« Quelle belle vie ! ». L'existence poétisée du Charlot de Philippe Soupault

Dans Charlot (1931), Philippe Soupault narre la vie imaginaire du célèbre vagabond, à partir des films qu'il a vus et des souvenirs qu'il en a gardés. Mais il la retrace en la poétisant : tenant Charlot pour un « poète au sens le plus pur et le plus fort du terme », l'écrivain accorde son récit à l'image qu'il se fait du personnage. La figuration poétique s'effectue ainsi de manière à la fois thématique et formelle : non seulement le parcours de Charlot voisine par intermittence avec ceux de modèles emblématiques (Orphée, Croniamantal, Rimbaud, Cendrars), mais son existence elle-même est perçue à l'image d'un poème, structurée selon un schéma cyclique. Dès lors, et dans tous les sens du terme, le récit de Soupault peut être défini comme une biographie poétique - par l'existence qu'il restitue, par le style qu'il emploie, par l'émotion qu'il procure.

A musculoskeletal shoulder model based on pseudo-inverse and null-space optimization.

The goal of the present work was assess the feasibility of using a pseudo-inverse and null-space optimization approach in the modeling of the shoulder biomechanics. The method was applied to a simplified musculoskeletal shoulder model. The mechanical system consisted in the arm, and the external forces were the arm weight, 6 scapulo-humeral muscles and the reaction at the glenohumeral joint, which was considered as a spherical joint. The muscle wrapping was considered around the humeral head assumed spherical. The dynamical equations were solved in a Lagrangian approach. The mathematical redundancy of the mechanical system was solved in two steps: a pseudo-inverse optimization to minimize the square of the muscle stress and a null-space optimization to restrict the muscle force to physiological limits. Several movements were simulated. The mathematical and numerical aspects of the constrained redundancy problem were efficiently solved by the proposed method. The prediction of muscle moment arms was consistent with cadaveric measurements and the joint reaction force was consistent with in vivo measurements. This preliminary work demonstrated that the developed algorithm has a great potential for more complex musculoskeletal modeling of the shoulder joint. In particular it could be further applied to a non-spherical joint model, allowing for the natural translation of the humeral head in the glenoid fossa.

Agenesis of human pancreas due to decreased half-life of insulin promoter factor 1.

Neonatal diabetes mellitus can be transient or permanent. The severe form of permanent neonatal diabetes mellitus can be associated with pancreas agenesis. Normal pancreas development is controlled by a cascade of transcription factors, where insulin promoter factor 1 (IPF1) plays a crucial role. Here, we describe two novel mutations in the IPF1 gene leading to pancreas agenesis. Direct sequence analysis of exons 1 and 2 of the IPF1 gene revealed two point mutations within the homeobox in exon 2. Genetic analysis of the parents showed that each mutation was inherited from one parent. Mutations localized in helices 1 and 2, respectively, of the homeodomain, decreased the protein half-life significantly, leading to intracellular IPF1 levels of 36% and 27% of wild-type levels. Both mutant forms of IPF1 were normally translocated to the nucleus, and their DNA binding activity on different known target promoters was similar to that of the wild-type protein. However, transcriptional activity of both mutant IPF1 proteins, alone or in combination with HNF3 beta/Foxa2, Pbx1, or the heterodimer E47-beta 2 was reduced, findings accounted for by decreased IPF1 steady state levels and not by impaired protein-protein interactions. We conclude that the IPF1 level is critical for human pancreas formation.