Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D03348 (Lactase)
 283 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

There is controversy both in regard to the severity of small bowel mucosal damage attributable to giardiasis and to the causal relationship of these changes to the associated diarrhoea. In this series of 17 consecutive patients with giardiasis, small bowel histology and diarrhoea were independently assessed and compared. Disaccharidase assays were performed in 16 of these patients and a repeat biopsy obtained in seven cases. On histological examination the villous architecture varied from normal to sub-total villous atrophy. When these changes were compared with the severity of diarrhoea, a direct correlation was obtained, the more severe symptoms being associated with the more severe villous changes. Repeat biopsy after treatment demonstrated improvement in the histology which correlated with improvement in diarrhoea. Lactase activity was low in all patients with moderate or severe diarrhoea as well as in some patients with mild diarrhoea, two of whom had normal histology. This series demonstrates the occurrence of a spectrum of mucosal changes in giardiasis and supports the concept that these changes mediate the diarrhoea associated with this gut parasite.
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PMID:Histopathology in giardiasis: a correlation with diarrhoea. 10 99

Gastric intubation was adopted to examine the effect of continuous nutrient supply on digestive development of the pig during the immediate post-weaning period. The 14 d-weaned animals were slaughtered at 3, 5 and 7 d post-weaning (3W, 5W and 7W respectively) and the suckled animals were slaughtered at 14 and 22 d of age (14SR and 22SR respectively). The weight of the pancreas (g/kg bodyweight) was significantly greater (P less than 0.05) in the 5W and 7W groups, as was the weight of large intestine (g/kg) in all weaned groups (P less than 0.01) compared with sow-reared pigs. The stomach weight (g/kg) tended to be greater in the weaned groups. Weaning, in conjunction with a continuous nutrient supply, did not significantly alter the time-related changes in the weight of the small intestine (SI) or the SI mucosa, although both variables tended to be lowest in the 3W group. However, there was a 20% reduction in the protein content of the mucosa within the first 3 d post-weaning (P less than 0.01) which persisted during the 7 d experimental period. Lactase, (beta-galactosidase; EC 3.2.1.23) activity (mumol/g protein and mol/d) of the 7W group was reduced to approximately 40% of the 22SR value. Hence, continuous nutrient supply may have delayed, but did not prevent, the loss of lactase activity at weaning. The activity of sucrase (sucrose-alpha-glucosidase; EC 3.2.1.48) was significantly higher in 22SR compared with 14SR animals. Sucrase activity in weaned pigs was intermediate to the values for sow-reared pigs whereas maltase (alpha-glucosidase; EC 3.2.1.20) and glucoamylase (glucan 1,4-alpha-glucosidase; EC 3.2.1.3) were significantly increased in relation to their sow-reared counterparts. Continuous nutrient supply did not prevent the reduction in villous height and the crypt hypertrophy associated with weaning. The results of the present study suggest that there may be some degree of interaction between nutrient intake and gut development during the immediate post-weaning period but that there is also a component of the adaptive response which is independent of nutrient intake. They confirm the rapid substrate induction of the brush-border glucoamylases and indicate the importance of considering total as well as specific enzyme activity for satisfactory interpretation of changes in digestive function.
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PMID:Digestive development of the early-weaned pig. 1. Effect of continuous nutrient supply on the development of the digestive tract and on changes in digestive enzyme activity during the first week post-weaning. 190 70

Dietary nucleoside (DN) as a precursor for nucleic acid synthesis may be important for rapidly dividing cells, since gut epithelial cells have limited capacity for de novo purine and pyrimidine synthesis. We evaluated in a controlled blinded study the effect of added nucleosides, 0.8% by weight, given for 2 weeks, on gut growth and maturation in 20 weanling rats. Mucosal protein and DNA in the proximal intestinal segment were 50% and 77% higher, respectively, in the DN-supplemented group (n = 10; p less than 0.05). Villus height based on cell count was 25% greater in the DN group (p less than 0.05). Maltase activity was significantly greater in proximal, middle, and distal intestinal segments, and the largest increase, 87%, was seen in the proximal gut mucosa. The maltase/lactase ratio was also higher in this segment. Increases in sucrase were less prominent. Lactase was minimally affected. The pattern of change in disaccharidase activity suggests that DN may enhance gut growth and maturation of the intestine in the weanling rat, the effects being more pronounced in the proximal segment. Diets free of nucleosides and nitrogenous bases may have adverse effects on the gut.
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PMID:Effect of dietary nucleosides on growth and maturation of the developing gut in the rat. 235 83

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

The activity of lactase enzyme declines after weaning. This study was to investigate changes in the lactase expression in the whole gastrointestinal tract during the development and the possibility that this and activity can be induced by lactose. Expression of lactase protein in the gut of 1-12-weeks old rats was studied by immunocytochemistry. Possible induction was evaluated by immunohistochemical and biochemical techniques in 8-week-old rats after lactose challenge for seven days. Lactase immunoreactivity was detected only in the small intestine and it decreased 20% during the week after weaning. A steady level of 40% lower than in the sucklings was found in the adult rats. In the lactose-challenged rats the optical density of immunoreactivity increased by about 30% in those that consumed the highest concentration of lactose. In the proximal jejunum, elevation of the enzymatic activity was three-fold. In the rat lactase protein expression decreased rapidly after weaning and expression and activity were induced by lactose-rich diet, most notably in the proximal jejunum.
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PMID:Age and continuous lactose challenge modify lactase protein expression and enzyme activity in gut epithelium in the rat. 944 19

Lactase-phlorizin hydrolase, a brush-border membrane disaccharidase, is a marker of intestinal epithelial cell differentiation and digestive function. The intestine is susceptible to conditions of hypoxia resulting from vascular perfusion deficits. We hypothesized that lactase gene induction may provide a mechanism to efficiently increase nutrient energy substrates during gut hypoxia. These studies sought to characterize expression of the lactase gene in response to hypoxia and to characterize a role for hypoxia-inducible factor (HIF-1) in mediating the hypoxic response. Microarray analysis and confirmatory RT-PCR identified a 4-fold induction of lactase mRNA abundance in intestinal epithelial Caco-2 cells exposed to hypoxia. Lactase promoter activity was similarly induced by hypoxia in cells stably transfected with a 2.0-kb 5' flanking region of the rat lactase gene linked to a reporter gene. Transient cotransfection with HIF-1alpha and beta stimulated lactase promoter activity 2.4- and 3.5-fold under conditions of normoxia and hypoxia, respectively. We conclude that HIF-1 can activate the lactase promoter in intestinal epithelial cells exposed to hypoxia. Induction of lactase transcription may represent an adaptive response to gut hypoxia.
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PMID:Lactase gene transcription is activated in response to hypoxia in intestinal epithelial cells. 1182 65

Lactase-phlorizin hydrolase gene expression is spatially restricted along the anterior-posterior gut axis. Lactase gene transcription is maximal in the distal duodenum and jejunum in adult mammals and is barely detectable in the proximal duodenum. By contrast, pancreatic duodenal homeobox-1 (PDX-1) protein is expressed maximally in the proximal duodenum. This study aimed to determine the role of PDX-1 in regulating lactase gene promoter activity in intestinal epithelial cells. Caco-2 cells were cotransfected with lactase promoter-reporter constructs in the presence of a PDX-1 expression vector and assayed for luciferase activity. PDX-1 cotransfection results in repression of lactase promoter activity. Sequence analysis of the lactase promoter revealed a putative PDX-1 DNA binding site in the proximal 100-bp lactase gene promoter. EMSAs demonstrated that PDX-1 can interact with the lactase promoter binding site but not with a site in which the core PDX-1 binding sequence TAAT is mutated. Site-directed mutagenesis of the PDX-1 core binding site in the lactase promoter-reporter construct suggests that PDX-1 can function independently of DNA binding to its consensus binding site. Stable overexpression of PDX-1 results in repression of the endogenous human lactase gene in differentiated Caco-2 cells. Given the contrasting spatial expression pattern, PDX-1 may function to specify the anterior boundary of lactase expression in the small intestine and is thus a candidate regulator of anterior spatial restriction in the gut.
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PMID:Transcriptional regulation of the lactase-phlorizin hydrolase promoter by PDX-1. 1510 97

Lactase is a disaccharidase that is present in the brush-border membrane of the small intestine, hydrolyzes lactose to glucose and galactose, and is therefore important in milk-fed animals. Assays based on quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) in the bovine species have not yet been described. Therefore, we have developed an RT-PCR assay for the quantification of lactase mRNA levels and have tested its suitability in the bovine gastrointestinal tract of seven 5-d-old milk-fed calves. Primers for RT-PCR amplification of bovine lactase mRNA were designed in the 100% identical regions of species (rats, rabbits, humans) from which lactase sequences were available. Lactase mRNA was expressed relative to mean levels of 4 housekeeping genes (glyceraldehyde-3-phosphate dehydrogenase, beta-actin, ubiquitin, and 18S). The presence of lactase mRNA along the entire gastrointestinal tract was evaluated in samples that consisted of whole gut walls (mucosa plus submucosa). Furthermore, mRNA levels of lactase were measured in fractionized layers of jejunal and ileal mucosa (mainly containing villus tips or crypts) and ileal lamina propria (mainly containing Peyer's patches). Agarose gel electrophoresis of the lactase PCR product revealed a single band that corresponded to the single-amplified product as predicted by the melting curve analysis of the PCR. The amplified partial-bovine lactase sequence showed 87% similarity with human and rabbit sequences and 82% similarity with the rat sequence. Lactase mRNA was present in whole walls (consisting of mucosa and submucosa) of the entire small intestine, but was absent in esophagus, rumen, fundus, pylorus, and colon. Furthermore, lactase mRNA was detected in fractionized villus and crypt layers of jejunum and ileum, but levels were higher in the jejunum in villus than in crypt fractions. No lactase mRNA was detectable in the lamina propria fraction of the ileum containing mainly Peyer's patches. In conclusion, the developed RT-PCR method allows study of lactase mRNA levels.
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PMID:Real-time PCR quantification of bovine lactase mRNA: localization in the gastrointestinal tract of milk-fed calves. 1554 87

The effect of enteritis on the development of the small intestine was examined in newborn, colostrum-deprived piglets infected with a human isolate of Y. enterocolitica (serotype 0:3, biotype 4) soon after birth. The piglets were killed 3 days (n = 6) or 5 days (n = 8) after infection, or antibiotic therapy was commenced on day 5 and the animals killed on day 14 (n = 5). Compared with the non-infected controls, infected animals had reduced mucosal lactase and sucrase, but not maltase activity, while after antibiotic therapy, previously infected piglets had a lower lactase and a higher maltase and sucrase activity. Lactase activity was significantly reduced in the duodenum and jejunum, and mean values were lower in the ileum, but the difference did not reach significance; maltase activity was greater at all ages from the distal jejunum to the mid-ileum; sucrase activity was reduced in all segments up to day 5 but after antibiotic therapy was increased in the jejunum and appeared early in the ileum. Enzyme profiles were more mature along the crypt-villus axis in some segments of the intestine in previously infected piglets. Sodium-potassium-ATPase activity was unchanged. There was a reduced villus height:crypt depth ratio, crypt hyperplasia and increased crypt cell proliferation. Morphological maturation, indicated by loss of vacuoles and location of the nucleus at the base of the enterocyte, proceeded distally from the duodenum to ileum from 3 to 14 days of age when only the ileum remained immature. In infected piglets, there was reduced vacuolation and earlier location of the nucleus at the base of the cell in the distal intestine. Accelerated maturity of specific disaccharidases and enterocyte morphology in infected piglets appears to be due to physical damage to the mucosa resulting in faster proliferation of crypt cells and migration of enterocytes. It is suggested that this may reduce macromolecular internalisation and impair the ability to utilise dietary carbohydrate and may have long-term effects on growth and immunological responses of the gut.
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PMID:Impact of Yersinia enterocolitica enteritis on disaccharidase activity and small intestinal morphology in colostrum-deprived newborn piglets. 1603 44

Lactase gene expression is spatiotemporally regulated during mammalian gut development. We hypothesize that distinct DNA control regions specify appropriate spatial and temporal patterning of lactase gene expression. In order to define regions of the lactase promoter involved in mediating intestine-specific and spatiotemporal restricted expression, transgenic mice harboring 100 bp, 1.3- and 2.0- kb fragments of the 5' flanking region of the rat lactase gene cloned upstream of a luciferase reporter were characterized. The 100-bp lactase promoter-reporter transgenic mouse line expressed maximal luciferase activity in the intestine with a posterior shift in spatial restriction and ectopic expression in the stomach and lung. The temporal pattern of expression mediated by the 1.3-kb promoter?reporter transgene increases with postnatal maturation in contrast with the postnatal decline mediated by the 2.0-kb promoter-reporter transgene and the endogenous lactase gene. The differential transgene expression patterns mediated by the lactase promoter fragments suggests that intestine-specific spatial and temporal control elements reside in distinct regions of the DNA sequences upstream of the lactase gene transcription start-site.
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PMID:Lactase gene promoter fragments mediate differential spatial and temporal expression patterns in transgenic mice. 1662 94


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