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  • Articles: DFG German National Licenses  (15)
  • Polymer and Materials Science  (8)
  • Life and Medical Sciences  (5)
  • Ventricle  (2)
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  • Articles: DFG German National Licenses  (15)
Material
Years
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Characteristics of the delayed rectifier K current compared in myocytes isolated from the atrioventricular node and ventricle of the rabbit heart (1996)
    Springer
    Pflügers Archiv 431 (1996), S. 713-722 
    Details
    ISSN: 1432-2013
    Keywords: Atrioventricular node ; Myocyte ; Ventricle ; Delayed rectifier potassium current (I k) ; E-4031
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The delayed rectifier potassium current (I K) is known to be important in action potential repolarisation and may contribute to the diastolic pacemaker depolarisation in pacemaker cells from the heart. In this study, using whole-cell patch clamp, we investigated the characteristics ofI K in morphologically normal cells from the atrioventricular node (AVN) and ventricle of the rabbit heart. Cells were held at −40 mV and 5 μM external nifedipine was used to block L-type calcium current (I Ca,L). SignificantI K was observed with pulses to potentials more positive than −30 mV. The steady-state activation curve in both cell types showed maximal activation at between + 10 and + 20 mV. Half-maximal activation ofI K occurred at −4.9 and −4.1 mV with slope factors of 8.3 and 12.4 mV in ventricular and AVN cells, respectively. Using pulses of increasing duration, significantI K tails after repolarisation from + 40 mV were observed with pulses of 20 ms and increased with pulses up to 100–120 ms in both cell types. Pulses of longer duration did not activate furtherI K and this suggested that only the rapid component ofI K, calledI Kr, was present in either cell type. Moreover,I K tails after pulses to all potentials were blocked completely by E-4031, a selective blocker ofI Kr. The reversal potential ofI K varied with the concentration of external K. Superfusion of AVN cells with medium containing 4, 15 and 40 mM [K+]o resulted in reversal potentials of −81, −56 and −32 mV respectively, which are close to values predicted if theI K channel were highly selective for K. The time constants for deactivation ofI K in ventricle and AVN on return to −40 mV after a 500-ms activating pulse to + 60 mV were 480 ms and 230 ms, respectively. The faster deactivation ofI K in AVN cells was a distinguishing feature and suggests that there may be differences in theI Kr channel protein between ventricular and AVN cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253834
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Characteristics of the delayed rectifier K current compared in myocytes isolated from the atrioventricular node and ventricle of the rabbit heart (1996)
    Springer
    Pflügers Archiv 431 (1996), S. 713-722 
    Details
    ISSN: 1432-2013
    Keywords: Key words Atrioventricular node ; Myocyte ; Ventricle ; Delayed rectifier potassium current (Ik) ; E-4031
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The delayed rectifier potassium current (I K) is known to be important in action potential repolarisation and may contribute to the diastolic pacemaker depolarisation in pacemaker cells from the heart. In this study, using whole-cell patch clamp, we investigated the characteristics of I K in morphologically normal cells from the atrioventricular node (AVN) and ventricle of the rabbit heart. Cells were held at −40 mV and 5 μM external nifedipine was used to block L-type calcium current (I Ca,L). Significant I K was observed with pulses to potentials more positive than −30 mV. The steady-state activation curve in both cell types showed maximal activation at between + 10 and + 20 mV. Half-maximal activation of I K occurred at −4.9 and −4.1 mV with slope factors of 8.3 and 12.4 mV in ventricular and AVN cells, respectively. Using pulses of increasing duration, significant I K tails after repolarisation from + 40 mV were observed with pulses of 20 ms and increased with pulses up to 100–120 ms in both cell types. Pulses of longer duration did not activate further I K and this suggested that only the rapid component of I K, called I Kr, was present in either cell type. Moreover, I K tails after pulses to all potentials were blocked completely by E-4031, a selective blocker of I Kr. The reversal potential of I K varied with the concentration of external K. Superfusion of AVN cells with medium containing 4, 15 and 40 mM [K+]o resulted in reversal potentials of −81, −56 and −32 mV, respectively, which are close to values predicted if the I K channel were highly selective for K. The time constants for deactivation of I K in ventricle and AVN on return to −40 mV after a 500-ms activating pulse to + 60 mV were 480 ms and 230 ms, respectively. The faster deactivation of I K in AVN cells was a distinguishing feature and suggests that there may be differences in the I Kr channel protein between ventricular and AVN cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050056
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Block copolymers by metathesis polymerisation (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 325-330 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A transformation reaction from anionic to metathesis was used to prepare block copolymers of styrene and cyclopentene. The composition of the products was established by elemental and UV analysis. A mechanism for the formation of the propagating centre in the olefin metathesis reaction was postulated that will account for the incorporation of the alkyl group of the cocatalyst in the first formed metal carbene.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860211
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  • 4
    Electronic Resource
    Electronic Resource
    Studies in ring-opening polymerization. The kinetics of the reactions between tungsten hexachloride and cyclopentene: A study of the metathesis initiation reaction (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2121-2139 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The complex series of reactions that takes place between WCl6 and cyclopentene was studied spectroscopically. The products of reaction remain soluble when chlorobenzene is used as solvent. A number of intermediates was observed and the kinetics of formation and removal of these was studied in detail. A complex series of reactions was postulated to account for these changes and the significance of each reaction to the overall scheme was determined by computer simulation of the changes that occur. One of the products has particular significance in the scheme of reactions since it is believed that this species is eventually responsible for the monometallic initiation of the polymerization of cyclopentene. The reaction was also studied gas chromatographically when it was shown that the reaction is accompanied by the formation of a complex mixture of products. One of these products was shown to have the mass spectrum that would be expected of 3-chlorocyclopentene and a reaction scheme that would account for its formation is postulated. The reactions involved in the generation of centres active towards the formation of polypentenamer were considered for both monometallic and bimetallic (WCl6/AlR3) catalyst.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880910
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  • 5
    Electronic Resource
    Electronic Resource
    Studies in electroactive polymers, 2Part 1: cf.13. Soluble polyacetylene: A new synthetic route (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1635-1639 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyacetylene-block-polystyrene was synthesized via an anionic-to-metathesis catalysis. The polymers obtained were characterized by UV/visible spectroscopy, IR spectroscopy and gel permeation chromatography.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880710
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  • 6
    Electronic Resource
    Electronic Resource
    Studies in ring-opening polymerisation, 10.Part 9: cf. A. J. Amass, A. Dale, B. J. Tighe, Makromol. Chem. 189, 515 (1988). Pyridine-initiated polymerisation of cyclic anhydrocarboxylates of α-mercapto acids (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 199-211 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the pyridine-initiated polymerisation of simple 1,3-oxathiolan-2,5-diones (3a-c) in nitrobenzene was studied at various temperatures. Results show that, although the substituents in 4-position have a marked effect on rate of polymerisation, the polymerisation of the three monomers studied is linked by a common mechanism. Thus, the pyridine, nucleophile attacks the carbonyl in 5-position and forms a charge transfer complex which decomposes to form a highly reactive α-thiolactone intermediate 8 together with carbon dioxide and pyridine. Chain addition continues by the direct attack on the thiolactone by the terminal-SH group of traces of parent acid. The reaction of each of the three monomers with pyridine was found to show first order kinetic dependence on both monomer and pyridine, although the initiator (i.e. pyridine) is not consumed. The resultant polymers (molecular weight typically around 20000) are highly crystalline and relatively insoluble in common organic solvents.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021910116
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  • 7
    Electronic Resource
    Electronic Resource
    Studies in electroactive polymers, 3Part 1: A. J. Amass, M. S. Beevers, T. R. Farren, J. A. Stowell, Makromol. Chem., Rapid Commun. 8, 119 (1987); Part 2: J. A. Stowell, A. J. Amass, M. S. Beevers, T. R. Farren, Makromol. Chem. 188, 1635 (1987).. Synthesis of cyclopentene/acetylene copolymers using metathesis catalysts (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2535-2541 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymers containing acetylene and pentenamer units were synthesized by sequential addition of cyclopentene and then acetylene to an active metathesis catalyst system. The formation of block copolymers was indicated by UV-vis spectroscopy, gel permeation chromatography and infra-red spectroscopy.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021881105
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  • 8
    Electronic Resource
    Electronic Resource
    Studies in ring-opening polymerization, 9.Part 8: A. J. Amass, M. Lotfipour, I. A. Zurimendi, B. J. Tighe, C. Thompson, Makromol. Chem. 188, 2121 (1987). Co-metathesis of cyclic alkenes and unsaturated esters (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 515-522 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization of cyclopentene in the presence of an unsaturated ester led to the synthesis of low-molecular-weight polypentenamer with a terminal functional group by ringopening metathesis polymerization using WCl6/AlEtCl2/EtOH as catalyst. Unlike most reactions of this nature the efficiency of the catalyst system is high because the ester used possesses an electron withdrawing group, the trichloromethyl group. The presence of this group ensures that the complex formed between the metal carbene complex and the ester group is reduced in stability and catalyst concentrations normally used for ring-opening metathesis polymerizations can be used (mole ratio W : CP = 1 : 1000), the concentrations of ester being quite high (mole ratio ester : CP = 1 : 5). Under these conditions reasonably high yields of liquid polymers are obtained.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890304
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  • 9
    Electronic Resource
    Electronic Resource
    Sexual dimorphism in north American hawks I. Sex organsAided by grants from the National Research Council, Committee for Research on Problems of Sex, grants administered by Prof. Emil Witschi. (1937)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 321-349 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the gonads of the marsh hawk, Circus hudsonius, Cooper's hawk, Accipiter cooperi, and the red-tailed hawk, Buteo borealis borealis has been investigated. The occurrence and relatively long persistence of the cortex on both testes of the marsh hawk is evidence of bilateral amphisexuality in this form. The embryonic condition of the ovaries is related to the degree of asymmetry in the adult organs. Nearly symmetrical, paired ovaries were found in three species and varying amounts of reduction of the right ovary in all others.The disappearance of the right oviduct in the ontogeny of the female red-tailed hawk and the occurrence of accessory gonad tissue in male embryos of the same species are described and figured. The extent of reduction of the right ovary of eleven species is described, figured and classified. The following species are listed in the above order of classification: Circus hudsonius, Accipiter cooperi, Accipiter velox velox, Accipiter atricapillus atricapillus, Falco sparverius sparverius, Aquila chrysaëtos canadensis, Buteo borealis borealis, Buteo lineatus lineatus, Buteo lagopus sancti-johannis, Cathartes aura septentrionalis, Buteo platypterus platypterus.It is concluded that two ways by which organs may disappear are realized in the right ovary and oviduct of the hawks. (1) by failure of an embryonic inductor in the case of the ovary, and (2) in the right oviduct by secondary atrophy of an originally well-developed embryonic structure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050610206
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  • 10
    Electronic Resource
    Electronic Resource
    Sex chromatin and idiograms from rats exhibiting anomalies of the reproductive organs (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 153 (1965), S. 85-91 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Certain anomalous conditions associated with the reproductive organs have arisen in a line of King-Holtzmann hybrid rats maintained in our laboratory. These are sterile pseudohermaphroditic males in which the entire reproductive tract except the testes is missing; apparent males demonstrating an ectopic inguinal ring and testis on one or both sides; and sterile males with descended scrotal testes. The procedure developed by Moore ('55) for staining sex chromatin was applied to cells from liver, spinal cord, testis, and parotid gland of rats. A sex difference is clearly shown, however, only with the liver cells. Ford and Woollam's ('64) sequence for demonstrating mammalian chromosomes renders positive results on bone marrow cells. This method applied to liver and testis yields unsatisfactory results.Examination of idiograms and sex chromatin bodies from animals exhibiting the conditions outlined above leads to the following conclusions: (1) all abnormal animals studied are genetic males; and (2) the pseudohermaphrodites, though genetically male, exhibit a pattern of differentiation of chromosomes during the metaphase plate stage resembling that in the female.Similarities between certain anatomic and physiologic factors exhibited in pseudohermaphroditic rats and those present in “testicular feminization” in man are discussed. Male rats exhibiting an ectopic inguinal ring and testis and sterile males with descended scrotal testes also may have their counterpart in man.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091530110
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