Biomedical subjects

R Roguet

Publications and source records attributed to R Roguet.

5 recordsLinked to original sources

PubMed1992

In vitro methods: their relevance and complementarity in ocular safety assessment.

Ocular irritation includes a wide variety of mechanisms some of which can be explored by in vitro methods. For example, the effects on epithelial cells that constitute the outer layers of both the conjunctiva and the cornea may result in direct cytotoxicity or impairment of cellular functions -such as impermeability-, phenomena that can be explored in vitro. Irritancy may also involve inflammation of the conjunctival connective tissue and of the corneal stroma with its vascular and cellular features; effects on the stroma can lead to the opacification of the cornea; this last phenomenon may be the consequence of mechanisms such as modification of the structure of proteins or changes in stroma hydration which in particular is closely related to corneal endothelium metabolic activity. Recovery after eye injury depends partly on the extent of ocular damage and on the residual mitotic activity of the remaining cells. We have studied 41 surfactants, lotions and shampoos in 6 to 8 in vitro methods each one exploring one or two endpoints that could be linked to the ocular irritancy phenomena described above. In vivo ocular irritancy data for these materials from previous studies were compared to in vitro results. The results obtained show that -among the techniques that were investigated and for the categories of substances that were studied- the Het-CAM test and more particularly the endpoint that is related to vascular effects gives the best assessment of acute ocular irritancy (Spearman's rho coefficients between in vivo and in vitro data greater than 0.90); however, cell culture methods, especially one based on short contact time between cells and products and on evaluation of early toxic effects, also proved interesting (Spearman's rho coefficients between in vivo and in vitro data greater than 0.85). Moreover, the isolated cornea opacity and permeability test gave complementary information more related to recovery from surfactant-induced damage. These encouraging results lead us to consider in vitro ocular safety assessment with optimism for the categories of products investigated.

Allantois↗

PubMed1978

Specific modifications of hepatoma cell-surface glycoproteins with enzymes. Effects on in vitro growth as investigated by the use of lectins.

The effects of enzymic treatment on the interactions between Zajdela's tumor cells and various lectins. Concanavalin A (ConA); Wheat Germ Agglutinin (WGA); Robinia lectin; have been studied. (1) The number of lectin-binding sites and the affinity constants were investigated. (2) The effects of the lectins on cell growth and [3H]thymidine incorporation were studied on untreated and enzyme-treated cells. It was observed that treatment of tumor cells with neuraminidase resulted in a change in the binding characteristics of each lectin. However, additional treatment of the cells with galactose oxidase had no further effect on lectin binding. ConA and Robinia lectin induced a decrease of the untreated tumor cell growth and a stimulation of the [3H]thymidine incorporation. This paradoxal result may be explained as a consequence of the stimulation of the [3H]thymidine uptake observed in the presence of lectins. The enzymatic treatments themselves did not change the cell growth although they did induce a change in the effect of ConA and Robinia lectin on cell growth and [3H]thymidine incorporation. As a result of neuraminidase treatment, the effects of ConA were totally suppressed but those of Robinia lectin only partially. Although WGA interacted with untreated and enzyme-treated cell surfaces, it had no effect on tumor cell growth nor [3H]thymidine incorporation. The results are discussed in terms of lectin transport.

Animals↗

PubMed1976

Embryo cell surfaces--lectin binding and cell proliferation.

The interaction between chick embryo fibroblasts and various lectins has been studied at different stages of embryo development. There is evidence that Robinia lectin, Dolichos lectin, and Concanavalin A decrease cell number and proportion of cells incorporating [3H] thymidine in case of 8- and 10-day-old chick embryo fibroblasts, whereas they stimulated the proliferation of 16-day-old embryo cells. No effect was noticed in 12-day cells. These results suggest that some cell surface changes occur during embryo development. The site number of Dolichos lectin remains the same during embryo development, and the affinity constant decreases. The site number of Robinia lectin and Concanavalin A decreases from the 8th to the 12th day of development, and slowly increases on the 16-day cells, the affinity constant remaining rather constant. The results indicate that the age-dependent effect of lectin on embryo cells could not be directly related to the number of lectin-binding sites. Competitive binding experiments revealed that Dolichos receptor sites were distincts from binding sites of Robinia lectin and Concanavalin A, and Robina receptor sites distinct from those of concanavalin A. Lectin effects on embryo fibroblasts were very specific as determined by inhibitory assays.

Animals↗

PubMed1975

Interaction between Dolichos biflorus lectin and chick embryonic fibroblasts at different stages of development.

The interaction between chick embryo fibroblasts and A1-specific blood group Dolichos biflorus lectin has been studied at various stages of embryo development. The site number ((0.26 plus or minus 0.03)-10-6 sites/cell) remains the same during development whereas the affinity constant apparently decreases from 8-day cells onwards. The effects of cell number, temperature and time course on the Dolichos binding to fibroblasts were not age dependent. Competitive binding experiments revealed that Dolichos receptor sites were distinct from binding sites fo Robina pseudoacacia lectin and concanavalin A, but partially related to binding sites of Ricinus lectin. Thymidine incorporation by fibroblasts in the presence of Dolichos lectin was age dependent. It was inhibited in 6-day cells and weakly stimulated in 16-day cells, but not modified in 12-day cells. Dolichos lectin effects on embryo fibroblasts were very specific because both binding to cells and effect on thymidine incorporation were blocked by N-acetylgalactosamine, the determinant of Dolichos lectin, as well as by Dolichos antiserum.

Animals↗

PubMed1975

Changes in lectin-induced deoxyribonucleic acid synthesis in cultures of chick-embryo fibroblasts at various stages of development.

Concanavalin A and Robinia pseudoacacia lectin decreased [(3)H]thymidine incorporation into acid-insoluble material of fibroblasts cultured from 6-10-day chick embryos. In contrast, these lectins stimulated [(3)H]thymidine incorporation in cells from 16-day embryos. These effects are due to neither [(3)H]thymidine permeability modification nor toxicity of the lectins. The specificity of lectin action was proved by blocking experiments with alpha-methyl mannopyranoside and with anti-(Robinia lectin) serum.

Animals↗