[Growth peculiarities of commensal Escherichia coli isolates from the gut microflora in Crohn's disease patients].

Verhulst's logistic differential equation, popular in mathematical ecology, is used in modeling of population growth, neural networks, statistics, reaction models, Fermi distribution, modeling of tumor growth, etc. We used this function to characterize growth of commensal Escherichia coli isolates from gut microflora in Crohn's disease patients. The results of our investigations show differences in growth parameters of commensal E. coli, isolated from the gut microflora in Crohn's disease patients and healthy volunteers; it is most likely explained by the influence of chronic inflammatory processes on growth and reproduction of these bacteria. It has been established that the used mathematical model well characterizes growth of patients' gut E. coli isolates, and it can be important for the expedient probiotics' application during the disease.

[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.

Cell-cell contacts accelerate cell colony growth in sparse cultures of chick embryo fibroblasts.

There is no cell proliferation in very sparcely plated chick embryo cell cultures. Substituting conditioned medium or adding of ethanol-fixed homologous cells to the cultures accelerates cell colony growth. The mechanism for the mitogenic action of fixed cells is considered to be the contact stimulation of cell proliferation, and addition of extra cells to sparse culture is believed to mimic the cell micro-environment existing in subconfluent cultures. The role of diverse cell-cell contacts in cultured cell growth regulation is discussed. The procedure used (addition of ethanol-fixed cells) may improve normal cell cloning techniques.

[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.

[A possible pathway for mitogenic signal transmission during the contact stimulation of the multiplication of cultured cells]. / Vozmozhnyi put' peredachi mitogennogo signala v protsesse kontaktnoi stimuliatsii razmnozheniia kul'tiviruemykh kletok.

Cultured cells of the Japanese quail embryo were labeled with 3H-glucosamine, fixed, suspended and inoculated into built-up cultures of the homologous cells. The transfer of insoluble components of labeled cell surface into the cells of underlaying cell sheet was revealed. A decrease in the cell incubation temperature up to 4 degrees C blocks the process. The exchange of cell surface sites between contacting cells seems to be one of the possible ways of information transmission from one cell into another during contact regulation of cell proliferation.

[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.

Evidence for contact stimulation of growth of homologous cells in superinoculated cultures of chick embryo cells.

The secondary cultures of chick embryo cells were suspended and transferred to homologous cell cultures. Cell adhesion and proliferation were studied in these superinoculated cultures. It was shown that added cells soon adhered to the underlying cell layer which results in a prompt increase in culture density followed by the activation of DNA synthesis and cell division. Stimulation of cell proliferation involved both cell subpopulations composing the superinoculated culture: cells seeded on the built-up cell layer and cells of the layer. The contact nature of added cell mitogenic action on overlaid cell proliferation was evidenced. The cell system described can be used to investigate the adhesive properties of the cell layer apical surface, the relationship between cell growth rate and culture density, and the contact stimulation of cell proliferation.

Chronopharmacology of strophanthin and inderal: an experimental study.

Chronopharmacological investigations were performed in 54 guinea pigs and 126 white mice to explore their tolerance to arrhythmogenic and lethal doses of strophanthin, and changes in sensitivity to threshold antiarrhythmic dose of inderal during 24 hours. The investigations were carried out at a 4-hour interval, i.e., six times in 24 hours. The data obtained were processed using the approximation method to determine sinusoid fluctuations with an initially given period (cosinor analysis) and with an unknown period (non-linear least-square method in combination with the method of gradual approximation) on an EC 1045 computer and a DZ 28 microcomputer. It was found that strophanthin toxicity in guinea pigs and white mice reaches a maximum in the late evening, night and early morning hours. The acrophases of circadian rhythms of chronotolerance to the threshold arrhythmogenic dose of strophanthin, and those of chronosensibility to inderal are virtually identical.

[The characteristics of the stimulation of the proliferation of cultured chick embryo cells during reseeding]. / Osobennosti stimulirovaniia proliferatsii kul'tiviruemykh kletok kurinogo émbriona pri pereseve.

The growth rate of chick embryo cells in slowly proliferating cultures is activated after substitution of conditioned medium by fresh one with serum. After cell replanting, the stimulation of cell proliferation takes place in both media with the same effectiveness. In serum-less medium replanted cells do not adhere to glass and die. The results suggest that cells reversibly lose their dependence upon serum growth factors and population density, as a result of replanting, but retain anchorage-dependence for growth.

[Contact stimulation of the proliferation of cultured chick embryo cells]. / Kontaktnaia stimuliatsiia proliferatsii kul'tiviruemykh kletok kurinogo émbriona.

It was reported elsewhere (Gasparian, Grigorian, 1989a) that in the secondary chick embryo cell culture, after its superinoculation with additional homologous cells, the cell population density increased and the cell proliferation was activated. It has been shown in the present paper that the cell proliferation rate increase after inoculation of fixed cells, as well. The results obtained are discussed as a direct evidence for growth-stimulating effect of contacts between homologous cells.

[Stimulation of multiplication of chick embryo cultured cells after an increase in density of the cellular population]. / Stimuliatsiia razmnozheniia kultiviruemykh kletok kurinogo émbriona posle pobysheniia plotnosti kletochnoi populiatsii.

The secondary culture of chick embryo cells in 2-3 days after seeding was super-inoculated with homologous cells. Suspended cells adhere and spread on the cell layer whereby the culture density increases quickly. After adhesion of exogenous cells to the layer the stimulation of cell proliferation takes place. This activation is not connected with methodical manipulations or with the influence of conditioned medium factors. The results suggest that the increase in cell number itself does not arrest cell multiplication. It is proposed that the known phenomenon of blocking cell proliferation in dense cultures cannot be attributed only to effects of high cell density.

[Relation between extra- and intracardiac anti-strophanthin properties of anti-arrhythmic agents]. / Sootnoshenie ékstra- i intrakardial'nykh antistrofantinovykh svoistv antiaritmicheskikh veshchestv.

Animal experiments have shown that beta-adrenoblockers have the most marked antistrophanthin properties while antiarrhythmic agents with locally anesthetic attributes are less active. All the substances studied have proved to be ineffective on the cellular model of strophanthin arrhythmia. The data obtained suggest that the antiarrhythmic effect of the substances under study including beta-adrenoblockers is exercised on the level of the receptor apparatus of the postsynaptic membrane. The membrane stabilizing properties do not play the decisive role in ensuring the antiarrhythmic effect in strophanthin arrhythmia.

[Formation of the population composition of a stationary cell culture and the participation of nonproliferating cells with a doubled DNA content in regulating its density]. / Formirovanie populiatsionnogo sostava statsionarnoi kletochnoi kul'tury i uchastie neproliferiruiushchikh kletok s udvoennym soderzhaniem DNK v reguliatsii ee plotnosti.

The conditions of the cultivation of chick embryo diploid cells were alternated (prolonged maintenance with or without medium replacement, with or without consequent cell replating in fresh medium). In different times of culture growth, the cell DNA content was assessed by cytophotometry; the percentage of non-labeled mitoses after incubating the cells with 3H-thymidine and colcemide, as well as the cell density were determined. The phenomenon, detected earlier, of the accumulation of cells containing 4c DNA during the transition of the culture from logarithmic into the stationary phase of growth, was confirmed. These cells were shown to differ in their ability to survive in conditions of stationary culture and by proliferative potential. The fraction of cells reversibly arrested in G2-period was described, by which fraction the change of the cell population size is occurring after the decrease of its proliferation rate. The transitional stage is distinguished at the beginning of the stationary phase of culture growth. During this stage the stabilization of structural and numerical composition of the population is taking place.

[Accumulation of nonproliferating cells containing 4c DNA in stationary diploid cell cultures]. / Nakoplenie neproliferiruiushchikh kletok, soderzhashchikh 4c DNK, v statsionarnykh kul'turakh diploidnykh kletok.

The cell proliferation was stimulated in stationary cultures of chick and human embryo cells by changing the medium. The cumulative indices of labeled cells and labeled mitosis as well as the cellular DNA contents were determined in the stimulated cultures at different times of growth until their entry into the stationary phase of growth. It is established that in the case of mass entry of cells into DNA synthesis period, part of them does not complete the mitotic cycle to be arrested in the G2-period. This arrest is considered as one of the ways of the cell proliferation inhibition in cultures entering into the stationary phase.

[Studies of nucleic acid metabolism in cultured chick embryo cells infected with Mycoplasma gallisepticum]. / Izuchenie metabolizma nukleinovykh kislot kul'tiviruemykh kletok kurinogo émbriona, zarazhennykh Mycoplasma gallisepticum.

M. gallisepticum infection of cultured chick embryo cells led to a sharp reduction the rate of 3H-thymidine and 3H-uridine incorporation into DNA and RNA cells, and almost completely suppressed the transposition of uridine label from the nucleus into the cytoplasm, this pointing to the inhibition of escape of RNA synthesized de novo into the infected cells cytoplasm. As suggested, weak labeling of the cytoplasm after prolonged (about several hours) incubation of cultured cells with labeled urine could indicate infection of cell cultures with the mycoplasmae.

[Protein SH-group concentration and RNA synthesis during the process of induction of proliferation in the stationary phase of cell culture growth]. / Kontsentratsiia belkovykh SH-grupp i sintez RNK v protsesse induktsii proliferatsii v statsionarnoi rosta kul'tur kletok

The dynamics of intracellular protein SH-group (PSH) content was studied cytochemically in the course of stimulation of cell proliferation in stationary cultures of an established Chinese hamster cell line and of human diploid embryo fibroblasts. The results were compared with the pattern of RNA synthesis during the prereplicative period. In Chinese hamster cells immediately after medium changing in stationary cultures there is an augmentation of PSH content in parallel withe the increase in RNA synthesis rate. Later on, the rate of RNA synthesis and PSH content are seen decreasing followed by a new increase in the rate of RNA synthesis correlated with the second rise in PSH content. In stationary cultures of human diploid fibroblasts, there is also an increase in the rate of RNA synthesis and in the content of SH after medium changing, but the second wave of RNA synthesis and the second rise in PSH content are not pronounced. The variation in PSH content reflects the shift in the cell metabolism during the prereplicative period and is not attributed to changes in cell protein content.