The authors investigated morphocytochemical and immunological indices of blast cells of 81 patients with acute leukemia and 70 patients with lymphosarcoma at the stage of leukemization. Blast cells in acute leukemia were shown to have the phenotype of early hemopoietic precursors whereas in lymphosarcoma blasts were more differentiated. Morphologically in leukemia blasts were characterized by homogeneity, and in lymphosarcoma by considerable polymorphism and a higher mitotic activity.

The influence of live bacteria and antigenic preparations of virulent and avirulent stains of Shigella flexneri 2a on the endogenous splenic colony formation in murine hematopoietic cells has been studied. The different stimulating activity of live microbial cells of virulent and avirulent strains Shigella flexneri 2a and their antigenic preparations on the endogenous colony formation has been shown. The effect observed depends on the preparation doses and time of their administration before irradiation of the animals. The stimulating influence on the development of hemopoiesis endogenous foci may be conditioned by the action of heat-labile products of the live microbial cells and closely correlates with the virulence of strains studied.

Normal gastric mucosa and that in atrophic gastritis was studied by indirect immunoperoxidase method. Intestinal antigens CEA and beta 1MA were found in the foetal stomach and in the foci of intestinal metaplasia with and without dysplastic epithelial changes. Gastric antigens, pepsinogens of the foetal and 2-nd type, were found in foetal and adult stomach, as well as in the foci of intestinal metaplasia with dysplastic changes. The discovery of concomitant presence of gastric and colonic antigens in the dysplastic epithelium may indicate the existence of pluripotent stem cells capable of differentiation in the direction of gastric glandular epithelium, and in the direction of enterocytes. The possibility is suggested of origination of gastric carcinoma of different histologic structure from intestinal metaplasia with dysplastic changes.

Administration of neurotensin or its analogue into the hypothalamic structures altered the degree of activity synchronization among hypothalamic and brain-stem structures, the synchronization becoming most obvious among ventro-medial nucleus, amygdala and the central grey matter. Administration of the drugs into the 3rd ventricle and paraventricular nuclei suggested antagonistic effects of these peptides at the hypothalamic level. The data obtained could be regarded as local effects of the neuropeptides upon neurons of the paraventricular nucleus and as systemic effects upon argentaffin cells of the stomach antral portion.

The bone marrow cells of mice, rats, guinea pigs, Syrian and dwarf hamsters exhibit a positive immunofluorescence reaction with antisera against insoluble antigens of the bone marrow cells of mice, Syrian and dwarf hamsters and, hence, contain common "cross-reacting" antigens. The use of different methods of antiserum absorption made it possible to reveal, in addition, antigens of "narrow" specificity in (1) mice, Syrian and dwarf hamsters, (2) Syrian and dwarf hamsters, as well as species specific antigens of the bone marrow cells of mice, Syrian and dwarf hamsters.

The mechanism of tonic component of the frog myocardium potassium contraction was studied. The degree of contraction depended on the potassium, sodium and calcium ions concentrations in extracellular medium. The tonic component of hyperpotassium contraction, as well as the additional contractions due to hyposodium and hypercalcium medium in the tonic component phase seems to stem from activation of sodium--calcium exchange. The latter through the sarcolemma of the heart cells was 3Na: 1Ca. The effect of some mono- and bivalent cations on sodium-calcium exchange in respect ot their inhibiting activity was as follows: Cd+2 greater than Sr+2 greater than Ba+2 greater than Mn+2 much greater than Mg+2 greater than Li+ greater than Cs+.

The cloning method was used to study the content of B- and T-lymphocyte committed precursors in central and peripheral organs of the immune system of mice at different times after long-term exposure to tritium oxide (a cumulative dose of approximately 9 Gy). It was shown that recovery of the colony-forming ability of the committed lymphocyte precursors was different in central and peripheral lymphoid organs; the dynamics and degree of restoration of the pools of B--(CFU--LB) and T--(CFU--LT) lymphocyte precursors were different.

A study was made of the influence of T-cell mitogens (Con A and PHA) on the colony formation and differentiation of hemopoietic stem cells from normal and thymectomized mice, as well as of the relationship between the colony formation and the dose of injected thymocytes. The incubation of bone marrow cells with Con A and PHA was shown to inhibit the growth of spleen colonies. This inhibition is reduced by thymocytes within the dose intervals of 0.25-2.0 X 10(7) cells/mouse. Administration of these agents serially has led to the potentiation of inhibition effect and to the inability of thymocytes to reverse it. Con A and PHA exert no effect on the differentiation of stem cells. Incubation of the bone marrow cells from thymectomized mice with Con A is much less effective in the depression of colony formation, if compared with the treatment by intact bone marrow preparations. A reversed picture was observed using antiserum to mouse brain (RAMBS). It is proposed that regulation of stem cells is governed by different subpopulations of thymocytes.

Migration of FITC-labeled mouse bone marrow cells into the thymus was measured by flow cytometric analysis 3 hours after intravenous injection of cells into irradiated mice. The percentage of cells reaching the thymus diminished when the dose of injected cells increased. The dependence of the number or labeled cells in the thymus on the dose of injected cells was not linear. Pretreatment of cells with anti-SC-I serum, peanut lectin or H-2 incompatibility antigen abolished thymus migration, while treatment with anti-Thy-I serum, soybean lectin, trypsin or Thy-I-incompatibility antigen diminished cellular migration and treatment with neuraminidase enhanced it. It was concluded that the main type of migrating cells is SC-1+ precursors of T-lymphocytes. Penetration of these cells through the blood-thymus barrier is based on the recognition of their partly sialized surface glycoprotein receptors by membrane lectins of the blood-thymus barrier cells.

It has been previously demonstrated by the authors that histological characteristics of colony-forming units (CFUs) in normal mice prove a certain shift in their differentiation in erythroid direction comparing to the bone marrow CFUs. Thymectomy of mature animals is accompanied with weakening growth of granular colonies at cloning of the bone marrow CFUs and with loss of stability in direction of splenic CFUs differentiation. Polypeptide preparation of the thymus--thymalin stimulates growth of the granulocytic colonies from the splenic CFUs in thymectomized mice both in in vivo and in vitro experiments. Differentiation of the bone marrow CFUs is normalized under the effect of thymalin in in vivo experiment only. The data obtained confirm the suggestion made by R. V. Petrov on existence of T-cell clone, enhancing CFUs differentiation in granulocytic direction. Activation of this clone in the spleen is revealed at thymectomy and stimulation of the cells with thymalin both in in vivo and in vitro experiments. Thus, affirmations are obtained on differences of clonic T-cell regulation of the CFUs differentiation in the bone marrow and in the spleen.

A study was made of the survival rate of Ehrlich ascites clonogenic cells on the 7th day following inoculation depending on 60Co-gamma-radiation dose delivered under hypoxic and oxygenating conditions in vitro. In both cases the survival curves had a small shoulder and an exponential part. The oxygen enhancement ratio determined as a ratio of D0 for hypoxic (6.59 Gy) and oxygenated (2.06 Gy) cells was 3.2.

A study was made of the dependence of survival of Ehrlich ascites tumor clonogenic cells on the 3d and 7th days following inoculation upon radiation dose (60Co-gamma-rays) delivered under well oxygenated in vitro conditions. No differences were detected in radiosensitivity of 3- and 7-day Ehrlich ascites tumor cells: in both cases, the "dose-effect" curves were S-shaped with a small shoulder and close D0 values.