Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1970-1974  (3)
  • Node of Ranvier  (2)
  • Antibiotics  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 349 (1974), S. 133-148 
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Sodium Permeability ; Aconitine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of aconitine (10−5–10−6 g/ml) on membrane potentials and membrane currents of myelinated nerve fibres of Xenopus laevis was investigated. The following observations were made: a) Current clamp conditions: Slow depolarization (10–15 mV), decrease of amplitude and maximum rate of rise of action potential, finally inexcitability. With inward current pulses ‘hyperpolarizing responses’ could be elicited at membrane potentials more negative than the resting potential (E r ). Neither spontaneous activity nor repetitive responses to electrical stimuli were observed. No effects of aconitine were found in Na-free solutions or in the presence of tetrodotoxin. b) Voltage clamp conditions: Development of steady inward current at normal resting potential due to formation of a non-inactivating sodium permeability; heavily poisoned nodes therefore exhibit an N-shaped steady-state current voltage relation with negative slope at membrane potentials more negative thanE r . These non-inactivating sodium channels open more slowly than normal sodium channels, and can only be closed by hyperpolarizing the membrane by about 50 mV. The majority of sodium channels have almost normalτ m; theirm ∞ andh ∞-V relations are shifted by 10–15 mV towardsE r . It is concluded that these changes of the sodium permeability account for the changes of electrical activity observed after treatment with aconitine.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 203 (1972), S. 171-183 
    ISSN: 1432-1459
    Keywords: Brain Abscess ; Contrast Medium Effect on Antibiotic ; Steripaque ; Antibiotics ; Contrast Medium Effect ; Hirnabsceß
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die moderne Behandlung der Hirnabscesse beruht auf einer Absceßpunktion mit Entleerung des Eiters und nachfolgender Instillation eines Antibioticums und eines Kontrastmittels. Nach mehrfachen Punktionen kann die kleine, nunmehr sterile Absceßkapsel excidiert werden. Zur Darstellung dieser Kapsel kamen bisher zahlreiche Substanzen zur Anwendung. Sowohl Luft als auch positive Kontrastmittel besitzen Vor- und Nachteile, die im einzelnen diskutiert werden. Das Behandlungsziel liegt in der Exstirpation der sterilen Absceßkapsel. Es erhebt sich daher die Frage, ob das Kontrastmittel die Wirksamkeit des Antibioticums nachteilig beeinflußt. Aus den zur Klärung dieses Problems durchgeführten klinischen und bakteriologischen Untersuchungen ergibt sich, daß das Antibioticum Nebacetin von den heute gebräuchlichen Kontrastmitteln in seiner Wirkung nicht beeinträchtigt wird.
    Notes: Summary Modern treatment of brain abscesses is based on the aspiration of pus through a burr-hole, the instillation of an antibiotic and a contrast medium and later, the excision of the shrunken sterile abscess. Various contrast media have been used for direct radiological demonstration of abscesses. Beginning with thorotrast, the advantages and disadvantages of air and radiopaque substances including iodine esters such as Duroliopaque, water-soluble Dimer-X and barium sulfate are discussed. Steripaque (barium sulfate in sterile form) has proved particularly useful in outlining the wall of the abscess. Since the object of the aspiration treatment is sterilization of the abscess, it is necessary to consider whether the contrast medium affects the action of the antibiotic. The clinical results of 30 selected patients show no significant differences, the interactions of the antibiotic with the various contrast media are illustrated by means of bacteriological in vitro investigations.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 333 (1972), S. 51-61 
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Ionic Currents ; Scorpion Venom ; Calcium Ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Voltage clamp experiments were done on myelinated nerve fibres of Xenopus laevis to study the effect of calcium on the ionic currents of the nodal membrane treated with scorpion venom. Increasing the calcium concentration of the medium from 1.8 to 7.2 mM produced the following changes of the sodium and potassium permeabilities,P Na andP K: a) The incomplete sodium inactivation, which is typical for nodes of Ranvier treated with scorpion venom, is abolished. The curves relatingm ∞ and τ m to membrane potential are shifted by 8–10 mV towards larger depolarizations.P Na and the time constants of the fast and slow components of the sodium inactivation remain practically unchanged. b) The maximum potassium permeability,P K, which is reduced by scorpion venom to 45% of the value observed in the normal node, increases to 68% by addition of calcium ions; τ n is unchanged. These effects of calcium ions on the ionic permeabilities explain the shortening of the extremely prolonged action potential and the inhibition of spontaneous activity observed in nodes of Ranvier poisoned with scorpion venom.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...