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  • 1980-1984  (4)
  • 1960-1964
  • 1983  (4)
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  • 1980-1984  (4)
  • 1960-1964
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Action and binding of palytoxin, as studied with brain membranes (1983)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 323 (1983), S. 269-275 
    Details
    ISSN: 1432-1912
    Keywords: Palytoxin ; Tetraphenylphosphonium ; Depolarization ; Binding ; Borate ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Palytoxin in concentrations as low as 10−11 to 10−12 M promotes the outflow of the lipophilic [3H]-tetraphenylphosphonium ion from particulate brain cortex of guinea-pigs and rats, and from preloaded crude synaptosomes of rats, which indicates depolarization. The outflow is not influenced by tetrodotoxin or the calcium channel blocker nimodipin, or by substitution of choline for Na+ ions. It is increased by Ca2+ and by borate, the latter interacting with the toxin itself. To assess the fixation of palytoxin to biological membranes, a binding step was installed before the depolarization step. Palytoxin binds to membranes from rat brain, liver, kidney, human and dog erythrocytes, and to a lesser degree to liposomes made from rat brain or erythrocyte lipids. Binding is reversible. It is decreased by mild physical pretreatments of crude synaptosomes. Palytoxin binding is increased in the presence of micromolar concentrations of Ca2+ or borate. It is concluded that the potentiation of palytoxin actions by Ca2+ or borate is at least partially due to the promotion of its binding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00497673
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Lead and other metals can substitute for Ca2+ in calmodulin (1983)
    Springer
    Archives of toxicology 54 (1983), S. 61-70 
    Details
    ISSN: 1432-0738
    Keywords: Calmodulin ; Ca2+ ; Pb2+ ; Phosphodiesterase ; Phosphorylation ; Brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have studied the interaction between some heavy metal ions, as compared with earth alkali ions, and calmodulin, a tissue protein which binds Ca2+ and mediates some of its effects. 1. Calmodulin dependent phosphodiesterase was activated with Pb2+, Ca2+, Sr2+, Ba2+, and Cd2+ (EC50 about 0.8 μM). The maximal activation achieved decreases in the order given. Hg2+ Sn2+, Fe2+, Cu2+, Ni2+, Bi3+, and Sb3+ up to 20 μM did not activate. 2. Pb2+ can replace Ca2+ with respect to the calmodulin-dependent phosphorylation of brain membranes. With high Pb2+ concentrations, phosphorylation was inhibited. 3. Calmodulin binding to brain membranes was enhanced with concentrations below 10−4 M in the following order: Pb2+ ≧Ca2+ ∼ Sr2+ 〉 Cd2+ 〉 Mn2+ 〉 Ba2+. In contrast Mg2+, Hg2+, Sn2+, Fe2+, Ni2+, Co2+, and Cu2+ triggered, if at all, a non-saturable binding of calmodulin. 4. In the flow-dialysis, other ions competed with 45Ca2+ binding to calmodulin in the following order: Pb2+ ∼ Ca2+ 〉 Mn2+, Ba2+, Cd2+, Sr2+. Thus among the ions investigated Pb2+ is a fully potent substitute for Ca2+ in every calmodulin-dependent reaction investigated. Cd2+ is always much less potent. The earth alkali ions Sr2+ and Ba2+ take an intermediate position. It remains to be shown whether calmodulin is merely a storage site for Pb2+, or whether the resulting functional changes play a role in Pb2+ poisoning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00277816
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Monoclonal antibodies against tetanus toxin and toxoid (1983)
    Springer
    Medical microbiology and immunology 172 (1983), S. 123-135 
    Details
    ISSN: 1432-1831
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Monoclonal antibodies against tetanus toxin and its toxoid were produced by immunizing mice with toxoid or toxin. They were measured by an enzyme-linked immunosorbent assay (ELISA), by a toxin neutralization test in mice (in vivo prevention test), and by their ability to prevent binding of125I-toxin to brain membranes or gangliosides (in vitro prevention test). Six monoclonal antibodies obtained by immunization with toxoid (anti-toxoid 1–6) were investigated in more detail. They belonged to IgG class 1. Three of them (anti-toxoid 1, 2 and 3) recognized both toxoid and toxin as well as fragment B and the light chain of toxin, but not fragment C. Two other antibodies (anti-toxoid 4 and 5) were directed against toxoid only. Neither of them prevented toxin action in vitro or in vivo. Anti-toxoid 6 recognized toxin, toxoid and fragment C, but not light chain, and prevented toxin action in vitro and in vivo. Immunization against toxin was initiated with a toxin-antitoxin complex and boosted with toxin. We studied six antibodies in more detail, all of IgG type 2. Their KD against125I-tetanus toxin varied from 10−9 to 10−10 M. Anti-toxin 2 recognized toxin, toxoid, light chain and fragment B, but not fragment C. The others reacted with toxin, toxoid and fragment C, but not with light chain or fragment B. All of them prevented toxin action in vitro and in vivo. As calculated from the maximal extinction achieved in the ELISA, tetanus toxin combined with a maximum of two different antibody molecules from our set. Gel filtration data indicate that tetanus toxin reacts with monoclonal antibodies one by one. Compared with polyclonal antiserum, monoclonal antibodies yield flatter slopes in both in vitro and in vivo prevention tests. Thus, they cannot substitute for the polyclonal antibodies in clinical situations, and cannot be calibrated in international units.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02124513
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The action of palytoxin on erythrocytes and resealed ghosts (1983)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 323 (1983), S. 261-268 
    Details
    ISSN: 1432-1912
    Keywords: Palytoxin ; Erythrocyte ; Membrane ; Na+, K+-ATPase ; Calcium ; Ouabain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Palytoxin increases the permeability of human erythrocytes and their resealed ghosts. To elucidate its mode of action the activation by ATP and Ca2+, the inhibition by ouabain, and the changes in permselectivity have been studied: 1. Depletion of cells from ATP considerably depresses their sensitivity towards palytoxin. Ouabain prevents the actions of the toxin, however, with different inhibition characteristics in normal and depleted cells. The concentration of palytoxin required to raise the K+ permeability is higher in ghosts than in erythrocytes. The sensitivity is restored by incorporating ATP which can be partially substituted by ADP and GTP but not by AMP, Pi, β-γ-methylene adenosine 5′-triphosphate or the chromium (III) complex of ATP. Ouabain inhibits the K+ release from resealed ghosts in the presence as well as absence of ATP. Ouabain also inhibits the palytoxin-triggered Na+ and choline efflux into Na+ medium, as well as the Na+, K+ and choline efflux into choline medium. Phosphate promotes the inhibitory action of ouabain. Incorporated vanadate or Mg2+ do not change the sensitivity of ghosts toward palytoxin. 2. External calcium down to 10 μM potentiates the action of palytoxin in ghosts resealed with or without ATP. In contrast to calcium ionophore A23187, palytoxin does not raise the influx of Ca2+. 3. Palytoxin triggers the formation of small pores in resealed ghosts. The efflux into Na+ medium decreases in the order K+≧Na+〉[3H]choline≫[14C]inositol〉[14C]sucrose, [3H]inulin≅0. Our data suggest that palytoxin, once bound to erythrocyte membranes, transforms the sodium pump, or its functional vicinity, into a pore allowing the passive transport of small ions. This process is assisted by ATP from inside whereas Ca2+ promotes from the outside the efficacy of palytoxin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00497672
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    Paper (German National Licenses)
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