93 research outputs found
Observation of direct-photon collective flow in sqrt(s_NN)=200 GeV Au+Au collisions
The second Fourier component v_2 of the azimuthal anisotropy with respect to
the reaction plane was measured for direct photons at midrapidity and
transverse momentum (p_T) of 1--13 GeV/c in Au+Au collisions at sqr(s_NN)=200
GeV. Previous measurements of this quantity for hadrons with p_T < 6 GeV/c
indicate that the medium behaves like a nearly perfect fluid, while for p_T > 6
GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence
for parton energy loss. In this measurement with the PHENIX detector at the
Relativistic Heavy Ion Collider we find that for p_T > 4 GeV/c the anisotropy
for direct photons is consistent with zero, as expected if the dominant source
of direct photons is initial hard scattering. However, in the p_T < 4 GeV/c
region dominated by thermal photons, we find a substantial direct photon v_2
comparable to that of hadrons, whereas model calculations for thermal photons
in this kinematic region significantly underpredict the observed v_2.Comment: 384 authors, 6 pages, 3 figures, and 1 table. Submitted to Phys. Rev.
Lett. v2 has minor changes to match the submission version. Plain text data
tables for the points plotted in the figures are publicly available at
http://www.phenix.bnl.gov/phenix/WWW/info/data/ppg126_data.htm
Suppression of back-to-back hadron pairs at forward rapidity in d+Au Collisions at sqrt(s_NN)=200 GeV
Back-to-back hadron pair yields in d+Au and p+p collisions at sqrt(s_NN)=200
GeV were measured with the PHENIX detector at the Relativistic Heavy Ion
Collider. Rapidity separated hadron pairs were detected with the trigger hadron
at pseudorapidity |eta|<0.35 and the associated hadron at forward rapidity
(deuteron direction, 3.0<eta<3.8). Pairs were also detected with both hadrons
measured at forward rapidity; in this case the yield of back-to-back hadron
pairs in d+Au collisions with small impact parameters is observed to be
suppressed by a factor of 10 relative to p+p collisions. The kinematics of
these pairs is expected to probe partons in the Au nucleus with low fraction x
of the nucleon momenta, where the gluon densities rise sharply. The observed
suppression as a function of nuclear thickness, p_T, and eta points to cold
nuclear matter effects arising at high parton densities.Comment: 381 authors, 6 pages, 4 figures. Published in Phys. Rev. Lett.
(http://link.aps.org/doi/10.1103/PhysRevLett.107.172301). v3 has minor
changes to match published version
(http://www.phenix.bnl.gov/phenix/WWW/info/pp1/128/PhysRevLett.107.172301)
Plain text data tables for points plotted in figures are publicly available
at http://www.phenix.bnl.gov/phenix/WWW/info/data/ppg128_data.htm
Effects of human land use on the terrestrial and aquatic sources of fluvial organic matter in a temperate river basin (The Meuse River, Belgium)
Etude toxicogénomique de nanovecteurs de silice mésoporeuse : relation entre décoration et toxicité
Nanoparticles (NPs) capable of transporting and releasing therapeutic agents to target tissues constitute one of the most exciting areas in nanomedicine, especially magnetic mesoporous silica nanoparticles (M-MSN). M-MSNs may be addressed to tumors thanks to their magnetism and can act as drug carriers thanks to their high specific surface area. Nevertheless, the safety of these NPs with decorations, conferring them specific properties, must be assessed in order to avoid harmful effects on healthy tissues, in particular on the liver, the organ of xenobiotics metabolism.The goal of this thesis was therefore to evaluate the potential toxicity of M-MSN either pristine, or coated with polyethylene glycol (PEG), or surrounded by a lipid bilayer of 1,2-dimyristoyl-sn-glycero-3- Phosphocholine (DMPC). To this end, the human hepatic cell model HepaRG was chosen to realize in vitro toxicity testing and to elucidate the intracellular mode of action of these various NPs.The physico-chemical properties of pristine and covered M-MSNs were measured using different techniques such as dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). NPs toxicity was first evaluated by viability testing and real-time cell impedance analysis (xCELLigence).Gene expression profiles were then performed through very high density oligo microarrays (8x60k, Agilent) to evaluate, in a dose- and time-dependent manner, the toxicity of these NPs. In addition, the use of an original methodology for comparative analysis of large biological data allowed us to demonstrate the molecular mechanisms triggered by the NPs in the hepatocytes. We were able to determine the dose not triggering any toxicity as well as the dose inducing a slight transient toxicity after 24h. We thus defined this latter value as a threshold of biocompatibility with HepaRG cells. We also showed by TEM a slower uptake of PEGylated NPs by cells as well as their delayed effects on the transcriptome compared to the pristine and DMPC NPs. Nevertheless, a dose of 80 ÎŒg/cmÂČ of pristine or covered M-MSNs triggers the chain of events of the hepatic cholestasis AOP (Adverse Outcome Pathway). This result demonstrates that this methodology is suitable for predictive toxicology by analysis of cellular biological responses after exposure to exogenous substances.Furthermore, NPs tend to be covered with proteins in the presence of serum (corona). Cell impedance analysis shows that M-MSNs surrounded by human or bovine serum proteins coronas do not trigger the same toxicity on human cells. This result raises the problem of a potential overestimation of NPs toxicity to human cells in in vitro testing by using fetal bovine serum in culture media.We undertook a dynamic analysis (between 30 s and 7 days) of the corona formation by tandem mass spectrometry has highlighted three groups of protein with distinct behaviors. The first cluster contains some abundant proteins that desorb over time, the second cluster comprises some protein families such as apolipoproteins, and the third cluster contains late enrichment proteins attracted by other proteins already present in the corona. A dynamic network of protein-protein interactions inside the corona, namely the interactome, was built from the data. This work opens the way to a possible control of the corona in order to provide the nanocarriers with stealth properties allowing them to reach target organs without being opsonized.These techniques used during this thesis and based on analyses of biological big data might be part of the future standards on nanosafety evaluation.Les nanoparticules (NPs) concentrent beaucoup dâespoir en nanomĂ©decine, en particulier les nanoparticules magnĂ©tiques de silice mĂ©soporeuse (M-MSN) qui pourraient permettre des avancĂ©es en thĂ©ranostic. NĂ©anmoins lâinnocuitĂ© de ces NPs recouvertes de dĂ©corations leur confĂ©rant des propriĂ©tĂ©s spĂ©cifiques, doit ĂȘtre dĂ©montrĂ©e afin dâĂ©viter des effets nĂ©fastes sur les tissus sains, notamment sur le foie, lâorgane de transformation des xĂ©nobiotiques. Lâobjectif de cette thĂšse Ă©tait donc dâĂ©valuer la toxicitĂ© potentielle de M-MSN soit natives, soit recouvertes de polyĂ©thylĂšne glycol (PEG), soit entourĂ©es dâune bicouche lipidique de 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Pour ce faire un modĂšle de cellules humaines hĂ©patiques (HepaRG) a Ă©tĂ© choisi pour effectuer des tests de toxicitĂ© in vitro et pour Ă©lucider le mode dâaction intracellulaire de ces diffĂ©rentes NPs.Les caractĂ©ristiques physico-chimiques des M-MSNs natives et dĂ©corĂ©es ont Ă©tĂ© mesurĂ©es par diffĂ©rentes techniques comme la diffusion dynamique de la lumiĂšre (DLS), la microscopie Ă©lectronique Ă transmission (TEM) et la microscopie Ă force atomique (AFM). La toxicitĂ© des NPs a Ă©tĂ© Ă©valuĂ©e tout dâabord par des tests de viabilitĂ© et par impĂ©dance cellulaire en temps rĂ©el (xCELLigence).LâĂ©tude des profils dâexpression gĂ©nique sur des oligo microarrays Ă trĂšs haute densitĂ© (8x60k sondes, Agilent) a ensuite permis dâĂ©valuer, de façon dose- et temps-dĂ©pendante, la toxicitĂ© de ces NPs. De plus lâutilisation dâune mĂ©thodologie originale dâanalyse comparative de donnĂ©es massives nous a permis de mettre en Ă©vidence les mĂ©canismes molĂ©culaires dĂ©clenchĂ©s par les NPs dans les hĂ©patocytes. Nous avons dĂ©terminĂ© des doses nâinduisant aucune toxicitĂ© ou une lĂ©gĂšre toxicitĂ© transitoire aprĂšs 24h, soit une valeur seuil de biocompatibilitĂ© avec les cellules HepaRG. Nous avons Ă©galement montrĂ© par TEM le ralentissement de lâinternalisation des NPs lorsquâelles sont PEGylĂ©es ainsi que leurs effets transcriptomiques diffĂ©rĂ©s par rapport aux NPs natives et lipidiques. NĂ©anmoins, une dose de 80 ”g/cmÂČ de M-MSNs, natives ou dĂ©corĂ©es, dĂ©clenche lâenchaĂźnement des Ă©vĂšnements de lâAOP (Adverse Outcome Pathway) de la cholestase hĂ©patique. Ce rĂ©sultat dĂ©montre que cette mĂ©thodologie est adaptĂ©e Ă la toxicologie prĂ©dictive par analyse des rĂ©ponses biologiques cellulaires aprĂšs exposition Ă des substances exogĂšnes.Par ailleurs, les NPs ont tendance Ă se recouvrir de protĂ©ines (corona) en prĂ©sence de sĂ©rum humain. Lâanalyse par impĂ©dance cellulaire montre que des M-MSNs entourĂ©es dâune corona de protĂ©ines sĂ©riques humaines ou bovines ne provoquent pas la mĂȘme toxicitĂ© sur des cellules humaines. Ce rĂ©sultat pose la problĂ©matique d'une potentielle surestimation de la toxicitĂ© des nanoparticules lors dâessais in vitro, utilisant classiquement du sĂ©rum de veau dans les milieux de cultures.Nous avons entrepris lâĂ©tude de la dynamique de la corona (entre 30s et 7 jours) par spectromĂ©trie de masse en tandem. Cette analyse a mis en lumiĂšre trois types de comportements protĂ©iques. Le premier cluster contient des protĂ©ines abondantes qui se dĂ©sorbent au cours du temps, le second cluster est composĂ© de protĂ©ines qui sâenrichissent progressivement et issues de mĂȘmes familles protĂ©iques comme les apolipoprotĂ©ines, et le troisiĂšme cluster contient des protĂ©ines Ă enrichissement tardif dans la corona, attirĂ©es par leur affinitĂ© pour des protĂ©ines dĂ©jĂ prĂ©sentes. Un rĂ©seau dynamique dâinteractions protĂ©ines-protĂ©ines, ou intĂ©ractome, a pu ĂȘtre cartographiĂ© au sein de la corona. Ces travaux posent les bases dâun possible contrĂŽle des protĂ©ines de la corona afin de confĂ©rer aux nanovecteurs des propriĂ©tĂ©s de furtivitĂ© leur permettant dâatteindre des organes cibles sans ĂȘtre opsonisĂ©s. Les techniques utilisĂ©es au cours de ce travail, basĂ©es sur les analyses de quantitĂ©s massives de donnĂ©es biologiques, pourraient faire partie de futurs standards dâĂ©valuation de la nanosĂ©curitĂ©
Ex vivo assessment of testicular toxicity induced by carbendazim and iprodione, alone or in a mixture
International audienc
Toxicogenomic study of mesoporous silica nanocarriers : relationship between surface decoration and toxicity
Les nanoparticules (NPs) concentrent beaucoup dâespoir en nanomĂ©decine, en particulier les nanoparticules magnĂ©tiques de silice mĂ©soporeuse (M-MSN) qui pourraient permettre des avancĂ©es en thĂ©ranostic. NĂ©anmoins lâinnocuitĂ© de ces NPs recouvertes de dĂ©corations leur confĂ©rant des propriĂ©tĂ©s spĂ©cifiques, doit ĂȘtre dĂ©montrĂ©e afin dâĂ©viter des effets nĂ©fastes sur les tissus sains, notamment sur le foie, lâorgane de transformation des xĂ©nobiotiques. Lâobjectif de cette thĂšse Ă©tait donc dâĂ©valuer la toxicitĂ© potentielle de M-MSN soit natives, soit recouvertes de polyĂ©thylĂšne glycol (PEG), soit entourĂ©es dâune bicouche lipidique de 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Pour ce faire un modĂšle de cellules humaines hĂ©patiques (HepaRG) a Ă©tĂ© choisi pour effectuer des tests de toxicitĂ© in vitro et pour Ă©lucider le mode dâaction intracellulaire de ces diffĂ©rentes NPs.Les caractĂ©ristiques physico-chimiques des M-MSNs natives et dĂ©corĂ©es ont Ă©tĂ© mesurĂ©es par diffĂ©rentes techniques comme la diffusion dynamique de la lumiĂšre (DLS), la microscopie Ă©lectronique Ă transmission (TEM) et la microscopie Ă force atomique (AFM). La toxicitĂ© des NPs a Ă©tĂ© Ă©valuĂ©e tout dâabord par des tests de viabilitĂ© et par impĂ©dance cellulaire en temps rĂ©el (xCELLigence).LâĂ©tude des profils dâexpression gĂ©nique sur des oligo microarrays Ă trĂšs haute densitĂ© (8x60k sondes, Agilent) a ensuite permis dâĂ©valuer, de façon dose- et temps-dĂ©pendante, la toxicitĂ© de ces NPs. De plus lâutilisation dâune mĂ©thodologie originale dâanalyse comparative de donnĂ©es massives nous a permis de mettre en Ă©vidence les mĂ©canismes molĂ©culaires dĂ©clenchĂ©s par les NPs dans les hĂ©patocytes. Nous avons dĂ©terminĂ© des doses nâinduisant aucune toxicitĂ© ou une lĂ©gĂšre toxicitĂ© transitoire aprĂšs 24h, soit une valeur seuil de biocompatibilitĂ© avec les cellules HepaRG. Nous avons Ă©galement montrĂ© par TEM le ralentissement de lâinternalisation des NPs lorsquâelles sont PEGylĂ©es ainsi que leurs effets transcriptomiques diffĂ©rĂ©s par rapport aux NPs natives et lipidiques. NĂ©anmoins, une dose de 80 ”g/cmÂČ de M-MSNs, natives ou dĂ©corĂ©es, dĂ©clenche lâenchaĂźnement des Ă©vĂšnements de lâAOP (Adverse Outcome Pathway) de la cholestase hĂ©patique. Ce rĂ©sultat dĂ©montre que cette mĂ©thodologie est adaptĂ©e Ă la toxicologie prĂ©dictive par analyse des rĂ©ponses biologiques cellulaires aprĂšs exposition Ă des substances exogĂšnes.Par ailleurs, les NPs ont tendance Ă se recouvrir de protĂ©ines (corona) en prĂ©sence de sĂ©rum humain. Lâanalyse par impĂ©dance cellulaire montre que des M-MSNs entourĂ©es dâune corona de protĂ©ines sĂ©riques humaines ou bovines ne provoquent pas la mĂȘme toxicitĂ© sur des cellules humaines. Ce rĂ©sultat pose la problĂ©matique d'une potentielle surestimation de la toxicitĂ© des nanoparticules lors dâessais in vitro, utilisant classiquement du sĂ©rum de veau dans les milieux de cultures.Nous avons entrepris lâĂ©tude de la dynamique de la corona (entre 30s et 7 jours) par spectromĂ©trie de masse en tandem. Cette analyse a mis en lumiĂšre trois types de comportements protĂ©iques. Le premier cluster contient des protĂ©ines abondantes qui se dĂ©sorbent au cours du temps, le second cluster est composĂ© de protĂ©ines qui sâenrichissent progressivement et issues de mĂȘmes familles protĂ©iques comme les apolipoprotĂ©ines, et le troisiĂšme cluster contient des protĂ©ines Ă enrichissement tardif dans la corona, attirĂ©es par leur affinitĂ© pour des protĂ©ines dĂ©jĂ prĂ©sentes. Un rĂ©seau dynamique dâinteractions protĂ©ines-protĂ©ines, ou intĂ©ractome, a pu ĂȘtre cartographiĂ© au sein de la corona. Ces travaux posent les bases dâun possible contrĂŽle des protĂ©ines de la corona afin de confĂ©rer aux nanovecteurs des propriĂ©tĂ©s de furtivitĂ© leur permettant dâatteindre des organes cibles sans ĂȘtre opsonisĂ©s. Les techniques utilisĂ©es au cours de ce travail, basĂ©es sur les analyses de quantitĂ©s massives de donnĂ©es biologiques, pourraient faire partie de futurs standards dâĂ©valuation de la nanosĂ©curitĂ©.Nanoparticles (NPs) capable of transporting and releasing therapeutic agents to target tissues constitute one of the most exciting areas in nanomedicine, especially magnetic mesoporous silica nanoparticles (M-MSN). M-MSNs may be addressed to tumors thanks to their magnetism and can act as drug carriers thanks to their high specific surface area. Nevertheless, the safety of these NPs with decorations, conferring them specific properties, must be assessed in order to avoid harmful effects on healthy tissues, in particular on the liver, the organ of xenobiotics metabolism.The goal of this thesis was therefore to evaluate the potential toxicity of M-MSN either pristine, or coated with polyethylene glycol (PEG), or surrounded by a lipid bilayer of 1,2-dimyristoyl-sn-glycero-3- Phosphocholine (DMPC). To this end, the human hepatic cell model HepaRG was chosen to realize in vitro toxicity testing and to elucidate the intracellular mode of action of these various NPs.The physico-chemical properties of pristine and covered M-MSNs were measured using different techniques such as dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). NPs toxicity was first evaluated by viability testing and real-time cell impedance analysis (xCELLigence).Gene expression profiles were then performed through very high density oligo microarrays (8x60k, Agilent) to evaluate, in a dose- and time-dependent manner, the toxicity of these NPs. In addition, the use of an original methodology for comparative analysis of large biological data allowed us to demonstrate the molecular mechanisms triggered by the NPs in the hepatocytes. We were able to determine the dose not triggering any toxicity as well as the dose inducing a slight transient toxicity after 24h. We thus defined this latter value as a threshold of biocompatibility with HepaRG cells. We also showed by TEM a slower uptake of PEGylated NPs by cells as well as their delayed effects on the transcriptome compared to the pristine and DMPC NPs. Nevertheless, a dose of 80 ÎŒg/cmÂČ of pristine or covered M-MSNs triggers the chain of events of the hepatic cholestasis AOP (Adverse Outcome Pathway). This result demonstrates that this methodology is suitable for predictive toxicology by analysis of cellular biological responses after exposure to exogenous substances.Furthermore, NPs tend to be covered with proteins in the presence of serum (corona). Cell impedance analysis shows that M-MSNs surrounded by human or bovine serum proteins coronas do not trigger the same toxicity on human cells. This result raises the problem of a potential overestimation of NPs toxicity to human cells in in vitro testing by using fetal bovine serum in culture media.We undertook a dynamic analysis (between 30 s and 7 days) of the corona formation by tandem mass spectrometry has highlighted three groups of protein with distinct behaviors. The first cluster contains some abundant proteins that desorb over time, the second cluster comprises some protein families such as apolipoproteins, and the third cluster contains late enrichment proteins attracted by other proteins already present in the corona. A dynamic network of protein-protein interactions inside the corona, namely the interactome, was built from the data. This work opens the way to a possible control of the corona in order to provide the nanocarriers with stealth properties allowing them to reach target organs without being opsonized.These techniques used during this thesis and based on analyses of biological big data might be part of the future standards on nanosafety evaluation
Ex vivo assessment of testicular toxicity induced by carbendazim and iprodione, alone or in a mixture
International audienc
Discovery of a large set of SNP and SSR genetic markers by high-throughput sequencing of pepper (Capsicum annuum)
Genetic markers based on single nucleotide polymorphisms (SNPs) are in increasing demand for genome mapping and fingerprinting of breeding populations in crop plants. Recent advances in high-throughput sequencing provide the opportunity for whole-genome resequencing and identification of allelic variants by mapping the reads to a reference genome. However, for many species, such as pepper (Capsicum annuum), a reference genome sequence is not yet available. To this end, we sequenced the C. annuum cv. "Yolo Wonder" transcriptome using Roche 454 pyrosequencing and assembled de novo 23,748 isotigs and 60,370 singletons. Mapping of 10,886,425 reads obtained by the Illumina GA II sequencing of C. annuum cv. "Criollo de Morclos 334" to the "Yolo Wonder" transcriptome allowed for SNP identification. By setting a threshold value that allows selecting reliable SNPs with minimal loss of information, 11,849 reliable SNPs spread across 5919 isotigs were identified. In addition, 853 single sequence repeats were obtained. This information has been made available online
High-throughput, quantitative assessment of the effects of low-dose silica nanoparticles on lung cells: grasping complex toxicity with a great depth of field
Biocompatibility assessment of functionalized magnetic mesoporous silica nanoparticles in human HepaRG cells
Magnetic mesoporous silica nanoparticles (M-MSNs) are a promising class of nanoparticles for drug delivery. However, a deep understanding of the toxicological mechanisms of action of these nanocarriers is essential, especially in the liver. The potential toxicity on HepaRG cells of pristine, pegylated (PEG), and lipid (DMPC) M-MSNs were compared.
Based on MTT assay and real-time cell impedance, none of these NPs presented an extensive toxicity on hepatic cells. However, we observed by transmission electron microscopy (TEM) that the DMPC and pristine M-MSNs were greatly internalized. In comparison, PEG M-MSNs showed a slower cellular uptake. Whole gene expression profiling revealed the M-MSNs molecular modes of action in a time-and dose-dependent manner. The lowest dose tested (1.6 ”g/cmÂČ) induced no molecular effect and was defined as âNo Observed Transcriptional Effect levelâ. The dose 16 ”g/cmÂČ revealed nascent but transient effects. At the highest dose (80 ”g/cmÂČ), adverse effects have clearly arisen and increased over time. The limit of biocompatibility for HepaRG cells could be set at 16 ”g/cmÂČ for these NPs.
Thanks to a comparative pathway-driven analysis, we highlighted the sequence of events that leads to the disruption of hepatobiliary system, elicited by the three types of M-MSNs, at the highest dose. The Adverse Outcome Pathway of hepatic cholestasis was implicated. Toxicogenomics applied to cell cultures is an effective tool to characterize and compare the modes of action of many substances. We propose this strategy as an asset for upstream selection of the safest nanocarriers in the framework of regulation for nanobiosafet
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