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461.
Emilie Bigorgne Laurent Foucaud Céline Caillet Laure Giambérini Johanne Nahmani Fabien Thomas Fran?ois Rodius 《Journal of nanoparticle research》2012,14(7):1-17
An in vitro approach using c?lomocytes of Eisenia fetida was investigated to evaluate toxicity of TiO2 nanoparticles. C?lomocytes were exposed to well-dispersed suspension of small aggregates (130?nm) of TiO2 nanoparticles (1?C25???g/ml) during 4, 12 and 24?h. Intracellular localisation suggested that the main route of uptake was endocytosis. Cellular responses showed that TiO2 nanoparticles were not cytotoxic and had no effect on phagocytosis at any of the four concentrations for each time tested. Concerning molecular responses, an increase of fetidin and metallothionein mRNA expression was observed starting from 4?h of exposure. In contrast, expression of coelomic cytolytic factor mRNA decreased for 10 and 25???g/ml after 4?h. Superoxide dismutase, catalase and glutathione-S-transferase expression were not modified suggesting that oxidative stress was not induced by TiO2 in our experimental conditions. This in vitro approach showed that TiO2 nanoparticles were taken up by c?lomocytes and they could modify the molecular response of immune and detoxification system. 相似文献
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To understand the skin sensitization mechanism of 15-hydroperoxyabietic acid, the major allergen in colophony, we first examined the formation of potential reactive radicals derived from its reaction with light, heat and TPP-Fe3+. Trapping with 1,1,3,3-tetramethylisoindolin-2-yloxyl nitroxide confirmed the formation of carbon-centred radicals derived from allyloxyl/allylperoxyl radicals as a consequence of the hydroperoxide scission. Particular interest was further given to the reactivity with Fe(II)/Fe(III) due to the biological importance of haem containing enzymes. Using a monocyclic 15-hydroperoxyabietic acid-like compound as a model of allergenic allylic hydroperoxides, we evidenced, by the ESR spin-trapping technique, the competition between carbon and oxygen-centred radicals formed in the presence of Fe(II)/Fe(III) in organic/aqueous media. We complemented the study by showing the possibility of formation, via a radical mechanism induced by ferric chloride, of an adduct between the allylic hydroperoxide and N-acetyl-cysteine ethyl ester. The results gave new knowledge on the possible generation of highly reactive radicals that could lead to the formation of antigenic structures. 相似文献
465.
Valérie Sauvinet Laure Gabert Du Qin Corinne Louche‐Pélissier Martine Laville Michel Désage 《Rapid communications in mass spectrometry : RCM》2009,23(23):3855-3867
A reference method to accurately define kinetics in response to the ingestion of glucose in terms of total, exogenous and endogenous glucose is to use stable‐isotope‐labelled compounds such as 2H and 13C glucose followed by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) analysis. The use of the usual pentaacetyl (5Ac) derivative generates difficulties in obtaining accurate and reproducible results due to the two chromatographic peaks for the syn and anti isomers, and to the isotopic effect occurring during acetylation. Therefore, the pentaacetylaldononitrile derivative (Aldo) was validated for both isotopes, and compared with the 5Ac derivative. A correction factor including carbon atom dilution (stoichiometric equation) and the kinetic isotopic effect (KIE) was determined. Analytical validation results for the 2H GC/MS and 13C GC/C/IRMS measurements produced acceptable results with both derivatives. When 2H enrichments of plasma samples were ≤1 mol % excess (MPE), the repeatability (RSDAldo Intra assay and Intra day <0.94%, RSD5Ac Intra assay and Intra day <3.29%), accuracy (Aldo <3.4%, 5Ac <29.0%), and stability of the derivatized samples were significantly better when the Aldo derivatives of the plasma samples were used (p < 0.05). When the glucose kinetics were assessed in nine human subjects, after glucose ingestion, the plasma glucose 2H enrichments were identical with both derivatives, whereas the 13C enrichments needed a correction factor to fit together. Due to KIE variation, this correction factor was not constant and had to be calculated for each batch of analyses, to obtain satisfactory results. Mean quantities of exogenous glucose exhibit marked difference (20.9 ± 1.3g (5Ac) vs. 26.7 ± 2.5g (Aldo)) when calculated with stoichiometric correction, but fit perfectly when calculated after application of the correction factor (22.1 ± 1.3g (5Ac) vs. 22.9 ± 1.9g (Aldo)). Finally, the pentaacetylaldononitrile derivative, used here in GC/C/IRMS for the first time, enables measurement of 2H and 13C enrichments in plasma glucose with a single sample preparation. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
466.
Azebaze AG Meyer M Valentin A Nguemfo EL Fomum ZT Nkengfack AE 《Chemical & pharmaceutical bulletin》2006,54(1):111-113
Further study of the methanol extract of the stem bark of Allanblackia monticola STANER L.C. resulted in the isolation of a new prenylated xanthenedione, designated allanxanthone C, together with the five known xanthones, garciniafuran, tovophyllin A, rubraxanthone, norcowanin and mangostin and one saponin, stigmasterol-3-O-beta-D-glucopyranoside. The structure of the new compound was established by detailed spectroscopic analysis to be 1,2-dihydro-3,6,8-trihydroxy-1,1,7-tri(3-methylbut-2-enyl)xanthen-2,9-dione (3-hydroxyapetalinone C). The methanol extract and pure compounds were tested on two strains of Plasmodium falciparum, F32 (chloroquine sensitive) and FcM29 (chloroquine resistant). The IC50 values obtained ranged from 0.6 to 8.9 microg/ml. Their cytotoxicity was estimated on human melanoma cells (A375) and the cytotoxicity/antiplasmodial ratio was found to be between 15.45 and 30.46. The antimicrobial activities against a range of microorganisms of the crude extract and some of these compounds are also reported. 相似文献
467.
In domains with topography, inertial and internal waves exhibit interesting features. In particular, numerical and lab experiments show that, in two dimensions, for generic forcing frequencies, these waves concentrate on attractors. The goal of this paper is to analyze mathematically this behavior, using tools from spectral theory and microlocal analysis.© 2019 Wiley Periodicals, Inc. 相似文献
468.
Philippe Carmona Laure Coutin G. Montseny 《Statistical Inference for Stochastic Processes》2000,3(1-2):161-171
We study a class of processes which have a moving average representation with respect to a fixed driving martingale, and can be represented as a mixture of semi-martingale processes. When the driving martingale is Gaussian we obtain a numerically efficient approximation scheme and a central limit theorem (a typical process in this class is fractional Brownian motion). 相似文献
469.
Laure Fauch Ervin Nippolainen Alexei A. Kamshilin Markku Hauta-Kasari Jussi Parkkinen Timo Jääskeläinen 《Optical Review》2007,14(4):243-245
Accurate color classification by vector subspace method was implemented by simple optical system including computer controlled
set of light-emitting diodes and a photo-receiver operating in the integration regime. The technique is capable for fast and
precise classification of color distribution within two-dimensional frame with high spatial resolution. The feasibility of
the proposed system is shown by a test of four metameric colors, which were correctly distinguished. 相似文献
470.