Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of various enzymes and transport systems was studied in renal brush-border membrane vesicles (BBMV) isolated from rats injected daily with cyclosporin. Alkaline phosphatase (AP) was strongly stimulated: 55 and 113% increases were obtained in BBMV isolated from rats injected with 10 mg cyclosporin/kg for 5 and 10 days. The affinity of the enzyme remained unaltered, but maximal activity (Vmax) showed a strong increase of 2.4-fold between control and treated animals. In addition to the phosphatase activity, phosphate binding to AP also showed a dose-dependent stimulation by cyclosporin treatment: 44 and 70% increases in animals treated for 5 days with 5 and 10 mg cyclosporin/kg. However, the activity of aminopeptidase M was not affected by these treatments, and polyacrylamide gel electrophoresis of BBMV revealed no alterations in the profile of membrane proteins, suggesting the specificity of cyclosporin interaction with alkaline phosphatase. Na(+)-dependent amino acid and D-glucose transport systems remained unaffected by cyclosporin treatment. The Na(+)-independent transport system for lysine and the Na(+)-H+ antiporter activity were also unaltered. In contrast, the initial rate of phosphate uptake decreased by 28% after administration of cyclosporin (10 mg/kg) for 5 days: the Michaelis constant (Km) and Vmax decreased from 137 to 85 microM and from 1.49 to 1.07 pmol.micrograms-1.5 s-1, respectively. "In vitro" studies with membranes isolated from untreated rats were also undertaken by preincubating membranes with cyclosporin. Neither alkaline phosphatase nor the transport systems were affected under these conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cyclosporin inhibits phosphate transport and stimulates alkaline phosphatase activity in renal BBMV. 167 93

Primary cultures of renal rabbit proximal tubule cells were initiated from a pure suspension of proximal tubule fragments. Proximal tubule cells were grown in a hormone-supplemented, serum-free medium containing low concentrations of antibiotics. Confluent monolayers exhibited multicellular dome formation, indicating the presence of transepithelial solute and water transport. Ultrastructural examination revealed a monolayer of polarized epithelial cells with tight junctions and sparse membraneous microvilli facing the culture medium. Time course biochemical characterization was performed using a palette of 12 enzymes, representative of important metabolic functions or pathways. Brush-border-associated enzymes (gamma-glutamyl transpeptidase and alanine aminopeptidase) were moderately reduced throughout the culture whereas alkaline phosphatase was markedly decreased at confluency. Mitochondrial and lysosomal marker enzymes were well preserved over the culture period. Glutathione-S-transferase activity remained stable during the 16-day culture period investigated. Glycolysis enzyme activities (lactate dehydrogenase and hexokinase) were enhanced, as a function of culture age. Na(+)-K(+)-ATPase activity rise was concomitant with the increase of glycolysis marker enzymes. In contrast, the gluconeogenesis marker enzyme, glucose-6-phosphatase, fell dramatically to reach a low level equivalent to 4% of the activity measured in isolated proximal tubules. Primary cultures exhibited several differentiated functions of the proximal tubule cell: (a) PTH alone was able to induce a significant stimulation of adenylate cyclase activity, unlike isoproterenol, thyrocalcitonin, and arginine vasopressin, and (b) sodium-dependent alpha-methylglucoside (AMG) transport was detected. This AMG uptake was selectively inhibited by phlorizin (5 X 10(-3) M), which is a competitive inhibitor of glucose uptake at the apical membrane. Complete characterization made it possible to investigate hitherto unexplored aspects of in vitro cultured proximal tubule cells. This primary culture model could provide a useful and reliable tool to investigate in vitro renal proximal tubule function, under normal conditions or after a drug-induced toxicity.
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PMID:Biochemical, functional, and morphological characterization of a primary culture of rabbit proximal tubule cells. 167

Ochratoxin A was given orally at 60 microgram/kg body weight in neutral olive oil to Fischer rats for 30 days, at which time they were killed. Clinical state, weights of animals and of their organs and urea and creatinine concentrations were not affected during the exposure period. Significant increases in the activity of enzymes in urine were found: 60% increase in alanine aminopeptidase, 45% increase in gamma-glutamyl-transferase and 90% increase in alkaline phosphatase. These changes indicate early pathological changes in the kidney. Relatively small amounts of the toxin thus affect kidney membrane cells.
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PMID:Effect of ochratoxin A on brush border enzymes of rat kidney. 168 21

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

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

To investigate the role and mechanism of action of epidermal growth factor (EGF) in the intestinal epithelium, we have studied its influence on proliferation and differentiation of Caco-2 cells, a human colon adenocarcinoma cell line exhibiting several characteristics of adult small intestinal enterocytes. A clone of Caco-2 cells synthesizing minimal amounts of transforming growth factor-alpha (TGF-alpha)/epidermal growth factor (EGF)-like activity was used in these studies. Cells grown in the presence of 20-200 ng EGF/ml exhibited increased DNA synthesis and proliferation; formation of morphologically poorly differentiated multilayers was observed at 200 ng EGF/ml. At all concentrations tested EGF produced a significant and marked reduction in sucrase activity, whereas other brush-border enzymes (aminopeptidase N, alkaline phosphatase, dipeptidylpeptidase IV) were only marginally affected. EGF influenced sucrase expression at two different levels. At 20 ng/ml, it affected primarily sucrase-isomaltase processing in the endoplasmic reticulum and/or increased its degradation. At 200 ng EGF/ml, a significant and marked reduction in sucrase-isomaltase mRNA levels and biosynthesis was observed. These results demonstrated that EGF has important and selective effects on Caco-2 cell proliferation and differentiation and may affect different cellular activities depending on its concentration.
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PMID:Inhibition of sucrose-isomaltase expression by EGF in the human colon adenocarcinoma cells Caco-2. 176 18

The present work investigates the ability of galactose to affect enterocyte differentiation during normal development in vivo. Energy intake has also been varied to take account of the fact that galactose is poorly metabolized in mice. Brush-border lactase, alpha-glucosidase, dipeptidylpeptidase-IV, aminopeptidase N, alkaline phosphatase and microvillus length were measured as markers of enterocyte differentiation in mice fed diets containing galactose (G diet), corn oil (E diet) or galactose + corn oil (G + E diet). Maintaining mice on a G instead of E diet reduced brush-border lactase activity and enterocyte migration rates; alpha-glucosidase, dipeptidylpeptidase-IV, aminopeptidase N and microvillus length expression increased and alkaline phosphatase activity remained unchanged. Feeding the G + E diet restored enterocyte migration rates, lactase, aminopeptidase N and dipeptidylpeptidase-IV activities to values found in mice fed the E diet. Galactose stimulation of alpha-glucosidase and microvillus length expression was, however, fully maintained in mice fed the G + E diet. Present results show that enterocyte differentiation is affected independently by varying dietary galactose and energy levels; that galactose effects always increase and energy effects usually decrease expression of enterocyte components and that energy stimulation of lactase activity is exceptional.
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PMID:Galactose effects on enterocyte differentiation in the mouse jejunum. 190 92

1. Change in digestive enzyme activities determined biochemically in brush-border membrane vesicles and cytochemically in isolated villi of lamb proximal intestine has been related to diet, intestinal structure and rumen development during the first 10 weeks of postnatal life. 2. Lactase activity halved, dipeptidylpeptidase IV activity doubled and aminopeptidase N and alkaline phosphatase activities remained constant during this period of development. Maintaining lambs on a milk replacer diet for 5 weeks after birth had no effect on this pattern of postnatal change in digestive enzyme activities. 3. Structural changes accompanying these selective effects on enzyme expression included a halving of villus height and a doubling of villus width. Villus surface area remained unaffected by these changes in height and width of villi. Crypt depth doubled during the first 10 weeks of postnatal life. Maintaining lambs on a milk replacer diet for 5 weeks did not affect this pattern of change in intestinal structure. 4. It appears from these results that postnatal decrease in lactase and increase in dipeptidylpeptidase IV activities are not regulated by factors such as diet, rumen development, or changes in intestinal structure. Attention is drawn to differences encountered between these results and a postnatal modification of glucose transport which clearly is dependent on diet.
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PMID:Postnatal development of lamb intestinal digestive enzymes is not regulated by diet. 190 59

The effects of the histidine modifier, diethyl pyrocarbonate (DEPC), on brush-border membrane transport systems were studied in rat kidney. DEPC caused a strong inhibition of sodium-dependent phosphate and D-glucose uptake. Phosphate uptake remained linear up to 10 s in control and DEPC-treated membrane vesicles. The D-glucose carrier was more sensitive than the phosphate carrier with half-times of inhibition being 4 and 7 min, respectively. Sodium-independent phosphate and D-glucose uptake remained unaffected by DEPC. Intravesicular volume and two enzyme activities endogenous to the luminal membrane (alkaline phosphatase and aminopeptidase M) remained unaffected by DEPC. Increasing the preincubation pH from 5 to 9 increased phosphate transport inhibition caused by DEPC from 73 to 88% in the presence of DEPC. Hydroxylamine was able to completely reverse phosphate uptake inhibition by DEPC (100%), but only partially reversed the D-glucose uptake inhibition (16%). Sodium or substrate (D-glucose or phosphate) in the preincubation media were unable to protect their respective carriers from DEPC. Sodium-dependent transport of L-glutamine, L-phenylalanine, L-leucine, L-alanine, L-glycine, beta-alanine and L-proline were inhibited at different levels ranging from 70 to 90%. Three transport processes were found insensitive to DEPC modification: L-glutamate, L-lysine and D-fructose. None of the amino acid transporters was protected against DEPC by sodium and/or their respective substrates. Sodium influx was inhibited by DEPC (47%) in the absence of any substrate. Our results show a differential sensitivity of sodium-dependent transporters to DEPC and suggest an important role for histidine residues in the molecular mechanisms of these transporters. More experiments are in progress to further characterize the residue(s) involved in these transport inhibitions by DEPC.
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PMID:Kidney brush-border membrane transporters: differential sensitivity to diethyl pyrocarbonate. 191 27

Eight cases of acute myelogenous leukemia with (8; 21) translocation were reported. As recently reported, they showed following features: M2 morphology in FAB classification (all 8 patients), abnormal granulocyte maturation, i.e. large granules and pseudo Pelger-Huet forms (5), Auer rods (8), occasional eosinophilia (2), frequent loss of one sex chromosome (5), the low neutrophil alkaline phosphatase activity (5), and tumor formation (one). Both CD13 and CD33 antigens were expressed on smaller number of leukemic cells than the other AML (M2) cells, whereas CD34 and HLA-DR antigens were expressed on higher number of cells. Interestingly CD19 antigen was detected on a small to large population of tumor cells from four out of six patients. Despite the high remission rate, many of them relapsed within one year. More intensive postinduction and maintenance therapy should be considered for those patients.
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PMID:[Clinical and cytological features of acute myelogenous leukemia with 8; 21 chromosome translocation]. 192 Aug 38


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