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  • 1985-1989  (3)
  • 1905-1909
  • 1989  (3)
  • Allelopathy  (1)
  • Delayed ethanol effect  (1)
  • right atrium  (1)
  • Analytical Chemistry and Spectroscopy
  • General Chemistry
  • allelochemical
Material
Years
  • 1985-1989  (3)
  • 1905-1909
Year
Keywords
  • 1
    ISSN: 1432-2072
    Keywords: Ethanol ; Tolerance ; Operant performance ; Delayed ethanol effect ; Drug-induced compensatory learning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of pre-session and post-session daily ethanol injections on the development and loss of tolerance to ethanol's effects on fixed ratio operant performance in rats was assessed using a cumulative dosing procedure. Daily pre-session ethanol administration produced a greater decrease in ethanol sensitivity than did daily post-session ethanol. Both tolerance effects persisted for at least 1 month after the chronic injection phase. No changes in ethanol sensitivity were apparent in the saline control group and no changes in estimated blood ethanol levels were found after the chronic treatments. The post-session ethanol groups displayed a performance decrement during the initial segment of the chronic injection period, but improved significantly across the chronic phase. These data suggest that some delayed effect of ethanol initially impaired performance but that tolerance to this ethanol effect also occurred and probably contributed to the decline in ethanol sensitivity seen in these groups. Compensatory learning as the mechanism for tolerance development in the pre-session and post-session ethanol groups was supported by the finding of no change in ethanol sensitivity in rats exposed to comparable daily ethanol without any concurrent operant task on which the direct, immediate, or indirect, delayed ethanol effects could operate.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-0743
    Keywords: right atrium ; atrial volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Until now, right atrial (RA) volume calculation by means of two-dimensional echocardiography (2-DE) has only been attempted in a single plane: the apical four-chamber view. Our study reports a new method for RA volume calculation using two intersecting 2-DE views. For this purpose, silicone rubber casts of 19 human necropsy hearts were obtained and thin-walled natural rubber moulds of the RA casts were prepared. Totally filled with and immersed in water, the moulds could be visualized in the apical four-chamber view and an additional 2-DE plane, the latter corresponding to the subcostal view in vivo. In this view the vertical extension of RA could be estimated. Areas and lengths of RA were determined in the respective planes, and RA volume was calculated by applying the formula, area x length, to two intersecting planes. Finally, volume of the silicone casts was determined angiocardiographically (Angio) using a biplane method (30° RAO, 40° LAO-40° hepatoclavicular). The true RA volume was 106±23 ml (mean±1SD) as determined by water displacement. Using Angio an excellent correlation was found: the calculated volume amounted to 106±23ml; the difference was 5.5±4.8ml (n.s.); Angio vol=0.93 true vol+ 7.77; r=0.95; SEE= 7,4 ml. Volume determination from the apical four-chamber view of 2-DE using a monoplane disk method resulted in a mean volume of 62±17 ml. The mean difference to the true RA volume was 44±16 ml (p 〈 0.001). When volume calculations were made using the biplane method, a value of 105±22 ml resulted. The mean difference to true volumes was 7.4±4.8 ml: y=0.84x + 15.88; r=0.91; SEE=9.4 ml. In an in vivo study endsystolic RA volumes were calculated in a normal adult population (n=40) from the same intersecting planes as in vitro. A normal value of 38±6 ml/m2 was found. In vivo validation using Angio showed a slightly higher normal value of 43=7 ml/m2. Thus, 2-DE is highly accurate in determinating RA volume. In the in vitro as well as in the in vivo study the results of monoplane calculations are clearly inferior to a method which also takes account of the vertical extension of RA.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 15 (1989), S. 951-960 
    ISSN: 1573-1561
    Keywords: Allelopathy ; grain sorghum ; Sorghum bicolor ; weed inhibition ; weed management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Three years of field data in northeastern Nebraska demonstrate that a grain sorghum crop reduces weediness in the following crop year. Weed growth was consistently lower in sorghum areas the year after strip-cropping fields with sequences of four-row bands of grain sorghum, soybeans, and corn. Percentage weed cover was significantly lower early in the year, and midsummer weed biomass was well below that found after corn and soybeans. Weed biomass in June and July following corn was two to four times that of grain sorghum strips. Inhibitory effects of grain sorghum were primarily on broadleaf weeds, often showing no action on grass weeds. No obvious differences were noted in the weed species present after the three crops. Allelopathy provides a logical explanation for the sorghum-mediated weed inhibition found in this study. The data have implications for weed management strategies in agriculture.
    Type of Medium: Electronic Resource
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