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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 308-318 
    ISSN: 0006-3592
    Keywords: hybridoma ; cell growth ; antibody production ; toxic waste removal ; electrical technique ; electrokinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ammonium and lactate are two known toxic products detrimental to mammalian cell growth and productivity. An electrokinetic technique, utilizing an electrophoretic mechanism, was developed to remove these cellular wastes in-situ from suspension hybridoma (ATCC CRL-1606) cultures to enhance cell growth and productivity. This technique applies continuously a dc electric field to selectively remove the electrically charged wastes. The experiments were shown to be successful in the removal of externally added 10 rnM ammonium and 45 mM lactate while maintaining the chemostatic condition of culture medium in a cell-free condition under an electric current density of 50 A/m2. Toxic levels of ammonium were added, ranging from 7.5 to 12.5 mM, at the start of the hybridoma culture, and the applied dc electric fields were able to completely remove these added materials. This in turn released the inhibition and restored the cell growth. Finally, this electrokinetic technique was applied to the batch and glutamine fed-batch hybridoma cultures. At an applied electric current density of 50 A/m2, this was able to completely remove cell-produced ammonium and increased the cell growth and antibody titer by 30% to 50%, respectively, compared to the control experiment in the absence of the electric field. Lastly, the applied electric current density of 50 A/m2 did not affect cellular functionalities such as glucose and glutamine consumption and antibody productivity.© 1995 John Wiley & Sons, Inc
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 149-157 
    ISSN: 0006-3592
    Keywords: mass transfer ; Escherichia coli ; cell cultures ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nutrient depletion and inhibitory end-product accumulation are the major problems for hydrogel-entrapment cell cultures. An electrokinetic technique was developed to enhance intrahydrogel mass transfer to overcome these problems. Escherichia coli cells (ATCC 15224) were entrapped in 3.2-mm-thick potassium-K-carrageenan and agarose hydrogel slabs. With a electric current density of 180A/m2 the cell densities were increased by 140%(from 3.9 to 9.6 dry cell weight [DCW] g/L) in potassium-K-carrageenan and by 80% (from 3.9 to 7.0 DCW g/L) in agarose. A mathematical model taking into account nutrient depletion, inhibitory end-product formation, and cell growth kinetics under facultatively anaerobic conditions was developed to rationalize the overall transport and biological behaviors in the hydrogel. The cell growth in hydrogel was successfully simulated. It is concluded that the augmented transports for glucose and inhibitory end-products accounted for these increases in cell growth. The increase in cell density in potassium-K-carrageenan was due to the enhanced removal of inhibitory end-products (through electroosmosis and electro-phoresis: 80%) and due to the augmented glucose transport (through electroosmosis: 20%). © 1995 John Wiley & Sons, Inc.
    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 47 (1995), S. 319-326 
    ISSN: 0006-3592
    Keywords: nutrient enrichment ; hybridorna ; electrical techniques ; electrokinetics ; ammonia ; lactate ; waste removal ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In-situ dc electric fields were applied to remove ammonium and lactate from suspension hybridoma cultures (ATCC-CRL-1606) which used enriched media. Nutrient concentration was increased fourfold above the normal concentration of DMEM to study enhanced protein product formation in a dc electric field. In the presence of the electric field, hybridoma growth and antibody production were increased 1.5-fold (from 3.7 × 106 to 9.1 × 106 viable cells/mL) and twofold (from 170 to 505 mg IgG/L), respectively, compared with the control. The effective removal of ammonium and lactate and increased concentrations of the various nutrients accounted for this enhancement. The enriched media caused the overflow metabolism of glucose, glutamine, and various essential amino acids. The overconsumption of glucose also produced substantial amounts of lactate, which in turn greatly increased the medium osmolarity. The increase in medium osmolarity is believed to be one of the causes of cell death in these culture systems.© 1995 John Wiley & Sons, Inc
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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