Heat-stable Alkaline Phosphatase Activity Research Articles

Reference interval of serum heat-stable alkaline phosphatase activity in pregnant women in Zaria

The study was designed to establish a reference interval for serum heat-stable ALP activity in pregnancy, which is not available in this environment. One hundred (100) apparently healthy pregnant women in their third (3rd) trimester who were attending the antenatal clinic (ANC) of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria were recruited for the study. The serum heat-stable ALP activity was measured using the 4-nitrophenyl phosphate (4-NPP) method introduced in 1946 by Bessey, Lowry and Brock. The reference interval for the serum heat-stable ALP activity was found to be 24-161 IU/L. This was similar to some earlier reports elsewhere. The finding will help in the evaluation/diagnosis of patients with placental insufficiency.

Heat stable and urea resistant alkaline phosphatase in maternal neutrophils from normal and Down syndrome pregnancies

Activity levels of total and placental alkaline phosphatase (AP) were determined in maternal serum and neutrophils of normal and Down syndrome pregnancies. The placental iso-enzyme (PAP) was identified by its relative stability to urea and heat. Significant increase in the activity of all iso-enzymes across gestational stages was observed in maternal sera of 28 normal pregnancies. However, in the neutrophil extracts of the same blood samples no differences were detected between trimesters. Another set of experiments was aimed at finding diagnostic differences of PAP activity in maternal neutrophils of normal and trisomy 21 affected pregnancies. No differences of heat stable AP activity were found in maternal samples of 19 normal and 19 Down syndrome affected pregnancies. Urea resistant AP proportions were also similar when measured after 40 minutes of exposure (13 samples in each group). However, a marginally significant increase was observed in the mean value of the Down syndrome affected samples, after 60 minutes of urea treatment. In view of the above results we conclude that neutrophil AP activity is not as yet a useful marker for the screening of trisomy 21 fetuses.

Heat-stable and immunoreactive placental alkaline phosphatase in maternal serum from Down's syndrome and trisomy 18 pregnancies.

Placental alkaline phosphatase (ALP) activity was investigated in second-trimester maternal sera from 37 pregnancies with Down's syndrome, 28 pregnancies with trisomy 18, and in a series of 497 controls using a fluorimetric heat inactivation assay and specific immunoassay. After conversion of individual analyte values to multiples of the normal gestational median (MOM), no significant differences in total or placental ALP activities were found in the trisomy 21 or trisomy 18 cases (P > 0.01). In the Down's syndrome pregnancies, total ALP activity was 0.93 MOM, heat-stable ALP activity was 1.09 MOM, and placental ALP (by immunoassay) 0.96 MOM. In the trisomy 18 cases, total ALP activity was 0.90 MOM, heat-stable ALP activity was 0.79 MOM, and placental ALP (by immunoassay) 0.94 MOM. We conclude that neither total nor placental ALP activity is a useful marker for Down's syndrome or trisomy 18 screening.

Fluorometric analysis of heat-stable alkaline phosphatase activity in human serum by means of high-performance liquid chromatography

A method is proposed for the determination of heat-stable alkaline phosphatase (HSAP) in serum. It comprises the following steps. The serum is heat-inactivated at 65°C and the residual alkaline phosphatase is allowed to react with Naphthol AS-MX phosphate. After stopping the reaction by acetone, the liberated Naphthol AS-MX is measured fluorometrically using high-performance liquid chromatography (HPLC). This method can be applied to cancer-screening in clinical examination. It is sensitive and rapid as compared with existing methods. Linearity, accuracy and detection limit have been examined (linearity 0–2190 ng Naphthol AS-MX; coefficient of variation ≈7%; recovery ≈80%).

Stimulation of human chorionic gonadotropin secretion by glucocorticoids

The effects of glucocorticoids on hormone secretion by human placenta in organ culture were studied. The addition of cortisol resulted in a fourfold increase in human chorionic gonadotropin (hCG) secretion over that in untreated cultures after 144 hours' incubation (P < 0.05), and a twofold increase in hCG was observed in the presence of cortisone (P < 0.01). Dexamethasone stimulated hCG secretion in a dose-response manner (r = 0.9542; P < 0.01). Progesterone, which suppresses hCG under these conditions, decreased the cortisol-enhanced secretion of hCG (r = −0.9794; P < 0.01). No change in the secretion of human chorionic somatomammotropin was observed, but glucocorticoids increased heat-stable alkaline phosphatase activity (P < 0.001). The physiologic significance of glucocorticoid effects on placental hormone synthesis is ducussed.

Differential determination of the heat-stable alkaline phosphatase activity in serum.

A procedure for the determination of the heat-stable alkaline phosphatase activity in serum was developed by using antibody-conjugated paper disks and inhibition by sodium thiocyanate. The placental alkaline phosphatase adsorbed on a paper disk conjugated with antibody was completely inhibited by 3M sodium thiocyanate, but the activity of intestinal alkaline phosphatase adsorbed on the paper disk was unaffected by 3M sodium thiocyanate. The results obtained by the proposed method showed a good correlation with those obtained by the heat-inactivation method (γ=0.991). These results strongly suggest that the proposed method can be utilized as a routine clinical test for the determination of serum placental-type alkaline phosphatase, i. e., placental, Regan, Nagao and Kasahara isoenzymes, from patients with cancer.

Maternal serum alkaline phosphatase and fetal maturity.

Total as well as heat stable alkaline phosphatase activity was determined in sera of 70 normal pregnant mothers. Rise in activity was observed with advancement of gestation and was due to increased concentration of heat stable fraction. Statistically significant differences in levels between various gestational age groups suggest the assay of this enzyme for assessment of fetal maturity. Total alkaline phosphatase activity of 15 K.A. units/dl or more, with more than 50% of it being heat stable fraction, indicated a mature fetus (37 weeks or more gestation).

The Ontogony of the Human Placental Glucocorticoid Receptor and Inducibility of Heat-Stable Alkaline Phosphatase*

The human placenta was found to contain a cytosol receptor for glucocorticoids. The concentration of this receptor in term placenta was 27-fold higher than that found in cytosol from first trimester placenta. The levels of cytosol glucocorticoid receptor in three trophoblastic cell lines (JAr, BeWo, and JEG) were also determined and all were found to be low. The ability of prednisolone, a potent glucocorticoid, to stimulate heat-stable alkaline phosphatase activity found in these cells was tested. Although control experiments demonstrated that the conditions were adequate to stimulate HeLa cell alkaline phosphatase, none of the trophoblastic lines responded to prednisolone administration. This result may be explained by the observation that the JAr cells lacked any detectable glucocorticoid receptor and the receptor levels in cytosol prepared from JEG and BeWo cells were 12% and 2%, respectively, of those measured in HeLa cytosol. Our studies also suggest that the increase in serum levels of heat-stable alkaline phosphatase observed during pregnancy may reflect increasing placental sensitivity to glucocorticoids as a result of increased receptor levels.

Characteristics of alkaline phosphatase from two continuous lines of human choriocarcinoma cells

Several characteristics of human choriocarcinoma alkaline phosphatase have been studied. BeWo and Jar choriocarcinoma lines each contain heat-stable alkaline phosphatase activity with characteristics similar to the D-variant term placental isoenzyme. The activity is also similar to the Nagao enzyme found in many malignancies. Each choriocarcinoma also has heat-labile alkaline phosphatase activity with characteristics similar to the enzyme found in normal first-trimester placenta. Neither BeWo alkaline phosphatase could be stimulated with cortisol. Both BeWo alkaline phosphatase activities could be stimulated with methotrexate and actinomycin D.

Alkaline phosphatase modulation by osmolality changes during the growth cycle of KB cell cultures.

Growing KB cells in hyperosmolar medium causes in reduction in total alkaline phosphatase activity associated with a decrease in the proportion of the heat-labile and an increase of the heat-stable enzyme components. In standard medium enzyme activity increases progressively during a 6-day growth cycle and the proportion of heat-stable activity remains constant. In hyperosmolar medium, activity increases only during the initial 24 hr after the change in osmolality and then levels off, but the heat-stable alkaline phosphatase activity increases 7-fold within 48 hr. The transmission in thermostability is discernible 24 hr after increasing the osmolality of the medium and toward the end of a growth cycle most of the activity is heat-stable.

Quantitative estimation of heat-stable alkaline phosphatase activity in dried blood stains and its application to the forensic diagnosis of pregnancy.

The placental isoenzyme of alkaline phosphatase is characterized by heat stability (56° C for 30 min). This paper describes a new technique for the forensic diagnosis of pregnancy from blood stains, based on the fact that in serum of pregnant women in the latter half of pregnancy the heat-stable alkaline phosphatase activity rises markedly. In this study the total and heat-stable alkaline phosphatase activities were quantitatively assayed in blood stains of various origins by the method of Bessey-Lowry-Brock with the use of disodium p-nitrophenyl phosphate as substrate. Our results indicate that the principle herein reported may be helpful in the diagnosis of pregnancy from blood stains.

Serum heat-stable alkaline phosphatase in pregnancy

Serum heat-stable alkaline phosphatase activity was followed throughout pregnancy in 143 women. At the end of the study the charts of the patients were inspected, and the pregnancies were classified as normal or abnormal (mild pre-eclamptic, pre-eclamptic, severe pre-eclamptic, prediabetic, diabetic, and hypertensive). Of the abnormal pregnancies, there were only sufficient numbers of pre-eclamptic patients for statistical analysis. No significant difference was found between the mean values of heat-stable alkaline phosphatase for pre-eclamptic and normal patients. The enzyme changes in individual subjects did not reveal any consistent difference between normal and abnormal patients at any time during pregnancy.