Genetic polymorphisms in XRCC1, OGG1, APE1 and XRCC3 DNA repair genes, ionizing radiation exposure and chromosomal DNA damage in interventional cardiologists

Occupational Risks of Radiation Exposure to Cardiologists

PURPOSE OF REVIEW

Invasive cardiologists are exposed to large amounts of ionizing radiation. This review aims to summarize the main occupational risks in a radiation-exposed cardiology practice.

RECENT FINDINGS

We carried out a literature review on the subject. The studies reviewed allowed us to list six main health risk categories possibly associated with radiation exposure among cardiologists: deoxyribonucleic acid (DNA) and biochemical damages; cancers; ocular manifestations; olfaction, vascular, and neuropsychological alterations; musculoskeletal problems; and reproductive risks. Our descriptive analysis demonstrates higher risks of DNA damage and lens opacities among radiation-exposed cardiology staff. Surveys and questionnaires have demonstrated a higher risk of musculoskeletal disease in exposed workers. Studies reported no difference in cancer frequency between radiation-exposed workers and controls. Changes in olfactory performance, neuropsychological aspects, and vascular changes have also been reported. Limited literature supports the security of continuing radiation-exposed work during pregnancy. Therefore, there is an urgent need to increase knowledge of the occupational risks of radiation exposure and to adopt technologies to reduce them.

The Long-Term Impact of Ionizing Radiation on DNA Damage in Patients Undergoing Multiple Cardiac Catheterizations

Ionizing radiation (IR) exposures have increased exponentially in recent years due to the rise in diagnostic and therapeutic interventions. A number of small-scale studies investigated the long-term effect of IR on health workers or immediate effects of IR on patients undergoing catheterization procedures; however, the long-term impact of multiple cardiac catheterizations on DNA damage on a patient population is not known. In this study, the effects of IR on DNA damage, based on micronuclei (MN) frequency and 8-hydroxy-2'-deoxyguanosine (8-OHdG) as markers in peripheral lymphocytes, were evaluated in patients who previously underwent multiple cardiac catheterization procedures. Moreover, genetic polymorphisms in genes PARP1 Val762Ala, OGG1 Ser326Cys, and APE1 Asn148Glu as a measure of sensitivity to radiation exposure were also investigated in the same patient population. The patients who underwent ≥ 3 cardiac catheterization procedures revealed higher DNA injury in comparison to the patients who underwent ≤ 2 procedures, documented with the presence of higher level of MN frequency (6.4 ± 4.8 vs. 9.1 ± 4.3, p = 0.002) and elevated serum 8-OHdG levels (33.7 ± 3.8 ng/mL vs. 17.4 ± 1.9 ng/mL, p = 0.001). Besides, OGG1 Ser326Cys and APE1 Asn148Glu heterozygous and homozygous polymorphic types, which are related with DNA repair mechanisms, were significantly associated with MN frequency levels (p = 0.006 for heterozygous and p = 0.001 for homozygous with respect to OGG1 Ser326Cys, p = 0.007 for heterozygous and p = 0.001 for homozygous with respect to APE1 Asn148Glu). There was no significant difference in terms of PARP1 Val762Ala gene polymorphism between two groups.

Association of buccal micronucleus cytome assay (BMNCyt) biomarkers with inorganic element concentration and genetic polymorphisms in welders

Welding fumes are classified as carcinogenic to humans. The aim of the present study was to measure buccal micronucleus cytome assay biomarkers and to evaluate their association with inorganic elements and genetic polymorphisms (XRCC1, OGG1, XRCC3, GSTM1, and GSTT1) in welders (n = 98) and control individuals (n = 100). Higher levels of DNA damage and cell death were observed in the exposed group. Also, a significant correlation between the frequency of micronuclei and Na, Si, Cl, Ti, Cr, Zn and Mg concentrations. The formation of micronuclei, binucleated cells, cell death was associated with polymorphisms in repair pathways. The OGG1Ser326Cys and XRCC3 241Thr/Met genotypes were associated with cell death. Individuals with GSTM1 null genotype had a higher frequency of micronuclei. These results demonstrate that the deleterious effects of exposure to welding fumes are exacerbated by lifestyle habits, and genetic polymorphisms can influence DNA damage and cell death.

Telomere fragility in radiology workers occupationally exposed to low doses of ionising radiation

Ionising radiation damages DNA directly and indirectly through increased production of reactive oxygen species. Although telomeres have been reported as indicators of radiosensitivity, their maintenance in response to occupational exposure to low radiation doses is still a matter of debate. In this work we aimed to investigate telomere length and structure in hospital workers occupationally exposed to X-rays and to relate these findings to oxidation of biomolecules and chromosome aberrations. Blood samples of exposed participants and matching controls were taken during periodical check-ups. Chromosome aberrations and telomere length and structure were analysed in peripheral blood lymphocytes using Q-FISH, whereas oxidative stress parameters [pro/antioxidant balance (PAB), lipid peroxidation, and 8-oxo-dG] were measured in plasma samples. Based on the CA findings we divided the exposed group into two subgroups, of which one had chromosome aberrations in the first division metaphases and the other did not. There was no significant difference in telomere length between any of the groups. However, both subgroups showed significantly higher rate of fragile telomeres and higher lipid peroxidation product and 8-oxo-dG levels than controls. The rate of fragile telomeres significantly correlated with plasma levels of 8-oxo-dG, which suggests that continuous exposure to low radiation doses induces oxidative base damage of guanine resulting in telomere fragility.

The modulation of oxidative stress and DNA damage to radiology technicians by repair enzymes XRCC1 and XRCC3 The association of oxidative stress and DNA damage with XRCC1 and XRCC3 polymorphisms in radiology technicians

Ionizing radiation has widespread use in medicine in the diagnosis and treatment of many medical conditions. Radiology technicians are one group that is occupationally exposed to low doses of radiation. There are questions regarding whether low dose exposure to radiation could have long-term health consequences. Assessing the effect of radiation on genetic material is essential for appraising long-term health results. Hereditary variations in DNA repair genes cause differentiation in individual responses to radiation related health effects. This study aimed to determine oxidative stress and DNA damage, and their relationship to XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) polymorphisms in radiology technicians occupationally exposed to low dose radiation. Peripheral blood samples were collected from 45 radiology technicians and age-matched with 40 healthy control individuals working in office environments. Our results showed that radiology technicians had significantly greater oxidative stress and DNA damage than the control group, and women appeared more susceptible to occupational radiation exposure than men. Individuals with wild-type genotypes for XRCC1 (Arg/Arg) and XRCC3 (Thr/Thr) had less DNA damage. Lower DNA damage levels could be explained by the enhanced capacity to repair low dose radiation induced DNA damage. Further studies are needed to evaluate the role of DNA repair genes in individuals that are occupationally exposed to low dose radiation.

Changes in Growth, Morphology, and Physiology of Tetrahymena pyriformis Exposed to Continuous Cesium-137 and Cobalt-60 Gamma-Radiation

This study investigated the effects of gamma-radiation on Tetrahymena pyriformis. The experimental approach consists of exposing T. pyriformis growing in presence of Cesium-137 (¹³⁷Cs) at dose rates of 1, 2, 4, and 6 cGy h^-1 and Cobalt-60 (⁶⁰Co) at dose rates of 8, 10, 15, and 20 cGy h^-1. The radiation doses effects on growth, morphology, some metabolic enzymes, and reactive oxygen species (ROS) markers have been evaluated. When cells were growing in irradiating conditions at dose rates beyond 4 cGy h^-1, a decreasing of cells and generation numbers with a prolongation of generation time and a change of morphological aspect with rounding-off of cells were observed compared to the control. The 50%-inhibitory dose (ID₅₀) for radiation was estimated at 1568.72 ± 158.45 cGy. The gamma-radiation at dose rates more than 6 cGy h^-1, affected both glyceraldehyde 3-phosphate dehydrogenase and succinate dehydrogenase by inhibiting their activities. All of these effects were more pronounced when cells were irradiated at the dose rate of 20 cGy h^-1 using ⁶⁰Co source. For ROS markers generated by gamma-radiation in T. pyriformis, the results showed an increase of the lipid peroxidation in cells grown in presence of gamma-radiation at dose rates more than 6 cGy h^-1 and an enhancement in catalase and superoxide dismutase activities from the dose rate of 1 cGy h^-1. These encouraging results suggested the use of T. pyriformis as a unicellular model cell to investigate other aspects of the response to ionizing radiation.

Biomarkers of Genotoxicity in Medical Workers Exposed to Low-Dose Ionizing Radiation: Systematic Review and Meta-Analyses

Medical staff represent the largest group of workers occupationally exposed to ionizing radiation (IR). Chronic exposure to low-dose IR may result in DNA damage and genotoxicity associated with increased risk of cancer. This review aims to identify the genotoxicity biomarkers that are the most elevated in IR-exposed vs. unexposed health workers. A systematic review of the literature was performed to retrieve relevant studies with various biomarkers of genotoxicity. Subsequent meta-analyses produced a pooled effect size for several endpoints. The search procedure yielded 65 studies. Chromosome aberrations (CA) and micronuclei (MN) frequencies were significantly different between IR-exposed and unexposed workers (θ_pooled = 3.19, 95% CI 1.46–4.93; and θ_pooled = 1.41, 95% CI 0.97–1.86, for total aberrant cells and MN frequencies, respectively), which was not the case for ring chromosomes and nucleoplasmic bridges. Although less frequently used, stable translocations, sister chromatid exchanges (SCE) and comet assay endpoints were also statistically different between IR-exposed and unexposed workers. This review confirms the relevance of CA and MN as genotoxicity biomarkers that are consistently elevated in IR-exposed vs. unexposed workers. Other endpoints are strong candidates but require further studies to validate their usefulness. The integration of the identified biomarkers in future prospective epidemiological studies is encouraged.

Genetic polymorphisms in XRCC1, OGG1, and XRCC3 DNA repair genes and DNA damage in radiotherapy workers

DNA damage may develop at any dose of ionizing radiation. DNA damage activates pathways that regulate cell growth and division or coordinate its replication and repair. The repair pathways, base excision repair (BER) and single-strand break repair (SSBR), can repair such damages efficiently and maintain genome integrity. Loss of this repair process or alteration of its control will be associated with serious outcomes for cells and individuals. This study aimed to determine the relationship between XRCC1 (Arg194Trp, Arg280His, and Arg399Gln), OGG1 (Ser326Cys), and XRCC3 (Thr241Met) SNPs and DNA damage and to identify high-risk individuals with reduced DNA repair capacity. This case-control study was conducted on 80 subjects; 50 subjects working in Clinical Oncology and Nuclear Medicine Department in Assiut University Hospital along with 30 controls. A total of 1 mL blood samples were collected for Single-Cell Gel Electrophoresis Technique (Comet Assay) for detection of DNA damage in those subjects. A total of 3 mL fresh blood samples were collected and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)-based technique. DNA damage detected by comet test was significantly high in IR-exposed workers than control. Statistically high significant difference was found in exposed subjects versus control subjects regarding the frequencies of the variant alleles of hOGG1³²⁶, XRCC1^{280 & 399}, and XRCC3²⁴¹. The level of DNA damage was not affected by OGG1³²⁶ SNPs when comparing subjects of wild genotype with those of (pooled) variants either in the exposed staff or in the control group while XRCC1^{280, 399} and XRCC3²⁴¹ variant alleles had an influence on the studied DNA damage biomarker. Moreover, genotyping distribution pattern was highly variable in relation to gender. The present study indicated a relationship between DNA damage detected by comet test and single nucleotide polymorphisms in genes coding for DNA certain repair enzymes. Individuals occupationally exposed to low doses of ionizing radiation could be at great risk and more susceptible to the increased DNA damage if they have inherited genetic polymorphism.

Cardiac arrhythmia catheter ablation procedures guided by x-ray imaging: N-acetylcysteine protection against radiation-induced cellular damage (CARAPACE study): study design

PURPOSE

Catheter ablation (CA) procedures are characterized by exposure to ionizing radiations (IR). IR can cause DNA damage and may lead to carcinogenesis if not efficiently repaired. The primary endpoint of this study is to investigate whether intravenous administration of N-acetylcysteine prior to CA procedure may prevent systemic oxidative stress and genomic DNA damage induced by exposure to IR.

METHODS

The "Cardiac Arrhythmia catheter ablation procedures guided by x-Ray imaging: N-Acetylcysteine Protection Against radiation induced Cellular damagE" (CARAPACE) study is a prospective, randomized, single-blinded, parallel-arm monocenter study enrolling 550 consecutive patients undergoing CA at the Arrhythmology Unit of Centro Cardiologico Monzino (CCM). Inclusion criteria are age ≥ 18, indication for CA procedure guided by IR imaging, and written informed consent. IR levels will be measured via fluoroscopy time, effective dose, and dose area product. Glutathione and glutathione disulfide concentrations will be measured, and urinary levels of 8-iso-prostaglandin-F_2α and 8-hydroxy-2-deoxyguanosine will be quantified. The enrolled patients will be randomized 1:1 to the N-acetylcysteine group or to the control group.

RESULTS

We expect that pre-operative administration of N-acetylcysteine will prevent IR-induced systemic oxidative stress. The study will provide data on oxidative DNA damage assessed by urinary 8-hydroxy-2-deoxyguanosine levels and direct evidence of genomic DNA damage in blood cells by comet assay.

CONCLUSION

Catheter ablation procedures can lead to IR exposure and subsequent DNA damage. N-acetylcysteine administration prior to the procedure may prevent them and therefore lead to less possible complications.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT04154982).

Genotoxic risk in health-care professionals occupationally exposed to low doses of ionizing radiation

The purpose of this study was to evaluate the potential influence of occupational ionizing radiation (IR) exposure on health professionals, assessing DNA damage using the comet and micronucleus (MN) assays and analyzing relative risks, correlations, and associated factors between outcomes and socioeconomic and lifestyle factors. Blood and buccal samples were collected from 36 workers, who actively participated in an imaging sector of a hospital, who were either exposed to IR directly or indirectly (9 internal control and 27 exposed), and 27 individuals living in the same city but with no occupational exposure (external control, unexposed/healthy). All radiation dosages performed on the 36 workers were less than 20 mSv/y, not exceeding the effective dose limit for occupational exposure. A questionnaire identified socioeconomic and lifestyle factors associated with the outcomes. The results of the MN assay showed a significant difference between both internal control and the exposed group when compared to the external control. For the comet assay, there were significant differences between the percent of tail DNA of the exposed group and external controls, but no difference was found between the exposed group and internal controls. Relative risk associations were found in time of exposure, hours worked per week, and perceived stress. Correlations were found between the outcomes and age, consumption of alcohol, and frequencies of X-rays during life. Variables that showed to be significant in the adjusted analysis were skin color and recent exposure to radiation. Albeit limited, the findings of this study suggest genotoxicity in both blood and buccal mucosa cells of workers exposed directly or indirectly to IR and that lifestyle and socioeconomic factors are associated and correlated with the risk of developing these outcomes.

Radioprotective efficacy of plastic polymer against the toxicogenomic effects of radiopharmaceutical 18F-FDG on human lymphocytes

BACKGROUND

Healthcare workers occupationally exposed to 18F-FDG cannot wear protective equipment, such as lead aprons, since the interaction between high energy radiation (511 keV) and metal increases the dose of radiation absorption. The objective of this study was to evaluate the shielding efficacy of a plastic polymer against the toxicogenomic effects of ionizing radiation in human lymphocytes, using cytokinesis-block micronucleus assays.

METHODS

Human peripheral blood lymphocytes were isolated from three subjects and cultured under standard conditions. The cultures were exposed to 300 mCi of 18F-FDG at a distance of 10 cm for 10 min, in the absence of shielding or with lead, polymer, and lead + polymer shields.

RESULTS

Lead shielding was found to increase the number of counts detected by Geiger-Müller radiation monitors as a consequence of the photoelectron effect. Conversely, the lead + polymer shield reduced the number of counts. The lead, polymer, and lead + polymer shields significantly reduced the frequency of micronuclei, nucleoplasmic bridges, and nuclear buds induced by ionizing radiation. Regarding cytotoxicity, only the lead + polymer shield re-established the cell cycle at the level observed for the negative control.

CONCLUSIONS

Lead aprons that are internally coated with polymer increased the radiological protection of individuals occupationally exposed to 18F-FDG PET/CT, especially during examinations.

DNA repair and metabolic gene polymorphisms affect genetic damage due to diesel engine exhaust exposure

Diesel engine exhaust (DEE) is a complex mixture of toxic gases, halogenated aromatic hydrocarbons, alkyl polycyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, benzene derivatives, metals and diesel exhaust particles (DEPs) generated from the incomplete combustion of diesel fuel. Many of the compounds in this mixture can cause oxidative damage to DNA and are considered carcinogenic for humans. Further, chronic DEE exposure increases risks of cardiovascular and pulmonary diseases. Despite these pervasive health risks, there is limited and inconsistent information regarding genetic factors conferring susceptibility or resistance to DEE genotoxicity. The present study evaluated the effects of polymorphisms in two base excision repair (BER) genes (OGG1 Ser326Cys and XRCC1 Arg280His), one homologous recombination (HRR) gene (XRCC3 Thr241Met) and two xenobiotic metabolism genes (GSTM1 and GSTT1) on the genotoxicity profiles among 123 mechanics exposed to workplace DEE. Polymorphisms were determined by PCR-RFLP. In comet assay, individuals with the GSTT1 null genotype demonstrated significantly greater % tail DNA in lymphocytes than those with non-null genotype. In contrast, these null individuals exhibited significantly lower frequencies of binucleated (BN) cells and nuclear buds (NBUDs) in buccal cells than non-null individuals. Heterozygous hOGG1 326 individuals (hOGG1 326 Ser/Cys) exhibited higher buccal cell NBUD frequency than hOGG1 326 Ser/Ser individuals. Individuals carrying the XRCC3 241 Met/Met polymorphism also showed significantly higher buccal cell NBUD frequencies than those carrying the XRCC3 241 Thr/Thr polymorphism. We found a high flow of particulate matter with a diameter of < 2.5 μm (PM_2.5) in the workplace. The most abundant metals in DEPs were iron, copper, silicon and manganese as detected by transmission electron microscopy-energy-dispersive X-ray spectroscopy (TEM-EDX). Scanning electron microscopy (SEM-EDS) revealed particles with diameters smaller than PM_2.5, including nanoparticles forming aggregates and agglomerates. Our results demonstrate the genotoxic effects of DEE and the critical influence of genetic susceptibility conferred by DNA repair and metabolic gene polymorphisms that shed light into the understanding of underlying mechanisms.

Genotoxic risk in health-care professionals occupationally exposed to low doses of ionizing radiation

The purpose of this study was to evaluate the potential influence of occupational ionizing radiation (IR) exposure on health professionals, assessing DNA damage using the comet and micronucleus (MN) assays and analyzing relative risks, correlations, and associated factors between outcomes and socioeconomic and lifestyle factors. Blood and buccal samples were collected from 36 workers, who actively participated in an imaging sector of a hospital, who were either exposed to IR directly or indirectly (9 internal control and 27 exposed), and 27 individuals living in the same city but with no occupational exposure (external control, unexposed/healthy). All radiation dosages performed on the 36 workers were less than 20 mSv/y, not exceeding the effective dose limit for occupational exposure. A questionnaire identified socioeconomic and lifestyle factors associated with the outcomes. The results of the MN assay showed a significant difference between both internal control and the exposed group when compared to the external control. For the comet assay, there were significant differences between the percent of tail DNA of the exposed group and external controls, but no difference was found between the exposed group and internal controls. Relative risk associations were found in time of exposure, hours worked per week, and perceived stress. Correlations were found between the outcomes and age, consumption of alcohol, and frequencies of X-rays during life. Variables that showed to be significant in the adjusted analysis were skin color and recent exposure to radiation. Albeit limited, the findings of this study suggest genotoxicity in both blood and buccal mucosa cells of workers exposed directly or indirectly to IR and that lifestyle and socioeconomic factors are associated and correlated with the risk of developing these outcomes.

Antioxidant status and cytogenetic damage in hospital workers occupationally exposed to low dose ionizing radiation

The aim of the present study was to assess the oxidative stress level and chromosomal damage induced by occupational exposure to low dose ionizing radiation (LDIR). Two hundred and eighteen hospital workers occupationally exposed to LDIR were included in this study, along with 118 healthy age- and gender-comparable controls. Occupational dosimetry records were collected over the last year and revealed that the accumulated annual dose for each hospital worker was below the permissible limit of the International Commission on Radiological Protection (ICRP). The individuals' oxidative and antioxidative status were determined by measuring the activities of copper zinc-superoxide dismutase (CuZn-SOD), glutathione peroxidase (GSH-Px), catalase (CAT) enzymes, and the levels of malondialdehyde (MDA) in erythrocytes. The effect of radiation on chromosomal integrity was measured by the frequency of micronuclei (MN) formation using the cytokinesis block technique. Our results showed that the activities of CuZn-SOD and CAT enzymes and MDA levels observed in the hospital workers were higher than those in the controls (p < 0.05). We did not find significant difference in GSH-Px enzyme activity between the two groups (p = 0.247). A higher frequency of MN was found in exposed groups than in the controls [3(1-5) ‰ versus 2(0.75-4) ‰; p<0.001]. The difference was significant for males (p = 0.012), but not females (p = 0.14). Multiple linear regression analysis showed differences in the oxidant activities and MN frequency between hospital workers and controls adjusted for age, gender, smoking status and drinking status. Correlation analysis indicated that the frequency of MN was positively associated with MDA levels (p < 0.05). Altogether, these results support the detrimental effects of chronic low dose radiation in humans, which involves the induction of oxidative stress and chromosomal damage.

Chronic low dose exposure of hospital workers to ionizing radiation leads to increased micronuclei frequency and reduced antioxidants in their peripheral blood lymphocytes

Purpose: The regular low dose occupational exposure to ionizing radiation may induce deleterious health effects, which may be of particular interest to medical radiation workers who daily handle X-ray machines. Human peripheral blood lymphocytes are able to retain the signature of radiation-induced DNA damage, therefore, the present study was undertaken to investigate the DNA damage and antioxidants status in hospital workers occupationally exposed to low doses of X-rays. Materials and methods: The peripheral blood lymphocytes of the occupationally exposed and control groups matched for age, gender, tobacco usage, and alcohol consumption were cultured and micronuclei frequency was determined. Activities of antioxidant enzymes and lipid peroxidation were also estimated in their plasma. Results: The micronuclei frequency in the occupationally exposed group (n = 33), increased significantly (p < .0001) followed by reduced glutathione-s-transferase (p < .01) and catalase (p < .001) activities, and increased lipid peroxidation (p < .05) when compared to the control group (n = 33). Occupational exposure resulted in an effective dose ranging between 3.14 to 144.5 mSv (40.88 ± 39.86mSv) depending on the employment duration of 3-29 years (10.33 ± 7.05 years). A correlation between the micronuclei frequency (p < .05) and catalase activity (p < .05) existed in the occupationally exposed individuals depending on the smoking habit, age, duration of employment, cumulative exposure dose and number of patients handled per day. Conclusions: We have observed that protracted low dose exposure to ionizing radiation is an inevitable occupational hazard leading to persistence of oxidative stress and increased genomic instability in the radiological technicians depending on the time spent with X-rays, cumulative dose received and the number of patients handled daily raising the risk of cancer development.

Cytogenetic status of interventional radiology unit workers occupationally exposed to low-dose ionising radiation: A pilot study

Interventional radiology unit workers represent one of the occupationally most exposed populations to low-dose ionizing radiation. Since there are many uncertainties in research of doses below 100 mSv, this study attempted to evaluate DNA damage levels in chronically exposed personnel. The study group consisted of 24 subjects matched with a control population by the number of participants, age, gender ratio, active smoking status, the period of blood sampling, and residence. Based on regular dosimetry using thermoluminiscent dosimeters, our study group occupationally received a dose of 1.82 ± 3.60 mSv over the last year. The results of the cytokinesis-block micronucleus assay and the comet assay showed a higher nuclear buds frequency (4.09 ± 1.88) and tail length (15.46 ± 1.47 μm) than in the control group (2.96 ± 1.67, 14.05 ± 1.36 μm, respectively). Differences in other descriptors from both tests did not reach statistical significance. Further investigations are needed to develop algorithms for improving personal dosimetry and those that would engage larger biomonitoring study groups.

Health Effects from Occupational Radiation Exposure among Fluoroscopy-Guided Interventional Medical Workers: A Systematic Review

A systematic review was conducted to provide an overview of the health effects of occupational radiation exposure from interventional fluoroscopy procedures on medical radiation workers. Among the 34 studies that met the inclusion criteria, most studies were cross-sectional (76%) and published after 2011 (65%) in a handful of countries. Although diverse outcomes were reported, most studies focused on cataracts. Radiation health effects were rarely assessed by risk per unit dose. Interventional radiation medical workers represent a small subset of the population studied worldwide. Further epidemiologic studies should be conducted to evaluate health outcomes among interventional radiation medical workers.

Single nucleotide polymorphisms in DNA glycosylases: From function to disease

Oxidative stress is associated with a growing number of diseases that span from cancer to neurodegeneration. Most oxidatively induced DNA base lesions are repaired by the base excision repair (BER) pathway which involves the action of various DNA glycosylases. There are numerous genome wide studies attempting to associate single-nucleotide polymorphisms (SNPs) with predispositions to various types of disease; often, these common variants do not have significant alterations in their biochemical function and do not exhibit a convincing phenotype. Nevertheless several lines of evidence indicate that SNPs in DNA repair genes may modulate DNA repair capacity and contribute to risk of disease. This overview provides a convincing picture that SNPs of DNA glycosylases that remove oxidatively generated DNA lesions are susceptibility factors for a wide disease spectrum that includes besides cancer (particularly lung, breast and gastrointestinal tract), cochlear/ocular disorders, myocardial infarction and neurodegenerative disorders which can be all grouped under the umbrella of oxidative stress-related pathologies.

Arsenic and subclinical vascular damage in a sample of Italian young adults: a cross-sectional analysis

Exposure to arsenic (As) increases cardiovascular risk. The purpose of this study was to evaluate the relationship between As and intima-media thickness (IMT) in the common carotid artery and common genetic variants in genes implicated in As metabolism (ASIIIMT Met287Thr, GSTT1+/-, and GSTM1+/-) and DNA repair (hOGG1 Ser326Cys and XRCC1 Arg399Ser). Two hundred and fourteen healthy volunteers, age 20-46, were recruited in four zones polluted by As. Urine samples were tested for total As, inorganic As (iAs), monomethylarsinic (MMA), and dimethylarsinic acid (DMA). Primary and secondary methylation index (PMI, SMI) were computed as MMA/iAs and DMA/MMA. Common carotid artery scans were obtained by high-resolution ultrasound. There was no correlation between IMT and total As, iAs, iAs + MMA + DMA, PMI, or SMI. However, the increase of IMT with age was higher than that observed in the healthy population, both in males (6.25 vs. 5.20 μm/year) and, to a lesser extent, in females (5.05 vs. 4.97 μm/year). After correction for age and gender, subjects with a high urinary As level (≥3.86 μg/L) and carriers of the GSTT1-positive (+) genotype also had higher IMT than those with a low urinary level and the GSTT1-null (-) genotype (0.56 [0.48-0.64] vs. 0.53 [0.44-0.62] mm, p = 0.010). The analysis hints at faster vascular aging as compared to the healthy population. Our findings also suggested that GSTT1 and hOGG1 gene polymorphisms might play an important role in the individual risk of As-induced carotid atherosclerosis.

Reduction of Fluoroscopy Time and Radiation Dosage During Catheter Ablation for Atrial Fibrillation

Radiofrequency catheter ablation has become the treatment of choice for atrial fibrillation (AF) that does not respond to antiarrhythmic drug therapy. During the procedure, fluoroscopy imaging is still considered essential to visualise catheters in real-time. However, radiation is often ignored by physicians since it is invisible and the long-term risks are underestimated. In this respect, it must be emphasised that radiation exposure has various potentially harmful effects, such as acute skin injury, malignancies and genetic disease, both to patients and physicians. For this reason, every electrophysiologist should be aware of the problem and should learn how to decrease radiation exposure by both changing the setting of the system and using complementary imaging technologies. In this review, we aim to discuss the basics of X-ray exposure and suggest practical instructions for how to reduce radiation dosage during AF ablation procedures.

Arsenic exposure, genetic susceptibility and leukocyte telomere length in an Italian young adult population

Arsenic-induced health effects may be associated with critically shortened telomeres. However, few data are available on the effects of arsenic exposure on telomere length. The aim of this study was to investigate the effects of chronic arsenic exposure on leukocyte telomere length (LTL) as well as the contribution of common polymorphisms in genes implicated in arsenic metabolism (GSTT1 and GSTM1) and DNA repair (hOGG1 and XRCC1). A group of 241 healthy subjects was enrolled from four areas of Italy known to be affected by natural or anthropogenic arsenic pollution. Urine samples were tested for inorganic As (iAs), monomethylarsinic (MMA) and dimethylarsinic acid (DMA). LTL was evaluated by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Genotyping was carried out by PCR-RFLP on leukocyte DNA. In multiple linear regression analysis, LTL was significantly and inversely correlated with age (β = -0.231, P = 0.006) and showed a certain trend toward significance with iAs urinary concentration (log10 iAs, β = -0.106, P = 0.08). The genotype distribution showed significant associations between GSTT1 and the As concentration (log10 iAs, P = 0.01) and metabolite patterns (log10 DMA, P = 0.05) in the urine. However, GST genes did not interact with arsenic exposure in the modulation of LTL. Conversely, the combined presence of a higher level of iAs + MMA + DMA ≥ 19.3 μg/l (F = 6.0, P interaction = 0.01), Asi ≥ 3.86 (F = 3.9, P interaction = 0.04) μg/l, iAs + MMA + DMA ≥ 15 μg/l (F = 4.2, P interaction = 0.04) and hOGG1 Cys allele was associated with a significantly lower LTL. An interaction between XRCC1 Arg399Gln and arsenic exposure was also observed (all P interaction = 0.04). These findings suggest that telomere shortening may represent a mechanism that contributes to arsenic-related disease. The interaction of hOGG1 and XRCC1 DNA repair polymorphisms and exposure enhances telomeric DNA damage. Future studies are warranted to understand better the epidemiologic impact of arsenic on telomere function as well as to identify the subgroups of exposed subjects who need better health surveillance.

Redox status in workers occupationally exposed to long-term low levels of ionizing radiation: A pilot study

OBJECTIVES

Reactive oxygen species (ROS), including superoxide (O2(•-)), play an important role in the biological effects of ionizing radiation. The human body has developed different antioxidant systems to defend against excessive levels of ROS. The aim of the present study is to investigate the redox status changes in the blood of radiologic technologists and compare these changes to control individuals.

METHODS

We enrolled 60 medical workers: 20 occupationally exposed to ionizing radiation (all radiologic technologists), divided in three subgroups: conventional radiography (CR), computerized tomography (CT), and interventional radiography (IR) and 40 age- and gender-matched unexposed controls. Levels of O2(•-) and malondialdehyde (MDA) in blood were measured as an index of redox status, as were the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase. Redox status was also assessed by measuring levels of reduced and oxidized glutathione (GSH, GSSG, respectively).

RESULTS

Levels of O2(•-) and MDA, and SOD activity in the blood of IR and CT-exposed subjects were significantly higher than both the CR-exposed subjects and control individuals. However, there were no statistically significant differences in the levels of catalase, GSH and ratio of GSH/GSSG between exposed workers and control individuals.

DISCUSSION

This study suggests that healthcare workers in CT and IR occupationally exposed to radiation have an elevated circulating redox status as compared to unexposed individuals.

Subclinical carotid atherosclerosis and early vascular aging from long-term low-dose ionizing radiation exposure: a genetic, telomere, and vascular ultrasound study in cardiac catheterization laboratory staff

OBJECTIVES

This study sought to assess the association between long-term radiation exposure in the catheterization laboratory (cath lab) and early signs of subclinical atherosclerosis.

BACKGROUND

There is growing evidence of an excess risk of cardiovascular disease at low-dose levels of ionizing radiation exposure.

METHODS

Left and right carotid intima-media thickness (CIMT) was measured in 223 cath lab personnel (141 male; age, 45 ± 8 years) and 222 unexposed subjects (113 male; age, 44±10 years). Leukocyte telomere length (LTL) was evaluated by quantitative reverse transcriptase polymerase chain reaction. The DNA repair gene XRCC3 Thr241Met polymorphism was also analyzed to explore the possible interaction with radiation exposure. The occupational radiological risk score (ORRS) was computed for each subject on the basis of the length of employment, individual caseload, and proximity to the radiation source. A complete lifetime effective dose (mSv) was recorded for 57 workers.

RESULTS

Left, right, and averaged CIMTs were significantly increased in high-exposure workers compared with both control subjects and low-exposure workers (all p values<0.04). On the left side, but not on the right, there was a significant correlation between CIMT and ORRS (p=0.001) as well as lifetime dose (p=0.006). LTL was significantly reduced in exposed workers compared with control subjects (p=0.008). There was a significant correlation between LTL and both ORRS (p=0.002) and lifetime dose (p=0.03). The XRCC3 Met241 allele presented a significant interaction with high exposure for right side (pinteraction=0.002), left side (pinteraction<0.0001), and averaged (pinteraction<0.0001) CIMTs.

CONCLUSIONS

Long-term radiation exposure in a cath lab may be associated with increased subclinical CIMT and telomere length shortening, suggesting evidence of accelerated vascular aging and early atherosclerosis.

Correlation between selected XRCC2, XRCC3 and RAD51 gene polymorphisms and primary breast cancer in women in Pakistan

Genetic polymorphisms in homologous recombination repair genes cause an abnormal development of cancerous cells. In the present study we evaluated the possibility of breast cancer association with single nucleotide polymorphisms of RAD51, XRCC2 and XRCC3 genes. Polymorphisms selected in this study were RAD51 135G/C, XRCC2 Arg188His; and XRCC3 Thr241Met. Each polymorphism was genotyped using Polymerase chain reaction-restriction fragment length polymorphism in study cohort of 306 females (156 breast cancer patients and 150 controls). We observed that heterozygous variant genotype (GC) of RAD51 135 G/C polymorphism was associated with a significantly (OR=2.70; 95%CI (0.63-1.79); p<0.03) increased risk of breast cancer. In case of the XRCC3 gene we observed that frequency of heterozygous (OR=2.88; 95%CI (1.02-8.14); p<0.02) and homozygous (OR=1.46; 95%CI (0.89-2.40); p<0.04) genotype of Thr241Met polymorphism were significantly higher in breast cancer patients. For the Arg188His polymorphism of XRCC2, ~2fold increase in breast cancer risk (OR=1.6, 95%CI = 0.73-3.50) was associated with GA genotype with a p value for trend of 0.03. Our results suggest that the 135G/C polymorphism of the RAD51, Thr241Met polymorphism of XRCC3 and Arg188His polymorphism of XRCC2 can be independent markers of breast cancer risk in Pakistan.

The Growing Culture Of A Minimally Fluoroscopic Approach In Electrophysiology Lab

Most of interventional procedures in cardiology are carried out under fluoroscopic imaging guidance. Besides other peri-interventional risks, radiation exposure should be considered for its stochastic (inducing malignancy) and deterministic effects on health (tissue reactions like erythema, hair loss and cataracts). In this article we analized the radiation risk from cardiovascular imaging to both patients and medical staff and discusses how customize the X-ray system and how to implement shielding measures in the cath lab. Finally, we reviewed the most recent developments and the latest findings in catheter navigation and 3D electronatomical mapping systems that may help to reduce patient and operator exposure.

Human AP endonuclease 1: a potential marker for the prediction of environmental carcinogenesis risk

Human apurinic/apyrimidinic endonuclease 1 (APE1) functions mainly in DNA repair as an enzyme removing AP sites and in redox signaling as a coactivator of various transcription factors. Based on these multifunctions of APE1 within cells, numerous studies have reported that the alteration of APE1 could be a crucial factor in development of human diseases such as cancer and neurodegeneration. In fact, the study on the combination of an individual's genetic make-up with environmental factors (gene-environment interaction) is of great importance to understand the development of diseases, especially lethal diseases including cancer. Recent reports have suggested that the human carcinogenic risk following exposure to environmental toxicants is affected by APE1 alterations in terms of gene-environment interactions. In this review, we initially outline the critical APE1 functions in the various intracellular mechanisms including DNA repair and redox regulation and its roles in human diseases. Several findings demonstrate that the change in expression and activity as well as genetic variability of APE1 caused by environmental chemical (e.g., heavy metals and cigarette smoke) and physical carcinogens (ultraviolet and ionizing radiation) is likely associated with various cancers. These enable us to ultimately suggest APE1 as a vital marker for the prediction of environmental carcinogenesis risk.

Genetic risk score and acute skin toxicity after breast radiation therapy

Genetic predisposition has been shown to affect the severity of skin complications in breast cancer patients after radiotherapy. Limited data exist regarding the use of a genetic risk score (GRS) for predicting risk of tissue radiosensitivity. We evaluated the impact of different single-nucleotide polymorphisms (SNPs) in genes related to DNA repair mechanisms and oxidative stress response combined in a GRS on acute adverse effects induced by breast radiation therapy (RT). Skin toxicity was scored according to the Radiation Therapy Oncology Group (RTOG) criteria in 59 breast cancer patients who received RT. After genotyping, a multilocus GRS was constructed by summing the number of risk alleles. The hazard ratio (HR) for GSTM1 was 2.4 (95% confidence intervals [CI]=1.1-5.3, p=0.04). The other polymorphisms were associated to an increased adverse radiosensitivity, although they did not reach statistical significance. GRS predicted roughly 40% risk for acute skin toxicity per risk allele (HR 1.37, 95% CI=1.1-1.76, p<0.01). Patients in the top tertile had a fivefold higher risk of skin reaction (HR 5.1, 95% CI=1.2-22.8, p=0.03). Our findings demonstrate that the joint effect of SNPs from oxidative stress and DNA damage repair genes may be a promising approach to identify patients with a high risk of skin reaction after breast RT.

Practical ways to reduce radiation dose for patients and staff during device implantations and electrophysiological procedures

Despite the advent of non-fluoroscopic technology, fluoroscopy remains the cornerstone of imaging in most interventional electrophysiological procedures, from diagnostic studies over ablation interventions to device implantation. Moreover, many patients receive additional X-ray imaging, such as cardiac computed tomography and others. More and more complex procedures have the risk to increase the radiation exposure, both for the patients and the operators. The professional lifetime attributable excess cancer risk may be around 1 in 100 for the operators, the same as for a patient undergoing repetitive complex procedures. Moreover, recent reports have also hinted at an excess risk of brain tumours among interventional cardiologists. Apart from evaluating the need for and justifying the use of radiation to assist their procedures, physicians have to continuously explore ways to reduce the radiation exposure. After an introduction on how to quantify the radiation exposure and defining its current magnitude in electrophysiology compared with the other sources of radiation, this position paper wants to offer some very practical advice on how to reduce exposure to patients and staff. The text describes how customization of the X-ray system, workflow adaptations, and shielding measures can be implemented in the cath lab. The potential and the pitfalls of different non-fluoroscopic guiding technologies are discussed. Finally, we suggest further improvements that can be implemented by both the physicians and the industry in the future. We are confident that these suggestions are able to reduce patient and operator exposure by more than an order of magnitude, and therefore think that these recommendations are worth reading and implementing by any electrophysiological operator in the field.

Evaluation of DNA damage in COPD patients and its correlation with polymorphisms in repair genes

BACKGROUND

We investigated a potential link between genetic polymorphisms in genes XRCC1 (Arg399Gln), OGG1 (Ser326Cys), XRCC3 (Thr241Met), and XRCC4 (Ile401Thr) with the level of DNA damage and repair, accessed by comet and micronucleus test, in 51 COPD patients and 51 controls.

METHODS

Peripheral blood was used to perform the alkaline and neutral comet assay; and genetic polymorphisms by PCR/RFLP. To assess the susceptibility to exogenous DNA damage, the cells were treated with methyl methanesulphonate for 1-h or 3-h. After 3-h treatment the % residual damage was calculated assuming the value of 1-h treatment as 100%. The cytogenetic damage was evaluated by buccal micronucleus cytome assay (BMCyt).

RESULTS

COPD patients with the risk allele XRCC1 (Arg399Gln) and XRCC3 (Thr241Met) showed higher DNA damage by comet assay. The residual damage was higher for COPD with risk allele in the four genes. In COPD patients was showed negative correlation between BMCyt (binucleated, nuclear bud, condensed chromatin and karyorrhexic cells) with pulmonary function and some variant genotypes.

CONCLUSION

Our results suggest a possible association between variant genotypes in XRCC1 (Arg399Gln), OGG1 (Ser326Cys), XRCC3 (Thr241Met), and XRCC4 (Ile401Thr), DNA damage and progression of COPD.

Association of XRCC1, XRCC3, and XPD genetic polymorphism with an increased risk of hepatocellular carcinoma because of the hepatitis B and C virus

OBJECTIVE

The south-east Asian and sub-Saharan African populations are the most susceptible to hepatocellular carcinoma (HCC). We aimed to establish whether XRCC1, XRCC3, and XPD are associated with liver cancer in Pakistan and to examine the interaction of hepatitis B virus (HBV) or hepatitis C virus (HCV) with repaired genes in the occurrence of liver cancer.

MATERIALS AND METHODS

We enrolled 74 healthy individuals, 75 had either HBV or HCV, and 50 were HCC patients. The characteristic information of all the study participants were collected through a standard interviewer-administered questionnaire. The PCR-RFLP was used to identify the genotype of the patients.

RESULTS

The results of our study indicated that the patients infected with HBV or HCV had a four or three-fold greater risk of developing liver cancer. Patients older than 55 years of age had a significantly higher risk of developing cancer compared with younger patients. The homozygous wild types Arg/Arg for 280 and Thr/Thr for 241 were more frequent in the controls than in the cases. The allelic frequency of mutant 280His and 399Gln was more pronounced among HCC cases than the controls or the HBV-infected patients.

CONCLUSION

The frequency of the XPD gene in the controls was in Hardy-Weinberg equilibrium, indicating that the gene played a protective role in the Pakistani population. XRCC1 or XRCC3 was associated with liver cancer in the Pakistani population; however, the XPD gene played a vital role in the repair of DNA damage.

Association between genetic variants of DNA repair genes and coronary artery disease

Polymorphisms in DNA repair genes may be associated with differences in the repair efficiency of DNA damage and may influence an individual's risk of atherosclerosis. Genetic research on coronary artery disease (CAD) has traditionally focused on investigation aimed at identifying disease-susceptibility genes. The aim of this study was to investigate the relationship between AP-endonuclease-1 (Asp148Glu), XRCC1 (Arg399Gln), XRCC3 (Thr241Met), XPD (Lys751Gln), XPG (Asp1104His), and hOGG1 (Ser326Cys), gene polymorphisms and the risk of developing CAD in a Turkish population. The study population consisted of 197 patients with acute coronary syndrome (ACS) with chronic CAD and 135 healthy subjects' age and sex matched. Gene polymorphisms were determined by the polymerase chain reaction-restriction fragment length polymorphism method. We demonstrated for the first time, a positive association of XRCC3 and hOGG1 DNA repair gene variants with CAD risk. XRCC3 Thr/Thr genotype and Thr allele frequencies were significantly increased in ACS and chronic CAD patients compared with the control group (p<0.05). It was also observed that there is a protective role of XRCC3 Met alleles against both ACS and chronic CAD (p<0.05). hOGG1 Cys alleles were found significantly higher in ACS patients than in the control group and carriers of the Cys allele had a 1.7-fold increased risk for ACS. In addition, we confirmed the association of XRCC3 Thr241Met and hOGG1 Ser326Cys gene variants with CAD by haplotype analysis. We found that CAD risk is associated with XRCC3 Thr: hOGG1 Cys haplotype, whereas XRCC3 Met: hOGG1 Ser haplotype was found to be protective against the disease. The preliminary results suggested that XRCC3 and hOGG1 genetic variants may be risk factors by affecting the enzyme's function that may lead to development of CAD.

Significant reduction of fluoroscopy in pediatric catheter ablation procedures: long-term experience from a single center

BACKGROUND

Traditionally fluoroscopy has been used for navigation of catheters during electrophysiological procedures. Recent advances in electroanatomic mapping technologies resulted in a decrease and even in elimination of fluoroscopy exposure during these procedures.

METHODS

Electrophysiological procedures were performed with the use EnSite NavX™ or Velocity™ (St. Jude Medical, St. Paul, MN, USA) systems. Following construction of the right atrial geometry, other relevant geometries were formed (right ventricle, coronary sinus, or left atrium). Fluoroscopy was used in patients with complex congenital heart disease, in younger children, and during transseptal punctures. Cryoablation or radiofrequency was used for catheter ablation.

RESULTS

A total of 305 patients underwent catheter ablation for various supraventricular and ventricular tachyarrhythmia substrates using EnSite system guidance. No fluoroscopy was used in 191 (63%) of these cases. The mean fluoroscopy time in the rest of the procedures was 13.9 ± 11.6 minutes (0.2-60 minutes). The mean procedure time was 184 ± 71 minutes. No complications were noted except for temporary diaphragmatic paralysis in one patient and temporary AV block in another patient following cryoablation. Acute success rate in achieving complete elimination of arrhythmia substrates was 95% (290/305). The recurrence rate was (31/271) 11.4% at a mean follow-up time of 42 ± 23 months.

CONCLUSIONS

Fluoroscopy can be significantly decreased or even eliminated in the majority of catheter ablation procedures. Long-term results demonstrate that this can be done efficiently and safely.

An interethnic variability and a functional prediction of DNA repair gene polymorphisms: the example of XRCC3 (p.Thr241>Met) and XPD (p.Lys751>Gln) in a healthy Tunisian population

Genetic polymorphisms in DNA repair genes might influence the repair activities of the enzymes predisposing individuals to cancer risk. Owing to the presence of these genetic variants, interethnic differences in DNA repair capacity have been observed in various populations. The present study was undertaken to determine the allele and genotype frequencies of two common non-synonymous SNPs, XRCC3 p.Thr241>Met (C > T, rs861539) and XPD p.Lys751>Gln (T > G, rs13181) in a healthy Tunisian population and to compare them with HapMap ( http://www.hapmap.org/ ) populations. Also, we predicted their eventual functional effect based on bioinformatics tools. The genotypes of 154 healthy and unrelated individuals were determined by PCR-RFLP procedure. Our findings showed a close relatedness with Caucasians from European ancestry which might be explained by the strategic geographic location of Tunisia in the Mediterranean, thus allowing exchanges with Europeans countries. The in silico predictions showed that p.Thr241>Met substitution in XRCC3 protein was predicted as possibly damaging, indicating that it is likely to have functional consequences as well. To the best of our knowledge, this is the first study in this regard in Tunisia. So, these data could provide baseline database and help us to explore the relationship of XRCC3 and XPD polymorphisms with both cancer risk and DNA repair variability in our population.

The micronucleus assay as a biological dosimeter in hospital workers exposed to low doses of ionizing radiation

The health risk associated with low levels of ionizing radiation is still a matter of debate. A number of factors, such as non-target effects, adaptive responses and low-dose hypersensitivity, affect the long-term outcome of low-dose exposures. Cytogenetic bio-dosimetry provides a measure of the absorbed dose, taking into account the individual radiation sensitivity. The aim of the present study is to evaluate the value of the micronucleus (MN) test as a bio-dosimeter in hospital workers exposed to low doses of ionizing radiation. Blood samples were obtained from 30 subjects selected among workers exposed to X- and gamma-radiation, and 30 controls matched for sex, age and smoking from the same hospital. Micronucleus frequencies were analyzed by use of the cytokinesis-block method. The MN frequency was compared among the groups considering the confounding factors and the length of employment. No increase in the number of bi-nucleated cells with MN (BNMN), but a significant increase in the number of mono-nucleated cells with micronuclei (MOMN) was observed in exposed subjects compared with the controls. The relationship between MN frequency and accumulated dose (mSv) was evaluated. The length of employment did not affect the extent of MN frequency, but an increase of BNMN and MOMN cells was observed based on the accumulated radiation dose. Our study shows the sensitivity of the MN test in the detection of cytogenetic effects of cumulative exposure levels, suggesting the potential usefulness of this assay in providing a biological index in medical surveillance programs.

Variation in DNA repair gene XRCC3 affects susceptibility to astrocytomas and glioblastomas

The gene XRCC3 (X-ray cross complementing group 3) has the task of repairing damage that occurs when there is recombination between homologous chromosomes. Repair of recombination between homologous chromosomes plays an important role in maintaining genome integrity, although it is known that double-strand breaks are the main inducers of chromosomal aberrations. Changes in the XRCC3 protein lead to an increase in errors in chromosome segregation due to defects in centrosomes, resulting in aneuploidy and other chromosomal aberrations, such as small increases in telomeres. We examined XRCC3 Thr241Met polymorphism using PCR-RFLP in 80 astrocytoma and glioblastoma samples. The individuals of the control group (N = 100) were selected from the general population of the São Paulo State. Odds ratio and 95%CI were calculated using a logistic regression model. Patients who had the allele Met of the XRCC3 Thr241Met polymorphism had a significantly increased risk of tumor development (odds ratio = 3.13; 95% confidence interval = 1.50-6.50). There were no significant differences in overall survival of patients. We suggest that XRCC3 Thr241Met polymorphism is involved in susceptibility for developing astrocytomas and glioblastomas.

Initial experience on the application of 320-row CT angiography with low-dose prospective ECG-triggered in children with congenital heart disease

To investigate the clinical significance of the application of 320-row CT angiography with low-dose prospective ECG-triggered target scanning in children with complex congenital heart disease (CHD), and to compare with the results from transthoracic echocardiography (TTE). 22 patients (male 12 cases, female 10 cases, average age: 18 months, range: 14 days-9 years, average weight: 13 kg) received an examination through 320-row CT angiography with low-dose prospective ECG-triggered volume target scan mode and transthoracic echocardiography. The center of phase window for data collection in this study was set to 40% of the R-R interval. Of these, 18 patients received surgery and 4 patients received conventional cardiac angiography (CCA). The diagnostic accuracy of 320-row CTA was calculated according to the examination results from surgical and/or cardiac angiography. The overall quality score for CTA images was divided into five levels. The results were compared with the research data of radiation doses obtained from patients with congenital heart disease who had received CT angiography. Complex congenital heart disease was confirmed by surgical or CCA in each of 22 patients, with 42 cases of large vascular malformations outside the heart cavity, and 26 of intracardiac malformations. The diagnostic accuracy of 320-row CT angiography and transthoracic echocardiography for large vascular malformation outside the heart cavity was 95.2 and 80.9%, respectively; for intracardiac malformation the accuracy was 88.5 and 100.0%, respectively. There was significant difference between 320-row CT and transthoracic echocardiography in the diagnosis of large vascular malformation outside the heart cavity (P < 0.05) with better results in 320-row CT, and no significant difference was found in the diagnosis of intracardiac malformation (P > 0.05). The average subjective image quality score was 4.4 ± 0.7 points. The average effective dose was 0.42 ± 0.08 mSv. 320-row CT enables direct visualization of the vascular configuration and shape of the aorta, pulmonary artery, and other large vessels to diagnose extracardiac vascular malformations. Combined with transthoracic echocardiography, 320-row CT is a promising technology that may be able to replace catheter based angiography to evaluate congenital cardiovascular malformations.

The radiation issue in cardiology: the time for action is now

The "radiation issue" is the need to consider possible deterministic effects (e.g., skin injuries) and long-term cancer risks due to ionizing radiation in the risk-benefit assessment of diagnostic or therapeutic testing. Although there are currently no data showing that high-dose medical studies have actually increased the incidence of cancer, the "linear-no threshold" model in radioprotection assumes that no safe dose exists; all doses add up in determining cancer risks; and the risk increases linearly with increasing radiation dose. The possibility of deterministic effects should also be considered when skin or lens doses may be over the threshold. Cardiologists have a special mission to avoid unjustified or non-optimized use of radiation, since they are responsible for 45% of the entire cumulative effective dose of 3.0 mSv (similar to the radiological risk of 150 chest x-rays) per head per year to the US population from all medical sources except radiotherapy. In addition, interventional cardiologists have an exposure per head per year two to three times higher than that of radiologists. The most active and experienced interventional cardiologists in high volume cath labs have an annual exposure equivalent to around 5 mSv per head and a professional lifetime attributable to excess cancer risk on the order of magnitude of 1 in 100. Cardiologists are the contemporary radiologists but sometimes imperfectly aware of the radiological dose of the examination they prescribe or practice, which can range from the equivalent of 1-60 mSv around a reference dose average of 10-15 mSv for a percutaneous coronary intervention, a cardiac radiofrequency ablation, a multi-detector coronary angiography, or a myocardial perfusion imaging scintigraphy. A good cardiologist cannot be afraid of life-saving radiation, but must be afraid of radiation unawareness and negligence.

Use of 320-detector computed tomographic angiography for infants and young children with congenital heart disease

Pediatric patients with complex congenital heart disease (CHD) face a lifetime of treatment with interventional therapeutic and palliative procedures. Echocardiography remains the mainstay for noninvasive imaging of congenital heart lesions. This often is supplemented with diagnostic cardiac catheterization for additional anatomic and physiologic characterization. However, recent technological improvements in computed tomography (CT) and magnetic resonance imaging (MRI) have led to an increased focus on the use of these techniques given their better safety profile. This study aimed to review the authors' experience with a 320-slice multidetector CT scanner in the evaluation of CHD in children. This retrospective case study investigated 22 infants and young children with a provisional diagnosis of CHD. Their anatomic evaluation was performed using a 320-slice Aquilon ONE CT scanner. Of these 22 patients, 14 were examined without cardiac gating. This was subsequently modified to a prospective gated, targeted protocol to decrease the radiation dose. The images were interpreted by an experienced radiologist and a pediatric cardiologist. Continuous variables were expressed as mean and standard deviation or range, and the two imaging protocols were compared. A comparison of exposure rates with those from other pediatric studies that had used the 64-slice CT angiography also was performed. For the first group of patients, with nongated CT examinations, the mean effective whole-body radiation dose was 1.8 ± 0.71 millisieverts (mSv) (range, 0.96-3.2 mSv). For the second group, the mean was 0.8 ± 0.39 mSv (range, 0.4-1.5 mSv). Although the radiation dose was reduced dramatically, clinicians must be vigilant about the cumulative risk of radiation exposure.

Health risk and biological effects of cardiac ionising imaging: from epidemiology to genes

Cardiac diagnostic or therapeutic testing is an essential tool for diagnosis and treatment of cardiovascular disease, but it also involves considerable exposure to ionizing radiation. Every exposure produces a corresponding increase in cancer risk, and risks are highest for radiation exposure during infancy and adolescence. Recent studies on chromosomal biomarkers corroborate the current radioprotection assumption showing that even modest radiation load due to cardiac catheter-based fluoroscopic procedures can damage the DNA of the cell. In this article, we review the biological and clinical risks of cardiac imaging employing ionizing radiation. We also discuss the perspectives offered by the use of molecular biomarkers in order to better assess the long-term development of health effects.