The Role of Bak1 Methylation in the Induction of Chromosomal Aberrations under Chronic Low-Intensity External Radiation

Purpose: To study the relationship between the methylation status of the Bаk1 promoter and the frequency of chromosomal aberrations in human blood lymphocytes under chronic low-intensity external ionizing radiation. Material and methods: The study was performed on 41 people (31 men and 10 women, aged from 36 to 83 years) who are former or current employees of the Siberian Group of Chemical Enterprises, who have been exposed or haven't been exposed to chronic low-intensity external radiation in the course of their professional activities. The workers included in the study were divided into two groups: the first – 15 people who did not have exposure, the second – 26 people who had external exposure (gamma radiation, total dose 89–716 mSv). Whole blood was used to isolate DNA and evaluate chromosomal aberrations in lymphocytes. The methylation status of the Bаk1 promoter was determined using methylsensitive PCR, which was performed after pretreatment of the isolated DNA with methylsensitive AoxI restrictase. The obtained quantitative data were analyzed using the Statistica 10. The differences were considered statistically significant at p ≤ 0.05. Results: The methylation status of the Bаk1 promoter in the study groups does not differ (p = 0.18). The study of the effect of external radiation dose on the methylation status of the Bak1 promoter showed that the unmethylated promoter prevails in workers with an average radiation dose of 273.37 ± 43.82 mSv, while the methylated promoter – in workers with an average radiation dose of 183.63 ± 20.58 mSv (p = 0.03). The unmethylated promoter Bаk1 is associated with an increased frequency of chromatid fragments in the blood lymphocytes of group 2 workers (p = 0.03). Conclusion: The status of methylation of the Bаk1 promoter in human blood lymphocytes under chronic low-intensity ionizing radiation does not change, but it is observed to depend on the radiation dose and is associated with an increased frequency of chromosomal aberrations (chromatid fragments). Thus, the unmethylated Bаk1 promoter prevails when the external radiation dose is increased. An increase in the frequency of chromatid fragments is associated with an unmethylated Bаk1 promoter. In addition, exposure to chronic low-intensity external radiation is accompanied by a decrease in the frequency of chromosomal fragments in the blood lymphocytes of workers of the Siberian Group of Chemical Enterprises.

Pengukuran Dosis Eksternal Yang Diterima Oleh Mahasiswa Praktikum Teknik Radiografi di Laboratorium Radiologi Universitas Baiturrahmah Padang

The utilization of ionizing radiation in the form of X-rays in addition to providing benefits to the medical world also has the potential to have a detrimental effect on workers, patients and, society. Radiation protection is a very important aspect of controlling this adverse effect. Every utilization of ionizing radiation must have endeavored so that the reception of radiation doses by radiation workers is always as low as possible so that the prescribed dose limit (NBD) value is not exceeded. NBD for apprentices and students who are as low as 18 years old, who are carrying out training or practical work, or who because of their educational needs are forced to use a source of ionizing radiation, the same as the NBD that applies to radiation workers. Dose limit values for radiation workers must not exceed 20 mSv (twenty millisieverts) per year on average for five consecutive years. Determination of the external radiation dose received by practicum students at the Baiturrahmah University Radiology Laboratory aims to calculate how much the external radiation dose received by students during carrying out one course. Based on the results of the study found that the measurement of external radiation dose received by the student is 0 or there is no scattering radiation received by students, this is because at the time of exposure they are in the correct position that is behind the control panel wall that has been coated with Lead (Pb).

INVESTIGATION OF EXTERNAL RADIATION DOSES DURING RESIDENTS’ TEMPORAL STAY TO NAMIE TOWN, FUKUSHIMA PREFECTURE

Namie Town in Fukushima Prefecture, the majority of which was an evacuation area as a result of the effects of the Fukushima Daiichi Nuclear Power Plant accident, carried out a ‘temporal stay’ in September 2016 so that residents could check their houses. Therefore, in cooperation with the town authorities, the authors distributed personal dosemeters and behaviour record forms to record the personal dose equivalent rate and investigate the relationship between residents’ external radiation dose and their behaviour. When the personal dose equivalent rate was calculated from the measured personal dose equivalent per hour, the median was 0.12 μSv h−1, the maximum value and the minimum value were 0.58 and 0.06 μSv h−1, respectively. Meanwhile, since personal fluctuations were observed in personal dose equivalent, grasping the relationship between residents’ behaviour and exposed dose can be applied to risk communication.