Evolution of virulence in opportunistic pathogens: generalism, plasticity, and control

Standard virulence evolution theory assumes that virulence factors are maintained because they aid parasitic exploitation, increasing growth within and/or transmission between hosts. An increasing number of studies now demonstrate that many opportunistic pathogens (OPs) do not conform to these assumptions, with virulence factors maintained instead because of advantages in non-parasitic contexts. Here we review virulence evolution theory in the context of OPs and highlight the importance of incorporating environments outside a focal virulence site. We illustrate that virulence selection is constrained by correlations between these external and focal settings and pinpoint drivers of key environmental correlations, with a focus on generalist strategies and phenotypic plasticity. We end with a summary of key theoretical and empirical challenges to be met for a fuller understanding of OPs

Shear thickening in densely packed suspensions of spheres and rods confined to few layers

We investigate confined shear thickening suspensions for which the sample thickness is comparable to the particle dimensions. Rheometry measurements are presented for densely packed suspensions of spheres and rods with aspect ratios 6 and 9. By varying the suspension thickness in the direction of the shear gradient at constant shear rate, we find pronounced oscillations in the stress. These oscillations become stronger as the gap size is decreased, and the stress is minimized when the sample thickness becomes commensurate with an integer number of particle layers. Despite this confinement-induced effect, viscosity curves show shear thickening that retains bulk behavior down to samples as thin as two particle diameters for spheres, below which the suspension is jammed. Rods exhibit similar behavior commensurate with the particle width, but they show additional effects when the thickness is reduced below about a particle length as they are forced to align; the stress increases for decreasing gap size at fixed shear rate while the shear thickening regime gradually transitions to a Newtonian scaling regime. This weakening of shear thickening as an ordered configuration is approached contrasts with the strengthening of shear thickening when the packing fraction is increased in the disordered bulk limit, despite the fact that both types of confinement eventually lead to jamming.Comment: 21 pages, 14 figures. submitted to the Journal of Rheolog

Development of catecholamine and cortisol stress responses in zebrafish.

Both adrenal catecholamines and steroids are known to be involved in the stress response, immune function, blood pressure and energy homeostasis. The response to stress is characterized by the activation of the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic-adrenomedullary system, though the correlation with activation and development is not well understood. We evaluated the stress response of both cortisol and catecholamines during development in zebrafish. Zebrafish at two different stages of development were stressed in one of two different ways and cortisol and catecholamine were measured. Cortisol was measured by enzyme immune assay and catecholamine was measured by ELISA. Our results show that stress responses are delayed until after the synthesis of both cortisol and catecholamines. These observations suggest that the development of HPA axis may be required for the acquisition of the stress response for cortisol and catecholamines

Prevalence of Low Energy Availability in Collegiate Female Runners and Implementation of Nutrition Education Intervention

Objective: This study examined the prevalence of low energy availability in a sample of female collegiate athletes (N=25) then delivered nutrition education related to the female athlete triad and assessed change in knowledge and dietary behaviors. Methods: Average energy intake was assessed pre- and post-education using Automated Self-Administered 24- Hour Dietary Recalls. We assessed body composition with multiple-site skinfold measures. Energy expenditure was assessed with accelerometers and a physical activity diary over a 3-day period. A 73-item questionnaire was used to assess knowledge and behavior changes. Results: At baseline, 92% had an index of energy availability /kg of fat free mass/day. 40% of participants were amenorrheic, and 32% had a history of stress fractures. There was an increase in summed nutrition knowledge, post-nutrition education (p=0.001), but no increase in caloric intake (p=0.979). Conclusion: Low energy availability was common in this sample of female collegiate track athletes, but did not improve with a targeted intervention

Review of United States and International Formaldehyde Emission Regulations for Interior Wood Composite Panels

This article compares and contrasts formaldehyde emission regulations for interior wood composite panels in the US, the European Union, Japan, and China. Historical context, product-specific emission limits, test methods, and product certification requirements are detailed for each emission standard. In particular, the recently enacted California Air Resources Board (CARB) formaldehyde regulation is compared with established international formaldehyde regulations and differences in four key areas, emission limits, documentation, deconstructive testing, and enforcement, are highlighted. Implications of CARB and US Environmental Protection Agency regulatory actions are discussed, and future work is suggested in the rapidly evolving and highly debated arena of formaldehyde emission policy

Factors influencing adults’ immunization practices: a pilot survey study of a diverse, urban community in central Ohio

Abstract Background Adult vaccination rates in the United States are well below recommendations with disparities in race, ethnicity, and education level resulting in even lower rates for these populations. This study aimed to identify the barriers to and perceptions of immunizations in adults in an urban, underserved, multicultural community. Understanding the factors that influence adults’ decisions to receive routinely recommended vaccines will aid health care providers and public health officials to design programs to improve vaccination rates. Methods This cross-sectional, survey-based study was conducted in January 2014 in Columbus, Ohio. Participants were recruited from four urban federally-qualified health centers and four grocery stores affiliated with those clinics. The survey gathered self-reported receipt of immunizations, knowledge about indications for immunizations, and factors influencing decisions to receive an immunization. Data was analyzed in 2014. Descriptive statistics were generated for all survey items and Chi-Square or Fisher’s Exact tests were used as appropriate to test for associations between demographic characteristics and factors influencing immunization decisions. Results The top five factors likely to affect the decision to receive an immunization among the 304 respondents were: “doctor’s recommendation” (80.6 %), “knowing why I should get a vaccine” (78.2 %), “knowing which vaccines I need” (75.5 %), cost (54.2 %), and “concern about getting sick if I get a vaccine” (54.0 %). Significant differences in factors influencing the immunization decision exist among respondents based on ethnicity and education level. For those participants with self-identified diabetes, heart disease, or asthma, less than half were aware that certain immunizations could reduce the risk of complications associated with their disease(s). Conclusions Data from this study may inform and shape patient education programs conducted in clinics, retailers, and communities, as well as advocacy efforts for adult immunizations. Results from this study suggest that patients would respond to programs for promoting vaccine uptake if they focused on benefits and indications for vaccines. The results also highlighted the need for education regarding immunizations for patients with chronic diseases and special indications. The differences in perceptions found between groups can be used to create targeted interventions based on the needs of those patient populations

Avian oncogenesis induced by lymphoproliferative disease virus: a neglected or emerging retroviral pathogen?

Lymphoproliferative disease virus (LPDV) is an exogenous oncogenic retrovirus that induces lymphoid tumors in some galliform species of birds. Historically, outbreaks of LPDV have been reported from Europe and Israel. Although the virus has previously never been detected in North America, herein we describe the widespread distribution, genetic diversity, pathogenesis, and evolution of LPDV in the United States. Characterization of the provirus genome of the index LPDV case from North America demonstrated an 88% nucleotide identity to the Israeli prototype strain. Although phylogenetic analysis indicated that the majority of viruses fell into a single North American lineage, a small subset of viruses from South Carolina were most closely related to the Israeli prototype. These results suggest that LPDV was transferred between continents to initiate outbreaks of disease. However, the direction (New World to Old World or vice versa), mechanism, and time frame of the transcontinental spread currently remain unknown

Hot topics, urgent priorities, and ensuring success for racial/ethnic minority young investigators in academic pediatrics.

BackgroundThe number of racial/ethnic minority children will exceed the number of white children in the USA by 2018. Although 38% of Americans are minorities, only 12% of pediatricians, 5% of medical-school faculty, and 3% of medical-school professors are minorities. Furthermore, only 5% of all R01 applications for National Institutes of Health grants are from African-American, Latino, and American Indian investigators. Prompted by the persistent lack of diversity in the pediatric and biomedical research workforces, the Academic Pediatric Association Research in Academic Pediatrics Initiative on Diversity (RAPID) was initiated in 2012. RAPID targets applicants who are members of an underrepresented minority group (URM), disabled, or from a socially, culturally, economically, or educationally disadvantaged background. The program, which consists of both a research project and career and leadership development activities, includes an annual career-development and leadership conference which is open to any resident, fellow, or junior faculty member from an URM, disabled, or disadvantaged background who is interested in a career in academic general pediatrics.MethodsAs part of the annual RAPID conference, a Hot Topic Session is held in which the young investigators spend several hours developing a list of hot topics on the most useful faculty and career-development issues. These hot topics are then posed in the form of six "burning questions" to the RAPID National Advisory Committee (comprised of accomplished, nationally recognized senior investigators who are seasoned mentors), the RAPID Director and Co-Director, and the keynote speaker.Results/conclusionsThe six compelling questions posed by the 10 young investigators-along with the responses of the senior conference leadership-provide a unique resource and "survival guide" for ensuring the academic success and optimal career development of young investigators in academic pediatrics from diverse backgrounds. A rich conversation ensued on the topics addressed, consisting of negotiating for protected research time, career trajectories as academic institutions move away from an emphasis on tenure-track positions, how "non-academic" products fit into career development, racism and discrimination in academic medicine and how to address them, coping with isolation as a minority faculty member, and how best to mentor the next generation of academic physicians

Shear thickening and jamming in densely packed suspensions of different particle shapes

We investigated the effects of particle shape on shear thickening in densely packed suspensions. Rods of different aspect ratios and non-convex hooked rods were fabricated. Viscosity curves and normal stresses were measured using a rheometer for a wide range of packing fractions for each shape. Suspensions of each shape exhibit qualitatively similar Discontinuous Shear Thickening. The logarithmic slope of the stress/shear-rate relation increases dramatically with packing fraction and diverges at a critical packing fraction phi_c which depends on particle shape. The packing fraction dependence of the viscosity curves for different convex shapes can be collapsed when the packing fraction is normalized by phi_c. Intriguingly, viscosity curves for non-convex particles do not collapse on the same set as convex particles, showing strong shear thickening over a wider range of packing fraction. The value of phi_c is found to coincide with the onset of a yield stress at the jamming transition, suggesting the jamming transition also controls shear thickening. The yield stress is found to correspond with trapped air in the suspensions, and the scale of the stress can be attributed to interfacial tension forces which dramatically increase above phi_c due to the geometric constraints of jamming. The relationship between shear and normal stresses is found to be linear in both the shear thickening and jammed regimes, indicating that the shear stresses come from friction. In the limit of zero shear rate, normal stresses pull the rheometer plates together due to the surface tension of the liquid below phi_c, but push the rheometer plates apart due to jamming above phi_c.Comment: 13 pages, 13 figures. published in Physical Review