Molecular Insights into the Uropathogenesis of Enterococcus faecalis and Escherichia coli in the Context of Urinary Catheterization

Nosocomial urinary tract infections: UTIs) are a very common result of catheterization with 3 to 7% risk of developing catheter-associated UTIs: CAUTIs) each day catheterized. As multi-drug resistance increases in uropathogens, it is imperative to better understand the effects of catheterization on the urinary tract and pathogenesis. Further, microbial colonization and biofilm production on the surface of urinary catheters are a common component of CAUTIs. Thus, this dissertation focuses on understanding the contribution of known biofilm determinants to urovirulence of Enterococcus faecalis: a common nosocomial uropathogen) and uropathogenic Escherichia coli: UPEC): the most common causative agent of UTI), and the effects of catheterization on bladder physiology using in vitro and optimized in vivo models. In vitro studies reported here demonstrated that E. faecalis produces DNA-dependent biofilms, which require both SrtA and Atn for efficient attachment as well as extracellular DNA from autolytic processes during the accumulative phase for maturation and architectural stability of the biofilm under both static and hydronamic conditions. Further, in vivo studies optimizing and using a rodent model of foreign body-associated UTI to mimic conditions of indwelling urinary catheters in humans underscored the importance of biofilm formation, although in vivo required only a subset of the identified in vitro biofilm-promoting factors such as sortases, for the establishment of persistent enterococcal UTIs despite the acute inflammatory response ensuing from urinary implantation. This response was characterized in these studies and shown to involve bladder wall edema, partial disruption of the epithelial layer, vascular permeability, production of pro-inflammatory cytokines, and recruitment of myeloid cells, particularly neutrophils. During infection of implanted murine bladders, it was shown that type 1 pili mediate UPEC adherence and invasion, similar to what was observed in non-catheterized bladders. Studies in this murine model further demonstrated that microbial reservoirs established during previous UPEC infection could serve as a nidus for urinary catheter colonization upon subsequent implantation. Specific targeting of type 1 pili with small molecule inhibitors of the pilus tip adhesin, FimH, in combination with trimethoprim/sulfamethoxazole prevented UPEC CAUTI. This finding establishes a proof-of-principle for the development of novel therapies to prevent and eventually treat UPEC CAUTI in the face of the rise of antibiotic resistant uropathogens. Overall, the optimization and use of the murine model of foreign body-associated UTI represents a significant advance in the understanding of the pathophysiology of E. faecalis and UPEC uropathogenesis in CAUTIs and is a valuable tool for the identification of virulence factors, including enterococcal sortases and UPEC type 1 pili, involved in these infections. Further research is required to uncover other biofilm and virulence determinants specifically required for UTIs as well as host factors that can serve as potential antimicrobial targets and biomarkers for the prevention, diagnosis, and treatment of enterococcal and UPEC CAUTIs

Synthesis of Metal Oxide Surfaces and Interfaces with Crystallographic Control Using Solid-Liquid-Vapor Etching and Vapor-Liquid-Solid Growth

The present invention provides integrated nanostructures comprising a single-crystalline matrix of a material A containing aligned, single-crystalline nanowires of a material B, with well-defined crystallographic interfaces are disclosed. The nanocomposite is fabricated by utilizing metal nanodroplets in two subsequent catalytic steps: solid-liquid-vapor etching, followed by vapor-liquid-solid growth. The first etching step produces pores, or “negative nanowires” within a single-crystalline matrix, which share a unique crystallographic direction, and are therefore aligned with respect to one another. Further, since they are contained within a single, crystalline, matrix, their size and spacing can be controlled by their interacting strain fields, and the array is easily manipulated as a single entity—addressing a great challenge to the integration of freestanding nanowires into functional materials. In the second, growth, step, the same metal nanoparticles are used to fill the pores with single-crystalline nanowires, which similarly to the negative nanowires have unique growth directions, and well-defined sizes and spacings. The two parts of this composite behave synergistically, since this nanowire-filled matrix contains a dense array of well-defined crystallographic interfaces, in which both the matrix and nanowire materials convey functionality to the material. The material of either one of these components may be chosen from a vast library of any material able to form a eutectic alloy with the metal in question, including but not limited to every material thus far grown in nanowire form using the ubiquitous vapor-liquid-solid approach. This has profound implications for the fabrication of any material intended to contain a functional interface, since high interfacial areas and high quality interfacial structure should be expected. Technologies to which this simple approach could be applied include but are not limited to p-n junctions of solar cells, battery electrode arrays, multiferroic materials, and plasmonic materials

Designing Sustainable Technologies, Products and Policies

This open access book provides insight into the implementation of Life Cycle approaches along the entire business value chain, supporting environmental, social and economic sustainability related to the development of industrial technologies, products, services and policies; and the development and management of smart agricultural systems, smart mobility systems, urban infrastructures and energy for the built environment. The book is based on papers presented at the 8th International Life Cycle Management Conference that took place from September 3-6, 2017 in Luxembourg, and which was organized by the Luxembourg Institute of Science and Technology (LIST) and the University of Luxembourg in the framework of the LCM Conference Series

Estimates of fracture density and uncertainties from well data

International audienceThis paper aims at building a method to estimate the probability law governing the 3D fracture density of a fractured rock conditioned to the number of traces observed on a borehole image when the spatial distribution of fracture centers is assumed to follow a Poisson process. A closed-form expression of this law, allowing to calculate its mean value as well as a confidence interval, is derived in both cases of a lineic well (scanline) and a cylindrical well. The latter is better adapted to the situation of fracture size of the same order of magnitude as the well radius, which enables the presence of partial traces. In particular, the method takes into account the bias in the density estimate due to the fact that a fracture may cut the well along two distinct traces according to the considered fracture size. Monte Carlo simulations finally show a good agreement with the theoretical results of mean density and confidence interval

Synthesis of VO_2 Nanowire and Observation of the Metal-Insulator Transition

We have fabricated crystalline nanowires of VO_2 using a new synthetic method. A nanowire synthesized at 650^oC shows the semiconducting behavior and a nanowire at 670^oC exhibits the first-order metal-insulator transition which is not the one-dimensional property. The temperature coefficient of resistance in the semiconducting nanowire is 7.06 %/K at 300 K, which is higher than that of commercial bolometer.Comment: 3 pages, 4 figures, This was presented in NANOMAT 2006 "International workshop on nanostructed materials" on June 21-23th of 2006 in Antalya/TURKE

An Optimization method for the Configuration of Inter Array Cables for Floating Offshore Wind Farm.

International audienceIFP Energies nouvelles (IFPEN) is involved for many years in various projects for the development of floating offshore wind turbines. The commercial deployment of such technologies is planned for 2020. The present paper proposes a methodology for the numerical optimization of the inter array cable configuration. To illustrate the potential of such an optimization, results are presented for a case study with a specific floating foundation concept [1]. The optimization study performed aims to define the least expensive configuration satisfying mechanical constraints under extreme environmental conditions. The parameters to be optimized are the total length, the armoring, the stiffener geometry and the buoyancy modules. The insulated electrical conductors and overall sheath are not concerned by this optimization. The simulations are carried out using DeepLines TM , a Finite Element software dedicated to simulate offshore floating structures in their marine environment. The optimization problem is solved using an IFPEN in-house tool, which integrates a state of the art derivative-free trust region optimization method extended to nonlinear constrained problems. The latter functionality is essential for this type of optimization problem where nonlinear constraints are introduced such as maximum tension, no compression, maximum curvature and elongation, and the aero-hydrodynamic simulation solver does not provide any gradient information. The optimization tool is able to find various local feasible extrema thanks to a multi-start approach, which leads to several solutions of the cable configuration. The sensitivity to the choice of the initial point is demonstrated, illustrating the complexity of the feasible domain and the resulting difficulty in finding the global optimum configuration