Vers une modélisation du comportement de la cavité pelvienne

L'incidence du prolapsus pelvien atteint une femme sur trois tous âges confondus, et plus de 60% des patientes de plus de 60 ans. La prise en charge chirurgicale de cette pathologie devient une préoccupation première en gynécologie. Malheureusement, le taux d'échec des différentes techniques opératoires est de l'ordre de 40%. Ces récidives seraient attribuées à une mauvaise adéquation entre le choix de la technique et la pathologie et/ou à l'utilisation de tissu mécaniquement déficient dans les montages chirurgicaux de soutien. La modélisation et la simulation du comportement de la cavité pelvienne seraient une méthode d'évaluation objective et spécifique des troubles de la statique pelvienne et des différentes techniques opératoires. Les premières étapes de réalisation de ce modèle ont été élaborées. La caractérisation des tissus pelviens impliqués en statique pelvienne a été réalisée à partir d'essais de traction uni-axiale. Les conditions aux limites ont été définies à partir d'imagerie dynamique du pelvis et un modèle numérique est en cours d'élaboration

Simulation des mobilités pelviennes : optimisation topologique du système ligamentaire

Le prolapsus génital féminin est un phénomène encore mal compris avec un taux d'échec des techniques chirurgicales élevé (de 10 à 40%). Nous proposons un modèle 3D de la cavité pelvienne construit à partir d'images IRM d'une patiente saine. Les résultats numériques sont comparés avec des analyses de champs de déplacements issus d images IRM dynamiques de la même patiente en effort de poussée. L'introduction progressive des ligaments et des conditions aux limites tout en quantifiant l'écart à la réalité nous mène vers un modèle cohérent permettant une étude de sensibilité

Towards a better understanding of pelvic system disorders using numerical simulation

International audienceGenital prolapse is a pathologic hyper-mobility of the organs that forms the pelvic system. Although this is common condition, the pathophysiology of this disorder is not well known. In order to improve the understanding of its origins, we recreate - virtually - this biomechanical pathology using numerical simulation. The approach builds on a finite element model with parameters measured on several fresh cadavers. The meshes are created from a MRI of a healthy woman and the simulation includes the mechanical interactions between organs (contacts, ligaments, adhesion...). The model is validated through comparison of functional mobilities of the pelvic system observed on a dynamic MRI. We then propose to modify, step by step, the model and its parameters to produce a pathologic situation and have a better understanding of the process. It is not a formal proof but the numerical experiments reinforce the clinical hypothesis on the multifactorial origins of the pathology

No Difference between the Sexes in Fine-Scale Spatial Genetic Structure of Roe Deer

Background: Data on spatial genetic patterns may provide information about the ecological and behavioural mechanisms underlying population structure. Indeed, social organization and dispersal patterns of species may be reflected by the pattern of genetic structure within a population. [br/] Methodology/Principal Findings: We investigated the fine-scale spatial genetic structure of a roe deer (Capreolus capreolus) population in Trois-Fontaines (France) using 12 microsatellite loci. The roe deer is weakly polygynous and highly sedentary, and can form matrilineal clans. We show that relatedness among individuals was negatively correlated with geographic distance, indicating that spatially proximate individuals are also genetically close. More unusually for a large mammalian herbivore, the link between relatedness and distance did not differ between the sexes, which is consistent with the lack of sex-biased dispersal and the weakly polygynous mating system of roe deer. [br/] Conclusions/Significance: Our results contrast with previous reports on highly polygynous species with male-biased dispersal, such as red deer, where local genetic structure was detected in females only. This divergence between species highlights the importance of socio-spatial organization in determining local genetic structure of vertebrate populations

Mercury content in commercial pelagic fish and its risk assessment in the Western Indian Ocean,” Sci.

Abstract As top predators of pelagic food webs, large fish naturally bioaccumulate mercury (Hg). Determining Hg burdens in commercialized fish is essential considering the concern about effects of contaminants on human health and the legal thresholds that are therefore set for local consumption and/or exportation. Total Hg levels were measured in the muscular tissue of 183 fish of five commercially important species from the tropical zone of the Western Indian Ocean. All individuals were measured and sexed in order to study the impregnation of Hg with size and sex within each species. Values of Hg found in this part of the Indian Ocean were comparable to Hg in muscular tissue of the same species studied in other areas. The highest Hg levels were noted in Swordfish (Xiphias gladius) caught in waters surrounding Reunion Island (3.97 ± 2.67 μg g − 1 dry weight). Following the Swordfish, in decreasing order of Hg content, were the Yellowfin Tuna (Thunnus albacares) and the Skipjack (Katsuwonus pelamis), then the Common Dolphinfish (Coryphaena hippurus) and the Wahoo (Acanthocybium solandri). In the North of the Mozambique Channel, Swordfish had higher Hg levels than Yellowfin Tunas, and Dolphinfish exhibited intermediate Hg levels. The size of a fish was a determining factor of its Hg burden, as was the species. Differences in size-normalized Hg levels were observed between the two study zones for Swordfish and Common Dolphinfish. Sex, in contrast, did not influence Hg levels suggesting that females and males have similar feeding habits. The muscular Hg levels presented here suggest that consumers of fish originating from theWestern Indian Ocean should limit themselves to one Swordfish based meal per week, or one fish meal a day if they choose to eat tuna or Common Dolphinfish

En quoi l'étude des îlots forestiers permet-elle de mieux connaître le fonctionnement de la forêt tropicale ?

Small forested islands isolated from surrounding tropical forest by new reservoirs provide a norm for interpreting the effects of fragmentating the forest by intervening agriculture and pasture, and an effective means of investigating the ecological organization of the mainland forest. Water is a more effective barrier to immigration and a more neutral matrix than field or pasture. On forest fragments isolated by water, the effects of fragmentation are minimally confounded with effects of the matrix, while forest fragments surrounded by fields and pastures may suffer intrusions from tire, domestic animals, and other pests. On small islands, some species will go extinct. If the extinction of a species is followed by increase in its prey or competitors, we may provisionally assume that on the mainland, these prey and competitors are lirnited by the species now absent from the island. If, when a tree's seed disperser disappears, new seedlings of that tree no longer appear, that tree's regeneration presumably depends on its seed disperser. Islands in new reservoirs are the tropical forest ecologist's closest analogue to the exclusion experiments so effective in understanding the ecology of intertidal comrnunities. Small islands in reservoirs can also serve as systems of replicates for experimental analysis of the causes of regulation of selected populations. We review work on small islands isolated in 1914 by Panama's Gatun Lake, islands isolated in 1986 by Venezuela's Lake Guri, and islets isolated in 1994 at Saint-Eugène in French Guiana. The more recently the islands have been isolated, the more can be Jeamed from them. The Saint-Eugène Fragmentation Project is particularly important because it is only one of the three in true rainforest and studies there have been done before and after fragmentationLes petites îles boisées qui sont isolées de la forêt tropicale voisine après la mise en eau de réservoirs en amont des barrages hydroélectriques constituent des modèles pour l'étude de la fragmentation forestière après mise en agriculture ou pâturage. Elles offrent ainsi aux écologistes un protocole expérimental pour l'étude des processus écologiques de la forêt de terre ferme. L'eau est une barrière plus efficace et joue un rôle plus neutre contre l'immigration que les champs ou les pâturages. Sur des fragments forestiers isolés par une matrice aquatique, les effets de la matrice, qui sont souvent confondus avec ceux de la fragmentation, sont ici minimaux, alors que des fragments forestiers entourés de champs et de pâturages ont à supporter les feux intrusifs et l'invasion des animaux domestiques et autres pestes. Sur les petites îles, quelques espèces vont disparaître. Si l'extinction d'une espèce y est suivie de l'augmentation de la population de ses proies ou d'autres espèces compétitrices, on peut provisoirement supposer que, sur le continent, ces proies et compétiteurs sont limités par cette espèce qui a aujourd'hui disparu sur l'île. Si, lorsque l'agent disséminateur des graines d'un arbre disparaît et que les jeunes plantules de cet arbre ne sont plus présentes, c'est que la régénération de l'arbre en était fortement dépendante. Les îles des récents réservoirs sont, pour les écologistes, des systèmes expérimentaux analogues aux expériences d'exclusion qui sont si utiles pour comprendre l'écologie des communautés, des zones intertidales en particulier. Les îlots des réservoirs peuvent également servir comme système de réplicats pour l'analyse des causes de la régulation de certaines populations. Dans cet article, nous présentons une revue des études menées sur les petites îles isolées en 1914 par les eaux du lac Gatun au Panama, les îles isolées en 1986 par le lac Guri au Vénézuela, et les îlots formés en 1994 à Saint-Eugène en Guyane française. Plus les îles se sont formées récemment, plus les enseignements qui en découlent sont riches. Le Projet Fragmentation de Saint-Eugène est particulièrement important car c'est le seul des trois sites cités a être réalisé dans une vraie forêt tropicale humide, et les études y ont été menées avant et après la fragmentatio

Modélisation des mobilités du système pelvien : vers une meilleure compréhension des troubles de la statique pelvienne

International audienceLe prolapsus génital est un trouble d'hyper-mobilité des organes du système pelvien touchant 60% des femmes de plus de 60 ans, dont la physiopathologie est encore mal connue. Afin de mieux comprendre les mécanismes à l'origine de cette pathologie, un modèle élément fini permettant de simuler les mobilités fonctionnelles du système pelvien a été développé. Ce modèle a été modifié pour tendre vers la situation pathologique, permettant de quantifier l'influence de chaque modification (propriétés mécaniques, évolution topologique des ligaments...) sur les mobilités du système

Do Surgeons Anticipate Women’s Hopes and Fears Associated with Prolapse Repair? A Qualitative Analysis in the PROSPERE Trial

Women’s preoperative perceptions of pelvic-floor disorders may differ from those of their physicians. Our objective was to specify women’s hopes and fears before cystocele repair, and to compare them to those that surgeons anticipate. We performed a secondary qualitative analysis of data from the PROSPERE trial. Among the 265 women included, 98% reported at least one hope and 86% one fear before surgery. Sixteen surgeons also completed the free expectations-questionnaire as a typical patient would. Women’s hopes covered seven themes, and women’s fears eleven. Women’s hopes were concerning prolapse repair (60%), improvement of urinary function (39%), capacity for physical activities (28%), sexual function (27%), well-being (25%), and end of pain or heaviness (19%). Women’s fears were concerning prolapse relapse (38%), perioperative concerns (28%), urinary disorders (26%), pain (19%), sexual problems (10%), and physical impairment (6%). Surgeons anticipated typical hopes and fears which were very similar to those the majority of women reported. However, only 60% of the women reported prolapse repair as an expectation. Women’s expectations appear reasonable and consistent with the scientific literature on the improvement and the risk of relapse or complication related to cystocele repair. Our analysis encourages surgeons to consider individual woman’s expectations before pelvic-floor repair

Trypanosoma vivax Infections: Pushing Ahead with Mouse Models for the Study of Nagana. II. Immunobiological Dysfunctions

Trypanosoma vivax is the main species involved in trypanosomosis, but very little is known about the immunobiology of the infective process caused by this parasite. Recently we undertook to further characterize the main parasitological, haematological and pathological characteristics of mouse models of T. vivax infection and noted severe anemia and thrombocytopenia coincident with rising parasitemia. To gain more insight into the organism's immunobiology, we studied lymphocyte populations in central (bone marrow) and peripherical (spleen and blood) tissues following mouse infection with T. vivax and showed that the immune system apparatus is affected both quantitatively and qualitatively. More precisely, after an initial increase that primarily involves CD4+ T cells and macrophages, the number of splenic B cells decreases in a step-wise manner. Our results show that while infection triggers the activation and proliferation of Hematopoietic Stem Cells, Granulocyte-Monocyte, Common Myeloid and Megacaryocyte Erythrocyte progenitors decrease in number in the course of the infection. An in-depth analysis of B-cell progenitors also indicated that maturation of pro-B into pre-B precursors seems to be compromised. This interferes with the mature B cell dynamics and renewal in the periphery. Altogether, our results show that T. vivax induces profound immunological alterations in myeloid and lymphoid progenitors which may prevent adequate control of T. vivax trypanosomosis