Ultrastructural changes in dog thyroid follicular cells elicit by concanavalin A in vitro

Summary Dog thyroid follicular cells exposed to concanavalin A (Con A) in vitro showed changes in cell shape, induction of colloid droplets and alterations in the distribution of microvilli. Cells exposed to Con A plus suboptimal concentrations of TSH (thyroid stimulating hormone) showed pseudopods and their cytoplasm was virtually occupied with colloid droplets. This findings suggest that Con A potentiated pseudopod and colloid droplet formation induced by TSH.Acknowledgments. The authors gratefully acknowledge the expert technical assistance of J. M. Greco. Supported by V. A. Research Funds.     

Morphological effects of concanavalin A on amphibian embryonic cells differentiating in vitro (author's transl)]

Concanavalin A exerts an irreversible inhibitory effect on the differentiation of cultured embryonic amphibians cells in vitro. Cytological changes and distrubances of cell attachment, and spreading to the culture support occur in parallel. Polykaryons have been noticed in treated cultures.     

Effect of concanavalin A on the development of blastulae in Pleurodeles waltlii (Amphibia, Urodeles)]

The effect of concanavalin A (con A) on Pleurodeles waltlii blastulae was studied by incubating the eggs in presence of lectin. It was found that the protein exercised an inhibitory effect upon morphogenesis. This inhibition was concentration dependent. In certain cases, the inhibitory effect of con A was attenuated by alpha-D-methyl-mannose (0,05 M).     

Effect of periodate oxidation of glycoconjugates of lymphocyte membranes on the immune response in vitro]

Mouse spleen cells treated with sodium periodate for 10 min. at 4 degrees C are stimulated to undergo blastogenesis and to incorporate thymidine. The effect of such treatment on the antibody response in vitro induced by Sheep red blood cells has been evaluated. Periodate-induced proliferation is accompanied by a marked inhibition of the immune response to this antigen. At concentrations leading to mitogenesis, no cytotoxic effect of periodate was observed and treated cells survived well on tissue culture. Cell recoveries from samples treated with periodate at the optimal mitogenic dose, were markedly enhanced when harvested at different days after culturing wheras lower antibody forming cells numbers wereconsistently observed during the culture period.     

Correlation between agglutinability of concanavalin A and nucleic acid synthesis induced by polyoma virus]

We have previously shown the induction of agglutinability by concanavalin A by abortice infection of BHK 21 cells with polyoma virus. In this system, the maximal agglutination occurred simultaneously with the first mitosis. Using inhibitors of macromolecule synthesis in an amitotic system, we showed that this agglutinability was correlated with cell DNA synthesis.     

Effect of methotrexate on glycolysis of leukemia L 1210 cells cultivated in vitro]

Methotrexate, at non lethal doses, alters the glycolysis of leukaemic L 1210 cells. Glucose uptake and lactate excretion are increased but lactate/glucose ratio remains constant. The activity of glycolytic enzymes in the cytoplasm is increased and the level of intracellular ATP is greatly enhanced.     

Effect of the gas phase of cigarette smoke on the rate of sister chromatid exchanges in human lymphocytes in vitro]

A technique of differential staining of chromatids after BudR treatment enabled us to study the influence of the gas phase of cigarette smoke on human lymphocytes. We ascertained that the number of exchanges increased in proportion to the concentration of gas phase extant in the medium. Moreover, the base-line exchange rate was a little higher in smokers than in nonsmokers.     

Effect of hypothalamic crude extract on the utilization of D-[14C]-glucose by the anterior pituitary,in vitro

Resumen Los efectos de extractos crudos de hipotalamo en la utilizacion deD-[¹⁴C]-glucosa por hipófisis anteriores fueram estudiados in vitro en condiciones identicas a aquelas en las cuales los extractos inducen la liberación de hormonas al medio de incubación. Los resultados indican que los extractos hipotalámicos aumentan la producción de¹⁴CO₂ por la hipófisis a partir de glucose y la incorporación de¹⁴C en proteinas del medio de incubación. Los extractos no modificaron la cantidad de¹⁴C glucose utilizada para sintesis de proteinas tissulares.     

Effects of prednisolone and butyrate on agglutinability of HeLa cells by concanavalin A

Cellular and Molecular Life Sciences - Agglutinability by concanavalin A was measured with HeLa65 cells grown with prednisolone or sodium butyrate, 2 compounds that increase the activity of the...     

Effect of some derivatives of naphthalene on aryl hydrocarbon (Benzo[a]pyrene) hydroxylase in vitro

Résumé L'effet du naphthalène et certains de ses dérivés a été étudié in vitro sur l'action de l'aryl hydrocarbon (benzo[a]pyrene) hydroxylase. Les isomères naphthylphosphordicloridat-(1), naphthylphosphordicloridat-(2) et 2-methyl--naphtothioazol inhibent l'enzyme dans les microsomes des rats controles et des rats traités avec le méthylcholanthrène, sans un effet différentiel. Cette inhibition suggère l'occupation du site commun sur l'enzyme. Cependant le naphtalène, le naphthol-(1), le naphthol-(2) le naphthonitrile-(1), le naphthonitrile-(2) ont un effet negligeable sur l'activité enzymatique.     

Further studies on neural tube defects caused by concanavalin A in early chick embryos

Summary Neural tube defects caused by concanavalin A in chick embryos are consequences of change in the cell surface of developing neuroepithelium.This study was supported in part by grants from the Rutgers University Research Council.     

Comparison of the effects of concanavalin A on cell growth and the transport of 3-O-methylglucose in chick embryo fibroblasts

The proliferative capacity of Chick embryo fibroblasts was modified by Con A treatment. Con A decreased the growth of fibroblasts from young embryos (8 days), whereas the lectin stimulated the growth of fibroblasts from older embryos (16 days). This differential effect of Con A did not result from changes in cellular permeability to thymidine, but rather from Con A induced modifications of hexose transport. Changes in hexose transport would cause, as a response, parallel modifications in glycolysis and hence energy charge, which would alter proliferative capacity.