Can we sort out from the jumble about oral contraceptives and skin cancers?

peer reviewedSkin contains various hormonal receptors, particularly those for estrogens, progesterone and androgens. Steroid hormones of oral contraceptives affect the skin, in particular the control of the cell cycle, DNA replication, apoptosis and other cellular functions. Some estrogen-responsive pathways have the potential to promote tumor development. The question of whether oral contraceptives increase the risk for the development of skin cancer, particularly melanoma, remains an area of concern. There is some evidence that steroid hormones present in oral contraceptives do not significantly increase the risk of developing skin cancer when estrogen exposure is not excessive

Les Complexes du Ruthénium (II), Photosondes de l'ADN: Augmentation de l'Affinité par la Fonctionnalisation et Stratégies de Synthèse pour le Contrôle de la Stéréochimie

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Bifunctional transition metal complexes as nucleic acids photoprobes and photoreagents

Transition metal complexes that bind to DNA have been the focus of extensive research aimed at increasing the understanding of genetic information processing and at developing ways to interfere with these mechanisms. Beside the continuous development of “dark reacting” artificial metallonucleases and metal-based chemotherapeutics such as cisplatin, photo-active octahedral metal complexes have been successfully used as DNA luminescent probes and light-driven reactive agents during the last decades. A recent emerging trend to improve their potential as molecular tools for studies of the genetic material is the design of bifunctional assemblies where the photo-active metal center is tethered through a flexible linker to a nucleic acid recognition or reactive moiety. This mini-review highlights some recent progresses in developing such bifunctional complexes through derivatization strategies ranging from the design of dimeric complexes and chromophore-quencher systems to the development of biotin–metal complex conjugates for avidin-mediated detection of biomolecules.SCOPUS: sh.jinfo:eu-repo/semantics/publishedMini-Revie

Skin tanning and skin bleaching: ethnic addictions complying with the latest fad

peer reviewedSun is at the origin of life and is responsible for death as well. In the past decades cutaneous melanoma has affected more and more young adults. In the White population, sun exposures and sunbeds are pointed out as the main culprits responsible for addictive behaviour. Preventive measures to be taken aim at avoiding the effects of ultraviolet light addiction. Sunlight exposure particularly in moderation is indeed beneficial through vitamin D3 synthesis and improved psychological wellbeing. Hence, we are facing the dilemma between too much and too little ultraviolet light exposure.In the Black population, the reverse situation is prevalent. It concerns skin depigmentation which may turn out to be a caricature in some subjects

Effets d'un stress aigu sur le rappel mnésique (approches comportementale, pharmacologique et électrophysiologique chez la souris)

L'objectif de cette thèse était d'étudier les effets neurobiologiques et comportementaux d'un stress aigu sur le rappel mnésique chez la souris. Afin d'identifier les structures cérébrales impliquées dans l'interaction stress-mémoire, le comportement d'animaux porteurs de lésions cérébrales sélectives (approche lésionnelle par microinjections d'acide iboténique) a été évalué dans une épreuve de discriminations spatiales (épreuve DSCS). Le rôle de corticostérone (homone du stress) sur le rappel mnésique a été étudié par une approche pharmacologique (injections périphérique, injections centrales et microdialyse intracérébrale). Par ailleurs, l'interaction dynamique des structures cérébrales impliquées a été évaluée en corrélant les enregistrements électrophysiologiques intracérébraux (potentiel de champs locaux) avec le comportement de souris stressées soumise à l'épreuve DSCS. Les résultats montrent que le stress perturbe sélectivement la restitution d'informations sérielles contextuelles (de type épisodique) alors qu'il est sans effet apparent sur la reconnaissance d'informations spatiales (de type sémantique). Les effets du stress sont en partie sous-tendus par l'activité antagoniste du cortex préfrontal et de l'hippocampe. L'interaction dynamique et transitoire entre ces deux structures semble fonction de l'état émotionnel de l'animal et sous-tendue par l'activité du noyau basolatéral de l'amygdale et/ou du noyau médiodorsal thalamique. La corticostérone, induite par le stress aigu, perturbe la restitution d'informations contextuelles en modulant l'activité de lhippocampe dorsal par l'activation de récepteur(s) membranaire(s).BORDEAUX1-BU Sciences-Talence (335222101) / SudocSudocFranceF

Virus-induced cancers: interplay between genetics and environment

peer reviewedAmong cancers diagnosed worldwide on a yearly basis, 20% are thought to be associated with a viral infection. The viruses involved are, by order of decreasing incidence, the hepatitis viruses, the papillomaviruses and the Epstein-Barr virus. These virus-induced cancers generate a high level of interest not only for the study of mechanisms involved in the neoplastic transformation, but also for the set-up of specific immunotherapies including prophylactic and therapeutic antitumor vaccination

Interactions of chiral Ru(II) complexes with CT-DNA

info:eu-repo/semantics/nonPublishe

Enantioselective luminescence quenching of DNA light-switch [Ru(phen) 2dppz]2+ by electron transfer to structural homologue [Ru(phendione)2dppz]2+

The quenching of the luminescence of [Ru(phen)2dppz] 2+ by structural homologue [Ru(phendione)2dppz] 2+, when both complexes are bound to DNA, has been studied for all four combinations of Δ and Λ enantiomers. Flow linear dichroism spectroscopy (LD) indicates similar binding geometries for all the four compounds, with the dppz ligand fully intercalated between the DNA base pairs. A difference in the LD spectrum observed for the lowest-energy MLCT transition suggests that a transition, potentially related to the final localization of the excited electron to the dppz ligand in [Ru(phen)2dppz]2+, is overlaid by an orthogonally polarized transition in [Ru(phendione) 2dppz]2+. This would be consistent with a low-lying LUMO of the phendione moiety of [Ru(phendione)2dppz]2+ that can accept the excited electron from [Ru(phen)2dppz]2+, thereby quenching the emission of the latter. The lifetime of excited A-[Ru(phen)2dppz]2+ is decreased moderately, from 664 to 427 ns, when bound simultaneously with the phendione complex to DNA. The 108 ns lifetime of opposite enantiomer, A-[Ru(phen)2dppz]2+, is only shortened to 94 ns. These results are consistent with an average rate constant for electron transfer of approximately 1·106 s -1 between the phenanthroline- and phendione-ruthenium complexes. At binding ratios close to saturation of DNA, the total emission of the two enantiomers is lowered equally much, but for the A enantiomer, this is not paralleled by a decrease in luminescence lifetime. A binding isotherm simulation based on a generalized McGhee - von Hippel approach shows that the Δ enantiomer binds approximately 3 times stronger to DNA both for [Ru(phendione)2dppz]2+ and [Ru(phen)2dppz] 2+. This explains the similar decrease in total emission, without the parallel decrease in lifetime for the A enantiomer. The simulation also does not indicate any significant binding cooperativity, in contrast to the case when Δ-[Rh(phi)2bipy]3+ is used as quencher. The very slow electron transfer from [Ru-(phen)2dppz]2+ to [Ru(phendione)2dppz]2+, compared to the case when [Rh(phi)2phen]3+ is the acceptor, can be explained by a much smaller driving free-energy difference. © 2005 American Chemical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Enantioselective luminescence quenching of DNA light-switch [Ru(phen) 2dppz]2+ by electron transfer to structural homologue [Ru(phendione)2dppz]2+

The quenching of the luminescence of [Ru(phen)2dppz] 2+ by structural homologue [Ru(phendione)2dppz] 2+, when both complexes are bound to DNA, has been studied for all four combinations of Δ and Λ enantiomers. Flow linear dichroism spectroscopy (LD) indicates similar binding geometries for all the four compounds, with the dppz ligand fully intercalated between the DNA base pairs. A difference in the LD spectrum observed for the lowest-energy MLCT transition suggests that a transition, potentially related to the final localization of the excited electron to the dppz ligand in [Ru(phen)2dppz]2+, is overlaid by an orthogonally polarized transition in [Ru(phendione) 2dppz]2+. This would be consistent with a low-lying LUMO of the phendione moiety of [Ru(phendione)2dppz]2+ that can accept the excited electron from [Ru(phen)2dppz]2+, thereby quenching the emission of the latter. The lifetime of excited A-[Ru(phen)2dppz]2+ is decreased moderately, from 664 to 427 ns, when bound simultaneously with the phendione complex to DNA. The 108 ns lifetime of opposite enantiomer, A-[Ru(phen)2dppz]2+, is only shortened to 94 ns. These results are consistent with an average rate constant for electron transfer of approximately 1·106 s -1 between the phenanthroline- and phendione-ruthenium complexes. At binding ratios close to saturation of DNA, the total emission of the two enantiomers is lowered equally much, but for the A enantiomer, this is not paralleled by a decrease in luminescence lifetime. A binding isotherm simulation based on a generalized McGhee - von Hippel approach shows that the Δ enantiomer binds approximately 3 times stronger to DNA both for [Ru(phendione)2dppz]2+ and [Ru(phen)2dppz] 2+. This explains the similar decrease in total emission, without the parallel decrease in lifetime for the A enantiomer. The simulation also does not indicate any significant binding cooperativity, in contrast to the case when Δ-[Rh(phi)2bipy]3+ is used as quencher. The very slow electron transfer from [Ru-(phen)2dppz]2+ to [Ru(phendione)2dppz]2+, compared to the case when [Rh(phi)2phen]3+ is the acceptor, can be explained by a much smaller driving free-energy difference. © 2005 American Chemical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe