[The isolation and phenotypic characteristics of heat-resistant cells from the Chinese hamster CHO-K1 line]. / Poluchenie i fenotipicheskie osobennosti termorezistentnykh kletok kitaiskogo khomiachka linii CHO-K1.

By sequential selection for a resistance to a short-term heating at 45 degrees C, two independent clones, CHSR5 and CHSR6, have been isolated from ovarian cells of the Chinese hamster (CHO-K1). A subline CHO-A40, capable of proliferation at 40 degrees C, has been obtained as mass culture by culturing CHO-K1 cells for 2 months at 40 degrees C. The lines obtained have no cross-resistance to the temperature used in their selection: the CHSR5 and CHSR6 cells are not capable of reproduction at 40 degrees C, while the CHO cells do not survive over a 60 min heating at 45 degrees C. This bears evidence that mechanisms, underlying the cell resistance under different thermal regimens used, may be different. The heat resistant sublines maintain their heat resistance for 6 months of cultivation at 37 degrees C. The acquisition of heat resistance by cells correlates with their high primary resistance, and with their resistance to colchicine and actinomycin D.

[The temperature dependence of protein kinase A and C activity in variant mouse neuroblastoma cells differing genetically in their heat resistance]. / Temperaturnaia zavisimost' aktivnosti proteinkinaz A i C u variantov kletok neiroblastomy myshi, geneticheski razlichaiushchikhsia po teploustoichivosti.

The ability of the mouse neuroblastoma cell line NTR to proliferate at 40 degrees C correlates with the position of the temperature optimum of protein kinases A and C activities in the region of higher temperatures compared to those for cells of the original line N18AI, and with higher thermostability of protein kinase A after its heating at various elevated temperatures. The found changes in protein kinases A and C in the cells of NTR line mean that the selection of variants, capable of growing at elevated temperatures, is accompanied with conformational protein changes.

[Changes in the surface and activation of circulating leukocytes after autologous transfusion of UV-irradiated blood]. / Izmeneniia poverkhnosti i aktivatsii tsirkuliruiushchikh leikotsitov pri autotransfuziiakh UF-obluchennoi krovi.

Under study was the dynamics of functional properties of leukocytes of healthy people and patients after UV-irradiation of their blood, mixing the UV-irradiated and non-irradiated blood. It was shown that UV-irradiation and mixing the irradiated and non-irradiated blood facilitated the liberation of bactericidal cation proteins of leukocytes, higher expression of membrane receptors, growth factors, activation of reparation of DNA after its injury by gamma-rays. It proves the role of immediate activation of leukocytes of the circulating blood in trigger mechanisms of effects of autotransfusion of UV-irradiated blood.

[Synthesis and secretion of recombinant protein--the product of v-sis oncogene in Saccharomyces cerevisiae cells]. / Sintez i sekretsiia rekombinantnogo belka--produkta onkogena v-sis v kletkakh drozhzhei Saccharomyces cerevisiae.

The recombinant plasmid DNA YEp secl-v-sis was constructed. This plasmid was able to code for the synthesis and secretion into the cultural medium of the protein-product of oncogene v-sis. Transcription, copy number and stability of the plasmid DNA were studied under the conditions of galactose induction. The v-sis protein was determined by gel electrophoresis and immunoblotting methods and assayed for cell-proliferation activity in the mammalian cell culture.

[General and primary thermoresistance in genetically differing variants of murine neuroblastoma]. / Obshchaia i pervichnaia teploustoichivost' u geneticheski razlichaiushchikhsia variantov neiroblastomy myshi.

General and primary thermoresistance of mouse neuroblastoma clonal cell lines derived from N18A subline was studied: the N18A1 clonal cell line was not treated by heat, the NTR1 was obtained by one-step selection for resistance to the long action of the temperature 40 degrees C, the NHSR1 was obtained by multistep selection for resistance to short-time treatment at 44 degrees C. The NHSR1 clonal line was shown to have higher general and primary thermoresistance by comparison with that of N18A1 cells. The NTR1 cell line, capable of unlimited proliferation at 40 degrees C, did not differ in general resistance but displayed a slower primary resistance compared to that in the N18A1 cells. Cells of all the three clones were found to be capable of temporary increasing in primary thermoresistance, i.e. hardening. A possible contribution of the primary resistance into the general one in cells of all the selected clones has been discussed.

[Expression of heat-shock proteins in neuroblastoma cells differing genetically in thermal sensitivity]. / Ekspressiia belkov teplovogo shoka v kletkakh neiroblastomy, geneticheski razlichaiushchikhsia po termochuvstvitel'nosti.

Electrophoretic analysis of cell proteins of 3 mouse neuroblastoma strains differing in thermostability has shown that a distinctive feature of one of the strains (stable to the action of temperature at 44 degrees C) is the accumulation under normal conditions (37 degrees C) of heat shock protein with the molecular mass of 70 kD. Such accumulation of the specific protein does not take place in cells of the thermosensitive strain, stable to temperature of 40 degrees C.

[Phenotypic characteristics of heat-resistant murine neuroblastoma cells]. / Osobennosti fenotipa teploustoichivykh kletok neiroblastomy myshi.

One-step selection of murine neuroblastoma (N18TG2 cell line) for the resistance to injuring action of higher temperature resulted in obtaining cell line NTR1 stably capable of proliferating at 40 degrees C. The thermoresistance is shown to be coupled with the changes in some phenotypic features of NTR1 cells: the multiplication rate, saturation density of cells, morphological features, inducibility of long neurite-like processes and adhesion. A possible significance of plasma membrane changes in genetically stable thermoresistance of NTR1 neuroblastoma cells is discussed.

[Turnover of potential-dependent ion channels in the membrane of neuroblastoma cells studied using the protein synthesis inhibitor cycloheximide]. / Issledovanie vremeni obmena potentsialzavisimykh ionnykh kanalov v membrane kletok neiroblastomy s pomoshch'iu ingibitora belkovogo sinteza tsiklogeksimida.

The influence of cycloheximide on currents through sodium and potassium channels in dialysed neuroblastoma cells of clone N18A-1 has been studied under voltage clamp conditions. When cells are incubated with cycloheximide, the conductance of sodium decreases, whereas that of potassium changes only slightly, if at all. The cycloheximide concentration, at which sodium conductance is reduced by 50% during 24 hours incubation, was about 0.5 microgram/ml. The half-time of inhibition at the concentration of 15 microgram/ml was about 9 hours, with the time of 50% inhibition of sodium being more complex than single exponential. The density of sodium channels in control and after the maximal inhibition was estimated to be about 25 and 2.2 micron-2, respectively. The sodium-potassium selectivity and the gating mechanism parameters were shown to be unchanged following cycloheximide treatment.

[Ionic currents of neuroblastoma clone N18 A-1 cultured cells under potassium fluoride and phosphate intracellular dialysis]. / Ionnye toki kul'tiviruemykh kletok neiroblastomy klona N18 A-1 v usloviiakh vnutrikletochnogo dializa ftoridom i fosfatom kaliia.

Ionic currents of cells of neuroblastoma clone N18 A-1 was studied under conditions when the internal medium was placed for artificial fluoride or phosphate solutions. The specific membrane leakage resistance was measured to be 8.1 +/- 2.6 kOhm.cm2 and 1.3 +/- 0.3 Kohm.cm2, respectively. The presence of usual sodium and tetraethylammonium sensitive potassium channels is demonstrated. Potassium conductance is shown to amount to 0.25--0.025 of sodium conductance. Dialysis of the cells by phosphate solutions induces a slow outward current, which is not inhibited by tetraethylammonium ions.