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)

The development of alkaline phosphatase, maltase, and sucrase activities in the duodenum of the chick embryo was followed in organ culture in chemically defined medium; 14-day duodenum was used in most experiments, with comparisons being made with 18-day tissue. As has been previously shown for the other enzymes, sucrase activity also rises at an accelerated rate in vitro. Since chick sucrase has maltase activity, its increase appears to account for the spontaneous rise of maltase activity; the form of maltase devoid of sucrase activity seems not to be accelerated. Sucrase, sucrase-free maltase, and alkaline phosphatase are all elevated by the addition of insulin to the medium. Intestinal sucrase is well known to be responsive to hydrocortisone, but it has now been found to be unresponsive to thyroxine, except that its dissociation from the brush border is increased at hormone concentrations above 1 nM. Insulin and thyroxine act synergistically on alkaline phosphatase, but the addition of hydrocortisone diminishes the effect of the other two. With sucrase, insulin and hydrocortisone have a synergistic effect which is intensified by addition of thyroxine. The previously demonstrated influence of hydrocortisone on maltase is accounted for by the maltase activity of sucrase. In combination, however, hydrocortisone and thyroxine elevated maltase much more strongly than sucrase, and the highest maltase levels were attained when all three hormones were present.
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PMID:Chick embryo intestine in culture: influence of insulin and other hormones on sucrase, maltase, and alkaline phosphatase. 676 10

Glucagon is avidly degraded by the kidney, but the relative contribution of the luminal and basolateral tubular membranes to this process is unknown. We studied 125I-glucagon degradation by purified luminal (L) and basolateral (BL) tubular membranes prepared from rabbit kidney cortex, which showed enrichment vs. homogenate of marker enzyme activities (Na-K-ATPase for BL and maltase for L) of 10- and 14-fold, respectively. Renal homogenates and both tubular membrane fractions degraded glucagon avidly without reaching saturation even at pharmacologic concentration (10(-5) M) of the hormone. At physiologic concentration (3 x 10(-11) M) BL membranes degraded substantial amounts of glucagon (8.1 +/- 0.9 pg . micrograms protein-1 . h-1) even though at lesser rates (P less than 0.001) than the luminal fraction (33.3 +/- 1.9 pg . micrograms protein-1 . h-1). Competition experiments suggested that glucagon-degrading activity in both fractions includes both specific and nonspecific components, and the potency of different enzyme inhibitors to decelerate glucagon degradation was strikingly similar in the two membrane preparations. Glucagon degradation differed in several important aspects from the manner in which tubular membranes catabolize insulin, including absolute degradation rates and relative degrading capacity of the membranes vs. homogenates, both being substantially higher for glucagon. These results provide direct evidence that the renal metabolism of glucagon also involves its degradation by peritubular cell membranes.
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PMID:Glucagon degradation by luminal and basolateral rabbit tubular membranes. 682 62

Spontaneously diabetic non-obese mice of the ICR strain were newly inbred in Shionogi laboratory, Japan. Animals became diabetic suddenly, more frequently and severely in females. Blood glucose levels were 452 +/- 73 mg/100 ml with serum insulin levels of less than 1.0 microU/ml in the fed state. Parabiosis with normal control ICR mice for 2 weeks decreased the blood glucose level to 260 +/- 51 mg/100 ml (P less than 0.01) and resulted in serum insulin levels of 46.0 +/- 18.0 microU/ml (P less than 0.01). Kidney homogenate beta-N-acetylglucosaminidase and beta-galactosidase activities were reduced in diabetic mice (42% and 44% decreases respectively) (P less than 0.025 and P less than 0.001), and restored almost to normal after 2 weeks of parabiosis. Renal alpha-mannosidase activity was decreased 43% (P less than 0.001) in the diabetic mice but unaffected by parabiosis. Serum beta-N-acetylglucosaminidase, beta-galactosidase and alpha-glucosidase activities were significantly increased in diabetic mice (179%; 233% and 58% increase respectively) (P less than 0.005, P less than 0.001 and P less than 0.001), and returned to normal with parabiosis.
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PMID:The effects of parabiosis on serum and kidney glycosidase activities in spontaneously diabetic mice. 699 68

Fifty-gram carbohydrate tolerance tests were performed on healthy volunteers to test the activity and specificity of an alpha-glucoside hydrolase inhibitor, acarbose (BAY g 5421). Two hundred milligrams acarbose reduced the area under the blood glucose response curve by 89% (P less than 0.001) after sucrose by 80% (P less than 0.002) after starch, by 19% (N.S.) after maltose, with no effect on glucose. Breath hydrogen measurements indicated an almost complete malabsorption of the sucrose. At 50 mg acarbose, some reduction in blood glucose and insulin response to sucrose was still seen, but no significant hydrogen production. It is suggested that at lower doses, acarbose may prolong the time course over which carbohydrate is absorbed as does dietary fiber; as with fiber, it may be a useful adjunct to diabetic therapy.
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PMID:Scope and specificity of acarbose in slowing carbohydrate absorption in man. 702 48

Acarbose, an alpha-glucosidase inhibitor, delays starch digestion and inhibits intestinal sucrase and maltase activity. Twenty-eight insulin dependent diabetics were given Acarbose (3 x 100 mg daily) over a two month period, preceded and followed by a two month placebo period. Acarbose reduced post-breakfast and post-dinner blood glucose values by 25% (p less than 0.001) and 24% (p less than 0.05) respectively. It also significantly reduced mean daily blood glucose by 18% (p less than 0.05) and mean amplitude of glycaemic excursions from 8.0 +/- 0.6 to 5.5 +/- 0.4 mmol/l (p less than 0.0005). Weight did not change significantly. Daily caloric and carbohydrate intake remained constant throughout the study while insulin requirements decreased slightly but significantly. Out of the 28 patients, 18 had absent while ten had slight residual B cell function as assessed by plasma C-peptide measurements. Treatment with Acarbose did not significantly affect residual B cell function. The beneficial effect of Acarbose on blood glucose control was seen in patients both with and without residual B cell secretion. The major side-effect was flatulence which was never severe enough to interrupt treatment, but led to a 50% reduction of the dose in one patient. It is concluded that Acarbose represents a useful additional means of improving metabolic control in insulin dependent diabetics.
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PMID:Improvement of metabolic control in insulin dependent diabetics treated with the alpha-glucosidase inhibitor acarbose for two months. 702 58

Certain effects of insulin administration on newborn rat hepatocytes were studied using biochemical assays, electron microscopy and quantitative morphometry. Insulin produced an inhibition of postnatal hyaloplasmic glycogen breakdown, of lysosomal glycogen breakdown and of the development of the Golgi apparatus. The insulin-treated animals showed a low activity of the enzyme, acid alpha 1,4-glucosidase (maltase). The results support the postulate that the catabolism of lysosomal glycogen is controlled by those agents that regulate the catabolism of hyaloplasmic glycogen (Am. J. Path., 63: 1-17 and Am. J. Path., 63: 23-36, 1971). Control could be mediated through changes in the activity of the lysosomal acid alpha 1,4-glucosidase.
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PMID:An electron microscopic and biochemical study of the effects of insulin on newborn rat hepatocytes. 703 26

Insulin influences certain metabolic and transport renal functions and is avidly degraded by the kidney, but the relative contribution of the luminal and basolateral tubular membranes to these events remains controversial. We studied (125)I-insulin degradation [TCA and immunoprecipitation (IP) methods] and the specific binding of the hormone by purified luminal (L) and basolateral (BL) tubular membranes. These were prepared from rabbit kidney cortical homogenates by differential and gradient centrifugation and ionic precipitation steps in sequence, which resulted in enrichment vs. homogenate of marker enzymes' activities (sodium-potassium-activated adenosine triphosphatase for BL and maltase for L) of 8- and 12-fold, respectively. Both fractions degraded insulin avidly and bound the hormone specifically without saturation even at pharmacologic concentrations (10 muM). At physiologic insulin concentrations (0.157 nM) BL membranes degraded substantial amounts of insulin (44.2+/-2.6 and 40.7+/-2.2 pg/mg protein per min by the TCA and IP methods, respectively), even though at lesser rates (P < 0.001) than the luminal fraction (67.2+/-2.3 and 75+/-6.2 pg/mg protein per min, respectively); the rate of insulin catabolism by BL membranes was significantly higher (P < 0.001) than that which could be attributed to their contamination by luminal components [12.2+/-1.9 pg/mg per min (TCA method), or 13.7+/-1.9 pg/mg per min (IP method)]. Competition experiments suggested that insulin-degrading activity in both fractions includes both specific and nonspecific components. In contrast to degradation, insulin binding by both membranes was highly specific for native insulin and was severalfold higher in BL than L membranes [17.5+/-1.3 vs. 4.5+/-0.4 fmol/mg protein (P < 0.001) at physiologic insulin concentrations]. Despite the marked difference in the binding capacity for insulin by the two membranes, the patterns of labeled insulin displacement by increasing amounts of unlabeled hormone were superimposable (50% displacement required approximately 3 nM), suggesting that their receptors' affinity for insulin was similar. These observations provide direct evidence that interaction of insulin with the kidney involves binding and degradation of the hormone at the peritubular cell membrane.
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PMID:Insulin binding and degradation by luminal and basolateral tubular membranes from rabbit kidney. 704 Apr 74

Inhibition of carbohydrate digestion by the alpha-glucosidase inhibitor acarbose (BAY g 5421)reduces carbohydrate-induced postprandial blood glucose increase and insulin secretion. As a consequence, in feeding experiments sucrose-induced hyperinsulinemia and hypertriglyceridemia in genetically obese (fa,fa) "Zucker" rats were dose-dependently reduced by addition of acarbose to the diet (15-80 mg/100 g feed). The body weight gain was dose-dependently reduced. In short-term experiments with a fat-free diet acarbose not only prevented serum triglyceride and free fatty acid increase in spite of lowered insulin concentrations but also decreased their concentrations below the values obtained on standard feed. Under these conditions there were no significant effects on body weight. Hypertriglyceridemia induced by i.v. injection of the lipoprotein lipase inhibitor Triton WR 1339 was reduced without affecting body weight in "Zucker" rats after 3 days on a fat-free diet supplemented with acarbose. The triglyceride increase was even lower than in animals kept on standard feed. The data demonstrate that acarbose reduces sucrose-induced hypertriglyceridemia in (fa,fa) "Zucker" rats by diminishing VLDL production and/or secretion rather than by increasing VLDL removal from the blood.
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PMID:Reduction of carbohydrate-induced hypertriglyceridemia in (fa,fa) "Zucker" rats by the alpha-glucosidase inhibitor acarbose (BAY g 5421). 704 75

The influence of metronidazole on the breath hydrogen response and symptoms of sucrose malabsorption was investigated in a double-blind, randomized and controlled study. Carbohydrate malabsorption was induced by the competitive alpha-glucosidase inhibitor, acarbose. Metronidazole reduced flatulence and the breath hydrogen response during sucrose malabsorption without a change in intestinal carbohydrate absorption, as indicated by serum levels of gastric inhibitory polypeptide, serum insulin and blood glucose. The effect of metronidazole suggests that anaerobic bacteria mediate both signs and symptoms of the colonic response to sucrose malabsorption. In contrast to previous reports on lactose malabsorption, it was not possible to quantify sucrose malabsorption by comparing the breath hydrogen response to sucrose malabsorption with the H2 response to a lactulose load.
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PMID:Influence of metronidazole on the breath hydrogen response and symptoms in acarbose-induced malabsorption of sucrose. 716 May 49

The alpha-glucosidase specific for the hydroxylysine-linked disaccharide units of collagens (or 2-0-alpha-D-glucopyranosyl-5-0-beta-D-galactopyranosylhydroxy-L-lysine glucohydrolase) has been measured in kidney cortex and brain cortical tissue of streptozotocin diabetic rats after 19, 23 or 28 weeks of diabetes and of aged rats 22 months old. Increased specific activities of the enzyme have been found repeatedly in the dialyzed homogenates and the 7.2 X 10(6) g.min supernatants of kidney and brain at the various stages of diabetes when compared with age-matched controls; the specific activities returned to a normal level after insulin treatment. Similar increased specific activities were observed in kidney and brain of the aged normoglycemic rats when compared with young adult rats. In diabetic kidney cortex, beta-galactosidase and p-nitrophenyl-alpha-D-glucoside glucosidase specific activities were decreased in contrast to the increase of glucosyl-galactosyl-hydroxy-lysine glucohydrolase. In kidney cortex of the aged rats, beta-galactosidase activity was also decreased, but p-nitrophenyl-alpha-D-glucoside glucosidase was increased. In both diabetic and aged rats, thickening of the kidney glomerular basement membranes was confirmed; thickening of the brain cortical capillary basement membranes was also observed. Thus in the diabetic and aged animals, the increased glucosyl-galactosyl-hydroxylysine glucohydrolase specific activity was associated with basement membrane thickening in the kidney and the brain.
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PMID:Studies on the alpha-glucosidase specific for collagen disaccharide units: variations associated with capillary basement membrane thickening in kidney and brain of diabetic and aged rats. 716 52


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