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  • 1
    Electronic Resource
    Electronic Resource
    Cooperativity of tetrodotoxin action in the frog node of Ranvier (1985)
    Springer
    Pflügers Archiv 405 (1985), S. 237-243 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Na channels ; Tetrodotoxin ; Cooperativity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 1. The steady state effects and rates of action of tetrodotoxin (TTX) on sodium current were studied in the voltage clamped frog node of Ranvier. 2. Inactivation of the sodium current was separated into fast and slow phases. Both phases were assumed to correspond to two different currents (fast and slow) flowing through fast and slow channels (Benoit et al. 1985). 3. The dose-response curve of the steady state effect of tetrodotoxin on the fast current was sigmoid. An analysis of this effect in double logarithmic coordinates gave a Hill coefficient of 1.74. 4. The rates of tetrodotoxin action on the fast current were determined by the reversible reduction of the peak current recorded at a potential (+20 mV) at which the slow current was relatively small. 5. After an initial delay, the onset of TTX effect followed an exponential function of time whose constant decreased with increasing tetrodotoxin concentrations. Expressed as the time corresponding to a reduction of 2% of the current, the delay (δt2%) increased from about 100 ms with 300 nM-TTX to about 30 s with 1 nM-TTX. 6. When tetrodotoxin was removed, the offset developed quasi-instantaneously and followed an exponential function of time whose constant was independent of the toxin concentration. 7. Both steady state and rates of tetrodotoxin effects could be fitted well if one assumed that the block of one fast channel occurred after binding of two TTX molecules to two cooperative sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582567
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Grid stage modelling functions and molecular vector graphics (1986)
    Springer
    The visual computer 2 (1986), S. 367-378 
    Details
    ISSN: 1432-2315
    Keywords: Molecular polymodelling ; POLYMOD ; 3D Grid stage ; COOBOX ; Geometric and Boolean operations ; Composite images
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A polymodelling system (POLYMOD) is presented for varied 2D or 3D displays of chemical shapes, whether structural (molecular volumes distances, surfaces...) or electronic (molecular electrostatic potential, electron densities ...). The POLYMOD system manages reversible correspondences between calculation and representation spaces by immersing the molecules studied in a unique represetation space structured by a 3D grid box. This box, called COOBOX, defined by its point internal coordinates, is used to transform other coordinates into its own. Direct multi-slice images along thex, y, z axis provide access to a variety of derived operations around a molecular shape or set of shapes disposed in various manners. Interactive sub systems ensure Boolean operations and compare property shapes through the 3D grid. Clear separation of graphic routine and of downstream modelling programs leads to rapid and original generation of varied images (subimages, direct or composite images) which are then available for simulation strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01952421
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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