Aberrations In Peripheral Blood Lymphocytes Research Articles

First application of the BIANCA biophysical model to carbon-ion patient cases

Objective. The main objective of this work consists of applying, for the first time, the BIANCA (BIophysical ANalysis of Cell death and chromosome Aberrations) biophysical model to the RBE calculation for C-ion cancer patients, and comparing the outcomes with those obtained by the LEM I model, which is applied in clinics. Indeed, the continuous development of heavy-ion cancer therapy requires modelling of biological effects of ion beams on tumours and normal tissues. The relative biological effectiveness (RBE) of heavy ions is higher than that of protons, with a significant variation along the beam path. Therefore, it requires a precise modelling, especially for the pencil-beam scanning technique. Currently, two radiobiological models, LEM I and MKM, are in use for heavy ions in scanned pencil-beam facilities. Approach. Utilizing an interface with the FLUKA Particle Therapy Tool, BIANCA was applied to re-calculate the RBE-weighted dose distribution for carbon-ion treatment of three patients (chordoma, head-and-neck and prostate) previously irradiated at CNAO, where radiobiological optimization was based on LEM I. The predictions obtained by BIANCA were based either on chordoma cell survival (RBE surv ), or on dicentric aberrations in peripheral blood lymphocytes (RBE ab ), which are indicators of late normal tissue damage, including secondary tumours. The simulation outcomes were then compared with those provided by LEM I. Main results. While in the target and in the entrance channel BIANCA predictions were lower than those obtained by LEM I, the two models provided very similar results in the considered OAR. The observed differences between RBE surv and RBE ab (which were also dependent on fractional dose and LET) suggest that in normal tissues the information on cell survival should be integrated by information more closely related to the induction of late damage, such as chromosome aberrations. Significance. This work showed that BIANCA is suitable for treatment plan optimization in ion-beam therapy, especially considering that it can predict both cell survival and chromosome aberrations and has previously shown good agreement with carbon-ion experimental data.

Ретроспективная оценка тяжести отдалённых лучевых повреждений онкологических пациентов методом цитогенетического обследования

This paper presents the results of the study of long-term effect of radiation therapy on patients with different types of cancer. The aim of the retrospective study was to evaluate effect of external beam radiation therapy (EBRT) for improving rehabilitation effectiveness. To estimate the effect a cytogenetic analysis of chromosomal aberrations in peripheral blood lymphocytes was performed. The group included patients for whom clarification, confirmation or refutation of the total focal dose (TFD) indicated in the epicrisis after EBRT was required. A group of 25 patients (5 males and 20 females) was examined. The patients had different types of cancer: Hodgkin’s lymphoma, cancer of breast and prostate glands, cervical and uterine cancers, bone cancer and multisite cancer. All examined patients underwent rehabilitation in the department of surgical and conservative treatment of radiation Injuries of A. Tsyb MRRC. For examination patient’s blood lymphocytes were stained followed by fluorescence or light microscopy to image first mitosis cells. To detect aberrations chromosome preparations with stained chromosomes 2, 4, and 12 were subjected to FISH analysis. Chromosomal aberration analysis was also used for dose assessment in accordance with IAEA recommendations. As a result, it was shown that the individual response of patients varies significantly under irradiation schemes comparable in terms of total dose and fractionation. A significant role is played by the factor of the time interval between the end of EBRT and the cytogenetic analysis (∆T). There was a clear excess of the observed frequency of aberrations in the first decade after EBRT compared with the subsequent time. The work did not reveal any dependence between the total frequency of aberrations, as well as its components, on the type of cancer disease. According to the preliminary conclusion, there is a basis for applying obtained estimates of the dose coefficient for retrospective biodosimetry of patients with the diseases listed in the group. The revealed patterns of chromosomal damage induction in blood lymphocytes of cancer patients prove the need for a personalized approach to planning and implementing a radical course of therapy in order to increase its effectiveness and prevent side effects.

CYTOGENETIC STUDY OF MANIFESTATIONS OF THE UNIVERSAL PHENOMENON OF THE BYSTANDER RESPONSE.

to establish the level of chromosomal instability in peripheral blood lymphocytes (PBL) from healthyindividuals and cells from patients with B-cell chronic lymphocytic leukemia (CLL) under co-cultivation conditions and to determine the possibility of inducing manifestations of the universal phenomenon of bystander response in them. Cytogenetic analysis of uniformly stained chromosomes from human PBL, which differed by cytogenetic markers of sex; the presence of oncological transformation and in vitro irradiation of 137Cs in a dose of 0.50 Gy under the conditions of their joint cultivation was performed. The frequency of chromosome aberrations in PBL from healthy individuals when co-cultured with the blood from CLL patients was 3.35 per 100 cells, exceeded the control (1.48 per 100 cells, р < 0.01), did not significantly differ from the rate in non-irradiated blood T-lymphocytes from patients with B-cell CLL (3.18 per 100 cells, р > 0.05) and was lower than when co-cultivated with irradiated blood from CLL patients (5.00 per 100 cells, р < 0.01). In irradiated in vitro blood lymphocytes from CLL patients, the mean group level of chromosome aberrations under separate cultivation was 12.36 per 100 cells and exceeded the indicator during their co-cultivation with lymphocytes from healthy individuals (8.35 per 100 cells, р < 0.05). A tumor-induced bystander effect (TIBE) develops in PBL from healthy individuals when co-cultured with the blood from CLL patients and in T lymphocytes of B-cell CLL patients, the cytogenetic manifestation of which is an increase in the frequency of single chromatid fragments. The interaction of irradiated blood cells from CLL patients with lymphocytes from healthy individuals causes an increase in chromosomal instability in the latter due to the development of a radiation-induced bystander effect (RIBE) and leads to a decrease in the level of chromosomal instability in irradiated lymphocytes from CLL patients (rescue effect). An increase in the level of chromatid-type aberrations in T-lymphocytes of CLL patients during in vitro irradiation is a consequence of the development of RIBE against the background of TIBE.

Dose estimation after a mixed field exposure: Radium-223 and intensity modulated radiotherapy

IntroductionRadium-223 dichloride ([223Ra]RaCl2), a radiopharmaceutical that delivers α-particles to regions of bone metastatic disease, has been proven to improve overall survival of men with metastatic castration resistant prostate cancer (mCRPC). mCRPC patients enrolled on the ADRRAD clinical trial are treated with a mixed field exposure comprising radium-223 (223Ra) and intensity modulated radiotherapy (IMRT). While absorbed dose estimation is an important step in the characterisation of wider systemic radiation risks in nuclear medicine, uncertainties remain for novel radiopharmaceuticals such as 223Ra. Methods24-Colour karyotyping was used to quantify the spectrum of chromosome aberrations in peripheral blood lymphocytes of ADRRAD patients at incremental times during their treatment. Dicentric equivalent frequencies were used in standard models for estimation of absorbed blood dose. To account for the mixed field nature of the treatment, existing models were used to determine the ratio of the component radiation types. Additionally, a new approach (M-FISHLET), based on the ratio of cells containing damage consistent with high-LET exposure (complex chromosomal exchanges) and low-LET exposure (simple exchanges), was used as a pseudo ratio for 223Ra:IMRT dose. ResultsTotal IMRT estimated doses delivered to the blood after completion of mixed radiotherapy (after 37 IMRT fractions and two [223Ra]RaCl2 injections) were in the range of 1.167 ± 0.092 and 2.148 ± 0.096 Gy (dose range across all models applied). By the last treatment cycle analysed in this study (four [223Ra]RaCl2 injections), the total absorbed 223Ra dose to the blood was estimated to be between 0.024 ± 0.027 and 0.665 ± 0.080 Gy, depending on the model used. Differences between the models were observed, with the observed dose variance coming from inter-model as opposed to inter-patient differences. The M-FISHLET model potentially overestimates the 223Ra absorbed blood dose by accounting for further PBL exposure in the vicinity of metastatic sites. ConclusionsThe models presented provide initial estimations of cumulative dose received during incremental IMRT fractions and [223Ra]RaCl2 injections, which will enable improved understanding of the doses received by individual patients. While the M-FISHLET method builds on a well-established technique for external exposures, further consideration is needed to evaluate this method and its use in assessing non-targeted exposure by 223Ra after its localization at bone metastatic sites.

Analysis on the status of occupational health of medical radiation workers in China in 2019

Objective: To grasp the occupational health monitoring of radiation workers in medical institutions across the country, and to discover weak links in the prevention and treatment of occupational radiation diseases. Methods: In 2020 January, according to the monitoring data of the "National Radiation Health Information Platform" (Occupational Radiation Disease and Occupational Health Monitoring Subsystem and Occupational Radiation Disease Reporting Subsystem) , the national occupational health monitoring data from January 1 to December 31, 2019, including the number of radiation workers in medical institutions, occupational health examinations, personal dose monitoring and occupational radiation disease diagnosis, were descriptive analyzed. Results: There were a total of 394436 radiation workers in medical institutions across the country. The number of radiation workers in various provinces was quite different, with a median of 10206, which was positively correlated with the number of permanent residents in each province (r=0.947) . There were 376 personal dose monitoring institutions nationwide, and the personal dose monitoring rate of radiation workers in medical institutions was 96.61% (381045/394436) . There were 419 occupational health inspection institutions for radiation workers across the country, and 269 (64.20%) used software to print physical examination forms. A total of 334455 radiation workers in medical institutions had been subjected to occupational health examinations. The rate of occupational health examinations for radiation workers in medical institutions was 84.79% (334455/394436) . The abnormal rate of chromosomal aberrations in peripheral blood lymphocytes of radiation workers in medical institutions was 0.33% (776/233571) , the detection rate of posterior posterior subcapsular turbidity was 0.63% (2093/334455) , and the abnormality rate of thyroid color ultrasound was 28.49% (14946/52464) . In 2019, a total of 16 cases of occupational radiation diseases were reported. Conclusion: The personal dose monitoring rate and occupational health examination rate of medical radiation workers nationwide are relatively high, but the quality of lymphocyte chromosome aberration analysis, eye lens examination and thyroid color photograph examination needs to be further improved.

Estimation of lymphocyte radiation doses after the ingestion of radionuclides of different tropicity

Assessment of the lymphocyte doses is relevant for solving a number of radiobiological problems, including the risk assessment of hemoblastosis (leukemia, multiple myeloma, lymphoma etc.), as well as the use of circulating lymphocytes as “natural biodosimeters”. The latter is because the frequency of chromosomal aberrations occurring in lymphocytes following radiation exposure is proportional to the accumulated dose. Assessment of doses to the circulating lymphocytes requires due account of: first, the dose accumulated by the lymphocyte progenitors in the red bone marrow; and second, the dose accumulated during lymphocyte circulation through lymphoid organs. The models presented by International Commission on Radiological Protection (ICRP-67, ICRP-100) allow calculating the dose for specific lymphoid organs based on known level of radionuclide intakes. A recently developed model of circulating T-lymphocyte irradiation takes into account all sources of exposure and age-related dynamics of T-lymphocytes: (1) exposure of lymphocyte progenitors in red bone marrow: (2) exposure of T-lymphocytes in the lymphoid organs, taking into account the proportion of resident lymphocytes and the residence time of circulating lymphocytes in the specific lymphoid organs. The objective of the study is to assess the dose coefficients allowing for the transition from the ingestion of 141,144Ce, 95Zr, 103,106Ru, 95Nb to the doses accumulated in circulating T-lymphocytes. For calculations, we used the dose coefficients from ICRP publications for specific lymphoid organs, as well as published data on the residence time of circulating lymphocytes in lymphoid organs and tissues. As a result, it was shown that the doses in circulating T-lymphocytes are higher than those in the red bone marrow, but lower than the doses to the colon wall. The dose coefficients were age dependent; the maximum values were typical for newborns. The obtained dose coefficients for 141,144Ce, 95Zr, 95Nb and 103,106Ru can be used to estimate the tissue and organ doses based on data on the frequency of chromosomal aberrations in peripheral blood lymphocytes.

Healthy Tissue Damage Following Cancer Ion Therapy: A Radiobiological Database Predicting Lymphocyte Chromosome Aberrations Based on the BIANCA Biophysical Model.

Chromosome aberrations are widely considered among the best biomarkers of radiation health risk due to their relationship with late cancer incidence. In particular, aberrations in peripheral blood lymphocytes (PBL) can be regarded as indicators of hematologic toxicity, which is a major limiting factor of radiotherapy total dose. In this framework, a radiobiological database describing the induction of PBL dicentrics as a function of ion type and energy was developed by means of the BIANCA (BIophysical ANalysis of Cell death and chromosome Aberrations) biophysical model, which has been previously applied to predict the effectiveness of therapeutic-like ion beams at killing tumour cells. This database was then read by the FLUKA Monte Carlo transport code, thus allowing us to calculate the Relative Biological Effectiveness (RBE) for dicentric induction along therapeutic C-ion beams. A comparison with previous results showed that, while in the higher-dose regions (e.g., the Spread-Out Bragg Peak, SOBP), the RBE for dicentrics was lower than that for cell survival. In the lower-dose regions (e.g., the fragmentation tail), the opposite trend was observed. This work suggests that, at least for some irradiation scenarios, calculating the biological effectiveness of a hadrontherapy beam solely based on the RBE for cell survival may lead to an underestimation of the risk of (late) damage to healthy tissues. More generally, following this work, BIANCA has gained the capability of providing RBE predictions not only for cell killing, but also for healthy tissue damage.

Spontaneous and induced chromosomal aberrations in peripheral blood of women with endometriosis: evidence of genomic instability.

Endometriosis is a prevalent gynecological disease which can lead to certain types of cancers. We investigated the spontaneous and induced chromosomal aberrations in peripheral blood lymphocytes (PBL) of endometriosis patients. We performed a pilot study utilizing mitomycin C (MMC) to assess chromosomal instability in the peripheral blood of participants. The patient group consisted of 20 infertile endometriosis patients and the controls of 20 healthy fertile women. Blood samples were collected, and two distinct lymphocyte cultures were prepared to evaluate the baseline and the MMC induced chromosomal aberrations. The results showed a significant difference before and after MMC treatment in both groups (P<0.001) and also revealed that endometriosis patients are far more sensitive to MMC than controls (P<0.001). The significantly higher frequency of induced and spontaneous chromosomal aberrations in patients can be consider as a sign of genomic instability and the defect in DNA repair mechanisms, which can be both assumed as a driver of cancer development in endometriosis patients.

Effects of brachytherapy on cytogenetic parameters and oxidative status in peripheral blood lymphocytes of gynecologic cancer patients.

The state-of-the-art brachytherapy technologies with high-dose sources of 60Co and 192Ir within contemporary treatment protocols for cancer patients allow achieving maximum dose distribution in the clinical target and with minimum radiation exposure of surrounding organs and tissues. For minimization and overcoming the early and late radiation complications, development of respective radiobiological criteria along with perfecting of physical and technical characteristics of the ionizing radiation sources are required. To study the effect of 192Ir radiation on the chromosomal aberrations and prooxidant/antioxidant status of blood lymphocytes in gynecological cancer patients. The patients (n= 45) with endometrial, cervical and secondary cancer of vagina were enrolled in the study. For brachytherapy, the irradiation of vaginal mucosa was conducted using "GammaMed plus" device for contact radiation therapy with 192Ir source. Prior to irradiation and in 20-24h after brachytherapy session, the venous blood samples were obtained and peripheral blood lymphocytes (PBL) were cultured for cytogenetic analysis. The prooxidant/antioxidant status was determined in hemolysates by the method of hydrogen peroxide-induced chemiluminescence. The average level of spontaneous chromosome aberrations in PBL of the patients was (7.8± 0.4) per 100metaphases, which is more than twice higher than the upper limit of the average population values. The frequency of chromosome aberrations in PBL of patients after brachytherapy session was (15.3± 1.0) per 100metaphases. An increased intensity of O2- generation by PBL after brachytherapy session was also noticed. Local irradiation at a dose of 6Gy featuring the first dose fraction of brachytherapy induces extra chromosomal aberrations in PBL of gynecological cancer patients and intensifies prooxidant processes in the blood.

Значимость персональных клинико-диагностических показателей при оценке побочного радиационного воздействия для больных раком щитовидной железы, получающих радиойодтерапию

The radioiodine therapy is the most well-known branch of radionuclide therapy. The therapy composed of thyroidectomy and iodine-131 radiopharmaceutical is the “gold standard” for treat-ment of differentiated thyroid cancer patients (DTC). Given metastases in lymph nodes such therapy is absolutely exclusive treatment mode. At the same time, despite the targeted effect of radioiodine on pathological foci a side internal exposure of healthy organs and tissues is noted in the course of radioiodine therapy. Therefore, a reliable assessment of the side exposure is nec-essary taking into account the individual characteristics of patients considering that the side dose varies significantly from patient to patient. For this reason, the identification of significance of personal clinic-diagnostic factors determined the side whole body exposure is the vital and im-portant task. In this aspect, the cytogenetic examination of DTC patients by means of the analysis of chromosomal aberrations in peripheral blood lymphocytes is the goal of essential importance. The certain types of chromosomal aberrations are specific radiation markers that unequivocally indicate radiation exposure. Using the frequency of radiation markers the side absorbed dose can be reliably estimated. In the present work, the statistical analysis of the significance of vari-ous clinic-diagnostic factors in relation to the induction of radiation markers in the blood lympho-cytes was performed. For that end the results of the cytogenetic examination of the group com-prised of 38 DTC patients have been used. The examined patients underwent a course of radio-iodine therapy in the department of radionuclide therapy of the A.F. Tsyb MRRC, Obninsk. The slide preparation and cytogenetic analysis were carried out in the laboratory of radiation cytoge-netic of the same Center. The performed analysis of the correlation matrix with respect to the dependence of the increased frequency of stable and unstable markers resulted from a one-time course of radioiodine therapy showed no meaningfulness at the level R&gt;0.3 for all the studied factors. For the absolute value of the frequency of radiation markers, both before and after radioiodine therapy, the meaningful relationship was found at the level R&gt;0.7 for unsta-ble and at the level R&gt;0.8 for stable markers with a total administered activity of radioiodine dur-ing all the previous courses of radioiodine therapy.

CYTOGENETIC INDICATORS OF ACUTE RADIATION SICKNESS (THE CHORNOBYL EXPERIENCE).

The study was based on primary cytogenetic data obtained in May 1986 within examina-tion of the 30 clean-up workers («liquidators») having got stage I-III acute radiation sickness. Dose verificationwas performed using the cytogenetic dosimetry based on a culture of peripheral blood lymphocytes with metaphaseanalysis of chromosome aberrations. A new method of evaluating the results of patients' cytogenetic examination at the beginning of specifictherapy has been developed. Procedure was performed using a model of multiple linear regression (complex of cyto-genetic parameters) and provided a satisfactory diagnostic level (featuring a compliance with initially definedclinical and laboratory diagnoses). Overall frequency of the aberrant cells and radiation markers increased in high-er disease stages. There was a trend of the frequency growth of chromatid-type aberrations with increasing of radi-ation burden. Adequacy of the proposed method based on the regression analysis of cytogenetic results was con-firmed through the preservation of group differences in estimates of disease stage in subjects with verified diagnosis. Cytogenetic dosimetry in the scope of examination of persons exposed to ionizing radiation is an oblig-atory component of radiation sickness stage verification. The recommended method of cytogenetic data evaluationbefore and at the beginning of detoxification therapy provides a satisfactory level of diagnostics.

Rogue cell-like chromosomal aberrations in peripheral blood lymphocytes of interventional radiologists: A case study

We report two cases of interventional radiologists who had been exposed to radiation while performing fluoroscopically-guided interventional procedures (FGIPs), mainly transcatheter arterial chemoembolization, percutaneous catheter drainage, and percutaneous transhepatic biliary drainage procedures, for over 10 years. They had a unique multi-aberrant cell type with not only high numbers of dicentrics and/or centric rings but also excess acentric double minutes, similar to a rogue cell. As revealed in a self-administered questionnaire, they wore personal dosimeters and protective equipment at all times and used shielding devices during interventional fluoroscopy procedures. However, the exposed dose levels derived from cytogenetic dosimetry were much higher than the doses recorded on their personal dosimeters. A large number of unstable and stable chromosomal aberrations that were found in the peripheral blood lymphocytes of these interventional radiologists might be due to repeated and long-term exposure to ionizing radiation while performing FGIPs. Further investigations of chromosomal aberrations in interventional radiologists may improve the understanding of the long-term effects of radiation exposure on medical personnel.

Analysis of Chromosomal Aberrations and γH2AX Foci in Peripheral Blood Lymphocytes Induced By Chemoradiotherapy of Patients with Esophageal Cancer

The purpose of this study was to evaluate DNA damage and chromosomal aberrations in peripheral blood lymphocytes (PBLs) by chemoradiotherapy (CRT) in patients with esophageal cancer and to figure out the relationship between DNA damage and toxicities by CRT. Twelve esophageal cancer patients who received CRT were enrolled in this study. Prescribed doses were 60 Gy in 9 patients and 50 Gy in 3 patients. Patients received 2 Gy radiotherapy (RT) every 24 hours five days a week. Cisplatin (days 1 and 29) and 5-fluorouracil (days 1–4 and 29–32) were used as chemotherapy. We obtained PBLs just before and at 15 minute after RT on the day when the cumulative dose reached 2 Gy, 20 Gy, 40 Gy, and 50 or 60 Gy (the last day of RT). PBLs were also obtained at 4 weeks and 6 months after RT from all and five patients, respectively. Dicentric and ring chromosomes in PBLs were counted using fluorescence in situ hybridization analysis method with centromere and telomere peptide nucleic acid probes (PNA-FISH) to evaluate the number of chromosomal aberrations for each cumulative dose. γH2AX foci per cell were counted and the increment of γH2AX foci by 2 Gy RT for each day was calculated to assess DNA double-strand breaks. Adverse events were evaluated using common terminology criteria for adverse events version 4.0. Students t test was used to compare the mean value between two groups and p value < 0.05 was considered statistically significant. The mean numbers of chromosomal aberrations per 1,000 cells were increased during CRT as follows; Before RT: 18 (range: 0 – 53), 2 Gy: 80 (49 – 268), 20 Gy: 529 (288 – 1010), 40 Gy: 749 (392 – 1333), the last day of RT (50 Gy or 60 Gy): 1217 (794 – 2296), 4weeks after RT: 1128 (455 – 2063) and 6 months after RT: 512 (388 – 581). On the other hand, the mean number of γH2AX foci per cell before RT showed no increase during CRT. The mean increment of γH2AX foci per cell by 2 Gy RT was significantly reduced as follows; 2 Gy: 2.57 (1.01 –3.75), 20 Gy: 2.48(1.18 –3.85), 40 Gy: 1.52 (0.07 – 2.84), the last day of RT (50 Gy or 60 Gy): 1.34 (0.44 – 3.47), even though the same dose was administered each day. Four out of twelve patients showed grade 3 toxicities (three esophagitis and one pneumonitis) during or after CRT. The numbers of chromosomal aberrations on the last day of RT were significantly higher in those with grade 3 toxicities than those without grade 3 or worse toxicities. (mean value: 1609 vs 851, p=0.007) The mean increment of γH2AX foci by 2 Gy RT on the last day was also significantly higher in those with grade 3 toxicities than those without grade 3 or worse toxicities. (mean value: 2.20 vs 0.75, p=0.008) The number of chromosomal aberrations after CRT increased as the cumulative doses increased, while the increment of γH2AX foci decreased with an increase in cumulative dose. The numbers of chromosomal aberrations and the increment of γH2AX foci on the last day of RT seemed to correlate the severity of toxicities by CRT for esophageal cancer patients.

Features of the chromosomal apparatus in patients with juvenile idiopathic arthritis with concomitant multifactorial pathology

Aim. To determine the level of chromosomal disorders in peripheral blood lymphocytes of children and adolescents with juvenile idiopathic arthritis with concomitant multifactorial pathology in vitrо. Methods. Cytogenetic analysis was carried out in patients with juvenile idiopathic arthritis with concomitant multifactorial pathology in vitro, using a common methodology. Statistical analysis of the results of research was carried out using Excel software package and SPSS Statistics 17.0. Results. Chromosomal aberrations in peripheral blood lymphocytes were revealed in 100 % of patients. The general level of chromosomal abnormalities in the patients with concomitant pathology was 5.57 per 100 cells, and in the comparison group – 4.10 per 100 cells. In both groups aberrations of chromatid type prevailed. Conclusions. In patients with juvenile idiopathic arthritis, accompanied by different multifactorial disorders, spontaneous level of chromosomal abnormalities in blood lymphocytes in vitro was 1.4 times higher compared to the level of chromosomal aberrations in patients without concomitant pathology. The frequency of chromatid type aberrations was higher than the chromosome type aberrations rate in 1.6 times in the main group and in 2.2 times in the comparison group.&#x0D; Keywords: juvenile idiopathic arthritis, children, adolescents, chromosomes, aberrations, concomitant multifactorial pathology.

Frequency of Spontaneous and Radiation-Induced Chromosomal Aberrations in Peripheral Blood Lymphocytes of Individuals of Different Ages

The frequency of spontaneous and X-ray-induced (0.25 Gy) in vitro chromosomal aberrations, as well as the level of chromosomal instability as a result of the bystander effect, in the blood lymphocytes of individuals aged from 12 to 102 years has been investigated using GTG staining of human metaphase chromosomes. The average group frequency of spontaneous chromosomal aberrations in adolescents (12–16 years), middle-aged people (33–52 years), and centenarians (90–102 years) was identical (p > 0.05), whereas it was higher in elderly people (60–70 years) due to increase of chromatid type aberrations rate (p 0.05); however, the total frequency of chromosomal aberrations in individuals aged 60–70 years exceeded the value of such indices in other age groups due to the chromosomal type damages (p < 0.05). In nonirradiated blood lymphocytes of adolescents, middle-aged, and elderly individuals cocultivated with lymphocytes irradiated in vitro (0.25 Gy), the induction of the bystander effect was detected. In lymphocytes of centenarians, the development of the bystander effect was not detected.

Persistence of radiation-induced aberrations in patients after radiotherapy with C-ions and IMRT

Background and purposeChromosomal aberrations in peripheral blood lymphocytes are a biomarker for radiation exposure and are associated with an increased risk for malignancies. To determine the long-term cytogenetic effect of radiotherapy, we analyzed the persistence of different aberration types up to 2.5 years after the treatment. Materials and methodsCytogenetic damage was analyzed in lymphocytes from 14 patients that had undergone C-ion boost + IMRT treatment for prostate cancer. Samples were taken immediately, 1 year and 2.5 years after therapy. Aberrations were scored using the multiplex fluorescence in situ hybridization technique and grouped according to their transmissibility to daughter cells. ResultsDicentric chromosomes (non-transmissible) and translocations (transmissible) were induced with equal frequencies. In the follow-up period, the translocation yield remained unchanged while the yield of dicentrics decreased to ≈40% of the initial value (p = 0.011 and p = 0.001 for 1 and 2.5 years after compared to end of therapy). In 2 patients clonal aberrations were observed; however they were also found in samples taken before therapy and thus were not radiotherapy induced. ConclusionThe shift in the aberrations spectrum towards a higher fraction of translocations indicates the exposure of hematopoietic stem and progenitor cells underlining the importance of a careful sparing of bone marrow during radiotherapy to minimize the risk for secondary cancers.

Assessment of Cytogenetic Abnormalities by FISH in Lymphocytes from a Victim Accidentally Exposed to Cobalt-60

Background: A radiation accident occurred on 14 June 2011 in an industrial facility in Bulgaria whit Co source (137 TBq) used to sterilise equipment. Five people received doses exceed 1Gy and led to development of acute radiation syndrome. Biological dosimetry based on dicentric analysis was performed and the averaged acute whole-body doses estimated for the five patients were from 1.2 to 5.6 Gy. The purpose of this study was to evaluate in vivo induced chromosome aberrations four months after accident in the most severely exposed subject. Methods: Fluorescence plus Giemsa (FPG) staining and Fluorescent in situ hybridisation (FISH) were used to detect chromosomal aberrations in peripheral blood lymphocytes from the study subject four months after accidental exposure. FISH was provide using DNA probes specific for whole chromosomes #1, #4 and #11. Results: The mean frequency of dicentrics per cell ±SE was 0,425±0,042 determined by FPG. By FISH analysis the genomic frequency of apparently simple translocations (AST) per cell was 0,707±0,030. Incomplete translocations account for about 35%. For apparently simple dicentrics (ASD) the genomic frequency was calculated as 0,190±0,020. The frequency of complete plus incomplete dicentrics was 0,275 ± 0,020. Chromosome 1 was found to be involved in 52,35% of the total yield. Chromosome 4 was found to be involved in 30,2 % and chromosome 11 was involved in 22,82% of the total yield of translocations. Among 157 aberrant cells 28 cells or 17,83% were with one or more complex exchanges. Conclusions: This is a pilot study for a long time follow up assessing in vivo cytogenetic abnormalities in radiation accidentally exposed in Bulgaria persons. It is not possible at this to relate high frequency of translocation with long-term biological effect, but it is well known fact that ionizing radiation increase cancer risk in some individuals.

CORAL: Building up QSAR models for the chromosome aberration test.

A high level of chromosomal aberrations in peripheral blood lymphocytes may be an early marker of cancer risk, but data on risk of specific cancers and types of chromosomal aberrations are limited. Consequently, the development of predictive models for chromosomal aberrations test is important task. Majority of models for chromosomal aberrations test are so-called knowledge-based rules system. The CORAL software (http://www.insilico.eu/coral, abbreviation of “CORrelation And Logic”) is an alternative for knowledge-based rules system. In contrast to knowledge-based rules system, the CORAL software gives possibility to estimate the influence upon the predictive potential of a model of different molecular alerts as well as different splits into the training set and validation set. This possibility is not available for the approaches based on the knowledge-based rules system. Quantitative Structure–Activity Relationships (QSAR) for chromosome aberration test are established for five random splits into the training, calibration, and validation sets. The QSAR approach is based on representation of the molecular structure by simplified molecular input-line entry system (SMILES) without data on physicochemical and/or biochemical parameters. In spite of this limitation, the statistical quality of these models is quite good.

Serum miR-375-3p increase in mice exposed to a high dose of ionizing radiation

Exposure to high-doses of ionizing radiation (IR) leads to development of a strong acute radiation syndrome (ARS) in mammals. ARS manifests after a latency period and it is important to develop fast prognostic biomarkers for its early detection and assessment. Analysis of chromosomal aberrations in peripheral blood lymphocytes is the gold standard of biological dosimetry, but it fails after high doses of IR. Therefore, it is important to establish novel biomarkers of exposure that are fast and reliable also in the high dose range. Here, we investigated the applicability of miRNA levels in mouse serum. We found significantly increased levels of miR-375-3p following whole body exposure to 7 Gy of X-rays. In addition, we analyzed their levels in various organs of control mice and found them to be especially abundant in the pancreas and the intestine. Following a dose of 7 Gy, extensive cell death occurred in these tissues and this correlated negatively with the levels of miR-375-3p in the organs. We conclude that high expressing tissues of miR-375-3p may secrete this miRNA in serum following exposure to 7 Gy. Therefore, elevated miR-375-3p in serum may be a predictor of tissue damage induced by exposure to a high radiation dose.

Chromosome aberrations in peripheral blood lymphocytes of lung cancer patients exposed to radon and air pollution.

Lung cancer is one of the most common forms of cancer. The aim of this study was to validate chromosome aberrations in peripheral blood lymphocytes of lung cancer patients living in a region with high air pollution and increased background radon levels as a biomarker of cancer risk. A total of 417 lung cancer patients and 468 control participants were analysed using a chromosome aberration assay in peripheral blood lymphocytes. The results showed that chromatid-type aberrations (2.26±1.58 vs. 1.60±1.58) and chromosome-type aberrations (CSAs) (0.96±1.36 vs. 0.42±0.70) in lung cancer patients were increased significantly in comparison with the controls. The most significant two-fold increase was detected for CSAs (nonsmoking patients: 0.84±1.54 vs. 0.41±0.73%, smoking patients: 0.99±1.31 vs. 0.44±0.67%). The frequency of dicentric and ring chromosomes, double minutes and rogue cells was significantly higher (P=0.002, 0.00002, 0.01, 0.0007) in the lung cancer patients. As both analysed groups lived in the same environment, our results show that increased radon levels were not the only source for the detected genome damage. Using binomial logistic regression, the estimated odds ratios and 95% confidence intervals adjusted for the main confounders (smoking, occupational exposure, age) were 1.31 (1.20-1.40) for chromatid-type aberrations, 1.28 (1.17-1.33), and 1.68 (1.49-1.88) for CSAs. It may be suggested that lung cancer patients show a significant increase in genome damage that may be caused by an interplay between exposure and individual low capacity of DNA repair, leading to genome instability.