Ashi Daftary

Selective Overexpression of the Hypoxia-Inducible Transcription Factor, HIF-2α, in Placentas from Women with Preeclampsia

Abstract Transcription factors orchestrate the development of extraembryonic tissues. Because placental hypoxia likely plays an important role in both normal and abnormal placentation, we have been investigating the hypoxia-inducible transcription factors (HIFs) in the human placenta. In this report, we focus on the placentas from women with preeclampsia. Because the placenta is a large, heterogeneous organ, we employed a systematic and unbiased approach to placental sampling, and our results are based on the analyses of eight biopsy sites per placenta. We observed no significant differences in HIF-1α or -2α mRNA expression between normal term and preeclamptic placentas. Nor was HIF protein expression significantly different, with the notable exception of HIF-2α, which, on average, was increased by 1.7-fold in the preeclamptic placentas (P < 0.03 vs. normal term placentas). Considering all 48 paired placental biopsy sites (eight sites each for six normal term and six preeclamptic placentas), HIF-2α protein levels in the preeclamptic placentas exceeded those in the normal term placentas in 39, or 81%, of the paired sites (P < 0.0013). The HIF-2α immunoreactivity was mainly located in the nuclei of the syncytiotrophoblast and fetoplacental vascular endothelium in the preeclamptic villous placenta. To control for the earlier gestational age of the preeclamptic placentas, an additional group of placentas from preterm deliveries without preeclampsia were also evaluated. The HIF protein expression was comparable in these preterm specimens and the normal term placentas. We conclude that protein expression of HIF-2α, but not of HIF-1α or -1β, is selectively increased in the preeclamptic placenta. The molecular mechanism(s) of this abnormality as well as the genes affected downstream are currently under investigation. To our knowledge, this is the first report of abnormal HIF-2α expression in human disease other than cancer.

Associations of maternal and umbilical cord hormone concentrations with maternal, gestational and neonatal factors (United States).

Objective: Risks of some cancers in adults have been associated with several pregnancy factors, including greater maternal age and birth weight. For hormone-related cancers, these effects are hypothesized to be mediated through higher in utero estrogen concentrations. In addition, racial differences in pregnancy hormone levels have been suggested as being responsible for differences in testicular and prostate cancer risk by race. However, data on hormonal levels related to these characteristics of pregnancy are sparse, particularly those from studies of the fetal circulation. Methods: Estrogen and androgen concentrations were measured in maternal and umbilical cord sera from 86 normal, singleton pregnancies. Results: Birth size measures (weight, length and head circumference) were positively correlated with maternal estriol (r = 0.25–0.36) and with cord DHEAS concentrations (r = 0.24–0.41), but not with estrogens in cord sera. Maternal age was inversely correlated with maternal DHEAS, androstenedione and testosterone concentrations (r = −0.30, −0.25 and −0.30, respectively), but uncorrelated with estrogens in either the maternal or cord circulation. Black mothers had higher androstenedione and testosterone concentrations than white mothers, however, there were no racial differences in any of the androgens in cord sera. Cord testosterone concentrations were higher in mothers of male fetuses, while both maternal and cord concentrations of estriol were lower in these pregnancies. Conclusions: These data demonstrate associations between hormone concentrations and pregnancy factors associated with offsprings cancer risk, however, the hormones involved and their patterns of association differ by whether the maternal or fetal circulation was sampled. Hormone concentrations in the fetal circulation in this study are not consistent with the hypothesis that greater estrogen concentrations in high birth weight babies mediate the positive association with breast cancer risk observed in epidemiologic studies, or with the hypothesis that higher testosterone exposure in the in utero environment of black males explains their higher subsequent prostate cancer risk.

First trimester adipocytokine concentrations and risk of developing gestational diabetes later in pregnancy.

Objective  Adipocytokines are important regulators of insulin resistance. The aim of this study was to compare maternal adipocytokines in early pregnancy among women diagnosed with and without gestational diabetes (GDM) months later.

Neonatal adiposity following maternal treatment of gestational diabetes with glyburide compared with insulin

OBJECTIVE We hypothesized that body composition would be similar among neonates of women with gestational diabetes (GDM) treated with glyburide or insulin. STUDY DESIGN Women with GDM requiring medical therapy were randomized to insulin or glyburide. The primary outcome was percent neonatal fat mass measured by total body electrical conductivity. Secondary outcomes included anthropometrics, glycemic control, and biomarkers. Statistical analysis included Student t test, chi(2), and regression modeling. RESULTS Eighty-two neonates underwent postnatal measurements. Baseline factors were not different by group. Neonatal percent fat mass did not differ between treatment groups (11.2 +/- 4.2 vs 12.8 +/- 5.7). Fat mass, body mass index, ponderal index, skinfold sum, and arm fat area were not different when analyzed by intent to treat or actual treatment group. Cord concentrations of biomarkers were also similar. CONCLUSION There was no difference in neonatal adiposity in infants of women treated for GDM with glyburide or insulin.

S-Nitrosoalbumin–Mediated Relaxation Is Enhanced by Ascorbate and Copper: Effects in Pregnancy and Preeclampsia Plasma

S-nitrosoalbumin (SNO-Alb) is a major reservoir of releasable nitric oxide (NO) in plasma. In preeclampsia, a pregnancy-specific disorder associated with endothelial dysfunction, we previously found significant elevations in plasma SNO-Alb concentrations and decreased plasma ascorbate (Asc) levels. This increased SNO-Alb may result from low-plasma Asc if Asc, along with transition metals (eg, copper [Cu]) are necessary for release of NO from S-nitrosothiols. We propose that vasodilator effects of SNO-Alb, mediated by release of NO, are fully realized only when Asc/Cu availability is sufficient. Relaxation responses to SNO-Alb or the control reduced human serum albumin (SH-Alb), and responses to pooled plasma from normal or preeclamptic pregnancies were examined in isolated mouse arteries. Arteries preconstricted with phenylephrine were exposed to SNO-Alb or SH-Alb at physiologically relevant concentrations. When free Cu was added in excess (10 &mgr;mol/L), NO release was not dependent on Asc. However, when Cu was added at lower (physiological) levels, NO release was dependent on Asc. The addition of Asc and Cu to SNO-Alb stimulated vasodilatory responses in isolated arteries >90%, whereas no change in the SH-Alb (5%) response was observed. Preeclampsia plasma with higher levels of SNO-Alb caused arteries to relax 44.1±4.7%, whereas normal pregnancy plasma caused 11.9±4.2% relaxation (P=0.007). These data indicate that SNO-Alb alone or in plasma can act as a potent vasodilator, and that sufficient Asc/Cu promotes this action. We suggest that the higher circulating levels of SNO-Alb, in women with preeclampsia, reflect a deficiency in Asc/Cu-mediated release of NO from SNO-Alb.

Proteasomal Activity in Placentas from Women with Preeclampsia and Intrauterine Growth Restriction: Implications for Expression of HIF-α Proteins

Hypoxia-inducible transcription factor-1alpha and -2alpha (HIF-alpha) proteins and regulated genes are increased in preeclamptic (PE) placentas. Although placental hypoxia likely stabilizes HIF-alpha proteins, we previously reported that there is also a defect in oxygen-dependent reduction of HIF-alpha proteins in PE relative to normal pregnant (NP) placentas that could contribute to their over-expression. After a 4-h exposure to 2% oxygen, placental villous explants were exposed to 21% oxygen over 90 min. As assessed by Western analysis, the defective oxygen-dependent reduction of HIF-1alpha protein in villous explants from PE placenta was unaffected by the protein synthesis inhibitor, cycloheximide. However, after incubation with the proteasomal inhibitor, clasto-lactacystin, oxygen-dependent reduction of HIF-1alpha protein was markedly and similarly impaired in the villous explants from both normal and PE placentas. Thus, impairment of protein degradation rather than increased synthesis causes inadequate oxygen-dependent reduction of HIF-1alpha protein in PE placentas. Immunoprecipitation studies revealed comparable association of HIF-1alpha with von Hippel Lindau (VHL) protein in placentas from NP and PE women. Furthermore, prolyl hydroxylase-3 protein was appropriately upregulated in the PE placentas as determined by Western analysis paralleling the increases of HIF-alpha proteins. These results suggest that molecular events leading to the formation of the HIF-1alpha:VHL:ubiquitin ligase complex are most likely not impaired in PE placentas. Finally, proteasomal trypsin, chymotrypsin, and peptidyl glutamyl-like activities were significantly reduced by approximately 1/3 in PE placentas by using specific peptide substrates coupled to a fluorescent tag. Unexpectedly, however, they were even further decreased in placentas from normotensive women delivering growth restricted babies >37 weeks gestation-placentas which do not have elevated HIF-alpha proteins. In conclusion, accumulation of HIF-alpha proteins in PE placentas may occur as a consequence of both increased formation secondary to relative ischemia/hypoxia and reduced degradation after reperfusion/oxygenation consequent to proteasomal dysfunction. In contrast, in placentas from normotensive women delivering growth restricted babies >37 weeks gestation, proteasomal activity, albeit markedly reduced, is adequate to cope with degradation of HIF-alpha proteins, which have not been increased by an hypoxic environment.

Dynamic postural stability during advancing pregnancy.

UNLABELLED Pregnant women are at an increased risk of experiencing a fall. Numerous anatomical, physiological, and hormonal alterations occur during pregnancy, but the influence of these factors on dynamic postural stability has not been explored. The purpose of this study was to examine dynamic postural stability in pregnant women during their second and third trimesters as well as in a group of non-pregnant control women. METHODS Eighty-one women (41 pregnant, 40 controls) participated stood on a force plate that translated anteroposteriorly at small, medium, and large magnitudes. Reaction time and center of pressure (COP) movement during the translations were analyzed. Trimester, perturbation direction, and perturbation magnitude were the independent variables in a mixed-model analysis of variance on each of the following dependent variables: reaction time, initial sway, total sway, and sway velocity. RESULTS Reaction time to the perturbation was not significantly different between the groups. Initial sway, total sway, and sway velocity were significantly less during the third trimester than during the second trimester and when compared to the non-pregnant controls (P<0.05). No differences were found in any of the measures between the pregnant women in their second trimesters and the control group. CONCLUSION Alterations in sway responses to perturbations are seen in the third trimester in healthy women with uncomplicated pregnancies. Further study is needed to examine the biomechanical and physiological reasons behind this altered dynamic postural stability.

Homocysteine and Folic Acid Are Inversely Related in Black Women With Preeclampsia

Black women have an increased risk of preeclampsia compared with white women. Plasma homocysteine is increased in preeclampsia. Homocysteine concentrations are affected by nutritional deficiencies, particularly decreased folic acid and B12, leading to increased homocysteine. Previous studies have reported racial differences in nutritional intake including folic acid. Therefore, we investigated whether there were racial differences in plasma homocysteine, folic acid, and vitamin B12 among women with preeclampsia. We tested for an association between homocysteine and folic acid and B12, and we hypothesized an inverse relationship of homocysteine and folic acid in preeclampsia, more so in black women in whom preeclampsia developed. Black women with preeclampsia (n= 26) had elevated homocysteine concentrations (8.7±1.4 μmol/L) compared with black women with normal pregnancy (n= 52, 7.6±0.5 μmol/L), white women with preeclampsia (n= 34, 7.5±0.6 μmol/L), and white women with normal pregnancy (n= 48, 5.5±0.3 μmol/L). Folic acid concentrations were lower in black women (14.1±0.8 ng/mL) compared with white women (18.5±0.9 ng/mL, P < 0.01). However, plasma homocysteine was inversely related to folic acid only among black women with preeclampsia (r = −0.23, P = 0.01). These racial differences may have implications for the higher rates of preeclampsia in this group and may have long-term implications for future cardiovascular risk. Racial differences in diet, adherence to folic acid supplementation, or interactions of nutritional and maternal factors warrant further study by race and pregnancy status.

Dynamic postural stability in pregnant fallers and non-fallers

Please cite this paper as: McCrory J, Chambers A, Daftary A, Redfern M. Dynamic postural stability in pregnant fallers and non‐fallers. BJOG 2010;117:954–962.

Ground reaction forces during gait in pregnant fallers and non-fallers

UNLABELLED Pregnant women are at a high risk of experiencing a fall. To our knowledge, ground reaction forces (GRFs) in pregnant fallers and non-fallers have not been reported. PURPOSE The purpose of this study was to examine the effects of pregnancy and fall history on GRFs during walking. METHODS Forty one pregnant subjects in the mid 2nd and 3rd trimesters (pregnant fallers: n=15, pregnant non-fallers: n=14), and 40 control women walked at a freely chosen walking speed along an 8m walkway. A force plate, hidden in the walkway, was used to collect GRFs (1080Hz). Kinematic data (120Hz) were collected from a marker placed on the lumbar spine to estimate walking velocity. GRF variables included mediolateral Center of Pressure (COP) excursion, and GRFs normalized to body mass. A two factor ANOVA (trimester x fall group) was used to compare subject demographics, and walking velocity (α=0.05). A two factor ANCOVA (trimester×fall group, covariate: velocity) was performed to examine other GRF variables (Bonferroni corrected α=0.006) and the mediolateral COP excursion (α=0.05). RESULTS Walking velocity was greater in the control group (p<0.05). No differences were seen in the GRFs or COP movement between trimesters or between pregnant fallers and non-fallers. CONCLUSIONS When walking velocity was considered in the statistical model, ground reaction forces are essentially unchanged by pregnancy.