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)

Analytical subcellular fractionation techniques using metrizamide density gradients have been used to investigate the properties of the gut hormone storage granules and the principal organelles from homogenates of normal human jejunal mucosa obtained by peroral mucosal biopsy. The individual hormones, detected by radioimmunoassay, each showed single discrete peaks in the density gradient experiments indicating localisation to single granules each with characteristic modal densities. Thus motilin showed a modal density of 1.15, gastrin 1.16, gastric inhibitory polypeptide (GIP) 1.17, enteroglucagon 1.18 and somatostatin and vasoactive intestinal peptide (VIP) 1.10 g/ml. The following organelles, characterised by their marker enzymes were located in the density gradients; plasma membrane (5'-nucleotidase) brush border (alpha-glucosidase, pH 6.0) mitochondria (particulate malate dehydrogenase), peroxisomes (catalase), lysosomes (N-acetyl-beta-glucosaminidase), endoplasmic reticulum (alpha-glucosidase, pH 8.0), cytosol (lactate dehydrogenase). These studies provide biochemical evidence of the distinct nature of the individual gut hormone storage granules and provide a basis for studying dynamic changes in the granules in response to physiological stimuli and pathological processes.
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PMID:Characterisation of gut hormone storage granules from normal human jejunum using metrizamide density gradients. 730 92

The present study examined the effects of dexamethasone on mucosal adaptation after massive small bowel resection. Rats underwent 80% jejunoileal resection or a sham operation and received either vehicle or 128 micrograms.kg-1.day-1 sc dexamethasone for 7 days. Dexamethasone infusion resulted in decreased weight, DNA content, and protein content in the duodenojejunal and ileal mucosa in both sham and resected rats. Sucrase, lactase, and maltase activities (all in mumol.g protein-1.min-1) in the duodenojejunal mucosa were elevated by dexamethasone infusion. By contrast, enzyme activities were elevated only in the ileal mucosa of dexamethasone-infused sham-operated rats compared with sham-operated control rats, and dexamethasone did not elevate enzyme activities in resected rats. We further examined whether the inhibitory effects of dexamethasone on mucosal adaptation may be related to changes in either insulin-like growth factor (IGF) or IGF binding protein (BP) serum levels. Serum IGF-I and IGF-II levels were markedly decreased in dexamethasone-infused resected and sham-operated rats. IGF BP-1 serum levels were elevated by dexamethasone treatment with a concomitant depression in serum IGF BP-2 levels. IGF BP-3 levels were lowered by dexamethasone treatment in sham-operated rats and by gut resection, and serum IGF BP-4 levels did not change. These results suggest that the growth-inhibiting effects of dexamethasone in small intestinal mucosa may be partially mediated by decreased serum IGF levels or by alterations in IGF activity associated with changes in serum levels of IGF BPs.
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PMID:Dexamethasone inhibits mucosal adaptation after small bowel resection. 751 28

The only new pharmaceutical therapy for Type 2 (non-insulin-dependent) diabetes that has become available for clinical use in the last 40 years is the alpha-glucosidase inhibitor, acarbose, which reduces postprandial glucose levels by retarding digestion of complex carbohydrates in the gut. It has proved difficult to find other new metabolically active drugs that lack toxicity. Agents that reduce insulin resistance include the thiazolidinediones, which are very effective in animals. Of these, the only one that has been maintained in clinical evaluation appears from preliminary data to have an effect that although still useful, is not greater than that reported for current oral agents. Agents that reduce non-esterified fatty acid levels by inhibiting lipolysis, thereby allowing increased peripheral uptake of glucose, have so far given minimal reduction in glycaemia. The development of fatty acid oxidation inhibitors to reduce gluconeogenesis in the liver has been hampered by toxicity, but additional new agents are being studied. The most promising new approach for enhancing insulin secretion has been suggested by the demonstration that pharmacological doses of GLP-1 (7-36 amide), a natural enteric incretin hormone, improves pancreatic beta-cell and alpha-cell sensitivity to glucose and can induce normal basal glucose levels in diabetic man. The future development of GLP-1 agonists will be of great interest. This is timely as other insulin secretogogues, such as alpha 2 adrenergic blockers have proved relatively ineffective. Anti-obesity agents would in theory be beneficial, but have either had limited efficacy or have been avoided because of concern about long-term safety. Until new pharmaceutical agents become available, if near-normal glycaemia is to be achieved, many more Type 2 diabetic patients will need insulin therapy. When full insulin replacement therapy is not feasible, reducing the fasting blood glucose level towards normal with a single daily basal insulin supplement, either alone or in combination with oral agents, could become a more widely used therapy.
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PMID:Drugs on the horizon for treatment of type 2 diabetes. 764 18

Acarbose is an alpha-glucosidase inhibitor proposed for the treatment of diabetic patients. It acts by competitively inhibiting the alpha-glucosidases in the intestinal brush border. The principal action of these enzymes is to convert nonabsorbable dietary starch and sucrose into absorbable monosaccharides (e.g. glucose). Enzyme inhibitors delay this conversion, slowing the formation and consequently the absorption of monosaccharides, and thus reducing the concentration of postprandial blood glucose. Both starch and sucrose are influenced, whereas lactose and glucose are not. Many studies in experimental animals, healthy volunteers and patients with non-insulin-dependent diabetes mellitus (NIDDM) have shown that acarbose decreases postprandial blood glucose, with a lesser reduction of fasting blood glucose, plasma triglycerides and postprandial insulin levels. In long term studies in NIDDM patients, acarbose significantly reduced glycosylated haemoglobin levels. Acarbose is only minimally absorbed from the gut and no systemic adverse effects have been demonstrated after long term administration. The drug allows undigested carbohydrates to pass into the large bowel where they are fermented causing flatulence, bloating and diarrhoea. These symptoms, which occur in approximately 30 to 60% of patients, tend to decrease with time and seem to be dose-dependent. They are minimised by starting therapy with low doses (such as 50mg 3 times daily) which may be effective in many patients. An increase in serum hepatic transaminases observed in earlier studies in the US, where doses of acarbose up to 900mg daily were used, has been not reported with the lower doses of the drug actually recommended [150 to 300mg (up to 600mg) daily]. In conclusion, acarbose may be useful in patients with NIDDM when diet alone is no longer able to maintain satisfactory blood glucose control. Furthermore, it may be a valid alternative to sulphonylurea or biguanide therapy when these drugs are contraindicated and insulin administration may be delayed. Acarbose seems also to be a useful adjunct to hypoglycaemic oral agents but its precise role in this field has not been fully clarified.
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PMID:A risk-benefit appraisal of acarbose in the management of non-insulin-dependent diabetes mellitus. 772 53

Since epidermal growth factor (EGF) enhances gut mucosal regeneration, the present study was undertaken to evaluate the effect of EGF on brush-border membrane enzyme activity and glutamine uptake in the intestinal remnant following extensive small bowel resection. Twenty-four adult male New Zealand White rabbits were divided into three groups: Group 1 (n = 12) served as controls. Groups 2 and 3 (n = 6 each) underwent a 50-60% mid-jejunoileal resection with anastomosis of the remaining intestine, leaving 90 cm between the pylorus and the ileocecal valve. Group 3 rabbits had a subcutaneous osmotic pump implanted to deliver EGF for 7 days at 0.3 micrograms/kg/hr. Rabbits from Groups 2 and 3 were sacrificed 3 weeks postoperation. Mucosa from the proximal and distal segments of the remaining intestine was analyzed for wet/dry weight, maltase and aminooligopeptidase activity, and glutamine uptake. There was a twofold increase in mucosal dry weight/cm of intestine in rabbits without EGF at 3 weeks (Group 2) and a fourfold increase in those given EGF (Group 3). The maltase enzyme capacity (UEnzyme/rabbit) increased from 37 +/- 10 in controls (Group 1) to 167 +/- 30 without EGF and 207 +/- 30 with EGF. The aminooligopeptidase enzyme capacity (UEnzyme/rabbit) increased from 55 +/- 10 to 147 +/- 20 and 226 +/- 30 in Groups 1, 2, and 3, respectively. Glutamine uptake capacity (microM glutamine/min) also increased significantly, from 63 +/- 19 in Group 1 to 88 +/- 6 without EGF and 162 +/- 18 with EGF (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effect of epidermal growth factor on mucosal function after ileal resection. 779 29

The present paper addresses the question how alpha-glucosidase inhibitors affect glucose homeostasis. To facilitate this already established data on the effects of induced malabsorption on gut hormones such as gastric inhibitory polypeptide (GIP) in connection with preliminary findings which deal with the new incretin hormone glucagon-like peptide 1 (7-36) amide (GLP-1) are discussed. To emphasize the possibly important impact of a regulated GLP-1 release in response to glucosidase inhibitor treatment we evaluate the recently introduced concept of 'glucose competence' of pancreatic beta-cells. The slowing of nutrient (i.e. glucose) absorption by therapeutic means (for example, acarbose) could supplement a new approach in the treatment of type 2 diabetics which would utilize the well-preserved insulinotropic activity of GLP-1 in these patients, its glucagon-lowering effect, and its possible inhibition of gastric emptying rates, the latter helping to reduce the requirement for rapid insulin secretory responses as is intended while using alpha-glucosidase inhibitor treatment.
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PMID:Intestinal effects of alpha-glucosidase inhibitors: absorption of nutrients and enterohormonal changes. 800 23

The proliferative activity of gut mucosa is altered with aging; the potential for the aged gut to respond to trophic stimuli is not known. The purpose of this study was to determine whether there are age-related differences in the effects of the trophic gut peptide neurotensin (NT) on the structure and function of small bowel mucosa. NT (300 micrograms/kg) or saline (control) was injected subcutaneously at 8-h intervals for 5 days in rats of two age groups, young (2 mo) and aged (24 mo). On day 6, rats were killed, and the gut mucosa (proximal and distal small bowel) was scraped, weighed, and analyzed for DNA, RNA, and protein content and for disaccharidase (sucrase and maltase) activity. In a second experiment, the groups of rats and the protocol for NT administration were identical; however, when the rats were killed, the distal gut was removed for histological evaluation of crypt and villus length (mm) and density (no./cm gut segment) and bromodeoxyuridine immunohistochemistry. NT produced significant increases in mucosal growth (wt, DNA, RNA, and protein) in both age groups when compared with age-matched controls; the increase of growth measurements was the greatest in the small bowel mucosa of the aged rats. In addition, NT increased crypt density in both groups; only the aged group treated with NT demonstrated increases in crypt depth and villus height. Specific activities of sucrase and maltase did not change with NT treatment in either of the age groups. We conclude that the proliferative potential of small bowel mucosa is maintained with aging in response to administration of NT.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of aging on neurotensin-stimulated growth of rat small intestine. 807 18

The effect of eight anthelmintics (Rintal, Fenbesan, Telmin, Banminth, Pyrantel, Nilverm, Levamisol and Bioscardina) on the alpha- and gamma-amylases, trypsin, and lipase from pig's pancreas and gut of Ascaris suum was determined. In extracts from A. suum gut also the maltase, trehalase and saccharose activities were examined. All drugs tested did not influence on the host's alpha-amylase. Telmin and Bioscardina were inhibitors of gamma-amylase, Rintal and Telmin--of trypsin, Fenbesan and Bioscardina--of lipase from pig's pancreas. Among the parasite's enzymes the lipase was the most sensitive. Its activity was decreased (35-60%) by Telmin, Nilverm and both pyrantel derivatives. The activity of maltase and trehalase was reduced by Levamisole and Banminth, that of saccharose by Levamisole. It is concluded that the anthelmintics Levamisole and Banminth seemed the most efficient among the tested drugs because they did not alter the activity of host's enzymes and, showed the inhibitory effect on three of parasite's enzymes.
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PMID:[In vitro study of anthelmintic influence on activities of digestive enzymes in extracts from the gut of Ascaris suum and pig's pancreas]. 812 27

This paper reviews the effects of renal insufficiency on the pharmacokinetics of oral antidiabetic drugs. Of the 3 groups of drugs currently available for the treatment of non-insulin-dependent diabetes mellitus (NIDDM), the sulphonylureas and metformin are, in general, well-tolerated and generally safe. In patients with chronic renal insufficiency, however, care must be exercised in the use of many of these drugs, as accumulation, either of the active drug or of active metabolites, can lead to serious adverse effects such as hypoglycaemia or, with metformin, lactic acidosis. The sulphonylurea drugs, to a greater or lesser degree, are metabolised in the liver to a variety of active or inactive compounds which, in general, are excreted by the kidneys. In addition, varying amounts of parent compound may depend on renal elimination. As a result, sulphonylurea drugs such as tolazamide, acetohexamide, chlorpropamide and glibenclamide (glyburide) are more likely to cause significant hypoglycaemia, as the metabolism of these drugs, compared with other commonly prescribed sulphonylureas, can lead to the accumulation of either the parent drug or the active metabolite in the presence of renal insufficiency. Tolbutamide, glipizide, gliclazide and gliquidone are much less likely to cause hypoglycaemia as their metabolites are either inactive or have minimal hypoglycaemic potency. Metformin is dependent on renal excretion and is not significantly metabolised. As a result, caution is required when treating patients with renal insufficiency where metformin accumulation can occur, with the danger of lactic acidosis. Although the correlation between creatinine clearance (CLCR) and total oral clearance of drug is weaker than the correlation between CLCR and renal clearance (CLR) of metformin, it is clear that renal insufficiency is associated with most cases of metformin-induced lactic acidosis. For this reason, clinicians in general would regard a raised plasma creatinine as a contraindication to metformin treatment. Acarbose, an alpha-glucosidase inhibitor, and a relatively new agent for treating NIDDM, is likely to be safe in patients with impaired renal function, as the drug is not significantly absorbed from the gut, but data on this subject are lacking.
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PMID:Pharmacokinetics of oral antihyperglycaemic agents in patients with renal insufficiency. 885 33

Gut ischemia has been implicated in the pathogenesis of necrotizing enterocolitis. Cyclosporine A and rapamycin, both potent novel immunosuppressants which act on signal transduction pathways in CD4+ T-cells, could potentially modulate immune/inflammatory cellular reactions involved in tissue ischemia/reperfusion injury. We hypothesized that cyclosporine A and rapamycin would preserve mucosal cell function and attenuate inflammatory T-cell-mediated cellular changes associated with small bowel ischemic injury. Forty Sprague-Dawley rats underwent 60 min of gut ischemia by vascular occlusion of the superior mesenteric vessels. Animals were randomized to four groups (n = 10): cyclosporine A (CSA, 5 mg/kg/day SQ), rapamycin (RAP, 2 mg/kg/day SQ), cyclosporine A and rapamycin (C&R), and vehicle given to controls (CON). Following 1 hr of reperfusion, small bowel was harvested for xanthine oxidase (XO, units/mg protein) and maltase (MALT, mM substrate degraded/min/g protein) assays. Blood was obtained from the portal vein for tumor necrosis factor-alpha (TNF-alpha, pg/ml) assay. The results of the study are presented below (mean +/- SEM, *, P < 0.05 versus controls). (Table in text) The results indicate that cyclosporine and rapamycin each play a significant role in attenuating ischemia/reperfusion injury in the gut. These data suggest that there are cytoprotective and anti-inflammatory mechanisms of these drugs independent of T-cell signal transduction that provide some protective effect in small bowel ischemia. Furthermore, T-cell-mediated immune mechanisms may not be associated with the adverse effects of small bowel ischemia/reperfusion injury. Additional investigation will be necessary in order to define the role of T-cell-mediated immune injury in the gut and how this relates to the beneficial effect of immunosuppression in small bowel mucosal ischemic injury.
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PMID:Beneficial effects of cyclosporine and rapamycin in small bowel ischemic injury. 890 56


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