• Journal of Life Science
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• v.9 no.3
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• pp.293-299
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• 1999

Accumulation of toxic waste byproducts in hybridoma culture can limit cell growth and monoclonal antibody (MAb) productivity, and one of the major toxic metabolites is lactate produced via glycolytic pathway of glucose metabolism. The factors affecting the glucose to lactate conversion rate were investigated. The conditions of high initial glucose concentration and high growth rate stimulated glucose to lactate conversion rate. The glucose-controlled fed-batch culture was investigated, and 19% reduction in lactate formation and 41% enhancement of MAb titer could be achieved by fed-batch culture.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.2
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• pp.110-117
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• 2000

Relationship between monoclonal antibody (MAb) productivity and growth rate, and effects of high cell density on MAb production rate increased with increasing specifis growth rate in both suspended and immobilized continuous cultures indicate a positively growth-associated relationship between MAb productivity and growth rate. moreover, the specific production rate was higher in the immobilized cell culture than that in suspended one at all dilution rates. In order to clarify these phenomana, MAb mPNA experession and cell cycle distribution were investigated in bacth cultures with immobilized cells and suspended cells. RT-PCR was used for observation of MAb mRNA expression and a two-color bromodeoxyuridine (BrdU)/propidium iodide (PI) flow cytometry method for determination of cell cycle distribution. The results revealed that MAb nRNA expression until dead phase, which was longer than in suspended cell. The cell cycle distribution patterns were observed almost the same for both immobilized and suspended cells. Such results may imply that a high cell density state has positive influence on the mRNA expression and on growth-associated Mab productivity of T0405 cells.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.419-424
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• 1998

An enzyme-linked immunosorbent assay (ELISA) was established for the detection of zearalenone by using monoclonal antibodies produced by Z-M-26 hybridoma cells when injected into a mouse and zearalenone-oxime-OV A conjugate. Zearalenone-oxime-OV A conjugates were diluted with carbonyl buffer, coated to 96 well microtiter plates at $4^{\circ}C$ overnight and blocked with 1% BSA overnight. One thousand times diluted antibody solution together with standard zearalenone or sample was added to 96-well microtiter plates and stood overnight. A secondary antibody conjugated with HRP was added and an hour later, enzyme substrate (TMBZ) solution was added for color develpment. Mter 30 minutes, coloring reaction was terminated by adding 2 N $H_2S0_4$ and the O.D. was measured at 450 nm. Detection range of this method was about 0.1~100 ppb. The established indirect competitive ELISA method was suitable for a rapid and effective analysis of zearalenone in agricultural products.

• The Journal of the Korean Society for Microbiology
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• v.21 no.1
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• pp.151-161
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• 1986

In order to develop sensitive and sepcific assay methods for E. coli heat labile enterotoxin(LT) hybridoma cell lines secreting LT specific monoclonal antibody were obtained. LT was purified from cell lysate of E. coli O15H11. The steps included disruption of bacteria by French pressure, DEAE Sephacel ion exchange chromatography, Sephadex G200 gel filtration, and second DEAE Sephacel ion exchange chromatography, successively. Spleen cells from Balb/c mice immunized with the purified LT and $HGPRT^{(-)}$ plasmacytomas, $P3{\times}63Ag8.V653$ were mixed and fused by 50% (w/v) PEG. Hybrid cells were grown in 308 wells out of 360 wells, and 13 wells out of them secreted antibodies reacting to LT. Among these hybridoma cell 1G8-1D1 cell line was selected since it had produced high-titered monoclonal antibody continuously. By using culture supernatant and ascites from 1G8-1D1 cells the monoclonal antibody was characterized, and an assay system for detecting enterotoxigenic E. coli was established by double sandwich enzyme-linked immunosorbent assay (ELISA). The following results were obtained. 1. Antibody titers of culture supernatant and ascites from 1G8-1D1 hybridoma cells were 512, and 102, 400, respectively by GM1-ELISA and its immunoglobulin class was IgM. 2. The maximum absorption ratio of 1G8-1D1 cell culture supernatant to LT was 90% at $300\;{\mu}g/ml$ of LT concentration. LT concentration shown at 50% absorption ratio was $103.45{\mu}g$ and the absorption ratio was decreased with tile reduction of LT concentration. This result suggests that monoclonal antibody from 1G8-1D1 hybridoma cell bound with LT specifically. 3. The reactivities of 1G8-1D1 cell culture supernatant to LT and V. cholerae enterotoxin(CT) were 0.886 and 0.142(O.D. at 492nm) measured by the GM1-ELISA, indicating 1G8-1D1 monoclonal antibody reacted specifically with LT but not with CT. 4. The addition of 0.1ml of ascites to 0.6mg and 0.12mg of LT decreased the vascular permeability factor to 41% and 44% respectively, but it did not completely neutralize LT. 5. By double sandwich ELISA using monoclonal antibody, as little as 75ng of the purified LT per ml could be detected. 6. The results by assay of detecting LT in culture supernatants of 14 wild strains E. coli isolated from diarrhea patients by the double sandwich ELISA were almost the same level as those by reverse passive latex agglutination.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.618-618
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• 2003

• Animal cells and systems
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• v.2 no.3
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• pp.403-410
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• 1998

The Tcf-1 (T cell specific factor-1) is a transcription factor uniquely expressed in T-lineage cells. Its expression is developmentally regulated, which is high in the specific stage of immature thymocytes, but is much lower in mature T cells. We cloned the Tcf-1 gene by subtractive hybridization and found it to be highly expressed in the thymus compared to the mRNA level in the spleen as expected. Since apoptosis occurs enormously in the thymus, we were interested in whether Tcf-1 gene expression could be regulated by such a high level of apoptotic assault. By using T cell hybridoma 70.7 cells, we induced apoptosis by incubating cells with anti-CD3 antibody in vitro. After apoptosis induction, Tcf-1 mRNA level was found to be significantly reduced compared to normal cells. Since Tcf-1 is a transcription factor for the CD3-e gene, we tested how CD3-e expression is regulated in apoptotic cells. The surface level of CD3-e protein is also down-regulated after apoptosis induction. Such a down-modulation of CD3-e protein would reduce the TCR/CD3 complex on the cell surface, which would be an important regulator for T cell apoptosis.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.3
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• pp.163-170
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• 2002

This report describes the use of a transtubular bioreactor to study the relative effects of diffusion versus perfusion of medium on antibody production by a hybridoma cell line. The study was performed with a high-density cell culture maintained in a serum-free, low-protein medium for 77 days. It was determined that the reactor possessed a macro-mixing pattern residence time distribution similar to a continuous stirred tank reactor (CSTR), However, due to the arrangement of the medium lines in the reactor, the flow patterns for nutrient distribution consist of largely independent medium path lengths ranging from short to long. When operated with cyclic, reversing, transtubular medium flow, some regions of the reactor (with short residence times) are more accessible to medium than others (with long residence times). From this standpoint, the reactor can be divided into three regions: a captive volume, which consists of medium primarily delivered via diffusion; a lapped volume, which provides nutrients through unilateral convection; and a swept volume, which operates through bilateral convection. The relative sizes of these three volumes were modified experimentally by changing the period over which the direction of medium flow was reversed from 15 min (larger captive volume) to 9 h (larger swept volume). The results suggest that antibody concentration increases as the size of the diffusion-limited (captive) volume is increased to a maximum at around 30 min with a sharp decrease thereafter. As reflected by changes in measured consumption of glucose and production of lactate, no significant difference in cellular metabolism occurred as the reactor was moved between these different states. These results indicate that the mode of operation of the transtubular bioreactor may influence antibody productivity under serum-free, low-protein conditions with minimal effects on cellular metabolism.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.2
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• pp.130-135
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• 2000

The characteristics of two different modes of perfusion culture, intermittent and continuous bleedings, were investigated by culturing the hybridoma cells producing von Willebrand Factor (vWF) monoclonal antibody (McAb) in a 15 L bioreactor without clogging the filter. Both culture methods exhibited similar profiles of cell density and metabolite concentrations during the culture period at the cell concentration of around 1${\times}$107 cells/mL. When the perfusion rate was increased, the intermittrnt bleeding culture showed problems of ammonia accumulation and decrease of cell viability. The continuous bleeding culture in terms of nutrient consumption and metabolite production kinetics. But the analysis of specific oxygen consumption rate showed that the specific oxygen consumption rate of intermittent bleeding culture was similar to that of exponential growth phase. The continuous bleeding culture showed higher specific oxygen consumption rate of intermittent bleeding culture. finally we proved the possibility of long-term operation of continuous bleeding culture and produced approximately 40 g of vWF McAb in a 15L bioreactor after one-month operation.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.481-488
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• 1989

A serum-free medium that could be used for the large-scale culture of mouse hybridoma to produce monoclonal antibodies was developed. The medium was based on a 1:1 mixture of Iscove's Modified Dulbecco's Medium and Ham's F-12, supplemented with insulin 10$\mu\textrm{g}$/$m\ell$, transferrin 10$\mu\textrm{g}$/$m\ell$, ethanolamine 10$\mu$M and selenium 30nM (designated EBM (enriched basal medium) with the supplements). The effect of various supplements of steroid hormones, vitamins, lipid and mineral salts was investigated and their optimal concentration was determined to replace fetal calf serum (PCS). These components were added respectively and then added by way of two or three combination to discern of which component combination was effective to the culture of hybridoma. As a result, serum-free medium KM3 (EBM with BSA 100$\mu\textrm{g}$/$m\ell$, mineral cocktail and 0.05% PEG) was deter-mined. The hybridoma Alps 25-3 cultured in this medium showed almost the same growth rate as in medium added with 2% fetal bovine serum. However, the antibody concentration from KM3 cultures was 80% of that obtained from culture with FCS. KM3 was also examined for the culture of other mouse hybridomas, KW, A4W & HCGK, and it was confirmed that it could support the growth of these hybridomas and the production of monoclonal antibodies.

• KSBB Journal
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• v.5 no.1
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• pp.87-94
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• 1990

Enhancement of hybridoma cell growth and monoclonal antibody(MAb) production by the addition of a small amount of serum into both serum-free medium and enriched medium was studied. The enriched medium was constructed by mixing a basal serum-free medium and a nutrient-fortified RPMI 1640 medium. It was supplemented with human serum albumin, insulin, transferrin, and monoethanolamine. It was found that addition of low concentration of serum with other serum-free supplements was favorable for growth of a mouse hybridoma 2c3.1 cells. The concentration of serum was determined to 0.5%. The maximum cell concentration obtained in this enriched medium supplemented with 0.5% fetal bovine serum (FBS) was $3.06{\times}10^6$ cells/ml and the concentration of secreted anti-Hepatitis surface antigen (antiHBsAg) MAb was $159.7{\mu\textrm{g}}\;/\;ml$ compared to $43{\mu\textrm{g}}\;/\;ml$ in RPMI 1640 medium with 10% FBS and $50{\mu\textrm{g}}\;/\;ml$ in previously-developed serum-free medium. The 2c3.1 cell growth and MAb production could be enhanced considerably by using the enriched medium supplemented with 0.5% FBS and serum-free supplements instead of RPMI 1640 medium or serum-free medium. The enhancement in MAb production in the enriched medium was more noticeable.