Does simultaneous determination of LDL and HDL particle size improve prediction of coronary artery disease risk?

The role of atherogenic lipoproteins in diabetes: Molecular aspects and clinical significance

Dyslipidaemia plays a prominent role in the genesis of atherosclerotic plaque and the increased cardiovascular risk in diabetes. Macrophages readily take up atherogenic lipoproteins, transforming into foam cells and amplifying vascular damage in the presence of endothelial dysfunction. We discuss the importance of distinct lipoprotein subclasses in atherogenic diabetic dyslipidaemia as well as the effects of novel anti-diabetic agents on lipoprotein fractions and ultimately on cardiovascular risk prevention. In patients with diabetes, lipid abnormalities should be aggressively identified and treated in conjunction with therapeutical agents used to prevent cardiovascular disease. The use of drugs that improve diabetic dyslipidaemia plays a prominent role in conferring cardiovascular benefit in individuals with diabetes.

Novel Pharmaceutical and Nutraceutical-Based Approaches for Cardiovascular Diseases Prevention Targeting Atherogenic Small Dense LDL

Compelling evidence supports the causative link between increased levels of low-density lipoprotein cholesterol (LDL-C) and atherosclerotic cardiovascular disease (CVD) development. For that reason, the principal aim of primary and secondary cardiovascular prevention is to reach and sustain recommended LDL-C goals. Although there is a considerable body of evidence that shows that lowering LDL-C levels is directly associated with CVD risk reduction, recent data shows that the majority of patients across Europe cannot achieve their LDL-C targets. In attempting to address this matter, a new overarching concept of a lipid-lowering approach, comprising of even more intensive, much earlier and longer intervention to reduce LDL-C level, was recently proposed for high-risk patients. Another important concern is the residual risk for recurrent cardiovascular events despite optimal LDL-C reduction, suggesting that novel lipid biomarkers should also be considered as potential therapeutic targets. Among them, small dense LDL particles (sdLDL) seem to have the most significant potential for therapeutic modulation. This paper discusses the potential of traditional and emerging lipid-lowering approaches for cardiovascular prevention by targeting sdLDL particles.

A New Look at Novel Cardiovascular Risk Biomarkers: The Role of Atherogenic Lipoproteins and Innovative Antidiabetic Therapies

The presence of residual cardiovascular disease (CVD) risk is a current dilemma in clinical practice; indeed, despite optimal management and treatment, a considerable proportion of patients still undergo major CV events. Novel lipoprotein biomarkers are suggested as possible targets for improving the outcomes of patients at higher risk for CVD, and their impact on major CV events and mortality have previously been investigated. Innovative antidiabetic therapies have recently shown a significant reduction in atherogenic lipoproteins, beyond their effects on glucose parameters; it has also been suggested that such anti-atherogenic effect may represent a valuable mechanistic explanation for the cardiovascular benefit of, at least, some of the novel antidiabetic agents, such as glucagon-like peptide-1 receptor agonists. This emphasizes the need for further research in the field in order to clearly assess the effects of innovative treatments on different novel biomarkers, including atherogenic lipoproteins, such as small dense low-density lipoprotein (LDL), lipoprotein(a) (Lp(a)) and dysfunctional high-density lipoprotein (HDL). The current article discusses the clinical importance of novel lipid biomarkers for better management of patients in order to overcome residual cardiovascular risk.

Biomarkers of vitamin D status in healthy adults: Associations with serum lipid parameters: A pilot study

Vitamin D deficiency is among important healthcare challenges today. Traditionally, vitamin D status is assessed through determination of 25-hydroxy metabolite (25(OH)D), but novel data point to 24,25(OH)2D and 25(OH)D/24,25(OH)2D ratio (VDMR) as promising biomarkers. It is widely accepted that the biological role of vitamin D exceeds its well-known contribution to bone turnover. However, its effects on overall energy metabolism and lipid status alterations are not completely understood. In this study, we analyzed the relationship of vitamin D status assessed as concentrations of 25(OH)D3 and 24,25(OH)2D3 determined by liquid chromatography-tandem mass spectrometry, as well as VDMR with advanced lipid status parameters. Vitamin D status biomarkers, routine parameters of lipid status and size and distribution of lipoprotein subclasses were determined in 89 healthy adults (35 with adequate vitamin D status and 54 with vitamin D deficiency). Our results indicated a preponderance of proatherogenic small, dense LDL particles (sdLDL) in vitamin D deficient subjects. Both 25(OH)D and 24,25(OH)2D were associated with a relative proportion of sdLDL (B: -0.410; SE: 0.154; P=0.010; and B: -2.041; SE: 0.969; P=0.039, respectively). Positive correlation was found for VDMR and relative proportion of HDL 3a particles (r=0.251; P=0.024). VDMR value was decreased in subjects with vitamin D deficiency (P=0.001), thus implying its usefulness as a biomarker. A thorough investigation of novel vitamin D biomarkers and advanced lipid status parameters can be useful in the estimation of individual risk for the development of cardiometabolic alterations.

Revealing the Role of High-Density Lipoprotein in Colorectal Cancer

Colorectal cancer (CRC) is a highly prevalent malignancy with multifactorial etiology, which includes metabolic alterations as contributors to disease development. Studies have shown that lipid status disorders are involved in colorectal carcinogenesis. In line with this, previous studies have also suggested that the serum high-density lipoprotein cholesterol (HDL-C) level decreases in patients with CRC, but more recently, the focus of investigations has shifted toward the exploration of qualitative properties of HDL in this malignancy. Herein, a comprehensive overview of available evidences regarding the putative role of HDL in CRC will be presented. We will analyze existing findings regarding alterations of HDL-C levels but also HDL particle structure and distribution in CRC. In addition, changes in HDL functionality in this malignancy will be discussed. Moreover, we will focus on the genetic regulation of HDL metabolism, as well as the involvement of HDL in disturbances of cholesterol trafficking in CRC. Finally, possible therapeutic implications related to HDL will be presented. Given the available evidence, future studies are needed to resolve all raised issues concerning the suggested protective role of HDL in CRC, its presumed function as a biomarker, and eventual therapeutic approaches based on HDL.

Association of small, dense LDL-cholesterol concentration and lipoprotein particle characteristics with coronary heart disease: A systematic review and meta-analysis

OBJECTIVES

The aim of this study was to systematically collate and appraise the available evidence regarding the associations between small, dense low-density lipoprotein (sdLDL) and incident coronary heart disease (CHD), focusing on cholesterol concentration (sdLDL-C) and sdLDL particle characteristics (presence, density, and size).

BACKGROUND

Coronary heart disease (CHD) is the leading cause of death worldwide. Small, dense low-density lipoprotein (sdLDL) has been hypothesized to induce atherosclerosis and subsequent coronary heart disease (CHD). However, the etiological relevance of lipoprotein particle size (sdLDL) versus cholesterol content (sdLDL-C) remains unclear.

METHODS

PubMed, MEDLINE, Web of Science, and EMBASE were systematically searched for studies published before February 2020. CHD associations were based on quartile comparisons in eight studies of sdLDL-C and were based on binary categorization in fourteen studies of sdLDL particle size. Reported hazards ratios (HR) and odds ratios (OR) with 95% confidence interval (CI) were standardized and pooled using a random-effects meta-analysis model.

RESULTS

Data were collated from 21 studies with a total of 30,628 subjects and 5,693 incident CHD events. The average age was 67 years, and 53% were men. Higher sdLDL and sdLDL-C levels were both significantly associated with higher risk of CHD. The pooled estimate for the high vs. low categorization of sdLDL was 1.36 (95% CI: 1.21, 1.52) and 1.07 (95% CI: 1.01, 1.12) for comparing the top quartiles versus the bottom of sdLDL-C. Several studies suggested a dose response relationship.

CONCLUSIONS

The findings show a positive association between sdLDL or sdLDL-C levels and CHD, which is supported by an increasing body of genetic evidence in favor of its causality as an etiological risk factor. Thus, the results support sdLDL and sdLDL-C as a risk marker, but further research is required to establish sdLDL or sdLDL-C as a potential therapeutic marker for incident CHD risk reduction.

Paraoxonase 1 and atherosclerosis-related diseases

A direct and an indirect relationship between paraoxonase 1 (PON1) and atherosclerosis exists. Given PON1's physical location within high-density lipoprotein (HDL) particles and its recognized enzyme activity, it is certainly reasonable to suggest that PON1 facilitates the antiatherogenic nature of HDL particles. PON1 also plays a role in regulating reverse cholesterol transport, antioxidative, anti-inflammatory, antiapoptotic, vasodilative, and antithrombotic activities and several endothelial cell functions. HDL dysfunctionality is a more recent issue and seems to be centered on pathological conditions affecting HDL structure and size profiles. This review is focused on the role of PON1 status in different atherosclerosis-related diseases that we have studied over the last twenty years (coronary heart disease, acute ischemic stroke, diabetes mellitus type 2, end-stage renal disease, chronic obstructive pulmonary disease, and sarcoidosis) with the aim to determine the true value of PON1 as a biomarker. The role of PON1 in cancer is also covered, as risk factors and mechanisms underlying both atherosclerosis and cancer share common features.

A comparison of fractional flow reserve determination and coronary angiography results in patients with unstable angina and analysis of related factors

BACKGROUND

Coronary angiography (CAG) and fractional flow reserve (FFR) are currently used to identify the lesions and guide the treatment of unstable angina (UA) patients. This study aims to compare the two methods and investigate factors affecting FFR value.

METHODS

A total of 284 UA patients (296 coronary artery lesions) were enrolled from the Emergency Department of Anzhen Hospital Affiliated to Capital Medical University from January 2017 to December 2017. CAG and FFR determination were performed in all patients, and the roles of these two methods in guiding the treatment of UA were compared and analyzed. The subjects were divided into FFR ≤0.8 group and FFR >0.8 group. The general data and laboratory findings were compared between these two groups, and the possible influential factors were analyzed. The statistical analysis of t-test or chi square test was done with SPSS 20.0 software.

RESULTS

Of 296 UA lesions, 160 (54.1%) had ≥75% angiographic stenosis and 136 (45.9%) had <75% angiographic stenosis; 168 (56.8%) had an FFR value of ≤0.8 and 128 (43.2%) had an FFR value >0.8. There was no significant difference between these two examination methods (P=0.508, χ2=0.438). Further analysis showed that 43 (26.9%) of the 160 lesions with ≥75% stenosis had an FFR value of >0.8 and did not require PCI; 49 (38.3%) of the 128 lesions with 50-70% stenosis had an FFR value of ≤0.8 and needed PCI; 2 of 8 patients with <50% stenosis had an FFR value of ≤0.8 and needed PCI. If FFR was used as the "gold standard" of PCI, the sensitivity, specificity, positive predictive value, and negative predictive value of CAG in guiding PCI for UA were 69.6%, 66.4%, 73.1%, and 62.5%, respectively. Multivariate analysis with Logistic regression revealed low high-density lipoprotein (HDL) and hypertension were independent risk factors of FFR <0.8 in UA patients.

CONCLUSIONS

CAG and FFR readings could be different. A combination of CAG and FFR may help to achieve more accurate and tailored treatment of UA. The history of hypertension is an independent risk factor for FFR in UA patients, and HDL is an independent protective factor.

Can non-cholesterol sterols and lipoprotein subclasses distribution predict different patterns of cholesterol metabolism and statin therapy response?

BACKGROUND

Cholesterol homeostasis disorders may cause dyslipidemia, atherosclerosis progression and coronary artery disease (CAD) development. Evaluation of non-cholesterol sterols (NCSs) as synthesis and absorption markers, and lipoprotein particles quality may indicate the dyslipidemia early development. This study investigates associations of different cholesterol homeostasis patterns with low-density (LDL) and high-density lipoproteins (HDL) subclasses distribution in statin-treated and statin-untreated CAD patients, and potential use of aforementioned markers for CAD treatment optimization.

METHODS

The study included 78 CAD patients (47 statin-untreated and 31 statin-treated) and 31 controls (CG). NCSs concentrations were quantified using gas chromatography- flame ionization detection (GC-FID). Lipoprotein subclasses were separated by gradient gel electrophoresis.

RESULTS

In patients, cholesterol-synthesis markers were significantly higher comparing to CG. Cholesterol-synthesis markers were inversely associated with LDL size in all groups. For cholesterol homeostasis estimation, each group was divided to good and/or poor synthetizers and/or absorbers according to desmosterol and β-sitosterol median values. In CG, participants with reduced cholesterol absorption, the relative proportion of small, dense LDL was higher in those with increased cholesterol synthesis compared to those with reduced synthesis (p<0.01). LDL I fraction was significantly higher in poor synthetizers/poor absorbers subgroup compared to poor synthetizers/good absorbers (p<0.01), and good synthetizers/poor absorbers (p<0.01). Statin-treated patients with increased cholesterol absorption had increased proportion of LDL IVB (p<0.05).

CONCLUSIONS

The results suggest the existence of different lipoprotein abnormalities according to various patterns of cholesterol homeostasis. Desmosterol/β-sitosterol ratio could be used for estimating individual propensity toward dyslipidemia development and direct the future treatment.

Relapsing-remitting multiple sclerosis patients display an altered lipoprotein profile with dysfunctional HDL

Lipoproteins modulate innate and adaptive immune responses. In the chronic inflammatory disease multiple sclerosis (MS), reports on lipoprotein level alterations are inconsistent and it is unclear whether lipoprotein function is affected. Using nuclear magnetic resonance (NMR) spectroscopy, we analysed the lipoprotein profile of relapsing-remitting (RR) MS patients, progressive MS patients and healthy controls (HC). We observed smaller LDL in RRMS patients compared to healthy controls and to progressive MS patients. Furthermore, low-BMI (BMI ≤ 23 kg/m²) RRMS patients show increased levels of small HDL (sHDL), accompanied by larger, triglyceride (TG)-rich VLDL, and a higher lipoprotein insulin resistance (LP-IR) index. These alterations coincide with a reduced serum capacity to accept cholesterol via ATP-binding cassette (ABC) transporter G1, an impaired ability of HDL₃ to suppress inflammatory activity of human monocytes, and modifications of HDL₃’s main protein component ApoA-I. In summary, lipoprotein levels and function are altered in RRMS patients, especially in low-BMI patients, which may contribute to disease progression in these patients.

The Pleiotropic Effects of Atorvastatin on Stable Angina Patients: Evidence by Analysis of High-Density Lipoprotein Size and Subclasses, and Plasma mRNA

BACKGROUND

High-density lipoproteins (HDL) have athero-protective biological properties: antioxidative, anti-apoptotic, anti-inflammatory, and they have the efflux capacity of cellular cholesterol. Plasma mRNA analysis can be used to investigate statin pleiotropy in vivo as a new analytical tool for non-invasive assessment of gene expression in vascular beds. The aim of this study was to assess the pleiotropic effects of atorvastatin in stable angina patients with high-risk values (group A) as compared with patients who had borderline and desirable HDL-cholesterol (HDL-C) values (group B).

METHODS

The atorvastatin therapy (20 mg/day) was given to forty-three patients with stable angina for 10 weeks. We investigated three statin pleiotropy-targeted genes: inter-cellular adhesion molecule-1, chemokine (C-C motif) ligand 2 and cathepsin S and assessed by gel electrophoresis gradient the effects of atorvastatin on HDL size and subclasses.

RESULTS

In group A, after therapy, HDL-C concentration was significantly increased but not in group B. Atorvastatin lowered plasma chemokine (C-C motif) ligand 2 and intercellular adhesion molecule-1 mRNA levels in both groups, but did not change the plasma cathepsin S mRNA levels. In group A only, baseline total bilirubin showed negative correlations with the genes of cathepsin S (r=-0.506; p=0.023) and significantly increased after therapy.

CONCLUSIONS

HDL-C and bilirubin can be promising therapeutic targets in the treatment of cardiovascular diseases. Analysis of cell-free mRNA in plasma might become a useful tool for estimating statin pleiotropy.

Correlation between serum levels of small, dense low-density lipoprotein cholesterol and carotid stenosis in cerebral infarction patients >65 years of age

BACKGROUND

We studied the relationship between serum levels of small, dense low-density lipoprotein cholesterol (sdLDL-C) and carotid stenosis in elderly patients with ischemic cerebral infarction.

METHODS

All patients >65 years of age with newly diagnosed ischemic cerebral infarction were enrolled. None received statins before enrollment. Patients were examined for carotid stenosis by ultrasound color Doppler, and serum sdLDL-C levels were measured using an automated method.

RESULTS

The 149 patients were distributed according to their carotid stenosis as without (n = 61) or with mild (n = 30), moderate (n = 34), or severe (n = 24) carotid stenosis. sdLDL-C levels increased significantly with increasing stenosis severity (0.54 ± 0.19, 0.71 ± 0.18, 0.98 ± 0.19, and 1.32 ± 0.17 mmol/L, respectively). Spearman rank correlation analysis revealed that sdLDL-C levels and degree of carotid stenosis were positively correlated (r = 0.411; P < 0.001). Male sex, body mass index, diabetes, hypertension, hyperlipidemia, drinking, smoking, and sdLDL-C levels were positively correlated with carotid stenosis. Logistic regression analysis revealed that sdLDL-C levels are an independent risk factor of carotid stenosis (P = 0.041).

CONCLUSIONS

sdLDL-C levels are positively correlated with the severity of carotid stenosis, and are an independent risk factor in elderly patients with ischemic cerebral infarction.

Changes in LDL and HDL subclasses in normal pregnancy and associations with birth weight, birth length and head circumference

Pregnancy is associated with alterations in low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subclasses, but the exact pattern of these variations remains controversial. This study investigates longitudinal changes of plasma LDL and HDL particles distributions during the course of normal pregnancy, as well as associations of maternal LDL and HDL subclasses distributions before delivery with parameters of newborn size. Blood samples were collected from 41 healthy pregnant women throughout entire pregnancy, before delivery and 7 weeks postpartum. LDL and HDL subclasses were determined by gradient gel electrophoresis, while other biochemical parameters were measured by standard laboratory methods. During gestation LDL size significantly decreased (P < 0.001), due to reduction in relative proportion of LDL I (P < 0.01) and increase of LDL II (P < 0.001) and IIIA (P < 0.05) subclasses. In the same time, HDL size and proportions of HDL 2a particles significantly decreased (P < 0.001), with concomitant increase of HDL 3b and 3c subclasses (P < 0.05). Observed alterations were associated with changes in serum triglyceride levels. Rearrangement in LDL subclasses distribution during gestation was transient, while postpartum HDL subclasses distribution remained shifted toward smaller particles. Higher proportion of LDL IVB in maternal plasma before delivery was an independent predictor of smaller birth weights and lengths, while higher proportions of LDL IVB and HDL 2a subclasses were independent determinants of newborns' smaller head circumferences. Routine gestational and prenatal care in otherwise normal pregnancy could be complemented with evaluation of LDL and HDL particles distribution in order to ensure an adequate size of the newborn.

Smaller HDL particles are associated with absence of obstructive coronary artery disease in stable angina pectoris patients

Background

A research on novel cardiovascular risk factors is mainly focused on patients with clinically verified coronary artery disease (CAD), while less is known about their presence in symptomatic patients, but without angiographically proven occlusion of coronary arteries. The aim of this study was to compare plasma low-density lipoprotein (LDL) and high-density lipoprotein (HDL) size and subclasses in stable angina patients with and without significant obstructive CAD.

Methods

LDL and HDL subclasses were analysed in 100 stable angina patients with ≥50% of obstruction and 40 patients with less than 50% of luminal narrowing, as assessed by coronary angiography.

Results

Patients with <50% of obstruction had reduced mean HDL size and higher proportion of small HDL particles ( P < 0.05). HDL size and proportion of small HDL particles were significant and independent predictors of obstructive CAD ( P < 0.05, respectively).

Conclusions

Stable angina patients with <50% of coronary obstruction have more favourable HDL subclasses distribution than patients with significant coronary stenosis.

Clustering by plasma lipoprotein profile reveals two distinct subgroups with positive lipid response to fenofibrate therapy

Fibrates lower triglycerides and raise HDL cholesterol in dyslipidemic patients, but show heterogeneous treatment response. We used k-means clustering to identify three representative NMR lipoprotein profiles for 775 subjects from the GOLDN population, and study the response to fenofibrate in corresponding subgroups. The subjects in each subgroup showed differences in conventional lipid characteristics and in presence/absence of cardiovascular risk factors at baseline; there were subgroups with a low, medium and high degree of dyslipidemia. Modeling analysis suggests that the difference between the subgroups with low and medium dyslipidemia is influenced mainly by hepatic uptake dysfunction, while the difference between subgroups with medium and high dyslipidemia is influenced mainly by extrahepatic lipolysis disfunction. The medium and high dyslipidemia subgroups showed a positive, yet distinct lipid response to fenofibrate treatment. When comparing our subgroups to known subgrouping methods, we identified an additional 33% of the population with favorable lipid response to fenofibrate compared to a standard baseline triglyceride cutoff method. Compared to a standard HDL cholesterol cutoff method, the addition was 18%. In conclusion, by using constructing subgroups based on representative lipoprotein profiles, we have identified two subgroups of subjects with positive lipid response to fenofibrate therapy and with different underlying disturbances in lipoprotein metabolism. The total subgroup with positive lipid response to fenofibrate is larger than subgroups identified with baseline triglyceride and HDL cholesterol cutoffs.

Characteristics of low-density and high-density lipoprotein subclasses in pediatric renal transplant recipients

Renal transplant recipients often suffer from dyslipidemia which is one of the principal risk factors for cardiovascular disease. This study sought to determine characteristics of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) particles and their associations with carotid intima-media thickness (cIMT) in a group of pediatric renal transplant recipients. We also examined the influence of immunosuppressive therapy on measured LDL and HDL particle characteristics. HDL size and subclass distribution were determined using gradient gel electrophoresis, while concentrations of small, dense LDL (sdLDL)-cholesterol (sdLDL-C) and sdLDL-apolipoprotein B (sdLDL-apoB) using heparin-magnesium precipitation method in 21 renal transplant recipients and 32 controls. Renal transplant recipients had less HDL 2b (P < 0.001), but more HDL 3a (P < 0.01) and 3b (P < 0.001) subclasses. They also had increased sdLDL-C (P < 0.01) and sdLDL-apoB (P < 0.05) levels. The proportion of the HDL 3b subclasses was a significant predictor of increased cIMT (P < 0.05). Patients treated with cyclosporine had significantly higher sdLDL-C and sdLDL-apoB concentrations (P < 0.05) when compared with those on tacrolimus therapy. Pediatric renal transplant recipients have impaired distribution of HDL and LDL particles. Changes in the proportion of small-sized HDL particles are significantly associated with cIMT. Advanced lipid testing might be useful in evaluating the effects of immunosuppressive therapy.

Cox proportional hazard model analysis of survival in end-stage renal disease patients with small-sized high-density lipoprotein particles

OBJECTIVE

Dyslipidemia is commonly seen in patients with end-stage renal disease (ESRD). This prospective study investigates whether small-sized high-density lipoprotein (HDL) particles alone or in combination with high sensitivity C-reactive protein (hsCRP) are independent determinants of ESRD mortality.

DESIGN AND METHODS

We performed 36 months follow-up study in 122 haemodialysis (HD) patients. HDL size and subclass distribution were determined by gradient gel electrophoresis. Baseline characteristics of the patients were evaluated for the prediction of mortality.

RESULTS

Cox regressions analysis showed that patients with small-sized HDL particles had 2.8-fold higher risk of lethal outcome (P<0.05). Concomitant presence of small-sized HDL particles and increased hsCRP concentration were significantly associated with reduced survival rate (HR=3.907; P<0.05). Observed relationships persisted after adjustment for serum lipid and lipoprotein concentrations.

CONCLUSIONS

Our results indicate that small-sized HDL particles alone and combined with elevated hsCRP concentrations are independent predictors of reduced survival in HD patients.

Effects of rosiglitazone on fasting and postprandial low- and high-density lipoproteins size and subclasses in type 2 diabetes

Rosiglitazone may increase cardiovascular risk in patients with type 2 diabetes. Yet, its effects on atherogenic dyslipidemia are still not fully elucidated. In a prospective open-label study rosiglitazone (4 mg/day for 12 weeks) was added to a maximum of 2 oral antidiabetic drugs in 18 diabetic patients. We evaluated the effects on plasma lipids before and after an oral fat load. The size and subclasses of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) were also determined (by gradient gel electrophoresis). Rosiglitazone improved glycosylated hemoglobin ([HbA1c] P = .0023), without significant effects on fasting and postprandial plasma lipids. Fasting LDL size increased (+1.4%, P = .034), with less small, dense LDL-IIIA (-25.1%, P = .018). Postprandially, larger HDL-2b reduced (-8.7%, P = .006) and smaller HDL-3b increased (+12.2%, P = .05), without any effects on HDL size. Rosiglitazone led to antiatherogenic changes in LDL size and subclasses, with proatherogenic changes in HDL subclasses, despite no effects on plasma lipids. Their clinical relevance remains to be established.

Optimal cutoff value of high-density lipoprotein cholesterol for predicting coronary artery disease in Taiwanese population

The aim of this study was to determine if an optimal cutoff value for high-density lipoprotein cholesterol (HDL-C) can be obtained for predicting the risk of coronary artery disease (CAD) in Taiwanese population. We conducted a hospital-based case-control study. Patients identified by cardiac catheterization as having at least 70% stenosis of one major coronary artery and without diabetes were assigned to the case group (n = 184). The control group (n = 516) was composed of healthy individuals with normal blood biochemical values. The multiple logistic regression analysis was used to evaluate linear association between low-density lipoprotein cholesterol (LDL-C), HDL-C, or LDL-C/HDL-C ratio and CAD while adjusting for confounders. Furthermore, receiver operating characteristic curve analyses were constructed. Individuals with an HDL-C value less than or equal to 60 mg/dL had the significantly highest odds ratio (7.72; 95% confidence interval, 2.70-22.07) after adjusting for LDL-C, LDL-C/HDL-C ratio, and other potential confounders. The areas under the curves were 0.85 and 0.61 for HDL-C and LDL-C, respectively. The optimal cutoff value of HDL-C for predicting the presence of CAD was 46 mg/dL. Sensitivity and specificity using this cutoff value were 71.74% and 81.40%, respectively. Our findings suggest that subjects with lower levels of HDL-C have a much higher risk of CAD than those with higher levels of LDL-C. The optimal cutoff value for HDL-C in predicting the risk of CAD is considered as 46 mg/dL in the Taiwanese population.

LDL and HDL subclasses in acute ischemic stroke: prediction of risk and short-term mortality

OBJECTIVE

Small, dense low-density lipoprotein (sdLDL) and small-sized high-density lipoprotein (HDL) particles are established risk factors for ischemic heart disease. However, their clinical significance for acute ischemic stroke (AIS) is uncertain. This study evaluates associations of LDL and HDL particle sizes and subclasses with AIS risk and short-term mortality after AIS.

METHODS

Two hundred AIS patients hospitalised for first-in-a-lifetime stroke and 162 apparently healthy controls were included in the study. LDL and HDL particles were separated by gradient gel electrophoresis and serum lipid parameters were measured by standard laboratory methods. Baseline characteristics of LDL and HDL particles were evaluated for the prediction of AIS and short-term mortality after AIS.

RESULTS

AIS patients had significantly more LDL III and IVb, but less LDL I and II particles. They also had significantly smaller HDL size, more HDL 3a, 3b and 3c and less HDL 2b subclasses. The relative content of both sdLDL and small-sized HDL particles was significantly increased in patients (P<0.001 and P<0.001, respectively). In addition, sdLDL was significantly higher in AIS fatalities (n=25) compared with survivors (n=175, P<0.05). Increased sdLDL was a significant predictor of AIS (OR=4.31; P<0.001) and in-hospital mortality after AIS (OR=5.50; P<0.05). The observed relationships persisted after adjustment for conventional risk factors.

CONCLUSIONS

AIS is associated with adverse distributions of LDL and HDL subclasses. In addition, short-term mortality after AIS is associated with increased sdLDL particles. Our results indicate that sdLDL is an independent predictor of both AIS onset and consecutive short-term mortality.

Combined effects of small apolipoprotein (a) isoforms and small, dense LDL on coronary artery disease risk

BACKGROUND AND AIMS

Lipoprotein (a) [Lp(a)] consists of low-density lipoprotein (LDL) and apolipoprotein (a) [apo(a)]. Both Lp(a) constituents are well-recognized risk factors for coronary artery disease (CAD). This study investigates the interrelationship of apo(a) and LDL size, as well as their possible synergistic effect on the increase of CAD risk.

METHODS

One hundred nine CAD patients and 102 apparently healthy subjects were included in the study. Lp(a) concentration was measured using immunoturbidimetry. The sizes of apo(a) isoforms were determined by SDS-agarose gel electrophoresis followed by immunoblotting. LDL particle size was determined by gradient gel electrophoresis.

RESULTS

We found an inverse correlation between apo(a) size and Lp(a) concentration (r(2) = 31%, p <0.001 in the control group and r(2) = 35%, p <0.001 in the CAD group). Individuals with smaller apo(a) isoforms and small, dense LDL (sdLDL) >50% had the highest risk of CAD development (OR = 4.23, p = 0.017). The synergy index (SIM) for the combination of smaller apo(a) isoforms and sdLDL >50% was 1.2. Adjustment for Lp(a) and triacylglycerol concentrations eliminated smaller apo(a)/sdLDL >50% related risk (p = 0.233 and p = 0.09, respectively).

CONCLUSIONS

Smaller apo(a) isoforms appear to be superior to sdLDL for the assessment of CAD risk. Their combined effect is synergistic.

High serum uric acid and low-grade inflammation are associated with smaller LDL and HDL particles

Elevated serum uric acid (UA) is associated with higher risk for cardiovascular disease (CVD). Smaller, denser low density lipoprotein (LDL) and high-density lipoprotein (HDL) particles are the potential risk factors for CVD, while the role and diagnostic value of inflammatory markers are firmly established. This current cross-sectional study investigates interrelationships between UA, high sensitivity C-reactive protein (hsCRP) and fibrinogen concentrations with LDL and HDL sizes in healthy middle-aged subjects. The outcomes-of-interest were smaller, denser LDL and HDL particles (LDL size <or=25.5nm and HDL size <or=8.8nm). Serum UA, hsCRP and plasma fibrinogen concentrations were measured by standard laboratory methods in a sample of 194 healthy volunteers (112 men and 82 women). LDL and HDL particle sizes were determined by gradient gel electrophoresis. The subjects in the highest UA tertile had significantly smaller LDL and HDL particle sizes (P<0.05 and P<0.01, respectively) and higher concentrations of fibrinogen and hsCRP (P<0.05 and P<0.01, respectively). Elevated UA (>or=318micromol/L) was a significant predictor of smaller, denser LDL and HDL particles (OR=3.09; P<0.01; n=19 and OR=4.40; P<0.001; n=23, respectively). The observed relationship with smaller HDL size persisted after adjustment for conventional cardiovascular risk factors. UA strongly correlated with both markers of inflammation. In addition, the higher hsCRP level correlated with smaller LDL size (P<0.05), while fibrinogen concentration was inversely related to HDL size (P<0.05). Multiple regression analysis revealed that HDL size and inflammatory markers remained independent determinants of UA concentration. In conclusion, higher serum UA and low-grade inflammation are closely linked to alterations in lipoprotein metabolism which may represent an early sign of atherosclerosis in asymptomatic subjects.