Etude de l'atmosphère ionique et de la stabilité de la structure double brin d'oligonucléotides par RMN du 23Na

Doctorat en sciences appliquéesinfo:eu-repo/semantics/nonPublishe

23-Na Studies of the stability of double stranded oligonucleotides

info:eu-repo/semantics/nonPublishe

CFD-aided optimisation of the performance of a Couette-Taylor bioreactor for animal cell culture

info:eu-repo/semantics/publishe

Na-23 and H-1 NMR study of the stability and dynamics of double stranded oligonucleotides

info:eu-repo/semantics/nonPublishe

Etude des performances d'un réacteur de Couette-Taylor pour la culture des cellules animales

Ce travail traite de l’optimisation de la culture de cellules animales dans un réacteur de Couette-Taylor. Ce réacteur possède la propriété intéressante de fournir un mélange non négligeable en régime laminaire. L’étude de l’hydrodynamique de l’écoulement dans l’appareil est réalisée à l’aide d’un logiciel de dynamique des fluides (CFD). Les résultats des simulations CFD sont en accord avec des résultats de visualisation laser (PIV). Sur base de ces études, un modèle en compartiments du réacteur est proposé, dont les différents paramètres sont identifiés grâce à des essais de traceur (DTS). Les performances du réacteur sont alors évaluées, sur base d’un modèle simple de croissance cellulaire implémenté sur le modèle à compartiments.info:eu-repo/semantics/publishe

L'archéologie de l'Afrique centrale

info:eu-repo/semantics/publishe

Growth inhibition of human in vitro and mouse in vitro and in vivo mammary tumor models by retinoids in comparison with tamoxifen and the RU-486 anti-progestagen.

Retinoids constitute a very promising class of agents for the chemoprevention or treatment of breast cancer. These retinoids exert their biological activity through two distinct classes of retinoic acid (RA) receptors (R), the RAR isotypes (alpha, beta, and gamma) and the three RXR isotypes (alpha, beta, and gamma) and their numerous isoforms which bind as RXR/RAR heterodimers to the polymorphic cis-acting response elements of RA target genes. With respect to these numerous receptor sub-types, the retinoid-induced effects at the biological level include marked modifications with respect to both cell proliferation and cell death (apoptosis), and also in the induction of differentiation processes. The present study aims to characterize the effect which four retinoids (TTNPB, 9-cis-RA, LGD 1069, 4-HPR) with distinct RAR/RXR binding properties induced on various in vitro and in vivo mouse and human breast cancer models. The experiments with the retinoids were carried out in comparison with the anti-estrogen tamoxifen and the anti-progestagen RU-486 compounds. The results show that the 6 compounds under study were markedly more efficient in terms of growth inhibition in the human T-47D cell line when maintained under anchorage-independent culture conditions than when maintained under anchorage-dependent ones. While RU-486 exhibited a weak statistically significant (p 0.05) significant influence on the growth of the stem cells. The most efficient retinoid was TTNPB. It was only at the highest dose (10 microM) that tamoxifen and RU-486 showed a weak inhibitory influence on the growth of the T-47D non-stem cells while all 4 retinoids exerted a significant inhibitory influence on the growth of these non-stem cells, with 4-HPR being the most efficient (P 0.05) at the lowest. Tamoxifen and TTNPB were tested in vivo on hormone-sensitive (HS) and hormone-insensitive (HI) strains of the MXT murine mammary carcinoma. While TTNPB appeared to be equally efficient in terms of growth inhibition in both MXT-HS and MXT-HI models, tamoxifen had only a marginal inhibitory influence on the growth of the MXT-HI strain but did inhibit growth in the case of the MXT-HS one. TTNPB was markedly more efficient than tamoxifen in terms of both inhibiting the cell proliferation level (measured by means of computer-assisted microscopy applied to Feulgen-stained nuclei, a method which enables the percentage of cells in the S phase of the cell cycle to be determined) and triggering cell death (measured by means of the determination of the transglutaminase activity) in both the MXT-HI and MXT-HS models. The very significant TTNPB-induced inhibition of the macroscopic MXT-HS growth rate relates to the triggering of cell death (apoptosis) rather than to an inhibition of cell proliferation. All these results clearly indicate that retinoids are very efficient agents against breast cancer, at least as efficient as tamoxifen.Comparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe