Claire E. Wainwright

Exotic species display greater germination plasticity and higher germination rates than native species across multiple cues

Rapid germination or flexible germination cues may be key traits that facilitate the invasion of exotic plant species in new environments. We investigated whether robustness or plasticity in response to environmental cues were more commonly exhibited by exotic than native species during germination, evidenced by (1) exhibiting consistently greater germination rate under a variety of conditions (robustness), or (2) increasing germination rate more strongly than native species in response to favorable conditions (plasticity). We conducted growth chamber germination trials of 12 native and 12 exotic species common to coastal sage scrub, a shrub-dominated Mediterranean-type ecosystem in California. Time to germination and percentage germination were recorded in response to variation in three environmental cues: temperature, day length, and soil moisture. Exotic species, especially annuals, displayed consistently higher germination percentages and more rapid germination than native species. Exotic germination percentages also responded more strongly when conditions were favorable (warm temperatures and high soil moisture), and germinated earlier than natives when conditions were indicative of typical growing season conditions in Mediterranean ecosystems (short day length and cool temperatures). Exotic species had more rapid and prolific germination across a variety of environmental cues and in response to increased resource availability compared with native species, indicating both germination plasticity and robustness. These traits may enable colonization of novel environments, particularly if they allow exotic species to establish earlier in the growing season than native species, setting the stage for seasonal priority effects.

The changing prevalence of pulmonary infection in adults with cystic fibrosis: A longitudinal analysis.

BACKGROUND Increased patient longevity and aggressive antibiotic treatment are thought to impact on the microbial composition of the airways of adults with cystic fibrosis (CF). In this study, we sought to determine if a temporal change in the airway microbiology of adults with CF has occurred over time. METHODS Longitudinal analysis of sputum microbiology results was undertaken on patients attending a large adult CF centre. Clinical status and health outcomes of transitioning patients were also assessed. RESULTS A decrease in the prevalence of Pseudomonas aeruginosa, Staphylococcus aureus, Burkholderia cepacia complex and Aspergillus spp. (p=0.001, p<0.001, p=0.002 and p<0.001, respectively) occurred. Improvements in lung function among transitioning patients infected with P. aeruginosa were observed. CONCLUSION Overtime, a decline in the prevalence of many CF airway pathogens has occurred. Significantly, an incremental improvement in lung function was reported for transitioning patients with current P. aeruginosa infections.

CFTR-dependent defect in alternatively-activated macrophages in cystic fibrosis

BACKGROUND The role of the macrophages in cystic fibrosis (CF) lung disease has been poorly studied. We hypothesized that alternatively activated M2 macrophages are abnormal in CF lung disease. METHODS Blood samples were collected from adults (n=13) children (n=27) with CF on admission for acute pulmonary exacerbation and when clinically stable. Monocytes were differentiated into macrophages and polarized into classical (M1) and alternatively-activated (M2) phenotypes, function determined ex-vivo and compared with healthy controls. RESULTS In the absence of functional cystic fibrosis trans-membrane conductance regulator (CFTR), either naturally in patients with CF or induced with CFTR inhibitors, monocyte-derived macrophages do not respond to IL-13/IL-4, fail to polarize into M2s associated with a post-transcriptional failure to produce and express IL-13Rα1 on the macrophage surface Polarization to the M1 phenotype was unaffected. CONCLUSIONS CFTR-dependent imbalance of macrophage phenotypes and functions could contribute to the exaggerated inflammatory response seen in CF lung disease.

Effects of exotic annual grass litter and local environmental gradients on annual plant community structure

Exotic annual grasses have been introduced into many semi-arid ecosystems worldwide, often to the detriment of native plant communities. The accumulation of litter from these grasses (i.e. residual dry biomass) has been demonstrated to negatively impact native plant communities and promote positive feedbacks to exotic grass persistence. More targeted experiments are needed, however, to determine the relative impact of exotic grass litter on plant community structure across local environmental gradients. We experimentally added exotic grass litter to annual forb-dominated open woodland communities positioned along natural canopy cover gradients in southwest Western Australia. These communities are an important component of this region’s plant biodiversity hotspot and are documented to be under threat from exotic annual grasses. After a one-year treatment period, we measured the effects of exotic grass litter, soil properties, and canopy cover on native and exotic species richness and abundance, as well as common species’ biomass and abundances. Plant community structure was more strongly influenced by soil properties and canopy cover than by grass litter. Total plant abundances per plot, however, were significantly lower in litter addition plots than control plots, a trend driven by native species. Exotic grass litter was also associated with lower abundances of one very common native species: Waitzia acuminata. Our results suggest that exotic grass litter limits the establishment of some native species in this system. Over multiple years, these subtle impacts may contribute substantially to the successful advancement of exotic species into this system, particularly in certain microenvironments.

Year in review 2015: interstitial lung disease, pulmonary vascular disease, pulmonary function, sleep and ventilation, cystic fibrosis and paediatric lung disease

Keywords: interstitial lung disease; lung function; paediatric lung disease; pulmonary vascular disease; sleep

Diverse outcomes of species interactions in an invaded annual plant community

Aims Despite acknowledgement that interactions among native and exotic species are important for determining the structure and diversity of novel communities, directed experiments using multiple exotics from the same system are rare. Recent observational studies have highlighted distinct ways that exotic species interface with resident natives across invaded communities. The correlative nature of these studies, however, has provided few details about the mechanisms driving distinct interaction outcomes within the same communities. Our aim was to determine how three exotic annual plant species with distinct relationships with local plant diversity impact the performance of a co-occurring native annual in the York gum–jam woodlands of Western Australia. Methods We grew species in experimental communities in growth chambers at varying total planting densities to assess how interaction outcomes varied among natives and exotics across a gradient of competition intensity. We measured a variety of performance responses, including survival, biomass and population-level and individuallevel reproductive investment. Important Findings Overall, the effects of interspecific versus intraspecific competition on performance varied with the identity and density of exotic competitors. The exploitative exotic grass Bromus madritensis was dominant in polyculture, whereas the diminutive grass Pentameris airoides conferred weak intraspecific competition and interspecific facilitation on native Waitzia nitida. The exotic broadleaf forb, Hypochaeris glabra, suppressed growth and survival of W. nitida, while W. nitida had weakly negative, neutral or positive effects on all exotics. These outcomes highlight the complexity of interactions impacting the diversity, stability and structure of novel plant communities. As few of these communities contain a single exotic species, understanding the competitive dynamics occurring in diverse novel communities is critical for their conservation and restoration.

Year in review 2016: Interstitial lung disease, pulmonary vascular disease, pulmonary function, paediatric lung disease, cystic fibrosis and sleep

Department of Respiratory and Sleep Medicine, Royal Prince Alfred Hospital, Central Clinical School, University of Sydney, Sydney, New South Wales, School of Medicine, Lady Cilento Children’s Hospital, University of Queensland, Brisbane, Queensland, Australia, Pulmonary Hypertension Department, Royal Brompton Hospital and Imperial College, London, UK and Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia, Kelowna, British Columbia, Canada

Inhaled Corticosteroids and Respiratory Infections in Children With Asthma: A Meta-analysis

Meta-analysis of 31 randomized trials reveals that regular use of ICS may not increase risk of pneumonia or other respiratory infections in children with asthma. CONTEXT: Inhaled corticosteroids (ICS) are associated with an increased risk of pneumonia in adult patients with chronic obstructive pulmonary disease. OBJECTIVE: To assess the association between ICS use and risk of pneumonia and other respiratory infections in children with asthma. DATA SOURCES: We searched PubMed from inception until May 2015. We also searched clinicaltrials.gov and databases of pharmaceutical manufacturers. STUDY SELECTION: We selected randomized trials that compared ICS with placebo for at least 4 weeks in children with asthma. DATA EXTRACTION: We included 39 trials, of which 31 trials with 11 615 patients contributed data to meta-analyses. RESULTS: The incidence of pneumonia was 0.58% (44/7465) in the ICS group and 1.51% (63/4150) in the placebo group. The meta-analysis of 9 trials that revealed at least 1 event of pneumonia revealed a reduced risk of pneumonia in patients taking ICS (risk ratio [RR]: 0.65; 95% confidence interval [CI]: 0.44 to 0.94). Using risk difference as effect measure, the meta-analysis including all 31 trials revealed no significant difference in the risk of pneumonia between the ICS and placebo groups (risk difference: –0.1%; 95% CI: –0.3% to 0.2%). No significant association was found between ICS and risk of pharyngitis (RR: 1.01; 95% CI: 0.87 to 1.18), otitis media (RR: 1.07; 95% CI: 0.83 to 1.37), and sinusitis (RR: 0.89; 95% CI: 0.76 to 1.05). LIMITATIONS: Lack of clearly defined criteria for respiratory infections and possible publication bias. CONCLUSIONS: Regular use of ICS may not increase the risk of pneumonia or other respiratory infections in children with asthma.

Particle and bioaerosol characteristics in a paediatric intensive care unit

Abstract The paediatric intensive care unit (PICU) provides care to critically ill neonates, infants and children. These patients are vulnerable and susceptible to the environment surrounding them, yet there is little information available on indoor air quality and factors affecting it within a PICU. To address this gap in knowledge we conducted continuous indoor and outdoor airborne particle concentration measurements over a two-week period at the Royal Childrens Hospital PICU in Brisbane, Australia, and we also collected 82 bioaerosol samples to test for the presence of bacterial and viral pathogens. Our results showed that both 24-hour average indoor particle mass (PM10) (0.6–2.2μgm−3, median: 0.9μgm−3) and submicrometer particle number (PN) (0.1–2.8×103 pcm−3, median: 0.67×103 pcm−3) concentrations were significantly lower (p<0.01) than the outdoor concentrations (6.7–10.2μgm−3, median: 8.0μgm−3 for PM10 and 12.1–22.2×103 pcm−3, median: 16.4×103 pcm−3 for PN). In general, we found that indoor particle concentrations in the PICU were mainly affected by indoor particle sources, with outdoor particles providing a negligible background. We identified strong indoor particle sources in the PICU, which occasionally increased indoor PN and PM10 concentrations from 0.1×103 to 100×103 pcm−3, and from 2μgm−3 to 70μgm−3, respectively. The most substantial indoor particle sources were nebulization therapy, tracheal suction and cleaning activities. The average PM10 and PN emission rates of nebulization therapy ranged from 1.29 to 7.41mgmin−1 and from 1.20 to 3.96pmin−1 ×1011, respectively. Based on multipoint measurement data, it was found that particles generated at each location could be quickly transported to other locations, even when originating from isolated single-bed rooms. The most commonly isolated bacterial genera from both primary and broth cultures were skin commensals while viruses were rarely identified. Based on the findings from the study, we developed a set of practical recommendations for PICU design, as well as for medical and cleaning staff to mitigate aerosol generation and transmission to minimize infection risk to PICU patients.

A Novel Method and Its Application to Measuring Pathogen Decay in Bioaerosols from Patients with Respiratory Disease

This work aimed to develop an in vivo approach for measuring the duration of human bioaerosol infectivity. To achieve this, techniques designed to target short-term and long-term bioaerosol aging, were combined in a tandem system and optimized for the collection of human respiratory bioaerosols, without contamination. To demonstrate the technique, cough aerosols were sampled from two persons with cystic fibrosis and chronic Pseudomonas aeruginosa infection. Measurements and cultures from aerosol ages of 10, 20, 40, 900 and 2700 seconds were used to determine the optimum droplet nucleus size for pathogen transport and the airborne bacterial biological decay. The droplet nuclei containing the greatest number of colony forming bacteria per unit volume of airborne sputum were between 1.5 and 2.6 μm. Larger nuclei of 3.9 μm, were more likely to produce a colony when impacted onto growth media, because the greater volume of sputum comprising the larger droplet nuclei, compensated for lower concentrations of bacteria within the sputum of larger nuclei. Although more likely to produce a colony, the larger droplet nuclei were small in number, and the greatest numbers of colonies were instead produced by nuclei from 1.5 to 5.7 μm. Very few colonies were produced by smaller droplet nuclei, despite their very large numbers. The concentration of viable bacteria within the dried sputum comprising the droplet nuclei exhibited an orderly dual decay over time with two distinct half-lives. Nuclei exhibiting a rapid biological decay process with a 10 second half-life were quickly exhausted, leaving only a subset characterized by a half-life of greater than 10 minutes. This finding implied that a subset of bacteria present in the aerosol was resistant to rapid biological decay and remained viable in room air long enough to represent an airborne infection risk.