Paneth cells, antimicrobial peptides and maintenance of intestinal homeostasis.

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Bevins, Charles L; Salzman, Nita H

2011-05-01

Building and maintaining a homeostatic relationship between a host and its colonizing microbiota entails ongoing complex interactions between the host and the microorganisms. The mucosal immune system, including epithelial cells, plays an essential part in negotiating this equilibrium. Paneth cells (specialized cells in the epithelium of the small intestine) are an important source of antimicrobial peptides in the intestine. These cells have become the focus of investigations that explore the mechanisms of host-microorganism homeostasis in the small intestine and its collapse in the processes of infection and chronic inflammation. In this Review, we provide an overview of the intestinal microbiota and describe the cell biology of Paneth cells, emphasizing the composition of their secretions and the roles of these cells in intestinal host defence and homeostasis. We also highlight the implications of Paneth cell dysfunction in susceptibility to chronic inflammatory bowel disease.

Glucagon-like peptide-2 induces rapid digestive adaptation following intestinal resection in preterm neonates

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Short bowel syndrome (SBS) is a frequent complication after intestinal resection in infants suffering from intestinal disease. We tested whether treatment with the intestinotrophic hormone glucagon-like peptide-2 (GLP-2) increases intestinal volume and function in the period immediately following in...

A role for antimicrobial peptides in intestinal microsporidiosis

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Leitch, Gordon J.; Ceballos, Carolina

2009-01-01

SUMMARY Clinical isolates from three microsporidia species, Encephalitozoon intestinalis and Encephalitozoon hellem, and the insect parasite Anncaliia (Brachiola, Nosema) algerae, were used in spore germination and enterocyte-like (C2Bbe1) cell infection assays to determine the effect of a panel of antimicrobial peptides. Spores were incubated with lactoferrin (Lf), lysozyme (Lz), and human beta defensin 2 (HBD2), human alpha defensin 5 (HD5), and human alpha defensin 1 (HNP1), alone and in combination with Lz, prior to germination. Of the Encephalitozoon species only E. hellem spore germination was inhibited by HNP1, while A. algerae spore germination was inhibited by Lf, HBD2, HD5 and HNP1, although HBD2 and HD5 inhibition required the presence of Lz. The effects of HBD2 and HD5 on microsporidia enterocyte infection paralleled their effects on spore germination. Lysozyme alone only inhibited infection with A. algerae, while Lf inhibited infection by E. intestinalis and A. algerae. HNP1 significantly reduced enterocyte infection by all three parasite species and a combination of Lf, Lz and HNP1 caused a further reduced infection with A. algerae. These data suggest that intestinal antimicrobial peptides contribute to the defense of the intestine against infection by luminal microsporidia spores and may partially determine which parasite species infects the intestine. PMID:19079820

Nutrient-intake-level-dependent regulation of intestinal development in newborn intrauterine growth-restricted piglets via glucagon-like peptide-2.

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Liu, J; Liu, Z; Gao, L; Chen, L; Zhang, H

2016-10-01

The objective of the present study was to investigate the intestinal development of newborn intrauterine growth-restricted (IUGR) piglets subjected to normal nutrient intake (NNI) or restricted nutrient intake (RNI). Newborn normal birth weight (NBW) and IUGR piglets were allotted to NNI or RNI levels for 4 weeks from day 8 postnatal. IUGR piglets receiving NNI had similar growth performance compared with that of NBW piglets. Small intestine length and villous height were greater in IUGR piglets fed the NNI than that of piglets fed the RNI. Lactase activity was increased in piglets fed the NNI compared with piglets fed the RNI. Absorptive function, represented by active glucose transport by the Ussing chamber method and messenger RNA (mRNA) expressions of two main intestinal glucose transporters, Na+-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2), were greater in IUGR piglets fed the NNI compared with piglets fed the RNI regimen. The apoptotic process, characterized by caspase-3 activity (a sign of activated apoptotic cells) and mRNA expressions of p53 (pro-apoptotic), bcl-2-like protein 4 (Bax) (pro-apoptotic) and B-cell lymphoma-2 (Bcl-2) (anti-apoptotic), were improved in IUGR piglets fed the NNI regimen. To test the hypothesis that improvements in intestinal development of IUGR piglets fed NNI might be mediated through circulating glucagon-like peptide-2 (GLP-2), GLP-2 was injected subcutaneously to IUGR piglets fed the RNI from day 8 to day 15 postnatal. Although the intestinal development of IUGR piglets fed the RNI regimen was suppressed compared with those fed the NNI regimen, an exogenous injection of GLP-2 was able to bring intestinal development to similar levels as NNI-fed IUGR piglets. Collectively, our results demonstrate that IUGR neonates that have NNI levels could improve intestinal function via the regulation of GLP-2.

β-Klotho as a Negative Regulator of the Peptide Transporters PEPT1 and PEPT2

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Abeer Abousaab

2016-12-01

Full Text Available Background/Aims: β-Klotho, a transmembrane protein expressed in several tissues including the brain and the kidney, is critically important for inhibition of 1,25(OH2D3 formation by FGF23. The extracellular domain of Klotho protein could be cleaved off, thus being released into blood or cerebrospinal fluid. Soluble klotho is a β-glucuronidase participating in the regulation of several ion channels and carriers. The present study explored the effect of β-Klotho protein on the peptide transporters PEPT1 and PEPT2. Methods: cRNA encoding PEPT1 or PEPT2 was injected into Xenopus laevis oocytes and glycine-glycine (2 mM-induced inward current (IGly taken as measure of glycine-glycine transport. Measurements were made without or with prior 24 h treatment with soluble β-Klotho protein (30 ng/ml in the absence and presence of β-glucuronidase inhibitor D-saccharic acid 1,4-lactone monohydrate (DSAL,10 µM. Ussing chamber experiments were employed to determine electrogenic peptide transport across intestinal epithelia of klotho deficient (kl-/- and corresponding wild type (kl+/+ mice. Results: IGly was observed in PEPT1 and in PEPT2 expressing oocytes but not in water injected oocytes. In both, PEPT1 and PEPT2 expressing oocytes IGly was significantly decreased by treatment with soluble β-Klotho protein. As shown for PEPT1, β-klotho protein decreased significantly the maximal transport rate without significantly modifying the affinity of the carrier. The effect of β-Klotho on PEPT1 was reversed by DSAL. Intestinal IGly was significantly larger in kl-/- than in kl+/+ mice. Conclusion: β-Klotho participates in the regulation of the peptide transporters PEPT1 and PEPT2.

Effects of exogenous glucagon-like peptide-2 and distal bowel resection on intestinal and systemic adaptive responses in rats.

Science.gov (United States)

Lai, Sarah W; de Heuvel, Elaine; Wallace, Laurie E; Hartmann, Bolette; Holst, Jens J; Brindle, Mary E; Chelikani, Prasanth K; Sigalet, David L

2017-01-01

To determine the effects of exogenous glucagon-like peptide-2 (GLP-2), with or without massive distal bowel resection, on adaptation of jejunal mucosa, enteric neurons, gut hormones and tissue reserves in rats. GLP-2 is a gut hormone known to be trophic for small bowel mucosa, and to mimic intestinal adaptation in short bowel syndrome (SBS). However, the effects of exogenous GLP-2 and SBS on enteric neurons are unclear. Sprague Dawley rats were randomized to four treatments: Transected Bowel (TB) (n = 8), TB + GLP-2 (2.5 nmol/kg/h, n = 8), SBS (n = 5), or SBS + GLP-2 (2.5 nmol/kg/h, n = 9). SBS groups underwent a 60% jejunoileal resection with cecectomy and jejunocolic anastomosis. All rats were maintained on parenteral nutrition for 7 d. Parameters measured included gut morphometry, qPCR for hexose transporter (SGLT-1, GLUT-2, GLUT-5) and GLP-2 receptor mRNA, whole mount immunohistochemistry for neurons (HuC/D, VIP, nNOS), plasma glucose, gut hormones, and body composition. Resection increased the proportion of nNOS immunopositive myenteric neurons, intestinal muscularis propria thickness and crypt cell proliferation, which were not recapitulated by GLP-2 therapy. Exogenous GLP-2 increased jejunal mucosal surface area without affecting enteric VIP or nNOS neuronal immunopositivity, attenuated resection-induced reductions in jejunal hexose transporter abundance (SGLT-1, GLUT-2), increased plasma amylin and decreased peptide YY concentrations. Exogenous GLP-2 attenuated resection-induced increases in blood glucose and body fat loss. Exogenous GLP-2 stimulates jejunal adaptation independent of enteric neuronal VIP or nNOS changes, and has divergent effects on plasma amylin and peptide YY concentrations. The novel ability of exogenous GLP-2 to modulate resection-induced changes in peripheral glucose and lipid reserves may be important in understanding the whole-body response following intestinal resection, and is worthy of further study.

Vasoactive intestinal peptide is a local mediator in a gut-brain neural axis activating intestinal gluconeogenesis.

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De Vadder, F; Plessier, F; Gautier-Stein, A; Mithieux, G

2015-03-01

Intestinal gluconeogenesis (IGN) promotes metabolic benefits through activation of a gut-brain neural axis. However, the local mediator activating gluconeogenic genes in the enterocytes remains unknown. We show that (i) vasoactive intestinal peptide (VIP) signaling through VPAC1 receptor activates the intestinal glucose-6-phosphatase gene in vivo, (ii) the activation of IGN by propionate is counteracted by VPAC1 antagonism, and (iii) VIP-positive intrinsic neurons in the submucosal plexus are increased under the action of propionate. These data support the role of VIP as a local neuromodulator released by intrinsic enteric neurons and responsible for the induction of IGN through a VPAC1 receptor-dependent mechanism in enterocytes. © 2015 John Wiley & Sons Ltd.

Transmembrane transport of peptide type compounds: prospects for oral delivery

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Lipka, E.; Crison, J.; Amidon, G. L.

1996-01-01

Synthesis and delivery of potential therapeutic peptides and peptidomimetic compounds has been the focus of intense research over the last 10 years. While it is widely recognized that numerous limitations apply to oral delivery of peptides, some of the limiting factors have been addressed and their mechanisms elucidated, which has lead to promising strategies. This article will briefly summarize the challenges, results and current approaches of oral peptide delivery and give some insight on future strategies. The barriers determining peptide bioavailability after oral administration are intestinal membrane permability, size limitations, intestinal and hepatic metabolism and in some cases solubility limitations. Poor membrane permeabilities of hydrophilic peptides might be overcome by structurally modifying the compounds, thus increasing their membrane partition characteristics and/or their affinity to carrier proteins. Another approach is the site-specific delivery of the peptide to the most permeable parts of the intestine. The current view on size limitation for oral drug delivery has neglected partition considerations. Recent studies suggest that compounds with a molecular weight up to 4000 might be significantly absorbed, assuming appropriate partition behavior and stability. Metabolism, probably the most significant factor in the absorption fate of peptides, might be controlled by coadministration of competitive enzyme inhibitors, structural modifications and administration of the compound as a well absorbed prodrug that is converted into the therapeutically active agent after its absorption. For some peptides poor solubility might present a limitation to oral absorption, an issue that has been addressed by mechanistically defining and therefore improving formulation parameters. Effective oral peptide delivery requires further development in understanding these complex mechanisms in order to maximize the therapeutic potential of this class of compounds.

Conformational restrictions in ligand binding to the human intestinal di-/tripeptide transporter

DEFF Research Database (Denmark)

Våbenø, Jon; Nielsen, Carsten Uhd; Steffansen, Bente

2005-01-01

The aim of the present study was to develop a computational method aiding the design of dipeptidomimetic pro-moieties targeting the human intestinal di-/tripeptide transporter hPEPT1. First, the conformation in which substrates bind to hPEPT1 (the bioactive conformation) was identified...... to change the peptide backbone conformation (DeltaE(bbone)) from the global energy minimum conformation to the identified bioactive conformation was calculated for 20 hPEPT1 targeted model prodrugs with known K(i) values. Quantitatively, an inverse linear relationship (r(2)=0.81, q(2)=0.80) was obtained...

Oral absorption of peptides and nanoparticles across the human intestine: Opportunities, limitations and studies in human tissues.

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Lundquist, P; Artursson, P

2016-11-15

In this contribution, we review the molecular and physiological barriers to oral delivery of peptides and nanoparticles. We discuss the opportunities and predictivity of various in vitro systems with special emphasis on human intestine in Ussing chambers. First, the molecular constraints to peptide absorption are discussed. Then the physiological barriers to peptide delivery are examined. These include the gastric and intestinal environment, the mucus barrier, tight junctions between epithelial cells, the enterocytes of the intestinal epithelium, and the subepithelial tissue. Recent data from human proteome studies are used to provide information about the protein expression profiles of the different physiological barriers to peptide and nanoparticle absorption. Strategies that have been employed to increase peptide absorption across each of the barriers are discussed. Special consideration is given to attempts at utilizing endogenous transcytotic pathways. To reliably translate in vitro data on peptide or nanoparticle permeability to the in vivo situation in a human subject, the in vitro experimental system needs to realistically capture the central aspects of the mentioned barriers. Therefore, characteristics of common in vitro cell culture systems are discussed and compared to those of human intestinal tissues. Attempts to use the cell and tissue models for in vitro-in vivo extrapolation are reviewed. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Gp96 Peptide Antagonist gp96-II Confers Therapeutic Effects in Murine Intestinal Inflammation

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Claudia A. Nold-Petry

2017-12-01

Full Text Available BackgroundThe expression of heat shock protein gp96 is strongly correlated with the degree of tissue inflammation in ulcerative colitis and Crohn’s disease, thereby leading us to the hypothesis that inhibition of expression via gp96-II peptide prevents intestinal inflammation.MethodsWe employed daily injections of gp96-II peptide in two murine models of intestinal inflammation, the first resulting from five daily injections of IL-12/IL-18, the second via a single intrarectal application of TNBS (2,4,6-trinitrobenzenesulfonic acid. We also assessed the effectiveness of gp96-II peptide in murine and human primary cell culture.ResultsIn the IL-12/IL-18 model, all gp96-II peptide-treated animals survived until day 5, whereas 80% of placebo-injected animals died. gp96-II peptide reduced IL-12/IL-18-induced plasma IFNγ by 89%, IL-1β by 63%, IL-6 by 43% and tumor necrosis factor (TNF by 70% compared to controls. The clinical assessment Disease Activity Index of intestinal inflammation severity was found to be significantly lower in the gp96-II-treated animals when compared to vehicle-injected mice. gp96-II peptide treatment in the TNBS model limited weight loss to 5% on day 7 compared with prednisolone treatment, whereas placebo-treated animals suffered a 20% weight loss. Histological disease severity was reduced equally by prednisolone (by 40% and gp96-II peptide (35%. Mice treated with either gp96-II peptide or prednisolone exhibited improved endoscopic scores compared with vehicle-treated control mice: vascularity, fibrin, granularity, and translucency scores were reduced by up to 49% by prednisolone and by up to 30% by gp96-II peptide. In vitro, gp96-II peptide reduced TLR2-, TLR4- and IL-12/IL-18-induced cytokine expression in murine splenocytes, with declines in constitutive IL-6 (54%, lipopolysaccharide-induced TNF (48%, IL-6 (81% and in Staphylococcus epidermidis-induced TNF (67% and IL-6 (81%, as well as IL-12/IL-18-induced IFNγ (75%. gp

In vitro and in vivo evaluation of a water-in-oil microemulsion system for enhanced peptide intestinal delivery.

Science.gov (United States)

Liu, Dongyun; Kobayashi, Taku; Russo, Steven; Li, Fengling; Plevy, Scott E; Gambling, Todd M; Carson, Johnny L; Mumper, Russell J

2013-01-01

Peptide and protein drugs have become the new generation of therapeutics, yet most of them are only available as injections, and reports on oral local intestinal delivery of peptides and proteins are quite limited. The aim of this work was to develop and evaluate a water-in-oil (w/o) microemulsion system in vitro and in vivo for local intestinal delivery of water-soluble peptides after oral administration. A fluorescent labeled peptide, 5-(and-6)-carboxytetramethylrhodamine labeled HIV transactivator protein TAT (TAMRA-TAT), was used as a model peptide. Water-in-oil microemulsions consisting of Miglyol 812, Capmul MCM, Tween 80, and water were developed and characterized in terms of appearance, viscosity, conductivity, morphology, and particle size analysis. TAMRA-TAT was loaded and its enzymatic stability was assessed in modified simulated intestinal fluid (MSIF) in vitro. In in vivo studies, TAMRA-TAT intestinal distribution was evaluated using fluorescence microscopy after TAMRA-TAT microemulsion, TAMRA-TAT solution, and placebo microemulsion were orally gavaged to mice. The half-life of TAMRA-TAT in microemulsion was enhanced nearly three-fold compared to that in the water solution when challenged by MSIF. The treatment with TAMRA-TAT microemulsion after oral administration resulted in greater fluorescence intensity in all intestine sections (duodenum, jejunum, ileum, and colon) compared to TAMRA-TAT solution or placebo microemulsion. The in vitro and in vivo studies together suggested TAMRA-TAT was better protected in the w/o microemulsion in an enzyme-containing environment, suggesting that the w/o microemulsions developed in this study may serve as a potential delivery vehicle for local intestinal delivery of peptides or proteins after oral administration.

Rotavirus NSP4114-135 peptide has no direct, specific effect on chloride transport in rabbit brush-border membrane

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Vasseur Monique

2006-11-01

Full Text Available Abstract The direct effect of the rotavirus NSP4114-135 and Norovirus NV464-483 peptides on 36Cl uptake was studied by using villus cell brush border membrane (BBM isolated from young rabbits. Both peptides inhibited the Cl-/H+ symport activity about equally and partially. The interaction involved one peptide-binding site per carrier unit. Whereas in vitro NSP4114-135 caused nonspecific inhibition of the Cl-/H+ symporter, the situation in vivo is different. Because rotavirus infection in young rabbits accelerated both Cl- influx and Cl- efflux rates across villi BBM without stimulating Cl- transport in crypt BBM, we conclude that the NSP4114-135 peptide, which causes diarrhea in young rodents, did not have any direct, specific effect on either intestinal absorption or secretion of chloride. The lack of direct effect of NSP4 on chloride transport strengthens the hypothesis that NSP4 would trigger signal transduction pathways to enhance net chloride secretion at the onset of rotavirus diarrhea.

Growth of embryo and gene expression of nutrient transporters in the small intestine of the domestic pigeon (Columba livia)*

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Chen, Ming-xia; Li, Xiang-guang; Yang, Jun-xian; Gao, Chun-qi; Wang, Bin; Wang, Xiu-qi; Yan, Hui-chao

2015-01-01

The objective of this study was to investigate the relationship between gene expression of nutrient (amino acid, peptide, sodium and proton) transporters in the small intestine and embryonic growth in domestic pigeons (Columba livia). One hundred and twenty-five fertilized eggs were randomly assigned into five groups and were incubated under optimal conditions (temperature of 38.1 °C and relative humidity of 55%). Twenty embryos/birds from each group were sacrificed by cervical dislocation on embryonic day (E) 9, 11, 13, 15 and day of hatch (DOH). The eggs, embryos (without yolk sac), and organs (head, brain, heart, liver, lungs, kidney, gizzard, small intestine, legs, and thorax) were dissected, cleaned, and weighed. Small intestine samples were collected for RNA isolation. The mRNA abundance of intestinal nutrient transporters was evaluated by real-time reverse transcription-polymerase chain reaction (RT-PCR). We classified these ten organs into four types according to the changes in relative weight during embryonic development. In addition, the gene expression of nutrient transporters was differentially regulated by embryonic day. The mRNA abundances of b0,+AT, EAAT3, y+LAT2, PepT1, LAT4, NHE2, and NHE3 increased linearly with age, whereas mRNA abundances of CAT1, CAT2, LAT1, EAAT2, SNAT1, and SNAT2 were increased to higher levels on E9 or E11 and then decreased to lower levels until DOH. The results of correlation analysis showed that the gene expressions of b0,+AT, EAAT3, PepT1, LAT4, NHE2, NHE3, and y+LAT2 had positive correlations with body weight (0.71intestinal weight (0.80intestinal weight (−0.84

Growth of embryo and gene expression of nutrient transporters in the small intestine of the domestic pigeon (Columba livia).

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Chen, Ming-xia; Li, Xiang-guang; Yang, Jun-xian; Gao, Chun-qi; Wang, Bin; Wang, Xiu-qi; Yan, Hui-chao

2015-06-01

The objective of this study was to investigate the relationship between gene expression of nutrient (amino acid, peptide, sodium and proton) transporters in the small intestine and embryonic growth in domestic pigeons (Columba livia). One hundred and twenty-five fertilized eggs were randomly assigned into five groups and were incubated under optimal conditions (temperature of 38.1 °C and relative humidity of 55%). Twenty embryos/birds from each group were sacrificed by cervical dislocation on embryonic day (E) 9, 11, 13, 15 and day of hatch (DOH). The eggs, embryos (without yolk sac), and organs (head, brain, heart, liver, lungs, kidney, gizzard, small intestine, legs, and thorax) were dissected, cleaned, and weighed. Small intestine samples were collected for RNA isolation. The mRNA abundance of intestinal nutrient transporters was evaluated by real-time reverse transcription-polymerase chain reaction (RT-PCR). We classified these ten organs into four types according to the changes in relative weight during embryonic development. In addition, the gene expression of nutrient transporters was differentially regulated by embryonic day. The mRNA abundances of b(0,+)AT, EAAT3, y(+)LAT2, PepT1, LAT4, NHE2, and NHE3 increased linearly with age, whereas mRNA abundances of CAT1, CAT2, LAT1, EAAT2, SNAT1, and SNAT2 were increased to higher levels on E9 or E11 and then decreased to lower levels until DOH. The results of correlation analysis showed that the gene expressions of b(0,+)AT, EAAT3, PepT1, LAT4, NHE2, NHE3, and y(+)LAT2 had positive correlations with body weight (0.71intestinal weight (0.80intestinal weight (-0

A pilot study examining the relationship among Crohn disease activity, glucagon-like peptide-2 signalling and intestinal function in pediatric patients

DEFF Research Database (Denmark)

Sigalet, David L; Kravarusic, Dragan; Butzner, Decker

2013-01-01

[± SD] age 15.3 ± 1.3 years) and 10 controls (10.3 ± 1.6 years) were studied. In patients with active disease, fasting levels of GLP-2 remained stable but postprandial levels were reduced. Patients with active disease exhibited reduced glucose absorption and increased lactulose⁄mannitol recovery; all......  BACKGROUND⁄/OBJECTIVES: The relationship between the enteroendocrine hormone glucagon-like peptide 2 (GLP-2) and intestinal inflammation is unclear. GLP-2 promotes mucosal growth, decreases permeability and reduces inflammation in the intestine; physiological stimulation of GLP-2 release...... of the small intestine) with a disease activity index >150. Fasting and postprandial GLP-2 levels and quantitative urinary recovery of orally administered 3-O-methyl-glucose (active transport) and lactulose⁄mannitol (passive) were quantified during the acute and remission phases. RESULTS: Seven patients (mean...

Effects of exogenous glucagon-like peptide-2 and distal bowel resection on intestinal and systemic adaptive responses in rats.

Directory of Open Access Journals (Sweden)

Sarah W Lai

Full Text Available To determine the effects of exogenous glucagon-like peptide-2 (GLP-2, with or without massive distal bowel resection, on adaptation of jejunal mucosa, enteric neurons, gut hormones and tissue reserves in rats.GLP-2 is a gut hormone known to be trophic for small bowel mucosa, and to mimic intestinal adaptation in short bowel syndrome (SBS. However, the effects of exogenous GLP-2 and SBS on enteric neurons are unclear.Sprague Dawley rats were randomized to four treatments: Transected Bowel (TB (n = 8, TB + GLP-2 (2.5 nmol/kg/h, n = 8, SBS (n = 5, or SBS + GLP-2 (2.5 nmol/kg/h, n = 9. SBS groups underwent a 60% jejunoileal resection with cecectomy and jejunocolic anastomosis. All rats were maintained on parenteral nutrition for 7 d. Parameters measured included gut morphometry, qPCR for hexose transporter (SGLT-1, GLUT-2, GLUT-5 and GLP-2 receptor mRNA, whole mount immunohistochemistry for neurons (HuC/D, VIP, nNOS, plasma glucose, gut hormones, and body composition.Resection increased the proportion of nNOS immunopositive myenteric neurons, intestinal muscularis propria thickness and crypt cell proliferation, which were not recapitulated by GLP-2 therapy. Exogenous GLP-2 increased jejunal mucosal surface area without affecting enteric VIP or nNOS neuronal immunopositivity, attenuated resection-induced reductions in jejunal hexose transporter abundance (SGLT-1, GLUT-2, increased plasma amylin and decreased peptide YY concentrations. Exogenous GLP-2 attenuated resection-induced increases in blood glucose and body fat loss.Exogenous GLP-2 stimulates jejunal adaptation independent of enteric neuronal VIP or nNOS changes, and has divergent effects on plasma amylin and peptide YY concentrations. The novel ability of exogenous GLP-2 to modulate resection-induced changes in peripheral glucose and lipid reserves may be important in understanding the whole-body response following intestinal resection, and is worthy of further study.

Effects of exogenous glucagon-like peptide-2 and distal bowel resection on intestinal and systemic adaptive responses in rats

Science.gov (United States)

de Heuvel, Elaine; Wallace, Laurie E.; Hartmann, Bolette; Holst, Jens J.; Brindle, Mary E.; Chelikani, Prasanth K.; Sigalet, David L.

2017-01-01

Objective To determine the effects of exogenous glucagon-like peptide-2 (GLP-2), with or without massive distal bowel resection, on adaptation of jejunal mucosa, enteric neurons, gut hormones and tissue reserves in rats. Background GLP-2 is a gut hormone known to be trophic for small bowel mucosa, and to mimic intestinal adaptation in short bowel syndrome (SBS). However, the effects of exogenous GLP-2 and SBS on enteric neurons are unclear. Methods Sprague Dawley rats were randomized to four treatments: Transected Bowel (TB) (n = 8), TB + GLP-2 (2.5 nmol/kg/h, n = 8), SBS (n = 5), or SBS + GLP-2 (2.5 nmol/kg/h, n = 9). SBS groups underwent a 60% jejunoileal resection with cecectomy and jejunocolic anastomosis. All rats were maintained on parenteral nutrition for 7 d. Parameters measured included gut morphometry, qPCR for hexose transporter (SGLT-1, GLUT-2, GLUT-5) and GLP-2 receptor mRNA, whole mount immunohistochemistry for neurons (HuC/D, VIP, nNOS), plasma glucose, gut hormones, and body composition. Results Resection increased the proportion of nNOS immunopositive myenteric neurons, intestinal muscularis propria thickness and crypt cell proliferation, which were not recapitulated by GLP-2 therapy. Exogenous GLP-2 increased jejunal mucosal surface area without affecting enteric VIP or nNOS neuronal immunopositivity, attenuated resection-induced reductions in jejunal hexose transporter abundance (SGLT-1, GLUT-2), increased plasma amylin and decreased peptide YY concentrations. Exogenous GLP-2 attenuated resection-induced increases in blood glucose and body fat loss. Conclusions Exogenous GLP-2 stimulates jejunal adaptation independent of enteric neuronal VIP or nNOS changes, and has divergent effects on plasma amylin and peptide YY concentrations. The novel ability of exogenous GLP-2 to modulate resection-induced changes in peripheral glucose and lipid reserves may be important in understanding the whole-body response following intestinal resection, and is worthy

Vasoactive intestinal peptide and electrical activity influence neuronal survival

International Nuclear Information System (INIS)

Brenneman, D.E.; Eiden, L.E.

1986-01-01

Blockage of electrical activity in dissociated spinal cord cultures results in a significant loss of neurons during a critical period in development. Decreases in neuronal cell numbers and 125 I-labeled tetanus toxin fixation produced by electrical blockage with tetrodotoxin (TTX) were prevented by addition of vasoactive intestinal peptide (VIP) to the nutrient medium. The most effective concentration of VIP was 0.1 nM. At higher concentrations, the survival-enhancing effect of VIP on TTX-treated cultures was attenuated. Addition of the peptide alone had no significant effect on neuronal cell counts or tetanus toxin fixation. With the same experimental conditions, two closely related peptides, PHI-27 (peptide, histidyl-isoleucine amide) and secretin, were found not to increase the number of neurons in TTX-treated cultures. Interference with VIP action by VIP antiserum resulted in neuronal losses that were not significantly different from those observed after TTX treatment. These data indicate that under conditions of electrical blockade a neurotrophic action of VIP on neuronal survival can be demonstrated

Glucagon-like peptide 2 treatment may improve intestinal adaptation during weaning

DEFF Research Database (Denmark)

Thymann, Thomas; Le Huërou-Luron, I; Petersen, Y M

2014-01-01

Transition from sow’s milk to solid feed is associated with intestinal atrophy and diarrhea. We hypothesized that the intestinotrophic hormone glucagon-like peptide 2 (GLP-2) would induce a dose- and health status-dependent effect on gut adaptation. In Exp. 1, weaned pigs (average BW at weaning 4...

Water transport through the intestinal epithelial barrier under different osmotic conditions is dependent on LI-cadherin trans-interaction.

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Weth, Agnes; Dippl, Carsten; Striedner, Yasmin; Tiemann-Boege, Irene; Vereshchaga, Yana; Golenhofen, Nikola; Bartelt-Kirbach, Britta; Baumgartner, Werner

2017-04-03

In the intestine water has to be reabsorbed from the chymus across the intestinal epithelium. The osmolarity within the lumen is subjected to high variations meaning that water transport often has to take place against osmotic gradients. It has been hypothesized that LI-cadherin is important in this process by keeping the intercellular cleft narrow facilitating the buildup of an osmotic gradient allowing water reabsorption. LI-cadherin is exceptional among the cadherin superfamily with respect to its localization along the lateral plasma membrane of epithelial cells being excluded from adherens junction. Furthermore it has 7 but not 5 extracellular cadherin repeats (EC1-EC7) and a small cytosolic domain. In this study we identified the peptide VAALD as an inhibitor of LI-cadherin trans-interaction by modeling the structure of LI-cadherin and comparison with the known adhesive interfaces of E-cadherin. This inhibitory peptide was used to measure LI-cadherin dependency of water transport through a monolayer of epithelial CACO2 cells under various osmotic conditions. If LI-cadherin trans-interaction was inhibited by use of the peptide, water transport from the luminal to the basolateral side was impaired and even reversed in the case of hypertonic conditions whereas no effect could be observed at isotonic conditions. These data are in line with a recently published model predicting LI-cadherin to keep the width of the lateral intercellular cleft small. In this narrow cleft a high osmolarity can be achieved due to ion pumps yielding a standing osmotic gradient allowing water absorption from the gut even if the faeces is highly hypertonic.

Enhanced Intestinal Permeability of Bufalin by a Novel Bufalin-Peptide-Dendrimer Inclusion through Caco-2 Cell Monolayer

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Chi-on Chan

2017-11-01

Full Text Available Bufalin (BFL has excellent physiological activities such as defending tumors, improving cardiac function, and so on. However, due to its poor water-solubility and bioavailability, the clinical application of BFL remains limited. In order to improve bioavailability of BFL, in our previous research, a novel peptide-dendrimer (PD was synthesized and applied to encapsulate BFL. In the present study, we investigate the absorption property and mechanism of BFL in free form and BFL-peptide-dendrimer inclusion (BPDI delivery system by using the Caco-2 cell monolayer model in vitro. The apparent permeability coefficient (Papp values of BFL in free or BPDI form were over 1.0 × 10−6 cm/s. Meanwhile, their almost equal bi-directional transport and linear transport percentage with time and concentration course indicated that BFL in both forms was absorbed mainly through passive diffusion. The most important result is that the Papp values of BFL increased about three-fold more BPDI than those of its free form, which indicated the intestinal permeability of BFL could be improved while BFL was encapsulated in BPDI form. Therefore, PD encapsulation may be a potential delivery system to increase the bioavailability of BFL.

Resveratrol Inhibits Porcine Intestinal Glucose and Alanine Transport: Potential Roles of Na+/K+-ATPase Activity, Protein Kinase A, AMP-Activated Protein Kinase and the Association of Selected Nutrient Transport Proteins with Detergent Resistant Membranes

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Stefanie Klinger

2018-03-01

Full Text Available Background: Beneficial effects of Resveratrol (RSV have been demonstrated, including effects on transporters and channels. However, little is known about how RSV influences intestinal transport. The aim of this study was to further characterize the effects of RSV on intestinal transport and the respective mechanisms. Methods: Porcine jejunum and ileum were incubated with RSV (300 µM, 30 min in Ussing chambers (functional studies and tissue bathes (detection of protein expression, phosphorylation, association with detergent resistant membranes (DRMs. Results: RSV reduced alanine and glucose-induced short circuit currents (ΔIsc and influenced forskolin-induced ΔIsc. The phosphorylation of sodium–glucose-linked transporter 1 (SGLT1, AMP-activated protein kinase (AMPK, protein kinase A substrates (PKA-S and liver kinase B1 (LKB1 increased but a causative relation to the inhibitory effects could not directly be established. The DRM association of SGLT1, peptide transporter 1 (PEPT1 and (phosphorylated Na+/H+-exchanger 3 (NHE3 did not change. Conclusion: RSV influences the intestinal transport of glucose, alanine and chloride and is likely to affect other transport processes. As the effects of protein kinase activation vary between the intestinal localizations, it would appear that increasing cyclic adenosine monophosphate (cAMP levels are part of the mechanism. Nonetheless, the physiological responses depend on cell type-specific structures.

Microvillus-Specific Protein Tyrosine Phosphatase SAP-1 Plays a Role in Regulating the Intestinal Paracellular Transport of Macromolecules.

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Mori, Shingo; Kamei, Noriyasu; Murata, Yoji; Takayama, Kozo; Matozaki, Takashi; Takeda-Morishita, Mariko

2017-09-01

The stomach cancer-associated protein tyrosine phosphatase 1 (SAP-1) is a receptor-type protein tyrosine phosphatase that is specifically expressed on the apical membrane of the intestinal epithelium. SAP-1 is known to maintain the balance of phosphorylation of proteins together with protein kinases; however, its biological function and impact on pharmacokinetics in the intestine remain unclear. The present study, therefore, aimed at clarifying the relationship between SAP-1 and the intestinal absorption behaviors of typical transporter substrates and macromolecules. The endogenous levels of glucose and total cholesterol in the blood were similar between wild-type and SAP-1-deficient mice (Sap1 -/- ), suggesting no contribution of SAP-1 to biogenic influx. Moreover, in vitro transport study with everted ileal sacs demonstrated that there was no difference in the absorption of breast cancer resistance protein, P-glycoprotein, and peptide transporter substrates between both mice. However, absorptive clearance of macromolecular model dextrans (FD-4 and FD-10) in Sap1 -/- mice was significantly higher than that in wild-type mice, and this was confirmed by the trend of increased FD-4 absorption from colonic loops of Sap1 -/- mice. Therefore, the results of this study suggest the partial contribution of SAP-1 to the regulated transport of hydrophilic macromolecules through paracellular tight junctions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Di/tri-peptide transporters as drug delivery targets

DEFF Research Database (Denmark)

Nielsen, C U; Brodin, Birger

2003-01-01

-dependent, and the transporters thus belong to the Proton-dependent Oligopeptide Transporter (POT)-family. The transporters are not drug targets per se, however due to their uniquely broad substrate specificity; they have proved to be relevant drug targets at the level of drug transport. Drug molecules such as oral active beta....../tri-peptide transporters from vesicular storages 3) changes in gene transcription/mRNA stability. The aim of the present review is to discuss physiological, patho-physiological and drug-induced regulation of di/tri-peptide transporter mediated transport....

Vasoactive intestinal polypeptide and other preprovasoactive intestinal polypeptide-derived peptides in the female and male genital tract: localization, biosynthesis, and functional and clinical significance

DEFF Research Database (Denmark)

Ottesen, B; Fahrenkrug, J

1995-01-01

Vasoactive intestinal polypeptide, a neuropeptide with wide distribution in the central and peripheral nervous system, has a broad spectrum of biologic actions. The demonstration of vasoactive intestinal polypeptide containing nerve fibers within the female and male genital tract 17 years ago...... indicated a putative role for this peptide in the local nervous control of reproductive functions. The genes encoding the preprovasoactive intestinal polypeptide precursor molecule and the vasoactive intestinal polypeptide receptor have been identified. The gene expression has been studied by the use...... in the genital tracts (i.e., blood flow and nonvascular smooth muscle relaxation). In the ovary vasoactive intestinal polypeptide seems to play an important role as regulator and/or modulator of folliculogenesis and steroidogenesis. In the male genital tract vasoactive intestinal polypeptide seems to participate...

Charge Transport Phenomena in Peptide Molecular Junctions

International Nuclear Information System (INIS)

Luchini, A.; Petricoin, E.F.; Geho, D.H.; Liotta, L.A.; Long, D.P.; Vaisman, I.I.

2008-01-01

Inelastic electron tunneling spectroscopy (IETS) is a valuable in situ spectroscopic analysis technique that provides a direct portrait of the electron transport properties of a molecular species. In the past, IETS has been applied to small molecules. Using self-assembled nano electronic junctions, IETS was performed for the first time on a large polypeptide protein peptide in the phosphorylated and native form, yielding interpretable spectra. A reproducible 10-fold shift of the I/V characteristics of the peptide was observed upon phosphorylation. Phosphorylation can be utilized as a site-specific modification to alter peptide structure and thereby influence electron transport in peptide molecular junctions. It is envisioned that kinases and phosphatases may be used to create tunable systems for molecular electronics applications, such as biosensors and memory devices.

Bioavailability and transport of peptides and peptide drugs into the brain.

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Egleton, R D; Davis, T P

1997-01-01

Rational drug design and the targeting of specific organs has become a reality in modern drug development, with the emergence of molecular biology and receptor chemistry as powerful tools for the pharmacologist. A greater understanding of peptide function as one of the major extracellular message systems has made neuropeptides an important target in neuropharmaceutical drug design. The major obstacle to targeting the brain with therapeutics is the presence of the blood-brain barrier (BBB), which controls the concentration and entry of solutes into the central nervous system. Peptides are generally polar in nature, do not easily cross the blood-brain barrier by diffusion, and except for a small number do not have specific transport systems. Peptides can also undergo metabolic deactivation by peptidases of the blood, brain and the endothelial cells that comprise the BBB. In this review, we discuss a number of the recent strategies which have been used to promote peptide stability and peptide entry into the brain. In addition, we approach the subject of targeting specific transport systems that can be found on the brain endothelial cells, and describe the limitations of the methodologies that are currently used to study brain entry of neuropharmaceuticals.

Intestinal glucose transport and salinity adaptation in a euryhaline teleost

International Nuclear Information System (INIS)

Reshkin, S.J.; Ahearn, G.A.

1987-01-01

Glucose transport by upper and lower intestinal brush-border membrane vesicles of the African tilapia (Oreochromis mossambicus) was characterized in fish acclimated to either freshwater of full-strength sea water. D-[ 3 H]-glucose uptake by vesicles was stimulated by a transmembrane Na gradient, was electrogenic, and was enhanced by countertransport of either D-glucose or D-galactose. Glucose transport was greater in the upper intestine than in the lower intestine and in sea water animals rather than in fish acclimated to freshwater. Glucose influx (10-s uptake) involved both saturable and nonsaturable transport components. Sea water adaptation increased apparent glucose influx K/sub t/, J/sub max/, apparent diffusional permeability (P), and the apparent Na affinity of the cotransport system in both intestinal segments, but the stoichiometry of Na-glucose transfer (1:1) was unaffected by differential saline conditions or gut region. It is suggested that increased sugar transport in sea water animals is due to the combination of enhanced Na-binding properties and an increase in number or transfer rate of the transport proteins. Freshwater animals compensate for reduced Na affinity of the coupled process by markedly increasing the protein affinity for glucose

Vitamin D and intestinal calcium transport after bariatric surgery.

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Schafer, Anne L

2017-10-01

Bariatric surgery is a highly effective treatment for obesity, but it may have detrimental effects on the skeleton. Skeletal effects are multifactorial but mediated in part by nutrient malabsorption. While there is increasing interest in non-nutritional mechanisms such as changes in fat-derived and gut-derived hormones, nutritional factors are modifiable and thus represent potential opportunities to prevent and treat skeletal complications. This review begins with a discussion of normal intestinal calcium transport, including recent advances in our understanding of its regulation by vitamin D, and areas of continued uncertainty. Human and animal studies of vitamin D and intestinal calcium transport after bariatric surgery are then summarized. In humans, even with optimized 25-hydroxyvitamin D levels and recommended calcium intake, fractional calcium absorption decreased dramatically after Roux-en-Y gastric bypass (RYGB). In rats, intestinal calcium absorption was lower after RYGB than after sham surgery, despite elevated 1,25-dihyroxyvitamin D levels and intestinal gene expression evidence of vitamin D responsiveness. Such studies have the potential to shed new light on the physiology of vitamin D and intestinal calcium transport. Moreover, understanding the effects of bariatric surgery on these processes may improve the clinical care of bariatric surgery patients. Published by Elsevier Ltd.

Carrier-mediated transport of peptides by the kidney

International Nuclear Information System (INIS)

Skopicki, H.A.

1988-01-01

Small peptide transport was characterized to determine if: (1) Multiple carriers are present in the luminal membrane of renal proximal tubular cells; (2) Carrier-mediated peptide transport is limited by size; and (3) Gentamicin inhibits carrier-mediated reabsorption of peptides. Uptake of glycyl-[ 3 H]proline (Gly-Pro) into renal brush border membrane vesicles demonstrated a dual affinity carrier system. Whether multiple carriers are present was further investigated by characterizing the uptake of [ 3 H]pyroglutamyl-histidine. To determine if carrier-mediated transport of peptides is limited by size of the molecule, uptake of the hydrolytically resistant tripeptide, [ 3 H]pryroglutamyl-histidyl-tryptophan (pGlu-His-Trp), and tetrapeptide, [ 3 H]pyroglutamyl-histidyl-tryptophyl-serine (pGlu-His-Trp-Ser) were assessed. These data indicate: multiple carriers exist on the luminal membrane of renal proximal tubular cells for the transport of dipeptides, and tripeptide pGlu-His-Trp and the tetrapeptide pGlu-His-Trp-Ser are not taken up by a carrier-mediated mechanism, suggesting that the carrier may be limited by the size of the substrate

Interaction of Drug or Food with Drug Transporters in Intestine and Liver.

Science.gov (United States)

Nakanishi, Takeo; Tamai, Ikumi

2015-01-01

Oral bioavailability (F) is determined as fraction of the drug dose absorbed through the gastrointestinal membranes (Fa), the unmetabolized fraction of the absorbed dose that passes through the gut into the portal blood (Fg), and the hepatic first pass availability (Fh), namely F is expressed as the product of Fa, Fg and Fh (F = Fa.Fg.Fh). Current evidence suggests that transporter proteins play a role in intestinal absorption and hepatobiliary clearance of drugs. Among those transporters, this review will focus on PEPT1 and OATP2B1 as influx transporter and p-glycoprotein (P-gp) and BCRP as efflux transporter in intestinal epithelial cells, and on OATP1B1 and 1B3 as influx transporter and MRP2 as efflux transporter in hepatocytes, respectively, because drug-drug (DDI) and -food (DFI) interactions on these transporter are considered to affect bioavailability of their substrate drugs. DDI and DFI may reduce systemic exposure to drug by blocking influx transporters in intestine, but increase it by modulating influx and efflux transporters in liver and efflux transporters in intestines. Namely, drug disposition and efficacy are likely affected by DDI and DFI, resulting in treatment failures or increase in adverse effect. Therefore, it is of significantly importance to understand precise mechanism of DDI and DFI. This review will present information about transporter-based DDI and DFI in the processes of intestinal absorption and hepatic clearance of drugs, and discuss about their clinical implication.

Acylation of salmon calcitonin modulates in vitro intestinal peptide flux through membrane permeability enhancement

DEFF Research Database (Denmark)

Trier, Sofie; Linderoth, Lars; Bjerregaard, Simon

2015-01-01

hypothesize that tailoring the acylation may be used to optimize intestinal translocation. This work aims to characterize acylated analogues of the therapeutic peptide salmon calcitonin (sCT), which lowers blood calcium, by systematically increasing acyl chain length at two positions, in order to elucidate...... to be optimal, as elongating the chain causes greater binding to the cell membrane but similar permeability, and we speculate that increasing the chain length further may decrease the permeability. In conclusion, acylated sCT acts as its own in vitro intestinal permeation enhancer, with reversible effects...... on Caco-2 cells, indicating that acylation of sCT may represent a promising tool to increase intestinal permeability without adding oral permeation enhancers....

Protein Restriction with Amino Acid-Balanced Diets Shrinks Circulating Pool Size of Amino Acid by Decreasing Expression of Specific Transporters in the Small Intestine.

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Kai Qiu

Full Text Available Dietary protein restriction is not only beneficial to health and longevity in humans, but also protects against air pollution and minimizes feeding cost in livestock production. However, its impact on amino acid (AA absorption and metabolism is not quite understood. Therefore, the study aimed to explore the effect of protein restriction on nitrogen balance, circulating AA pool size, and AA absorption using a pig model. In Exp.1, 72 gilts weighting 29.9 ± 1.5 kg were allocated to 1 of the 3 diets containing 14, 16, or 18% CP for a 28-d trial. Growth (n = 24, nitrogen balance (n = 6, and the expression of small intestinal AA and peptide transporters (n = 6 were evaluated. In Exp.2, 12 barrows weighting 22.7 ± 1.3 kg were surgically fitted with catheters in the portal and jejunal veins as well as the carotid artery and assigned to a diet containing 14 or 18% CP. A series of blood samples were collected before and after feeding for determining the pool size of circulating AA and AA absorption in the portal vein, respectively. Protein restriction did not sacrifice body weight gain and protein retention, since nitrogen digestibility was increased as dietary protein content reduced. However, the pool size of circulating AA except for lysine and threonine, and most AA flux through the portal vein were reduced in pigs fed the low protein diet. Meanwhile, the expression of peptide transporter 1 (PepT-1 was stimulated, but the expression of the neutral and cationic AA transporter systems was depressed. These results evidenced that protein restriction with essential AA-balanced diets, decreased AA absorption and reduced circulating AA pool size. Increased expression of small intestinal peptide transporter PepT-1 could not compensate for the depressed expression of jejunal AA transporters for AA absorption.

Functional characterization of folic acid transport in the intestine of the laying hen using the everted intestinal sac model.

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Tactacan, G B; Rodriguez-Lecompte, J C; Karmin, O; House, J D

2011-01-01

Absorption at the level of the intestine is likely a primary regulatory mechanism for the deposition of dietary supplemented folic acid into the chicken egg. Therefore, factors affecting the intestinal transport of folic acid in the laying hen may influence the level of egg folate concentrations. To this end, a series of experiments using intestinal everted sacs were conducted to characterize intestinal folic acid absorption processes in laying hens. Effects of naturally occurring folate derivatives (5-methyl and 10-formyltetrahydrofolate) as well as heme on folic acid absorption were also investigated. Folic acid absorption was measured based on the rate of uptake of (3)H-labeled folic acid in the everted sac from various segments of the small and large intestines. Folic acid concentration, incubation length, and pH condition were optimized before the performance of uptake experiments. The distribution profile of folic acid transport along the intestine was highest in the upper half of the small intestine. Maximum uptake rate (nmol·100 g tissue(-1)·min(-1)) was observed in the duodenum (20.6 ± 1.9) and jejunum (22.3 ± 2.0) and decreased significantly in the ileum (15.3 ± 1.1) and cecum (9.3 ± 0.9). Transport increased proportionately (P methyl and 10-formyltetrahydrofolate as well as heme impeded folic acid uptake, reducing intestinal folic acid absorption when added at concentrations ranging from 0 to 100 µM. Overall, these data indicated the presence of a folic acid transport system in the entire intestine of the laying hen. Uptake of folic acid in the cecum raises the likelihood of absorption of bacterial-derived folate.

Intestinal transport and metabolism of acrylamide

International Nuclear Information System (INIS)

Zoedl, Bettina; Schmid, Diethart; Wassler, Georg; Gundacker, Claudia; Leibetseder, Valentin; Thalhammer, Theresia; Ekmekcioglu, Cem

2007-01-01

There has been an intensive debate whether dietary exposure to acrylamide could increase the risk of human cancer since the first description of the presence of acrylamide in food in 2002. As the intestinal mechanisms of acrylamide absorption are poorly investigated we studied the transport of acrylamide in differentiated Caco-2 cells and its effects on biotransformation enzymes (CYP2E1 and glutathione S-transferase) and glutathione levels. We found that the apparent permeability of [1- 14 C] acrylamide from the basal to the apical compartment was approximately 20% higher compared to that in the opposite direction. No differences were detected for apical-basal transport against a basal gradient. Transport rates from the apical to the basal chamber at 4 deg. C were about 50% lower than at 37 deg. C. Concentration dependent transport from apical to basal was linear. Predominantly, basal to apical transport was decreased when energy metabolism of the cells was inhibited by application of sodium azide and 2-deoxy-D-glucose. Finally, more acrylamide was transported at luminal pH 6 compared to pH 7.4 from basal to the apical direction. Increasing levels of acrylamide showed no effects on the activity of glutathione S-transferase but resulted in a depletion of total glutathione concentrations. In conclusion transport of acrylamide in the intestine is mediated primarily by passive processes possibly combined with a modest energy- and pH-dependent active secretory component. Depletion of cellular glutathione levels may be one potential mechanism for acrylamide (geno)toxicity

Neuropeptide Y-like immunoreactivity in rat cranial parasympathetic neurons: coexistence with vasoactive intestinal peptide and choline acetyltransferase

International Nuclear Information System (INIS)

Leblanc, G.C.; Trimmer, B.A.; Landis, S.C.

1987-01-01

Neuropeptide Y (NPY) is widely distributed in the sympathetic nervous system, where it is colocalized with norepinephrine. The authors report here that NPY-immunoreactive neurons are also abundant in three cranial parasympathetic ganglia, the otic, sphenopalatine, and ciliary, in the rat measured by radioimmunoassay. High-performance liquid chromatographic analysis of the immunoreactive material present in the otic ganglion indicates that this material is very similar to porcine NPY and indistinguishable from the NPY-like immunoreactivity present in rat sympathetic neurons. These findings raise the possibility that NPY acts as a neuromodulator in the parasympathetic as well as the sympathetic nervous system. In contrast to what had been observed for sympathetic neurons, NPY-immunoreactive neurons in cranial parasympathetic ganglia do not contain detectable catecholamines or tyrosine hydroxylase immunoreactivity, and many do contain immunoreactivity for vasoactive intestinal peptide and/or choline acetyltransferase. These findings suggest that there is no simple rule governing coexpression of NPY with norepinephrine, acetylcholine, or vasoactive intestinal peptide in autonomic neurons. Further, while functional studies have indicated that NPY exerts actions on the peripheral vasculature which are antagonistic to those of acetylcholine and vasoactive intestinal peptide, the present results raise the possibility that these three substances may have complementary effects on other target tissues

Immunoneutralization of endogenous glucagon-like peptide-2 reduces adaptive intestinal growth in diabetic rats

DEFF Research Database (Denmark)

Hartmann, Bolette; Thulesen, Jesper; Hare, Kristine Juul

2002-01-01

in the proximal part of the small intestine (10.84+/-0.44 mm(2)). Antibody treatment had no effect on body weight, blood glucose concentrations and food intake. Thus, blocking of endogenous GLP-2 in a model of adaptive intestinal growth reduces the growth response, providing strong evidence for a physiological......Supraphysiological doses of glucagon-like peptide-2 (GLP-2) have been shown to induce intestinal growth by increasing villus height and crypt depth and by decreasing apoptosis, but a physiological effect of GLP-2 has not yet been demonstrated. Earlier, we found elevated levels of endogenous GLP-2...... in untreated streptozotocin diabetic rats associated with marked intestinal growth. In the present study, we investigated the role of endogenous GLP-2 for this adaptive response. We included four groups of six rats: (1) diabetic rats treated with saline, (2) diabetic rats treated with non-specific antibodies...

Enteral peptide formulas inhibit radiation induced enteritis and apoptosis in intestinal epithelial cells and suppress the expression and function of Alzheimer's and cell division control gene products

International Nuclear Information System (INIS)

Cope, F.O.; Issinger, O.G.; McArdle, A.H.; Shapiro, J.; Tomei, L.D.

1991-01-01

Studies have shown that patients receiving enteral peptide formulas prior to irradiation have a significantly reduced incidence of enteritis and express a profound increase in intestinal cellularity. Two conceptual approaches were taken to describe this response. First was the evaluation in changes in programmed intestinal cell death and secondly the evaluation of a gene product controlling cell division cycling. This study provided a relationship between the ratio of cell death to cell formulations. The results indicate that in the canine and murine models, irradiation induces expression of the Alzheimer's gene in intestinal crypt cells, while the incidence of apoptosis in apical cells is significantly increased. The use of peptide enteral formulations suppresses the expression of the Alzheimer's gene in crypt cells, while apoptosis is eliminated in the apical cells of the intestine. Concomitantly, enteral peptide formulations suppress the function of the CK-II gene product in the basal and baso-lateral cells of the intestine. These data indicate that although the mitotic index is significantly reduced in enterocytes, this phenomenon alone is not sufficient to account for the peptide-induced radio-resistance of the intestine. The data also indicate a significant reduction of normal apoptosis in the upper lateral and apical cells of the intestinal villi. Thus, the ratio of cell death to cell replacement is significantly decreased resulting in an increase in villus height and hypertrophy of the apical villus cells. Thus, peptide solutions should be considered as an adjunct treatment both in radio- and chemotherapy

Comparative cation dependency of sugar transport by crustacean hepatopancreas and intestine

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Ada Duka

2014-06-01

Full Text Available Glucose is transported in crustacean hepatopancreas and intestine by Na+-dependent co-transport, while Na+-dependent D-fructose influx has only been described for the hepatopancreas. It is still unclear if the two sugars are independently transported by two distinct cation-dependent co-transporter carrier systems. In this study, lobster (Homarus americanus hepatopancreas brush border membrane vesicles (BBMV were used to characterize, in detail, the cation-dependency of both D-[3H]-glucose and D-[3H]-fructose influxes, while in vitro perfused intestines were employed to determine the nature of cation-dependent sugar transport across this organ. Over the sodium concentration range of 0–100 mM, both [3H]-glucose and [3H]-fructose influxes (0.1 mM; 1 min uptakes by hepatopancreatic BBMV were hyperbolic functions of [Na+]. [3H]-glucose and [3H]-fructose influxes by hepatopancreatic BBMV over a potassium concentration range of 15–100 mM were hyperbolic functions of [K+]. Both sugars displayed significant (p<0.01 Na+/K+-dependent and cation-independent uptake processes. Transepithelial 25 µM [3H]-glucose and [3H]-fructose fluxes across lobster intestine over luminal sodium and potassium concentration ranges of 0–50 mM and 5–100 mM, respectively, were hyperbolic functions of luminal [Na+] and [K+]. As with hepatopancreatic sugar transport, transepithelial intestinal sugar transport exhibited both significant (p<0.01 Na+/K+-dependent and cation-independent processes. Results suggest that both D-glucose and D-fructose are transported by a single SGLT-type carrier in each organ with sodium being the “preferred”, high affinity, cation for both sugars in the hepatopancreas, and potassium being the “preferred”, high affinity, cation for both sugars in the intestine.

Osmoregulation and epithelial water transport: lessons from the intestine of marine teleost fish.

Science.gov (United States)

Whittamore, Jonathan M

2012-01-01

For teleost fish living in seawater, drinking the surrounding medium is necessary to avoid dehydration. This is a key component of their osmoregulatory strategy presenting the challenge of excreting excess salts while achieving a net retention of water. The intestine has an established role in osmoregulation, and its ability to effectively absorb fluid is crucial to compensating for water losses to the hyperosmotic environment. Despite this, the potential for the teleost intestine to serve as a comparative model for detailed, integrative experimental studies on epithelial water transport has so far gone largely untapped. The following review aims to present an assessment of the teleost intestine as a fluid-transporting epithelium. Beginning with a brief overview of marine teleost osmoregulation, emphasis shifts to the processing of ingested seawater by the gastrointestinal tract and the characteristics of intestinal ion and fluid transport. Particular attention is given to acid-base transfers by the intestine, specifically bicarbonate secretion, which creates the distinctly alkaline gut fluids responsible for the formation of solid calcium carbonate precipitates. The respective contributions of these unique features to intestinal fluid absorption, alongside other recognised ion transport processes, are then subsequently considered within the wider context of the classic physiological problem of epithelial water transport.

Apical-to-basolateral transepithelial transport of cow's milk caseins by intestinal Caco-2 cell monolayers: MS-based quantitation of cellularly degraded α- and β-casein fragments.

Science.gov (United States)

Sakurai, Nao; Nishio, Shunsuke; Akiyama, Yuka; Miyata, Shinji; Oshima, Kenzi; Nadano, Daita; Matsuda, Tsukasa

2018-02-27

Casein is the major milk protein to nourish infants but, in certain population, it causes cow's milk allergy, indicating the uptake of antigenic casein and their peptides through the intestinal epithelium. Using human intestinal Caco-2 cell monolayers, the apical-to-basal transepithelial transport of casein was investigated. Confocal microscopy using component-specific antibodies showed that αs1-casein antigens became detectable as punctate signals at the apical-side cytoplasm and reached to the cytoplasm at a tight-junction level within a few hours. Such intracellular casein signals were more remarkable than those of the other antigens, β-lactoglobulin and ovalbumin, colocalized in part with an early endosome marker protein, EEA1, and decreased in the presence of cytochalasin D or sodium azide and also at lowered temperature at 4 °C. LC-MS analysis of the protein fraction in the basal-side medium identified the αs1-casein fragment including the N-terminal region and the αs2-casein fragment containing the central part of polypeptide at 100∼1000 fmol per well levels. Moreover, β-casein C-terminal overlapping peptides were identified in the peptide fraction below 10 kDa of the basal medium. These results suggest that caseins are partially degraded by cellular proteases and/or peptidases and immunologically active casein fragments are transported to basal side of the cell monolayers.

In vitro evaluation of N-methyl amide tripeptidomimetics as substrates for the human intestinal di-/tri-peptide transporter hPEPT1

DEFF Research Database (Denmark)

Andersen, Rikke; Nielsen, Carsten Uhd; Begtrup, Mikael

2006-01-01

application of N-methyl amide bioisosteres as peptide bond replacements in tripeptides in order to decrease degradation by peptidases and yet retain affinity for and transport via hPEPT1. Seven structurally diverse N-methyl amide tripeptidomimetics were selected based on a principal component analysis...... of structural properties of 6859 N-methyl amide tripeptidomimetics. In vitro extracellular degradation of the selected tripeptidomimetics as well as affinity for and transepithelial transport via hPEPT1 were investigated in Caco-2 cells. Decreased apparent degradation was observed for all tripeptidomimetics...... to be substrates for hPEPT1 than tripeptidomimetics with charged side chains. The results of the present study indicate that the N-methyl amide peptide bond replacement approach for increasing bioavailability of tripeptidomimetic drug candidates is not generally applicable to all tripeptides. Nevertheless...

Select cognitive deficits in Vasoactive Intestinal Peptide deficient mice

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Hagopian Arkady

2008-07-01

Full Text Available Abstract Background The neuropeptide vasoactive intestinal peptide (VIP is widely distributed in the adult central nervous system where this peptide functions to regulate synaptic transmission and neural excitability. The expression of VIP and its receptors in brain regions implicated in learning and memory functions, including the hippocampus, cortex, and amygdala, raise the possibility that this peptide may function to modulate learned behaviors. Among other actions, the loss of VIP has a profound effect on circadian timing and may specifically influence the temporal regulation of learning and memory functions. Results In the present study, we utilized transgenic VIP-deficient mice and the contextual fear conditioning paradigm to explore the impact of the loss of this peptide on a learned behavior. We found that VIP-deficient mice exhibited normal shock-evoked freezing behavior and increases in corticosterone. Similarly, these mutant mice exhibited no deficits in the acquisition or recall of the fear-conditioned behavior when tested 24-hours after training. The VIP-deficient mice exhibited a significant reduction in recall when tested 48-hours or longer after training. Surprisingly, we found that the VIP-deficient mice continued to express circadian rhythms in the recall of the training even in those individual mice whose wheel running wheel activity was arrhythmic. One mechanistic explanation is suggested by the finding that daily rhythms in the expression of the clock gene Period2 continue in the hippocampus of VIP-deficient mice. Conclusion Together these data suggest that the neuropeptide VIP regulates the recall of at least one learned behavior but does not impact the circadian regulation of this behavior.

Peptides actively transported across the tympanic membrane: Functional and structural properties.

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Arwa Kurabi

Full Text Available Otitis media (OM is the most common infectious disease of children under six, causing more antibiotic prescriptions and surgical procedures than any other pediatric condition. By screening a bacteriophage (phage library genetically engineered to express random peptides on their surfaces, we discovered unique peptides that actively transport phage particles across the intact tympanic membrane (TM and into the middle ear (ME. Herein our goals were to characterize the physiochemical peptide features that may underlie trans-TM phage transport; assess morphological and functional effects of phage peptides on the ME and inner ear (IE; and determine whether peptide-bearing phage transmigrate from the ME into the IE. Incubation of five peptide-bearing phage on the TM for over 4hrs resulted in demonstrably superior transport of one peptide, in level and in exponential increase over time. This suggests a preferred peptide motif for TM active transport. Functional and structural comparisons revealed unique features of this peptide: These include a central lysine residue, isoelectric point of 0.0 at physiological pH and a hydrophobic C-terminus. When the optimal peptide was applied to the TM independent of phage, similar transport was observed, indicating that integration into phage is not required. When 109 particles of the four different trans-TM phage were applied directly into the ME, no morphological effects were detected in the ME or IE when compared to saline or wild-type (WT phage controls. Comparable, reversible hearing loss was observed for saline controls, WT phage and trans-TM peptide phage, suggesting a mild conductive hearing loss due to ME fluid. Perilymph titers after ME incubation established that few copies of trans-TM peptide phage crossed into the IE. The results suggest that, within the parameters tested, trans-TM peptides are safe and could be used as potential agents for noninvasive delivery of drugs, particles and gene therapy

Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) in the circulation after sumatriptan

DEFF Research Database (Denmark)

Hansen, Jakob Møller; Fahrenkrug, Jan; Petersen, Jesper Troensegaard

2013-01-01

The origin of migraine pain is still elusive, but increasingly researchers focus on the neuropeptides in the perivascular space of cranial vessels as important mediators of nociceptive input during migraine attacks. The parasympathetic neurotransmitters, pituitary adenylate cyclase activating...... peptide-38 (PACAP38) and vasoactive intestinal peptide (VIP) may be released from parasympathetic fibres and activate sensory nerve fibres during migraine attacks. Triptans are effective and well tolerated in acute migraine management but the exact mechanism of action is still debated. Triptans might...

Orally active-targeted drug delivery systems for proteins and peptides.

Science.gov (United States)

Li, Xiuying; Yu, Miaorong; Fan, Weiwei; Gan, Yong; Hovgaard, Lars; Yang, Mingshi

2014-09-01

In the past decade, extensive efforts have been devoted to designing 'active targeted' drug delivery systems (ATDDS) to improve oral absorption of proteins and peptides. Such ATDDS enhance cellular internalization and permeability of proteins and peptides via molecular recognition processes such as ligand-receptor or antigen-antibody interaction, and thus enhance drug absorption. This review focuses on recent advances with orally ATDDS, including ligand-protein conjugates, recombinant ligand-protein fusion proteins and ligand-modified carriers. In addition to traditional intestinal active transport systems of substrates and their corresponding receptors, transporters and carriers, new targets such as intercellular adhesion molecule-1 and β-integrin are also discussed. ATDDS can improve oral absorption of proteins and peptides. However, currently, no clinical studies on ATDDS for proteins and peptides are underway, perhaps due to the complexity and limited knowledge of transport mechanisms. Therefore, more research is warranted to optimize ATDDS efficiency.

Intestinal permeability and glucagon-like peptide-2 in children with autism

DEFF Research Database (Denmark)

Robertson, Marli A; Sigalet, David L; Holst, Jens Juul

2008-01-01

We measured small intestinal permeability using a lactulose:mannitol sugar permeability test in a group of children with autism, with current or previous gastrointestinal complaints. Secondly, we examined whether children with autism had an abnormal glucagon-like peptide-2 (GLP-2) response...... to feeding. Results were compared with sibling controls and children without developmental disabilities. We enrolled 14 children with autism, 7 developmentally normal siblings of these children and 8 healthy, developmentally normal, unrelated children. Our study did not detect differences in these measures...... of gastrointestinal function in a group of children with autism....

Exenatide, a Glucagon-like Peptide-1 Receptor Agonist, Acutely Inhibits Intestinal Lipoprotein Production in Healthy Humans

NARCIS (Netherlands)

Xiao, Changting; Bandsma, Robert H. J.; Dash, Satya; Szeto, Linda; Lewis, Gary F.

Objective-Incretin-based therapies for the treatment of type 2 diabetes mellitus improve plasma lipid profiles and postprandial lipemia, but their exact mechanism of action remains unclear. Here, we examined the acute effect of the glucagon-like peptide-1 receptor agonist, exenatide, on intestinal

A safety and pharmacokinetic dosing study of glucagon-like peptide 2 in infants with intestinal failure

DEFF Research Database (Denmark)

Sigalet, David L; Brindle, Mary E; Boctor, Dana

2017-01-01

BACKGROUND & AIMS: Glucagon-like peptide 2 (GLP-2) analogues are approved for adults with intestinal failure (IF), but no studies have included infants. This study examined the pharmacokinetics (PK), safety, and nutritional effects of GLP-2 in infants with IF. METHODS: With parental consent (Health...

Intestinal transporters for endogenic and pharmaceutical organic anions

DEFF Research Database (Denmark)

Grandvuinet, Anne Sophie; Vestergaard, Henrik Tang; Rapin, Nicolas

2012-01-01

This review provides an overview of intestinal human transporters for organic anions and stresses the need for standardization of the various in-vitro methods presently employed in drug-drug interaction (DDI) investigations....

Cysteine-rich intestinal protein binds zinc during transmucosal zinc transport

International Nuclear Information System (INIS)

Hempe, J.M.; Cousins, R.J.

1991-01-01

The mechanism of zinc absorption has not been delineated, but kinetic studies show that both passive and carrier-mediated processes are involved. The authors have identified a low molecular mass zinc-binding protein in the soluble fraction of rat intestinal mucosa that could function as an intracellular zinc carrier. The protein was not detected in liver or pancreas, suggesting a role specific to the intestine. The protein binds zinc during transmucosal zinc transport and shows signs of saturation at higher luminal zinc concentrations, characteristics consistent with a role in carrier-mediated zinc absorption. Microsequence analysis of the protein purified by gel-filtration HPCL and SDS/PAGE showed complete identity within the first 41 N-terminal amino acids with the deduced protein sequence of cysteine-rich intestinal protein. These investigators showed that the gene for this protein is developmentally regulated in neonates during the suckling period, conserved in many vertebrate species, and predominantly expressed in the small intestine. Cysteine-rich intestinal protein contains a recently identified conserved sequence of histidine and cysteine residues, the LIM motif, which our results suggest confers metal-binding properties that are important for zinc transport and/or functions of this micronutrient

Transporters for the Intestinal Absorption of Cholesterol, Vitamin E, and Vitamin K.

Science.gov (United States)

Yamanashi, Yoshihide; Takada, Tappei; Kurauchi, Ryoya; Tanaka, Yusuke; Komine, Toko; Suzuki, Hiroshi

2017-04-03

Humans cannot synthesize fat-soluble vitamins such as vitamin E and vitamin K. For this reason, they must be obtained from the diet via intestinal absorption. As the deficiency or excess of these vitamins has been reported to cause several types of diseases and disorders in humans, the intestinal absorption of these nutrients must be properly regulated to ensure good health. However, the mechanism of their intestinal absorption remains poorly understood. Recent studies on cholesterol using genome-edited mice, genome-wide association approaches, gene mutation analyses, and the development of cholesterol absorption inhibitors have revealed that several membrane proteins play crucial roles in the intestinal absorption of cholesterol. Surprisingly, detailed analyses of these cholesterol transporters have revealed that they can also transport vitamin E and vitamin K, providing clues to uncover the molecular mechanisms underlying the intestinal absorption of these fat-soluble vitamins. In this review, we focus on the membrane proteins (Niemann-Pick C1 like 1, scavenger receptor class B type I, cluster of differentiation 36, and ATP-binding cassette transporter A1) that are (potentially) involved in the intestinal absorption of cholesterol, vitamin E, and vitamin K and discuss their physiological and pharmacological importance. We also discuss the related uncertainties that need to be explored in future studies.

Role of the Intestinal Bile Acid Transporters in Bile Acid and Drug Disposition

Science.gov (United States)

Dawson, Paul A.

2011-01-01

Membrane transporters expressed by the hepatocyte and enterocyte play critical roles in maintaining the enterohepatic circulation of bile acids, an effective recycling and conservation mechanism that largely restricts these potentially cytotoxic detergents to the intestinal and hepatobiliary compartments. In doing so, the hepatic and enterocyte transport systems ensure a continuous supply of bile acids to be used repeatedly during the digestion of multiple meals throughout the day. Absorption of bile acids from the intestinal lumen and export into the portal circulation is mediated by a series of transporters expressed on the enterocyte apical and basolateral membranes. The ileal apical sodium-dependent bile acid cotransporter (abbreviated ASBT; gene symbol, SLC10A2) is responsible for the initial uptake of bile acids across the enterocyte brush border membrane. The bile acids are then efficiently shuttled across the cell and exported across the basolateral membrane by the heteromeric Organic Solute Transporter, OSTα-OSTβ. This chapter briefly reviews the tissue expression, physiology, genetics, pathophysiology, and transport properties of the ASBT and OSTα-OSTα. In addition, the chapter discusses the relationship between the intestinal bile acid transporters and drug metabolism, including development of ASBT inhibitors as novel hypocholesterolemic or hepatoprotective agents, prodrug targeting of the ASBT to increase oral bioavailability, and involvement of the intestinal bile acid transporters in drug absorption and drug-drug interactions. PMID:21103970

Single liposome analysis of peptide translocation by the ABC transporter TAPL.

Science.gov (United States)

Zollmann, Tina; Moiset, Gemma; Tumulka, Franz; Tampé, Robert; Poolman, Bert; Abele, Rupert

2015-02-17

ATP-binding cassette (ABC) transporters use ATP to drive solute transport across biological membranes. Members of this superfamily have crucial roles in cell physiology, and some of the transporters are linked to severe diseases. However, understanding of the transport mechanism, especially of human ABC exporters, is scarce. We reconstituted the human lysosomal polypeptide ABC transporter TAPL, expressed in Pichia pastoris, into lipid vesicles (liposomes) and performed explicit transport measurements. We analyzed solute transport at the single liposome level by monitoring the coincident fluorescence of solutes and proteoliposomes in the focal volume of a confocal microscope. We determined a turnover number of eight peptides per minute, which is two orders of magnitude higher than previously estimated from macroscopic measurements. Moreover, we show that TAPL translocates peptides against a large concentration gradient. Maximal filling is not limited by an electrochemical gradient but by trans-inhibition. Countertransport and reversibility studies demonstrate that peptide translocation is a strictly unidirectional process. Altogether, these data are included in a refined model of solute transport by ABC exporters.

Intestinal glutathione: determinant of mucosal peroxide transport, metabolism, and oxidative susceptibility

International Nuclear Information System (INIS)

Aw, Tak Yee

2005-01-01

The intestine is a primary site of nutrient absorption and a critical defense barrier against dietary-derived mutagens, carcinogens, and oxidants. Accumulation of oxidants like peroxidized lipids in the gut lumen can contribute to impairment of mucosal metabolic pathways, enterocyte dysfunction independent of cell injury, and development of gut pathologies, such as inflammation and cancer. Despite this recognition, we know little of the pathways of intestinal transport, metabolism, and luminal disposition of dietary peroxides in vivo or of the underlying mechanisms of lipid peroxide-induced genesis of intestinal disease processes. This chapter summarizes our current understanding of the determinants of intestinal absorption and metabolism of peroxidized lipids. I will review experimental evidence from our laboratory and others (Table 1) supporting the pivotal role that glutathione (GSH) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) play in mucosal transport and metabolism of lipid hydroperoxides and how reductant availability can be compromised under chronic stress such as hypoxia, and the influence of GSH on oxidative susceptibility, and redox contribution to genesis of gut disorders. The discussion is pertinent to understanding dietary lipid peroxides and GSH redox balance in intestinal physiology and pathophysiology and the significance of luminal GSH in preserving the integrity of the intestinal epithelium

Glucagon-like peptide-2 protects impaired intestinal mucosal barriers in obstructive jaundice rats.

Science.gov (United States)

Chen, Jun; Dong, Jia-Tian; Li, Xiao-Jing; Gu, Ye; Cheng, Zhi-Jian; Cai, Yuan-Kun

2015-01-14

To observe the protective effect of glucagon-like peptide-2 (GLP-2) on the intestinal barrier of rats with obstructive jaundice and determine the possible mechanisms of action involved in the protective effect. Thirty-six Sprague-Dawley rats were randomly divided into a sham operation group, an obstructive jaundice group, and a GLP-2 group; each group consisted of 12 rats. The GLP-2 group was treated with GLP-2 after the day of surgery, whereas the other two groups were treated with the same concentration of normal saline. Alanine aminotransferase (ALT), total bilirubin, and endotoxin levels were recorded at 1, 3, 7, 10 and 14 d. Furthermore, on the 14(th) day, body weight, the wet weight of the small intestine, pathological changes of the small intestine and the immunoglobulin A (IgA) expressed by plasma cells located in the small intestinal lamina propria were recorded for each group. In the rat model, jaundice was obvious, and the rats' activity decreased 4-6 d post bile duct ligation. Compared with the sham operation group, the obstructive jaundice group displayed increased yellow staining of abdominal visceral serosa, decreased small intestine wet weight, thinning of the intestinal muscle layer and villi, villous atrophy, uneven height, fusion, partial villous epithelial cell shedding, substantial inflammatory cell infiltration and significantly reduced IgA expression. However, no significant gross changes were noted between the GLP-2 and sham groups. With time, the levels of ALT, endotoxin and bilirubin in the GLP-2 group were significantly increased compared with the sham group (P jaundice group than in the GLP-2 group (P jaundice rats, which might be attributed to increased intestinal IgA and reduced bilirubin and endotoxin.

Salmonella infection inhibits intestinal biotin transport: cellular and molecular mechanisms.

Science.gov (United States)

Ghosal, Abhisek; Jellbauer, Stefan; Kapadia, Rubina; Raffatellu, Manuela; Said, Hamid M

2015-07-15

Infection with the nontyphoidal Salmonella is a common cause of food-borne disease that leads to acute gastroenteritis/diarrhea. Severe/prolonged cases of Salmonella infection could also impact host nutritional status, but little is known about its effect on intestinal absorption of vitamins, including biotin. We examined the effect of Salmonella enterica serovar Typhimurium (S. typhimurium) infection on intestinal biotin uptake using in vivo (streptomycin-pretreated mice) and in vitro [mouse (YAMC) and human (NCM460) colonic epithelial cells, and human intestinal epithelial Caco-2 cells] models. The results showed that infecting mice with wild-type S. typhimurium, but not with its nonpathogenic isogenic invA spiB mutant, leads to a significant inhibition in jejunal/colonic biotin uptake and in level of expression of the biotin transporter, sodium-dependent multivitamin transporter. In contrast, infecting YAMC, NCM460, and Caco-2 cells with S. typhimurium did not affect biotin uptake. These findings suggest that the effect of S. typhimurium infection is indirect and is likely mediated by proinflammatory cytokines, the levels of which were markedly induced in the intestine of S. typhimurium-infected mice. Consistent with this hypothesis, exposure of NCM460 cells to the proinflammatory cytokines TNF-α and IFN-γ led to a significant inhibition of biotin uptake, sodium-dependent multivitamin transporter expression, and activity of the SLC5A6 promoter. The latter effects appear to be mediated, at least in part, via the NF-κB signaling pathway. These results demonstrate that S. typhimurium infection inhibits intestinal biotin uptake, and that the inhibition is mediated via the action of proinflammatory cytokines.

Mechanisms of calcium transport in small intestine. Final report

International Nuclear Information System (INIS)

DeLuca, H.F.

1982-01-01

The vitamin D hormone, 1,25-dihydroxyvitamin D 3 , was demonstrated to be the prime hormonal agent regulating intestinal absorption of divalent cations. Production of the vitamin D hormone is, in turn, regulated by parathyroid hormone, low dietary calcium, low plasma phosphorus, and is suppressed by 1,25-dihydroxyvitamin D 3 , by high plasma phosphorus, high plasma calcium, and the absence of parathyroid hormone. A variety of analogs of the vitamin D hormone were prepared. In addition, the preparation of radiolabeled vitamin D hormone was accomplished using chemical synthesis, and this highly radioactive substance was found to localize in the nuclei of the intestinal villus cells that promote intestinal absorption of calcium. A receptor for the vitamin D hormone was also located, and the general mechanism of response to the vitamin D hormone included the binding to a receptor molecule, transfer to the nucleus, transcription of specific genes followed by translation to transport proteins. Methods were developed for the discovery of the appropriate gene products that play a role in calcium transport

Functionalized PLA-PEG nanoparticles targeting intestinal transporter PepT1 for oral delivery of acyclovir.

Science.gov (United States)

Gourdon, Betty; Chemin, Caroline; Moreau, Amélie; Arnauld, Thomas; Baumy, Philippe; Cisternino, Salvatore; Péan, Jean-Manuel; Declèves, Xavier

2017-08-30

Targeting intestinal di- and tri-peptide transporter PepT1 with prodrugs is a successful strategy to improve oral drug bioavailability, as demonstrated with valacyclovir, a prodrug of acyclovir. The aim of this new drug delivery strategy is to over-concentrate a poorly absorbed drug on the intestinal membrane surface by targeting PepT1 with functionalized polymer nanoparticles. In the present study, poly(lactic acid)-poly(ethylene glycol)-ligand (PLA-PEG-ligand) nanoparticles were obtained by nanoprecipitation. A factorial experimental design allowed us to identify size-influent parameters and to obtain optimized ≈30nm nanoparticles. Valine, Glycylsarcosine, Valine-Glycine, and Tyrosine-Valine were chemically linked to PLA-PEG. In Caco-2 cell monolayer model, competition between functionalized nanoparticles and [ 3 H]Glycylsarcosine, a strong substrate of PepT1, reduced [ 3 H]Glycylsarcosine transport from 22 to 46%. Acyclovir was encapsulated with a drug load of ≈10% in valine-functionalized nanoparticles, resulting in a 2.7-fold increase in permeability as compared to the free drug. An in vivo pharmacokinetic study in mice compared oral absorption of acyclovir after administration of 25mg/kg of valacyclovir, free or encapsulated acyclovir in functionalized nanoparticles. Acyclovir encapsulation did not statistically modify AUC or C max , but increased t 1/2 and MRT 1.3-fold as compared to free acyclovir. This new strategy is promising for poorly absorbed drugs by oral administration. Copyright © 2017 Elsevier B.V. All rights reserved.

Endocrine regulation of ion transport in the avian lower intestine

DEFF Research Database (Denmark)

Laverty, Gary; Elbrønd, Vibeke Sødring; Árnason, Sighvatur S.

2006-01-01

The lower intestine (colon and coprodeum) of the domestic fowl maintains a very active, transporting epithelium, with a microvillus brush border, columnar epithelial cells, and a variety of transport systems. The colon of normal or high salt-acclimated hens expresses sodium-linked glucose and amino...

Perinatal upregulation of intestinal transport of carnitine (C) in newborn pigs

International Nuclear Information System (INIS)

Li, B.U.K.; Murray, R.D.; Heitlinger, L.A.; McClung, H.J.; Hughes, A.M.; O'Dorisio, T.M.; Sloan, H.R.

1990-01-01

Since C facilitates the perinatal transition from carbohydrate to lipid-derived energy, the authors examined the contribution of intestinal transport of dietary C to this process by determining [C]'s in sow's milk, pig jejunum and liver, and C flux across the jejunum (J m-s ) as a function of postnatal age. The authors measured portal venous glucagon [G] and insulin [l] as potential regulatory signals and attempted to alter intestinal transport of C by infusing G. Pigs at days 1-7 (NB-newborn), 14-16 (SU-suckling) and 33-35 (WN-weanling) were studied. [C]'s in sow milk, piglet jejunum, and liver were determined. Fluxes were measured in an Ussing chamber and in an in situ recirculating jejunal perfusion. The effect of an IV infusion of G on [ 3 H]C absorption was evaluated in a single animal; an adjacent jejunal segment received saline. Sow's milk and liver [C]'s, and jejunal C transport were highest following birth and declined towards weaning. Plasma [G] and the G:I ratio demonstrated a parallel temporal pattern. The G-stimulated jejunal segment removed 53% of the C and the non-stimulated control segment, 8%. It was concluded that during the perinatal metabolic transition, enhanced intestinal nutrient assimilation promotes the transfer of dietary C to the liver where it could facilitate fatty acid oxidation. This pattern of upregulated intestinal transport immediately after birth may be mediated by pancreatic G and I secretion

Transepithelial Transport of PAMAM Dendrimers Across Isolated Human Intestinal Tissue.

Science.gov (United States)

Hubbard, Dallin; Enda, Michael; Bond, Tanner; Moghaddam, Seyyed Pouya Hadipour; Conarton, Josh; Scaife, Courtney; Volckmann, Eric; Ghandehari, Hamidreza

2015-11-02

Poly(amido amine) (PAMAM) dendrimers have shown transepithelial transport across intestinal epithelial barrier in rats and across Caco-2 cell monolayers. Caco-2 models innately lack mucous barriers, and rat isolated intestinal tissue has been shown to overestimate human permeability. This study is the first report of transport of PAMAM dendrimers across isolated human intestinal epithelium. It was observed that FITC labeled G4-NH2 and G3.5-COOH PAMAM dendrimers at 1 mM concentration do not have a statistically higher permeability compared to free FITC controls in isolated human jejunum and colonic tissues. Mannitol permeability was increased at 10 mM concentrations of G3.5-COOH and G4-NH2 dendrimers. Significant histological changes in human colonic and jejunal tissues were observed at G3.5-COOH and G4-NH2 concentrations of 10 mM implying that dose limiting toxicity may occur at similar concentrations in vivo. The permeability through human isolated intestinal tissue in this study was compared to previous rat and Caco-2 permeability data. This study implicates that PAMAM dendrimer oral drug delivery may be feasible, but it may be limited to highly potent drugs.

The Down regulated in Adenoma (dra) gene encodes an intestine-specific membrane sulfate transport protein.

Science.gov (United States)

Silberg, D G; Wang, W; Moseley, R H; Traber, P G

1995-05-19

A gene has been described, Down Regulated in Adenoma (dra), which is expressed in normal colon but is absent in the majority of colon adenomas and adenocarcinomas. However, the function of this protein is unknown. Because of sequence similarity to a recently cloned membrane sulfate transporter in rat liver, the transport function of Dra was examined. We established that dra encodes for a Na(+)-independent transporter for both sulfate and oxalate using microinjected Xenopus oocytes as an assay system. Sulfate transport was sensitive to the anion exchange inhibitor DIDS (4,4'-diisothiocyano-2,2' disulfonic acid stilbene). Using an RNase protection assay, we found that dra mRNA expression is limited to the small intestine and colon in mouse, therefore identifying Dra as an intestine-specific sulfate transporter. dra also had a unique pattern of expression during intestinal development. Northern blot analysis revealed a low level of expression in colon at birth with a marked increase in the first 2 postnatal weeks. In contrast, there was a lower, constant level of expression in small intestine in the postnatal period. Caco-2 cells, a colon carcinoma cell line that differentiates over time in culture, demonstrated a marked induction of dra mRNA as cells progressed from the preconfluent (undifferentiated) to the postconfluent (differentiated) state. These results show that Dra is an intestine-specific Na(+)-independent sulfate transporter that has differential expression during colonic development. This functional characterization provides the foundation for investigation of the role of Dra in intestinal sulfate transport and in the malignant phenotype.

Radioiodination of vasoactive intestinal peptide (VIP)

International Nuclear Information System (INIS)

Wang, Y.; Wang, L.; Yin, D.

2002-01-01

In recent years, increasing biochemical and radiochemical research has been performed to develop radiolabelled peptides as specific ligands for tumour associated receptors. VIP, a 28-amino acid peptide containing two tyrosines and three lysines, has demonstrated that various tumour cells express significantly higher amounts of VIP-receptors and could be applied to the clinic diagnosis. For these purposes, radiohalogenation of VIP by direct and indirect method was studied. Direct labelling works well for radioiodine but is limited to dehalogenation of labelling products in vivo. Conjugate labelling methods including Boltonhunter and wood reagents were developed but introduction of such a molecule to peptides may lead to the decrease of biological activity in vivo. In order to resolve these problems, N-Succinimidyl-3-(tri-nbutylstannyl) benzoate (ATE) was elected for the radioiodination of VIP and already employed to radioiodination of IgG successfully. The in vitro stability and biological activity would be compared in these two methods. Vasoactive intestinal peptide (VIP) and human immunoglobulin (IgG) were radioiodinated by direct and indirect methods. Iodogen was employed in direct method and N-Succinimidyl-3-(tri-n-butylstannyl) benzoate (ATE) was applied as a prosthetic group in the conjugation labelling. The subject of our study was optimizing the radiohalogenation of IgG and VIP followed by separation and analysis of reaction products. The advantages and disadvantages were illustrated by comparing the in vitro stability and biological activity in these two methods. Na 123 I was prepared by nuclear reaction of 124 Te(p, 2n) 123 I using cyclone-30. More than 95% of radiochemical purity, more than 95% of radionuclide purity and about 100 mCi/mL of radioactivity concentration were obtained. ATE was supplied by Dr. Pozzi and radioiodinated with iodogen and 96% of labelling efficiency was obtained. The stability of radioactive S 125 IB kept well in dark at 4

Effect of dietary lead on intestinal nutrient transporters mRNA expression in broiler chickens.

Science.gov (United States)

Ebrahimi, Roohollah; Faseleh Jahromi, Mohammad; Liang, Juan Boo; Soleimani Farjam, Abdoreza; Shokryazdan, Parisa; Idrus, Zulkifli

2015-01-01

Lead- (Pb-) induced oxidative stress is known to suppress growth performance and feed efficiency in broiler chickens. In an attempt to describe the specific underlying mechanisms of such phenomenon we carried out the current study. Ninety-six one-day-old broiler chicks were randomly assigned to 2 dietary treatment groups of 6 pen replicates, namely, (i) basal diet containing no lead supplement (control) and (ii) basal diet containing 200 mg lead acetate/kg of diet. Following 3 weeks of experimental period, jejunum samples were collected to examine the changes in gene expression of several nutrient transporters, antioxidant enzymes, and heat shock protein 70 (Hsp70) using quantitative real-time PCR. The results showed that addition of lead significantly decreased feed intake, body weight gain, and feed efficiency. Moreover, with the exception of GLUT5, the expression of all sugar, peptide, and amino acid transporters was significantly downregulated in the birds under Pb induced oxidative stress. Exposure to Pb also upregulated the antioxidant enzymes gene expression together with the downregulation of glutathione S-transferase and Hsp70. In conclusion, it appears that Pb-induced oxidative stress adversely suppresses feed efficiency and growth performance in chicken and the possible underlying mechanism for such phenomenon is downregulation of major nutrient transporter genes in small intestine.

Human Enteroids as a Model of Upper Small Intestinal Ion Transport Physiology and Pathophysiology

NARCIS (Netherlands)

J. Foulke-Abel (Jennifer); J. In (Julie); Yin, J. (Jianyi); N.C. Zachos (Nicholas C.); O. Kovbasnjuk (Olga); M.K. Estes (Mary K.); H.R. de Jonge (Hugo); M. Donowitz (Mark)

2016-01-01

textabstractBackground & Aims Human intestinal crypt-derived enteroids are a model of intestinal ion transport that require validation by comparison with cell culture and animal models. We used human small intestinal enteroids to study neutral Na+ absorption and stimulated fluid and anion secretion

Effect of pomegranate juice pre-treatment on the transport of carbamazepine across rat intestine

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D Adukondalu

2010-12-01

Full Text Available "n  "nBackground and the purpose of the study: Many drug substances along with a variety of naturally occurring dietary or herbal components interact with the CYP enzyme system.The present study was aimed to investigate the effect of pomegranate juice pre-treatment on the transport of carbamazepine across the rat intestine "nMethods: The transport of carbamazepine across different parts of rat intestine was studied by everted and non-everted sac methods. The control and pomegranate juice (10 ml Kg-1 for 7 days pre-treated rats were sacrificed and isolated the intestine. The sacs of intestine were prepared, treated with carbamazepine solution and then placed in dulbeccos buffer. Samples were collected periodically and the drug content was estimated using HPLC. Results and conclusion: The results show that there was a significant (p<0.05 difference in the transport of carbamazepine from the intestinal sacs of pretreated with pomegranate juice and control. It seems that pomegranatejuice might have induced CYP3A4enzymes and hence drug is extensively metabolized.

Expression of digestive enzymes and nutrient transporters in Eimeria-challenged broilers.

Science.gov (United States)

Su, S; Miska, K B; Fetterer, R H; Jenkins, M C; Wong, E A

2015-03-01

Avian coccidiosis is a disease caused by the intestinal protozoa Eimeria. The site of invasion and lesions in the intestine is species-specific, for example E. acervulina affects the duodenum, E. maxima the jejunum, and E. tenella the ceca. Lesions in the intestinal mucosa cause reduced feed efficiency and body weight gain. The growth reduction may be due to changes in expression of digestive enzymes and nutrient transporters in the intestine. The objective of this study was to compare the expression of digestive enzymes, nutrient transporters and an antimicrobial peptide in broilers challenged with either E. acervulina, E. maxima or E. tenella. The genes examined included digestive enzymes (APN and SI), peptide and amino acid transporters (PepT1, ASCT1, b(0,+)AT/rBAT, B(0)AT, CAT1, CAT2, EAAT3, LAT1, y(+)LAT1 and y(+)LAT2), sugar transporters (GLUT1, GLUT2, GLUT5 and SGLT1), zinc transporter (ZnT1) and an antimicrobial peptide (LEAP2). Duodenum, jejunum, ileum and ceca were collected 7 days post challenge. E. acervulina challenge resulted in downregulation of various nutrient transporters or LEAP2 in the duodenum and ceca, but not the jejunum or ileum. E. maxima challenge produced both downregulation and upregulation of nutrient transporters and LEAP2 in all three segments of the small intestine and ceca. E. tenella challenge resulted in the downregulation and upregulation of nutrient transporters and LEAP2 in the jejunum, ileum and ceca, but not the duodenum. At the respective target tissue, E. acervulina, E. maxima and E. tenella infection caused common downregulation of APN, b(0,+)AT, rBAT, EAAT3, SI, GLUT2, GLUT5, ZnT1 and LEAP2. The downregulation of nutrient transporters would result in a decrease in the efficiency of protein and polysaccharide digestion and uptake, which may partially explain the weight loss. The downregulation of nutrient transporters may also be a cellular response to reduced expression of the host defense protein LEAP2, which would

Stereospecific transport of Tyr-MIF-1 across the blood-brain barrier by peptide transport system-1

Energy Technology Data Exchange (ETDEWEB)

Banks, W.A.; Kastin, A.J.; Michals, E.A.; Barrera, C.M. (Veterans Affairs Medical Center, New Orleans, LA (USA))

1990-10-01

Previous studies have suggested that peptide transport system-1 (PTS-1), the saturable system that transports Tyr-MIF-1, the enkephalins, and related peptides out of the central nervous system (CNS), exhibits stereospecificity. In the present studies, we showed that {sup 125}I-L-Tyr-MIF-1, but not {sup 131}I-D-Tyr-MIF-1, was cleared from the CNS more rapidly than could be accounted for by nonspecific mechanisms. Such clearance was inhibited by a 1.0 nmol dose of L-Tyr-MIF-1, but not by D-Tyr-MIF-1. Neither L- nor D-Tyr-MIF-1 altered the much lower clearance of I-D-Tyr-MIF-1 from the brain. Radioactivity recovered from the vascular space after the injection of {sup 125}I-Tyr-MIF-1 into the lateral ventricle of the brain eluted by HPLC primarily as intact peptide, demonstrating that most of the Tyr-MIF-1 was not degraded during transport. By contrast, the nonsaturable unidirectional influx of Tyr-MIF-1 into the CNS did not distinguish between the isomers. These studies confirm and extend the observations that Tyr-MIF-1 is transported out of the CNS by a saturable, stereospecific transport system as an intact peptide while the influx into the CNS is by a nonsaturable mechanism that does not distinguish between the isomers.

Pharmacologic Effects in vivo in Brain by Vector-Mediated Peptide Drug Delivery

Science.gov (United States)

Bickel, Ulrich; Yoshikawa, Takayoshi; Landaw, Elliot M.; Faull, Kym F.; Pardridge, William M.

1993-04-01

Pharmacologic effects in brain caused by systemic administration of neuropeptides are prevented by poor transport of the peptide through the brain vascular endothelium, which comprises the blood-brain barrier in vivo. In the present study, successful application of a chimeric peptide approach to enhance drug delivery through the blood-brain barrier for the purpose of achieving a central nervous system pharmacologic effect is described. The chimeric peptide was formed by linkage of a potent vasoactive intestinal peptide (VIP) analogue, which had been monobiotinylated, to a drug transport vector. The vector consisted of a covalent conjugate of avidin and the OX26 monoclonal antibody to the transferrin receptor. Owing to the high concentration of transferrin receptors on brain capillary endothelia, OX26 targets brain and undergoes receptor-mediated transcytosis through the blood-brain barrier. Systemic infusion of low doses (12 μg/kg) of the VIP chimeric peptide in rats resulted in an in vivo central nervous system pharmacologic effect: a 65% increase in cerebral blood flow. Biotinylated VIP analogue without the brain transport vector was ineffective.

Intestinal cholesterol transport: Measuring cholesterol absorption and its reverse

NARCIS (Netherlands)

Jakulj, L.

2013-01-01

Intestinal cholesterol transport might serve as an attractive future target for cardiovascular disease reduction, provided that underlying molecular mechanisms are more extensively elucidated, combined with improved techniques to measure changes in cholesterol fluxes and their possible

Zinc Transporter SLC39A7/ZIP7 Promotes Intestinal Epithelial Self-Renewal by Resolving ER Stress

Science.gov (United States)

Ohashi, Wakana; Kimura, Shunsuke; Iwanaga, Toshihiko; Furusawa, Yukihiro; Irié, Tarou; Izumi, Hironori; Watanabe, Takashi; Hara, Takafumi; Ohara, Osamu; Koseki, Haruhiko; Sato, Toshiro; Robine, Sylvie; Mori, Hisashi; Hattori, Yuichi; Mishima, Kenji; Ohno, Hiroshi; Hase, Koji; Fukada, Toshiyuki

2016-01-01

Zinc transporters play a critical role in spatiotemporal regulation of zinc homeostasis. Although disruption of zinc homeostasis has been implicated in disorders such as intestinal inflammation and aberrant epithelial morphology, it is largely unknown which zinc transporters are responsible for the intestinal epithelial homeostasis. Here, we show that Zrt-Irt-like protein (ZIP) transporter ZIP7, which is highly expressed in the intestinal crypt, is essential for intestinal epithelial proliferation. Mice lacking Zip7 in intestinal epithelium triggered endoplasmic reticulum (ER) stress in proliferative progenitor cells, leading to significant cell death of progenitor cells. Zip7 deficiency led to the loss of Olfm4+ intestinal stem cells and the degeneration of post-mitotic Paneth cells, indicating a fundamental requirement for Zip7 in homeostatic intestinal regeneration. Taken together, these findings provide evidence for the importance of ZIP7 in maintenance of intestinal epithelial homeostasis through the regulation of ER function in proliferative progenitor cells and maintenance of intestinal stem cells. Therapeutic targeting of ZIP7 could lead to effective treatment of gastrointestinal disorders. PMID:27736879

Zinc Transporter SLC39A7/ZIP7 Promotes Intestinal Epithelial Self-Renewal by Resolving ER Stress.

Directory of Open Access Journals (Sweden)

Wakana Ohashi

2016-10-01

Full Text Available Zinc transporters play a critical role in spatiotemporal regulation of zinc homeostasis. Although disruption of zinc homeostasis has been implicated in disorders such as intestinal inflammation and aberrant epithelial morphology, it is largely unknown which zinc transporters are responsible for the intestinal epithelial homeostasis. Here, we show that Zrt-Irt-like protein (ZIP transporter ZIP7, which is highly expressed in the intestinal crypt, is essential for intestinal epithelial proliferation. Mice lacking Zip7 in intestinal epithelium triggered endoplasmic reticulum (ER stress in proliferative progenitor cells, leading to significant cell death of progenitor cells. Zip7 deficiency led to the loss of Olfm4+ intestinal stem cells and the degeneration of post-mitotic Paneth cells, indicating a fundamental requirement for Zip7 in homeostatic intestinal regeneration. Taken together, these findings provide evidence for the importance of ZIP7 in maintenance of intestinal epithelial homeostasis through the regulation of ER function in proliferative progenitor cells and maintenance of intestinal stem cells. Therapeutic targeting of ZIP7 could lead to effective treatment of gastrointestinal disorders.

Ghrelin suppresses cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) in the intestine, and attenuates the anorectic effects of CCK, PYY and GLP-1 in goldfish (Carassius auratus).

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Blanco, Ayelén Melisa; Bertucci, Juan Ignacio; Valenciano, Ana Isabel; Delgado, María Jesús; Unniappan, Suraj

2017-07-01

Ghrelin is an important gut-derived hormone with an appetite stimulatory role, while most of the intestinal hormones, including cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 (GLP-1), are appetite-inhibitors. Whether these important peptides with opposing roles on food intake interact to regulate energy balance in fish is currently unknown. The aim of this study was to characterize the putative crosstalk between ghrelin and CCK, PYY and GLP-1 in goldfish (Carassius auratus). We first determined the localization of CCK, PYY and GLP-1 in relation to ghrelin and its main receptor GHS-R1a (growth hormone secretagogue 1a) in the goldfish intestine by immunohistochemistry. Colocalization of ghrelin/GHS-R1a and CCK/PYY/GLP-1 was found primarily in the luminal border of the intestinal mucosa. In an intestinal explant culture, a significant decrease in prepro-cck, prepro-pyy and proglucagon transcript levels was observed after 60min of incubation with ghrelin, which was abolished by preincubation with the GHS-R1a ghrelin receptor antagonist [D-Lys3]-GHRP-6 (except for proglucagon). The protein expression of PYY and GLP-1 was also downregulated by ghrelin. Finally, intraperitoneal co-administration of CCK, PYY or GLP-1 with ghrelin results in no modification of food intake in goldfish. Overall, results of the present study show for the first time in fish that ghrelin exerts repressive effects on enteric anorexigens. It is likely that these interactions mediate the stimulatory effects of ghrelin on feeding and metabolism in fish. Copyright © 2017 Elsevier Inc. All rights reserved.

Intestinal ion transport in rats with spontaneous arterial hypertension.

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Lübcke, R; Barbezat, G O

1988-08-01

1. Ion balance, intestinal ion transport in vivo with luminal Ringer, and direct voltage clamping in vivo with luminal Ringer and sodium-free choline-Ringer were studied in young (40 days old) and adult (120 days old) spontaneously hypertensive rats (SHR) and age-matched normotensive controls (Wistar-Kyoto rats, WKY). 2. Faecal sodium output was significantly higher in SHR compared with WKY in both young (+67%) and adult (+43%) rats. 3. Small-intestinal sodium absorption was equal in young SHR and WKY, but significantly greater net sodium absorption was found in the ileum of adult SHR. In contrast, net sodium absorption was reduced from the colon of both young and adult SHR. 4. In adult SHR, the colonic transepithelial short-circuit current (Isc) and the transepithelial potential difference (PD) were significantly higher, whereas the transepithelial membrane resistance (Rm) was significantly lower than in WKY. There was an identical drop in Isc in both strains when luminal sodium was replaced by choline. These data cannot be explained by increased electrogenic cation (sodium) absorption in the SHR, but would favour chloride secretion. 5. It is suggested that in SHR membrane electrolyte transport abnormalities may also be present in the epithelial cells of the small and large intestine, as have been demonstrated already in blood cells by several investigators. The SHR may become an interesting experimental animal model for the study of generalized ion transport disorders.

The effects of fluorouracil, epirubicin, and cyclophosphamide (FEC60 on the intestinal barrier function and gut peptides in breast cancer patients: an observational study

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Russo Francesco

2013-02-01

Full Text Available Abstract Background Several GI peptides linked to intestinal barrier function could be involved in the modification of intestinal permeability and the onset of diarrhea during adjuvant chemotherapy. The aim of the study was to evaluate the circulating levels of zonulin, glucagon-like peptide-2 (GLP-2, epidermal growth factor (EGF and ghrelin and their relationship with intestinal permeability and chemotherapy induced diarrhea (CTD. Methods Sixty breast cancer patients undergoing an FEC60 regimen were enrolled, 37 patients completed the study. CTD(+ patients were discriminated by appropriate questionnaire and criteria. During chemotherapy, intestinal permeability was assessed by lactulose/mannitol urinary test on day 0 and day 14. Zonulin, GLP-2, EGF and ghrelin circulating levels were evaluated by ELISA tests at five time-points (days 0, 3, 10, 14, and 21. Results During FEC60 administration, the lactulose/mannitol ratio was significantly higher on day 14 than at baseline. Zonulin levels were not affected by chemotherapy, whereas GLP-2 and EGF levels decreased significantly. GLP-2 levels on day 14 were significantly lower than those on day 0 and day 3, while EGF values were significantly lower on day 10 than at the baseline. In contrast, the total concentrations of ghrelin increased significantly at day 3 compared to days 0 and 21, respectively. Ten patients (27% suffered from diarrhea. On day 14 of chemotherapy, a significant increase of the La/Ma ratio occurred in CTD(+ patients compared to CTD(− patients. With regards to circulating gut peptides, the AUCg of GLP-2 and ghrelin were significantly lower and higher in CTD(+ patients than CTD(− ones, respectively. Finally in CTD(+ patients a significant and inverse correlation between GLP-2 and La/Ma ratio was found on day 14. Conclusions Breast cancer patients undergoing FEC60 showed alterations in the intestinal permeability, which was associated with modifications in the levels of GLP-2

The effects of fluorouracil, epirubicin, and cyclophosphamide (FEC60) on the intestinal barrier function and gut peptides in breast cancer patients: an observational study.

Science.gov (United States)

Russo, Francesco; Linsalata, Michele; Clemente, Caterina; D'Attoma, Benedetta; Orlando, Antonella; Campanella, Giovanna; Giotta, Francesco; Riezzo, Giuseppe

2013-02-04

Several GI peptides linked to intestinal barrier function could be involved in the modification of intestinal permeability and the onset of diarrhea during adjuvant chemotherapy. The aim of the study was to evaluate the circulating levels of zonulin, glucagon-like peptide-2 (GLP-2), epidermal growth factor (EGF) and ghrelin and their relationship with intestinal permeability and chemotherapy induced diarrhea (CTD). Sixty breast cancer patients undergoing an FEC60 regimen were enrolled, 37 patients completed the study. CTD(+) patients were discriminated by appropriate questionnaire and criteria. During chemotherapy, intestinal permeability was assessed by lactulose/mannitol urinary test on day 0 and day 14. Zonulin, GLP-2, EGF and ghrelin circulating levels were evaluated by ELISA tests at five time-points (days 0, 3, 10, 14, and 21). During FEC60 administration, the lactulose/mannitol ratio was significantly higher on day 14 than at baseline. Zonulin levels were not affected by chemotherapy, whereas GLP-2 and EGF levels decreased significantly. GLP-2 levels on day 14 were significantly lower than those on day 0 and day 3, while EGF values were significantly lower on day 10 than at the baseline. In contrast, the total concentrations of ghrelin increased significantly at day 3 compared to days 0 and 21, respectively. Ten patients (27%) suffered from diarrhea. On day 14 of chemotherapy, a significant increase of the La/Ma ratio occurred in CTD(+) patients compared to CTD(-) patients. With regards to circulating gut peptides, the AUCg of GLP-2 and ghrelin were significantly lower and higher in CTD(+) patients than CTD(-) ones, respectively. Finally in CTD(+) patients a significant and inverse correlation between GLP-2 and La/Ma ratio was found on day 14. Breast cancer patients undergoing FEC60 showed alterations in the intestinal permeability, which was associated with modifications in the levels of GLP-2, ghrelin and EGF. In CTD(+) patients, a different GI peptide

Intestinal Transport Characteristics and Metabolism of C-Glucosyl Dihydrochalcone, Aspalathin

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Sandra Bowles

2017-03-01

Full Text Available Insight into the mechanisms of intestinal transport and metabolism of aspalathin will provide important information for dose optimisation, in particular for studies using mouse models. Aspalathin transportation across the intestinal barrier (Caco-2 monolayer tested at 1–150 µM had an apparent rate of permeability (Papp typical of poorly absorbed compounds (1.73 × 10−6 cm/s. Major glucose transporters, sodium glucose linked transporter 1 (SGLT1 and glucose transporter 2 (GLUT2, and efflux protein (P-glycoprotein, PgP (1.84 × 10−6 cm/s; efflux ratio: 1.1 were excluded as primary transporters, since the Papp of aspalathin was not affected by the presence of specific inhibitors. The Papp of aspalathin was also not affected by constituents of aspalathin-enriched rooibos extracts, but was affected by high glucose concentration (20.5 mM, which decreased the Papp value to 2.9 × 10−7 cm/s. Aspalathin metabolites (sulphated, glucuronidated and methylated were found in mouse urine, but not in blood, following an oral dose of 50 mg/kg body weight of the pure compound. Sulphates were the predominant metabolites. These findings suggest that aspalathin is absorbed and metabolised in mice to mostly sulphate conjugates detected in urine. Mechanistically, we showed that aspalathin is not actively transported by the glucose transporters, but presumably passes the monolayer paracellularly.

Intestinal Transport Characteristics and Metabolism of C-Glucosyl Dihydrochalcone, Aspalathin.

Science.gov (United States)

Bowles, Sandra; Joubert, Elizabeth; de Beer, Dalene; Louw, Johan; Brunschwig, Christel; Njoroge, Mathew; Lawrence, Nina; Wiesner, Lubbe; Chibale, Kelly; Muller, Christo

2017-03-30

Insight into the mechanisms of intestinal transport and metabolism of aspalathin will provide important information for dose optimisation, in particular for studies using mouse models. Aspalathin transportation across the intestinal barrier (Caco-2 monolayer) tested at 1-150 µM had an apparent rate of permeability (P app ) typical of poorly absorbed compounds (1.73 × 10 -6 cm/s). Major glucose transporters, sodium glucose linked transporter 1 (SGLT1) and glucose transporter 2 (GLUT2), and efflux protein (P-glycoprotein, PgP) (1.84 × 10 -6 cm/s; efflux ratio: 1.1) were excluded as primary transporters, since the P app of aspalathin was not affected by the presence of specific inhibitors. The P app of aspalathin was also not affected by constituents of aspalathin-enriched rooibos extracts, but was affected by high glucose concentration (20.5 mM), which decreased the P app value to 2.9 × 10 -7 cm/s. Aspalathin metabolites (sulphated, glucuronidated and methylated) were found in mouse urine, but not in blood, following an oral dose of 50 mg/kg body weight of the pure compound. Sulphates were the predominant metabolites. These findings suggest that aspalathin is absorbed and metabolised in mice to mostly sulphate conjugates detected in urine. Mechanistically, we showed that aspalathin is not actively transported by the glucose transporters, but presumably passes the monolayer paracellularly.

LX4211 increases serum glucagon-like peptide 1 and peptide YY levels by reducing sodium/glucose cotransporter 1 (SGLT1)-mediated absorption of intestinal glucose.

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Powell, David R; Smith, Melinda; Greer, Jennifer; Harris, Angela; Zhao, Sharon; DaCosta, Christopher; Mseeh, Faika; Shadoan, Melanie K; Sands, Arthur; Zambrowicz, Brian; Ding, Zhi-Ming

2013-05-01

LX4211 [(2S,3R,4R,5S,6R)-2-(4-chloro-3-(4-ethoxybenzyl)phenyl)-6-(methylthio)tetrahydro-2H-pyran-3,4,5-triol], a dual sodium/glucose cotransporter 1 (SGLT1) and SGLT2 inhibitor, is thought to decrease both renal glucose reabsorption by inhibiting SGLT2 and intestinal glucose absorption by inhibiting SGLT1. In clinical trials in patients with type 2 diabetes mellitus (T2DM), LX4211 treatment improved glycemic control while increasing circulating levels of glucagon-like peptide 1 (GLP-1) and peptide YY (PYY). To better understand how LX4211 increases GLP-1 and PYY levels, we challenged SGLT1 knockout (-/-) mice, SGLT2-/- mice, and LX4211-treated mice with oral glucose. LX4211-treated mice and SGLT1-/- mice had increased levels of plasma GLP-1, plasma PYY, and intestinal glucose during the 6 hours after a glucose-containing meal, as reflected by area under the curve (AUC) values, whereas SGLT2-/- mice showed no response. LX4211-treated mice and SGLT1-/- mice also had increased GLP-1 AUC values, decreased glucose-dependent insulinotropic polypeptide (GIP) AUC values, and decreased blood glucose excursions during the 6 hours after a challenge with oral glucose alone. However, GLP-1 and GIP levels were not increased in LX4211-treated mice and were decreased in SGLT1-/- mice, 5 minutes after oral glucose, consistent with studies linking decreased intestinal SGLT1 activity with reduced GLP-1 and GIP levels 5 minutes after oral glucose. These data suggest that LX4211 reduces intestinal glucose absorption by inhibiting SGLT1, resulting in net increases in GLP-1 and PYY release and decreases in GIP release and blood glucose excursions. The ability to inhibit both intestinal SGLT1 and renal SGLT2 provides LX4211 with a novel dual mechanism of action for improving glycemic control in patients with T2DM.

The effect of gastric inhibitory polypeptide on intestinal glucose absorption and intestinal motility in mice

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Eiichi [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Hosokawa, Masaya [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Faculty of Human Sciences, Tezukayama Gakuin University, Osaka (Japan); Harada, Norio; Yamane, Shunsuke; Hamasaki, Akihiro; Toyoda, Kentaro; Fujimoto, Shimpei; Fujita, Yoshihito; Fukuda, Kazuhito [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Tsukiyama, Katsushi; Yamada, Yuichiro [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Department of Internal Medicine, Division of Endocrinology, Diabetes and Geriatric Medicine, Akita University School of Medicine, Akita (Japan); Seino, Yutaka [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); Kansai Electric Power Hospital, Osaka (Japan); Inagaki, Nobuya, E-mail: inagaki@metab.kuhp.kyoto-u.ac.jp [Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University (Japan); CREST of Japan Science and Technology Cooperation (JST), Kyoto (Japan)

2011-01-07

Research highlights: {yields} Exogenous GIP inhibits intestinal motility through a somatostatin-mediated pathway. {yields} Exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility. {yields} The GIP-receptor-mediated action in intestine does not involve in GLP-1-mediated pathway. -- Abstract: Gastric inhibitory polypeptide (GIP) is released from the small intestine upon meal ingestion and increases insulin secretion from pancreatic {beta} cells. Although the GIP receptor is known to be expressed in small intestine, the effects of GIP in small intestine are not fully understood. This study was designed to clarify the effect of GIP on intestinal glucose absorption and intestinal motility. Intestinal glucose absorption in vivo was measured by single-pass perfusion method. Incorporation of [{sup 14}C]-glucose into everted jejunal rings in vitro was used to evaluate the effect of GIP on sodium-glucose co-transporter (SGLT). Motility of small intestine was measured by intestinal transit after oral administration of a non-absorbed marker. Intraperitoneal administration of GIP inhibited glucose absorption in wild-type mice in a concentration-dependent manner, showing maximum decrease at the dosage of 50 nmol/kg body weight. In glucagon-like-peptide-1 (GLP-1) receptor-deficient mice, GIP inhibited glucose absorption as in wild-type mice. In vitro examination of [{sup 14}C]-glucose uptake revealed that 100 nM GIP did not change SGLT-dependent glucose uptake in wild-type mice. After intraperitoneal administration of GIP (50 nmol/kg body weight), small intestinal transit was inhibited to 40% in both wild-type and GLP-1 receptor-deficient mice. Furthermore, a somatostatin receptor antagonist, cyclosomatostatin, reduced the inhibitory effect of GIP on both intestinal transit and glucose absorption in wild-type mice. These results demonstrate that exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility through a somatostatin

The effect of gastric inhibitory polypeptide on intestinal glucose absorption and intestinal motility in mice

International Nuclear Information System (INIS)

Ogawa, Eiichi; Hosokawa, Masaya; Harada, Norio; Yamane, Shunsuke; Hamasaki, Akihiro; Toyoda, Kentaro; Fujimoto, Shimpei; Fujita, Yoshihito; Fukuda, Kazuhito; Tsukiyama, Katsushi; Yamada, Yuichiro; Seino, Yutaka; Inagaki, Nobuya

2011-01-01

Research highlights: → Exogenous GIP inhibits intestinal motility through a somatostatin-mediated pathway. → Exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility. → The GIP-receptor-mediated action in intestine does not involve in GLP-1-mediated pathway. -- Abstract: Gastric inhibitory polypeptide (GIP) is released from the small intestine upon meal ingestion and increases insulin secretion from pancreatic β cells. Although the GIP receptor is known to be expressed in small intestine, the effects of GIP in small intestine are not fully understood. This study was designed to clarify the effect of GIP on intestinal glucose absorption and intestinal motility. Intestinal glucose absorption in vivo was measured by single-pass perfusion method. Incorporation of [ 14 C]-glucose into everted jejunal rings in vitro was used to evaluate the effect of GIP on sodium-glucose co-transporter (SGLT). Motility of small intestine was measured by intestinal transit after oral administration of a non-absorbed marker. Intraperitoneal administration of GIP inhibited glucose absorption in wild-type mice in a concentration-dependent manner, showing maximum decrease at the dosage of 50 nmol/kg body weight. In glucagon-like-peptide-1 (GLP-1) receptor-deficient mice, GIP inhibited glucose absorption as in wild-type mice. In vitro examination of [ 14 C]-glucose uptake revealed that 100 nM GIP did not change SGLT-dependent glucose uptake in wild-type mice. After intraperitoneal administration of GIP (50 nmol/kg body weight), small intestinal transit was inhibited to 40% in both wild-type and GLP-1 receptor-deficient mice. Furthermore, a somatostatin receptor antagonist, cyclosomatostatin, reduced the inhibitory effect of GIP on both intestinal transit and glucose absorption in wild-type mice. These results demonstrate that exogenous GIP inhibits intestinal glucose absorption by reducing intestinal motility through a somatostatin-mediated pathway rather

Genetic and biochemical analysis of peptide transport in Escherichia coli

International Nuclear Information System (INIS)

Andrews, J.C.

1986-01-01

E. coli peptide transport mutants have been isolated based on their resistance to toxic tripeptides. These genetic defects were found to map in two distinct chromosomal locations. The transport systems which require expression of the trp-linked opp genes and the oppE gene(s) for activity were shown to have different substrate preferences. Growth of E. coli in medium containing leucine results in increased entry of exogenously supplied tripeptides into the bacterial cell. This leucine-mediated elevation of peptide transport required expression of the trp-linked opp operon and was accompanied by increased sensitivity to toxic tripeptides, by an enhanced capacity to utilize nutritional peptides, and by an increase in both the velocity and apparent steady-state level of L-(U- 14 C)alanyl-L-alanyl-L-alanine accumulation for E. coli grown in leucine-containing medium relative to these parameters of peptide transport measured with bacteria grown in media lacking leucine. Direct measurement of opp operon expression by pulse-labeling experiments demonstrated that growth of E. coli in the presence of leucine resulted in increased synthesis of the oppA-encoded periplasmic binding protein. The transcriptional regulation of the trp-linked opp operon of E. coli was investigated using λ placMu51-generated lac operon fusions. Synthesis of β-galactosidase by strains harboring oppA-lac, oppB-lac, and oppD-lac fusions occurred at a basal level when the fusion-containing strains were grown in minimal medium

Deficiency of the intestinal growth factor, glucagon-like peptide 2, in the colon of SCID mice with inflammatory bowel disease induced by transplantation of CD4+ T cells

DEFF Research Database (Denmark)

Schmidt, P T; Hartmann, B; Bregenholt, S

2000-01-01

Glucagon-like peptide 2 (GLP-2) is produced in endocrine L-cells of the intestinal mucosa. Recently, GLP-2 was found to stimulate intestinal mucosal growth. Our objective was to study the content of GLP-2 in the large intestine in a murine model of T-cell-induced inflammatory bowel disease....

Mechanisms of calcium transport in small intestine. Overall review of the contract, September 1, 1972--March 1, 1976

Energy Technology Data Exchange (ETDEWEB)

DeLuca, H.F.

1976-01-01

Progress is reported in the following areas of research: role of high molecular weight protein in calcium transport in vitamin D deficient chicks; subcellular localization of 1,25-(OH)/sub 2/D/sub 3/; receptor proteins for 1,25-(OH)/sub 2/D/sub 3/; effects of high calcium diet, strontium diet, EHDP, and parathyroidectomy on intestinal calcium transport in chicks; effects of analogs of 1,25-(OH)/sub 2/D/sub 3/ on intestinal calcium transport; discrimination by chicks against vitamin D/sub 2/ compounds by metabolism; effects of extract of Solanum malacoxylan on intestinal calcium absorption in nephrectomized rats; and role of vitamin D in phosphate transport reactions in the intestine. (HLW)

Extra-Renal Elimination of Uric Acid via Intestinal Efflux Transporter BCRP/ABCG2

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Hosomi, Atsushi; Nakanishi, Takeo; Fujita, Takuya; Tamai, Ikumi

2012-01-01

Urinary excretion accounts for two-thirds of total elimination of uric acid and the remainder is excreted in feces. However, the mechanism of extra-renal elimination is poorly understood. In the present study, we aimed to clarify the mechanism and the extent of elimination of uric acid through liver and intestine using oxonate-treated rats and Caco-2 cells as a model of human intestinal epithelium. In oxonate-treated rats, significant amounts of externally administered and endogenous uric acid were recovered in the intestinal lumen, while biliary excretion was minimal. Accordingly, direct intestinal secretion was thought to be a substantial contributor to extra-renal elimination of uric acid. Since human efflux transporter BCRP/ABCG2 accepts uric acid as a substrate and genetic polymorphism causing a decrease of BCRP activity is known to be associated with hyperuricemia and gout, the contribution of rBcrp to intestinal secretion was examined. rBcrp was confirmed to transport uric acid in a membrane vesicle study, and intestinal regional differences of expression of rBcrp mRNA were well correlated with uric acid secretory activity into the intestinal lumen. Bcrp1 knockout mice exhibited significantly decreased intestinal secretion and an increased plasma concentration of uric acid. Furthermore, a Bcrp inhibitor, elacridar, caused a decrease of intestinal secretion of uric acid. In Caco-2 cells, uric acid showed a polarized flux from the basolateral to apical side, and this flux was almost abolished in the presence of elacridar. These results demonstrate that BCRP contributes at least in part to the intestinal excretion of uric acid as extra-renal elimination pathway in humans and rats. PMID:22348008

Epidermal growth factor inhibits glycyl sarcosine transport and hPepT1 expression in a human intestinal cell line

DEFF Research Database (Denmark)

Nielsen, Carsten Uhd; Amstrup, Jan; Steffansen, Bente

2001-01-01

Intestinal oligopeptide transporter, growth factor, immunocytochemistry, laser scanning confocal microscopy......Intestinal oligopeptide transporter, growth factor, immunocytochemistry, laser scanning confocal microscopy...

Mechanistic studies of a cell-permeant peptide designed to enhance myosin light chain phosphorylation in polarized intestinal epithelia.

Science.gov (United States)

Almansour, Khaled; Taverner, Alistair; Eggleston, Ian M; Mrsny, Randall J

2018-06-10

Tight junction (TJ) structures restrict the movement of solutes between adjacent epithelial cells to maintain homeostatic conditions. A peptide, termed PIP 640, with the capacity to regulate the transient opening of intestinal TJ structures through an endogenous mechanism involving the induction of myosin light chain (MLC) phosphorylation at serine 19 (MLC-pS 19 ) has provided a promising new method to enhance the in vivo oral bioavailability of peptide therapeutics. PIP 640 is a decapeptide composed of all D-amino acids (rrdykvevrr-NH 2 ) that contains a central sequence designed to emulates a specific domain of C-kinase potentiated protein phosphatase-1 inhibitor-17 kDa (CPI-17) surrounded by positively-charged amino acids that provide a cell penetrating peptide (CPP)-like character. Here, we examine compositional requirements of PIP 640 with regard to its actions on MLC phosphorylation, its intracellular localization to TJ structures, and its interactions with MLC phosphatase (MLCP) elements that correlate with enhanced solute uptake. These studies showed that a glutamic acid and tyrosine within this peptide are critical for PIP 640 to retain its ability to increase MLC-pS 19 levels and enhance the permeability of macromolecular solutes of the size range of therapeutic peptides without detectable cytotoxicity. On the other hand, exchange of the aspartic acid for alanine and then arginine resulted in an increasingly greater bias toward protein phosphatase-1 (PP1) relative to MLCP inhibition, an outcome that resulted in increased paracellular permeability for solutes in the size range of therapeutic peptides, but with a significant increase in cytotoxicity. Together, these data further our understanding of the composition requirements of PIP 640 with respect to the desired goal of transiently altering the intestinal epithelial cell paracellular barrier properties through an endogenous mechanism, providing a novel approach to enhance the oral bioavailability of

Vasoactive intestinal peptide and secretin: effects of combined and separate intravenous infusions on bile secretion in man

International Nuclear Information System (INIS)

Nyberg, B.; Sonnenfeld, T.; Einarsson, K.

1991-01-01

The effects of intravenously administered vasoactive intestinal peptide (VIP) and secretin on bile secretion were studied in 12 patients with complete biliary fistulas. The two peptides were administered both simultaneously and separately. During VIP infusion, bile volume increased by 60%, and during the combined VIP and secretin infursion bile volume increased by another 70%. VIP increased bile bicarbonate concentration by some 30%. Although secretin did not increase the concentration, bicarbonate output increased threefold during secretin infusion but only twofold during VIP infusion. The outputs of bile acids were not significantly affected by the two peptides, whereas the concentration decreased by 40% and 70% after VIP and secretin, respectively. The canalicular bile flow, measured by [ 14 C]erythritol, was unaffected by VIP infusion, whereas secretin alone and the combination of the two peptides increased the canalicular clearance by 80%. The choleretic effect of VIP thus seems to occur only at the ductular level. Secretin exerts its effect at the ductular level and possibly also at the canalicular level. It is concluded that the two peptides have additive effects on the ductular bile flow.. 32 refs., 5 figs., 5 tabs

Fundamental and clinical evaluation of vasoactive intestinal peptide (VIP) in pancreatitis by radioimmunoassay kit

International Nuclear Information System (INIS)

Uehara, Soichiro; Nakamura, Takayuki; Ihara, Kenichi; Isogawa, Shin; Hirayama, Akio

1987-01-01

Plasma vasoactive intestinal peptide (VIP) concentrations of normal individuals and patients with pancreatitis were studied using a VIP RIA kit. The inter-assay and intra-assay variation of this kit were between 2.1 and 9.4 %. The VIP levels increased in the acute phase of acute pancreatitis and patients with chronic pancreatitis. The VIP concentration increased during the first 30 min of glucose tolerance test, but this increase was much smaller than that in insulin. These results suggest that this kit is useful for physiologic and pathologic changes in the VIP level. (author)

Intestinal transport and metabolism of bile acids

Science.gov (United States)

Dawson, Paul A.; Karpen, Saul J.

2015-01-01

In addition to their classical roles as detergents to aid in the process of digestion, bile acids have been identified as important signaling molecules that function through various nuclear and G protein-coupled receptors to regulate a myriad of cellular and molecular functions across both metabolic and nonmetabolic pathways. Signaling via these pathways will vary depending on the tissue and the concentration and chemical structure of the bile acid species. Important determinants of the size and composition of the bile acid pool are their efficient enterohepatic recirculation, their host and microbial metabolism, and the homeostatic feedback mechanisms connecting hepatocytes, enterocytes, and the luminal microbiota. This review focuses on the mammalian intestine, discussing the physiology of bile acid transport, the metabolism of bile acids in the gut, and new developments in our understanding of how intestinal metabolism, particularly by the gut microbiota, affects bile acid signaling. PMID:25210150

Transport mechanism of lipid covered saquinavir pure drug nanoparticles in intestinal epithelium

DEFF Research Database (Denmark)

Xia, Dengning; He, Yuan; Li, Qiuxia

2018-01-01

are transported. To improve cellular uptake and transport of pure nanodrug in cells, here, a lipid covered saquinavir (SQV) pure drug NP (Lipo@nanodrug) was designed by modifying a pure SQV NP (nanodrug) with a phospholipid bilayer. We studied their endocytosis, intracellular trafficking mechanism using Caco-2...... their intracellular processing, helping to improve drug transport across intestinal epithelium. To our knowledge, this is the first presentation of the novel phospholipid bilayer covered SQV pure drug NP design, and a mechanistic study on intracellular trafficking in in vitro cell models has been described......Pure drug nanoparticles (NPs) represent a promising formulation for improved drug solubility and controlled dissolution velocity. However, limited absorption by the intestinal epithelium remains challenge to their clinical application, and little is known about how these NPs within the cells...

Development of intestinal ion-transporting mechanisms during smoltification and seawater acclimation in Atlantic salmon Salmo salar

Science.gov (United States)

Sundh, Henrik; Nilsen, Tom O.; Lindström, Jenny; Hasselberg-Frank, Linda; Stefansson, Sigurd O.; McCormick, Stephen D.; Sundell, K.

2014-01-01

This study investigated the expression of ion transporters involved in intestinal fluid absorption and presents evidence for developmental changes in abundance and tissue distribution of these transporters during smoltification and seawater (SW) acclimation of Atlantic salmonSalmo salar. Emphasis was placed on Na+, K+-ATPase (NKA) and Na+, K+, Cl− co-transporter (NKCC) isoforms, at both transcriptional and protein levels, together with transcription of chloride channel genes. The nka α1c was the dominant isoform at the transcript level in both proximal and distal intestines; also, it was the most abundant isoform expressed in the basolateral membrane of enterocytes in the proximal intestine. This isoform was also abundantly expressed in the distal intestine in the lower part of the mucosal folds. The protein expression of intestinal Nkaα1c increased during smoltification. Immunostaining was localized to the basal membrane of the enterocytes in freshwater (FW) fish, and re-distributed to a lateral position after SW entry. Two other Nka isoforms, α1a and α1b, were expressed in the intestine but were not regulated to the same extent during smoltification and subsequent SW transfer. Their localization in the intestinal wall indicates a house-keeping function in excitatory tissues. The absorptive form of the NKCC-like isoform (sub-apically located NKCC2 and/or Na+, Cl−co-transporter) increased during smoltification and further after SW transfer. The cellular distribution changed from a diffuse expression in the sub-apical regions during smoltification to clustering of the transporters closer to the apical membrane after entry to SW. Furthermore, transcript abundance indicates that the mechanisms necessary for exit of chloride ions across the basolateral membrane and into the lateral intercellular space are present in the form of one or more of three different chloride channels: cystic fibrosis transmembrane conductance regulator I and II and chloride channel

Carrier-mediated system for transport of biotin in rat intestine in vitro

International Nuclear Information System (INIS)

Said, H.M.; Redha, R.

1987-01-01

Transport of biotin was examined in rat intestine using the everted sac technique. Transport of 0.1 μM biotin was linear with time for at least 30 min of incubation and occurred at a rate 3.7 pmol g initial tissue wet wt -1 min -1 . Transport of biotin was higher in the jejunum than the ileum and was minimum in the colon (85 +/- 6, 36 +/- 6, and 2.8 +/- 0.6 pmol x g initial tissue wet wt -1 x 25 min -1 , respectively). In the jejunum, transport of biotin was saturable at low concentrations but linear at higher concentrations. The transport of low concentrations of biotin was 1) inhibited by structural analogues (desthiobiotin, biotin methyl ester, diaminobiotin, and biocytin), 2) Na + dependent, 3) energy dependent, 4) temperature dependent, and 5) proceeded against a concentration gradient in the serosal compartment. No metabolic alteration occurs to the biotin molecule during transport. This study demonstrates that biotin transport in rat intestine occurs by a carrier-mediated process at low concentrations and by simple diffusion at high concentrations. Furthermore, the carrier-mediated process is Na + , energy, and temperature dependent

Changes in the transcriptional profile of transporters in the intestine along the anterior-posterior and crypt-villus axes

Directory of Open Access Journals (Sweden)

Delorenzi Mauro

2005-05-01

Full Text Available Abstract Background The purpose of this work was to characterize the expression of drug and nutrient carriers along the anterior-posterior and crypt-villus axes of the intestinal epithelium and to study the validity of utilizing whole gut tissue rather than purified epithelial cells to examine regional variations in gene expression. Results We have characterized the mRNA expression profiles of 76 % of all currently known transporters along the anterior-posterior axis of the gut. This is the first study to describe the expression profiles of the majority of all known transporters in the intestine. The expression profiles of transporters, as defined according to the Gene Ontology consortium, were measured in whole tissue of the murine duodenum, jejunum, ileum and colon using high-density microarrays. For nine transporters (Abca1, Abcc1, Abcc3, Abcg8, Slc10a2, Slc28a2, Slc2a1, Slc34a2 and Slc5a8, the mRNA profiles were further measured by RT-PCR in laser micro-dissected crypt and villus epithelial cells corresponding to the aforementioned intestinal regions. With respect to differentially regulated transporters, the colon had a distinct expression profile from small intestinal segments. The majority (59 % for p cutoff ≤ 0.05 of transporter mRNA levels were constant across the intestinal sections studied. For the transporter subclass "carrier activity", which contains the majority of known carriers for biologically active compounds, a significant change (p ≤ 0.05 along the anterior-posterior axis was observed. Conclusion All nine transporters examined in laser-dissected material demonstrated good replication of the region-specific profiles revealed by microarray. Furthermore, we suggest that the distribution characteristics of Slc5a8 along the intestinal tract render it a suitable candidate carrier for monocarboxylate drugs in the posterior portion of the intestine. Our findings also predict that there is a significant difference in the

Anti-allergic effects of a nonameric peptide isolated from the intestine gastrointestinal digests of abalone (Haliotis discus hannai) in activated HMC-1 human mast cells.

Science.gov (United States)

Ko, Seok-Chun; Lee, Dae-Sung; Park, Won Sun; Yoo, Jong Su; Yim, Mi-Jin; Qian, Zhong-Ji; Lee, Chang-Min; Oh, Junghwan; Jung, Won-Kyo; Choi, Il-Whan

2016-01-01

The aim of the present study was to examine whether the intestine gastrointestinal (GI) digests of abalone [Haliotis discus hannai (H. discus hannai)] modulate inflammatory responses and to elucidate the mechanisms involved. The GI digests of the abalone intestines were fractionated into fractions I (>10 kDa), II (5-10 kDa) and Ⅲ (abalone intestine GI digests (AIGIDs), fraction Ⅲ inhibited the passive cutaneous anaphylaxis (PCA) reaction in mice. Subsequently, a bioactive peptide [abalone intestine GI digest peptide (AIGIDP)] isolated from fraction Ⅲ was determined to be 1175.2 Da, and the amino acid sequence was found to be PFNQGTFAS. We noted that the purified nonameric peptide (AIGIDP) attenuated the phorbol‑12‑myristate 13-acetate plus calcium ionophore A23187 (PMACI)-induced histamine release and the production of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 in human mast cells (HMC-1 cells). In addition, we also noted that AIGIDP inhibited the PMACI‑induced activation of nuclear factor‑κB (NF-κB) by suppressing IκBα phosphorylation and that it suppressed the production of cytokines by decreasing the phosphorylation of JNK. The findings of our study indicate that AIGIDP exerts a modulatory, anti-allergic effect on mast cell-mediated inflammatory diseases.

Peptide Selectivity of the Proton-Coupled Oligopeptide Transporter from Neisseria meningitidis

DEFF Research Database (Denmark)

Sharma, Neha; Aduri, Nanda G; Iqbal, Anna

2016-01-01

POT). It has been shown that the gene encoding this transporter is upregulated during infection. NmPOT conformed to the typical chain length preference as observed in prototypical transporters of this family. In contrast to prototypical transporters, it was unable to accommodate a positively charged peptide...

The Ussing Chamber Assay to Study Drug Metabolism and Transport in the Human Intestine.

Science.gov (United States)

Kisser, Beatrice; Mangelsen, Eva; Wingolf, Caroline; Partecke, Lars Ivo; Heidecke, Claus-Dieter; Tannergren, Christer; Oswald, Stefan; Keiser, Markus

2017-06-22

The Ussing chamber is an old but still powerful technique originally designed to study the vectorial transport of ions through frog skin. This technique is also used to investigate the transport of chemical agents through the intestinal barrier as well as drug metabolism in enterocytes, both of which are key determinants for the bioavailability of orally administered drugs. More contemporary model systems, such as Caco-2 cell monolayers or stably transfected cells, are more limited in their use compared to the Ussing chamber because of differences in expression rates of transporter proteins and/or metabolizing enzymes. While there are limitations to the Ussing chamber assay, the use of human intestinal tissue remains the best laboratory test for characterizing the transport and metabolism of compounds following oral administration. Detailed in this unit is a step-by-step protocol for preparing human intestinal tissue, for designing Ussing chamber experiments, and for analyzing and interpreting the findings. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

An Investigation into the Gastrointestinal Stability of Exenatide in the Presence of Pure Enzymes, Everted Intestinal Rings and Intestinal Homogenates.

Science.gov (United States)

Sun, Yanan; Wang, Mengshu; Sun, Bingxue; Li, Feng; Liu, Shubo; Zhang, Yong; Zhou, Yan; Chen, Yan; Kong, Wei

2016-01-01

The purpose of this study was to investigate the gastrointestinal stability of exenatide to determine the key factor(s) contributing to peptide degradation during the oral delivery process. The effects of pH and various digestive enzymes on the degradation kinetics of exenatide were determined. Moreover, the degradation clearances of peptide were also examined using rat everted intestinal rings and intestinal homogenates from various intestinal locations. Exenatide was comparatively stable within a pH range of 1.2-8. However, obvious degradation was observed in the presence of digestive enzymes. The order of enzymes, in terms of ability to degradate exenatide, was chymotrypsin>aminopeptidase N>carboxypeptidase A>trypsin>pepsin. Chymotrypsin showed the greatest ability to degrade exenatide (half-life t1/2, 5.784×10(-2) h), whereas aminopeptidase N and carboxylpeptidase A gave t1/2 values of 3.53 and 10.16 h, respectively. The degradation of exenatide was found to be peptide concentration- and intestinal site-dependent, with a lower clearance in the upper part of the duodenum and the lower part of the ileum. When using intestinal homogenates as enzyme sources, the order, in terms of peptide degradation ability, was ileum>jejunum>duodenum. However, no significant difference was observed in the remaining peptide concentrations throughout 2 h of incubation, which may be due to the involvement of cytosolic enzymes. These results revealed key factors contributing to peptide degradation, and suggest that the inhibition of chymotrypsin and site-specific delivery of exenatide might be advantageous in overcoming metabolic obstacles during its oral delivery.

Interaction of coenzyme Q10 with the intestinal drug transporter P-glycoprotein.

Science.gov (United States)

Itagaki, Shirou; Ochiai, Akiko; Kobayashi, Masaki; Sugawara, Mitsuru; Hirano, Takeshi; Iseki, Ken

2008-08-27

In clinical trials, patients usually take many kinds of drugs at the same time. Thus, drug-drug interactions can often directly affect the therapeutic safety and efficacy of many drugs. Oral delivery is the most desirable means of drug administration. Changes in the activity of drug transporters may substantially influence the absorption of administered drugs from the intestine. However, there have been a few studies on food-drug interactions involving transporters. It is important to be aware of the potential of food-drug interactions and to act in order to prevent undesirable and harmful clinical consequences. Coenzyme Q10 (CoQ10) is very widely consumed by humans as a food supplement because of its recognition by the public as an important nutrient in supporting human health. Since intestinal efflux transporter P-glycoprotein (P-gp) is one of the major factors in drug-drug interactions, we focused on this transporter. We report here for the first time that CoQ10, which is widely used as a food supplement, affects the transport activity of P-gp.

Iodinated derivatives of vasoactive intestinal peptide (VIP), PHI and PHM: purification, chemical characterization and biological activity

International Nuclear Information System (INIS)

McMaster, D.; Suzuki, Y.; Rorstad, O.; Lederis, K.

1987-01-01

The iodination of vasoactive intestinal peptide (VIP) was studied, using a variety of enzymatic and chemical iodination methods. Reversed phase high performance liquid chromatography (HPLC) was used to purify the reaction products. The lactoperoxidase-glucose oxidase method gave excellent results in terms of reproducibility, iodine incorporation, and yield of the non-oxidized products [Tyr(I)10]VIP and [Tyr(I)22]VIP, and was used to prepare both 125 I and 127 I labelled derivatives. In both cases, direct application to HPLC and a single column system were used. Although the oxidized peptides [Tyr(I)10,Met(O)17]VIP and [Tyr(I)22,Met(O)17]VIP could be generated to varying degrees directly by iodination of VIP, these were most conveniently prepared by iodination of [Met(O)17]VIP. Iodinated derivatives of the homologous peptides PHI and PHM were likewise prepared by rapid, one-step HPLC procedures. The site and degree of iodination were determined by HPLC peptide mapping of tryptic digests and amino acid analyses, and in the case of [Tyr(I)10]VIP also by sequencing. The vasorelaxant activities of the iodinated peptides in bovine cerebral artery preparations did not differ significantly from those of the corresponding noniodinated peptides, with the exception of [Tyr(I)10,Met(O)17]VIP and [Tyr(I)22,Met(O)17]VIP which, unlike [Met(O)17]VIP itself, had slightly lower potency than VIP

Effects of taurine on plasma glucose concentration and active glucose transport in the small intestine.

Science.gov (United States)

Tsuchiya, Yo; Kawamata, Koichi

2017-11-01

Taurine lowers blood glucose levels and improves hyperglycemia. However, its effects on glucose transport in the small intestine have not been investigated. Here, we elucidated the effect of taurine on glucose absorption in the small intestine. In the oral glucose tolerance test, addition of 10 mmol/L taurine suppressed the increase in hepatic portal glucose concentrations. To investigate whether the suppressive effect of taurine occurs via down-regulation of active glucose transport in the small intestine, we performed an assay using the everted sac of the rat jejunum. Addition of taurine to the mucosal side of the jejunum suppressed active glucose transport via sodium-glucose cotransporter 1 (SGLT1). After elimination of chloride ions from the mucosal solution, taurine did not show suppressive effects on active glucose transport. These results suggest that taurine suppressed the increase in hepatic portal glucose concentrations via suppression of SGLT1 activity in the rat jejunum, depending on chloride ions. © 2017 Japanese Society of Animal Science.

A Safety and Dosing Study of Glucagon-Like Peptide 2 in Children With Intestinal Failure

DEFF Research Database (Denmark)

Sigalet, David L; Brindle, Mary; Boctor, Dana

2015-01-01

BACKGROUND AND AIMS: A glucagon-like peptide 2 (GLP-2) analogue is approved for adults with intestinal failure, but no studies of GLP-2 have included children. This study examined the pharmacokinetics, safety, and nutritional effects of GLP-2 in children with intestinal failure. METHODS: Native...... human GLP-2(1-33) was synthesized following good manufacturing practices. In an open-label trial, with parental consent, 7 parenteral nutrition-dependent pediatric patients were treated with subcutaneous GLP-2 (20 µg/kg/d) for 3 days (phase 1) and, if tolerated, continued for 42 days (phase 2...... nutrition. GLP-2 treatment had no effect on vital signs (blood pressure, heart rate, and temperature) and caused no significant adverse events. Peak GLP-2 levels were 380 pM (day 3) and 295 pM (day 42), with no change in half-life or endogenous GLP-2 levels. Nutritional indices showed a numeric improvement...

Autoradiographic quantification of vasoactive intestinal peptide binding sites in sections from human blood mononuclear cell pellets

Energy Technology Data Exchange (ETDEWEB)

Gutkind, J.S.; Kurihara, M.; Castren, E.; Saavedra, J.M.

1988-09-01

Quantitative autoradiographic methods were utilized to characterize specific, high-affinity vasoactive intestinal peptide binding sites (Kd = 310 +/- 60 pmol/L; Bmax = 93 +/- 11 fmol/mg protein) in frozen sections obtained from a mononuclear cell pellet derived from 20 ml of human blood. The method is at least one order of magnitude more sensitive than conventional membrane binding techniques, and it has the potential for wide applications in studies of neuropeptide, biogenic amine, and drug binding in clinical samples.

Autoradiographic quantification of vasoactive intestinal peptide binding sites in sections from human blood mononuclear cell pellets

International Nuclear Information System (INIS)

Gutkind, J.S.; Kurihara, M.; Castren, E.; Saavedra, J.M.

1988-01-01

Quantitative autoradiographic methods were utilized to characterize specific, high-affinity vasoactive intestinal peptide binding sites (Kd = 310 +/- 60 pmol/L; Bmax = 93 +/- 11 fmol/mg protein) in frozen sections obtained from a mononuclear cell pellet derived from 20 ml of human blood. The method is at least one order of magnitude more sensitive than conventional membrane binding techniques, and it has the potential for wide applications in studies of neuropeptide, biogenic amine, and drug binding in clinical samples

MDR1 P-glycoprotein transports endogenous opioid peptides

NARCIS (Netherlands)

Oude Elferink, R. P.; Zadina, J.

2001-01-01

MDR1 P-glycoprotein is generally regarded as an efflux pump for amphipathic toxic compounds. The question remains, however, whether certain endogenous compounds are also substrates for this transporter. Certain peptides have been shown to interact with MDR1 Pgp as well and we have therefore

Analysis of the Sodium Recirculation Theory of Solute Coupled Water Transport in Small Intestine

DEFF Research Database (Denmark)

Larsen, E. H.; Sørensen, Jens Nørkær; Sørensen, J. B.

2002-01-01

Our previous mathematical model of solute-coupled water transport through the intestinal epithelium is extended for dealing with electrolytes rather than electroneutral solutes. A 3Na+-2K+ pump in the lateral membranes provides the energy-requiring step for driving transjunctional and translateral......, computations predict that the concentration differences between lis and bathing solutions are small for all three ions. Nevertheless, the diffusion fluxes of the ions out of lis significantly exceed their mass transports. It is concluded that isotonic transport requires recirculation of all three ions....... The computed sodium recirculation flux that is required for isotonic transport corresponds to that estimated in experiments on toad small intestine. This result is shown to be robust and independent of whether the apical entrance mechanism for the sodium ion is a channel, a SGLT1 transporter driving inward...

In vitro characterization of cadmium transport along the gastro-intestinal tract of freshwater rainbow trout (Oncorhynchus mykiss)

International Nuclear Information System (INIS)

Klinck, Joel S.; Wood, Chris M.

2011-01-01

An in vitro gut sac technique was used to examine the mechanism(s) of cadmium (Cd) uptake along the gastro-intestinal tract (GIT) of rainbow trout (Oncorhynchus mykiss). The spatial distribution of Cd between three compartments (mucus-binding, mucosal epithelium, and transport into blood space) was determined using a modified Cortland saline containing 50 μM Cd (as CdCl 2 ) labeled with 109 Cd radiotracer. Taking into account total surface areas, the order of relative importance for total Cd uptake rate was: posterior intestine > anterior intestine > stomach > mid intestine. Cd transport was not inhibited by experimentally reducing fluid transport rates by manipulation of osmotic gradients using mannitol, but was sensitive to internal luminal pressure changes, suggesting a mechanosensitive pathway. Q 10 values (1, 11, and 19 o C) indicated a facilitated transport of Cd in the anterior- and mid-intestine. The effects of 10 mM Ca on the kinetics of Cd uptake suggest the presence of a common uptake pathway for Cd and Ca in the stomach, anterior-, and mid-intestine. Further evidence of a shared route of entry was found using three Ca channel blockers, lanthanum, verapamil, and nifedipine: both voltage-insensitive and voltage-sensitive Ca channels appear to be present in either some, or all portions of the GIT. Elevated Fe (500 μM), Mg (50 mM), and Zn (500 μM) showed varying degrees of inhibition of Cd transport depending on the compartment and segment of the GIT. Overall it appears that there are multiple sites, and mechanisms, of Cd uptake along the GIT of rainbow trout.

Proton movement and coupling in the POT family of peptide transporters.

Science.gov (United States)

Parker, Joanne L; Li, Chenghan; Brinth, Allete; Wang, Zhi; Vogeley, Lutz; Solcan, Nicolae; Ledderboge-Vucinic, Gregory; Swanson, Jessica M J; Caffrey, Martin; Voth, Gregory A; Newstead, Simon

2017-12-12

POT transporters represent an evolutionarily well-conserved family of proton-coupled transport systems in biology. An unusual feature of the family is their ability to couple the transport of chemically diverse ligands to an inwardly directed proton electrochemical gradient. For example, in mammals, fungi, and bacteria they are predominantly peptide transporters, whereas in plants the family has diverged to recognize nitrate, plant defense compounds, and hormones. Although recent structural and biochemical studies have identified conserved sites of proton binding, the mechanism through which transport is coupled to proton movement remains enigmatic. Here we show that different POT transporters operate through distinct proton-coupled mechanisms through changes in the extracellular gate. A high-resolution crystal structure reveals the presence of ordered water molecules within the peptide binding site. Multiscale molecular dynamics simulations confirm proton transport occurs through these waters via Grotthuss shuttling and reveal that proton binding to the extracellular side of the transporter facilitates a reorientation from an inward- to outward-facing state. Together these results demonstrate that within the POT family multiple mechanisms of proton coupling have likely evolved in conjunction with variation of the extracellular gate. Copyright © 2017 the Author(s). Published by PNAS.

Intestinal transport of gentamicin with a novel, glycosteroid drug transport agent

Science.gov (United States)

Axelrod, H. R.; Kim, J. S.; Longley, C. B.; Lipka, E.; Amidon, G. L.; Kakarla, R.; Hui, Y. W.; Weber, S. J.; Choe, S.; Sofia, M. J.

1998-01-01

PURPOSE: The objective was to investigate the ability of a glycosteroid (TC002) to increase the oral bioavailability of gentamicin. METHODS: Admixtures of gentamicin and TC002 were administered to the rat ileum by injection and to dogs by ileal or jejunal externalized ports, or PO. Bioavailability of gentamicin was determined by HPLC. 3H-TC002 was injected via externalized cannulas into rat ileum or jejunum, or PO and its distribution and elimination was determined. The metabolism of TC002 in rats was evaluated by solid phase extraction and HPLC analysis of plasma, urine and feces following oral or intestinal administration. RESULTS: The bioavailability of gentamicin was substantially increased in the presence of TC002 in both rats and dogs. The level of absorption was dependent on the concentration of TC002 and site of administration. Greatest absorption occurred following ileal orjejunal administration. TC002 was significantly more efficacious than sodium taurocholate, but similar in cytotoxicity. TC002 remained primarily in the GI tract following oral or intestinal administration and cleared rapidly from the body. It was only partly metabolized in the GI tract, but was rapidly and completely converted to its metabolite in plasma and urine. CONCLUSIONS: TC002 shows promise as a new drug transport agent for promoting intestinal absorption of polar molecules such as gentamicin.

Artificial neural network models for prediction of intestinal permeability of oligopeptides

Directory of Open Access Journals (Sweden)

Kim Min-Kook

2007-07-01

Full Text Available Abstract Background Oral delivery is a highly desirable property for candidate drugs under development. Computational modeling could provide a quick and inexpensive way to assess the intestinal permeability of a molecule. Although there have been several studies aimed at predicting the intestinal absorption of chemical compounds, there have been no attempts to predict intestinal permeability on the basis of peptide sequence information. To develop models for predicting the intestinal permeability of peptides, we adopted an artificial neural network as a machine-learning algorithm. The positive control data consisted of intestinal barrier-permeable peptides obtained by the peroral phage display technique, and the negative control data were prepared from random sequences. Results The capacity of our models to make appropriate predictions was validated by statistical indicators including sensitivity, specificity, enrichment curve, and the area under the receiver operating characteristic (ROC curve (the ROC score. The training and test set statistics indicated that our models were of strikingly good quality and could discriminate between permeable and random sequences with a high level of confidence. Conclusion We developed artificial neural network models to predict the intestinal permeabilities of oligopeptides on the basis of peptide sequence information. Both binary and VHSE (principal components score Vectors of Hydrophobic, Steric and Electronic properties descriptors produced statistically significant training models; the models with simple neural network architectures showed slightly greater predictive power than those with complex ones. We anticipate that our models will be applicable to the selection of intestinal barrier-permeable peptides for generating peptide drugs or peptidomimetics.

Clostridium difficile suppresses colonic vasoactive intestinal peptide associated with altered motility

Directory of Open Access Journals (Sweden)

A. Nassif

1995-01-01

Full Text Available We investigated whether Clostridium difficile toxin alters colonic tissue levels of vasoactive intestinal peptide (VIP at the expense of changes in colonic motility in the isolated perfused rabbit left colon. Colonic inflammation was induced by the intracolonic administration of 10−8 M C. difflcile toxin. Strain gauge transducers were sewn onto the serosal surface of the colon to evaluate colonic motility. C. difflcile administration produced histologic changes consistent with epithelial damage. This was associated with an increased production of prostaglandin E2 and thromboxane B2. Tissue levels of VIP but not substance P were significantly reduced. This was associated with an increased number of contractions per minute and an average force of each colonic contraction. These results suggest that tissue levels of VIP are suppressed by C. difflcile and may participate in colonic dysmotility during active inflammation.

The Noncaloric Sweetener Rebaudioside A Stimulates Glucagon-Like Peptide 1 Release and Increases Enteroendocrine Cell Numbers in 2-Dimensional Mouse Organoids Derived from Different Locations of the Intestine

NARCIS (Netherlands)

van der Wielen, Nikkie; Ten Klooster, Jean Paul; Muckenschnabl, Susanne; Pieters, Raymond; Hendriks, Henk Fj; Witkamp, Renger F; Meijerink, Jocelijn

2016-01-01

BACKGROUND: Glucagon-like peptide 1 (GLP-1) contributes to satiety and plays a pivotal role in insulin secretion and glucose homeostasis. Similar to GLP-1, peptide YY (PYY) and cholecystokinin also influence food intake. The secretion of these hormones by enteroendocrine cells along the intestine is

The noncaloric sweetener rebaudioside a stimulates glucagon-like peptide 1 release and increases enteroendocrine cell numbers in 2-dimensional mouse organoids derived from different locations of the intestine

NARCIS (Netherlands)

Wielen, van der Nikkie; Klooster, ten Jean Paul; Muckenschnabl, Susanne; Pieters, Raymond; Hendriks, Henk F.J.; Witkamp, Renger F.; Meijerink, Jocelijn

2016-01-01

Background: Glucagon-like peptide 1 (GLP-1) contributes to satiety and plays a pivotal role in insulin secretion and glucose homeostasis. Similar to GLP-1, peptide YY (PYY) and cholecystokinin also influence food intake. The secretion of these hormones by enteroendocrine cells along the intestine

In vitro characterization of cadmium transport along the gastro-intestinal tract of freshwater rainbow trout (Oncorhynchus mykiss)

Energy Technology Data Exchange (ETDEWEB)

Klinck, Joel S., E-mail: klinckjs@mcmaster.ca [Department of Biology, McMaster University, Hamilton, Ontario, L8S 4K1 (Canada); Wood, Chris M. [Department of Biology, McMaster University, Hamilton, Ontario, L8S 4K1 (Canada)

2011-03-15

An in vitro gut sac technique was used to examine the mechanism(s) of cadmium (Cd) uptake along the gastro-intestinal tract (GIT) of rainbow trout (Oncorhynchus mykiss). The spatial distribution of Cd between three compartments (mucus-binding, mucosal epithelium, and transport into blood space) was determined using a modified Cortland saline containing 50 {mu}M Cd (as CdCl{sub 2}) labeled with {sup 109}Cd radiotracer. Taking into account total surface areas, the order of relative importance for total Cd uptake rate was: posterior intestine > anterior intestine > stomach > mid intestine. Cd transport was not inhibited by experimentally reducing fluid transport rates by manipulation of osmotic gradients using mannitol, but was sensitive to internal luminal pressure changes, suggesting a mechanosensitive pathway. Q{sub 10} values (1, 11, and 19 {sup o}C) indicated a facilitated transport of Cd in the anterior- and mid-intestine. The effects of 10 mM Ca on the kinetics of Cd uptake suggest the presence of a common uptake pathway for Cd and Ca in the stomach, anterior-, and mid-intestine. Further evidence of a shared route of entry was found using three Ca channel blockers, lanthanum, verapamil, and nifedipine: both voltage-insensitive and voltage-sensitive Ca channels appear to be present in either some, or all portions of the GIT. Elevated Fe (500 {mu}M), Mg (50 mM), and Zn (500 {mu}M) showed varying degrees of inhibition of Cd transport depending on the compartment and segment of the GIT. Overall it appears that there are multiple sites, and mechanisms, of Cd uptake along the GIT of rainbow trout.

Effects of Immune Stress on Performance Parameters, Intestinal Enzyme Activity and mRNA Expression of Intestinal Transporters in Broiler Chickens

Directory of Open Access Journals (Sweden)

Y. Feng

2012-05-01

Full Text Available Immune stress is the loss of immune homeostasis caused by external forces. The purpose of this experiment was to investigate the effects of immune stress on the growth performance, small intestinal enzymes and peristalsis rate, and mRNA expression of nutrient transporters in broiler chickens. Four hundred and thirty-two 1-d-old broilers (Cobb500 were randomly assigned to four groups for treatment; each group included nine cages with 12 birds per cage. Group 1 = no vaccine (NV; Group 2 = conventional vaccine (CV; group 3 = lipopolysaccharide (LPS+conventional vaccine (LPS; group 4 = cyclophosphamide (CYP+conventional vaccine (CYP. The results demonstrated that immune stress by LPS and CYP reduced body weight gain (BWG, feed intake (FI, small intestine peristalsis rate and sIgA content in small intestinal digesta (p<0.05. However, the feed conversion ratio (FCR remained unchanged during the feeding period. LPS and CYP increased intestinal enzyme activity, relative expression of SGLT-1, CaBP-D28k and L-FABP mRNAs (p<0.05. LPS and CYP injection had a negative effect on the growth performance of healthy broiler chickens. The present study demonstrated that NV and CV could improve growth performance while enzyme activity in small intestine and relative expression of nutrient transporter mRNA of NV and CV were decreased in the conditions of a controlled rational feeding environment. It is generally recommended that broilers only need to be vaccinated for the diseases to which they might be exposed.

Effects of pig antibacterial peptides on growth performance and intestine mucosal immune of broiler chickens.

Science.gov (United States)

Bao, H; She, R; Liu, T; Zhang, Y; Peng, K S; Luo, D; Yue, Z; Ding, Y; Hu, Y; Liu, W; Zhai, L

2009-02-01

Currently, substitutions for antibiotic growth promoters in animals are attracting interest. This study investigated the effects of pig antibacterial peptides (PABP) on growth performance and small intestine mucosal immune responses in broilers. Three hundred 1-d-old Arbor Acre male broiler chickens were randomly allocated to 5 groups with 60 birds per group. The groups were control group; PABP administered in drinking water at 20 and 30 mg/L of water; or PABP supplemented in feed at 150 and 200 mg/kg of diet. The birds were fed a corn-soybean based diet for 6 wk. Chickens were weighed weekly and killed after 42 d of feeding, and growth performance was measured. Samples of the duodenum and jejunum were collected. The villus height, mucosa thickness, alkaline phosphatase activity, and numbers of secreting IgA and goblet cells were evaluated. The PABP-treated groups had greater BW and average daily gain, greater height of villus and thickness of gut mucosa, greater activity of alkaline phosphatase, higher ratio of secreting IgA, and a greater number of goblet cells compared with the control group (P<0.05). In conclusion, PABP can improve the growth performance, increase the intestinal ability to absorb nutrients, and improve the mucosal immunity of the intestine.

Intra-Amniotic Administration (Gallus gallus) of Cicer arietinum and Lens culinaris Prebiotics Extracts and Duck Egg White Peptides Affects Calcium Status and Intestinal Functionality.

Science.gov (United States)

Hou, Tao; Kolba, Nikolai; Glahn, Raymond P; Tako, Elad

2017-07-21

Calcium (Ca) is one of the most abundant inorganic elements in the human body and has many important physiological roles. Prebiotics and bioactive peptides are two important substances used to promote calcium uptake. However, the difference in mechanisms of the calcium uptake from these two supplements is not clear. By using the Gallus gallus model and the intra-amniotic administration procedure, the aim of this study was to investigate whether Ca status, intestinal functionality, and health-promoting bacterial populations were affected by prebiotics extracted from chickpea and lentil, and duck egg white peptides (DPs). Eleven groups (non-injected; 18 MΩ H₂O; 4 mmol/L CaCl₂; 50 mg/mL chickpea + 4 mmol/L CaCl₂; 50 mg/mL lentil + 4 mmol/L CaCl₂; 40 mg/mL DPs + 4 mmol/L CaCl₂; 5 mg/mL Val-Ser-Glu-Glu (VSEE) + 4 mmol/L CaCl₂; 50 mg/mL chickpea; 50 mg/mL lentil; 40 mg/mL DPs; 5 mg/mL VSEE) were utilized. Upon hatch, blood, cecum, small intestine, liver and bone were collected for assessment of serum bone alkaline phosphate level (BALP), the relative abundance of intestinal microflora, expression of Ca-related genes, brush border membrane (BBM) functional genes, and liver and bone mineral levels, respectively. The BALP level increased in the presence of lentil, DPs and VSEE ( p Prebiotics and DPs beneficially affected the intestinal microflora and duodenal villus surface area. This research expands the understanding of the prebiotics' properties of chickpea and lentil extracts, and peptides' effects on calcium metabolism and gut health.

Effect of egg storage duration and brooding temperatures on chick growth, intestine morphology and nutrient transporters.

Science.gov (United States)

Yalcin, S; Gursel, I; Bilgen, G; Horuluoglu, B H; Gucluer, G; Izzetoglu, G T

2017-10-01

The effects of egg storage duration (ESD) and brooding temperature (BT) on BW, intestine development and nutrient transporters of broiler chicks were investigated. A total of 396 chicks obtained from eggs stored at 18°C for 3 days (ESD3-18°C) or at 14°C for 14 days (ESD14-14°C) before incubation were exposed to three BTs. Temperatures were initially set at 32°C, 34°C and 30°C for control (BT-Cont), high (BT-High) and low (BT-Low) BTs, respectively. Brooding temperatures were decreased by 2°C each at days 2, 7, 14 and 21. Body weight was measured at the day of hatch, 2, 7, 14, 21, 28 and 42. Cloacal temperatures of broilers were recorded from 1 to 14 days. Intestinal morphology and gene expression levels of H+-dependent peptide transporter (PepT1) and Na-dependent glucose (SGLT1) were evaluated on the day of hatch and 14. Cloacal temperatures of chicks were affected by BTs from days 1 to 8, being the lowest for BT-Low chicks. BT-High resulted in the heaviest BWs at 7 days, especially for ESD14-14°C chicks. This result was consistent with longer villus and larger villus area of ESD14-14°C chicks at BT-High conditions. From 14 days to slaughter age, BT had no effect on broiler weight. ESD3-18°C chicks were heavier than ESD14-14°C chicks up to 28 days. The PepT1 and SGLT1 expression levels were significantly higher in ESD3-18°C chicks than ESD14-14°C on the day of hatch. There was significant egg storage by BT interaction for PepT1 and SGLT1 transporters at day 14. ESD14-14°C chicks had significantly higher expression of PepT1 and SGLT1 at BT-Low than those at BT-Cont. ESD14-14°C chicks upregulated PepT1 gene expression 1.15 and 1.57-fold at BT-High and BT-Low, respectively, compared with BT-Cont, whereas PepT1 expression was downregulated 0.67 and 0.62-fold in ESD3-18°C chicks at BT-High and BT-Low. These results indicated that pre-incubation egg storage conditions and BTs affected intestine morphology and PepT1 and SGLT1 nutrient transporters

Peptide transport through the blood-brain barrier. Final report 1 Jul 87-31 Dec 90

Energy Technology Data Exchange (ETDEWEB)

Partridge, W.M.

1991-01-15

Most neuropeptides are incapable of entering the brain from blood owing to the presence of unique anatomical structures in the brain capillary wall, which makes up the blood-brain barrier (BBB). Such neuropeptides could be introduced into the bloodstream by intranasal insufflation and, thus, could have powerful medicinal properties (e.g., Beta-endorphin for the treatment of pain, vasopressin analogues for treatment of memory, ACTH analogues for treatment of post-traumatic epilepsy), should these peptides be capable of traversing the BBB. One such strategy for peptide delivery through the BBB is the development of chimeric peptides, which is the basis of the present contract. The production of chimeric peptides involves the covalent coupling of a nontransportable peptide (e.g., Beta-endorphin, vasopressin) to a transportable vector peptide (e.g., insulin, transferrin, cationized albumin, histone). The transportable peptide is capable of penetrating the BBB via receptor-mediated or absorptive-mediated transcytosis. Therefore, the introduction of chimeric peptides allows the nontransportable peptide to traverse the BBB via a physiologic piggy back mechanism.

Inulin-enriched pasta improves intestinal permeability and modifies the circulating levels of zonulin and glucagon-like peptide 2 in healthy young volunteers.

Science.gov (United States)

Russo, Francesco; Linsalata, Michele; Clemente, Caterina; Chiloiro, Marisa; Orlando, Antonella; Marconi, Emanuele; Chimienti, Guglielmina; Riezzo, Giuseppe

2012-12-01

Apart from the intestinal environment, inulin induces physiological effects, which includes a reduction in glucose and lipid concentrations and modulation of gastrointestinal motility through the release of different peptides. We hypothesized that inulin-enriched pasta may also improve small intestine permeability in relation to zonulin and glucagon-like peptide 2 (GLP-2) levels in healthy young subjects. Twenty healthy, young male volunteers completed a randomized, double-blind crossover study consisting of a 2-week run-in period and two 5-week study periods (11% inulin-enriched or control pasta), with an 8-week washout period in between. The intestinal barrier function was assessed by lactulose-mannitol excretion in urine. Zonulin values and GLP-2 release were evaluated by enzyme-linked immunosorbent assay. In the inulin group, the urinary lactulose recovery was significantly lower than the other 2 groups. There were no significant differences in urinary mannitol levels between groups. Accordingly, the lactulose-mannitol excretion ratio was significantly decreased in the inulin-enriched pasta group compared with the other 2 groups. The inulin-enriched pasta group had significantly lower zonulin serum values and significantly higher GLP-2 basal values when compared with the baseline and control pasta groups. The dietary use of inulin-enriched pasta preserves intestinal mucosal barrier functioning and modulates circulating levels of zonulin and GLP-2, suggesting that prebiotics could be used in the prevention of gastrointestinal diseases and metabolic disorders. Copyright © 2012 Elsevier Inc. All rights reserved.

Regional Morphology and Transport of PAMAM Dendrimers Across Isolated Rat Intestinal Tissue.

Science.gov (United States)

Hubbard, Dallin; Bond, Tanner; Ghandehari, Hamidreza

2015-12-01

Intestinal permeability of PAMAM dendrimers has been observed, giving rationale for their use in oral drug delivery as potential carriers of associated molecules. This study assessed the apparent permeability coefficients (Papp) of dendrimers across isolated rat intestinal regional mucosae, along with estimation of the maximum non-toxic concentration. Caco-2 monolayers were also used to assess the comparative Papp values between isolated mucosae and cell culture models. Concentrations from 0.1 to 10 mM of anionic and cationic dendrimers were tested in mucosae to assess their Papp, membrane TEER, [(14)C]-mannitol Papp, and histology. 0.1 mM concentrations of dendrimers were assessed over 120 min in Caco-2 cell monolayers as concentrations above that were cytotoxic. Jejunal transport of dendrimers was higher than transport in colonic epithelium. Monolayer Papp values of dendrimers were comparable to those of jejunal mucosae. Mucosae exposed to dendrimer concentrations of 10 mM for 120 min caused significant reduction in TEER and changes in tissue morphology; however, G3.5 was the only analogue that caused significant TEER reduction and morphological changes at 1 mM concentrations. Transport in jejunal mucosae appears to be the greatest indicating that the small intestinal will be the most likely region to target for oral drug delivery using PAMAM dendrimers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Orexins control intestinal glucose transport by distinct neuronal, endocrine and direct epithelial pathways. : Orexins regulate intestinal glucose absorption

OpenAIRE

Ducroc, Robert; Voisin, Thierry; El Firar, Aadil; Laburthe, Marc

2007-01-01

International audience; Objective : Orexins are neuropeptides involved in energy homeostasis. We investigated the effect of orexin A (OxA) and OxB on intestinal glucose transport in the rat. Research Design and Methods : Injection of orexins led to a decrease in the blood glucose level in OGTT. Effects of orexins on glucose entry were analysed in Ussing chamber using the Na+-dependent increase in short-circuit current to quantify jejunal glucose transport. Results & Conclusions : The rapid an...

THE EXPRESSION PROFILING OF INTESTINAL NUTRIENT TRANSPORTER GENES IN RATS WITH RENAL FAILURE

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Hironori Yamamoto

2012-06-01

has been still unclear how different of the intestinal function in CKD. In this study, we demonstrated the microarray analysis of global gene expression in intestine of adenine-induced CKD rat. DNA microarray analysis using Affymextrix rat gene chip revealed that CKD caused great changes in gene expression in the rat duodenum: about 400 genes exhibited more than a two-fold change in expression level. Gene ontology analysis showed that a global regulation of genes by CKD involved in iron ion binding, alcoholic, organic acid and lipid metabolism. Furthermore, we found markedly changes of a number of intestinal transporters gene expression related to iron metabolism. These results suggest that CKD may alter some nutrient metabolism in the small intestine by modifying the expression of specific genes. The intestinal transcriptome database of CKD might be useful to develop the novel drugs or functional foods for CKD patients.

Cytotoxicity, Intestinal Transport, and Bioavailability of Dispersible Iron and Zinc Supplements

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Jae-Min Oh

2017-04-01

Full Text Available Iron or zinc deficiency is one of the most important nutritional disorders which causes health problem. However, food fortification with minerals often induces unacceptable organoleptic changes during preparation process and storage, has low bioavailability and solubility, and is expensive. Nanotechnology surface modification to obtain novel characteristics can be a useful tool to overcome these problems. In this study, the efficacy and potential toxicity of dispersible Fe or Zn supplement coated in dextrin and glycerides (SunActive FeTM and SunActive ZnTM were evaluated in terms of cytotoxicity, intestinal transport, and bioavailability, as compared with each counterpart without coating, ferric pyrophosphate (FePP and zinc oxide (ZnO nanoparticles (NPs, respectively. The results demonstrate that the cytotoxicity of FePP was not significantly affected by surface modification (SunActive FeTM, while SunActive ZnTM was more cytotoxic than ZnO-NPs. Cellular uptake and intestinal transport efficiency of SunActive FeTM were significantly higher than those of its counterpart material, which was in good agreement with enhanced oral absorption efficacy after a single-dose oral administration to rats. These results seem to be related to dissolution, particle dispersibility, and coating stability of materials depending on suspending media. Both SunActiveTM products and their counterpart materials were determined to be primarily transported by microfold (M cells through the intestinal epithelium. It was, therefore, concluded that surface modification of food fortification will be a useful strategy to enhance oral absorption efficiency at safe levels.

Impaired carbohydrate digestion and transport and mucosal dysbiosis in the intestines of children with autism and gastrointestinal disturbances.

Science.gov (United States)

Williams, Brent L; Hornig, Mady; Buie, Timothy; Bauman, Margaret L; Cho Paik, Myunghee; Wick, Ivan; Bennett, Ashlee; Jabado, Omar; Hirschberg, David L; Lipkin, W Ian

2011-01-01

Gastrointestinal disturbances are commonly reported in children with autism, complicate clinical management, and may contribute to behavioral impairment. Reports of deficiencies in disaccharidase enzymatic activity and of beneficial responses to probiotic and dietary therapies led us to survey gene expression and the mucoepithelial microbiota in intestinal biopsies from children with autism and gastrointestinal disease and children with gastrointestinal disease alone. Ileal transcripts encoding disaccharidases and hexose transporters were deficient in children with autism, indicating impairment of the primary pathway for carbohydrate digestion and transport in enterocytes. Deficient expression of these enzymes and transporters was associated with expression of the intestinal transcription factor, CDX2. Metagenomic analysis of intestinal bacteria revealed compositional dysbiosis manifest as decreases in Bacteroidetes, increases in the ratio of Firmicutes to Bacteroidetes, and increases in Betaproteobacteria. Expression levels of disaccharidases and transporters were associated with the abundance of affected bacterial phylotypes. These results indicate a relationship between human intestinal gene expression and bacterial community structure and may provide insights into the pathophysiology of gastrointestinal disturbances in children with autism.

Beta-endorphin chimeric peptides: Transport through the blood-brain barrier in vivo and cleavage of disulfide linkage by brain

International Nuclear Information System (INIS)

Pardridge, W.M.; Triguero, D.; Buciak, J.L.

1990-01-01

Water soluble peptides are normally not transported through the blood-brain barrier (BBB). Chimeric peptides may be transportable through the BBB and are formed by the covalent coupling of a nontransportable peptide to a transportable peptide vector, e.g. cationized albumin, using disulfide-based coupling reagents such as N-succinimidyl 3-[2-pyridyldithio(propionate)] (SPDP). The transcytosis of peptide into brain parenchyma, as opposed to vascular sequestration of blood-borne peptide, was quantified using an internal carotid artery perfusion/capillary depletion method. It is shown that [125I]beta-endorphin is not transported through the BBB, but is rapidly cleaved to free [125I] tyrosine via capillary peptidase. Therefore, chimeric peptide was prepared using [125I] [D-Ala2]beta-endorphin (DABE), owing to the resistance of this analogue to peptidase degradation. The [125I] DABE-cationized albumin chimeric peptide is shown to enter brain parenchyma at a rate comparable to that reported previously for unconjugated cationized albumin. When the [125I] DABE-cationized albumin chimeric peptide was incubated with rat brain homogenate at 37 C, the free [125I] DABE was liberated from the cationized albumin conjugate prior to its subsequent degradation into free [125I] tyrosine. Approximately 50% of the chimeric peptide was cleaved within 60 sec of incubation at 37 C. These studies demonstrate that (1) [125I]beta-endorphin is not transported through the BBB in its unconjugated form, (2) a [125I] DABE-cationized albumin chimeric peptide is transported through the BBB into brain parenchyma at a rate comparable to the unconjugated cationized albumin, and (3) brain contains the necessary disulfide reductases for rapid cleavage of the chimeric peptide into free beta-endorphin and this cleavage occurs before degradation of the [125I] DABE into [125I] tyrosine

Beta-endorphin chimeric peptides: Transport through the blood-brain barrier in vivo and cleavage of disulfide linkage by brain

Energy Technology Data Exchange (ETDEWEB)

Pardridge, W.M.; Triguero, D.; Buciak, J.L. (UCLA School of Medicine (USA))

1990-02-01

Water soluble peptides are normally not transported through the blood-brain barrier (BBB). Chimeric peptides may be transportable through the BBB and are formed by the covalent coupling of a nontransportable peptide to a transportable peptide vector, e.g. cationized albumin, using disulfide-based coupling reagents such as N-succinimidyl 3-(2-pyridyldithio(propionate)) (SPDP). The transcytosis of peptide into brain parenchyma, as opposed to vascular sequestration of blood-borne peptide, was quantified using an internal carotid artery perfusion/capillary depletion method. It is shown that (125I)beta-endorphin is not transported through the BBB, but is rapidly cleaved to free (125I) tyrosine via capillary peptidase. Therefore, chimeric peptide was prepared using (125I) (D-Ala2)beta-endorphin (DABE), owing to the resistance of this analogue to peptidase degradation. The (125I) DABE-cationized albumin chimeric peptide is shown to enter brain parenchyma at a rate comparable to that reported previously for unconjugated cationized albumin. When the (125I) DABE-cationized albumin chimeric peptide was incubated with rat brain homogenate at 37 C, the free (125I) DABE was liberated from the cationized albumin conjugate prior to its subsequent degradation into free (125I) tyrosine. Approximately 50% of the chimeric peptide was cleaved within 60 sec of incubation at 37 C. These studies demonstrate that (1) (125I)beta-endorphin is not transported through the BBB in its unconjugated form, (2) a (125I) DABE-cationized albumin chimeric peptide is transported through the BBB into brain parenchyma at a rate comparable to the unconjugated cationized albumin, and (3) brain contains the necessary disulfide reductases for rapid cleavage of the chimeric peptide into free beta-endorphin and this cleavage occurs before degradation of the (125I) DABE into (125I) tyrosine.

Effect of Cordyceps sinensis mycelium on serum vasoactive intestinal peptide and substance P in mice with intestinal dysbacteriosis

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Kai-zhong DONG

2015-01-01

Full Text Available Objective　To observe the effect of Cordyceps sinensis mycelium on serum vasoactive intestinal peptide (VIP and substance P (SP in mice with dysbacteriosis induced by antibiotics. Methods　Forty-eight healthy SPF BALB/c mice were randomly divided into the normal control group (normal drink, the dysbacteriosis model group (induced by oral administration of 0.5 g/L ceftriaxone sodium, the natural recovery group (oral sterile water to replace antibiotic after reproduction of dysbacteriosis, and Cordyceps sinensis mycelium treatment group (treated by intragastric administration of Cordyceps sinensis mycelium. The feces were collected without contamination, and the change in intestinal bacterial number was observed with the plate dilution method. The volatile fatty acid was detected by chromatography. The serum VIP and SP contents were assayed with enzyme linked immunosorbent assay (ELISA. Results　Compared with the normal control group, the numbers of probiotics, volatile fatty acids and serum VIP significantly decreased in the model group, while the serum SP markedly increased (P<0.01. Compared with the natural recovery group, the bacteria number, the quantities of volatile fatty acids and serum VIP significantly increased after the Cordyceps sinensis mycelium treatment, while the serum SP significantly decreased (P<0.01, P<0.05. Conclusion　Cordyceps sinensis mycelium may effectively adjust the proportion of the probiotics in the mice with dysbacteriosis, and the mechanism is apparently related to alteration in the VIP and SP. DOI: 10.11855/j.issn.0577-7402.2014.11.06

Transport, metabolism, and endosomal trafficking-dependent regulation of intestinal fructose absorption

Science.gov (United States)

Patel, Chirag; Douard, Veronique; Yu, Shiyan; Gao, Nan; Ferraris, Ronaldo P.

2015-01-01

Dietary fructose that is linked to metabolic abnormalities can up-regulate its own absorption, but the underlying regulatory mechanisms are not known. We hypothesized that glucose transporter (GLUT) protein, member 5 (GLUT5) is the primary fructose transporter and that fructose absorption via GLUT5, metabolism via ketohexokinase (KHK), as well as GLUT5 trafficking to the apical membrane via the Ras-related protein-in-brain 11 (Rab11)a-dependent endosomes are each required for regulation. Introducing fructose but not lysine and glucose solutions into the lumen increased by 2- to 10-fold the heterogeneous nuclear RNA, mRNA, protein, and activity levels of GLUT5 in adult wild-type mice consuming chow. Levels of GLUT5 were >100-fold that of candidate apical fructose transporters GLUTs 7, 8, and 12 whose expression, and that of GLUT 2 and the sodium-dependent glucose transporter protein 1 (SGLT1), was not regulated by luminal fructose. GLUT5-knockout (KO) mice exhibited no facilitative fructose transport and no compensatory increases in activity and expression of SGLT1 and other GLUTs. Fructose could not up-regulate GLUT5 in GLUT5-KO, KHK-KO, and intestinal epithelial cell-specific Rab11a-KO mice. The fructose-specific metabolite glyceraldehyde did not increase GLUT5 expression. GLUT5 is the primary transporter responsible for facilitative absorption of fructose, and its regulation specifically requires fructose uptake and metabolism and normal GLUT5 trafficking to the apical membrane.—Patel, C., Douard, V., Yu, S., Gao, N., Ferraris, R. P. Transport, metabolism, and endosomal trafficking-dependent regulation of intestinal fructose absorption. PMID:26071406

Tuning electronic transport via hepta-alanine peptides junction by tryptophan doping.

Science.gov (United States)

Guo, Cunlan; Yu, Xi; Refaely-Abramson, Sivan; Sepunaru, Lior; Bendikov, Tatyana; Pecht, Israel; Kronik, Leeor; Vilan, Ayelet; Sheves, Mordechai; Cahen, David

2016-09-27

Charge migration for electron transfer via the polypeptide matrix of proteins is a key process in biological energy conversion and signaling systems. It is sensitive to the sequence of amino acids composing the protein and, therefore, offers a tool for chemical control of charge transport across biomaterial-based devices. We designed a series of linear oligoalanine peptides with a single tryptophan substitution that acts as a "dopant," introducing an energy level closer to the electrodes' Fermi level than that of the alanine homopeptide. We investigated the solid-state electron transport (ETp) across a self-assembled monolayer of these peptides between gold contacts. The single tryptophan "doping" markedly increased the conductance of the peptide chain, especially when its location in the sequence is close to the electrodes. Combining inelastic tunneling spectroscopy, UV photoelectron spectroscopy, electronic structure calculations by advanced density-functional theory, and dc current-voltage analysis, the role of tryptophan in ETp is rationalized by charge tunneling across a heterogeneous energy barrier, via electronic states of alanine and tryptophan, and by relatively efficient direct coupling of tryptophan to a Au electrode. These results reveal a controlled way of modulating the electrical properties of molecular junctions by tailor-made "building block" peptides.

Effects of colchicine on the intestinal transport of endogenous lipid. Ultrastructural, biochemical, and radiochemical studies in fasting rats

International Nuclear Information System (INIS)

Pavelka, M.; Gangl, A.

1983-01-01

The involvement of microtubules in the transepithelial transport of exogenous lipid in intestinal absorptive cells has been suggested. Using electronmicroscopic, biochemical, and radiochemical methods, researchers have studied the effects of the antimicrotubular agent colchicine on the intestinal mucosa and on the intestinal transport of endogenous lipid of rats in the fasting state. After colchicine treatment, the concentration of triglycerides in intestinal mucosa of rats fasted for 24 h doubled, and electron microscopic studies showed a striking accumulation of lipid particles in absorptive epithelial cells of the tips of jejunal villi. These findings suggest that colchicine interferes with the intestinal transepithelial transport of endogenous lipoproteins. Additional studies, using an intraduodenal pulse injection of [ 14 C]linoleic acid, showed that colchicine does not affect the uptake of fatty acids by intestinal mucosa. However, it had divergent effects on fatty acid esterification, enhancing their incorporation into triglycerides relative to phospholipids, and caused a significant accumulation of endogenous diglycerides, triglycerides, and cholesterol esters within the absorptive intestinal epithelium. Detailed ultrastructural and morphometric studies revealed a decrease of visible microtubules, and a displacement of the smooth and rough endoplasmic reticulum and Golgi apparatus. Furthermore, it is shown that after colchicine treatment, microvilli appear at the lateral plasma membrane of intestinal absorptive cells, a change not previously reported to our knowledge. Thus, our study shows that colchicine causes significant changes in enterocyte ultrastructure and colchicine perturbs the reesterification of absorbed endogenous fatty acids and their secretion in the form of triglyceride-rich lipoproteins from the enterocyte

The indirect radioiodination of vasoactive intestinal peptide

International Nuclear Information System (INIS)

Wang Lihua; Li Junling; Yin Duanzhi; Zhang Lei; Zhang Xiuli; Wang Yongxian

2002-01-01

Objective: To seek for an effective way to acquire radiolabeled vasoactive intestinal peptide (VIP) with excellent in vivo stability. N-succinimidyl-3-iodo-125-benzoate (S 125 IB) came from radioiodination of N-succinimidyl-3-(tri-n-butylstannyl) benzoate (ATE) precursor and then conjugated with VIP to form 125 IBA-VIP. The labelling procedure was optimized; the in vitro stability and biological activity were evaluated. Methods: 1) Radiolabeling of ATE precursor was achieved with iodogen oxidant and the influential factors were considered in this procedure. The labeling efficiency was determined by thin layer chromatography (TLC) and the purification was carried out by Sep-pak silica gel cartridge. The stability was detected by TLC after 2 h storage in dark at 4 degree C. 2) Conjugation of S 125 IB and VIP. The labelling efficiency was determined with RP TLC and the purification was carried out with high performance liquid chromatography (HPLC, RP C18 column). Trichloroacetic acid (TCA) precipitation method was applied to evaluate the in vitro stability while the biological activity was determined by cell binding experiments with SGC7901 cell lines. Results: 1) S 125 IB experiments. The radioiodination of ATE was performed well for 5 min at 25 degree C with 10 micrograms of iodogen at suitable mole ratio (3-8:1) of ATE/Na 125 I, the labelling efficiency was about 96%. The stability was kept well at 4 degree C in dark, no significant decrease of S 125 IB was observed. 2) The conjugation efficiency of S 125 IB and VIP was above 75% with TLC. HPLC showed the different retention time (t R ) as follows, 125 IBA-VIP: 13.3 min, S 125 IB: 19.6 min, VIP: 8.32 min. The stability of 125 IBA-VIP was better than 125 I-VIP from direct radioiodination of VIP with iodogen oxidant, only 2.85% decrease was found after 7 d at 4 degree C. The biological activity of 125 IBA-VIP was kept as well as 125 I-VIP under the condition of 37 degree C 60 min. Conclusions: The indirect

Synergistic effect of supplemental enteral nutrients and exogenous glucagon-like peptide 2 on intestinal adaptation in a rat model of short bowel syndrome

DEFF Research Database (Denmark)

Liu, Xiaowen; Nelson, David W; Holst, Jens Juul

2006-01-01

BACKGROUND: Short bowel syndrome (SBS) can lead to intestinal failure and require total or supplemental parenteral nutrition (TPN or PN, respectively). Glucagon-like peptide 2 (GLP-2) is a nutrient-dependent, proglucagon-derived gut hormone that stimulates intestinal adaptation. OBJECTIVE: Our...... objective was to determine whether supplemental enteral nutrients (SEN) modulate the intestinotrophic response to a low dose of GLP-2 coinfused with PN in a rat model of SBS (60% jejunoileal resection plus cecectomy). DESIGN: Rats were randomly assigned to 8 treatments by using a 2 x 2 x 2 factorial design...

Receptors for vasoactive intestinal peptide in rat anterior pituitary glands: Localization of binding to lactotropes

International Nuclear Information System (INIS)

Wanke, I.E.; Rorstad, O.P.

1990-01-01

Vasoactive intestinal peptide (VIP) has been implicated as a physiological PRL-releasing factor; however, characterization of VIP receptors on normal pituitaries using radioligand-binding methods has been problematic. In this study we demonstrated specific receptors for VIP in anterior pituitary glands of female rats using HPLC-purified monoiodinated [Tyr(125I)10]VIP. Binding of VIP was reversible, saturable to receptor and radioligand, regulated by guanine nucleotides, and dependent on time and temperature. Scatchard analysis of competitive binding studies indicated high and low affinity binding sites, with equilibrium dissociation constants (Kd) of 0.19 +/- 0.03 and 28 +/- 16 nM, respectively. The corresponding maximum numbers of binding sites were 158 +/- 34 fmol/mg and 11.7 +/- 6.9 pmol/mg. Binding was specific, as peptides with structural homology to VIP were less than 100th as potent as VIP. The rank order of potency of the peptides tested was VIP greater than rat (r) peptide histidine isoleucine = human (h) PHI greater than rGRF greater than bovine GRF = porcine PHI = VIP-(10-28) greater than hGRF greater than secretin greater than apamin greater than glucagon. Radioligand binding was associated primarily with lactotrope-enriched fractions prepared by unit gravity sedimentation of dispersed anterior pituitary cells. VIP stimulated PRL release from cultured rat anterior pituitary cells, with an ED50 of 1 nM. These results, comprising the first identification of specific VIP receptors in normal rat anterior pituitary tissue using radioligand-binding methods, provide additional support for a biological role of VIP in lactotrope function

A chimeric peptide of intestinal trefoil factor containing cholesteryl ester transfer protein B cell epitope significantly inhibits atherosclerosis in rabbits after oral administration.

Science.gov (United States)

Qi, Gaofu; Li, Jingjing; Wang, Shengying; Xin, Shanshan; Du, Peng; Zhang, Qingye; Zhao, Xiuyun

2011-04-01

Vaccination against cholesteryl ester transfer protein (CETP) is proven to be effective for inhibiting atherosclerosis in animal models. In this study, the proteases-resistant intestinal trefoil factor (TFF3) was used as a molecular vehicle to construct chimeric TFF3 (cTFF3) containing CETP B cell epitope and tetanus toxin helper T cell epitope. It was found that cTFF3 still preserved a trefoil structure, and can resist proteases digestion in vitro. After oral immunization with cTFF3, the CETP-specific IgA and IgG could be found in intestine lavage fluid and serum, and the anti-CETP antibodies could inhibit partial CETP activity to increase high-density lipoprotein cholesterol, decrease low-density lipoprotein cholesterol, and inhibit atherosclerosis in animals. Therefore, TFF3 is a potential molecular vehicle for developing oral peptide vaccines. Our research highlights a novel strategy for developing oral peptide vaccines in the future. Copyright © 2010 Elsevier Inc. All rights reserved.

Design, Recombinant Fusion Expression and Biological Evaluation of Vasoactive Intestinal Peptide Analogue as Novel Antimicrobial Agent

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Chunlan Xu

2017-11-01

Full Text Available Antimicrobial peptides represent an emerging category of therapeutic agents with remarkable structural and functional diversity. Modified vasoactive intestinal peptide (VIP (VIP analogue 8 with amino acid sequence “FTANYTRLRRQLAVRRYLAAILGRR” without haemolytic activity and cytotoxicity displayed enhanced antimicrobial activities against Staphylococcus aureus (S. aureus ATCC 25923 and Escherichia coli (E. coli ATCC 25922 than parent VIP even in the presence of 180 mM NaCl or 50 mM MgCl2, or in the range of pH 4–10. VIP analogue 8 was expressed as fusion protein thioredoxin (Trx-VIP8 in E. coli BL21(DE at a yield of 45.67 mg/L. The minimum inhibitory concentration (MIC of the recombinant VIP analogue 8 against S. aureus ATCC 25923 and E. coli ATCC 25922 were 2 μM. These findings suggest that VIP analogue 8 is a promising candidate for application as a new and safe antimicrobial agent.

[Important application of intestinal transporters and metabolism enzymes on gastrointestinal disposal of active ingredients of Chinese materia medica].

Science.gov (United States)

Bi, Xiaolin; Du, Qiu; Di, Liuqing

2010-02-01

Oral drug bioavailability depends on gastrointestinal absorption, intestinal transporters and metabolism enzymes are the important factors in drug gastrointestinal absorption and they can also be induced or inhibited by the active ingredients of Chinese materia medica. This article presents important application of intestinal transporters and metabolism enzymes on gastrointestinal disposal of the active ingredients of Chinese materia medica, and points out the importance of research on transport and metabolism of the active ingredients of Chinese materia medica in Chinese extract and Chinese medicinal formulae.

Direct demonstration of guanine nucleotide sensitive receptors for vasoactive intestinal peptide in the anterior lobe of the rat pituitary gland

International Nuclear Information System (INIS)

Agui, T.; Matsumoto, K.

1990-01-01

The vasoactive intestinal peptide (VIP) receptors were identified on the membranes from the rat anterior pituitary gland with [ 125 I]VIP. The dissociation constant (Kd) and the maximal binding capacity (Bmax) values were estimated from the competitive inhibition data. The Kd and Bmax values were 1.05 +/- 0.75 nM and 103 +/- 11 fmol/mg protein, respectively. The order of molar potency of related peptides to inhibit [ 125 I]VIP binding was VIP greater than peptide histidine isoleucine (PHI) greater than secretin greater than glucagon. Glucagon was not effective to inhibit the binding. [ 125 I]VIP binding was effectively inhibited by the addition of guanine nucleotides. The order of molar potency to inhibit the binding was Gpp(NH)p greater than GTP greater than GDP greater than GMP greater than ATP. These results directly suggest the coupling of VIP receptors with guanine nucleotide binding proteins in the anterior pituitary gland

Acylation of Therapeutic Peptides

DEFF Research Database (Denmark)

Trier, Sofie; Henriksen, Jonas Rosager; Jensen, Simon Bjerregaard

) , which promotes intestinal growth and is used to treat bowel disorders such as inflammatory bowel diseases and short bowel syndrome, and the 32 amino acid salmon calcitonin (sCT), which lowers blood calcium and is employed in the treatment of post-menopausal osteoporosis and hypercalcemia. The two...... peptides are similar in size and structure, but oppositely charged at physiological pH. Both peptides were acylated with linear acyl chains of systematically increasing length, where sCT was furthermore acylated at two different positions on the peptide backbone. For GLP-2, we found that increasing acyl...... remained optimal overall. The results indicate that rational acylation of GLP-2 can increase its in vitro intestinal absorption, alone or in combination with permeation enhancers, and are consistent with the initial project hypothesis. For sCT, an unpredicted effect of acylation largely superseded...

Temperature modulates the effects of ocean acidification on intestinal ion transport in Atlantic cod, Gadus morhua

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Marian Yong-An Hu

2016-06-01

Full Text Available CO2-driven seawater acidification has been demonstrated to enhance intestinal bicarbonate secretion rates in teleosts, leading to an increased release of CaCO3 under simulated ocean acidification scenarios. In this study, we investigated if increasing CO2 levels stimulate the intestinal acid–base regulatory machinery of Atlantic cod (Gadus morhua and whether temperatures at the upper limit of thermal tolerance stimulate or counteract ion regulatory capacities. Juvenile G. morhua were acclimated for four weeks to three CO2 levels (550, 1,200 and 2,200 μatm covering present and near-future natural variability, at optimum (10°C and summer maximum temperature (18°C, respectively. Immunohistochemical analyses revealed the subcellular localization of ion transporters, including Na+/K+-ATPase (NKA, Na+/H+-exchanger 3 (NHE3, Na+/HCO3- cotransporter (NBC1, pendrin-like Cl-/HCO3- exchanger (SLC26a6, V-type H+-ATPase subunit a (VHA and Cl- channel 3 (CLC3 in epithelial cells of the anterior intestine. At 10°C, proteins and mRNA were generally up-regulated for most transporters in the intestinal epithelium after acclimation to higher CO2 levels. This supports recent findings demonstrating increased intestinal HCO3- secretion rates in response to CO2 induced seawater acidification. At 18°C, mRNA expression and protein concentrations of most ion transporters remained unchanged or were even decreased, suggesting thermal compensation. This response may be energetically favorable to retain blood HCO3- levels to stabilize pHe, but may negatively affect intestinal salt and water resorption of marine teleosts in future oceans.

Expression of host defense peptides in the intestine of Eimeria-challenged chickens.

Science.gov (United States)

Su, S; Dwyer, D M; Miska, K B; Fetterer, R H; Jenkins, M C; Wong, E A

2017-07-01

Avian coccidiosis is caused by the intracellular protozoan Eimeria, which produces intestinal lesions leading to weight gain depression. Current control methods include vaccination and anticoccidial drugs. An alternative approach involves modulating the immune system. The objective of this study was to profile the expression of host defense peptides such as avian beta-defensins (AvBDs) and liver expressed antimicrobial peptide 2 (LEAP2), which are part of the innate immune system. The mRNA expression of AvBD family members 1, 6, 8, 10, 11, 12, and 13 and LEAP2 was examined in chickens challenged with either E. acervulina, E. maxima, or E. tenella. The duodenum, jejunum, ileum, and ceca were collected 7 d post challenge. In study 1, E. acervulina challenge resulted in down-regulation of AvBD1, AvBD6, AvBD10, AvBD11, AvBD12, and AvBD13 in the duodenum. E. maxima challenge caused down-regulation of AvBD6, AvBD10, and AvBD11 in the duodenum, down-regulation of AvBD10 in the jejunum, but up-regulation of AvBD8 and AvBD13 in the ceca. E. tenella challenge showed no change in AvBD expression in any tissue. In study 2, which involved challenge with only E. maxima, there was down-regulation of AvBD1 in the ileum, AvBD11 in the jejunum and ileum, and LEAP2 in all 3 segments of the small intestine. The expression of LEAP2 was further examined by in situ hybridization in the jejunum of chickens from study 2. LEAP2 mRNA was expressed similarly in the enterocytes lining the villi, but not in the crypts of control and Eimeria challenged chickens. The lengths of the villi in the Eimeria challenged chickens were less than those in the control chickens, which may in part account for the observed down-regulation of LEAP2 mRNA quantified by PCR. Overall, the AvBD response to Eimeria challenge was not consistent; whereas LEAP2 was consistently down-regulated, which suggests that LEAP2 plays an important role in modulating an Eimeria infection. Published by Oxford University Press on

Expression of transcellular and paracellular calcium and magnesium transport proteins in renal and intestinal epithelia during lactation.

Science.gov (United States)

Beggs, Megan R; Appel, Ida; Svenningsen, Per; Skjødt, Karsten; Alexander, R Todd; Dimke, Henrik

2017-09-01

Significant alterations in maternal calcium (Ca 2+ ) and magnesium (Mg 2+ ) balance occur during lactation. Ca 2+ is the primary divalent cation mobilized into breast milk by demineralization of the skeleton and alterations in intestinal and renal Ca 2+ transport. Mg 2+ is also concentrated in breast milk, but the underlying mechanisms are not well understood. To determine the molecular alterations in Ca 2+ and Mg 2+ transport in the intestine and kidney during lactation, three groups of female mice consisting of either nonpregnant controls, lactating mice, or mice undergoing involution were examined. The fractional excretion of Ca 2+ , but not Mg 2+ , rose significantly during lactation. Renal 1-α hydroxylase and 24-OHase mRNA levels increased markedly, as did plasma 1,25 dihydroxyvitamin D levels. This was accompanied by significant increases in intestinal expression of Trpv6 and S100g in lactating mice. However, no alterations in the expression of cation-permeable claudin-2, claudin-12, or claudins-15 were found in the intestine. In the kidney, increased expression of Trpv5 and Calb1 was observed during lactation, while no changes in claudins involved in Ca 2+ and Mg 2+ transport (claudin-2, claudin-14, claudin-16, or claudin-19) were found. Consistent with the mRNA expression, expression of both calbindin-D 28K and transient receptor potential vanilloid 5 (TRPV5) proteins increased. Colonic Trpm6 expression increased during lactation, while renal Trpm6 remained unaltered. In conclusion, proteins involved in transcellular Ca 2+ and Mg 2+ transport pathways increase during lactation, while expression of paracellular transport proteins remained unchanged. Increased fractional Ca 2+ excretion can be explained by vitamin D-dependent intestinal hyperabsorption and bone demineralization, despite enhanced transcellular Ca 2+ uptake by the kidney. Copyright © 2017 the American Physiological Society.

Bone resorption is decreased postprandially by intestinal factors and glucagon-like peptide-2 is a possible candidate

DEFF Research Database (Denmark)

Holst, Jens Juul; Hartmann, Bolette; Gottschalck, Ida B

2007-01-01

-bowel syndrome (SBS) or total gastrectomy in order to elucidate whether the signal for the meal-induced reduction of bone resorption is initiated from the stomach or the intestine. MATERIAL AND METHODS: Bone resorption was assessed from the serum concentration of collagen type I C-telopeptide cross-links (s......OBJECTIVE: Food intake inhibits bone resorption by a mechanism thought to involve gut hormones, and the intestinotrophic glucagon-like peptide 2 (GLP-2) is a candidate because exogenous GLP-2 inhibits bone resorption in humans. The purpose of the study was to investigate patients with short...

Electrical stimulation of the isolated rat intestine in the presence of nutrient stimulus enhances glucagon-like peptide-1 release

International Nuclear Information System (INIS)

Schwartz, Ann; Ort, Tatiana; Kajekar, Radhika; Hornby, Pamela J; Wade, Paul R

2010-01-01

The release of small intestinal hormones by constituents of ingested food, such as fatty acids, is integral to post-prandial responses that reduce food intake. Recent evidence suggests that small intestinal electrical stimulation reduces food intake, although the mechanism of action is debated. To test the hypothesis that intestinal stimulation directly alters hormone release locally we used isolated rat distal ileum and measured glucagon-like peptide-1 (GLP-1) released in the presence or absence of linoleic acid (LA) and electrical field stimulation (EFS). Intact segments were oriented longitudinally between bipolar stimulating electrodes in organ bath chambers containing modified Krebs–Ringers bicarbonate (KRB) buffer including protease inhibitors. Incubation in LA (3 mg ml −1 ) for 45 min increased GLP-1 concentration (21.9 ± 2.6 pM versus KRB buffer alone 3.6 ± 0.1 pM). Eleven electrical stimulation conditions were tested. In the presence of LA none of the stimulation conditions inhibited LA-evoked GLP-1 release, whereas two high frequency short pulse widths (14 V, 20 Hz, 5 ms and 14 V, 40 Hz, 5 ms) and one low frequency long pulse width (14 V, 0.4 Hz, 300 ms) EFS conditions enhanced LA-evoked GLP-1 release by >250%. These results are consistent with a local effect of intestinal electrical stimulation to enhance GLP-1 release in response to luminal nutrients in the intestines. Enhancing hormone release could improve the efficacy of intestinal electrical stimulation and provide a potential treatment for obesity and metabolic conditions

Functional characterization of water transport and cellular localization of three aquaporin paralogs in the salmonid intestine

DEFF Research Database (Denmark)

Madsen, Steffen S; Olesen, Jesper H; Bedal, Konstanze

2011-01-01

Intestinal water absorption is greatly enhanced in salmonids upon acclimation from freshwater (FW) to seawater (SW); however, the molecular mechanism for water transport is unknown. We conducted a pharmacological characterization of water absorption in the rainbow trout intestine along......%), 0.1 ouabain (72%), and 0.1 bumetanide (82%) suggesting that active transport, Na(+), K(+)-ATPase and Na(+), K(+), 2Cl(-)-co-transport are involved in establishing the driving gradient for water transport. J(v) was also inhibited by 1 mmol L(-1) HgCl(2), serosally (23% in M and 44% in P), mucosally...... (27% in M), or both (61% in M and 58% in P), suggesting involvement of both apical and basolateral aquaporins in water transport. The inhibition was antagonized by 5 mmol L(-1) mercaptoethanol. By comparison, 10 mmol L(-1) mucosal tetraethylammonium, an inhibitor of certain aquaporins, inhibited J...

Intestinal Serotonin Transporter Inhibition by Toll-Like Receptor 2 Activation. A Feedback Modulation.

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Eva Latorre

Full Text Available TLR2 is a microbiota recognition receptor that has been described to contribute to intestinal homeostasis and to ameliorate inflammatory intestinal injury. In this context, serotonin (5-HT has shown to be an essential intestinal physiological neuromodulator that is also involved in intestinal inflammatory diseases. Since the interaction between TLR2 activation and the intestinal serotoninergic system remains non-investigated, our main aim was to analyze the effect of TLR2 on intestinal serotonin transporter (SERT activity and expression and the intracellular pathways involved. Caco-2/TC7 cells were used to analyze SERT and TLR2 molecular expression and SERT activity by measuring 5-HT uptake. The results showed that apical TLR2 activation inhibits SERT activity in Caco-2/TC7 cells mainly by reducing SERT protein level either in the plasma membrane, after short-term TLR2 activation or in both the plasma membrane and cell lysate, after long-term activation. cAMP/PKA pathway appears to mediate short-term inhibitory effect of TLR2 on SERT; however, p38 MAPK pathway has been shown to be involved in both short- and long-term TLR2 effect. Reciprocally, 5-HT long-term treatment yielded TLR2 down regulation in Caco-2/TC7 cells. Finally, results from in vivo showed an augmented intestinal SERT expression in mice Tlr2-/-, thus confirming our inhibitory effect of TLR2 on intestinal SERT in vitro. The present work infers that TLR2 may act in intestinal pathophysiology, not only by its inherent innate immune role, but also by regulating the intestinal serotoninergic system.

Expression of nutrient transporters in duodenum, jejunum, and ileum of Eimeria maxima-infected broiler chickens.

Science.gov (United States)

Fetterer, Raymond H; Miska, Katarzyna B; Jenkins, Mark C; Wong, Eric A

2014-10-01

The uptake of amino acids is mediated by active transporters located on the basolateral and brush border membranes of intestinal epithelial cells. The current study investigated the expression of amino acid transporters (AAT) and other genes in the intestine of chicks infected with Eimeria maxima. At 7-day postinfection (PI), tissue from each intestinal segment (duodenum, jejunum, and ileum) was taken from birds inoculated with 3 × 10(3) oocysts/bird and processed to recover RNA. Analysis of gene expression was performed using real-time reverse transcription polymerase chain reaction (qRT-PCR). Results were given as relative expression using β₂-microglobulin as an endogenous control. All the genes studied were expressed in three segments of the intestines, and expression of the genes was altered by infection with E. maxima. Even though the jejunum is considered the parasite's primary predilection site, there was no segment-related difference in expression of most of the genes studied. The antimicrobial peptide (LEAP2) was downregulated in all three segments of the intestine. The results also demonstrate that transporters associated with brush border membranes were downregulated while transporters associated with the basolateral membranes were upregulated and that E. maxima alters the expression of AAT and LEAP2 throughout the small intestine.

Multiple efflux pumps are involved in the transepithelial transport of colchicine: combined effect of p-glycoprotein and multidrug resistance-associated protein 2 leads to decreased intestinal absorption throughout the entire small intestine.

Science.gov (United States)

Dahan, Arik; Sabit, Hairat; Amidon, Gordon L

2009-10-01

The purpose of this study was to thoroughly characterize the efflux transporters involved in the intestinal permeability of the oral microtubule polymerization inhibitor colchicine and to evaluate the role of these transporters in limiting its oral absorption. The effects of P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP) inhibitors on colchicine bidirectional permeability were studied across Caco-2 cell monolayers, inhibiting one versus multiple transporters simultaneously. Colchicine permeability was then investigated in different regions of the rat small intestine by in situ single-pass perfusion. Correlation with the P-gp/MRP2 expression level throughout different intestinal segments was investigated by immunoblotting. P-gp inhibitors [N-(4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]-phenyl)-9,10-dihydro-5-methoxy-9-oxo-4-acridine carboxamide (GF120918), verapamil, and quinidine], and MRP2 inhibitors [3-[[3-[2-(7-chloroquinolin-2-yl)vinyl]phenyl]-(2-dimethylcarbamoylethylsulfanyl)methylsulfanyl] propionic acid (MK571), indomethacin, and p-aminohippuric acid (p-AH)] significantly increased apical (AP)-basolateral (BL) and decreased BL-AP Caco-2 transport in a concentration-dependent manner. No effect was obtained by the BCRP inhibitors fumitremorgin C (FTC) and pantoprazole. P-gp/MRP2 inhibitors combinations greatly reduced colchicine mucosal secretion, including complete abolishment of efflux (GF120918/MK571). Colchicine displayed low (versus metoprolol) and constant permeability along the rat small-intestine. GF120918 significantly increased colchicine permeability in the ileum with no effect in the jejunum, whereas MK571 augmented jejunal permeability without changing the ileal transport. The GF120918/MK571 combination caused an effect similar to that of MK571 alone in the jejunum and to that of GF120918 alone in the ileum. P-gp expression followed a gradient increasing from

A synthetic peptide shows retro- and anterograde neuronal transport before disrupting the chemosensation of plant-pathogenic nematodes.

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Dong Wang

2011-03-01

Full Text Available Cyst nematodes are a group of plant pathogens each with a defined host range that cause major losses to crops including potato, soybean and sugar beet. The infective mobile stage hatches from dormant eggs and moves a short distance through the soil to plant roots, which it then invades. A novel strategy for control has recently been proposed in which the plant is able to secrete a peptide which disorientates the infective stage and prevents invasion of the pathogen. This study provides indirect evidence to support the mechanism by which one such peptide disrupts chemosensory function in nematodes. The peptide is a disulphide-constrained 7-mer with the amino acid sequence CTTMHPRLC that binds to nicotinic acetylcholine receptors. A fluorescently tagged version of this peptide with both epifluorescent and confocal microscopy was used to demonstrate that retrograde transport occurs from an aqueous environment along bare-ending primary cilia of chemoreceptive sensilla. The peptide is transported to the cell bodies of these neurons and on to a limited number of other neurons to which they connect. It appears to be localised in both neuronal processes and organelles adjacent to nuclei of some neurons suggesting it could be transported through the Golgi apparatus. The peptide takes 2.5 h to reach the neuronal cell bodies. Comparative studies established that similar but less abundant uptake occurs for Caenorhabditis elegans along its well studied dye-filling chemoreceptive neurons. Incubation in peptide solution or root-exudate from transgenic plants that secrete the peptide disrupted normal orientation of infective cyst nematodes to host root diffusate. The peptide probably undergoes transport along the dye-filling non-cholinergic chemoreceptive neurons to their synapses where it is taken up by the interneurons to which they connect. Coordinated responses to chemoreception are disrupted when the sub-set of cholinergic interneurons secrete the peptide

A synthetic peptide shows retro- and anterograde neuronal transport before disrupting the chemosensation of plant-pathogenic nematodes.

Science.gov (United States)

Wang, Dong; Jones, Laura M; Urwin, Peter E; Atkinson, Howard J

2011-03-07

Cyst nematodes are a group of plant pathogens each with a defined host range that cause major losses to crops including potato, soybean and sugar beet. The infective mobile stage hatches from dormant eggs and moves a short distance through the soil to plant roots, which it then invades. A novel strategy for control has recently been proposed in which the plant is able to secrete a peptide which disorientates the infective stage and prevents invasion of the pathogen. This study provides indirect evidence to support the mechanism by which one such peptide disrupts chemosensory function in nematodes. The peptide is a disulphide-constrained 7-mer with the amino acid sequence CTTMHPRLC that binds to nicotinic acetylcholine receptors. A fluorescently tagged version of this peptide with both epifluorescent and confocal microscopy was used to demonstrate that retrograde transport occurs from an aqueous environment along bare-ending primary cilia of chemoreceptive sensilla. The peptide is transported to the cell bodies of these neurons and on to a limited number of other neurons to which they connect. It appears to be localised in both neuronal processes and organelles adjacent to nuclei of some neurons suggesting it could be transported through the Golgi apparatus. The peptide takes 2.5 h to reach the neuronal cell bodies. Comparative studies established that similar but less abundant uptake occurs for Caenorhabditis elegans along its well studied dye-filling chemoreceptive neurons. Incubation in peptide solution or root-exudate from transgenic plants that secrete the peptide disrupted normal orientation of infective cyst nematodes to host root diffusate. The peptide probably undergoes transport along the dye-filling non-cholinergic chemoreceptive neurons to their synapses where it is taken up by the interneurons to which they connect. Coordinated responses to chemoreception are disrupted when the sub-set of cholinergic interneurons secrete the peptide at synapses that

Vasoactive intestinal polypeptide and peptide histidine methionine. Presence in human follicular fluid and effects on DNA synthesis and steroid secretion in cultured human granulosa/lutein cells

DEFF Research Database (Denmark)

Gräs, S; Ovesen, Per Glud; Andersen, A N

1994-01-01

Vasoactive intestinal polypeptide (VIP) and peptide histidine methionine (PHM) originate from the same precursor molecule, prepro VIP. In the present study we examined the concentrations of VIP and PHM in human follicular fluid and their effects on cultured human granulosa/lutein cells. Follicula...

Glucagon-like peptides GLP-1 and GLP-2, predicted products of the glucagon gene, are secreted separately from pig small intestine but not pancreas

DEFF Research Database (Denmark)

Holst, J J; Poulsen, Steen Seier

1986-01-01

We developed specific antibodies and RIAs for glucagon-like peptides 1 and 2 (GLP-1 and GLP-2), two predicted products of the glucagon gene, and studied the occurrence, nature, and secretion of immunoreactive GLP-1 and GLP-2 in pig pancreas and small intestine. Immunoreactive GLP-1 and GLP-2 were...

Effects of exogenous glucagon-like peptide-2 and distal bowel resection on intestinal and systemic adaptive responses in rats

DEFF Research Database (Denmark)

Lai, Sarah W; de Heuvel, Elaine; Wallace, Laurie E

2017-01-01

mount immunohistochemistry for neurons (HuC/D, VIP, nNOS), plasma glucose, gut hormones, and body composition. RESULTS: Resection increased the proportion of nNOS immunopositive myenteric neurons, intestinal muscularis propria thickness and crypt cell proliferation, which were not recapitulated by GLP-2......-2 attenuated resection-induced increases in blood glucose and body fat loss. CONCLUSIONS: Exogenous GLP-2 stimulates jejunal adaptation independent of enteric neuronal VIP or nNOS changes, and has divergent effects on plasma amylin and peptide YY concentrations. The novel ability of exogenous GLP-2......OBJECTIVE: To determine the effects of exogenous glucagon-like peptide-2 (GLP-2), with or without massive distal bowel resection, on adaptation of jejunal mucosa, enteric neurons, gut hormones and tissue reserves in rats. BACKGROUND: GLP-2 is a gut hormone known to be trophic for small bowel mucosa...

H{sup +}/peptide transporter (PEPT2) is expressed in human epidermal keratinocytes and is involved in skin oligopeptide transport

Energy Technology Data Exchange (ETDEWEB)

Kudo, Michiko; Katayoshi, Takeshi; Kobayashi-Nakamura, Kumiko [DHC Corporation Laboratories, Division 2, 2-42 Hamada, Mihama-ku, Chiba 261-0025 (Japan); Akagawa, Mitsugu [Department of Biological Chemistry, Division of Applied Life Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531 (Japan); Tsuji-Naito, Kentaro, E-mail: knaito@dhc.co.jp [DHC Corporation Laboratories, Division 2, 2-42 Hamada, Mihama-ku, Chiba 261-0025 (Japan)

2016-07-08

Peptide transporter 2 (PEPT2) is a member of the proton-coupled oligopeptide transporter family, which mediates the cellular uptake of oligopeptides and peptide-like drugs. Although PEPT2 is expressed in many tissues, its expression in epidermal keratinocytes remains unclear. We investigated PEPT2 expression profile and functional activity in keratinocytes. We confirmed PEPT2 mRNA expression in three keratinocyte lines (normal human epidermal keratinocytes (NHEKs), immortalized keratinocytes, and malignant keratinocytes) by reverse transcription-polymerase chain reaction (RT-PCR) and quantitative real-time RT-PCR. In contrast to PEPT1, PEPT2 expression in the three keratinocytes was similar or higher than that in HepG2 cells, used as PEPT2-positive cells. Immunolocalization analysis using human skin showed epidermal PEPT2 localization. We studied keratinocyte transport function by measuring the oligopeptide content using liquid chromatography/tandem mass spectrometry. Glycylsarcosine uptake in NHEKs was pH-dependent, suggesting that keratinocytes could absorb small peptides in the presence of an inward H{sup +} gradient. We also performed a skin-permeability test of several oligopeptides using skin substitute, suggesting that di- and tripeptides pass actively through the epidermis. In conclusion, PEPT2 is expressed in keratinocytes and involved in skin oligopeptide uptake. -- Highlights: •PEPT2 is expressed in keratinocytes, which are more common than other skin cells. •Immunolocalization analysis using human skin revealed epidermal PEPT2 localization. •Keratinocytes could absorb small peptides in the presence of an inward H{sup +} gradient. •Di- and tripeptide pass actively through the epidermis.

Butyrate transcriptionally enhances peptide transporter PepT1 expression and activity.

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Guillaume Dalmasso

Full Text Available BACKGROUND: PepT1, an intestinal epithelial apical di/tripeptide transporter, is normally expressed in the small intestine and induced in colon during chronic inflammation. This study aimed at investigating PepT1 regulation by butyrate, a short-chain fatty acid produced by commensal bacteria and accumulated inside inflamed colonocyte. RESULTS: We found that butyrate treatment of human intestinal epithelial Caco2-BBE cells increased human PepT1 (hPepT1 promoter activity in a dose- and time-dependent manner, with maximal activity observed in cells treated with 5 mM butyrate for 24 h. Under this condition, hPepT1 promoter activity, mRNA and protein expression levels were increased as assessed by luciferase assay, real-time RT-PCR and Western blot, respectively. hPepT1 transport activity was accordingly increased by approximately 2.5-fold. Butyrate did not alter hPepT1 mRNA half-life indicating that butyrate acts at the transcriptional level. Molecular analyses revealed that Cdx2 is the most important transcription factor for butyrate-induced increase of hPepT1 expression and activity in Caco2-BBE cells. Butyrate-activated Cdx2 binding to hPepT1 promoter was confirmed by gel shift and chromatin immunoprecipitation. Moreover, Caco2-BBE cells overexpressing Cdx2 exhibited greater hPepT1 expression level than wild-type cells. Finally, treatment of mice with 5 mM butyrate added to drinking water for 24 h increased colonic PepT1 mRNA and protein expression levels, as well as enhanced PepT1 transport activity in colonic apical membranes vesicles. CONCLUSIONS: Collectively, our results demonstrate that butyrate increases PepT1 expression and activity in colonic epithelial cells, which provides a new understanding of PepT1 regulation during chronic inflammation.

Acyclovir prodrug for the intestinal di/tri-peptide transporter PEPT1

DEFF Research Database (Denmark)

Thomsen, Anne Engelbrecht; Christensen, Michael Søberg; Bagger, Morten Aavad

2004-01-01

It has previously been shown that the prodrug Glu(acyclovir)-Sar has a high affinity for PEPT1 in Caco-2 cells. However, affinity does not necessarily lead to translocation by the transporter which is necessary for achieving an increased oral bioavailability. Therefore i.v. and p.o. doses of Glu......(acyclovir)-Sar, acyclovir and valacyclovir were given to rats and the collected blood samples were analysed via LC-MS-MS. Furthermore, Caco-2 cell monolayers were exposed apically to Glu(acyclovir)-Sar, acyclovir, and valacyclovir and the concentration of drug and prodrugs in the cell extracts were determined and taken...... as a measure for intracellular accumulation. In addition, bi-directional transport studies of Glu(acyclovir)-Sar across Caco-2 cell monolayers and in vitro metabolism studies of Glu(acyclovir)-Sar in various media of rat origin were performed. For these purposes HPLC-UV analysis was applied. Oral...

Carrier-mediated γ-aminobutyric acid transport across the basolateral membrane of human intestinal Caco-2 cell monolayers.

Science.gov (United States)

Nielsen, Carsten Uhd; Carstensen, Mette; Brodin, Birger

2012-06-01

The aim of the present study was to investigate the transport of γ-aminobutyric acid (GABA) across the basolateral membrane of intestinal cells. The proton-coupled amino acid transporter, hPAT1, mediates the influx of GABA and GABA mimetic drug substances such as vigabatrin and gaboxadol and the anticancer prodrug δ-aminolevulinic acid across the apical membrane of small intestinal enterocytes. Little is however known about the basolateral transport of these substances. We investigated basolateral transport of GABA in mature Caco-2 cell monolayers using isotope studies. Here we report that, at least two transporters seem to be involved in the basolateral transport of GABA. The basolateral uptake consisted of a high-affinity system with a K(m) of 290 μM and V(max) of 75 pmol cm(-2) min(-1) and a low affinity system with a K(m) of approximately 64 mM and V(max) of 1.6 nmol cm(-2) min(-1). The high-affinity transporter is Na(+) and Cl(-) dependent. The substrate specificity of the high-affinity transporter was further studied and Gly-Sar, Leucine, gaboxadol, sarcosine, lysine, betaine, 5-hydroxythryptophan, proline and glycine reduced the GABA uptake to approximately 44-70% of the GABA uptake in the absence of inhibitor. Other substances such as β-alanine, GABA, 5-aminovaleric acid, taurine and δ-aminolevulinic acid reduced the basolateral GABA uptake to 6-25% of the uptake in the absence of inhibitor. Our results indicate that the distance between the charged amino- and acid-groups is particular important for inhibition of basolateral GABA uptake. Thus, there seems to be a partial substrate overlap between the basolateral GABA transporter and hPAT1, which may prove important for understanding drug interactions at the level of intestinal transport. Copyright © 2012 Elsevier B.V. All rights reserved.

Transepithelial transport of flavanone in intestinal Caco-2 cell monolayers

International Nuclear Information System (INIS)

Kobayashi, Shoko; Konishi, Yutaka

2008-01-01

Our recent study [S. Kobayashi, S. Tanabe, M. Sugiyama, Y. Konishi, Transepithelial transport of hesperetin and hesperidin in intestinal Caco-2 cell monolayers, Biochim. Biophys. Acta, 1778 (2008) 33-41] shows that the mechanism of absorption of hesperetin involves both proton-coupled active transport and transcellular passive diffusion. Here, as well as analyzing the cell permeability of hesperetin, we also study the transport of other flavanones, naringenin and eriodictyol, using Caco-2 cell monolayers. Similar to hesperetin mentioned, naringenin and eriodictyol showed proton-coupled polarized transport in apical-to-basolateral direction in non-saturable manner, constant permeation in the apical-to-basolateral direction (J ap→bl ) irrespective of the transepithelial electrical resistance (TER), and preferable distribution into the basolateral side after apical loading in the presence of a proton gradient. Furthermore, the proton-coupled J ap→bl of hesperetin, naringenin and eriodictyol, were inhibited by substrates of the monocarboxylic acid transporter (MCT), such as benzoic acid, but not by ferulic acid. In contrast, both benzoic and ferulic acids have no stimulatory effect on J ap→bl of each flavanone by trans-stimulation analysis. These results indicates that proton-driven active transport is commonly participated in the absorption of flavanone in general, and that its transport is presumed to be unique other than MCT-mediated transport for absorption of phenolic acids (PAs), sodium-dependent MCT (SMCT) nor anion exchanger-mediated transport

Evaluation of leader peptides that affect the secretory ability of a multiple bacteriocin transporter, EnkT.

Science.gov (United States)

Sushida, Hirotoshi; Ishibashi, Naoki; Zendo, Takeshi; Wilaipun, Pongtep; Leelawatcharamas, Vichien; Nakayama, Jiro; Sonomoto, Kenji

2018-02-13

EnkT is a novel ATP-binding cassette (ABC) transporter responsible for secretion of four bacteriocins, enterocins NKR-5-3A, C, D, and Z (Ent53A, C, D, and Z), produced by Enterococcus faecium NKR-5-3. It is generally recognized that the secretion of a bacteriocin requires a dedicated ABC transporter, although molecular mechanisms of this secretion are yet to be revealed. In order to characterize the unique ability of EnkT to secrete multiple bacteriocins, the role of N-terminal leader peptides of bacteriocin precursors was evaluated using Ent53C precursor as a model. The 18-amino acid leader peptide of Ent53C (Lc) was modified by site-directed mutagenesis to generate various point mutations, truncations, or extensions, and substitutions with other leader peptides. The impact of these Lc mutations on Ent53C secretion was evaluated using a quantitative antimicrobial activity assay. We observed that Ent53C production increased with Ala substitution of the highly conserved C-terminal double glycine residues that are recognized as the cleavage site. In contrast, Ent53C antimicrobial activity decreased, with decrease in the length of the putative α-helix-forming region of Lc. Furthermore, EnkT recognized and transported Ent53C of the transformants possessing heterologous leader peptides of enterocin A, pediocin PA-1, brochocins A and B, and lactococcins Qα and Qβ. These results indicated that EnkT shows significant tolerance towards the sequence and length of leader peptides, to secrete multiple bacteriocins. This further demonstrates the functional diversity of bacteriocin ABC transporters and the importance of leader peptides as their recognition motif. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Oral bioavailability assessment and intestinal lymphatic transport of Org 45697 and Org 46035, two highly lipophilic novel immunomodulator analogues.

Science.gov (United States)

Caliph, Suzanne M; Faassen, W A Fried; Vogel, Gerard M; Porter, Christopher J H

2009-08-01

Org 45697 (MW 600.7, clogP 7.92, soybean oil solubility 50 mg/g) and Org 46035 (MW 601.6, clog P 8.46, soybean oil solubility 40 mg/g) are two poorly water soluble ( 5 fold) after oral administration in a long chain triglyceride lipid (olive oil) formulation. Subsequent studies have explored the potential for solubilising formulations, including lipid-based formulations, to enhance the oral bioavailability of Org 45697 and Org 46035 and secondly to explore the potential contribution of intestinal lymphatic transport to intestinal absorption. The experimental data show that solubilising formulations may provide for significant increases in oral bioavailability for Org 45697 and Org 46035 and that after co-administration with lipid, 35-50% of the absorbed dose may be transported to the systemic circulation via the intestinal lymph. Interestingly, the lymphatic transport of the less lipid soluble analogue, Org 46035 was approximately 40% lower than that of Org 45697 suggesting that relatively subtle differences in lipid solubility can have significant impact on the extent of lymphatic transport.

New approaches to the treatments of short bowel syndrome-associated intestinal failure

DEFF Research Database (Denmark)

Jeppesen, Palle B

2014-01-01

PURPOSE OF REVIEW: Teduglutide, a recombinant analog of human glucagon-like peptide 2, has recently been approved in the US and Europe (Gattex and Revestive, respectively) as the first targeted treatment of short bowel syndrome-associated intestinal failure (SBS-IF). Glucagon-like peptide 2...... improves structural and functional intestinal adaptation following intestinal resection by decelerating a rapid gastric emptying, by decreasing gastric hypersecretion, by increasing intestinal blood flow and by promoting intestinal growth. This review summarizes the findings from phase 2 and 3 studies...... energy losses by approximately 0.8 MJ/day (∼200 kcal/day). In two subsequent 24-week, phase 3 studies, teduglutide reduced the need for parenteral support in the same magnitude. Teduglutide had an acceptable tolerability profile, where adverse events generally were of gastrointestinal origin consistent...

Dysbiosis of Intestinal Microbiota and Decreased Antimicrobial Peptide Level in Paneth Cells during Hypertriglyceridemia-Related Acute Necrotizing Pancreatitis in Rats

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Chunlan Huang

2017-05-01

Full Text Available Hypertriglyceridemia (HTG aggravates the course of acute pancreatitis (AP. Intestinal barrier dysfunction is implicated in the pathogenesis of AP during which dysbiosis of intestinal microbiota contributes to the dysfunction in intestinal barrier. However, few studies focus on the changes in intestine during HTG-related acute necrotizing pancreatitis (ANP. Here, we investigated the changes in intestinal microbiota and Paneth cell antimicrobial peptides (AMPs in HTG-related ANP (HANP in rats. Rats fed a high-fat diet to induce HTG and ANP was induced by retrograde injection of 3.5% sodium taurocholate into biliopancreatic duct. Rats were sacrificed at 24 and 48 h, respectively. Pancreatic and ileal injuries were evaluated by histological scores. Intestinal barrier function was assessed by plasma diamine oxidase activity and D-lactate level. Systemic and intestinal inflammation was evaluated by tumor necrosis factor alpha (TNFα, interleukin (IL-1β, and IL-17A expression. 16S rRNA high throughput sequencing was used to investigate changes in intestinal microbiota diversity and structure. AMPs (α-defensin5 and lysozyme expression was measured by real-time polymerase chain reaction (PCR and immunofluorescence. The results showed that compared with those of normal-lipid ANP (NANP groups, the HANP groups had more severe histopathological injuries in pancreas and distal ileum, aggravated intestinal barrier dysfunction and increased TNFα, IL-1β, and IL-17A expression in plasma and distal ileum. Principal component analysis showed structural segregation between the HANP and NANP group. α-Diversity estimators in the HANP group revealed decreased microbiota diversity compared with that in NANP group. Taxonomic analysis showed dysbiosis of intestinal microbiota structure. In the HANP group, at phyla level, Candidatus_Saccharibacteria and Tenericutes decreased significantly, whereas Actinobacteria increased. At genus level, Allobaculum, Bifidobacterium

Gene expression of transporters and phase I/II metabolic enzymes in murine small intestine during fasting

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van der Meijde Jolanda

2007-08-01

Full Text Available Abstract Background Fasting has dramatic effects on small intestinal transport function. However, little is known on expression of intestinal transport and phase I/II metabolism genes during fasting and the role the fatty acid-activated transcription factor PPARα may play herein. We therefore investigated the effects of fasting on expression of these genes using Affymetrix GeneChip MOE430A arrays and quantitative RT-PCR. Results After 24 hours of fasting, expression levels of 33 of the 253 analyzed transporter and phase I/II metabolism genes were changed. Upregulated genes were involved in transport of energy-yielding molecules in processes such as glycogenolysis (G6pt1 and mitochondrial and peroxisomal oxidation of fatty acids (Cact, Mrs3/4, Fatp2, Cyp4a10, Cyp4b1. Other induced genes were responsible for the inactivation of the neurotransmitter serotonin (Sert, Sult1d1, Dtd, Papst2, formation of eicosanoids (Cyp2j6, Cyp4a10, Cyp4b1, or for secretion of cholesterol (Abca1 and Abcg8. Cyp3a11, typically known because of its drug metabolizing capacity, was also increased. Fasting had no pronounced effect on expression of phase II metabolic enzymes, except for glutathione S-transferases which were down-regulated. Time course studies revealed that some genes were acutely regulated, whereas expression of other genes was only affected after prolonged fasting. Finally, we identified 8 genes that were PPARα-dependently upregulated upon fasting. Conclusion We have characterized the response to fasting on expression of transporters and phase I/II metabolic enzymes in murine small intestine. Differentially expressed genes are involved in a variety of processes, which functionally can be summarized as a increased oxidation of fat and xenobiotics, b increased cholesterol secretion, c increased susceptibility to electrophilic stressors, and d reduced intestinal motility. This knowledge increases our understanding of gut physiology, and may be of relevance

Vasoactive intestinal peptide (VIP) labelling with iodine-131 by direct method

International Nuclear Information System (INIS)

Colturato, M.T.; Silva, C.P.G. da; Araujo, E.B.

2002-01-01

The Vasoactive Intestinal Peptide (VIP) is a 28-amino acid polypeptide with a great numbers of receptors in tumoral cells, including adenocarcinomas and pancreatic and colon carcinomas. The VIP molecule contains two tyrosine residues, in positions 10 and 22, that are theoretically equally susceptible to iodination, The VIP was labeled with 131-iodine by direct method using Iodogen as oxidant agent: 15.03 mmol VIP + 0.10 nmol KI + [ 131 I]NaI + 13.9 mmol Iodogen; the final volume was adjust to 100 μL using 0.2 M phosphate buffer, pH 7.5 and the reaction proceed with stirring for 30 minutes at room temperature. The radiochemical purity was determined by electrophoresis (Whatman 1MM paper; 0.05 M barbital buffer; pH 8.6; 150 V; 40 minutes) that indicates low percent of free 131-iodine. The high performance liquid chromatography (HPLC) system using RPC 18 , 10 μm, 4 x 250mm column, was able to separate the different radiochemical species, only when an isocratic mixture of acetonitrile: 0.1% trifluoroacetic acid (27:73) was used, with 0.5 mL/min. flux. (author)

Pancreatic and intestinal processing of proglucagon in man

DEFF Research Database (Denmark)

Holst, J J; Poulsen, Steen Seier

1987-01-01

We developed antisera and radioimmunoassays against synthetic replicas of glucagon-like peptide-1 (1-36) and -2, predicted products of the glucagon precursor, and against glucagon-like peptide-1 (7-36) identical to the sequence of glucagon-like peptide-1, but lacking its first six N-terminal amino...... acids. With these tools, we studied the localisation and molecular nature of glucagon-like immunoreactivity in human pancreas, small intestine and plasma. By immunohistochemistry glucagon-like peptide-1, and glucagon-like peptide-2 immunoreactivity coexisted with glucagon in pancreatic islet cells...

The Contributions of Human Mini-Intestines to the Study of Intestinal Physiology and Pathophysiology.

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Yu, Huimin; Hasan, Nesrin M; In, Julie G; Estes, Mary K; Kovbasnjuk, Olga; Zachos, Nicholas C; Donowitz, Mark

2017-02-10

The lack of accessibility to normal and diseased human intestine and the inability to separate the different functional compartments of the intestine even when tissue could be obtained have held back the understanding of human intestinal physiology. Clevers and his associates identified intestinal stem cells and established conditions to grow "mini-intestines" ex vivo in differentiated and undifferentiated conditions. This pioneering work has made a new model of the human intestine available and has begun making contributions to the understanding of human intestinal transport in normal physiologic conditions and the pathophysiology of intestinal diseases. However, this model is reductionist and lacks many of the complexities of normal intestine. Consequently, it is not yet possible to predict how great the advances using this model will be for understanding human physiology and pathophysiology, nor how the model will be modified to include multiple other intestinal cell types and physical forces necessary to more closely approximate normal intestine. This review describes recent studies using mini-intestines, which have readdressed previously established models of normal intestinal transport physiology and newly examined intestinal pathophysiology. The emphasis is on studies with human enteroids grown either as three-dimensional spheroids or two-dimensional monolayers. In addition, comments are provided on mouse studies in cases when human studies have not yet been described.

Transport of nattokinase across the rat intestinal tract.

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Fujita, M; Hong, K; Ito, Y; Misawa, S; Takeuchi, N; Kariya, K; Nishimuro, S

1995-09-01

Intraduodenal administration of nattokinase (NK) at a dose of 80 mg/kg, resulted in the degradation of fibrinogen in plasma suggesting transport of NK across the intestinal tract in normal rats. The action of NK on the cleavage of fibrinogen in the plasma from blood samples drawn at intervals after intraduodenal administration of the enzyme was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting analysis with an anti-fibrinogen gamma chain antibody. The 270 kDa fragment carrying antigenic sites for the binding of the anti-fibrinogen gamma chain antibody appeared within 0.5 h and was then degraded gradually to a 105 kDa fragment via a 200 kDa fragment. This suggests that fibrinogen was degraded to a 105 kDa fragment via several intermediates (270 and 200 kDa). In parallel with the degradation process, plasma recalcification times were remarkably prolonged NK was also detected in the plasma from blood samples drawn 3 and 5 h after administration of the enzyme by SDS-PAGE and Western blotting analysis with an anti-NK antibody. The results indicate that NK is absorbed from the rat intestinal tract and that NK cleaves fibrinogen in plasma after intraduodenal administration of the enzyme.

Segmental dependent transport of low permeability compounds along the small intestine due to P-glycoprotein: the role of efflux transport in the oral absorption of BCS class III drugs.

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Dahan, Arik; Amidon, Gordon L

2009-01-01

The purpose of this study was to investigate the role of P-gp efflux in the in vivo intestinal absorption process of BCS class III P-gp substrates, i.e. high-solubility low-permeability drugs. The in vivo permeability of two H (2)-antagonists, cimetidine and famotidine, was determined by the single-pass intestinal perfusion model in different regions of the rat small intestine, in the presence or absence of the P-gp inhibitor verapamil. The apical to basolateral (AP-BL) and the BL-AP transport of the compounds in the presence or absence of various efflux transporters inhibitors (verapamil, erythromycin, quinidine, MK-571 and fumitremorgin C) was investigated across Caco-2 cell monolayers. P-gp expression levels in the different intestinal segments were confirmed by immunoblotting. Cimetidine and famotidine exhibited segmental dependent permeability through the gut wall, with decreased P(eff) in the distal ileum in comparison to the proximal regions of the intestine. Coperfusion of verapamil with the drugs significantly increased the permeability in the ileum, while no significant change in the jejunal permeability was observed. Both drugs exhibited significantly greater BL-AP than AP-BL Caco-2 permeability, indicative of net mucosal secretion. Concentration dependent decrease of this secretion was obtained by the P-gp inhibitors verapamil, erythromycin and quinidine, while no effect was evident by the MRP2 inhibitor MK-571 and the BCRP inhibitor FTC, indicating that P-gp is the transporter mediates the intestinal efflux of cimetidine and famotidine. P-gp levels throughout the intestine were inversely related to the in vivo permeability of the drugs from the different segments. The data demonstrate that for these high-solubility low-permeability P-gp substrates, P-gp limits in vivo intestinal absorption in the distal segments of the small intestine; however P-gp plays a minimal role in the proximal intestinal segments due to significant lower P-gp expression levels

Effects of vasoactive intestinal peptide on vascular conductance are unaffected by anesthesia

International Nuclear Information System (INIS)

Bouder, T.G.; Huffman, L.J.; Hedge, G.A.

1988-01-01

In rats anesthetized with ketamine and pentobarbital (KET/PB), vasoactive intestinal peptide (VIP) increases vascular conductance (VC) in the salivary gland, pancreas, and thyroid gland, whereas no changes in VC are observed in a number of other organs. Because anesthesia may alter the responsiveness of physiological systems, we compared the effects of VIP on organ VC in conscious or anesthetized rats. Chronically catheterized rats were studied in the conscious state or 30 min after induction of anesthesia with KET/PB, isoflurane, or Inactin. Blood flows were measured by the reference sample version of the radioactive microsphere (MS) technique using two MS injections ( 141 Ce-MS/ 85 Sr-MS). Mean arterial blood pressure was monitored and used in the calculation of VC. Organ VCs were similar under basal conditions in conscious and anesthetized rats. VIP infusion caused systemic hypotension and increased VCs in the salivary gland, pancreas, and thyroid gland, and these responses were largely unaffected by anesthesia. These results indicate that the anesthetics used do not alter basal VC or the responsiveness of the vasculature to exogenous VIP

Epidermal Growth Factor and Intestinal Barrier Function

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Xiaopeng Tang

2016-01-01

Full Text Available Epidermal growth factor (EGF is a 53-amino acid peptide that plays an important role in regulating cell growth, survival, migration, apoptosis, proliferation, and differentiation. In addition, EGF has been established to be an effective intestinal regulator helping to protect intestinal barrier integrity, which was essential for the absorption of nutrients and health in humans and animals. Several researches have demonstrated that EGF via binding to the EGF receptor and subsequent activation of Ras/MAPK, PI3K/AKT, PLC-γ/PKC, and STATS signal pathways regulates intestinal barrier function. In this review, the relationship between epidermal growth factor and intestinal development and intestinal barrier is described, to provide a better understanding of the effects of EGF on intestine development and health.

Does liver-intestine significantly degrade circulating endogenous substance P in man?

DEFF Research Database (Denmark)

Henriksen, Jens Henrik Sahl; Schaffalitzky de Muckadell, O B; Bülow, J B

1986-01-01

Elevated concentrations of circulating substance P in patients with liver insufficiency have been ascribed to decreased hepatic degradation. To establish a possible biodegradation of the peptide in liver-intestine and kidneys, the concentration of endogenous immunoreactive substance P was determi......Elevated concentrations of circulating substance P in patients with liver insufficiency have been ascribed to decreased hepatic degradation. To establish a possible biodegradation of the peptide in liver-intestine and kidneys, the concentration of endogenous immunoreactive substance P....... The results indicate that degradation of circulating endogenous substance P in man is not confined to liver-intestine or kidney but may take place in many tissues....

Protective effect of S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721) on irradiation-induced inhibition of intestinal transport function

International Nuclear Information System (INIS)

Chen, T.S.; Ando, M.

1983-01-01

The purpose of this study was to investigate the protective effect of S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721) on whole-body irradiation-induced inhibition of intestinal transport function. The jejunal transport of fluid and sugars was studied in male Swiss-Webster mice before and 3 days after whole-body irradiation (1000 rads). The rates of glucose and water transport were decreased by 86 and 70%, respectively, in irradiated animals. However, the rate of transport of 3-O-methyl-D-glucose (3MG) was not affected. In mice receiving WR-2721 (500 mg/kg, ip) 15 to 30 min prior to whole-body irradiation, net water flux was unaffected and the rate of D-glucose transport was decreased only 8%. WR-2721 administered alone (500 mg/kg, ip) had no effect on either D-glucose transport or net water flux across the jejunal mucosa. The results suggest that WR-2721 protects against irradiation-induced inhibition of some intestinal transport functions

Quantification of peptides released during in vitro digestion of cooked meat.

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Sayd, T; Chambon, C; Santé-Lhoutellier, V

2016-04-15

We aimed to identify and quantify the peptides generated during in vitro digestion of cooked meat by liquid chromatography coupled with high resolution mass spectrometer. A total of 940 non-redundant peptides in the gastric compartment and 989 non-redundant peptides in the intestinal compartment were quantified and identified. Among the 71 different proteins identified, 43 meat proteins were found in the two digestive compartments, 20 proteins were specific to the gastric compartment and 8 proteins to the intestinal compartment. In terms of estimation, the proteins involved in muscle contraction and structure were preferentially enzymatically hydrolyzed in the small intestine. The effect of cooking provided different but less clear patterns of digestion. To the best of our knowledge, this constitutes the highest number of peptides identified in beef meat digests and provides a comprehensive database for meat protein digestion associated with cooking conditions. Such quantitative and qualitative differences may have important nutritional consequences. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transintestinal transport of the anti-inflammatory drug 4F and the modulation of transintestinal cholesterol efflux[S

Science.gov (United States)

Meriwether, David; Sulaiman, Dawoud; Wagner, Alan; Grijalva, Victor; Kaji, Izumi; Williams, Kevin J.; Yu, Liqing; Fogelman, Spencer; Volpe, Carmen; Bensinger, Steven J.; Anantharamaiah, G. M.; Shechter, Ishaiahu; Fogelman, Alan M.; Reddy, Srinivasa T.

2016-01-01

The site and mechanism of action of the apoA-I mimetic peptide 4F are incompletely understood. Transintestinal cholesterol efflux (TICE) is a process involved in the clearance of excess cholesterol from the body. While TICE is responsible for at least 30% of the clearance of neutral sterols from the circulation into the intestinal lumen, few pharmacological agents have been identified that modulate this pathway. We show first that circulating 4F selectively targets the small intestine (SI) and that it is predominantly transported into the intestinal lumen. This transport of 4F into the SI lumen is transintestinal in nature, and it is modulated by TICE. We also show that circulating 4F increases reverse cholesterol transport from macrophages and cholesterol efflux from lipoproteins via the TICE pathway. We identify the cause of this modulation of TICE either as 4F being a cholesterol acceptor with respect to enterocytes, from which 4F enhances cholesterol efflux, or as 4F being an intestinal chaperone with respect to TICE. Our results assign a novel role for 4F as a modulator of the TICE pathway and suggest that the anti-inflammatory functions of 4F may be a partial consequence of the codependent intestinal transport of both 4F and cholesterol. PMID:27199144

Cell-Penetrating Peptides as Carriers for Oral Delivery of Biopharmaceuticals

DEFF Research Database (Denmark)

Kristensen, Mie; Nielsen, Hanne Mørck

2016-01-01

Oral delivery of biopharmaceuticals, for example peptides and proteins, constitutes a great challenge in drug delivery due to their low chemical stability and poor permeation across the intestinal mucosa, to a large extent limiting the mode of administration to injections, which is not favouring...... patient compliance. Nevertheless, cell-penetrating peptides (CPPs) have shown promising potential as carriers to overcome the epithelium, and this minireview highlights recent knowledge gained within the field of CPP-mediated transepithelial delivery of therapeutic peptides and proteins from the intestine...... is to be preferred depends on the physicochemical properties of both the specific CPP and the specific cargo. In addition to the physical epithelial barrier, a metabolic barrier must be overcome in order to obtain CPP-mediated delivery of a cargo drug from the intestine, and a number of strategies have been employed...

Watery diarrhea syndrome in an adult with ganglioneuroma-pheochromocytoma: identification of vasoactive intestinal peptide, calcitonin, and catecholamines and assessment of their biologic activity.

Science.gov (United States)

Trump, D L; Livingston, J N; Baylin, S B

1977-10-01

A case of adult ganglioneuroma-pheochromocytoma with an associated watery diarrhea syndrome is reported. High levels of vasoactive intestinal peptide (VIP) were found in preoperative serum and in tumor tissue. The serum VIP levels fell to normal, and the watery diarrhae syndrome completely ceased following removal of the tumor. In addition to containing VIP, the tumor was rich in catecholamines, and calcitonin. Peptide hormone-containing extracts and catecholamine extracts from the tumor both activated the adenyl cyclase system and increased lipolytic activity in a preparation of isolated rat fat cells. The findings in this patient further link VIP with neural crest tissues, and suggest the importance of determining catecholamine levels in patients with the watery diarrhea syndrome.

Dendrimer D5 is a vector for peptide transport to brain cells.

Science.gov (United States)

Sarantseva, S V; Bolshakova, O I; Timoshenko, S I; Kolobov, A A; Schwarzman, A L

2011-02-01

Dendrimers are a new class of nonviral vectors for gene or drug transport. Dendrimer capacity to penetrate through the blood-brain barrier remaines little studied. Biotinylated polylysine dendrimer D5, similarly to human growth hormone biotinylated fragment covalently bound to D5 dendrimer, penetrates through the blood-brain barrier and accumulates in Drosophila brain after injection into the abdomen. Hence, D5 dendrimer can serve as a vector for peptide transport to brain cells.

Excessive fructose intake causes 1,25-(OH)2D3-dependent inhibition of intestinal and renal calcium transport in growing rats

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Douard, Veronique; Sabbagh, Yves; Lee, Jacklyn; Patel, Chirag; Kemp, Francis W.; Bogden, John D.; Lin, Sheldon

2013-01-01

We recently discovered that chronic high fructose intake by lactating rats prevented adaptive increases in rates of active intestinal Ca2+ transport and in levels of 1,25-(OH)2D3, the active form of vitamin D. Since sufficient Ca2+ absorption is essential for skeletal growth, our discovery may explain findings that excessive consumption of sweeteners compromises bone integrity in children. We tested the hypothesis that 1,25-(OH)2D3 mediates the inhibitory effect of excessive fructose intake on active Ca2+ transport. First, compared with those fed glucose or starch, growing rats fed fructose for 4 wk had a marked reduction in intestinal Ca2+ transport rate as well as in expression of intestinal and renal Ca2+ transporters that was tightly associated with decreases in circulating levels of 1,25-(OH)2D3, bone length, and total bone ash weight but not with serum parathyroid hormone (PTH). Dietary fructose increased the expression of 24-hydroxylase (CYP24A1) and decreased that of 1α-hydroxylase (CYP27B1), suggesting that fructose might enhance the renal catabolism and impair the synthesis, respectively, of 1,25-(OH)2D3. Serum FGF23, which is secreted by osteocytes and inhibits CYP27B1 expression, was upregulated, suggesting a potential role of bone in mediating the fructose effects on 1,25-(OH)2D3 synthesis. Second, 1,25-(OH)2D3 treatment rescued the fructose effect and normalized intestinal and renal Ca2+ transporter expression. The mechanism underlying the deleterious effect of excessive fructose intake on intestinal and renal Ca2+ transporters is a reduction in serum levels of 1,25-(OH)2D3. This finding is significant because of the large amounts of fructose now consumed by Americans increasingly vulnerable to Ca2+ and vitamin D deficiency. PMID:23571713

Circulating levels of vasoactive peptides in patients with acute bacterial meningitis

DEFF Research Database (Denmark)

Berg, Ronan M G; Strauss, Gitte Irene; Tofteng, Flemming

2009-01-01

PURPOSE: The underlying mechanisms for cerebral blood flow (CBF) abnormalities in acute bacterial meningitis (ABM) are largely unknown. Putative mediators include vasoactive peptides, e.g. calcitonin-gene related peptide (CGRP), vasoactive intestinal peptide (VIP), and endothelin-1 (ET-1), all...

Limitations to the use of radioactively labelled substrates for studying peptide transport in microorganisms

International Nuclear Information System (INIS)

Payne, J.W.; Nisbet, T.M.

1980-01-01

The authors wished to investigate the stoicheiometry of energy coupling to peptide transport in whole cells of several organisms, a study that requires accurate measurements of the rate and amount of peptide translocation. They show that using radioactively-labelled substrates can lead to severe miscalculation of these parameters and produce misleading data on the kinetics of uptake. These conclusions are based on comparative studies using the fluorescamine and dansyl procedures. (Auth.)

Aquaporin expression in the Japanese medaka (Oryzias latipes) in freshwater and seawater: challenging the paradigm of intestinal water transport?

DEFF Research Database (Denmark)

Madsen, Steffen; Bujak, Joanna; Tipsmark, Christian

2014-01-01

response to salinity, suggesting that water transport is not regulated at this level. In contrast, mRNA of the Na+,K+,2Cl–-cotransporter type-2 strongly increased in the intestine in SW compared with FW fish. Using custom-made antibodies, Aqp1a, Aqp8ab and Aqp10a were localized in the apical region...... in the intestine of SW fish is surprising, and challenges the paradigm for transepithelial intestinal water absorption in SW fishes....

A Macrocyclic Peptide that Serves as a Cocrystallization Ligand and Inhibits the Function of a MATE Family Transporter

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Hiroaki Suga

2013-08-01

Full Text Available The random non-standard peptide integrated discovery (RaPID system has proven to be a powerful approach to discover de novo natural product-like macrocyclic peptides that inhibit protein functions. We have recently reported three macrocyclic peptides that bind to Pyrococcus furiosus multidrug and toxic compound extrusion (PfMATE transporter and inhibit the transport function. Moreover, these macrocyclic peptides were successfully employed as cocrystallization ligands of selenomethionine-labeled PfMATE. In this report, we disclose the details of the RaPID selection strategy that led to the identification of these three macrocyclic peptides as well as a fourth macrocyclic peptide, MaD8, which is exclusively discussed in this article. MaD8 was found to bind within the cleft of PfMATE’s extracellular side and blocked the path of organic small molecules being extruded. The results of an ethidium bromide efflux assay confirmed the efflux inhibitory activity of MaD8, whose behavior was similar to that of previously reported MaD5.

Chicken antimicrobial peptides: biological functions and possible applications

NARCIS (Netherlands)

Dijk, Albert van

2007-01-01

Farm animals often suffer from diseases of the gastro-intestinal tract. Modulation of natural defence mechanisms by dietary additives may be one way to improve intestinal health and food safety. In mammals, antimicrobial peptides (AMPs) play an important role in the host defence of skin and mucosal

High Levels of Dietary Supplement Vitamins A, C and E are Absorbed in the Small Intestine and Protect Nutrient Transport Against Chronic Gamma Irradiation

Science.gov (United States)

Azzam, Edouard I.; Ferraris, Ronaldo P.; Howell, Roger W.

2015-01-01

We examined nutrient transport in the intestines of mice exposed to chronic low-LET 137Cs gamma rays. The mice were whole-body irradiated for 3 days at dose rates of 0, 0.13 and 0.20 Gy/h, for total dose delivery of 0, 9.6 or 14.4 Gy, respectively. The mice were fed either a control diet or a diet supplemented with high levels of vitamins A, C and E. Our results showed that nutrient transport was perturbed by the chronic irradiation conditions. However, no apparent alteration of the macroscopic intestinal structures of the small intestine were observed up to day 10 after initiating irradiation. Jejunal fructose uptake measured in vitro was strongly affected by the chronic irradiation, whereas uptake of proline, carnosine and the bile acid taurocholate in the ileum was less affected. D-glucose transport did not appear to be inhibited significantly by either 9.6 or 14.4 Gy exposure. In the 14.4 Gy irradiated groups, the diet supplemented with high levels of vitamins A, C and E increased intestinal transport of fructose compared to the control diet (day 10; t test, P = 0.032), which correlated with elevated levels of vitamins A, C and E in the plasma and jejunal enterocytes. Our earlier studies with mice exposed acutely to 137Cs gamma rays demonstrated significant protection for transport of fructose, glucose, proline and carnosine. Taken together, these results suggest that high levels of vitamins A, C and E dietary supplements help preserve intestinal nutrient transport when intestines are irradiated chronically or acutely with low-LET gamma rays. PMID:26484399

Unusual chemical properties of N-terminal histidine residues of glucagon and vasoactive intestinal peptide

International Nuclear Information System (INIS)

Hefford, M.A.; Evans, R.M.; Oda, G.; Kaplan, H.

1985-01-01

An N-terminal histidine residue of a protein or peptide has two functional groups, viz., an alpha-amino group and an imidazole group. A new procedure, based on the competitive labeling approach described by Duggleby and Kaplan has been developed by which the chemical reactivity of each functional group in such a residue can be determined as a function of pH. Only very small amounts of material are required, which makes it possible to determine the chemical properties in dilute solution or in proteins and polypeptides that can be obtained in only minute quantities. With this approach, the reactivity of the alpha-amino group of histidylglycine toward 1-fluoro-2,4-dinitrobenzene gave an apparent pK /sub a/ value of 7.64 +/- 0.07 at 37 degrees C, in good agreement with a value of 7.69 +/- 0.02 obtained by acid-base titration. However, the reactivity of the imidazole function gave an apparent pK /sub a/ value of 7.16 +/- 0.07 as compared to the pK /sub a/ value of 5.85 +/- 0.01 obtained by acid-base titration. Similarly, in glucagon and vasoactive intestinal peptide (VIP), apparent pKa values of 7.60 +/- 0.04 and 7.88 +/- 0.18, respectively, were obtained for the alpha-amino of their N-terminal histidine, and pKa values of 7.43 +/- 0.09 and 7.59 +/- 0.18 were obtained for the imidazole function

Precision-cut intestinal slices: alternative model for drug transport, metabolism, and toxicology research.

Science.gov (United States)

Li, Ming; de Graaf, Inge A M; Groothuis, Geny M M

2016-01-01

The absorption, distribution, metabolism, excretion and toxicity (ADME-tox) processes of drugs are of importance and require preclinical investigation intestine in addition to the liver. Various models have been developed for prediction of ADME-tox in the intestine. In this review, precision-cut intestinal slices (PCIS) are discussed and highlighted as model for ADME-tox studies. This review provides an overview of the applications and an update of the most recent research on PCIS as an ex vivo model to study the transport, metabolism and toxicology of drugs and other xenobiotics. The unique features of PCIS and the differences with other models as well as the translational aspects are also discussed. PCIS are a simple, fast, and reliable ex vivo model for drug ADME-tox research. Therefore, PCIS are expected to become an indispensable link in the in vitro-ex vivo-in vivo extrapolation, and a bridge in translation of animal data to the human situation. In the future, this model may be helpful to study the effects of interorgan interactions, intestinal bacteria, excipients and drug formulations on the ADME-tox properties of drugs. The optimization of culture medium and the development of a (cryo)preservation technique require more research.

Protective Effect of Wheat Peptides against Indomethacin-Induced Oxidative Stress in IEC-6 Cells

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Hong Yin

2014-01-01

Full Text Available Recent studies have demonstrated that wheat peptides protected rats against non-steroidal anti-inflammatory drugs-induced small intestinal epithelial cells damage, but the mechanism of action is unclear. In the present study, an indomethacin-induced oxidative stress model was used to investigate the effect of wheat peptides on the nuclear factor-κB(NF-κB-inducible nitric oxide synthase-nitric oxide signal pathway in intestinal epithelial cells-6 cells. IEC-6 cells were treated with wheat peptides (0, 125, 500 and 2000 mg/L for 24 h, followed by 90 mg/L indomethacin for 12 h. Wheat peptides significantly attenuated the indomethacin-induced decrease in superoxide dismutase and glutathione peroxidase activity. Wheat peptides at 2000 mg/L markedly decreased the expression of the NF-κB in response to indomethacin-induced oxidative stress. This study demonstrated that the addition of wheat peptides to a culture medium significantly inhibited the indomethacin-induced release of malondialdehyde and nitrogen monoxide, and increased antioxidant enzyme activity in IEC-6 cells, thereby providing a possible explanation for the protective effect proposed for wheat peptides in the prevention of indomethacin-induced oxidative stress in small intestinal epithelial cells.

Defying the stereotype: non-canonical roles of the peptide hormones guanylin and uroguanylin

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Nirmalya eBasu

2011-06-01

Full Text Available The peptide hormones uroguanylin and guanylin have been traditionally thought to be mediators of fluid-ion homeostasis in the vertebrate intestine. They serve as ligands for receptor guanylyl cyclase C (GC-C, and both receptor and ligands are expressed predominantly in the intestine. Ligand binding to GC-C results in increased cGMP production in the cell which governs downstream signaling. In the last decade, a significant amount of research has unraveled novel functions for this class of peptide hormones, in addition to their action as intestinal secretagogues. An additional receptor for uroguanylin, receptor guanylyl cyclase D, has also been identified. Thus, unconventional roles of these peptides in regulating renal filtration, olfaction, reproduction and cell proliferation have begun to be elucidated in detail. These varied effects suggest that these peptide hormones act in an autocrine, paracrine as well as endocrine manner to regulate diverse cellular processes.

Lack of effects of a single high-fat meal enriched with vegetable n-3 or a combination of vegetable and marine n-3 fatty acids on intestinal peptide release and adipokines in healthy female subjects

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Ingunn Naverud

2016-08-01

Full Text Available Peptides released from the small intestine and colon regulate short-term food intake by suppressing appetite and inducing satiety. Intake of marine omega-3 (n-3 fatty acids from fish and fish oils is associated with beneficial health effects, whereas the relation between intake of the vegetable n-3 fatty acid α-linolenic acid and diseases is less clear. The aim of the present study was to investigate the postprandial effects of a single high-fat meal enriched with vegetable n-3 or a combination of vegetable and marine n-3 fatty acids with their different unsaturated fatty acid composition on intestinal peptide release and the adipose tissue. Fourteen healthy lean females consumed three test meals with different fat quality in a fixed order. The test meal consisted of three cakes enriched with coconut fat, linseed oil and a combination of linseed and cod liver oil. The test days were separated by two weeks. Fasting and postprandial blood samples at three and six hours after intake were analysed. A significant postprandial effect was observed for cholecystokinin, peptide YY, glucose-dependent insulinotropic polypeptide, amylin and insulin which increased, while leptin decreased postprandially independent of the fat composition in the high-fat meal. In conclusion, in healthy, young, lean females, an intake of a high-fat meal enriched with n-3 fatty acids from different origin stimulates intestinal peptide release without any difference between the different fat compositions.

Targeting nanoparticles to M cells with non-peptidic ligands for oral vaccination.

Science.gov (United States)

Fievez, Virginie; Plapied, Laurence; des Rieux, Anne; Pourcelle, Vincent; Freichels, Hélène; Wascotte, Valentine; Vanderhaeghen, Marie-Lyse; Jerôme, Christine; Vanderplasschen, Alain; Marchand-Brynaert, Jacqueline; Schneider, Yves-Jacques; Préat, Véronique

2009-09-01

The presence of RGD on nanoparticles allows the targeting of beta1 integrins at the apical surface of human M cells and the enhancement of an immune response after oral immunization. To check the hypothesis that non-peptidic ligands targeting intestinal M cells or APCs would be more efficient for oral immunization than RGD, novel non-peptidic and peptidic analogs (RGD peptidomimitic (RGDp), LDV derivative (LDVd) and LDV peptidomimetic (LDVp)) as well as mannose were grafted on the PEG chain of PCL-PEG and incorporated in PLGA-based nanoparticles. RGD and RGDp significantly increased the transport of nanoparticles across an in vitro model of human M cells as compared to enterocytes. RGD, LDVp, LDVd and mannose enhanced nanoparticle uptake by macrophages in vitro. The intraduodenal immunization with RGDp-, LDVd- or mannose-labeled nanoparticles elicited a higher production of IgG antibodies than the intramuscular injection of free ovalbumin or intraduodenal administration of either non-targeted or RGD-nanoparticles. Targeted formulations were also able to induce a cellular immune response. In conclusion, the in vitro transport of nanoparticles, uptake by macrophages and the immune response were positively influenced by the presence of ligands at the surface of nanoparticles. These targeted-nanoparticles could thus represent a promising delivery system for oral immunization.

L-Theanine Administration Modulates the Absorption of Dietary Nutrients and Expression of Transporters and Receptors in the Intestinal Mucosa of Rats

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Qiongxian Yan

2017-01-01

Full Text Available L-theanine has various advantageous functions for human health; whether or not it could mediate the nutrients absorption is unknown yet. The effects of L-theanine on intestinal nutrients absorption were investigated using rats ingesting L-theanine solution (0, 50, 200, and 400 mg/kg body weight per day for two weeks. The decline of insulin secretion and glucose concentration in the serum was observed by L-theanine. Urea and high-density lipoprotein were also reduced by 50 mg/kg L-theanine. Jejunal and ileac basic amino acids transporters SLC7a1 and SLC7a9, neutral SLC1a5 and SLC16a10, and acidic SLC1a1 expression were upregulated. The expression of intestinal SGLT3 and GLUT5 responsible for carbohydrates uptake and GPR120 and FABP2 associated with fatty acids transport were inhibited. These results indicated that L-theanine could inhibit the glucose uptake by downregulating the related gene expression in the small intestine of rats. Intestinal gene expression of transporters responding to amino acids absorption was stimulated by L-theanine administration.

Functional nanoparticles exploit the bile acid pathway to overcome multiple barriers of the intestinal epithelium for oral insulin delivery

DEFF Research Database (Denmark)

Fan, Weiwei; Xia, Dengning; Zhu, Quanlei

2018-01-01

, especially to avoid lysosomal degradation, and basolateral release. Here, the functional material, deoxycholic acid-conjugated chitosan, is synthesized and loaded with the model protein drug insulin into deoxycholic acid-modified nanoparticles (DNPs). The DNPs designed in this study are demonstrated......Oral absorption of protein/peptide-loaded nanoparticles is often limited by multiple barriers of the intestinal epithelium. In addition to mucus translocation and apical endocytosis, highly efficient transepithelial absorption of nanoparticles requires successful intracellular trafficking...... to endolysosomal escape of DNPs. Additionally, DNPs can interact with a cytosolic ileal bile acid-binding protein that facilitates the intracellular trafficking and basolateral release of insulin. In rats, intravital two-photon microscopy also reveals that the transport of DNPs into the intestinal villi...

Specificity of the second binding protein of the peptide ABC-transporter (Dpp) of Lactococcus lactis IL1403

NARCIS (Netherlands)

Sanz, Y; Toldra, F; Renault, P; Poolman, B

2003-01-01

The genome sequence of Lactococcus lactis IL1403 revealed the presence of a putative peptide-binding protein-dependent ABC-transporter (Dpp). The genes for two peptide-binding proteins (dppA and dppP) precede the membrane components, which include two transmembrane protein genes (dppB and dppC) and

Regulation of transepithelial transport of iron by hepcidin

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NATALIA P MENA

2006-01-01

Full Text Available Hepcidin (Hepc is a 25 amino acid cationic peptide with broad antibacterial and antifungal actions. A likely role for Hepc in iron metabolism was suggested by the observation that mice having disruption of the gene encoding the transcription factor USF2 failed to produce Hepc mRNA and developed spontaneous visceral iron overload. Lately, Hepc has been considered the "stores regulator," a putative factor that signals the iron content of the body to intestinal cells. In this work, we characterized the effect of Hepc produced by hepatoma cells on iron absorption by intestinal cells. To that end, human Hepc cDNA was cloned and overexpressed in HepG2 cells and conditioned media from Hepc-overexpressing cells was used to study the effects of Hepc on intestinal Caco-2 cells grown in bicameral inserts. The results indicate that Hepc released by HepG2 inhibited apical iron uptake by Caco-2 cells, probably by inhibiting the expression of the apical transporter DMT1. These results support a model in which Hepc released by the liver negatively regulates the expression of transporter DMT1 in the enterocyte

Alternative Functional In Vitro Models of Human Intestinal Epithelia

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Amanda L Kauffman

2013-07-01

Full Text Available Physiologically relevant sources of absorptive intestinal epithelial cells are crucial for human drug transport studies. Human adenocarcinoma-derived intestinal cell lines, such as Caco-2, offer conveniences of easy culture maintenance and scalability, but do not fully recapitulate in vivo intestinal phenotypes. Additional sources of renewable physiologically relevant human intestinal cells would provide a much needed tool for drug discovery and intestinal physiology. We sought to evaluate and compare two alternative sources of human intestinal cells, commercially available primary human intestinal epithelial cells (hInEpCs and induced pluripotent stem cell (iPSC-derived intestinal cells to Caco-2, for use in in vitro transwell monolayer intestinal transport assays. To achieve this for iPSC-derived cells, our previously described 3-dimensional intestinal organogenesis method was adapted to transwell differentiation. Intestinal cells were assessed by marker expression through immunocytochemical and mRNA expression analyses, monolayer integrity through Transepithelial Electrical Resistance (TEER measurements and molecule permeability, and functionality by taking advantage the well-characterized intestinal transport mechanisms. In most cases, marker expression for primary hInEpCs and iPSC-derived cells appeared to be as good as or better than Caco-2. Furthermore, transwell monolayers exhibited high TEER with low permeability. Primary hInEpCs showed molecule efflux indicative of P-glycoprotein transport. Primary hInEpCs and iPSC-derived cells also showed neonatal Fc receptor-dependent binding of immunoglobulin G variants. Primary hInEpCs and iPSC-derived intestinal cells exhibit expected marker expression and demonstrate basic functional monolayer formation, similar to or better than Caco-2. These cells could offer an alternative source of human intestinal cells for understanding normal intestinal epithelial physiology and drug transport.

Structure of protein emulsion in food impacts intestinal microbiota, caecal luminal content composition and distal intestine characteristics in rats.

Science.gov (United States)

Beaumont, Martin; Jaoui, Daphné; Douard, Véronique; Mat, Damien; Koeth, Fanny; Goustard, Bénédicte; Mayeur, Camille; Mondot, Stanislas; Hovaghimian, Anais; Le Feunteun, Steven; Chaumontet, Catherine; Davila, Anne-Marie; Tomé, Daniel; Souchon, Isabelle; Michon, Camille; Fromentin, Gilles; Blachier, François; Leclerc, Marion

2017-10-01

Few studies have evaluated in vivo the impact of food structure on digestion, absorption of nutrients and on microbiota composition and metabolism. In this study we evaluated in rat the impact of two structures of protein emulsion in food on gut microbiota, luminal content composition, and intestinal characteristics. Rats received for 3 weeks two diets of identical composition but based on lipid-protein matrices of liquid fine (LFE) or gelled coarse (GCE) emulsion. LFE diet led to higher abundance, when compared to the GCE, of Lactobacillaceae (Lactobacillus reuteri) in the ileum, higher β-diversity of the caecum mucus-associated bacteria. In contrast, the LFE diet led to a decrease in Akkermansia municiphila in the caecum. This coincided with heavier caecum content and higher amount of isovalerate in the LFE group. LFE diet induced an increased expression of (i) amino acid transporters in the ileum (ii) glucagon in the caecum, together with an elevated level of GLP-1 in portal plasma. However, these intestinal effects were not associated with modification of food intake or body weight gain. Overall, the structure of protein emulsion in food affects the expression of amino acid transporters and gut peptides concomitantly with modification of the gut microbiota composition and activity. Our data suggest that these effects of the emulsion structure are the result of a modification of protein digestion properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The mRNA expression of amino acid and sugar transporters, aminopeptidase, as well as the di- and tri-peptide transporter PepT1 in the intestines of Eimeria infected broiler chickens.

Science.gov (United States)

Miska, K B; Fetterer, R H

2017-02-01

Coccidiosis in chickens is caused by infection of gut epithelial cells with protozoan parasites of the genus Eimeria This disease causes losses to the poultry industry since infected birds fail to gain weight as rapidly as non-infected birds and efficiency of feed conversion is compromised. For the present study the effect of Eimeria on expression of components of amino acid and sugar uptake mechanisms was determined. Broiler chicks were infected with Eimeria maxima, which infects the jejunum; Eimeria acervulina, which infects the duodenum; or Eimeria tenella, which infects the ceca. Sections of the jejunum, duodenum, and ceca (depending on species of Eimeria) were taken at several time points between d zero and 14 post infection (PI) for mRNA expression analysis. Genes examined included one digestive enzyme, 7 peptide and amino acid transporters located on the brush border, 8 transporters located at the basolateral surface of the gut epithelium, and 5 sugar transporters. All 3 Eimeria species examined caused decrease in expression of brush border transporters particularly at d 5 to 7 PI, which corresponds to the time when pathology is greatest. The same pattern was seen in expression of sugar transporters. However, the expression of basolateral transporters differed among species. Eimeria tenella infection resulted in decreased expression of all basolateral transporters, while E. maxima infection caused increased expression of 2 genes and slight decrease in expression of the remaining 5 genes. Infection with E. acervulina resulted in increased expression at the height of infection of all but one basolateral transporter. In conclusion, Eimeria infection causes a general decrease in gene expression of sugar transporter and brush border AATs at the height of infection. However the expression of basolateral transporters is increased in E. maxima and E. acervulina infected birds. It is possible that decreased expression of brush border transporters in combination with

Administration of a dipeptidyl peptidase IV inhibitor enhances the intestinal adaptation in a mouse model of short bowel syndrome

DEFF Research Database (Denmark)

Okawada, Manabu; Holst, Jens Juul; Teitelbaum, Daniel H

2011-01-01

Glucagon-like peptide-2 induces small intestine mucosal epithelial cell proliferation and may have benefit for patients who suffer from short bowel syndrome. However, glucagon-like peptide-2 is inactivated rapidly in vivo by dipeptidyl peptidase IV. Therefore, we hypothesized that selectively inh...... inhibiting dipeptidyl peptidase IV would prolong the circulating life of glucagon-like peptide-2 and lead to increased intestinal adaptation after development of short bowel syndrome....

Central nervous system regulation of intestinal lipid and lipoprotein metabolism.

Science.gov (United States)

Farr, Sarah; Taher, Jennifer; Adeli, Khosrow

2016-02-01

In response to nutrient availability, the small intestine and brain closely communicate to modulate energy homeostasis and metabolism. The gut-brain axis involves complex nutrient sensing mechanisms and an integration of neuronal and hormonal signaling. This review summarizes recent evidence implicating the gut-brain axis in regulating lipoprotein metabolism, with potential implications for the dyslipidemia of insulin resistant states. The intestine and brain possess distinct mechanisms for sensing lipid availability, which triggers subsequent regulation of feeding, glucose homeostasis, and adipose tissue metabolism. More recently, central receptors, neuropeptides, and gut hormones that communicate with the brain have been shown to modulate hepatic and intestinal lipoprotein metabolism via parasympathetic and sympathetic signaling. Gut-derived glucagon-like peptides appear to be particularly important in modulating the intestinal secretion of chylomicron particles via a novel brain-gut axis. Dysregulation of these pathways may contribute to postprandial diabetic dyslipidemia. Emerging evidence implicates the central and enteric nervous systems in controlling many aspects of lipid and lipoprotein metabolism. Bidirectional communication between the gut and brain involving neuronal pathways and gut peptides is critical for regulating feeding and metabolism, and forms a neuroendocrine circuit to modulate dietary fat absorption and intestinal production of atherogenic chylomicron particles.

Regulatory signals for intestinal amino acid transporters and peptidases

International Nuclear Information System (INIS)

Ferraris, R.P.; Kwan, W.W.; Diamond, J.

1988-01-01

Dietary protein ultimately regulates many processes involved in protein digestion, but it is often unclear whether proteins themselves, peptides, or amino acids (AAs) are the proximate regulatory signal. Hence the authors compared several processes involved in protein digestion in mice adapted to one of three rations, identical except for containing 54% of either casein, a partial hydrolysate of casein, or a free AA mixture simulating a complete hydrolysate of casein. The authors measured brush-border uptakes of seven AAs that variously serve as substrates for four AA transporters, and brush-border and cytosolic activities of four peptidases. The three rations yielded essentially the same AA uptake rates. Peptidase activities tended to be lower on the AA ration than on the protein ration. In other studies, all three rations yielded the same rates of brush-border peptide uptake; protein is only modestly more effective than AAs at inducing synthesis of pancreatic proteases; and, depending on the animal species, protein is either much less or much more effective than AAs at stimulating release of cholecystokinin and hence of pancreatic enzymes. Thus the regulators of each process involved in protein digestion are not necessarily that process's substrate

Responses of mRNA expression of PepT1 in small intestine to ...

African Journals Online (AJOL)

To study the effect of circulation small peptides concentration on mRNA expression in small intestine, graded amount of soybean small peptides (SSP) were infused into lactating goats through duodenal fistulas. Peptide-bound amino acid (PBAA) concentration in arterial plasma and the mRNA expression of PepT1 was ...

Milk bioactive peptides and beta-casomorphins induce mucus release in rat jejunum.

Science.gov (United States)

Trompette, Aurélien; Claustre, Jean; Caillon, Fabienne; Jourdan, Gérard; Chayvialle, Jean Alain; Plaisancié, Pascale

2003-11-01

Intestinal mucus is critically involved in the protection of the mucosa. An enzymatic casein hydrolysate and beta-casomorphin-7, a mu-opioid peptide generated in the intestine during bovine casein digestion, markedly induce mucus discharge. Because shorter mu-opioid peptides have been described, the effects of the opioid peptides in casein, beta-casomorphin-7, -6, -4, -4NH2 and -3, and of opioid neuropeptides met-enkephalin, dynorphin A and (D-Ala2,N-Me-Phe4,glycinol5)enkephalin (DAMGO) on intestinal mucus secretion were investigated. The experiments were conducted with isolated perfused rat jejunum. Mucus secretion under the influence of beta-casomorphins and opioid neuropeptides administered intraluminally or intra-arterially was evaluated using an ELISA for rat intestinal mucus. Luminal administration of beta-casomorphin-7 (1.2 x 10(-4) mol/L) provoked a mucus discharge (500% of controls) that was inhibited by naloxone, a specific opiate receptor antagonist. Luminal beta-casomorphin-6, -4 and -4NH2 did not modify basal mucus secretion, whereas intra-arterial administration of beta-casomorphin-4 (1.2 x 10(-6) mol/L) induced a mucus discharge. In contrast, intra-arterial administration of the nonopioid peptide beta-casomorphin-3 did not release mucus. Among the opioid neuropeptides, intra-arterial infusion of Met-enkephalin or dynorphin-A did not provoke mucus secretion. In contrast, beta-endorphin (1.2 x 10(-8) to 1.2 x 10(-6) mol/L) induced a dose-dependent release of mucus (maximal response at 500% of controls). DAMGO (1.2 x 10(-6) mol/L), a mu-receptor agonist, also evoked a potent mucus discharge. Our findings suggest that mu-opioid neuropeptides, as well as beta-casomorphins after absorption, modulate intestinal mucus discharge. Milk opioid-derived peptides may thus be involved in defense against noxious agents and could have dietary and health applications.

Transport of the Glucosamine-Derived Browning Product Fructosazine (Polyhydroxyalkylpyrazine) Across the Human Intestinal Caco-2 Cell Monolayer: Role of the Hexose Transporters.

Science.gov (United States)

Bhattacherjee, Abhishek; Hrynets, Yuliya; Betti, Mirko

2017-06-14

The transport mechanism of fructosazine, a glucosamine self-condensation product, was investigated using a Caco-2 cell model. Fructosazine transport was assessed by measuring the bidirectional permeability coefficient across Caco-2 cells. The mechanism of transport was evaluated using phlorizin, an inhibitor of sodium-dependent glucose cotransporters (SGLT) 1 and 2, phloretin and quercetin, inhibitors of glucose transporters (GLUT) 1 and 2, transcytosis inhibitor wortmannin, and gap junction disruptor cytochalasin D. The role of hexose transporters was further studied using downregulated or overexpressed cell lines. The apparent permeability (P a,b ) of fructosazine was 1.30 ± 0.02 × 10 -6 cm/s. No significant (p > 0.05) effect was observed in fructosazine transport by adding wortmannin and cytochalasin D. The presence of phlorizin, phloretin, and quercetin decreased fructosazine transport. The downregulated GLUT cells line was unable to transport fructosazine. In human intestinal epithelial Caco-2 cells, GLUT1 or GLUT2 and SGLT are mainly responsible for fructosazine transport.

Electroacupuncture Inhibits Inflammation Reaction by Upregulating Vasoactive Intestinal Peptide in Rats with Adjuvant-Induced Arthritis

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Tian-Feng He

2011-01-01

Full Text Available Acupuncture is emerging as an alternative therapy for rheumatoid arthritis (RA. However, the molecular mechanism underlying this beneficial effect of acupuncture has not been fully understood. Here, we demonstrated that electroacupuncture at acupoints Zusanli (ST36, Xuanzhong (GB39; and Shenshu (BL23 markedly decreased the paw swelling and the histologic scores of inflammation in the synovial tissue, and reduced the body weight loss in an adjuvant-induced arthritis rat model. However, the electrical stimulation at nonacupoint did not produce any beneficial effects against the experimental arthritis. Most interestingly, the electroacupuncture treatment resulted in an enhanced immunostaining for vasoactive intestinal peptide (VIP, a potent anti-inflammatory neuropeptide, in the synovial tissue. Moreover, the VIP-immunostaining intensity was significantly negatively correlated with the scores of inflammation in the synovial tissue (r=−0.483, P=.0026. In conclusion, these findings suggest that electroacupuncture may offer therapeutic benefits for the treatment of RA, at least partially through the induction of VIP expression.

Transport of plutonium across isolated segments of the intestine of neonatal swine

International Nuclear Information System (INIS)

Sullivan, M.F.; Gorham, L.S.

1980-01-01

Absorption of 239 Pu was measured in neonatal swine gavaged with either 239 Pu(IV) or 239 Pu(VI) niitrate 1 day after birth. When they were killed, 1 or 3 wk later, retention of the Pu(VI) was about 50% greater than retention of Pu(IV). Studies with isolated intestinal segments indicated no appreciable difference in 238 Pu transport by the duodenum, midgut or terminal ileum, and a substantial decrease in absorption between 2 and 19 days after birth

Activation of intestinal epithelial Stat3 orchestrates tissue defense during gastrointestinal infection.

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Nadine Wittkopf

Full Text Available Gastrointestinal infections with EHEC and EPEC are responsible for outbreaks of diarrheal diseases and represent a global health problem. Innate first-line-defense mechanisms such as production of mucus and antimicrobial peptides by intestinal epithelial cells are of utmost importance for host control of gastrointestinal infections. For the first time, we directly demonstrate a critical role for Stat3 activation in intestinal epithelial cells upon infection of mice with Citrobacter rodentium - a murine pathogen that mimics human infections with attaching and effacing Escherichia coli. C. rodentium induced transcription of IL-6 and IL-22 in gut samples of mice and was associated with activation of the transcription factor Stat3 in intestinal epithelial cells. C. rodentium infection induced expression of several antimicrobial peptides such as RegIIIγ and Pla2g2a in the intestine which was critically dependent on Stat3 activation. Consequently, mice with specific deletion of Stat3 in intestinal epithelial cells showed increased susceptibility to C. rodentium infection as indicated by high bacterial load, severe gut inflammation, pronounced intestinal epithelial cell death and dissemination of bacteria to distant organs. Together, our data implicate an essential role for Stat3 activation in intestinal epithelial cells during C. rodentium infection. Stat3 concerts the host response to bacterial infection by controlling bacterial growth and suppression of apoptosis to maintain intestinal epithelial barrier function.

AcEST: DK950544 [AcEST

Lifescience Database Archive (English)

Full Text Available some 3 SCAF14756, whole genome shot... 77 3e-13 tr|A8IF50|A8IF50_9PERC Intestinal peptide transporter OS=Sebaste...|A8IF50_9PERC Intestinal peptide transporter OS=Sebastes nebulosus GN=SLC15A1 PE=2 SV=1 Length = 742 Score =

AcEST: DK951699 [AcEST

Lifescience Database Archive (English)

Full Text Available 8IF50_9PERC Intestinal peptide transporter OS=Sebaste... 93 8e-18 tr|A7ST97|A7ST97_NEMVE Predicted protein (...++D +L KY TI+YLS+ Y Sbjct: 66 ALCYLTPILGAIVADSWLGKYKTIVYLSIVY 96 >tr|A8IF50|A8IF50_9PERC Intestinal peptide transporter OS=Sebaste

[Substance P and vasoactive intestinal peptide in patients with progressive scleroderma. Determination of plasma level before and after autogenic training].

Science.gov (United States)

Haustein, U F; Weber, B; Seikowski, K

1995-02-01

In 12 patients suffering from systemic sclerosis (SSc) the influence of autogenic training on the plasma level of the neuropeptides substance P and vasoactive intestinal peptide (VIP) was studied. Compared with healthy controls the SSc patients exhibited significantly elevated levels of substance P (mean +/- SD: 7.1 +/- 3.2 pmol/l vs 1.6 +/- 1.6 pmol/l). Apart from variations the VIP plasma concentration did not significantly differ from that in healthy controls (mean +/- SD 10.7 +/- 7.1 pmol/l versus 12.0 +/- 5.3 pmol/l). Autogenic training did not bring about any significant changes in the plasma levels of neuropeptides.

The anti-epileptic drug substance vigabatrin inhibits taurine transport in intestinal and renal cell culture models

DEFF Research Database (Denmark)

Plum, Jakob Munk; Nøhr, Martha Kampp; Hansen, Steen H

2014-01-01

, such evidence does not preclude the involvement of other transporters. The aim of the present study was, therefore, to investigate if vigabatrin interacts with taurine transport. The uptake of taurine was measured in intestinal human Caco-2 and canine MDCK cell monolayers in the absence or presence of amino...... acids such as GABA and vigabatrin. Vigabatrin inhibits the uptake of taurine in Caco-2 and MDCK cells to 34±3 and 53±2%, respectively, at a concentration of 30mM. In Caco-2 cells the uptake of vigabatrin under neutral pH conditions is concentration-dependent and saturable with a Km-value of 27mM (log......Km is 1.43±0.09). In conclusion, the present study shows that vigabatrin was able to inhibit the uptake of taurine in intestinal and renal cell culture models. Furthermore, uptake of vigabatrin in Caco-2 cells under neutral pH conditions was concentration-dependent and saturable and suggesting...

Exogenous glucagon-like peptide-1 attenuates glucose absorption and reduces blood glucose concentration after small intestinal glucose delivery in critical illness.

Science.gov (United States)

Miller, Asaf; Deane, Adam M; Plummer, Mark P; Cousins, Caroline E; Chapple, Lee-Anne S; Horowitz, Michael; Chapman, Marianne J

2017-03-01

To evaluate the effect of exogenous glucagonlike peptide-1 (GLP-1) on small intestinal glucose absorption and blood glucose concentrations during critical illness. A prospective, blinded, placebo-controlled, cross-over, randomised trial in a mixed medical-surgical adult intensive care unit, with 12 mechanically ventilated critically ill patients, who were suitable for receiving small intestinal nutrient. On consecutive days, in a randomised order, participants received intravenous GLP-1 (1.2 pmol/ kg/min) or placebo (0.9% saline) as a continuous infusion over 270 minutes. After 6 hours of fasting, intravenous infusions of GLP-1 or placebo began at T = -30 min (in which T = time), with the infusion maintained at a constant rate until study completion at T = 240 min. At T = 0 min, a 100 mL bolus of mixed liquid nutrient meal (1 kcal/mL) containing 3 g of 3-O-methyl-D-gluco-pyranose (3-OMG), a marker of glucose absorption, was administered directly into the small intestine, via a post-pyloric catheter, over 6 minutes. Blood samples were taken at regular intervals for the measurement of plasma glucose and 3-OMG concentrations. Intravenous GLP-1 attenuated initial small intestinal glucose absorption (mean area under the curve [AUC] 0-30 for 3-OMG: GLP-1 group, 4.4 mmol/L/min [SEM, 0.9 mmol/L/min] v placebo group, 6.5 mmol/L/min [SEM, 1.0 mmol/L/min]; P = 0.01), overall small intestinal glucose absorption (mean AUC 0-240 for 3-OMG: GLP-1, 68.2 mmol/L/ min [SEM, 4.7 mmol/L/min] v placebo, 77.7 mmol/L/min [SEM, 4.4 mmol/lLmin]; P = 0.02), small intestinal glucose absorption and overall blood glucose concentration (mean AUC 0-240 for blood glucose: GLP-1, 2062 mmol/L/min [SEM, 111 mmol/L/min] v placebo 2328 mmol/L/min [SEM, 145 mmol/L/min]; P = 0.005). Short-term administration of exogenous GLP-1 reduces small intestinal glucose absorption for up to 4 hours during critical illness. This is likely to be an additional mechanism for the glucose-lowering effect of this agent.

Transport of sennosides and sennidines from Cassia angustifolia and Cassia senna across Caco-2 monolayers--an in vitro model for intestinal absorption.

Science.gov (United States)

Waltenberger, B; Avula, B; Ganzera, M; Khan, I A; Stuppner, H; Khan, S I

2008-05-01

Laxative effects of Senna preparations are mainly mediated by rheinanthrone, a metabolite formed in the intestinal flora from dianthrones. Nevertheless, it was not clear whether dianthrones are bioavailable at all and contribute to the overall effects of this important medicinal plant. Using the Caco-2 human colonic cell line as an in vitro model of the human intestinal mucosal barrier, the bioavailability of dianthrones was studied in apical to basolateral (absorptive) and basolateral to apical (secretive) direction. Permeability coefficients (P(c)) and percent transport were calculated based on quantitations by HPLC. From the data obtained it was concluded that sennosides A and B, as well as their aglycones sennidine A and B are transported through the Caco-2 monolayers in a concentration-dependent manner and their transport was linear with time. The absorption in apical to basolateral direction was poor and P(c) values were comparable to mannitol. The transport was higher in the secretory direction, indicating a significant efflux (e.g. by efflux pumps) of the (poorly) absorbed compounds in the intestinal lumen again. Our findings support the general understanding that the laxative effects of Senna are explainable mainly by metabolites and not by the natively present dianthrones.

Intestinal Iron Homeostasis and Colon Tumorigenesis

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Yatrik M. Shah

2013-06-01

Full Text Available Colorectal cancer (CRC is the third most common cause of cancer-related deaths in industrialized countries. Understanding the mechanisms of growth and progression of CRC is essential to improve treatment. Iron is an essential nutrient for cell growth. Iron overload caused by hereditary mutations or excess dietary iron uptake has been identified as a risk factor for CRC. Intestinal iron is tightly controlled by iron transporters that are responsible for iron uptake, distribution, and export. Dysregulation of intestinal iron transporters are observed in CRC and lead to iron accumulation in tumors. Intratumoral iron results in oxidative stress, lipid peroxidation, protein modification and DNA damage with consequent promotion of oncogene activation. In addition, excess iron in intestinal tumors may lead to increase in tumor-elicited inflammation and tumor growth. Limiting intratumoral iron through specifically chelating excess intestinal iron or modulating activities of iron transporter may be an attractive therapeutic target for CRC.

Plasticity of osmoregulatory function in the killifish intestine: drinking rates, salt and water transport, and gene expression after freshwater transfer.

Science.gov (United States)

Scott, Graham R; Schulte, Patricia M; Wood, Chris M

2006-10-01

We have explored intestinal function in the euryhaline killifish Fundulus heteroclitus after transfer from brackish water (10% seawater) to fresh water. Plasma Na+ and Cl- concentrations fell at 12 h post-transfer, but recovered by 7 days. Drinking rate decreased substantially at 12 h (32% of control value) and remained suppressed after 3 and 7 days in fresh water (34 and 43%). By contrast, there was a transient increase in the capacity for water absorption measured across isolated intestines in vitro (3.3- and 2.6-fold at 12 h and 3 days), which returned to baseline after 7 days. These changes in water absorption could be entirely accounted for by changes in net ion flux: there was an extremely strong correlation (R2=0.960) between water absorption and the sum of net Na+ and net Cl- fluxes (3.42+/-0.10 microl water micromol(-1) ion). However, enhanced ion transport across the intestine in fresh water would probably not increase water uptake in vivo, because the drinking rate was far less than the capacity for water absorption across the intestine. The increased intestinal ion absorption after freshwater transfer may instead serve to facilitate ion absorption from food when it is present in the gut. Modulation of net ion flux occurred without changes in mRNA levels of many ion transporters (Na+/K+-ATPase alpha(1a), carbonic anhydrase 2, CFTR Cl- channel, Na+/K+/2Cl- cotransporter 2, and the signalling protein 14-3-3a), and before a measured increase in Na+/K+-ATPase activity at 3 days, suggesting that there is some other mechanism responsible for increasing ion transport. Interestingly, net Cl- flux always exceeded net Na+ flux, possibly to help maintain Cl- balance and/or facilitate bicarbonate excretion. Our results suggest that intestinal NaCl absorption from food is important during the period of greatest ionic disturbance after transfer to fresh water, and provide further insight into the mechanisms of euryhalinity in killifish.

Drug Transporters in the Intestine

DEFF Research Database (Denmark)

Steffansen, Bente

2016-01-01

to the intestinal exsorptive DTs. An example is the API sulfasalazine, which is a substrate for breast cancer resistance protein (BCRP)/ABCG2. Sulfasalazine absorption is found to increase when human volunteers are administered high concentrations together with the inhibitor and spice curcumin. In conclusion...

The ontogeny of nutrient transporter and digestive enzyme gene expression in domestic pigeon (Columba livia) intestine and yolk sac membrane during pre- and posthatch development.

Science.gov (United States)

Dong, X Y; Wang, Y M; Yuan, C; Zou, X T

2012-08-01

To better understand the digestive capacity in domestic pigeons (Columba livia), this study was conducted to evaluate nutrient transporters and digestive enzymes gene expression in small intestine and yolk sac membrane (YSM) during pre- and posthatch development. We investigated the oligopeptide transporter Pept1, sodium glucose transporter SGLT1, glucose transporter GLUT2, aminopeptidase-N (APN), and sucrase-isomaltase (SI). Intestine was collected at embryo d 12, 14, and 16, day of hatch, and d 1, 3, 5, 8, and 14 posthatch. The YSM was collected at embryo d 12, 14, 16, and day of hatch. The cDNA fragments for Pept1, SGLT1, GLUT2, APN, and SI were isolated and cloned using reverse-transcription PCR. The sequences data showed that these genes were highly identical to the gene of chicken. The mRNA expression of each gene was assayed using real-time PCR. Expression of intestinal nutrient transporters increased linearly (Ppigeons and establish a foundation for future research on the nutrients requirements for young pigeons.

Somatostatin, substance P and calcitonin gene-related peptide-positive intramural nerve structures of the human large intestine affected by carcinoma.

Directory of Open Access Journals (Sweden)

Jerzy Kaleczyc

2010-11-01

Full Text Available The aim of this study was to investigate the arrangement and chemical coding of enteric nerve structures in the human large intestine affected by cancer. Tissue samples comprising all layers of the intestinal wall were collected during surgery form both morphologically unchanged and pathologically altered segments of the intestine (n=15, and fixed by immersion in buffered paraformaldehyde solution. The cryostat sections were processed for double-labelling immunofluorescence to study the distribution of the intramural nerve structures (visualized with antibodies against protein gene-product 9.5 and their chemical coding using antibodies against somatostatin (SOM, substance P (SP and calcitonin gene-related peptide (CGRP. The microscopic observations revealed distinct morphological differences in the enteric nerve system structure between the region adjacent to the cancer invaded area and the intact part of the intestine. In general, infiltration of the cancer tissue resulted in the gradual (depending on the grade of invasion first decomposition and reduction to final partial or complete destruction and absence of the neuronal elements. A comparative analysis of immunohistochemically labeled sections (from the unchanged and pathologically altered areas revealed a statistically significant decrease in the number of CGRP-positive neurons and nerve fibres in both submucous and myenteric plexuses in the transitional zone between morphologically unchanged and cancer-invaded areas. In this zone, a decrease was also observed in the density of SP-positive nerve fibres in all intramural plexuses. Conversely, the investigations demonstrated statistically insignificant differences in number of SP- and SOM-positive neurons and a similar density of SOM-positive nerve fibres in the plexuses of the intact and pathologically changed areas. The differentiation between the potential adaptive changes in ENS or destruction of its elements by cancer invasion should be

Carrier-mediated ¿-aminobutyric acid transport across the basolateral membrane of human intestinal Caco-2 cell monolayers

DEFF Research Database (Denmark)

Nielsen, Carsten Uhd; Carstensen, Mette; Brodin, Birger

2012-01-01

and the anticancer prodrug d-aminolevulinic acid across the apical membrane of small intestinal enterocytes. Little is however known about the basolateral transport of these substances. We investigated basolateral transport of GABA in mature Caco-2 cell monolayers using isotope studies. Here we report that, at least...... two transporters seem to be involved in the basolateral transport of GABA. The basolateral uptake consisted of a high-affinity system with a K(m) of 290µM and V(max) of 75pmolcm(-2)min(-1) and a low affinity system with a K(m) of approximately 64mM and V(max) of 1.6nmolcm(-2)min(-1). The high...

Prevalence of intestinal parasites among workers involved in collection, transportation and recycling of wastes in the Pars Special Economic Energy Zone, Bushehr

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MoradAli Fouladvand

2014-01-01

Full Text Available Abstract Background Intestinal parasitic infections are of one most important problems in developing countries and job is one of the most important factors determining the rate of intestinal parasitic infections. Persons who deal with waste elimination and recycling, due to close contact with infectious sources are more likely to be infected than others. Because of industrialization, population density and immigrants residing in Assaluyeh region , and due to the lack of history of a study for intestinal parasitic infection, the prevalence rate of intestinal parasitic infections among workers in the collection, transportation and recycling of wastes in the Pars Special Economic Energy Zone was evaluated. Material and methods: In a descriptive cross-sectional study, demographic questionaire was completed for each person, Stool samples were taken and sample containers were transferred to parasitology research laboratory of university. Samples were examined for intestinal parasites by preparing direct smear (wet mount and formalin-ether sedimentation technique. Data were collected by questionnaire and analyzed using SPSS 15.0 software and Chi square test. Results: The results showed that 37.3% of samples were infected at least with one intestinal parasite, 10.7% of samples were infected with more than one parasite. Giardia lamblia (6% and Entamoeba coli (13/4%, showed the highest infection rate among all parasite species. Prevalence rate of intestinal parasites in worker from Nakhl-e- Taghi municipality was higher than other region of the study area. Conclusion : Job type and duration of contact with infectious source play important roles in determining rate of intestinal parasitic infection. Workers involved in collection, transportation and recycling of wastes are more at risk of intestinal parasitic infections than others. Therfore, providing personal protective equipments and health education in this group can play an important role in community

Effect of feeding soybean meal and differently processed peas on intestinal morphology and functional glucose transport in the small intestine of broilers.

Science.gov (United States)

Röhe, I; Boroojeni, F Goodarzi; Zentek, J

2017-09-01

Peas are locally grown legumes being rich in protein and starch. However, the broad usage of peas as a feed component in poultry nutrition is limited to anti-nutritional factors, which might impair gut morphology and function. This study investigated the effect of feeding raw or differently processed peas compared with feeding a soybean meal-based control diet (C) on intestinal morphology and nutrient transport in broilers. A total of 360 day-old broiler chicks were fed with one of the following diets: The C diet, and 3 diets containing raw peas (RP), fermented peas (FP) and enzymatically pre-digested peas (EP), each supplying 30% of dietary crude protein. After 35 d, jejunal samples of broilers were taken for analyzing histomorphological parameters, active glucose transport in Ussing chambers and the expression of genes related to glucose absorption, intestinal permeability and cell maturation. Villus length (P = 0.017) and crypt depth (P = 0.009) of EP-fed broilers were shorter compared to birds received C. The villus surface area was larger in broilers fed C compared to those fed with the pea-containing feed (P = 0.005). Glucose transport was higher for broilers fed C in comparison to birds fed with the EP diet (P = 0.044). The sodium-dependent glucose co-transporter 1 (SGLT-1) expression was down-regulated in RP (P = 0.028) and FP (P = 0.015) fed broilers. Correlation analyses show that jejunal villus length negatively correlates with the previously published number of jejunal intraepithelial T cells (P = 0.014) and that jejunal glucose transport was negatively correlated with the occurrence of jejunal intraepithelial leukocytes (P = 0.041). To conclude, the feeding of raw and processed pea containing diets compared to a soybean based diet reduced the jejunal mucosal surface area of broilers, which on average was accompanied by lower glucose transport capacities. These morphological and functional alterations were associated with observed mucosal immune

Chemical form of selenium affects its uptake, transport, and glutathione peroxidase activity in the human intestinal Caco-2 cell model.

Science.gov (United States)

Zeng, Huawei; Jackson, Matthew I; Cheng, Wen-Hsing; Combs, Gerald F

2011-11-01

Determining the effect of selenium (Se) chemical form on uptake, transport, and glutathione peroxidase activity in human intestinal cells is critical to assess Se bioavailability at nutritional doses. In this study, we found that two sources of L-selenomethionine (SeMet) and Se-enriched yeast each increased intracellular Se content more effectively than selenite or methylselenocysteine (SeMSC) in the human intestinal Caco-2 cell model. Interestingly, SeMSC, SeMet, and digested Se-enriched yeast were transported at comparable efficacy from the apical to basolateral sides, each being about 3-fold that of selenite. In addition, these forms of Se, whether before or after traversing from apical side to basolateral side, did not change the potential to support glutathione peroxidase (GPx) activity. Although selenoprotein P has been postulated to be a key Se transport protein, its intracellular expression did not differ when selenite, SeMSC, SeMet, or digested Se-enriched yeast was added to serum-contained media. Taken together, our data show, for the first time, that the chemical form of Se at nutritional doses can affect the absorptive (apical to basolateral side) efficacy and retention of Se by intestinal cells; but that, these effects are not directly correlated to the potential to support GPx activity.

Intestinal Colonization Dynamics of Vibrio cholerae.

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Salvador Almagro-Moreno

2015-05-01

Full Text Available To cause the diarrheal disease cholera, Vibrio cholerae must effectively colonize the small intestine. In order to do so, the bacterium needs to successfully travel through the stomach and withstand the presence of agents such as bile and antimicrobial peptides in the intestinal lumen and mucus. The bacterial cells penetrate the viscous mucus layer covering the epithelium and attach and proliferate on its surface. In this review, we discuss recent developments and known aspects of the early stages of V. cholerae intestinal colonization and highlight areas that remain to be fully understood. We propose mechanisms and postulate a model that covers some of the steps that are required in order for the bacterium to efficiently colonize the human host. A deeper understanding of the colonization dynamics of V. cholerae and other intestinal pathogens will provide us with a variety of novel targets and strategies to avoid the diseases caused by these organisms.

In vivo evaluation of an oral drug delivery system for peptides based on S-protected thiolated chitosan.

Science.gov (United States)

Dünnhaupt, Sarah; Barthelmes, Jan; Iqbal, Javed; Perera, Glen; Thurner, Clemens C; Friedl, Heike; Bernkop-Schnürch, Andreas

2012-06-28

The aim of the present study was the development and evaluation in vitro as well as in vivo of an oral delivery system based on a novel type of thiolated chitosan, so-called S-protected thiolated chitosan, for the peptide drug antide. The sulfhydryl ligand thioglycolic acid (TGA) was covalently attached to chitosan (CS) in the first step of modification. In the second step, these thiol groups of thiolated chitosan were protected by disulfide bond formation with the thiolated aromatic residue 6-mercaptonicotinamide (6-MNA). Absorptive transport studies of antide were evaluated ex vivo using rat intestinal mucosa. Matrix tablets of each polymer sample were prepared and their effect on the absorption of antide evaluated in vivo in male Sprague-Dawley rats. In addition, tablets were examined in terms of their disintegration, swelling and drug release behavior. The resulting S-protected thiomer (TGA-MNA) exhibited 840μmol of covalently linked 6-MNA per gram thiomer. Based on the implementation of this hydrophobic ligand on the thiolated backbone, the disintegration behavior was reduced greatly and a controlled release of the peptide could be achieved. Furthermore, permeation studies with TGA-MNA on rat intestine revealed a 4.5-fold enhanced absorptive transport of the peptide in comparison to antide in solution. Additional in vivo studies confirmed the potential of this novel conjugate. Oral administration of antide in solution led to only very small detectable quantities in plasma with an absolute and relative bioavailability (BA) of 0.003 and 0.03%, only. In contrast, with antide incorporated in TGA-MNA matrix tablets an absolute and relative BA of 1.4 and 10.9% could be reached, resulting in a 421-fold increased area under the plasma concentration time curve (AUC) compared to the antide solution. According to these results, S-protected thiolated chitosan as oral drug delivery system might be a valuable tool for improving the bioavailability of peptides. Copyright �

Human Milk: Bioactive Proteins/Peptides and Functional Properties.

Science.gov (United States)

Lönnerdal, Bo

2016-06-23

Breastfeeding has been associated with many benefits, both in the short and in the long term. Infants being breastfed generally have less illness and have better cognitive development at 1 year of age than formula-fed infants. Later in life, they have a lower risk of obesity, diabetes and cardiovascular disease. Several components in breast milk may be responsible for these different outcomes, but bioactive proteins/peptides likely play a major role. Some proteins in breast milk are comparatively resistant towards digestion and may therefore exert their functions in the gastrointestinal tract in intact form or as larger fragments. Other milk proteins may be partially digested in the upper small intestine and the resulting peptides may exert functions in the lower small intestine. Lactoferrin, lysozyme and secretory IgA have been found intact in the stool of breastfed infants and are therefore examples of proteins that are resistant against proteolytic degradation in the gut. Together, these proteins serve protective roles against infection and support immune function in the immature infant. α-lactalbumin, β-casein, κ-casein and osteopontin are examples of proteins that are partially digested in the upper small intestine, and the resulting peptides influence functions in the gut. Such functions include stimulation of immune function, mineral and trace element absorption and defense against infection. © 2016 Nestec Ltd., Vevey/S. Karger AG, Basel.

Vasoactive intestinal peptide and somatostatin in the plasma and sigmoid mucosa in irritable bowel syndrome

International Nuclear Information System (INIS)

Zhang Ru; Wang Fuxian

2004-01-01

To investigate the possible role and clinical significance of vasoactive intestinal peptide (VIP) and somatostatin(SS) in the irritable bowel syndrome (IBS), the VIP and SS in the plasma and sigmoid mucosa were measured by radioimmunoassay in the control group and the IBS group. The VIP concentration in the plasma and sigmoid mucosa of the IBS patients with constipation was significantly higher than that of the control group (P<0.01), while that of the IBS patients with diarrhea was significantly lower than that of the control group (P<0.05). The SS concentration in two sites was significantly elevated in IBS patients of both types and was significantly higher in IBS with constipation than in IBS with diarrhea (P<0.05). Conclusion: The VIP and SS in IBS are abnormal, which might play a role in the pathogenesis of IBS. The plasma and mucosa concenration of VIP and SS in two kinds of IBS patients are significantly different, which indicates that there might be different pathophysiological basis involved in the pathogenesis of the two kinds of IBS patients. (authors)

Identification of New Anti-inflammatory Peptides from Zein Hydrolysate after Simulated Gastrointestinal Digestion and Transport in Caco-2 Cells.

Science.gov (United States)

Liang, Qiufang; Chalamaiah, Meram; Ren, Xiaofeng; Ma, Haile; Wu, Jianping

2018-02-07

Chronic inflammation is an underlying contributor to various chronic diseases. The objectives of this study were to investigate the anti-inflammatory activity of zein hydrolysate after simulated gastrointestinal digestion and Caco-2 cell absorption and to identify novel anti-inflammatory peptides after transport across Caco-2 cells. Three zein hydrolysates were prepared and further digested using gastrointestinal proteases; their transports were studied in Caco-2 cells. Anti-inflammatory activity was studied in endothelial EA.hy926 cells. Three zein hydrolysates and their digests significantly decreased the expression of tumor necrosis factor-α (TNF-α) induced pro-inflammatory vascular cell adhesion molecule-1 (VCAM-1) by 37.3-66.0%. Eleven novel peptides with 5-9 amino acid residues were sequenced; three peptides showed strong anti-inflammatory activity by inhibiting the VCAM-1 by 54-38.9% and intercellular cell adhesion molecule-1 (ICAM-1) by 36.5-28.6% at 0.2 mM. A new approach to identify novel anti-inflammatory peptides that could survive gastrointestinal digestion and absorption was developed.

Glucagon-like peptide-1 (GLP-1) receptor agonism or DPP-4 inhibition does not accelerate neoplasia in carcinogen treated mice

DEFF Research Database (Denmark)

Kissow, Hannelouise; Hartmann, Bolette; Holst, Jens Juul

2012-01-01

Glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) are secreted in parallel from the intestinal endocrine cells after nutrient intake. GLP-1 is an incretin hormone and analogues are available for the treatment of type 2 diabetes mellitus (T2DM). GLP-2 is an intestinal growth horm...

Expression of Trans- and Paracellular Calcium and Magnesium Transport Proteins in Renal and Intestinal Epithelia During Lactation

DEFF Research Database (Denmark)

Beggs, Megan R; Appel, Ida; Svenningsen, Per

2017-01-01

Significant alterations in maternal calcium (Ca2+) and magnesium (Mg2+) balance occur during lactation. Ca2+ is the primary divalent cation mobilized into breast milk by demineralization of the skeleton and alterations in intestinal and renal Ca2+ transport. Mg2+ is also concentrated in breast milk...

The small intestinal epithelia of beef steers differentially express sugar transporter messenger ribonucleic acid in response to abomasal versus ruminal infusion of starch hydrolysate.

Science.gov (United States)

Liao, S F; Harmon, D L; Vanzant, E S; McLeod, K R; Boling, J A; Matthews, J C

2010-01-01

In mammals, the absorption of monosaccharides from small intestinal lumen involves at least 3 sugar transporters (SugT): sodium-dependent glucose transporter 1 (SGLT1; gene SLC5A1) transports glucose and galactose, whereas glucose transporter (GLUT) 5 (GLUT5; gene SLC2A5) transports fructose, across the apical membrane of enterocytes. In contrast, GLUT2 (gene SLC2A2) transports all of these sugars across basolateral and apical membranes. To compare the distribution patterns and sensitivity with nutritional regulation of these 3 SugT mRNA in beef cattle small intestinal tissue, 18 ruminally and abomasally catheterized Angus steers (BW approximately 260 kg) were assigned to water (control), ruminal cornstarch (partially hydrolyzed by alpha-amylase; SH), or abomasal SH infusion treatments (n = 6) and fed an alfalfa-cube-based diet at 1.3 x NE(m) requirement. The SH infusions amounted to 20% of ME intake. After 14- or 16-d of infusion, steers were killed; duodenal, jejunal, and ileal epithelia harvested; and total RNA extracted. The relative amount of SugT mRNA in epithelia was determined using real-time reverse transcription-PCR quantification methods. Basal expression of GLUT2 and SGLT1 mRNA was greater (P content of GLUT5 mRNA was greater (P content of GLUT5 mRNA in small intestinal epithelia was not affected (P > or = 0.16) by either SH infusion treatment. In contrast, GLUT2 and SGLT1 mRNA content in the ileal epithelium was increased (P content also was increased (P = 0.07) by 64% after ruminal SH infusion. These results demonstrate that the ileum of beef cattle small intestine adapts to an increased luminal supply of glucose by increasing SGLT1 and GLUT2 mRNA content, whereas increased ruminal SH supply results in duodenal upregulation of SGLT1 mRNA content. These adaptive responses of GLUT2 and SGLT1 mRNA to abomasal or ruminal SH infusion suggest that beef cattle can adapt to increase their carbohydrate assimilation through small intestinal epithelia, assuming

Gintonin absorption in intestinal model systems

Directory of Open Access Journals (Sweden)

Byung-Hwan Lee

2018-01-01

Conclusion: The present study shows that gintonin could be absorbed in the intestine through transcellular and paracellular diffusion, and active transport. In addition, the lipid component of gintonin might play a key role in its intestinal absorption.

Structure-activity studies of vasoactive intestinal peptide (VIP): cyclic disulfide analogs.

Science.gov (United States)

Bolin, D R; Cottrell, J; Garippa, R; O'Neill, N; Simko, B; O'Donnell, M

1993-02-01

Analogs of vasoactive intestinal peptide with cysteine residues incorporated at selected sites within the sequence were prepared by solid phase methods, oxidized to the corresponding cyclic disulfides and purified to homogeneity by preparative HPLC. The cyclic compounds were assayed as smooth muscle relaxants on isolated guinea pig trachea, as bronchodilators in vivo in guinea pigs, and for binding to VIP receptors in guinea pig lung membranes. Of the analogs prepared at the N-terminus, one compound, Ac-[D-Cys6,D-Cys11,Lys12,Nle17,Val26,Th r28]-VIP, was found to be a full agonist with slightly more than one tenth the potency of native VIP. Most other cyclic analogs in the N-terminal region were found to be inactive. A second analog, Ac-[Lys12,Cys17,Val26,Cys28]-VIP, was also found to be a full agonist with potency about one third that of native VIP. Furthermore, this compound was active as a bronchodilator in vivo in guinea pig, but with somewhat diminished potency as compared to native VIP. Strikingly, this cyclic compound was found to have significantly longer duration of action (> 40 min) when compared to an analogous acyclic compound (5 min). The conformational restrictions imposed by formation of the cyclic ring structures may have stabilized the molecule to degradation, thus enhancing the effective duration of action. Analysis of this series of cyclic analogs has also yielded information about the requirements for the receptor-active conformation of VIP.

Anxiety, Depression, and the Microbiome: A Role for Gut Peptides.

Science.gov (United States)

Lach, Gilliard; Schellekens, Harriet; Dinan, Timothy G; Cryan, John F

2018-01-01

The complex bidirectional communication between the gut and the brain is finely orchestrated by different systems, including the endocrine, immune, autonomic, and enteric nervous systems. Moreover, increasing evidence supports the role of the microbiome and microbiota-derived molecules in regulating such interactions; however, the mechanisms underpinning such effects are only beginning to be resolved. Microbiota-gut peptide interactions are poised to be of great significance in the regulation of gut-brain signaling. Given the emerging role of the gut-brain axis in a variety of brain disorders, such as anxiety and depression, it is important to understand the contribution of bidirectional interactions between peptide hormones released from the gut and intestinal bacteria in the context of this axis. Indeed, the gastrointestinal tract is the largest endocrine organ in mammals, secreting dozens of different signaling molecules, including peptides. Gut peptides in the systemic circulation can bind cognate receptors on immune cells and vagus nerve terminals thereby enabling indirect gut-brain communication. Gut peptide concentrations are not only modulated by enteric microbiota signals, but also vary according to the composition of the intestinal microbiota. In this review, we will discuss the gut microbiota as a regulator of anxiety and depression, and explore the role of gut-derived peptides as signaling molecules in microbiome-gut-brain communication. Here, we summarize the potential interactions of the microbiota with gut hormones and endocrine peptides, including neuropeptide Y, peptide YY, pancreatic polypeptide, cholecystokinin, glucagon-like peptide, corticotropin-releasing factor, oxytocin, and ghrelin in microbiome-to-brain signaling. Together, gut peptides are important regulators of microbiota-gut-brain signaling in health and stress-related psychiatric illnesses.

Gut hormones in the treatment of short-bowel syndrome and intestinal failure

DEFF Research Database (Denmark)

Jeppesen, Palle B

2015-01-01

PURPOSE OF REVIEW: The approval of teduglutide, a recombinant analog of human glucagon-like peptide (GLP) 2, by the US Food and Drug Administration (Gattex) and the European Medicines Agency (Revestive) has illustrated the potential of selected gut hormones as treatments in patients with short......-bowel syndrome and intestinal failure. Gut hormones may improve the structural and functional intestinal adaptation following intestinal resection by decreasing a rapid gastric emptying and hypersecretion, by increasing the intestinal blood flow, and by promoting intestinal growth. This review summarizes......-1 may be less potent. Synergistic effects may be seen by co-treatment with GLP-2. SUMMARY: Gut hormones promote intestinal adaptation and absorption, decreasing fecal losses, thereby decreasing or even eliminating the need for parenteral support. This will aid the intestinal rehabilitation...

The H2 receptor antagonist nizatidine is a P-glycoprotein substrate: characterization of its intestinal epithelial cell efflux transport.

Science.gov (United States)

Dahan, Arik; Sabit, Hairat; Amidon, Gordon L

2009-06-01

The aim of this study was to elucidate the intestinal epithelial cell efflux transport processes that are involved in the intestinal transport of the H(2) receptor antagonist nizatidine. The intestinal epithelial efflux transport mechanisms of nizatidine were investigated and characterized across Caco-2 cell monolayers, in the concentration range 0.05-10 mM in both apical-basolateral (AP-BL) and BL-AP directions, and the transport constants of P-glycoprotein (P-gp) efflux activity were calculated. The concentration-dependent effects of various P-gp (verapamil, quinidine, erythromycin, ketoconazole, and cyclosporine A), multidrug resistant-associated protein 2 (MRP2; MK-571, probenecid, indomethacin, and p-aminohipuric acid), and breast cancer resistance protein (BCRP; Fumitremorgin C) inhibitors on nizatidine bidirectional transport were examined. Nizatidine exhibited 7.7-fold higher BL-AP than AP-BL Caco-2 permeability, indicative of net mucosal secretion. All P-gp inhibitors investigated displayed concentration-dependent inhibition on nizatidine secretion in both directions. The IC(50) of verapamil on nizatidine P-gp secretion was 1.2 x 10(-2) mM. In the absence of inhibitors, nizatidine displayed concentration-dependent secretion, with one saturable (J(max) = 5.7 x 10(-3) nmol cm(-2) s(-1) and K(m) = 2.2 mM) and one nonsaturable component (K(d) = 7 x 10(-4) microL cm(-2) s(-1)). Under complete P-gp inhibition, nizatidine exhibited linear secretory flux, with a slope similar to the nonsaturable component. V(max) and K(m) estimated for nizatidine P-gp-mediated secretion were 4 x 10(-3) nmol cm(-2) s(-1) and 1.2 mM, respectively. No effect was obtained with the MRP2 or the BCRP inhibitors. Being a drug commonly used in pediatrics, adults, and elderly, nizatidine susceptibility to efflux transport by P-gp revealed in this paper may be of significance in its absorption, distribution, and clearance, as well as possible drug-drug interactions.

The Relationship between Glucagon-Like Peptide 2 and Feeding Intolerance in Preterm Infants

DEFF Research Database (Denmark)

Ozer, Esra Arun; Holst, Jens Juul; Duman, Nuray

2008-01-01

Glucagon-like peptide 2 (GLP-2) is a hormone produced primarily in the distal intestine, stimulated by enteral nutrients, and playing diverse roles in the intestinal adaptation and growth. We aimed to investigate whether GLP-2 may play a role in the development of feeding intolerance which is a c...... with low levels of GLP-2 carry a risk for development of feeding intolerance. It may, therefore, be of relevance to investigate the therapeutic and prophylactic effects of GLP-2 administration in the preterm babies.......Glucagon-like peptide 2 (GLP-2) is a hormone produced primarily in the distal intestine, stimulated by enteral nutrients, and playing diverse roles in the intestinal adaptation and growth. We aimed to investigate whether GLP-2 may play a role in the development of feeding intolerance which...... is a common problem in preterm newborns resulting from the intestinal immaturity. The study included 20 term and 28 preterm neonates. Of preterm babies, 13 showed feeding intolerance fulfilling at least one of the following criteria: abdominal distension, increased gastric residual volume and presence of bile...

Peptide-membrane interactions of arginine-tryptophan peptides probed using quartz crystal microbalance with dissipation monitoring.

KAUST Repository

Rydberg, Hanna A

2014-04-18

Membrane-active peptides include peptides that can cross cellular membranes and deliver macromolecular cargo as well as peptides that inhibit bacterial growth. Some of these peptides can act as both transporters and antibacterial agents. It is desirable to combine the knowledge from these two different fields of membrane-active peptides into design of new peptides with tailored actions, as transporters of cargo or as antibacterial substances, targeting specific membranes. We have previously shown that the position of the amino acid tryptophan in the peptide sequence of three arginine-tryptophan peptides affects their uptake and intracellular localization in live mammalian cells, as well as their ability to inhibit bacterial growth. Here, we use quartz crystal microbalance with dissipation monitoring to assess the induced changes caused by binding of the three peptides to supported model membranes composed of POPC, POPC/POPG, POPC/POPG/cholesterol or POPC/lactosyl PE. Our results indicate that the tryptophan position in the peptide sequence affects the way these peptides interact with the different model membranes and that the presence of cholesterol in particular seems to affect the membrane interaction of the peptide with an even distribution of tryptophans in the peptide sequence. These results give mechanistic insight into the function of these peptides and may aid in the design of membrane-active peptides with specified cellular targets and actions.

Peptide-membrane interactions of arginine-tryptophan peptides probed using quartz crystal microbalance with dissipation monitoring.

KAUST Repository

Rydberg, Hanna A; Kunze, Angelika; Carlsson, Nils; Altgä rde, Noomi; Svedhem, Sofia; Nordé n, Bengt

2014-01-01

Membrane-active peptides include peptides that can cross cellular membranes and deliver macromolecular cargo as well as peptides that inhibit bacterial growth. Some of these peptides can act as both transporters and antibacterial agents. It is desirable to combine the knowledge from these two different fields of membrane-active peptides into design of new peptides with tailored actions, as transporters of cargo or as antibacterial substances, targeting specific membranes. We have previously shown that the position of the amino acid tryptophan in the peptide sequence of three arginine-tryptophan peptides affects their uptake and intracellular localization in live mammalian cells, as well as their ability to inhibit bacterial growth. Here, we use quartz crystal microbalance with dissipation monitoring to assess the induced changes caused by binding of the three peptides to supported model membranes composed of POPC, POPC/POPG, POPC/POPG/cholesterol or POPC/lactosyl PE. Our results indicate that the tryptophan position in the peptide sequence affects the way these peptides interact with the different model membranes and that the presence of cholesterol in particular seems to affect the membrane interaction of the peptide with an even distribution of tryptophans in the peptide sequence. These results give mechanistic insight into the function of these peptides and may aid in the design of membrane-active peptides with specified cellular targets and actions.

The VPAC2 agonist peptide histidine isoleucine (PHI) up-regulates glutamate transport in the corpus callosum of a rat model of amyotrophic lateral sclerosis (hSOD1G93A) by inhibiting caspase-3 mediated inactivation of GLT-1a.

Science.gov (United States)

Goursaud, Stéphanie; Focant, Marylène C; Berger, Julie V; Nizet, Yannick; Maloteaux, Jean-Marie; Hermans, Emmanuel

2011-10-01

Degeneration of corpus callosum appears in patients with amyotrophic lateral sclerosis (ALS) before clinical signs of upper motor neuron death. Considering the ALS-associated impairment of astrocytic glutamate uptake, we have characterized the expression and activity of the glutamate transporter isoforms GLT-1a and GLT-1b in the corpus callosum of transgenic rats expressing a mutated form of the human superoxide dismutase 1 (hSOD1(G93A)). We have also studied the effect of peptide histidine isoleucine (PHI), a vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase-activating polypeptide (PACAP) receptor 2 (VPAC(2)) agonist on glutamate transporters both in vivo and in callosal astrocytes. Before the onset of motor symptoms, the expression of both transporter isoforms was correlated with a constitutive activity of caspase-3. This enzyme participates in the down-regulation of GLT-1 in ALS, and here we demonstrated its involvement in the selective degradation of GLT-1a in the white matter. A single stereotactic injection of PHI into the corpus callosum of symptomatic rats decreased caspase-3 activity and promoted GLT-1a expression and uptake activity. Together, with evidence for a reduced expression of prepro-VIP/PHI mRNA in the corpus callosum of transgenic animals, these data shed light on the modulatory role of the VIP/PHI system on the glutamatergic transmission in ALS.

A role for the serotonin reuptake transporter in the brain and intestinal features of autism spectrum disorders and developmental antidepressant exposure.

Science.gov (United States)

Margolis, Kara Gross

2017-10-01

Many disease conditions considered CNS-predominant harbor significant intestinal comorbidities. Serotonin (5-HT) and the serotonin reuptake transporter (SERT) have increasingly been shown to play important roles in both brain and intestinal development and long-term function. 5-HT and SERT may thus modulate critical functions in the development and perpetuation of brain-gut axis disease. We discuss the potential roles of 5-HT and SERT in the brain and intestinal manifestations of autism spectrum disorders and developmental antidepressant exposure. The potential therapeutic value of 5-HT 4 modulation in the subsequent treatment of these conditions is also addressed. Copyright © 2017 Elsevier B.V. All rights reserved.

Vasoactive intestinal peptide (VIP) labelling with iodine-131 by direct method; Marcacao do peptideo intestinal vasoativo (VIP) com iodo-131 por metodo direto

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Colturato, M.T.; Silva, C.P.G. da; Araujo, E.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Centro de Radiofarmacia

2002-07-01

The Vasoactive Intestinal Peptide (VIP) is a 28-amino acid polypeptide with a great numbers of receptors in tumoral cells, including adenocarcinomas and pancreatic and colon carcinomas. The VIP molecule contains two tyrosine residues, in positions 10 and 22, that are theoretically equally susceptible to iodination, The VIP was labeled with 131-iodine by direct method using Iodogen as oxidant agent: 15.03 mmol VIP + 0.10 nmol KI + [{sup 131} I]NaI + 13.9 mmol Iodogen; the final volume was adjust to 100 {mu}L using 0.2 M phosphate buffer, pH 7.5 and the reaction proceed with stirring for 30 minutes at room temperature. The radiochemical purity was determined by electrophoresis (Whatman 1MM paper; 0.05 M barbital buffer; pH 8.6; 150 V; 40 minutes) that indicates low percent of free 131-iodine. The high performance liquid chromatography (HPLC) system using RPC{sup 18}, 10 {mu}m, 4 x 250mm column, was able to separate the different radiochemical species, only when an isocratic mixture of acetonitrile: 0.1% trifluoroacetic acid (27:73) was used, with 0.5 mL/min. flux. (author)

Intestinal cholesterol secretion : future clinical implications

NARCIS (Netherlands)

Jakulj, L.; Besseling, J.; Stroes, E. S. G.; Groen, A. K.

2013-01-01

Together with the liver, the intestine serves as a homeostatic organ in cholesterol metabolism. Recent evidence has substantiated the pivotal role of the intestine in reverse cholesterol transport (RCT). RCT is a fundamental antiatherogenic pathway, mediating the removal of cholesterol from tissues

Intestinal cholesterol secretion: future clinical implications

NARCIS (Netherlands)

Jakulj, L.; Besseling, J.; Stroes, E. S. G.; Groen, A. K.

2013-01-01

Together with the liver, the intestine serves as a homeostatic organ in cholesterol metabolism. Recent evidence has substantiated the pivotal role of the intestine in reverse cholesterol transport (RCT). RCT is a fundamental antiatherogenic pathway, mediating the removal of cholesterol from tissues

The Xenobiotic Transporter Mdr1 Enforces T Cell Homeostasis in the Presence of Intestinal Bile Acids.

Science.gov (United States)

Cao, Wei; Kayama, Hisako; Chen, Mei Lan; Delmas, Amber; Sun, Amy; Kim, Sang Yong; Rangarajan, Erumbi S; McKevitt, Kelly; Beck, Amanda P; Jackson, Cody B; Crynen, Gogce; Oikonomopoulos, Angelos; Lacey, Precious N; Martinez, Gustavo J; Izard, Tina; Lorenz, Robin G; Rodriguez-Palacios, Alex; Cominelli, Fabio; Abreu, Maria T; Hommes, Daniel W; Koralov, Sergei B; Takeda, Kiyoshi; Sundrud, Mark S

2017-12-19

CD4 + T cells are tightly regulated by microbiota in the intestine, but whether intestinal T cells interface with host-derived metabolites is less clear. Here, we show that CD4 + T effector (Teff) cells upregulated the xenobiotic transporter, Mdr1, in the ileum to maintain homeostasis in the presence of bile acids. Whereas wild-type Teff cells upregulated Mdr1 in the ileum, those lacking Mdr1 displayed mucosal dysfunction and induced Crohn's disease-like ileitis following transfer into Rag1 -/- hosts. Mdr1 mitigated oxidative stress and enforced homeostasis in Teff cells exposed to conjugated bile acids (CBAs), a class of liver-derived emulsifying agents that actively circulate through the ileal mucosa. Blocking ileal CBA reabsorption in transferred Rag1 -/- mice restored Mdr1-deficient Teff cell homeostasis and attenuated ileitis. Further, a subset of ileal Crohn's disease patients displayed MDR1 loss of function. Together, these results suggest that coordinated interaction between mucosal Teff cells and CBAs in the ileum regulate intestinal immune homeostasis. Copyright © 2017 Elsevier Inc. All rights reserved.

Mechanisms of calcium transport in small intestine. Overall review of the contract, September 1, 1972--March 1, 1975

International Nuclear Information System (INIS)

DeLuca, H.F.

1975-01-01

During the past three years considerable advance has been registered in our understanding of the mechanism of intestinal calcium transport, which is activated in response to 1,25-(OH) 2 D 3 , the active form of the vitamin in the system. In brush borders isolated from vitamin D-deficient chicks, a 200,000 molecular weight protein has been found by disc gel electrophoresis which is not present in chicks given vitamin D. This protein does not bind calcium and does not possess calcium dependent adenosine triphosphatase activity. Following the administration of 1,25-(OH) 2 D 3 to the deficient chicks this protein disappears from the disc gel profiles and a protein of molecular weight 220,000 appears in the gel profiles. This protein has been isolated and shown to possess calcium adenosine triphosphatase activity, alkaline phosphatase activity and it binds calcium. Work is progressing on the purification of these proteins with the ultimate aim of discerning what role they have in intestinal calcium transport. (U.S.)

Salivaricin P, One of a Family of Two-Component Antilisterial Bacteriocins Produced by Intestinal Isolates of Lactobacillus salivarius▿

Science.gov (United States)

Barrett, Eoin; Hayes, Maria; O'Connor, Paula; Gardiner, Gillian; Fitzgerald, Gerald F.; Stanton, Catherine; Ross, R. Paul; Hill, Colin

2007-01-01

Lactobacillus salivarius DPC6005, a porcine intestinal isolate, produces a two-component bacteriocin, salivaricin P, with homology to ABP-118 produced by a human probiotic L. salivarius strain. Indeed, molecular characterization revealed that while the peptides Sln1 and ABP-118α are identical, their companion peptides (Sln2 and ABP-118β, respectively) differ by two amino acids. This observation suggests that two-component bacteriocins may be a common feature of intestinal L. salivarius strains. PMID:17416691

Phorbol esters alter adenylate cyclase responses to vasoactive intestinal peptide and forskolin in the GH cell line

Energy Technology Data Exchange (ETDEWEB)

Summers, S.; Florio, T.; Cronin, M.

1986-05-01

Activation of protein kinase C with phorbol ester modifies cyclic AMP production in several anterior pituitary cell systems. In the GH cell line from a rat pituitary tumor, exposure to phorbol 12-myristate 13-acetate (PMA: 100 nM) for 30 minutes significantly reduces vasoactive intestinal peptide (VIP: 100 nM) stimulated adenylate cyclase (AC) activity in subsequent membrane preparations to 62 + 4% of control (n = 6 independent studies). In contrast, these same membrane preparations respond to forskolin (1 ..mu..M) with significantly more activity, 130 +/- 6% of controls (n = 6 independent studies). Finally, phorbol ester does not block an inhibitory hormone input into the AC system; somatostatin (100 nM) reduction of VIP-stimulated AC activity is not significantly different in membrane preparations from PMA treated and control cells (n = 3 independent studies). These other findings lead the authors to propose that protein kinase C can modify several sites in the AC complex in anterior pituitary cells.

Identification and Relative Quantification of Bioactive Peptides Sequentially Released during Simulated Gastrointestinal Digestion of Commercial Kefir.

Science.gov (United States)

Liu, Yufang; Pischetsrieder, Monika

2017-03-08

Health-promoting effects of kefir may be partially caused by bioactive peptides. To evaluate their formation or degradation during gastrointestinal digestion, we monitored changes of the peptide profile in a model of (1) oral, (2) gastric, and (3) small intestinal digestion of kefir. Matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy analyses revealed clearly different profiles between digests 2/3 and kefir/digest 1. Subsequent ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry identified 92 peptides in total (25, 25, 43, and 30, partly overlapping in kefir and digests 1, 2, and 3, respectively), including 16 peptides with ascribed bioactivity. Relative quantification in scheduled multiple reaction monitoring mode showed that many bioactive peptides were released by simulated digestion. Most prominently, the concentration of angiotensin-converting enzyme inhibitor β-casein 203-209 increased approximately 10 000-fold after combined oral, gastric, and intestinal digestion. Thus, physiological digestive processes may promote bioactive peptide formation from proteins and oligopeptides in kefir. Furthermore, bioactive peptides present in certain compartments of the gastrointestinal tract may exert local physiological effects.

Evolutionary combinatorial chemistry, a novel tool for SAR studies on peptide transport across the blood-brain barrier. Part 2. Design, synthesis and evaluation of a first generation of peptides.

Science.gov (United States)

Teixidó, Meritxell; Belda, Ignasi; Zurita, Esther; Llorà, Xavier; Fabre, Myriam; Vilaró, Senén; Albericio, Fernando; Giralt, Ernest

2005-12-01

The use of high-throughput methods in drug discovery allows the generation and testing of a large number of compounds, but at the price of providing redundant information. Evolutionary combinatorial chemistry combines the selection and synthesis of biologically active compounds with artificial intelligence optimization methods, such as genetic algorithms (GA). Drug candidates for the treatment of central nervous system (CNS) disorders must overcome the blood-brain barrier (BBB). This paper reports a new genetic algorithm that searches for the optimal physicochemical properties for peptide transport across the blood-brain barrier. A first generation of peptides has been generated and synthesized. Due to the high content of N-methyl amino acids present in most of these peptides, their syntheses were especially challenging due to over-incorporations, deletions and DKP formations. Distinct fragmentation patterns during peptide cleavage have been identified. The first generation of peptides has been studied by evaluation techniques such as immobilized artificial membrane chromatography (IAMC), a cell-based assay, log Poctanol/water calculations, etc. Finally, a second generation has been proposed. (c) 2005 European Peptide Society and John Wiley & Sons, Ltd.

Glutamate prevents intestinal atrophy via luminal nutrient sensing in a mouse model of total parenteral nutrition

DEFF Research Database (Denmark)

Xiao, Weidong; Feng, Yongjia; Holst, Jens Juul

2014-01-01

significantly changed the amount of T1Rs, GLM receptors, and transporters, and GLM prevented these changes. GLM significantly prevented TPN-associated intestinal atrophy (2.5-fold increase in IEC proliferation) and was dependent on up-regulation of the protein kinase pAkt, but independent of T1R3 and mGluR5...... signaling. GLM led to a loss of EBF with TPN (60% increase in FITC-dextran permeability, 40% decline in transepithelial resistance); via T1R3, it protected EBF, whereas mGluR5 was associated with EBF loss. GLM led to a decline in circulating glucagon-like peptide 2 (GLP-2) during TPN. The decline...

125I-labeling and purification of peptide hormones and bovine serum albumin

International Nuclear Information System (INIS)

Nemeth, J; Jakab, B.; Szilvassy, Z.; Oroszi, G.; Roeth, E.; Magyarlaki, M.; Farkas, B.

2002-01-01

The iodination and separation of various diagnostically and/or experimentally important peptides including (Tyr 1 )-somatostatin-14, rat Tyr-α-calcitonin gene-related peptide (23-37), motilin and vasoactive intestinal peptide, furthermore bovine serum albumin are described. All species were iodinated by the iodogen method. The 125 I-labeled peptide products were separated by reversed-phase HPLC, the specific activities of mono-iodinated forms are near identical with the theoretical value. The labeled bovine serum albumin was separated by Sephadex G-100 gel filtration. (author)

Lactobacillus reuteri I5007 Modulates Intestinal Host Defense Peptide Expression in the Model of IPEC-J2 Cells and Neonatal Piglets

Science.gov (United States)

Liu, Hongbin; Hou, Chengli; Wang, Gang; Jia, Hongmin; Yu, Haitao; Zeng, Xiangfang; Thacker, Philip A.; Zhang, Guolong; Qiao, Shiyan

2017-01-01

Modulation of the synthesis of endogenous host defense peptides (HDPs) by probiotics represents a novel antimicrobial approach for disease control and prevention, particularly against antibiotic-resistant infections in human and animals. However, the extent of HDP modulation by probiotics is species dependent and strain specific. In the present study, The porcine small intestinal epithelial cell line (IPEC-J2) cells and neonatal piglets were used as in-vitro and in-vivo models to test whether Lactobacillus reuteri I5007 could modulate intestinal HDP expression. Gene expressions of HDPs, toll-like receptors, and fatty acid receptors were determined, as well as colonic short chain fatty acid concentrations and microbiota. Exposure to 108 colony forming units (CFU)/mL of L. reuteri I5007 for 6 h significantly increased the expression of porcine β-Defensin2 (PBD2), pBD3, pBD114, pBD129, and protegrins (PG) 1-5 in IPEC-J2 cells. Similarly, L. reuteri I5007 administration significantly increased the expression of jejunal pBD2 as well as colonic pBD2, pBD3, pBD114, and pBD129 in neonatal piglets (p reuteri I5007 in the piglets did not affect the colonic microbiota structure. Our findings suggested that L. reuteri I5007 could modulate intestinal HDP expression and improve the gut health of neonatal piglets, probably through the increase in colonic butyric acid concentration and the up-regulation of the downstream molecules of butyric acid, PPAR-γ and GPR41, but not through modifying gut microbiota structure. PMID:28561758

Immunohistochemical study on the ontogenetic development of the regional distribution of peptide YY, pancreatic polypeptide, and glucagon-like peptide 1 endocrine cells in bovine gastrointestinal tract.

Science.gov (United States)

Pyarokhil, Asadullah Hamid; Ishihara, Miyuki; Sasaki, Motoki; Kitamura, Nobuo

2012-04-10

The regional distribution and relative frequency of peptide YY (PYY)-, pancreatic polypeptide (PP)-, and glucagon-like peptide 1 (GLP-1)-immunoreactive (IR) cells were determined immunohistochemically in the gastrointestinal tract at seven ontogenetic stages in pre- and postnatal cattle. Different frequencies of PYY-, PP-, and GLP-1-IR cells were found in the intestines at all stages; they were not found in the esophagus and stomach. The frequencies varied depending on the intestinal segment and the developmental stage. The frequencies of PYY- and PP-IR cells were lower in the small intestine and increased from ileum to rectum, whereas GLP-1-IR cells were more numerous in duodenum and jejunum, decreased in ileum and cecum, and increased again in colon and rectum. The frequencies also varied according to pre- and postnatal stages. All three cell types were most numerous in fetus, and decreased in calf and adult groups, indicating that the frequencies of these three types of endocrine cells decrease with postnatal development. The results suggest that these changes vary depending on feeding habits and adaptation of growth, secretion, and motility of intestine at different ontogenetic stages of cattle. Copyright © 2011 Elsevier B.V. All rights reserved.

Expression and characterization of preproVIP derived peptides in the human male urogenital tract

DEFF Research Database (Denmark)

Ottesen, B; Bredkjaer, H E; Ekblad, E

1995-01-01

Expression of the gene sequence encoding vasoactive intestinal polypeptide (VIP) leads to the synthesis of a 170 amino acid precursor molecule which can be processed to five fragments: preproVIP 22-79, peptide histidine methionine (PHM), or peptide histidine valine (PHV), preproVIP 111-122, VIP...

Phosphate transport in pig proximal small intestines during postnatal development: lack of modulation by calcitriol.

Science.gov (United States)

Schröder, B; Hattenhauer, O; Breves, G

1998-04-01

the apical Pi uptake represents the major rate-limiting step of the overall transepithelial Pi transport. At weaning, Na+/Pi transport across the intestinal brush-border membrane is clearly stimulated by calcitriol, but no significant effects of age or calcitriol on the Km values (0.5-0.7 mmol/liter) were observed. In conclusion, our findings reveal calcitriol-independent mechanisms for active intestinal Pi absorption during the neonatal and suckling periods. The onset of the classical calcitriol-dependent mechanism for active intestinal Pi absorption does not occur until weaning.

Vasoactive intestinal polypeptide and peptide histidine methionine. Presence in human follicular fluid and effects on DNA synthesis and steroid secretion in cultured human granulosa/lutein cells

DEFF Research Database (Denmark)

Gräs, S; Ovesen, P; Andersen, A N

1994-01-01

Vasoactive intestinal polypeptide (VIP) and peptide histidine methionine (PHM) originate from the same precursor molecule, prepro VIP. In the present study we examined the concentrations of VIP and PHM in human follicular fluid and their effects on cultured human granulosa/lutein cells. Follicular....../l, respectively. VIP at a concentration of 10 nmol/l caused a significant increase in [3H]thymidine incorporation, and at 1000 nmol/l a significant increase in oestradiol secretion was observed. VIP had no effect on progesterone secretion. PHM at the concentrations tested did not influence any of the activities...

Neural influences on human intestinal epithelium in vitro.

Science.gov (United States)

Krueger, Dagmar; Michel, Klaus; Zeller, Florian; Demir, Ihsan E; Ceyhan, Güralp O; Slotta-Huspenina, Julia; Schemann, Michael

2016-01-15

We present the first systematic and, up to now, most comprehensive evaluation of the basic features of epithelial functions, such as basal and nerve-evoked secretion, as well as tissue resistance, in over 2200 surgical specimens of human small and large intestine. We found no evidence for impaired nerve-evoked epithelial secretion or tissue resistance with age or disease pathologies (stomach, pancreas or colon cancer, polyps, diverticulitis, stoma reversal). This indicates the validity of future studies on epithelial secretion or resistance that are based on data from a variety of surgical specimens. ACh mainly mediated nerve-evoked and basal secretion in the small intestine, whereas vasoactive intestinal peptide and nitric oxide were the primary pro-secretory transmitters in the large intestine. The results of the present study revealed novel insights into regional differences in nerve-mediated secretion in the human intestine and comprise the basis by which to more specifically target impaired epithelial functions in the diseased gut. Knowledge on basic features of epithelial functions in the human intestine is scarce. We used Ussing chamber techniques to record basal tissue resistance (R-basal) and short circuit currents (ISC; secretion) under basal conditions (ISC-basal) and after electrical field stimulation (ISC-EFS) of nerves in 2221 resectates from 435 patients. ISC-EFS was TTX-sensitive and of comparable magnitude in the small and large intestine. ISC-EFS or R-basal were not influenced by the patients' age, sex or disease pathologies (cancer, polyps, diverticulitis). Ion substitution, bumetanide or adenylate cyclase inhibition studies suggested that ISC-EFS depended on epithelial cAMP-driven chloride and bicarbonate secretion but not on amiloride-sensitive sodium absorption. Although atropine-sensitive cholinergic components prevailed for ISC-EFS of the duodenum, jejunum and ileum, PG97-269-sensitive [vasoactive intestinal peptide (VIP) receptor 1

Peptides reproducibly released by in vivo digestion of beef meat and trout flesh in pigs.

Science.gov (United States)

Bauchart, Caroline; Morzel, Martine; Chambon, Christophe; Mirand, Philippe Patureau; Reynès, Christelle; Buffière, Caroline; Rémond, Didier

2007-12-01

Characterisation and identification of peptides (800 to 5000 Da) generated by intestinal digestion of fish or meat were performed using MS analyses (matrix-assisted laser desorption ionisation time of flight and nano-liquid chromatography electrospray-ionisation ion trap MS/MS). Four pigs fitted with cannulas at the duodenum and jejunum received a meal exclusively made of cooked Pectoralis profundus beef meat or cooked trout fillets. A protein-free meal, made of free amino acids, starch and fat, was used to identify peptides of endogenous origin. Peptides reproducibly detected in digesta (i.e. from at least three pigs) were evidenced predominantly in the first 3 h after the meal. In the duodenum, most of the fish- and meat-derived peptides were characteristic of a peptic digestion. In the jejunum, the majority of peptides appeared to result from digestion by chymotrypsin and trypsin. Despite slight differences in gastric emptying kinetics and overall peptide production, possibly in relation to food structure and texture, six and four similar peptides were released after ingestion of fish or meat in the duodenum and jejunum. A total of twenty-six different peptides were identified in digesta. All were fragments of major structural (actin, myosin) or sarcoplasmic (creatine kinase, glyceraldehyde-3-phosphate dehydrogenase and myoglobin) muscle proteins. Peptides were short ( digestion, some of them can be reproducibly observed in intestinal digesta.

Tumor penetrating peptides

Directory of Open Access Journals (Sweden)

Tambet eTeesalu

2013-08-01

Full Text Available Tumor-homing peptides can be used to deliver drugs into tumors. Phage library screening in live mice has recently identified homing peptides that specifically recognize the endothelium of tumor vessels, extravasate, and penetrate deep into the extravascular tumor tissue. The prototypic peptide of this class, iRGD (CRGDKGPDC, contains the integrin-binding RGD motif. RGD mediates tumor homing through binding to αv integrins, which are selectively expressed on various cells in tumors, including tumor endothelial cells. The tumor-penetrating properties of iRGD are mediated by a second sequence motif, R/KXXR/K. This C-end Rule (or CendR motif is active only when the second basic residue is exposed at the C-terminus of the peptide. Proteolytic processing of iRGD in tumors activates the cryptic CendR motif, which then binds to neuropilin-1 activating an endocytic bulk transport pathway through tumor tissue. Phage screening has also yielded tumor-penetrating peptides that function like iRGD in activating the CendR pathway, but bind to a different primary receptor. Moreover, novel tumor-homing peptides can be constructed from tumor-homing motifs, CendR elements and protease cleavage sites. Pathologies other than tumors can be targeted with tissue-penetrating peptides, and the primary receptor can also be a vascular zip code of a normal tissue. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. The tumor-penetrating peptides are capable of taking a payload deep into tumor tissue in mice, and they also penetrate into human tumors ex vivo. Targeting with these peptides specifically increases the accumulation in tumors of a variety of drugs and contrast agents, such as doxorubicin, antibodies and nanoparticle-based compounds. Remarkably the drug to be targeted does not have to be coupled to the peptide; the bulk transport system activated by the peptide sweeps along any compound that is

Computational Studies of Drug Release, Transport and Absorption in the Human Intestines

Science.gov (United States)

Behafarid, Farhad; Brasseur, J. G.; Vijayakumar, G.; Jayaraman, B.; Wang, Y.

2016-11-01

Following disintegration of a drug tablet, a cloud of particles 10-200 μm in diameter enters the small intestine where drug molecules are absorbed into the blood. Drug release rate depends on particle size, solubility and hydrodynamic enhancements driven by gut motility. To quantify the interrelationships among dissolution, transport and wall permeability, we apply lattice Boltzmann method to simulate the drug concentration field in the 3D gut released from polydisperse distributions of drug particles in the "fasting" vs. "fed" motility states. Generalized boundary conditions allow for both solubility and gut wall permeability to be systematically varied. We apply a local 'quasi-steady state' approximation for drug dissolution using a mathematical model generalized for hydrodynamic enhancements and heterogeneity in drug release rate. We observe fundamental differences resulting from the interplay among release, transport and absorption in relationship to particle size distribution, luminal volume, motility, solubility and permeability. For example, whereas smaller volume encourages higher bulk concentrations and reduced release rate, it also encourages higher absorption rate, making it difficult to generalize predictions. Supported by FDA.

Targeting nanoparticles to M cells with non-peptidic ligands for oral vaccination

OpenAIRE

Fievez, Virginie; Plapied, Laurence; des Rieux, Anne; Pourcelle, Vincent; Freichels, Hélène; Wascotte, Valentine; Vanderhaegen, Marie-Lyse; Jérôme, Christine; Vanderplasschen, Alain; Marchand-Brynaert, Jacqueline; Préat, Véronique

2009-01-01

The presence of RGD on nanoparticles allows the targeting of β1 integrins at the apical surface of human M cells and the enhancement of an immune response after oral immunization. To check the hypothesis that non-peptidic ligands targeting intestinal M cells or APCs would be more efficient for oral immunization than RGD, novel non-peptidic and peptidic analogs (RGD peptidomimitic (RGDp), LDV derivative (LDVd) and LDV peptidomimetic (LDVp)) as well as mannose were grafted on the PEG chain of P...

Immunoglobulin G antibodies against deamidated-gliadin-peptides outperform anti-endomysium and tissue transglutaminase antibodies in children

NARCIS (Netherlands)

Mubarak, A.; Gmelig-Meyling, F. H. J.; Wolters, V. M.; ten Kate, F. J. W.; Houwen, R. H. J.

2011-01-01

To investigate the usefulness of deamidated-gliadin-peptides-antibodies in the diagnosis of celiac disease, serology was tested in 212 children suspected with celiac disease who had undergone a small-intestinal-biopsy. For deamidated-gliadin-peptides-antibodies, two kits were tested. Positive and

Plasma levels of gastrointestinal regulatory peptides in patients receiving maintenance hemodialysis

International Nuclear Information System (INIS)

Hegbrant, J.; Thysell, H.; Ekmann, R.

1991-01-01

The fasting plasma levels of nine gastrointestinal regulatory peptides were measured by radioimmunoassay in 13 stable patients with chronic renal failure, receiving hemodialysis treatment regularly and compared with those of ten healthy controls. The plasma concentrations of gastrin-releasing peptide, motilin, neurotensin, pancreatic polypeptide, peptide YY, somatostatin, substance P, and vasoactive intestinal peptide were increased. The plasma level of gastrin was not statistically different from that of the control (p=0.077). It is concluded that patients with chronic renal failure, receiving hemodialysis treatment regularly, have increased concentrations of eight of nine measured gastrointestinal regulatory peptides. The elevated levels of gastrointestinal peptides in patients with chronic renal failure may contribute to uremic gastrointestinal symptoms and dysfunctions. It is necessary to make a renal function evaluation before interpreting measured plasma levels of gastrointestinal regulatory peptides. 62 refs., 2 tabs

Use of LDL receptor-targeting peptide vectors for in vitro and in vivo cargo transport across the blood-brain barrier.

Science.gov (United States)

Molino, Yves; David, Marion; Varini, Karine; Jabès, Françoise; Gaudin, Nicolas; Fortoul, Aude; Bakloul, Karima; Masse, Maxime; Bernard, Anne; Drobecq, Lucile; Lécorché, Pascaline; Temsamani, Jamal; Jacquot, Guillaume; Khrestchatisky, Michel

2017-05-01

The blood-brain barrier (BBB) prevents the entry of many drugs into the brain and, thus, is a major obstacle in the treatment of CNS diseases. There is some evidence that the LDL receptor (LDLR) is expressed at the BBB and may participate in the transport of endogenous ligands from blood to brain, a process referred to as receptor-mediated transcytosis. We previously described a family of peptide vectors that were developed to target the LDLR. In the present study, in vitro BBB models that were derived from wild-type and LDLR-knockout animals ( ldlr -/- ) were used to validate the specific LDLR-dependent transcytosis of LDL via a nondegradative route. We next showed that LDLR-targeting peptide vectors, whether in fusion or chemically conjugated to an Ab Fc fragment, promote binding to apical LDLR and transendothelial transfer of the Fc fragment across BBB monolayers via the same route as LDL. Finally, we demonstrated in vivo that LDLR significantly contributes to the brain uptake of vectorized Fc. We thus provide further evidence that LDLR is a relevant receptor for CNS drug delivery via receptor-mediated transcytosis and that the peptide vectors we developed have the potential to transport drugs, including proteins or Ab based, across the BBB.-Molino, Y., David, M., Varini, K., Jabès, F., Gaudin, N., Fortoul, A., Bakloul, K., Masse, M., Bernard, A., Drobecq, L., Lécorché, P., Temsamani, J., Jacquot, G., Khrestchatisky, M. Use of LDL receptor-targeting peptide vectors for in vitro and in vivo cargo transport across the blood-brain barrier. © FASEB.

Molecular characterization of covalent complexes between tissue transglutaminase and gliadin peptides

DEFF Research Database (Denmark)

Fleckenstein, Burkhard; Qiao, Shuo-Wang; Larsen, Martin Røssel

2004-01-01

recognized by intestinal T cells from patients. Incubation of TG2 with gliadin peptides also results in the formation of covalent TG2-peptide complexes. Here we report the characterization of complexes between TG2 and two immunodominant gliadin peptides. Two types of covalent complexes were found......; the peptides are either linked via a thioester bond to the active site cysteine of TG2 or via isopeptide bonds to particular lysine residues of the enzyme. We quantified the number of gliadin peptides bound to TG2 under different conditions. After 30 min of incubation of TG2 at 1 microm with an equimolar ratio...... of peptides to TG2, approximately equal amounts of peptides were bound by thioester and isopeptide linkage. At higher peptide to TG2 ratios, more than one peptide was linked to TG2, and isopeptide bond formation dominated. The lysine residues in TG2 that act as acyl acceptors were identified by matrix...

Effects of semielemental diet containing whey peptides on Peyer's patch lymphocyte number, immunoglobulin A levels, and intestinal morphology in mice.

Science.gov (United States)

Moriya, Tomoyuki; Fukatsu, Kazuhiko; Noguchi, Midori; Nishikawa, Makoto; Miyazaki, Hiromi; Saitoh, Daizoh; Ueno, Hideki; Yamamoto, Junji

2018-02-01

Enteral nutrition (EN) is the gold standard of nutritional therapy for critically ill or severely injured patients, because EN promotes gut and hepatic immunity, thereby preventing infectious complications as compared with parenteral nutrition. However, there are many EN formulas with different protein and fat contents. Their effects on gut-associated lymphoid tissue remain unclear. Recently, semielemental diets (SEDs) containing whey peptides as a nitrogen source have been found to be beneficial in patients with malabsorption or pancreatitis. Herein, we examined the influences of various dietary formulations on gut immunity to clarify the advantages of SEDs over elemental diets. Forty-four male Institute of Cancer Research mice were randomized to four groups: chow (CH: n = 5), intragastric total parenteral nutrition (IG-TPN: n = 13), elemental diet (ED: n = 13), and SED (n = 13). The CH group received CH diet ad libitum, whereas the IG-TPN, ED (Elental, Ajinomoto, Japan), and SED (Peptino, Terumo, Japan) groups were given their respective diets for 5 day via gastrostomy. After 5 days, the mice were killed to obtain whole small intestines. Peyer's patch (PP) lymphocytes were harvested and counted. Their subpopulations were evaluated by flow cytometry. Immunoglobulin A (IgA) levels in intestinal and respiratory tract washings were measured with enzyme-linked immunosorbent assay. Villous height (VH) and crypt depth in the distal intestine were measured by light microscopy. SED increased the PP cell number and intestinal or respiratory IgA levels to those of CH mice, while ED partially restored these parameters. The IG-TPN group showed the lowest PP cell number and IgA levels among the four groups. VH was significantly greater in the CH than in the other groups. VH in the ED and SED groups also exceeded in the IG-TPN group, while being similar in these two groups. No significant crypt depth differences were observed among the four groups. SED administration

Novel Peptide with Specific Calcium-Binding Capacity from Schizochytrium sp. Protein Hydrolysates and Calcium Bioavailability in Caco-2 Cells

Directory of Open Access Journals (Sweden)

Xixi Cai

2016-12-01

Full Text Available Peptide-calcium can probably be a suitable supplement to improve calcium absorption in the human body. In this study, a specific peptide Phe-Tyr (FY with calcium-binding capacity was purified from Schizochytrium sp. protein hydrolysates through gel filtration chromatography and reversed phase HPLC. The calcium-binding capacity of FY reached 128.77 ± 2.57 μg/mg. Results of ultraviolet spectroscopy, fluorescence spectroscopy, and infrared spectroscopy showed that carboxyl groups, amino groups, and amido groups were the major chelating sites. FY-Ca exhibited excellent thermal stability and solubility, which were beneficial to be absorbed and transported in the basic intestinal tract of the human body. Moreover, the calcium bioavailability in Caco-2 cells showed that FY-Ca could enhance calcium uptake efficiency by more than three times when compared with CaCl2, and protect calcium ions against dietary inhibitors, such as tannic acid, oxalate, phytate, and Zn2+. Our findings further the progress of algae-based peptide-calcium, suggesting that FY-Ca has the potential to be developed as functionally nutraceutical additives.

Epidermal growth factor inhibits glycylsarcosine transport and hPepT1 expression in a human intestinal cell line

DEFF Research Database (Denmark)

Nielsen, C U; Amstrup, J; Steffansen, B

2001-01-01

(max) decreased from 2.61 +/- 0.4 to 1.06 +/- 0.1 nmol x cm(-2) x min(-1) (n = 3, P PepT1 mRNA (using glucose-6-phosphate dehydrogenase mRNA as control......) in cells treated with EGF. Western blotting indicated a decrease in hPepT1 protein in cell lysates. We conclude that EGF treatment decreases Gly-Sar transport in Caco-2 cells by decreasing the number of peptide transporter molecules in the apical membrane....

Lateralized hippocampal effects of vasoactive intestinal peptide on learning and memory in rats in a model of depression.

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Ivanova, Margarita; Belcheva, Stiliana; Belcheva, Iren; Negrev, Negrin; Tashev, Roman

2012-06-01

Findings of pharmacological studies revealed that vasoactive intestinal peptide (VIP) plays a modulatory role in learning and memory. A role of the peptide in the neurobiological mechanisms of affective disorders was also suggested. The objectives are to study the involvement of VIP in learning and memory processes after unilateral and bilateral local application into hippocampal CA1 area in rats with a model of depression (bilateral olfactory bulbectomy--OBX) and to test whether VIP receptors could affect cognition. VIP (50 ng) and combination (VIP(6-28) 10 ng + VIP 50 ng) microinjected bilaterally or into the right CA1 area improved the learning and memory of OBX rats in shuttle-box and step-through behavioral tests as compared to the saline-treated OBX controls. Left-side VIP microinjections did not affect the number of avoidances (shuttle box) and learning criteria (step through) as compared to the left-side saline-treated OBX controls. The administration of the combination into left CA1 influenced positively the performance in the step-through task. VIP antagonist (VIP(6-28), 10 ng) did not affect learning and memory of OBX rats. These findings suggest asymmetric effect of VIP on cognitive processes in hippocampus of rats with OBX model of depression. Our results point to a lateralized modulatory effect of VIP injected in the hippocampal CA1 area on the avoidance deficits in OBX rats. The right CA1 area was predominantly involved in the positive effect of VIP on learning and memory. A possible role of the PAC1 receptors is suggested.

Mathematical Modeling of Interacting Glucose-Sensing Mechanisms and Electrical Activity Underlying Glucagon-Like Peptide 1 Secretion.

Directory of Open Access Journals (Sweden)

Michela Riz

2015-12-01

Full Text Available Intestinal L-cells sense glucose and other nutrients, and in response release glucagon-like peptide 1 (GLP-1, peptide YY and other hormones with anti-diabetic and weight-reducing effects. The stimulus-secretion pathway in L-cells is still poorly understood, although it is known that GLP-1 secreting cells use sodium-glucose co-transporters (SGLT and ATP-sensitive K+-channels (K(ATP-channels to sense intestinal glucose levels. Electrical activity then transduces glucose sensing to Ca2+-stimulated exocytosis. This particular glucose-sensing arrangement with glucose triggering both a depolarizing SGLT current as well as leading to closure of the hyperpolarizing K(ATP current is of more general interest for our understanding of glucose-sensing cells. To dissect the interactions of these two glucose-sensing mechanisms, we build a mathematical model of electrical activity underlying GLP-1 secretion. Two sets of model parameters are presented: one set represents primary mouse colonic L-cells; the other set is based on data from the GLP-1 secreting GLUTag cell line. The model is then used to obtain insight into the differences in glucose-sensing between primary L-cells and GLUTag cells. Our results illuminate how the two glucose-sensing mechanisms interact, and suggest that the depolarizing effect of SGLT currents is modulated by K(ATP-channel activity. Based on our simulations, we propose that primary L-cells encode the glucose signal as changes in action potential amplitude, whereas GLUTag cells rely mainly on frequency modulation. The model should be useful for further basic, pharmacological and theoretical investigations of the cellular signals underlying endogenous GLP-1 and peptide YY release.

Prodrugs of purine and pyrimidine analogues for the intestinal di/tri-peptide transporter PepT1

DEFF Research Database (Denmark)

Thomsen, Anne Engelbrecht; Friedrichsen, Gerda Marie; Sørensen, Arne Hagsten

2003-01-01

, novel L-Glu-Sar and D-Glu-Ala ester prodrugs of acyclovir and 1-(2-hydroxyethyl)-linked thymine were synthesized and their affinities for hPepT1 in Caco-2 cells were determined. Furthermore, the degradation of the prodrugs was investigated in various aqueous and biological media and compared...... to the corresponding hydrolysis of the prodrug valaciclovir. Affinity studies showed that the L-Glu-Sar prodrugs had high affinity for hPepT1 (K(i) approximately 0.2-0.3 mM), whereas the D-Glu-Ala prodrugs had poor affinity (K(i) approximately 50 mM). The pH-rate profiles of the prodrugs D-Glu[1-(2-hydroxyethyl......)thymine]-Ala and L-Glu[acyclovir]-Sar showed specific base catalyzed degradation at pH above 4.5 and 5.5, respectively. This implicates that the degradation rates at pH approximately 7.4 (t(1/2) approximately 3.5 and 5.5 h) are approximately 25 times faster than at upper small intestinal pH approximately 6.0. In 10...

Modulation of small intestinal phosphate transporter by dietary supplements of mineral phosphorus and phytase in broilers.

Science.gov (United States)

Huber, Korinna; Zeller, Ellen; Rodehutscord, Markus

2015-05-01

Dietary phosphorus (P) is known as a main modulator of phosphate (Pi) transporter expression. The effect of supplemented mineral P with or without phytase on protein expression of two sodium-dependent Pi (NaPi) transporters and a calcium channel was studied in the small intestine of broilers. Thirty-six broilers were randomly assigned to six different diets at 15 days of age. Two levels of total P (tP, adjusted by monocalcium phosphate (MCP) supplementation), 0.39% (BD-) and 0.47% (BD+) were fed until day 25; and at each tP level, three levels of phytase were used with 0, 500, and 12,500 FTU/kg of an E. coli phytase. Mucosa samples from jejunum and ileum were taken and apical membranes were isolated by MgCl2 precipitation. Protein expression of NaPi IIb, NaPi type III (PiT1) and the calcium channel TRPV6 were semiquantitatively measured by Western blotting and jejunal mucosal phytase activity by measurement of Pi release. The jejunal NaPi IIb transporter was expressed with two distinct bands, which were modulated differently by diet. NaPi IIb Band1 increased (P phytase supplementation but was not affected by MCP supplementation. This inverse modulation of Band1 and Band2 was significantly related to the amount of net absorbed P with higher expression of Band1 at higher amounts of net absorbed P. In addition, a second Pi transporter, PiT1, was detected in which ileal expression decreased (P phytase supplementation. The expression of the calcium channel TRPV6 was increased in BD+ groups. A trend for an interaction between MCP and phytase supplementation on mucosal phytase activity was observed (P = 0.079) with a decrease in activity when BD+ with 12,500 FTU/kg phytase was fed. Chicken intestinal epithelial cells responded to dietary supplemented phytase and MCP by changing the Pi transporter expression in apical membranes. In conclusion, availability of Pi is most likely the key modulator of transporter protein expression. However, a contribution of lower inositol

Human mini-guts: new insights into intestinal physiology and host-pathogen interactions.

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In, Julie G; Foulke-Abel, Jennifer; Estes, Mary K; Zachos, Nicholas C; Kovbasnjuk, Olga; Donowitz, Mark

2016-11-01

The development of indefinitely propagating human 'mini-guts' has led to a rapid advance in gastrointestinal research related to transport physiology, developmental biology, pharmacology, and pathophysiology. These mini-guts, also called enteroids or colonoids, are derived from LGR5 + intestinal stem cells isolated from the small intestine or colon. Addition of WNT3A and other growth factors promotes stemness and results in viable, physiologically functional human intestinal or colonic cultures that develop a crypt-villus axis and can be differentiated into all intestinal epithelial cell types. The success of research using human enteroids has highlighted the limitations of using animals or in vitro, cancer-derived cell lines to model transport physiology and pathophysiology. For example, curative or preventive therapies for acute enteric infections have been limited, mostly due to the lack of a physiological human intestinal model. However, the human enteroid model enables specific functional studies of secretion and absorption in each intestinal segment as well as observations of the earliest molecular events that occur during enteric infections. This Review describes studies characterizing these human mini-guts as a physiological model to investigate intestinal transport and host-pathogen interactions.

Lactobacillus GG and tributyrin supplementation reduce antibiotic-induced intestinal injury.

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Cresci, Gail; Nagy, Laura E; Ganapathy, Vadivel

2013-11-01

Antibiotic therapy negatively alters the gut microbiota. Lactobacillus GG (LGG) decreases antibiotic-associated diarrhea (AAD) symptoms, but the mechanisms are unknown. Butyrate has beneficial effects on gut health. Altered intestinal gene expression occurs in the absence of gut microbiota. We hypothesized that antibiotic-induced changes in gut microbiota reduce butyrate production, varying genes involved with gut barrier integrity and water and electrolyte absorption, lending to AAD, and that simultaneous supplementation with LGG and/or tributyrin would prevent these changes. C57BL/6 mice aged 6-8 weeks received a chow diet while divided into 8 treatment groups (± saline, ± LGG, ± tributyrin, or both). Mice received treatments orally for 7 days with ± broad-spectrum antibiotics. Water intake was recorded daily and body weight was measured. Intestine tissue samples were obtained and analyzed for expression of genes and proteins involved with water and electrolyte absorption, butyrate transport, and gut integrity via polymerase chain reaction and immunohistochemistry. Antibiotics decreased messenger RNA (mRNA) expression (butyrate transporter and receptor, Na(+)/H(+) exchanger, Cl(-)/HCO3 (-), and a water channel) and protein expression (butyrate transporter, Na(+)/H(+) exchanger, and tight junction proteins) in the intestinal tract. LGG and/or tributyrin supplementation maintained intestinal mRNA expression to that of the control animals, and tributyrin maintained intestinal protein intensity expression to that of control animals. Broad-spectrum antibiotics decrease expression of anion exchangers, butyrate transporter and receptor, and tight junction proteins in mouse intestine. Simultaneous oral supplementation with LGG and/or tributyrin minimizes these losses. Optimizing intestinal health with LGG and/or tributyrin may offer a preventative therapy for AAD.

Proteomic analysis of rainbow trout (Oncorhynchus mykiss) intestinal epithelia: physiological acclimation to short-term starvation.

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Baumgarner, Bradley L; Bharadwaj, Anant S; Inerowicz, Dorota; Goodman, Angela S; Brown, Paul B

2013-03-01

The intestinal epithelia form the first line of defense against harmful agents in the gut lumen of most monogastric vertebrates, including teleost fishes. Previous investigations into the effect of starvation on the intestinal epithelia of teleost fishes have focused primarily on changes in morphological characteristics and targeted molecular analysis of specific enzymes. The goal of this study was to use a comprehensive approach to help reveal how the intestinal epithelia of carnivorous teleost fishes acclimate to short-term nutrient deprivation. We utilized two-dimensional gel electrophoresis (2-DE) to conduct the proteomic analysis of the mucosal and epithelial layer of the anterior gut intestinal tract (GIT) from satiation fed vs. 4 week starved rainbow trout (Oncorhynchus mykiss). A total of 40 proteins were determined to be differentially expressed and were subsequently picked for in-gel trypsin digestion. Peptide mass fingerprint analysis was conducted using matrix assisted laser desorption time-of-flight/time-of-flight. Nine of the 11 positively identified proteins were directly related to innate immunity. The expression of α-1 proteinase inhibitor decreased in starved vs. fed fish. Also, the concentration of one leukocyte elastase inhibitor (LEI) isomer decreased in starved fish, though the concentration of another LEI isomer increased in due to starvation. In addition, starvation promoted an increased concentration of the important xenobiotic-transporter p-glycoprotein. Finally, starvation resulted in a significant increase in type II keratin E2. Overall, our results indicate that starvation promoted a reduced capacity to inhibit enzymatic stress but increased xenobiotic resistance and paracellular permeability of epithelial cells in the anterior intestine of rainbow trout. Copyright © 2012 Elsevier Inc. All rights reserved.

Short communication: Promotion of glucagon-like peptide-2 secretion in dairy calves with a bioactive extract from Olea europaea.

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Morrison, S Y; Pastor, J J; Quintela, J C; Holst, J J; Hartmann, B; Drackley, J K; Ipharraguerre, I R

2017-03-01

Diarrhea episodes in dairy calves involve profound alterations in the mechanism controlling gut barrier function that ultimately compromise intestinal permeability to macromolecules, including pathogenic bacteria. Intestinal dysfunction models suggest that a key element of intestinal adaptation during the neonatal phase is the nutrient-induced secretion of glucagon-like peptide (GLP)-2 and associated effects on mucosal cell proliferation, barrier function, and inflammatory response. Bioactive molecules found in Olea europaea have been shown to induce the release of regulatory peptides from model enteroendocrine cells. The ability to enhance GLP-2 secretion via the feeding of putative GLP-2 secretagogues is untested in newborn calves. The objectives of this study were to determine whether feeding a bioactive extract from Olea europaea (OBE) mixed in the milk replacer (1) can stimulate GLP-2 secretion beyond the response elicited by enteral nutrients and, thereby, (2) improve intestinal permeability and animal growth as well as (3) reduce the incidence of diarrhea in preweaning dairy calves. Holstein heifer calves (n = 60) were purchased, transported to the research facility, and blocked by body weight and total serum protein and assigned to 1 of 3 treatments. Treatments were control (CON), standard milk replacer (MR) and ad libitum starter; CON plus OBE added into MR at 30 mg/kg of body weight (OBE30); and CON plus OBE added into MR at 60 mg/kg of body weight (OBE60). The concentration of GLP-2 was measured at the end of wk 2. Intestinal permeability was measured at the onset of the study and the end of wk 2 and 6, with lactulose and d-mannitol as markers. Treatments did not affect calf growth and starter intake. Compared with CON, administration of OBE60 increased the nutrient-induced response in GLP-2 by about 1 fold and reduced MR intake during the second week of study. Throughout the study, however, all calves had compromised intestinal permeability and a high

Orexins control intestinal glucose transport by distinct neuronal, endocrine, and direct epithelial pathways.

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Ducroc, Robert; Voisin, Thierry; El Firar, Aadil; Laburthe, Marc

2007-10-01

Orexins are neuropeptides involved in energy homeostasis. We investigated the effect of orexin A (OxA) and orexin B (OxB) on intestinal glucose transport in the rat. Injection of orexins led to a decrease in the blood glucose level in oral glucose tolerance tests (OGTTs). Effects of orexins on glucose entry were analyzed in Ussing chambers using the Na(+)-dependent increase in short-circuit current (Isc) to quantify jejunal glucose transport. The rapid and marked increase in Isc induced by luminal glucose was inhibited by 10 nmol/l OxA or OxB (53 and 59%, respectively). Response curves to OxA and OxB were not significantly different with half-maximal inhibitory concentrations at 0.9 and 0.4 nmol/l, respectively. On the one hand, OxA-induced inhibition of Isc was reduced by the neuronal blocker tetrodotoxin (TTX) and by a cholecystokinin (CCK) 2R antagonist, indicating involvement of neuronal and endocrine CCK-releasing cells. The OX(1)R antagonist SB334867 had no effect on OxA-induced inhibition, which is likely to occur via a neuronal and/or endocrine OX(2)R. On the other hand, SB334867 induced a significant right shift of the concentration-effect curve for OxB. This OxB-preferring OX(1)R pathway was not sensitive to TTX or to CCKR antagonists, suggesting that OxB may act directly on enterocytic OX(1)R. These distinct effects of OxA and OxB are consistent with the expression of OX(1)R and OX(2)R mRNA in the epithelial and nonepithelial tissues, respectively. Our data delineate a new function for orexins as inhibitors of intestinal glucose absorption and provide a new basis for orexin-induced short-term control of energy homeostasis.

Escherichia coli Peptide Binding Protein OppA Has a Preference for Positively Charged Peptides

NARCIS (Netherlands)

Klepsch, M. M.; Kovermann, M.; Löw, C.; Balbach, J.; Permentier, H. P.; Fusetti, F.; de Gier, J. W.; Gier, Jan-Willem de; Slotboom, D. J.; Berntsson, R. P. -A.

2011-01-01

The Escherichia coli peptide binding protein OppA is an essential component of the oligopeptide transporter Opp. Based on studies on its orthologue from Salmonella typhimurium, it has been proposed that OppA binds peptides between two and five amino acids long, with no apparent sequence selectivity.

Plasma endocannabinoid levels in lean, overweight and obese humans: relationships with intestinal permeability markers, inflammation and incretin secretion.

Science.gov (United States)

Little, Tanya J; Cvijanovic, Nada; DiPatrizio, Nicholas V; Argueta, Donovan A; Rayner, Christopher K; Feinle-Bisset, Christine; Young, Richard L

2018-02-13

Intestinal production of endocannabinoid and oleoylethanolamide (OEA) is impaired in high-fat diet/obese rodents, leading to reduced satiety. Such diets also alter the intestinal microbiome in association with enhanced intestinal permeability and inflammation, however little is known of these effects in humans. This study aimed to: (i) evaluate effects of lipid on plasma anandamide (AEA), 2-arachidonyl-sn-glycerol (2-AG) and OEA in humans, and (ii) examine relationships with intestinal permeability, inflammation markers and incretin hormone secretion. 20 lean, 18 overweight and 19 obese participants underwent intraduodenal Intralipid® infusion (2 kcal/min) with collection of endoscopic duodenal biopsies and blood. Plasma AEA, 2-AG, and OEA (HPLC/tandem mass spectrometry), tumour necrosis factor-α (TNF-α), glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) (multiplex), and duodenal expression of occludin, zona-occludin-1 (ZO-1), intestinal-alkaline-phosphatase (IAP), and toll-like receptor-4 (TLR4) (RT-PCR), were assessed. Fasting plasma AEA was increased in obese, compared with lean and overweight (Plean (Plean and overweight. The relationships between plasma AEA with duodenal ZO-1 and IAP, and GIP, suggest that altered endocannabinoid signalling may contribute to changes in intestinal permeability, inflammation and incretin release in human obesity.

Mechanisms of Intestinal Serotonin Transporter (SERT Upregulation by TGF-β1 Induced Non-Smad Pathways.

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Saad Nazir

Full Text Available TGF-β1 is an important multifunctional cytokine with numerous protective effects on intestinal mucosa. The influence of TGF-β1 on serotonin transporter (SERT activity, the critical mechanism regulating the extracellular availability of serotonin (5-HT, is not known. Current studies were designed to examine acute effects of TGF-β1 on SERT. Model human intestinal Caco-2 cells grown as monolayer's or as cysts in 3D culture and ex vivo mouse model were utilized. Treatment of Caco-2 cells with TGF-β1 (10 ng/ml, 60 min stimulated SERT activity (~2 fold, P<0.005. This stimulation of SERT function was dependent upon activation of TGF-β1 receptor (TGFRI as SB-431542, a specific TGF-βRI inhibitor blocked the SERT stimulation. SERT activation in response to TGF-β1 was attenuated by inhibition of PI3K and occurred via enhanced recruitment of SERT-GFP to apical surface in a PI3K dependent manner. The exocytosis inhibitor brefeldin A (2.5 μM attenuated the TGF-β1-mediated increase in SERT function. TGF-β1 increased the association of SERT with the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE syntaxin 3 (STX3 and promoted exocytosis of SERT. Caco-2 cells grown as cysts in 3D culture recapitulated the effects of TGF-β1 showing increased luminal staining of SERT. Ussing chamber studies revealed increase in 3H-5-HT uptake in mouse ileum treated ex vivo with TGF-β1 (10 ng/ml, 1h. These data demonstrate a novel mechanism rapidly regulating intestinal SERT via PI3K and STX3. Since decreased SERT is implicated in various gastro-intestinal disorders e.g IBD, IBS and diarrhea, understanding mechanisms stimulating SERT function by TGF-β1 offers a novel therapeutic strategy to treat GI disorders.

Safety concerns over the use of intestinal permeation enhancers: A mini-review.

Science.gov (United States)

McCartney, Fiona; Gleeson, John P; Brayden, David J

2016-01-01

Intestinal permeation enhancers (PEs) are key components in ∼12 oral peptide formulations in clinical trials for a range of molecules, primarily insulin and glucagon-like-peptide 1 (GLP-1) analogs. The main PEs comprise medium chain fatty acid-based systems (sodium caprate, sodium caprylate, and N-[8-(2-hydroxybenzoyl) amino] caprylate (SNAC)), bile salts, acyl carnitines, and EDTA. Their mechanism of action is complex with subtle differences between the different molecules. With the exception of SNAC and EDTA, most PEs fluidize the plasma membrane causing plasma membrane perturbation, as well as enzymatic and intracellular mediator changes that lead to alteration of intestinal epithelial tight junction protein expression. The question arises as to whether PEs can cause irreversible epithelial damage and tight junction openings sufficient to permit co-absorption of payloads with bystander pathogens, lipopolysaccharides and its fragment, or exo- and endotoxins that may be associated with sepsis, inflammation and autoimmune conditions. Most PEs seem to cause membrane perturbation to varying extents that is rapidly reversible, and overall evidence of pathogen co-absorption is generally lacking. It is unknown however, whether the intestinal epithelial damage-repair cycle is sustained during repeat-dosing regimens for chronic therapy.

Expression of Na+/glucose co-transporter 1 (SGLT1) is enhanced by supplementation of the diet of weaning piglets with artificial sweeteners.

Science.gov (United States)

Moran, Andrew W; Al-Rammahi, Miran A; Arora, Daleep K; Batchelor, Daniel J; Coulter, Erin A; Daly, Kristian; Ionescu, Catherine; Bravo, David; Shirazi-Beechey, Soraya P

2010-09-01

In an intensive livestock production, a shorter suckling period allows more piglets to be born. However, this practice leads to a number of disorders including nutrient malabsorption, resulting in diarrhoea, malnutrition and dehydration. A number of strategies have been proposed to overcome weaning problems. Artificial sweeteners, routinely included in piglets' diet, were thought to enhance feed palatability. However, it is shown in rodent models that when included in the diet, they enhance the expression of Na+/glucose co-transporter (SGLT1) and the capacity of the gut to absorb glucose. Here, we show that supplementation of piglets' feed with a combination of artificial sweeteners saccharin and neohesperidin dihydrochalcone enhances the expression of SGLT1 and intestinal glucose transport function. Artificial sweeteners are known to act on the intestinal sweet taste receptor T1R2/T1R3 and its partner G-protein, gustducin, to activate pathways leading to SGLT1 up-regulation. Here, we demonstrate that T1R2, T1R3 and gustducin are expressed together in the enteroendocrine cells of piglet intestine. Furthermore, gut hormones secreted by the endocrine cells in response to dietary carbohydrates, glucagon-like peptides (GLP)-1, GLP-2 and glucose-dependent insulinotrophic peptide (GIP), are co-expressed with type 1 G-protein-coupled receptors (T1R) and gustducin, indicating that L- and K-enteroendocrine cells express these taste elements. In a fewer endocrine cells, T1R are also co-expressed with serotonin. Lactisole, an inhibitor of human T1R3, had no inhibitory effect on sweetener-induced SGLT1 up-regulation in piglet intestine. A better understanding of the mechanism(s) involved in sweetener up-regulation of SGLT1 will allow the identification of nutritional targets with implications for the prevention of weaning-related malabsorption.

Neural regulation of glucagon-like peptide-1 secretion in pigs

DEFF Research Database (Denmark)

Hansen, Lene; Lampert, Sarah; Mineo, Hitoshi

2004-01-01

Glucagon-like peptide (GLP)-1 is secreted rapidly from the intestine postprandially. We therefore investigated its possible neural regulation. With the use of isolated perfused porcine ileum, GLP-1 secretion was measured in response to electrical stimulation of the mixed, perivascular nerve supply...

NOD-Like Receptors in Intestinal Homeostasis and Epithelial Tissue Repair

Science.gov (United States)

Parlato, Marianna; Yeretssian, Garabet

2014-01-01

The intestinal epithelium constitutes a dynamic physical barrier segregating the luminal content from the underlying mucosal tissue. Following injury, the epithelial integrity is restored by rapid migration of intestinal epithelial cells (IECs) across the denuded area in a process known as wound healing. Hence, through a sequence of events involving restitution, proliferation and differentiation of IECs the gap is resealed and homeostasis reestablished. Relapsing damage followed by healing of the inflamed mucosa is a hallmark of several intestinal disorders including inflammatory bowel diseases (IBD). While several regulatory peptides, growth factors and cytokines stimulate restitution of the epithelial layer after injury, recent evidence in the field underscores the contribution of innate immunity in controlling this process. In particular, nucleotide-binding and oligomerization domain-like receptors (NLRs) play critical roles in sensing the commensal microbiota, maintaining homeostasis, and regulating intestinal inflammation. Here, we review the process of intestinal epithelial tissue repair and we specifically focus on the impact of NLR-mediated signaling mechanisms involved in governing epithelial wound healing during disease. PMID:24886810

The alpha cell expresses glucagon-like peptide-2 receptors and glucagon-like peptide-2 stimulates glucagon secretion from the rat pancreas

DEFF Research Database (Denmark)

de Heer, J; Pedersen, J; Orskov, C

2007-01-01

AIMS/HYPOTHESIS: Glucagon-like peptide-2 (GLP-2) is a gut hormone regulating intestinal growth and nutrient absorption. Recently, GLP-2 has been reported to stimulate glucagon secretion in healthy humans. We sought to clarify the mechanism and physiological significance of this endocrine effect. ...... of the glucagonotropic action of GLP-2 in humans....

Bile acids in regulation of intestinal physiology.

LENUS (Irish Health Repository)

Keating, Niamh

2009-10-01

In addition to their roles in facilitating lipid digestion and absorption, bile acids are recognized as important regulators of intestinal function. Exposure to bile acids can dramatically influence intestinal transport and barrier properties; in recent years, they have also become appreciated as important factors in regulating cell growth and survival. Indeed, few cells reside within the intestinal mucosa that are not altered to some degree by exposure to bile acids. The past decade saw great advances in the knowledge of how bile acids exert their actions at the cellular and molecular levels. In this review, we summarize the current understanding of the role of bile acids in regulation of intestinal physiology.

The optimization of peptide cargo bound to MHC class I molecules by the peptide-loading complex.

Science.gov (United States)

Elliott, Tim; Williams, Anthony

2005-10-01

Major histocompatibility complex (MHC) class I complexes present peptides from both self and foreign intracellular proteins on the surface of most nucleated cells. The assembled heterotrimeric complexes consist of a polymorphic glycosylated heavy chain, non-polymorphic beta(2) microglobulin, and a peptide of typically nine amino acids in length. Assembly of the class I complexes occurs in the endoplasmic reticulum and is assisted by a number of chaperone molecules. A multimolecular unit termed the peptide-loading complex (PLC) is integral to this process. The PLC contains a peptide transporter (transporter associated with antigen processing), a thiooxido-reductase (ERp57), a glycoprotein chaperone (calreticulin), and tapasin, a class I-specific chaperone. We suggest that class I assembly involves a process of optimization where the peptide cargo of the complex is edited by the PLC. Furthermore, this selective peptide loading is biased toward peptides that have a longer off-rate from the assembled complex. We suggest that tapasin is the key chaperone that directs this action of the PLC with secondary contributions from calreticulin and possibly ERp57. We provide a framework model for how this may operate at the molecular level and draw parallels with the proposed mechanism of action of human leukocyte antigen-DM for MHC class II complex optimization.

Bovine Colostrum Supplementation During Running Training Increases Intestinal Permeability

Directory of Open Access Journals (Sweden)

Grant D. Brinkworth

2009-12-01

Full Text Available Endurance exercise training can increase intestinal permeability which may contribute to the development of gastrointestinal symptoms in some athletes. Bovine colostrum (BC supplementation reduces intestinal permeability induced by non-steroidal anti-inflammatory drugs. This study aimed to determine whether BC could also reduce intestinal permeability induced by endurance exercise. Thirty healthy adult males (25.0 ± 4.7 yr; mean ± SD completed eight weeks of running three times per week for 45 minutes at their lactate threshold while consuming 60 g/day of BC, whey protein (WP or control (CON. Intestinal permeability was assessed at baseline and after eight weeks by measuring the ratio of urinary lactulose (L and rhamnose (R excretion. After eight weeks the L/R ratio increased significantly more in volunteers consuming BC (251 ± 140% compared with WP (21 ± 35%, P < 0.05 and CON (−7 ± 13%, P < 0.02. The increase in intestinal permeability with BC may have been due to BC inducing greater leakiness of tight junctions between enterocytes or by increasing macromolecular transport as it does in neonatal gut. Further research should investigate the potential for BC to increase intestinal macromolecular transport in adults.

Glucagon and glucagon-like peptides 1 and 2

DEFF Research Database (Denmark)

Holst, Jens Juul

2010-01-01

amino acid precursor, proglucagon, leaving behind proglucagon fragments (PG 1-30 and PG 72-158, the so-called major proglucagon fragment (MPGF)) that are probably inactive, the intestinal processing leads to the formation of glicentin (PG 1-69; action uncertain) and glucagon-like peptides 1 (PG 78....... After their release, the hormones are eliminated mainly in the kidneys, but both GLP-2 and in particular GLP-1, but not glucagon, are metabolized both locally and in the circulation and liver by dipeptidyl peptidase 4 (DPP-4) which inactivates the peptides, suggesting that GLP-1 acts locally rather than...

Vasoactive intestinal peptide binding sites and fibers in the brain of the pigeon Columba livia: An autoradiographic and immunohistochemical study

International Nuclear Information System (INIS)

Hof, P.R.; Dietl, M.M.; Charnay, Y.; Martin, J.L.; Bouras, C.; Palacios, J.M.; Magistretti, P.J.

1991-01-01

The distribution of vasoactive intestinal peptide (VIP) binding sites in the pigeon brain was examined by in vitro autoradiography on slide-mounted sections. A fully characterized monoiodinated form of VIP, which maintains the biological activity of the native peptide, was used throughout this study. The highest densities of binding sites were observed in the hyperstriatum dorsale, archistriatum, auditory field L of neostriatum, area corticoidea dorsolateralis and temporo-parieto-occipitalis, area parahippocampalis, tectum opticum, nucleus dorsomedialis anterior thalami, and in the periventricular area of the hypothalamus. Lower densities of specific binding occurred in the neostriatum, hyperstriatum ventrale and nucleus septi lateralis, dorsolateral area of the thalamus, and lateral and posteromedial hypothalamus. Very low to background levels of VIP binding were detected in the ectostriatum, paleostriatum primitivum, paleostriatum augmentatum, lobus parolfactorius, nucleus accumbens, most of the brainstem, and the cerebellum. The distribution of VIP-containing fibers and terminals was examined by indirect immunofluorescence using a polyclonal antibody against porcine VIP. Fibers and terminals were observed in the area corticoidea dorsolateralis, area parahippocampalis, hippocampus, hyperstriatum accessorium, hyperstriatum dorsale, archistriatum, tuberculum olfactorium, nuclei dorsolateralis and dorsomedialis of the thalamus, and throughout the hypothalamus and the median eminence. Long projecting fibers were visualized in the tractus septohippocampalis. In the brainstem VIP immunoreactive fibers and terminals were observed mainly in the substantia grisea centralis, fasciculus longitudinalis medialis, lemniscus lateralis, and in the area surrounding the nuclei of the 7th, 9th, and 10th cranial nerves

Development and Characterization of a Human and Mouse Intestinal Epithelial Cell Monolayer Platform

Directory of Open Access Journals (Sweden)

Kenji Kozuka

2017-12-01

Full Text Available Summary: We describe the development and characterization of a mouse and human epithelial cell monolayer platform of the small and large intestines, with a broad range of potential applications including the discovery and development of minimally systemic drug candidates. Culture conditions for each intestinal segment were optimized by correlating monolayer global gene expression with the corresponding tissue segment. The monolayers polarized, formed tight junctions, and contained a diversity of intestinal epithelial cell lineages. Ion transport phenotypes of monolayers from the proximal and distal colon and small intestine matched the known and unique physiology of these intestinal segments. The cultures secreted serotonin, GLP-1, and FGF19 and upregulated the epithelial sodium channel in response to known biologically active agents, suggesting intact secretory and absorptive functions. A screen of over 2,000 pharmacologically active compounds for inhibition of potassium ion transport in the mouse distal colon cultures led to the identification of a tool compound. : Siegel and colleagues describe their development of a human and mouse intestinal epithelial cell monolayer platform that maintains the cellular, molecular, and functional characteristics of tissue for each intestinal segment. They demonstrate the platform's application to drug discovery by screening a library of over 2,000 compounds to identify an inhibitor of potassium ion transport in the mouse distal colon. Keywords: intestinal epithelium, organoids, monolayer, colon, small intestine, phenotype screening assays, enteroid, colonoid

Effects of 1 alpha,25-Dihydroxyvitamin D-3 on Transporters and Enzymes of the Rat Intestine and Kidney In Vivo

NARCIS (Netherlands)

Chow, Edwin C. Y.; Sun, Huadong; Khan, Ansar A.; Groothuis, Geny M. M.; Pang, K. Sandy

1 alpha,25-Dihydroxyvitamin D-3 (1,25(OH)(2)D-3), the natural ligand of the vitamin D receptor (VDR), was found to regulate bile acid related transporters and enzymes directly and indirectly in the rat intestine and liver in vivo. The kidney is another VDR-rich target organ in which VDR regulation

Targeted PEG-based bioconjugates enhance the cellular uptake and transport of a HIV-1 TAT nonapeptide.

Science.gov (United States)

Ramanathan, S; Qiu, B; Pooyan, S; Zhang, G; Stein, S; Leibowitz, M J; Sinko, P J

2001-12-13

We previously described the enhanced cell uptake and transport of R.I-K(biotin)-Tat9, a large ( approximately 1500 Da) peptidic inhibitor of HIV-1 Tat protein, via SMVT, the intestinal biotin transporter. The aim of the present study was to investigate the feasibility of targeting biotinylated PEG-based conjugates to SMVT in order to enhance cell uptake and transport of Tat9. The 29 kDa peptide-loaded bioconjugate (PEG:(R.I-Cys-K(biotin)-Tat9)8) used in these studies contained eight copies of R.I-K(biotin)-Tat9 appended to PEG by means of a cysteine linkage. The absorptive transport of biotin-PEG-3400 (0.6-100 microM) and the bioconjugate (0.1-30 microM) was studied using Caco-2 cell monolayers. Inhibition of biotin-PEG-3400 by positive controls (biotin, biocytin, and desthiobiotin) was also determined. Uptake of these two compounds was also determined in CHO cells transfected with human SMVT (CHO/hSMVT) and control cells (CHO/pSPORT) over the concentration ranges of 0.05-12.5 microM and 0.003-30 microM, respectively. Nonbiotinylated forms of these two compounds, PEG-3350 and PEG:(R.I-Cys-K-Tat9)8, were used in the control studies. Biotin-PEG-3400 transport was found to be concentration-dependent and saturable in Caco-2 cells (K(m)=6.61 microM) and CHO/hSMVT cells (K(m)=1.26 microM). Transport/uptake was significantly inhibited by positive control substrates of SMVT. PEG:(R.I-Cys-K(biotin)Tat9)8 also showed saturable transport kinetics in Caco-2 cells (K(m)=6.13 microM) and CHO/hSMVT cells (K(m)=8.19 microM). Maximal uptake in molar equivalents of R.I-Cys-K(biotin)Tat9 was 5.7 times greater using the conjugate versus the biotinylated peptide alone. Transport of the nonbiotinylated forms was significantly lower (PPEG-3400 and PEG:(R.I-Cys-K(biotin)Tat9)8 interact with human SMVT to enhance the cellular uptake and transport of these larger molecules and that targeted bioconjugates may have potential for enhancing the cellular uptake and transport of small peptide

Modulation of Intestinal Paracellular Transport by Bacterial Pathogens.

Science.gov (United States)

Roxas, Jennifer Lising; Viswanathan, V K

2018-03-25

The passive and regulated movement of ions, solutes, and water via spaces between cells of the epithelial monolayer plays a critical role in the normal intestinal functioning. This paracellular pathway displays a high level of structural and functional specialization, with the membrane-spanning complexes of the tight junctions, adherens junctions, and desmosomes ensuring its integrity. Tight junction proteins, like occludin, tricellulin, and the claudin family isoforms, play prominent roles as barriers to unrestricted paracellular transport. The past decade has witnessed major advances in our understanding of the architecture and function of epithelial tight junctions. While it has been long appreciated that microbes, notably bacterial and viral pathogens, target and disrupt junctional complexes and alter paracellular permeability, the precise mechanisms remain to be defined. Notably, renewed efforts will be required to interpret the available data on pathogen-mediated barrier disruption in the context of the most recent findings on tight junction structure and function. While much of the focus has been on pathogen-induced dysregulation of junctional complexes, commensal microbiota and their products may influence paracellular permeability and contribute to the normal physiology of the gut. Finally, microbes and their products have become important tools in exploring host systems, including the junctional properties of epithelial cells. © 2018 American Physiological Society. Compr Physiol 8:823-842, 2018. Copyright © 2018 American Physiological Society. All rights reserved.

Naturally occurring glucagon-like peptide-2 (GLP-2) receptors in human intestinal cell lines.

Science.gov (United States)

Sams, Anette; Hastrup, Sven; Andersen, Marie; Thim, Lars

2006-02-17

Although clinical trials with GLP-2 receptor agonists are currently ongoing, the mechanisms behind GLP-2-induced intestinal epithelial growth remain to be understood. To approach the GLP-2 mechanism of action this study aimed to identify intestinal cell lines endogenously expressing the GLP-2 receptor. Here we report the first identification of a cell line endogenously expressing functional GLP-2 receptors. The human intestinal epithelial cell line, FHC, expressed GLP-2 receptor encoding mRNA (RT-PCR) and GLP-2 receptor protein (Western blot). In cultured FHC cells, GLP-2 induced concentration dependent cAMP accumulation (pEC(50)=9.7+/-0.04 (mean+/-S.E.M., n=4)). In addition, a naturally occurring human intestinal fibroblast cell line, 18Co, endogenously expressing GLP-2 receptor encoding mRNA (RT-PCR) and protein (Western blot) was identified. No receptor functionality (binding or G-protein signalling) could be demonstrated in 18Co cells. The identified gut-relevant cell lines provide tools for future clarification of the mechanisms underlying GLP-2-induced epithelial growth.

Jumping Hurdles: Peptides Able To Overcome Biological Barriers.

Science.gov (United States)

Sánchez-Navarro, Macarena; Teixidó, Meritxell; Giralt, Ernest

2017-08-15

The cell membrane, the gastrointestinal tract, and the blood-brain barrier (BBB) are good examples of biological barriers that define and protect cells and organs. They impose different levels of restriction, but they also share common features. For instance, they all display a high lipophilic character. For this reason, hydrophilic compounds, like peptides, proteins, or nucleic acids have long been considered as unable to bypass them. However, the discovery of cell-penetrating peptides (CPPs) opened a vast field of research. Nowadays, CPPs, homing peptides, and blood-brain barrier peptide shuttles (BBB-shuttles) are good examples of peptides able to target and to cross various biological barriers. CPPs are a group of peptides able to interact with the plasma membrane and enter the cell. They display some common characteristics like positively charged residues, mainly arginines, and amphipathicity. In this field, our group has been focused on the development of proline rich CPPs and in the analysis of the importance of secondary amphipathicity in the internalization process. Proline has a privileged structure being the only amino acid with a secondary amine and a cyclic side chain. These features constrain its structure and hamper the formation of H-bonds. Taking advantage of this privileged structure, three different families of proline-rich peptides have been developed, namely, a proline-rich dendrimer, the sweet arrow peptide (SAP), and a group of foldamers based on γ-peptides. The structure and the mechanism of internalization of all of them has been evaluated and analyzed. BBB-shuttles are peptides able to cross the BBB and to carry with them compounds that cannot reach the brain parenchyma unaided. These peptides take advantage of the natural transport mechanisms present at the BBB, which are divided in active and passive transport mechanisms. On the one hand, we have developed BBB-shuttles that cross the BBB by a passive transport mechanism, like

New insights into the molecular mechanism of intestinal fatty acid absorption.

Science.gov (United States)

Wang, Tony Y; Liu, Min; Portincasa, Piero; Wang, David Q-H

2013-11-01

Dietary fat is one of the most important energy sources of all the nutrients. Fatty acids, stored as triacylglycerols (also called triglycerides) in the body, are an important reservoir of stored energy and derived primarily from animal fats and vegetable oils. Although the molecular mechanisms for the transport of water-insoluble amphipathic fatty acids across cell membranes have been debated for many years, it is now believed that the dominant means for intestinal fatty acid uptake is via membrane-associated fatty acid-binding proteins, that is, fatty acid transporters on the apical membrane of enterocytes. These findings indicate that intestinal fatty acid absorption is a multistep process that is regulated by multiple genes at the enterocyte level, and intestinal fatty acid absorption efficiency could be determined by factors influencing intraluminal fatty acid molecules across the brush border membrane of enterocytes. To facilitate research on intestinal, hepatic and plasma triacylglycerol metabolism, it is imperative to establish standard protocols for precisely and accurately measuring the efficiency of intestinal fatty acid absorption in humans and animal models. In this review, we will discuss the chemical structure and nomenclature of fatty acids and summarize recent progress in investigating the molecular mechanisms underlying the intestinal absorption of fatty acids, with a particular emphasis on the physical chemistry of intestinal lipids and the molecular physiology of intestinal fatty acid transporters. A better understanding of the molecular mechanism of intestinal fatty acid absorption should lead to novel approaches to the treatment and the prevention of fatty acid-related metabolic diseases that are prevalent worldwide. © 2013 Stichting European Society for Clinical Investigation Journal Foundation. Published by John Wiley & Sons Ltd.

Gliadin induces an increase in intestinal permeability and zonulin release by binding to the chemokine receptor CXCR3.

Science.gov (United States)

Lammers, Karen M; Lu, Ruliang; Brownley, Julie; Lu, Bao; Gerard, Craig; Thomas, Karen; Rallabhandi, Prasad; Shea-Donohue, Terez; Tamiz, Amir; Alkan, Sefik; Netzel-Arnett, Sarah; Antalis, Toni; Vogel, Stefanie N; Fasano, Alessio

2008-07-01

Celiac disease is an immune-mediated enteropathy triggered by gliadin, a component of the grain protein gluten. Gliadin induces an MyD88-dependent zonulin release that leads to increased intestinal permeability, a postulated early element in the pathogenesis of celiac disease. We aimed to establish the molecular basis of gliadin interaction with intestinal mucosa leading to intestinal barrier impairment. Alpha-gliadin affinity column was loaded with intestinal mucosal membrane lysates to identify the putative gliadin-binding moiety. In vitro experiments with chemokine receptor CXCR3 transfectants were performed to confirm binding of gliadin and/or 26 overlapping 20mer alpha-gliadin synthetic peptides to the receptor. CXCR3 protein and gene expression were studied in intestinal epithelial cell lines and human biopsy specimens. Gliadin-CXCR3 interaction was further analyzed by immunofluorescence microscopy, laser capture microscopy, real-time reverse-transcription polymerase chain reaction, and immunoprecipitation/Western blot analysis. Ex vivo experiments were performed using C57BL/6 wild-type and CXCR3(-/-) mouse small intestines to measure intestinal permeability and zonulin release. Affinity column and colocalization experiments showed that gliadin binds to CXCR3 and that at least 2 alpha-gliadin 20mer synthetic peptides are involved in this binding. CXCR3 is expressed in mouse and human intestinal epithelia and lamina propria. Mucosal CXCR3 expression was elevated in active celiac disease but returned to baseline levels following implementation of a gluten-free diet. Gliadin induced physical association between CXCR3 and MyD88 in enterocytes. Gliadin increased zonulin release and intestinal permeability in wild-type but not CXCR3(-/-) mouse small intestine. Gliadin binds to CXCR3 and leads to MyD88-dependent zonulin release and increased intestinal permeability.

Steviol Glycoside Rebaudioside A Induces Glucagon-like Peptide-1 and Peptide YY Release in a Porcine ex Vivo Intestinal Model

NARCIS (Netherlands)

Ripken, D.; Wielen, N. van der; Wortelboer, H.M.; Meijerink, J.; Witkamp, R.F.; Hendriks, H.F.J.

2014-01-01

Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) are hormones important for satiation and are involved in the process called “ileal brake”. The aim of this study was to investigate the GLP-1- and PYY-stimulating efficacy of rebaudioside A, casein, and sucrose. This was studied using tissue

Steviol glycoside rebaudioside A induces glucagon-like peptide-1 and peptide YY release in a porcine ex vivo intestinal model

NARCIS (Netherlands)

Ripken, D.; Wielen, van der N.; Wortelboer, H.M.; Meijerink, J.; Witkamp, R.F.; Hendriks, H.F.

2014-01-01

Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) are hormones important for satiation and are involved in the process called "ileal brake". The aim of this study was to investigate the GLP-1- and PYY-stimulating efficacy of rebaudioside A, casein, and sucrose. This was studied using tissue

Self-assembly of pi-conjugated peptides in aqueous environments leading to energy-transporting bioelectronic nanostructures

Energy Technology Data Exchange (ETDEWEB)

Tavor, John [Johns Hopkins Univ., Baltimore, MD (United States)

2016-12-06

The realization of new supramolecular pi-conjugated organic structures inspired and driven by peptide-based self-assembly will offer a new approach to interface with the biotic environment in a way that will help to meet many DOE-recognized grand challenges. Previously, we developed pi-conjugated peptides that undergo supramolecular self-assembly into one-dimensional (1-D) organic electronic nanomaterials under benign aqueous conditions. The intermolecular interactions among the pi-conjugated organic segments within these nanomaterials lead to defined perturbations of their optoelectronic properties and yield nanoscale conduits that support energy transport within individual nanostructures and throughout bulk macroscopic collections of nanomaterials. Our objectives for future research are to construct and study biomimetic electronic materials for energy-related technology optimized for harsher non-biological environments where peptide-driven self-assembly enhances pi-stacking within nanostructured biomaterials, as detailed in the following specific tasks: (1) synthesis and detailed optoelectronic characterization of new pi-electron units to embed within homogeneous self assembling peptides, (2) molecular and data-driven modeling of the nanomaterial aggregates and their higher-order assemblies, and (3) development of new hierarchical assembly paradigms to organize multiple electronic subunits within the nanomaterials leading to heterogeneous electronic properties (i.e. gradients and localized electric fields). These intertwined research tasks will lead to the continued development and fundamental mechanistic understanding of a powerful bioinspired materials set capable of making connections between nanoscale electronic materials and macroscopic bulk interfaces, be they those of a cell, a protein or a device.

Antifibrogenic Effects of the Antimicrobial Peptide Cathelicidin in Murine Colitis-Associated FibrosisSummary

Directory of Open Access Journals (Sweden)

Jun Hwan Yoo

2015-01-01

Full Text Available Background & Aims: Cathelicidin (LL-37 in human and mCRAMP in mice represents a family of endogenous antimicrobial peptides with anti-inflammatory effects. LL-37 also suppresses collagen synthesis, an important fibrotic response, in dermal fibroblasts. Here, we determined whether exogenous cathelicidin administration modulates intestinal fibrosis in two animal models of intestinal inflammation and in human colonic fibroblasts. Methods: C57BL/6J mice (n = 6 per group were administered intracolonically with a trinitrobenzene sulphonic acid (TNBS enema to induce chronic (6–7 weeks colitis with fibrosis. We administered mCRAMP peptide (5 mg/kg every 3 day, week 5–7 or cathelicidin gene (Camp-expressing lentivirus (107 infectious units week 4 intracolonically or intravenously, respectively. We then infected 129Sv/J mice with Salmonella typhimurium orally to induce cecal inflammation with fibrosis. Camp-expressing lentivirus (107 infectious units day 11 was administered intravenously. Results: TNBS-induced chronic colitis was associated with increased colonic collagen (col1a2 mRNA expression. Intracolonic cathelicidin (mCRAMP peptide administration or intravenous delivery of lentivirus-overexpressing cathelicidin gene significantly reduced colonic col1a2 mRNA expression in TNBS-exposed mice compared with vehicle administration. Salmonella infection also caused increased cecal inflammation associated with collagen (col1a2 mRNA expression that was prevented by intravenous delivery of Camp-expressing lentivirus. Exposure of human primary intestinal fibroblasts and human colonic CCD-18Co fibroblasts to transforming growth factor-β1 (TGF-β1 and/or insulin-like growth factor 1 induced collagen protein and mRNA expression, which was reduced by LL-37 (3–5 μM through a MAP kinase-dependent mechanism. Conclusions: Cathelicidin can reverse intestinal fibrosis by directly inhibiting collagen synthesis in colonic fibroblasts. Keywords

Oral Administration of Probiotics Increases Paneth Cells and Intestinal Antimicrobial Activity

Directory of Open Access Journals (Sweden)

Silvia I. Cazorla

2018-04-01

Full Text Available The huge amount of intestinal bacteria represents a continuing threat to the intestinal barrier. To meet this challenge, gut epithelial cells produce antimicrobial peptides (AMP that act at the forefront of innate immunity. We explore whether this antimicrobial activity and Paneth cells, the main intestinal cell responsible of AMP production, are influenced by probiotics administration, to avoid the imbalance of intestinal microbiota and preserve intestinal barrier. Administration of Lactobacillus casei CRL 431 (Lc 431 and L. paracasei CNCM I-1518 (Lp 1518 to 42 days old mice, increases the number of Paneth cells on small intestine, and the antimicrobial activity against the pathogens Staphylococcus aureus and Salmonella Typhimurium in the intestinal fluids. Specifically, strong damage of the bacterial cell with leakage of cytoplasmic content, and cellular fragmentation were observed in S. Typhimurium and S. aureus. Even more important, probiotics increase the antimicrobial activity of the intestinal fluids at the different ages, from weaning (21 days old to old age (180 days old. Intestinal antimicrobial activity stimulated by oral probiotics, do not influence significantly the composition of total anaerobic bacteria, lactobacilli and enterobacteria in the large intestine, at any age analyzed. This result, together with the antimicrobial activity observed against the same probiotic bacteria; endorse the regular consumption of probiotics without adverse effect on the intestinal homeostasis in healthy individuals. We demonstrate that oral probiotics increase intestinal antimicrobial activity and Paneth cells in order to strengthen epithelial barrier against pathogens. This effect would be another important mechanism by which probiotics protect the host mainly against infectious diseases.

Bioactive dietary peptides and amino acids in inflammatory bowel disease.

Science.gov (United States)

Zhang, Hua; Hu, Chien-An A; Kovacs-Nolan, Jennifer; Mine, Yoshinori

2015-10-01

Inflammatory bowel disease (IBD), most commonly ulcerative colitis (UC) and Crohn's disease (CD), is a chronic inflammation of the gastrointestinal tract. Patients affected with IBD experience symptoms including abdominal pain, persistent diarrhea, rectal bleeding, and weight loss. There is no cure for IBD; thus treatments typically focus on preventing complications, inducing and maintaining remission, and improving quality of life. During IBD, dysregulation of the intestinal immune system leads to increased production of pro-inflammatory cytokines, such as TNF-α and IL-6, and recruitment of activated immune cells to the intestine, causing tissue damage and perpetuating the inflammatory response. Recent biological therapies targeting specific inflammatory cytokines or pathways, in particular TNF-α, have shown promise, but not all patients respond to treatment, and some individuals become intolerant to treatment over time. Dietary peptides and amino acids (AAs) have been shown to modulate intestinal immune functions and influence inflammatory responses, and may be useful as alternative or ancillary treatments in IBD. This review focuses on dietary interventions for IBD treatment, in particular the role of dietary peptides and AAs in reducing inflammation, oxidative stress, and apoptosis in the gut, as well as recent advances in the cellular mechanisms responsible for their anti-inflammatory activity.

Intestinal CREBH overexpression prevents high-cholesterol diet-induced hypercholesterolemia by reducing Npc1l1 expression

Directory of Open Access Journals (Sweden)

Takuya Kikuchi

2016-11-01

Conclusion: Intestinal CREBH regulates dietary cholesterol flow from the small intestine by controlling the expression of multiple intestinal transporters. We propose that intestinal CREBH could be a therapeutic target for hypercholesterolemia.

Does vasoactive intestinal polypeptide mediate the pathophysiology of bowel obstruction?

Science.gov (United States)

Basson, M D; Fielding, L P; Bilchik, A J; Zucker, K A; Ballantyne, G H; Sussman, J; Adrian, T E; Modlin, I M

1989-01-01

We hypothesized that bioactive peptides might be released into the portal circulation and mediate pathophysiologic alterations accompanying small bowel obstruction. We studied this question in a subacute canine small bowel obstruction model using 50 percent diameter occlusion. Control animals underwent sham laparotomy. Vasoactive intestinal peptide (VIP), peptide YY, and gastrin were measured in portal and systemic plasma by specific radioimmunoassays at 24-hour intervals as the obstruction progressed to completion over 5 days. All peptides in both groups demonstrated portal and peripheral gradients. In control dogs, peptide concentrations did not change postoperatively but VIP increased markedly in obstructed dogs, demonstrating a median portal level of 95 pmol/liter at 96 hours compared with 31.5 pmol/liter in control animals. These portal VIP levels are known to cause hypersecretion and splanchnic vasodilation in experimental models. The release of vasoactive compounds such as VIP may mediate local pathophysiology in human small bowel obstruction. A similar explanation of the systemic effects is consistent with the known cardiopulmonary bioactivity of VIP.

Dyslipidaemia--hepatic and intestinal cross-talk.

LENUS (Irish Health Repository)

Tomkin, Gerald H

2010-06-01

Cholesterol metabolism is tightly regulated with the majority of de novo cholesterol synthesis occurring in the liver and intestine. 3 Hydroxy-3-methylglutaryl coenzyme A reductase, a major enzyme involved in cholesterol synthesis, is raised in both liver and intestine in diabetic animals. Niemann PickC1-like1 protein regulates cholesterol absorption in the intestine and facilitates cholesterol transport through the liver. There is evidence to suggest that the effect of inhibition of Niemann PickC1-like1 lowers cholesterol through its effect not only in the intestine but also in the liver. ATP binding cassette proteins G5\\/G8 regulate cholesterol re-excretion in the intestine and in the liver, cholesterol excretion into the bile. Diabetes is associated with reduced ATP binding cassette protein G5\\/G8 expression in both the liver and intestine in animal models. Microsomal triglyceride transfer protein is central to the formation of the chylomicron in the intestine and VLDL in the liver. Microsomal triglyceride transfer protein mRNA is increased in diabetes in both the intestine and liver. Cross-talk between the intestine and liver is poorly documented in humans due to the difficulty in obtaining liver biopsies but animal studies are fairly consistent in showing relationships that explain in part mechanisms involved in cholesterol homeostasis.

Exogenous glucagon-like peptide-2 (GLP-2) augments GLP-2 receptor mRNA and maintains proglucagon mRNA levels in resected rats

DEFF Research Database (Denmark)

Koopmann, Matthew C; Nelson, David W; Murali, Sangita G

2008-01-01

BACKGROUND: Glucagon-like peptide-2 (GLP-2) is a nutrient-dependent proglucagon-derived hormone that stimulates intestinal adaptive growth. Our aim was to determine whether exogenous GLP-2 increases resection-induced adaptation without diminishing endogenous proglucagon and GLP-2 receptor express...... augments adaptive growth and digestive capacity of the residual small intestine in a rat model of mid-small bowel resection by increasing plasma GLP-2 concentrations and GLP-2 receptor expression without diminishing endogenous proglucagon expression.......BACKGROUND: Glucagon-like peptide-2 (GLP-2) is a nutrient-dependent proglucagon-derived hormone that stimulates intestinal adaptive growth. Our aim was to determine whether exogenous GLP-2 increases resection-induced adaptation without diminishing endogenous proglucagon and GLP-2 receptor...

Determination of S-methyl-L-methionine (SMM) from Brassicaceae Family Vegetables and Characterization of the Intestinal Transport of SMM by Caco-2 Cells.

Science.gov (United States)

Song, Ji-Hoon; Lee, Hae-Rim; Shim, Soon-Mi

2017-01-01

The objectives of the current study were to determine S-methyl-L-methionine (SMM) from various Brassicaceae family vegetables by using validated analytical method and to characterize the intestinal transport mechanism of SMM by the Caco-2 cells. The SMM is well known to provide therapeutic activity in peptic ulcers. The amount of SMM from various Brassicaceae family vegetables ranged from 89.08 ± 1.68 μg/g to 535.98 ± 4.85 μg/g of dry weight by using validated ultra-performance liquid chromatography-electrospray ionization-mass spectrometry method. For elucidating intestinal transport mechanism, the cells were incubated with or without transport inhibitors, energy source, or a metabolic inhibitor. Phloridzin and verapamil as inhibitors of sodium glucose transport protein (SGLT1) and P-glycoprotein, respectively, were not responsible for cellular uptake of SMM. Glucose and sodium azide were not affected by the cellular accumulation of SMM. The efflux ratio of SMM was 0.26, implying that it is not effluxed through Caco-2 cells. The apparent coefficient permeability (P app ) of SMM was 4.69 × 10 -5 cm/s, indicating that it will show good oral absorption in in vivo. © 2016 Institute of Food Technologists®.

Circadian regulation of epithelial functions in the intestine

Czech Academy of Sciences Publication Activity Database

Pácha, Jiří; Sumová, Alena

2013-01-01

Roč. 208, č. 1 (2013), s. 11-24 ISSN 1748-1708 R&D Projects: GA ČR(CZ) GAP303/10/0969; GA ČR(CZ) GAP303/11/0668 Institutional support: RVO:67985823 Keywords : circadian rhythms * intestine * colon * proliferation * digestion * intestinal transport Subject RIV: ED - Physiology Impact factor: 4.251, year: 2013

Autophagy and tight junction proteins in the intestine and intestinal diseases

Directory of Open Access Journals (Sweden)

Chien-An A. Hu

2015-09-01

Full Text Available The intestinal epithelium (IE forms an indispensible barrier and interface between the intestinal interstitium and the luminal environment. The IE regulates water, ion and nutrient transport while providing a barrier against toxins, pathogens (bacteria, fungi and virus and antigens. The apical intercellular tight junctions (TJ are responsible for the paracellular barrier function and regulate trans-epithelial flux of ions and solutes between adjacent cells. Increased intestinal permeability caused by defects in the IE TJ barrier is considered an important pathogenic factor for the development of intestinal inflammation, diarrhea and malnutrition in humans and animals. In fact, defects in the IE TJ barrier allow increased antigenic penetration, resulting in an amplified inflammatory response in inflammatory bowel disease (IBD, necrotizing enterocolitis and ischemia-reperfusion injury. Conversely, the beneficial enhancement of the intestinal TJ barrier has been shown to resolve intestinal inflammation and apoptosis in both animal models of IBD and human IBD. Autophagy (self-eating mechanism is an intracellular lysosome-dependent degradation and recycling pathway essential for cell survival and homeostasis. Dysregulated autophagy has been shown to be directly associated with many pathological processes, including IBD. Importantly, the crosstalk between IE TJ and autophagy has been revealed recently. We showed that autophagy enhanced IE TJ barrier function by increasing transepithelial resistance and reducing the paracellular permeability of small solutes and ions, which is, in part, by targeting claudin-2, a cation-selective, pore-forming, transmembrane TJ protein, for lysosome (autophagy-mediated degradation. Interestingly, previous studies have shown that the inflamed intestinal mucosa in patients with active IBD has increased claudin-2 expression. In addition, inflammatory cytokines (for example, tumor necrosis factor-α, interleukin-6

Development of Yam Dioscorin-Loaded Nanoparticles for Paracellular Transport Across Human Intestinal Caco-2 Cell Monolayers.

Science.gov (United States)

Hsieh, Hung-Ling; Lee, Chia-Hung; Lin, Kuo-Chih

2018-02-07

Dioscorins, the major storage proteins of yam tubers, exert immunomodulatory activities. To improve oral bioavailability of dioscorins in the intestine, recombinant dioscorin (rDioscorin) was coated with N,N,N-trimethyl chitosan (TMC) and tripolyphosphate (TPP), resulting in the formation of TMC-rDio-TPP nanoparticles (NPs). The loading capacity and entrapment efficiency of rDioscorin in the NPs were 26 ± 0.7% and 61 ± 1.4%, respectively. The NPs demonstrated a substantial release profile in the pH environment of the jejunum. The rDioscorin released from the NPs stimulated proliferation and phagocytosis of the macrophage RAW264.7 and activated the gene expression of IL-1β and IL-6. Incubation of the NPs in the Caco-2 cell monolayer led to a 5.2-fold increase of P app compared with rDioscorin alone, suggesting that rDioscorin, with the assistance of TMC, can be promptly transported across the intestinal epithelia. These results demonstrate that the TMC-rDio-TPP NPs can be utilized for elucidating the immunopharmacological effects of dioscorins through oral delivery.

Synthesis of protein in intestinal cells exposed to cholera toxin

International Nuclear Information System (INIS)

Peterson, J.W.; Berg, W.D. Jr.; Coppenhaver, D.H.

1987-01-01

The mechanism by which cyclic adenosine monophosphate (AMP), formed by intestinal epithelial cells in response to cholera toxin, ultimately results in alterations in water and electrolyte transport is poorly understood. Several studies have indicated that inhibitors of transcription or translation block much of the transport of ions and water in the intestine and edema formation in tissue elicited by cholera toxin. Data presented in this study confirmed the inhibitory effects of cycloheximide on cholera toxin-induced fluid accumulation in the rabbit intestinal loop model. Neither cycloheximide nor actinomycin D altered the amount of cyclic AMP that accumulated in intestinal cells and Chinese hamster ovary cells exposed to cholera toxin. An increase in [ 3 H] leucine incorporation was readily demonstrable in intestinal epithelial cells from rabbits challenged with Vibrio cholerae. Similarly, intestinal epithelial cells incubated with cholera toxin for 4 hr synthesized substantially more protein than controls as determined by relative incorporation of [ 35 S] methionine. Most of the new protein synthesized in response to cholera toxin was membrane associated and of high molecular weight. The possible significance of the toxin-induced protein relative to cholera pathogenesis was discussed

Transporters for the Intestinal Absorption of Cholesterol, Vitamin E, and Vitamin K

OpenAIRE

Yamanashi, Yoshihide; Takada, Tappei; Kurauchi, Ryoya; Tanaka, Yusuke; Komine, Toko; Suzuki, Hiroshi

2017-01-01

Humans cannot synthesize fat-soluble vitamins such as vitamin E and vitamin K. For this reason, they must be obtained from the diet via intestinal absorption. As the deficiency or excess of these vitamins has been reported to cause several types of diseases and disorders in humans, the intestinal absorption of these nutrients must be properly regulated to ensure good health. However, the mechanism of their intestinal absorption remains poorly understood. Recent studies on cholesterol using ge...

Mechanistic studies of ocular peptide absorption and its enhancement by various penetration enhancers

International Nuclear Information System (INIS)

Rojanasakul, Y.

1989-01-01

Two major aspects of corneal peptide absorption, namely the transport mechanisms and the promoting effect of some penetration enhancers, were investigated. Studies on transport mechanisms involve (a) identification of transport pathways of peptides across the cornea, (b) determination of rate-limiting barrier(s) for peptide absorption, and (c) permselective properties of the cornea. To study the transport pathways of peptides, four model peptides differing in molecular size and charge were either fluorescently or radioactively labeled and their movement across the cornea was detected by laser scanning confocal microscopy and autoradiography. Results from these studies indicate that peptides can penetrate the cornea via different pathways, depending on the physicochemical properties and membrane specificity of the peptides. In all cases, the outermost layer of the corneal epithelium presents the rate-limiting barrier for peptide absorption. The results also indicate a charge discrimination effect to transport of negatively charged peptides. In permselectivity studies, it has been shown that the cornea, due to the presence of ionizable charged groups, is amphoteric and exhibits dual selective characteristics to transport of charged molecules. At pH's above the isoelectric point, 3.2, the cornea carries a net negative charge and is selective to positively-charged molecules. Below the isoelectric pH, the reverse is valid. The promoting mechanisms of penetration enhancers were studied microscopically using confocal fluorescence microscopy with the aid of a specific fluorescent membrane probe (3,3'-dioctadecyloxacarbocyanine) and a non-permeating polar tracer. All enhancers, including chelators, non-ionic surfactants, bile salts, and cytoskeleton-active agents, significantly increase membrane permeability depending on concentration and exposure time

Updates in weight loss surgery and gastrointestinal peptides

DEFF Research Database (Denmark)

Svane, Maria Saur; Bojsen-Møller, Kirstine N; Madsbad, Sten

2015-01-01

PURPOSE OF REVIEW: Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy are referred to as 'metabolic surgery' due to hormonal shifts with impacts on diabetes remission and weight loss. The purpose of this review is to summarize recent findings in mechanisms underlying beneficial effects...... of weight loss surgery. RECENT FINDINGS: Importantly, gut hormone secretion is altered after RYGB and sleeve gastrectomy due to accelerated transit of nutrients to distal parts of the small intestine, leading to excessive release of L-cell peptide hormones [e.g. glucagon-like peptide-1 (GLP-1), peptide YY......; as demonstrated by relapse of impaired glucose tolerance in studies blocking the GLP-1 receptor by exendin 9-39, and later after major weight loss increased peripheral insulin sensitivity. Gut hormone secretion changes towards a more anorectic profile and is likely important for less caloric intake and weight...

Effects of dietary glucose and sodium chloride on intestinal glucose absorption of common carp (Cyprinus carpio L.).

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Qin, Chaobin; Yang, Liping; Zheng, Wenjia; Yan, Xiao; Lu, Ronghua; Xie, Dizhi; Nie, Guoxing

2018-01-08

The co-transport of sodium and glucose is the first step for intestinal glucose absorption. Dietary glucose and sodium chloride (NaCl) may facilitate this physiological process in common carp (Cyprinus carpio L.). To test this hypothesis, we first investigated the feeding rhythm of intestinal glucose absorption. Carps were fed to satiety once a day (09:00 a.m.) for 1 month. Intestinal samples were collected at 01:00, 05:00, 09:00, 13:00, 17:00 and 21:00. Result showed that food intake greatly enhanced sodium/glucose cotransporter 1 (SGLT1) and glucose transporter type 2 (GLUT2) expressions, and improved glucose absorption, with highest levels at 09:00 a.m.. Then we designed iso-nitrogenous and iso-energetic diets with graded levels of glucose (10%, 20%, 30%, 40% and 50%) and NaCl (0%, 1%, 3% and 5%), and submitted to feeding trial for 10 weeks. The expressions of SGLT1 and GLUT2, brush border membrane vesicles (BBMVs) glucose transport and intestinal villus height were determined after the feeding trial. Increasing levels of dietary glucose and NaCl up-regulated mRNA and protein levels of SGLT1 and GLUT2, enhanced BBMVs glucose transport in the proximal, mid and distal intestine. As for histological adaptive response, however, high-glucose diet prolonged while high-NaCl diet shrank intestinal villus height. Furthermore, we also found that higher mRNA levels of SGLT1 and GLUT2, higher glucose transport capacity of BBMVs, and higher intestinal villus were detected in the proximal and mid intestine, compared to the distal part. Taken together, our study indicated that intestinal glucose absorption in carp was primarily occurred in the proximal and mid intestine, and increasing levels of dietary glucose and NaCl enhanced intestinal glucose absorption in carp. Copyright © 2017 Elsevier Inc. All rights reserved.

Oral delivery of peptides and proteins using lipid-based drug delivery systems

DEFF Research Database (Denmark)

Li, Ping; Nielsen, Hanne Mørck; Müllertz, Anette

2012-01-01

INTRODUCTION: In order to successfully develop lipid-based drug delivery systems (DDS) for oral administration of peptides and proteins, it is important to gain an understanding of the colloid structures formed by these DDS, the mode of peptide and protein incorporation as well as the mechanism...... by which intestinal absorption of peptides and proteins is promoted. AREAS COVERED: The present paper reviews the literature on lipid-based DDS, employed for oral delivery of peptides and proteins and highlights the mechanisms by which the different lipid-based carriers are expected to overcome the two...... and proteins. EXPERT OPINION: Lipid-based DDS are safe and suitable for oral delivery of peptides and proteins. Significant progress has been made in this area with several technologies on clinical trials. However, a better understanding of the mechanism of action in vivo is needed in order to improve...

Arginine-rich intracellular delivery peptides noncovalently transport protein into living cells

International Nuclear Information System (INIS)

Wang, Y.-H.; Chen, C.-P.; Chan, M.-H.; Chang, M.; Hou, Y.-W.; Chen, H.-H.; Hsu, H.-R.; Liu, Kevin; Lee, H.-J.

2006-01-01

Plasma membranes of plant or animal cells are generally impermeable to peptides or proteins. Many basic peptides have previously been investigated and covalently cross-linked with cargoes for cellular internalization. In the current study, we demonstrate that arginine-rich intracellular delivery (AID) peptides are able to deliver fluorescent proteins or β-galactosidase enzyme into animal and plant cells, as well as animal tissue. Cellular internalization and transdermal delivery of protein could be mediated by effective and nontoxic AID peptides in a neither fusion protein nor conjugation fashion. Therefore, noncovalent AID peptides may provide a useful strategy to have active proteins function in living cells and tissues in vivo

Protease-activated receptor-2 stimulates intestinal epithelial chloride transport through activation of PLC and selective PKC isoforms.

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van der Merwe, Jacques Q; Moreau, France; MacNaughton, Wallace K

2009-06-01

Serine proteases play important physiological roles through their activity at G protein-coupled protease-activated receptors (PARs). We examined the roles that specific phospholipase (PL) C and protein kinase (PK) C (PKC) isoforms play in the regulation of PAR(2)-stimulated chloride secretion in intestinal epithelial cells. Confluent SCBN epithelial monolayers were grown on Snapwell supports and mounted in modified Ussing chambers. Short-circuit current (I(sc)) responses to basolateral application of the selective PAR(2) activating peptide, SLIGRL-NH(2), were monitored as a measure of net electrogenic ion transport caused by PAR(2) activation. SLIGRL-NH(2) induced a transient I(sc) response that was significantly reduced by inhibitors of PLC (U73122), phosphoinositol-PLC (ET-18), phosphatidylcholine-PLC (D609), and phosphatidylinositol 3-kinase (PI3K; LY294002). Immunoblot analysis revealed the phosphorylation of both PLCbeta and PLCgamma following PAR(2) activation. Pretreatment of the cells with inhibitors of PKC (GF 109203X), PKCalpha/betaI (Gö6976), and PKCdelta (rottlerin), but not PKCzeta (selective pseudosubstrate inhibitor), also attenuated this response. Cellular fractionation and immunoblot analysis, as well as confocal immunocytochemistry, revealed increases of PKCbetaI, PKCdelta, and PKCepsilon, but not PKCalpha or PKCzeta, in membrane fractions following PAR(2) activation. Pretreatment of the cells with U73122, ET-18, or D609 inhibited PKC activation. Inhibition of PI3K activity only prevented PKCdelta translocation. Immunoblots revealed that PAR(2) activation induced phosphorylation of both cRaf and ERK1/2 via PKCdelta. Inhibition of PKCbetaI and PI3K had only a partial effect on this response. We conclude that basolateral PAR(2)-induced chloride secretion involves activation of PKCbetaI and PKCdelta via a PLC-dependent mechanism resulting in the stimulation of cRaf and ERK1/2 signaling.

Separation of Peptides with Forward Osmosis Biomimetic Membranes

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Bajraktari, Niada; Madsen, Henrik T.; Gruber, Mathias F.; Truelsen, Sigurd; Jensen, Elzbieta L.; Jensen, Henrik; Hélix-Nielsen, Claus

2016-01-01

Forward osmosis (FO) membranes have gained interest in several disciplines for the rejection and concentration of various molecules. One application area for FO membranes that is becoming increasingly popular is the use of the membranes to concentrate or dilute high value compound solutions such as pharmaceuticals. It is crucial in such settings to control the transport over the membrane to avoid losses of valuable compounds, but little is known about the rejection and transport mechanisms of larger biomolecules with often flexible conformations. In this study, transport of two chemically similar peptides with molecular weight (Mw) of 375 and 692 Da across a thin film composite Aquaporin Inside™ Membrane (AIM) FO membrane was investigated. Despite the relative large size, both peptides were able to permeate the dense active layer of the AIM membrane and the transport mechanism was determined to be diffusion-based. Interestingly, the membrane permeability increased 3.65 times for the 692 Da peptide (1.39 × 10−12 m2·s−1) compared to the 375 Da peptide (0.38 × 10−12 m2·s−1). This increase thus occurs for an 85% increase in Mw but only for a 34% increase in peptide radius of gyration (Rg) as determined from molecular dynamics (MD) simulations. This suggests that Rg is a strong influencing factor for membrane permeability. Thus, an increased Rg reflects the larger peptide chains ability to sample a larger conformational space when interacting with the nanostructured active layer increasing the likelihood for permeation. PMID:27854275

Gluten-degrading bacteria are present in the human small intestine of healthy volunteers and celiac patients.

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Herrán, Alexandra R; Pérez-Andrés, Jénifer; Caminero, Alberto; Nistal, Esther; Vivas, Santiago; Ruiz de Morales, José María; Casqueiro, Javier

2017-09-01

Gluten is the only known environmental factor that triggers celiac disease. Several studies have described an imbalance between the intestinal microbiota of different individuals based on diagnoses. Moreover, recent studies have suggested that human bacteria may play an important role in gluten hydrolysis. However, there has been no research focusing on the small intestine. This study aimed to characterize the adult small intestine microbiota possibly implicated in gluten hydrolysis. Duodenal biopsies from different diagnosed individuals were cultured in a gluten-containing medium, and the grown microbiota was analyzed by culture dependent/independent methods. Results showed that gluten-degrading bacteria can be found in the human small intestine. Indeed, 114 bacterial strains belonging to 32 species were isolated; 85 strains were able to grow in a medium containing gluten as the sole nitrogen source, 31 strains showed extracellular proteolytic activity against gluten protein and 27 strains showed peptidolytic activity towards the 33 mer peptide, an immunogenic peptide for celiac disease patients. We found that there are no differences based on the diagnosis, but each individual has its own population of gluten-hydrolyzing bacteria. These bacteria or their gluten-degrading enzymes could help to improve the quality of life of celiac disease patients'. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Mechanistic insights of intestinal absorption and renal conservation of folate in chronic alcoholism.

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Wani, Nissar Ahmad; Thakur, Shilpa; Najar, Rauf Ahmad; Nada, Ritambhara; Khanduja, Krishan Lal; Kaur, Jyotdeep

2013-03-01

Folate mediated one-carbon metabolism is of fundamental importance for various cellular processes, including DNA synthesis and methylation of biological molecules. Due to the exogenous requirement of folate in mammals, there exists a well developed epithelial folate transport system for regulation of normal folate homeostasis. The intestinal and renal folate uptake is tightly and diversely regulated and disturbances in folate homeostasis like in alcoholism have pathological consequences. The study was sought to delineate the regulatory mechanism of folate uptake in intestine and reabsorption in renal tubular cells that could evaluate insights of malabsorption during alcoholism. The folate transporters PCFT and RFC were found to be associated with lipid rafts of membrane surfaces in intestine and kidney. Importantly, the observed lower intestinal and renal folate uptake was associated with decreased levels of folate transporter viz. PCFT and RFC in lipid rafts of intestinal and renal membrane surfaces. The decreased association of folate transporters in lipid rafts was associated with decreased protein and mRNA levels. In addition, immunohistochemical studies showed that alcoholic conditions deranged that localization of PCFT and RFC. These findings could explain the possible mechanistic insights that may result in folate malabsorption during alcoholism. Copyright © 2013 Elsevier Inc. All rights reserved.

Transport of the photodynamic therapy agent 5-aminolevulinic acid by distinct H+-coupled nutrient carriers coexpressed in the small intestine.

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Anderson, Catriona M H; Jevons, Mark; Thangaraju, Muthusamy; Edwards, Noel; Conlon, Nichola J; Woods, Steven; Ganapathy, Vadivel; Thwaites, David T

2010-01-01

5-Aminolevulinic acid (ALA) is a prodrug used in photodynamic therapy, fluorescent diagnosis, and fluorescent-guided resection because it leads to accumulation of the photosensitizer protoporphyrin IX (PpIX) in tumor tissues. ALA has good oral bioavailability, but high oral doses are required to obtain selective PpIX accumulation in colonic tumors because accumulation is also observed in normal gut mucosa. Structural similarities between ALA and GABA led us to test the hypothesis that the H(+)-coupled amino acid transporter PAT1 (SLC36A1) will contribute to luminal ALA uptake. Radiolabel uptake and electrophysiological measurements identified PAT1-mediated H(+)-coupled ALA symport after heterologous expression in Xenopus oocytes. The selectivity of the nontransported inhibitors 5-hydroxytryptophan and 4-aminomethylbenzoic acid for, respectively, PAT1 and the H(+)-coupled di/tripeptide transporter PepT1 (SLC15A1) were examined. 5-Hydroxytryptophan selectively inhibited PAT1-mediated amino acid uptake across the brush-border membrane of the human intestinal (Caco-2) epithelium whereas 4-aminomethylbenzoic acid selectively inhibited PepT1-mediated dipeptide uptake. The inhibitory effects of 5-hydroxytryptophan and 4-aminomethylbenzoic acid were additive, demonstrating that both PAT1 and PepT1 contribute to intestinal transport of ALA. This is the first demonstration of overlap in substrate specificity between these distinct transporters for amino acids and dipeptides. PAT1 and PepT1 expression was monitored by reverse transcriptase-polymerase chain reaction using paired samples of normal and cancer tissue from human colon. mRNA for both transporters was detected. PepT1 mRNA was increased 2.3-fold in cancer tissues. Thus, increased PepT1 expression in colonic cancer could contribute to the increased PpIX accumulation observed. Selective inhibition of PAT1 could enhance PpIX loading in tumor tissue relative to that in normal tissue.

Structured triglyceride vehicles for oral delivery of halofantrine: examination of intestinal lymphatic transport and bioavailability in conscious rats

DEFF Research Database (Denmark)

Holm, René; Porter, Christopher J H; Müllertz, Anette

2002-01-01

PURPOSE: To compare the influence of triglyceride vehicle intramolecular structure on the intestinal lymphatic transport and systemic absorption of halofantrine in conscious rats. METHODS: Conscious, lymph cannulated and nonlymph cannulated rats were dosed orally with three structurally different...... triglycerides; sunflower oil, and two structured triglycerides containing different proportion and position of medium-(M) and long-chain (L) fatty acids on the glycerol backbone. The two structured triglycerides were abbreviated MLM and LML to reflect the structural position on the glycerol. The concentration...... animals, and this was most pronounced for the animals dosed with the structured triglycerides. CONCLUSIONS: Using MLM as vehicle increases the portal absorption of halofantrine and results in similar lymphatic transport levels when compared to sunflower oil. Total absorption when assessed as absorption...

The anti-inflammatory peptide stearyl-norleucine-VIP delays disease onset and extends survival in a rat model of inherited amyotrophic lateral sclerosis.

Science.gov (United States)

Goursaud, Stéphanie; Schäfer, Sabrina; Dumont, Amélie O; Vergouts, Maxime; Gallo, Alessandro; Desmet, Nathalie; Deumens, Ronald; Hermans, Emmanuel

2015-01-01

Vasoactive intestinal peptide (VIP) has potent immune modulatory actions that may influence the course of neurodegenerative disorders associated with chronic inflammation. Here, we show the therapeutic benefits of a modified peptide agonist stearyl-norleucine-VIP (SNV) in a transgenic rat model of amyotrophic lateral sclerosis (mutated superoxide dismutase 1, hSOD1(G93A)). When administered by systemic every-other-day intraperitoneal injections during a period of 80 days before disease, SNV delayed the onset of motor dysfunction by no less than three weeks, while survival was extended by nearly two months. SNV-treated rats showed reduced astro- and microgliosis in the lumbar ventral spinal cord and a significant degree of motor neuron preservation. Throughout the treatment, SNV promoted the expression of the anti-inflammatory cytokine interleukin-10 as well as neurotrophic factors commonly considered as beneficial in amyotrophic lateral sclerosis management (glial derived neuroptrophic factor, insulin like growth factor, brain derived neurotrophic factor). The peptide nearly totally suppressed the expression of tumor necrosis factor-α and repressed the production of the pro-inflammatory mediators interleukin-1β, nitric oxide and of the transcription factor nuclear factor kappa B. Inhibition of tumor necrosis factor-α likely accounted for the observed down-regulation of nuclear factor kappa B that modulates the transcription of genes specifically involved in amyotrophic lateral sclerosis (sod1 and the glutamate transporter slc1a2). In line with this, levels of human superoxide dismutase 1 mRNA and protein were decreased by SNV treatment, while the expression and activity of the glutamate transporter-1 was promoted. Considering the large diversity of influences of this peptide on both clinical features of the disease and associated biochemical markers, we propose that SNV or related peptides may constitute promising candidates for amyotrophic lateral sclerosis

Therapeutic effects of Glucagon-Like Peptide-2 on experimental radiation enteritis in rat

International Nuclear Information System (INIS)

Torres, S.

2007-01-01

Radiation enteritis in patients treated by abdominal and pelvic radiotherapy is characterized by acute mucosal disruption and chronic intestinal fibrosis. Using a model of localized intestinal irradiation in the rat, we showed remote intestinal dysfunction outside the irradiation field along the whole gut, probably associated with perturbations in the systems regulating intestinal functions. Based on the hypothesis of consequential late effects, acute administration of Glucagon-Like Peptide-2, a growth factor with specific trophic effect on the intestinal mucosa, limited the apparition of both acute and chronic radiation enteritis. This suggests that therapeutic strategies targeting the severity of acute tissue damage may also limit chronic sequelae. The study of GLP-2 effects on epithelial cells in co-culture with either subepithelial myo-fibroblasts or enteric nervous system emphasized the problem of the modelization of complex systems in vitro, and suggested a synergic action from these different actors in vivo. (author)

Intestinal Fork Head Regulates Nutrient Absorption and Promotes Longevity

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Ekin Bolukbasi

2017-10-01

Full Text Available Reduced activity of nutrient-sensing signaling networks can extend organismal lifespan, yet the underlying biology remains unclear. We show that the anti-aging effects of rapamycin and reduced intestinal insulin/insulin growth factor (IGF signaling (IIS require the Drosophila FoxA transcription factor homolog Fork Head (FKH. Intestinal FKH induction extends lifespan, highlighting a role for the gut. FKH binds to and is phosphorylated by AKT and Target of Rapamycin. Gut-specific FKH upregulation improves gut barrier function in aged flies. Additionally, it increases the expression of nutrient transporters, as does lowered IIS. Evolutionary conservation of this effect of lowered IIS is suggested by the upregulation of related nutrient transporters in insulin receptor substrate 1 knockout mouse intestine. Our study highlights a critical role played by FKH in the gut in mediating anti-aging effects of reduced IIS. Malnutrition caused by poor intestinal absorption is a major problem in the elderly, and a better understanding of the mechanisms involved will have important therapeutic implications for human aging.

Dietary supplementation with bovine lactoferrampin-lactoferricin produced by Pichia pastoris fed-batch fermentation affects intestinal microflora in weaned piglets.

Science.gov (United States)

Tang, Xiang-Shan; Shao, Hua; Li, Tie-Jun; Tang, Zhi-Ru; Huang, Rui-Ling; Wang, Sheng-Ping; Kong, Xiang-Feng; Wu, Xin; Yin, Yu-Long

2012-10-01

This work is aimed at investigating the effects of recombinant bovine lactoferrampin-lactoferricin (LFA-LFC) instead of chlortetracycline on intestinal microflora in weaned piglets. The high cost of peptide production from either native digestion or chemical synthesis limits the clinical application of antimicrobial peptides. The expression of recombinant peptides in yeast may be an effective alternative. In the current study, recombinant LFA-LFC was produced via fed-batch fermentation in recombinant strain Pichia pastoris (KM71) XS10. Uniform design U6(6(4)) was used to optimize the fermentation conditions. The target peptide purified via cation-exchange and size-exclusion chromatography was added into the dietary of weaned piglets. After 21 days, the Lactobacilli, Bifidobacteria, and Enterobacteria in the chyme of the gut were quantified using real-time polymerase chain reaction. The results showed that approximately 82 mg of LFA-LFC was secreted into 1 L of medium under optimized conditions. Moreover, purified peptide showed strong antimicrobial activities against all the tested microorganisms. Compared with the control group, the LFA-LFC group increased the amount of Lactobacilli and Bifidobacteria (P<0.05) in the chyme of the stomach, duodenum, jejunum, ileum, colon, and caecum. These results show that dietary supplementation with LFA-LFC can affect intestinal microflora in weaned piglets.

Multiple Factors Related to the Secretion of Glucagon-Like Peptide-1

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XingChun Wang

2015-01-01

Full Text Available The glucagon-like peptide-1 is secreted by intestinal L cells in response to nutrient ingestion. It regulates the secretion and sensitivity of insulin while suppressing glucagon secretion and decreasing postprandial glucose levels. It also improves beta-cell proliferation and prevents beta-cell apoptosis induced by cytotoxic agents. Additionally, glucagon-like peptide-1 delays gastric emptying and suppresses appetite. The impaired secretion of glucagon-like peptide-1 has negative influence on diabetes, hyperlipidemia, and insulin resistance related diseases. Thus, glucagon-like peptide-1-based therapies (glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors are now well accepted in the management of type 2 diabetes. The levels of glucagon-like peptide-1 are influenced by multiple factors including a variety of nutrients. The component of a meal acts as potent stimulants of glucagon-like peptide-1 secretion. The levels of its secretion change with the intake of different nutrients. Some drugs also have influence on GLP-1 secretion. Bariatric surgery may improve metabolism through the action on GLP-1 levels. In recent years, there has been a great interest in developing effective methods to regulate glucagon-like peptide-1 secretion. This review summarizes the literature on glucagon-like peptide-1 and related factors affecting its levels.

The dominantly expressed class I molecule of the chicken MHC is explained by coevolution with the polymorphic peptide transporter (TAP) genes

DEFF Research Database (Denmark)

Walker, Brian A; Hunt, Lawrence G; Sowa, Anna K

2011-01-01

In most mammals, the MHC class I molecules are polymorphic and determine the specificity of peptide presentation, whereas the transporter associated with antigen presentation (TAP) heterodimers are functionally monomorphic. In chickens, there are two classical class I genes but only one is expres...

Role of intestinal brush border peptidases in the simulated digestion of milk proteins.

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Picariello, Gianluca; Miralles, Beatriz; Mamone, Gianfranco; Sánchez-Rivera, Laura; Recio, Isidra; Addeo, Francesco; Ferranti, Pasquale

2015-05-01

This study aimed to assess the impact of the "often neglected" intestinal brush border membranes (BBMs) hydrolases on dietary peptides, exploring the possibility that the disintegration of proteins progressed in the small intestine up to a "core" of intrinsically stable oligopeptides, persisting independently on the up-stream breakdown. Samples of sodium caseinate, skim milk powder, and whey protein isolate were submitted to in vitro simulated gastropancreatic digestion using two different procedures: (i) a simplified model involving the main compartmental specific proteases; (ii) a static digestion method based on a frameset of parameters inferred from in vivo. The gastroduodenal digesta were further hydrolyzed with peptidases from porcine jejunal BBM. The peptidomes arising from the two digestion models, characterized by combined HPLC and MS techniques, differed to some extent. However, only specific protein domains survived digestion, among which are potential bioactive or immunogenic (food allergy) peptides. The degree of hydrolysis (DH) after BBM digestion (70-77%) practically did not differ between the digestion models and significantly increased the DH after duodenal steps. Any in vitro digestion model should be supplemented with a jejunal phase to realistically determine the bioaccessibility and bioavailability of dietary peptides. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Giardia co-infection promotes the secretion of antimicrobial peptides beta-defensin 2 and trefoil factor 3 and attenuates attaching and effacing bacteria-induced intestinal disease.

Science.gov (United States)

Manko, Anna; Motta, Jean-Paul; Cotton, James A; Feener, Troy; Oyeyemi, Ayodele; Vallance, Bruce A; Wallace, John L; Buret, Andre G

2017-01-01

Our understanding of polymicrobial gastrointestinal infections and their effects on host biology remains incompletely understood. Giardia duodenalis is an ubiquitous intestinal protozoan parasite infecting animals and humans. Concomitant infections with Giardia and other gastrointestinal pathogens commonly occur. In countries with poor sanitation, Giardia infection has been associated with decreased incidence of diarrheal disease and fever, and reduced serum inflammatory markers release, via mechanisms that remain obscure. This study analyzed Giardia spp. co-infections with attaching and effacing (A/E) pathogens, and assessed whether and how the presence of Giardia modulates host responses to A/E enteropathogens, and alters intestinal disease outcome. In mice infected with the A/E pathogen Citrobacter rodentium, co-infection with Giardia muris significantly attenuated weight loss, macro- and microscopic signs of colitis, bacterial colonization and translocation, while concurrently enhancing the production and secretion of antimicrobial peptides (AMPs) mouse β-defensin 3 and trefoil factor 3 (TFF3). Co-infection of human intestinal epithelial cells (Caco-2) monolayers with G. duodenalis trophozoites and enteropathogenic Escherichia coli (EPEC) enhanced the production of the AMPs human β-defensin 2 (HBD-2) and TFF3; this effect was inhibited with treatment of G. duodenalis with cysteine protease inhibitors. Collectively, these results suggest that Giardia infections are capable of reducing enteropathogen-induced colitis while increasing production of host AMPs. Additional studies also demonstrated that Giardia was able to directly inhibit the growth of pathogenic bacteria. These results reveal novel mechanisms whereby Giardia may protect against gastrointestinal disease induced by a co-infecting A/E enteropathogen. Our findings shed new light on how microbial-microbial interactions in the gut may protect a host during concomitant infections.

Sexual maturation and changes in water and salt transport components in the kidney and intestine of three-spined stickleback (Gasterosteus aculeatus L.).

Science.gov (United States)

Madsen, Steffen S; Weber, Claus; Nielsen, Andreas M; Mohiseni, Mohammad; Bosssus, Maryline C; Tipsmark, Christian K; Borg, Bertil

2015-10-01

Mature three-spined stickleback males use spiggin threads secreted from their kidney to glue together nest material. This requires strongly hypertrophied renal proximal tubular cells, which compromises renal osmoregulatory function during the breeding period. Experimental evidence suggests that the intestine takes over hypotonic fluid secretion at that stage but the mechanism is unexplored. To unravel the molecular mechanism we analyzed and compared transcript levels of several membrane proteins involved in water and salt transport in intestinal and renal tissues, in non-mature males (NM), mature males (MM), and mature females (MF). Aquaporin paralogs aqp1a, -3a, -8aa, -8ab, -10a, and -10b, two Na(+),K(+)-ATPase alpha-1 subunit isoforms (nka547, nka976), Na(+),K(+),2Cl(-)-, and Na(+),Cl(-)-cotransporters (nkcc1a, nkcc2, ncc), the cystic fibrosis transmembrane conductance regulator (cftr) and two claudin isoforms (cldn2, cldn15a) were expressed in the intestine and kidney in all groups. There were no differences in aqp and cldn expression between intestines of NM and MM; nkcc2 was lower and nka levels tended to be higher in intestines of MM than in NM. In the kidney, aqp1 and aqp8ab levels were lower in MM than in NM, whereas aqp3a, nkcc1a, cldn15a, and spiggin were markedly elevated. This was accompanied by marked hypertrophy of kidney tubules in MM. The data support an altered kidney function in terms of water handling in mature males, whereas there was no support for modified trans-epithelial water permeability or salt-secretory activity in the intestine of mature males. Salt-absorptive activity in the intestine may, however, be down-regulated during male maturation. Copyright © 2015 Elsevier Inc. All rights reserved.

Intestine-Specific Mttp Deletion Decreases Mortality and Prevents Sepsis-Induced Intestinal Injury in a Murine Model of Pseudomonas aeruginosa Pneumonia

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Dominguez, Jessica A.; Xie, Yan; Dunne, W. Michael; Yoseph, Benyam P.; Burd, Eileen M.; Coopersmith, Craig M.; Davidson, Nicholas O.

2012-01-01

Background The small intestine plays a crucial role in the pathophysiology of sepsis and has been referred to as the “motor” of the systemic inflammatory response. One proposed mechanism is that toxic gut-derived lipid factors, transported in mesenteric lymph, induce systemic injury and distant organ failure. However, the pathways involved are yet to be defined and the role of intestinal chylomicron assembly and secretion in transporting these lipid factors is unknown. Here we studied the outcome of sepsis in mice with conditional, intestine-specific deletion of microsomal triglyceride transfer protein (Mttp-IKO), which exhibit a block in chylomicron assembly together with lipid malabsorption. Methodology/Principal Findings Mttp-IKO mice and controls underwent intratracheal injection with either Pseudomonas aeruginosa or sterile saline. Mttp-IKO mice exhibited decreased seven-day mortality, with 0/20 (0%) dying compared to 5/17 (29%) control mice (p<0.05). This survival advantage in Mttp-IKO mice, however, was not associated with improvements in pulmonary bacterial clearance or neutrophil infiltration. Rather, Mttp-IKO mice exhibited protection against sepsis-associated decreases in villus length and intestinal proliferation and were also protected against increased intestinal apoptosis, both central features in control septic mice. Serum IL-6 levels, a major predictor of mortality in human and mouse models of sepsis, were elevated 8-fold in septic control mice but remained unaltered in septic Mttp-IKO mice. Serum high density lipoprotein (HDL) levels were reduced in septic control mice but were increased in septic Mttp-IKO mice. The decreased levels of HDL were associated with decreased hepatic expression of apolipoprotein A1 in septic control mice. Conclusions/Significance These studies suggest that strategies directed at blocking intestinal chylomicron secretion may attenuate the progression and improve the outcome of sepsis through effects mediated by

Intestine-specific Mttp deletion decreases mortality and prevents sepsis-induced intestinal injury in a murine model of Pseudomonas aeruginosa pneumonia.

Directory of Open Access Journals (Sweden)

Jessica A Dominguez

Full Text Available The small intestine plays a crucial role in the pathophysiology of sepsis and has been referred to as the "motor" of the systemic inflammatory response. One proposed mechanism is that toxic gut-derived lipid factors, transported in mesenteric lymph, induce systemic injury and distant organ failure. However, the pathways involved are yet to be defined and the role of intestinal chylomicron assembly and secretion in transporting these lipid factors is unknown. Here we studied the outcome of sepsis in mice with conditional, intestine-specific deletion of microsomal triglyceride transfer protein (Mttp-IKO, which exhibit a block in chylomicron assembly together with lipid malabsorption.Mttp-IKO mice and controls underwent intratracheal injection with either Pseudomonas aeruginosa or sterile saline. Mttp-IKO mice exhibited decreased seven-day mortality, with 0/20 (0% dying compared to 5/17 (29% control mice (p<0.05. This survival advantage in Mttp-IKO mice, however, was not associated with improvements in pulmonary bacterial clearance or neutrophil infiltration. Rather, Mttp-IKO mice exhibited protection against sepsis-associated decreases in villus length and intestinal proliferation and were also protected against increased intestinal apoptosis, both central features in control septic mice. Serum IL-6 levels, a major predictor of mortality in human and mouse models of sepsis, were elevated 8-fold in septic control mice but remained unaltered in septic Mttp-IKO mice. Serum high density lipoprotein (HDL levels were reduced in septic control mice but were increased in septic Mttp-IKO mice. The decreased levels of HDL were associated with decreased hepatic expression of apolipoprotein A1 in septic control mice.These studies suggest that strategies directed at blocking intestinal chylomicron secretion may attenuate the progression and improve the outcome of sepsis through effects mediated by metabolic and physiological adaptations in both intestinal and

Tachykinin-Related Peptides Share a G Protein-Coupled Receptor with Ion Transport Peptide-Like in the Silkworm Bombyx mori.

Directory of Open Access Journals (Sweden)

Chiaki Nagai-Okatani

Full Text Available Recently, we identified an orphan Bombyx mori neuropeptide G protein-coupled receptor (BNGR-A24 as an ion transport peptide-like (ITPL receptor. BNGR-A24 belongs to the same clade as BNGR-A32 and -A33, which were recently identified as natalisin receptors. Since these three BNGRs share high similarities with known receptors for tachykinin-related peptides (TRPs, we examined whether these BNGRs can function as physiological receptors for five endogenous B. mori TRPs (TK-1-5. In a heterologous expression system, BNGR-A24 acted as a receptor for all five TRPs. In contrast, BNGR-A32 responded only to TK-5, and BNGR-A33 did not respond to any of the TRPs. These findings are consistent with recent studies on the ligand preferences for B. mori natalisins. Furthermore, we evaluated whether the binding of ITPL and TRPs to BNGR-A24 is competitive by using a Ca2+ imaging assay. Concomitant addition of a TRP receptor antagonist, spantide I, reduced the responses of BNGR-A24 not only to TK-4 but also to ITPL. The results of a binding assay using fluorescent-labeled BNGR-A24 and ligands demonstrated that the binding of ITPL to BNGR-A24 was inhibited by TK-4 as well as by spantide I, and vice versa. In addition, the ITPL-induced increase in cGMP levels of BNGR-A24-expressing BmN cells was suppressed by the addition of excess TK-4 or spantide I. The intracellular levels of cAMP and cGMP, as second messenger candidates of the TRP signaling, were not altered by the five TRPs, suggesting that these peptides act via different signaling pathways from cAMP and cGMP signaling at least in BmN cells. Taken together, the present findings suggest that ITPL and TRPs are endogenous orthosteric ligands of BNGR-A24 that may activate discrete signaling pathways. This receptor, which shares orthosteric ligands, may constitute an important model for studying ligand-biased signaling.

Lymphatic deletion of calcitonin receptor–like receptor exacerbates intestinal inflammation

Science.gov (United States)

Davis, Reema B.; Kechele, Daniel O.; Blakeney, Elizabeth S.; Pawlak, John B.

2017-01-01

Lymphatics play a critical role in maintaining gastrointestinal homeostasis and in the absorption of dietary lipids, yet their roles in intestinal inflammation remain elusive. Given the increasing prevalence of inflammatory bowel disease, we investigated whether lymphatic vessels contribute to, or may be causative of, disease progression. We generated a mouse model with temporal and spatial deletion of the key lymphangiogenic receptor for the adrenomedullin peptide, calcitonin receptor–like receptor (Calcrl), and found that the loss of lymphatic Calcrl was sufficient to induce intestinal lymphangiectasia, characterized by dilated lacteals and protein-losing enteropathy. Upon indomethacin challenge, Calcrlfl/fl/Prox1-CreERT2 mice demonstrated persistent inflammation and failure to recover and thrive. The epithelium and crypts of Calcrlfl/fl/Prox1-CreERT2 mice exhibited exacerbated hallmarks of disease progression, and the lacteals demonstrated an inability to absorb lipids. Furthermore, we identified Calcrl/adrenomedullin signaling as an essential upstream regulator of the Notch pathway, previously shown to be critical for intestinal lacteal maintenance and junctional integrity. In conclusion, lymphatic insufficiency and lymphangiectasia caused by loss of lymphatic Calcrl exacerbates intestinal recovery following mucosal injury and underscores the importance of lymphatic function in promoting recovery from intestinal inflammation. PMID:28352669

Binding and transepithelial transport of immunoglobulins by intestinal M cells: demonstration using monoclonal IgA antibodies against enteric viral proteins

OpenAIRE

1989-01-01

M cells of intestinal epithelia overlying lymphoid follicles endocytose luminal macromolecules and microorganisms and deliver them to underlying lymphoid tissue. The effect of luminal secretory IgA antibodies on adherence and transepithelial transport of antigens and microorganisms by M cells is unknown. We have studied the interaction of monoclonal IgA antibodies directed against specific enteric viruses, or the hapten trinitrophenyl (TNP), with M cells. To produce monospecific IgA antibodie...

Pharmacologic properties, metabolism, and disposition of linaclotide, a novel therapeutic peptide approved for the treatment of irritable bowel syndrome with constipation and chronic idiopathic constipation.

Science.gov (United States)

Busby, Robert W; Kessler, Marco M; Bartolini, Wilmin P; Bryant, Alexander P; Hannig, Gerhard; Higgins, Carolyn S; Solinga, Robert M; Tobin, Jenny V; Wakefield, James D; Kurtz, Caroline B; Currie, Mark G

2013-01-01

Linaclotide, a potent guanylate cyclase C agonist, is a therapeutic peptide approved in the United States for the treatment of irritable bowel syndrome with constipation and chronic idiopathic constipation. We present for the first time the metabolism, degradation, and disposition of linaclotide in animals and humans. We examined the metabolic stability of linaclotide in conditions that mimic the gastrointestinal tract and characterized the metabolite MM-419447 (CCEYCCNPACTGC), which contributes to the pharmacologic effects of linaclotide. Systemic exposure to these active peptides is low in rats and humans, and the low systemic and portal vein concentrations of linaclotide and MM-419447 observed in the rat confirmed both peptides are minimally absorbed after oral administration. Linaclotide is stable in the acidic environment of the stomach and is converted to MM-419447 in the small intestine. The disulfide bonds of both peptides are reduced in the small intestine, where they are subsequently proteolyzed and degraded. After oral administration of linaclotide, intestinal loops, increased intraluminal cGMP, and caused a dose-dependent acceleration in gastrointestinal transit. These results demonstrate the importance of the active metabolite in contributing to linaclotide's pharmacology.

Intestinal epithelial barrier function and tight junction proteins with heat and exercise

DEFF Research Database (Denmark)

Dokladny, Karol; Zuhl, Micah N; Moseley, Pope L

2016-01-01

A single layer of enterocytes and tight junctions (intercellular multiprotein complexes) form the intestinal epithelial barrier that controls transport of molecules through transcellular and paracellular pathways. A dysfunctional or "leaky" intestinal tight junction barrier allows augmented perme...

Role of luminal nutrients and endogenous GLP-2 in intestinal adaptation to mid-small bowel resection

DEFF Research Database (Denmark)

Dahly, Elizabeth M; Gillingham, Melanie B; Guo, Ziwen

2003-01-01

To elucidate the role of luminal nutrients and glucagon-like peptide-2 (GLP-2) in intestinal adaptation, rats were subjected to 70% midjejunoileal resection or ileal transection and were maintained with total parenteral nutrition (TPN) or oral feeding. TPN rats showed small bowel mucosal hyperpla......To elucidate the role of luminal nutrients and glucagon-like peptide-2 (GLP-2) in intestinal adaptation, rats were subjected to 70% midjejunoileal resection or ileal transection and were maintained with total parenteral nutrition (TPN) or oral feeding. TPN rats showed small bowel mucosal...... rats was associated with a significant positive correlation between increases in plasma bioactive GLP-2 and proglucagon mRNA expression in the colon of TPN rats and ileum of orally fed rats. These data support a significant role for endogenous GLP-2 in the adaptive response to mid-small bowel resection...

Teduglutide reduces need for parenteral support among patients with short bowel syndrome with intestinal failure

DEFF Research Database (Denmark)

Jeppesen, Palle B; Pertkiewicz, Marek; Messing, Bernard

2012-01-01

Teduglutide, a glucagon-like peptide 2 analogue, might restore intestinal structural and functional integrity by promoting growth of the mucosa and reducing gastric emptying and secretion. These factors could increase fluid and nutrient absorption in patients with short bowel syndrome with intest...

Radioimmunoassay of 1-Deamino-8-D-Arginine Vasopressin and related peptides with special condsideration to their gastrointestinal absorption

International Nuclear Information System (INIS)

Lundin, S.

1986-01-01

A sensitive and specific radioimminoassy for 1-deamino-8-D-arginine vasopressin (DDAVP) was developed. Measurements of the analogue in extracted and non-extracted plasma yielded indentical results, the sensitivity was reduced with non-extracted samples. The assay was validated by correlating DDAVP blood levels to a biologic response (antidiuretic). Dilutions of plasma extracts containing DDAVP were parallel with the standard curve. Fractionations of extracted plasma DDAVP samples on HPLC revealed that immunoreactivity eluted as standard DDAVP. Prolonged infusion of DDAVP in rats did not alter pituitary secretion of oxytocin and vasopressin and urine osmolatity and volume changes were modest. DDAVP was absorbed from the gastrointestinal tract of humans, rats, rabbits and dogs in quantities sufficient to induce a biological response. Peak plasma concentrations were reached between 30-90 min after peptide administration. By the use of an in vitro model, the everted rat intestine, the transmucosal passage of a number of vasopressin analogues were tested. There was no clear-cut correlation between hydrophobicity and intestinal transport rates. Metabolic inhibitors and N/sub2/ did not decrease DDAVP transport. No transport maximum could be demonstrated over a 10/sup4/ fold concentration range. The distribution volume of /sup3/H-polyethyleneglycol was greater. then that of DDAVP in mucosal flakes. There was a close correlation between immunoassayable DDAVP levels and those found after HPLC analyses. It is proposed that DDAVP absorption occurs mainly by passive diffusion. The bioavailability of perorally ingested DDAVP in humans was about 1 percent. Minor amounts were excreted in urine

A dose-equivalent comparison of the effects of continuous subcutaneous glucagon-like peptide 2 (GLP-2) infusions versus meal related GLP-2 injections in the treatment of short bowel syndrome (SBS) patients

DEFF Research Database (Denmark)

Naimi, R M; Madsen, K B; Askov-Hansen, C

2013-01-01

Glucagon-like peptide 2 (GLP-2), secreted endogenously from L-cells in the distal bowel in relation to meals, modulates intestinal absorption by adjusting gastric emptying and secretion and intestinal growth. Short bowel syndrome (SBS) patients with distal intestinal resections have attenuated...

Short Bowel Patients Treated for Two Years with Glucagon-Like Peptide 2: Effects on Intestinal Morphology and Absorption, Renal Function, Bone and Body Composition, and Muscle Function

Directory of Open Access Journals (Sweden)

P. B. Jeppesen

2009-01-01

Full Text Available Background and aims. In a short-term study, Glucagon-like peptide 2 (GLP-2 has been shown to improve intestinal absorption in short bowel syndrome (SBS patients. This study describes longitudinal changes in relation to GLP-2 treatment for two years. Methods. GLP-2, 400 micrograms, s.c.,TID, were offered, to eleven SBS patients keeping parenteral support constant. 72-hour nutritional balance studies were performed at baseline, weeks 13, 26, 52 during two years intermitted by an 8-week washout period. In addition, mucosal morphometrics, renal function (by creatinine clearance, body composition and bone mineral density (by DEXA, biochemical markers of bone turnover (by s-CTX and osteocalcin, PTH and vitamin D, and muscle function (NMR, lungfunction, exercise test were measured. Results. GLP-2 compliance was >93%. Three of eleven patients did not complete the study. In the remaining 8 patients, GLP-2 significantly reduced the fecal wet weight from approximately 3.0 to approximately 2.0 kg/day. This was accompanied by a decline in the oral wet weight intake, maintaining intestinal wet weight absorption and urinary weight constant. Renal function improved. No significant changes were demonstrated in energy intake or absorption, and GLP-2 did not significantly affect mucosal morphology, body composition, bone mineral density or muscle function. Conclusions. GLP-2 treatment reduces fecal weight by approximately 1000 g/d and enables SBS patients to maintain their intestinal fluid and electrolyte absorption at lower oral intakes. This was accompanied by a 28% improvement in creatinine clearance.

123I labelled vasoactive intestinal peptide: Optimization of the radioiodination method, in vivo and in vitro assays

International Nuclear Information System (INIS)

Pozzi, O.R.; Sajaroff, E.O.; Edreira, M.; Gomez, S.I.; Manzini, A.

2002-01-01

In the framework of the CRP, our country has worked on the optimization of synthesis, quality control, in vitro and in vivo evaluation of 123 I radiopharmaceuticals based on peptides. We have worked on selective labelling procedures using prosthetic groups with the goal to create a strong carbon-halogen bond, which will be resistant to in vivo dehalogenation and other catabolic processes. The method utilizes the labelling agent, reactive with ε-amino lysine groups, N-succinimidyl 3-iodobenzoate. This conjugation agent was radiolabelled by using an organometallic intermediate to facilitate the reaction. The organometallic N-succinimidyl 3-(tri-nbutylstannyl) benzoate (ATE) was made in a three-step synthesis pathway. The yields for the reactions of this synthetic pathway were: 56.4% for the first reaction, 67% for the second, and 58% for the ATE (469 mg, 0.92 mmol). Because of only 0.1 μmol of ATE is needed for the labelling of peptides, from one batch of organic synthesis we obtained ATE to make more than 9000 labelling. The N-succinimidyl 3-(tri-n-butylstannyl) benzoate (ATE) was radiolabelled in 55-85% radiochemical yield to obtain the N-succinimidyl 3-iodobenzoate ( [ 131 I]SIB ). Parameters like reactive concentration and isolation method of the labelling agent were studied. The labelling agent [ 131 I]SIB was subsequently conjugated to a human IgG and a peptide. A chemotactic peptide was used as a model peptide. A potent chemotactic peptide N-formyl-norleucyl-leucyl-phenylalanyl-norleucyltyrosyl- lysine (fNleLFNleYK) was derivatized by reaction with the labelling agent in 59-75% of radiochemical yield. This derivatized peptide bound specifically to human polymorphonuclear leukocytes in vitro and exhibited biological activity in a superoxide production assay. Binding affinity IC 50 : 36 nM, in the displacing of [ 3 H]fMLF binding, and IC 50 : 68 nM, in the displacing of the fNleLFNleYK-[ 131 I]SIB conjugate, for the derivatized peptide were obtained. Because

Enhancing the intestinal membrane permeability of zanamivir: a carrier mediated prodrug approach.

Science.gov (United States)

Gupta, Sheeba Varghese; Gupta, Deepak; Sun, Jing; Dahan, Arik; Tsume, Yasuhiro; Hilfinger, John; Lee, Kyung-Dall; Amidon, Gordon L

2011-12-05

The purpose of this study was to improve the membrane permeability and oral absorption of the poorly permeable anti-influenza agent, zanamivir. The poor oral bioavailability is attributed to the high polarity (cLogP ∼ -5) resulting from the polar and zwitterionic nature of zanamivir. In order to improve the permeability of zanamivir, prodrugs with amino acids were developed to target the intestinal membrane transporter, hPepT1. Several acyloxy ester prodrugs of zanamivir conjugated with amino acids were synthesized and characterized. The prodrugs were evaluated for their chemical stability in buffers at various pHs and for their transport and tissue activation by enzymes. The acyloxy ester prodrugs of zanamivir were shown to competitively inhibit [(3)H]Gly-Sar uptake in Caco-2 cells (IC(50): 1.19 ± 0.33 mM for L-valyl prodrug of zanamivir). The L-valyl prodrug of zanamivir exhibited ∼3-fold higher uptake in transfected HeLa/hPepT1 cells compared to wild type HeLa cells, suggesting, at least in part, carrier mediated transport by the hPepT1 transporter. Further, enhanced transcellular permeability of prodrugs across Caco-2 monolayer compared to the parent drug (P(app) = 2.24 × 10(-6) ± 1.33 × 10(-7) cm/s for L-valyl prodrug of zanamivir), with only parent zanamivir appearing in the receiver compartment, indicates that the prodrugs exhibited both enhanced transport and activation in intestinal mucosal cells. Most significantly, several of these prodrugs exhibited high intestinal jejunal membrane permeability, similar to metoprolol, in the in situ rat intestinal perfusion system, a system highly correlated with human jejunal permeability. In summary, this mechanistic targeted prodrug strategy, to enhance oral absorption via intestinal membrane carriers such as hPepT1, followed by activation to parent drug (active pharmaceutical ingredient or API) in the mucosal cell, significantly improves the intestinal epithelial cell permeability of zanamivir and has the

Differential proteiomic analysis of mouse intestinal epithelium irradiated by γ-ray

International Nuclear Information System (INIS)

Zhang Bo; Su Yongping; Liu Xiaohong; Ai Guoping; Ran Xinze; Wei Yongjiang; Wang Junping; Cheng Tianmin

2003-01-01

Objective: For elucidating the molecular mechanism of reconstruction of intestinal epithelium damaged by ionizing radiation, the proteomes of murine intestinal epithelium from normal and irradiated mice were compared by 2-D electrophoresis. Methods: Histopathologic sections of whole small intestine made from BALB/c mice 3 h and 72 h after total-body irradiation were stained with hematoxylin-eosin. Intestinal epithelial cells were isolated from normal and irradiated mice. The total protein samples prepared by one-step method were used in 2-D electrophoresis, the protein maps were compared and the differential spots were detected with PDQuest analysis software. Twenty-eight different spots were cut off from the gels, digested in gel with trypsin, measured with MALDI-TOF-MS and searched in database. Results: Small intestinal epithelium was damaged as early as 3 h after irradiation, and reconstructed 72 h later. After Coomassie-staining, the 2-DE image analysis by PDQuest software detected 638 ± 39 protein spots in normal mice group, 566 ± 32 spots in 3 hours post irradiation group, and 591 ± 29 spots in 3 days post irradiation group. The 2-DE images showed that proteomes of intestinal epithelium were altered with γ-irradiation. The proteins identified by peptide mass fingerprinting involved in cellular events, including signal transduction, metabolism and oxidative stress responses. Conclusions: Gamma-irradiation can induce the protein expression of intestinal epithelium. The technique of 2-D electrophoresis is a useful tool in the study of molecular mechanism of radiation damage

Impact of transporters in oral absorption

DEFF Research Database (Denmark)

Gram, Luise Kvisgaard; Rist, Gerda Marie; Steffansen, Bente

2009-01-01

A key determinant for oral bioavailability of a drug candidate is the intestinal epithelial permeation of the drug candidate. This intestinal permeation may be affected by interactions on membrane transporters expressed in the intestinal epithelial cells. The purpose of the present study...

Early life thermal stress: Impact on future thermotolerance, stress response, behavior, and intestinal morphology in piglets exposed to a heat stress challenge during simulated transport

Science.gov (United States)

Study objectives were to evaluate the impact of early life thermal stress (ELTS) on thermoregulation, stress, and intestinal health of piglets subjected to a future heat stress (HS) challenge during simulated transport. Approximately 7 d after farrowing, 12 first parity gilts and their litters were ...

Influence of structural and surface properties of whey-derived peptides on zinc-chelating capacity, and in vitro gastric stability and bioaccessibility of the zinc-peptide complexes.

Science.gov (United States)

Udechukwu, M Chinonye; Downey, Brianna; Udenigwe, Chibuike C

2018-02-01

Gastrointestinal stability of zinc-peptide complexes is essential for zinc delivery. As peptide surface charge can influence their metal complex stability, we evaluated the zinc-chelating capacity and stability of zinc complexes of whey protein hydrolysates (WPH), produced with Everlase (WPH-Ever; ζ-potential, -39mV) and papain (WPH-Pap; ζ-potential, -7mV), during simulated digestion. WPH-Ever had lower amount of zinc-binding amino acids but showed higher zinc-chelating capacity than WPH-Pap. This is attributable to the highly anionic surface charge of WPH-Ever for electrostatic interaction with zinc. Release of zinc during peptic digestion was lower for WPH-Ever-zinc, and over 50% of zinc remained bound in both peptide complexes after peptic-pancreatic digestion. Fourier transform infrared spectroscopy suggests the involvement of carboxylate ion, and sidechain carbon-oxygen of aspartate/glutamate and serine/threonine in zinc-peptide complexation. The findings indicate that strong zinc chelation can promote gastric stability and impede intestinal release, for peptides intended for use as dietary zinc carriers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of gastric inhibitory polypeptide, glucagon-like peptide-1 and glucagon-like peptide-1 receptor agonists on Bone Cell Metabolism

DEFF Research Database (Denmark)

Hansen, Morten S S; Tencerova, Michaela; Frølich, Jacob

2018-01-01

The relationship between gut and skeleton is increasingly recognised as part of the integrated physiology of the whole organism. The incretin hormones gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are secreted from the intestine in response to nutrient intake and exhibi......-clinical investigations, clinical trials are needed to clarify if similar effects are present and clinically relevant in humans. This article is protected by copyright. All rights reserved....

Reducing small intestinal permeability attenuates colitis in the IL10 gene-deficient mouse

Science.gov (United States)

Arrieta, M C; Madsen, K; Doyle, J; Meddings, J

2008-01-01

Background: Defects in the small intestinal epithelial barrier have been associated with inflammatory bowel disease but their role in the causation of disease is still a matter of debate. In some models of disease increased permeability appears to be a very early event. The interleukin 10 (IL10) gene-deficient mouse spontaneously develops colitis after 12 weeks of age. These mice have been shown to have increased small intestinal permeability that appears early in life. Furthermore, the development of colitis is dependent upon luminal agents, as animals do not develop disease if raised under germ-free conditions. Aims: To determine if the elevated small bowel permeability can be prevented, and if by doing so colonic disease is prevented or attenuated. Methods: IL10 gene-deficient (IL10−/−) mice) were treated with AT-1001 (a zonulin peptide inhibitor), a small peptide previously demonstrated to reduce small intestinal permeability. Small intestinal permeability was measured, in vivo, weekly from 4 to 17 weeks of age. Colonic disease was assessed at 8 weeks in Ussing chambers, and at 17 weeks of age inflammatory cytokines and myeloperoxidase were measured in the colon. Colonic permeability and histology were also endpoints. Results: Treated animals showed a marked reduction in small intestinal permeability. Average area under the lactulose/mannitol time curve: 5.36 (SE 0.08) in controls vs 3.97 (SE 0.07) in the high-dose AT-1001 group, p<0.05. At 8 weeks of age there was a significant reduction of colonic mucosal permeability and increased electrical resistance. By 17 weeks of age, secretion of tumour necrosis factor α (TNFα) from a colonic explant was significantly lower in the treated group (25.33 (SE 4.30) pg/mg vs 106.93 (SE 17.51) pg/ml in controls, p<0.01). All other markers also demonstrated a clear reduction of colitis in the treated animals. Additional experiments were performed which demonstrated that AT-1001 was functionally active only in the small

Structured triglyceride vehicles for oral delivery of halofantrine: examination of intestinal lymphatic transport and bioavailability in conscious rats.

Science.gov (United States)

Holm, René; Porter, Christopher J H; Müllertz, Anette; Kristensen, Henning G; Charman, William N

2002-09-01

To compare the influence of triglyceride vehicle intramolecular structure on the intestinal lymphatic transport and systemic absorption of halofantrine in conscious rats. Conscious, lymph cannulated and nonlymph cannulated rats were dosed orally with three structurally different triglycerides; sunflower oil, and two structured triglycerides containing different proportion and position of medium-(M) and long-chain (L) fatty acids on the glycerol backbone. The two structured triglycerides were abbreviated MLM and LML to reflect the structural position on the glycerol. The concentration of halofantrine in blood and lymph samples was analyzed by HPLC. Both the lymphatic transport and the total absorption of halofantrine were enhanced by the use the MLM triglyceride. The estimated total absorption of halofantrine in the lymph cannulated animals was higher than in the nonlymph cannulated animals, and this was most pronounced for the animals dosed with the structured triglycerides. Using MLM as vehicle increases the portal absorption of halofantrine and results in similar lymphatic transport levels when compared to sunflower oil. Total absorption when assessed as absorption in the blood plus lymphatic transport for halofantrine after administration in the MLM triglyceride was higher than after administration in sunflower oil.

Expression of receptors for gut peptides in human pancreatic adenocarcinoma and tumour-free pancreas

NARCIS (Netherlands)

Tang, C.; Biemond, I.; Offerhaus, G. J.; Verspaget, W.; Lamers, C. B.

1997-01-01

Gut hormones that modulate the growth of normal pancreas may also modulate the growth of cancers originating from pancreas. This study visualized and compared the receptors for cholecystokinin (CCK), bombesin (BBS), secretin and vasoactive intestinal peptide (VIP) in tumour-free tissue sections of

The in vivo disposition and in vitro transmembrane transport of two model radiometabolites of DOTA-conjugated receptor-specific peptides labelled with (177) Lu.

Science.gov (United States)

Volková, Marie; Mandíková, Jana; Bárta, Pavel; Navrátilová, Lucie; Lázníčková, Alice; Trejtnar, František

2015-01-01

In vivo metabolism of the radiolabelled receptor-specific peptides has been described; however, information regarding the pharmacokinetic behaviour of the degradation products within the body is very scarce. The present study was designed to obtain new knowledge on the disposition and elimination of low-molecular radiometabolites of receptor-specific peptides in the organism and to reveal the potential involvement of selected membrane transport mechanisms in the cellular uptake of radiometabolites, especially in the kidney. The study compared pharmacokinetics of two radiometabolites: a final metabolite of somatostatin analogues, (177)Lu-DOTA-DPhe, and a tripeptide metabolite of (177)Lu-DOTA-minigastrin 11, (177)Lu-DOTA-DGlu-Ala-Tyr. Their pharmacokinetics was compared with that of respective parent (177)Lu-radiopeptide. Both radiometabolites exhibited relative rapid clearing from most body tissues in rats in vivo along with predominant renal excretion. The long-term renal retention of the smaller radiometabolite (177)Lu-DOTA-DPhe was lower than that of (177)Lu-DOTA-DGlu-Ala-Tyr. An uptake of (177)Lu-DOTA-DPhe by human renal influx transporter organic cation transporter 2 was found in vitro in a cellular model. The study brings the first experimental data on the in vivo pharmacokinetics of radiometabolites of receptor-specific somatostatin and gastrin analogues. The found results may indicate a negative correlation between the degree of decomposition of the parent peptide chain and the renal retention of the metabolite. Copyright © 2015 John Wiley & Sons, Ltd.

Effects of chronic glucagon-like peptide-2 therapy during weaning in neonatal pigs

DEFF Research Database (Denmark)

Sigalet, David L; de Heuvel, Elaine; Wallace, Laurie

2014-01-01

BACKGROUND: The enteroendocrine hormone glucagon like peptide-2 (GLP-2) and its ligands are under development as therapeutic agents for a variety of intestinal pathologies. A number of these conditions occur in neonates and infants, and thus a detailed understanding of the effects of GLP-2 during...

Epithelial-derived IL-33 promotes intestinal tumorigenesis in Apc Min/+ mice.

Science.gov (United States)

He, Zhengxiang; Chen, Lili; Souto, Fabricio O; Canasto-Chibuque, Claudia; Bongers, Gerold; Deshpande, Madhura; Harpaz, Noam; Ko, Huaibin M; Kelley, Kevin; Furtado, Glaucia C; Lira, Sergio A

2017-07-14

Increased expression of Interleukin (IL)-33 has been detected in intestinal samples of patients with ulcerative colitis, a condition associated with increased risk for colon cancer, but its role in the development of colorectal cancer has yet to be fully examined. Here, we investigated the role of epithelial expressed IL-33 during development of intestinal tumors. IL-33 expression was detected in epithelial cells in colorectal cancer specimens and in the Apc Min/+ mice. To better understand the role of epithelial-derived IL-33 in the intestinal tumorigenesis, we generated transgenic mice expressing IL-33 in intestinal epithelial cells (V33 mice). V33 Apc Min/+ mice, resulting from the cross of V33 with Apc Min/+ mice, had increased intestinal tumor burden compared with littermate Apc Min/+ mice. Consistently, Apc Min/+ mice deficient for IL-33 receptor (ST2), had reduced polyp burden. Mechanistically, overexpression of IL-33 promoted expansion of ST2 + regulatory T cells, increased Th2 cytokine milieu, and induced alternatively activated macrophages in the gut. IL-33 promoted marked changes in the expression of antimicrobial peptides, and antibiotic treatment of V33 Apc Min/+ mice abrogated the tumor promoting-effects of IL-33 in the colon. In conclusion, elevated IL-33 signaling increases tumor development in the Apc Min/+ mice.

In vitro analysis of the bioavailability of six metals via the gastro-intestinal tract of the rainbow trout (Oncorhynchus mykiss)

Energy Technology Data Exchange (ETDEWEB)

Ojo, Adeola A. [Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1 (Canada)]. E-mail: abosede_07@hotmail.com; Wood, Chris M. [Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4K1 (Canada)]. E-mail: woodcm@mcmaster.ca

2007-06-05

An in vitro gut sac technique was used to compare the uptake rates of essential (copper, zinc and nickel) and non-essential metals (silver, cadmium and lead) at 50 {mu}mol L{sup -1} each (a typical nutritive level in solution in chyme) in the luminal saline in four sections of the gastro-intestinal tract (stomach, anterior, mid and posterior intestines) of the freshwater rainbow trout. Cu, Zn, Cd and Ag exhibited similar regional patterns: on an area-specific basis, uptake rates for these metals were highest in the anterior intestine, lowest in the stomach, and approximately equal in the mid and posterior intestinal segments. When these rates were converted to a whole animal basis, the predominance of the anterior intestine increased because of its greater area, while the contribution of the stomach rose slightly to approach those of the mid and posterior intestines. However, for Pb and Ni, area-specific and whole organism transport rates were greatest in the mid (Pb) and posterior (Ni) intestines. Surprisingly, total transport rates did not differ appreciably among the essential and non-essential metals, varying only from 0.025 (Ag) to 0.050 nmol g{sup -1} h{sup -1} (Ni), suggesting that a single rate constant can be applied for risk assessment purposes. These rates were generally comparable to previously reported uptake rates from waterborne exposures conducted at concentrations 1-4 orders of magnitude lower, indicating that both routes are likely important, and that gut transporters operate with much lower affinity than gill transporters. Except for Ni, more metal was bound to mucus and/or trapped in the mucosal epithelium than was transported into the blood space in every compartment except the anterior intestine, where net transport predominated. Overall, mucus binding was a significant predictor of net transport rate for every metal except Cd, and the strongest relationship was seen for Pb.

In vivo analysis of intestinal permeability following hemorrhagic shock

Science.gov (United States)

Alsaigh, Tom; Chang, Marisol; Richter, Michael; Mazor, Rafi; Kistler, Erik B

2015-01-01

AIM: To determine the time course of intestinal permeability changes to proteolytically-derived bowel peptides in experimental hemorrhagic shock. METHODS: We injected fluorescently-conjugated casein protein into the small bowel of anesthetized Wistar rats prior to induction of experimental hemorrhagic shock. These molecules, which fluoresce when proteolytically cleaved, were used as markers for the ability of proteolytically cleaved intestinal products to access the central circulation. Blood was serially sampled to quantify the relative change in concentration of proteolytically-cleaved particles in the systemic circulation. To provide spatial resolution of their location, particles in the mesenteric microvasculature were imaged using in vivo intravital fluorescent microscopy. The experiments were then repeated using an alternate measurement technique, fluorescein isothiocyanate (FITC)-labeled dextrans 20, to semi-quantitatively verify the ability of bowel-derived low-molecular weight molecules (< 20 kD) to access the central circulation. RESULTS: Results demonstrate a significant increase in systemic permeability to gut-derived peptides within 20 min after induction of hemorrhage (1.11 ± 0.19 vs 0.86 ± 0.07, P < 0.05) compared to control animals. Reperfusion resulted in a second, sustained increase in systemic permeability to gut-derived peptides in hemorrhaged animals compared to controls (1.2 ± 0.18 vs 0.97 ± 0.1, P < 0.05). Intravital microscopy of the mesentery also showed marked accumulation of fluorescent particles in the microcirculation of hemorrhaged animals compared to controls. These results were replicated using FITC dextrans 20 [10.85 ± 6.52 vs 3.38 ± 1.11 fluorescent intensity units (× 105, P < 0.05, hemorrhagic shock vs controls)], confirming that small bowel ischemia in response to experimental hemorrhagic shock results in marked and early increases in gut membrane permeability. CONCLUSION: Increased small bowel permeability in hemorrhagic

The small intestine and irritable bowel syndrome (IBS): a batch process model.

Science.gov (United States)

Dobson, Brian C

2008-11-01

Faults in a batch process model of the small intestine create the symptoms of all types of irritable bowel syndrome. The model has three sequential processing sections corresponding to the natural divisions of the intestine. It is governed by a brain controller that is divided into four sub-controllers, each with a unique neurotransmitter. Each section has a sub-controller to manage transport. Sensors in the walls of the intestine provide input and output goes to the muscles lining the walls of the intestine. The output controls the speed of the food soup, moves it in both directions, mixes it, controls absorption, and transfers it to the next section at the correct speed (slow). The fourth sub-controller manages the addition of chemicals. It obtains input from the first section of the process via the signalling hormone Cholecystokinin and sends output to the muscles that empty the gall bladder and pancreas. The correct amounts of bile salts and enzymes are then added to the first section. The sub-controllers produce output only when input is received. When output is missing the enteric nervous system applies a default condition. This default condition normally happens when no food is in the intestine. If food is in the intestine and a transport sub-controller fails to provide output then the default condition moves the food soup to the end of that section. The movement is in one direction only (forward), at a speed dependent on the amount and type of fibre present. Cereal, bean and vegetable fibre causes high speeds. This default high speed transport causes irritable bowel syndrome. A barrier is created when a section moving fast at the default speed, precedes a section controlled by a transport sub-controller. Then the sub-controller constricts the intestine to stop the fast flow. The barrier causes constipation, cramping, and bloating. Diarrhoea results when the section terminating the process moves at the fast default speed. Two problems can occur to prevent

Angiotensin receptors and angiotensin I-converting enzyme in rat intestine

International Nuclear Information System (INIS)

Duggan, K.A.; Mendelsohn, F.A.; Levens, N.R.

1989-01-01

The purpose of this study was to map the distribution of angiotensin II (ANG II) receptors and ANG I-converting enzyme (ACE) in rat intestine. ANG II binding sites were visualized by in vitro autoradiography using iodinated [Sar1, Ile8]ANG II. The distribution of ACE was mapped using an iodinated derivative of lisinopril. Male Sprague-Dawley rats were killed and the interior of the whole intestine washed with ice-cold saline. Segments of duodenum, jejunum, ileum, and colon were quickly frozen in a mixture of isopentane and dry ice. Twenty-micron frozen sections were thaw-mounted onto gelatin-coated slides, incubated with either ligand, and exposed to X-ray film. After exposure and subsequent development, the films were quantitated by computerized densitometry. ANG II receptors were most dense in the colon, followed by the ileum, duodenum, and jejunum. Within each segment of intestine, specific ANG II binding sites were localized exclusively to the muscularis. In contrast, ACE was present in both the mucosa and the muscularis. The colocalization of ANG II receptors and ACE may suggest a role for locally generated ANG II in the control of intestinal function. The luminal orientation of ACE in the mucosa of the small intestine may suggest that at this site ACE serves primarily to hydrolyze dietary peptides

Correlation between oral drug absorption in humans and apparent drug permeability coefficients in human intestinal epithelial (Caco-2) cells

International Nuclear Information System (INIS)

Artursson, P.; Karlsson, J.

1991-01-01

Monolayers of a well differentiated human intestinal epithelial cell line, Caco-2, were used as a model to study passive drug absorption across the intestinal epithelium. Absorption rate constants (expressed as apparent permeability coefficients) were determined for 20 drugs and peptides with different structural properties. The permeability coefficients ranged from approximately 5 x 10 - 8 to 5 x 10 - 5 cm/s. A good correlation was obtained between data on oral absorption in humans and the results in the Caco-2 model. Drugs that are completely absorbed in humans had permeability coefficients greater than 1 x 10 - 6 cm/s. Drugs that are absorbed to greater than 1% but less than 100% had permeability coefficients of 0.1-1.0 x 10 - 6 cm/s while drugs and peptides that are absorbed to less than 1% had permeability coefficients of less than or equal to 1 x 10 - 7 cm/s. The results indicate that Caco-2 monolayers can be used as a model for studies on intestinal drug absorption

High Expression of UGT1A1/1A6 in Monkey Small Intestine: Comparison of Protein Expression Levels of Cytochromes P450, UDP-Glucuronosyltransferases, and Transporters in Small Intestine of Cynomolgus Monkey and Human.

Science.gov (United States)

Akazawa, Takanori; Uchida, Yasuo; Miyauchi, Eisuke; Tachikawa, Masanori; Ohtsuki, Sumio; Terasaki, Tetsuya

2018-01-02

Cynomolgus monkeys have been widely used for the prediction of drug absorption in humans. The purpose of this study was to clarify the regional protein expression levels of cytochromes P450 (CYPs), UDP-glucuronosyltransferases (UGTs), and transporters in small intestine of cynomolgus monkey using liquid chromatography-tandem mass spectrometry, and to compare them with the corresponding levels in human. UGT1A1 in jejunum and ileum were >4.57- and >3.11-fold and UGT1A6 in jejunum and ileum were >16.1- and >8.57-fold, respectively, more highly expressed in monkey than in human. Also, jejunal expression of monkey CYP3A8 (homologue of human CYP3A4) was >3.34-fold higher than that of human CYP3A4. Among apical drug efflux transporters, BCRP showed the most abundant expression in monkey and human, and the expression levels of BCRP in monkey and human were >1.74- and >1.25-fold greater than those of P-gp and >2.76- and >4.50-fold greater than those of MRP2, respectively. These findings should be helpful to understand species differences of the functions of CYPs, UGTs, and transporters between monkey and human. The UGT1A1/1A6 data would be especially important because it is difficult to identify isoforms responsible for species differences of intestinal glucuronidation by means of functional studies due to overlapping substrate specificity.

Absorption of l-methionine from the human small intestine

Science.gov (United States)

Schedl, Harold P.; Pierce, Charles E.; Rider, Alan; Clifton, James A.

1968-01-01

Absorption of L-methionine was measured in all parts of the human small intestine using transintestinal intubation and perfusion. In four normal subjects, adsorption was higher in the proximal than in the distal intestine. In two patients with nontropical sprue in relapse, there was a proximal zone of low absorption with higher absorption distally. In all parts of the small intestine, absorption showed rate-limiting kinetics as methionine concentration was increased. In normal subjects, the proximal Km (Michaelis constant) was more than 3 times higher than the distal, which suggests a difference in transport mechanisms between the two segments. PMID:12066784

Biorelevant media resistant co-culture model mimicking permeability of human intestine.

Science.gov (United States)

Antoine, Delphine; Pellequer, Yann; Tempesta, Camille; Lorscheidt, Stefan; Kettel, Bernadette; Tamaddon, Lana; Jannin, Vincent; Demarne, Frédéric; Lamprecht, Alf; Béduneau, Arnaud

2015-03-15

Cell culture models are currently used to predict absorption pattern of new compounds and formulations in the human gastro-intestinal tract (GIT). One major drawback is the lack of relevant apical incubation fluids allowing mimicking luminal conditions in the GIT. Here, we suggest a culture model compatible with biorelevant media, namely Fasted State Simulated Intestinal Fluid (FaSSIF) and Fed State Simulated Intestinal Fluid (FeSSIF). Co-culture was set up from Caco-2 and mucus-secreting HT29-MTX cells using an original seeding procedure. Viability and cytotoxicity assays were performed following incubation of FeSSIF and FaSSIF with co-culture. Influence of biorelevant fluids on paracellular permeability or transporter proteins were also evaluated. Results were compared with Caco-2 and HT29-MTX monocultures. While Caco-2 viability was strongly affected with FeSSIF, no toxic effect was detected for the co-cultures in terms of viability and lactate dehydrogenase release. The addition of FeSSIF to the basolateral compartment of the co-culture induced cytotoxic effects which suggested the apical mucus barrier being cell protective. In contrast to FeSSIF, FaSSIF induced a slight increase of the paracellular transport and both tested media inhibited partially the P-gp-mediated efflux in the co-culture. Additionally, the absorptive transport of propranolol hydrochloride, a lipophilic β-blocker, was strongly affected by biorelevant fluids. This study demonstrated the compatibility of the Caco-2/HT29-MTX model with some of the current biorelevant media. Combining biorelevant intestinal fluids with features such as mucus secretion, adjustable paracellular and P-gp mediated transports, is a step forward to more realistic in-vitro models of the human intestine. Copyright © 2015. Published by Elsevier B.V.

Energetic and frictional effects in the transport of ions in a cyclic peptide nanotube

Energy Technology Data Exchange (ETDEWEB)

Seo, Yongil; Song, Yeon Ho; Hwang, Hyeon Seok [Dept. of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon (Korea, Republic of); Schatz, George C. [Dept. of Chemistry, Northwestern University, Evanston (United States)

2017-01-15

The effects of geometric restraints and frictional parameters on the energetics and dynamics of ion transport through a synthetic ion channel are investigated using molecular dynamics (MD) simulations for several different ions. To do so, potential of mean force profiles and position-dependent diffusion coefficients for Na{sup +}, K{sup +}, Ca{sup 2+}, and Cl{sup −} transport through a simple cyclic peptide nanotube, which is composed of 4× cyclo[−(D-Ala-Glu-D-Ala-Gln){sub 2−}] rings, are calculated via an adaptive biasing force MD simulation method and a Baysian inference/Monte Carlo algorithm. Among the restraints and parameters examined in this work, the radius parameter used in the flat-bottom half-harmonic restraint at the entrance and exit to channel has a great effect on the energetics of ion transport through the variation of entropy in the outside of the channel. The diffusivity profiles for the ions show a strong dependence on the damping coefficient, but the dependence on the coefficient becomes minimal inside the channel, indicating that the most important factor which affects the diffusivity of ions inside the channel is local interactions of ions with the structured channel water molecules through confinement.

Toxicity of Biologically Active Peptides and Future Safety Aspects: An Update.

Science.gov (United States)

Khan, Fazlullah; Niaz, Kamal; Abdollahi, Mohammad

2018-02-18

Peptides are fragments of proteins with significant biological activities. These peptides are encoded in the protein sequence. Initially, such peptides are inactive in their parental form, unless proteolytic enzymes are released. These peptides then exhibit various functions and play a therapeutic role in the body. Besides the therapeutic and physiological activities of peptides, the main purpose of this study was to highlight the safety aspects of peptides. We performed an organized search of available literature using PubMed, Google Scholar, Medline, EMBASE, Reaxys and Scopus databases. All the relevant citations including research and review articles about the toxicity of biologically active peptides were evaluated and gathered in this study. Biological peptides are widely used in the daily routine ranging from food production to the cosmetics industry and also they have a beneficial role in the treatment and prevention of different diseases. These peptides are manufactured by both chemical and biotechnological techniques, which show negligible toxicity, however, some naturally occurring peptides and enzymes may induce high toxicity. Depending upon the demand and expected use in the food or pharmaceutical industry, we need different approaches to acertain the safety of these peptides preferentially through in silico methods. Intestinal wall disruption, erythrocytes and lymphocytes toxicity, free radical production, enzymopathic and immunopathic tissue damage and cytotoxicity due to the consumption of peptides are the main problems in the biological system that lead to various complicated disorders. Therefore, before considering biologically active peptides for food production and for therapeutic purpose, it is first necessary to evaluate the immunogenicity and toxicities of peptides. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Specific efficacy of peptide receptor radionuclide therapy with {sup 177}Lu-octreotate in advanced neuroendocrine tumours of the small intestine

Energy Technology Data Exchange (ETDEWEB)

Sabet, Amir; Dautzenberg, Kristina; Haslerud, Torjan; Aouf, Anas; Sabet, Amin; Biersack, Hans-Juergen [University Hospital, Department of Nuclear Medicine, Bonn (Germany); Simon, Birgit [University Hospital, Department of Radiology, Bonn (Germany); Mayer, Karin [University Hospital, Department of Internal Medicine and Oncology, Bonn (Germany); Ezziddin, Samer [University Hospital, Department of Nuclear Medicine, Bonn (Germany); Saarland University, Department of Nuclear Medicine, Homburg (Germany)

2015-07-15

Increasing evidence supports the value of peptide receptor radionuclide therapy (PRRT) in patients with metastatic neuroendocrine tumours (NET), but there are limited data on its specific efficacy in NET of small intestinal (midgut) origin. This study aims to define the benefit of PRRT with {sup 177}Lu-octreotate for this circumscribed entity derived by a uniformly treated patient cohort. A total of 61 consecutive patients with unresectable, advanced small intestinal NET G1-2 stage IV treated with {sup 177}Lu-octreotate (4 intended cycles at 3-month intervals, mean activity per cycle 7.9 GBq) were analysed. Sufficient tumour uptake on baseline receptor imaging and either documented tumour progression (n = 46) or uncontrolled symptoms (n = 15) were prerequisites for treatment. Response was evaluated according to modified Southwest Oncology Group (SWOG) criteria and additionally with Response Criteria in Solid Tumors (RECIST) 1.1. Assessment of survival was performed using Kaplan-Meier curves and Cox proportional hazards model for uni- and multivariate analyses. Toxicity was assessed according to standardized follow-up laboratory work-up including blood counts, liver and renal function, supplemented with serial {sup 99m}Tc-diethylenetriaminepentaacetic acid (DTPA) clearance measurements. The median follow-up period was 62 months. Reversible haematotoxicity (≥ grade 3) occurred in five patients (8.2 %). No significant nephrotoxicity (≥ grade 3) was observed. Treatment response according to modified SWOG criteria consisted of partial response in 8 (13.1 %), minor response in 19 (31.1 %), stable disease in 29 (47.5 %) and progressive disease in 5 (8.2 %) patients. The disease control rate was 91.8 %. Median progression-free survival (PFS) and overall survival (OS) was 33 [95 % confidence interval (CI) 25-41] and 61 months (95 % CI NA), respectively. Objective response was associated with longer survival (p = 0.005). Independent predictors of shorter PFS were

The cell-specific pattern of cholecystokinin peptides in endocrine cells versus neurons is governed by the expression of prohormone convertases 1/3, 2, and 5/6

DEFF Research Database (Denmark)

Bundgaard, J.R.; Hannibal, J.; Zhu, X.

2008-01-01

Most peptide hormone genes are, in addition to endocrine cells, also expressed in neurons. The peptide hormone cholecystokinin (CCK) is expressed in different molecular forms in cerebral neurons and intestinal endocrine cells. To understand this difference, we examined the roles of the neuroendoc...

The physiology of glucagon-like peptide 1

DEFF Research Database (Denmark)

Holst, Jens Juul

2007-01-01

Glucagon-like peptide 1 (GLP-1) is a 30-amino acid peptide hormone produced in the intestinal epithelial endocrine L-cells by differential processing of proglucagon, the gene which is expressed in these cells. The current knowledge regarding regulation of proglucagon gene expression in the gut...... and in the brain and mechanisms responsible for the posttranslational processing are reviewed. GLP-1 is released in response to meal intake, and the stimuli and molecular mechanisms involved are discussed. GLP-1 is extremely rapidly metabolized and inactivated by the enzyme dipeptidyl peptidase IV even before...... postprandial glucose excursions. It also inhibits gastrointestinal motility and secretion and thus acts as an enterogastrone and part of the "ileal brake" mechanism. GLP-1 also appears to be a physiological regulator of appetite and food intake. Because of these actions, GLP-1 or GLP-1 receptor agonists...

In vivo and In vitro Evaluations of Intestinal Gabapentin Absorption

DEFF Research Database (Denmark)

Larsen, Malte Selch; Frølund, Sidsel; Nøhr, Martha Kampp

2015-01-01

of gabapentin by both in vivo and in vitro investigations METHODS: Pharmacokinetic parameters were determined following a range of intravenous (5-100 mg/kg) and oral doses (10-200 mg/kg) in rats. Transepithelial transport (50 μM-50 mM) and apical uptake of gabapentin (0.01-50 mM) were investigated in Caco-2...... cells. The effect of co-application of the LAT-inhibitor, BCH, and the b(0,+)-substrate, L-lysine, on intestinal transport of gabapentin was evaluated in vivo and in vitro. RESULTS: Gabapentin showed dose-dependent oral absorption kinetics and dose-independent disposition kinetics. Co-application of BCH...... inhibited intestinal absorption in vivo and apical uptake in vitro, whereas no effect was observed following co-application of L-lysine. CONCLUSIONS: The present study shows for the first time that BCH was capable of inhibiting intestinal absorption of gabapentin in vivo. Furthermore, in Caco-2 cell...

Common occurrence of antibacterial agents in human intestinal microbiota

Directory of Open Access Journals (Sweden)

Fatima eDrissi

2015-05-01

Full Text Available Laboratory experiments have revealed many active mechanisms by which bacteria can inhibit the growth of other organisms. Bacteriocins are a diverse group of natural ribosomally-synthesized antimicrobial peptides produced by a wide range of bacteria and which seem to play an important role in mediating competition within bacterial communities. In this study, we have identified and established the structural classification of putative bacteriocins encoded by 317 microbial genomes in the human intestine. On the basis of homologies to available bacteriocin sequences, mainly from lactic acid bacteria, we report the widespread occurrence of bacteriocins across the gut microbiota: 175 bacteriocins were found to be encoded in Firmicutes, 79 in Proteobacteria, 34 in Bacteroidetes and 25 in Actinobacteria. Bacteriocins from gut bacteria displayed wide differences among phyla with regard to class distribution, net positive charge, hydrophobicity and secondary structure, but the α-helix was the most abundant structure. The peptide structures and physiochemical properties of bacteriocins produced by the most abundant bacteria in the gut, the Firmicutes and the Bacteroidetes, seem to ensure low antibiotic activity and participate in permanent intestinal host defence against the proliferation of harmful bacteria. Meanwhile, the potentially harmful bacteria, including the Proteobacteria, displayed highly effective bacteriocins, probably supporting the virulent character of diseases. These findings highlight the eventual role played by bacteriocins in gut microbial competition and their potential place in antibiotic therapy.

Hydrodynamic Impacts on Dissolution, Transport and Absorption from Thousands of Drug Particles Moving within the Intestines

Science.gov (United States)

Behafarid, Farhad; Brasseur, James G.

2017-11-01

Following tablet disintegration, clouds of drug particles 5-200 μm in diameter pass through the intestines where drug molecules are absorbed into the blood. Release rate depends on particle size, drug solubility, local drug concentration and the hydrodynamic environment driven by patterned gut contractions. To analyze the dynamics underlying drug release and absorption, we use a 3D lattice Boltzmann model of the velocity and concentration fields driven by peristaltic contractions in vivo, combined with a mathematical model of dissolution-rate from each drug particle transported through the grid. The model is empirically extended for hydrodynamic enhancements to release rate by local convection and shear-rate, and incorporates heterogeneity in bulk concentration. Drug dosage and solubility are systematically varied along with peristaltic wave speed and volume. We predict large hydrodynamic enhancements (35-65%) from local shear-rate with minimal enhancement from convection. With high permeability boundary conditions, a quasi-equilibrium balance between release and absorption is established with volume and wave-speed dependent transport time scale, after an initial transient and before a final period of dissolution/absorption. Supported by FDA.

Downregulation of hepatic and intestinal ATP-binding-cassette transporters abcg5 and abcg8 expression associated with altered sterol fluxes in rats with streptozotocin-induced diabetes

NARCIS (Netherlands)

Bloks, VW; Bakker-van Waarde, WW; Verkade, HJ; Kema, IP; Havinga, R; Wolters, H; Schaap, FG; Sauer, PJJ; Vink, E; Groen, AK; Kuipers, F

ABSTRACT: P234 Downregulation of Hepatic and Intestinal ATP-Binding-Cassette Transporters Abcg5 and Abcg8 Expression Associated with Altered Sterol Fluxes in Rats with Streptozotocin-Induced Diabetes Vincent W. Bloks, Willie W. Bakker-van Waarde, Henkjan J. Verkade, Ido P. Kema, Rick Havinga, Henk

Small intestinal efflux mediated by MRP2 and BCRP shifts sulfasalazine intestinal permeability from high to low, enabling its colonic targeting.

Science.gov (United States)

Dahan, Arik; Amidon, Gordon L

2009-08-01

Sulfasalazine is characterized by low intestinal absorption, which essentially enables its colonic targeting and therapeutic action. The mechanisms behind this low absorption have not yet been elucidated. The purpose of this study was to investigate the role of efflux transporters in the intestinal absorption of sulfasalazine as a potential mechanism for its low small-intestinal absorption and colonic targeting following oral administration. The effects of P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP) inhibitors on sulfasalazine bidirectional permeability were studied across Caco-2 cell monolayers, including dose-response analysis. Sulfasalazine in vivo permeability was then investigated in the rat jejunum by single-pass perfusion, in the presence vs. absence of inhibitors. Sulfasalazine exhibited 19-fold higher basolateral-to-apical (BL-AP) than apical-to-basolateral (AP-BL) Caco-2 permeability, indicative of net mucosal secretion. MRP2 inhibitors (MK-571 and indomethacin) and BCRP inhibitors [fumitremorgin C (FTC) and pantoprazole] significantly increased AP-BL and decreased BL-AP sulfasalazine Caco-2 transport in a concentration-dependent manner. No effect was observed with the P-gp inhibitors verapamil and quinidine. The IC50 values of the specific MRP2 and BCRP inhibitors MK-571 and FTC on sulfasalazine secretion were 21.5 and 2.0 microM, respectively. Simultaneous inhibition of MRP2 and BCRP completely abolished sulfasalazine Caco-2 efflux. Without inhibitors, sulfasalazine displayed low (vs. metoprolol) in vivo intestinal permeability in the rat model. MK-571 or FTC significantly increased sulfasalazine permeability, bringing it to the low-high permeability boundary. With both MK-571 and FTC present, sulfasalazine displayed high permeability. In conclusion, efflux transport mediated by MRP2 and BCRP, but not P-gp, shifts sulfasalazine permeability from high to low, thereby enabling its

Separation of Peptides with Forward Osmosis Biomimetic Membranes

DEFF Research Database (Denmark)

Bajraktari, Niada; Madsen, Henrik T; Gruber, Mathias Felix

2016-01-01

such as pharmaceuticals. It is crucial in such settings to control the transport over the membrane to avoid losses of valuable compounds, but little is known about the rejection and transport mechanisms of larger biomolecules with often flexible conformations. In this study, transport of two chemically similar peptides...

Leukotriene D4 activates distinct G-proteins in intestinal epithelial cells to regulate stress fibre formation and to generate intracellular Ca2+ mobilisation and ERK1/2 activation

International Nuclear Information System (INIS)

Nielsen, Christian Kamp; Massoumi, Ramin; Sonnerlind, Maria; Sjoelander, Anita

2005-01-01

We have shown that the pro-inflammatory mediator LTD 4 , via its G-protein-coupled receptor CysLT 1 , signals through both pertussis-toxin-sensitive and -insensitive G-proteins to induce various cellular responses. To further characterise the initial step of the different signalling pathways emanating from the CysLT 1 receptor, we transfected intestinal epithelial cells, Int 407, with different mini vectors that each express a specific inhibitory peptide directed against a unique α subunit of a specific heterotrimeric G-protein. Our results revealed that LTD 4 -induced stress fibre formation is inhibited approximately 80% by a vector expressing an inhibitory peptide against the pertussis-toxin-insensitive Gα 12 -protein in intestinal epithelial Int 407 cells. Control experiments revealed that the LPA-induced stress fibre formation, mediated via the Gα 12 -protein in other cell types, was blocked by the same peptide in intestinal Int 407 cells. Furthermore, the CysLT 1 -receptor-mediated calcium signal and activation of the proliferative ERK1/2 kinase are blocked in cells transfected with a vector expressing an inhibitory peptide against the Gα i3 -protein, whereas in cells transfected with an empty ECFP-vector or vectors expressing inhibitory peptides against the Gα i1-2 -, Gα 12 -, Gα R -proteins these signals are not significantly affected. Consequently, the CysLT 1 receptor has the capacity to activate at least two distinctly different heterotrimeric G-proteins that transduce activation of unique downstream cellular events

Oral delivery of peptides and proteins using lipid-based drug delivery systems.

Science.gov (United States)

Li, Ping; Nielsen, Hanne Mørck; Müllertz, Anette

2012-10-01

In order to successfully develop lipid-based drug delivery systems (DDS) for oral administration of peptides and proteins, it is important to gain an understanding of the colloid structures formed by these DDS, the mode of peptide and protein incorporation as well as the mechanism by which intestinal absorption of peptides and proteins is promoted. The present paper reviews the literature on lipid-based DDS, employed for oral delivery of peptides and proteins and highlights the mechanisms by which the different lipid-based carriers are expected to overcome the two most important barriers (extensive enzymatic degradation and poor transmucosal permeability). This paper also gives a clear-cut idea about advantages and drawbacks of using different lipidic colloidal carriers ((micro)emulsions, solid lipid core particles and liposomes) for oral delivery of peptides and proteins. Lipid-based DDS are safe and suitable for oral delivery of peptides and proteins. Significant progress has been made in this area with several technologies on clinical trials. However, a better understanding of the mechanism of action in vivo is needed in order to improve the design and development of lipid-based DDS with the desired bioavailability and therapeutic profile.

Effect of MSH/ACTH peptides on fast axonal transport in intact and regenerating sciatic nerves

International Nuclear Information System (INIS)

Crescitelli, L.A.

1985-01-01

Fast axonal transport was examined in intact rats treated with ACTH 4-10 or ACTH 4-9 (ORG 2766), hypophysectomized rats, adrenalectomized rats, and in ACTH 4-10 treated rats with crushed regenerating sciatic nerves by injecting 3 H-leucine into the ventral horn region of the spinal cord. The distance traveled by the transported activity along the sciatic nerve and the rate of fast axonal transport were not significantly altered as a result of treatment with ACTH 4-10, ACTH 4-9 (ORG 2766), hypophysectomy, or adrenalectomy. Treatment with ACTH 4-9 (ORG 2766) at concentrations of 1 μg/Kg /day and 10 μg/Kg/day caused significant reductions (62% and 64% respectively) in the crest height of the fast axonal transport curve as compared to 0.9% saline treated control animals. No significant differences were found in comparing the distance, rate, slope, or crest height of ACTH 4-10 treated animals with crushed regenerating (7 or 14d) sciatic nerves to control animals. In the group of animals in days, the amount of radiolabeled activity was significantly increased in the ACTH 4-10 treated animals as compared to control animals. The results indicate that during regeneration the peptide acts to prolong the initially high levels of synthetic activity which occur in regenerating axons

Role of SbmA in the Uptake of Peptide Nucleic Acid (PNA)-Peptide Conjugates in E. coli

DEFF Research Database (Denmark)

Ghosal, Anubrata; Vitali, Ally; Stach, James E M

2013-01-01

Antisense PNA oligomers targeting essential genes (acpP or ftsZ) and conjugated to the delivery peptide L((KFF)(3)K) show complete growth inhibition of wild type E. coli strain (MG1655) with submicromolar MIC. In this study we show that resistant mutants generated against such PNA......-peptide conjugates had disruptions in the region of sbmA, a gene encoding an inner membrane peptide transporter. The wild type sensitivity to the PNA conjugates was re-established in the resistance mutants by complementation with sbmA. Furthermore, deletion of sbmA in E. coli AS19, a strain that is sensitive...

Intestinal lymphangiectasia: a forgotten cause of chronic diarrhea.

Science.gov (United States)

Rodríguez Leal, Gustavo

2006-01-01

Intestinal lymphangiectasia is a rare autosomal dominant disorder or acquired condition that leads to lymph obstruction, poor chyle transport and concomitant problems. We describe the cases of two women with chronic diarrhea in whom the common signs of lymphagiectasia-hypoalbuminemia, lymphopenia and distal edema- were found. One of them also had pleural effusion and chylous ascites. The diagnosis was performed by intestinal biopsy. We herein review the histopathologic, radiographic and endoscopic features of this disorder and case reports in Mexican population.

Usefulness of antibodies to deamidated gliadin peptides in celiac disease diagnosis and follow-up.

Science.gov (United States)

Volta, Umberto; Granito, Alessandro; Fiorini, Erica; Parisi, Claudia; Piscaglia, Maria; Pappas, Georgios; Muratori, Paolo; Bianchi, Francesco B

2008-06-01

The prevalence of the recently described deamidated gliadin peptide antibodies was compared with that of the routinely used antigliadin, antiendomysial, and tissue transglutaminase antibodies in the sera of 128 untreated celiac patients and 134 controls. Sensitivity and specificity for celiac disease were 83.6 and 90.3% for IgA and 84.4 and 98.5% for IgG antibodies to deamidated gliadin peptides. The new test displayed higher diagnostic accuracy than antigliadin antibodies and, although less sensitive than antiendomysial and tissue transglutaminase antibodies, showed significantly higher specificity than tissue transglutaminase antibodies (P < 0.001). Persistence of peptide antibodies after gluten withdrawal was an expression of low compliance with the diet and of the lack of improvement of the intestinal mucosa. The combined use of tissue transglutaminase and deamidated gliadin peptide antibodies seems to be a very useful tool for celiac disease diagnosis. Moreover, antibodies to deamidated gliadin peptides can be helpful in disease follow-up.

ttm-1 encodes CDF transporters that excrete zinc from intestinal cells of C. elegans and act in a parallel negative feedback circuit that promotes homeostasis.

Directory of Open Access Journals (Sweden)

Hyun Cheol Roh

2013-05-01

Full Text Available Zinc is an essential metal involved in a wide range of biological processes, and aberrant zinc metabolism is implicated in human diseases. The gastrointestinal tract of animals is a critical site of zinc metabolism that is responsible for dietary zinc uptake and distribution to the body. However, the role of the gastrointestinal tract in zinc excretion remains unclear. Zinc transporters are key regulators of zinc metabolism that mediate the movement of zinc ions across membranes. Here, we identified a comprehensive list of 14 predicted Cation Diffusion Facilitator (CDF family zinc transporters in Caenorhabditis elegans and demonstrated that zinc is excreted from intestinal cells by one of these CDF proteins, TTM-1B. The ttm-1 locus encodes two transcripts, ttm-1a and ttm-1b, that use different transcription start sites. ttm-1b expression was induced by high levels of zinc specifically in intestinal cells, whereas ttm-1a was not induced by zinc. TTM-1B was localized to the apical plasma membrane of intestinal cells, and analyses of loss-of-function mutant animals indicated that TTM-1B promotes zinc excretion into the intestinal lumen. Zinc excretion mediated by TTM-1B contributes to zinc detoxification. These observations indicate that ttm-1 is a component of a negative feedback circuit, since high levels of cytoplasmic zinc increase ttm-1b transcript levels and TTM-1B protein functions to reduce the level of cytoplasmic zinc. We showed that TTM-1 isoforms function in tandem with CDF-2, which is also induced by high levels of cytoplasmic zinc and reduces cytoplasmic zinc levels by sequestering zinc in lysosome-related organelles. These findings define a parallel negative feedback circuit that promotes zinc homeostasis and advance the understanding of the physiological roles of the gastrointestinal tract in zinc metabolism in animals.

Changes in Enteric Neurons of Small Intestine in a Rat Model of Irritable Bowel Syndrome with Diarrhea.

Science.gov (United States)

Li, Shan; Fei, Guijun; Fang, Xiucai; Yang, Xilin; Sun, Xiaohong; Qian, Jiaming; Wood, Jackie D; Ke, Meiyun

2016-04-30

Physical and/or emotional stresses are important factors in the exacerbation of symptoms in irritable bowel syndrome (IBS). Several lines of evidence support that a major impact of stress on the gastrointestinal tract occurs via the enteric nervous system. We aimed to evaluate histological changes in the submucosal plexus (SMP) and myenteric plexus (MP) of the distal ileum in concert with the intestinal motor function in a rat model of IBS with diarrhea. The rat model was induced by heterotypic chronic and acute stress (CAS). The intestinal transit was measured by administering powdered carbon by gastric gavage. Double immunohistochemical fluorescence staining with whole-mount preparations of SMP and MP of enteric nervous system was used to assess changes in expression of choline acetyltransferase, vasoactive intestinal peptide, or nitric oxide synthase in relation to the pan neuronal marker, anti-Hu. The intestinal transit ratio increased significantly from control values of 50.8% to 60.6% in the CAS group. The numbers of enteric ganglia and neurons in the SMP were increased in the CAS group. The proportions of choline acetyltransferase- and vasoactive intestinal peptide-immunoreactive neurons in the SMP were increased (82.1 ± 4.3% vs. 76.0 ± 5.0%, P = 0.021; 40.5 ± 5.9% vs 28.9 ± 3.7%, P = 0.001), while nitric oxide synthase-immunoreactive neurons in the MP were decreased compared with controls (23.3 ± 4.5% vs 32.4 ± 4.5%, P = 0.002). These morphological changes in enteric neurons to CAS might contribute to the dysfunction in motility and secretion in IBS with diarrhea.

Axonal transport and secretion of fibrillar forms of α-synuclein, Aβ42 peptide and HTTExon 1.

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Brahic, Michel; Bousset, Luc; Bieri, Gregor; Melki, Ronald; Gitler, Aaron D

2016-04-01

Accruing evidence suggests that prion-like behavior of fibrillar forms of α-synuclein, β-amyloid peptide and mutant huntingtin are responsible for the spread of the lesions that characterize Parkinson disease, Alzheimer disease and Huntington disease, respectively. It is unknown whether these distinct protein assemblies are transported within and between neurons by similar or distinct mechanisms. It is also unclear if neuronal death or injury is required for neuron-to-neuron transfer. To address these questions, we used mouse primary cortical neurons grown in microfluidic devices to measure the amounts of α-synuclein, Aβ42 and HTTExon1 fibrils transported by axons in both directions (anterograde and retrograde), as well as to examine the mechanism of their release from axons after anterograde transport. We observed that the three fibrils were transported in both anterograde and retrograde directions but with strikingly different efficiencies. The amount of Aβ42 fibrils transported was ten times higher than that of the other two fibrils. HTTExon1 was efficiently transported in the retrograde direction but only marginally in the anterograde direction. Finally, using neurons from two distinct mutant mouse strains whose axons are highly resistant to neurodegeneration (Wld(S) and Sarm1(-/-)), we found that the three different fibrils were secreted by axons after anterograde transport, in the absence of axonal lysis, indicating that trans-neuronal spread can occur in intact healthy neurons. In summary, fibrils of α-synuclein, Aβ42 and HTTExon1 are all transported in axons but in directions and amounts that are specific of each fibril. After anterograde transport, the three fibrils were secreted in the medium in the absence of axon lysis. Continuous secretion could play an important role in the spread of pathology between neurons but may be amenable to pharmacological intervention.

Glucagon-like peptide-1 analogues: An overview

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Vishal Gupta

2013-01-01

Full Text Available Abnormalities of the incretin axis have been implicated in the pathogenesis of type 2 diabetes mellitus. Glucagon-like peptide-1 (GLP-1 and gastroinhibitory intestinal peptide constitutes >90% of all the incretin function. Augmentation of GLP-1 results in improvement of beta cell health in a glucose-dependant manner (post-prandial hyperglycemia and suppression of glucagon (fasting hyperglycemia, amongst other beneficial pleiotropic effects. Native GLP-1 has a very short plasma half-life and novel methods have been developed to augment its half life, such that its anti-hyperglycemic effects can be exploited. They can be broadly classified as exendin-based therapies (exenatide, exenatide once weekly, DPP-4-resistant analogues (lixisenatide, albiglutide, and analogues of human GLP-1 (liraglutide, taspoglutide. Currently, commercially available analogues are exenatide, exenatide once weekly, and liraglutide. This review aims to provide an overview of most GLP-1 analogues.

The preferred substrates for transglutaminase 2 in a complex wheat gluten digest are Peptide fragments harboring celiac disease T-cell epitopes.

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Siri Dørum

Full Text Available BACKGROUND: Celiac disease is a T-cell mediated chronic inflammatory disorder of the gut that is induced by dietary exposure to gluten proteins. CD4+ T cells of the intestinal lesion recognize gluten peptides in the context of HLA-DQ2.5 or HLA-DQ8 and the gluten derived peptides become better T-cell antigens after deamidation catalyzed by the enzyme transglutaminase 2 (TG2. In this study we aimed to identify the preferred peptide substrates of TG2 in a heterogeneous proteolytic digest of whole wheat gluten. METHODS: A method was established to enrich for preferred TG2 substrates in a complex gluten peptide mixture by tagging with 5-biotinamido-pentylamine. Tagged peptides were isolated and then identified by nano-liquid chromatography online-coupled to tandem mass spectrometry, database searching and final manual data validation. RESULTS: We identified 31 different peptides as preferred substrates of TG2. Strikingly, the majority of these peptides were harboring known gluten T-cell epitopes. Five TG2 peptide substrates that were predicted to bind to HLA-DQ2.5 did not contain previously characterized sequences of T-cell epitopes. Two of these peptides elicited T-cell responses when tested for recognition by intestinal T-cell lines of celiac disease patients, and thus they contain novel candidate T-cell epitopes. We also found that the intact 9mer core sequences of the respective epitopes were not present in all peptide substrates. Interestingly, those epitopes that were represented by intact forms were frequently recognized by T cells in celiac disease patients, whereas those that were present in truncated versions were infrequently recognized. CONCLUSION: TG2 as well as gastrointestinal proteolysis play important roles in the selection of gluten T-cell epitopes in celiac disease.