Demographic science aids in understanding the spread and fatality rates of COVID-19

Governments around the world must rapidly mobilize and make difficult policy decisions to mitigate the coronavirus disease 2019 (COVID-19) pandemic. Because deaths have been concentrated at older ages, we highlight the important role of demography, particularly, how the age structure of a population may help explain differences in fatality rates across countries and how transmission unfolds. We examine the role of age structure in deaths thus far in Italy and South Korea and illustrate how the pandemic could unfold in populations with similar population sizes but different age structures, showing a dramatically higher burden of mortality in countries with older versus younger populations. This powerful interaction of demography and current age-specific mortality for COVID-19 suggests that social distancing and other policies to slow transmission should consider the age composition of local and national contexts as well as intergenerational interactions. We also call for countries to provide case and fatality data disaggregated by age and sex to improve real-time targeted forecasting of hospitalization and critical care needs

Effects of Human Choices on Characteristics of Urban Ecosystems

Most urban ecology in cities remains an ecology in cities rather than an ecology of cities. Accomplishing the latter requires the inclusion of humans within the concept of ecosystem, both how humans alter the properties of urban ecosystems and how these alterations in turn influence human well-being. These influences are both direct (e.g., physiological and psychological influences on the human organism) and indirect, by influencing ecosystem sustainability. For the 2007 ESA meeting, Larry Baker, Loren Byrne, Jason Walker, and Alex Felson organized a symposium to address the relationships among human choices and urban ecosystems. In the introductory talk of this symposium, these authors discussed how the cumulative effect of individual household choices can have major effects on the properties of urban ecosystems

The effect of risk of misstatement and workload pressure on the choice of workpaper review format

Paper presented at the 2007 International Symposium on Audit Research, Shanghai, China.The advent of electronic communication and electronic workpapers at audit firms has provided workpaper reviewers with options of how to interact with their audit team. Concurrently, other review formats have developed that rely more on in-person communication (e.g., review-by-interview). Prior research indicates that in-person discussion during review results in qualitatively different workpapers and judgments than when the reviewer interacts with the workpaper preparer electronically. As reviewers typically have discretion over how to conduct their reviews, the choice of review format can be viewed as a controllable audit input. Thus, the reviewer’s choice of review format could impact the quality of the audit review team’s work. Our study extends the audit review process literature by examining reviewers’ choice of the form of their reviews and by considering factors that influence that choice. Specifically, we examine the effect of misstatement risk and workload pressure on this choice. We find that misstatement risk and workload pressure affect reviewers’ review mode choices, with both those facing low risk and those under high pressure more likely to perform their reviews electronically. Further, risk and workload pressure interact to affect reviewers’ likelihood of choosing to review electronically. Results indicate that misstatement risk moderates the effect of workload pressure such that, when risk is high, the effect of workload pressure is reduced. Our findings provide insight to firms and regulators regarding the impact of misstatement risk and workload pressure on how audit workpaper reviewers conduct their reviews. These issues are particularly relevant in light of recent changes in the regulatory environment that both emphasize the auditor’s role in detecting fraud/misstatements and exacerbate traditional workload pressures during busy times of the year

The Role of luxS in the Middle Ear Streptococcus pneumoniae Isolate 947

The LuxS protein, encoded by luxS, is required for the production of autoinducer 2 (AI-2) in Streptococcus pneumoniae. The AI-2 molecule serves as a quorum sensing signal, and thus regulates cellular processes such as carbohydrate utilisation and biofilm formation, as well as impacting virulence. The role of luxS in S. pneumoniae biology and lifestyle has been predominantly assessed in the laboratory strain D39. However, as biofilm formation, which is regulated by luxS, is critical for the ability of S. pneumoniae to cause otitis media, we investigated the role of luxS in a middle ear isolate, strain 947. Our results identified luxS to have a role in prevention of S. pneumoniae transition from colonisation of the nasopharynx to the ear, and in facilitating adherence to host epithelial cells.Alexandra Tikhomirova, Erin B. Brazel, Kimberley T. McLean, Hannah N. Agnew, James C. Paton and Claudia Trappett

To make or take: bacterial lipid homeostasis during Infection

Bacterial fatty acids are critical components of the cellular membrane. A shift in environmental conditions or in the bacterium’s lifestyle may result in the requirement for a distinct pool of fatty acids with unique biophysical properties. This can be achieved by the modification of existing fatty acids or via de novo synthesis. Furthermore, bacteria have evolved efficient means to acquire these energy-rich molecules from their environment. However, the balance between de novo fatty acid synthesis and exogenous acquisition during pathogenesis is poorly understood. Here, we studied the mouse fatty acid landscape prior to and after infection with Acinetobacter baumannii, a Gram-negative, opportunistic human pathogen. The lipid fluxes observed following infection revealed fatty acid- and niche-specific changes. Lipidomic profiling of A. baumannii isolated from the pleural cavity of mice identified novel A. baumannii membrane phospholipid species and an overall increased abundance of unsaturated fatty acid species. Importantly, we found that A. baumannii relies largely upon fatty acid acquisition in all but one of the studied niches, the blood, where the pathogen biosynthesizes its own fatty acids. This work is the first to reveal the significance of balancing the making and taking of fatty acids in a Gram-negative bacterium during infection, which provides new insights into the validity of targeting fatty acid synthesis as a treatment strategy.Felise G. Adams, Claudia Trappetti, Jack K. Waters, Maoge Zang, Erin B. Brazel, James C. Paton, Marten F. Snel, Bart A. Eijkelkam

Streptococcus pneumoniae Strains Isolated From a Single Pediatric Patient Display Distinct Phenotypes

Streptococcus pneumoniae is the leading cause of bacterial paediatric meningitis after the neonatal period worldwide, but the bacterial factors and pathophysiology that drive pneumococcal meningitis are not fully understood. In this work, we have identified differences in raffinose utilization by S. pneumoniae isolates of identical serotype and sequence type from the blood and cerebrospinal fluid (CSF) of a single pediatric patient with meningitis. The blood isolate displayed defective raffinose metabolism, reduced transcription of the raffinose utilization pathway genes, and an inability to grow in vitro when raffinose was the sole carbon source. The fitness of these strains was then assessed using a murine intranasal infection model. Compared with the CSF isolate, mice infected with the blood isolate displayed higher bacterial numbers in the nose, but this strain was unable to invade the ears of infectedmice. A premature stop codon was identified in the aga gene in the raffinose locus, suggesting that this protein likely displays impaired alpha-galactosidase activity. These closely related strains were assessed by Illumina sequencing, which did not identify any single nucleotide polymorphisms (SNPs) between the two strains. However, these wider genomic analyses identified the presence of an alternative alpha-galactosidase gene that appeared to display altered sequence coverage between the strains, which may account for the observed differences in raffinose metabolic capacity. Together, these studies support previous findings that raffinose utilization capacity contributes to disease progression, and provide insight into a possible alternative means by which perturbation of this pathway may influence the behavior of pneumococci in the host environment, particularly in meningitis.Hannah N. Agnew, Erin B. Brazel, Alexandra Tikhomirova, Mark van der Linden, Kimberley T. McLean, James C. Paton, and Claudia Trappett