Etude de la stabilité des interactions ioniques en phase gazeuse (application aux complexes biologiques.)

Les interactions non-covalentes (NCI pour Non-Covalent Interactions) stabilisant les complexes non-covalents biologiques (NCX pour Non-Covalent compleXes) régissent la majorité des processus cellulaires indispensables au développement et au bon fonctionnement de tout organisme vivant. Toutes les fonctions de l'ADN, tels que son conditionnement, sa réplication et la régulation de son expression, sont permises par la formation et la dissociation de NCI avec des protéines. La compréhension des bases de ces processus cellulaires de l'ADN au niveau moléculaire est un sujet d'actualité et d'une importance fondamentale. Des informations essentielles peuvent être obtenues par spectrométrie de masse (MS pour Mass Spectrometry) qui joue un rôle de plus en plus important dans ce domaine. Malgré la technologie avancée déjà mise en ¿uvre, le développement de nouveaux concepts d'ionisation et d'activation implémentent perpétuellement la MS. Les travaux de thèse exposés à travers ce manuscrit présente l'étude de la stabilité des NCI maintenant les NCX biologiques par la comparaison des voies de fragmentations observées en mode positif et en mode négatif mais aussi par l'application de certains concepts récents de la MS comme : (i) l'utilisation d'agents de " superchargement " et, (ii) le développement et l'utilisation d'une source V-EASI (pour Venturi Easy Ambiant Sonic-spray Ionization) permettant l'aspiration libre de la solution et la désorption/ionisation des analytes par la seule vélocité du gaz de nébulisation.Non-covalent interactions (NCI) stabilizing biological non-covalent complexes (NCX) lead most of cellular processes compulsory for the development and the functioning of all living organisms. All DNA functions, such as its conditioning, its replication and the regulation of its expression, are allowed by the formation and the dissociation of NCI with proteins. The comprehension of cellular processes basis of DNA at the molecular level is both topical and fundamental. Crucial information can be obtained by mass spectrometry (MS) which plays an increasing role in this field. Despite the already advanced technology applied, the development new ionization and activation concepts implement perpetually the MS. The Ph.D. work described through this manuscript presents the study of NCI maintaining the biological NCX by the comparison of fragmentation pathways observed in positive ion mode and in negative ion mode but also by the application of some recent MS concepts like: (i) the use of supercharging reagents and, (ii) the development and the use of a Venturi Easy Ambiant Sonic-spray Ionization (V-EASI) source allowing the free aspiration of the solution and the desorption/ionization of the analytes only by the velocity of the spraying gas.PARIS-JUSSIEU-Bib.électronique (751059901) / SudocSudocFranceF

Development of an electrospray-mass spectral database for annotating metabolomics datasets: application to the analysis of the adult human urinary metabolome

Metabolomics opens new perspectives for biomarker discovery in the field of nutrition and heath, and also in the development of system biology. The metabolic profiles of biofluids obtained by mass spectrometry or nuclear magnetic resonance contain a few hundreds to thousands of signals. However, a major part of this information remains unknown, or at least not characterized in the analytical systems, thus hampering the obtention of biologically meaningfull data. In this context, we here report on the development of an electrospray (ESI) spectral database for the annotation of high resolution mass spectrometry based metabolomics data sets and on its application to the analysis of urine samples from a cohort of healthy volunteers

0400: Degenerative calcific mitral stenosis in patients referred for high surgical risk aortic stenosis: detection and quantification by multi-detector computed tomography

BackgroundMitral annular calcifications (MAC) is a common finding in elder patients referred for transcatheter aortic valve implantation (TAVI), sometimes responsible of significant degenerative calcified mitral stenosis (CaMS), but prevalence of both is poorly defined. Multidectector computed tomography (MDCT) allows fine quantification of calcifications and is a reliable tool in rheumatic mitral stenosis, but its contribution in CaMS remains unknown. Our objective was to estimate prevalence of MAC and CaMS in patients referred for TAVI using MDCT, and determine morphological factors leading from MAC to CaMS.Methods and resultsA cohort of 346 consecutive patients referred for TAVI evaluation was screened by MDCT for MAC. One hundred and seventy four patients were positive for MAC. Among these patients, 165 patients had mitral valve area (MVA) assessable by MDCT planimetry (mean age 84 years). Analysis by segment revealed calcifications on: A1 30.9%, A2 29.1%, A3 42.4%, P1 56.4%, P2 78.8%, P3 69.7%. Mean mitral calcification volume and MVA were 1020±1398mm3 and 246±90mm 2, respectively. CaMS were severe, moderate and mild in 2.4%, 21.8% and 9.7% patients, respectively. Correlation between mitral calcification volume and MVA was significant but moderate (r=–0.433). On multivariate analysis, MVA was independently linked to mitral calcification volume, aortic annular area and specific patterns of mitral leaflet calcification underlining the role of A2 (AUC 0.81). Interobserver reproducibility of MVA was high (ICC 0.935).ConclusionsMDCT allows detailed assessment of MAC in TAVI populations, demonstrating high prevalence, and quantification of CaMS with high reproducibility. Mitral analysis should become routine during MDCT screening before TAVI as it may significantly alter the therapeutic strategy