[Study of the dynamics of endogenous IL-6 in the culture erythroblastic islands].

It is found that in the process of cultivating the erythroblastic islets (EI) of rat bone marrow, the concentration of interleukin-6 (IL-6) increases in the culture medium. Stimulating erythropoiesis was observed on the 48th hour in cultures, the stimulation was characterized by the growth of endogenous erythropoietin and activation of formation of EI de novo and de repeto. The continuing increase in the concentration of IL-6 in the cultures at the 72nd hour of the experiment was accompanied by a decrease formation of islands de novo and a decrease in the absolute number of EI in culture.

[Effect of supernatant of erythroblastic island bone marrow cultures on erythropoiesis in vitro].

It was shown that joint cultivation of supernatants with bone marrow erythroblastic islands in liquid culture systems resulted in stimulatory or inhibitory effects on erythropoiesis. Influence of supernatants on erythropoiesis depended on the culture age, erythrocyte production in these cultures and duration of joint cultivation with bone marrow islands. Supernatants of 24 h cultures induced formation of erythroblastic islands de repeto and de novo in cultures. Supernatants of 48 h cultures caused stimulation of erythropoiesis (to the end of 24 h period ofjoint cultivation) and processes of maturation in erythroblastic islands (at the 48th of joint cultivation). Supernatants of 72 h cultures inhibited formation of erythroblastic islands de novo and de repeto, but stimulated the processes of their maturation.

[Dynamic changes of erythropoietin and tumor necrosis factor-alpha levels in peripheral blood and their correlation with erythropoiesis changes in posttransfusion polycythemia in animals].

Posttransfusion polyglobulia reveals elevated level of the tumor necrosis factor-alpha in peripheral blood, suppresses erythropoiesis in bone marrow erythroblastic islands by diminishing the newly forming erythroblastic islands, and suppresses erythropoietin production in rats.

[The investigation of dynamic changes of erythropoietin content of the erythroblast island cultures].

Dynamic changes of erythropoietin content on the 6th, 12th, 24 and 48th hours of cultivation in bone marrow erythropoietic island liquid short-term cultures were investigated. The initial doses of 0.25, 0.5, 1 mE/ml oferythropoietin was used, and one series with no erythropoietin as control. In culture with 0.25 mE/ml of erythropoietin, its reduction was registered from the 6th to 48th hours of cultivation with relatively lower number of erythroblast islands in state of involution, and a higher number in the state of reconstruction. In cultures with 0.5 mE/ml oferythropoietin, the same erythropoietin reduction was registered with relatively higher numbers of erythroblast islands in the state of reconstruction, and with an unexpected elevation of erythropoietin concentration on the 48th hour of cultivation. In cultures with 1 mE/ml oferythropoietin, such unexpected rise in erythropoietin content was registered in 24 hours, accompanied by relatively higher number of erythroblast islands in the state of reconstruction.

[The effect of various stage maturity of erythrocytes upon proliferatio rate of erythroid cells in "crown" of erythroblastic islands]. / Vliianie éritrotsitov raznoi stepeni zrelosti na proliferativnuiu aktivnost' éritrotroidnykh kletok "korony" éritroblasticheskikh ostrovkov.

Joint cultivation of small amounts of young and mature erythrocytes with bone marrow erythroblastic islands during 24 hours in liquid culture system results in erythropoiesis stimulation due to increase of number of cells in the state of mitosis in island's "crown". Prolonged joint cultivation and/or joint cultivation with plenty of premature and mature erythrocytes leads to inhibition of the erythropoiesis in the state of mitosis in the island's "crown". The maximum of the inhibitory effect was shown by erythrocytes from polycythemia rats.

[Effect of erythrocytes from intact, polycythemic, and anemic rats on erythropoiesis in erythroblastic island culture]. / Vliianie éritrotsitov intaktnykh, politsitemichnykh i anemizirovannykh krys na éritropoéz v kul'ture éritroblastichnykh ostrovkov.

Comparison of influence of erythrocytes of different stages of maturity, and their amount on erythropoiesis in erythroblastic island culture revealed their dose-dependent and maturity-dependent inhibiting effect on erythropoiesis. Erythrocytes of polycythemic rats inhibit maturing and formation of erythroblastic islands more intensively than erythrocytes of normal on anemic rats.

[Activity of the nucleolar organizers in cultured cells from the bone marrow erythroblastic islets]. / Aktivnost' iadryshkovykh organizatorov v kletkakh kul'tur éritroblasticheskikh ostrovkov kostnogo mozga.

The erythroblast islands of the bone marrow are the morphofunctional units of erythropoiesis. In this work, the functional state of erythroblast islands' cells of the bone marrow for the first time was defined by estimation of the activity of the nucleolar organizers of erythroid cells in the erythroblast islands cultivated during 24 and 48 hours in presence of various doses of erythropoietin. The findings indicated that an increase in doses of erythropoietin was accompanied by a corresponding increase of the activity of nucleolar organizers in erythrokaryocytes of erythroblast islands. The nucleolar organizers of erythroid cells in cultures of erythroblast islands responded with activation to very small doses of erythropoietin; besides, a proliferative response of erythrokaryocytes was observed after activation of the nucleolar organizers.

[The effect of humoral factors on phagocytic activity of central macrophages in the erythroblast islet culture]. / Vliianie gumoral'nykh faktorov na fagotsitarnuiu aktivnost' tsentral'nykh makrofagov v kul'ture éritroblasticheskikh ostrovkov.

A 24-hour cultivation of erythroblast islets (El) in presence of erythropoietin (EP) and macrophage colony stimulating factor (MCSF) led to a concentration-dependent enhancement of phagocytic activity (PA) of the El's "central" macrophages. The latter phenomenon was revealed in "mature" El classes only. The PA of "central" macrophages in "proliferating" El appeared to be affected neither by EP, nor by MCSF.

[Activity of nucleolar organizers in the cells of erythroblastic islands in the bone marrow in various erythropoietic functional states]. / Aktivnost' iadryshkovykh organizatorov v kletkakh éritroblasticheskikh ostrovkov kostnogo mozga pri razlichnykh funktsionanl'nykh sostoianiiakh éritropoéza.

Erythroblastic islands (EIs) of the bone marrow are the morpho-functional units of the erythron. The functional state of the cells of EIs of varying maturity was first studied by estimating the activity of nucleolar organizers in intact rats and in rats with acute blood loss or posttransfusion polycythemia by the modified method of J. Croker and P. Nar. The intact rats had the largest number of nucleoli and intranuclear argentum inclusions located within and outside the nucleoli in EIs of proliferating classes: Class 1 EIs and reconstructing EIs and the smallest number in involutional EIs. Blood loss was accompanied by the enhanced activity of nucleolar organizers in EI cells. In polycythemia, the activity of the organizers changed in a more complicated manner.