Hg(II) trace electrochemical detection on gold electrode: Evidence for chloride adsorption as the responsible for the broad baseline

Investigations were performed in order to clarify the origin of the broad baseline observed during Hg(II) trace electrochemical detection on gold electrode in the presence of Cl- anions. The influence of Cl- concentration on the shape of the voltammograms was studied in the presence and in the absence of Bovine Serum Albumin (BSA) in order to bring out adsorption/desorption processes. On the basis of these experiments, and contrary to what has been proposed by several authors in the literature, it was proved that the broad baseline does not result from calomel (Hg2Cl2) formation but is rather related to an interaction between Cl- and polycrystalline Au electrode surface. The evolution of the shape of the baseline was also studied in the presence of other halide anions, namely F-, Br-, and I-. The latter two were found to induce a broad baseline similar to that recorded in the presence of Cl-. Finally, it was shown that BSA addition is not suitable for Hg(II) detection since it prevents Hg(0) deposition onto the electrode surface

Influence of the gold nanoparticles electrodeposition method on Hg(II) trace electrochemical detection

Gold nanoparticles (AuNPs) were deposited on Glassy Carbon (GC) substrate by using three electrochemical techniques: Cyclic Voltammetry (CV), Chronoamperometry (CA) and Potentiostatic Double-Pulse (PDP). For each electrodeposition method, the resulting AuNPs-modified electrodes were characterized by CV in H2SO4 and Field Emission Gun Scanning Electron Microscopy (FEG-SEM). CA was found to be the best electrodeposition mode for controlling the morphology and the density of AuNPs. The modified electrodes were used for low Hg(II) concentration detection using Square Wave Anodic Stripping Voltammetry (SWASV). AuNPs obtained by CA afforded the best amperometric response while involving the lowest amount of charge during the electrodeposition step (QAu(III)). This analytical response is correlated to both the smallest particle size (ca. 17 nm in diameter) and the highest particle density (332 particles μm−2), thus displaying high electrode effective surface area. In these optimal conditions, using a Hg(II) preconcentration time of 300 s, the nanosensor array exhibited a linearity range from 0.80 to 9.9 nM with a sensitivity of 1.16 μA nM−1. A detection limit of 0.40 nM (s/n = 3) was reached

A Novel Role for the Fifth Component of Complement (C5) in Cardiac Physiology

We have previously demonstrated that C5-deficient A/J and recombinant congenic BcA17 mice suffer from cardiac dysfunction when infected with C. albicans blastospores intravenously. During these studies we had observed that, even in the control un-infected state, BcA17 hearts displayed alterations in gene expression that have been associated with pathological cardiac hypertrophy in comparison to parental C5-sufficient C57Bl/6J (B6) mice. Of note was an increase in the expression of Nppb, a member of the fetal gene program and a decrease in the expression of Rgs2, an inhibitor of the hypertrophic response. We now report that C5-deletion has also affected the expression of other elements of the fetal gene program. Moreover deleting the C5a receptor, C5aR, has essentially the same effect as deleting C5, indicating a key role for C5a-C5aR signaling in the phenotype. Having noted a pathological phenotype in the un-infected state, we investigated the role of C5 in the response to cardiac stress. In previous studies, comparison of the expression profiles of C. albicans-infected BcA17 and similarly infected B6 hearts had revealed a paucity of cardioprotective genes in the C5-deficient heart. To determine whether this was also directly linked to C5-deficiency, we tested the expression of 5 such genes in the C. albicans-infected C5aR−/− mice. We found again that deletion of C5aR recapitulated the alterations in stress response of BcA17. To determine whether our observations were relevant to other forms of cardiac injury, we tested the effect of C5-deficiency on the response to isoproterenol-induced hypertrophic stimulation. Consistent with our hypothesis, A/J, BcA17 and C5aR−/− mice responded with higher levels of Nppa expression than B6 and BALB/c mice. In conclusion, our results suggest that an absence of functional C5a renders the heart in a state of distress, conferring a predisposition to cardiac dysfunction in the face of additional injury

Deprotonative metalation of substituted aromatics using mixed lithium-cobalt combinations

International audienceThe deprotonation of anisole was attempted using different homo- and heteroleptic TMP/Bu mixed lithium-cobalt combinations. Using iodine to intercept the metalated anisole, an optimization of the reaction conditions showed that in THF at room temperature 2 equiv of base were required to suppress the formation of the corresponding 2,2'-dimer. The origin of the dimer was not identified, but its formation was favored with allyl bromide as electrophile. The metalated anisole was efficiently trapped using iodine, anisaldehyde, and chlorodiphenylphosphine, and moderately employing benzophenone, and benzoyl chloride. 1,2-, 1,3- and 1,4-dimethoxybenzene were similarly converted regioselectively to the corresponding iodides. It was observed that 2-methoxy- and 2,6-dimethoxypyridine were more prone to dimerization than the corresponding benzenes when treated similarly. Involving ethyl benzoate in the metalation-iodination sequence showed the method was not suitable to functionalize substrates bearing reactive functions

Saint-Pierre – Centre de découverte de la Terre

C’est dans le cadre du projet de construction du Centre de découverte de la Terre, mené et financé par le Conseil général de la Martinique, qu’ont été réalisées les fouilles archéologiques du 27 septembre 2001 au 25 janvier 2002. En effet, le projet, comprenant la réalisation de quatre bâtiments qui présenteront les phénomènes géophysiques ou climatiques les plus spectaculaires, sur le thème du volcanisme, doit s’implanter sur une zone archéologique sensible. L’implantation des édifices porta..

Développement d'un modèle de tumeur oculaire dans un hydrogel pour les mesures de dose en brachythérapie du mélanome uvéal

Le mélanome uvéal est la tumeur primaire intraoculaire la plus fréquente chez l'adulte. L'un des traitements le plus souvent utilisé afin d'obtenir un contrôle local de la tumeur s'appelle la curiethérapie par plaque. Malgré un faible taux de récidive locale avec cette technique, la grande majorité des patients développeront des complications oculaires secondaires à la radiation cinq ans après le diagnostic initial. Le manque de modèles ex vivo ou in vitro de mélanome uvéal rend difficile la validation de plaques de curiethérapie personnalisées et le calcul des différents profils de dose par les algorithmes Monte-Carlo. Un fantôme dosimétrique bio-imprimé représentant l'œil humain contenant une tumeur uvéale de forme définie serait un modèle in vitro optimal pour l'évaluation de différents profils de dose dans le développement de plaques de curiethérapie personnalisées. Dans cette étude, la viabilité et la prolifération des cellules cancéreuses du mélanome uvéal ainsi que des fibroblastes et mélanocytes choroïdiens en culture dans un environnement tridimensionnel, soit une matrice extracellulaire commerciale (Matrigel®) ou un hydrogel imprimable, ont d'abord été mesurées par microscopie en contraste de phase ou en fluorescence. Ensuite, l'expression de marqueurs de prolifération, d'hypoxie et de dommages à l'ADN a été déterminée dans les cellules cancéreuses du mélanome uvéal cultivées en monocouche ou enrobées dans le Matrigel®, dans l'optique future d'étudier ces marqueurs lors de l'irradiation du modèle bio-imprimé de tumeur uvéale avec une plaque personnalisée. L'évaluation chirurgicale de prototypes de plaques de curiethérapie non radioactives a été faite afin de comparer les différentes itérations entre elles et aux plaques conventionnelles. Enfin, les caractéristiques à améliorer pour le développement d'un modèle biologique contenant une tumeur uvéale ont été discutées et les aspects techniques problématiques des premières plaques imprimées ont été identifiés afin d'optimiser les prochains prototypes de plaques personnalisées. Mes travaux représentent un avancement des connaissances sur les modèles in vitro 3D du mélanome uvéal et le traitement de cette tumeur oculaire par curiethérapie par plaque. Mon mémoire pourra servir de base aux projets subséquents visant soit i) à élucider l'impact des interactions des cellules cancéreuses avec leur microenvironnement sur la résistance thérapeutique de ce cancer ou ii) à tester de nouvelles stratégies thérapeutiques sur un modèle bio-imprimé de mélanome uvéal primaire.Uveal melanoma is the most common primary intraocular tumor in adults. One of the treatments most often used to achieve local tumor control is called plaque brachytherapy. Despite a low local recurrence rate with this technique, most patients will develop ocular complications secondary to radiation five years after the initial diagnosis. The lack of ex vivo or in vitro models of uveal melanoma makes it difficult to validate personalized brachytherapy plates and to calculate the different dose profiles by Monte-Carlo algorithms. A bioprinted dosimetry phantom representing the human eye containing a defined uveal tumor would be an optimal in vitro model for the evaluation of different dose profiles in the development of personalized brachytherapy plates. In this study, the viability and proliferation of uveal melanoma cells, as well as choroidal fibroblasts and melanocytes in culture in a three-dimensional environment, either a commercial extracellular matrix (Matrigel®) or a printable hydrogel, were first measured by phase contrast or fluorescence microscopy. Then, the expression of markers of proliferation, hypoxia and DNA damage was determined in uveal melanoma cells cultured as monolayer or embedded in Matrigel®, in the future perspective of studying these markers after the irradiation of the bioprinted uveal tumor model using a personalized plate. The surgical evaluation of prototypes of non-radioactive brachytherapy plates was done in order to compare the different iterations with each other and with conventional plates. Finally, the characteristics to be improved for the development of a biological model containing an uveal tumor were discussed, and the problematic technical aspects of the printed plates were identified in order to optimize the next prototypes of personalized plates. My work represents an advancement of knowledge on in vitro 3D models of uveal melanoma and the treatment of this ocular tumor by plaque brachytherapy. My master's thesis could serve as a basis for subsequent projects aiming either i) to elucidate the impact of interactions of cancer cells with their microenvironment on the therapeutic resistance of this cancer or ii) to test new therapeutic strategies on a bioprinted model of primary uveal melanoma

HARPO: a TPC as a gamma-ray telescope and polarimeter

A gas Time Projection Chamber can be used for gamma-ray astronomy with excellent angular-precision and sensitivity to faint sources, and for polarimetry, through the measurement of photon conversion to $e^+e^-$ pairs. We present the expected performance in simulations and the recent development of a demonstrator for tests in a polarized photon beam.Comment: SPIE Astronomical Telescopes + Instrumentation, Ultraviolet to gamma ray, Montr\'eal, Canada 2014. v2: note added in proof. Copyright 2014 SPIE. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibite