Buoyant crystals halt the cooling of white dwarf stars.

White dwarfs are stellar remnants devoid of a nuclear energy source, gradually cooling over billions of years and eventually freezing into a solid state from the inside out. Recently, it was discovered that a population of freezing white dwarfs maintains a constant luminosity for a duration comparable with the age of the universe, signalling the presence of a powerful, yet unknown, energy source that inhibits the cooling. For certain core compositions, the freezing process is predicted to trigger a solid-liquid distillation mechanism, owing to the solid phase being depleted in heavy impurities.

Perinatal morbidity among women with a previous caesarean delivery (PRISMA trial): a cluster-randomised trial.

Background: Women with a previous caesarean delivery face a difficult choice in their next pregnancy: planning another caesarean or attempting vaginal delivery, both of which are associated with potential maternal and perinatal complications. This trial aimed to assess whether a multifaceted intervention, which promoted person-centred decision making and best practices, would reduce the risk of major perinatal morbidity among women with one previous caesarean delivery.

Methods: We conducted an open, multicentre, cluster-randomised, controlled trial of a multifaceted 2-year intervention in 40 hospitals in Quebec among women with one previous caesarean delivery, in which hospitals were the units of randomisation and women the units of analysis.

Understanding the role of flux, pressure and temperature on polymorphism in ThBO.

A novel polymorph of ThBO, denoted as β-ThBO, was synthesised under high-temperature high-pressure (HT/HP) conditions. single crystal X-ray diffraction measurements, β-ThBO was found to form a three-dimensional (3D) framework structure where thorium atoms are ten-fold oxygen coordinated forming tetra-capped trigonal prisms. The only other known polymorph of ThBO, denoted α, synthesised herein using a known borax, BO-NaBO, high temperature solid method, was found to transform to the β polymorph when exposed to conditions of 4 GPa and ∼900 °C.

Direct evaluation of the phase diagrams of dense multicomponent plasmas by integration of the Clapeyron equations.

Accurate phase diagrams of multicomponent plasmas are required for the modeling of dense stellar plasmas, such as those found in the cores of white dwarf stars and the crusts of neutron stars. Those phase diagrams have been computed using a variety of standard techniques, which suffer from physical and computational limitations. Here we present an efficient and accurate method that overcomes the drawbacks of previously used approaches.

A giant planet candidate transiting a white dwarf.

Astronomers have discovered thousands of planets outside the Solar System, most of which orbit stars that will eventually evolve into red giants and then into white dwarfs. During the red giant phase, any close-orbiting planets will be engulfed by the star, but more distant planets can survive this phase and remain in orbit around the white dwarf. Some white dwarfs show evidence for rocky material floating in their atmospheres, in warm debris disks or orbiting very closely, which has been interpreted as the debris of rocky planets that were scattered inwards and tidally disrupted.

Impact of Audits and Multifaceted Intervention on Vaginal Birth After Caesarean: Secondary Analysis of the QUARISMA Trial.

Objectives: This study estimated the effect that a multifaceted intervention aiming to improve the quality of obstetrical care and reduce Caesarean section (CS) had on the rate of vaginal birth after Caesarean (VBAC).

Methods: This is a secondary analysis of the cluster randomized controlled trial Quality of Care, Obstetrics Risk Management, and Mode of Delivery involving (1) audits regarding the indications for CS, (2) provision of feedback to health professionals, and (3) implementation of best practices to reduce CS rates in Quebec. The impact of intervention on VBAC, trial of labour (TOL), and maternal and neonatal morbidity was reported using adjusted odds ratios (ORs) with 95% confidence intervals (CIs).

Reporting Caesarean Delivery in Quebec Using the Robson Classification System.

Objective: The increasing rates of Caesarean sections throughout the world is preoccupant, and a good understanding of which groups of women contribute the most to the CS rate represents an important question in public health. Therefore, we sought to report the CS rate according to the Robson's classification system in the Quebec population.

Method: We performed a secondary analysis of the QUARISMA database, including all deliveries after 24 weeks' gestation from 32 maternity wards in the province of Quebec between 2008 and 2011 (n = 184 952 deliveries).

Impact of tamsulosin and nifedipine on contractility of pregnant rat ureters in vitro.

Objectives: To evaluate the in vitro effect of tamsulosin and nifedipine on the contractility of pregnant rat ureters and to perform quantitative analysis of the pharmacological effects. Medical expulsive therapy (MET) is commonly used to treat urolithiasis. However, this treatment is seldom used in pregnant women since no studies support this practice.

"That was intense!" Spirituality during childbirth: a mixed-method comparative study of mothers' and fathers' experiences in a public hospital.

Background: While spirituality is well described in end-of-life care literature, research on its place in the delivery room remains largely limited to mother-oriented qualitative studies focusing on life-threatening situations (e.g., high-risk pregnancies).

Antenatal montelukast treatment reduces uterine activity associated with inflammation in a pregnant rat model.

Objective: The potency of acute montelukast treatment, a leukotriene receptor antagonist, has been demonstrated as tocolytic on in vitro myometrial contractility. This study assessed the ability of a 48h montelukast treatment to modify in vitro contractions under inflammatory conditions in a pregnant rat model.

Study Design: Pregnant Sprague-Dawley rats were injected intraperitoneally (gestational days 20-22) with lipopolysaccharides (LPS) 200μg/kg (4 treatments at 12h intervals) alone or combined with montelukast 10mg/kg/day or a saline solution for a 48h period.

Neuroprotective effects of antenatal magnesium sulfate under inflammatory conditions in a Sprague-Dawley pregnant rat model.

Objective: Antenatal magnesium sulfate (MgSO) is recommended for fetal neuroprotection. The aim of this animal study was to assess the neuroprotective effect of in utero exposure to MgSO, under inflammatory conditions.

Methods: Timed pregnant Sprague-Dawley (SD) rats (n = 29) received four intra-peritoneal (IP) injections of lipopolysaccharides (LPS; 200 μg/kg), combined with increasing concentrations of MgSO (25, 50 or 100 mg/kg, n = 19) or saline solution (SS; n = 10).

Functional Studies of DNA-Protein Interactions Using FRET Techniques.

Protein-DNA interactions underpin life and play key roles in all cellular processes and functions including DNA transcription, packaging, replication, and repair. Identifying and examining the nature of these interactions is therefore a crucial prerequisite to understand the molecular basis of how these fundamental processes take place. The application of fluorescence techniques and in particular fluorescence resonance energy transfer (FRET) to provide structural and kinetic information has experienced a stunning growth during the past decade.

Levothyroxine treatment generates an abnormal uterine contractility patterns in an animal model.

Objective: Abnormal uterine contraction patterns were recently demonstrated in uterine strips from pregnant women treated with Levothyroxine (T4). These abnormalities were correlated with an increased risk of C-section delivery and associated surgical complications. To date, no study has investigated whether uterine contractility is modified by hypothyroidism or T4 treatment.

[Factors associated with breastfeeding continuation in young Canadian mothers].

Objectives: Breastfeeding continuation rates are lower among young mothers, while few studies have specifically focused on this population. This study describes the factors related to continued breastfeeding beyond two months among young Canadian mothers.

Methods: A descriptive and correlational design was used to identify and quantify the impact offactors affecting continued breast-feeding beyond two months.

Effect of endometrial ablation on premenstrual symptoms.

Study Objective: To evaluate the effect of endometrial ablation on 6 premenstrual symptoms for up to 1 year after treatment.

Design: Prospective cohort of 59 women awaiting endometrial ablation (Canadian Task Force classification II-2).

Setting: University tertiary care hospital.

Leukotriene receptor antagonist as a novel tocolytic in an in vitro model of human uterine contractility.

Objective: This study analyzed the ability of montelukast, a cysteinyl-leukotrienes receptor antagonist and anti-inflammatory agent, to produce a consistent tocolytic effect alone or in combination with nifedipine, a calcium (Ca(2+)) channel blocker currently used in clinical practice.

Study Design: Uterine biopsies were obtained from consenting women undergoing elective cesarean sections at term (n=20). Myometrial microsomal fractions were analyzed by immunoblotting to quantify relative cysteinyl leukotrienes receptor 1 (CysLTR1) levels.

Maternal and paternal satisfaction in the delivery room: a cross-sectional comparative study.

Objectives: Maternal satisfaction during the birthing process has been well documented, whereas little is known about the fathers' birth experiences. Our objective was to evaluate and compare the birth satisfaction of mothers and fathers.

Design: Comparative cross-sectional study.

Chronic levothyroxine and acute T3 treatments enhance the amplitude and time course of uterine contractions in human.

This study compares the functional consequences of levothyroxine (T4) treatment during pregnancy as well as the acute affects of triiodothyronine (T3) on spontaneous uterine contractile activities observed in vitro. Uterine biopsies were obtained from consenting women undergoing elective caesarean at term (n = 28). Spontaneous contractile activities from T4-treated pregnant women (n = 8) were compared with control patients (n = 20) by isometric tension measurements.

Constitutive regulatory activity of an evolutionarily excluded riboswitch variant.

The exquisite specificity of the adenine-responsive riboswitch toward its cognate metabolite has been shown to arise from the formation of a Watson-Crick interaction between the adenine ligand and residue U65. A recent crystal structure of a U65C adenine aptamer variant has provided a rationale for the phylogenetic conservation observed at position 39 for purine aptamers. The G39-C65 variant adopts a compact ligand-free structure in which G39 is accommodated by the ligand binding site and is base-paired to the cytosine at position 65.

Molecular insights into the ligand-controlled organization of the SAM-I riboswitch.

S-adenosylmethionine (SAM) riboswitches are widespread in bacteria, and up to five different SAM riboswitch families have been reported, highlighting the relevance of SAM regulation. On the basis of crystallographic and biochemical data, it has been postulated, but never demonstrated, that ligand recognition by SAM riboswitches involves key conformational changes in the RNA architecture. We show here that the aptamer follows a two-step hierarchical folding selectively induced by metal ions and ligand binding, each of them leading to the formation of one of the two helical stacks observed in the crystal structure.

Comparative study between transcriptionally- and translationally-acting adenine riboswitches reveals key differences in riboswitch regulatory mechanisms.

Many bacterial mRNAs are regulated at the transcriptional or translational level by ligand-binding elements called riboswitches. Although they both bind adenine, the adenine riboswitches of Bacillus subtilis and Vibrio vulnificus differ by controlling transcription and translation, respectively. Here, we demonstrate that, beyond the obvious difference in transcriptional and translational modulation, both adenine riboswitches exhibit different ligand binding properties and appear to operate under different regulation regimes (kinetic versus thermodynamic).

Folding of the lysine riboswitch: importance of peripheral elements for transcriptional regulation.

The Bacillus subtilis lysC lysine riboswitch modulates its own gene expression upon lysine binding through a transcription attenuation mechanism. The riboswitch aptamer is organized around a single five-way junction that provides the scaffold for two long-range tertiary interactions (loop L2-loop L3 and helix P2-loop L4)--all of this for the creation of a specific lysine binding site. We have determined that the interaction P2-L4 is particularly important for the organization of the ligand-binding site and for the riboswitch transcription attenuation control.

Functional studies of DNA-protein interactions using FRET techniques.

Protein-DNA interactions underpin life and play key roles in all cellular processes and functions including DNA transcription, packaging, replication, and repair. Identifying and examining the nature of these interactions is therefore a crucial prerequisite to understand the molecular basis of how these fundamental processes take place. The application of fluorescence techniques and in particular fluorescence resonance energy transfer (FRET) to provide structural and kinetic information has experienced a stunning growth during the past decade.

Riboswitches: ancient and promising genetic regulators.

BAIT AND SWITCH: Metabolite-sensing riboswitches make use of RNA structural modulation to regulate gene expression, as illustrated in the scheme, in response to subtle changes in metabolite concentrations. This review describes the current knowledge about naturally occurring riboswitches and their growing potential as antibacterial cellular targets and as molecular biosensors. Newly discovered metabolite-sensing riboswitches have revealed that cellular processes extensively make use of RNA structural modulation to regulate gene expression in response to subtle changes in metabolite concentrations.

A loop loop interaction and a K-turn motif located in the lysine aptamer domain are important for the riboswitch gene regulation control.

The lysine riboswitch is associated to the lysC gene in Bacillus subtilis, and the binding of lysine modulates the RNA structure to allow the formation of an intrinsic terminator presumably involved in transcription attenuation. The complex secondary structure of the lysine riboswitch aptamer is organized around a five-way junction that undergoes structural changes upon ligand binding. Using single-round transcription assays, we show that a loop-loop interaction is important for lysine-induced termination of transcription.