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Biomedical subjects

E I Lezhnev

Publications and source records attributed to E I Lezhnev.

At least 19 recordsLinked to original sources
PubMed2001

Combined treatment with vitamin B12b and ascorbic acid causes in vitro DNA degradation in tumor cells.

Incubation of Ehrlich ascites carcinoma and HEp-2 human epidermoid laryngeal carcinoma cells with hydroxycobalamin (vitamin B12b) and ascorbic acid induced generation and accumulation of double-stranded DNA fragments (23,000 b.p. and longer) in cells. The same vitamins alone in the same concentrations produced no such effects. DNA degradation in HEp-2 cells caused by long-term (4 h) incubation with 5-25 microM hydroxycobalamin and ascorbic acid (1:10-1:40 molar ratio) at 37 degrees C was comparable with that induced by gamma-irradiation in a dose of 150 Gy at 4 degrees C.

Ascorbic Acid↗
PubMed2001

[DNA degradation and repair in human laryngeal carcinoma HEp-2 cells after combined exposure to vitamin B12b and ascorbic acid].

The formation and accumulation of DNA fragments containing no more than 23,000 pairs of bases were observed under exposure of human larynx epidermoid carcinoma cells (Hep-2) to "chemical nuclease", oxycobalamin (vitamin B12b) and ascorbic acid (vitamin C). The obtained DNA damages were repaired more slowly than those induced by gamma-irradiation in the dose adequate to the level of DNA damages. DNA reparation was not revealed after washing the cells from vitamin B12b and ascorbic acid, and in the course of cell incubation with ascorbic acid. Vitamin B12b and ascorbic acid separately did not induce degradation of DNA. DNA damages induced by "chemical nuclease" action precede the cell death observed later.

Ascorbic Acid↗
PubMed2001

[Primary culture of epithelial secretory cells from venom gland of the common adder Vipera berus].

A primary culture of epithelial secretory cells from the venom gland of Vipera berus was obtained. The cells adhered to collagen 1 and to a mixture of adhesion proteins (Matrigel), proliferated and retained the features of differentiation. Electron microscopy demonstrated the presence of all ultrastructures typical of these cells in vivo, a full complex of intercellular junctions, and cellular membrane polarity. The immunohistochemistry confirmed the capacity of secretory cells to synthesize venom in culture. We have studied the role of carbochole, an agonist of M-cholinoreceptor, in the initiation of the secretory cycle in cells in vitro. We propose that M-cholinoreceptors may play an important role in the initiation of the secretory cycle in vivo.

Animals↗
PubMed2000

Functional activity of hepatocytes in tissue fragments in a new bioreactor biological artificial liver.

Functional activity of hepatocytes in a new bioreactor designed for culturing of liver tissue fragments under perfusion conditions was tested. Specific hepatic functions such as ammonium detoxification, urea and protein synthesis, and P-450-dependent metabolism of p-nitroanisole were maintained for 1.5 days. The bioreactor can be used as a bioartificial liver support apparatus.

Animals↗
PubMed2000

Combined vitamins Bl2b and C induce the glutathione depletion and the death of epidermoid human larynx carcinoma cells HEp-2.

The combination of hydroxocobalamin (vitamin B12b) and ascorbic acid (vitamin C) can cause the death of tumor cells at the concentrations of the components at which they are nontoxic when administered separately. This cytotoxic action on epidermoid human larynx carcinoma cells HEp-2 in vitro is shown to be due to the hydrogen peroxide generated by the combination of vitamins B12b and C. The drop in the glutathione level preceding cell death was found to be the result of combined action of the vitamins. It is supposed that the induction of cell death by combined action of vitamins B12b and C is connected to the damage of the cell redox system.

Ascorbic Acid↗
PubMed2000

[Migration of fibroblasts into heart valve leaflet tissue in vitro].

Heart valve allografts are widely used for surgical treatment of the heart. In recent years a new field of research has emerged dealing with allograft modification by cells of recipient by means of tissue engineering. This method involves culturing fibroblasts and endothelial cells, using recipient tissue, followed by introduction of the fibroblasts into tissues of allograft and coating its surface by the endothelial cells. This modification is expected to ensure the structural maintenance of implanted tissues and to reduce its thrombogenecity. This procedure may promote the allograft adhering to the recipient tissues, thus prolonging the terms of the valve normal functioning after implantations. For this purpose, methods of luminescent microscopy are suggested using double staining of tissue with fluorescent dyes Hoechst 33,342 and ethidium bromide, or with fluorescein diacetate and ethidium bromide. Experimental results are presented indicative of fibroblast migration from the surface to the human heart valve leaflets.

Animals↗
PubMed1997

[The cultivation of fragments of the parotid venom-secreting gland in the common adder (Vipera berus)].

The primary culture of the Vipera berus poison-secretory parotid gland has been obtained. The morphology of the intact secretory epithelium and epithelial cells cultured in different conditions has been examined by light and electron microscopy. The secretory epithelium cells were able to survive in the cultural medium and to adapt to in vitro conditions maintaining their nearly normal ultrastructure corresponding to the stage of active poison secretion commonly observed in epithelial cells of the native gland.

Animals↗
PubMed1993

[The oxidative phosphorylation system of BHK-21 cells in suspension cultivation].

The state of the oxidative phosphorylation system in intact and digitonin-treated BHK-21 cells in the lag-, logarithmic and stationary growth phases has been studied. It is shown that during the growth of cell culture the rates of oxygen uptake and the extent of coupling of oxidation and phosphorylation change significantly.

Animals↗
PubMed1991

[The proliferative characteristics of cells in culture during perfusion of the medium].

The proliferation of Chinese hamster fibroblasts (CHF) and NIH 3T3 cells was studied at different flow rates immediately above the cells. It is shown that there is a limiting density of saturation of the perfused culture that accounts for 1.7 x 10(6) - 2.0 x 10(6) cells/cm2 for NIH 3T3 cells, and for 6 x 10(6) - 7 x 10(6) cells/cm2 for CHF. The growth curves and the distribution of cells with respect to the phases of the cell cycle during cultivation with and without perfusion are presented. Based on the results obtained it is assumed that the limit of saturation density of perfused CHF culture is due to the mass transfer of the growth-inhibiting metabolites inside the multilayer structures. The assumption seems to hold true for NIH 3T3 cells, too, even though the multilayer character of growth of this culture is less pronounced than in CHF.

Animals↗
PubMed1990

[A flow diffusion chamber for research on cells in culture].

A flow diffusion chamber designed for studying cells and tissues in culture is described. The chamber contains a plate with a great number of isolated holes, which enables one to perform the cultivation of cells at different distances from the porous membrane separating the cells from the perfused medium. An individual porous membrane can be placed above each hole. Evidence for the selective permeability of domestic membranes under the conditions of cell culture in chamber is presented. The chamber makes possible a simultaneous cultivation of a great number of various cultures with different conditions of mass exchange with common perfused medium, which contributes to intensification of studies.

Animals↗
PubMed1989

[Regulation of the synthesis of total cellular proteins and monoclonal antibodies in a hybridoma cell culture].

A study was made of the regulation of total protein synthesis in cells of the mouse hybridoma producing monoclonal antibodies (McAb) against lambda phage, and in the course of hybridoma growth and at the change of fetal bovine serum (FBS) concentration. FBS strictly affected proliferation of hybridoma cells, the specific production of McAb per cell being unchanged. The rate of total cellular protein synthesis does depend on FBS concentration in the medium, whereas the rates of protein degradation and secretion do not. Evidence is presented that the reduction in the protein-synthesis rate, after the removal of FBS from the medium, is caused by a coordinated decrease in both the rate of protein synthesis initiation and the rates of polypeptide chain elongation and translation termination. The decrease in the protein synthesis rate at the stationary phase of cell growth was shown to be related to the three main factors: 1) a 15-25% decrease in ribosome content per cell; 2) a two-fold decrease of the ribosome portion involved in mRNA translation; 3) a 5 to 15% decrease in the rate of mRNA translation. Evidence is presented that the decrease in the portion of mRNA translating ribosomes is due to the decrease in the rate of protein synthesis initiation.

Animals↗
PubMed1988

[Protein metabolism during the growth of hybridoma cells].

Protein metabolism during the growth of mouse hybridoma, producing monoclonal antibodies to phage lambda has been studied. The rate of protein accumulation Va at any time of growth was equal to that of protein synthesis Vs minus the degradative rate Vd and protein secretion rate Vsecr (Vn = Vs--Vd--Vsecr). Cellular protein metabolism was described in terms of the relationship 6.3% hr = 8.1%/hr--1%/hr for the middle of exponential growth phase, and in terms of the relationship 1.4%/hr = 2.9%/hr = 0.8%/hr--0.7%/hr for the early stationary phase. The results obtained enabled us to conclude that the synthesis of cellular proteins may be the main process regulating the protein metabolism during hybridoma cell growth.

Animals↗
PubMed1986

[Effect of nutrient medium perfusion on the secretory activity of rat hepatocytes and pancreatic islet cells].

The data are reported on albumin secretion by rat hepatocytes and insulin secretion by pancreatic beta-cells of newborn rats during cell cultivation on flat synthetic membrane in conditions of continuous medium perfusion. Albumin and insulin secretion by the appropriate cultures was higher in continuous medium perfusion than in the control. Enhanced sensitivity of pancreatic beta-cells to glucose, as compared to the control was revealed. It is concluded that continuous medium perfusion of hepatocytes and pancreatic beta-cells in the primary culture had a favourable effect on albumin and insulin secretion by the appropriate cultures.

Albumins↗
PubMed1985

Low pH value of pericellular medium as a factor limiting cell proliferation in dense cultures.

An attempt was made to determine the role of metabolic acidification of pericellular medium in regulating cell proliferation. A method of measuring the pH of pericellular medium at a distance exceeding a Debye radius of 5-10 A from the cell surface (pHp) was developed. The values of pHp and pH measured in the medium at a distance of greater than 1 cm from cells (pHm) were found to differ, depending on the cell population density. At a density of at least 7 X 10(5) cells/cm2 (maximum saturation density) and at pHm 7.4-7.6, pHp reached a value of approximately 6.5. It was found that pHm 6.5 was unfavorable for cell proliferation in sparse cultures, where pHm and pHp were equal. Based on these findings, low pHp as revealed in the present work using dense cultures at optimal pHm can be considered to be a limiting factor for cell multiplication.

Animals↗
PubMed1985

[Growth of a cell culture on porous capillaries].

The growth of BHK-21 culture cells on the outer surface and in the clear space of capillaries made of phenylone or polyacrylnitrile was studied. The cultivation of cells in the clear space of the capillary extends their survival time and outlines possible ways of continuous cultivation of tissue cells which are cultivated in the attached state.

Acrylic Resins↗
PubMed1984

[Fibroblast adhesion to glass and the dynamics of pH change in the medium in the pericellular space].

A study was made of dynamics of pH changes in the pericellular space of the Chinese hamster fibroblasts after the completion of cell sedimentation in three media. With the first medium, the cells were spread over the glass, with the second one they were attached to the glass without spreading and with the third medium the cells were not attached to the glass at all. The pH value of the medium surrounding the cells decreased, mainly, within the first 6 hours after sedimentation was completed, this depended on the cell population density on the glass surface. The outlook of this dependence was different for the three media. Based on the analysis of the results obtained it is concluded that the attachment of cells to glass may lead to the increased efflux of acid metabolic products from the cell.

Animals↗