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At least 1,009 records · Page 56Linked to original sources
PubMed1978

Effects of vasoactive intestinal polypeptide on intestinal absorption and blood flow.

1. Intestinal absorption and blood flow in anaesthetized dogs was determined after I.V. infusion of vasoactive intestinal polypeptide (VIP) (1.75-175 ng/min) to determine the contribution of the cardiovascular changes to transport. 2. 22Na and 3H2O were utilized to determine the unidirectional fluxes of Na and H2O from saline perfused through the ileal lumen and the clearances of 3H2O were used to determine total and absorptive site blood flow. 3. Net Na and H2O absorption were reversed to secretion by VIP at 175 ng/min due to a significant decrease in unidirectional absorptive fluxes and smaller increases in secretory fluxes. 4. Arterial pressure and absorptive site blood flow were reduced in proportion to the changes in Na and H2O fluxes. 5. Total and absorptive site blood flow decreased and the blood flow resistances increased. 6. Prior treatment with guanethidine to suppress sympathetic effects did not greatly affect the responses to VIP. Prior treatment with atropine to suppress cholinergic effects inhibited most of the effects of VIP. 7. Absorptive site blood flow was linearly related to absorptive fluxes of Na and H2O but with different slopes for results from atropinized dogs as compared to those from dogs given VIP alone or VIP plus guanethidine. 8. It was concluded that VIP reduces gut absorption through a generalized cardiovascular effect and also through a mechanism which depends on the release of ACh by the gut.

Animals↗
PubMed1987

Adhesion of enteropathogenic Escherichia coli to human intestinal enterocytes and cultured human intestinal mucosa.

The adhesion of classic enteropathogenic Escherichia coli (EPEC) strains of human origin to isolated human small intestinal enterocytes and cultured small intestinal mucosa was investigated. An adhesion assay with isolated human enterocytes prepared from duodenal biopsy samples was developed and tested with EPEC strains known to cause diarrhea in healthy adult volunteers. In the assay a mean of 53 and 55% of enterocytes had brush border-adherent E. coli E2348 (O127;H6) and E851 (O142:H6), respectively, whereas the value for a nonpathogenic control strain and a plasmid-cured derivative of strain E2348 was 0%. A collection of 17 EPEC strains was also tested for the ability to colonize cultured human duodenal mucosa. Extensive colonization occurred with 13 strains, including serogroups O55, O86, O111, O114, O119, O127, O128, and O142; and in each case electron microscopic examination of colonized mucosa revealed the characteristic histopathological lesion reported by others in natural and experimental EPEC infections. EPEC strains were seen to adhere intimately to the enterocyte surface, causing localized destruction of microvilli. The plasmid-cured derivative of strain E2348, which colonized cultured mucosa much less efficiently than the parent strain, nevertheless produced an identical lesion, indicating that plasmid-encoded factors are not essential for adhesion and the brush border-damaging property of EPEC.

Bacterial Adhesion↗
PubMed2004

Epiregulin is not essential for development of intestinal tumors but is required for protection from intestinal damage.

Epiregulin, an epidermal growth factor family member, acts as a local signal mediator and shows dual biological activity, stimulating the proliferation of fibroblasts, hepatocytes, smooth muscle cells, and keratinocytes while inhibiting the growth of several tumor-derived epithelial cell lines. The epiregulin gene (Ereg) is located on mouse chromosome 5 adjacent to three other epidermal growth factor family members, epigen, amphiregulin, and betacellulin. Gene targeting was used to insert a lacZ reporter into the mouse Ereg locus and to ablate its function. Although epiregulin is broadly expressed and regulated both spatially and temporally, Ereg null mice show no overt developmental defects, reproductive abnormalities, or altered liver regeneration. Additionally, in contrast to previous hypotheses, Ereg deficiency does not alter intestinal cancer susceptibility, as assayed in the ApcMin model, despite showing robust expression in developing tumors. However, Ereg null mice are highly susceptible to cancer-predisposing intestinal damage caused by oral administration of dextran sulfate sodium.

Animals↗
PubMed1985

Intestinal function and intestinal blood supply: a 20 year surgical study.

The experience of The Middlesex Hospital in the investigation and management of chronic intestinal arterial occlusion (IAO) over a 20 year period is presented. Of some 100 patients referred only 28 were found to have IAO and these were critically evaluated in terms of insorptive and exsorptive function. No relation was found between intestinal performance and the degree of potential ischaemia suggested by angiography. Twenty two patients underwent reconstruction of the coeliac axis and mesenteric arteries, with three perioperative deaths. The remainder were followed for periods ranging between six months and 10 years. Of these, 15 are asymptomatic, one is unchanged, and one is subjectively worse. The role of elective surgery in relation to the visceral arteries is critically discussed in the light of these results, and in the perspective of the world experience.

Adult↗
PubMed1984

Regulation of intestinal goblet cell secretion. III. Isolated intestinal epithelium.

Cholinergic secretagogues evoke mucus secretion from goblet cells in the crypts of small and large intestinal mucosa in vivo and in organ culture. It was not known whether this response reflected a direct action on epithelial cell receptors or an indirect effect involving intermediate neurons of the enteric nervous system. To resolve this, carbachol was applied to isolated intestinal epithelium maintained in vitro. Intact sheets of epithelium, measuring 10-200 mm2, were isolated from the ileum and colon of adult rats following short intravascular perfusion with 30 mM EDTA. The isolated epithelia lacked a basal lamina and cytoplasmic blebs formed on the basal cell surfaces, but cell ultrastructure was normal and intercellular junctions were intact. Autoradiography revealed that both goblet and columnar cells continued to incorporate [3H]glucosamine into nascent secretory macromolecules for at least 45 min after isolation. When exposed to 20 microM carbachol for 5 min, crypt goblet cells discharged their stored mucin granules by compound exocytosis, whereas goblet cells in portions of the epithelium derived from villi or mucosal surfaces were unresponsive. We conclude that cholinergic secretagogues act directly on crypt epithelial cells to elicit mucus secretion.

Animals↗
PubMed1994

Role of nitric oxide-related inhibition in intestinal function: relation to vasoactive intestinal polypeptide.

This study examined the role of nitric oxide (NO) in tonic inhibition of motor activity in isolated, perfused canine ileal segments. Brief addition of N omega-nitro-L-arginine methyl ester (L-NAME) to the perfusate caused, after a delay, a concentration-dependent persistent increase in tonic and phasic activity of circular muscle. This increased motor activity was prevented or reversed by addition of L- but not D-arginine to the perfusate. Removal of Ca2+ or addition of 10(-7) M omega-conotoxin (GVIA) to the perfusate markedly reduced this response. The motor activity induced by L-NAME was accompanied by loss of distal inhibition and enhanced excitation to low-frequency field stimulation. L-NAME infusion significantly reduced tonic vasoactive intestinal polypeptide (VIP) output, sodium nitroprusside increased VIP output, but L-arginine infusion did not restore VIP output. Atropine (10(-7) M) and/or hexamethonium (10(-4) M) reduced the motor response to L-NAME by 75%. Atropine reduced and hexamethonium nearly abolished VIP output. We conclude that there is tonic Ca(2+)-dependent NO output from perfused intestinal segments dependent on nerves with N-Ca channels, that NO acts to inhibit muscle directly and by inhibiting release of excitatory mediators, and that this output is the primary inhibitory determinant of contractile activity.

Acetylcholine↗
PubMed1997

Intestinal anaphylaxis induces Fos immunoreactivity in myenteric plexus of rat small intestine.

Fos immunohistochemistry was used to identify myenteric neurons activated as a consequence of intestinal anaphylaxis in Hooded-Lister rats sensitized to egg albumin (EA 10 micrograms ip). After incubation in test solutions, or after in vivo challenge, jejunal tissues were processed for immunohistochemistry with an anti-Fos antibody (1:500, TF161). The neuronal identity of the Fos-labeled nuclei was confirmed by double labeling with neuron-specific enclose (1:1,000). In in vitro studies, exposure of control tissue to 50 mM K(+)-Krebs-EA (2 x 10(-5) M) solutions significantly increased Fos immunoreactivity in the myenteric plexus, whereas a basal level of Fos was seen in control tissue incubated in Krebs solution, sham-sensitized tissue exposed to bovine serum albumin (BSA, 2 x 10(-5) M), or EA and sensitized tissue exposed to BSA. Pretreatment of sensitized tissue with doxantrazole (10(-4) M) markedly reduced Fos immunoreactivity observed after EA exposure. In in vivo studies, there was negligible Fos immunoreactivity in the myenteric plexus of control, sham-sensitized, or sensitized rats challenged with saline. A low level of Fos was seen in neurons of sham-sensitized rats challenged with BSA or EA and in sensitized rats challenged with BSA. Significantly greater levels of Fos were observed in the myenteric plexus of sensitized animals challenged with EA, even after pretreatment with capsaicin (125 mg/kg). These results suggest a role for myenteric neurons in intestinal anaphylaxis. In sensitized rats, activation of myenteric neurons is dependent on antigen-induced mast cell activation and occurs independently of capsaicin-sensitive afferent nerves.

Anaphylaxis↗
PubMed1997

Vasoactive intestinal peptide modulates T lymphocyte migration in Peyer's patches of rat small intestine.

Although vasoactive intestinal peptide (VIP) has been postulated to function in modulation of T cell trafficking, the exact mechanism has not been elucidated in vivo. In the present study, the effects of VIP on T lymphocyte migration were examined in rat Peyer's patches. T lymphocytes collected from intestinal lymph of rats were labeled with carboxyfluorescein diacetate succinimidyl ester and injected into the jugular vein. Peyer's patches of the recipient rats were observed with intravital fluorescence microscopy. In vivo intra-arterial infusion of or in vitro incubation with VIP did not affect the initial lymphocyte interaction with postcapillary venules of Peyer's patches. However, these treatments with VIP significantly inhibited transendothelial migration and also significantly blocked the interstitial migration of T cells and inhibited their subsequent appearance in the interfollicular lymphatics. Treatment with adenosine 3',5'-cyclic monophosphate (cAMP)-inducing agents resulted in similar inhibitory effect on T lymphocyte migration in Peyer's patches. In conclusion, VIP has significant inhibitory effects on T lymphocyte migration in Peyer's patches, possibly mediated by elevation of the intracellular cAMP concentrations.

Animals↗
PubMed1978

Hypersensitivity reactions in the small intestine. IV. Influence of allograft rejection on small intestinal mucosal architecture: a scanning and transmission electron microscope study.

The effect of a local delayed hypersensitivity reaction (allograft rejection) on small intestinal architecture has been examined by using scanning electron microscopy of the mucosal surface. In isografts, regarded as a morphological basis for normality of the system, the villi appeared normal and finger like. In allografts the appearances ranged from fairly normal areas to others with stunted and ridged villi, and flat areas in which crypt mouths opened on to the flat mucosal surface. The fine structure of epithelial cells was studied further by transmission electron microscopy. There was an apparent reduction in the size of the microvillous border in allografts but no other consistent abnormality. The similarities between this model of allograft rejection, and untreated coeliac disease in man, are highlighted and contrasted with the effects of acute radiation injury on the intestine.

Animals↗
PubMed1986

Intestinal calcium absorption in patients after jejuno-ileal bypass or small intestinal resection and the effect of vitamin D.

A forearm counter and double-isotope technique were used to measure intestinal calcium absorption in 21 patients after jejuno-ileal bypass for obesity or small intestinal resection. In all but 2 patients calcium absorption was below the normal range for 10 male controls. 3 weeks treatment with 1-alpha-hydroxyvitamin D, 1 microgram b.d., or 1,25-dihydroxyvitamin D, 1 microgram b.d., was associated with significant increases in absorption whereas 3 weeks treatment with 24,25-dihydroxyvitamin D had no effect. This study demonstrates that oral 1,25-dihydroxyvitamin D or 1-alpha-hydroxyvitamin D are effective in increasing calcium absorption.

24,25-Dihydroxyvitamin D 3↗
PubMed1977

Disaccharidase and lysosomal enzyme activities in amniotic fluid, intestinal mucosa and meconium. Correlation between morphology and disaccharidase activities in human fetal small intestine.

Brush border membrane bound disaccharidases (sucrase and maltase) and lysosomal enzyme (alpha-glucosidase, beta-D-fucosidase and N-acetyl-beta-glucosaminidase) activities awere studied in amniotic fluid (AF). The above enzymes except N-acetyl-beta-glucosaminidase showed a decrease in activity with gestational age beginning at about the 19th week. The activities of sucrase and maltase correlate with the morphological maturation of fetal intestinal mucosa. The distribution of disaccharidases and lysosomal alpha-glucosidase in AF and intestinal mucosa showed different patterns suggesting that these enzymes originate in diverse fetal tissues.

Acetylglucosaminidase↗
PubMed1978

Intestinal secretion induced by vasoactive intestinal polypeptide. A comparison with cholera toxin in the canine jejunum in vivo.

The effect of vasoactive intestinal polypeptide (VIP) on intestinal water and electrolyte transport and transmucosal potential difference was investigated in the dog jejunum in vivo and compared to secretion induced by cholera toxin. Isolated jejunal loops were perfused with a plasma-like electrolyte solution. VIP (0.08 mug/kg per min) was administered directly into the superior mesenteric artery by continuous infusion over 1 h. From a dye dilution method, it was estimated that a mean plasma VIP concentration of 12,460 pg/ml reached the loops. VIP caused secretion of water and electrolytes; for example, chloride: control, 8 mueq/cm per h absorption; VIP, 92 mueq/cm per h secretion. A marked increase in transmucosal potential difference (control, -1.0 mV; VIP, -5.9 mV, lumen negative) occurred within 1 min after starting VIP infusion. Analysis of unidirectional fluxes showed increased plasma-to-lumen flux of sodium and chloride and decreased lumen-to-plasma flux of sodium. Chloride and bicarbonate were actively secreted against an electrochemical gradient. Although sodium secretion occurred down an electrochemical gradient, flux ratio analysis suggested a component of active sodium secretion. VIP caused a slight increase in protein output into the loops; light microscopy revealed capillary dilatation and closed intercellular spaces. The effect of VIP was readily reversible. Except for the delayed onset of secretion, the effect of cholera toxin was qualitatively similar to VIP; however, capillary dilatation and increased protein output were not noted with cholera toxin.

Animals↗
PubMed2000

Chronic intestinal pseudo-obstruction in systemic lupus erythematosus due to intestinal smooth muscle myopathy.

We report the case of a woman with systemic lupus erythematosus initially manifesting with fever, rash and arthritis, and two years later with Class IV lupus nephritis. Following treatment with cyclophosphamide she developed symptoms and signs of chronic intestinal pseudo-obstruction (CIPO) that was initially thought to be due to a neutropenic enterocolitis. However, persistence of symptoms resulted in segmental resection of the ileum which showed widespread myocyte necrosis and active inflammation within the muscularis propria. A subsequent, more extensive ileocolic resection showed severe diffuse atrophy and fibrosis of the muscularis propria throughout the resected bowel. The absence of mesenteric vasculitis and the clinical response of the CIPO to the immunosupressive regimen of prednisolone and cyclosporin A suggest that the bowel muscle coat changes reflect an intestinal myopathy secondary to systemic lupus erythematosus, and may have an auto-immune etiology.

Adult↗
PubMed1997

Changes in messenger RNA of pancreatic enzymes and intestinal cholecystokinin after a 7-day bile-pancreatic juice diversion from the proximal small intestine in rats.

We have previously demonstrated the bile-pancreatic juice (BPJ)-independent stimulation of pancreatic enzyme secretion in chronic BPJ-diverted rats. Pancreatic and intestinal adaptation to 7-day BPJ diversion was next examined. Pancreatic enzyme mRNA and cholecystokinin mRNA in the jejunal mucosa were measured in rats with BPJ diverted into the ileum (PBD rats) in comparison with the figures for rats with BPJ returned to the duodenum (normal rats) or laparotomized (Intact) rats under well-nourished conditions. Amylase mRNA in the pancreas was lower and trypsinogen plus chymotrypsinogen mRNA was higher in the PBD rats than in the intact rats. The change in pancreatic mRNA was similar to that in the specific activities of the enzymes after a chronic BPJ diversion. This finding suggests that these pancreatic enzymes were regulated by the mRNA level. The portal concentration of cholecystokinin in the postabsorptive period (exogenously non-stimulated status) was 4-fold higher in the PBD group than in the normal and intact groups. Cholecystokinin mRNA in the jejunal mucosa of PBD rats was somewhat higher than that of intact rats. These results suggest that intestinal cholecystokinin was predominantly increased at the translational or later stage by chronic BPJ diversion.

Absorption↗
PubMed1988

Characterization of peptidylglycine alpha-amidating activities in rat pituitary, brain and small intestine using glycine-extended C-terminal analogues of vasoactive intestinal polypeptide as substrate.

Peptidylglycine alpha-amidating activities from rat pituitary, brain and small intestine were compared, utilizing C-terminal analogues of vasoactive intestinal polypeptide (VIP), D-Tyr-Leu-Asn-Gly and D-Tyr-Asn-Gly, and C-terminal analogue of alpha-MSH, D-Tyr-Val-Gly. The three tissues had enzymic activities capable of converting the glycine-extended peptides to the corresponding alpha-amidated ones. In other words, all of three peptides could serve as substrates for the enzymes from both neural and gastrointestinal tissues. The activities were stimulated in the presence of copper and ascorbate; the optimal concentration of each cofactor was roughly equal for the three enzymes; similar pH profiles (a neutral pH optimum at 6.5-7 and another one at 8-8.5) were also observed. Desamide VIP-Gly was proved to be a potent inhibitor of the alpha-amidating activities from the tissues, but VIP was not, indicating that the alpha-amidating enzymes from these tissues in common have a recognition site for the C-terminal glycine of the glycine-extended precursor regardless of the length and nature of the sequence. No fundamental differences were observed between the catalytic properties of the alpha-amidating activities from these three tissues, raising the possibility that similar enzymes, which may or may not be a single species, are functioning in tissues that produce alpha-amidated polypeptides in vivo.

Amino Acid Sequence↗
PubMed2006

Identification by microarray of a common pattern of gene expression in intact intestine and cultured intestinal cells exposed to virulent Aeromonas hydrophila isolates.

The genus Aeromonas comprises known virulent and avirulent isolates and has been implicated in waterborne disease. A common infection model of human gastroenteritis associated with A. hydrophila uses neonatal mice. The goal of this research was to evaluate whether a murine small intestinal cell line could provide comparable results to the gene expression changes in the neonatal mouse model. Changes in mRNA expression in host cell cultures and intestinal tissues were measured after exposure to virulent Aeromonas hydrophila strains. A. hydrophila caused the up-regulation of more than 200 genes in neonates and over 50 genes in cell culture. Twenty-six genes were found to be in common between the two models, of which the majority are associated with the innate immune response.

Aeromonas hydrophila↗
PubMed2002

Intestinal urea metabolism: could the bacteria involved in nitrogen cycle lead to reutilization of intestinal urea nitrogen in uremic rabbits?

We aimed to evaluate the effect of bacteria involved in the nitrogen cycle on the reutilization of intestinal urea nitrogen in uremic rabbits. New Zealand white rabbits were made uremic via bilateral nephrectomy. Study and control rabbits were given live and heat-inactivated bacteria through their jejunostomies. After they were injected with 99mTc biurea intravenously, serial serum and stool levels of labeled nitrogen were assessed by instant thin-layer chromatography, and the change in the labeled-nitrogen level was determined. The serum labeled-nitrogen level increased significantly in the study group (r=0.990); however, this level decreased in the control group (r=0.662). Furthermore, the labeled-nitrogen level in the stool samples increased throughout the study in the control rabbits, but it decreased after the 6th hour in the study group. In conclusion, the results of this study suggest that when the bacterial flora of the intestinal system is changed to include bacteria involved in the nitrogen cycle in uremic rabbits, the intraintestinal and systemic nitrogen metabolisms could both be altered in favor of positive nitrogen balance.

Animals↗