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Biomedical subjects

F Lacour

Publications and source records attributed to F Lacour.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

Adsorption of bovine serum albumin onto glassy carbon in a Couette flow. Effect of shear rate on the adsorption kinetics and on the structure of the adsorbed proteic layer.

Adsorption of bovine serum albumin onto glassy carbon is investigated by analysing the time-variation of the double-layer capacitance recorded during the adsorption process. The effect of shear rate is investigated under laminar conditions in a Couette flow. Stationary and sinusoidally modulated values of the shear rate are imposed over the (0-200 s-1) range. The flow conditions are shown to play an essential role by markedly modifying the rate of all the steps (three at most) involved in the adsorption mechanism. Moreover, the structure of the adsorbed layers in the intermediate and final states are also strongly modified, an increase of the shear rate increasing the interaction between the protein and the electrode. Piezoelectric properties of albumin are invoked to account for the experimental results.

Adsorption↗
PubMedDate not supplied

Changes in lymphocyte subpopulations in mice receiving a single injection of poly-A:U.

The electrophoretic mobility (EPM) of lymphoid cells from the spleen and thymus of A/Sn mice was studied after a single injection of a double-stranded synthetic polynucleotide, poly-A:U. The proportion of spleen T lymphocytes with a high EPM increased markedly and rose to 80% of the total cell population on the 3rd day. The percentage of high mobility lymphocytes began to decrease on the 4th day, but normal values were not reached until the 15th day. Important variations in electrophoretic distribution profiles of the thymic cells were also observed after poly-A:U inoculation. In the untreated athymic Nude mice, 5% of the spleen cells have a high mobility and are presumed to be T-cell precursors. After a single inoculation of poly-A:U, the percentage of these cells increased to 18%. This increase correlated well with the increase in theta-positive spleen cells.

Adjuvants, Immunologic↗
PubMedDate not supplied

Effects of Poly A. Poly U in vivo alterations of proportions of T and B cell subsets.

Spleens and thymuses of mice were examined for changes in lymphocyte subpopulations after in vivo treatment with a double stranded synthetic polynucleotide: Poly A.Poly U. The cell populations were characterized on a biophysical basis: the electrical charge of cell surface assessed by the anodic electrophoretic mobility. The proportion of spleen cells exhibiting a high electrophoretic mobility (T lymphocytes) increased markedly on the 3rd day after a single intravenous injection of Poly A.Poly U. In thymuses, early important variations in electrophoretic distribution profiles were observed after Poly A.Poly U injection, suggesting that adjuvant acts on T cells.

Animals↗
PubMedDate not supplied

Immunological recognition of three polynucleotide structures associating adenylic and uridylic acids.

The reactions of antibodies directed against the two double-stranded synthetic polyribonucleotide complexes poly(A).poly(U) or poly(I). poly(C) with three polynucleotide structures associating equimolar amounts of adenylic and uridylic acids were studied by immunodiffusion, quantitative precipitation and readioimmunoassay. The three sequence isomers of the same base composition but different nucleotide distribution were: the double helical complex poly(A).poly(U) containing two homopolymeric strands; the copolynucleotide poly(A-U) composed of a strictly repeating riboadenylic acid and ribouridylic acid sequence in both strands; and the copolymer poly(A,U) where the two strands contain both residues but in a random distribution. The three antigens reacted with anti-poly(A).poly(U) and antipoly(I).poly(C) antisera but not to the same extent. The random copolymer poly(A,U) reacted poorly with sera of both specificity. In contrast the reactivity of the alternating copolnucleotide poly(A-U) was widely different according to the specificity of the sera used. Whereas it was recognized by the anti-poly(A).poly(U) antibodies almost to the same extent than the homologous complex, its activity was much lower with anti-poly(I).poly(C) antisera. In addition, the relative efficiency of poly(A-U) was approximately 50 times lower than that of poly(A).poly(U) when tested with anti-poly(I).poly(C) antibody, thereby indicating recognition of different antigenic determinants in both duplexes. Antibodies directed against defined conformational determinants are therefore able to distinguish between three polynucleotide structures of the same base composition but different sequence.

Animals↗