(18)F-FDG PET may assist decision making in ischemic cardiomyopathy. The PET and Recovery Following Revascularization (PARR 2) trial demonstrated a trend toward beneficial outcomes with PET-assisted management. The substudy of PARR 2 that we call Ottawa-FIVE, described here, was a post hoc analysis to determine the benefit of PET in a center with experience, ready access to (18)F-FDG, and integration with clinical teams.
Included were patients with left ventricular dysfunction and suspected coronary artery disease being considered for revascularization. The patients had been randomized in PARR 2 to PET-assisted management (group 1) or standard care (group 2) and had been enrolled in Ottawa after August 1, 2002 (the date that on-site (18)F-FDG was initiated) (n = 111). The primary outcome was the composite endpoint of cardiac death, myocardial infarction, or cardiac rehospitalization within 1 y. Data were compared with the rest of PARR 2 (PET-assisted management [group 3] or standard care [group 4]).
In the Ottawa-FIVE subgroup of PARR 2, the cumulative proportion of patients experiencing the composite event was 19% (group 1), versus 41% (group 2). Multivariable Cox proportional hazards regression showed a benefit for the PET-assisted strategy (hazard ratio, 0.34; 95% confidence interval, 0.16-0.72; P = 0.005). Compared with other patients in PARR 2, Ottawa-FIVE patients had a lower ejection fraction (25% +/- 7% vs. 27% +/- 8%, P = 0.04), were more often female (24% vs. 13%, P = 0.006), tended to be older (64 +/- 10 y vs. 62 +/- 10 y, P = 0.07), and had less previous coronary artery bypass grafting (13% vs. 21%, P = 0.07). For patients in the rest of PARR 2, there was no significant difference in events between groups 3 and 4. The observed effect of (18)F-FDG PET-assisted management in the 4 groups in the context of adjusted survival curves demonstrated a significant interaction (P = 0.016). Comparisons of the 2 arms in Ottawa-FIVE to the 2 arms in the rest of PARR 2 demonstrated a trend toward significance (standard care, P = 0.145; PET-assisted management, P = 0.057).
In this post hoc group analysis, a significant reduction in cardiac events was observed in patients with (18)F-FDG PET-assisted management, compared with patients who received standard care. The results suggest that outcome may be benefited using (18)F-FDG PET in an experienced center with ready access to (18)F-FDG and integration with imaging, heart failure, and revascularization teams.
Population dynamics are shaped by species interactions with resources, competitors, enemies, and environmental fluctuations that alter the strength of these interactions. We used a food web approach to investigate the population dynamics of an abundant Arctic mosquito species, Aedes nigripes (Diptera: Culicidae). Specifically, we evaluated the importance of bottom-up variation in aquatic biofilms (food) and top-down predation from diving beetles (Colymbetes dolabratus, Coleoptera: Dytiscidae) on mosquito population performance. In spring 2018, we tracked mosquito and predator populations across eight ponds in western Greenland, measured biofilm productivity with standardized samplers, and estimated grazing pressure by invertebrate consumers with an in situ exclosure experiment. We also assessed the quality of biofilms as nutrition for mosquito larvae and evaluated pond attributes that might influence biofilm productivity and food quality. Our results indicated that mosquito population dynamics were more related to resource quality and intraspecific competition than to the density of predaceous diving beetles. Ponds with better quality biofilm tended to have more hatching larvae and those populations experienced higher per capita mortality. This aggregation of larvae in what would otherwise be the best mosquito ponds was enough to produce relatively low fitness. Thus, the landscape would support more mosquitoes if they instead distributed themselves to match predictions of the ideal free distribution. Although mortality rates were highest in ponds with the highest initial densities, the increased mortality was not generally enough to compensate for initial abundance, and 78% of the variation in the density of mosquitoes emerging from ponds was explained by the initial number of larvae in a pond. Resource quality was a strong predictor of consumer abundance, yet there was no evidence that biofilm grazing pressure was greater in ponds where mosquito density was higher. Collectively, our results suggest that mosquito ponds in western Greenland are a mosaic of source and pseudo-sink populations structured by oviposition tendencies, biofilm resource quality, and density-dependent larval mortality.
To examine the effects of 30 hr of sleep loss and continuous cognitive work on performance in a distributed team decision-making environment.
To date, only a few studies have examined the effect of sleep loss on distributed team performance, and only one other to our knowledge has examined the relationship between sleep loss and social-motivational aspects of teams (Hoeksema-van Orden, Gaillard, & Buunk, 1998).
Sixteen teams participated; each comprised 4 members. Three team members made threat assessments on a military surveillance task and then forwarded their judgments electronically to a team leader, who made a final assessment on behalf of the team.
Sleep loss had an antagonistic effect on team decision-making accuracy and decision time. However, the performance loss associated with fatigue attributable to sleep loss was mediated by being part of a team, as compared with performing the same task individually - that is, we found evidence of a "motivational gain" effect in these sleepy teams. We compare these results with those of Hoeksema-van Orden et al. (1998), who found clear evidence of a "social loafing" effect in sleepy teams.
The divergent results are discussed in the context of the collective effort model (Karau & Williams, 1993) and are attributable in part to a difference between independent and interdependent team tasks.
The issues and findings have implications for a wide range of distributed, collaborative work environments, such as military network-enabled operations.
Heart transplantation has been carried out in 340 patients in Ottawa, including seventy-one who required mechanical circulatory support as a bridge to transplant. Survival in Ottawa was compared with other Canadian centers based on data from the Canadian Organ Replacement Register up to the year 2000 and with the International Society of Heart and Lung Transplantation (ISHLT) registry 2001. For survival analysis, the number of adult patients at risk at year 0 was 303 (87 transplanted from 1985 to 1990, 105 from 1990 to 1994, and 111 from 1995 to 2000). The Statistical Analysis System (SAS) life test procedure was used. Survival was not adjusted for comorbidities or heart failure class. For the year of transplant 1985-1989, one-, five-, and ten-year patient survival in Ottawa was 83%, 70%, and 60%, respectively, compared to 82%, 71%, and 54%, respectively, for Canada (Wilcoxon test, P = 0.71), and compared to one- and five-year survival for ISHLT from 1980 to 1987 at 76% and 60%, respectively. For 1990-1994, one-, five-, and ten-year patient survival in Ottawa was 88%, 81%, and 74%, respectively, compared to 80%, 71%, and 61%, respectively, for Canada (P = 0.05), and compared to one- and five-year survival for ISHLT from 1998 to 1992 at 80% and 68%, respectively. For 1995-2000, one- and five-year patient survival in Ottawa was 90% and 82%, respectively, compared to 85% and 76%, respectively, for Canada (P = 0.09), and compared to one- and five-year survival for ISHLT from 1993 to 1996 at 82% and 68%, respectively. Survival after heart transplantation in Ottawa compares favorably with Canadian and international data.
Climate change is altering environmental temperature, a factor that influences ectothermic organisms by controlling rates of physiological processes. Demographic effects of warming, however, are determined by the expression of these physiological effects through predator-prey and other species interactions. Using field observations and controlled experiments, we measured how increasing temperatures in the Arctic affected development rates and mortality rates (from predation) of immature Arctic mosquitoes in western Greenland. We then developed and parametrized a demographic model to evaluate how temperature affects survival of mosquitoes from the immature to the adult stage. Our studies showed that warming increased development rate of immature mosquitoes (Q10 = 2.8) but also increased daily mortality from increased predation rates by a dytiscid beetle (Q10 = 1.2-1.5). Despite increased daily mortality, the model indicated that faster development and fewer days exposed to predators resulted in an increased probability of mosquito survival to the adult stage. Warming also advanced mosquito phenology, bringing mosquitoes into phenological synchrony with caribou. Increases in biting pests will have negative consequences for caribou and their role as a subsistence resource for local communities. Generalizable frameworks that account for multiple effects of temperature are needed to understand how climate change impacts coupled human-natural systems.
Rapid warming is predicted to increase insect herbivory across the tundra biome, yet how this will impact the community and ecosystem dynamics remains poorly understood. Increasing background invertebrate herbivory could impede Arctic greening, by serving as a top-down control on tundra vegetation. Many tundra ecosystems are also susceptible to severe insect herbivory outbreaks which can have lasting effects on vegetation communities. To explore how tundra-insect herbivore systems respond to warming, we measured shrub traits and foliar herbivory damage at 16 sites along a landscape gradient in western Greenland. Here we show that shrub foliar insect herbivory damage on two dominant deciduous shrubs, Salix glauca and Betula nana, was positively correlated with increasing temperatures throughout the first half of the 2017 growing season. We found that the majority of insect herbivory damage occurred in July, which was outside the period of rapid leaf expansion that occurred throughout most of June. Defoliators caused the most foliar damage in both shrub species. Additionally, insect herbivores removed a larger proportion of B. nana leaf biomass in warmer sites, which is due to a combination of increased foliar herbivory with a coinciding decline in foliar biomass. These results suggest that the effects of rising temperatures on both insect herbivores and host species are important to consider when predicting the trajectory of Arctic tundra shrub expansion.
Mechanical circulatory support devices may be used for patients with end-stage heart failure for bridging either to cardiac transplant or to recovery of the native heart. While less common in adolescents, fulminant heart failure may be rapidly fatal in these patients unless circulatory support can be instituted.
To assess the outcomes and the utility of mechanical circulatory assist devices for children.
A retrospective review of pediatric patients (18 years of age or younger) who underwent circulatory support at the Ottawa Heart Institute, Ottawa, Ontario, from 1992 to 2001 was performed using chart audits.
Seven patients (four boys, three girls) with a mean age of 14.9 +/- 0.9 years were supported with Thoratec ventricular assist devices (n=6) or a CardioWest total artificial heart (n=1). Preoperatively, the cardiac index was 1.64 +/- 0.2 L/min/m2 on one or two inotropes with ejection fractions of 11 +/- 2.2%. Mean duration of circulatory support was 59.3 +/- 17.2 days with a hospital length of stay of 89.6 +/- 12.8 days. All seven patients underwent successful transplantation and were discharged home.
Pediatric patients with fulminant heart failure may be bridged to cardiac transplant successfully with mechanical circulatory support devices.
This study was an extension into an operational setting of previous laboratory work investigating the use of zopiclone and melatonin to facilitate early circadian sleep in transport aircrew. The previous laboratory-based study demonstrated that both melatonin and zopiclone were effective in inducing early circadian sleep without impacting on psychomotor performance after a 7-h sleep period.
In a repeated measures, placebo-controlled protocol, 30 aircrew flew 3 transatlantic missions over which they took each of the 3 medications (placebo, sustained-release melatonin 2 mg, or zopiclone 5 mg) at an early body clock time (17:00) during their first stopover. They wore wrist actigraphs prior to and throughout the missions, took a single dose of their scheduled medication immediately prior to their early circadian bedtime, and completed a sleep questionnaire on arising from their medicated sleep.
The results of the actigraphic data show that relative to placebo, aircrew on melatonin and zopiclone fell asleep more quickly (melatonin: p
The prognostic factors that determine outcome in patients with necrotizing fasciitis remain poorly understood. The aim of this study was to analyze the variables that affect the mortality and morbidity of patients with necrotizing fasciitis and to create a simple method for estimating the probability of mortality.
The authors undertook a retrospective review of all patients with necrotizing fasciitis treated in three tertiary care hospitals in Ontario, Canada, between January of 1994 and June of 2001. Demographic, comorbid illness, and disease-specific data were collated and analyzed for associations with outcome. Using logistic regression analysis, probability estimates for the prediction of mortality were developed, based on three contributing independent factors.
Ninety-nine patients satisfied the inclusion criteria. Overall mortality was 20 percent. Sixteen patients suffered from amputation or organ loss. The most common comorbidities were diabetes (30 percent), immunocompromised status (17 percent), and chickenpox (11 percent). Advanced age (odds ratio, 1.04; 95 percent confidence interval, 1.01 to 1.08; p = 0.012), streptococcal toxic shock syndrome (odds ratio, 10.54; 95 percent confidence interval, 2.80 to 39.44; p
Bioaerosols are an important component of the total atmospheric aerosol load, with implications for human health, climate feedbacks and the distribution and dispersal of microbial taxa. Bioaerosols are sourced from marine, freshwater and terrestrial surfaces, with different mechanisms potentially responsible for releasing biological particles from these substrates. Little is known about the production of freshwater and terrestrial bioaerosols in polar regions. We used portable collection devices to test for the presence of picocyanobacterial aerosols above freshwater and soil substrates in the southwestern Greenland tundra and the McMurdo Dry Valleys of Antarctica. We show that picocyanobacterial cells are present in the near-surface air at concentrations ranging from 2,431 to 28,355 cells m-3 of air, with no significant differences among substrates or between polar regions. Our concentrations are lower than those measured using the same methods in temperate ecosystems. We suggest that aerosolization is an important process linking terrestrial and aquatic ecosystems in these polar environments, and that future work is needed to explore aerosolization mechanisms and taxon-specific aerosolization rates. Our study is a first step toward understanding the production of bioaerosols in extreme environments dominated by microbial life.