ABSTRACT
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.
Subject(s)
Alkaline Phosphatase/blood , Gestational Age , Neutrophils/enzymology , Sex Characteristics , Adult , Female , Humans , Kinetics , Male , Pregnancy , Regression AnalysisABSTRACT
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.
Subject(s)
Alkaline Phosphatase/antagonists & inhibitors , Down Syndrome/blood , Enzyme Inhibitors/pharmacology , Neutrophils/drug effects , Pregnancy Complications/blood , Pregnancy/blood , Adult , Binding, Competitive , Bone and Bones/enzymology , Case-Control Studies , Female , Humans , Kidney/enzymology , Liver/enzymology , Maternal Age , Neutrophils/enzymology , Phosphates/pharmacology , Pregnancy, High-Risk , Tetramisole/analogs & derivatives , Tetramisole/pharmacologyABSTRACT
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.
