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)

The effect of a new complex oligosaccharide (Bay g 5421) of microbial origin on human intestinal alpha-glucosidehydrolase activity was tested in mucosal homogenate from human small bowel biopsy specimens. The alpha-glucosidehydrolase inhibitor (alpha-GHI) exerted a potent inhibitory effect on glucoamylase, sucrase, and maltase, was minimally effective on isomaltase, and did not affect trehalase and lactase activity. Kinetic analysis revealed a fully competitive type of inhibition with a Ki of 1.3 x 10(-6) M; thus the inhibitor had a 15,000-fold higher affinity to the enzyme sucrase than its natural substrate sucrose. The new compound may prove to be useful in the study of carbohydrate maldigestion and malabsorption and may possibly be of therapeutic benefit in diabetes and obesity.
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PMID:Inhibition of human intestinal alpha-glucosidehydrolases by a new complex oligosaccharide. 44 22

To determine the validity of breath H2 measurements in detecting lactase deficiency, capillary blood glucose and breath H2 were measured after ingestion of 50 g lactose in 34 patients with abdominal symptoms or diarrhea. 18 patients had biopsy-proven lactase deficiency and 16 normal lactase activity. Blood glucose determination produced 2 false-positive results while breath H2 measurements provided 2 false-negative and 4 false-positive results.
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PMID:[Exhaled hydrogen test in the detection of lactase deficiency]. 44 12

Gluten withdrawal from the diet is occasionally used speculatively in the management of multiple sclerosis. To assess whether there might be any rational basis for such a measure we have undertaken morphological and biochemical studies of the jejunal mucosa in 14 patients with multiple sclerosis. All were found to have morphologically normal villi, and quantitative estimation of surface-to-volume ratios gave values which did not differ from control subjects. Intraepithelial lymphocyte counts were normal. Antigliadin antibody titres were not raised in any patient. Estimation of activity of the brush border disaccharidases (sucrase, lactase, and maltase (showed that the mean level of each enzyme did not differ significantly from control subjects. Analytical subcellular fractionation of the biopsies showed no changes in the distribution or activity of marker enzymes for the brush order, lysosomes, mitochondria, cytosol, peroxisomes, or endoplasmic reticulum. It is concluded that there are no gross morphological or biochemical abnormalities in the jejunal mucosa in patients with multiple sclerosis and, therefore, that the use of gluten-free diets cannot be justified on the assumption that these patients suffer from a coeliac-like lesion of the small intestine.
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PMID:Morphological and biochemical findings in jejunal biopsies from patients with multiple sclerosis. 44 78

Turnover in organ culture of human small intestinal membrane glycoproteins was measured by the pulse-chase technique, using 14C-glucosamine, 14C-fucose or 14C-leucine as tracers. Apparently, low degradation rates were found for the major high-molecular-weight proteins which co-migrated on SDS-polyacrylamide gels with maltase-glucoamylase, lactase-phlorizin-hydrolase and sucrase-isomaltase enzymic activities. In contrast, an unidentified glycoprotein appearing on gels next to alkaline phosphatase exhibited a higher degradation rate with an apparent half-life of about 30 h, this being similar to the half-life of total glycoprotein as measured in mucosal homogenates. The results obtained with the pulse-chase technique were confirmed by double isotope experiments using 14C-leucine and 3H-leucine as tracers. These findings indicate that in organ culture there is a low basic turnover of human intestinal membrane glycoproteins which co-migrate on gels with known glycosidase enzymic activities.
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PMID:Turnover studies of human intestinal brush border membrane glycoproteins in organ culture. 45 41

The breath hydrogen test (BHT) was adapted for use in young infants and children. The diagnostic criterion of sugar malabsorption in the BHT was determined by oral administration of 0.5 g/kg of unabsorbable sugar (lactulose) to 21 healthy infants and children. A maximum increase in breath hydrogen less than 0.05 ml/min per m2 was observed in all subjects. A good correlation between results by the BHT and by the ordinary lactose tolerance test was obtained after oral administration of 2 g/kg lactose to 21 healthy infants and children, 2 congenital lactase-deficient infants, and 7 adults. Using this test, 80 healthy Japanese infants and children (aged between one month and 15 years) and 18 adults were examined for lactose malabsorption after a dose of 1 g/kg lactose. All infants and children under 2-years old absorbed lactose completely. The incidence of lactose malabsorption was 30% in 3-year, 36% in 4-year, 58% in 5-year, and 86% in 6-year-old children, 85% in schoolchildren, and 89% in adults. Thus the incidence of lactase deficiency gradually increases with age from 3 years, and about 90% of all normal Japanese adults are lactase-deficient.
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PMID:Breath hydrogen test for detecting lactose malabsorption in infants and children. Prevalence of lactose malabsorption in Japanese children and adults. 47 26

Jejunal mucosal function and structure was examined in 31 patients with ulcerative colitis and 29 patients with Crohn's disease with ileal, ileocolonic or colonic involvement; A significant reduction of the specific activity of disaccharidases (lactase, sucrase and trehalase) in jejunal mucosal homogenate occurred in patients with inflammatory bowel disease. Similarly, alkaline phosphatase was reduced in ulcerative colitis. Several dipeptidases such as glycyl-leucine, leucyl-glycine, glycyl-glycine and valyl-proline hydrolase activities were lower in patients with inflammatory bowel disease than in controls. Histological changes in jejunal mucosal biopsies occurred in 71% of patients with ulcerative colitis and 61% with Crohn's disease. These changes ranged from mild abnormalities of villus architecture to marked reduction of villus height. Most patients with a reduction in mucosal enzymes had concommitant morphological changes in jejunal mucosal biopsy. The results of this study indicate that functional and structural abnormalities of the jejunal mucosa frequently occur in patients with inflammatory bowel disease without radiologic evidence of proximal small bowel involvement.
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PMID:Abnormalities of jejunal mucosal enzymes in ulcerative colitis and Crohn's disease. 47 7

To identify the site of stimulation of sucrase by a sucrose diet, changes in sucrase-specific activity of jejunal mucosa were studied after introduction of sucrose diet to carbohydrate-deprived rats. Results were correlated with simultaneous changes in villus gradients of sucrase-specific activity. Simultaneous with the introduction of sucrose diet, [(3)H]thymidine (100 muCi) was administered intravenously, and rates of cell migration measured during adaptation to the new diet. After a 72-h fast, rats fed sucrose diet for 6, 12, or 18 h showed no change in sucrase-specific activity in either whole mucosa or villus gradients. However, within 18-24 h after starting a sucrose diet, there was a marked rise in whole mucosal sucrase-specific activity above fasting values (99 +/- 14 vs. 38 +/- 4 muM glucose/min per g protein, P < 0.001) in association with the development of a region of increased activity at the lower villus (154 +/- 22 vs. 60 +/- 9 muM glucose/min per g protein, P < 0.02, but with no change in villus tip activity (56 +/- 5 vs. 46 +/- 8 muM glucose/min per g protein). Similar changes were seen in animals fed 24 h of sucrose diet after a 72-h carbohydratefree diet. Fasted animals fed sucrose diet for 36 h had increased sucrase-specific activity at the villus tip (144 +/- 11 muM glucose/min per g protein) as well as at the lower villus region, and this pattern persisted at 1 wk of sucrose diet. Maximal activity patterns for isomaltase and maltase paralleled those for sucrase, but the villus gradients for lactase were unaffected by sucrose diet. The region of maximal sucrase-specific activity always coincided with or followed the leading edge of radioactivity as determined by liquid scintillation counting. Therefore, sucrose-mediated changes in sucrase activity of the jejunal mucosa in the rat appear to be initiated at the level of the crypt epithelial cell and are expressed after a latent period of 18-24 h during which these cells mature and migrate toward the villus tip.
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PMID:Site of substrate stimulation of jejunal sucrase in the rat. 47 72

Lactose tolerance tests were performed on 75 healthy Lebanese volunteers, 12 patients with "Mediterranean lymphoma" and 15 American and West European Caucasians. Small intestinal biopsies were done on 10 intolerant and five tolerant subjects for histological evaluation and lactase assay. Lactose malabsorption was present in 78% of the Lebanese subjects, in all patients with Mediterranean lymphoma and in five of the 15 Caucasians. Two of the five intolerant Caucasians had giardiasis. There was no difference in the prevalence rate among the various Lebanese groups nor among males and females. Symptoms occurred in 91% of the 58 intolerant Lebanese subjects: diarrhea in 71%, abdominal distension in 67%, and cramps in 48%. The increased prevalence of lactose intolerance with Mediterranean lymphoma is probably secondary to the pathological changes in the intestinal mucosa and protein depletion.
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PMID:Lactose intolerance in the Lebanese population and in "Mediterranean lymphoma". 48 18

The roles of extracellular and intracellular mechanisms in the degradation of brush border proteins have been investigated by studying the small intestinal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency. Peroral jejunal biopsies were homogenised and the organelles separated by isopycnic centrifugation on continuous sucrose density gradients. The distributions of marker enzymes for the principal subcellular organelles were determined in the gradients and related to the specific activities in the homogenates. There were increased activities of the brush border carbohydrases zinc-resistant alpha-glucosidase, maltase and sucrase in the pancreatic insufficient animals, but no change in lactase activity. The activity of gamma-glutamyl transferase was also higher in the affected group; the activities of two other brush border enzymes, alkaline phosphatase and leucyl-beta-naphthylamidase, however, were unaltered. These findings with an increase in the modal density of the brush border from 1.20 to 1.22 are consistent with an enhanced glycoprotein content of the microvillus membrane. There were also rises in the activities of lysosomal enzymes. N-Acetyl-beta-glucosaminidase activity was increased in the soluble fractions and the percentage latent enzyme activity was reduced, findings indicative of an increased fragility of the lysosomal membrane. There were no marked alterations in the activities or density gradient distributions of marker enzymes for the other organelles, stressing the specificity of the changes in the brush borders and lysosomes. These findings are compatible with the degradation of certain exposed brush border proteins by pancreatic proteases and suggest that when this is defective, intracellular degradative mechanisms may be stimulated.
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PMID:Biochemical changes in the jejunal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency. 48 65

A case study is presented of a 57-year-old male who showed typical clinical features of Cronkhite-Canada syndrome. Numerous polypoid lesions were found in the stomach, duodenum, ileum, colon and rectum accompanied with characteristic ectodermal changes. Tests indicated a protein-losing gastroenteropathy. Intestinal lactase deficiency was demonstrated by the lactose tolerance test. Scanning electronmicroscopy of the gastric and colonic mucosa revealed prominent secretion of mucoid substances and distortion in the gastric pits and colonic crypts. These abnormal findings were interpreted as having a direct relationship to the loss of protein into the gastrointestinal tract.
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PMID:Cronkhite-Canada syndrome. A case report and analytical review of 23 other cases reported in Japan. 52 Jul 67


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