No abstract

We examined photosynthetic characteristics of 21 tree species from a Panamanian forest differing in successional status. We hypothesized that functional guilds of species, grouped by successional status, would differ in photosynthetic performance and that pioneers would be more sensitive to seasonality and more variable in response to light than intermediate or shade tolerants. Steady-state leaf-level photosynthesis (A) was measured in situ on eight trees per species. Light response curves were generated by fitting a hyperbolic model to these data. Average light saturated photosynthetic rates (Amax) were then calculated for each species. Variability of light, photosynthesis, and leaf characteristics were quantified using coefficients of variation (CV). Significant differences were detected among species and functional groups for A, Amax, and leaf N concentration. Functional group explained 46% of the observed variation in A. Pioneers exhibited higher light-saturated photosynthetic rates than intermediates; both were higher than shade tolerants. Intermediates were the most seasonally plastic group and had the highest leaf N concentration. Shade tolerants were found in lower, more variable light environments than pioneers. A strong positive correlation between diameter growth rate and photosynthetic rate (r2 = 0.55, p = 0.004) was observed across species. Our results tend to confirm the hypothesis that physiological traits can be used to differentiate among functional groups of plants. However, no evidence was found for higher plasticity of pioneer compared with shade-tolerant species.Key words: tropical trees, physiological plasticity, photosynthesis, nitrogen, growth, tropical succession.

Computed tomographic angiography was found to be useful in the pre-operative planning of virtually all patients undergoing repair of congenital cardiac malformations, regardless of diagnosis. Specifically, the studies were essential in select populations, such aortic arch or pulmonary vein repairs, and helped to determine cannulation sites for repeat operations while significantly reducing the need for invasive imaging.

Objective To study the effects of duration of preoperative prostaglandin E1 (PGE) exposure on perioperative outcomes of the arterial switch operation in patients with transposition of the great arteries with an intact ventricular septum (TGA-IVS). Design Retrospective chart review Setting Pediatric cardiac intensive care unit in a tertiary care children’s hospital. Patients All patients with TGA-IVS from 1995 to 2008 Outcome Measures Inotropic score was calculated for all patients in the first 5 postoperative days and maximum inotropic score was recorded. Length of postoperative mechanical ventilation, fluid balance, mechanical ventilation time, as well as ICU and hospital stay were recorded for all patients. Results Study population included 59 patients, 41(69%) underwent balloon atrial septostomy. PGE was used in 52 patients, median exposure of 59 hours, range 0 to 272 hours. Longer preoperative PGE exposure was associated with longer preoperative mechanical ventilation (p<.001). There was no association between preoperative PGE duration and cardiopulmonary bypass time, cross-clamp time, or total hospital stay. Patients with longer preoperative PGE exposure had a lower postoperative inotrope score (10 v. 15 p=.02). Conclusion Greater preoperative PGE exposure was associated with prolonged preoperative mechanical ventilation. Longer PGE exposure was associated wtih lower postoperative inotrope requirements. Aggressive efforts to avoid or shorten PGE infusion duration may not be warranted in this population.