[The assessment of biocenosis contamination in the region of radioactive waste storage (RWS) placing and influence of this storage on rodents].

The results of radiative and of chemical monitoring show definite contamination of this zone by 90Sr and toxic metals. The essential local contaminations of geosystems (up to 2.3 x 10(4) Bk/kg of soil) require in environmental condition assessment at biocenosis level. Biotesting found the increase of metallothioneines levels in kidney (up to 15.63 microg/g of tissue) and liver (up to 19.22 microg/g of tissue) of rodents inhabited in the region of RWS placing as compared with the control group (3.51 and 4.44 microg/g of tissue accordingly). Besides, the decrease of total quantity of leucocytes (by 14.5% as compared with the control group) and absolute quantity all forms of them in animal blood were noted. It was assumed the increase of protein--MT is the result of complex influence by ionizing radiation and toxic metals.

[Immunotoxicity of aluminum chloride]. / Immunotoksichnost' khloristogo aliuminiia.

Aluminum chloride was tested for its effect on primary T-dependent humoral immune response. The administration of aluminum chloride in the genotoxic dose (0.04 M) caused in mice a profound immunosuppressive effect accompanied by diminished thymic and splenic cellularity. The findings suggest that aluminum chloride possesses marked immunotoxic properties.

[Metallothionein content in tissue and neoplasms of mice under cadmium chloride administration and gamma irradiation. Increased radioresistance in mice with elevated level of metallothionein]. / Soderzhanie metallotioneinov v tkaniakh i opukholiakh myshei pri kombinirovannom deistvii kadmiia i gamma-izluchenia. Uvelichenie radiorezistentnosti myshei s povyshennym urovnem metallotioneinov.

It was confirmed that the survival of gamma-exposed mice became higher after preliminarily subcutaneous injections of cadmium chloride. It is supposed that radioresistance of mice is connected with the induction of metallothionein proteins by cadmium chloride.

[The reference information system "Ecology and aluminum toxicology"]. / Informatsionno-spravochnaia sistema "Ekologiia i toksikologiia aliuminiia".

Views of the toxicity of aluminum to man, animals, and plants and on its behavior in the ecosystems with a changing man-made loading have changed in the past 30 years. Aluminum along with its human medical consequences has been found to present problems on the acid soils in world agriculture. To systematize knowledge and to control information on aluminum and its compounds, the reference information system "Ecology and Aluminum Toxicology" whose structure is based on the developed model of an ecological aluminum cycle was designed. Basic information units were identified in a rather wide subject area: "Generation", "Spread", and "Action", which include the information available in the published materials and the data obtained in the authors' experimental studies.

[Aluminum induces chromosome aberrations in wheat root meristem cells]. / Aliuminiiindutsiruet aberratsii khromosom v kletakh kornevoi meristemy pshenitsy.

The yield and pattern of chromosome structure aberrations in wheat seedlings treated with aluminum nitrate and aluminum sulfate at various concentrations have been determined by the anaphase method. Aluminum has a genotoxic effect causing genome, chromatid, and chromosome aberrations in apical root meristem cells. The relationship between the total yield of structural mutations and the aluminum concentration follows a bell-shaped curve. The mutagenic activity of aluminum nitrate peaks at 10(-3) mg/ml, which is twice as high as the permissible concentration limit (PCL) of aluminum in potable water. The maximum of the mutagenic activity of aluminum sulfate is observed at 5 x 10(-4) mg/ml, i.e., one PCL. Tap water boiled for 2 h in an aluminum vessel has virtually no genotoxic effect on wheat cells.

[The combined action of gamma irradiation and hyperthermia on the structure of the cell population in the Chinese hamster]. / Kombinirovannoe deistvie gamma-oblucheniia i gipertermii na strukturu populiatsii kletok kitaiskogo khomiachka.

A change in the structure of FAF-28 Chinese hamster cell population occurred during 24 h following gamma-irradiation or hyperthermia heating, or the effect of both factors was studied by flow cytofluorometry. With radiation delivered immediately after heating the distribution of cells among cycle phases was nearly the same as with hyperthermia alone: the share of cells at the S-phase was invariable during the first 4-6 h, then it slowly diminished; at G1 it slowly decreased and at G2 increased. When irradiation preceded heating the pattern of cell redistribution during the first hours was the same as that with radiation alone: the "wave" of transition from G1 to S phase was the same, but shorter in amplitude and longer in time; then cells were accumulated at G2+M and remained there for 24 h. Thus, of the two factors applied, the first was the major one in changing the cell population structure during the first hours after treatment. In 24 h the result was the same, that is, the considerable accumulation of cells at G2+M.

[DNA replication in mammalian cells after the action of physical, chemical or biological factors. VI. The recovery of DNA synthesis in a culture of irradiated cells]. / Replikatsiia DNK v kletkakh mlekopitaiushchikh posle deistviia faktorov fizicheskoi, khimicheskoi ili biologicheskoi prirody. VI. Vosstanovlenie sinteza DNK v kul'ture obluchennykh kletok.

The kinetics of DNA synthesis restoration in cultured HeLa cells and in L-929 mouse fibroblasts irradiated by gamma-rays of 60Co with a dose of 10 Gy was studied. Early after irradiation the rate of DNA synthesis in HeLa cells measured with 3H-thymidine incorporation was seen to decrease. Two hours later the incorporation starts to increase to reach the control level 4 hours after irradiation and then becomes even higher than this level. The distribution of cells among phases of the cell cycle measured with flow cytometry undergoes changes. 4-6 hours after irradiation part of S-phase cells increased contributing presumably to the elevating of 3H-thymidine incorporation observed at this time. The restoration of the incorporation was suppressed by inhibitors of protein and RNA synthesis--cycloheximide and actinomycin D. It is suggested that the processes of restoration of DNA synthesis in irradiated cells can be of inducible nature. In irradiated HeLa and L-929 cells the restoration of DNA synthesis is resistant to novobiocin, an inhibitor of DNA replication.

Inducible processes in DNA replication and repair after gamma, UV-irradiation and action of some chemicals in mammalian cells.

Restored DNA synthesis in mammalian gamma-, UV-irradiation and action of FdUrd was shown to be resistant to gamma- and UV-irradiation or heating. This correlates well with changes in chromatin structure and perhaps depends on the modification of the latter. For studying possible inducible characteristics of restored process of DNA synthesis the irradiated cells were incubated with cycloheximide (1 or 10 micrograms ml-1) or actinomycin D (0.05 ug ml-1). It was shown that in the presence of cycloheximide or actinomycin D restoration of DNA synthesis did not occur. A high rate of postreplicative DNA repair in UV-irradiated HeLa cells occurs after the previous action of FdUrd or UV-irradiation. Under these conditions daughter DNA strands have few gaps. Two-dimensional gel electrophoresis of proteins from the cells with resistant DNA synthesis demonstrates higher level some of these and lower one of the other proteins.

[Mathematical modeling of the processes of DNA synthesis in irradiated cells and cell populations. Modeling of the initiation and elongation of DNA chains in irradiated mammalian cells]. / Matematicheskoe modelirovanie protsessov sinteza DNK v obluchennykh kletkakh i kletochnykh populiatsiiakh. Modelirovanie initsiatsii i élongatsii tsepei DNK v obluchennykh kletkakh mlekopitaiushchikh.

Dose-dependence of DNA synthesis inhibition in cells of HeLa suspension culture, bone marrow and thymus of mice was investigated. A contribution of inhibition of replicon synthesis and DNA chain elongation to the total effect of DNA synthesis inhibition by gamma-radiation was estimated by mathematical simulation. The method is proposed for evaluation of Di that characterizes cell radiosensitivity. Radiosensitivity of HeLa cells after preirradiation or exposure to 5-fluorodeoxyuridine was assessed.

[Gamma-irradiation induces in HeLa cells radioresistant DNA synthesis]. / Gamma-obluchenie indutsiruet v kletkakh HeLa radiorezistentnyi sintez DNK.

Cells of a suspension HeLa culture at the logarithmic phase of growth were exposed to 60Co-gamma-rays (5 Gy), incubated in the nutritious medium, and in 4 h subjected to repeated irradiation: the dose-response function and the dynamics of DNA synthesis inhibition were determined. It was shown that DNA synthesis was inhibited to a lesser extent after preirradiation, in other words, DNA synthesis was radioresistant. A correlation between this synthesis and reproductive cell death is discussed.

[Suppression of the initiation of DNA synthesis as an index of cellular radiosensitivity]. / Podavlenie initsiatsii sinteza DNK kak pokazatel' radiochuvstvitel'nosti kletok.

A gamma-radiation dose (Di) suppressing DNA synthesis initiation by 35% in primary suspension cultures of mammalian cells, is nearly the same as D0 for survival of clonogenic cells of the same lines and tissues. The extent of DNA synthesis suppression is assessed by impulse 3H-thymidine incorporation in the acid-insoluble fraction of irradiated cells. The values of Di determined in this way for HeLa cells, Ehrlich ascites tumor cells, mouse bone marrow and thymus cells are 2.0, 1.5, 1.5, and 1.0 Gy, respectively; as determined by clonogenic capacity of these cells, Di = 1.9, 2.0, 1.3, and 1.0 Gy, respectively.

Effect of fluorodeoxyuridine on the sedimentation of nucleoids from HeLa cells in sucrose gradients.

Sedimentation properties of nucleoids from HeLa cells cultured for 6 or 24 h with 10(-6) M fluorodeoxyuridine (FdUrd) were studied in neutral sucrose gradients. Independently on the presence and concentrations of ethidium bromide in the gradient, nucleoids from FdUrd treated cells sedimented farther than those from untreated cells. However, the maximum relaxation of supercoiled DNA, observed at the concentration of 5 micrograms/ml of ethidium bromide, was significantly lower in cells treated with FdUrd, which indicated that prior incubation with FdUrd did not increase the degree of DNA supercoiling but altered by some way the conformation of DNA in nucleus. Previously we have found, that treatment of HeLa cells with FdUrd resulted in the stimulation of DNA synthesis, which proved to be resistant to ultraviolet and gamma-irradiation. From the present results it is possible to suggest, that alterations of chromatine structure should be included in facilitating of DNA synthesis on DNA template damaged by ultraviolet or gamma irradiation.

[DNA replication in mammalian cells after the action of factors of a physical, chemical or biological nature. V. The structural reorganization of replicating DNA in HeLa cells after incubation with 5-fluorodeoxyuridine]. / Replikatsiia DNK v kletkakh mlekopitaiushchikh posle deistviia faktorov fizicheskoi, khimicheskoi ili biologicheskoi prirody. V. Reorganizatsiia struktury replitsiriushchei DNK v kletkakh HeLa posle inkubatsii s 5-ftordezoksiuridinom.

A study was made of sedimentation properties of the nucleoid (chromatin) of HeLa cells with radio- and thermostable mode of DNA synthesis induced by 5-fluorodeoxyuridine (FUdR). After the incubation of HeLa cells with FUdR (10(-6) M, 6 h or 24 h) the rate of nucleoid sedimentation was shown to rise by 40 and 25%, respectively. Maximum relaxation of the nucleoid was observed under 5 mg/ml ethidium bromide concentration in sucrose gradients. After the incubation with FUdR the nucleoid relaxes to a lesser extent, and after irradiation its response to ethidium bromide in various concentrations was similar to that of intact nucleoid, and by this property the "FUdR nucleoid" differs essentially from the irradiated "normal nucleoid". A model of chromatin structure of cells exposed to FUdR is proposed, based on the transformation of large domains in small ones, for the explanation of radioresistant DNA synthesis.

[Determination of the DNA-synthesizing cell count by the immunofluorescence method]. / Opredelenie kolichestva kletok, sinteziruiushchikh DNK, s pomoshch'iu immmunofluorestsentnogo metoda.

In DNA-synthesizing cells DNA is partially single-stranded. Anti-thymidine antibodies, while specifically reacting with this DNA, form a complex which may be revealed using indirect immunofluorescent technique. A comparative determination of DNA-synthesizing cell number in tumor tissue (larynx squamous cell carcinoma) was performed using immunofluorescent technique and radioautography. The former method showed the labeling index (LI) to vary from 1.2 to 9.9%, while the latter showed it to vary from 1.0 to 8.2%. The correlation ratio between the LI values obtained by the two techniques was 0.79. To eliminate a possible reaction of anti-thymidine antibodies with cellular RNA, specimens were preincubated in solutions with RNAase. No more than 6 hours were required to stain specimens using this LI estimation technique. This investigation allows to reveal DNA synthesizing cells not only in the periphery of a histological section, as does routinely radioautography, but also in its centre.

[Possible inducible nature of radioresistant DNA synthesis stimulated by 5-fluorodeoxyuridine]. / O vozmozhnoi indutsibel'noi prirode radiorezistentnogo sinteza DNK, stimulirovannogo v kletkakh deistviem 5-ftordezoksiuridina.

A study was made of the effect of cycloheximide on the radioresistant DNA synthesis stimulated by preincubation of cells with 5-fluorodeoxyuridine (FdUrd). It was shown that after the cycloheximide treatment the radioresistant DNA synthesis was absent while in FdUrd-treated cells it did occur. It is assumed that the FdUrd-stimulated radioresistant DNA synthesis is of an inducible nature.

[Thermal sensitivity of Ehrlich ascites cancer cells forming colonies in agar cultures in diffusion chambers]. / Termochuvstvitel'nost' kletok astsitnogo raka Erlikha, formiruiushchikh kolonii v agarovykh kul'turakh v diffuzionnykh kamerakh.

Thermosensitivity of clonogenic ascites Ehrlich carcinoma cells (AEC), forming colonies in agar cultures in diffusion chambers was studied when heating them in vitro at 41-44 degrees C. The clonogenic cells of AEC are shown not to essentially differ both in the colony-forming efficiency (CFE) and in the proliferative status on the 3rd and 7th days. No essential differences are revealed in thermosensitivity of such cells. The heating time-survival curves are exponential or S-shaped with a small "shoulder". The temperature increase by 1 degree C resulted in a 2-2.5-fold decrease in the time of effective hyperthermia treatment. The values of D0 for cells treated with 42 degrees C in different experiments varied from 20.1 min to 24.6 min. Only one type of thermal damage reaction with the energy of inactivation about 150 kcal/M was observed in AEC cells in the temperature range studied.

[5-fluorodeoxyuridine induces radioresistant synthesis of DNA and sensitizes HeLa cells to gamma radiation]. / 5-ftordezoksiuridin indutsiruet radiorezistentnyi sintez DNK i sensibiliziruet kletki HeLa k gamma-oblucheniiu.

It was shown that preincubation of HeLa cells with 5-fluorodeoxyuridine (10(-6) M) induced DNA synthesis resistant to gamma-radiation (6 Gy). At the same time, the death rate of exposed cells increased and nucleoid relaxation decreased. The role of DNA synthesis inhibitors in the reproductive death of exposed cells is discussed.

[DNA replication in mammalian cells exposed to the action of physical, chemical or biological factors. IV. 5-fluorodeoxyuridine modifies the effect of hyperthermia on DNA synthesis and the survival of HeLa cells]. / Replikatsiia DNK v kletkakh mlekopitaiushchikh pri deistvii faktorov fizicheskoi, khimicheskoi ili biologicheskoi prirody. IV. 5-ftordezoksiuridin modifitsiruet vliianie gipertermii na sintez DNK i vyzhivaemost' kletok HeLa.

Preliminary incubation of logarithmically growing HeLa cells with FUdR decreases an inhibitory effect of hyperthermia (43 degrees C, 1 hour) on DNA synthesis. The hyperthermia alone inhibits DNA synthesis considerably: the label in acid-precipitable material accounts for 30% of control level. Preliminary incubation of the cells with FUdR (10(-6)) for 24 or 6 hours (plus 18 hours in fresh medium) decreases the effect: the label yields account for 50 or 90% of the respective control levels. A molecular weight of nascent DNA synthetized in the cells after hyperthermia or incubation with FUdR is lower than the control one but it increases rapidly during postincubation. Nucleoid of cells treated with FUdR has a sedimentation velocity which exceeds that of the control cells by more than 25%. Preliminary incubation with FUdR sensitizes the cells to hyperthermia. The effect is not believed to be associated with cells synchronization since the treatment of the cells with FUdR for 2 or 6 hours, when FUdR itself does not exert its toxic effect, brings about sensibilization of cells to hyperthermia. It is suggested that modification of the cell viability and DNA replication are related to some changes of chromatine structure induced by FUdR.

[Sensitivity of DNA synthesis to gamma-irradiation in Ehrlich ascites carcinoma cells in stationary and logarithmic growth phases]. / Chuvstvitel'nost' sinteza DNK k gamma-oblucheniiu v kletkakh astsitnoi kartsinomy Erlikha v statsionarnoi i logarifmicheskoi stadiiakh rosta.

A study was made of the influence of gamma-radiation on DNA synthesis in cells of 3-day and 7-day Ehrlich ascites tumor cultures. DNA synthesis in cells of the 3-day culture was more sensitive to moderate radiation doses than those of the 7-day culture as was observed during the first 30 min after irradiation. After 3-hour postirradiation incubation, no appreciable difference was noted in radiosensitivity of DNA synthesis in the cells of the 3-day and 7-day cultures.