Gene Expression Profiling of B Cell Chronic Lymphocytic Leukemia Reveals a Homogeneous Phenotype Related to Memory B Cells〉

B cell–derived chronic lymphocytic leukemia (B-CLL) represents a common malignancy whose cell derivation and pathogenesis are unknown. Recent studies have shown that >50% of CLLs display hypermutated immunoglobulin variable region (IgV) sequences and a more favorable prognosis, suggesting that they may represent a distinct subset of CLLs which have transited through germinal centers (GCs), the physiologic site of IgV hypermutation. To further investigate the phenotype of CLLs, their cellular derivation and their relationship to normal B cells, we have analyzed their gene expression profiles using oligonucleotide-based DNA chip microarrays representative of ∼12,000 genes. The results show that CLLs display a common and characteristic gene expression profile that is largely independent of their IgV genotype. Nevertheless, a restricted number of genes (<30) have been identified whose differential expression can distinguish IgV mutated versus unmutated cases and identify them in independent panels of cases. Comparison of CLL profiles with those of purified normal B cell subpopulations indicates that the common CLL profile is more related to memory B cells than to those derived from naive B cells, CD5+ B cells, and GC centroblasts and centrocytes. Finally, this analysis has identified a subset of genes specifically expressed by CLL cells of potential pathogenetic and clinical relevance

Towards IASI-New Generation (IASI-NG): impact of improved spectral resolution and radiometric noise on the retrieval of thermodynamic, chemistry and climate variables

Besides their strong contribution to weather forecast improvement through data assimilation, thermal infrared sounders onboard polar-orbiting platforms are now playing a key role for monitoring atmospheric composition changes. The Infrared Atmospheric Sounding Interferometer (IASI) instrument developed by the French space agency (CNES) and launched by Eumetsat onboard the Metop satellite series is providing essential inputs for weather forecasting and pollution/climate monitoring owing to its smart combination of large horizontal swath, good spectral resolution and high radiometric performance. EUMETSAT is currently preparing the next polar-orbiting program (EPS-SG) with the Metop-SG satellite series that should be launched around 2020. In this framework, CNES is studying the concept of a new instrument, the IASI-New Generation (IASI-NG), characterized by an improvement of both spectral and radiometric characteristics as compared to IASI, with three objectives: (i) continuity of the IASI/Metop series; (ii) improvement of vertical resolution; (iii) improvement of the accuracy and detection threshold for atmospheric and surface components. In this paper, we show that an improvement of spectral resolution and radiometric noise fulfill these objectives by leading to (i) a better vertical coverage in the lower part of the troposphere, thanks to the increase in spectral resolution; (ii) an increase in the accuracy of the retrieval of several thermodynamic, climate and chemistry variables, thanks to the improved signal-to-noise ratio as well as less interferences between the signatures of the absorbing species in the measured radiances. The detection limit of several atmospheric species is also improved. We conclude that IASI-NG has the potential for strongly benefiting the numerical weather prediction, chemistry and climate communities now connected through the European GMES/Copernicus initiative

Comparison study of the gas-phase oxidation of alkylbenzenes and alkylcyclohexanes

International audienceThe goal of this paper is to present new experimental results obtained during the study of the gas phase oxidation of ethyl-benzene, n-hexyl-benzene, ethyl-cyclohexane and n-butyl-cyclohexane which belongs to two molecule families present in diesel fuels: alkylbenzenes and alkylcyclohexanes. Experiments were carried out in a jet-stirred reactor over the temperature range 550–1100 K. The new results have been compared with existing literature data obtained for alkylbenzenes and alkylcyclohexanes with alkyl chains of different size to highlight the influence of the chain size on the reactivity. The comparison showed that both alkylcyclohexanes exhibit reactivity at both low-and high-temperatures such as cyclohexane and that the reactivity was similar whatever the size of the alkyl chain. For the three compared alkylbenzenes, important differences were observed in the reactivity at low-temperature: ethylbenzene started to react only above 750 K, while other compounds reacted from 550 K. The comparison also showed that alkylbenzenes were less reactive than their alkylcyclohexane homologs and that the production of aromatic compounds known to promote soot formation was also significantly larger for alkylbenzenes. This paper also presents the effect of the equivalence ratio and pressure on the reaction kinetics. In a general manner, a decrease of the fuel/air ratio significantly increased the reactivity and the carbon monoxide selectivity below 800 K, but decreased the selectivity of heavy oxygenated products, the atmospheric degradation of which can be a source of toxic oxygenated products. This decrease had a more limited effect on the reactivity at higher temperatures but disfavored the production of unburned species (oxygenated species like acetaldehyde and unsaturated hydrocarbons which are known to be soot precursors). A pressure increase from 1 to 10 bar enhanced the reactivity of all these hydrocarbons over the full studied temperature range, with a start of the reaction at lower temperatures. A larger production of toxic oxygenated products was observed with increasing pressures, while low pressures promoted the formation of soot precursors. Alkylbenzene results were generally well reproduced by simulations using literature models

Miocene Subsidence and Surface Uplift of Southernmost Tibet Induced by Indian Subduction Dynamics

International audienceThe Indus-Yarlung suture of southernmost Tibet marks the initial collisional zone, the ongoing India-Asia collision, and yet more than~30 million years after the onset of collision, a thick detrital sedimentary unit was deposited just north of the suture: the Kailas Formation. The mechanism permitting subsidence of the deep intracontinental Kailas basin in a compressional tectonic regime remains uncertain. We present new apatite (16-11 Ma) and zircon (24-19 Ma) fission track (AFT and ZFT) ages from the Gangdese batholith just north of the Kailas basin. ZFT analysis of modern-river sand from the northern Gangdese magmatic arc indicates an exhumation at 27.3 ± 1.3 Ma. Thermal modeling indicates that the batholith experienced reheating between 28 and 20 Ma, coeval with deposition in the Kailas basin (between 26 and 21 Ma), followed by overall rapid cooling between 20 and 17 Ma. We interpret this thermal history as a phase of regional Oligocene-Miocene sedimentary burial followed by exhumation. By modeling mantle dynamics in the geodynamic framework of the India-Asia collision, we show that transient dynamic topography over the relative southward folding of the Indian slab is consistent with burial and exhumation of the Gangdese magmatic arc during Oligocene-Miocene time. The northward migration of the Indian continent relative to its own stati onary slab created a wave of dynamic topography that caused subsidence in the overriding plate north of the Himalaya, followed by a phase of surface uplift since~27 Ma of the northern Gangdese magmatic arc. During latest Oligocene-early Miocene time, the dynamic deflection center was in the Kailas area, and it progressively relocated southward to its present position at the Ganges basin