| Nuclear war or radiation accidents may cause many victims with serious damages in a short time, which demands simple, reliable and rapid tests to provide biodosimetry for effective therapy. Up to date, chromosomal aberration (CA) analysis is often performed to estimate biological dose of radiation. CA analysis is reliable and reproducible and can provide the most detailed information. However, CA is time-consuming (2-3 days) and labor-intensive (manual microscopy inspection), and moreover, it needs culture of lymphocytes. Due to inhibition of cell proliferation, culture of lymphocytes becomes difficult. Therefore, CA analysis is not suitable for estimating biological dose of radiation under such conditions.Recently, many investigators consider that micronucleus (MN) is perhaps a promising biomarker for radiation. Many investigations showed that micronucleus test (MNT) is as sensitive and specific as CA analysis, however, the former is more simple and rapid, and its advantages become more prominent as automated MNT develops. In 1992, Grawe set up an automated MNT for mouse peripheral blood based on a dual-laser flow cytometer, and Cao.J in our laboratory further modified and developed it in 1993, making it suitable for practical use. However, its application on human biomonitoring was limited due to the extinction of micronucleated erythrocytes in peripheral blood by human spleen. Though great progress was also made in automated CB-MNT of human peripheral blood, a relative long time for culture of lymphocytes makes it unsuitable for estimation of biodosimetry of many victims with serious damages in a short time Based on the automated MNT for MN-Ret from mouse peripheral blood, this study attempted to set up an automated MNT for MN-Trf-Ret from human peripheral blood, with which, rapid and accurate estimation of biodosimetry can be achieved when many victims with serious damages are caused in nuclear war or radiation accidents in a short time. For such purposes, this study included three parts: in the first part, nasopharyngeal cancer (NPC) patients were selected as radiation-wounded models and their frequencies of binucleated lymphocytes (fMN-BNLs)were detected after accepting different accumulative radiotherapy dose by cytokinesis-block micronucleus test (CB-MNT) to investigate therelationship between fMN-BNLs and radiation dose; in the second part, Cyclophosphamide (CP) was used as a positive control test compound and micronucleated cells in bone marrow of CP-treated rats were assessed by a single-laser flow cytometry and microscopic inspection, attempting to set up an automated scoring system for MN based on a single-laser flow cytometry; in the third part, the automated scoring system set up in the second part was further modified and an up-to-date technique — magnetic cell isolation technique — was taken over to detect the frequencies of CD71 (also known as transferrin receptor) positive micronucleated reticulocytes (fMN-Trf-Ret) from peripheral blood of radiation-wounded models — NPC patients. The main results are presented as follows:1. Results of human peripheral blood CB-MNT: The fMN-BNLs of NPC patients were elevated rapidly and significantly after radiotherapy at different cumulative dose compared with those before radiotherapy. As the cumulative doses increased from 0Gy to 50Gy, the mean frequencies of MN-BNLs were elevated from 12.9±4.2‰ to 141±20.1‰, showing good dose-response relationship. Curve estimation by SPSS11.0 showed the regression equation is: Y=12.3458 + 10.6107X - 0.3095X2+ 0.0030X3(R=0.889, P＜0.01), confirmimg that the frequency of MN-BNLs is a good biodosimeter for radation. 2. Flow cytometric determination of MNPCE and MNNCE in bone marrow: Contour configuration histograms of FL1 (indicating DNA fluorescence) vs. FSC (indicating cell size) were used as they could provide better discrimination of low frequency events. TNC, PCE, and NCE populations were clearly evident. Use of this configuration showed a decrease in TNC density, increase in density of PCE...
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