Papers by Christine Roques
Médecine et Maladies Infectieuses, 1997
ABSTRACT
Current Issues in Molecular Biology, 2011
The pathogenesis of periodontitis involves the interplay of microbiota present in the subgingival... more The pathogenesis of periodontitis involves the interplay of microbiota present in the subgingival plaque and the host responses. Inflammation and destruction of periodontal tissues are considered to result from the response of a susceptible host to a microbial biofilm containing gramnegative pathogens. Antimicrobial peptides are important contributors to maintaining the balance between health and disease in this complex environment. These include several salivary antimicrobial peptides such as β-defensins expressed in the epithelium and LL-37 expressed in both epithelium and neutrophils. Among gram-negative bacteria implicated in periodontal diseases, Fusobacterium nucleatum, is one of the most interesting. This review will focus on expression, function, regulation and functional efficacy of antimicrobial peptides against F. nucleatum. We are looking for how the presence of F. nucleatum induces secretion of peptides which have an impact on host cells and modulate immune response.
Journal of Membrane Science, Sep 30, 2011
A series of experiments has been carried out to determine the Log removal value (LRV) of MS2 bact... more A series of experiments has been carried out to determine the Log removal value (LRV) of MS2 bacteriophages suspended in various buffers (osmosed water, tap water, aqueous solutions of NaCl and phosphate buffer solution) during filtration through hollow fiber membranes made of cellulose acetate. Viral concentrations in permeate and retentate were determined using two different methods, namely plaque forming unit (PFU) counting, which reveals only infectious particles and quantitative RT-PCR which detects the total (infectious + inactivated) number of viral genomes regardless of their infectivity.
Journal of Essential Oil Research, Dec 8, 2011
The existing methods for studying the antimicrobial activity of essential oils (e.g. the dilution... more The existing methods for studying the antimicrobial activity of essential oils (e.g. the dilution of the test substances in broth or agar medium) are not adequate to evaluate the effects of the volatile components. Growth inhibition of fungi by various essential oils was determined by direct contact in broth and agar media and compared with the fungistatic action of their
Http Dx Doi Org 10 1080 08927014 2012 695351, Jun 11, 2012
Bacterial behavior during filtration is complex and is influenced by numerous factors. The aim of... more Bacterial behavior during filtration is complex and is influenced by numerous factors. The aim of this paper is to report on experiments designed to make progress in the understanding of bacterial transfer in filters and membranes. Polydimethylsiloxane (PDMS) microsystems were built to allow direct dynamic observation of bacterial transfer across different microchannel geometries mimicking filtration processes. When filtering Escherichia coli suspensions in such devices, the bacteria accumulated in the downstream zone of the filter forming long streamers undulating in the flow. Confocal microscopy and 3D reconstruction of streamers showed how the streamers are connected to the filter and how they form in the stream. Streamer development was found to be influenced by the flow configuration and the presence of connections or tortuosity between channels. Experiments showed that streamer formation was greatest in a filtration system composed of staggered arrays of squares 10 mm apart.
Http Dx Doi Org 10 1080 08927014 2010 520159, Sep 9, 2010
Currently, models for studying Legionella pneumophila biofilm formation rely on multi-species bio... more Currently, models for studying Legionella pneumophila biofilm formation rely on multi-species biofilms with low reproducibility or on growth in rich medium, where planktonic growth is unavoidable. The present study describes a new medium adapted to the growth of L. pneumophila monospecies biofilms in vitro. A microplate model was used to test several media. After incubation for 6 days in a specific biofilm broth not supporting planktonic growth, biofilms consisted of 5.36 ± 0.40 log (cfu cm(-2)) or 5.34 ± 0.33 log (gu cm(-2)). The adhered population remained stable for up to 3 weeks after initial inoculation. In situ confocal microscope observations revealed a typical biofilm structure, comprising cell clusters ranging up to approximately 300 μm in height. This model is adapted to growing monospecies L. pneumophila biofilms that are structurally different from biofilms formed in a rich medium. High reproducibility and the absence of other microbial species make this model useful for studying genes involved in biofilm formation.
Journal Français d Ophtalmologie
Bacterial adhesion to intraocular lenses (IOLs) takes place during their implantation. This is a ... more Bacterial adhesion to intraocular lenses (IOLs) takes place during their implantation. This is a prominent etiological factor of postoperative endophthalmitis. Following adhesion, secretion of an extracellular matrix (called slime for Staphylococcus epidermidis) and formation of multiple layers of microcolonies lead to the colonization of the biomaterial surface. Scanning electron microscopy photographs illustrate the different steps of biofilm formation. The different adhesins expressed by S. epidermidis involved in the adhesion process are described. The biofilm is not only an adhesive medium; it also affects virulence. Last, notions on biofilm physiology are discussed in an attempt to explain the dynamic equilibrium of this system. In 2004, the perfect biomaterial able to prevent postoperative endophthalmitis does not yet exist. Moreover, there is no effective tool, at the present time, to fight against mature biofilms. Therefore, preventing biofilm formation remains capital, which requires perfect knowledge of all stages of formation and the factors involved.
Journal francais d'ophtalmologie
Postoperative endophthalmitis is still one of the most fearsome complications of cataract surgery... more Postoperative endophthalmitis is still one of the most fearsome complications of cataract surgery. The present review's aims are to study the etiology and pathogenesis of endophthalmitis and the criteria for antibiotic prophylaxis. Endophthalmitis prevalence is 0.07%-0.32% in cataract surgery. The clinical presentation needs to be perfectly known, even if none of the signs is pathognomonic. Bacteria predominantly cultured in postoperative endophthalmitis are gram-positive, especially Staphylococcus epidermidis. Most of the bacteria come from the patient. Bacterial adhesion to intraocular lenses (IOLs) takes place during their implantation, a prominent etiological factor. Polypropylene was the first biomaterial that proved this relation of cause and effect between bacterial adhesion and endophthalmitis. The benefit of antibiotic prophylaxis during cataract surgery has yet not been proven, since the low prevalence of endophthalmitis makes controlled studies with a large cohort difficult. The criteria and the four possible administration approaches (topical, subconjunctival, irrigation liquid, systemic) are analyzed.
Journal of ethnopharmacology
Canadian Journal of Microbiology
European Journal of Medicinal Chemistry
Developments in biological standardization
Treatment of healthy volunteers by Ribomunyl, whether or not in association with in vitro antibio... more Treatment of healthy volunteers by Ribomunyl, whether or not in association with in vitro antibiotics (amoxicillin or josamycin), has been earlier demonstrated to be an efficient stimulant of PMN functions (adhesion and migration). This second double-blind study versus placebo was performed on 17 patients with acute respiratory infections (placebo group: eight subjects; Ribomunyl group: nine subjects). Ribomunyl treatment (four days) associated with antibiotherapy (amoxicillin) induced a significant increase of PMN adhesion (p = 0.014) with no significant effect of the placebo (p = 0.30) and no significant difference between the initial level of PMN adhesion of the two groups (placebo-Ribomunyl).
Journal de parodontologie
Bactericidal activities of five mouthrinses containing cetylpyridinium chloride, hexetidine or ch... more Bactericidal activities of five mouthrinses containing cetylpyridinium chloride, hexetidine or chlorhexidine have been tested in vitro, against the main microorganisms involved in buccal affections. Mouthrinses containing hexetidine or chlorhexidine are effective, but chlorhexidine activity appears more extensive and homogeneous.
Pathologie Biologie
The study of bacterial colonization by Streptococcus mutans on dental surfaces of rat have been u... more The study of bacterial colonization by Streptococcus mutans on dental surfaces of rat have been undertaken in vivo in gnotobiotic rat, and in vitro in an artificial mouth model, in order to validate the suitability of such a model. The study of colonization by Streptococcus mutans with time showed a similar kinetic of the monobacterial plaque formation in the two experimentations. Three phases were observed. A logarithmic phase in the earliest hours after inoculation of bacterium, followed by an exponential phase, and finally a stabilization phase of the monobacterial plaque formed in this way from the third day. Nevertheless, if the kinetic is the same, it is observed a more important colonization of dental surfaces in rat. This phenomenon was explained by the simplification of biological conditions encountered in the in vitro model. In particular, it is noticed the important saliva action. It is concluded that the in vitro model developed simulate suitably the conditions of the oral environment encountered in vivo.
Pathologie Biologie
The interaction type of chlorhexidine digluconate/chlorocresol association (foaming solution DC 1... more The interaction type of chlorhexidine digluconate/chlorocresol association (foaming solution DC 102/1, Laboratoires Pierre Fabre Médicament) have been studied according to the chess-board method, on microplate, by determining MBC (Minimal Bactericidal Concentrations) (or MFC (Minimal Fungicidal Concentrations)) adjusted to T 72-150 AFNOR norm (dilution-neutralization, contact 5 mn) and computation of FBC (or FFC) Index. Trials were carried out against 18 hospital strains (Staphylococcus epidermidis, Staphylococcus aureus, Propionibacterium acnes, Candida albicans) and against 4 strains of the AF-NOR norm. MBC of chlorhexidine, against Staphylococci were included between 6.25 and 25 micrograms/ml, and between 25 and 200 micrograms/ml against the others strains. MBC of chlorocresol were included between 800 and 3,200 micrograms/ml. Against the 22 tested strains, 18 synergistic interactions (FBC Index < or = 0.75) were observed, with 4 to 8 reducing factor for chlorhexidine, and > or = 2 for chlorocresol. No antagonism was noted (maximal FBC Index = 1).
Journal of Essential Oil Research
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Papers by Christine Roques