The effect of irradiation on the antibody enhancing helper T cells

Helper T cells specific for sheep erythrocytes were generated in lethally irradiated mice. The helper effect exerted by these cells was determined in vitro in spleen cell cultures. Irradiation of the helper cells in vivo or in vitro with 1-9 Gy resulted in a bimodal relation between radiation dose and helper effect when measured either immediately or 6 hours after irradiation. The dose-effect curve became nearly linear when tested 20 hours after irradiation. These results indicated that the helper population consisted of about 80 per cent of cells inactivated shortly after irradiation, possibly due to interphase death, and a second type showing a more retarded cell death. The latter cells were able to exert a helper function during the interval between irradiation and cell death.     

Action of aurantin on the chromosomal structure of continuous cultures of human amniotic cells (line A-1)]

When transplantable cultures of human amniotic cells, line A-1 were treated with auranthin in concentrations of 0.1 and 0.5 gamma/ml for 48 hours of their growth, the chromosomes in the methaphase proved to be not evently spiralized longitudinally and acquired the appearance of segmented structures. All the chromosomes in the set possessed the capacity for such segmentation. It was most pronounced near the centromers and at the ends of the meta- and submetacentric chromosomes. The acrocentric chromosomes were segmented longitudinally more evenly. Loose segments of the chromosomes most probably corresponded to the areas, in which auranthin binding with DNA occurred. The effect of auranthin on differentiation of the chromosomes longitudinally may be used, as it was indicated for actnomycin D, in identification of homological chromosomes in the karyotype, as well as in studies on the temporal sequence of DNA synthesis in the chromosomes.