Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Engineering  (9)
  • Rat portal vein  (3)
  • kinetics  (3)
  • 23.20.Lv  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Characterization of the angiotensin II-receptor subtype in the longitudinal smooth muscle of the rat portal vein (1993)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 347 (1993), S. 220-224 
    Details
    ISSN: 1432-1912
    Keywords: Angiotensin II-receptor ; Dithiothreitol ; Nonpeptide angiotensin II-receptor antagonists ; Rat portal vein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of the present study was to identify the angiotensin II-receptor subtype involved in the enhancement of the amplitude of the phasic contractions by angiotensin II in the isolated rat portal vein preparation. At an extracellular Ca2+ concentration of 0.9 mmol/l and a K+ concentration of 4 mmol/l, angiotensin II induced concentration-dependent increases in the amplitude of the phasic contractions. The enhancement of phasic contraction amplitude caused by angiotensin II was not significantly altered by pretreatment of the rat portal vein with indomethacin 10−5 mol/l or nitro-L-arginine 10−4 mol/l, indicating that neither prostaglandins nor the endothelium derived-relaxing factor (NO) are involved. Losartan (DuP 753), a nonpeptide selective AT1-receptor antagonist, concentration-dependently shifted the concentration-response curve for the effect of angiotensin II on the amplitude of the contractions to the right, without reducing the maximal response (pA2 = 8.6, slope = 0.98), thus suggesting competitive antagonism at the level of AT1-receptors. By contrast, PD 123177, a nonpeptide selective AT2-receptor antagonist, even at 10−5 mol/l, caused no significant change of the phasic myogenic response to angiotensin II, indicating the absence of AT2-receptor involvement. Dithiothreitol, a disulfide-reducing agent which is known to inactivate AT1-receptors in various tissues, markedly inhibited (3 mmol/l) or even abolished (5 mmol/l) the contractile response of the rat portal vein to angiotensin II, supporting the conclusion that these receptors can be classified as AT1-receptors. In conclusion, the receptor subtype mediating the angiotensin II-induced potentiation of the spontaneous phasic contractions in the rat portal vein appears to belong to the AT1-receptor subtype.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169271
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Inhibitory effect of dithiothreitol on angiotensin II-induced contractions mediated by AT1-receptors in rat portal vein and rabbit aorta (1994)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 349 (1994), S. 538-542 
    Details
    ISSN: 1432-1912
    Keywords: AT1-receptors ; Angiotensin II ; Dithiothreitol ; Losartan ; Rat portal vein ; Rabbit aorta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The disulfide-reducing agent dithiothreitol (DTT) has been shown to reduce angiotensin II (Ang II) subtype 1 receptor (AT,) binding sites in various tissues. Its effect on Ang II-induced contractions was studied in the rat portal vein and rabbit aorta. In the isolated rat portal vein, DTT shifted the concentration-response curve for Ang II to the right (DTT 0.5–3 mmol/l) and depressed the maximal response (DTT 1–3 mmol/l). DTT 5 mmol/l almost abolished the effect of Ang II. In the isolated rabbit aorta, the inhibitory effect of DTT was more pronounced and its pattern of effect was different,since DTT 0.3 and 0.5 mmol/l caused a progressive flattening of the concentration-response curve of Ang II. DTT (1 mmol/l) fully suppressed the effect of Ang II. A biphasic curve consisting of a high sensitivity component and a component of low sensitivity for Ang II was observed after pretreatment with DTT 1 mmol/l in the rat portal vein but not in the rabbit aorta. In the presence of DTT 1 mmol/l, the AT1-receptor antagonist losartan antagonized the high sensitivity response to Ang II in a competitive manner with a pA2 value very similar to that obtained in the absence of DTT, suggesting that this response to Ang II is mediated by those AT1-receptors which were not inactivated by DTT The biphasic curve may be explained by the occurrence of a single AT1-receptor subtype existing in two different states. Another possibility might be the involvement of two AT1-receptor subpopulations. It is concluded that disulfide bonds are critical for the functional role of AT1-receptors in Ang II-induced contractions in the rat portal vein and rabbit aorta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169144
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Calcium dependency of the AT1-receptor mediated effects in the rat portal vein: influence of calcium antagonists (1994)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 349 (1994), S. 437-442 
    Details
    ISSN: 1432-1912
    Keywords: Ang II ; AT1-receptor ; Calcium ions ; Calcium antagonists ; Rat portal vein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The calcium dependency of AT1-receptor mediated contractions was studied in isolated rat portal vein preparations. The spontaneous phasic contractile force of the rat portal vein was increased (ED50 = 1.76 mmol/l) and the frequency of contractions decreased by raising the extracellular calcium concentration. The Ang 11-induced rise in phasic contractile force (mediated by AT1-receptors, Zhang et al. 1993) proved most pronounced at 0.9 mmol/l of calcium chloride, but it was weaker at either lower or higher calcium concentrations. The maximal increases in the phasic contractile force induced by Ang II were 2.4±0.4, 14.8±0.9 and 5±0.5 mN at calcium concentrations of 0.5, 0.9 and 2.5 mmol/l, respectively. Calcium antagonists reduced at the lower and abolished at the higher concentrations (nifedipine 2×10−8 or 10−7 mol/l; verapamil 10−7 or 5 × 10−7 mol/l; diltiazem 3 × 10−7 or 10–6 mol/l) the spontaneous contractile force. All of these calcium antagonists caused a strong inhibition or suppression of the phasic contractions induced by Ang II.The rank order of potency was nifedipine 〉verapamil 〉 diltiazem. Ang II (10−6 mol/l) elicited a tonic contraction which was abolished by the AT1-receptor antagonist losartan 10-6 mol/l but not by the AT2-receptor antagonist PD 123177 (10–5 mol/l). Very high concentrations of nifedipine (10–6 mol/l), verapamil (5 × 10-6 mol/l) and diltiazem (5 × 10−6 mol/l) almost suppressed the tonic effect evoked by the activation of AT1-receptors. In a nominally Ca2+ “free”, EGTA-containing solution, a single supra-maximal concentration of Ang II (10−6 mol/l) caused a transient contraction, also mediated by AT1-receptors. This finding suggests the existence of Ang II-sensitive intracellular calcium stores in this preparation. The depletion of such stores proved complete after 4–6 min of perfusion in a Ca2+ “free”, EGTA-containing solution. In conclusion, various types of contractions (a transient contraction in a Ca2+-“free” medium, phasic and tonic contractions) induced by Ang II in the rat portal vein proved to be mediated by AT1-receptors. These contractions were clearly modified by changes in the availability of extra- and possibly intracellular calcium ions. The calcium movements elicited by stimulation of AT1-receptors in a calcium containing solution were inhibited by the three calcium antagonists investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00170892
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    First identification of high spin states in160Lu (1995)
    Springer
    The European physical journal 351 (1995), S. 241-242 
    Details
    ISSN: 1434-601X
    Keywords: 23.20.Lv ; 25.70.Gh ; 27.70.+q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A rotational band of160Lu was identified for the first time through the144Sm(19F,3n)160Lu reaction with a beam energy of 90 MeV. A γ-γ-BGO coincidence experiment was performed using five HpGe-BGO Compton-Suppressed spectrometers and a 14 elements ball of BGO detectors. The highest spin of the band with π9/2−[514]⊗v1/2+[660] could be pushed up to 21−, and it shows the feature of an anomalous signature splitting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290902
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Study of the yrast band in the doubly odd156Tm (1995)
    Springer
    The European physical journal 352 (1995), S. 115-116 
    Details
    ISSN: 1434-601X
    Keywords: 23.20.Lv ; 27.70.+q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The yrast band in the doubly odd156Tm nucleus was studied through144Sm(19F,2p5n)156Tm reaction at beam energy of 105MeV. Several high-spin states of156Tm were identified and the highest spin of the band with configurationπ7/2−[523] ⊗v1/2+[660] could be built up to spin 25ħ. The level structure shows the onset of a non- or weak collectivity which generally appears at neutron number of 87 in neutron-deficient rare-earth nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01298894
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Are cell redox or lactate dehydrogenase kinetics responsible for the absence of gluconeogenesis from lactate in sea raven, hepatocytes? (1994)
    Springer
    Fish physiology and biochemistry 13 (1994), S. 59-67 
    Details
    ISSN: 1573-5168
    Keywords: fish ; sea raven ; gluconeogensis ; hepatocytes ; redox ; LDH ; isozymes ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous studies have reported very low rates of gluconeogenesis from lactate in sea raven (Hemitripterus americanus) hepatocytes compared to other teleosts studied. This study examines whether hepatic cell redox or lactate dehydrogenase (LDH) characteristics may explain this observation. Sea raven hepatic optimal LDH activities (pyruvate reductase direction) were more than 40 times less compared with rainbow trout liver values (40 vs 1914 μmol·min−1·g−1 protein). The Km(lactate) was 9.24 and 0.86 mM for sea raven and trout hepatic LDH, but the Km(pyruvate) was similar between the two species (0.11 and 0.21 mM, respectively). These results suggested that sea raven liver LDH did not favour lactate use and was more indicative of the mammalian M-isozyme. Gel electrophoresis showed a predominant intermediate isozyme, with a small amount of the M-type LDH. Phosphoenolpyruvate carboxykinase (PEPCK) was localized to the mitochondrial compartment, while there was no apparent mitochondrial glutamate-oxaloacetate transaminase (GOT) activity. No in vitro lactate flux to glucose was found in untreated, 10 mM ethanol-treated, or 3 mM NH4Cl-treated sea raven hepatocytes, although CO2 production from lactate was decreased by ethanol and increased by NH4Cl. These results provide evidence that cell redox does not limit gluconeogenesis from lactate, while low activities and the kinetic characteristics of LDH may partially explain the low lactate gluconeogenesis reported in sea raven hepatocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004120
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Studies on Non-isothermal Kinetics of the Thermal Decomposition of Eu2(BA)6(bipy)2 (2000)
    Springer
    Journal of thermal analysis and calorimetry 62 (2000), S. 747-755 
    Details
    ISSN: 1572-8943
    Keywords: benzoic acid ; europium complex ; kinetics ; non-isothermal ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal decomposition of Eu2(BA)6(bipy)2 (BA=C2H5N– 2, benzoate; bipy=C10H8N2, 2,2'-bipyridine)and its kinetics were studied under the non-isothermal condition by TG-DTG, IR and SEM methods. The kinetic parameters were obtained from analysis of the TG-DTG curves by the Achar method, the Madhusudanan-Krishnan-Ninan (MKN) method, the Ozawa method and the Kissinger method. The most probable mechanism function was suggested by comparing the kinetic parameters. The kinetic equation for the first stage can be expressed as: dα/dt=Aexp(–E/RT)3(1–α)2/3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026785727479
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    In situ studies of epitaxial silicon growth by gas source molecular beam epitaxy (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 7 (1997), S. 215-224 
    Details
    ISSN: 1057-9257
    Keywords: silicon ; epitaxy ; kinetics ; dynamics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: The value of in situ monitoring to study growth dynamics and surface reaction kinetics in a gas source molecular beam epitaxy process is illustrated with reference to the growth of Si films on Si(001) substrates using a beam of disilane (Si2H6). By using a combination of reflection high-energy electron diffraction (RHEED) and reflection anisotropy spectroscopy (RAS), we show first how morphological (long-range order) and local electronic structure effects can be separated in the evaluation of growth dynamics. This involves the measurement of step density changes by RHEED concomitantly with the variation in domain coverage on the Si(001) (2×1)+(1×2) reconstructed surface by RAS. This approach is then extended to investigate the kinetics of hydrogen desorption, which is the rate-limiting step in Si growth from Si2H6. It is shown that over a significant temperature range, zeroth-order kinetics are obeyed and this is explained on the basis of a step-mediated desorption process. Finally we show how this influences the growth rate on substrates of differing degrees of vicinality. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    A semi-analytic method for dynamic response analysis based on Gurtin's variational principle (1995)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 11 (1995), S. 297-306 
    Details
    ISSN: 1069-8299
    Keywords: semi-analytic method ; dynamic response ; convolution ; variational principle ; series ; finite element method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In the paper a semi-analytic approach for solving dynamic response problems is developed which is based on Gurtin's convolution-type variational principle. A finite element discretization in the space domain and a series representation in the time domain are considered. This approach overcomes the shortcomings of existing methods yet utilizes their advantages for solving dynamic response problems. The example of a beam shows that this new approach is a very effective method in obtaining solutions for dynamic response problems. The paper also concentrates on utilizing time domain series for various boundary conditions, so that solutions calculated by this approach have a very high accuracy and efficiency.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cnm.1640110403
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A six-node finite element for plate bending (1985)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 21 (1985), S. 131-143 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A six-node plate bending element has been developed by employing mixed formulation based on a modified Hellinger-Reissner principle and the Reissner-Mindlin plate bending theory. The numerical result indicates that, among the types of assumed independent transverse shear strains considered, a combination of 2α version with either 5α version or 6α version is free of spurious kinematic modes and leads to accurate and reliable solutions even for very thin plates.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620210111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...