Pauling Entropy, Metastability, and Equilibrium in Dy_{2}Ti_{2}O_{7} Spin Ice

Determining the fate of the Pauling entropy in the classical spin ice material Dy_{2}Ti_{2}O_{7} with respect to the third law of thermodynamics has become an important test case for understanding the existence and stability of ice-rule states in general. The standard model of spin ice-the dipolar spin ice model-predicts an ordering transition at T≈0.15  K, but recent experiments by Pomaranski et al. suggest an entropy recovery over long timescales at temperatures as high as 0.5 K, much too high to be compatible with the theory. Using neutron scattering and specific heat measurements at low temperatures and with long timescales (0.35  K/10^{6}  s and 0.5  K/10^{5}  s, respectively) on several isotopically enriched samples, we find no evidence of a reduction of ice-rule correlations or spin entropy. High-resolution simulations of the neutron structure factor show that the spin correlations remain well described by the dipolar spin ice model at all temperatures. Furthermore, by careful consideration of hyperfine contributions, we conclude that the original entropy measurements of Ramirez et al. are, after all, essentially correct: The short-time relaxation method used in that study gives a reasonably accurate estimate of the equilibrium spin ice entropy due to a cancellation of contributions.

Bone Marrow Stromal Cells Promote Innervation of Bioengineered Teeth

Transplantation of bone marrow mesenchymal stem cells (BMDCs) into a denervated side of the spinal cord was reported to be a useful option for axonal regeneration. The innervation of teeth is essential for their function and protection but does not occur spontaneously after injury. Cultured reassociations between dissociated embryonic dental mesenchymal and epithelial cells and implantation lead to a vascularized tooth organ regeneration. However, when reassociations were coimplanted with a trigeminal ganglion (TG), innervation did not occur. On the other hand, reassociations between mixed embryonic dental mesenchymal cells and bone marrow-derived cells isolated from green fluorescent protein (GFP) transgenic mice (BMDCs-GFP) (50/50) with an intact and competent dental epithelium (ED14) were innervated. In the present study, we verified the stemness of isolated BMDCs, confirmed their potential role in the innervation of bioengineered teeth, and analyzed the mechanisms by which this innervation can occur. For that purpose, reassociations between mixed embryonic dental mesenchymal cells and BMDCs-GFP with an intact and competent dental epithelium were cultured and coimplanted subcutaneously with a TG for 2 wk in ICR mice. Axons entered the dental pulp and reached the odontoblast layer. BMDCs-GFP were detected at the base of the tooth, with some being present in the pulp associated with the axons. Thus, while having a very limited contribution in tooth formation, they promoted the innervation of the bioengineered teeth. Using quantitative reverse transcription polymerase chain reaction and immunostainings, BMDCs were shown to promote innervation by 2 mechanisms: 1) via immunomodulation by reducing the number of T lymphocytes (CD3+, CD25+) in the implants and 2) by expressing neurotrophic factors such as NGF, BDNF, and NT3 for axonal growth. This strategy using autologous mesenchymal cells coming from bone marrow could be used to innervate bioengineered teeth without treatment with an immunosuppressor such as cyclosporine A (CsA), thus avoiding multiple side effects.

Heterozygosity-fitness correlation at the major histocompatibility complex despite low variation in Alpine ibex (Capra ibex)

Crucial for the long-term survival of wild populations is their ability to fight diseases. Disease outbreaks can lead to severe population size reductions, which makes endangered and reintroduced species especially vulnerable. In vertebrates, the major histocompatibility complex (MHC) plays an important role in determining the immune response. Species that went through severe bottlenecks often show very low levels of genetic diversity at the MHC. Due to the known link between the MHC and immune response, such species are expected to be at particular risk in case of disease outbreaks. However, so far, only few studies have shown that low MHC diversity is correlated with increased disease susceptibility in species after severe bottlenecks. We investigated genetic variation at the MHC and its correlations with disease resistance and other fitness-related traits in Alpine ibex (Capra ibex), a wild goat species that underwent a strong bottleneck in the last century and that is known to have extremely low genetic variability, both genome-wide and at the MHC. We studied MHC variation in male ibex of Gran Paradiso National Park, the population used as a source for all postbottleneck reintroductions. We found that individual MHC heterozygosity (based on six microsatellites) was not correlated with genome-wide neutral heterozygosity. MHC heterozygosity, but not genome-wide heterozygosity, was positively correlated with resistance to infectious keratoconjunctivitis and with body mass. Our results show that genetic variation at the MHC plays an important role in disease resistance and, hence, should be taken into account for successfully managing species conservation.

Quasi-2D Heisenberg Antiferromagnets [CuX(pyz)2](BF4) with X = Cl and Br

Two Cu²⁺ coordination polymers [CuCl(pyz)₂](BF₄) 1 and [CuBr(pyz)₂](BF₄) 2 (pyz = pyrazine) were synthesized in the family of quasi two-dimensional (2D) [Cu(pyz)₂]²⁺ magnetic networks. The layer connectivity by monatomic halide ligands results in significantly shorter interlayer distances. Structures were determined by single-crystal X-ray diffraction. Temperature-dependent X-ray diffraction of 1 revealed rigid [Cu(pyz)₂]²⁺ layers that do not expand between 5 K and room temperature, whereas the expansion along the c-axis amounts to 2%. The magnetic susceptibility of 1 and 2 shows a broad maximum at ∼8 K, indicating antiferromagnetic interactions within the [Cu(pyz)₂]²⁺ layers. 2D Heisenberg model fits result in J_∥ = 9.4(1) K for 1 and 8.9(1) K for 2. The interlayer coupling is much weaker with | J_⊥| = 0.31(6) K for 1 and 0.52(9) K for 2. The electron density, experimentally determined and calculated by density functional theory, confirms the location of the singly occupied orbital (the magnetic orbital) in the tetragonal plane. The analysis of the spin density reveals a mainly σ-type exchange through pyrazine. Kinks in the magnetic susceptibility indicate the onset of long-range three-dimensional magnetic order below 4 K. The magnetic structures were determined by neutron diffraction. Magnetic Bragg peaks occur below T_N = 3.9(1) K for 1 and 3.8(1) K for 2. The magnetic unit cell is doubled along the c-axis ( k = 0, 0, 0.5). The ordered magnetic moments are located in the tetragonal plane and amount to 0.76(8) μ_B/Cu²⁺ for 1 and 0.6(1) μ_B/Cu²⁺ for 2 at 1.5 K. The moments are coupled antiferromagnetically both in the ab plane and along the c-axis. The Cu²⁺ g-tensor was determined from electron spin resonance spectra as g _x = 2.060(1), g _z = 2.275(1) for 1 and g _x = 2.057(1), g _z = 2.272(1) for 2 at room temperature.

Dipolar Spin Ice States with a Fast Monopole Hopping Rate in CdEr_{2}X_{4} (X=Se, S)

Excitations in a spin ice behave as magnetic monopoles, and their population and mobility control the dynamics of a spin ice at low temperature. CdEr_{2}Se_{4} is reported to have the Pauling entropy characteristic of a spin ice, but its dynamics are three orders of magnitude faster than the canonical spin ice Dy_{2}Ti_{2}O_{7}. In this Letter we use diffuse neutron scattering to show that both CdEr_{2}Se_{4} and CdEr_{2}S_{4} support a dipolar spin ice state-the host phase for a Coulomb gas of emergent magnetic monopoles. These Coulomb gases have similar parameters to those in Dy_{2}Ti_{2}O_{7}, i.e., dilute and uncorrelated, and so cannot provide three orders faster dynamics through a larger monopole population alone. We investigate the monopole dynamics using ac susceptometry and neutron spin echo spectroscopy, and verify the crystal electric field Hamiltonian of the Er^{3+} ions using inelastic neutron scattering. A quantitative calculation of the monopole hopping rate using our Coulomb gas and crystal electric field parameters shows that the fast dynamics in CdEr_{2}X_{4} (X=Se, S) are primarily due to much faster monopole hopping. Our work suggests that CdEr_{2}X_{4} offer the possibility to study alternative spin ice ground states and dynamics, with equilibration possible at much lower temperatures than the rare earth pyrochlore examples.

Magnetic Characterization of Direct-Write Free-Form Building Blocks for Artificial Magnetic 3D Lattices

Three-dimensional (3D) nanomagnetism, where spin configurations extend into the vertical direction of a substrate plane allow for more complex, hierarchical systems and the design of novel magnetic effects. As an important step towards this goal, we have recently demonstrated the direct-write fabrication of freestanding ferromagnetic 3D nano-architectures of ferromagnetic CoFe in shapes of nano-tree and nano-cube structures by means of focused electron beam induced deposition. Here, we present a comprehensive characterization of the magnetic properties of these structures by local stray-field measurements using a high-resolution micro-Hall magnetometer. Measurements in a wide range of temperatures and different angles of the externally applied magnetic field with respect to the surface plane of the sensor are supported by corresponding micromagnetic simulations, which explain the overall switching behavior of in part rather complex magnetization configurations remarkably well. In particular, the simulations yield coercive and switching fields that are in good quantitative correspondence with the measured coercive and switching fields assuming a bulk metal content of 100 at % consisting of bcc Co 3 Fe. We show that thermally-unstable magnetization states can be repetitively prepared and their lifetime controlled at will, a prerequisite to realizing dynamic and thermally-active magnetic configurations if the building blocks are to be used in lattice structures.

Immune mediated destruction of platelets in dogs with heat stroke: A prospective study

Objective: Severe thrombocytopenia is a common sequelae to heat stroke in dogs. So far it has been hypothezised that it is due to disseminated intravascular coagulation. We hypothezised that it is due to immune mediated destruction via antiplatelet antibodies. Material and methods: Prospective evaluation of dogs with heat stroke from May 2005 to August 2008. Dogs that developed severe thrombocytopenia within 5 days of admission were included in the study. All dogs were treated with a standardized treatment protocol. In addition, they received either immunoglobulins or prednisolone. Results: Six dogs were presented with heat stroke during that time period. Four developed a severe thrombocytopenia. All four dogs tested positive for antiplatelet antibodies and did not have elevated D-Dimers at that time. Platelet count in three dogs recovered fully, one dog was euthanized due to liver and renal failure. Conclusion: In those cases thrombocytopenia was due to immune mediated destruction not due to DIC. Clinical rele-vance: Due to the severity of the thrombocytopenia and the high risk for bleeding in those patients, immunosuppressive therapy in addition to DIC prophylaxis should be discussed.

Fallbericht und Literaturübersicht kutaner Dirofilariose

Gegenstand und Ziel: Der Fallbericht erörtert das diagnostische Vorgehen und differenzialdiagnostische Überlegungen bei Patienten mit Mikrofilarämie und negativem Dirofilaria-immitis-Antigentest und diskutiert die Infektion mit Dirofilaria repens und deren Therapie. Material und Methode: Bei einem Hund aus Ungarn wurden im Blutausstrich Mikrofilarien gefunden. Die weitere Diagnostik zur Differenzierung der Mikrofilarien umfasste einen Dirofilaria-immitis-Antigentest, eine Polymerasekettenreaktion zum Nachweis von Dirofilaria immitis und Dipetalonema reconditum sowie eine Saure-Phosphatase-Reaktion zur Diagnose einer Infektion mit Dirofilaria repens. Ergebnisse: Mittels der Saure-Phosphatase-Reaktion konnte eine Infektion mit Dirofilaria repens diagnostiziert werden. Die Therapie gegen die Mikrofilarien erfolgte mit Selamectin. Schlussfolgerung und klinische Relevanz: Bei mikrofilarämischen Patienten muss differenzialdiagnostisch neben einer Infektion mit Dirofilaria immitis eine Infektion mit anderen, weniger pathogenen Parasiten in Betracht gezogen werden, da sich die Notwendigkeit einer Therapie und das Therapieregime je nach Infektion deutlich unterscheiden.

World Health Organization cardiovascular risk stratification and target organ damage

BACKGROUND

Prediction charts allow treatment to be targeted according to simple markers of cardiovascular risk; many algorithms do not recommend screening asymptomatic target organ damage which could change dramatically the assessment.

OBJECTIVE

To demonstrate that target organ damage is present in low cardiovascular risk hypertensive patients and it is more frequent and severe as global cardiovascular risk increases.

METHODS

Consecutive hypertensive patients treated at a single Latin American center. Cardiovascular risk stratified according to 2013 WHO/ISH risk prediction chart America B. Left ventricular mass assessed by Devereux method, left ventricular hypertrophy considered >95g/m(2) in women and >115g/m(2) in men. Transmitral diastolic peak early flow velocity to average septal/lateral peak early diastolic relaxation velocity (E/e' ratio) measured cut off value >13. Systolic function assessed by tissue Doppler average interventricular septum/lateral wall mitral annulus rate systolic excursion (s wave).

RESULTS

A total of 292 patients were included of whom 159 patients (54.5%) had cardiovascular risk of <10%, 90 (30.8%) had cardiovascular risk of 10-20% and 43 (14.7%) had cardiovascular risk of >20%. Left ventricular hypertrophy was detected in 17.6% low risk patients, 27.8% in medium risk and 23.3% in high risk (p<0.05), abnormal E/e' ratio was found in 13.8%, 31.1% and 27.9%, respectively (p<0.05). Mean s wave was 8.03+8, 8.1+9 and 8.7+1cm/s for low, intermediate and high risk patients, respectively (p<0.025).

CONCLUSIONS

Target organ damage is more frequent and severe in high risk; one over four subjects was misclassified due to the presence of asymptomatic target organ damage.

Chitosan-based nanocomposites for the repair of bone defects

Chitosan scaffolds of different deacetylation degrees, average molecular weights and concentrations reinforced with silica nanoparticles were prepared for bone tissue regeneration. The resulting nanocomposites showed similar pore sizes (<300 μm) regardless the deacetylation degree and concentration used in their formulation. Their mechanical compression resistance was increased by a 30% with the addition of silica nanoparticles as nanofillers. The biocompatibility of the three-dimensional chitosan scaffolds was confirmed by the Alamar Blue assay in human primary osteoblasts as well as the formation of cell spheroids indicative of their great potential for bone regeneration. In vivo implantation of the scaffolds in a mice calvaria defect model provided substantial evidences of the suitability of these nanocomposites for bone tissue engineering showing a mature and dense collagenous tissue with small foci of mineralization, vascularized areas and the infiltration of osteoblasts and osteoclasts. Nevertheless, mature bone tissue formation was not observed after eight weeks of implantation.

Polydomy enhances foraging performance in ant colonies

Collective foraging confers benefits in terms of reduced predation risk and access to social information, but it heightens local competition when resources are limited. In social insects, resource limitation has been suggested as a possible cause for the typical decrease in per capita productivity observed with increasing colony size, a phenomenon known as Michener's paradox. Polydomy (distribution of a colony's brood and workers across multiple nests) is believed to help circumvent this paradox through its positive effect on foraging efficiency, but there is still little supporting evidence for this hypothesis. Here, we show experimentally that polydomy enhances the foraging performance of food-deprived Temnothorax nylanderi ant colonies via several mechanisms. First, polydomy influences task allocation within colonies, resulting in faster retrieval of protein resources. Second, communication between sister nests reduces search times for far away resources. Third, colonies move queens, brood and workers across available nest sites in response to spatial heterogeneities in protein and carbohydrate resources. This suggests that polydomy represents a flexible mechanism for space occupancy, helping ant colonies adjust to the environment.

Abstract P5-09-06: Ovarian reserve and response to controlled ovarian hyperstimulation (COH) in breast cancer women with and without BRCA mutation

Background: 6300 new cases of breast cancer arise in young women under 40 each year in France. Some of them are BRCA 1 or 2 mutation carriers. Most of them receive a potentially gonadotoxic chemotherapy while they have not yet completed their family. Since 2011, a systematic proposal of ovarian reserve follow-up and fertility preservation by oocyte freezing is provided to each young early breast cancer (BC) patients (pts) of our program (NCT 01614704). Preliminary results were presented at the SABCS in 2013. We now investigate the impact of BRCA mutation on the ovarian reserve and the ovarian response to simulation.

Methods: 115 young BC pts were systematically referred to a reproductive medicine centre before starting chemotherapy. Inclusion criteria were age 18 to 38, histologically confirmed invasive breast carcinoma, absence of metastases. According to their personal and familial history, genetic counselling was performed and if the patient met the criteria and agreed, BRCA genes were analysed. Pts in an adjuvant setting and who were asking for fertility preservation underwent COH during the interval between complete surgery and start of adjuvant chemotherapy. Ovarian stimulation protocol consisted in a conventional antagonist protocol with recombinant FSH starting on day 2 of the menstrual cycles. The GnRh antagonist was started on day of the COH and the final oocyte maturation was achieved by an injection of triptorelin 0.2 mg when at least 3 follicles reached 18 mm of diameter. All pts gave their informed consent for COH, egg/embryo freezing and follow-up.

Results: 115 pts achieved pre-treatment AMH and AFC assessment. 60 (52,1%) were eligible for COH in order to cryopreserve egg or embryos. BRCA analysis was performed in 83 pts. 23 did not meet the criteria or refused. 9 analyses are still in process. 17 (20.4%) pts were positive for BRCA mutation (BRCA1: 13; BRCA2: 4) and 66 were not. In the mutation carriers group (n=17), median age was 32 years (Range 25-37). Median initial AMH levels and AFC were 23 pmol/l (5.1–223) and 20 (6-100), respectively. Eight pts underwent COH. Median duration of stimulation was 9,5 days (8-13) with a median cumulative dose of gonadotropins of 2875 UI (1200-5450). The median number of vitrified oocytes was 5,5 (0-15). Two patients chose frozen embryo preservation (1 and 2 eggs respectively). In the non-carriers group (n=66), median age was 31 years (24-37). Median initial AMH levels and AFC were 23.4 pmol/l (0.8-136) and 24 (1-68). 27 pts underwent COH. Median duration of stimulation was 10 days (7-14). Dose of gonadotropins was 2700 UI (1365-5600). The median number of vitrified oocytes was 6 (0-18). The 3 patients chose eggs preservation (0.0 and 3 eggs respectively). There was no significant difference in the two groups.

Discussion/ Conclusion: Few studies stated that BRCA1 mutation may be associated with reduced ovarian reserve in healthy BRCA mutation carriers. Meirow and al concluded that both healthy and BC BRCA mutation carriers demonstrated normal ovarian response in vitro fertilization cycles. Our results show that ovarian reserve of BRCA 1/2 mutations BC carriers do not differ from that of non-carriers. Response to COH seems similar in both groups too.

Citation Format: Mailliez A, Keller L, Menu-Hespel S, Plouvier P, D'Orazio E, Basson L, Pigny P, Bonneterre J, Decanter C. Ovarian reserve and response to controlled ovarian hyperstimulation (COH) in breast cancer women with and without BRCA mutation [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-09-06.

The Genovese grading scale is not reliable for MR assessment of collagen meniscus implants

BACKGROUND

The purpose of the study was to evaluate the intra- and inter-observer reliabilities of the Genovese grading on MRI in patients after collagen meniscus substitution.

METHODS

84 MRI images of 74 consecutive patients who underwent partial meniscus substitution using collagen meniscus implant (CMI) were assessed. MRIs were evaluated using the Genovese grading system. Furthermore, meniscal extrusion was assessed. Two observers performed the grading twice, blinded to each other and to the previous results, with a six weeks interval. The inter- and intra-observer reliabilities were assessed using kappa and weighted kappa values.

RESULTS

The criterion "morphology/size" showed a weighted kappa value inter-observer reliability of 0.069 (rater 1)/0.352 (rater 2) and intra-observer reliability of 0.170 (1st rating)/0.582 (2nd rating). The criterion "signal intensity" showed a weighted kappa value inter-observer reliability of 0.175/0.284 and intra-observer reliability of 0.294/0.458. The criterion "cartilage lesions" showed a kappa value inter-observer reliability of 0.091/0.525 and intra-observer reliability of 0.409/0.413. The criterion "bone marrow edema" showed a kappa value inter-observer reliability of 0.667/0.808 and intra-observer reliability of 0.702/0.715. The criterion "cartilage lesions" showed a kappa value inter-observer reliability of 0.091/0.525 and intra-observer reliability of 0.409/0.413. Regarding meniscal extrusion kappa values for the inter-observer reliability were 0.625/0.940 and 0.625/0.889 for intra-observer reliability.

CONCLUSIONS

Three of the four Genovese grading items showed only slight to moderate inter- and intra-observer reliabilities in evaluating CMI on MRI. Hence, such grading results need to be considered with all due care. Only the criteria "bone marrow edema" and "meniscal extrusion" showed a good agreement for both inter- and intra-observer reliabilities.

A novel type of splayed ferromagnetic order observed in Yb2Ti2O7

The pyrochlore insulator Yb2Ti2O7 has attracted the attention of experimentalists and theoreticians alike for about 15 years. Conflicting neutron diffraction data on the possible existence of magnetic Bragg reflections at low temperature have been published. Here we report the observation of magnetic Bragg reflections by neutron powder diffraction at 60 mK. The magnetic diffraction pattern is analyzed using representation theory. We find Yb2Ti2O7 to be a splayed ferromagnet as reported for Yb2Sn2O7, a sibling compound with also dominating ferromagnetic interactions as inferred from the positive Curie-Weiss temperature. However, the configuration of the magnetic moment components perpendicular to the easy axis is of the all-in-all-out type in Yb2Ti2O7 while it is two-in-two-out in the Yb2Sn2O7. An overall experimental picture of the magnetic properties emerges.

Morphologic and Functional Heart Abnormalities Associated to High Modified Tei Index in Hypertensive Patients

INTRODUCTION

LV dysfunction develops early in hypertension, even previously to left ventricular remodeling.

AIMS

To determine the frequency of morphologic and functional heart abnormalities associated to abnormal modified Tei Index in untreated hypertensive (HBP) patients (p) with preserved ejection fraction (pEF).

METHODS

Case-control study. Three groups: (1) HBP without left ventricular hypertrophy (LVH); (2) HBP with LVH; (3) non-HBP controls. Ejection fraction >54 % identified pEF. LVH measured by Devereux method. Systolic and diastolic functions assessed by standard echocardiography and tissue Doppler. 2013 ESH/ESC Hypertension Guidelines normal values were considered. Tei index measured at the lateral and septal LV walls in apical 4-chamber view by tissue Doppler, value >0.40 considered abnormal.

STATISTICAL ANALYSIS

multifactorial ANOVA test adjusted by sex and age, p < 0.05 statistically significant.

RESULTS

The study included 14 controls, 88 HBP p without LVH, and 19 HBP p with LVH. The HBP p sample mean age was 58.7 ± 13.5 years and 52 (44.1 %) were males. Mean Tei Index was 0.35 ± 0.03 in controls; 0.42 ± 0.05 in HBP without LVH; and 0.42 ± 0.06 in HBP with LVH (p < 0.025). Abnormal Tei Index was present in 2p (14.3 %) controls; 64 p (72.7 %) HBP without LVH; and 15 p (78.9 %) HBP with LVH (p < 0.0009). Tissue Doppler's wave was 8.4 ± 0.9 cm/s in controls; 8 ± 1.6 cm/s in HBP without LVH and 7.8 ± 1.1 cm/s in HBP with LVH.

CONCLUSIONS

(1) Left ventricular dysfunction is frequent in HBP p, even without LVH; (2) modified tissue Doppler Tei index is a useful tool for the diagnosis of left ventricular dysfunction.