Apolipoprotein measurements: is more widespread use clinically indicated?

Association between atherogenic dyslipidemia and muscle quality defined by myosteatosis

Background

Myosteatosis, ectopic fat accumulation in skeletal muscle, is a crucial component of sarcopenia, linked to various cardiometabolic diseases. This study aimed to analyze the association between dyslipidemia and myosteatosis using abdominal computed tomography (CT) in a large population.

Methods

This study included 11,823 patients not taking lipid-lowering medications with abdominal CT taken between 2012 and 2013. Total abdominal muscle area (TAMA), measured at the L3 level, was segmented into skeletal muscle area (SMA) and intramuscular adipose tissue. SMA was further classified into normal attenuation muscle area (NAMA: good quality muscle) and low attenuation muscle area (poor quality muscle). NAMA divided by TAMA (NAMA/TAMA) represents good quality muscle. Atherosclerotic dyslipidemia was defined as high-density lipoprotein cholesterol (HDL-C) less than 40 mg/dL in men and 50 mg/dL in women, low-density lipoprotein cholesterol (LDL-C) greater than 160 mg/dL, triglycerides (TG) greater than 150 mg/dL, small dense LDL-C (sdLDL-C) greater than 50.0 mg/dL, or apolipoprotein B/A1 (apoB/A1) greater than 0.08.

Results

The adjusted odds ratios (ORs) of dyslipidemia according to the HDL-C and sdLDL definitions were greater in both sexes in the lower quartiles (Q1~3) of NAMA/TAMA compared with Q4. As per other definitions, the ORs were significantly increased in only women for LDL-C and only men for TG and ApoB/A1. In men, all lipid parameters were significantly associated with NAMA/TAMA, while TG and ApoB/A1 did not show significant association in women.

Conclusion

Myosteatosis measured in abdominal CT was significantly associated with a higher risk of dyslipidemia. Myosteatosis may be an important risk factor for dyslipidemia and ensuing cardiometabolic diseases.

Increased Apolipoprotein B/Apolipoprotein A-I Ratio Is Associated With Decline in Lung Function in Healthy Individuals: The Kangbuk Samsung Health Study

BACKGROUND

Lung dysfunction and high apolipoprotein B/apolipoprotein A-I (apoB/apoA-I) ratio are both recognized risk factors for cardiovascular disease. However, few studies have examined the association between the apoB/ApoA-I ratio and lung function. Therefore, we investigated whether this ratio is associated with decreased lung function in a large healthy cohort.

METHODS

We performed a cohort study on 68,418 healthy Koreans (34,797 males, mean age: 38.1 years) who underwent a health examination in 2019. ApoB/apoA-I ratio was categorized into quartiles. Spirometric values at the fifth percentile in our population were considered the lower limit of normal (LLN), which was used to define lung function impairment. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs), using the lowest quartile as the reference, were estimated to determine lung function impairment.

RESULTS

Mean apoB/apoA-I ratio was 0.67 ± 0.21. Subjects with the highest quartile of this ratio had the lowest predicted forced expiratory volume in one second (FEV1%) and forced vital capacity (FVC%) after controlling for covariates (P < 0.001). However, FEV1/FVC ratio was not significantly different among the four quartiles (P = 0.059). Compared with the lowest quartile (Q1, reference), the aORs (95% CI) for FEV1% < LLN across increasing quartiles (from Q2 to Q4) were 1.216 (1.094-1.351), 1.293 (1.156-1.448), and 1.481 (1.311-1.672) (P for trend < 0.001), respectively. Similarly, the aORs for FVC% < LLN compared with the reference were 1.212 (1.090-1.348), 1.283 (1.147-1.436), and 1.502 (1.331-1.695) with increasing quartiles (P for trend < 0.001). However, the aORs for FEV1/FVC < LLN were not significantly different among groups (P for trend = 0.273).

CONCLUSION

High apoB/apoA-I ratio was associated with decreased lung function. However, longitudinal follow-up studies are required to validate our findings.

Cholesterols, Apolipoproteins, and Their Associations with the Presence and Severity of Diabetic Retinopathy: A Systematic Review

Serum apolipoproteins have been reported as a more significant marker for diabetic retinopathy (DR) compared with serum cholesterols. This article aims to review the associations between serum cholesterols and apolipoproteins, and the presence and severity of DR. The protocol of this systematic review was registered at the PROSPERO registry (CRD42022303331). We conducted a systematic search of literature published between 2011 to 2022 using the search terms "serum cholesterol" AND/OR "lipoprotein" AND/OR "apolipoprotein" AND/OR "diabetic retinopathy". Fifteen studies were included in this review. Six studies assessed the association between serum cholesterols, apolipoproteins, and the presence of DR. Three studies reported lower levels of apolipoprotein A1, and one study reported higher levels of apolipoprotein B in patients with DR. The remaining nine studies compared serum cholesterol and apolipoprotein levels according to DR severity. Patients with more severe grades of DR presented with lower apolipoprotein A1 in six (66.7%) studies, higher apolipoprotein B levels in seven (77.8%) studies, and a higher apolipoprotein B/apolipoprotein A1 ratio in six out of seven (85%) studies. In conclusion, serum apolipoproteins, in particular the apolipoprotein B/apolipoprotein A1 ratio, were a more consistent marker for DR severity compared with serum cholesterols.

Leveraging knowledge of HDLs major protein ApoA1: Structure, function, mutations, and potential therapeutics

Apolipoprotein A1 (ApoA1) is a member of the Apolipoprotein family of proteins. It's a vital protein that helps in the production of high-density lipoprotein (HDL) particles, which are crucial for reverse cholesterol transport (RCT). It also has anti-inflammatory, anti-atherogenic, anti-apoptotic, and anti-thrombotic properties. These functions interact to give HDL particles their cardioprotective characteristics. ApoA1 has recently been investigated for its potential role in atherosclerosis, diabetes, neurological diseases, cancer, and certain infectious diseases. Since ApoA1's discovery, numerous mutations have been reported that affect its structural integrity and alter its function. Hence these insights have led to the development of clinically relevant peptides and synthetic reconstituted HDL (rHDL) that mimics the function of ApoA1. As a result, this review has aimed to provide an organized explanation of our understanding of the ApoA1 protein structure and its role in various essential pathways. Furthermore, we have comprehensively reviewed the important ApoA1 mutations (24 mutations) that are reported to be involved in various diseases. Finally, we've focused on the therapeutic potentials of some of the beneficial mutations, small peptides, and synthetic rHDL that are currently being researched or developed, since these will aid in the development of novel therapeutics in the future.

Apolipoproteins—New Biomarkers of Overweight and Obesity among Childhood Acute Lymphoblastic Leukemia Survivors?

Patients suffering from childhood acute lymphoblastic leukemia (ALL) are at risk of late adverse treatment-related effects. The examination of targeted biomarkers could be used to improve the diagnosis and prediction of life-threatening ALL sequelae. The purpose of this cross-sectional study was to search for treatment-related alterations in apolipoprotein (Apo) levels as potential markers of the occurrence of obesity in subjects treated for ALL, and to assess the relationships between weight, gender, anticancer treatment, and Apo concentrations. Fifty-eight ALL survivors were included in the study. The mean time of follow-up after treatment cessation was 5.41 ± 4.29 years. Serum levels of apolipoproteins were measured using a multiplex assay kit. Among ALL survivors, we observed a significant correlation of Apo-C1, Apo-C3, Apo-H, and Apo-J levels, depending on body mass index (BMI). Marked differences were observed in the area under the curve of Apo-A1, Apo-A2, Apo-C1, Apo-D. In our study, patients with a history of childhood ALL developed alterations in their Apo profile. Furthermore, this is the first study revealing that some apolipoproteins may act as valuable biomarkers useful in the prognosis of metabolic imbalance. We believe that this paper, at least partially, will highlight the importance of long-term prognosis of metabolic complications associated with the anticancer chemotherapy used to treat hematological malignancies in children.

Administration of Melatonin in Diabetic Retinopathy Is Effective and Improves the Efficacy of Mesenchymal Stem Cell Treatment

Stem cell transplantation is a promising therapeutic technique for the treatment of a variety of diseases; nevertheless, stem cell therapy may not always work as well as it could. The goal of this study was to test the hypothesis that employing a powerful antioxidant like melatonin improves stem cell transplantation success and potentiates stem cell function in the therapy of diabetic retinopathy. For this purpose, 50 adult male rats were divided into the following: control group: this group received 0.5 ml of 0.1 M of sodium citrate buffer (pH = 4.5) (intraperitoneal (I.P.)). The confirmed diabetic rats were divided into 4 groups: diabetic group: confirmed diabetic rats received no treatments with a regular follow of the blood glucose profile for 8 weeks; melatonin group: confirmed diabetic rats received melatonin (5 mg/kg/day); stem cell group: the confirmed diabetic rats were given intravitreal injection of stem cells (2 μl cell suspension of stem cells (3 × 10⁴ cells/μl)); and melatonin+stem cell group: confirmed diabetic rats received melatonin (5 mg/kg/day), orally once daily for 8 weeks, and 2 μl cell suspension of stem cells (3 × 10⁴ cells/μl) was carefully injected into the vitreous cavity. Our results showed that administration of melatonin and/or stem cell restored the retinal oxidative/antioxidant redox and reduced retinal inflammatory mediators. Coadministration of melatonin and stem cells enhanced the number of transplanted stem cells in the retinal tissue and significantly reduced retinal BDEF, VEGF, APOA1, and RBP4 levels as compared to melatonin and/or stem alone. We may conclude that rats treated with melatonin and stem cells had their retinal oxidative/antioxidant redox values restored to normal and their histological abnormalities reduced. These findings support the hypothesis that interactions with the BDEF, VEGF, APOA1, and RBP4 signaling pathways are responsible for these effects.

Afamin Levels and Their Correlation with Oxidative and Lipid Parameters in Non-diabetic, Obese Patients

Background: Afamin is a liver-produced bioactive protein and features α- and γ-tocopherol binding sites. Afamin levels are elevated in metabolic syndrome and obesity and correlate well with components of metabolic syndrome. Afamin concentrations, correlations between afamin and vitamin E, afamin and lipoprotein subfractions in non-diabetic, obese patients have not been fully examined. Methods: Fifty non-diabetic, morbidly obese patients and thirty-two healthy, normal-weight individuals were involved in our study. The afamin concentrations were measured by ELISA. Lipoprotein subfractions were determined with gel electrophoresis. Gas chromatography–mass spectrometry was used to measure α- and γ tocopherol levels. Results: Afamin concentrations were significantly higher in the obese patients compared to the healthy control (70.4 ± 12.8 vs. 47.6 ± 8.5 μg/mL, p < 0.001). Positive correlations were found between afamin and fasting glucose, HbA1c, hsCRP, triglyceride, and oxidized LDL level, as well as the amount and ratio of small HDL subfractions. Negative correlations were observed between afamin and mean LDL size, as well as the amount and ratio of large HDL subfractions. After multiple regression analysis, HbA1c levels and small HDL turned out to be independent predictors of afamin. Conclusions: Afamin may be involved in the development of obesity-related oxidative stress via the development of insulin resistance and not by affecting α- and γ-tocopherol levels.

Regulation of Apolipoprotein B by Natural Products and Nutraceuticals: A Comprehensive Review

Cardiovascular Disease (CVD) is the most important and the number one cause of mortality in both developing and industrialized nations. The co-morbidities associated with CVD are observed from infancy to old age. Apolipoprotein B100 (Apo B) is the primary apolipoprotein and structural protein of all major atherogenic particles derived from the liver including Very-Low- Density Lipoproteins (VLDL), Intermediate-density Lipoprotein (IDL), and Low-density Lipoprotein (LDL) particles. It has been suggested that measurement of the Apo B concentration is a superior and more reliable index for the prediction of CVD risk than is the measurement of LDL-C. Nutraceuticals and medicinal plants have attracted significant attention as it pertains to the treatment of non-communicable diseases, particularly CVD, diabetes mellitus, hypertension, and Nonalcoholic Fatty Liver Disease (NAFLD). The effect of nutraceuticals and herbal products on CVD, as well as some of its risk factors such as dyslipidemia, have been investigated previously. However, to the best of our knowledge, the effect of these natural products, including herbal supplements and functional foods (e.g. fruits and vegetables as either dry materials, or their extracts) on Apo B has not yet been investigated. Therefore, the primary objective of this paper was to review the effect of bioactive natural compounds on plasma Apo B concentrations. It is concluded that, in general, medicinal plants and nutraceuticals can be used as complementary medicine to reduce plasma Apo B levels in a safe, accessible, and inexpensive manner in an attempt to prevent and treat CVD.

Consumption of High-Oleic Soybean Oil Improves Lipid and Lipoprotein Profile in Humans Compared to a Palm Oil Blend: A Randomized Controlled Trial

Partially hydrogenated oils (PHO) have been removed from the food supply due to adverse effects on risk for coronary heart disease (CHD). High-oleic soybean oils (HOSBO) are alternatives that provide functionality for different food applications. The objective of this study was to determine how consumption of diets containing HOSBO compared to other alternative oils, with similar functional properties, modifies LDL cholesterol (LDLc) and other risk factors and biomarkers of CHD. A triple-blind, crossover, randomized controlled trial was conducted in humans (n = 60) with four highly-controlled diets containing (1) HOSBO, (2) 80:20 blend of HOSBO and fully hydrogenated soybean oil (HOSBO+FHSBO), (3) soybean oil (SBO), and (4) 50:50 blend of palm oil and palm kernel oil (PO + PKO). Before and after 29 days of feeding, lipids/lipoproteins, blood pressure, body composition, and markers of inflammation, oxidation, and hemostasis were measured. LDLc, apolipoprotein B (apoB), NonHDL-cholesterol (HDLc), ratios of total cholesterol (TC)-to-HDLc and LDLc-to-HDL cholesterol, and LDL particle number and small LDL particles concentration were lower after HOSBO and HOSBO+FHSBO compared to PO (specific comparisons p < 0.05). Other than TC:HDL, there were no differences in lipid/lipoprotein markers when comparing HOSBO+FHSBO with HOSBO. LDLc and apoB were higher after HOSBO compared to SBO (p < 0.05). PO + PKO increased HDLc (p < 0.001) and apolipoprotein AI (p < 0.03) compared to HOSBO and HOSBO+FHSBO. With the exception of lipid hydroperoxides, dietary treatments did not affect other CHD markers. HOSBO, and blends thereof, is a PHO replacement that results in more favorable lipid/lipoprotein profiles compared to PO + PKO (an alternative fat with similar functional properties).

Metabolic syndrome detection with biomarkers in childhood cancer survivors

PURPOSE

Augmented survival of childhood nephroblastoma and neuroblastoma has increased long-term side effects such as metabolic syndrome (MetS). Risk stratification is difficult after abdominal radiation because waist circumference underestimates adiposity. We aimed to develop a strategy for determining MetS in irradiated survivors using an integrated biomarker profile and vascular ultrasonography.

METHODS

The NCEP-ATPIII MetS-components, 14 additional serum biomarkers and 9 vascular measurements were assessed in a single-centre cohort of childhood nephroblastoma (n = 67) and neuroblastoma (n = 36) survivors and controls (n = 61). Multivariable regression models were used to study treatment effects. Principal component analysis (PCA) was used to study all biomarkers in a combined analysis, to identify patterns and correlations.

RESULTS

After 27.5 years of follow-up, MetS occurred more often in survivors (14%) than controls (3%). Abdominal radiotherapy and nephrectomy, to a lesser extent, were associated with MetS and separate components and with several biomarker abnormalities. PCA of biomarkers revealed a pattern on PC1 from favourable lipid markers (HDL-cholesterol, adiponectin) towards unfavourable markers (triglycerides, LDL-cholesterol, apoB, uric acid). Abdominal radiotherapy was associated with the unfavourable biomarker profile (β = 1.45, P = 0.001). Vascular measurements were not of added diagnostic value.

CONCLUSIONS

Long-term childhood nephro- and neuroblastoma survivors frequently develop MetS. Additional assessment of biomarkers identified in PCA - adiponectin, LDL, apoB, and uric acid - may be used especially in abdominally irradiated survivors, to classify MetS as alternative for waist circumference. Vascular ultrasonography was not of added value.

High-Density Lipoprotein Cholesterol in Age-Related Ocular Diseases

There is limited understanding of the specific role of high-density lipoprotein cholesterol (HDL-C) in the development of various age-related ocular diseases, despite it being a common measurable biomarker in lipid profiles. This literature review summarizes current knowledge of the role of HDL-C, if any, in pathogenesis and progression of four age-related ocular diseases, namely age-related macular degeneration (AMD), age-related cataract, glaucoma, and diabetic retinopathy (DR), and will primarily discuss epidemiological and genetic evidence.

Lipoprotein(a) and Apolipoproteins as Predictors for Diabetic Retinopathy and Its Severity in Adults With Type 2 Diabetes: A Case-Cohort Study

OBJECTIVES

Our aim in this study was to assess the relationship between serum lipoprotein(a) [Lp(a)] and apolipoproteins and the risk of developing diabetic retinopathy (DR).

METHODS

One thousand fifty-seven patients with type 2 diabetes were divided into 2 main groups and followed for 5 years: 637 patients without DR and 420 patients with DR. A group of patients with DR were then divided into 2 subgroups: 162 patients with nonproliferative DR (NPDR) and 163 patients with proliferative DR (PDR). The association between serum Lp(a) and apolipoproteins with NPDR and PDR was assessed using univariate and multivariate regression analyses. Receiver-operating characteristic curve analysis was performed based on the new cutoff values.

RESULTS

There was a positive relationship between Lp(a) and the presence of DR as well as a negative correlation between ApoA and DR (p<0.001 and p=0.03, respectively). We also found a positive association between ApoB and the severity of DR (p=0.008). ApoA1 had an area under the curve of 55.0% for the prediction of DR. The calculated cutoff values of ApoB/ApoA1 ratio (0.58 g/L) and ApoB (77.5 g/L) in detection of DR were lower than their standard cutoff values of 0.8 and 90 g/L, respectively. Also, the sensitivity of new cutoff values for ApoB and ApoB/ApoA1 ratio was higher than the standard value, but the specificity of the standard cutoff values for both was higher than our new cutoff value.

CONCLUSIONS

Serum Lp(a) and ApoA1 levels were independently associated with DR, and serum ApoB correlated with severity of DR. These measurements can be used for assessment and early treatment of this vision-threatening complication of diabetes.

The effects of supplementation with L-carnitine on apolipoproteins: A systematic review and meta-analysis of randomized trials

Randomized controlled trials (RCTs) have reported that L-carnitin may change serum apolipoproteins. However, the results of RCTs are contradictory. Our objective was to conduct a systematic review and meta-analysis to summarize earlier RCTs on the effects of L-carnitine supplementation on apolipoproteins B100 and AI. ISI web of science, Ovid, PubMed/Medline, Scopus, and Google Scholar were searched from inception to January 2019 using relevant keywords. Treatment effects were considered as weighted mean difference (MD) and the corresponding 95% confidence interval in concentrations of serum apolipoproteins. Random-effects model (Dersimonian-Liard) was used to estimate the overall summary effect. This meta-analysis was performed on fourteen trials. Our results indicated that L-carnitine supplementation has a non-significant effect on Apo B100 (mean difference (MD): 1.820 mg/dl; 95% CI: -3.367 to 7.006, p = 0.492) and Apo AI (MD: -0.119 mg/dl; 95% CI: -4.425 to 4.186, p = 0.957). We also found body mass index, L-carnitine dosage; health condition and intervention duration could change the results. We conclude that L-carnitine does not change Apo B100 and Apo AI concentration. Further trials with sufficient sample size are needed to confirm these findings.

Apolipoprotein profiling as a personalized approach to the diagnosis and treatment of dyslipidaemia

An elevated low-density lipoprotein cholesterol concentration is a classical risk factor for cardiovascular disease. This has led to pharmacotherapy in patients with atherosclerotic heart disease or high heart disease risk with statins to reduce serum low-density lipoprotein cholesterol. Even in patients in whom the target levels of low-density lipoprotein cholesterol are reached, there remains a significant residual cardiovascular risk; this is due, in part, to a focus on low-density lipoprotein cholesterol alone and neglect of other important aspects of lipoprotein metabolism. A more refined lipoprotein analysis will provide additional information on the accumulation of very low-density lipoproteins, intermediate density lipoproteins, chylomicrons, chylomicron-remnants and Lp(a) concentrations. Instead of measuring the cholesterol and triglyceride content of the lipoproteins, measurement of their apolipoproteins (apos) is more informative. Apos are either specific for a particular lipoprotein or for a group of lipoproteins. In particular measurement of apos in atherogenic particles is more biologically meaningful than the measurement of the cholesterol concentration contained in these particles. Applying apo profiling will not only improve characterization of the lipoprotein abnormality, but will also improve definition of therapeutic targets. Apo profiling aligns with the concept of precision medicine by which an individual patient is not treated as 'average' patient by the average (dose of) therapy. This concept of precision medicine fits the unmet clinical need for stratified cardiovascular medicine. The requirements for clinical application of proteomics, including apo profiling, can now be met using robust mass spectrometry technology which offers desirable analytical performance and standardization.

Relationship between serum apolipoproteins levels and retinopathy risk in subjects with type 2 diabetes mellitus

AIMS

Prognostic significance of apolipoproteins in diabetic retinopathy risk has not been well investigated. The aim of this study was to reveal the relationship between the risk of diabetic retinopathy and the levels of several apolipoproteins and their ratios in a 10-year prospective cohort.

METHODS

A total of 1023 diabetic patients without retinopathy were selected from a 10-year hospital-based diabetic cohort. In this cohort, all subjects had type 2 diabetes. Blood samples were obtained, and serum levels of several apolipoproteins were measured. In the follow-up period, diabetic retinopathy was diagnosed by two ophthalmologists through a series of ophthalmologic examinations. A Cox proportional hazard analysis was adopted to determine the relationship between the risk of diabetic retinopathy and the levels of several apolipoproteins and their ratios.

RESULTS

In the follow-up period, 315 diabetic patients were suffered from diabetic retinopathy, and the remaining 708 patients did not. Baseline serum level of apoAI ≥ 7.4 μmol/L was related to the decreased risk of diabetic retinopathy (HR 0.86, 95% CI 0.70-0.99). Baseline levels of apoCIII ≥ 6.3 μmol/L, apoE ≥ 1.1 μmol/L, apoCIII-to-apoAI ratio ≥ 0.9 and apoE-to-apoAI ratio ≥ 0.2 were associated with the increased risk of this complication (HR 1.25, 95% CI 1.04-1.49; HR 1.23, 95% CI 1.03-1.47; HR 1.34, 95% CI 1.11-1.60; HR 1.21, 95% CI 1.01-1.46).

CONCLUSION

Elevated level of apoAI might be a protective factor for diabetic retinopathy. Increased levels of apoCIII, apoE, apoCIII-to-apoAI and apoE-to-apoAI ratios might be risk factors for this complication.

Metabolic and immunological assessment of small-for-gestational-age children during one-year treatment with growth hormone: the clinical impact of apolipoproteins

Children born small for gestational age (SGA) are at a higher risk for metabolic disorders later in life. In this study, we aimed to characterize young SGA children without catch-up growth and evaluate the effects of GH treatment on endocrinological, metabolic, and immunological parameters. Study design is a one-year single hospital-based study included prospective observation of SGA patients during 12 months of GH treatment. Clinical and laboratory profiles of SGA children at baseline were compared with controls born appropriate size for age. Twenty-six SGA children (median age, 3.4 years) and 26 control children (median age, 3.8 years) were enrolled. Anthropometric, hematologic, biochemical, immunological, and endocrinological parameters were assessed at baseline and 1, 3, 6, 9, and 12 months after the start of GH treatment. As a result, median height SD score (SDS) of SGA children increased by +0.42 with 12-month GH treatment. Body mass index SDS was lower in SGA children than in controls. Serum apolipoprotein A1 increased, whereas apolipoprotein B decreased during GH treatment. Serum leptin and resistin levels, which were lower in SGA children than in controls at baseline, did not change remarkably with GH treatment. Monocyte counts, which were lower in SGA patients at baseline, increased after GH treatment. Neutrophil counts significantly increased after GH treatment. Natural killer cell ratios, which were higher in SGA patients, decreased after GH treatment. In conclusion, there was no evidence suggesting metabolic abnormalities in SGA children. Serum apolipoprotein changes might predict the beneficial role of GH treatment in lowering cardiometabolic risk.

Vitreous levels of apolipoprotein A1 and retinol binding protein 4 in human rhegmatogenous retinal detachment associated with choroidal detachment

Purpose

This study aims to quantify the concentration of apolipoprotein A1 (APOA1) and retinol binding protein (RBP4) expressed in the vitreous humors of patients with rhegmatogenous retinal detachment associated with choroidal detachment (RRDCD), rhegmatogenous retinal detachment (RRD), and idiopathic epimacular membrane (IEM). This study also aims to investigate the potential role of APOA1 and RBP4 as biomarkers of RRDCD.

Methods

Enzyme-linked immunosorbent assay (ELISA) kits were used to obtain levels of APOA1 and RBP4 from the vitreous humor samples of 76 primary patients. These patients included 23 patients with RRDCD, 28 patients with RRD, and 24 patients with IEM. All patients were undergoing planned pars plana vitrectomy. The differences between the concentrations of the molecular biomarkers among different patient groups were analyzed using the Mann-Whitney U-test for nonparametric values and independent samples t-test or one-way ANOVA analysis for parametric data. The relationship between the molecular biomarkers, grades of proliferative vitreoretinopathy (PVR), and quadrants of retinal detachment were analyzed using nonparametric Spearman's rank correlation analysis.

Results

The vitreous concentrations of APOA1 and RBP4 were statistically significantly higher in the RRDCD group compared to the RRD and IEM groups. Patients with severe PVR demonstrated a higher concentration of APOA1 and RBP4 compared to those with mild PVR, but this finding was not statistically significant. There was a statistically significant positive correlation between APOA1 and RBP4 in the RRDCD and RRD groups. Nonparametric Spearman's rank correlation analysis revealed that levels of APOA1 and RBP4 increased statistically significantly with an increasing number of detached retinal quadrants in the RRDCD and RRD groups.

Conclusions

The findings of this study allude to the potential of APOA1 and RBP4 as specific biomarkers of RRDCD. The findings of this study may contribute to increased understanding regarding the role of APOA1 and RBP4 in RRDCD.

Genetically Determined Plasma Lipid Levels and Risk of Diabetic Retinopathy: A Mendelian Randomization Study

Results from observational studies examining dyslipidemia as a risk factor for diabetic retinopathy (DR) have been inconsistent. We evaluated the causal relationship between plasma lipids and DR using a Mendelian randomization approach. We pooled genome-wide association studies summary statistics from 18 studies for two DR phenotypes: any DR (N = 2,969 case and 4,096 control subjects) and severe DR (N = 1,277 case and 3,980 control subjects). Previously identified lipid-associated single nucleotide polymorphisms served as instrumental variables. Meta-analysis to combine the Mendelian randomization estimates from different cohorts was conducted. There was no statistically significant change in odds ratios of having any DR or severe DR for any of the lipid fractions in the primary analysis that used single nucleotide polymorphisms that did not have a pleiotropic effect on another lipid fraction. Similarly, there was no significant association in the Caucasian and Chinese subgroup analyses. This study did not show evidence of a causal role of the four lipid fractions on DR. However, the study had limited power to detect odds ratios less than 1.23 per SD in genetically induced increase in plasma lipid levels, thus we cannot exclude that causal relationships with more modest effect sizes exist.

Correlation of metabolic syndrome severity with cardiovascular health markers in adolescents

BACKGROUND AND OBJECTIVES

The presence of metabolic syndrome (MetS) in childhood is a significant risk factor for later cardiovascular disease (CVD). Recent data showed temporal decreases in a sex- and race/ethnicity-specific MetS severity z-score among U.S. adolescents. Our goal was to characterize the relationship of this MetS z-score with other CVD risk indicators and assess their temporal trends and lifestyle influences.

METHODS

We analyzed 4837 participants aged 12-20years from the National Health and Nutrition Examination Survey by 2-year waves from 1999 to 2012. We used linear regression to compare MetS z-score and dietary factors with serum levels of low-density lipoprotein (LDL), apolipoprotein-B (ApoB), high-sensitivity C-reactive protein (hsCRP) and uric acid.

RESULTS

MetS severity z-score was positively correlated with LDL, ApoB, hsCRP, and uric acid measurements (p<0.0001 for all). These correlations held true among individual racial/ethnic groups. LDL, ApoB, and hsCRP measurements decreased over time among U.S. adolescents (p=0.002, p<0.0001, and p=0.024, respectively). Saturated fat consumption was positively correlated with LDL (p=0.005) and ApoB (p=0.012) and inversely related to serum uric acid (p=0.001). Total caloric intake was inversely related to LDL (p=0.003) and serum uric acid (p=0.003). Unsaturated fat, carbohydrate, and protein consumption were not related to LDL, ApoB, hsCRP, or serum uric acid.

CONCLUSIONS

There is a positive correlation between MetS severity and all four CVD risk indicators studied. LDL, ApoB, and hsCRP showed favorable temporal trends, which could be related to similar trends in MetS z-score. These data support the importance of considering multiple inter-related factors in clinical CVD risk assessment.

Comparison of Serum Apolipoproteins and Traditional Lipids in Eyes with Diabetic Retinopathy in Indian Population: A Case Series

Purpose:

To review the associations of serum lipoproteins and apolipoproteins with diabetic retinopathy (DR).

Materials and Methods:

This was a cross-sectional study of patients of DR. DR was graded according to modified Airlie House Classification system. Traditional serum lipids (total, low-density lipoprotein [LDL], and high-density lipoprotein [HDL] cholesterol and triglycerides [TGs]), apolipoprotein AI (apoAI), apolipoprotein B (apoB), and apoB-to-apoAI ratios were assessed. The analysis of variance test was applied. P < 0.05 was considered statistically significant, and P < 0.001 was considered highly significant.

Results:

Twenty-four patients with DR were evaluated. Serum apoAI was statistically significantly associated with a reduced likelihood of having more severe DR levels (P < 0.001). Increasing levels of apoB (P < 0.001) and apoB-to-apoAI ratio (P < 0.001) were statistically significantly associated with increasing DR severity levels. The association of total (P > 0.05) and LDL cholesterol (P > 0.05) with severity of DR was not statistically significant. HDL cholesterol levels were inversely associated with the severity of DR (P < 0.05). TGs were also statistically significantly associated with the severity of DR (P < 0.05).

Conclusion:

Serum apolipoprotein levels may be stronger biomarkers of DR than traditional lipids.

Renin-angiotensin system at the crossroad of hypertension and hypercholesterolemia

AIM

The aim of this study is to discuss the reliable scientific evidence of an interactive link between hypertension and hypercholesterolemia considering the metabolic pathways and the pathogenetic mechanisms connecting the two risk factors.

DATA SYNTHESIS

Hypertension and hypercholesterolemia are highly prevalent in the general population and their coexistence in the same subjects additively increases the risk of cardiovascular disease. Probably, hypercholesterolemia is also a risk factor for the development of hypertension. On the other side, it is also possible that lipid-lowering treatment could improve blood pressure control. Although the mechanisms of interaction between these two risk factors have not been completely elucidated thus far, there is rapidly growing evidence that the involvement of the renin-angiotensin system (RAS) can be considered as the common link between hypertension and hypercholesterolemia. In particular, hypercholesterolemia seems to promote the upregulation of type 1 angiotensin II (AT1) receptor genes because of an increase in the stability of mRNA followed by structural overexpression of vascular AT1 receptors for angiotensin II. The treatment of both risk factors greatly improves individual risk profile, especially when statins and RAS blockers are used together.

CONCLUSIONS

Hypertension and hypercholesterolemia are highly coprevalent and strongly related from a pathophysiological point of view. The RAS could be the main mediator of this link.

Lipoprotein profiling methodology based on determination of apolipoprotein concentration

Aim: Abnormal lipid metabolism results in the alteration of lipid compositions in lipoproteins; therefore an accurate and quantitative analytical approach is required for the detailed structural characterization of lipoproteins. However, the specific lipid composition of each lipoprotein particle is poorly understood. Materials & methods: Lipid composition of very-low-density lipoprotein and low-density lipoprotein particles derived from myocardial infarction-prone rabbits was determined by normalization of lipidomics data using apoB-100 levels. Results: The ratio of lipid levels between very-low-density lipoprotein and low-density lipoprotein particles was different according to not only lipid classes, but also phosphatidylethanolamine subclasses by applying our developed methodology to myocardial infarction-prone rabbits. Conclusion: Our novel analytical approach represents to be a potentially useful tool to obtain particle-specific lipid components of lipoproteins.

Black garlic: A critical review of its production, bioactivity, and application

Black garlic is obtained from fresh garlic (Allium sativum L.) that has been fermented for a period of time at a controlled high temperature (60-90°C) under controlled high humidity (80-90%). When compared with fresh garlic, black garlic does not release a strong offensive flavor owing to the reduced content of allicin. Enhanced bioactivity of black garlic compared with that of fresh garlic is attributed to its changes in physicochemical properties. Studies concerning the fundamental findings of black garlic, such as its production, bioactivity, and applications, have thus been conducted. Several types of black garlic products are also available in the market with a fair selling volume. In this article, we summarize the current knowledge of changes in the components, bioactivity, production, and applications of black garlic, as well as the proposed future prospects on their possible applications as a functional food product.

Lipid profile among girls with systemic lupus erythematosus

The aim of the study was to describe biomarkers of lipid metabolism associated with increased cardiovascular risk and their correlation with disease variables and markers of inflammation in adolescent females with systemic lupus erythematosus (SLE). This cross-sectional controlled study evaluated 33 adolescent females with juvenile SLE and 33 healthy controls. Anthropometric data, SLE disease activity index (SLEDAI), medications, proteinuria, ultra-sensitive C-reactive protein (us-CRP), lipid profile (total cholesterol, LDL-c, HDL-c and triglycerides), apolipoproteins A and B (Apo A-I and B), paraoxonase, and myeloperoxidase were evaluated. Median age of the patients and the median disease duration were 16.7 years and 54 months, respectively. SLEDAI scores above 4 were observed in 11 (33.3 %) patients. Moreover, 12 (36.4 %) patients were overweight, and 5 (15.2 %) had low height for age ratios. Dyslipidemia was observed in 13 (39.4 %) patients and in 7 (21.2 %) controls with a decrease in HDL-c concentrations in SLE patients even after adjustment for their nutritional status. In the group with SLE, us-CRP concentrations were inversely correlated with LDL-c/ApoB ratio (p = 0.031). After multivariate regression analysis, the SLE group showed lower concentration of Apo A-I and a decreased LDL-c/ApoB ratio. SLE adolescent females with low disease activity, with preserved kidney function and on low dose of corticosteroids, regardless of nutritional status and food intake, have proatherogenic lipid biomarkers, which may contribute to an increased atherosclerotic risk.

Stronger relationship of serum apolipoprotein A-1 and B with diabetic retinopathy than traditional lipids

AIM

Diabetic retinopathy (DR) is the most common preventable cause of blindness where early detection and treatment can be sight-saving. Search for biomarkers of the disease has been relentless. We aimed to determine whether lipoproteins apolipoproteins A1 and B1 (Apo-A1 and Apo-B1) have stronger associations with DR in contrast to conventionally measured low-density lipoprotein (LDL) and high-density lipoprotein cholesterol levels.

MATERIALS AND METHODS

We performed a cross-sectional study and studied 117 patients. Serum lipid profile was assessed by autoanalyzer. Serum Apo-A1 and Apo-B were measured using immunoturbidimetric kit on an autoanalyzer. Apo-B/A1 ratio was calculated. Retinopathy was graded from the digital retinal photographs, taken with nonmydriatic auto fundus camera and classified according to International Clinical DR Disease Severity Scale.

RESULTS

Mean Apo-A1 for mild, moderate, severe retinopathy, and proliferative DR (PDR) shows a significant negative correlation (P = 0.001) with severity of retinopathy. Mean Apo-B for mild, moderate, severe, PDR displayed a significant positive correlation with severity of retinopathy (P = 0.001). Mean Apo-B/A1 for mild, moderate, severe, PDR showed highly significant positive correlation with severity of retinopathy (P < 0.001). In contrast, mean LDL for mild, moderate, severe, PDR showed insignificant association with severity of DR (P = 0.081).

CONCLUSION

Apo-A1 and Apo-B have a stronger association with the development of DR than traditional lipids and can thus facilitate early detection and treatment of the disease.

Apolipoprotein A-I and B and Subjective Global Assessment relationship can reflect lipid defects in diabetic retinopathy

OBJECTIVE

Elevated lipid levels increase complications of diabetic retinopathy (DR). Uncontrolled diabetes increases these complications and causes unintentional weight loss, indicating an apparently normal body mass index (BMI). Thus, it is easy to assume that patients with DR and a normal BMI have optimal lipid status. Apolipoprotein (Apo) A-I and Apo B levels differentially indicate serum lipid status in DR. Subjective Global Assessment (SGA) scores are associated with DR status. If SGA scores and serum Apo A-I and B levels are found to be interrelated, their relationship can reflect lipid defects in patients with DR despite apparently normal BMI. The aim of the present study was to investigate the possible relationship between serum Apo A-I and B levels and SGA scores of patients with DR.

METHOD

This was a case-control study conducted from November 2011 to April 2014. Serum Apo A-I and B levels and SGA scores were calculated for 40 healthy controls, 48 individuals without DR, 49 nonproliferative DR cases, and 48 proliferative DR cases. Pearson's correlation analysis was applied between Apo A-I, Apo B, Apo B/Apo A-I ratio, and SGA scores.

RESULTS

Negative correlation was observed between serum Apo A-I level (r = -0.567, P < 0.001) and positive correlation between serum Apo B level (r = 0.451, P < 0.001) and Apo B/Apo A-I ratio (r = 0.597, P < 0.001) with escalating SGA scores.

CONCLUSION

To our knowledge, this is the first study to report a novel correlation between serum Apo A-I, Apo B and Apo B/Apo A-I ratio and SGA scores. SGA scores can help predict lipid abnormalities in patients with DR even when they have an apparently normal BMI.

Lipoprotein Biomarkers and Risk of Cardiovascular Disease: A Laboratory Medicine Best Practices (LMBP) Systematic Review

BACKGROUND

Controversy exists about the incremental utility of nontraditional lipid biomarkers [e.g., apolipoprotein (apo) B, apo A-I, and non-HDL-C] in improving cardiovascular disease (CVD) risk prediction when added to a conventional model of traditional risk factors (e.g., total cholesterol, LDL cholesterol, HDL cholesterol, sex, age, smoking status, and blood pressure). Here we present a systematic review that was conducted to assess the use of nontraditional lipid biomarkers including apo B, apo A-I, apo B/A-I ratio, and non-HDL-C in improving CVD risk prediction after controlling for the traditional risk factors in populations at risk for cardiovascular events.

CONTENT

This systematic review used the Laboratory Medicine Best Practices (LMBP™) A-6 methods. A total of 9 relevant studies published before and including July 2015 comprised the evidence base for this review. Results from this systematic review indicated that after the adjustment for standard nonlipid and lipid CVD risk factors, nontraditional apolipoprotein biomarkers apo B (overall effect = relative risk: 1.31; 95% CI, 1.22-1.40; 4 studies) and apo B/apo A-I ratio (overall effect = relative risk: 1.31; 95% CI, 1.11-1.38; 7 studies) resulted in significant improvement in long-term CVD risk assessment.

SUMMARY

Available evidence showed that nontraditional lipid biomarkers apo B and apo B/apo I ratio can improve the risk prediction for cardiovascular events after controlling for the traditional risk factors for the populations at risk. However, because of insufficient evidence, no conclusions could be made for the effectiveness of apo A-I and non-HDL-C lipid markers to predict the CVD events, indicating a need for more research in this field.

Association of Serum Apolipoprotein B with the Increased Risk of Diabetes in Korean Men

This study aimed to investigate the association of Apolipoprotein B (ApoB) with the risk of diabetes in Koreans. Korean men (n = 790, 40-79 years) who had been never diagnosed for diabetes before participating were enrolled. Subjects were categorized into normal fasting glucose (NFG, n = 519), impaired fasting glucose (IFG, n = 188) and newly-onset diabetes (n = 83) according to fasting glucose levels. Age was not significantly different among the subgroups. Mean values of BMI, waist circumference, Blood pressure(BP), triglyceride, non-HDL cholesterol were significantly higher in IFG or newly-onset diabetic subjects compared to NFG subjects. The levels of glucose, insulin, free fatty acid, insulin resistance and ApoB were highest in diabetic patients and lowest in NFG subjects. According to ApoB level, subjects were divided into two groups (high-ApoB group: ≥ 87.0 mg/dL vs. low-ApoB group: < 87.0 mg/dL). The risk of diabetes was higher in the high-ApoB group than the low-ApoB group [OR₀: 2.392, (95% CI: 1.470-3.893), P₀ < 0.001]. This association was maintained after adjusted for age and BMI [OR₁: 2.228, (95% CI: 1.362-3.646), P₁ = 0.001] and further adjustment for blood pressure, triglyceride, HDL-cholesterol, LDL-cholesterol, non-HDL-cholesterol, ApoA1 and adiponectin [OR₂: 1.984, (95% CI: 1.001-4.064), P₂ = 0.049]. The association was much greater in subjects with metabolic syndrome (MetS) [OR₁: 2.805 (95% CI: 1.137-5.737), P₁ = 0.005] than in those without [OR₁: 1.917 (95% CI: 0.989-3.718), P₁ = 0.054]. After 3-month, further investigation was randomly performed in subjects with NFG or IFG who agreed to reinvestigation. Multiple stepwise regression analysis revealed that net change of ApoB levels was a main contributor to the net change of glucose levels (standardized b-coefficient: 0.315, p = 0.002). In conclusion, ApoB levels are closely associated with the increased risk of diabetes in Korean men.

Learning from biology: synthetic lipoproteins for drug delivery

Synthetic lipoproteins represent a relevant tool for targeted delivery of biological/chemical agents (chemotherapeutics, siRNAs, photosensitizers, and imaging contrast agents) into various cell types. These nanoparticles offer a number of advantages for drugs delivery over their native counterparts while retaining their natural characteristics and biological functions. Their ultra-small size (<30 nm), high biocompatibility, favorable circulation half-life, and natural ability to bind specific lipoprotein receptors, i.e., low-density lipoprotein receptor (LDLR) and Scavenger receptor class B member 1 (SRB1) that are found in a number of pathological conditions (e.g., cancer, atherosclerosis), make them superior delivery strategies when compared with other nanoparticle systems. We review the various approaches that have been developed for the generation of synthetic lipoproteins and their respective applications in vitro and in vivo. More specifically, we summarize the approaches employed to address the limitation on use of reconstituted lipoproteins by means of natural or recombinant apolipoproteins, as well as apolipoprotein mimetic molecules. Finally, we provide an overview of the advantages and disadvantages of these approaches and discuss future perspectives for clinical translation of these nanoparticles.

Atherogenic subfractions of lipoproteins in the treatment of metabolic syndrome by physical activity and diet - the RESOLVE trial

Background

We aimed to comprehensively evaluate lipoprotein profile including lipid particle size following a lifestyle intervention in metabolic syndrome (MetS) volunteers and to assess the associations between lipoprotein subfractions and carotid-intima-media-thickness (CIMT) – a surrogate indicator of atherogenesis.

Methods

100 participants (50–70 years) from the RESOLVE trial, underwent a one-year follow-up beginning with a three-week residential program combining high exercise volume (15-20 h/week), restrictive diet (-500 kcal/day), and education. For baseline references, 40 aged-matched healthy controls were recruited. Independent associations between subfractions of lipoproteins and CIMT were evaluated using a generalized estimating equations model accounting for variation in correlations between repeated measures. The lipoprotein subfractions profile was assessed using Lipoprint® electrophoresis allowing to separate: the very low-density lipoprotein (VLDL) fraction, then the intermediate-density lipoprotein (IDL) C, B and A, the low-density lipoprotein (LDL) with subfractions 1 and 2 as large LDL and subfractions 3 to 7 as small dense LDL (sdLDL), and the high density lipoprotein (HDL) subfractions categorized into large, intermediate, and small HDL. Apolipoproteins A1 and B were also measured.

Results

78 participants completed the program. At baseline, apolipoproteins B/A1, VLDL, sdLDL and small HDL were higher in MetS than in healthy controls; IDL, LDL size, large and intermediate HDL were lower. Despite time-related regains during the follow-up, lipoprotein subfractions traditionally involved in cardiovascular risk, such as sdLDL, improved immediately after the residential program with values closest to those of healthy controls. CIMT improved throughout the lifestyle intervention. Using a generalized estimating equations model, none of the subfractions of lipoproteins nor apolipoproteins were linked to CIMT.

Conclusions

Lipoprotein subfractions traditionally involved in CVR, decreased after the 3-week residential program. During a 12 month follow-up, the time-related regains remained closer to the values of healthy controls than they were at baseline. CIMT improved throughout the lifestyle intervention. However, we failed to demonstrate a link between some lipoprotein subfractions and the atherogenicity directly measured from the wall thickness of arteries (CIMT). Further investigations are required to explore the atherogenicity of lipoprotein subfractions.

Trial registration

NCT00917917

The value of Apolipoprotein B/Apolipoprotein A1 ratio for metabolic syndrome diagnosis in a Chinese population: a cross-sectional study

Background

The apoB/apoA1 ratio has been reported to be associated with the metabolic syndrome (MetS), and it may be a more convenient biomarker in MetS predicting. However, whether apoB/apoA1 ratio is a better indicator of metabolic syndrome than other biomarkers and what is the optimal cut-off value of apoB/apoA1 ratio as an indicator of metabolic syndrome in Chinese population remain unknown. Thus, we carried out the current study to assess the predictive value of apoB/apoA1 ratio and determine the optimal cut-off value of apoB/apoA1 ratio for diagnosing MetS in a Chinese population.

Method

We selected 1,855 subjects with MetS and 6,265 individuals without MetS based on the inclusion and exclusion criteria from the China Health Nutrition Survey (CHNS) in 2009. MetS was identified based on the diagnostic criteria of International Diabetes Federation (2005). Logistic regression was used to estimate the association between the apoB/apoA1 ratio and risk of MetS, and receiver operating characteristics (ROC) curve analysis was performed to test the predictive value of apoB/apoA1 ratio and calculate the appropriate cut-off value.

Results

Compared with the lowest quartile of apoB/apoA1 ratio, subjects in the fourth quartile had a higher risk of MetS in both men [odds ratio (OR) = 2.64, 95% confidence interval (CI) =1.82-3.83] and women (OR = 5.18, 95% CI = 3.87-6.92) after adjustment for potential confounders. The optimal cut-off value of apoB/apoA1 ratio for MetS detection was 0.85 in men and 0.80 in women. Comparisons of ROC curves indicated that apoB/apoA1 ratio was better than traditional biomarkers in predicting MetS.

Conclusion

Our results suggest that, apoB/apoA1 ratio has a promising predictive effectiveness in detection of MetS. An apoB/apoA1 ratio higher than 0.85 in men and 0.80 in women may be a promising and convenient marker of MetS.

Evaluation of interspecimen trypsin digestion efficiency prior to multiple reaction monitoring-based absolute protein quantification with native protein calibrators

Implementation of quantitative clinical chemistry proteomics (qCCP) requires targeted proteomics approaches, usually involving bottom-up multiple reaction monitoring-mass spectrometry (MRM-MS) with stable-isotope labeled standard (SIS) peptides, to move toward more accurate measurements. Two aspects of qCCP that deserve special attention are (1) proper calibration and (2) the assurance of consistent digestion. Here, we describe the evaluation of tryptic digestion efficiency by monitoring various signature peptides, missed cleavages, and modifications during proteolysis of apolipoprotein A-I and B in normo- and hypertriglyceridemic specimens. Absolute quantification of apolipoprotein A-I and B was performed by LC-MRM-MS with SIS peptide internal standards at two time points (4 and 20 h), using three native protein calibrators. Comparison with an immunoturbidimetric assay revealed recoveries of 99.4 ± 6.5% for apolipoprotein A-I and 102.6 ± 7.2% for apolipoprotein B after 4 h of trypsin digestion. Protein recoveries after 20 h trypsin incubation equaled 95.9 ± 6.9% and 106.0 ± 10.0% for apolipoproteins A-I and B, respectively. In conclusion, the use of metrologically traceable, native protein calibrators looks promising for accurate quantification of apolipoprotein A-I and B. Selection of rapidly formed peptides, that is, with no or minor missed cleavages, and the use of short trypsin incubation times for these efficiently cleaved peptides are likely to further reduce the variability introduced by trypsin digestion and to improve the traceability of test results to reach the desirable analytical performance for clinical chemistry application.

Role of serum lipoprotein at the site of iloprost therapy in the treatment of painful bone marrow edema

The authors hypothesized that the emergence of painful bone marrow edema occurs through microembolisms in the bone marrow that may be reflected in elevated plasma parameters of hypofibrinolysis or a disturbance of the lipid metabolism and that treatment with iloprost may lead to a decrease in or normalization of the elevated serum parameters and, therefore, to pain reduction. Twenty-one patients (12 men and 9 women; mean age, 50 years [range, 22-70 years]) with painful bone marrow edema and elevated lipoprotein(a) (Lp[a]) serum values were treated with intravenous iloprost. Before and 6 weeks after iloprost therapy, the serum concentrations of Lp(a), apolipoprotein A1 (ApoA1), and apolipoprotein B (ApoB) were determined. At 6-week follow-up, 17 patients reported complete resolution of their symptoms. For these patients, complete bone marrow edema resolution was observed on magnetic resonance imaging. Four patients reported that their symptoms were either the same or had worsened but had partial bone marrow edema resolution on magnetic resonance imaging. In these patients, Lp(a) values either increased or remained the same. Hence, the total success rate of iloprost treatment was 86% at a mean follow-up of 17 months (range, 3-45 months). Before iloprost therapy, mean ApoA1, ApoB, and Lp(a) values were 159.8, 108.3, and 69.1 mg/dL, respectively. Six weeks after iloprost therapy, mean ApoA1, ApoB, and Lp(a) values decreased to 147.6 (P=.011), 98.4 (P=.042), and 38.3 (P<.001) mg/dL, respectively. The results of this study indicate a possible role of hypofibrinolysis or a disturbance in the lipid metabolism in the emergence of painful bone marrow edema.

Pioglitazone Randomised Italian Study on Metabolic Syndrome (PRISMA): effect of pioglitazone with metformin on HDL-C levels in Type 2 diabetic patients

BACKGROUND

Previous evidence indicates that pioglitazone may improve dyslipidemia in patients with Type 2 diabetes mellitus (T2DM).

AIM

The primary objective of this study was to evaluate the effect of either pioglitazone or placebo with metformin on levels of serum HDL cholesterol (HDL-C) in patients with T2DM. A secondary objective evaluated changes in metabolic syndrome (MS)-specific parameters.

SUBJECTS AND METHODS

This multicenter, double-blind, randomized study was performed in patients with T2DM treated with metformin and hemoglobin A1c (HbA1c) levels between 6-8%, central obesity and reduced HDL-C. MS was evaluated from global changes in parameter values and expressed as a single factorial score following multivariate analysis of each parameter. 213 patients (110 in the pioglitazone group and 103 in the placebo group) were available for intention-to-treat analysis.

RESULTS

Pioglitazone-treated patients showed a significant increase in HDL-C compared to placebo group (6.3 mg/dl vs 3.0 mg/dl; p<0.01) in addition to a greater reduction in the extent of MS (-13.2 vs -4.9; p=0.0055). Upon study completion, patients treated with pioglitazone had lower levels of HbA1c (6.41±0.65 vs 6.96±0.74%; p<0.001) and homeostasis model assessment-insulin resistance (HOMA-IR) (2.88±1.95 vs 4.68±3.63; p=0.013) and a reduction of the atherogenic LDL subfraction (pattern B) (-5.7%).

CONCLUSIONS

The beneficial effects observed in pioglitazone-treated patients in the present study, (i.e. the increase in HDL-C and the reduction of insulin resistance and atherogenic LDL subfractions), support findings from the PROactive trial, where pioglitazone showed pleiotropic effects and reduced death, fatal myocardial infarction (MI) and non-fatal MI in T2DM patients with MS. Furthermore, medication used in this study showed good tolerability.

Dyslipidemia and diabetic retinopathy

Diabetic retinopathy (DR) is one of the major microvascular complications of diabetes. In developed countries, it is the most common cause of preventable blindness in diabetic adults. Dyslipidemia, a major systemic disorder, is one of the most important risk factors for cardiovascular disease. Patients with diabetes have an increased risk of suffering from dyslipidemia concurrently. The aim of this article is to review the association between diabetic retinopathy (DR) and traditional/nontraditional lipid markers, possible mechanisms involving lipid metabolism and diabetic retinopathy, and the effect of lipid-lowering therapies on diabetic retinopathy. For traditional lipid markers, evidence is available that total cholesterol and low-density lipoprotein cholesterol are associated with the presence of hard exudates in patients with DR. The study of nontraditional lipid markers is advancing only in recently years. The severity of DR is inversely associated with apolipoprotein A1 (ApoA1), whereas ApoB and the ApoB-to-ApoA1 ratio are positively associated with DR. The role of lipid-lowering medication is to work as adjunctive therapy for better control of diabetes-related complications including DR.

Coagulation abnormalities in osteonecrosis and bone marrow edema syndrome

The aim of this review was to provide information about the variety of thrombophilic and hypofibrinolytic markers that are possible risk factors for the development of osteonecrosis and bone marrow edema syndrome. A total of 48 parameters were identified in 45 studies that included 2163 patients. The most frequently reported laboratory findings included altered serum concentrations of lipoproteins, decreased concentration and function of fibrinolytic agents, increased levels of thrombophilic markers, and several single nucleotide polymorphisms. Despite inhomogeneities in reported parameters, results, patients' collectives, and treatment strategies, these data suggest that coagulation abnormalities may play an important role in the emergence of osteonecrosis and bone marrow edema syndrome.

The value of apolipoprotein B/A1 ratio in the diagnosis of metabolic syndrome in a Korean population

OBJECTIVE

The ratio of apolipoprotein B (apoB) to apolipoprotein A1 (apoA1) has been reported to be associated with the metabolic syndrome (MetS). However, the optimal cut-off value of apoB/A1 ratio for detecting subjects with MetS has remained undetermined. In the present study, we aimed to investigate whether apoB/A1 ratio can be an indicator of MetS and to determine the optimal cut-off value of apoB/A1 ratio in detecting subjects with MetS in a Korean population.

DESIGN

This cross-sectional study was conducted at the Asan Medical Center, Seoul, Republic of Korea.

SUBJECTS AND MEASUREMENTS

We collected the data of 10,940 subjects who participated in a routine health screening examination regarding conventional risk factors and serum levels of apoB and apoA1.

RESULTS

The odds for MetS were significantly higher in the highest compared with the lowest apoB/A1 ratio quartiles, after adjustment for confounding variables, in both men [odds ratio (OR) = 4·07, 95% CI = 3·42-4·84] and women (OR = 8·41, 95% CI = 5·85-12·08). The optimal apoB/A1 ratio cut-off value for the detection of MetS was 0·65, which had a sensitivity of 63·5% and a specificity of 61·3% (area under the curve = 0·67, 95% CI = 0·66-0·68, P < 0·001) in men and 0·62, which had a sensitivity of 67·9% and a specificity of 61·9% (area under the curve = 0·70, 95% CI = 0·69-0·71, P < 0·001) in women.

CONCLUSIONS

These results suggest that apoB/A1 ratio is independently associated with MetS and that an apoB/A1 ratio >0·65 in men and 0·62 in women is a marker of MetS independent from conventional risk factors.

A confirmatory factor analysis of the metabolic syndrome in adolescents: an examination of sex and racial/ethnic differences

Objective

The metabolic syndrome (MetS) is a cluster of clinical indices that signals increased risk for cardiovascular disease and Type 2 diabetes. The diagnosis of MetS is typically based on cut-off points for various components, e.g. waist circumference and blood pressure. Because current MetS criteria result in racial/ethnic discrepancies, our goal was to use confirmatory factor analysis to delineate differential contributions to MetS by sub-group.

Research Design and Methods

Using 1999–2010 data from the National Health and Nutrition Examination Survey (NHANES), we performed a confirmatory factor analysis of a single MetS factor that allowed differential loadings across sex and race/ethnicity, resulting in a continuous MetS risk score that is sex and race/ethnicity-specific.

Results

Loadings to the MetS score differed by racial/ethnic and gender subgroup with respect to triglycerides and HDL-cholesterol. ROC-curve analysis revealed high area-under-the-curve concordance with MetS by traditional criteria (0.96), and with elevations in MetS-associated risk markers, including high-sensitivity C-reactive protein (0.71), uric acid (0.75) and fasting insulin (0.82). Using a cut off for this score derived from ROC-curve analysis, the MetS risk score exhibited increased sensitivity for predicting elevations in ≥2 of these risk markers as compared with traditional pediatric MetS criteria.

Conclusions

The equations from this sex- and race/ethnicity-specific analysis provide a clinically-accessible and interpretable continuous measure of MetS that can be used to identify children at higher risk for developing adult diseases related to MetS, who could then be targeted for intervention. These equations also provide a powerful new outcome for use in childhood obesity and MetS research.

Correlation between mesenteric fat thickness and serum apolipoproteins in patients with peripheral arterial occlusive disease

BACKGROUND

Visceral fat possesses the most detrimental potential for cardiovascular morbidity through the release of adipokines, as well as metabolic and proinflammatory mediators, which adversely affect metabolic and vascular homeostasis. Among the different types of visceral adipose tissue, mesenteric fat is considered particularly detrimental, due to its close proximity to the portal circulation, affecting directly the liver, which is the main regulator of body metabolic homeostasis. Mesenteric fat can be reliably estimated using abdominal ultrasonography, the only available imaging method able to depict individual mesenteric leaves. Aim of the present study was to investigate the correlation of mesenteric fat thickness (MFT) with serum apolipoprotein levels in patients undergoing digital subtraction angiography in a single center.

METHODS

35 male patients with peripheral arterial disease were examined. After careful examination of the periumbilical area, the mesenteric leaves were identified. The maximal distance between each pair of sequential leaves was measured, and the mean value of the three thickest leaves was determined as the mesenteric fat thickness. Six apolipoprotein fasting serum concentrations were measured using a Luminex proteomics platform (xMAP Multiplex immunoassay): apolipoprotein A-I (apoAI), apolipoprotein A-II (apoAII), apolipoprotein B (apoB), apolipoprotein C-II (apoCII), apolipoprotein C-III (apoCIII) and apolipoprotein E (apoE).

RESULTS

MFT correlated with apoAII and apoB serum concentrations. The correlations with apoAII and apoB remained significant following correction for BMI. No correlations were noted between MFT and serum apoAI, apoCII, apoCIII or apoE levels before or after adjustment for BMI.

CONCLUSIONS

Our study indicates that MFT is significantly correlated with the concentration of atherogenic low density lipoproteins particles, as well as with apoAII, a determinant of free fatty acids levels. No correlation was observed between mesenteric fat thickness and very low density lipoprotein or chylomicron particles concentration.

Determinants of ApoB, ApoA1, and the ApoB/ApoA1 ratio in healthy schoolgirls, prospectively studied from mean ages 10 to 19 years: the Cincinnati National Growth and Health Study

The objectives were to prospectively assess determinants of apolipoproteins B (ApoB), A1 (ApoA1), and the ApoB/ApoA1 ratio in 797 healthy black and white schoolgirls from mean ages 10 to 19. There was prospective 9-year follow-up, with measures of ApoB at mean ages 10, 12, 14, 16 and 19, ApoA1 at mean ages 12, 14, 16, and 19, and assessment of annual reports of delayed menstrual cyclicity (≥42 days) from ages 14 to 19. Studies of 402 black and 395 white healthy schoolgirls were done in public and private schools, in urban and suburban Cincinnati. Black girls had lower ApoB, higher ApoA1, and lower ApoB/ApoA1. SHBG at age 14 in white and black girls was inversely correlated with the ApoB/ApoA1. At age 19, ≥3 annual reports of menstrual delay ≥42 days and metabolic syndrome were associated with higher ApoB and a higher ApoB/ApoA1 ratio. From ages 14 to 19, BMI and TG were independently positively associated with ApoB. Menstrual cyclicity ≥42 days, metabolic syndrome, BMI, and TG were independently positively associated with ApoB/ApoA1 ratios, while black race was negatively associated. The atherogenic ApoB/ApoA1 ratio from ages 14 to 19 is lower in black girls, and positively associated with hyperandrogenism, menstrual cyclicity ≥42 days, BMI, TG, and the metabolic syndrome, facilitating an adolescent approach to primary prevention of cardiovascular disease.

Discrimination of ischemic and hemorrhagic strokes using a multiplexed, mass spectrometry-based assay for serum apolipoproteins coupled to multi-marker ROC algorithm

PURPOSE

Typically, apolipoproteins are individually measured in blood by immunoassay. In this report, we describe the development of a multiplexed selected reaction monitoring (SRM) based assay for a panel of apolipoproteins and its application to a clinical cohort of samples derived from acute stroke patients.

EXPERIMENTAL DESIGN

An SRM assay for a panel of nine apolipoproteins was developed on a triple quadrupole mass spectrometer. Quantitative data for each apolipoprotein were analyzed to determine expression ratio and receiver operating characteristic (ROC) values for ischemic versus hemorrhagic stroke.

RESULTS

The optimized SRM assay was used to interrogate a small cohort of well-characterized plasma samples obtained from patients with acute ischemic and hemorrhagic strokes. The ROC analyses demonstrated good classification power for several single apolipoproteins, most notably apoC-III and apoC-I. When a novel multi-marker ROC algorithm was applied, the ischemic versus hemorrhagic groups were best differentiated by a combination of apoC-III and apoA-I with an area under the curve (AUC) value of 0.92.

CONCLUSIONS AND CLINICAL RELEVANCE

This proof-of-concept study provides interesting and provocative data for distinguishing ischemic versus hemorrhage within first week of symptom onset. However, the observations are based on one cohort of patient samples and further confirmation will be required.

Current epidemiology of diabetic retinopathy and diabetic macular edema

With increasing global prevalence of diabetes, diabetic retinopathy (DR) is set to be the principle cause of vision impairment in many countries. DR affects a third of people with diabetes and the prevalence increases with duration of diabetes, hyperglycemia, and hypertension-the major risk factors for the onset and progression of DR. There are now increasing data on the epidemiology of diabetic macular edema (DME), an advanced complication of DR, with studies suggesting DME may affect up to 7 % of people with diabetes. The risk factors for DME are largely similar to DR, but dyslipidemia appears to play a more significant role. Early detection of DR and DME through screening programs and appropriate referral for therapy is important to preserve vision in individuals with diabetes. Future research is necessary to better understand the potential role of other risk factors such as apolipoproteins and genetic predisposition to shape public health programs.

Serum apolipoproteins are associated with systemic and retinal microvascular function in people with diabetes

Serum apolipoprotein (apo)AI and -B have been shown to be associated with diabetic retinopathy, but the underlying mechanisms are unclear. We investigated whether apoAI and apoB levels are associated with measures of systemic and retinal microvascular function in patients with diabetes. We recruited 224 diabetic patients (85 type 1 and 139 type 2) and assessed serum lipids and lipoproteins from fasting blood, skin responses to sodium nitroprusside (endothelium independent) and acetylcholine (ACh) (endothelium dependent) iontophoresis, flicker-light-induced retinal vasodilatation, and retinal vascular tortuosity. After adjustment for age and sex, every SD increase in apoAI level was associated with ACh-induced skin perfusion (mean change 1.27%; P < 0.001 for apoAI) and flicker-light retinal arteriolar vasodilatation (0.33%; P = 0.003) and was associated inversely with arteriolar tortuosity (-2.83 × 10(-5); P = 0.044). Each SD increase in apoB was associated with arteriolar tortuosity only (1.75 × 10(-5); P = 0.050). These associations, except for apoB, remained in multivariate models. Serum apoAI was associated with increased vasomotor responsiveness to ACh and flickering light and inversely related to retinal vessel tortuosity--a characteristic that has both structural and functional dimensions. These findings provide additional insights into the potential mechanisms of apos in the pathogenesis of diabetic retinopathy and other diabetic microvascular complications.

Estimation of plasma apolipoprotein B concentration using routinely measured lipid biochemical tests in apparently healthy Asian adults

Background

Increased low-density lipoprotein cholesterol (LDL) concentration is associated with increased risk of coronary heart disease (CHD) but a substantial risk of cardiovascular disease often remains after LDL concentrations have been treated to target. Apolipoprotein B (apo B) is the major apolipoprotein contained within atherogenic lipoproteins such as LDL, and apo B is a more reliable indicator of cardiovascular risk than LDL concentration.

Aim and methods

Our aim was to develop a formula for calculating apo B using lipid biochemistry measurements that are commonly available in clinical practice. We examined the clinical and laboratory data from 73,047 Koreans who underwent a medical health check that included apolipoprotein B concentration. The study sample was randomly divided into a training set for prediction model building and a validation set of equal size. Multivariable linear regression analysis was used to develop a prediction model equation for estimating apo B and to validate the developed model.

Results

The best results for estimating apo B were derived from an equation utilising LDL and triglyceride (TG) concentrations [ApoB = −33.12 + 0.675*LDL + 11.95*ln(tg)]. This equation predicted the apo B result with a concordance correlation coefficient (CCC and 95%CIs) = 0.936 (0.935,0.937)).

Conclusion

Our equation for predicting apo B concentrations from routine analytical lipid biochemistry provides a simple method for obtaining precise information about an important cardiovascular risk marker.

Treatment options for the management of hypertriglyceridemia: strategies based on the best-available evidence

A severe elevation in triglycerides (TG; ≥500 mg/dL) increases the risk for pancreatitis. TG levels ≥200 mg/dL are associated with a greater risk of atherosclerotic coronary heart disease (CHD). However, no outcomes trials exist to assess the efficacy of TG lowering for preventing pancreatitis in patients with severe hypertriglyceridemia. Similarly, no completed prospective outcomes trial exists to support or refute a reduction in CHD risk resulting from lipid-altering therapy in patients specifically selected for the presence of hypertriglyceridemia. This review examines the available evidence for the use of statins, omega-3 fatty acids, fibrates, and niacin in the management of hypertriglyceridemic patients. Results from CHD outcomes trials support statins as the first-line lipid-altering drug therapy to reduce CHD in hypercholesterolemic patients, and subgroup analyses suggest statins are efficacious in hypertriglyceridemic patients with fasting TG levels <500 mg/dL. Omega-3 fatty acids and fibrates are reasonable first drug options for patients with TG ≥500 mg/dL and often are used to lower TG levels with the objective of reducing pancreatitis risk, although a statin or niacin may also be reasonable options. Combination lipid drug therapy may be needed to achieve both low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol treatment goals for CHD prevention in patients with elevated TG levels, particularly those with TG ≥500 mg/dL. Additional clinical outcomes data are needed to provide a more evidence-based rationale for clinical lipid management of hypertriglyceridemic patients.

Apolipoproteins a-I and B as components of metabolic syndrome with respect to diabetes status: a factor analysis

BACKGROUND

The aim of the current study was to elucidate the clustering pattern of metabolic syndrome components along with apolipoproteins (Apo) A-I and B in diabetic and nondiabetic subjects.

METHODS

Factor analysis of conventional variables of metabolic syndrome [i.e., waist circumference, homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides (TG), high-density lipoprotein-cholesterol (HDL-C), and systolic blood pressure (SBP)] with or without addition of Apo A-I and B was performed on 567 and 327 diabetic and nondiabetic subjects, respectively. Thereafter, analyses were repeated after substitution of TG and HDL-C by the TG-to-HDL-C ratio (TG/HDL-C).

RESULTS

Regarding conventional variables of metabolic syndrome, one or two underlying factors were identified, depending on whether lipid measures were entered as two distinct variables or as a composite measure. Apolipoproteins were consistent with a one-factor structure model of metabolic syndrome and did not change the loading pattern remarkably in nondiabetics. TG and HDL-C tended to cluster with Apo B and A-I, respectively, in different models.

CONCLUSION

The current study confirms that addition of Apo A-I and B is consistent with the one-factor model of metabolic syndrome and does not modify the loading pattern remarkably in nondiabetic subjects.