Biomedical subjects

G I Stein

Publications and source records attributed to G I Stein.

9 recordsLinked to original sources

PubMed2005

Whole-genome chromosome distribution during nuclear fragmentation of giant trophoblast cells of Microtus rossiaemeridionalis studied with the use of gonosomal chromatin arrangement.

Gonosomal chromatin bodies (GCBs), i.e. blocks of condensed chromatin consisting of heterochromatized region of the sex chromosomes of the field vole M. rossiaemeridionalis, were used as a natural interphase chromosome marker in order to clarify the regularities of GCB rearrangement during nuclear fragmentation of secondary giant trophoblast cells (SGTCs) at the end of their differentiation. Cytophotometrical measurements of DNA content in the nuclei, nuclear fragments and simultaneously in the GCBs were made in the secondary giant SGTCs of field vole M. rossiaemeridionalis. In most cases 1 to 2 GCBs get into the nuclear fragments at different ploidy levels. In the nuclear fragments, GCB DNA content decreased mostly proportionally to DNA content in the whole fragments corresponding to 2c, 4c and 8c. The data obtained demonstrate a regular whole-genome chromosome distribution into nuclear fragments. A possible mechanism of nuclear fragmentation that largely ensures a balanced genome in nuclear fragments is discussed.

Animals↗

PubMed2000

Trophoblast cell invasiveness and capability for the cell and genome reproduction in rat placenta.

Using 3H-thymidine labeling and cytophotometric DNA content measurement in nuclei and mitotic figures, proliferative activity and genome reproduction peculiarities have been studied in highly invasive, primary and secondary giant trophoblast cells (pGTCs and sGTCs, respectively) as well as in the low invasive junctional zone and labyrinth trophoblast cells (JTCs and LTCs) of rat placenta. It has been shown that different extent and patterns of phagocytic activity of pGTCs and sGTCs correspond to different developmental stages. An inverse relationship has been observed between capability for mitoses and invasive and phagocytic activities. The pGTCs and sGTCs lose their mitotic activity from the start of their differentiation. Nevertheless, they continue reproduction of their genome and undergo a series of endoreduplication cycles to reach the ploidy degree of 256-1024c. In contrast, the JTCs and LTCs have, as a rule, no invasive and phagocytic activities, while preserving proliferative properties up to 15 day of gestation. They undergo initial polyploidization via uncompleted polyploidizing mitoses up to octaploid level and then pass to the endoreduplication cycle that excludes mitoses. Such a way of cell reproduction has been suggested to play a protective role, as it rules out contacts of the trophoblast cell genome with chromosomes of the phagocyted allogenic maternal tissue.

Animals↗

PubMed1998

Functional activity of human hepatocytes under traumatic disease.

Absorption and fluorescent cytophotometry techniques were applied to studies of RNA as well as of total glycogen and its fractions as the parameters of functional activity of the hepatocytes in patients with severe mechanical trauma, both with and without autointoxication (AI). Slides were stained with gallocyanine-chromalums to determine the RNA content and were processed by the fluorescent PAS-reaction for the glycogen content. To trace the dynamics of RNA and glycogen contents in the liver punction biopsies were done in the same patients. A quick increase in the RNA content took place in both groups of patients at the first period (within the first 3 days) of traumatic disease. At the second period of disease the hepatocyte RNA content in patients without AI was found to decrease up to the initial level whereas that in patients with AI increased on the average by 36% of the initial values. The total glycogen content in hepatocytes of all the patients changed insignificantly in the course of disease but its labile fraction in patients with AI decreased to 70% of the total. The increase of hepatocyte synthetic activity and the maintenance of the high glycogen level are indicative of the large compensatory potential of the liver that enables it to carry an intensive functional load under AI conditions.

Endotoxins↗

PubMed1998

[Potential of the image analyzer "videotest" for performing microphotometric study in cytology].

Precision features of image analyser "Videotest" and possibilities of its applications for cytophotometric investigations have been analysed. It has been shown that a photometric feature is linear at least to optical density 1.1. Cytophotometry of the Feulgen stained rat hepatocyte nuclei has been performed. Coefficients of variation of DNA for 2c, 4c and 8c nuclei are 7.72, 7.65 and 6.50%, respectively, and ratios between average values of these nuclei are 1.00:2.06:4.12. Possible causes of errors of digital television equipment for cytophotometry are discussed.

Animals↗

PubMed1997

[Units of DNA replication in S-phase human cells].

Current methods of physical mapping allow the estimation of genomic distances (i.e. DNA contents) from linear distances between DNA markers in interphase nuclei, and in this study we estimated the size of focal centers of DNA replication in cultured S-phase human cells. Our results indicate that the conformation of S-phase chromosome fibres in the range of contour lengths 0.1-3.0 microns fits the random walk model and, therefore, the quantitative methods of interphase mapping can be applied to the estimation of sizes of replication units. The obtained data show the existence of multiple non-clustered small units less than 150 kb in size, equivalent to small replicons detected by fiber DNA radioautography, and also a significant fraction of big units more than 500 kb in size, representing groups of small replicons and/or big replicons. These big units are detected as chains of small replication foci, probably reflecting the structural chromatin organization in well-known loop domains, since the experimentally induced decrease of replicons to the average size 12 kb does not lead to any change in the pattern of indicated chains.

Adenocarcinoma↗

PubMed1996

Quantitative analysis of glycogen content in hepatocytes of portal and central lobule zones of normal human liver and in patients with chronic hepatitis of different etiology.

Glycogen content was determined in hepatocytes of different lobule zones of the normal human liver (23 patients without any liver pathology) and the liver of patients with chronic viral B hepatitis (30 patients) and chronic alcohol hepatitis (28 patients). All the patients were males and aged between 17-50 years. Quantitative analysis of the glycogen content in hepatocytes of portal and central lobule zones was carried out in sections of the human liver (material of functional biopsies) stained with PAS-reaction. The measurements were carried out using an image analyser 'Magiscan' which allows combined cytophotometric analysis of a substance in cells and determination of the cell localization in tissue. The results showed significant differences of the glycogen content in different lobule zones in the normal liver and in the liver in chronic viral and alcohol hepatitis. Ratios of glycogen content in hepatocytes of the portal and the central zones of liver lobule were 1.128 +/- 0.004 and 1.061 +/- 0.003 in normal human liver, and liver of patients with chronic viral hepatitis respectively, i.e. the glycogen content in hepatocytes of the portal lobule zone was much higher than in the central lobule zone in the normal liver and in the liver of patients with chronic viral B hepatitis. The ratio in patients with chronic alcohol hepatitis was less than 1.0 (0.930 +/- 0.003), i.e. a significantly higher glycogen content was found in hepatocytes of the central liver lobule zone. Possible mechanisms of this phenomenon are discussed. Thus, the pattern of the glycogen content in hepatocytes of different lobule zones can be used as an indicator of etiology of chronic hepatitis.

Adolescent↗

PubMed1993

Human hepatocyte polyploidization kinetics in the course of life cycle.

The processes of polyploidization in normal human liver parenchyma from 155 individuals aged between 1 day and 92 years were investigated by Feulgen-DNA cytophotometry. It was shown that polyploid hepatocytes appear in individuals from 1 to 5 years old. Up to the age of 50 years the accumulation rate of binucleate and polyploid cells is very slow, but subsequently hepatocyte polyploidization is intensified, and in patients aged 86-92 years the relative number of cells with polyploid nuclei is about 27%. Only a few hepatocytes in the normal human liver reach 16C and 8C x 2 ploidy levels for mononucleate and binucleate cells respectively. Using a mathematical modeling method, it was shown that during postnatal liver growth the polyploidization process in human liver is similar to that in the rat, and that polyploid cells are formed mainly from binucleate cells. As in rats, prior to an increase in ploidy level, diploid human hepatocytes can pass several times through the usual mitotic cycles maintaining their initial ploidy level. After birth, only one in ten hepatocytes starting DNA synthesis enters the polyploidization process. At maturity about 60% of 2C-hepatocytes starting DNA synthesis divide by conventional mitosis, the rest dividing by acytokinetic mitosis leading to the formation of binucleate cells. During ageing the probability of hepatocyte polyploidization increases and in this period there are two polyploid or binucleate cells for every diploid dividing by conventional mitosis.

Adolescent↗

PubMed1992

A method for investigating hepatocyte polyploidization kinetics during postnatal development in mammals.

A method for investigating weakly-proliferating cell populations of liver parenchyma on the basis of a quantitative analysis of hepatocyte polyploidization during postnatal development is described. The method uses a mathematical model which characterizes the hepatocyte polyploidization process, and incorporates data concerning the time course for relative frequencies of hepatocytes in different ploidy classes. As a result of these measurements and calculations for rat liver, transition rates of hepatocytes (the relative number of cells during a given time unit) from one ploidy class to another, and a coefficient for the reduction of hepatocyte mitotic activity with an increase in its ploidy class were obtained. Calculated curves show a good correspondence with the real process of hepatocyte frequency changes as they relate to changes in the age of the animals. To check this method, experiments investigating time changes of autoradiographic label content in the different ploidy classes of hepatocytes were carried out. By mathematically modeling the label diluting process resulting from cell proliferation and polyploidization, transition rates of hepatocytes were calculated, and they reflect values calculated from the model according to changes in occurrence frequencies.

Animals↗

PubMed1992

The metabolic zonation of glycogen synthesis in rat liver after fasting and refeeding.

The quantitative analysis of total glycogen and two fractions of the glycogen content was made by means of cytophotometry in hepatocytes with respect to the portal and central zones of the liver lobule after 48 hr starvation and 15, 30, 60, 120 min after refeeding using the Magiscan image analyzer. It was shown that glycogen content was minimal after 48 hr starvation, although a few cells of the central zone contained a noticeable glycogen quantity. Glycogen synthesis initiation was observed after 15 min refeeding. Glycogen synthesis has been characterized by an increasing glycogen content in the portal zone of the liver lobule compared to the pericentral zone, and this difference increased with time. The distinctive morphological changes were observed in the total glycogen content as well as fractions with different optical density in the process of glycogen synthesis after starvation of rats.

Animals↗