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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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  • 2
    Electronic Resource
    Electronic Resource
    Late sodium current in the node of Ranvier (1975)
    Springer
    Pflügers Archiv 357 (1975), S. 145-148 
    Details
    ISSN: 1432-2013
    Keywords: Sodium Permeability ; Delayed Currents ; Node of Ranvier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584552
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  • 3
    Electronic Resource
    Electronic Resource
    Potassium accumulation in the perinodal space of frog myelinated axons (1975)
    Springer
    Pflügers Archiv 358 (1975), S. 111-124 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Potassium Permeability ; Ionic Accumulation ; Series Resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583922
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  • 4
    Electronic Resource
    Electronic Resource
    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
    Keywords: Node of Ranvier ; Potassium conductance ; Cation selectivity ; Gating mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581693
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  • 5
    Electronic Resource
    Electronic Resource
    Cesium induced rectifications in frog myelinated fibres (1975)
    Springer
    Pflügers Archiv 355 (1975), S. 361-364 
    Details
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Cs-Ions ; Potassium Channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00579857
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  • 6
    Electronic Resource
    Electronic Resource
    Propriétés des esters d'énols I. Polymérisation d'acétoxyalcènes et études diélectriques des polymères obtenus (1978)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 72 (1978), S. 45-55 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polymerization of acetoxy-2 styrene, parachloro acetoxy-2 styrene, paramethyl acetoxy-2 styrene and paranitro acetoxy-2 styrene was carried out by means of free radical initiators or by thermic reaction. The polymers therefrom showed molecular weights of about 200 000. Studies on the thermal behaviour reveal that these polymers do not undergo any change of phase, either vitreous or crystalline. Dielectric experiments show losses of about 10-3 radian; the losses are practically constant within a large scale of temperature and frequency. Over 320°K one notices a relaxation process of small magnitude and the presence of water brings about a marked change in the way the polymer reacts to dielectric treatment.
    Notes: La polymérisation de I'acttoxy-2 styrène, du parachloro acétoxy-2 styrène, du paramb thyl acétoxy-2 styrène et du paranitro acetoxy-2 styrène a été obtenue avec des amorceurs radicalaires ou par voie thermique. Les polymtres obtenus possedent des masses moyennes en nombre atteignant 200000. L'étude du comportement thermique permet d'établir que ces polymtres ne presentent pas de transition de phase, vitreuse ou cristalline. L'étude diklectrique de ces polymtres a été effectue: on releve des pertes de I'ordre de 10-3 radian, pratiquement constantes dans un large domaine de temphture et de fréquence. Au-delà de 320°K on décèle un mkanisme de relaxation de faible amplitude et la presence d'eau modilie sensiblement son comportement diélectrique.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1978.050720104
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  • 7
    Electronic Resource
    Electronic Resource
    New process for the detection of glass transition temperatures of polymers (1984)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 22 (1984), S. 149-152 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1984.130220304
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  • 8
    Electronic Resource
    Electronic Resource
    Behavior and properties of side chain thermotropic liquid crystal polymers (1997)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 48 (1997), S. 47-87 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 38 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1997.010480301
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  • 9
    Electronic Resource
    Electronic Resource
    Nonaqueous diagnostic polymers and coatings (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 2083-2091 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Water-borne enzymatic coating-based dry chemistries have been used for more than 20 years, especially by diabetics, for self-monitoring of blood glucose. Until now, it has been believed that enzymes work only in water and not in organic solvents. Synthesis of a hydroxylated acrylic polymer and the novel concept of dispersing enzymes have enabled us to design nonaqueous diagnostic coatings. These coating films gave excellent dose response and dynamic range. Additionally, these coatings can easily be ranged by a wide variety of antioxidants. In contrast, water-borne coatings are extremely difficult to range. Furthermore, nonaqueous coating films produce color signals that are independent of the reaction time with excellent thermal stability. Molecular forces and thermodynamical considerations have been used to explain the performance of the new dry chemistries. An organic reaction mechanism of ranging has also been proposed for the nonaqueous system. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070471201
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  • 10
    Electronic Resource
    Electronic Resource
    Small-angle scattering of polarized light. VI. Sphere doublets at rest and during shear (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2005-2013 
    Details
    ISSN: 0887-6266
    Keywords: sphere doublets ; light scattering ; suspension ; flow ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polarized or depolarized light scattering by well-defined monodispersed sphere doublets is investigated. Two configurations of doublets are studied. In the first (at rest) the doublets are randomly oriented in a plane, in the second the doublets are oriented in a preferred direction. This is achieved by submitting a suspension of doublets to a shear flow. The scattering patterns are compared to two theoretical predictions based on simplified geometries. In the first approach, the doublet is approximated by two interpenetrating spheres scattering independently, whereas in the second, an ellipsoid geometry is used. A good qualitative comparison is obtained. However, the HV and VH patterns of a randomly dispersed suspension are not similar. The observation of the flow of a doublet suspension in shear shows that the doublets are spiraling around the vorticity axis. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2005-2013, 1998
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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