Identification and tissue localization of an eosinophil 17 kDa protein accumulating in rat uterus upon estradiol treatment.

In a previous paper (J. Steroid Biochem. 29 (1988) 475-480), the isolation of a 17 kDa protein that was dramatically induced in the uterus of estrogen-treated spayed rats was presented.

Racemic LTA4 methyl ester bioconversion into LTC4 methyl ester by various glutathione S-transferases.

It has been shown that various glutathione transferases can synthesize leukotriene C4, or its methyl ester, from glutathione and leukotriene A4. We questioned whether the same enzymes could be used to resolve racemic leukotriene A4 methyl ester (more easily prepared than the optically active enantiomer) and to produce leukotriene C4 methyl ester selectively. We present in this paper a study of the enantioselectivity of some rat liver glutathione transferase isozymes and of the glutathione transferase of human placenta for the leukotriene A4 methyl ester isomers.

Inhibition of platelet aggregation by human placenta.

Human placental cytosol inhibits platelet aggregation induced by high doses of collagen. The aim of this study was to investigate whether this anti-aggregating activity was caused only by the presence of various activities already described in the placenta (an ADP-consuming enzyme, a fatty acid cyclooxygenase inhibitor, and a thromboxane synthetase inhibitor) or whether another factor was present. Heating the cytosol at 50 degrees C for 6 min destroyed the inhibitor of collagen-induced aggregation.

The human placental anti-aggregating factor is neither prostacyclin, nor a prostacyclin metabolite.

Using PGH2 as substrate, we have previously demonstrated that human placenta synthesizes mainly PGE2, TxB2 and PGD2(1,2). Other reports have shown that placental tissue generates a substance which inhibits ADP-induced platelet aggregation and which was supposed to be PGI2 (3). The present study indicates that the stability of that substance is different from the stability of prostacyclin (released by umbilical artery pieces).