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

Urban Productive Landscapes: designing nature for re-acting Neoliberal City

none1noThis publication from Springer "Urban book Series" discusses the effects of Neo-Liberal policies on the transformations of architectural and urban practices and education in the transition from the era of “professionalism” to “post-professionalism.” Further, it develops a political and critical perspective on contemporary practices of architecture and urbanism, their implementation, political effects and social results.In the world of urbanism, architecture and landscape, new paradigms are currently change the way people think about or interact with economic crisis, quality of life and self-made practices. In a scenario where the scale and pace of market-driven urbanization and ephemeral landscapes of pop-up settlements are challenging the notion of permanence as a basic planning principle, the regeneration of the city in the 21th century aims to the definition of multi-level approaches associated with emergent socio-spatial challenges. Many of the most promising ideas in this field are that of the reformulation, reclamation and recycle of variable patterns of open spaces as real generators of urban life. This paper presents a theoretical framework, understanding how urban regeneration processes, through the "bottom up" redevelopment of residual spaces, can represent an attempt to reduce degradation of peri-urban fragile environments and to find environmentally compatible ways of increasing the definition of urban productive landscapes.mixedSommariva E.Sommariva, E