Atelier thématique: Conversion de rasters en vecteurs

Nous avons accès à des cartes thématiques diverses au format image, (cartes pédologiques par ex.). Celles-ci sont des sources d’information très intéressantes car elles permettraient si nous pouvions les importer, d’exploiter leurs données comme s’il s’agissait d’une couche vectorielle, et croiser leurs informations avec des mesures. Cependant, ces images sont très hétérogènes : aux formats variés (jpeg, pdf, etc.), souvent issues de scan (résolution, qualité), complexes (nombreuses classes d’objet) et sur des aires géographiques étendues (région, bassin versant, etc.). L’idée est donc de les vectoriser pour les reproduire à l’identique, mais dans un format plus exploitable. Il existe trois méthodes de difficulté et de chronophagie croissante : 1°) la vectorisation automatique ou conversion raster-vecteur ou polygonisation 2°) le dessin vectoriel ou digitalisation 3°) l’analyse d’image orientée-objet ou segmentation orientée obje

Optical imaging of luminescence for in vivo quantification of gene electrotransfer in mouse muscle and knee

BACKGROUND: Optical imaging is an attractive non-invasive way to evaluate the expression of a transferred DNA, mainly thanks to its lower cost and ease of realization. In this study optical imaging was evaluated for monitoring and quantification of the mouse knee joint and tibial cranial muscle electrotransfer of a luciferase encoding plasmid. Optical imaging was applied to study the kinetics of luciferase expression in both tissues. RESULTS: The substrate of luciferase (luciferin) was injected either intraperitonealy (i.p.) or in situ into the muscle or the knee joint. Luminescence resulting from the luciferase-luciferin reaction was measured in vivo with a cooled CCD camera and/or in vitro on tissue lysate. Maximal luminescence of the knee joint and muscle after i.p. (2.5 mg) or local injection of luciferin (50 μg in the knee joint, 100 μg in the muscle) were highly correlated. With the local injection procedure adopted, in vivo and in vitro luminescences measured on the same muscles significantly correlated. Luminescence measurements were reproducible and the signal level was proportional to the amount of plasmid injected. In vivo luciferase activity in the electrotransfered knee joint was detected for two weeks. Intramuscular electrotransfer of 0.3 or 3 μg of plasmid led to stable luciferase expression for 62 days, whereas injecting 30 μg of plasmid resulted in a drop of luminescence three weeks after electrotransfer. These decreases were partially associated with the development of an immune response. CONCLUSION: A particular advantage of the i.p. injection of substrate is a widespread distribution at luciferase production sites. We have also highlighted advantages of local injection as a more sensitive detection method with reduced substrate consumption. Besides, this route of injection is relatively free of uncontrolled parameters, such as diffusion to the target organ, crossing of biological barriers and evidencing variations in local enzymatic kinetics, probably related to the reaction medium in the targeted organ. Optical imaging was shown to be a sensitive and relevant technique to quantify variations of luciferase activity in vivo. Further evaluation of the effective amount of luciferase in a given tissue by in vivo optical imaging relies on conditions of the enzymatic reaction and light absorption and presently requires in vitro calibration for each targeted organ

cDNA Immunization of Mice with Human Thyroglobulin Generates Both Humoral and T Cell Responses: A Novel Model of Thyroid Autoimmunity

Thyroglobulin (Tg) represents one of the largest known self-antigens involved in autoimmunity. Numerous studies have implicated it in triggering and perpetuating the autoimmune response in autoimmune thyroid diseases (AITD). Indeed, traditional models of autoimmune thyroid disease, experimental autoimmune thyroiditis (EAT), are generated by immunizing mice with thyroglobulin protein in conjunction with an adjuvant, or by high repeated doses of Tg alone, without adjuvant. These extant models are limited in their experimental flexibility, i.e. the ability to make modifications to the Tg used in immunizations. In this study, we have immunized mice with a plasmid cDNA encoding the full-length human Tg (hTG) protein, in order to generate a model of Hashimoto's thyroiditis which is closer to the human disease and does not require adjuvants to breakdown tolerance. Human thyroglobulin cDNA was injected and subsequently electroporated into skeletal muscle using a square wave generator. Following hTg cDNA immunizations, the mice developed both B and T cell responses to Tg, albeit with no evidence of lymphocytic infiltration of the thyroid. This novel model will afford investigators the means to test various hypotheses which were unavailable with the previous EAT models, specifically the effects of hTg sequence variations on the induction of thyroiditis

Placental Growth Factor Contributes to Micro-Vascular Abnormalization and Blood-Retinal Barrier Breakdown in Diabetic Retinopathy

OBJECTIVE: There are controversies regarding the pro-angiogenic activity of placental growth factor (PGF) in diabetic retinopathy (DR). For a better understanding of its role on the retina, we have evaluated the effect of a sustained PGF over-expression in rat ocular media, using ciliary muscle electrotransfer (ET) of a plasmid encoding rat PGF-1 (pVAX2-rPGF-1). MATERIALS AND METHODS: pVAX2-rPGF-1 ET in the ciliary muscle (200 V/cm) was achieved in non diabetic and diabetic rat eyes. Control eyes received saline or naked plasmid ET. Clinical follow up was carried out over three months using slit lamp examination and fluorescein angiography. After the control of rPGF-1 expression, PGF-induced effects on retinal vasculature and on the blood-external barrier were evaluated respectively by lectin and occludin staining on flat-mounts. Ocular structures were visualized through histological analysis. RESULTS: After fifteen days of rPGF-1 over-expression in normal eyes, tortuous and dilated capillaries were observed. At one month, microaneurysms and moderate vascular sprouts were detected in mid retinal periphery in vivo and on retinal flat-mounts. At later stages, retinal pigmented epithelial cells demonstrated morphological abnormalities and junction ruptures. In diabetic retinas, PGF expression rose between 2 and 5 months, and, one month after ET, rPGF-1 over-expression induced glial activation and proliferation. CONCLUSION: This is the first demonstration that sustained intraocular PGF production induces vascular and retinal changes similar to those observed in the early stages of diabetic retinopathy. PGF and its receptor Flt-1 may therefore be looked upon as a potential regulatory target at this stage of the disease

Noninvasive biophotonic imaging for studies of infectious disease

According to World Health Organization estimates, infectious organisms are responsible for approximately one in four deaths worldwide. Animal models play an essential role in the development of vaccines and therapeutic agents but large numbers of animals are required to obtain quantitative microbiological data by tissue sampling. Biophotonic imaging (BPI) is a highly sensitive, nontoxic technique based on the detection of visible light, produced by luciferase-catalysed reactions (bioluminescence) or by excitation of fluorescent molecules, using sensitive photon detectors. The development of bioluminescent/fluorescent microorganisms therefore allows the real-time noninvasive detection of microorganisms within intact living animals. Multiple imaging of the same animal throughout an experiment allows disease progression to be followed with extreme accuracy, reducing the number of animals required to yield statistically meaningful data. In the study of infectious disease, the use of BPI is becoming widespread due to the novel insights it can provide into established models, as well as the impact of the technique on two of the guiding principles of using animals in research, namely reduction and refinement. Here, we review the technology of BPI, from the instrumentation through to the generation of a photonic signal, and illustrate how the technique is shedding light on infection dynamics in vivo

Échographie clinique par le médecin généraliste en soins primaires : état des lieux en Normandie, étude quantitative transversale

La pratique de l'échographie tend à se développer dans les cabinets des médecins généralistes. C'est dans ce contexte que cette étude a été réalisée ; l'objectif principal était de dresser un état des lieux de l'utilisation de cette technique d'imagerie en soins primaires en Normandie. Pour cela, nous avons utilisé une étude descriptive transversale par le biais d'un questionnaire adressé aux médecins généralistes de cette région. Des 8,3% des praticiens utilisant l'échographie, tous reconnaissent une amélioration du diagnostic, de la thérapeutique, et une meilleure orientation du patient dans leur pratique quotidienne. Elle est le prolongement de leur examen clinique. Quant aux 91,7% des médecins généralistes ne pratiquant pas cette imagerie, les principaux freins mis en avant sont une formation peu accessible, une responsabilité médico légale mise en jeu, ou encore un caractère chronophage trop important. Cependant, malgré ces réticences, la pratique de l'échographie semble intéressée de plus en plus de médecins généralistes. Quelle sera sa place dans leurs pratiques dans les années à venir

Thérapie génique non virale de variants du gène du récepteur soluble de type I du TNF-a [alpha] humain (application à différents modèles de pathologies inflammatoires)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF