Carbohydrate vitrification in aerosolized saliva is associated with the humidity-dependent infectious potential of airborne coronavirus.

An accepted murine analogue for the environmental behavior of human SARS coronaviruses was aerosolized in microdroplets of its culture media and saliva to observe the decay of its airborne infectious potential under relative humidity (RH) conditions relevant to conditioned indoor air. Contained in a dark, 10 m3 chamber maintained at 22°C, murine hepatitis virus (MHV) was entrained in artificial saliva particles that were aerosolized in size distributions that mimic SARS-CoV-2 virus expelled from infected humans' respiration. As judged by quantitative PCR, more than 95% of the airborne MHV aerosolized was recovered from microdroplets with mean aerodynamic diameters between 0.56 and 5.6 µm. As judged by its half-life, calculated from the median tissue culture infectious dose (TCID50), saliva was protective of airborne murine coronavirus through a RH range recommended for conditioned indoor air (60% < RH < 40%; average half-life = 60 minutes). However, its average half-life doubled to 120 minutes when RH was maintained at 25%. Saliva microaerosol was dominated by carbohydrates, which presented hallmarks of vitrification without efflorescence at low RH. These results suggest that dehydrating carbohydrates can affect the infectious potential coronaviruses exhibit while airborne, significantly extending their persistence under the drier humidity conditions encountered indoors.

Microbial aerosol liberation from soiled textiles isolated during routine residuals handling in a modern health care setting.

BACKGROUND: A wide variety of specialty textiles are used in health care settings for bedding, clothing, and privacy. The ability of textiles to host or otherwise sequester microbes has been well documented; however, their reciprocal potential for liberating airborne bacteria remains poorly characterized. In response, a multi-season survey of bacterial bioaerosols was conducted in the origin and terminus of residual paths which are specifically designed to isolate soiled hospital textiles as they are moved to laundering. This survey used conventional optical particle counting which incorporated multi-channel fluorescence in conjunction with molecular phylogenetic analyses to characterize the bioaerosols liberated during soiled textile storage--immediately before and after the occupation of a modern hospital. Although outfitted with a HEPA filtration system, the number of airborne particles presenting fluorescing optical signatures consistent with airborne bacteria and fungi significantly increased in textile holding rooms soon after the hospital's commissioning, even though these isolated residual areas rarely host personnel. The bioaerosol liberated during textile storage was characterized using Illumina MiSeq sequencing of bacterial 16S ribosomal ribonucleic acid (rRNA) genes. Gene copies recovered by quantitative PCR from aerosol collected in co-located impingers were consistent with fluorescence gated optical particle counting. RESULTS: The relative abundance patterns of proximal bacterial bioaerosol were such that the air in the origin and terminus of textile storage rooms could not be differentiated once the hospital began processing soiled linens. Genes from microbes typically associating with human skin, feces, and hair--Staphylococcus, Propionibacteria, Corynebacteria, Lactobacillus, and Streptococcus spp.--dominated the aerosol abundance profiles in textile holding rooms, which were generally far less diverse than communities recovered from surfaces in patient rooms. CONCLUSIONS: These results suggest that aerosol partitioning from the routine handling of soiled textiles can contribute to airborne exposures in the health care environment.

A toxicology suite adapted for comparing parallel toxicity responses of model human lung cells to diesel exhaust particles and their extracts.

Epidemiological studies have shown that exposure to airborne particulate matter can be an important risk factor for some common respiratory diseases. While many studies have shown that particulate matter exposures are associated with inflammatory reactions, the role of specific cellular responses in the manifestation of primary hypersensitivities, and the progression of respiratory diseases remains unclear. In order to better understand mechanisms by which particulate matter can exert adverse health effects, more robust approaches to support in vitro studies are warranted. In response to this need, a group of accepted toxicology assays were adapted to create an analytical suite for screening and evaluating the effects of important, ubiquitous atmospheric pollutants on two model human lung cell lines (epithelial and immature macrophage). To demonstrate the utility of this suite, responses to intact diesel exhaust particles, and mass-based equivalent doses of their organic extracts were examined. Results suggest that extracts have the potential to induce greater biological responses than those associated with their colloidal counterpart. Additionally, macrophage cells appear to be more susceptible to the cytotoxic effects of both intact diesel exhaust particles and their organic extract, than epithelial cells tested in parallel. As designed, the suite provided a more robust basis for characterizing toxicity mechanisms than the analysis of any individual assay. Findings suggest that cellular responses to particulate matter are cell line dependent, and show that the collection and preparation of PM and/or their extracts have the potential to impact cellular responses relevant to screening fundamental elements of respiratory toxicity.

Silibinin suppresses CD44 expression in prostate cancer cells.

Prostate cancer (PCa), like most human cancers, features dysregulated CD44 expression. Expression of CD44 standard (CD44s), present in benign epithelium, is lost in PCa while pro-invasive splice variant isoform CD44v7-10 is overexpressed. The role of CD44 in silibinin's anti-growth effects was uncertain. To assess silibinin's effects on CD44 promoter activity, PC-3M PCa cells were transfected with luciferase-CD44 promoter construct 24 h prior to 25-200 muM silibinin treatment for 48 h. Also, cells' expression of CD44 RNA (by qRT-PCR) and protein (Western blot analysis) was studied. Silibinin was further tested preoperatively on a pilot cohort of 6 men with PCa compared with 7 matched placebo-treated men, with immunostaining for CD44v7-10 in their prostates. In PC-3M cells, silibinin dose-dependently inhibited CD44 promoter activity up to 87%, caused a 90% inhibition of total CD44 and 70% decrease in CD44v7-10 RNA, and at the protein level, decreased total CD44 at 100-200 muM dose and decreased CD44v7-10 after 3 days. Silibinin decreased adhesion to hyaluronan and fibronectin. Silibinin at 100-200 muM inhibited Egr-1, a regulator of CD44 promoter activity. Men treated with silibinin did not differ in tissue CD44v7-10 expression. In conclusion, CD44 inhibition is one mechanism by which silibinin reduces PCa tumorigenicity.

MicroRNAs 373 and 520c are downregulated in prostate cancer, suppress CD44 translation and enhance invasion of prostate cancer cells in vitro.

Prostate cancer (PCa), like most human cancers, features dysregulated CD44 expression. It loses expression of CD44 standard (CD44s), present in benign epithelium, and overexpresses a less abundant splice isoform, CD44v7-10. MicroRNAs 373 and 520c putatively regulate CD44. The levels of these two microRNAs were measured in matched benign and malignant patient tissues and in prostate cell lines. The effects of their transfection on CD44 mRNA and protein were documented. Whether these miRNAs act on CD44 promoter, or its 3' untranslated region (UTR), was studied with luciferase reporter constructs and their influences on migration and invasion were determined in PC-3M cells. miR-373 and miR-520c expression were decreased in PCa cell lines and tissues, in proportion to their decreases in total CD44 mRNA. Exogenous miR-373 caused a dose-dependent increase in total CD44 RNA, but a decrease in CD44v7-10 RNA, with an optimal dose at 6 nM. At the protein level, however, both microRNAs suppressed CD44. Both migration and invasion were stimulated by miR-373 and miR-520c. The microRNAs had no effect on the CD44 promoter, but did exhibit 3'UTR binding. In conclusion, miR-373 and miR-520c exert their effect in PCa by preventing the translation of CD44 RNA, rather than by degrading the RNA. Despite this observation, they exert pro-invasive functional effects, as previously described in breast cancer cells. Their effects are mediated by binding CD44 3'UTR.