Relation of plasma levels and composition of apolipoprotein B-containing lipoproteins to angiographically defined coronary artery disease in young patients with myocardial infarction

Uncontrolled hypertension in patients with type 2 diabetes: What are the correlates?

Suboptimal blood pressure (BP) control in patients with type 2 diabetes is associated with adverse micro‐ and macrovascular complications. This study aimed to investigate the predictors of uncontrolled hypertension in an Iranian population with type 2 diabetes. This is a cross‐sectional study of 2612 patients with type 2 diabetes, including 944 patients with hypertension. Controlled and uncontrolled hypertension were assessed. Multivariate logistic regression modeling was used to determined independent predictors of uncontrolled hypertension. Of 2612 patients with type 2 diabetes, 944 (36.1%) patients had hypertension. Of all patients with hypertension, 580 (61.4%) were still on monotherapy. Uncontrolled hypertension was detected in 536 participants (56.8%). Patients with uncontrolled hypertension had significantly higher body mass index (BMI) (29.8±4.8 vs. 28.6±4.6), waist circumference (99.11±10.95 vs. 96.68±10.92), pulse pressure (67.3±17.3 vs. 48.4±10.7), total cholesterol (177.1±45.5 vs. 164.3±40.5), non‐HDL cholesterol (133.0±43.5 vs. 120.1±38.7), triglycerides (175.7±80.3 vs. 157.4±76.7), and Atherogenic Index of Plasma (AIP) (0.57±0.23 vs. 0.52±0.24) (p < .05 for all of them) compared to patients with controlled hypertension. Multivariate logistic regression analysis revealed that uncontrolled hypertension was significantly associated with BMI (p = .001), pulse pressure (p = .001), total cholesterol (p = .006), and non‐HDL cholesterol (p = .009). In patients with triglycerides levels > 200 mg/dl non‐HDL cholesterol had a significant correlation with uncontrolled hypertension (OR = 4.635, CI95%:1.781–12.064, p = .002). In conclusion, BMI, pulse pressure, total cholesterol, and non‐HDL cholesterol are significant predictors of uncontrolled hypertension in patients with type 2 diabetes. Also, ineffective monotherapy, medical inertia and patients’ non‐compliance were other contributors to the uncontrolled hypertension.

Increased ABCA1 (ATP-Binding Cassette Transporter A1)-Specific Cholesterol Efflux Capacity in Schizophrenia

Objective:

Patients with schizophrenia have increased long-term mortality attributable to cardiovascular disease and commonly demonstrate features of mixed dyslipidemia with low HDL-C (high-density lipoprotein cholesterol). The removal of cholesterol from cells by HDL via specific ATP-binding cholesterol transporters is a major functional property of HDL, and its measurement as cholesterol efflux capacity (CEC) can predict cardiovascular risk. Whether HDL function is impaired in patients with schizophrenia is unknown.

Approach and Results:

We measured basal and ABCA1 (ATP-binding cassette transporter A1)- and ABCG1 (ATP-binding cassette transporter G1)-dependent CEC, comparing patients with schizophrenia with age- and sex-matched healthy controls, and related our findings to nuclear magnetic resonance analysis of lipoprotein subclasses. Total plasma cholesterol and LDL-C (low-density lipoprotein cholesterol) were comparable between healthy controls (n=51) and patients (n=120), but patients with schizophrenia had increased total plasma triglyceride, low HDL-C and apo (apolipoprotein) A-I concentrations. Nuclear magnetic resonance analysis indicated a marked (15-fold) increase in large triglyceride-rich lipoprotein particle concentration, increased small dense LDL particles, and fewer large HDL particles. Despite lower HDL-C concentration, basal CEC was 13.7±1.6% higher, ABCA1-specific efflux was 35.9±1.6% higher, and ABCG1 efflux not different, in patients versus controls. In patients with schizophrenia, ABCA1-specific efflux correlated with the abundance of small 7.8 nm HDL particles but not with serum plasminogen or triglyceride levels.

Conclusions:

Patients with schizophrenia have increased concentrations of atherogenic apoB-containing lipoproteins, decreased concentrations of large HDL particles, but enhanced ABCA1-mediated CEC. In this population, preventative strategies should focus on reducing atherogenic lipoproteins rather than increasing CEC.

Matrix Metalloproteinase-1 and -9 Promoter Polymorphisms and Endometrial Carcinoma Risk in a Japanese Population

OBJECTIVE

The matrix metalloproteinases (MMPs) are a family of zinc-dependent proteases that degrade all the components of the extracellular matrix (ECM). Several studies have demonstrated association between MMP gene polymorphisms and various cancers. The object of this study was to investigate whether the MMP-1 and MMP-9 gene promoter polymorphisms are associated with endometrial carcinomas in a Japanese population.

METHODS

We compared the allele frequencies and genotype distributions of each single nucleotide polymorphism in the promoter regions of MMP-1 (-1607 1G/2G) and MMP-9 (-1562 C/T) in 107 endometrial carcinoma cases and 213 controls using polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) analysis.

RESULTS

The allele frequencies of MMP-1 -1607 2G and MMP-9 -1562T were 64.0% and 10.7% in the cases and 70.0% and 16.7% in the controls, respectively. No significant differences in the allele frequencies or genotype distributions were found between cases and controls for the MMP-1 -1607 1G/2G polymorphism. However, a small but significant difference in the allele frequency of the MMP-9 -1562T allele was noted between cases and controls (P = .046; odds ratio [OR] = 1.01; 95% confidence interval [CI], 1.01 to 2.73). Stratification by histology revealed a significant difference in the frequency of the MMP-9 -1562T allele between endometrioid carcinoma cases (10.2%) and controls (P = .043; OR = 1.76; 95% CI, 1.02 to 3.03); we did not find a significant difference in the frequency of the MMP-9 -1562T allele between non-endometrioid carcinoma cases (13.2%) and controls.

CONCLUSION

These results suggest that the MMP-9 -1562 C/T polymorphism may be associated with susceptibility to endometrioid carcinoma in the Japanese population.

Evaluation of Methods for the Measurement of Low-Density Lipoprotein Cholesterol

A high concentration of low-density lipoprotein cholesterol (LDL-C) in plasma is one of the strongest risk factors for atherosclerotic cardiovascular disease and mortality. The most common approach to determining LDL-C in the clinical laboratory is the Friedewald calculation. There is an increased interest to improve the accuracy of LDL-C estimated by this equation. The expert panel convened by National Cholesterol Education Program has recommended the development of accurate direct methods to measure LDL-C. Several homogeneous and fully automated methods have been introduced in recent years that show improved precision and accuracy over earlier methods, especially the Friedewald calculation. Each of the atherogenic particles in plasma—very-low, intermediate-, and low-density lipoprotein—as well as lipoprotein (a), contain one molecule of apolipoprotein B (apoB) and thus, plasma total concentration of apoB reflects the number of atherogenic particles. Several studies suggested that the measurement of apoB could improve the prediction of risk of coronary artery disease. Thus, in addition to the newly developed direct assays, alternative calculation procedures have been proposed that also take into consideration total serum apoB concentration for the estimation of LDL-C and the presence of small, dense LDL particles. The new generation of homogenous methods for the measurement of LDL-C and the use of serum apoB concentration for the estimation of LDL-C can contribute to the accurate LDL-C determination.

Biomarkers of Metabolic Syndrome: Biochemical Background and Clinical Significance

Biomarkers of the metabolic syndrome are divided into four subgroups. Although dividing them in groups has some limitations, it can be used to draw some conclusions. In a first part, the dyslipidemias and markers of oxidative stress are discussed, while inflammatory markers and cardiometabolic biomarkers are reviewed in a second part. For most of them, the biochemical background and clinical significance are discussed, although here also a well-cut separation cannot always be made. Altered levels cannot always be claimed as the cause, risk, or consequence of the syndrome. Several factors are interrelated to each other and act in a concerted, antagonistic, synergistic, or modulating way. Most important conclusions are summarized at the end of every reviewed subgroup. Genetic biomarkers or influences of various food components on concentration levels are not included in this review article.

Metabolic alterations, HFE gene mutations and atherogenic lipoprotein modifications in patients with primary iron overload

HFE gene mutations contributed to a decrease of insulin secretion, an atherogenic LDL subfraction distribution and altered LDL and HDL particles in patients with iron overload. It remains to be determined whether these alterations contribute to cardiovascular risk.

New therapeutic alternatives for the management of dyslipidemia

Hypercholesterolemia affects over 34 million adults in the United States and is a major cause of coronary heart disease (CHD). Conventional therapies, such as statins, have demonstrated their ability to improve clinical end points and decrease morbidity and mortality in patients with CHD. Lomitapide (Juxtapid(®)), mipomersen (Kynamro(®)), and icosapent (Vascepa(®)) are 3 novel agents approved by the US Food and Drug Administration in the past 2 years, which offer new lipid-lowering treatment options with unique pharmacology.

Effect of Atorvastatin versus Simvastatin on Lipid Profile and Plasma Fibrinogen in Patients with Hypercholesterolaemia: A Pilot, Randomised, Double-Blind, Dose-Titrating Study

OBJECTIVE

To investigate the effect of atorvastatin vs simvastatin on lipid profile and plasma fibrinogen in patients with hypercholesterolaemia.

PATIENTS

30 outpatients (25 men), with a median age of 51 years were studied. Eight patients had established coronary artery disease (CAD) and four had diabetes mellitus at baseline. 11 patients presented a Frederickson's IIb phenotype and 19 a IIa phenotype at baseline.

STUDY DESIGN

After a 6-week placebo period, patients were randomly assigned to simvastatin (10 mg/day, n = 15) or atorvastatin (10 mg/day, n = 15). Lipid profile, apolipoproteins B and A-I and plasma fibrinogen were measured for a 16-week period, at 4-week intervals. Thereafter, the dose of each drug was doubled only in patients with low density lipoprotein cholesterol (LDL-C) levels above 130 mg/dl for a further 16-week period.

RESULTS

Ten of 15 patients on atorvastatin 10mg (66%) and four of 15 on simvastatin 10mg (27%) achieved the LDL-C <130 mg/dl goal. Apolipoprotein B was reduced by both drugs (-33%, p < 0.001 for atorvastatin and -18%, p < 0.05 for simvastatin), but plasma fibrinogen and triglyceride were reduced only by atorvastatin (-20%, p < 0.01; -36%, p < 0.001, respectively). During the second 16-week period seven of 11 patients receiving the simvastatin 20mg dose (64%) achieved the LDL-C <130 mg/dl goal. The comparison of atorvastatin 10mg with simvastatin 20mg showed that the drugs appear to be equipotent in terms of LDL-C lowering.

CONCLUSIONS

Atorvastatin in equipotent doses to simvastatin appeared to be more effective than the latter in reducing triglyceride and plasma fibrinogen in patients with hypercholesterolaemia, mainly in those with Frederickson's phenotype Iib.

Statin-fibrate combination for mixed dyslipidaemia: a limited option?

Abstract A growing body of evidence suggests that targeting low-density lipoprotein cholesterol is not enough and that a substantial residual risk remains despite aggressive statin treatment, particularly in patients with mixed dyslipidemia. Statin plus fibrate combination results in a more effective control of several lipid parameters than either monotherapy with a safety profile similar to both monotherapies. Therefore, this combination might represent a therapeutic option for selected patients with mixed dyslipidemia. However, the clinical benefit of statin/fibrate combination has only been observed in small subgroup analyses and more data are needed before a wider implementation is recommended in everyday clinical practice.

Evaluation of established coronary heart disease on the basis of HDL and non-HDL NMR lipid profiling

A (1)H NMR-based lipid profiling approach was used to investigate the prediction of coronary heart disease (CHD) and examine the confounding effect of factors such as gender, triglycerides, HDL-cholesterol and age levels on the prediction of disease. The HDL and non-HDL lipid profiles in 47 patients with triple vessel disease (TVD) and 41 patients with normal coronary arteries (NCA) both documented angiographically were generated. The presence of CHD was predicted with a sensitivity and specificity of 52% and 75% for HDL model and 78% and 80% for non-HDL, respectively. The lipid constituents of HDL lipoproteins which contributed to the separation between the two groups were the saturated fatty acids, cholesterol, total omega-3 fatty acids, degree of unsaturation, diallylic protons from polyunsaturated fatty acids, linoleic acid and, to a lesser extent, the number of fatty acids, triglycerides, unsaturated fatty acids and phosphatidylcholine. Respectively, for non-HDL, lipoproteins were the saturated fatty acids, number of fatty acids, cholesterol, unsaturated fatty acids and phosphatidylcholine. Gender, triglycerides, HDL-cholesterol and age influenced the lipid constituents of HDL and non-HDL lipoproteins that contributed to the separation between subgroups and confounded the predictive power of the models. NMR-based lipid profiling analysis could contribute to the identification of noninvasive markers for the presence and the development of the disease.

Evaluation of lipid profiles and the use of omega-3 essential Fatty Acid in professional football players

BACKGROUND

Recent research showed 82% of 233 retired National Football League players under age 50 had abnormal narrowing and blockages in arteries compared to the general population of the same age. It has been suggested that early screening and intervention in this at-risk population be a priority.

HYPOTHESIS

Omega-3 essential fatty acid has been shown to improve cardiovascular lipid risk factors and should improve lipid profiles in professional football players to help reduce their recently shown accelerated risk of developing cardiovascular disease.

METHODS

A total of 36 active national football players were randomly assigned to 2 groups: the first group (n = 20) was provided fish oil capsules (2200 mg of mixed docosahexaenoic acid and eicosapentaenoic acid and 360 mg of other omega-3s), and the second group (n = 16) served as controls during a 60-day trial. Vertical Auto Profile cholesterol tests directly measuring serum low-density lipoprotein, high-density lipoprotein, and other subfractions were performed. Compliance, side effects, and seafood consumption data were also collected. Baseline, midpoint, and poststudy blood work measured plasma docosahexaenoic acid and eicosapentaenoic acid.

RESULTS

Treatment increased high-density lipoprotein (average percent change: +25.96, control +14.16), decreased triglycerides treatment (-8.06, control +43.98), very low-density lipoprotein treatment (-13.98, control +23.18), intermediate density lipoprotein (-27.58, control +12.07), remnant lipoproteins (-23.86, control +8.33), and very low-density lipoprotein-3 (-17.10, control +7.77). An average increase of 106.67% for docosahexaenoic acid and 365.82% for eicosapentaenoic acid compared to control was also shown.

CONCLUSION

Omega-3 supplementation significantly improved the lipid profile of active players randomized to treatment. These results suggest that fish oil supplementation is an effective way to increase eicosapentaenoic acid and docosahexaenoic acid levels in plasma and should be considered as a method to improve modifiable cardiovascular risk lipid factors in professional football players.

CLINICAL RELEVANCE

A prospective study examining the effects of 60 days of a highly purified fish oil supplementation in professional football players.

Atherogenic lipoprotein particle size and concentrations and the effect of pravastatin in children with familial hypercholesterolemia

OBJECTIVE

To determine lipoprotein particle concentrations and size in children with familial hypercholesterolemia (FH) and investigate the effect of pravastatin therapy on these measures.

STUDY DESIGN

Lipoprotein particle concentrations and sizes were examined by nuclear magnetic resonance (NMR) spectroscopy in 144 children with FH and 45 unaffected siblings. The effect of pravastatin therapy (20 to 40 mg) on lipoprotein particle concentration and size were compared with placebo after 1 year of treatment, using analysis of covariance.

RESULTS

Compared with the unaffected siblings, the children with FH had significantly higher concentrations of very-low-density lipoprotein (VLDL) particles (115.6 nmol/L vs 51.2 nmol/L; P < .001) and low-density lipoprotein (LDL) particles (1726.8 nmol/L vs 955.3 nmol/L; P < .001), and lower concentrations of high-density lipoprotein (HDL) particles (23.2 micromol/L vs 26.9 micromol/L; P < .001). Compared with placebo, pravastatin therapy decreased the concentration of VLDL particles by 35.9 nmol/L (P < .001), of total LDL particles by 342.7 nmol/L (P < .001), of large LDL particles by 189.5 nmol/L (P < .001), and of small LDL particles by 156.2 nmol/L (P = .152), but increased the concentration of total HDL particles by 2.2 micromol/L (P < .001), of large HDL particles by 1.0 micromol/L (P = .006), and of medium HDL particles by 1.1 micromol/L (P = .003). VLDL particle size increased by 1.0 nm (P = .032).

CONCLUSIONS

Compared with their healthy siblings, children with FH have an atherogenic lipoprotein profile based on their lipoprotein distribution and lipoprotein particle diameter. Pravastatin therapy can improve, but not fully restore, these lipoprotein abnormalities toward normal levels in these children.

Gap analysis of pediatric reference intervals for risk biomarkers of cardiovascular disease and the metabolic syndrome

The childhood obesity epidemic has begun to compromise the health of the pediatric population by promoting premature development of atherosclerosis and the metabolic syndrome (MS), both of which significantly increase the risk of cardiovascular disease (CVD) early in life. As a result, recently, there has been increased recognition of the need to assess and closely monitor children and adolescents for risk factors of CVD and components of the MS. Serum/Plasma biomarkers including total cholesterol, triglycerides, HDL-C, LDL-C, insulin and C-peptide have been used for this purpose for many years. Recently, emerging biomarkers such as apolipoprotein AI, apolipoprotein B, leptin, adiponectin, free fatty acids, and ghrelin have been proposed as tools that provide valuable complementary information to that obtained from traditional biomarkers, if not more powerful predictions of risk. In order for biomarkers to be clinically useful in accurately diagnosing and treating disorders, age-specific reference intervals that account for differences in gender, pubertal stage, and ethnic origin are a necessity. Unfortunately, to date, many critical gaps exist in the reference interval database of most of the biomarkers that have been identified. This review contains a comprehensive gap analysis of the reference intervals for emerging and traditional risk biomarkers of CVD and the MS and discusses the clinical significance and analytical considerations of each biomarker.

Microsomal triglyceride transfer protein -493T variant reduces IDL plus LDL apoB production and the plasma concentration of large LDL particles

The microsomal triglyceride transfer protein (MTP) is essential for the synthesis and secretion of apolipoprotein B (apoB)-containing lipoproteins. We investigated the role the MTP -493G/T gene polymorphism in determining the apoB-100 secretion pattern and LDL heterogeneity in healthy human subjects. Groups of carriers of the T and the G variants (n = 6 each) were recruited from a cohort of healthy 50-yr-old men. Kinetic studies were performed by endogenous [(2)H(3)]leucine labeling of apoB and subsequent quantification of the stable isotope incorporation. apoB production rates, metabolic conversions, and eliminations were calculated by multicompartmental modeling (SAAM-II). LDL subfraction distribution was analyzed in the entire cohort (n = 377). Carriers of the MTP -493T allele had lower plasma LDL apoB and lower concentration of large LDL particles [LDL-I: 136 +/- 57 (TT) vs. 175 +/- 55 (GG) mg/l, P < 0.01]. Kinetic modeling suggested that MTP -493T homozygotes had a 60% lower direct production rate of intermediate-density lipoprotein (IDL) plus LDL compared with homozygotes for the G allele (P < 0.05). No differences were seen in production rates of large and small VLDL, nor were there any differences in metabolic conversion or elimination rates of apoB between the genotype groups. This study shows that a polymorphism in the MTP gene affects the spectrum of endogenous apoB-containing lipoprotein particles produced in humans. Reduced direct production of LDL plus IDL appears to be related to lower plasma concentrations of large LDL particles.

Common polymorphisms in the CYP7A1 gene do not contribute to variation in rates of bile acid synthesis and plasma LDL cholesterol concentration

Transcriptional regulation of the cholesterol 7alpha-hydroxylase (CYP7AI) gene is of critical importance for bile acid and cholesterol metabolism. We evaluated the physiological significance of two common polymorphisms (-203C/A and -469T/C) in the promoter region of the CYP7AI gene. No evidence was found for physiological differences between either the -203C and -203A alleles or the -469T and -469C alleles in transient transfection studies using native 834bp promoter constructs. Moreover, no association was observed between the CYP7AI promoter polymorphisms and the hepatic cholesterol 7alpha-hydroxylase activity and parameters of bile acid synthesis rates, as analyzed in subjects with gallstone disease. In addition, no relationships were found between the promoter polymorphisms and plasma LDL cholesterol concentration in association studies conducted in three different groups of middle-aged Swedish men. Finally, near complete allelic association was found between the two promoter polymorphisms and the IVS6+363G/A polymorphism at the 3' end of the CYP7AI gene (|D'|=0.98), indicating strong linkage disequilibrium across the whole CYP7AI gene. It is concluded that common polymorphisms of the CYP7A1 gene do not contribute to variation in cholesterol 7alpha-hydroxylase activity, rates of bile acid synthesis and plasma LDL cholesterol concentration in humans.

Effects of a moderate exercise session on postprandial lipoproteins, apolipoproteins and lipoprotein remnants in middle-aged men

Prior moderate exercise reduces postprandial triglyceride concentrations. Its effects on the concentrations, compositions and potential atherogenicity of lipoprotein subfractions were investigated in the present study. Twenty normoglycaemic middle-aged men each underwent two fat tolerance tests (blood taken fasting and for 8 h after a meal containing 80 g fat and 70 g carbohydrate). On the afternoon before one test, subjects performed a 90-min treadmill walk (exercise); no exercise was performed before the control test. Prior exercise significantly reduced postprandial concentrations of chylomicrons (Sf >400) by 28.6% (absolute reduction 14.6 mg dl(-1)), of large VLDL1 (Sf 60-400) by 34.4% (39.7 mg dl(-1)) and of small VLDL2 (Sf 20-60) by 23.0% (9.6 mg dl(-1)). Over 95% of VLDL1 and VLDL2 comprised apolipoprotein (apo) B100-containing particles. Exercise also reduced postprandial remnant-like lipoprotein cholesterol (by 35%) and triglyceride concentrations (by 29%). Postprandial apo CIII/apo B and apo E/apo B ratios in VLDL1 were lower following exercise. Postprandial cholesteryl ester/triglyceride ratios were lower in VLDL1 and VLDL2 and higher in HDL2 following exercise. These data suggest that the effect of prior moderate exercise on VLDL1 is quantitatively greater than its effect on chylomicrons and that, in addition to reducing lipoprotein concentrations, exercise induces compositional changes to lipoprotein species which are likely to influence their metabolism and atherogenicity.

Acute myocardial infarction in young patients: nutritional status and biochemical factors

PURPOSE

The aim of this study was to establish whether nutritional status and biochemical factors, C-reactive protein (CRP), serum amyloid A (SAA) protein, serum iron (Fe) and fibrinogen at admission were different in patients with acute myocardial infarction (AMI) at a young age (<40 years) vs. those with AMI at an older age (>60 years). We also investigated whether during the stay in the hospital, the increase in acute-phase reactants was different in young vs. older subjects, and if dyslipidemic aspects were different between the two groups.

METHODS

The study population consisted of 40 patients, all males with a mean age of 36.7+/-1.16 years, admitted to our facility with AMI. The control group included 40 patients, all males, mean age of 66.3+/-4.24 years, with AMI. CRP, SAA, Fe and fibrinogen were determined at admission to the hospital and daily for 7 days in the two groups of patients.

RESULTS

In young patients the median value of the highest levels were 6.2 mg/l (range 0.7-27.30) for CRP, 13.22 mg/l (range 0.7-130) for SAA, 420 mg/dl (range 76-840) for fibrinogen and 49.1 gamma/ml (range 14-102) for Fe levels. In the older patients, the median value of the highest levels were 5.9 mg/l (range 0.6-28.30) for CRP, 12.12 mg/l (range 0.9-280) for SAA, 480 mg/dl (range 60-780) for fibrinogen and 47.1 gamma/ml (range 12-94) for Fe levels.

CONCLUSIONS

In the present study, acute-phase reactants were quantitatively similar in young and old patients. On the contrary, nutritional status, homocysteine, LDL and triglycerides are significantly higher in young patients than in old patients.

Non-HDL cholesterol as a measure of atherosclerotic risk

Elevated triglyceride (TG) and low high-density lipoprotein cholesterol (HDL-C) levels, hallmarks of the atherogenic lipid profile found in the metabolic syndrome and type 2 diabetes, are commonly seen in Japanese patients with coronary heart disease (CHD). In the setting of mildly to moderately elevated plasma TG (150-500 mg/dl), very-low-density lipoprotein (VLDL) accumulates and so do high levels of atherogenic TG-rich, cholesterol-enriched remnant particles. Indeed, in hypertriglyceridemia, abnormalities are seen in the quantity and quality of all lipoprotein B-containing lipoproteins. Non-HDL-C (total cholesterol minus HDL-C) provides a convenient measure of the cholesterol content of all atherogenic lipoproteins, and thus incorporates the potential risk conferred by elevated levels of atherogenic TG-rich remnants that is additional to the risk associated with low-density lipoprotein cholesterol (LDL-C). Non-HDL-C level has been found to be a strong predictor of future cardiovascular risk among patients whether or not they exhibit symptoms of vascular disease, and was recently recommended as a secondary treatment target (after LDL-C) in patients with elevated TG by the National Cholesterol Education Program Adult Treatment Panel III. Adoption of this readily available measure to assess risk and response to treatment in patients with elevated TG would improve treatment of dyslipidemia in a substantial number at risk for CHD.

Quantification of major lipid classes in human triacylglycerol-rich lipoproteins by high-performance liquid chromatography with evaporative light-scattering detection

Triacylglycerol-rich lipoproteins (TRL), comprising chylomicrons (CM) and very-low-density lipoproteins (VLDL), have been associated with cardiovascular disease. The lipid class content in the remnant particles of these lipoproteins is a determinant for the accumulation of lipids in macrophages and their transformation into foam cells. We have optimized a method for the simultaneous determination of cholesteryl esters (CE), triacylglycerols (TG), free cholesterol (FC), monoacylglycerols (MG), and phospholipids (PL) by HPLC coupled to a light-scattering detector (ELSD). A diol column and a ternary gradient of hexane, 2-propanol, and methanol were applied to CM and VLDL of human origin (n = 10), with excellent precision in terms of repeatability of peak areas and retention times. All peaks were baseline resolved although the resolution of CE and TG was compromised for the sake of simplicity of the solvent gradient. The ELSD response was fitted to second-order equations, with correlation coefficients (r2) higher than 0.999 for a wide range of concentrations (0.25-10 microg of lipid injected). TG were the major lipid class detected in human TRL, accounting for 62% in CM obtained 2 h after the oil intake. In addition we recorded a depletion of TG and CE in CM obtained 2 h after the oil intake of about 60%. We conclude that the method reported here is suitable for a rapid and precise determination of lipid classes in human TRL and, therefore, may be a useful tool for investigations on the atherogenicity of these lipoproteins.

Fractional esterification rate of cholesterol and ratio of triglycerides to HDL-cholesterol are powerful predictors of positive findings on coronary angiography

BACKGROUND

We examined the predictive value of various clinical and biochemical markers for angiographically defined coronary artery disease (aCAD). Specifically, we assessed the value of the ratio of plasma triglyceride (TGs) to HDL-cholesterol (HDL-C) and the fractional esterification rate of cholesterol in plasma depleted of apolipoprotein B (apoB)-containing lipoproteins (FER(HDL)), a functional marker of HDL and LDL particle size.

METHODS

Patients (788 men and 320 women) undergoing coronary angiography were classified into groups with positive [aCAD(+)] and negative [aCAD(-)] findings. Patient age, body mass index, waist circumference, blood pressure (BP), medications, drinking, smoking, exercise habits, and plasma total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-unesterified cholesterol, HDL-C, TGs, FER(HDL), apoB, log(TG/HDL-C), and TC/HDL-C were assessed. Lipids and apoproteins were measured by standard laboratory procedures; FER(HDL) was determined by a radioassay.

RESULTS

Members of the aCAD(+) group were older and had a higher incidence of smoking and diabetes than those in the aCAD(-) group. The aCAD(+) group also had higher TG, apoB, FER(HDL), and log(TG/HDL-C) and lower HDL-C values. aCAD(+) women had greater waist circumference and higher plasma TC and TC/HDL-C. aCAD(+) men, but not women, had higher plasma LDL-C. In the multivariate logistic model, the significant predictors of the presence of aCAD(+) were FER(HDL), age, smoking, and diabetes. If only laboratory tests were included in the multivariate logistic model, FER(HDL) appeared as the sole predictor of aCAD(+). Log(TG/HDL-C) was an independent predictor when FER(HDL) was omitted from multivariate analysis.

CONCLUSIONS

FER(HDL) was the best laboratory predictor of the presence of coronary atherosclerotic lesions.

In vitro and in vivo lipolysis of plasma triglycerides increases the resistance to oxidative modification of low-density lipoproteins

BACKGROUND

The majority of studies on low-density lipoprotein (LDL) particle size and susceptibility to oxidative modification have been either descriptive or interventional, but there are few mechanistic studies.

MATERIALS AND METHODS

Effects of exhaustive in vitro and in vivo lipolysis of serum and plasma triglycerides, respectively, by lipoprotein lipase (LPL) were investigated in healthy normotriglyceridemic men. The LDL end-product of lipolysis of very low-density lipoprotein (VLDL) underwent compositional analysis, gradient gel electrophoresis and an assessment of resistance to copper-induced oxidative modification.

RESULTS

The LDL particle contents of free fatty acid and alpha-tocopherol increased, whereas the contents of free and esterified cholesterol, alpha-carotene and coenzyme Q10 decreased upon incubation of serum with LPL in vitro. The LDL particle size decreased and the resistance to the oxidative modification of LDL increased. Lipolysis of plasma triglycerides in vivo, achieved by intravenous injection of heparin, did not alter the LDL particle size but increased the resistance to the oxidative modification of LDL. This change was accompanied by an increase in the LDL particle content of alpha-tocopherol, whereas the free fatty acid content was unaltered.

CONCLUSIONS

The results show that the increased resistance to oxidative modification of LDL after lipolysis of plasma triglycerides was concomitant with an increased LDL particle content of alpha-tocopherol, and that free fatty acids did not seem to contribute to the increased resistance to oxidative modification of LDL in vivo. Furthermore, our data indicate that the resistance of LDL to oxidative modification is not dependent on particle size.

Effects of short- and long-term growth hormone replacement on lipoprotein composition and on very-low-density lipoprotein and low-density lipoprotein apolipoprotein B100 kinetics in growth hormone-deficient hypopituitary subjects

In this study, we concurrently examined the effects of 8 and 40 weeks of growth hormone replacement (GHR) on lipids, lipoprotein composition, low-density lipoprotein (LDL) size, very-low-density lipoprotein (VLDL) apolipoprotein (apo)B kinetics and LDL apoB kinetics. Eight weeks of GHR did not alter lipid profiles. Forty weeks of GHR increased high-density lipoprotein-cholesterol (HDL-C) concentration (P =.01), nonsignificantly reduced LDL-C (P =.06), and reduced the HDL/LDL-C ratio (P =.04). Forty weeks of GHR increased HDL free cholesterol (P =.03), total cholesterol (P =.01), and cholesterol ester (P <.01) concentrations. No other significant changes in VLDL, LDL, or HDL composition or LDL size were noted at any time. Eight weeks of GHR reduced VLDL apoB absolute secretion rate (ASR, P =.03), with nonsignificant reductions in fractional secretion rate (FSR, P =.09) and pool size (P =.09). After 40 weeks of GHR, the VLDL apoB ASR, FSR, and pool size were not significantly different from baseline. Forty weeks of GHR increased both LDL apoB FSR (P =.02) and LDL apoB ASR (P =.04), with a small decrease in pool size. Thus, GHR may have important antiatherogenic effects; HDL-C increased, LDL-C was nonsignificantly reduced, the total/HDL-C ratio was reduced, VLDL apoB production was reduced, and LDL apoB turnover was increased.

In vivo evidence for increased oxidation of circulating LDL in impaired glucose tolerance

Oxidized LDL (oxLDL) is a key mediator in atherogenesis and a marker of coronary artery disease (CAD). Type 2 diabetes is associated with excessive cardiovascular morbidity and mortality. Because atherogenesis starts before diabetes is diagnosed, we investigated whether circulating oxLDL levels are increased in impaired glucose tolerance (IGT). OxLDL levels were measured in 376 subjects with normal glucose tolerance (NGT), 113 patients with IGT, and 54 patients with newly diagnosed type 2 diabetes. After correction for age and BMI, serum levels of oxLDL were significantly increased in IGT versus NGT subjects (P = 0.002). OxLDL levels were not associated with the following parameters of the oxidative/antioxidative balance in the blood: total antioxidant capacity, urate-to-allantoin ratio, and circulating phagocyte oxygenation activity. In stepwise multivariate analysis, LDL cholesterol (P < 0.0005) and triglycerides (P < 0.0005) were the strongest predictors of circulating oxLDL levels, followed by HDL cholesterol (P = 0.003), 2-h postchallenge C-peptide (P = 0.011), fasting free fatty acids (P = 0.013), and serum paraoxonase activity (P = 0.035). The strong correlation of oxLDL with LDL cholesterol and triglycerides indicates that LDL oxidation in IGT is preferentially associated with dyslipidemia. OxLDL increase may explain the high atherogenic potency of dyslipidemia in the prediabetic state.

Insulin, insulin propeptides and intima-media thickness in the carotid artery in 58-year-old clinically healthy men. The Atherosclerosis and Insulin Resistance study (AIR)

AIMS

To examine the relationship between specific (intact) insulin, insulin propeptides and subclinical atherosclerosis.

METHODS

A cross-sectional study based on a stratified sampling of randomly selected, clinically healthy 58-year-old men (n = 391). Ultrasound examinations of the carotid arteries were performed with measurement of intima-media thickness (IMT) in the common carotid artery and in the carotid artery bulb. Fasting, cross-reacting plasma insulin (RIA), specific (intact) insulin, proinsulin, 32,33 split proinsulin and C-peptide were measured.

RESULTS

Plasma concentrations of cross-reacting plasma insulin, specific insulin, proinsulin, 32,33 split proinsulin and C-peptide were univariately associated with common carotid artery IMT. Established risk factors such as blood pressure, smoking, apoB, triglycerides, body mass index (BMI), and waist--hip ratio were also related to IMT. After adjustment for smoking, apoB, blood pressure and triglycerides, cross-reacting plasma insulin, proinsulin and C-peptide but not specific insulin and split 32,33 proinsulin remained associated with carotid artery IMT. No associations remained after adjustment for BMI.

CONCLUSIONS

Fasting plasma proinsulin, C-peptide, and insulin by cross-reacting RIA was associated with common carotid artery IMT independent of several conventional risk factors for atherosclerosis. The multicollinearity between the insulin peptides and propeptides makes it difficult to clarify the exact role of each peptide.

Determinants of the severity and extent of coronary artery disease in patients with type-2 diabetes and in nondiabetic subjects

BACKGROUND

Factors predicting the anatomic distribution and the severity and extent of coronary atherosclerosis in patients with clinically manifest coronary artery disease (CAD) for type-2 diabetic patients could be different than those for nondiabetic patients.

OBJECTIVE

To study the determinants of severity and extent of CAD in consecutive patients with type 2 diabetes mellitus, compared with those for matched nondiabetic patients, undergoing clinically indicated coronary angiography.

METHODS

Coronary angiograms of 48 men and seven women with type-2 diabetes and an equal number of nondiabetic subjects were analyzed quantitatively. Scores reflecting severity and extent of CAD were compared with potential risk factors using univariate correlation analyses and multivariate regression models.

RESULTS

For the diabetics, a global coronary atheroma burden index was independently and directly related to age (P = 0.022) and to level of intermediate-density lipoprotein cholesterol (P = 0.055), and inversely to level of particles of a subtype of high-density lipoprotein (P = 0.022). Several angiographic indexes were related to the duration of diabetes and control of glycemia. For the nondiabetic group, global atheroma burden was independently related to age (P = 0.028), a history of hypertension (P = 0.028), and concentration of low-density lipoprotein (P = 0.013), and inversely to level of apolipoprotein A-I (P = 0.008). The duration of coronary disease and a history of smoking were also predictive of severe coronary atherosclerosis among nondiabetic patients.

CONCLUSIONS

Classical risk factors are strong predictors of the severity and extent of coronary atherosclerosis in nondiabetic patients, but the most important determinants for type-2 diabetic patients are levels of triglyceride-rich lipoproteins and apolipoprotein A-I-containing particles of high-density lipoprotein, and factors directly related to diabetes.

Insulin resistance and intima-media thickness in the carotid and femoral arteries of clinically healthy 58-year-old men. The Atherosclerosis and Insulin Resistance Study (AIR)

OBJECTIVE

To examine whether insulin resistance was associated with ultrasound-assessed measures of atherosclerosis in men with varying degrees of obesity.

DESIGN

A random selection of subjects from the general population were divided into quintiles of a body mass index/blood glucose score that was shown to be a valid and reproducible index of the degree of insulin sensitivity as assessed by the clamp technique. Every fourth man in quintiles 1 and 5 and every 20th man in quintiles 2-4 (in total, 104 men) were selected for an ultrasound examination of the carotid and femoral arteries and a euglycaemic hyperinsulinaemic clamp examination, adjusted for fat-free mass.

SETTING

A university hospital.

SUBJECTS

A total of 104 clinically healthy 58-year-old men of Swedish ancestry.

RESULTS

The mean common carotid artery intima-media thickness (IMT), but not the common femoral IMT, correlated significantly with glucose infusion rate (GIR) (r = - 0.20, P < 0.05), systolic blood pressure (r = 0.20, P < 0.05), pulse pressure (r = 0.23 P < 0.01), heart rate (r = 0.20, P < 0.05), HDL cholesterol (r = - 0.18, P < 0.05), log triglycerides (r = 0.28, P < 0.01), apoA1 (r = - 0.20, P < 0.05), apoB (r = 0.21, P < 0.05), LDL particle size (r = - 0.22, P < 0.05) and plasma insulin (r = 0.20, P < 0.05). In a multiple regression, common carotid IMT was independently associated with log triglycerides (beta = 0.25, P = 0.012) and pulse pressure (beta = 0.21, P = 0.031) (R2 = 8.7%, P = 0.005)

CONCLUSIONS

Insulin sensitivity, measured with the gold standard euglycaemic hyperinsulinaemic clamp method, showed similar associations with ultrasound-assessed measures of atherosclerosis in the carotid arteries as established cardiovascular risk factors, but only triglycerides and pulse pressure contributed independently to the variability in the common carotid intima-media thickness.

LDL particle size in relation to intima-media thickness and plaque occurrence in the carotid and femoral arteries in patients with hypercholesterolaemia

OBJECTIVES

Small LDL particle size has been shown to be associated with coronary artery disease. However, no previous study has been performed relating LDL particle size to ultrasound measurement of atherosclerosis in hypercholesterolaemic subjects. The main aims of the present study were therefore: (i) to investigate the relationship between intima-media thickness (IMT) of the carotid bulb and LDL particle size in patients with primary hypercholesterolaemia (n = 102) and in matched normocholesterolaemic controls (n = 102); and (ii) to investigate the relationship between plaque occurrence in the carotid and femoral arteries and LDL particle size. LDL particle size was determined by subjecting serum to 2-16% polyacrylamide gradient gel electrophoresis.

RESULTS

The results showed that patients with primary hypercholesterolaemia had smaller LDL peak particle size compared with healthy control subjects (P < 0.001 for men, P = 0.006 for women). However, the difference in LDL peak particle size between patients with hypercholesterolaemia and controls disappeared when adjusting for serum triglycerides. There was no association between increasing IMT of the carotid bulb and decreasing LDL peak particle size or between the occurrence of moderate to large plaques in the carotid and femoral arteries and small LDL peak particle size. However, metabolic variables such as serum triglycerides, HDL, blood glucose, body mass index, and also systolic blood pressure were associated with LDL peak particle size.

CONCLUSION

The lack of an association between atherosclerosis, as measured by ultrasound, and small LDL particle size in patients with hypercholesterolaemia implies that other risk factors, such as hypercholesterolaemia and high blood pressure, may overshadow any importance of small LDL particle size.

Plasma lipoprotein particle concentrations in postmenopausal women with unstable coronary artery disease. Analysis of diagnostic accuracy using receiver operating characteristics

BACKGROUND

The contribution of plasma lipids to cardiovascular risk is usually evaluated by measuring plasma concentrations of total cholesterol, triglycerides and HDL cholesterol, and calculating LDL cholesterol concentration. We investigated plasma concentrations of apolipoproteins and lipoprotein particles in women with unstable coronary artery disease (CAD) to evaluate whether these, better than the routine lipid status, could differentiate women with and without coronary atherosclerosis.

METHODS

Blood samples for lipid analyses were collected from 119 angiographically examined postmenopausal 49-79-year-old women with unstable CAD, and from 101 age-matched controls. Mean plasma concentrations were compared and the discriminatory ability of the different variables were tested using receiver operating characteristics (ROC).

RESULTS

At coronary angiography 19% had normal vessels and 81% had coronary atherosclerosis. A disturbed triglyceride metabolism was the most pronounced lipid abnormality in women with unstable CAD and coronary atherosclerosis. ROC showed that none of the evaluated variables had a particularly high discriminatory power regarding unstable CAD or coronary atherosclerosis. The ratio cholesterol/HDL cholesterol was best with an ROC area of 0.79. Furthermore, the newer lipid variables, i.e. lipoprotein particles and apolipoproteins, were no better than the traditional variables.

CONCLUSION

Lipoprotein changes reflecting a disturbed triglyceride metabolism are most pronounced in women with unstable CAD and coronary atherosclerosis. Lipoprotein particles and apolipoproteins alone were no better than lipids and lipoproteins in separating women with from those without coronary atherosclerosis. Our study does not support the measurement of apolipoproteins and lipoprotein particles on the basis of diagnostic accuracy alone.

Postprandial lipoprotein metabolism and atherosclerosis

Postprandial lipids and lipoproteins have been associated with the presence of cardiovascular disease in a large number of case-control studies. Because the metabolic perturbations around the postprandial situation is a key driving force for cholesterol flux between lipoproteins and tissues, together with the augmented generation of potentially atherogenic cholesterol-rich remnant lipoproteins, several hypotheses have been formulated to link excessive lipoproteinaemic response to fat intake with cardiovascular disease. Recent information on the regulation of lipoprotein remnant formation and its relation to atherosclerosis will enable us to test a pertinent clinical question: is there a direct relationship between repeated elevations of postprandial lipoproteins and development of atherosclerosis?

Human lipoprotein lipase HindIII polymorphism in young patients with myocardial infarction

We investigated the possibility that the DNA HindIII polymorphism of human lipoprotein lipase (LPL) is associated with the severity of coronary artery disease (CAD) determined by angiography in young patients who survived a myocardial infarction (MI). Conflicting studies have explored the relationship linking CAD severity to the HindIII restriction site polymorphism at the LPL gene locus, and to our knowledge, no data are available from Italy. The patients were aged less than 45 years (mean age, 40.1 +/- 3.9 years); 83 were male and four were female. The 87 case-patients had a Q-wave or non-Q-wave infarction (67.3% and 32.7%, respectively); the MI was anterior (50.5%), lateral (41.7%), or inferior (7.8%). Analysis of coronary angiograms showed the absence of critical stenosis in 13.8% and the presence of monovessel disease in 50.6% and multivessel disease in 35.6% of the case-patients. The allelic frequency of the HindIII H(-) and H(+) allele was 0.37 and 0.63, respectively. There was a striking association between the HindIII polymorphism and the number of diseased vessels. The patients with HindIII(+/+) genotypes were significantly more likely to have double- or triple-vessel disease and less likely to have no significantly diseased vessels. In this study, we demonstrated that the homozygous form of the LPL HindIII(+) allele increases the risk of multivessel disease by a factor of 4 in an Italian group of young MI survivors. This association was independent from the smoking status and a positive family history for CAD and hypertension, which are known to predict CAD severity. The discrepancies in the results of these studies are difficult to explain. The lack of homogeneity in the study populations (age at which CAD occurred, number of enrolled patients, and geographical origin) and differences in the assessment of CAD severity may account for these conflicting results.

Myocardial infarction in young patients

Myocardial infarction in persons under the age of 45 years accounts for 6% to 10% of all myocardial infarctions in the United States. In this age group, it is predominantly a disease of men. Important risk factors include a family history of myocardial infarction before age 55 years, hyperlipidemia, smoking, and obesity. Unlike older patients, approximately half of young patients have single-vessel coronary disease, and in up to 20%, the cause is not related to atherosclerosis. Coronary angiography may be warranted in young patients with myocardial infarction to define the anatomy of the disease and to permit optimal management.

New concepts and paradigms in cardiovascular medicine: the noninvasive management of coronary artery disease

Coronary atherosclerosis is a diffuse heterogeneous process that occurs throughout the length of epicardial coronary arteries. Myocardial infarction and unstable coronary syndromes are caused most commonly by plaque rupture of lipid rich, less severe coronary artery stenoses. Vigorous cholesterol lowering by low fat food and lipid active drugs, control of hypertension, and smoking abstinence stabilize plaque and markedly reduce coronary events and angina pectoris with greater improvement in survival than reported for elective invasive revascularization procedures. The term "regression" or "reversal" of coronary artery disease (CAD) as used clinically incorporates the spectrum of beneficial changes in plaque composition and pathology, modest improvement in anatomic severity, endothelial healing, increased coronary flow and flow capacity, decreased symptoms, and improved survival. Standard coronary arteriography and standard noninvasive diagnostic tests (as commonly used) are inadequate for identifying or assessing severity of diffuse CAD. Newer technology or approaches using noninvasive positron emission tomography (PET), invasive intravascular ultrasound or pressure or flow velocity guide wires provide important new insights into the presence and severity of both segmental and diffuse CAD. Revascularization procedures may be beneficial in selected, restricted circumstances, primarily for 3-vessel disease and reduced left ventricular function and for "hibernating" or "stunned" myocardium. However, the benefits of revascularization procedures on survival in patients with good left ventricular function have not been convincingly documented, with substantive evidence that adverse outcomes outweigh the potential benefits. This collective new knowledge provides the basis for a shift in the management of CAD from an invasive, procedure-oriented viewpoint currently dominant in cardiology toward a noninvasive orientation that views the problem as a graded, continuous, heterogeneously diffuse disease process for which reversal treatment is optimal. Noninvasive management of CAD based on reversal treatment is a valid, safe, effective primary step, but it requires patient and physician knowledge. CAD should be treated immediately at the time of a firm diagnosis by simultaneous, vigorous risk factor management, low fat diet and a statin class drug. For control of high-density lipoprotein and triglycerides, other lipid active drugs should be added or substituted for statins if side effects prevent their use. Low fat food and weight control by appropriate caloric carbohydrate restriction are essential for reducing the highly atherogenic postprandial lipid surge that is not affected by statins. This vigorous reversal treatment, with aggressive anti-anginal and anti-platelet management as needed, should be used in every patient with diagnosed CAD before elective revascularization procedures are considered. In the author's experience, the majority of patients will pursue an effective reversal regimen when it is presented and managed appropriately with strong support by a knowledgeable participating physician providing sustained, intense guidance and pharmacologic control. For the minority of patients not responding to vigorous medical treatment or demonstrating progression, coronary arteriography and revascularization procedures are then appropriate.

Evidence for a role of tumor necrosis factor alpha in disturbances of triglyceride and glucose metabolism predisposing to coronary heart disease

Elevated plasma levels of triglyceride-rich lipoproteins, a decreased high-density lipoprotein (HDL) cholesterol concentration, hyperinsulinemia, and impaired fibrinolytic function frequently aggregate in patients with premature coronary heart disease (CHD). Experimental studies suggest that the cytokine tumor necrosis factor alpha (TNFalpha) produced by adipocytes plays a part in the regulation of triglyceride and glucose metabolism. The present study examined whether TNFalpha is implicated in these metabolic and fibrinolytic disturbances in young postinfarction patients. TNFalpha levels were determined in two groups of young (age <45 years) male postinfarction patients (n = 92 and 60) and in matched, population-based control subjects (n = 63). Plasma TNFalpha was higher in patients than in controls (4.1 +/- 1.6 v2.5 +/- 0.4 pg/mL, P < .0001). In hyperlipidemic patients, TNFalpha levels correlated significantly with the concentrations of very-low-density lipoprotein (VLDL) triglyceride and cholesterol and negatively with HDL cholesterol. Treatment with bezafibrate decreased VLDL triglycerides and increased HDL cholesterol, but did not affect TNFalpha levels. The TNFalpha concentration also correlated significantly with fasting glucose and proinsulin concentrations, as well as glucose and proinsulin levels after glucose ingestion. In contrast, no relations were found with the insulin level or degree of insulin resistance. The present results provide clinical evidence for a basic role of TNFalpha in hypertriglyceridemia, glucose intolerance, and the etiology of premature CHD.

Insulin resistance is not a major determinant of low-density lipoprotein particle size

The relationship between low-density lipoprotein (LDL) peak particle diameter and insulin sensitivity, very-low-density lipoprotein (VLDL) + intermediate-density lipoprotein (LDL) triglyceride, cholesterol, and apoprotein B, postprandial lipemia, and LDL + high-density lipoprotein (HDL) triglyceride was assessed. The subjects were 101 healthy males aged 15 to 45 years. Sixty-one subjects (60.4%) were offspring of a parent with coronary artery disease before age 60, and 40 subjects (39.6%) had no parental history of coronary artery disease. LDL peak particle diameter was measured following polyacrylamide gradient gel electrophoresis. An insulin sensitivity index (Si) was determined from a frequently sampled intravenous glucose tolerance test using a minimal modeling method. A fat tolerance test was performed with a test meal containing 70 g/m2 fat, with triglyceride concentrations measured hourly for 12 hours. LDL peak particle diameter was significantly correlated with body mass index (BMI) (r = -.282, P < .01), waist to hip ratio (r = -.291, P < .01), fasting triglyceride (logarithmically [log] transformed) (r = -.566, P < .001), area under the postprandial triglyceride curve (log transformed) (r = -.562, P < .001), VLDL + IDL triglyceride (log transformed) (r = -.462, P < .001), VLDL + IDL cholesterol (log transformed) (r = -.477, P < .001), VLDL + IDL apoprotein B (log transformed) (r = -.321, P < .001), LDL + HDL triglyceride (log transformed) (r = .583, P < .001), and HDL cholesterol (r = .347, P < .001), but there was no significant correlation with Si. Using stepwise regression analysis, LDL + HDL triglyceride showed the strongest relationship to LDL peak particle diameter, accounting for 34% of the variation in size. Si was not an independent predictor of LDL particle size. In conclusion, insulin sensitivity appears to have little influence on LDL particle size. The importance of LDL + HDL triglyceride should be considered a preliminary finding warranting verification in this and other populations.

Safety and efficacy of long-term statin-fibrate combinations in patients with refractory familial combined hyperlipidemia

No monotherapy is able to tackle effectively all atherogenic features of familial combined hyperlipidemia: high low-density lipoprotein (LDL) cholesterol, triglycerides (TG), and plasma fibrinogen, as well as low high-density lipoprotein (HDL) cholesterol. The present study investigated the safety and efficacy of combined pravastotin or simvastatin with gemfibrozil or ciprofibrate treatment on total cholesterol, LDL, TG, plasma fibrinogen, and apoproteins B and A-I in patients with refractory familial combined hyperlipidemia, with or without coronary artery disease. From the initial 420 patients included in the study, 389 (294 men and 95 women, mean age 51 years [range 30 to 65]) completed the study. These patients were followed for a mean period of 29 months (1 year [n = 107], 2 years [n = 102], 3 years [n = 95], and 4 years [n = 85]). Patients given a hypolipidemic diet were randomly assigned to pravastatin + gemfibrozil (n = 135, 20 and 1,200 mg/day, respectively), simvastatin + gemfibrozil (n = 130, 20 and 1,200 mg), or simvastotin + ciprofibrate (n = 124, 20 and 100 mg). Lipid parameters, apoproteins B and A-I, and plasma fibrinogen were assessed every 3 months. Physical and laboratory investigations for adverse effects were performed every month for the first 3 months and every 3 months thereafter. No patient exhibited myopathy or rhabdomyolysis. Five patients (1.3%) were withdrawn from the study because of high transaminases (more than threefold the upper normal limit). Five nonfatal coronary artery disease events were recorded. All 3 combination treatments were more effective in normalizing lipid profile than any monotherapy in the past. Simvastatin + ciprofibrate was more effective than pravastatin + gemfibrozil in reducing LDL, TG, and plasma fibrinogen levels. Simvastatin + gemfibrozil increased HDL levels more than the other 2. The apoprotein B decrease was analogous to the LDL reduction by all combinations, whereas apoprotein A-I was increased more with simvastatin + gemfibrozil. The data suggest that the statin-fibrate combinations used in the study are safe and have a favorable effect on all major coronary artery disease risk factors in patients with refractory familial combined hyperlipidemia with or without coronary artery disease. Early detection of the rare drug-induced reversible hepatotoxicity calls for close monitoring of patients.

Low-density lipoprotein particle size is not a discriminating marker for atherogenic risk in male offspring of parents with early coronary artery disease

The aim of this study was to assess the importance of low-density lipoprotein (LDL) particle size as a marker of atherogenic risk in male offspring of a parent with early coronary artery disease (CAD) before the age of 60 years. CAD-positive (CAD+) offspring were recruited into two groups based on age, 15 to 30 years (n = 20) and 31 to 45 years (n = 41), and matched to CAD-negative (CAD-) offspring by age and body mass index (BMI) (n = 20 and 21 per group). LDL peak particle diameter was assessed by polyacrylamide gradient gel electrophoresis. There was no significant difference in LDL peak particle diameter between CAD+ and CAD- offspring (26.2 +/- 0.1 v 26.2 +/- 0.1 nm, mean +/- SE). There was also no difference between CAD+ offspring and CAD- offspring when comparisons were made within their own age group (26.5 +/- 0.1 nm in younger CAD+ offspring v 26.2 +/- 0.1 nm in younger CAD- offspring, and 26.0 +/- 0.1 nm in older CAD+ offspring v 26.1 +/- 0.2 nm in older CAD- offspring). Peak particle diameter was significantly greater in younger CAD+ offspring than in older CAD+ offspring (26.5 +/- 0.1 v 26.0 +/- 0.1 nm, P < .05). We conclude that small LDL particle size is not a discriminating marker for early atherogenic risk, and that measurement of LDL particle size has limited value in the assessment of coronary risk, at least in the age ranges we studied.

High-density lipoprotein: relations to metabolic parameters and severity of coronary artery disease

The regulation of plasma high-density lipoprotein (HDL) cholesterol level by the joint influence of plasma lipoprotein lipids, lipoprotein lipase (LPL), hepatic lipase (HL), cholesteryl ester transfer protein (CETP), oral glucose tolerance, and postload plasma insulin and proinsulin levels was investigated in young postinfarction patients and healthy population-based control subjects. In addition, the association between HDL cholesterol and the number and severity of coronary stenoses previously reported in this cohort of young postinfarction patients was further investigated by analyzing the determinants and angiographic relations of HDL subclasses measured by gradient gel electrophoresis. The following parameters showed significant univariate relations with HDL cholesterol level in the patient group: very-low-density lipoprotein (VLDL) cholesterol and triglyceride, low-density lipoprotein (LDL) triglyceride, and postload plasma insulin concentrations, preheparin plasma LPL mass, and postheparin plasma HL activity. In the control group, significant correlations with HDL cholesterol concentration in addition to those noted among the patients were found for body mass index (BMI), LDL cholesterol level, postload plasma intact proinsulin concentration, and LPL activity in postheparin plasma. In contrast to the patients, no significant relations were noted for postload plasma insulin level and preheparin plasma LPL mass. Multiple stepwise regression analysis showed that 42% of the variability of HDL cholesterol in the patients could be accounted for by VLDL cholesterol concentration (29%), LDL triglyceride level (7%), and postheparin plasma HL activity (8%), whereas the corresponding figure in controls was 35% (VLDL cholesterol concentration [9%] and postheparin plasma HL activity [26%]. The strength of the relationships of HDL cholesterol and HDL subclasses to the coronary stenosis score was similar and statistically significant (r = .25 to .36). When the metabolic parameters that correlated with HDL cholesterol and HDL subclass concentrations in univariate analysis were used as covariates, all relations to the coronary stenosis score disappeared. This clearly indicates that the influence of triglyceride-rich lipoproteins and lipolytic enzymes needs to be considered when assessing the association between HDL cholesterol and coronary artery disease (CAD).

Cost-effective treatment of coronary artery disease--the new imperative

Large lipid-lowering clinical trials have demonstrated a significant reduction in cardiovascular events and the need for cardiovascular procedures. These clinical and point trials used relatively weak treatment modalities, and when the cost savings of the reduced number of events is balanced against the estimated cost of treatment, the average difference is approximately $1,500 per patient per year. Arteriographic trials have used similar or more aggressive lipoprotein therapy over shorter periods of time. Estimates of cost savings from reduced clinical events balanced against the cost of treatment in these studies indicate a wide spectrum of estimated patient costs. These estimates range between a cost of $2,273 per patient per year to a cost savings of (-)$901 per patient per year. Extrapolation to the United States population with coronary artery disease (CAD) suggests that greater than one billion dollars per year could be saved if patients with CAD received similar treatment and responded in a similar manner.

Triglyceride enriched lipoprotein particles correlate with the severity of coronary artery disease

A group of 100 male normotensive, non-obese, non-diabetic subjects who had undergone coronary angiography were studied to determine relationship between the severity of coronary artery disease (CAD) and plasma lipids, apolipoproteins and lipoprotein particles defined by their apolipoprotein composition. CAD was found in 84 and no measurable lesions were found in 26 subjects. The severity of CAD was determined on the basis of size and number of lesions and expressed in terms of a global CAD score. Low density lipoprotein (LDL)-cholesterol showed a tendency to be higher in CAD patients than in CAD-free subjects (216 vs. 205 mg/dl, P = 0.07). HDL-cholesterol showed a tendency towards lower values in CAD patients compared to CAD-free subjects 35 vs. 41 mg/dl, P = 0.07). In univariate analysis the severity of CAD correlated with (i) complex, apolipoprotein (apo) B containing particles (Lp-B-complex, r = 0.31, P = 0.005), (ii) HDL-cholesterol (r = -0.30, P = 0.005), (iii) apoC-III in heparin precipitate (r = 0.30, P = 0.005) and (iv) plasma triglycerides (r = 0.25, P = 0.02), all of which are related to triglyceride-rich lipoproteins. A comparison between the two subspecies of complex lipoprotein particles revealed that those containing apolipoproteins B, C-III and E (Lp-B:C:E complex) were more closely associated with CAD score (r = 0.27, P = 0.01) than those containing apolipoproteins A-II, B, C, D and E (Lp-A-II:B-complex). LDL-cholesterol also correlated with the global CAD score (r = 0.23, P = 0.03). In multiple regression analysis only HDL-cholesterol (P = 0.003), apoC-III-ratio (P = 0.007), Lp-B-complex (P = 0.02) and Lp-B:C:E-complex (P = 0.04) showed significant correlation with CAD score. The results of this study demonstrate that some of the triglyceride rich lipoprotein particles represent a risk factor for CAD and support the clinical usefulness of specific assays capable of distinguishing lipoprotein particles on the basis of apolipoprotein composition.