Multi-center evaluation of the hepatitis B surface antigen (HBsAg) assay and HbsAg confirmatory assay for the family of Access immunoassay systems

BACKGROUND: Accurate detection of Hepatitis B Surface Antigen (HBsAg) is an important aid in the diagnosis of patients infected with the hepatitis B virus (HBV). A multi-center study was conducted to characterize the performance of the HBsAg assay on the family of Access immunoassay systems from Beckman Coulter. METHODS: The Access HBsAg assay was characterized in a multi-center study and compared to the Abbott AxSYM* and PRISM* HBsAg assays. The bioMérieux VIDAS* assay was used to resolve discrepant results. Reproducibility studies (intra-assay, inter-assay and inter-lot) were performed with pooled serum samples (negative sample, close to cut off, low, medium and high positive samples). Analytical sensitivity, subtype and genotype detection were studied with various commercial panels (SFTS panel, WHO 80/549, WHO 00/588, Teragenix HBV Genotype panel). A panel of recombinant HBsAg mutant proteins was tested to investigate reactivity towards genetic mutations. Clinical sensitivity was verified with seroconversion panels and samples from subjects with known HBV infection. Analytical specificity was studied with samples from patients with potential cross-reactive infections. Clinical specificity was validated among blood donors and a hospitalized population. RESULTS: The imprecision was < 10%. Analytical sensitivity was < or = 0.1 ng/mL (SFTS panel), 0.020 PEI Units/mL (ad panel), 0.024 PEI Units/mL (ay panel), 0.092 IU/mL with WHO 80/549 and 0.056 IU/mL with WHO 00/588. All genotype samples and HBsAg mutants were reactive with the Access HBsAg assay. Seroconversion panels tested showed no significant difference with the reference method. Sensitivity for subjects with known HBV infection was 100%. No interference with potentially cross-reactive infections was observed after confirmatory testing. Specificity was 99.96% (100% after confirmatory testing) in a blood donor population and 99.5% (100% after confirmatory testing) in a hospitalized population. Excellent separation of positive and negative populations was observed. CONCLUSIONS: The Access HBsAg and HBsAg Confirmatory assays meet all clinical and analytical performance requirements of assays for the detection of HBsAg

Rapid Probing of Biological Surfaces with a Sparse-Matrix Peptide Library

Finding unique peptides to target specific biological surfaces is crucial to basic research and technology development, though methods based on biological arrays or large libraries limit the speed and ease with which these necessary compounds can be found. We reasoned that because biological surfaces, such as cell surfaces, mineralized tissues, and various extracellular matrices have unique molecular compositions, they present unique physicochemical signatures to the surrounding medium which could be probed by peptides with appropriately corresponding physicochemical properties. To test this hypothesis, a naïve pilot library of 36 peptides, varying in their hydrophobicity and charge, was arranged in a two-dimensional matrix and screened against various biological surfaces. While the number of peptides in the matrix library was very small, we obtained “hits” against all biological surfaces probed. Sequence refinement of the “hits” led to peptides with markedly higher specificity and binding activity against screened biological surfaces. Genetic studies revealed that peptide binding to bacteria was mediated, at least in some cases, by specific cell-surface molecules, while examination of human tooth sections showed that this method can be used to derive peptides with highly specific binding to human tissue

Facteurs associés au maintien dans le poste de travail après un épisode d’absence : résultats de l’étude MAPOST des médecins du travail du groupe La Poste

International audienceObjective. Identify job factors associated to return to work, especially age, among postal workers after a work absence due to health reasons. Methods. In 2015, 32 La Poste occupational physicians conducted a cross-sectional descriptive epidemiological study within 477 postmen over 49 years and 339 of postmen aged between 40 and 49 years old. The main variable of interest is how to stay in work after a sickness absence for more than 30 days. The explanatory variables are personal, medical and occupational factors. Perceived health, perceived physical constraints and relational factors were scored. Multivariate statistical analysis was done by multinomial logistic regression. Results. At the time of medical visit, half of the workers can return to work on their job, 40% can return to work with a reorganized job, 6% reclassified to another job and 4% cannot return to work. The mean total duration of the absence episode is 120 days. In multivariate analysis, the variables significantly associated with a higher risk of having a job arrangement are: age; a cause of absence workrelated; a period of sick leave of more than 90 days; a disability situation; a perceived poor health. Variables significantly associated with a higher risk of reclassification are: more than 90 days of sick leave; a cause of absence work-related; a disability situation; a poor psychosocial score; a perceived poor health. Conclusion. It is possible to identify the predictive factors of return to work after a sickness absence through simple questions and therefore to find solutions to favor the return to work on the medical as well as on the professional levels. (C) 2018 Elsevier Masson SAS. All rights reserved.Objectif. Identifier les facteurs de maintien dans l’emploi, notamment en lien avec l’âge, chez les postiers reprenant le travail après un arrêt de travail pour raison de santé.Méthodes. En 2015, 32 médecins du travail du groupe La Poste ont réalisé une étude épidémiologique descriptive transversale chez 477 de postiers de plus de 49 ans et 339 postiers âgés de 40 à 49 ans ayant subi un arrêt de travail pour raison de santé. La variable principale d’intérêt est les modalités du maintien dans le poste de travail après un arrêt de plus de 30 jours. Les variables explicatives sont les facteurs personnels, médicaux et professionnels. La santé perçue, les contraintes physiques ressenties et les facteurs relationnels ont fait l’objet de scores. L’analyse statistique multivariée a été faite par une régression logistique multinomiale.Résultats. Au moment de la visite de reprise du travail, la moitié des agents peuvent reprendre le travail sur leur poste, 40 % peuvent reprendre leur poste avec un aménagement, 6 % en étant reclassés sur un autre poste et 4 % ne peuvent pas reprendre le travail. En moyenne, la durée totale du dernier arrêt de travail est de 120 jours. En analyse multivariée, les variables significativement associées à un risque plus élevé de nécessiter un aménagement de poste sont : l’âge ; une cause d’arrêt dû au travail ; une durée d’arrêt de travail supérieure à 90 jours ; le fait d’être en situation de handicap ; avoir une santé perçue dégradée. Les variables significativement associées à un risque plus élevé de nécessité de reclassement sont : une durée d’arrêt de travail supérieure à 90 jours ; une cause d’arrêt dû au travail ; le fait d’être en situation de handicap ; avoir un mauvais score psychosocial ; avoir une santé perçue dégradée.Conclusion. Il est possible d’identifier les facteurs prédictifs d’un aménagement de poste ou d’un reclassement à partir de questions simples ce qui permet de réfléchir à des solutions pour favoriser le maintien dans leur poste de travail sur le plan médical comme sur le plan professionnel

Exposure of adults to extremely low frequency magnetic field in France: results of the EXPERS study

Assessing the exposure of adults to magnetic field is a central point in the context of epidemiological studies. The EXPERS study is the first study at national scale in Europe with measurements of personal exposure to extremely low frequency magnetic fields, involving 1046 French adults with 24 h personal measurements. The proportion of adults with a 24 h AM of ≥ 1 µT was 2.1% for all adults and 0.3% for adults for which no alarm clock was identified, as this requirement of the measurement protocol was sometimes not respected. The alarm clocks were the main variable linked to the adults’ exposure measurements. The vicinity of the home to a high voltage power line increased the magnetic field exposure. However, only 1.7% of the adults were living close to a 63 to 400 kV overhead line, and only one of them had a personal exposure ≥ 1 μT with an AM of 1.1 μT. The exposure of adults was also correlated with some characteristics of the home and its environment, and some durations of activities, such as the duration of work and the duration in rail transport. The distribution of adults’ personal exposure was significantly different from the distribution of exposure during sleep, and from the distribution of exposure assessed from measurements during sleep and work. This highlights the complexity of the exposure assessment in epidemiological studies