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At least 811 records · Page 45Linked to original sources

PubMed1997

The hog intestinal mucosa acylase I: subcellular localization, isolation, kinetic studies and biological function.

The soluble acylase I (N-acylamino acid amidohydrolase, EC 3.5.1.14) from hog intestinal mucosa was 11,000-fold purified for the first time using a new four-step procedure involving an immunoaffinity chromatography. The resulting protein, which had an isoelectric point of 5.2 and a M(r) of 90,000 was composed of two apparently identical N-acylated polypeptide chains. Its amino acid composition was comparable to that of hog kidney acylase I. The enzyme had a pH optimum at 8.0 and required Zn2+ or Co2+. The optimal temperature for the acylase reaction was 40 degrees C and the activation energy of thermodenaturation was estimated at 260 kJ mol-1. The enzyme was strongly inhibited when preincubated with chelating agents, by diethyl pyrocarbonate under histidine-modifying conditions as well as by sulfhydryl compounds. The reaction of the purified enzyme with the synthetic substrate furylacryloyl-L-methionine was partly characterized as follows: Km = 0.22 +/- 0.03 mM, kcat = 128.0 +/- 17.8 s-1 and kcat/Km = 5.8 +/- 1.6 x 10(5) M-1 s-1. The L-stereoisomer of methionine competitively inhibited the enzyme reaction with a Ki of 3.4 +/- 0.2 mM. It is suggested that acylase I might not only be involved in the catabolism of intracellular N-acylated protein but also be responsible for the biological utilization of N-acylated food proteins.

Amidohydrolases↗

PubMed1983

Nature of interaction of different wild type Vibrio cholerae with intestinal mucosa.

Scanning electron microscopy (SEM) was used in this study to investigate the mechanism of association of cholera vibrios with the intestinal mucosa. For this purpose, the interactions of three virulent, wild type strains (CA401, P, and 3083) of Vibrio cholerae with intestinal segments of infant mice were compared. The results of previous studies by different investigators using the three strains separately and in different assay systems had led to differing conclusions concerning the mechanisms of association with the mucosa. In this study, observations by SEM of the infant mouse intestinal segments, previously incubated in suspensions of the organisms, revealed that all three strains preferentially associated with intestinal mucin. The vibrios associated poorly with the mucosal epithelial surface even in areas of the segments free of mucin or in segments washed to remove mucin prior to the assay. In each case, the vibrios associated better with the serosal surface than with the epithelial surface of the mucosa, but not to the degree that they associated with mucin on the mucosal surface. The major difference observed by SEM of the strains was the markedly greater association of strain 3083 with the serosal surface as compared to strains CA401 and P.

Animals↗

PubMed1977

Lymphoid cells of the normal man intestinal mucosa possessing both kappa and lambda light chain specifities.

The presence of lymphoid cells possessing both kappa and lambda specificities has been observed in the intestinal mucosa of normal subjects. The variability in the number of such cells in different sections of the same sample and in different subjects seems to be a characteristic of this cell population and may reflect the high activity of the immune system in the gut.

Antibody-Producing Cells↗

PubMed1987

Enzymatic oxidation of bilirubin by intestinal mucosa.

Bilirubin oxidase, an aerobic enzyme which degrades bilirubin 'in vitro' to colourless diazo-negative compounds, including propentdyopents and trace amounts of biliverdin, has been demonstrated in homogenates of rat intestine, kidney and liver. The enzyme in the intestinal mucosa has been partially characterised and appears to be mitochondrial in origin; maximal activity was detected in the jejunum. Intestinal bilirubin oxidase has a mean activity of 0.51 +/- 0.03 (S.D.) nmol bilirubin degraded/min per mg protein. Similar bilirubin oxidase activities were found in the tissue of Sprague-Dawley and Gunn rats. The role of the enzyme 'in vivo' remains to be determined.

Animals↗

PubMed1995

Dietary effects of faba-bean (Vicia faba L.) tannins on the morphology and function of the small-intestinal mucosa of weaned pigs.

The objective of the present study was to evaluate effects of condensed tannins in faba beans (Vicia faba L.) on morphological and functional variables of the small-intestinal mucosa of piglets. In an experiment with young piglets (8-17 kg body weight), fed on either a control diet or a diet containing 200 g/kg of low- or high-tannin faba bean hulls (with < 0.10 and 3.3% catechin equivalents of condensed tannins respectively), morphological and functional characteristics of the jejunal mucosa were determined. Results of the study showed that the morphological variables of the mucosa of the three groups of piglets were similar. Also, no changes due to dietary tannins were observed in sucrase (EC3.2.1.48)-isomaltase (EC 3.2.1.10) activity in homogenates of mucosa plus submucosa. However, aminopeptidase (EC 3.4.11.2) activity in these homogenates in the proximal part of the small intestine of the animals of the group fed on the high-tannin diet was significantly lower than that in the animals fed on the control diet or the diet with low-tannin hulls (P < 0.05).

Aminopeptidases↗

PubMed1983

Separation of two forms of cytochrome P-450 with aryl hydrocarbon hydroxylase activity from intestinal mucosa microsomes of rabbits treated with 3-methylcholanthrene.

Two forms of cytochrome P-450, designated P-448a and P-448b, were purified from intestinal mucosa microsomes of rabbits treated with 3-methylcholanthrene. Both the cytochromes had absorption maxima at 448 nm in the carbon monoxide-reduced difference spectra. They exhibited comparable catalytic activities with benzo(a)pyrene, 7-ethoxycoumarin, and 7-ethoxyresorufin, when reconstituted with hepatic NADPH-cytochrome c reductase and phosphatidylserine. P-448a was apparently homogeneous on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and its monomeric molecular weight was estimated to be 58,000. The oxidized form had absorption maxima at 416, 512 and 571 nm, indicative of the low spin state. Thus P-448a appeared to be similar to one form of P-450, which was induced in rabbit liver by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). On the other hand, SDS-PAGE of P-448b gave a single major protein band with a monomeric molecular weight of 55,500, indicating that P-448b can be distinguished from P-448a.

Animals↗

PubMed1998

HIV-1 p24 but not proviral load is increased in the intestinal mucosa compared with the peripheral blood in HIV-infected patients.

OBJECTIVE: To investigate differences in viral and proviral load between the peripheral blood and the intestinal mucosal immune system in HIV-infected patients. DESIGN: HIV-1 p24 and HIV DNA content were compared in blood samples and intestinal biopsies from HIV-infected patients. METHODS: Intestinal biopsies and peripheral blood were simultaneously obtained from 27 HIV-infected patients undergoing diagnostic endoscopy. The p24 concentrations were measured in serum and homogenized intestinal biopsies by enzyme-linked immunosorbent assay after acid-dissociation of immune complexes. Proviral load was determined in blood and intestinal biopsies by a quantitative competitive polymerase chain reaction amplifying the HIV-1 nef gene from genomic DNA. RESULTS: No significant differences were found in proviral load comparing HIV copies per 1.5 x 10(5) cell equivalents in blood [2650 (600-44000)] and intestinal biopsies [4200 (1325-19 625)]. Paired analysis revealed a strong positive correlation between serum and mucosal proviral load. In contrast, HIV core protein p24 was detected in intestinal biopsies from 18 patients in much higher concentrations than in serum [858 (262-4111) pg/g versus 34 (9-242) pg/g; P < 0.005]. The p24 concentrations in serum and intestinal biopsies did not correlate and no significant correlation was observed in serum or intestinal biopsies between proviral load and p24 concentrations. No clear correlations were observed between clinical parameters and HIV DNA or HIV p24 levels in blood or biopsies. CONCLUSIONS: Our findings demonstrate a homogenous distribution of HIV proviral load in the peripheral blood and the intestinal mucosal immune system. The high viral antigen load in the intestine therefore indicates that mucosal HIV production is upregulated at the transcriptional and/or translational level. The intestinal mucosa is a major reservoir for HIV in HIV-infected patients.

Adult↗

PubMed2006

Pycnogenol protects against Ionizing radiation as shown in the intestinal mucosa of rats exposed to X-rays.

X-rays and gamma radiation delivered to the abdominal region for cancer treatment encompasses severe damage to the intestinal mucosa, which significantly impairs a patient's quality of life. To a great extent the deleterious effects of x-radiation originate from radiolysis-induced reactive oxygen species. The well-researched powerful antioxidant Pycnogenol was administered orally to rats prior to x-irradiation with 15 Gy. Histological sections of the intestines showed a dramatically better condition of the mucosal layers compared with the irradiated control animals administered water without Pycnogenol. Pycnogenol treatment significantly preserved the height and number of villi as well as the glandular layer and a diminished number of congested vases were present. No intestinal alterations were seen in control animals receiving Pycnogenol in the absence of radiation. It is concluded that Pycnogenol provides significant protection from ionizing radiation damage.

Adjuvants, Immunologic↗

PubMedDate not supplied

Identification of the translocating bacteria in rats with acute liver injury and their relation to the bacterial flora of the intestinal mucosa.

The bacterial flora of the intestine and the bacteria found in liver, mesenteric lymph nodes, portal and arterial blood after D-galactosamine-induced liver injury, with and without pretreatment with Lactobacillus plantarum DSM 9843, were studied in the rat. Dominating representatives were identified to species level by 16S rDNA sequencing and typed by randomly amplified polymorphic DNA (RAPD) and by restriction endonuclease analysis (REA) for strain definition. It was proven that bacterial strains from the intestine occur at extraintestinal sites after liver injury. Lactobacillus spp. dominated the intestinal flora and were also the most frequently found genus in the liver and the mesenteric lymph nodes. Some of the blood isolates, identified as Staphylococcus aureus, Proteus vulgaris and Bacteroides merdae, were not found as a dominating part of the mucosal flora. Treatment with L. plantarum before liver injury decreased translocation and made the intestinal flora increasingly dominated by lactobacilli.

Acute Disease↗

PubMed1999

Porosity of the epithelial basement membrane as an indicator of macrophage-enterocyte interaction in the intestinal mucosa.

The epithelial basement membrane of intestinal villi is perforated with numerous small pores, through which free cells in the lamina propria communicate with the enterocytes. This study was a comparative analysis of the pores in the basement membrane by SEM after removal of the gut epithelium with OsO4 maceration. The porosity as represented by the area fraction of the pores varied along the baso-apical axis of villi in patterns specific for each animal species examined: consistent scantiness along the entire length of villi in mice, acute elevation in the second and third distal one-sixths of villi in rats, and gradual augmentation toward the villus tips in guinea pigs. Size distribution analyses of the pores indicated their heterogeneous enlargement in the regions of elevated porosity. Concomitant observation of lamina propria macrophages by histochemical labelings and by conventional TEM showed that the cells specifically clustered beneath the hyperporous basement membrane, with their thick processes penetrating it. The spatially-regulated patterns of perforation of the epithelial basement membrane indicate phase-specific interventions of lamina propria macrophages in the maturation or aging of enterocytes, which steadily proliferate in crypts and exfoliate at the villus tips.

Animals↗

PubMed1975

[Specificity of action of phospholipases of rat intestinal mucosa].

The total homogenate of rat intestine is devoid of C or D phospholipase activity. At pH 6,5 in the presence of phosphatidylcholines, it exhibits a B phospholipase activity and in the presence of exogen lysophosphatidylcholines an A1 lysophospholipase activity. At pH 8,5 the intestinal mucous membrane of a rat shows an isolated A2 phospholipase activity.

Animals↗

PubMed1982

Peptide-containing innervation of the human intestinal mucosa. An immunocytochemical study on whole-mount preparations.

The three-dimensional distribution of the peptide-containing innervation in the human intestinal mucosa was studied by fluorescence immunohistochemistry on whole-mount mucosal preparations. An extensive VIP-immunoreactive nerve supply was demonstrated at all levels, but was markedly increased in density in the distal intestine, where it formed a particularly rich network in close contact with the luminal epithelium. In contrast, substance P-containing nerve fibres formed a looser and evenly distributed innervation at all levels. The muscularis mucosae was richly supplied by VIP- and substance P-containing fibres. Met-enkephalin immunoreactivity was confined to a few scattered nerve bundles running in the muscularis mucosae and around the bottom of epithelial crypts.

Animals↗

PubMed2004

Effect of dietary restriction and N-acetylcysteine supplementation on intestinal mucosa and liver mitochondrial redox status and function in aged rats.

The age-related changes of glutathione (GSH) levels and the effect of hypocaloric regimen and N-acetylcysteine (NAC) supplementation were investigated in intestinal mucosa and liver mitochondria of 28 months rats. Old rats exhibited lower proteins, GSH and protein sulphydrils (PSH) concentrations, higher GSH-peroxidase (GSH-Px) activity and protein carbonyl deposit, partial inhibition of succinate stimulated mitochondrial state III respiration and decreased mitochondrial nitrosothiols (RSNO) concentration. Lower electric potential and current intensity were found in the colonic mucosa. Old rats undergone hypocaloric regimen showed higher intestinal concentrations of GSH, lower oxidized protein accumulation and GSH-Px activity and higher mitochondrial RSNO levels. Mitochondrial state III respiration and intestinal transport were improved. NAC supplementation enhanced GSH and PSH levels in the ileal but not in the colonic mucosa, GSH and RSNO in liver mitochondria, while GSH-Px and protein carbonyls were decreased everywhere. Mitochondrial respiration ameliorated. In conclusion, ageing is characterized by a spread decrease of GSH concentrations, increased protein oxidation and decreased mitochondrial NO content. Hypocaloric diet ameliorated intestinal transport and, as well as NAC, was effective in enhancing GSH levels but at different extent according to the investigated districts. Both interventions reduced the age-associated increase of GSH-Px and protein carbonyls and improved mitochondrial respiration.

Acetylcysteine↗

PubMed1988

The response of the intestinal mucosa to prostaglandin E2 during withdrawal from morphine.

Experiments were designed to determine whether the diarrhoea characteristic of morphine withdrawal results from an enhanced sensitivity of the intestinal mucosa to PGE2. Rats (250-300 g) were made morphine-dependent by subcutaneous injection of an emulsion releasing 300 mg morphine HCl over 48 h. In-vivo, the transintestinal potential difference (PD) responses to PGE2 (4.6-46 micrograms kg-1 i.v.), which reflect increased Cl secretion, were significantly larger in withdrawn (morphine emulsion, 10 mg kg-1 naloxone s.c.) compared with non-dependent animals (emulsion only, naloxone s.c., P less than 0.05). Muscle-stripped intestinal sheets from dependent animals incubated with naloxone (10(-5) mol L-1) in-vitro did not demonstrate a greater electrical response (PD, short circuit current) to PGE2 (1.4 x 10(-6) mol L-1) than sheets taken from non-dependent animals. In-vitro preparations from animals withdrawn in-vivo did not respond differently from tissue taken from non-dependent animals (naloxone 10 mg kg-1 s.c., 10(-4) mol L-1 in medium, in both groups). This occurred in whole sheets of intestine as well as sheets without attached muscle. Jejunal fluid absorption in-vivo was lower in withdrawn animals than in non-dependent animals. However, the responses to intra-arterial infusion of PGE2 were similar in both groups with 2 micrograms min-1 inhibiting absorption and 4 micrograms min-1 inducing secretion. In-vivo, PGE2-induced Cl secretion appears to be enhanced during withdrawal although net fluid transport is not altered, suggesting different effects of the withdrawal process on the electrogenic Cl secretory and neutral NaCl absorptive mechanisms.

Animals↗

PubMed1993

A comparison of beta-carotene-splitting activity isolated from intestinal mucosa of pasture-grazed sheep, goats and cattle.

The in vitro enzymatic conversion of beta-carotene to retinal by partially purified preparations from the intestinal mucosa of sheep, goats and cattle was demonstrated. At pH 7.8 and 37 degrees C, this enzyme from sheep, goats and cattle displayed Michaelis-Menten type kinetics with a Vmax (nmol substrate split/mg protein/h) of 0.21, 0.27, and 0.04 and an apparent Km of 4.66 x 10(-6) M, 13.4 x 10(-6) M and 1.27 x 10(-6) M respectively. Maximal reaction was obtained by addition of an appropriate combination of detergent and bile salt, sodium dodecyl sulphate and egg lecithin. The cattle enzyme was inhibited by sodium glycocholate. The activity of sheep enzyme was higher (P < 0.05) than that of goats and cattle. The measured activity of the preparations from sheep, goats and cattle grazed on the same pasture reflected their contents of the reaction product, retinol, in the liver.

Animal Feed↗

PubMed1986

Inducing effects of clofibric acid on 1-acylglycerophosphorylcholine acyltransferase in kidney and intestinal mucosa of rats.

Administration of p-chlorophenoxyisobutyric acid (clofibric acid) markedly increased the activity of microsomal 1-acylglycerophosphorylcholine (1-acyl-GPC) acyltransferase in kidney, intestinal mucosa and liver, but not in brain, heart, lung, spleen, testis or skeletal muscle. In both kidney and liver, a marked dose-dependent increase in the activities of both microsomal 1-acyl-GPC acyltransferase and peroxisomal beta-oxidation was observed. In the rats treated with clofibric acid at a relatively low dose, the increase in the activity of 1-acyl-GPC acyltransferase in kidney was more marked than that in liver. The extent of the relative increase in the activity of 1-acyl-GPC acyltransferase to the activity of peroxisomal beta-oxidation in kidney was more marked than that in liver. The increased activity of 1-acyl-GPC acyltransferase in both kidney and liver lasted throughout the 8-week treatment period of rat with clofibric acid.

1-Acylglycerophosphocholine O-Acyltransferase↗

PubMed1980

Induction of an ornithine decarboxylase-antizyme by diaminopropane in chicken kidney and intestinal mucosa.

Administration of diaminopropane to chickens, injected with insulin in order to induce ornithine decarboxylase, prevents the increase of the decarboxylase activity in kidney and in the intestinal mucosa, not in the heart, In the first two tissues, not in the last one, an ornithine decarboxylase-antizyme is detected. The ornithine decarboxylase-antizyme appears therefore to be involved in vivo in the regulation of ornithine decarboxylase activity.

Animals↗

PubMed2004

Starch microparticles as oral vaccine adjuvant: antigen-dependent uptake in mouse intestinal mucosa.

An oral vaccine formulation comprised of starch microparticles with conjugated antigens is being developed. In this report we have examined the uptake of such microparticles by the intestinal mucosa and examined whether the conjugated antigen can influence the uptake. Two model antigens were used: recombinant cholera toxin B subunit (rCTB), which is known to bind to the ubiquitous GM1-receptor, and human serum albumin (HSA) which is not known to have any specific binding properties. The uptake was studied in mouse ligated intestinal loops into which the microparticles were injected. The intestinal loops were excised, fixed in ice-cold 95% ethanol. Entire specimens were mounted, exposed to fluorescence-labeled reagents staining the cytoskeleton, the particles and/or M cells and examined in a confocal laser-scanning microscope. A qualitative difference in the uptake of the rCTB- and HSA-conjugated microparticles was seen. The rCTB-conjugated microparticles were found both in villi and in the follicles of the Peyer's patches. HSA-conjugated microparticles could only be detected in the follicles of the Peyer's patches and not in villi. The rCTB conjugated to the microparticles did not lose its ability to bind the GM1-receptor, as shown with a GM1-ELISA, and the uptake of rCTB-conjugated microparticles in villi is most probably facilitated by the rCTB binding to the GM1-receptor. The qualitative difference in uptake could be of importance for the development of an immune response as the cytokine and chemokine microenvironment during antigen presentation will decide the differentiation of the immune response induced.

Adjuvants, Immunologic↗