Absorbed Dose Assessment by Quantification of Micronuclei in Blood Lymphocytes from Patients Exposed to Gamma Radiation (original) (raw)
Related papers
Genetics and Molecular Biology, 2005
Scoring of unstable chromosome aberrations (dicentrics, rings and fragments) and micronuclei in circulating lymphocytes are the most extensively studied biological means for estimating individual exposure to ionizing radiation (IR), which can be used as complementary methods to physical dosimetry or when the latter cannot be performed. In this work, the quantification of the frequencies of chromosome aberrations and micronuclei were carried out based on cytogenetic analyses of peripheral blood samples from 5 patients with cervical uterine cancer following radiotherapy in order to evaluate the absorbed dose as a result of partial-body exposure to 60 Co source. Blood samples were collected from each patient in three phases of the treatment: before irradiation, 24 h after receiving 0.08 Gy and 1.8 Gy, respectively. The results presented in this report emphasize biological dosimetry, employing the quantification of chromosome aberrations and micronuclei in lymphocytes from peripheral blood, as an important methodology of dose assessment for either whole or partial-body exposure to IR.
The scoring of micronuclei in human peripheral blood lymphocytes is used as a biomarker and dosimeter of radiation exposure. In this paper we investigated a dose response curve for micronuclei in human lymphocytes following Cs-137 irradiation in vitro. The lymphocytes were obtained from 7 different donors aged between 24 and 51 years. The applied doses were: 0.0, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0 and 4.0 Gy. There was an increase of micronuclei frequency MN with the dose. The dose-effect relationship was expressed with the following linear-quadratic equation Y = 20,56 + 39,59.D + 17,01.D 2 , where (Y)-represents the micronuclei yield, (D)-represents the applied radiation dose. A software program for absorbed dose assessment based on this equation was created.
REVIEW The micronucleus assay as a biological dosimeter of in vivo ionising radiation exposure
2010
Biological dosimetry, based on the analysis of micronuclei (MN) in the cytokinesis-block micronucleus (CBMN) assay can be used as an alternative method for scoring dicentric chromosomes in the field of radiation protection. Biological dosimetry or Biodosimetry, is mainly performed, in addition to physical dosimetry, with the aim of individual dose assessment. Many studies have shown that the number of radiation-induced MN is strongly correlated with dose and quality of radiation. The CBMN assay has become, in the last years, a thoroughly validated and standardised technique to evaluate in vivo radiation exposure of occupational, medical and accidentally ex-posed individuals. Compared to the gold standard, the dicentric assay, the CBMN assay has the important advantage of allowing economical, easy and quick analysis.
Persistence of Micronuclei in Lymphocytes of Cancer Patients after Radiotherapy
Radiation Research, 2002
To verify the applicability of the micronucleus (MN) yield in peripheral blood lymphocytes (PBLs) as a quantitative biodosimeter for monitoring in vivo ionizing radiation damage, we applied the cytokinesis-blocked micronucleus assay in PBLs of cancer patients treated with partial-body radiotherapy. Dosimetric information on these 13 patients represented a wide range in the number of fractions, cumulative tumor dose, total integral dose, and equivalent total-body absorbed dose. We found in PBLs of these patients that (1) the MN yield increased linearly with the equivalent total-body absorbed dose (r ؍ 0.8, P ؍ 0.002), (2) the distributions of the MN yields deviated significantly from Poisson, and (3) there was a general decline in MN yields with increasing length of follow-up, but with considerable variation between individuals. The average rate of decline was found to be linear and was correlated with the equivalent total-body absorbed dose (r ؍ 0.7, P ؍ 0.007). Further, at 19-75 months of follow-up time, seven patients showed higher MN yields than their respective levels before radiotherapy, indicating the persistence of radiation-induced residual cytogenetic damage. Our findings suggest that the MN yield in human PBLs offers a reliable acute and perhaps chronic biodosimeter for in vivo radiation dose estimation. After the completion of radiotherapy, the persistence of elevated MN yield in PBLs is a reflection of the surviving population of radiation-induced genetically aberrant cells.
Radiation Oncology Investigations, 1993
We obtained peripheral lymphocytes from both healthy donors (n = 7) and cancer patients (n = 14) for the cytokinesis-blocked micronucleus (MN) assay. Lymphocytes were irradiated with 13'Cs to 2 Gy. Cytochalasin B (6 &ml) was added to the incubation at 44 hr and the cells were harvested a t 72 hr. We found that compared to healthy donors, lymphocytes of cancer patients revealed no significant difference in the MN baseline level (P = 0.86). Apparently DNA damage manifested as MN in the lymphocytes of cancer patients is not more severe than that of healthy donors. In addition, 2 Gy in vitro irradiation of lymphocytes caused no difference in the MN formation between cancer patients and healthy donors (P = 0.9). Radiation induced cell cycle delay as evaluated by the number of mononucleate, binucleate, and cells with >2 nuclei and by the mitotic indices showed similar results in both populations. However, the difference for MN frequency in lymphocytes before and after 2 Gy in vitro irradiation was highly significant for both cancer patients and healthy donors (P = 0.0001). These studies in general indicate that the MN frequency in cytochalasin B-blocked human lymphocytes has the potential of serving as a quantitative biological dosimeter for the screening of radiation exposure to either healthy individuals or cancer patients.
The Effects of Micronuclei with Whole Chromosome on Biological Dose Estimation
2000
The total micronucleus (MN) assay has been used for purposes of biological dosimetry for many years. The variable spontaneous incidence of micronuclei in peripheral blood lymphocytes affects the sensitivity of biological dose estimations at low doses. It has been suggested that this problem could be solved by using the micronuclei-centromere assay. In this study, Co-60 gamma ray dose response curves
Atom Indonesia
Cytological biodosimetry methodology has been widely used for determining and estimating the precise irradiation dose received by victims in the situation of emergency irradiation exposure. The aim of this study was to assess the gamma-ray induced dicentric chromosomes and micronuclei (MN) in peripheral blood lymphocytes for preliminary reconstruction of cytogenetic biodosimetry. The study was performed by exposing blood samples taken from seven healthy donors to gamma rays at dose range of 0.1 to 4.0 Gy, followed by culturing them for 48-72 hours at 37 °C by the standard technique. After being harvested, the chromosome spread at metaphase and MN were stained with Giemsa's solution. The results showed that the frequency of both dicentrics and MN of samples were increased with the increase of radiation dose. Considerable increases of both cytologic damages were found in the samples exposed to higher doses (>2 Gy). Significant differences (p>0.05) only found in mean frequencies of MN for all doses tested. Reconstruction of the relationship of these frequencies with doses was found to follow linear-quadratic curve lines and was consistent with that of other studies. Due to the aforementioned advantages namely the dependence of radiation dose and dose rate on the frequency of of both dicentric and MN, despite some limitations, these assays have been found to be suitable to be used as biological dosimetry. It is concluded that in order for this cytogenetic biodosimety method by means of scoring/assessing the radiation-induced dicentrics and MN could be used in radiation emergency and protection, and further studies with larger numbers of samples need to be done.
Radiation and Environmental Biophysics, 2016
Developing new methods for radiation biodosimetry has been identified as a high priority need in case of a radiological accident or nuclear terrorist attacks. A large-scale radiological incident would result in an immediate critical need to assess the radiation doses received by thousands of individuals. Casualties will be exposed to different doses and dose-rates due to their geographical position and sheltering conditions, and dose-rate is one of the principal factors that determine the biological consequences of a given absorbed dose. In these scenarios high-throughput platforms are required to identify the biological dose in a large number of exposed individuals for clinical monitoring and medical treatment. The RABiT (Rapid Automated Biodosimetry Tool) is designed to be completely automated from the input of blood sample into the machine to the output of a dose estimate. The primary goal of this paper was to quantify the dose-rate effects for RABiTmeasured micronuclei in vitro in human lymphocytes. Blood samples from healthy volunteers were exposed in vitro to different doses of X-rays to acute and protracted doses over a period up to 24 hours. The acute dose (ADR) was delivered at ∼1.03Gy/min and the low dose rate (LDR) exposure at ∼0.31Gy/min. The results showed that the yield of micronuclei decreases with decreasing dose-rate starting at 2Gy, whereas response was indistinguishable from that of acute exposure in the low dose region, up to 0.5Gy. The results showed a linear-quadratic dose-response relationship for the occurrence of micronuclei for the acute exposure and a linear dose-response relationship for the low dose-rate exposure.
An in vitro study of the dose responses of human peripheral blood lymphocytes was conducted with the aim of creating calibrated dose-response curves for biodosimetry measuring up to 4 Gy (0.25-4 Gy) of gamma radiation. The cytokinesis-blocked micronucleus (CBMN) assay was employed to obtain the frequencies of micronuclei (MN) per binucleated cell in blood samples from 16 healthy donors (eight males and eight females) in two age ranges of 20-34 and 35-50 years. The data were used to construct the calibration curves for men and women in two age groups, separately. An increase in micronuclei yield with the dose in a linear-quadratic way was observed in all groups. To verify the applicability of the constructed calibration curve, MN yields were measured in peripheral blood lymphocytes of two real overexposed subjects and three irradiated samples with unknown dose, and the results were compared with dose values obtained from measuring dicentric chromosomes. The comparison of the results obtained by the two techniques indicated a good agreement between dose estimates. The average baseline frequency of MN for the 130 healthy non-exposed donors (77 men and 55 women, 20-60 years old divided into four age groups) ranged from 6 to 21 micronuclei per 1000 binucleated cells. Baseline MN frequencies were higher for women and for the older age group. The results presented in this study point out that the CBMN assay is a reliable, easier and valuable alternative method for biological dosimetry.
HELIYON , 2023
In the modern developing society, application of radiation has increased extensively. With significant improvement in the radiation protection practices, exposure to human could be minimized substantially, but cannot be avoided completely. Assessment of exposure is essential for regulatory decision and medical management as applicable. Until now, cytogenetic changes have served as surrogate marker of radiation exposure and have been extensively employed for biological dose estimation of various planned and unplanned exposures. Dicentric Chromosomal Aberration (DCA) is radiation specific and is considered as gold standard, micronucleus is not very specific to radiation and is considered as an alternative method for biodosimetry. In this study dose response curves were generated for X-ray induced “dicentric + ring” and micronuclei, in lymphocytes of three healthy volunteers [2 females (age 22, 23 years) and 1 male (24 year)]. The blood samples were irradiated with X-ray using LINAC (energy 6 MV, dose rate 6 Gy/min), in the dose range of 0–5Gy. Irradiated blood samples were cultured and processed to harvest metaphases, as per standard procedures recommended by International Atomic Energy Agency. Pooled data obtained from all the three volunteers, were in agreement with Poisson distribution for “dicentric + ring”, however over dispersion was observed for micronuclei. Data (“dicentric + ring” and micronuclei) were fitted by linear quadratic model of the expression Y– –C + αD + βD2 using Dose Estimate software, version 5.2. The data fit has resulted in linear coefficient α = 0.0006 (±0.0068) “dicentric + ring” cell− 1 Gy− 1 and quadratic coefficient β = 0.0619 (±0.0043) “dicentric + ring” cell− 1 Gy− 2 for “dicentric + ring” and linear coefficient α = 0.0459 ± (0.0038) micronuclei cell− 1 Gy− 1 and quadratic coefficient β = 0.0185 ± (0.0010) micronuclei cell− 1 Gy− 2 for micronuclei, respectively. Background frequencies for “dicentric + ring” and micronuclei were 0.0006 ± 0.0004 and 0.0077 ± 0.0012 cell− 1, respectively. Established curves were validated, by reconstructing the doses of 8 dose blinded samples (4 by DCA and 4 by CBMN) using coefficients generated here. Estimated doses were within the variation of 0.9–16% for “dicentric + ring” and 21.7–31.2% for micronuclei respectively. These established curves have potential to be employed for biodosimetry of occupational, clinical and accidental exposures, for initial triage and medical management.