Movement responses to environment: fast inference of variation among southern elephant seals with a mixed effects model.

Like many species, movement patterns of southern elephant seals (Mirounga leonina) are being influenced by long-term environmental change. These seals migrate up to 4,000 km from their breeding colonies, foraging for months in a variety of Southern Ocean habitats. Understanding how movement patterns vary with environmental features and how these relationships differ among individuals employing different foraging strategies can provide insight into foraging performance at a population level. We apply new fast-estimation tools to fit mixed effects within a random walk movement model, rapidly inferring among-individual variability in southern elephant seal environment-movement relationships. We found that seals making foraging trips to the sea ice on or near the Antarctic continental shelf consistently reduced speed and directionality (move persistence) with increasing sea-ice coverage but had variable responses to chlorophyll a concentration, whereas seals foraging in the open ocean reduced move persistence in regions where circumpolar deep water shoaled. Given future climate scenarios, open-ocean foragers may encounter more productive habitat but sea-ice foragers may see reduced habitat availability. Our approach is scalable to large telemetry data sets and allows flexible combinations of mixed effects to be evaluated via model selection, thereby illuminating the ecological context of animal movements that underlie habitat usage.

Improved exercise tolerance after propranolol, diltiazem or nifedipine in angina pectoris: comparison at 1, 3 and 8 hours and correlation with plasma drug concentration.

Exercise tolerance 1, 3 and 8 hours after 80 mg of propranolol, 120 mg of diltiazem and 20 mg of nifedipine, and after 20 minutes of 0.6 mg of sublingual nitroglycerin were compared with placebo in 15 men who had chronic stable angina pectoris. Three hours after drug ingestion, the exercise time was prolonged by 72 +/- 26, 162 +/- 27 and 161 +/- 30 seconds (p less than 0.05) for propranolol, diltiazem and nifedipine, respectively, and by 123 +/- 35 seconds (p less than 0.001) 20 minutes after sublingual nitroglycerin compared with placebo. The onset of ST-segment depression greater than or equal to 0.1 mV was delayed by 120 +/- 34, 203 +/- 29 and 189 +/- 35 seconds (p less than 0.05) and by 79 +/- 23 seconds (p less than 0.05), respectively. After propranolol, the peak rate-pressure product decreased compared with placebo (15.1 +/- 1.1 U [10(-3)] vs 20.0 +/- 1.5 U, p less than 0.01). In contrast, the peak rate-pressure product was greater after diltiazem and nifedipine than after placebo (22.2 +/- 1.3 U [p less than 0.05] and 23.8 +/- 1.4 U [p less than 0.01]). The maximal increase in exercise tolerance was most marked for each drug at 3 hours, but was also significant at 1 hour for nifedipine and at 8 hours for diltiazem. At 3 hours, an increase in exercise time of more than 2 minutes was observed in 4 of 6 patients who had plasma propranolol concentrations greater than 40 ng/ml, 8 of 9 who had a plasma diltiazem concentration greater than 150 ng/ml, and in 7 of 7 who had a plasma nifedipine concentration greater than 90 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors influencing the long-term prognosis of treated patients with variant angina.

To determine the prognosis of variant angina and the factors influencing it, 169 consecutive patients hospitalized in our coronary unit were followed for a mean of 15.3 months (range 1 to 68). Survival at 1, 2, and 3 years was 95%, 90%, and 87%, respectively; survival without myocardial infarction was 80%, 78%, and 75%. Twenty of the 22 myocardial infarctions and eight of the 14 deaths occurred within the first 3 months. Mantel-Haenszel log-rank analysis demonstrated that coronary disease, ventricular function, and the degree of disease activity were significant interdependent variables that influenced both survival and survival without infarction. At 1, 2, and 3 years, survival for patients with multivessel disease was 81%, 76%, and 66%; for patients with one-vessel disease, 97%, 92%, and 92%; and for patients without stenoses greater than or equal to 70%, 98% at each year (p = .0003). Survival without infarction at 1 year was 88% in patients with no stenoses greater than or equal to 70% and 82% in patients with single-vessel disease; it did not change thereafter in either group, but was 62%, 58%, and 50% at 1, 2, and 3 years in patients with multivessel disease (p = .001). Treatment did not influence survival in any subgroup (only 14 patients died overall) or survival without infarction in patients with multivessel disease. However, in patients without multivessel disease, treatment with nifedipine, diltiazem, and verapamil improved survival without infarction compared to treatment with perhexiline maleate or long-acting nitrates alone (92% vs 67% at 1, 2, and 3 years; p less than .005). Thus in addition to preventing angina, nifedipine, diltiazem, and verapamil appear to reduce complications in patients with variant angina without multivessel disease.