Cytogenetic changes in the bone marrow cells of long-term irradiated rats]

The occurrence and characteristics of the chromosome structural changes in femur bone marrow cells under continuous irradiation with the exposure rate of 50 R/day within 90 days was followed. The 25% increase in the chromosome aberration frequency was observed within 7 days of the irradiation, and then the aberration rate was constant up to the end of the irradiation (90 days).     

Cloning stem cells in the bone marrow of irradiated mice]

Different amount of intact or irradiated bone marrow from syngenous donors was administered to mice irradiated with a lethal dose. There was revealed a linear dependence of the number of the 8-9-day colonies grown in the bone marrow of the femur on the amount of the administered cells, and an exponential dependence on the irradiation dose. Regularity of the stem cell cloning in the bone marrow was analogous to such in the spleen. Radiosensitivity of the colony-forming units (CFU) differed depending on the site (the spleen, the bone marrow) of their colony formation. The CFU settling in the marrow proved to be more radioresistant (D(0) equalled 160-200 P) in comparison with the CFU settling in the spleen (D(0) constituted 80-100 P). It is supposed that a different radiosensitivity of the CFU was caused by the presence of heterogenic population of the stem cells and also by specific peculiarities of the organ (the spleen, the bone marrow) in which the colonies formed.     

Reaction of bone marrow colony-forming cells in irradiated mice to phlogogenic factors]

The experiments on irradiated mice (600 and 800 r) demonstrated that under the influence of flogogenic factors the quantity of colonies in the spleen increases and their morphological structures change. It is suggested that under the action of the damaging agent the "hypothetic factor" which causes the pointed changes, is formed in the skin.     

Rubidium transport in irradiated vitamin-E-deficient bone marrow cells

We showed previously that the Rb⁺ transport rate in bone marrow cells (BMC) of vitamin-E-deficient mice is significantly lower than that in BMC of euvitaminotic mice. It is now evident that 4 h after whole-body, low-dose (0.01–1.0 Gy) gamma-irradiation of avitaminotic mice, there is an increase in the rate of Rb⁺ transport. This increase is quite pronounced, exceeding at all dose levels the rate of Rb⁺ transport in euvitaminotic mice exposed to the same radiation dose.On leave from the University of Rochester, School of Medicine and Dentistry, Department of Biophysics, Rochester, New York, USA     

Transplantation of bone marrow cells into lethally irradiated mice. Morphology of megakaryocytes]

We described morphological changes of megakaryocytes in the bone marrow and spleen of lethally irradiated mice, dependent on the time lapse following bone marrow transplantation. The functional active megakaryocytes of various morphological types were found to predominate in the tissues on about day 20 to 25.     

Postovariectomy bone marrow changes in irradiated and unirradiated wistar rats

Bilateral ovariectomy of Wistar rats has per se a stimulative effect on the myeloid tissue, determining a hypercellularity of this organ-tissue. On the other hand, under the conditions of a whole-body irradiation with a single dose of 800 r X-rays, bilateral ovariectomy manifests a protective effect on the myeloid tissue preventing the development of hypoplastic, respectively aplastic modifications.     

Sedimentation of alkaline lysates of irradiated rat bone marrow cells

A method has been developed for registration of sedimentation diagrams of alkaline lysates of mammalian cells based on measuring UV-absorption of fractions of linear sucrose gradient during its passage down the flow of UV-cord. DNA sedimentation in alkaline lysates of irradiated bone marrow cells of rats was analyzed. The ability of these cells to repair single-strand breaks during the postirradiation incubation in buffer at 37 degrees C was demonstrated. The proposed method could be applied for screening the compounds affecting the damage and repair of DNA in a cell.     

The effect of serotonin on the hematopoietic stem cells of the bone marrow]

Haemopoietic stem cells content and proliferative activity were studied in the bone marrow of female F1 (CBA x C57Bl6) mice after single (50 mg/kg) and chronic (0.5 mg/kg daily for 7 days) serotonin (S) injections. It is shown that 9-day and 12-day COEs contents in the bone marrow of experimental mice has been increasing for 24 h after single S injection. After chronic S injections twofold increase of 12-day COEs is observed without any increasing of 9-day COEs. Total myelokaryocyte number is increased too. The study of proliferative status by in vitro incubation of bone marrow cells with ARA-C has shown that the numbers of 9-day and 12-day COEs in S-phase have increased both after single and chronic S injections. Possible mechanisms of stimulating effect of S on bone marrow stem cells are discussed.     

Mutagenic effect of the cytostatic drug thaliblastine on rat bone marrow cells when administered alone and in combination with radiation

The cytogenetic analysis was performed in the bone marrow cells of Wistar rats treated with a therapeutic dose of thaliblastine (250 mg/kg) and exposed to gamma-rays (2 Gy). Thaliblastine alone induced chromosome aberrations and polyploid cells. The latter were the result of the stathmokinetic effect of the drug. In contrast to gamma-radiation of 2 Gy thaliblastine elicited a minor mutagenic effect. The cytogenetic effect of the combined treatment is greater than the sum of the two agents delivered separately, the maximum effect of radiation and thaliblastine being exhibited on the 8th and the 12th hour, respectively. The difference between the sum of aberrations after separate treatments and the yield of aberrations after the combined treatment is due to chromatid fragments.     

Micronucleus formation in the bone marrow cells of chronically irradiated mice with subsequent acute gamma irradiation]

With the use of the micronuclear test method it has been shown that mice preirradiated with gamma rays at a low dose rate exhibit a decreased frequency of chromosome aberrations induced in bone marrow cells by subsequent acute exposure to gamma radiation as compared to mice not subjected to preliminary irradiation. Such animals have a higher radioresistance with respect to the survival rate. The results obtained suggest the possibility of induction by ionizing radiation, at a low dose rate, of adaptive repair response at the organism level.     

A cytogenetic study of the bone marrow cells from the 1st-generation offspring of irradiated monkeys]

Genetic structure was studied in cells of F1 posterity whose parents had survived irradiation exposure (2.2-6.6 Gy) 6-13 years ago. In juvenile monkeys (F1) aged from 1.5 to 2.5 years the frequency of aberrations exceeded reliably the spontaneous levels but was considerably lower than this in their irradiated parents. Chromosome aberration types coincided with those of the control ones. The changes revealed in the bone marrow cells of the posterity from irradiated individuals can be regarded as an intensive spontaneous mutational process.