Cigarette Smoking Induced Oxidative Stress may Impair Endothelial Function and Coronary Blood Flow in Angiographically Normal Coronary Arteries

The association between smoking exposure and endothelial function evaluated using flow-mediated dilation values: a meta-analysis

BACKGROUND

Tobacco use is recognized as a major cause of cardiovascular disease, which is associated with endothelial dysfunction. Endothelial function is evaluated using flow-mediated dilation (FMD), which is a noninvasive method. This meta-analysis aimed to investigate the association between smoking exposure and endothelial function evaluated using FMD values.

METHODS

We searched the PubMed, Embase, Web of Science, and Cochrane Library databases for cohort studies of smokers or passive smokers that used FMD to assess endothelial function. The primary outcome of the study was the change in the rate of FMD. The risk of bias was evaluated using the Cochrane Collaboration tool and Newcastle-Ottawa Scale. Further, the weighted mean difference was used to analyze the continuous data.

RESULTS

Overall, 14 of 1426 articles were included in this study. The results of these articles indicated that smoking is a major cause of endothelial dysfunction and altered FMD; a pooled effect size of - 3.15 was obtained with a 95% confidence interval of (- 3.84, - 2.46). Notably, pregnancy status, Asian ethnicity, or health status did not affect heterogeneity.

CONCLUSIONS

We found that smoking has a significant negative impact on FMD, and measures such as medication or education for smoking cessation may improve endothelial function and reduce the risk of cardiovascular disease.

TRIAL REGISTRATION

The meta-analysis was registered with PROSPERO on April 5th, 2023 (CRD42023414654).

Coronary slow flow and its correlation with reduced left ventricle global longitudinal strain: a case-control study

BACKGROUND

Coronary slow flow (CSF) often links to inflammation and endothelial function disturbance. While conventional ejection fraction measurements fall short in identifying myocardial dysfunction, left ventricular global longitudinal strain (LV GLS) has shown superior efficacy in this regard. Our study aimed to explore subclinical left ventricular systolic dysfunction by assessing LV GLS in patients diagnosed with coronary slow flow (CSF).

METHODS

The study included sixty patients with CSF and sixty control individuals without CSF. Coronary angiography employed the Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) to identify CSF. LV GLS values were evaluated and compared between the two groups.

RESULTS

Significantly reduced LV GLS was evident in the CSF group compared to the control group (- 16.18 ± 1.25 vs. - 19.34 ± 1.33, p < 0.001). A notable correlation (r = 0.492, p < 0.001) between LV GLS and TFC was observed in the CSF group. Multivariate logistic regression analysis highlighted reduced LV-GLS (OR 2.2, 95% CI 1.57-3.09, p < 0.001) and smoking (OR 11.55, 95% CI 3.24-41.2, p < 0.001) as significant predictors for CSF presence. The receiver operating characteristic curve established that an LV GLS value of ≥ - 17.8% accurately predicted the presence of CSF (AUC: 0.958, 95% CI: 0.924-0.991, p < 0.001) with 90% specificity and 91.7% sensitivity.

CONCLUSION

Our study indicates that reduced LV GLS is associated with CSF presence, offering a valuable means to early detect subclinical left ventricular systolic dysfunction in high-risk patients susceptible to heart failure.

TRIAL REGISTRATION

ZU-IRB#7038/12-7-2021 Registered 12 July 2021, email: IRB_123@medicine.zu.edu.eg.

Probability of Cardioembolic vs. Atherothrombotic Pathogenesis of Cryptogenic Strokes in Older Patients

Some clinical, laboratory, ECG, and echocardiographic parameters could provide useful indications to assess the probability of cardioembolism or atherothrombosis in cryptogenic strokes. We retrospectively examined 290 patients with ischemic stroke aged ≥60 years, divided into 3 groups: strokes originating from large artery atherothrombosis (n = 92), cardioembolic strokes caused by paroxysmal atrial fibrillation (n = 88) and cryptogenic strokes (n = 110). In addition to echocardiographic and routine clinical-laboratory variables, neutrophil:lymphocyte ratio, red blood cell distribution width, mean platelet volume, P wave and PR interval duration and biphasic inferior P waves, both on admission and after 7 to 10 days, were also considered. By multiple logistic regression, cardioembolic strokes were compared with large artery atherothrombosis strokes, and beta coefficients were rounded to produce a scoring system. Late PR interval ≥188 ms, left atrium ≥4 cm, left ventricular end-diastolic volume <65 ml, and posterior circulation syndrome were associated with paroxysmal atrial fibrillation (positive scores). In contrast, male gender, hypercholesterolemia, and initial platelet count ≥290 × 10⁹/L were associated with atherothrombosis of large arteries (negative scores). The algebraic sum of these scores produced values indicative of cardioembolism if >0 (positive predictive value 89.1%), or of atherothrombosis, if ≤0 (positive predictive value 72.5%). The area under the receiver operating characteristic curve was 0.85. Among cryptogenic strokes, 41.5% had a score >0 (probable atrial fibrillation) and 58.5% had a score ≤0 (possible atherothrombosis). In conclusion, a scoring system based on electrocardiogram, laboratory, clinical and echocardiographic parameters can provide useful guidance for further investigations and secondary prevention in older patients with cryptogenic stroke.

Tobacco smoking and vascular biology and function: evidence from human studies

Tobacco cigarette smoking is among the most complex and least understood health risk factors. A deeper insight into the pathophysiological actions of smoking exposure is of special importance as smoking is a major cause of chronic non-communicable diseases, in particular of cardiovascular disease as well as risk factors such as atherosclerosis and arterial hypertension. It is well known that smoking exerts its negative effects on cardiovascular health through various interdependent pathophysiological actions including hemodynamic and autonomic alterations, oxidative stress, inflammation, endothelial dysfunction, thrombosis, and hyperlipidemia. Importantly, impaired vascular endothelial function is acknowledged as an early key event in the initiation and progression of smoking-induced atherosclerosis. Increasing evidence from human studies indicates that cigarette smoke exposure associates with a pathological state of the vascular endothelium mainly characterized by reduced vascular nitric oxide bioavailability due to increased vascular superoxide production. In the present overview, we provide compact evidence on the effects of tobacco cigarette smoke exposure on vascular biology and function in humans centered on main drivers of adverse cardiovascular effects including endothelial dysfunction, inflammation, and oxidative stress.

Molecular Hydrogen: From Molecular Effects to Stem Cells Management and Tissue Regeneration

It is known that molecular hydrogen is a relatively stable, ubiquitous gas that is a minor component of the atmosphere. At the same time, in recent decades molecular hydrogen has been shown to have diverse biological effects. By the end of 2022, more than 2000 articles have been published in the field of hydrogen medicine, many of which are original studies. Despite the existence of several review articles on the biology of molecular hydrogen, many aspects of the research direction remain unsystematic. Therefore, the purpose of this review was to systematize ideas about the nature, characteristics, and mechanisms of the influence of molecular hydrogen on various types of cells, including stem cells. The historical aspects of the discovery of the biological activity of molecular hydrogen are presented. The ways of administering molecular hydrogen into the body are described. The molecular, cellular, tissue, and systemic effects of hydrogen are also reviewed. Specifically, the effect of hydrogen on various types of cells, including stem cells, is addressed. The existing literature indicates that the molecular and cellular effects of hydrogen qualify it to be a potentially effective agent in regenerative medicine.

Prevalence of hypertriglyceridemia among Royal Thai Army personnel and its related cardiometabolic risk factors, from 2017 to 2021

Background

Hypertriglyceridemia is a common health problem independently associated with an increased risk of atherosclerosis cardiovascular diseases (ASCVD), including ischemic heart disease and stroke. This study aims to determine the prevalence of hypertriglyceridemia among Royal Thai Army (RTA) personnel and its behavioral and cardiometabolic risk factors using the RTA personnel database of the physical health examination from 2017 to 2021.

Methods

A serial cross-sectional study was conducted from 2017 to 2021. A total of 257,683 active-duty RTA personnel aged 35–60 years were included in the study. We defined hypertriglyceridemia as fasting triglyceride ≥150 mg/dL. Moreover, we performed a multivariable logistic regression analysis to investigate behavioral and cardiometabolic risk factors for the prevalence of hypertriglyceridemia. The magnitude of the association was presented as an adjusted odds ratio (AOR) with a 95% confidence interval (CI).

Results

The hypertriglyceridemia prevalence among RTA personnel was 43.4% (95% CI: 42.9–43.8%) in 2017. It then continuously decreased to 40.3% (95% CI: 39.9–40.7%) in 2020 and slightly rose to 41.0% (95% CI: 40.6–41.4%) in 2021 (p for trend < 0.001). The prevalence of hypertriglyceridemia was higher for males than females (AOR 2.15; 95% CI: 2.07–2.23); RTA personnel aged 40–44 years compared with those aged 35–39 years (AOR 1.05; 95% CI: 1.02–1.08); and RTA personnel residing in the northeast (AOR; 1.15 95% CI: 1.11–1.18) and the north (AOR 1.05; 95% CI: 1.02–1.08) compared with those residing in Bangkok. The independent behavioral factors associated with hypertriglyceridemia included alcohol consumption, smoking, and sedentary behavior. Moreover, cardiometabolic risk factors, including higher body mass index, high fasting plasma glucose (≥ 100 mg/dL), high blood pressure (≥ 140/90 mmHg), and hypercholesterolemia (≥ 200 mg/dL), were significantly related to hypertriglyceridemia.

Conclusion

Our data demonstrated that hypertriglyceridemia is a frequent health issue, especially among males, participants aged 40–44 years, and RTA personnel residing in the northeast and the north. The prevalence of hypertriglyceridemia in this population was greatly influenced by alcohol consumption, cigarette smoking, and sedentary behavior. Both behavioral and cardiometabolic risk factors are potential targets for intervention to enhance the primary prevention of sequelae of hypertriglyceridemia, including ASCVD.

Role of Oxidative Stress in the Pathogenesis of Atherothrombotic Diseases

Oxidative stress is generated by the imbalance between reactive oxygen species (ROS) formation and antioxidant scavenger system’s activity. Increased ROS, such as superoxide anion, hydrogen peroxide, hydroxyl radical and peroxynitrite, likely contribute to the development and complications of atherosclerotic cardiovascular diseases (ASCVD). In genetically modified mouse models of atherosclerosis, the overexpression of ROS-generating enzymes and uncontrolled ROS formation appear to be associated with accelerated atherosclerosis. Conversely, the overexpression of ROS scavenger systems reduces or stabilizes atherosclerotic lesions, depending on the genetic background of the mouse model. In humans, higher levels of circulating biomarkers derived from the oxidation of lipids (8-epi-prostaglandin F_2α, and malondialdehyde), as well as proteins (oxidized low-density lipoprotein, nitrotyrosine, protein carbonyls, advanced glycation end-products), are increased in conditions of high cardiovascular risk or overt ASCVD, and some oxidation biomarkers have been reported as independent predictors of ASCVD in large observational cohorts. In animal models, antioxidant supplementation with melatonin, resveratrol, Vitamin E, stevioside, acacetin and n-polyunsaturated fatty acids reduced ROS and attenuated atherosclerotic lesions. However, in humans, evidence from large, placebo-controlled, randomized trials or prospective studies failed to show any athero-protective effect of antioxidant supplementation with different compounds in different CV settings. However, the chronic consumption of diets known to be rich in antioxidant compounds (e.g., Mediterranean and high-fish diet), has shown to reduce ASCVD over decades. Future studies are needed to fill the gap between the data and targets derived from studies in animals and their pathogenetic and therapeutic significance in human ASCVD.

Transcriptomic Evidence That Switching from Tobacco to Electronic Cigarettes Does Not Reverse Damage to the Respiratory Epithelium

The health benefits of switching from tobacco to electronic cigarettes (ECs) are neither confirmed nor well characterized. To address this problem, we used RNA-seq analysis to compare the nasal epithelium transcriptome from the following groups (n = 3 for each group): (1) former smokers who completely switched to second generation ECs for at least 6 months, (2) current tobacco cigarette smokers (CS), and (3) non-smokers (NS). Group three included one former cigarette smoker. The nasal epithelial biopsies from the EC users vs. NS had a higher number of differentially expressed genes (DEGs) than biopsies from the CS vs. NS and CS vs. EC sets (1817 DEGs total for the EC vs. NS, 407 DEGs for the CS vs. NS, and 116 DEGs for the CS vs. EC comparison). In the EC vs. NS comparison, enriched gene ontology terms for the downregulated DEGs included cilium assembly and organization, whereas gene ontologies for upregulated DEGs included immune response, keratinization, and NADPH oxidase. Similarly, ontologies for cilium movement were enriched in the downregulated DEGs for the CS vs. NS group. Reactome pathway analysis gave similar results and also identified keratinization and cornified envelope in the upregulated DEGs in the EC vs. NS comparison. In the CS vs. NS comparison, the enriched Reactome pathways for upregulated DEGs included biological oxidations and several metabolic processes. Regulator effects identified for the EC vs. NS comparison were inflammatory response, cell movement of phagocytes and degranulation of phagocytes. Disease Ontology Sematic Enrichment analysis identified lung disease, mouth disease, periodontal disease and pulmonary fibrosis in the EC vs. NS comparison. Squamous metaplasia associated markers, keratin 10, keratin 13 and involucrin, were increased in the EC vs. NS comparison. Our transcriptomic analysis showed that gene expression profiles associated with EC use are not equivalent to those from non-smokers. EC use may interfere with airway epithelium recovery by promoting increased oxidative stress, inhibition of ciliogenesis, and maintaining an inflammatory response. These transcriptomic alterations may contribute to the progression of diseases with chronic EC use.

Hydrogen agronomy: research progress and prospects

Agriculture is the foundation of social development. Under the pressure of population growth, natural disasters, environmental pollution, climate change, and food safety, the interdisciplinary "new agriculture" is becoming an important trend of modern agriculture. In fact, new agriculture is not only the foundation of great health and new energy sources, but is also the cornerstone of national food security, energy security, and biosafety. Hydrogen agronomy focuses mainly on the mechanism of hydrogen gas (H₂) biology effects in agriculture, and provides a theoretical foundation for the practice of hydrogen agriculture, a component of the new agriculture. Previous research on the biological effects of H₂ focused chiefly on medicine. The mechanism of selective antioxidant is the main theoretical basis of hydrogen medicine. Subsequent experiments have demonstrated that H₂ can regulate the growth and development of plant crops, edible fungus, and livestock, and enhance the tolerance of these agriculturally important organisms against abiotic and biotic stresses. Even more importantly, H₂ can regulate the growth and development of crops by changing the soil microbial community composition and structure. Use of H₂ can also improve the nutritional value and postharvest quality of agricultural products. Researchers have also shown that the biological functions of molecular hydrogen are mediated by modulating reactive oxygen species (ROS), nitric oxide (NO), and carbon monoxide (CO) signaling cascades in plants and microbes. This review summarizes and clarifies the history of hydrogen agronomy and describes recent progress in the field. We also argue that emerging hydrogen agriculture will be an important direction in the new agriculture. Further, we discuss several scientific problems in hydrogen agronomy, and suggest that the future of hydrogen agronomy depends on contributions by multiple disciplines. Important future research directions of hydrogen agronomy include hydrogen agriculture in special environments, such as islands, reefs, aircraft, and outer space.

Association of Left Ventricular Hypertrophy and Atrial Fibrillation with Hemorrhagic Evolution of Small Vessel Disease

OBJECTIVES

Cerebral small vessel disease (SVD) is often associated with hypertension and may evolve towards intracerebral hemorrhage (ICH) or lacunar ischemic stroke. However, the factors favoring the evolution towards ICH or lacunar stroke are not well understood.

MATERIALS AND METHODS

This retrospective study included 326 consecutive patients (71.1±13.2 years, 38% women): 143 with deep ICH and 183 with lacunar lesions (LL) <2 cm, which were visible in a deep location on brain CT scan. Among LL patients, 143 had a small-artery occlusion (SAO) stroke according to the TOAST classification. Clinical characteristics plus laboratory and neuroradiological variables of these patients had been prospectively collected and a subgroup underwent echocardiography.

RESULTS

In multivariate analysis, ICH patients (97% hypertensive), compared to SAO patients (89% hypertensive), had greater left ventricular wall thickness (LVWT; OR 4.15, 95%CI 1.64-10.53, for those with LVWT ≥ 1.4 cm, 70% of whom were hemorrhagic) and lower prevalence of white matter lesions (OR 0.30, 95%CI 0.13-0.70), ever smokers (OR 0.39, 95%CI 0.18-0.82) and diabetics (OR 0.29, 95% CI 0.10-0.84). Moreover, ICH patients had a greater prevalence of atrial fibrillation than LL patients (OR 3.14, 95%CI 1.11-8.93), and so they were more often anticoagulated.

CONCLUSIONS

Most SVD patients were hypertensive, but those evolving towards ICH were characterized by organ damage at the cardiac level (increase in LVWT and atrial fibrillation), while those evolving towards lacunar stroke were characterized by a higher prevalence of smokers and diabetics, and by organ damage at the cerebral level (white matter lesions).

Habitual cigarette smoking attenuates shear-mediated dilation in the brachial artery but not in the carotid artery in young adults

In the present study, we hypothesized that habitual cigarette smoking attenuates endothelial function in the cerebral circulation as well as that of the peripheral circulation in young adults. To test this hypothesis, we measured cerebrovascular and peripheral flow‐mediated dilation (FMD) in young smokers and nonsmokers in the present study. Ten healthy nonsmokers and 10 smokers participated in the study. We measured blood velocity and diameter in the brachial artery and internal carotid artery (ICA) using Doppler ultrasound. We identified shear‐mediated dilation in the brachial artery and ICA by the percentage change in peak diameter during hyperemia stimulation (reactive hyperemia and hypercapnia). We measured the baseline diameter and the shear rate area under the curve from the onset of hyperemia to peak dilation in the brachial artery and ICA, finding the measurements of the smokers and those of the nonsmokers did not differ (p > .05). In contrast to brachial FMD (5.07 ± 1.79% vs. 7.92 ± 3.01%; smokers vs. nonsmokers, p = .019), FMD in the ICA was not attenuated in the smokers compared with that of the nonsmokers (5.46 ± 2.32% vs. 4.57 ± 2.70%; p = .442). These findings indicate that in young healthy smokers, cerebral endothelial function was preserved, and the response of cerebral endothelial function to smoking was different from that of peripheral vasculature.

Cardiovascular injury induced by tobacco products: assessment of risk factors and biomarkers of harm. A Tobacco Centers of Regulatory Science compilation

Although substantial evidence shows that smoking is positively and robustly associated with cardiovascular disease (CVD), the CVD risk associated with the use of new and emerging tobacco products, such as electronic cigarettes, hookah, and heat-not-burn products, remains unclear. This uncertainty stems from lack of knowledge on how the use of these products affects cardiovascular health. Cardiovascular injury associated with the use of new tobacco products could be evaluated by measuring changes in biomarkers of cardiovascular harm that are sensitive to the use of combustible cigarettes. Such cardiovascular injury could be indexed at several levels. Preclinical changes contributing to the pathogenesis of disease could be monitored by measuring changes in systemic inflammation and oxidative stress, organ-specific dysfunctions could be gauged by measuring endothelial function (flow-mediated dilation), platelet aggregation, and arterial stiffness, and organ-specific injury could be evaluated by measuring endothelial microparticles and platelet-leukocyte aggregates. Classical risk factors, such as blood pressure, circulating lipoproteins, and insulin resistance, provide robust estimates of risk, and subclinical disease progression could be followed by measuring coronary artery Ca2+ and carotid intima-media thickness. Given that several of these biomarkers are well-established predictors of major cardiovascular events, the association of these biomarkers with the use of new and emerging tobacco products could be indicative of both individual and population-level CVD risk associated with the use of these products. Differential effects of tobacco products (conventional vs. new and emerging products) on different indexes of cardiovascular injury could also provide insights into mechanisms by which they induce cardiovascular harm.

Effect of Coronary Slow Flow on Intrinsicoid Deflection of QRS Complex

Coronary slow flow is a rare, clinically important entity observed in acute coronary syndrome. The pathophysiological mechanism is not fully elucidated. We investigated patients with chest pain who had angiographic features consistent with the coronary slow flow. One hundred ten patients were included. Electrocardiography, echocardiography, and angiography results were retrospectively noted. The mean age was 56.4. Fifty-eight were male, and fifty-two were female. The control group consisted of patients with normal angiography. Patients had higher diastolic blood pressure, lower mean ejection fraction, higher average left ventricular end-diastolic diameter, and higher mean left atrial size than the control group (p=0.009, p=0.017, p=0.041, andp < 0.001, resp.). Patients had higher average V1 ID, V6 ID, P wave dispersion, TFC LAD, TFC Cx, TFC RCA, and TFC levels than the control group. A significant linear positive relationship was found between the V1 ID and the TFC LAD, TFC Cx, TFC RCA, and TFC; also between the V6 ID and the TFC LAD, TFC Cx, TFC RCA, and TFC. Angiographic and electrocardiographic features are suggestive and diagnostic for the coronary slow flow syndrome. Although when regarded as a benign condition, coronary slow flow should be diagnosed, followed up, and treated as many of laboratory features suggest ischemic events.

Biomarkers for differentiation of causes of respiratory distress in dogs and cats: Part 2--Lower airway, thromboembolic, and inflammatory diseases

OBJECTIVES

To review the current veterinary and relevant human literature regarding biomarkers of respiratory diseases leading to dyspnea and to summarize the availability, feasibility, and practicality of using respiratory biomarkers in the veterinary setting.

DATA SOURCES

Veterinary and human medical literature: original research articles, scientific reviews, consensus statements, and recent textbooks.

HUMAN DATA SYNTHESIS

Numerous biomarkers have been evaluated in people for discriminating respiratory disease processes with varying degrees of success.

VETERINARY DATA SYNTHESIS

Although biomarkers should not dictate clinical decisions in lieu of gold standard diagnostics, their use may be useful in directing care in the stabilization process. Serum immunoglobulins have shown promise as an indicator of asthma in cats. A group of biomarkers has also been evaluated in exhaled breath. Of these, hydrogen peroxide has shown the most potential as a marker of inflammation in asthma and potentially aspiration pneumonia, but methods for measurement are not standardized. D-dimers may be useful in screening for thromboembolic disease in dogs. There are a variety of markers of inflammation and oxidative stress, which are being evaluated for their ability to assess the severity and type of underlying disease process. Of these, amino terminal pro-C-type natriuretic peptide may be the most useful in determining if antibiotic therapy is warranted. Although critically evaluated for their use in respiratory disorders, many of the biomarkers which have been evaluated have been found to be affected by more than one type of respiratory or systemic disease.

CONCLUSION

At this time, there are point-of-care biomarkers that have been shown to reliably differentiate between causes of dyspnea in dogs and cats. Future clinical research is warranted to understand of how various diseases affect the biomarkers and more bedside tests for their utilization.

Application of CE-MS to a metabonomics study of human urine from cigarette smokers and non-smokers

BACKGROUND

Novel biomarkers of exposure and early adverse effects are needed for comparative studies of combustible and non-combustible tobacco products for regulatory authority evaluation. Metabolic biomarkers reflect both gene and environmental effects.

RESULTS

CE-MS has been applied to human urine samples from non-smokers and smokers of cigarettes at two tar levels. Validated chemometric models were able to separate smokers from non-smokers, with discrimination mainly based on the presence of nicotine metabolites. With these removed, it still proved possible to discriminate smokers from non-smokers with models now based on endogenous metabolites. The biochemical relevance of these biomarkers is discussed.

CONCLUSION

This proof-of-principle metabonomics study illustrates the potential of CE-MS to discover novel biomarkers in urine from tobacco users.

Molecular hydrogen as a novel antioxidant: overview of the advantages of hydrogen for medical applications

Molecular hydrogen (H2) was believed to be inert and nonfunctional in mammalian cells. We overturned this concept by demonstrating that H2 reacts with highly reactive oxidants such as hydroxyl radical ((•)OH) and peroxynitrite (ONOO(-)) inside cells. H2 has several advantages exhibiting marked effects for medical applications: it is mild enough neither to disturb metabolic redox reactions nor to affect signaling by reactive oxygen species. Therefore, it should have no or little adverse effects. H2 can be monitored with an H2-specific electrode or by gas chromatography. H2 rapidly diffuses into tissues and cells to exhibit efficient effects. Thus, we proposed the potential of H2 for preventive and therapeutic applications. There are several methods to ingest or consume H2: inhaling H2 gas, drinking H2-dissolved water (H2-water), injecting H2-dissolved saline (H2-saline), taking an H2 bath, or dropping H2-saline onto the eyes. Recent publications revealed that, in addition to the direct neutralization of highly reactive oxidants, H2 indirectly reduces oxidative stress by regulating the expression of various genes. Moreover, by regulating gene expression, H2 functions as an anti-inflammatory, antiallergic, and antiapoptotic molecule, and stimulates energy metabolism. In addition to growing evidence obtained by model animal experiments, extensive clinical examinations were performed or are under way. Since most drugs specifically act on their specific targets, H2 seems to differ from conventional pharmaceutical drugs. Owing to its great efficacy and lack of adverse effects, H2 has potential for clinical applications for many diseases.

Role of unfolded protein response dysregulation in oxidative injury of retinal pigment epithelial cells

AIMS

Age-related macular degeneration (AMD), a major cause of legal blindness in the elderly, is associated with genetic and environmental risk factors, such as cigarette smoking. Recent evidence shows that cigarette smoke (CS) that contains high levels of potent oxidants preferably targets retinal pigment epithelium (RPE) leading to oxidative damage and apoptosis; however, the mechanisms are poorly understood. The present study aimed to investigate the role of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) in CS-related RPE apoptosis.

RESULTS

ER stress and proapoptotic gene C/EBP homologous protein (CHOP) were induced in the RPE/choroid complex from mice exposed to CS for 2 weeks and in human RPE cells treated with hydroquinone, a potent oxidant found at high concentrations in CS. Suppressing ER stress or inhibiting CHOP activation by pharmacological chaperones or genetic approaches attenuated hydroquinone-induced RPE cell apoptosis. In contrast to enhanced CHOP activation, protein level of active X-box binding protein 1 (XBP1), a major regulator of the adaptive UPR, was reduced in hydroquinone-treated cells. Conditional knockout of XBP1 gene in the RPE resulted in caspase-12 activation, increased CHOP expression, and decreased antiapoptotic gene Bcl-2. Furthermore, XBP1-deficient RPE cells are more sensitive to oxidative damage induced by hydroquinone or NaIO3, a CS-unrelated chemical oxidant. Conversely, overexpressing XBP1 protected RPE cells and attenuated oxidative stress-induced RPE apoptosis.

INNOVATION AND CONCLUSION

These findings provide strong evidence suggesting an important role of ER stress and the UPR in CS-related oxidative injury of RPE cells. Thus, the modulation of the UPR signaling may provide a promising target for the treatment of AMD.

Molecular hydrogen as a preventive and therapeutic medical gas: initiation, development and potential of hydrogen medicine

Molecular hydrogen (H2) has been accepted to be an inert and nonfunctional molecule in our body. We have turned this concept by demonstrating that H2 reacts with strong oxidants such as hydroxyl radical in cells, and proposed its potential for preventive and therapeutic applications. H2 has a number of advantages exhibiting extensive effects: H2 rapidly diffuses into tissues and cells, and it is mild enough neither to disturb metabolic redox reactions nor to affect signaling reactive oxygen species; therefore, there should be no or little adverse effects of H2. There are several methods to ingest or consume H2; inhaling H2 gas, drinking H2-dissolved water (H2-water), injecting H2-dissolved saline (H2-saline), taking an H2 bath, or dropping H2-saline into the eyes. The numerous publications on its biological and medical benefits revealed that H2 reduces oxidative stress not only by direct reactions with strong oxidants, but also indirectly by regulating various gene expressions. Moreover, by regulating the gene expressions, H2 functions as an anti-inflammatory and anti-apoptotic, and stimulates energy metabolism. In addition to growing evidence obtained by model animal experiments, extensive clinical examinations were performed or are under investigation. Since most drugs specifically act to their targets, H2 seems to differ from conventional pharmaceutical drugs. Owing to its great efficacy and lack of adverse effects, H2 has promising potential for clinical use against many diseases.

Lung cancer biomarkers for the assessment of modified risk tobacco products: an oxidative stress perspective

Manufacturers have developed prototype cigarettes yielding reduced levels of some tobacco smoke toxicants, when tested using laboratory machine smoking under standardised conditions. For the scientific assessment of modified risk tobacco products, tests that offer objective, reproducible data, which can be obtained in a much shorter time than the requirements of conventional epidemiology are needed. In this review, we consider whether biomarkers of biological effect related to oxidative stress can be used in this role. Based on published data, urinary 8-oxo-7,8-dihydro-2-deoxyguanosine, thymidine glycol, F2-isoprostanes, serum dehydroascorbic acid to ascorbic acid ratio and carotenoid concentrations show promise, while 4-hydroxynonenal requires further qualification.

Recent progress toward hydrogen medicine: potential of molecular hydrogen for preventive and therapeutic applications

Persistent oxidative stress is one of the major causes of most lifestyle-related diseases, cancer and the aging process. Acute oxidative stress directly causes serious damage to tissues. Despite the clinical importance of oxidative damage, antioxidants have been of limited therapeutic success. We have proposed that molecular hydrogen (H₂) has potential as a “novel” antioxidant in preventive and therapeutic applications [Ohsawa et al., Nat Med. 2007: 13; 688-94]. H₂ has a number of advantages as a potential antioxidant: H₂ rapidly diffuses into tissues and cells, and it is mild enough neither to disturb metabolic redox reactions nor to affect reactive oxygen species (ROS) that function in cell signaling, thereby, there should be little adverse effects of consuming H₂. There are several methods to ingest or consume H₂, including inhaling hydrogen gas, drinking H₂-dissolved water (hydrogen water), taking a hydrogen bath, injecting H₂-dissolved saline (hydrogen saline), dropping hydrogen saline onto the eye, and increasing the production of intestinal H₂ by bacteria. Since the publication of the first H₂ paper in Nature Medicine in 2007, the biological effects of H₂ have been confirmed by the publication of more than 38 diseases, physiological states and clinical tests in leading biological/medical journals, and several groups have started clinical examinations. Moreover, H₂ shows not only effects against oxidative stress, but also various anti-inflammatory and anti-allergic effects. H₂ regulates various gene expressions and protein-phosphorylations, though the molecular mechanisms underlying the marked effects of very small amounts of H₂ remain elusive.

Serum oxidative stress-induced repression of Nrf2 and GSH depletion: a mechanism potentially involved in endothelial dysfunction of young smokers

Background

Although oxidative stress plays a major role in endothelial dysfunction (ED), the role of glutathione (GSH), of nuclear erythroid-related factor 2 (Nrf2) and of related antioxidant genes (ARE) are yet unknown. In this study we combined an in vivo with an in vitro model to assess whether cigarette smoking affects flow-mediated vasodilation (FMD), GSH concentrations and the Nrf2/ARE pathway in human umbilical vein endothelial cells (HUVECs).

Methods and Results

52 healthy subjects (26 non-smokers and 26 heavy smokers) were enrolled in this study. In smokers we demonstrated increased oxidative stress, i.e., reduced concentrations of GSH and increased concentrations of oxidation products of the phospholipid 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine (oxPAPC) in serum and in peripheral blood mononuclear cells (PBMC), used as in vivo surrogates of endothelial cells. Moreover we showed impairment of FMD in smokers and a positive correlation with the concentration of GSH in PBMC of all subjects. In HUVECs exposed to smokers' serum but not to non-smokers' serum we found that oxidative stress increased, whereas nitric oxide and GSH concentrations decreased; interestingly the expression of Nrf2, of heme oxygenase-1 (HO-1) and of glutamate-cysteine ligase catalytic (GCLC) subunit, the rate-limiting step of synthesis of GSH, was decreased. To test the hypothesis that the increased oxidative stress in smokers may have a causal role in the repression of Nrf2/ARE pathway, we exposed HUVECs to increasing concentrations of oxPAPC and found that at the highest concentration (similar to that found in smokers' serum) the expression of Nrf2/ARE pathway was reduced. The knockdown of Nrf2 was associated to a significant reduction of HO-1 and GCLC expression induced by oxPAPC in ECs.

Conclusions

In young smokers with ED a novel further consequence of increased oxidative stress is a repression of Nrf2/ARE pathway leading to GSH depletion.

Effect of follicular fluid oxidative stress parameters on intracytoplasmic sperm injection outcome

OBJECTIVE

The purpose of this study was to evaluate the association between the follicular fluid (FF) reactive oxygen species (ROS) levels, total antioxidant capacity (TAC) and ROS-TAC score and pregnancy after intracytoplasmic sperm injection (ICSI).

METHODS

A total of 138 consecutive women who had ICSI were included in this study. FF ROS and TAC were measured by enhanced chemiluminescence and colorimetric assay, respectively, and then the ROS-TAC score was calculated.

RESULTS

Out of the 138 included patients, 42 (30%) achieved pregnancy after ICSI. Log ROS, TAC, and the ROS-TAC score were not significantly different across diagnoses. Pregnant cycles were associated with significantly lower ROS (P < 0.001), higher TAC (P < 0.001) and higher ROS-TAC scores (P < 0.001). After adjusting for age, there was a significant positive correlation between log ROS and the number of follicles on the day of HCG administration (correlation 0.20, 95% CI: 0.02, 0.39) as well as the number of oocytes retrieved (correlation 0.18, 0.001, 0.36) but not with TAC. Interestingly, in women with endometriosis, higher TAC levels and higher ROS-TAC scores were associated with a higher likelihood of finding normal oocytes (P = 0.005 and P = 0.002, respectively).

CONCLUSION

Higher FF TAC, higher FF ROS-TAC scores and lower FF ROS levels are associated with pregnancy after ICSI. Oxidative stress parameters may be markers of metabolic activity within the follicle.

Endothelial function and left ventricular remodeling in diabetic and non-diabetic patients after acute coronary syndrome

BACKGROUND

Endothelial dysfunction is an independent predictor of future cardiac events.

MATERIAL/METHODS

We evaluated the relationship between flow-mediated dilation (FMD) in brachial artery and coronary risk factors in 93 patients (70 males, mean age: 62 ± 8 years) with ACS treated with primary angioplasty (PCI). The patients were divided into 2 subgroups: 43 patients with diabetes mellitus type 2 (DM) and 50 non-diabetics (non-DM). Patients were examined on the 3rd day after ACS and after 6 months. FMD on the 3rd day were significantly lower in DM than in non-DM (5.8 ± 2.2% vs. 8.8 ± 4.9%, p=0.0007) and after 6 months (6.2 ± 2.6% vs. 9.4 ± 4.4%, p<0.0001). It was also observed that the improvement of FMD in both groups after a 6-month follow-up inversely correlated with the increase of left ventricular end-diastolic volume (LVEDV) (r=-0.41, p<0.001).

RESULTS

There was an inverse relationship between FMD and age (r=-0.26, p<0.01), BMI (r=-0.26, p<0,005), total cholesterol (r=-0.56, p<0.001) and LDL cholesterol (r=-0.53, p<0.001). There was no relationship between triglycerides, hypertension and history of smoking. In the DM group, FMD negatively correlated with HbA1c (r=-0.68, p<0.001). Restenosis rate was significantly higher in the DM group (19% vs. 6%, p<0.001) but there was no relationship between FMD and restenosis.

CONCLUSIONS

Impaired FMD is more significant in diabetics than in non-diabetic patients with ACS. Lack of improvement of FMD after acute coronary syndrome can be a predictor of detrimental left ventricular remodeling in patients with ACS.

Endothelial function in individuals with coronary artery disease with and without type 2 diabetes mellitus

The goal of this study was to determine if individuals with coronary artery disease (CAD) and type 2 diabetes mellitus (T2DM) had greater endothelial dysfunction (ED) than individuals with only CAD. Flow-mediated dilation (FMD), calculated as percentage increase in brachial artery diameter in response to postischemic blood flow, was measured after an overnight fast in 2 cohorts. The first cohort included 76 participants in the Northern Manhattan Study with CAD; 25 also had T2DM. The second cohort was composed of 27 individuals with both T2DM and CAD who were participants in a study of postprandial lipemia. Combined, we analyzed 103 patients with CAD: 52 with T2DM (T2DM+) and 51 without T2DM (T2DM-). The 52 CAD T2DM+ subjects had a mean FMD of 3.9% +/- 3.2%, whereas the 51 CAD T2DM- subjects had a greater mean FMD of 5.5% +/- 4.0% (P < .03). An investigation of various confounders known to affect FMD identified age and body mass index as the only significant covariates in a multiple regression model. Adjusting for age and body mass index, we found that FMD remained lower in T2DM+ subjects compared with T2DM- subjects (difference, -1.99%; P < .03). In patients with CAD, the concomitant presence of T2DM is independently associated with greater ED, as measured by FMD. This finding may be relevant to the greater early and late morbidity and mortality observed in patients with both CAD and T2DM.

Obstructive sleep apnea causes oxidative damage to plasma lipids and proteins and decreases adiponectin levels

PUPOSE: Obstructive sleep apnea (OSA) is associated with various metabolic disorders, and oxidative stress was suggested to play an important role. In the present study, we aimed to investigate serum adiponectin and oxidative stress markers, especially protein carbonyls, and to evaluate the correlation between these parameters and lipid, insulin and fasting glucose concentrations in OSA patients and controls.

METHOD

Blood was drawn from healthy male volunteers following full-night polysomnographic evaluation. Subjects were classified as controls (n = 24), mild OSA group (n = 9) and moderate-severe OSA group (n = 17) according to their apnea-hypopnea indices (AHIs). Serum lipids, fasting glucose, adiponectin, malondialdehyde (MDA), protein carbonyl concentrations, and paraoxonase activities were measured in all subjects.

RESULTS

Results of this study indicated that serum adiponectin concentrations were significantly decreased and MDA and protein carbonyl concentrations were significantly elevated in OSA patients compared to the controls. Protein carbonyl and MDA concentrations were significantly and positively correlated with AHI, while a significant negative correlation was found between adiponectin concentrations and AHI. Adiponectin levels were negatively correlated with MDA levels.

CONCLUSION

Results of this study, which is the first human study investigating and describing serum protein carbonyl concentrations in OSA patients, reveal that OSA causes increments in oxidative damage and decreases adiponectin levels. The recurrent hypoxia-reoxygenation attacks in OSA patients may activate oxidative stress, elevating sympathetic activity and leading to low levels of adiponectin.

Impaired endothelial function assessed by flow-mediated vasodilatation in workers occupationally exposed to lead

The aim of the study was to examine endothelial function in workers occupationally exposed to lead by means of FMD (flow-mediated dilatation). 44 men professionally exposed to lead, smelters and refiners, employees working at copper smelter and control group of 41 healthy men were enrolled into the study. Within the group of men occupationally exposed to lead the absolute increase in diameter after ischaemia (BAD, brachial artery diameter) and flow-mediated dilation were statistically less significant when compared to those of the control group. There was a negative linear correlation between FMD and lead concentration in copper smelters (r=-0.64). Multivariate backward step-wise regression analysis showed that blood lead concentration in copper smelters independently influenced the impairment of endothelial function expressed as decreased FMD value. In conclusion, results of our study suggest that endothelial function assessed by flow-mediated dilatation was impaired in workers occupationally exposed to lead.

Chronic smoking prevents amelioration of endothelial function in the course of the menstrual cycle

BACKGROUND

Smoking is the most important modifiable cardiovascular risk factor in young women. The aim of this study was to investigate whether tobacco use influences physiological changes in endothelial function during the menstrual cycle.

METHODS AND RESULTS

Flow-mediated dilation (FMD) and nitro-mediated dilation (NMD) were assessed in healthy smoking and non-smoking women, by high-resolution ultrasound at 3 time points during the menstrual cycle: at menstruation, in the mid-follicular phase, and in the mid-luteal phase. A total of 25 women (12 non-smokers, 13 smokers) completed the study protocol. FMD did not show differences between smoking and non-smoking women at menstruation and the mid-follicular phase. At the mid-luteal phase, however, FMD was significantly reduced in smoking when compared with non-smoking women. NMD did not differ between smoking and non-smoking women, nor between the different cycle phases.

CONCLUSIONS

In healthy women, smoking eliminates the physiological amelioration of endothelial function during the menstrual cycle. This study underlines the importance of an exact description of menstrual cycle phase and smoking status in studies investigating endothelial function in premenopausal women.

Endothelial dysfunction, carotid artery plaque burden, and conventional exercise-induced myocardial ischemia as predictors of coronary artery disease prognosis

Background

While both flow-mediated vasodilation (FMD) in the brachial artery (BA), which measures endothelium-dependent vasodilatation, and intima-media thickness (IMT) in the carotid artery are correlated with the prognosis of coronary artery disease (CAD), it is not clear which modality is a better predictor of CAD. Furthermore, it has not been fully determined whether either of these modalities is superior to conventional ST-segment depression on exercise stress electrocardiogram (ECG) as a predictor. Thus, the goal of the present study was to compare the predictive value of FMD, IMT, and stress ECG for CAD prognosis.

Methods and Results

A total of 103 consecutive patients (62 ± 9 years old, 79 men) with clinically suspected CAD had FMD and nitroglycerin-induced dilation (NTG-D) in the BA, carotid artery IMT measurement using high-resolution ultrasound, and exercise treadmill testing. The 73 CAD patients and 30 normal coronary patients were followed for 50 ± 15 months. Fifteen patients had coronary events during this period (1 cardiac death, 2 non-fatal myocardial infarctions, 3 acute heart failures, and 9 unstable anginas). On Kaplan-Meier analysis, only FMD and stress ECG were significant predictors for cardiac events.

Conclusion

Brachial endothelial function as reflected by FMD and conventional exercise stress testing has comparable prognostic value, whereas carotid artery plaque burden appears to be less powerful for predicting future cardiac events.

The relation between coronary flow rate, plasma endothelin-1 concentrations, and clinical characteristics in patients with normal coronary arteries

BACKGROUND

Coronary slow flow (CSF) is characterized by delayed opacification of epicardial arteries in the absence of occlusive disease. In the present study, we aimed to investigate the relation between coronary flow rate, plasma endothelin-1 (ET-1) concentrations, and clinical characteristics in patients with normal coronary arteries.

METHODS

The study population included 77 patients with angiographically normal coronary arteries who underwent coronary angiography on suspicion of ischemic heart disease due to typical chest pain or ischemic findings on treadmill exercise test or myocardial scintigraphy. Based on the Thrombolysis In Myocardial Infarction frame count (TFC), patients were grouped into those with normal coronary flow and those with slow coronary flow.

RESULTS

Forty-eight (61.5%) patients were found to have CSF. Plasma ET-1 concentrations were significantly higher with the presence of CSF (P=.03). There were significant differences between plasma ET-1 concentrations, and mean TFC, TFC for left anterior descending coronary artery (LAD), TFC for left circumflex coronary artery (CX), and TFC for right coronary artery separately in patients with and without CSF (P=.033, P<.001, P<.001, P<.001, and P<.001, respectively). Mean TFC, TFC for LAD, and TFC for CX, and ET-1 concentrations were significantly higher in smokers than in nonsmokers (P<.001, P<.001, P=.004, and P=.033, respectively). However, logistic regression analysis suggested that ET-1 concentration was not an independent determinant of CSF.

CONCLUSIONS

Although there is a significant relation between ET-1 concentrations and coronary flow rate, ET-1 concentrations are not sufficient to determine the presence of CSF. Smoking is strongly associated with CSF, TFC, and increased ET-1 concentrations.

Smoking, inflammatory patterns and postprandial hypertriglyceridemia

BACKGROUND

Smoking is associated with increased postprandial hypertriglyceridemia (PPT). Inflammation and insulin resistance are potential "drivers" for this phenomenon. We tested whether inflammatory patterns and/or insulin resistance explain the effect of smoking on PPT.

METHODS AND RESULTS

Men and women in the NHLBI Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN) study (n=1036, age 49+/-16y) were included. Each participant was asked to suspend use of lipid-lowering drugs for 3 weeks and was given a high-fat milkshake (83% fat and 700kcal/m(2)). Triglyceride concentrations at 0, 3.5 and 6h after the fat load were measured. Inflammatory markers were measured at baseline. Principal component analysis was used to derive inflammatory patterns from individual inflammatory markers (hsCRP, IL2 soluble receptor-alpha, IL6, TNF-alpha and MCP1). Insulin resistance (IR) was estimated using the HOMA equation. Repeated measures-ANOVA was used for analyses. Two inflammatory patterns, namely CRP-IL6 pattern and MCP1-TNF-alpha pattern, were derived. We found significant main (smoking and time) and interaction (smokingxtime) effects (P<0.01) for triglycerides. The multivariate-adjusted triglyceride (mg/dL) concentrations (mean+/-S.E.M.) for never, past and current smokers were 127.38+/-1.04, 119.82+/-1.05 and 134.92+/-1.08 at 0h; 229.42+/-1.04, 238.39+/-1.05 and 293.94+/-1.08 at 3.5h; and 194.63+/-1.04, 208.38+/-1.05 and 248.27+/-1.08 at 6h after the fat load, respectively. Smoking remained significant after adjusting for HOMA-IR and/or inflammatory patterns which showed independent associations with PPT (P<0.05).

CONCLUSIONS

These data confirm impaired metabolism of fat among smokers and suggest that mechanisms other than inflammation or insulin resistance may explain the observed hypertriglyceridemia among smokers.

High intravascular pressure attenuates vascular dilation responses of small mesenteric arteries in the rat

BACKGROUND

Alterations in intravascular pressure can affect vascular function and the morphological properties of arteries. Although it has been shown that a transient elevation of blood pressure impairs endothelium-dependent dilation in small arteries, the vascular dilation responses during high intravascular pressure have not yet been investigated.

METHODS AND RESULTS

Using pressure myography, the endothelium-dependent and -independent dilation responses of small mesenteric arteries of rats were examined under 3 different intravascular pressure conditions (50, 80 and 120 mmHg). Endothelium-dependent dilation was evaluated by measuring vasodilator responses to increasing doses of acetylcholine (ACh, 10(-9) to 10(-4) mol/L) or increases in intraluminal flow (7-36 microl/min). Endothelium-independent vasodilator function was examined by using sodium nitroprusside (SNP, 10(-9) to 10(-4) mol/L). Flow-mediated dilation was significantly attenuated at 120 mmHg whereas ACh-induced dilation was progressively decreased with increases in intravascular pressure (at 80 and 120 mmHg). Significant attenuation in the vasodilator response to SNP was also observed at 80 and 120 mmHg.

CONCLUSION

Endothelium-dependent and-independent dilation responses are progressively attenuated with acute increases in intravascular pressure.

Baseline ICAM-1 and VCAM-1 are increased in initially healthy middle-aged men who develop cardiovascular disease during 6.6 years of follow-up

The objective of the present study was to investigate if there was a difference in baseline serum concentrations of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) between groups with and without cardiovascular events during a mean follow-up of 6.6 years in a group of initially healthy 58-year-old men. A further aim was to examine if high serum concentrations of ICAM-1 and VCAM-1 were associated with carotid and femoral artery plaque occurrence, separately. Men with cardiovascular events during follow-up had higher median serum ICAM-I and VCAM-I than those without events (P < .05). The median of serum ICAM-I and VCAM-1 in the event group was used as the cutoff level, and in those with ICAM-1 and VCAM-1 above the cutoff value, there was an increased risk of having a plaque in the femoral artery (OR = 2.8, 95% CI = 1.8-4.3; and OR = 1.6, 95% CI = 1.1-2.5, respectively).

Association of serum uric acid level and coronary blood flow

OBJECTIVES

Slow coronary flow (SCF) has long since been identified and endothelial dysfunction and atherosclerosis of the epicardial coronary arteries and microvasculature are reported to be associated with SCF. Serum uric acid is an independent biochemical marker of atherosclerosis, oxidative stress and endothelial dysfunction. Consequently, we aimed to investigate the association between coronary blood flow and serum uric acid level by means of thrombolysis in myocardial infarction frame count (TFC) and other laboratory parameters, in patients with SCF compared with control participants.

METHODS

Sixty-four patients with SCF and 369 control participants with normal coronary flow were studied after quantifying coronary blood flow according to TFC. Serum uric acid levels were determined using commercially available assay kits. The association between TFC and serum uric acid level and other clinical and laboratory parameters were evaluated.

RESULTS

Statistically significant differences were present between SCF and control groups with respect to serum uric acid, and hemoglobin levels, heart rate, cigarette smoking and sex (P<0.05 for all). The mean TFC was significantly correlated with serum uric acid, urea, creatinine, high-density lipoprotein-cholesterol and hemoglobin levels, platelet count, male gender, cigarette smoking, heart rate and systolic blood pressure (P<0.05 for all). Serum uric acid level (chi(2)=22.86, beta=0.54, P<0.001), heart rate (chi(2)=7.42, beta=-0.034, P=0.032) and cigarette smoking (chi(2)=12.343, beta=0.969, P=0.025) were independent predictors of SCF, whereas serum uric acid level was the only independent predictor of the mean TFC (beta=0.298, P<0.001).

CONCLUSIONS

These findings have shown that serum uric acid level is significantly associated with coronary blood flow and that elevated uric acid might be an independent predictor for the presence of SCF.