[Toxicity of magnetite-dextran particles: morphological study]. / K voprosu o toksichnosti magnetit-dekstranovykh chastits: morfologicheskioe issledovanie.

Females of OFI mice were given single repeated intravenous injections of magnetite-dextran nanoparticles (MD3), the total partical diameter being 49 nm, with the magnetic core diameter equal to 10-15 nm. MD3 is a superparamagnetic preparation commonly used for magnetic resonance imaging (MRI). The liver, spleen, heart, kidney, and lung microstructures of these mice were determined after MD3 administration. Both dose- and time-dependent changes in the examined organs were compared after single and repeated MD3 doses. MD3 induces an increse in ferritine and iron levels in all the organs, the appearance of small aggregates of lymphoid cells in the liver, the appearance of iron-containing cell formations in hepatic sinusoids, presumably composed of the Kupffer cells and portal macrophages, splenomegaly, and hemostasis of spleen blood vessels. The pronounced morphological alterations have been revealed primarily in the liver and spleen after a single administration of high MD3 doses and after repeated MD3 injections. The results of The present investigation seem to narrow somewhat the safety limits of superparamagnetic iron oxide particles. Nevertheless, the degree of morphological changes in the liver and spleen in our experiments appeared to be rather low even after a single MD3 dose that exceeds approximately by 200 times a dose necessary for diagnostics in MRI.

[The possibility of performing artificial selection in vivo for a change in the mutability level in populations of mouse bone marrow stem cells]. / O vozmozhnosti provedeniia iskusstvennogo otbora in vivo na izmenenie urovnia mutabil'nosti v populiatsiiakh stvolovykh kostnomozgovykh kletok myshei.

Bone marrow cells of CBA males were transplanted to irradiated syngeneic females and after 13 days the mean frequency of blood erythrocytes with micronuclei, cloning efficiency of haemopoietic stem cells (HSC), and variability range of frequency of cells with micronuclei in spleen colonies were studied in 44 primary recipients. A wide range of variability has been shown for the indicators of mutability and cloning efficiency (0.1-1.8% for frequency of erythrocytes with micronuclei, 200-300-1500 for cloning efficiency, 0.1-0.5% for frequency of cells with micronuclei in spleen colonies of individual transplants). A weak negative correlation between the frequency of erythrocytes with micronuclei and the cloning efficiency was observed. We conclude that the difference in frequency of erythrocytes with micronuclei between HSC subpopulations is sufficiently high to carry out an artificial selection for high and low mutability in the course of transplantations. The cloning efficiency can be increased when spleen colonies are studied by micronuclear analysis. Data on the importance of such a selection in studying the behavior of "mutability" and "cloning efficiency" characters, immortalization, "aging", and death of HSC populations of CBA mice have been reported.

[The heterogeneity of cell populations by the cytochemical characteristics of the cellular chromatin]. / Geterogennost' kletochnykh populiatsii po tsitokhimicheskim kharakteristikam khromatina kletok.

Cell heterogeneity of cytochemical characteristics of chromatin in the norm and after provocative factors in vitro (a heating at 45 degrees C, X-irradiation and joint actions of heating and X-ray irradiation) was investigated in the peripheral blood mononuclear cells of sheep and mouse, the lymphoid cell populations of the murine bone marrow, spleen and thymus. As a criterion of cytochemical heterogeneity were used the distinctions in the rate of staining of cell nuclei with DNA-specific dyes, that was registered by means of measurement of coefficient variation of the DNA-histogram basis peak, with a flow cytometry. Heterogeneity of cytochemical characteristics are dealt with showed a variability of spatial organization of interphase nuclei of single cells. The provocative factors bring about a decrease in the level of the cytochemical characteristics heterogeneity in the sheep mononuclear cells. In the murine cell populations studied no such equalizing of the marker of variability was revealed.

[The dynamic proliferative activity of mouse bone marrow cells during the suppression and recovery of hemopoiesis after 5-fluorouracil administration to the animals]. / Dinamika proliferativnoi aktivnosti kletok kostnogo mozga myshei v period supressii i vosstanovleniia gemopoéza posle vvedeniia zhivotnym 5-ftoruratsila.

Males of CBA x C57BL/F1 mice were given a single intravenous injection of 5-fluorouracil (5-FU; 0.15 mg/g of body weight), and their hematopoietic cell status was determined on days 2, 4, 7, 15 after 5-FU administration. Femoral cellularity and cycling cells were assessed in unfractionated bone marrow and cellular fractions separated by Percoll density gradient (fraction 2: 1.056 < P < 1.067 g/ml and fraction 3; 1.067 < P < 1.076 g/ml). To evaluate the functional status of cells that survived after the 5-FU administration, mice were given a second dose of 5-FU, 4 or 14 days after the first administration, or were subjected to X-irradiation (3.2 Gy), thermal burn (3-B rate on the crupper 1.2 x 1.2 mm) and X-irradiation plus the burn one day before sampling. It is shown that during a nadir period of hematopoiesis (4 days after 5-FU insult) the share of entry into the cycle is reduced in proliferating cells from a unfractionated bone marrow, from fraction 3, and the cycling fraction 2 up to 2.6, 4.0 and 17.4 per cent, compared to the norm (the pretreatment level). The cell populations selected by 5-FU become most sensitive to additional injuries (drug and physical stress-factors) 4 days after the first dose of 5-FU, but become resistant again to a second dose of 5-FU and the physical stress-factors 14 days after the first administration. The irradiation of mice as well as the thermal burn after 5-FU injection aggravate the effect of the latter, and X-irradiation+burn, on the contrary, reduce the severity of 5-FU after-effect.

[The effect of cadmium on the survivability of colony-forming hematopoietic cells in mice exposed to x-ray irradiation]. / Vliianie kadmiia na vyzhivaemost' kolonieobrazushchikh krovetvornykh kletok u myshei pri rentgenovskom obluchenii.

It has been reported elsewhere that in addition to enhancing the expression of metallothionein genes, the previous injection of cadmium salts into sublethally X-irradiated mice increases by 10 times the number of endogenous spleen colonies. To understand the mechanism of the strong radioprotective cadmium effect donors and recipients were treated separately. It is shown that the survival of exogenous bone marrow colony-forming cells in lethally irradiated recipient remains at the control level independently of the donor cadmium treatment, whereas the injection of cadmium nitrate to recipient mice leads to the stimulation of colony formation by 1.7-1.8 times. The data allow to conclude that the cadmium effect on the survival of colony-forming hemopoietic murine cells after X-irradiation is not mediated by the enhanced expression of metallothionein genes.

[The effect of recombinant human interleukin-1 beta on the repopulation of bone-marrow colony-forming cells in mice subjected to the action of radiation and burns]. / Vliianie rekombinantnogo interlekina-1 beta cheloveka na repopuliatsiiu kostnomozgovykh kolonieobrazuiushchikh kletok u myshei, podvergnutykh deistviiu radiatsii i ozhoga.

The radioprotective and restorative (therapeutic) effects of human recombinant interleukin-1 beta (IL-1 beta) on the population of bone marrow CFU-S of mice, subjected to either sublethal doses of ionising irradiation itself or the same irradiation in combination with thermal burn, are investigated. Both the effects of the agent are registered under both in vitro and in vivo irradiation in semi-, syn- and allogeneic animals. If the irradiation was combined with thermal burn, the "therapeutic" effect of the agent was demonstrated at irradiation dose equal to 3.06 Gy rather than to 6.12 Gy. If the bone marrow cells were irradiated in vitro in dose 3.06 Gy with the following heat shock at 42 degrees C for 10-20 min, the "therapeutic" effect of IL-1 beta was seen only if it was added to cells before rather than after irradiation. The radioprotective effect of IL-1 beta is maintained under in vitro, as well as in vivo conditions in the allogeneic system of transplantation of the CBA donor bone marrow to the C57BL mice.

[Epidermal growth factor with insulin used for stimulation of exogenous colony formation in the spleen of mice irradiated with lethal doses of X-rays]. / Stimuliatsiia épidermal'nym faktorom rosta sovmestno s insulinom obrazovaniia ékzogennykh kolonii v selezenke myshei, letal'no obluchennykh rentgenovskimi luchami.

Epidermal growth factor (12 ng per 1 g of body mass) and insulin (0.004 units per 1 g of body mass) were introduced into X-ray irradiated (1.8, 2.12, 2.7 Cr) mice. Four hours later bone marrow was extracted from femurs to be introduced into syngenic lethally irradiated recipients. On the 11th day after transplantation the number of exogenic spleen colonies was computed. The epidermal growth factor, in combination with insulin, stimulates in the organism the restoration of hemopoietic colony-forming cells after radiation injury.

[Redistribution of bone marrow cells according to mitotic cycle phases after the action of agents altering the intracellular concentration of cyclic nucleotides]. / Pereraspredelenie kostnomozgovykh kletok po fazam mitoticheskogo tsikla posle deistviia agentov, izmeniaiushchikh vnutrikletochnuiu kontsentratsiiu tsiklicheskikh nukleotidov.

The method of flow cytofluorometry was used to determine the distribution of murine bone marrow cells along the phases of the cell cycle in normal mice (CBA X C57Bl) F1 after the whole body equal X-ray irradiation, after irradiation in combination with burn, after administration of imidazole, insulin and caffeine, and after the treatment of cells by acetylcholine. In non-irradiated mice insulin and caffeine induced an increased ratio of bone marrow cells in G0 and G1 and a reduced one in S phase. Imidazole increased the number of G2- and M-cells by 1.5 times only in regenerating bone marrow of irradiated mice. After X-ray irradiation of mice at a dose of 2.3 Gy, reducing the percentage of cells in S and increasing it in G2 and M phases, insulin, acetylcholine and caffeine were found to decrease the number of cells in G2 and M phases: besides, caffeine and acetylcholine increased the percentage of S-phase cells. The data obtained are discussed in terms of possibility of normalization of bone marrow cell proliferation broken after exposure to physical stress-factors.

[Insertion of the bacterial gene for dihydrofolate reductase into colony-forming cells of mouse bone marrow]. / Vvedenie bakterial'nogo gena digidrofolatreduktazy v kolonieobrazuiushchie kletki kostnogo mozga myshi.

Introduction of the plasmid containing the methotrexate-resistant (Mtx-r) bacterial gene of dihydrofolate reductase (DHFR) under the control of the early promoter of SV 40 into the donor bone cells of the mouse with subsequent transplantation of the cells into lethally irradiated mice results in the increase in the life span of mice under conditions of methotrexate selection. It is due to the stable transformation of the bone marrow colony-forming cells with the plasmic DNA and the synthesis of the bacterial Mtx-r DHFR in the spleen and bone marrow of the recipient mouse.

[Flow fluorimetry of the cellular DNA of the bone marrow in normal mice and after exposure to extreme factors]. / Protochnaia fluorimetriia DNK kletok kostnogo mozga myshei v norme i posle vozdeistviia ékstremal'nykh faktorov.

The distribution of murine bone marrow cells in regard to cell cycle was examined using flow cytometry technique. In normal NIH mice the percentage of cells being into phases G1/0, S and G2 + M constitutes 78, 15 and 7%, respectively. In mice subjected to X-irradiation (2, 12 Gy), the thermal burn, and X-irradiation plus the burn the proportion of G2 + M-cells increased, which may be presumably due to their delay on stage G2 of the cell cycle. The start and duration of the delay in the G2 phase depend upon the kind of damage applied.

[Genome mutation frequency in the cells of spleen colonies of different origins in NIH mice]. / Chastota genomnykh mutatsii v kletkakh selezenochnykh kolonii razlichnogo proiskhozhdeniia u myshei NIH.

Genome mutation frequencies (GMF) were determined in cells of endogenous (from bone marrow) and exogenous (from bone marrow, spleen and embryonic liver) spleen colonies on the basis of variations in DNA contents of interphase nuclei. In cells of the former GMF varied from 1.1 X 10(-2) to 10.8 X 10(-2), and in the latter these were equal to 8.9 X 10(-2). In the cells of exogenous colonies derived from X-irradiated precursors (1.8 and 5.9 Gy) GMF were 10.1 X 10(-2) and 11.9 X 10(-2), resp. The mode of transplantation influenced greatly on the GMF: after an additional short transplantation (4-6 days) the number of GMF increased by 1.5-2 times. It is concluded that the increased number of GMF may be responsible for the limited life-span of bone marrow stem cells in the course of their serial transplantations in the irradiated syngenic mice.

[Acid hydrolysis characteristics of spleen colony cells under Feulgen staining]. / Kharakteristiki kislotnogo gidroliza pri okraske po Fël'genu kletok selezenochnykh kolonii.

A cytophotometrical determination of DNA content was performed in cells of murine spleen colonies originating from bone marrow and in lymphocytes of axillary lymph nodes under various temperatures (22, 25 and 37 degrees C) of hydrolysis (5N HCl). It is shown that acid hydrolysis at 20 and 25 degrees C is most-preferable for proliferated cells of spleen clones and for non-proliferated lymphocytes. It is concluded that hydrolysis curves for clonal cell nuclei in different phases of mitotic cycle practically coincided.

[3',5'-AMP content of the bone marrow in mice during radiation and thermal injury]. / Soderzhanie 3',5'-AMP v kostnom mozge myshei pri radiatsionno-termicheskoi travme.

An elevated level of cAMP as compared to the control was observed in the bone marrow of mice 2 and 20 h after radiation-thermal trauma. No potentiation of burn and radiation effects was noted. It is assumed that thermal factor causes a delay of proliferating cells at the cycle stage where the level of this nucleotide achieves its maximum value without any influence.

[Frequency of genome mutations in progeny of colony-forming bone marrow cells in BALB/c mice]. / Chastota genomnykh mutatsii v potomstvakh kolonieobrazuiushchikh kletok kostnogo mozga myshei BALB/c.

Spleen colonies of syngenic bone marrow cells were grown in sublethally irradiated BALB/c mice. DNA contents of interphase nuclei of the colony cells have been measured using the Feulgen cytophotometry. The rates of appearance of cells with variations in chromosome number were calculated according to the following equation: (Formula: see text), where No - the total number of colonies, Nm - the number of mutant colonies, and n- the number of cells examined. The rate of genome mutations was found to be 7.7 +/- 0.6X X10(-2) per cell per generation. Binominal distribution of clones according to the number of mutant cells has been noticed. Cells with decreased numbers of chromosomes (hypodiploid mutants) were of a more frequent occurrence than cells with increased chromosome numbers (hyperdiploid mutants). It is concluded that the propagation of colony-forming bone marrow cells in irradiated animals is accompanied by almost the same increase in frequency of genome mutations as in the case of the cultivation of cells in monolayer cultures.

[The hematopoietic colony-forming cell--object of experimental study]. / Krovetvornaia kolonieobrazuiushchaia kletka--ob'ekt éksperimental'nogo issledovaniia

Studies dealing with the colony-forming cell as a subject of experimental research are reviewed. The techniques of cultivation of colony-forming cells, their proliferation, differentiation and self-renewal have been considered.