Nicoletta Botto

Cancer risk from professional exposure in staff working in cardiac catheterization laboratory: Insights from the National Research Council's Biological Effects of Ionizing Radiation VII Report

BACKGROUND Occupational doses from fluoroscopy-guided interventional procedures are the highest ones registered among medical staff using x-rays. The aim of the present study was to evaluate the order of magnitude of cancer risk caused by professional radiation exposure in modern invasive cardiology practice. METHODS From the dosimetric Tuscany Health Physics data bank of 2006, we selected dosimetric data of the 26 (7 women, 19 men; age 46 +/- 9 years) workers of the cardiovascular catheterization laboratory with effective dose >2 mSv. Effective dose (E) was expressed in milliSievert, calculated from personal dose equivalent registered by the thermoluminescent dosimeter, at waist or chest, under the apron, according to the recommendations of National Council of Radiation Protection. Lifetime attributable risk of cancer was estimated using the approach of Biological Effects of Ionizing Radiation 2006 report VII. RESULTS Cardiac catheterization laboratory staff represented 67% of the 6 workers with yearly exposure >6 mSv. Of the 26 workers with 2006 exposure >2 mSv, 15 of them had complete records of at least 10 (up to 25) consecutive years. For these 15 subjects having a more complete lifetime dosimetric history, the median individual effective dose was 46 mSv (interquartile range = 24-64). The median risk of (fatal and nonfatal) cancer (Biological Effects of Ionizing Radiation 2006) was 1 in 192 (interquartile range = 1 in 137-1 in 370). CONCLUSIONS Cumulative professional radiological exposure is associated with a non-negligible Lifetime attributable risk of cancer for the most exposed contemporary cardiac catheterization laboratory staff.

Endothelial nitric oxide synthase gene polymorphisms and risk of coronary artery disease

BACKGROUND Endothelial nitric oxide synthase (eNOS) could be a candidate gene for coronary artery disease (CAD). This study investigated the relationship of the eNOS Glu(298)-->Asp and T(786)-->C polymorphisms with the presence and severity of CAD in the Italian population. METHODS We enrolled 415 unrelated individuals who underwent coronary angiography. The severity of CAD was expressed by means of the Duke score. The eNOS Glu(298)-->Asp and T(786)-->C variants were analyzed by PCR. RESULTS There was significant linkage disequilibrium between the two eNOS polymorphisms (P <0.0001). Both variants were significantly associated with the occurrence and severity of CAD (P = 0.01 and 0.004 for Glu(298)-->Asp and T(786)-->C, respectively). The risk of CAD was increased among individuals homozygous for the C allele of the T(786)-->C polymorphism compared with individuals homozygous for the T allele (odds ratio = 2.5; P <0.01) and was independent of the other common risk factors (P = 0.04). Moreover, individuals with both the Asp/Asp genotype of the Glu(298)-->Asp polymorphism and at least one C allele of the T(786)-->C variant in the promoter region of the eNOS gene had an increased risk of CAD (odds ratio = 4.0; P <0.001) and a significantly higher mean Duke score (26.2 +/- 2.9 vs 45.2 +/- 3.7; P = 0.002) compared with individuals with the TT genotype and the Glu allele. CONCLUSIONS The present study provides evidence that the Glu(298)-->Asp and T(786)-->C polymorphisms of the eNOS gene are associated with the presence and severity of angiographically defined CAD in the Italian population and that those individuals carrying both eNOS variants simultaneously might have a higher risk of developing CAD.

Evidence for enhanced 8-isoprostane plasma levels, as index of oxidative stress in vivo, in patients with coronary artery disease.

Background It is well known that free radicals contribute to endothelial dysfunction and are involved in ageing and in the pathogenesis and development of many cardiovascular diseases, such as atherosclerosis. Measurement of F(2)‐isoprostanes has emerged as probably the most reliable approach to assess oxidative stress status in vivo. In particular, 8‐isoprostane (8‐epiPGF2ct) has been indicated as a marker of antioxidant deficiency and oxidative stress of potential relevance to assess human vascular diseases. Design To provide evidence for enhanced oxidative stress in coronary artery disease (CAD). Methods Plasma levels of 8‐epiPGF2a (EIA, Cayman Chemicals, Ann Arbor, Michigan, USA) were measured in 51 patients (19 females, 32 males, age: 58.7 ± 1.6 years, mean±SEM). Subjects included 13 healthy control subjects (group I), and 38 patients underwent coronary angiography; 11 patients without coronary artery atherosclerotic lesions (group II), and 27 with angiographically proven CAD (group III). Results Plasma levels of 8‐epiPGF2&agr; were 123.2 ± 9.5, 314.6 ± 40 and 389.6 ± 36.2 pg/ml in groups I, II and III respectively (P <0.05 and P < 0.001 groups II and III versus group I, respectively). In group III, 8‐epiPGF2&agr; levels increased with the number of affected vessels (324.4 ± 47.2 and 408.3 ±44.1 pg/ml for one‐ and multi‐vessel disease, P =0.07 and P < 0.001 versus control subjects, respectively). A significant difference in 8‐epiPGF2&agr; levels was observed between patients with and without hypertension (394.2 ± 42.7 and 232.7 ± 25.1 pg/ml, P < 0.01, respectively). In addition, patients with dyslipidaemia presented higher 8‐epiPGF2a levels with respect to non‐dyslipidaemic patients (359.1 ± 35.6 and 240.3 ± 34.3 pg/ml, P <0.05, respectively). A positive relationship was found between age and 8‐epiPGF2&agr; levels (r= 0.42, P < 0.01) in the whole population. Conclusion These findings indicate that elevated levels of plasma 8‐epiPGF2&agr; levels are associated with the extent and the severity of coronary artery disease and with the occurrence of different atherogenic risk factors, supporting the hypothesis that the evaluation of oxidative stress may represent an additional prognostic predictor in such events and a potential target of future therapeutic interventions. Coron Artery Dis 14:213‐218

Elevated levels of oxidative DNA damage in patients with coronary artery disease

BackgroundSomatic DNA damage has been suggested to contribute to the pathogenesis of atherosclerosis. However, little is known about the role of oxidative DNA damage in patients with coronary artery disease (CAD). MethodsIn this study, we used the comet assay to measure oxidative DNA damage (DNA strand breaks and enzyme-sensitive sites) in peripheral blood lymphocytes from 13 patients with angiographically documented CAD and 11 age- and sex-matched control participants. ResultsMean values of DNA strand breaks, oxidized pyrimidines and altered purines were significantly higher in CAD patients than in the control group (11.9 ± 1.4, 18.0 ± 2.7 and 18.1 ± 3.1 compared with 3.3 ± 0.2, 2.7 ± 0.5 and 4.5 ± 1.1; P < 0.0001, P < 0.0001 and P = 0.0009, respectively). Moreover, oxidized purines (for example, 8-oxo-guanine) increased with the number of affected vessels and positively correlated with the extent of CAD measured by means of the number of the coronary lesions (r = 0.76, P = 0.003) and the Duke scoring system (r = 0.66, P = 0.01). Diabetic patients showed higher levels of oxidized pyrimidines (31.3 ± 5.5 compared with 14.1 ± 2.7; P = 0.013), while patients with dyslipidemia had elevated altered purines compared with normal patients (20.4 ± 2.6 compared with 4.9 ± 3.1; P = 0.03). ConclusionsThese data indicate an overall elevation of oxidative DNA damage in CAD patients correlated with the severity of the disease and some atherogenic risk factors, suggesting a possible role of oxidative genetic damage in the pathogenesis of atherosclerosis.

Somatic DNA damage in interventional cardiologists: a case-control study

Interventional cardiologists who work in cardiac catheterization laboratories are exposed to low doses of ionizing radiation that could pose a health hazard. DNA damage is considered to be the main initiating event by which radiation damage to cells results in development of cancer and hereditary disease. The aim of the present study was to assess the effects of chronic low‐dose X‐ray radiation exposure on somatic DNA damage of interventional cardiologists working in highvolume cardiac catheterization laboratories. For this analysis, we used peripheral lymphocytes and the assay for micronuclei (MNs), which is considered to be a reliable biological dosimeter for radiation exposure. We obtained peripheral blood from 62 physicians (mean age±se = 40.6±1.5 years): 31 interventional cardiologists (group I, exposed) and 31 age‐ and sex‐matched clinical cardiologists (group II, nonexposed). Interventional cardiologists showed higher MN values (group I=20.5±1.6 vs. group II=12.8±1.3, P=0.001), although some overlap was apparent in the individual subject analysis. A correlation between years of professional activity and MN frequency value was detectable for interventional cardiologists (r=0.428, P=0.02) but not for clinical cardiologists (r=0.253, P=0.17). The results indicated that, overall, interventional cardiologists working in a high‐volume catheterization laboratory have higher levels of somatic DNA damage when compared with clinical cardiologists working outside the catheterization laboratory. The amount of this damage varies and is only weakly related to the duration of professional exposure, which suggests that a dominant modulation of the underlying genetic substrate by environmental factors has a role in determining the harm in individual physicians.

Endothelial Function and Carotid Intima-Media Thickness in Young Healthy Subjects Among Endothelial Nitric Oxide Synthase Glu298→Asp and T−786→C Polymorphisms

Background and Purpose— To assess the role of the endothelial nitric oxide synthase (eNOS) gene variants as risk factors for early atherosclerosis, we sought to investigate whether two polymorphisms located in the exon 7 (Glu298→Asp) and in the promoter region (T−786→C) of the eNOS gene were associated with functional changes in the endothelium and carotid intima-media thickness (IMT). Methods— Endothelium-dependent flow-mediated brachial artery dilation (FMD), endothelium-independent dilation response to glyceryl trinitrate (GTN), and carotid IMT were assessed by high-resolution ultrasound in 118 healthy young nonsmoker subjects (30.1±0.5 years) genotyped for the eNOS Glu298→Asp and T−786→C polymorphisms. Results— Carotid IMT was inversely related to FMD by univariate analysis (r= −0.28, P= 0.002) and after adjustment for possible confounders in all the subjects (P< 0.01). Asp homozygotes had a significantly lower FMD than Glu carriers (Glu/Glu: 15.0%±1.0%, Glu/Asp: 13.3%±0.7%, Asp/Asp: 9.6%±1.6%; P= 0.005), whereas FMD was unaffected by the T−786→C variant. Neither the Glu298→Asp nor the T−786→C polymorphisms influenced the GTN-mediated dilation. With respect to Glu carriers, Asp/Asp genotype displayed a significantly greater carotid IMT (Glu/Glu: 0.37±0.01 mm, Glu/Asp: 0.35±0.01 mm, Asp/Asp: 0.45±0.03 mm; P= 0.0002) and significant correlations between carotid IMT and FMD (r= −0.48, P= 0.04) and between carotid IMT and resting brachial artery diameter (r= 0.70, P= 0.001). No difference in IMT was found across the T−786→C genotypes. By multivariate regression analysis, Asp/Asp genotype was the only significant and independent predictor of flow-mediated brachial artery dilation (FMD) (P=0.04) and carotid intima-media thickness (IMT) (P=0.006). Conclusions— The eNOS Glu298→Asp polymorphism may be related to early atherogenesis.

Genetic instability and atherosclerosis : Can somatic mutations account for the development of cardiovascular diseases?

Several observations suggest that cancer and atherosclerosis may entail fundamentally common biological mechanisms. The accumulation of lipids and the proliferation of smooth muscle cells (SMCs) are the main histological features of sclerotic plaque formation. The most prominent theory concerning the pathophysiological mechanisms of atherosclerotic plaque formation is the “inflammatory response to injury” hypothesis, which states that SMC proliferation is an inflammation‐fibroproliferative reaction to different insults to the artery wall. However, recent evidence suggests that alterations at the DNA level may contribute significantly to the development of the disease. In accordance with these findings, the “monoclonal” hypothesis of atherosclerosis has been suggested. This hypothesis proposes that atherosclerosis begins as a mutation or viral infection, transforming a single, isolated smooth muscle cell into the progenitor of a proliferative clone, as seen in carcinogenesis. Studies of DNA damage in atherosclerotic tissues are lacking. Biological evidence for the hypothesis that cancer and atherosclerosis may share pathological mechanisms is discussed, emphasizing the need to perform studies investigating the involvement of somatic mutations in heart diseases. Environ. Mol. Mutagen. 35:265–269, 2000

Cumulative patient effective dose in cardiology

Medical radiation from X-rays and nuclear medicine is the largest non-natural (man-made) source of radiation exposure in Western countries. The aim of this study was to assess the individual cumulative effective dose in patients admitted to our cardiology ward. We collected a cumulative radiological history from a structured questionnaire and access to hospital records in 50 consecutive adult patients (36 males; age, 66.7+/-10.8 years) admitted to the Institute of Clinical Physiology in Pisa. The cumulative effective dose was assessed as an indicator of stochastic risk of cancer. We derived the effective dose for each individual examination from the Medical Imaging Guidelines of the European Commission (2001). On average, each patient underwent a median of 36 examinations (interquartile range, 23-46). The median cumulative effective dose was 60.6 mSv. Three types of procedures were responsible for approximately 86% of the total collective effective dose: (i) arteriography and interventional cardiology (12% of examinations, 48% of average dose per patient); (ii) nuclear medicine (5% of examinations, 21% of average dose per patient); and (iii) CT (4% of examinations, 17% of average dose per patient). The median estimated extra risk of cancer was approximately 1 in 200 exposed subjects. In conclusion, the average contemporary cardiological patient is exposed to a significant cumulative effective dose from diagnostic and therapeutic interventions. It is important to log cumulative dose for each patient at the time of each examination. Every effort should be made to justify the indications and to optimize the doses.

Genetic polymorphisms in folate and homocysteine metabolism as risk factors for DNA damage

Epidemiological studies indicated a role for polymorphisms in genes of folate and homocysteine (Hcy) metabolism in the etiology of neurodegenerative disease, congenital defects and coronary artery disease (CAD). This study investigated the effect of several polymorphisms [C677 T, A1298C of methylenetetrahydrofolate reductase (MTHFR) and A66G of methionine synthase reductase (MTRR) genes] on Hcy levels and DNA damage in 68 patients who underwent coronary angiography. Plasma Hcy concentrations were higher in patients with multivessel disease with respect to monovessel disease and no-CAD patients (19.4±2.6 vs 11.6±1.2 and 13.7±1.4 μmol/l, respectively; P=0.03). 677TT patients had higher Hcy levels than those with 677CC or 677CT genotypes (26.2±4.3 vs 13.1±1.4 and 13.0±1.4 μmol/l, respectively; P=0.0006). No significant associations were found between A1298C and A66G polymorphisms and plasma Hcy levels. Among patients with 677CC genotype, 66GG individuals tended to have higher levels of Hcy than 66AA homozygotes (14.5±1.9 vs 8.9±0.7 μmol/l, P=0.06). Multivessel disease patients showed an increased frequency of DNA damage, measured by the micronucleus (MN) frequency, as compared to monovessel disease and no-CAD subjects (12.5±1.1 vs 8.5±0.8 and 8.2±0.9, respectively; P=0.006). The MN were positively correlated with Hcy levels (r=0.33, P=0.006) and were significantly higher in subjects with the 677TT genotype compared with the 677CC or 677CT genotypes (14.4±2.0 vs 8.8±1.2 and 9.5±0.7, respectively; P=0.006). A1298C and A66G polymorphisms had no effect on MN frequency. However, among 677TT patients, 66GG subjects tended to have higher levels of MN than those 66AG and 66AA (18.2±3.6 vs 13.8±4.0 and 10.3±1.7, respectively; P=NS). Our results indicate that genetic instability may be associated with increased risk for multiple Hcy-related diseases.

Prothrombotic Mutations as Risk Factors for Cryptogenic Ischemic Cerebrovascular Events in Young Subjects With Patent Foramen Ovale

Background and Purpose— Patent foramen ovale (PFO) has been identified as a potential risk factor for cerebrovascular ischemia. Procoagulant mutations may increase the risk and impact the choice of appropriate therapy for secondary prevention. We evaluated the prevalence of the 2 most common genetic risk factors for thromboembolism, factor V Leiden (G1691A) and prothrombin G20210A, in young PFO patients who were referred for percutaneous transcatheter closure of their PFO. Methods— Ninety-seven patients (50 men; mean±SD age, 40.9±10.0 years) with first-ever cerebrovascular events before the age of 55 years and 160 age-matched control subjects (69 men; mean±SD age, 40.4±10.5 years) were recruited into the study. Factor V Leiden and prothrombin G20210A mutations were detected by using a multiplex allele-specific polymerase chain reaction assay. Results— The prevalence of subjects carrying at least 1 prothrombotic genotype was significantly higher in the group of PFO patients than in the group of controls (10.3% vs 2.5%; &khgr;2=7.2, P=0.008). Two patients (2.1%) versus 1 control subject (0.6%) and 8 cases (8.2%) versus 3 controls (1.9%) were carriers for factor V Leiden and prothrombin G20210A mutations, respectively. After adjustment for other vascular risk factors, the combination of either factor V Leiden or prothrombin G20210A and PFO was associated with a 4.7-fold (95% CI=1.4 to 16.1; P=0.008) increased risk of cerebral ischemia in young patients. Conclusions— Our results indicate that prothrombotic mutations are important risk factors for cerebral ischemia in young patients with PFO. Screening for thrombotic mutations should be considered in young patients with PFO-related ischemic events.