuebunny/crossref_metadata_2025 huggingface dataset:
Butyrate upregulates stromelysin-1 production by intestinal mesenchymal cells
Authors: Pender Sylvia L. F. , Quinn Jessica J. , Sanderson Ian R. , MacDonald Thomas T.
Published: December 2017

Nutritional factors and resident bacteria participate in the pathogenesis of intestinal inflammation. However, the ways in which bacteria and complex diets might modulate matrix metalloproteinase (MMP) production are unknown. We hypothesized that butyrate might enhance production of MMPs, thus amplifying their response to signals in inflammatory conditions. Human mesenchymal cells were incubated with butyrate and then stimulated with cytokines. MMPs and inhibitors were studied by Western blotting and quantitative RT-PCR. Acetylation of histones was examined in Triton X acetic acid-urea gels by PAGE. We showed that butyrate selectively enhanced the protein production and mRNA expression of stromelysin-1 in tumor necrosis factor-α- or interleukin-1β-stimulated mesenchymal cells. Butyrate alone did not induce any change in MMP production or mRNA expression. It increased the acetylation of histones in mesenchymal cells. Furthermore, acetylation of histones (induced by trichostatin A) reproduced the effects of butyrate. Although butyrate is a major source of nutrient for the colonic epithelial cells, it modulates intestinal inflammation through the secretion of stromelysin-1 in stimulated stromal cells via the inhibition of histone deacetylase.
Role of cyclooxygenase-2 in modulating gastric acid secretion in the normal and inflamed rat stomach
Authors: Barnett Kirsty , Bell Cameron J. , McKnight Webb , Dicay Michael , Sharkey Keith A. , Wallace John L.
Published: December 2017

Nonsteroidal anti-inflammatory drugs elevate gastric acid secretion, possibly contributing to their ability to interfere with gastric ulcer healing. Inhibitors of cyclooxygenase-2 have been shown to delay experimental gastric ulcer healing. In the present study, we tested the hypothesis that cyclooxygenase-2-derived prostaglandins modulate gastric acid secretion. Studies were performed in normal rats and in rats with iodoacetamide-induced gastritis. Inflammation in the latter group was confirmed histologically and by a threefold increase in tissue levels of the granulocyte marker myeloperoxidase and was also associated with overexpression of cyclooxygenase-2 in the stomach. Basal acid secretion in both groups of rats was not affected by pretreatment with DuP-697, a selective inhibitor of cyclooxygenase-2. A nonselective cyclooxygenase inhibitor, indomethacin, had no effect on acid secretion in normal rats but caused a doubling of acid secretion in the rats with gastritis. DuP-697 had no effect on pentagastrin-induced secretion in either group of rats. Gastritis itself was associated with significantly increased pentagastrin-induced acid secretion, and this was further increased in rats pretreated with indomethacin. These results suggest that in a setting of gastric inflammation, prostaglandins derived from cyclooxygenase-1, not cyclooxygenase-2, exert inhibitory effects on acid secretion.
Thermal injury effects on intestinal crypt cell proliferation and death are cell position dependent
Authors: Varedi Maryam , Chinery Rebecca , Greeley George H. , Herndon David N. , Englander Ella W.
Published: December 2017

We examined the effects of thermal injury on intestinal epithelial cell proliferation and death. We recorded histologically identifiable mitotic and apoptotic crypt cells in relation to cell position after a 60% full thickness cutaneous thermal injury in the rat. The injury significantly reduced mitosis (0.53 ± 0.11 vs. 1.50 ± 0.70, P < 0.05) at cell positions 4–6, stem cells, 6 h after injury. A similar reduction in mitosis (1.13 ± 0.59 vs. 3.50 ± 0.80, P < 0.05) was observed at higher cell positions 7–9 12 h after injury, indicating a positional cell shift. In addition, a significant increase in the number of apoptotic bodies occurred at cell positions 7–9(2.32 ± 0.87 vs. 0.13 ± 0.22, P < 0.05) and 10–12 (2.2 ± 0.12 vs. 0.00, P< 0.05) 6 h after injury. Thermal injury-induced alterations in mitotic and apoptotic activities were transient since crypts recovered with a moderate increase in mitotic activity 24 h after injury. In control and thermal-injury rats 24 h after injury, crypt cell mitosis and apoptosis did not differ significantly. This demonstrates that cutaneous thermal injury causes a transient suppression of mitosis as well as induction of apoptosis in a cell position-dependent manner in the small intestinal crypt.
Isolation of functional polarized bile duct units from mouse liver
Authors: Cho Won Kyoo , Mennone Albert , Boyer James L.
Published: December 2017

The development of genetically altered murine animals has generated a need for in vitro systems in the mouse. We have now characterized a novel isolated bile duct unit (IBDU) preparation from the mouse to facilitate such studies. The mouse IBDU is isolated by portal perfusion of collagenase, blunt dissection, further enzymatic digestions, filtering through sized mesh, and culturing on Matrigel for 16–72 h. This mouse IBDU forms a central, enclosed lumen lined by polarized cytokeratin-19-positive cholangiocytes with numerous microvilli on the apical membrane. The IBDU responds to secretory stimuli, including secretin, vasoactive intestinal peptide, IBMX, and forskolin, resulting in expansion of the central lumen from secretion as quantified by videomicroscopy. The secretory response to secretin is dependent on Cl− and HCO3 − in the perfusate. These findings indicate that mouse IBDUs are intact, polarized, functional bile duct secretory units that permit quantitative measurements of fluid secretion from mouse bile duct epithelium for the first time. This method should facilitate studies of cholangiocyte secretion in genetically altered murine animal models.
Apical and basolateral EGF receptors regulate gastric mucosal paracellular permeability
Authors: Chen Monica C. , Goliger Jeffrey , Bunnett Nigel , Soll Andrew H.
Published: December 2017

Previous studies found that monolayers formed from canine oxyntic epithelial cells in primary culture displayed remarkable resistance to apical acidification and both mitogenic and migratory responses to epidermal growth factor (EGF) treatment. In our present studies, we found that EGF increased transepithelial resistance (TER) but not short-circuit current in these monolayers. Parallel effects of EGF on decreasing mannitol flux and increasing TER implicate direct regulation of paracellular permeability. EGF acting at either apical and basolateral receptors rapidly increased TER, but the apical response was sustained whereas the basolateral response was transient.125I-labeled EGF binding revealed specific apical binding, but receptor numbers were 25-fold lower than on the basolateral surface. Both apical and basolateral EGF activated tyrosine phosphorylation of EGF receptors (EGFR), β-catenin, and cellular substrate as evident on confocal microscopy. Although apical EGF activated a lesser degree of receptor autophosphorylation than basolateral EGF, phosphorylation of β-catenin was equally prominent with apical and basolateral receptor activation. Together, these findings indicate that functional apical and basolateral EGFR exist on primary canine gastric epithelial cells and that these receptors regulate paracellular permeability. The sustained effect of apical EGFR activation and prominent phosphorylation of β-catenin suggest that apical EGFR may play a key role in this regulation.
IV. Modulation of intestinal inflammation by stress: basic mechanisms and clinical relevance
Authors: Collins Stephen M.
Published: December 2017

The stress response in a healthy organism is generally viewed as a warning and thus a protective reaction to a threat. However, the response may be deleterious if it is linked to an inflammatory stimulus or if it proceeds an inflammatory event. Prior stress enhances the response to an inflammatory stimulus by a mechanism that is independent of the release of hypothalamic corticotropin-releasing factor (CRF) or arginine vasopressin. Putative mechanisms include an increase in intestinal permeability as well as the release of the proinflammatory neuropeptide substance P. Stress may also reactivate previous inflammation when applied in conjunction with a small luminal stimulus. This reactivation involves increased permeability and requires the presence of T lymphocytes. Inflammatory mediators activate hypothalamic pathways, and a negative feedback loop, mediated by CRF release, has been proposed because animals with impaired hypothalamic CRF responses are more susceptible to inflammatory stimuli. Together, these experimental observations provide insights into the expression of inflammatory disorders in humans, including inflammatory bowel disease and postinfective irritable bowel syndrome.
Catecholaminergic neurons in rat dorsal motor nucleus of vagus project selectively to gastric corpus
Authors: Guo Jinfeng J. , Browning Kirsteen N. , Rogers Richard C. , Travagli R. Alberto
Published: December 2017

Nitric oxide synthase-immunoreactive (NOS-IR) neurons in the rat caudal dorsal motor nucleus of the vagus (DMV) project selectively to the gastric fundus and may be involved in vagal reflexes controlling gastric distension. This study aimed to identify the gastric projections of tyrosine hydroxylase-immunoreactive (TH-IR) DMV neurons, whether such neurons colocalize NOS-IR, and if they are activated after esophageal distension. Gastric-projecting neurons were identified after injection of retrograde tracers into the muscle wall of the gastric fundus, corpus, or antrum/pylorus before removal and processing of the brain stems for TH- and NOS-IR. A significantly higher proportion of corpus- compared with fundus- and antrum/pylorus-projecting neurons were TH-IR (14% compared with 4% and 2%, respectively, P < 0.05). Colocalization of NOS- and TH-IR was never observed in gastric-projecting neurons. In rats tested for c-Fos activation after intermittent esophageal balloon distension, no colocalization with TH-IR was observed in DMV neurons. These findings suggest that TH-IR neurons in the caudal DMV project mainly to the gastric corpus, constitute a subpopulation distinct from that of nitrergic vagal neurons, and are not activated on esophageal distension.
Esophageal function testing using multichannel intraluminal impedance
Authors: Srinivasan R. , Vela M. F. , Katz P. O. , Tutuian R. , Castell J. A. , Castell D. O.
Published: December 2017

Multichannel intraluminal impedance (MII) is a new technique for evaluation of bolus transport. We evaluated esophageal function using bolus transport time (BTT) and contraction wave velocity (CWV) of liquid, semisolid, and solid boluses. Ten healthy subjects underwent MII swallow evaluation with various boluses of sterile water (pH 5), applesauce, three different sized marshmallows, and iced and 130°F water. The effect of bethanechol was also studied. There was no difference in BTT or CWV for all water volumes from 1 to 20 ml. There was significant linear increase of BTT with progressively larger volumes of applesauce, and BTT of applesauce was longer than for water. BTT was significantly longer with large marshmallows vs. small and medium and was longer than for water. BTT for iced water was similar to 130°F water. Applesauce showed a significant linear decrease of CWV with progressively larger volumes and was slower than water. Marshmallow showed significantly slower CWV with the large vs. small, and CWV for ice water was significantly slower than 130°F water. Therefore, BTT of liquid is constant, whereas BTT of semisolid and solid are volume dependent and longer than liquids. CWV of semisolids and solids are slower than liquids. CWV of cold liquids is slower than warm liquids. MII can be used as a discriminating test of esophageal function.
Sensory pathways and cyclooxygenase regulate mucus gel thickness in rat duodenum
Authors: Akiba Yasutada , Furukawa Osamu , Guth Paul H. , Engel Eli , Nastaskin Igor , Kaunitz Jonathan D.
Published: December 2017

We previously showed that the duodenal hyperemic response to acid occurs through activation of capsaicin-sensitive afferent nerves with subsequent release of vasodilatory substances such as calcitonin gene-related peptide (CGRP) and nitric oxide. We then tested the hypothesis that similar factors regulate duodenal mucus gel thickness. Gel thickness was optically measured using in vivo microscopy in anesthetized rats. Duodenal mucosae were superfused with pH 7.0 buffer with vanilloid receptor agonist capsaicin, bradykinin, or PGE2 injection or were challenged with pH 2.2 solution, with or without the vanilloid antagonist capsazepine, human CGRP-(8–37), N G-nitro-l-arginine methyl ester, and indomethacin. Other rats underwent sensory ablation with high-dose capsaicin pretreatment. Acid, bradykinin, capsaicin, and PGE2 all quickly thickened the gel. Antagonism of vanilloid and CGRP receptors, inhibition of nitric oxide synthase, and sensory deafferentation delayed gel thickening, suggesting that the capsaicin pathway mediated the initial burst of mucus secretion that thickened the gel. Indomethacin abolished gel thickening due to acid, bradykinin, and capsaicin. Inhibition of gel thickening by indomethacin in response to multiple agonists suggests that cyclooxygenase activity is essential for duodenal gel thickness regulation. Duodenal afferent neural pathways play an important role in the modulation of cyclooxygenase-mediated physiological control of gel thickness.
Interleukin-1β enhances retinoic acid-mediated expression of bone-type alkaline phosphatase in rat IEC-6 cells
Authors: Nikawa Takeshi , Ikemoto Madoka , Tokuoka Kaori , Teshima Shigetada , Alpers David H. , Masui Yoshihiro , Kishi Kyoichi , Rokutan Kazuhito
Published: December 2017

We previously showed that vitamin A upregulated the expression of bone-type alkaline phosphatase (ALP) in fetal rat small intestine and rat intestinal IEC-6 cells. In this study, we examined interactions between retinoic acid (RA) and several growth factors/cytokines on the isozyme expression in IEC-6 cells. Epidermal growth factor and interleukins (ILs)-2, -4, -5, and -6 completely blocked the RA-mediated increase in ALP activity. In contrast, IL-1β markedly increased the activity, protein, and mRNA of the bone-type ALP only when RA was present. IL-1β and/or RA did not change the type 1 IL-1 receptor transcript level, whereas IL-1β enhanced the RA-induced expressions of retinoic acid receptor-β (RAR-β) and retinoid X receptor-β (RXR-β) mRNAs and RA-mediated RXR response element binding. The synergism of IL-1β and RA on ALP activity was completely blocked by protein kinase C (PKC) inhibitors. Our results suggest that IL-1β may modify the ALP isozyme expression in small intestinal epithelial cells by stimulating PKC-dependent, RAR-β- and/or RXR-β-mediated signaling pathways.
Inflammation enhances reflex and spinal neuron responses to noxious visceral stimulation in rats
Authors: Ness T. J. , Gebhart G. F.
Published: December 2017

To improve understanding of sensory processes related to visceral inflammation, the effect of turpentine-induced inflammation on reflex (cardiovascular/visceromotor) and extracellularly recorded lumbosacral dorsal horn neuron responses to colorectal distension (CRD) was investigated. A 25% solution of turpentine, applied to the colorectal mucosa, produced inflammation, decreased compliance of the colonic wall, and enhanced reflex responses in unanesthetized rats within 2–6 h. At 24 h posttreatment, pressor responses to CRD (80 mmHg, 20 s) were 20% greater, and intraluminal pressures needed to evoke visceromotor reflexes were 30% lower than controls. Parallel electrophysiological experiments in spinal cord-transected, decerebrate rats demonstrated that two neuronal subgroups excited by CRD were differentially affected by turpentine administered 24 h before testing. During CRD, abrupt neurons were 70% less active and sustained neurons were 25% more active than similar neurons in controls. In summary, reflex and neuronal subgroup (sustained neurons) responses to CRD were both potentiated by chemical inflammation. This suggests that the neurophysiological basis for inflammation-induced increases in reflex responses to CRD is increased activity of this neuronal subgroup.
Interleukin-5 inhibition of biliary cell chloride currents and bile flow
Authors: McGill James M. , Yen Margaret S. , Cummings Oscar W. , Alpini Gianfranco , LeSage Gene , Pollok Karen E. , Miller Barbara , Engle Steven K. , Stansfield Ann P.
Published: December 2017

Recent studies have detected significant elevations of interleukin (IL)-5 mRNA in the liver parenchyma of patients with both primary biliary cirrhosis and acute rejection after liver transplantation. In both of these disorders, intrahepatic biliary epithelial cells (BECs) are the targets of injury. We hypothesized that BECs may themselves express IL-5 receptors that may modulate key biliary functions. RNAs coding for IL-5α and -β receptors were amplified by RT/PCR from a biliary cell line derived from a human cholangiocarcinoma (Mz-ChA-1) and verified by DNA sequencing. IL-5 receptor distribution was detected immunocytochemically on Mz-ChA-1 cells, immortalized murine BEC, bile duct-ligated rat liver, and isolated cholangiocytes. Patch-clamp studies on Mz-ChA-1 cells showed that IL-5 inhibits 5′- N-ethylcarboxamidoadenosine-stimulated chloride currents. Additional functional studies showed that IL-5 inhibits secretin-induced bile flow. We conclude that BECs express IL-5 receptors and that IL-5 modulates BEC chloride currents and fluid secretion. Since IL-5 has previously been associated with cholestatic liver disease, we speculate that IL-5 may contribute to liver injury through its effects on biliary secretion.
Effect ofSchistosoma mansoni-induced granulomatous inflammation on murine gastrointestinal motility
Authors: Moreels Tom G. , De Man Joris G. , Bogers Johannes J. , De Winter Benedicte Y. , Vrolix Gunther , Herman Arnold G. , Van Marck Eric A. , Pelckmans Paul A.
Published: December 2017

In Schistosoma mansoni-infected mice, gastrointestinal transit was measured in vivo and the neuromuscular function of longitudinal muscle strips of inflamed ileum and noninflamed gastric fundus was assessed in vitro. Eight weeks after infection, the ileal wall was acutely inflamed, as shown by a mucosal inflammatory infiltrate, leading to an increase in mucosal thickness, in myeloperoxidase (MPO) activity, and in interleukin (IL)-1β production. At that time, both gastrointestinal transit and in vitro ileal contractility were normal. Twelve weeks after infection, chronic granulomatous inflammation led to proliferation of the muscle layer and to a further increase in MPO activity, whereas IL-1β production normalized. Gastrointestinal transit was decreased, whereas in vitro ileal contractility was increased irrespective of the contractile stimulus. In vitro incubation with IL-1β (10 ng/ml for 60 min) significantly increased ileal contractility only at 8 wk after infection. Indomethacin, tetrodotoxin, and atropine had no differential effect on ileal contractility in controls and infected mice. In vitro contractility of noninflamed gastric fundus was normal both 8 and 12 wk after infection. We conclude that intestinal schistosomiasis 8 wk after infection is associated only with structural changes of the ileum, whereas 12 wk after infection, both structural and functional changes are present. These changes are characterized by increased ileal wall thickness, decreased gastrointestinal transit, and increased smooth muscle contractility restricted to the inflamed gut segment.
Human biliary mucin binds to E-selectin: a possible role in modulation of inflammation
Authors: Sreejayan Nair , Wittig Bianca M. , von Stillfried Niko , Hennicke Matthias S. , Meyer Gunther , Stieber Petra , Lamerz Rolf , von Ritter Christoph
Published: December 2017

E-selectin, expressed on endothelial cells, mediates adhesion of leukocytes and tumor cells to endothelium. CA19-9 (sialyl-Lewisa) and sialyl-Lewisxare specific ligands for E-selectin. We have recently shown that mucin-rich culture media from human gallbladder epithelial cells contains CA19-9. In this study, we have tested whether human biliary mucin binds to E-selectin. The ability of mucins to inhibit the adhesion of HL-60 cells to immobilized E-selectin was taken as an index for E-selectin binding. Gallbladder bile, hepatic bile, and culture medium from human gallbladder epithelial cells completely inhibited the adhesion of HL-60 cells to E-selectin. The mucin-rich fractions of human bile exhibited strong inhibition, whereas mucin-free fractions had little effect. In contrast to human bile samples, CA19-9-free medium from cultured dog gallbladder epithelial cells failed to inhibit HL-60 binding. Furthermore, after CA19-9 immunoaffinity chromatography, which selectively extracted CA19-9 from bile, bile samples showed poor inhibition of HL-60 adhesion to immobilized E-selectin. A good correlation was observed between E-selectin binding and CA 19-9 concentrations in bile. Our results show that human bile has E-selectin binding activity that is mediated by the CA19-9 side chain of biliary mucin.
Effects of systemic arterial hypoperfusion on splanchnic hemodynamics and hepatic arterial buffer response in pigs
Authors: Jakob S. M. , Tenhunen J. J. , Laitinen S. , Heino A. , Alhava E. , Takala J.
Published: December 2017

The hepatic arterial buffer response (HABR) tends to maintain liver blood flow under conditions of low mesenteric perfusion. We hypothesized that systemic hypoperfusion impairs the HABR. In 12 pigs, aortic blood flow was reduced by cardiac tamponade to 50 ml · kg−1· min−1for 1 h (short-term tamponade) and further to 30 ml · kg−1· min−1for another hour (prolonged tamponade). Twelve pigs without tamponade served as controls. Portal venous blood flow decreased from 17 ± 3 (baseline) to 6 ± 4 ml · kg−1· min−1(prolonged tamponade; P = 0.012) and did not change in controls, whereas hepatic arterial blood flow decreased from 2 ± 1 (baseline) to 1 ± 1 ml · kg−1· min−1(prolonged tamponade; P = 0.050) and increased from 2 ± 1 to 4 ± 2 ml · kg−1· min−1in controls ( P = 0.002). The change in hepatic arterial conductance (Δ Cha) during acute portal vein occlusion decreased from 0.1 ± 0.05 (baseline) to 0 ± 0.01 ml · kg−1· min−1· mmHg−1(prolonged tamponade; P = 0.043). In controls, Δ Chadid not change. Hepatic lactate extraction decreased, but hepatic release of glutathione S-transferase A did not change during cardiac tamponade. In conclusion, during low systemic perfusion, the HABR is exhausted and hepatic function is impaired without signs of cellular damage.
Alterations in spontaneous contractions in vitro after repeated inflammation of rat distal colon
Authors: Bossone Carol , Hosseini Jeanette M. , Piñeiro-Carrero Victor , Shea-Donohue Terez
Published: December 2017

In inflammatory bowel disease, smooth muscle function reportedly varies with disease duration. The aim of these studies was to determine changes in the control of spontaneous contractions in a model of experimental colitis that included reinflammation of the healed area. The amplitude and frequency of spontaneous contractions in circular smooth muscle were determined after intrarectal administration of trinitrobenzenesulfonic acid in rat distal colon. With the use of a novel paradigm, rats were studied 4 h (acute) or 28 days (healed) after the initial inflammation. At 28 days, rats were studied 4 h after a second inflammation (reinflamed) of the colon. Colitis induced transient increases in the amplitude of spontaneous contractions coincident with a loss of nitric oxide synthase activity. The frequency of contractions was controlled by constitutive nitric oxide in controls. Frequency was increased in healed and reinflamed colon and was associated with a shift in the dominance of neural constitutive nitric oxide synthase control to that of inducible nitric oxide synthase (iNOS). The initial colitis induced a remodeling of the neural control of spontaneous contractions reflecting changes in their regulation by constitutive nitric oxide synthase and iNOS.
Mast cells are involved in the gastric hyperemic response to acid back diffusion via release of histamine
Authors: Rydning Astrid , Lyng Oddveig , Adamsen Birgitte Lid , Falkmer Sture , Sandvik Arne K. , Grønbech Jon Erik
Published: December 2017

Acid back diffusion into the rat stomach mucosa leads to gastric vasodilation. We hypothesized that histamine, if released from the rat mucosa under such conditions, is mast cell derived and involved in the vasodilator response. Gastric blood flow (GBF) and luminal histamine were measured in an ex vivo chamber. Venous histamine was measured from totally isolated stomachs. Mucosal mast cells (MMC), submucosal connective tissue mast cells (CTMC), and chromogranin A-immunoreactive cells (CgA IR) were assessed morphometrically. After mucosal exposure to 1.5 M NaCl, the mucosa was subjected to saline at pH 5.5 (control) or pH 1.0 (H+back diffusion) for 60 min. H+back diffusion evoked a marked gastric hyperemia, increase of luminal and venous histamine, and decreased numbers of MMC and CTMC. CgA IR cells were not influenced. Depletion of mast cells with dexamethasone abolished (and stabilization of mast cells with ketotifen attenuated) both hyperemia and histamine release in response to H+back diffusion. GBF responses to H+back diffusion were attenuated by H1and abolished by H3but not H2receptor blockers. Our data conform to the idea that mast cells are involved in the gastric hyperemic response to acid back diffusion via release of histamine.
Acute adaptive cellular base uptake in rat duodenal epithelium
Authors: Akiba Yasutada , Furukawa Osamu , Guth Paul H. , Engel Eli , Nastaskin Igor , Kaunitz Jonathan D.
Published: December 2017

We studied the role of duodenal cellular ion transport in epithelial defense mechanisms in response to rapid shifts of luminal pH. We used in vivo microscopy to measure duodenal epithelial cell intracellular pH (pHi), mucus gel thickness, blood flow, and HCO[Formula: see text] secretion in anesthetized rats with or without the Na+/H+exchange inhibitor 5-( N, N-dimethyl)-amiloride (DMA) or the anion transport inhibitor DIDS. During acid perfusion pHidecreased, whereas mucus gel thickness and blood flow increased, with pHiincreasing to over baseline (overshoot) and blood flow and gel thickness returning to basal levels during subsequent neutral solution perfusion. During a second brief acid challenge, pHidecrease was lessened (adaptation). These are best explained by augmented cellular HCO[Formula: see text] uptake in response to perfused acid. DIDS, but not DMA, abolished the overshoot and pHiadaptation and decreased acid-enhanced HCO[Formula: see text] secretion. In perfused duodenum, effluent total CO2output was not increased by acid perfusion, despite a massive increase of titratable alkalinity, consistent with substantial acid back diffusion and modest CO2back diffusion during acid perfusions. Rapid shifts of luminal pH increased duodenal epithelial buffering power, which protected the cells from perfused acid, presumably by activation of Na+-HCO[Formula: see text] cotransport. This adaptation may be a novel, important, and early duodenal protective mechanism against rapid physiological shifts of luminal acidity.
Effect of hyperthermia on NF-κB binding activity in cerulein-induced acute pancreatitis
Authors: Frossard Jean Louis , Pastor Catherine M. , Hadengue Antoine
Published: December 2017

Although the pancreatic heat shock response has already been reported to confer protective effects during experimental pancreatitis, the mechanism of action remains unknown. We investigated the effects of hyperthermia in cerulein-induced pancreatitis. Heat shock protein 70 (HSP70) expression in rats was induced by a 20-min period of water immersion (42°C). The severity of pancreatitis as well as the pancreatic expression of cytokines, nuclear factor-κB (NF-κB), and inhibitory factor κB-α (IκB-α) were evaluated in the presence and absence of hyperthermia. We found that hyperthermia resulted in time-dependent expression of HSP70 within the pancreas associated with a reduction in the severity of acute pancreatitis. Tumor necrosis factor-α and intercellular adhesion molecule-1 expression was significantly reduced in the presence of hyperthermia. Moreover, NF-κB activity was delayed in the presence of hyperthermia whereas IκB-α was stabilized in the cytoplasm. These results suggest that hyperthermia decreases the severity of cerulein-induced pancreatitis by decreasing cytokine expression in the pancreas through the modulation of NF-κB activity.
Regulation of hepatic eNOS by caveolin and calmodulin after bile duct ligation in rats
Authors: Shah Vijay , Cao Sheng , Hendrickson Helen , Yao Janet , Katusic Zvonimir S.
Published: December 2017

In carbon tetrachloride-induced liver cirrhosis, diminution of hepatic endothelial nitric oxide synthase (eNOS) activity may contribute to impaired hepatic vasodilation and portal hypertension. The mechanisms responsible for these events remain unknown; however, a role for the NOS-associated proteins caveolin and calmodulin has been postulated. The purpose of this study is to characterize the expression and cellular localization of the NOS inhibitory protein caveolin-1 in normal rat liver and to then examine the role of caveolin in conjunction with calmodulin in regulation of NOS activity in cholestatic portal hypertension. In normal liver, caveolin protein is expressed preferentially in nonparenchymal cells compared with hepatocytes as assessed by Western blot analysis of isolated cell preparations. Additionally, within the nonparenchymal cell populations, caveolin expression is detected within both liver endothelial cells and hepatic stellate cells. Next, studies were performed 4 wk after bile duct ligation (BDL), a model of portal hypertension characterized by prominent cholestasis, as evidenced by a significant increase in serum cholesterol in BDL animals. After BDL, caveolin protein levels from detergent-soluble liver lysates are significantly increased as assessed by Western blot analysis. Immunoperoxidase staining demonstrates that this increase is most prominent within sinusoids and venules. Additionally, caveolin-1 upregulation is associated with a significant reduction in NOS catalytic activity in BDL liver lysates, an event that is corrected with provision of excess calmodulin, a protein that competitively binds eNOS from caveolin. We conclude that, in cholestatic portal hypertension, caveolin may negatively regulate NOS activity in a manner that is reversible by excess calmodulin.
Characteristics of rodent intestinal mucin Muc3 and alterations in a mouse model of human cystic fibrosis
Authors: Khatri Ismat A. , Ho Catherine , Specian Robert D. , Forstner Janet F.
Published: December 2017

Human mucin MUC3 and rodent Muc3 are widely assumed to represent secretory mucins expressed in columnar and goblet cells of the intestine. Using a 3′-oligonucleotide probe and in situ hybridization, we observed expression of rat Muc3 mostly in columnar cells. Two antibodies specific for COOH-terminal epitopes of Muc3 localized to apical membranes and cytoplasm of columnar cells. An antibody to the tandem repeat (TR) sequence (TTTPDV)3, however, localized to both columnar and goblet cells. On CsCl gradients, Muc3 appeared in both light- and heavy-density fractions. The lighter species was immunoreactive with all three antibodies, whereas the heavier species reacted only with anti-TR antibody. Thus Muc3 is expressed in two forms, a full-length membrane-associated form found in columnar cells (light density) and a carboxyl-truncated soluble form present in goblet cells (heavy density). In a mouse model of human cystic fibrosis, both soluble Muc3 and goblet cell Muc2 were increased in amount and hypersecreted. Thus Muc2 and Muc3 contribute to the excess intestinal luminal mucus of cystic fibrosis mice.
Neutrophil adhesion is impaired in the mesentery but not in the liver sinusoids of portal hypertensive rats
Authors: Pérez-del-Pulgar Sofía , Pizcueta Pilar , Engel Pablo , Bosch Jaume , Rodés Joan
Published: December 2017

Altered leukocyte/cytokine response to inflammation has been observed in human and experimental portal hypertension. The aim of this study was to characterize leukocyte adhesion in portal hypertensive (PPVL) rats stimulated with endotoxin. Leukocyte rolling, adhesion, and migration assessed by intravital microscopy were impaired in mesenteric venules after lipopolysaccharide administration (150 μg/kg) in PPVL vs. sham-operated rats. Analysis of leukocyte L-selectin expression and soluble L-selectin showed that this defective adhesion was related to increased L-selectin shedding. In vitro experiments using isolated leukocytes treated with phorbol 12-myristate 13-acetate showed that monocytes and neutrophils but not lymphocytes were hyperreactive to cell activation, as measured by CD11b overexpression and increased L-selectin shedding in PPVL rats. However, neutrophil emigration in liver sinusoids and in the lung 3 h after endotoxin injection were similar in both groups of animals. Thus the alterations in leukocyte activation and adhesion molecule expression observed in this study may contribute to a better understanding of the higher susceptibility and severity of bacterial infections in cirrhotic patients with portal hypertension.
Abnormal gastric slow waves in patients with functional dyspepsia assessed by multichannel electrogastrography
Authors: Lin Xuemei , Chen Jiande Z.
Published: December 2017

The aim of this study was to utilize multichannel electrogastrography to investigate whether patients with functional dyspepsia had impaired propagation or coordination of gastric slow waves in the fasting state compared with healthy controls. The study was performed in 10 patients with functional dyspepsia and 11 healthy subjects. Gastric myoelectrical activity was measured by using surface electrogastrography with a specially designed four-channel device. The study was performed for 30 min or more in the fasting state. Special computer programs were developed for the computation of the propagation and coupling of the gastric slow wave. It was found that, compared with the healthy controls, the patients showed a significantly lower percentage of slow wave propagation (58.0 ± 8.9 vs. 89.9 ± 2.6%, P < 0.002) and a significantly lower percentage of slow wave coupling (46.9 ± 4.4 vs. 61.5 ± 6.9%, P < 0.04). In addition, the patients showed inconsistencies in the frequency and regularity of the gastric slow wave among the four-channel electrogastrograms (EGGs). It was concluded that patients with functional dyspepsia have impaired slow wave propagation and coupling. Multichannel EGG has more information than single-channel EGG for the detection of gastric myoelectrical abnormalities.
Adaptive vasodilatory response after octreotide treatment
Authors: Yang Ying-Ying , Lin Han-Chieh , Huang Yi-Tsau , Lee Tzung-Yan , Lee Wui-Chiang , Hou Ming-Chih , Lee Fa-Yauh , Chang Full-Young , Lee Shou-Dong
Published: December 2017

Despite the suppression of glucagon release, an adaptive response aimed at maintaining vasodilatation after octreotide treatment may exist in portal hypertension. The present study was undertaken to evaluate the possible interaction between endothelium and non-endothelium-derived vasodilators after 1-wk octreotide administration in cirrhotic rats. Rats were allocated to receive either vehicle or octreotide (30 or 100 μg/kg every 12 h subcutaneously). Hemodynamic values, plasma glucagon levels, endothelium-related vasodilatory activities, and aortic endothelial nitric oxide synthase (eNOS) expression were determined after treatment. Octreotide administration decreased plasma glucagon and increased serum 6-keto-PGF1α and NOx levels without affecting the hemodynamic values. In cirrhotic rats receiving octreotide, there was a blunt response to either l-NAME or indomethacin administration alone, but this blunt pressor response disappeared after simultaneous administration of the two drugs. Additionally, an increased aortic eNOS expression was observed in cirrhotic rats receiving 1-wk octreotide. It is concluded that 1-wk octreotide treatment did not correct the hemodynamic derangement in cirrhotic rats. The enhanced endothelium-related vasodilatory activity was noted after octreotide treatment that overcame the octreotide-induced hemodynamic effects in portal hypertension.
Inhibition of gastrointestinal lipolysis by Orlistat during digestion of test meals in healthy volunteers
Authors: Carrière Frédéric , Renou Christophe , Ransac Stéphane , Lopez Véronique , De Caro Josiane , Ferrato Francine , De Caro Alain , Fleury André , Sanwald-Ducray Patricia , Lengsfeld Hans , Beglinger Christoph , Hadvary Paul , Verger Robert , Laugier René
Published: December 2017

The inhibition of digestive lipases by the antiobesity drug Orlistat along with lipolysis levels and fecal fat excretion were measured in healthy humans. Orlistat was found to be a powerful gastric lipase inhibitor, achieving 46.6–91.4% enzyme inhibition and thus greatly reducing gastric lipolysis of solid and liquid meals (11–33% of respective controls). Gastric lipase inhibition by Orlistat was extremely fast (half-inhibition time < 1 min). Duodenal lipolysis was reduced significantly by Orlistat given with the solid meal (32.6–37.6% of controls) but was only slightly reduced by Orlistat given with the liquid meal (74.5–100% of controls). Human pancreatic lipase (HPL) inhibition was found to be high (51.2–82.6%), however, regardless of the meal. These paradoxical results were explained when in vitro lipolysis experiments were performed. The rates of HPL inhibition by Orlistat were found to be similar with both types of meals (half-inhibition time 5–6 min), but the preemulsified triglycerides of the liquid meal were rapidly hydrolyzed by HPL before the enzyme was significantly inhibited by Orlistat. With the solid meal, the rate of hydrolysis of the meal triglycerides by HPL was slower than the rate of HPL inhibition by Orlistat. As predicted from the previous results, the effects of Orlistat on fat excretion levels were found to be much greater with the solid (40.5–57.4% of ingested fat) than with the liquid (4.2–18.8%) test meal.
Inflammatory bowel disease is associated with changes of enterocytic junctions
Authors: Gassler Nikolaus , Rohr Claudia , Schneider Armin , Kartenbeck Jürgen , Bach Alfred , Obermüller Nicholas , Otto Herwart F. , Autschbach Frank
Published: December 2017

Changes of the intestinal mucosal barrier are considered to play a role in the pathogenesis of inflammatory bowel disease (IBD). Our experiments were designed to identify dysregulation of epithelial junctional molecules in the IBD intestinum and to address whether altered expression of these molecules is a primary event in IBD or a phenomenon secondary to the inflammatory process. Noninflamed and inactively and actively inflamed mucosal tissues from patients with ulcerative colitis or Crohn's disease as well as tissues from control subjects were analyzed for the expression of junctional molecules by different methods. Marked downregulation of junctional proteins and their respective mRNAs was observed in actively inflamed IBD tissues. In IBD tissues with inactive inflammation, only a few junctional molecules such as E-cadherin and α-catenin were affected, whereas expression of desmosomal or tight junction-associated proteins appeared almost unchanged. In noninflamed IBD tissues, junctional protein expression was not different from that seen in normal control subjects. In IBD, downregulation of junctional molecule expression is apparently associated with the inflammatory process and does not likely represent a primary phenomenon.
Impaired biliary lipid secretion in obese Zucker rats: leptin promotes hepatic cholesterol clearance
Authors: VanPatten Sonya , Ranginani Narasimha , Shefer Sarah , Nguyen Lien B. , Rossetti Luciano , Cohen David E.
Published: December 2017

Human obesity is associated with elevated plasma leptin levels. Obesity is also an important risk factor for cholesterol gallstones, which form as a result of cholesterol hypersecretion into bile. Because leptin levels are correlated with gallstone prevalence, we explored the effects of acute leptin administration on biliary cholesterol secretion using lean ( FA/−) and obese ( fa/fa) Zucker rats. Zucker ( fa/fa) rats become obese and hyperleptinemic due to homozygosity for a missense mutation in the leptin receptor, which diminishes but does not completely eliminate responsiveness to leptin. Rats were infused intravenously for 12 h with saline or pharmacological doses of recombinant murine leptin (5 μg · kg−1· min−1) sufficient to elevate plasma leptin concentrations to 500 ng/ml compared with basal levels of 3 and 70 ng/ml in lean and obese rats, respectively. Obesity was associated with a marked impairment in biliary cholesterol secretion. In biles of obese compared with lean rats, bile salt hydrophobicity was decreased whereas phosphatidylcholine hydrophobicity was increased. High-dose leptin partially normalized cholesterol secretion in obese rats without altering lipid compositions, implying that both chronic effects of obesity and relative resistance to leptin contributed to impaired biliary cholesterol elimination. In lean rats, acute leptin administration increased biliary cholesterol secretion rates. Without affecting hepatic cholesterol contents, leptin downregulated hepatic activity of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, upregulated activities of both sterol 27-hydroxylase and cholesterol 7α-hydroxylase, and lowered plasma very low-density lipoprotein cholesterol concentrations. Increased biliary cholesterol secretion in the setting of decreased cholesterol biosynthesis and increased catabolism to bile salts suggests that leptin promotes elimination of plasma cholesterol.
V. Fast and slow extrinsic modulation of dorsal vagal complex circuits
Authors: Travagli R. Alberto , Rogers Richard C.
Published: December 2017

Vago-vagal reflex circuits in the medulla are responsible for the smooth coordination of the digestive processes carried out from the oral cavity to the transverse colon. In this themes article, we concentrate mostly on electrophysiological studies concerning the extrinsic modulation of these vago-vagal reflex circuits, with a particular emphasis on two types of modulation, i.e., by “fast” classic neurotransmitters and by “slow” neuromodulators. These examples review two of the most potent modulatory processes at work within the dorsal vagal complex, which have dramatic effects on gastrointestinal function. The reader should be mindful of the fact that many more different inputs from other central nervous system (CNS) loci or circulating humoral factors add to this complex mix of modulatory inputs. It is likely that similar long-term modulations of synaptic transmission occur with other neurotransmitters and may represent an important mechanism for the integration and regulation of neuronal behavior. Of course, this fact strongly militates against the success of any single drug or approach in the treatment of motility disorders having a CNS component.
Spontaneous water secretion in T84 cells: effects of STa enterotoxin, bumetanide, VIP, forskolin, and A-23187
Authors: Toriano Roxana , Kierbel Arlinet , Ramirez Marco Antonio , Malnic Gerhard , Parisi Mario
Published: December 2017

The regulated Cl− secretory apparatus of T84 cells responds to several pharmacological agents via different second messengers (Ca2+, cAMP, cGMP). However, information about water movements in T84 cells has not been available. In the absence of osmotic or chemical gradient, we observed a net secretory transepithelial volume flux ( J w = −0.16 ± 0.02 μl · min−1 · cm−2) in parallel with moderate short-circuit current values ( I sc = 1.55 ± 0.23 μA/cm2). The secretory J wreversibly reverted to an absorptive value when A-23187 was added to the serosal bath. Vasoactive intestinal polypeptide increased I sc, but, unexpectedly, J w was not affected. Bumetanide, an inhibitor of basolateral Na+-K+-2Cl−cotransporter, completely blocked secretory J wwith no change in I sc. Conversely, serosal forskolin increased I sc, but J w switched from secretory to absorptive values. Escherichia coli heat-stable enterotoxin increased secretory J w and I sc. No difference between the absorptive and secretory unidirectional Cl−fluxes was observed in basal conditions, but after STa stimulation, a significant net secretory Cl− flux developed. We conclude that, under these conditions, the presence of secretory or absorptive J w values cannot be shown by I sc and ion flux studies. Furthermore, RT-PCR experiments indicate that aquaporins were not expressed in T84 cells. The molecular pathway for water secretion appears to be transcellular, moving through the lipid bilayer or, as recently proposed, through water-solute cotransporters.
PKC-β1 mediates EGF protection of microtubules and barrier of intestinal monolayers against oxidants
Authors: Banan A. , Fields J. Z. , Talmage D. A. , Zhang Yang , Keshavarzian A.
Published: December 2017

Using monolayers of human intestinal (Caco-2) cells, we found that oxidants and ethanol damage the cytoskeleton and disrupt barrier integrity; epidermal growth factor (EGF) prevents damage by enhancement of protein kinase C (PKC) activity and translocation of the PKC-β1 isoform. To see if PKC-β1 mediates EGF protection, cells were transfected to stably over- or underexpress PKC-β1. Transfected monolayers were preincubated with low or high doses of EGF (1 or 10 ng/ml) or 1-oleoyl-2-acetyl- sn-glycerol [OAG; a PKC activator (0.01 or 50 μM)] before treatment with oxidant (0.5 mM H2O2). Only in monolayers overexpressing PKC-β1 (3.1-fold) did low doses of EGF or OAG initiate protection, increase tubulin polymerization (assessed by quantitative immunoblotting) and microtubule architectural integrity (laser scanning confocal microscopy), maintain normal barrier permeability (fluorescein sulfonic acid clearance), and cause redistribution of PKC-β1 from cytosolic pools into membrane and/or cytoskeletal fractions (assessed by immunoblotting), thus indicating PKC-β1 activation. Antisense inhibition of PKC-β1 expression (−90%) prevented these changes and abolished EGF protection. We conclude that EGF protection against oxidants requires PKC-β1 isoform activation. This mechanism may be useful for development of novel therapies for the treatment of inflammatory gastrointestinal disorders including inflammatory bowel disease.
Vagal afferent responses to fatty acids of different chain length in the rat
Authors: Lal Simon , Kirkup Anthony J. , Brunsden Alan M. , Thompson David G. , Grundy David
Published: December 2017

The role of cholecystokinin (CCK) in the effect of dietary lipid on proximal gastrointestinal function and satiety is controversial. Recent work suggests that fatty acid chain length may be a determining factor. We investigated the mechanism by which long- and short-chain fatty acids activate jejunal afferent nerves in rats. Whole mesenteric afferent nerve discharge was recorded in anaesthetized male Wistar rats during luminal perfusion of saline, sodium oleate, and sodium butyrate (both 10 mM). Both fatty acids evoked characteristic afferent nerve responses, distinct from the mechanical response to saline, that were abolished in rats following chronic subdiaphragmatic vagotomy. The effect of oleate was abolished by the CCK-A receptor antagonist Devazepide (0.5 mg/kg), whereas the effect of butyrate persisted despite pretreatment with either Devazepide or a combination of the calcium channel inhibitors nifedipine (1 mg/kg) and the ω-conotoxins GVIA and SVIB (each 25 μg/kg). In summary, long- and short-chain fatty acids activate intestinal vagal afferents by different mechanisms; oleate acts via a CCK-mediated mechanism and butyrate appears to have a direct effect on afferent terminals.