NASA NTRS · 20040088725
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Cucinotta, F. A., Nikjoo, H.. 2001-11-01. Preface. https://ntrs.nasa.gov/citations/20040088725
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The potential use of flavonoids as a radioprotector is of increasing interest because of their high antioxidant activity and abundance in the diet. The aim of this study is to examine genotoxic and radioprotective effects of one of the most common flavonoids, apigenin, on radiation-induced chromosome aberrations in human lymphocytes. The cytokinesis-block micronucleus (CBMN) assay was used to evaluate such effects of apigenin. Blood samples were collected from two non-smoking healthy male volunteers who had no history of previous exposure to other clastogenic agents. Isolated lymphocytes were cultured. There were two tubes per concentration for all treatments. To evaluate the genotoxicity of apigenin, cells were first treated with different concentrations of apigenin (0, 2.5, 5, 10 and 25 microg/mL) at 24 h after culture initiation, followed by cytochalasin-B (Cyt-B) treatment (3 microg/mL) and cell harvest at 44 and 72 h, respectively. Secondly, to investigate the radioprotective effect, cell cultures were exposed to different concentrations of apigenin as described above for 30 min before being irradiated to 2 Gy of 137Cs gamma rays (at a dose rate of 0.75 Gy/min). In all instances, the frequency of MN was scored in binucleated (BN) cells. The nuclear proliferation index also was calculated. We did not detect an increase in the frequency of MN in non-irradiated human lymphocyte cultures treated with 2.5, 5.0 or 10 microg/mL apigenin; although, we did observe an increase in cultures treated with 25 microg/mL apigenin (the highest concentration of apigenin used in our study). We also observed a significant increase in the frequency of MN in irradiated cells overall; however, the frequency was decreased as the concentration of apigenin increased, suggesting a radioprotective effect. These findings provide a basis for additional studies to help clarify the potential use and benefit of apigenin as a radioprotector.
To investigate effects of low dose heavy particle radiation to CNS system, we adopted mouse neonatal brain cells in culture being exposed to heavy ions by HIMAC at NIRS and NSRL at BNL. The applied dose varied from 0.05 Gy up to 2.0 Gy. The subsequent biological effects were evaluated by an induction of apoptosis and neuron survival focusing on the dependencies of the animal strains, SCID, B6, B6C3F1, C3H, used for brain cell culture, SCID was the most sensitive and C3H the least sensitive to particle radiation as evaluated by 10% apoptotic criterion. The LET dependency was compared with using SCID and B6 cells exposing to different ions (H, C, Ne, Si, Ar, and Fe). Although no detectable LET dependency was observed in the high LET (55-200 keV/micrometers) and low dose (<0.5 Gy) regions. The survivability profiles of the neurons were different in the mouse strains and ions. In this report, a result of memory and learning function to adult mice after whole-body and brain local irradiation at carbon ion and iron ion.
Two conflicting phenomena, bystander effect and adaptive response, are important in determining the biological responses at low doses of radiation and have the potential to impact the shape of the dose-response relationship. Using the Columbia University charged-particle microbeam and the highly sensitive AL cell mutagenic assay, we show here that non-irradiated cells acquire mutagenesis through direct contact with cells whose nuclei have been traversed with a single alpha particle each. Pretreatment of cells with a low dose of X-rays four hours before alpha particle irradiation significantly decreased this bystander mutagenic response. Results from the present study address some of the fundamental issues regarding both the actual target and radiation dose effect and can contribute to our current understanding in radiation risk assessment. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.