Isolation, study of activity, and characteristics of an immunosuppressive liver factor causing apoptosis of EL-4 thymoma cells in vitro

Immunosuppressive factor (ISFnp) which inhibits proliferation and viability of thymoma EL-4 cells was isolated from mouse liver. The testing procedure based on the biotransformation of MTT-tetrazolium by mitochondrial enzymes of viable cells allowed us to purify this factor as individual peak of protein, that allowed to obtain polyclonal rabbit antibodies to this factor. By the methods of double immunodiffusion, gel-filtration and SDS-PAGE with subsequent immunoblotting we shown that this factor specifically localized in liver and consists two subunits of 40 and 42 kDa which form dimers with apparent M(r) about 70-80 kDa. This factor induced olygonucleosomal DNA cleavage in EL-4 cells in vitro similar to dexamethasone-induced DNA-degradation in thymocytes. This cleavage preceded to lysis of EL-4 cells assessed by 51Cr-release, that strongly suggested an involvement of apoptosis in cell death mechanism. ISFnp strongly inhibited blast-transformation and proliferation in MLC-responses to mutant MHC class 2 molecule. This effect was not due to deletion of allo-reactive clones, because removing of this factor from MLC cultures treated with one for 4 days resulted in blast-transformation without any reduction of the number of viable cells as well as their capacity for secondary responses to the same antigen as compared with control cultures.     

Theory of the swelling of porous materials

Equations describing the kinetics of the swelling of fissionable materials are derived for a model presupposing the existence of pores in the fissionable material. The operating conditions preceding the beginning of swelling are considered in greater detail. The concept of the time when swelling begins is introduced. Expressions which relate the time of initial swelling to the diffusion coefficient of gaseous fragments, the material's strength characteristics, the temperature, the size and concentration of pores, and the rate at which gaseous fragments are generated are derived for a number of cases.In conclusion, he authors extend their thanks to L. P. Semenov for the valuable discussion concerning a number of problems. The authors are also grateful to O. D. Kazachkovskii, S. T. Konobeevskii, and A, I. Leipunskii for the discussion of the results and many valuable remarks.     

Contribution to the theory of radiation effects on some properties of graphite

A substantial change occurs in several of the properties of graphite subjected to in-pile irradiation. These changes are the result of damage to the crystal lattice structure of the graphite. The present article presents a calculation of the change in lattice constant and internal energy of a unit volume of a crystal of graphite containing Frenkel defect-type imperfections. The results of the calculation are compared with experimental data.In conclusion, the author would like to avail himself of this opportunity to express his profound gratitude to A. I. Leipunskii for his kind attention to the progress of the work and the numerous useful comments advanced in discussions of the results.