Humanized Mice as a Model to Assess the Response of Human Hematopoietic Stem Cells to Irradiation.

NOD SCID mice were humanized by transplanting human hematopoietic cells isolated from umbilical cord blood. A dose-dependent death of hematopoietic cells and their subsequent recovery were shown after acute external γ-irradiation in the model of humanized mice. The proposed approach can be used for preclinical studies of radioprotective agents and for assessment of the impact of adverse factors on the survival rate and functional properties of human hematopoietic stem cells in vivo.

Fish otoliths as biological dosimeter: internal dose calculation.

Otoliths are organs used by fish for hearing and keeping balance. They consist of biogenic crystals of hydroxyapatite and do not contain any living cells. Upon exposure to ionizing radiation, otolith hydroxyapatite accumulates radiation-induced stable CO radicals whose amount is proportional to absorbed dose.

The radiation exposure of fish in the period of the Techa river peak contamination.

Waterborne radioactive releases into the Techa River from the Mayak Production Association in Russia during 1949-1956 resulted in downstream contamination of the river ecosystem. The discharged liquid waste contained both short-lived isotopes (Zr, Nb, Ru, Ce, Y, Sr and Ba with half-life from 3 days to 1.02 years) and the long-lived Sr and Cs (half-life - 28.

Assessment of Erythropoiesis Status in Roach (Rutilus rutilus) of the Radioactively Contaminated Techa River.

At present volumetric activity of β-emitting radionuclides in water at various locations of the Techa River ranges from 5 to 40-Bq/L; a specific activity of β-emitting radionuclides in the bottom sediments at various locations ranges 10 Ito 106 Bq/kg dry weight. A significant increase of the erythroblast content in blood as compared to that in the roach from the reference watercourse (the Miass River) was observed during spawning in the spring. Due to this fact the number of erythrocytes was equal to that in the control animals under chronic radiation exposure at the dose rates of 0.

Evaluation of distribution coefficients and concentration ratios of (90)Sr and (137)Cs in the Techa River and the Miass River.

Empirical data on the behavior of radionuclides in aquatic ecosystems are needed for radioecological modeling, which is commonly used for predicting transfer of radionuclides, estimating doses, and assessing possible adverse effects on species and communities. Preliminary studies of radioecological parameters including distribution coefficients and concentration ratios, for (90)Sr and (137)Cs were not in full agreement with the default values used in the ERICA Tool and the RESRAD BIOTA codes. The unique radiation situation in the Techa River, which was contaminated by long-lived radionuclides ((90)Sr and (137)Cs) in the middle of the last century allows improved knowledge about these parameters for river systems.