University of Rouen

About: University of Rouen is a education organization based out in Rouen, France. It is known for research contribution in the topics: Population & Receptor. The organization has 7299 authors who have published 13209 publications receiving 313477 citations.

Candidate autoantigens identified by mass spectrometry in early rheumatoid arthritis are chaperones and citrullinated glycolytic enzymes

Abstract: Introduction The aim of our study was to identify new early rheumatoid arthritis (RA) autoantibodies.

On the selection of decision trees in Random Forests

Abstract: In this paper we present a study on the Random Forest (RF) family of ensemble methods. In a “classical” RF induction process a fixed number of randomized decision trees are inducted to form an ensemble. This kind of algorithm presents two main drawbacks : (i) the number of trees has to be fixed a priori (ii) the interpretability and analysis capacities offered by decision tree classifiers are lost due to the randomization principle. This kind of process in which trees are independently added to the ensemble, offers no guarantee that all those trees will cooperate effectively in the same committee. This statement rises two questions : are there any decision trees in a RF that provide the deterioration of ensemble performance? If so, is it possible to form a more accurate committee via removal of decision trees with poor performance? The answer to these questions is tackled as a classifier selection problem. We thus show that better subsets of decision trees can be obtained even using a sub-optimal classifier selection method. This proves that “classical” RF induction process, for which randomized trees are arbitrary added to the ensemble, is not the best approach to produce accurate RF classifiers. We also show the interest in designing RF by adding trees in a more dependent way than it is traditionally done in “classical” RF induction algorithms.

Structural requirements for Arabidopsis beta1,2-xylosyltransferase activity and targeting to the Golgi.

Abstract: Characterization of a beta1,2-xylosyltransferase from Arabidopsis thaliana (AtXylT) was carried out by expression in Sf9 insect cells using a baculovirus vector system. Serial deletions at both the N- and C-terminal ends proved that integrity of a large domain located between amino acid 31 and the C-terminal lumenal region is required for AtXylT activity expression. The influence of N-glycosylation on AtXylT activity has been evaluated using either tunicamycin or mutagenesis of potential N-glycosylation sites. AtXylT is glycosylated on two of its three potential N-glycosylation sites (Asn51, Asn301, Asn478) and the occupancy of at least one of these two sites (Asn51 and Asn301) is necessary for AtXylT stability and activity. Contribution of the N-terminal part of AtXylT in targeting and intracellular distribution of this protein was studied by expression of variably truncated, GFP-tagged AtXylT forms in tobacco cells using confocal and electron microscopy. These studies have shown that the transmembrane domain of AtXylT and its short flanking amino acid sequences are sufficient to specifically localize a reporter protein to the medial Golgi cisternae in tobacco cells. This study is the first detailed characterization of a plant glycosyltransferase at the molecular level.

Pitfalls and rewards of preferential crystallization

Abstract: The mirror symmetry relationship between enantiomers makes their separations by ‘classical’ separation methods difficult. When applicable, preferential crystallization is a productive and cost effective process which consists of alternate crystallizations of both enantiomers crystallizing as a conglomerate. Addition of in situ racemization to ‘classical’ preferential crystallization allows the yield to increase up to 100% in a single batch operation. Furthermore, the implementation of continuous ‘gentle’ grinding can solve the main problem of this method, i.e. the nucleation of the counter enantiomer. Preferential crystallization methodology can be also applied to any system composed of non symmetrical species. However, a set of thermodynamic and kinetic parameters must be determined for every compound that is supposed to crystallize selectively. This ‘highlight’ details the basic principles and the limitations of ‘classical’ preferential crystallization and its applications on ‘exotic’ systems by an extensive usage of phase diagrams.