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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 55 (1985), S. 305-318 
    ISSN: 1432-1246
    Keywords: Cr(III) compounds ; Cr(VI) compounds ; Conjugation of Cr(VI) compounds with erythrocytes ; Separation of erythrocytes ; Biological monitoring for Cr(VI)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Internal stress to chromium is only relevant in occupational medicine if it is due to the handling of hexavalent chromium. Cr(VI) ions, after uptake by inhalation or percutaneously are carried in the blood plasma and penetrate—depending on the concentration—into the erythrocytes. Due to the intracellular reduction to Cr(III) and the concurrent intracellular protein binding, the erythrocytes represent an easily accessible target organ for quantitative chromium determination after occupational exposure to Cr(VI) compounds. The results of an earlier experimental study indicate that human plasma too is capable of spontaneous reduction of Cr(VI) ions of up to 2 ppm to Cr(III). This plasma reduction capacity (PRC) can be increased and accelerated considerably by adding ascorbic acid (AA). These findings were supported in this investigation by proving a decreased binding of Cr(VI) inside the erythrocytes under the effect of AA. This leads to the assumption that only those Cr(VI) concentrations can penetrate the membrane of the erythrocytes and enter the cell which either come into contact with the membrane during the reduction process or exceed this limit concentration of 2 ppm. Only in these two instances can corresponding chromium findings be analyzed in isolated and washed erythrocytes. These results are compared with those obtained by conventional methods, such as Cr determination in the blood and/or urine. Our findings indicate that a single determination of chromium concentration in the erythrocytes will permit the monitoring of critical cases of Cr(VI) exposure. This is a new type of biological monitoring in the sense of a condensed longitudinal study, in order to find out whether threshold concentrations have been respected over a given period.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-2451
    Keywords: Total Artificial Heart Replacement ; Ventilation ; Blood Gases ; Blood Pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 18 Kälber (Körpergewicht = 100 ± 20 kg) mit einem künstlichen Totalherzen werden mit einem Bennett MA-1B Respirator beatmet. Unter den primären pulmonalen Komplikationen wird der Lungenatelektase eine vorrangige Bedeutung beigemessen. Die statische Thorax-Lungen-„Compliance” nimmt deutlich unter der Perfusion mit der Herz-Lungenmaschine und weniger deutlich unter der des künstlichen Totalherzens ab. Bei einem Atemzugvolumen von 11 ± 3 x 102 ml und einer Atemfrequenz von 10/min kommen Beatmungsdrucke von 20 bis 30 cm H2O zustande. Dabei werden möglichst niedrige Sauerstoffkonzentrationen in der Inspirationsluft angestrebt. Es wird mit feuchtwarmer Luft positiv-endexspiratorischen Drucken von 6-8 cm H2O und SICH beatmet. Diese Beatmungstechnik gewährleistet auch in kritischen Versuchsphasen eine normale arterielle Sauerstoffsättigung. Bei vier Versuchstieren war eine Spontanatmung unter Sauerstoffinsufflation über eine Nasensonde bis maximal 100 Std möglich. In Abhängigkeit von der in- und exspiratorischen Beatmungsphase werden Druckschwankungen im künstlichen Totalherzen sowie in der Arteria pulmonalis und in der Aorta infolge von Änderungen erstens der Lage des künstlichen Totalherzens und zweitens der Lungengefäßkapazität analysiert.
    Notes: Summary Eighteen calves (weight: 100 ± 30 kg) with a total artificial heart are ventilated by a Bennett MA-1B respirator. The atelectasis of the lung seems to be the most important complication in the respiratory system. The static thoraxlung-”compliance“ decreases relatively more during HLM-perfusion than during TAH-perfusion. The tidal volume of 11 ± 3 x 102 ml, combined with a frequency of 10/min leads to a breathing pressure of 20 to 30 cm H2O. Humidified, warm gases, PEEP- (6 to 8 cm H2) and SIGH-ventilation are applied. The oxygen concentration of the inspired gas is kept as low as possible. Generally this ventilation technique provides a normal arterial oxygen saturation. Four animals substituted by O2-insufflation breathed spontaneously, maximal 100 h. Several changes of blood pressure in the artificial heart, the pulmonary artery and the aorta depend on the phase of ventilation, which may be influenced by a change of artificial heart's position and of the lung-vessels' capacity.
    Type of Medium: Electronic Resource
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