[ISOLATION OF BRUSH BORDER REGION FROM THE SMALL-INTESTINAL MUCOSA IN RATS].
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Intestinal Mucosa↗
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Inhibitory effect of bovine serum albumin on acid deoxyribonuclease from rat small intestinal mucosa.
Bovine serum albumin was found to have an inhibitory effect on acid DNase from rat small intestinal mucosa. The inhibitory activity showed pH-dependency. Thus, the highest inhibition was observed at about pH 4.3 but conversely the enzyme was activated at about pH 4.7. The inhibitory effect was heat-inactivated most strongly at about pH 5, but at more acidic or alkaline pHs, no inactivation was observed. Inhibitory activities of serum albumin of various species were comparable with that of bovine serum albumin. Acid DNases from guinea pig kidney and small intestinal mucosa and from rat spleen and kidney were similarly inhibited by the albumin. The acid DNase displays typical Michaelis-Menten kinetics but the kinetics became sigmoidal in the presence of the inhibitor. With increasing inhibitor concentration, the sigmoidal shape became more pronounced, and at high concentration, the DNA was able to compete with the inhibitor and to reverse its action. Among the cyanogen bromide-cleaved fragments of bovine serum albumin, fragment C (derived from the carboxyl-terminal two-thirds of the albumin) had an inhibitory effect comparable to that of intact bovine albumin, but fragment N (derived from the amino-terminal one-third of the albumin) had no activity. Reduced fragment C showed a markedly decreased effect and lost the activity completely after separation into its three component peptides. Acetylation of bovine serum albumin completely destroyed its inhibitory activity.
Animals↗
[Isolation and features of the functioning of mitochondria of the small intestine mucosa in the rat].
A modification is suggested for the method of intact mitochondria isolation from rat thin intestine mucosa. Mitochondria are obtained which can in vitro transport Ca2+ simultaneously with phosphorylation of the added ADP. Kinetic advantages of succinate in providing oxidative phosphorylation as compared with NAD-dependent substrates are much more pronounced in mitochondria of the thin intestine mucosa than in other tissues, and Ca2+ transport occurred only under succinate oxidation. As compared with liver mitochondria these mitochondria are shown to be more sensitive to adrenaline and calcium action.
Adenosine Diphosphate↗
Immunohistochemical studies of the immunoglobulin-producing cell systems of the human intestinal mucosa.
Since the reliability of immunohistochemical observations is highly dependent on the quality of the immunological reagents, the importance of purification, characterization and performances testing of the fluorochrome conjugates is discussed. The methods of tissue processing, immunohistochemical staining and differential enumeration of fluorescing cells used in our laboratory are described. The normal intestinal mucosa shows a striking preponderance (80-90%) of IgA immunocytes, and these cells produce J chains which are incorporated into dimeric IgA. The dimers are taken up by the columnar epithelial cells which produce "secretory component" (SC). Complexing of dimeric IgA with SC seems to explain the selective transport of IgA through the crypt epithelium. A similar transport mechanism operates for J-chain-containing pentameric IgM. Marked alterations of the intestinal immunocyte populations are seen associated with various bowel diseases. In coeliac disease and dermatitis herpetiformis, a numerical increase takes place for all Ig-producing cell classes--in relative terms most prominent for IgG and IgM cells. In ulcerative colitis and Crohn's disease, the IgG-cell response is very striking, In alpha-chain disease, the lamina propria is infiltrated with IgA cells that lack light-chain-producing capacity but show some ability to synthesize J chains; dimers of alpha chain are hence transported to the intestinal lumen but cannot function as antibodies. In patients with a complete and selective lack of IgA in serum, IgA-producing cells are absent from the intestinal mucosa, and there is a numerical increase of local IgG- and specially IgM-producing cells. Conversely, patients with a partial deficiency of serum IgA may show a fairly normal intestinal IgA-cell population, although the proportion of IgM-producing cells is often increased. The intestinal mucosa of patients with a generalized hypogrammaglobulinaemia is sometimes devoid of plasma cells, but rare Ig-producing immunocytes, especially of the IgM class, are often seen. Supported in part by the Norwegian Research Council for Science and the Humanities, Anders Jahres Fond, and Helga Sembs fond. We thank Ms. Evy Eriksen and Ms. Gummvor Oijordbakken for technical assistance, and Ms. Liv Støottum for typing the manuscript.
Adolescent↗
Effects of phosphorothioate oligodeoxynucleotide on hemoglobin-induced damage to intestinal mucosa.
Some "blood substitutes," such as human diaspirin cross-linked hemoglobin DBBF-Hb, can damage the intestinal mucosa. This response may be due to release of free iron from Hb leading to production of reactive oxygen species (ROS). Phosphorothioate oligodeoxynucleotides can bind and sequester iron. Therefore experiments were performed to test whether PS-ODN, composed of ten consecutive cytidines "C-10," reduces Hb-induced ROS generation and damage in the mucosa. Anesthetized Sprague-Dawley rats (4-6 per group) were injected arterially with 1 mg C-10, followed two minutes later by 50 mg DBBF-Hb. The positive controls received only DBBF-Hb and the negative controls either saline or PS-ODN followed by saline. Either ROS formation was monitored using a fluorescence technique, or the intestine was fixed for microscopy after 8 or 30 min. Sixty villi per rat were assigned an epithelial integrity index (EI), ranging from 1 (intact) to 3 (some cell-cell and cell-basement membrane separation). Pretreatment with PS-ODN significantly exacerbated DBBF-Hb-induced ROS formation, and PS-ODN groups showed significantly more epithelial damage near Peyer's patches, (EI of 1.93 +/- 0.06 (SEM) at 8 minutes and 1.31 +/- 0.04 at thirty minutes), than the negative controls, (1.11 +/- 0.02 at both 8 and 30 minutes), or the positive controls (1.43 +/- 0.05 at 8 minutes and 1.20 +/- 0.03 at 30 minutes) (p < 0.05). However, mast cell degranulation, eosinophil accumulation and goblet cell secretion were significantly reduced in the DBBF-Hb groups pre-treated with PS-ODN. Thus, PS-ODN, although an iron chelator, can significantly enhance epithelial damage caused by DBBF-Hb in the rat intestinal mucosa near Peyer's patches, possibly by formation of the ferryl component of the hemoglobin.
Animals↗
Acid lipase in rat intestinal mucosa: physiological parameters.
Previous studies have shown that up to a half of infused triacylglycerol does not exit the intestine via lymphatics. This suggests the presence of a mucosal lipase which could provide fatty acids for potential transport via the portal vein. The present study describes an acid-active lipase in rat intestinal mucosa. Acid lipase was assayed using a glyceryl tri[14C]oleate emulsion (pH 5.8). Mucosal homogenates were differentially centrifuged to yield cellular organelles and cytosol. Cells were sequentially released from villi using citrate and EDTA. The enzyme was found to be most active in the proximal quarter intestine and in the upper third of villi. Its greatest activity was in the lysosomal fraction. Esophageal diversion demonstrated that lingual lipase was not the precursor of the mucosal acid lipase. Bile salts stimulated activity 3- to 5-fold, but other neutral or anionic detergents were inhibitory. Of the detergents tested, taurocholate at super critical micellar concentrations could restore activity only with SDS. Sepharose 6B chromatography suggested that the enzyme partitioned into an SDS and taurocholate mixed micelle. We conclude that mucosal acid lipase is a distinct, intrinsic enzyme of the intestinal mucosa. It is predominantly lysosomal in origin. The location of its greatest activity in the villus tips of the proximal intestine suggests that it is potentially involved in mucosal triacylglycerol disposal.
Acid Phosphatase↗
Localization of immunoreactive secretory leukocyte protease inhibitor (SLPI) in intestinal mucosa.
Secretory leukocyte protease inhibitor (SLPI) is the dominant protease inhibitor in the mucus secretions of the repiratory and genital tracts, and local production seems likely, as immunoreactive SLPI has been found in the corresponding mucosa. To our knowledge, SLPI has not been previously demonstrated in intestinal epithelia or secretions. In an earlier study, however, we found surprisingly high levels of SLPI in peritonitis exudate from patients with gastrointestinal perforations. This study extends these observations by demonstrating the presence of immunoreactive SLPI in intestinal mucosa. In the small intestine, SLPI was present in Paneth cells and in scattered mucosa cells of goblet-type. In normal mucosa of the large bowel, SLPI was also found in scattered cells of goblet-type in the epithelium. In addition, immunoreactive SLPI was frequently found in colonic adenomas. The findings in this study raise several interesting questions on the possible role of SLPI in the gut epithelial defense against inflammatory assaults.
Adenoma↗
A soluble flavonoid-glycoside, alphaG-rutin, is absorbed as glycosides in the isolated gastric and intestinal mucosa.
We investigated the absorption and metabolism of the highly soluble quercetin glycoside alphaG-rutin, a glucose adduct of insoluble rutin, using the isolated mucosa of the rat stomach and intestines equipped with the Ussing chamber. alphaG-rutin and rutin appeared in the serosal sides of the gastric body and all the intestinal mucosa after the addition of alphaG-rutin (1 mM) to the mucosal fluid. The degree of alphaG-rutin appearance was much lower in the gastric fundus than in the other parts. Quercetin was not found in the mucosal fluid of any mucosal specimen. The concentrations (microM) of alphaG-rutin and rutin in the serosal fluid as a result of transport from the mucosal side increased time-dependently and linearly with mucosal alphaG-rutin concentration (1, 10 or 100 mM). The highest transport was shown in the ileal mucosa. These results indicate that alphaG-rutin is partly hydrolyzed to rutin through the intestine and absorbed as such.
Animals↗
Identification of possible chicken intestinal mucosa receptors for SEF21-fimbriated Salmonella enterica serovar Enteritidis.
In order to test whether glycosphingolipids (GSLs) on the chicken intestinal mucosa serve as a receptor for Salmonella enterica serovar Enteritidis with fimbriae, we analyzed neutral GSLs and gangliosides from chicken intestinal mucosa and investigated the binding of bacteria to neutral GSLs and gangliosides. Four kinds of neutral GSLs, designated as N-1 to N-4 and four kinds of gangliosides, named G-1 to G-4, were identified on high-performance thin-layer chromatography (HPTLC) plates. In TLC immunostaining tests, fimbriated S. Enteritidis bound only to glucosylceramide (GlcCer) standard, N-1, GM3 standard and G-1, but neither to N-2, N-3, N-4, nor to G-2, G-3 and G-4. Further, the bacterial binding to N-1 and G-1 was completely inhibited by preincubation of bacteria with anti-S. Enteritidis fimbriae (SEF) 21 antibody, but not by anti-SEF14 antibody. These results suggest that both GlcCer (N-1) and ganglioside GM3 (G-1) on the epithelial cell surfaces of chicken intestine act as receptors for fimbriated S. Enteritidis.
Animals↗
Changes of occludin expression in intestinal mucosa after burn in rats.
In severely burned rats, hyperemia, edema and other pathological injuries occur in the intestinal mucosa. Ultramicroscopically, the microvilli, tight junction and organelles are disrupted. Occludin is a functional component of tight junctions. The purpose of the present study is to investigate changes of occludin expression, and to further elucidate the relationship between occludin expression and ultrastructure damage. The fluorescence intensity of occludin was detected in intestinal wall by the method of immunofluorescence histochemistry and confocal laser scanning microscopy (CLSM). Expression of occludin and its mRNA were determined by western blotting and RT-PCR, respectively. Changes of intestinal mucosa ultrastructure were observed by TEM. The results showed that fluorescence intensity of occludin at 3PBH was enhanced, higher than that of the control group, being 80.77+/-8.38 and 72.86+/-4.74, respectively, and reached a peak at 12PBH (116.14+/-6.89). The expression levels of occludin at 3PBH and 6PBH were 1.21+/-0.02 and 1.53+/-0.14 times that of the control group, respectively, and there were significant differences (P<0.01) between 3PBH group and 6PBH group and control group. The levels of occludin mRNA were also enhanced. At 12PBH, the level reached a peak (P<0.01), being 2.00+/-0.24 times that of the control group. Coincidently, the structure of the tight junction between epithelial cells was disrupted on a large scale under TEM. We speculate that up-regulation of epithelial occludin may play a role in enhancing paracellular permeability and be related to the damage to the tight junction.
Animals↗
[Characteristics of cyclic nucleotide phosphodiesterase and calmodulin in the small intestinal mucosa of rabbits].
Some aspects of the functioning of phosphodiesterase of cyclic nucleotides and calmoduline of the small intestinal mucosa were examined. It was shown that Ca2+ ions virtually have no effect on phosphodiesterase activity of the mucosal homogenate. Cytosol chromatography on a DEAE-cellulose column makes it possible to find an activating effect of calmoduline on phosphodiesterase. Minor quantities of this form of the enzyme might activate the total rate of cAMP hydrolysis with Ca2+ ions for not more than 10%. The author describes calmoduline from the intestinal mucosa as a low-molecular, thermostable protein of acid nature, whose effect can be detected only in the presence of Ca2+ ions.
2',3'-Cyclic-Nucleotide Phosphodiesterases↗
Intestinal mucosa in diabetes: synthesis of total proteins and sucrase-isomaltase.
The effects of insulin deficiency on nitrogen metabolism in muscle and liver have been extensively studied with recent in vivo demonstration of impaired protein synthesis in rats with streptozotocin-induced diabetes. Despite the significant contribution of small intestinal mucosa to overall protein metabolism, the effects of insulin deficiency on intestinal protein synthesis have not been completely defined. We studied the effects of streptozotocin-induced diabetes on total protein synthesis by small intestinal mucosa and on synthesis of a single enzyme protein of the enterocyte brush-border membrane sucrase-isomaltase. We used the flooding-dose technique of McNurlan, Tomkins, and Garlick (Biochem. J. 178: 373-379, 1979) to minimize the difficulties of measuring specific radioactivity of precursor phenylalanine and determined incorporation into mucosal proteins and sucrase-isomaltase 20 min after injection of the labeled amino acid. Diabetes did not alter mucosal mass as determined by weight and content of protein and DNA during the 5 days after injection of streptozotocin. Increased rates of sucrase-isomaltase synthesis developed beginning on day 3, and those of total protein developed on day 5. Thus intestinal mucosal protein synthesis is not an insulin-sensitive process.
Animals↗
Influence of microcystin-LR on the activity of membrane enzymes in rat intestinal mucosa.
The objective of the present study was to evaluate the effects of microcystin-LR (MCLR) on the activity of membrane enzymes from intestinal mucosa. In addition, serum chemistry and peroxidative status of both serum and intestinal homogenate were evaluated after treatment with MCLR. Wistar rats were treated with intraperitoneal injection of either 100 microg pure MCLR/Kg body weight or saline solution. A significant increase in liver weight and altered serum enzyme activities were found in MCLR-treated rats, indicating damage to the liver in these rats, as previously suggested. A higher specific activity of sucrase (1.5-fold) was observed after the administration of MCLR, whereas other intestinal apical membrane enzymes, such as lactase, maltase and alkaline phosphatase were not modified by the treatment. The specific activities of acid phosphatase and succinate dehydrogenase, markers for lysosomal and mitochondrial membranes, respectively, were also increased (32% and 60%, respectively) in treated rats. The analysis of lipid peroxidation showed that the peroxidative status was increased in both serum and intestinal mucosa from MCLR-treated rats, reflecting an excess production of oxygen free radicals induced by this cyanobacterial toxin. In conclusion, this study shows that acute exposure to MCLR affects the intestinal physiology by modifying the intestinal peroxidation status as well as the activity of membrane enzymes.
Animals↗
Metabolism of heme and bilirubin in rat and human small intestinal mucosa.
Formation of heme, bilirubin, and bilirubin conjugates has been examined in mucosal cells isolated from the rat upper small intestine. Intact, viable cells were prepared by enzymatic dissociation using a combined vascular and luminal perfusion and incubated with an isotopically labeled precursor, delta-amino-[2,3-3H]levulinic acid. Labeled heme and bile pigment were formed with kinetics similar to those exhibited by hepatocytes. Moreover, the newly formed bilirubin was converted rapidly to both mono- and diglucuronide conjugates. In addition, cell-free extracts of small intestinal mucosa from rats or humans exhibited a bilirubin-UDP-glucuronyl transferase activity that was qualitatively similar to that present in liver. The data suggest that the small intestinal mucosa normally contributes to bilirubin metabolism.
Aminolevulinic Acid↗
Multiple accumulation of Vdelta2+ gammadelta T-cell clonotypes in intestinal mucosa from patients with Crohn's disease.
The gammadeltaT cells have been known to play an important role in the regulation of the mucosal immune system, but the relationship between these cells and the pathogenesis of Crohn's disease (CD) has remained obscure. We now demonstrate the T-cell receptor (TCR) Vdelta2 gene transcripts characterize antigenic immune response in the intestinal mucosa from patients with CD. TCR Vdelta2 gene transcripts of six patients with CD and six controls were subcloned and 20 randomly selected clones from each sample were subjected to nucleotide sequencing. Sequence analysis demonstrated that the different clones in the intestinal mucosa of CD were significantly increased (11.833 +/- 0.946) compared to controls (7.167 +/- 1.470) (P = 0.0374). The presence of intraindividual dominance and oligoclonality of TCR Vdelta2 gene transcripts in normal controls appears reflect positive selection and expansion of specific gammadelta T cells in normal controls. By contrast TCR Vdelta2 gene transcripts in the intestinal mucosa of CD can express different clonotypes. We conclude that accumulation of multiple Vdelta2+ gammadelta T-cell clonotypes are involved in the pathogenesis of CD.
Adolescent↗
[Functional activity of mitochondria and intensity of nucleic acid and protein synthesis in rat liver and small intestine mucosa with different supplies of vitamin D].
Decrease in total content of mitochondrial protein in mucosa of small intestine, an alteration of distribution of the protein between the fractions of mitochondria, distinct decrease in the respiratory activity of mitochondria and in the activity of succinate- and NADH-dehydrogenases were observed in rats deficient in vitamin D. Deficiency in vitamin D was accompanied by decreased incorporation of labelled precursors into total, nuclear and mitochondrial DNA and RNA by 20-50% and into mitochondrial proteins--by 50% in mucosa of small intestine; these patterns were unaltered in liver tissue. Administration of ergocalciferol (at a dose 1000 IU) into rats normalized the impairments studied, whose alteration correlated with the increase of calcium concentration in blood serum.
Animals↗
Dipeptidase activity in the small intestinal mucosa during pregnancy and lactation in the rat.
1. Rats were mated and at weekly intervals during pregnancy and lactation, and after weaning, the dipeptidase activity in the supernatant fraction from small intestinal mucosa extracts was determined for two dipeptides: glycyl-L-leucine dipeptidase (EC 3.4.3.2) AND L-alanyl-L-glutamic acid dipeptidase. 2. Dipeptidase activity is found mainly in the soluble (spernantant) fraction of the mucosa homogenate. 3. Compared with those values obtained for unmated controls, the food consumption of the animals and the nitrogen content, total and specific activities of the dipeptidases (per unit quantity of N) in the soluble fraction of the small intestinal mucosa extracts increased slightly during pregnancy and markedly during lactation. After the pups were weaned, values for all these measurements fell rapidly. 4. Whether the increases found in enzyme activity were simply a response to increased food intake or were the result of hormonal stimulus is discussed.
Alanine↗
[Comparative characteristics of microsomal epoxide hydrolase in the rat liver and small intestine mucosa].
Activity of epoxide hydrolase was studied in microsomes of rat liver and small intestinal mucosa with styrene oxide as substrate using high performance liquid chromatography. Specific activity of epoxide hydrolase in microsomes from small intestine constituted 5-10% of the activity in liver microsomes. Both these enzymes had similar kinetic parameters, the same pH optimum around pH 8.7; their activity was altered only slightly in presence of anionic detergents. The enzyme activity was increased in liver and small intestine after administration of benzyl, trans-stilbene oxide, 2-acetamidofluorene and butylated hydroxytoluene. 1,2-epoxy-3,3,3-trichloropropane and 2-brom-4-nitroacetophenon inhibited similarly epoxide hydrolase in hepatic and intestinal microsomes. Cyclohexene oxide inhibited both these enzymes by the non-competitive type, exhibiting the higher affinity to liver epoxide hydrolase.
Animals↗