Propriétés antibactériennes d’extraits de propolis contre des souches de Staphylococcus aureus sensibles ou résistantes à la méthicilline

La résistance aux antibiotiques est devenue l\u27un des problèmes majeurs de santé publique du XXIème siècle. Il existe donc un réel intérêt thérapeutique dans la recherche de composés ou d\u27extraits naturels capables de limiter cette résistance. La propolis est un mélange complexe composé de substances résineuses collectées par les abeilles sur différentes parties des plantes et arbres, de cires et de sécrétions salivaires de l\u27abeille. Elle sert principalement à colmater les interstices des parois de la ruche et comme véritable arme chimique contre les microorganismes. La propolis est utilisée depuis longtemps en médecine traditionnelle puisqu\u27elle possède des propriétés pharmacologiques intéressantes notamment antioxydante, anti-inflammatoire mais aussi antimicrobienne. Un échantillon de propolis, composé de 24 lots collectés en France (majoritairement dans le sud-ouest) en 2010 et 2011, a été extrait par différents solvants : EtOH 70%, MeOH, DCM et DCM/MeOH/eau 31/19/4 (mixte). La composition chimique des extraits a préalablement été déterminée au moyen d’analyses HPLC/DAD/MS et RMN 1H et 13C. L\u27activité antibactérienne a été évaluée sur des bactéries responsables d\u27infections nosocomiales, et plus spécifiquement sur 13 souches de Staphylococcus aureus [ATCC25923, six isolats cliniques de souches résistantes à la méthiciline (SARM) et six isolats cliniques de souches sensibles à la méthiciline (SASM)] par détermination de la concentration minimum d\u27inhibition (CMI) en milieu gélosé [1]. Les résultats ont montré que, parmi les quatre extraits, le DCM et le "mixte" présentaient une bonne activité antibactérienne contre S. aureus (SA) avec des CMI respectives de 60±10 et 67±15 µg/mL mais également sur quasiment toutes les souches SARM et SASM testées (CMI entre 30 et 97 µg/mL). Ces bonnes activités des extraits DCM et mixte peuvent être reliées à des teneurs élevées en polyphénols totaux et en flavonoïdes [1]. Diverses études ont en effet montré que ce type de mélange complexe, riche en polyphénols, était plus actif que les composés isolés les constituant. Les polyphénols agiraient ainsi de façon synergique, potentialisant l\u27activité antibactérienne de ces extraits [2]. D\u27autres études, menées in vitro, ont par ailleurs mis en évidence un réel synergisme entre propolis et antibiotiques [3], [4]. Ainsi, ces extraits de propolis présentent-ils un réel potentiel dans une lutte alternative contre des infections à staphylocoques.   Références [1]          S. Boisard et al., "Antifungal and Antibacterial Metabolites from a French Poplar Type Propolis", Evid. Based Complement. Alternat. Med., vol. 2015, p. e319240, 2015. [2]          A. Kujumgiev, I. Tsvetkova, Y. Serkedjieva, V. Bankova, R. Christov, et S. Popov, "Antibacterial, antifungal and antiviral activity of propolis of different geographic origin", J. Ethnopharmacol., vol. 64, no 3, p. 235‑240, 1999. [3]          S. Stepanović, N. Antić, I. Dakić, et M. Švabić-Vlahović, "In vitro antimicrobial activity of propolis and synergism between propolis and antimicrobial drugs", Microbiol. Res., vol. 158, no 4, p. 353‑357, 2003. [4]          A. Fernandes Júnior, E. C. Balestrin, J. E. C. Betoni, R. de O. Orsi, M. de L. R. de S. da Cunha, et A. C. Montelli, "Propolis: anti-Staphylococcus aureus activity and synergism with antimicrobial drugs", Mem. Inst. Oswaldo Cruz, vol. 100, no 5, p. 563‑566, 2005

Polyphenolic content and pharmacological potential of french BFA propolis extracts

Propolis, or bee glue, is a natural resinous hive product collected by honeybees from buds and exudates of various trees and plants. Mixed with beewax and salivary enzymes, it is employed to fill cracks and embalm dead invaders in the hive. Propolis has been used in folk medecine since ancien times due to its pharmacological potential associated with antioxidant, antifungal, antibacterial as well as antitumoral properties. A batch of various French propolis extracts, supplied by “Ballot-Flurin Apiculteurs” (BFA), a company located in the South-West of France and specialized in apitherapy products, was fractionated and analysed by HPLC/MS. Its qualitative chemical composition highlights the presence of polyphenols such as hydroxycinnamic acid derivatives and flavonoids. Total polyphenol content and antioxidant activities were evaluated on six BFA propolis extracts, using respectively Folin-Ciocalteu, DPPH and ORAC assays. Preliminary antifungal (Candida albicans) and antibacterial (Staphylococcus aureus) evaluations will also be given

Quantum walks: a comprehensive review

Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important result: the computational universality of both continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing Journa

Cumulative burden of depression and all-cause mortality in women living with human immunodeficiency virus

Background Research linking depression to mortality among people living with human immunodeficiency virus (PLWH) has largely focused on binary "always vs never" characterizations of depression. However, depression is chronic and is likely to have cumulative effects on mortality over time. Quantifying depression as a cumulative exposure may provide a better indication of the clinical benefit of enhanced depression treatment protocols delivered in HIV care settings. Methods Women living with HIV (WLWH), naive to antiretroviral therapy, from the Women's Interagency HIV Study were followed from their first visit in or after 1998 for up to 10 semiannual visits (5 years). Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. An area-under-the-curve approach was used to translate CES-D scores into a time-updated measure of cumulative days with depression (CDWD). We estimated the effect of CDWD on all-cause mortality using marginal structural Cox proportional hazards models. Results Overall, 818 women contributed 3292 woman-years over a median of 4.8 years of follow-up, during which the median (interquartile range) CDWD was 366 (97-853). Ninety-four women died during follow-up (2.9 deaths/100 woman-years). A dose-response relationship was observed between CDWD and mortality. Each additional 365 days spent with depression increased mortality risk by 72% (hazard ratio, 1.72; 95% confidence interval, 1.34-2.20). Conclusions In this sample of WLWH, increased CDWD elevated mortality rates in a dose-response fashion. More frequent monitoring and enhanced depression treatment protocols designed to reduce CDWD may interrupt the accumulation of mortality risk among WLWH

Identification of New SRF Binding Sites in Genes Modulated by SRF Over-Expression in Mouse Hearts

Background To identify in vivo new cardiac binding sites of serum response factor (SRF) in genes and to study the response of these genes to mild over-expression of SRF, we employed a cardiac-specific, transgenic mouse model, with mild over-expression of SRF (Mild-O SRF Tg). Methodology Microarray experiments were performed on hearts of Mild-O-SRF Tg at 6 months of age. We identified 207 genes that are important for cardiac function that were differentially expressed in vivo. Among them the promoter region of 192 genes had SRF binding motifs, the classic CArG or CArG-like (CArG-L) elements. Fifty-one of the 56 genes with classic SRF binding sites had not been previously reported. These SRF-modulated genes were grouped into 12 categories based on their function. It was observed that genes associated with cardiac energy metabolism shifted toward that of carbohydrate metabolism and away from that of fatty acid metabolism. The expression of genes that are involved in transcription and ion regulation were decreased, but expression of cytoskeletal genes was significantly increased. Using public databases of mouse models of hemodynamic stress (GEO database), we also found that similar altered expression of the SRF-modulated genes occurred in these hearts with cardiac ischemia or aortic constriction as well. Conclusion and significance SRF-modulated genes are actively regulated under various physiological and pathological conditions. We have discovered that a large number of cardiac genes have classic SRF binding sites and were significantly modulated in the Mild-O-SRF Tg mouse hearts. Hence, the mild elevation of SRF protein in the heart that is observed during typical adult aging may have a major impact on many SRF-modulated genes, thereby affecting Cardiac structure and performance. The results from our study could help to enhance our understanding of SRF regulation of cellular processes in the aged heart

Error analysis of large-eddy simulation of the turbulent non-premixed sydney bluff-body flame

A computational error analysis is applied to the large-eddy simulation of the turbulent non-premixed Sydney bluff-body flame, where the error is defined with respect to experimental data. The errorlandscape approach is extended to heterogeneous compressible turbulence, which is coupled to combustion as described by a flamelet model. The Smagorinsky model formulation is used to model the unknown turbulent stresses. We introduce several measures to quantify the total simulation error and observe a striking ‘valley-structure’ in the error that arises as function of the spatial resolution and the Smagorinsky length parameter. The optimal refinement strategy that can be extracted from this error-landscape is reminiscent of that for non-reacting turbulent flow

A conservative Eulerian-Lagrangian decomposition principle for the solution of multi-scale flow problems at high Schmidt or Prandtl numbers

International audienceThis is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain

LES of lifted flames in a gas turbine model combustor using top-hat filtered PFGM chemistry

Progress variable approaches permit the efficient large eddy simulation (LES) of complex industrial combustion systems, where assumed shape filtered density functions (ß-FDFs) are widely used to account for subgrid scale effects. In this study a new modelling approach for the LES of partially premixed combustion is introduced, which is based on top-hat filtered premixed flamelet-generated manifolds (TH-PFGM) which are consistent with the LES methodology. Due to the top-hat filtering the resulting lookup tables require fewer dimensions than conventional ß-integrated tables, permitting a low-storage representation. In the present paper TH-PFGM is applied to a lifted swirl flame in a model gas turbine combustor. The paper presents the underlying TH-PFGM modelling theory, its extension to any number of dimensions, and simulation results from the LES of the model combustor. Results show that TH-PFGM accurately captures the flame lift off dynamics governed by a low frequency penetration of the flame into the fuel supply, which leads to fluid expansion and in turn flame lift off. The statistical data for flow and species concentration fields from LES are in good accordance with the experimental evidence, as well as results from a comparable LES study

Persistance des Enterobacteriacae resistantes aux fluoroquinolones et à la ciprofloxacin dans le sol après épandage de fumier de poules

International audienceThis study aimed to evaluate the persistence (i) of two fluoroquinolones, enrofloxacin (ENR) and ciprofloxacin (CIP), and (ii) of CIP-resistant Enterobacteriaceae in soil after poultry manure application. The amounts of ENR and CIP in soil did not significantly change over the 48 day- experimental period. CIP (≤ 30 µg kg-1) was detected in weaker concentrations than ENR (20 to 250 µg kg-1 of soil). The concentration of Enterobacteriaceae (102-103 CFU g-1) did not significantly decrease until Day 36. A total of 145 isolates were identified as belonging to E. coli and to 6 genera. The ciprofloxacin MIC of E. coli reached 32 mg L-1 whereas the other strains of Enterobacteriaceae had a MIC ≤ 0.25 mg L-1. The 71 strains of E. coli were classified in 12 ERIC-PCR genotypes. One genotype, corresponding to a resistant strain, was detected until Day 89. This study showed that enrofloxacin and CIP-resistant E. coli persisted at least 48 and 89 days, respectively, in soil. However, their presence did not increase the MIC of Enterobacteriaceae originating from soil