Protocol for bacterial filtration efficiency evaluations of facemask materials using viable bacteria-laden aerosol droplets.

Here, we present a protocol for determining the bacterial filtration efficiencies of facemask materials according to the American Society for Testing and Materials (ASTM) standard F2101-19. We describe steps for reproducibly generating, collecting, and enumerating viable bacteria-laden aerosols containing the bacterial pathogen Staphylococcus aureus. The optimized operating parameters generate 1,700 to 3,000 viable bacteria-laden aerosol droplets between 2.

Unraveling the impact of operational parameters and environmental conditions on the quality of viable bacterial aerosols.

Viable pathogen-laden droplets of consistent quality are essential for reliably assessing the protection offered by facemasks against airborne infections. We identified a significant gap in guidance within standardized tests for evaluating the filtration efficiencies of facemask materials using viable bacteria-laden aerosol droplets. An aerosol platform, built according to the American Society for Testing and Materials standard F2101-19, was used to validate and standardize facemask filtration test procedures.

Dextran Mass Ratio Controls Particle Drying Dynamics in a Thermally Stable Dry Powder Vaccine for Pulmonary Delivery.

Purpose: Thermally stable, spray dried vaccines targeting respiratory diseases are promising candidates for pulmonary delivery, requiring careful excipient formulation to effectively encapsulate and protect labile biologics. This study investigates the impact of dextran mass ratio and molecular weight on activity retention, thermal stability and aerosol behaviour of a labile adenoviral vector (AdHu5) encapsulated within a spray dried mannitol-dextran blend.

Methods: Comparing formulations using 40 kDa or 500 kDa dextran at mass ratios of 1:3 and 3:1 mannitol to dextran, in vitro quantification of activity losses and powder flowability was used to assess suitability for inhalation.

Pulmonary hypertension is attenuated and ventilation-perfusion matching is maintained during chronic hypoxia in deer mice native to high altitude.

Hypoxia at high altitude can constrain metabolism and performance and can elicit physiological adjustments that are deleterious to health and fitness. Hypoxic pulmonary hypertension is a particularly serious and maladaptive response to chronic hypoxia, which results from vasoconstriction and pathological remodeling of pulmonary arteries, and can lead to pulmonary edema and right ventricle hypertrophy. We investigated whether deer mice () native to high altitude have attenuated this maladaptive response to chronic hypoxia and whether evolved changes or hypoxia-induced plasticity in pulmonary vasculature might impact ventilation-perfusion (V-Q) matching in chronic hypoxia.