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  • 1995  (6)
  • 1
    Language: English
    In: SIL Proceedings, 1922-2010, 01/1995, Vol.26(3), pp.1271-1276
    Description: .
    Keywords: Insecticides ; Sublethal Effects ; Population Dynamics ; Zoobenthos ; Agricultural Runoff ; Gammarus Pulex ; Limnephilus Lunatus ; Germany, Niedersachsen, Ohebach ; Freshwater ; Benthos ; Effects on Organisms;
    ISBN: 3510540476
    ISSN: 0368-0770
    Source: Informa - Taylor & Francis (via CrossRef)
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  • 2
    Language: English
    In: Hydrobiologia, 1995, Vol.299(2), pp.103-113
    Description: The insecticide load in surface waters does not ordinarily reach concentrations acutely toxic to aquatic fauna. The effects of the low insecticide concentrations typical of natural habitats are still not clear, for they often appear only after relatively long exposure times. To test such a situation, the insecticides lindane and parathion were introduced into a static-with-renewal outdoor aquaria system at concentrations about four and five orders of magnitude lower than their respective 96-h LC 50 s, and their chronic (about 90 days) effects on the survival rate of freshwater caddisfly larvae were observed. The emergence and hence survival rate of Limnephilus lunatus Curtis was significantly reduced by lindane at 0.1 ng l −1 , a value nearly five orders of magnitude lower than the 96-h LC 50 . Parathion, with acute and subacute toxicity similar to that of lindane, did not significantly alter the emergence rate of this species. In contrast, this substance did produce a significant reduction in emergence rate of the closely related species Limnephilus bipunctatus Curtis at 1 ng l −1 , even though this species was significantly less susceptible than L. lunatus to parathion at high concentrations. We conclude that chronic insecticide exposure can be hazardous to freshwater macroinvertebrates even at unexpectedly low concentrations. The low-concentration effects may depend on both species and substance and therefore cannot be predicted from toxicity data at higher concentrations.
    Keywords: chronic toxicity ; emergence ; low-level pollution ; lindane ; parathion ; Trichoptera
    ISSN: 0018-8158
    E-ISSN: 1573-5117
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  • 3
    Language: German
    Description: Mikrofiche-Ausg.: 2 Mikrofiches : 24x ; Thesis (doctoral)--Technische Universität Berlin, 1994 ; 157 Bl. : graph. Darst
    Keywords: Gestein -- Deformation -- Elastische Spannung -- Wellenausbreitung -- Nichtlineare Elastizitätstheorie
    Source: Center for Research Libraries
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  • 4
    Language: English
    In: FEMS Microbiology Ecology, 1995, Vol.16(4), pp.251-259
    Description: In the profundal sediment of Lake Constance (143 m depth) the temperature is constant at 4 degree C. Despite the constant temperature, CH sub(4) concentrations changed with season between about 120 mu M in winter and about 750 mu M in summer, measured down to 30 cm depth. The acetate concentration profiles also varied between seasons. In summer, acetate concentration reached a maximum at about 100 mu M in 2 or 4 cm depth. In winter, maximal concentrations of about 5 mu M were observed over the entire depth. Input of organic material in late spring may be the reason for the seasonal change of both compounds. To simulate such a sedimentation event, intact sediment cores were covered with suspensions of Porphyridium aerugenium or Synechococcus sp. The addition of the phytoplankton material resulted in a drastic increase of acetate concentrations with a maximum at 2 cm depth, similar to in situ acetate concentrations measured in summer. The same applies for CH sub(4) for which increased concentrations were observed down to 6 cm depth. H sub(2) concentrations, on the other hand, showed no distinct increase. Treatment of intact sediment cores with super(14)C-labeled Synechococcus cells resulted in the formation of super(14)C-acetate, super(14)CH sub(4) and super(14)CO sub(2). Maximum concentrations of super(14)CH sub(4) were found at 4 cm depth, i.e. just above the depth to which super(14)C-acetate penetrated. The results show that phytoplankton blooms may cause a seasonal variation of acetate and CH sub(4) in profundal sediments of deep lakes despite the constant low temperature. They also indicate that acetate is the dominant substrate for methanogenic bacteria in the profundal sediments of Lake Constance.
    Keywords: Methane ; Acetate ; Concentration Profile ; Profundal Sediment ; Sedimentation ; Seasonal Change ; Environmental Sciences ; Biology
    ISSN: 0168-6496
    E-ISSN: 1574-6941
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  • 5
    Language: English
    In: Journal of Fluorine Chemistry, 1995, Vol.74(2), pp.185-189
    Description: Side-group liquid-crystalline polymers with fluorine-containing mesogens were synthesized and characterized. 4-Trifluoromethoxy-aniline was diazotized and coupled with phenol to give 4-hydroxy-4′-trifluoromethoxy-azobenzene. Alkylation of this compound with α,ω-dibro-moalkanes, followed by reaction with the potassium salts of acrylic or methacrylic acid, yielded the monomers. Their radical polymerization gave the corresponding polyacrylates or polymethacrylates, respectively. The polymers were characterized by size exclusion chromatography (SEC) and by differential scanning calorimetry (DSC).
    Keywords: Liquid Crystal Polymer ; 4-Trifluoromethoxy-Azobenzene ; Polyacrylates ; Polymethacrylates ; Chemistry
    ISSN: 0022-1139
    E-ISSN: 1873-3328
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  • 6
    Language: English
    In: Biochemical Pharmacology, 1995, Vol.50(9), pp.1517-1520
    Description: The induction of cytochrome P450 by enoxacin, ciprofloxacin, and ofloxacin was investigated in female Wistar rats. Animals were treated orally with daily doses ranging from 10 to 400 mg enoxacin per kg body wt, 400 mg ciprofloxacin, or 400 mg ofloxacin per kg body wt for up to 7 days. Activities of methoxyresorufin O-demethylase (MROD) and ethoxyresorufin O-deethylase (EROD) were determined fluorimetrically in hepatic microsomes. MROD activity was increased 2.6-fold after treatment with 100 mg enoxacin per kg body wt for 7 days. Lower doses of enoxacin did not induce MROD activity significantly. Antipeptide antibodies directed specifically against different rat cytochrome P450 enzymes demonstrated that CYP1A2, but not CYP1 A1, was induced in rats treated with enoxacin. After ciprofloxacin or ofloxacin treatment, no induction of MROD or EROD activity was observed. Neither ciprofloxacin nor ofloxacin caused any change in CYP1A1 or CYP1A2 apoprotein levels. Further investigations with antipeptide antibodies showed that there was no induction of CYP2B1, CYP2B2, CYP2E1, CYP3A1, CYP3A2, CYP4A1, or CYP4A2 following treatment with enoxacin, ciprofloxacin, or ofloxacin. It is concluded that enoxacin, but not ciprofloxacin or ofloxacin, is an inducer of CYP1A2 in rat liver.
    Keywords: Quinolones ; Induction ; Cyp1a2 ; Ethoxyresorufin ; Methoxyresorufin ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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