Unconjugated estradiol, estriol and total estriol in maternal peripheral vein, cord vein, and cord artery serum at delivery in pregnancies with intrauterine growth retardation

The levels of unconjugated estradiol (E2), estriol (E3) and total (conjugated plus unconjugated) E3 in maternal vein serum during labor, cord vein serum, and cord artery serum were measured in normal singleton and twin pregnancies with appropriate for dates babies (AFD) and with light for dates babies (LFD). The mean level of total E3 in the maternal vein serum in singleton pregnancy was significantly lower in the LFD group than in the AFD group, but no differences were seen in the mean levels of unconjugated E2 or E3 between the groups. The concentration of unconjugated E2 in the maternal vein serum was significantly higher in the twin group with a large placenta than in the singleton group with a smaller placenta, while the concentration of total E3 in the case of twin pregnancy with LFD was lower than that in singleton pregnancy with AFD but not significantly. No difference in the concentration of total E3 was observed between the cord vein serum and cord artery serum. The present data suggest that the total E3 level in maternal vein serum may be used in evaluating fetal states such as intrauterine growth retardation.     

RNA-protein cross-linking in Escherichia coli ribosomal subunits: localization of sites on 16S RNA which are cross-linked to proteins S17 and S21 by treatment with 2-iminothiolane.

Treatment of E. coli ribosomal subunits with 2-iminothiolane coupled with mild ultraviolet irradiation leads to the formation of a large number of RNA-protein cross-links. In the case of the 30S subunit, a number of sites on 16S RNA that are cross-linked to proteins S7 and S8 by this procedure have already been identified (see ref. 6). Here, by using new or modified techniques for the partial digestion of the RNA and the subsequent isolation of the cross-linked RNA-protein complexes, three new iminothiolane cross-links have been localized: Protein S17 is cross-linked to the 16S RNA within an oligonucleotide encompassing positions 629-633, and protein S21 is cross-linked to two sites within oligonucleotides encompassing positions 723-724 and positions 1531-1542 (the 3'-end of the 16S RNA).     

Interaction of serum proteins with CYP isoforms in human liver microsomes: inhibitory effects of human and bovine albumin,alpha-globulins,alpha-1-acid glycoproteins and gamma-globulins on CYP2C19 and CYP2D6

The effects of serum proteins on the in vitro hydroxylation pathways of mephenytoin (CYP2C19) and debrisoquine (CYP2D6) were studied to enhance the predictability of in vivo drug metabolism from in vitro assays. Both CYP substrates are known to be weakly bound to albumin and the applicability of the free drug hypothesis was further appraised. Since bovine serum albumin (BSA) is used widely in in vitro assays, a comparison between human and bovine proteins was made. Four major serum proteins were studied: albumin, alpha1-acid glycoprotein (AGP), alpha- and gamma-globulins. Human serum albumin (HSA) inhibited both CYP activities about 20% more than BSA. The addition of human alpha-globulins, but not the bovine protein, resulted in marked reduction of 86% and 41% in CYP2C19 and CYP2D6 activities, respectively. This reduction of activity was strikingly greater than the fraction bound (14 and 22%, respectively). The inhibition was of the competitive type and the Ki values of human alpha-globulins on CYP2C19 and CYP2D6 were found to be 0.45% (4.5 mg/ml) and 3.5% (35 mg/ml), respectively. The effect of both human and bovine gamma-globulins on CYP isoforms was negligible. The Ki values of human and bovine AGP for CYP2C19 were 1.84% (420 microM) and 0.93% (210 microM), respectively. For HSA, human alpha-globulins and human and bovine AGP, the strongly decreased CYP activities in vitro cannot be explained by the free drug hypothesis. A direct interaction of these serum proteins with CYP enzymes is postulated. Differential effects of bovine and human serum proteins and CYP specific inhibition were observed.