No abstract

The RNA synthesis of human leukemic leukocytes and phytohemagglutinin-stimulated lymphocytes is markedly reduced by administration of a low-molecular-weight nonhistone peptide factor from calf thymus. Treatment with the factor strongly inhibits hemoglobin production and globin mRNA transcription in dimethyl sulfoxide-stimulated Friend cells without appreciably modifying the rate of cell growth. Evidence for specificity of these effects is provided by the lack of action of the factor on both growth rate and RNA synthesis of a number of nondifferentiating cell lines from various animal species. After removal of the compound, both human lymphocytes and Friend cells can be stimjK'a&ed by phytohemagglutinin and by dimethyl sulfoxide, respectively, ruling out any toxic effect.We have previously isolated, from aqueous extracts of calf thymus, an active factor, which has been partially purified by DEAE-cellulose and Dowex 50WX2 chromatography and characterized as a peptide of less than 5000 molecular weight (1). This factor causes a strong inhibition of DNA-directed (1) or chromatin-directed (2) RNA polymerase reactions in vitro.

No abstract

The Free Form Deformation method was applied to an S-duct geometry to reduce total pressure losses and flow distortion. The deformation method was coupled with a multiobjective genetic algorithm to optimize the shape of a diffusing S-duct, which was numerically and experimentally investigated in previous works. During the optimization process, 200 deformed shapes were tested with steady-state CFD simulations and the performances were evaluated both in terms of total pressure losses and swirl angle at the outlet. It was obtained a Pareto front with a maximum total pressure losses reduction of 20% and a maximum swirl reduction of 10%. The two extreme points of the Pareto front were further investigated by unsteady Detached Eddy Simulations to assess also the impact of the optimization on the flow instability. Surprisingly, one of the solutions showed stable and stationary vortical structures. This is in strong contrast with the previous investigations of the flow field time history of the baseline configuration, which outlined strong oscillations of the flow field combined with a high increase of the distortion parameters in comparison with the time-averaged flow field.

A calf thymus peptide fraction controlling DNA and chromatin template has been purified by DNA-cellulose and Dowex 50 WX2 chromatography and its amino acid composition determined. The active peptide fraction can be extracted in high pH buffer from calf thymus native chromatin previously deproteinized by chloroform-isamyl alcohol and phenol. These data demonstrate that the thymic peptide(s) is (are) a chromatin protein constituent strongly linked to DNA. The specificity in association of the peptide(s) to DNA has also been considered.