Convexité et equations de Cauchy-Riemann avec estimations Lp

We obtain a solution of the equation [delta]u = f as an integral supported only on the bounded convex domain D of Cn, without finite type assumption. We show that u is in Lp (0,q-1)(D) if f [member of] Lp (0,q)(D) and [formula] [member of] Lp (0,q+1)(D) for some [epsilon] depending on p and q, 0 < [epsilon] [less than or equal] 1

Conterpoint to the « Eloge de la bicyclette »

The arrival of private enterprises on urban the bike rental scene has seen a return to cycling. Since 2005, many large cities have equipped themselves with tools of ecological resonance in order to develop new energy policies. Despite this, there are relatively few citizens who adhere to this ideology in practice. Some observations have revealed a number of complex uses linked to professional activities and diverse journeys. As a counter-point to the publication by Marc Augé, this article is a reflection centred on the day-to-day, showing through a reflective approach, a social phenomenon in the making.L'arrivée d'entreprises privées de location de vélos dans la ville a permis un retour de la pratique cycliste. Depuis 2005, les grandes villes se dotent d'outils aux consonances écologiques pour développer une politique énergétique nouvelle. Malgré cela, les citoyens restent peu nombreux dans l'ensemble à adhérer à cette idéologie par la pratique. Quelques observations permettent de découvrir un ensemble complexe d'usages, liés au monde du travail et aux déplacements. Tel un contrepoint à l'ouvrage de Marc Augé, cet article ouvre sur une réflexion centrée sur un quotidien, montrant à travers une démarche réflexive un phénomène social en devenir

Contrepoint à l' " Eloge de la bicyclette "

The arrival of private enterprises on urban the bike rental scene has seen a return to cycling. Since 2005, many large cities have equipped themselves with tools of ecological resonance in order to develop new energy policies. Despite this, there are relatively few citizens who adhere to this ideology in practice. Some observations have revealed a number of complex uses linked to professional activities and diverse journeys. As a counter-point to the publication by Marc Augé, this article is a reflection centred on the day-to-day, showing through a reflective approach, a social phenomenon in the making.L'arrivée d'entreprises privées de location de vélos dans la ville a permis un retour de la pratique cycliste. Depuis 2005, les grandes villes se dotent d'outils aux consonances écologiques pour développer une politique énergétique nouvelle. Malgré cela, les citoyens restent peu nombreux dans l'ensemble à adhérer à cette idéologie par la pratique. Quelques observations permettent de découvrir un ensemble complexe d'usages, liés au monde du travail et aux déplacements. Tel un contrepoint à l'ouvrage de Marc Augé, cet article ouvre sur une réflexion centrée sur un quotidien, montrant à travers une démarche réflexive un phénomène social en devenir

OMP proteomic analysis of benzalkonium chloride and ciprofloxacin adapted biofilm cells

Adaptive resistance to antimicrobials has been widely reported in planktonic studied trough phenotypic characterization and proteomic analysis. Concerning biofilm adaptation, the response of biofilm-entrapped cells to chemical stress conditions is not yet well studied. There is evidence that proteins involved in oxidative stress response, cell envelope synthesis, as well as in synthesis of EPS become up- or down-regulated in biofilms, indicating that these altered phenotypes might contribute to antimicrobial tolerance. This work aimed to examine whether exposure of Pseudomonas aeruginosa biofilms to benzalkonium chloride (BC) and ciprofloxacin (CIP) could induce an adaptive response in bacteria. This was attained by inspection of proteome alterations of the outer membrane (OMP) in biofilm cells. Biofilms were formed in 6-well plates for 24h being after submitted to the presence of 0.9 mM BC and 6.0 ug/ml CIP, during 13 days. The obtained biofilm-cells were separated and the OMP extracted. Protein patterns were analysed by 2-DE and gels by the SameSpot software. Biofilm-proteome showed that P. aeruginosa adaptation to BC promoted the down-regulation of 36 OMP and the up-regulation of only one. OMP 2DE of P. aeruginosa adapted to CIP revealed the down-regulation of 29 OMP. Six OMPs were changed in common by both antimicrobials, revealing a possible similar stress response. Proteins identification is in progress. This study highlighted that there might be an OMP regulation when bacteria within biofilms are submitted to chemical adaptation. This particular response to the environment can be one of the causes of the well-known biofilm resistance phenotype

Membranome analysis of benzalkonium chloride adapted planktonic and biofilm cells

Este resumo faz parte de: Book of abstracts of the Meeting of the Institute for Biotechnology and Bioengineering, 2, Braga, Portugal, 2010. A versão completa do livro de atas está disponível em: http://hdl.handle.net/1822/1096

Proteomic characterization of Benzalkonium Chloride- and Ciprofloxacin-adapted Pseudomonas aeruginosa biofilms

Bacteria are able to adapt to several environmental stresses such as the presence of antimicrobial molecules and, as consequence, bacterial resistance may increase with increasing exposure to antimicrobials. The most impressive mechanism of the bacterial mode of life is their grow as part of a sessile community referred to as biofilm [1]. Biofilm formation is an important aspect of many bacterial diseases, especially those related with medical devices [2]. When biofilms are identified as the cause of infection, treatment becomes very difficult since bacteria within biofilms demonstrate peculiar features, that confer them increased resistance to biocides. The adaptive response to antimicrobial stresses of sessile bacteria is more effective than the corresponding planktonic populations. Adaptive resistance to antimicrobials has been widely reported in planktonic state and characterized in terms of phenotypic traits and proteomic analysis [3,4]. Concerning biofilm adaptation, the response of the biofilm-entrapped cells to chemical stress conditions is not yet well studied. This work aimed to examine whether exposure of Pseudomonas aeruginosa biofilms to benzalkonium chloride (BC) and ciprofloxacin (CIP) during a laboratory adaptation process could induce any proteomic alterations in the outer membrane (OM) of the biofilm cells. Biofilms were formed in 6-well plates for 24 h being after submitted to the presence of 324 mg/L of BC and 6.0 mg/L of CIP, during 13 days. The obtained biofilm-cells were separated from the biofilm matrix and the OM proteins extracted. Protein patterns were analyzed by 2-DE and gels by Progenesis SameSpot software. Protein spots from the bacterial populations were considered to display significant quantitative differences if they fulfilled the following criteria: p values ≤ 0.05 (t-test); detection threshold, average volume ≥ 20 (n = 3); differential tolerance, fold change ≥ 2. Excised spots from three different gels of each adapted bacteria were identified by LC-MS/MS. Biofilm proteome analysis showed that P. aeruginosa adaptation to BC and CIP changed the expression of six proteins. The biofilm exposure to both antimicrobials generated common down-regulation of three proteins: GroEL, major capsid protein and putative tail sheath protein, revealing a possible similar stress response. The type 4 fimbrial biogenesis outer membrane protein PilQ precursor was over-expressed only in biofilms submitted to BC, while the probable bacteriophage protein and the hypothetical protein PA0537 were overexpressed in CIP exposed biofilms. When bacteria are within biofilms and exposed to chemical stress, the regulation of OM proteins expression can contribute to increase the biofilm resistance. The proteins involved in adhesion, oxidative stress response, as well as in synthesis of lipopolysaccharide, were upor down-regulated in adapted P. aruginosa biofilms. These acquired proteomic profiles may be associated with antimicrobial tolerance

Proteomic approach to Pseudomonas aeruginosa adaptive resistance to benzalkonium chloride

This study aimed to assess the membrane modifications in Pseudomonas aeruginosa after continuous exposure to increasing doses of benzalkonium chloride (BC). Two different concentrations were used, 0.9 and 12.0 mM. Proteomic investigations revealed that the range of the outermembrane proteome alterations following continuous exposure is very low, i.e. about 10% and BC concentration dependent. Adapted cells revealed different expressions of key proteins frequently reported as involved in acquired resistance mechanisms. Porins (OprF and OprG) and lipoproteins (OprL and OprI) were underexpressed when the higher adaptation concentration (12 mM) was used. Some of thesemembrane alterations have been described as involved in the acquired resistance to antibiotics, suggesting possible commonmechanisms between these two types of resistance.The authors would like to acknowledge the financial support from IBB-CEB and Fundacao para a Ciencia e Tecnologia (FCT) and European Community fund FEDER, through Program COMPETE, in the ambit of the Project PTDC/SAUESA/64609/2006/FCOMP-01-0124-FEDER-00702 and Idalina Machado PhD Grant (SFRH/BD/31065/2006)

Unsaturated Fatty Acids Affect Quorum Sensing Communication System and Inhibit Motility and Biofilm Formation of Acinetobacter baumannii

The increasing threat of Acinetobacter baumannii as a nosocomial pathogen is mainly due to the occurrence of multidrug-resistant strains that are associated with the real problem of its eradication from hospital wards. The particular ability of this pathogen to form biofilms contributes to its persistence, increases antibiotic resistance, and promotes persistent/device-related infections. We previously demonstrated that virstatin, which is a small organic compound known to decrease virulence of Vibrio cholera via an inhibition of T4-pili expression, displayed very promising activity to prevent A. baumannii biofilm development. Here, we examined the antibiofilm activity of mono-unsaturated chain fatty acids, palmitoleic (PoA), and myristoleic (MoA) acids, presenting similar action on V. cholerae virulence. We demonstrated that PoA and MoA (at 0.02 mg/mL) were able to decrease A. baumannii ATCC 17978 biofilm formation up to 38% and 24%, respectively, presented a biofilm dispersing effect and drastically reduced motility. We highlighted that these fatty acids decreased the expression of the regulator abaR from the LuxIR-type quorum sensing (QS) communication system AbaIR and consequently reduced the N-acyl-homoserine lactone production (AHL). This effect can be countered by addition of exogenous AHLs. Besides, fatty acids may have additional non-targeted effects, independent from QS. Atomic force microscopy experiments probed indeed that PoA and MoA could also act on the initial adhesion process in modifying the material interface properties. Evaluation of fatty acids effect on 22 clinical isolates showed a strain-dependent antibiofilm activity, which was not correlated to hydrophobicity or pellicle formation ability of the tested strains, and suggested a real diversity in cell-to-cell communication systems involved in A. baumannii biofilm formation.Peer reviewe