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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimentally induced diabetes enhances the specific activity of several microvillus membrane proteins in the rat small intestine. The increase in the specific activity of sucrase-isomaltase has been shown by others to be due to an increase in enzyme protein, raising the possibility that diabetes induces a generalized increase in microvillus membrane proteins. Since intramembrane particles (IMPs) seen on freeze-fracture replicas of microvillus membranes are thought to represent integral membrane proteins, we compared microvillus IMP densities in diabetic rats with those in control rats. In addition, mucosal sucrase, maltase, and alkaline phosphatase specific activities were measured in all animals. Diabetic rats had significantly increased sucrase and maltase but not alkaline phosphatase specific activities compared with control rats. The density of microvillus IMPs on both the protoplasmic and extracellular fracture faces of undifferentiated crypt cells and villus absorptive cells was not increased in experimental diabetes. These data indicate that diabetes does not result in a generalized increase in microvillus membrane proteins. Thus the enhanced activity of microvillus membrane proteins in diabetes appears to be highly selective.
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PMID:Structural features of the rat small intestinal microvillus membrane in acute experimental diabetes. 704 26

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

Activities of intestinal enzymes were measured in genetically diabetic mouse of strain C57BL/KsJ-dbm to determine the long-term effects of genetic and uncontrolled diabetes on intestinal digestive function. Specific activities of enzymes were measured in intestinal homogenates, brush-border membrane fractions, and everted sacs from diabetic mice and their littermate controls. Sucrase, maltase, trehalase, alkaline phosphatase, and leucylnaphthylamidase activities were elevated in diabetes; lactase did not show any changes. The increases in disaccharidase activities in diabetes were in homogenates from both proximal and distal intestine but the increases in distal were more pronounced than in the proximal. Measurement of enzyme activities in brush-border membrane fractions showed a pattern similar to that observed in homogenates. Hydrolysis of sucrose and trehalose by everted sacs was markedly higher in the diabetic mice. It is therefore concluded that in genetic diabetes the digestive function of the intestine is stimulated, that the increased enzymes were incorporated into the brush-border membrane, and that the additional enzymes are accessible to the substrates in the intestinal lumen and so of physiological significance.
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PMID:Effect of genetic diabetes on enzymes of mouse intestinal brush-border membrane. 736 98

The present study was designed to determine the possible significance of a therapeutic dose (0.2 mg) of AO-128 on carbohydrate absorption by measuring the breath hydrogen concentration, which is an index of the amount of unabsorbed carbohydrate in the large intestine. Post-prandial hyperglycemia is common among diabetic patients. AO-128, a potent alpha-glucosidase inhibitor, suppressed post-prandial hyperglycemia and hyperinsulinemia in healthy volunteers at a dose of 0.2 mg with each meal. These volunteers increased the breath hydrogen concentration in response to ingestion of non-absorbable lactulose, but decreased only slightly its concentration from the basal level after sucrose ingestion, indicating complete absorption. When AO-128 (0.2 mg) was given with sucrose, hydrogen production increased only slightly compared with placebo, suggesting that the inhibitory effect of AO-128 on sucrose absorption was minimal. Only 5 g of the 100 g of sucrose was not absorbed and this 5% reduction is too small to explain the observed inhibitory effect on the post-prandial rise in plasma glucose. Sucrose loading in rats (about 443 mg) sharply increased blood glucose and was accompanied by the rapid disappearance of sucrose from the upper small intestine. AO-128 (0.03 or 0.1 mg/kg) lessened the elevation of blood glucose after sucrose ingestion. The lower dose (0.03 mg/kg) retarded small intestinal absorption, but did not induce an influx of sucrose into the cecum and large intestine, while the higher dose (0.1 mg/kg) caused an increased influx of sucrose into the large bowel. These results indicated that AO-128 retards the absorption of carbohydrate and reduces post-prandial hyperglycemia.
Diabetes Res Clin Pract 1995 May
PMID:An alpha-glucosidase inhibitor, AO-128, retards carbohydrate absorption in rats and humans. 758 23

Ten patients with non-insulin-dependent diabetes mellitus who were being treated with a sulphonylureal compound but whose glucose metabolism needed further improvement were given a combination of their usual sulphonylurea treatment and an alpha-glucosidase inhibitor. Treatment with the alpha-glucosidase inhibitor (0.6 mg/day), in addition to glibenclamide (7.5 mg/day in two patients; 5.0 mg/day in four; 2.5 mg/day in one) or tolbutamide (500 mg/day in three patients) for 4 weeks, improved hyperglycaemia after meals from 237-247 mg/dl to 192 mg/dl, and reduced glycosylated haemoglobin levels from 8.5-8.6% to 7.9% without causing hypoglycaemia.
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PMID:Effect of an alpha-glucosidase inhibitor combined with sulphonylurea treatment on glucose metabolism in patients with non-insulin-dependent diabetes mellitus. 758 71

Twenty patients with non-insulin-dependent diabetes mellitus who had been receiving appropriate dietary treatment for 3 months but whose glucose metabolism needed further improvement were treated with an alpha-glucosidase inhibitor. Treatment with the alpha-glucosidase inhibitor (0.6 mg/day) for 4 weeks, had no significant effect on blood glucose levels 2 h after breakfast or on glycosylated haemoglobin levels.
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PMID:No effect of an alpha-glucosidase inhibitor on glucose metabolism in patients with non-insulin-dependent diabetes mellitus and low function of pancreatic beta cells. 758 73

1. We examined the effect of the alpha-glucosidase inhibitor acarbose on urinary albumin excretion (UAE) in streptozotocin diabetic rats. 2. Treatment with acarbose for 8 weeks after induction of diabetes prevented the significant increase in UAE observed in untreated diabetic rats relative to nondiabetic controls. 3. Acarbose significantly reduced integrated glycemia, which correlated with albumin excretion rates, and exerts a salutary effect on diabetic renal dysfunction.
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PMID:Treatment with acarbose, an alpha-glucosidase inhibitor, reduces increased albumin excretion in streptozotocin-diabetic rats. 759 Jan 31

Acarbose (Glucobay-Bayer) is the first in a new class of oral antidiabetic drugs, the alpha-glucosidase inhibitors. It is licensed for the treatment of patients with non-insulin-dependent diabetes mellitus (NIDDM), either as first-line therapy when dietary measures are insufficient, or as an adjunct to conventional oral therapy where glycaemic control is suboptimal. The manufacturer claims that acarbose "can achieve a new level of blood glucose control in diabetes". In this article we consider whether acarbose offers any real advance.
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PMID:Acarbose for non-insulin-dependent diabetes mellitus. 763 34

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

We investigated the relation between activities of islet glycogenolytic alpha-glucosidehydrolases and insulin secretion induced by glucose and 3-isobutyl-1-methylxanthine (IBMX) by means of suppressing 1) insulin release (Ca2+ deficiency) and 2) islet alpha-glucosidehydrolase activity (selective inhibition by the deoxynojirimycin derivative miglitol). Additionally, the in vivo insulin response to both secretagogues was examined. We observed that, similar to glucose-induced insulin release, islet glycogenolytic hydrolases (acid amyloglucosidase, acid alpha-glucosidase) were highly Ca2+ dependent. Acid phosphatase, N-acetyl-beta-D-glucosaminidase, or neutral alpha-glucosidase (endoplasmic reticulum) was not influenced by Ca2+ deficiency. In Ca2+ deficiency IBMX-induced insulin release was unaffected and was accompanied by reduced activities of islet alpha-glucosidehydrolases. Miglitol strongly inhibited glucose-induced insulin release concomitant with a marked suppression of islet alpha-glucosidehydrolase activities. Direct addition of miglitol to islet homogenates suppressed acid amyloglucosidase [half-maximal effective concentration (EC50) approximately 10(-6) M] and acid alpha-glucosidase. Acid phosphatase and N-acetyl-beta-D-glucosaminidase were unaffected. The miglitol-induced inhibition of glucose-stimulated insulin release was dose dependent (EC50 approximately 10(-6) M) and displayed a remarkable parallelism with the inhibition curve for acid amyloglucosidase. The in vivo insulin secretory response to glucose was markedly reduced in dystrophic mice (low amyloglucosidase), whereas the response to IBMX was unaffected. In summary, islet glycogenolytic hydrolases are Ca2+ dependent, and acid amyloglucosidase is directly involved in the multifactorial process of glucose-induced insulin release. In contrast the mechanisms of IBMX-stimulated insulin secretion operate independently of these enzymes. The effects of miglitol, a drug currently used in diabetes therapy, deserves further investigation.
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PMID:Ca2+ deficiency, selective alpha-glucosidehydrolase inhibition, and insulin secretion. 768 25


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