Is a sFlt-1/PlGF cutoff of 38 suitable to predict adverse outcomes in pregnancies with abnormal uterine artery Doppler velocimetry in the second trimester?

OBJECTIVE

To determine the optimal cutoff value for the soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio to predict maternal and fetal adverse events in pregnancies with uterine artery Doppler scans results above the 95th percentile in the late second trimester.

STUDY DESIGN

Retrospective, observational cohort study on 116 asyntomatic patients with abnormal uterine artery Doppler scans at gestational week 25. The sFlt-1/PlGF ratio was determined within the weeks 25 to 29 of gestation and ROC curve analysis performed. The diagnostic validity of different cutoff values to predict severe maternal and fetal complications, i.e. preeclampsia, fetal growth restriction, placental abruption, and fetal death, was analyzed.

MAIN OUTCOME MEASURES

An ideal cutoff for sFlt-1/PlGF ratios in pregnancies with abnormal uterine artery Doppler in the second trimester.

RESULTS

Applying a cutoff point of 38, the area under the ROC curve was 0.89, generally considered low risk in fetal and maternal complication prediction. The sensitivity was 32.1%, the specificity 98.4%, the positive predictive value (PPV) 94.4%, and the negative predictive value (NPV) 63.3%. A cutoff value of 10, leading to the highest Youden index, performed best at detecting overall complications, increasing sensitivity to 69.8% and the NPV to 76.8%. at the cost of a reduced specificity and PPV.

CONCLUSIONS

In pregnancies with abnormal uterine artery Doppler in the second trimester, an sFlt-1/PlGF cutoff value greater than equal to 38 improves its predictive power for adverse events.

Modulation of epidermal growth factor receptor phosphorylation by endogenously expressed gangliosides

The effect of changing the ganglioside composition of Chinese hamster ovary K1 cells on the function of the epidermal growth factor receptor (EGFr) was examined by studying the signalling pathway generated after the binding of epidermal growth factor (EGF) both in cells depleted of glycosphingolipids by inhibiting glucosylceramide synthase activity and in cell lines expressing different gangliosides as the result of stable transfection of appropriate ganglioside glycosyltransferases. After stimulation with EGF, cells depleted of glycolipids showed EGFr phosphorylation and extracellular signal-regulated protein kinase 2 (ERK2) activity as parental cells expressing GM3 [ganglioside nomenclature follows Svennerholm (1963) J. Neurochem. 10, 613-623] or as transfected cells expressing mostly GM2 and GD1a as the result of stable transfection of UDP-GalNAc:LacCer/GM3/GD3 N-acetylgalactosaminyltransferase. However, cells stably transfected with CMP-NeuAc:GM3 sialyltransferase and expressing GD3 at the cell surface showed both decreased EGFr phosphorylation and ERK2 activation after stimulation with EGF. Results suggest that changes in the ganglioside composition of cell membranes might be important in the regulation of the EGF signal transduction.

GM3 alpha2,8-sialyltransferase (GD3 synthase): protein characterization and sub-golgi location in CHO-K1 cells

GD3 synthase (Sial-T2) is a key enzyme of ganglioside synthesis that, in concert with GM2 synthase (GalNAc-T), regulates the ratio of a- and b-pathway gangliosides. In this work, we study the sub-Golgi location of an epitope-tagged version of chicken Sial-T2 transfected to CHO-K1 cells. The expressed protein was enzymatically active both in vitro and in vivo and showed a molecular mass of approximately 47 or approximately 95 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence or absence of, respectively, beta-mercaptoethanol. The 95-kDa form of Sial-T2 was also detected if the protein was retained in the endoplasmic reticulum (ER) due to impaired glycosylation, indicating that it was formed in the ER. Confocal immunofluorescence microscopy showed Sial-T2 localized to the Golgi complex and, within the organelle, partially co-localizing with the mannose-6-phosphate receptor, a marker of the trans-Golgi network (TGN). In cells treated with brefeldin A, a major fraction of Sial-T2 redistributed to the ER, even under controlled expression to control for mislocalization due to protein overloading. In experiments of incorporation of sugars into endogenous acceptors of Golgi membranes in vitro, GD3 molecules formed by incubation with CMP-NeuAc were converted to GD2 upon incubation with UDP-GalNAc. These results indicate that Sial-T2 localizes mainly to the proximal Golgi, although a fraction is located in the TGN functionally coupled to GalNAc-T. Consistent with this, most of the enzyme was in an endoglycosidase H (Endo-H)-sensitive, neuraminidase (NANase)-insensitive form. A minor secreted form lacking approximately 40 amino acids was Endo-H-resistant and NANase-sensitive, indicating that the cells were able to process N-glycans to Endo-H-resistant forms. Taken together, the results of these biochemical and immunocytochemical experiments indicate that in CHO-K1 cells, most Sial-T2 localizes in the proximal Golgi and that a functional fraction is also present in the TGN.

Mouse beta 1,3-galactosyltransferase (GA1/GM1/GD1b synthase): protein characterization, tissue expression, and developmental regulation in neural retina

The composition of cell surface gangliosides is largely dependent on the relative activities of Golgi resident glycosyltransferases. In the brain of birds and mammals, complex gangliosides (GM2, GM1, GD1a, GD1b, GT1b) abound at late stages of development and in the adult, due to the relatively high activities of the UDP-GalNAc:LacCer/GM3/GD3 beta 1,4-N-acetylgalactosaminyltransferase (GalNAc-T) and the UDP-Gal: GA2/GM2/GD2 beta 1, 3-galactosyltransferase (Gal-T2) relative to that of CMP-NeuAc:GM3 alpha 2,8-sialyltransferase (Sial-T2). Unlike brain, the mature mammalian neural retina abundantly expresses the simple ganglioside GD3, in relation to complex gangliosides, due to the low activity of GalNAc-T and Gal-T2 relative to Sial-T2. Here we describe the isolation and characterization of a mouse Gal-T2 cDNA that drives the synthesis of an epitope-tagged protein of molecular mass 43 kDa, which was enzymatically active and localized to the Golgi complex in transfected cell lines. Using this cDNA as a probe, it was found that Gal-T2 is coded by a single gene located in chromosome 17, and that the coding sequence is contained in a single exon. The expression of the specific Gal-T2 mRNA (approximately 1.8 kb) was highest in testis, which also showed elevated Gal-T2 activity. In the postnatal neural retina, Gal-T2 mRNA increased after day 3, maintained high levels of expression by days 4-7, and then decreased to initial values by day 10. The developmental pattern of mRNA expression was temporally coincident with that of Gal-T2 activity expression, indicating that this enzyme is under transcriptional control in the neural retina.

Changes in the plasma levels of androstenedione, dehydroepiandrosterone and cortisol after stimulation with ACTH and hCG and suppression with dexamethasone during male puberty

Cortisol, androstenedione (Δ4) and dehydroepiandrosterone (DHEA), were evaluated by RIA in a group of 34 adolescent boys, grouped according to genital size. Basal blood samples were taken and 2 mg of dexamethasone administered (12 p.m.). Further plasma samples were taken at 9 a. m. and 250 μg of ACTH injected. Additional samples were drawn after 60 and 120 min. After a lapse of two days 5000 IU of hCG was administered every day for four days and blood samples were taken after the second and fourth injection.

After stimulation with ACTH and suppression with dexamethasone the levels of cortisol were higher and lower, respectively, (P < 0.001) than the basal values. No statistical differences were obtained after the administration of hCG. The levels of Δ4 and DHEA clearly decreased after the administration of dexamethasone and markedly increased after stimulation with ACTH. However, after administration of hCG the levels of both steroids rose but those of the latter did not increase as steeply as those of the former.

With regard to the degree of response of the three steroids in relation to the pubertal stages we noted that cortisol showed a steady response at all stages, while Δ4 and DHEA in contrast, showed a more marked response at stages IV and V than at stages I and II.

These results indicate the primary role that the adrenal glands and the testes play in the rise of levels of DHEA and Δ4 during pubertal development.