Site-directed mutagenesis in the uracil-repair system. Preparation of mutated forms of human alpha 2 interferon

The mutant forms of human IFN-alpha 2 gene are obtained by oligonucleotide-directed mutagenesis with the use of uracil-repair system. To intensify the process the procedure of the uracil-containing DNA template preparation is modified. It was determined that when mutagenesis is performed in the uracil-repair system the yield of the process depends on the mutant DNA-strand in vitro synthesis efficiency. It is shown that the stability of the 5'-end primer-template complex and the level of the endogenic primers elongation are the basis factors, that determine induction mutations.     

Kemantane pharmacokinetics in rats

Pharmacokinetics of novel immunostimulating drug kamantane was studied by using gas-liquid chromatography in experiments on rats. It was found that kemantane biotransformed rapidly after oral administration with the forming of active metabolite. Kemantane and its metabolites are distributed rapidly from the blood to organs. The drug is eliminated from the organism of rats as metabolite.     

Regulation of apolipoprotein expression]

Recent data and concepts on the structure and functioning of apolipoprotein genes as well as on the role of hereditary factors in pathogenesis of atherosclerosis are reviewed. The most important variants of inherited disorders in the system of apolipoproteins promoting the development of atherosclerosis are considered. Special attention is paid to the RFLP of apolipoprotein genes which serves as a peculiar genetic background, increasing probability of the atherosclerosis development in certain individuals.     

Neurospecific and neuron-specific enolase levels in human nerve tissue at early stages of embryogenesis

Neurospecific and neuro-nonspecific isozymes of glycolytic enzyme enolase known to be molecular markers of neuronal and glial cells respectively were isolated from human brain. Using immunoenzyme assay, the content of these proteins was measured in the brain of 7-13-week human embryos and adult subjects. The content of both isoenzymes gradually increases attaining constant level in 10-13-week embryos. Relative content of neuro-nonspecific enolase in the brain of 10-13-week embryos is 1 1/2 times higher than that in adults, whereas the content of neurospecific enolase amounts only to 2% of its level in the adult brain.     

Effect of rad 54 mutation on the ability of Saccharomyces cerevisiae cells to recover from radiation and thermal injury

The diploid cells of Saccharomyces cerevisiae carrying rad 54 homozygous mutation do not exhibit an ability for any considerable "rapid" postirradiation and post-hyperthermic recovery. A pretreatment with high temperature (50 degrees C) increases the radiation response of mutant cells. Survival of cells overheated before gamma-irradiation is increased by keeping them in water for 2-6 h at 28 degrees C, while the corresponding value of survival for cells treated by each of the factors delivered separately remains constant in these conditions.     

Content of iron and copper in the nuclei and induction of pH 9-labile lesions in L5178Y sublines inversely cross-sensitive to H2O2 and x-rays

Cells from the L5178Y murine lymphoma subline LY-R are twice as resistent to killing by ionizing radiation than the subline LY-S. In contrast, LY-R cells are more sensitive to killing by H₂O₂, the effect being more pronounced at 37 °C than 0 °C. Initial DNA damage after H₂O₂ treatment (both temperatures, 5 min) has been estimated by the comet assay (single-cell gel electrophoresis) and fluorescent halo technique. According to both methods, the initial damage is significantly higher in LY-R cells, particularly that inflicted at O °C. Differences between DNA unwinding and rewinding abilities at pH 9 and 6.9 (estimated by the fluorescent halo technique) point to a considerable difference in pH-9-labile damage between the sublines, as observed previously for x-irradiated cells (Kapiszewska et al. 1992). In contrast to findings with x-irradiated cells, however, after H₂O₂ treatment this damage is more extensive in LY-R cells than in LY-S cells. Thus, the initial pH-9-labile damage corresponds to the pattern of sensitivity to H₂O₂ and x-rays. We suggest that this is caused by different proportions of cuprous and ferric ions found in the nuclei of LY sublines and by the different ability of these ions to react with H₂O₂ and water radiolysis products. The copper/iron ratio in the nucleus is 1.31 in LY-R cells and 4.84 in LY-S cells.     

Patterns in the structural homeostasis of cardiomyocytes

Results of quantitative analysis of the ultrastructura organization (UO) of animal (rabbit, rat, dog) and human cardiomyocytes carried out by means of the point method are presented. A number of stereometric constants which provide structural cardiomyocyte homeostasis (SCH) were revealed: the sum total mitochondrial (MT) and myofibril (MF) volume is a constant value- a "cardiomyocytic constant" (Vmt + Vmf=Kcm); the total growth of MT and MF volumes in different functional states is equal to "0" (dVmt + dVmf=0); adaptational MT and MF rearrangement takes place during an interval of 11% of the volume (deltaVmt=deltaVmf=11 percent; the SCH is maintained by the changes of the UO within the limits of the law of "constancy of volume interrelations" (80; 10; 10), according to which 80 percent of the volume falls on Kcm, 10 percent of the remaining organellae and cell inclusions (Vi) and 10 percent on the plasma cell (Vpl). The assumption on a possibility of universality of the stereometric constants is suggested.