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PubMed1991

Purification and characterization of phytase from rat intestinal mucosa.

Phytase (myo-inositol hexakisphosphate phosphohydrolase; EC 3.1.3.8 or 3.1.3.26) was purified from rat intestinal mucosa. The purified enzyme preparation exhibited two protein bands on SDS-polyacrylamide gel electrophoresis with estimated molecular masses of 70 kDa and 90 kDa. Rabbit antisera prepared against the 90K subunit cross-reacted with the 70K subunit on immunoblotting. The peptide maps of the 70K and 90K subunits were similar, and the N-terminal amino acid sequences of the two subunit proteins were almost identical. Treatments to remove sugar moieties from the proteins showed that the two subunit proteins had different oligosaccharide chains, although the difference in their molecular masses was not due to the difference in their oligosaccharide compositions. The purified enzyme also showed activity of alkaline phosphatase (orthophosphoric monoester phosphohydrolase; EC 3.1.3.1), but the properties of the two enzyme activities were different; the optimum pH for phytase activity was 7.5, while that for alkaline phosphatase was 10.4. Phytase activity did not necessarily require divalent cations, while Mg2+ was essential for alkaline phosphatase activity. Phenylalanine, a specific inhibitor of intestine-type alkaline phosphatase had no effect on the phytase activity.

6-Phytase↗
PubMed1979

The binding of zinc to the soluble proteins of intestinal mucosa in winter flounder (Pseudopleuronectes americanus).

1. The binding of Zn2+ to soluble proteins of intestinal mucosa of winter flounder was examined using an equilibrium dialysis technique. 2. There appeared to be more than one binding system present for Zn2+ in the mucosal cytosol. 3. It required four times the normal endogenous Zn2+ level found in the mucosal cytosol to saturate the highest affinity (K1 = 2.42 x 10(7] binding system. 4. Of 10 metals tested Cu2+ was the only one which interfered with Zn2+ binding to the mucosal cytosol proteins. 5. It is postulated that binding proteins in the mucosal cytosol of winter flounder may play a role in the transport of Zn2+.

Animals↗
PubMed1977

Coenzyme-A-dependent esterification of cholesterol in intestinal mucosa from guinea-pig. Influence of diet on the enzyme activity.

Guinea-pig intestinal mucosa contains a microsomal enzyme which catalyses the esterification of cholesterol. The enzyme is CoA-dependent and probably an acyl-CoA-cholesterol acyltransferase (ACAT) (E.C. 2.3.1.26). The apparent Km for the CoA in the combined enzyme reaction is 3.3 x 10(-5)M. The specific activity of cholesterol esterification is about five times higher in young suckling animals than in ordinary fed adult animals. Feeding fat and fat/cholesterol diets increases the activity two- to five-fold. Concomitantly the fat/cholesterol fed animals get a marked accumulation of free and esterified cholesterol in mucosal cells.

Acyltransferases↗
PubMed1988

Modulation of intestinal immune reactivity by interleukin 2. Phenotypic and functional analysis of lymphokine-activated killer cells from human intestinal mucosa.

There is evidence indicating that interleukin 2 may be important in the regulation of intestinal immunity, as suggested by its capacity to induce nonspecific cytotoxic (lymphokine-activated killer) activity from human intestinal mucosal mononuclear cells. The present study was designed to further explore the phenotypic and functional changes induced by interleukin 2 on intestinal lymphocytes derived from inflammatory bowel disease and control tissues. Immunohistology of intestinal mucosa demonstrated few cells bearing the activation antigen recognized by anti-Tac (anti-interleukin 2 receptor) monoclonal antibody. However, when isolated lamina proprial mononuclear cells were exposed to interleukin 2 in culture, the number of Tac-positive cells increased dramatically, a phenomenon paralleled by the generation of lymphokine-activated killer cell activity. This cytotoxic function was critically dependent on the continuous availability of interleukin 2, but not on the expression of the Tac antigen, since Tac-negative cells were also cytotoxic. Depletion of natural killer cells, fractionation into T cell-enriched and -depleted cells before and after culturing with interleukin 2, and separation into Tac-positive and -negative cells after interleukin 2 activation failed to eliminate lymphokine-activated killer cell activity, suggesting that this phenomenon is mediated by phenotypically and functionally heterogeneous cell subsets. During the induction of lymphokine-activated killer cells variable amounts of interferon-gamma were produced, but these did not correlate with the degree of cytotoxicity. No differences were observed between the response to interleukin 2 by inflammatory bowel disease and control cells. Therefore, in view of its capacity to induce significant phenotypic and functional changes in different subpopulations of intestinal mucosal mononuclear cells, interleukin 2 should be regarded as an important modulator of intestinal immune reactivity.

Adjuvants, Immunologic↗
PubMed2003

Ischemia of the intestinal mucosa during cardiopulmonary bypass.

Bacterial translocation is believed to occur during cardiopulmonary bypass (CPB) because serum endotoxin concentrations rise. Intestinal ischemia during CPB, however, has never been proven directly. The condition of the intestinal mucosa during CPB was studied by measuring serum diamine oxidase (DAO) activity, an index of intestinal ischemia. Serum DAO activity, blood lactate concentration, and the arterial ketone body ratio (AKBR) were measured intraoperatively in four successive patients who underwent aortic arch replacement by the open distal anastomosis method. DAO activity rose after restoration of blood flow to the lower half of the body, and continued to rise throughout CPB. The lactate concentration also rose, mirroring the change in DAO activity, and returned to nearly normal 12 h after the operation. The AKBR decreased during CPB, with a mean minimum vale of 0.16-0.07 immediately after the restoration of blood flow to the lower half of the body. The parallel rise in DAO activity and serum lactate concentration once blood flow to the lower half of the body was restored implies that ischemic injury to the mucosa of the small intestine occurs during CPB. The continued rise in these parameters throughout CPB is consistent with ongoing injury due to splanchnic hypoperfusion, as reflected in the decrease in the AKBR during the same period.

Aged↗
PubMed1995

Different organization of intermediate filaments in columnar cells of rat large intestinal mucosa as revealed by confocal laser scanning microscopy and quick-freezing and deep-etching method.

The relationship between cell differentiation and ultrastructural changes of intermediate filaments (IF) was studied in columnar cells of large intestinal mucosa of rats by confocal laser scanning microscopy and quick-freezing and deep-etching method. A feature of the IF in immature columnar cells was minibundle formation with prominent branching, which organized the meshwork structures. The minibundles, which appeared to be formed by the attachment of two or more IF in side-to-side fashion, were loosely distributed throughout the cytoplasm. In contrast, in mature columnar cells, the IF were densely distributed under the terminal web in the cytoplasm and beneath the upper part of the lateral membrane regions, whereas the other areas of the cytoplasm contained only a small number of IF. Minibundle formation was not observed, and the branching was rarely identified. The changes in the distribution and density of IF, which are expressed in specific areas of mature columnar cells, apparently represent a characteristic of intracellular differentiation. It is suggested that the dissociation of minibundled IF, which was often observed in the immature columnar cells, is an important step in the acquisition of functional polarity in cells of this type.

Animals↗
PubMed1989

Purification and characterization of proline-beta-naphthylamidase, a novel enzyme from pig intestinal mucosa.

An enzyme hydrolyzing proline-beta-naphthylamide was purified to apparent homogeneity from porcine intestinal mucosa. The purified enzyme appears to consist of three identical subunit polypeptides with a molecular weight of about 58,000 each, associated noncovalently. The enzyme is a glycoprotein, and the subunit polypeptide contains 3 residues each of mannose and N-acetylglucosamine. A wide variety of peptidase substrates were tested for the enzyme, and the results showed that it hydrolyzes only aminopeptidase substrates, such as proline-beta-naphthylamide, glycine-beta-naphthylamide, leucine-beta-naphthylamide, and alanine-beta-naphthylamide. Among these substrates, proline-beta-naphthylamide is most efficiently hydrolyzed as judged by the kcat/Km value. The optimum pH for this substrate is around 9. The enzyme also hydrolyzes efficiently the ester substrates of these amino acids. No hydrolytic activity was observed for the peptide and protein substrates tested. The proline-beta-naphthylamidase activity was drastically inhibited by diisopropylfluorophosphate, phenylmethanesulfonyl fluoride, and L-1-tosylamido-2-phenylethyl chloromethyl ketone, indicating that the enzyme is a serine hydrolase, whereas it was slightly inhibited by aminopeptidase inhibitors, such as amastatin, bestatin, and puromycin. No significant homology was found for the NH2-terminal sequence of 27 amino acid residues with any known protein sequences. From these results we conclude that the enzyme is a protein which has not been described before.

Amino Acids↗
PubMed1987

Binding of amino beta-lactam antibiotics to soluble protein from rat intestinal mucosa--I. Purification of drug-binding protein.

Several amino beta-lactam antibiotics, including ampicillin, amoxicillin, cyclacillin, cephalexin, cephradine and cefadroxil, were found to bind in vitro to specific components in 105,000 g supernatant of homogenate obtained from rat intestinal mucosa. The major binding component (fraction b) was purified by chromatography on DEAE-cellulofine and by gel filtration on Sephadex G-50. The molecular weight of fraction b was determined by SDS polyacrylamide gel electrophoresis (15,000 Da). The binding behaviour of these amino beta-lactam antibiotics to fraction b were estimated by equilibrium dialysis. There were significant high affinities of all tested amino beta-lactam antibiotics which were well absorbed from intestine, but there was not a good correlation between binding and absorption of these drugs. It was also found that poorly absorbed cephalosporins which lack aminobenzyl group in their structure, cefazolin and cephaloridine, did not bind to fraction b.

Animals↗
PubMed1979

Some characteristics of early appearing isomaltase in intestinal mucosa of suckling rat.

Characteristics of early appearing free isomaltase in the soluble fraction were investigated in rat intestinal mucosa. Soluble isomaltase and membrane-bound sucrase-isomaltase complex were prepared from 15-day-old rat intestine. Immunochemical properties, optimal pH and heat sensitivity of soluble isomaltase were compared with those of membrane-bound isomaltase. Optimal pH of free isomaltase in the soluble fraction was lower than that of membrane-bound isomaltase. Soluble and membrane-bound isomaltase showed different sensitivities for temperature. Furthermore, membrane-bound isomaltase in 15-day-old suckling rat intestine gave a single line with antiserum. However, soluble isomaltase gave no precipitin line. From these results, it could be concluded that soluble isomaltase is not derived from the isomaltase moiety of membrane-bound sucrase-isomaltase complex as a result of mechanical fragility and rather it would be lysosomal in origin.

Animals↗
PubMed1981

[Sodium 2,3-dithiopropanesulfate blockade of the effect of cholera enterotoxin on adenylate cyclase and the concentration of cyclic 3',5'-adenosine monophosphate in the small intestine mucosa of the rabbit].

Activation of adenylate cyclase in membrane preparations of the rabbit small intestine mucosa by cholera enterotoxin in the presence of sodium 2,3-dithiopropanesulfate (DTPS) is similar to that in the presence of dithiothreitol (DTT). Both DTT and DTPS do not influence the activity of adenylate cyclase without cholera enterotoxin. DTPS activates cyclic 3,5-AMP phosphodiesterase of mucosa homogenates (K0.5 = 10(-5) M). Combined administration of cholera enterotoxin and DTPS in situ into isolated loops of the rabbit small intestine decreases the activating effect of cholera enterotoxin on adenylate cyclase and diminishes the content of cyclic AMP in the mucosa. The destruction of disulfide bonds of cholera enterotoxin by DTPS is assumed to lower its ability to penetrate the mucosal cells of the small intestine.

Adenylyl Cyclases↗
PubMed1976

HCO-3-activated adenosine triphosphatase in intestinal mucosa of the eel.

An HCO-3-activated and SCN--inhibited ATPase (ATP phosphohydrolase, EC 3.6.1.3) found in homogenates of intestinal mucosa of the eel was solubilized by Triton X-100. Optimal HCO-3-concentration and pH for the enzyme were 25 mM and 8.7, respectively. HCO-3-ATPase activity in both homogenate and solubilized preparations increased after seawater adaptation. This adaptive increase in enzyme activity was also observed in the gills and the kidney. The HCO-3-ATPase seems to be related to transport mechanisms, especially for Cl-, in osmoregulatory surfaces of the eel.

Adenosine Triphosphatases↗
PubMedDate not supplied

Enzymological and morphological changes in rat intestinal mucosa following treatment with alkylating sugar alcohol derivatives.

Wistar rats were treated with alkylating sugar alcohol derivatives, dianhydrogalactitol (DAG) and diacetyldyanhydrogalactitol (Diac-DAG), respectively. The drugs were intravenously administered as a single, bolus injection. The applied doses 2.5, 5, 10, 17 mg/kg DAG and 5, 10, 20, 40 mg/kg Diac-DAG were roughly equitoxic. The effect of these cytostatic agents was studied on the different marker enzymes (thymidine kinase, xanthine oxidase, alkaline phosphatase, sucrase, maltase) of the separated mucosa cells derived from the functional and proliferating zone of the small intestine. Both DAG and Diac-DAG inhibited the enzyme activities of the proliferating and mature enterocytes in a dose dependent fashion, primarily acting on the crypt specific thymidine kinase. The time dependent sequence in the biochemical alterations correlated well with the cytomorphological changes. The drug-induced damage was most pronounced 48 hours after a single treatment. The regeneration of the intestinal mucosa began on days 3 and 4 and was completed by day 7. Diac-DAG at equimolar concentration proved to be more toxic than DAG on the intestine as judged by the significantly higher decrease of protein content and xanthine oxidase activity.

Animals↗
PubMed1993

Administration of different Lactobacillus strains in fermented oatmeal soup: in vivo colonization of human intestinal mucosa and effect on the indigenous flora.

In vivo colonization by different Lactobacillus strains on human intestinal mucosa of healthy volunteers was studied together with the effect of Lactobacillus administration on different groups of indigenous bacteria. A total of 19 test strains were administered in fermented oatmeal soup containing 5 x 10(6) CFU of each strain per ml by using a dose of 100 ml of soup per day for 10 days. Biopsies were taken from both the upper jejunum and the rectum 1 day before administration was started and 1 and 11 days after administration was terminated. The administration significantly increased the Lactobacillus counts on the jejunum mucosa, and high levels remained 11 days after administration was terminated. The levels of streptococci increased by 10- to 100-fold in two persons, and the levels of sulfite-reducing clostridia in the jejunum decreased by 10- to 100-fold in three of the volunteers 1 day after administration was terminated. In recta, the anaerobic bacterium counts and the gram-negative anaerobic bacterium counts decreased significantly by the end of administration. Furthermore, a decrease in the number of members of the Enterobacteriaceae by 1,000-fold was observed on the rectal mucosa of two persons. Randomly picked Lactobacillus isolates were identified phenotypically by API 50CH tests and genotypically by the plasmid profiles of strains and by restriction endonuclease analysis of chromosomal DNAs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Somatostatin content and binding in small intestinal mucosa from fed, fasted, and refed rabbits.

The present study is an investigation of the effects of 12- to 96-hours' starvation and 96-hours' starvation plus 48-hours' refeeding on both somatostatin-like immunoreactivity (SLI) and cytosolic somatostatin binding sites in rabbit small intestinal mucosa. The SLI concentration increased after 24 h in duodenal and jejunal mucosa, but not in ileal mucosa, and reached its highest value after 96 h of fasting. The number of specific high and low-affinity somatostatin binding sites, but not their affinity, decreased with the duration of fasting in the same gut segments, refeeding of fasted animals resulted in a return to normal control values for small intestine mucosal SLI and somatostatin binding.

Animals↗
PubMedDate not supplied

Vagal afferent nerve fibres contact mast cells in rat small intestinal mucosa.

Mast cells degranulate when exposed to specific antigens (via surface bound IgE), resulting in the release of numerous pro-inflammatory mediators. Neuroregulatory substances also activate mast cells, and may effect differential mediator release, without degranulation, suggesting a role for nerves in modulating mast cell activity. We previously investigated the microanatomical relationships of intestinal mucosal mast cells (IMMC) with nerves and found extensive associations in the intestinal mucosae of rats and humans. The origins of nerves that contact IMMC have not been determined; however, recent morphological and functional studies suggest the possibility that the vagus nerve might be involved. In the current study we show that vagal afferent fibers (labeled by injecting DiI into the nodose ganglion) penetrate to the tips of jejunal villi; and that some of these nerves make intimate contact with IMMC. These data provide the microanatomical basis for direct neural communication between the central nervous system (CNS) and mast cells in the gastrointestinal mucosa.

Afferent Pathways↗
PubMed1989

Chemical modification and composition of tetrameric isozyme K of alkaline phosphatase from harp seal intestinal mucosa.

1. The carbohydrate content of isozyme K of alkaline phosphatase (EC 3.1.3.1) from harp seal intestinal mucosa was examined. The presence of N-acetylglucosamine, N-acetylgalactosamine and considerable amounts of mannose residues was shown. 2. The amino acid content of seal alkaline phosphatase was determined. A high extent of homology (85%) between bovine and seal alkaline phosphatases was demonstrated. 3. By chemical modification lysine, dicarboxylic acids, arginine and tyrosine residues of tetrameric seal alkaline phosphatase are located near or at the active site. By contrast, the modification of either thiol or imidazole groups resulted in no alterations of the enzyme activity. 4. It has been demonstrated that inorganic phosphate is an inhibitor of alkaline phosphatase and entirely prevents the enzyme inactivation with succinic anhydride.

Alkaline Phosphatase↗