PubMed Health⌕ Search

Biomedical subjects

R E Spier

Publications and source records attributed to R E Spier.

At least 19 recordsLinked to original sources
PubMed1992

Humans and viruses determine the nature of virus vaccine production processes.

Vaccine production processes result from the interaction between humans with a particular cell and virus system. The factors that control progress lie not only in the nature of the virus and animal cell but also in the history of the environment in which the process is to be developed. This latter constraint strongly influences the nature of the technical process that is chosen for the production of the vaccine rather than the achievement of efficiency based on one or other of the many possible engineering parameters of the virus production process. In addition to this it is also clear that we have much to learn about the production of viruses from animal cells in culture and that we may be aided by changing our present paradigm of the "virus as a cellular enemy" to that of the "viruses are the cell's best friend".

Animals↗
PubMed1992

Relationship between hybridoma growth and monoclonal antibody production.

Factors affecting cell growth and antibody production in a mouse hybridoma were investigated. Antibody was produced during the growth and decline phases of a batch culture with an increase in the specific rate of antibody production during the decline phase. The specific rate of antibody production was also increased in cells arrested by 2 mM thymidine, suggesting that cell proliferation and antibody production can be uncoupled. Reduced serum concentrations resulted in lower cell growth rates but increased antibody production rates. However, this trend was reversed in hybridomas which had been arrested by thymidine, since the highest antibody production rate was associated with high serum concentrations. Likewise, in proliferating cells, the optimum pH for antibody production (pH 6.8) was lower than the optimum pH for cell growth (pH 7.2), whereas in thymidine-blocked cells, the highest antibody production rate was at pH 7.2. High antibody production rates and product yields were also associated with low growth rates in continuous cultures. The possibility that antibody was under cell cycle control was investigated in synchronized hybridoma cultures. Antibody production occurred during G1 and G2 with a decline in the M phase and evidence of a further decline in the S phase. Thus antibody production was not restricted to the G1 and S phase in this hybridoma.

Animals↗
PubMed1992

Foaming and media surfactant effects on the cultivation of animal cells in stirred and sparged bioreactors.

Foam formation and the subsequent cell damage/losses in the foam layer were found to be the major problems affecting cell growth and monoclonal antibody (MAb) production in stirred and sparged bioreactors for both serum-supplemented and serum-free media. Surfactants in the culture media had a profound effect on cell growth by changing both the properties of bubbles and the qualities of foam formed. Comparable cell growth and MAb production in sparged bioreactors and in stirred and surface-aerated control cultures were observed only in Pluronic F-68 containing culture media. In media devoid of Pluronic F-68, cells became more sensitive to direct bubble aeration in the presence of antifoam agent which was used to suppress foam formation. Compared with serum-supplemented medium, more severe cell damage effects were observed in serum-free medium. In addition, serum-free medium devoid of cells was partially degraded under continuous air sparging. The mechanism of this damage effect was not clear. Pluronic F-68 provided protective effect to cells but not to the medium. A theoretical model based on the surface active properties of Pluronic F-68 was proposed to account for its protective effect on cell growth. Optimum media surfactant composition in terms of maximum cell growth and minimum foam formation was proposed for stirred and sparged animal cell bioreactor.

Animals↗
PubMed1991

There are viruses and viruses.....

Life has its problems. To succeed it has to survive: to survive it has to sacrifice its identity. And viruses have their fingers in the essence of it all. Consider the situation. There are useful genes. Such genes promote the survival of the individuals which house them. It is not unreasonable, therefore, to expect that an enterprising life-form would seek to gain advantage from the existence of such useful genes by distributing them around the life forms which are not so blessed. This achieves two effects. It justifies the existence of a class of organisms which serve as gene transporters (vectors) and it provides the recipient with benefit (a situation from which the transporter can also gain). Of course, the system can have its teething troubles as in the case of the transporter that provides a package which does damage and thereby decreases the survival of both the recipient and its invader. Yet, over a billion or so years, organisms of increasing complexity have emerged owing not a little to the processes of whole gene transfer by vector systems.

Biological Evolution↗
PubMed1991

Large-scale mammalian cell culture: methods, applications and products.

Animal cell cultures are used to generate products of enormous biotechnological value. These systems rely on conventional manufacturing techniques using organisms that are the result of either cell fusions or genetic engineering. A wealth of new techniques has allowed improvements and developments to be made in culture medium composition, cell modification, and bioreactor design and operation. This progress is expected to be commercially exploited as new products reach the market place.

Animals↗
PubMed1990

Methods for the estimation of the number and quality of animal cells immobilized in carbohydrate gels.

Rapid and reliable methods for the determination of survival, proliferation, and metabolic activity of immobilized cells in gels are described. The first method is based on an MTT assay that measures qualitatively and quantitatively the metabolic activity of the cells. The second method determines cell number by measuring the amount of DNA available for Feulgen staining. In the third method, two fluorescent dyes are used to differentially stain viable and dead cells. The fourth method involves the use of glutaraldehyde to protect the cells when melting the gel to facilitate hemocytometric count. The presented techniques should help to test the efficiency of the immobilization procedures and to monitor the growth and survival of immobilized cells.

Animals↗