Using data from the Environmental Protection Agency's Chemical Speciation Network, we have characterized trends in PM 2.5 transition metals in urban areas across the United States for the period 2001-2016. The metals included in this analysis-Cr, Cu, Fe, Mn, Ni, V, and Zn-were selected based upon their abundance in PM 2.5 , known sources, and links to toxicity. Ten cities were included to provide broad geographic coverage, diverse source influences, and climatology: Atlanta (ATL), Baltimore (BAL), Chicago (CHI), Dallas (DAL), Denver (DEN), Los Angeles (LA), New York City (NYC), Phoenix (PHX), Seattle (SEA), and St. Louis (STL). The concentrations of V and Zn decreased in all ten cities, though the V decreases were more substantial. Cr concentrations increased in cities in the East and Midwest, with a pronounced spike in concentrations in 2013. The National Emissions Inventory was used to link sources with the observed trends; however, the causes of the broad Cr concentration increases and 2013 spike are not clear. Analysis of PM 2.5 metal concentrations in port versus non-port cities showed different trends for Ni, suggesting an important but decreasing influence of marine emissions. The concentrations of most PM 2.5 metals decreased in LA, STL, BAL, and SEA while concentrations of four of the seven metals (Cr, Fe, Mn, Ni) increased in DAL over the same time. Comparisons of the individual metals to overall trends in PM 2.5 suggest decoupled sources and processes affecting each. These metals may have an enhanced toxicity compared to other chemical species present in PM, so the results have implications for strategies to measure exposures to PM and the resulting human health effects.

Previous studies have attempted to characterize the antibody response of individuals to the SARS-CoV-2 virus on a linear peptide level by utilizing peptide microarrays. These studies have helped to identify epitopes that have potential to be used for diagnostic tests to identify infected individuals. The immunological responses of individuals who have received the two most popular vaccines available in the US, the Moderna mRNA-1273 or the Pfizer BNT162b2 mRNA vaccines, have not been characterized. We aimed to identify linear peptides of the SARS-CoV-2 spike protein that elicited high IgG or IgA binding activity and to compare the immunoreactivity of infected individuals to those who received both doses of either vaccine by utilizing peptide microarrays. Our results revealed peptide epitopes of significant IgG binding among recently infected individuals. Some of these peptides are located near variable regions of the receptor binding domains as well as the conserved region in the c-terminal of the spike protein implicated in the high infectivity of SARS-CoV-2. Vaccinated individuals lacked a response to these distinct markers despite the overall antibody binding activity being similar.

A multitude of studies have attempted to characterize the antibody response of individuals to the SARS-CoV-2 virus on a linear peptide level by utilizing peptide microarrays. These studies have helped to identify epitopes that have potential to be used for diagnostic tests to identify infected individuals, however the immunological responses of individuals who have received the currently available mRNA vaccines have not been characterized. We aimed to identify linear peptides of the SARS-CoV-2 spike protein that elicited high IgA or IgG binding activity and compare the immunoreactivity of infected individuals to those who received recommended doses of either the Moderna mRNA-1273 or Pfizer BNT162b2 vaccines by utilizing peptide microarrays. Our results revealed peptide epitopes of significant IgG binding among recently infected individuals, many of which are located near functional domains implicated in the high infectivity of SARS-CoV-2. Vaccinated individuals were found to have less intense antibody binding activity than those acutely infected, yet novel markers of IgG binding were identified in the vaccinated group.