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)

In order to study the establishment of regional differences in brush border enzymic activities during the development of fetal mouse small intestine we have followed (1) the differentiation of microvilli by morphometry, and (2) the developmental pattern of three brush border enzymes (lactase, glucoamylase and alkaline phosphatase). From day 16 to day 19 of gestation, the height of duodenal microvilli increases 2.4 times on the absorptive cells located near the tip of the villi. During the same period in the upper half of the duodenal villi, the number of microvilli per square micrometer rises by a factor of 2.4 and the microvillous surface area increases by a factor of 5.2. The differentiation of ileal microvilli follows a similar pattern but they are always shorter and less numerous than those of the duodenum. Lactase activity appears at 18 days of gestation; the other two brush border enzymes are first detected at 16 days of gestation. Afterwards all three enzyme activities increase rapidly and a decreasing gradient of activity is established from the proximal to the distal segment of the small intestine. Hence, the structural development of the microvilli and the appearance of brush border enzyme activities occur simultaneously and a proximo-distal gradient is already established at 16 days of gestation.
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PMID:Establishment of regional differences in brush border enzymatic activities during the development of fetal mouse small intestine. 678 53

The intestinal disaccharidases, lactase, sucrase-isomaltase complex, and glucoamylase are proteins intimately associated with the brush-border membrane of the epithelial cell. These three enzyme activities are found in the intestine of the adult rat; lactase and glucoamylase activities are primarily associated with the intestine of the infant rat. Only glucoamylase and isomaltase activities are detected in the intestine of the California sea lion, Zalophus californianus. The activities of these enzymes are detected only in villus cells, and not in crypt cells. We have carried out electron microscopic studies of negatively stained brush-border preparations of intestinal crypt and villus cells; from the intestine of the 10-day-old rat and from that of the California sea lion. The density of the knob-like structures protruding from the brush-border membranes was not significantly different in any of these preparations. The diameter of the knobs on the preparations from crypt cells was smaller than the diameters of the knobs found on membranes prepared from the other sources. These data are discussed in terms of the relationship between the presence of knob structures and disaccharides activities associated with the brush-border membranes.
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PMID:Disaccharidase-deficient animals have normal ultrastructure of intestinal brush border membranes. 679 15

Proximal and distal parts of the small intestine of 8-day-old suckling mice can best be maintained for 48 h in a serum-free organ culture system, Leibovitz L-15, at room air and room temperature. As determined by light and electron microscopy, the villous architecture was preserved as well as the classical ultrastructure of the enterocytes. Incorporation of 3H-thymidine and 3H-leucine continued during the culture period, reflecting a sustained synthesis of DNA and proteins for at least 48 h. The hydrolytic activities of the brushborder membrane, namely of lactase (L), trehalase (T), glucoamylase (GA) and alkaline phosphatase (AlPase) were measured in the explants as well as the culture medium. The overall enzymatic activities were increased as compared to the controls. In the tissue, L, GA and T activities remained stable or even increased during culture while in the medium an accumulation of enzymatic activities was noted especially for GA an AlPase. These results show that the morphological as well as the functional integrity of the mucosa is preserved for at least 48 h when small intestine of suckling mice is cultured in a serum-free medium.
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PMID:Organ culture of the small intestine of the suckling mouse in a serum-free medium. 683 27

1. The levels of the brush-border enzymes sucrase (sucrose glucohydrolase, EC 3.2.1.48), isomaltase (oligo-1,6-glucosidase, EC 3.2.1.10), maltases 2 and 3 (glucoamylase, EC 3.2.1.3), lactase (beta-galactosidase, EC 3.2.1.23) and trehalase (EC 3.2.1.28) and adsorbed pancreatic alpha-amylase (EC 3.2.1.1) have been measured at twenty-one positions along the small intestines of eighty-four pigs of different ages ranging from 3 weeks to 4.5 years. The state of dilation of the intestine at the sampling points was noted. 2. The levels of sucrase and isomaltase increased with age throughout the age-range studied. Trehalase and the glucoamylases increased with age up to 200--300 d of age. Lactase decreased with age over the whole age range. 3. For the pigs above 10 weeks of age, the distribution pattern of the brush-border enzymes along the intestine did not change with age. Each enzyme had a characteristic distribution curve, with low values at the proximal and distal ends and a peak which was proximal in the instance of lactase and trehalase and approximately mid-way along the gut with sucrase, isomaltase and the glucoamylases. 4. The pattern of distribution of the brush-border enzymes altered with age in the piglets, but approached the adult pattern by 8 weeks. 5. Piglets weaned at 3 weeks had higher levels of sucrase, isomaltase and glucoamylases at 5 weeks than piglets left on the sow. At 8 weeks of age the piglets weaned at 3 weeks still had higher sucrase and isomaltase levels than those on the sow. 6. There was a very close correlation between the sucrase and isomaltase levels, and between the maltase 2 and maltase 3 levels in all the samples, and a fairly close correlation between all these four enzymes. 7. The level of alpha-amylase increased with age but showed no regular distribution pattern, its irregular fluctuations being related to the presence or absence of dilation of the intestine at the time of slaughter rather than to the position along the intestine.
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PMID:The level of distribution of carbohydrases in the small intestine mucosa of pigs from 3 weeks of age to maturity. 696 56

Explants of pig small intestine were maintained at 37 degrees C in organ culture for periods up to 24 h in a system using Trowell T-8 medium supplemented with 10% foetal-calf serum. The mucosal morphology was well preserved during culture, as judged by light and electron microscopy. The explant contents of protein and two brush-border enzymes, microvillus aminopeptidase (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5), were not significantly modified during culture compared with controls, but a moderate, continuous release of both protein and enzyme activities into the medium was observed. Continuous labelling with [35S]methionine resulted in an even incorporation of radioactivity in the protein components, and the rate of labelling only moderately decreased over the 24 h period. The polypeptide compositions of sucrase (EC 3.2.1.48)--isomaltase (EC 3.2.1.10), maltase--glucoamylase (EC 3.2.1.20) lactase (EC 3.2.1.23)--phlorizin hydrolase (EC 3.2.1.62), microvillus aminopeptidase and aspartate aminopeptidase (EC 3.4.11.7) synthesized during culture were studied, and some were found to be similar to those of the pro-forms of the enzymes isolated from animals that had had their pancreatic duct disconnected 3 days before being killed. These results confirmed earlier findings of the existence of pro-forms of some of the microvillar enzymes and thus indicate a low activity of pancreatic proteinases in the culture system.
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PMID:Biosynthesis of intestinal microvillar proteins. Characterization of intestinal explants in organ culture and evidence for the existence of pro-forms of the microvillar enzymes. 709 36

Suspensions of sequentially isolated villus and crypt cells were obtained in order to study certain biochemical changes associated with differentiation of epithelial cells in the small intestine of the mouse. Microscopic observation of the various cell fractions reveals that the epithelial cells detach as individual cells or small sheets of epithelium from the tip to the base of the villus, whereas cells in the crypt regions are separated as entire crypt units. The isolated cells retain their ultrastructural integrity as judged by electron miscroscopy. Chemical characterization of the various fractions shows that the total cellular protein content, expressed in activity per cell, remains relatively constant throughout the villus region followed by a noticeable drop in the crypt zone. On the other hand, sharp variations in values of cell DNA content are observed in the crypt zone depending on the reference of activity being used. Activity profiles of several brush border enzymes confirm the biochemical changes that occur during the migration of cells from the crypt to the villus tip, as observed in other species, with maximum activity of sucrase in the mid-villus region, of glucoamylase, trehalase, lactase and maltase in the upper third region, and of alkaline phosphatase at the villus tip. Forty-eight-hour suspension cultures of cell fractions corresponding to cells at the base of the villus and crypt zones show a moderate decrease in protein and enzyme activities to approximately 70% of their original value, with DNA content remaining stable throughout the incubation period. The use of biochemical activities as indicators of cellular integrity during cell culture is discussed.
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PMID:Characterization of isolated villus and crypt cells from the small intestine of the adult mouse. 741 92

Mucosal surface area, protein, DNA and RNA content, [3H]-thymidine incorporation, total activity of glucosidases, peptidases, phosphatases and transaminases were measured in the duodenum and in the middle and lower parts of the small intestine of the domestic pigeon Columba livia. Mucosal surface area, protein, nucleic acid content and [3H]-thymidine incorporation were significantly higher in the duodenum and in the middle part of the small intestine than in the lower part. Whereas the activities of alkaline phosphatase, sucrase, cellobiase and lactase were significantly higher in the middle part of the small intestine, those of maltase, glucoamylase and leucine aminopeptidase were significantly higher in the lower part. It is concluded that in Columba livia small intestine, regional differences are more pronounced between the middle and the lower parts of the small intestine than between this middle part and the duodenum.
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PMID:Regional differences along the small intestine of the pigeon (Columba livia): histobiochemical evidences. 769 Dec 16

Exogenous glucocorticoids administered during the first two postnatal weeks are capable of eliciting precocious maturation of the rat intestine. However, it is not known whether this represents an alternative developmental pathway or is essentially an advancement of normal ontogeny. The goal of the present study was to address this question using the thymidine analogue 5-bromo-2'-deoxyuridine (BrdU), which is known to selectively inhibit differentiation in a number of tissues. Intestinal development was assessed by following changes in sucrase, trehalase, glucoamylase, and lactase activities. The first experiment assessed whether BrdU has any influence on the cellular differentiation that occurs continuously along the crypt-villus axis. After administration of BrdU to suckling and mature animals, there was no effect on lactase and sucrase activities, respectively. Thus BrdU does not inhibit crypt-villus differentiation in either the suckling or mature jejunum. In the second experiment, dexamethasone was used to induce precocious maturation in the rat jejunum on day 10. BrdU treatment significantly inhibited glucocorticoid-induced elevation of sucrase, trehalase, and glucoamylase but had no effect on the lactase activity. In contrast, treatment with BrdU during normal development significantly accelerated the ontogenic rise of sucrase and trehalase as well as the ontogenic decline of lactase. The acceleration of development was also seen in adrenalectomized rats, indicating that it is the glucocorticoid-independent component of normal intestinal ontogeny that is activated by BrdU. The opposite effect of BrdU on glucocorticoid-induced precocious maturation suggests that such maturation involves different molecular mediators than normal ontogeny.
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PMID:Distinguishing normal and glucocorticoid-induced maturation of intestine using bromodeoxyuridine. 784 Jan 97

Nocardia delipidated cell mitogen (NDCM) was given intragastrically (200 micrograms/animal) to 2-month-old germ-free (GF) and conventionally (CV) reared AVN rats. On day 4, enzymatic activities of enterocyte brush border membrane vesicles (BBMV) isolated from jejunal scraping were measured. The results indicated that activities of sucrase, lactase and glucoamylase in BBMV were stimulated following NDCM treatment. The most pronounced increase of enzymatic activities was found in GF rats. In contrast to CV rats, GF rats do not express MHC class II on epithelial cells during their life. NDCM treatment induced MHC class II expression in enterocytes from GF rats. The levels of IgA and IgG in sera from NDCM-treated CV rats did not change significantly. The level of IgG in sera of GF rats was found to be enhanced after NDCM treatment. Markedly increased incorporation of 3H-thymidine by spleen lymphocytes stimulated with Con A in vitro was observed only in NDCM-treated GF rats. 3H-uridine incorporation into Con A-stimulated lymphocytes of GF rats was decreased after NDCM treatment.
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PMID:Stimulation of enterocyte enzymatic activities, MHC class II expression and other immunological factors after oral treatment with Nocardia delipidated cell mitogen in germ-free rats. 792 98

This study aims to determine the effect of glucose and glucose polymers (GP) from corn in oral rehydration solutions (ORS) on disaccharidases and morphometric measurements in small intestinal mucosa of rats. ORS containing standard composition of salts as in WHO ORS and 2, 5, or 10 per cent glucose or GP [initial glucose polymers, long chain (> 9 molecules) and short chain (2-9 molecules) glucose polymers] from corn were infused into the duodenum of 72 Sprague-Dawley rats (250-350 g). Six rats were sham operated as controls. The levels of lactase, sucrase, maltase, palatinase, and glucoamylase enzymes were higher in rats infused with ORS-containing glucose or GP than control rats. Villus height, villus width, and crypt height in corresponding segments of duodenum, jejunum, and ileum were not significantly different between rats perfused with ORS containing glucose polymers from corn and those with ORS containing glucose. ORS containing GP from corn have no adverse effects on small intestinal enzymes and morphometric measurements.
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PMID:Effect of perfusion of oral rehydration solutions containing glucose polymers from corn on disaccharidases and mucosal morphology in rat small intestines. 807 18


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