Cytogenetic Effects in Patients after Computed Tomography Examination.

Millions of people around the world are exposed to low doses of ionizing radiation from diagnostic computed tomography (CT) scans. Currently available data on the potential cancer risk after CT scans are contradictory and therefore demand further investigations. The aim of the current study was to obtain estimations of genome damage after CT scans in 42 non-cancer patients and to conduct a comparison of the results with 22 control subjects. The frequency of dicentric ring chromosomes and chromosome breaks was significantly increased in irradiated patients compared to the controls. The distribution of dicentrics among the cells demonstrated non-Poisson distribution that reflected non-uniform and partial-body radiation exposure. A fraction of patients followed Poisson distribution, which is typical for uniform whole-body exposures. Some patients demonstrated a level of dicentrics similar to the control subjects. The individual variations in the frequency and dicentric distribution suggested complex mechanisms of chromosome aberration induction and elimination that could be associated with individual radiosensitivity, as well as previous diagnostics that used ionizing radiation or the redistribution of small fractions of irradiated lymphocytes within the circulatory pull. In conclusion, CT scans may cause genome damage and possible increases in cancer risk. The introduction of a specific follow-up of such patients, especially in the case of repeated CT scans, is suggested.

Follow-up studies on genome damage in children after Chernobyl nuclear power plant accident.

As children are more susceptible to ionizing radiation than adults, each nuclear accident demands special attention and care of this vulnerable population. The Chernobyl nuclear disaster occurred in a region populated with a large number of children, but despite all efforts and expertise of nuclear specialists, it was not possible to avoid casualties. As vast regions of Ukraine, Belarus and Russia were exposed to doses of ionizing radiation, which are known to be related with different diseases, shortly after the accident medical surveillance was launched, which also included analysis of genome damage. Child population affected by internal and external radiation consisted of subjects exposed prenatally, postnatally (both evacuated and non-evacuated), born by irradiated fathers who worked as liquidators, and parents exposed environmentally. In all groups of children during the last 30 years who were exposed to doses which were significantly higher than that recommended for general population of 1 mSv per year, increased genome damage was detected. Increased genome damage includes statistically higher frequency of dicentric and ring chromosomes, chromated and chromosome breaks, acentric fragments, translocations, and micronuclei. The presence of rogue cells confirmed internal contamination. Genome instability and radiosensitivity in children was detected both in evacuated and continuously exposed children. Today the population exposed to ionizing radiation in 1986 is in reproductive period of life and follow-up of this population and their offspring is of great importance. This review aims to give insight in results of studies, which reported genome damage in children in journals without language restrictions.

Construction of Calibration Curve for Premature Chromosome Condensation Assay for Dose Assessment.

Cytogenetic dosimetry plays an important role in the triage and medical management of affected people in radiological incidents/accidents. Cytogenetic biodosimetry uses different methods to estimate the absorbed dose in the exposed individuals, and each approach has its advantages and disadvantages. Premature chromosome condensation (PCC) assay presents several advantages that hopefully fulfill the gaps identified in the other cytogenetic methods. To introduce this technique into the panel of other cytogenetic methods, a calibration curve for PCC after γ-irradiation was generated for our laboratory.

Chromosomal aberrations and sickness rates in Chernobyl clean-up workers in the years following the accident.

The aim of this investigation was to reveal a possible correlation between chromosomal aberrations and the health status of Chernobyl clean-up workers who suffered from a low dose of ionizing radiation. Unstable chromosomal aberrations in peripheral blood lymphocytes were investigated in 491 Chernobyl clean-up workers. Information about lifestyle factors (all persons) and medical history (212 persons) was collected. Connections between the rate of chromosomal aberrations and some types of diseases were found. It was also found that Chernobyl clean-up workers with oncological diseases and hypertension had increased rates of chromosomal aberrations. Positive correlations between the grade of hypertension and the level of chromosomal aberrations (r = 0.20, p < 0.01) was revealed. Further investigations need to be carried out in order to understand the mechanisms of this connection.

Chromosome alterations in cleanup workers sampled years after the Chernobyl accident.

Cytogenetic analysis performed 4-13 years after the Chernobyl accident showed an elevated frequency of acentrics, chromatid exchanges, dicentrics and rings in Chernobyl cleanup workers compared to the control group. Cytogenetic data were analyzed according to the information on exposure to radiation (the year when the cleanup workers worked at the Chernobyl station, doses rates, time elapsed since exposure to radiation, and cytogenetic examination) and some lifestyle factors. The data obtained suggested that some types of chromosome aberrations could be influenced by the action of different environmental factors or lifestyle factors. The frequency of acentrics was correlated with the age of the cleanup workers, and the increased chromatid exchange frequency was attributed to smoking. The numbers of dicentrics and rings suggested a genotoxic effect of ionizing radiation that is still present over 13 years after the exposure.