Elaboration de surfaces nano/micro-structurées pour limiter l’adhésion de micro-organismes

Avec plus d’un million de dispositifs posés par an dans le monde, l’utilisation des chambres implantables s’est maintenant généralisée pour le traitement de certains cancers. Constituées d’un réservoir de quelques dixièmes de microlitres, le plus souvent en titane, relié à un cathéter dont l’extrémité est placée dans une veine à fort débit, ils permettent de délivrer un traitement de chimiothérapie avec un confort augmenté pour le patient. Ces dispositifs permettent aussi le cas échéant d’apporter une nutrition parentérale. Cette dernière utilisation provoque de nombreuses infections, qui conduisent dans la plupart des cas au retrait du dispositif. Afin de réduire le risque de contamination, il est donc nécessaire de mieux comprendre les facteurs favorisant l’adhérence des micro-organismes (bactéries et levures) dans ces dispositifs médicaux invasifs et leur colonisation ultérieure. Dans le cadre du projet régional MAT-INNO, nos travaux de recherche visent à mieux comprendre l’impact des propriétés de surface (en termes de topographie, hydrophobicité et fonctionnalisation) sur l’adhésion de bactéries et de levures. En agissant sur les propriétés physiques et/ou chimiques de surface, nous espérons réduire les capacités d\u27adhérence des micro-organismes et ainsi limiter le risque d\u27infection. Les études actuelles sont réalisées sur des substrats de silicium sur lesquels est déposée une couche mince nanométrique d’oxyde de titane. Nos efforts portent, dans un premier temps, sur la maîtrise de la topographie de surface à l’échelle nanométrique et micrométrique, notamment par la mise au point de procédés de fabrication reproductibles. L’utilisation de la pulvérisation cathodique sur les supports de silicium ultra-lisses permet d’obtenir des surfaces d’oxyde de titane ayant des rugosités inférieures au nanomètre. De plus, l’attaque du silicium par l’hydroxyde de potassium permet de modifier la topographie des surfaces avant le dépôt de films minces d’oxyde de titane. Nous présentons sur le poster les résultats obtenus récemment par microscopie à force atomique et par microscopie électronique à balayage sur les différents types de surface. L’analyse des courbes de réflectivité des rayons X nous a permis de déterminer précisément l’épaisseur des films déposés et de suivre les modifications de la composition chimique suivant les paramètres appliqués

Electron beam total skin irradiation

Total skin low energy electron irradiation (TSEI) remains one of the most effective modes of treatment for generalized superficial lesions. After a brief review of the irradiation beam requirements (treatment of the first few milimeters of skin, uniformity of dose distribution in spite of variations in the shape and size of patients) and the different irradiation methods, the autors present the technique used at Henri Mondor hospital and some other french centers. It consist of 3 vertical adjacent fields with patient lying alternatively in prone then supine position. An custome-made lucite scattering screen used together with incident electran beams of 7–9 MeV provides an homogenous dose distribution in patient's parts of large radius of curvature.The dosimetric study performed essentially with TLD dosimeters and films has shown that the lucite screen was the best choice because its transparency makes easier patient positionning and it induces a very low X-ray contamination. It also shown that the screen has to be set close to the patient both to increase the skin dose and to keep an acceptable dose-rate at the patient's level.Besides experiments performed with a semi-infinite fiat phantom made of equivalent-tissue material and an Alderson Rando phantom simulating the human body, experiments were carried out with layered flat phantoms of small thicknesses and cylindrical phantoms (radii varying from 1 to 9 cm) simulating hand and lower limb cross sections. Results obtained at 4 MeV (mean energy at the patient's surface) have shown that the overdosage in anatomical structure of large radius of curvature but small thickness (palme of hands) is 200% of the prescribed dose for 1 cm thickness, 160% for 2 cm and becomes normal for thicknesses ≥3 cm. Large variations of dose have also been measured in cylindical phantoms simulating fingers, ankle or wrist. They depend on both the radius of the structure and the incidence angle of the beam at the skin surface. Some examples are presented.Such results confirmed by in vivo measurements can explain the complications in anatomical regions of small radii of curvature and/or small thickness (erythematous skin, swelling of feet, ankles and hands) reported by different authors. It is the reason why shields for the hands or feet have to be provided well before the full course of therapy is completed, and thus irrespective of the irradiation technique used

Elaboration et évaluation d'algorithmes de dépistage des MST chez la femme enceinte à Libreville, Gabon

La lutte contre les MST constitue une priorité de santé publique des pays en développement de par leurs complications propres, en particulier chez la femme, et de par leur rôle facilitant la transmission du VIH. Une des stratégies de lutte contre les MST est le diagnostic et le traitement précoces de ces infections. Les MST, en particulier les infections à gonocoques et à #Chlamydiae trachomatis$sont d'un diagnostic difficile chez la femme en l'absence d'examens complémentaires, ceux-ci faisant souvent défaut au niveau des structures de soins de santé primaire. Dans ce contexte, l'approche syndromique, basée sur la prise en compte de signes et symptômes, peut permettre de standardiser et d'améliorer la prise en charge des patientes. Une étude de prévalence et de facteurs de risque des MST, effectuées chez 192 femmes enceintes consultant en PMI à Libreville (Gabon), en septembre 1993, a confirmé la prévalence des MST dans cette population (13,5$). L'évaluation de différentes stratégies diagnostiques et d'algorithmes montre que, quel que soit le niveau d'examen (données d'interrogatoire, examen clinique simple, examen au spéculum), l'utilisation de scores intégrant des facteurs de risque, des symptômes et des signes cliniques est plus performante que les algorithmes hiérarchiques. Ces scores présentent des sensibilités et des spécificités élevées et sont d'une mise en oeuvre facile. Leur application pourrait donc permettre le dépistage efficace des MST et éviter, ainsi, une grande partie des complications maternelles et infantiles. (Résumé d'auteur

Isolation of Trichophyton concentricum from chronic cutaneous lesions in patients from the Solomon Islands

Tinea imbricata, also known as ‘Tokelau’, is an uncommon superficial mycosis caused by the anthropophilic dermatophyte Trichophyton concentricum. Cutaneous lesions appear characteristically as scaly and concentric rings that may cover all parts of the body. Often acquired in childhood, tinea imbricata is a chronic disease and lichenification is extremely common due to pruritus. The dermatophytosis mainly occurs in the South Pacific, but also in some regions of Southeast Asia and Central or South America. Tinea imbricata usually affects people living in primitive and isolated conditions. Mycological analysis is required for the diagnosis. The epidemiological and mycological study reported here took place in the Solomon Islands from June–September 2006. Skin scrapings were collected from 29 Melanesian patients (aged 8 months to 58 years) with chronic cutaneous lesions and were analysed mycologically in the Laboratory of Parasitology and Mycology of Angers University Hospital (France). Ten patients showed very evocative lesions with a positive direct examination, but T. concentricum was only isolated from three patients. Identification of the strains was confirmed by sequencing of the internal transcribed spacer (ITS) regions. With the increase in international travel, one cannot disregard that this very rare species may be isolated by mycologists in temperate areas from patients coming from endemic foci

Synapse efficiency diverges due to synaptic pruning following over-growth

In the development of the brain, it is known that synapses are pruned following over-growth. This pruning following over-growth seems to be a universal phenomenon that occurs in almost all areas -- visual cortex, motor area, association area, and so on. It has been shown numerically that the synapse efficiency is increased by systematic deletion. We discuss the synapse efficiency to evaluate the effect of pruning following over-growth, and analytically show that the synapse efficiency diverges as O(log c) at the limit where connecting rate c is extremely small. Under a fixed synapse number criterion, the optimal connecting rate, which maximize memory performance, exists.Comment: 15 pages, 16 figure

Alignment of the CMS silicon tracker during commissioning with cosmic rays

This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe CMS silicon tracker, consisting of 1440 silicon pixel and 15 148 silicon strip detector modules, has been aligned using more than three million cosmic ray charged particles, with additional information from optical surveys. The positions of the modules were determined with respect to cosmic ray trajectories to an average precision of 3–4 microns RMS in the barrel and 3–14 microns RMS in the endcap in the most sensitive coordinate. The results have been validated by several studies, including laser beam cross-checks, track fit self-consistency, track residuals in overlapping module regions, and track parameter resolution, and are compared with predictions obtained from simulation. Correlated systematic effects have been investigated. The track parameter resolutions obtained with this alignment are close to the design performance.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Commissioning and performance of the CMS pixel tracker with cosmic ray muons

This is the Pre-print version of the Article. The official published verion of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe pixel detector of the Compact Muon Solenoid experiment consists of three barrel layers and two disks for each endcap. The detector was installed in summer 2008, commissioned with charge injections, and operated in the 3.8 T magnetic field during cosmic ray data taking. This paper reports on the first running experience and presents results on the pixel tracker performance, which are found to be in line with the design specifications of this detector. The transverse impact parameter resolution measured in a sample of high momentum muons is 18 microns.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)