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PubMed2000

Effects of several endothelin receptor antagonists on gastrointestinal transit of guinea pigs.

This study was undertaken to investigate the effects of endothelin(A) receptor antagonist (ET(A)-RA) BQ485; ET(B)-RA BQ788, and nonselective ET(A/B)-RA Bosentan on the gastrointestinal transit of guinea pigs. We further analyzed the distribution of ET-R subtypes on smooth muscle cells (SMC) of the gastrointestinal tract to investigate their direct involvement on SMC in gastrointestinal tract transit. A guinea pig model was used to measure intestinal transit. The effects of Bosentan (100 mg/kg, per os), BQ485 (1 mg/kg, intraperitoneally) and BQ788 (1 mg/kg, intraperitoneally) on transit in stomach, small intestine, and colon were evaluated. We separated SMC from stomach, small intestine, cecum, and colon by collagenase and analyzed the distribution of ET-R subtypes in each part by binding assay. Gastric transit and colon transit were significantly inhibited by BQ485, BQ788, and Bosentan. Small intestinal transit was not affected by any of these agents. ET(A)-R and ET(B)-R were widely distributed on SMC of stomach, small intestine, cecum, and colon. The ratio of ET(A)-R to ET(B)-R was 1:3 in stomach, small intestine, and cecum, but was 1:10 in colon. The ratio of the total number of ET-R on SMC of stomach, small intestine, cecum, and colon was 1:3:9:1. These results indicate that both ET(A)-R and ET(B)-R are strongly involved in the transit in the stomach and colon. However, the discrepancy between the effects of the various ET-R antagonists on gastrointestinal transit and the distribution of ET-R on SMC of the gastrointestinal tract suggests that ET-R on SMC of the gastrointestinal tract is not directly involved in gastrointestinal transit.

Animals↗
PubMed2001

Salmonella enterica serovar-host specificity does not correlate with the magnitude of intestinal invasion in sheep.

The colonization of intestinal and systemic tissues by Salmonella enterica serovars with different host specificities was determined 7 days after inoculation of 1 to 2-month-old lambs. Following oral inoculation, S. enterica serovars Abortusovis, Dublin, and Gallinarum were recovered in comparable numbers from the intestinal mucosa, but serovar Gallinarum was recovered in lower numbers than the other serovars from systemic sites. The pattern of bacterial recovery from systemic sites following intravenous inoculation was similar. The magnitude of intestinal invasion was evaluated in ovine ligated ileal loops in vivo. Serovars Dublin and Gallinarum and the broad-host-range Salmonella serovar Typhimurium were recovered in comparable numbers from ileal mucosa 3 h after loop inoculation, whereas the recovery of serovar Abortusovis was approximately 10-fold lower. Microscopic analysis of intestinal mucosae infected with serovars Typhimurium and Dublin showed dramatic morphological changes and infiltration of inflammatory cells, whereas mucosae infected with serovars Abortusovis and Gallinarum were indistinguishable from uninfected mucosae. Together these data suggest that Salmonella serovar specificity in sheep correlates with bacterial persistence at systemic sites. Intestinal invasion and avoidance of the host's intestinal inflammatory response may contribute to but do not determine the specificity of serovar Abortosovis for sheep. Intestinal invasion by serovar Abortusovis was significantly reduced after mutation of invH but was not reduced following curing of the virulence plasmid, suggesting that the Salmonella pathogenicity island 1 influences but the virulence plasmid genes do not influence the ability of serovar Abortusovis to invade the intestinal mucosa in sheep.

Animals↗
PubMed1986

Evidence against VIP as the inhibitory transmitter in non-adrenergic, non-cholinergic nerves supplying the longitudinal muscle of the mouse colon.

Vasoactive intestinal peptide (VIP) had two types of effects on the longitudinal muscle of the mouse distal colon. At low concentrations (10(-8) M) VIP induced a contraction which seemed to be related to the production of prostaglandins as it was abolished after preincubation with indomethacin (10(-6) M). At higher concentrations (3 X 10(-8) and 10(-7) M) VIP induced relaxations which developed slowly and were related to stimulation of the adenylate cyclase activity of the smooth muscle cells. There is no evidence that VIP is the non-adrenergic, non-cholinergic transmitter released by electrical stimulation in this preparation and responsible for rapid relaxation of the smooth muscle.

Adenylyl Cyclases↗
PubMed2000

Bcl-w is an important determinant of damage-induced apoptosis in epithelia of small and large intestine.

The potential role of the bcl-2 relative bcl-w as a physiological regulator of apoptosis in intestinal epithelia has been investigated. Immunoblots for bcl-w with new monoclonal antibodies revealed that it was expressed in the small intestine and colon, among other murine tissues, as well as in six human tumour cell lines of epithelial origin, including two colon carcinoma lines. To assess whether bcl-w regulates either spontaneous or damage-induced apoptosis in the small intestine or colon, apoptosis in intestinal crypts of bcl-w -/- and wild-type mice was quantified microscopically on a cell positional basis. Spontaneous apoptosis within crypt epithelia was not significantly increased by loss of bcl-w, in either the small intestine or midcolon. However, after treatment with the cytotoxic drug 5-fluorouracil or with gamma-radiation, the bcl-w-null animals exhibited substantially more apoptosis than their wild-type counterparts in both tissues. The greatest enhancement of apoptosis attributable to the absence of bcl-w (up to sixfold) occurred in the small intestine. Hence, bcl-w is an important determinant of damage-induced apoptosis in intestinal epithelia, and unlike bcl-2, which regulates only colonic apoptosis, plays a major role in small intestinal epithelium.

Animals↗
PubMed2005

Development and resolution of experimental colitis in mice with targeted deletion of dipeptidyl peptidase IV.

Glucagon-like peptide-2 (GLP-2) is a potent intestinotrophic growth factor that enhances repair of damaged intestinal tissue. However, its bioactivity is limited by dipeptidyl peptidase IV (DPIV)-mediated degradation. We hypothesized that DPIV(-/-) mice would display an increased resistance to, and an enhanced recovery from, dextran sulfate sodium (DSS)-induced colitis compared to DPIV(+/+) mice. DPIV(+/+) and DPIV(-/-) mice consumed 2% DSS for 6 days, followed by a 15 day recovery period. Mice were killed at days 0, 3, 6, 9, 14, and 21 (n = 6-8) and the small intestine and colon removed for histological assessment of villus height, crypt depth, and crypt area. The epithelial cell proliferative labeling index was determined by proliferating cell nuclear antigen (PCNA) immunostaining. Small intestine, colon, and total body weight did not differ between DPIV(+/+) and DPIV(-/-) mice. Distal colon crypt depth did not differ significantly between DPIV(+/+) and DPIV(-/-) mice during the development of DSS-colitis or during the recovery phase. Similarly no significant effects were apparent on distal colon crypt area or PCNA labeling index between DPIV(+/+) and DPIV(-/-) during the development of and recovery from DSS-colitis. However, DPIV(-/-) mice still possessed significant levels of plasma DPIV-like activity. We conclude that loss of DPIV activity does not increase resistance to experimental colitis and hypothesize that other DPIV family members may also be involved in the cleavage of GLP-2.

Animals↗
PubMed1999

APC-dependent changes in expression of genes influencing polyamine metabolism, and consequences for gastrointestinal carcinogenesis, in the Min mouse.

The colorectal mucosa of pre-symptomatic individuals with familial adenomatous polyposis (FAP) contains elevated levels of the proliferation-associated polyamines. The Min mouse, like humans with FAP, expresses an abnormal genotype for the APC tumor suppressor gene. In order to determine how APC mutation influences intestinal tissue polyamine content, we measured steady-state RNA levels of ornithine decarboxylase (ODC), the first enzyme in polyamine synthesis, antizyme (AZ), a protein which negatively regulates ODC, and the spermidine/spermine N(1)-acetyltransferase (SSAT), the first enzyme in polyamine catabolism. RNA content was increased 6- to 8-fold in both the small intestine and colon for ODC, decreased significantly in the small intestine but not the colon for AZ and was not statistically different in either intestinal tissue for SSAT in Min mice compared with normal littermates. Consistent with the changes in ODC and AZ gene expression, small intestinal, but not colonic, polyamine content was elevated in Min mice compared with normal littermates. Treatment of Min mice with the specific ODC inhibitor difluoromethylornithine (DFMO) suppressed small intestinal, but not colonic, polyamine content and tumor number. These data indicate that small intestinal tissue polyamine content is elevated in Min mice by a mechanism involving APC-dependent changes in ODC and AZ RNA. Further, ODC enzyme activity, which is influenced by both ODC and AZ RNA levels and inhibited by DFMO, is consequential for small intestinal tumorigenesis in this model. In the FAP population, DFMO may be of value in the chemoprevention of small intestinal adenocarcinoma that remains a risk following colectomy.

Acetyltransferases↗
PubMed1980

Intestinal metaplasia with colonic-type sulphomucins in the gastric mucosa; its association with gastric carcinoma.

The occurrence of intestinal metaplasia with colonic-type sulphomucins: (abbreviated: s-IM or s-positive IM) in the gastric mucosa was studied in 125 patients with gastric carcinoma (GCA), 62 patients with pernicious anemia (PA), 301 and 183 first-degree relatives of GCA and PA patients, 406 outpatients and in 358 controls matched from a large population sample. The sulphomucins (s-mucins) were demonstrated histochemically in endoscopic biopsy specimens by using high iron diamine and Alcian blue (pH 1) methods. The prevalence of s-IM, especially the strongly s-positive IM, was significantly higher in GCA patients than in other series or controls of the same age group. Further, s-IM was significantly more common in PA patients and its prevalence higher in GCA relatives and outpatients than in other series or controls. The occurrence of s-IM was also age-dependent and dependent on the extent of IM. It was suggested that the occurrence of s-IM can be used as a sign of lesions that are more closely associated with GCA than IM is in general.

Adult↗
PubMed2002

Nutritional advantages of probiotics and prebiotics.

The potential 'nutritional advantages' of probiotics and prebiotics consist of preventive, and sometimes curative, effects against certain diseases. The evidence supporting such advantages, which requires randomised controlled trials and consistency of results from study to study, is rapidly increasing. This article summarizes the effects against diseases of intestinal origin. There is a high level of evidence for positive effects of some prebiotics to alleviate constipation and treat hepatic encephalopathy. Interesting aspects, but with a lower level of evidence at the present time, include prevention of colon cancer, intestinal infection, and recurrence of inflammatory bowel disease. There is a high level of evidence for positive effects of some probiotics in the alleviation of lactose intolerance, antibiotic-associated intestinal disorders and gastroenteritis. Evidence is rapidly growing regarding the prevention of recurrence of inflammatory bowel diseases. Positive trials have suggested preventive effects against intestinal colonization with specific gut pathogens including Clostridium difficile and Helicobacter pylori.

Bifidobacterium↗
PubMed2002

Influence of diet on the occurrence of some bacteria in the intestinal flora of wild and pet birds.

Enterobacteriaceae, E. coli in particular, do not belong to the intestinal flora of granivorous pet birds. This is indicated by the fact that the feces of only 9% of healthy budgerigars and 17% of finches tested were positive for enterobacteria. Stressful situations such as overcrowding in small cages coincident with increased noise and low light levels can enhance the colonization of the gut with E. coli. On the other hand it seems nearly impossible to colonize the intestine of budgerigars with E. coli or Klebsiella spp. even under favourable conditions. The frequent findings of enterobacteria in deceased granivorous birds suggest that E. coli and other enterobacteria are involved in the course of diseases with predisposing factors. Nutritional experiments with young chickens suggest that a diet consisting exclusively of seeds has an inhibitory effect on intestinal colonization with E. coli. Determination of Aeromonas hydrophila in nearly 3500 wild and pet birds provides statistically significant evidence that the composition of the intestinal flora may depend on dietary habits: infection was found in 1.9% of the granivorous and herbivorous species, in 7.1% of the omnivorous and in 12.4% of the carnivorous and insectivorous birds. The occurrence of enterobacteria and Aeromonas hydrophila in the digestive tract is obviously influenced by the composition of the nutrients.

Aeromonas hydrophila↗
PubMed1983

Altered colonizing ability for mouse large intestine of a surface mutant of a human faecal isolate of Escherichia coli.

Escherichia coli F-17 Sr a human faecal isolate, is resistant to the T-series of bacteriophages (i.e. T2 to T7). A T2-sensitive mutant of E. coli F-17 Sr was isolated following acriflavin treatment. This mutant, E. coli F-17 Sr Ts was found to be sensitive to the entire T-series of phages. E. coli F-17 Sr and E. coli F-17 Sr Ts did not differ quantitatively in total LPS content. However, analysis of LPS revealed that a large fraction of E. coli F-17 Sr Ts was devoid of O-side-chains. This accounted for the sensitivity of this strain to bacteriophages T3, T4, and T7. In addition, E. coli F-17 Sr Ts contained only about half the amount of capsular material contained by E. coli F-17 Sr accounting for the sensitivity of the mutant to bacteriophages T2, T5, and T6. Although the two strains colonized equally well when fed individually to streptomycin-treated mice, when fed simultaneously to streptomycin-treated mice, E. coli F-17 Sr Ts colonized at a level of about 1 x 10(8) cells (g faeces)-1, whereas E. coli F-17 Sr colonized at only 1 x 10(4) cells (g faeces)-1. These studies suggest that bacterial cell surface components modulate the large intestine colonizing ability of E. coli F-17 Sr in the mouse large intestine.

Absorption↗
PubMed1985

Hyperenteroglucagonaemia and small intestinal mucosal growth after colonic perfusion of glucose in rats.

Beside intraluminal factors, humoral agents play an important role in intestinal adaptation. Enteroglucagon, the mucosal concentration of which is maximal in the terminal ileum and colon, is the strongest candidate for the role of small intestinal mucosal growth factor. The present experiment was designed to study the role of colonic enteroglucagon in stimulating mucosal growth in rats with a normal small intestine. After eight days of glucose large bowel perfusion, enteroglucagon plasma concentrations were 120.7 +/- SEM 9.2 pmol/l, versus 60.1 +/- 6.8 in mannitol perfused control rats (p less than 0.001). Gastrin, cholecystokinin, neurotensin, pancreatic glucagon, and insulin plasma concentrations were unchanged. Crypt cell proliferation, measured by the vincristine metaphase arrest technique, increased significantly in the small intestine of glucose perfused animals (p less than 0.005-0.001) in comparison with the controls. This resulted in a greater mucosal mass in both proximal and distal small bowel: mucosal wet weight, DNA, protein and alpha D-glucosidase per unit length intestine were all significantly higher (p less than 0.05-0.001) than in mannitol perfused rats. Our data, therefore, support the hypothesis that enteroglucagon is an enterotrophic factor and stress the possible role of the colon in the regulation of small bowel trophicity.

Animals↗
PubMed2002

Apolipoprotein E and colon cancer. Expression in normal and malignant human intestine and effect on cultured human colonic adenocarcinoma cells.

Background: Apolipoprotein E (apo E) is a key regulatory protein in lipoprotein metabolism and it is also a potent inhibitor of cell proliferation. Although genetic alterations of apo E affect enterohepatic cholesterol transport and, presumably, the risk of colon carcinoma, the expression and potential functions of apo E in the human intestine are poorly known. Methods: The localization of apo E in normal and malignant gastrointestinal tract was studied using immunohistochemistry and in situ hybridization. The effect of apo E3 on cell polarity and the distribution of beta-catenin was examined in HT29 human colon adenocarcinoma cell lines. Results: Both apo E protein and mRNA were present throughout human intestine. The macrophages in the superficial lamina propria of normal colon were more strongly positive for apo E than those in the small intestine, where the most positively stained cells were dendritic cells and macrophages in the germinal centers of lymphoid follicles. In carcinomas, intensely positive macrophages surrounded the tumor area. In cultured undifferentiated HT29 cells, treatment with apo E improved cell polarity and translocated beta-catenin from the cytoplasm to cell--cell adhesion sites. Conclusions: Mononuclear phagocytes and endocrine cells are the main source of apo E in the gastrointestinal tract. We hypothesize that macrophage-derived apo E may modulate epithelial integrity and thus contribute to cell growth.

Journal Article↗
PubMed1985

Comparison of healing in the left colon and ileum. Changes in collagen content and collagen synthesis in the intestinal wall after ileal and colonic anastomoses in the rat.

Collagen metabolism was compared after anastomosis in the small and large intestine of rats. Animals were sacrificed 2 and 4 days postoperatively, when three standardized biopsy specimens were taken on either side of the anastomosis. In one group of rats, anastomosis was performed in both ileum and colon and 3H L-proline was given 24 hours before sacrifice, for studies of collagen synthesis. Animal weight, specimen dry weight, collagen concentration, collagen content per standardized biopsy, specific activity of collagen and total radioactivity were measured. Weight loss was greater after colon than after ileum anastomosis, indicating that the rats were more severely affected by colon surgery than by comparable operations on the ileum. Collagen content increased earlier and more in large intestinal than in small intestinal wall. The earlier activation of collagen synthesis in colon may have been related to differences in intestinal contents (e.g. bulk or bacteria).

Animals↗
PubMed1991

[Measurement of gastric emptying, intestinal transit time and colonic filling by scintiscan in healthy subjects].

A scintigraphic technique allowing combined measurements of gastric emptying, small intestinal transit time and colonic filling was developed and its reproducibility assessed in 8 healthy volunteers. Each subject underwent four tests: a) two were performed in the fasting state (99mTc labelled water, added to lactulose), b) two in the postprandial state (balanced meal, 1,750 kJ, included pellets labelled with 111In, the gut transit of which being nearly the same as dietary fibers). Intestinal transit was modeled using linear operators (expressed as a convolution product). In fasting state (lactulose), orocecal transit time of water was 109 +/- 60 min and 89 +/- 36 min (m +/- DS) for the first and second tests, respectively. In the postprandial state, values were 297 +/- 37 min and 293 +/- 43 min respectively for the pellets. Small bowel transit times were 135 +/- 70 and 103 +/- 40 min respectively in fasting state for water, and 209 +/- 47 and 209 +/- 29 min respectively in postprandial state for the pellets. Determination of residual variance showed that reproducibility of the test was better in the postprandial state than in the fasting state. Water orocecal transit times measured using this technique and lactulose orocecal transit time measured using hydrogen breath test were strongly correlated (r = 0.98, n = 12, P less than 0.01). This isotopic method provides a reproducible assessment of gastric emptying, small bowel transit, and colonic filling and could represent a reliable and non invasive tool for further physiological and pharmacological studies.

Adult↗
PubMed1994

Degradation of polyphenols (catechin and tannic acid) in the rat intestinal tract. Effect on colonic fermentation and faecal output.

Low- and intermediate-molecular-weight polyphenols are usually extracted by using different solvents (e.g. water, methanol, aqueous acetone). The aim of the present work was to study the possible effects of some extractable polyphenols (EPP) on fat and protein digestibilities and on the colonic microflora. Degradability of these compounds through the intestinal tract was also studied. Catechin and tannic acid (TA) were chosen as representatives of the most common basic structures of EPP (flavonoids and gallic acid respectively). Three groups of eight male Wistar rats were given either a control diet free of EPP, or diets containing 20 g/kg dry matter of catechin and TA. Body-weight and food intake were monitored during a 3-week experimental period. Faeces and urine were collected daily during the third experimental week. EPP and fat were determined in faeces, and N in both urine and faeces. Only 3.1 and 4.6% of the ingested catechin and TA respectively were excreted in faeces, indicating that absorption and/or degradation of these EPP had occurred. HPLC analysis of the polyphenolic content of faeces showed qualitative differences between groups. A significant increase of total faecal weight as well as water, fat and N excretion was produced by TA. Catechin only caused an increase in fat excretion. In vitro fermentation assays were also performed to study the effect of EPP on the colonic microflora. Both catechin and TA affected the yield of end-products of fermentation, and were also degraded during the fermentation process.

Animals↗
PubMed2000

Proteomic analysis of colonic crypts from normal, multiple intestinal neoplasia and p53-null mice: a comparison with colonic polyps.

In order to observe cellular changes caused by mutation of the tumor suppressors, APC and p53, we have generated protein expression profiles of mouse colon epithelial cells using two-dimensional electrophoresis (2-DE). Crypts, polyps and stroma were isolated from normal, multiple intestinal neoplasia (MIN) and p53-null mice, each with a C57Black/6J background, and subjected to 2-DE in two separate pH ranges (pH 3-10 and pH 6-11). No significant differences in protein expression patterns were observed between the normal, MIN and p53-null colon epithelial crypts. However, 64 proteins from the MIN polyps showed a 2-fold or greater difference in intensity that was statistically significant as assessed by the Wilcoxon rank-sum test (p < or = 0.05). Of these, calreticulin, carbonic anhydrase I and a new member of the glutathione-S-transferase theta family of proteins have so far been identified using an in-gel digestion protocol coupled with reversed-phase high performance liquid chromatography (RP-HPLC) ion-trap mass spectrometry. In addition, 38 marker proteins have been identified in a continuing effort to generate a comprehensive 2-DE database of proteins expressed by mouse colon epithelial cells (these databases are available at http://www.ludwig.edu.au/jpsl/jpslhome. html).

Animals↗