High-pressure melting experiments of Fe3S and a thermodynamic model of the Fe-S liquids for the Earth's core.

Melting experiments on Fe3S were conducted to 75 GPa and 2800 K in laser-heated and internally resistive-heated diamond anvil cells within-situx-ray diffraction and/or post-mortem textural observation. From the constrained melting curve, we assessed the thermal equation of state for Fe3S liquid. Then we constructed a thermodynamic model of melting of the system Fe-Fe3S including the eutectic relation under high pressures based on our new experimental data. The mixing properties of Fe-S liquids under high pressures were evaluated in order to account for existing experimental data on eutectic temperature. The results demonstrate that the mixing of Fe and S liquids are nonideal at any core pressure. The calculated sulphur content in eutectic point decreases with increasing pressure to 120 GPa and is fairly constant of 8 wt% at greater pressures. From the Gibbs free energy, we derived the parameters to calculate the crystallising point of an Fe-S core and its isentrope, and then we calculated the density and the longitudinal seismic wave velocity (Vp) of these liquids along each isentrope. While Fe3S liquid can account for the seismologically constrained density andVpprofiles over the outer core, the density of the precipitating phase is too low for the inner core. On the other hand, a hypothetical Fe-S liquid core with a bulk composition on the Fe-rich side of the eutectic point cannot represent the density andVpprofiles of the Earth's outer core. Therefore, Earth's core cannot be approximated by the system Fe-S and it should include another light element.

Effects of carbamazepine and metabolites on IL-2, IL-5, IL-6, IL-10 and IFN-γ secretion in epileptic patients: the influence of co-medication.

Carbamazepine is a widely used anticonvulsive agent. Its metabolic pathway leads not only to the major active metabolite, carbamazepine-10,11-epoxide, but also to minor terminal metabolites such as iminostilbene and acridine. Carbamazepine is usually well-tolerated, but it may lead to rare, but serious, hypersensitive reactions associated with hypereosinophilia. The mechanisms of hypersensitivity reactions to carbamazepine are still largely unknown, and the implications of the cell-mediated immune response (Th1 pathway) or the humoral immune response (Th2 pathway) are still not understood in these reactions. It is also unclear whether the parent drug or its subsequent metabolites are the primary trigger agent. In our study, we performed ex vivo experiments to evaluate the stimulation of cytokine secretion by carbamazepine, carbamazepine-10,11-epoxide, iminostilbene and acridine. IL-5, IL-6 and IL-10 were quantified as markers of the Th2 pathway, and IL-2 and IFN-γ were used as markers of the Th1 pathway. Blood samples (n=24) were obtained from epileptic patients routinely treated with carbamazepine alone or co-treated with lamotrigine or valproate. The concentrations of cytokines in the plasma were determined before and after 3 h stimulation with drugs. We found a significantly positive effect of co-treatment with valproate on the basal level of IL-5 (p<0.01) and IL-10 (p<0.05). IL-5 production increased only in blood stimulated with a high level of acridine (33 µM), whereas IL-6 production was less specifically stimulated (p<0.05). Because IL-5 is the most potent stimulating factor of the eosinophils, we suggest that the potential helper effect of valproate and acridine can lead to hypersensitive reactions to carbamazepine in the context of the humoral immune response.

Comparison of carbamazepine and oxcarbazepine effects on aminothiol levels.

OBJECTIVE: The aim of our study was to investigate the effects of carbamazepine (CBZ) and oxcarbazepine (OXCBZ) on aminothiol levels, including homocysteine (Hcy), cysteine, and cysteinylglycine, in chronically treated patients. METHODS: Epileptic patients receiving CBZ or OXCBZ were recruited as part of routine clinical practice. Demographic data and concomitant medications were recorded from the patient medical file. RESULTS: Sixty patients were included in the study; 30 patients were treated with CBZ and 30 with OXCBZ. Median Hcy level was significantly higher in CBZ-treated patients (20.6 micromol/l) than in OXCBZ-treated patients (14.0 micromol/l, p < 0.0001). No correlation was evidenced between antiepileptic drugs or metabolite levels and Hcy levels for each group. CONCLUSIONS: Less change observed with OXCBZ compared with CBZ on aminothiol levels could constitute an advantage for OXCBZ treatment in patients with other factors influencing Hcy levels and/or at high risk for cardiovascular diseases.

Liquid chromatography-electrospray mass spectrometry determination of ibogaine and noribogaine in human plasma and whole blood. Application to a poisoning involving Tabernanthe iboga root.

A liquid chromatography/electrospray ionization mass spectrometry (LC-ESI-MS) method was developed for the first time for the determination of ibogaine and noribogaine in human plasma and whole blood. The method involved solid phase extraction of the compounds and the internal standard (fluorescein) from the two matrices using OasisHLB columns. LC separation was performed on a Zorbax eclipse XD8 C8 column (5 microm) with a mobile phase of acetonitrile containing 0.02% (v/v) trimethylamine and 2mM ammonium formate buffer. MS data were acquired in single ion monitoring mode at m/z 311.2, 297.2 and 332.5 for ibogaine, noribogaine and fluorescein, respectively. The drug/internal standard peak area ratios were linked via a quadratic relationship to plasma (0.89-179 microg/l for ibogaine; 1-200 microg/l for noribogaine) and to whole blood concentrations (1.78-358 microg/kg for ibogaine; 2-400 microg/kg for noribogaine). Precision ranged from 4.5 to 13% and accuracy was 89-102%. Dilution of the samples had no influence on the performance of the method. Extraction recoveries were > or =94% in plasma and > or =57% in whole blood. The lower limits of quantitation were 0.89 microg/l for ibogaine and 1 microg/l for noribogaine in plasma, and 1.78 microg/kg for ibogaine and 2 microg/kg for noribogaine in whole blood. In frozen plasma samples, the two drugs were stable for at least 1 year. In blood, ibogaine and noribogaine were stable for 4h at 4 degrees C and 20 degrees C and 2 months at -20 degrees C. The method was successfully used for the analysis of a poisoning involving Tabernanthe iboga root.

PIN-bodies: a new class of antibody-like proteins with CD4 specificity derived from the protein inhibitor of neuronal nitric oxide synthase.

By inserting the CB1 paratope-derived peptide (PDP) from the anti-CD4 13B8.2 antibody binding pocket into each of the three exposed loops of the protein inhibitor of neuronal nitric oxide synthase (PIN), we have combined the anti-CD4 specificity of the selected PDP with the stability, ease of expression/purification, and the known molecular architecture of the phylogenetically well-conserved PIN scaffold protein. Such "PIN-bodies" were able to bind CD4 with a better affinity and specificity than the soluble PDP; additionally, in competitive ELISA experiments, CD4-specific PIN-bodies were more potent inhibitors of the binding of the parental recombinant antibody 13B8.2 to CD4 than the soluble PDP. The efficiency of CD4-specific CB1-inserted PIN-bodies was confirmed in biological assays where these constructs showed higher potencies to block antigen presentation by inhibition of IL-2 secretion and to inhibit the one-way and two-way mixed lymphocyte reactions, compared with soluble anti-CD4 PDP CB1. Insertion of the PDP into the first exposed loop (position 33/34) of PIN appeared to be the most promising scaffold. Taken together, our findings demonstrate that the PIN molecule is a suitable scaffold to expose new peptide loops and generate small artificial ligand-binding products with defined specificities.

Liquid chromatography-electrospray mass spectrometry determination of carbamazepine, oxcarbazepine and eight of their metabolites in human plasma.

Carbamazepine (CBZ) and oxcarbazepine (OXCBZ) are both antiepileptic drugs, which are prescribed as first-line drugs for the treatment of partial and generalized tonic-clonic epileptic seizures. In this paper, a specific and sensitive liquid chromatography-electrospray ionization mass spectrometry method was described for the simultaneous determination of carbamazepine (CBZ), oxcarbazepine (OXCBZ) and eight of their metabolites [CBZ-10,11-epoxide (CBZ-EP), 10,11-dihydro-10,11-trans-dihydroxy-carbamazepine (DiOH-CBZ), 10-hydroxy-10,11-dihydroCBZ (10-OH-CBZ), 2-hydroxycarbamazepine (2-OH-CBZ), 3-hydroxycarbamazepine (3-OH-CBZ), iminostilbene (IM), acridone (AO) and acridine (AI)] in human plasma. The work-up procedure involved a simple precipitation with acetone. Separation of the analytes was achieved within 50 min using a Zorbax eclipse XD8 C8 analytical column. The mobile phase consisted of a mixture of acetonitrile-formate buffer (2 mM, pH 3). Detection was performed using a quadrupole mass spectrometer fitted with an electrospray ion source. Mass spectrometric data were acquired in single ion recording mode at m/z 237 for CBZ, m/z 180 for CBZ-EP and AI, m/z 236 for OXCBZ, m/z 237 for 10-OH-CBZ, m/z 253 for 2-OH-CBZ, 3-OH-CBZ and DiOH-CBZ, m/z 196 for AO and m/z 194 for IM. For all analytes, the drug/internal standard peak height ratios were linked via a quadratic relationship to plasma concentrations. The extraction recovery averaged 90% for CBZ, 80% for OXCBZ and was 80-105% for the metabolites. The lower limit of quantitation was 0.5mg/l for CBZ, 0.4 mg/l for OXCBZ and ranged from 0.02 to 0.3 mg/l for the metabolites. Precision ranged from 2 to 13% and accuracy was between 86 and 112%. This method was found suitable for the analysis of plasma samples collected during therapeutic drug monitoring of patients treated with CBZ or OXCBZ.