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At least 1,477 records · Page 82Linked to original sources
PubMed1977

The mechanism of action of citrinin on rabbit kidney alkaline phosphatase activity in vivo.

The effect of citrinin poisoning on rabbit kidney alkaline phosphatase was investigated. After seven days administration of citrinin (2 mg/kg body weight daily) the animals were sacrificed and the level of enzymes estimated in serum and kidney. Serum enzymes showed no variation in activity in the citrinin-treated animals, but in kidney, alkaline phosphatase activity decreased significantly. The decreased activity was mainly associated with the cytoplasmic fraction and in fractions Ib and II. The enzyme II obtained from citrinin-treated animal showed no kinetic difference in substrate specificity, inhibition by phenylalanine, phosphate, sodium-EDTA and Zn2+ ions, activation by Mg2+ ions, thermal inactivation and electrophoretic mobility to that of control Enzyme II. Immunological studies showed that the decrease in enzyme activity was due to existence of inactive enzyme protein. Hormones like cyclic AMP, prostaglandin E1 and parathyroid hormone reversed the decreased enzyme activity due to citrinin poisoning in mouse and rabbit. This study favours the possible existence of active and inactive forms of alkaline phosphatase in the system.

Alkaline Phosphatase↗
PubMed1988

Acid and alkaline phosphatase activity in bone-cyst fluid.

The acid and alkaline phosphatase activity in fluid aspirated from solitary bone cysts in six patients was measured, and large increases in the concentration of acid phosphatase were found. In some cases this increase was reflected in venous blood concentrations. The significance of these findings for the pathogenesis and the management of solitary bone cyst is discussed.

Acid Phosphatase↗
PubMed2006

[High serum alkaline phosphatase level revealing a liver adenoma].

A 25-year-old woman had a high serum level of alkaline phosphatase activity (2571 UI/L). Serum levels of transaminases, gamma glutamyl transferase and bilirubin were normal. Abdominal ultrasonography revealed a tumor nodule in the right liver lobe. There was no evidence of biliary obstruction. The serum activity of alkaline phosphatase returned to normal after surgical removal of the liver tumor. Histologic examination showed that the tumor was a liver adenoma with no evidence of degeneration. The adenoma cells reacted strongly positive to alkaline phosphatase by histochemical staining. The production of hepatic and biliary type alkaline phosphatase by the tumor is the most likely mechanism for the high serum levels observed in this patient.

Adenoma↗
PubMed1991

Gly429 is the major determinant of uncompetitive inhibition of human germ cell alkaline phosphatase by L-leucine.

The catalytic activity of human placental alkaline phosphatase (PLAP) and germ cell alkaline phosphatase (GCAP) can be inhibited, through an uncompetitive mechanism, by L-Phe. GCAP is also selectively inhibited by L-Leu. Site-directed mutagenesis of five of the 12 residues which are different in PLAP and GCAP revealed that Gly429 is the primary determinant of GCAP inhibition by L-Leu, and Ser84 and Leu297 play a modulatory role in the inhibition.

Alkaline Phosphatase↗
PubMed1976

Changes in alkaline phosphatase activity in periosteal cells in healing fractures.

The quantitative changes in alkaline phosphatase activity in the periosteal cells close to the fracture in rat metatarsal bones has been measured during the first 5 days postfracture. This study has been made possible by two technological advances, firstly the development of cryostat microtomy for cutting unfixed, undemineralised bone, and secondly the use of scanning and integrating microdensitometry for quantifying the activity in each periosteal cell. The results showed a loss of alkaline phosphatase activity close to the fracture site, with activity rising to normal values 0.8-1.0 mm from the site. No alkaline phosphatase activity was found in the cells which proliferated from the periosteum. It is suggested that reduced glutathione could cause such inhibition.

Alkaline Phosphatase↗
PubMed1985

Human placental alkaline phosphatase in benign and malignant ovarian neoplasia.

In benign and malignant ovarian tumor patients, human placental alkaline phosphatase (HPLAP) was determined in serum and extracts from surgical tumor biopsies using a highly specific enzyme-antigen immunoassay based on a mouse monoclonal antibody (E6) to HPLAP. Serum HPLAP levels greater than or equal to 0.1 unit/liter were found in 58% of ovarian cancer patients. Serum carcinoembryonic antigen levels were positive (greater than 5.4 ng/ml) in 17% of these patients. HPLAP was detected in extracts from 13 of the 14 tumors investigated (range, 2.4 to 557 milliunits/g). Only the mixed heterologous Müllerian sarcoma was negative. The highest HPLAP content of normal ovarian tissue was 1.1 milliunits/g. The amount of heat-stable and L-p-bromotetramisole-insensitive alkaline phosphatase was in all cases much higher than the fraction recognized by E6. The neoplastic origin of HPLAP was confirmed immunohistochemically on paraffin sections by an indirect avidin-biotin-peroxidase staining procedure using E6. The staining pattern was compared to the histochemical distribution of total alkaline phosphatase on adjacent sections. A consistency was found between the amount of HPLAP in tissue extracts and its immunohistochemical distribution. In all the tumors, staining for HPLAP was observed mainly on the plasma membranes of carcinoma cells. In 9 of the 10 carcinomas, the histological distribution of HPLAP and also of total alkaline phosphatase was heterogeneous. HPLAP staining, present in one of five normal ovaries, was restricted to germinal inclusion cysts. The present results support the hypothesis that serous ovarian tumors originate from these cysts.

Alkaline Phosphatase↗
PubMed1985

Tetrameric alkaline phosphatase in human liver plasma membranes.

Molecular weights of native membrane-bound alkaline phosphatase released by butanol and by nonionic detergents were more than twice that of the purified dimeric enzyme. Alkaline phosphatase released by phosphatidylinositol-specific phospholipase-C was of both high and low molecular weight: the former was a protomer of a single protein of the same molecular size as monomeric alkaline phosphatase. We conclude that the membrane-bound enzyme is probably a tetramer.

Alkaline Phosphatase↗
PubMed1976

Distribution of alkaline phosphatase in the microcirculatory pathways of the coronary system.

By histochemistry alkaline-phosphatase-activity in the microcirculatory pathways of the coronary vascular system were investigated. In the capillary network paralleling the myocardial fibers enzyme activity was found positive whereas in the large sinusoidal, endothelial vessels, linking transmurally neighbouring capillaries, there was no alkaline phosphatase activity. In both endothelial cell types, in capillaries and in sinusoids, a transendothelial vesicular thorotrast transport could be shown. It is supposed that the sinusoidal vessels preponderantly have to cope with intercapillary shear stress. Their nutritial function is believed to be of less importance. At least the lack of alkaline phosphatase activity should indicate that there is no selective transendothelial transport in the wall of these sinusoids.

Alkaline Phosphatase↗
PubMed1981

Intracellular alkaline phosphatase activity in cultured human cancer cells.

The effect of saponin treatment in demonstrating intracellular portion of alkaline phosphatase activity in human cancer cell lines was evaluated. Previous reports using standard lead-salt techniques visualized enzyme almost exclusively on the plasma membrane and sometimes in the lysosomes. However, by treating cells with saponin before or during the cytochemical incubation, intracellular alkaline phosphatase became demonstrable at the endoplasmic reticulum. Golgi apparatus, Golgi-derived vesicles and mitochondria as well as lysosomes and plasma membrane. These intracellular catalytic activities were significantly inhibited by the specific amino acid inhibitors characteristic for each cell line, and this suggested that intracellular alkaline phosphatase is the same isoenzyme as that present in the plasma membrane. The results of our current and previous studies therefore indicate that saponin reveals latent intracellular alkaline phosphatase activity by changing the membrane's physical state; thereby increasing the availability of both catalytic and antigenic sites of the enzyme to substrate and to antibody respectively.

Alkaline Phosphatase↗
PubMed1996

Microheterogeneity of the hydrophobic and hydrophilic part of the glycosylphosphatidylinositol anchor of alkaline phosphatase from calf intestine.

Digestion of calf intestine alkaline phosphatase with pronase and subsequent dephosphorylation of the released peptidyl-(Etn-P)2-glycosyl-PtdIns with HF generated 8 glycosyl-Ins species the largest of which (G1 and G2) have the following proposed structures: [sequence: see text] G3 and G5 are lower homologues of G1 and G2, respectively, being one alpha 1-2 linked mannopyranosyl residue shorter. G4 is analogous to G2 lacking the N-acetylgalactosaminyl residue and G6 is the next lower homologue of G4. Most of G4 and G6 occur substituted with a palmitoyl (G4, G6) or a myristoyl residue (G6) probably attached to the inositol moiety. Thus, the basic ManxGlc-Ins species are either substituted with an N-acetylgalactosaminyl residue or a fatty acid ester. The structures were deduced from compositional analysis, molecular-mass determination by matrix-assisted laser desorption MS, sequential hydrolysis with appropriate exoglycosidases and treatment with CrO3. Purification of the glycosylinositol species was achieved by a novel reverse-phase HPLC technique using fluorescent fluoren-9-yl-methoxy-carbonyl (Fmoc) derivatives. These stable derivatives were susceptible to hydrolysis with exoglycosidases which allowed sequential cleavages to be carried out and kinetics to be followed at the picomole level. We observed recently that native alkaline phosphatase separates on octyl-Sepharose into four distinct fractions of increasing hydrophobicity (F1-F4). Here we show that all four fractions contain G1-G6. The acylated species G4 and G6 were restricted to F2 and F4 which had been shown earlier to contain, on average, 2.5 and 3 fatty acid residues/subunit, respectively. In all four fractions the diradylglycerol moiety was predominantly diacylglycerol, alkylacylglycerol being less than 10% which is in contrast to most glycosyl-PtdIns--anchored proteins of mammalian origin.

Acetylgalactosamine↗
PubMed1985

Characterization of alkaline phosphatase in human urinary bladder carcinoma cell lines and enzyme regulation with prednisolone or sodium chloride.

In order to characterize newly established human urinary bladder carcinoma cell lines (JTC-29, JTC-30, JTC-31, JTC-32, JTC-33 and JTC-34) by Kakuya et al. [In Vitro, 19, 591-599 (1983)], we investigated alkaline phosphatase in these cell lines. Relatively high alkaline phosphatase activity was found in JTC-29 and JTC-32 cells, but the enzyme activity in the other cell lines was very low. Prednisolone induced alkaline phosphatase activity even at 0.005 micrograms/ml (14 nM) and the effect was maximal at 0.05 micrograms/ml. NaCl also induced alkaline phosphatase activity at 50 mM. A further increase in the activity was observed at 0.1 M NaCl, but at 0.2 M all cells came off from plastic culture dishes without an increase in the enzyme activity during the incubation for 24 h at 37 degrees C. Both actinomycin D and cycloheximide abolished the increases in the enzyme activity with prednisolone or NaCl. The Lineweaver-Burk plot showed that the increases in the enzyme activity are due to the increases in Vmax, but not in Km. Alkaline phosphatase in JTC-32 cells and prednisolone-treated JTC-32 cells was heat stable and 100% of the initial enzyme activity remained after 30 min of incubation at 56 degrees C. However, the enzyme in JTC-29 cells was heat labile and its activity was reduced to less than 50% after 20 min of incubation at 56 degrees C. L-Phenylalanine was the strongest inhibitor for the enzyme reactions in JTC-32 cell homogenates among L-phenylalanine, L-leucine and L-homoarginine, whereas L-homoarginine was the strongest for the enzyme reactions in JTC-29 cell homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1991

Alkaline phosphatase activity in human and rat liver tumors.

Enzyme activity measurements of alkaline phosphatase in surgically removed human liver tumors showed elevated level of the enzyme in 6 focal nodular hyperplasias, reduction in 8 primary hepatocellular carcinomas, and no change in the 4 adenoma samples. The activity represented liver type of alkaline phosphatase nearly in all cases because it could be inhibited by L-homoarginine more extensively than by L- phenylalanine. Studies on polyacrylamide gel electrophoresis indicated the presence of a variant type isoenzyme only in one focal nodular hyperplasia and in two hepatocellular carcinomas, one of which showed a fibrolamellar structure whereas the other was associated to cirrhosis. The importance of the elevated amount of connective tissue in the tumor, resulting in an isoenzyme shift of alkaline phosphatase, received substantial support upon comparing chemically induced rat liver tumors with and without cirrhosis.

Alkaline Phosphatase↗
PubMed1987

Differential expression of alkaline phosphatase and ATPase activities in human colon carcinoma cell line HT-29.18 during differentiation.

The expression and cytochemical localization of alkaline phosphatase and Na+-pump sites were investigated in the human adenocarcinoma cell line HT-29.18 during differentiation. In the undifferentiated state, HT-29.18 cells expressed ATPase activity on plasma membrane whereas they displayed no alkaline phosphatase activity. In differentiated HT-29.18 cells, strong alkaline phosphatase activity was present on the apical membrane, whereas ATPase activity was restricted to the basolateral membrane. Intra- and intercellular lumina (cysts) observed in undifferentiated cells were devoid of both enzyme activities. In differentiated cells, cysts bearing well developed microvilli were strongly positive for alkaline phosphatase activity, while this activity seemed to be lacking in cysts without microvilli. ATPase activity was not found in either type of structure. Finally, HT-29.18 differentiated cells expressed, at pH 9.0, a p-nitrophenylphosphatase activity six-fold greater than that of undifferentiated cells.

Adenocarcinoma↗
PubMed1981

[Leucocyte alkaline phosphatase in normal and pathological pregnancy (author's transl)].

The activities of leucocyte alkaline phosphatase were determined in 511 patients with normal and pathological pregnancy. Mean values were compared and the enzyme followed up, and the conclusion was drawn that leucocyte alkaline phosphatase was no safe indicator of foetal condition. No direct relationship were found to exist between leucocyte alkaline phosphatase, total oestrogens, HSAP, HLAP, HPL, and oxytocinase.

Alkaline Phosphatase↗
PubMed1979

Phosphoester specificity of purified human liver alkaline phosphatase.

Kinetic parameters for the hydrolysis of a number of physiologically important phosphoesters by purified human liver alkaline phosphatase have been determined. The enzyme was studied at pH values of 7.0 to 10.0. The affinity of the enzyme for the compounds was determined by competition experiments and by their direct employment as substrates. Phosphodiesters and phosphonates were not hydrolysed but the latter were inhibitors. Calcium and magnesium ions inhibited the hydrolysis of ATP and PP1 and evidence is presented to show that the metal complexes of these substrates are not hydrolysed by alkaline phosphatase. A calcium-stimulated ATPase activity could not be demonstrated for the purified enzyme or the enzyme in the presence of a calcium-dependent regulator protein. Nevertheless, the influence of magnesium and calcium ions on the ATPase activity of alkaline phosphatase means that precautions must be taken when assaying for Ca2+-ATPase in the presence of alkaline phosphatase. The low substrate Km values and the hydrolysis which occurs at pH 7.4 mean that the enzyme could have a significant phosphohydrolytic role. However, liver cell phosphate concentrations, if accessible to the enzyme, are sufficient to strongly inhibit this activity.

Adenosine Triphosphate↗
PubMed1982

[Relationship between the genetic polymorphism of alkaline phosphatase and the resistance of broiler poultry to Marek's disease virus].

Studied was the polymorphism of alkaline phosphatase in blood plasma samples taken from 507 poulets and cocks of lines 66 and 77 of the Cornish breed, and lines 88 and 99 of the White Plymouth Rock breed. The birds were divided into three groups to test their resistance to Marek's disease: (1) controls, (2) infected with the virus of Marek's disease with 3 subgroups--resistant birds, slightly susceptible ones, and strongly susceptible ones, and (3) contacts, with two subgroups--survivals and birds that died. The blood plasma alkaline phosphatase was determined through horizontal electrophoresis on a starch gel, employing the method of Gahne. It was found that the alkaline phosphatase genetype FF frequency was lower with lines 66 and 77 than with line 88 and especially with line 99 of the White Plymouth Rock breed which proved most susceptible to the virus of Marek's disease. In the homozygotic alkaline phosphatase genetype SS none of the investigated lines showed any mortality. The resistance of broiler birds to Marek's disease was governed by the Akps allele, while the susceptibility was governed by the Akpf one. The former could be used as a genetic marker in the selection of initial lines of broiler birds by resistance, and the latter could be used as a marker in the selection by susceptibility.

Alkaline Phosphatase↗
PubMed1987

Serum alkaline phosphatase isoenzymes in hepatobiliary disorders resolved by use of immobilized pH gradients.

This new method for fractionating alkaline phosphatase isoforms in hepatobiliary disorders is based on isoelectric focusing on a mixed-type polyacrylamide support containing an immobilized pH gradient with a superimposed carrier-ampholyte gradient. The high-Mr alkaline phosphatase forms typical of hepatobiliary disease (greater than 1 mega-dalton), which cannot migrate into the Immobiline gel, are disaggregated in zwitterionic detergents (the most effective being sulfobetaine 3-12)--20 g/L in the sample, 5 g/L in the gel--suggesting that they are still complexed with membrane fragments or that they tend to aggregate spontaneously in solution. These isoforms focus in the pI 5-6 range (while alkaline phosphatases in normal serum focus in the pI 4-5 interval) in immobilized pH gradients, but behave as strongly acidic components by agarose isoelectric focusing in the presence of carrier ampholytes, suggesting that they are strongly complexed with the latter. On treatment with neuraminidase, the low-pI isoforms in normal serum focus in the pI 5-6 range typical of the hepatobiliary isoforms, suggesting that the latter are poorly glycosylated. By a second-dimension run, in a porosity gradient, followed by activity staining, all alkaline phosphatase forms that have entered the Immobiline gel in the first dimension (normal forms and high-Mr species) exhibit the same Mr (ca. 140,000 Da), suggesting that no new chains are synthesized in hepatobiliary disorders.

Alkaline Phosphatase↗
PubMed1977

New types of mutation affecting formation of alkaline phosphatase by Bacillus subtilis in sporulation conditions.

Mutations defining three new loci, sapA, sapB and phoS, were detected by their ability to overcome the phosphatase-negative phenotype of early-blocked asporogenous mutants in sporulation conditions. Synthesis of alkaline phosphatase by Bacillus subtilis is subject to 'vegetative' and 'sporulation' controls. The phoS mutations resulted in constitutive production of alkaline phosphatase and so could be altered in either the 'vegetative' or the 'sporulation' control system. The sapA and sapB mutations only affected alkaline phosphatase formation in sporulation conditions, and were considered to be sporulation specific. They rendered 'sporulation' alkaline phosphatase formation independent of all the spomutations tested, and so independent of the control of the dependent sequences of spo locus expression; as the enzyme was not formed constitutively, it remained subject to some other sporulation control. The sapA and phoS loci were placed between argC4 and metC3 on the genetic map; the sapB locus was located close to purB6. The three loci mapped separately from all known spo loci.

Alkaline Phosphatase↗