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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 63 (1985), S. 90-92 
    ISSN: 1432-1440
    Keywords: Nicotine and metabolites ; Dose-response curves ; Blood pressure ; Heart rate ; Anaesthetized rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Blood pressure and heart rate in anaesthetized rats has been determined after i.v. injection of increasing doses of nicotine (NI) and its major metabolites, i.e. continine (CO), nornicotine (NOR), metanicotine (MN) and dihydrometanicotine (DMN). NI and MN elicited similar dose response curves, increasing blood pressure according to the dose injected. However, the dose response curve of MN was shifted to the right. Furthermore DMN caused similar pressor effects than MN and the pressor effects of NOR was even weaker. Only after injection of CO was a dose-dependent depressor effect observed and this was reversed after very high doses. CO also reduced heart rate in a dose-dependent manner, whereas NI and its other metabolites did not significantly change heart rate.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 61 (1989), S. 463-466 
    ISSN: 1432-1246
    Keywords: Shift work ; Night shift ; Blood pressure ; 24-h blood pressure monitoring ; Circadian rhythm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The dependence of blood pressure upon internal rhythms and the short-term effects of shift rota on the blood pressure were investigated in shift workers. Blood pressure was measured every 30 min using automatic recorders for 24 h in 17 physically working men in a chemical factory during their morning and night shifts. Mean 24-h blood pressures were identical in the morning and night shifts. There were no differences of the mean blood pressure between the respective sleeping phases or between the working periods. The amplitudes of circadian blood pressure variations were equal. There was a phase difference of 8 h corresponding to the lag between the working periods. At this 8-h lag the hourly means of the 24-h blood pressure were closely correlated (r = 0.69). Comparisons of 24-h blood pressure profiles during the first and last days of a night shift week showed that the effects of night work on the blood pressure were already fully developed within the first 24h (r = 0.86). Thus the diurnal variations of the blood pressure are determined by the working and sleeping periods and largely independent of endogenous rhythm. There is no short-term alteration of the mean 24-h blood pressure after shift rota.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: ATP-citrate lyase ; Citric acid cycle ; Acetate oxidation ; ATP synthesis via substrate level phosphorylation ; Sulfate-reducing bacteria ; Desulfobacter postgatei
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Desulfobacter postgatei is an acetate-oxidizing, sulfate-reducing bacterium that metabolizes acetate via the citric acid cycle. The organism has been reported to contain a si-citrate synthase (EC 4.1.3.7) which is activated by AMP and inorganic phosphate. It is show now, that the enzyme mediating citrate formation is an ATP-citrate lyase (EC 4.1.3.8) rather than a citrate synthase. Cell extracts (160,000xg supernatant) catalyzed the conversion of oxaloacetate (apparent K m=0.2 mM), acetyl-CoA (app. K m=0.1 mM), ADP (app. K m=0.06 mM) and phosphate (app. K m=0.7 mM) to citrate, CoA and ATP with a specific activity of 0.3 μmol·min-1·mg-1 protein. Per mol citrate formed 1 mol of ATP was generated. Cleavage of citrate (app. K m=0.05 mM; V max=1.2 μmol · min-1 · mg-1 protein) was dependent on ATP (app. K m=0.4 mM) and CoA (app. K m=0.05 mM) and yielded oxaloacetate, acetyl-CoA, ADP, and phosphate as products in a stoichiometry of citrate:CoA:oxaloacetate:ADP=1:1:1:1. The use of an ATP-citrate lyase in the citric acid cycle enables D. postgatei to couple the oxidation of acetate to 2 CO2 with the net synthesis of ATP via substrate level phosphorylation.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-072X
    Keywords: Desulfobacter hydrogenophilus ; Sulfate-reducing bacteria ; Autotrophy ; Citric acid cycle ; ATP-citrate lyase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The strict anaerobe Desulfobacter hydrogenophilus is able to grow autotrophically with CO2, H2, and sulfate as sole carbon and energy sources. The generation time at 30°C under autotrophic conditions in a pure mineral medium was 15 h, the growth yield was 8 g cell dry mass per mol sulfate reduced to H2S. Enzymes of the autotrophic CO2 assimilation pathway were investigated. Key enzymes of the Calvin cycle and of the acetyl CoA pathway could not be found. All enzymes of a reductive citric acid cycle were present at specific activities sufficient to account for the observed growth rate. Notably, an ATP-citrate lyase (1.3 μmol · min-1 · mg cell protein-1) was present both in autotrophically and in heterotrophically grown cells, which was rapidly inactivated in the absence of ATP. The data indicate that in D. hydrogenophilus a reductive citric acid cycle is operating in autotrophic CO2 fixation. Since other autotrophic sulfate reducers possess an acetyl CoA pathway for CO2 fixation, two different autotrophic pathways occur in the same physiological group.
    Type of Medium: Electronic Resource
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