Ligation of CD5 on resting B cells, but not on resting T cells, results in apoptosis

The CD5 molecule is expressed by a B cell subset. We have demonstrated that resting B cells do not proliferate in response to CD5 ligation, whereas cells preactivated with anti-IgM and IL-2 do so. Here, we specifically studied the effects of anti-CD5 and anti-IgM on apoptosis of CD5+ B cells. Both ligation of CD5 or of surface IgM (sIgM) resulted in apoptosis. This started earlier following ligation of CD5 than with sIgM, and both responses were time dependent. CD5-induced apoptosis was independent of the epitope recognized or the way the antibody was presented to the B cells. CD5+ B cells were more sensitive to IgM-induced apoptosis than CD5 B cells. Engagement of CD5 or CD3 expressed by T cells failed to induce apoptosis. Our data indicate differences in the function of CD5 molecules on tonsillar B cells, compared with blood T cells and suggest that cross-linking CD5 on B cell activates specific pathways responsible for apoptosis.     

Lithium neurotoxicity at low therapeutic doses Hypotheses for causes and mechanism of action following a retrospective analysis of published case reports

Lithium has been the pharmacologic treatment for the management of manic-depressive illness for many years. While the therapeutic efficacy of lithium is invaluable, it can cause a variety of neurotoxicities at normal therapeutic doses or concentrations. A systematic search through the Medline database was performed. 41 Cases of neurotoxic adverse effects of lithium at low therapeutic concentrations were observed (< 65 years, 14 males & 21 females/> 65 years, 6 females). Although a higher percentage of female subjects experienced lithium neurotoxicity, no statistically significant difference between the two groups was noted (Fisher's exact test, P = 0.07). The analysis of the data shows that among case reports of lithium neurotoxicity, drug interaction effect is an important factor. More than 50% (51.2%) of the patients received at least one neuroleptic medication with their lithium treatment, 22% received concomitantly an antidepressant, 22% an antiepileptic (carbamazepine) and 17% an anxiolytic. It is our hypothesis that these drug associations are an important contributing factor to lithium neurotoxicity. The high percentage of neurotoxicity which is associated with neuroleptics warrant caution in the daily clinical practice when these two classes of medications are combined. It is hypothesised that neuroleptics, in particular the phenothiazines, might increase lithium influx in red blood cells and that the enhanced levels of lithium in the tissue may possibly be responsible for the neurotoxic effects. Concomitant administration of medications such as neuroleptics with lithium require caution with regular clinical observations and drug plasma concentration monitoring.     

Featural Shift in Explanation-Biased Memory for Emotional Faces.

J. B. Halberstadt and P. M. Niedenthal (2001) reported that explanations of target individuals' emotional states biased memory for their facial expressions in the direction of the explanation. The researchers argued for, but did not test, a 2-stage model of the explanation effect, such that verbal explanation increases attention to facial features at the expense of higher level featural configuration, making the faces vulnerable to conceptual reintegration in terms of available emotion categories. The current 4 experiments provided convergent evidence for the "featural shift" hypothesis by examining memory for both faces and facial features following verbal explanation. Featural attention was evidenced by verbalizers' better memory for features relative to control participants and reintegration by a weaker explanation bias for features and configurally altered faces than for whole, unaltered faces. The results have implications for emotion, attribution, language, and the interaction of implicit and explicit processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Refining the Dynamic Network of T2SS Endopilus Tip Heterocomplex Combining cw-EPR and Nitroxide–GdIII Distance Measurements

The type 2 secretion system (T2SS) is a bacterial nanomachine composed of an inner membrane assembly platform, an outer membrane pore and a dynamic endopilus. T2SS endopili are organized into a homo-multimeric body formed by the major pilin capped by a heterocomplex of four minor pilins. The first model of the T2SS endopilus was recently released, even if structural dynamics insights are still required to decipher the role of each protein in the full tetrameric complex. Here, we applied continuous-wave and pulse EPR spectroscopy using nitroxide-gadolinium orthogonal labelling strategies to investigate the hetero-oligomeric assembly of the minor pilins. Overall, our data are in line with the endopilus model even if they evidenced conformational flexibility and alternative orientations at local scale of specific regions of minor pilins. The integration of different labelling strategies and EPR experiments demonstrates the pertinence of this approach to investigate protein–protein interactions in such multiprotein heterocomplexes.     

High-Throughput Screening Assisted Discovery of a Stable Layered Anti-Ferromagnetic Semiconductor: CdFeP2Se6

Recent advances in 2D magnetism have heightened interest in layered magnetic materials due to their potential for spintronics. In particular, layered semiconducting antiferromagnets exhibit intriguing low-dimensional semiconducting behavior with both charge and spin as carrier controls. However, synthesis of these compounds is challenging and remains rare. Here, first-principles based high-throughput search is conducted to screen potentially stable mixed metal phosphorous trichalcogenides (MM^′P₂X₆, where M and M^′ are transition metals and X is a chalcogenide) that have a wide range of tunable bandgaps and interesting magnetic properties. Among the potential candidates, a stable semiconducting layered magnetic material, CdFeP₂Se₆, that exhibits a short-range antiferromagnetic order at T_N = 21 K with an indirect bandgap of 2.23 eV is successfully synthesized . This work suggests that high-throughput screening assisted synthesis can be an effective method for layered magnetic materials discovery.     

Localisation of oxygen reduction sites in the case of iron long term atmospheric corrosion

In different fields of civil engineering and cultural heritage, the corrosion behaviour of century old ferrous artefacts must be accurately evaluated, especially under uncontrolled conditions. This approach requires an understanding of the role played by the several hundred micrometre thick corrosion layers formed on ancient metals. Combining the study of historical mild steels and a new re-corroding experiment using isotopic tracers, we show here that mechanisms controlling corrosion kinetics differ according to the nature and the organisation of various microscopic phases, leading to a decoupling of anodic and cathodic reaction or to a homogeneous corrosion.     

Automated resolution of nontarget analyte signals in GC x GC-TOFMS data using parallel factor analysis

We previously reported a method for the automated (objective) selection of a PARAFAC model having an appropriate number of factors for mathematical resolution of signal from a target analyte in GC x GC-TOFMS data (i.e., for an analysis in which the identity of the analyte is known a priori). While the previous target method has been successfully applied in several studies, the target method requires that the identity of the analyte be known. Also, multiple applications of the target method are required in cases where several analytes of interest are present in a single subsection of the chromatogram. Thus, having to know the analyte identity a priori restricts the applicability of the automated implementation of PARAFAC. The method presented in this report generalizes the previous method to allow analysis of one or more nontarget analyte signals in a subsection of a GC x GC-TOFMS chromatogram (i.e., for analyses when identities of analyte and interferences are not known a priori), thereby addressing and overcoming the limitations of the target method. Herein, we put the nontarget analyte PARAFAC method into theoretical context and illustrate the mechanics of the method using simulated data. We use real experimental GC x GC-TOFMS data to demonstrate the broad applicability of the method, with various analysis situations selected to illustrate challenging chemical analysis scenarios.     

Multielement stable isotope ratios (H,C, N,S) of honey from different European regions

The aim of this study as a part of the food traceability project “TRACE” funded by the EU was to investigate if honeys produced in regions with different climatic and geological characteristics could be discriminated on the basis of the isotopic data. The hydrogen, carbon, nitrogen and sulphur stable isotope ratios of 516 authentic honeys from 20 European regions are presented and discussed. As honey contains only small quantities of nitrogen and sulphur, the honey protein was precipitated in order to obtain measurable amounts of these elements. The mean hydrogen isotopic ratios of the honey protein were found to be significantly correlated with the mean hydrogen isotopic ratios of precipitation and groundwater in the production regions. Carbon isotopic ratios were influenced by climate. The sulphur stable isotope composition is clearly influenced by geographical location (sea spray effect) and surface geology of the production regions. The results show that the stable isotope ratios of the four bio-elements carbon, nitrogen, hydrogen and sulphur in honey protein can be applied to verify the origin of honey. Carbon and sulphur were identified by canonical discriminant analysis as providing the maximum discrimination between honey samples. For seven regions the percentage of correct classified samples is greater than 70%. It was concluded that the methodology in its current state can be used to provide reliable origin information.     

Confined diffusion in tubular structures analyzed by fluorescence correlation spectroscopy on a mirror

In fluorescence correlation spectroscopy (FCS) analysis it is generally assumed that molecular species diffuse freely in volumes much larger than the three-dimensional FCS observation volume. However, this standard assumption is not valid in many measurement conditions, particularly in tubular structures with diameters in the micrometer range, such as those found in living cells (organelles, dendrites) and microfluidic devices (capillaries, reaction chambers). As a result the measured autocorrelation functions (ACFs) deviate from those predicted for free diffusion, and this can shift the measured diffusion coefficient by as much as ~50% when the tube diameter is comparable with the axial extension of the FCS observation volume. We show that the range of validity of the FCS measurements can be drastically improved if the tubular structures are located in the close vicinity of a mirror on which FCS is performed. In this case a new fluctuation time in the ACF, arising from the diffusion of fluorescent probes in optical fringes, permits measurement of the real diffusion coefficient within the tubular structure without assumptions about either the confined geometry or the FCS observation volume geometry. We show that such a measurement can be done when the tubular structure contains at least one pair of dark and bright fringes resulting from interference between the incoming and the reflected excitation beams on the mirror surface. Measurement of the diffusion coefficient of the enhanced green fluorescent protein (EGFP) and IscS-EGFP in the cytoplasm of living Escherichia coli illustrates the capabilities of the technique.