Partial purification and characterization of a circulating hypertensive factor in spontaneously hypertensive rats.

Parabiosis and cross-circulation experiments with spontaneously hypertensive and normotensive rats gave indications for a previously unidentified circulating hypertensive agent. In this study, plasma from normotensive and hypertensive rats was fractionated and the vasopressor action of the corresponding fractions was measured in the isolated perfused rat kidney. One of three vasoactive fractions obtained by gel filtration (Biol-Gel P2) from hypertensive rats showed a significantly higher activity (increase in perfusion pressure by 1502.9 +/- 438.9 Pa) than that from normotensive rats (increase in perfusion pressure by 505.4 +/- 186.2 Pa, P < 0.01). Further chromatographic separations of this fraction revealed that the hypertensive factor is hydrophilic and has no ionic groups or vicinal diol groups. The molecular mass was estimated by dialysis and the matrix-assisted laser desorption/ionization mass spectrometry to be in the range of 1 kDa. The vasopressor is heat resistant and not degradable with trypsin or carboxypeptidase Y. The vasopressor action was not inhibited with the angiotensin-II-receptor antagonist saralasin, the alpha-receptor antagonist phentolamine, the thromboxane-receptor antagonist carbocyclic thromboxane A2 or the serotonin antagonist ketanserin. The results confirm the existence of a vasopressor factor in the plasma of hypertensive rats and, in a lower concentration, of normotensive rats, which is possibly related to the pathogenesis of essential hypertension. The chromatographic behavior suggests that this factor is different from the parathyroid hypertensive factor described recently.

Detection of fetal trisomies 21 and 18 from maternal blood using triple gradient and magnetic cell sorting.

PROBLEM: The need for an inexpensive and reproducible technique for noninvasive prenatal diagnosis by fetal cell isolation from maternal blood. METHOD: For enrichment of fetal cells we used a combination of triple density gradient and magnetic sorting (MACS) of (anti-CD71) transferrin receptor antibody labeled cells followed by fluorescence in situ hybridization (FISH) with chromosome-specific DNA probes for detection of fetal aneuploidies. We identified 15 cases of fetal trisomy (five cases with a trisomy 18 and ten cases with a trisomy 21) with subsequent chromosome-specific FISH. RESULTS: We found in all of the aneuploid pregnancies that the percentage of cells with three hybridization signals did not overlap with those of normal controls independent from gestational ages and previous invasive procedures. CONCLUSIONS: Our new approach for noninvasive prenatal diagnosis has proven to be reliable in this first series.