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)

Feeding sodium deoxycholate orally to rats for four days caused depression of the activity of the small intestinal enzymes lactase, sucrase, maltase, alkaline phosphatase, and N-acetyl-beta-glucosaminidase. The first four are brush border enzymes, the last a lysosomal enzyme. Alkaline phosphatase activity recovered very rapidly and rebounded to above the normal level within 24 hours. The activity of the three disaccharidases returned to normal within seven days while no recovery was observed within 96 hours of the activity of the lysosomal enzyme, N-acetyl-beta-glucosaminidase, after removing the bile salt from the diet.
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PMID:Deoxycholate depresses small-intestinal enzyme activity. 114 Jun 27

1. Intestinal brush border enzymes have heterogeneous rates of turnover, the largest proteins having the fastest turnover. Since the membrane faces the intestinal lumen, the effects of pancreatic factors were examined in mediating this turnover. Surgical subtotal pancreatectomy was used as an experimental model to study the turnover of brush border proteins in the absence of most pancreatic secretions. 2. Subtotal (95%) pancreatectomy of rats was found to cause elevations by about 50% of total activity and specific activities of certain brush border enzymes (maltase, sucrase, lactase), but not of others (alkaline phosphatase, trehalase). Rats were judged to be functionally deficient in pancreatic proteolytic enzymes (a) by demonstration of vitamin B-12 malabsorption, which was corrected by trypsin, and (b) by the finding of only about 20% of proteolytic activity appearing in the lumen after a test meal when compared to control. 3. To measure protein turnover in vivo the method of double labelling was used, where [3H]- and [14C]valine were administered intraduodenally in sequence 10 h apart. With this technique, a high 3H/14C ratio is correlated with rapid turnover. Proteins with apparent molecular weights of about 200 000-270 000 were found to turn over more rapidly than smaller proteins. 3H/14C ranged from 4.7 to 6.2 in animals without pancreatic insufficiency. In the face of decreased pancreatic proteolysis, the 3H/14C ratio was 2.3-3.1, similar to that of proteins with a slow half life. 4. Estimates of relative synthetic rates of large brush border proteins were lower than normal in pancreatectomized animals, but were constant over the period of the labelling experiment. The high enzyme levels in the face of lower synthetic rates confirms that, at the new steady rate, degradation rates must be slower for large brush border proteins in pancreatic insufficiency. 5. In vitro, using purified brush borders, unfractionated pancreatic enzymes were found to remove sucrase, maltase and lactase, but not alkaline phosphatase and trehalase. The enzyme most potent in this respect was the pancreatic protease, elastase. Non-proteolytic enzymes (amylase, lipase, phospholipase A) were inactive in removing enzyme from the brush border. The addition of elastase to pancreatectomized animals in vivo restored the rapid turnover rate of large brush border proteins. 6. A model is thus proposed for the normal catabolism of some large intestinal brush border proteins. It is suggested that the surface of intestinal absorptive cells is being constantly remodelled, and that certain surface enzymes are in part removed from the membrane by the action of pancreatic proteases. A possible special role for elastase is suggested.
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PMID:The possible role of pancreatic proteases in the turnover of intestinal brush border proteins. 114 88

An experiment was conducted to investigate the mechanisms responsible for the brain lesions, diarrhoea and haemorrhages produced by amprolium poisoning of preruminant lambs. The encephalopathy was preceded by a reduction of cerebrocortical transketolase activity. Diarrhoea was not associated with histological evidence of pathological change in the small intestine, and in lambs with severe diarrhoea the small intestinal levels of alkaline phosphatase and lactase were unaffected. Haemorrhages were associated with a thrombocytopenia which was attributed to degeneration of bone marrow megakaryocytes. The bone marrow of the majority of the lambs which had received amprolium for 3 wk or more was severely depopulated, erythrocyte precursors being the most severely affected. The marrow depopulation was atrributed to decreased cell production, as the majority of the remaining cells showed little evidence of degeneration and the number of mitotic figures in the marrow of amprolium-treated lambs was considerably reduced as compared with the controls.
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PMID:Amprolium poisoning of preruminant lambs: an investigation of the encephalopathy and the haemorrhagic and diarrhoeic syndromes. 115 27

The releases of proteins, maltase, lactase, sucrase, trehalase, alkaline phosphatase, gamma-glutamyltransferase and leucylnaphthylamide-hydrolyzing activity from human intestinal brush bborder membrane vesicles by various enzymes (especially pancreatic proteases) have been studied. The brush border membrane enzymes are not solubilized by digestion with trypsin and chymotrypsin but are largely released after treatment with papain or elastase. Most of the enzymes are fully active after the proteolytic treatment. All proteins released by papain and elastase have been identified by electrophoresis to already known intestinal hydrolases. Electron microscopy of brush border membrane vesicles demonstrates "knob-like" structures (particles) attached to the external side of the membrane. During papain treatment, enzyme removal runs parallel with the disappearance of the particles. During elastase treatment it is not possible to correlate the release of the enzymic activities with the removal of the particles. The results indicate that most of the intestinal hydrolases are surface components attached to the external side of the membrane. They are in accord with the concept that the brush border membrane enzymes are organized within the membrane in a mosaic-like pattern.
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PMID:Enzymic solubilization of the human intestinal brush border membrane enzymes. 127 90

Intestinal disaccharidase activities were determined in 294 jejunal biopsies obtained from 254 children with various disorders of the small bowel, and alkaline phosphatase activity was measured in 251 biopsies. In normal mucosa a broad range of enzyme activity was found corresponding with the data in the literature. A primary disaccharidase deficiency was observed in 5 children with congenital sucrase-isomaltase deficiency and in a 12-year-old Egyptian boy with acquired lactase deficiency. A secondary generalized depression of disaccharidase activity and a diminution of alkaline phosphatase activity existed chiefly in patients who had severe or moderate mucosal damage, also in active coeliac disease and during gluten loading, in protracted diarrhoea of infancy, chronic malabsorption of unknown origin and agammaglobulinemia. During remissions enzyme activities recovered together with mucosal improvement. Low levels of enzyme activities were also seen in some cases of protracted diarrhoea of infancy and chronic malabsorption of unknown origin although only mild mucosal lesions were demonstrated.
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PMID:[Intestinal disaccharidase and alkaline phosphatase activities of jejunal biopsies in small bowel diseases of children (author's transl)]. 127 85

The activity of the small intestine's peptide hydrolases is higher in 1-day old rats than in adult rats, whereas levels of activity of alkaline phosphatase and diglycyl glycine peptidase do not differ significantly in these two groups of the rats. Our own data on carbohydrases corroborate other authors' evidence and reveals that activities of lactase, sucrase and maltase are either absent or very low in the first days of life and sharply increase by the third week of postnatal development. Adaptive changes of regulatory properties of lactase and alkaline phosphatase are revealed.
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PMID:[The detailed characteristics of the enzyme spectrum of the small intestine in rats in the early postnatal period]. 133 21

The brush border of normal small-intestine epithelial cells is rich in enzymes that are involved in the digestive process. Such molecules can be used as markers to analyze cell lineages and differentiation properties of colorectal cancers. Monoclonal antibodies detecting dipeptidyl peptidase-IV, aminopeptidase N, endopeptidase F, sucrase-isomaltase, alkaline phosphatase, maltase-glucoamylase and lactase have been used to analyze the phenotype of colorectal cancers, adjacent mucosa and histologically normal distant mucosa. The avidin-biotin peroxidase complex method was used. Expression of dipeptidyl peptidase-IV, aminopeptidase N, sucrase-isomaltase and alkaline phosphatase was common in non-neoplastic mucosa adjacent to, and distant from, the tumor; in contrast, endopeptidase F, maltase-glucoamylase and lactase were rarely expressed in normal distant mucosa and more frequently expressed in mucosa adjacent to the tumor. Dipeptidyl peptidase-IV, aminopeptidase N, endopeptidase F, sucrase-isomaltase and alkaline phosphatase were frequently expressed in colorectal cancers, whereas maltase-glucoamylase and lactase were rarely expressed. Two general patterns of antibody reactivity were observed: diffuse cytoplasmic and apical; apical reactivity was generally associated with more differentiated tumors. A logistic predictive regression model indicated that enzyme expression in colorectal cancers followed a coordinate pattern, but was unrelated to the location of the tumor, Dukes stage or differentiation grade. In conclusion, expression of brush-border-associated enzymes occurs frequently in colorectal cancers and is regulated in a co-ordinated manner. These markers can be used for the phenotypic sub-classification of colorectal cancers.
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PMID:Intestinal brush-border-associated enzymes: co-ordinated expression in colorectal cancer. 134 6

Suckling rats were given urogastrone-epidermal growth factor (EGF: 1,000 micrograms/kg body weight) or vehicle by gavage at one of three stages of development: 8 to 10, 11 to 13 or 14 to 16 days of age. Intubation was carried out at 8-hourly intervals over these periods. Fourteen to 16 h after the last intubation the rats were killed; that is, at 11, 14 and 17 days respectively. Samples of proximal and distal small intestine (SI) were taken for enzyme analysis. Five enzymes were assayed; sucrase, lactase, gamma-glutamyl transferase, alkaline phosphatase and neutral amino-peptidase, and their activities expressed per g protein. Treatment with EGF had no effect on body weight or on the length of the small intestine at any age. The nature of the effects on enzyme activities depended on the specific enzyme concerned, the site within the small intestine and the timing of the treatment. Lactase was increased by EGF at both sites only on day 14, whereas gamma-glutamyl transferase was increased in proximal samples at 11 and 14 days, and in distal samples at 17 days. Nor was the outcome always to increase activity. On day 11 alkaline phosphatase was increased in proximal SI, but decreased in distal SI; and so too was aminopeptidase N decreased in distal SI at 11 days. Sucrase showed no response at all. The pattern is complex. Certainly it does not indicate accelerated functional maturation.
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PMID:Effects of urogastrone-epidermal growth factor and age at administration on five enzymes in the small intestine of suckling rats. 136 15

The synergistic effects of dexamethasone (DEX) and thyroxine (T4) on the postnatal maturation of the 13-d-old rodent small intestine has been studied. Previous studies have shown that hydrocortisone and T4 produced a synergistic response in enzyme maturation. However, T4 elevates corticosteroid-binding globulin, which reduces the clearance of hydrocortisone. Thus, the apparent synergy between T4 and hydrocortisone may have been due to increased glucocorticoid availability. DEX, which does not bind to corticosteroid-binding globulin, was given (d8-12) at 25 pmol (i.e. 0.01 micrograms)/g body wt/d as established by a dose-response study in which this dose of DEX induced one third the maximum response in sucrase activity. In this way, synergy with T4 (130 pmol/g body wt/d, i.e. 0.1 micrograms/g body wt/d, d 5-12) could still be observed. Glucoamylase, lactase, acid beta-galactosidase, alkaline phosphatase, and sucrase activities were determined in two regions of the small intestine. Overall, the results for the two hormones administered alone showed intestinal maturation to be not significantly affected in the T4 group and partially stimulated in the DEX group. When combined, DEX + T4 synergistically increased jejunal sucrase, ileal glucoamylase, and duodenal alkaline phosphatase, and lowered ileal acid beta-galactosidase. The striking exceptions to the general pattern were two brush border enzymes that normally decline during intestinal maturation, namely ileal alkaline phosphatase and jejunal and ileal lactase. For these enzymes, DEX alone did not elicit precocious maturation, and there was no evidence for a synergistic interaction of these two hormones. Serum corticosterone concentrations also were measured. When corticosterone concentrations were compared with enzyme activity, no correlation was found.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Synergistic effects of thyroxine and dexamethasone on enzyme ontogeny in rat small intestine. 140 67

Metronidazole (Flagyl), an antibiotic commonly used in treating intestinal infections, when administered orally at a dose level of 100 mg/kg body weight daily for 7 days to rats brought about a significant elevation of the uptake of end-product nutrients like D-glucose, L-alanine, L-aspartic acid and L-leucine in the intestinal segments. Brush border membrane-bound hydrolytic enzymes, i.e. sucrase, lactase, maltase, alkaline phosphatase and leucine aminopeptidase levels, were also elevated. Substrate kinetic analysis of the uptake of nutrients as well as the enzymes indicated that the drug increased the maximum of apparent initial velocity, while the substrate affinity constants did not change. Studies of the temperature-dependent parameters of the nutrient uptake and the enzyme activity revealed that metronidazole did not induce any shift in the transition temperature (T(o)) for the uptake but the energy of activation (Ea) was reduced in all the cases except those of maltase and leucine aminopeptidase, which registered an increase in Ea and a marginal shift in T(o), respectively. A significant elevation was seen in the levels of membrane cholesterol, phospholipid, ganglioside and plasmalogen in metronidazole-treated animals, while triglycerides and the non-esterified fatty acids remained unaffected. The effects produced by metronidazole treatment persisted in the animals, which were allowed a recovery period of 7 days after the drug regimen.
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PMID:Effect of the antiprotozoal agent metronidazole (Flagyl) on absorptive and digestive functions of the rat intestine. 147 60


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