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)

Growth failure is a major complication of chronic hypoxemia, as seen in infants and children with cyanotic congenital heart disease. To determine whether chronic hypoxemia during infancy affects the gastrointestinal tract, we examined small intestinal growth and digestive enzyme activities in chronically hypoxemic newborn lambs and in age-matched controls. Chronic hypoxemia was produced by placing an inflatable occluder around the main pulmonary artery and performing a balloon atrial septostomy. Aortic oxygen saturation was reduced to 60-74% for 2 wk, after which the small intestine was removed for analysis. During chronic hypoxemia, somatic growth rate was decreased to 60% of control (hypoxemic, 135 +/- 20 versus control, 216 +/- 26 g/d, p less than 0.02). No differences in caloric intake were found (hypoxemic, 129 +/- 4 versus control, 128 +/- 4 kcal/kg/d). Chronic hypoxemia did not alter small intestinal growth, as measured by jejuno-ileal weight, jejuno-ileal length, mucosal weight, or mucosal protein or DNA contents. However, sp act of lactase, the principal disaccharidase of the infant lamb intestine, were significantly decreased (hypoxemic, 0.08 +/- 0.01 versus control, 0.146 +/- 0.03 units of enzyme activity/mg DNA, p less than 0.05), as were the total small intestinal contents of lactase (hypoxemic, 61.7 +/- 7.0 versus control, 120.6 +/- 21.7 units of enzyme activity, p less than 0.01). There also were decreases in specific and total activities of other digestive enzymes such as maltase, amino-oligopeptidase, and alkaline phosphatase in hypoxemic intestine that did not achieve statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alterations in postnatal intestinal function during chronic hypoxemia. 156 Oct 8

Zidovudine is associated with hematologic toxicity and may also impair the rapidly proliferating intestinal epithelium. However, patients with human immunodeficiency virus (HIV) infection receiving zidovudine gain body weight, indicating improved absorptive function. In the present study, 33 HIV-infected patients with gastrointestinal symptoms who were undergoing duodenoscopy and who had no detectable secondary intestinal pathogens were investigated; 12 of them received zidovudine. HIV antigen p24 was detected in duodenal biopsy specimens by immunohistology in 3 of 12 patients with zidovudine treatment and in 10 of 21 patients without zidovudine treatment. Morphometry of duodenal specimens showed reduced villus surface area (P less than 0.05) without crypt hyperplasia independent of zidovudine therapy and reduced numbers of crypt mitoses in patients with mucosal HIV infection (P less than 0.001) compared with controls. In the duodenal brush border, patients with mucosal HIV infection (P = 0.006) and patients without zidovudine treatment (P = 0.009) had absent lactase/beta-glucosidase activity more frequently than controls, and all HIV-infected patients (P less than 0.025) except zidovudine recipients had decreased alkaline phosphatase activity compared with controls. These findings show a hyporegenerative atrophy of the small intestine and enterocyte dysmaturation associated with mucosal HIV infection. Improved enterocyte maturation, indicated by increased brush border enzyme activity, may contribute to the clinical benefit of HIV-infected patients from zidovudine therapy.
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PMID:Effects of zidovudine treatment on the small intestinal mucosa in patients infected with the human immunodeficiency virus. 156 58

The common hookworm (Ancylostoma ceylanicum) infection of humans was studied in golden hamsters model system. Significant biochemical modulations were observed in hamster jejunal brush border membrane (BBM), the primary site of infection. Analysis of BBM at the peak of infection (3-weeks) revealed a marked decrease in the activities of sucrase, lactase and maltase, while activities of alkaline phosphatase, (Ca2+ + Mg2+)-ATPase and gamma-glutamyl transpeptidase were increased. Kinetic studies conducted with maltase, a superficially localised enzyme of jejunal BBM, revealed loss of enzyme active site during the infection. Among other constituents, the levels of cholesterol and triglycerides were significantly decreased with slight increase in phospholipid content in the infected animals. The hookworm infection also caused a decline in total hexose content indicating an altered membrane glycocalyx. Conversely, there was significant enhancement of hydroxyproline and sialic acid contents. SDS-PAGE analysis showed an enhancement in both low and high molecular weight proteins in jejunal BBM preparations of the infected group. Gel electrophoresis of glycoproteins further revealed the appearance of two additional peaks in the low molecular weight region and concomitant disappearance of a peak in the high molecular weight region. These results strongly support the view that the hookworm infection causes severe damage not to the site of attachment alone but also to the entire cell lining of the jejunum and therefore could influence overall digestion and absorption.
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PMID:Biochemical analysis of jejunal brush border membrane of golden hamster: pathogenic modulations due to ancylostomiasis. 159 19

Ten groups of calves were used to study the changes in activity levels and distribution of seven hydrolases in the intestinal mucosa during development and weaning. The calves in the first group were sacrificed at birth while those in the remaining nine groups were either milk-fed until slaughter on days 2, 7, 28, 56, 70, and 119; or weaned between days 28 and 56 and then slaughtered on days 56, 70, and 119, respectively. The small intestine was immediately cut off and divided into five segments, ie, duodenum, proximal jejunum, median jejunum, distal jejunum, and ileum. In the milk-fed animals, the activity levels of aminopeptidases A and N, alkaline phosphatase, lactase, and isomaltase were maximum at 2 days of age, and then declined sharply between days 2 and 7 but did not change significantly thereafter. By contrast, the maltase activity increased between days 7 and 119, while no sucrase activity was detected. Weaning resulted in a decrease in the activity of lactase and an increase in that of aminopeptidase N, maltase, and isomaltase. The distribution of all these enzymes along the small intestine was slightly influenced by age but not at all by weaning.
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PMID:Activity distribution of seven digestive enzymes along small intestine in calves during development and weaning. 172 29

Paired xenografts of near-term fetal rabbit jejunum were subcutaneously implanted in the backs of athymic nude (nu/nu) mice. At 3 to 4 weeks post-implantation, the grafts had histologic, ultrastructural, and biochemical (lactase, sucrase, alkaline phosphatase, leucine aminopeptidase) parameters comparable to age-matched control rabbits. Four weeks post-transplantation the xenografts were intraluminally inoculated with various strains of lapine attaching and effacing E. coli or group A rotavirus. Infection with 2 strains of E. coli resulted in typical light microscopic and ultrastructural lesions of attachment and effacement. Immunohistochemical analysis of rotavirus-infected xenografts demonstrated rotavirus antigen within enterocytes. These lesions are comparable to those in conventional rabbits. Intestinal xenografts are a novel, highly controlled, and reproducible model which may have unique applications in the study of enteric diseases. The model provides anatomically and biochemically correct intestinal mucosal epithelium uncomplicated by variables such as enteric flora, host immune response, gastric, hepatic, and pancreatic secretions and is susceptible to infection by specific enteropathogens. Xenografts, therefore, may be a viable alternative in certain investigations where whole animals, ligated intestinal loops, organ cultures, or cell cultures might otherwise be chosen.
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PMID:Development, characterization, and utilization of an intestinal xenograft model for infectious disease research. 175 15

To investigate the biosynthetic basis for the mosaic expression of brush border enzymes in confluent Caco-2 cells, a human colon carcinoma cell line exhibiting characteristics of adult small intestinal enterocytes, we have obtained a series of clones differing markedly in their growth rates, amounts of transforming growth factor-alpha/epidermal growth factor-like activity released into the culture medium, and sucrase-isomaltase (SI) activity. Other intestinal markers (aminopeptidase N, dipeptidylpeptidase IV, lactase, alkaline phosphatase and 'crypt cell antigen') displayed a much more limited variability in expression, suggesting that the Caco-2 cell clones we have obtained did not differ in their overall ability to differentiate. Immunofluorescence staining, metabolic labelling with radioactive methionine and hybridization analysis of SI mRNA abundance were used to investigate SI synthesis and its regulation in clones endowed with low, intermediate or high sucrase activity. The results obtained have demonstrated heterogeneous SI expression, even in clonal cell lines, and a negative correlation between SI expression and growth factor concentrations in the culture medium, suggesting an autocrine regulation of cell proliferation and differentiation in confluent Caco-2 cells. Pulse-chase experiments using the two clones endowed with the lowest and highest levels of SI activity, followed by immunoprecipitation of labelled SI with epitope-specific antibodies and SDS/PAGE analysis, suggested that both transcriptional and post-translational mechanisms play a role in the regulation of SI expression in intestinal cells.
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PMID:Clonal analysis of sucrase-isomaltase expression in the human colon adenocarcinoma Caco-2 cells. 176 23

Oral administration of the antiulcerogenic drug, cimetidine, was studied on kidney-bound hydrolytic enzymes at three different dose levels (30 mg, 100 mg, and 2000 mg/kg body weight) and for single administration for 2 and 24 h, and daily administration for 15 days in mice. It significantly inhibited Na+, K(+)-ATPase, Mg(2+)-ATPase, and Ca2+, Mg(2+)-ATPase in the isolated basolateral membrane (BLM). Brush-border-membrane-(BBM)-associated enzymes, sucrase, lactase, maltase, leucine aminopeptidase, and alkaline phosphatase also showed a marked reduction. Substrate saturation kinetics revealed the nature of inhibition was of mixed type in the case of sucrase, lactase, maltase, and alkaline phosphatase (Km was increased, while Vmax decreased), whereas it was of non-competitive type for leucine aminopeptidase (Km was unchanged, while Vmax decreased). In vitro addition of cimetidine (5-20 mM) to the BBM also inhibited the enzyme activity. Dixon plot produced the inhibition constant (Ki) for cimetidine in the case of maltase, alkaline phosphatase, and leucine aminopeptidase in the order of 14.83, 32.83 and 11.5 mM, respectively. Analysis of lipids revealed a significant reduction in BBM-associated phospholipid and phospholipid/cholesterol molar ratio, while the neutral lipid fraction, i.e., cholesterol and triglycerides were not altered. Free fatty acid exhibited an increase after drug treatment, which was significant at higher dose after 24 h of single and 15 days of daily treatment. BLM-associated lipids did not exhibit any significant change. Cimetidine-induced depression in renal BLM- and BBM-associated disaccharidases and ATPases, at least at the higher dose level, may have serious consequences in the absorption of end-product nutrients.
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PMID:Depression of membrane-bound hydrolases by cimetidine in mouse renal basolateral and brush border. 183 34

We have reported the appearance of surfactant-like particles enriched for intestinal alkaline phosphatase and phosphatidylcholine within enterocytes and in the lumen of adult fat-fed rat intestine. Because rat pulmonary surfactant decreases in abundance during the first postnatal days, we examined the developmental expression of these intestinal particles in suckling rats. Electron microscopy revealed abundant particles in 1-day-old rats within and surrounding the villus enterocytes, declining in frequency by day 14. Phosphatidylcholine content, alkaline phosphatase, sucrase-isomaltase, and lactase activity in particles peaked 1 day after birth, declining rapidly to adult levels by day 3 of life, except for sucrase, which peaked again after weaning. The postnatal developmental profile of the same brush-border-associated enzymes was totally different. Membrane fractions enriched for alkaline phosphatase and of similar density to rat surfactant-like particles were isolated from the small intestine of an amphibian (Xenopus laevis) and a fish (grass carp). Electron microscopy of the Xenopus membranes revealed unilamellar structures similar to the rat particles, but the carp membranes were of dissimilar morphology. We conclude that particles with surfactant-like properties in the rat intestine are ontogenically expressed like pulmonary surfactant; similar particles are evident only in animals with lungs.
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PMID:Developmental expression of intestinal surfactant-like particles in rats. 187 97

Serum levels of osteocalcin, a noncollagenous bone matrix protein, have been found to be a specific biochemical parameter of bone formation. In the literature in subjects with osteoporosis, an increased incidence of lactase deficiency has been described. We therefore determined the serum levels of osteocalcin in 10 patients with lactase deficiency and in 20 control subjects by radioimmunoassay. The patients with lactase deficiency were dietary treated and had a very low daily calcium intake. Serum osteocalcin levels were significantly higher in the patients with lactase deficiency than in the control subjects. In contrast, serum levels of parathyroid hormone, alkaline phosphatase, calcium, and phosphorus were not statistically different in the two groups. Our data suggest an increased rate of bone turnover in patients with lactase deficiency on a low calcium diet; possibly calcium supplementation is indicated in dietary-treated patients with lactase deficiency.
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PMID:Increased serum osteocalcin levels in patients with lactase deficiency. 189 34

Although gluten withdrawal is likely to remain the mainstay of treatment for adult coeliac disease, many patients find the diet inconvenient and unpalatable and compliance among asymptomatic patients is often poor. Oral corticosteroids have been used for patients who seem to be resistant to gluten withdrawal but preparations with low systemic bioavailability might be preferable. We have given a new glucocorticoid (fluticasone propionate) to 12 adults with untreated coeliac disease for six weeks while they were on a normal diet. One patient defaulted and one suffered a relapse in a pre-existing neoplasm. Excluding these, there was an improvement of symptoms, a mean weight gain of 2 kg, and a rise in albumin of 5.4 g/l. There was a significant improvement in the lactulose/mannitol excretion ratio (p less than 0.05) and in all histological variables examined in paired biopsy specimens (surface and crypt intraepithelial lymphocyte/enterocyte and goblet cell/enterocyte ratios and enterocyte height, p less than 0.01 or better). In six paired specimens sucrase and alkaline phosphatase activity increased in all (p less than 0.05) and lactase in five of six. No appreciable side effects were observed, but two patients had suppressed cortisol values and synacthen responses at six weeks. A further three, with normal pretrial results, had a blunted tetracosactrin response at six weeks. Fluticasone propionate seems worthy of further assessment in the treatment of coeliac disease as an adjunct to gluten withdrawal.
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PMID:A pilot study of fluticasone propionate in untreated coeliac disease. 190 62


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