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  • Articles: DFG German National Licenses  (2)
  • 2000-2004  (1)
  • 1990-1994  (1)
  • [3H]Tamsulosin  (1)
  • sclerotium  (1)
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  • Articles: DFG German National Licenses  (2)
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  • 2000-2004  (1)
  • 1990-1994  (1)
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  • 1
    ISSN: 1434-0879
    Keywords: [3H]Tamsulosin ; Radioreceptor assay ; Human prostates ; α1-antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The binding of a novel radioligand, [3H]tamsulosin, to human prostatic membranes with benign prostatic hypertrophy (BPH) has been characterized. [3H]Tamsulosin rapidly associated with its binding sites in human prostatic membranes with BPH, and the binding reached steady state by 30 min at 25°C. The rate constants for association and dissociation of [3H]tamsulosin binding were calculated to be 0.21±0.05/nM per minute and 0.01±0.004/min, respectively. The specific binding of [3H]tamsulosin in human prostatic membranes was saturable and of high affinity (K d=0.04±0.01 nM). The density of [3H]tamsulosin-binding sites (B max) was 409±28 fmol/mg protein. The K d and B max values for [3H]tamsulosin binding in human prostates were significantly lower than those for [3H]prazosin binding. [3H]tamsulosin binding was remarkable for its significantly lower degree of nonspecific binding. Six α-adrenoceptor antagonists competed with [3H]tamsulosin for the binding sites in the rank order: tamsulosin〉WB4101〉prazosin〉S-(+)-isomer〉naftopidil〉yohimbine. The binding affinities (pKi) of these antagonists for [3H]tamsulosin binding in human prostates closely correlated with their pharmacological potencies (pA2) in prostates. In conclusion, [3H]tamsulosin selectively labels α1-adrenoceptors in human prostates, and thus may become a useful radioligand for the further analysis of these receptors.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Ecological research 15 (2000), S. 405-414 
    ISSN: 1440-1703
    Keywords: egg recognition ; sclerotium ; subterranean termite ; symbiosis ; termite–fungus interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Brown balls, of a similar size but different shape to termite eggs, were found frequently in the piles of eggs of the subterranean termite Reticulitermes speratus. rDNA analysis identified the ball as the sclerotia of the fungus, Fibularhizoctonia sp. nov, which is phylogenetically closest to decay fungi, Athelia spp. Laboratory observation showed that the workers gathered the eggs and the sclerotia indiscriminately, even if they were widely scattered in a Petri dish, and piled them up in a specific place for egg care. We compared the morphology of the eggs with that of sclerotia of Fibularhizoctonia spp. and Athelia spp. in relation to egg carrying behaviour, and found that the workers could only carry the Fibularhizoctonia spp. sclerotia whose diameters were similar to the short diameter of the eggs. We also conducted a bioassay using termite eggs and dummy eggs (glass beads and sea sand) of two diameter-classes, coated with or without the egg-derived chemicals. The workers recognized the eggs based on a combination of the size, shape, and chemical cues. All the results suggested that the sclerotia mimic the eggs both morphologically and chemically. Finally, we found that the workers suppressed germination of sclerotia, and termite egg survival increased in the presence of sclerotia only if they were tended by the workers. If the workers were removed experimentally, the sclerotia germinated and grew by exploiting termite eggs. These results suggest that the sclerotia protect termite eggs from putative pathogens.
    Type of Medium: Electronic Resource
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