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:3.2.1.26 (invertase)
4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Brush border sucrase and lactase activities are significantly elevated in alloxan-induced chronic diabetes and are restored to control levels after insulin treatment. Alkaline phosphatase and Mg-ATPase levels remain unchanged in diabetes, compared to a control group. Insulin treatment alone to control animals also led to enhanced activities of these enzymes.
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PMID:Effect of chronic alloxan diabetes and insulin administration on intestinal brush border enzymes. 14 19

The uptake of macromolecular markers by fluid pinocytosis in the rat yolk sac was inhibited by glucagon, with half-maximal effect at a hormone concentration of approximately 3 X 10(-8) M. Glucagon had no effect on the cellular distribution of the marker subsequent to its uptake. Rates of uptake promptly returned to normal when the yolk sacs were transferred from a glucagon-containing to a glucagon-free medium. Epinephrine also inhibited, but only at much higher concentrations. The effect of the latter was augmented by theophylline. Insulin (10(-6) M) had no effect when added alone or with an inhibitory level of glucagon (10(-7) M). The presumption that the hormone effect was mediated by cyclic AMP was supported by the findings that the cellular levels of cyclic AMP were elevated in the presence of glucagon and that dibutyryl cyclic AMP could replace glucagon as an effective inhibitor. The conclusion that the hormone effect was on uptake rather than on subsequent regurgitation was based on the linearity of accumulation in both the presence and absence of glucagon and the inability of glucagon to stimulate loss of invertase from preloaded cells. Colchicine and vinblastine also inhibited uptake. This finding and those of others which are discussed suggest the possibility that effects of cyclic nucleotides on certain cell functions may involve their regulation of microtubular status.
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PMID:Effect of glucagon on pinocytosis by the yolk sac of the rat. 90 54

In ad libitum-fed diabetic rats, sucrase specific activities in jejunum and ileum were significantly increased two- to threefold compared to controls, a response unaltered by pair-feeding. Gradients of sucrase activities along the ileal villus-to-crypt axis were readily measured in crypt regions in diabetic, but not in nondiabetic, rats. Changes in sucrase activities were commensurate with increases in sucrase immunoreactivity and not a result of altered functional activity. Insulin treatment reversed these effects, although insulin-deficiency, studied in food-deprived, nondiabetic rats, did not affect sucrase expression. We conclude that chronic diabetes significantly stimulates sucrase expression along the proximal-to-distal and villus-to-crypt axes of rat small intestine. In ileum, these changes suggest marked alterations in phenotypic development of enterocytes along the villus-to-crypt axis. Alterations in sucrase expression do not appear to correlate with insulin states and are not a consequence of altered functional activity.
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PMID:Regional alterations in intestinal sucrase expression in streptozocin-treated chronically diabetic rats. 161 56

Insulin has been proposed as an important factor in the regulation of growth and differentiation of the small intestine. In the newborn miniature pig, we induced significant physiologic increases in serum insulin and the insulin/glucagon ratio without altering serum glucose, beta-hydroxybutyrate, glucagon, cortisol, T3, and T4 using glucose-based total parenteral nutrition (TPN) in one group (group G) compared with a combination of glucose and fat in another group (group G/F). Control animals were sham-operated and fed a pelleted diet (group OC). Duodenal villus surface area and mucosal height were significantly greater in group G/F compared with group G. No other differences between the TPN groups were found in small intestinal growth, mucosal protein, deoxyribonucleic acid and ribonucleic acid content, and disaccharidase activities. As anticipated, group OC demonstrated increased intestinal length, weight, and villous surface area compared with the TPN groups. Ileal sucrase and jejunal and ileal maltase activities were greater in the TPN groups compared with those in group OC. Physiologic changes in serum insulin and the insulin/glucagon ratio induced by the TPN fuel mix do not appear to have altered small intestinal growth, composition, and differentiation in the healthy small intestine.
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PMID:Effect of different total parenteral nutrition fuel mixes on small intestinal growth and differentiation in the infant miniature pig. 249 81

Insulin affects the expression of brush border enzymes by villus cells in vitro and in vivo. Physiological (lactation) and surgical (jejunoileal bypass) models of hyper- and hypoplasia were established so that insulin receptor characteristics could be related to villus histology, expression of sucrase and alkaline phosphatase, and plasma insulin concentrations. In lactating rats, villus height increased up to 55% (p less than 0.005), and fasting plasma insulin increased 71% (p = 0.005), compared with controls. Insulin binding to villus cell membranes, and sucrase and alkaline phosphatase activities were, however, unchanged. In ileum of bypass operated rats, villus height increased 134% (p less than 0.005) while insulin binding fell 68% (p = 0.025). Scatchard analysis revealed that this was largely because of reduction in binding by high affinity receptors. Sucrase and alkaline phosphatase specific activities fell 57% (p = 0.03) and 49% (p = 0.02) respectively, suggesting that ileal villus cells were hypomature. The slightly hypoplastic tissue of selfemptying loops showed normal insulin binding compared to jejunum of sham operated controls. Bypass and sham operated rats had similar fasting plasma insulin concentrations. Reduced insulin binding in markedly hyperplastic gut of bypass operated rats might reflect hypomaturity of villus cells. The reduction in insulin binding, however, might significantly modulate the effect of insulin on small intestinal mucosa and account for the fall in enzyme activity which occurs despite villus hyperplasia.
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PMID:Effects of intestinal adaptation on insulin binding to villus cell membranes. 331 13

Intestinal adaptation has been studied in rats with pancreatic atrophy induced by feeding a copper-deficient diet and penicillamine and in rats with carbohydrate maldigestion induced by feeding of an alpha-glucosidase inhibitor (acarbose). Pancreatic atrophy led to a significant increase of weight, protein, and DNA content as well as specific activities and total amounts of the enzymes sucrase and maltase in the distal but not in the proximal part of the small intestine. Plasma levels of CCK and GIP were significantly higher in rats with pancreatic atrophy, whereas plasma levels of gastrin and insulin were lower. Tissue concentrations of gastrin in the antrum and GIP in duodenum and jejunum were unchanged. Duodenal CCK and jejunal substance P, somatostatin, and VIP and ileal substance P and somatostatin were significantly decreased in rats with acinar atrophy. Glucosidase inhibition by acarbose feeding led to weight increase of the small intestine and cecum. This was more marked when acarbose was fed together with a fiber-free diet. Under these conditions the protein and DNA content also increased significantly in both gut segments and maltase and sucrase content predominantly in the distal part. Insulin plasma concentration decreased significantly in the acarbose-fed groups, whereas GIP, gastrin, and CCK plasma concentrations remained unchanged. After fiber-rich diet tissue concentrations of gastrin in the antrum and insulin in the pancreas were significantly higher and GIP concentrations in the duodenum and jejunum significantly lower than after fiber-free diet. Acarbose increased the pancreatic insulin concentration only in the fiber-free group and did not influence gastrin and GIP concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Adaptation of the small intestine to induced maldigestion in rats. Experimental pancreatic atrophy and acarbose feeding. 389 54

Diabetes was induced in rats by administration of streptozotocin. After 90-120 days, one group of chronic diabetic animals was treated with insulin for chronic diabetic animals was treated with insulin for 10 days. The lipid fluidity and composition of microvillus membranes prepared from ileal enterocytes of control, diabetic, and insulin-treated diabetic animals were determined. Lipid fluidity, as assessed by steady-state fluorescence polarization techniques using the probes 1,6-diphenyl-1,3,5-hexatriene, DL-2-(9-anthroyl)stearic acid and DL-12-(9-anthroyl)stearic acid, was decreased in membranes of diabetic animals compared to membranes of control and insulin-treated diabetic membranes. The differences in fluidity resulted from an increased cholesterol content and cholesterol/phospholipid molar ratio in membranes of diabetic animals. The activities of sucrase and alkaline phosphatase were also found to be higher in membranes of diabetic animals. Insulin treatment, however, failed to significantly influence the enzymatic activities of these membranes. These studies, therefore, demonstrate that alterations in the lipid fluidity, lipid composition, and certain enzymatic activities exist in microvillus membranes of enterocytes prepared from chronic streptozotocin-induced diabetic rats. Administration of insulin for 10 days to these animals restored membrane fluidity and lipid composition but not enzymatic activities to control membrane levels.
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PMID:Correction of abnormal lipid fluidity and composition of rat ileal microvillus membranes in chronic streptozotocin-induced diabetes by insulin therapy. 390 76

Fasting reduced small intestinal length. It also decreased mucosal weight, DNA and protein content, and concentrations of enterokinase, maltase, and sucrase in both duodenal and jejunal segments. In contrast, the concentrations of lactase and leucine aminopeptidase were not affected. Concomitantly, serum insulin levels dropped to one-fifth of the control levels while serum glucose concentrations showed a lesser degree of reduction. Glucose supplementation alone raised the serum insulin level, prevented the decrease in DNA content, and showed a protective effect on mucosal protein, mucosal weight, mucosal thickness, and villus height. Glucose also protected the sucrase and maltase concentrations; more significantly for maltase in the jejunal segment. Insulin alone, although it increased the serum insulin level to that found with glucose supplementation alone, had no protective effect on the loss in protein, DNA, and most enzymes except for maltase concentration in the jejunal segment. Addition of insulin to glucose did not modify the glucose effect on the contents of DNA, protein, and concentrations of sucrase and maltase. These results suggest that the glucose effect on the mucosa is not mediated by insulin. In addition, the retention of both maltase and sucrase activities through only glucose supplementation suggests the loss of maltase and sucrase in fasting is due to nutrient rather than specific substrate restriction.
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PMID:Effect of glucose and insulin on small intestinal brush border enzymes in fasted rats. 640 48

Jejunal mucosa of 6 d-old rats were cultured for 24 and 48 h in the presence of thyroxine, insulin, pentagastrin, glucagon, epidermal growth factor (EGF) or dibutyryl-A-3:5-MP cyclic with or without dexamethasone (DX). The enzymes were assayed on the purified brush borders. The various agents added alone to the basic culture medium had no effect with the exception of DX on the levels of enzyme activities. Dexamethasone alone induced sucrase, stimulated maltase, and protected other brush border enzyme activities (aminopeptidase, lactase, and alkaline phosphatase). When added to DX-supplemented medium, only the following factors modified the levels of enzymatic activities observed with DX alone. Insulin (10(-6) M) increased maltase, alkaline phosphatase, and lactase activity to a greater extent than DX at 24 h culture, the effect being maintained at 48 h on alkaline phosphatase only. At 48 h culture, both EGF (10(-8) M) and dbcAMP (10(-3) M) decreased DX-induced sucrase activity. The latter agent also depressed DX-stimulated aminopeptidase activity.
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PMID:Organ culture of suckling rat intestine: comparative study of various hormones on brush border enzymes. 674 50

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


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