Bacterium of one thousand and one variants: genetic diversity of Neisseria gonorrhoeae pathogenicity

The bacterium Neisseria gonorrhoeae causes the sexually transmitted infection gonorrhoea. Although diverse clinical manifestations are associated with gonorrhoea, ranging from asymptomatic through to localized and disseminated infection, very little is known about the bacterial determinants implicated in causing such different clinical symptoms. In particular, virulence factors, although defined and investigated in particular strains, often lack comprehensive analysis of their genetic diversity and how this relates to particular disease states. This review examines the clinical manifestations of gonorrhoea and discusses them in relation to disease severity and association with expression of particular virulence factors including PorB, lipooligosaccharide (LOS) and Opa, both in terms of their mechanisms of action and inter- and intra-strain variation. Particular attention is paid to phase variation as a key mechanism of genetic variation in the gonococcus and the impact of this during infection. We describe how whole-genome-sequence-based approaches that focus on virulence factors can be employed for vaccine development and discuss whether whole-genome-sequence data can be used to predict the severity of gonococcal infection

Proba opisu zaleznosci mechanicznych wlasciwosci zdzbel wybranych odmian pszenzyta od ich wilgotnosci

The stalks of three tritricale varieties, in milk maturity stage, were tested. Moisture content and three mechanical properties of the stalks were measured using ultrasound and biometric tests. Statistical processing of test results indicated strong correlation between stalk moisture content and its mechanical properties. The relationships between these items were described with square and cube polynomials. These equations indicate the presence of two special ranges of moisture content: one (w = 25÷30%), were the stalks show the minimum values of subject properties; and the other (w = 65÷80%), in which the stalks reach maximum values of these properties.W wyniku pomiarów ultradźwiękowych i biometrycznych wyznaczono wilgotność źdźbła oraz trzy cechy charakteryzujące jego własności mechaniczne. Pomiary prowadzono na trzech odmianach pszenżyta w dojrzałości mlecznej. Drogą aproksymacji średniokwadratowej dobrano równania opisujące związki między badanymi cechami a wilgotnością źdźbła

Le nanodiamant hydrogéné comme radiosensibilisant : investigations chimiques et physiques des mécanismes impliqués

Among all nanocarbons, detonation nanodiamonds (NDs) possess outstanding chemical and physical properties suitable for bio-applications. Well-controlled mass production provides NDs with a primary size of 5 nm made of a diamond-core and a shell-coating containing various surface terminations. Surface chemistry of NDs can be tuned via thermal or plasma treatments providing either positively or negatively charged NDs in water suspension. Our group recently showed that plasma hydrogenated NDs (H-NDs) behave a radiosensitizing effect on radioresistant cancer cell lines providing potential therapeutic abilities as radiosensitizing agents. Nevertheless, the mechanisms involved behind this effect are not currently well understood. The main goal of this PhD is to study the behaviour of NDs suspended in water under ionizing radiations (X-ray and Gamma) and to investigate the production of reactive oxygen species (ROS), in particular hydroxyl radicals (HO). Additional experiments allow to detect also produced solvated electrons (eaq). The detection of HO radicals and solvated electrons was realized in the presence of a fluorescence probe, the 7 OH-coumarin, under various atmospheres (air and N2O/O2). Starting from the same source of NDs, different surface chemistries were compared (oxidized, hydrogenated and surface graphitized). In parallel, colloidal properties and stability of these modified NDs in water with respect to their surface chemistry were investigated at short and long term. An overproduction of HO was observed for H-NDs for both hydrogenation methods and vacuum annealed NDs at 750°C. In addition, the production of solvated electrons was confirmed for H-NDs. These results were discussed taking into account the surface chemistry, the colloidal stability and specific interactions of water molecules with NDs.Parmi tous les nanomatériaux carbonés, les nanodiamants de détonation (NDs) possèdent des propriétés physico-chimiques exceptionnelles faisant d’eux un matériau idéal pour les applications en biologie. Aujourd’hui, la production industrielle permet de synthétiser des NDs ayant une taille de 5 nm comportant un cœur diamant et une enveloppe de surface possédant différentes terminaisons. La chimie de surface des NDs peut être modifiée par recuit ou par plasma donnant des NDs négativement ou positivement chargés en suspension dans l’eau. Notre équipe a récemment démontré des propriétés radiosensibilisantes des NDs hydrogénés par plasma (H-NDs) sur des lignées cellulaires cancéreuses radiorésistantes. Ces résultats prouvent leur aptitude thérapeutique comme agents radiosensibilisants. Cependant, les mécanismes impliqués dans cet effet ne sont pas bien compris. L’objectif principal de ce travail de thèse est d’étudier le comportement des NDs en suspension dans l’eau sous irradiation (rayons X et gamma) et de mesurer la production d’espèces réactives de l’oxygène (ROS) en particulier les radicaux hydroxyles HO. Des expériences complémentaires ont permis de détecter la production d’électrons solvatés (eaq). La détection des radicaux HO et des électrons solvatés (eaq) a été réalisée en utilisant une sonde fluorescence, la 7 OH-coumarine, dans des atmosphères différentes (air and N2O/O2). Différentes chimies de surface ont été comparées (oxydée, hydrogénée, graphitisée en surface) préparées à partir de la même source de NDs. En parallèle, les propriétés colloïdales et la stabilité de ces NDs dans l’eau ont été étudiées à court et à long terme en fonction de leur chimie de surface. Une surproduction de radicaux HO a été mesurée pour les H-NDs hydrogénés par les deux méthodes et pour les NDs recuites sous vide à 750°C. De plus, une surproduction d’électrons solvatés a été mise en évidence pour les H-NDs. Ces résultats sont discutés en fonction de la chimie de surface, la stabilité colloïdale et les interactions spécifiques des molécules d’eau avec les NDs

Zależność własności mechanicznych źdźbeł pszenżyta od ich parametrów morfologicznych

W pracy przedstawiono wieloparametrowe równania opisujące zależność własności mechanicznych źdźbeł pszenżyta od ich pola przekroju poprzecznego, długości międzywęźla oraz wilgotności.The stalks of three triticale varieties were tested at the milk maturity. Bio- metric and ultrasonic measurements helped to determine the mechanical properties of stalks and their morphological parameters. The relationships between them were described by multiparameter equations resulting from the application of multiple regression. High values of r-squared coefficients give evidence for a good adjusting of regression models to empirical data

Electrostatic self-assembly of diamond nanoparticles onto Al- and N-Polar sputtered aluminum nitride surfaces

Electrostatic self-assembly of diamond nanoparticles (DNPs) onto substrate surfaces (so-called nanodiamond seeding) is a notable technique, enabling chemical vapor deposition (CVD) of nanocrystalline diamond thin films on non-diamond substrates. In this study, we examine this technique onto differently polarized (either Al- or N-polar) c-axis oriented sputtered aluminum nitride (AlN) film surfaces. This investigation shows that Al-polar films, as compared to N-polar ones, obtain DNPs with higher density and more homogeneously on their surfaces. The origin of these differences in density and homogeneity is discussed based on the hydrolysis behavior of AlN surfaces in aqueous suspensions