245 research outputs found

    On the Organization of a Drug Discovery Platform

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    Some of the most exciting parts of work in the pharmaceutical industry are the steps leading up to drug discovery. This process can be oversimplified by describing it as a screening campaign involving the systematic testing of many compounds in a test relevant to a given pathology. This naĂŻve description takes place without taking into consideration the numerous key steps that led up to the screening or the steps that might follow. The present chapter describes this whole process as it was conducted in our company during our early drug discovery activities. First, the purpose of the procedures is described and rationalized. Next follows a series of mostly published examples from our own work illustrating the various steps of the process from cloning to biophysics, including expression systems and membrane-bound protein purifications. We believe that what is described here presents an example of how pharmaceutical industry research can organize its platform(s) when the goal is to find and qualify a new preclinical drug candidate using cutting-edge technologies and a lot of hard work

    PVP2008-61232 ILLUSTRATION OF THE WPS BENEFIT THROUGH BATMAN TEST SERIES: TESTS ON LARGE SPECIMENS UNDER WPS LOADING CONFIGURATIONS

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    ABSTRACT A study combining modelling and a series of experiments on large specimens submitted to a thermal shock or isothermal cooling has been performed in CEA-Saclay in order to show the WPS benefit on large scale specimen. The test series, named BATMAN, was made on 18MND5 ferritic steel bars, containing a short or large fatigue pre-crack. For the two performed tests (fast thermal shock creating a gradient across the thickness of the bar or for the gradual uniform cooling), the effect of "Warm Pre-Stressing" was confirmed. In both cases, no propagation was observed during the thermal transient. Fracture occurred under low temperature conditions, at the end of the test when the tensile load was increased. The failure loads then recorded were substantially higher than during prestressing. To illustrate the benefit of the WPS effect, numerical interpretations were performed using either global approach or local approach criteria. The capability of models to predict the WPS effect was clearly shown. INTRODUCTION A large amount of work was performed on ferritic steels to demonstrate the benefit of the Warm Pre-Stressing (WPS) effect. Mainly on small specimens and in the frame of experimental and theoretical studies, the objectives were to show the enhancement of the cleavage fracture toughness at low temperature following the application of a preloading at higher temperature (which exceeds the fracture toughness of the virgin material at low temperature)

    Functional invalidation of the autotaxin gene by a single amino acid mutation in mouse is lethal

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    AbstractAutotaxin is a member of the phosphodiesterase family of enzymes, (NPP2). It is an important secreted protein found in conditioned medium from adipocytes. It also has a putative role in the metastatic process. Based on these observation, further validation of this potential target was necessary, apart from the classical biochemical ones. The construction of a knock out mouse strain for ATX was started. In this paper, we report the generation of a mouse line displaying an inactivated ATX gene product. The KO line was designed in order to generate a functional inactivation of the protein. In this respect, the threonine residue T210 was replaced by an alanine (T210A) leading to a catalytically inactive enzyme. If the experimental work was straight forward, we disappointedly discovered at the final stage that the breeding of heterozygous animals, ATX −/+, led to the generation of a Mendelian repartition of wild-type and heterozygous, but no homozygous were found, strongly suggesting that the ATX deletion is lethal at an early stage of the development. This was confirmed by statistical analysis. Although other reported the same lethality for attempted ATX−/− mice generation [van Meeteren, L.A., Ruurs, P., Stortelers, C., Bouwman, P., van Rooijen, M.A., Pradùre, J.P., Pettit, T.R., Wakelam, M.J.O., Saulnier-Blache, J.S., Mummery, C.L., Moolenar, W.H. and Jonkers, J. (2006) Autotaxin, a secreted lysophospholipase D, is essential for blood vessel formation during development, Mol. Cell. Biol. 26, 5015–5022; Tanaka, M., Okudaira, S., Kishi, Y., Ohkawa, R., Isei, S., Ota, M., Noji, S., Yatomi, Y., Aoki, J., and Arai, H. (2006) Autotaxin stabilizes blood vessels and is required for embryonic vasculature by producing lysophosphatidic acid, J. Biol. Chem. 281, 25822–25830], they used more drastic multiple exon deletions in the ATX gene, while we chose a single point mutation. To our knowledge, the present work is the first showing such a lethality in any gene after a point mutation in an enzyme catalytic site

    CETOBaC – Centre d’études turques, ottomanes, balkaniques et centrasiatiques

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    Marc Aymes, chargĂ© de recherche au CNRSMaroussia Ferry, doctorante Ă  l’EHESS/INEDHayri Göksin Özkoray, doctorant Ă  l’EPHE SĂ©minaire interdisciplinaire d’études turques (SIDET) L’innervation des sciences sociales par les « aires culturelles », et rĂ©ciproquement, demeure problĂ©matique. Elle est, en tant que principe de formation, la prĂ©occupation essentielle de ce sĂ©minaire, qui a pour objectif d’en favoriser la mise en Ɠuvre, Ă  l’échelle de ce qu’il est convenu d’appeler les « études turques »..

    CETOBaC – Centre d’études turques, ottomanes, balkaniques et centrasiatiques

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    Marc Aymes, chargĂ© de recherche au CNRSMaroussia Ferry, doctorante Ă  l’EHESS/INEDHayri Göksin Özkoray, doctorant Ă  l’EPHE SĂ©minaire interdisciplinaire d’études turques (SIDET) L’innervation des sciences sociales par les « aires culturelles », et rĂ©ciproquement, demeure problĂ©matique. Elle est, en tant que principe de formation, la prĂ©occupation essentielle de ce sĂ©minaire, qui a pour objectif d’en favoriser la mise en Ɠuvre, Ă  l’échelle de ce qu’il est convenu d’appeler les « études turques »..

    Soil variation response is mediated by growth trajectories rather than functional traits in a widespread pioneer Neotropical tree

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    1. Trait-environment relationships have been described at the community level across tree species. However, whether interspecific trait-environment relationships are consistent at the intraspecific level is yet unknown. Moreover, we do not know how consistent is the response between organ vs. whole-tree level. 2. We examined phenotypic variability for 16 functional leaf (dimensions, nutrient, chlorophyll) and wood traits (density) across two soil types, Ferralitic Soil (FS) vs. White Sands (WS), on two sites for 70 adult trees of Cecropia obtusa Trécul (Urticaceae) in French Guiana. Cecropia is a widespread pioneer Neotropical genus that generally dominates early successional forest stages. To understand how soil types impact resource use through the processes of growth and branching, we examined the architectural development with a retrospective analysis of growth trajectories. We expect soil types to affect both, functional traits in relation to resource acquisition strategy as already described at the interspecific level, and growth strategies due to resource limitations with reduced growth on poor soils. 3. Functional traits were not involved in the soil response, as only two traits -leaf residual water content and K content-showed significant differences across soil types. Soil effects were stronger on growth trajectories, with WS trees having the slowest growth trajectories and less numerous branches across their lifespan. 4. The analysis of growth trajectories based on architectural analysis improved our ability to characterise the response of trees with soil types. The intraspecific variability is higher for growth trajectories than functional traits for  C. obtusa, revealing the complementarity of the architectural approach with the functional approach to gain insights on the way trees manage their resources over their lifetime. Soil-related responses of Cecropia functional traits are not the same as those at the interspecific level, suggesting that the effects of the acting ecological processes are different between the two levels. Apart from soil differences, much variation was found across sites, which calls for further investigation of the factors shaping growth trajectories in tropical forests

    Large trees drive forest aboveground biomass variation in moist lowland forests accross the tropics

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    peer reviewedaudience: researcher, professional, studentAim Large trees (d.b.h. 70 cm) store large amounts of biomass. Several studies suggest that large trees may be vulnerable to changing climate, potentially leading to declining forest biomass storage. Here we determine the importance of large trees for tropical forest biomass storage and explore which intrinsic (species trait) and extrinsic (environment) variables are associated with the density of large trees and forest biomass at continental and pan-tropical scales. Location Pan-tropical. Methods Aboveground biomass (AGB) was calculated for 120 intact lowland moist forest locations. Linear regression was used to calculate variation in AGB explained by the density of large trees. Akaike information criterion weights (AICcwi) were used to calculate averaged correlation coefficients for all possible multiple regression models between AGB/density of large trees and environmental and species trait variables correcting for spatial autocorrelation. Results Density of large trees explained c. 70% of the variation in pan-tropical AGB and was also responsible for significantly lower AGB in Neotropical [287.8 (mean) 105.0 (SD) Mg ha-1] versus Palaeotropical forests (Africa 418.3 91.8 Mg ha-1; Asia 393.3 109.3 Mg ha-1). Pan-tropical variation in density of large trees and AGB was associated with soil coarseness (negative), soil fertility (positive), community wood density (positive) and dominance of wind dispersed species (positive), temperature in the coldest month (negative), temperature in the warmest month (negative) and rainfall in the wettest month (positive), but results were not always consistent among continents. Main conclusions Density of large trees and AGB were significantly associated with climatic variables, indicating that climate change will affect tropical forest biomass storage. Species trait composition will interact with these future biomass changes as they are also affected by a warmer climate. Given the importance of large trees for variation in AGB across the tropics, and their sensitivity to climate change, we emphasize the need for in-depth analyses of the community dynamics of large trees
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