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PubMed1980

Transepithelial fluxes of amino acids and metabolism in the tortoise intestinal mucosa.

Transepithelial fluxes of six amino acids (Ala, Leu, Ser, Lys, Glu, Cyclo) across the tortoise intestinal mucosa are studied. The fraction of these amino acids which is metabolized in the cells and appear in the bathing solutions is estimated. Incorporation of labelled amino acids into macromolecules is also detected. Results are suggestive that an amino acid moving from mucosa to serosa takes a different route from that moving in the opposite direction. Comparison with results obtained in mammalian intestinal mucosa is discussed.

Amino Acids↗

PubMed1990

[Absorption disorders following gastric resection--morphological and enzyme-histochemical observations on the small intestinal mucosa].

For the purpose of studying digestion and absorption disorders following stomach surgery, particularly with respect to membrane digestive functional disorders, morphological and enzyme-histochemical observation of the small intestinal mucosa was performed, and a comparison was done between the partial gastrectomy group (59 cases), and the total gastrectomy group (52 cases). The following results were obtained: 1) The small intestinal mucosa showed a tendency to significant villous atrophy in post-operative groups. 2) There was a significant decrease in the disaccharidase activity, especially in the small intestine of the total gastrectomy group. ALP, LAP and gamma-GPT activity also decreased, or disappeared in the small intestines showing villous atrophy. 3) In the atrophied mucosa which showed a marked decrease in membraneous enzyme activity, poorly-formed, irregularly sized microvilli accompanied by glycocalyx irregularity and disappearance were recognized under the electron microscope. The above mentioned morphological and enzyme-histological findings in the small intestinal mucosa, were strongly reflected in both post-operative progress and clinical symptoms.

Atrophy↗

PubMed1990

Postirradiation changes in small intestine mucosa of piglets selectively decontaminated by peroral antibiotics.

There was performed light microscopic and morphometric comparison of changes in the intestinal mucosa structure after the irradiation of the lower part of body by radiation 60Co in a dose of 12 Gy, observed the third day after irradiation in piglets kept under conventional conditions and the fifth, the fifteenth and the twentieth days after irradiation in piglets kept under the conditions of selective decontamination by peroral antibiotics. The non-irradiated animals kept conventionally as well as under the conditions of decontamination served as controls. The estimation was performed on transverse slices of the cranial part of jejunum and of the caudal part of ileum. The slices were stained by the method hematoxylin-eosin. The drawings prepared with the help of the projective microscope Pictoval were used for measuring on the apparatus for the quantitative analysis of image MOP AM 03. A markedly lower damage of the intestinal mucosa was evidenced in piglets selectively decontaminated by peroral antibiotics. In the studied time intervals after irradiation in a dose of 12 Gy, the epithelial cover of mucosa, the crypt epithelium and the general outline of mucosa are much better maintained. The favourable effect of the selective decontamination on the maintenance and regeneration of the mucosa of jejunum and ileum is confirmed by a range of morphometric parameters.

Administration, Oral↗

PubMed2003

Glucagon-like peptide-2 receptor activation in the rat intestinal mucosa.

Glucagon-like peptide-2 (GLP-2) increases small intestinal growth and function in rodents and human subjects. GLP-2 exerts its effects through a seven-transmembrane domain, G protein-coupled receptor (GLP-2R), stimulating cAMP generation and activating protein kinase A signaling in heterologous cell lines transfected with the GLP-2R. As intestinal cell lines expressing the GLP-2R have not been identified, we developed methods for studying GLP-2R signaling in the rat small intestinal mucosa in vitro. Isolated rat intestinal mucosal cells expressed mRNA transcripts for the GLP-2R, as well as for chromogranin A and beta-tubulin III, markers for enteroendocrine and neural cells, respectively. cAMP production in response to [Gly2]GLP-2, a degradation-resistant analog of GLP-2, was maximal at 10-11 m (268 +/- 93% of control, P < 0.001), with reduced cAMP accumulation observed at higher doses. The cAMP response was diminished by pretreatment with 10-9 m GLP-2, and was abolished by pretreatment with 10-6 m GLP-2 (P < 0.05), indicating receptor desensitization. GLP-2 treatment of isolated mucosal cells increased 3H-thymidine incorporation (to 128 +/- 8% of controls, P < 0.05), and this was prevented by inhibition of the protein kinase A pathway with H89. In contrast, GLP-2 did not affect p44/p42 MAPK phosphorylation or the levels of cytosolic calcium in the mucosal cell preparation. These results provide the first evidence that activation of the endogenous rat mucosal GLP-2 receptor is linked to activation of a cAMP/protein kinase A-dependent, growth-promoting pathway in vitro.

Animals↗

PubMed2005

[Dynamic observation of pathological changes and expression of nuclear factor-kappaB in the intestinal mucosa of rats after diffuse brain injury].

OBJECTIVE: To investigate the dynamic pathological changes in the intestinal mucosa of rats and the role of activation of nuclear factor-kappaB (NF-kappaB) in the alteration in intestinal mucosal barrier dysfunction after diffuse brain injury. METHODS: The animal model established by Marmarou was used to produce diffuse brain injury. One hundred and fifty male Wistar rats were randomly divided into nine groups in terms of postinjury time: 1, 2, 4, 8, 12, 24, 48, 72, 168 hours after injury, and control group. Mucosal thickness, villous height and width were estimated under light microscope, and expression of NF-kappaB was assessed with immunohistochemical staining in control group to compare with those in injury groups. RESULTS: Mucosal thickness, villous height and width were diminished and the optical density of expression of NF-kappaB was much higher in the injury groups than those of control group. CONCLUSION: The structure of intestinal mucosa is damaged in the earlier stages after diffuse brain injury. NF-kappaB is activated by cellular stress, which may be involved in the pathogenesis of secondary intestinal lesion.

Animals↗

PubMed1982

[Antigenic cross-reaction between neonatal intestinal mucosa and certain serotypes of Escherichia coli].

In the soluble and insoluble fractions of three intestinal mucosa of neonates, a study was made of the contents of Kunin's (ECA) common heterogenous antigen, and of somatic antigens of different E. coli serotypes. In the three mucosas, evidence was found that a fraction capable of hindering the antiserum anti-014, (antiserum anti-ECA), does exist. It was also discovered that the three mucosas have a variable content of substances which hinder antiserums contrary to different somatic antigens of various E coli's serotypes. Furthermore, the soluble and insoluble fractions of the intestinal mucosas "combine' when they are preincubated with some of the crude lipopolysaccharides (LPS) of E. coli enteropathogens and non-enteropathogenes, according to the determining antigens be they divided into equal parts or not. This last phenomenon modifies, in variable degrees, the capacity of these fractions to hinder the antiserums contrary to the determinative equal parts with E. coli. Based on the above observations, the author proposes a hypothesis in order to explain the different behaviour, (pathogen and/or commensal), of a similar E. coli's serotype when it settles in the intestine of different people

Antigens, Bacterial↗

PubMed1986

All-trans-retinoic acid inhibits retinol esterification by acyl-CoA: retinol acyltransferase (EC 2.3.1.76) from rat and human small intestinal mucosa.

1. Formation of retinyl esters catalyzed by acyl-CoA:retinol acyltransferase (ARAT; retinol fatty-acyltransferase; EC 2.3.1.76) from intestinal mucosa has been studied in vitro in the presence of all-trans-retinoic acid. 2. The incubation system contained microsomal preparations from the tissue tested, radioactive retinol and palmitoyl-CoA. The product formed was separated from the substrates by chromatography on alumina columns. 3. All-trans-retinoic acid inhibited ARAT both from rat and human intestinal mucosa. 4. Inhibition occurred instantly. At a concentration of retinol of 80 microM, a 50% inhibition was obtained with 50 microM-retinoic acid. 5. The inhibition of ARAT by retinoic acid may be of importance for normal retinol absorption in patients receiving retinoid therapy.

Acyltransferases↗

PubMedDate not supplied

[Digital morphometric and stereologic analysis of small intestinal mucosa in well-nourished and malnourished children with persistent diarrhea].

OBJECTIVE: To test the hypothesis that the proximal small intestines of children with persistent diarrhea present morphometric and stereologic changes proportional to their nutritional status, using microscope images stored in a computer. METHODS: Cross-sectional study with 65 pediatric patients, whose ages ranged from 4 months to 5 years, with persistent diarrhea for over 14 days. The nutritional assessment was performed according to the z-scores for weight/age (W/A), weight/height (W/H) and height/age (H/A) ratios, divided into: well-nourished = z > or =2SD and malnourished = z<2SD; well-nourished = z > or =2SD, nutritional risk = z<1SD and malnourished = z<-2SD; and continuously, in descending order, using the NCHS charts. After obtaining the computer images using the software Scion Image, villous height, crypt depth, mucosal thickness, total mucosal thickness, and villous/crypt ratio were measured in the fragments of the small intestinal mucosa, enlarged 100 times. When images were enlarged 500 times, enterocyte height, nuclear height and brush-border height were measured. Stereologic analysis was performed using cycloid arcs. RESULTS: For W/A, W/H and H/A z-scores, divided into two nutritional status categories, no statistically significant difference was observed in regard to villous height, crypt depth, mucosal thickness, total mucosal thickness and villous/crypt ratio. Enterocyte height presented the most significant difference between well-nourished and malnourished groups, for W/A and W/H ratios, with a 500x enlargement, although this difference was not statistically significant. When z-scores were subdivided into three nutritional status categories, a digital morphometric analysis showed a statistically significant difference for villous/crypt ratio between the well-nourished and slightly malnourished group and the well-nourished and mild to severe malnourished group (p=0.048). The villous/crypt ratio was higher among well-nourished children. Using the Spearman coefficient, the variables enterocyte height, height of enterocyte nucleus and brush-border height presented a clear association with the W/A ratio (r=0.25; p=0.038), W/H ratio (r=0.029; p=0.019). The height of the enterocyte and the brush-border height were associated with W/H ratio. CONCLUSION: The observed associations between nutritional status and the analyzed small intestinal mucosa variables showed a positive correlation with patients' weight. Although these associations were of a slight to moderate magnitude, we observed a tendency of enterocyte size reduction, as well as a reduction in the size of its nucleus and brush-border, as the level of malnutrition increases.

Body Weight↗

PubMed1988

Pyruvate carboxylase, phosphate-dependent glutaminase and glutamate dehydrogenase in the developing rat small intestinal mucosa.

The activities of glutaminase and glutamate dehydrogenase in the small intestinal mucosa of infant rats were found to increase at the time of weaning. Pyruvate carboxylase activity, on the other hand, was very high during the suckling period and decreased to negligible values at weaning. It is suggested that gluconeogenesis in the infant mucosa occurs primarily via oxaloacetate and not via alpha-ketoglutarate.

Aging↗

PubMed1983

Pyrroline-5-carboxylate synthesis from glutamate by rat intestinal mucosa. Subcellular localization and temperature stability.

The demonstration of the ornithine biosynthesis from glutamate in cell-free homogenates of rat intestinal mucosa by Ross, G., Dunn, D., and Jones, M.E. (1978) Biochem. Biophys. Res. Commun. 85, 140-147 suggested that this tissue might have the capacity to convert glutamate to pyrroline-5-carboxylate (P5C). We have shown in the preceding paper (Wakabayashi, Y., and Jones, M.E. (1983) J. Biol. Chem. 258, 3865-3872) that this is the case. The intracellular distribution of the P5C-synthesizing activity was investigated utilizing a newly developed procedure for subcellular fractionation of the rat intestinal mucosa. We found that the activity resided in the mitochondrial fraction as characterized by marker enzymes and an electron micrograph. The mitochondrial membrane fraction, freed of the soluble matrix and intermembrane space enzymes, retained all of the P5C-synthesizing activity. Addition of the soluble fraction to the membrane fraction did not affect the activity. P5C synthase, the name we have chosen for the protein(s) that catalyzes P5C synthesis from glutamate when ATP and NADPH are present, is susceptible to thermal inactivation in the presence of detergent. By lowering the incubation temperature to or below 20 degrees C, one can obtain a linear production of P5C with respect to time and protein concentration. Lower incubation temperatures are recommended for routine assay of this enzyme(s). Addition of 30% glycerol to the incubation mixture resulted in a linear formation of P5C with time at 30 degrees C; this and other data suggest that polyhydroxylic compounds may protect this protein against denaturation. Preliminary experiments suggest that P5C synthase can be extracted from a mitochondrial membrane in the presence of detergent, a high salt concentration, and glycerol. The possibility that the enzyme(s) is located in the inner mitochondrial membrane is discussed.

Animals↗

PubMed2003

Demonstration of functional role of TECK/CCL25 in T lymphocyte-endothelium interaction in inflamed and uninflamed intestinal mucosa.

It has recently been suggested that C-C chemokines may play a role in the organ-specific homing of lymphocytes, but there is not enough in vivo evidence in intestinal mucosa. The aim of this study was to examine whether thymus-expressed chemokine (TECK)/CCL25 and its ligand CCR9 are involved in T-lymphocyte interaction with microvessels of murine intestinal mucosa. T lymphocytes from the small intestine were fluorescence labeled, and their adhesion to mucosal microvessels was observed by intravital microscopy. Lamina proprial lymphocytes (LPL) and intraepithelial lymphocytes (IEL) adhered to both the small intestine and colon, and desensitization of CCR9 with TECK/CCL25 or anti-TECK/CCL25 antibody significantly inhibited these adhesions only in small intestine. At both sites, TNF-alpha significantly increased LPL adhesion but not IEL adhesion. Desensitization of CCR9 or anti-TECK/CCL25 antibody also attenuated the TNF-alpha-induced LPL adhesion in the small intestine. Increased expression of TECK/CCL25 by TNF-alpha was observed in the lamina propria of small intestine. TECK/CCL25 may thus play an important role in the adherence of mucosal lymphocytes to the microvessels of the small intestine but not the colon under uninflamed as well as inflamed conditions.

Animals↗

PubMed1998

Nutrients regulate diamine oxidase release from intestinal mucosa.

Diamine oxidase is continuously released from the intestinal mucosa and carried to the circulation by the lymphatics. The effect of nutrients on this release was examined. Rats were prepared with duodenal and intestinal lymph cannulas. Test mixtures of lipid emulsions containing triolein, oleic acid, or tricaprylin and solutions of carbohydrate and protein were infused into the duodenum. The enzyme release and triglyceride transport were determined and in some experiments were done in the presence and absence of Pluronic L-81, an inhibitor of chylomicron formation, and aminoguanidine, an inhibitor of diamine oxidase activity. The data indicate that nonlipid nutrients did not increase diamine oxidase activity in the intestinal lymph, but the mucosal tissue content was significantly reduced in the distal small intestine, particularly after protein infusion. Triglycerides and fatty acids increased diamine oxidase in the intestinal lymph, and the longer-chain triglyceride was more effective. Inhibition of triglyceride transport did not interfere with the enzyme release, and the inhibition of diamine oxidase activity had no significant effect on lipid absorption. According to our observations, only lipids increase intestinal lymph diamine oxidase. Nonfat nutrients appear to increase diamine oxidase in the intestinal lumen. Diamine oxidase is not directly required for lipid absorption.

Amine Oxidase (Copper-Containing)↗

PubMed1990

Purification, properties, and function of flavokinase from rat intestinal mucosa.

Flavokinase (ATP:riboflavin 5'-phosphotransferase) [EC 2.7.1.26] was purified to apparent homogeneity from rat intestinal mucosa by fractionation with ammonium sulfate, gel filtration, and flavin affinity chromatography. The addition of ATP to the enzyme solution was necessary for its binding to the affinity gel. The apparent molecular weight of the enzyme was estimated to be 13,500 by gel filtration on Sephadex G-100 and by SDS-PAGE. The properties of the enzyme, including its flavin specificity, were studied. Three types of riboflavin analogues were used for the flavin specificity study; namely, ones modified at the ribityl group, and at positions 3 and 8 of the isoalloxazine ring. Of the analogues modified at the ribityl group or position 3 of the isoalloxazine ring, only 2'-deoxyriboflavin was phosphorylated and then only weakly. On the other hand, most analogues modified at position 8 of the isoalloxazine ring were good substrates for the kinase, an appropriate increase in the substituent volume at position 8 of the isoalloxazine ring resulting in an increase in the Vmax value. In a previous paper on the mechanism of intestinal absorption of riboflavin, we proposed that one of the specific processes for the absorption of riboflavin is phosphorylation by flavokinase [Kasai, S. et al. (1988) J. Nutr. Sci. Vitaminol. 34, 265-280]. The present results support this conclusion because analogues that were absorbed at low concentrations through a process specific for riboflavin in our previous study were phosphorylated effectively by the enzyme, whereas those that were absorbed solely through simple diffusion at all concentrations were not phosphorylated or only phosphorylated weakly. The properties of the flavokinases from intestinal mucosa and liver were compared.

Animals↗

PubMed1976

Studies on translocation of immunoglobulins across intestinal epithelium. II. Immunoelectron-microscopic localization of immunoglobulins and secretory component in human intestinal mucosa.

To define mechanisms involved in the transport of immunoglobulins into intestinal fluids, we localized IgM, IgA, IgG, and secretory component (SC) in human intestinal mucosa by the peroxidase-labeled antibody technique. At the light microscopic level, immunocytes containing IgA, IgM, or IgG were found in the lamina propria. IgA, IgM, and SC were prominent in the epithelium of gland crypts; IgG was limited to a few cells at tips of villi. At the electron-microscopic level, SC was localized to perinuclear spaces, endoplasmic reticulum, saccules associated with Golgi complexes, cytoplasmic vesicles, and lateral and basal plasma membranes of columnar epithelial cells. IgA and IgM, but not IgG, also were localized to plasma membranes and cytoplasmic vesicles of these cells. Neither the immunoglobulins nor SC was found within other types of epithelial cells (Paneth, goblet, endocrine). The findings provide evidence that (1) the site of SC synthesis in intestinal epithelium is secretory columnar cells, principally those in gland crypts; (2) the polymeric immunoglobulins IgM and IgA are translocated through such SC-containing cells by a process that involves formation of cytoplasmic vesicles; (3) IgM and IgA could combine with SC during transcellular transport (likely sites are lateral or basal plasma membranes or supranuclear cytoplasm); (4) the monomeric immunoglobulin IgG does not share the transepithelial cell route involved in IgM and IgA transport.

Biological Transport↗

PubMed1986

The dependence of the rate of BP metabolism in the rat small intestinal mucosa on the composition of the dietary fat.

We studied the effects that dietary fat has on the capacity of preparations of rat small intestinal mucosal cells to metabolize benzo[a]pyrene (BP) in vitro and on the composition of fatty acids in the endoplasmic reticulum of the intestinal mucosa. When rats were fed diets containing different types of fat, there were significant changes in the incorporation of fatty acids into the endoplasmic reticulum of the mucosal cells of the small intestine: the proportions of polyunsaturated fatty acids in the endoplasmic reticulum reflected the amounts of these fatty acids in the dietary fat. The rate of BP oxidation in the intestinal mucosa was dependent on the amount and composition of the dietary fat, but the range and proportions of the metabolites produced were not affected. Dietary C18:2 was particularly important in elevating the rate of BP oxidation, but dietary C20:5 and C22:6 also effectively increased the rate of BP oxidation. The rate of BP oxidation in the small intestine of rats fed different diets was positively correlated with the proportion of polyunsaturated fatty acids in the endoplasmic reticulum of the mucosal cells.

Animals↗

PubMed1991

[Histochemistry of acid phosphatase in small intestine mucosa in experimental coccidiosis in suckling piglets].

The activity of acid phosphatase (phosphohydrolase of orthophosphate monoesters; EC. 3.1.3.2) was evaluated densitometrically in the mucosa of duodenum, jejunum and ileum of 22 conventional piglets which were experimentally infected by oocysts of the coccidiae Isospora suis (infection dose of 200,000 oocysts) on day one after parturition (DAP). The activity of the studied hydrolase was investigated in the infected piglets during days two to ten after infection (DAI) in the intestinal mucosa (enterocytes) and in goblet cells. The density of the reaction product of acid phosphatase was simultaneously determined in the same mucosal cells of different sections of the small intestine in five control conventional piglets at the age of 2-14 days. In the small intestine mucosa of control piglets the activity of acid phosphatase was demonstrated to be located especially in the supranuclear zone of enterocytes. As for goblet cells, the reaction product of acid phosphatase is distributed in all zones (supra-, para-, infranuclear zones); the lowest density of this enzyme was found in the infranuclear zone. The activity of acid phosphatase is also localized in intestinal crypts: in their cells the enzyme concentration is decreasing from duodenum to caudal sections. Important changes were revealed, in comparison with the control data, in the development of the activity of acid phosphatase in the intestinal mucosa cells in the experimentally infected piglets. In the period of investigation (DAI 2-10) there were two stages of the development of the density of the enzyme reaction product. The first stage can be characterized by an increase, the other by a decrease in the level of acid phosphatase activity. Enterocytes are influenced in both stages, but the decrease in the density of the reaction product of acid phosphatase was observed only in absorption cells, and not in goblet cells. The increase in the activity of acid phosphatase occurs in the periods of DAI 4 and 9-10. Enzymatic deviations occur mainly in the absorption cells of the mucosa of duodenum and middle jejunum; in the cells of posterior jejunum and ileum an increase in the density of the reaction product of acid phosphatase was also demonstrated, but at the lower quantitative level (especially on DAI 4). The decrease in the activity of acid phosphatase has a protracted development and it takes place on DAI 5 to 8.(ABSTRACT TRUNCATED AT 400 WORDS)

Acid Phosphatase↗

PubMed2000

Permeability of intestinal mucosa from urinary reservoirs in man and rat.

OBJECTIVE: To evaluate the barrier properties of intestinal mucosa chronically exposed to urine and to evaluate possible differences between ileal and colonic segments used in the reconstruction of the urinary tract. MATERIALS AND METHODS: Mucosal specimens from patients with continent reservoirs with an abdominal stoma, or orthotopic neobladders constructed from colonic segments, were obtained at revisional surgery. Control segments were obtained during right-sided hemicolectomy. In addition, ileal and colonic segments from enterocystoplasties in rats were assessed. The mucosa-to-serosa passage of marker molecules, i.e. (14)C-mannitol, (3)H-glucose, fluorescein isothiocyanate-dextran 4400 and ovalbumin, was measured using modified Ussing diffusion chambers. RESULTS: In man, there were no permeability differences between segments exposed to urine and control segments for any of the marker molecules. In rats, there was less passage of markers in ileal and colonic transplanted segments than in intestinal segments from sham-operated animals. CONCLUSIONS: Intestinal mucosa that has been in chronic contact with urine maintains its barrier function; in the rat model the permeability was even decreased. In addition, there were no detectable differences between ileal and colonic segments in this model.

Adult↗

PubMed1984

Surface ultrastructure of the small intestine mucosa in healthy children and adults: a scanning electron microscopic study with some methodological aspects.

Biopsy specimens of light microscopically (LM) normal small intestine mucosa from eight healthy, constitutionally short-statured children without signs of gastrointestinal disease and six healthy adults were studied by scanning electron microscopy (SEM) supplemented by transmission electron microscopy (TEM). The effects on surface morphology of various preparative procedures were also investigated, using small intestine mucosa from cats and rats. Fixation with OsO4--either alone, or following glutaraldehyde fixation--markedly changed the surface ultrastructure compared to that after glutaraldehyde fixation only. By low power SEM, some differences were observed in the appearance of the small gut mucosa between adults and young children. In adults and in children above 3 years of age, the villi were usually shaped like fingers or leaves, but in infants, ridge-shaped villi predominated. The villi showed, however, a smooth surface in both infants and adults, and medium and high power SEM displayed similar pictures, irrespective of age; here the typical structural features of the normal small gut mucosa in humans were (1) distinct extrusion zones at the crests of the villi and almost no signs of enterocyte extrusion along the sides of the villi, and (2) regular enterocytes with polygonal, flat, apical surfaces covered by a thick glycocalyx that obscured the underlying microvilli.

Adolescent↗