Low-density lipoprotein and oxidised low-density lipoprotein: their role in the development of atherosclerosis

The association of the apolipoprotein B/A1 ratio and the metabolic syndrome in children and adolescents: a systematic review and meta-analysis

Objectives

Metabolic syndrome (MetS) is a constellation of coexisting cardiovascular risk factors. This study aimed to assess the evidence for the association between the apolipoprotein B/A1 ratio, apolipoprotein B, and apolipoprotein A1, and the MetS in children and adolescents.

Methods

The English electronic databases including PubMed, Embase, Web of Science, and Scopus were searched up to February 28, 2022. To ascertain the validity of eligible studies, modified JBI scale was used. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were pooled using the random-effects model to evaluate the association between the apolipoprotein B/A1 ratio, apolipoprotein B, and apolipoprotein A1 and the MetS. Heterogeneity amongst the studies was determined by the use of the Galbraith diagram, Cochran's Q-test, and I2 test. Publication bias was assessed using Egger's and Begg's tests.

Results

From 7356 records, 5 studies were included in the meta-analysis, representing a total number of 232 participants with MetS and 1320 participants as control group. The results indicated that increased levels of apolipoprotein B/A1 ratio (SMD 1.26; 95% CI: 1.04, 1.47) and apolipoprotein B (SMD 0.75; 95% CI: 0.36, 1.14) and decreased levels of apolipoprotein A1 (SMD -0.53; 95% CI: -0.69, -0.37) are linked to the presence of MetS. The notable findings were, children and adolescents with MetS had elevated levels of the apolipoprotein B/A1 ratio, apolipoprotein B, and decreased levels of apolipoprotein A1.

Conclusions

Our results suggest the need to evaluate the levels of apolipoproteins for detecting the risk of MetS in children and adolescents.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01235-z.

Multiomics Analyses Reveal That Long-Term Intake of Hesperetin-7-O-glucoside Modulates the Gut Microbiota and Bile Acid Metabolism in Mice

Hesperetin-7-O-glucoside (Hes-7-G) is a typical flavonoid monoglucoside, which can be generated from hesperidin with the removal of rhamnose by hydrolysis. Untargeted and targeted metabolomics together with 16S rRNA gene sequencing were employed to explore the exact absorption site of Hes-7-G and its beneficial effect in mice. Intestinal ¹H nuclear magnetic resonance (NMR)-based metabolomics screening showed that Hes-7-G is mainly metabolized in the small intestine of mice, especially the ileum segment. Quantification analysis of bile acids (BAs) in the liver, intestinal tract, feces, and serum of mice suggests that Hes-7-G intake accelerates the processes of biosynthesis and excretion of BAs, thus promoting digestion and lowing hepatic cholesterol and triglyceride. 16S rRNA gene sequencing reveals that Hes-7-G significantly elevates the diversity of the gut microbiota in mice, especially those bacteria associated with BA secondary metabolism. These results demonstrated that long-term dietary Hes-7-G plays beneficial roles in health by modulating the gut bacteria and BA metabolism in mice.

ROS responsive nanoparticles loaded with lipid-specific AIEgen for atherosclerosis-targeted diagnosis and bifunctional therapy

Atherosclerosis, which is triggered by endothelial damage, progressive local inflammation and excessive lipid accumulation, is one of the most common cardiovascular diseases in recent years. Drug delivery systems have shown great potential for the accurate diagnosis and effective treatment of early atherosclerosis, but are accompanied by disadvantages such as poor stability, lack of active targeting and non-specific recognition capabilities, which still need to be further developed. In our work, a multifunctional nanoparticle (LFP/PCDPD) with reactive oxygen species (ROS) responsive drug release, lipid removal, and lipid-specific AIE fluorescence imaging was constructed. Cyclodextrin structure with lipid removal function and PMEMA blocks with ROS-response-mediated hydrophobic to hydrophilic conversion were simultaneously introduced into the structure of LFP/PCDPD to load the anti-inflammatory drug prednisolone (Pred) and lipid-specific AIEgen (LFP). The active targeting function of LFP/PCDPD was conferred by the high affinity of dextran to the vascular adhesion molecule-1 (VCAM-1) and CD44 receptor on the surface of broken endothelial cells. After intravenous injection into ApoE^-/- mice, LFP/PCDPD actively enriched in the microenvironment of local ROS overexpression and rich lipids in atherosclerosis. Pred and LFP were released while lipids were removed, thus enabling proactive targeting of atherosclerosis and efficient "two-pronged" treatment.

Serum apolipoprotein B/apolipoprotein A1 ratio in relation to intervertebral disk herniation: a cross-sectional frequency-matched case-control study

Study design

This was a cross-sectional frequency-matched case–control study.

Background and aim

The serum lipid profile of lipoprotein(a) [Lp(a)] level and apolipoprotein B/apolipoprotein A1 ratio (Apo B/Apo A1) ratio were found to be more representative for serum lipid level and were recognized as the independent risk factors for various diseases. Although the blood levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were found to be associated with symptomatic intervertebral disk herniation (IDH), no studies to date have evaluated the association of Apo AI, Apo B, Lp(a), and Apo B/Apo AI levels with symptomatic IDH. This study aimed to assess the link between blood lipid levels and symptomatic IDH.

Method

The study included 1839 Chinese patients. Of these, 918 patients were diagnosed with IDH and enrolled in the experimental group. A control group of 921 patients underwent a physical examination during the same period. The serum lipid levels of TC, TG, LDL-C, HDL-C, Lp(a), Apo B, and Apo B/Apo AI were examined and analyzed. The control group comprised randomly selected patients who met the baseline levels of the aforementioned lipid molecules.

Results

Patients with IDH exhibited significantly higher TC, TG, LDL, Apo B, and Lp(a) levels than controls. The percentage of high TC, high TG, high LDL, high Apo B, and high Lp(a) were obviously higher in the IDH group than in the control group. However, hyperlipidemia had no relationship with the degenerated segment of the IDH (P = 0.201). The odds ratio (OR) for the incidence of IDH with elevated levels of LDL-C, TC, TG, Lp(a), Apo B, and Apo B/Apo AI was 1.583, 1.74, 1.62, 1.58, 1.49, and 1.39, respectively. The correlation analysis revealed the correlation between elevated LDL-C, TC, TG, Apo B, Lp(a), and incidence of IDH was significant (R²_LDL = 0.017; R²_TC = 0.004; R²_TG = 0.015; R²_{Apo B} = 0.004; R²_Lp(a) = 0.021) (P < 0.05).

Conclusion

This study suggested that elevated levels of serum TC, TG, LDL, Apo B, Lp(a), and Apo B/Apo AI were associated with a higher risk of IDH. This study provided useful information to identify a population that might be at risk of developing IDH based on elevated lipid levels.

Risk Factors and Their Diagnostic Values for Ocular Metastases in Gastric Adenocarcinoma

Objective

Gastric adenocarcinoma originates from the glands in the superficial layer or mucosa of the stomach. It is prone to metastases, of which ocular metastasis (OM) is rare, but once it occurs the disease is considered more serious. The aim of this study was to investigate the risk factors for OM in gastric adenocarcinoma.

Methods

Patients with gastric adenocarcinoma were recruited to this study between June 2003 and July 2019. Demographic data and serological indicators (SI) were compared between patients with and without OM, and binary logistic regression was used to explore whether the relevant SI may be risk factors for OM of gastric adenocarcinoma. Receiver operating characteristic (ROC) curves were used to analyze different SIs for OM in gastric cancer patients.

Results

Chi-square tests showed significant between-groups difference in gender composition (P < 0.05), but not in age or histological grade (P > 0.05). t-test results showed that low-density lipoprotein (LDL) and carbohydrate antigen-724 (CA724) were significantly higher in patients with than without OM (P < 0.05). Binary logistic regression analysis showed that LDL was an independent risk factor for OM (P < 0.001). ROC curve analysis showed that the areas under the curves (AUC) for LDL and CA724 were 0.903 and 0.913 respectively, with higher AUC for combined LDL and CA724 (0.934; P < 0.001).

Conclusion

LDL and CA724 have value as predictors for OM in patients with gastric adenocarcinoma, with higher predictive value when these factors are combined.

Paeonol inhibits NLRP3 mediated inflammation in rat endothelial cells by elevating hyperlipidemic rats plasma exosomal miRNA-223

Atherosclerosis (AS) is a multifactorial chronic inflammatory disease, and hyperlipidemia is the important factors leading to AS, which can cause vascular endothelial dysfunction. Paeonol (Pae) is a potential therapeutic drug for AS, and we have previously shown that Pae regulated the expression of monocytes-derived exosomal microRNA-223 (miR-223). However, the mechanisms of the anti-AS effect of Pae are still not fully understood. In this study, we aim to investigate if Pae could inhibit NLRP3 inflammasome mediated inflammation via elevating hyperlipidemic rats plasma-derived exosomal miR-223. We used high-fat-diet induced hyperlipidemic rats as model for further investigation. Rats were treated with Pae (75, 150 or 300 mg/kg) orally, and then exosomes were isolated from hyperlipidemic rat plasma by ultracentrifugation. In vivo experiments confirmed that Pae markedly reduced serum TC, TG, IL-1β, and IL-6 levels. Both CCK-8 and trypan blue staining showed that the survival rate of rat aortic endothelial cells (RAECs) in the Pae-exo group was higher than that in the model group. Also, Pae-exo dose-dependently increased the survival rate of RAECs and reduced inflammatory cytokines level (IL-1β, and IL-6). Furthermore, Pae-exo successfully increased the expression of exosomal miR-223 and relieved inflammatory secretion. Finally, decreased expression of NLRP3, ASC, caspase-1 and ICAM-1 indicated that Pae-exo attenuated inflammatory reaction of RAECs by suppressing NLRP3 signaling pathway. Altogether, our results showed that Pae inhibited the downstream NLRP3 inflammasome pathway by increasing the level of miR-223 in plasma derived exosomes of hyperlipidemic rats, providing new insights in the treatment of AS with the use of Pae.

Protective Effect of Ginkgolic Acid in Attenuating LDL Induced Inflammation Human Peripheral Blood Mononuclear Cells via Altering the NF-κB Signaling Pathway

Oxidized low-density lipoprotein (ox-LDL) is considered as the significant maker of inflammatory reaction. ox-LDL was reported to play a crucial role in the pathogenesis of atherosclerosis (AS). In the current study, we scrutinize the suppressive effect of ginkgolic acid against ox-LDL induced an oxidative and inflammatory response in human microvascular endothelial cells (HMEC-1) and human peripheral blood mononuclear cells (nPBMCs) and explore the mechanism of action. HMEC-1 cells are treated with ox-LDL in the presence of different concentration of ginkgolic acid. MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was performed for the estimation of cell viability effect. Reactive oxygen species (ROS), inflammatory cytokines, and NF-κB activity are also estimated. For the hPBMCs assay, the cells were isolated from the healthy volunteers and cultured. The cells were further divided into different group and received the ginkgolic acid. Additionally, ROS, inflammatory marker such as prostaglandin E2 (PGE2), lipoxygenase (LOX), nitric oxide (NO), cyclooxygenase (COX) protein expression, and mRNA expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and vascular cell adhesion protein 1 (VCAM-1) were estimated in the ox-LDL treated group. The result exhibited that ginkgolic acid treatment induced the cell viability boosting in ox-LDL treatment and intracellular ROS significantly decreased by ginkgolic acid. Pro-inflammatory cytokines also downregulated via ginkgolic acid. Moreover, ginkgolic acid reduced the ox-LDL-induced NF-κB. The mRNA and protein expression of TNF-α, IL-6, and VCAM-1 considerably increased in the ox-LDL treated group and ginkgolic acid significantly reduced the mRNA and protein expression. An inflammatory marker such as PGE2, LOX, and NO were increased in the ox-LDL treated group and ginkgolic acid treated group exhibited the reduction of an inflammatory marker. Based on the result, we can conclude that ginkgolic acid significantly reduced and reversed the ox-LDL-induced modulation, suggesting its anti-inflammatory effect via the NF-κB pathway.

Influence of hypercholesterolemia on serum antibodies against oxidized LDL in children and adolescents

BACKGROUND

The oxidation of low-density lipoprotein (LDL; oxLDL) appears to play a key role in the early development of atherosclerosis. Increased serum antibodies against the oxLDL (anti-oxLDL antibodies) have been found in adults with atherosclerotic disease, as well as in healthy adults. The clinical significance and its precise role (atherogenic or atheroprotective), however, have not yet been clarified. This aim of this study was therefore to evaluate anti-oxLDL antibodies in healthy children and adolescents with and without hypercholesterolemia.

METHODS

The study involved 312 subjects, aged 4-18 years, 141 with LDL cholesterol (LDL-C) ≥130 mg/dL and 171 with acceptable LDL-C (<110 mg/dL). Total anti-oxLDL antibodies, total cholesterol, LDL-C and high-density lipoprotein cholesterol, triglycerides, apolipoproteins A1 and B, lipoprotein (a) and high-sensitivity C-reactive protein were measured in fasting serum. The anti-oxLDL antibodies were measured on enzyme-linked immunosorbent assay.

RESULTS

Anti-oxLDL antibodies were similar in the hypercholesterolemia and non-hypercholesterolemia groups. Girls had significantly higher anti-oxLDL antibodies compared with boys. There was no significant correlation of antibodies with age or body mass index. Increased apolipoprotein B was an important factor for lower anti-oxLDL antibodies, while all other parameters had no significant association with anti-oxLDL antibodies.

CONCLUSION

In children and adolescents with hypercholesterolemia, total anti-oxLDL antibodies cannot serve as a marker for risk for atherosclerosis or for future cardiovascular disease.

Obesity contributes more to increasing ApoB/ApoA1 ratio than hyperandrogenism in PCOS women aged 20-38 years in China

We investigated the association between the apolipoprotein B (ApoB)/apolipoprotein A1 (ApoA1) ratio and insulin resistance (IR), metabolic syndrome (MS) and its components in Chinese polycystic ovary syndrome (PCOS) adults. We also examined whether hyperandrogenism is involved in obesity-related metabolic abnormalities in a cohort of patients. A clinical cross-sectional study consisting of 532 Chinese PCOS adults aged 20–38 years was designed. Each subject underwent a physical examination and laboratory evaluation. We found that the ApoB/ApoA1 ratio was significantly higher in patients with MS compared to those without MS. This test provided 83.6% sensitivity and 67.6% specificity with a threshold value of 0.60 in MS. The ApoB/ApoA1 ratio increased significantly as the number of MS components increased. After adjusting for age, the patients with MS or IR were more likely to be in the high ApoB/ApoA1 group, and the ApoB/ApoA1 ratio was associated significantly with each of the MS components, high free testosterone (FT), and high free androgen index (FAI). After adjusting for age and body mass index (BMI), the association persisted for all factors excluding high blood pressure (BP), high fasting plasma glucose (FPG), high FT, and high FAI. Therefore, the ApoB/ApoA1 ratio was strongly associated with IR, MS and its components, high FT, and high FAI. A high ApoB/ApoA1 ratio appears to be a good predictive marker of MS in Chinese PCOS adults. Obesity, especially central obesity, contributes more to increasing ApoB/ApoA1 ratio than increased BP, FPG, FT and FAI in this cohort of PCOS patients.

NUMERICAL MODELING OF ATHEROSCLEROSIS LESION EVOLUTION IN TIME I. INITIAL STAGE OF THE DISEASE

Atherosclerosis is one of the main causes of death in the developed world. The disease, which is an inflammatory disease, has been the focus of many studies. A few studies attempted to model atherosclerosis lesion development mathematically while no attention has been paid to the multistage nature of the disease. The present study provides a mathematical model for atherosclerosis evolution by focusing on the inflammatory responses of the initial stage of the disease. In the model, the inflammatory response in type I lesion, which includes endothelium dysfunction, LDL oxidation, monocytes entry, foam cell formation and intima property changes, are coupled with the transport equations of blood and LDL in lumen and arterial wall. The innovation of the model is determination of the duration of the initial stage of lesion propagation for a specific patient while the presence of leaky junction in endothelial layer and LDL oxidation in the intima layer are considered. The greatest advantage of the study in comparison with previous studies is to provide a model for the initiating stage of the atherosclerosis development so that a more precise result of the disease evolution is obtained.

Association of macular pigment optical density with serum concentration of oxidized low-density lipoprotein in healthy adults

PURPOSE

To analyze the association between macular pigment optical density (MPOD), which reflects lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) in the macula, and background characteristics.

METHODS

Fifty-five healthy adult volunteers were analyzed. Macular pigment optical density was measured using a heterochromatic flicker photometry technique, and serum concentrations of carotenoids and lipoproteins were by high-performance liquid chromatography and enzyme-linked immunosorbent assay, respectively. Dietary intake of nutrient was determined by a validated self-administered questionnaire on ingestion frequency.

RESULTS

Macular pigment optical density was positively correlated with serum concentrations of L and Z and dietary L intake and inversely correlated with serum oxidized low-density lipoprotein (LDL). Although MPOD decreased with age (95% confidence interval, -0.011 to -0.002; correlation coefficient, -0.269; P = 0.007), serum L/Z and dietary L intake did not. In contrast, serum oxidized LDL was positively correlated with age (95% confidence interval, 0.69-2.34; correlation coefficient, 0.333; P = 0.0004). After adjusting for age, sex, and oxidized LDL, serum L was positively correlated with MPOD (95% confidence interval, 0.88-1.69; P = 0.000001). After adjusting for age, sex, and serum L, serum oxidized LDL was inversely correlated with MPOD (95% confidence interval, -0.002 to -0.0004; P = 0.006).

CONCLUSION

Macular pigment optical density was inversely correlated with serum oxidized LDL. Further study to know the impact of oxidized LDL on MPOD may be warranted.

Kinetic modeling of low density lipoprotein oxidation in arterial wall and its application in atherosclerotic lesions prediction

Oxidation of low-density lipoprotein (LDL) is one of the major factors in atherogenic process. Trapped oxidized LDL (Ox-LDL) in the subendothelial matrix is taken up by macrophage and leads to foam cell generation creating the first step in atherosclerosis development. Many researchers have studied LDL oxidation using in vitro cell-induced LDL oxidation model. The present study provides a kinetic model for LDL oxidation in intima layer that can be used in modeling of atherosclerotic lesions development. This is accomplished by considering lipid peroxidation kinetic in LDL through a system of elementary reactions. In comparison, characteristics of our proposed kinetic model are consistent with the results of previous experimental models from other researches. Furthermore, our proposed LDL oxidation model is added to the mass transfer equation in order to predict the LDL concentration distribution in intima layer which is usually difficult to measure experimentally. According to the results, LDL oxidation kinetic constant is an important parameter that affects LDL concentration in intima layer so that existence of antioxidants that is responsible for the reduction of initiating rates and prevention of radical formations, have increased the concentration of LDL in intima by reducing the LDL oxidation rate.

Apolipoprotein B/apolipoprotein A1 ratio is a good predictive marker of metabolic syndrome and pre-metabolic syndrome in Chinese adolescent women with polycystic ovary syndrome

AIM

The apolipoprotein B/apolipoprotein A1 (ApoB/ApoA1) ratio is well known to be related to metabolic syndrome (MS) and its components in adults of different races. There is low prevalence of MS but high occurrence of various metabolic disorders in Chinese adolescent women with polycystic ovary syndrome (PCOS). We sought to assess if the ApoB/ApoA1 ratio can be used as a predictive marker of MS and pre-MS in Chinese adolescent women with PCOS.

MATERIAL AND METHODS

This cross-sectional study included 160 Chinese adolescent women. Based on International Diabetes Federation criteria for MS, patients who had no less than two components of MS but did not meet the criteria for the diagnosis of MS were considered as having pre-MS.

RESULTS

The ApoB/ApoA1 ratio was higher in obese subjects with high free androgen index (FAI). The ApoB/ApoA1 ratio increased significantly as the number of MS components increased and provided 87.5% of sensitivity and 78.9% of specificity with a threshold value of 0.63 for MS, 86.2% of sensitivity and 79.4% of specificity with a threshold value of 0.58 for pre-MS in Chinese adolescent women with PCOS.

CONCLUSION

The ApoB/ApoA1 ratio was a good predictive marker of MS and pre-MS in Chinese adolescent women with PCOS. FAI could be involved in obesity-related metabolic abnormalities.

Effect of oxidized low-density lipoprotein concentration polarization on human smooth muscle cells' proliferation, cycle, apoptosis and oxidized low-density lipoprotein uptake

To clarify the effect of concentration polarization of oxidative modification of low-density lipoproteins (ox-LDLs) on human smooth muscle cells (SMCs), the proliferation, ox-LDL uptake and apoptosis with SMCs cultured on permeable (the permeable group) or non-permeable membranes (the non-permeable group) were analysed by 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay, spectrofluorometry and flow cytometry using a parallel-plate flow chamber technique. The concentration polarization of ox-LDLs at the surface of the cultured cell monolayer was assessed by confocal laser microscopy. The results showed that concentration polarization of ox-LDLs could indeed occur at the cultured cell monolayer surface of the permeable group, leading to an enhanced wall concentration of ox-LDLs that was over 15 per cent higher than the bulk concentration of the perfusion solution at a pressure of 100 mmHg. When concentration of ox-LDLs in the perfusion solution was less than or equal to 100 µg ml(-1), SMCs' proliferation was induced, while cell apoptosis was induced when its concentration was above 150 µg ml(-1). The uptake of ox-LDLs by the cultured cells was significantly higher for the permeable group than for the non-permeable group. In addition, the ox-LDL-induced cell death and apoptosis were much more severe in the permeable group than that in the non-permeable group. Therefore, the experimental study suggests that concentration polarization of ox-LDLs plays an adverse role in the vascular system owing to its toxicity to vascular cells, in turn enhance ox-LDL infiltration into the arterial wall and accelerate SMC apoptosis.

Apolipoprotein B/A1 ratio is associated with free androgen index and visceral adiposity and may be an indicator of metabolic syndrome in male children and adolescents

OBJECTIVE

A high apolipoprotein B/apolipoprotein A1 (apoB/A1) ratio is strongly associated with cardiometabolic diseases. However, few studies have examined this ratio in children and adolescents. The aim of our study was to determine significant factors related to the apoB/A1 ratio and examine its association with paediatric metabolic syndrome.

PATIENTS AND METHODS

Sixty-seven male children and adolescents were recruited. We measured anthropometric parameters, fat areas by abdominal computed tomography, fasting glucose, insulin, lipid profiles, apoB, apoA1, adiponectin, free androgen index (FAI) and oestradiol.

RESULTS

Thirty per cent of participants (n = 20) were identified as having paediatric metabolic syndrome. The apoB/A1 ratio was significantly correlated with BMI z-score, waist circumference, waist-to-hip ratio (WHR), waist-to-height ratio, abdominal fat areas, total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, adiponectin and leptin. In addition to lipid profiles, WHR was identified as a significant independent variable correlated with the apoB/A1 ratio. Obese boys with a high FAI (>75th percentile) had significantly lower adiponectin and higher apoB/A1 ratios than those with a low FAI. The apoB/A1 ratio was higher in subjects with high visceral fat (>50th percentile) and a high FAI when compared with subjects with low visceral fat and a low FAI. The prevalence of paediatric metabolic syndrome was significantly associated with increasing tertiles of the apoB/A1 ratio (highest tertile; odds ratio = 18·8 [95% confidence interval = 1·8-198·8], P < 0·05).

CONCLUSION

ApoB/A1 ratio was significantly higher in viscerally obese male children and adolescents with high levels of FAI and was associated with increased frequency of paediatric metabolic syndrome.

Endothelial progenitor cells: novel biomarker and promising cell therapy for cardiovascular disease

Bone-marrow-derived EPCs (endothelial progenitor cells) play an integral role in the regulation and protection of the endothelium, as well as new vessel formation. Peripheral circulating EPC number and function are robust biomarkers of vascular risk for a multitude of diseases, particularly CVD (cardiovascular disease). Importantly, using EPCs as a biomarker is independent of both traditional and non-traditional risk factors (e.g. hypertension, hypercholesterolaemia and C-reactive protein), with infused ex vivo-expanded EPCs showing potential for improved endothelial function and either reducing the risk of events or enhancing recovery from ischaemia. However, as the number of existing cardiovascular risk factors is variable between patients, simple EPC counts do not adequately describe vascular disease risk in all clinical conditions and, as such, the risk of CVD remains. It is likely that this limitation is attributable to variation in the definition of EPCs, as well as a difference in the interaction between EPCs and other cells involved in vascular control such as pericytes, smooth muscle cells and macrophages. For EPCs to be used regularly in clinical practice, agreement on definitions of EPC subtypes is needed, and recognition that function of EPCs (rather than number) may be a better marker of vascular risk in certain CVD risk states. The present review focuses on the identification of measures to improve individual risk stratification and, further, to potentially individualize patient care to address specific EPC functional abnormalities. Herein, we describe that future therapeutic use of EPCs will probably rely on a combination of strategies, including optimization of the function of adjunct cell types to prime tissues for the effect of EPCs.

An improved anion-exchange high-performance liquid chromatography method for measuring oxidized form of LDLs in human plasma

Background

Circulating oxidized low-density lipoproteins (LDLs) (ox-LDLs) could be a sensitive marker to predict future cardiovascular events. However, a method to evaluate oxidized forms of LDLs systemically in human plasma is not yet established. In this study, we developed a novel and convenient high-performance liquid chromatography (HPLC) method for measuring ox-LDL levels in humans.

Methods

Human plasma lipoproteins were separated by a modified HPLC method using a diethylaminoethyl-type anion-exchange gel column with stepwise elution. Ox-LDLs were detected by postcolumn reaction with a regent containing cholesterol esterase and cholesterol oxidase. Particle size of each LDL fraction separated by HPLC was determined in 61 healthy subjects.

Results

Our HPLC method separated LDLs into three fractions, which were designated as LDL-1, LDL-2 and LDL-3, on the basis of their negative charges, with LDL-3 the most strongly retained fraction migrating fastest in the anodic direction, a property that reflects the net negative charge of the molecule. Western blot analysis revealed that apolipoprotein B100 in LDL-3 fraction was the most fragmented and oxidatively modified. When LDLs were oxidized in vitro by Cu2+ or 2,2-azo-bis (2-aminopropane)-2HCl or modified by various aldehydes, all of the LDL fractions migrated at the position of LDL-3. Further, among three fractions, particle size was smallest in LDL-3 fraction.

Conclusion

Here, we developed a convenient HPLC method and identified LDL-3 as oxidized LDL fractions, although ox-LDLs were present in LDL-2 fraction, albeit lesser concentrations than in LDL-3 subfraction. Measuring ox-LDL levels in human plasma by this method may be useful to evaluate atherosclerotic disorders.

Long-term treatment with pitavastatin is effective and well tolerated by patients with primary hypercholesterolemia or combined dyslipidemia

OBJECTIVES

The primary objective was to assess the safety and tolerability of pitavastatin 4mg once daily during 52 weeks treatment. The secondary objectives were to assess the effect on lipid and lipoprotein fractions and ratios, and LDL-C target attainment.

METHODS

Patients with primary hypercholesterolemia or combined dyslipidemia who had previously received pitavastatin, atorvastatin or simvastatin for 12 weeks during double-blind phase III studies received open-label pitavastatin 4mg once daily for up to 52 weeks.

RESULTS

Investigators at 72 sites enrolled 1353 patients who received at least one dose of pitavastatin 4mg; 155 (11.5%) patients discontinued treatment during the 52-week follow up. The proportion of patients achieving NCEP and EAS LDL-C targets at week 52 was 74.0% and 73.5% respectively. The reduction in LDL-C levels seen during the double-blind studies was sustained, while HDL-C levels rose continually during follow up, ultimately increasing by 14.3% over the initial baseline. Changes in other efficacy parameters (triglycerides, total cholesterol, non-HDL-C, Apo-A1 and Apo-B, high sensitivity C-reactive protein, oxidised LDL) and ratios (total cholesterol: HDL-C, non-HDL-C:HDL-C and Apo-B:Apo-A1) were sustained during 52-weeks treatment compared with the end of the double-blind studies. Pitavastatin was well tolerated: 4.1% of patients withdrew from the study due to treatment emergent adverse events (TEAEs) and none of the serious adverse events were considered treatment-related. No clinically significant abnormalities were associated with pitavastatin in routine laboratory variables, urinalysis, vital signs or 12-lead ECG. There were no reports of myopathy, myositis or rhabdomyolysis. The most common TEAEs were: increased creatine phosphokinase (5.8%), nasopharyngitis (5.4%) and myalgia (4.1%).

CONCLUSION

Pitavastatin 4mg once daily was effective and well tolerated during 52-weeks treatment in patients with primary hypercholesterolemia or combined dyslipidemia. Around three-quarters of patients achieved NCEP and EAS LDL-C targets at week 52, HDL-C levels rose continually during follow up, while changes in other efficacy parameters were sustained over the year-long study.

Quantification and characterization of aortic cholesterol in rabbits fed a high-cholesterol diet

Determination of fat percentage of aortic intimal area stained by Sudan III is useful as an index of atherosclerosis in the rabbit animal model. However, the determination of sudanophilic area of the thoracic aorta is two-dimensional and does not measure the third dimension of depth. The objective of the present study was to quantify and characterize aortic lipids using the gas-liquid chromatographic (GLC) technique and to determine whether elevated measurements of total cholesterol and cholesteryl esters was correlated with increased measurements of sudanophilic area staining of the thoracic aorta in rabbits given either a normal chow or a 1% cholesterol diet. The GLC results showed that there was a mean accumulation of 10.9 mg of cholesterol per gram of aortic tissue in the rabbits given a cholesterol diet (mean sudanophilic area of 23.8%). In contrast, rabbits on a normal chow diet had only a deposition of 0.58 mg of cholesterol per gram of the aortic tissue diet (mean sudanophilic area of 1.4%). The present study suggests that quantification of the aortic lipids can be performed by using GLC techniques and that it could be used as an alternative to the measurement of sudanophilic area when assessing the severity of atherosclerosis.

Green tea reduces LDL oxidability and improves vascular function

OBJECTIVE

Several different epidemiological studies have examined the association between the consumption of tea and coronary heart disease. Some, though not all, support the view that tea or flavonoids reduce the risk of cardiovascular heart disease. The aim of this study was to determine the short-to medium-term effect of a green tea extract on vascular function and lipid peroxidation as compared with placebo.

METHODS

The study was undertaken with 14 healthy women, none of whom were receiving any medical treatment. Measurements were made of antibodies and immune complexes by ELISA, endothelial dependent vascular function by Doppler ultrasound, and the concentration of oxidized LDL by TBARS.

RESULTS

The mean diameter of the brachial artery following the post-compression hyperaemia phase rose significantly (p < 0.0001) after treatment with green tea extract. Flow-mediated brachial artery vasodilation ranged from 5.68% for the placebo phase to 11.98% after the green tea extract (p = 0.02). The consumption of green tea extract was associated with a significant 37.4% reduction in the concentration of oxidized LDL (TBARS) (p = 0.017). The levels of anti-oxidized LDL IgM antibodies fell significantly after treatment (p = 0.002).

CONCLUSION

This study found that consumption of green tea extract by women for five weeks produced modifications in vascular function and an important decrease in serum oxidizability.

Targeting reactive oxygen species in hypertension

Oxidative stress plays an important role in the pathogenesis of hypertension. A number of sources of reactive oxygen species have been identified including NADPH oxidase, endothelial NO synthase, and xanthine oxidase. Inhibitors of these systems reduce blood pressure in experimental models. Targeted overexpression of antioxidant systems and interference with expression of oxidant systems has also been successfully used in animal models of hypertension. It is expected that these strategies will eventually be translated to human disease, but currently, the specificity and toxicity of such measures are not yet fulfilling quality criteria for treatment of humans. In the meantime, presumably nontoxic measures, such as administration of antioxidant vitamins, are the only available treatments for oxidative stress in humans. In this review, we discuss strategies to target oxidative stress both in experimental models and in humans. We also discuss how patients could be selected who particularly benefit from antioxidant treatment. In clinical practice, diagnostic procedures beyond measurement of blood pressure will be necessary to predict the response to antioxidants; these procedures will include measurement of antioxidant status and detailed assessment of vascular structure and function.

Effects of antioxidant-rich foods on vascular reactivity: review of the clinical evidence

The foods and nutrients discussed in this paper are components of dietary patterns that have been associated with lower cardiovascular disease risk. The focus of this review is on the effects of antioxidant foods on vascular health and discussion of their potential mechanisms of action. The foods reviewed include fruits and vegetables, red grapes and red wine, tea, cocoa/chocolate, and olive oil. The primary challenge in studying the cardioprotective components of a dietary pattern is in identifying mechanism(s) of action as well as the bioactive nutrients responsible. In selecting papers for this review, we focused on studies of whole foods and beverages that met the following criteria: 1) they are commonly consumed in typical diets, 2) they appear to have direct antioxidant effects, and 3) they have demonstrated effects on endothelial function in several human studies. The evidence presented herein suggests that dietary consumption of fruits and vegetables, red grapes and red wine, tea, chocolate, and olive oil may improve vascular reactivity, in part, by attenuating the adverse effects of oxidation on endothelial function. Additional research is needed to better understand the mechanism(s) by which antioxidant-rich foods and beverages favorably affect endothelial function and the extent to which this reflects direct antioxidant effects.

Oral administration of S-nitroso-N-acetylcysteine prevents the onset of non alcoholic fatty liver disease in rats

AIM: To evaluate the potential of S-nitroso-N-acetylcysteine (SNAC) in inhibition of lipid peroxidation and the effect of oral SNAC administration in the prevention of nonalcoholic fatty liver disease (NAFLD) in an animal model.

METHODS: NAFLD was induced in Wistar male rats by choline-deficient diet for 4 wk. SNAC-treated animals (n=6) (1.4 mg/kg/day of SNAC, orally) were compared to 2 control groups: one (n=6) received PBS solution and the other (n=6) received NAC solution (7 mg/kg/d). Histological variables were semiquantitated with respect to macro and microvacuolar fat changes, its zonal distribution, foci of necrosis, portal and perivenular fibrosis, and inflammatory infiltrate with zonal distribution. LOOHs from samples of liver homogenates were quantified by HPLC. Nitrate levels in plasma of portal vein were assessed by chemiluminescence. Aqueous low-density lipoprotein (LDL) suspensions (200 µg protein/mL) were incubated with CuCl₂ (300 µmol/L) in the absence and presence of SNAC (300 µmol/L) for 15 h at 37 °C. Extent of LDL oxidation was assessed by fluorimetry. Linoleic acid (LA) (18.8 µmol/L) oxidation was induced by soybean lipoxygenase (SLO) (0.056 µmol/L) at 37 °C in the presence and absence of N-acetylcysteine (NAC) and SNAC (56 and 560 µmol/L) and monitored at 234 nm.

RESULTS: Animals in the control group developed moderate macro and microvesicular fatty changes in periportal area. SNAC-treated animals displayed only discrete histological alterations with absence of fatty changes and did not develop liver steatosis. The absence of NAFLD in the SNAC-treated group was positively correlated with a decrease in the concentration of LOOH in liver homogenate, compared to the control group (0.7±0.2 nmol/mg vs 3.2±0.4 nmol/mg protein, respectively, P<0.05), while serum levels of aminotransferases were unaltered. The ability of SNAC in preventing lipid peroxidation was confirmed in in vitro experiments using LA and LDL as model substrates.

CONCLUSION: Oral administration of SNAC prevents the onset of NAFLD in Wistar rats fed with choline-deficient diet. This effect is correlated with the ability of SNAC to block the propagation of lipid peroxidation in vitro and in vitro.

Evaluation of enzymes involved in proteoglycan degradation in the wall of abdominal aortic aneurysms

The abdominal aortic aneurysm (AAA) wall represents an extreme example of arterial remodeling with disturbed elastin, collagen and proteoglycan metabolism. The aim of this study was to evaluate enzymes involved in the degradation of glycosaminoglycan chains and core proteins of proteoglycans in the AAA wall. The study material consisted of wall samples from 10 AAA. Fragments of 5 normal abdominal aortas from organ donors were used as a control. The activity of endoglycosidases, exoglycosidases and sulfatases was measured using colorimetric methods. To assess matrix metalloproteinases (MMPs), Western blot and zymography were performed. The activity of endoglycosidase degrading chondroitin-4-sulfate was lower in the AAA wall. Endoglycosidase degrading heparan sulfate and dermatan sulfate, arylosulfatase B, as well as all the exoglycosidases assessed demonstrated higher activities in the AAA wall. Furthermore, increased expression of MMP1, MMP2 and MMP9 was also shown in the AAA wall. Zymography revealed decreased activity of pro-MMP2 and presence of pro-MMP9 in the AAA wall compared to the wall of normal aorta. Extensive changes in the activity of glycosaminoglycan-degrading enzymes and MMPs may influence the organization of the extracellular matrix network and lead to previously demonstrated changes in the proteoglycan and glycosaminoglycan content in the AAA wall.

Oxidized low density lipoproteins, statin therapy and severity of coronary artery disease

BACKGROUND

The impact of statin therapy on the association between circulating levels of oxidized low density lipoproteins (OxLDL) and severity of coronary artery disease (CAD) has not been studied.

METHODS

OxLDLs were measured in 687 patients with angiographically proven CAD (320 patients, 46.6% on statin therapy and 367 patients, 53.4% not on statin therapy on admission) using the Mercodia Oxidized LDL Enzyme-Linked Immunosorbent Assay (ELISA).

RESULTS

Patients on statin therapy had lower levels of OxLDL (median [interquartile range]; 63.9 U/L [53.9; 79.8] versus 72.3 U/L [58.4; 86.1], P<0.001) and C-reactive protein (3.0 mg/L [1.2; 6.6] versus 4.0 mg/L [1.7; 13.1], P<0.001) than patients not on statins. Multivariable analysis showed that statin therapy was an independent predictor of lower levels of OxLDL (P=0.0001). In univariate analysis, OxLDL level did not differ significantly among the patients with 1-, 2-or 3-vessel disease (70.5 U/L [57.5; 85.6], 66.3 U/L [53.8; 82.6] and 68.2 U/L [57.0; 83.4], respectively, P=0.26). Multivariable logistic regression analysis showed that OxLDL was an independent correlate of angiographic severity of CAD (P=0.04) and that there was an interaction (P=0.038) between statins and OxLDL in that the increased levels of OxLDL were associated with more extensive CAD.

CONCLUSION

Patients with CAD who receive statins have lower levels of OxLDL and an attenuation of the relationship between circulating levels of OxLDL and CAD severity compared with patients who do not receive statins.

Therapeutic potential of nitric oxide donors in the prevention and treatment of atherosclerosis

Well-known risk factors for atherosclerosis include hypercholesterolaemia, hypertension, diabetes, and smoking. These conditions are associated with endothelial dysfunction, which itself is associated with reduced endothelial generation of nitric oxide (NO). This is an overview of the implications of NO generation in atherosclerosis and of the potential therapeutic benefit of drugs which donate NO, such as organic nitrates, nicorandil, and sydnonimines, or those which increase the availability of endogenous NO, such as statins, angiotensin-converting enzyme inhibitors, L-arginine, and tetrahydrobiopterin.

Influence of age and sex on levels of anti-oxidized LDL antibodies and anti-LDL immune complexes in the general population

Most studies of antibodies to oxidized LDL have been undertaken in patients with different diseases and cardiovascular risk factors. However, very few studies have researched the distribution and determining factors of antibodies to oxidized LDL in the general population. A total of 1,354 persons (817 females and 537 males) aged 5-65 years were included in this study. They were selected randomly from the population census of Málaga, in southern Spain. The females had lower levels of total cholesterol and triglycerides and higher levels of HDL-cholesterol and a very significant increase (P < 0.0001) in levels of anti-oxidized LDL [low density lipoprotein modified by malondialdehyde (MDA-LDL)] antibodies but no difference in levels of immune complexes consisting of LDL and IgG antibodies (anti-LDL immune complex). Younger persons (16-35 years) had higher levels of anti-oxidized LDL (MDA-LDL) antibodies than persons older than 35 years (P = 0.05). Levels of immune complexes were significantly higher (P = 0.05) in persons aged 5-15 years than in persons older than 40 years. A very weak association was found between levels of anti-oxidized LDL (MDA-LDL) antibodies and anti-LDL immune complexes. The higher prevalence of anti-oxidized LDL (MDA-LDL) antibodies in females and young persons is in agreement with studies that found an inverse association between atherosclerosis and the level of these antibodies.

Dyslipidemia in patients with type 2 diabetes. relationships between lipids, kidney disease and cardiovascular disease

Type 2 diabetes mellitus is a leading cause of morbidity and mortality. Cardiovascular disease (CVD) is the most prevalent complication and primarily accounts for the excess morbidity and mortality in diabetic patients, but microvascular complications, such as kidney disease and retinopathy, are frequent and contribute to the total disease burden. Lipid abnormalities in patients with type 2 diabetes are a major problem and associated with the increased risk of CVD. The most common pattern of dyslipidemia in these patients consists of elevated levels of triglycerides and low levels of high-density lipoprotein cholesterol. Low-density lipoprotein levels in these patients are often similar to that of the nondiabetic population, although there may be important qualitative differences in the pattern that contribute to the increased risk of CVD. Abnormal levels of urinary albumin occur in 30-40% of patients with type 2 diabetes and the presence of kidney disease enhances the mortality from CVD. Microalbuminuria, an early marker of diabetic nephropathy, is an independent risk factor for CVD. The increased levels of urinary albumin secretion may represent a more generalized vascular damage than renal microvascular injury alone. This Review focuses on the significance of diabetic dyslipidemia and microalbuminuria to CVD risk as well as to kidney complications. We also discuss the role of aggressive therapy to ameliorate vascular injury in the diabetic patient and reduce or prevent the cardiovascular and renal consequences of the disease.

Biology: risk factor modification by OCs and HRT lipids and lipoproteins

The many effects that the oestrogens and progestagens used in oral contraceptive (OC) and postmenopausal hormone replacement therapies (HRTs) have on lipoprotein metabolism are of importance because of the involvement of lipoproteins in endothelial damage and arterial occlusion. Lipoproteins promoting endothelial damage include: low density lipoprotein (LDL), particularly the small dense subfraction (sdLDL), remnants of very low density lipoprotein (VLDL) and chylomicron metabolism, and lipoprotein (a). High density lipoprotein (HDL) has pleiotropic effects that prevent or alleviate endothelial damage. Orally administered oestrogens increase hepatic triglyceride synthesis and VLDL secretion and increase the proportion of sdLDL. Oestrogens increase the rates of elimination of LDL, VLDL remnants and chylomicrons, suppress the synthesis of key enzymes of lipoprotein metabolism, hepatic and lipoprotein lipase, and increase synthesis of the principal apoprotein of HDL, apoAI. In general, progestagens oppose these effects according to type and dose. In OC and HRT users, this leads to a range of different lipoprotein profiles, which may differ from those evaluated with respect to vascular disease risk in population studies. Accumulating evidence suggests that the clinical implications of steroid induced changes in the lipoprotein profile will need to be evaluated independently of population-based evidence.

LDL Cholesterol is Associated with Small Abdominal Aortic Aneurysms

OBJECTIVE

To examine the relationship between serum lipids and abdominal aortic aneurysms (AAA).

METHODS

Two hundred and six males (>50 years) with AAA (> or =30 mm) detected in a population based screening programme were compared with 252 age-matched male controls in a nested case-control study. Smoking status, previous medical and family histories, height, weight, blood pressure, ankle brachial pressure index (ABPI) and non-fasting lipid profile were recorded.

RESULTS

Cases were found to have significantly higher LDL cholesterol than controls. LDL cholesterol was an independent predictor of the risk for aneurysms in a logistic regression model adjusting for smoking status, family history of AAA, history of ischaemic heart disease, presence of peripheral vascular disease, use of lipid lowering medication and treatment for hypertension. There was a linear effect with increased levels of LDL cholesterol increasing the risk of having a small aneurysm (test for trend p=0.03).

CONCLUSION

The highly significant association between LDL cholesterol and small aneurysms suggests that LDL, possibly acting via inflammatory mediated matrix degeneration, could be an initiating factor in the development of AAA. The ability of statin therapy to prevent AAA formation requires further investigation.

Antibodies to Oxidized Low-Density Lipoproteins and Angiographically Assessed Coronary Artery Disease in White Patients

Background— Low-density lipoprotein (LDL) can be oxidatively modified by reactive oxygen species, thus generating oxLDL. The latter induce formation of specific antibodies (oxLDLAb), which are detectable in patients with atherosclerosis, in which they might play a pathogenic or a protective role. Thus, we aimed to investigate the association of antibodies with oxidized LDLs (oxLDL) (oxLDLAbs) with coronary artery disease (CAD) and acute coronary syndromes.

Methods and Results— In a cross-sectional study of 529 consecutive patients undergoing quantitative coronary angiography for suspected CAD, we measured the titer of IgG oxLDLAbs by ELISA. With regression analysis techniques, we also investigated the determinants of oxLDLAb titer and the association of oxLDLAbs with CAD severity. We found no significant differences of oxLDLAb titer between groups of patients without and with different CAD severity. The oxLDLAb titer was 18.6 enzyme units (EU) (11.5 to 25.7 EU/mL) (mean, 95% CI) in patients without CAD; 16.8 EU (9.6 to 24.2 EU) in patients with stenosis <50%; and 19.9 EU (15 to 24.8 EU), 17.2 (13.8 to 20.6 EU), and 14.7 EU (12.1 to 17.3 EU) in those with in 1-, 2-, or 3-vessel ≥50% stenosis, respectively. Similarly, no differences of oxLDLAb titer between patients without and with acute coronary syndrome were found. The oxLDLAb titer correlated weakly with aging and with serum total, LDL, and HDL cholesterol and plasma homocysteine levels; however, only age and HDL cholesterol remained significant predictors of the oxLDLAb titer at a stepwise regression analysis.

Conclusions— The results of this study, which was adequately powered from the statistical standpoint, provided no evidence for an association of IgG oxLDLAb titer with angiographically assessed CAD in whites.

Near-Infrared Spectrometry of Abdominal Aortic Aneurysm in the ApoE-/- Mouse

Abdominal aortic aneurysms (AAAs) occur in 5-7% of people over age 60 in the United States. Early intervention in the disease process could have a significant impact on the incidence of complications and on patient survival, but identifying incipient aneurysms can be difficult. ApoE knockout mice develop AAAs following infusion of angiotensin II (AngII) by osmotic minipump into the subcutaneous space of mice at doses ranging from 500 to 1000 ng kg(-1) min(-1) for 7-28 days. These mice are used as models of AAA development. This study tested the hypothesis that near-IR spectrometry and PCR can determine AngII dose (SEE = 26 ng kg(-1) min(-1), SEP = 37 ng kg(-1) min(-1), r2 = 0.99) and collagen/elastin (C/E) ratio (SEE = 0.38, SEP = 0.39, r2 = 0.85) in mouse aortas.

Risk factor clustering in the insulin resistance syndrome and its relationship to cardiovascular disease in postmenopausal white, black, hispanic, and Asian/Pacific Islander women

The aim of this study was to examine how major components of the insulin resistance (IR) syndrome relate to each other and to cardiovascular disease (CVD) in postmenopausal women in 4 ethnic groups. Baseline data from the Women's Health Initiative (WHI) on 3,083 50- to 79-year-old women (1,635 white, 802 black, 390 Hispanic, and 256 Asian/Pacific Islander) were examined. Participants underwent a personal interview and a physical examination, blood samples were drawn, and a detailed cardiovascular history was ascertained. Factor analysis was used to assess the clustering and interdependence of groups of CVD-related IR syndrome variables. Four factors were identified. An obesity factor included IR in all groups and had a significant association with CVD in white (P =.0001) and Hispanic (P =.0024) women. A dyslipidemia factor (high-density lipoprotein [HDL], triglycerides, and HDL2: total HDL ratio) also included insulin and IR and was significantly correlated with CVD in black (P=.0006) and Hispanic (P =.0217) women and had a borderline association in white women (P =.068). Total and low-density lipoprotein (LDL) cholesterol did not relate to CVD in any group. Blood pressure was related weakly to CVD in white women (P =.0434) and strongly in black women (P =.0095). Components of the IR syndrome appear to be associated with CVD in postmenopausal women, although the magnitude of these relationships differed by ethnicity.

Effects of VasoCare therapy on the initiation and progression of atherosclerosis

VasoCare therapy, which involves the administration of autologous blood following the ex vivo exposure to physico-chemical stressors, has been shown to modulate immune responses. Since immune mechanisms have been recognized to be pivotal in the pathogenesis of atherosclerosis, we hypothesized that VasoCare treatment would inhibit atherosclerosis in LDL-R (-/-) mice. Three groups of LDL-R (-/-) mice were studied: a control group that was fed normal chow (Group I) and no other treatment; a control group that received a high cholesterol (HC) diet for 8 weeks (group II) with sham saline injections; and a third group (III) that received HC diet for 8 weeks and VasoCare treatment initiated after four weeks of HC feeding. Atherosclerotic area (AA), relative to total aortic area (TA), was assessed after 8 weeks of HC feeding by oil red O staining, and cross sectional plaque area at the level of the aortic valve leaflets was determined by quantitative morphometry. HC mice exhibited substantial aortic lipid deposition which was profoundly reduced in the VasoCare treated animals (AA/TA ratios in group II: 0.32+/-0.15 vs. group III: 0.17+/-0.06; P<0.05). This was associated with a significant decrease in cross sectional area of plaque in the aortic sinuses. VasoCare therapy also reduced the xanthoma formation and limb swelling characteristic of this animal model. However, cholesterol levels, measured by an enzymatic assay, showed similar marked increases in total serum cholesterol (CHO) in the animals receiving HC diet alone and those receiving the HC diet and VasoCare treatment [group I: 5.4+/-0.8 mM, group II: 46.7+/-3.6 mM, and group III: 44.7+/-2.8 mM (P<0.01 vs. group I)]. We conclude that VasoCare treatment inhibits progression of atherosclerotic lesions in a murine model of human familial hypercholesterolemia by a mechanism independent of cholesterol lowering.

High titres of serum antinuclear antibodies, mostly directed against nucleolar antigens, are associated with the presence of coronary atherosclerosis

BACKGROUND

Inappropriate inflammation is a key mechanism in the development of atherosclerosis. Antibodies against components of the atherosclerotic lesion, in particular, oxidised low density lipoprotein, have been described.

OBJECTIVE

To determine whether a systemic autoimmune response, characterised by the presence of high titres of antinuclear antibodies, is associated with the presence of coronary atherosclerosis.

METHODS

Serum was prepared from 40 subjects (aged 53-76) with at least 50% stenoses of three main coronary arteries (TVD subjects), and 30 subjects (aged 48-74) with no evidence of coronary atherosclerosis (NCA subjects) determined by coronary angiography.

RESULTS

Antinuclear antibodies (ANA), characterised by immunofluorescent detection of human antibodies bound to HEp-2000 cells, were detected at a titre of at least 1/40 in 28 (70%) of the TVD subjects, but only five (17%) of the NCA patients (odds ratio 11.67 (95% confidence interval (CI) 3.91 to 17.82; p<0.001)). Most ANA positive TVD subjects had a pattern typical of antibodies directed against nucleolar antigens. The antigen has not yet been identified, but several common extractable antigens were excluded. The presence of ANA was not associated with incidence of prior myocardial infarction among the TVD group.

CONCLUSION

The presence of ANA, commonly associated with autoimmune diseases, is substantially more prevalent among subjects with severe coronary atherosclerosis than those with normal coronary arteries. This association merits further assessment as a potentially useful indicator of increased risk of coronary heart disease.

Endothelial dysfunction in human diabetes

In nondiabetic individuals, a poor response to an endothelium-dependent vasodilator in coronary vessels has been shown to increase the likelihood of a future cardiovascular event. Such prospective data are not as yet available in patients with type 1 or type 2 diabetes. However, consistent with the greatly increased cardiovascular risk in these patients, endothelial dysfunction has been almost universally found to characterize patients with type 2 diabetes particularly. Endothelial dysfunction frequently coexists with features of insulin resistance, such as the presence of small dense low-density lipoprotein (LDL) particles even in nondiabetic individuals. This association is independent of obesity and other causes of endothelial dysfunction, such as LDL cholesterol, hypertension, and smoking. In patients with type 1 diabetes, endothelial dysfunction has been found in approximately half of the studies. In some but not all studies, endothelial dysfunction has been especially severe in patients with poor glycemic control. Reversal or amelioration of endothelial dysfunction has been documented by many commonly used therapeutic agents such as successful insulin therapy, fibrates, and angiotensin-converting enzyme inhibitors, but also with some but not all agents that act as antioxidants. Long-term studies addressing the prognostic significance of endothelial dysfunction and its reversal are urgently needed to determine whether measurement of endothelial function could be used to identify individuals at risk better than can be done at present using classic risk factor assessment among patients with type 2 diabetes especially.

Homocysteine and lipid peroxidation in haemodialysis: role of folinic acid and vitamin E

BACKGROUND

Cardiovascular diseases are the leading cause of death in haemodialysis patients. Hyperhomocysteinaemia is an independent risk factor. Basic research has provided strong evidence that oxidation of low-density lipoprotein (LDL) plays an important role in the pathogenesis of atherosclerosis. Oxidative stress, lipid metabolism alterations, and hyperhomocysteinaemia observed in haemodialysis patients could induce increases in LDL oxidation. This study was designed to determine the effect of folinic acid on hyperhomocysteinaemia and to assess the antioxidant efficacy of folinic acid. The antioxidant effect of folinic acid was compared with that of vitamin E.

METHODS

Sixteen stable patients (11 men, five women; mean age 54.3+/-6.32 years) on standard haemodialysis received 400 mg of vitamin E, orally, at the end of each haemodialysis session for 3 months. After a 1-month wash-out, they received 10 mg of folinic acid, intravenously, at the end of each haemodialysis session for an additional 3 months. Blood samples were drawn in the morning after an overnight fast and before dialysis. Plasma vitamin E was analysed by high-pressure liquid chromatography. Malondialdehyde (MDA) was determined using a fluorimetric method and plasma copper oxidized anti-LDL antibodies (Ab-LDLox) were measured with an ELISA method using native LDL and oxLDL as antigens. Plasma homocysteine was determined by an FPIA method.

RESULTS

Folinic acid supplements significantly reduced hyperhomocysteinaemia (-44%), MDA concentrations (-40%), and IgG-LDLox titres (-13%).

CONCLUSIONS

Treatment with folinic acid lowers plasma homocysteine levels and, like vitamin E, affords antioxidant protection, which prevents lipid peroxidation. This lowering of lipid peroxidation may reduce the risk of atherosclerosis and prevent or delay cardiovascular complications in HD patients.

APA hamster model for diabetic atherosclerosis. 2. Analysis of lipids and lipoproteins

Syrian hamsters of the APA strain (APA hamsters) have recently been shown to have atheromatous lesions in the aortic arches under diabetic condition induced by a single injection of streptozotocin (SZ). In that model, fatty streaks, which are the initial lesions of atherogenesis, develop by 6 weeks after the injection (WAI). In this study, we evaluated plasma lipid concentrations and lipoprotein profiles in diabetic APA hamsters at 6 WAI to reveal the early stage of atherogenesis clinicopathologically. As a result, by biochemical analysis, hyperglycemic APA hamsters showed signs of hypercholesterolemia and hypertriglyceridemia. Low-density lipoprotein (LDL) cholesterol significantly increased, but high-density lipoprotein (HDL) cholesterol significantly decreased. Agarose gel electrophoresis showed an obvious increase in the fractions of chylomicron, LDL and abnormal lipoprotein. Plasma LDL in diabetic animals was in a state more susceptible to oxidization. In addition, a significant increase in glycated LDL was also found in the diabetic animals by enzyme linked immunosorbent assay (ELISA). Moreover, lipid peroxidation product (4-hydroxynonenal (4 HNE))-adducted proteins and advanced glycation end-products (AGE) were immunohistochemically detected in the foam cells of the fatty streaks. These results revealed that diabetic APA hamsters had hyperlipidemia characterized by increases in chylomicron, LDL and abnormal lipoprotein, and suggested that oxidized LDL and/or glycated LDL might be actively uptaken by macrophages and play an important role in the initial stage of atherogenesis.

Arterial intimal retention of pro-atherogenic lipoproteins in insulin deficient rabbits and rats

Recent observations that remnants of triglyceride rich lipoproteins become trapped within the subendothelial of arterial vessels gives rise to the possibility that these particles could initiate the atherogenic cascade. Increased frequency and progression of atherosclerosis in diabetes might in part be a consequence of raised concentrations in plasma of remnant lipoproteins. In addition, diabetes may lead to changes in the arterial vasculature which exacerbate arterial retention of pro-atherogenic lipoproteins. To explore these possibilities, in this study we determined aortic retention of chylomicron remnants, which are of intestinal origin, and of hepatically derived low-density lipoproteins (LDL) in insulin deficient rabbits and rats. The two species were selected because of their disparate susceptibility to develop atherosclerosis in the presence of diabetes induced hyperlipidemia. Chylomicron remnants and LDL were differentially radiolabelled with a residual marker and injected simultaneously into conscious rabbits or rats. Arterial retention was determined 2 h after injection, and relative retention was expressed as a percentage of mean arterial exposure. We found in insulin deficient rabbits and rats that intimal and medial retention of chylomicron remnants was positively related to the degree of hyperglycemia and was significantly greater than in non-diabetic control groups. In contrast, insulin deficiency did not influence arterial retention of LDL. Rabbits which are susceptible to diabetes induced atherogenesis had significantly greater intimal retention of chylomicron remnants compared to rats. Results from this study support the hypothesis that chronic hyperglycemia promotes arterial retention of triglyceride rich remnant lipoproteins and that atherosclerotic susceptibility might be related to degree of remnant entrapment within the subendothelial space. Greater retention of remnant lipoproteins could in part explain the increased prevalence of atherogenesis in diabetes.

A caspase inhibitor decreases oxidized low-density lipoprotein-induced apoptosis in bovine endothelial cells

BACKGROUND

Apoptosis is a pathway of cell death orchestrated by a family of proteases called caspases. Oxidized low density lipoprotein (oxLDL) is a putative cause of atherogenesis. We examined the effect of oxLDL on endothelial cell (EC) apoptosis and the ability of a caspase antagonist to inhibit oxLDL-induced EC injury.

METHODS

Bovine ECs were plated at a concentration of 5.0 x 10(5) cells/ml and exposed to LDL oxidized by ultraviolet radiation at a concentration of 100 microgram oxLDL/ml for 20 h. Some ECs were pretreated with an irreversible caspase inhibitor (ZVAD). Samples were analyzed histologically. Apoptosis was measured using the Annexin V assay (flow cytometry) which detects phosphatidylserine on plasma membranes and confirmed by TUNEL assay (flow cytometry). Statistical assessments were performed using ANOVA.

RESULTS

ECs treated with LDL were morphologically similar to untreated cells. Cells treated with oxLDL demonstrated cytoplasmic shrinkage, plasma membrane blebbing, chromatin condensation, and loss of adhesion. These effects were diminished after pretreatment with the caspase inhibitor ZVAD. The Annexin V assay showed: (a) cells exposed to LDL had a 12 +/- 1% apoptosis rate, (b) exposure to oxLDL induced apoptosis in 30 +/- 0.3% of the cells, and (c) pretreatment with the caspase inhibitor ZVAD decreased the oxLDL-induced apoptosis to 16 +/- 1% (P < 0.05). This decrease in apoptosis was also reflected by an increase in the percentage of alive cells from 34 +/- 7% after oxLDL exposure to 55 +/- 6% after apoptosis inhibition with ZVAD. TUNEL assay demonstrated a 2.5-fold reduction in mean fluorescence intensity between cells treated with oxLDL alone and those treated with ZVAD, suggesting a significant decrease in apoptosis in the latter group.

CONCLUSIONS

We conclude that treatment of bovine ECs with oxLDL induces apoptosis which can be significantly reduced by a specific caspase inhibitor.