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  • 1
    Electronic Resource
    Electronic Resource
    Phentolamine and hypoxia: modulation of contractility and α1-adrenoceptors in isolated rat atria (1994)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 350 (1994), S. 563-568 
    Details
    ISSN: 1432-1912
    Keywords: Key words:α1-Adrenoceptors –β-Adrenoceptors – Hypoxia – Phentolamine – Atrial function – Yoshida rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The hypoxia-induced effects on the binding sites and affinity constant of adrenoceptors, in the presence and absence of phentolamine, were determined for atrial membranes of hearts from normal and genetically hyperlipidaemic Yoshida (YOS) rats. Atrial function was also measured during normoxia and hypoxia, in the presence and absence of phentolamine.   Hypoxia increased α1-adrenoceptor density in atrial membranes of normal rats (Bmax 10.6 to 26.7 fmoles/mg protein). Phentolamine prevented the increase in the Bmax of α1-adrenoceptors and increased the equilibrium dissociation constant of these receptors (K D 0.17 to 0.53 nmol/l). Beta-adrenoceptors did not change during hypoxia, but the Bmax was slightly increased (26%) in the presence of phentolamine. Thus, the α1/β ratio increased from 0.40 in normoxia to 1.06 in hypoxia. In normoxic atria from YOS rats, the α1/β ratio was already elevated (0.86) in comparison to control rats (mainly due to a higher density of α1-adrenoceptors in atrial membranes from YOS rats). This ratio was not modified by hypoxia (0.84), but decreased when phentolamine was present (0.30).   Hypoxia reduced the force of contraction and increased diastolic tension of atria of normal rats, while the sinus rate was not significantly modified. Phentolamine abolished the increase in diastolic tension and reduced the negative effect of hypoxia on contractile force. In YOS rat atria, functional parameters were modified by hypoxia in a qualitatively similar way to that of normal rat atria.   The observed increase in α1-adrenoceptor density during hypoxia is in accordance with the results of experiments with animal models of the ischaemic heart and with findings in human heart failure. The possible therapeutic significance of these data is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173027
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  • 2
    Electronic Resource
    Electronic Resource
    L-Arginine does not improve endothelium-dependent relaxation inin vitro Watanabe rabbit thoracic aorta (1993)
    Springer
    Amino acids 5 (1993), S. 403-411 
    Details
    ISSN: 1438-2199
    Keywords: Amino acids ; Atherosclerosis ; Endothelium ; Watanabe heritable hyperlipidemic rabbit (WHHL) ; L-Arginine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The findings that even a singlein vitro addition of L-arginine is able to normalize endothelium function in cerebral vessel from diet-induced hypercholesterolemic rabbits prompted us to investigate if similar results could be obtained on Watanabe rabbits thoracic aorta, in which we previously demonstrated low content of the amino acid. L-Arginine (1 mM) preincubated for 45 minutes before the addition of drugs for studing endothelium-dependent vascular relaxation, did not modify the effect of acetylcholine on aortic isolated preparations. The lack of any effect by L-arginine indicates that the amino acid deficiency is not main cause of the impairment of endothelium function. The muscarinic receptor functionality affected by atherosclerotic process and/or the increased synthesis of EDCFs could account for the reduced endothelium-dependent relaxation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00806958
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  • 3
    Electronic Resource
    Electronic Resource
    Phentolamine and hypoxia: modulation of contractility and α1-adrenoceptors in isolated rat atria (1994)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 350 (1994), S. 563-568 
    Details
    ISSN: 1432-1912
    Keywords: α1-Adrenoceptors ; \-Adrenoceptors ; Hypoxia ; Phentolamine ; Atrial function ; Yoshida rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The hypoxia-induced effects on the binding sites and affinity constant of adrenoceptors, in the presence and absence of phentolamine, were determined for atrial membranes of hearts from normal and genetically hyperlipidaemic Yoshida (YOS) rats. Atrial function was also measured during normoxia and hypoxia, in the presence and absence of phentolamine. Hypoxia increased a1-adrenoceptor density in atrial membranes of normal rats (Bmax 10.6 to 26.7 fmoles/mg protein). Phentolamine prevented the increase in the Bmax of α1-adrenoceptors and increased the equilibrium dissociation constant of these receptors (K D 0.17 to 0.53 nmol/l). Beta-adrenoceptors did not change during hypoxia, but the Bmax was slightly increased (26%) in the presence of phentolamine. Thus, the α1/\ ratio increased from 0.40 in normoxia to 1.06 in hypoxia. In normoxic atria from YOS rats, the α1/\ ratio was already elevated (0.86) in comparison to control rats (mainly due to a higher density of at-adrenoceptors in atrial membranes from YOS rats). This ratio was not modified by hypoxia (0.84), but decreased when phentolamine was present (0.30). Hypoxia reduced the force of contraction and increased diastolic tension of atria of normal rats, while the sinus rate was not significantly modified. Phentolamine abolished the increase in diastolic tension and reduced the negative effect of hypoxia on contractile force. In YOS rat atria, functional parameters were modified by hypoxia in a qualitatively similar way to that of normal rat atria. The observed increase in α1-adrenoceptor density during hypoxia is in accordance with the results of experiments with animal models of the ischaemic heart and with findings in human heart failure. The possible therapeutic significance of these data is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173027
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Synthetic fragments and analogues of elastin. I. The synthesis (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 845-854 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of some repetitive sequences of elastin and their simplified analogues, all comprising the structural unit Gly-X-Gly (X = Val, Leu, Ala), is described. In particular, the following peptides and polypeptides were synthesized and characterized: Boc-Gly-Val-Gly-Gly-Leu-OMe, Boc-Gly-Leu-Gly-Gly-Val-OMe, Boc-(Gly-Val-Gly-Gly-Leu)2-OMe, Boc-(Gly-Val-Gly-Gly-Leu)3-OMe, Boc-Gly-Val-Gly-Gly-OEt, Boc-Leu-Gly-Gly-Leu-OMe, Boc-Val-Gly-Gly-Val-OMe, poly(Ala-Gly-Gly), poly(Val-Gly-Gly), and poly (Leu-Gly-Gly).In every case, the synthesis was accomplished by classical procedures in solution, by using the p-nitrophenyl ester method for the polycondensation step, and the mixed anhydride or the azide methods for the coupling steps.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290418
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  • 5
    Electronic Resource
    Electronic Resource
    Synthetic fragments and analogues of elastin. II. Conformational studies (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 855-870 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational studies on synthetic repetitive sequences and analogues of elastin are described.CD and nmr measurements gave evidence of flexible β-turns as the dominant structural feature whose stability was found to decrease by increasing the number of repetitive units. The sequences comprised the structural unit Gly-X-Gly (X = Val, Leu, Ala), with X-Gly or Gly-Gly located at the corners of the bend.Based on that, it is proposed that these regions of elastin, unlike the proline-containing sequences, contribute to the elasticity of the protein through a classical mechanism in terms of the rotational isomeric state theory.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290419
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  • 6
    Electronic Resource
    Electronic Resource
    On the gas-phase reaction of C3O2+. with C3O2 (1994)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 29 (1994), S. 540-546 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase, ion molecule reaction between C3O2+. and C3O2 has been studied by both double-focusing and ion trap mass spectrometry, rationalized by the formation of a dimeric, odd electron cation [C6O4]+. which decomposes extensively through sequential CO losses giving rise to [C5O3]+. and [C4O2]+. ions. The thermodynamics of this process have been investigated by means of ab initio calculation performed on the above species using different basis sets (STO-3G, 3-21G and 6-31G*).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210291005
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Structural investigation of the hydroxy-propynal molecular ion (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 132-137 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A formyl ketenyl platinum derivative, trans-μ1-(PCy3)2(H)Pt[C(CHO)CO] (where Cy represents a cyclohexyl group), when reacted with HCl, gives a C3H2O2 species among the reaction products. The structure was investigated mass spectrometrically by study of the reactions of metastable ions, and the information gained was combined with data from theoretical calculations to rationalize the structure of the C3H2O2 molecule.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290070204
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  • 8
    Electronic Resource
    Electronic Resource
    Gas-phase ion chemistry of carbon suboxide (1994)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 29 (1994), S. 57-59 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210290111
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