The Home Microbiome and Childhood Asthma

BACKGROUND: Exposure to microorganisms has repeatedly been found to influence the development of atopic diseases, such as asthma. This relationship has been best understood as an inverse correlation between microbial diversity and atopic disease. Innovative techniques have recently been developed that can more comprehensively characterize microbial communities. OBJECTIVE: To characterize the home microbiota of asthmatics and non-asthmatics utilizing 16S rRNA based phylogenetic analysis by microarray technology METHODS: This cross-sectional study utilized dust samples collected as part of the Kansas City Safe and Healthy Homes Program. DNA was extracted from home dust and bacterial 16S rRNA genes amplified. Bacterial products were hybridized to the PhyloChip Array and scanned using a GeneArray scanner. The Adonis test was used to determine significant differences in the whole microbiome. Welch's t-test was used to determine significant abundance differences and genus-level richness differences. RESULTS: 1741 operational taxonomic units (OTUs) were found in at least one sample. Bacterial genus richness did not differ in the homes of asthmatics and non-asthmatics (p=0.09). The microbial profile was significantly different between the two groups of homes (p=0.025). All of the top 12 OTUs with significant abundance differences were increased in homes of asthmatic children and belonged to one of the five phyla (p=0.001 to p=7.2 x 10-6). Nearly half of significant abundance differences belonged to the phylum Cyanobacteria or Proteobacteria. CONCLUSIONS: These results suggest that home dust has a characteristic microbiota which is disturbed in the homes of asthmatics, resulting in a particular abundance of Cyanobacteria and Proteobacteria. Further investigations are needed which utilize high throughput technology to further clarify how home microbial exposures influence human health and disease

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements