Biomedical subjects
Publications and source records attributed to J Frappa.
Study of ecto-5'-nucleotidase was performed in cultured epithelial cells, infected with vesicular stomatitis virus (VSV). Changes in the enzymatic activity were measured in terms of TCID50 and exposure time. The effects of an enzyme inhibitor, Con A, were also investigated during the interaction between virus and cells.
A comparative study of the production of IFN beta by human skin fibroblasts in monolayers was carried out using induction by NDV and poly I - poly C. The induction by polynucleotides produced significantly higher IFN beta titers. An attempt to grow those diploid cells on microcarriers resulted in a failure.
Urokinase was obtained from cultured cells of human fetal kidneys. Ultrafiltration on an Amicon cell and purification by gel filtration chromatography (Ultrogel ACA54) yielded two molecules capable of activating plasminogen into plasmin. Their molecular weights were respectively 47,500 and 31,500 daltons. The first one showed more active than the latter. In this experiment, only small amounts of Urokinase were harvested. The yield could be enhanced using activators (pronase, glycine) or adapting fetal cells to large scale cultures.
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In prelminary studies, growth of diploid cells (fetal calf buccal cells and chick embryo fibroblasts on dextran microcarriers was studied and compared to growth in monolayer. Growth coefficients obtained were always greater (by 2 fold) when microcarriers were used. Moreover, this technique had the advantage of reducing the number of manipulations and hence the risk of contamination. In two series of experiments, buccal epithelial cells were infected with vescicular stomatitis virus. Good virus multiplication was obtained.
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5'-nucleotidase activity of cultured diploïd cells was measured using intact suspended cells. This depended on the substrate amount, but did not vary with Mg ++ concentration-Kinetic data were determined using Con. A,a specific inhibitor.
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