Développement d'une méthode de reconstruction d'image basée sur la détection de la fluorescence X pour l'analyse d'échantillon

A new technique that localizes and identifies fluorescing elements in a sample wasdeveloped. This practical imaging modality employs a polychromatic X-ray source toirradiate the sample and prompts the fluorescence emission. Many factors affecting thewhole system like attenuation, sample self-absorption, probability of fluorescence andCompton scattering were taken into account. Then, an effective detection system wasestablished to acquire the optimum fluorescence data and discriminate betweenelements depending on their characteristic fluorescence. This set-up, coupled with anappropriate image reconstruction technique leads to a detailed two-dimensional image.Compared to the conventional image reconstruction techniques, the developedreconstruction method is a statistical technique and has an appropriate convergencetoward an image with acceptable resolution. Moreover, it is a simplified technique thatallows the imaging of many different applications.Une nouvelle technique qui localise et identifie les éléments fluorescents dans un échantillon a été développé. Cette modalité d'imagerie pratique utilise une source de rayons X poly-chromatique pour irradier l'échantillon et favoriser l'émission de fluorescence. De nombreux facteurs qui affectent l'ensemble du système comme l'atténuation, l'auto-absorption de l'échantillon, la probabilité de fluorescence et la diffusion Compton ont été pris en compte. Ensuite, un système de détection efficace a été établi pour acquérir les données de fluorescence optimales et discriminer entre les éléments en fonction de leur fluorescence caractéristiques. Ce dispositif, couplé avec une technique de reconstruction d'image approprié conduit à une image détaillée à deux dimensions. Par rapport aux techniques classiques de reconstruction d'image, la méthode de reconstruction développée est une technique statistique qui a une convergence appropriée vers une image avec une résolution acceptable. En outre, c'est une technique simplifiée qui permet l'imagerie de nombreuses applications différentes

Superficialization of arteriovenous fistulae employing minimally invasive liposuction

Superficialization of arteriovenous fistulae allows for improved dialysis access allowing for prolonged utilization and more efficient dialysis treatment. Multiple methods are described for superficializing arteriovenous fistulae, and minimizing the surgical intervention is advantageous for patient recovery and potentially improved outcomes. We describe a novel technique of superficialization of an upper extremity arteriovenous fistula employing ultrasound-guided liposuction. This article describes the suction lipectomy technique and the tools necessary for superficialization of an upper extremity arteriovenous fistula

Negative Regulation of FcεRI-mediated Degranulation by CD81

Signaling through the high affinity receptor for immunoglobulin E (FcεRI) results in the coordinate activation of tyrosine kinases before calcium mobilization. Receptors capable of interfering with the signaling of antigen receptors, such as FcεRI, recruit tyrosine and inositol phosphatases that results in diminished calcium mobilization. Here, we show that antibodies recognizing CD81 inhibit FcεRI-mediated mast cell degranulation but, surprisingly, without affecting aggregation-dependent tyrosine phosphorylation, calcium mobilization, or leukotriene synthesis. Furthermore, CD81 antibodies also inhibit mast cell degranulation in vivo as measured by reduced passive cutaneous anaphylaxis responses. These results reveal an unsuspected calcium-independent pathway of antigen receptor regulation, which is accessible to engagement by membrane proteins and on which novel therapeutic approaches to allergic diseases could be based

RBL cells as models for in vitro studies of mast cells and basophils

Since their establishment in 1981, RBL-2H3 cells have been widely used as a mast cell (MC) model. Their ability to be easily grown in culture in large amounts, their responsiveness to FcεRI-mediated triggers and the fact that they can be genetically manipulated,have provided advantages over primary MCs, in particular for molecular studies relying on genetic screening. Furthermore, the ability to generate clones that stably express proteins of interest, for example, a human receptor, have marked the RBL cells as an attractive MC model for drug screening. Indeed, 3 RBL reporter cell lines (RS-ATL8, NFAT-DsRed,and NPY-mRFP) have been generated providing useful models for drug and allergen screening. Similarly, RBL cells stably expressing the human MrgprX2 receptor provide a unique paradigm for analyzing ligand interactions and signaling pathways of the unique human receptor. Finally, transient co-transfections of RBL cells allow functional genomic analyses of MC secretion by combining library screening with simultaneous expression of a reporter for exocytosis. RBL cells thus comprise powerful tools for the study of intracellular membrane trafficking and exocytosis and the detection of allergens, vaccine safety studies and diagnosis of allergic sensitization. Their recent uses as an investigative tool are reviewed here

Antigen induced modulation of autonomic nervous system responses in immunoglobulin-E - sensitized rabbit lung.

The major objective of this project was to examine the potential for mediators of IgE-mediated allergic reactions to alter neural activity. The project was divided into three parts. In Part I, the ability of endogenously released chemical mediators to alter neural activity in vitro was assessed by measuring isometric contractile responses to electrical field stimulation (EFS) (2-128 Hz, 20 V, 0.5 msec. duration) of sensitized rabbit bronchi before and after exposure to the antigen horseradish peroxidase (HRP). Antigen enhanced bronchial responses to EFS with low frequencies: mean log (± S.E.) frequency which produced 20% of maximum response decreased from 1.04 (± 0.05) to 0.90 (± 0.07) Hz (p < 0.05). Responses of unsensitized bronchi were not enhanced by antigen. Chlorpheniramine, an H₁ antagonist, abolished the antigen effect. Antigen did not enhance the responses to exogenous acetylcholine. Hence, the antigen is apparently modulating neural activity and not smooth muscle per se. In Part II, the capacity for histamine to modulate vagally-induced bronchoconstriction in anesthetized, vagotomized, mechanically-ventilated rabbits was examined in vivo. Changes in pulmonary resistance induced by electrically stimulating the cut ends of the vagi (2-32 Hz, 20 V, 0.5 msec. duration) were assessed before and 10 minutes after histamine aerosolization (10 breaths of 10 mg/ml). Histamine inhalation potentiated vagally-induced bronchoconstriction at low frequencies: mean log (± S.E.) frequency producing a 20% change in pulmonary resistance decreased from 0.88 (± 0.09) to 0.56 (± 0.15) (p < 0.05). Chlorpheniramine abolished this effect. In Part III, the dependence on IgE antibodies of the in vitro modulation of neurally-induced contraction of sensitized bronchi was investigated. Rabbits were passively immunized with fractions enriched with HRP-specific IgE, IgG, or IgM antibodies. After 72 hours, rabbits were sacrificed and the responses of bronchi to EFS were assessed before and after antigen challenge. Antigen enhanced the responses to EFS only of bronchi passively sensitized with IgE. Therefore, antigen enhancement of neural activity was dependent on IgE. These studies demonstrate that the interaction between antigen and IgE antibodies can induce the release of chemical mediators which can alter neural activity

Development of an image reconstruction method based on the detected X-ray fluorescence for sample analysis

Une nouvelle technique qui localise et identifie les éléments fluorescents dans un échantillon a été développé. Cette modalité d'imagerie pratique utilise une source de rayons X poly-chromatique pour irradier l'échantillon et favoriser l'émission de fluorescence. De nombreux facteurs qui affectent l'ensemble du système comme l'atténuation, l'auto-absorption de l'échantillon, la probabilité de fluorescence et la diffusion Compton ont été pris en compte. Ensuite, un système de détection efficace a été établi pour acquérir les données de fluorescence optimales et discriminer entre les éléments en fonction de leur fluorescence caractéristiques. Ce dispositif, couplé avec une technique de reconstruction d'image approprié conduit à une image détaillée à deux dimensions. Par rapport aux techniques classiques de reconstruction d'image, la méthode de reconstruction développée est une technique statistique qui a une convergence appropriée vers une image avec une résolution acceptable. En outre, c'est une technique simplifiée qui permet l'imagerie de nombreuses applications différentes.A new technique that localizes and identifies fluorescing elements in a sample wasdeveloped. This practical imaging modality employs a polychromatic X-ray source toirradiate the sample and prompts the fluorescence emission. Many factors affecting thewhole system like attenuation, sample self-absorption, probability of fluorescence andCompton scattering were taken into account. Then, an effective detection system wasestablished to acquire the optimum fluorescence data and discriminate betweenelements depending on their characteristic fluorescence. This set-up, coupled with anappropriate image reconstruction technique leads to a detailed two-dimensional image.Compared to the conventional image reconstruction techniques, the developedreconstruction method is a statistical technique and has an appropriate convergencetoward an image with acceptable resolution. Moreover, it is a simplified technique thatallows the imaging of many different applications

Die Bewertung und Verwaltung von Auslandsinvestitionen in Entwicklungslaendern: unter bes. Beruecks. d. Beispiels Aegypten

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