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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 74 (1987), S. 396-403 
    ISSN: 1432-1939
    Keywords: Benthos ; Drift ; Experiments ; Predators ; Stream
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We carried out an experimental field study in a Swedish stream in order to determine whether mobile predators enhance the drift of stream insects. We increased the density of nymphs of the predaceous perlid stonefly, Dinocras cephalotes, in an experimental section of a stream up to densities in another more densely populated part of the same stream. The drift of several benthic species increased significantly compared to a control section where D. cephalotes were rare. Experiments carried out in September showed a strongly elevated drift response in nymphs of the mayfly Baetis rhodani only, whereas May experiments resulted in increased drift in B. rhodani as well as the amphipod Gammarus pulex, the stonefly Leuctra fusca, chironomids, and the total number of drifting animals. In September, we found that the drift response of Baetis rhodani to predator disturbance was dependent on the size of mayfly nymphs; small nymphs appeared in greater numbers in the drift nets than did large nymphs. A subsequent laboratory analysis of drift lengths of B. rhodani nymphs supported the hypothesis that small nymphs travel in the drift for longer than do large nymphs, particularly in darkness. We suggest that morphological constraints in vision or swimming performance, or both, cause small nymphs to drift longer. In May, size-dependent drift was less obvious, probably because the size of the nymphs was considerably greater than in September.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7241
    Keywords: felodipine ; hypertension ; impaired renal function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-three patients with severe hypertension and impaired renal function were included in an open study of the efficacy and tolerance of felodipine treatment over 6 months. All patients were previously treated with a diuretic, a beta blocker, and a vasodilator, and eight of them also received an ACE inhibitor. At the start of felodipine treatment the previously used vasodilator was withdawn. In nine patients the concomitant antihypertensive treatment was reduced during the study. The glomerular filtration rate (GFR), as51Cr EDTA clearance, was determined before and at the end of the study. The blood pressure (BP) and heart rate (HR) were recorded at all clinical visits in the moring 12 hours after the evening dose of felodipine and 2 hours after the morning dose. Plasma concentrations of felodipine were measured at every visit before the morning dose and 2 hours after dose. The BP was reduced after felodipine was substituted for the previously used vasodilator. A significant additional antihypertensive effect was recorded 2 hours after the dose and amounted to −37±22/−15±12 mmHg (p=0.0001/p=0.0002) at 6 months. The effect measured 12 hours after the dose was less pronounced and was −11±28/−6±10 mmHg (p=0.15/p=0.03). Mean GFR was unchanged during the study, 38±19 versus 38±19 ml/min (n=16). There was a sixfold interindividual variation in the trough plasma concentrations at steady state at the same drug dosage. Higher plasma concentrations seemed to be required to achieve the same antihypertensive effects as in patients with less severe hypertension and normal renal function. The frequency of adverse effects and the number of patients withdrawn (n=5) were somewhat higher than reported in patients with normal renal function and may be related to the high doses (up to 80 mg daily) used. In conclusion our data suggest that felodipine, in addition to other antihypertensives, is effective and is usually well tolerated in the treatment of patients with severe hypertension and reduced renal function. In order to ensure a more even reduction of BP over the day, a tid dosage regimen of the plain-tablet formulation used in this study may be preferable.
    Type of Medium: Electronic Resource
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