Cigarette smoking and endothelial injury: a review

Impact of Smoking Status in Free Deep Inferior Epigastric Artery Perforator Flap Breast Reconstruction: A Multicenter Study

BACKGROUND

 Several patient-related factors have been identified with regard to the safety and efficacy of breast reconstructions. Using the largest database available in Europe, the presented study investigated the impact of cigarette smoking on deep inferior epigastric artery perforator (DIEP) free-flap breast reconstructions.

METHODS

 In total, 3,926 female patients underwent 4,577 free DIEP-flap breast reconstructions after malignancies in 22 different German breast cancer centers. The cases were divided into two groups: nonsmokers (NS) and smokers (S). Impact of smoking on surgical complications, controlled for covariates, and cluster effects within the cancer centers were analyzed by using generalized linear mixed models.

RESULTS

 Overall, there was no significant difference between the groups of patients regarding the rate of total flap loss. However, the rate of partial flap loss (0.9 vs. 3.2%, p < 0.001) and wound-healing disturbances requiring revision surgery (donor site: 1.5 vs. 4.0; recipient site: 1.3 vs. 3.6%, both p < 0.001) was significantly higher in smokers. Multivariable analysis identified smoking to be an independent risk factor for revision surgery (p = 0.001) and partial flap loss (p < 0.0001).

CONCLUSION

 Our findings suggest that successful free tissue transfer can be achieved in smokers despite higher rates of partial flap losses and wound-healing disturbances. However, patients with a history of smoking requiring DIEP flap reconstruction should be critically evaluated preoperatively, informed in detail about the higher risk of complications and encouraged to quit smoking prior to surgery.

Large high-density lipoprotein particle number is independently associated with microvascular function in patients with well-controlled low-density lipoprotein concentration: A vasodilator stress magnetic resonance perfusion study

BACKGROUND

Abnormalities in total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglycerides are associated with microvascular dysfunction. Recent studies suggest that lipid subfractions better predict atherogenic burden than a routine lipid panel. We sought to determine, whether lipid subfractions are more strongly associated with microvascular function and subclinical atherosclerosis, than conventional lipid measurements using vasodilator stress cardiovascular magnetic resonance (CMR).

METHODS

Twenty-four adults referred for risk stratification from a lipid clinic with low-density lipoprotein cholesterol (LDL-C) <100 mg/dL underwent vasodilator CMR. Time-intensity curves generated from stress and rest perfusion images were used to determine the area under the curve (AUC) for the mid-ventricular slice myocardium and the left ventricular (LV) cavity. Myocardial perfusion reserve index (MPRi) was defined as stress to rest ratio of mid-ventricular myocardium AUC, normalized to LV cavity AUC. Lipid panels that included subfractions of LDL and high-density lipoprotein (HDL) were measured using nuclear magnetic resonance testing. The association between MPRi and lipid parameters was examined using univariate linear regression; lipid components statistically correlated with MPRi (P < .05) were then subjected to multivariate analysis.

RESULTS

Univariate regression analysis showed MPRi was associated with HDL-C, triglycerides, large HDL-P, and small LDL-P; no association was found between MPRi and total cholesterol, LDL-C, total LDL-P, or total HDL-P. Using multivariate analysis, large HDL-P was independently associated with MPRi.

CONCLUSIONS

In patients with LDL-C <100 mg/dL, large HDL-P is independently associated with CMR-derived myocardial perfusion reserve, a surrogate for microvascular function and subclinical atherosclerosis. Further studies using lipid subfractions to better understand cardiovascular risks are warranted.

Endothelium and its alterations in cardiovascular diseases: life style intervention

The endothelium, which forms the inner cellular lining of blood vessels and lymphatics, is a highly metabolically active organ that is involved in many physiopathological processes, including the control of vasomotor tone, barrier function, leukocyte adhesion, and trafficking and inflammation. In this review, we summarized and described the following: (i) endothelial cell function in physiological conditions and (ii) endothelial cell activation and dysfunction in the main cardiovascular diseases (such as atherosclerosis, and hypertension) and to diabetes, cigarette smoking, and aging physiological process. Finally, we presented the currently available evidence that supports the beneficial effects of physical activity and various dietary compounds on endothelial functions.

[Risk factor "smoking" : smoking cessation in patients with cardiovascular diseases]

Smoking is the most frequent cause of avoidable premature death. Annually, almost 6 million people die due to nicotine consumption. Comparing modifiable cardiovascular risk factors, smoking has the strongest impact on cardiovascular mortality. More than 50% of all premature myocardial infarctions are related to nicotine consumption. Even in patients with known coronary disease receiving optimal medical therapy, there is a remarkable additional preventive effect of smoking cessation detectable. Therefore, smoking cessation is an essential component of primary and secondary prevention strategies. Smoking cessation programs applying a combination of behavior therapy and supporting medical treatment have been demonstrated to be the most effective.

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.

Nicotine enlivenment of blood flow recovery following endothelial progenitor cell transplantation into ischemic hindlimb

Nicotine has been demonstrated to stimulate postnatal angiogenesis, having an antiapoptotic effect on endothelial cells. Given the extent of this angiogenesis-promoting effect, we hypothesized that nicotine may also stimulate postnatal vasculogenesis on endothelial progenitor cells (EPCs). Our analyses reveal some intriguing results using an in vitro assay with 2 x 10(-6) M of nicotine (smoker's average nicotine concentration and the dose of nicotine replacement therapy). The proliferation and migration activities of human EPCs cultured from peripheral blood mononuclear cells of non-smoking healthy volunteers were not affected by nicotine. The effect of nicotine on EPC survival was significantly enhanced under serum starvation on the ratio of Hoechest 33342-stained pyknotic nuclear cells as well as Annexin-V-stained cells to total cells. Furthermore, the antiapoptotic effect of nicotine was blocked completely by nicotinic acetylcholine receptor (nAChR) antagonist hexamethonium. Next, we verified how nicotine acts in vivo. Nicotine (100 ng/ml) was administered orally for 7 days before and 4 weeks after injection of cultured EPCs (1 x 10(5) /mouse) into the tail veins of 8-week-old athymic nude mice with ischemic hindlimbs. Laser doppler imaging analysis indicated that blood perfusion in the ischemic hindlimb was significantly enhanced in EPCs plus nicotine, as compared with EPCs alone. These findings suggest nicotine improves blood flow following EPC transplantation in patients with ischemic diseases.

Tobacco control for anesthesiologists

Anesthesiologists daily witness the consequences of tobacco use, the most common preventable cause of death. Smoking-related diseases such as atherosclerosis and chronic obstructive pulmonary disease increase anesthetic risk, and even smokers without overt disease are at increased risk for morbidity such as pulmonary and wound-related complications. Evidence suggests that stopping smoking will reduce the frequency of these complications. Nicotine and the other constituents of cigarette smoke, such as carbon monoxide, have important physiologic effects that may affect perioperative management. In addition, it is now apparent that the scheduling of elective surgery represents an excellent opportunity for smokers to quit in the long term. This review serves as an introduction to tobacco control for anesthesiologists, first examining issues of importance to perioperative management. It then discusses how anesthesiologists and other perioperative physicians can help address tobacco use, both at an individual level with their patients, and by contributing to the implementation of effective public health strategies in their countries. Anesthesiologists can play a key role in helping their patients quit smoking. Effective tobacco control measures applied to surgical patients will not only improve immediate perioperative outcomes but also long-term health.

Light cigarette smoking impairs coronary microvascular functions as severely as smoking regular cigarettes

BACKGROUND

Smoking is the most prevalent and most preventable risk factor for cardiovascular diseases. Smoking low-tar, low-nicotine cigarettes (light cigarettes) would be expected to be less hazardous than smoking regular cigarettes owing to the lower nicotine and tar yield.

OBJECTIVE

To compare the chronic and acute effects of light cigarette and regular cigarette smoking on coronary flow velocity reserve (CFVR).

METHODS

20 regular cigarette smokers (mean (SD) age 24.8 (5.0)), 20 light cigarette smokers (mean age 25.6 (6.4)), and 22 non-smoker healthy volunteers (mean age 25.1 (4.2)) were included. First, each subject underwent echocardiographic examination, including CFVR measurement, after a 12 hour fasting and smokeless period. Two days later, each subject smoked two of their normal cigarettes in a closed room within 15 minutes. Finally, within 20-30 minutes, each subject underwent an echocardiographic examination, including CFVR measurement.

RESULTS

Mean (SD) CFVR values were similar in light cigarette and regular cigarette smokers and significantly lower than in the controls (2.68 (0.50), 2.65 (0.61), 3.11 (0.53), p = 0.013). Before and after smoking a paired t test showed that smoking two light cigarettes acutely decreased the CFVR from 2.68 (0.50) to 2.05 (0.43) (p = 0.001), and smoking of two regular cigarettes acutely decreased CFVR from 2.65 (0.61) to 2.18 (0.48) (p = 0.001).

CONCLUSION

Smoking low-tar, low-nicotine cigarettes impairs the CFVR as severely as smoking regular cigarettes. CFVR values are similar in light cigarette and regular cigarette smokers and significantly lower than in controls.

Direct effects of nicotine on contractility of the uterine artery in pregnancy

Recent studies indicate that smoking/nicotine increases maternal blood pressure and decrease in uterine blood flow in pregnancy. However, the mechanisms are not fully understood. The present study was designed to test the hypothesis that nicotine exposure decreases endothelium-dependent relaxation and increases vascular contractility of the uterine artery in pregnancy. Uterine arteries were isolated from near-term ( approximately 140 days gestation) pregnant ewes. Arteries were subjected to acute (20 min) or chronic (48 h) nicotine treatment, and agonist-induced contractions and relaxations were measured in tissue bath. Endothelial eNOS was detected by immunohistochemistry in situ in arteries and by Western blotting in isolated endothelial cells. Chronic nicotine treatment produced a concentration-dependent increase in alpha(1)-adrenoceptor agonist phenylephrine-induced contractions. In contrast, the acute treatment showed no effect. Inhibition of eNOS with N(G)-nitro-L-arginine (L-NNA) significantly increased phenylephrine-induced contractions, which was abolished in uterine arteries after chronic nicotine treatment. In the presence of L-NNA, there was no significant difference in phenylephrine-induced contractions between control and nicotine-treated vessels. Chronic, but not acute, nicotine treatment significantly attenuated the calcium ionophore A23187-induced relaxations. Unlike A23187, the endothelium-independent relaxation mediated by sodium nitroprusside was not affected by nicotine. Endothelial eNOS protein levels and the phosphorylation levels of eNOS(Ser1179) were significantly decreased in nicotine-treated uterine arteries. The results suggest that nicotine impairs uterine vascular function in pregnancy, which may lead to an increased vascular resistance and a decrease in uterine blood flow.

Cigarette smoking increases the risk of root canal treatment

Few studies have investigated smoking as a risk factor for root canal treatment. We studied the effect of smoking on the incidence of root canal treatment, controlling for recognized risk factors, in 811 dentate male participants in the VA Dental Longitudinal Study. Participants were not VA patients. Follow-up ranged from 2 to 28 years. Root canal treatment was verified on radiographs and evaluated with proportional hazards regression models. Compared with never-smokers, current cigarette smokers were 1.7 times as likely to have root canal treatment (p < 0.001), but cigar and/or pipe use was not significantly associated with root canal treatment. The risk among cigarette smokers increased with more years of exposure and decreased with length of abstinence. These findings suggest that there is a dose-response relationship between cigarette smoking and the risk of root canal treatment.

Cardiovascular Sequelae of Tobacco Smoking

Smoking is a known risk factor for cardiovascular disease and has been implicated in sudden cardiac death. Hypertension, hypercholesterolemia, physical inactivity, and smoking are the leading contributors to poor cardiovascular health. This article reviews the cardiovascular pathology inherent with smoking and provide insight to help develop an appropriate plan of care.

Acrolein produces nitric oxide through the elevation of intracellular calcium levels to induce apoptosis in human umbilical vein endothelial cells: Implications for smoke angiopathy

Acrolein is a highly electrophilic alpha, beta-unsaturated aldehyde, the levels of which are increased in the blood of smokers. To determine if acrolein is involved in the pathology of smoke angiopathy, the effect of acrolein on human umbilical vein endothelial cells (HUVEC) was examined. Intracellular nitric oxide (NO) levels, determined using diaminofluorescein-2 diacetate (DAF-2 DA), an NO sensitive fluorescent dye, were found to be increased after treatment in HUVEC with 10 microM acrolein. The measurement of nitrite with 2,3-diaminonaphthalene and a Western blot analysis revealed that nitrite and S-nitroso-cysteine levels were increased in a dose-dependent manner, confirming that NO production is increased by acrolein. The increase was not reduced by treatment with 10mM N-acetyl-l-cysteine (NAC), an anti-oxidant, but was reduced with 10 microM of the intracellular calcium chelator, 1,2-bis (o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester. Acrolein-stimulated NO production was significantly reduced by pretreatment with 1mM N(G)-nitro-l-arginine-methyl ester (L-NAME), an NO synthase inhibitor. The cytotoxicity of acrolein was reduced by pretreatment with 10 microM 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO), an intracellular NO scavenger, or 1mM L-NAME, whereas it was not reduced by 10mM NAC, 20 microM Curcumin, another peroxide scavenger, or 100 microM Mn(III)TMPyP, a superoxide dismutase mimic. Nuclear staining and a Western blot analysis using an anti-cleaved caspase 3 antibody revealed that the reduced viability of HUVEC by acrolein was due to apoptosis, which was reversed after pretreatment with 0.1mM carboxy-PTIO or 1mM L-NAME. Thus, acrolein increases intracellular calcium production to induce intracellular NO production by a calcium-dependent NO synthase, possibly eNOS, and the excess and rapid increase in NO might lead to the apoptosis of HUVEC. These data suggest that acrolein might be involved in the pathology of smoke angiopathy through the NO-induced apoptosis of endothelial cells.

[Prevention of coronary heart disease: smoking]

Smoking is the leading preventable cause of illness and premature death in Germany, claiming over 110,000 lives a year because it directly increases the risk of dying from heart disease, stroke, emphysema and a variety of cancers. The overwhelming majority of smokers begin tobacco use before they reach adulthood. Among those young people who smoke, the average age is now 13-14. In Germany, about 39% of male and 31% of female adults (age 18-60 years) continue to smoke, despite information about the unequivocally negative health consequences of smoking. The exact mechanisms of smoking-related vascular disease are not yet known. Smoking causes acute hemodynamic alterations such as increase in heart rate, systematic and coronary vascular resistance, myocardial contractility, and myocardial oxygen demand. These short-term effects could lower the ischemic threshold in smokers with coronary artery disease and contribute to the increased risk for acute cardiovascular events. Endothelial damage is thought to be an initiating event in atherosclerosis and early studies have demonstrated that long-term smoking has direct toxic effects with structural changes of human endothelial cells. Recent research has shown the importance of the functional role of the endothelium in regulating vascular tone, platelet-endothelial interactions, leukocyte adhesion and smooth muscle cell proliferation via synthesis and release of a variety of substances such as nitric oxide. There is strong evidence that smoking leads to endothelial dysfunction mainly by increased inactivation of nitric oxide by oxygen-derived free radicals. Smoking also increases oxidative modification of LDL and is associated with lower HDL plasma levels. Smoking induces a systemic inflammatory response with increased leukocyte count and elevation of the C-reactive protein level. Importantly, the prothrombotic effects of smoking have been repeatedly demonstrated to cause alterations in platelet function, imbalance of antithrombotic vs prothrombotic factors, and decrease of fibrinolytic activity. Given the enormous health hazard of tobacco use, complete abstinence from smoking should be achieved. Smoking cessation counselling should be given to healthy subjects and even more vigorously to patients with manifested disease. Every effort should be undertaken to prevent children and adolescents from starting to smoke. Brief tobacco dependence treatment is effective, and every smoker should be offered at least brief treatment at every office visit. More intensive treatment is more effective in producing long-term abstinence from tobacco. Nicotine replacement therapy (nicotine patches or gum), clinician-delivered social support, and skills training are the three most effective components of smoking cessation treatment. A framework for tobacco control measures is necessary to reduce tobacco consumption and exposure to tobacco smoke. Recommendations on specific tobacco control interventions are: 1. increase in tobacco taxes; 2. comprehensive tobacco advertising bans; 3. legislation prohibiting smoking in work and public places; 4. prohibiting the sales of tobacco products to persons under 18; 5. comprehensive disclosure of the physical, chemical and design characteristics of all tobacco products; 6. training of health professionals to promote smoking prevention and cessation interventions; and 7. development of a national network of smoking cessation treatment services.

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.

Protein C pathway impairment in nonsymptomatic cigarette smokers

Increased risk of thrombosis in cigarette smokers implies the existence of an underlying prethrombotic state. It is known that oxidative damage to the endothelium surface occurs in chronic smokers. Protein C activation takes place mostly on the endothelium of small vessels and the anticoagulant activity of protein C requires the presence of lipid membranes that are vulnerable to oxidation. Our objective was to analyze the relationship between smoking and plasma levels of activated protein C, protein C zymogen, activated protein C complexed with serpins, total and free protein S, C4b-binding protein, and thrombomodulin, as well as fibrinogen, fibrinopeptide A, and protease-cleaved antithrombin III. Of the 189 plasma donors used in this study 83 were nonsymptomatic smokers (age range 20-44 years, women/men ratio = 1.13) and 106 were healthy nonsmokers (age range 22-59 years, women/men ratio = 1.36). Smokers had 23.3% lower circulating activated protein C than nonsmokers (p = 0.003) and the differences were more pronounced in males than in females. Protein C levels were also significantly lower in smokers than in nonsmokers (p = 0.034). Correlations were negative between the intensity of smoking and circulating activated protein C levels (r = -0.31, p = 0.004) and between smoking and the ratio of activated protein C to protein C zymogen (r = -0.37, p = 0.001). Positive correlations were found between smoking intensity and fibrinogen (r = 0.21, p = 0.042), or fibrinopeptide A (r = 0.219, p = 0.034). Other parameters tested did not show a statistically significant dose-response for the number of cigarettes smoked. Cigarette smoke dose-dependent hypercoagulability due to acquired activated protein C deficiency could contribute to the increased risk of thrombosis in smokers.

The GPIIIa (beta3 integrin) PlA polymorphism in the early development of coronary atherosclerosis

The GPIIIa (beta3 integrin) is an integral part of two glycoprotein receptors - the GP(IIb/IIIa) fibrinogen receptors in platelets and the GP(V/IIIa) vitronectin receptors in endothelium and vascular smooth muscle cells (vSMC). The PlA polymorphism of the gene for GPIIIa (beta3 integrin) has been suggested to play an important role in the progression of coronary artery disease (CAD) and in coronary thrombosis. Whether the action of the PlA polymorphism is due to differences in platelet aggregability or function of the vSMC and endothelial GPIIIa is not known. The association of the PlA polymorphism with the early, non-complicated atherosclerosis and CAD was studied in the Helsinki Sudden Death Study (HSDS) comprising two independent, autopsy series of altogether 700 middle-aged Caucasian Finnish men (33-70 year) suffering sudden out-of-hospital death. The burden of complicated lesions was greater in men with the A2 allele (heterozygotes or homozygotes for A2) (P=0.01) compared with PlA1/A1 homozygotes in the entire series. To further estimate the role of platelet-independent GPIIIa receptors, we excluded all cases with coronary thrombosis and thrombus-overlaid complicated lesions. In this subset of men, fibrous coronary lesions were more frequent (OR 2.9; P<0.01) in the coronary arteries of PlA1/A1 homozygotes compared with men with the PlA2 allele. Moreover, men with the PlA1/A1 genotype also had more stenotic coronary arteries (P<0.05) compared with men with the A2 allele at this early, non-complicated stage of atherosclerosis. The findings of this study suggest that Pl(A1/A1) homozygotes may be prone to early atherosclerosis and more rapid progression of stable CAD whereas carriers of the PlA2 allele are more prone to thrombotic complications. We hypothesize that the PlA polymorphism may account for the early atherosclerosis by affecting the function of endothelial and vSMC GP(V/IIIa) receptors, whereas the PlA polymorphism on platelet GP(IIb/IIIa) receptors may play a major role in coronary thrombosis.

Gender difference in the influence of smoking on arterial wall thickness

BACKGROUND

We hypothesized that arterial wall thickening, an early atherogenic alteration, might be associated with smoking differently according to gender, considering the cardiovascular protection of female sex hormones.

METHODS AND RESULTS

We measured ultrasonographically carotid and femoral intima-media thickness (IMT) in 194 men and 330 women without risk factors other than smoking. In men: (i) current smokers had greater carotid and femoral IMT (P<0.01, P<0.001) and former smokers had greater femoral IMT (P<0.01) than never smokers; (ii) in pooled never, current and former smokers carotid and femoral IMT correlated to current daily smoking (P<0.01) and lifelong smoking (P<0.001); and (iii) carotid and femoral IMT correlated to age in never smokers (P<0.001), current smokers (P<0.01, P<0.001) and former smokers (P<0.01), with greater slopes in current than in former smokers at carotid site (P<0.05) and in current than in never smokers at femoral site (P<0.05). In women: (i) IMT did not differ by smoking status; (ii) in pooled smokers and non smokers femoral IMT correlated to current daily smoking (P=0.01) and to lifelong smoking (P<0.01) with a lower slope than in men (P<0.001), while carotid IMT did not; and (iii) carotid and femoral IMT correlated to age in never smokers (P<0.001), current smokers (P<0.001, P<0.05) and former smokers (P<0.001, P<0.01) with no different slopes.

CONCLUSION

Smoking-related increase in IMT existed in men but not in women, suggesting a possible protection of female gender from early structural arterial alteration of smoking.

Cigarette smoking, endothelial injury and cardiovascular disease

Despite the fact that the epidemiological evidence linking cigarette smoking with cardiovascular disease is overwhelming, the precise components of cigarette smoke responsible for this relationship and the mechanisms by which they exert their effect have not yet been elucidated. There are however, some promising pointers as a result of recent developments and this review concentrates on new evidence since earlier reviews of this topic. It is now known that the endothelium has a vastly more important role than was ever thought to be the case a decade ago. Its role in health and disease is increasingly understood, as is the relationship between endothelial injury and the development of atherosclerosis. There is considerable evidence that cigarette smoking can result in both morphological and biochemical disturbances to the endothelium both in vivo and in cell culture systems. Cigarette smoke is a complex mixture and only a few components have been extensively studied. Nicotine and carbon monoxide are much less damaging than is whole smoke. However the free radical components of cigarette smoke have been shown to cause damage in model systems. Further work will be necessary to consolidate the evidence base but the data reported in this review suggest that the free radical components of cigarette smoke may be responsible for the morphological and functional damage to endothelium that has been observed in model systems.

The GPIIIa Pl(A) polymorphism in the progression of abdominal aortic atherosclerosis

Glycoprotein IIIa is expressed in platelets as part of the fibrinogen receptor and also in vascular endothelium where it mediates smooth muscle cell proliferation. The association between the glycoprotein GPIIIa Pl(A) polymorphism and the stage of atherosclerosis in the abdominal aorta was studied in a prospective autopsy study series of 300 middle-aged men (33-69 years). The Pl(A) genotype was determined by RFLP-PCR. The stage of atherosclerosis in the abdominal aorta was determined by computer-assisted morphometry. Elevated, fibrous lesions were more frequently (P=0.05) found in the abdominal aortas of men with the Pl(A1) homozygous genotype compared to men with the A2 allele (OR 2.3; 95% CI 0.99-5.2). The area of complicated lesions was significantly greater in men with Pl(A2)-positive genotypes compared to A1 homozygotes. The association with complicated lesions was especially strong in men over 60 (P=0.002). These results suggest that Pl(A) polymorphism is involved in the progression of atherosclerosis in the abdominal aorta. The association of men possessing the Pl(A2) allele with slower development of fibrous lesions and with greater area of complicated lesions in the abdominal aorta may result from genotypic differences in the smooth muscle cell proliferation after slight injuries to the endothelium mediated by glycoprotein IIIa or from genotypic differences in platelet fibrinogen binding or both.

Glycoprotein IIIa Pl(A) polymorphism associates with progression of coronary artery disease and with myocardial infarction in an autopsy series of middle-aged men who died suddenly

Glycoprotein IIIa (GPIIIa) has a key role in the aggregation of thrombocytes, and it also mediates intimal hyperplasia after endothelial injuries; the possible association of the Pl(A1/A2) polymorphism of the gene for GPIIIa with coronary thrombosis and with the progression of coronary artery disease (CAD) is still to be confirmed. Therefore, the association of the Pl(A) polymorphism with the development of coronary atherosclerosis, coronary narrowing, and myocardial infarction (MI) was studied in a prospective, consecutive autopsy series of 300 middle-aged, white Finnish men (33 to 69 years) suffering sudden out-of-hospital or violent death. Coronary atherosclerosis was measured morphometrically and the coronary stenosis percentage determined from a cast rubber model of the coronary tree. We found a significant inverse relation (P=0.01) between the Pl(A2)-positive genotype and coronary artery stenosis. The frequency of possessing the Pl(A2) allele was significantly (odds ratio [OR] 0.45, 95% confidence interval [CI] 0.22 to 0.98) lower among men with >50% coronary stenosis (18.3%) than among those with <25% stenosis (32.9%). Although the Pl(A) polymorphism was not directly associated with MI, the Pl(A2) allele was present in 11 of the 22 men (50%) with MI and coronary thrombosis (OR 6.6, 95% CI 2.1 to 22.8) but in only 6 of the 47 (12.8%) with MI associated with severe stenosis in the absence of thrombosis. In line with this result, men possessing the Pl(A2) allele also had a larger area of fissured and ulcerated complicated lesions in their coronary arteries (P<0.05). The present results suggest that the Pl(A) polymorphism is involved in the development of CAD and MI. Men with the Pl(A2) allele may harbor more thin-walled, vulnerable coronary plaques, plaques prone to rupture, leading to massive, fatal thrombosis. In contrast, men homozygous for the Pl(A1) allele may more often show stable plaques and present with infarction caused by progressive coronary stenosis.

Smokeless tobacco use and atherosclerosis: an ultrasonographic investigation of carotid intima media thickness in healthy middle-aged men

There is well-documented evidence of accelerated atherosclerosis in smokers but the mechanisms still remain unclear. The relationship to the use of smokeless tobacco, involving high exposure to nicotine, have not been evaluated before. The possible role of nicotine was investigated in a clinical study of the intima media thickness in the carotid artery of 143 healthy, middle-aged men (35-60 years old) with different tobacco consumption habits. B-mode ultrasonography was performed and biochemical risk factors for cardiovascular disease (serum lipids, serum lipoproteins and plasma fibrinogen) were determined. Long term smokeless tobacco users (n = 28) did not differ significantly from never-users (n = 40) regarding bulb intima media thickness (0.80 +/- 0.13 versus 0.78 +/- 0.12 mm) or common carotid intima media thickness (0.67 +/- 0.11 versus 0.68 +/- 0.11 mm), whereas smokers (n = 29) had significantly increased wall measurements (bulb 0.87 +/- 0.19, P = 0.002 common carotid 0.74 +/- 0.13, P = 0.03) compared to never-users. Only in smokers were biochemical risk factors significantly altered towards an elevated risk. Significant effects of interaction of smoking and increased s-cholesterol levels on carotid intima media thickness were also found. Smokeless tobacco users showed similar tendencies, but without definite statistical significance. On the basis of these data, it appears most likely that the increased occurrence of atherosclerosis in smokers is caused by other components of tobacco smoke than nicotine.

Induction of endothelial cell injury by cigarette smoke

Cigarette smoke contains different populations of free radicals which may be responsible for endothelial cell (EC) injury of smokers. The purpose of this study was to examine the effects of gas-phase cigarette smoke on EC endothelium-derived relaxing factor (EDRF)/NO-guanylate cyclase (GC)-cGMP pathway and on EC detachment-type injury after incubation with smoke. Furthermore, we examined whether different kind of antioxidants can prevent smoke-caused EC injury. We measured cGMP pathway using direct (sodium nitroprusside, SNP) and indirect (A23187, the calcium ionophore and bradykinin, BK) activators of GC. Directly and indirectly stimulated EC cGMP production dose-dependently decreased and EC detachment increased after incubation with smoke. Externally added thiols (glutathione, GSH; D-Penicillamine, DP; N-acetylcysteine, NAC) protected EC from damage of cGMP production and cell detachment. Other antioxidants (catalase, deferoxamine and superoxide dismutase) were ineffective. These results suggest that the thiol containing GC in EC is destroyed or inactivated or thiol like species responsible for activation of GC is incomplete in EC after incubation with smoke. It is also possible that externally added thiols bind an unknown component of smoke and this way, EC is protected. EC injury may contribute to vascular diseases associated with cigarette smoking.

Microcirculatory vasoconstrictor response: relationship with vital capacity and smoking

Vasoconstrictor response (VR) induced by inspiratory gasp exhibited a strong positive correlation with vital capacity (VC) which reflects the magnitude of the input stimulus for VR (Lau et al., Clin. Sci. 89:233-237, 1995). Whether a stoichiometric relationship existed between VC and VR is not known. We examined this question in two studies by determining VC and microcirculatory blood flow with laser Doppler flowmetry in healthy subjects. We first studied 40 non-smokers of different gender and age and found that the variation in VR cannot be eliminated by normalization with VC. In the second study we examined 10 young male smokers as well as matched non-smokers of identical VC, we found that smokers had reduced VR. Taking together, the present studies demonstrated that vasoconstrictor response (VR) was not determined by vital capacity alone and that smoking adversely affected VR in the absence of altered VC.

Age-related changes affecting atherosclerotic risk. Potential for pharmacological intervention

The incidence of cardiovascular diseases that are related to the atherosclerotic process increases exponentially with age. Organ lesions, the clinical manifestation of atherosclerotic disease, are late events due to complications in the plaque (ulceration, thrombosis, calcification) which are the result of an increased vulnerability to disruption of a previously stable plaque. The higher incidence of age-related clinical events could be explained by a rising sensitivity of plaques to destabilising factors, both parietal and humoral. The increased probability that a plaque in an elderly patient will became vulnerable could be related to those destabilising factors that significantly increase with aging, such as advanced glycation end-products. For these reasons, it seems most important that the analysis of these age-related destabilising factors, rather than those factors that promote the development of early atherosclerotic plaques, should be undertaken. Taking the point of view of a pharmacological intervention, this should eventually lead to a more complete understanding of this process.

Smokeless tobacco use and increased cardiovascular mortality among Swedish construction workers

OBJECTIVES

Little is known about the risks of cardiovascular disease associated with the use of smokeless tobacco, which produces blood nicotine levels similar to those caused by cigarette smoking.

METHODS

Male Swedish construction industry employees (n = 135,036) who attended a health examination were followed by studying cause-specific mortality during a 12-year period. The study population comprised 6297 smokeless tobacco users, 14,983 smokers of fewer than 15 cigarettes per day, 13,518 smokers of 15 or more cigarettes per day, 17,437 ex-smokers, 50,255 "other" tobacco users, and 32,546 nonusers.

RESULTS

The age-adjusted relative risk of dying from cardiovascular disease was 1.4 for smokeless tobacco users and 1.9 for smokers of 15 or more cigarettes per day, compared with nonusers. Among men aged 35 through 54 years at the start of follow-up, the relative risk was 2.1 for smokeless tobacco users and 3.2 for smokers. When data were adjusted for body mass index, blood pressure, and history of heart symptoms, the results were essentially unchanged. Cancer mortality was not raised in smokeless tobacco users.

CONCLUSIONS

Both smokeless tobacco users and smokers face a higher risk of dying from cardiovascular disease than nonusers. Although the risk is lower for smokeless tobacco users than for smokers, the excess risk gives cause for preventive actions.