Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We determined the dependence of the frequency of lactose intolerance, particular features of the clinical presentation and laboratory showings on lactase deficiency on the basis of a complex clinical, anamnestic and laboratory study of 149 children with chronic gastroduodenal pathologies. It was established that the prevalence of lactose intolerance in children with superficial gastroduodenitis amounts to 58.8%, in children with erosive gastroduodenitis--66.7% and in children with stomach ulcers--83.3%. During the oral lactose load and a subsequent laboratory study we revealed an impairment of the hydrolytic function of small intestines accompanied by an increase of fecal excretion of carbohydrates (lactose and monosaccharides) as well as a considerable enhancement of bacterial fermentation. The detection of fecal excretion of the total glycoprotein hexoses characterizes a disorder of the morphofunctional state of the gastrointestinal tract in children with intestinal enzymopathies.
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PMID:[Lactose tolerance in children with chronic gastroduodenal zone diseases]. 1287 8

Human colon adenocarcinoma cells (HT29-ATCC) and the clone HT29-5F7 were cultured under conditions that differentiate cells to a polarized intestinal phenotype. Differentiated cells showed the presence of junctional complexes and intercellular lumina bordered by microvilli. Intestinal brush border hydrolase activities (sucrase, aminopeptidase N, lactase and maltase) were detected mainly in differentiated HT29-ATCC cells compared with the differentiated clone, HT29-5F7. The presence of non-GM1 receptors of Escherichia coli heat-labile enterotoxin (LT-I) on both types of differentiated HT29 cells was indicated by the inability of cholera toxin B subunit to block LT-I binding to the cells. Binding of LT-I to cells, when GM1 was blocked by the cholera toxin B subunit, was characterized by an increased number of LT-I receptors with respect to undifferentiated control cells. Moreover, both types of differentiated cells accumulated higher amounts of cyclic AMP in response to LT-I than undifferentiated cells. Helix pomatia lectin inhibited the binding of LT-I to cells and the subsequent production of cyclic AMP. LT-I recognized blood group A-active glycosphingolipids as functional receptors in both HT29 cell lines and the active pro-sucrase form of the glycoprotein carrying A-blood group activity present in HT29-ATCC cells. These results strongly suggest that LT-I can elicit an enhanced functional response using blood group A-active glycoconjugates as additional receptors on polarized intestinal epithelial cells.
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PMID:Functional interaction of Escherichia coli heat-labile enterotoxin with blood group A-active glycoconjugates from differentiated HT29 cells. 1688 90

Lactase-phlorizin hydrolase (LPH), a membrane-bound glycoprotein present in the luminal surface of enterocytes in the intestine is responsible for lactose intolerance, a phenomenon prevalent in humans worldwide. In the rodent intestine, the post-natal development of the LPH follows a specific pattern, such that the enzyme levels are high in the peri-natal period, but declines considerably upon maturation. The observed maturational decline in the LPH activity is very similar to adult-type hypolactasia observed in humans. Majority of the studies have been carried out using animal models or cell lines and a number of hypotheses have been put forward to explain the maturational decline of lactase activity such as: (a) decreased amount of lactase protein, (b) defect in post-translational modification of precursor lactase to the mature enzyme, and (c) synthesis of an inactive, high molecular weight lactase with altered glycosylation, however, the precise underlying mechanism of adult-type hypolactasia remains undefined. The present review describes the recent developments in understanding the regulation of lactase expression and the possible mechanism of adult-type hypolactasia, as a cause of lactose intolerance.
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PMID:Hypolactasia as a molecular basis of lactose intolerance. 1713 32

Human milk stimulates intestinal development through the effects of various moieties. Lactoferrin (LF) is a glycoprotein of human milk whose concentration is highest in colostrum decreasing in mature milk. LF promotes enterocyte growth in intestinal cell lines. We tested the hypothesis that LF induces a distinct effect on enterocyte proliferation and differentiation, depending on its concentration. We examined the dose-related effects by human-native LF (N-LF) in Caco-2 (human colon adenocarcinoma) cells. At high concentrations, N-LF stimulated cell proliferation in immature Caco-2 cells, as judged by 3H-thymidine incorporation. In contrast, sucrase and lactase activities were increased at low but not high LF concentrations and their mRNA were also increased, indicating a transcriptional effect. Because iron binds specific LF sites, we compared the potency of N-LF and iron-saturated LF (I-LF) and found the native form more potent. Finally, we tested the effects by bovine LF (bLF) in the same system and found the latter more potent than the human isoform in inducing cell growth and lactase expression. These results suggest that LF directly induces enterocyte growth and proliferation, depending on its concentration, thereby regulating the earlyx postnatal intestinal development. bLF could be added to infant formula as a growth factor in selected intestinal diseases.
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PMID:Lactoferrin induces concentration-dependent functional modulation of intestinal proliferation and differentiation. 1751 63

Intestinal celiac disease (CD) is triggered by peptic-tryptic digest of gluten, known as Frazer's Fraction (FF), in genetically predisposed individuals. Here, we investigate the immediate effects of FF on the actin cytoskeleton and the subsequent trafficking of actin-dependent and actin-independent proteins in COS-1 cells. Morphological alterations in the actin filaments were revealed concomitant with a drastic reduction in immunoprecipitated actin from cells incubated with FF. These alterations elicit impaired protein trafficking of intestinal sucrase-isomaltase, a glycoprotein that follows an actin-dependent vesicular transport to the cell surface. However, the actin-independent transport of intestinal lactase phlorizin hydrolase remains unaffected. Moreover, the morphological alteration in actin is induced by direct interaction of this protein with gliadin peptides carrying the QQQPFP epitope revealed by co-immunoprecipitation utilizing a monoclonal anti-gliadin antibody. Finally, stimulation of cells with FF directly influences the binding of actin to Arp2. Altogether, our data demonstrate that FF directly interacts with actin and alters the integrity of the actin cytoskeleton thus leading to an impaired trafficking of intestinal proteins that depend on an intact actin network. This direct interaction could be related to the endocytic segregation of gliadin peptides as well as the delayed endocytic vesicle trafficking and maturation in gliadin-positive intestinal epithelial cells and opens new insights into the pathogenesis of CD.
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PMID:Impairment of protein trafficking by direct interaction of gliadin peptides with actin. 2166 41


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