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At least 811 records · Page 45Linked to original sources
PubMed1988

A novel marker glycoprotein for the microvillus membrane of surface colonocytes of rat large intestine and its presence in small-intestinal crypt cells.

Murine mAbs were produced against purified microvillus membranes of rat colonocytes in order to establish a marker protein for this membrane. The majority of antibodies binding to the colonic microvillus membrane recognized a single protein with a mean apparent Mr of 120 kD in both proximal and distal colon samples. The antigen is membrane bound as probed by phase-partitioning studies using Triton X-114 and by the sodium carbonate extraction procedure and is extensively glycosylated as assessed by endoglycosidase F digestion. Localization studies in adult rats by light and electron microscopy revealed the microvillus membrane of surface colonocytes as the principal site of the immunoreaction. The antigen was not detectable in kidney or liver by immunoprecipitation but was present in the small intestine, where it was predominantly confined to the apical membrane of crypt cells and much less to the microvillus membrane of differentiated enterocytes. During fetal development, the antigen appears first in the colon at day 15 and 1-2 d later in the small intestine. In both segments, it initially covers the whole luminal surface but an adult-like localization pattern develops soon after birth. The antibodies were also used to develop a radiometric assay for the quantification of the antigen in subcellular fractions of colonocytes in order to assess the validity of a previously developed method for the purification of colonic brush-border membranes (Stieger, B., A. Marxer, and H.P. Hauri. 1986. J. Membr. Biol. 91:19-31.). The results suggest that we have identified a valuable marker glycoprotein for the colonic microvillus membrane, which in adult rats may also serve as a marker for early differentiation of enterocyte progenitor cells in small-intestinal crypt cells.

Age Factors↗
PubMed1985

Dietary fiber and intestinal adaptation: effects on intestinal and pancreatic digestive enzyme activities.

Male Wistar rats were fed for four weeks on defined diets containing no fiber additions, 10% levels of insoluble fiber derivatives (cellulose or alfalfa), or 5% levels of viscous fiber derivatives (pectin, guar gum, or metamucil). After an overnight fast, the pancreas was assayed for protein, amylase, lipase, trypsin, and chymotrypsin. Homogenates of small intestinal mucosa were analyzed for protein, alkaline phosphatase, invertase and thymidine kinase. There were, with few exceptions, no dietary effects on the exocrine pancreatic enzymes. The specific activities of the villus marker enzymes (invertase and alkaline phosphatase) tended to be higher in the proximal (but not middle or distal) intestines of the fiber-fed groups, while total activities were the same in all groups. In contrast, the activity of the crypt marker, thymidine kinase, was highest in the distal intestinal segments, and even higher in animals given the alfalfa, guar gum or metamucil-supplemented diets.

Adaptation, Physiological↗
PubMed1996

A total parenteral nutrition solution supplemented with a nucleoside and nucleotide mixture sustains intestinal integrity, but does not stimulate intestinal function after massive bowel resection in rats.

The effects of supplementing a total parenteral nutrition solution with a nucleoside and nucleotide mixture on mucosal adaptive processes after massive bowel resection were studied. Male Wistar rats (n=30) underwent 80% small intestine resection, were randomized into two groups and received either standard total parenteral nutrition (TPN) or TPN supplemented with a nucleoside and nucleotide mixture (2.5 mL.kg-1.d-1). An additional five rats, fed a nonpurified diet and not resected, were used as controls. After 4 or 7 d, rats were killed and samples were collected for mucosal indices and intestinal enzymatic activities (disaccharidases and diamine oxidase). After massive small bowel resection and TPN, residual jejunal mucosal wet weights, villus heights, protein and RNA contents on d 4 and 7, and total wet weights and DNA contents on d 7 were significantly lower than in the control group. Administration of the nucleoside and nucleotide mixture resulted in significantly higher residual jejunal total and mucosal weights, proteins, DNA, RNA contents, and the ratio of proliferating cell nuclear antigen positive cells per crypt than did the standard TPN solution on d 7. However, disaccharidase and diamine oxidase activities were not affected by supplementation with the nucleoside and nucleotide mixture. Our data suggest the supplementation of a nucleoside and nucleotide mixture to a TPN solution can attenuate the initial mucosal atrophy and improve intestinal cell turnover after massive bowel resection, but the supplementation has little effect on enterocyte enzymatic activities.

Amine Oxidase (Copper-Containing)↗
PubMed1999

D-tagatose has low small intestinal digestibility but high large intestinal fermentability in pigs.

The digestibility of D-tagatose, its effect on the digestibility of macronutrients and the metabolic response of the microbiota of the gastrointestinal tract to the ingestion of this carbohydrate were studied in pigs. Eight pigs were fed a low fiber diet comprising 15% sucrose (control group). Another eight pigs were fed a similar diet except that 100 g sucrose per kg diet was replaced by D-tagatose (test group). After 18 d, the pigs were killed and the gastrointestinal contents removed for analysis. The digestibility of D-tagatose was 25.8 +/- 5.6% in the distal third of the small intestine. The small intestinal digestibilities of dry matter (86.9 +/- 1.3 vs. 92.9 +/- 0.9%), gross energy (74.4 +/- 1.6 vs. 80.7 +/- 1.8%) and sucrose (90.4 +/- 2.5 vs. 98.0 +/- 0.5%) were lower (P < 0. 05) in the pigs fed D-tagatose. Digestibilities of starch, protein and fat did not differ between groups. D-Tagatose, sucrose and starch were fully digested in the large intestine. The fecal digestibilities of energy, dry matter and fat did not differ between the two groups, whereas D-tagatose reduced the fecal digestibility of protein (91.1 +/- 0.6 vs. 93.5 +/- 0.7%, P < 0.05). D-Tagatose served as a substrate for the microbiota in the cecum and proximal colon as indicated by a reduced pH, and a greater ATP concentration, adenylate energy charge (AEC) ratio and concentration of short-chain fatty acids. In particular, the increase in the concentrations of propionate, butyrate and valerate suggests possible health benefits of this monosaccharide.

Adenosine Triphosphate↗
PubMed2004

Onset of small intestinal atrophy is associated with reduced intestinal blood flow in TPN-fed neonatal piglets.

Our aim was to determine the speed of onset of total parenteral nutrition (TPN)-induced mucosal atrophy, and whether this is associated with changes in intestinal blood flow and tissue metabolism in neonatal piglets. Piglets were implanted with jugular venous and duodenal catheters and either a portal venous or superior mesenteric artery (SMA) blood flow probe. At 3 wk of age, piglets were randomly assigned to receive continuous enteral formula feeding (n = 8) or TPN (n = 17) for 24 or 48 h. Blood flow was recorded continuously and piglets were given an i.v. bolus of bromodeoxyuridine and (13)C-phenylalanine to measure crypt cell proliferation and protein synthesis, respectively. After 8 h of TPN, portal and SMA blood flow decreased 30% compared with enteral feeding (P < 0.01), and remained near levels of food-deprived piglets for the remaining 48 h of TPN. After 24 h, TPN reduced jejunal inducible nitric oxide synthase (iNOS) activity and protein abundance (P < 0.05), small intestinal weight, and villous height (P < 0.01) compared with enterally fed piglets. Cell proliferation and DNA mass were decreased (P < 0.05) and apoptosis increased (P < 0.05) after 48 h of TPN. Protein synthesis was lower (P < 0.05) after 24 h of TPN, and protein mass was lower (P < 0.05) after 48 h of TPN, compared with enteral feeding. These data indicate that the transition from enteral to parenteral nutrition induced a rapid (<8 h) decrease in intestinal blood flow, and this likely precedes villous atrophy and the suppression of protein synthesis at 24 h, and of cell proliferation and survival at 48 h.

Animals↗
PubMed1981

Hypersensitivity reactions in the small intestine. 6. Pathogenesis of the graft-versus-host reaction in the small intestinal mucosa of the mouse.

The intestinal phase of the graft-versus-host reaction (GVHR) has been investigated in adult F1 mice bearing grafts of fetal gut using an H-2-incompatible and an H-2-compatible, Mls-incompatible combination. The results indicate that the mitotic activity of the intestinal crypts and the number of intraepithelial lymphocytes are sensitive parameters of the mucosal cell-mediated immune response in the GVHR. Using these indices, indirect evidence has been obtained that soluble factors may be responsible for the damage to the intestine in the GVHR. Possible pathways of lymphocyte activation and migration to the gut are proposed to explain the role of gut-associated T cells in the production of these mediators.

Animals↗
PubMed1975

Changes in intestinal cell kinetics in the small intestine of lactating mice.

The enlargement of the small intestine of mice during lactation is due, at least in part, to hyperplasia in the mucosal crypts and villi. The number of cells per crypt increases by 130% and the cell production rate by 63% after 15 days of lactation. These parameters were measured from crypt squashes and sections using both double-label and PLM techniques. Neither the numbers of crypts and villi in the small intestine nor the turnover time of post-mitotic cells on the villi changed. A number of factors appear to act in concert during lactation to trigger this increase in epithelial cell number in the small intestine. The experiments reported suggest a role for the increased quantity of food consumed by the lactating animal, for changing hormonal levels, and for the increased demands placed on the body by milk production.

Animals↗
PubMed1975

Existence of two chalone-like substances in intestinal extract from the adult newt, inhibiting embryonic intestinal cell proliferation.

The inhibiting effect of tissue extract from fully differentiated intestinal mucosa of adult animals on proliferation kinetics of exponentially growing embryonic epithelial gut cell populations was studied in the newt Pleurodeles waltlii. Crude extract was fractionated by G-200 Sephadex chromatography and the effect of fractions on cell proliferation was studied using both mitotic index and 3-H-thymidine incorporation methods. The inhibitions we obtained were then displayed by means of cytophotometric study of age distribution of intestinal gut cells around the cell cycle, measuring the Feulgen-DNA content. The results revealed the presence of two chalone-like substances in the intestine of adults. One (factor 1) is characterized by a molecular weight of between 120,000 and 150,000 and inhibits the cell cycle at the end of the G1 phase, the other (factor 2) is characterized by a molecular weight lower than 2000 and inhibits the cell cycle in the course of the G2 phase. The cells delayed in the G2 phase escape from inhibition but the cells delayed in the G1 phase do not, although availability time of both factor 1 and factor 2 is about 12 hr. It is thus thought that cells prevented from dividing in G1 phase are indefinitely delayed in this phase and possibly differentiate.

Animals↗
PubMed2005

Shigella flexneri infection is dependent on villin in the mouse intestine and in primary cultures of intestinal epithelial cells.

Villin is an actin-binding protein present in intestinal and kidney brush borders. Villin has been shown to present in vitro Ca(2+)-dependent bundling and severing F-actin properties. The study of villin knock-out mice allowed us to show that while bundling of F-actin microfilaments is unaffected, this protein is important for the reorganization of the actin cytoskeleton elicited by various signals during both physiological and pathological conditions. Here, we studied the role of villin during infection by Shigella flexneri, the causative agent of bacillary dysentery. This bacterium induces the reorganization of the host actin cytoskeleton to penetrate into epithelial cells and spread from cell to cell. In vivo, we show that unlike newborn vil+/+ mice, which are sensitive to Shigella invasion, resulting in a destructive inflammatory response of the intestinal mucosa following intragastric inoculation, newborn vil-/- mice appear fully resistant to infection. Using primary cultures of intestinal epithelial cells derived from vil+/+ or vil -/- mice, we demonstrate that villin plays an essential role in S. flexneri entry and cell-to-cell dissemination. Villin expression is thus critical for Shigella infection through its ability to remodel the actin cytoskeleton.

Actins↗
PubMed1999

The roles of P-glycoprotein and intracellular metabolism in the intestinal absorption of methadone: in vitro studies using the rat everted intestinal sac.

Methadone is used as a treatment for opiate detoxification in methadone maintenance programs. Intra- and inter-patient variations in methadone bioavailability have been observed after oral methadone treatment and this makes it difficult to predict a dosing regimen. Intestinal absorption and metabolism could explain these variations. The in vitro gut sac model was used to study the intestinal absorption of methadone, and it confirmed that methadone is a substrate for P-glycoprotein. The transport of methadone was increased in presence of P-gp inhibitors verapamil and quinidine. The appearance of a major metabolite of methadone, 2-ethylidene-1, 5-dimethyl-3, 3-diphenyl pyrrolidine (EDDP) in the gut sac contents also demonstrated the existence of intestinal metabolism of methadone.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1984

Effects of p-chlorophenylalanine on the sensitivity of rat intestine to agonists and on intestinal 5-hydroxytryptamine levels during Nippostrongylus brasiliensis infection.

Infection of rats with the nematode N. brasiliensis caused non-specific increases in maximum response of isolated intestine to acetylcholine and 5-hydroxytryptamine (5-HT), and a specific subsensitivity to 5-HT. Intestinal levels of 5-HT, measured fluorimetrically, increased approximately 2 fold during infection. Treatment of infected rats with parachlorophenylalanine (PCPA) depleted the gut of 5-HT, and prevented the specific subsensitivity to the amine but not the increases in maximum response. Depletion of intestinal 5-HT did not prevent the immune expulsion of the parasites. It is concluded that the specific subsensitivity of the gut is due to the elevated levels of 5-HT during infection, but that the increased maximum responses are due to some other factor. Further, the lack of effect of PCPA on parasite rejection casts doubt on the proposed role of 5-HT in this process.

Acetylcholine↗
PubMed2004

Intestinal transplantation for chronic intestinal pseudo-obstruction in adult patients.

Intestinal transplantation (ITx) has become a life-saving procedure for patients with irreversible intestinal failure who can no longer be maintained on parenteral nutrition (PN). This report presents the results of our experience on ITx in patients suffering from chronic intestinal pseudo-obstruction (CIPO). Between December 30, 2000 and May 30, 2003 six adult patients affected by CIPO underwent primary ITx at our Center. Pre-transplant evaluation, indication for ITx and surgical technique are reported. On December 30 2003, the mean follow-up was 25.0 months. No peri-operative deaths occurred in the study population and five out of six patients are alive, with 1-year patient and graft survival of 83.3% and 66.6%. Although our series is limited by the number of patients, our experience suggests that ITx transplantation should be considered in adult patients suffering from CIPO and PN life-threatening complication.

Adult↗
PubMed1983

Membranous glomerulopathy and chronic small-intestinal enteropathy associated with autoantibodies directed against renal tubular basement membrane and the cytoplasm of intestinal epithelial cells.

A child with an immune-mediated disease is described, who presented two very rare clinical manifestations, a membranous glomerulopathy with circulating anti-renal tubular basement membrane antibody and a small-intestinal enteropathy with circulating antibody directed against the cytoplasm of intestinal epithelial cells. Steroid treatment was followed by complete resolution of the renal but not the intestinal manifestations.

Autoantibodies↗
PubMed1995

Substance P effects on blood flow, fluid transport and vasoactive intestinal polypeptide release in the feline small intestine.

1. Substance P (SP) infusions were given close I.A. to the feline small intestine in vivo in a dose that produced plasma concentrations of 1-5 microM. This infusion regularly evoked a net fluid secretion measured with a gravimetric technique. Concomitantly, the release into blood of vasoactive intestinal polypeptide (VIP), a putative neurotransmitter of the enteric nervous system, increased. 2. The SP-induced fluid secretion was blocked by tetrodotoxin (7 micrograms close I.A.), a blocker of fast sodium channels in excitable tissues, and hexamethonium (10 mg (kg body wt)-1, I.V.), a nicotinic receptor antagonist, suggesting that the SP effect was mediated by the enteric nervous system. In line with this it was shown that the SP-evoked release of VIP was also significantly diminished by hexamethonium. 3. Close I.A. infusions of methionine enkephalin (Met-enkephalin; 7-23 nmol min-1) or electrical stimulation of the sympathetic nerve fibres (6 Hz) to the intestine markedly diminished net fluid secretion and the release of VIP caused by SP given close I.A. 4. The cyclo-oxygenase inhibitor diclofenac (5 mg (kg body wt)-1, I.V.) or the histamine-1 receptor antagonist pyrilamine (10 mg (kg body wt)-1, I.V.) did not influence the fluid secretion caused by SP, indicating that the effects of SP were not due to the actions of prostaglandins or histamine. 5. It is proposed that SP activates a nervous reflex arch that we have shown to be activated by various luminal stimuli, including cholera toxin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Importance of the intestinal inflammatory reaction in salmonella-mediated intestinal secretion.

The ability of Salmonella typhimurium to invade the intestinal epithelium is essential to the pathogenesis of salmonella-induced intestinal secretion. This invasion is accompanied by an intense acute inflammatory reaction. The present study tests the hypothesis that the acute inflammatory reaction may have a role in the pathogenesis of salmonella-induced secretion. Two groups of rabbits infected with S. typhimurium were studied: normal animals and animals pretreated with nitrogen mustard. Nitrogen mustard depletes the polymorphonuclear leukocyte pool and thereby prevents the formation of an acute inflammatory reaction. In vivo ligated ileal loops were constructed and infected 72 h after nitrogen mustard administration when polymorphonuclear leukocytes were undetectable. Nitrogen mustard treatment markedly inhibited salmonella-induced secretion. Ileal histology in normal animals infected with S. typhimurium revealed an intense acute inflammatory reaction, while in animals pretreated with nitrogen mustard only a rare polymorphonuclear leukocyte was seen. The antisecretory effect of nitrogen mustard was not merely a nonspecific effect since nitrogen mustard treatment did not inhibit cholera toxin-induced secretion and did not alter either ileal morphology nor the activities of various intestinal enzymes in normal animals. Nitrogen mustard also did not alter the virulence of the inoculated S. typhimurium. These data suggest that the mucosal inflammatory reaction induced by salmonella invasion may be important to the pathogenesis of the salmonella secretory process. The mechanism by which the inflammatory reaction stimulates secretion is not known.

Animals↗
PubMed1983

A pathophysiological study of the intestinal manifestations of a vasoactive intestinal peptide, calcitonin, and catecholamine-secreting tumour.

A three year old girl with severe watery diarrhoea and a vasoactive intestinal peptide, calcitonin, and catecholamine-secreting supra-renal ganglioneuroblastoma is reported. Steady-state perfusion studies showed the jejunum to be in a net secretory state with respect to water, sodium, and chloride at low concentrations (2 mmol/l) of glucose whereas higher concentrations (56 mmol/l) reversed secretion to absorption; transmural rectal potential difference was increased (lumen negative); Na+ absorption by the rectum was impaired and secretion of potassium and bicarbonate excessive. Motility studies showed prolonged, slowly propagated migrating motor complexes with abnormal runs of non-propagated contractions in the fasting state. During perfusion with glucose, no postprandial activity occurred. These results suggest that diarrhoea results from small intestinal secretion with impaired colonic function and that tumour products may have a direct effect on intestinal motility.

Adrenal Gland Neoplasms↗
PubMed2003

The locally acting glucocorticosteroid budesonide enhances intestinal sugar uptake following intestinal resection in rats.

BACKGROUND AND AIMS: Locally and systemically acting corticosteroids alter the morphology and transport function of the intestine. This study was undertaken to assess the effect of budesonide, prednisone, and dexamethasone on sugar uptake. METHODS: Adult male Sprague Dawley rats underwent transection or resection of 50% of the middle portion of the small intestine, and in vitro uptake of sugars was measured. RESULTS: The 50% enterectomy did not alter jejunal or ileal uptake of glucose or fructose. Prednisone had no effect on the uptake of glucose or fructose in resected animals. In contrast, in resected rats budesonide increased by over 120% the value of the jejunal maximal transport rate for the uptake of glucose, and increased by over 150% ileal uptake of fructose. Protein abundance and mRNA expression of the sodium dependent glucose transporter in brush border membrane (SGLT1), sodium independent fructose transporter in the brush border membrane (GLUT5), sodium independent glucose and fructose transporter in the basolateral and brush border membranes (GLUT2), and Na(+)/K(+) ATPase alpha1 and beta1 did not explain the enhancing effect of budesonide on glucose or fructose uptake. Budesonide, prednisone, and dexamethasone reduced jejunal expression of the early response gene c-jun. In resected animals, expression of the mRNA of ornithine decarboxylase (ODC) in the jejunum was reduced, and corticosteroids reduced jejunal expression of the mRNA of proglucagon. CONCLUSIONS: These data suggest that the influence of corticosteroids on sugar uptake in resected animals may be achieved by post translational processes involving signalling with c-jun, ODC, and proglucagon, or other as yet unknown signals. It remains to be determined whether budesonide may be useful to stimulate the absorption of sugars following intestinal resection in humans.

Animals↗
PubMed1986

An analysis of intestinal calcium transport across the rat intestine.

Kinetic analysis of transmural calcium transport, as evaluated by in situ intestinal loops, has confirmed the existence of two transport processes, a saturable, transcellular one that is regulated by vitamin D and predominates in the proximal intestine and a nonsaturable process similar in intensity throughout the intestine. Transport data obtained from everted sac experiments are kinetically consistent with events in the in situ loop. Analysis of the three component steps making up the saturable process, i.e., entry across the brush-border membrane, intracellular diffusion, and extrusion across the basolateral membrane, indicates that intracellular diffusion is likely to be the limiting step. Active calcium transport varies directly and proportionately with the content of calcium-binding protein (CaBP), a specific molecular expression of the action of vitamin D. Since CaBP is a cytosolic protein, it may act to facilitate calcium diffusion, a proposition advanced by Kretsinger, Mann, and Simmons and supported here quantitatively. We calculate that the rate of intracellular calcium diffusion in the absence of CaBP is only approximately 1/70 of what is found in the vitamin D-replete cell. Similar considerations have led to the proposal that calcium moved by the nonsaturable process travels largely via the paracellular route. The kinetic parameters derived here, i.e., Vm = 22 mumol X h-1 X g (wt wt-1, Km = 3.9 mM, and a nonsaturable rate of 0.16/h, can be used to predict calcium absorption data as determined in previously published balance experiments.

Aging↗