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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 290 (1975), S. 221-234 
    ISSN: 1432-1912
    Keywords: Biliary Excretion ; Choleresis ; Nafenopin Enterohepatic Circulation ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Administration of nafenopin (SU-13-437) to male rats for two days leads to a doubling of bile production and a 50% increase in liver weight. These two effects have been shown not to be directly interrelated. A marked decrease in biliary bile salt concentration suggests that the bile salt independent flow is stimulated. The extra bile produced is probably of canalicular origin since bile to plasma concentration ratios of erythritol are unchanged. At least three polar metabolites of nafenopin have been observed in rat bile. Obervations in rats with partial biliary fistulas indicate that the drug and its metabolites undergo extensive enterohepatic circulation. Our studies support the view that much of the enhanced bile flow is associated with the presence of nafenopin and/or its metabolites within the hepatobiliary system. However, the response is too extensive to be explained merely by osmotic choleresis. Induced structural changes in the liver may also account for some of this effect.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 290 (1975), S. 235-250 
    ISSN: 1432-1912
    Keywords: Nafenopin ; Biliary Excretion ; Hepatic Uptake ; Hypolipidemic Agents ; Dibromosulphthalein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rats treated with the hypolipidemic agent, nafenopin (SU-13, 437) exhibit a higher plasma retention and a markedly reduced biliary excretion of organic anions, such as sulfobromophthalein (BSP) and its dibromo analog (DBSP), indocyaninegreen (ICG), succinylsulfathiazole (SST) and polar metabolites of bilirubin and the carcinogens 7, 12-dimethylbenzanthracene (DMBA) and 3,4-benz-pyrene (BP), despite an increase in liver mass and a profound choleresis. However, taurocholate is not affected in this manner, which supports the idea of a transport mechanism for taurocholate that differs from that of other organic anions. A pharmacokinetic study was made for DBSP in vivo. After nafenopin treatment, primary hepatic uptake (k12) and transport from liver into bile (k23) are reduced in vivo. Infusion studies indicate that biliary transport maximum (Tm) for DBSP is also decreased although the calculated hepatic storage (S) is only moderately affected. In the isolated perfused liver, hepatic clearance and biliary excretion of BSP are reduced by two-thirds. The time course of anion tranport inhibition and the hepato-biliary disposition of 14C-nafenopin suggest a direct effect of the drug. The extra liver mass induced by nafenopin appears to be hypo- or nonfunctional with respect to hepatic transport of organic anions.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1939
    Keywords: Biased sex ratios ; Dineura virididorsata ; Sex-related survival ; Local mate competition ; Foliage quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sex ratio in final-instar larvae of a birch-feeding, free-living solitary sawfly, Dineura virididorsata, was investigated in Finnish Lapland. The prepupal proportion of females, pooled over ten sites, was 56%, and at four individual sites the sex ratio was significantly female-biased. Larval survival from egg to prepupae did not differ between the sexes. This suggests a femalebiased primary sex ratio in the field. The sex ratio varied among the sites but not among host trees within sites. Contrary to previous results with hymenopterans, we did not find that differences in the sex ratio depended on forage quality: site-specific or tree-specific sex ratios did not correlate with the average prepupal weight. A literature search indicated that female-biased sex ratios are also common in other free-living sawflies. We are unable to explain sex ratios of Dineura virididorsata or other free-living sawflies with existing general models.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 70 (1994), S. 83-90 
    ISSN: 1570-7458
    Keywords: Hymenoptera ; Symphyta ; Tenthredinidae ; Dineura virididorsata ; sawfly ; sex ratio ; oviposition behaviour ; mating behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sex ratios of the arrhenotokous sawflyDineura virididorsata Retz. (Hymenoptera: Tenthredinidae) are variable among populations in the field, but are biased in favour of females. We have concluded elsewhere that the sex ratios of this species cannot be satisfactorily explained by any general sex ratio model that is available. Here we present data on the different behavioural traits that are relevant to interpretation of the evolution of female-biased sex ratios under local mate competition. We report on oviposition behaviour, mating behaviour and the patterns of movement of ovipositing virgin and mated females. Our results show that adult emergence is synchronous and females will mate daily with different males (in the laboratory, at least). This would decrease the relatedness of offspring should it also take place in the field. In addition, ovipositing females (mated and virgin) leave their site of release in a relatively short time and deposit few eggs relative to their capabilities, so siblings are unlikely to be clumped. The time that virgins spend in deposition of an egg is not different from that spent by mated females, so there is no differential ‘investment’ in this regard. These behavioural observations agree with our previous conclusion that the preconditions of current sex ratio theories are not met byD. virididorsata.
    Type of Medium: Electronic Resource
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