Bibliothek

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Catechin production by callus cultures of Fagopyrum esculentum
    Amsterdam : Elsevier
    Phytochemistry 31 (1992), S. 1239-1241 
    Details
    ISSN: 0031-9422
    Schlagwort(e): (+)-catechin ; (-)-epicatechin ; (-)-epicatechin-3-O-gallate production ; Fagopyrum esculentum ; Polygonaceae ; callus ; plant tissue culture ; polyphenols
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1016/0031-9422(92)80267-I
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Grid stage modelling functions and molecular vector graphics (1986)
    Springer
    The visual computer 2 (1986), S. 367-378 
    Details
    ISSN: 1432-2315
    Schlagwort(e): Molecular polymodelling ; POLYMOD ; 3D Grid stage ; COOBOX ; Geometric and Boolean operations ; Composite images
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01952421
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Cooperativity of tetrodotoxin action in the frog node of Ranvier (1985)
    Springer
    Pflügers Archiv 405 (1985), S. 237-243 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Node of Ranvier ; Na channels ; Tetrodotoxin ; Cooperativity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00582567
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Late sodium current in the node of Ranvier (1975)
    Springer
    Pflügers Archiv 357 (1975), S. 145-148 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Sodium Permeability ; Delayed Currents ; Node of Ranvier
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Voltage clamp experiments carried out on nodes of Ranvier of myelinated fibres ofRana esculenta showed that a small fraction of sodium channels fail to inactivate. Thus during long lasting depolarizing pulses there is a small Na-current superimposed on the leakage and potassium currents. This late Na-current appears more marked in sensory fibres than in motor ones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00584552
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    The steady-state potassium conductance of the ranvier node at various external K-concentrations (1977)
    Springer
    Pflügers Archiv 370 (1977), S. 185-194 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Node of Ranvier ; Potassium conductance ; Cation selectivity ; Gating mechanism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Voltage clamp experiments were carried out on single myelinated fibres of the frog to analyse the changes of the potassium conductance (g K ) resulting from variations of the external K-concentration ([K]0). The use ofg K is justified by the observation that instantaneous K-currents vary linearly withE despite asymmetries between [K]0 and [K]i. 2. At constant membrane potential and for inward going currents,g K increases as a Michaëlian function of [K]0. We propose, therefore, that external K-ions bind specific membrane sites controllingg K . The apparent equilibrium constant (K app ) of the binding reaction decreases with depolarization following a double exponential function. The rate constants of this function depend on the external Ca-concentration. 3. An empirical equation is derived which satisfactorily describes the variation ofg K as a function ofE and [K]0. The fact that either the increase in [K]0 or the membrane depolarization can lead to the opening of the channels is regarded as evidence that the binding of K to specific sites (“K-receptors”) is a necessary step for the formation of conducting channels. The affinity of the receptor-sites for K-ions depends on the electrical field in the membrane. 4. K-free Ringer solutions markedly reduce the steady-state K-current and its rate of activation. These effects are not observed if the lack of potassium is compensated by addition of caesium. It is concluded that Cs can replace K at the sites controlling the formation of the channel. 5. High external concentrations of Cs-ions reduce the inward K-currents when [K]0 is high and tend to increase outward K-currents, especially when [K]0 is low. These results are explained assuming that Cs-ions enter the channel with K-ions moving in single file. They stop the in-moving file when reaching a selectivity structure deeply located in the channel. 6. The fraction of the membrane thickness (δ) at which Cs-ions occupy a blocking position in the K-channel, when K and Cs are present at high concentrations in the external medium, is estimated to be: δ=0.6. From this result, it is deduced that the voltagesensitive K-receptors are located in the external half of the membrane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00581693
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Potassium accumulation in the perinodal space of frog myelinated axons (1975)
    Springer
    Pflügers Archiv 358 (1975), S. 111-124 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Node of Ranvier ; Potassium Permeability ; Ionic Accumulation ; Series Resistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1. Voltage clamp experiments were carried out on frog myelinated fibres to study the origin of the transient inward current occuring when the membrane is repolarized after long lasting depolarizing pulses (tail current denominated “I p” by Frankenhaeuser). 2. The “tail” of inward current measured during repolarization after break of the depolarizing pulse is insensitive to external application of TTX, is abolished by external treatment with TEA or Cs and decreases when the outward K-current during the pulse is diminished. 3. The time course of the “tail” current is exponential. Its direction depends on the duration of the depolarizing pulse and on the membrane potential level at repolarization. 4. It is concluded that the tail of inward current during repolarization is carried by K-ions accumulated in the perinodal space during a depolarizing pulse. The data suggest that the tail reflects the time course of the restoration of the K-concentration to its initial level. The tail current itself contributes to this restoration depending on the Em value at repolarization. 5. It is shown that one of the two phenomenological models proposed by Frankenhaeuser and Hodgkin to account for the external potassium accumulation observed in the squid giant axon may be also applied to the Ranvier node. Assuming that the thickness of the space is 2900 Å and that the K-permeability of the barrier is 0.019 cm/sec, it is possible to account for the observed changes in [K]0 during a long lasting depolarizing pulse. 6. The existence of such a barrier would introduce an electrical resistance in series with the nodal membrane of roughly 150000 Ω.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00583922
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    Cesium induced rectifications in frog myelinated fibres (1975)
    Springer
    Pflügers Archiv 355 (1975), S. 361-364 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Node of Ranvier ; Cs-Ions ; Potassium Channel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Voltage clamp experiments done on nodes of Ranvier show that external application of Cesium blocks the inward but not the outward potassium currents. Internal application of Cs ions reduces the outward K-current and the inward K-current is not affected. These results support the hypotheses that K ions cross the K-channel after dehydration at superficial sites where competition may occur with Cs-ions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00579857
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...