Mise en ordre magnétique dans de nouveaux oxychlorures de baryum-cobalt à valences mixtes

National audienceLes structures magnétiques de deux nouveaux oxychlorures de baryum cobalt à valence mixte: Ba6Co6ClO16 (P-6m2, a=5,676(1) Å et c=14,457(2) Å) et Ba5Co5ClO13 (P63/mmc, a=5,698(1) Å et c=24,469(5) Å) ont été résolues par diffraction des neutrons. Les structures nucléaires de ces composés sont particulièrement similaires avec la présence de blocs oligomères Co4O15 ou Co3O12 connectés entre eux via des dimères tétraédriques Co2O7. Pour chacun des composés, des mesures de susceptibilité magnétique en fonction de la température ont montré l'existence d'une transition paramagnétique antiferromagnétique à basse température. Cette transition trouve son origine dans la mise en ordre antiferromagnétique des unités tétraédriques Co2O7

Bone events and evolution of biologic markers in Gaucher disease before and during treatment

25 pagesInternational audienceINTRODUCTION : Known biomarkers of Gaucher-disease activity are platelets, chitotriosidase, angiotensin-converting enzyme (ACE), tartrate-resistant acid phosphatase (TRAP) and ferritin. The aim of this study was to retrospectively evaluate the frequency of bone events (BE) and biomarker changes during two periods: diagnosis to first enzyme-replacement therapy (ERT) and the latter to the closing date. METHODS : BE of 62 treated patients, among the 73-patient cohort followed at Beaujon Hospital, Clichy, France, were described with Kaplan-Meier curves, and linear-mixed models were used to analyze their biomarker changes and the influence of several covariates (splenectomy, diagnosis year, genotype, age at diagnosis and sex). RESULTS : BE occurred before (54 events in 21 patients), but also during, ERT (12 events in 10 patients), with respective frequencies (95% confidence interval) at 10 years of 22.4% (13.3 to 36.3) and 20.0% (10.2 to 36.9). Biomarker slope changes before and during ERT differed significantly for platelets (+190/mm3/year and 7,035/mm3/year, respectively; P < 0.0001) and ferritin (+4% and -14%; P < 0.0001). High ferritin levels and low platelet counts at ERT onset were significantly associated with BE during ERT (P = 0.019 and 0.039, respectively). Covariates significantly influenced biomarker changes (baseline and/or slope): splenectomy affected platelets (baseline and changes), TRAP changes and chitotriosidase changes; diagnosis date influenced ACE and TRAP baseline values; and genotype influenced chitotriosidase baseline and changes. CONCLUSIONS : Platelet counts and ferritin levels and their slope changes at ERT onset seem to predict BE during treatment. Biomarker baseline values and changes are dependent on several covariables

Magnetic hexamers interacting in layers in the (Na,K)2_2Cu3_3O(SO4)3_4)_3 minerals

Magnetic properties and underlying magnetic models of the synthetic A$_2$Cu$_3$O(SO$_4)_3$ fedotovite (A = K) and puninite (A = Na) minerals, as well as the mixed euchlorine-type NaKCu$_3$O(SO$_4)_3$ are reported. We show that all these compounds contain magnetic Cu$_6$ hexamer units, which at temperatures below about 100 K act as single spin-1 entities. Weak interactions between these magnetic molecules lead to long-range order below $T_N$ = 3.4 K (A = Na), 4.7 K (A = NaK), and about 3.0 K (A = K). The formation of the magnetic order is elucidated by ab initio calculations that reveal two-dimensional inter-hexamer interactions within crystallographic $bc$ planes. This model indicates the presence of a weakly distorted square lattice of $S=1$ magnetic ions and challenges the earlier description of the A$_2$Cu$_3$O(SO$_4)_3$ minerals in terms of Haldane spin chains.Comment: published version, re-worked compared to the initial submissio

Complex magnetism in Ni₃TeO₆-type Co₃TeO₆ and high-pressure polymorphs of Mn_3-xCo_xTeO₆ solid solutions

International audienceNew Ni3TeO6-type (NTO) and double perovskite (DPv) polymorphs of Co3TeO6 are synthesised at pressures of 15 GPa. A complex elliptic helical magnetic order is observed in the NTO polymorph (TN1 = 58 K) that reorientates (42 K) and further splits (TN2 = 23.5 K) creating a coexisting helix. Increasing Co content within the Mn3-xCoxTeO6 system changes the dominant DPv phase to NTO structural type and drastically modifies the magnetic behaviour. DPv Co3TeO6 is the first A-site double cobaltite

Oxocentered Cu(II) lead selenite honeycomb lattices hosting Cu(I)Cl2 groups obtained by chemical vapor transport reactions

Chemical vapor transport (CVT) reactions were used to prepare three modular mixed-valent Cu(I)-Cu(II) compounds, (Pb2Cu(2+)9O4)(SeO3)4(Cu(+)Cl(2))Cl5 (1), (PbCu(2+)5O2)(SeO3)2(Cu(+)Cl2)Cl3 (2), and (Pb(x)Cu(2+)(6-x)O2)(SeO3)2(Cu(+)Cl2)K(1-x)Cl(4-x) (x = 0.20) (3). In their crystal structures chains of anion-centered (OCu(2+)4) and (OCu(2+)3Pb) tetrahedra form honeycomb-like double layers with cavities occupied by linear [Cu(+)Cl2](-) groups

Changes in liver mitochondrial plasticity induced by brain tumor

BACKGROUND: Accumulating data suggest that liver is a major target organ of systemic effects observed in the presence of a cancer. In this study, we investigated the consequences of the presence of chemically induced brain tumors in rats on biophysical parameters accounting for the dynamics of water in liver mitochondria. METHODS: Tumors of the central nervous system were induced by intraveinous administration of ethylnitrosourea (ENU) to pregnant females on the 19th day of gestation. The mitochondrial crude fraction was isolated from the liver of each animal and the dynamic parameters of total water and its macromolecule-associated fraction (structured water, H(2)Ost) were calculated from Nuclear Magnetic Resonance (NMR) measurements. RESULTS: The presence of a malignant brain tumor induced a loss of water structural order that implicated changes in the physical properties of the hydration shells of liver mitochondria macromolecules. This feature was linked to an increase in the membrane cholesterol content, a way to limit water penetration into the bilayer and then to reduce membrane permeability. As expected, these alterations in mitochondrial plasticity affected ionic exchanges and led to abnormal features of mitochondrial biogenesis and caspase activation. CONCLUSION: This study enlightens the sensitivity of the structured water phase in the liver mitochondria machinery to external conditions such as tumor development at a distant site. The profound metabolic and functional changes led to abnormal features of ion transport, mitochondrial biogenesis and caspase activation

Using Pharmacokinetic and Viral Kinetic Modeling To Estimate the Antiviral Effectiveness of Telaprevir, Boceprevir, and Pegylated Interferon during Triple Therapy in Treatment-Experienced Hepatitis C Virus-Infected Cirrhotic Patients.: Effectiveness of triple therapy in cirrhotic patients

International audienceTriple therapy combining a protease inhibitor (PI) (telaprevir or boceprevir), pegylated interferon (PEG-IFN), and ribavirin (RBV) has dramatically increased the chance of eradicating hepatitis C virus (HCV). However, the efficacy of this treatment remains suboptimal in cirrhotic treatment-experienced patients. Here, we aimed to better understand the origin of this impaired response by estimating the antiviral effectiveness of each drug. Fifteen HCV genotype 1-infected patients with compensated cirrhosis, who were nonresponders to prior PEG-IFN/RBV therapy, were enrolled in a nonrandomized study. HCV RNA and concentrations of PIs, PEG-IFN, and RBV were frequently assessed in the first 12 weeks of treatment and were analyzed using a pharmacokinetic/viral kinetic model. The two PIs achieved similar levels of molar concentrations (P = 0.5), but there was a significant difference in the 50% effective concentrations (EC50) (P = 0.008), leading to greater effectiveness for telaprevir than for boceprevir in blocking viral production (99.8% versus 99.0%, respectively, P = 0.002). In all patients, the antiviral effectiveness of PEG-IFN was modest (43.4%), and there was no significant contribution of RBV exposure to the total antiviral effectiveness. The second phase of viral decline, which is attributed to the loss rate of infected cells, was slow (0.19 day(-1)) and was higher in patients who subsequently eradicated HCV (P = 0.03). The two PIs achieved high levels of antiviral effectiveness. However, the suboptimal antiviral effectiveness of PEG-IFN/RBV and the low loss of infected cells suggest that a longer treatment duration might be needed in cirrhotic treatment-experienced patients and that a future IFN-free regimen may be particularly beneficial in these patients