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Jutta Rehm - One of the best experts on this subject based on the ideXlab platform.
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high viable Cell Concentration fed batch cultures of hybridoma Cells through on line nutrient feeding
Biotechnology and Bioengineering, 1995Co-Authors: Weichang Zhou, Jutta RehmAbstract:A hybridoma Cell line was cultivated in fed-batch cultures using a low-protein, serum-free medium. On-line oxygen uptake rate (OUR) measurement was used to adjust the nutrient feeding rate based on glucose consumption, which was estimated on-line using the stoichiometric relations between glucose and oxygen consumption. Through on-line control of the nutrient feeding rate, not only sufficients were supplied for Cell growth and antibody production, but also the Concentrations of glucose and other important nutrients such as amino acids were maintained at low levels during the Cell growth phase. During the cultivation, Cell metabolism changed from high lactate production and low oxygen consumption to low lactate production and high oxygen consumption. As a result the accumulation of lactate was reduced and the growth phase was extended. In comparison with the batch cultures, in which Cells reached a Concentration of approximately 2 × 106 Cells/mL, a very high Concentration of 1.36 × 107 Cells/mL with a high Cell viability (>90%) was achieved in the fed-batch culture. By considering the consumption of glucose and amino acids, as well as the production of Cell mass, metabolites, and antibodies, a well-closed material balance was established. Our results demonstrate the value of coupling on-line OUR measurement and the stoichiometric realations for dynamic nutrient feeding in high Cell Concentration fed batch cultures. © 1995 John Wiley & Sons, Inc.
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high viable Cell Concentration fed batch cultures of hybridoma Cells through on line nutrient feeding
Biotechnology and Bioengineering, 1995Co-Authors: Weichang Zhou, Jutta RehmAbstract:A hybridoma Cell line was cultivated in fed-batch cultures using a low-protein, serum-free medium. On-line oxygen uptake rate (OUR) measurement was used to adjust the nutrient feeding rate based on glucose consumption, which was estimated on-line using the stoichiometric relations between glucose and oxygen consumption. Through on-line control of the nutrient feeding rate, not only sufficient were supplied for Cell growth and antibody production, but also the Concentrations of glucose and other important nutrients such as amino acids were maintained at low levels during the Cell growth phase. During the cultivation, Cell metabolism changed from high lactate production and low oxygen consumption to low lactate production and high oxygen consumption. As a result the accumulation of lactate was reduced and the growth phase was extended. In comparison with the batch cultures, in which Cells reached a Concentration of approximately 2 x 10(6) Cells/mL, a very high Concentration of 1.36 x 10(7) Cells/mL with a high Cell viability (>90%) was achieved in the fed-batch culture. By considering the consumption of glucose and amino acids, as well as the production of Cell mass, metabolites, and antibodies, a well-closed material balance was established. Our results demonstrate the value of coupling on-line OUR measurement and the stoichiometric relations for dynamic nutrient feeding in high Cell Concentration fed batch cultures.
Weichang Zhou - One of the best experts on this subject based on the ideXlab platform.
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high viable Cell Concentration fed batch cultures of hybridoma Cells through on line nutrient feeding
Biotechnology and Bioengineering, 1995Co-Authors: Weichang Zhou, Jutta RehmAbstract:A hybridoma Cell line was cultivated in fed-batch cultures using a low-protein, serum-free medium. On-line oxygen uptake rate (OUR) measurement was used to adjust the nutrient feeding rate based on glucose consumption, which was estimated on-line using the stoichiometric relations between glucose and oxygen consumption. Through on-line control of the nutrient feeding rate, not only sufficients were supplied for Cell growth and antibody production, but also the Concentrations of glucose and other important nutrients such as amino acids were maintained at low levels during the Cell growth phase. During the cultivation, Cell metabolism changed from high lactate production and low oxygen consumption to low lactate production and high oxygen consumption. As a result the accumulation of lactate was reduced and the growth phase was extended. In comparison with the batch cultures, in which Cells reached a Concentration of approximately 2 × 106 Cells/mL, a very high Concentration of 1.36 × 107 Cells/mL with a high Cell viability (>90%) was achieved in the fed-batch culture. By considering the consumption of glucose and amino acids, as well as the production of Cell mass, metabolites, and antibodies, a well-closed material balance was established. Our results demonstrate the value of coupling on-line OUR measurement and the stoichiometric realations for dynamic nutrient feeding in high Cell Concentration fed batch cultures. © 1995 John Wiley & Sons, Inc.
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high viable Cell Concentration fed batch cultures of hybridoma Cells through on line nutrient feeding
Biotechnology and Bioengineering, 1995Co-Authors: Weichang Zhou, Jutta RehmAbstract:A hybridoma Cell line was cultivated in fed-batch cultures using a low-protein, serum-free medium. On-line oxygen uptake rate (OUR) measurement was used to adjust the nutrient feeding rate based on glucose consumption, which was estimated on-line using the stoichiometric relations between glucose and oxygen consumption. Through on-line control of the nutrient feeding rate, not only sufficient were supplied for Cell growth and antibody production, but also the Concentrations of glucose and other important nutrients such as amino acids were maintained at low levels during the Cell growth phase. During the cultivation, Cell metabolism changed from high lactate production and low oxygen consumption to low lactate production and high oxygen consumption. As a result the accumulation of lactate was reduced and the growth phase was extended. In comparison with the batch cultures, in which Cells reached a Concentration of approximately 2 x 10(6) Cells/mL, a very high Concentration of 1.36 x 10(7) Cells/mL with a high Cell viability (>90%) was achieved in the fed-batch culture. By considering the consumption of glucose and amino acids, as well as the production of Cell mass, metabolites, and antibodies, a well-closed material balance was established. Our results demonstrate the value of coupling on-line OUR measurement and the stoichiometric relations for dynamic nutrient feeding in high Cell Concentration fed batch cultures.
Hasso Seibert - One of the best experts on this subject based on the ideXlab platform.
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cytotoxic potency of h2o2 in Cell cultures impact of Cell Concentration and exposure time
Free Radical Biology and Medicine, 2010Co-Authors: Michael Gulden, Anne Jess, Julia Kammann, Edmund Maser, Hasso SeibertAbstract:Abstract Using C6 glioma Cells in this study we investigated in detail how exposure time and Cell Concentration affect the cytotoxic potency of H2O2 in vitro. Median cytotoxic Concentrations (EC50) decreased from 500 to 30 μM with increasing incubation time from 1 to 24 h. Twenty-four hours proved to be sufficient to determine incipient cytotoxic Concentrations of H2O2. The incipient EC50 values were linearly related to the Cell Concentration. A Cell Concentration-independent median cytotoxic Cell dose (ED50) of 430 nmol/mg Cell protein or 860 nmol/107 Cells was derived. Median cytotoxic H2O2 Concentrations were completely eliminated from the culture medium at a rate proportional to both the H2O2 and the Cell Concentrations. In contrast to EC50 values the corresponding areas under the Concentration versus time curve (AUC) were independent of the Cell Concentration and amounted to 1800 μM × min. With decreasing Cell Concentration the H2O2 elimination decelerates and, thus, exposure to H2O2 applied as a bolus approaches a continuous exposure to a steady H2O2 Concentration. Taken together, our results indicate that the cytotoxic potency of H2O2 administered to cultured Cells as a bolus is characterized by the AUC, which depends on its initial Concentration, the ability of the Cells to eliminate H2O2, and the Cell Concentration. We recommend expressing the toxic potency of H2O2 in vitro by the incipient toxic Cell dose (e.g., nmol H2O2/mg Cell protein or nmol H2O2/107 Cells), in particular for comparative purposes.
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cytotoxic potency of h2o2 in Cell cultures impact of Cell Concentration and exposure time
Free Radical Biology and Medicine, 2010Co-Authors: Michael Gulden, Anne Jess, Julia Kammann, Edmund Maser, Hasso SeibertAbstract:Using C6 glioma Cells in this study we investigated in detail how exposure time and Cell Concentration affect the cytotoxic potency of H(2)O(2) in vitro. Median cytotoxic Concentrations (EC(50)) decreased from 500 to 30 μM with increasing incubation time from 1 to 24h. Twenty-four hours proved to be sufficient to determine incipient cytotoxic Concentrations of H(2)O(2). The incipient EC(50) values were linearly related to the Cell Concentration. A Cell Concentration-independent median cytotoxic Cell dose (ED(50)) of 430 nmol/mg Cell protein or 860 nmol/10(7) Cells was derived. Median cytotoxic H(2)O(2) Concentrations were completely eliminated from the culture medium at a rate proportional to both the H(2)O(2) and the Cell Concentrations. In contrast to EC(50) values the corresponding areas under the Concentration versus time curve (AUC) were independent of the Cell Concentration and amounted to 1800 μM×min. With decreasing Cell Concentration the H(2)O(2) elimination decelerates and, thus, exposure to H(2)O(2) applied as a bolus approaches a continuous exposure to a steady H(2)O(2) Concentration. Taken together, our results indicate that the cytotoxic potency of H(2)O(2) administered to cultured Cells as a bolus is characterized by the AUC, which depends on its initial Concentration, the ability of the Cells to eliminate H(2)O(2), and the Cell Concentration. We recommend expressing the toxic potency of H(2)O(2) in vitro by the incipient toxic Cell dose (e.g., nmol H(2)O(2)/mg Cell protein or nmol H(2)O(2)/10(7) Cells), in particular for comparative purposes.
Dohyung Kang - One of the best experts on this subject based on the ideXlab platform.
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lipid production in porphyridium cruentum grown under different culture conditions
Journal of Bioscience and Bioengineering, 2009Co-Authors: Jae Gun Han, Young Keun Kim, Seung Seop Kim, Myoung Hoon Jeong, Hyang Suk Jeong, Na Young Kim, Jeong Sub Cho, Won Byong Yoon, Shin Young Lee, Dohyung KangAbstract:Abstract Autotrophic growth of Porphyridium cruentum under 18:12 h and 12:12 h light:dark cycles showed the maximum Cell Concentration of 2.1 g-dry wt./L, whereas the specific growth rate, 0.042 (1/h), at 18:6 h is faster than that of 12:12 h, 0.031 (1/h), respectively. The highest lipid accumulation level, 19.3 (%, w/w), was achieved at 12:12 h cycle. Under dark cultivation condition with 10 g/L of glucose, the lipid accumulation in the Cell was 10.9 (%, w/w), whereas the heterotrophic growth with glycerol as the carbon resource showed low level of Cell Concentration and lipid production, compared to that of glucose. The glucose was decided to be a suitable carbon resource for the heterotrophic growth of P. cruentum . The lipids from P. cruentum seemed be feasible for biodiesel production, because over 30% of the lipid was C 16 –C 18:1 . The cultivation time and temperature were important factors to increase the maximum Cell Concentration. Extending the cultivation time helps maintain the maximum Cell Concentration, and higher lipid accumulation was achieved at 25 °C, compared to 35 °C. The fed-batch cultures showed that, under the light condition, the specific production rate was slightly decreased to 0.4% lipid/g-dry wt./day at the later stage, whereas, under the dark condition, the specific production rate was maintained to be a maximum value of 1.1% lipid/g-dry wt./day, even in the later stage of cultivation. The results indicate that the heterotrophic or 12:12 h cyclic mixotrophic growth of P. cruentum could be used for the production of biodiesel in long-term fed-batch cultivation of P. cruentum .
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lipid production in porphyridium cruentum grown under different culture conditions
Journal of Bioscience and Bioengineering, 2009Co-Authors: Jae Gun Han, Young Keun Kim, Seung Seop Kim, Myoung Hoon Jeong, Hyang Suk Jeong, Na Young Kim, Jeong Sub Cho, Won Byong Yoon, Shin Young Lee, Dohyung KangAbstract:Autotrophic growth of Porphyridium cruentum under 18:12 h and 12:12 h light:dark cycles showed the maximum Cell Concentration of 2.1 g-dry wt./L, whereas the specific growth rate, 0.042 (1/h), at 18:6 h is faster than that of 12:12 h, 0.031 (1/h), respectively. The highest lipid accumulation level, 19.3 (%, w/w), was achieved at 12:12 h cycle. Under dark cultivation condition with 10 g/L of glucose, the lipid accumulation in the Cell was 10.9 (%, w/w), whereas the heterotrophic growth with glycerol as the carbon resource showed low level of Cell Concentration and lipid production, compared to that of glucose. The glucose was decided to be a suitable carbon resource for the heterotrophic growth of P. cruentum. The lipids from P. cruentum seemed be feasible for biodiesel production, because over 30% of the lipid was C16-C(18:1). The cultivation time and temperature were important factors to increase the maximum Cell Concentration. Extending the cultivation time helps maintain the maximum Cell Concentration, and higher lipid accumulation was achieved at 25 degrees C, compared to 35 degrees C. The fed-batch cultures showed that, under the light condition, the specific production rate was slightly decreased to 0.4% lipid/g-dry wt./day at the later stage, whereas, under the dark condition, the specific production rate was maintained to be a maximum value of 1.1% lipid/g-dry wt./day, even in the later stage of cultivation. The results indicate that the heterotrophic or 12:12 h cyclic mixotrophic growth of P. cruentum could be used for the production of biodiesel in long-term fed-batch cultivation of P. cruentum.
Michael R Hamblin - One of the best experts on this subject based on the ideXlab platform.
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Effect of Cell-photosensitizer binding and Cell density on microbial photoinactivation, Antimicrob
2020Co-Authors: Tatiana N Demidova, Michael R HamblinAbstract:Photodynamic therapy involves the use of nontoxic dyes called photosensitizers and visible light to produce reactive oxygen species and Cell killing. It is being studied as an alternative method of killing pathogens in localized infections due to the increasing problem of multiantibiotic resistance. Although much has been learned about the mechanisms of microbial killing, there is still uncertainty about whether dyes must bind to and penetrate various classes of microbe in order to produce effective killing after illumination. In this report, we compare the interactions of three antimicrobial photosensitizers: rose bengal (RB), toluidine blue O (TBO), and a poly-L-lysine chlorin(e6) conjugate (pL-ce6) with representative members of three classes of pathogens; Escherichia coli (gram-negative bacteria), Staphylococcus aureus (gram-positive bacteria), Candida albicans (yeast). We compared fluence-dependent Cell survival after illumination with the appropriate wavelengths of light before and after extraCellular dye had been washed out and used three 10-fold dilutions of Cell Concentration. pL-ce6 was overall the most powerful photosensitizer, was equally effective with and without washing, and showed a strong dependence on Cell Concentration. TBO was less effective in all cases after washing, and the dependence on Cell Concentration was less pronounced. RB was ineffective after washing (except for S. aureus) but still showed a dependence on Cell Concentration. The overall order of susceptibility was S. aureus > E. coli > C. albicans, but C. albicans Cells were 10 to 50 times bigger than the bacteria. We conclude that the number and mass of the Cells compete both for available dye binding and for extraCellularly generated reactive oxygen species
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effect of Cell photosensitizer binding and Cell density on microbial photoinactivation
Antimicrobial Agents and Chemotherapy, 2005Co-Authors: Tatiana N Demidova, Michael R HamblinAbstract:Photodynamic therapy involves the use of nontoxic dyes called photosensitizers and visible light to produce reactive oxygen species and Cell killing. It is being studied as an alternative method of killing pathogens in localized infections due to the increasing problem of multiantibiotic resistance. Although much has been learned about the mechanisms of microbial killing, there is still uncertainty about whether dyes must bind to and penetrate various classes of microbe in order to produce effective killing after illumination. In this report, we compare the interactions of three antimicrobial photosensitizers: rose bengal (RB), toluidine blue O (TBO), and a poly-l-lysine chlorin(e6) conjugate (pL-ce6) with representative members of three classes of pathogens; Escherichia coli (gram-negative bacteria), Staphylococcus aureus (gram-positive bacteria), Candida albicans (yeast). We compared fluence-dependent Cell survival after illumination with the appropriate wavelengths of light before and after extraCellular dye had been washed out and used three 10-fold dilutions of Cell Concentration. pL-ce6 was overall the most powerful photosensitizer, was equally effective with and without washing, and showed a strong dependence on Cell Concentration. TBO was less effective in all cases after washing, and the dependence on Cell Concentration was less pronounced. RB was ineffective after washing (except for S. aureus) but still showed a dependence on Cell Concentration. The overall order of susceptibility was S. aureus > E. coli > C. albicans, but C. albicans Cells were 10 to 50 times bigger than the bacteria. We conclude that the number and mass of the Cells compete both for available dye binding and for extraCellularly generated reactive oxygen species.