Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aminopeptidase, lactase and sucrase activities have been followed during 5 days in the jejunum and in the ileum of starved adult rats. Enzyme activities have been determined in the mucosal homogenates as well as in the purified brush border membranes and expressed as activities per intestinal length (segmental activities) or as activities per milligram of protein (specific activities). The segmental and specific activity of aminopeptidase was increased in the ileum during the first 2 days of starvation, suggesting that aminopeptidase may have during the first days of starvation a conservative role by preventing an important loss of tissue protein. In all conditions, lactase activity was strikingly enhanced by starvation whereas sucrase activity showed no changes or decreased activity. Lactase stimulation was initiated during the first 24 h of starvation reaching its maximum after 2 days. The various experimental conditions leading to a specific or to a nonspecific stimulation of intestinal lactase activity have been discussed.
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PMID:Modifications of brush border enzyme activities during starvation in the jejunum and ileum of adult rats. 715 74

The amounts of lactase (EC 3.2.1.23), sucrase (EC 3.2.1.48), maltase (EC 3.2.1.20), microvillus aminopeptidase (microsomal EC3.4.11.2), and dipeptidyl peptidase IV (EC 3.4.14.X) in biopsies from proximal jejunum and distal ileum were studied by quantitative crossed immunoelectrophoresis and enzymatic assays in obese patients one and six months after jejunoileal bypass operation and compared with peroperative levels. They were related to DNA and protein content. The protein/DNA ratio fell 28-43% postoperatively. Except for ileal lactase and sucrase all enzymes showed decreased levels when expressed per mg protein and an even more pronounced decrease when related to DNA. Lactase and sucrase levels in ileum were increased or unchanged. A constant correlation between the amount of immunoreactive enzyme protein and enzymatic activity was shown for all enzymes except maltase. The results suggest that the bypass operation is followed by an increased amount of enterocytes devoid of or low in enzymatic activity and protein content. The amounts of lactase and sucrase in ileum are increased in relation to the other enzymes. No immunoreactive enzymes with zero or depressed activity were detected.
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PMID:Immunoelectrophoretic studies on human small intestinal brush border proteins: cellular alterations in the levels of brush border enzymes after jejunoileal bypass operation. 742 30

We describe the changes of several brush-border enzymatic activities in different subpopulations of epithelial cells, separated sequentially from the villus tip-to-crypt axis of the small intestine, induced by deprivation of dietary nucleotides for different periods of time in adult rats. Deprivation of dietary nucleotides lead to a decrease in the content and specific activity of alkaline phosphatase, leucine-aminopeptidase, maltase, sucrase and lactase in the villus tip, but had little effect on the crypt zone. The effect of the nucleotide deprivation on the enzymatic activity progressively increased towards the tip of the villus. Since these enzymes are maturation markers of the intestinal cells, these results support the idea that dietary nucleotides affect the maturation status of small-intestine epithelium.
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PMID:Maturation status of small intestine epithelium in rats deprived of dietary nucleotides. 772 91

Previous studies in very young rats have shown that dietary nucleotides improve small intestine repair after injury or malnutrition. To investigate the potential effect of nucleotides in old rats, which have a diminished capability for intestinal repair, 17-mo-old rats were deprived of food for 5 d and then fed a nucleotide-free diet or a nucleotide-supplemented diet for 3 or 6 d. Intestinal jejunal and ileal mucosal weight, protein and DNA were evaluated as intestinal growth markers, and brush-border maltase, sucrase, lactase and aminopeptidase activities were evaluated as intestinal differentiation markers. The adenine nucleotide pool and the adenylate energy charge were also evaluated as indices of nucleotide availability. Food deprivation significantly decreased mucosal growth markers as well as differentiation markers in both jejunum and ileum. The ATP pool was also significantly depressed, but the adenylate energy charge was not significantly altered. To a certain extent, refeeding restored the losses, but in the rats that were fed the nucleotide-free diet, the restoration of the jejunum was significantly slower and the restoration of the ileum differentiation markers was incomplete compared with the rats fed the nucleotide-supplemented diet. The results suggest that dietary nucleotide intake in the elderly may accelerate the normal physiological intestinal response to refeeding after food deprivation.
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PMID:Dietary nucleotides accelerate intestinal recovery after food deprivation in old rats. 778 93

We tested the effect of dietary fat on the lipid composition and hydrolase activity of jejunal brush border membranes in piglets. Eighteen 5-wk-old piglets were divided into three groups and for 4 wk fed either an unsaturated low fat diet (3.2% corn oil), an unsaturated high fat diet (17.2% corn oil) or a saturated high fat diet (2.2% corn oil + 15% tallow). Brush border membranes were prepared from the jejunal mucosa and analyzed for cholesterol, phospholipid and fatty acids. The activities of sucrase-isomaltase, lactase-phlorizin hydrolase, maltase-glucoamylase, aminopeptidase and alkaline phosphatase were measured. Lactase-phlorizin hydrolase isoforms were immunopurified and separated by SDS-PAGE, and their relative proportions were measured by densitometry. The activities of the disaccharidases and alkaline phosphatase, but not aminopeptidase, were greater in animals fed the saturated high fat diet than in animals fed the unsaturated high fat diet. The fatty acid composition of the membranes generally reflected the composition of the diet. Correlation analysis demonstrated that the phospholipid, fatty acid and cholesterol compositions of the membranes were associated with the differences in brush border hydrolase activity.
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PMID:Jejunal brush border hydrolase activity is higher in tallow-fed pigs than in corn oil-fed pigs. 793 9

The effect of prostaglandin E2 (PGE2) injection on the postnatal maturation of the 16-day-old rodent small intestine was studied. Previous studies have shown that 16,16-dimethyl PGE2 induced several morphological and biochemical parameters in the small intestine of 11-day-old rats. PGE2 was given subcutaneously daily at doses of 2 and 4 mg/kg body weight on postnatal days 11-15. After treatment there was a rise in the mean activities of sucrase, maltase, lactase and aminopeptidase. In rats receiving 4 mg/kg PGE2, sucrase activity was strongly stimulated (p < 0.001) in the proximal and the distal small bowel. In the duodenum, PGE2 treatment (4 mg/kg body weight) produced a significant increase in crypt depth (35%, p < 0.001), although villus height was not modified. Serum corticosterone levels were significantly increased in PGE2-treated rats. The results seem to indicate that PGE2 accelerates enzymatic and morphological intestinal maturation and this effect could be mediated by an increase in corticosterone.
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PMID:Prostaglandin E2 accelerates enzymatic and morphological maturation of the small intestine in suckling rats. 817 9

The effect of starvation and refeeding on the developmental pattern of intestinal sucrase-isomaltase (SI) was analyzed in preweaned rats. Starvation at postnatal day 12 caused a precocious expression of SI activity and mRNA. Alkaline phosphatase activity was slightly reduced, and no significant change was observed for aminopeptidase and lactase activities. Immunostaining showed that SI molecules appear in cells at the base of the villus. Sucrase expression was further increased by prolonged food deprivation, whereas enzyme activity as well as the amount of SI mRNA dropped to reach the low level found in control sucklings when 48 h-starved pups were refed by returning them to their dams. During the refeeding period, the enterocytes that were committed to produce SI by starvation continued to express the enzyme while migrating up the villi. However, the new epithelial cells arising from the crypts no longer synthesized the disaccharidase. The starvation-evoked appearance of SI was preceded by a transient burst of expression of the protooncogene c-fos, an event that may be correlated to the ontogenic rise of c-fos mRNA observed before weaning. However, in contrast to the normal weaning condition, SI induction by starvation occurred without obvious increase of epithelial cell proliferation and turnover. During the starvation and refeeding period, patterns of sucrase activity and SI mRNA paralleled the serum level of glucocorticoids.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Precocious and reversible expression of sucrase-isomaltase unrelated to intestinal cell turnover. 817 95

To evaluate the role of dietary polyamines in maturation of the rat small intestine, spermine was given orally twice daily to suckling pups from day 10 to day 14 postpartum at different doses: 0, 0.2, 0.5, 1, 2.5, and 5 mumol/dose. Compared to saline treated controls, spermine (5 mumol) produced significant increases in mucosal mass parameters (+12 to +57%, P < 0.05), induced prematurely an adult pattern of microvillous enzymes, and enhanced, respectively, by 19- and 3.5-fold (P < 0.01 vs controls) the concentration of the secretory component of p-immunoglobulins in villous and crypt cells. The response of microvillous enzymes (lactase, sucrase, maltase, and aminopeptidase) to spermine was dose-dependent and -specific since oral administration of arginine (5 mumol) or ornithine (5 mumol) was without effect. Intestinal changes were found to be significant (P < 0.05) for doses of spermine exceeding 1 mumol/day, which is in the range of the amount of polyamines provided by solid pellets at weaning (0.4 mumol/g). However, intestinal changes were undetectable at the physiological amounts of polyamines consumed by pups from rat milk during the suckling period (less than 0.3 mumol/day). Consistent with a direct effect of spermine on the intestinal cell, the cytosolic activity of ornithine decarboxylase was depressed by 27-fold (P < 0.005 vs controls) in the jejunum, while inhibition of ornithine decarboxylase by alpha-difluoromethylornithine did markedly decrease but did not suppress the cell response to spermine. Alternately, plasma corticosteronemia, which was virtually absent by day 14 in controls, ranged between 1.4 and 4.6 micrograms/dl in 60% (N = 9) of the spermine-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Maturation of villus and crypt cell functions in rat small intestine. Role of dietary polyamines. 850 5

The change in activity of three disaccharidase enzymes (maltase, sucrase and lactase) was determined according to the method of Dahlqvist during acute rejection in non-immunosuppressed piglet small bowel grafts. In addition, two brush border enzymes, lactase and aminopeptidase, were stained with monoclonal antibodies. Diminishing disaccharidase activity was an early event during rejection. Diminution began 2 days before distinct morphological changes were seen in the mucosal biopsies. Evaluation of disaccharidase activity can thus be used as a confirmatory method in detecting rejection. Reduction in immunohistological staining of lactase and aminopeptidase with monoclonal antibodies and changes in mucosal morphology were observed to progress simultaneously.
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PMID:Brush border enzymes in evaluation of acute small bowel rejection. 863 16

The extent of positional variation in mucosal enzyme activity along the small intestine was investigated in 14-day-old suckling rats. Samples were taken from ten equally spaced sites along the intestine in 11 rat pups and the activities of the enzymes alkaline phosphatase, neutral aminopeptidase, gamma-glutamyl transferase, lactase and sucrase were measured. All the enzymes except sucrase were subject to considerable positional variation. Alkaline phosphatase and aminopeptidase activities were distributed throughout the intestine, with a broad maximum in the distal intestine. Lactase was also broadly distributed but with greatest activity in the mid intestine. gamma-glutamyl transferase exhibited a novel profile, with a very high proportion of the total activity (78%) present in the distal intestine. Sucrase was essentially absent throughout the intestine.
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PMID:Longitudinal variation in the activities of mucosal enzymes in the small intestine of suckling rats. 879 8


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