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  • 1
    Electronic Resource
    Electronic Resource
    Synergism between 5-HT1B/1D and 5-HT1A receptor antagonists on turnover and release of 5-HT in guinea-pig brain in vivo (1999)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 359 (1999), S. 110-116 
    Details
    ISSN: 1432-1912
    Keywords: Key words 5-HT1B and 5-HT1A receptors ; 5-HT turnover ; 5-HT release ; Guinea pigs ; GR 127935 ; WAY-100635 ; Microdialysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects on 5-HT turnover (5-HIAA/5-HT ratio) and extracellular 5-HT and 5-HIAA levels (in vivo microdialysis in freely moving animals) were analysed in guinea-pig brains following the 5-HT1B receptor antagonist, GR 127935 {N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2’-methyl-4’-(5-methyl-1,2,4-oxadiazol-3-yl) [1,1-biphenyl]-4-carboxamide}, or the 5-HT1A receptor antagonist, WAY-100635 (N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride), administered alone or in combination. GR 127935, injected alone, increased 5-HT turnover with maximal effects approximately 50% above the control levels in the four brain regions examined (hypothalamus, hippocampus, striatum and frontal cortex). GR 127935 significantly increased extracellular concentrations of 5-HT and 5-HIAA in frontal cortex (40%), whereas 5-HIAA, but not 5-HT, was elevated in striatum (20–30%). WAY-100635 did not significantly change 5-HT turnover but caused a small significant increase in the extracellular 5-HT and 5-HIAA concentrations in both striatum and frontal cortex. The combined treatment with GR 127935 and WAY-100635 resulted in an increased 5-HT turnover reaching maximal effects of 70–90% above the control values in all brain regions tested and produced a significant elevation of striatal and frontal cortex extracellular 5-HT (40% and 60%, respectively) and 5-HIAA (60% and 70%, respectively) concentrations. The synergistic effect of the two receptor antagonists on the 5-HT turnover and the terminal release of 5-HT indicate somatodendritic 5-HT release and stimulation of inhibitory 5-HT1A receptors at this level. Extracellular 5-HIAA seems to be a better marker than 5-HT itself for the evoked 5-HT release when the reuptake mechanism is intact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005329
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Finite elastoplastic deformation of an internally pressurized hollow sphere (1993)
    Springer
    Acta mechanica solida Sinica 6 (1993), S. 81-97 
    Details
    ISSN: 0894-9166
    Keywords: finite deformation ; dilatant soil ; cavity expansion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper considers large elastoplastic deformations of an internally pressurized hollow sphere of dilatant soil. A complete analytical solution for the expansion of a hollow sphere is developed. The soil is modelled as an elastic-perfectly plastic material obeying the Mohr-Coulomb yield criterion. A non-associated plastic flow rule is used and therefore the dilation of the material is fully taken into account. Closed form solutions are obtained for the stresses and the elastic-plastic deformations of arbitrary magnitude when a hollow sphere of soil is subjected to constant external pressure and monotonically increasing internal pressure. A selection of numerical results is presented to indicate the effects of various key parameters
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02207816
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Quantitative differences in sperm cells and organelles of tobacco (Nicotiana tabacum L.) grown under differing environmental conditions (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 814-817 
    Details
    ISSN: 1432-2242
    Keywords: Cytoplasmic inheritance ; Environmental conditions ; Nicotiana tabacum ; Sperm cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In flowers grown at warm temperatures in environmental chambers and at cooler temperatures in the greenhouse, eight parameters of the sperm-cell organization of Nicotiana tabacum were examined during sperm cell maturation using serial ultrathin sectioning, transmission electron microscopy and quantitative cytology. Despite employing the same seed source, and similar soil and nutrient conditions, the surface area and volume of the cell, the nucleus and the chondriome were larger in flowers grown in growth chambers under warmer controlled conditions, whereas the number of plastids appeared to be the same, or slightly higher, in flowers grown under cooler greenhouse conditions. These results suggest that environmental conditions may influence the quantity of cytoplasmic organelles, including mitochondria and plastids, thus potentially influencing the likelihood of male cytoplasmic inheritance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224502
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Sperm cells in pollen tubes ofNicotians tabacum L.: three-dimensional reconstruction, cytoplasmic diminution, and quantitative cytology (1992)
    Springer
    Protoplasma 168 (1992), S. 172-183 
    Details
    ISSN: 1615-6102
    Keywords: Cytoplasmic inheritance ; Male cytoplasmic diminution ; Male gamete (angiosperm) ; Male germ unit ; Nicotiana ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The organization of the sperm cells and vegetative nucleus (male germ unit) ofNicotiana tabacum was examined 18 h after semivivo pollination using transmission electron microscopy, computerassisted serial section reconstruction and quantitative cytology. Based on a measurement of 11 cellular parameters in nine reconstructed sperm cell pairs, there are no statistically significant differences between the two cells. The Svn is characterized by a strapshaped cytoplasmic extension that is physically associated with the surface of the vegetative nucleus. The nucleus is located adjacent to the sperm crosswall, with sperm organelles being distributed between the nucleus and the extension. The Sua is a tapered cell with cytoplasmic areas at both poles and deep axial invaginations near the crosswall. This cell has a centrally-located nucleus and a largely polar distribution of organelles. Three mechanisms for cytoplasmic diminution were observed that appear to contribute actively to the loss of cytoplasmic volume and organelles: (1) enucleated cytoplasmic body production in the Sua; (2) vesiculation at the tip of the cytoplasmic projection of the Svn; and (3) vesicle-containing body accumulation in the periplasm of both the Svn and Sua.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666263
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  • 5
    Electronic Resource
    Electronic Resource
    UNDRAINED CAVITY EXPANSIONS IN CRITICAL STATE SOILS (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 20 (1996), S. 489-516 
    Details
    ISSN: 0363-9061
    Keywords: cavity expansion ; critical state models ; plasticity ; pile installation ; normally and overconsolidated clays ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Boundary value problems for hardening/softening soils, such as Cam-Clay, usually require the extensive use of finite element methods. Here analytical and semi-analytical solutions for the undrained expansion of cylindrical and spherical cavities in critical state soils are presented. The strain is finite, the initial cavity radius is arbitrary and the procedure applicable to any isotropically hardening materials. In all cases only simple quadratures are involved, and in the case of the original Cam-Clay a complete analytical solution can be found. In addition to providing models of the behaviour of displacement piles and pressuremeters these results also provide valuable benchmark solutions for verifying various numerical methods.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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