Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Lactase, sucrase, maltase, trehalase and alkaline phosphatase activities of rat proximal jejunum were measured in 3, 6, 9, 12, 18 and 24-month-old rats fed with diets differing in their fatty acid composition. 2. A drop of 47-53% of the specific enzyme activity was observed with disaccharidases against a decrease of 71% for alkaline phosphatase in the 24-month-old rats compared to the 3-month-old rats. 3. Changes in dietary fatty acid composition, either in the saturated or monounsaturated ratio, or in the polyunsaturated fatty acid composition, did not significantly interfere with this aging effect.
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PMID:Diet fatty acid composition, age and rat jejunal microvillus enzyme activities. 134 82

The brush border of normal small-intestine epithelial cells is rich in enzymes that are involved in the digestive process. Such molecules can be used as markers to analyze cell lineages and differentiation properties of colorectal cancers. Monoclonal antibodies detecting dipeptidyl peptidase-IV, aminopeptidase N, endopeptidase F, sucrase-isomaltase, alkaline phosphatase, maltase-glucoamylase and lactase have been used to analyze the phenotype of colorectal cancers, adjacent mucosa and histologically normal distant mucosa. The avidin-biotin peroxidase complex method was used. Expression of dipeptidyl peptidase-IV, aminopeptidase N, sucrase-isomaltase and alkaline phosphatase was common in non-neoplastic mucosa adjacent to, and distant from, the tumor; in contrast, endopeptidase F, maltase-glucoamylase and lactase were rarely expressed in normal distant mucosa and more frequently expressed in mucosa adjacent to the tumor. Dipeptidyl peptidase-IV, aminopeptidase N, endopeptidase F, sucrase-isomaltase and alkaline phosphatase were frequently expressed in colorectal cancers, whereas maltase-glucoamylase and lactase were rarely expressed. Two general patterns of antibody reactivity were observed: diffuse cytoplasmic and apical; apical reactivity was generally associated with more differentiated tumors. A logistic predictive regression model indicated that enzyme expression in colorectal cancers followed a coordinate pattern, but was unrelated to the location of the tumor, Dukes stage or differentiation grade. In conclusion, expression of brush-border-associated enzymes occurs frequently in colorectal cancers and is regulated in a co-ordinated manner. These markers can be used for the phenotypic sub-classification of colorectal cancers.
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PMID:Intestinal brush-border-associated enzymes: co-ordinated expression in colorectal cancer. 134 6

Expression of brush border hydrolases can reflect the state of differentiation of an epithelium. To determine if expression of these enzymes is disordered in patients with neoplastic or hyperplastic lesions, the activities of alkaline phosphatase, maltase, and dipeptidyl peptidase IV were measured spectrophotometrically in colonoscopic biopsies from the proximal and distal colon and rectum in 50 controls, 17 patients with large bowel adenomas, 29 with carcinoma, and 9 with hyperplastic polyps. In normal controls, a descending cecorectal gradient of alkaline phosphatase activities and an ascending gradient of maltase activities were seen (P < 0.001). Though regional patterns of expression were generally preserved in disease groups, there were significant differences of activities across patient groups for alkaline phosphatase (greater in cancer, adenoma, and hyperplastic groups than in normals; P < 0.05) and for dipeptidyl peptidase IV (greater in hyperplastic polyp group than normals, greater in adenoma than cancer group; P < 0.05). Compared with normal controls, abnormalities of site-specific activities were confined to the rectum in patients with adenoma (maltase decreased, P = 0.02; dipeptidyl peptidase IV increased, P < 0.01) or with carcinoma (alkaline phosphatase increased, P = 0.03) but dipeptidyl peptidase IV activities were increased in all regions in bowels bearing hyperplastic polyps (P < 0.01). These data suggest that neoplastic and hyperplastic lesions, while focal in nature, occur in large bowel epithelium, which is diffusely abnormal in terms of its expression of these enzymes.
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PMID:Neoplasia and hyperplasia of large bowel: focal lesions in an abnormal epithelium. 135 42

This study examines the effects of an enteropathogenic Escherichia coli on microvillar membrane proteins during organ culture of rabbit ileal explants. Explants maintained with enteropathogenic E coli showed brush border effacement affecting approximately 50% of enterocytes, and where enteropathogenic E coli were closely adherent to the enterocyte surface microvilli were apparently being shed as vesicles. The microvillar membrane enzymes alkaline phosphatase, aminopeptidase N and alpha-glucosidase were released into the culture medium during organ culture, and this process was significantly enhanced by enteropathogenic E coli. This increased loss of microvillar membrane enzymes into the culture medium was associated with decreased tissue activities of microvillar membrane enzymes in enteropathogenic E coli infected ileal explants compared with control. For aminopeptidase N in particular, however, total enzyme activities in the tissue plus culture medium were increased comparing enteropathogenic E coli with control, suggesting that there might be an increase in the rate of synthesis of certain microvillar membrane proteins. Reorientating sucrose density gradient centrifugation of culture medium showed that alkaline phosphatase, aminopeptidase N and alpha-glucosidase were predominantly associated with particles of peak modal density 1.19 g/ml in both groups, confirming that enteropathogenic E coli accelerate release of microvillar membrane enzymes as vesicles. Analytical fractionation of ileal explants showed that enteropathogenic E coli resulted in a loss of microvillar membrane enzyme activities from the main brush border peak of modal density 1.21 g/ml present in controls. The density of the remaining smaller and lighter peak increased from 1.19 g/ml to 1.23 g/ml after homogenisation in digitonin, confirming association of these proteins with cholesterol containing membranes and not endoplasmic reticulum. These findings suggest that enteropathogenic E. coli accelerate the normal shedding of microvillar membrane proteins as vesicles, and may stimulate a compensatory increase in microvillar membrane protein synthesis.
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PMID:Effects of enteropathogenic Escherichia coli on microvillar membrane proteins during organ culture of rabbit intestinal mucosa. 135 65

The antiprotozoal drug metronidazole, when administered orally at a dose level of 100 mg/kg body wt. daily for 7 days to rats, brought about significant elevation of renal brush-border-membrane-bound hydrolytic enzymes, such as alkaline phosphatase, maltase, sucrase, and leucine aminopeptidase (LAP). Kinetic analysis of the enzymes (substrate saturation) indicated that the drug produced an increase in the maximum of apparent initial enzyme velocity (Vmax), while the substrate affinity constant (Km) remained unaltered. These changes were not recovered to the normal level even after the drug regimen was stopped and the animals were allowed to recover for a period of 7 days. Lipid analysis of brush border membrane (BBM) revealed a significant elevation in the cholesterol, phospholipid, and ganglioside levels, while no marked change was recorded in triglyceride, free fatty acid and plasmalogen. Study of the temperature-dependent parameters of the enzymes showed that metronidazole induced a shift in the transition temperature (To) in LAP with nearly total reversibility in the recovery group. No such change was seen in the other enzymes. However, there also was a lowering in the energy of activation (Ea) below To, which returned to normal after the treatment was withdrawn.
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PMID:Changes in membrane-bound hydrolases by metronidazole in rat renal brush border. 141 Aug 3

Metronidazole (Flagyl), an antibiotic commonly used in treating intestinal infections, when administered orally at a dose level of 100 mg/kg body weight daily for 7 days to rats brought about a significant elevation of the uptake of end-product nutrients like D-glucose, L-alanine, L-aspartic acid and L-leucine in the intestinal segments. Brush border membrane-bound hydrolytic enzymes, i.e. sucrase, lactase, maltase, alkaline phosphatase and leucine aminopeptidase levels, were also elevated. Substrate kinetic analysis of the uptake of nutrients as well as the enzymes indicated that the drug increased the maximum of apparent initial velocity, while the substrate affinity constants did not change. Studies of the temperature-dependent parameters of the nutrient uptake and the enzyme activity revealed that metronidazole did not induce any shift in the transition temperature (T(o)) for the uptake but the energy of activation (Ea) was reduced in all the cases except those of maltase and leucine aminopeptidase, which registered an increase in Ea and a marginal shift in T(o), respectively. A significant elevation was seen in the levels of membrane cholesterol, phospholipid, ganglioside and plasmalogen in metronidazole-treated animals, while triglycerides and the non-esterified fatty acids remained unaffected. The effects produced by metronidazole treatment persisted in the animals, which were allowed a recovery period of 7 days after the drug regimen.
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PMID:Effect of the antiprotozoal agent metronidazole (Flagyl) on absorptive and digestive functions of the rat intestine. 147 60

Growth failure is a major complication of chronic hypoxemia, as seen in infants and children with cyanotic congenital heart disease. To determine whether chronic hypoxemia during infancy affects the gastrointestinal tract, we examined small intestinal growth and digestive enzyme activities in chronically hypoxemic newborn lambs and in age-matched controls. Chronic hypoxemia was produced by placing an inflatable occluder around the main pulmonary artery and performing a balloon atrial septostomy. Aortic oxygen saturation was reduced to 60-74% for 2 wk, after which the small intestine was removed for analysis. During chronic hypoxemia, somatic growth rate was decreased to 60% of control (hypoxemic, 135 +/- 20 versus control, 216 +/- 26 g/d, p less than 0.02). No differences in caloric intake were found (hypoxemic, 129 +/- 4 versus control, 128 +/- 4 kcal/kg/d). Chronic hypoxemia did not alter small intestinal growth, as measured by jejuno-ileal weight, jejuno-ileal length, mucosal weight, or mucosal protein or DNA contents. However, sp act of lactase, the principal disaccharidase of the infant lamb intestine, were significantly decreased (hypoxemic, 0.08 +/- 0.01 versus control, 0.146 +/- 0.03 units of enzyme activity/mg DNA, p less than 0.05), as were the total small intestinal contents of lactase (hypoxemic, 61.7 +/- 7.0 versus control, 120.6 +/- 21.7 units of enzyme activity, p less than 0.01). There also were decreases in specific and total activities of other digestive enzymes such as maltase, amino-oligopeptidase, and alkaline phosphatase in hypoxemic intestine that did not achieve statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alterations in postnatal intestinal function during chronic hypoxemia. 156 Oct 8

The common hookworm (Ancylostoma ceylanicum) infection of humans was studied in golden hamsters model system. Significant biochemical modulations were observed in hamster jejunal brush border membrane (BBM), the primary site of infection. Analysis of BBM at the peak of infection (3-weeks) revealed a marked decrease in the activities of sucrase, lactase and maltase, while activities of alkaline phosphatase, (Ca2+ + Mg2+)-ATPase and gamma-glutamyl transpeptidase were increased. Kinetic studies conducted with maltase, a superficially localised enzyme of jejunal BBM, revealed loss of enzyme active site during the infection. Among other constituents, the levels of cholesterol and triglycerides were significantly decreased with slight increase in phospholipid content in the infected animals. The hookworm infection also caused a decline in total hexose content indicating an altered membrane glycocalyx. Conversely, there was significant enhancement of hydroxyproline and sialic acid contents. SDS-PAGE analysis showed an enhancement in both low and high molecular weight proteins in jejunal BBM preparations of the infected group. Gel electrophoresis of glycoproteins further revealed the appearance of two additional peaks in the low molecular weight region and concomitant disappearance of a peak in the high molecular weight region. These results strongly support the view that the hookworm infection causes severe damage not to the site of attachment alone but also to the entire cell lining of the jejunum and therefore could influence overall digestion and absorption.
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PMID:Biochemical analysis of jejunal brush border membrane of golden hamster: pathogenic modulations due to ancylostomiasis. 159 19

Diversion of portal blood in congenital portosystemic shunts (CPSS) results in liver atrophy and passage of toxins into the systemic circulation causing hepatic encephalopathy. In some dogs, there is indirect evidence for hepatic insufficiency, but histologic findings are equivocal. This study determined whether hepatocyte integrity in PSS is comprised at a subcellular level using analytical subcellular fractionation of liver biopsies. Six dogs with CPSS had hypoproteinemia (6/6), increased serum alkaline phosphatase (6/6) and alanine aminotransferase (4/6) activity, hypocholesterolemia (6/6), and decreased blood urea (2/6). Liver biopsy specimens had increased activities (mU/mg protein) of alkaline phosphatase (17.9 +/- 10.1; controls 5.1 +/- 5.3: P less than 0.01), but not of other plasma membrane enzymes. There were increased activities of endoplasmic reticular (neutral alpha-glucosidase: 1.67 +/- 0.7; controls 0.86 +/- 0.2: P less than 0.01) and lysosomal enzymes (N-acetyl-beta-glucosaminidase: 12.6 +/- 2.3; controls 6.24 +/- 2.7: P less than 0.01; alpha-mannosidase: 0.85 +/- 0.5; controls 0.39 +/- 0.3: P less than 0.05). Subcellular fractionation on reorientating sucrose density gradients showed a high-density peak of alkaline phosphatase suggestive of a specific increase in the biliary canalicular component of enzyme activity. Neutral alpha-glucosidase was shifted to denser fractions, indicative of an increase in the proportion of rough-to-smooth endoplasmic reticulum and consistent with enhanced synthesis of membranous enzymes. There was also evidence for increased fragility of intracellular organelles, particularly lysosomes. In contrast, histology showed either no abnormalities or minor degenerative changes compatible with hepatic underperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hepatic organelle pathology in dogs with congenital portosystemic shunts. 161 98

Ten groups of calves were used to study the changes in activity levels and distribution of seven hydrolases in the intestinal mucosa during development and weaning. The calves in the first group were sacrificed at birth while those in the remaining nine groups were either milk-fed until slaughter on days 2, 7, 28, 56, 70, and 119; or weaned between days 28 and 56 and then slaughtered on days 56, 70, and 119, respectively. The small intestine was immediately cut off and divided into five segments, ie, duodenum, proximal jejunum, median jejunum, distal jejunum, and ileum. In the milk-fed animals, the activity levels of aminopeptidases A and N, alkaline phosphatase, lactase, and isomaltase were maximum at 2 days of age, and then declined sharply between days 2 and 7 but did not change significantly thereafter. By contrast, the maltase activity increased between days 7 and 119, while no sucrase activity was detected. Weaning resulted in a decrease in the activity of lactase and an increase in that of aminopeptidase N, maltase, and isomaltase. The distribution of all these enzymes along the small intestine was slightly influenced by age but not at all by weaning.
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PMID:Activity distribution of seven digestive enzymes along small intestine in calves during development and weaning. 172 29


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