Smallest LDL particles are most strongly related to coronary disease progression in men

Coronary artery calcification and high-volume physical activity: role of lower intensity vs. longer duration of exercise

AIMS

While high-volume physical activity (PA) has been linked to elevated coronary artery calcification (CAC), the role of intensity vs. duration of PA has not been investigated. The purpose of the study was to examine the role of intensity vs. duration of PA in relation to CAC.

METHODS AND RESULTS

Data are from 23 383 apparently healthy men who completed a PA questionnaire and underwent CAC scanning as part of a preventive examination. Self-reported PA was categorized into four groups of average intensity and weekly duration of PA [average intensity: 1, 3-5.9, 6-8.9, and 9-12 metabolic equivalents of task (METs); weekly duration: 0, > 0-<2, 2-<5, and ≥5 h/week]. Mean CAC and CAC ≥ 100 Agatston units (AU) were regressed separately on continuous or categorical average intensity and weekly duration of PA. The mean (standard deviation) age was 51.7 (8.3) years, and mean CAC was 174.8 (543.6) AU with 23.5% of men presenting with CAC ≥ 100 AU. Higher average intensity of PA was related to lower mean CAC [-3.1%/MET, 95% confidence interval (CI): -4.6, -1.6%/MET] and lower relative risk (RR) of CAC ≥ 100 AU (RR: 0.99, 95% CI: 0.98, 1.00/MET). Opposite trend was observed for the duration component wherein higher weekly duration of PA was significantly associated with greater mean CAC and RR of CAC ≥ 100 AU.

CONCLUSION

Elevated CAC was associated with lower average intensity and longer duration of PA in men, providing new insight into the complex relationship between leisure-time PA behaviours and risk of CAC.

Small Dense LDL: Scientific Background, Clinical Relevance, and Recent Evidence Still a Risk Even with 'Normal' LDL-C Levels

Residual cardiovascular disease event risk, following statin use and low-density lipoprotein cholesterol (LDL-C) reduction, remains an important and common medical conundrum. Identifying patients with significant residual risk, despite statin drug use, is an unmet clinical need. One pathophysiologic disorder that contributes to residual risk is abnormal distribution in lipoprotein size and density, which is referred to as lipoprotein heterogeneity. Differences in low density lipoprotein (LDL) composition and size have been linked to coronary heart disease (CHD) risk and arteriographic disease progression. The clinical relevance has been investigated in numerous trials since the 1950s. Despite this long history, controversy remains regarding the clinical utility of LDL heterogeneity measurement. Recent clinical trial evidence reinforces the relevance of LDL heterogeneity measurement and the impact on CHD risk prediction and outcomes. The determination of LDL subclass distribution improves CHD risk prediction and guides appropriate treatment.

The effects of fat consumption on low-density lipoprotein particle size in healthy individuals: a narrative review

Cardiovascular disease (CVD) is the number one contributor to death in the United States and worldwide. A risk factor for CVD is high serum low-density lipoprotein cholesterol (LDL-C) concentrations; however, LDL particles exist in a variety of sizes that may differentially affect the progression of CVD. The small, dense LDL particles, compared to the large, buoyant LDL subclass, are considered to be more atherogenic. It has been suggested that replacing saturated fatty acids with monounsaturated and polyunsaturated fatty acids decreases the risk for CVD. However, certain studies are not in agreement with this recommendation, as saturated fatty acid intake did not increase the risk for CVD, cardiovascular events, and/or mortality. Furthermore, consumption of saturated fat has been demonstrated to increase large, buoyant LDL particles, which may explain, in part, for the differing outcomes regarding fat consumption on CVD risk. Therefore, the objective was to review intervention trials that explored the effects of fat consumption on LDL particle size in healthy individuals. PubMed and Web of Science were utilized during the search process for journal articles. The results of this review provided evidence that fat consumption increases large, buoyant LDL and/or decreases small, dense LDL particles, and therefore, influences CVD risk.

Apolipoprotein Mimetic Peptides: An Emerging Therapy against Diabetic Inflammation and Dyslipidemia

Obesity has achieved epidemic status in the United States, resulting in an increase in type 2 diabetes mellitus, dyslipidemia, and cardiovascular disease. Numerous studies have shown that inflammation plays a key role in the development of insulin resistance and diabetic complications. HDL cholesterol levels are inversely associated with coronary heart disease in humans. The beneficial effect of HDL is due, in part, to apolipoproteins A-I and E, which possess anti-inflammatory properties. The functional quality of HDL, however, may be reduced in the context of diabetes. Thus, raising levels of functional HDL is an important target for reducing inflammation and diabetic complications. Apo A-I possesses eight alpha-helical sequences, most of which form class A amphipathic helical structures. Peptides belonging to this class inhibit atherogenesis in several mouse models. Additional peptides based on structural components of apoE have been shown to mediate a rapid clearance of atherogenic lipoproteins in dyslipidemic mice. In this review, we discuss the efficacy of apolipoprotein mimetic peptides in improving lipoprotein function, reducing inflammation, and reversing insulin resistance and cardiometabolic disease processes in diabetic animals.

Differences Between Morbid Obesity With Metabolic Syndrome and Overweight Turkish Adult Participants in Multiple Atherosclerotic Cardiovascular Disease Risk Factors

Obesity and metabolic syndrome (MetS) are public health problems and are increasing globally. We assessed the differences in lipid profiles through lipid testing, thrombotic and inflammatory parameters, and oxidative stress indexes between overweight and obese patients with MetS in a Turkish adult population. We included 100 obese (body mass index [BMI] >30 kg/m²) patients with MetS (66 women, 34 men, mean age 54.0 ± 10.1 years) and 15 overweight (BMI 25-30 kg/m²) individuals (11 women, 4 men, mean age 50.2 ± 14.5 years) as controls. The group with MetS had significantly higher levels of glycaemia, uric acid, high-sensitivity C-reactive protein, homocysteine, fibrinogen, total cholesterol, low-density lipoprotein cholesterol (LDL-C), triglycerides, small dense LDL, oxidized LDL, apolipoprotein B (Apo B), lipoprotein (a), small and intermediate high-density lipoprotein (HDL) particles, oxidative stress index, and significantly lower levels of HDL-cholesterol (HDL-C), Apo A, and large HDL particles. In conclusion, obesity with MetS increase atherogenic dyslipidemia and thrombotic, inflammatory and oxidative stress biomarkers. Furthermore, obesity with MetS decreases protective mechanisms of atherosclerosis. We should at least try to prevent overweight individuals from becoming obese with MetS.

Transport of LDLs into the arterial wall: impact in atherosclerosis

PURPOSE OF REVIEW

Atherosclerosis is a complicated cardiovascular disease characterized by unbalanced lipid metabolism and unresolved inflammation that occurred inside of arteries. The transcytosis of LDL across the endothelium and its accumulation in the arterial wall is the initial step of atherosclerosis. Here, we summarize recent research into the understanding of the regulatory mechanisms of endothelial LDL transcytosis and its relevance in the development of atherosclerosis.

RECENT FINDINGS

A number of recent studies have revealed the contribution of caveolae, activin-like kinase 1 (ALK1) or scavenger receptor B1 (SR-B1) in endothelial LDL transcytosis and the progression of atherosclerosis. Caveolin-1 (Cav-1), the major protein component in caveolae, is required for the formation of caveolae and caveolae-mediated LDL uptake and transcytosis across the endothelium. SR-B1 and ALK1 directly bind LDL and facilitate the transport of LDL through the endothelial cells. The change in expression of caveolae-associated proteins and SR-B1 regulates endothelial LDL transcytosis and the pathogenesis of atherosclerosis.

SUMMARY

Caveolae, ALK1 and SR-B1 are identified as key regulators in the LDL transcytosis across the endothelium. Endothelial LDL transcytosis might be a potential therapeutic approach to limit the initiation of early atherosclerosis and treat the atherosclerotic vascular diseases.

Plasma extracellular vesicle proteins are associated with stress-induced myocardial ischemia in women presenting with chest pain

Diagnosing stable ischemic heart disease (IHD) is challenging, especially in females. Currently, no blood test is available. Plasma extracellular vesicles (EV) are emerging as potential biomarker source. We therefore aimed to identify stress induced ischemia due to stable IHD with plasma extracellular vesicle protein levels in chest pain patients. We analyzed 450 patients suspected for stable IHD who were referred for ⁸²Rb PET/CT in the outpatient clinic. Blood samples were collected before PET/CT and plasma EVs were isolated in 3 plasma subfractions named: TEX, HDL, LDL. In total 6 proteins were quantified in each of these subfractions using immuno-bead assays. CD14 and CystatinC protein levels were independent significant predictors of stress-induced ischemia in the LDL and the HDL subfraction and SerpinC1 and SerpinG1 protein levels in the HDL fraction. Subgroup-analysis on sex revealed that these associations were completely attributed to the associations in women. None of the significant EV proteins remained significant in men. Plasma EV proteins levels are associated with the presence of stable IHD in females presenting with chest pain. This finding, if confirmed in larger cohort studies could be a crucial step in improving diagnostic assessment of women with suspected IHD.

Coronary Artery Disease is More Severe in Patients with Non-Alcoholic Steatohepatitis than Fatty Liver

Non-alcoholic fatty liver disease (NAFLD) is associated with a higher risk of atherosclerotic disease. However, the relationships between the severity of coronary atherosclerosis and pathologic findings in patients with NAFLD remain unknown. We aimed to characterize the coronary artery lesions in patients with NAFLD using coronary computed tomography angiography (CCTA). Overall, 101 patients with liver biopsy-proven NAFLD who had chest pain or electrocardiographic abnormalities underwent CCTA. Coronary artery lesions, including coronary artery stenosis (CAS), calcium score (CACS, Agatston score), and coronary artery non-calcified plaque were assessed using multi-slice CT. Multivariate analysis showed that age, smoking status, prevalence of dyslipidemia (DLP) and non-alcoholic steatohepatitis (NASH), and stage of fibrosis were independent risk factors for CAS. Age, and the prevalence of DM and DLP, were independent risk factors for CACS, and the prevalence of NASH tended to be an independent risk factor. In addition, the prevalence of DLP and NASH were independent risk factors for non-calcified plaques. Coronary artery lesions are more common in patients with NASH than in those with non-alcoholic fatty liver, suggesting a higher risk in patients with NASH. Therefore, patients with NASH should be closely followed, with particular vigilance for coronary artery diseases.

Assessment of separation methods for extracellular vesicles from human and mouse brain tissues and human cerebrospinal fluids

Extracellular vesicle (EV) is a unified terminology of membrane-enclosed vesicular species ubiquitously secreted by almost every cell type and present in all body fluids. They carry a cargo of lipids, metabolites, nucleic acids and proteins for their clearance from cells as well as for cell-to-cell communications. The exact composition of EVs and their specific functions are not well understood due to the underdevelopment of the separation protocols, especially those from the central nervous system including animal and human brain tissues as well as cerebrospinal fluids, and the low yield of proteins in the separated EVs. To understand their exact molecular composition and their functional roles, development of the reliable protocols for EV separation is necessary. Here we report the methods for EV separation from human and mouse unfixed frozen brain tissues by a sucrose step gradient ultracentrifugation method, and from human cerebrospinal fluids by an affinity capture method. The separated EVs were assessed for morphological, biophysical and proteomic properties of separated EVs by nanoparticle tracking analysis, transmission electron microscopy, and labeled and label-free mass spectrometry for protein profiling with step-by-step protocols for each assessment.

Diagnostic Utility of Serum Ascites Lipid and Protein Gradients in Differentiation of Ascites

CONTEXT

Ability of SAAG to differentiate malignant ascites from other aetiologies like tubercular peritonitis is a major problem. Alternate screening test is needed for differentiating ascites due to malignancy from those due to tubercular peritonitis.

AIMS

To study the diagnostic utility of serum ascites lipid gradients and serum ascites protein gradients in pathophysiological differentiation of ascites.

SETTINGS AND DESIGN

The present study is a prospective, descriptive, hospital-based, cross-sectional study.

METHODS AND MATERIAL

The study was conducted on patients with ascites who were admitted to General Medicine Department, Kasturba Hospital, Manipal. The study included 60 patients with ascites of different etiologies (liver cirrhosis, tubercular peritonitis, and malignant ascites). All of them had undergone clinical, laboratory, and imaging investigations and were treated as per standard of care. All patients underwent abdominal paracentesis, and fluid samples were sent for analysis.

STATISTICAL ANALYSIS USED

ANOVA, Kruskal-Wallis H test, and ROC curve analysis.

RESULTS

Among the gradients, only SAPG and SAAG had over all statistical significance (<0.005) among the groups, but no significance between malignancy and tubercular peritonitis had been observed. Similarly all the ascitic fluid parameters measured had an overall statistical significance (<0.005), but there was no significant difference observed between malignancy and tubercular peritonitis groups. However, ascitic fluid and serum HDL cholesterol had a statistical significance (<0.05) between malignancy and tubercular peritonitis.

CONCLUSIONS

With a cut-off value of 4, SAPG is one of best screening tests in differentiation of cirrhotic with noncirrhotic ascites when compared with SAAG, whereas it is a poor parameter with high sensitivity and very low specificity in differentiation of malignant with nonmalignant ascites. Also the present study reveals HDL cholesterol levels in ascitic fluid to be a valuable marker with higher sensitivity and specificity in differentiation of malignancy and tuberculosis peritonitis (i.e., differentiation of low SAAG ascites).

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY GUIDELINES FOR MANAGEMENT OF DYSLIPIDEMIA AND PREVENTION OF CARDIOVASCULAR DISEASE

OBJECTIVE

The development of these guidelines is mandated by the American Association of Clinical Endocrinologists (AACE) Board of Directors and American College of Endocrinology (ACE) Board of Trustees and adheres with published AACE protocols for the standardized production of clinical practice guidelines (CPGs).

METHODS

Recommendations are based on diligent reviews of the clinical evidence with transparent incorporation of subjective factors, according to established AACE/ACE guidelines for guidelines protocols.

RESULTS

The Executive Summary of this document contains 87 recommendations of which 45 are Grade A (51.7%), 18 are Grade B (20.7%), 15 are Grade C (17.2%), and 9 (10.3%) are Grade D. These detailed, evidence-based recommendations allow for nuance-based clinical decision-making that addresses multiple aspects of real-world medical care. The evidence base presented in the subsequent Appendix provides relevant supporting information for Executive Summary Recommendations. This update contains 695 citations of which 203 (29.2 %) are EL 1 (strong), 137 (19.7%) are EL 2 (intermediate), 119 (17.1%) are EL 3 (weak), and 236 (34.0%) are EL 4 (no clinical evidence).

CONCLUSION

This CPG is a practical tool that endocrinologists, other health care professionals, health-related organizations, and regulatory bodies can use to reduce the risks and consequences of dyslipidemia. It provides guidance on screening, risk assessment, and treatment recommendations for a range of individuals with various lipid disorders. The recommendations emphasize the importance of treating low-density lipoprotein cholesterol (LDL-C) in some individuals to lower goals than previously endorsed and support the measurement of coronary artery calcium scores and inflammatory markers to help stratify risk. Special consideration is given to individuals with diabetes, familial hypercholesterolemia, women, and youth with dyslipidemia. Both clinical and cost-effectiveness data are provided to support treatment decisions.

ABBREVIATIONS

4S = Scandinavian Simvastatin Survival Study A1C = glycated hemoglobin AACE = American Association of Clinical Endocrinologists AAP = American Academy of Pediatrics ACC = American College of Cardiology ACE = American College of Endocrinology ACS = acute coronary syndrome ADMIT = Arterial Disease Multiple Intervention Trial ADVENT = Assessment of Diabetes Control and Evaluation of the Efficacy of Niaspan Trial AFCAPS/TexCAPS = Air Force/Texas Coronary Atherosclerosis Prevention Study AHA = American Heart Association AHRQ = Agency for Healthcare Research and Quality AIM-HIGH = Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides trial ASCVD = atherosclerotic cardiovascular disease ATP = Adult Treatment Panel apo = apolipoprotein BEL = best evidence level BIP = Bezafibrate Infarction Prevention trial BMI = body mass index CABG = coronary artery bypass graft CAC = coronary artery calcification CARDS = Collaborative Atorvastatin Diabetes Study CDP = Coronary Drug Project trial CI = confidence interval CIMT = carotid intimal media thickness CKD = chronic kidney disease CPG(s) = clinical practice guideline(s) CRP = C-reactive protein CTT = Cholesterol Treatment Trialists CV = cerebrovascular CVA = cerebrovascular accident EL = evidence level FH = familial hypercholesterolemia FIELD = Secondary Endpoints from the Fenofibrate Intervention and Event Lowering in Diabetes trial FOURIER = Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects With Elevated Risk trial HATS = HDL-Atherosclerosis Treatment Study HDL-C = high-density lipoprotein cholesterol HeFH = heterozygous familial hypercholesterolemia HHS = Helsinki Heart Study HIV = human immunodeficiency virus HoFH = homozygous familial hypercholesterolemia HPS = Heart Protection Study HPS2-THRIVE = Treatment of HDL to Reduce the Incidence of Vascular Events trial HR = hazard ratio HRT = hormone replacement therapy hsCRP = high-sensitivity CRP IMPROVE-IT = Improved Reduction of Outcomes: Vytorin Efficacy International Trial IRAS = Insulin Resistance Atherosclerosis Study JUPITER = Justification for the Use of Statins in Primary Prevention: An Intervention Trial Evaluating Rosuvastatin LDL-C = low-density lipoprotein cholesterol Lp-PLA2 = lipoprotein-associated phospholipase A2 MACE = major cardiovascular events MESA = Multi-Ethnic Study of Atherosclerosis MetS = metabolic syndrome MI = myocardial infarction MRFIT = Multiple Risk Factor Intervention Trial NCEP = National Cholesterol Education Program NHLBI = National Heart, Lung, and Blood Institute PCOS = polycystic ovary syndrome PCSK9 = proprotein convertase subtilisin/kexin type 9 Post CABG = Post Coronary Artery Bypass Graft trial PROSPER = Prospective Study of Pravastatin in the Elderly at Risk trial QALY = quality-adjusted life-year ROC = receiver-operator characteristic SOC = standard of care SHARP = Study of Heart and Renal Protection T1DM = type 1 diabetes mellitus T2DM = type 2 diabetes mellitus TG = triglycerides TNT = Treating to New Targets trial VA-HIT = Veterans Affairs High-Density Lipoprotein Cholesterol Intervention Trial VLDL-C = very low-density lipoprotein cholesterol WHI = Women's Health Initiative.

Pharmacological Management of Dyslipidemia in Atherosclerosis: Limitations, Challenges, and New Therapeutic Opportunities

Clinical and epidemiological studies during the last 7 decades indicated that elevated low-density lipoprotein cholesterol (LDL-C) levels and reduced high-density lipoprotein cholesterol (HDL-C) levels correlate with the pathogenesis and progression of atherosclerotic lesions in the arterial wall. This observation led to the development of LDL-C-lowering drugs for the prevention and treatment of atherosclerosis, some with greater success than others. However, a body of recent clinical evidence shows that a substantial residual cardiovascular risk exists even at very low levels of LDL-C, suggesting that new therapeutic modalities are still needed for reduction of atherosclerosis morbidity and mortality. Unfortunately, HDL-C-raising drugs developed toward this goal had disappointing results thus far. Here, we critically review the literature presenting available evidence and challenges that need to be met and discuss possible new avenues for the development of novel lipid pharmacotherapeutics to reduce the burden of atherosclerosis.

Impact of the modified Atkins diet on cardiovascular health in adults with epilepsy

AIM

The current study investigated biochemical and vascular markers of cardiovascular health in adult patients with epilepsy treated with long-term (greater than 1year) ketogenic diet therapy compared with controls.

METHOD

Anthropometric measures, serum fasting lipid panel, apolipoproteins A-1 and B, lipoprotein sub-fractions as well as common carotid intima-media thickness (cIMT), and plaque presence were assessed in 20 adult patients with epilepsy on a modified Atkins diet (MAD) for >1year started as an adult compared with 21 adult patients with epilepsy naïve to diet therapy.

RESULTS

Patients treated with MAD had significantly lower weight, body mass index, waist and hip circumference, percent body fat, and serum triglyceride levels when compared with control patients. In contrast, they had significantly higher serum levels of small low-density-lipoprotein (LDL) particles and were significantly more likely to have LDL pattern B in which small LDL particles predominate when compared with controls. However, there was no significant difference in cIMT or plaque presence between groups.

CONCLUSION

Our results provide clinical evidence demonstrating the cardiovascular safety of a high-fat, low-carbohydrate diet used in adults with epilepsy for at least 12months. It also highlights potential markers of cardiovascular risk - small dense LDL particles - that should be closely monitored in adults treated with diet therapy long-term.

Present therapeutic role of cholesteryl ester transfer protein inhibitors

Therapeutic interventions aimed at increasing high-density lipoprotein (HDL) levels in order to reduce the residual cardiovascular (CV) risk of optimally drug treated patients have not provided convincing results, so far. Transfer of cholesterol from extrahepatic tissues to the liver appears to be the major atheroprotective function of HDL, and an elevation of HDL levels could represent an effective strategy. Inhibition of the cholesteryl ester transfer protein (CETP), raising HDL-cholesterol (HDL-C) and apolipoprotein A-I (apoA-I) levels, reduces low-density lipoprotein-cholesterol (LDL-C) and apoB levels, thus offering a promising approach. Despite the beneficial influence on cholesterol metabolism, off-target effects and lack of reduction in CV events and mortality (with torcetrapib, dalcetrapib and evacetrapib) highlighted the complex mechanism of CETP inhibition. After the failure of the above mentioned inhibitors in phase III clinical development, possibly due to the short duration of the trials masking benefit, the secondary prevention REVEAL trial has recently shown that the inhibitor anacetrapib significantly raised HDL-C (+104%), reduced LDL-C (-18%), with a protective effect on major coronary events (RR, 0.91; 95%CI, 0.85-0.97; p = 0.004). Whether LDL-C lowering fully accounts for the CV benefit or if HDL-C-rise is a crucial factor still needs to be determined, although the reduction of non-HDL (-18%) and Lp(a) (-25%), should be also taken into account. In spite of the positive results of the REVEAL Study, Merck decided not to proceed in asking regulatory approval for anacetrapib. Dalcetrapib (Dal-GenE study) and CKD-519 remain the two molecules within this area still in clinical development.

Method for estimating high sdLDL-C by measuring triglyceride and apolipoprotein B levels

Background

We previously developed an assay to directly measure small dense (sd) low-density lipoprotein cholesterol (LDL-C) levels, which is not widely used in general clinical practice. Therefore, we propose a simpler method, “LDL window,” that uses conventional methods for estimating high sdLDL-C levels.

Methods

We analyzed our previous studies (2006–2008) on healthy subjects and patients with type 2 diabetes and coronary artery disease (CAD). The sdLDL-C level was measured using the precipitation method, and LDL size was determined using gradient gel electrophoresis. The “LDL window” comprises the estimation of LDL particle number and size. We adopted apolipoprotein B (apoB) for the estimation of the LDL particle number and used 110 mg/dL as the cutoff value for hyper-apoB. Triglycerides (TGs) are a powerful inverse determinant of LDL particle size. Therefore, we adopted TG for the estimation of the LDL particle size and used 150 mg/dL as the cutoff value for hyper-TG. Subjects were stratified into the following four subgroups: normal, hyper-TG, hyper-apoB, and hyper-TG/-apoB. Non-high-density lipoprotein cholesterol (non-HDL-C) is a surrogate marker for apoB; therefore, the “alternative LDL window” comprised non-HDL-C (cutoff, 170 mg/dL) and TG.

Results

The top quartile (Q4) of sdLDL-C (>31 mg/dL) doubled in patients with diabetes and CAD. The hyper-TG/-apoB group in the “LDL window” represented >90% Q4 and <4% Q1 and Q2, irrespective of the subjects. The sdLDL-C levels in the hyper-TG/-apoB group were 50% higher in patients with diabetes and CAD than those in controls. Similar results were obtained using the “alternative LDL window.”

Conclusions

Our proposed “LDL window” may help identify patients at high risk of CAD independent of LDL-C.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0417-6) contains supplementary material, which is available to authorized users.

Reducing cardiovascular risk in patients with type 2 diabetes: the potential contribution of nicotinic acid

Current treatment guidelines highlight the increased cardiovascular risk associated with type 2 diabetes and identify the need for intensive risk factor management. Dyslipidaemia characterised by elevated serum triglycerides, low levels of high-density lipoprotein cholesterol (HDL-C) and an increase in small, dense low-density lipoprotein cholesterol (LDL-C) particles (the lipid triad), is one of the most important modifiable cardiovascular risk factors in patients with type 2 diabetes. Statins, which are effective in reducing LDL-C, are currently considered the foundation of lipid-lowering treatment in type 2 diabetes, in addition to lifestyle modification. Increasingly, guidelines also identify low HDL-C as an important secondary priority for treatment. Of the available treatment options, both fibrates and nicotinic acid are effective in treating dyslipidaemia associated with type 2 diabetes, although the latter has greater potency in raising HDL-C. Based on its profile of activity, addition of nicotinic acid to primary statin therapy would be a logical strategy in the treatment of diabetic dyslipidaemia. Outcome data from large prospective studies are awaited to confirm the potential morbidity and mortality benefits of this approach.

Twice weekly intake of farmed Atlantic salmon (Salmo salar) positively influences lipoprotein concentration and particle size in overweight men and women

The US Dietary Guidelines for Americans recommend twice weekly fish intake. Farmed Atlantic salmon is a good source of omega-3 (n-3) fatty acids which have positive lipid modifying effects; however, it is unknown whether these responses are dose-dependent. Our primary research objective was to determine the effect of dose-dependent intake of farmed Atlantic salmon on lipoprotein particle (P) size and concentration. We hypothesized that low-density lipoprotein (LDL)-P and high-density lipoprotein (HDL)-P size and concentration would increase with salmon intake in a dose-dependent manner. Overweight, adult participants (n = 19) were enrolled in a cross-over designed clinical trial evaluating intake of farmed Atlantic salmon. In random order, participants were assigned to 90, 180, or 270 g of salmon twice weekly for 4-week dietary treatments. Following a 4- to 8-week washout, participants crossed over to another dose of fish intake until all treatments were completed. Plasma lipid concentrations were determined and serum lipoprotein concentrations and particle size were determined by nuclear magnetic resonance. Intake of salmon reduced plasma and serum triglyceride (TG) concentrations and increased plasma HDL-C concentrations. The concentrations of large very low-density lipoprotein (VLDL)-P and chylomicron (CM)-P were reduced. Large LDL-P concentrations were increased in a dose-dependent manner. The mean size of VLDL-P was reduced and that of LDL was increased. Total TG was reduced as was the TG content of VLDL-P and CM-P. Twice weekly intake of farmed Atlantic salmon portions influences lipoprotein particle size and concentration in a manner associated with cardiovascular disease risk reduction.

Bergamot Reduces Plasma Lipids, Atherogenic Small Dense LDL, and Subclinical Atherosclerosis in Subjects with Moderate Hypercholesterolemia: A 6 Months Prospective Study

Background: Some patients experience statin-induced side effects or prefer nutraceutical approaches for the treatment of dyslipidemia. This has led to a search for alternative therapeutic approaches for dyslipidemia management. In recent studies Citrus bergamia (known as Bergamot) juice was able to reduce serum levels of lipids. Such benefit may be attributed to high amounts of flavonoids contained in Bergamot fruit juice (neoeriocitrin, neohesperidin, naringin). The aim of the present study was to fully investigate the effects of a Bergamot extract on cardio-metabolic parameters, including plasma lipids, atherogenic lipoproteins and subclinical atherosclerosis.

Methods: Eighty subjects (42 men and 38 women, mean age: 55 ± 13 years) with moderate hypercholesterolemia [e.g., with plasma LDL-cholesterol concentrations between 160 and 190 mg/dl (between 4.1 and 4.9 mmol/l)] were included. A Bergamot-derived extract (Bergavit R^®) was given at a fixed dose daily (150 mg of flavonoids, with 16% of neoeriocitrin, 47% of neohesperidin and 37% of naringin) for 6 months. Lipoprotein subfractions were assessed by gel electrophoresis. With this methodology low density lipoprotein (LDL) subclasses are distributed as seven bands (LDL-1 and -2 as large LDL, and LDL-3 to -7 as atherogenic small, dense LDL). Subclinical atherosclerosis was assessed by carotid intima-media thickness (cIMT) using B-mode ultrasound.

Results: After 6 months, Bergavit R^® reduced total cholesterol (from 6.6 ± 0.4 to 5.8 ± 1.1 mmol/l, p < 0.0001), triglycerides (from 1.8 ± 0.6 to 1.5 ± 0.9 mmol/l, p = 0.0020), and LDL-cholesterol (from 4.6 ± 0.2 to 3.7 ± 1.0 mmol/l, p < 0.0001), while HDL- cholesterol increased (from 1.3 ± 0.2 to 1.4 ± 0.4 mmol/l, p < 0.0007). In addition, a significant increase in LDL-1 (from 41.2 ± 0.2 to 49.6 ± 0.2%, p < 0.0001) was accompanied by decreased small, dense LDL-3, -4, and 5 particles (from 14.5 ± 0.1 to 9.0 ± 0.1% p < 0.0001; 3.2 ± 0.1 to 1.5 ± 0.1% p = 0.0053; 0.3 ± 0.0% to 0.1 ± 0.0% p = 0.0133, respectively). cIMT also decreased from 1.2 ± 0.4 to 0.9 ± 0.1 mm (p < 0.0001).

Conclusion: This is the first study investigating the effects of Bergamot flavonoids supplementation on cardio-metabolic risk in dyslipidemic subjects. Bergavit R^® (Bergamot juice extract) supplementation significantly reduced plasma lipids and improved the lipoprotein profile. cIMT was also reduced significantly over a relatively short time frame of 6 months.

Cytokeratin 8 in Association with sdLDL and ELISA Development

BACKGROUND

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide. Cytokeratins (CKs) which may also be expressed in vascular smooth muscle cells (SMCs) are generally considered to be markers for the differentiation of epithelial cells. Small, dense, low-density lipoprotein (sdLDL) particles, also termed LDL-IV, independently predict risk of CVD.

AIMS

The aims of this study were to develop an analytical method, apart from ultracentrifugation capable of isolating sdLDL in order to study any associated proteins.

MATERIALS AND METHODS

Using modified gradient gel electrophoresis (GGE), de-identified sdLDL-enriched plasma was used to physically elute and isolate sdLDL particles. To validate the finding, additional plasma from 77 normal and 48 higher risk subjects were used to measure sdLDL particles and CK8. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting method were used to identify the characteristics of proteins associated with sdLDL. An enzyme-linked immunosorbent assay (ELISA) method was developed and validated for the measurement of CK8 in plasma.

RESULTS

The validation of the CK8 ELISA method showed good analytical performance. The isolated sdLDL particles were verified with nondenaturing GGE with the apolipoprotein B component confirmed by Western immunoblotting. Confirmed by SDS-PAGE and Western immunoblotting, CK8 was associated with sdLDL. Two-tailed statistical analysis showed that CK8 and sdLDL particles were significantly higher in the high-risk CVD group compared to control group (P < 0.01 and P < 0.01, respectively).

CONCLUSION

This study reports a novel association between CK8 and sdLDL in individuals with CVD who have a predominance of sdLDL.

Cholesterol Metabolism in CKD

Patients with chronic kidney disease (CKD) have a substantial risk of developing coronary artery disease. Traditional cardiovascular disease (CVD) risk factors such as hypertension and hyperlipidemia do not adequately explain the high prevalence of CVD in CKD. Both CVD and CKD are inflammatory states and inflammation adversely affects lipid balance. Dyslipidemia in CKD is characterized by elevated triglyceride levels and high-density lipoprotein levels that are both decreased and dysfunctional. This dysfunctional high-density lipoprotein becomes proinflammatory and loses its atheroprotective ability to promote cholesterol efflux from cells, including lipid-overloaded macrophages in the arterial wall. Elevated triglyceride levels result primarily from defective clearance. The weak association between low-density lipoprotein cholesterol level and coronary risk in CKD has led to controversy over the usefulness of statin therapy. This review examines disrupted cholesterol transport in CKD, presenting both clinical and preclinical evidence of the effect of the uremic environment on vascular lipid accumulation. Preventative and treatment strategies are explored.

Relation of fish oil supplementation to markers of atherothrombotic risk in patients with cardiovascular disease not receiving lipid-lowering therapy

Fish oil supplementation (FOS) is known to have cardiovascular benefits. However, the effects of FOS on thrombosis are incompletely understood. We sought to determine if the use of FOS is associated with lower indices of atherothrombotic risk in patients with suspected coronary artery disease (sCAD). This is a subgroup analysis of consecutive patients with sCAD (n=600) enrolled in the Multi-Analyte, Thrombogenic, and Genetic Markers of Atherosclerosis study. Patients on FOS were compared with patients not on FOS. Lipid profile was determined by vertical density gradient ultracentrifugation (n=520), eicosapentaenoic acid+docosahexaenoic acid was measured by gas chromatography (n=437), and AtherOx testing was performed by immunoassay (n=343). Thromboelastography (n=419), ADP- and collagen-induced platelet aggregation (n=137), and urinary 11-dehydrothromboxane B2 levels (n=259) were performed immediately before elective coronary angiography. In the total population, FOS was associated with higher eicosapentaenoic acid+docosahexaenoic acid content (p<0.001), lower triglycerides (p=0.04), total very low-density lipoprotein cholesterol (p=0.002), intermediate-density lipoprotein cholesterol (p=0.02), and AtherOx levels (p=0.02) but not in patients on lipid-lowering therapy. Patients not on lipid-lowering therapy taking FOS had lower very low-density lipoprotein cholesterol, intermediate-density lipoprotein cholesterol, remnant lipoproteins, triglycerides, low-density lipoprotein cholesterol, AtherOx levels, collagen-induced platelet aggregation, thrombin-induced platelet-fibrin clot strength, and shear elasticity (p<0.03 for all). In clopidogrel-treated patients, there was no difference in ADP-induced aggregation between FOS groups. Patients on FOS had lower urinary 11-dehydrothromboxane B2 levels regardless of lipid-lowering therapy (p<0.04). In conclusion, the findings of this study support the potential benefit of FOS for atherothrombotic risk reduction in sCAD with the greatest benefit in patients not receiving lipid-lowering therapy. Future prospective studies to compare FOS with lipid-lowering therapy and to assess the independent effects of FOS on thrombogenicity are needed.

LDL-migration index (LDL-MI), an indicator of small dense low-density lipoprotein (sdLDL), is higher in non-alcoholic steatohepatitis than in non-alcoholic fatty liver: a multicenter cross-sectional study

Background

Non-alcoholic fatty liver disease (NAFLD) is associated with increased risks of atherosclerotic diseases, including cardiovascular disease. However, the difference in risk between patients with non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH) has not yet been determined. Accumulating evidence has shown that high amounts of small dense low-density lipoprotein (sdLDL) are closely associated with atherosclerotic diseases. This study investigated differences in risk factors for atherosclerotic diseases, especially LDL-migration index (LDL-MI), an indicator of sdLDL, between patients with NAFL and NASH.

Methods

LDL-MI was analyzed in a primary cohort of 156 patients with NAFLD, including 53 with NAFL and 103 with NASH, and a validation cohort of 69 patients with NAFLD, including 25 with NAFL and 44 with NASH.

Results

In the primary cohort, NASH was associated with elevated LDL-MI (p = 0.039). Multiple regression analysis showed that NASH and the non-use of lipid lowering medications were independently correlated with higher LDL-MI in all patients with NAFLD. Among patients not on lipid lowering medications, those with NASH had significantly higher LDL-MI than those with NAFL (p = 0.001). These findings were confirmed in a validation cohort, in that LDL-MI was significantly higher in patients with NASH than with NAFL (p = 0.043).

Conclusion

This study is the first to show that LDL-MI, an indicator of sdLDL, was higher in patients with NASH than with NAFL, suggesting that the risk of atherosclerotic diseases may be higher in NASH than NAFL. Patients with NASH should be followed closely, especially for the progression of liver pathology and atherosclerotic diseases.

Trial Registration

UMIN000009614

High-density lipoprotein subfractions in relation with the severity of coronary artery disease: A Gensini score assessment

BACKGROUND

The exact role of different high-density lipoprotein (HDL) subfractions in the pathogenesis of coronary artery disease (CAD) has not yet been fully explored. The aim of the present study was to examine the relationship between HDL subfractions and the severity of CAD in patients without statin therapy.

METHODS

A total of 382 consecutive patients (mean: 55.36 ± 11.30 years of age) who underwent coronary angiography from angina-like chest pain were investigated. Patients were classified into 2 groups according to the angiographic results: a CAD group (n = 283) and a control group (n = 99). The distribution of HDL subfractions was analyzed using a Quantimetrix Lipoprint HDL system. CAD severity was measured by Gensini score (GS).

RESULTS

Compared with the control group, HDL-cholesterol (HDL-C), large HDL-C level, and the large HDL subfraction percentages in the CAD group were significantly lower (P = .002, P < .001, P < .001, respectively). Meanwhile, a small HDL-C level and the percentage of small HDL subfraction were significantly higher (P = .003, P < .001, respectively). Correlation analysis showed that the percentage of a large HDL subfraction was negatively correlated with GS (β = -0.191, P = .005), whereas the percentage of a small HDL subfraction positively correlated with GS (β = 0.145, P = .023) in patients with CAD.

CONCLUSIONS

Small HDL subfraction was associated with the presence of CAD, whereas the percentage of large HDL and small HDL subfraction was negatively and positively associated with the severity of CAD, respectively.

Nonalcoholic steatohepatitis is associated with an atherogenic lipoprotein subfraction profile

Background

Nonalcoholic steatohepatitis (NASH) carries an increased risk of cardiovascular disease (CVD) relative to the general population. We sought to evaluate whether differences in lipoprotein subfractions in obese patients with and without NASH contributes to this difference in CVD risk.

Findings

Ion mobility analysis was performed on 78 individuals with obesity undergoing weight loss surgery. All individuals had standard of care liver biopsies performed during surgery. Patients with NASH had significantly smaller peak LDL diameter (P = 0.02, 219.0 Å vs. 222.6 Å), and levels of IDL2 (P = 0.01, 104. nmol/L vs. 133.4 nmol/L) and HDL2b (P = 0.05, 676.7 nmol/L vs. 880.1 nmol/L) compared to those without NASH. NASH patients had significantly higher LDL-IVb levels than those without NASH (P = 0.02, 49.0 nmol/L vs. 37.1 nmol/L).

The inverse association of LDL peak diameter with NASH remained significant after adjustment for diabetes (P = 0.02). HDL2b levels were inversely correlated with hepatocyte ballooning and NASH and these remained significant after adjustment for diabetes (P = 0.0017 and P = 0.007, respectively). IDL2 levels were inversely correlated with NASH, hepatocyte ballooning and fibrosis stage but these were not significant after adjustment for diabetes.

Conclusions

The lipoprotein subfraction profile in subjects with NASH is characterized by small peak LDL diameter, reduced HDL2b levels and elevated LDL-IVb levels. These changes may contribute to the increased CVD seen in patients with NASH.

Elevated small dense low-density lipoprotein cholesterol as a predictor for future cardiovascular events in patients with stable coronary artery disease

AIM

The aim of the present study was to investigate how small dense low-density lipoprotein cholesterol (sdLDL-C) compared with LDL-C affect the long-term prognosis in patients with stable coronary artery disease (CAD).

METHODS

sdLDL-C measured by heparin magnesium precipitation and LDL particle size measured by non-denatured gradient-gel electrophoresis were compared in 190 consecutive CAD patients who underwent coronary arteriography between 2003 and 2004 who did or did not develop cardiovascular events during a seven-year follow-up period. Cardiovascular events were death caused by cardiovascular diseases(CVDs), onset of acute coronary syndrome, need for coronary and peripheral arterial revascularization, hospitalization for heart failure, surgical procedure for any CVDs, and/or hospitalization for stroke.

RESULTS

First-time cardiovascular events were observed in 72 patients. Those who experienced cardiovascular events were older and had higher prevalence rates of hypertension and diabetes; significantly higher Gensini coronary atherosclerotic scores; significantly higher levels of sdLDL-C, sdLDL-C/LDL-C, and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratios; and greater glycated hemoglobin(Hb)A1c and brain natriuretic peptide (BNP) levels. They also had significantly smaller LDL particle sizes, HDL-C, apolipoprotein A-1, and estimated glomerular filtration rate (GFR) compared with patients without cardiovascular events. Conversely, LDL-C, non-HDL-C, apolipoprotein B, remnantlike particle cholesterol, and high-sensitivity C-reactive protein (hs-CRP) levels were similar between the two groups. A Kaplan-Meyer event-free survival curve demonstrated that patients with sdLDL-C≥35 mg/dL (median level) had significantly poorer prognosis compared with those with lower sdLDL-C levels, while patients with LDL-C ≥100 mg/dL had a non-significantly lower survival rate.

CONCLUSION

These results confirm that sdLDL-C is a very promising biomarker to predict future cardiovascular events in the secondary prevention of stable CAD.

Intercorrelations of lipoprotein subfractions and their covariation with lifestyle factors in healthy men

So far, little is known about the effect of nutrition and lifestyle on the composition of circulating lipoprotein subfractions. In the current study, we measured the correlations among physical activity, nutrient intake, smoking, body-mass index (BMI), and age with the concentration of triglycerides, cholesterol, phospholipids, and apolipoproteins (ApoA1, ApoA2 and ApoB) in subfractions of LDL and HDL in 265 healthy working men. Concentrations of cholesterol, phospholipids, and ApoB in small, dense atherogenic LDL particles (sdLDL) correlated negatively (p<0.001) with those of cholesterol, phospholipids, and ApoA1 in HDL2, respectively. Age correlated positively with sdLDL while increasing BMI correlated with an atherogenic shift of cholesterol, phospholipids, and ApoB from large, buoyant LDL (lbLDL) to sdLDL and decreasing concentrations of HDL2 constituents. Physical activity and alcohol intake correlated negatively with sdLDL constituents and positively with HDL2 components. Consumption of monounsaturated fatty acids (MUFA) correlated with a lower ratio of sdLDL to HDL2 cholesterol. A favorable lipoprotein subfraction profile linked to a reduced risk of cardiovascular disease in men was associated with physical activity, moderate alcohol consumption, and dietary intake of MUFA, which might be exploited in future interventions for prevention of age- and BMI-associated atherogenic shifts of lipoprotein subfractions.

Comparison of four methods of analysis of lipoprotein particle subfractions for their association with angiographic progression of coronary artery disease

BACKGROUND

Compare gradient gel electrophoresis (GGE), vertical auto profile ultracentrifugation (VAP-II), nuclear magnetic resonance spectroscopy (NMR), and ion mobility for their ability to relate low- (LDL), intermediate- (IDL), very-low-density (VLDL) and high-density lipoprotein (HDL) subfraction concentrations to atherosclerotic progression.

METHODS AND RESULTS

Regression analyses of 136 patients who received baseline and follow-up coronary angiographies and subfraction measurements by all four methods in the HDL Atherosclerosis Treatment Study. Prior analyses have shown that the intervention primarily affected disease progression in proximal arteries with <30% stenoses at baseline. Three-year increases in percent stenoses were consistently associated with higher on-study plasma concentrations of small, dense LDL as measured by GGE (LDLIIIb, P=10(-6); LDLIVa, P=0.006; LDLIVb, P=0.02), VAP-II (LDL4, P=0.002), NMR (small LDL, P=0.001), and ion mobility (LDL IIb, P=0.04; LDLIIIa, P=0.002; LDLIIIb, P=0.0007; LDLIVa, P=0.05). Adjustment for triglycerides, HDL-cholesterol, and LDL-cholesterol failed to eliminate the statistical significance for on-study GGE estimated LDLIIIb (P=10(-5)) and LDLIVa (P=0.04); NMR-estimated small LDL (P=0.03); or ion mobility estimated large VLDL (P=0.02), LDLIIIa (P=0.04) or LDLIIIb (P=0.02). All methods show that the effects were significantly greater for the on-study than the baseline small, dense LDL concentrations, thus establishing that the values concurrent to the progression of disease were responsible. The rate of disease progression was also related to individual VLDL, IDL, and HDL subclasses to differing extents among the various analytic methods.

CONCLUSION

Four methodologies confirm the association of small, dense LDL with greater coronary atherosclerosis progression, and GGE, NMR, and ion mobility confirm that the associations were independent of standard lipid measurements.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov/ct2/show/NCT00000553.

Dietary cholesterol, heart disease risk and cognitive dissonance

In the 1960s, the thesis that dietary cholesterol contributes to blood cholesterol and heart disease risk was a rational conclusion based on the available science at that time. Fifty years later the research evidence no longer supports this hypothesis yet changing the dietary recommendation to limit dietary cholesterol has been a slow and at times contentious process. The preponderance of the clinical and epidemiological data accumulated since the original dietary cholesterol restrictions were formulated indicate that: (1) dietary cholesterol has a small effect on the plasma cholesterol levels with an increase in the cholesterol content of the LDL particle and an increase in HDL cholesterol, with little effect on the LDL:HDL ratio, a significant indicator of heart disease risk, and (2) the lack of a significant relationship between cholesterol intake and heart disease incidence reported from numerous epidemiological surveys. Over the last decade, many countries and health promotion groups have modified their dietary recommendations to reflect the current evidence and to address a now recognised negative consequence of ineffective dietary cholesterol restrictions (such as inadequate choline intake). In contrast, health promotion groups in some countries appear to suffer from cognitive dissonance and continue to promote an outdated and potentially hazardous dietary recommendation based on an invalidated hypothesis. This review evaluates the evidence for and against dietary cholesterol restrictions and the potential consequences of such restrictions.

Activation of paraoxonase 1 is associated with HDL remodeling ex vivo

BACKGROUND

We hypothesize that during high density lipoprotein (HDL) remodeling PON1 reaches an optimal distribution in HDL subclasses by which it achieves maximum activity. We conducted this study to gain insight on PON1 fate and activation during short-term HDL remodeling ex vivo.

METHODS

Serum from 8 healthy volunteers was either frozen at -80°C (time 0) or incubated under sterile conditions for up to 48h at 37°C or at 4°C. Aliquots were taken at 3, 6, 9, 24 and 48 h and immediately frozen at -80°C. PON1 activities were measured, as well as PON1 and apolipoprotein distributions in HDL subclasses by gradient gel electrophoresis.

RESULTS

The first novel finding in our study is the evidence provided for a significant activation of both lactonase and arylesterase activities of PON1 that ensues in a very short time frame of incubation of serum ex vivo at 37°C. All subjects studied displayed these changes, the activation was apparent in <3h, peaked at 6h and amounted to >20%. This is associated with a temperature and time-dependent redistribution of PON1 activity in HDL subclasses, with an increase in activity in both very large HDL2 and small HDL3 in the first phase (3-9h), followed by a progressive transfer of PON1 to very large HDL2 as the particles mature. These changes are paralleled by the appearance of weak, but apparent PON1 activity at subspecies that correspond to sdLDL. During the first phase of PON1 activation and shifts, a parallel shift of apoE can be evidenced: at 3-9h, apoE increases in sdLDL, after that time it is lost from HDL and also from sdLDL and stays in VLDL at the origin of the run. ApoA-I shifts towards larger particles, which parallels the change in PON1. As HDL matures there is a progressive shift of apoA-II towards larger HDL. Low levels of apoA-IV at the initiation of the incubation are followed by time dependent quick disappearance of apoA-IV in HDL which parallels the changes in PON1, apoE and A-II.

CONCLUSION

Short, ex vivo incubation of serum leads to quick activation of PON1 associated with transfers to HDL3c, large HDL and sdLDL. The process is blocked by CETP and LCAT inhibitors. The data suggest that HDL maturation optimizes PON1 activity. These findings may be of interest for future studies aimed at modulating PON-1 activity for its cardioprotective effects and suggest a new mechanism whereby CETP inhibitors failed in clinical trials.

Evaluation of association between atherogenic index of plasma and intima-media thickness of the carotid artery for subclinic atherosclerosis in patients on maintenance hemodialysis

Incidence of cardiovascular diseases in the patients having chronic kidney disease (CKD) is between 25% and 60%. This increased rate is proposed to be associated with "accelerated atherosclerosis." Increased carotid intima-media thickness (CIMT) is a subclinical atherosclerosis marker. Small-dense low-density lipoprotein particles are a strong risk factor for atherosclerosis. It was shown that atherogenic index of plasma (AIP = log(TG/HDL-c)) is correlated with size of the lipoprotein particles. We investigated the correlation between AIP and CIMT which is a subclinical atherosclerosis marker, in hemodialysis (HD) patients. A total of 62 persons with 31 patients under HD therapy and 31 volunteers were included in the study. In all the participants, CIMT was measured and AIP were calculated. AIP and CIMT values of the participants were compared with blood pressures, lipid profiles and the other risk factors. AIP (0.39 ± 0.32) and CIMT (0.57 ± 0.13) were found significantly higher in the patient group than in the controls (0.04 ± 0.36 and 0.45 ± 0.119, respectively); (P = 0.0001 and 0.0001, respectively). There was a significant correlation between AIP and increased CIMT in the patient group (P = 0.0001, r = 0.430). Among the lipid parameters, the strongest correlation was found between CIMT and AIP. We demonstrated the significant increase of AIP and CIMT in HD patients. A correlation was found between AIP and CIMT. AIP was found to show a correlation with a greater number of risk factors, both classical and CKD specific, than CIMT. These data suggest that AIP might be a method which can be used both in diagnosis of subclinical atherosclerosis and in deceleration processes of its progression.

Levels of cholesterol in small LDL particles predict atherosclerosis progression and incident CHD in the HDL-Atherosclerosis Treatment Study (HATS)

Objective

Test whether angiographically-documented changes in percent stenosis and clinical endpoints (coronary-related deaths, myocardial infarctions, stroke, revascularization for worsening ischemia) in the HDL-Atherosclerosis Treatment Study (HATS) were attributable to specific LDL-subclasses.

Methods

Gradient gel electrophoresis of on-study LDL-subclass cholesterol concentrations were measured in 32 placebo, 33 simvastatin-niacin, 38 antioxidant, and 39 simvastatin-niacin & antioxidant treated participants. The prespecified primary end point was the mean change per patient from the initial arteriogram to the final arteriogram in the percent stenosis caused by the most severe lesion in each of the nine proximal coronary segments.

Results

The change in the percent stenosis of the most severe proximal lesions increased in association with higher concentrations of the small LDL subfractions LDL-IIIb (24.2–24.6 nm) and LDL-IVa (23.3–24.1 nm) before (both P = 0.002) and after (P = 0.01 and P = 0.03 respectively) adjustment for treatment group and on-study HDL-cholesterol, LDL-cholesterol, and triglyceride concentrations. The associations appeared specific to lesions with <30% baseline stenosis. When adjusted for age, sex, baseline BMI and cigarette use, the odds for primary clinical endpoints (death from coronary causes, nonfatal myocardial infarction, stroke, or revascularization for worsening ischemia) were significantly greater in subjects with higher on-study LDL-IIIb levels both before (P = 0.01) and after (P = 0.03) adjustment for treatment group and the standard lipid values.

Conclusions

Plasma LDL-IIIb cholesterol concentrations were related to changes in coronary artery stenosis and cardiovascular events in patients with coronary artery disease and low HDL-cholesterol.

Trial Registration

ClinicalTrials.gov NCT00000553

Effects of dietary saturated fat on LDL subclasses and apolipoprotein CIII in men

Background/Objectives

Small dense LDL particles and apolipoprotein (apo) CIII are risk factors for cardiovascular disease (CVD) that can be modulated by diet, but there is little information regarding the effects of dietary saturated fat on their plasma levels. We tested the effects of high vs. low saturated fat intake in the context of a high beef protein diet on levels and composition of LDL subclasses and on apoCIII levels in plasma and LDL.

Subjects/Methods

Following consumption of a baseline diet (50% CHO, 13% protein, 38% total fat, 15% saturated fat) for 3 wk, 14 healthy men were randomly assigned to two reduced carbohydrate high beef protein diets (31% CHO, 31% protein, 38% fat) that differed in saturated fat content (15% vs. 8%) for 3 wk each in a crossover design.

Results

The high saturated fat diet resulted in higher mass concentrations of buoyant LDL I, medium density LDL II and dense LDL III, but not the very dense LDL IV; and significant increases in plasma and LDL apoCIII concentration of 9.4% and 33.5%, respectively. The saturated fat-induced changes in LDL apoCIII were specifically correlated with changes in apoCIII content of LDL IV.

Conclusions

Taken together with previous observations, these findings suggest that, at least in the context of a lower carbohydrate high beef protein diet, high saturated fat intake may increase CVD risk by metabolic processes that involve apoCIII.

The mean platelet volume and atherogenic index of plasma in nondipper normotensive individuals compared to dippers

Mean platelet volume (MPV) is a determinant of platelet activation. Atherogenic index of plasma (AIP), which is defined as the logarithm of the ratio of plasma level of triglycerides to the level of high-density lipoprotein (HDL)-cholesterol (log[ TG/HDL-C]), has recently been used as a marker of atherogenicity. This study included 104 normotensive individuals. Mean platelet volume and AIP were measured in all patients. Nondipper individuals (8.6 ± 0.9 fL, 0.3 ± 0.2) demonstrated higher values of MPV and AIP compared with dippers (7.9 ± 1.1 fL, 0.1 ± 0.2) (P < .001 and < .001, respectively). Mean platelet volume and AIP have a positive correlation with insufficient decline in nocturnal blood pressure.

Angiographically-assessed coronary artery disease associates with HDL particle size in women

It has been suggested that a reduced HDL particle size could be another feature of the atherogenic dyslipidemia found among viscerally obese subjects.

OBJECTIVE

To investigate, in women, the relationship between HDL particle size and coronary artery disease (CAD).

METHODS

Average HDL particle size was measured in a sample of 239 women on whom CAD was assessed by angiography.

RESULTS

Overall, women who had CAD were characterized by a deteriorated fasting metabolic risk profile, which was accompanied by smaller HDL particles compared to women without CAD (80.4 ± 2.2 Å vs. 81.5 ± 2.7 Å, p < 0.01). In addition, a reduced HDL particle size was a significant correlate of several features of the atherogenic metabolic profile of abdominal obesity such as increased triglyceride and apolipoprotein B concentrations, decreased HDL cholesterol levels, an elevated cholesterol/HDL cholesterol ratio and hyperinsulinemia and was also associated with an increased waist circumference (0.13≤|r|≤0.21, p < 0.05). Odds ratio of being affected by CAD was increased by 2.5-fold (95% CI: 1.4-4.5; p < 0.01) among women with smaller HDL particles compared to women with larger HDL particles. Finally, women characterized by the presence of the NCEP-ATP III clinical criteria or by hypertriglyceridemic waist were characterized by smaller HDL particles compared to women without these clinical phenotypes (p < 0.05).

CONCLUSION

HDL particle size appears to be another relevant feature of a dysmetabolic state which is related to CAD risk in women.

Determinants of low-density lipoprotein particle diameter during antiretroviral therapy including protease inhibitors in HIV-1-infected patients

BACKGROUND

Lipid disorders are frequent in HIV-1-infected patients taking combination antiretroviral therapy (cART) that includes protease inhibitors (PIs). The presence of small dense low-density lipoprotein particles might be an important predictive marker of cardiovascular disease in this setting. This cross-sectional substudy of the ANRS 126 trial was designed to identify variables influencing LDL diameter.

METHODS

We studied 81 stable HIV-1-infected patients with dyslipidaemia (LDL-cholesterol >4.1 mmol/l, triglycerides <8.8 mmol/l) receiving PI-including cART regimens and no lipid-lowering drugs. LDL diameter was assessed by gradient gel electrophoresis. Relationships between LDL diameter and demographic, metabolic and HIV-related variables were identified by using non-parametric univariate tests and multiple linear regression models.

RESULTS

In univariate analysis, LDL diameter was related to demographic variables, triglyceride (TG) levels, high-density lipoprotein cholesterol (HDL-c) levels, and the numbers and duration of exposure to nucleoside reverse transcriptase inhibitors and PIs. In multivariable linear regression analysis, LDL diameter was negatively associated with the TG level (P<0.0001) and positively associated with the HDL-c level (P<0.0001). For each 1-mmol/l increase in TG, LDL diameter fell by 0.281 nm. Conversely, for each 1-mmol/l increase in HDL-c, LDL diameter rose by 1.175 nm.

CONCLUSIONS

Higher TG and lower HDL-c levels are associated with smaller LDL particle diameter. Small-diameter LDL particles could contribute to early atherogenic processes in HIV-1-infected patients on cART.

Changes in lipoprotein subfraction concentration and composition in healthy individuals treated with the CETP inhibitor anacetrapib

We investigated the effects of the cholesteryl ester (CE) transfer protein inhibitor anacetrapib (ANA) on plasma lipids, lipoprotein subfraction concentrations, and lipoprotein composition in 30 healthy individuals. Participants (n = 30) were randomized to ANA 20 mg/day, 150 mg/day, or placebo for 2 weeks. Changes in concentration of lipoprotein subfractions were assessed using ion mobility, and compositional analyses were performed on fractions separated by density gradient ultracentrifugation. ANA 150 mg/day versus placebo resulted in significant decreases in LDL-cholesterol (26%) and apo B (29%) and increases in HDL-cholesterol (82%). Concentrations of medium and small VLDL, large intermediate density lipoprotein (IDL), and medium and small LDL (LDL2a, 2b, and 3a) decreased whereas levels of very small and dense LDL4b were increased. There was enrichment of triglycerides and reduction of CE in VLDL, IDL, and the densest LDL fraction. Levels of large buoyant HDL particles were substantially increased, and there was enrichment of CE, apo AI, and apoCIII, but not apoAII or apoE, in the mid-HDL density range. Changes in lipoprotein subfraction concentrations and composition with ANA 20 mg/day were similar to those for ANA 150 mg/day but were generally smaller in magnitude. The impact of these changes on cardiovascular risk remains to be determined.

Levels of apolipoproteins as risk factors for coronary artery disease

INTRODUCTION: The Saudi population is renowned for their unhealthy diet and physical inactivity. OBJECTIVE:To investigate apolipoproteins B (apo B), A-I (apo A-I) and B/A-I as risk factors that might be associated with increased incidence of the coronary artery disease. METHODS: Two hundred and twenty subjects suspected of having the coronary artery disease underwent coronary angiography and blood draw following a 12-hour fast. Apolipoproteins B and A-I were both measured by turbidimetric methods. RESULTS: One hundred and forty subjects were positive and 80 subjects were negative for the coronary artery disease. Both apolipoproteins were found to be statistically significant as risk factors for the coronary artery disease: apolipoprotein B (105.33±29.22 versus 94.56±24.35 mg/dL, p<0.003), apolipoprotein A-I (123.98±25.6 versus 133.5±24.1 mg/dL, p<0.004) and apolipoproteins B/A-I (0.88±0.28 versus 0.72±0.2, p<0.0001). CONCLUSIONS:Measurements of apolipoproteins B, A-I and calculation of apolipoproteins B/A-I ratio either instead of or in addition to the customary measurements of lipoprotein cholesterol may significantly add to predicting and assessing the coronary risk factors in the Saudi population.

Association of lipids with coronary heart disease in a saudi population

BACKGROUND: The Saudi population is known to have an unhealthy diet in addition to physical inactivity. OBJECTIVE: To investigate the lipid-mediated risk factors that might be associated with increased incidence of coronary heart diseasein the Saudi population as this was found in Western populations. MATERIALS AND METHODS: Two hundred and twenty subjects suspected of having coronary heart disease underwent coronary angiography and blood draw following a 12-hour fast. Total and HDL cholesterol, triglycerides, Lp(a) and lipoprotein lipase were measured by standard methods. Small, dense LDL was measured by the iodixanol method with an ultracentrifugation of only 2.5 hours. RESULTS: One hundred and forty subjects were found to be positive for coronary heart disease while 80 subjects were shown to be negative for this disease. Statistically significant risk factors for coronary heart disease in the Saudi population were hypertriglyceridemia (1.93±0.95 versus1.45±0.16 mmol/L;p<0.0001); low HDL cholesterol (1.09±0.55 vs 1.33±0.63 mmol/L, p=0.0001); high Lp(a) (46.8±45.58 versus 29.06±17.03 mg/dL;p=0.019); and the presence of small, dense LDL (1.0314±0.0028 versus 1.0300±0.0003 g/kg;p=0.0099). Total cholesterol (4.99±1.11 versus 4.75±1.11 mmol/L;p=0.099), LPL (35.56±26.6 versus 27.89±11.96 IU/L;p<0.059), and LDL cholesterol (3.06±1.12 versus 2.79±1.08 mmol/L;p=0.08) were not found to be statistically significant coronary heart disease risk factors. CONCLUSIONS: This study indicates that high TG, low HDL, high Lp(a) and the presence of small, dense LDL may contribute to the incidence of coronary heart disease and that TC was not significantly associated with incidence of coronary heart disease in the Saudi population.

Consumption of high-oleic acid ground beef increases HDL-cholesterol concentration but both high- and low-oleic acid ground beef decrease HDL particle diameter in normocholesterolemic men

On the basis of previous results from this laboratory, this study tested the hypothesis that ground beef high in MUFA and low in SFA would increase the HDL-cholesterol (HDL-C) concentration and LDL particle diameter. In a crossover dietary intervention, 27 free-living normocholesterolemic men completed treatments in which five 114-g ground beef patties/wk were consumed for 5 wk with an intervening 4-wk washout period. Patties contained 24% total fat with a MUFA:SFA ratio of either 0.71 (low MUFA, from pasture-fed cattle) or 1.10 (high MUFA, from grain-fed cattle). High-MUFA ground beef provided 3.21 g more 18:1(n-9), 1.26 g less 18:0, 0.89 g less 16:0, and 0.36 g less 18:1(trans) fatty acids per patty than did the low-MUFA ground beef. Both ground beef interventions decreased plasma insulin and HDL(2) and HDL(3) particle diameters and increased plasma 18:0 and 20:4(n-6) (all P ≤ 0.05) relative to baseline values. Only the high-MUFA ground beef intervention increased the HDL-C concentration from baseline (P = 0.02). The plasma TG concentration was positively correlated with the plasma insulin concentration (r = 0.40; P < 0.001) and negatively correlated with HDL-C (r = -0.47; P < 0.001) and plasma 18:0 (r = -0.24; P < 0.01). Plasma insulin and HDL diameters were not correlated (r = 0.01; P > 0.50), indicating that reductions in these measures were not coordinately regulated. The data indicate that dietary beef interventions have effects on risk factors for cardiovascular disease that are independent (insulin, HDL diameters) and dependent (HDL-C) on beef fatty acid composition.

Combination of niacin extended-release and simvastatin results in a less atherogenic lipid profile than atorvastatin monotherapy

OBJECTIVE

To compare the effects of combination niacin extended-release + simvastatin (NER/S) versus atorvastatin alone on apolipoproteins and lipid fractions in a post hoc analysis from SUPREME, a study which compared the lipid effects of niacin extended-release + simvastatin and atorvastatin in patients with hyperlipidemia or mixed dyslipidemia.

PATIENTS AND METHODS

Patients (n = 137) with dyslipidemia (not previously receiving statin therapy or having discontinued any lipid-altering treatment 4-5 weeks prior to the study) received NER/S (1000/40 mg/day for four weeks, then 2000/40 mg/day for eight weeks) or atorvastatin 40 mg/day for 12 weeks. Median percent changes in apolipoprotein (apo) A-1, apo B, and the apo B:A-I ratio, and nuclear magnetic resonance lipoprotein subclasses from baseline to week 12 were compared using the Wilcoxon rank-sum test and Fisher's exact test.

RESULTS

NER/S treatment produced significantly greater percent changes in apo A-I and apo B:A-I, and, at the final visit, apo B < 80 mg/dL was attained by 59% versus 33% of patients, compared with atorvastatin treatment (P = 0.003). NER/S treatment resulted in greater percent reductions in calculated particle numbers for low-density lipoprotein (LDL, 52% versus 43%; P = 0.022), small LDL (55% versus 45%; P = 0.011), very low-density lipoprotein (VLDL) and total chylomicrons (63% versus 39%; P < 0.001), and greater increases in particle size for LDL (2.7% versus 1.0%; P = 0.007) and VLDL (9.3% versus 0.1%; P < 0.001), compared with atorvastatin.

CONCLUSION

NER/S treatment significantly improved apo A-I levels and the apo B:A-I ratio, significantly lowered the number of atherogenic LDL particles and VLDL and chylomicron particles, and increased the mean size of LDL and VLDL particles, compared with atorvastatin.

Lipoprotein subfractions and cardiovascular disease risk

PURPOSE OF REVIEW

Subfractions of LDL and HDL defined by differences in particle size and density have been associated to varying degrees with risk of cardiovascular disease (CVD). Assessment of these relationships has been clouded by lack of standardization among the various analytic methodologies as well as the strong correlations of the subfractions with each other and with standard lipid and lipoprotein risk markers. This review summarizes the properties of the major LDL and HDL particle subclasses, and recent evidence linking their measurement with risk of atherosclerosis and CVD.

RECENT FINDINGS

Several recent studies have shown independent relationships of levels of LDL and HDL-size subclasses to risk of both coronary artery and cerebrovascular disease. However, the two largest studies, employing nuclear magnetic resonance and ion mobility, respectively, did not find evidence that these measurements improved risk assessment compared with standard lipoprotein assays. In the latter study, principal component analysis was used to group multiple subfraction measurements into three distinct and statistically independent clusters that were related both to cardiovascular outcomes and to genotypes that may reflect underlying metabolic determinants.

SUMMARY

Although there is as yet inconclusive evidence as to the extent to which LDL and HDL subfraction measurements improve clinical assessment of CVD risk beyond standard lipid risk markers, recent studies suggest that more refined analyses of lipoprotein subspecies may lead to further improvements in CVD risk evaluation and particularly in identification of appropriate targets for therapeutic intervention in individual patients.