bluuebunny/crossref_metadata_2025 huggingface dataset:
Processing of vegetable-borne carotenoids in the human stomach and duodenum
Authors: Tyssandier Viviane , Reboul Emmanuelle , Dumas Jean-François , Bouteloup-Demange Corinne , Armand Martine , Marcand Julie , Sallas Marcel , Borel Patrick
Published: March 2015

Carotenoids are thought to diminish the incidence of certain degenerative diseases, but the mechanisms involved in their intestinal absorption are poorly understood. Our aim was to obtain basic data on the fate of carotenoids in the human stomach and duodenum. Ten healthy men were intragastrically fed three liquid test meals differing only in the vegetable added 3 wk apart and in a random order. They contained 40 g sunflower oil and mashed vegetables as the sole source of carotenoids. Tomato purée provided 10 mg lycopene as the main carotenoid, chopped spinach (10 mg lutein), and carrot purée (10 mg β-carotene). Samples of stomach and duodenal contents and blood samples were collected at regular time intervals after meal intake. all -trans and ciscarotenoids were assayed in stomach and duodenal contents, in the fat and aqueous phases of those contents, and in chylomicrons. The cis-trans β-carotene and lycopene ratios did not significantly vary in the stomach during digestion. Carotenoids were recovered in the fat phase present in the stomach during digestion. The proportion of all -trans carotenoids found in the micellar phase of the duodenum was as follows (means ± SE): lutein (5.6 ± 0.4%), β-carotene (4.7 ± 0.3%), lycopene (2.0 ± 0.2%). The proportion of 13- cis β-carotene in the micellar phase was significantly higher (14.8 ± 1.6%) than that of the all -trans isomer (4.7 ± 0.3%). There was no significant variation in chylomicron lycopene after the tomato meal, whereas there was significant increase in chylomicron β-carotene and lutein after the carrot and the spinach meals, respectively. There is no significant cis-transisomerization of β-carotene and lycopene in the human stomach. The stomach initiates the transfer of carotenoids from the vegetable matrix to the fat phase of the meal. Lycopene is less efficiently transferred to micelles than β-carotene and lutein. The very small transfer of carotenoids from their vegetable matrices to micelles explains the poor bioavailability of these phytomicroconstituents.
LPS-induced suppression of gastric motility relieved by TNFR:Fc construct in dorsal vagal complex
Authors: Hermann Gerlinda E. , Tovar C. Amy , Rogers Richard C.
Published: March 2015

Our previous studies suggested that the cytokine tumor necrosis factor-α (TNF-α) may act within the neural circuitry of the medullary dorsal vagal complex (DVC) to affect changes in gastric function, such as gastric stasis, loss of appetite, nausea, and vomiting. The definitive demonstration that endogenously generated TNF-α is capable of affecting gastric function via the DVC circuitry has been impeded by the lack of an antagonist for TNF-α. The present studies used localized central nervous system applications of the TNF-adsorbant construct (TNFR:Fc; TNF-receptor linked to the Fc portion of the human immunoglobulin IgG1) to attempt to neutralize the suppressive effects of endogenously produced TNF-α. Gastric motility of thiobutabarbital-anesthetized rats was monitored after systemic administration of lipopolysaccharide (LPS) to induce TNF-α production. Continuous perfusion of the floor of the fourth ventricle with TNFR:Fc reversed the potent gastroinhibition induced by LPS, i.e., central thyrotropin-releasing hormone-induced increases in motility were not inhibited. This disinhibition of gastric stasis was not seen after intravenous administration of similar doses of TNFR:Fc nor ventricular application of the Fc fragment of human immunoglobulin. These results validate our previous studies that suggest that circulating TNF-α may act directly within the DVC to affect gastric function in a variety of pathophysiological states.
III. Activity-dependent plasticity in vago-vagal reflexes controlling the stomach
Authors: Travagli R. Alberto , Hermann Gerlinda E. , Browning Kirsteen N. , Rogers Richard C.
Published: March 2015

Vago-vagal reflex circuits modulate digestive functions from the oral cavity to the transverse colon. Previous articles in this series have described events at the level of the sensory receptors encoding the peripheral stimuli, the transmission of information in the afferent vagus, and the conversion of this data within the dorsal vagal complex (DVC) to impulses in the preganglionic efferents. The control by vagal efferents of the postganglionic neurons impinging on the glands and smooth muscles of the target organs has also been illustrated. Here we focus on some of the mechanisms by which these apparently static reflex circuits can be made quite plastic as a consequence of the action of modulatory inputs from other central nervous system sources. A large body of evidence has shown that the neuronal elements that constitute these brain stem circuits have nonuniform properties and function differently according to status of their target organs and the level of activity in critical modulatory inputs. We propose that DVC circuits undergo a certain amount of short-term plasticity that allows the brain stem neuronal elements to act in harmony with neural systems that control behavioral and physiological homeostasis.
III. Bile acids and nuclear receptors
Authors: Chiang John Y. L.
Published: March 2015

Bile acids are physiological detergents that facilitate excretion, absorption, and transport of fats and sterols in the intestine and liver. Recent studies reveal that bile acids also are signaling molecules that activate several nuclear receptors and regulate many physiological pathways and processes to maintain bile acid and cholesterol homeostasis. Mutations of the principal regulatory genes in bile acid biosynthetic pathways have recently been identified in human patients with hepatobiliary and cardiovascular diseases. Genetic manipulation of key regulatory genes and bile acid receptor genes in mice have been obtained. These advances have greatly improved our understanding of the molecular mechanisms underlying complex liver physiology but also raise many questions and controversies to be resolved. These developments will lead to early diagnosis and discovery of drugs for treatment of liver and cardiovascular diseases.
Alcoholic pancreatitis in rats: injury from nonoxidative metabolites of ethanol
Authors: Werner Jens , Saghir Mouris , Warshaw Andrew L. , Lewandrowski Kent B. , Laposata Michael , Iozzo Renato V. , Carter Edward A. , Schatz Richard J. , Fernández-del Castillo Carlos
Published: March 2015

The mechanism by which alcohol injures the pancreas remains unknown. Recent investigations suggest a role for fatty acid ethyl ester (FAEE), a nonoxidative metabolite of ethanol, in the pathogenesis of alcohol pancreatitis. In this study, we characterized ethanol-induced injury in rats and evaluated the contribution of oxidative and nonoxidative ethanol metabolites in this form of acute pancreatitis. Pancreatic injury in rats was assessed by edema, intrapancreatic trypsinogen activation, and microscopy after infusing ethanol with or without inhibitors of oxidative ethanol metabolism. Plasma and tissue levels of FAEE and ethanol were measured and correlated with pancreatic injury. Ethanol infusion generated plasma and tissue FAEE and, in a dose-dependent fashion, induced a pancreas-specific injury consisting of edema, trypsinogen activation, and formation of vacuoles in the pancreatic acini. Inhibition of the oxidation of ethanol significantly increased both FAEE concentration in plasma and pancreas and worsened the pancreatitis-like injury. This study provides direct evidence that ethanol, through its nonoxidative metabolic pathway, can produce pancreas-specific toxicity in vivo and suggests that FAEE are responsible for the development of early pancreatic cell damage in acute alcohol-induced pancreatitis.
V. Mitochondrial dysfunction in steatohepatitis
Authors: Pessayre Dominique , Mansouri Abdellah , Fromenty Bernard
Published: March 2015

Rich diet and lack of exercise are causing a surge in the prevalence of obesity and hepatic steatosis, which causes “primary” steatohepatitis in some patients. Ultrastructural mitochondrial lesions, decreased activity of respiratory chain complexes, and impaired ability to synthesize ATP are observed in these patients. Reactive oxygen species (ROS) may increase tumor necrosis factor-α (TNF-α) production and also oxidize fat deposits. TNF-α and lipid peroxidation products impair the flow of electrons along the respiratory chain, causing overreduction of respiratory chain components and enhanced mitochondrial ROS formation. Steatohepatitis can also be due to alcohol, drugs, or other causes that either directly increase ROS formation or first impair respiration, which secondarily increases ROS formation. Higher ROS formation in secondary steatohepatitis could cause more lipid peroxidation, cytokine induction, and fibrogenesis than in primary steatohepatitis.
S-adenosylmethionine (AdoMet) modulates endotoxin stimulated interleukin-10 production in monocytes
Authors: Song Zhenyuan , Barve Shirish , Chen Theresa , Nelson Wendy , Uriarte Silvia , Hill Daniell , McClain Craig
Published: March 2015

IL-10 is produced by a large variety of cells including monocytes, macrophages, B and T lymphocytes, as well as natural killer cells and is an important suppressor for both immunoproliferative and inflammatory responses. IL-10 exerts antifibrotic effects in the liver, and decreased monocyte synthesis of IL-10 is well documented in alcoholic cirrhosis. Intracellular deficiency of S-adenosylmethionine (AdoMet) is a hallmark of toxin-induced liver injury. Although the administration of exogenous AdoMet attenuates this injury, the mechanisms of its actions are not fully established. This study was performed to investigate the effect of exogenous AdoMet on IL-10 production in LPS-stimulated RAW 264.7 cells, a murine macrophage cell line. Our results demonstrated that exogenous AdoMet administration enhanced both protein production and gene expression of IL-10 in RAW 264.7 cells. Ethionine, an inhibitor for methionine adenosyltransferases, inhibited LPS-stimulated IL-10 both at the protein and mRNA levels. Exogenous AdoMet increased the intracellular cAMP concentration as early as 3 h and continued for 24 h after AdoMet treatment; however, the inhibitors for both adenylyl cyclase and PKA did not significantly affect IL-10 production. On the basis of these results, we conclude that AdoMet administration may exert its anti-inflammatory and hepatoprotective effects, at least in part, by enhancing LPS-stimulated IL-10 production.
Gastric atrial natriuretic peptide regulates endocrine secretion in antrum and fundus of human and rat stomach
Authors: Gower W. R. , Premaratne S. , McCuen R. W. , Arimura A. , McAfee Q. , Schubert M. L.
Published: March 2015

Atrial natriuretic peptide (ANP) is present in gastric mucosa and preferentially binds to two subtypes of natriuretic peptide receptors (NPR), NPR-A and NPR-C. The present study examines the role of endogenous ANP in regulating endocrine secretion in rat and human stomachs. NPR-A protein expression and transcripts were identified in rat antral and fundic mucosa by Western blot and RT-PCR. In superfused rat and human antral and fundic segments, ANP (0.1 pM to 0.1 μM) caused a concentration-dependent increase in somatostatin secretion. In antrum, this was accompanied by a decrease in gastrin, and in fundus, this was accompanied by a decrease in histamine secretion. Changes in gastrin and histamine secretion reflected changes in somatostatin secretion and were abolished by somatostatin antibody. The NPR-A receptor antagonist anantin 1) inhibited basal somatostatin secretion and 2) abolished the somatostatin, gastrin, and histamine responses to ANP. We conclude that endogenous ANP, acting via the NPR-A receptor, stimulates somatostatin secretion from both antrum and fundus of rat and human stomach. Stimulation of somatostatin secretion is coupled to inhibition of gastrin secretion in the antrum and inhibition of histamine secretion in the fundus.
Hypotonicity-induced increases in duodenal mucosal permeability facilitates adjustment of luminal osmolality
Authors: Nylander Olof , Pihl Liselotte , Perry Michael
Published: March 2015

The integrated response to hypotonic NaCl solutions (100, 50, 25, and 0 mM NaCl) in proximal duodenum of anesthetized rats was examined. Luminal alkalinization, fluid flux, duodenal contractions, blood-to-lumen clearance of 51Cr-labeled EDTA (mucosal permeability), and perfusate osmolality were studied in the absence and presence of the cyclooxygenase inhibitor indomethacin. In response to hypotonic solutions net fluid absorption, increases in permeability and perfusate osmolality were markedly higher in indomethacin-treated animals than in controls, and these effects were diminished by the nicotinic-receptor antagonist hexamethonium. Infusion of iloprost, a stable PGI2 analog, to indomethacin-treated animals markedly reduced the hypotonicity-induced increase in mucosal permeability and diminished the rise in perfusate osmolality. Lowering the NaCl concentration in the perfusion solution but maintaining isotonicity with mannitol had no effect on mucosal permeability. Very good linear correlations were obtained between the degree of luminal hypotonicity and the increase in permeability and between increases in permeability and perfusate osmolality. It is concluded that luminal hypotonicity increases duodenal mucosal permeability. The hypotonicity-induced increase in permeability modulated by prostaglandins and nicotinic receptors fulfills the function of increasing blood-to-lumen transport of Na+ facilitating adjustment of luminal osmolality.
Transforming growth factor-β1 downregulation of Smad1 gene expression in rat hepatic stellate cells
Authors: Shen Hong , Huang Guojiang , Hadi Mohammed , Choy Patrick , Zhang Manna , Minuk Gerald Y. , Chen Yongping , Gong Yuewen
Published: March 2015

Smads are intracellular signaling molecules of the transforming growth factor-β (TGF-β) superfamily that play an important role in the activation of hepatic stellate cells (HSCs) and hepatic fibrosis. Excepting the regulation of Smad7, receptor-regulated Smad gene expression is still unclear. We employed rat HSCs to investigate the expression and regulation of the Smad1 gene, which is a bone morphogenetic protein (BMP) receptor-regulated Smad. We found that the expression and phosphorylation of Smad1 are increased during the activation of HSCs. Moreover, TGF-β significantly inhibits Smad1 gene expression in HSCs in a time- and dose-dependent manner. Furthermore, although both TGF-β1 and BMP2 stimulate the activation of HSCs, they have different effects on HSC proliferation. In conclusion, Smad1 expression and phosphorylation are increased during the activation of HSCs and TGF-β1 significantly inhibits the expression of the Smad1 gene.
Deficit in nitric oxide production in cirrhotic rat livers is located in the sinusoidal and postsinusoidal areas
Authors: Loureiro-Silva Mauricio R. , Cadelina Gregory W. , Groszmann Roberto J.
Published: March 2015

Intrahepatic nitric oxide (NO) production is decreased in cirrhotic livers. Our objective was to identify, in cirrhotic rat livers, intrahepatic vascular segments where the deficit of NO facilitates the effect of vasoconstrictors. By using a modified rat liver perfusion system with measurement of both the perfusion and sinusoidal (wedged hepatic vein) pressures, we studied the effect of the NO synthase blocker Nω-nitro-l-arginine (l-NNA) on the response to methoxamine (α1-adrenoreceptor agonist) in different segments of the intrahepatic circulation of normal and cirrhotic rat livers.l-NNA enhanced the presinusoidal, sinusoidal, and postsinusoidal responses to methoxamine in normal livers as well as the presinusoidal response in cirrhotic livers. However, l-NNA did not change the already enhanced sinusoidal/postsinusoidal response to methoxamine in cirrhotic livers. The postsinusoidal response to methoxamine was higher in cirrhotic rats with ascites than in those without ascites. We concluded that NO modulates the presinusoidal, sinusoidal, and postsinusoidal vascular tone in normal livers. NO production in cirrhotic rat livers is severely impaired in the sinusoidal and postsinusoidal areas but is preserved in the presinusoidal area, as evidenced by its normal response tol-NNA. We speculate that an increased postsinusoidal response to catecholamines may participate in the genesis of ascites in cirrhosis.
Mechanisms of hypothermic protection against ischemic liver injury in mice
Authors: Kato Atsushi , Singh Saurabh , McLeish Kenneth R. , Edwards Michael J. , Lentsch Alex B.
Published: March 2015

Hepatic hypothermia can safely prolong the duration of hepatic inflow occlusion during complex liver resectional surgeries. The mechanism(s) by which hypothermia protects against this form of liver ischemia-reperfusion injury are not completely understood. In this study, we sought to determine whether hypothermia protects against ischemia-reperfusion injury by altering the hepatic inflammatory response. Mice undergoing 90 min of partial hepatic ischemia followed by up to 8 h of reperfusion had their body temperatures regulated at 35–37°C (normothermic) or unregulated, in which rectal temperature dropped as low as 25°C by the end of ischemia (hypothermic). Hypothermic mice had less liver injury vs. normothermic mice, as assessed histologically, by serum transaminase levels (89% decrease), and by liver wet-to-dry weight ratios (91% decrease). Neutrophil accumulation was absent in hypothermic mice (99% reduction vs. normothermic mice). Production of the proinflammatory cytokines tumor necrosis factor-α, interleukin-1β, and macrophage inflammatory protein-2 were reduced by up to 92%. Activation of the transcription factor nuclear factor-κB was not reduced in hypothermic mice, but activation of c-Jun NH2-terminal kinase (JNK) and the transcription factor activator protein (AP)-1 were greatly diminished. These data suggest that hypothermia suppresses the hepatic inflammatory response through selective inhibition of JNK and AP-1.
Peptide fragments of AMP-18, a novel secreted gastric antrum mucosal protein, are mitogenic and motogenic
Authors: Toback F. Gary , Walsh-Reitz Margaret M. , Musch Mark W. , Chang Eugene B. , Del Valle John , Ren Hongyu , Huang Erick , Martin Terence E.
Published: March 2015

Antrum mucosal protein (AMP)-18 is a novel 18-kDa protein synthesized by cells of the gastric antrum mucosa. The protein is present in secretion granules of murine gastric antrum epithelial cells and is a component of canine antrum mucus, suggesting that it is secreted into the viscoelastic gel layer on the mucosal surface. Release of the protein appears to be regulated because forskolin decreased the amount of immunoreactive AMP-18 in primary cultures of canine antrum mucosal epithelial cells, and indomethacin gavaged into the stomach of mice reduced AMP-18 content in antrum mucosal tissue before inducing histological injury. A functional domain of the protein was identified by preparing peptides derived from the center of human AMP-18. A 21-mer peptide stimulated growth of gastric and intestinal epithelial cells, but not fibroblasts, and increased restitution of scrape-wounded gastric epithelial monolayers. These functions of AMP-18 suggest that its release onto the apical cell surface is regulated and that the protein and/or peptide fragments may protect the antral mucosa and promote healing by facilitating restitution and proliferation after injury.
Alterations of the VIP-stimulated cAMP pathway in rat distal colon after abdominal irradiation
Authors: Morel E. , Dublineau I. , Lebrun F. , Griffiths N. M.
Published: March 2015

Ionizing radiation induces hyporesponsiveness of rat colonic mucosa to vasoactive intestinal peptide (VIP). Possible mechanisms responsible for this hyporesponsiveness of the cAMP communication pathway in rat colon were investigated. VIP- and forskolin-stimulated short-circuit current ( Isc) responses were studied after a 10-Gy abdominal irradiation in Ussing chambers as well as in single, isolated crypts. Adenylyl cyclase (AC) activity and VIP receptor characteristics were determined in mucosal membrane preparations. In addition, alterations in crypt morphology were studied. Impaired secretory responses to VIP and forskolin were observed 4 days after irradiation (decrease of 80%). cAMP analog-stimulated Iscresponses were unchanged. In isolated crypts, VIP- and forskolin-stimulated cAMP accumulation was markedly reduced by 80 and 50%, respectively. VIP-stimulated AC activity and VIP receptor number were decreased in membrane preparations. No major change of cellularity was associated with these functional alterations. In conclusion, the decreased secretory responses to VIP of rat colon are associated with reduced cAMP accumulation, decreased AC activity, and diminution of VIP receptor numbers without a marked decrease of crypt cell number.
mRNA localization in polarized intestinal epithelial cells
Authors: Houle Vicki M. , Li Wei , Montgomery Robert K. , Grand Richard J.
Published: March 2015

An important feature of enterocyte maturation is the asymmetrical distribution of cellular functions including protein localization. mRNA sorting is one mechanism for establishment and maintenance of this process in other systems, and we have previously demonstrated differential localization of mRNAs in human enterocytes. To study regulation of mRNA sorting, we established a model in polarized Caco-2 cells. Proxy cDNA constructs containing β-galactosidase (β-gal)/green fluorescence protein (GFP) and the 3′-untranslated region (3′-UTR) of either human sucrase-isomaltase or villin were transfected transiently or stably. A control construct contained poly-A sequence in place of 3′-UTR. Expression of GFP was observed by confocal microscopy; intracellular location of the construct mRNA was imaged by in situ hybridization. The sucrase-isomaltase mRNA proxy localized to an apical position in Caco-2 cells as in native enterocytes; the villin mRNA proxy did not show significant localization. The control construct was not localized and was found diffusely throughout the cell. Proxy GFP proteins tended to localize with their mRNA proxies, but with less precision. This study establishes a valuable model for the investigation of mRNA localization in intestinal epithelial cells. Mechanisms controlling asymmetrical distribution of intestinal mRNAs can be now be elucidated.
Amelioration of TNBS-induced colon inflammation in rats by phospholipase A2 inhibitor
Authors: Krimsky M. , Yedgar S. , Aptekar L. , Schwob O. , Goshen G. , Gruzman A. , Sasson S. , Ligumsky M.
Published: March 2015

The pathophysiology of inflammatory bowel disease (IBD) involves the production of diverse lipid mediators, namely eicosanoids, lysophospholipids, and platelet-activating factor, in which phospholipase A2 (PLA2) is the key enzyme. Accordingly, it has been postulated that control of lipid mediator production by inhibition of PLA2 would be useful for the treatment of IBD. This hypothesis was tested in the present study by examining the therapeutic effect of a novel extracellular PLA2 inhibitor (ExPLI), composed of carboxymethylcellulose-linked phosphatidylethanolamine (CMPE), on trinitrobenzenesulfonic acid-induced colitis. Intraperitoneal administration of CMPE suppressed the colitis as measured by mortality rate, intestinal permeability, plasma PLA2 activity, intestinal myeloperoxidase activity, and histological morphometry. Current therapeutic approaches for inflammatory conditions focus on the selective control of a lipid mediator(s) (e.g., prostaglandins or leukotrienes). The present study supports the concept that inclusive control of lipid mediator production by PLA2 inhibition is a plausible approach to the treatment of colitis and introduces the ExPLIs as a prototype of a novel NSAID for the treatment of intestinal inflammation.
Ammonia-induced apoptosis is accelerated at higher pH in gastric surface mucous cells
Authors: Suzuki Hideo , Yanaka Akinori , Shibahara Takeshi , Matsui Hirofumi , Nakahara Akira , Tanaka Naomi , Muto Hiroshi , Momoi Takashi , Uchiyama Yasuo
Published: March 2015

Gastric luminal ammonia produced by Helicobacter pylori has been shown to cause gastric mucosal injury. This study was conducted to examine the mechanisms by which gastric luminal ammonia causes apoptosis of gastric epithelial cells. Monolayers of GSM06 cells, developed from murine gastric surface mucous cells, were cultured in the absence or presence of 10–30 mM NH4Cl at ambient pH of 5.0, 6.0, and 7.0. In the presence of luminal NH4Cl, GSM06 cells showed 1) cell shrinkage and nuclear chromatin condensation, 2) DNA fragmentation into oligonucleosomes, 3) leakage of cytochrome c into cytosolic fraction without affecting bax expression, and 4) increases in activity of caspases-3 and -9. These changes were accentuated when the cells were cultured at pH 7.0. In the absence of NH4Cl, none of these changes was detected at any pH examined. These results suggest that gastric luminal ammonia, at concentrations detected in H. pylori-infected subjects, induces apoptosis of gastric epithelial cells by release of cytochrome c from mitochondria, followed by activation of caspases-9 and -3, especially at higher ambient pH.
Toxin B ofClostridium difficileactivates human VIP submucosal neurons, in part via an IL-1β-dependent pathway
Authors: Neunlist M. , Barouk J. , Michel K. , Just I. , Oreshkova T. , Schemann M. , Galmiche J. P.
Published: March 2015

This study investigated whether toxin B of Clostridium difficile can activate human submucosal neurons and the involved pathways. Isolated segments of human colon were placed in organ culture for 3 h in the presence of toxin B or IL-1β. Whole mounts of internal submucosal plexus were stained with antibodies against c-Fos, neuron-specific enolase (NSE), vasoactive intestinal polypeptide (VIP), and substance P (SP). The membrane potential (Vm) response of submucosal neurons to local application of toxin B and IL-1β was determined by a multisite optical recording technique. Toxin B (0.1 to 10 ng/ml) increased the proportion of c-Fos-positive neurons dose dependently compared with the control. In the presence of toxin B (10 ng/ml), most c-Fos-positive neurons were immunoreactive for VIP (79.8 ± 22.5%) but only 19.4 ± 14.0% for SP. Toxin B induced a rapid rise in IL-1β mRNA level and a sixfold increase in IL-1β protein in supernatant after 3 h of incubation. c-Fos expression induced by toxin B was reduced dose dependently by IL-1 receptor antagonist (0.1-10 ng/ml). IL-1β significantly increased c-Fos expression in submucosal neurons compared with the control (34.2 ± 10.1 vs. 5.1 ± 1.3% of NSE neurons). Microejection of toxin B had no effect on the Vmof enteric neurons. Evidence of a direct excitatory effect of IL-1β on Vmwas detected in a minority of enteric neurons. Therefore, toxin B of C. difficile activates VIP-positive submucosal neurons, at least in part, via an indirect IL-1β-dependent pathway.
Multimodal assessment of pain in the esophagus: a new experimental model
Authors: Drewes Asbjørn Mohr , Schipper Klaus-Peter , Dimcevski Georg , Petersen Poul , Andersen Ole Kæseler , Gregersen Hans , Arendt-Nielsen Lars
Published: March 2015

A new multimodal pain assessment model was developed integrating electrical, mechanical, cold, and warmth stimuli into the same device. The device, with a bag and electrodes for electrical stimulation, was positioned in the lower part of the esophagus in 11 healthy subjects. Mechanical stimuli were delivered with an impedance planimetric system. Thermal stimuli were performed by circulating water of different temperatures (5–50°C) inside the bag. All subjects reported both nonpainful and painful local and referred sensations to all stimuli. Temporal summation to repeated electrical stimuli could be studied. For all stimuli, there was a relationship between stimulus intensity and pain intensity. The referred pain area increased with increasing intensity of the electrical and mechanical stimuli. There were several differences between the sensations evoked by the four stimulus modalities, indicating activation of different visceral nerve pathways. This model offers the possibility for controlled multimodal stimuli activating the superficial and deeper layers of the human gut and should be used in basic, clinical, and pharmacological pain studies.
Proapoptotic protein PACT is expressed at high levels in colonic epithelial cells in mice
Authors: Gupta Vishal , Patel Rekha C.
Published: March 2015

The protein activator of RNA-activated protein kinase (PKR) is a proapoptotic protein called PACT. PKR is an interferon (IFN)-induced serine-threonine protein kinase that plays a central role in IFN's antiviral and antiproliferative activities. PKR activation in cells leads to phosphorylation of the α-subunit of the eukaryotic protein synthesis initiation factor (eIF)2α, inhibition of protein synthesis, and apoptosis. In the absence of viral infections, PKR is activated by its activator PACT, especially in response to diverse stress signals. Overexpression of PACT in cells causes enhanced sensitivity to stress-induced apoptosis. We examined PACT expression in different mouse tissues and evaluated its possible role in regulating apoptosis. PACT is expressed at high levels in colonic epithelial cells, especially as they exit the cell cycle and enter an apoptotic program. PACT expression also coincides with the presence of active PKR and phosphorylated eIF2α. These results suggest a possible role of PACT-mediated PKR activation in the regulation of epithelial cell apoptosis in mouse colon. In addition, transient overexpression of PACT in a nontransformed intestinal epithelial cell line leads to induction of apoptosis, further supporting PACT's role in inducing apoptosis.
Effect of intragastric barostat bag on proximal and distal gastric accommodation in response to liquid meal
Authors: Mundt M. W. , Hausken T. , Samsom M.
Published: March 2015

The barostat is the gold standard for measurement of proximal gastric accommodation. Ultrasonography can be used to measure gastric volume. The aim was to investigate the effects of the barostat bag on gastric accommodation and transpyloric flow. Accommodation after a liquid meal (300 ml, 450 kcal) was measured twice at random in eight healthy volunteers. Proximal accommodation was measured once using barostat and once using ultrasound (US). Antrum accommodation was measured using US. Bag volume (BV), antral area (AA), proximal gastric area, and proximal gastric diameter (PGD) data were assessed before and 1, 5, 15, 30, 40, 50, and 60 min postprandially. Transpyloric flow was measured using Doppler 1–5 min postprandially. Fasted, AA size was not affected by the barostat bag (1 mmHg > minimal distension pressure; 2.7 ± 0.5 vs. 2.6 ± 0.3 cm2). Postprandially, AAs were larger with the bag present (ANOVA, P < 0.04). Maximum AA was reached with the bag in 5 min, without the bag in 1 min postprandially (15.1 ± 2.3 vs. 9.4 ± 1.5 cm2; P < 0.03). Furthermore, AAs were related to BVs ( r = 0.57; P < 0.01). After bag deflation, AA decreased (11.9 ± 1.8 to 7.0 ± 0.9 cm2; P = 0.02) and was comparable with the 60-min AA size without the bag (7.1 ± 1.2 cm2; P = 0.76) present. Proximal gastric radius calculated from the BVs and PGDs was larger with the bag present (ANOVA, P < 0.001). No effect on early gastric emptying was observed. Postprandially, the barostat bag causes dilatation of the antrum due to meal displacement without influencing early gastric emptying. This antral dilatation is likely to induce exaggerated proximal gastric relaxation observed in studies using the barostat to evaluate fundic accommodation.
Expression of calcium-sensing receptor in rat colonic epithelium: evidence for modulation of fluid secretion
Authors: Cheng Sam X. , Okuda Masahiro , Hall Amy E. , Geibel John P. , Hebert Steven C.
Published: March 2015

The calcium-sensing receptor (CaSR) is activated by extracellular calcium (Ca[Formula: see text]) and mediates many of the known effects of extracellular divalent minerals on body cells. Both surface and crypt cells express CaSR transcripts and protein on both apical and basolateral surfaces. Raising Ca[Formula: see text] elicited increases in intracellular calcium (Ca[Formula: see text]) in both surface and crypt cells with an EC50 of 2 mM. The Ca[Formula: see text]-induced increase in Ca[Formula: see text] was associated with increases in inositol 1,4,5-trisphosphate and eliminated by U-73129, an inhibitor of phosphatidylinositol-phospholipase C, as well as by thapsigargin. Other CaSR agonists, Gd3+ and neomycin, mimicked these Ca[Formula: see text]-induced responses. Both luminal and bath Ca[Formula: see text], Gd3+, and neomycin induced increases in Ca[Formula: see text] in isolated perfused crypts. The stimulatory effect of forskolin on net fluid secretion in perfused crypts was abolished by increasing Ca[Formula: see text] in either luminal or bath perfusates. Thus both apical and basolateral CaSR on crypt cells are functional and provide pathways modulating net intestinal fluid transport that may have important implications for the prevention and treatment of certain diarrheal diseases associated with elevated cAMP.
TLR5-mediated activation of p38 MAPK regulates epithelial IL-8 expression via posttranscriptional mechanism
Authors: Yu Yimin , Zeng Hui , Lyons Sean , Carlson Adam , Merlin Didier , Neish Andrew S. , Gewirtz Andrew T.
Published: March 2015

Toll-like receptors (TLRs) activate antimicrobial gene expression in response to detection of specific bacterial products. Relatively little is known about TLR5, the only TLR thought to be preferentially expressed by epithelial cells, beyond that it confers activation of the transcription factor NF-κB in a MyD-88 dependent manner in response to flagellin. Because TLRs, in general, are also thought to signal through members of the MAPK family, we examined flagellin-induced MAPK activation (via examining its phosphorylation status) and its subsequent role in expression of the chemokine IL-8 in polarized intestinal epithelia. Flagellin, like other proinflammatory stimuli (TNF-α, Salmonella typhimurium), activated p38 MAPK in a TLR5-dependent manner, whereas aflagellate bacteria or EGF did not activate this kinase. Although ERK1 and -2 were also observed to be activated in response to flagellin, their activation was not restricted to proinflammatory stimuli because they were also potently activated by aflagellate bacteria ( S. typhimurium or Escherichia coli) and EGF (neither of which activate NF-κB in these cells). Pharmacological inhibition of p38 MAPK (by SB-203580) potently (IC50= 10 nM) reduced expression of IL-8 protein (maximal inhibition, 75%) but had no effect on NF-κB activation, only slightly attenuated upregulation of IL-8 mRNA levels in response to flagellin, and did not effect IL-8 mRNA stability. Together, these results indicate that epithelial TLR5 mediates p38 activation and subsequently regulates flagellin-induced IL-8 expression independently of NF-κB, probably by influencing IL-8 mRNA translation.
Structural differences in the enteric neural network in murine colon: impact on electrophysiology
Authors: Sibaev Andrei , Franck Hartmut , Vanderwinden Jean-Marie , Allescher Hans-Dieter , Storr Martin
Published: March 2015

The enteric neural network in the proximal murine colon shows a regularly occurring hypoganglionic region, which is here characterized by using anatomical and electrophysiological techniques. Staining with NADPH diaphorase, methylene blue, and cuprolinic blue in standard whole mounts and three-dimensional gut preparations of the murine proximal colon consistently revealed two hypoganglionic areas surrounded by a dense clustering of enteric neurons. This irregularity in the ganglionic plexus was found to be present in mice of three different genetic backgrounds, as well as in rats. The lack of myenteric ganglia in these regions was associated with an absence of the longitudinal muscle layer, as shown in cross sections. Histochemical identification of interstitial cells of Cajal in KitW-lacZ/+transgenic mice showed Kit-positive cells oriented parallel to both muscle layers of the colon. Kit-positive cells oriented parallel to the longitudinal muscle layers were absent in the hypoganglionic area described. Electrical field stimulation elicited TTX-sensitive inhibitory junction potentials (IJPs), which showed region-specific characteristics. The initial partly apamin-sensitive hyperpolarization was present in all parts of the murine colon, whereas a second sustained NG-nitro-l-arginine-sensitive hyperpolarization was absent in the cecum and decreased from the proximal to the distal colon. Dissecting the hypoganglionic area from the surrounding tissue abolished the otherwise normal inhibitory neurotransmission to the circular muscle (1.6 ± 1.4 and 2.6 ± 1.7 mV for the fast and slow component of IJP amplitude in the hypoganglionic area vs. 16.5 ± 1.9 and 23.7 ± 2.7 mV for the fast and slow component of IJP amplitude in the neuron-rich area, respectively, P < 0.01, n = 6), whereas dissection of an area of identical size with an intact myenteric network showed normal inhibitory neurotransmission, indicating that the hypoganglionic area receives essential functional neural input from the neuron-rich surrounding tissue. In summary, in the murine and rat proximal colon, a constant and distinct hypoganglionic region is described with important concomitant changes in local electrophysiology.
Effects of fat digestion on appetite, APD motility, and gut hormones in response to duodenal fat infusion in humans
Authors: Feinle Christine , O'Donovan Deirdre , Doran Selena , Andrews Jane M. , Wishart Judith , Chapman Ian , Horowitz Michael
Published: March 2015

The presence of nutrients in the small intestine slows gastric emptying and suppresses appetite and food intake; these effects are partly mediated by the release of gut hormones, including CCK. We investigated the hypothesis that the modulation of antropyloroduodenal motility, suppression of appetite, and stimulation of CCK and glucagon-like peptide-1 secretion by intraduodenal fat are dependent on triglyceride hydrolysis by lipase. Sixteen healthy, young, lean men were studied twice in double-blind, randomized, crossover fashion. Ratings for appetite-related sensations, antropyloroduodenal motility, and plasma CCK and glucagon-like peptide-1 concentrations were measured during a 120-min duodenal infusion of a triglyceride emulsion (2.8 kcal/min) on one day with, on the other day without, 120 mg tetrahydrolipstatin, a potent lipase inhibitor. Immediately after the duodenal fat infusion, food intake at a buffet lunch was quantified. Lipase inhibition with tetrahydrolipstatin was associated with reductions in tonic and phasic pyloric pressures, increased numbers of isolated antral and duodenal pressure waves, and stimulation of antropyloroduodenal pressure-wave sequences (all P < 0.05). Scores for prospective consumption and food intake at lunch were greater, and nausea scores were slightly less, and the rises in plasma CCK and glucagon-like peptide-1 were abolished (all P < 0.05). In conclusion, lipase inhibition attenuates the effects of duodenal fat on antropyloroduodenal motility, appetite, and CCK and glucagon-like peptide-1 secretion.
Role of NF-κB on liver cold ischemia-reperfusion injury
Authors: Takahashi Yoshihito , Ganster Raymond W. , Gambotto Andrea , Shao Lifang , Kaizu Takashi , Wu Tong , Yagnik Gautam P. , Nakao Atsunori , Tsoulfas George , Ishikawa Takashi , Okuda Toyokazu , Geller David A. , Murase Noriko
Published: March 2015

The role of NF-κB, the rapid-response transcription factor for multiple genes, in cold ischemia-reperfusion (I/R) injury was examined after syngeneic transplantation of liver grafts. Lewis rat recipients were killed 1–48 h after reperfusion of three different liver grafts: 1) uninfected control, 2) infected ex vivo with control adenoviral vector (AdEGFP), and 3) infected ex vivo with AdIκB. In uninfected control livers, NF-κB was activated biphasically at 1–3 and 12 h after reperfusion with aspartate transaminase (AST) levels of 4,244 ± 691 IU/l. The first peak of NF-κB activation associated with an increase of mRNA for TNF-α, IL-1β, and IL-10. AdEGFP transfection resulted in similar outcomes. Interestingly, AdIκB-transfected liver grafts suffered more severe I/R injury (AST >9,000 IU/l). Transfected IκB was detected in transplanted livers as early as 6 h, and this correlated with the abrogation of the second, but not the first, peak of NF-κB activation at 12–48 h and increased apoptosis. Thus inhibition of the second wave of NF-κB activation in IκB-transfected livers resulted in an increase of liver injury, suggesting that NF-κB may have a dual role during liver I/R injury.
Central and noncentral blood volumes in cirrhosis: relationship to anthropometrics and gender
Authors: Møller Søren , Henriksen Jens H. , Bendtsen Flemming
Published: March 2015

The size of the central and arterial blood volume (CBV) is essential in the understanding of fluid retention in cirrhosis. Previously, it has been reported decreased, normal, or increased, but no reports have analyzed CBV with respect to gender and lean body mass. The aim of the present study was by means of an optimized technique to reassess it in a large group of patients with cirrhosis compared with healthy controls and matched controls in relationship to their body dimensions and gender. Eighty-three patients with cirrhosis (male/female, 60:23), 67 patients without liver disease (male/female, 22:45), and 14 young healthy controls (male/female, 6:8) underwent a hemodynamic investigation with determination of cardiac output, central circulation time, and CBV determined according to kinetic principles. Related to gender, CBV was lower in male cirrhotics (1.48 ± 0.30 liter) than in matched and young controls (1.68 ± 0.33 and 1.72 ± 0.33 liter, respectively; P < 0.05–0.01). No significant differences in CBV were seen between female cirrhotics and controls. Absolute and adjusted CBVs were lower in the females than in men with cirrhosis ( P < 0.001), and men with cirrhosis had lower absolute and body weight-adjusted CBVs than matched controls ( P< 0.01). Normalized values of CBV (%total blood volume) were significantly lower in patients with cirrhosis (25 ± 4%) than in matched controls (31 ± 7%) and young controls (28 ± 4%; P < 0.02). CBV correlated significantly with anthropometrics, including lean body mass ( r = 0.68–0.82; P < 0.0001). In conclusion, the CBV of patients with cirrhosis was lower than that of controls when adjusted for body dimensions and gender. There are significant gender differences, and signs of underfilling are more pronounced in male than in female patients. The results emphasize the importance of adjustments of blood volumes for anthropometrics and gender.
Embolization by sinusoidal lining cells obstructs the microcirculation in rat sinusoidal obstruction syndrome
Authors: DeLeve Laurie D. , Ito Yoshiya , Bethea Nancy W. , McCuskey Margaret K. , Wang Xiangdong , McCuskey Robert S.
Published: March 2015

Mechanisms leading to the obstruction of the microcirculation in sinusoidal obstruction syndrome (SOS) have been unclear. Because this occurs at the onset of disease, this is a potential key target for therapeutic intervention. Rats were treated with monocrotaline with or without continuous intraportal infusion of glutathione and were studied at 0.5, 1, 2, 4, 6, and 10 days after monocrotaline treatment with the use of in vivo microscopy and transmission electron microscopy. Sinusoidal perfusion decreased from days 1 through 10 with a nadir on day 4. At 12 h, numerous swollen sinusoidal endothelial cells (SECs) were observed. Subsequently, red blood cells penetrated into the space of Disse through gaps between and through swollen SEC and dissected the sinusoidal lining away from the parenchymal cells. Sinusoidal blood flow was obstructed by an embolism of aggregates of sinusoidal lining cells, red blood cells, and adherent monocytes. All changes were prevented by glutathione infusion, notably the initial swelling of SEC. SOS is initiated by changes in SEC. Microcirculatory obstruction is due to dissection of the sinusoidal lining, followed by embolization of the sinusoid by sinusoidal lining cells, compounded by aggregates of monocytes adherent in the sinusoids. Glutathione prevents SOS by preserving an intact sinusoidal barrier.
Simple and efficient method for isolation and cultivation of endoscopically obtained human colonocytes
Authors: Seidelin Jakob B. , Horn Thomas , Nielsen Ole H.
Published: March 2015

Few comparative and validated reports exist on the isolation and growth of colonoscopically obtained colonic epithelium. The aim of this study was to develop and validate a simple method for the cultivation of colonoscopically obtained colonocytes. Forty patients, who underwent routine colonoscopy and where the diagnosis of irritable bowel syndrome was later reached, were included. Seven colon biopsies were taken and incubated at varying time periods of 10-120 min and temperatures of 4-37°C in a chelating buffer. The epithelium was then harvested and cultivated under three different conditions: 1) on a collagen coating, 2) embedded in a collagen gel, or 3) embedded in a gel put on a porous well insert. The effect of conditioned medium (CM), insulin, transferrin, selenium, and the oxygen content was assessed. Viability was tested by the metabolic dimethylthiazol-diphenyl-tetrazolium bromide assay, by flowcytometry, by phase contrast microscopy, and by transmission electron microscopy. Incubation at 21°C for 75 min gave an optimal yield of 3 × 106 (2.0-3.8 × 106) viable epithelial cells in intact crypts per seven biopsies. Embedding of crypts in a collagen gel put on a porous membrane was superior to the other methods applied [ P < 0.003; median viability 71% (62-100%) compared with preculture values] after 24 h, which was a 160% increase in viability compared with coat-cultivated cells. CM had similar viability supporting effects to FCS. Other supplements had no effects. A simple method is presented, which makes cultivation of colonocytes obtained at endoscopy possible for up to 72 h.
Effects of bile acids on the muscle functions of guinea pig gallbladder
Authors: Xiao Zuo-Liang , Rho Aloysius K. , Biancani Piero , Behar Jose
Published: March 2015

Hydrophobic bile acids impair gallbladder emptying in vivo and inhibit gallbladder muscle contraction in response to CCK-8 in vitro. This study was aimed at determining the mechanisms of muscle cell dysfunction caused by bile acids in guinea pig gallbladders. Muscle cells were obtained by enzymatic digestion. Taurochenodeoxycholic acid (TCDC), a hydrophobic bile acid, caused a contraction of up to 15% and blocked CCK-induced contraction. Indomethacin abolished the TCDC-induced contraction. Hydrophilic bile acid tauroursodeoxycholic acid (TUDC) had no effect on muscle contraction but prevented the TCDC-induced contraction and its inhibition on CCK-induced contraction. Pretreatment with NADPH oxidase inhibitor Ph2I, xanthine oxidase inhibitor allopurinol, and free-radical scavenger catalase also prevented TCDC-induced contraction and its inhibition of the CCK-induced contraction. TCDC caused H2O2production, lipid peroxidation, and increased PGE2synthesis and activities of catalase and SOD. These changes were significantly inhibited by pretreatment of Ph2I or allopurinol. Inhibitors of cytosolic phospholipase A2(cPLA2), protein kinase C (PKC), and mitogen-activating protein kinase (MAPK) also blocked the TCDC-induced contraction. It is concluded that hydrophobic bile acids cause muscle cell dysfunction by stimulating the formation of H2O2via activation of NADPH and xanthine oxidase. H2O2causes lipid peroxidation and activates cPLA2to increase PGE2production, which, in turn, stimulates the synthesis of free-radical scavengers through the PKC-MAPK pathway.