Batch production and growth kinetics of hybridomas

Batch cultures of mouse-mouse hybridoma cell lines were carried out and their growth and production kinetics investigated. Three main cell specific production patterns (expressed as pg IgG/cell x hour) were found, which can be used as a classification system for hybridoma cell lines (groups I–III). Cells showing the highest IgG-production at the beginning of the batch culture (during the lag and the onset of the log-phase) were classified as either group I and II. The difference was that cell lines of group II showed a second high cell specific production at the onset of the stationary and death phases. Cell lines of group III had a quite constant production of antibodies during their growth; but IgG secretion completely stopped after the beginning of the stationary phase. The implications of these three production patterns on the design of a production process are discussed.     

Evaluation of the serum-free medium MDSS2 for the production of poliovirus on vero cells in bioreactors

The serum-free medium MDSS2 (Merten et al., 1994), was used for cultivating Vero cells as well as for producing poliovirus (Sabin type 1) in static and in perfused micro-carrier cultures. At slightly different growth rates of 0.0120/h and 0.0106/h, respectively, static cultures in serum-containing (SCM) and serum-free (SFM) medium produced titers of ^106.75 and 10^6.67 TCID50 per 50 μl; signifying a specific productivity of 0.89 and 1.07 TCID50/c. Serum-free bioreactor cultures of Vero cells on DEAE-dextran microcarriers at 6.25 g/l produced cell densities of about 1.5×10⁶c/ml. After infection with virus (multiplicity of infection (MOI) 0.1–0.3) titers of about 6.3×10⁸ TCID50/ml were obtained, signifying an average specific productivity of 7.1 TCID50/c.h. Although these values were 4 and 2 fold, respectively, higher than in classical resum-based production processes (Montagnon et al. Dev. biol. Stand. 1981, 47, 55), a reference culture, for which cell growth was done in SCM and only virus production was done in SFM, produced 2×10⁹ TCID/ml with an average specific virus production rate of 18.9 TCID50/c.h. The differences between the fully serum-free and our reference process were mainly due to physiological differences of cells grown in SCM and SFM and also due to strongly modified consumption kinetics after virus infection leading to limitations of one or several essential medium compounds, like glucose and amino acids. Avoiding these limitations by increasing the residual concentration of glucose, glutamine, histidine, and SH-amino acids, led to specific virus production rates (of about 17.9 TCID59/c.h.) comparable to those found in the reference virus production process. The optimisation of the production of the poliovirus (Sabin 1) will be described with respect to the modification of the medium composition. This revised version was published online in June 2006 with corrections to the Cover Date.     

Serum-free medium for fermentor cultures of hybridomas

Hybridomas lend themselves particularly well to large scale cultivation techniques since they grow as single cells in suspension without requiring attachment to a substrate. Furthermore, many cell strains have been adapted to grow in serum-free (SF) media to a similar cell density and antibody production as in serum containing media. This review will concern itself mainly with the cultivation of hybridomas in SF-media in bioreactors of various types with the ultimate goal of producing large quantities of monoclonal antibodies (mAb).     

HIV Testing and Tolerance to Gender Based Violence: A Cross-Sectional Study in Zambia

This paper explores the effect of social relations and gender-based conflicts on the uptake of HIV testing in the South and Central provinces of Zambia. We conducted a community-based cross-sectional study of 1716 randomly selected individuals. Associations were examined using mixed-effect multivariable logistic regression. A total of 264 men (64%) and 268 women (56%) had never tested for HIV. The strongest determinants for not being tested were disruptive couple relationships (OR = 2.48 95% CI = 1.00–6.19); tolerance to gender-based violence (OR = 2.10 95% CI = 1.05–4.32) and fear of social rejection (OR = 1.48 95% CI = 1.23–1.80). In the Zambian context, unequal power relationships within the couple and the community seem to play a pivotal role in the decision to test which until now have been largely underestimated. Policies, programs and interventions to rapidly increase HIV testing need to urgently address gender-power inequity in relationships and prevent gender-based violence to reduce the negative impact on the lives of couples and families.     

Absolute Configuration and Predominant Conformations of a Chiral Crown Ether‐Based Colorimetric Sensor: A Vibrational Circular Dichroism Spectroscopy and DFT Study of Chiral Recognition

In the present work, we report a comprehensive vibrational circular dichroism (VCD) spectroscopic study of a chiral crown ether which features an axial chiral 3.3'‐diphenyl‐1,1'‐binaphthyl group as chiral moiety. By comparing the experimental and calculated VCD spectra, we show that the presumably very flexible crown ether preferably adopts only one ring conformation. Conformational flexibility is observed in the 2,4‐dinitrophenyl‐diazophenol group, which was previously introduced for colorimetric detection of primary amines and amino alcohols (Cho et al., Chirality 2011;23:349–353). The VCD spectra of the host–guest complexes with phenyl glycinol (PG) and phenyl alaninol have been studied as well. Based on the spectra calculated, it is shown that the diastereomeric complexes in general can be differentiated using VCD spectroscopy. Furthermore, the experimental VCD spectra of the complexes of the host molecule with PG support the above finding. Chirality 25:294–300, 2013. © 2013 Wiley Periodicals, Inc.     

State-of-the-art of the production of retroviral vectors

Retroviral vectors are still the vectors that are used in the majority of gene therapy trials for treatment of acquired or inherited diseases. In this review, the present state-of-the-art of the production of retroviral vectors and the most important parameters, such as the choice of the producer cell line, stability issues, medium additives, serum, type of bioreactor, that influence production issues is presented and discussed in light of an optimal vector production. The available literature data clearly indicate that, on one hand, the choice of the producer cell line is of utmost importance for obtaining a high level producer cell line, and that, on the other hand, the optimization of the medium, e.g. the replacement of glucose by fructose, has a potential for improving vector production rates and titers. Finally, the use of high-density perfusion culture systems for adherent as well as for suspension cells presents the best choice for a production system, because high cell densities imply high reactor specific production rates, which must be associated with a rapid harvest of the produced vector, thus avoiding vector inactivation due to an extended residence time. The overall optimization of the cultivation and production parameters will have a significant impact on the use of retroviral vectors for gene therapy purposes.