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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 37 (1992), S. 44-45 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The comparative effects of Pluronic on cell growth of hybridomas were studied. The addition of 0.05% Pluronic decreased the steady-state cell number in continuous culture by about 12% compared to a non-supplemented culture. In short-term experiments, results demonstrated a gradual decrease in cell number with increasing concentration of Pluronic. Such growth inhibition was found to be a result of lowering the rate of DNA synthesis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 1028-1033 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The abilities of various methods of oxygenation to meet the demands of high-cell-density culture were investigated using a spin filter perfusion system in a bench-top bioreactor. Oxygen demand at high cell density could not be met by sparging with air inside a spin filter (oxygen transfer values in this condition were comparable with those for surface aeration). Sparging with air outside a spin filter gave adequate oxygen transfer for the support of cell concentrations above 107 ml−1 in fully aerobic conditions but the addition of antifoam to control foaming caused blockage of the spinfilter mesh. Bubble-free aeration through immersed silicone tubing with pure oxygen gave similar oxygen transfer rates to that of sparging with air but without the problems of bubble damage and fouling of the spin filter. A supra-optimal level of dissolved oxygen (478% air saturation) inhibited cell growth. However, cells could recover from this stress and reach high density after reduction of the dissolved oxygen level to 50% air saturation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 1471-1477 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 1903-1929 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dispersion and mass-transfer characteristics and fluidization parameters influencing the performance of a small pilot-plant immobilized enzyme reactor are evaluated. The suitability of a dispersed plug-flow model to predict the conversions obtained in the enzymatic reaction (starch → glucose) catalyzed by amyloglucosidase immobilized to solid and porous carriers is assessed. The performance of a fluidized-bed reactor is compared on the basis of a normalized residence time with that of a fixed bed and found to be superior.
    Additional Material: 15 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 88-92 
    ISSN: 0006-3592
    Keywords: cell cycle ; hydrodynamic forces ; apoptosis ; cell culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Exposure of animal cells to intense hydrodynamic forces exerted in turbulent capillary flow, and by controiled agitation and aeration, resulted in preferential destruction of S and G2 cells and the extent of destruction of these cells was dependent upon the intensity of the action. The loss of these cells was possibly due to their larger size. However, the appearance of large numbers of membrane-bound vesicular structures similar to apoptotic bodies as well as cells with low DNA stainability (in a sub-G1 peak) suggested that the action of adverse hydrodynamic forces on these large cells may at least in part be to induce an apoptotic response. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 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 44 (1994), S. 720-726 
    ISSN: 0006-3592
    Keywords: cell death ; apoptosis ; hybridoma cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The incidence of apoptotic and necrotic cell death was compared in CHO, SF9 insect cells and murine plasmacytoma (J558L) and hybridoma (TB/C3) cells during in vitro cultivation in batch cultures. Acridine orange staining and fluorescence microscopy enabled the visualization of a classic morphological feature of apoptotic cell, the presence of condensed and/or fragmented chromatin. DNA gel electrophoresis was employed to show an additional characteristic of the process, the endonuclease-mediated fragmentation of DNA into multiples of 180 base pairs. The levels of apoptosis at the end of batch cultures of plasmacytoma and hybridoma cell lines were found to be 60% and 90% of total dead cells, respectively. However, employing the above-mentioned techniques, the biochemical and morphological features of apoptosis were not found in CHO and SF9 insect cells. Some factors affecting the induction of apoptosis during the batch culture of the hybridoma and plasmacytoma cell lines were identified. The most effective inducer was found to be glutamine limitation, followed by (in order of importance) serum limitation, glucose limitation, and ammonia toxicity. Blockage of the cell cycle of the plasmacytoma and hybridoma cells using thymidine resulted in the induction of apoptosis. This has important implications for the development of cell culture processes that minimize cell division and thereby increase specific productivity. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 463-472 
    ISSN: 0006-3592
    Keywords: apoptosis ; animal cell death ; hybridoma cells ; agitation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The question is addressed as to whether cells which are subject to high-energy dissipation rates in agitated bioreactors show an apoptotic response. Murine hybridoma cells in batch culture were agitated in bench-scale (1-L) bioreactors without gas sparging. At an energy dissipation rate of 1.5 W m-3 there was no apparent damage. At 320 W m-3 cell viability declined, and increasing proportions of the dead cells displayed the morphological features of apoptosis, but necrosis also remained as a significant mechanism of death. When cells were subjected to the intensive energy dissipation rate of 1870 W m-3 in a bioreactor without gas headspace, the cell number dropped by 50% within 2 h and a subpopulation of smaller-sized cells emerged. This excluded trypan blue but showed some apoptotic characteristics such as reduced and condensed DNA content and low F-actin content. The incidence of apoptotic activity was further demonstrated by the appearance of numerous apoptotic bodies. Analysis of the cell cycles of both small and normal size populations indicated that greater proportions of S and G2 cells had become apoptotic and there was evidence of preferential survival of G1 cells. It is suggested that two mechanisms of cell death are apparent in hydrodynamically stressful situations, but their relative expression depends on the energy dissipation rate. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cytotechnology 4 (1990), S. 13-28 
    ISSN: 1573-0778
    Keywords: monoclonal antibody ; hybridoma ; electron microscopy ; endoplasmic reticulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Electron microscopy of mouse hybridoma cell lines shows that the major difference between non, low and high producer cell lines is the amount of endoplasmic reticulum. Vesicular-tubular or cavernous structures of endoplasmic reticulum, which can survive long after cell death, are particularly abundant in producer cell lines. Immunogold labelling with anti-mouse IgG reveals that antibodies are predominantly located in these structures. The cell membrane undergoes structural changes during the late stages of batch culture with the disappearance of microvilli and the appearance of blebs and deep indentations. Necrosis disrupts the cytoplasmic structures and the nucleus is last to degrade.
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  • 9
    ISSN: 1573-0778
    Keywords: hybridoma cell culture ; cell cycle ; flow cytometry ; cell size ; mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Cell cycle, cell size and rhodamine 123 fluorescence in cell populations of two batch cultures were analysed and quantified with a fluorescence-activated cell sorter (FACS). Two cultures derived from either exponential or stationary phase innocula were investigated in order to demonstrate the dependency of the subsequent cell growth on innoculum condition. The results demonstrated that the level of activity of cells in the innoculum culture could have a significant effect on cellular activity during the initial phase of the inoculated culture, as it advances through its growth cycle. Positive correlation was found between the cell size and mitochondrial activity (as measured by rhodamine 123 uptake) with S and G2 fractions as the cell progressed through the cell cycle. The enumeration of the fractions of cell cycle phases has helped in prediction of the changes in cell numbers following perturbation of the culture condition.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cytotechnology 24 (1997), S. 161-168 
    ISSN: 1573-0778
    Keywords: cell number ; flow cytometry ; proliferationassay ; viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A simple, rapid and reliable method has been developed for assessing the number and viability of cells, as well as cell size, in suspension culture by the use of flow cytometry. Propidium iodide exclusion is used for viability determination and fluorescent beads serve as an internal standard for cell enumeration. The main advantages of this method are its ability to handle a large number of samples with a high degree of precision and its specificity in detecting viable cells quantitatively in a heterogeneous culture of living and dead cells and debris. The method shows only a fraction of the variation found in the haemacytometer/trypan blue counting method due to its very low operator dependence. CHO - Chinese hamster ovary; FCS - Foetal calf serum; FS - Forward scatter light; MTT - 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide; NCS - newborn calf serum; PBS - Phosphate buffered saline; PI - Propidium iodide; SS - Side scatter light.
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