[New Mn-chelates are radioprotectors and antioxidants for cells in vitro]. / Novye khelaty margantsa -- radioprotektory i antioksidanty dlia kletok in vitro.

Earlier we have synthesized new Mn-chelates (Mn-compexes of ethyl ethers of salicyliden-D, L-tyrosine, -gamma-amino butyric acid and -D, L-tryptophan) bearing several free functional groups. The radioprotective and antioxidant activity of these compounds were tested on the secondary cultures of chick embryo cells. To this end the cells in vitro were gamma-irradiated with 60Co at the doses 40 and 60 Gy or treated with H2O2 at the concentration 3 mmol/l, the new Mn-chelates were added into the cultures, and the number of survived cells was determined in 24 hours. It was revealed that all the new Mn-chelates at micromolar concentrations (from 40 to 10 mumol/l) but not their precursors (Mn-acetate and ethyl ethers of salicyliden-aminoacids) effectively protect the cells from lethal effect of both gamma-irradiation and H2O2. Mn-chelates tested are considered as promising potential radioprotectors that effect seems to be reasonable to study in vivo.

[Intercellular contacts accelerate the growth of cell colonies in a chick embryo cell culture]. / Mezhkletochnye kontakty uskoriaiut rost kletochnykh kolonii v kul'ture kletok kurinogo émbriona.

In sparsely seeded (1.10(3) cells/sm2) chick embryo cell cultures no cell proliferation commonly occurs. However, such factors as increasing cell density, a conditioned medium, or addition of ethanol fixed homologous cells to the culture may accelerate the cell growth. The mitogenic action of fixed cells serves as a contact stimulation of cell proliferation (Gasparian, Grigorian, 1989, 1990). Distant and contact cell-to cell interactions, that involve soluble and insoluble cell derived mitogens, are supposed to operate during the log phase of culture growth. The addition of an excess of cells to the previously sparse culture may mimic the cell microenvironment commonly existing in subconfluent cultures. The role of diverse cell-to cell contacts in the cell growth regulation is discussed. The addition of ethanol-fixed cells may improve the cell cloning technique.

[The kinetic characteristics of the process of the contact stimulation of cell multiplication in a chick embryo cell culture]. / Kineticheskie kharakteristiki protsessa kontaktnoi stimuliatsii kletochnogo razmnozheniia v kul'ture kletok kurinogo émbriona.

As was reported elsewhere (Gasparian, Grigorian, 1989a, 1989b), the stimulation of cell proliferation takes place in established culture of chick embryo cells after adding a suspension of living or inactivated homologous cells. In the present paper the kinetic parameters of this process, termed as the contact stimulation of cell proliferation, were studied. The dose- and time-dependence of cell response to the stimulus is described. It was shown that the addition of cells activates cell growth both in exponential and stationary cultures. DNA synthesis in resting cells is seen initiated only if their continuous interaction with the added cells is provided. The nature of signals involved in the process of contact stimulation is described.