bluuebunny/crossref_metadata_2025 huggingface dataset:
Dietary diosgenin attenuates subacute intestinal inflammation associated with indomethacin in rats
Authors: Yamada T. , Hoshino M. , Hayakawa T. , Ohhara H. , Yamada H. , Nakazawa T. , Inagaki T. , Iida M. , Ogasawara T. , Uchida A. , Hasegawa C. , Murasaki G. , Miyaji M. , Hirata A. , Takeuchi T.
Published: December 2017

We investigated the effects of dietary diosgenin (Dio), a plant-derived sapogenin, on indomethacin (Indo)-induced intestinal inflammation and alterations in bile secretion in rats. In anesthetized rats, bile secretion, intestinal inflammation, and blood chemistry were assessed 3 days after two subcutaneous injections of Indo given 24 h apart. Dio (> 80 mg.kg-1.day-1) pretreatment significantly inhibited weight and food intake decreases and intestinal inflammation. This protective effect was confirmed by examination of gross and histological findings and intestinal myeloperoxidase activity. Dio significantly increased biliary cholesterol (Chol) output and prevented the decreases in bile flow, bile acid output, and biliary alpha-muricholic acid and the increases in biliary hyodeoxycholic acid, deoxycholic acid, and hydrophobicity index of bile. Significantly more biliary Chol and phospholipids were present in macromolecules separate from bile acids and Indo in Dio-treated rats. Dio significantly increased the elimination constant of Indo and reduced plasma Indo levels at 3 and 12 h but did not influence biliary secretion of Indo for 3.5 h after injection. Although Dio dose-dependently attenuated subacute intestinal inflammation and normalized bile secretion in this model, it may also compromise the anti-inflammatory action of indo.
Inhibition of nitric oxide synthesis improves detoxication in inflammatory liver dysfunction in vivo
Authors: Veihelmann A. , Brill T. , Blobner M. , Scheller I. , Mayer B. , Prolls M. , Himpel S. , Stadler J.
Published: December 2017

Inflammatory stimulation of the liver induces nitric oxide (NO) biosynthesis and suppression of detoxication. In this study the effect of NO biosynthesis on cytochrome P-450 (CYP) enzyme activity was investigated by comparing in vivo and in vitro assays. To establish liver inflammation, CD rats were injected with Corynebacterium parvum (C. parvum) suspension. After 5 days NO biosynthesis was highly induced as indicated by increased NO2- plus NO3- serum concentrations. At the same time the aminopyrine breath test (ABT), measuring CYP activity in vivo, was reduced to 42% and the in vitro assay of aminopyrine turnover was suppressed to 12% of NaCl- injected controls. When C. parvum-injected animals were treated with the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA), CYP activities significantly improved with an ABT of 76% and an in vitro aminopyrine turnover of 47% of controls. Neither C. parvum injections nor L-NMMA treatment resulted in a significant change of CYP protein concentrations. These data indicate that suppression of xenobiotic metabolism can be attenuated by inhibition of NO biosynthesis during an ongoing process of inflammation.
I. Neutrophil adhesive interactions with intestinal epithelium
Authors: Parkos Charles A.
Published: December 2017

In many inflammatory conditions of the gastrointestinal tract, disease activity and patient symptoms correlate with the histological finding of neutrophil (PMN) migration across the epithelium. PMN interactions with intestinal epithelium can influence epithelial functions ranging from barrier maintenance to electrolyte secretion. Additionally, PMN recruitment to the epithelium can be modulated by epithelial interactions with luminal enteric pathogens. Adhesive interactions between PMN and intestinal epithelial cells have been shown to be distinct from interactions of PMN with endothelia. In particular, PMN transepithelial migration is modulated by a distinct array of cytokines including interferon-γ and interleukin-4 and requires the PMN β2-integrin CD11b/CD18 but is independent of CD11a/CD18, selectins, and intercellular adhesion molecule 1. Additionally, an integral membrane protein termed CD47 has recently been shown to play an important role in PMN transepithelial migration at point(s) subsequent to initial adhesive interactions. This article provides a brief overview of PMN interactions with epithelia and their functional consequences in relation to inflammatory disease.
Characterization of the pharyngo-UES contractile reflex in humans
Authors: Shaker Reza , Ren Junlong , Xie Pengyan , Lang Ivan M. , Bardan Eytan , Sui Zhumei
Published: December 2017

Preliminary human studies suggest the presence of an upper esophageal sphincter (UES) contractile reflex triggered by pharyngeal water stimulation. The purposes of this study were to further characterize this reflex and determine the threshold volume for its activation. We studied 10 healthy young volunteers by manometric technique before and after topical pharyngeal anesthesia. UES pressure responses to various volumes and temperatures of water injected into the pharynx were elucidated. At a threshold volume, rapid-pulse and slow continuous pharyngeal water injection resulted in significant augmentation of UES pressure in all volunteers. Threshold volume for inducing UES contraction averaged 0.1 ± 0.01 ml for rapid-pulse injection and was significantly smaller than that for slow continuous injection (1.0 ± 0.2 ml). UES pressure increase duration averaged 16 ± 4 s. Augmentation of UES resting tone by injection of water with three different temperatures was similar. This augmentation was abolished after topical anesthesia. Conclusions were that stimulation of the human pharynx by injection of minute amounts of water results in a significant increase in resting UES pressure: the pharyngo-UES contractile reflex. The magnitude of pressure increase due to activation of this reflex is not volume or temperature dependent. Loss of pharyngeal sensation abolishes this reflex.
Molecular mechanisms for the growth factor action of gastrin
Authors: Todisco Andrea , Takeuchi Yoshiaki , Urumov Andrej , Yamada Junko , Stepan Vinzenz M. , Yamada Tadataka
Published: December 2017

We have previously observed that gastrin has a cholecystokinin B (CCK-B) receptor-mediated growth-promoting effect on the AR42J rat pancreatic acinar cell line and that this effect is paralleled by induction of expression of the early response gene c- fos. We undertook these experiments to elucidate the mechanism for induction of c- fos and the linkage of this action to the trophic effects of gastrin. Gastrin (0.1–10 nM) dose dependently induced luciferase activity in AR42J cells transfected with a construct consisting of a luciferase reporter gene coupled to the serum response element (SRE) of the c- fos promoter. This effect was blocked by the specific CCK-B receptor antagonist D2 but not by the specific CCK-A receptor antagonist L-364,718 or by pertussis toxin, indicating that gastrin targets the SRE via specific CCK-B receptors through a mechanism independent of Gi. Inhibition of protein kinase C (PKC) either by prolonged (24 h) exposure of the cells to the phorbol ester 12- O-tetradecanoylphorbol 13-acetate (100 nM) or by incubation with the selective inhibitor GF-109203X (3.5 μM) resulted in an 80% reduction in luciferase activity. Similar results were observed in the presence of the specific extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor PD-98059 (50 μM). We measured ERK2 activity in AR42J cells via in-gel kinase assays and observed that gastrin (1 pM-100 nM) induced ERK2 enzyme activity in a dose-dependent manner. Addition of GF-109203X and PD-98059, either alone or in combination, produced, respectively, partial and total inhibition of gastrin-induced ERK2 activity. Gastrin induction of ERK2 activity also resulted in a threefold increase in the transcriptional activity of Elk-1, a factor known to bind to the c- fos SRE and to be phosphorylated and activated by ERK2. PD-98059 blocked the growth-promoting effect of gastrin on the AR42J cells, demonstrating that this effect depends on activation of MEK. Our data lead us to conclude that the trophic actions of gastrin are mediated by ERK2-induced c- fos gene expression via PKC-dependent and -independent pathways.
Acute experimental colitis decreases colonic circular smooth muscle contractility in rats
Authors: Myers Brian S. , Martin John S. , Dempsey Daniel T. , Parkman Henry P. , Thomas Rebecca M. , Ryan James P.
Published: December 2017

Distal colitis decreases the contractility of the underlying circular smooth muscle. We examined how time after injury and lesion severity contribute to the decreased contractility and how colitis alters the calcium-handling properties of the affected muscle. Distal colitis was induced in rats by intrarectal administration of 4% acetic acid. Contractile responses to acetylcholine, increased extracellular potassium, and the G protein activator NaF were determined for circular muscle strips from sham control and colitic rats at days 1, 2, 3, 7, and 14 postenemas. Acetylcholine stimulation of tissues from day 3colitic rats was performed in a zero calcium buffer, in the presence of nifedipine, and after depletion of intracellular stores of calcium. The colitis was graded macroscopically as mild, moderate, or severe. Regardless of agonist, maximal decrease in force developed 2 to 3 days posttreatment, followed by a gradual return to control by day 14. The inhibitory effect of colitis on contractility increased with increasing severity of inflammation. Limiting extracellular calcium influx had a greater inhibitory effect on tissues from colitic rats; intracellular calcium depletion had a greater inhibitory effect on tissues from control animals. The data suggest that both lesion severity and time after injury affect the contractile response of circular smooth muscle from the inflamed distal colon. Impaired utilization of intracellular calcium may contribute to the decreased contractility.
Glucose and glutamine provide similar proportions of energy to mucosal cells of rat small intestine
Authors: Fleming Sharon E. , Zambell Kirsten L. , Fitch Mark D.
Published: December 2017

The objectives of this study were to establish a reliable method for quantifying glycolytic flux in intestinal epithelial cells, to determine the proportion of energy provided to small intestine epithelial cells by glucose vs. glutamine, and to determine whether there was an energetic advantage to having both substrates present simultaneously. There was substantial retention of3H in alanine and lactate when [2-3H]glucose was used as tracer for quantifying glycolysis, and the magnitude of the3H retention was influenced by the presence of other substrates and metabolites. Detritiation was at least 99% complete, however, when [3-3H]glucose was used as tracer in this system and the tritium was recovered as3H2O. Glycolytic flux was six- to sevenfold higher in cells of the proximal than distal small intestine but was not significantly different for young adult (4 mo) vs. aged adult (24 mo) rats. Net ATP production from exogenous substrates was higher when both glucose and glutamine were present simultaneously than when either substrate was present alone, and glucose was calculated to provide 50–60% of the net ATP produced from these two substrates. Most of the energy produced from glucose was produced via the anaerobic metabolic pathways (78% for glucose alone, 95% with glucose and glutamine). Net energy production was calculated to be 10% lower in cells from aged animals than in those from young animals, since CO2production from these major substrates was lower in cells from aged animals.
Role of nitric oxide in gut ischemia-reperfusion-induced hepatic microvascular dysfunction
Authors: Horie Yoshinori , Wolf Robert , Granger D. Neil
Published: December 2017

The overall objective of this study was to assess the contribution of an altered bioavailability of nitric oxide (NO) to the leukocyte adhesion and hypoxic stress elicited in the liver by gut ischemia-reperfusion (I/R). The accumulation of leukocytes, number of nonperfused sinusoids (NPS), and NADH autofluorescence were monitored (by intravital microscopy) in mouse liver after 15 min of superior mesenteric artery occlusion and 60 min of reperfusion. Leukostasis, NPS, and NADH autofluorescence (indicating hypoxia) were all increased in the liver at 60 min after gut I/R. The NO synthase inhibitor N G-monomethyl-l-arginine (l-NMMA) exaggerated the liver leukostasis elicited by gut I/R, responses that were prevented by coadministration of l-arginine. The NO donor diethylenetriamine-NO (DETA-NO) andl-arginine were both effective in attenuating the gut I/R-induced leukostasis and increased NADH autofluorescence, whereas neither DETA nord-arginine exerted a protective action. These findings indicate that NO is an important determinant of the liver leukostasis, impaired sinusoidal perfusion, and tissue hypoxia elicited by gut I/R.
Enterohepatic circulation of scymnol sulfate in an elasmobranch, the little skate (Raja erinacea)
Authors: Fricker Gert , Wössner Ralph , Drewe Jürgen , Fricker Ruth , Boyer James L.
Published: December 2017

The sulfated bile alcohol scymnol sulfate (ScyS), 3α,7α,12α,24ξ,26,27-hexahydroxy-5β-cholestane-26(27)-sulfate, is the major bile salt in bile of an elasmobranch, the little skate. To investigate hepatic transport of bile alcohols in skate liver, [3H]ScyS and a potential precursor, 3α,7α,12α-trihydroxy-5β-cholestane (chtriol), were used as model compounds. Their transport into isolated hepatocytes was partially saturable, temperature sensitive, and Na+independent. The uptake of ScyS was inhibited by cholyltaurine, and uptake of cholyltaurine was inhibited by ScyS in a competitive manner. In contrast, uptake of chtriol was not inhibited by cholyltaurine, suggesting separate transport systems. ScyS and chtriol showed a choleretic effect in isolated perfused livers. When ScyS was added to the perfusate of isolated perfused livers, >25% was found in bile within 7 h. When chtriol was added to the perfusate, 10% of the dose was secreted into the bile mainly in the form of polar metabolites, whereas only nonmetabolized chtriol remained in the livers. The slow bile flow of 40–50 μl/h and the high recovery in the liver suggest that metabolism may be the rate-limiting step in the hepatic elimination of chtriol. The major metabolites secreted into bile were identified by mass spectrometry and chromatography as scymnol and ScyS. To study the enterohepatic circulation, [3H]ScyS or [3H]chtriol was administered into the duodenum of free-swimming skates, and bile was collected through exteriorized indwelling cannulas over a 4-day period. More than 90% of the radioactivity was recovered from bile, indicating that there was a highly effective absorption in the intestinal epithelium, as well as specific transport mechanisms for hepatic uptake and biliary secretion of these compounds. This is the first direct demonstration of an enterohepatic circulation for a bile alcohol sulfate in fish liver.
α1-Acid glycoprotein reduces local and remote injuries after intestinal ischemia in the rat
Authors: Williams Julian P. , Weiser Martin R. , Pechet Taine T. V. , Kobzik Les , Moore Francis D. , Hechtman Herbert B.
Published: December 2017

The aim of this study was to look at the role of α1-acid glycoprotein as a natural anti-inflammatory agent with particular respect to its antineutrophil and anticomplement activity. A recombinantly engineered form of sialyl Lewisx(sLex)-bearing α1-acid glycoprotein (sAGP) was administered intravenously to pentobarbital-anesthetized rats after 50 min of intestinal ischemia just before 4 h of reperfusion. A non-sLex-bearing form of AGP (nsAGP) was used as control. sAGP-treated animals had a 62% reduction ( P < 0.05) in remote lung injury, assessed by125I-albumin permeability, compared with those treated with nsAGP (permeability index of 3.61 ± 0.15 × 10−3and 5.18 ± 0.67 × 10−3, respectively). There was a reduction in pulmonary myeloperoxidase levels in sAGP-treated rats compared with nsAGP-treated rats. Complement-dependent intestinal injury, assessed by125I-albumin permeability was reduced by 28% ( P < 0.05) in animals treated with sAGP (7.58 ± 0.63) compared with those treated with nsAGP (10.4 ± 0.54). We conclude that sAGP ameliorates both complement- and neutrophil-mediated injuries.
Endothelial cell monolayers as a tool for studying microvascular pathophysiology
Authors: Kvietys Peter R. , Granger D. Neil
Published: December 2017

Endothelial cells contribute to a variety of biological responses that facilitate organ function. This critical role of the endothelial cell has resulted in the development of different in vitro models that utilize monolayers of cultured cells to simulate conditions that exist in the intact animal. This review focuses on endothelial cell monolayers as a model system for research on certain pathophysiological conditions affecting the gastrointestinal tract. The advantages and limitations of endothelial cell monolayers are addressed, along with evolving technologies and strategies that hold promise for extending the utility of this in vitro model for studies of gastrointestinal function and disease.
Adult human colonic subepithelial myofibroblasts express extracellular matrix proteins and cyclooxygenase-1 and -2
Authors: Mahida Y. R. , Beltinger J. , Makh S. , Göke M. , Gray T. , Podolsky D. K. , Hawkey C. J.
Published: December 2017

Interactions between epithelial cells and subepithelial myofibroblasts are increasingly recognized as important in the regulation of epithelial cell function. We have established primary cultures of subepithelial myofibroblasts from adult human colonic mucosal samples denuded of epithelial cells and maintained in culture. During culture of mucosal tissue, subepithelial myofibroblasts migrated out via basement membrane pores before establishment in culture. Despite prolonged culture and passage, the myofibroblasts maintained their phenotype, as demonstrated by expression of α-smooth muscle actin and vimentin. The cells expressed transcripts and protein for cyclooxygenase (COX)-1 and -2 enzymes, and their release of prostaglandin E2(PGE2) was inhibited by selective COX-1 and -2 inhibitors. The myofibroblasts also expressed the extracellular matrix (ECM) proteins collagen type IV, laminin-β1and -γ1, and fibronectin. Adult human colonic subepithelial myofibroblasts may influence epithelial cell function via products of COX-1 and -2 enzymes, such as PGE2and secreted ECM proteins.
IL-1β and IL-6 in mouse parotid acinar cells: characterization of synthesis, storage, and release
Authors: Tanda Naoko , Ohyama Hiroe , Yamakawa Midori , Ericsson Maria , Tsuji Takanori , McBride Jim , Elovic Aram , Wong David T. W. , Login Gary R.
Published: December 2017

Synthesis, storage, and secretion of the proinflammatory cytokine interleukin-1β (IL-1β) and the anti-inflammatory cytokine IL-6 have not been established in normal exocrine gland secretory cells. Parotid glands and isolated acinar cells prepared from BALB/c mice were homogenized for RNA isolation and reverse transcription-polymerase chain reaction (RT-PCR). IL-1β and IL-6 enzyme-linked immunosorbent assays (ELISAs) were done on supernatants prepared from mouse parotid acinar cell (MPAC) preparations unstimulated or stimulated between 0 and 10 min with 10−5M norepinephrine at 37°C. MPACs were fixed in paraformaldehyde, frozen sectioned for light and electron microscopy, and labeled with antibodies to IL-1β and IL-6. Mouse specific riboprobes to IL-1 and IL-6 were used for in situ hybridization. RT-PCR yielded the expected IL-1 (336-bp) and IL-6 (614-bp) mRNA products. By ELISA, stimulated MPACs showed a significant increase in IL-1β ( P < 0.03) and IL-6 ( P < 0.01) release into supernatants by 10 min that paralleled the time course of amylase release. In situ hybridization showed the presence of transcripts for IL-1 and IL-6 in glandular epithelial cells. Gold-labeled IL-1β and IL-6 were significantly higher ( P < 0.01) in granules than in the nucleus and cytoplasm. This study shows that MPACs synthesize IL-1β and IL-6 and release these cytokines from their granules after α- and β-adrenergic stimulation.
Expression and transport properties of the human ileal and renal sodium-dependent bile acid transporter
Authors: Craddock Ann L. , Love Martha W. , Daniel Rebecca W. , Kirby Lyndon C. , Walters Holly C. , Wong Melissa H. , Dawson Paul A.
Published: December 2017

The enterohepatic circulation of bile acids is maintained by Na+-dependent transport mechanisms. To better understand these processes, a full-length human ileal Na+-bile acid cotransporter cDNA was identified using rapid amplification of cDNA ends and genomic cloning techniques. Using Northern blot analysis to determine its tissue expression, we readily detected the ileal Na+-bile acid cotransporter mRNA in terminal ileum and kidney. Direct cloning and mapping of the transcriptional start sites confirmed that the kidney cDNA was identical to the ileal Na+-bile acid cotransporter. In transiently transfected COS cells, ileal Na+-bile acid cotransporter-mediated taurocholate uptake was strictly Na+dependent and chloride independent. Analysis of the substrate specificity in transfected COS or CHO cells showed that both conjugated and unconjugated bile acids are efficiently transported. When the inhibition constants for other potential substrates such as estrone-3-sulfate were determined, the ileal Na+-bile acid cotransporter exhibited a narrower substrate specificity than the related liver Na+-bile acid cotransporter. Whereas the multispecific liver Na+-bile acid cotransporter may participate in hepatic clearance of organic anion metabolites and xenobiotics, the ileal and renal Na+-bile acid cotransporter retains a narrow specificity for reclamation of bile acids.
Sex differences in multiple steps in hepatic transport of palmitate support a balanced uptake mechanism
Authors: Luxon B. A. , Holly D. C. , Milliano M. T. , Weisiger R. A.
Published: December 2017

Hepatic clearance of long-chain fatty acids is substantially faster in females than in males, a fact that may underlie known gender-related differences in lipoprotein metabolism and associated disease states. To further investigate the transport steps responsible for this difference, we used a novel method combining multiple-indicator dilution and steady-state measurements of palmitate extraction from albumin solutions. We found that cytoplasmic transport of palmitate is sufficiently slow (diffusion constants 9.0 and 5.9 × 10−9cm2/s for male and female liver, respectively) that the steady-state concentration of palmitate in the center of the cell should be ∼0.5 of that found in the cytoplasm just beneath the plasma membrane. Previous studies in cultured liver cells using nonphysiological fatty acids have shown more rapid cytoplasmic transport in females. This sex difference reflects higher concentrations of cytosolic fatty acid-binding protein, which acts as a carrier system to transport fatty acids across cell water layers. The current study confirmed slow cytoplasmic diffusion rates in intact perfused rat liver using a physiological fatty acid and found a similar female-to-male ratio. Female liver also had a greater influx rate constant and a larger vascular volume than male liver but had a similar rate of metabolism. Rapid cytoplasmic diffusion enhances movement of palmitate into deeper layers of the cell cytoplasm, thus reducing efflux. The larger sinusoidal volume in females not only permits more dissociation of palmitate from albumin within the sinusoids but also may generate a greater permeability-surface area product. These multiple sex-related differences combine to produce a nearly twofold greater steady-state uptake rate by female liver.
Stanniocalcin: a novel protein regulating calcium and phosphate transport across mammalian intestine
Authors: Madsen Karen L. , Tavernini Michele M. , Yachimec Christine , Mendrick Donna L. , Alfonso Pedro J. , Buergin Markus , Olsen Henrik S. , Antonaccio Micheal J. , Thomson Alan B. R. , Fedorak Richard N.
Published: December 2017

Stanniocalcin (STC) is an anti-hypercalcemic glycoprotein hormone previously identified in the corpuscles of Stannius in bony fish and recently in the human genome. This study undertook to express human STC in Chinese hamster ovary (CHO) cells and to determine its effects on calcium and phosphate absorption in swine and rat intestine. Unidirectional mucosal-to-serosal ( J m→s) and serosal-to-mucosal ( J s→m)45Ca and32P fluxes were measured in vitro in duodenal tissue in voltage-clamped Ussing chambers. Addition of STC (10–100 ng/ml) to the serosal surface of the duodenum resulted in a simultaneous increase in calcium J m→s and J s→mfluxes, with a subsequent reduction in net calcium absorption. This was coupled with an STC-stimulated increase in phosphate absorption. Intestinal conductance was increased at the highest dose of STC (100 ng/ml) in swine tissue. The addition of STC to the mucosal surface had no effect on calcium and phosphate fluxes. STC at doses of 10–1,000 ng/ml had no effect on short-circuit current in any region of the rat intestine. In conclusion, human recombinant STC decreases the absorption of calcium and stimulates the absorption of phosphate in both swine and rat duodenum. STC is a novel regulatory protein that regulates mammalian intestinal calcium and phosphate transport.
Characterization and regulation of adenosine transport in T84 intestinal epithelial cells
Authors: Mun Edward C. , Tally Kevin J. , Matthews Jeffrey B.
Published: December 2017

Adenosine release from mucosal sources during inflammation and ischemia activates intestinal epithelial Cl−secretion. Previous data suggest that A2breceptor-mediated Cl−secretory responses may be dampened by epithelial cell nucleoside scavenging. The present study utilizes isotopic flux analysis and nucleoside analog binding assays to directly characterize the nucleoside transport system of cultured T84 human intestinal epithelial cells and to explore whether adenosine transport is regulated by secretory agonists, metabolic inhibition, or phorbol ester. Uptake of adenosine across the apical membrane displayed characteristics of simple diffusion. Kinetic analysis of basolateral uptake revealed a Na+-independent, nitrobenzylthioinosine (NBTI)-sensitive facilitated-diffusion system with low affinity but high capacity for adenosine. NBTI binding studies indicated a single population of high-affinity binding sites basolaterally. Neither forskolin, 5′-( N-ethylcarboxamido)-adenosine, nor metabolic inhibition significantly altered adenosine transport. However, phorbol 12-myristate 13-acetate significantly reduced both adenosine transport and the number of specific NBTI binding sites, suggesting that transporter number may be decreased through activation of protein kinase C. This basolateral facilitated adenosine transporter may serve a conventional function in nucleoside salvage and a novel function as a regulator of adenosine-dependent Cl−secretory responses and hence diarrheal disorders.
Programmed cell death induced by ischemia-reperfusion in rat intestinal mucosa
Authors: Noda Takahiro , Iwakiri Ryuichi , Fujimoto Kazuma , Matsuo Shuzo , Aw Tak Yee
Published: December 2017

Apoptosis after ischemia-reperfusion (I/R) was characterized in rat small intestine. Under halothane anesthesia, the superior mesenteric artery in the rat was occluded for 15 or 60 min, followed by reperfusion. Ratios of fragmented DNA to total DNA, electrophoresis, and immunohistochemical staining were examined after I/R. Some rats were pretreated with α-difluoromethylornithine (DFMO) to examine the relationship between intestinal apoptosis and ornithine decarboxylase (ODC) activity. The percentage of fragmented DNA significantly increased just after ischemia and peaked at 1 h after reperfusion in the jejunum and ileum. These increases were significantly higher in the 60-min ischemia group compared with the 15-min ischemia group. This increase decreased 6 h after reperfusion. The results were corroborated by histological evaluations of the intestine under the same conditions. DFMO completely abolished elevation of ODC activity 6 h after reperfusion but did not change the percentage of fragmented DNA. Apoptosis in rat small intestine was induced by ischemia of the gut, and this process was exacerbated by reperfusion. The changes in apoptosis were independent of ODC activity.
Neurons in the vagal complex of the rat respond to mechanical and chemical stimulation of the GI tract
Authors: Zhang Xueguo , Renehan William E. , Fogel Ronald
Published: December 2017

Perfusing the duodenum with acid solutions dramatically reduces gastric motility and acid secretion. We propose that the presence of acid in the proximal small intestine initiates a vagovagal reflex that excites inhibitory neurons in the nucleus of the solitary tract (NST) and reduces the activity of the neurons in the dorsal motor nucleus of the vagus nerve (DMNV). However, results from several investigations suggest that the relevant circuit may not be as simple as we had believed. The present study was designed to address this dilemma by employing intracellular and extracellular recording and intracellular labeling techniques to provide direct information on the activity of neurons in the NST and DMNV during and after intestinal exposure to acid solutions. The results obtained prove that NST and DMNV neurons respond to HCl in the duodenum. In some instances, these neurons were very stimulus specific, although the majority of the cells in our sample (47% of NST neurons and 86% of DMNV neurons) also responded to distension of the stomach and/or duodenum. It is important to note, however, that many of the more broadly responsive neurons in the dorsal vagal complex were able to distinguish between mechanical and chemical stimulation of the gastrointestinal (GI) tract. Most of the NST neurons that responded to duodenal perfusion with HCl were excited by this stimulus. Conversely, activity of most of the DMNV neurons decreased after the onset of the HCl stimulus. These findings verify the existence of a vagovagal reflex pathway initiated by duodenal perfusion with acid. Presumably, this reflex would decrease gastric motility and acid secretion, reducing the amount of acid that enters the duodenum and ultimately protecting the intestinal mucosa.
Tonic and phasic motor activity in the proximal and distal colon of healthy humans
Authors: Jouet Pauline , Coffin Benoît , Lémann Marc , Gorbatchef Caroline , Franchisseur Claire , Jian Raymond , Rambaud Jean-Claude , Flourié Bernard
Published: December 2017

In healthy humans, meals stimulate phasic and tonic motor activity in the unprepared distal colon. The response of the proximal colon remains unknown. In this study, we assessed the effect of a liquid meal on proximal and distal colonic motor activity. In 12 healthy volunteers, colonic tone and phasic motility were simultaneously recorded by using an electronic barostat and perfused catheters in the fasting state and in response to a 1,000-kcal meal. The meal significantly increased the phasic activity in the distal colon (230 ± 46% of the basal value; P = 0.02) but not in the proximal colon (138 ± 25% of the basal value; P = 0.2). The intrabag volume of the barostat was significantly more reduced in the distal than in the proximal colon (74 ± 11 vs. 50 ± 9% of the basal values, respectively; P = 0.04). We conclude that the postprandial response of the unprepared proximal colon is an immediate tonic contraction that is less pronounced than in the distal colon.
Development of gastric slow waves in preterm infants measured by electrogastrography
Authors: Liang Jie , Co Edward , Zhang Ming , Pineda Josef , Chen J. D. Z.
Published: December 2017

The aim of this study was to investigate the developmental process of gastric myoelectrical activity (GMA) in preterm infants. Nineteen healthy preterm infants were studied. GMA was recorded using surface electrogastrography, and six follow-up studies were performed in each subject. Spectral analysis methods were applied to compute the parameters of the electrogastrogram (EGG). The results showed that there was a developmental process of GMA with age during the first 6 mo of life. 1) The percentage of normal slow waves showed a progressive increase after birth (36.7 ± 6.1, 37.8 ± 6.2, 47.0 ± 10.0, 52.2 ± 12.2, 55.2 ± 9.7, and 65.8 ± 13.5% at 1 and 2 wk and 1, 2, 4, and 6 mo, respectively); 2) there was a significant postprandial increase in the percentage of normal slow waves during the first 2 mo after birth; and 3) the percentages of normal slow waves for different gestation ages were not statistically significant. In conclusion, the percentage of normal slow waves is low at birth and there is a developmental process that may be stimulated by enteral feeding.
Cell volume regulates liver phosphoenolpyruvate carboxykinase and fructose-1,6-bisphosphatase genes
Authors: Kaiser Stephan
Published: December 2017

Hypertonic-induced cell shrinkage increases glucose release in H-4-II-E rat hepatoma cells. This is paralleled by a concomitant increase in the mRNA levels of the rate-limiting enzymes of the pathway of gluconeogenesis, phospho enolpyruvate carboxykinase (PCK) and fructose-1,6-bisphosphatase (FBP), of seven- and fivefold, respectively. In contrast, hypotonic-induced swelling of the cells results in a transient decrease in PCK and FBP mRNAs to 15% and 39% of control levels. The antagonistic effects of hyper- and hypotonicity mimic the counteracting effects of adenosine 3′,5′-cyclic monophosphate (cAMP) and insulin on PCK and FBP mRNA levels. The hypertonic-induced increase in mRNA levels is due to an enhanced transcriptional rate, whereas the decrease in mRNAs caused by hypotonicity results from a decrease in transcription as well as mRNA stability. The inductive effect of hypertonicity does not require ongoing protein synthesis and acts independently of the cAMP-dependent protein kinase and protein kinase C pathways. These results suggest that cell volume changes in liver cells may play an important role in regulating hepatic glucose metabolism by altered gene expression.
Rectal tone, distensibility, and perception: reproducibility and response to different distensions
Authors: Hammer H. F. , Phillips S. F. , Camilleri M. , Hanson R. B.
Published: December 2017

Increasing interest is focusing on the role of intestinal tone, distensibility, and mechanosensation in the genesis of abdominal symptoms. Experimental approaches usually feature balloon distension of the bowel with measurements of perception, tone, and compliance and/or elastance; however, the methodologies are standardized incompletely. We examined the reproducibility of repeated assessments of sensory perception, basal tone, and compliance and/or elastance of the rectum during distension. We also evaluated the response to inflations that varied in regard to control of pressure or volume, pattern of distension, and rate of inflation. Five healthy volunteers were studied under two separate protocols. The first featured a series of experiments on each of 5 days; the other consisted of 2 separate days of study. Repeated distensions evoked reproducible responses of sensation and compliance and/or elastance on a single day, providing a conditioning distension preceded them. Day-to-day variability was also sufficiently small to allow valid comparisons to be made on different days in healthy persons. The configuration of the distension profile (phasic, staircase, or ramp) and the rate of inflation (from 1 to 40 ml/s) had little effect on distensibility or perception. Perceptions were sometimes transient and sometimes constant, but no relationship was found between these temporal features and the magnitude of the stimulus. These observations help provide a basis as to how the responses to rectal distension can be best studied.
Reduction of acute and reactivated colitis in rats by an inhibitor of neutrophil activation
Authors: Wallace John L. , McKnight Webb , Asfaha Samuel , Liu David Y.
Published: December 2017

Neutrophils have been implicated as major contributors to tissue injury in inflammatory bowel disease. In this study, we have assessed the effects of an inhibitor of neutrophil activation and adherence, NPC-18915 (4-{2-[2-(2-benzofuranyl)phenyl]-(E)-ethenyl}benzoic acid sodium salt), in models of both acute and reactivated colitis. Acute colitis was induced by intracolonic administration of a hapten. In other rats, colitis was reactivated 6 wk after a bout of acute colitis by subcutaneous administration of the hapten. NPC-18915 given during the first 4 days after induction of acute colitis significantly reduced tissue injury and the incidence of diarrhea and adhesions. When treatment of NPC-18915 was initiated after colitis was firmly established (48 h posthapten), it did not produce a significant effect. NPC-18915 was effective at significantly reducing colonic injury and granulocyte infiltration in the reactivated colitis model, and a similar effect could be observed in rats treated with antineutrophil serum. These results demonstrate that an inhibitor of neutrophil activation is effective in both acute and reactivated colitis, although in the former case, effectiveness is only seen when the drug is given before full establishment of colitis. These results also suggest that neutrophils are a critical effector cell of hapten-induced colitis in the rat, particularly in the case of reactivated colitis.
Selecting agent hygromycin B alters expression of glucose-regulated genes in transfected Caco-2 cells
Authors: Rodolosse Annie , Barbat Alain , Chantret Isabelle , Lacasa Michel , Brot-Laroche Edith , Zweibaum Alain , Rousset Monique
Published: December 2017

Incorporation into plasmids of genes conferring resistance to aminoglycoside antibiotics such as hygromycin B is currently utilized for selection in experiments involving gene transfer in eukaryotic cells. Using a subclone of Caco-2 cells stably transfected with an episomal plasmid containing the hygromycin resistance gene, we observed that transformed cells subcultured in the presence of hygromycin B exhibit, compared with the same cells subcultured in antibiotic-free medium, a sixfold increase in the rates of glucose consumption and lactic acid production and dramatic changes, at mRNA and protein level, of the expressions of sucrase-isomaltase and hexose transporter GLUT-2, which are downregulated, contrasting with an upregulation of hexose transporter GLUT-1. This occurs without significant modifications of the differentiation status of the cells, as demonstrated by the normal expression of villin, ZO-1, dipeptidyl peptidase IV, or Na+-K+-ATPase. The plasmid copy number is, however, the same, whether or not the cells are cultured in the presence of hygromycin B. These results draw attention to the need to consider antibiotic-dependent alterations of metabolism and gene expression in transfection experiments.
Subepithelial fibroblast cell lines from different levels of gut axis display regional characteristics
Authors: Plateroti Michelina , Rubin Deborah C. , Duluc Isabelle , Singh Renu , Foltzer-Jourdainne Charlotte , Freund Jean-Noël , Kedinger Michèle
Published: December 2017

The intestine is characterized by morphofunctional differences along the proximodistal axis. The aim of this study was to derive mesenchymal cell lines representative of the gut axis. We isolated and cloned rat intestinal subepithelial myofibroblasts raised from 8-day proximal jejunum, distal ileum, and proximal colon lamina propria. Two clonal cell lines from each level of the gut were characterized. They 1) express the specific markers vimentin, smooth muscle α-actin, and smooth muscle myosin heavy chain, revealed by immunofluorescence microscopy and 2) distinctly support endodermal cell growth in a coculture model, depending on their regional origin, and 3) the clones raised from the various proximodistal regions maintain the same pattern of morphogenetic and growth and/or differentiation factor gene expression as in vivo: hepatocyte growth and/or scatter factor and transforming growth factor-β1 mRNAs analyzed by RT-PCR were more abundant, in the colon and ileal clones and mucosal connective tissue, respectively. In addition, epimorphin mRNA studied by Northern blot was also the highest in one ileal clone, in which it was selectively upregulated by all-trans retinoic acid (RA) treatment. Epimorphin expression in isolated 8-day intestinal lamina propria was higher in the distal small intestine and proximal colon than in the proximal small intestine. In conclusion, we isolated and characterized homogeneous cell subtypes that can now be used to approach the molecular regulation of the epithelium-mesenchyme-dependent regional specificity along the gut.
Corticosterone increase inhibits stress-induced gastric erosions in rats
Authors: Filaretova L. P. , Filaretov A. A. , Makara G. B.
Published: December 2017

The role of glucocorticoids released in response to stress in the pathogenesis of stress-induced gastric erosions has been reevaluated. Gastric erosions elicited in male rats by 3-h cold-restraint or water-restraint stresses were studied after acute reduction of corticosterone release or occupation of glucocorticoid receptors by the antagonist RU-38486 during stress. Stress-induced corticosterone production was reduced by creating a lesion on the hypothalamic paraventricular nucleus (PVN) 4 days before stress as well as by pretreatment with a rabbit antiserum to adrenocorticotropin (ACTH) 30 min before stress. RU-38486 (10 mg/kg po) was administered 20 min before and 60 min after the onset of stress. Corticosterone for replacement was injected 15 min before the onset of stress to mimic stress-induced corticosterone response. Plasma corticosterone levels were measured by fluorometry or RIA. Gastric erosions were quantitated by measuring the area of damage. Four days after PVN lesion, stress-induced corticosterone release was decreased and gastric erosions were increased. Injecting corticosterone significantly attenuated the effect of PVN lesion on gastric erosions. The ACTH antiserum inhibited corticosteroid secretion in response to stress and markedly increased gastric erosions. The administration of the glucocorticoid/progesterone antagonist RU-38486 significantly potentiated the formation of stress-induced gastric erosions. These observations support the suggestion that glucocorticoids released during stress have a gastroprotective action rather than an ulcerogenic effect as was generally accepted.
Colonic mucin release in response to immobilization stress is mast cell dependent
Authors: Castagliuolo Ignazio , Wershil Barry K. , Karalis Katia , Pasha Asiya , Nikulasson Sigfus T. , Pothoulakis Charalabos
Published: December 2017

We recently reported that immobilization stress increased colonic motility, mucin, and prostaglandin E2(PGE2) release and mucosal mast cell degranulation in rat colon [ Proc. Natl. Acad. Sci. USA 93: 12611–12615, 1996; Am. J. Physiol. 271 ( Gastrointest. Liver Physiol. 34): G884–G892, 1996]. To directly assess the contribution of mast cells, we compared colonic responses to stress in mast cell-deficient KitW/ KitW−vand normal (+/+) mice. Mucin and PGE2release were measured in colonic explants cultured from KitW/ KitW−vand (+/+) mice 30 min after immobilization stress. We found that stress stimulated colonic mucin release (1.8-fold), goblet cell depletion (3-fold), and PGE2(2.3-fold) release in (+/+) but not mast cell-deficient KitW/ KitW−vmice. However, mast cell-deficient mice that had their mast cell population reconstituted by injection of bone marrow-derived mast cells from (+/+) mice had colonic responses to stress similar to those of normal (+/+) mice. In contrast, colonic transit changes in response to stress, estimated by fecal output, were similar between KitW/ KitW−vand normal (+/+) mice. We conclude that mast cells regulate colonic mucin and PGE2release but not colonic transit changes in response to immobilization stress.
H. pyloristimulates gastrin release from canine antral cells in primary culture
Authors: Lehmann Frank S. , Schiller Neal , Cover Timothy , Hatch Ritchard , Seensalu Rein , Kato Kimitoshi , Walsh John H. , Soll Andrew H.
Published: December 2017

Patients chronically infected with Helicobacter pylori are known to have hypergastrinemia. Previous studies have demonstrated the stimulation of gastrin from isolated G cells by monocytes and cytokines. The aim of this study was to determine if H. pylori can directly stimulate gastrin secretion. The secretion of gastrin from canine G cells in 48-h primary cultures was investigated using either live H. pylori bacteria or various bacterial extracts from three well-characterized strains. Whole bacterial sonic extracts and water-extracted surface proteins, but not PBS extracts, from strains 43579 (CagA+/VacA+), 60190 (CagA+/VacA+), and 60190:v1 (CagA+/VacA−) significantly stimulated gastrin release. Controls demonstrated that gastrin stimulation by the sonic extracts was not due to a direct toxic effect on G cells. We conclude that H. pylori produces a soluble factor(s), which can directly stimulate gastrin release in enriched canine G cell cultures. This stimulatory effect may play an important role in the H. pylori-associated hypergastrinemia and subsequent development of peptic ulcer disease.
Characterization of rat epimorphin/syntaxin 2 expression suggests a role in crypt-villus morphogenesis
Authors: Goyal Alka , Singh Renu , Swietlicki Elzbieta A. , Levin Marc S. , Rubin Deborah C.
Published: December 2017

The rodent intestinal mucosa undergoes a remarkable morphogenesis as the crypt-villus axis is formed. Endoderm-mesenchymal interactions play a critical role in this process. Epimorphin is a mesenchymal protein postulated to play a role in lung and skin morphogenesis. The rat homologue, syntaxin 2, belongs to a family of integral membrane proteins that function in vesicle docking and fusion. To clarify its role in fetal gut morphogenesis, epimorphin expression was examined during ontogeny, in an isograft model of ischemic injury and mucosal repair, and during intestinal adaptation after small bowel resection. Epimorphin/syntaxin 2 mRNA levels were increased in fetal gut during lumen formation and villus morphogenesis. mRNA levels remained elevated in the first 2 wk after birth and then declined at weaning. In situ hybridization showed epimorphin/syntaxin 2 mRNA in gestational day 14( G14) and G15 intestinal mesenchymal cells and in the mucosal lamina propria during villus formation. Epimorphin/syntaxin 2 mRNA expression increased during villus repair in the isograft. In contrast, in the early stages of intestinal adaptation after small bowel resection, epimorphin/syntaxin 2 mRNA expression was suppressed in the adapting gut. We conclude the cell-specific and temporal patterns of epimorphin expression in the models used in this study suggest a role in the morphogenesis of the crypt-villus axis.