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PubMed1998

Relationship between alkaline phosphatase levels, osteopontin expression, and mineralization in differentiating MC3T3-E1 osteoblasts.

We are using viral oncogene probes to study the pathways by which osteoblast-specific gene expression is induced in ascorbic acid-treated MC3T3-E1 cells. The 12S product of the adenovirus E1A gene binds directly to key cellular regulators and, as a result, represses tissue specific gene expression and blocks differentiation in a wide variety of cell types. The main cellular targets of the E1A 12S product are the pRB family and p300/CBP family. The p300 family appears to be the primary target for E1A-mediated repression of tissue-specific gene expression in a variety of cell types. We have generated MC3T3-E1 cell lines that stably express either the wild-type 12S product or a mutant that targets p300/CBP, but not the pRB family. Using these constructs to dissect osteoblast differentiation, we found that targeting of p300/CBP appears to be sufficient to repress alkaline phosphatase expression, although a low but functional level of expression can be maintained if the pRB family is not targeted as well. Induction of alkaline phosphatase expression and activity can be dissociated from expression of late-stage markers such as osteocalcin and osteopontin. Surprisingly, cell lines exhibiting severe repression of alkaline phosphatase activity differentiate to a mineral-secreting phenotype much like normal MC3T3-E1 cells. Osteopontin induction is dependent on at least a minimal level of alkaline phosphatase activity, although it is not dependent on induction of alkaline phosphatase at the RNA level. If alkaline phosphatase is supplied exogenously, osteopontin expression can be induced in conditions in which endogenous alkaline phosphatase is severely repressed.

3T3 Cells↗

PubMed2006

Alkaline phosphatase activity in gingival crevicular fluid during canine retraction.

OBJECTIVES: The aim of the study was to investigate alkaline phosphatase activity in the gingival crevicular fluid (GCF) during orthodontic tooth movement in humans. SETTING AND SAMPLE POPULATION: Postgraduate orthodontic clinic. Ten female patients requiring all first premolar extractions were selected and treated with standard edgewise mechanotherapy. EXPERIMENTAL VARIABLE: Canine retraction was done using 100 g sentalloy springs. Maxillary canine on one side acted as experimental site while the contralateral canine acted as control. OUTCOME MEASURE: Gingival crevicular fluid was collected from mesial and distal of canines before initiation of canine retraction (baseline), immediately after initiation of retraction, and on 1st, 7th, 14th and 21st day and the alkaline phosphatase activity was estimated. RESULTS: The results show significant (p < 0.05) changes in alkaline phosphatase activity on the 7th, 14th and 21st day on both mesial and distal aspects of the compared experimental and control sides. The peak in enzyme activity occurred on the 14th day of initiation of retraction followed by a significant fall in activity especially on the mesial aspect. CONCLUSIONS: The study showed that alkaline phosphatase activity could be successfully estimated in the GCF using calorimetric estimation assay kits. The enzyme activity showed variation according to the amount of tooth movement.

Adolescent↗

PubMed1988

Alkaline phosphatase is a marker for myoid cells in cultures of rat peritubular and tubular tissue.

We have studied the distribution of histochemically detectable alkaline phosphatase in cultures of seminiferous tubule fragments and of peritubular cells from prepubertal rats. The same material also was immunohistochemically evaluated for the presence of desmin-containing intermediate filaments. The comparative analysis of alkaline phosphatase and desmin positivity shows that alkaline phosphatase histochemistry selectively detects desmin-containing contractile cells in tubular and peritubular cell cultures. We propose alkaline phosphatase as a novel marker for myoid cells that can be of help in screening, defining, and eventually standardizing the exact composition of peritubular cell cultures, a model that is of increasing interest in the study of cellular interactions in the testis.

Alkaline Phosphatase↗

PubMed1984

'Superactivation' of alkaline phosphatase activity by cycloheximide in rat hepatoma cell cultures.

We have found that rat hepatoma cells (R-Y121B) retain alkaline phosphatase activity, and that this enzyme activity is increased by cycloheximide. Actinomycin D also increased the enzyme activity. This increase due to actinomycin D was partially inhibited by cycloheximide. The characteristics of alkaline phosphatase of the cells treated or untreated with cycloheximide or actinomycin D were similar to each other; they were heat labile and the enzyme reaction was strongly inhibited by L-homoarginine, but weakly by L-phenylalanine. The increase in alkaline phosphatase activity with cycloheximide has been termed a 'superactivation' of alkaline phosphatase.

Alkaline Phosphatase↗

PubMed1978

Further observations on the differential precipitation of alkaline phosphatase isoenzymes by ethanol.

The proportions of the total activities of different isoenzymes of human alkaline phosphatase precipitated from serum by ethanol (20% v/v) were: liver phosphatase, 37%; placental phosphatase, 23%; bone phosphatase, 8.0%, and small-intestinal phosphatase, 3.7%. Treatment of the isoenzymes with neuraminidase reduced the percentages of non-intestinal phosphatases precipitated by ethanol to below 10%. Precipitation of intestinal alkaline phosphatase was unaffected by this treatment. The degree of solubility in ethanol therefore appears to be largely determined by the content of terminal sialic acid residues in the alkaline phosphatase molecules. In contrast the stabilities of the isoenzymes to heating at 56 degrees C were not significantly altered by neuraminidase digestion.

Alkaline Phosphatase↗

PubMed1987

Disposition of preformed mineral in matrix vesicles. Internal localization and association with alkaline phosphatase.

Studies were made on the disposition of mineral ions in matrix vesicles (MV) and their relationship to alkaline phosphatase by treatment of MV-enriched microsomes (MVEM) with graded levels of Ca2+-chelating agents to complex accessible ions, fractionation of MVEM on hypertonic sucrose gradients at two different pH values (7.5 and 8.0) to evaluate for the presence of calcium phosphate mineral, and passage of MVEM through cation-exchange columns to determine the accessibility of the Ca2+. The effect of removal of Ca2+ and Pi on subsequent ability of MVEM to induce mineral formation from synthetic cartilage lymph was also determined. Passage through cation-exchange columns revealed that MV Ca2+ was not freely exchangeable, but coeluted in the void volume with alkaline phosphatase. However, upon incubation in synthetic cartilage lymph, progressively more Ca2+ was retained by the column. These findings indicate that, initially, the majority of Ca2+ in MVEM is internal and not readily exchangeable, but as Ca2+ accumulates, progressively more becomes external. The mineral in MV is labile and readily susceptible to loss; treatment with graded levels of EGTA removed major portions of the original Ca2+ and Pi. 45Ca uptake by these mineral-depleted MV was markedly reduced, even in the presence of alkaline phosphatase substrates. Sucrose gradient fractionation of MVEM caused extensive loss of Pi, but not Ca2+, from the low-density alkaline phosphatase-rich fractions. This reveals that Ca2+ and Pi are not initially coupled together: Pi is largely soluble, whereas Ca2+ must be tightly bound. In the high-density vesicles, large amounts of both Ca2+ and Pi are present. The slightly enhanced recovery at higher pH suggests the presence of a solid mineral phase. During mineralization by MV, Ca2+ became externalized, and concomitantly alkaline phosphatase activity declined. This suggests that a direct association exists between the enzyme and the developing mineral.

Alkaline Phosphatase↗

PubMed1985

Acid and alkaline phosphatase activities in homogenates and subcellular fractions of human brain tumors.

This study is a quantitative analysis of acid and alkaline phosphatase activity in human brain tumor homogenates and subcellular fractions, in parallel with normal brain tissue. Glioblastoma multiforme, meningioma, astrocytoma and normal tissue samples were separated by ultracentrifugation into five subcellular fractions: nuclei (N), mitochondria (M), microsomes (P), ribosomes (R) and supernatant (S). These two phosphatases showed significant increase in astrocytoma and meningioma tissue homogenates, compared with normal brain tissue. Alkaline phosphatase levels were determined to increase significantly in glioblastoma multiforme tissue homogenates as compared with normals, while those of acid phosphatase were observed to decrease. The results of this investigation also indicate that the subcellular distributions of acid and alkaline phosphatase show differences in the different tumor types. This observation is evidence against metabolic uniformity in tumoral tissue.

Acid Phosphatase↗

PubMed1990

Relation of salivary phosphorus and alkaline phosphatase to the incidence of dental caries in children.

The phosphorus concentration and alkaline phosphatase activity in saliva may be related to the susceptibility to dental caries and supragingival calculus. Hence, the unstimulated mixed saliva of child patients were assayed by biochemical methods to determine the phosphorus concentration and alkaline phosphatase activity in such salivary samples. It is very interesting to note that higher phosphorus concentration and alkaline phosphatase activity were found in patients with rampant caries as compared to that with non rampant/control group.

Adolescent↗

PubMed1986

Action of zinc on bone metabolism in rats. Increases in alkaline phosphatase activity and DNA content.

The effects of zinc on the enzymes of femoral tissue were investigated in weanling rats that had been given zinc sulfate (1.0 mg Zn2+/100 g body wt) p.o. for 3 days. Administration of zinc caused a marked elevation of alkaline phosphatase and acid phosphatase activities, whereas it did not cause significant changes in succinate dehydrogenase, 5'-nucleotidase, ATPase, pyrophosphatase and beta-N-acetylglucosaminidase activities. The effect of zinc was greater on alkaline phosphatase of the femoral diaphysis. Zinc content of the femoral diaphysis was raised significantly by administration of zinc. The addition of zinc in concentrations of 10(-2)-10(2) microM did not produce a significant increase in alkaline phosphatase activity in the femoral diaphysis, indicating that zinc could not activate the enzyme. Administration of cycloheximide or actinomycin D completely inhibited the increase in alkaline phosphatase activity produced by administration of zinc. DNA content of the femoral diaphysis, but not epiphysis, was increased markedly by administration of zinc. The increases in both alkaline phosphatase activity and DNA content of the femoral diaphysis were not caused by administration of copper, manganese, cobalt, nickel and chromium(III). The present investigation suggests that zinc may induce the increase in alkaline phosphatase related to DNA synthesis and, as a result, stimulate bone growth.

Alkaline Phosphatase↗

PubMed2000

Comparison of serum catalytic activity and immunoreactivity of bone alkaline phosphatase in hypophosphatasia.

Hypophosphatasia is a rare bone disorder characterised by low levels of tissue non-specific alkaline phosphatase (TNSALP). Although TNSALP is widespread in virtually all tissues the clinical effects, when produced, seem only to affect the mineralizing tissue such as teeth and skeleton. The skeleton is severely affected in the perinatal form of the disease, when death may occur in utero, or may not be affected in the adult type variety of the disease. We therefore compared the catalytic (cBALP) and immunoreactivity (iBALP) of bone alkaline phosphatase isoenzyme in six families with hypophosphatasia. iBALP was measured using an IRMA method. cBALP was measured after electrophoretic separation of serum alkaline phosphatase isoenzymes on lectin containing agarose gel. The percentage of different isoenzymes was calculated using densitometric scanning and cBALP calculated from the known total serum alkaline phosphatase activity. Results showed cBALP=0.796+3. 269iBALP, r=0.9 p<0.01, in cases of hypophosphatasia. In general, the lower the iBALP and cBALP the more severe the skeletal disease. The bone isoenzyme level predicts the clinical severity of bone disease.

Adult↗

PubMed2006

Identification of non-specific alkaline phosphatases in hyphal cells of the fungus Neurospora crassa by in situ histochemistry.

The present study was designed to identify alkaline phosphatases in non-permeabilized hyphal cells of the fungus Neurospora crassa by staining these enzymatic activities with a modified azo dye coupling method. Our strategy allowed the identification of three non-specific alkaline phosphatase activities, one of them possibly being a novel putative enzyme, which is not responsive to either Mg(2+) or EDTA. Another alkaline phosphatase activity, whose location in the hyphal cell is regulated by phosphate, is stimulated by Mg(2+), inhibited by EDTA, and somehow dependent on the expression of the pho-2(+) -encoded Pi-repressible alkaline phosphatase.

Alkaline Phosphatase↗

PubMed1980

Studies on organ-specific alkaline phosphatases in relation to their diagnostic value.

The role of pH on tissue alkaline phosphatases have been investigated in different human tissues. Different isoenzymes have been observed in different organs. Bone and liver were similar in having the isoenzymes optimally active at 9.4 and pH 9.9. The kidney has a single alkaline phosphatase optimally active at pH 9.2, while the adrenal gland has two isoenzymes of optimum pH 9.2 and 10.1. Intestinal alkaline phosphatase was optimally active at pH 9.7.

Adrenal Glands↗

PubMed1981

High-molecular-mass alkaline phosphatase in serum and bile: nature and relationship with lipoprotein-X.

Using immunoelectrophoresis and other techniques, we have demonstrated an association between lipoprotein-X and (a) alkaline phosphatase and (b) other enzymes originating from the hepatocyte membrane, namely gamma-glutamyltransferase and leucine aminopeptidase. The high-molecular-mass forms of these enzymes, in both serum and bile, were precipitated by lipoprotein-X antiserum but not by antisera to other plasma proteins. The activity of high-molecular-mass alkaline phosphatase in serum was positively correlated with lipoprotein-X and with lipoprotein-X-associated alkaline phosphatase, both assessed semi-quantitatively. On the other hand, many sera possessed high activities of high-molecular-mass alkaline phosphatase but no detectable lipoprotein-X. Incubation of serum with conjugated bile salts and with synthetic detergents, at concentrations which did not dissociate the high-molecular-mass enzymes, caused parallel alterations in the electrophoretic mobility of serum lipoprotein-X and its associated enzyme activity. Incubation of normal dialyzed hepatic bile with normal, lipoprotein-X-negative serum produced an alteration in electrophoretic mobility of biliary lipoprotein and its associated enzyme activity from anodal to cathodal in agar gel. Digestion with papain had a variable effect on the different enzymes in the complex, without affecting the lipoprotein moiety. Leucine aminopeptidase was removed most readily from the complex to give the low-molecular-mass form present in normal serum; gamma-glutamyltransferase dissociated somewhat less readily, and alkaline phosphatase was completely resistant to dissociation from the complex. These results are discussed in the light of current knowledge, and a hypothesis is proposed for the nature of the high-molecular-mass enzymes in serum and bile.

Alkaline Phosphatase↗

PubMed1977

[Effect of polyenic antibiotics on the activity of alkaline phosphatase from Candida albicans].

Polyenic antibiotics (levorin, amphotericin B, nistatin) inhibit in vivo and in vitro the activity of membrane alkaline phosphatase from sensitive Candida albicans strain, and their inhibitory effect is twice lower on the enzyme from the resistant strain. A correlation is observed between the antibiotic concentration and the inhibitory effect on alkaline phosphatase activity. Nistatin is found to be the least efficient inhibitor (among the antibiotics studied) of alkaline phosphatase. The treatment of membranes with polyenic antibiotics does not result in solubilization of membrane proteins nad alkaline phosphatase. The data obtained are considered with respect to the effect of polyenic antibiotics on cell membrane structure.

Alkaline Phosphatase↗

PubMed1971

Effects of zinc and other metal ions on the stability and activity of Escherichia coli alkaline phosphatase.

Measurement of the ultraviolet circular dichroism of apo-(alkaline phosphatase) in urea solutions showed substantial denaturation in 3m-urea. A zinc-deficient mutant alkaline phosphatase behaved similarly. The stability of the enzyme in 6m-urea was followed as a function of its zinc content and was found to be dependent on the first two of the four zinc atoms bound by apoenzyme. Phosphatase activity was mostly dependent on a second pair of zinc atoms. Mn(2+), Co(2+), Cu(2+) or Cd(2+) also restored structural stability. Sedimentation-velocity and -equilibrium experiments revealed that dissociation of the dimer accompanied apoenzyme denaturation in urea concentrations of 1m or higher, without treatment with disulphide-reducing agent.

Alkaline Phosphatase↗

PubMed1985

Sensitivity of various visualization methods for peroxidase and alkaline phosphatase activity in immunoenzyme histochemistry.

Various chromogen protocols for visualizing peroxidase and alkaline phosphatase activity in immunoenzyme histochemistry were compared with respect to their sensitivity. They were tested on tissue sections of human skeletal muscle and in an antigen spot test using antibodies against slow skeletal muscle myosin. The chromogens included 3-amino-9-ethylcarbazole (AEC), 3, 3'-diaminobenzidine (DAB), p-phenylenediamine-pyrocatechol (PPD-PC) and 4-chloro-1-naphthol (CN) in peroxidase histochemistry, and 5-bromo-4-chloro-3-indolyl phosphate-nitro blue tetrazolium salt (BCIP-NBT), BCIP-tetra nitro blue tetrazolium salt (TNBT) and various combinations of substituted naphthol phosphate-diazonium salt in alkaline phosphatase histochemistry. DAB, CN, and PPD-PC were also employed with imidazole and DAB in addition to Co2+ and Ni2+ ions. The results indicate that DAB-imidazole and DAB-Co2+ and Ni2+ ions are the most sensitive chromogen protocols for visualizing peroxidase activity. Although no large differences were found between the various chromogen protocols for visualizing alkaline phosphatase activity, the protocol BCIP-TNBT is especially recommended. Furthermore, the various chromogen protocols were evaluated as to stability of chromogen solutions and final precipitates, background staining, localization properties, and enhancement of enzyme activity.

Alkaline Phosphatase↗

PubMed1994

Prostaglandin E2/parathyroid hormone-induced suppression of alkaline phosphatase activity is mediated by protein kinase C.

1. Bone resorptive factors, prostaglandin E2 and parathyroid hormone are shown to suppress alkaline phosphatase activity in a rat osteoblastic cell line. 2. Phorbol myristate acetate, but not dibutyryl cAMP or calcium ionophore can suppress alkaline phosphatase activity. 3. The protein kinase C inhibitors (H89, staurosporine) are able to block the suppression of alkaline phosphatase activity induced by prostaglandin E2 and parathyroid hormone. 4. These data suggest that protein kinase C is involved in the inhibition of alkaline phosphatase activity induced by prostaglandin E2 and parathyroid hormone.

Alkaline Phosphatase↗

PubMed1987

Serum osteocalcin, bone alkaline phosphatase isoenzyme and plasma tartrate resistant acid phosphatase in patients on chronic maintenance hemodialysis.

Biochemical indices of bone formation (serum osteocalcin and bone alkaline phosphatase isoenzyme) and osteoclastic function (plasma tartrate resistant acid phosphatase) were measured in 43 patients undergoing chronic hemodialysis and in 27 patients with primary hyperparathyroidism. The mean values for bone alkaline phosphatase isoenzyme and plasma tartrate resistant acid phosphatase but not for osteocalcin were significantly higher in primary hyperparathyroidism as compared with dialyzed patients. A significant positive correlation was found between the biochemical indices of osteoblasts and osteoclasts both in primary hyperparathyroidism and in dialyzed patients, indicating biological coupling between bone resorption and formation under these conditions. The regressions of osteocalcin vs bone alkaline phosphatase isoenzyme and/or plasma tartrate resistant acid phosphatase in dialyzed patients paralleled those in primary hyperparathyroidism but their distance differed significantly. It is concluded that in patients with renal failure, an increase in circulating osteocalcin by a relatively constant portion reflects decreased renal clearance. Any additional increase in osteocalcin serum level indicates an increased skeletal production of osteocalcin. The clinical value of bone alkaline phosphatase isoenzyme and plasma tartrate resistant acid phosphatase appears to be comparable with that of serum osteocalcin in primary hyperparathyroidism, and more exact than osteocalcin in renal failure.

Acid Phosphatase↗