Smoking depresses adipose lipoprotein lipase response to oral glucose

Cardiac function, myocardial fat deposition, and lipid profile in young smokers: a cross-sectional study

Background

There is a possibility that cardiac morphometric characteristics are associated with the lipid profile, that is, the composition and concentration of triglycerides, total cholesterol, HDL, LDL, and others lipoproteins in young smokers without comorbidities. Thus, this study aimed to evaluate the association of cardiac morphometric characteristics, myocardial fat deposition, and smoking cessation with the lipid profile of young smokers.

Methods

A clinical and laboratory evaluation of lipids and the smoking status was performed on 57 individuals, including both a smoker group and a control group. Cardiac magnetic resonance imaging (MRI) with proton spectroscopy was performed to identify cardiac changes and triglyceride (TG) deposition in myocardial tissue.

Results

No differences were observed between the groups (control vs. smokers) in relation to the amount of myocardial TG deposition (p = 0.47); however, when TG deposition was correlated with cardiac MRI variables, a positive correlation was identified between smoking history and myocardial TG deposition [hazard ratio (95% CI), 0.07 (0.03-0.12); p = 0.002]. Furthermore, it was observed that the smoking group had lower high-density lipoprotein cholesterol [51 (45.5-59.5) mg/dl vs. 43 (36-49.5) mg/dl, p = 0.003] and higher TG [73 (58-110) mg/dl vs. 122 (73.5-133) mg/dl, p = 0.01] and very-low-density lipoprotein cholesterol [14.6 (11.6-22.2) mg/dl vs. 24.4 (14.7-26.6) mg/dl, p = 0.01] values. In the control and smoking groups, a negative correlation between TGs and the diameter of the aortic root lumen and positive correlation with the thickness of the interventricular septum and end-diastolic volume (EDV) of both the right ventricle (RV) and left ventricle (LV) were noted. Moreover, in the RV, positive correlations with the end-systolic volume (ESV) index (ESVI), stroke volume (SV), ESV, and EDV were observed. Regarding serum free fatty acids, we found a negative correlation between their values and the diameter of the lumen of the ascending aortic vessel. Lipoprotein lipase showed a positive correlation with the SV index of the RV and negative correlation with the diameter of the lumen of the ascending aortic vessel.

Conclusion

Several associations were observed regarding cardiac morphometric characteristics, myocardial fat deposition, and smoking cessation with the lipid profile of young smokers.

The Effects of Smoking on the Diagnostic Characteristics of Metabolic Syndrome: A Review

Metabolic syndrome is a growing epidemic that increases the risk for cardiovascular disease, diabetes, stroke, and mortality. It is diagnosed by the presence of three or more of the following risk factors: 1) obesity, with an emphasis on central adiposity, 2) high blood pressure, 3) hyperglycemia, 4) dyslipidemia, with regard to reduced high-density lipoprotein concentrations, and 5) dyslipidemia, with regard to elevated triglycerides. Smoking is one lifestyle factor that can increase the risk for metabolic syndrome as it has been shown to exert negative effects on abdominal obesity, blood pressure, blood glucose concentrations, and blood lipid profiles. Smoking may also negatively affect other factors that influence glucose and lipid metabolism including lipoprotein lipase, adiponectin, peroxisome proliferator-activated receptors, and tumor necrosis factor-alpha. Some of these smoking-related outcomes may be reversed with smoking cessation, thus reducing the risk for metabolic disease; however, metabolic syndrome risk may initially increase post cessation, possibly due to weight gain. Therefore, these findings warrant the need for more research on the development and efficacy of smoking prevention and cessation programs.

Four-way decomposition of effect of cigarette smoking and body mass index on serum lipid profiles

Objective

Smoking and obesity are established risk factors of dyslipidemia, however, the interplay between them has not been well studied. This study aims to explore the joint effect of smoking and body mass index (BMI) on serum lipid profiles.

Methods

The study consisted of 9846 Chinese adults (mean age = 49.9 years, 47.6% males, 31.2% ever smokers), based on the China Health and Nutrition Survey. Serum lipid profiles included total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), apolipoprotein A (APO-A), and apolipoprotein B (Apo-B). The joint effect of smoking and BMI on serum lipids were examined by the four-way decomposition analysis and multivariate linear regression models.

Results

The four-way decomposition showed that the interplay between smoking and BMI was complicated. There was only indirect effect (the mediated effect) between smoking and BMI on TC, LDL-C and APO-B. The pure indirect effect was -0.023 for TC, -0.018 for LDL-C, and -0.009 for APO-B. For TG, HDL-C and APO-A, the interaction effect was dominant. The reference interaction (the interactive effect when the mediator is left to what it would be in the absence of exposure) was 0.474 (P < 0.001) for TG, -0.245 (P = 0.002) for HDL-C, and -0.222 (P < 0.001) for APO-A, respectively. The effect of BMI on TG, HDL-C and APO-A were significantly higher in smokers than in nonsmokers (TG: 0.151 in smokers versus 0.097 in nonsmokers, HDL-C: -0.037 versus -0.027, APO-A: -0.019 versus -0.009, P for difference < 0.001 for all).

Conclusion

These findings illustrate the joint effects of smoking and BMI on serum lipid profiles. There were significant interaction effects of smoking and BMI on TG, HDL-C and APO-A, while BMI maybe a mediator for the association of smoking with TC, LDL-C and APO-B. The effects between them were rather complex. Smoking cessation is necessary, especially for those overweight.

Relationships between Smoking Status, Cardiovascular Risk Factors, and Lipoproteins in a Large Japanese Population

Aims: Smoking is a major risk factor for cardiovascular disease (CVD), a leading cause of death and disability. Other CVD risk factors include age, gender, hypertension, diabetes, increased low-density lipoprotein cholesterol (LDL-C) and decreased high-density lipoprotein cholesterol (HDL-C). Our goal was to assess relationships between smoking status and CVD risk factors, with a focus on direct LDL-C, HDL-C, triglycerides (TG) and small dense LDL-C (sdLDL-C).

Methods: A total of 34,497 Japanese men and women, mean age 51 years, had their CVD risk factors including fasting serum total cholesterol, TG, HDL-C, sdLDL-C, and direct LDL-C assessed. One-way ANOVA and multiple linear regression analyses were carried to assess the interrelationships of these parameters with smoking.

Results: In both men and women, current smokers had significantly ( p ＜0.001) higher median TG (+19.6%, +16.9%) and sdLDL-C levels (+12.7%, +4.2%) levels, and significantly ( p ＜0.001) lower HDL-C levels (-7.3%, -4.3%) than non-smokers. They were also significantly ( p ＜0.05) more likely to have TG values ＞150 mg/dL (+56.8%, +116.3%), sdLDL-C ＞40.1 mg/dL (+28.8%, +44.9%), and HDL-C ＜40 mg/dL (+89.8%, +114.3%). Ex-smokers generally had lipid values that were intermediate between non-smokers and current smokers. Multivariate analysis confirmed the significance of these relationships.

Conclusion: Our data indicate that current cigarette smoking is associated with increased TG and sdLDL-C levels, as well as decreased HDL-C levels. Furthermore, smoking effect on lipid profiles remain after cessation. These data provide further justification for smoking cessation.

The Effect of Smoking on the Association between Long-Term Alcohol Consumption and Dyslipidemia in a Middle-Aged and Older Population

AIMS

The joint effects of chronic alcohol consumption and smoking on dyslipidemia remain unclear in a prospective design. This study examined the effect of smoking on the association between long-term alcohol consumption and risk of incident dyslipidemia.

METHODS

A total of 4467 participants (1866 men and 2601women) aged 40-69 years without dyslipidemia were recruited at baseline. Alcohol consumption was assessed biennially using a questionnaire and classified as light, moderate or heavy drinker. Smoking status was examined at baseline and categorized into non-smokers and current smokers. Dyslipidemia was defined as the presence of one or more of following: hypertriglyceridemia (triglyceride ≥200 mg/dL), hypercholesterolemia (total cholesterol ≥240 mg/dL), low high-density lipoprotein-cholesterol (HDL-C) < 40 mg/dL, or high low-density lipoprotein cholesterol ≥160 mg/dL.

RESULTS

During a follow-up period of 12 years, 2872 (64.3%) participants developed dyslipidemia. In non-smoking men, light or moderate alcohol consumption was associated with a lower risk of incident dyslipidemia such as hypertriglyceridemia and hypercholesterolemia, whereas this association was not observed in current smoking men. Unlike non-smokers, the duration of alcohol drinking > 10 years was associated with a higher risk of hypertriglyceridemia in current smoking men (hazard ratio = 1.57, 95% confidence interval: 1.07-2.30, P = 0.020). In addition, alcohol consumption was inversely associated with low HDL-C regardless of smoking status. In women, alcohol consumption was inversely associated with dyslipidemia hypercholesterolemia and low HDL-C regardless of alcohol amount.

CONCLUSION

Smoking crucially confounds the association between long-term alcohol consumption and dyslipidemia, particularly in hypertriglyceridemia and hypercholesterolemia.

Protective effect of smoking cessation on subsequent myocardial infarction and ischemic stroke independent of weight gain: A nationwide cohort study

Smoking cessation reduces the cardiovascular risk but increases body weight. We investigated the risk of subsequent myocardial infarction and ischemic stroke according to weight gain after smoking cessation, using a nationwide population based cohort. We enrolled 3,797,572 Korean adults aged over 40 years who participated in national health screenings between 2009 and 2010. Subjects who quit smoking were classified into three subgroups according to the weight change between baseline and 4 years prior. Myocardial infarctions and ischemic strokes were followed until the end of 2015. We compared the hazard ratios among smoking cessation subgroups, non-smokers, and current smokers. The mean changes in weight (1.5 ± 3.9 kg) of the smoking cessation group were higher than those of the other groups (p < 0.0001). A total of 31,277 and 46,811 subjects were newly diagnosed with myocardial infarction and ischemic stroke, respectively. Regardless of weight change, all subgroups of smoking cessation had significantly less risk than current smokers. The subgroup of smoking cessation with weight gain over 4kg showed the lowest risk for myocardial infarctions (hazard ratio 0.646, 95% confidence interval 0.583-0.714, p < 0.0001) and ischemic strokes (hazard ratio 0.648, 95% confidence interval 0.591-0.71, p < 0.0001) after multivariable adjustment. In conclusion, weight gain after smoking cessation did not adversely affect the cardiovascular protective effect.

Cigarette Smoking: An Accessory to the Development of Insulin Resistance

Insulin resistance is a condition characterized by decreased sensitivity of a skeletal or adipose cell to insulin, resulting in decreased glucose uptake by the cell. This can lead to hyperinsulinemia and further reduce insulin sensitivity. Insulin resistance is one of the primary factors contributing to metabolic syndrome (MetS), causing elevated glucose and fatty acid concentrations in the blood. Smoking is associated with insulin resistance in a dose-dependent manner. It directly increases the risk for insulin resistance, mainly via hormone activation, and may indirectly cause insulin resistance due to its effects on abdominal obesity. Nicotine may be the factor underlying these potential mechanisms. With the prevalence of prediabetes and diabetes on the rise, and considering the role of smoking and its relationship to insulin resistance, smoking reduction or cessation may be a viable option for those who are at risk or already identified as insulin resistant. Therefore, smoking cessation or reduction would serve as a beneficial component in any diabetes prevention or treatment plan.

Associations between behavioural risk factors and smoking, heavy smoking and future smoking among an Australian population-based sample

INTRODUCTION

Tobacco smoking co-occurs with behavioural risk factors including diet, alcohol use and obesity. However, the association between behavioural risk factors and heavy smoking (>20cig/day) compared to light-moderate smoking is unknown. The link between behavioural risk factors and future smoking for both ex and current smokers is also unknown. This study sought to examine these relationships. It is hypothesised that behavioural risk factors will be more strongly associated with heavy smoking.

METHOD

Data from Wave 7 (2007) of the Household and Labour Dynamics in Australia (HILDA) survey was analysed using logistic regression to determine relationships between diet (fruit and vegetable consumption, and unhealthy diet choices), alcohol consumption, obesity and physical activity with light-moderate smoking and heavy smoking. The association between these risk factors and future smoking (2008) was assessed for current and ex-smokers (2007).

RESULTS

Obese respondents were less likely to be light/moderate smokers (RRR: 0.53; 95% CI: 0.43, 0.66) but not heavy smokers. Those who consume confectionary weekly were less likely to be light/moderate smokers (RRR: 0.73; 95% CI: 0.61, 0.87), but not heavy smokers. Smokers in 2007 were more likely to continue smoking in 2008 if they consumed 1-4 drinks per occasion (OR: 2.52; 95% CI: 1.13, 5.62). Ex-smokers in 2007 were less likely to relapse in 2008 if they consumed recommended levels of both fruit and vegetables (OR: 0.31; CI: 0.10, 0.91).

CONCLUSION

The relationships between heavy smoking and behavioural risk factors differ from moderate-light smoking. Future primary care interventions would benefit from targeting multiple risk factors, particularly for heavy smokers.

Relationships among smoking habits, airflow limitations, and metabolic abnormalities in school workers

Background

Chronic obstructive pulmonary disease is caused mainly by habitual smoking and is common among elderly individuals. It involves not only airflow limitation but also metabolic disorders, leading to increased cardiovascular morbidity and mortality.

Objective

We evaluated relationships among smoking habits, airflow limitation, and metabolic abnormalities.

Methods

Between 2001 and 2008, 15,324 school workers (9700 males, 5624 females; age: ≥30 years) underwent medical checkups, including blood tests and spirometry. They also responded to a questionnaire on smoking habits and medical history.

Results

Airflow limitation was more prevalent in current smokers than in ex-smokers and never-smokers in men and women. The frequency of hypertriglyceridemia was higher in current smokers in all age groups, and those of low high-density-lipoprotein cholesterolemia and diabetes mellitus were higher in current smokers in age groups ≥ 40 s in men, but not in women. There were significant differences in the frequencies of metabolic abnormalities between subjects with airflow limitations and those without in women, but not in men. Smoking index was an independent factor associated with increased frequencies of hypertriglyceridemia (OR 1.015; 95% CI: 1.012–1.018; p<0.0001) and low high-density-lipoprotein cholesterolemia (1.013; 1.010–1.016; p<0.0001) in men. Length of smoking cessation was an independent factor associated with a decreased frequency of hypertriglyceridemia (0.984; 0.975–0.994; p = 0.007).

Conclusions

Habitual smoking causes high incidences of airflow limitation and metabolic abnormalities. Women, but not men, with airflow limitation had higher frequencies of metabolic abnormalities.

Intramuscular lipid metabolism in the insulin resistance of smoking

OBJECTIVE

Smoking decreases insulin action and increases the risk of type 2 diabetes in humans. Mechanisms responsible for smoking-induced insulin resistance are unclear. We hypothesized smokers would have increased intramuscular triglyceride (IMTG) and diacylglycerol (DAG) concentration and decreased fractional synthesis rate (FSR) compared with nonsmokers.

RESEARCH DESIGN AND METHODS

Nonsmokers (n = 18, aged 20 +/- 0.5 years, BMI 22 +/- 0.4 kg/m(2), body fat 20 +/- 2%, 0 cigarettes per day) and smokers (n = 14, aged 21 +/- 0.7 years, BMI 23 +/- 0.4 kg/m(2), body fat 20 +/- 3%, 18 +/- 0.7 cigarettes per day) were studied in a fasted condition after a standardized diet. [U-(13)C]palmitate was infused during 4 h of rest followed by a skeletal muscle biopsy and intravenous glucose tolerance test.

RESULTS

Smokers were less insulin sensitive (S(i)) compared with nonsmokers (S(i) 5.28 +/- 0.5 nonsmokers vs. 3.74 +/- 0.3 smokers 10(-4) x microU(-1) x ml(-1), P = 0.03). There were no differences in IMTG or DAG concentration (IMTG 24.2 +/- 3.4 nonsmokers vs. 27.2 +/- 5.9 smokers microg/mg dry wt, DAG 0.34 +/- 0.02 nonsmokers vs. 0.35 +/- 0.02 smokers microg/mg dry wt) or IMTG FSR between groups (0.66 +/- 0.1 nonsmokers vs. 0.55 +/- 0.09 smokers %/hr). Intramuscular lipid composition was different, with increased percent saturation of IMTG (32.1 +/- 1.2 nonsmokers vs. 35.2 +/- 1.0 smokers %, P = 0.05) and DAG (52.8 +/- 1.7 nonsmokers vs. 58.8 +/- 2.2 smokers %, P = 0.04) in smokers. Smokers had significantly decreased peroxisome proliferator-activated receptor-gamma (1.76 +/- 0.1 nonsmokers vs. 1.42 +/- 0.11 smokers arbitrary units [AU], P = 0.03) and increased monocyte chemotactic protein-1 (3.11 +/- 0.41 nonsmokers vs. 4.83 +/- 0.54 smokers AU, P = 0.02) mRNA expression compared with nonsmokers. We also found increased insulin receptor substrate-1 Ser(636) phosphorylation in smokers compared with nonsmokers (0.73 +/- 0.08 nonsmokers vs. 1.14 +/- 0.09 smokers AU, P = 0.002).

CONCLUSIONS

These data suggest: 1) IMTG concentration and turnover are not related to alterations in insulin action in smokers compared to nonsmokers, 2) increased saturation of IMTG and DAG in skeletal muscle may be related to insulin action, and 3) basal inhibition of insulin receptor substrate-1 may decrease insulin action in smokers.

Cigarette smoking associates with body weight and muscle mass of patients with rheumatoid arthritis: a cross-sectional, observational study

Introduction

Rheumatoid arthritis (RA) is associated with altered metabolism leading to muscle wasting. In the general population, cigarette smoking is known to affect body composition by reducing fat and inhibiting muscle synthesis. Even though smoking has been implicated in the pathophysiology and progression of RA, its possible effects on body composition of such patients have not been studied. This cross-sectional study aimed to identify potential associations of smoking with body weight and composition of RA patients.

Methods

A total of 392 patients (290 females) with RA were assessed for body mass index (BMI), body fat (BF), fat-free mass (FFM), and waist circumference. Erythrocyte sedimentation rate, C-reactive protein, Disease Activity Score-28, and Health Assessment Questionnaire score were used to assess disease activity and severity. Smoking habit (current smoker, ex-smoker, or never-smoker) and intensity (pack-years) were also noted.

Results

Current smokers had a significantly lower BMI compared with ex-smokers (mean difference: male -2.6, 95% confidence interval [CI]: -3.5 to -1.7; female: -2.6, 95% CI: -4.8 to -0.5) and never-smokers (mean difference: male -1.8, 95% CI: -3 to -0.6; female: -1.4, 95% CI: -2.4 to -0.4). Similarly, the BF of current smokers was lower compared with that of ex-smokers (mean difference: male: -4.3, 95% CI: -7.5 to -1.2; female: -3.4, 95% CI: -6.4 to -0.4) and never-smokers (mean difference: male: -3.3, 95% CI: -6.3 to -0.4; female: -2.1, 95% CI: -4 to -0.2). FFM did not differ between groups. Finally, current smokers had a significantly smaller waist circumference compared with ex-smokers only (mean difference: male: -6.2, 95% CI: -10.4 to -1.9; female: -7.8, 95% CI: -13.5 to -2.1). Following adjustments for age, disease duration, and HAQ score, smoking remained a significant predictor for BMI (P < 0.001), BF (P < 0.05), and waist circumference (P < 0.05). Pack-years were inversely correlated with BF (r = -0.46; P < 0.001), and heavy smokers exhibited a significantly lower FFM (P < 0.05) compared with all other participants.

Conclusion

Within the limitations of a cross-sectional study, it appears that cigarette smoking associates with reduced BMI and BF in patients with RA and heavy smoking associates with lower muscle mass. Smoking cessation appears to associate with increased BMI, BF, and waist circumference in these patients. These results should be confirmed in prospective studies. Given the numerous adverse effects of smoking on general health and RA, patients should be actively advised against it. However, smoking cessation regimes in RA may need to include more general lifestyle counselling, particularly about weight control.

Smoking and smoking cessation -- the relationship between cardiovascular disease and lipoprotein metabolism: a review

Cigarette smoking is generally accepted as the most preventable cause of death in the United States today. Individuals who smoke experience a wide range of physiologic side effects that increase the risk of cardiovascular disease (CVD), including insulin resistance, elevated catecholamine levels which contribute to an elevated heart rate and blood pressure, and hypercholesterolemia. The link between hypercholesterolemia and cardiovascular disease has been extensively researched and is undeniable. What is more, this link is strengthened in smokers as cigarette smoking is known to increase total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL), while acting to decrease the cardio-protective high-density lipoprotein (HDL). Alterations in the enzymes that control lipid transport may be a key underlying mechanism contributing to these health destroying effects. This review examines the current literature related to: (1) smoking, lipoproteins, and lipid-related enzymes; (2) the impact of nicotine, carbon monoxide and free radicals on physiologic parameters related to health; and (3) metabolic issues involving smoking cessation and nicotine replacement therapy.

Acute in vivo chylomicron metabolism and postalimentary lipoprotein alterations in normolipidemic male smokers

Increased postprandial lipemia has been stated as one of the mechanisms responsible for atherogenesis in smokers. We measured the postalimentary lipid response and the in vivo intravascular delipidation index of an artificial chylomicron emulsion in healthy adult smokers and controls. The blood was collected in the fasting state immediately after the smokers smoked one cigarette. The lipemia was measured 2, 4, 6 and 8 h postalimentarily in smokers (S, n = 8) and in non-smoking controls (C, n = 8) and the chylomicron metabolism rate was measured 2, 4, 6, 8, 12, 16, 20, 24 and 30 min after the injection of an artificial emulsion to S (n = 10) and to C (n = 10). The lipoproteins were isolated in the fasting period and 4 h after the fatty meal and their chemical composition in cholesterol, triglycerides, phospholipids and protein was determined. Smokers showed an increased lipolysis percentage value (mean +/- S.E.M.) of the artificial chylomicron (39.1 +/- 3.1) compared to controls (26.5 +/- 3.3) and higher levels of HDL(2)-PL: 28.4 +/- 4.3 (S) versus 16.2 +/- 2.0 (C) mg/dl (mean +/- S.E.M.). In conclusion, the oral fat tolerance was not altered in smokers but an upregulation of the rate of metabolism of the TG-rich lipoproteins was elicited immediately after smoking one cigarette.

A prospective study of the effects of changes in smoking habits on blood count, serum lipids and lipoproteins, body weight and blood pressure in occupationally active men. The Israeli CORDIS Study

In cross-sectional studies, significant differences in cardiovascular disease risk factors have been observed between smokers and non-smokers. The aim of this study was to examine the effects of smoking initiation and cessation on these factors in a population-based prospective study. 987 male employees in Israeli industry underwent health screening in the CORDIS study and were re-examined an average of two and a half years later. We examined the associations between smoking initiation and cessation and changes in blood count, serum lipids and lipoproteins, body weight and blood pressure. After adjusting for potential confounders, smoking cessation was associated with significant decreases in leukocyte count, hemoglobin and hematocrit whereas smoking initiation resulted in increased leukocyte count. There were moderate, non-significant increases in both serum HDL cholesterol (HDL-C) and LDL-C, and a slight decrease in serum triglycerides. Blood pressure remained essentially unchanged, despite the fact that smoking cessation resulted in a significant weight increase and smoking initiation in a significant decline in weight. These findings demonstrate that changes in smoking habits result in fairly rapid changes in blood count and body weight, but have much smaller effects on serum lipids and blood pressure.

Lipid intolerance in smokers

OBJECTIVES

Smokers have recently been shown to be insulin resistant and to exhibit several characteristics of the insulin resistance syndrome (IRS). In this study, we assessed fasting and postprandial lipid levels in healthy, normolipidaemic, chronic smokers and a matched group of non-smoking individuals.

DESIGN

A standardized mixed meal (containing 3.78 MJ and 51 g of fat) was given in the morning after an overnight fast. The smokers were either abstinent from tobacco for 48 h or were allowed to smoke freely, including being allowed to smoke six cigarettes during the study.

SUBJECTS

Twenty-two middle-aged, healthy male subjects, nine habitual smokers and 13 non-smoking control subjects, were recruited to the study. The smokers had all been smoking at least 10 cigarettes per day for at least 10 years.

RESULTS

The smokers exhibited a lipid intolerance in that their postprandial increase in triglyceride levels was more than 50% higher than in the non-smokers' group. This lipid intolerance could not be discerned in the postabsorptive state because the fasting triglyceride levels were the same in both groups, while the smokers had significantly lower high-density lipoprotein (HDL) cholesterol. The peak postprandial triglyceride level correlated closely and negatively with fasting HDL cholesterol, indicating an impaired lipolytic removal capacity in smokers.

CONCLUSIONS

Healthy, normotriglyceridaemic smokers exhibit an abnormal postprandial lipid metabolism consistent with lipid intolerance. It is suggested that postprandial hyperlipidaemia is a characteristic trait of the insulin resistance syndrome and that the defect in lipid removal is related to the low HDL cholesterol in this syndrome. The insulin resistance syndrome is likely to be an important reason for the increased propensity for cardiovascular disease in smokers.

Metabolic effects of nicotine on human adipose tissue in organ culture

Fragments of human adipose tissue were maintained in culture for 1 week in a medium containing 1 mU/ml insulin and 100 ng/ml dexamethasone. Under these conditions lipoprotein lipase activity was present in human adipose tissue fragments which converted [14C]glucose to 14CO2 and [14C]triglyceride. Both metabolic parameters studied were affected by human tumor necrosis factor and brefeldin A. When fragments of human adipose tissue after 1 week in culture were incubated with nicotine tartrate for 20 h, a slight but significant increase in lipoprotein lipase activity was observed, and an increased conversion of [14C]glucose to 14CO2 and [14C]triglyceride occurred. Nicotine was taken up by human adipose tissue, but no conversion to cotinine was observed. Our data demonstrate a direct effect of nicotine on human adipose tissue metabolism. Furthermore, it is suggested that weight loss in smokers is a multifactorial phenomenon, and one of the important factors to be considered is the direct effect of nicotine within the tissue.

Effects of cigarette smoking and its cessation on lipid metabolism and energy expenditure in heavy smokers

The relationship between thermogenic and potentially atherogenic effects of cigarette smoking (CS) and its cessation was investigated. Heavy smokers (n = 7, serum cotinine > 200 ng/ml, > 20 cigarettes/d) were maintained on isoenergetic, constant diets for 2 wk, 1 wk with and 1 wk without CS. Stable isotope infusions with indirect calorimetry were performed on day 7 of each phase, after an overnight fast. CS after overnight abstention increased resting energy expenditure by 5% (not significant vs. non-CS phase; P = 0.18). CS increased the flux of FFA by 77%, flux of glycerol by 82%, and serum FFA concentrations by 73% (P < 0.02 for each), but did not significantly affect fat oxidation. Hepatic reesterification of FFA increased more than threefold (P < 0.03) and adipocyte recycling increased nonsignificantly (P = 0.10). CS-induced lipid substrate cycles represented only 15% (estimated 11 kcal/d) of observed changes in energy expenditure. De novo hepatic lipogenesis was low (< 1-2 g/d) and unaffected by either acute CS or its chronic cessation. Hepatic glucose production was not affected by CS, despite increased serum glycerol and FFA fluxes. Cessation of CS caused no rebound effects on basal metabolic fluxes. In conclusion, a metabolic mechanism for the atherogenic effects of CS on serum lipids (increased hepatic reesterification of FFA) has been documented. Increased entry of FFA accounts for CS-induced increases in serum FFA concentrations. The thermogenic effect of CS is small or absent in heavy smokers while the potentially atherogenic effect is maintained, and cessation of CS does not induce a rebound lipogenic milieu that specifically favors accrual of body fat in the absence of increased food intake.

Metabolic and behavioral covariates of high-density lipoprotein cholesterol and triglyceride concentrations in postmenopausal women

OBJECTIVE

To determine predictors of high-density lipoprotein cholesterol (HDL) and triglyceride (TG) concentrations in postmenopausal women.

DESIGN

Cross-sectional study.

SETTING

Clinical research facility.

PARTICIPANTS

One hundred twenty-seven healthy, relatively sedentary, postmenopausal women not on estrogen replacement, mean age 57 years.

MEASUREMENTS

Alcohol intake, cigarette smoking, aerobic fitness (VO2max), body mass index (BMI), percent body fat, waist-hip ratio, lipids and lipoproteins, fasting plasma glucose (FPG), and insulin (FPI) concentrations.

RESULTS

In univariate analyses, HDL was significantly (P < 0.05) inversely related to BMI, waist-hip ratio, smoking, FPG, and FPI, and directly related to VO2max and alcohol intake. Triglycerides were related directly to BMI, waist-hip ratio, percent body fat, FPG, and FPI, and inversely to VO2max. In stepwise multiple regressions, BMI, waist-hip ratio, alcohol, smoking, and FPG were significantly associated with HDL (R2 for the model = 0.43). Addition of TG to these models reduced relations of BMI and waist-hip ratio, but not the other variables, to insignificance. For triglycerides, waist-hip ratio, alcohol, smoking, FPG, and FPI were significant predictors (R2 = 0.33). VO2max and percent body fat did not contribute to any model.

CONCLUSIONS

Obesity, abdominal obesity, smoking, alcohol intake, and measures of carbohydrate metabolism predict HDL and triglyceride concentrations in postmenopausal women.

Coronary risk factors in middle-aged men as related to smoking, coffee intake and physical activity

The relationship between lifestyle and coronary risk factors in blood was investigated in 165 middle-aged men. Plasma fibrinogen, serum triacylglycerols (TG), and apolipoprotein B (apo B) were higher, and high density lipoprotein cholesterol (HDLc) lower in smokers (n = 69) than in non-smokers (n = 96). By linear regression analysis there was a significant positive association between degree of smoking and either total cholesterol (TC), apo B, or plasma fibrinogen, whereas smoking was inversely related to HDLc. Smoking and coffee intake were positively correlated with an atherogenic index, reflecting the balance between low and high density lipoproteins. Sedentary men (n = 59) had higher mean TC, apo B, and atherogenic index than physically active men (n = 104). Smokers used salt more often than non-smokers. Physically active men used vegetables more often than sedentary men. Combining several habits into a "bad habit" score gave a high level of significance for its association with TC, apo B, and the atherogenic index. The results indicate that lifestyle may influence several blood factors involved in atherosclerosis development.