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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 129 (1997), S. 71-78 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Behavioural responses to decreasing oxygen concentrations were studied in the amphipods Monoporeia affinis (Lindström) and Pontoporeia femorata Krøyer and the isopod Saduria entomon (L.), all benthic macrofauna species from the Baltic Sea. Infrared time-lapse video recording was used. Seven oxygen concentrations were studied, starting near saturation (about 90%), followed by about 65, 49, 33, 16, 8 and 5% oxygen saturation, with each oxygen level maintained for 24 h. M. affinis was more active than P. femorata. The duration of swimming activity of M. affinis was shorter at ≤33% oxygen saturation compared with at the two highest levels. The duration of swimming by P. femorata was longest at 90, 65 and 5% oxygen saturation. For both amphipods the frequency of swimming activity was highest at 5% oxygen saturation. Above 7% oxygen saturation, S. entomon spent most of its time in the sediment, whereas at levels ≤7% it was most often found on the sediment surface. Both amphipods were predominantly night active (nocturnal), whereas no diurnal variation in behaviour was detected for S. entomon. It is suggested that the amphipods minimise the costs associated with obtaining oxygen as well as their risk of predation by moving little on or above the sediment until a lower critical oxygen level is reached. Below this level, they show an oxygen-seeking behaviour. S. entomon also hid in the sediment for as long as possible, suddenly coming to the surface once the oxygen concentration became intolerably low. Its behaviour is also indicative of a trade-off between predation risk and obtaining sufficient oxygen. It is suggested that the change in behaviour shown at about 33% oxygen saturation could lead to a long-term alteration in community structure in the deeper parts of the northern Baltic proper, whereas the change at about 8% oxygen saturation reflects a more acute, short-term response.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A fast and simple method of determining the mean velocity vector of complex three-dimensional flow fields is outlined. Straight and slanted single hot-wires are rotated in two perpendicular planes. This method increases the angular resolution, which is of importance in flow situations where one of the velocity components dominates and the other changes rapidly from one point to another. The method was calibrated in a wind tunnel and assessed in the internal flow field at the outlet of a fan in a defroster channel. It is shown that the hot-wire method yields good agreement with corresponding flow visualizations determined using a textile thread, and an integration of the measured mean flow yields a flow rate which agrees within a few percent with corresponding direct measurements on an orifice plate.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 15 (1987), S. 141-145 
    ISSN: 1432-1017
    Keywords: Lectins ; diI-C14 ; lateral diffusion ; HT29 cells ; fluorescence photobleaching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The lateral diffusion of lectin-labelled glycoconjugates was studied in the human colon carcinoma cell line HT29 using fluorescence photobleaching techniques. HT29 cells were grown in either Dulbecco's modified Eagle's medium with glucose (25 mM; DMEM-Glu) or with galactose (25 mM; DMEM-Gal). Cell cultivation in the DMEM-Gal medium was assumed to promote a transformation of the cells to become small-intestinal-like with characteristic microvilli and associated enzymes. The diffusion of glycoconjugates labelled with fluoresceinated Triticum vulgaris agglutinin (Wheat germ agglutinin; WGA), Ricinus communis agglutinin-I (RCA-I), Concanavalia ensiformis agglutinin (ConA), Ulex europaeus agglutinin-I (UEA-I) and Arachis hypogaea agglutinin (PNA) was in all cases rapid, with a diffusion constant (D) ranging between 0.4 and 0.8×10-8 cm2 s-1. As a comparison the diffusion of the fluorescent synthetic lipid analog diI-C14 was characterized by D=0.8 − 1.0 × 10−8 cm2 s-1. The diffusion of lectin-labelled surface components could not be related to the presence of microvilli on HT29 cells grown in DMEM-Gal, which ought to yield an apparently lower diffusion rate. The results indicate either that surface glycoconjugates in HT29 cells are dominated by glycolipid, or that the labelled glycoproteins are more or less free to diffuse in the plane of the membrane.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 31 (1987), S. 625-627 
    ISSN: 1432-1041
    Keywords: verapamil ; breast milk ; norverapamil ; breast feeding ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The concentrations of verapamil and norverapamil have been measured in milk and plasma samples from a 32year-old woman treated with verapamil 80 mg tds while breast-feeding her child. The average steady-state concentrations of verapamil and norverapamil in milk were, respectively, 60% and 16% of the concentrations in plasma. The breast-fed child received less than 0.01% of the dose of verapamil given to the mother. No verapamil or norverapamil (〈1 ng/ml) could be detected in the plasma from the child.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 3 (1971), S. 232-235 
    ISSN: 1432-1041
    Keywords: Parkinsonism ; 5-hydroxyindoleacetic acid ; cerebrospinal fluid ; L-DOPA ; homovanillic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 5-Hydroxytryptamine (5-HT) turnover has been studied in eleven patients with Parkinson's disease before and during L-DOPA administration, using a test based on the fact that probenecid inhibits the active transport of acid monoamine metabolites, such as 5-hydroxyindoleacetic acid (5-HIAA), from cerebrospinal fluid to blood. A significant decrease in 5-HT turnover was observed during L-DOPA treatment, and possible mechanisms for it are discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 25 (1983), S. 467-473 
    ISSN: 1432-1041
    Keywords: hydralazine ; heart failure ; pharmacokinetics ; bioavailability ; metabolism ; hypertension ; dapsone ; acetylator phenotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of various disease states, other than hypertension, on the pharmacokinetic behaviour of hydralazine is not completely known. In the present study the pharmacokinetics of oral hydralazine has been evaluated in 7 patients with severe, chronic heart failure, using 8 compensated hypertensives as controls. The pharmacokinetics was evaluated by measuring the plasma concentrations of hydralazine (“apparent” and “real” hydralazine) and hydralazine pyruvate hydrazone, and by assessing acetylator phenotype after a small dose of dapsone. The AUC (area under the plasma concentration curve) following a single, oral 50 mg dose was significantly larger in patients with chronic heart failure NYHA Class III–IV than in patients with essential hypertension without cardiac decompensation. A decreased rate of hepatic elimination of hydralazine is suggested as a major contributory factor to this finding.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1041
    Keywords: disulfiram ; diethylthiocarbamic acid methyl ester ; steady-state ; elimination kinetics ; erythrocyte ALDH activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The elimination kinetics of the methyl esters of diethyldithiocarbamic acid (Me-DDC) and its monothio analogue (Me-DTC) has been compared in ten alcoholic patients after a single oral dose of 400 mg disulfiram (Antabuse). Erythrocyte aldehyde dehydrogenase (ALDH) activity was continuously followed in the subjects until complete inactivation. The relation between individual steady-state concentrations of Me-DTC in plasma, blood acetaldehyde concentration and the dose of disulfiram sufficient to give the disulfiram alcohol reaction was investigated in 12 healthy volunteers treated with increasing doses of disulfiram and then challenged with ethanol. The mean peak plasma concentration of Me-DDC occurred at 1.8 h and its plasma half-life was 6.3 h. The corresponding values for Me-DTC were 3.3 h and 11.2 h, respectively. This suggests oxidative formation of Me-DTC from Me-DDC. In alcoholics with a rapid decrease in erythrocyte ALDH activity (in less than 5 days), the mean peak plasma concentration of Me-DTC was 278 nmol·l−1, whereas the peak concentration was below the detection limit in subjects with a prolonged inactivation time (7–20 days). The healthy volunteers were divided into three groups of four subjects, with clinically valid disulfiram alcohol reactions at 100, 200, and 300 mg doses of disulfiram, respectively. The mean plasma concentrations of Me-DTC at steady-state were proportional to the disulfiram doses given, compared within groups at different doses, and between groups at equal and different optimal doses of the drug. The concentrations of Me-DTC were significantly increased, as compared above, whereas the blood concentrations of acetaldehyde were not significantly increased. The increased plasma concentration of Me-DTC suggests increased oxidative transformation in those individuals, and is apparently associated with enhanced ALDH activity in hepatocytes, shown by the lower plasma concentrations of acetaldehyde, despite increased concentrations of the inhibitor.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1041
    Keywords: chlorambucil ; prednimustine ; plasma concentrations ; bioavailability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of chlorambucil has been investigated in a cross over study after oral administration of the free drug (10 mg) and its prednisolone ester (prednimustine, 100 mg). The bioavailability of chlorambucil was about five times lower when given as prednimustine as compared to administration of the free drug. The peak plasma concentration was about twice as high and it was obtained more rapidly when the free drug was given. No intact prednimustine could be detected in plasma.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1041
    Keywords: Fibrinolysis ; hypertension ; atenolol ; doxazosin ; tissue plasminogen activator ; plasminogen activator inhibitor ; cholesterol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Disturbances in the fibrinolytic system have been associated with cardiovascular disease and its risk factors. In the present study the effects of an alpha1-adrenoceptor inhibitor (doxazosin) and a selective beta-adrenoceptor blocker (atenolol) on the fibrinolytic system have been evaluated. Eighty four subjects with previously untreated mild to moderate hypertension and elevated serum cholesterol were randomized to receive atenolol or doxazosin in a double-blind study over 6 months. Tissue plasminogen activator(tPA) and plasminogen activator inhibitor (PAI-1) were measured in citrated plasma samples before and after venous occlusion before and at the end of the study period. tPA activity after venous occlusion and tPA capacity were significantly increased after doxazosin as compared to pretreatment values. The fibrinolytic variables did not change in the atenolol group. Thus, doxazosin but not atenolol, improved the activity of the fibrinolytic system in patients with hypertension and an elevated serum cholesterol level. This effect of doxazosin warrants consideration when selecting a first-line antihypertensive drug.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of scientific computing 6 (1991), S. 391-414 
    ISSN: 1573-7691
    Keywords: Navier-Stokes equation ; incompressible ; boundary condition ; boundary layer suppressing ; inflow ; outflow ; open boundary ; well-posedness ; well-posedness in the generalized sense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract The time-dependent Navier-Stokes equation for incompressible fluid flow together with new boundary layer suppressing boundary conditions for open boundaries is investigated. In these new boundary conditions one typically prescribes a high-order derivative of some of the dependent variables. We prove that these boundary conditions give rise to a problem that is well posed in the generalized sense. This means that there exists a unique smooth solution of the linearized problem and that this solution can be estimated by data.
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