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N Cester

Publications and source records attributed to N Cester.

47 records · Page 3Linked to original sources
PubMed1989

Molecular alterations induced by hypertension in pregnancy on syncythiotrophoblast plasma membranes from human placenta.

To evaluate the possible functional relationships between hypertensive status and syncythiotrophoblast plasma membrane behaviour we have carried out a freeze-fracturing and biochemical investigation to assess: 1) ultrastructurally, relations between number and diameter of Intramembrane Particles (IMP) and hypertensive conditions; 2) biochemically, actin content of microvilli in this pathological status. Our data in vitro show a decrease of IMP in hypertension before and after Ca++ addition and a decrease of actin in microvilli of hypertensive placenta. These observations seem to be in agreement with the hypothesis of a possible structural immaturity in hypertensive placenta and may represent morphological signs of placental insufficiency.

Actins↗
PubMed1988

Abnormal membrane cation transport in pregnancy-induced hypertension.

An abnormality of sodium handling has been suggested as one of the mechanisms responsible for the development of pregnancy-induced hypertension. We analysed the plasma and urinary concentrations, and the intraerythrocyte activities of Na and K, and the RBC membrane Na+/K+-ATPase activity of 77 hypertensive and 133 normal pregnant women. Umbilical cord blood of infants from 21 hypertensive and 28 control women was studied. The Na+/K+-ATPase activity was determined by measuring the inorganic phosphate released by incubation in a reaction medium in the presence and absence of K ions or ouabain. The intra-erythrocyte sodium and potassium activities were measured by ion-selective electrode analysis of the haemolysates, after washing the RBCs in 110 mmol/l MgCl2. We found a significant increase in intracellular sodium and a reduction in Na+/K+-ATPase activity in the hypertensive women in comparison with the control subjects during pregnancy. No difference was observed in early puerperium. Cord blood from infants of pregnancy-induced hypertensive women showed an increase in intracellular Na+ activity and a decrease in the erythrocyte membrane Na+/K+-ATPase activity in comparison with cord blood samples from control subjects. The observed abnormalities in the plasma membrane sodium transport may play a major role in the pathophysiology of pregnancy-induced hypertension.

Biological Transport↗
PubMed1988

Effect of general anesthesia on syncytiotrophoblast plasma membranes from human placenta.

This investigation shows that a general anesthetic produces similar effects in vivo and in vitro. Anesthesia with a barbituric drug, Thiopental, induces an increase in membrane fluidity and a decrease in the activity of acetylcholinesterase in syncytiotrophoblast plasma membranes (SPM) obtained from placentas after caesarean section. The same effects can be reproduced in vitro after anesthetic addition to the isolated plasma membranes. Morphological and freeze-fracturing studies also suggest that membrane protein components are affected by anesthetics.

Acetylcholinesterase↗
PubMedDate not supplied

Effect of Ca2+ on structure and fluidity of microvillus membranes of human placenta.

This investigation shows the effect of a Ca2+ addition on the structural and physiochemical properties of microvillus plasma membranes obtained from human placenta. Ca2+ addition induces an increase in microviscosity, as shown by the increase of order parameter and rotational correlation time of 5- and 16-doxylsterate derivatives and by the increase of fluorescence polarization of diphenylhexatriene. All the effects were obtained in a wide temperature range. The morphometric analysis of the ultrastructural images shows that the vesicle profiles of syncytiotrophoblast membranes decrease both area and form factor (FF) in the presence of Ca2+ with respect to the controls. The freeze-fracture results also show that Ca2+ induces an enhanced tendency to IMP clusterization. The Ca2+-induced changes were observed in both E and P faces. Our results underline the important role of Ca2+ in the cell membrane structure per se and in modulating interactions between cytoplasmic and extracellular microenvironments. The results of morphometric analysis of the ultrastructural images agree with biochemical data showing an increased stability induced by calcium on plasma membranes.

Calcium↗