Conditions have been developed for cloning cells-precursors of rat bone marrow haemopoietic stroma, that form in culture dense and sparse fibroblast colonies (CFU-F) at a plating efficiency of 10(-4). Radiosensitivity of rat bone marrow CFU-F, with 60Co-gamma-irradiation in vitro, is characterized by the values of Do and n of 1.87 Gy and 1.4 respectively for all clones; 0.65 Gy and 6.7 for dense clones, and 4.27 Gy and 1.0 for sparse clones. This confirms the observed heterogeneity of CFU-F population consisting of highly radiosensitive and radioresistant subpopulations. The parameters of rat bone marrow CFU-F are nearly the same with irradiation both in vivo and in vitro; with in situ irradiation, the oxygen effect comes into play in a radiosensitive subpopulation of CFU-F; the OER values are 1.6, 2.6 and 0.9 for all, dense and sparse clones respectively.

A comparison was made of the biological effect on mice of irradiation at different dose rates (70, 5.5 and 1.5 cGy/min) with equally effective, with respect to lethality, doses, or with physically equal doses within the range from 1/4 of LD50/30 to LD99-95/30. Equally effective, with respect to lethality, doses caused similar changes in the intestinal epithelium and in the haemopoietic system. The death rate kinetics was identical with doses of LD80-95/30 within the dose-rate range under study. The equally effective doses caused injuries, different in degrees, to critical systems, including CFUs.

Peripheral blood and bone marrow morphology, blood and bone marrow lymphocyte subpopulation composition were studied in two children with cyclic neutropenia, using flow cytofluorometry, monoclonal antibodies, colony-forming capacity of granulocytic macrophagal precursors in semi-fluid agar. The studies were conducted in varying periods of the neutropenic cycle. Differences were revealed in immunohematologic parameters and clinical course of neutropenia in the two patients. The analysis of the literature data and the authors' own observations of the patients with cyclic neutropenia permitted a suggestion on high heterogeneity of pathogenetic mechanisms of this disease.

Guinea pig and rabbit bone marrow and splenic cells with increasing cellular density suppress in vitro formation of fibroblast colonies by rabbit bone marrow clonogenic stromal cells. At the same time guinea pig bone marrow and splenic cells produce a stimulating effect on guinea pig bone marrow CFUf, but they are inhibited by rabbit splenocytes, although to a lesser extent than rabbit bone marrow CFUf. Rabbit blood platelets stimulate the growth of bone marrow CFUf of these animals. However, introduction into the culture of rabbit bone marrow cells combined with platelets eliminates the latter's growth-stimulating effect on stromal clonogenic cells of rabbit bone marrow. The results obtained have evidenced that guinea pig and rabbit bone marrow and lymphoid cell populations contain cells both stimulating and inhibiting CFUf proliferation, and that CFUf of varying animal species have different sensitivity to growth-stimulating and growth-inhibiting effects.

The investigation of effective and ineffective erythropoiesis in long-term hemorrhages has shown that the index of normal erythroblasts maturation is decreased down to 0.7 +/- 0.01 (P < 0.01) that evidences disorders in the process of proliferation and differentiation of the erythron cells. A rise of ineffective erythropoiesis was observed at the level of polychromatophilic normal erythroblasts , the mean number of PAS (positive cells) comprised 22.9 +/- 4.1% (P < 0.05). Erythropoiesis intensity was lowered and erythrocyte life was shortened. The data obtained are important for the evaluation of the erythron system lesion and purposeful therapy.

A cytogenetic examination of a cow and its offsprings, obtained by pair transplantations of the embryos was carried out. The fragile X and the heteromorphism of the chromosomes XX of this cow and some of its offsprings were revealed. The variability of the hematological chimerism of the pair transplanted embryos was observed. The immigrated cells were, as a rule, distinguished by the comparatively low frequencies of the metaphases with the nearly located chromosomes XX. The heterogeneity of the stem blood cells of the embryos for some traits, and for the ability to migrate in the blood of the twin is under discussion.

It has been shown that hypoosmotic autoblood injected sub- or intracutaneously stimulates the colony-forming activity of haemopoietic stem cells in mice. Autoblood injected to animals immediately after their irradiation stimulates haemopoiesis even after a single dose. When mice are injected with autoblood prior to irradiation, the time between the first injection and the day of irradiation is critical for manifestation of the immunomodulating effect. Autoblood infusions immediately before, the day before, or two days before irradiation markedly deteriorate the clinical status of experimental animals and cause death in some of them. It is suggested that stimulation of haemopoiesis is associated with the appearance in the blood stream of a population of radiosensitive cells, apparently T-cell precursors.

Carnosine given to adult animals together with potable water one day prior to gamma-irradiation or injected in a single intraperitoneal dose one hour after irradiation enhances colony formation by haemopoietic stem cells migrating from the bone marrow to the spleen. In young animals with a high colony-forming activity carnosine either decreases or does not influence at all the efficiency of colony production.

A comparative study was made on the survival rate of cell-precursors of haemopoietic stroma, that form, in a rat bone marrow culture, colonies (clones) of fibroblasts (CFU-F) after gamma-irradiation of animals in the air or in a gas hypoxic mixture, containing 8% of O2 (GHM-8). Irradiation in GHM-8 was shown to increase the survival rate of CFU-F by 1.7 times (as compared to exposure in the air) as estimated by the total number of colonies that are formed in a culture; the radioprotective effect of GHM-8 was more pronounced for CFU-F which form dense colonies: DMF for dense and loose clones was 2.4 and 1.6 respectively.

In experiments with mice and dogs irradiated with LD50, it was shown the postirradiation depopulation of haemopoietic polypotent (CFUs) cell-precursors in mouse bone marrow was more pronounced than that of granulocytic and macrophagal cells (CFUdc). The rate of repopulation of CFUs during the first week was higher than that of CFUdc (T1/2 was 2.5 and 8.8 days respectively). In dogs, one could notice a partial change in the colony formation, a prolonged plateau period in the postirradiation CFUdc dynamics, and a coincidence in time with cellularity restoration in the bone marrow and peripheral blood leukocytes. It is suggested that in conditions of heterogeneous incubation in diffuse chambers, the haemopoietic cell-precursors are more mature than in the syngeneic system. The method of CFUdc determination has proved to be ineffective in estimating the onset and intensity of the postirradiation haemopoiesis recovery in dogs. The study of the bone marrow CFUdc population may, however, be used in intact animals to predict the probability of their death after irradiation within the median lethal dose range.

Proliferative potential of CFUs in bone marrow of young and adult mice (1.5-25 months) and thymus influence on this property were studied. It has been shown on the model of adult thymectomized mice that during "steady state" hematopoiesis, proliferative potential of bone marrow CFUs does not depend on the animals age and on thymic factors.

Radioprotective capacity of bone marrow CFUs of adult thymectomized mice was studied. Lethally irradiated mice were inoculated with bone marrow of mice thymectomized 8-11 months before. The colony forming capacity and proliferative rate of CFUs were studied 1-7.5 months after obtaining the radiation chimeras. It has been shown that proliferative capacity of bone marrow of adult thymectomized mice was reduced in comparison with that of normal animals. It is related to the decrease (4-fold) of the proliferative rate of bone marrow of thymectomized mice which was inoculated into lethally irradiated recipients 1 month before. We also found that the content of CFUs in bone of those chimeras was reduced later--after 7.5 months. In this period (1-7.5 months) the cellularity of bone marrow did not change.

Injection of dextran sulphate before irradiation was shown to protect jejunal epithelium stem cells (D0 increased from 1.13 to 1.82 Gy). The protective effect of a combination of dextran sulphate and gas hypoxic mixture (10% O2) did not exceed that of the administration of the gas hypoxic mixture (10% O2) alone.

A study was made of the content and morphology of haemopoietic islands in the bone marrow of lethally irradiated CBA mice, and their change after transplantation of syngeneic haemopoietic cells. The data obtained show that the haemopoietic islands are reconstructed in the injured haemopoietic tissue due to the donor's bone-marrow nuclears. A new type of structural and functional associations, namely, stromal haemopoietic islands, has been found.

The ability of transplantable hemopoietic stem cells (HSC) to maintain their pool was studied using successive bone marrow transplantations with quantitative evaluation of hemopoiesis restoring units (HRU) in each transfer. The number of injected HRU increased (3.6-48.6--fold) upon each transfer; however, the normal level could not be attained. The ability fo HRU for further multiplication was exhausted after five transfers. HRU lost totipotentiality after four transfers. The data obtained support the concertion of Kay (1965) that HSC department is a pool of heterogeneous cells, and the property of "stemness" is inversely related to the number of divisions of ancestral cells. Transplantation, being a proliferative stress for the dormant HSCs, thus lowers the stem potential of the whole pool. The experimental data suggest that while dividing stem cell does not have a choice to self-renew or to differentiate into maturing cells, but it really differentiates into HSCs of lower rank.

The review contains the present-day evidence on neurophysiological and neurochemical mechanisms of functioning the central components of vomiting reflex. The main attention is concentrated on the role of some brain structures in motion sickness-induced vomiting. At the same time, the literature data casting doubt on traditional view of a necessary involvement of some brain structures in the genesis of vomiting induced by motion sickness are discussed. Also there are findings of studying an effect of physiologically active substances (classical neuromediators and regulatory peptides) at a neuronal level (silent postremal cells) with the presence of an emetic effect in them during systemic administration. The current concept of vomiting center to which role the parvicellular reticular formation of brain stem can pretend is under study.

The data are summarized on comparative investigations by the author and co-workers concerning regenerative process in hemopoietic and connective tissues of representatives of molluscs, cyclostomes, fishes and mammals. In gastropods, a regeneration stimulus strikingly increases the volume of amebocyte reproduction foci in the pericardium (primitive organ of hemopoiesis), accelerates the amebocyte yield into the peripheral blood and induces the appearance of DNA-synthesizing cells in the latter. The stimulation of precursor cell reproduction in hemopoietic organs and the acceleration of their maturation and yield into the peripheral blood are common processes in the regeneration response for hemopoietic systems of mammals, fishes and cyclostomes. In contrast to fishes and cyclostomes, adult mammals show the absence of dividing (DNA-synthesizing) cells and mature segmentonuclear granulocytes demonstrate neither RNA nor protein synthesis. In all forms studied, the stromal type cells of hemopoietic nature (fibroblast-like, fixed macrophages, etc.) are a constant and continuously renewed component of connective tissue and play a considerable role in its regeneration.

The method of "macro-" and "microcolonies" was used to study the radiosensitivity of CFU-S that form "early" (8 days) and "late" (12 days) splenic colonies after transplantation of syngeneic bone marrow to fatally exposed mice: no significant differences were found. Median lethal doses (D0) for CFU-S-8 and CFU-S-12 were 1.03 and 1.13 Gy for "microtest" and 0.99 and 1.16 Gy for "microtest" respectively.

We studied the condition of CBA mice bone marrow hemopoiesis and functional activity of adherent cells 6 months after a single treatment with vinblastine (VB), doxorubicin (DR) and cyclophosphamide (CP) in LD10 dose (6, 22 and 250 mg/kg, respectively). There was a long-term disorganization of bone marrow cell composition. The damage may be attributed to exhaustion of the pools of stem cells and changes in function of the cells formed by hemopoiesis induction microenvironment.