bluuebunny/crossref_metadata_2025 huggingface dataset:
Intestinal inflammation: a complex interplay of immune and nonimmune cell interactions
Authors: Fiocchi Claudio
Published: December 2017

Intestinal inflammation has traditionally been viewed as a process in which effector immune cells cause the destruction of other mucosal cells that behave as passive bystander targets. Progress in understanding the process of intestinal inflammation has led to a much broader and more integrated picture of the various mucosal components, a picture in which cytokines, growth factors, adhesion molecules, and the process of apoptosis act as functional mediators. Essentially all cellular and acellular components can exert immunelike activities, modifying the classical concept of selected immune cells acting on all other cells that has been the dogma of immunologically mediated tissue damage for decades. The existence of specialized communication pathways between epithelial cells and T cells is well documented, including abnormal epithelial cell-mediated T cell activation during inflammation. Mesenchymal cells contribute to fibrosis in the inflamed gut but are also responsible for retention and survival of leukocytes in the mucosa. In chronically inflamed intestine the local microvasculature displays leukocyte hyperadhesiveness, a phenomenon that probably contributes to persistence of inflammation. The extracellular matrix regulates the number, location, and activation of leukocytes, while metalloproteinases regulate the quantity and type of deposited matrix proteins. This evidence from the intestinal system, consolidated with the use of data from other organs and systems, reveals a rich network of reciprocal and finely orchestrated interactions among immune, epithelial, endothelial, mesenchymal, and nerve cells and the extracellular matrix. Although these interactions occur under normal conditions, the dysfunction of any component of this highly integrated mucosal system may lead to a disruption in communication and result in pathological inflammation.
Influence of altered tongue contour and position on deglutitive pharyngeal and UES function
Authors: Ali G. N. , Cook I. J. , Laundl T. M. , Wallace K. L. , De Carle D. J.
Published: December 2017

The potential influence of altered lingual position and contour during the bolus loading phase of the swallow in mediating the swallowed bolus volume-dependent regulation of upper esophageal sphincter (UES) relaxation and opening was studied in 15 healthy volunteers using simultaneous videoradiography and manometry. A maxillary dental splint modulated tongue deformity during the early oral phase of deglutition. We examined the effect of the splint and swallowed bolus density on bolus volume-dependent changes in the timing of events in the swallow sequence and on hypopharyngeal intrabolus and midpharyngeal pressures. Peak midpharyngeal pressure ( P = 0.001) and hypopharyngeal intrabolus pressure ( P = 0.04) were significantly reduced by the splint. The normal volume-dependent earlier onset of sphincter relaxation and opening was preserved with the splint in situ. The splint significantly delayed the onset of hyoid motion and UES relaxation and opening without influencing transit times or total swallow duration. Alterations in tongue contour and position reduce intrabolus pressure and pharyngeal contraction without influencing normal bolus volume-dependent regulation of timing of UES relaxation and opening.
pH-dependent changes of nitric oxide, peroxynitrite, and reactive oxygen species in hepatocellular damage
Authors: Shu Zhijun , Jung Martin , Beger Hans-G. , Marzinzig Michael , Han Fuli , Butzer Urwe , Bruckner Uwe B. , Nussler Andreas K.
Published: December 2017

Low arterial blood pH and sustained nitric oxide (NO) production are critical parameters in inflammatory events such as sepsis, and appropriate treatment is still under debate. Because the stability of nitrogen and oxygen intermediates is dependent on the surrounding pH, we investigated whether the relationship among NO, peroxynitrite (ONOO−), and reactive oxygen species production also depends on the pH value, particularly with respect to their effects on hepatocellular damage. Our studies demonstrate that the extracellular pH influences NO and hydroxyl radical (OH) production in hepatocytes. Acidification (pH 7.0) of the medium revealed a significant increase ( P < 0.05) of OH-like radicals, enhanced hepatocellular damage, and a sharp drop in cellular glutathione (GSH) content compared with levels measured at physiological or alkaline pH conditions. Furthermore, inhibition of NO synthesis at all pH conditions resulted in decreased NO production and cellular GSH levels but a simultaneous increase of OH-like radicals and hepatocellular damage with a maximum seen at pH 7.0. Our results suggest that hepatocellular damage is in part regulated by the surrounding pH and that inhibition of NO synthesis at acidic conditions (e.g., in sepsis) leads to increased reactive oxygen-mediated cell injury.
Duodenal motility in fasting dogs: humoral and neural pathways mediating the colonic brake
Authors: Wen J. , Leon E. Luque-De , Kost L. J. , Sarr M. G. , Phillips S. F.
Published: December 2017

We have previously described a negative feedback loop that inhibits duodenal motility when nutrients are infused into the ileum and colon. In the present study, we examined the role of extrinsic innervation and plasma levels of peptide YY (PYY) in mediating this phenomenon. We perfused neurally intact ( n = 5 dogs) or extrinsically denervated ( n = 6 dogs) isolated loops of proximal colon with isomolar NaCl or a mixed-nutrient solution at 2 and 6 ml/min for 4 h during fasting or for 2 h beginning 15 min after a meal. Both rates of infusion with NaCl prolonged the cycle length of the duodenal migrating motor complex (MMC) in the group with neurally intact loops but not in the group with extrinsically denervated loops. Nutrient infusions increased the MMC cycle length in both groups. Integrated plasma concentrations of PYY were increased by nutrients but not by NaCl in both groups. These data suggest that increased volumes and unabsorbed nutrients in the proximal colon alter proximal small bowel motility. Volume-induced effects are mediated via extrinsic nerves, whereas nutrient-induced effects may be mediated by humoral factors, such as plasma PYY.
TNF-α modulates expression of the tissue transglutaminase gene in liver cells
Authors: Kuncio Gerald S. , Tsyganskaya Mariya , Zhu Jianling , Liu Shu-Ling , Nagy Laszlo , Thomazy Vilmos , Davies Peter J. A. , Zern Mark A.
Published: December 2017

One of several postulated roles for tissue transglutaminase (tTG) is the stabilization and assembly of extracellular matrix via peptide cross-linking. We previously determined that tTG activity increased in an animal model of hepatic fibrogenesis and in human liver disease. To further study the role of tTG in liver disease, we initiated investigations into the effect of a proinflammatory mediator, tumor necrosis factor (TNF)-α, on tTG activity in cultured liver cells. Treatment of human Hep G2 cells with 1 ng/ml TNF-α increased [14C]putrescine cross-linking to cellular proteins. An increase in tTG mRNA content was observed 1 h after addition of TNF-α, and levels of tTG mRNA remained elevated after 24 h. Hep G2 cells, transiently transfected with a luciferase reporter containing 1.67 kb of the human tTG promoter, showed an increase in reporter activity after addition of TNF-α. Gel shift experiments using nuclear extracts from TNF-α-treated cells and oligonucleotides containing the tTG nuclear factor (NF)-κB motif revealed increased binding, concordant with mRNA data. Transient transfections with a truncated reporter construct lacking the tTG NF-κB sequence showed an attenuated response to TNF-α treatment. Similar responses were seen in stably transfected HeLa cells. Primary hepatocytes isolated from a trangenic mouse line containing the mouse tTG promoter driving the β-galactosidase reporter, show similar time-dependent increases in promoter activity when treated with TNF-α. Furthermore, Hep G2 cells are incapable of upmodulating tTG promoter reporter activity in the presence of TNF-α when those cells overexpress a transdominant, negative mutant NF-κB subunit. Because TNF-α expression is upregulated in hepatic inflammation, the data suggest TNF-α-mediated increases in tTG expression may play an important role in the process of hepatic fibrogenesis.
Vitamin D increases tight-junction conductance and paracellular Ca2+ transport in Caco-2 cell cultures
Authors: Chirayath Mary V. , Gajdzik Leszek , Hulla Wolfgang , Graf Jürg , Cross Heide S. , Peterlik Meinrad
Published: December 2017

We investigated the effects of 1α,25-dihydroxyvitamin D3[1,25(OH)2D3] on paracellular intestinal Ca2+absorption by determination of transepithelial electric resistance (TEER), as a measure of tight-junction ion permeability and bidirectional transepithelial45Ca2+fluxes in confluent Caco-2 cell cultures. The rise of TEER to steady-state levels of ∼2,000 Ω ⋅ cm2 was significantly attenuated by 1,25(OH)2D3(by up to 50%) in a dose-dependent fashion between 10−11 and 10−8 M. Synthetic analogs of 1,25(OH)2D3, namely, 1α,25-dihydroxy-16-ene,23-yne-vitamin D3 and 1α,25-dihydroxy-26,27-hexafluoro-16-ene,23-yne-vitamin D3, exhibited similar biopotency, whereas their genomically inactive 1-deoxy congeners were only marginally effective. Enhancement of transepithelial conductance of Caco-2 cell monolayers by vitamin D was accompanied by a significant increase in bidirectional transepithelial45Ca2+fluxes. Although 1,25(OH)2D3also induced cellular45Ca2+uptake from the apical aspect of Caco-2 cell layers and upregulated the expression of calbindin-9kDa mRNA, no significant contribution of the Ca2+-adenosinetriphosphatase-mediated transcellular pathway to transepithelial Ca2+ transport could be detected. Therefore stimulation of Ca2+fluxes across confluent Caco-2 cells very likely results from a genomic effect of vitamin D sterols on assembly and permeability of tight-junctional complexes.
Nitric oxide regulates energy metabolism and Bcl-2 expression in intestinal epithelial cells
Authors: Nishikawa Manabu , Takeda Kenta , Sato Eisuke F. , Kuroki Tetso , Inoue Masayasu
Published: December 2017

Nitric oxide (NO) inhibits the respiration of mitochondria and enteric bacteria, particularly under low O2concentration, and induces apoptosis of various types of cells. To gain insight into the molecular role of NO in the intestine, we examined its effects on the respiration, Ca2+status, and expression of Bcl-2 in cultured intestinal epithelial cells (IEC-6). NO reversibly inhibited the respiration of IEC-6 cells, especially under physiologically low O2concentration. Although NO elevated cytosolic Ca2+as determined by the fura 2 method, the cells were fairly resistant to NO. Kinetic analysis revealed that prolonged exposure to NO elevated the levels of Bcl-2 and suppressed the NO-induced changes in Ca2+status of the cells. Because Bcl-2 possesses antiapoptotic function, toxic NO effects might appear minimally in enterocytes enriched with Bcl-2. Thus NO might effectively exhibit its antibacterial action in anaerobic intestinal lumen without inducing apoptosis of Bcl-2-enriched mucosal cells.
Pharmacodynamic profile of a novel inhibitor of the hepatic glucose-6-phosphatase system
Authors: Herling Andreas W. , Burger Hans-Joerg , Schwab Dietmar , Hemmerle Horst , Below Peter , Schubert Gerrit
Published: December 2017

The glucose-6-phosphatase (G-6- Pase) system catalyzes the terminal enzymatic step of gluconeogenesis and glycogenolysis. Inhibition of the G-6- Pase system in the liver is expected to result in a reduction of hepatic glucose production irrespective of the relative contribution of gluconeogenesis or glycogenolysis to hepatic glucose output. In isolated perfused rat liver, S-3483, a derivative of chlorogenic acid, produced concentration-dependent inhibition of gluconeogenesis and glycogenolysis in a similar concentration range. In fed rats, glucagon-induced glycogenolysis resulted in hyperglycemia for nearly 2 h. Intravenous infusion of 50 mg ⋅ kg−1⋅ h−1S-3483 prevented the hyperglycemic peak and subsequently caused a further lowering of blood glucose. In 24-h starved rats, in which normoglycemia is maintained predominantly by gluconeogenesis, intravenous infusion of S-3483 resulted in a constant reduction of blood glucose levels. Intrahepatic concentrations of glucose-6-phosphate (G-6- P) and glycogen were significantly increased at the end of both in vivo studies. In contrast, lowering of blood glucose in starved rats by 3-mercaptopicolinic acid was accompanied by a reduction of G-6- P and glycogen. Our results demonstrate for the first time in vivo a pharmacologically induced suppression of hepatic G-6- P activity with subsequent changes in blood glucose levels.
III. Asymmetry in plasma membrane signal transduction: lessons from brush-border Na+/H+exchangers
Authors: Donowitz M. , Khurana S. , Tse C. M. , Yun C. H. C.
Published: December 2017

Signal transduction in epithelial cells adds another level of complexity to the signaling that occurs in symmetrical cells, in the form of the need to coordinate and keep separate signals at the apical and basolateral membranes. Regulation by protein kinases of ileal NaCl absorption and its component brush-border Na+/H+exchanger are used as an example of how signaling in epithelial cells must deal with spatial localization of signals, protein-protein interactions, signaling molecules, and the involvement of the transport protein being regulated in collecting and focusing the signals generated at the receptor and beyond.
Lithocholyltaurine interacts with cholinergic receptors on dispersed chief cells from guinea pig stomach
Authors: Raufman Jean-Pierre , Zimniak Piotr , Bartoszko-Malik Anita
Published: December 2017

Although bile acids damage gastric mucosa, the mechanisms underlying tissue injury induced by these agents are not well understood. To determine whether bile acids alter gastric secretory function, we investigated the actions of sodium cholate, deoxycholate, lithocholate, and their taurine and glycine conjugates on a highly homogeneous population of gastric chief cells. Lithocholyltaurine (LCT), a particularly injurious bile acid, caused a threefold increase in pepsinogen secretion (detectable with 100 nM and maximal with 10 μM LCT). When combined with other secretagogues, increasing concentrations of LCT caused progressive inhibition of carbamylcholine (carbachol)-induced pepsinogen secretion but did not alter CCK- or 8-bromo-cAMP-induced secretion. Taurine and unconjugated lithocholate did not alter basal or carbachol-induced secretion. These observations suggested that LCT is a partial cholinergic agonist. To test this hypothesis, we examined the actions of the cholinergic antagonist atropine on LCT-induced pepsinogen secretion. Atropine (10 μM) abolished carbachol- and LCT-induced pepsinogen secretion. Likewise, carbachol (0.1 mM) and LCT (1 mM) induced an atropine-sensitive, two- to threefold increase in cellular levels of inositol 1,4,5-trisphosphate. We examined the actions of LCT on binding of the cholinergic radioligand [ N-methyl-3H]scopolamine ([3H]NMS) to chief cells. Half-maximal inhibition of [3H]NMS binding was observed with ∼0.5 mM carbachol and 1 mM LCT. These results indicate that the bile acid LCT is a partial agonist for muscarinic cholinergic receptors on gastric chief cells.
Kinetics of particle uptake in the domes of Peyer’s patches
Authors: Beier Rita , Gebert Andreas
Published: December 2017

Uptake of particulate antigenic matter, including microorganisms and vaccine-bearing microspheres, by the intestinal mucosa takes place in the domes of the gut-associated lymphoid tissues and is achieved by membranous (M) cells, which continuously transport particles from the lumen to the underlying tissue where some particle components initiate immune reactions. Using yeast as tracer, we investigated the kinetics of particle uptake in the Peyer’s patches of pigs. A suspension of baker’s yeast ( Saccharomyces cerevisiae) was injected into the gut lumen of anesthetized minipigs; the position of yeast cells in the tissue was determined after 1, 2.5, 4, and 24 h using fluorescence light- and thin-section electron microscopy. After 1 h, 18.5% of all M cells had taken up or were in close contact with yeast cells. The intercellular space of the epithelium contained a maximum of 60.8% of all yeast cells found in the tissue after 2.5 h, but only 1.3% had been phagocytosed by macrophages. After 4 h most yeast cells (77.8%) were found beneath the basal lamina, and most of these (89%) were found in macrophages. No yeast cells were detected in the Peyer’s patch domes 24 h after application. The data show that transcytosis of yeast particles (3.4 ± 0.8 μm in diameter) by M cells takes <1 h. Without significant phagocytosis by intraepithelial macrophages, the particles migrate down to and across the basal lamina within 2.5–4 h, where they quickly get phagocytosed and transported out of the Peyer’s patch domes.
V. Gastrointestinal peptide signaling through tyrosine phosphorylation of focal adhesion proteins
Authors: Rozengurt Enrique
Published: December 2017

Gastrointestinal (GI) peptides (also referred to as neuropeptides or regulatory peptides), including the mammalian bombesin-like peptides gastrin and CCK, elicit the synthesis of classic second messengers (e.g., Ca2+, diacylglycerol, and cAMP) and the consequent stimulation of serine/threonine protein kinase cascades. An emerging theme in signal transduction is that these agonists also induce rapid and coordinate tyrosine phosphorylation of a set of focal adhesion proteins, including the nonreceptor tyrosine kinase p125fakand the adaptor proteins p130casand paxillin. GI peptide-mediated induction of tyrosine phosphorylation of these focal adhesion proteins is critically dependent on the integrity of the actin cytoskeleton and on functional Rho. The purpose of this article is to review recent advances in unraveling this novel tyrosine kinase pathway(s), because it appears to play a fundamental role in the mediation of important biological effects induced by GI peptides, including cell migration and proliferation.
Cytokines induce NF-κB in activated but not in quiescent rat hepatic stellate cells
Authors: Hellerbrand C. , Jobin C. , Licato L. L. , Sartor R. B. , Brenner D. A.
Published: December 2017

The hepatic stellate cell (HSC), after a fibrogenic stimulus, is transformed from a quiescent to an activated phenotype, including the induction of responsiveness to a variety of agonists. We investigated the activation of nuclear factor-κB (NF-κB) and the expression of the NF-κB-responsive genes intercellular adhesion molecule 1 (ICAM-1) and macrophage inflammatory protein-2 (MIP-2) in freshly isolated and culture-activated HSC by tumor necrosis factor-α (TNF-α) or interleukin-1β. Inhibitor-κB was rapidly (<15 min) degraded, and NF-κB activity was induced in culture-activated but not in freshly isolated HSC after cytokine stimulation. After 30 min of stimulation, immunofluorescence revealed that the NF-κB p65 subunit was predominantly found in the nuclei of activated HSC compared with the cytoplasmic localization in unstimulated cells. No nuclear translocation appeared in freshly isolated HSC after stimulation, despite the presence of functional TNF-α receptors. NF-κB nuclear translocation appeared first partially after 4–5 days and completely after 9 days in culture. Consistent with this time course TNF-α induced the mRNA of the NF-κB-dependent genes ICAM-1 and MIP-2 in activated but not in quiescent HSC. Therefore, cytokines induce NF-κB activity and ICAM-1 and MIP-2 mRNAs in activated but not in quiescent HSC, through a postreceptor mechanism of regulation.
Intra-acinar cell activation of trypsinogen during caerulein-induced pancreatitis in rats
Authors: Hofbauer B. , Saluja A. K. , Lerch M. M. , Bhagat L. , Bhatia M. , Lee H. S. , Frossard J. L. , Adler G. , Steer M. L.
Published: December 2017

Supramaximal stimulation of the pancreas with the CCK analog caerulein causes acute edematous pancreatitis. In this model, active trypsin can be detected in the pancreas shortly after the start of supramaximal stimulation. Incubation of pancreatic acini in vitro with a supramaximally stimulating caerulein concentration also results in rapid activation of trypsinogen. In the current study, we have used the techniques of subcellular fractionation and both light and electron microscopy immunolocalization to identify the site of trypsinogen activation and the subsequent fate of trypsin during caerulein-induced pancreatitis. We report that trypsin activity and trypsinogen-activation peptide (TAP), which is released on activation of trypsinogen, are first detectable in a heavy subcellular fraction. This fraction is enriched in digestive enzyme zymogens and lysosomal hydrolases. Subsequent to trypsinogen activation, both trypsin activity and TAP move to a soluble compartment. Immunolocalization studies indicate that trypsinogen activation occurs in cytoplasmic vacuoles that contain the lysosomal hydrolase cathepsin B. These observations suggest that, during the early stages of pancreatitis, trypsinogen is activated in subcellular organelles containing colocalized digestive enzyme zymogens and lysosomal hydrolases and that, subsequent to its activation, trypsin is released into the cytosol.
Bacteria rapidly colonize and modulate healing of gastric ulcers in rats
Authors: Elliott Susan N. , Buret André , McKnight Webb , Miller Mark J. S. , Wallace John L.
Published: December 2017

The stomach is generally regarded as an environment that is not conducive to bacterial colonization. In this study, we examined the possibility that this changes significantly when an ulcer has formed and that colonization of ulcers interferes with the normal healing process. Gastric ulcers were induced by serosal application of acetic acid. The relationship between ulcer healing and bacterial colonization was examined. The effects of antibiotics, induction of Lactobacilluscolonization, and selective colonization with an antibiotic resistant strain of Escherichia coli on ulcer healing were examined. Within 6–12 h of their induction, gastric ulcers were colonized by a variety of bacteria, with gram-negative bacteria predominating. Suppression of colonization with antibiotics resulted in marked acceleration of healing. Induction of Lactobacillus colonization also accelerated ulcer healing. The beneficial effects of antibiotics were reversed through selective colonization with antibiotic-resistant E. coli. Bacterial colonization occurred irrespective of the method used to induce the ulcer. This study demonstrates that colonization of gastric ulcers in rats occurs rapidly and significantly impairs ulcer healing. This effect appeared to be primarily attributable to gram-negative bacteria.
Demonstration and immunolocalization of ATP diphosphohydrolase in the pig digestive system
Authors: Sévigny Jean , Grondin Gilles , Gendron Fernand-Pierre , Roy Julie , Beaudoin Adrien R.
Published: December 2017

Two isoforms of ATP diphosphohydrolase (ATPDase; EC 3.6.1.5 ) have been previously characterized, purified, and identified. This enzyme is an ectonucleotidase that catalyzes the sequential release of γ- and β-phosphate groups of triphospho- and diphosphonucleosides. One of its putative roles is to modulate the extracellular concentrations of purines in different physiological systems. The purpose of this study was to define, identify, and localize these two isoforms of ATPDase in the pig digestive system. ATPDase activity was measured in pig stomach, duodenum, pancreas, and parotid gland. Enzyme assays, electrophoretograms, and Western blots with a polyclonal antibody that recognizes both isoforms demonstrate the presence of ATPDase in these organs. Immunolocalization showed intense reactions with gastric glands (parietal and chief cells), intestine (columnar epithelial cells), parotid gland, and pancreas. Smooth muscle cells all along the digestive tract were also highly reactive. Considering the variety of purinoceptors associated with the digestive system, the ATPDase is strategically positioned to modulate purine-mediated actions such as electrolyte secretion, glandular secretion, smooth muscle contraction, and blood flow.
Monochloramine induced DNA fragmentation in gastric cell line MKN45
Authors: Suzuki Hidekazu , Seto Koichi , Mori Mikiji , Suzuki Masayuki , Miura Soichiro , Ishii Hiromasa
Published: December 2017

Monochloramine (NH2Cl) is known to be one of the virulence factors in Helicobacter pylori-associated gastric mucosal injury. The present study was designed to examine NH2Cl-evoked DNA fragmentation in the gastric epithelial cell line MKN45. NH2Cl was produced by mixing NH3with sodium hypochlorite (NaClO). MKN45 cells were exposed to NH2Cl, NH3, or NaClO in Hanks’ balanced salt solution. DNA cleavage was evaluated quantitatively by photometeric enzyme immunoassay for the in vitro determination of cytoplasmic mono- and oligonucleosomes. Damage to the plasma membrane was assessed by measuring the activity of lactate dehydrogenase in the supernatants. Separately, DNA ladder formation was performed to confirm the incidence of DNA fragmentation. NH2Cl (0.001–0.01 mM) significantly increased the cytoplasmic mono- and oligonucleosomes, suggesting the incidence of DNA cleavage. The DNA ladder was clearly evoked by NH2Cl. NH2Cl induced a DNA fragmentation, one of the important aspects in apoptosis, in the gastric cell line MKN45.
Zymogen proteolysis within the pancreatic acinar cell is associated with cellular injury
Authors: Grady T. , Mah’Moud M. , Otani T. , Rhee S. , Lerch M. M. , Gorelick F. S.
Published: December 2017

The pathological activation of digestive zymogens within the pancreatic acinar cell probably plays a central role in initiating many forms of pancreatitis. To examine the relationship between zymogen activation and acinar cell injury, we investigated the effects of secretagogue treatment on isolated pancreatic acini. Immunofluorescence studies using antibodies to the trypsinogen-activation peptide demonstrated that both CCK (10−7 M) hyperstimulation and bombesin (10−5 M) stimulation of isolated acini resulted in trypsinogen processing to trypsin. These treatments also induced the proteolytic processing of procarboxypeptidase A1 to carboxypeptidase A1(CA1). After CCK hyperstimulation, most CA1remained in the acinar cell. In contrast, the CA1 generated by bombesin was released from the acinar cell. CCK hyperstimulation of acini was associated with cellular injury, whereas bombesin treatment did not induce injury. These studies suggest that 1) proteolytic zymogen processing occurs within the pancreatic acinar cell and 2) both zymogen activation and the retention of enzymes within the acinar cell may be required to induce injury.
Cellular pathways of mast cell- and capsaicin-sensitive nerve-evoked ileal submucosal arteriolar dilations
Authors: Atwood L. , James C. , Morris G. P. , Vanner S.
Published: December 2017

This study characterized mast cell- and capsaicin-sensitive sensory nerve vasodilator mechanisms regulating submucosal arterioles in the guinea pig ileum. The outside diameter of arterioles in in vitro submucosal preparations from milk-sensitized guinea pigs was monitored using videomicroscopy. Superfusion of the cow’s milk protein, β-lactoglobulin (β-Lg; 5 μM), evoked large dilations, which became completely desensitized. β-Lg-evoked dilations were blocked by pyrilamine or N G-monomethyl-l-arginine plus indomethacin but not by TTX. Electron microscopic studies revealed that mast cells, in preparations receiving β-Lg, demonstrated significant reductions of the dispersed and intact granule areas compared with preparations not exposed to β-Lg. Paired experiments were conducted to determine if capsaicin-sensitive, nerve-evoked responses involved mast cell degranulation. One preparation received capsaicin (200 nM) followed by β-Lg (5 μM); the other preparation received the drugs in reverse order. Prior treatment with capsaicin or β-Lg had no effect on subsequent dilations evoked by the alternate treatment. Electron microscopy showed that nerve-arteriole associations were 10 times closer than nerve-mast cell associations. Mast cell numbers were not increased by milk sensitization. These findings suggest that mast cell- and capsaicin-sensitive nerve-evoked vasodilator mechanisms act independently in a model in which mast cell numbers are not increased.
GLP-2 augments the adaptive response to massive intestinal resection in rat
Authors: Scott R. B. , Kirk D. , MacNaughton W. K. , Meddings J. B.
Published: December 2017

To determine whether treatment with a potent protease-resistant analog of human glucagon-like peptide 2 (GLP-2) might augment the adaptive response to massive intestinal resection, rats were divided into resected, which had 75% of the midjejunoileum removed, sham-resected, and nonsurgical groups. Within each group, animals were assigned to 21 days of treatment with the drug (0.1 μg/g of the GLP-2 analog in phosphate-buffered saline) or vehicle alone subcutaneously twice daily. Food intake; weight gain; jejunal and ileal diameters, total and mucosal wet weights per centimeter, crypt depths, and villus heights; mucosal sucrase activity, milligrams of protein per centimeter, and micrograms of DNA per centimeter; andd-xylose absorption were measured. There was a significant increase in diameter, total and mucosal wet weights per centimeter, crypt-villus height, sucrase activity, milligrams of protein per centimeter and micrograms of DNA per centimeter in both the jejunum and ileum in response to resection and a significant additive response to the GLP-2 analog in the jejunum but not in the ileum. The ratio of milligrams of protein per centimeter to micrograms of DNA per centimeter of mucosa was not different among groups, consistent with hyperplasia.d-Xylose absorption was significantly reduced in response to resection; however, the GLP-2 analog enhanced the absorptive capacity in control animals and restored the absorptive capacity in resected animals. Thus the GLP-2 analog induces mucosal hyperplasia and enhances the rate and magnitude of the proximal intestinal adaptive response to massive resection.
L-selectin and ICAM-1 mediate reperfusion injury and neutrophil adhesion in the warm ischemic mouse liver
Authors: Yadav Surinder S. , Howell David N. , Gao Wenshi , Steeber Douglas A. , Harland Robert C. , Clavien Pierre-Alain
Published: December 2017

Leukocytes recruited during ischemia-reperfusion to the liver are important mediators of injury. However, the mechanisms of leukocyte adhesion and the role of adhesion receptors in hepatic vasculature remain elusive. L-selectin may critically contribute to injury, priming adhesion for later action of intercellular adhesion molecule-1 (ICAM-1). Paired experiments were performed using mutant mice (L-selectin −/−, ICAM-1 −/−, and L-selectin/ICAM-1 −/−) and wild-type mice (C57BL/6) to investigate leukocyte adhesion in the ischemic liver. Leukocyte adhesion and infiltration were assessed histologically. Aspartate aminotransferase levels were significantly reduced (2- to 3-fold) in mutant vs. wild-type mice in most groups but most significantly after 90 min of partial hepatic ischemia. Leukocyte adhesion was significantly reduced in all mutant mice. Areas of microcirculatory failure, visualized by intravital microscopy, were prevalent in wild-type but virtually absent in L-selectin-deficient mice. After total hepatic ischemia for 75 or 90 min, survival was better in mutant L-selectin and L-selectin/ICAM-1 mice vs. wild-type mice and ICAM-1 mutants. In conclusion, L-selectin is critical in the pathogenesis of hepatic ischemia-reperfusion injury. Poor sinusoidal perfusion due to leukocyte adhesion and clot formation is a factor of injury and appears to involve L-selectin and ICAM-1 receptors.
Impact of fundoplication on bolus transit across esophagogastric junction
Authors: Kahrilas Peter J. , Lin Shezhang , Spiess Anita E. , Brasseur James G. , Joehl Raymond J. , Manka Michael
Published: December 2017

This study analyzed the effect of fundoplication on the mechanics of liquid and solid bolus transit across the esophagogastric junction (EGJ). The squamocolumnar junction was endoscopically clipped in seven controls, seven hiatal hernia patients, and seven patients after laparoscopic Nissen fundoplication. Concurrent manometry and fluoroscopy were done during swallows of liquid barium and a 13-mm-diameter marshmallow. The EGJ opening, pressure gradients, transit efficacy, and axial motion were measured. The axial motion of the EGJ was reduced in the fundoplication and hiatal hernia patients. The opening dimensions at the squamocolumnar junction were similar among groups, but in each case the constriction limiting flow to the stomach was at the hiatus and this was substantially narrowed with fundoplication. As a result, liquid intrabolus pressure was increased and marshmallow transit frequently required multiple swallows. We conclude that fundoplication limits the axial mobility of the EGJ and leads to a restricted hiatal opening. These alterations decrease the efficacy of solid and liquid transit into the stomach and are potential causes of dysphagia in this population.
Intestinal inflammation reduces expression of DRA, a transporter responsible for congenital chloride diarrhea
Authors: Yang Hongyun , Jiang Wen , Furth Emma E. , Wen Xiaoming , Katz Jonathan P. , Sellon Rance K. , Silberg Debra G. , Antalis Toni M. , Schweinfest Clifford W. , Wu Gary D.
Published: December 2017

The pathogenesis of diarrhea in intestinal inflammatory states is a multifactorial process involving the effects of inflammatory mediators on epithelial transport function. The effect of colonic inflammation on the gene expression of DRA (downregulated in adenoma), a chloride-sulfate anion transporter that is mutated in patients with congenital chloridorrhea, was examined in vivo as well as in an intestinal epithelial cell line. DRA mRNA expression was diminished five- to sevenfold in the HLA-B27/β2m transgenic rat compared with control. In situ hybridization showed that DRA, which is normally expressed in the upper crypt and surface epithelium of the colon, was dramatically reduced in the surface epithelium of the HLA-B27/β2m transgenic rat, the interleukin-10 (IL-10) knockout mouse with spontaneous colitis, and in patients with ulcerative colitis. Immunohistochemistry demonstrated that mRNA expression of DRA reflected that of protein expression in vivo. IL-1β reduced DRA mRNA expression in vitro by inhibiting gene transcription. The loss of transport function in the surface epithelium of the colon by attenuation of transporter gene expression, perhaps inhibited at the level of gene transcription by proinflammatory cytokines, may play a role in the pathogenesis of diarrhea in colitis.
Liver regeneration is transiently impaired in urokinase-deficient mice
Authors: Roselli Heather T. , Su Ming , Washington Kay , Kerins David M. , Vaughan Douglas E. , Russell William E.
Published: December 2017

To test the hypothesis that urokinase-type plasminogen activator (uPA) plays an important role in liver regeneration in vivo, partial hepatectomy was performed on wild-type and uPA-deficient (uPA−/−) mice. Mice were studied at 24, 44, and 96 h and at 8 days and 4 wk post-partial hepatectomy for evidence of regeneration, as measured by mitotic indexes and [3H]thymidine incorporation. In wild-type mice, thymidine incorporation peaked at 44 h and this index was reduced by 47% in uPA−/− mice ( P= 0.02). By 8 days, however, liver mass was comparable in both groups. Histological analysis revealed the presence of focal areas of fibrin deposition and cellular loss by 24 h that were more severe and prevalent in uPA−/− mice than in wild-type mice (62 and 23%, respectively; χ2= 3.939, P = 0.047). In contrast, regeneration was not impaired in uPA receptor (uPAR)-deficient mice at 24 and 44 h. Taken together, these data indicate that uPA, independent of its interaction with the uPAR, plays an important role in liver regeneration in vivo.
Long- and short-termd-α-tocopherol supplementation inhibits liver collagen α1(Ι) gene expression
Authors: Chojkier Mario , Houglum Karl , Lee Kwan S. , Buck Martina
Published: December 2017

We analyzed the role of oxidative stress on liver collagen gene expression in vivo. Long- and short-term supplementation with the lipophilic antioxidantd-α-tocopherol (40 IU/day for 8 wk or 450 IU for 48 h) to normal C57BL/6 mice selectively decreased liver collagen mRNA by ∼70 and ∼60%, respectively. In transgenic mice, the −0.44 kb of the promoter and the first intron of the human collagen α1(Ι) gene were sufficient to confer responsiveness to d-α-tocopherol. Inhibition of collagen α1(Ι) transactivation in primary cultures of quiescent stellate cells from these transgenic animals byd-α-tocopherol required only −0.44 kb of the 5′ regulatory region. This regulation resembled that of the intact animal followingd-α-tocopherol treatment and indicates that d-α-tocopherol may act directly on stellate cells. Transfection of stellate cells with collagen- LUC chimeric genes allowed localization of an “antioxidant”-responsive element to the −0.22 kb of the 5′ region excluding the first intron. These findings suggest that oxidative stress, independently of confounding variables such as tissue necrosis, inflammation, cell activation, or cell proliferation, modulates in vivo collagen gene expression.
V. Necrapoptosis and the mitochondrial permeability transition: shared pathways to necrosis and apoptosis
Authors: Lemasters John J.
Published: December 2017

Opening of a high-conductance pore conducting solutes of molecular mass <1,500 Da causes onset of the mitochondrial permeability transition (MPT). Cyclosporin A blocks this pore and prevents acute necrotic cell death in several models. Confocal microscopy directly visualizes onset of the MPT during acute cytotoxicity from the movement of the green-fluorescing fluorophore, calcein, into the mitochondria from the cytosol. The MPT also plays a causative role in tumor necrosis factor-α-induced apoptosis in hepatocytes. Progression to apoptosis or necrosis after the MPT may depend on the presence or absence, respectively, of ATP. Often, features of both apoptotic and necrotic cell death develop after death signals and toxic stresses. The term “necrapoptosis” is introduced to emphasize the shared pathways leading to both forms of cell death.
Gastrointestinal expression and partial cDNA cloning of murine Muc2
Authors: Van Klinken B. Jan-Willem , Einerhand Alexandra W. C. , Duits Louise A. , Makkink Mireille K. , Tytgat Kristien M. A. J. , Renes Ingrid B. , Verburg Melissa , Büller Hans A. , Dekker Jan
Published: December 2017

To help us investigate the role of mucin in the protection of the colonic epithelium in the mouse, we aimed to identify the murine colonic mucin (MCM) and its encoding gene. We isolated MCM, raised an anti-MCM antiserum, and studied the biosynthesis of MCM in the gastrointestinal tract. Isolated MCM resembled other mucins in physicochemical properties. Anti-MCM recognized MCM as well as rat and human MUC2 on Western blots, interacting primarily with peptide epitopes, indicating that MCM was identical to murine Muc2. Using anti-MCM and previously characterized anti-human and anti-rat MUC2 antibodies, we identified a murine Muc2 precursor in the colon of ∼600 kDa, which appeared similar in size to rat and human MUC2 precursors. Western blotting, immunoprecipitation of metabolically labeled mucins, and immunohistochemistry showed that murine Muc2 was expressed in the colon and the small intestine but was absent in the stomach. To independently identify murine Muc2, we cloned a cDNA fragment from murine colonic mRNA, encoding the 302 NH2-terminal amino acids of murine Muc2. The NH2terminus of murine Muc2 showed 86 and 75% identity to the corresponding rat and human MUC2 peptide sequences, respectively. Northern blotting with a murine Muc2 cDNA probe showed hybridization to a very large mRNA, which was expressed highly in the colon and to some extend in the small intestine but was absent in the stomach. In situ hybridization showed that the murine Muc2 mRNA was confined to intestinal goblet cells. In conclusion, by two independent sets of experiments we identified murine Muc2, which appears homologous to rat and human MUC2. Because Muc2 is prominently expressed in the colon, it is most likely to be the predominant mucin in the colonic mucus layer.
Corticosteroids reverse the inhibition of Na-glucose cotransport in the chronically inflamed rabbit ileum
Authors: Sundaram Uma , Coon Steve , Wisel Sheik , West A. Brian
Published: December 2017

In a rabbit model of chronic ileal inflammation, we previously demonstrated inhibition of Na-glucose cotransport (SGLT-1). The mechanism of inhibition was secondary to a decrease in the number of cotransporters and not solely secondary to an inhibition of Na-K-ATPase or altered affinity for glucose. In this study, we determined the effect of methylprednisolone (MP) on SGLT-1 inhibition during chronic ileitis. Treatment with MP almost completely reversed the reduction in SGLT-1 in villus cells from the chronically inflamed ileum. MP also reversed the decrease in Na-K-ATPase activity in villus cells during chronic ileitis. However, MP treatment reversed the SGLT-1 inhibition in villus cell brush-border membrane vesicles from the inflamed ileum, which suggested an effect of MP at the level of the cotransporter itself. Kinetic studies demonstrated that the reversal of SGLT-1 inhibition by MP was secondary to an increase in the maximal velocity for glucose without a change in the affinity. Analysis of immunoreactive protein levels of the cotransporter demonstrated a restoration of the cotransporter numbers after MP treatment in the chronically inflamed ileum. Thus MP treatment alleviates SGLT-1 inhibition in the chronically inflamed ileum by increasing the number of cotransporters and not solely secondary to enhancing the activity of Na-K-ATPase or by altering the affinity for glucose.
IV. Wilson’s disease and Menkes disease
Authors: Schaefer Mark , Gitlin Jonathan D.
Published: December 2017

Copper is an essential transition metal that permits the facile transfer of electrons in a series of critical biochemical pathways. Menkes disease and Wilson’s disease are inherited disorders of copper metabolism resulting from the absence or dysfunction of homologous copper-transporting ATPases that reside in the trans-Golgi network of all cells. Despite striking differences in the clinical presentation of these two diseases, the respective ATPases function in precisely the same manner within the cell and the unique clinical features of each disease are entirely the result of the tissue-specific expression of each protein. Elucidation of the basic defect in these rare genetic disorders has provided a valuable heuristic paradigm for understanding the mechanisms of cellular copper homeostasis.
Differentiation of mouth versus gut as site of origin of odoriferous breath gases after garlic ingestion
Authors: Suarez F. , Springfield J. , Furne J. , Levitt M.
Published: December 2017

Utilizing the sulfur-containing gases of garlic as probes, we investigated the gut versus mouth origin of odoriferous breath gases. Five individuals ingested 6 g of garlic, and sulfur gases in mouth, alveolar air, and urine samples were measured. The mouth normally contained low concentrations of hydrogen sulfide, methanethiol, and dimethyl sulfide. Immediately after garlic ingestion, transient high concentrations of methanethiol and allyl mercaptan and lesser concentrations of allyl methyl sulfide (AMS), allyl methyl disulfide, and allyl disulfide were observed. With the exception of AMS, all gases were present in far greater concentrations in mouth than alveolar air, indicating an oral origin. Only AMS was of gut origin as evidenced by similar partial pressures in mouth, alveolar air, and urine. After 3 h, AMS was the predominant breath sulfur gas. The unique derivation of AMS from the gut is attributable to the lack of gut and liver metabolism of this gas versus the rapid metabolism of the other gases. Breath odor after garlic ingestion initially originates from the mouth and subsequently from the gut.
Polyspecific substrate uptake by the hepatic organic anion transporter Oatp1 in stably transfected CHO cells
Authors: Eckhardt Uta , Schroeder Alice , Stieger Bruno , Höchli Mathias , Landmann Lukas , Tynes Ronald , Meier Peter J. , Hagenbuch Bruno
Published: December 2017

The rat liver organic anion transporting polypeptide (Oatp1) has been extensively characterized mainly in the Xenopus laevis expression system as a polyspecific carrier transporting organic anions (bile salts), neutral compounds, and even organic cations. In this study, we extended this characterization using a mammalian expression system and confirm the basolateral hepatic expression of Oatp1 with a new antibody. Besides sulfobromophthalein [Michaelis-Menten constant ( K m) of ∼3 μM], taurocholate ( K m of ∼32 μM), and estradiol- 17β-glucuronide ( K m of ∼4 μM), substrates previously shown to be transported by Oatp1 in transfected HeLa cells, we determined the kinetic parameters for cholate ( K m of ∼54 μM), glycocholate ( K m of ∼54 μM), estrone-3-sulfate ( K m of ∼11 μM), CRC-220 ( K m of ∼57 μM), ouabain ( K m of ∼3,000 μM), and ochratoxin A ( K m of ∼29 μM) in stably transfected Chinese hamster ovary (CHO) cells. In addition, three new substrates, taurochenodeoxycholate ( K m of ∼7 μM), tauroursodeoxycholate ( K m of ∼13 μM), and dehydroepiandrosterone sulfate ( K m of ∼5 μM), were also investigated. The results establish the polyspecific nature of Oatp1 in a mammalian expression system and definitely identify conjugated dihydroxy bile salts and steroid conjugates as high-affinity endogenous substrates of Oatp1.
Probiotics inhibit enteropathogenicE. coliadherence in vitro by inducing intestinal mucin gene expression
Authors: Mack David R. , Michail Sonia , Wei Shu , McDougall Laura , Hollingsworth Michael A.
Published: December 2017

Probiotic agents, live microorganisms with beneficial effects for the host, may offer an alternative to conventional antimicrobials in the treatment and prevention of enteric infections. The probiotic agents Lactobacillus plantarum 299v and Lactobacillus rhamnosus GG quantitatively inhibited the adherence of an attaching and effacing pathogenic Escherichia coli to HT-29 intestinal epithelial cells but did not inhibit adherence to nonintestinal HEp-2 cells. HT-29 cells were grown under conditions that induced high levels of either MUC2 or MUC3 mRNA, but HEp-2 cells expressed only minimal levels of MUC2 and no MUC3 mRNA. Media enriched for MUC2 and MUC3 mucin were added exogenously to binding assays and were shown to be capable of inhibiting enteropathogen adherence to HEp-2 cells. Incubation of L. plantarum 299v with HT-29 cells increased MUC2 and MUC3 mRNA expression levels. From these in vitro studies, we propose the hypothesis that the ability of probiotic agents to inhibit adherence of attaching and effacing organisms to intestinal epithelial cells is mediated through their ability to increase expression of MUC2 and MUC3 intestinal mucins.