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Four instances of sudden death in childhood and adolescence with autopsy findings are presented. In the four cases unsuspected cystic medionecrosis of the aorta was discovered. In three of the four patients it was associated with a cardiovascular malformation, viz (1) double coarctation of the aorta, (2) coarctation of the aorta associated with Ebstein anomaly, and (3) subvalvular aortic stenosis. In three patients ocular abnormalities were demonstrated as an additional autopsy finding. Only one child could be said to have the Marfan habitus. We suggest that until new biological criteria emerge such observations should remain classified under the eponym of Marfan syndrome.

Brief aus Nogent sur Marne, mit Erwähung der Zulassung von Louis Rollier als Privatdozent (ab 1903), ETH-Bibliothek

Analysis of the 3D structure of a biological sample is an important step to model cell and tissue dynamics. As a model system, we set up to determine the number of nuclei in a follicular papilla using confocal imaging and 3D computer reconstruction. The follicular papilla is a small mesenchymal ovalshape structure localized at the basis of the hair follicle that is particularly important for hair follicle morphogenesis, and the size of which varies during hair growth. However, little is known on the influence of the hair cycle on the number of cells in a follicular papilla. Fgf5 -/- mice have long hairs (angora phenotype) due to an extended hair cycle, and small dermal papilla. There are several hypotheses to explain the latter observation : there are less cells in Fgf5 -/- dermal papilla than in wild type papilla mutant papilla produces less extra cellular matrix than wild type papilla it is a combination of both To discriminate between these hypotheses, dermal papilla were microdissected from vibrissal follicles occupying the same position on the mystacial pad of same age Fgf5 -/- and wild type mice. Nuclei were stained with a fluorescent dye and the papilla examined under a confocal microscope. Because of dermal papilla thickness, two stacks of images were acquired for each sample (recto and verso acquisitions), registrated using especially implemented computer science program and analyzed. This whole process turned out to be far more complex and cumbersome than anticipated. First, we had to design a special setup in order to be able to make two side scans of samples, second the acquisition time of two stacks of images to cover the entire dermal papilla was rather long, third repositioning and analysis of the images were complex. Nonetheless, the number of nuclei in a dermal papilla was determined with precision. Analysis of dermal papilla obtained at different time of the hair cycle is ongoing. Our work paves the way to the analysis of other biological structures important during skin morphogenesis or regeneration, i.e. the ectodermal placodes. An important lesson of our work is that there is no straightforward imaging and computer science approach when it comes to the biology of complex structures and that the technology needs to be customized to the biological question.

National audience; Vous pensez que l'évolution des espèces peut se représenter par un arbre ? La transmission de matériel génétique entre espèces co-existantes est pourtant très fréquente dans le monde du vivant. Transfert de gènes entre deux espèces de bactéries, apparition d'une espèce hybride, recombinaison entre deux souches de virus, divers phénomènes biologiques conduisent des branches de l'arbre à se rejoindre : on obtient alors un réseau des espèces. Mais si l'on considère un gène en particulier, son histoire reste le plus souvent représentée sous forme d'un arbre. Comment trouver l'arbre d'un gène à l'intérieur du réseau des espèces ? Il s'agit d'un problème informatique difficile, mais pour lequel plusieurs méthodes de résolution ont été trouvées quand le réseau a des propriétés particulières. Cet atelier vise à faire manipuler certains exemples du problème pour prendre conscience de sa difficulté : arriverez-vous à retrouver l'arbre dans le labyrinthe du vivant ?

International audience; Les genres du fantastique et de la fantasy remportent un succès de plus en plus grand auprès des jeunes lecteurs. Un des facteurs d’explication de ce développement tient sans doute à la représentation originale qui s’y trouve proposée, des âges et de leurs frontières, que ce soit au niveau formel ou thématique. S’appuyant sur les plus anciens symboles et mythes de la métamorphose, les œuvres contemporaines les mettent au service des problématiques de leur temps : la littérature de jeunesse n’est plus seulement le domaine de l’enfance éternisée, elle intègre au contraire les changements accélérés des mutations adolescentes.

International audience