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PubMed1987

Developmental appearance of Gla proteins (osteocalcin) and alkaline phosphatase in tooth germs and bones of the rat.

The tissue distribution and developmental appearance of alkaline phosphatase and Gla proteins, relative to mineralization were examined. Undecalcified sections of tooth germs, calvaria and alveolar bone of the rat were immunostained for Gla proteins, (indirect immunofluorescence and avidin-biotin-peroxidase-complex) and then stained for alkaline phosphatase activity. In the growth regions of tooth germs, Gla protein was observed in young odontoblasts and in early predentin, at a stage prior to formation of the first mineralized dentin. Similar results were obtained for bone: young osteoblasts as well as osteoid were immunopositive for Gla protein prior to formation of the first mineralized bone. Histochemical staining revealed that differentiating odontoblasts and osteoblasts exhibited alkaline phosphatase activity at stages prior to appearance of Gla proteins and that cells adjacent to odontoblasts and osteoblasts (not directly involved in the formation of predentin/dentin and osteoid/bone) stained for alkaline phosphatase, but not for Gla proteins. We conclude, that in these bone- and dentin-forming cells, alkaline phosphatase activity is expressed before the appearance of Gla proteins, but that both appear before the onset of mineralization. We also conclude that Gla protein is a more specific marker for bone and dentin formation than histochemical alkaline phosphatase activity, since only the cells directly involved in these processes were immunostained for Gla protein.

Alkaline Phosphatase↗
PubMed1988

Insulin action on brain microvessels; effect on alkaline phosphatase.

The effects of insulin on brain alkaline phosphatase activity have been examined. Insulin inhibited the activity of alkaline phosphatase on brain microvessels in in vitro experiments. The inhibition observed was of the non-competitive type. These observations indicate that the hormone is able to induce neurochemical modifications revealed in this case as changes in the phosphate transfer enzymes in brain microvessels.

Alkaline Phosphatase↗
PubMed1977

Comparative study of alkaline phosphatase isoenzymes, bone histology, and skeletal radiography in dialysis bone disease.

Liver, intestinal, and bone alkaline phosphatase isoenzymes were measured using heat stability and L-phenylalanine inhibition techniques in 78 patients on intermittent haemodialysis. Fifty-five patients had abnormalities in one or more of the isoenzymes. Changes in bone and intestinal alkaline phosphatase activities seemed to be related and raised liver isoenzyme activity was associated with the development of liver disease. Abnormal histological and radiological findings were better correlated with bone alkaline phosphatase levels than with total alkaline phosphatase, and serial estimations of bone isoenzyme activity were useful in assessing the response of renal osteodystrophy to treatment with a vitamin D analogue. Serum alkaline phosphatase isoenzyme measurement provides another useful and non-invasive index for monitoring metabolic bone disease in patients with chronic renal failure.

Adult↗
PubMed1991

Detection of bone-type alkaline phosphatase by monoclonal antibodies reacting with human osteosarcoma-associated antigen.

The antigen detected by monoclonal antibodies reacting with human osteosarcoma-associated antigen was shown to be a phosphatidyl-inositol (PI)-glycan-anchored protein, which can be released from the cell surface by PI-specific phospholipase C-treatment. The antigen detected by 2D3 and 2H10 antibodies exhibited alkaline phosphatase activity. Both antibodies strongly reacted with bone-type alkaline phosphatase. However, importantly, immunohistochemical analysis demonstrated that 2D3 and 2H10 did not react with alkaline phosphatase present in kidney or liver. In addition, neither placental nor intestinal alkaline phosphatase was recognized by 2D3 and 2H10 antibodies. These results indicated that two monoclonal antibodies, 2D3 and 2H10, are highly specific for bone-type alkaline phosphatase and can distinguish bone alkaline phosphatase from liver alkaline phosphatase in spite of the fact that liver and bone alkaline phosphatase are encoded by the same gene.

Alkaline Phosphatase↗
PubMed1976

Serum alkaline phosphatase, nucleotide pyrophosphatase, 5'-nucleotide and lipoprotein-X in cholestasis.

The nature of the stationary band of alkaline phosphatase, which occurs on starch gel electrophoresis of sera from patients with biliary obstruction, has been examined. Stationary alkaline phosphatase was eluted from Sepharose 4-B gel close to the void volume and together with the plasma membrane enzymes, nucleotide pyrophosphatase and 5'-nucleotidase, and with lipoprotein-X. Electron microscopy of concentrates of stationary alkaline phosphatase, prepared by ultracentrifugation and gel filtration, showed large (0.3--1 mum diameter) and small structures (30-70 nm diameter) by negative staining. The activity of the stationary alkaline phosphatase was associated in fixed sections with particles of about 10 nm X 40 nm resembling those of lipoprotein-X. It is suggested that the stationary alkaline phosphatase does not move into starch gel during electrophoresis because it is particulate. In agar electrophoresis the alkaline phosphatase which was stationary on starch gel moved towards the cathode with lipoprotein-X.

Adult↗
PubMed1987

myo-inositol action on gerbil intestine: alterations in alkaline phosphatase activity upon phosphatidylinositol depletion and repletion in vivo.

The influence of phosphatidylinositol (PI) on intestinal alkaline phosphatase activity was studied in myo-inositol deficient gerbils. A reduction of membrane PI in intestinal mucosa to 30-40% of the control was produced by feeding female gerbils a myo-inositol-deficient diet containing coconut oil for 2 weeks. As expected, the animals developed typical intestinal lipodystrophy with abnormal fat accumulation. In the PI-depleted animal, intestinal alkaline phosphatase activity was reduced to 20-30% of the control group. The levels of both membranous and soluble enzymes in intestinal mucosa were affected, but there were no changes in liver, kidney and plasma levels. When the lipodystrophic gerbils were given dietary myo-inositol, the complete repletion of intestinal membrane PI to the control level occurred 36 h later, whereas membrane-bound alkaline phosphatase activity in intestine was not restored to the control level until 72 h later. Administration of cycloheximide or actinomycin D did not block this enzyme induction. Lymphatic output of triacylglycerol into the bloodstream was stimulated 10-fold at 18 h of myo-inositol repletion, but there was no parallel increase in the activity of alkaline phosphatase in plasma during this early phase of intestinal recovery. Thus, these data suggest a possible regulatory role of PI in the processing and/or turnover of alkaline phosphatase in vivo, but a negative role of alkaline phosphatase in lipid transport across gerbil intestine.

Alkaline Phosphatase↗
PubMed1991

Differential theophylline inhibition of alkaline phosphatase and 5'-nucleotidase of bovine milk fat globule membranes.

1. The effects of theophylline (1,3-dimethylxanthine) on alkaline phosphatase and 5'-nucleotidase activities of bovine milk fat globule membranes (MFGM) were examined. 2. Theophylline inhibited MFGM alkaline phosphatase in a concentration-dependent manner with 50% inhibition produced by 99 +/- 28 microM theophylline. 3. The 5'-nucleotidase activity was resistant to theophylline inhibition with 50% inhibition produced by 33.9 +/- 3.1 mM theophylline. 4. Theophylline was an uncompetitive inhibitor of MFGM alkaline phosphatase with a Ki of 126 +/- 15 microM. 5. The extent of theophylline inhibition of alkaline phosphatase activity was independent of the substrate utilized in the assay. 6. The effect of theophylline on bovine MFGM alkaline phosphatase was similar to theophylline effects on other mammalian alkaline phosphatases of liver/bone isoenzyme origin.

5'-Nucleotidase↗
PubMed1988

The autorelease of alkaline phosphatase from the plasma membrane during the incubation of cultured liver cell homogenates.

When a rat hepatoma cell (R-Y121B) homogenate was incubated at 37 degrees C, 30-70% of the total alkaline phosphatase was released into the supernatant fluid from the precipitate fractions. The release reached a plateau level after 10 h of incubation at 37 degrees C. The optimum pH value for the release was 7.4. Alkaline phosphatase activity increased during the incubation of the cell homogenates, but this increase was independent of the enzyme release. Serum increased not only alkaline phosphatase activity in the cultured cells but also enzyme release in their homogenates. In addition, we examined a rat liver homogenate and the following 11 cell lines: 3 hepatoma cell lines, including the R-Y121B cell line, 4 liver cell lines, 2 human urinary bladder carcinoma cell lines, a kidney cell line, and a mouse adrenal tumor cell line. Only in the cultured liver cell line and hepatoma cell lines, 30-60% of the total enzyme was released into the soluble fraction from the precipitate fractions; the release was not observed in the other cell lines, nor in the rat liver homogenate. The release of alkaline phosphatase took place in both heat-stable and heat-labile alkaline phosphatases. Alkaline phosphatase, extracted from cell homogenates, showed two bands during polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The mobilities of the two bands changed inversely with or without sodium dodecyl sulfate. In general, the alkaline phosphatase which showed slow mobility with sodium dodecyl sulfate was more readily released from the plasma membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1982

In vitro stimulation of alkaline phosphatase activity in immature embryonic chick pelvic cartilage by adenosine 3'5'-monophosphate.

Cyclic AMP content in embryonic chick pelvic cartilage increases significantly as the embryo ages from 8 to 10 d. This in ovo elevation in cyclic AMP content precedes maximal cartilage alkaline phosphatase activity by some 24 h. We studied whether this temporal relationship may be causally related, using an in vitro organ culture. Incubation of pelvic cartilage from 9- and 10-d embryos in medium containing monobutyryl cyclic AMP (BtcAMP) resulted in significant increases in alkaline phosphatase activity (220 and 66 percent, respectively) as compared to that of cartilages incubated in medium alone. This stimulation was both concentration- and time-dependent with maximal response at 0.5 mM BtcAMP and 4-h incubation, respectively. Similar incubations of cartilage in medium containing 1-methyl-3-isobutyl xanthine (MIX), 0.25 mM, also resulted in increased alkaline phosphatase activity (114 percent). However, pelvic cartilage from 11-d embryos incubated in medium containing BtcAMP or MIX showed no increase in alkaline phosphatase activity. We postulated that developmental age was the factor responsible for this difference in response and that immature cartilage (that with little or no alkaline phosphatase activity) would respond to BtcAMP whereas mature cartilage (that with significant alkaline phosphatase activity) would not. This was tested by incubating end sections of 11-d cartilage, which have little alkaline phosphatase activity, and center sections, which have significantly alkaline phosphatase activity, with both BtcAMP and MIX. Alkaline phosphatase activity in end sections (immature cartilage) was stimulated by BtcAMP and MIX, whereas it was not stimulated in the center sections. Actinomycin D and cycloheximide inhibited BtcAMP and MIX stimulation of alkaline phosphatase activity. Thus, the in vitro data suggest that cyclic AMP is a mediator for the stimulation of alkaline phosphatase activity in embryonic cartilage.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Low serum levels of alkaline phosphatase of bone origin: a good marker of adynamic bone disease in haemodialysis patients.

BACKGROUND: Adynamic bone disease was recently described to be increasingly prevalent in the dialysis population. At present the diagnosis of this type of renal osteodystrophy can only be made by bone histomorphometry. We assessed the value of different biochemical serum markers in the diagnosis of adynamic bone disease. METHODS: In 103 haemodialysis patients a bone biopsy was performed after double tetracycline labelling, and the serum levels of intact PTH, osteocalcin, and the bone isoenzyme of alkaline phosphatase were determined. Bone alkaline phosphatase was measured by an optimized agarose gel electrophoretic method, recently shown to have a high accuracy, precision and reproducibility, also in the lower range. RESULTS: In 38 (37%) of the patients the diagnosis of adynamic bone disease was histologically established. Constructing receiver operator curves optimal cut-off levels for the diagnosis of adynamic bone disease were determined, being <=27 U/litre for the bone isoenzyme of alkaline phosphatase, <=14 microg/litre for osteocalcin and <=150 pg/ml for intact PTH. Concentrations of bone alkaline phosphatase or intact PTH below these cut-off levels, were shown to be the best performing tests in the detection of adynamic bone disease as indicated by a sensitivity of 78.1 and 80.6% and a specificity of 86.4 and 76.2% respectively. Applying Bayes' theorema, it was calculated that in the current haemodialysis population in which a prevalence of adynamic bone disease up to 35% has been described, the positive predictive values for the proposed cut-off values are 75% for bone alkaline phosphatase, 65% for intact PTH and 55% for osteocalcin. Moreover, in this population, levels of bone alkaline phosphatase and intact PTH below the optimal cut-off excluded hyperparathyroid bone disease. CONCLUSION: In view of the relative easy and accurate methodology for bone alkaline phosphatase determination, the closer physiological link with osteoblast function and the lesser expense for its determination we suggest that this marker is a useful tool in the non-invasive diagnosis of the adynamic type of bone disease in the individual patient.

Alkaline Phosphatase↗
PubMed1985

Electrophoretic characterization of hepatic alkaline phosphatase released by phosphatidylinositol-specific phospholipase C. A comparison with liver membrane and serum-soluble forms.

Alkaline phosphatase was solubilized from plasma membrane of rat liver with butanol-ol, bile acids or sodium deoxycholate, and electrophoretically compared with a soluble form in serum which was derived from the liver. The three enzyme preparations from the plasma membrane migrated at the same position on polyacrylamide-gel electrophoresis in the presence of either Triton X-100 or sodium dodecyl sulphate. The mobility of them, however, was distinctly different from that of the serum-soluble form of the liver-derived alkaline phosphatase. On the other hand, phosphatidylinositol-specific phospholipase C isolated from Bacillus cereus was used to release alkaline phosphatase from plasma membrane. The released alkaline phosphatase was demonstrated to have the same mobility as the serum-soluble form on polyacrylamide-gel electrophoresis in the presence or absence of detergents. The phospholipase C also converted the butan-1-ol-extracted membrane form into the serum-soluble form. The results suggest that release of alkaline phosphatase from the liver into serum is not simply caused by a detergent effect of bile salts, but involves an enzymic hydrolysis of phosphatidylinositol, with which alkaline phosphatase may strongly interact in the membrane.

1-Butanol↗
PubMed1986

Intestinal calcium and phosphate transport and intestinal alkaline phosphatase.

The aim of the study was to investigate the link, if any, between alkaline phosphatase activity and intestinal calcium and phosphate transport using the hypophysectomized (HX) rat model. Ionic transport was evaluated by the in situ ligated loop technique. Hypophysectomy (HX) resulted in a decrease in both duodenal and jejunal alkaline phosphatase activity but did not alter the active transport of calcium and phosphate. Vitamin D depletion (-D), suppressed intestinal transport in the HX rat without altering alkaline phosphatase activity. Repletion of 1,25(OH)2D3 in the -DHX rat resulted in an increase in active transport of calcium and phosphate without altering the alkaline phosphatase activity. Thus, using the HX animal model, we were able to differentiate intestinal alkaline phosphatase activity from the overall intestinal transport of calcium and phosphate.

Alkaline Phosphatase↗
PubMed1990

A heat-stable alkaline phosphatase from Penaeus japonicus Bate (Crustacea: Decapoda): a phosphatidylinositol-glycan anchored membrane protein.

1. A heat-stable alkaline phosphatase was purified from Penaeus japonicus, with a final specific activity of 21,280 U/mg of protein. 2. In polyacrylamide-gel electrophoresis under non-denaturing conditions, the purified shrimp alkaline phosphatase was found to have an identical molecular size and surface charge as the human placental enzyme. 3. By using SDS-PAGE, the monomers of shrimp alkaline phosphatase were discovered to have a Mr 55,000 but those of human placental enzyme with a Mr 70,000. Deglycosylation decreases the Mr values of the subunits to 33,000 for shrimp alkaline phosphatase. 4. The purified alkaline phosphatase from shrimp was recovered with both the attachment sites for sialic acids and phosphatidylinositol. 5. The shrimp alkaline phosphatase has an isoelectric point (pI) of 7.6 and the human placental enzyme has a pI of 4.8.

Alkaline Phosphatase↗
PubMedDate not supplied

Symptomatic and scintigraphic improvement after intravenous pamidronate treatment of Paget's disease of bone in patients with normal serum alkaline phosphatase levels.

OBJECTIVE: To describe three patients with symptomatic Paget's disease of bone who presented with normal levels of serum alkaline phosphatase. METHODS: We present three cases of Paget's disease of bone and chronicle the laboratory, scintigraphic, and clinical findings relative to treatment with intravenously administered pamidronate. RESULTS: Although measurement of serum total alkaline phosphatase usually provides a general indication of bone turnover in Paget's disease, about 15% of patients present with normal serum alkaline phosphatase levels. Nonetheless, these patients may have active Paget's disease when assessed with bone scintigraphy or urinary markers of bone resorption. All three study patients had xray findings characteristic of Paget's disease of bone, increased uptake of radiotracer material on bone scans, and elevated levels of urinary markers of bone resorption but normal alkaline phosphatase levels. They were treated with intravenously administered pamidronate, 60 mg once weekly for 2 to 3 consecutive weeks. After treatment, the serum alkaline phosphatase level decreased by 19 to 36%, markers of bone resorption normalized, bone scans showed improvement, and bone pain resolved. CONCLUSION: Pagetic activity in bone and related clinical manifestations may be present in the setting of a normal serum alkaline phosphatase level. Appropriate therapy should not be withheld because of the normal alkaline phosphatase.

Aged↗
PubMed1995

Maternal serum placental alkaline phosphatase level and risk for preterm delivery.

OBJECTIVE: The purpose of this study was to determine whether elevated midtrimester serum placental alkaline phosphatase levels are predictive of preterm delivery. STUDY DESIGN: By use of banked serum specimens from a sample of women who had received maternal serum alpha-fetoprotein screening, placental alkaline phosphatase values for multiples of the median were obtained from 270 mothers who had experienced a preterm delivery and from 1598 mothers of term, appropriate-for-gestational-age infants. Specimens were analyzed for placental alkaline phosphatase by means of a monoclonal antibody enzyme-linked immunosorbent assay. Logistic regression was used to determine whether placental alkaline phosphatase was associated with preterm birth, while potential confounders were controlled for. RESULTS: Women with placental alkaline phosphatase levels > or = 2.0 multiples of the median were significantly more likely to be delivered of a preterm infant in the current pregnancy compared with women with levels < 2.0 multiples of the median (odds ratio 2.9, 95% confidence interval 2.1 to 3.9). The likelihood of preterm birth increased significantly with higher multiples of the median (p < 0.001). CONCLUSION: Women with elevated placental alkaline phosphatase levels are at increased risk for preterm delivery. Additional studies are needed to evaluate the clinical utility of placental alkaline phosphatase testing as a means of identifying mothers at risk for preterm birth.

Adolescent↗
PubMed1990

Purification and characterisation of the placental-like alkaline phosphatase from ovarian epithelial tumours.

The placental alkaline phosphatase was purified by immunoaffinity chromatography from ovarian epithelial tumours to homogeneity. Up to 40% of the catalytical phosphatase activity in these tumours was derived from this placental type alkaline phosphatase (PLAP). The purified enzyme were similar to those of PLAP, whereas the PLAP-like isozyme was more heat-stable and resistant to 8 M urea than PLAP. The amino terminal sequence of the PLAP-like enzyme demonstrated heterogeneity at position three in the N-terminal end compared with PLAP. Phenyl-Sepharose affinity chromatography and different lectin chromatographies demonstrated the tumour-derived enzyme to be microheterogeneous, both with regard to concanavalin A binding and hydrophobicity properties.

Alkaline Phosphatase↗
PubMed1980

Properties of alkaline phosphatase in crude homogenates of human diploid fibroblasts.

The kinetic properties of the "constitutive" and the "induced" alkaline phosphatase in diploid fibroblasts are compared with those of the enzymes in crude tissue homogenates. Both the constitutive as the induced enzyme have properties comparable with those of the liver-bone-kidney group. The induced alkaline phosphatase clearly differs from the "constitutive" alkaline phosphatase concerning the effect of high concentrations of L-phenylalanine and the effect of Mg2+ ions. The induced alkaline phosphatase seems to be identical with the enzyme in liver, but the constitutive alkaline phosphatase could not be identified.

Alkaline Phosphatase↗
PubMed1990

[Identification of serum alkaline phosphatase from human bone].

Polyacrylamide gel electrophoresis utilizing sodium dodecyl sulfate followed by specific staining for alkaline phosphatase was accomplished using sera from patients with osteosarcoma, polyostotic fibrous dysplasia, metastatic bone tumor, and idiopathic hyper-alkalinephosphatasemia. Alkaline phosphatase activity of the sera was uniformly demonstrated at a molecular weight of 60,000. L-homoarginine more strongly inhibited the alkaline phosphatase activity than did L-phenylalanine. Alkaline phosphatase activity was markedly inactivated by heating. Regarding substrate specificity, the hydrolysis of p-nitro-phenylphosphate occurred at a lower rate than did that of phenylphosphate. By contrast, the hydrolysis of alpha- and beta-glycerophosphate occurred at a higher rate than did that of phenylphosphate. As seen from the data presented here, the serum alkaline phosphatase samples obtained from these patients with skeletal disorders have several common characteristics.

Alkaline Phosphatase↗