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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 279 (1987), S. 536-542 
    ISSN: 1432-069X
    Keywords: Histamine ; IgE ; Prostaglandin E2 ; Basophils ; Atopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of arachidonic acid (AA) metabolism upon histamine release (HR) from human basophils after stimulation with anti-IgE was studied in 23 atopic and 11 normal individuals. HR occurred significantly faster in atopics than in normals; the total amount of HR after a 40 min incubation period was not significantly different between the two groups. Indomethacin and acetylsalicylic acid (ASA) increased the quantity of HR significantly both in atopics and normals without influencing the time course. Addition of exogenous PGE2 decreased HR; here atopics were more affected than normals 5 and 10 min after challenge with anti-IgE. Production of PGE2 after stimulation with anti-IgE was very low in both groups (in the range of 30–50 pg/106 cells) and often below detection limit (10–20 pg/ml). Addition of glutathione (GSH), a coenzyme of PGE2-isomerase, increased PGE2 production 2 to 5-fold during stimulation with anti-IgE. These data support the idea that arachidonic acid metabolites play an important role in modulating the “releasability” of human basophils. It is suggested that the basophils of atopic individuals may release their histamine faster than normals — perhaps on the basis of a more slowly acting endogenous feedback mechanism by PGE2. Both phenomena support the idea of an altered “releasability” of basophils from atopics compared to normals.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1436-5073
    Keywords: extended range Zeeman AAS ; calibration by curve fitting ; regression analysis ; automatic evaluation ; microcomputer-software package
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Perkin-Elmer Zeeman/5000 Atomic Absorption Spectrometer is only able to perform a calibration with three single standards or a one-point standard addition. The accuracy and precision of these methods are inappropriate in ETA-AAS, a computer-based data management is essential. A software package for calibration and evaluation was developed using curve fitting by linear regression based on a leastsquares fit when absorbances were transformed by the Baule-Mitscherlich function. The total analytical range could be covered by this method whether peak area or peak height values were fitted. The maximum absorbance levels could be calculated, as well. Absorbance signals were collected and stored by the “HGA-graphics” software (modified by Perkin-Elmer Nederland B. V.). The “Pecowriter” software was used for identifying data and file manipulations. The results of the calibration and evaluation can be stored on disk and/or printed. Calibration curves can be plotted on hardcopy output. The “Limit of Detection” and the “Characteristic Mass” can be calculated. The use of the CALIBRATION program is demonstrated by the calibration curves for the determination of Pb, Cd, As, Se, Cr, Al, Cu and Ni using mostly STPF-conditions. The performance of the method evaluated by the root mean square percent deviation of the fit is equal to the traditional curve-fitting function as well as to rational or quadratic functions. The use of the EVALUATION program is demonstrated by the results of the direct determination of lead in mineral waters.
    Type of Medium: Electronic Resource
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