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Biomedical subjects

R E Spier

Publications and source records attributed to R E Spier.

At least 73 records · Page 4Linked to original sources
PubMed1988

Is a vaccine against AIDS possible?

The need to control the spread of human immunodeficiency viruses (HIVs) is unquestioned. Options for interference in the replicative cycle of HIV have been reviewed by Mitsuya and Broder. It is possible to propose antiviral agents which would be active at each stage of the cycle, but early experience suggests that highly selective antiviral agents which are free from side effects will not be easy to design and indeed random screening of existing medicinals may prove as rewarding. The natural history of HIV infection would suggest that vaccination is a strategy which requires urgent and exhaustive investigation.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Biochemistry of hybridoma technology.

The study of the metabolic requirements of cells in vitro requires both a qualitative definition of such nutrients and a quantitative analysis to optimize cell growth. The development of a rapid weaning procedure which allows cells to be cultured in low serum concentrations, facilitates the easy assessment of factors which regulate cell growth and antibody productivity. The novel combination of existing technology; the MTT (tetrazolium) cell ELISA (Mosman, 1983) and the TSP (Transferable solid phase) immuno ELISA provides a method for studying such factors.

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

The use of caged aeration for the growth of animal cells on microcarriers.

A simple, unaerated 0.1 litre microcarrier propagator was successfully sealed up to 1 litre using constant tip speed of the flexible wide blade stirrer. Further scale-up to 10 litres was not successful because of inadequate aeration. When this deficiency was corrected, using a sintered aerator, cell growth did not improve due to excessive foam production. This was overcome by carrying out the necessary aeration inside a special cage, located inside the propagator, which retained the bubbles and excluded the microcarriers. Using this device cell growth improved to levels similar to those obtained at the 0.1 and 1 litre scales.

Animals↗
PubMed1985

Factors affecting the productivity of glass sphere propagators.

The productivity of glass sphere propagators was studied at the 1 litre scale. For the growth of BKH monolayer cells there was an optimum pH of 7.0, but no critical upper level of dissolved oxygen. By controlling the levels of pH and dissolved oxygen the incubation period was reduced from 96 to 72 hours. In standard beds of glass spheres cell distribution and growth were uniform, but not in experimental tall, thin substrate beds. This was corrected by dividing the test systems into 3 parts and incubating them in series. Additional cell growth was achieved in the standard propagators by a replenishing exhausted medium. Cell productivity was also increased by supplying extra culture medium. By this means the number of cells recovered was similar to that from the 10 litre propagator. Such data is discussed to evaluate the largest practical scale of glass sphere propagators.

Animals↗
PubMed1983

The attachment of the foot-and-mouth disease virus Asia I Iran 1/73 to BHK suspension cells does not require virus specific cell receptors.

Experiments are described which show that a member of the picornaviridae (FMD virus Asia I Iran 1/73) attaches to BHK suspension cells in a manner which precludes a requirement for virus specific receptors on the cell plasma membrane. While it may be possible to demonstrate the apparent saturation of the cell surface with multiple doses of virus, an increase of the concentration of the dosing suspension results in more virus attachment. Indeed, it was found that with the amounts of virus which were made available it was not possible to saturate the ability of the cell to take up virus particles. This, coupled with the demonstration that the uptake of virus followed the pattern of uptake of gas molecules on to a solid surface (Freundlich adsorption isotherm), drew us to the conclusion that, in contrast to other reported systems with similar viruses and cells, the uptake of the FMD virus we used to BHK suspension cells did not require virus specific cell receptor sites.

Adsorption↗
PubMed1983

Isolation of capsid proteins of foot-and-mouth disease virus by chromatofocusing.

A method for the isolation of foot-and-mouth disease virus (FMDV) capsid proteins was developed. The FMDV capsid proteins VP1, VP2, VP3 and VP0 were isolated from sucrose gradient purified virus by chromatofocusing in a pH 7.4-4.0 gradient on Polybuffer exchanger PBE 94. Under the conditions used the proteins eluted in the sequence VP1, VP2, VP0 (when present) and VP3. Capsid protein VP4 did not elute and could not be isolated by this method. Protein concentration in the eluate was monitored by the use of a radiolabelled marker and recoveries of approximately 50% of the input marker could be achieved when using up to 15 mg of virus and a 30-ml column. The high capacity and relative simplicity of chromatofocusing make it a useful alternative to other methods of purifying proteins.

Animals↗
PubMed1983

An investigation into causes of resistance of a cloned line of BHK cells to a strain of foot-and-mouth disease virus.

The reduced ability of foot-and-mouth disease virus (FMDV) strain Asia 1 Iran 1/73 to replicate in the cloned BHK cell line AA7 was not due to lack of virus attachment at the cell surface. Instead, the main restriction in the viral growth cycle occurred during synthesis and processing of viral macromolecules, and/or during the earliest stages of their assembly. Reduced efficiency of penetration and uncoating of virus attached to the cells may also have contributed to inhibition of virus replication. Viral components or subviral particles did not accumulate and defective interfering particles were not detected. The reduced number of infective virions produced was released from infected cells at the normal rate. No interferon production could be demonstrated.

Animals↗
PubMed1983

The improvement and standardization of the simplified process for the production of foot and mouth disease virus from BHK suspension cells.

Improvements have been made to the methodology for the production of foot and mouth disease (FMD) virus from BHK 21 clone 13 suspension cells by the simplified process. Data derived from some 600 individual 8-1 cultures covering all seven types of FMD virus has been analysed. The production of virus was shown to (1) have no direct relationship to cell passage level and (2) to be inversely related to the cell multiplication factor observed during the cell growth cycle immediately prior to infection.

Aphthovirus↗
PubMed1983

An examination of the data and concepts germane to the oxygenation of cultured animal cells.

With the increasing demand for high productivity cultures (including unit process monolayer cultures) oxygenation has now become a problem much sooner in the scaling-up process. There are no problems with measuring the dissolved oxygen concentration, but maintaining a desired concentration is one of the major challenges in Animal Cell Technology. It is of key importance, because the oxygen level has critical effects on cell metabolism (13, 5, 9, 22, 40, 36) which not only affect cell growth but also the products that can be expressed by the cell. As the oxygen level for these two functions is often different (e.g. the production of Ig from lymphocytes (27) more attention must be paid to defining the optimal oxygen levels and methods whereby such levels can be maintained in the least destructive manner.

Animals↗