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  • 1
    ISSN: 1432-069X
    Keywords: Glucose-6-phosphate dehydrogenase ; Dehydroepiandrosterone ; Mononuclear leukocytes ; Psoriasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of the study was to determine a biochemical basis for the augmented oxidative metabolism found in mononuclear leukocytes (MNL) of patients with active psoriasis. Dehydroepiandrosterone (DHEA) is known to inhibit glucose-6-phosphate dehydrogenase (G-6-PDH). We determined the activity of G-6-PDH as well as the penetration and metabolism of DHEA — diminished plasma concentrations of which have been found in psoriatics previously — in 16 patients with active psoriasis and 16 controls. MNL in patients with psoriasis possessed 52% more (p〈0.05) G-6-PDH activity, based on cell number, and 34% more (p〈0.05) activity, based on soluble protein. No difference in DHEA penetration and metabolism in MNL was found between psoriatics and controls, in contrast with previous findings of reduced penetration and increased reduction in erythrocytes of psoriatics. We conclude that the enhanced G-6-PDH activity in MNL of patients with active psoriasis is not due to altered DHEA penetration or metabolism.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 266 (1979), S. 181-185 
    ISSN: 1432-069X
    Keywords: Radioimmunoassay ; Dehydroepiandrosterone ; Androstene-diol ; Psoriasis ; Radioimmunologische Bestimmung ; Dehydroepiandrosteron ; Androstendiol ; Psoriasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Mittels radioimmunologischer Bestimmungsverfahren wurden die Steroide Dehydroepiandrosteron und 5-Androsten-3ß,17ß-diol im Plasma von Psoriatikern und Kontrollpersonen bestimmt. Entsprechend den bereits früher mit photometrischen Methoden erhobenen Befunden war bei den Psoriatikern der Plasma-Spiegel des Dehydroepiandrosterons erniedrigt und der des Androstendiols erhöht.
    Notes: Summary In the plasma of psoriatics and controls the steroids dehydroepiandrosterone and 5-androstene-3ß,17ß-diol were determined by radioimmunoassay. Corresponding earlier findings obtained by photometric methods in psoriatics the plasma level of dehydroepiandrosterone is increased and that of androstenediol is decreased.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 270 (1981), S. 49-55 
    ISSN: 1432-069X
    Keywords: Psoriasis ; Dehydroepiandrosterone ; Penetration kinetics ; Erythrocytes ; Psoriasis ; Dehydroepiandrosteron ; Penetrationskinetik ; Erythrocyten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei zehn Kranken mit Psoriasis vulgaris und zehn Kontroll-personen wurde die Penetrationskinetik von freiem Dehydroepiandrosteron (DHEA) durch die Erythrocytenmembran und der Metabolismus des penetrierten DHEA untersucht. Entsprechend früheren Befunden ist die Penetration des DHEA bei Psoriatikern erniedrigt und der intraerythrocytäre Stoffwechsel zugunsten einer verstärkten Reduktion dieses Steroids verschoben. Bei Psoriatikern und Kontrollpersonen ergab sich weiterhin eine lineare Abhängigkeit der Penetration von DHEA in den Erythrocyten von der DHEA-Konzentration im Inkubationsmedium. Dieser Befund weist am ehesten auf eine passive Diffusion dieses Steroids durch die Zellmenbran hin.
    Notes: Summary In ten patients with psorasis and ten controls the penetration kinetics of free dehydroepiandrosterone (DHEA) through the erythrocyte membrane and the metabolism of penetrated DHEA was studied. Corresponding to former findings in psoriatics the penetration of DHEA is decreased and the metabolism in the erythrocyte is shifted to an increased reduction of DHEA. Furthermore, in psoriatics and controls there was a positive correlation between the DHEA penetration through the erythrocyte membrane and the DHEA concentration outside the cell. These data point to a passive diffusion of DHEA.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 741-748 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 301-319 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been shown both theoretically and experimentally that interphase nitrogen transport may have a significant influence on the rate of interphase oxygen transport, and thereby also on the value of the volumetric mass transfer coefficient of oxygen, kla, determined in mechanically agitated bubble fermentors using the variants of dynamic method presented in the literature. The experiments were carried out in 1M KCI solution at five stirrer frequencies and two gas inlet levels. The gas interchanges were performed either without interrupting the aeration and agitation of the charge (A) or with the aeration and agitation of the charge turned on at the same time (B). The applied variants of the interchange were N2→ O2→, O2→ N2, N2→ air, air→ N2, O→ O2, and O→ air. In the two last variants the oxygen dissolved in the charge was removed by reacting with sulfite ions. The kla values calculated by allowing for the nitrogen transport for procedure A were approximately equal to the values obtained by disregarding the nitrogen transport, whereas those for procedure B were higher (up to 40%), than the values obtained disregarding the nitrogen transport.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1467-1484 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A steady-state method for kla determination has been presented using the Michaelis-Menten two-substrate kinetic equation for oxidation of glucose in the presence of the enzymes glucose oxidase and excess catalase. The conditions have been specified where spontaneous hydrolysis of lactone is sufficiently rapid, thus eliminating inhibitory action of lactone on the oxidation. In glucose oxidase-free batches, the kla values were determined using various modification of the dynamic method. The dynamic methods in which gas interchange was effected without interrupting aeration and agitation of the batch yielded erroneously lower kla values as compared to the results of steady-state methods if the measured kla value was higher than 0.03 s-1. The values yielded by the dynamic method in which the gas interchange was effected at the same time with turning on aeration and agitation of the batch agreed with values resulting from the steady-state method provided that the measured kla values were lower than 0.08-1 and the simultaneous interfacial transport of nitrogen and oxygen had been taken into account in the evaluation. At kla values higher than 0.08 -1, this modification of the dynamic method also yielded lower kla values as compared with the outcome of the steady-state method. The experiments performed do not, however, allow one to decide unambiguously on the whether these lower kla values are due to failure of the adopted model to describe adequately the dynamic behavior of the system or whether they are true values differing from those yielded by the steady-state method on account of different physical properties of compared batches.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 39-48 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Various experimental procedures for the determination of transient characteristics with significant liquid film effects were tested. A comparison between transient characteristics obtained experimentally and those calculated from rational models indicates that all procedures but one give highly inconsistent results. Recalculation of transient characteristics with no liquid film (easily measured in the gas phase) to that with liquid film (occurring in viscous liquids) is recommended as well as the selected experimental procedure which yields consistent results in the situations where the steady-state probe reading is decreased up to one-half due to the liquid film.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 482-490 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Empirical equations used so for for computing kla in mechanically agitated aerated vessels agree well with the measured dependence of Kla on the power input of the stirrer and the superficial velocity of the gas. However, they do not fit the dependence of Kla on the physical properties of the liquid batch. From the data published so far it can be deduced that the equations suitable for the description of the dependence of kmola on the liquid physical properties must include some independent variable, which characterizes the rate of coalescence of the bubbles. About 400 experimental values of Kla were compared with those calculated from different relations. This comparison shows that the rate of coalescence for the aqueous electrolyte solutions is well described on the basis of the Gibbs theory of adsorption of the solute in the surface layer of the solution.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 903-912 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 22 (1980), S. 2515-2527 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of oxidation of glucose solution by dissolved oxygen in the presence of glucose oxidase and excess catalase were studied both theoretically and experimentally. The kinetic model used was based on the detailed mechanism of the reaction. The description of the model is given by the Michaelis-Menten equation for the case of two substrates. The experiments were carried out in a closed reactor at a temperature of 25°C and pH 5.55. Commercial enzymes were used. Kinetic constants of the reaction were evaluated by fitting the oxygen concentration profiles calculated from the model to those found experimentally, by the method of nonlinear regression. The rate of D-glucose mutarotation to α and β form, and distortion of data caused by the dynamics of the applied oxygen probe were taken into account. The determined kinetic constants of the reactions are in good agreement with those given in the literature for purified enzymes. Adoption of literature kinetic data of this reaction to the determination of aeration capacity of fermentors by means of glucose oxidase systems has proved possible.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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