Dinoflagellates of multicorer surface sediments

Only very few studies focus on recent calcareous dinoflagellate cyst diversity, geographic distribution and ecology, so that information on the distribution patterns and environmental affinities of individual cyst species is extremely limited. This information is, however, essential if we want to use calcareous dinoflagellate cysts for palaeoenvironmental reconstruction. Surface sediment samples from the generally oligotrophic western equatorial Atlantic Ocean, offshore northeast Brazil, were therefore quantitatively analysed for their calcareous dinoflagellate cyst content, including the calcareous vegetative coccoid Thoracosphaera heimii. Seven calcareous dinoflagellate cyst species/morphotypes and T. heimii were encountered in high concentrations throughout the area. Substantial differences in the distribution patterns were observed. The highest concentrations of cysts are found in sediments of the more oligotrophic, oceanic regions, beyond the influence of Amazon River discharge waters. Dinoflagellates producing calcareous cysts thus appear to be capable of surviving low nutrient concentrations and produce large numbers of cysts in relatively stable and predictable environments affected by minimal seasonality. To test for the environmental affinities of individual species, distribution patterns in surface sediments were compared with temperature, salinity, density and stratification gradients within the upper water column (0-100 m) over different times of the year, using principal components analysis and redundancy analysis. T. heimii and four of the seven encountered cyst species (Sphaerodinella? albatrosiana, two morphotypes of Sphaerodinella? tuberosa and Scrippsiella regalis) relate to these parameters significantly and the variations in the cyst associations appear to be associated with the different surface water currents characterising the area. The results imply that calcareous dinoflagellate cyst distributions can potentially be used to distinguish between different open oceanic environments and they could, therefore, be useful in tracing water mass movements throughout the late Quaternary.

(Appendix A) Abundance of calcareous dinoflagellates of sediment core GeoB2204-2

The environmental preferences of calcareous dinoflagellates have been investigated over the last 140 ka by comparing material from two sediment cores: one from the highly productive equatorial divergence of the eastern Atlantic Ocean and the other from the low productivity western tropical Atlantic Ocean. Pronounced differences in palaeoproductivity between the two sediment cores are indicated by high and variable organic carbon accumulation rates in the east, in contrast to relatively constant and low values in the west. Calcareous dinoflagellates show just the opposite pattern: high accumulation rates in the west and lower in the east. At the equatorial divergence, temporal variations of calcareous dinoflagellate and organic carbon accumulation rates show, for the most part, an inverse relationship. High calcareous dinoflagellate content coincides with low organic carbon accumulation rates and vice versa. In the investigated region and time interval, enhanced production of calcareous dinoflagellates can be correlated to periods of reduced palaeoproductivity probably related to relatively stratified conditions of the upper water column.

Natriuretic peptide-based screening and collaborative care for heart failure:the STOP-HF randomized trial

IMPORTANCE: Prevention strategies for heart failure are needed.

OBJECTIVE: To determine the efficacy of a screening program using brain-type natriuretic peptide (BNP) and collaborative care in an at-risk population in reducing newly diagnosed heart failure and prevalence of significant left ventricular (LV) systolic and/or diastolic dysfunction.

DESIGN, SETTING, AND PARTICIPANTS: The St Vincent's Screening to Prevent Heart Failure Study, a parallel-group randomized trial involving 1374 participants with cardiovascular risk factors (mean age, 64.8 [SD, 10.2] years) recruited from 39 primary care practices in Ireland between January 2005 and December 2009 and followed up until December 2011 (mean follow-up, 4.2 [SD, 1.2] years).

INTERVENTION: Patients were randomly assigned to receive usual primary care (control condition; n=677) or screening with BNP testing (n=697). Intervention-group participants with BNP levels of 50 pg/mL or higher underwent echocardiography and collaborative care between their primary care physician and specialist cardiovascular service.

MAIN OUTCOMES AND MEASURES: The primary end point was prevalence of asymptomatic LV dysfunction with or without newly diagnosed heart failure. Secondary end points included emergency hospitalization for arrhythmia, transient ischemic attack, stroke, myocardial infarction, peripheral or pulmonary thrombosis/embolus, or heart failure.

RESULTS: A total of 263 patients (41.6%) in the intervention group had at least 1 BNP reading of 50 pg/mL or higher. The intervention group underwent more cardiovascular investigations (control, 496 per 1000 patient-years vs intervention, 850 per 1000 patient-years; incidence rate ratio, 1.71; 95% CI, 1.61-1.83; P<.001) and received more renin-angiotensin-aldosterone system-based therapy at follow-up (control, 49.6%; intervention, 56.5%; P=.01). The primary end point of LV dysfunction with or without heart failure was met in 59 (8.7%) of 677 in the control group and 37 (5.3%) of 697 in the intervention group (odds ratio [OR], 0.55; 95% CI, 0.37-0.82; P = .003). Asymptomatic LV dysfunction was found in 45 (6.6%) of 677 control-group patients and 30 (4.3%) of 697 intervention-group patients (OR, 0.57; 95% CI, 0.37-0.88; P = .01). Heart failure occurred in 14 (2.1%) of 677 control-group patients and 7 (1.0%) of 697 intervention-group patients (OR, 0.48; 95% CI, 0.20-1.20; P = .12). The incidence rates of emergency hospitalization for major cardiovascular events were 40.4 per 1000 patient-years in the control group vs 22.3 per 1000 patient-years in the intervention group (incidence rate ratio, 0.60; 95% CI, 0.45-0.81; P = .002).

CONCLUSION AND RELEVANCE: Among patients at risk of heart failure, BNP-based screening and collaborative care reduced the combined rates of LV systolic dysfunction, diastolic dysfunction, and heart failure.

TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00921960.