Smoking impairs the activity of endothelial nitric oxide synthase in saphenous vein

Interstitial lung disease in patients with antineutrophil cytoplasmic antibody-associated vasculitis: chest CT patterns and correlation with survival

BACKGROUND

Interstitial lung disease (ILD) is common in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), with usual interstitial pneumonia (UIP) being the most frequent pattern. The impact of different ILD patterns on clinical outcomes remains unclear.

METHODS

Retrospective cohort study included patients with AAV (MPA and GPA) and ILD confirmed by chest CT scans between 1997 and 2021. ILD patterns were classified according to 2018 Fleischner Society criteria.

RESULTS

Of 1862 patients in the Mayo AAV Cohort, 143 (7.7 %) had ILD on chest CT. The median age at the time of ILD diagnosis (occurring before AAV diagnosis in 26.6 %) was 69 years (IQR 61-75); 60 % were male, and 75 % were MPO-positive. On chest CT, "typical UIP" pattern was identified in 44 patients (30.8 %), whereas 13 (9.1 %) manifested "probable UIP" pattern, 37 (25.9 %) "indeterminate for UIP" pattern, and 49 (34.3 %) "non-UIP" pattern. Among MPO-ANCA patients, typical UIP pattern was most common (37.4 %), while non-UIP pattern was most common (58.3 %) among PR3-ANCA patients. Patients with typical UIP pattern, when compared to those with non-UIP pattern, were more commonly male (70.5 %), MPO-ANCA (90.0 %), diagnosed before the onset of AAV (40.9 %), and had reduced diffusion capacity on pulmonary function tests. The presence of typical UIP was related with higher survival at 12 months and 10 years in MPO-ANCA patients when compared to other ILD patterns (IRR 8.201 and IRR 2.179).

CONCLUSIONS

The typical UIP pattern in AAV-ILD is associated with better survival, particularly in MPO-ANCA patients, suggesting distinct mechanisms for ILD development in MPO vs. PR3-AAV.

The Pathological Mechanisms and Therapeutic Molecular Targets in Arteriovenous Fistula Dysfunction

The number of patients with end-stage renal disease (ESRD) requiring hemodialysis is increasing worldwide. Although arteriovenous fistula (AVF) is the best and most important vascular access (VA) for hemodialysis, its primary maturation failure rate is as high as 60%, which seriously endangers the prognosis of hemodialysis patients. After AVF establishment, the venous outflow tract undergoes hemodynamic changes, which are translated into intracellular signaling pathway cascades, resulting in an outward and inward remodeling of the vessel wall. Outward remodeling refers to the thickening of the vessel wall and the dilation of the lumen to accommodate the high blood flow in the AVF, while inward remodeling is mainly characterized by intimal hyperplasia. More and more studies have shown that the two types of remodeling are closely related in the occurrence and development of, and jointly determining the final fate of, AVF. Therefore, it is essential to investigate the underlying mechanisms involved in outward and inward remodeling for identifying the key targets in alleviating AVF dysfunction. In this review, we summarize the current clinical diagnosis, monitoring, and treatment techniques for AVF dysfunction and discuss the possible pathological mechanisms related to improper outward and inward remodeling in AVF dysfunction, as well as summarize the similarities and differences between the two remodeling types in molecular mechanisms. Finally, the representative therapeutic targets of potential clinical values are summarized.

Development of a novel predictive model for interstitial lung disease in ANCA-associated vasculitis prognostications within the Chinese population

Antineutrophil cytoplasmic antibody vasculitis-associated interstitial lung disease (AAV-ILD) is a potentially life-threatening disease. However, very little research has been done on the condition's mortality risk. Hence, our objective is to find out the factors influencing the prognosis of AAV-ILD and employ these findings to create a nomogram model. Patients with AAV-ILD who received treatment at the First Affiliated Hospital of Zhengzhou University during the period from March 1, 2011, to April 1, 2022 were selected for this research. The development of nomogram entailed a synergistic integration of univariate, Lasso, and multivariate Cox regression analyses. Internal validation ensued through bootstrap techniques involving 1000 re-sampling iterations. Discrimination and calibration were assessed utilizing Harrell's C-index, receiver operating characteristic (ROC) curve, and calibration curve. Model performance was evaluated through integrated discrimination improvement (IDI), net reclassification improvement (NRI), and likelihood ratio test. The net benefit of the model was evaluated using decision curve analysis (DCA). A cohort comprising 192 patients was enrolled for analysis. Throughout observation period, 32.29% of the population died. Key factors such as cardiac involvement, albumin, smoking history, and age displayed substantial prognostic relevance in AAV-ILD. These factors were incorporated to craft a predictive nomogram. Impressively, the model exhibited robust performance, boasting a Harrell's C index of 0.826 and an AUC of 0.940 (95% CI 0.904-0.976). The calibration curves depicted a high degree of harmony between predicted outcomes and actual observations. Significantly enhancing discriminative ability compared to the ILD-GAP model, the nomogram was validated through the IDI, NRI, and likelihood ratio test. DCA underscored the superior predictive value of the predictive model over the ILD-GAP model. The internal validation further affirmed this efficacy, with a mean Harrell's C-index of 0.815 for the predictive model. The nomogram model can be employed to predict the prognosis of patients with AAV-ILD. Moreover, the model performance is satisfactory. In the future, external datasets could be utilized for external validation.

Smoking cessation and vascular endothelial function

Smoking is associated with vascular endothelial dysfunction. It is thought that smoking impairs vascular endothelial function through a decrease in nitric oxide bioavailability induced by activation of oxidative stress and inflammation. Endothelial dysfunction can be improved or augmented by appropriate interventions including pharmacotherapy, administration of supplements and lifestyle modifications. Although there have not been many studies, the effects of smoking cessation on endothelial function have been shown. In those studies, it was shown that smoking cessation does not always have a positive effect on vascular endothelial function. In this review, I will focus on the role of smoking in endothelial function and the effects of smoking cessation on endothelial function. Smoking impairs vascular endothelial function and leads to atherosclerosis. Smoking cessation is expected to improve vascular endothelial function. Effects of smoking cessation on endothelial function are not always consistent. Further studies are needed to determine whether smoking cessation directly improves endothelial function. NO indicates nitric oxide.

Cigarette Smoke-Induced Reactive Oxygen Species Formation: A Concise Review

Smoking is recognized as a significant risk factor for numerous disorders, including cardiovascular diseases, respiratory conditions, and various forms of cancer. While the exact pathogenic mechanisms continue to be explored, the induction of oxidative stress via the production of excess reactive oxygen species (ROS) is widely accepted as a primary molecular event that predisposes individuals to these smoking-related ailments. This review focused on how cigarette smoke (CS) promotes ROS formation rather than the pathophysiological repercussions of ROS and oxidative stress. A comprehensive analysis of existing studies revealed the following key ways through which CS imposes ROS burden on biological systems: (1) ROS, as well as radicals, are intrinsically present in CS, (2) CS constituents generate ROS through chemical reactions with biomolecules, (3) CS stimulates cellular ROS sources to enhance production, and (4) CS disrupts the antioxidant system, aggravating the ROS generation and its functions. While the evidence supporting these mechanisms is chiefly based on in vitro and animal studies, the direct clinical relevance remains to be fully elucidated. Nevertheless, this understanding is fundamental for deciphering molecular events leading to oxidative stress and for developing intervention strategies to counter CS-induced oxidative stress.

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.

Nitric Oxide Synthase activity in major depressive episodes before and after antidepressant treatment: Results of a large case-control treatment study

BACKGROUND

Nitric oxide synthase (NOS) activity, an enzyme potentially involved in the major depressive episodes (MDE), could be indirectly measured by the L-Citrulline/L-Arginine ratio (L-Cit/L-Arg). The aim of this study was: (1) to compare the NOS activity of patients with a MDE to that of healthy controls (HC); (2) to assess its change after antidepressant treatment.

METHODS

A total of 460 patients with a current MDE in a context of major depressive disorder (MDD) were compared to 895 HC for NOS activity (L-Cit/L-Arg plasma ratio). L-Arg and L-Cit plasma levels were measured using a MS-based liquid chromatography method. Depressed patients were assessed at baseline, and after 3 and 6 months of antidepressant treatment for depression severity and clinical response.

RESULTS

Depressed patients had a lower NOS activity than HC at baseline [0.31 ± 0.09 v. 0.38 ± 0.12; 95% confidence interval (CI) -0.084 to -0.062, p < 0.0001]. Lower NOS activity at baseline predicted a higher response rate [odds ratio (OR) = 29.20; 95% CI 1.58-536.37; p = 0.023]. NOS activity in depressed patients increased significantly up to 0.34 ± 0.08 after antidepressant treatment (Est = 0.0034; 95% CI 0.0002-0.0067; p = 0.03).

CONCLUSIONS

Depressed patients have a decreased NOS activity that improves after antidepressant treatment and predicts drug response. NOS activity may be a promising biomarker for MDE in a context of MDD.

Smoking status and endothelial function in Japanese men

It is established that smoking is a major risk factor of atherosclerosis. Endothelial dysfunction occurs in the initial step in the pathogenesis of atherosclerosis and plays a critical role in the development of atherosclerosis. The purpose of this study was to evaluate the association between smoking status and endothelial function in detail in men. We measured flow-mediated vasodilation (FMD) in 2209 Japanese men including 1181 men who had never smoked and 1028 current smokers. All of the participants were divided into five groups by smoking pack-years: never smoker group (= 0), light smoker group (> 0 to 10), moderate smoker group (> 10 to 20), heavy smoker group (> 20 to 30) and excessive smoker group (> 30). FMD significantly decreased in relation to pack-years (6.6 ± 3.4% in the never smoker group, 6.8 ± 3.0% in the light smoker group, 6.5 ± 2.9% in the moderate smoker group, 5.9 ± 2.9% in the heavy smoker group, and 4.9 ± 2.7% in the excessive smoker group; P < 0.001). After adjustment for age (≥ 65 years), body mass index, systolic blood pressure, low-density lipoprotein cholesterol, glucose, and year of recruitment, FMD was significantly smaller in the excessive smoker group than in the never smoker group as a reference group (OR 1.95, 95% CI 1.42 to 2.67; P < 0.001). These findings suggest that FMD decreases with an increase in the number of cigarettes smoked and that excessive smoking is associated with endothelial dysfunction. Cigarette smoking is harmful to vascular function in men who are heavy smokers.

Acute Exposure to Environmental Tobacco Smoke: A Controlled Study in Adults with Asthma

BACKGROUND

Short-term, indoor exposure to environmental tobacco smoke (ETS) is still highly prevalent; however, little is known about the acute lung response in adult asthma.

OBJECTIVES

We investigated whether acute, experimental ETS exposure influences symptoms, lung function, and inflammatory parameters.

METHODS

Human subjects with asthma (n = 23) were exposed for 180 min to either room air or ETS at 250, 450, or 850 µg/m3. Respiratory symptoms, lung function, and exhaled nitric oxide (FeNO) were measured. Additionally, blood samples were analyzed for pro- and anti-inflammatory cytokines.

RESULTS

Humans with asthma demonstrate an increase in respiratory symptoms at all levels of ETS exposure, while the forced expiratory volume in 1 s (FEV1) and FeNO decrease with increasing ETS. The anti-inflammatory cytokine interleukin (IL)-10 increases at intermediate ETS concentrations, whereas tumor necrosis factor (TNF)-α and IL-8 increase only at the highest ETS concentration.

CONCLUSION

Following 180 min of acute, experimental ETS exposure, we observed a significant increase in respiratory symptoms, a decrease in lung function, and an increase in inflammatory cytokines, indicating an acute lung response in asthma.

Association of Cigarette Smoking With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

IMPORTANCE

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a systemic small vessel vasculitis characterized by circulating ANCAs targeting proteinase 3 (PR3) or myeloperoxidase (MPO) and associated with excess morbidity and mortality. Myeloperoxidase-ANCA-positive AAV and PR3-ANCA-positive AAV are increasingly recognized to have differences in genetic risk, pathogenesis, and response to treatment. Risk factors for AAV, including cigarette smoking, are poorly understood.

OBJECTIVE

To examine the association between cigarette smoking and AAV.

DESIGN, SETTING, AND PARTICIPANTS

This case-control study included a consecutive inception cohort of 484 patients with AAV diagnosed from 2002 to 2017 compared with a cohort of sex-, race-, and age-matched controls. Eleven cases were excluded owing to discordant smoking information in the electronic health record. Controls were randomly selected from participants recruited to the Partners HealthCare Biobank between its inception in 2010 and 2018 and who completed a smoking questionnaire and were not diagnosed with AAV (n = 30 536).

EXPOSURES

Smoking status (current, former, never) and pack-years of cigarette smoking were determined from review of the electronic medical record and smoking questionnaires.

MAIN OUTCOMES AND MEASURES

Patients with AAV were individually matched with 3 randomly-selected controls based on sex, race, and age (within 2 years difference). Conditional logistic regression was performed to examine the association between cigarette smoking and AAV using odds ratios (OR) and 95% confidence intervals (CIs).

RESULTS

Overall, 473 cases were matched with 1419 controls (mean [SD] age, 59 [16] years; 281 women [59%], 396 white [84%]). Patients with AAV were more likely to be former (OR, 1.6; 95% CI, 1.3-2.0) or current smokers (OR, 2.7; 95% CI, 1.8-4.1); there was a dose-response relationship according to pack-years of exposure (P < .001). These associations were especially strong among participants with MPO-ANCA-positive disease (former smokers: OR, 1.7; 95% CI, 1.3-2.3; current smokers: OR, 3.5; 95% CI, 2.1-6.1) but not in participants with PR3-ANCA-positive AAV (former smokers: OR, 1.3; 95% CI, 0.9-2.0; current smokers: OR, 1.7; 95% CI, 0.8-3.5). After stratifying by selected demographics and disease manifestations, these associations remained strong.

CONCLUSIONS AND RELEVANCE

Cigarette smoking was associated with AAV, especially MPO-ANCA-positive AAV. Further studies are needed to investigate a potential pathogenic mechanism.

The effect of endothelial nitric oxide synthase on the hemodynamics and wall mechanics in murine arteriovenous fistulas

Creation of a hemodialysis arteriovenous fistula (AVF) causes aberrant vascular mechanics at and near the AVF anastomosis. When inadequately regulated, these aberrant mechanical factors may impede AVF lumen expansion to cause AVF maturation failure, a significant clinical problem with no effective treatments. The endothelial nitric oxide synthase (NOS3) system is crucial for vascular health and function, but its effect on AVF maturation has not been fully characterized. We hypothesize that NOS3 promotes AVF maturation by regulating local vascular mechanics following AVF creation. Here we report the first MRI-based fluid-structure interaction (FSI) study in a murine AVF model using three mouse strains: NOS3 overexpression (NOS3 OE) and knockout (NOS3-/-) on C57BL/6 background, with C57BL/6 as the wild-type control (NOS3+/+). When compared to NOS3+/+ and NOS3-/-, AVFs in the OE mice had larger lumen area. AVFs in the OE mice also had smoother blood flow streamlines, as well as lower blood shear stress at the wall, blood vorticity, inner wall circumferential stretch, and radial wall thinning at the anastomosis. Our results demonstrate that overexpression of NOS3 resulted in distinct hemodynamic and wall mechanical profiles associated with favorable AVF remodeling. Enhancing NOS3 expression may be a potential therapeutic approach for promoting AVF maturation.

The effect of passive smoking on exhaled nitric oxide in asthmatic children

To date, some studies suggest that passive smoking (PS) may be an important determinant of FeNO levels in children but sill there is a need of investigations using objective methods of PS exposure. The aim of our study was to examine the effect of PS, measured by urine cotinine levels, on FeNO and lung function (FEV1) in allergic and non-allergic asthmatic children. METHODS: It was a prospective, non-interventional study. 140 children, aged 4-17, newly diagnosed with asthma were recruited into two study groups (exposed group, unexposed group), according to smoking exposure/unexposure based on the questionnaire. There was one study visit. Subjects underwent a medical history (including history of atopy), physical examination, spirometry, FeNO and urinary cotinine measurement. RESULTS: 70 individuals had been exposed to tobacco smoke. The patients exposed to tobacco smoke were characterized by statistically significantly higher urine concentration of cotinine, 10,80 ng/mL, than their counterparts who had not been exposed to tobacco smoke, 1,56 ng/mL (P = 0,019). In the group of individuals unexposed to tobacco smoke the mean value of FeNO was 34,99 ppb, while in the group of patient who had been exposed to tobacco smoke, the corresponding mean value was significantly lower, it amounted to 22,41 ppb (P = 0,001) (Table 1). As regards to FEV1 measurements, there were not any statistically significant differences by study groups unexposed/exposed to tobacco smoke (P = 0,179 and P = 0,074, respectively). FeNO levels (ppb) in the studied patients allergic to cat, grass or trees, exposed to tobacco smoke were significantly lower than in those children unexposed to tobacco smoke. Our results suggest a clinically important issue, that FeNO results should be interpreted in the context of environmental tobacco smoke exposure. Additionally allergy to cat dander, grass or tree may be potential confounding factor, which should be taken into consideration.

Modulation of Lung Function by Increased Nitric Oxide Production

INTRODUCTION

Cigarette smoking reduces endogenous Nitric Oxide (NO) production by reducing Nitric Oxide Synthase (NOS) activity, which is one of the probable reason for increased rate of pulmonary diseases in smokers. Nitric oxide/oxygen blends are used in critical care to promote capillary and pulmonary dilation to treat several pulmonary vascular diseases. Among several supplements, the highest NOS activation has been proved for garlic with its unique mechanism of action.

AIM

To investigate the effect of dietary supplementation of NO producing garlic on pulmonary function of smokers.

MATERIALS AND METHODS

The study was conducted on 40 healthy non-smoker (Group A) and 40 chronic smoker (Group B) males with matched age, height and weight. The pulmonary function tests- Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), FEV1/FVC ratio and Peak Expiratory Flow Rate (PEFR) were performed in non-smokers (Group A), smokers (Group B) and smokers after supplementation of approximately 4 gm of raw garlic (2 garlic cloves) per day for three months (Group C). Endogenous NO production was studied in smokers before and after garlic supplementation and in non-smokers without supplementation. The data obtained were compared between the groups using unpaired student's t-test. The p-value considered significant at <0.05.

RESULTS

Our results showed that FVC, FEV1, FEV1/FVC ratio and PEFR were reduced significantly along with a significant decreased NOS activity among smokers (Group B) when compared with non-smokers (Group A). Garlic supplementation significantly improved the pulmonary function tests in Group C in comparison to Group B by increasing NOS activity.

CONCLUSION

Dietary supplementation of garlic, which might be by increasing NOS activity, has significantly improved pulmonary functions in smokers.

Secondhand Smoking Is Associated With Vascular Inflammation

BACKGROUND

The relative risk for cardiovascular diseases in passive smokers is similar to that of active smokers despite almost a 100-fold lower dose of inhaled cigarette smoke. However, the mechanisms underlying the surprising susceptibility of the vascular tissue to the toxins in secondhand smoke (SHS) have not been directly investigated. The aim of this study was to investigate directly vascular endothelial cell function in passive smokers.

METHODS

Using a minimally invasive method of endothelial biopsy, we investigated directly the vascular endothelium in 23 healthy passive smokers, 25 healthy active smokers, and 23 healthy control subjects who had never smoked and had no regular exposure to SHS. Endothelial nitric oxide synthase (eNOS) function (expression of basal eNOS and activated eNOS [phosphorylated eNOS at serine1177 (P-eNOS)]) and expression of markers of inflammation (nuclear factor-κB [NF-κB]) and oxidative stress (nitrotyrosine) were assessed in freshly harvested venous endothelial cells by quantitative immunofluorescence.

RESULTS

Expression of eNOS and P-eNOS was similarly reduced and expression of NF-κB was similarly increased in passive and active smokers compared with control subjects. Expression of nitrotyrosine was greater in active smokers than control subjects and similar in passive and active smokers. Brachial artery flow-mediated dilation was similarly reduced in passive and active smokers compared with control subjects, consistent with reduced endothelial NO bioavailability.

CONCLUSIONS

Secondhand smoking increases vascular endothelial inflammation and reduces active eNOS to a similar extent as active cigarette smoking, indicating direct toxic effects of SHS on the vasculature.

Protective effect of melatonin on cigarette smoke-induced restenosis in rat carotid arteries after balloon injury

Vascular restenosis after the interventional angioplasty remains the main obstacle to a favorable long-term patency. Many researches suggest cigarette smoking is one of the most important causes of restenosis. This study was designed to investigate whether melatonin could protect against the cigarette smoke-induced restenosis in rat carotid arteries after balloon injury. Three groups of male rats (normal condition, cigarette smoke exposed, cigarette smoke exposed, and melatonin injected) were used in this study. An established balloon-induced carotid artery injury was performed, and the carotid arteries were harvested from these three groups 14 days later. The ratio of intima to media, the infiltration of inflammatory cells, the expression of inflammatory cytokines (NF-κB, IL-1β, IL-6, TNF-α, MCP-1), adhesion molecules (ICAM-1, VCAM-1), and eNOS were measured. The results showed that cigarette smoke exposure aggravated the stenosis of the lumen, promoted the infiltration of inflammatory cells and induced the expression of the inflammatory cytokines and adhesion molecules after the balloon-induced carotid artery injury. Moreover, cigarette smoke exposure can inhibit the expression of eNOS. Particularly, we surprised that melatonin could minimize this effect caused by cigarette smoke. These results suggested that melatonin could prevent the cigarette smoke-induced restenosis in rat carotid arteries after balloon injury and the mechanism of its protective effect may be the inhibition of the inflammatory reaction. This also implies melatonin has the potential therapeutic applicability in prevention of restenosis after the vascular angioplasty in smokers.

Association of the genetic variants of endothelial nitric oxide synthase gene with angiographically defined coronary artery disease and myocardial infarction in South Indian patients with type 2 diabetes mellitus

INTRODUCTION

The polymorphic variants of endothelial nitric oxide synthase (eNOS) gene have been implicated in endothelial dysfunction and are highly relevant to macroangiopathies. We investigated the relationship between eNOS gene T-786C, G894T, intron 4a/b polymorphisms and coronary artery disease (CAD) in South Indian type 2 diabetic (T2DM) individuals.

METHODS

We screened 283 T2DM patients, inclusive of 160 with angiographically defined CAD, 73 with myocardial infarction (MI), 89 without MI and 121 T2DM individuals with no evidence of CAD for eNOS gene polymorphisms.

RESULTS

There appeared to be a significant difference in the genotype and allele distribution of eNOS T-786C polymorphism between T2DM groups with and without CAD (p=0.004), albeit no significant association with MI was observed. The frequencies of TC and CC genotypes and -786C allele were considerably higher in patients with triple vessel disease (TVD) as compared to those without CAD (p=0.003), thereby associating this polymorphism with severity of CAD. Genotype and allele distributions of G894T and intron 4a/b polymorphisms were not significantly different between T2DM subjects with and without CAD/MI. Significant linkage disequilibrium was observed between intron 4a/b and T-786C polymorphisms. Multiple logistic regression analysis revealed a significant and independent association of eNOS T-786C polymorphism and other putative risk factors with CAD/TVD in T2DM individuals.

CONCLUSIONS

These findings reveal a significant association between eNOS T-786C polymorphism, CAD/TVD and coincident putative risk factors in T2DM individuals in South Indian population.

Cigarette smoke and adverse health effects: An overview of research trends and future needs

A large volume of data has accumulated on the issues of tobacco and health worldwide. The relationship between tobacco use and health stems initially from clinical observations about lung cancer, the first disease definitively linked to tobacco use. Almost 35 years ago, the Office of the Surgeon General of the United States Health Service reviewed over 7000 research papers on the topic of smoking and health, and publicly recognized the role of smoking in various diseases, including lung cancer. Since then, numerous studies have been published that substantiate the strong association of tobacco use with a variety of adverse human health effects, most prominently with cancer and cardiovascular diseases. Cigarette smoking is regarded as a major risk factor in the development of lung cancer, which is the main cause of cancer deaths in men and women in the United States and the world. Major advances have been made by applying modern genetic technologies to examine the relationship between exposure to tobacco smoke and the development of diseases in human populations. The present review summarizes the major research areas of the past decade, important advances, future research needs and federal funding trends.

The value of exhaled nitric oxide to identify asthma in smoking patients with asthma-like symptoms

BACKGROUND

The fraction of nitric oxide in exhaled air (FeNO) is used in asthma diagnosis and management. Smoking reduces FeNO and 20-35% of asthmatics are smoking. However no guidelines exist on the diagnostic value of FeNO in smokers. Therefore we assessed the value of FeNO to diagnose asthma in a population of subjects with asthma-like symptoms and different smoking habits.

METHODS

Measurements of FeNO, lung function, bronchial responsiveness and allergy testing were performed in 282 subjects (108 never-, 62 ex- and 112 current smokers) aged 14-44 years, with symptoms suggestive of asthma. These subjects were a subset of subjects reporting respiratory symptoms (n = 686) in a random population sample (n = 10,400).

RESULTS

A diagnosis of asthma was given to 96 of the 282 subjects. Subjects with asthma had higher FeNO levels than subjects with non-specific asthma symptoms in all three smoking strata (p < 0.001), with a percentual increase of FeNO by 76% in never-, 71% in ex- and 60% in current smokers. The area under the ROC-curve was similar in never-, ex- and current smokers (0.72 vs. 0.74 vs. 0.70). The cut-offs were approximately 30% lower for either 90% specificity (22 vs. 31 ppb) or 90% sensitivity (7 vs. 10 ppb) in current vs. never-smokers.

CONCLUSIONS

FeNO could differentiate asthmatic subjects from non-asthmatic subjects with asthma-like symptoms equally well in both never- and current smokers within a random population sample. The FeNO cut-off levels needed in order to achieve high sensitivity or specificity were lower in current smokers.

Tetrahydrobiopterin: biochemistry and pathophysiology

BH4 (6R-L-erythro-5,6,7,8-tetrahydrobiopterin) is an essential cofactor of a set of enzymes that are of central metabolic importance, including four aromatic amino acid hydroxylases, alkylglycerol mono-oxygenase and three NOS (NO synthase) isoenzymes. Consequently, BH4 is present in probably every cell or tissue of higher organisms and plays a key role in a number of biological processes and pathological states associated with monoamine neurotransmitter formation, cardiovascular and endothelial dysfunction, the immune response and pain sensitivity. BH4 is formed de novo from GTP via a sequence of three enzymatic steps carried out by GTP cyclohydrolase I, 6-pyruvoyltetrahydropterin synthase and sepiapterin reductase. An alternative or salvage pathway involves dihydrofolate reductase and may play an essential role in peripheral tissues. Cofactor regeneration requires pterin-4a-carbinolamine dehydratase and dihydropteridine reductase, except for NOSs, in which the BH4 cofactor undergoes a one-electron redox cycle without the need for additional regeneration enzymes. With regard to the regulation of cofactor biosynthesis, the major controlling point is GTP cyclohydrolase I. BH4 biosynthesis is controlled in mammals by hormones and cytokines. BH4 deficiency due to autosomal recessive mutations in all enzymes, except for sepiapterin reductase, has been described as a cause of hyperphenylalaninaemia. A major contributor to vascular dysfunction associated with hypertension, ischaemic reperfusion injury, diabetes and others, appears to be an effect of oxidized BH4, which leads to an increased formation of oxygen-derived radicals instead of NO by decoupled NOS. Furthermore, several neurological diseases have been suggested to be a consequence of restricted cofactor availability, and oral cofactor replacement therapy to stabilize mutant phenylalanine hydroxylase in the BH4-responsive type of hyperphenylalaninaemia has an advantageous effect on pathological phenylalanine levels in patients.

Nitric oxide-mediated blood flow regulation as affected by smoking and nicotine

Cigarette smoking is a major risk factor for atherosclerosis, cerebral and coronary vascular diseases, hypertension, and diabetes mellitus. Chronic smoking impairs endothelial function by decreasing the formation of nitric oxide and increasing the degradation of nitric oxide via generation of oxygen free radicals. Nitric oxide liberated from efferent nitrergic nerves is also involved in vasodilatation, increased regional blood flow, and hypotension that are impaired through nitric oxide sequestering by smoking-induced factors. Influence of smoking on nitric oxide-induced blood flow regulation is not necessarily the same in all organs and tissues. However, human studies are limited mainly to the forearm blood flow measurement that assesses endothelial function under basal and stimulated conditions and also determination of penile tumescence and erection in response to endothelial and neuronal nitric oxide. Therefore, information about blood flow regulation in other organs, such as the brain and placenta, has been provided mainly from studies on experimental animals. Nicotine, a major constituent of cigarette smoke, acutely dilates cerebral arteries and arterioles through nitric oxide liberated from nitrergic neurons, but chronically interferes with endothelial function in various vasculatures, both being noted in studies on experimental animals. Cigarette smoke constituents other than nicotine also have some vascular actions. Not only active but also passive smoking is undoubtedly harmful for both the smokers themselves and their neighbors, who should bear in mind that they can face serious diseases in the future, which may result in lengthy hospitalization, and a shortened lifespan.

Risk factors for lower-extremity vein graft failure

Lower-extremity vein graft failure causes significant morbidity, increases health care costs, and negatively impacts patient quality of life. Identification of risk factors is essential for patient selection, risk factor modification, and identifying individuals who would benefit from more stringent surveillance protocols. Risk factors can be considered as either patient-related or technical. Here we discuss the patient-related risk factors for vein graft failure. Nontechnical factors related to the indication for operation include operation after a previously failed graft, or redo bypass, critical limb ischemia, and infection. Risk factors for vein graft failure are distinct from the risk factors for cardiovascular events. Young age and African American and Hispanic race are risk factors for lower-extremity vein graft failure. Hypercoaguable and inflammatory states also increase risk for vein graft failure. Therapy with statins is indicated in patients with peripheral atherosclerosis and may have beneficial effects on vein graft function, although further studies are needed in this area.

Regulation of endothelial cell tetrahydrobiopterin pathophysiological and therapeutic implications

Tetrahydrobiopterin (BH(4)) is a critical cofactor for the nitric oxide synthases. In the absence of BH(4), these enzymes become uncoupled, fail to produce nitric oxide, and begin to produce superoxide and other reactive oxygen species (ROS). BH(4) levels are modulated by a complex biosynthetic pathway, salvage enzymes, and by oxidative degradation. The enzyme GTP cyclohydrolase-1 catalyzes the first step in the de novo synthesis of BH(4) and new evidence shows that this enzyme is regulated by phosphorylation, which reduces its interaction with its feedback regulatory protein (GFRP). In the setting of a variety of common diseases, such as atherosclerosis, hypertension, and diabetes, reactive oxygen species promote oxidation of BH(4) and inhibit expression of the salvage enzyme dihydrofolate reductase (DHFR), promoting accumulation of BH(2) and NOS uncoupling. There is substantial interest in therapeutic approaches to increasing tissue levels of BH(4), largely by oral administration of this agent. BH(4) treatment has proved effective in decreasing atherosclerosis, reducing blood pressure, and preventing complications of diabetes in experimental animals. While these basic studies have been very promising, there are only a few studies showing any effect of BH(4) therapy in humans in treatment of these common problems. Whether BH(4) or related agents will be useful in treatment of human diseases needs additional study.

GTP cyclohydrolase I expression is regulated by nitric oxide: role of cyclic AMP

Our previous studies have demonstrated that nitric oxide (NO) leads to nitric oxide synthase (NOS) uncoupling and an increase in NOS-derived superoxide. However, the cause of this uncoupling has not been adequately resolved. The pteridine cofactor tetrahydrobiopterin (BH(4)) is a critical determinant of endothelial NOS (eNOS) activity and coupling, and GTP cyclohydrolase I (GCH1) is the rate-limiting enzyme in its generation. Thus the initial purpose of this study was to determine whether decreases in BH(4) could underlie, at least in part, the NO-mediated uncoupling of eNOS we have observed both in vitro and in vivo. Initially we evaluated the effect of inhaled NO levels on GCH1 expression and BH(4) levels in the intact lamb. Contrary to our hypothesis, we found that there was a significant increase in both plasma BH4 levels and peripheral lung GCH1 protein levels. Furthermore, in vitro, we found that exposure to the NO donor spermine NONOate (SPNONO) led to an increase in GCH1 protein and BH(4) levels in both COS-7 and pulmonary arterial endothelial cells. However, SPNONO treatment also caused a significant increase in phospho-cAMP response element binding protein (CREB) levels, as detected by Western blot analysis, and significantly increased cAMP levels, as detected by enzyme immunoassay. Furthermore, utilizing GCH1 promoter fragments fused to a luciferase reporter gene, we found that GCH1 promoter activity was enhanced by SPNONO in a CREB-dependent manner, and electromobility shift assays revealed an NO-dependent increase in the nuclear binding of CREB. These data suggest that NO increases BH(4) levels through a cAMP/CREB-mediated increase in GCH1 transcription and that the eNOS uncoupling associated with exogenous NO does not involved reduced BH(4) levels.

Excessive nitric oxide function and blood pressure regulation in patients with autonomic failure

Approximately 50% of patients with autonomic failure (AF) suffer from supine hypertension, even those with very low plasma norepinephrine and renin. Because NO is arguably the most potent metabolic modulator of blood pressure, we hypothesized that impaired NO function contributes to supine hypertension in AF. However, we found that AF patients (n=14) were more sensitive to the pressor effects of the NO synthase inhibitor N(G)-monomethyl-l-arginine, suggesting increased NO function rather than deficiency; a lower dose of N(G)-monomethyl-l-arginine was needed to produce a similar increase in blood pressure in AF patients, as in healthy control subjects in whom AF was induced with the ganglionic blocker trimethaphan (171+/-37 mg versus 512+/-81 mg, respectively; P=0.001). Furthermore, potentiation of the actions of endogenous NO with the phosphodiesterase inhibitor sildenafil (25 mg PO) decreased nighttime supine systolic blood pressure from 182+/-11 to 138+/-4 mm Hg in 8 AF patients with supine hypertension (P=0.012 compared with placebo). Finally, AF patients tolerated a greater degree of upright tilt during infusion of N(G)-monomethyl-l-arginine (56+/-6 degrees versus 41+/-4 degrees with placebo; n=7; P=0.014), an improvement in orthostatic tolerance similar to that obtained with equipressor doses of phenylephrine. In conclusion, AF patients do not have NO deficiency contributing to supine hypertension. Instead, they have increased NO function contributing to their orthostatic hypotension. Potentiation of NO could be used in the treatment of supine hypertension, and its inhibition offers a novel approach to improve orthostatic hypotension.

Cigarette smoking and erectile dysfunction: focus on NO bioavailability and ROS generation

INTRODUCTION

Thirty million men in the United States suffer from erectile dysfunction (ED) and this number is expected to double by 2025. Considered a major public health problem, which seriously affects the quality of life of patients and their partners, ED becomes increasingly prevalent with age and chronic smoking is a major risk factor in the development of ED.

AIM

To review available evidence concerning the effects of cigarette smoking on vascular changes associated with decreased nitric oxide (NO) bioavailability and increased reactive oxygen species (ROS) generation.

METHODS

We examined epidemiological and clinical data linking cigarette smoking and ED, and the effects of smoking on vascular NO bioavailability and ROS generation.

MAIN OUTCOME MEASURES

There are strong parallels between smoking and ED and considerable evidence supporting the concept that smoking-related ED is associated with reduced bioavailability of NO because of increased ROS.

RESULTS

Cigarette smoking-induced ED in human and animal models is associated with impaired arterial flow to the penis or acute vasospasm of the penile arteries. Long-term smoking produces detrimental effects on the vascular endothelium and peripheral nerves and also causes ultrastructural damage to the corporal tissue, all considered to play a role in chronic smoking-induced ED. Clinical and basic science studies provide strong indirect evidence that smoking may affect penile erection by the impairment of endothelium-dependent smooth muscle relaxation or more specifically by affecting NO production via increased ROS generation. Whether nicotine or other products of cigarette smoke mediate all effects related to vascular damage is still unknown.

CONCLUSIONS

Smoking prevention represents an important approach for reducing the risk of ED. The characterization of the components of cigarette smoke leading to ED and the mechanisms by which these components alter signaling pathways activated in erectile responses are necessary for a complete comprehension of cigarette smoking-associated ED.

Vascular endothelial function in health and diseases

The vascular endothelium constitutes approximately 1% of body mass (1kg) and has a surface area of approximately 5000m(2). The endothelium is a multifunctional endocrine organ strategically placed between the vessel wall and the circulating blood, and has a key role in vascular homeostasis. The endothelium is both a target for and mediator of cardiovascular disease. The endothelium releases several relaxing and constricting factors, which can affect vascular homeostasis. Endothelial dysfunction, whether caused by physical injury or cellular damage, leads to compensatory responses that alter the normal homeostatic properties of the endothelium. In this review, we summarized some physiological aspects of endothelial function and then we discussed endothelial dysfunction during some pathological conditions.

Do lifestyle changes work for improving erectile dysfunction?

The main cause of erectile dysfunction (ED) is organic in nature, with vascular etiologies being the most common risk factors. Although there have been sufficient data on the relationship between ED and several well-recognized risk factors, including aging, coronary artery disease, atherosclerosis, diabetes mellitus, dyslipidemia, high blood pressure, and pelvic surgeries, little attention has been paid by the urologists to the role of lifestyle factors in ED. However, accumulating data from basic science and clinical studies have determined a link between the occurrence of ED and a number of lifestyle factors, such as smoking, obesity, alcohol consumption, and lack of physical activity. The application of findings from animal and human studies to the clinical practice regarding the modification of lifestyle factors could help improving ED as well as reducing the risks of developing cardiovascular diseases. This communication addresses the impact of lifestyle factors on erectile function and the potential benefits of modifying these factors to improve ED in respect to the current evidence.

Ratio of 5,6,7,8-tetrahydrobiopterin to 7,8-dihydrobiopterin in endothelial cells determines glucose-elicited changes in NO vs. superoxide production by eNOS

5,6,7,8-Tetrahydrobiopterin (BH(4)) is an essential cofactor of nitric oxide synthases (NOSs). Oxidation of BH(4), in the setting of diabetes and other chronic vasoinflammatory conditions, can cause cofactor insufficiency and uncoupling of endothelial NOS (eNOS), manifest by a switch from nitric oxide (NO) to superoxide production. Here we tested the hypothesis that eNOS uncoupling is not simply a consequence of BH(4) insufficiency, but rather results from a diminished ratio of BH(4) vs. its catalytically incompetent oxidation product, 7,8-dihydrobiopterin (BH(2)). In support of this hypothesis, [(3)H]BH(4) binding studies revealed that BH(4) and BH(2) bind eNOS with equal affinity (K(d) approximately 80 nM) and BH(2) can rapidly and efficiently replace BH(4) in preformed eNOS-BH(4) complexes. Whereas the total biopterin pool of murine endothelial cells (ECs) was unaffected by 48-h exposure to diabetic glucose levels (30 mM), BH(2) levels increased from undetectable to 40% of total biopterin. This BH(2) accumulation was associated with diminished calcium ionophore-evoked NO activity and accelerated superoxide production. Since superoxide production was suppressed by NOS inhibitor treatment, eNOS was implicated as a principal superoxide source. Importantly, BH(4) supplementation of ECs (in low and high glucose-containing media) revealed that calcium ionophore-evoked NO bioactivity correlates with intracellular BH(4):BH(2) and not absolute intracellular levels of BH(4). Reciprocally, superoxide production was found to negatively correlate with intracellular BH(4):BH(2). Hyperglycemia-associated BH(4) oxidation and NO insufficiency was recapitulated in vivo, in the Zucker diabetic fatty rat model of type 2 diabetes. Together, these findings implicate diminished intracellular BH(4):BH(2), rather than BH(4) depletion per se, as the molecular trigger for NO insufficiency in diabetes.

Reproducibility of exhaled nitric oxide in smokers and non-smokers: relevance for longitudinal studies

Background

Currently, there is much interest in measuring fractional exhaled nitric oxide (FE_NO) in populations. We evaluated the reproducibility of FE_NO in healthy subjects and determined the number of subjects necessary to carry out a longitudinal survey of FE_NO in a population containing smokers and non-smokers, based on the assessed reproducibility.

Methods

The reproducibility of FE_NO was examined in 18 healthy smokers and 21 non-smokers. FE_NO was assessed once at 9 AM on five consecutive days; in the last day this measurement was repeated at 2 PM. Respiratory symptoms and medical history were assessed by questionnaire. The within- and between-session repeatability of FE_NO and log-transformed FE_NO was described. The power of a longitudinal study based on a relative increase in FE_NO was estimated using a bilateral t-test of the log-transformed FE_NO using the between-session variance of the assay.

Results

FE_NO measurements were highly reproducible throughout the study. FE_NO was significantly higher in males than females regardless of smoking status. FE_NO was positively associated with height (p < 0.001), gender (p < 0.034), smoking (p < 0.0001) and percent FEV₁/FVC (p < 0.001) but not with age (p = 0.987). The between-session standard deviation was roughly constant on the log scale. Assuming the between-session standard deviation is equal to its longitudinal equivalent, either 111 or 29 subjects would be necessary to achieve an 80% power in detecting a 3% or a 10% increase in FE_NO respectively.

Conclusion

The good reproducibility of FE_NO is not influenced by gender or smoking habits. In a well controlled, longitudinal study it should allow detecting even small increases in FE_NO with a reasonable population size.

Nitric oxide pathways and evidence-based perturbations in acute pancreatitis

Nitric oxide (NO) is a gaseous neurotransmitter, a vasodilator and paracrine regulator. In the pancreas, NO regulates normal pancreatic exocrine secretion, endocrine pancreatic insulin secretion and pancreatic microvascular blood flow. NO has multiple species and is produced de novo by 3 NO synthase enzymes. Endothelial NO synthase reduces the severity of the initial phase of experimental acute pancreatitis (AP). Cigarette smoking and chronic alcohol use disrupt normal NO pathways and are associated with pancreatitis and pancreatic cancer. The aims of this minireview are to describe normal intrapancreatic NO pathways, perturbations during experimental AP and due to epidemiological factors associated with pancreatic pathology, and the clinical implications of NO on AP.

Oxygen metabolism by endothelial nitric-oxide synthase

Nitric-oxide synthase (NOS) catalyzes both coupled and uncoupled reactions that generate nitric oxide and reactive oxygen species. Oxygen is often the overlooked substrate, and the oxygen metabolism catalyzed by NOS has been poorly defined. In this paper we focus on the oxygen stoichiometry and effects of substrate/cofactor binding on the endothelial NOS isoform (eNOS). In the presence of both L-arginine and tetrahydrobiopterin, eNOS is highly coupled (>90%), and the measured stoichiometry of O(2)/NADPH is very close to the theoretical value. We report for the first time that the presence of L-arginine stimulates oxygen uptake by eNOS. The fact that nonhydrolyzable L-arginine analogs are not stimulatory indicates that the occurrence of the coupled reaction, rather than the accelerated uncoupled reaction, is responsible for the L-arginine-dependent stimulation. The presence of 5,6,7,8-tetrahydrobiopterin quenched the uncoupled reactions and resulted in much less reactive oxygen species formation, whereas the presence of redox-incompetent 7,8-dihydrobiopterin demonstrates little quenching effect. These results reveal different mechanisms for oxygen metabolism for eNOS as opposed to nNOS and, perhaps, partially explain their functional differences.

Pioglitazone reverses insulin resistance and impaired CCK-stimulated pancreatic secretion in eNOS(-/-) mice: therapy for exocrine pancreatic disorders?

In mice, eNOS (endothelial nitric oxide synthase) maintains in vivo pancreatic secretory responses to carbachol or cholecystokinin octapeptide (CCK-8), maintains insulin sensitivity, and modulates pancreatic microvascular blood flow (PMBF). eNOS(-/-) mice are insulin resistant, and their exocrine pancreatic secretion is impaired. We hypothesized that the reduced exocrine pancreatic secretion in eNOS(-/-) mice is due to insulin resistance or impaired PMBF. To test this hypothesis, we gave eNOS(-/-) and wild-type (WT) mice pioglitazone (20 or 50 mg.kg(-1).day(-1)), an insulin-sensitizing peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activator, and measured pancreatic protein secretion evoked by CCK-8 (160 pmol.kg(-1).h(-1), a maximal stimulus). We also measured insulin resistance, serum glucose, C-peptide, insulin, pancreatic RNA digestive enzyme expression, and PMBF (microsphere technique). In WT mice, pioglitazone did not increase CCK-8-stimulated protein output over baseline. In eNOS(-/-) mice, however, pioglitazone substantially increased the low CCK-8-stimulated protein output that is characteristic of these mutant mice (P < 0.005). Pioglitazone abolished the CCK-8-evoked hyperinsulinemia (P < 0.005) and increased insulin sensitivity of eNOS(-/-) mice (P < 0.05), the latter based on hyperinsulinemic-euglycemic clamp studies. Pioglitazone had no effect on PMBF or pancreas mRNA expression of insulin or digestive enzymes. We conclude that in hyperinsulinemic eNOS(-/-) mice, a nonobese model of insulin resistance relevant to diabetes mellitus and possibly chronic pancreatitis, reduced pancreatic secretion is caused, at least in part, by insulin resistance. Insulin-sensitizing PPAR-gamma agonists such as pioglitazone may thus simultaneously correct endocrine and exocrine pancreatic disorders.

Increased vascular contractility in isolated vessels from cigarette smoking rats is mediated by basal endothelin release

The effect of chronic cigarette smoking on endothelin modulation of vascular contraction, and CYP enzyme levels was studied in 20 male Sprague-Dawley rats. The animals were divided equally into smoking and non-smoking groups. The smoking group was exposed to 6 research cigarettes per rat per day 5 days a week for 16 weeks. The control group was sham smoked. Functional contractile studies were performed in aortas and carotid arteries to determine the regulation of vascular tone by basal release of endothelin. Liver samples were analyzed for CYP1A1 and CYP1A2 gene expression by RT-PCR. Plasma samples were assessed for endothelin-1 (ET-1) level by enzyme immuno assay (EIA). Treatment of aortas and carotid arteries with bosentan, the dual endothelin receptor antagonist, caused a significant reduction in constrictor responses of smoking rats, indicating, increase greater regulation of tone by endothelin in smoker rats compared to controls. There was a greater expression of the cytochrome P450-liver enzymes (CYP1A1 and CYP1A2) in smoker rats. Body weight gain was also significantly decreased in smoker rats. We conclude that increased endothelin release in smoker rats significantly contributes to increased arterial tone and so contribute to the cardiovascular pathophysiology associated with cigarette smoking, such as increased vascular muscularization, increased contraction, decreased dilation and possibly vasospasm.

Promoter polymorphism (-786t>C) in the endothelial nitric oxide synthase gene is associated with risk of sporadic breast cancer in non-Hispanic white women age younger than 55 years

BACKGROUND

Nitric oxide (NO) is constitutively synthesized in the endothelium by endothelial nitric oxide synthase (eNOS) and acts as a pleiotropic regulator involved in carcinogenesis. Most breast cancers develop from mammary epithelial cells; therefore, NO may play a role in their development. It was hypothesized that eNOS polymorphisms are associated with risk of breast cancer.

METHODS

In the current hospital-based case-control study of 421 non-Hispanic white women with sporadic breast cancer and 423 frequency-matched control subjects, we genotyped 3 polymorphisms of eNOS (i.e., -786T>C, the 27-base pair [bp] variable number of tandem repeats [VNTR] in intron 4, and 894G>T [Glu298Asp]) and assessed their associations with risk of breast cancer.

RESULTS

It was found that, compared with -786TT, the -786C variant genotypes were associated with a significantly increased risk of breast cancer in an allele dose-dependent manner (adjusted odds ratio [OR], 1.33 [95% confidence interval (95% CI)], 0.99-1.77 for -786TC; and OR, 1.79 [95% CI, 1.11-2.87] for -786CC; P(trend) = .007), but 27-bp VNTR and 894G>T genotypes were not. Stratification analysis demonstrated that the risk associated with -786C variant genotypes (-786TC/CC) was more pronounced in smokers and in those 50 years or older (OR, 1.82 [95% CI, 1.19-2.80] and OR, 2.08 [95% CI, 1.25-3.45], respectively), and in the estrogen and progesterone receptor-negative cases (OR, 1.70 [95% CI, 1.10-2.62] and OR, 1.57 [95% CI, 1.07-2.32], respectively). Furthermore, the C4G haplotype derived from the observed genotypes was also associated with a significantly increased risk of breast cancer (OR, 2.16; 95% CI, 1.07-4.36).

CONCLUSIONS

The results suggest that eNOS polymorphisms (especially -786T>C) may play a role in the development of sporadic breast cancer.

Effect of cigarette smoking on nitric oxide, structural, and mechanical properties of mouse arteries

Cigarette smoking (CS) is a major risk factor for vascular disease. The aim of this study was to quantitatively assess the influence of CS on mouse arteries. We studied the effect of short-term (6 wk) and long-term (16 wk) CS exposure on structural and mechanical properties of coronary arteries compared with that of control mice. We also examined the reversibility of the deleterious effects of CS on structural [e.g., wall thickness (WT)], mechanical (e.g., stiffness), and biochemical [e.g., nitric oxide (NO) by-products] properties with the cessation of CS. The left and right coronary arteries were cannulated in situ and mechanically distended. The stress, strain, elastic modulus, and WT of coronary arteries were determined. Western blot analysis was used to analyze endothelial NO synthase (eNOS) in the femoral and carotid arteries of the same mice, and NO by-products were determined by measuring the levels of nitrite. Our results show that the mean arterial pressure was increased by CS. Furthermore, CS significantly increased the elastic modulus, decreased stress and strain, and increased the WT and WT-to-radius ratio compared with those of control mice. The reduction of eNOS protein expression was found only after long-term CS exposure. Moreover, the NO metabolite was markedly decreased in CS mice after short- and long-term exposure of CS. These findings suggest that 16 wk of CS exposure can cause an irreversible deterioration of structural and elastic properties of mouse coronary arteries. The decrease in endothelium-derived NO in CS mice was seen to significantly correlate with the remodeling of arterial wall.

Tetrahydrobiopterin improves aging-related impairment of endothelium-dependent vasodilation through increase in nitric oxide production

Deficiency of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide (NO) synthase, decreases NO production and increases reactive oxygen species. The purpose of this study was to elucidate the effects of aging on endothelial function and to determine whether the degree of BH4 deficiency is related to aging and oxidative stress. We evaluated forearm blood flow (FBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and isosorbide dinitrate (ISDN), an endothelium-independent vasodilator, before and after co-infusion of BH4 (500 mg/min) in 37 healthy men (mean age, 41+/-18 yr; range, 19-81 yr). FBF was measured using strain-gauge plethysmograph. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and serum malondialdehyde-modified low-density lipoprotein (MDA-LDL) were measured as indices of oxidative stress. Both ACh and ISDN increased the FBF in a dose-dependent manner in all subjects. Co-infusion of BH4 resulted in a significant increase in ACh-induced vasodilation (from 22.3+/-6.7 to 30.1+/-7.5 mL/min/100 mL tissue, P<0.05). Aging was found to be significantly correlated with ACh-induced vasodilation (r=-0.47, P=0.006), urinary 8-OHdG (r=0.38, P=0.02), serum MDA-LDL (r=0.36, P=0.02), and the change in ACh-induced vasodilation after co-infusion of BH4 (r=0.45, P=0.007). The FBF response to ISDN did not correlate with any parameters. Infusion of N(G)-monomethyl-L-arginine, an NO synthase inhibitor, abolished the BH4-induced enhancement of forearm vasorelaxation evoked by ACh. The increase in FBF after ISDN was not altered by BH4. These findings suggest that a deficiency of BH4 may be involved in the pathogenesis of disturbances in endothelium-dependent vasodilation related to aging through decrease in NO production and increase in oxidative stress.

Smoking-gene interaction and disease development: relevance to pancreatic cancer and atherosclerosis

There is little doubt that cigarette smoking remains a major environmental health risk that humans are facing in the twenty-first century. Cigarette smokers are more likely to develop many forms of diseases than nonsmokers, including cancers and vascular diseases. With the availability of the human genome sequence, we become more aware of the genetic contributions to these common diseases, especially the interactive relations between environmental factors (e.g., smoking) and genes on disease susceptibility, development, and prognosis. Although smoking is responsible for up to 30% of pancreatic cancers and about 10% of cases are ascribed to genetic reasons, some genetic variants do not predispose carriers to disease development unless they are exposed to a specific adverse environment such as smoking. This smoke-gene interaction could potentially be responsible for most of the cases. Certain polymorphisms in genes such as CYP1A1 have been shown particularly sensitive to smoking-induced pathogenesis, including pancreatic cancer and atherosclerosis. We found that individuals with CYP1A1 CC genotype had a more than three fold increase in risk for severe coronary atherosclerosis when they smoked. Patients with endothelial nitric oxide synthase (eNOS) intron 4 27 repeat homozygotes were more likely to develop severe coronary stenosis when they smoked. On the other hand, DNA variants at the eNOS gene also dictate how smoking affects the expression of eNOS. We showed that GSTM1 deficiency was not involved in smoking-induced vascular diseases, but p53 polymorphisms tended to modify the disease severity in smokers. We are still at an early stage of defining the pairs and mechanisms of smoke-gene interaction, and this etiologic mechanism may hold great potential for risk assessment, treatment strategy, and prognostic predictions.

Studies on microbiological degradation of tobacco tar

A bacterium, strain MR4, was isolated from tobacco tar-contaminated soil and identified as Klebsiella oxytoca based on morphology, physiological and biochemical characteristics and phylogenetic analysis of 16S rDNA sequence. The organism grew optimally at 34 degrees C and pH 7.0 to 7.5. During growth on tobacco tar the isolate produced acid materials, which caused the drop of pH in the cultures. GC/MS analysis indicated that the isolate had the ability to degrade phenolic compounds, heterocyclic compounds, especially nicotine in tobacco tar. The degradation rate of strain MR4 was 75.56% for nicotine, 35.84% to 58.16% for hydroxybenzenes and the other aromatic compounds, 29.15% to 65.56% for heterocyclics, and 35.17% to 82.59% for hydrocarbons.

Time-dependent inhibition and tetrahydrobiopterin depletion of endothelial nitric-oxide synthase caused by cigarettes

Smoking causes a dysfunction in endothelial nitric-oxide synthase (eNOS), which is ameliorated, in part, by administration of tetrahydrobiopterin (BH(4)). The exact mechanism by which the nitric oxide deficit occurs is unknown. We have previously shown that aqueous extracts of chemicals in cigarettes (CE) cause the suicide inactivation of neuronal NO synthase (nNOS) by interacting at the substrate-binding site. In the current study, we have found that CE directly inactivates eNOS by a process that is not affected by the natural substrate l-arginine and is distinct from the mechanism of inactivation of nNOS. We discovered that CE causes a time-, concentration-, and NADPH-dependent inactivation of eNOS in an in vitro system containing the purified enzyme, indicating a metabolic component to the inactivation. The CE-treated eNOS but not nNOS was nearly fully reactivated upon incubation with excess BH(4), suggesting that BH(4) depletion is a potential mechanism of inactivation. Moreover, in the presence of CE, eNOS catalyzed the oxidation of BH(4) to dihydrobiopterin and biopterin by a process attenuated by high concentrations of superoxide dismutase but not catalase. We speculate that a redox active component in CE, perhaps a quinone compound, causes oxidative uncoupling of eNOS to form superoxide, which in turn oxidizes BH(4). The discovery of a direct inactivation of eNOS by a compound(s) present in tobacco provides a basis not only for further study of the mechanisms responsible for the biological effects of tobacco but also a search for a potentially novel inactivator of eNOS.

Mechanisms of aging-induced impairment of endothelium-dependent relaxation: role of tetrahydrobiopterin

Oxidative stress has been implicated as an important mechanism of vascular endothelial dysfunction induced by aging. Previous studies suggested that tetrahydrobiopterin (BH4), an essential cofactor of endothelial NO synthase, could be a molecular target for oxidation. We tested the hypothesis that oxidative stress, in particular oxidation of BH4, may contribute to attenuation of endothelium-dependent relaxation in aged mice. Vasomotor function of isolated carotid arteries was studied using a video dimension analyzer. Vascular levels of BH4 and its oxidation products were measured via HPLC. In aged mice (age, 95 +/- 2 wk), endothelium-dependent relaxation to ACh (10(-5) to 10(-9) M) as well as endothelium-independent relaxation to the NO donor diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate, 10(-5) to 10(-9) M) were significantly reduced compared with relaxation detected in young mice (age, 23 +/- 0.5 wk). Incubation of aged mouse carotid arteries with the cell-permeable SOD mimetic Mn(III)tetra(4-benzoic acid)porphyrin chloride normalized relaxation to ACh and DEA-NONOate. Furthermore, production of superoxide anion in aorta and serum levels of amyloid P component, which is the murine analog of C-reactive protein, was increased in old mice. In aorta, neither the concentration of BH4 nor the ratio of reduced BH4 to the oxidation products were different between young and aged mice. Our results demonstrate that in mice, aging impairs relaxation mediated by NO most likely by increased formation of superoxide anion. Oxidation of BH4 does not appear to be an important mechanism underlying vasomotor dysfunction in aged mouse arteries.

Nitric oxide formation in the oropharyngeal tract: possible influence of cigarette smoking

Cigarette smoking reduces the level of nitric oxide (NO) in exhaled air by an unknown mechanism. The view that part of the effect of cigarette smoking on NO production should occur in the oropharyngeal tract is supported by several studies. We have therefore compared smokers and non-smokers regarding non-enzymatic formation of NO from nitrite in the oral cavity since this is a primary candidate target for cigarette smoke. We have also looked at NO synthase-dependent NO formation in the mucosa of the oropharyngeal tract as an alternative target for the inhibitory effect induced by cigarette smoke. Smokers exhaled 67% lower levels of NO than controls (p<0.01, n=15 each group). We could not detect any significant difference in salivary nitrite, nitrate or ascorbate between smokers and non-smokers. Mouthwash with the antibacterial agent chlorhexidine reduced salivary nitrite (-65%) and exhaled NO levels (-10%) similarly in the two groups. Immunohistochemical techniques revealed dense expression of inducible (but not endothelial or neuronal) NO synthase in the squamous epithelium of non-inflamed tonsillar and gingival tissue biopsies. In the same biopsies, significant Ca2+ -independent citrulline-forming activity was detected. We found no difference between smoking and non-smoking subjects regarding NO-synthase expression and in vitro activity. In another group of non-smoking subjects (n=10), spraying the oropharyngeal tract with the NO-synthase inhibitor NG-monomethyl-L-arginine (250 mg) significantly reduced exhaled NO levels for at least 30 min (-18%, p<0.01). Our data suggest that cigarette smoking does not affect non-enzymatic NO formation from nitrite in saliva. However, NO is also formed by inducible NO synthase in the squamous epithelium of the normal oropharyngeal tract. We suggest that cigarette smoking may down-regulate enzymatic NO formation in the oropharyngeal compartment as well as in the bronchial compartment.

Comparison of tetrahydrobiopterin and L-arginine on cerebral blood flow after controlled cortical impact injury in rats

The purpose of this study was to compare the effects of L-arginine and tetrahydrobiopterin administration on post-traumatic cerebral blood flow (CBF) and tissue levels of NO in injured brain tissue. Rats were anesthetized with isoflurane. Mean blood pressure, intracranial pressure, cerebral blood flow using laser Doppler flowmetry (LDF) and brain tissue nitric oxide (NO) concentrations were measured prior to, and for 2 h after a controlled cortical impact injury. L-arginine, 300 mg/kg, tetrahydrobiopterin, 10 mg/kg, or equal volume of saline was given at 5 min after injury. In the saline-treated animals, LDF decreased to 34 +/- 4% of baseline values after injury. NO concentration also decreased by approximately 20 pmol/ml from baseline values. L-arginine and tetrahydrobiopterin administration both resulted in a significant preservation of tissue NO concentrations and an improvement in LDF, compared to control animals given saline. These studies demonstrate that tetrahydrobiopterin administration has a beneficial effect on cerebral blood flow that is similar to L-arginine administration, and may suggest that depletion of tetrahydrobiopterin plays a role in the post-traumatic hypoperfusion of the brain.

The 5,10-methylenetetrahydrofolate reductase C677T polymorphism interacts with smoking to increase homocysteine

Elevated homocysteine is a risk marker for several human pathologies. Risk factors for elevated homocysteine include low folate and homozygosity for the T allele of the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism. Because nitric oxide may inhibit folate catabolism and endothelial nitric oxide synthase activity is reduced in smokers, we postulated that smoking status might modify the impact of the MTHFR C677T polymorphism on homocysteine (tHcy) concentrations. We tested this hypothesis in a healthy young adult population for which MTHFR C677T genotypes and tHcy concentrations were previously reported. The MTHFR 677TT genotype was significantly associated with elevated tHcy concentrations in smokers (P = 0.001) but not in non-smokers (P = 0.36). Among smokers, the MTHFR 677TT genotype was significantly associated with high tHcy in heavy smokers (P = 0.003) but not light smokers (P = 0.09), in men (P = 0.003) but not women (P = 0.11), and in subjects from the lowest serum folate quartile (P = 0.49) but not from folate quartiles 2-4 (P = 0.49). After adjustment for nutritional variables, interactions between MTHFR C677T genotype and NOS3 G894T genotype, and between MTHFR genotype, smoking status and gender were statistically significant. We propose that hyperhomocysteinemia in MTHFR 677TT homozygote smokers is the consequence of mild intracellular folate deficiency caused by a smoking-related reduction of NOS3 activity that is exacerbated when serum folate is low.

Oral snuff impairs endothelial function in healthy snuff users

AIMS

Oral snuff is a less dangerous drug and therefore a good substitute for cigarette smoking. The aim of this study was to determine whether oral moist snuff induces acute endothelial dysfunction. Previous studies have shown that endothelial dysfunction predicts cardiovascular morbidity.

METHODS AND RESULTS

Twenty healthy middle-aged snuff users underwent ultrasound assessment of endothelial-dependent flow-mediated dilatation (FMD) of the brachial artery. FMD measurements were performed in duplicate at baseline and then 20 and 35 min after the administration of 1 g portion-bag-packed moist snuff or placebo. Ten of the subjects were examined twice according to a randomized cross-over procedure, once with snuff and once with placebo. All images were arbitrarily analysed off-line by a single blinded observer. FMD values declined significantly from 3.4 +/- 2.0% to 2.3 +/- 1.3% (P < 0.05) 35 min after the administration of 1 g oral moist snuff. Heart rate, systolic and diastolic blood pressure increased significantly (P < 0.05) after snuff administration. All parameters remained unchanged after placebo.

CONCLUSIONS

Oral moist snuff significantly impaired FMD of the brachial artery. As endothelial dysfunction predicts cardiovascular morbidity, use of oral snuff should be discouraged.

F-actin capping (CapZ) and other contractile saphenous vein smooth muscle proteins are altered by hemodynamic stress: a proteonomic approach

Increased force generation and smooth muscle remodeling follow the implantation of saphenous vein as an arterial bypass graft. Previously, we characterized and mapped 129 proteins in human saphenous vein medial smooth muscle using two-dimensional (2-D) PAGE and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Here, we focus on actin filament remodeling in response to simulated arterial flow. Human saphenous vein was exposed to simulated venous or arterial flow for 90 min in vitro, and the contractile medial smooth muscle was dissected out and subjected to 2-D gel electrophoresis using a non-linear immobilized pH 3-10 gradient in the first dimension. Proteins were analyzed quantitatively using PDQuest 2-D software. The actin polymerization inhibitor cytochalasin B (1 microm) prevented increases in force generation after 90 min of simulated arterial flow. At this time point, there were several consistent changes in actin filament-associated protein expression (seven paired vein samples). The heat shock protein HSP27, identified as a three-spot charge train, showed a 1.6-fold increase in abundance (p = 0.01), but with reduced representation of the phosphorylated Ser(82) and Ser(15)Ser(82) isoforms (p = 0.018). The abundance of actin-capping protein alpha2 subunit CapZ had decreased 3-fold, p = 0.04. A 19-kDa proteolytic fragment of actin increased 2-fold, p = 0.04. For the four-spot charge train of gelsolin, there was reduced representation of the more acidic isoforms, p = 0.022. The abundance of other proteins associated with actin filaments, including cofilin and destrin, remained unchanged after arterial flow. Actin filament remodeling with differential expression and/or post-translational modification of proteins involved in capping the barbed end of actin filaments, HSP27 and CapZ, is an early response of contractile saphenous vein smooth muscle cells to hemodynamic stress. The observed changes would favor the generation of contractile stress fibers.