Comparative diagnostic performance of rapid antigen detection tests for COVID-19 in a hospital setting

Background: The availability of accurate and rapid diagnostic tools for COVID-19 is essential for tackling the ongoing pandemic. Our study aimed to quantify the performance of available antigen-detecting rapid diagnostic tests (Ag-RDTs) in a real-world hospital setting. Methods: In this retrospective analysis, the diagnostic performance of 7 Ag-RDTs was compared with real-time reverse transcription quantitative polymerase chain reaction assay in terms of sensitivity, specificity and expected predictive values. Results: A total of 321 matched Ag-RDTreal-time reverse transcription quantitative polymerase chain reaction samples were analyzed retrospectively. The overall sensitivity and specificity of the Ag-RDTs was 78.7% and 100%, respectively. However, a wide range of sensitivity estimates by brand (66.0%–93.8%) and cycle threshold (Ct) cut-off values (Ct <25: 96.2%; Ct 30–35: 31.1%) was observed. The optimal Ct cut-off value that maximized sensitivity was 29. Conclusions: The routine use of Ag-RDTs may be convenient in moderate-to-high intensity settings when high volumes of specimens are tested every day. However, the diagnostic performance of the commercially available tests may differ substantially

Effect of the 2020/21 season influenza vaccine on SARS-CoV-2 infection in a cohort of Italian healthcare workers

Objectives: Healthcare workers (HCWs) are a priority group for seasonal influenza vaccination (SIV). The 2020/21 SIV campaign was conducted during the second wave of the COVID-19 pandemic. Vaccines, including SIV, may exert non-specific protective effects on other infectious diseases which may be ascribable to the concept of trained immunity. The aim of this study was to explore the association between 2020/21 SIV and SARS-CoV-2 positivity in a cohort of Italian HCWs. Methods: In this observational study, a cohort of HCWs employed by a large (ca 5000 employees) referral tertiary acute-care university hospital was followed up retrospectively until the start of the COVID-19 vaccination campaign. The independent variable of interest was the 2020/21 SIV uptake. Both egg-based and cell culture-derived quadrivalent SIVs were available. The study outcome was the incidence of new SARS-CoV-2 infections, as determined by RT-PCR. Multivariable Cox regression was applied in order to discern the association of interest. Results: The final cohort consisted of 2561 HCWs who underwent ≥1 RT-PCR test and accounted for a total of 94,445 person-days of observation. SIV uptake was 35.6%. During the study period, a total of 290 new SARS-CoV-2 infections occurred. The incidence of new SARS-CoV-2 was 1.62 (95% CI: 1.22–2.10) and 3.91 (95% CI: 3.43–4.45) per 1000 person-days in vaccinated and non-vaccinated HCWs, respectively, with an adjusted non-proportional hazard ratio of 0.37 (95% CI: 0.22–0.62). E-values suggested that unmeasured confounding was unlikely to explain the association. Conclusions: A lower risk of SARS-CoV-2 infection was observed among SIV recipients

Geometric numerical schemes for the KdV equation

Geometric discretizations that preserve certain Hamiltonian structures at the discrete level has been proven to enhance the accuracy of numerical schemes. In particular, numerous symplectic and multi-symplectic schemes have been proposed to solve numerically the celebrated Korteweg-de Vries (KdV) equation. In this work, we show that geometrical schemes are as much robust and accurate as Fourier-type pseudo-spectral methods for computing the long-time KdV dynamics, and thus more suitable to model complex nonlinear wave phenomena.Comment: 22 pages, 14 figures, 74 references. Other author's papers can be downloaded at http://www.lama.univ-savoie.fr/~dutykh

On the shape and likelihood of oceanic rogue waves

We consider the observation and analysis of oceanic rogue waves collected within spatio-Temporal (ST) records of 3D wave fields. This class of records, allowing a sea surface region to be retrieved, is appropriate for the observation of rogue waves, which come up as a random phenomenon that can occur at any time and location of the sea surface. To verify this aspect, we used three stereo wave imaging systems to gather ST records of the sea surface elevation, which were collected in different sea conditions. The wave with the ST maximum elevation (happening to be larger than the rogue threshold 1.25H s) was then isolated within each record, along with its temporal profile. The rogue waves show similar profiles, in agreement with the theory of extreme wave groups. We analyze the rogue wave probability of occurrence, also in the context of ST extreme value distributions, and we conclude that rogue waves are more likely than previously reported; the key point is coming across them, in space as well as in time. The dependence of the rogue wave profile and likelihood on the sea state conditions is also investigated. Results may prove useful in predicting extreme wave occurrence probability and strength during oceanic storms

Metabolomic evaluation of NO production in human erythrocytes: an LC-MS/MS method to asses arginine and its metabolites

Experimental studies suggest that red blood cells are involved in nitric oxide (NO) synthesis and delivery. Erythrocytes acts as producers, scavengers and vehicles of NO affecting several physiological processes. NO bioavailability is linked not only to arginine and its metabolic products, ornithine and citrulline, but also to methylarginines which are inhibitors of NO sinthesis. Existing methodologies do not permit a systematic evaluation of the metabolic and biosynthetic pathway of NO in RBC. A metabolomic approach, considering a larger number of compounds involved in NO metabolic pathway, could be important to better understand the role of red blood cells in physiological and pathological conditions. We set up an HPLC-electrospray ionization-tandem mass spectrometry method, to simultaneously detect and quantify arginine metabolome, i.e. arginine, symmetric and asymmetric dimethylarginine, monomethyarginine, ornithine, citrulline. Stable isotope-labelled internal standards have been used to minimize analytical variations before organic protein precipitation of the isolated and lysated erythrocytes. The ion source was operating in positive ion mode and the analytes were detected using multiple reaction monitoring after hydrophilic-interaction chromatography. A 8 min run time allowed the simultaneous evaluation of all the analytes involved in the NO pathway. The chromatograms were free from interferences, the calibration functions were linear and the inter-day CV were<10% for all the analytes. LOQ values make this method suitable for low concentration samples. Our validated LC-MS/MS method might be useful to clarify the role of RBCs in the synthesis of NO and will be of help for studies assessing the involvement of these cells in the regulation of blood flow under physiologic or pathological conditions. Moreover, a simple sample processing without the derivatization step, allows to consider this method a valuable tool for diagnostic evaluation of arginine metabolome in red blood cells and it could be applied in clinical chemistry

Neurohormonal activation is associated with increased levels of plasma matrix metalloproteinase-2 in human heart failure

Aims: Development of heart failure depends on systemic and molecular abnormalities among which are the activation of neurohormonal systems and the increase of matrix metalloproteinases (MMPs). This study assessed the relationship between catecholamines and active MMPs in vivo in patients with severe congestive heart failure (CHF) and in vitro in human cardiac fibroblasts. Methods and results: Forty patients with CHF due to dilated cardiomyopathy, either idiopathic (n = 20) or secondary to ischaemic heart disease (n = 20), were compared with 20 healthy subjects. Plasma MMP-2 and MMP-9 activity, but not TIMP-2, were significantly higher in patients than in controls (median MMP-2, 270 vs. 214 ng/mL, P = 0.006; MMP-9 16.3 vs. 8.7 ng/mL, P < 0.0001). Similarly, noradrenaline, but not adrenaline, was significantly higher in patients (noradrenaline 645 vs. 157 pg/mL, P < 0.0001; adrenaline 86.0 vs. 72.6 pg/mL, P = 0.68). No difference in any parameter was observed between patient groups. The intra-group correlation between MPP-2 and noradrenaline was significant (r = 0.33, P = 0.01); indeed, noradrenaline appear to be a predictor of MMP-2. Moreover, this catecholamine increased MMP-2 in human cardiac fibroblasts. Conclusions: The positive correlation between noradrenaline and MMP-2 in severe CHF patients, together with the in vitro induction of MMP-2 by this catecholamine, suggests a potential biochemical link between noradrenaline and MMP-2