85 research outputs found
Cold Tolerance of Four Species of Bark Beetle (Coleoptera:Scolytidae) in North America
ABSTRACT We investigated the overwintering biology of four temperate-latitude bark beetles: Dendroctonus frontalis Zimmermann, Ips pini (Say), I. grandicollis (Eichhoff), and I. perroti Swaine. All four species were freeze-susceptible. However, there was variation within and among species in overwintering biology that related to their geographic distribution. D. frontalis and southern populations of I. grandicollis continued to reproduce and develop under the bark of their host plants throughout the winter and did not show any seasonal adjustments in their lower lethal temperatures: mean supercooling point Ϯ SD ϭ Ϫ12.15 Ϯ 4.02 and Ϫ12.25 Ϯ 2.50ЊC. In contrast, northern populations of I. grandicollis and I. pini employ a behavioral strategy in which adults migrate to the forest soil, where they are insulated from temperature extremes by litter and snow. Furthermore, adult supercooling points of both northern populations declined from about Ϫ13ЊC in summer to about Ϫ17ЊC in early winter. A concomitant decline in lipid content suggests that lipid metabolism may be involved in seasonal adjustments of cold tolerance in I. pini. An assortment of temperature manipulations failed to provide any evidence of cold tolerance acclimation. Immatures, which remain in the inner bark of their host trees, have lower lethal temperatures of Ϫ5 to Ϫ12ЊC, and are especially vulnerable to mortality from freezing. I. perroti, a northerly distributed species, had similar cold tolerance and overwinter behavior as northern populations of the other two Ips species. Winter mortality from freezing could be an important determinant of population dynamics in all four species. Understanding variations in cold tolerance and overwinter behavior among insects species may help predict population dynamics and distribution of potential pests
The Fire and Tree Mortality Database, for Empirical Modeling of Individual Tree Mortality After Fire
Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes records from 164,293 individual trees with records of fire injury (crown scorch, bole char, etc.), tree diameter, and either mortality or top-kill up to ten years post-fire. Data span 142 species and 62 genera, from 409 fires occurring from 1981-2016. Additional variables such as insect attack are included when available. The FTM database can be used to evaluate individual fire-caused mortality models for pre-fire planning and post-fire decision support, to develop improved models, and to explore general patterns of individual fire-induced tree death. The database can also be used to identify knowledge gaps that could be addressed in future research
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
Antiplatelet therapy with aspirin, clopidogrel, and dipyridamole versus clopidogrel alone or aspirin and dipyridamole in patients with acute cerebral ischaemia (TARDIS): a randomised, open-label, phase 3 superiority trial
Background: Intensive antiplatelet therapy with three agents might be more effective than guideline treatment for preventing recurrent events in patients with acute cerebral ischaemia. We aimed to compare the safety and efficacy of intensive antiplatelet therapy (combined aspirin, clopidogrel, and dipyridamole) with that of guideline-based antiplatelet therapy.
Methods: We did an international, prospective, randomised, open-label, blinded-endpoint trial in adult participants with ischaemic stroke or transient ischaemic attack (TIA) within 48 h of onset. Participants were assigned in a 1:1 ratio using computer randomisation to receive loading doses and then 30 days of intensive antiplatelet therapy (combined aspirin 75 mg, clopidogrel 75 mg, and dipyridamole 200 mg twice daily) or guideline-based therapy (comprising either clopidogrel alone or combined aspirin and dipyridamole). Randomisation was stratified by country and index event, and minimised with prognostic baseline factors, medication use, time to randomisation, stroke-related factors, and thrombolysis. The ordinal primary outcome was the combined incidence and severity of any recurrent stroke (ischaemic or haemorrhagic; assessed using the modified Rankin Scale) or TIA within 90 days, as assessed by central telephone follow-up with masking to treatment assignment, and analysed by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN47823388.
Findings: 3096 participants (1556 in the intensive antiplatelet therapy group, 1540 in the guideline antiplatelet therapy group) were recruited from 106 hospitals in four countries between April 7, 2009, and March 18, 2016. The trial was stopped early on the recommendation of the data monitoring committee. The incidence and severity of recurrent stroke or TIA did not differ between intensive and guideline therapy (93 [6%] participants vs 105 [7%]; adjusted common odds ratio [cOR] 0·90, 95% CI 0·67–1·20, p=0·47). By contrast, intensive antiplatelet therapy was associated with more, and more severe, bleeding (adjusted cOR 2·54, 95% CI 2·05–3·16, p<0·0001).
Interpretation: Among patients with recent cerebral ischaemia, intensive antiplatelet therapy did not reduce the incidence and severity of recurrent stroke or TIA, but did significantly increase the risk of major bleeding. Triple antiplatelet therapy should not be used in routine clinical practice
International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways.
Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 × 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist
International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways
The motivations for the adoption of management innovation by local governments and its performance effects
This article analyses the economic, political and institutional antecedents and performance effects of the adoption of shared Senior Management Teams (SMTs) – a management innovation (MI) that occurs when a team of senior managers oversees two or more public organizations. Findings from statistical analysis of 201 English local governments and interviews with organizational leaders reveal that shared SMTs are adopted to develop organisational capacity in resource‐challenged, politically risk‐averse governments, and in response to coercive and mimetic institutional pressures. Importantly, sharing SMTs may reduce rather than enhance efficiency and effectiveness due to redundancy costs and the political transaction costs associated with diverting resources away from a high‐performing partner to support their lower‐performing counterpart
Antiplatelet therapy with aspirin, clopidogrel, and dipyridamole versus clopidogrel alone or aspirin and dipyridamole in patients with acute cerebral ischaemia (TARDIS): a randomised, open-label, phase 3 superiority trial
Background: Intensive antiplatelet therapy with three agents might be more effective than guideline treatment for preventing recurrent events in patients with acute cerebral ischaemia. We aimed to compare the safety and efficacy of intensive antiplatelet therapy (combined aspirin, clopidogrel, and dipyridamole) with that of guideline-based antiplatelet therapy.Methods: We did an international, prospective, randomised, open-label, blinded-endpoint trial in adult participants with ischaemic stroke or transient ischaemic attack (TIA) within 48 h of onset. Participants were assigned in a 1:1 ratio using computer randomisation to receive loading doses and then 30 days of intensive antiplatelet therapy (combined aspirin 75 mg, clopidogrel 75 mg, and dipyridamole 200 mg twice daily) or guideline-based therapy (comprising either clopidogrel alone or combined aspirin and dipyridamole). Randomisation was stratified by country and index event, and minimised with prognostic baseline factors, medication use, time to randomisation, stroke-related factors, and thrombolysis. The ordinal primary outcome was the combined incidence and severity of any recurrent stroke (ischaemic or haemorrhagic; assessed using the modified Rankin Scale) or TIA within 90 days, as assessed by central telephone follow-up with masking to treatment assignment, and analysed by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN47823388.Findings: 3096 participants (1556 in the intensive antiplatelet therapy group, 1540 in the guideline antiplatelet therapy group) were recruited from 106 hospitals in four countries between April 7, 2009, and March 18, 2016. The trial was stopped early on the recommendation of the data monitoring committee. The incidence and severity of recurrent stroke or TIA did not differ between intensive and guideline therapy (93 [6%] participants vs 105 [7%]; adjusted common odds ratio [cOR] 0·90, 95% CI 0·67–1·20, p=0·47). By contrast, intensive antiplatelet therapy was associated with more, and more severe, bleeding (adjusted cOR 2·54, 95% CI 2·05–3·16,
The non-occupational environment and the lung:opportunities for intervention
Many environmental factors, both indoors and outdoors, can cause or worsen respiratory disease. Although in many cases individuals have little influence over environmental exposures (e.g., weather conditions), there are many (such as environmental tobacco smoke (ETS) and outdoor air pollution) where interventions can improve health. While for environmental exposures such as air pollution, remediation largely devolves to the government, for exposures such as ETS advice to individuals in these settings will confer benefit. Climate change has begun to feature more and more in the context of health but how this may affect pulmonary disease remains debatable. It is possible that heat associated changes in allergen exposures may be more than counterbalanced by potential reductions in cold related exacerbations of diseases such as COPD. An improved assessment of environmental exposures is key in how we approach the effects of the environment on lung disease which would allow better understanding of gene-environment interactions and how remediation might influence population health for the better
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