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PubMed1975

[The isoenzyme pattern of serum alkaline phosphatase in patients on intermittent haemodialysis and kidney transplant recipients (author's transl)].

The total activity and the isoenzyme fractions of alkaline phosphatase were determined in the serum of 15 patients on intermittent haemodialysis and 32 kidney transplant recipients. The isoenzymes of alkaline phosphatase were separated by polyacrylamide gel disc electrophoresis. It was apparent that the increased activity of serum alkaline phosphatase in these patients was not limited to a distinct isoenzyme fraction. 5 of the 15 dialysis patients and 19 (59%) of the 32 kidney transplant patients showed a bone-type isoenzyme pattern. The possible causes for the presence of a bone-type alkaline phosphatase pattern are discussed. The fractionation of alkaline phosphatase gives a valuable indication as to the organ of origin of the particular fraction and is also of diagnostic value when the total activity of alkaline phosphatase lies within the normal range.

Alkaline Phosphatase↗
PubMed1986

Translation of rat intestinal RNA yields two alkaline phosphatases.

After translation of total rat intestinal RNA, immunoprecipitation using monospecific antiserum against rat intestinal alkaline phosphatase yielded two polypeptides in the adult duodenum and jejunum (molecular masses 62 and 65 kDa). Immunoprecipitation of both bands was blocked by a single purified alkaline phosphatase. In the adult ileum and in the entire small intestine of suckling pups, only the 62 kDa translation product was found. After fat feeding, translated alkaline phosphatase increased by an amount proportionate to the increase in enzyme activity previously seen in the serum. A small fraction of nascent alkaline phosphatase was translocated into microsomal vesicles, producing peptides of 65 and 69 kDa. Tunicamycin-treated membranes demonstrated a different signal peptide for each translation product. N-Terminal sequencing of the translation products showed leucine residues at similar positions, but overlap with the mature protein sequence was not demonstrated. On the basis of these data, we propose the presence of two mRNAs encoding alkaline phosphatase in the rat intestine.

Alkaline Phosphatase↗
PubMed1982

Activity of epiphyseal cartilage membrane alkaline phosphatase and the effects of its inhibitors at physiological pH.

The kinetics of epiphyseal cartilage membrane-bound alkaline phosphatase activity was studied at physiological pH using p-nitrophenylphosphate and pyrophosphate (PPi) as substrates. The effect of three general types of alkaline phosphatase inhibitors was studied on both purified and membrane-bound forms of the enzyme: 1) uncompetitive inhibitors (L-tetramisole and theophylline), 2) competitive inhibitors (phosphate, arsenate, and vanadate), and 3) metal ions (Mg2+, Ca2+, and Zn2+). These studies were aimed at elucidating the physiological role of epiphyseal cartilage membrane alkaline phosphatase. Hydrolytic activity of enzyme at pH 7.5 toward both PPi and p-nitrophenylphosphate was only one-tenth and one-hundredth, respectively, of that observed at optimal pH. Arsenate (Ki - 1.0-2.7 microM) and vanadate (Ki = 0.7-1.3 microM) were powerful inhibitors of alkaline phosphatase; phosphate (Ki = 20-50 microM) was inhibitory at levels two orders of magnitude below the concentration in cartilage extracellular fluid. Neither Zn2+, Ca2+, or Mg2+ was inhibitory toward p-nitrophenylphosphate hydrolysis, whereas all three competitively inhibited PPi hydrolysis. The data suggest that formation of poorly hydrolyzable Ca.PPi, Mg2.PPi, and Zn2.PPi complexes was responsible. Inhibition of PPi hydrolysis by Ca2+ occurred at levels within the physiological range. The close similarity in inhibition of both the purified and membrane-bound forms of alkaline phosphatase at pH 7.5 indicates that interaction with the membrane does not significantly alter conformation at the active site. The data obtained suggest that under physiological conditions, cartilage membrane alkaline phosphatase would be essentially inactive as a phosphohydrolase due to its intrinsically weak activity at pH 7.5 and the strong inhibitory effect of physiological levels of phosphate and Ca2+.

Alkaline Phosphatase↗
PubMedDate not supplied

PstI restriction fragment length polymorphism of the human intestinal alkaline phosphatase gene.

Restriction fragment length polymorphisms have previously been found in the placental alkaline phosphatase (PLAP) and germ cell alkaline phosphatase (GCAP) genes, but not in the closely related intestinal alkaline phosphatase (IAP) locus. We here report on a PstI restriction fragment length polymorphism in IAP found in Finns and Swedes but not in Saamis. A probable T-->G mutation in position 175 of intron 11 would create a new cleavage site for PstI. The borderline frequency of the mutant allele (0.01) is in agreement with previous observations suggesting that IAP is considerably less polymorphic than PLAP and GCAP.

Alkaline Phosphatase↗
PubMedDate not supplied

[Changes in the activity of alkaline phosphatase and the level of thiamine diphosphatase in simulations of B1 avitaminosis].

Alimentary B1 avitaminosis was attended by a declining activity of alkaline phosphatase in the brain and spleen of rats. A single administration of oxythiamine to rats in a dose of 400 mg/kg produced during the first hours an increased activity of alkaline phosphatase in the liver, brain and, to a lesser extent, in a number of other organs and reduced the thiamine-diphosphate content in the liver, brain and other tissues. The thiamin-diphosphate level in the brain returned back to normal in 12 hours, and in other tissues-towards the 3--5th day. In 24 hours after introduction of oxythiamine the activity of alkaline phosphatase was up in the liver alone, while in the brain the activity of the enzyme decreased. Thiamine, used in a dose of 400 mg/kg, exerted on the activity of alkaline phosphatase in a number of tissues an action similar to that of oxythiamine. It is suggested that the activation of alkaline phosphatase 3--12 hours following adminstration of a large dose of thiamine or oxythiamine is of a non-specific nature. Subcutaneous introduction of a commercial alkaline phosphatase preparation to rats brought down the thiamine-diphosphate level in all of the tissues under investigation. The presumed mechanisms accounting for the fall of thiamine-diphosphate and the possible part played in this process by alkaline phosphatase are discussed.

4-Nitrophenylphosphatase↗
PubMed1986

A highly sensitive assay method for human placental alkaline phosphatase involving a monoclonal antibody bound to a paper disk.

A monoclonal antibody which is specific for human placental alkaline phosphatase and does not cross-react at all with intestinal alkaline phosphatase was prepared, and a procedure for the determination of placental alkaline phosphatase activity in serum was developed involving this monoclonal antibody bound to a paper disk. The minimum amount of placental alkaline phosphatase detectable by this method is 0.0025 King-Armstrong unit. Good correlation with the heat-treatment method was obtained. Therefore this proposed method can be used as a routine clinical test for the determination of serum placental alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1984

5-Bromo-2'-deoxyuridine induces placental alkaline phosphatase biosynthesis in cultured choriocarcinoma cells.

5-Bromo-2'-deoxyuridine (BrdUrd) stimulated the biosynthesis and hence increased the activity of placental alkaline phosphatase in choriocarcinoma cells. While BrdUrd had no effect on the rate of degradation or processing of placental alkaline phosphatase, it increased the rate of phosphatase synthesis. The stimulation of enzyme activity could be completely accounted for by the increase in alkaline phosphatase protein. Both control and BrdUrd-induced cells contained polypeptides of 61,500 and 64,500 Da, identified as the precursor and fully processed forms of placental alkaline phosphatase monomer. The half-life of this enzyme monomer in both control and BrdUrd-treated cells was estimated to be 36 h. BrdUrd induced a specific increase in the placental alkaline phosphatase mRNA leading to the observed enhancement of biosynthesis. The continued rise in alkaline phosphatase biosynthesis in BrdUrd-induced cells following BrdUrd removal indicated that this analog acted by incorporation into DNA.

Alkaline Phosphatase↗
PubMed1975

Incidence and some properties of an electrophoretically slow form of alkaline phosphatase in sera of patients with diseases of the intestine.

A zone of alkaline phosphatase activity migrating at about 40 percent of the rate of liver phosphatase in gel electrophoresis has been detected in sera from 2 out of 22 cases of ulcerative colitis and 1 out of 32 cases of Crohn's disease, but in no other specimen from 33 patients with other diseases of the digestive tract. This rare form of alkaline phosphatase was unlike small-intestinal alkaline phosphatase in several properties. Its appearance in association with diseases of the colon suggests that the rare isoenzyme may originate in that organ. However, the slowly migrating alkaline phosphatase was equally prominent in serum specimens taken before and after operation in one patient who underwent a pan-proctocolectomy for the alleviation of uncontrollable ulcerative colitis.

Alkaline Phosphatase↗
PubMed2003

Effect of carbon source on alkaline phosphatase production and excretion in Aspergillus caespitosus.

The effect of several carbon sources on the production of alkaline phosphatase by the thermotolerant Aspergillus caespitosus was analysed. The fungus released high levels of alkaline phosphatases into the medium after being cultured for long periods with xylan or industrial residues such as wheat raw and sugar cane bagasse in the culture media. In contrast, the alkaline phosphatase activities were found only intracellulary when the fungus was cultured in glucose-supplemented media. The pH of the medium likely affects the process of enzyme secretion according to the carbon source used. Addition of xylan or industrial residues in the culture medium stimulated the secretion of phosphatases. In contrast, media supplemented with glucose or disaccharides promoted retention of these enzymes into the cells. The subcellular location activities of alkaline phosphatases were studied using histochemical and immunochemical methods and showed that alkaline phosphatases were present in the mycelial walls and septa.

Alkaline Phosphatase↗
PubMed1983

1,25-Dihydroxyvitamin D3 increases bone alkaline phosphatase isoenzyme levels in human osteogenic sarcoma cells.

The specific activity of alkaline phosphatase was increased in two human osteogenic sarcoma cell lines, SAOS and TE85, after treatment with 1,25 dihydroxy-vitamin D3 (1,25(OH)2D3). Enzyme activity increased when the cells were incubated with concentrations of 1,25(OH)2D3 between 10(-9) and 10(-7) M and cell growth was not inhibited at these concentrations. The specific activity of alkaline phosphatase was 4- to 7-fold higher than that in the control cells after 5 to 7 days of continuous exposure to 1,25(OH)2D3. Immunochemical studies demonstrated that the enzyme from both control and 1,25(OH)2D3-treated cultures cross-reacted with antisera specific for the phosphatase isoenzyme produced by normal human bone, and did not cross-react with antisera specific for the placental alkaline phosphatase isoenzyme. The increased enzyme activity in cultures induced with 1,25(OH)2D3 correlated with an absolute increase in the number of bone-specific phosphatase molecules, as determined by radioimmunoassay. No effect on alkaline phosphatase activity was observed when the cells were treated with other vitamin D metabolites or with 5-bromo-2'-deoxyuridine. Comparative studies demonstrated that hydrocortisone, another steroid hormone, increased the phosphatase activity with a different time course than did 1,25(OH)2D3. High affinity cytoplasmic receptors for 1,25(OH)2D3 and hydrocortisone were found in the SAOS and TE85 cells.

Alkaline Phosphatase↗
PubMed1988

Effect of pyrimidine deoxynucleosides and sodium butyrate on expression of the glycoprotein hormone alpha-subunit and placental alkaline phosphatase in HeLa cells.

Production of the glycoprotein hormone common alpha-subunit and placental alkaline phosphatase activity can be modulated in HeLa cells by a variety of deoxynucleosides. Dose response curves for thymidine (Thd), fluorodeoxyuridine (FdUrd), bromodeoxyuridine (BrdUrd) and iododeoxyuridine (IdUrd) demonstrate that, in general, alkaline phosphatase was increased by lower concentrations of inducer than was alpha-subunit. The deoxynucleosides were not as effective as sodium butyrate as inducers of either protein. Whereas Thd and the halogenated dUrd derivatives enhanced protein expression, deoxycytidine (dCyd) had negative effects. Induction by deoxynucleosides of both alkaline phosphatase and alpha-subunit was inhibited by dCyd, but induction of alkaline phosphatase by butyrate was more sensitive to dCyd inhibition than was the butyrate-mediated induction of alpha-subunit. These results suggest that the two proteins are not regulated in a coordinate manner. Reversal of alkaline phosphatase induction by dCyd was not observed in cells preincubated with sodium butyrate for 6-24 h before the addition of dCyd, indicating that the deoxynucleoside interferes with an early event in the butyrate-mediated response. Combinations of butyrate with Thd, BrdUrd or IdUrd were synergistic with respect to the induction of HeLa-alpha. It is concluded that incorporation of the deoxynucleosides into DNA may not be required for the synergistic response since 2',5'-dideoxythymidine was an effective as Thd. Cytoplasmic dot hybridizations demonstrate that a primary effect of the various effectors is to increase the steady-state levels of alpha-subunit mRNA. There was a good correlation between alpha-subunit accumulation and corresponding levels of alpha-mRNA, suggesting that regulation occurs at a pretranslational site. Although the mechanism(s) is not understood, these data provide evidence that nucleosides or their derivatives can significantly affect gene expression.

Alkaline Phosphatase↗
PubMed1989

Subcellular and ultrastructural localization of alkaline phosphatase in lactating rat mammary glands.

The subcellular fractions of lactating rat mammary glands were isolated by differential centrifugation. The mean specific activity of alkaline phosphatase in various fractions was in order greatest to least: microsomes, Golgi, mitochondria, nuclei, and cytosol. Alkaline phosphatase was examined cytochemically by transmission electron microscopy. Alkaline phosphatase activity was localized on myoepithelial membranes, basal and possibly lateral membranes of secretory epithelial cells, and endothelial cells. This finding agreed with biochemical data associating this enzyme activity with microsomes. However, intracellular activities could not be detected on Golgi, secretory vesicles, or apical plasma membranes. Saponin uncovered the activity in that portion of the endoplasmic reticulum of secretory cells adjacent to myoepithelial cells. The identify of this enzyme was further confirmed by selective inhibition studies using dithiothreitol and levamisole. Alkaline phosphatase activities were detected biochemically in lipid droplet "membranes" of secretory epithelium and fat globule membranes. Activity decreased with increasing globule size, indicating that milk alkaline phosphatase originates from lipid droplets of secretory epithelium. The predominance of alkaline phosphatase activity in myoepithelial cell plasma membranes suggests that this enzyme could be involved in cell surface reactions related to oxytocin-mediated milk ejection. In secretory epithelium, it was associated with basal and possibly lateral membranes and lipid droplets that lead to the secretion of milk fat.

Alkaline Phosphatase↗
PubMed1991

Properties of amphiphilic and hydrophilic forms of alkaline phosphatase from human liver.

Amphiphilic and hydrophilic forms of alkaline phosphatase differed in electrophoretic mobility, sensitivity to heat, activation by phospholipids and albumin, and affinity of monoclonal antibodies, but were similar in substrate Km and inhibitor Ki values, sensitivity to sodium dodecyl sulfate, and electrophoretic behavior on desialylation. Chemical cross-linking experiments failed to conclusively demonstrate an aggregated state of amphiphilic alkaline phosphatase in Triton X-100. Further, attempts to identify a polymeric hybrid between amphiphilic forms of human liver and placental alkaline phosphatase were unsuccessful. We conclude that the covalent attachment of the hydrophobic phosphatidyl-inositol membrane anchor causes the amphiphilic form to behave anomalously on electrophoresis and to affect certain of the enzyme's catalytic and physical properties.

Alkaline Phosphatase↗
PubMed1992

Decreased abundance of alkaline phosphatase and calbindin-D9K mRNAs in the intestine of the spontaneously hypertensive rat.

Alkaline phosphatase activity and calbindin-D9K immunoreactivity are decreased in the intestines of spontaneously hypertensive rats (SHRs). To investigate the potential role of altered gene expression in these decreases, we measured, by Northern blot analyses, the abundances of alkaline phosphatase and calbindin-D9K mRNAs in the proximal regions of the small intestines of 14-week-old SHR and control Wistar-Kyoto (WKY) rats. Alternate 4-cm segments of intestine were used for measurements of the proteins (0-4 cm, 8-12 cm, and 16-20 cm from pylorus, segments A1, B1, and C1, respectively) and mRNAs (4-8 cm, 12-16 cm, and 20-24 cm, segments A2, B2, and C2). Calbindin-D9K (immunoassay) was decreased in SHR vs WKY rats by 27%, 64%, and 67% in segments A1, B1, and C1, respectively (P < 0.01); its mRNA was decreased to a similar extent (69%, 82%, and 80%, respectively; P < 0.002 by analysis of variance). Alkaline phosphatase activity was decreased in SHRs by 58%, 54%, and 51% in segments A1, B1, and C1, respectively (P < 0.01); the abundance of its 3.0-kb mRNA was decreased to a similar extent: 57%, 80%, and 69% in segments A2, B2, and C2, respectively (P < 0.02). The mean decreases of the 2.7-kb mRNA of alkaline phosphatase were statistically significant (P < 0.02) but smaller (38%, 40%, and 35%). The mean abundance of vitamin D receptor mRNA in the same animals was decreased slightly in SHR vs WKY rats (3%, 36%, and 20% in segments A2, B2, and C2, respectively), but the difference in the values was not statistically significant. Decreases in alkaline phosphatase activity and calbindin-D9K immunoreactivity may reflect decreased mRNA abundance and not decreased enzyme-specific activity or increased protein degradation.

Alkaline Phosphatase↗
PubMed1976

Alkaline phosphatase in HeLa cells. Stimulation by phospholipase A2 and lysophosphatidylcholine.

Treatment of homogenates and plasma membrane preparations from HeLa cells with phospholipase A2 (EC 3.1.1.4) caused a 50% increase in activity of membrane-associated alkaline phosphatase. Lysophosphatidylcholine, dispersed in 0.15 M KCl, affected alkaline phosphatase in a similar fashion by releasing the enzyme from particulate fractions into the incubation medium and by elevating its specific activity. Higher concentrations of lysophosphatidylcholine solubilized additional protein from particulate fractions but did not further increase the specific activity of the released alkaline phosphatase. Particulate fractions from HeLa cells were exposed to the effects of liposomes prepared from lysophosphatidylcholine and cholesterol. The ratio of particulate protein/lysophosphatidylcholine (by weight) required for optimal activation of alkaline phosphatase was one. Kinetic studies indicated that phospholipase A2 and lysophosphatidylcholine enhanced the apparent V of the enzyme but did not significantly alter its apparent Km. The increased release of alkaline phosphatase from the particulate matrix by lysophosphatidylcholine was confirmed by disc electrophoresis. The release of the enzyme by either phospholipase A2 or by lysophosphatidylcholine appeared to be followed by the formation of micelles that contained lysophosphatidylcholine. The new complexes had relatively less cholesterol and more lysophosphatidylcholine than the native membranes. The possibility that lysophosphatidylcholine formed a lipoprotein complex with the solubilized alkaline phosphatase was indicated by a break point in the Arrhenius plot which was evident only in the lysophosphatidylcholine-solubilized enzyme but could not be demonstrated in alkaline phosphatase that had been released with 0.15 M KCl alone.

Alkaline Phosphatase↗
PubMed1995

Tubulin polymerization by paclitaxel (taxol) phosphate prodrugs after metabolic activation with alkaline phosphatase.

Paclitaxel (taxol) phosphate derivatives BMY46366, BMY-46489, BMS180661 and BMS180820 were used to determine the ability of alkaline phosphatase to convert these water-soluble potential prodrugs to tubulin-polymerizing metabolites (i.e., paclitaxel). Compounds were treated up to 180 min with an in vitro metabolic activation system composed of 10% bovine alkaline phosphatase in 0.2 M tris, pH 7.4, or in 0.2 M glycine, pH 8.8, plus 0.05 M MgCl2. Samples were tested (either by direct addition or after methylene chloride extraction/dimethyl-sulfoxide resuspension) in spectrophotometric tubulin polymerization assays utilizing bovine-derived microtubule protein. Pretreatment of 2'- and 7-phosphonoxyphenylpropionate prodrugs BMS180661 and BMS180820 with alkaline phosphatase for 30 to 120 min yielded relative initial slopes of about 20 to 100% at test concentrations equimolar to paclitaxel. High-performance liquid chromatography/mass spectrometry of BMS180661 treated with alkaline phosphatase confirmed the production of paclitaxel from the prodrug. In contrast, 2'- and 7-phosphate analogs BMY46366 and BMY46489 treated with alkaline phosphatase were not active in tubulin assays. None of the paclitaxel phosphate prodrugs polymerized tubulin in the absence of metabolic activation. The differences in tubulin polymerization with metabolic activation may be related both to accessibility of the phosphate group to the enzyme and to anionic charge effects. These results demonstrate that certain paclitaxel phosphate prodrugs can be metabolized by alkaline phosphatase to yield effective tubulin polymerization.

Alkaline Phosphatase↗
PubMed1988

Immunodiagnosis of meningeal leukemia using the alkaline phosphatase procedure.

To optimalize the diagnosis of meningeal involvement in ALL we adapted the alkaline-phosphatase-anti-alkaline-phosphatase procedure (APAAP) to be used for cerebrospinal fluid (CSF) examination. The study was performed on 19 patients (9 children with leukemia) with CSF hypercellularity. 490 determinations with a panel of 12 monoclonal antibodies were performed. This method was convenient, cell morphology was preserved so that combined morphological and immunological characterization of specific cells was possible in mixed cell populations. The combined study of immunological and morphological criteria produced more accurate results than those based on morphological criteria alone. The APAAP technique is useful for small numbers of cells. The preservation of antigenic reactivity in frozen CSF smears may be of use in reevaluation studies.

Alkaline Phosphatase↗
PubMed1979

Prognostic significance of alkaline phosphatase measurements in patients with osteogenic sarcoma receiving chemotherapy.

During the period January 1975 to August 1977, alkaline phosphatase levels in 30 patients with osteogenic sarcoma were closely followed in an attempt to determine if these measurements had clinical value in predicting the course of patients with this disease. Of 17 patients with elevated preoperative alkaline phosphatase levels, 12 recurred. Of 13 patients with normal preoperative alkaline phosphatase levels, only 4 recurred (p less than .05). Thus, alkaline phosphatase levels that were elevated preoperatively were correlated with poor prognosis. A similar correlation between postoperative alkaline phosphatase levels and prognosis could not be made.

Adolescent↗