Philippe Gibert

High-performance liquid chromatographic assay for minocycline in human plasma and parotid saliva.

A sensitive and specific high-performance liquid chromatographic (HPLC) method with UV detection was developed for the determination of minocycline in human plasma and parotid saliva samples. Samples were extracted using an Oasis HLB cartridge and were injected into a C8 Nucleosil column. The HPLC eluent contained acetonitrile-methanol-distilled water-0.1% trifluoroacetic acid (25:2:72.9:0.1, v/v). Demeclocycline was used as internal standard. The assay showed linearity in the tested range of 0.1-25 microg/ml. The limit of quantitation was 100 ng/ml. Recovery from plasma or parotid saliva averaged 95%. Precision expressed as %CV was in the range 0.2-17% (limit of quantitation). Accuracy ranged from 93 to 111%. In the two matrices studied at 20 and 4 degrees C, rapid degradation of the drug occurred. Frozen at -30 degrees C, this drug was stable for at least 2 months, the percent recovery averaged 90%. The methods ability to quantify minocycline with precision, accuracy and sensitivity makes it useful in pharmacokinetic studies.

Pseudomonas aeruginosa and Achromobacter sp. Clonal Selection Leads to Successive Waves of Contamination of Water in Dental Care Units

ABSTRACT Dental care unit waterlines (DCUWs) consist of complex networks of thin tubes that facilitate the formation of microbial biofilms. Due to the predilection toward a wet environment, strong adhesion, biofilm formation, and resistance to biocides, Pseudomonas aeruginosa, a major human opportunistic pathogen, is adapted to DCUW colonization. Other nonfermentative Gram-negative bacilli, such as members of the genus Achromobacter, are emerging pathogens found in water networks. We reported the 6.5-year dynamics of bacterial contamination of waterlines in a dental health care center with 61 dental care units (DCUs) connected to the same water supply system. The conditions allowed the selection and the emergence of clones of Achromobacter sp. and P. aeruginosa characterized by multilocus sequence typing, multiplex repetitive elements-based PCR, and restriction fragment length polymorphism in pulsed-field gel electrophoresis, biofilm formation, and antimicrobial susceptibility. One clone of P. aeruginosa and 2 clones of Achromobacter sp. colonized successively all of the DCUWs: the last colonization by P. aeruginosa ST309 led to the closing of the dental care center. Successive dominance of species and clones was linked to biocide treatments. Achromobacter strains were weak biofilm producers compared to P. aeruginosa ST309, but the coculture of P. aeruginosa and Achromobacter enhanced P. aeruginosa ST309 biofilm formation. Intraclonal genomic microevolution was observed in the isolates of P. aeruginosa ST309 collected chronologically and in Achromobacter sp. clone A. The contamination control was achieved by a complete reorganization of the dental health care center by removing the connecting tubes between DCUs.

Variable Selection Method in Prediction Models: Application in Periodontology

The aim of this study, applied in the field of periodontal diseases, was first to analyze the fatty acid levels in two groups of patients and then to propose a method for selecting the most relevant predictors. Two groups of patients, 29 with moderate or severe periodontitis and 27 who served as controls, were clinically examined, and their fatty acids in serum were measured by gas chromatography. The levels of these 12 fatty acids were the variables of the analysis. Logistic regression, together with the area under the receiver operating characteristic (ROC) curves, allowed determining a composite score which led to a subset of the most relevant covariables. The fatty acid levels differed significantly between the 2 groups in multivariate analysis () and the best logistic model was obtained with only 3 predictive variables: arachidonic acid, linoleic acid, and DHA. Fatty acid levels in serum of patients were significantly different according to the presence of moderate or severe periodontitis. By taking into account the comparison of ROC curves, our approach could optimize the choice of variables in multivariate analyses and could better fit it with diagnosis and prognosis of oral diseases in dental research.

Data from a targeted proteomics approach to discover biomarkers in saliva for the clinical diagnosis of periodontitis

This study focused on the search for new biomarkers based on liquid chromatography-multiple reaction monitoring (LC-MRM) proteomics profiling of whole saliva from patients with periodontitis compared to healthy subjects. The LC-MRM profiling approach is a new and innovative method that has already been validated for the absolute and multiplexed quantification of biomarkers in several diseases. The dataset for this study was produced using LC-MRM to monitor protein levels in a multiplex assay, it provides clinical information on salivary biomarkers of periodontitis. The data presented here is an extension of our recently published research article (Mertens et al., 2017) [1].