Search PubMed⌕ Search

Biomedical subjects

A N Emery

Publications and source records attributed to A N Emery.

22 records · Page 2Linked to original sources
PubMed1990

Mechanisms and kinetics of monoclonal antibody synthesis and secretion in synchronous and asynchronous hybridoma cell cultures.

The kinetics of monoclonal antibody synthesis and secretion have been studied in synchronous and asynchronous mouse hybridoma cell cultures. Pulse-labelling of IgG followed by immunoprecipitation and quantitation of synthesized and secreted IgG in synchronous cultures show maximum production during G1/S phases. Secretion takes place through exocytotic release of vesicle contents. Pulse-chase experiments show that 71% of the synthesized IgG is secreted within 8 h of the pulsing period and only a further 4% is secreted by 22 h. Higher specific antibody production (QA) is obtained if (a) cells are arrested and then maintained in G1/S phases, (b) viability is decreased during the death phase of batch culture, (c) the dilution rate is decreased in continuous culture or (d) cells are subjected to hydrodynamically induced stress. The increase in QA in all these cases is mainly due to the passive release of the accumulated intracellular antibody. DNA and protein synthetic activity peak during the early exponential phase and decline rapidly during mid and late exponential and death phases. Metabolic activity however peaks up to 20 h after the peak in DNA synthesis, and declines similarly during the death phase. The data are consistent with the idea that slow growth and higher death rates increase QA and that Ig secretion is probably subject to complex intracellular control.

Animals↗
PubMed1987

On the evaluation of gas-liquid interfacial effects on hybridoma viability in bubble column bioreactors.

Sparger aeration, with or without mechanical agitation is the simplest method of providing an oxygen supply. Although earlier workers have demonstrated the sensitivity of mammalian cells to air bubbles, recent successful applications of the airlift principle to hybridoma culture indicate that under some conditions, the cells can withstand these effects. Therefore, this work has as its objective the elucidation of the relationship between gas-liquid interfaces and the survival of mammalian cells. Simple, 0.5 litre bubble columns with sintered discs are used batch-wise to study the effects of sparging on hybridomas and other mammalian cells in suspension culture. The effects of bubble diameters, superficial gas velocities and the non-ionic surfactant, Pluriol PE 6800, are investigated in cultures grown in RPM1 1640 with 5% foetal calf serum and 6 ppm silicone antifoam. From these studies it has become apparent that cell viability and survival in the presence of bubbles depend on: Cell type--Some cell lines are shown to be particularly sensitive to the presence of bubbles, although no gross morphological differences are detected by electron microscopy. Bubble sizes--At a superficial gas velocity of 0.42 X 10(-4)m/s (5 cc/min gas flow rate), small bubbles are shown to be more detrimental to the cells than the larger ones. Bubble frequency/superficial gas velocities--Increasing superficial gas velocities (0.42 X 10(-4) to 8.5 X 10(-4) m/s) result in decreasing cell viability. Where the presence of bubbles is detrimental to cell growth, the addition of the non-ionic surfactant, Pluriol PE 6800, has a concentration dependent protective effect. Surface tension, viscosity and bubble diameter data for typical medium will be presented. A novel application of microscopy to which video film systems can be applied for direct visualisation of the cells in the bubble column has been developed. From these studies, it is indicative that both the geometry of the system and the cell type are important in mammalian cell culture scale-up strategy.

Animals↗
PubMed1985

Physical conditions during batch culture of hybridomas in laboratory scale stirred tank reactors.

Due to the nature of animal cell suspension culture, physical conditions during growth such as pH, pO2, pCO2, agitation and aeration are inter-related and can exhibit individual or combined effects on cells. Evaluation of their influence on hybridoma growth and monoclonal antibody production can only be achieved by the use of well-instrumented stirred tank reactors. To determine the effect of the various physical conditions, mouse hybridomas, excreting antibody specific for human IgG, have been cultured in a 2 litre mechanically agitated round bottomed glass vessel, equipped with facilities to monitor and control these parameters during cell growth. Batch culture has been carried out at 36 degrees C in medium supplemented with 5% foetal calf serum (FCS). Clones have also been grown successfully with 2% FCS additions and in serum free medium, after careful adaptation periods. At least two clones have been assessed for comparative purposes.

Animals↗