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BackgroundSerosurveys are essential to understand SARS-CoV-2 exposure and enable population-level surveillance, but currently available tests need further in-depth evaluation. We aimed to identify testing-strategies by comparing seven seroassays in a population-based cohort.MethodsWe analysed 6,658 samples consisting of true-positives (n=193), true-negatives (n=1,091), and specimens of unknown status (n=5,374). For primary testing, we used Euroimmun-Anti-SARS-CoV-2-ELISA-IgA/IgG and Roche-Elecsys-Anti-SARS-CoV-2; and virus-neutralisation, GeneScript®cPass™, VIRAMED-SARS-CoV-2-ViraChip®, and Mikrogen-recomLine-SARS-CoV-2-IgG, including common-cold CoVs, for confirmatory testing. Statistical modelling generated optimised assay cut-off-thresholds.FindingsSensitivity of Euroimmun-anti-S1-IgA was 64.8%, specificity 93.3%; for Euroimmun-anti-S1-IgG, sensitivity was 77.2/79.8% (manufacturer’s/optimised cut-offs), specificity 98.0/97.8%; Roche-anti-N sensitivity was 85.5/88.6%, specificity 99.8/99.7%. In true-positives, mean and median titres remained stable for at least 90-120 days after RT-PCR-positivity. Of true-positives with positive RT-PCR (recomLine-RBD) were >94.9% sensitive, >98.1% specific. Seasonality had limited effects; cross-reactivity with common-cold CoVs 229E and NL63 in SARS-CoV-2 true-positives was significant.ConclusionOptimised cut-offs improved test performances of several tests. Non-reactive serology in true-positives was uncommon. For epidemiological purposes, confirmatory testing with virus-neutralisation may be replaced with GeneScript®cPass™ or recomLine-RBD. Head-to-head comparisons given here aim to contribute to the refinement of testing-strategies for individual and public health use.

In the first section, an historical summary of analytical chemistry is presented. In ancient history, one function of an analytical chemist was to confirm the identity of noble metals, especially gold. In later times, important inventions and their discoverer were named. Now, in the twenty-first century, analytical chemistry is an interdisciplinary scientific field.Next, the aim and means of analytical chemistry are discussed. For analytical tasks, the chemist has over 6,000 experimental procedures (including sub-specifications) available. The most important procedures are summarized. Moreover analytical problems, such as analyte(s) from complex matrixes, and the necessary purification as well as determination steps are discussed. Quantification measures, such as parts per trillion, are considered. The three analytical phases (pre-analysis, analysis, post-analysis) are presented, and recently developed analytical procedures such as ?Lab on a chip? and the ?omics? sciences are introduced.In the section ?Pre-analysis? different techniques of sample preparation prior to analytical measurement are described. Apart from classic methods, such as crushing and homogenization, extraction techniques such as solidphase extraction, liquid-liquid extraction, and solid-phase microextraction are reviewed. The analytical section is divided into three parts, plus subparts: (i) separation techniques are presented followed by (ii) atomic spectroscopy and (iii) selective analytical chemistry. Each (sub)part begins with a short historical overview.For separation techniques, first the principles of chromatography are described followed by the principles of electrophoresis and capillary electrophoresis. The chromatographic and atomic spectroscopy classifications and techniques are not presented in isolation, as in many analytical textbooks. They are described along with associated coupled techniques. Such coupled techniques are liquid chromatography (LC), gas chromatography (GC), thin-layer chromatography, and ion-exchange chromatography (IEC). LC is often coupled with mass spectrometry (MS, including different ionization techniques such as Thermospray, Fast Atom Bombardment, Particle Beam) or matrix-assisted laser desorption/ionization time-of flight-mass spectrometry (MALDI-TOF-MS). GC is also often coupled with MS. Moreover, derivatization techniques and Headspace GC are presented.In the case of atomic spectroscopy, atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) are presented in more detail. In the section ?selective analytical chemistry,? sensor techniques with ion-selective electrodes and the principles of immunoassays aredescribed. These techniques are primarily for routine and fast analysis of known components in a sample. In most cases the sample preparation steps are easy and rapid compared to, say, the sample preparation steps for gas chromatography.

Introduction The public interest steadily increases in the biological adverse effects caused by components released from resin-based dental restorations. Objective In this study, the cytotoxicity and the genotoxicity were investigated of following released components from dental resin restorations in human gingival fibroblasts (HGF): tetraethyleneglycol dimethacrylate (TEEGDMA), neopentylglycol dimethacrylate (Neopen), diphenyliodoniumchloride (DPIC), triphenyl-stibane (TPSB) and triphenylphosphane (TPP). Methods XTT based cell viability assay was used for cytotoxicity screening of substances. γ-H2AX assay was used for genotoxicity screening. In the γ-H2AX assay, HGFs were exposed to the substances for 6 h. Induced foci represent double DNA strand breaks (DSBs), which can induce ATM-dependent phosphorylation of the histone H2AX. Cell death effects (apoptosis and necrosis), induced by the substances were visually tested by the same investigator using the fluorescent microscope. Results All tested substances induced a dose-dependent loss of viability in HGFs. Following toxicity ranking among the substances at EC50-concentration were found in the XTT assay (mM, mean ± SEM; n = 5): DPIC > Neopen > TPSB > TPP > TEEGDMA. DSB-foci per HGF-cell were obtained, when HGFs were exposed to the EC50-concentration of each substance in the following order (mean ± SEM; n = 3): DPIC > Neopen > TPSB > TPP > TEEGDMA. Multi-foci cells (cells that contain more than 40 foci each) in 80 HGF-cells at EC50-concentration of each substance were found as follow (mean ± SEM; n = 3): DPIC > Neopen > TPP > TPSB > TEEGDMA. Cell apoptosis contained in each substance at EC50-concentration in the following order (mean ± SEM; n = 3): DPIC > Neopen > TPSB > TPP >TEEGDMA. Cell necrosis contained in each substance at EC50-concentration in the following order (mean ± SEM; n = 3): DPIC > Neopen > TPSB > TPP > TEEGDMA. Conclusion Leached components from dental resin restorations can induce DNA DSBs and cell death effects in HGFs.

Clinical chemistry and laboratory medicine can look back over more than 150 years of eventful history. The subject encompasses all the medicinal disciplines as well as the remaining natural sciences. Clinical chemistry demonstrates how new insights from basic research in biochemical, biological, analytical chemical, engineering, and information technology can be transferred into the daily routine of medicine to improve diagnosis, therapeutic monitoring, and prevention. This Review begins with a presentation of the development of clinical chemistry. Individual steps between the drawing of blood and interpretation of laboratory data are then illustrated; here not only are pitfalls described, but so are quality control systems. The introduction of new methods and trends into medicinal analysis is explored, along with opportunities and problems associated with personalized medicine.

Given a set of PSA values, we answer the question: “Is its information content typical for the existence of a prostate cancer, or not?” Our findings support PSA screening.

Clinical chemistry and laboratory medicine can look back over more than 150 years of eventful history. The subject encompasses all the medicinal disciplines as well as the remaining natural sciences. Clinical chemistry demonstrates how new insights from basic research in biochemical, biological, analytical chemical, engineering, and information technology can be transferred into the daily routine of medicine to improve diagnosis, therapeutic monitoring, and prevention. This Review begins with a presentation of the development of clinical chemistry. Individual steps between the drawing of blood and interpretation of laboratory data are then illustrated; here not only are pitfalls described, but so are quality control systems. The introduction of new methods and trends into medicinal analysis is explored, along with opportunities and problems associated with personalized medicine.