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  • Articles  (5)
  • monoclonal antibody  (4)
  • nitrogen
  • Springer  (5)
  • Oxford University Press
  • Process Engineering, Biotechnology, Nutrition Technology  (5)
  • 1
    ISSN: 1572-8757
    Keywords: kinetics ; isotope-exchange ; nitrogen ; adsorption ; methane ; zeolite ; equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.
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  • 2
    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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  • 3
    ISSN: 1573-0778
    Keywords: Hybridoma cell culture ; monoclonal antibody ; exponentially fed-batch ; culture kinetics ; metabolism ; chemostat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Exponentially fed-batch cultures (EFBC) of a murine hybridoma in T-flasks were explored as a simple alternative experimental tool to chemostats for the study of metabolism, growth and monoclonal antibody (MAb) production kinetics. EFBC were operated in the variable volume mode using an exponentially increasing and predetermined stepwise feeding profile of fresh complete medium. The dynamic and steady-state behaviors of the EFBC coincided with those reported for chemostats at dilution rates below the maximum growth rate. In particular, steady-state for growth rate and concentration of viable cells, glucose, and lactate was attained at different dilution rates between 0.005 and 0.05 h−1. For such a range, the glucose and lactate metabolic quotients and the steady-state glucose concentration increased, whereas total MAb, volumetric, and specific MAb production rates decreased 65-, 6-, and 3-fold, respectively, with increasing dilution rates. The lactate from glucose yield remained relatively constant for dilution rates up to 0.03 h−1, where it started to decrease. In contrast, viability remained above 80% at high dilution rates but rapidly decreased at dilution rates below 0.02 h−1. No true washout occurred during operation above the maximum growth, as concluded from the constant viable cell number. However, growth rate decreased to as low as 0.01 h−1, suggesting the requirement of a minimum cell density, and concomitant autocrine growth factors, for growth. Chemostat operation drawbacks were avoided by EFBC in T-flasks. Namely, simple and stable operation was obtained at dilution rates ranging from very low to above the maximum growth rate. Furthermore, simultaneous operation of multiple experiments in reduced size was possible, minimizing start-up time, media and equipment costs.
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  • 4
    ISSN: 1573-0778
    Keywords: fluidized-bed reactor ; monoclonal antibody ; on-line monitoring ; sample system ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The monoclonal-antibody production of an immobilized hybridoma cell line cultivated in a fluidized-bed reactor was monitored on-line for nearly 900 h. The monoclonal antibody concentration was determined by an immuno affinity-chromatography method (ABICAP). Antibodies directed against the product, e.g. IgG, were immobilized on a micro-porous gel and packed in small columns. After all IgG present in the sample was bound to the immobilized antibodies, unbound proteins were removed by rinsing the column. Elution of the bound antibodies followed and the antibodies were determined by fluorescence. The analytical procedure was automated with a robotic device to enable on-line measurements. The correlation between the on-line determined data and antibody concentrations measured by HPLC was linear. A sampling system was constructed, which was based on a pneumatically actuated in-line membrane valve integrated into the circulation loop of the reactor. Separation of the cells from the sample stream was achieved by a depth filter made of glass-fibre, situated outside the reactor. Rapid obstruction of the filter by cells or cell debris and contamination of the sample system was avoided by intermittent rinsing of the sample system with a chemical solution. The intermittent rinsing of the filter, which had a surface of 4.8 cm2, resulted in an operational capacity of up to 40 samples (1.0 l total sample volume). Both the sampling system and the analytical device functioned without failure during this long-term culture. The culture temperature was varied between 34 and 40 °C. Raising the temperature from 34 up to 37 °C resulted in a simultaneous increase of growth and specific antibody production rate. Specific metabolic rates of glucose, lactate, glutamine and ammonium stayed constant in this temperature range. A further enhancement of temperature up to 40 °C had a negative effect on the growth rate, whereas the specific monoclonal antibody production rate showed a small increase. The other specific metabolic rates also increased in the temperature range between 38 to 40 °C.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cytotechnology 13 (1993), S. 51-53 
    ISSN: 1573-0778
    Keywords: cell recycle ; filtration ; hybridoma ; monoclonal antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract At the end of a hybridoma batch culture, the cells are usually discarded after separation from the culture broth. If, however, they are aseptically recycled into the reactor, the production process can be resumed simply by the addition of fresh medium. This cycle can then be repeated several times consecutively. In a test case, with a mouse hybridoma, we found antibody yields for each cycle in the same range as for a standard batch. In a 15 1 stirred tank reactor we could, within 6 days, produce 2.8 g of monoclonal antibody (MAb). This type of reactor operation allowed a doubling in the reactor volumetric productivity (mg/l/day).
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