RIVM Publications Repository: Recent submissions
Now showing items 21-40 of 15820
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Primary SARS-CoV-2 infection in children and adults results in similar Fc-mediated antibody effector function patternsHere, we assessed the development of spike S1-specific serum antibody-dependent cellular phagocytosis (ADCP), complement deposition (ADCD) and natural killer cell activation (ADNKA), alongside specific antibody binding concentrations (IgG, IgA and IgM) and IgG avidity in healthy adults (n = 38, 18-56 years) and children (n = 21, 5-16 years) following primary SARS-CoV-2 infection, with a 10-month longitudinal follow-up. Differences between groups were assessed using a nonparametric Kruskal-Wallis test with Dunn's multiple comparisons test.
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Regional variation in the role of humidity on city-level heat-related mortalityThe rising humid heat is regarded as a severe threat to human survivability, but the proper integration of humid heat into heat-health alerts is still being explored. Using state-of-the-art epidemiological and climatological datasets, we examined the association between multiple heat stress indicators (HSIs) and daily human mortality in 739 cities worldwide. Notable differences were observed in the long-term trends and timing of heat events detected by HSIs. Air temperature (Tair) predicts heat-related mortality well in cities with a robust negative Tair-relative humidity correlation (CT-RH). However, in cities with near-zero or weak positive CT-RH, HSIs considering humidity provide enhanced predictive power compared to Tair. Furthermore, the magnitude and timing of heat-related mortality measured by HSIs could differ largely from those associated with Tair in many cities. Our findings provide important insights into specific regions where humans are vulnerable to humid heat and can facilitate the further enhancement of heat-health alert systems.
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Determination of Nicotine Protonation State in E-Liquids by Low-Resolution Benchtop NMR SpectroscopyOver several years, e-liquids with "nicotine salts" have gained considerable popularity. These e-liquids have a low pH, at which nicotine occurs mostly in its monoprotonated form. Manufacturers usually accomplish this by the addition of an organic acid, such as levulinic acid, benzoic acid, or lactic acid. Nicotine in its protonated form can be more easily inhaled, enhancing the addictiveness and attractiveness of products. Several techniques have been described for measuring the protonation state of nicotine in e-liquids. However, nuclear magnetic resonance (NMR) spectroscopy is particularly suited for this purpose because it can be performed on unaltered e-liquids. In this article, we demonstrate the suitability of a benchtop NMR (60 MHz) instrument for determining the protonation state of nicotine in e-liquids. The method is subsequently applied to measure the protonation state of 33 commercially available e-liquids and to investigate whether the vaping process alters the protonation state of nicotine. For this purpose, the protonation state in the condensed aerosol obtained by automated vaping of different e-liquids was compared with that of the original e-liquids. Two distinct populations were observed in the protonation state of nicotine in commercial e-liquids: free-base (fraction of free-base nicotine αfb > 0.80) and protonated (αfb < 0.40). For 30 e-liquids out of 33, the information on the packaging regarding the presence of nicotine salt was in agreement with the observed protonation state. Three e-liquids contained nicotine salt, even though this was not stated on the packaging. Measuring the protonation state of nicotine before and after (machine) vaping revealed that the protonation state of e-liquids is not affected by vaping. In conclusion, it is possible to determine the nicotine protonation state with the described method. Two clusters can be distinguished in the protonation state of commercial e-liquids, and the protonation state of nicotine remains unchanged after vaping.