[en] Erythropoietin (epo) added to liquid cutures of mouse bone marrow cells affected both the numbers of spleen colony-forming cells (CFU) in the cultures and the types of spleen colonies formed from these cells in irradiated hosts. Epo caused an increase in the numbers of CFU detected in cultures on the second day; this effect persisted through day 10, with the maximal increase occurring on the seventh day. The magnitude of the rise on day 7 was proportional to the amount of epo added. The increase in spleen colonies found with cells cultured in the presence of epo was due solely to erythroid colonies. After seven days in culture without epo, there was a peak of cells that formed non-erythyroid colonies. This peak did not appear when the cells were cultured in the presence of epo

[en] It has been found that the yield of endogenous splenic colonies and the survival of irradiated animals increase after administration of partly purified exogenous interferon to mice two days before irradiation. Incubation of the bone marrow cell suspension with the interferon decreases the yield of exogenous splenic colonies. Such an effect of the interferon seems to be related to its action of the CFU cell cycle. The level of the endogenous interferon is suggested to play an important part in the mechanism of the poly 1-poly C action on the population of cells of stem haemopoietic fraction

[en] Short note

[en] Treatment of mouse hematopoietic cells with heterologous antiserum raised against mouse brain tissue markedly reduces the capacity of pluripotent stem cells (CFU-S) to form surface spleen colonies in lethally irradiated mice. To exclude the possibility that such treatment interferes only with the capacity of CFU-S to form surface spleen colonies, we evaluated the capacity of CFU-S which were treated with rabbit anti-mouse brain serum (RAMBS) to restore hematopoiesis and rescue lethally irradiated mice, and to form microscopic spleen colonies. Marrow cells were treated with RAMBS or control rabbit serum. Fifty thousand treated nucleated cells were injected i.v. into lethally irradiated mice, and hematopoietic reconstitution was studied between days 8 and 15; separate groups of mice were observed for survival. We found that treatment with RAMBS impairs the capacity of marrow cells to repopulate the marrow and spleen with CFU-S, to restore blood RBC, to effect and overshoot in spleen weight, and to prolong survival; in addition it reduces the number of microscopic spleen colonies to the same extent that it reduces the number ot macroscopic colonies. Hence, RAMBS appears to effect a general inactivation of CFU-S and should prove to be a useful tool in further investigations of mouse hematopoiesis. (author)

[en] While intact or irradiated bone marrow cells are subjected to syngenic transplantation, 2 to 3 times more macrocolonies are observed as compared to microcolonies. The number of macro- and microscopically detected colonies is a linear function of the number of drafted cells and an exponential function of irradiation dose. The relative amount and radiosensitivity of bone narrow cells that form colonies of erythroid, myeloid and metakaryocytic types were somewhat different

No abstract available

[en] A yield of endogenous splenic colonies was studied as function of radiation doses in intact and irradiated (3 days before a test exposure of 400 R) mice. It was established that in preirradiated moce, D₀ for endogenous CFU is 119+-13.3 R, as opposed to 73.9+-4.7 R in intact animals

[en] Short note

[en] A priming irradiation with 0.45 Gy of X-rays, given 2 weeks prior to the challenging exposures, induces radio-resistance (decrease in bone marrow death rate after mid-lethal irradiations) in mice of C57BL/6 mice. This acquired radio-resistance appeared on day 9 and continued till day 17 after the priming irradiation, with a maximal on days 12-14 and diminished on day 21. The priming irradiation, given 14 days prior to the challenging exposure, increased endogenous spleen colonies on days 12-13 after exposure to 5.0 Gy. Effect of interval time between the priming and the challenging irradiations on the increase in endogenous spleen colonies was also examined. Significant increase of the colonies by the priming irradiation was observed when the interval time was 12-17 and 21 days. The results correspond to the increase of the survival rates on days 12-17 after the challenging irradiations. (author)

[en] The expanding usage of radiation and radioisotopes in industry, medicine, and scientific research operations has entailed the necessity of efficient radioprotectors to reduce the biological damage during medical usage or after accidental exposure. Natural products such as herbal medicines, which are relatively less toxic, have recently begun to receive some attention as possible modifiers for radiation response. Taraxaci Herba (the aerial part of Taraxacum mongolicum, Compositae family) is a medicinal herb which has been traditionally used in Eastern Asia. In this study, we have evaluated the antioxidant and radioprotective activity of hot water extract of Traxaci Herba (TH extract) in vitro and in vivo models