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  • Benign osteochondromas  (1)
  • Cholinergic neurons  (1)
  • 1975-1979  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 132 (1979), S. 271-276 
    ISSN: 1432-1076
    Keywords: Exostoses ; Benign osteochondromas ; Bone tumors ; Radiation therapy ; Radium-224 ; Thorium X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Exostoses are benign cartilaginous tumors of bone. They can occur naturally or be induced by radiation therapy during the time of skeletal growth. We have observed exostoses in 28 of 218 children given repeated injections of radioactive bone-seeking 224Ra. The younger the age at irradiation, the higher the incidence of exostoses. Boys are more susceptible than girls. To our knowledge, none of these radiation-induced exostoses have become malignant, although 36 of these children have developed bone sarcomas elsewhere in the skeleton.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1912
    Keywords: p-Nitrophenyl diazonium fluoroborate ; Cholinergic neurons ; Acetylcholine receptor ; Acetylcholinesterase ; Affinity labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Electrophysiological experiments were done to investigate the effect of p-nitrophenyl diazonium fluoroborate (p-NPD) on motor endplates of the frog's m. cutaneus pectoris. The compound has no direct depolarizing effect on the postsynaptic membrane and stabilizes it irreversibly when added to the bath. Longtime iontophoretical applications of p-NPD produce a biphasic effect: initially a potentiation of the depolarizations due to acetylcholine (ACh) (both iontophoretically applied and presynaptically liberated), and subsequently an inhibition of the response to ACh. When the acetylcholinesterase (AChE) is inactivated previously, only the inhibiting effect of the compound is demonstrable. The association constant of p-NPD to purified AChE and to membrane fragments of electroplax was determined by biochemical methods. The compound's affinity to the AChE was found to be about 20 times greater than to the acetylcholine receptor (AChR). Iontophoretical application of p-NPD to cholinergic neurons in the hippocampal cortex of the cat also produced the characteristic biphasic effect on ACh-induced activity of these investigated neurons. The results suggest that the biphasic effect depends on the capacity of p-NPD to combine with both the AChE and the AChR. The AChE is first inhibited with low concentrations thereby potentiating the ACh response. At higher concentrations the AChR's are progressively inhibited too, thereby diminishing the excitability of the postsynaptic membrane up to a complete block.
    Type of Medium: Electronic Resource
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