Interstellar H^+_3: possible detection of the 1_(10)→1_(11) transition of H_2D^+

An interstellar line has been detected in emission at the expected submillimeter wavelength of the 1_(10)→1_(11) transition of H_(2)D^+, the deuterated version of the primary ion (H^(+)_(3)) in the favored ion-molecule reaction scheme for interstellar gas phase chemistry. The strength of the line is in approximate agreement with the theoretically anticipated H_(2)D^+ abundance

Recension exploratoire d’écrits sur les fiducies foncières, les biens communs et le droit communal

Université du Québec à Montréal (UQAM) Département SociologieLa réalisation de cette étude exploratoire s’inscrit dans une démarche de recherche-action initiée par Éric Pineault du département de sociologie de l’UQAM et Jocelyn Darou, alors étudiant au programme de maîtrise du même département. Une subvention de recherche de trois mille dollars fut obtenue du Centre de recherche sur les innovations sociales (CRISES) pour produire une recension d’écrits sur les fiducies foncières en lien avec le domaine de l’agriculture biologique. A été associé à la démarche l’organisme Protec-Terre (http://www.protec-terre.org). Le présent rapport rend compte de l’étude qui fut réalisée. Il est divisé en trois sections. La première section présente le travail de recension effectué par Jocelyn Darou. La deuxième section porte sur la question des biens communs. Elle a été réalisée par Claude Côté, présentement étudiant de premier cycle au département de sociologie. La troisième section situe brièvement la question des biens communs dans le contexte général des développements historiques qu’a connus la question des « droits de propriété ». La méthodologie de recherche utilisée était relativement simple. Elle a consisté en une recension d’écrits réalisée principalement à partir de documents thématiques en langues française et anglaise consultés sur Internet et portant sur : • les fiducies foncières ; • la notion de bien commun ; • la question du droit en lien avec la notion de communalité

N-3 polyunsaturated fatty acids stimulate bile acid detoxification in human cell models

Cholestasis is characterized by the accumulation of toxic bile acids (BAs) in liver cells. The present study aimed to evaluate the effects of n-3 polyunsaturated fatty acids (n-3 PUFAs), such as docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids, on BA homeostasis and toxicity in human cell models. The effects of EPA and/or DHA on the expression of genes involved in the maintenance of BA homeostasis were analyzed in human hepatoma (HepG2) and colon carcinoma (Caco-2) cells, as well as in primary culture of human intestinal (InEpC) and renal (RPTEC) cells. Extracellular BA species were quantified in culture media using LC-MS/MS. BA-induced toxicity was evaluated using caspase-3 and flow cytometry assays. Gene expression analyses of HepG2 cells reveal that n-3 PUFAs reduce the expression of genes involved in BA synthesis (CYP7A1, CYP27A1) and uptake (NTCP), while activating genes encoding metabolic enzymes (SULT2A1) and excretion transporters (MRP2, MRP3). N-3 PUFAs also generate a less toxic BA pool and prevent the BA-dependent activation of apoptosis in HepG2 cells. Conclusion. The present study reveals that n-3 PUFAs stimulate BA detoxification

3D migration of cells solving an inverse problem

International audienceTraction Force Microscopy (TFM) is an inverse method that allows to obtain the stress field applied by a living cell on the environment on the basis of a pointwise knowledge of the displacement produced by the cell itself during its migration. This biophysical problem, usually addressed in terms of Green functions, can be alternatively tackled in a variational framework. In such a case, a suitable penalty functional has to be minimized. The resulting Euler-Lagrange equations include both the direct problem based on the linear elasticity operator as well as an equation built on its adjoint. Results from a two-dimensional model, i.e. where living cancer cells are migrating on a plane substrate, are briefly presented. While the mathematics is well established also in the three-dimensional case, i.e. where cells are completely embedded in the gel matrix, the experimental data needed are more difficult to obtain than the two-dimensional counterpart. First steps towards the complete three-dimensional traction reconstruction are reported

Mathematical framework for Traction Force Microscopy

International audienceThis paper deals with the Traction Force Microscopy (TFM) problem. It consists in obtaining stresses by solving an inverse problem in an elastic medium, from known experimentally measured displacements. In this article, the application is the determination of the stresses exerted by a living cell at the surface of an elastic gel. We propose an abstract framework which formulates this inverse problem as a constrained minimization problem. The mathematical constraints express the biomechanical conditions that the cell must satisfy. From this framework, two methods currently used can be derived, the adjoint method (AM) and the Fourier Transform Traction Cytometry (FTTC) method. An improvement of the FTTC method is also derived using this framework. The numerical results are compared and show the advantage of the AM, in particular it can capture details more accurately

Surgical treatment of subaortic stenosis after biventricular repair of double-outlet right ventricle

AbstractOut of 180 patients who underwent biventricular repair of double-outlet right ventricle between 1980 and 1995, 9 (5%) required reoperation because of subaortic stenosis. Two other patients who initially underwent operation elsewhere underwent reoperation at our institution because of subaortic stenosis. The median age at biventricular repair was 4 months. Repair consisted of tunnel construction from the left ventricle to the aorta in nine patients; the remaining two patients received an arterial switch operation with ventricular septal defect closure. Subaortic stenosis developed with time: the mean postoperative left ventricle–to–aorta gradient after repair was 10 ± 19 mm Hg (range, 0 to 50 mm Hg) and became 84 ± 27 mm Hg (range, 40 to 124 mm Hg) in a mean delay of 45 ± 66 months (range, 1 to 213 months). At reoperation, the obstruction was caused by the protrusion of the inferior rim of the ventricular septal defect into the left ventricular outflow tract associated with subaortic hypertrophied muscle and membrane. The 11 patients underwent 15 reoperations. Surgical technique consisted of an extended septoplasty in 6 reoperations. In this technique an incision was made in the septal patch and was extended into the muscle toward the apex until a large opening of the left ventricular outflow pathway was obtained. A new patch was then secured to streamline the left ventricular outflow tract. None of the patients who underwent extended septoplasty had to undergo reoperation. There were no early or late deaths. At 115 ± 85 months after biventricular repair, all patients were in New York Heart Association functional class I or II and the mean postoperative left ventricle–to–aorta gradient was 20 ± 24 mm Hg (range, 0 to 60 mm Hg). We conclude that after biventricular repair of double-outlet right ventricle, the subaortic region is at risk for the development of stenosis. Surgical treatment adapted to the anatomy of the obstruction can offer good early and midterm results. It seems that an aggressive approach by an extended septoplasty avoids multiple reoperations. (J Thorac Cardiovasc Surg 1996;112:1570-80

Specialized odorant receptors in social insects that detect cuticular hydrocarbon cues and candidate pheromones.

Eusocial insects use cuticular hydrocarbons as components of pheromones that mediate social behaviours, such as caste and nestmate recognition, and regulation of reproduction. In ants such as Harpegnathos saltator, the queen produces a pheromone which suppresses the development of workers' ovaries and if she is removed, workers can transition to a reproductive state known as gamergate. Here we functionally characterize a subfamily of odorant receptors (Ors) with a nine-exon gene structure that have undergone a massive expansion in ants and other eusocial insects. We deorphanize 22 representative members and find they can detect cuticular hydrocarbons from different ant castes, with one (HsOr263) that responds strongly to gamergate extract and a candidate queen pheromone component. After systematic testing with a diverse panel of hydrocarbons, we find that most Harpegnathos saltator Ors are narrowly tuned, suggesting that several receptors must contribute to detection and discrimination of different cuticular hydrocarbons important in mediating eusocial behaviour.Cuticular hydrocarbons (CHC) mediate the interactions between individuals in eusocial insects, but the sensory receptors for CHCs are unclear. Here the authors show that in ants such as H. saltator, the 9-exon subfamily of odorant receptors (HsOrs) responds to CHCs, and ectopic expression of HsOrs in Drosophila neurons imparts responsiveness to CHCs

How the cell got its shape : A visco-elasto-active model of the cytoskeleton

Living cells cytoskeleton is made of polymers which are constantly being re-modelled by polymerisation and depolymerisation, and which are bound to one another (crosslinked) through even more unstable molecules, lasting for about one second. With such a dynamic structure, one may wonder how cells can maintain a given shape over time ranges several orders of magnitude larger than the turn-over time of their constituents. We propose a rheological model which features crosslink turn-over, polymerisation and molecular motor-generated contractile forces, and provides answers to these questions