RBE modelization: Present Status and Future Prospects

AVIR

Modélisation biomécanique du diaphragme humain : du CT-4D au modèle du mouvement

Session "Articles"National audienceL'hadronthérapie est une technique avancée de traitement du cancer par radiothérapie. Elle offre une balistique d'irradiation bien supérieure à la radiothérapie conventionnelle. Lorsque la tumeur se trouve sur un organe en mouvement, la difficulté majeure est de pouvoir la cibler pendant le traitement. En ce qui concerne la tumeur pulmonaire, le diaphragme joue un rôle majeur et prépondérant dans le mouvement tumoral. Le diaphragme est une membrane musculo-tendineuse en forme de dôme qui sépare le thorax de l'abdomen. Dans ce travail nous présentons un modèle biomécanique permettant de modéliser les mouvements du diaphragme pendant la respiration. Dans cette démarche nous simulons le mouvement du diaphragme entre l'inspiration et l'expiration, à partir d'un modèle de contraction musculaire. Pour cela, un modèle biomécanique 3D personnalisé du diaphragme, basé sur la méthode des éléments finis, a été développé à partir de données expérimentales (4D CT-scan) d'un patient. Les résultats de notre modélisation montrent une bonne concordance entre la simulation et les données expérimentales

Statistical effects of dose deposition in track-structure modelling of radiobiology efficiency

Ion-induced cell killing has been reported to depend on the irradiation dose but also on the projectile parameters. In this paper we focus on two approaches developed and extensively used to predict cell survival in response to ion irradiation: the Local Effect Model and the Katz Model. These models are based on a track-structure description summarized in the concept of radial dose. This latter is sensitive to ion characteristics parameters and gives to both models the ability to predict some important radiobiological features for ion irradiations. Radial dose is however an average quantity, which does not include stochastic effects. These radiation-intrinsic effects are investigated by means of a Monte-Carlo simulation of dose deposition. We show that both models are not fully consistent with the nanometric and microscopic dose deposition statistics.Comment: 32 pages ; 8 figure

Virus preparations from the mixed-infected P70 Pinot Noir accession exhibit GLRaV-1/GVA ‘end-to-end’ particles

P70 is a Pinot Noir grapevine accession that displays strong leafroll disease symptoms. A high-throughput sequencing (HTS)-based analysis established that P70 was mixed-infected by two variants of grapevine leafroll-associated virus 1 (GLRaV-1, genus Ampelovirus) and one of grapevine virus A (GVA, genus Vitivirus) as well as by two viroids (hop stunt viroid [HSVd] and grapevine yellow speckle viroid 1 [GYSVd1]) and four variants of grapevine rupestris stem pitting-associated virus (GRSPaV). Immunogold labelling using gold particles of two different diameters revealed the existence of ‘hybrid’ particles labelled at one end as GLRaV-1, with the rest labelled as GVA. In this work, we suggest that immunogold labelling can provide information about the biology of the viruses, going deeper than just genomic information provided by HTS, from which no recombinant or ‘chimeric’ GLRaV-1/GVA sequences had been identified in the dataset. Our observations suggest an unknown interaction between members of two different viral species that are often encountered together in a single grapevine, highlighting potential consequences in the vector biology and epidemiology of leafroll and rugose-wood diseases

Consistency checks of results from a Monte Carlo code intercomparison for emitted electron spectra and energy deposition around a single gold nanoparticle irradiated by X-rays

Organized by the European Radiation Dosimetry Group (EURADOS), a Monte Carlo code intercomparison exercise was conducted where participants simulated the emitted electron spectra and energy deposition around a single gold nanoparticle (GNP) irradiated by X-rays. In the exercise, the participants scored energy imparted in concentric spherical shells around a spherical volume filled with gold or water as well as the spectral distribution of electrons leaving the GNP. Initially, only the ratio of energy deposition with and without GNP was to be reported. During the evaluation of the exercise, however, the data for energy deposition in the presence and absence of the GNP were also requested. A GNP size of 50 nm and 100 nm diameter was considered as well as two different X-ray spectra (50 kVp and 100 kVp). This introduced a redundancy that can be used to cross-validate the internal consistency of the simulation results. In this work, evaluation of the reported results is presented in terms of integral quantities that can be benchmarked against values obtained from physical properties of the radiation spectra and materials involved. The impact of different interaction cross-section datasets and their implementation in the different Monte Carlo codes is also discussed

Louis-Ferdinand Céline, literary genius or national pariah? Defining moral parameters for influential cultural figures, post- Charlie Hebdo

In January 2011 the French Minister of Culture, Frédéric Mitterrand, withdrew Louis-Ferdinand Céline from a list of famous French authors specifically selected for a national celebration of culture. This bold decision polarized opinion: while many welcomed Mitterrand’s intervention, a number of prominent writers, some of them Jewish, opposed it on the grounds that Céline’s abhorrent political beliefs – expressed in three anti-Semitic pamphlets and his flirtation with Nazism- should in no way detract from his literary genius. In the light of this controversy, and of the rise in anti-Semitism following the Charlie Hebdo attacks of January 2015, this paper proposes Céline as a vital case study of the moral parameters a democratic nation should apply to a culturally important figure whose political views are deemed unacceptably reactionary

Theoretical approach based on Monte-Carlo simulations to predict the cell survival following BNCT

International audienceWe present here a very preliminary work on BNCT Dosimetry. The approach is as follows:A full Monte Carlo calculation is used to separate all dose components and determine the corresponding physical dose fractions with a realistic clinical model.These dose fractions are then used as mixed fields to predict cell-survivals and RBE values for a specific cell-line, thanks to the radiobiological model NanOxTM

Identification of Residues in the Heme Domain of Soluble Guanylyl Cyclase that are Important for Basal and Stimulated Catalytic Activity

Nitric oxide signals through activation of soluble guanylyl cyclase (sGC), a heme-containing heterodimer. NO binds to the heme domain located in the N-terminal part of the β subunit of sGC resulting in increased production of cGMP in the catalytic domain located at the C-terminal part of sGC. Little is known about the mechanism by which the NO signaling is propagated from the receptor domain (heme domain) to the effector domain (catalytic domain), in particular events subsequent to the breakage of the bond between the heme iron and Histidine 105 (H105) of the β subunit. Our modeling of the heme-binding domain as well as previous homologous heme domain structures in different states point to two regions that could be critical for propagation of the NO activation signal. Structure-based mutational analysis of these regions revealed that residues T110 and R116 in the αF helix-β1 strand, and residues I41 and R40 in the αB-αC loop mediate propagation of activation between the heme domain and the catalytic domain. Biochemical analysis of these heme mutants allows refinement of the map of the residues that are critical for heme stability and propagation of the NO/YC-1 activation signal in sGC