π-electron S = ½ quantum spin-liquid state in an ionic polyaromatic hydrocarbon.

Molecular solids with cooperative electronic properties based purely on π electrons from carbon atoms offer a fertile ground in the search for exotic states of matter, including unconventional superconductivity and quantum magnetism. The field was ignited by reports of high-temperature superconductivity in materials obtained by the reaction of alkali metals with polyaromatic hydrocarbons, such as phenanthrene and picene, but the composition and structure of any compound in this family remained unknown. Here we isolate the binary caesium salts of phenanthrene, Cs(C14H10) and Cs2(C14H10), to show that they are multiorbital strongly correlated Mott insulators. Whereas Cs2(C14H10) is diamagnetic because of orbital polarization, Cs(C14H10) is a Heisenberg antiferromagnet with a gapped spin-liquid state that emerges from the coupled highly frustrated Δ-chain magnetic topology of the alternating-exchange spiral tubes of S = ½ (C14H10)•- radical anions. The absence of long-range magnetic order down to 1.8 K (T/J ≈ 0.02; J is the dominant exchange constant) renders the compound an excellent candidate for a spin-½ quantum-spin liquid (QSL) that arises purely from carbon π electrons.

Genetic variants in pre-eclampsia: a meta-analysis.

BACKGROUND Pre-eclampsia has a clear familial component, suggesting that the condition may be partly attributable to genetic susceptibility. The search for susceptibility genes has led to a drastic increase in the number of published studies associating genetic factors with pre-eclampsia. However, attempts to replicate these findings have yielded inconsistent results. This meta-analysis assessed the pooled effect of each genetic variant that is reproducibly associated with pre-eclampsia. METHODS Studies that assessed the association between genes and pre-eclampsia were searched in PubMed, Embase and Web of Science. We selected all genetic variants that were significantly associated with pre-eclampsia in an initial study and were subsequently independently reproduced in at least one additional study. All studies that assessed these reproduced variants were then included. The association between genetic variants and pre-eclampsia was calculated at the allele level, and the main measure of effect was a pooled odds ratio in a random-effects model. RESULTS The literature search yielded 2965 articles, of which 542 investigated genetic associations in pre-eclampsia. We identified 22 replicated genetic variants, of which 7 remained significantly associated with pre-eclampsia following meta-analysis. These variants were in or near the following genes: ACE, CTLA4, F2, FV, LPL and SERPINE1. CONCLUSIONS This meta-analysis identified seven genetic variants associated with pre-eclampsia. Importantly, many of these variants are also risk factors for developing cardiovascular disease, revealing that pre-eclampsia and cardiovascular disease have shared genetic risk factors. The contribution of the identified genetic variants in the pathogenesis of pre-eclampsia should be the focus of future studies.

OS050. Genetic variants in pre-eclampsia: a meta-analysis.

INTRODUCTION: Preeclampsia has a clear familial component, suggesting that the syndrome may be partly attributable to genetic susceptibility. The search for susceptibility genes has lead to a massive increase in the number of published studies involving genetic associations in preeclampsia. However, attempts to replicate these findings have yielded inconsistent results. This meta-analysis aims to assess the pooled effect of each genetic variant that is reproducibly associated with preeclampsia. OBJECTIVES: To create an overview of the genetic variants that are reproducibly associated with preeclampsia. METHODS: Studies assessing the association between genes and preeclampsia were searched in PubMed, EMBASE and Web of Science. We selected all genetic variants that were significantly associated with preeclampsia in an initial study and then independently reproduced in at least one additional study. Subsequently, all studies assessing these reproduced variants were included. The association between these variants and preeclampsia was calculated at the allele level and the main measure of effect was a pooled odds ratio. RESULTS: The literature search resulted in 2965 citations, of which 542 were genetic association studies investigating preeclampsia. We identified 23 replicated genetic variants, of which 8 remained significantly associated with preeclampsia in a random-effects meta-analysis. These variants were in or near the following genes: ACE,AGT,CTLA4,F2,FV (two variants),LPL and SERPINE1. CONCLUSION: This meta-analysis found 8 genetic variants associated with preeclampsia. Most of these variants are in the renin-angiotensin and the coagulation system. Importantly, many of the variants that were associated with preeclampsia are known to be risk factors for the development of cardiovascular disease, indicating that preeclampsia and cardiovascular disease have shared genetic risk factors. The relative contribution and relevance of the identified genes in the pathogenesis of preeclampsia should be the focus of future studies.

Electronic band structure of tetracene-TCNQ and perylene-TCNQ compounds.

The relationship between the crystal structures, band structures, and electronic properties of acene-TCNQ complexes has been investigated. We focus on the newly synthesized crystals of the charge-transfer salt tetracene-TCNQ and similar to it perylene-TCNQ, potentially interesting for realization of ambipolar transport. The band structures were calculated from first principles using density-functional theory (DFT). Despite the similarity in the crystal structures of the acene-TCNQ complexes studied here, the band structures are very different. Hole and electron transport properties are predicted to be equally good in perylene-TCNQ, in contrast to the tetracene-TCNQ, which has good transport properties for electrons only. The estimated degree of charge transfer for tetracene-TCNQ is 0.13e and for perylene-TCNQ 0.46e.

Hemodynamic effects of iodixanol and iohexol during ventriculography in patients with compromised left ventricular function.

A crossover study was performed to compare the hemodynamic effects of the iso-osmolar contrast agent iodixanol (Visipaque) 320 mg I/ml to those of the low-osmolar iohexol (Omnipaque) 350 mg I/ml. The main hypothesis was that iodixanol and iohexol would affect left ventricular end-diastolic pressure (LVEDP) to different degrees. In 48 patients with reduced cardiac function (mean ejection fraction 33. 4%), one ventricular injection was performed with each contrast medium. Ventricular, aortic and right atrial pressures and heart rate were measured continuously. Cardiac output (using Fick's principle) and systemic vascular resistance were calculated. LVEDP increased with both agents, but significantly less after iodixanol than after iohexol (P < 0.01), also in subgroups of patients in whom baseline LVEDP was severely increased and in whom 3-vessel disease was present. Immediate changes in variables reflecting vasodilatation were similar with both agents. In conclusion, both contrast agents influenced hemodynamics during ventriculography, but iodixanol had significantly less influence on LVEDP than did iohexol.

Hemodynamic effects of dynamic exercise in children and adolescents with moderate-to-small ventricular septal defects.

We studied the hemodynamic effects of dynamic exercise during cardiac catheterization in 35 children and adolescents with small-to-moderate ventricular septal defects. Eighteen of them exercised at 25% and 50% of their maximum workload and 17 exercised at 60%. There was no significant difference between the two groups with respect to age and body mass, height, and surface area. The changes evoked by exercise showed the same pattern at the different workloads, although they were more marked at the higher than at the lower percentage of maximum workload. During exercise the pulmonary vascular resistance did not change, in contrast to the systemic vascular resistance, which decreased. The pulmonary and systemic blood flows both increased, while the left-to-right shunt flow did not change, which led to a decrease of the left-to-right shunt fraction. As the heart rate increased and the shunt flow did not change, the shunt volume per beat decreased during exercise. We conclude that in patients with small-to-moderate ventricular septal defects the hemodynamic effects of dynamic exercise are favorable because the normal rise in systemic blood flow occurs without a corresponding increase in left-to-right shunt flow. Consequently, children and adolescents with such defects should not be restricted in their dynamic exercise activities.