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  • 1
    ISSN: 1423-0127
    Keywords: Heterologous gene expression ; Avian cells ; Erythropoietin ; Quail fibrosarcoma cells ; Duck embryo cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have explored the possibility of using avian cells for the expression of human proteins. We found that various avian cells including quail fibrosarcoma cells (QF), duck embryo cells (DE) and primary chicken embryo fibroblasts (CE) could efficiently be transfected with DNA by calcium phosphate coprecipitation, and that promoters which are transcriptionally active in mammalian cells also functioned well in these avian cells. Among the promoters we tested, the major immediate early promoter of human cytomegalovirus drove the highest level of chloramphenicol acetyl transferase (CAT) expression, outperforming the SV40 early promoter and the RSV LTR. Using the bacterial CAT gene as a reporter, we found that levels of CAT activity were higher in QF and DE cells than in mammalian cells such as CHO, HeLa, Vero and 293T cells. We further cloned a sequence encoding human erythropoietin (EPO) and compared its expression in QF and mammalian cells. Consistent with the CAT data, in transient transfection assays, QF cells produced higher levels of EPO than the mammalian cell lines tested. QF cells which can be passaged permanently were stably transfected with an EPO expression vector. The subcloned QF line was able to produce up to 1,700 U/ml EPO from 3 × 106 cells in 72 h. Purified QF-produced EPO showed a broad but discrete protein band, ranging from 33 to 41 kD and was as biologically active as CHO-produced EPO. Although a number of factors still remain to be optimized, our results demonstrate the potential of avian cells such as QF as producers of heterologous proteins.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 298-305 
    ISSN: 0006-3592
    Keywords: albumin ; transferrin ; proline ; hepatocytes ; primary culture ; serum free ; long term ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A serum-free culture system for primary hepatocytes which maintains stabel high-level hepatocyte function for prolonged periods in culture has been developed. Isolated rat primary hepatocytes were cultured in serum-free media between two layer of gelled collagen in a sandwich configuration which reinstates the cellular polarity necessary for long-term function in vitro. Thsee serum-free hepatocyte cultures maintained near physiological rates of albumin and transferrin secretion for a minimum of 26 days in culture. L-Proline was shown to be critical for both the approach to steady state and maximal level of protein secretion. Analysis of does-response data gave Km values of 2.9 and 1.7 μg/mL for albumin and transferrin secretion, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 579-588 
    ISSN: 0006-3592
    Keywords: hepatocytes ; microcarriers ; oxygen ; artificial liver ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Many potential applications of primary hepatocytes cultured on microcarriers, such as an artificial liver or hepatocyte transplantation, would benefit from having a large number of hepatocytes attached to each microcarrier. In addition, the supply of primary hepatocytes is usually limited, so the efficient utilization of hepatocytes during attachment to microcarriers is necessary. Several physical parameters involved in the attachment process have been investigated, and the number of cells attached per microcarrier and the fraction of hepatocytes which attach have been quantitatively monitored. Variation of the partial pressure of gas phase oxygen in the incubation flask produced significant effects on the attachment of hepatocytes to microcarriers, with higher partial pressures of oxygen found to be necessary for attachment. In addition, variation of fluid depth and cell number, both of which influence the partial pressure of oxygen at the cell surface, affected hepatocyte attachment. The partial pressure of oxygen at the cell surface as a function of the physical parameters was analyzed using a simple one-dimensional theoretical model. Variations in the cell-to-microcarrier ratio used for incubation indicate that a compromise must be made in terms of maximizing the number of cells per microcarrier and the fraction of total hepatocytes which attach. The maximum number of hepatocytes per microcarrier obtained in this work was approximately 100. The best attachment fraction, defined as the ratio of the number of hepatocytes attached to the total number added to the incubation, was approximately 90%. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 4
    Publication Date: 2016-07-02
    Description: ACS Sustainable Chemistry & Engineering DOI: 10.1021/acssuschemeng.6b00895
    Electronic ISSN: 2168-0485
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 5
    Publication Date: 2005-08-01
    Print ISSN: 0142-9612
    Electronic ISSN: 1878-5905
    Topics: Biology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Medicine
    Published by Elsevier
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