The relationship between insulin resistance and dyslipidaemia in cigarette smokers

Electronic Cigarette Use and the Risk of Cardiovascular Diseases

Electronic cigarettes or e-cigarettes are the most frequently used tobacco product among adolescents. Despite the widespread use of e-cigarettes and the known detrimental cardiac consequences of nicotine, the effects of e-cigarettes on the cardiovascular system are not well-known. Several in vitro and in vivo studies delineating the mechanisms of the impact of e-cigarettes on the cardiovascular system have been published. These include mechanisms associated with nicotine or other components of the aerosol or thermal degradation products of e-cigarettes. The increased hyperlipidemia, sympathetic dominance, endothelial dysfunction, DNA damage, and macrophage activation are prominent effects of e-cigarettes. Additionally, oxidative stress and inflammation are unifying mechanisms at many levels of the cardiovascular impairment induced by e-cigarette exposure. This review outlines the contribution of e-cigarettes in the development of cardiovascular diseases and their molecular underpinnings.

Cardiovascular risk may be increased in women with unexplained infertility

Objective

Growing evidence suggests that increased cardiovascular disease (CVD) risk is associated with female infertility caused by conditions such as polycystic ovarian disease, obesity, thyroid dysfunction, and endometriosis. The aim of this study was to evaluate whether any relationship exists between CVD and unexplained infertility.

Methods

Sixty-five women with unexplained infertility and 65 fertile controls were enrolled in the study. CVD risk markers such as low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC), triglycerides (TG), insulin resistance (defined by the homeostasis model assessment ratio), and high-sensitivity C-reactive protein (hs-CRP) were assessed.

Results

TG, TC, LDL, and hs-CRP levels were higher and HDL levels were lower in patients with unexplained infertility than in fertile controls (p<0.05 for all). Positive associations were found between unexplained infertility and TG, TC, LDL, and hs-CRP levels, and a negative correlation was found for HDL (p<0.05 for all). Multivariate logistic regression analysis showed that TG, HDL, and hs-CRP were independent variables associated with unexplained infertility.

Conclusion

Our study showed that women with unexplained infertility had an atherogenic lipid profile and elevated hs-CRP levels, suggesting a higher risk of developing CVD in the future. Further studies with larger groups are needed to investigate the nature of this link.

Is there any relationship between cardiovascular risk markers and young women with diminished ovarian reserve?

OBJECTIVE

It has been widely known that cardiovascular disease (CVD) risk is increased in menopause. The aim of the study was to evaluate whether this risk was elevated in young women with diminished ovarian reserve (DOR).

METHODS

A hundred women with DOR and 100 women with normal ovarian reserve (NOR) attending the infertility unit at Suleymaniye Maternity, Research &Training Hospital, were enrolled in the study. CVD risk markers such as insulin resistance (defined by the homeostasis model assessment ratio [HOMA-IR]), C-reactive protein (CRP), low-density lipoprotein (LDL), high-density lipoprotein (HDL), total cholesterol (TC), and triglyceride (TG) were assessed.

RESULTS

HOMA-IR, CRP, TG, LDL levels were higher and HDL was lower among patients with DOR compared to the controls (p < 0.05 for all). There were positive associations between DOR and HOMA-IR, CRP, TG, LDL levels and a negative correlation with HDL (p < 0.05 for all). However, multivariate logistic regression analysis showed that HOMA-IR, CRP, TG, and HDL were independent variables that were associated with DOR.

CONCLUSIONS

CVD risk markers were increased in women with DOR. Further studies with larger groups are needed to investigate the nature of the link in these patients.

Smoking was a Possible Negative Predictor of Incident Hypertension After a Five-Year Follow-up Among a General Japanese Population

BACKGROUNDS

The association between cigarette smoking and hypertension is controversial. The aim of this study is to investigate the association between smoking and incident hypertension.

METHODS

This is a post-hoc five-year follow-up study in a general Japanese population. Logistic regressions were performed using incident hypertension as an outcome and smoking status as an independent predictor adjusting for sex, age, body mass index (BMI), total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, fasting plasma glucose (FPG), drinking status, and diabetes in 1,297 subjects without hypertension at baseline.

RESULTS

The incidence of hypertension was 16.9% vs. 27.6% (smokers vs. nonsmokers, P = 0.01) in men and 0.0% vs. 16.9% (smokers vs. nonsmokers, P = 0.03) in women. The odds ratio (OR) (95% confidence interval (CI)) of incident hypertension was 0.38 (0.19 - 0.76) (P = 0.006) for smokers at baseline, 0.33 (0.16 - 0.68) (P = 0.003) for continuing smokers, and 2.11 (0.33 - 13.45) (P = 0.4) for ex-smokers. Age (OR = 1.52, P < 0.0001), BMI (OR = 1.46, P < 0.0001), and FPG (OR = 1.23, P = 0.007) were other independent predictors of incident hypertension.

CONCLUSIONS

Smoking was a possible significant negative predictor of incident hypertension in a general Japanese population.

Bilirubin is negatively associated with hemoglobin a(1c) independently of other cardiovascular risk factors in apparently healthy Japanese men and women

BACKGROUND

Serum total bilirubin (TB) is a potent antioxidant and may be a negative risk factor of cardiovascular disease. In non-diabetic adults, hemoglobin A(1c) (HbA(1c)), but not fasting plasma glucose, is an independent risk factor of cardiovascular disease.

METHODS AND RESULTS

Linear regression using TB as a dependent variable and cardiovascular risk factors, including HbA(1c), as independent variables, linear regression using HbA(1c) as a dependent variable and other cardiovascular risk factors, including TB, as independent variables, and logistic regression using the highest decile (≥ 5.4%) of HbA(1c) as a dependent variable and TB and other cardiovascular risk factors as independent variables were performed for 893 apparently healthy male smokers, 1,607 male nonsmokers, and 1,680 women. The standardized regression coefficient of HbA(1c) for TB and that of TB for HbA(1c) was -0.12 (P = 0.007) and -0.06 (P = 0.02), respectively, in the smokers, -0.20 (P < 0.0001) and -0.07 (P < 0.0001), respectively, in the nonsmokers, and -0.21 (P < 0.0001) and -0.14 (P < 0.0001), respectively, in the women. The odds ratio of 1 SD increment in TB for HbA(1c) ≥ 5.4% was not significant in the smokers, 0.67 (P = 0.002) in the nonsmokers, and 0.55 (P<0.0001) in the women.

CONCLUSIONS

Bilirubin was negatively associated with HbA(1c) independently of other cardiovascular risk factors in apparently healthy Japanese men and women. The association was weak in male smokers.

Pioglitazone decreases postprandial accumulation of remnant lipoproteins in insulin-resistant smokers

BACKGROUND

Fasting hypertriglyceridaemia has been reported to occur commonly in cigarette smokers and is thought to increase cardiovascular disease (CVD) risk in these individuals. More recently, it has been suggested that an increase in non-fasting triglycerides, rather than fasting hypertriglyceridaemia, is an independent CVD risk factor.

METHODS

In this study, we divided 24 smokers into insulin-resistant (IR) and insulin-sensitive (IS) groups by determining their steady-state plasma glucose concentrations during the insulin suppression test and compared fasting and daylong postprandial accumulation of total triglycerides and remnant lipoprotein (RLP) concentrations, before and after 3 months of pioglitazone (PIO) administration.

RESULTS

The two groups were similar in age, body mass index, race and gender distribution, but differed dramatically in insulin sensitivity. Baseline fasting and postprandial triglyceride, RLP cholesterol and RLP triglyceride concentrations were significantly higher in the IR smokers (p=0.01 to <0.01). Insulin resistance [corrected] and both fasting and postprandial triglyceride and RLP triglyceride levels decreased significantly (p=0.05 to 0.01) [corrected] in PIO-treated IR smokers, without any significant increase in weight instead of insulin sensitivity and both fasting and postprandial triglyceride and RLP triglyceride levels decreased significantly (p = 0.05 to, 0.01) in PIO-treated IR smokers, without any significant increase in weight. [corrected]

CONCLUSIONS

The postprandial accumulation of RLP particles is increased in the IR subset of smokers and is likely to contribute to the increased CVD risk in these individuals. Furthermore, PIO administration provides a possible therapeutic approach to decreasing postprandial lipaemia and CVD risk in IR smokers who are unwilling or unable to stop smoking.

Relation of plasma lipoprotein levels with low-grade inflammation in white men without clinical evidence of myocardial ischemia

There is a growing body of evidence indicating that high triglyceride levels are an independent risk factor for cardiovascular disease (CVD) events. In this study we compared the association of fasting levels of non-high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, HDL cholesterol, and triglycerides with white blood cell (WBC) count, an inflammatory marker associated with an adverse CVD prognosis. We studied 458 asymptomatic men (46.0 +/- 7.0 years old) who presented for CVD risk stratification. WBC count (x10(9) cells/L) increased significantly across increasing tertiles of triglyceride level (tertile 1, 6.04 +/- 1.49; tertile 2 6.21 +/- 1.44; tertile 3 6.78 +/- 1.73, p <0.0001), whereas a trend of lower WBC counts was observed across increasing tertiles of HDL cholesterol (tertile 1, 6.52 +/- 1.62; tertile 2, 6.24 +/- 1.50; tertile 3, 6.21 +/- 1.61, p = 0.08). In models adjusted for age, gender, and CVD risk factor, the odds ratio for a high WBC count (quartile > or =4 vs lower 3 quartiles) was significantly higher with increasing levels of triglyceride (2.4, 95% confidence interval 1.3 to 4.8, p = 0.02). When all lipid variables were introduced in the models in addition to traditional CVD risk factors, the association between plasma triglyceride level and WBC count persisted (p = 0.04), which was not found for other lipid parameters. In conclusion, in our study, only plasma triglyceride level was independently associated with a higher WBC count.