Antideuteron production in proton-proton and proton-nucleus collisions

The experimental data of the antideuteron production in proton-proton and proton-nucleus collisions are analyzed within a simple model based on the diagrammatic approach to the coalescence model. This model is shown to be able to reproduce most of existing data without any additional parameter.Comment: To appear in Eur. Phys. J A (2002

Synthesis of substituted tetrahydroisoquinolines by lithiation then electrophilic quench

Substituted N-tert-butoxycarbonyl (Boc)-1,2,3,4-tetrahydroisoquinolines were prepared and treated with n-butyllithium in THF at −50 °C to test the scope of the metallation and electrophilic quench. The lithiation was optimised by using in situ ReactIR spectroscopy and the rate of rotation of the carbamate was determined. The 1-lithiated intermediates could be trapped with a variety of electrophiles to give good yields of 1-substituted tetrahydroisoquinoline products. Treatment with acid or reduction with LiAlH4 allows conversion to the N–H or N–Me compound. The chemistry was applied to the efficient total syntheses of the alkaloids (±)-crispine A and (±)-dysoxyline

Endothelial cell regulation of leukocyte infiltration in inflammatory tissues

Endothelial cells play an important, active role in the onset and regulation of inflammatory and immune reactions. Through the production of chemokines they attract leukocytes and activate their adhesive receptors. This leads to the anchorage of leukocytes to the adhesive molecules expressed on the endothelial surface. Leukocyte adhesion to endothelial cells is frequently followed by their extravasation. The mechanisms which regulate the passage of leukocytes through endothelial clefts remain to be clarified. Many indirect data suggest that leukocytes might transfer signals to endothelial cells both through the release of active agents and adhesion to the endothelial cell surface. Adhesive molecules (such as PECAM) on the endothelial cell surface might also ‘direct’ leukocytes through the intercellular junction by haptotaxis. The information available on the molecular structure and functional properties of endothelial chemokines, adhesive molecules or junction organization is still fragmentary. Further work is needed to clarify how they interplay in regulating leukocyte infiltration into tissues

Laser-Assisted Cryosurgery in ex vivo Mice Hepatic Tissue: Viability Assays Using Green Fluorescent Protein

An experimental investigation is carried out to develop a novel approach to cryosurgery, where laser heating counteracts tissue freezing to better confine damage to the targeted cancerous tissue within a lethal low-temperature isothermal boundary—an approach we refer to as laser-assisted cryosurgery (LAC). The advantage of this procedure relative to conventional cryosurgery assisted with urethral warmers or cryoheaters is that laser heating provides volumetric rather than superficial heating, which leads to deeper penetration, more homogeneous tissue protection and better demarcation of the destructive freezing effect to a well-defined targeted volume. Tissue viability assays are performed using green fluorescence protein (GFP) as a viability marker and correlated with temperature history after performing LAC procedures on ex vivo mice hepatic tissue. The limit for cell denaturation at the irradiated surface predicted by GFP analysis is further confirmed using reverse transcription polymerase chain reaction (RT-PCR). In addition, the correlation between GFP fluorescence and cell viability and loss of GFP fluorescence in non-viable cells has been tested and validated by histological analysis using a standard cell viability measuring method (hematoxylin and eosin staining). Analysis of our experimental measurements show that reproducible thermal gradients (of 236 °C/cm) and predictable tissue necrosis can be reliably produced by LAC without exceeding temperature thresholds for cell denaturation (of Tsurf ≈ 48 °C) beyond preset tissue boundaries (with resolution of 0.1 °C/mm). The results have shown the feasibility of controlling temperatures at specified tissue locations to prevent hyperthermal or freezing damage

Nuclear DNA content in the subgenus Coffea (Rubiaceae) : inter and intra-specific variation in African species

La cytométrie en flux a été utilisée pour estimer la quantité d'ADN nucléaire chez 13 espèces de #Coffea (Rubiacea) originaires d'Afrique. Douze espèces diploïdes (#2n=22) et l'espèce tétraploïde #C. arabica (#2n=44) ont été analysées. Pour 77 génotypes, des populations de noyaux isolés ont été colorées par l'iodure de propidium (IP ; non spécifique des bases). Pour trente neuf génotypes, le 4',6-diamidino-2-phenylindole (DAPI; AT spécifique) a été également utilisé. Les quantités 2C d'ADN nucléaire, estimées avec l'IP, oscillent entre 0,95 et 1,78 pg. Trois groupes correspondant à des quantités croissantes d'ADN ont été mis en évidence. Les trois espèces #C. sessiliflora, C. racemosa et #C. pseudozanguebariae se classent dans le groupe des plus petites valeurs (groupe 1 : 0,90 à 1,30 pg). Les trois espèces #C. eugenioides, C. stenophylla et #C. sp. F. se rangent uniquement dans le groupe des valeurs intermédiaires (groupe 2 : 1,31 à 1,60 pg). Les autres espèces se répartissent entre le groupe 2 et le groupe des plus hautes valeurs (groupe 3 : 1,61 à 1,80 pg). Les valeurs déterminées pour les espèces de #Coffea$, sont comparées aux niveaux intra- et inter-spécifique à celles d'autres angiospermes. Les différences observées sont discutées en fonction de l'origine éco-géographique des espèces, leurs caractéristiques phénologiques et la fertilité de leurs hybrides F1 interspécifiques. (Résumé d'auteur

Atmospheric and Galactic Production and Propagation of Light Antimatter Nuclei

The production and propagation of light antimatter nuclei has been calculated using inclusive antiproton production cross sections from a new data analysis, and coalescence models for the production of composite particles. Particles were propagated using recently proven phenomenological approaches. The atmospheric secondary flux is evaluated for the first time. The Galactic flux obtained are larger than those obtained previously in similar calculations. The non-annihilating scattering contributions of the propagated particles are introduced. The preliminary results are shown and discussed.Comment: 4 pages, Contribution to the ICRC 200

HIV-1 VPR impairs cell growth through the inactivation of two genetically distinct host cell proteins

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Inflammatory response of endothelial cells to a human endogenous retrovirus associated with multiple sclerosis is mediated by TLR4.

The MSRV (multiple sclerosis-associated retrovirus) belongs to the human endogenous retrovirus HERV-W family. The envelope protein originating from the MSRV has been found in most patients with multiple sclerosis (MS). This protein (Env-ms) has pro-inflammatory properties for several types of immune cells and could therefore play a role in MS pathogenesis by promoting the leukocyte diapedesis observed in the central nervous system of patients. Our study aims to analyze the effects of Env-ms on the blood-brain barrier (BBB) at a molecular and functional level. We demonstrate that the recombinant MSRV envelope is able to stimulate several inflammatory parameters in a human BBB in vitro model, the HCMEC/D3 brain endothelial cell line. Indeed, Env-ms induces over-expression of ICAM-1, a major mediator of leukocyte adhesion to endothelial cells, in a dose-dependent manner as well as a strong dose-dependent production of the pro-inflammatory cytokines IL-6 and IL-8. Furthermore, using a silencing approach with siRNAs, we show that Env-ms is recognized via the Toll-like receptor 4 receptor, a pattern recognition receptor of innate immunity present on endothelial cells. We also show, using functional assays, that treatment of brain endothelial cells with Env-ms significantly stimulated the adhesion and the transmigration of activated immune cells through a monolayer of endothelial cells. These findings support the hypothesis that MSRV could be involved in the pathogenesis of MS disease or at least in maintenance of inflammatory conditions, thus fueling the auto-immune disorder. MSRV could also play a role in other chronic inflammatory diseases

General Analysis of Antideuteron Searches for Dark Matter

Low energy cosmic ray antideuterons provide a unique low background channel for indirect detection of dark matter. We compute the cosmic ray flux of antideuterons from hadronic annihilations of dark matter for various Standard Model final states and determine the mass reach of two future experiments (AMS-02 and GAPS) designed to greatly increase the sensitivity of antideuteron detection over current bounds. We consider generic models of scalar, fermion, and massive vector bosons as thermal dark matter, describe their basic features relevant to direct and indirect detection, and discuss the implications of direct detection bounds on models of dark matter as a thermal relic. We also consider specific dark matter candidates and assess their potential for detection via antideuterons from their hadronic annihilation channels. Since the dark matter mass reach of the GAPS experiment can be well above 100 GeV, we find that antideuterons can be a good indirect detection channel for a variety of thermal relic electroweak scale dark matter candidates, even when the rate for direct detection is highly suppressed.Comment: 44 pages, 15 Figure