Showing papers by "Paul Sabatier University published in 2002"
TL;DR: Small nucleolar RNAs represent an abundant, evolutionarily ancient group of noncoding RNAs which possess impressively diverse functions ranging from 2'-O-methylation and pseudouridylation of various classes of RNAs, through nucleolytic processing of rRNAs to the synthesis of telomeric DNA.
789 citations
TL;DR: Recent characterization of homologs of eukaryotic modification guide snoRNAs in Archaea reveals the ancient origin of these non-coding RNA families and offers new perspectives as to their range of function.
641 citations
TL;DR: In this paper, the authors collected from the Rainbow vent field (36°14′N) on the Mid-Atlantic Ridge (MAR) during the 1997 diving FLORES cruise, which is composed of ∼10 black smokers emitting acidic fluids at 365 °C.
629 citations
TL;DR: ERP differences revealed that the magnitude of this repetition effect was smaller for negative and inverted than upright faces at 0-lag but not at 1-lag condition, suggesting face encoding and recognition processes were affected by inversion and contrast-reversal differently.
517 citations
TL;DR: The argumentation framework proposed by Dung is refined by taking into account preference relations between arguments in order to integrate two complementary points of view on the concept of acceptability, which refines previous works by Prakken and Sartor.
Abstract: Argumentation is a reasoning model based on the construction of arguments and counter-arguments (or defeaters) followed by the selection of the most acceptable of them. In this paper, we refine the argumentation framework proposed by Dung by taking into account preference relations between arguments in order to integrate two complementary points of view on the concept of acceptability: acceptability based on the existence of direct counter-arguments and acceptability based on the existence of defenders. An argument is thus acceptable if it is preferred to its direct defeaters or if it is defended against its defeaters. This also refines previous works by Prakken and Sartor, by associating with each argument a notion of strength, while these authors embed preferences in the definition of the defeat relation. We propose a revised proof theory in terms of AND/OR trees, verifying if a given argument is acceptable, which better reflects the dialectical form of argumentation.
481 citations
TL;DR: The results provide strong support for the idea that the Cajal body, this mysterious nuclear organelle, provides the cellular locale for post‐transcriptional modification of spliceosomal snRNAs.
Abstract: Cajal (coiled) bodies are conserved subnuclear organelles that are present in the nucleoplasm of both animal and plant cells. Although Cajal bodies were first described nearly 100 years ago, their function has remained largely speculative. Here, we describe a novel class of human small nuclear RNAs that localize specifically to Cajal bodies. The small Cajal body- specific RNAs (scaRNAs) are predicted or have already been demonstrated to function as guide RNAs in site-specific synthesis of 2′-O-ribose-methylated nucleotides and pseudouridines in the RNA polymerase II-transcribed U1, U2, U4 and U5 spliceosomal small nuclear RNAs (snRNAs). Our results provide strong support for the idea that the Cajal body, this mysterious nuclear organelle, provides the cellular locale for post-transcriptional modification of spliceosomal snRNAs.
465 citations
TL;DR: The chemical evolution of the surface of the Earth is controlled by the interaction of rainwaters, the atmosphere and the continental crust as discussed by the authors, which is the main reason why the knowledge of the parameters that control chemical denudation on Earth is of crucial importance.
432 citations
TL;DR: In this paper, experiments were carried out to investigate the sorption of the complete lanthanide series (Ln or rare earth elements, REE) on a kaolinite and an a Na-montmorillonite at 22°C over a wide range of pH (3-9).
422 citations
TL;DR: Immuno‐fluorescence and biochemical evidences are presented showing that OPA1 resides in the mitochondria where it is imported through its highly basic amino‐terminal extension.
408 citations
TL;DR: A review of the literature on three recent prodrugs of 5-FU, i.e., capecitabine, UFT (ftorafur [FTO] plus uracil), and S-1 (FTO plus 5-chloro-2,4-dihydroxypyridine plus potassium oxonate), focusing on antitumor activity and toxicity are presented.
Abstract: Although 5-fluorouracil (5-FU) was first introduced in 1957, it remains an essential part of the treatment of a wide range of solid tumors. 5-FU has antitumor activity against epithelial malignancies arising in the gastrointestinal tract and breast as well as the head and neck, with single-agent response rates of only 10%-30%. Although 5-FU is still the most widely prescribed agent for the treatment of colorectal cancer, less than one-third of patients achieve objective responses. Recent research has focused on the biomodulation of 5-FU to improve the cytotoxicity and therapeutic effectiveness of this drug in the treatment of advanced disease. As all the anticancer agents, 5-FU leads to several toxicities. The toxicity profile of 5-FU is schedule dependent. Myelotoxicity is the major toxic effect in patients receiving bolus doses. Hand-foot syndrome (palmar-plantar erythrodysesthesia), stomatitis, and neuro- and cardiotoxicities are associated with continuous infusions. Other adverse effects associated with both bolus-dose and continuous-infusion regimens include nausea and vomiting, diarrhea, alopecia, and dermatitis. All these reasons explain the need for more effective and less toxic fluoropyrimidines. In the first part of this review, we briefly present the metabolic pathways of 5-FU responsible for the efficacy and toxicity of this drug. This knowledge is also necessary to understand the target(s) of biomodulation. The second part is devoted to a review of the literature on three recent prodrugs of 5-FU, i.e., capecitabine, UFT (ftorafur [FTO] plus uracil), and S-1 (FTO plus 5-chloro-2,4-dihydroxypyridine plus potassium oxonate). The pharmacological principles that have influenced the development of these new drugs and our current knowledge of the clinical pharmacology of these new agents, focusing on antitumor activity and toxicity, are presented. The literature was analyzed until March 2002. This review is intended to be as exhaustive as possible since it was conceived as a work tool for readers wanting to go further.
365 citations
TL;DR: Significant progress has been made in the diverse aspects of the biological field, in particular, in relation to the role of dietary ligands on aluminium gastrointestinal absorption, excretion and tissue distribution and some progress has also been made on the chemical side relative to computer-aided speciation applications to gastrointestinal and blood plasma conditions.
TL;DR: In this article, a reaction mechanism involving hydroxyl radicals, HSO4-and undissociated H2SO4 is proposed, where electrogenerated hydroxym radicals at the B-doped synthetic diamond electrodes (BDD) anode react with HSO 4 and H2 SO 4 giving peroxodisulfate.
TL;DR: In this article, abranched fragments (200-400 µm) of a large, chemically homogeneous, and non-metamict Brazilian monazite crystal, characterised by a concordant U-Pb ages of 474 +/- 1 Ma (208Pb/206Pb = 19.5), were hydrothermally treated at varying temperatures with solutions of different compositions.
TL;DR: A correlation between aqueous and surface reactions stability constants allows the generation for all carbonates of a model describing their dissolution/precipitation kinetics, including the effect of various ligands, provided that rate constants and their activation volumes for water exchange around Me(II)-ligand dissolved complexes are available.
Abstract: A surface complexation model (SCM) for divalent metal carbonates (Ca, Mg, Sr, Ba, Mn, Fe, Co, Ni, Zn, Cd, and Pb) is developed based on new electrophoretic measurements and correlation between aqueous and surface reactions stability constants. This SCM postulates the formation of the following surface species: >CO3H0, >CO3-, >CO3Me+, >MeOH0, >MeO-, >MeOH2+, >MeHCO30, and MeCO3- within the framework of a constant capacitance of the electric double layer. It can be used to describe the surface-controlled dissolution kinetics of divalent metal carbonates and allows determination of the order of dissolution reactions with respect to rate-controlling protonated carbonate surface groups in acid solutions (>CO3H0) and hydrated metal groups (>MeOH2+) in neutral to alkaline solutions. The reaction order with respect to protonated carbonate groups increases from 2 for MnCO3 and ZnCO3 to 4 for NiCO3, whereas for hydrated surface metals, it augments from 2 for ZnCO3 to approximately 4 for MnCO3 and NiCO3. The dissolution rates at 5 < or = pH < or = 8 increase in the order Ni < Mg < Co < Fe < Mn < Zn < Cd < Sr < or = Ca approximately = Ba approximately = Pb and correlate nicely with water exchange rates from the aqueous solution into the hydration sphere of the corresponding dissolved cations. Such a correlation allows the generation for all carbonates of a model describing their dissolution/precipitation kinetics, including the effect of various ligands, provided that rate constants and their activation volumes for water exchange around Me(II)-ligand dissolved complexes are available.
TL;DR: By increasing the lipid concentration, increasing the number of freeze-thaw cycles and enhancing the interactions of the enzyme with the liposome lipid surface more than 40% of the initial total activity can be encapsulated.
Abstract: Background
We investigated the encapsulation mechanism of enzymes into liposomes. The existing protocols to achieve high encapsulation efficiencies are basically optimized for chemically stable molecules. Enzymes, however, are fragile and encapsulation requires in addition the preservation of their functionality. Using acetylcholinesterase as a model, we found that most protocols lead to a rapid denaturation of the enzyme with loss in the functionality and therefore inappropriate for such an application. The most appropriate method is based on lipid film hydration but had a very low efficiency.
TL;DR: Experiments were run with seven dyes and a Desal 5DK membrane (cut-off, 150–300 g/mole) to study the effects of concentration, pH and salt on flux and retention.
Abstract: Experiments were run with seven dyes and a Desal 5DK membrane (cut-off, 150–300 g/mole). The effects of concentration, pH and salt on flux and retention were studied. The cut-off of the membrane explains that the retention of the relative high molecular weight dyes (as direct red 80 or direct yellow 8) is always almost 100%. For anionic dyes as acid orange 10 or acid red 4, the amphoteric nature of polyamide explains the lower retention at pH 3 than 6. This effect is more pronounced and reversed for basic blue 3, a cationic dye. The membrane is sensitive to fouling since most of the dyes are used for polyamide textile dying. Moreover, the presence of salt leads to a further decrease in flux.
TL;DR: The availability of diradicals that can be handled under standard laboratory conditions will lead to further insight into their chemical and physical properties, raising the likelihood of practical applications, especially in the field of molecular materials such as electrical conductors and ferromagnets.
Abstract: Singlet diradicals are usually not energy minima. As observed by femtosecond spectroscopy, they readily couple to form σ bonds. Substituent effects allow lifetimes to increase into the microsecond range. Taking advantage of the properties of hetero-elements, a diradical has been prepared that is indefinitely stable at room temperature. The availability of diradicals that can be handled under standard laboratory conditions will lead to further insight into their chemical and physical properties, raising the likelihood of practical applications, especially in the field of molecular materials such as electrical conductors and ferromagnets.
TL;DR: It is argued for the existence of a "universal" Mediator structurally conserved from yeast to man, based on an extensive analysis of sequence databases, and the implications for the physiological roles of metazoan MED subunits are examined.
TL;DR: It turns out that this nonparametric regression model with scalar response when the explanatory variables are curves combines advantages of easy implementation and good mathematical properties.
Abstract: The aim of this paper is to present a nonparametric regression model with scalar response when the explanatory variables are curves. In this context, the crucial problem of dimension reduction is overriden by the use of an implicit fractal dimension hypothesis. For such a functional nonparametric regression model we introduce and study both practical and theoretical aspects of some kernel type estimator. After a simulation study, it is shown how this procedure is well adapted to some spectrometric data set. Asymptotic results are described and in conclusion it turns out that this method combines advantages of easy implementation and good mathematical properties.
TL;DR: The natural history of self-assemblages in insect societies is reviewed and it is found that at least 18 different types of structure exist: bivouacs, bridges, curtains, droplets, escape droplet, festoons, fills, flanges, ladders, ovens, plugs, pulling chains, queen clusters, rafts, swarms, thermoregulatory clusters, tunnels, and walls.
Abstract: In insect societies, a number of very striking collective structures are formed by individuals linking themselves to one another. One such example is an army ant bivouac. These structures are termed self-assemblages and are part of a more general and important aspect of insect societies - intermediate-level parts - in which functional group-level adaptive structures are formed. These parts are, in a sense, the tissues and organs of complex insect societies. Here we review the natural history of self-assemblages in insect societies. We find that at least 18 different types of structure exist: bivouacs, bridges, curtains, droplets, escape droplets, festoons, fills, flanges, ladders, ovens, plugs, pulling chains, queen clusters, rafts, swarms, thermoregulatory clusters, tunnels, and walls. These self-assemblages are found in a variety of species of ants, bees, and wasps, but (as far as we are aware) not in termites. The function of these self-assemblages can be grouped under five broad categories which are not mutually exclusive: 1) defence, 2) pulling structures, 3) thermoregulation, 4) colony survival under inclement conditions, and 5) ease of passage when crossing an obstacle. The paucity of our knowledge concerning the factors that favour self-assemblage formation and the likely proximate mechanisms are highlighted.
TL;DR: Data indicate that Pks15/1 is involved in the elongation of p-hydroxybenzoic acid to give p-Hydroxyphenylalkanoates, which in turn are converted, presumably by the PpsA-E synthase, to phenolphthiocerol derivatives.
TL;DR: In this article, a process based on simple and environmentally compatible operations, aimed to the treatment and recycling of spent lithium-ion batteries, is reported, which is safe, economic, and recovers as much of the battery materials as possible.
TL;DR: This paper investigates preference-based acceptability, the basic idea is to accept undefeated arguments and also arguments that are preferred to their defeaters, and defines argumentation frameworks based on that preference- based acceptability.
Abstract: Argumentation is a promising approach to handle inconsistent knowledge bases, based on the justification of plausible conclusions by arguments. Because of inconsistency, however, arguments may be defeated by counterarguments (or defeaters). The problem is thus to select the most acceptable arguments. In this paper we investigate preference-based acceptability. The basic idea is to accept undefeated arguments and also arguments that are preferred to their defeaters. We say that these arguments defend themselves against their defeaters. We define argumentation frameworks based on that preference-based acceptability. Finally, we study associated inference relations for reasoning with inconsistent knowledge bases.
TL;DR: These findings demonstrate that very early stages of processing can be modified by top-down attentional influences across a range of ages and experimental paradigms, concordant with visual processing models showing very rapid and dispersed activation with feedback at early cortical levels.
TL;DR: In this paper, a model was proposed to describe cross-flow filtration of colloidal particles and molecules, where surface and hydrodynamic interactions were used to predict the variation of the osmotic pressure and diffusion coefficient with the volume fraction of the suspension.
TL;DR: In this paper, Raspberry-like hybrid organic−inorganic materials consisting of spherical silica beads supporting smaller polystyrene particles were prepared through a heterophase polymerization process.
Abstract: Raspberrylike hybrid organic−inorganic materials consisting of spherical silica beads supporting smaller polystyrene particles were prepared through a heterophase polymerization process. In a first step, micrometer-sized silica particles were synthesized according to procedures inspired from the literature. In a second step, a poly(ethylene glycol) macromonomer was adsorbed on the surface of the silica beads. Finally, polymerization of styrene was achieved in water with a nonionic surfactant as an emulsifying agent and sodium persulfate as an initiator. Scanning and transmission electron microscopies show that the presence of the macromonomer on the surface of the silica particles is a determining parameter in order to get the raspberrylike morphology.
TL;DR: It is shown that the density averaged ansatz exhibits crucial, original (as compared to other SIC schemes) properties such as unitary robustness and applicability to semi-classical approaches.
Abstract: We present a simple density-averaged approach to the self-interaction-correction (SIC) methods of density functional theory. We discuss both formal properties and applications, considering particularly metal clusters as test cases. We show that the density averaged ansatz exhibits crucial, original (as compared to other SIC schemes) properties such as unitary robustness and applicability to semi-classical approaches. It is ideally suited to systems with well defined length and energy scales such as simple metal clusters.
TL;DR: It is shown, by an operator-theoretic proof, that the well-known Lie and Strang formulae are approximations of the exact solution of order 1 and 2 in time.
Abstract: In this paper, we consider the nonlinear Schrodinger equation $u_t+i\Delta u -F(u)=0$ in two dimensions. We show, by an operator-theoretic proof, that the well-known Lie and Strang formulae (which are splitting methods) are approximations of the exact solution of order 1 and 2 in time.
TL;DR: In this article, an in-line coagulation (without settling)/UF process has been studied to improve membrane performance and water quality for surface water treatment, where the extent of dissolved organic matter removal is controlled by the coagulations step.