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PubMedDate not supplied

Effects of dietary fiber on the rat intestinal mucosa exposed to low doses of a carcinogen.

BACKGROUND: Changes in morphological and immunohistochemical parameters were studied in the rat intestinal mucosa exposed to low doses of a carcinogen and administered with dietary fibers. METHODS: Tumors were induced by five subcutaneous injections of 1,2-dimethylhydrazine, 10 mg/kg rat, once a week. Rats were fed a semi-synthetic fiber-free diet (control) or a high-fiber diets (15%) derived from cellulose, tomato peels or white grape. The rats were sacrificed 24 weeks after the first carcinogen's injection. The ileum, colon and tumors were removed for the study. Areas of the mucosal stroma and of lymph infiltrations, and mitotic index were studied along with morphological parameters. Immunohistochemical parameters included determination of Ki-67 proliferating protein and apoptotic index. RESULTS: Areas of the stroma in colon tumors increased in rats fed tomato peels. Changes in areas of lymphoid infiltrates were related to the type of diet and tumor presence. Lymphoid infiltrations were found to be highly developed in the colon area close to tumors, especially in rats fed the white-grape diet. Mitotic index and Ki-67 protein increased significantly in the colon area close to a tumor and in tumors themselves without any relation to the fiber varieties consumed. Changes in the rate of apoptosis were not related to the preventive effect of diets: apoptotic index was high in tumors obtained from rats fed the high-cellulose diet with high tumor-preventive effects and also from rats fed the high-tomato-peel diet with low tumor-preventive effects. CONCLUSIONS: No morphological changes were found in the ileum of rats exposed to a carcinogen and fed different dietary fibers. In the colon, a carcinogen even in low concentrations inhibited the lymphoid system in the mucosa located far from the tumor or close to the tumor. An increase in the proliferation rate in the colon close to the tumor may reflect the development of precanceromatous processes or may be related to the effect of growth factors expressed by tumor cells. Finding adenoma-like dysplasia near tumors may be possible in early stages of the development of new tumors. In addition, activation of the lymphoid system of the colon following consumption to specific dietary fiber may be a mechanism by which fiber protect against cancer.

1,2-Dimethylhydrazine↗
PubMed1989

Enzymatic conversion of all-trans-beta-carotene to retinal by a cytosolic enzyme from rabbit and rat intestinal mucosa.

Enzymatic conversion of all-trans-beta-carotene to retinal by a partially purified enzyme from rabbit and rat intestinal mucosa was demonstrated. The enzymatic product was characterized based on the following evidence: (i) The product gave rise to its O-ethyloxime by treatment with O-ethylhydroxylamine with an absorption maximum at 363 nm in ethanol characteristic of authentic retinal O-ethyloxime. High-pressure liquid chromatography (HPLC) of this derivative yielded a sharp peak with a retention time of 7.99 min corresponding to the authentic compound. The enzyme blank and boiled enzyme blank failed to show any significant HPLC peaks corresponding to retinal O-ethyloxime, retinal, or retinol. (ii) The mass spectrum of the O-ethyloxime of the enzymatic product was identical to that of authentic retinal O-ethyloxime (m/z 327: 45%, M+. and m/z 282: 100%, M--ethoxy). (iii) The specific activity of the enzymatically formed [14C]retinal O-ethyloxime remained constant even after repeated crystallization. (iv) The enzymatic product exhibited an absorption maximum at 370 nm in light petroleum characteristic of authentic retinal. Furthermore, it was reduced by horse liver alcohol dehydrogenase to retinol with an absorption maximum at 326 nm in light petroleum. This retinol was enzymatically esterified to retinyl palmitate by rat pancreatic esterase with a retention time of 10 min on HPLC corresponding to authentic retinyl palmitate. Thus, the enzymatic product of beta-carotene cleavage by the partially purified intestinal enzyme was unequivocally confirmed to be retinal.

Animals↗
PubMed1981

Enzymic esterification of cholesterol in rat intestinal mucosa catalyzed by acyl-CoA: cholesterol acyltransferase.

Previous work has shown CoA-dependent esterification of cholesterol in rat intestinal mucosa. Using (1-(14)C)oleoyl-CoA as the labeled substrate, we have proved that the esterification is catalyzed by acyl-CoA: cholesterol acyltransferase (ACAT) existing in the 'microsomal fraction' of the mucosal cell. The apparent K(m) for oleoyl-CoA is 25 microM, the optimal pH 7.4-7.9, and the optimal concentration of albumin 10-20 mg/ml. The reaction is rectilinear for only 2 min. Increasing the microsomal cholesterol concentration by incubation with plasma from patients with familial lecithin: cholesterol acyltransferase deficiency leads to increasing ACAT activity. The ACAT was inhibited by taurocholate and by the thiol-blocking agent 5,5'-dithiobis(2-nitrobenzoic acid). The specific activity of the enzyme is high-that is, approximately 1 nmol cholesteryl oleate formed x mg microsomal protein(-1) x min(-1).

Animals↗
PubMed1969

Vitamin A and carotenoids. The enzymic conversion of beta-carotene into retinal in hog intestinal mucosa.

The conversion of beta-carotene into retinal was studied in vitro with enzyme preparations from homogenates of hog intestinal mucosa. The hog mucosal enzyme was purified about 27-fold by precipitation with ammonium sulphate, chromatography on DEAE-Sephadex and gel filtration on Sephadex G-200. The reaction displayed a narrow optimum pH range (approx. 7.8-8.2). The enzyme was stimulated strongly by the addition of thiols, and was inhibited by thiol inhibitors and by the chelating agents alphaalpha'-bipyridyl and o-phenanthroline. The reaction required the addition of an appropriate detergent (or bile salt); maximal activity was obtained by addition of an appropriate combination of detergents and lipid (specifically Tween 40, sodium glycocholate and sphingomyelin). The reaction displayed Michaelis kinetics with K(m)1.3x10(-6)m and V(max.)1.1nmole of retinal formed/hr. (for 0.7mg. of enzyme protein). The properties of the hog enzyme are similar to those previously reported for a less purified rat enzyme preparation.

Animals↗
PubMed1991

Cathepsin B and D activities in intestinal mucosa during postnatal development in pigs. Relation to intestinal uptake and transmission of macromolecules.

The mucosal activities of cathepsin B and D were assayed in the small intestine of newborn pigs and of pigs 24 h, 6 days and 4-8 weeks old, respectively. Before sacrificing these animals, the intestinal capacity to internalise and further transmit macromolecules into the blood serum was evaluated by feeding a marker solution containing bovine IgG, bovine serum albumin and fluorescein-isothiocyanate-conjugated dextran 70,000 (FITC-dextran). No significant differences in the activities of cathepsin B or D were observed in the mucosa from the various age groups of pigs. The transmission of the marker macromolecules into the blood was higher in the newborn pigs than in older postclosure animals, all of which only had low or undetectable serum marker concentrations. No apparent difference in the uptake of the markers into the intestinal epithelium could be detected between that of the newborn, preclosure pigs and pigs 24 h old. Both groups showed a similar pattern of mucosal fluorescence, indicating that there had been a high uptake of all markers into the epithelium. In the 6-day-old pigs, epithelial uptake was only visible in the distal small intestine, whereas no uptake at all could be found in the animals 4-8 weeks of age. The results suggest that intestinal closure in the pig, i.e. the dramatic decrease in the transfer of macromolecules from the intestinal epithelium in the blood at about 24 h of age, is not due to a decrease in the endocytotic ability of the enterocytes, nor to a higher degradation rate within these cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[T lymphocyte populations of the intestinal mucosa in celiac disease in children. Immunohistochemical study].

In order to study the distribution of lymphocyte subpopulations in a pathologic intestinal mucosa, the authors, instead of using the classic method by counting the number of lymphocytes, present an original method permitting the exploitation of quantified data from labelled surface cells by texture analyser coupled with a computerized system. We investigated 25 children presenting with chronic diarrhea and villous atrophy and 5 control subjects. Fifteen of the 25 children had celiac disease (10 active with total villous atrophy and 5, celiac disease in remission with healing mucosa), 5 cow's milk protein intolerance with total or partial villous atrophy and 5, chronic diarrhea with partial villous atrophy. Immunohistochemical study with monoclonal antibodies was carried out on frozen sections using a three-step immunoperoxidase technique. Compared with the 5 controls, patients with food intolerance (celiac disease and cow's milk protein intolerance) showed a significant increase of T suppressor lymphocytes (p less than 0.01 and p less than 0.05) in the epithelium, whereas there were more T helper lymphocytes in the lamina propria (p less than 0.05 and p less than 0.01). Non-treated celiac disease was distinguished from treated celiac disease by a marked increase in intra-epithelial T cytotoxic-suppressors. These results suggest that T cytotoxic-suppressors may be the mediators of the lesions observed in celiac disease.

Adolescent↗
PubMed1990

The three-dimensional organization and ultrastructure of lymphatics in the rat intestinal mucosa as revealed by scanning electron microscopy after KOH-collagenase treatment.

The three-dimensional organization and ultrastructure of lymphatics in the rat intestinal mucosa were studied by scanning electron microscopy using the KOH-collagenase digestion method (to remove extracellular connective tissue matrices) and by conventional transmission electron microscopy. Each villus possessed three or more lymphatics in the deeper layer of the lamina propria. These initial lymphatics were 5-15 microns in diameter and ran parallel to each other in the longitudinal direction of the villus. These lymphatics were free from adhering periendothelial cells, but had numerous cytoplasmic folds and projections of the endothelium on their abluminal surface. At the villous base, the lymphatics emptied into several thicker (about 70-80 microns) lymphatics, which further connected together to form a flat and wide sinus (intra-villous lymphatic sinus). This sinus was relatively smooth in abluminal surface. From the bottom of each sinus, several lymphatics descended perpendicularly to drain into lymphatics in the submucosa. The villous lymphatics described above seemed to be partially accompanied by bundles of smooth muscle cells, which ran longitudinally in the villous core. The submucosal lymphatics were smooth in abluminal surface and possessed no periendothelial cells. These lymphatics ran in a transverse direction just beneath the muscularis mucosae to form a two-dimensional mesh-work by anastomosing with one another. This submucosal lymphatic network was often closely associated with the muscle cells of the muscularis mucosae, but was not accompanied by submucosal arteries.

Animals↗
PubMed2006

Intraluminal injection of short chain fatty acids diminishes intestinal mucosa injury in experimental ischemia-reperfusion.

PURPOSE: Investigated the effect of intraluminal short-chain fatty acids (SCFA) on the intestinal mucosa in the presence of ischemia-reperfusion injury (IRI). METHODS: Six blind sacs of the small bowel (3 at the jejunum and 3 at the ileum) were created in ten Wistar rats. The lateral sacs of both bowel regions were subjected to IRI (15/15 minutes) while the medial sacs were let free to receive blood supply. In the lateral sacs, it was injected either a solution containing SCFA (butyrate, propionate and acetate) or pure saline at the bowel lumen. No fluid was injected in the medial sacs. RESULTS: Both at the jejunum and at the ileum the score of the mucosal injury was higher in saline than in control sacs. SCFA treated sacs showed lesser score at the ileum (p = 0.03) but were not significantly different at the jejunum (p = 0.83) when compared with saline sacs. It was found a significant greater number of neutrophils (p < 0.01) in the sacs treated with saline than in the other two sacs in both regions. CONCLUSION: SCFA protect the distal small bowel mucosa and diminishes infiltration of neutrophils to the gut lamina propria in IRI.

Animals↗
PubMed1985

Separation of two constitutive forms of cytochrome P-450 active in aminopyrine N-demethylation from rabbit intestinal mucosa microsomes.

Two constitutive forms of cytochrome P-450, designated P-450ib and P-450ic, were purified from intestinal mucosa microsomes of untreated rabbits. P-450ib and P-450ic have minimal molecular weights of 56 000 and 49 000, respectively, as determined by calibrated sodium dodecyl sulphate polyacrylamide gel electrophoresis. The CO-reduced difference spectral maximum of cytochrome P-450ib is at 450 nm and P-450ic is at 451 nm. Both the cytochromes preferentially demethylate aminopyrine, benzphetamine and N,N-dimethylaniline in the presence of NADPH-cytochrome P-450 reductase. Cytochrome P-450ib has absorption maxima at 417, 535 and 573 nm in the oxidized form, indicating that this cytochrome is in a low-spin state. Ouchterlony double-diffusion studies show that cytochrome P-450ib does not cross-react with antisera against liver cytochrome P-450LM2 purified from phenobarbital-treated rabbits, but P-450ic cross-reacts with spur formation. Unlike cytochrome P-450ib, P-450ic is very similar, if not identical, to liver cytochrome P-450LM2 on the basis of its molecular weight, spectral properties, catalytic activities and immunochemical properties.

Aminopyrine N-Demethylase↗
PubMed1986

A method for measuring apical glucose transporter site density in intact intestinal mucosa by means of phlorizin binding.

Phlorizin binding has been widely used to estimate the site density of glucose transporters on intestinal and renal brush-border vesicles. Glucose transport measurements in the intact intestinal mucosa show that changes in transport rate postulated to arise from changes in site density occur under many physiological and pathological conditions. Exploring the basis of these regulatory phenomena would be facilitated by comparing changes in transport rate and site density measured in the same preparation. Hence we developed methods for measuring phlorizin binding in everted sleeves of intact mouse intestine. Specific binding of phlorizin to glucose carriers reached an asymptotic value within 120 sec, while nonspecific binding continued to rise thereafter. Hence we used 120-sec incubations. The rate of dissociation of specifically bound phlorizin was accelerated by Na+-free solutions and even more by 50 mM glucose, while the rate of dissociation of nonspecifically bound phlorizin was independent of these solution changes. Hence we chose a 20-sec rinse in Ringer + 50 mM mannitol, because it washes out 30-40% of the nonspecifically bound phlorizin but virtually none of the specifically bound phlorizin. Ligand-binding analysis of specific binding against phlorizin concentration suggested two classes of binding sites, of which the one with stronger affinity for phlorizin probably has the higher capacity for glucose transport in mouse jejunum. The calculated affinity and capacity of this component are independent of whether one estimates the specific component of total binding by adding glucose or by removing Na+.

Animals↗
PubMed1984

Ultrastructure of mouse intestinal mucosa and changes observed after long term anthraquinone administration.

In an attempt to study the relative toxicity of anthraquinonic laxatives on intestinal mucosa, we compared in mice the effects of fruit pulp containing sennosides A and B with those of a free anthraquinone, 1-8 dihydroxyanthraquinone. Observations have been made with transmission electron microscopy (EM) after 16 weeks of treatment with the two drugs. Although the doses used in this study were equipotent in terms of laxative activity, no damage to the intestinal tissue was observed with the sennosides. A number of changes, however, were detected in intestinal nervous tissues of all the animals treated with 1-8 dihydroxyanthraquinone, mainly in the form of vacuolisation of the axons, formation of lysosomal structures and in some cases appearances of fibrillar degeneration.

Animals↗
PubMedDate not supplied

Histological and histochemical changes of the intestinal mucosa at the urothelial-enteric anastomotic site.

OBJECTIVE: The incorporation of bowel segments for urinary tract reconstruction may induce intestinal mucosal changes with the development of metabolic, nutritional, gastrointestinal and carcinogenic complications. The early histological and histochemical changes of the intestinal mucosa in contact with the feces-urine mixture, are evaluated in the present study. MATERIALS AND METHODS: Twelve rats (operated group) were submitted to a vesico-colonic anastomosis, and 10 rats (control group) underwent a sham operation (the colon was opened and immediately sutured). On the operated group, the left colon was divided into 3 equal portions and the middle segment was used for the bladder-colonic anastomosis. After 20 weeks, the animals were sacrificed and the entire left colon in each group, as well as the bladder and the vesico-colonic anastomosis in the operated group, was removed. The proximal, middle (anastomotic site in the operated group and sutured portion in the control group) and distal colon were used for histological and histochemical studies. RESULTS: Metaplasia, chronic inflammatory process and fibrosis were significantly greater at the anastomotic site compared to the middle segment of the control group. There were no differences in both groups in terms of dysplasia, atrophy and hypertrophy either on the proximal, middle or anastomotic area and distal portion of the left colon. All animals in the operated group showed a reduced presence of sulfomucin and an increase in the sialomucin content. CONCLUSION: The histological changes observed in this study may suggest a precancerous phenomenon.

Anastomosis, Surgical↗
PubMedDate not supplied

Differential catabolic fate of neuromedin N and neurotensin in the canine intestinal mucosa.

We have established the peptidase content of a P2 fraction (enriched in synaptosomes) and plasma membranes prepared from canine intestinal mucosa. Fourteen exo- and endopeptidases were assayed with fluorimetric or chromogenic substrates and identified by means of specific peptidase inhibitors. Post-proline dipeptidyl aminopeptidase IV, aminopeptidase M, and carboxypeptidase A were the most abundant exopeptidases, while aminopeptidases A and B, dipeptidyl aminopeptidase, pyroglutamyl peptide hydrolase I, and carboxypeptidase B displayed little, if any, activity. Endopeptidase 24.11 was the only endopeptidase that was detected in high amount. By contrast, proline endopeptidase exhibited a low activity, while angiotensin-converting enzyme, endopeptidase 24.15, endopeptidase 24.16, and cathepsin B and D-like activities were not detected. The catabolic rates of the two related neuropeptides, neurotensin (NT) and neuromedin N (NN), established that NN was inactivated 16 to 24 times faster than NT by plasma membrane and P2 fractions, respectively. Furthermore, the two peptides underwent qualitatively distinct mechanisms of degradation. A phosphoramidon-sensitive formation of NT(1-10) was detected as the major NT catabolite, indicating that NT was susceptible to an endoproteolytic cleavage elicited by endopeptidase 24.11. By contrast, NN was inactivated by the action of an exopeptidase at its N-terminus, leading to the formation of [des-Lys1]NN. The occurrence of this NN metabolite was prevented by bestatin and actinonin, but not by the aminopeptidase B inhibitor, arphamenine B, indicating that the release of the N-terminal residue of NN was likely due to aminopeptidase M.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1975

[Properties and isoenzymes of acid phosphatase in erythrocytes and various tissues (kidney, liver, spleen, small intestine mucosa, testis, myocardial and skeletal musculature) of cattle].

The substrate that was split most rapidly by acid phosphatase was p-nitrophenylphosphate. Two peaks of activity were obtained at pH 4.6-4.8 and 5.1-5.4. The enzyme remained stable for a long time when refrigerated. It was inhibited strongly by urea and tartrate, and slightly by fluoride and L-phenylalanine. Mercaptoethanol elicited pronounced activation of the enzyme. Four different forms of isoenzyme, giving rise to 11 phenotypes, were identified. A suitable analytical technique was electrophoresis on polyacrylamide gel with phosphate-citrate buffer. Mean activity was 3.15 +/- 0.41 units per gramme of haemoglobin haemolysate. Some of the isoenzyme preparations showed considerable variation in activity. There was no change in enzyme activity after temporary hypomagnesaemia. Acid phosphatase activity was high in testis, kidney and intestinal mucosa; myocardium, liver and spleen showed moderate activity. Five isoenzymes were demonstrable in a starch column and six in PAA gel.

Acid Phosphatase↗
PubMed2002

Basement membrane and connective tissue proteins in intestinal mucosa of patients with coeliac disease.

AIMS: Gluten ingestion in coeliac disease is associated with alterations of the intestinal mucosa, especially the expansion of the lamina propria. Antiendomysium and antireticulin antibodies may result from interactions between gliadin and extracellular matrix components. By behaving as autoantigens, connective tissue proteins could initiate mucosal damage. This study evaluates changes in the distribution of laminin, type IV collagen, and fibronectin in the mucosa of patients with coeliac disease in an attempt to explain the alterations of mucosal morphology. METHODS: Intestinal biopsies were obtained from patients with coeliac disease on admission and while on a gluten free diet. The distribution of type IV collagen, laminin, fibronectin, and alpha-smooth muscle actin was evaluated by immunofluorescence and by immunogold labelling and electron microscopy. RESULTS: In patients with coeliac disease, the intensity of type IV collagen, laminin, and fibronectin immunofluorescent staining was decreased and less well defined than in controls, with frequent breaches in the basement membrane; fibronectin staining was weak in the distal third of the elongated crypts and absent under the flat surface. The distribution of smooth muscle fibre in the distal lamina propria of flat mucosae was altered. The distribution of these proteins was normal as assessed by immunoelectron microscopy. CONCLUSIONS: The intensity of staining of some components of the basement membrane is decreased in coeliac disease and the distribution of smooth muscle fibres is altered. These changes may result from interactions between gliadin and components of the extracellular matrix and may play a role in the genesis of mucosal lesions and in the damage to the epithelium.

Basement Membrane↗
PubMed1984

Morphometric analysis of small intestinal mucosa. II. Determination of lamina propria volumes; plasma cell and neutrophil populations within control and coeliac disease mucosae.

Morphometric techniques were employed to measure (i) lamina propria volumes and (ii) the absolute numbers of neutrophils and plasma cells, of A, M and G isotype, within the lamina propria of jejunal mucosa. Mucosal specimens were obtained with a Watson capsule (a) from 5 patients with untreated coeliac disease, and again at least 3 months after starting on a gluten-free diet, and (b) from 9 control individuals. Lamina propria volume of untreated coeliac mucosa (2.5 +/- 0.17 X 10(6) micron3 ) was increased 2.3-fold (p less than 0.01) above that of control mucosae (1.35 +/- 0.08 X 10(6) micron3 ). Compared with control mucosae, there was a 20-fold increase of neutrophils in untreated coeliac mucosae (p less than 0.005). The total complement of all plasma cells in untreated coeliac mucosae (309) was twice that (149) of control mucosae. The populations of each isotype were also significantly increased over controls by factors of 1.6 (IgA; p less than 0.05), 3.0 (IgM; p less than 0.01) and 3.5 (IgG; p less than 0.01). Their percentage distributions in untreated coeliac mucosae (A:M:G--52:43:5) differed from those in control mucosae (A:M:G--69:28:3) but were restored after treatment with a gluten-free diet. However, when each isotype was expressed per unit volume of lamina propria, there was an apparent fall (X 1.4) in IgA cells, while the increase in IgM and IgG cells was less marked i.e. X 1.4 and X 1.5 respectively. These precise measurements explain why many previous investigators found a paradoxical fall in IgA cells because the (increased) volume of distribution of these cells was not taken into account. The importance of morphometric techniques in achieving valid cell 'counts' within the intestinal mucosa is thus illustrated by this study.

Celiac Disease↗
PubMed1985

Local immunodeficiency of the intestinal mucosa--a contribution to etiopathogenesis of recurrent urticaria and diarrhoea.

The case of a 10 month-old girl with a history of recurrent urticaria and diarrhoea is presented. Immunological study was carried out and secretory component in sputum, duodenal juice and stool was not found, while IgA was detected. Peroral biopsy of intestinum was also carried out and histology revealed partial villous atrophy. Immunofluorescent staining showed only a few IgA and IgG producing cells scattered within the villous stroma, while the IgM producing cells were increased in number. Serum concentration of IgA, IgM and particularly IgG was increased. Both parents had measurable IgA in the serum, however, the secretory component was not detectable neither in mother nor in father. The deficiency of secretory component and deficiency of IgA producing cells in the jejunal villous stroma led to local immunodeficiency of the intestinal mucosa and that caused recurrent urticaria and diarrhoea in the girl presented.

Antigen-Antibody Complex↗