Sex, plasma lipoproteins, and atherosclerosis: prevailing assumptions and outstanding questions

Association Between Remnant Cholesterol and Risk of Incident Atrial Fibrillation: Population-Based Evidence From a Large-Scale Prospective Cohort Study

BACKGROUND

Evidence for the relationship between remnant cholesterol (RC) and incident atrial fibrillation (AF) risk remains sparse and limited.

METHODS AND RESULTS

Participants were enrolled between 2006 and 2010 and followed up to 2021. The multivariable Cox proportional hazards model was used to examine the relationship between RC quartiles and risk of incident AF. Subgroup analyses and sensitivity analyses were performed to explore the potential modification of the association and the robustness of the main findings. A total of 422 316 participants (mean age, 56 years; 54% women) were included for analyses. During a median follow-up of 11.9 years (first quartile-third quartile, 11.6-13.2 years), there were 24 774 AF events documented with an incidence of 4.92 events per 1000 person-years (95% CI, 4.86-4.98). Participants in higher RC quartiles had a lower risk of incident AF than those in the lowest quartile (first quartile): hazard ratio (HR)=0.96 (95% CI, 0.91-1.00) for second quartile; HR=0.92 (95% CI, 0.88-0.96) for third quartile; and HR=0.85 (95% CI, 0.81-0.89) for fourth quartile (P for trend <0.001). The association between RC quartiles and risk of incident AF was stronger in participants aged ≥65 years, in men, and in participants without history of diabetes when compared with control groups (P<0.001 for interaction).

CONCLUSIONS

On the basis of data from this large-scale prospective cohort study, elevated RC was associated with a lower risk of incident AF.

Effect of biological sex on human circulating lipidome: An overview of the literature

Cardiovascular diseases (CVD) are the leading cause of death worldwide for both men and women, but their prevalence and burden show marked sex differences. The existing knowledge gaps in research, prevention, and treatment for women emphasize the need for understanding the biological mechanisms contributing to the sex differences in CVD. Sex differences in the plasma lipids that are well-known risk factors and predictors of CVD events have been recognized and are believed to contribute to the known disparities in CVD manifestations in men and women. However, the current understanding of sex differences in lipids has mainly come from the studies on routinely measured standard lipids- low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total triglycerides, and total cholesterol, which have been the mainstay of the lipid profiling. Sex differences in individual lipid species, collectively called the lipidome, have until recently been less explored due to the technological challenges and analytic costs. With the technological advancements in the last decade and growing interest in understanding mechanisms of sexual dimorphism in metabolic disorders, many investigators utilized metabolomics and lipidomics based platforms to examine the effect of biological sex on detailed lipidomic profiles and individual lipid species. This review presents an overview of the research on sex differences in the concentrations of circulating lipid species, focusing on findings from the metabolome- and lipidome-wide studies. We also discuss the potential contribution of genetic factors including sex chromosomes and sex-specific physiological factors such as menopause and sex hormones to the sex differences in lipidomic profiles.

Sex Difference in the Association between Lipid Profile and Incident Cardiovascular Disease among Young Adults

AIM

Using a nationwide epidemiological database, we sought to examine whether there was a sex difference in the association between lipid profiles and subsequent cardiovascular disease (CVD) in young adults.

METHODS

Medical records of 1,909,362 young adults (20-49 years old) without a prior history of CVD and not taking lipid-lowering medications were extracted. We conducted multivariable Cox regression analyses to identify the association between the number of abnormal lipid profiles and incident CVD.

RESULTS

After a mean follow-up of 3.4±2.6 years, myocardial infarction (MI), angina pectoris (AP), stroke, and heart failure (HF) developed in 2,575 (0.1%), 26,006 (1.4%), 10,748 (0.6%), and 24,875 (1.3%) subjects, respectively. The incidence of MI, AP, and HF increased with the number of abnormal lipid profiles in both men and women, whereas the incidence of stroke increased with the number of abnormal lipid profiles only in men but not in women. Multivariable adjusted hazard ratios (HRs) for MI per 1-point higher abnormal lipid profile were 1.57 (95% confidence interval [CI] 1.49-1.65) in men and 1.25 (95% CI 1.07-1.47) in women. HRs for AP, stroke, and HF per 1-point higher abnormal lipid profile were 1.14 (95% CI 1.12-1.16), 1.06 (95% CI 1.02-1.09), and 1.10 (95% CI 1.08-1.12) in men and 1.18 (95% CI 1.13-1.23), 1.09 (95% CI 1.03-1.16), and 1.10 (95% CI 1.05-1.14) in women.

CONCLUSION

Our analysis demonstrated an association between the number of abnormal lipid profiles and incident CVD in both men and women. The association between the number of abnormal lipid profiles and incident MI was pronounced in men.

Comparing dietary score associations with lipoprotein particle subclass profiles: A cross-sectional analysis of a middle-to older-aged population

BACKGROUND AND OBJECTIVES

Lipoprotein particle concentrations and size are associated with increased risk for atherosclerosis and premature cardiovascular disease. Studies also suggest that certain dietary behaviours may be cardioprotective. Limited comparative data regarding any dietary score/index-lipoprotein particle subclass associations exist. Thus, our objective was to assess relationships between the Dietary Approaches to Stop Hypertension (DASH), Health Eating Index-2015 (HEI-2015), Mediterranean Diet (MD) and Energy-adjusted Dietary Inflammatory Index (E-DII™) scores and plasma lipids and lipoprotein profiles to test the hypothesis that healthier diet (better quality and more anti-inflammatory) would be associated with a more favourable lipoprotein profile.

MATERIALS AND METHODS

This was a cross-sectional study of 1862 men and women aged 46-73 years, randomly selected from a large primary care centre in Ireland. DASH, HEI-2015, MD and E-DII scores were derived from food frequency questionnaires. Lipoprotein subclass particle concentrations and size were determined using nuclear magnetic resonance spectroscopy. Correlation and multivariate-adjusted linear regression analyses with correction for multiple testing were performed to examine dietary score relationships with lipoprotein particle subclasses.

RESULTS

In fully adjusted models, higher diet quality or a more anti-inflammatory diet was associated with less large and medium very low-density lipoprotein (VLDL) (DASH and HEI-2015), intermediate-density lipoprotein (IDL) (DASH, MD and E-DII) and small high-density lipoprotein (HDL) (DASH, HEI-2015 and E-DII) particles. After accounting for multiple testing, relationships with large VLDL (DASH: β = -0.102, p = .037), IDL (DASH: β = -0.089, p = .037) and small HDL (DASH: β = -0.551, p = .014 and E-DII: β = 0.483, p = .019) concentrations persisted.

CONCLUSIONS

These findings provide evidence that better diet quality, determined by the DASH score, may be more closely associated with a more favourable lipoprotein particle subclass profile in middle-to older-aged adults than the HEI-2015, MD and E-DII scores. A less pro-atherogenic lipoprotein status may be a potential mechanism underlying the cardioprotective effects of higher dietary quality.

Chronic Fructose Substitution for Glucose or Sucrose in Food or Beverages and Metabolic Outcomes: An Updated Systematic Review and Meta-Analysis

Despite the publication of several of meta-analyses in recent years, the effects of fructose on human health remains a topic of debate. We previously undertook two meta-analyses on post-prandial and chronic responses to isoenergetic replacement of fructose for sucrose or glucose in food or beverages (Evans et al. 2017, AJCN 106:506–518 & 519–529). Here we report on the results of an updated search with a complete re-extraction of previously identified studies and a new and more detailed subgroup-analysis and meta-regression. We identified two studies that were published after our previous analyses, which slightly altered effect sizes and conclusions. Overall, the isoenergetic substitution of fructose for glucose resulted in a statistically significant but clinically irrelevant reduction in fasting blood glucose, insulin, and triglyceride concentrations. A subgroup analysis by diabetes status revealed much larger reductions in fasting blood glucose in people with impaired glucose tolerance and type 2 diabetes. However, each of these subgroups contained only a single study. In people with a healthy body mass index, fructose consumption was associated with statistically significant, but clinically irrelevant reductions in fasting blood glucose and fasting blood insulin. Meta-regression of the outcomes by a number of pre-identified and post-hoc covariates revealed some sources of heterogeneity, such as year of publication, age of the participants at baseline, and participants' sex. However, the small number of studies and the large number of potential covariates precluded detailed investigations of effect sizes in different subpopulations. For example, well-controlled, high quality studies in people with impaired glucose tolerance and type 2 diabetes are still lacking. Taken together, the available data suggest that chronic consumption of fructose is neither more beneficial, nor more harmful than equivalent doses of sucrose or glucose for glycemic and other metabolic outcomes.

The Effects of Androgens on Cardiometabolic Syndrome: Current Therapeutic Concepts

INTRODUCTION

Cardiometabolic syndrome (CMS), as a bunch of metabolic disorders mainly characterized by type 2 diabetes mellitus (T2DM), hypertension, atherosclerosis, central adiposity, and abdominal obesity triggering androgen deficiency, is one of the most critical threats to men. Although many significant preclinical and clinical findings explain CMS, new approaches toward common pathophysiological mechanisms and reasonable therapeutic targets are lacking.

AIM

To gain a further understanding of the role of androgen levels in various facets of CMS such as the constellation of cardiometabolic risk factors including central adiposity, dyslipidemia, insulin resistance, diabetes, and arterial hypertension and to define future directions for development of effective therapeutic modalities.

METHODS

Clinical and experimental data were searched through scientific literature databases (PubMed) from 2009 to October 2019.

MAIN OUTCOME MEASURE

Evidence from basic and clinical research was gathered with regard to the causal impact and therapeutic roles of androgens on CMS.

RESULTS

There are important mechanisms implicated in androgen levels and the risk of CMS. Low testosterone levels have many signs and symptoms on cardiometabolic and glycometabolic risks as well as abdominal obesity in men.

CLINICAL IMPLICATIONS

The implications of the findings can shed light on future improvements in androgen levels and add potentially predictive risk for CMS, as well as T2DM, abdominal obesity to guide clinical management in the early stage.

STRENGTHS & LIMITATIONS

This comprehensive review refers to the association between androgens and cardiovascular health. A limitation of this study is the lack of large, prospective population-based studies that analyze the effects of testosterone treatment on CMS or mortality.

CONCLUSION

Low testosterone levels have several common features with metabolic syndrome. Thus, testosterone may have preventive role in the progress of metabolic syndrome and subsequent T2DM, abdominal obesity, and cardiovascular disease and likely affect aging men's health mainly through endocrine and vascular mechanisms. Further studies are necessary to evaluate the therapeutic interventions directed at preventing CMS in men. Kirlangic OF, Yilmaz-Oral D, Kaya-Sezginer E, et al. The Effects of Androgens on Cardiometabolic Syndrome: Current Therapeutic Concepts. Sex Med 2020;8:132-155.

Effects of tibolone or continuous combined oestradiol and norethisterone acetate on lipids, high-density lipoprotein subfractions and apolipoproteins in postmenopausal women in a two-year, randomized, double-blind, placebo-controlled trial

OBJECTIVE

To compare the effects of (a) tibolone, (b) continuous combined oestrogen plus progestogen and (c) placebo on plasma lipid and lipoprotein markers of cardiovascular risk in healthy postmenopausal women.

STUDY DESIGN

Randomized, single-centre, placebo-controlled, double-blind study.

PATIENTS

One hundred and one postmenopausal women were randomized (1:1:1) into one of three groups taking daily 2.5 mg tibolone, continuous oral oestradiol-17β 2 mg plus norethisterone acetate 1 mg daily (E₂ /NETA) or placebo.

MAIN OUTCOME MEASURES

Fasting serum lipid, lipoprotein and apolipoprotein concentrations measured at baseline and after 6, 12 and 24 months of treatment.

RESULTS

Both tibolone and E₂ /NETA lowered plasma total cholesterol concentrations relative to placebo. With tibolone, high-density lipoprotein cholesterol (HDL-C) was reduced (-27% at 24 months, P < .001), the greatest effect being in the cholesterol-enriched HDL₂ subfraction (-40%, P < .001). Tibolone's effect on HDL concentrations was also apparent in the principal HDL protein component, apolipoprotein AI (-29% at 24 months, P < .001). However, there was no significant effect of tibolone on low-density or very low-density lipoprotein cholesterol (LDL-C and VLDL-C, respectively). By contrast, the greatest reduction in cholesterol with E₂ /NETA was in LDL-C (-22% at 24 months, P = .008). E₂ /NETA reduced HDL-C to a lesser extent than tibolone (-12% at 24 months, P < .001). Effects on HDL apolipoproteins were similarly diminished relative to tibolone. E₂ /NETA had no effect on VLDL-C or on the protein component of LDL, apolipoprotein B.

CONCLUSION

Tibolone reduces serum HDL. E₂ /NETA reduces LDL cholesterol but not apolipoprotein B, suggesting decreased cholesterol loading of LDL. Any impact these changes may have on CVD risk needs further investigation.

Cardiometabolic risk factors in Thai individuals with prediabetes treated in a high-risk, prevention clinic: Unexpected relationship between high-density lipoprotein cholesterol and glycemia in men

AIMS/INTRODUCTION

Relationships between cardiometabolic risk and glycemia have rarely been studied in people under clinical evaluation and treatment for cardiometabolic risk and with prediabetes. We investigated relationships between glycemia and cardiometabolic risk factors in clinic participants with prediabetes.

MATERIALS AND METHODS

This was a cross-sectional analysis of data collected at a center in Thailand. Clinic attendees were at high risk of diabetes or cardiovascular disease, with hemoglobin A1c (HbA1c) 39-<48 mmol/mol or fasting plasma glucose (FPG) 5.6-<7.0 mmol/L. The relationships between glycemia and cardiometabolic risk factors were explored.

RESULTS

Of 357 participants, two or more insulin resistance-related metabolic disturbances were present in 84%; 61% took a statin and 75% an antihypertensive agent. Independently of age, sex, adiposity, medication use, possible non-alcoholic fatty liver disease and sex-glycemia interaction, neither FPG nor HbA1c were associated with variation in any other cardiometabolic risk factors. High-density lipoprotein cholesterol decreased with HbA1c in women (female-HbA1c interaction, P = 0.03) but, unexpectedly, increased with FPG in men (male-FPG interaction, P = 0.02).

CONCLUSIONS

Overall, in Thai people treated for high cardiometabolic risk and with prediabetes defined by FPG and/or HbA1c, neither FPG nor HbA1c were associated with other cardiometabolic risk factors. However, according to sex, high-density lipoprotein cholesterol showed the expected relationship with glycemia in women, but the reverse in men.

Age, Sex, and Cardiovascular Risk Attributable to Lipoprotein Cholesterol Among Chinese Individuals with Coronary Artery Disease: A Case-Control Study

Aim: To understand age- and gender-related differences and secular trends in coronary artery disease (CAD) lipid profiles and the characteristic of dyslipidemia in western China. Methods: An age-matched case-control study, including 2400 patients and 1200 controls was performed. All blood lipid tests evaluated from January 2012 to January 2015 at First Affiliated Hospital of Xinjiang Medical University were analyzed. Details of the gender and age of the patients were available. Trends were calculated using linear regression and Mantel-Haenszel X² analyses. Results: We determined the associations among total cholesterol (TC), triglycerides (TGs), low-density lipoprotein cholesterol (LDL-C), apolipoprotein A-1 (apoA-1), apolipoprotein B (apoB), nonhigh-density lipoprotein cholesterol (non-HDL-C), and high-density lipoprotein cholesterol (HDL-C) with CAD for different ages and gender. Except for patients who were <40 years old, the plasma levels of TC, TG, LDL-C, non-HDL-C, apoB, and apoB/apoA-1 were higher in the cases than in controls, and the average levels of these markers decreased significantly as age increased. In contrast, the levels of apoA-1 and HDL-C were significantly higher in the controls than in the patients, and the levels of these markers significantly increased as age increased. Women had higher levels of TC, LDL-C, non-HDL-C, and apoB and a higher value of the apoB/apoA-1 ratio compared to men. The decrease in the average levels of these markers with age was significantly lower in women compared to men. Logistic regression was used to compute the odds ratio of CAD for a one standard deviation change in each lipid marker. Most notably, the apoB/apoA-1 ratio could be a strong risk factor for CAD, and increasing values of the ratio showed a curved line for the graph of the relationship between the ratio and risk. Conclusions: Our results confirmed that serum lipid levels in patients with CAD varied by age and gender. The apoB/apoA-1 ratio remains a strong risk factor for CAD.

Association Between Thyroid Dysfunction and Lipid Profiles Differs According to Age and Sex: Results from the Korean National Health and Nutrition Examination Survey

BACKGROUND

Lipid profiles of men and women change differently during the aging process. Guidelines recommend that dyslipidemia patients should consider screening for hypothyroidism without consideration of age or sex.

METHODS

Data from the sixth Korean National Health and Nutrition Examination Survey were used. A total of 4275 participants without thyroid disease and without a past history of dyslipidemia or dyslipidemia medication were evaluated. The association between thyroid dysfunction and lipid profiles (total cholesterol [TC], low-density lipoprotein cholesterol [LDLC], and triglycerides [TG]) was analyzed by age and sex.

RESULTS

The prevalence of thyroid dysfunction was significantly different according to TC and LDLC levels (p = 0.003 and p = 0.021, respectively). In women, the weighted prevalence of thyroid dysfunction was significantly different according to levels of TC, LDLC, and TG (p = 0.007, p = 0.016, and p = 0.044, respectively). However, in men, no association was found in any of the lipid profiles. Female participants were divided into two groups using a cutoff age of 55 years. In younger women, the weighted prevalence of thyroid dysfunction was different according to the levels of TC, LDLC, and TG (p = 0.013, p = 0.007, and p = 0.007, respectively). However, in older women, no association was found for any of the lipid profiles.

CONCLUSIONS

The prevalence of thyroid dysfunction was significantly different according to lipid profiles, and this association differed by age and sex.

Lower High-Density Lipoproteins Levels During Human Immunodeficiency Virus Type 1 Infection Are Associated With Increased Inflammatory Markers and Disease Progression

Introduction

High-density lipoproteins (HDL) are responsible for the efflux and transport of cholesterol from peripheral tissues to the liver. In addition, HDL can modulate various immunological mechanisms, including the inflammatory response. Inflammasomes are multiprotein complexes that have been reported to be activated during human immunodeficiency virus type 1 (HIV-1) infection, thus contributing to immune hyperactivation, which is the main pathogenic mechanism of HIV-1 progression. However, the relationship between HDL and inflammasomes in the context of HIV-1 infection is unclear. Therefore, this research aims to explore the association between HDL and the components of the inflammatory response during HIV-1 infection.

Methodology

A cross-sectional study, including 36 HIV-1-infected individuals without antiretroviral treatment and 36 healthy controls matched by sex and age, was conducted. Viral load, CD4+ T-cell counts, serum HDL, and C-reactive protein (CRP) were quantified. Serum cytokine levels, including IL-1β, IL-6, and IL-18, were assessed by ELISA. The inflammasome-related genes in peripheral blood mononuclear cells were determined by quantitative real-time PCR.

Results

HIV-1-infected individuals showed a significant decrease in HDL levels, particularly those subjects with higher viral load and lower CD4+ T-cell counts. Moreover, upregulation of inflammasome-related genes (NLRP3, AIM2, ASC, IL-1β, and IL-18) was observed, notably in those HIV-1-infected individuals with higher viral loads (above 5,000 copies/mL). Serum levels of IL-6 and CRP were also elevated in HIV-1-infected individuals. Significant negative correlations between HDL and the mRNA of NLRP3, AIM2, ASC, IL-1β, and IL-18, as well as viral load and CRP were observed in HIV-1-infected individuals. Likewise, a significant positive correlation between HDL and CD4+ T-cell counts was found.

Conclusion

In summary, our results indicate that HDL might modulate the expression of several key components of the inflammasomes during HIV-1 infection, suggesting a novel role of HDL in modifying the inflammatory state and consequently, the progression of HIV-1 infection.

C-reactive protein as an available biomarker determining mental component of health-related quality of life among individuals with spinal cord injury

OBJECTIVES

C-reactive protein (CRP) has been shown to correlate with health-related quality of life (HRQL) in some chronic medical conditions. However, these associations have not yet described in spinal cord injury (SCI). In this study, we tried to identify biomarkers associated with HRQL in SCI.

DESIGN

Cross-sectional.

SETTING

Tertiary rehabilitation center.

PARTICIPANTS

Referred patients to Brain and Spinal Cord Injury Research Center between November 2010 and April 2013.

OUTCOME MEASURE

Blood samples were taken to measure circulatory CRP, leptin, adiponectin, ferritin, parathyroid hormone, calcitonin, thyroid hormones, fasting plasma glucose and lipid profile. All the analyses were performed with adjustment for injury-related confounders (level of injury, injury completeness and time since injury) and demographic characteristics. HRQL was measured with Short Form health survey (SF-36).

RESULTS

The initial inverse association between CRP and total score of SF-36 (P: 0.006, r = -0.28) was lost after adjustment for confounders. However, the negative correlation between CRP and Mental Component Summary (MCS) remained significant (P: 0.0005, r = -0.38). Leptin level was inversely correlated with Physical Component Summary (PCS) (P: 0.02, r = -0.30).

CONCLUSION

Although CRP and leptin levels were not related with total scores of SF-36 questionnaire, CRP can be more useful in determining mental component of HRQL whereas leptin can be a determinant of physical component. The combined consideration of these two biomarkers may help to predict HRQL in individuals with SCI.

Effects of gender, age and menopausal status on serum apolipoprotein concentrations

OBJECTIVE

To undertake a comprehensive evaluation of apolipoprotein risk markers for cardiovascular disease (CVD) according to gender, age and menopausal status.

DESIGN

Cross-sectional analysis of independent associations of gender, age and menopause with serum apolipoproteins.

PARTICIPANTS

Apparently healthy Caucasian premenopausal (n = 109) and postmenopausal (n = 252) women not taking oral contraceptives or hormone replacement, and Caucasian men (n = 307).

MEASUREMENTS

Serum apolipoprotein (apo) B, A-I and A-II concentrations were measured, plus serum total cholesterol, low-density and high-density lipoprotein cholesterol (LDL-C and HDL-C, respectively), triglycerides, cholesterol in HDL subfractions and the apoB/apoA-I, LDL-C/apoB, HDL-C/apoA-I and HDL-C/apoA-II ratios. Analyses were undertaken with and without standardization for confounding characteristics and in 5-year age ranges.

RESULTS

Overall, apoB concentrations were highest in men but in women rose with age and menopause to converge, in the age range of 50-55 years, with concentrations in men. The LDL-C/apoB ratio was generally higher in women than in men. ApoA-I concentrations were highest in postmenopausal women and lowest in men (standardized median (IQR) 144 (130, 158) vs 119 (108, 132) g/l, respectively, P < 0·001). ApoA-II concentrations were also highest in postmenopausal women but were lowest in premenopausal women (40·3 (37·5, 44·5) vs 32·9 (30·5, 35·7) g/l, respectively, P < 0·001). Nevertheless, postmenopausal women had HDL-C/apoA-I and HDL-C/apoA-II ratios approaching the lowest ratios, which were seen in men.

CONCLUSIONS

Consistent with adverse effects on CVD risk, male gender, ageing in women and menopause were associated with increased apoB concentrations, and menopause and male gender were associated with a decreased cholesterol content of HDL particles.

Long working hours and overweight and obesity in working adults

Background

Previous studies have identified a link between gender and the various risk factors associated with obesity. We examined obesity risk factors in working adults to identify the effects of differences in body mass index (BMI) and percentage body fat (PBF) between women and men.

Methods

A total of 1,120 adults agreed to participate in the study. Data from 711 participants, including 411 women and 300 men, were analyzed. Multiple logistic regression analysis was used to estimate the effects of risk factors on obesity and being overweight. In addition, the least-squares (LS) means of both BMI and PBF were estimated by analysis of covariance (ANCOVA) in a generalized linear model. 

Results

Increases in BMI and PBF were significantly related to an age > 50 years and long working hours in women after compensating for confounding factors. Using the PBF criterion, the odds ratio (OR) of being overweight or obese in women > 50 years of age who worked for > 9 h a day was 3.9 (95% confidence interval [CI], 1.05–11.00). For BMI, women who were > 50 years of age and worked for > 9 h a day were 3.82 times (95% CI, 1.31–11.14) more likely to be overweight or obese than those who were < 50 years of age and worked for < 9 h a day.

Conclusion

Obesity in working adults was associated with > 50 years of age and long working hours in women. Further studies are needed to investigate the underlying mechanisms of this relationship and its potential implications for the prevention and management of excess weight and obesity.

Dyslipidemia and cardiovascular disease in women

Cardiovascular disease is the major cause of death in women in developed countries. Dyslipidemia is highly prevalent in women, particularly after the menopause. Elevated low-density lipoprotein cholesterol (LDL-C) has been identified as the key lipid parameter in both genders whereas HDL-cholesterol and triglycerides have been more closely associated, in some studies, with cardiovascular risk in women. Menopause has been shown to be associated with an increase in total and LDL-cholesterol and a decrease in HDL-cholesterol (predominantly in the HDL2 subfraction). Despite its beneficial effects on the lipid profile, hormone replacement therapy is not recommended for primary or secondary prevention of cardiovascular disease in women. The latest meta-analysis of statin trials with gender-specific outcomes showed a similar benefit in women and men. The addition of ezetimibe to simvastatin in patients with acute coronary syndromes showed a further reduction of the primary endpoint in both genders. While there are no gender-related differences in drug treatment of dyslipidemia, current guidelines, to avoid overtreatment, strongly suggest risk estimation before initiating lipid-lowering treatment in women without manifest cardiovascular disease.

Narrowing sex differences in lipoprotein cholesterol subclasses following mid-life: the very large database of lipids (VLDL-10B)

Background

Women have less risk of atherosclerotic cardiovascular disease compared with men up until midlife (ages 50 to 60), after which the gap begins to narrow post menopause. We hypothesized that the average lipid profile of women undergoes unfavorable changes compared with men after midlife.

Methods and Results

We examined lipids by sex and age in the Very Large Database of Lipids 10B (VLDL 10B) study. The analysis included 1 350 908 unique consecutive patients clinically referred for lipoprotein testing by density gradient ultracentrifugation from 2009 to 2011. Ratio variables were created for density subclasses of LDL‐C, HDL‐C, and VLDL‐C (LLDR, LHDR, LVDR, respectively). Men showed higher median LDL‐C values than women for ages 20 to 59, with the greatest difference in their 30s: 146 mg/dL in men versus 130 mg/dL in women. In contrast, women consistently had higher values after midlife (age 60), for example ages 70 to 79: 129 mg/dL in women versus 112 mg/dL in men. After age 50, women had higher LDL‐C each decade, for example 14% higher from their 30s to 50s, while HDL‐C concentrations did not differ. Women had more buoyant LDL‐C and HDL‐C (lower LLDR and LHDR) than men at all ages but the gap closed in higher age groups. In contrast, women had a generally denser VLDL‐C (higher LVDR) leading into midlife, with the gap progressively closing in higher age groups, approximating that of men in their 60s and 70s.

Conclusion

The narrowing sex differential in cardiovascular disease risk after midlife is mirrored by a higher total atherogenic lipoprotein cholesterol burden in women and a closer approximation of the less favorable density phenotype characteristic of men.

Lipids and lipoprotein ratios: contribution to carotid intima media thickness in adolescents and young adults with type 2 diabetes mellitus

BACKGROUND

Dyslipidemia is common among adolescents with type 2 diabetes (T2D).

OBJECTIVE

To assess whether the lipoprotein ratios of low-density lipoprotein (LDL) cholesterol/high-density lipoprotein (HDL) cholesterol or triglycerides/HDL or non-HDL cholesterol are more useful than the traditional lipid panel to predict increased arterial thickness in adolescents and young adults with T2D.

METHODS

We evaluated 244 adolescents and young adults with T2D in a cross-sectional study (mean age 18 years; 56% African American; 65% female). Demographics, anthropometrics, and laboratory data were collected. Arterial thickness was assessed with carotid intima media thickness (IMT). Bivariate correlations and general linear models were used to determine the independent contributions of the various lipid parameters to carotid IMT.

RESULTS

Bivariate correlations showed LDL/HDL ratio was the strongest predictor of carotid IMT (P < .02). After adjustment for potential covariates LDL/HDL was no longer significant. HDL cholesterol was the only lipid to independently (negatively) contribute to carotid IMT. Other risk factors that were independently associated with carotid IMT included age, race, sex, body mass index z score, and hemoglobin A1c. Together these cardiovascular risk factors explained <20% of the variance in carotid IMT.

CONCLUSIONS

HDL cholesterol is the only lipid to independently associate with carotid IMT. Lipoprotein ratios and non-HDL did not provide additional information. The low variance in carotid IMT explained by traditional risk factors suggests nontraditional risk factors may be important to assess to better understand the contributors to early-stage atherosclerosis in adolescents and young adults with T2D.

Pathological Importance of the Endothelin-1/ET(B) Receptor System on Vascular Diseases

Activation of the endothelin (ET)-1/ET receptor system is involved in the development of vascular diseases such as atherosclerosis, vascular hypertrophy, and restenosis. Some issues still remain unresolved including whether ET receptor antagonists are expected to become the new therapeutic tools for the treatment of vascular diseases. One of the unresolved critical points is the functional role of ET receptor subtypes on each vascular disease, in particular the pathophysiological roles of the ET_B receptor. We recently demonstrated that selective inhibition of the ET_B receptor system showed harmful effects in the development of neointimal formation after vascular injury. However, there was no apparent difference in the therapeutic effects between a nonselective ET_A/ET_B receptor antagonist and selective ET_A receptor antagonist. These findings indicate that antagonism of the ET_A receptor system is essential for suppressing vascular remodeling, irrespective of the presence of ET_B-receptor-mediated actions, although the selective ET_B receptor antagonist worsens vascular remodeling. In addition, we found that ET receptor systems contribute to sex differences in the severity of vascular disease, thereby suggesting that the efficacy of ET receptor antagonists for vascular diseases may differ between sexes. In this paper, we outline the roles of the ET-1/ET_B receptor system on vascular diseases and its sex differences.

Pathophysiological roles of endothelin receptors in cardiovascular diseases

Endothelin (ET)-1 derived from endothelial cells has a much more important role in cardiovascular system regulation than the ET-2 and ET-3 isoforms. Numerous lines of evidence indicate that ET-1 possesses a number of biological activities leading to cardiovascular diseases (CVD) including hypertension and atherosclerosis. Physiological and pathophysiological responses to ET-1 in various tissues are mediated by interactions with ET(A)- and ET(B)-receptor subtypes. Both subtypes on vascular smooth muscle cells mediate vasoconstriction, whereas the ET(B)-receptor subtype on endothelial cells contributes to vasodilatation and ET-1 clearance. Although selective ET(A)- or nonselective ET(A)/ET(B)-receptor antagonisms have been assumed as potential strategies for the treatment of several CVD based on clinical and animal experiments, it remains unclear which antagonisms are suitable for individuals with CVD because upregulation of the nitric oxide system via the ET(B) receptor is responsible for vasoprotective effects such as vasodilatation and anti-cell proliferation. In this review, we have summarized the current understanding regarding the role of ET receptors, especially the ET(B) receptor, in CVD.

Prospective association of low total testosterone concentrations with an adverse lipid profile and increased incident dyslipidemia

BACKGROUND

Earlier studies have suggested that total testosterone concentrations influence the lipid metabolism. Whether these concentrations are prospectively associated with an adverse lipid profile and an increased risk of incident dyslipidemia has not yet been investigated.

METHODS AND RESULTS

Our study population consisted of 1468 men, aged 20–79 years, who were repeatedly examined as part of the population-based Study of Health in Pomerania. Serum total testosterone concentrations measured by the chemiluminescent enzyme immunoassays were categorized into age-specific quartiles. We used generalized estimating equations models to assess the prospective association between total testosterone concentrations and lipid profile components including total cholesterol (TC), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride (TG) concentrations, as well as incident dyslipidemia after 5 years of follow-up. Multivariate models revealed that total testosterone concentrations in the lowest quartile were associated with higher TC and TG concentrations in both cross-sectional [TC: 0.23 mmol/l (95% confidence interval, CI, 0.02–0.42); TG: 0.73 mmol/l (95% CI, 0.53–0.94)] and longitudinal analyses [TC: 0.20 mmol/l (95% CI, 0.03–0.27); TG: 0.62 mmol/l (95% CI, 0.43–0.80)], but not with high-density lipoprotein cholesterol or low-density lipoprotein cholesterol concentrations. Baseline prevalence of dyslipidemia was 57.1% with a crude incidence rate of 46.6 per 1000 person-years. Total testosterone concentrations in the lowest quartile predicted dyslipidemia; age-adjusted relative risks (RR) for men in quartiles 1, 2, and 3 as compared to quartile 4 (highest, reference) were 1.28 (95% CI, 1.06–1.54), 1.10 (95% CI, 0.91–1.33), and 1.05 (95% CI, 0.86–1.29), respectively. This effect was particularly strong among men aged 20–39 years (relative risk, 1.51; 95% CI, 1.08–2.10).

CONCLUSION

Low total testosterone concentrations are prospectively associated with an adverse lipid profile and increased risk of incident dyslipidemia. These findings are particularly interesting and may contribute to an explanation for the higher cardiovascular disease risk in men with lower total testosterone concentrations.

Testosterone and the aging male: to treat or not to treat?

It is well-established that total testosterone (TT) in men decreases with age and that bioavailable testosterone (bio-T) falls to an even greater extent. The clinical relevance of declining androgens in the aging male and use of testosterone replacement therapy (TRT) in this situation is controversial. Most studies have been short term and there are no large randomized placebo-controlled trials. Testosterone has many physiological actions in: muscles, bones, hematopoietic system, brain, reproductive and sexual organs, adipose tissue. Within these areas it stimulates: muscle growth and maintenance, bone development while inhibiting bone resorption, the production of red blood cells to increase hemoglobin, libido, enhanced mood and cognition, erectile function and lipolysis. Anabolic deficits in aging men can induce: frailty, sarcopenia, poor muscle quality, muscle weakness, hypertrophy of adipose tissue and impaired neurotransmission. The aging male with reduced testosterone availability may present with a wide variety of symptoms which in addition to frailty and weakness include: fatigue, decreased energy, decreased motivation, cognitive impairment, decreased self-confidence, depression, irritability, osteoporotic pain and the lethargy of anemia. In addition, testosterone deficiency is also associated with type-2 diabetes, the metabolic syndrome, coronary artery disease, stroke and transient ischemic attacks, and cardiovascular disease in general. Furthermore, there are early studies to suggest that TRT in men with low testosterone levels may improve metabolic status by: lowering blood sugar and HbA1C in men with type-2 diabetes, reducing abdominal girth, ameliorating features of the metabolic syndrome, all of which may be protective of the cardiovascular system. The major safety issue is prostate cancer but there is no evidence that supports the idea that testosterone causes the development of a de novo cancer. So on balance in a man with symptoms of hygonadism and low or lowish levels of testosterone with no evidence of prostate cancer such as a normal PSA a therapeutic (4-6 months) trial of TRT is justified. Treatment and monitoring of this duration will determine whether the patient is responsive.

Increased C-reactive protein levels in overweight and obese women taking exogenous hormones: the United Kingdom Women's Heart Study (UKWHS)

OBJECTIVE

Women's cardiovascular risk factors, including inflammatory markers such as C-reactive protein (CRP) which is emerging as a major association with cardiovascular disease (CVD) risk, can be influenced by the oral contraceptive (OC) pill in premenopausal and hormone replacement (HR) in postmenopausal women and by central adiposity which is associated with a heightened inflammatory state. The interaction between central obesity and different hormone use in both pre and postmenopausal women has not previously been reported in a study spanning the whole age range associated with hormone use.

DESIGN

Observational, cross-sectional study.

PATIENTS

Only healthy women were included in this study.

MEASUREMENTS

A total of 21,310 women aged 30-64 employed by Marks & Spencer participated. They completed a health questionnaire and were screened for CVD risk factors including blood pressure, weight, height, waist and hip circumference, lipids and lipoproteins, CRP and fibrinogen.

RESULTS

Compared with non-users, women who took the OC or HR had significantly higher CRP levels. This was more marked than effects on other CVD risk factors. It was further compounded by the independent effect of increased waist circumference. The CRP increase was greatest (more than twice that of nonhormone users) in premenopausal women with the highest quartile of waist circumference who took the combined contraceptive pill.

CONCLUSIONS

Women who received first the combined OC and then HR may be exposed over much of their life to high CRP levels aggravated by central obesity. The health consequences of this require further investigation.

Gender differences in insulin resistance, body composition, and energy balance

BACKGROUND

Men and women differ substantially in regard to degrees of insulin resistance, body composition, and energy balance. Adipose tissue distribution, in particular the presence of elevated visceral and hepatic adiposity, plays a central role in the development of insulin resistance and obesity-related complications.

OBJECTIVE

This review summarizes published data on gender differences in insulin resistance, body composition, and energy balance, to provide insight into novel gender-specific avenues of research as well as gender-tailored treatments of insulin resistance, visceral adiposity, and obesity.

METHODS

English-language articles were identified from searches of the PubMed database through November 2008, and by reviewing the references cited in these reports. Searches included combinations of the following terms: gender, sex, insulin resistance, body composition, energy balance, and hepatic adipose tissue.

RESULTS

For a given body mass index, men were reported to have more lean mass, women to have higher adiposity. Men were also found to have more visceral and hepatic adipose tissue, whereas women had more peripheral or subcutaneous adipose tissue. These differences, as well as differences in sex hormones and adipokines, may contribute to a more insulin-sensitive environment in women than in men. When normalized to kilograms of lean body mass, men and women had similar resting energy expenditure, but physical energy expenditure was more closely related to percent body fat in men than in women.

CONCLUSION

Greater amounts of visceral and hepatic adipose tissue, in conjunction with the lack of a possible protective effect of estrogen, may be related to higher insulin resistance in men compared with women.

Gender-specific differences in the kinetics of nonfasting TRL, IDL, and LDL apolipoprotein B-100 in men and premenopausal women

OBJECTIVE

To investigate mechanisms underlying gender differences in serum lipoprotein concentrations, the kinetic behavior of apoB-100 was assessed.

METHODS AND RESULTS

Twenty subjects (<50 years; 12 men and 8 premenopausal women) were provided a Western diet for 4 to 6 weeks, after which the kinetics of apoB-100 in triglyceride-rich, intermediate-density, and low-density lipoprotein (TRL, IDL, and LDL) were determined in the fed state. Nonfasting plasma TC, LDL-C, and triglyceride concentrations were 23%, 34%, and 57% lower, respectively, in the women compared with men. Plasma TRL and LDL apoB 100 pool sizes were lower by 40% and 30%, respectively. These differences were accounted for by higher TRL and LDL apoB 100 fractional catabolic rates (FCR), rather than differences in production rates (PR). Plasma TRL-C and LDL-C were positively correlated with TRL and LDL apoB 100 concentrations and pool size, and negatively correlated with TRL and LDL apoB 100 FCR (women: r=-0.59, P<0.01 and r=-0.54, P<0.04, and men: r=-0.43, P<0.05 and r=-0.44, P<0.05). No significant associations were observed between plasma TRL-C and LDL-C and PR.

CONCLUSIONS

These data suggest the mechanism for lower TRL-C and LDL-C concentrations in women was determined predominantly by higher TRL and LDL FCR rather than lower PR. This could explain, in part, the lower CVD risk in premenopausal women relative to men.

Postprandial triglyceride metabolism in elderly men with subnormal testosterone levels

AIM

To investigate the level of postprandial triglycerides (TG)s in elderly men with subnormal testosterone level (< or = 11.0 nmol/L) compared to men with normal testosterone level (> 11.0 nmol/L).

METHODS

Thirty-seven men with subnormal and 41 men with normal testosterone aged 60-80 years underwent an oral fat load and TG levels were measured fasting and 2, 4, 6 and 8 h afterwards.

RESULTS

Men with subnormal testosterone had significantly higher body mass index (BMI) and waist circumference (P < 0.001) than men with normal testosterone. They had significantly higher area under curve (AUC, P = 0.037), incremental area under curve (AUCi, P = 0.035) and TG response (TGR, P = 0.014) for serum-TG and significantly higher AUC (P = 0.023), AUCi (P = 0.023) and TGR (P = 0.014) for chylomicron-TG compared to men with normal testosterone level. Adjusting for waist circumference erased the significant differences between the groups in postprandial triglyceridemia.

CONCLUSION

Men with subnormal testosterone have increased postprandial TG levels indicating an impaired metabolism of postprandial TG-rich lipoproteins (TRL), which may add to an unfavourable lipid profile and promote development of atherosclerosis.

Associations of usual sleep duration with serum lipid and lipoprotein levels

STUDY OBJECTIVES

We examined the individual association between sleep duration and a high serum triglyceride, low HDL cholesterol, or high LDL cholesterol level.

DESIGN AND SETTING

The present study analyzed data from the National Health and Nutrition Survey that was conducted in November 2003 by the Japanese Ministry of Health, Labour and Welfare. This survey was conducted on residents in the districts selected randomly from all over Japan.

PARTICIPANTS

The subjects included in the statistical analysis were 1,666 men and 2,329 women aged 20 years or older.

INTERVENTION

N/A.

MEASUREMENTS AND RESULTS

Among women, both short and long sleep durations are associated with a high serum triglyceride level or a low HDL cholesterol level. Compared with women sleeping 6 to 7 h, the relative risk of a high triglyceride level among women sleeping <5 h was 1.51 (95% CI, 0.96-2.35), and among women sleeping > or =8 h was 1.45 (95% CI, 1.00-2.11); the relative risk of a low HDL cholesterol level among women sleeping <5 h was 5.85 (95% CI, 2.29-14.94), and among women sleeping > or =8 h was 4.27 (95% CI, 1.88-9.72). On the other hand, it was observed that the risk of a high LDL cholesterol level was lower among men sleeping > or =8 h. These analyses were adjusted for the following items: age, blood pressure, body mass index, plasma glucose level, smoking habit, alcohol consumption, dietary habits, psychological stress, and taking cholesterol-lowering medications.

CONCLUSIONS

Usual sleep duration is closely associated with serum lipid and lipoprotein levels.

Influence of Aging and Menopause on Lipids and Lipoproteins in Women

The actions of endogenous estrogens on the cardiovascular system can be mediated directly on the vessels or indirectly through the modulation of cardiovascular risk factors. Aging and menopause are the main causes that lead to an adverse lipid profile in women. The influence of age on prevalence of increased plasma triglyceride levels and on larger variation in fasting triglyceride levels has been reported in both genders. However, the increased prevalence of increased cholesterol with age was only found in women. The high-density lipid cholesterol level is higher in women than in men throughout all ages. Obesity may also exaggerate the unfavorable lipid profile in aging and/or menopausal women. In the last decades the management of the menopausal women has been a subject of concern for medical scientific groups. In this review, the current understanding of an influence of age and menopause on lipids and lipoproteins concentration in women will be analyzed.

Lifestyle and the Risk of Cardiovascular Disease in Women: Is Physical Activity an Equal Opportunity Benefactor?

Cardiovascular disease is the number one killer of women in the United States. It is estimated that 36.6% of women older than age 20 have some form of cardiovascular disease. In 2004, an estimated 459 100 women died from cardiovascular disease, more than 10 times the number of women who died from breast cancer that same year. Regular physical activity of moderate intensity, such as brisk walking, reduces the risk of cardiovascular disease and mortality in women. The benefits of more vigorous exercise are not clear, but the apparent lack of a dose-response relationship between exercise intensity and cardiovascular benefit may be the result of the design of many epidemiologic and interventional studies. Studies examining the benefits of greater cardiorespiratory fitness for women are limited, but the data suggest that they are similar to that of men. Women may require greater caloric expenditure than men for weight reduction, but this issue may be confounded by other variables such as caloric intake and spontaneous physical activity. The risk of cardiovascular disease associated with type 2 diabetes is much greater in women than in men. Regular physical activity and greater cardiorespiratory fitness are associated with a lower incidence and prevalence of type 2 diabetes in women. Greater cardiorespiratory fitness has also been found to be protective of the metabolic syndrome, but the benefit of physical activity is unclear. Limited evidence suggests that moderate-intensity activities can lower systolic blood pressure in women. There is a pressing need for more research into the health benefits of regular physical activity in women.

Low serum testosterone in men is inversely associated with non-fasting serum triglycerides: the Tromsø study

OBJECTIVE

To study the relationships between endogenous testosterone, sex hormone-binding globulin (SHBG) and serum lipids in non-fasting men.

METHODS

We performed a cross-sectional study in 1274 men without known cardiovascular disease who participated in a population-based study, the 1994/1995 Tromsø study. Anthropometric characteristics were measured and questionnaires regarding lifestyle and medical history were completed. Non-fasting blood samples were drawn between 08.00 and 16.00h, and total testosterone, SHBG, triglycerides (TG), total cholesterol (TC) and high-density lipoprotein (HDL) were analyzed.

RESULTS

In stratified analyses based on sampling time, a linear increase in serum TG levels was found in men with total testosterone levels below the 50th percentile during the day (p for trend=0.004). In contrast, serum triglycerides did not change during the day in men with testosterone levels above the 50th percentile. In regression analyses, total testosterone and SHBG were inversely and independently associated with TG (p<0.001 and p<0.001 respectively), and positively and independently associated with HDL (p=0.005 and p<0.001, respectively). Men with an unfavorable lipid profile (HDL <0.90 and TG >1.8) had significantly lower levels of total testosterone and SHBG (p=0.004 and p<0.001, respectively) in age and BMI adjusted analyses, compared to men with a normal lipid profile.

CONCLUSIONS

Low serum total testosterone was associated with a linear increase in serum TG during the day, and was independently associated with an unfavorable lipid profile. Our findings may indicate that low total testosterone is associated with impaired TG metabolism in men.

Fasting serum triglyceride and high-density lipoprotein cholesterol levels in patients intended to be treated for dyslipidemia

Objective

The aim of the present investigation was to evaluate the influence of serum triglycerides (TG) on other plasma lipids in patients to be treated for dyslipidemia.

Methodology

Lipid profiles of a cohort of 801 patients (487 males and 314 females) aged 57 ± 9 years (mean ± SD) were evaluated. Patients were stratified according to their plasma lipid levels. They were divided into various groups on the basis of serum TG (≥150 or <150 mg/dL) and high-density lipoprotein cholesterol (HDL-C) (≥40 or <40 mg/dL).

Results

Patients with TG ≥ 150 mg/dL had a higher total cholesterol and lower HDL-C levels compared with those with TG < 150 mg/dL, (p < 0.001). Patients with HDL-C < 40 mg/dL had a lower serum total cholesterol and higher TG compared with those with HDL-C ≥ 40 mg/dL (p = 0.011 and p < 0.0001, respectively). In all patients as well as in the subgroups, an inverse correlation between TG and HDL-C was found (r = −0.377, p < 0.001).

Conclusions

Although, the metabolic pathway for TG and HDL-C is closely linked, an inverse correlation between TG and HDL-C levels seems to exist in the entire sampled population. This correlation also appears to persist in fasting patients with low levels of TG.

Metabolic syndrome and gender differences in postprandial lipaemia

BACKGROUND

Postprandial hyperlipidaemia may be a predictor of vascular risk.

DESIGN

We evaluated postprandial lipaemia after an oral fat tolerance test (OFTT) in men (n=41) and women (n=21) with metabolic syndrome (MetS).

METHODS

Triglyceride (TG) levels were measured before and 2, 4, 6 and 8 h after the fat load.

RESULTS

Men showed a greater plasma TG response 8 h after the fat load (284+/-117 versus 224+/-126 mg/dl, P=0.029). Only fasting TG levels significantly predicted the TG area under the curve (AUC) and incremental AUC.

CONCLUSIONS

Men had a more pronounced postprandial hypertriglyceridaemia and seem to have delayed TG clearance.

Effect of estradiol 17beta upon coronary artery vasoconstrictor response to methylergometrine maleate in female menopausal patients

BACKGROUND

Estrogens produce several beneficial effects upon the cardiovascular system. Amongst these, an endothelium-independent effect has been convincingly demonstrated only in vitro, while there is no evidence for such an effect in vivo. The aim of the present study was to evaluate the effect of acute administration of estradiol 17beta upon coronary artery reactivity to methylergometrine in 16 menopausal patients with coronary artery disease.

METHODS

Sixteen menopausal patients underwent coronary angiography at rest and after incremental doses of methylergometrine (intracoronary 2, 10, 30 microg) before and 20 min after either intracoronary estradiol 17beta (20 ng/mL at 1 mL/min for 20 min; 8 patients) or placebo (Dextrose 5%, 1 mL/min; 8 patients).

RESULTS AND CONCLUSIONS

No significant differences were observed in baseline coronary artery diameter or area between the 2 groups. No significant differences in the degree of coronary artery constriction were observed after either estradiol 17beta or placebo at submaximal doses of methylergometrine. However, the degree of coronary artery constriction after maximal doses of methylergometrine was significantly attenuated by estradiol 17beta compared to placebo (change in diameter: -0.9+/-4.5% vs. -19+/-6%, p<0.001; change in area: -3.2+/-9% vs. -32.2+/-10%, p<0.001). Estradiol 17beta reduces coronary artery constriction following methylergometrine administration in menopausal patients with coronary artery disease. This effect may be related to the calcium-antagonist properties of the ovarian hormone.

High-density lipoprotein subfractions in normolipidemic individuals without clinical atherosclerosis lipoprotein subfractions in an adult population

This study evaluated the serum concentrations of lipids, lipoproteins, apolipoproteins, and high-density lipoprotein (HDL) subfractions in Brazilian adults. We analyzed the distribution of lipids in HDL2 and HDL3 in a normolipidemic population without evidence of established cardiovascular disease (CVD). A total of 93 males and 92 females, healthy and normolipidemic, volunteered to be submitted to a clinical examination, a blood collection, and to answer a questionnaire aimed at determining signs and symptoms of atherosclerotic disease. Their fasting plasma lipid, lipoproteins, apolipoproteins, and the cholesterol and triglyceride concentrations in HDL2 and HDL3, isolated by microultracentrifugation, were determined by enzymatic-colorimetric methods. The interpercentile intervals (2.5-97.5) for the population were established as being 5-18 mg/dL in men and 4-28 mg/dL in women for HDL2 cholesterol (HDL2chol) and 1-57 mg/dL in men and 2-61 mg/dL in women for HDL3 cholesterol (HDL3chol). HDL2 triglyceride levels (HDL2Tg) in men were 1-26 mg/dL and in women 2-28 mg/dL; moreover, the HDL3 triglyceride (HDL3Tg) intervals were established as 4-46 mg/dL for both sexes. The determination of reference ranges for lipids in HDL subfractions in populations without clinical atherosclerosis, is an useful tool for metabolic, diagnostic, and therapeutic approaches. We determined the intervals for HDL2chol, HDL3chol, HDL2Tg, and HDL3Tg. There were variations with sex and/or age for HDL2chol, HDL3chol, and HDL2Tg in the studied population.

Age-related anthropometric remodelling resulting in increased and redistributed adiposity is associated with increases in the prevalence of cardiovascular risk factors in Chinese subjects

BACKGROUND

Ageing promotes increases in the prevalence of components of the metabolic syndrome, which obesity often underlies.

METHODS

We report the relationship between ageing, obesity and other cardiovascular risk factors in 694 community-based Chinese subjects in gender-specific groups of three age ranges: 20.0-39.9 (young), 40.0-59.9 (middle-aged) and 60.0-79.9 (old-aged) years.

RESULTS

Body mass index (BMI) values were similar in males in each age group, but waist and percentage body fat increased (6.6, and 39.5%, both p < 0.001, respectively), from young to old-age groups, as did blood pressure and glycated haemoglobin levels (all p < 0.001). In the females, increases (all p < 0.001) in percentage body fat (29.3%) were accompanied by greater increases in BMI (10.3%) and waist (19.2%) than the males. Blood pressure, glycated haemoglobin, total and LDL-cholesterol and triglyceride levels increased linearly with age (all p < 0.001).

CONCLUSION

Age-related increases in central adiposity and percentage body fat were associated with increasingly adverse cardiovascular risk factor profiles.

Estrogen prevents cardiomyocyte apoptosis through inhibition of reactive oxygen species and differential regulation of p38 kinase isoforms

From human and animal studies, estrogen is known to protect the myocardium from an ischemic insult. However, there is limited knowledge regarding mechanisms by which estrogen directly protects cardiomyocytes. In this report, we employed an in vitro model, in which cultured rat cardiomyocytes underwent prolonged hypoxia followed by reoxygenation (H/R), to study the cardioprotective mechanism of estrogen. 17-beta-estradiol (E2) acting via estrogen receptors inhibited H/R-induced apoptosis of cardiomyocytes. Mitochondrial reactive oxygen species (ROS) generated from H/R activated p38alpha MAPK, and inhibition of p38alpha with SB203580 significantly prevented H/R-induced cell death. E2 suppressed ROS formation and p38alpha activation by H/R and concomitantly augmented the activity of p38beta. Unlike p38alpha, p38beta was little affected by H/R. Dominant negative p38beta protein expression decreased E2-mediated cardiomyocyte survival and ROS suppression during H/R stress. The prosurvival signaling molecule, phosphoinositol-3 kinase (PI3K), has previously been linked to cell survival following ischemia-reperfusion injury. Here, E2-activated PI3K was found to inhibit ROS generated from H/R injury, leading to inhibition of downstream p38alpha. We further linked these signaling pathways in that p38beta was activated by E2 stimulation of PI3K. Thus, E2 differentially modulated two major isoforms of p38, leading to cardiomyocyte survival. This was achieved by signaling through PI3K, integrating cell survival mediators.

Perspectives on Dyslipidemia and Coronary Heart Disease in Women

Coronary heart disease (CHD) remains the leading cause of death among American women. Numerous differences exist between younger and older women and between women and men with respect to the pathology of CHD and its incidence and prevalence over the life cycle. Differences in lipoprotein levels and lipid fractions play an important role in CHD risk. Hormonal influences on lipoprotein levels in women are complex, change throughout the life span, and are influenced by the administration of oral contraceptives and hormone replacement therapy. Women with obesity, metabolic syndrome, or diabetes have lipid profiles that adversely affect CHD risk. To date, no randomized trials testing the impact of lifestyle changes on lipoprotein levels and subsequent CHD events in non-institutionalized women have been performed, and women have not been well represented in clinical end point trials of pharmacologic lipid-lowering therapy. Available evidence suggests that lipid-lowering therapy with statins does provide benefit in reducing the risk of coronary events in women; however, women remain undertreated, and more data are needed to determine optimal cardiovascular prevention and treatment in this population.

Sex-dependent variables in the modulation of postalimentary lipemia

OBJECTIVE

To quantify in young adults the sex-dependent differences in lipemic responses to a fat meal, we measured the association of these responses with markers of atherosclerosis and determined their metabolic regulators.

METHODS

Forty-nine normolipidemic volunteers, 25 women and 24 men, were matched according to age, body mass index, waist circumference, diet, physical activity, and apolipoprotein-E phenotyping. After receiving a standardized fat meal (40 g of fat/m2 of body surface area), serial blood samples were drawn for laboratory analysis. Common carotid intima-media thickness was measured.

RESULTS

The lipemic responses were much greater in men than in women for plasma triacylglycerol (TAG), cholesterol, and TAG in TAG-rich lipoproteins, non-esterified fatty acids, phospholipids, and apolipoprotein-B100. Men presented with increased blood pressure, carotid intima-media thickness, TAG, hepatic lipase, and insulin and lower high-density lipoprotein cholesterol, apolipoprotein-AI, and non-esterified fatty acid concentrations. Only in men did carotid intima-media thickness correlate marginally with titers of autoantibodies to epitopes of oxidized low-density lipoprotein; in addition, phospholipids and cholesteryl esters were negatively related to autoantibodies. Multivariate analysis indicated that age (R2 = 45%), waist circumference (R2 = 19%), phospholipids (R2 = 39%), non-esterified fatty acids (R2 = 29%), insulin (R2 = 17%), lipoprotein lipase activity (R2 = 16%), and cholesteryl ester transfer protein (an exploratory variable; R2 = 6%) are strong determinants of postalimentary lipemia in women and that only insulin (R2 = 55%) and phospholipids (R2 = 37%) are determinants in men.

CONCLUSIONS

We have provided data explaining that postalimentary lipemia is differently regulated by sex. Several risk factors for coronary heart disease and significant associations with atherosclerosis biomarkers were found only in men.