Vasilis Sitras

Differential placental gene expression in severe preeclampsia.

We investigated the global placental gene expression profile in severe preeclampsia. Twenty-one women were randomly selected from 50 participants with uncomplicated pregnancies to match 21 patients with severe preeclampsia. A 30K Human Genome Survey Microarray v.2.0 (Applied Biosystems) was used to evaluate the gene expression profile. After RNA isolation, five preeclamptic placentas were excluded due to poor RNA quality. The series composed of 37 hybridizations in a one-channel detection system of chemiluminescence emitted by the microarrays. An empirical Bayes analysis was applied to find differentially expressed genes. In preeclamptic placentas 213 genes were significantly (fold-change>or=2 and p<or=0.01) up-regulated and 82 were down-regulated, compared with normal placentas. Leptin (40 fold), laeverin (10 fold), different isoforms of beta-hCG (3-6 fold), endoglin (4 fold), FLT1 (3 fold) and FLT4 (2 fold) were up-regulated. PDGFD was down-regulated (2 fold). Several differentially expressed genes were associated with Alzheimer disease, angiogenesis, Notch-, TGFbeta- and VEGF-signalling pathways. Sixteen genes best discriminated preeclamptic from normal placentas. Comparison between early- (<34 weeks) and late-onset preeclampsia showed 168 differentially expressed genes with oxidative stress, inflammation, and endothelin signalling pathways mainly involved in early-onset disease. Validation of the microarray results was performed by RT-PCR, quantitative urine hCG measurement and placental histopathologic examination. In summary, placental gene expression is altered in preeclampsia and we provide a comprehensive list of the differentially expressed genes. Placental gene expression is different between early- and late-onset preeclampsia, suggesting differences in pathophysiology.

Experimental validation of uterine artery volume blood flow measurement by Doppler ultrasonography in pregnant sheep

To test the hypothesis that Doppler‐derived (calculated) uterine artery volume blood flow (cQUtA) reflects accurately volume blood flow measured directly (mQUtA) in an experimental setting.

Differences in gene expression between first and third trimester human placenta : a microarray study.

Background The human placenta is a rapidly developing organ that undergoes structural and functional changes throughout the pregnancy. Our objectives were to investigate the differences in global gene expression profile, the expression of imprinted genes and the effect of smoking in first and third trimester normal human placentas. Materials and Methods Placental samples were collected from 21 women with uncomplicated pregnancies delivered at term and 16 healthy women undergoing termination of pregnancy at 9–12 weeks gestation. Placental gene expression profile was evaluated by Human Genome Survey Microarray v.2.0 (Applied Biosystems) and real-time polymerase chain reaction. Results Almost 25% of the genes spotted on the array (n = 7519) were differentially expressed between first and third trimester placentas. Genes regulating biological processes involved in cell proliferation, cell differentiation and angiogenesis were up-regulated in the first trimester; whereas cell surface receptor mediated signal transduction, G-protein mediated signalling, ion transport, neuronal activities and chemosensory perception were up-regulated in the third trimester. Pathway analysis showed that brain and placenta might share common developmental routes. Principal component analysis based on the expression of 17 imprinted genes showed a clear separation of first and third trimester placentas, indicating that epigenetic modifications occur throughout pregnancy. In smokers, a set of genes encoding oxidoreductases were differentially expressed in both trimesters. Conclusions Differences in global gene expression profile between first and third trimester human placenta reflect temporal changes in placental structure and function. Epigenetic rearrangements in the human placenta seem to occur across gestation, indicating the importance of environmental influence in the developing feto-placental unit.

Placental Gene Expression Profile in Intrauterine Growth Restriction Due to Placental Insufficiency

We evaluated global placental gene expression in intrauterine growth restriction (IUGR; n = 8) compared to normal pregnancies (n = 8) and studied possible additional effect of preeclampsia. Placental samples were collected from IUGR pregnancies due to placental insufficiency ascertained by hemodynamic studies. Four IUGR pregnancies were associated with preeclampsia. Gene expression profile was evaluated by 30k oligonucleotide microarrays. Principal component analysis (PCA) showed good separation in terms of gene expression patterns between the groups. Pathway analysis showed upregulation of inflammation mediated by chemokine and cytokine signaling pathway in the IUGR placentas. Genes involved in placental glucocorticoid metabolism were also differentially expressed. None of the known imprinted placental genes were differentially expressed. Subgroup analysis between IUGR placentas with and without preeclampsia showed few (n = 27) differentially expressed genes. In conclusion, IUGR due to placental insufficiency appears to alter placental glucocorticoid metabolism, upregulates inflammatory response in placenta, and shares common pathogenic mechanisms with severe early-onset preeclampsia.

Oxygen uptake of the human fetus at term

Objective. To measure oxygen uptake of term human fetuses and compare the values between those delivered vaginally following normal labor and those delivered by cesarean section before the onset of labor. Design. This was a prospective cross‐sectional study. Setting. University teaching hospital. Sample. Twenty healthy pregnant women at term (38–42 weeks) were included in this study. Among them, 10 were delivered by elective cesarean section and 10 had normal vaginal delivery. Methods. Umbilical vein volume blood flow was measured <24 hours before delivery. Immediately after delivery, the fetal weight was determined, and the umbilical venous and arterial blood samples were obtained. Blood gas analysis was performed and hemoglobin content was measured. Fetal oxygen uptake was calculated as a product of umbilical venous blood flow and the difference in the umbilical arterial and venous oxygen content. Results. We found that the mean oxygen uptake in human fetuses at term (median gestational age 39 weeks) to be 6.58 ml/min/kg (i.e. 0.29 mmol/min/kg). There was no significant difference in oxygen uptake between fetuses delivered following uncomplicated normal labor and those delivered by elective cesarean section before the onset of labor. Conclusion. Oxygen uptake of the appropriately grown normal human fetus at term is approximately 6.6 ml/kg/min and is not significantly affected by normal labor and delivery. Human fetuses tolerate intermittent reductions in uterine blood flow and oxygen supply associated with myometrial contractions during normal labor quite well.

Pregnancy protects against antiangiogenic and fibrogenic effects of angiotensin II in rat hearts.

Aim:  To investigate the difference between physiological and pathological cardiac remodelling induced, respectively, by pregnancy and angiotensin (Ang) II, and to test the hypothesis that pregnancy protects against Ang II effects.

Gene expression profile in cardiovascular disease and preeclampsia: A meta-analysis of the transcriptome based on raw data from human studies deposited in Gene Expression Omnibus

INTRODUCTION Cardiovascular disease (CVD) and preeclampsia (PE) share common clinical features. We aimed to identify common transcriptomic signatures involved in CVD and PE in humans. METHODS Meta-analysis of individual raw microarray data deposited in GEO, obtained from blood samples of patients with CVD versus controls and placental samples from women with PE versus healthy women with uncomplicated pregnancies. Annotation of cases versus control samples was taken directly from the microarray documentation. Genes that showed a significant differential expression in the majority of experiments were selected for subsequent analysis. Hypergeometric gene list analysis was performed using Bioconductor GOstats package. Bioinformatic analysis was performed in PANTHER. RESULTS Seven studies in CVD and 5 studies in PE were eligible for meta-analysis. A total of 181 genes were found to be differentially expressed in microarray studies investigating gene expression in blood samples obtained from patients with CVD compared to controls and 925 genes were differentially expressed between preeclamptic and healthy placentas. Among these differentially expressed genes, 22 were common between CVD and PE. DISCUSSION Bioinformatic analysis of these genes revealed oxidative stress, p-53 pathway feedback, inflammation mediated by chemokines and cytokines, interleukin signaling, B-cell activation, PDGF signaling, Wnt signaling, integrin signaling and Alzheimer disease pathways to be involved in the pathophysiology of both CVD and PE. Metabolism, development, response to stimulus, immune response and cell communication were the associated biologic processes in both conditions. Gene set enrichment analysis showed the following overlapping pathways between CVD and PE: TGF-β-signaling, apoptosis, graft-versus-host disease, allograft rejection, chemokine signaling, steroid hormone synthesis, type I and II diabetes mellitus, VEGF signaling, pathways in cancer, GNRH signaling, Huntingtons disease and Notch signaling. CONCLUSION CVD and PE share same common traits in their gene expression profile indicating common pathways in their pathophysiology.

Coronary Flow Reserve in Pregnant Rats with Increased Left Ventricular Afterload

Background Coronary flow reserve (CFR) is used as a measure of coronary endothelial function. We investigated the effect of increased afterload on CFR of pregnant and non-pregnant rats. Methods Afterload increase in Wister rats (both pregnant and non-pregnant) was achieved by the infusion of angiotensin II (Ang II) for ∼10 days or by subjecting them to transverse aortic constriction (TAC) for ∼14 days. Control groups were infused with 0.9% NaCl or had sham surgery, respectively. In pregnant rats, the experiments were performed close to term gestation. Doppler velocity waveforms of the left main coronary artery were recorded using a high resolution ultrasound imaging system (Vevo 770, VisualSonics, Canada) at baseline while the animals were anesthetized with 1.5% inhaled isoflurane, and during maximal coronary dilatation obtained by the inhalation of 3.5% of isoflurane. CFR was calculated as the ratio between the peak coronary flow velocities (CFRpeak) and the velocity-time integrals (CFRVTI) recorded at hyperemia and at baseline. Results CFR could be calculated in 60 of 75 (80%) animals. There were no differences in CFR between intervention and control groups irrespective of whether afterload was increased by Ang II or TAC. In the TAC-study CFRpeak (1.54±0.07 vs 1.85±0.17; p = 0.03) was decreased in pregnant compared to non-pregnant shams. When sham animals from both studies were pooled together both CFRpeak (1.42±0.07 vs 1.86±0.16; p = 0.005) as well as CFRVTI (1.45±0.07 vs 1.78±0.12; p = 0.03) were significantly lower in pregnant rats compared to non-pregnant. Conclusions CFR can be measured non-invasively in rats using Doppler echocardiography and high concentrations of inhaled isoflurane as a coronary vasodilator. In pregnant rats, CFR is reduced close to term. CFR is not affected by increased left ventricular afterload caused by chronic Ang II infusion or TAC.

Strategies to reduce global maternal mortality

A maternal death is a devastating event, with consequences for the family and society. Direct causes, complications that occur directly as a result of pregnancy or delivery, account for 73 percent of maternal deaths worldwide, with postpartum hemorrhage causing approximately one-third of all maternal deaths (1). Indirect causes, or pre-existing medical conditions deteriorating during pregnancy and puerperium, account for the remaining 27 percent. Typically, countries with a low maternal mortality ratio (MMR, defined as number of maternal deaths per 100 000 livebirths), have a lower proportion of direct compared to indirect causes, because their health care systems tackle direct causes of death more effectively. During the period 1990–2015, the MMR fell by 44 percent worldwide, to an estimated 216 maternal deaths per 100 000 livebirths in 2015 (2). The progress was significant, but did not reach the United Nations (UN) Millennium Development Goal of a 75 perccent reduction. Approximately 300 000 women still die each year due to conditions related to pregnancy and childbirth. The majority of maternal deaths are avoidable and occur mostly in lowand middle-income countries (1). Indeed, the 18 countries with a very high MMR (>500) are in sub-Saharan Africa, while Nigeria and India together account for one-third of all maternal deaths, due to their vast populations. The new UN Sustainable Development Goals towards ending preventable maternal deaths were released in 2015 (3). The new aim is to reduce the global MMR to less than 70 by 2030. If this is not achievable in a country, the goals are to reduce the 2010 baseline MMR by at least two-thirds and that no country should have an MMR over 140.

Obstetric and psychological characteristics of women choosing epidural analgesia during labour: A cohort study

Objectives To investigate the obstetric and psychological characteristics of women who opt to use epidural analgesia (EDA) during labour and the impact of participating in labour preparation courses on women’s decisions to use EDA. Design Longitudinal cohort study. Setting Akershus University Hospital, Norway. Population 2596 women with singleton pregnancies and intended vaginal delivery. Methods Data were collected using two self-completed questionnaires at pregnancy weeks 17 and 32. Fear of childbirth was assessed by the Wijma Delivery Expectancy Questionnaire (W-DEQ). Symptoms of anxiety were measured by the Hopkins Symptom Check List (SCL-25) and depression by the Edinburgh Postnatal Depression Scale (EPDS). Obstetric and socio-demographic information was retrieved from birth records at the maternity ward. Main outcome measure Preference for EDA was indicated by the questionnaire item “I would prefer an epidural regardless” on a 4-point scale (1 = highly agree, 4 = highly disagree) at pregnancy week 32. Results Twenty-one percent of the women (540/2596) answered that they would choose EDA as the only alternative method of analgesia during labour. Counselling for fear of childbirth [OR 3.23 (95%CI 2.12; 4.92)] and W-DEQ sum score ≥ 85 [OR 2.95 (95%CI 2.06; 4.23)] were significantly (p<0.001) associated with choice of EDA. Participation in labour preparation courses was significantly (p = 0.008) associated with a reduction of intended use of EDA during labour [OR 0.67 (95%CI 0.49; 0.90)]. Conclusion Fear of childbirth is significantly associated with women’s choice of EDA during labour. On the other hand, women that participate in labour preparation courses would rather consider other methods of analgesia during labour.