Rhône-Poulenc

About: Rhône-Poulenc is a based out in . It is known for research contribution in the topics: Alkyl & Catalysis. The organization has 8909 authors who have published 8934 publications receiving 182241 citations. The organization is also known as: Rhone-Poulenc.

Bax-mediated cell death by the Gax homeoprotein requires mitogen activation but is independent of cell cycle activity

Abstract: Tissues with the highest rates of proliferation typically exhibit the highest frequencies of apoptosis, but the mechanisms that coordinate these processes are largely unknown. The homeodomain protein Gax is down-regulated when quiescent cells are stimulated to proliferate, and constitutive Gax expression inhibits cell proliferation in a p21(WAF/CIP)-dependent manner. To understand how mitogen-induced proliferation influences the apoptotic process, we investigated the effects of deregulated Gax expression on cell viability. Forced Gax expression induced apoptosis in mitogen-activated cultures, but quiescent cultures were resistant to cell death. Though mitogen activation was required for apoptosis, neither the cdk inhibitor p21(WAF/CIP) nor the tumor suppressor p53 was required for Gax-induced cell death. Arrest in G1 or S phases of the cell cycle with chemical inhibitors also did not affect apoptosis, further suggesting that Gax-mediated cell death is independent of cell cycle activity. Forced Gax expression led to Bcl-2 down-regulation and Bax up-regulation in mitogen-activated, but not quiescent cultures. Mouse embryonic fibroblasts homozygous null for the Bax gene were refractive to Gax-induced apoptosis, demonstrating the functional significance of this regulation. These data suggest that the homeostatic balance between cell growth and death can be controlled by mitogen-dependent pathways that circumvent the cell cycle to alter Bcl-2 family protein expression.

Interdiffusion in Cellular Latex Films

Abstract: Latex films have been produced through evaporation of aqueous dispersions containing polymeric particles. These films have a cellular structure: The cell cores are made of hydrophobic polymers, and the cell walls are made of carboxylic monomers that are copolymerized with the core polymers. The mechanical properties of these films are determined by the state of the cell walls. In humid environments, the cell walls take up water and lose their cohesive strength; consequently the films become brittle. The possibility of reinforcing the films through interdiffusion of core polymers across the cell walls was examined. Annealing the films at temperatures where these polymers are mobile produced extensive interdiffusion of low molar mass polymers across the cell walls. This had no effect on the mechanical properties of the films. Annealing at temperatures that caused fragmentation of cell walls produced interdiffusion of high molar mass polymers. At this stage the films became resistant to humidity.

Suriclone: A New Cyclopyrrolone Derivative Recognizing Receptors Labeled by Benzodiazepines in Rat Hippocampus and Cerebellum

Abstract: Suriclone (RP 31,264), like zopiclone (RP 27,267), belongs to the family of cyclopyrrolones and is chemically entirely different from the benzodiazepines (BZDs). However, it possesses a pharmacological profile close to that of the BZDs and proved to be useful in therapeutics as an anxiolytic agent. In the present paper it is shown that suriclone possesses a high affinity for flunitrazepam binding sites and that tritiated suriclone binds specifically with high affinity in rat hippocampus (KD = 0.44 +/- 0.03 nM) and rat cerebellum (KD = 0.53 +/- 0.12 nM). Further, suriclone binding sites are recognized by BZDs or zopiclone, similarly in the two regions. The affinities of four BZD derivatives--nitrazepam, flunitrazepam, diazepam, and chlordiazepoxide--are similar for suriclone and flunitrazepam binding sites. Suriclone binding sites are, like flunitrazepam sites, protected from thermal inactivation by gamma-aminobutyric acid (GABA) (10 microM), but only flunitrazepam binding is enhanced by GABA. It could be postulated from this that suriclone interacts with a subpopulation of receptors that might be modulated differently from flunitrazepam binding sites. Our results indicate that suriclone could be a new probe for investigating the so-called BZD receptors.

Vectorial Production of Interleukin 1 and Interleukin 6 by Rat Sertoli Cells Cultured in a Dual Culture Compartment System

Abstract: The bidirectional production of interleukin-1 (IL-1) and IL-6 by Sertoli cells and its regulation by inflammatory and physiological stimuli has been studied using a dual compartment culture system allowing the study of Sertoli cell apical and basal secretory activities. Another Sertoli cell activity, the vectorial transferrin production was also studied in all culture conditions. A low constitutive IL-1 production appeared equally distributed between both poles, while IL-6 and transferrin constitutive production was predominantly directed apically. Two activators of macrophages, lipopolysaccharides and zymosan, were found to induce marked increases of IL-1 in the compartment where they had been added: basal if added to the lower compartment and vice versa. In contrast, after a basal stimulation, IL-6 production was mainly increased in the upper compartment that corresponds to a Sertoli cell apical flux. In this system, IL-1 and IL-6 levels were not modified by FSH; they were not also affected by residual ...