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)

HT-29 Human colonic adenocarcinoma cells when grown on a plastic substratum were anaplastic in appearance and failed to express any morphological or biochemical features that were characteristic of intestinal differentiation. Growth of HT-29 cells subcutaneously in the flank of immune deprived mice gave rise to morphologically heterogeneous tumors which were poorly differentiated but contained approximately 11% of cells with an intestinal phenotype: these showed features typical of cell polarization with well-developed microvilli, tight junctional complexes and desmosomes between adjacent cells. The transfer of cells from plastic onto either a fixed (designated 'non-released') or floating (designated 'released') type I collagen gel induced some morphological features typical of intestinal differentiation; for example goblet-like cells were observed after 9 days, but biochemical markers of differentiation were expressed only modestly. The continued subculture of HT-29 cells on collagen type I gels, which were either attached to the plastic or floating in the medium, induced some morphological features of intestinal differentiation and changes in the activity of brush border-associated enzymes. Alkaline phosphatase activity was enhanced from 1.3 x 10(-3) mumoles/mg/min for cells cultured on plastic substrata to 2.1 x 10(-3) mumoles/mg/min when gels were non-released, and 2.9 x 10(-3) mumoles/mg/min when gels were released after 12 days of culture. This was confirmed by electron microscopical visualization of alkaline phosphatase activity. Elevated levels of aminopeptidase activity were also observed on day 12 (plastic = 26 milliunits/mg; non-released gel = 41 milliunits/mg; released gel = 36 milliunits/mg). Similarly, changes occurred in the secretion of carcinoembryonic antigen from 0.96 x 10(-2) micrograms/mg/48 hours by cells cultured on plastic to 2.3 x 10(-2) micrograms/mg/48 hours by cells cultured on floating collagen gels. The effects of permitting HT-29 cells to undergo polarization were tested by culture on inert filter inserts: morphological features of intestinal differentiation were observed although this did not occur until after 21 days. These studies show that optimization of the growth conditions of anaplastic cells in vitro may provide cultures more representative of the tumor in vivo. This model system may be useful for cell biological and pharmacological studies of colon carcinoma.
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PMID:The influence of type I collagen on the growth and differentiation of the human colonic adenocarcinoma cell line HT-29 in vitro. 142 2

EDTA treatment of intestinal brush border membranes (BBM) and epithelial cell supernatant completely inhibited alkaline phosphatase (AP) activity in suckling rat intestine. AP activity was fully regained upon dialysis of the preparations against Zn2+ and to a lesser extent against Co2+, Ca2+ and Mn2+ ions. Other metal ions (Cd2+ and Mg2+) tested were essentially ineffective in restoring the enzyme activity. Considerable differences were observed in kinetic characteristics of the membrane-bound and soluble AP activities in response to various metal ions. There were apparent differences in Km, Vmax, energy of activation (Ea) and thermal stability of the soluble and membrane-bound AP activities, after metal ion substitutions. Nearly 35% AP activity was solubilized on sodium dodecyl sulphate treatment of brush borders (membrane protein: detergent ratio 1:3; w/w). Dialysis of detergent solubilized BBM against different metal ions reconstituted AP activity in the particulate fraction: the order of effectiveness was Zn greater than Ca greater than Mn greater than Co. The kinetic properties of the reconstituted AP were essentially similar to the non-integrated enzyme activity in response to various divalent metal ions examined. But there were apparent differences in Km, Vmax, Ea and thermal stability of the reconstituted AP activity compared to native brush border enzyme. The results suggest the unique requirement of Zn ions for stability and catalytic activity of the soluble and membrane-bound AP activity in suckling rat intestine.
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PMID:Effect of divalent metal ions on soluble and membrane-bound alkaline phosphatase activity in suckling rat intestine. 145 47

The expression and inducibility of cytochrome P450IA1 isozyme was investigated in the human carcinoma cell line Caco-2 cultured between days 7 and 35 in the absence or the presence of various enzyme inducers such as 3-methylcholanthrene, beta-naphthoflavone (beta NF), dioxin, isosafrole, rifampycin, dexamethasone or phenobarbital. 7-Ethoxyresorufin O-deethylase activity (EROD) was maximal at day 25 when the differentiation of Caco-2 cells, characterized by the level of the brush border associated enzymes such as sucrase isomaltase and alkaline phosphatase, was higher. The inducibility of this enzyme activity was found to be maximal when cells were treated between days 7 and 10. After a 3-day treatment of Caco-2 cells with 50 microM beta NF, EROD achieved 36.6 +/- 14.6 pmol/min/mg compared to 2.5 +/- 1.1 pmol/min/mg in untreated cells. This enzyme activity appeared to be supported only by P450IA1 isozyme because: 1) EROD was quantitatively inhibited by alpha-naphthoflavone, a P450IA1-specific inhibitor; otherwise, phenacetin O-deethylation was completely abolished in the presence of alpha-naphthoflavone and not by furafylline, a P450IA2-specific inhibitor; 2) EROD was induced after treatment with 3-methylcholanthrene, beta NF and dioxin, which are P450IA1 inducers, but not by isosafrole, a P450IA2-specific inducer; 3) cytochrome P450IA1 apoprotein could be immunodetected by antibodies directed against rabbit cytochrome P450-LM6, orthologous to P450IA1, in polycyclic hydrocarbon-treated cells; 4) under the latter conditions, P450IA1 mRNA accumulation was specifically detected, but not P450IA2 mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation of cytochrome P450IA1 gene expression in a human intestinal cell line, Caco-2. 146 46

The renal toxicity of harman and norharman, administered for 2 or 4 weeks at dietary levels of 1,000, 500, or 0 parts per million (ppm), was investigated in 6-week-old male F344/DuCrj rats. Although rats fed 1,000 ppm harman or norharman, but not the 500 ppm level, demonstrated marked body weight retardation from 1 week to termination, no mortalities occurred. Marked elevation of water consumption was evident in rats given harman or norharman at 1,000 ppm, but not at 500 ppm, together with large increases in urine of low specific gravity. Urinary lysosomal enzymes (N-acetyl-beta-D-glucosaminidase, NAG, and lactate dehydrogenase, LDH) and sugar levels were increased, and the brush border enzymes (gamma-glutamyl transpeptidase, GGT, and alkaline phosphatase, ALP) decreased. Furthermore, serum biochemistry revealed clear elevation of parameters indicating renal toxicity in these rats. Histopathologically, rats fed 1,000 ppm harman or norharman, but not 500 ppm, demonstrated focal toxic renal degenerative/necrotic and regenerative lesions in proximal, distal, and collecting tubules. These changes were associated with a clearly increased labeling index (LI) of the nuclei of renal tubular epithelial cells on immunohistochemical staining for 5-bromo-2'-deoxyuridine (BrdU). Chemical specific crystal formation within tubular lumina was evident in rats fed 1,000 ppm, but not 500 ppm, this being considered the cause of the renal tubular lesions. It was concluded that harman and norharman exert renal toxicity at the dietary level of 1,000 ppm, but not 500 ppm, in male F344 rats.
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PMID:Dose-dependent renal tubular toxicity of harman and norharman in male F344 rats. 147 80

Certain phosphonocarboxylate analogues of phosphate are known to inhibit Na(+)-phosphate (Pi) cotransport in renal brush border membrane (BBM), but previously tested potential inhibitors incorporating structurally versatile aryl functionality were inactive. In this work, a series of novel alpha-halogenated [(phenylphosphinyl)methyl]phosphonates [PhpXYMP: X, Y = H, F (2); F, F (3); H, Cl (6); Cl, Cl (4); H, Br (7); Br, Br (5); and Cl, Br (8)] were prepared via synthesis of the corresponding triethyl esters, acid hydrolysis, and isolation as pyridine salts. The compounds were evaluated as inhibitors of Na(+)-gradient-dependent 32Pi uptake by rat renal cortex BBM vesicles (BBMV) in vitro. The PhpFMP racemate 2 had higher activity (-49% delta inhibition) than other members of the series (-22 to -39% delta inhibition). pKa values of 1.5-2.0, 2.7, and 7.1 were estimated for 2 using a 31P delta vs pH plot, indicating that in the activity assays it exists as both dianion and trianion, with the latter form predominant. PhpFMP had no significant inhibitory effect on Na(+)-gradient-dependent uptake of D-glucose or L-proline in the same BBMV, and did not inhibit BBM alkaline phosphatase. Kinetic analysis showed that PhpFMP acts as a strictly competitive inhibitor of Na(+)-Pi cotransport with Ki = 0.358 +/- 0.021 mM (n = 3). The racemate 2 was resolved as its (-)-quinine salt into enantiopure (+)-2 [Na+ salt, [alpha]25D = +6 degrees (aqueous MeOH)] and a Na+ salt of 2 enriched in (-)-2. The two compounds did not differ significantly as inhibitors of Na(+)-gradient dependent 32Pi uptake by rat renal cortex BBM vesicles (BBMV) in vitro. The results are discussed in terms of structural requirements for inhibition.
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PMID:Alpha-halo [(phenylphosphinyl)methyl]phosphonates as specific inhibitors of Na(+)-gradient-dependent Na(+)-phosphate cotransport across renal brush border membrane. 147 88

The differentiation status of epithelial cells in intestinal adaptation remains unclear. To determine whether enterocytes reach optimum maturity following adaptation after 85% shortening of the rat gut by jejunoileal bypass surgery, activities of two brush border enzymatic markers of differentiation, alkaline phosphatase and sucrase, were examined in subpopulations of epithelial cells isolated sequentially from the villus/crypt axis of normal (sham operated) and hyperplastic mucosa. In jejunal villi, adaptational hyperplasia was associated with an increase in total epithelial alkaline phosphatase, but not total sucrase, activity; alkaline phosphatase activity increased most obviously in cells at the 11-50% position (from the tip) on villi. In hyperplastic ileal villi, total alkaline phosphatase activity fell, although sucrase activity did not change significantly. Specific activity (per mg protein) of sucrase on jejunal villus epithelium was reduced by the adaptational changes to bypass; alkaline phosphatase specific activity remained unchanged. In the ileum, despite adaptational changes to bypass, there was no increase in the normally low specific activities of sucrase and alkaline phosphatase. Bypass surgery did not change the major site of expression of either enzyme on jejunal or ileal villi. In conclusion, enzymatic markers of functional differentiation are not all equally affected by adaptational hyperplasia. Hypertrophy of villi and increased cell proliferation seen in jejunum remaining exposed to luminal contents resulted in an increase in the alkaline phosphatase but not the sucrase content. This is not, therefore, the result of a simple immaturity of villus cells. Morphological adaptation in the ileum, however, is not accompanied by adaptation of brush border enzyme markers of differentiation, confirming a functional immaturity of these cells. Strategies for increasing the expression of these markers may have clinical value.
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PMID:Differentiation status of rat enterocytes after intestinal adaptation to jejunoileal bypass. 148 65

Mice fed on an 8% protein (low-protein; LP) diet for 21 days exhibited a significant (p less than 0.001) decrease in their body weights compared with the pair-fed controls (18% protein). Brush border enzyme analysis revealed a 56% increase in sucrase activity and a significant decrease in alkaline phosphatase (p less than 0.05), beta-D-glucosidase (p less than 0.001) and beta-D-galactosidase (p less than 0.05) activities in protein-deficient mice. Lactase activity was unaltered in these conditions. Hexose and hexosamine contents of the brush border membranes (BBM) decreased considerably as a result of the LP diet. Protein deprivation significantly enhanced (p less than 0.01) brush border sialic acid and reduced (p less than 0.05) fucose content compared to the controls. The binding of 125I-labelled wheat germ agglutinin and Ulex europaeus agglutinin I to BBM was in agreement with the data on sialic acid and fucose levels of the membranes. The binding of peanut agglutinin to BBM was 38% higher in LP-diet-fed animals. The incorporation of [14C]mannose and [14C]glucosamine into BBM was markedly reduced (25%), while that of [3H]fucose was apparently unaffected. These results suggest that the feeding of an LP diet to mice results in marked alterations in the intestinal epithelial cell surface glycosylation.
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PMID:Intestinal epithelial cell surface glycosylation in mice. 1. Effect of low-protein diet. 151 Mar 49

The size of the renal sodium/phosphate symporter was estimated with the radiation inactivation technique in isolated bovine brush border membrane vesicles and after reconstitution in proteoliposomes. The functional unit of the native phosphate carrier had a radiation inactivation size of 172 +/- 17 kDa. Identical values were obtained for the reconstituted carrier whether it was irradiated before or after the formation of the proteoliposomes (161 +/- 9 and 159 +/- 11 kDa, respectively). The sodium-independent uptake of phosphate was not affected significantly by radiation doses up to 10 Mrad. This activity is therefore not due to the reconstitution of a large phosphate-binding protein such as alkaline phosphatase. Furthermore, bromotetramisole, a specific inhibitor of phosphate binding to this enzyme, had no significant effect on the uptake of phosphate by the proteoliposomes.
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PMID:Molecular size of the renal sodium/phosphate symporter in native and reconstituted systems. 155 Aug 40

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 in vitro effect of butyrate on expression of differentiation markers in colonic epithelial cells was assessed in the colon cancer cell line, LIM1215 and in epithelial cells isolated from a surgically resected histologically normal colon. Markers used to assess cell differentiation were: net glycoprotein synthesis ([3H]-glucosamine uptake) expressed relative to net protein synthesis ([14C]-leucine uptake), and the expression of the brush border glycoproteins (alkaline phosphatase and carcino-embryonic antigen) in cell homogenates calculated relative to cellular protein content. In response to 24 h exposure to 1 mmol/L butyrate, all markers significantly increased in LIM1215 cells whereas they all significantly decreased in isolated colonic epithelial cells under identical culture conditions. Similar effects were seen at butyrate concentrations of up to 4 mmol/L. Butyrate suppressed proliferation of LIM1215 cells but had no consistent effect on [3H]-thymidine uptake by, or DNA content of, normal epithelial cells. Additional experiments found no evidence of a toxic effect of butyrate at those concentrations nor of an alteration of cell responsiveness to butyrate due to the isolation process itself. In contrast to its differentiative effect on neoplastic cells, butyrate reduces the expression of phenotypic markers of differentiation in vitro in colonic epithelial cells from non-neoplastic mucosa.
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PMID:Contrasting effects of butyrate on the expression of phenotypic markers of differentiation in neoplastic and non-neoplastic colonic epithelial cells in vitro. 157 99


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