Should we consider Dupuytren's contracture as work-related? A review and meta-analysis of an old debate

International audienceABSTRACT: BACKGROUND: In view of the conflicting opinions published, a meta-analysis was undertaken on epidemiological studies in order to assess any association between Dupuytren's contracture and work exposure. METHODS: Using the key words: "occupational disease", "work" and "Dupuytren contracture" without limitation on language or year of publication, epidemiological studies were selected from four databases (Pub-Med, Embase, Web of science, BDSP) after two rounds (valid control group, valid work exposure). A quality assessment list was constructed and used to isolate papers with high quality methodological criteria (scores of 13 or above, HQMC). Relevant associations between manual work, vibration exposure (at work) and Dupuytren's contracture were extracted from the articles and a metarisk calculated using the generic variance approach (meta-odds ratios, meta-OR). RESULTS: From 1951 to 2007, 14 epidemiological studies (including 2 cohort studies, 3 case-control studies, and 9 cross-sectional studies/ population surveys) were included. Two different results could be extracted from five studies (based on different types of exposure), leading to 19 results, 12 for manual work (9 studies), and 7 for vibration exposure (5 studies). Six studies met the HQMC, yielding 9 results, 5 for manual work and 4 for vibration exposure. Five studies found a dose-response relationship. The meta-OR for manual work was 2.02[1.57;2.60] (HQMC studies only: 2.01[1.51;2.66]), and the meta-OR for vibration exposure was 2.88 [1.36;6.07] (HQMC studies only: 2.14[1.59;2.88]). CONCLUSION: These results support the hypothesis of an association between high levels of work exposure (manual work and vibration exposure) and Dupuytren's contracture in certain cases

Dynamique de repliement des protéines étudiées par dichroïsme circulaire résolu en temps.

To express its biological function, a protein has to adopt a spatial conformation, which is unique and precisely defined. One uses the terms "folding" of the protein towards its "native" structure. Understanding the mechanisms of this process is currently one of the main stakes in biophysical research. In this context, we have set up a new technique to measure circular dichroism. It allows us to follow with precision the structural dynamics of small chiral molecules in liquid phases and over picoseconds to nanoseconds timescales. When applied in the ultraviolet spectral region, it can be used to study the first steps of secondary structures folding. The principle of this technique relies on the measurement of the ellipticity induced by a chiral sample on a linearly polarized incident beam. After having introduced this new method, we will explain how to experimentally make use of it. Then we will compare it to usual techniques employed to measure circular dichroism and will apply it to the study of three molecules (myoglobine, [Ru(phen)3]2+, 1,1'-Binaphthol). Finally, we will examine the first experimental results obtained within the framework of the folding study of model alpha helices. Two techniques that can be used to initiate the folding process will be described: optical excitation of a chromophore located at the extremity of the polypeptide chain, and optical initiation of a temperature jump.Pour exprimer sa fonction biologique, une protéine doit adopter une conformation spatiale unique et très précisément définie. On parle de " repliement " vers la structure " native ". La compréhension des mécanismes accompagnant ce processus est actuellement l'un des principaux enjeux de la recherche en biophysique. Dans ce contexte, nous avons mis en place une technique originale de mesure du dichroïsme circulaire, permettant de suivre avec précision les dynamiques structurales de petites molécules chirales en phase aqueuse, sur des échelles de temps allant de la picoseconde à la nanoseconde. Appliquée dans le domaine de l'ultraviolet, elle permet d'étudier les premières étapes du repliement de structures secondaires modèles. Le principe de cette technique repose sur la mesure de l'ellipticité induite par un milieu chiral sur une onde initialement polarisée linéairement. Après avoir présenté cette nouvelle méthode, nous montrerons comment la mettre en œuvre expérimentalement. Nous la comparerons ensuite aux techniques usuelles de mesure du dichroïsme circulaire, et l'appliquerons à l'étude de trois molécules (myoglobine, [Ru(phen)3]2+, 1,1'-Binaphthol). Enfin, nous nous intéresserons aux premiers résultats expérimentaux obtenus dans le cadre de l'étude du repliement en hélices alpha de polypeptides modèles. Deux techniques d'initiation du repliement seront examinées : l'excitation optique d'un chromophore greffé à l'extrémité de la chaîne peptidique, puis l'induction optique d'un saut de température

Measuring the dynamics of circular dichroism in a pump-probe experiment with a Babinet-Soleil compensator

International audienceCircular dichroism contains rich information on the conformation of molecules and, in particular, of biomolecules, and measuring its variation in a pump-probe experiment is very promising but also very challenging. We propose a new technique to measure pump-induced variation of the circular dichroism, which is based on the measurement of the probe ellipticity and its variation with the pump. This technique has the advantage that it does not require modulation of the probe polarization, which allows modulation of the pump intensity. We show theoretically and demonstrate experimentally that this technique is very sensitive and user friendly. We also show that it can be used to measure pump-induced change in the optical rotation, allowing for a complete characterization of pump-induced optical activity. Cop. 2006 Optical Society of America

Conformational changes in photoexcited (R)-(+)-1,1'-bi-2-naphthol studied by time-resolved circular dichroism

International audienceConformational changes following photoexcitation of (R)-(+)-1,1′-bi-2-naphthol are studied with a time-resolved circular dichroism (CD) experiment. Two wavelengths are investigated. For λ = 237 nm, we observe a bleaching of the ground-state absorption and a transient CD structure. Thanks to a coupled-oscillator calculation, we can attribute this effect to a decrease of the dihedral angle. For λ = 245 nm, excited-state absorption and CD are observed. All these effects are solvent-dependent. In particular, it is shown that dynamics is slower in a protic solvent, which is attributed to hydrogen-bonding of the hydroxy groups with the solvent

Une nouvelle technique de mesure du dichroïsme circulaire (premiers pas vers l'étude du repliement de polypeptides modèles)

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

A new technique to measure time-resolved circular dichroism : ultrafast conformational dynamics of 1,1'-bi-2-naphthol

International audienceUsing a new technique to measure time-resolved circular dichroism in a pump-probe experiment, we study the conformational relaxation in photoexcited (R)-(+)-1,1'-Bi-2- naphthol. The dihedral angle decreases of ca 20-30° in 100 psec in Ethanol

Excited-state absorption and circular dichroism of ruthenium(II) tris(phenanthroline) in the ultraviolet region

International audienceExcitation of ruthenium(II) tris(phenanthroline) in the visible region results in the tranfer of an electron from the central atom toward one of the ligands. To probe this excited state, we have performed pump-induced absorption and circular dichroism in the ultraviolet wavelengths, in the intraligand p-p* transition region. On top of the bleaching of the ground state transitions, new structures appear in the absorption and CD spectra. Thanks to a classical calculation based on the polarizability theory, we can interpret these features as the result of a strong reduction of the excitonic coupling due to a blue shift of the p-p* transition in the reduced ligand accompanied by the onset of new excited-state transitions. Cop. 2007 American Chemical Society