Biomedical subjects

Iu M Rozanov

Publications and source records attributed to Iu M Rozanov.

At least 19 recordsLinked to original sources

PubMed2006

[Variation of microsatellites BM224 and Bcal7 in populations of green toads (Bufo viridis complex) with various nuclear DNA content and ploidy].

We studied variation of microsatellites BM224 and Bcal7 in three species of the Bufo viridis diploid-polyploid complex. We found that locus Bcal7 in all examined samples was monomorphic. Three alleles of microsatellite BM224 were found. Among tetraploid toads, the western species B. oblongus had only one allele variant, whereas the eastern species B. pewzowi had two other alleles. Similar distribution of alleles was observed in triploid specimens, collected in the area borders of tetraploid and diploid species. Among samples of diploid toad B. viridis, we found all three allele variants of microsatellite BM224. Their distribution was geographically determined. A comparison of allele distribution with genome size variation in diploid toads showed very similar patterns.

Africa, Northern↗

PubMed2005

[Variability in size of the nuclear genome in pygmy wood mouse Sylvaemus uralensis (Rodentia, Muridae)].

Earlier, in an integral genetic study, the Asian and European races were distinguished within the species Sylvaemus uralensis (pygmy wood mouse) and the European race was divided into the East European and South European forms. Each of these groups differed from the others, in particular, in the quantity of the centromeric heterochromatin in karyotypes of the animals. To establish the pattern of its changes in S. uralensis, in the present study the DNA content in splenocyte nuclei in all races and forms of pygmy wood mice was assessed using DNA flow cytometry. The heterochromatin amount in karyotypes and genome size were shown to be correlated. The East European chromosomal race of S. uralensis (Central Chernozem and Non-Chernozem regions of Russia, Crimea Peninsula, Middle Volga region, and Southern Ural) and the Asian race of this species (East Kazakhstan, Uzbekistan, and East Turkmenistan), which have respectively the highest and the lowest amounts of centromeric heterochromatin in the karyotype, exhibit the greatest difference in the DNA content in the genome. On average, the difference is approximately 8% in males and 6.7% in females; in both cases, the ranges of variability were distinctly different. Against the general background of the trait variation, the Asian race, whose members have the smallest DNA amount in their cells, looks homogeneous. The genome of the South European chromosomal form of S. uralensis (Caucasus, Transcaucasia, Carpathians, and Balkan Peninsula), which exhibits an intermediate content of the centromeric heterochromatin in the karyotype, is smaller that the genome of the East European race (by 3.2% in the group of males and by 1.9%, in the group of females), but larger than that of the Asian race (by 5% in either sex). Thus, the variability of size of centromeric C-blocks in pygmy wood mouse is likely to be associated with elimination (or, conversely, an increase in the amount) of the genetically inert chromatin. It is suggested that a significant contribution to the variability of genome size in S. uralensis is made by heterochromosomes, or, more precisely, their variable regions, which seem to be largely heterochromatic.

Animals↗

PubMed2004

[High resolution analysis of replication foci by conventional fluorescent microscopy. I. A study of complexity and DNA content of the foci].

Newly replicated DNA segments (RDS) have been shown to form discrete foci in the mammalian nucleus. Comparison of the number of such foci in formaldehyde-fixed cell nucleus with estimated number of simultaneously active replication forks (RF) suggests that each replication focus contains a cluster of about 10 to 20 closely associated RF. That implied the cluster of synchronously activated replicons as the primary unit of mammalian DNA replication. It still remains unclear whether such clustering of RF does mean adjacency of the replicons in a genomic location (structural clustering, model 1), or it arises from transient clustering of the replicons from different DNA domains at the functioning replication machinery (functional clustering, model 2). In this study we used conventional fluorescence microscopy of the hypotonically treated nuclei preparations to investigate replication foci at the optical resolution limit. Human K562 cells were labeled with 5'-iododeoxyuridine for different time periods. We synchronized the cell culture with hydroxyurea to be able to measure an average increase in DNA content during labeling period using DNA cytometry. Under these conditions, RDS appear as multiple small foci (mini-foci, MF). Further studies revealed that most of such mini-foci of replication represent optical diffraction spots, which are standard in size and different in brightness. The number of the "spots" and variation of their brightness mostly depend on the extent of hypotonic treatment. Flow cytometry control of the synchronized cells peak movement allowed us to measure mean DNA content of the MF. In case of most effective hypotonic treatment, a MF contains about 40 Kbp of labeled DNA, and the general number of the MF approaches the number of replicons that are simultaneously active in a given moment of S-phase. Influence of the effect of hypotonic treatment on overall number of observed MF suggests that replication foci in early and mid S-phase cells do not represent stable structures, but rather arise from functional clustering of comparatively distant replicating regions, thus supporting model 2.

Cell Line, Tumor↗

PubMed2004

[Cell shrinkage during apoptosis is not obligatory. Apoptosis of U937 cells induced by staurosporine and etoposide].

A study was made of apoptotic cell shrinkage, which is generally believed to be a hallmark of apoptosis. The two conventional models of apoptosis were used for examination of changes in cell water balance--one is apoptosis caused in human lymphoma cell line U937 by staurosporine, and the other by etoposide. Intracellular water was determined by measuring buoyant density of cells in continuous Percoll gradient. Apoptosis was recognized by microscopy and flow cytometry. Apoptosis caused by staurosporine (1 microM, 4 h) was found to be associated with a decrease in cell water content by almost 24%. In contrast, no decrease in cell water content was observed in U937 cells incubated with etoposide (50 microM, 4 h), in spite of the number of features suggesting the presence of apoptosis, such as the appearance of apoptotic bodies, chromatin condensation and fragmentation and disappearance of S-phase cells in DNA histogram. It is concluded that definition of apoptosis as "shrinkage-necrosis" (Kerr, 1971) needs correcting: the distinction of apoptotic cells involves the absence of swelling, rather than cell shrinkage.

Antineoplastic Agents, Phytogenic↗

PubMed2003

[Effect of narrow fractions of chromatin non-histone proteins on the expression of membrane tumor-associated antigen MA-50 and phosphorylation of proteins of cultured rat hepatocytes].

As earlier reported, the main component of narrow fractions of chromosomal non-histone proteins (NHP) of kidney and of Zaidel hepatoma cells has its own protein kinase activity, and is identified as a heteroorgan NHP-antigen, which is intrinsic to the definite renal tissue and absent in the liver. Effects of narrow fractions of kidney and Zaidel hepatoma NHP on biosynthetic processes and sizes of hepatocytes were studied in vitro. It has been shown that as a result of a 5 h incubation of rat hepatocytes with a narrow fraction of renal NHP the proportion of small hepatocytes increases approximately by 12% as compared with that of cells cultivated without NHP. Besides, binding of organ-specific anti-kidney immune serum with a small hepatocyte population rises by more than 20%, which results from the expression of tumor-associated heteroorgan kidney-specific antigen on the hepatocyte surface. According to immunoprecipitation and subsequent electrophoresis, the molecular mass of a membrane heteroorgan antigen on the surface of hepatocytes amounts approximately to 65 kDa, and an active phosphorylation of cellular proteins takes place. The same effect on hepatocytes is produced by a narrow NHP fraction of chromatin of Zaidel hepatoma cells, whereas no phosphorylation is observed in the presence of liver NHP as well as in the absence of NHP. It is suggested that the heteroorgan NHP-antigen induces biosynthetic processes including synthesis of membrane tumorassociated antigen on the surface of hepatocytes cultivated in vitro by activation of cellular protein phosphorylation, which can lead to changes in size of cultivated cells.

Animals↗

PubMed2003

[Genetic variation in two forms of the common spadefoot toad Pelobates fuscus (Pelobatidae, Anura, Amphibia) distinguished by genome size].

Genetic differences (presumed 23 loci) between two cryptic forms of Pelobates fuscus, differing in genome size, were examined by means of polyacrylamide-gel electrophoresis. This method allowed to discriminate between these forms. Average genetic distance (DN) between both the forms was equal to 0.311, ranging from 0.055 to 0.563. As a rule, differences within these groups were smaller (0.021-0.388). The data show obvious genetic differentiation between these two cryptic forms of P. fuscus. Differences between these forms and P. syriacus were significantly higher (in average 0.943). Genetic distances in relation to speciation and species concepts are discussed.

Animals↗

PubMed2003

[Water and ion balance in rat thymocytes under apoptosis induced with dexamethasone or etoposide. Ion-osmotic model of cell volume decrease].

Cell ion and water balance was studied with respect to analysis of the osmotic model of apoptotic volume decrease (AVD) in rat thymocytes under dexamethasone (1 microM, 4-6 h) or etoposide (50 microM, 5 h) treatment. Intracellular water content was determined by measurement of cell buoyant density in continuous Percoll gradient, while intracellular potassium and sodium contents were determined by flame emission analysis. Apoptosis was verified by an increase in cell buoyant density, fluorescence of cells stained with Acridine orange and Ethidium bromide (flow cytometry), by changes in the cell cycle and the appearance of sub-diploid peak in the DNA histogram (flow cytometry), and by a decrease in cell size examined with light microscope. A separate fraction of dense cells with reduced size was found to appear after dexamethasone or etoposide treatment. This fraction was considered as apoptotic. An increase in buoyant density of apoptotic cells corresponded to a decrease in cell water content. In apoptotic cells vs. cells with normal buoyant density, the intracellular potassium content was lower, but sodium content was higher. The sum of potassium and sodium contents was lower in apoptotic cells. Taken into account the loss of anions, associated with the loss of cations, the bulk decrease in ions content has been sufficient to be accounted for cell volume decrease on the basis of the ion-osmotic model.

Animals↗

PubMed2000

[Variability of the level of thermoresistance as an indicator of the functional status of a cell].

Effect of acclimating temperature on the thermoresistance of isolated ciliated gill epithelium of Anodonta anatina was studied. One strip of gills from each mussel was used to determine the initial level of thermoresistance (survival time at 40 degrees C). Other strips were kept at 24 degrees C until their death, and their thermoresistance and fluorescence after Ethidium bromide staining were determined at different time intervals. After a short exposure at 24 degrees C the mean level of thermoresistance of the epithelium increased. The individual shift in the value and direction of cell thermoresistance in different mussels negatively correlated with its initial level. It resulted in narrowing the extent of individual variability of the level of thermoresistance. The prolongation of exposure at 24 degrees C decreased the mean level of thermoresistance, disturbed the negative correlation, and increased the variability of thermoresistance level. The value of cell fluorescence remained constant within 48 h. The increase in fluorescence was observed 12 h after reducing the mean thermoresistance level. Hence, the dynamics of variability in the thermoresistance level is a most sensitive indication of the cell functional state.

Animals↗

PubMed1998

[Organization of DNA replication domains in S-phase nuclei of human cells].

Each chromosome of eukaryotic cells contains multiple units of DNA replication that are activated during S-phase of cell cycle according to a definite program. It is considered at present that the main independent units of replication in mammalian cells represent groups of 20-25 adjacent synchronously activated small (with the average size 100 kbp) replicons. After labelling of nascent DNA with nonradioactive DNA precursors and immunofluorescent staining of incorporated label, discrete replication domains (RDs) are detected in S-phase nuclei. It is assumed that each RD is formed by a single group of synchronously activated small replicons. Since the average rate of replication fork movement is 2 kbp/min, a group of small replicons should finish DNA synthesis within 25 min, and only during this time one RD should incorporate the replicative label. We have studied the duration of DNA synthesis in individual RDs in S-phase human cells using double replicative labelling that can be detected in the nucleus by specific reagents. Our results indicate that in the main fraction of RDs DNA synthesis lasts more than 90 min, that contradicts the generally accepted model of organization of replication units in mammalian cells (Hand, 1978), but is in agreement with an alternative model, according to which the main replication units are single or clustered big replicons more than 300 kbp in size (Liapunova, 1994).

Cell Nucleus↗

PubMed1998

[Precise DNA cytometry: investigation of individual variability in animal genome size].

The variability of genome size was studied in animal populations and in cell populations of different animal species by means of DNA flow cytometry with the precision level of several tenths of percent. For populations of frog Rana esculenta and laboratory mouse lines C57B1 and CBA the analysis was made with cells of different tissues: erythrocytes for R. esculenta, splenocytes for mice and haploid cells of testes for both species. The results of DNA cytometry, obtained with cells of different species, were shown to be correlated, which indicates the objectivity of individual intrapopulation differences in the genome size recorded with DNA flow cytometry. The level of variability (expressed as CV) was 0.3-0.4% for the population of frogs, and 0.2-0.3% for mouse lines. The analysis of genome size variability in cell populations of different animal species revealed a relationship between the variability level and the genome size: the coefficient of variance of the peak of DNA histogram was inversely related to the square root of genome size. The latter effect may be explained by fluctuations of a measured multicomponent object, but it is still unclear whether these fluctuations could be related to the genome size or to pecularities of chromatin structure. It is concluded that the method of flow DNA cytometry may be effective for studying individual differences in the genome size.

Animals↗

PubMed1996

[The heterogeneity of cell populations by the cytochemical characteristics of the cellular chromatin].

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.

Animals↗

PubMed1993

[The measurement of cell concentration and size using the AOD-101 cytometer].

A particle sizing counter, elaborated by the Institute of Cytology and Scientific-Industry Union "Analytpribor", was evaluated for its effectiveness in analysing different cell suspensions. The mean error of cell concentration measurement is about 3% within the 1-15 x 10(4) ml-1 interval. Cells can be found in suspension at a concentration of 2 x 10(2) ml-1. Cell size can be measured reproducibly within 10% for the interval 3-150 microns. The absolute value of cell size can be obtained after the device graduation with independently sized cells. Such a graduation differs by 5-10% from the graduation with latexes.

Animals↗

PubMed1993

[The dynamic proliferative activity of mouse bone marrow cells during the suppression and recovery of hemopoiesis after 5-fluorouracil administration to the animals].

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.

Animals↗

PubMed1992

[The effect of 3-aminobenzamide on the mitotic cycle of Chinese hamster cells cultured on a medium with 5-bromodeoxyuridine following ionizing radiation action].

A specific inhibitor of poly(ADP-ribose)polymerase-3-aminobenzamide (6 mM) has been shown to: 1) reduce survival of non-irradiated CHO-K1 cells, cultivated in medium containing 5-bromodeoxyuridine (10 mkM, BDU cells), and increase their radiosensitivity; 2) induce G2 delay in BDU cells while progressing through the cell cycle as analysed by the DNA flow cytometry; 3) increase to a great degree G2 delay in X-irradiated BDU cells. 3-Aminobenzamide is primarily effective when it is present during the first or two first cell cycles after the initial addition of BDU. The above data confirm the involvement, presumably an indirect one, of ADP-ribosylation in the DNA repair through affecting the chromatin structure.

Animals↗

PubMed1992

[DNA synthesis and content in human decidual cells at different stages of differentiation based on flow cytometry data].

Flow cytometry analysis of the DNA content of human decidual cells at the physiologically normal pregnancy and in the case of toxicosis was carried out. During the normal pregnancy DNA-histogram parameters were seen to vary: the number of S-phase cells decreased, the coefficient of variation of the G1/0 peak increased. These alterations correlated positively with the increase in the share of decidual cells with properties of terminally differentiated cells. The most pronounced quantitative alterations in variability of DNA content in G1/0 cells were observed in cases of toxicosis of pregnancy. Phenomena of variability of the nuclear DNA in the terminally differentiated decidual cells is considered to be a sign of cell death through apoptosis.

Adolescent↗

PubMed1992

[Changes in the frequency of cells with micronuclei in cell populations of rat transplantable rhabdomyosarcoma RA-2 as a result of selection for an increased and a decreased frequency of such cells].

Artificial selection for increasing and decreasing frequencies of cells with micronuclei (FCM) was conducted in populations of cell clones of the rat transplantable RA-2 rabdomyosarcoma. The selection was effective in both the opposite directions. The average FCM increased from 3.3 +/- 0.2 to 6.9 +/- 0.6% and decreased from 3.3 +/- 0.2 to 1.6 +/- 0.2%. Heritability coefficient, h2, varied from 0.2 to 0.4. In the cell population with increased FCM, 37% of anaphases and early telophases had lagged chromosomes and fragments. In contrast, in the cell population with decreased FCM, lagging were observed in 11% of cases. The DNA-content in G1 cell varied greatly in cell population with increased FCM (P < 0.01). The selection for increased FCM has led to a significant decrease in metastatic capacities of cells.

Animals↗

PubMed1991

[An automated scintillation counter for poorly contrasting microparticles].

A cell scintillator intended for analysis of the disperse composition and concentration of poor contrast biologic objects suspended in transparent liquid media has been designed at the Analitpribor Research and Production Amalgamation in Tbilisi for the Cytology Institute of the USSR Academy of Sciences in Leningrad. The apparatus is based on light blocking and hydro-focussing physical principles. Automated system of the apparatus calibration permits measurements of the particles 3 to 150 microns in size at the level of 10%. The mean error of cell concentration estimation within the range of 10000-150000 cell/ml is 3%.

Cell Count↗

PubMed1990

[Recording of the free calcium content of the peripheral blood leukocytes in allergic diseases in children].

Flow cytometry was used to analyse the free calcium content in leukocytes of peripheral blood in children with allergic diseases, both before and after contacting with allergens and mediators of anaphylaxis. Computer analysis with a special mathematical program was used to evaluate the gravity-centre coordinate of the histograms obtained. More than a 10% shift to the right on the X-axis was diagnosed as an increased sensitivity of peripheral blood cells to the allergens or mediators of anaphylaxis. Good correlations were obtained between our data and different provocation tests, usually used in practical allergology.

Adolescent↗