Comptes rendus des seances de l'Academie des sciences. Serie D, Sciences naturelles最新文献

In contrast to 8-MOP photoaddition on DNA, the renaturation capacity of heat or alkali denatured DNA treated with 3-CPs is absent. This shows that DNA interstrand cross-links are not produced by 3-CPs photoaddition even by a dose which leads to 10(-5) survivors. At equimolar concentrations of 3-CPs or 8-MOP (5 x 10(-4) M) and a dose of 10 kJ.m-2 of 365 nm radiation, 1 molecule of 3-CPs for 4 x 10(3) nucleotides and 1 molecules of 8-MOP for 9 x 10(3) nucleotides are fixed in vivo. Since wild type cells are about 4 times more sensitive to 8-MOP than to 3-CPs photoaddition, it implies that cross-links are important in genotoxicity and that monoadditions are more easily repaired than cross-links.

The collagen secreted by dermal fibroblast cell cultures, previously labelled with 3H-proline, was extracted and purified by carboxymethyl cellulose. The ratio of hydroxyproline to proline showed that the collagen produced by cell cultures may be under-hydroxylated in comparison to the ratio observed in the types of collagen extracted from human skin. Then, it is concluded that it is not sufficient to determine only the hydroxyproline content for a collagen biosynthesis study in cell cultures. This low hydroxyproline content may explain the rapid catabolism of a part os newly synthetized collagen in vitro.

The authors have measured the effects of methoxy-2 ethanol and derivatives or analogs on adjuvant arthritis in Rat, and the activity of methoxy-2 ethanol on humoral responsiveness to antigenic stimuli in Rat. Only methoxy-2 ethanol,1,2-dimethoxyethane and 1-methoxy 2 ethoxy ethane out of 13 tested derivatives, have an inhibitory activity on adjuvant arthritis. Methoxy-2 ethanol induces a significant depression of antibody production after immune stimuli and a significant effect on rejection of the skin graft. Although these results are of interest, toxicity of methoxy-2 ethanol will be a limiting factor for therapeutic use.

Morphological and autoradiographic data give evidence that secretion take place at the odontoblast process level according to a lateral axis, perpendicular to the maturation axis of the predentine. Induced modifications with vinblastine sulphate emphasize the importance of the pericellular space (150--200 nm) while the disorganization of the collagen fiber arrangement suggests the presence of flows. We propose an hypothesis which connects all these facts.

Using the indirect immunofluorescence technique and an antiserum against the specific beta subunit of human TSH, selective immunocytochemical staining was localized in a cell population of the pars distalis of the monkey Macaca irus. These thyrotropic cells, which were positive to aldehyde fuchsin, Alcian blue, and PAS, were localized on the one hand in the ventro-medial zone of the pars distalis, especially alongside the large vessels of this region, and on the other in the zona tuberalis, i. e. at the bottom of the pars tuberalis. Some cells, sparsely distributed, were seen in the posterior part of the lateral lobes of the pars distalis, in the vicinity of the pars intermedia. No thyrotropic cells were encountered in pars tuberalis. Pars intermedia and posterior lobe contained no cells immunoreactive to beta-hTSH. In females, the thyrotropic cells were more numerous and larger than in males. Generally the thyrotropic cells were round or oval in shape, sometimes they were polygonal.

Chromosome studies were performed by EBV positive African Burkitt lymphoma cell lines. Variant translocations were found in 4 cases: two with t(2;8) (p12;q23 ou 24) and two with t(8;22) (q23 or 24;q11). Identical translocations were observed in EBV positive or negative non-african lymphomas or Burkitt type leukemia. These results show the uniqueness of Burkitt lymphoma leukemia and stress the importance of chromosome 8 rearrangement in this tumor.

Substance P (SP) immunoreactive structures were localized by immunofluorescence technique within the central nervous system of human fetuses (12, 15, 19 and 24 weeks old). Specificity of the anti-SP serum was established by immunocytology and radio-immunology. A wide distribution of SP positive structures (pericaryons and/or fibres) was found in brain, spinal cord and dorsal root ganglia. Mesencephalon, pons and dorsal horns of the spinal cord showed very intense fluorescence. The preliminary observations are the first report concerning SP ontogeny in the Human central nervous system. However, it was difficult to ascribe a significance to this neuropeptide during fetal life.

Treatment of Chick embryo fibroblasts (CEF) with 5-bromodeoxyuridine considerably increases the expression on the cell membrane of a cellular antigen related to an antigen specific to Chick embryo erythrocytes, present on the envelope of avian sarcoma oncoviruses produced by CEF.