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At least 1,243 records · Page 69Linked to original sources
PubMed1988

Evidence for the expression of a primitive intestinal-like alkaline phosphatase in the intestinal 407 cell line.

Intestinal-like alkaline phosphatase was found to be expressed in the intestinal 407 cell line. This enzyme was identified by use of monoclonal antibodies specific for human placental (H7 and HPMS-1) and intestinal alkaline phosphatase (2HIMS-1 and 2HIMS-3) separately. Purification of this isozyme by use of two different monoclonal antibody immunoaffinity chromatographies demonstrates a single protein band on SDS-polyacrylamide gel electrophoresis indicating that this enzyme is not formed as a heterodimer. The apparent monomer subunit molecular weight and the dimer molecular weight of this isozyme were determined to 70000 and 160000, respectively. The enzyme is a homodimer according to molecular weight determinations. Furthermore, this isozyme is neuraminidase sensitive and comparatively heat stable, properties also characteristic for the placental enzyme. Our data suggest that the intestinal-like alkaline phosphatase in the intestinal 407 cell line displays properties intermediate of the intestinal and placental isozymes which may reflect the existence and reexpression of a new primitive isozyme.

Alkaline Phosphatase↗
PubMed2003

Identification of a regulated alkaline phosphatase, a cell surface-associated lipoprotein, in Mycobacterium smegmatis.

Although alkaline phosphatases are common in a wide variety of bacteria, there has been no prior evidence for alkaline phosphatases in Mycobacterium smegmatis. Here we report that transposon insertions in the pst operon, encoding homologues of an inorganic phosphate transporter, leads to constitutive expression of a protein with alkaline phosphatase activity. DNA sequence analysis revealed that M. smegmatis does indeed have a phoA gene that shows high homology to other phoA genes. The M. smegmatis phoA gene was shown to be induced by phosphate starvation and thus negatively regulated by the pst operon. Interestingly, the putative M. smegmatis PhoA has a hydrophobic N-terminal domain which resembles a lipoprotein signal sequence. The M. smegmatis PhoA was demonstrated to be an exported protein associated with the cell surface. Furthermore, immunoprecipitation of PhoA from [(14)C]acetate-labeled M. smegmatis cell lysates demonstrated that this phosphatase is a lipoprotein.

Alkaline Phosphatase↗
PubMed1984

Subcellular localization of alkaline phosphatase in Bacillus licheniformis 749/C by immunoelectron microscopy with colloidal gold.

Subcellular distribution of the alkaline phosphatase of Bacillus licheniformis 749/C was determined by an immunoelectron microscopy method. Anti-alkaline phosphatase antibody labeled with 15- to 18-nm colloidal gold particles (gold-immunoglobulin G [IgG] complex) were used for the study. Both the plasma membrane and cytoplasmic material were labeled with the gold-IgG particles. These particles formed clusters in association with the plasma membrane; in contrast, in the cytoplasm the particles were largely dispersed, and only a few clusters were found. The gold-IgG binding was quantitatively estimated by stereological analysis of labeled, frozen thin sections. This estimation of a variety of control samples showed that the labeling was specific for the alkaline phosphatase. Cluster formation of the gold-IgG particles in association with the plasma membrane suggests that existence of specific alkaline phosphatase binding sites (receptors) in the plasma membrane of B. licheniformis 749/C.

Alkaline Phosphatase↗
PubMed1977

Serum alkaline phosphatase isoenzyme patterns in patients with chronic renal failure.

1. Using acrylamide gel electrophoresis the serum alkaline phosphatase (ALP) isoenzyme patterns of 204 patients with chronic renal failure have been examined for periods up to 18 months in length. 2. Of those with elevated serum ALP activity the bone isoenzyme was largely responsible. The presence of increasing amounts of the bone isoenzyme even if the total serum ALP activity remains within the normal reference range should also indicate bone pathology. 3. Intestinal alkaline phosphatase was the major serum alkaline phosphatase in 15% of patients on regular haemodialysis and 10% of uraemic patients not on dialysis. The overall incidence of detectable intestinal alkaline phosphatase in those with normal serum ALP activity was 36%. 4. With those patients whose serum ALP activity changed significantly during the investigation this usually reflected changes in the amount of the bone isoenzyme. Patients with abnormal amounts of the intestinal isoenzymes in their serum usually showed little variation in serum ALP activity over the period of the study.

Alkaline Phosphatase↗
PubMed2004

Induction of alkaline phosphatase in the inflamed intestine: a novel pharmacological target for inflammatory bowel disease.

This study demonstrates the upregulation of alkaline phosphatase and the mechanisms involved in experimental colitis. All models of ileal and colonic inflammation examined, which were characterized by significant oxidative stress and neutrophil infiltration, resulted in an increase in alkaline phosphatase activity which was attributable to both epithelial cells and cells of the lamina propria, mainly leukocytes. The increase in alkaline phosphatase sensitivity to the inhibitors levamisole and homoarginine, together with changes in the apparent molecular size and in the sialization of the enzyme, indicated a change in the isoform expressed. An increase in tissue non-specific alkaline phosphatase expression was observed by Western blotting. Treatment with the bone/kidney alkaline phosphatase inhibitor levamisole or a monoclonal antibody resulted in significant protection from colonic inflammation. Taken together, these results indicate that the kidney isoform is a marker of intestinal inflammation and that it might even constitute a target for pharmacological intervention.

Alkaline Phosphatase↗
PubMed1981

The use of potent inhibitors of alkaline phosphatase to investigate the role of the enzyme in intestinal transport of inorganic phosphate.

In an investigation of the link between Pi transport and alkaline phosphatase in mammalian small intestine, the characteristics of Pi uptake by brush-border membrane vesicles prepared from rat intestine were compared with the properties of the tissue alkaline phosphatase. The NaCl-dependent Pi uptake had a Km of 0.1 mM at pH 7.5 and was inhibited totally by 1 mM-arsenate and by 1 mM-vanadate. These compounds are also potent competitive inhibitors of the alkaline phosphatase activity of the vesicles, with Ki values less than 5 microM at pH 7.5. When the effect on Pi uptake of several other potent inhibitors of alkaline phosphatase, including phosphonates and phosphate analogues, was tested, however, it was found that there was little, if any, inhibition of transport under conditions in which the inhibition of phosphatase activity was total. Incubation of the vesicles for 20 min with oxidized adenosine 5'-[beta gamma-imido]triphosphate followed by rapid gel filtration to remove the inhibitor resulted in an irreversible loss of phosphatase activity, but left Pi transport unimpaired. Conversely, a similar prolonged incubation with adenosine 5'-[beta-thio]diphosphate or adenosine 5'-[gamma-thio]triphosphate had no effect on alkaline phosphatase activity but resulted in a permanent partial loss of transport capability. The failure to demonstrate an inhibition of Pi transport resulting from inhibition of alkaline phosphatase and the different responses of enzymic activity and Pi transport to irreversible inhibition make it very unlikely that the enzyme is directly involved in the transport system.

Adenine Nucleotides↗
PubMed1996

Measurement of bone specific alkaline phosphatase in the horse: a comparison of two techniques.

For many years total alkaline phosphatase (AP) activity in serum has been used to monitor bone metabolism in different species. However, total AP lacks bone specificity because the total activity in serum is made up of several isoenzymes, of which the liver and bone isoforms predominate. The aim of the present study was to evaluate an immunoradiometric assay for measuring bone specific alkaline phosphatase (BAP) in horses. BAP, a specific marker of bone formation, was measured in sera from thoroughbred horses by using a previously characterised wheat germ lectin (WGL) precipitation assay and an immunoradiometric assay. The levels of immunoreactive BAP (iBAP) and WGL precipitated BAP (wBAP) were related to the serum levels of total AP and another marker of bone formation, the carboxy-terminal propeptide of type 1 collagen (PICP). In horses over one year old, iBAP correlated at least as strongly with total AP as with wBAP, which suggests that the immunoradiometric assay may partially cross-react with liver alkaline phosphatase in horse serum. This possibility was supported by the observation that there was a weaker correlation between iBAP and PICP than between wBAP and PICP. These data indicate that WGL precipitation is currently the most specific method for measuring bone specific alkaline phosphatase in horses.

Aging↗
PubMed1984

Immunochemical data suggesting a pattern for the evolution of human placental alkaline phosphatase.

Hyperimmune absorbed rabbit antisera which were reactive with epitopes specific for individual variants of human placental alkaline phosphatase were tested for their reactivity with primate placental alkaline phosphatases. Using the three epitope-specific reactivities defined previously, we found that: epitope I is present in the S-, D- and I-variants of human placental phosphatase, and in the chimpanzee and pygmy chimpanzee placentae; epitope II is present in the F- and 17-variants, and in the Nagao isoenzyme of human placental alkaline phosphatase, and in some orangutan placentae and all spider monkey placentae tested; epitope III is present in the F- and 17-variants, and the Nagao isoenzyme of human placental alkaline phosphatase, and in all the spider monkey placentae and the single squirrel monkey placenta examined. The binding assay was complemented by a competitive radioimmunoassay, which confirmed that the spider monkey placental samples were binding to the same antibody population which bound the human enzymes. The presence of epitopes characteristic of rare human placental phosphatase variants in these remote primate relatives suggests that the rare variants in the current human population have been present during the entire course of evolution. The presence of both epitopes characteristic of the Nagao isoenzyme in spider monkeys suggests that this variant isoenzyme is closely related to the enzyme present in the primate placenta at the time of species divergence (humans and New World monkeys). A hypothetical scheme for this divergence is proposed.

Alkaline Phosphatase↗
PubMed1992

Detection of mRNA by in situ hybridisation and in northern blot analysis using oligodeoxynucleotide probes labelled with alkaline phosphatase.

AIMS: To assess whether a reduction in intensity of signal observed using an alkaline phosphatase labelled oligodeoxynucleotide probe could be explained on the basis of procedural steps rather than reduced sensitivity. METHOD: Signal intensity was assessed on in situ hybridisation for pro-opiomelanocortin (POMC) mRNA in rat pituitary and for somatostatin mRNA in human pancreas and in northern blot analysis for POMC mRNA in the presence and absence of formamide. The direct effects of formamide on the alkaline phosphatase detection step were assessed using histochemical enzyme detection in rat kidney. RESULTS: All signals were reduced in systems containing formamide. CONCLUSIONS: In the absence of formamide clear, strong signals for specific mRNAs can be obtained by in situ hybridisation and northern blot analysis using oligodeoxynucleotide probes directly labelled with alkaline phosphatase. Formamide seems to inhibit the activity of alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1982

Alkaline phosphatase activity in cultured meningioma cells.

The specific activity of alkaline phosphatase in cultured human meningioma cells varies over a relatively wide range. There is no correlation between the levels of activity and the histological type of meningioma from which the cultures were derived. The enzyme is heat-labile and is strongly inhibited by L-homoarginine, levamisole, and 1-bromotetramisole, but unaffected by L-phenylalanine and L-phenylalanyl-glycylglycine. These findings indicate that meningioma cells synthesize the liver/bone/kidney form of alkaline phosphatase. In contrast to cultures derived from pituitary adenomas, glioblastomas, and astrocytomas in which prednisolone and/or sodium butyrate elicit a manifold increase of alkaline phosphatase activity, with meningioma cells the hormone causes only a slight augmentation in specific activity, and the fatty acid is ineffective. As with other cells producing the liver/bone/kidney enzyme form, no increase in activity occurs in meningioma cells growing in hyperosmolar medium.

Alkaline Phosphatase↗
PubMed1976

Bromodeoxyuridine induced variations in the level of alkaline phosphatase in several human heteroploid cell lines.

The level of alkaline phosphatase in a number of established cell lines of human origin can be modified by exposure to non-lethal concentrations of bromodeoxyuridine (BRdU). In the several cell lines examined an inverse relationship between amount of induction and constitutive level of the enzyme was observed. Thus, the H.Ep 2 line, which had the highest basal level of enzyme, was reversibly repressed following exposure to the drug, whereas other cell lines with relatively low constitutive enzyme levels were induced to a maximum of 10-fold following exposure. Initiation of induction required from 24 to 48 hours, and as short an exposure ("pulse") as five hours was sufficient to produce induction. Exposure to visible light had no effect upon the repression of alkaline phosphatase in H.Ep 2 by BRdU. Induction did not occur in non-dividing, serum starved cells. The time course of induction by BRdU and hydrocortisone was similar, and simultaneous exposure of the cells to both agents resulted in no greater induction than that observed with either drug alone. Experiments utilizing mitomycin C yielded significant induction in the presence of this agent alone, and somewhat less induction when both mitomycin C and BRdU were added simultaneously. These results suggest that DNA synthesis is required for BRdU were added simultaneously. These results suggest that DNA synthesis is required for BRdU-mediated induction of alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1977

Clinical usefulness of alkaline phosphatase isoenzyme determinations.

1. We report on the clinical usefulness of alkaline phosphatase isoenzyme determinations using a combined chemical inhibition method on 731 patient serum specimens exhibiting elevated (greater than 350 U/L) alkaline phosphatase (AP) activity. 2. The relative percentages of the organ-specific alkaline phosphatase activities were computed on the basis of three independent assays: total activity, activity in the presence of 10 mMl-phenylalanine, and activity in the presence of 3.1 M urea. 3. Gamma-glutamyl transferase (GGT) activity assays were also performed on the same specimens. Using an upper reference limit of 30 U/L for GGT and comparing the GGT results with the percent liver AP, we found that the GGT results were 91% sensitive and 60% specific. 4. We conclude that AP isoenzyme determinations are very useful in identifying the organ source(s) responsible for elevated AP values. 5. The reference ranges for several age groups in relation to the adult population and their significance are presented.

Adolescent↗
PubMed1982

Membrane-associated alkaline phosphatase from Bacillus licheniformis that requires detergent for solubilization: lactoperoxidase 125I localization and molecular weight determination.

When membranes of Bacillus licheniformis MC14 were extracted exhaustively with 1 M magnesium, approximately 80% of the membrane-associated alkaline phosphatase (orthophosphoric-monoester phosphohydrolase [alkaline optimum], E.C. 3.1.3.1) was solubilized. The remaining activity could be extracted with a cationic detergent, hexadecylpyridinium chloride, without loss of enzymatic activity. The detergent-extractable alkaline phosphatase was immunoprecipitable with antibody to the salt-extractable alkaline phosphatase or the secreted alkaline phosphatase, had an approximate molecular weight of 60,000, and was localized 100% on the outer surface of the cytoplasmic membrane.

Alkaline Phosphatase↗
PubMed1990

Estrogen regulation of placental alkaline phosphatase gene expression in a human endometrial adenocarcinoma cell line.

A human endometrial tumor (Ishikawa) cell line in culture responded to estradiol stimulation, as measured by growth and alkaline phosphatase activity. These effects were similar whether the medium was enriched with serum or was serum-free. Estradiol increased placental alkaline phosphatase activity 2-3-fold over control in these Ishikawa cells. The mechanism for this increase appeared to be at the level of transcription, at least in part, since there was an increase in the concentration of placental alkaline phosphatase mRNA. The administration of tamoxifen or 4-hydroxytamoxifen was unable to antagonize the estradiol-stimulated alkaline phosphatase enzyme activity or mRNA expression. The administration of tamoxifen alone had no effect on alkaline phosphatase enzyme activity, but tamoxifen did stimulate the steady state concentration of alkaline phosphatase mRNA. In contrast, a new antiestrogen, ICI 164,384, was able to antagonize both of these estradiol-stimulated effects.

Adenocarcinoma↗
PubMedDate not supplied

Histochemical localization of alkaline phosphatase in the uterus of rats: response to a few indigenous plant extracts.

Localization of alkaline phosphatase in the uterine luminal and glandular epithelium of rats under the influence of 50% ethanolic and benzene extracts of three indigenous plants viz. Embelia ribes Burm. (dried berries), Artobotrys odoratissimus Linn. (fresh green leaves) and Hibiscus rosasinensis Linn. (flowers) has been studied histochemically. 75 and 150 mg/kg doses of 50% ethanolic extracts of E. ribes increased the intensity of reaction for alkaline phosphatase in both luminal and glandular epithelium, whereas extracts of A. odorantissimus and H. rosa-sinensis could not elicit any significant positive staining in luminal and glandular epithelium for alkaline phosphatase. Intense positive reaction for alkaline phosphatase due to E. ribes extract has been correlated with its estrogenic mode of action.

Alkaline Phosphatase↗
PubMed1993

Plasma bone-specific alkaline phosphatase as an indicator of osteoblastic activity.

The total plasma alkaline phosphatase level has long been recognised as an indicator of osteoblastic activity, but lack of specificity makes it an insensitive index of the progress of disease and the response to treatment. Selective precipitation by wheatgerm lectin allows measurement of the plasma bone-specific alkaline phosphatase. We measured the plasma levels of this isoenzyme in 170 normal Chinese adolescents and adults, in 49 adults with fractures of a long bone, in 15 patients with osteosarcoma and in 38 patients with osteolytic metastases. The enzyme activity was also determined in 39 patients with liver disease. Of the patients with fractures, 94% had increased plasma activity during the healing process. The level was also increased in those with osteosarcoma but not in those with osteolytic bone metastases. There was no significant increase in activity in the patients with liver disease. We conclude that the plasma bone-specific alkaline phosphatase activity is a sensitive and reliable measure of osteoblastic activity.

Adolescent↗
PubMed1979

Potential inhibitors of rat tooth alkaline phosphatase studied by means of different histochemical techniques.

Two histochemical methods for demonstration of alkaline phosphatase activity, a lead pyrophosphate- anda naphtholphosphate technique, were compared. Since different results may be due to methodological differences as well as different enzyme activities, the enzymatic hydrolysis of the naphtholphosphate was visualized both by means of an azo-dye coupler and by lead-capturing of the liberated phosphate ion. Various potential inhibitors of alkaline phosphatase activity (diphosphonate, D-penicillamine, and sodium fluoride) were also tested. The use of diphosphonate and D-penicillamine resulted in inhibited or reduced staining, which could mainly be explained by an interference by these compounds with components in the incubation media rather than with the enzyme itself. The addition of sodium fluoride had no effect on the naphtholphosphate staining pattern irrespective of capturing method, whereas the odontoblastic pyrophosphate splitting alkaline phosphatase appeared to be sensitive to sodium fluoride, suggesting the presence of two alkaline phosphatases in odontoblasts.

Alkaline Phosphatase↗
PubMed1990

Effect of membrane moiety and magnesium ions on the inhibition of matrix-induced alkaline phosphatase by zinc ions.

1. The inhibition of matrix-induced alkaline phosphatase by zinc ions is due to the displacement of magnesium ions from its binding site. 2. Binding of magnesium ions to alkaline phosphatase induces conformational changes which activate the enzyme. 3. Binding of zinc ions to alkaline phosphatase induces conformational changes which impair the catalytic action of the enzyme. 4. The inhibition of the enzyme by zinc ions is affected by membrane environment and magnesium ions.

Alkaline Phosphatase↗