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)

One membrane-bound alpha-glucosidase and two soluble alpha-glucosidases were isolated from homogenates of the hind-midgut, the main digestive region in Musca domestica larvae. The membrane-bound alpha-glucosidase and the low-Mr soluble alpha-glucosidase hydrolyze maltopentaose better than maltose, maltotriose, and maltotetraose, the reverse being true for the high-Mr soluble alpha-glucosidase. A membrane-bound glucoamylase previously described in Musca domestica midgut was shown by gradient centrifugation and dialysis against EDTA to result from the combined action of an amylase and an alpha-glucosidase. The determination of amylase, alpha-glucosidases, soluble and membrane-bound carboxypeptidase A, membrane-bound aminopeptidase and dipeptidase along the tissue and luminal contents of the hind-midgut is described. The data support a proposal concerned with how starch and protein are digested in Musca domestica larval hind-midguts and where and how midgut glycosidases and peptidases are secreted.
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PMID:Regional distribution and substrate specificity of digestive enzymes involved in terminal digestion in Musca domestica hind-midguts. 180 31

The regulatory effect of epidermal growth factor (EGF) on the developmental pattern of brush border hydrolases was studied in the proximal jejunum and colon of the newborn rat. In the proximal colon, daily administration of EGF for 1, 3, or 5 days postpartum inhibited the postnatal increase in lactase, maltase, and aminopeptidase specific activities. In contrast, in the jejunum EGF did not influence lactase activity, inconsistently increased maltase activity, and partly prevented the early postnatal decrease in aminopeptidase activity. In the proximal colon, EGF showed additive effects with T4 and hydrocortisone on the inhibition of lactase activity. In the jejunum, EGF potentiated the effect of hydrocortisone and T4 on the expression of sucrase activity and had only a slight effect when injected alone. The incorporation rate of [3H]thymidine in the proximal colon and jejunum was not different in control and treated rats, indicating the absence of an effect of EGF on DNA synthesis. These results show that EGF may play an important physiological role in the enzymatic differentiation of the developing intestine during early postnatal development. Alone or acting with T4 or glucocorticoids, EGF may induce the decline of digestive hydrolases in the proximal colon. In the small intestine EGF may play a major role in the triggering of sucrase expression.
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PMID:Effect of epidermal growth factor on the expression of digestive hydrolases in the jejunum and colon of newborn rats. 211 92

To further document the effect of insulin on intestinal maturation, suckling rats were treated either with exogenous insulin (12.5 mU.g body wt, intraperitoneally, twice daily) or with saline from d 8 to 12 postpartum. Sucrase activity in brush border membrane extracts was precociously induced by insulin, whereas the activities of other brush border membrane enzymes (maltase, aminopeptidase, and neutral lactase) were enhanced (+ 30 to + 131%, p less than 0.01 versus controls). The lysosomal enzyme, N-acetyl-beta-glucosaminidase, which normally declines at weaning was significantly (p less than 0.025) decreased in both villus (-51%) and crypt cells (-57%) isolated from the jejunum of insulin-treated rats. The microsomal enzyme, sulfatase C, and the cytosolic enzyme, lactate dehydrogenase, were also sensitive to insulin with decreases in activity ranging from -37 to -63% (p less than 0.05) compared to saline-treated control rats. Insulin at doses of 0.5 or 12.5 mU did not influence plasma total corticosterone levels, which were about 9-fold lower in suckling than in 25-d-old weaned rats. In weaned rats (from d 25 to 32) insulin treatment (12.5 mU) failed to influence the activity of brush border membrane hydrolases or of lysosomal, microsomal, and cytosolic enzymes. The synthesis rate of mature sucrase-isomaltase, measured in weaned rats (32 d) by the incorporation of 14C-leucine into the enzyme precursor protein, was equivalent in both groups. These data demonstrate that the immature enterocyte of the suckling rat is responsive to insulin, whereas the mature enterocyte of the weaned rat is unresponsive.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hormonal regulation of the rat small intestine: responsiveness of villus and crypt cells to insulin during the suckling period and unresponsiveness after weaning. 217 34

Transport of nutrients and kinetic parameters (Vmax and Km) of brush border membrane (BBM) enzymes were studied in duodenum, jejunum, and ileum from atherogenic diet-fed monkeys. The Km remained unaltered while feeding of atherogenic diet resulted in higher Vmax of sucrase, maltase, and alkaline phosphatase and lower Vmax of gamma-glutamyltranspeptidase and leucine-aminopeptidase compared to controls. Na+-dependent D-glucose transport was higher in duodenum and jejunum and unaltered in ileum. In contrast to D-glucose transport, the transport of amino acids was decreased in all three intestinal segments from atherogenic diet-fed monkeys.
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PMID:Effects on intestinal nutrient uptake and brush border membrane enzymes in response to atherogenic diet in rhesus monkeys. 257 71

The effects of starvation (72 h) and refeeding with three liquid diets, differing only in the molecular form of the nitrogen source (whole whey proteins, WP; tryptic whey protein hydrolysate, WPH; and amino acid mixture, AAM), on the jejunal mucosal morphology and brush border enzyme activities (sucrase, S; maltase, M; and neutral aminopeptidase, NA) of male Wistar rats were studied. All three diets produced repair of the fasting-induced mucosal atrophy; the WP diet gave the most rapid growth with maximum villus height (VH) and protein content after 48 h (p less than 0.01). AAM gave the fastest and greatest stimulation of sucrase and maltase activities (p less than 0.01). There were no significant differences in NA activity. In control rats the WPH and AAM diets produced significantly greater villus height and disaccharidase activities than did the WP diet. Jejunal morphology and disaccharidase activities can be modified by the molecular form of alimentary protein and nutritional status interferes with these modifications.
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PMID:Dietary whey proteins and their peptides or amino acids: effects on the jejunal mucosa of starved rats. 264 93

Juvenile white sturgeon were fed isonitrogenous diets containing 27.2% glucose, fructose, maltose, sucrose, lactose, dextrin, raw corn starch or cellulose for 8 wk. Growth, body composition, plasma chemistry (with the exception of glucose), and liver glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49), malic enzyme (EC 1.1.1.40) and isocitrate dehydrogenase (ICDH, 1.1.1.42) activities of sturgeon were significantly (P less than 0.05) affected by the different dietary carbohydrate sources. Sturgeon fed either the maltose or glucose diets had the highest percent energy retained, followed by those fed either the dextrin, raw corn starch or sucrose diets, whereas those fed either the lactose, fructose or cellulose diets had the lowest. Sturgeon fed either the maltose or glucose diets were hyperlipidemic, having twice the amount of plasma total lipid, triacylglycerol and total cholesterol as fish fed the other carbohydrate sources. These two carbohydrate sources were also more lipogenic: maltose- or glucose-fed sturgeon had significantly higher body lipid and liver G6PDH, malic enzyme, and ICDH activities. The poor ability of sturgeon to utilize either sucrose or lactose appears to be due to low intestinal sucrase (EC 3.2.1.48) and lactase (EC 3.2.1.108) activities. Intestinal aminopeptidase (EC 3.4.11.11), maltase (EC 3.2.1.20), sucrase and lactase activities of sturgeon were not affected by feeding different carbohydrate sources for 8 wk.
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PMID:Ability of juvenile white sturgeon (Acipenser transmontanus) to utilize different carbohydrate sources. 272 21

We report the relative frequency of sucrase-isomaltase (SI) antigen expression in human colonic adenocarcinoma (22/57), in peritumoral mucosa taken next to the tumor (31/41) or distant from it (29/42) as well as in 21/23 polyps. Our results are based on indirect immunofluorescence with a monoclonal antibody (MAb) specific for human intestinal SI. A regular and intense expression of SI occurred only in 6 tumor specimens. In the remaining 16 SI-positive tumor samples, labelling was heterogeneous, i.e., scattered over more or less extensive areas. A similar irregular staining pattern was also found in polyps and in peritumoral mucosa, irrespective of its distance from the tumor. Electron microscopic examination of 19 carcinomas mostly revealed altered brush-border membrane features, irrespective of histological SI staining pattern. Brush-border enzyme activities of sucrase, alkaline phosphatase and maltase showed no difference between tumor specimens and peritumoral mucosa, but aminopeptidase was depressed in the former. Sucrase activity was extremely low (mean values 1.1 to 1.8 mU/mg protein) and rose only exceptionally to 17.5 mU/mg prot.
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PMID:Sucrase-isomaltase expression and enterocytic ultrastructure of human colorectal tumors. 275 30

Kinetic parameters (Km and Vmax) of renal brush border membrane (BBM) enzymes alkaline phosphatase, maltase, leucine-aminopeptidase and gamma-glutamyltranspeptidase were used as markers for the early detection of pyelonephritis. Km of all the enzymes studied remained unaltered. The Vmax of all the enzymes studied were found to be significantly decreased (p less than 0.05) 3 or 4 days postinfection and onwards in the left obstructed kidney. The Vmax of alkaline phosphatase and leucine-aminopeptidase was found to be significantly increased (p less than 0.05) in early stages and decreased (p less than 0.05) in later stages of infection in the right unobstructed kidney. No histopathological lesions confirming pyelonephritis could be seen 7 days postinfection in the left kidney and right kidney remained histopathologically unaltered. This demonstrated that BBM enzymes are much earlier disturbed as compared to histopathological changes.
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PMID:New sensitive markers for the detection of experimental ascending pyelonephritis. 288 3

The ability of adapting ileal enterocytes to express different digestive enzymes in their brush border membranes was tested in young female Wistar rats (n = 72) receiving 60% proximal small bowel resection. In control rats with intestinal transection both neutral aminopeptidase and alpha-glucosidase activities were shown, by quantitative cytochemistry, to increase during enterocyte migration over the lower part of the villus; thereafter enzyme activities declined or remained approximately constant. Proximal enterectomy increased the amount of alpha-glucosidase but not neutral aminopeptidase activity appearing during early enterocyte development. Thymidine labelled autoradiography showed that the rate of enterocyte migration along the ileal villus nearly doubled after jejunal resection (19.3 v 11.1 microns/h). Nevertheless, the time taken for both peptidase and saccharidase activities to appear at maximal rates in the brush border membrane was diminished by about five hours. Thus ileal enterocytes adapt to proximal small bowel resection by selective increments in enzyme expression, findings that contradict the previous hypothesis of simple metabolic immaturity.
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PMID:Increased activity of digestive enzymes in ileal enterocytes adapting to proximal small bowel resection. 288 50

The effects on glomerular and proximal tubular function of an ionic contrast agent (sodium meglumine diatrizoate) and a nonionic agent (iopamidol) were compared in 34 patients with normal renal function. The patients received large doses (2.5 ml/kg body weight) of contrast material for IV digital subtraction angiography. Urine samples, collected before, immediately after, and on the first and third days after digital subtraction angiography, were analyzed for albumin, alanil-aminopeptidase, alpha-glucosidase, and beta-2-microglobulin. The changes noted were mild and of short duration with both contrast agents, despite the high dose given. These results suggest that, at least as far as renal toxicity is measured by these tests is concerned, ionic monomers can be safely used instead of more expensive nonionic media in procedures, such as digital subtraction angiography, that require high doses of contrast material.
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PMID:Contrast agent nephrotoxicity: comparison of ionic and nonionic contrast agents. 289 Dec 85


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