Fetal sex and variations in kinetic properties of neutrophil alkaline phosphatase during the second trimester of normal pregnancy.

A kinetic parameter (the Vm/Km ratio), an index of neutrophil alkaline phosphatase catalytic efficiency, was studied in 36 women with normal pregnancies at 16-20 weeks' gestation. On each blood sample, determinations were achieved on enzyme extracted from maternal granulocytes by monitoring the phosphohydrolytic activity at 400 nm on a spectrophotometer equipped with software for computation of kinetic parameters. Infant sex was recorded at the delivery for all women included in this study. The recent introduction of NAP as a marker for some pathological pregnancies requires a better knowledge of the behaviour of that enzyme in physiological conditions. Data reported focus attention on fetal sex. It appears to be one of the factors involved in variations of kinetic parameters observed in maternal NAP. Sex-linked differences in placental maturation could explain these results.

Inhibition by sodium thiophosphate and L-p-bromotetramisole of neutrophil alkaline phosphatase in normal and trisomy 21 pregnancies.

Alkaline phosphatase concentrations are known to increase in blood neutrophils of normal pregnant women. The main kinetic parameters of this enzyme were analysed and compared in a group of 30 women with normal pregnancies and a group of 11 women whose fetuses had trisomy 21 (Down's syndrome = DS). The subjects were studied at an identical stage of gestation. Significant changes occurred in thermal stability and urea resistance in cases of DS pregnancies. We also investigated the inactivation constants for two chemicals: L-p-bromotetramisole, an uncompetitive inhibitor, and sodium thiophosphate, a competitive inhibitor. Ki measured for the two inhibitors were found to be significantly lower in cases of pathological pregnancies. The patterns observed in inhibition constants extend the biochemical characteristics of the atypical isoenzyme expressed in neutrophils of women with DS pregnancies.

Nuclear localization and characterization of alkaline phosphatase in neutrophils from normal controls and pregnant women.

There were controversial data concerning localization of alkaline phosphatase (AP) in neutrophil nuclei under physiological conditions. In this context, the AP pattern has been determined on nuclei preparations from normal human neutrophils. Blood cells were isolated from 10 healthy adults and from 3 women in the third trimester of an uncomplicated pregnancy. Purity of nuclear suspension was checked by electron microscopy and assay of organelle marker enzymes. Electron microscope cytochemistry and immunocytochemistry studies were carried out on WBC. Enzyme characterization was performed by the usual biochemical procedures. AP was found in nuclear preparations from four of ten normal controls. When present, AP was detected in approximately two-thirds of the nuclei examined, representing an average of 20% of the total cell activity. Conversely, a large amount of nucleus-bound enzyme (55% of total AP activity) was recognized in all pregnant women samples. Biochemical and immunological characteristics clearly differentiate AP forms in the two groups of subjects. Normal controls have an heterogeneous enzyme pattern. AP positive preparations contain a mixture of isoenzymes: a prominent heat labile form and a relatively heat stable minor component. The heat stable fraction displays some properties similar to those previously described in leukocyte AP. Pregnant women express a unique very heat labile isoenzyme identical in its main characteristics to the early placental type.

Effects of uric acid in aqueous phase on neutrophil alkaline phosphatase.

In vitro effects of uric acid (2-6-8 trioxypurine) on purified human neutrophil alkaline phosphatase were studied. A marked activation of the enzyme catalyzed reaction is observed. This activation is dose and pH dependent and not influenced by dialysis. Uric acid can form a stable complex with alkaline phosphatase, whose biochemical characteristics (heat stability, reactivity towards some inhibitors) are significantly modified.

Characterization of alkaline phosphatase in polymorphonuclear neutrophils from normal sheep.

This paper is an attempt to the analysis of the main biochemical characteristics of alkaline phosphatase from sheep polymorphonuclear neutrophils. Ten male adult Romanoff X Berrichon sheep were studied. Alkaline phosphatase was analyzed from cell homogenates, after extraction and solubilization steps. The Vmax and Km values for 4-nitrophenylphosphate at pH = 9.80 were 347.3 +/- 34 IU/ml and 0.7 +/- 0.18 mmol/l, respectively. The pH optimum was 9.80 with 4-nitrophenylphosphate. L-Homoarginine and EDTA, but not L-phenylalanine, inhibited the enzyme. Magnesium above a concentration of 0.5 mmol/l has shown a protective effect against inhibition by 115, 156 and 250 mmol/l urea (final concentration). Sheep neutrophil alkaline phosphatase was found to be very heat-labile. Polyacrylamide gel electrophoresis indicated a single band of activity with a relative mobility similar to that of the slow component of bone and liver isozymes. It is suggested from the above results that sheep neutrophil alkaline phosphatase shares several biochemical properties similar to those of hepatic bone tissue isozyme.

Changes in neutrophil alkaline phosphatase patterns in a case of chronic myelomonocytic leukemia.

In neutrophils from a 75-year-old woman suffering from chronic leukemia, an abnormal alkaline phosphatase (ALP) was observed, characterized by a significant increase in neutrophil alkaline phosphatase (NAP) activity, associated with an ectopic expression of two isoenzymes: a thermolabile ALP similar to the early placental form (or non-Regan variant), and a heat-stable isoenzyme closely related to the Nagao isoenzyme. The presence of these oncodevelopmental NAP isoenzymes in a myeloproliferative syndrome has previously not been reported.

A study of the selective inhibition by urea of neutrophil alkaline phosphatase isoenzymes.

The kinetics of neutrophil alkaline phosphatase (AP) inactivation by urea were examined. In standardized conditions (molarity and pH of buffer, magnesium chloride and urea concentration), monitoring of the enzymatic reaction allows identification of neutrophil AP isoenzymes. This study confirms the heterogeneity of AP in normal human neutrophils.

Genetic variants of human erythrocyte glucose-6-phosphate dehydrogenase: new characterization data obtained by multivariate analysis.

Thirteen variables used in the course of characterization of G6PD variants from forty-one individuals have been submitted to multivariate factorial and cluster analysis. Because of the diagrammatic representation of the analysis, two main findings were made possible. Firstly, the three-dimensional plot of the experimental data gives the advantage of a model of classification which is closely related to the ethnogeographical origin of the subjects, and to the clinical and haematological incidence of the G6PD variants. Secondly, cluster analysis visualizes the distance between the G6PDs examined. In this respect, it was determined that three local original variants associated with acute haemolytic anaemia showed a close relationship and belonged to the same cluster (Gd(-) Toulouse, Gd(-) Muret and Gd(-) Colomiers). Conversely, two non-haemolytic variants (G6PD Luz Saint Sauveur and Lozère) were found to be linked in another remote cluster. The procedure developed in this work promotes a new approach to G6PD characteristics in human genetic studies.