SUPT6H controls estrogen receptor activity and cellular differentiation by multiple epigenomic mechanisms.

The estrogen receptor alpha (ERα) is the central transcriptional regulator of ductal mammary epithelial lineage specification and is an important prognostic marker in human breast cancer. Although antiestrogen therapies are initially highly effective at treating ERα-positive tumors, a large number of tumors progress to a refractory, more poorly differentiated phenotype accompanied by reduced survival. A better understanding of the molecular mechanisms involved in the progression from estrogen-dependent to hormone-resistant breast cancer may uncover new targets for treatment and the discovery of new predictive markers. Recent studies have uncovered an important role for transcriptional elongation and chromatin modifications in controlling ERα activity and estrogen responsiveness. The human Suppressor of Ty Homologue-6 (SUPT6H) is a histone chaperone that links transcriptional elongation to changes in chromatin structure. We show that SUPT6H is required for estrogen-regulated transcription and the maintenance of chromatin structure in breast cancer cells, possibly in part through interaction with RNF40 and regulation of histone H2B monoubiquitination (H2Bub1). Moreover, we demonstrate that SUPT6H protein levels decrease with malignancy in breast cancer. Consistently, SUPT6H, similar to H2Bub1, is required for cellular differentiation and suppression of the repressive histone mark H3K27me3 on lineage-specific genes. Together, these data identify SUPT6H as a new epigenetic regulator of ERα activity and cellular differentiation.

Quantized spin waves in the metallic state of magnetoresistive manganites.

Spin wave measurements have been carried out in ferromagnetic (F) La(1-x)(Sr,Ca)(x)MnO(3) with x(Sr) = 0.15, 0.175, 0.2, 0.3, and x(Ca) = 0.3. In all q directions, close to the zone boundary, the spin wave spectra consist of several energy levels, with the same values in the metallic and the x approximately 1/8 doping ranges. For x(Sr) = 0.15, the data are quantitatively interpreted in terms of quantized spin waves within 2D ordered F domains or clusters of 4a size. The same picture holds in the metallic state with, however, disordered clusters embedded in a 3D F matrix.

Selective and automated sample pretreatment by molecularly imprinted polymer for the analysis of the basic drug alfuzosin from plasma.

A molecularly imprinted polymer synthesized in dichloromethane, was evaluated for the selective extraction of a pharmaceutical compound from human plasma and integrated on-line with liquid chromatography. The target drug is an alpha-blocker called alfuzosin widely used for the treatment of benign prostatic hyperplasia. By a comprehensive approach of the retention mechanism, a selective extraction procedure was established by exploiting the development of electrostatic interactions between the target analyte and the selective support in LC compatible solvents. By applying this method to plasma, extraction recoveries close to 100% were obtained for alfuzosin while various pharmaceutical compounds currently found in biological fluids were not retained on the support. The high selectivity of the support coupled to the chromatographic system permitted an easy and fast analysis of the drug with a limit of quantification of 15 microg L(-1) by UV detection.

Towards comprehensive hydrocarbons analysis of middle distillates by LC-GCxGC.

The detailed characterization of middle distillates is essential for a better understanding of reactions involved in refining processes. Owing to a higher resolution power and an enhanced sensitivity, but especially to a group-type ordering in the chromatographic plane, comprehensive two-dimensional gas chromatography (GCxGC) offers unsurpassed characterization possibilities for petroleum samples. However, GCxGC fails to totally discriminate naphthenes from unsaturates occurring in hydrotreated diesel samples. This article aims at promoting the implementation of LC-GCxGC for the quantitative determination of hydrocarbon distribution in middle distillates, including naphthenes. In this configuration, liquid chromatography (LC) enables the separation of hydrocarbons into two fractions (viz., saturated and unsaturated) before the subsequent analysis of each fraction by GCxGC. In this paper, the choice of GCxGC conditions in order to achieve the separation and identification of hydrocarbons by chemical class is discussed; under these conditions, naphthenes are separated according to the number of saturated rings. For the first time, the presence of di-, tri-, and tetra-naphthenes resulting from the hydroconversion of aromatics can clearly be evidenced. A quantitative procedure for the determination of the distribution of hydrocarbons, including the distribution of naphthenes according to the number of saturated rings, is also proposed and discussed in detail. LC-GCxGC is found to provide an unequalled degree of information that will widely contribute to a better understanding of hydroconversion processes.

Spin phonon coupling in hexagonal multiferroic YMnO3.

Inelastic neutron scattering measurements have been performed on YMnO3, aiming to study the interplay between spin and lattice degrees of freedom in this hexagonal multiferroic material. Our study provides evidence for a strong coupling between magnons and phonons, evidenced by the opening of a gap below T(N) in the dispersion of the transverse acoustic phonon mode polarized along the ferroelectric axis. The resulting upper phonon branch is found to lock on one of the spin-wave modes. These findings are discussed in terms of a possible hybridization between the two types of elementary excitations.

Low temperature charge and orbital textures in La0.875Sr0.125MnO3.

By using nuclear magnetic resonance techniques we show that for T<30 K the La0.875Sr0.125MnO3 compound displays a nonuniform charge distribution, comprised of two interconnected Mn ion subsystems with different spin, orbital, and charge couplings. The NMR results agree very well with the two spin wave stiffness constants observed at small q values in the spin wave dispersion curves [Phys. Rev. B 67, 214430 (2003)]. This picture is probably related to a yet undetermined charge and orbital superstructure occurring in the ferromagnetic insulating state of the La0.875Sr0.125MnO3 compound.

Robustness study of a reversed-phase liquid chromatographic method for the analysis of carboxylic acids in industrial reaction mixtures.

The robustness study of the reversed-phase liquid chromatographic method developed for the quantitative analysis of carboxylic acids is a real asset to prepare method transfer because it provides an indication of its reliability during routine use. Indeed, it was possible to predict the consequences of small variations in operating conditions on the responses. The design of experiments approach was applied to model the effects and interactions of a high number of factors varying simultaneously with a limited number of runs. First we identified the factors which potentially affect the chromatographic responses used for carboxylic acids quantitation: detection wavelength (lambda), column temperature (T), acetonitrile ratio in mobile phase (Me), duration of the plateau before the gradient (L) and gradient slope (S). Then we estimated the order of magnitude of realistic variations to assign factor levels. Finally a central composite design was carried out around the nominal conditions defined during method optimization. The statistical treatment of responses (retention factors, and concentrations) showed that the column temperature, the acetonitrile ratio in the mobile phase, the duration of the plateau before the gradient and the gradient slope were the most influent factors. The building of the robust domain from response-surfaces allowed us to give tolerance limits for the factors (216 nm< lambda <222 nm, 49.3 degrees C < T < 51.4 degrees C, 4.90% < Me < 5.18%, v/v, 4.5 min < L < 5.4 min, 9%< S <11%) for which the performances of the method were maintained.

Rapid polyelectrolyte-based membrane immunoassay for the herbicide butachlor.

Oppositely charged water-soluble polyelectrolytes were used in the developed membrane immunoenzyme assay for the herbicide butachlor. High-affinity and rapid binding between polyanion polymethacrylate and polycation poly(N-ethyl-4-vinylpyridinium) was applied to separate reacted and free immunoreactants. Competitive immunoassay format with peroxidase-labeled antigen was realized. The insoluble colored product of the peroxidase reaction was formed by bound labeled immune complexes and was reflectometrically detected. The assay combines short duration (15 min), high sensitivity (0.03 g/mL) and availability for out-of-laboratory testing. Different image processing algorithms were used to determine the herbicide content. Low variation coefficients of the measurements in the proposed quantitative assay, namely 4.8-9.0% for the range of antigen concentrations from 0.1 to 3.0 ng/mL, are evidence of the assay effectiveness. Possibility to control the butachlor content in mineral, artesian, and drinking water was demonstrated.

Confined spin waves reveal an assembly of nanosize domains in ferromagneticLa1-xCaxMnO3 (x=0.17,0.2).

We report a study of spin waves in ferromagnetic La1-xCaxMnO3, at concentrations x=0.17 and x=0.2 very close to the metallic transition (x=0.225). Below T(C), in the quasimetallic state (T=150 K), nearly q-independent energy levels are observed. They are characteristic of standing spin waves confined into finite-size ferromagnetic domains, defined only in the (a,b) plane for x=0.17, and in all directions for x=0.2. They allow an estimation of the domain's size, a few lattice spacings, and of the magnetic coupling constants inside the domains. These constants, anisotropic, are typical of an orbital-ordered state, allowing one to characterize the domains as "hole poor." The precursor state of the collossal magnetoresistance metallic phase appears, therefore, as an assembly of small orbital-ordered domains.

Field-induced ferromagnetic metallic state in the bilayer manganite (La0.4Pr0.6)1.2Sr1.8Mn2O7, probed by neutron scattering.

The bilayer manganite La1.2Sr1.8Mn2O7 exhibits a phase transition from a paramagnetic insulating (PI) to a ferromagnetic metallic (FM) state with a colossal magnetoresistance (CMR) effect. Upon 60% Pr substitution, magnetic order and PI to FM transition are suppressed. Application of a moderate magnetic field restores an FM state with a CMR effect. Neutron scattering by a single crystal of (La0.4Pr0.6)1.2Sr1.8Mn2O7, under a magnetic field of 5 T, has revealed a long-range and homogeneous ferromagnetic order. In the PI phase, under zero field, correlated lattice polarons have been detected. At 28 K, under 5 T, the spin wave dispersion curve determines an in-plane isotropic spin wave stiffness constant of 146 meV A(2). So the magnetic field not only generates a homogeneous ferromagnetic ground state, but also restores a magnetic coupling characteristic of FM CMR manganites.

Retention mechanism of analytes in the solid-phase extraction process using molecularly imprinted polymers. Application to the extraction of triazines from complex matrices.

Two molecularly imprinted polymers (MIPs), prepared in dichloromethane with terbutylazine and ametryn as template molecules, were evaluated for the selective extraction of triazines from complex matrices. Various parameters affecting extraction recoveries on MIPs were studied in order to obtain an optimized extraction procedure allowing to reduce non-specific interactions. In order to test the selectivity of the MIPs, the same procedure was applied to the extraction of compounds possessing the same polarity and size as the triazines. By means of molecular modeling, the effects of the electric charge distribution and of the size of the molecules on the retention mechanism were studied. The value of capacity for terbutylazine MIP was also measured. At last, the high selectivity resulting from the use of MIPs was clearly demonstrated by their applications to the clean-up of grape juice and soil extracts spiked with triazines. In addition, the soil extract was cleaned-up by immunoextraction allowing the comparison of both approaches in terms of selectivity.

Immunoaffinity solid-phase extraction for pharmaceutical and biomedical trace-analysis-coupling with HPLC and CE-perspectives.

Immunoaffinity solid-phase extraction (SPE) technique is based upon a molecular recognition mechanism. The high affinity and the high selectivity of the antigen-antibody interactions allow the specific extraction and the concentration of the analytes of interest in one step. In pharmaceutical and biological fields, where most often matrices are complex and analytes at trace-levels, this approach constitutes a unique tool for fast and solvent-free sample preparation. This review presents a general description of this extraction technique and gives numerous examples of its applications in pharmaceutical and biomedical fields. It emphasizes the on-line coupling with chromatographic and electrophoretic separation techniques and introduces new developments. The future directions, especially with regards to the current development of analytical microsystems, are discussed.

Field-induced ferromagnetic metallic state of bilayer manganite (La0.4Pr0.6)1.2Sr1.8Mn2O7: a polarized neutron diffraction study.

Unpolarized and polarized neutron diffraction measurements have been carried out on the bilayer manganite (La0.4Pr0.6)1.2Sr1.8Mn2O7 which undergoes simultaneous semiconductor-metal paraferromagnetic transitions under magnetic field. Maximum entropy magnetization density reconstruction and multipole refinement on flipping ratios evidence the existence of two distinct field-induced states. The field-induced ferromagnetic state where the field is parallel to the c axis is characterized by the presence of magnetic moment on the Sr site of 0.48(2)mu(B), due to the Pr substitution. It also shows a high population of the d3(z(2)-r(2)) orbitals of Mn3+. For the field-induced state where the field is parallel to the a or b axes no magnetization density was found at the Sr site and the dx(2)(-y(2)) orbital is slightly more populated than the d3(z(2)-r(2)) one.

Optimization of the class-selective extraction of triazines from aqueous samples using a molecularly imprinted polymer by a comprehensive approach of the retention mechanism.

Direct, selective solid-phase extraction of triazines from aqueous samples is presented using a molecularly imprinted polymer (MIP) made with terbutylazine as template molecule. After optimization of the steps of the procedure, 14 triazines including degradation products were studied and satisfactory extraction recoveries were obtained except for thiotriazines. By comparing results obtained with the terbutylazine MIP and a similar non-imprinted polymer, it was determined that retention was achieved via specific interactions except for hydroxyterbutylazine. Selectivity of the extraction procedure was also verified by applying the MIP for the extraction of phenylureas that were not retained on it. The effects of the charge distribution and of molecular volume of the triazines (obtained by molecular modeling) on the selectivity of interactions between the analytes and the MIP were studied. However, when the optimized procedure was applied to real samples, low extraction recoveries were obtained due to strong matrix effects: ion-exchange occurs between the carboxylate groups of the MIP and the ionic species of the sample, that prevents subsequent specific interactions. By introducing an acid wash step, the procedure was successfully applied for the class-selective extraction of triazines from industrial effluent and surface water samples. Finally, increased extraction recoveries were achieved for the polar degradation products of triazines by using a mixed-phase composed of a polymeric sorbent and the MIP.

Optimization, validation and comparison of various extraction techniques for the trace determination of polycyclic aromatic hydrocarbons in sewage sludges by liquid chromatography coupled to diode-array and fluorescence detection.

There is a need for a better characterization of sludges from wastewater treatment plants which are destined to be spread on agricultural lands. Inorganic pollutants are regularly controlled but organic pollutants have received few attention up to now. On this paper, we have been interested on the analysis of the 16 polycyclic aromatic hydrocarbons (PAHs) listed in the US Environmental Protection Agency (US EPA) priority list and more particularly of the six PAHs listed in the European community list (fluoranthene, benzo[b and k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene). The analysis step consists on liquid chromatography with both fluorescence and UV detections as described in the EPA Method 8310. As for the extraction step, several techniques such as supercritical fluid extraction, pressurized liquid extraction, focused microwave extraction in open vessels, Soxhlet and ultrasonic extractions are compared after optimization of the experimental conditions (solvent nature and quantity, temperature, pressure, duration, ... ) and validation with certified sludges. When optimized, these five extraction techniques are as much efficient with similar relative standard deviation. Whatever the extraction techniques used, the whole analysis protocol permits to quantify PAHs in the range of 0.09 to 0.9 mg/kg of dried sludges.

Toxicity of domoic acid in the marine mussel Mytilus edulis.

The neurotoxic, immunotoxic and genotoxic effects of domoic acid (DA) on the blue mussel Mytilus edulis were investigated by biomarkers, acethylcholinesterase (ChE) activity in gills, DNA fragmentation in digestive glands, vitality and phagocytosis activity of haemocytes in haemolymph of mussels. After intra muscular injection of DA at the concentrations ranging from 1-500 ng/g body weight (bw), no neurotoxic effect was detected within incubation times of 48 h and 7 d. The vitality of haemocytes remained in all mussels at the level of control samples within 48 h, and increased significantly after 7 d (P<0.05). At DA concentrations ranging from 1 to 100 ng/g bw haemocytes suggested a great phagocytosis activity, but no alteration in their number by both incubation times. By increasing DA concentration of 500 ng/g bw, the number of haemocytes doubled in 48 h without any change in phagocytosis activity. Primary DNA lesions in digestive glands of all injected mussels were determined in acute phase of poisoning within 48 h, and rapidly repaired after 7 d of incubation.

Picogram determination of "earthly-musty" odorous compounds in water using modified closed loop stripping analysis and large volume injection GC/MS.

"Earthy-musty" off-flavor problems in water samples are due to organic compounds present at the sub-part-per-trillion level. Numerous analytical methods such as purge and trap, liquid/liquid extraction, and closed-loop stripping analysis (CLSA) followed by GC/MS analysis have been used to determine these compounds. However, these methods offer poor sensitivity (detection limits of approximately 1 to 10 ng/L) when compared to the 20-30 pg/L of sensorial sensitivity. The purpose of this study was to develop a new method involving a modified CLSA preconcentration technique together with large volume injection GC/MS in order to attain analytical sensitivity equal to or better than olfactory sensitivity. For eight target compounds that cause taste and odor problems in water at trace levels, the method developed was linear in the 0.05-10 ng/L range and provided recoveries greater than 70% together with satisfactory repeatability. Detection limits as low as 15-30 pg/L were achieved, representing a 50-fold improvement in sensitivity as compared to current methods. The accuracy and sensitivity of the method were demonstrated in different aqueous matrixes, including raw surface water. The method was successfully applied to earthy-musty water samples that had remained unsolved by conventional techniques, thus proving its effectiveness.

Use of porous graphitic carbon coupled with mass detection for the analysis of polar phenolic compounds by liquid chromatography.

Phenolic compounds present in olive mill wastewater (OMW) need to be quantified because of their pollution capacity toward the environment. In the present study, six representative phenolic compounds of OMW were chosen to develop a LC-MS method. The high polarity of the compounds caused problems when using traditional reversed-phase liquid chromatography (RPLC). Consequently, a method was developed on another kind of chromatographic phase: Porous Graphitic Carbon (PGC) involving the use of a tetrahydrofuran (THF) gradient. The influence of THF as mobile phase in LC-MS coupling, which is not common practice, was evaluated. In Atmosperic Pressure Chemical Ionisation (APCI) in the negative ion mode, the presence of THF in the mobile phase did not degrade the MS signal of the target compounds in the conditions studied. On the contrary, an improvement was even observed when the percentage of THF increased. The proposed PGC-LC-MS method was selective and linear for the six phenolic compounds analysed with limits of quantification lower than 5 ppm in all cases. The precision was satisfactory (pooled RSD around 6%). The analyses of OMW matrix spiked sample confirmed the good performance of the proposed method.

Immunoaffinity solid-phase extraction for the trace-analysis of low-molecular-mass analytes in complex sample matrices.

Immunoaffinity solid-phase extraction (SPE) sorbents, so-called immunosorbents (ISs), are based upon molecular recognition using antibodies. Thanks to the high affinity and high selectivity of the antigen-antibody interaction, they allow a high degree of molecular selectivity and have shown to be a unique tool in the sample preparation area these last few years. Extraction and clean-up of complex biological and environmental aqueous samples are achieved in the same step and from large volumes when required. Their application to extracts from solid matrixes is solvent-free and more simple than any other clean-up procedure. Single analytes can be targeted, but since an antibody can also bind one or more analytes having structure similar to the one used for its preparation, ISs have been developed for targeting a single analyte and its metabolites. The cross-reactivity was also exploited for developing ISs that could selectively extract a whole class of structurally related compounds. This review describes the current technology used for the synthesis of the ISs, their properties and their field of application. The different parameters governing the antigen-antibody interactions and the solid-phase extraction process are discussed. Emphasis is given to the optimisation of the SPE sequence, especially to the desorption and regeneration steps. The importance of the capacity and its relationship with the analytes recovery and breakthrough volumes is highlighted for class-specific ISs. Multi-class-selective ISs are also presented. Validation studies are reviewed using various certified reference materials. Relevant examples, involving combination with chromatography in both off-line and on-line mode, illustrate the high selectivity provided in various complex matrixes. Miniaturisation is also described, since it allows high throughput of samples.

Graphitized carbons for solid-phase extraction.

The objective of this review is to provide updated information about the most important features of graphitized carbonaceous sorbents used for solid-phase extraction (SPE) of organic compounds from liquid natural matrices or extracts. The surface characteristics of graphitized carbon blacks and porous graphitic carbons are described which are responsible for the various types interactions (hydrophobic, electronic and ion-exchange) with analytes. The method development is given which is based on the prediction from liquid chromatographic retention data obtained using porous graphitic carbon. Emphasis is placed on their capability for trapping very polar and water-soluble analytes from aqueous samples. Comparison is made between carbon-based SPE sorbents and other reversed-phase materials such as octadecyl silicas and highly cross-linked copolymers. Especially, the difficulty encountered for the desorption of some strongly retained analytes is explained by LC data and solutions are given for optimizing the composition and volume of the desorption solution. Many examples illustrate the various common features of graphitized carbons which are the extraction of very polar analytes and multiresidue extractions. Some applications are specific to graphitized carbon black due to the presence of surface functional groups. They include the extraction of anionic compounds such as benzene and naphthalene sulfonates or acidic pesticides. Other applications are specific to porous graphitic carbon due to its flat and homogeneous surface. One example is the trace extraction of coplanar polychlorinated biphenyls (PCBs), dibenzo-p-dioxins and dibenzofurans from other PCB congeners.