Role of pressure on electronic, magnetic and structural properties at iron's Curie temperature: a DFT + DMFT study

We use the combination of density functional theory and dynamical mean-field theory to compute the Curie temperature of the iron body-centered cubicαphase and probe its pressure dependence. Our calculations reveal thatTCshows a decrease which is very weak over a domain of pressures that is much larger than the stability domain of theαphase. This is consistent with the experimental results. We highlight the importance of the Hund's couplingJnot only on the electronic and magnetic properties but also on the structural properties. Lastly, we analyze the electronic and magnetic properties under pressure and discuss the evolution of magnetic moments in both phases in relation to the change of Curie temperature.

Single-chain magnet behavior in a finite linear hexanuclear molecule

The careful monitoring of crystallization conditions of a mixture made of a TbIII building block and a substituted nitronyl-nitroxide that typically provides infinite coordination polymers (chains), affords a remarkably stable linear hexanuclear molecule made of six TbIII ions and five NIT radicals. The hexanuclear units are double-bridged by water molecules but ab initio calculations demonstrate that this bridge is inefficient in mediating any magnetic interaction other than a small dipolar antiferromagnetic coupling. Surprisingly the hexanuclears, despite being finite molecules, show a single-chain magnet (SCM) behavior. This results in a magnetic hysteresis at low temperature whose coercive field is almost doubled when compared to the chains. We thus demonstrate that finite linear molecules can display SCM magnetic relaxation, which is a strong asset for molecular data storage purposes because 1D magnetic relaxation is more robust than the relaxation mechanisms observed in single-molecule magnets (SMMs) where under-barrier magnetic relaxation can operate.

PARE0016 MINDFULNESS-BASED STRESS REDUCTION TO IMPROVE DEPRESSIVE SYMPTOMS AND RHEUMATOID ARTHRITIS-RELATED CLINICAL OUTCOMES: RESULTS FROM A FEASIBILITY AND ACCEPTABILITY TRIAL

Background:

Despite available highly effective pharmacological treatments, up to 30% of current rheumatoid arthritis (RA) patients remain in quasi-remission, where inflammation is controlled but patients still report unacceptable levels of negative impact of RA (high Patient Global Assessment (PGA) on a 0-10 visual analog scale). PGA levels correlated with depressive symptoms assessed by Center for Epidemiologic Studies- Depression (CES-D) scores. Mindfulness-Based Stress Reduction (MBSR) is relatively inexpensive and reduces both anxiety and depression in several conditions.

Objectives:

To complete a feasibility and acceptability study paving the way for a randomized controlled trial (RCT) of MBSR to improve depressive symptoms and clinical outcomes in RA patients in quasi-remission.

Methods:

A standardized 8-week MBSR program in adults with controlled inflammatory disease (stable SJC ≤ 2/66 and normal CRP; stable treatments) but high CES-D scores (2 groups), high CES-D or anxiety scores (1 group), or PGA higher than Physician Evaluation of Disease Activity (EVA) by ≥2 (1 group). Feasibility was documented using process indicators. Outcomes were measured at baseline and 6 months after the end of MBSR. Disease activity scores (SDAI) and questionnaires on depressive symptoms (CES-D), HAQ, sleep (VAS), fatigue and pain (SF-36), anxiety (GAD-7), PGA were collected. Qualitative interviews based on a theoretical framework of acceptability were conducted following the post-MBSR evaluation.

Results:

We report on the first 21 patients (mean age 59, 91% females) having completed their 6-month follow up evaluation. Factors leading to higher recruitment rates were 1) using pragmatic scores to identify eligible patients (e.g. EVA and PGA), 2) no formal clinical evaluation of mental health and no emphasis on depression in the recruitment material.

MBSR had a highly significant positive impact on depressive symptoms (p=0.003) and anxiety (p=0.025) (Figure), and positive impact on quality of sleep and HAQ. No change in SDAI or joint counts was noted.

During a qualitative interview of 13 participants, most reported that MBSR helped them control their reactions to daily stressful situations. Perceptions were almost uniformly positive towards MBSR, and most appeared to have integrated some part of it in their daily life. No side effects were reported.

Conclusion:

Although recruitment was challenging, a MBSR trial in RA patients in quasi-remission was found acceptable and feasible. Positive impacts on mood and on clinical outcomes were observed. Anxiety and depression scores appear the most sensitive to change and are recommended as the primary outcome for an eventual RCT. MBSR added to conventional treatments might help empower RA patients towards self-management.

Acknowledgments:

Grant support from Canadian Initiative for Outcomes in Rheumatology cAre (CIORA)

Disclosure of Interests:

Marie-Claude Beaulieu: None declared, Isabelle Gaboury: None declared, Nathalie Carrier: None declared, Patricia Dobkin: None declared, France Gervais: None declared, Françoise Gendron: None declared, Pasquale Roberge: None declared, Pierre Dagenais: None declared, Sophie Roux: None declared, Gilles Boire Grant/research support from: Merck Canada (Registry of biologices, Improvement of comorbidity surveillance)

Amgen Canada (CATCH, clinical nurse)

Abbvie (CATCH, clinical nurse)

Pfizer (CATCH, Registry of biologics, Clinical nurse)

Hoffman-LaRoche (CATCH)

UCB Canada (CATCH, Clinical nurse)

BMS (CATCH, Clinical nurse, Observational Study Protocol IM101664. SEROPOSITIVITY IN A LARGE CANADIAN OBSERVATIONAL COHORT)

Janssen (CATCH)

Celgene (Clinical nurse)

Eli Lilly (Registry of biologics, Clinical nurse), Consultant of: Eli Lilly, Janssen, Novartis, Pfizer, Speakers bureau: Merck, BMS, Pfizer

A75 ON THE TRAIL OF ALTERNATIVE LIGANDS AND SIGNALING PATHWAYS FOR LGR5

Background

Leucine-rich G protein coupled receptor-5 (LGR5) is a GPCR originally identified as a marker for intestinal stem cells but is now associated to stemness in numerous other tissues. R-spondins (RSPO) are the only reported ligands of LGR5, which upon receptor binding, potentiates the canonical Wnt/b-catenin pathway. Surprisingly, despite the presence of classical GPCR features such as conserved DRY and NPXXY motifs RSPO binding to LGR5 does not induce classical GPCR behaviors such as coupling to heterotrimeric G-proteins or engagement of b-arrestins. For this reason, LGR5 is still considered to be an orphan receptor.

Aims

Aberrant expression of LGR5 is a common feature of many cancers, including gastrointestinal cancers, but it is still unclear why LGR5 is pro-tumorigenic in some cancers, while anti-tumorigenic in others. One potential explanation is that LGR5 does not only signals through the Wnt/b-catenin pathway, but also to alternative pathways. Thus, the goals of this study were 1), to elucidate LGR5 signaling networks and 2), to identify new LGR5 ligands and activity modulators. We suggested that the intestinal lumen content could be a source of bioactive molecules that could act as alternative LGR5 ligands

Methods

All experiments were performed on HEK293 cells expressing recombinant LGR5 (HEK293/LGR5) and compared to control cells expressing empty vector. Characterization of LGR5 signaling network was initiated with LC MS/MS spectrometric analyses using cells stimulated with Wnt3a and RSPO1. To identify new LGR5 modulators, commercially available bacteria-derived metabolites (BDM) were tested on HEK293/LGR5 cells stimulated with Wnt3a and RSPO1 and assessed using the TOP-Flash luciferase system. Finally, a mouse intestinal lumen extract (ILE) was investigated in whole-cell impedance assay to detect if it contained native BDM or potential host-derived LGR5 ligands.

Results

Mass spectrometric analyses revealed distinct protein expression and phosphorylation profiles in HEK293/LGR5 cells stimulated with Wnt3a and RSPO1. The TOP/Flash luciferase assays showed that the flavonoid derivative 3,4-dihydroxyphenylacetic acid (DOPAC) and lipopolysaccharide (LPS) acted as negative regulators of LGR5, while butyrate had no effect. Interestingly, stimulation of HEK293/LGR5 with ILE induced a Gαq-like response in the impedance assay, while control cells did not respond.

Conclusions

Stimulation of LGR5 with Wnt and RSPO triggered a complex signaling network. In agreement with our hypothesis, some BDM such as DOPAC and LPS were indeed activity modulators of LGR5. Moreover, a still unidentified compound present in the ILE triggered a selective GPCR-like response in HEK293/LGR5 cells. Future works aim at identifying this putative LGR5 ligand(s) and establish the LGR5 interactome using proximity labeling and mass spectrometry.

Funding Agencies

NSERC, Université de Sherbrooke, FRQS

Hysteresis Photomodulation via Single-Crystal-to-Single-Crystal Isomerization of a Photochromic Chain of Dysprosium Single-Molecule Magnets

A one-dimensional coordination solid 1_c is synthesized by reaction of a bispyridyl dithienylethene (DTE) photochromic unit with the highly anisotropic dysprosium-based single-molecule magnet [Dy(Tp^py)F(pyridine)₂]PF₆. Slow magnetic relaxation characteristics are retained in the chain compound 1_c, and photoisomerization of the bridging DTE ligand induces a single-crystal-to-single-crystal transformation that can be monitored using photocrystallography. Notably, the resulting chain compound 1_o exhibits faster low-temperature relaxation than that of 1_c, which is apparent in magnetic hysteresis data collected for both compounds as high as 4 K. Ab initio calculations suggest that this photomodulation of the magnetic relaxation behavior is due to crystal packing changes rather than changes to the crystal field splitting upon ligand isomerization.

A supramolecular chain of dimeric Dy single molecule magnets decorated with azobenzene ligands

Dy^III dimers decorated with photo-isomerizable azobenzene ligands behave as single-molecule magnets and self-organize into a supramolecular chain. Ab initio calculations, magnetic and optical properties are reported.

Set-up and routine use of a database of 10,555 genotyped blood donors to facilitate the screening of compatible blood components for alloimmunized patients

BACKGROUND AND OBJECTIVES

Large-scale genotyping of blood donors for red blood cell and platelet antigens has been predicted to replace phenotyping assays in the screening of compatible blood components for alloimmunized patients. Although several genotyping platforms have been described, novel procedures and processes are needed to perform genotyping efficiently and to maximize its benefits for blood banks.

MATERIALS AND METHODS

Here we describe the processes and procedures developed to introduce large-scale genotyping in our routine operations.

RESULTS

Preliminary cost-benefit analysis indicated that genotyping must target frequent blood donors (> 3 donations/year) to be efficiently used. A custom-designed computer application was developed to manage the whole project. It selects frequent donors among recent donations, prints coded labels to identify blood samples sent to the external genotyping laboratory, and stores genotyping results. It can search for donors compatible for any combination of the 22 genotyped antigens as well as consult the current inventory for the presence of the corresponding blood components. The phenotype of recovered components is confirmed by standard serology techniques prior to shipment to hospitals.

CONCLUSION

Since October 2007, 10 555 blood donors have been genotyped. The database is used on a regular basis to find compatible blood components with a genotype-phenotype concordance of 99.6%.

FTIR features of lithium-iron phosphates as electrode materials for rechargeable lithium batteries

The essential structural features of lithium-metal phosphates (LMP) have been studied using FTIR spectroscopy which is a sensitive tool to probe the local environment in the solid materials. Various LMP materials where M is iron have been investigated including phospho-olivine LiFePO(4), diphosphate LiFeP(2)O(7), Nasicon-type phosphate Li(3)Fe(2)(PO(4))(3) and dihydrate FePO(4).2H(2)O. Vitreous and amorphous materials are also considered. Analysis of internal and external modes of vibration allows to distinguish between the different phases and the type of cationic environment in the framework. Results corroborate the contribution of the main factors which are responsible for the complexity of the spectra, i.e. departure from ideal symmetry, interactions between polyhedra, bridging atoms and lattice distortion.

A five-year experience with second-trimester induced abortions: no increase in complication rate as compared to the first trimester

OBJECTIVE

Our purpose was to compare the complication rate of first-trimester suction curettage with that of second-trimester dilation-and-evacuation abortions in the same clinical setting.

STUDY DESIGN

Retrospective analysis (chart review) of the 3772 induced abortions performed between 1986 and 1990 at the Family Planning Clinic of the Centre Hospitalier Universitaire de Sherbrooke, Quebec, Canada.

RESULTS

Among the 3355 cases with known follow-up (89%), the complication rate was 5.1% for the 2908 suction curettages at < 15 weeks' gestation compared with 2.9% for the 447 dilation-and-evacuation procedures at 15 to 20 weeks' gestation. Serious complications were few and not increased among patients undergoing dilation and evacuation.

CONCLUSION

A careful approach to second-trimester dilation-and-evacuation procedures can make them comparatively as safe as suction curettages, contrary to common belief derived from large surveys done in the late 1970s.

"Burns" occurring during lengthy surgical procedures

Accidental burns or burn-like injuries continue to occur during lengthy surgical procedures. Many remain unexplained as to the cause. The threat of litigation suppresses discussion of the incidence of injuries of this type -- which are not uncommon. The same threat appears to have suppressed wider discussion of potential solutions. Many of these burn-like injuries are not burns but pressure sores, and as such are preventable. Strategies for reducing the numbers of injuries of this type are discussed.