Computational fluid dynamic simulations of maternal circulation : wall shear stress in the human placenta and its biological implications

Introduction In the human placenta the maternal blood circulates in the intervillous space (IVS). The syncytiotrophoblast (STB) is in direct contact with maternal blood. The wall shear stress (WSS) exerted by the maternal blood flow on the STB has not been evaluated. Our objective was to determine the physiological WSS exerted on the surface of the STB during the third trimester of pregnancy. Material and Methods To gain insight into the shear stress levels that the STB is expected to experience in vivo, we have formulated three different computational models of varying levels of complexity that reflect different physical representations of the IVS. Computations of the flow fields in all models were performed using the CFD module of the finite element code COMSOL Multi-physics 4.4. The mean velocity of maternal blood in the IVS during the third trimester was measured in vivo with dynamic MRI (0.94 +/- 0.14 mm.s(-1)). To investigate if the in silico results are consistent with physiological observations, we studied the cytoadhesion of human parasitized (Plasmodium falciparum) erythrocytes to primary human STB cultures, in flow conditions with different WSS values. Results The WSS applied to the STB is highly heterogeneous in the IVS. The estimated average values are relatively low (0.5 +/- 0.2 to 2.3 +/- 1.1 dyn.cm(-2)). The increase of WSS from 0.15 to 5 dyn.cm(-2) was associated with a significant decrease of infected erythrocyte cytoadhesion. No cytoadhesion of infected erythrocytes was observed above 5 dyn.cm(-2) applied for one hour. Conclusion Our study provides for the first time a WSS estimation in the maternal placental circulation. In spite of high maternal blood flow rates, the average WSS applied at the surface of the chorionic villi is low (<5 dyn.cm(-2)). These results provide the basis for future physiologicallyrelevant in vitro studies of the biological effects of WSS on the STB

THU0275 SEVERE PREECLAMPSIA RELATED TO ANTIPHOSPHOLIPID SYNDROME: AN EUROPEAN STUDY OF 40 WOMEN

Background:One of the 3 features of obstetrical antiphospholipid syndrome (APS) is severe preeclampsia (PE). Its time of occurrence, the associated risk of thromboses and systemic lupus erythematosus (SLE) have not been reported yet.Objectives:We analyzed severe PE in a series of women with APS.Methods:We retrospectively collected data of female patients from 5 French internal medicine and 1 Italian rheumatology units. Inclusion criteria were: a severe PE/eclampsia(1), that occurred before 34 weeks of gestation (WG) in patients who met the APS classification criteria(2).Results:40 patients were enrolled (Table 1). Because of known APS/positive aPL/previous obstetrical complications, 23(57.5%) patients were treated during the index PE: 4 with low dose aspirin (LDA), 4 with low molecular weight heparin (LMWH), and 15 with a combination of both. 7 patients were also treated with hydroxychloroquine, 8 with corticosteroids and 3 with immunosuppressants. 17(42.5%) patients received no treatment. 24(60%) live births were observed. During a follow-up period of 3 years, 26(65%) patients had at least 1 new pregnancy, with a total of 38 pregnancies which resulted in 33(86.8%) live births. 57.5% pregnancies who resulted in live births occurred without any maternal or fetal complications. All 26 patients who had at least 1 pregnancy after index PE were treated with LDA; LMWH was given at prophylactic and therapeutic dosage in 13(50%) patients, respectively. No patient experienced 3 consecutive miscarriages.Table 1.40 APS patients with severe PEOverall features (n, %)Patients40 (100)Age at PE, (median, IQR)30.5 (27-33)PE term, WG (median, IQR)25.5 (23-29) Live births24 (60) Birth term, WG (median, IQR)25.5 (23.7-30.3) Associated SLE12 (30)Maternal complications (n, %)25 (62.5) HELLP18 (45) E6 (15) CAPS3 (7.5) Placental abruptions3 (7.5)Fetal complications (n, %)31 (77.5) IUGR18 (45) IUFD11 (2.5) Preterm delivery22 (55)Obstetrical history (n, %) Primiparous21 (52.5) Index PE before APS12 (30)Thrombosis (n, %) Thrombosis before PE index14 (35.0) Thrombosis after PE index2 (5.0)Abs at APS diagnosis (n, %) aPL triple positivity21 (52.5) IgG/IgM anti-cardiolipin34 (85.0) IgG/IgM anti-β2GPI25 (62.5) LAC33 (82.5)Legend to Table 1:PE: preeclampsia; APS: antiphospholipid syndrome; IQR: interquartile range; WG: weeks of gestation; SLE: systemic lupus erythematosus; HELLP: Hemolysis, elevated liver enzymes, low platelet; E: eclampsia; CAPS: catastrophic APS; IUGR: intrauterine growth restriction; IUFD: intrauterine fetal death; CHB: congenital atrioventricular block; aPL: antiphospholipid antibodies; LAC: lupus anticoagulant.Conclusion:Among the APS criteria, "3 consecutive miscarriages criterion" was not found. The majority of patients also experienced thrombosis and SLE before the index PE.References:[1]Diagnosis and Management of preeclampsia and eclampsia. International Journal of Gynecology &Obestetrics 2002;77:67-75.[2]Miyakis S, et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost 2006;4:295e 306.Disclosure of Interests:Maddalena Larosa: None declared, Nathalie Morel: None declared, Meriem BELHOCINE: None declared, Amelia Ruffatti: None declared, Nicolas Martin Silva: None declared, Romain Paul: None declared, Luc Mouthon: None declared, Michel DREYFUS: None declared, Jean-Charles PIETTE: None declared, Odile Souchaud-Debouverie: None declared, Catherine Deneux-Tharaux: None declared, Vassilis Tsatsaris: None declared, Emmanuelle Pannier: None declared, Gaêlle Guettrot Imbert: None declared, Véronique LE GUERN Grant/research support from: UCB for GR2 study (to our institution), Andrea Doria Consultant of: GSK, Pfizer, Abbvie, Novartis, Ely Lilly, Speakers bureau: UCB pharma, GSK, Pfizer, Janssen, Abbvie, Novartis, Ely Lilly, BMS, Nathalie Costedoat-Chalumeau Grant/research support from: UCB to my institutio

Alternate processing of Flt1 transcripts is directed by conserved cis-elements within an intronic region of FLT1 that reciprocally regulates splicing and polyadenylation

The vascular endothelial growth factor receptor, Flt1 is a transmembrane receptor co-expressed with an alternate transcript encoding a secreted form, sFlt1, that functions as a competitive inhibitor of Flt1. Despite shared transcription start sites and upstream regulatory elements, sFlt1 is in far greater excess of Flt1 in the human placenta. Phorbol myristic acid and dimethyloxalylglycine differentially stimulate sFlt1 compared to Flt1 expression in vascular endothelial cells and in cytotrophoblasts. An FLT1 minigene construct containing exon 13, 14 and the intervening region, recapitulates mRNA processing when transfected into COS-7, with chimeric intronic sFlt1 transcripts arising by intronic polyadenylation and other Flt1/sFlt1 transcripts by alternate splicing. Inclusion of exon 15 but not 14 had a modest stimulatory effect on the abundance of sFlt1. The intronic region containing the distal poly(A) signal sequences, when transferred to a heterologous minigene construct, inhibited splicing but only when cloned in sense orientation, consistent with the presence of a directional cis-element. Serial deletional and targeted mutational analysis of cis-elements within intron 13 identified intronic poly(A) signal sequences and adjacent cis-elements as the principal determinants of the relative ratio of intronic sFlt1 and spliced Flt1. We conclude that intronic signals reciprocally regulate splicing and polyadenylation and control sFlt1 expression

Differential Expression of Vegfr-2 and Its Soluble Form in Preeclampsia

Several studies have suggested that the main features of preeclampsia (PE) are consequences of endothelial dysfunction related to excess circulating anti-angiogenic factors, most notably, soluble sVEGFR-1 (also known as sFlt-1) and soluble endoglin (sEng), as well as to decreased PlGF. Recently, soluble VEGF type 2 receptor (sVEGFR-2) has emerged as a crucial regulator of lymphangiogenesis. To date, however, there is a paucity of information on the changes of VEGFR-2 that occur during the clinical onset of PE. Therefore, the aim of our study was to characterize the plasma levels of VEGFR-2 in PE patients and to perform VEGFR-2 immunolocalization in placenta.By ELISA, we observed that the VEGFR-2 plasma levels were reduced during PE compared with normal gestational age matched pregnancies, whereas the VEGFR-1 and Eng plasma levels were increased. The dramatic drop in the VEGFR-1 levels shortly after delivery confirmed its placental origin. In contrast, the plasma levels of Eng and VEGFR-2 decreased only moderately during the early postpartum period. An RT-PCR analysis showed that the relative levels of VEGFR-1, sVEGFR-1 and Eng mRNA were increased in the placentas of women with severe PE. The relative levels of VEGFR-2 mRNA as well as expressing cells, were similar in both groups. We also made the novel finding that a recently described alternatively spliced VEGFR-2 mRNA variant was present at lower relative levels in the preeclamptic placentas.Our results indicate that the plasma levels of anti-angiogenic factors, particularly VEGFR-1 and VEGFR-2, behave in different ways after delivery. The rapid decrease in plasma VEGFR-1 levels appears to be a consequence of the delivery of the placenta. The persistent circulating levels of VEGFR-2 suggest a maternal endothelial origin of this peptide. The decreased VEGFR-2 plasma levels in preeclamptic women may serve as a marker of endothelial dysfunction

Associations between clinical canine leishmaniosis and multiple vector-borne co-infections: a case-control serological study

Dogs that have clinical leishmaniosis (ClinL), caused by the parasite Leishmania infantum, are commonly co-infected with other pathogens, especially vector-borne pathogens (VBP). A recent PCR-based study found that ClinL dogs are more likely to be additionally infected with the rickettsial bacteria Ehrlichia canis. Further information on co-infections in ClinL cases with VBP, as assessed by serology, is required. The research described in this report determined if dogs with ClinL are at higher risk of exposure to VBP than healthy control dogs using a case-control serology study

Loss-of-function and missense variants in NSD2 cause decreased methylation activity and are associated with a distinct developmental phenotype

PURPOSE: Despite a few recent reports of patients harboring truncating variants in NSD2, a gene considered critical for the Wolf–Hirschhorn syndrome (WHS) phenotype, the clinical spectrum associated with NSD2 pathogenic variants remains poorly understood. METHODS: We collected a comprehensive series of 18 unpublished patients carrying heterozygous missense, elongating, or truncating NSD2 variants; compared their clinical data to the typical WHS phenotype after pooling them with ten previously described patients; and assessed the underlying molecular mechanism by structural modeling and measuring methylation activity in vitro. RESULTS: The core NSD2-associated phenotype includes mostly mild developmental delay, prenatal-onset growth retardation, low body mass index, and characteristic facial features distinct from WHS. Patients carrying missense variants were significantly taller and had more frequent behavioral/psychological issues compared with those harboring truncating variants. Structural in silico modeling suggested interference with NSD2’s folding and function for all missense variants in known structures. In vitro testing showed reduced methylation activity and failure to reconstitute H3K36me2 in NSD2 knockout cells for most missense variants. CONCLUSION: NSD2 loss-of-function variants lead to a distinct, rather mild phenotype partially overlapping with WHS. To avoid confusion for patients, NSD2 deficiency may be named Rauch–Steindl syndrome after the delineators of this phenotype

Extending the scope of pooled analyses of individual patient biomarker data from heterogeneous laboratory platforms and cohorts using merging algorithms

Background: A common challenge in medicine, exemplified in the analysis of biomarker data, is that large studies are needed for sufficient statistical power. Often, this may only be achievable by aggregating multiple cohorts. However, different studies may use disparate platforms for laboratory analysis, which can hinder merging. Methods: Using circulating placental growth factor (PIGF), a potential biomarker for hypertensive disorders of pregnancy (HDP) such as preeclampsia, as an example, we investigated how such issues can be overcome by inter-platform standardization and merging algorithms. We studied 16,462 pregnancies from 22 study cohorts. PIGF measurements (gestational age >= 20 weeks) analyzed on one of four platforms: R & Systems, Alere (R) Triage, Roche (R) Elecsys or Abbott (R) Architect, were available for 13,429 women. Two merging algorithms, using Z-Score and Multiple of Median transformations, were applied. Results: Best reference curves (BRC), based on merged, transformed PIGF measurements in uncomplicated pregnancy across six gestational age groups, were estimated. Identification of HDP by these PIGF-BRCS was compared to that of platform-specific curves. Conclusions: We demonstrate the feasibility of merging PIGF concentrations from different analytical platforms. Overall BRC identification of HDP performed at least as well as platform-specific curves. Our method can be extended to any set of biomarkers obtained from different laboratory platforms in any field. Merged biomarker data from multiple studies will improve statistical power and enlarge our understanding of the pathophysiology and management of medical syndromes. (C) 2015 International Society for the Study of Hypertension in Pregnancy. Published by Elsevier B.V. All rights reserved.Peer reviewe

Beyond oxygen: complex regulation and activity of hypoxia inducible factors in pregnancy

In the first trimester the extravillous cytotrophoblast cells occlude the uterine spiral arterioles creating a low oxygen environment early in pregnancy, which is essential for pregnancy success. Paradoxically, shallow trophoblast invasion and defective vascular remodelling of the uterine spiral arteries in the first trimester may result in impaired placental perfusion and chronic placental ischemia and hypoxia later in gestation leading to adverse pregnancy outcomes. The hypoxia inducible factors (HIFs) are key mediators of the response to low oxygen. We aimed to elucidate mechanisms of regulation of HIFs and the role these may play in the control of placental differentiation, growth and function in both normal and pathological pregnancies. The Pubmed database was consulted for identification of the most relevant published articles. Search terms used were oxygen, placenta, trophoblast, pregnancy, HIF and hypoxia. The HIFs are able to function throughout all aspects of normal and abnormal placental differentiation, growth and function; during the first trimester (physiologically low oxygen), during mid-late gestation (where there is adequate supply of blood and oxygen to the placenta) and in pathological pregnancies complicated by placental hypoxia/ischemia. During normal pregnancy HIFs may respond to complex alterations in oxygen, hormones, cytokines and growth factors to regulate placental invasion, differentiation, transport and vascularization. In the ever-changing environment created during pregnancy, the HIFs appear to act as key mediators of placental development and function and thereby are likely to be important contributors to both normal and adverse pregnancy outcomes

Role of chaos in atherosclerosis

Objective: The aim of the study is to investigate whether chaotic phenomena affect the process of atherosclerosis (ATH). Methods: Modeling the major elements in the initiation of atherosclerosis, that is to say, oxLDL, macrophages (MAC) and foam cells (FCE), a set of three first order differential equations has been developed and studied in phase-space (x,y,z). Results: The elementary equilibrium points in three dimensional phase portrait analysis, including attractors, saddles and repellors. Conclusions: Attractors indicate a stable equilibrium point, which attenuates the evolution of ATH,while the saddles and particularly the repellors correspond to an unstable dynamic system, which promotes the formation of ATH-plaques.Among other mechanisms, chaotic phenomena also seem to regulate in a particular way the ATH-process, that calls for further theoretical and experimental research. © 2006 Bentham Science Publishers Ltd

Effect of temperature increase on the distensibility of porcine thoracic aorta

The objective of the study was to investigate the temperature impact on the elasticity of porcine thoracic aorta. Under general anesthesia, 16 Landrace pigs were subjected to thoracotomy, and the descending thoracic aorta was removed and stored in normal saline. Serial sections of the vessel created cylindrical aortic specimens which were tested in a uniaxial tension device to determine the elastic properties of the aortic wall. In the control, Group A (n = 8), the aortic tissues were tested while immersed in normal saline bath of temperature TA = 37.0 ± 0.5°C, while in Group B, the temperature was TB = 40.0 ± 0.5°C. Each experiment took place only after the tissues had remained for 15 min in temperature TA or TB. For the results, the stiffness modulus of Group B showed a significant decrease (P &lt; 0.05) at medium strain level deformation (e = 1, SB1 = 114 ± 8 Pa) as well as at high strain level deformation (e = 2, SB1 = 1182 ± 48 Pa) in comparison with the control, Group A (e = 1, SA1 = 147 ± 15 Pa; e = 2, SA1 = 1479 ± 64 Pa). It is concluded that temperature increase facilitates, in vitro, the expansion of descending thoracic aorta. We assume that thermal treatment may be another means against the stiffening of aorta, which calls for further research. © 2005 International Center for Artificial Organs and Transplantation