Search results for "Concentration."
showing 10 items of 1849 documents
Quantitative Untersuchungen am Meerschweinchenvorhof �ber die Abh�ngigkeit der Digitoxigenin wirkung von der extracellul�ren Calciumkonzentration
1963
Es wurde uber einen weiten Bereich die Calciumkonzentration der Tyrodelosung verandert (0,9–9,0 mAq/l) und unter diesen Bedingungen die Konzentrationswirkungsbeziehungen fur verschiedene Digitoxigenindosen (1 × 10−7, 3 × 10−7, 5 × 10−7, 7 × 10−7 und 1 × 10−6 g/ml) am Meerschweinchenvorhof untersucht. Aus den Befunden geht hervor, das uber den gesamten untersuchten Bereich unter therapeutischen und toxischen Bedingungen ein eindeutiger Wirkungszusammenhang zwischen Digitoxigenin und Calcium besteht.
New ursolic and betulinic derivatives as potential cytotoxic agents.
2003
Fifteen new ursolic and betulinic triterpenoids, bearing various functionalities at C-3 and C-28 were synthesized as potential cytotoxic agents. All compounds were obtained by a hemisynthetic route via ursolic and betulinic acids. Preliminary screening of these compounds on human HT 29 colon cancer cells revealed inhibitory activity for three of them. Beta-D-Glucopyranosyl-3beta-hydroxyurs-12(13)-en-28-oate 1c, 3beta-3-(3-pyridyl)-prop-2-enoyloxyurs-12(13)-en-28-oic acid 1i and the potassium salt of 3beta-cinnamoyloxylup-20(29)-en-28-oic acid 2d demonstrated cytotoxic activity in the micromolar range: 8.0, 45.0 and 8.0 microM, respectively.
Aaptamine Derivatives from the Indonesian Sponge Aaptos suberitoides
2013
Four new aaptamine derivatives (1-4) along with aaptamine (5) and three related compounds (6-8) were isolated from the ethanol extract of the sponge Aaptos suberitoides collected in Indonesia. The structures of the new compounds were unambiguously determined by one- and two-dimensional NMR and by HRESIMS measurements. Compounds 3, 5, and 6 showed cytotoxic activity against the murine lymphoma L5178Y cell line, with IC(50) values ranging from 0.9 to 8.3 μM.
Kinetics and state-dependent effects of verapamil on cardiac L-type calcium channels.
1996
The voltage dependence and the kinetics of block by verapamil of L-type calcium current (ICa) were investigated in ventricular myocytes from rat hearts using the whole-cell patch-clamp technique. ICa was elicited repetitively in response to depolarizing voltage pulses from -80 mV to 0 mV at different pulse intervals and durations. Verapamil reduced the magnitude of ICa in a frequency-dependent manner without tonic component. The time course of ICa remained unchanged suggesting that not open but inactivated channels were affected by the drug. The interaction of verapamil with inactivated channels was investigated by the application of twin pulses. In the presence of verapamil, the duration o…
Toxicokinetics of xenobiotics in zebrafish—Comparison between tap and river water
1991
Abstract 1. 1. Uptake and elimination of lindane, 3,4-dichloroaniline, phenol and 4-nitrophenol by the zebrafish Brachydanio rerio were investigated in tap water and in water of the river Rhine. 2. 2. The differences in bioconcentration of chemicals between the two water types did not exceed a factor of 2.5. 3. 3. Elimination kinetics were comparable in tap and river water. 4. 4. It can be concluded that water of the river Rhine does not influence the kinetics of the investigated xenobiotics.
pH-dependent hydrolysis of acetylcholine: Consequences for non-neuronal acetylcholine
2015
Acetylcholine is inactivated by acetylcholinesterase and butyrylcholinesterase and thereby its cellular signalling is stopped. One distinguishing difference between the neuronal and non-neuronal cholinergic system is the high expression level of the esterase activity within the former and a considerably lower level within the latter system. Thus, any situation which limits the activity of both esterases will affect the non-neuronal cholinergic system to a much greater extent than the neuronal one. Both esterases are pH-dependent with an optimum at pH above 7, whereas at pH values below 6 particularly the specific acetylcholinesterase is more or less inactive. Thus, acetylcholine is prevente…
Synthese, Verteilung und Ausscheidung von 14C markiertem 2-Phenyl-3-methyl-tetrahydro-1,4-oxazin (Preludin)
1958
A radioactive preludin preparation, C14 labelled on the 2-carbon of the tetrahydrooxazine ring, was injected into mice in doses of 100 mg/kg s.c. and rats in doses of 10 mg/kg i.v. The radioactivity of the tissues and excreta was followed for 48 hours. An activity concentration surpassing the average body concentration was obtained for a short time in the lungs and for a longer time in kidneys, liver and in the wall of stomach and small intestine. 95–99% of the total activity is found in the urine. The kidney excretion is virtually finished at the end of 8 hours; 1–5% appear after the 8th hour in faeces. No radioactivity was obtained from the expired CO2. The main excretion organs are kidne…
New high piezoelectric coupling PLuNT binary system ceramics
1999
Abstract The new (1 − x)Pb( Lu 1 2 Nb 1 2 ) O 3 − x PbTiO 3 binary system ceramics in the interval 0 0.49). The morphotropic region extends over the interval x = 0.38–0.49, the concentration ratio M:T ≅ 1 corresponds to x = 0.41. The maximum values of the electromechanical coupling coefficients k p = 0.663, k t = 0.481, k 31 = 0.355 of (1 − x)PLuN-xPT ceramics were attained in compositions PLuNT 59/41 (T m = 353 °C) near the morphotropic phase boundary (MPB). The PLuNT system, having large values of electromechanical coupling and the highest T m (> 350 °C) among binary Pb(B′,B″)O 3 -PT perovskites may be favorable for piezoelectric sensors and actuators, and may have an interest as promisin…
Phase transitions in modified Na 1/2 Bi 1/2 TiO 3 ‐SrTiO 3 solid solutions
2009
Continuous transfer from relaxor to normal ferroelectric phase transition is found in Na1/2Bi1/2TiO3-SrTiO3-PbTiO3 if concentration of PbTiO3 increases. The relaxor properties in NBT solid solutions are described by the power law and Vogel-Fulcher relationship, and concentration dependence of the relevant parameters is discussed. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase Transitions in Na1/2Bi1/2TiO3-SrTiO3-PbTiO3Solid Solutions
2010
All sequential steps of transfer from relaxor to normal ferroelectric phase transition are found in Na1/2Bi1/2TiO3-SrTiO3-PbTiO3 if concentration of PbTiO3 increases. The relaxor properties in Na1/2Bi1/2TiO3-SrTiO3-PbTiO3 solid solutions are described by the power law and Vogel-Fulcher relationship. Concentration dependence of the relevant parameters is discussed. Stability of relaxor and ferroelectric phases is discussed by analyzing behaviour of critical electric fields.