Plant community re-organization and increased productivity due to multi-year nutrient enrichment of a coastal grassland.

Nutrient enrichment alters plant community structure and function at a global scale. Coastal plant systems are expected to experience increased rates of nitrogen and phosphorus deposition by 2100, caused mostly by anthropogenic activity. Despite high density of studies investigating connections between plant community structure and ecosystem function in response to nutrient addition, inconsistencies in system response based on the ecosystem in question calls for more detailed analyses of nutrient impacts on community organization and resulting productivity response. Here, we focus on nutrient addition impacts on community structure and organization as well as productivity of different lifeforms in a coastal grassland. We established long-term nutrient enrichment plots in 2015 consisting of control (C), nitrogen (N), phosphorus (P), and nitrogen + phosphorus (NP) treatments. In 2017 we collected graminoid and forb productivity, root productivity, and community composition for each plot. We found no N x P interaction, but N enrichment was a significant main effect on productivity, highlighting N limitation in coastal systems. Importantly, nutrient enrichment treatments did not alter root productivity. However, all treatments caused significant differences in community composition. Using rank abundance curves, we determined that community composition differences were driven by increased dominance of nitrophilous graminoids, re-organization of subordinate species, and species absences in N and NP plots. Results of this study highlight how coastal grassland communities are impacted by nutrient enrichment. We show that community re-organization, increased dominance, and absence of critical species are all important mechanisms that reflect community-level impacts of nutrient enrichment in our coastal grassland site.

Literature-based latitudinal distribution and possible range shifts of two US east coast dune grass species (Uniola paniculata and Ammophila breviligulata).

Previous work on the US Atlantic coast has generally shown that coastal foredunes are dominated by two dune grass species, Ammophila breviligulata (American beachgrass) and Uniola paniculata (sea oats). From Virginia northward, A. breviligulata dominates, while U. paniculata is the dominant grass south of Virginia. Previous work suggests that these grasses influence the shape of coastal foredunes in species-specific ways, and that they respond differently to environmental stressors; thus, it is important to know which species dominates a given dune system. The range boundaries of these two species remains unclear given the lack of comprehensive surveys. In an attempt to determine these boundaries, we conducted a literature survey of 98 studies that either stated the range limits and/or included field-based studies/observations of the two grass species. We then produced an interactive map that summarizes the locations of the surveyed papers and books. The literature review suggests that the current southern range limit for A. breviligulata is Cape Fear, NC, and the northern range limit for U. paniculata is Assateague Island, on the Maryland and Virginia border. Our data suggest a northward expansion of U. paniculata, possibly associated with warming trends observed near the northern range limit in Painter, VA. In contrast, the data regarding a range shift for A. breviligulata remain inconclusive. We also compare our literature-based map with geolocated records from the Global Biodiversity Information Facility and iNaturalist research grade crowd-sourced observations. We intend for our literature-based map to aid coastal researchers who are interested in the dynamics of these two species and the potential for their ranges to shift as a result of climate change.

Use of myocardial deformation imaging to detect preclinical myocardial dysfunction before conventional measures in patients undergoing breast cancer treatment with trastuzumab.

BACKGROUND: Trastuzumab prolongs survival in patients with human epidermal growth factor receptor type 2-positive breast cancer. Sequential left ventricular (LV) ejection fraction (EF) assessment has been mandated to detect myocardial dysfunction because of the risk of heart failure with this treatment. Myocardial deformation imaging is a sensitive means of detecting LV dysfunction, but this technique has not been evaluated in patients treated with trastuzumab. The aim of this study was to investigate whether changes in tissue deformation, assessed by myocardial strain and strain rate (SR), are able to identify LV dysfunction earlier than conventional echocardiographic measures in patients treated with trastuzumab. METHODS: Sequential echocardiograms (n = 152) were performed in 35 female patients (51 +/- 8 years) undergoing trastuzumab therapy for human epidermal growth factor receptor type 2-positive breast cancer. Left ventricular EF was measured by 2- and 3-dimensional (2D and 3D) echocardiography, and myocardial deformation was assessed using tissue Doppler imaging and 2D-based (speckle-tracking) strain and SR. Change over time was compared every 3 months between baseline and 12 months. RESULTS: There was no overall change in 3D-EF, 2D-EF, myocardial E-velocity, or strain. However, there were significant reductions seen in tissue Doppler imaging SR (P < .05), 2D-SR (P < .001), and 2D radial SR (P < .001). A drop > or =1 SD in 2D longitudinal SR was seen in 18 (51%) patients; 13 (37%) had a similar drop in radial SR. Of the 18 patients with reduced longitudinal SR, 3 had a concurrent reduction in EF > or =10%, and another 2 showed a reduction over 20 months follow-up. CONCLUSIONS: Myocardial deformation identifies preclinical myocardial dysfunction earlier than conventional measures in women undergoing treatment with trastuzumab for breast cancer.

Association of myocardial strain with left ventricular geometry and progression of hypertensive heart disease.

Different patterns of abnormal left ventricular (LV) geometry are associated with variations in prognosis, but the mechanisms of these effects remain undefined. We investigated the association of myocardial deformation with these findings and their evolution. Two-dimensional echocardiography was performed in 85 hypertensive patients referred for serial evaluation (age 58 +/- 13 years, 48% male). LV mass index and regional wall thickness were used to assign patients into groups with normal geometry, concentric remodeling, concentric hypertrophy, and eccentric hypertrophy. Septal strain and strain rate were measured using velocity vector imaging. The evolution of morphological changes was followed over 2.7 +/- 1.3 years. Analysis of LV geometry revealed normal geometry in 13 patients (15%), concentric remodeling in 20 (24%), concentric hypertrophy in 42 (49%), and eccentric hypertrophy in 10 (12%). Overall strain was -13.6 +/- 4.5%, and strain rate was -0.65 +/- 0.24/second. Strain was significantly lower in patients with concentric remodeling (-12.8 +/- 4.2%) or concentric hypertrophy (-12.5 +/- 4.1%) compared with patients with normal geometry (-17.5 +/- 5.5%, p < or =0.05), and these associations were independent of blood pressure. Strain rate was also significantly reduced in patients with concentric hypertrophy (p < or =0.01). There were no significant differences in baseline strain, wall stress, blood pressure, or age between patients who changed LV geometric class and those who did not. In conclusion, baseline myocardial tissue deformation, but not evolution, is associated with LV geometry in treated hypertensive patients.

Performance of conventional echocardiographic parameters and myocardial measurements in the sequential evaluation of left ventricular function.

Echocardiography is frequently used for sequential evaluation of left ventricular (LV) function, although the reproducibility of such conventional measurements as LV ejection fraction (EF) have been questioned. The utility of such newer measurements as tissue Doppler imaging and left atrial (LA) size in serial clinical testing are undefined. The magnitude and clinical relevance of changes in conventional and new measurements of LV function were investigated and compared in 346 consecutive patients undergoing sequential echocardiography. Change in LA area, LVEF, tissue E velocity (Em), and transmitral E to Em ratio (E/Em) were compared over 304 +/- 239 days. Changes within and between parameters (after mean correction to make measurements comparable) were assessed in groups designated as stable (n = 144) or unstable (n = 202) according to clinical progress. A single observer remeasured these parameters in stable patients individually and with paired studies side by side. Significant variability was seen in all measurements, with change in LVEF the only parameter differing between stable and unstable groups (6.4 +/- 8.9% vs 9.4 +/- 5.4%; p <0.001). Tissue Em and E/Em ratio were more variable than LA area or LVEF. In stable patients, LVEF changed the least and E/Em changed the most over time (p <0.05). With a single blinded observer, Em had improved reproducibility (1.5 +/- 1.9 vs 2.3 +/- 2.6 cm/s; p <0.001), as did visual EF. In conclusion, variability in all measurements was high irrespective of clinical status. Newer measurements were no better than LVEF in detecting changes in clinical status. Sequential LV assessment should be interpreted with caution, and more robust measurements are needed.