Defining a highly conserved B cell epitope in the receptor binding motif of SARS-CoV-2 spike glycoprotein.

Unlabelled: SARS-CoV-2 mRNA vaccines induce robust and persistent germinal centre (GC) B cell responses in humans. It remains unclear how the continuous evolution of the virus impacts the breadth of the induced GC B cell response. Using ultrasound-guided fine needle aspiration, we examined draining lymph nodes of nine healthy adults following bivalent booster immunization.

Xylazine Pharmacokinetics in Patients Testing Positive for Fentanyl and Xylazine.

Background: The increasing prevalence of xylazine in the illicit drug supply is a growing concern for major health consequences in individuals who use fentanyl mixed with xylazine, but limited data are available regarding the pharmacokinetics of xylazine in humans.

Methods: Xylazine was quantified in serial remnant plasmas collected from 28 patients starting at the initial patient encounter and continuing for up to 52 h from presentation, using LC-MS/MS to calculate the terminal half-life for xylazine. Xylazine metabolites were identified by product ion scanning, and multiple reaction monitoring was used to estimate the relative abundance of xylazine metabolites in 74 collected plasma samples.

Prospective and External Validation of an Ensemble Learning Approach to Sensitively Detect Intravenous Fluid Contamination in Basic Metabolic Panels.

Background: Intravenous (IV) fluid contamination within clinical specimens causes an operational burden on the laboratory when detected, and potential patient harm when undetected. Even mild contamination is often sufficient to meaningfully alter results across multiple analytes. A recently reported unsupervised learning approach was more sensitive than routine workflows, but still lacked sensitivity to mild but significant contamination.

SARS-CoV-2 anti-N antibodies among healthcare personnel without previous known COVID-19.

Objective: To measure SARS-CoV-2 anti-nucleocapsid (anti-N) antibody seropositivity among healthcare personnel (HCP) without a history of COVID-19 and to identify HCP characteristics associated with seropositivity.

Design: Prospective cohort study from September 22, 2020, to March 3, 2022.

Setting: A tertiary care academic medical center.