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At least 19 recordsLinked to original sources
PubMed1987

Rise of prostanoids in rat small intestinal mucosa following intestinal protein hypersensitivity.

The purpose of the present study was to establish whether there is an elevated prostaglandin concentration in the intestinal mucosa in rats suffering from an immediate type hypersensitivity reaction. Rats of the Hooded-Lister strain were sensitized and challenged with ovalbumin. Control rats were given adjuvant only. Prostanoid content of scraped mucosa was determined by radioimmunoassay. It was found that the prostaglandin E2 content in the sensitized intestine was significantly elevated as compared to the controls. There was no significant rise of 6-keto prostaglandin F alpha or thromboxane E2 in the sensitized rats. These results show that prostaglandin B2 participates in intestinal immediate type responses and may explain some of the clinical manifestations of food protein allergy.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Purification and characterization of two aminopeptidases from guinea-pig small-intestinal mucosa. Cavian intestinal tripeptide hydrolases.

Two electrophoretically distinct cytosolic peptide hydrolases from guinea-pig small-intestinal mucosa have been highly purified by a six-step procedure comprising extraction from mucosal homogenate, ammonium sulphate fractionation, DEAE-cellulose chromatography, chromatofocusing, calcium phosphate chromatography and Sephadex G-100 gel filtration. They have similar apparent molecular masses as determined by gel filtration (Mr = 68 000) or by sodium dodecyl sulphate gel electrophoresis (Mr = 72 000). Both are aminopeptidases with optimum activity at pH 7.6. They are strongly inhibited by p-hydroxymercuribenzoate, o-phenanthroline and bestatin. Although both hydrolyse some dipeptides they have a distinctive kinetic preference for tripeptides composed of aromatic or non-polar residues. Their affinities for some tripeptides are particularly high and also the hydrolysis of some substrates exhibits biphasic kinetics. These two aminotripeptidases are similar but they can be differentiated from each other and from a number of other aminopeptidases.

Aminopeptidases↗
PubMed1991

Modifications of the trophism of intestinal mucosa after intestinal and bilio-pancreatic diversion in the rat.

Morphofunctional alterations to the intestinal mucosa are influenced by three main factors: food, bilio-pancreatic secretions, intestinal hormones. In order to assess the importance of each one, histological and histochemical tests were performed on different segments of intestine taken from rats which were sacrificed one month after the following procedure: gastrojejunal anastomosis on a Roux loop (Model I); same procedure plus biliopancreatic bypass into the jejunum (Model II). When compared to the controls, Model I duodenum samples revealed hypertrophy of the entire wall with "bundles" of villi, while Model II samples showed a clear hypotrophy and reduction in the number of duodenal villi. To such modifications of the duodenum correspond longer, thinner villi in the other bowel segments, particularly in the jejunum and distal ileum. These results suggest that the predominant trophic effect derives from contact with biliopancreatic secretions at a proximal level. The modifications of the duodenal mucosa appear to regulate the trophism of the distal segments probably by the secretion of distant acting enterohormones.

Adaptation, Physiological↗
PubMed1980

Studies on the incorporation of sn-[1,3-14C]glycerol 3-phosphate into glycerolipids by intestinal mucosa.

Intestinal mucosal microsomes from several animal species (non-fasted) were used to study the formation of glycerolipids from sn-[1,3-14C]glycerol 3-phosphate and palmitoyl-CoA. Rates of glycerolipid biosynthesis were species dependent, since mouse and rat were quite low compared to hamster, guinea pig and man. Under the usual incubation conditions, guinea pig intestinal microsomes formed primarily phosphatidic acid (85-90%). However, when Mg2+ was added to incubations containing intestinal microsomes prepared in the presence of 5 mM EDTA, there was a marked increase in neutral lipid biosynthesis (5-10-fold). These results suggest that intestinal microsomes contain mg2+-dependent phosphatidate phosphohydrolase (EC 3.1.3.4) which is involved in glycerolipid biosynthesis. All divalent cations studied increased sn-glycerol-3-phosphate acyltransferase (EC 2.3.1.15) activity; however, Ca2+, Ba2+, Zn2+, Cd2+, Ni2+, and Mn2+ antagonized the Mg2+-dependent rise in neutral lipid formation. In all cellular preparations studied, the ratio of neutral lipid (diacylglycerol + triacylglycerol) to total lipid (phosphatic acid + neutral lipid) was low, suggesting that phosphatidate phosphohydrolase may be rate limiting in intestinal neutral glycerolipid biosynthesis.

Animals↗
PubMed1973

Vitamin D and adenosine triphosphatase dependent on divalent cations in rat intestinal mucosa.

Intestinal brush borders prepared from vitamin D-deficient rats demonstrate increased susceptibility in vitro to fragmentation by shear forces or to loss of microvillus enzymes on treatment with EDTA. These effects are relatively nonspecific and are also observed in normal rats starved for 48 h. They may underlie prior observations that purport to demonstrate a vitamin D-dependent increase in brush border Ca-dependent ATPase. In addition, however, vitamin D increases ATPase activity dependent on certain divalent cations, including Ca and Zn, in whole-particulate suspensions pelleted by high-speed centrifugation of mucosal homogenates. This action is independent of changes in other microvillus enzymes, i.e. disaccharidases, and tissue distribution and cation specificity studies support the hypothesis that the mucosal whole-particulate ATPase is related to transport of Ca, Zn, and possibly other divalent cations.

Adenosine Triphosphatases↗
PubMed2006

Gliadin, zonulin and gut permeability: Effects on celiac and non-celiac intestinal mucosa and intestinal cell lines.

OBJECTIVE: Little is known about the interaction of gliadin with intestinal epithelial cells and the mechanism(s) through which gliadin crosses the intestinal epithelial barrier. We investigated whether gliadin has any immediate effect on zonulin release and signaling. MATERIAL AND METHODS: Both ex vivo human small intestines and intestinal cell monolayers were exposed to gliadin, and zonulin release and changes in paracellular permeability were monitored in the presence and absence of zonulin antagonism. Zonulin binding, cytoskeletal rearrangement, and zonula occludens-1 (ZO-1) redistribution were evaluated by immunofluorescence microscopy. Tight junction occludin and ZO-1 gene expression was evaluated by real-time polymerase chain reaction (PCR). RESULTS: When exposed to gliadin, zonulin receptor-positive IEC6 and Caco2 cells released zonulin in the cell medium with subsequent zonulin binding to the cell surface, rearrangement of the cell cytoskeleton, loss of occludin-ZO1 protein-protein interaction, and increased monolayer permeability. Pretreatment with the zonulin antagonist FZI/0 blocked these changes without affecting zonulin release. When exposed to luminal gliadin, intestinal biopsies from celiac patients in remission expressed a sustained luminal zonulin release and increase in intestinal permeability that was blocked by FZI/0 pretreatment. Conversely, biopsies from non-celiac patients demonstrated a limited, transient zonulin release which was paralleled by an increase in intestinal permeability that never reached the level of permeability seen in celiac disease (CD) tissues. Chronic gliadin exposure caused down-regulation of both ZO-1 and occludin gene expression. CONCLUSIONS: Based on our results, we concluded that gliadin activates zonulin signaling irrespective of the genetic expression of autoimmunity, leading to increased intestinal permeability to macromolecules.

Animals↗
PubMed1992

[The effects of dachengqi decoction, shaogan decoction, emodin and sennoside on the histamine level of intestinal mucosa in intestinally obstructed rats].

The experimental intestinal obstruction model was made by partly ligating the ileum in rat. The histamine levels of obstruction groups (8.14 +/- 2.28 micrograms/g) were obviously lower than those of control groups (P < 0.01). After administration of Dachengqi decoction, Shaogan decoction, emodin and sennoside, the levels of histamine were significantly higher than those of obstruction groups, but there were no significant differences as compared with control groups.

Animals↗
PubMed1984

Intestinal lymphangiectasia in the Lundehund. Scanning electron microscopy of intestinal mucosa.

Intestinal lymphangiectasia of obscure etiology is frequent among Norwegian Lundehunds ("puffin-dog"). A study of three Lundehunds with typical symptoms, including wasting, diarrhea and ascites, revealed segmental distention of lymphatics resembling primary lymphangiectasia in man. Atrophy, fusion and balloon-like swelling of villi with occasional rupture of lacteals were seen. Subepithelial fluid accumulation caused bulging of the epithelium. Microvilli showed partial or complete atrophy. The protein loss in the Lundehund enteropathy may be due to rupture of lacteals, increased paracellular permeability, caused by enhanced hydrostatic tissue pressure, and decreased absorption through a malformed brush border.

Animals↗
PubMed1997

CD4+ T cell down-regulation in human intestinal mucosa: evidence for intestinal tolerance to luminal bacterial antigens.

T cells from the intestinal mucosal proliferate poorly in vitro, and the contribution of Ag-specific recognition to this hyporesponsiveness is unclear, since the Ag repertoire of intestinal mucosal T cells is unknown. In this study, T cell proliferation in response to Ag-prepulsed autologous peripheral blood-derived APC was examined. Whereas T cells from peripheral blood proliferated to inner membrane and cytoplasmic Escherichia coli proteins, T cells from intestinal mucosa responded only to purified component Ags of these proteins and not to their combination. This suggests that the lack of proliferation in response to these Ags presented as a mixture is not due to the absence of E. coli-specific T cells in the mucosa, but, rather, to down-regulation after T cell recognition. Down-regulation was assayed by measuring the inhibition of autologous peripheral blood T cell proliferation in response to Ag-prepulsed APC. Coculture with leukocytes from intestinal mucosa and not from mesenteric lymph nodes, inhibited autologous peripheral blood T cell proliferation in response to E. coli proteins, but not to tetanus toxoid, PHA, or IL-2. Inhibition was independent of cell contact, provided APC were available to the mucosal cell population, and was reversible by neutralization of IL-10 or TGF-beta with mAb or depletion of mucosal CD4+ T cells. Taken together, the data suggest that mucosal T cell unresponsiveness to luminal Ags is mediated by production of inhibitory cytokines after specific Ag recognition by CD4+ T cells.

Aged↗
PubMed1996

Coenzyme A-independent monoacylglycerol acyltransferase from rat intestinal mucosa.

Rat intestinal mucosa contains high diacylglycerol-synthesizing activity (monoacylglycerol acyltransferase (MGAT) activity) due to monoacylglycerol and fatty acid, independently of coenzyme A and ATP. MGAT activity was purified from rat intestinal mucosa by successive chromatography separations on DEAE-cellulose, CM- Sephadex, and anti-IgG-Sepharose against rat pancreatic lipase. The enzyme was electrophoretically homogeneous, and its molecular weight was 49,000, which is identical with that of rat pancreatic lipase. Immunoblotting analysis with antibody against rat pancreatic lipase showed one immunoreactive protein with an estimated molecular weight of 49,000. The activity of the purified enzyme was completely inhibited by addition of the antibody. Using immunocytochemical techniques, it was found that immunoreactive protein against rat pancreatic lipase was uniformly distributed within the absorptive cells of the intestine but was absent from the microvillar membrane. The MGAT activity of intestinal mucosal homogenate was inhibited by about 65% by addition of antibody against rat pancreatic lipase. Trioleoylglycerol- and dioleoylglycerol-hydrolyzing activities of the purified enzyme and pancreatic lipase were inhibited by addition of intestinal mucosa extract. These results suggest that pancreatic lipase is present in intestinal absorptive cells and that it may contribute to resynthesis of diacylglycerol from monoacylglycerol and fatty acids in these cells.

Acyltransferases↗
PubMed2005

Immune responses that adapt the intestinal mucosa to commensal intestinal bacteria.

Animals contain an enormous load of non-pathogenic bacteria in the lower intestine, which exploit an environment with a stable temperature and abundant carbon sources. Our load of bacteria outnumbers our own cells. In order to survive with such a high number of organisms in very close proximity to host tissues the intestinal mucosa and its immune system is highly adapted. Mucosal immune responses are induced by small numbers of live commensal organisms penetrating the Peyer's patches and persisting in dendritic cells (DC). These DC can induce immunoglobulin A+ (IgA+) B cells, which recirculate through the lymph and bloodstream to populate the lamina propria and secrete protective IgA. Because DC loaded with commensal bacteria do not penetrate further than the mesenteric lymph nodes, immune induction to commensals is confined to the mucosa, allowing strong mucosal immune responses to be induced whilst the systemic immune system remains relatively ignorant of these organisms.

Adaptation, Physiological↗
PubMed1967

Enzymic hydrolysis of the carbon-fluorine bond of alpha-D-glucosyl fluoride by rat intestinal mucosa. Localization of intestinal maltase.

1. alpha-d-Glucosyl fluoride was hydrolysed by an extract of rat intestinal mucosa. The pH optimum was 6.6 and the K(m) 0.4mm at 20 degrees . Activity was assayed by release of either glucose or fluoride. 2. The alpha-d-glucosyl fluoride-hydrolase activity of the extract was associated with both mutarotase and alpha-d-glucosidase activities. 3. Tris (5mm) inhibited both the alpha-d-glucosidase and alpha-d-glucosyl fluoride-hydrolase activities by 55% but did not inhibit mutarotase. The K(i) of tris for both enzyme activities was 2mm. 4. The extract did not hydrolyse melibiose and lactose. Mutarotase used both alpha-d-glucose and beta-l-arabinose as substrates but the glucosyl fluoride-hydrolase activity did not extend to beta-l-arabinosyl fluoride. 5. The thermal stability of alpha-d-glucosidase and alpha-d-glucosyl fluoride hydrolase was identical. Mutarotase was more thermolabile. 6. A preparation of the brush border of intestinal epithelial cells contained both alpha-d-glucosyl fluoride-hydrolase and alpha-d-glucosidase activities. In each precipitate and washing the ratio of the two activities was the same. All the mutarotase activity was in the first supernatant. 7. Agidex, a fungal amyloglucosidase, cleaved glucosyl fluoride in addition to maltose. Tris inhibited both activities and in each case the K(i) was 3mm. 8. The probable identity of alpha-d-glucosyl fluoride hydrolase with alpha-d-glucosidase is discussed and a possible mechanism for the reaction suggested. 9. Incubation of intestinal slices with alpha-d-glucosyl fluoride led to complete hydrolysis in 30min. The glucose rapidly entered the cell and was metabolized, leaving the fluoride in the incubation medium. This constitutes a further proof that the intestinal alpha-d-glucosidase, although on the brush border, is located outside the site of active transport of sugars.

Animals↗
PubMed1987

The significance of colonic mucosa (intestinal metaplasia) involving the urinary tract.

Although colonic type goblet cells are a relatively common component of reactive urothelial lesions and well-differentiated adenocarcinomas, complete replacement of areas of urothelium by benign appearing intestinal mucosa is a rare condition. All of the 11 documented cases occurred in association with abnormalities leading to chronic irritation and/or infection. In the three cases where the reported period of observation exceeded 2 years, all patients developed carcinoma. Despite its innocuous histology, widespread intestinal metaplasia apparently identifies a disturbed urothelium at high risk for cancer.

Carcinoma↗