Search results for "58"
showing 10 items of 2229 documents
Circulating markers of retinal and optic nerve lipids
2013
Purpose Blood lipids are frequently used as a surrogate of lipid composition of peripheral tissues. Even if it is well accepted, such a relationship has never been clearly demonstrated for the eye. The aim of this study was to determine in human samples whether a lipidomic approach based on red blood cells could reveal associations between circulating and ocular lipid profiles. Methods Red blood cells, retinas and optic nerves were collected from 9 human donors. The lipidomic analyses on these tissues were done by both, gas chromatography and liquid chromatography coupled to an electrospray ionization source-mass spectrometer (LC-ESI-MS/MS). Results Gas chromatographic approach did not show…
Covarying shell growth parameters and the regulation of shell shape in marine bivalves: a case study on Tellinoidea.
2014
Specific parameters characterising shell shape may arguably have a significant role in the adaptation of bivalve molluscs to their particular environments. Yet, suchfunctionally relevantshape parameters (shell outline elongation, dissymmetry, and ventral convexity) are not those parameters that the animal may directly control. Rather than shell shape, the animal regulates shell growth. Accordingly, an alternative,growth-baseddescription of shell-shape is best fitted to understand how the animal may control the achieved shell shape. The key point is, in practice, to bring out the link between those two alternative modes of shell-shape descriptions, that is, to derive the set of equations whi…
Near-field observation of subwavelength confinement of photoluminescence by a photonic crystal microcavity
2006
We present a direct, room-temperature near-field optical study of light confinement by a subwavelength defect microcavity in a photonic crystal slab containing quantum-well sources. The observations are compared with three-dimensional finite-difference time-domain calculations, and excellent agreement is found. Moreover, we use a subwavelength cavity to study the influence of a near-field probe on the imaging of localized optical modes. © 2006 Optical Society of America.
Evaluation agroécologique de systèmes de culture en zone tropicale humide : Cas de la mise en valeur agricole d'une savane herbacée acide (Plaine des…
2013
Dans les régions tropicales humides, concilier intensification agricole et protection des ressources naturelles est un défi majeur et difficile à relever. Dans les savanes acides du nord-est laotien, des systèmes de culture de semis direct sur couverture végétale (SCV), basés sur les trois principes du non-labour, d’une couverture permanente du sol, et sur la pratique de rotations culturales diversifiées, sont proposés comme alternative technique à l’intensification agricole conventionnelle basée sur le labour. Si ces systèmes ont connu une diffusion importante et rapide dans les grandes agricultures mécanisées, leur diffusion reste néanmoins à ce jour limitée en contexte de petite agricult…
Involvement of plasmalogens and iPLA2 in the control of post-natal retinal vascular development in mice
2014
International audience; Purpose: The correct development of retinal blood vessels is essential to ensure vision process through sufficient oxygen and nutrient supplies to the retina. It was shown that polyunsaturated fatty acids (PUFAs) could modulate factors involved in tissue vascularization. A congenital deficiency in ether-phospholipids also termed as "plasmalogens" was shown to lead to abnormal ocular vascularization. Because plasmalogens are considered as reservoirs of PUFAs, we wanted to better understand the mechanisms by which plasmalogens may regulate retinal vascular development through the release of PUFAs by a calcium-independent phospholipase A2 (iPLA2). Methods: Retinal vascu…
Dietary ω3 fatty acids & metabolic syndrome in the rat: consequences on sensitivity and retinal functionality
2014
International audience; Purpose: High fructose diets have been widely used to trigger metabolic syndrome (MetS) in rodents. Insulin resistance is a major risk factor for the development of type 2 diabetes leading in 30 to 40% of the cases to the development of diabetic retinopathy in humans. In the other hand, ω3 fatty acids have been associated with the prevention of MetS. Few studies have been interested in the early changes occurring in the retina after induction of MetS and to potential of ω3 fatty acids to reverse those effects. Methods: 96 male Brown Norway rats (6 weeks of age) were fed for 3 and 8 days with either of the four following diets (n=8 in each group): a regular chow diet …
The relevance of the French rural policy by the yardstick of the theories of justice
2010
The relevance of the French rural policy by the yardstick of the theories of justice How to evaluate the relevance of the French rural policy ? When the question is to what extent the objectives of the policy are reached owing to public interventions, the method is relatively well known. However, when the question is to what extent these objectives are relevant, an important problem is faced : the referential of this evaluation is indefinite. In this article, we propose to define this referential on the basis of moral and political philosophy : The objectives are relevant if they are derived from a conception of justice that is itself relevant. From this viewpoint, the relevance of the curr…
Polyunsaturated fatty acids and plasmalogens in diabetics
2013
PurposePlasmalogens are phospholipids characterized by a vinyl ether bond and a preferential esterification of polyunsaturated fatty acids (PUFA). We have previously shown that the lack of plasmalogens leads to retinal hyper-capillarization. We hypothesize that plasmalogens are negative regulators of vascular development, and aimed to check their circulating levels in diabetic patients with a retinopathy. MethodsBlood samples were collected from 88 patients and 14 control subjects. Among diabetics we had 14 patients without diabetic retinopathy (DR), 12 with a mild non proliferative DR, 12 with a moderate non proliferative DR, 22 with a severe non proliferative DR and 24 with a proliferativ…
Effect of Endomycorrhizal Infection on Root System Development in the Apple Rootstock (Malus domestica Borkh.) M26
1994
A mycorrhizal fungus (Glomus intraradices) is able to promote shoot growth of the apple rootstock M26. We have shown that the root system is also modified by the presence of the endophyte. Mycorrhiza formation reduced the shoot to root ratio and increased the specific root length. We show that in apple modifications in root architecture are mainly due to a reduction in the elongation of the different root orders.
Enseigner l’activité « écriture collaborative »
2019
Although certain education policies emphasize “the ability to collaborate” as a key element of educational reform, education for digital collaboration is poorly supported by public schools. To build the conditions of a sustainable education, we have developed a training model focused on learner autonomy. We present the results of an experiment conducted with students, our pedagogical model and its implementation, as well as our observation and analysis of this experiment. We analyzed discussions in instant messaging between students and teachers, and their productions. All results show the influence of our training. Thus, education and digital collaboration can be built from a triple analyt…