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Biomedical subjects

W Ullrich

Publications and source records attributed to W Ullrich.

33 records · Page 2Linked to original sources
PubMed1990

Effects of solar radiation on photoorientation, motility and pigmentation in a freshwater Peridinium.

Solar radiation has a pronounced effect on photoorientation, motility and pigmentation in the freshwater dinoflagellate, Peridinium gatunense. Photoorientation (positive phototaxis) is impaired even after short exposure times and is totally inhibited after about 2.5 h. The percentage of motile cells decreases after short exposure times and after 4 h most cells are immotile. Likewise, the mean velocity decreases after an initial light-induced increase (photokinesis) under solar radiation. Solar UV-B (280-320 nm) radiation seems to be the major cause for the effects, since cutting off shorter wavelength by an ozone cuvette or WG filters prolongs the tolerated exposure times. Possible UV-B targets are the photoreceptor pigments since solar radiation causes a massive bleaching of the cells within a few hours.

Animals↗
PubMed1990

Photoorientation, motility and pigmentation in a freshwater peridinium affected by ultraviolet radiation.

The effects of ultraviolet radiation on orientation, motility and pigmentation were measured in the freshwater dinoflagellate, Peridinium gatunense. Histograms of the positive phototactically oriented cells showed a decrease in the degree of orientation even after short exposure times. Quantification of the orientation revealed a significant inhibition after 2 h exposure. Similarly, the percentages of motile cells and the mean linear velocity of the cells was strongly affected. UV radiation also caused a massive bleaching of the cellular pigments as shown by absorption spectra determined after increasing exposure times. The ecological consequences of these effects are discussed.

Animals↗
PubMed1990

[Procurement of organ donors--initial results of the Berlin-Potsdam-Frankfurt model].

The shortage of donor kidneys is the main cause of the even insufficient supply of patients suffering from end stage renal disease. In 1987 a transplant coordinator to the districts Berlin, Frankfurt and Potsdam with 3.1 Mio inhabitants was introduced. The functions of the coordinator and the approach to organ procurement are described in detail. In comparison with 1986 the number of explanted kidneys could doubled in 1988 (68 vs 143). The number of 46.3 explanted kidneys per million inhabitants is comparable with other areas or countries with excellent organ procurement system.

Berlin↗
PubMed1989

[New non-invasive possibilities for assessing the function of the utero- and fetoplacental unit: Doppler sonography flow characteristics of selected arteries in normal pregnancy].

The introduction of the Doppler ultrasound measurements opened a new functional dimension in ultrasound diagnosis. For the first time, there is a possibility of estimating both the physiology and the pathophysiology of the uteroplacentofoetal haemodynamics with a noninvasive method during pregnancy. On the basis of more than 400 Doppler ultrasound vascular tests in uteroplacental arteries and in the umbilical artery of 110 pregnant women the blood flow velocity wave-forms were analyzed qualitatively with the pulsatility index, the resistance index and the S/D ratio. The gestational age-related decrease of these values in normal pregnancies reflects a reduction of the flow resistance in placental villous circulation. The values in retroplacentary arteries depend on the location of the tested vessel. The reference values are presented and the problems of the Doppler ultrasound numerical value inquiry and interpretation are discussed.

Arteries↗