Preparing the Landscape for Invasion: Accelerating the Evolution of Resistance

Restoration of forests devastated by nonnative invaders often dominates the attention of forest mangers and their actions. However, taking a broader view of the invasion beyond the crisis areas reveals opportunities where proactive management can alter the outcome of the invasion in threatened areas. Proactive management moves past the idea of protecting the hosts from exposure to the established non-native invader and shifts toward facilitating naturalization by preparing the landscape to sustain critical ecosystem function into the future in the presence of the invader. Increasing the frequencies of durable resistance or tolerance traits within tree populations is accepted as a promising avenue for the co-existence of native tree species and non-native pathogens. Therefore the objective of proactive intervention is use silviculture to position the ecosystem to facilitate the evolution of pathogen-resistance in the tree populations upon invasion (Schoettle and Sniezko 2007*). Diversifying the age class structure by stimulating regeneration in the healthy forest will provide a larger population size for resistance selection upon invasion and simultaneous selection in both the younger and older cohorts. Accelerating the generation time and natural selection process through silvicultural treatments will reduce the ecological consequences of mortality in any one cohort and increases the potential for development of durable resistance within the population while maintaining broad genetic diversity. Introduction of stock with heritable resistance into stands that are not yet invaded by the nonnative pathogen would also increase the frequency of resistance on the landscape and accelerate the evolution of resistance. In addition, proactive artificial regeneration will reduce the window of time, after invasion, when the stands regeneration capability is comprise by mortality of the mature trees (Schoettle and Sniezko 2007*). This poster will discuss proactive silvicultural options for managing (1) high elevation 5-needle pines threatened by Cronartium ribicola (white pine blister rust) and (2) Port-Orford-cedar stands at risk for impacts from Phytophthora lateralis. [*Schoettle, AW and RA Sniezko (2007) Proactive intervention to sustain high elevation pine ecosystems threatened by white pine blister rust. Journal of Forest Research 12(5): 327-336. Available at: http://springerlink.metapress.com/content/9v91t44278w74430 /fulltext.pdf

Coronary-artery bypass surgery in patients with left ventricular dysfunction

<p>BACKGROUND The role of coronary-artery bypass grafting (CABG) in the treatment of patients with coronary artery disease and heart failure has not been clearly established.</p> <p>METHODS Between July 2002 and May 2007, a total of 1212 patients with an ejection fraction of 35% or less and coronary artery disease amenable to CABG were randomly assigned to medical therapy alone (602 patients) or medical therapy plus CABG (610 patients). The primary outcome was the rate of death from any cause. Major secondary outcomes included the rates of death from cardiovascular causes and of death from any cause or hospitalization for cardiovascular causes.</p> <p>RESULTS The primary outcome occurred in 244 patients (41%) in the medical-therapy group and 218 (36%) in the CABG group (hazard ratio with CABG, 0.86; 95% confidence interval [CI], 0.72 to 1.04; P=0.12). A total of 201 patients (33%) in the medical-therapy group and 168 (28%) in the CABG group died from an adjudicated cardiovascular cause (hazard ratio with CABG, 0.81; 95% CI, 0.66 to 1.00; P=0.05). Death from any cause or hospitalization for cardiovascular causes occurred in 411 patients (68%) in the medical-therapy group and 351 (58%) in the CABG group (hazard ratio with CABG, 0.74; 95% CI, 0.64 to 0.85; P<0.001). By the end of the follow-up period (median, 56 months), 100 patients in the medical-therapy group (17%) underwent CABG, and 555 patients in the CABG group (91%) underwent CABG.</p> <p>CONCLUSIONS In this randomized trial, there was no significant difference between medical therapy alone and medical therapy plus CABG with respect to the primary end point of death from any cause. Patients assigned to CABG, as compared with those assigned to medical therapy alone, had lower rates of death from cardiovascular causes and of death from any cause or hospitalization for cardiovascular causes.</p&gt

Myocardial viability and survival in ischemic left ventricular dysfunction

BACKGROUND: The assessment of myocardial viability has been used to identify patients with coronary artery disease and left ventricular dysfunction in whom coronary-artery bypass grafting (CABG) will provide a survival benefit. However, the efficacy of this approach is uncertain. METHODS: In a substudy of patients with coronary artery disease and left ventricular dysfunction who were enrolled in a randomized trial of medical therapy with or without CABG, we used single-photon-emission computed tomography (SPECT), dobutamine echocardiography, or both to assess myocardial viability on the basis of prespecified thresholds. RESULTS: Among the 1212 patients enrolled in the randomized trial, 601 underwent assessment of myocardial viability. Of these patients, we randomly assigned 298 to receive medical therapy plus CABG and 303 to receive medical therapy alone. A total of 178 of 487 patients with viable myocardium (37%) and 58 of 114 patients without viable myocardium (51%) died (hazard ratio for death among patients with viable myocardium, 0.64; 95% confidence interval [CI], 0.48 to 0.86; P=0.003). However, after adjustment for other baseline variables, this association with mortality was not significant (P=0.21). There was no significant interaction between viability status and treatment assignment with respect to mortality (P=0.53). CONCLUSIONS: The presence of viable myocardium was associated with a greater likelihood of survival in patients with coronary artery disease and left ventricular dysfunction, but this relationship was not significant after adjustment for other baseline variables. The assessment of myocardial viability did not identify patients with a differential survival benefit from CABG, as compared with medical therapy alone. (Funded by the National Heart, Lung, and Blood Institute; STICH ClinicalTrials.gov number, NCT00023595.)