Synchronization of cell proliferation in sarcoma 37 of mice by hydroxyurea

The synchronizing action of hydroxyurea on the passage of sarcoma 37 cells through the S phase and mitosis was investigated in mice, allowing for diurnal fluctuations in mitotic activity and the index of labeled nuclei. The degree of synchronization was estimated from changes in the number of proliferating or labeled cells and the rate of change of synchronization. The tumor consisted of at least two cell populations in which variations in the number of cells both in the S period and also, probably, in mitosis were out of phase. The degree of artificial synchronization of the cells in mitosis based on the rate of change of synchronization was much higher than the natural level in the tumor not divided into separate populations. However, the number of cells undergoing artificial synchronization was not significantly different not only from the number of cells in the tumor undivided into separate populations, but also from the number of cells naturally synchronized in one of the populations. A possible explanation of this fact is that hydroxyurea acted on only one group of cells, for fluctuations in the number of DNA-synthesizing cells in the separate populations also were out of phase.Laboratory of Growth and Development, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. Department of General Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 11, pp. 1352–1354, November, 1976.     

Effect of absence of polyploid hepatocytes on regeneration in the liver

An autoradiographic study with [³H]thymidine showed that the hepatocytes of young sexually mature guinea pigs commence the phase of DNA synthesis 25 h after partial hepatectomy. Peaks of the number of labeled nuclei were found 30, 45, and 60 h after the operation. Two waves of mitoses were found by counting mitotic figures in squash preparations: 40 and 55 h after hepatectomy. A cytophotometric study of the DNA content showed that practically all the mononuclear and binuclear hepatocytes contained diploid nuclei 3 and 5 days after the operation. By the end of the 7th day of regeneration there were 6% of mononuclear tetraploid cells. The number of binuclear cells fell during the period of regeneration studied from 16 to 8%. It is concluded that the principal cytological mechanism of liver regeneration in guinea pigs is normal mitosis terminating in separation of the cells.Department of Histology and Embryology, Second Moscow Medical Institute. Laboratory of Functional Morphology of the Chromosomes, Institute of Molecular Biology, Academy of Sciences of the USSR. Laboratory of Cytology, Institute of Developmental Biology, Academy of Sciences of the USSR. (Presented by Academician of the Academy of Medical Sciences of the USSR Yu. M. Lopukhin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 8, pp. 221–224, August, 1977.     

Investigation of the cytostatic action of cyclophosphamide on esophageal tumors and epithelium in mice

The cytostatic action of cyclophosphamide on sarcoma 37 and the esophageal epithelium was investigated in albino mice by determination of the diurnal rhythms of mitotic activity and the number of labeled nuclei. Tumor cells were shown to be most sensitive to the inhibitory action of the compound evidently in the G₁ phase at the beginning of the S phase. As the period of DNA synthesis came to an end, the resistance of the cells to the cytostatic increased. Cells in the G₁ phase of the mitotic cycle in the esophageal epithelium are sensitive to the inhibitory action of cyclophosphamide.Laboratory of Growth and Development, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 11, pp. 593–595, November, 1977.     

Comparative study of the action of ethimizole and hydrocortisone on proliferative activity and protein synthesis in epithelial cells of the tongue and liver

Unlike hydrocortisone, ethimizole stimulated mitotic activity of the epithelial cells of the tongue and liver 6 h after its administration. The decrease in the number of mitoses in the hepatocytes after 12 h was due to the action of both substances on DNA synthesis and not to a disturbance of the entry of the cells into mitosis. Stimulation of protein synthesis was detected by autoradiographic and biochemical methods following the action of hydrocortisone and ethimizole at the maximum of inhibition of mitosis.Laboratory of Experimental Histology, Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR S. V. Anichkov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 3, pp. 348–350, March, 1977.     

Diurnal rhythm of mitotic activity,DNA synthesis,and duration of mitoses in mouse bone marrow cells

Cells of the myeloid and erythroid series of mouse bone marrow are characterized by a well-defined diurnal rhythm of mitotic activity and of DNA synthesis, with coincidence between the times of maxima of the number of mitoses and of DNA-synthesizing cells (in the afternoon and night) and of their minima (in the morning and evening). The increase in mitotic activity is connected with the entry of large numbers of cells into mitosis and not with an increase in the duration of mitosis.High Energy Laboratory, N. N. Petrov Institute of Oncology, Ministry of Health of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR A. I. Serebrov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 5, pp. 594–596, May, 1976.     

Cytochemical investigation of dynamics of RNA synthesis demonstrated in metaphase chromosomes of HeLa cells

The dynamics of synthesis of DNA and chromosomal RNA, demonstrated in metaphase chromosomes of HeLa cells, was investigated by methods of selective extraction of cells in mitosis from the monolayer and pulse labeling. The results showed that chromosomal RNA is itself synthesized chiefly at the end of the G₁- and beginning of the S-period. The synthesis of chromosomal RNA was found in the G₂-period or during mitosis.Laboratory of Histochemistry and Molecular Pathology, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 79, No. 3, pp. 94–97, March, 1975.     

Effect of cyclic AMP on mitosis in the esophageal epithelium of mice with tumors

Mitotic activity and the number of DNA-synthesizing cells were studied in the epithelium of the esophageal mucosa of albino mice with tumors during the 24 h after administration of dibutyrylcyclic 3,5-AMP. Injection of the compound leads to delay of the cells in the G₂ phase of the mitotic cycle and to an increase in the duration of mitosis during the first few hours of the experiments, without changing the total number of cells passing through the mitotic cycle in the 24-h period.Department of Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 8, pp. 215–217, August, 1977.     

Changes in intracellular ribonuclease activity in the rat liver during inhibition of protein synthesis by cycloheximide

Injection of cycloheximide into rats was shown not to change the acid and alkaline ribonuclease (RNase) activity in the cytoplasm of liver cells. Meanwhile inhibition of protein synthesis by cycloheximide led to a decrease in RNase activity of microsomes and membrane-bound polysomes. RNase activity of free polysomes in liver cells was considerably increased after administration of cycloheximide.Laboratory of Enzymology, Academy of Medical Sciences of the USSR. Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. Presented by Academician of the Academy of Medical Sciences of the USSR S. S. Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 2, pp. 168–170, February, 1980.     

Some aspects of structural disturbances in the DNP complex when damaged by N-nitroso-N-methylurea

The effect of solubilization of deoxyribonucleoproteins (DNP) in a medium of near-physiological ionic strength after treatment with the mutagen N-nitroso-N-methylurea (NMU) is highly dependent on the NMU concentration. To convert DNP into a soluble state, the critical number of groups in the DNA and protein must evidently be modified. On the basis of data obtained by the circular dichroism method and by viscosimetry it is concluded that after treatment with NMU the DNP complex becomes soluble in solvents with near-physiological ionic strength largely as a result of labilization and dissociation of the DNA-protein bonds.Laboratory of Biophysics, Institute of Medical Genetics, Academy of Medical Sciences of the USSR. Sector of Kinetics of Chemical and Biological Processes, Institute of Chemical Physics, Academy of Sciences of the USSR. Laboratory of Physical Methods of Investigation, D. I. Ivanovskii Institute of Virology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR S. S Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 6, pp. 674–677, June, 1976.     

Physicochemical changes in DNA and DNP induced by potassium cyanate

The effect of KNCO on the structural integrity of salt solutions of DNP was investigated. The use of sedimentation, viscosimetric, and circular dichroism methods showed that KNCO does not cause degradation of the polynucleotide strands of DNA but it weakens the bond between DNA and proteinLaboratory of Biophysics, Institute of Medical Genetics, Academy of Medical Sciences of the USSR. Sector of Kinetics of Chemical and Biological Processes, Institute of Chemical Physics, Academy of Sciences of the USSR. Laboratory of Physical Methods of Investigation, D. I. Ivanovskii Institute of Virology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR S. S. Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 4, pp. 425–427, April, 1976.     

Response of anterior pituitary cells after acute cooling in rats

The anterior lobe of the pituitary (ALP) of rats exposed to general cooling to –10°C for 6 min was investigated by histological and autoradiographic methods. The diurnal cycle of changes in the functional state of the glandular cells of ALP, the number of mitoses, and the number of labeled cells synthesizing DNA was examined 3, 6, 12, 18, and 24 h after cooling. Marked activation of thyrotrophs and doubling of the number of mitoses were observed 12 h after cooling, with no change in the index of labeled cells in the course of 24 h. The results showed that the stressor response to cold in rats is characterized by potentiation of the thyrotrophic function and by acceleration of mitosis in the cells of ALP.Laboratory of Neutron Research, B. P. Konstantinov Leningrad Institute of Nuclear Physics, Academy of Sciences of the USSR. (Presented by Academician of the Academy of Medical Sciences of the USSR L. M. Shabad.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 6, pp. 734–736, June, 1978.     

Adjuvant action of fragments of the IgG molecule present in the serum of partially hepatectomized rabbits

Fragments of the IgG molecule, related to Fab, present in the blood serum of partially hepatectomized rabbits, have the property of intensifying the immune response of rabbits through xenogeneic erythrocytes. After simultaneous injection of sheep's erythrocytes and the Fab-like fragment into rabbits there was an increase in the number of antibody-producing cells in the spleen and in the titers of 19S and 7S hemagglutinins.Kursk Medical Institute. N. F. Gamaleya Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR G. V. Vygodchikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 2, pp. 206–208, February, 1976.     

Diurnal rhythm of mitosis and in number of DNA-synthesizing cells after adrenalectomy in mice

Diurnal changes in the number of DNA-synthesizing cells and in the number of mitoses were studied in the corneal epithelium and liver of intact and adrenalectomized mice. The curve of diurnal changes in the number of labeled nuclei in the corneal epithelium of the mice after adrenalectomy became bimodal and the amplitude of fluctuations in the mitotic index in the course of the 24-h period increased sharply compared with the control. The rhythm of DNA synthesis in the liver was similar in the control and experimental series, and the rhythm of mitosis in the experimental animals became biphasic in character. Adrenalectomy thus disturbs the phase structure of the rhythms of DNA synthesis and of mitosis in the tissues studied.Department of General Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 6, pp. 740–742, June, 1976.     

T- and B-lymphocytes of guinea pigs sensitized with ragweed pollen

The number of T and B rosette-forming cells (T- and B-RFC) in guinea pigs was determined after sensitization with ragweed (Ambrosia artemisifolia L.) pollen. The number of B-RFC in the regional lymph nodes in the early stages of sensitization was shown to be 4 times greater than the number of B-RFC in normal animals. The functional capacity of the T-cells, assessed by the rosette-formation test, showed a more marked change after sensitization than the corresponding capacity of the B-cells.Allergologic Research Laboratory, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR S. S. Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 2, pp. 187–189, February, 1979.     

Effect of repeated cooling on the state of the adrenals and proliferation of the corneal epithelium in albino rats

The effect of repeated cooling on the state of the adrenals and on the mitotic cycle and number of DNA-synthesizing nuclei in the corneal epithelium was studied in albino rats. The animals were cooled by a contact method to a body temperature of 28°C and exposed at that temperature 1 h daily for 5 days. Marked activation of the adrenals was observed: The weight of the glands was doubled, their cholesterol concentration reduced by two-thirds, their blood 11-hydroxycorticosteroid level increased fourfold, and their adrenalin excretion stimulated. The mean number of mitoses in the cornea was reduced by half. The depression was not connected with any change in the rate of mitosis but was due to delay in interphases. There was no change in the level of pathological mitoses. Chronic exposure to stress was not accompanied by any change in the number of DNA-synthesizing nuclei or the intensity of DNA synthesis.Central Research Laboratory, Khabarovsk Medical Institute. Laboratory of Cytology, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 7, pp. 87–89, July, 1979.     

Duration of the mitotic cycle of mouse liver cells at different stages of carcinogenesis induced by orthoaminoazotoluene

Mice were given orthoaminoazotoluene for 9 months. The duration of the G₂ and S periods of the mitotic cycle was determined by an autoradiographic method and the duration of mitosis was determined by a stathmokinetic method using colcemid for hepatocytes from intact liver and for cells of adenomatous nodules and primary hepatomas. The duration of the S period for cells of the intact liver and of the adenomatous nodules was shown to be identical (13.8 and 13.9 h respectively), whereas for hepatoma cells it was reduced to 12.8 h. The duration of the G₂ period did not change substantially in the course of carcinogenesis and ranged from 2.2 to 2.7 h. The mean diurnal duration of mitosis likewise was unchanged at about 1 h. The increase in the number of mitoses and of DNA-synthesizing cells in hepatomas results from the entry of a larger number of cells into mitosis and into the S period and not from an increase in the duration of the M- and S periods of the mitotic cycle.Department of Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 1, pp. 61–64, January, 1978.     

Effect of chronic pyrogenal stress on the mitotic regime and number of DNA-synthesizing cells in the corneal and lingual epithelium of albino rats

The effect of prolonged stress on the mitotic regime and number of DNA-synthesizing cells in the corneal and lingual epithelium was studied in response to pyrogenal. Injection of pyrogenal for 5 days caused a decrease of 41% in the number of mitoses in the corneal and lingual epithelium. The decrease in the number of dividing cells did not correlate with changes in the rate of mitosis. The number of pathological mitoses in the corneal epithelium of intact rats remained unchanged during stress. The index of labeled nuclei in the corneal and lingual epithelium of the control rats was 12.6 and 10.8 respectively, which did not differ significantly from their values in the experimental animals (12.2 and 12.2).Central Research Laboratory, Khabarovsk Medical Institute. Laboratory of Cytology, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 8, pp. 248–250, August, 1978.     

Synchronizing action of cyclic AMP on the mitotic cycle of ehrlich's ascites carcinoma cells

The number of mitoses and of DNA-synthesizing cells in an Ehrlich's ascites carcinoma was studied during the 24 h after injection of dibutyryl cyclic 3,5-adenosine monophosphate. As a result of preprophase inhibition and, probably, of stimulation of entry of the cells into the synthetic period, a large number of cells commences mitosis simultaneously 8 h after the injection. The resulting synchronization of mitosis in the cell population of the tumor is evaluated.Department of General Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 1, pp. 66–68, January, 1976.     

Mechanisms of polyploidization of mouse cardiomyocytes

Most ventricular cardiomyocytes in mice aged 5–6 days are polyploid cells. By this time 60% of the cardiomyocytes have become binuclear and a further 10% have become mononuclear polyploid cells. Binuclear cardiomyocytes are formed as a result of acytokinetic mitosis, mononuclear tetraploid cells as a result of termination of mitosis in the initial phases.Laboratory of Cytology, N. K. Kol'tsov Institute of Developmental Biology, Academy of Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 2, pp. 219–222, February, 1980.     

Blood rheology and microcirculation in the course of acute experimental pancreatitis

Academic Group of Academician of the Academy of Medical Sciences of the USSR. Professor V. S. Savel'ev, A. N. Bakulev Institute of Cardiovascular Surgery, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. S. Savel'ev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 105, No. 1, pp. 106–108, January, 1988.