Comptes rendus des seances de l'Academie des sciences. Serie III, Sciences de la vie最新文献

Skin fibroblasts from normal children and two children with a 13q14 deletion retinoblastoma (Rb) were submitted to fractionated doses of gamma radiations. Irradiation reduced the population doublings in normal fibroblasts and the decline was inversely related to the dose. An increase in population doublings was obtained with one of the Rb cell lines. Foci appeared in the irradiated culture of the other Rb donor. It is suggested that fibroblasts from patients with Rb are able to express some phenotypical properties of transformed cells, perhaps related to factors rendering them more susceptible to carcinogens.

An electrochemical method for determination of thiocyanide ions in saliva was established. The procedure involves coupling high performance liquid chromatography (HPLC) on bounded silica gel (in order to eliminate the interference of some ions) with specific electrode. This method is sensitive, precise, rapid and requires only few samples. It offers a great interest in toxicology for the detection of smoking exposure.

The feasibility of gene transfer in differentiated mammalian cells in primary culture, has been worked out in isolated adult rat hepatocytes. The calcium phosphate technique has been applied to the hepatocytes after 3 to 5 days of culture. The DNA of a plasmid carrying the gene S of HBV has been used in the transfection experiments. The transcription of the gene S in the transfected hepatocytes, characterized by the synthesis of the gene product (the surface antigen HBs Ag) has been demonstrated by radioimmunoassay and cytologic visualization by immunofluorescence.

C.T. exploration by N.O.P. in vivo of a Macaca's head is compared with man. The N.O.P. was recognized from many works (E.A.C.). It permitted a biometric approach and very precise morphologic study of the brain and the face. For the first time, it allows comparisons between monkey and man, at different ages.

L-929 cells secrete a neurotrophic factor which is immunologically related to the beta NGF present in the male Mouse submaxillary gland. In order to determine whether L-929 cells also synthesize the alpha and gamma subunits which are associated with the beta NGF in the gland, immunoprecipitations were performed with appropriate antisera. Our results indicate the absence of alpha and gamma subunits in the extracellular medium or in the cell extracts and suggest that the synthesis and secretion of the beta NGF by the L cells does not require these two proteins.

(Met5) enkephalin released from slices of Rat globus pallidus by 30 mM or 50 mM K+ is hydrolysed to the extent of 85% before reaching the incubation medium. When thiorphan and bestatin, two peptidase inhibitors, are added, this inactivation process is completely prevented but the peptide release from tissues is significantly diminished. The latter effect being reversed in the presence of an opioid antagonist, naloxone, in moderate concentration, the existence of an auto-inhibition process regulating enkephalin release is suggested.

A noticeable increase has been observed in the production of the C 3 component of the complement by Rat liver epithelial cells cultured in vitro in the presence of small quantities of supernatant of human blood mononuclear cells cultured for 72 hrs. with phytohemagglutinin. The physicochemical properties suggest that the stimulating factor(s) is(are) protein(s).

Hepatitis A virus (HAV), obtained from human feces collected 3 days after the onset of jaundice, was propagated in human hepatocarcinoma cells (PLC/PRF/5). In the course of 5 passages, it was released into the supernatant without cytopathic effect. Released HAV was propagated after inoculation into PLC/PRF/5 cells. Its biophysical properties (buoyant density in CsCl: 1, 33 g/cm3; sedimentation coefficient: 155 S) were similar to those of the infectious particle present in the cells or in the stools of patients.

Translation of total pancreatic RNA using the rabbit reticulocyte lysate system allowed us to estimate the relative levels of active mRNA coding for a number of secretory proteins in Rats fed high-carbohydrate or high-protein diets. Quantitative synthesis of secretory proteins in isolated pancreatic lobules was also achieved. Protein synthesis in lobules or as the result of active mRNA translation in a cell-free system was found to give similar results either on a qualitative or quantitative standpoint. We were also able to show that the levels of specific mRNA for pancreatic amylase and serine protease zymogens could directly be related to the amount of carbohydrate or protein in the diet. These findings indicate that nutritional regulation of pancreatic enzyme synthesis occurs through the modulation of levels of specific mRNAs in the acinar cell.