Biomedical subjects

C Poujeol

Publications and source records attributed to C Poujeol.

21 records · Page 2Linked to original sources

PubMed1985

Development of ionic channels during mouse neuronal differentiation.

Using a mouse embryonal teratocarcinoma (E.C.) cell line, it was possible to follow the sequence of development of ionic channels during neuronal differentiation, with patch-clamp techniques. 1003 E.C. cells were induced to differentiate into neurons by culturing them in defined medium without foetal calf serum (DARMON et al., 1981). Non-differentiated cells were not excitable and presented mainly 2 types of K+ channels: a Ca2+ activated K+ channel (220 pS in symmetrical K+) and a delayed rectifier (30 pS in symmetrical K+). When the cells start to grow neurites, a low threshold calcium current can be recorded, only if the cell is held at hyperpolarized potentials (-70 to -80 mV). Fully differentiated cells with long neurites presented a complete repertoire of ionic channels: voltage dependent Na+ and Ca2+ channels, Ca2+ activated K+ channel and K+ delayed rectifier.

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PubMed1975

[Comparative dose-effect relationship of a tuberculin standard on guinea pig sensitivity, using living and dead tuberculosis bacilli].

The sensitization of guinea pigs utilized for tuberculin titration may be obtained by a BCG primo-vaccination followed by an inoculation of live, virulent Myc. tuberculosis. This method, which results in a sub-evolutive form of tuberculosis, gives a satisfactory sensitization level but has the disadvantage of utilizing animals which are germ carriers and therefore dangerous. A method has been tested employing killed germs (Jamaica strain) coated with Freund's complete adjuvant H37Ra which utilizes animals presenting no danger in handling. The results of 105 titrations made on 453 guinea pigs during two years show that the reactions obtained are clear, easy to read and remain stable over a long period (F equals 0.1). The comparison of values thus obtained shows that in the case of killed bacilli in relation to live bacilli: the mean dimensions of the reaction with 5, 10 and 20 IU are significantly more important (P is less than 0.0001) and the dose-response slope is significantly steeper (P is less than 0.01) which offers more precise results. Sensitization by killed germs therefore offers the double advantage of handling non-dangerous animals and obtaining results which are more precise and easier to read.

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PubMedDate not supplied

Both upstream and intragenic sequences of the human neurofilament light gene direct expression of lacZ in neurons of transgenic mouse embryos.

Initial expression of the neurofilament light gene coincides with the appearance of postmitotic neurons. To investigate the molecular mechanisms involved in neuron-specific gene expression during embryogenesis, we generated transgenic mice carrying various regions of the human neurofilament light gene (hNF-L) fused to the lacZ reporter gene. We found that 2.3 or 0.3 kb of the hNF-L promoter region directs expression of lacZ in neurons of transgenic embryos. Addition of 1.8 kb hNF-L intragenic sequences (IS) enlarges the neuronal pattern of transgene expression. The 2.3-kb hNF-L promote lacZ-IS construct contains all regulatory elements essential for both spatial and temporal expression of the hNF-L gene during embryogenesis and in the adult. The use of a heterologous promoter demonstrated that the 1.8-kb hNF-L intragenic sequences are sufficient to direct the expression of lacZ in a NF-L-specific manner both temporally and spatially during development and in the adult. We conclude that these hNF-L intragenic sequences contain cis-acting DNA regulatory elements that specify neuronal expression. Taken together, these results show that the neurofilament light gene contains separate upstream and intragenic elements, each of which directs lacZ expression in embryonic neurons.

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