Recurrent inhibition was studied by antidromic stimulation of Renshaw's cells. 25 normal subjects and 74 patients with CNS lesions accompanied by movement disturbances were examined. During weak voluntary contraction of the soleus muscle, the stimuli were applied to motor fibers of the n. tibialis (weak M-response was evoked). In normal subjects, the stimulation was followed by short-latency suppression of the EMG background activity of the muscle brought about by recurrent inhibition. The same inhibition was revealed in patients with spastic paresis caused by pyramidal system lesion. However, the stimulation failed to evoke the recurrent inhibition in patients with movement disturbances caused by brain stem and cerebellum lesions, including patients with hypotonia.

Altogether 67 patients with chronic glomerulonephritis (CGN) were examined for the content of thymus-dependent precursor lymphocytes (auto-RFC, pre-T-cells). The patients suffering from CGN were characterized by the high content of the young post-thymic T-cells (auto-RFC) and high affinity T lymphocytes carrying a receptor for the Fc fragment of IgM as compared to normal donors. In patients with different clinical patterns of CGN, an analysis was made of the content of precursor thymus-dependent lymphocytes. A relationship was discovered between the content of pre-T-cells and the activity of the nephritic process. The activity of the pathological process was associated with the high content of precursor lymphocytes. The inactive course of nephritis was characterized by a well-defined reduction of the number of precursor cells. This might be regarded as depletion of the amount of precursor lymphocytes.

The effects of thymic peptide (thymalin), bone marrow peptide (haemalin) and a complex compound (thymohaemin) on the haematopoiesis and immunity were studied in the experimental model of the induced haematopoiesis depression. Lymphopoiesis stimulation in the bone marrow was provoked by thymalin and granulopoiesis stimulation by haemalin. Simultaneously the restoration of a number of both T- and B-lymphocytes in the thymus was observed. Thymohaemin resulted in the restoration of practically all peripheral blood and bone marrow indexes as well as content of T- and B-lymphocytes in both central and peripheral immunogenetic organs. Likewise the use of the thymus and bone marrow peptide preparations facilitated the restoration of non-specific resistance which was evaluated by means of an integral index--lysosomal cation test. The results allow us to recommend the above preparations for a clinical trial in the haematopoiesis depletion.

The lipoxin B (5, 14, 15-trihydroxy-6, 8, 10, 12-eicosatetraenoate) obtained by the enzymatic peroxidation of 5, 15-dihydroxy-6, 8, 11, 13-eicosatetraenoate (5, 15-DHETE) with the homogenous rabbit reticulocytes lipoxygenase and purified by HPLC stimulates the proliferation and differentiation of granulocyte-monocyte colony formation units (CFU-GMdc) of human peripheral blood at 3.6 X 10(-9) 3.6 X 10(-8)M in diffusion chamber placed in mouse abdominal cavity. The lipoxin B precursors namely 5,15-DHETE and arachidonic acid had stimulating influence at about 10(-6) and 10(-3)M respectively. The formation of polynuclear cells under the action of the studied lipoxygenase metabolites of the arachidonic acid was shown.

Three types of spermatogonia have been distinguished in the fur seal: type A, intermediate, type B. The type A spermatogonia are presented by means of five varieties: stem A, A1, A2, A3, A4. The spermatogonia of the stem A type is characterized with presence of equally distributed chromatin in the nucleus. The spermatogonia of the A1-A4 types are characterized with a gradual condensation of chromatin. The intermediate spermatogonia possesses a light nucleus, chromatin as small and large granules is situated near the nuclear membrane. The spermatogonia of B1-B3 types have a round nucleus, their chromatin is granular. Spermatocytes both at the leptotene stage and at the zygotene stage are presented by means of three cellular forms. At the pachytene stage four cellular forms are distinguished. Basing on formation of the acrosomic apparatus, 18 stages of spermatids development are distinguished.

In the presence of irradiated bone marrow cells the efficiency of stromal colony formation increases from 0.8 +/- 0.2 to 3.6 +/- 0.4 per 10(4) explanted bone marrow cells. The growth-stimulating activity of bone marrow cells on passaged bone marrow fibroblasts depends on growth conditions of passages to which irradiated bone marrow cells are added. The response of proliferating bone marrow fibroblasts to stimulating activity of bone marrow cells is low, while addition of bone marrow cells to fibroblast cultures stimulates their proliferation.

During serial passages of hemopoietic tissue as a whole ectopic hemopoietic site under renal capsule of irradiated mice gradual decrease of proliferative potential of CFUs has been observed. The results suggest that the most probable cause of such decline is random loss of precursor cells with high but limited proliferative potential during serial passages of hemopoietic tissue.

A prolonged self-maintenance of haemopoietic tissue cells with stable chromosome rearrangements following a single intake of tritium oxide in the amount of 24 MBq/g of body weight (absorbed dose of 11 Gy) is shown. Mutant cells revealed long after the radionuclide exposure are descendants of stem-cell precursors, bearing stable chromosome aberrations during the period of formation of radiation injury after the radionuclide administration.

The data on histological and electron microscopical investigation of the endosteal cells of the human iliac bone are presented. Three types of stromal elements in the endosteum, differing in their ultrastructural organization have been revealed. In the endosteal areas young hemopoietic cells are present, they are closely connected with the stroma. A suggestion is made on an important role of the endosteum in processes of proliferation and differentiation of hemopoietic predecessors.

Dynamics of the numbers of population of proliferating cells under periodic phase-specific cytotoxic effect with and without blocking action was studied on the basis of a mathematical model. It has been shown that at real values of the model parameters after the beginning of the effects the population number exponentially depends of time. Dependence of the population number dynamics on integral parameters of the cell cycle and the exposure regime was studied. It has been shown that at certain periods a resonance decrease of the damage of the population cells must be observed. The values of the periods corresponding to the resonance decrease of the damage are determined mainly by the mean duration of the cell cycle and the time of blocking action, at small duration of the blocking action they are approximately multiple to the average time of the cell cycle. The theoretical predictions are proved experimentally in the experiments on determining the relationship between the damage of small intestine epithelium and mouse survival and the period of repeated periodic injections of S-phase-specific cytotoxic agent hydroxyurea. A distinct resonance increase of mouse survival and decreased damage of the epithelium were observed under the injections of oxyurea with the periods near to the mean and doubled mean time of the cell cycle of crypt enterocytes. The results obtained not only support the correctness of theoretical predictions, but make it possible to estimate the parameters of the stem cell cycle of mouse small intestine epithelium. They also show that this approach can be used for reducing aftereffects of chemotherapy by means of phase-specific agents.

The value and radiosensitivity of human haemopoietic stem pool may be assessed by the number of colonies of nondifferentiated cells (CFUnc) formed in situ during regeneration of the haemopoietic organ from the postirradiation aplasia. The time required for doubling the population, that constitutes nondifferentiated cell endocolonies, was reduced as the radiation dose increased.

Survival of clonogenic cells of solid Ehrlich ascites tumor (EAT) exposed to 60Co-gamma-radiation in vitro under the oxygenation conditions was investigated and the clonogenic capacity and radiosensitivity of these cells and cells of the previously studied EAT ascitic form and Lewis solid tumor comparatively studied to elucidate how the efficiency of colony formation (ECF) would affect their radiosensitivity. ECF for solid EAT cells was 2.6 +/- 0.3%, which was lower, by about an order of magnitude, than that for ascitic form of this tumor and was nearly the same as that for Lewis tumor cells. A median cell lethal dose (D0) was practically the same for all tumors under study. It is suggested that the differences in ECF do not substantially influence the radiosensitivity of clonogenic cells of the studied tumors.

Expression of the inactivation effect of the stem colony-forming marrow cells of male mice CBA, C57B1/6, (CBA.C57B1/6)F1 and (C57B1/6.CBA)F1 by syngeneic lymphocytes of lymphatic nodes of females in conditions of transplantation of cell mixtures into lethally irradiated recipients was studied. The maximum inactivation effect of stem cells (86.3%) is determined in mice F1 with differences of H-Y antigen, the minimum effect (2.4%)--in mice CBA, an intermediate effect (54%) being registered in mice C57B1/6. Sensibility of target cells to the inactivation influence of lymphocytes distinguished by weak transplantation H-Y antigen depended on the maternal effect and direction of reaction. The inactivation effect was maximal in the combination CBA----C57B1/6 and C57B1/6----C57B1/6, as compared with the combination CBA----CBA and C57B1/6----CBA. Possible mechanisms by which the killer action of syngeneic lymphocytes on the antigen H-Y of target cells is developed differently, are under discussion.

The rabbit anti-mouse brain serum (RAMBS) that interacts with SC-1 marked cells, rather than with thymocytes and bone marrow cells, inhibits most of the blood and bone marrow colony-forming unit (CFU) population. A commercial thymus preparation thymalin increases the granulocytopoietic activity of the circulating CFU and decreases their sensitivity to RAMBS in thymectomized and normal animals. Differentiation of circulating CFU remains unchanged in thymalin-treated mice after RAMBS administration, while CFU erythroid activity of nontreated animals is lowered. The revealed changes in the CFU differentiation and sensitivity to RAMBS confirm the assumption that SC-1 antigen may mark Thy-1 lymphocytes of their microenvironment, rather than CFU.

Monoclonal antibodies (Mab) ICO-13 of IgM isotype reacted in indirect surface immunofluorescence test with 88.5 +/- 3.4% of thymocytes and 7.1 +/- 2.4% of T cells, but failed to react with other peripheral blood cells from healthy donors. The antigen disappeared in cells stored at 4 degrees C overnight or at -196 degrees C in liquid nitrogen. The antigen detected by Mab ICO-13 was expressed on blast cells of acute lymphoblast leukemias and lymphomas. The antigen was absent in chronic lymphoblast leukemia and blast crisis of chronic myeloid leukemia.