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  • 1
    Electronic Resource
    Electronic Resource
    The freshwater snail Bulinus tropicus (Planorbidae) in Namibia, characterised according to chromosome number, enzymes and morphology (1996)
    Springer
    Hydrobiologia 317 (1996), S. 127-139 
    Details
    ISSN: 1573-5117
    Keywords: Mollusca ; Bulinus ; freshwater snails ; taxonomy ; distribution ; Africa ; Namibia ; Schistosoma haematobium ; schistosomiasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Freshwater snails collected in central Namibia, south-western Africa, from 15 populations belonging to the Bulinus truncatus/tropicus complex (Planorbidae) are characterised in respect of their chromosome number, morphology, egg proteins and enzymes. The population samples were all consistently diploid and euphallic. The findings are compared with observations on this group of snails in other areas of Africa. It is concluded that the Namibian populations belong to a single species, B. tropicus (Krauss, 1848), of which B. parietalis (Mousson, 1887) is probably a synonym. No evidence was found of any occurrence of the tetraploid species B. truncatus or of snails belonging to the B. africanus group; lack of a potential intermediate host therefore precludes transmission of Schistosoma haematobium in this area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018736
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  • 2
    Electronic Resource
    Electronic Resource
    Aquatic snails of the Bulinus africanus group in Zambia identified according to morphometry and enzymes (1996)
    Springer
    Hydrobiologia 324 (1996), S. 163-177 
    Details
    ISSN: 1573-5117
    Keywords: Mollusca ; Bulinus ; freshwater snails ; taxonomy ; distribution ; Africa ; Zambia ; Schistosoma haematobium ; schistosomiasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Bulinus africanus species group (Planorbidae) of freshwater snails has been reported to be represented in Zambia by two species, B. africanus (Krauss) and B. globosus (Morelet), both named as intermediate hosts for Schistosoma haematobium. Uncertainty in identification of these snails from morphology led to the present investigation, combining morphometry (shell and copulatory organ) with enzyme analysis. Observations of both kinds were made usually on the same individual snails, from collecting sites mostly in the Lusaka area or at Lake Kariba. Particular attention was given to the proportional relationship between the penis sheath and the preputium of the copulatory organ, a character used previously to distinguish B. africanus from B. globosus in south-eastern Africa. The enzyme profile MDH-1, AcP-2, PGD-1 and PGM-2 was common to all snails examined from 25 populations; GPI and HBDH were polymorphic. The enzyme data indicate that the samples represent a single species. Shell characters varied continuously. The copulatory organ was generally of the form known for B. globosus. Although the copulatory organ of a few individuals had proportions overlapping the range reported for B. africanus, the present variation was continuous and was not bimodal. It is concluded that all these specimens are conspecific and may be identified as B. globosus. Previous identifications of B. africanus from Zambia appear to need substantiation and it seems that if this species is present at all in the sampled areas, it must be uncommon. It is relevant in regard to possible strain differences within S. haematobium in Zambia, that our observations indicate that only a single species of intermediate host is involved in transmission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018178
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  • 3
    Electronic Resource
    Electronic Resource
    Freshwater snails of São Tomé, with special reference to Bulinus forskalii (Ehrenberg), host of Schistosoma intercalatum (1991)
    Springer
    Hydrobiologia 209 (1991), S. 141-153 
    Details
    ISSN: 1573-5117
    Keywords: Bulinus ; Schistosoma intercalatum ; Africa ; São Tomé ; taxonomy ; schistosomiasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract São Tomé Island has 3 known taxa of freshwater gastropod, here identified to species for the first time; Neritina afra Sowerby, Ferrissia eburnensis Binder and a distinctive form of Bulinus forskalii (Ehrenberg). The Bulinus acts as intermediate host for the parasite Schistosoma intercalatum Fisher, the cause of human schistosomiasis in foci of infection detected in recent years on São Tomé. A morphological characterization of this snail is presented, in respect of the shell, radula and copulatory organ. It is compared with B. forskalii populations sampled on the African mainland (Nigeria, Cameroon, Gabon and Angola) and with related taxa. Despite differences in the shell from the commonly found form of B. forskalii it seems appropriate to identify the São Tomé population as an extreme conchological variant of this taxon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00006926
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Specific inhibition of epidermal growth factor receptor tyrosine kinase by 4-anilinoquinazolines (1996)
    Springer
    Breast cancer research and treatment 38 (1996), S. 67-73 
    Details
    ISSN: 1573-7217
    Keywords: epidermal growth factor ; EGF receptor ; quinazolines ; IGF-I ; TGFα ; tyrosine kinase inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Since the mitogenic action of EGF is mediated by ligand-induced autophosphorylation of the EGF receptor (EGFR), and EGFR is commonly overexpressed in solid human tumours, inhibitors of receptor tyrosine kinase activity (RTK) could prove to be effective antitumour agents. Screening of a compound library using an EGF-RTK enzyme prepared from human tumour derived A431 cells identified a series of potent (IC50〈1µM) enzyme inhibitors. These inhibitors are quinazolines bearing a variety of substituted anilines at the 4-position. The most potent 4-anilinoquinazolines (IC50 ≅ 20nM) have small non-polar meta substituents on the aniline ring, and are competitive with ATP and non-competitive with substrate. The growth inhibitory activity of these agents was assessed in vitro using KB cells (human oral squamous tumour) grown in the absence or presence of EGF. A selected compound, 4-(3-chloroanilino)quinazoline (CAQ), inhibited EGF-stimulated growth in a concentration dependent manner and complete blockade was observed at concentrations (1–10 µM) which had no effect on basal growth. Selectivity of growth inhibition by CAQ was further exemplified in IGF1-stimulated KB cells where no effect was detected at concentrations which completely blocked EGF-stimulated growth. Similarly, CAQ blocked TGFα-stimulated growth in MCF-7 human breast cancer cells without affecting insulin-stimulated growth. These studies define a novel class of EGF-RTK inhibitors which are also potent and selective inhibitors of EGF-stimulated human tumour cell growthin vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01803785
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    Paper (German National Licenses)
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