Apo B versus cholesterol in estimating cardiovascular risk and in guiding therapy: report of the thirty-person/ten-country panel

Low-density lipoprotein lowering in type 2 diabetes mellitus: how to know how low to go

PURPOSE OF REVIEW

Getting low-density lipoprotein to the right level in patients with type 2 diabetes should be relatively easy, given the potent pharmacological therapy that is available and the fact that low-density lipoprotein C is typically normal in these patients. Getting it right means getting the target for therapy right, however. The article examines the criteria that should be used to make this choice.

RECENT FINDINGS

In comparing different parameters, three criteria, in particular, need to be taken into account: the on-treatment predictive value of any parameter; the value relative to the population of one parameter compared with another, namely which is more deviant from the norm; and the concurrent level of high-density lipoprotein. The evidence from the low-density lipoprotein-lowering trials indicates that low-density lipoprotein C is not nearly as good as non-high-density lipoprotein C as a guide for the adequacy of low-density lipoprotein lowering, or, better still, apoB, with the apoB/apoA-I ratio being clearly the best of all.

SUMMARY

The evidence from the major clinical trials indicates the best single index of the adequacy of low-density lipoprotein lowering is the apoB/apoA-I ratio. Clinical practice should adapt to clinical evidence and, therefore, guidelines should be based on apolipoproteins rather than the conventional cholesterol indices.

High-density lipoprotein associations with coronary heart disease: Does measurement of cholesterol content give the best result?

The protective role played by high-density lipoprotein (HDL) in atherogenesis is well-accepted, as is the significant inverse association of HDL cholesterol (HDL-C) with coronary heart disease (CHD) risk. What remains controversial is whether we are using the best measure(s) of HDL to identify and manage HDL-related cardiovascular risk. Measuring particle number has been postulated to offer additional and possibly more specific information regarding risk. Although HDL-C is thought to indicate the quantity of circulating HDL particles, it is underappreciated that the amount of cholesterol carried inside lipoprotein particles is highly variable among individuals with the same HDL-C. Numerous trials have investigated the relations of CHD with various measures of HDL other than those based on cholesterol content of the particles present. Studies regarding the association of alternate measures of HDL with CHD risk have been mixed, possibly due to diversity in clinical characteristics accompanying low HDL-C states, variability in cholesterol content of HDL particles, and substantial inter-correlations of HDL with other lipoprotein particles. Additional research is needed to assess the clinical settings in which individual HDL tests, after multivariate adjustment for confounding factors, provide superior independent prediction of CHD events beyond HDL-C. Such studies show promise in defining measures of particle number that will prove useful in future strategies to enhance management of CHD risk and assess response to therapy at an individual patient level.

Value of Low-Density Lipoprotein Particle Number and Size as Predictors of Coronary Artery Disease in Apparently Healthy Men and Women

OBJECTIVES

We assessed relations of low-density lipoprotein (LDL) particle number (LDL-P) and LDL particle size as measured by nuclear magnetic resonance spectroscopy with LDL cholesterol (LDL-C) and the risk of future coronary artery disease (CAD).

BACKGROUND

Whereas LDL-C is an established risk factor for CAD, its discriminative power is limited. Measuring LDL-P and size may have stronger associations with CAD than LDL-C.

METHODS

A nested case-control study was performed in the prospective EPIC (European Prospective Investigation into Cancer and Nutrition)-Norfolk study, which comprises 25,663 subjects. Cases (n = 1,003) were individuals who developed CAD during 6 year follow-up. Control subjects (n = 1,885) were matched for age, gender, and enrollment time. Odds ratios (ORs) for future CAD were calculated, and we also evaluated whether LDL-P could improve the Framingham risk score (FRS) to predict CAD.

RESULTS

In univariate analyses, LDL-P (OR 2.00, 95% confidence interval [CI] 1.58 to 2.59) and non-high-density lipoprotein cholesterol (non-HDL-C) (OR 2.14, 95% CI 1.69 to 2.69) were more closely associated with CAD than LDL-C (OR 1.73, 95% CI 1.37 to 2.18). The additional value of LDL-P was lost after adjustment for HDL-C and triglyceride levels. Whereas LDL size was inversely related to CAD (OR 0.60, 95% CI 0.47 to 0.76), this relation was abolished upon adjustment for LDL-P. In a model adjusted for the FRS, LDL-P retained its association with CAD (p for trend 0.02).

CONCLUSIONS

In this large study of individuals with moderately elevated LDL-C, LDL-P was related to CAD on top of FRS as well as after adjusting for LDL-C. The additional value of LDL-P was comparable to non-HDL-C, and it was abolished after adjusting for triglycerides and HDL-C.

Effect of rosuvastatin 5-20mg on triglycerides and other lipid parameters in Japanese patients with hypertriglyceridemia

To evaluate the potential dose effect of rosuvastatin on triglyceride (TG) levels in Japanese hypertriglyceridemic patients, we randomized 154 patients with TG levels of >or=200 and <800 mg/dL to 8 weeks of treatment with rosuvastatin 5, 10 or 20mg once daily; bezafibrate 200mg twice daily; or placebo. Compared with placebo, TG was reduced by 30.1% with rosuvastatin 5mg, 30.1% with 10mg and 32.3% with 20mg (all p<or=0.0001), with no evidence of a dose effect. Changes in TG were evident after 2 weeks of treatment and maintained thereafter. In a benchmark comparison, rosuvastatin across its dose range reduced TG by 29.1-31.1% from baseline versus 45.4% for bezafibrate. Compared with bezafibrate, rosuvastatin was superior with respect to changes in non-high-density lipoprotein cholesterol (non-HDL-C, -36.8 to -44.3% for rosuvastatin versus -2.0% for bezafibrate), low-density lipoprotein cholesterol (-31.9 to -41.0% versus +29.3%), total cholesterol (-27.1 to -33.3% versus +2.1%), although smaller improvements in HDL-C (12.4-16.7% versus 19.6%) were observed. Rosuvastatin also produced superior dose-related decreases in median high-sensitivity C-reactive protein (22.9-38.5%). Treatment was well tolerated in both rosuvastatin and bezafibrate patients, with clinically important increases in alanine aminotransferase being rare, no adverse effect on renal function being observed and no cases of myopathy or rhabdomyolysis being reported. The current study does not suggest a dose-related effect of rosuvastatin in lowering TG in hypertriglyceridemic Japanese patients, although dose-related improvements in other elements of the atherogenic lipid profile were observed.

Proteomic analysis of proteins differentially expressed in preeclamptic trophoblasts

AIMS

To identify differential trophoblastic proteins associated with preeclampsia (PE) by proteomic analysis.

METHODS

We isolated and purified placental trophoblasts from normotensive pregnant women and patients with PE by a continuous Percoll gradient. The expression of proteins was determined by sliver staining after two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Proteins of interest were identified using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS).

RESULTS

The overall trophoblastic protein expression patterns in preeclamptic and corresponding normotensive placentas were quite similar except for some areas. Of 34 differentially expressed protein spots (p < 0.05 by paired t-test), seven differential proteins from nine spots were identified by MALDI-TOF-MS. The expression of the following proteins was repressed (p < 0.01): disulfide isomerase ER-60, peroxiredoxin 2, and Delta3,5-Delta2,4-dienoyl-CoA isomerase. Four proteins (protein disulfide isomerase precursor, endoplasmic reticulum resident protein, dihydrolipoyl dehydrogenase and TIM21-like protein) were found to be significantly upregulated in PE (p < 0.01).

CONCLUSION

We identified several proteins with significant altered expression in PE using 2D-PAGE. This method is a powerful technique with which to search for not only quantitative but also qualitative changes in a biological process of interest.

Differential impact of plasma triglycerides on HDL-cholesterol and HDL-apo A-I in a large cohort

OBJECTIVES

To examine the relationship between plasma triglycerides (TG) to HDL-cholesterol (HDL-C) or HDL apo A-I.

DESIGN AND METHODS

Bivariate and multiple linear regression analyses in a large cohort of 1886 subjects.

RESULTS

Higher plasma TG levels were associated with lower concentrations of both HDL-C and HDL-apo A-I. However, the HDL-C/HDL-apo A-I ratio was inversely correlated with plasma TG indicating that the overall composition of the HDL changed as plasma TG changed. Plasma TG levels contributed to 15.9% of the variance of the HDL-C/HDL-apo A-I ratio, whereas gender, HDL-TG, LDL-TG, body mass index and plasma apo B levels represented between 0.15% and 2.21% of this variance.

CONCLUSIONS

These results indicate that increasing levels of plasma TG result in greater reduction in HDL-C levels than in HDL-apo A-I and this might explain, at least in part, the differences that have been observed in the magnitude of the association of HDL-C versus HDL-apo A-I with the risk of cardiovascular disease.

Heterogeneity of low-density lipoprotein particle number in patients with type 2 diabetes mellitus and low-density lipoprotein cholesterol <100 mg/dl

Patients with type 2 diabetes mellitus have an increased risk of cardiovascular events even when treated to low-density lipoprotein (LDL) cholesterol goals. The purpose of this study was to determine how many diabetic patients with low LDL cholesterol have correspondingly low numbers of LDL particles (LDL-P) and the extent to which those achieving target levels of LDL cholesterol and non-high-density lipoprotein (HDL) cholesterol might still harbor residual risk associated with increased LDL-P. Split-sample measurements of LDL cholesterol, non-HDL cholesterol, and nuclear magnetic resonance measured LDL-P were performed on plasma samples from 2,355 patients with type 2 diabetes seen in clinical practice and who had LDL cholesterol levels <100 mg/dl. Substantial heterogeneity of LDL-P was noted among patients with low or very low levels of LDL cholesterol. Of 1,484 patients with low LDL cholesterol (70 to 99 mg/dl), only 385 (25.9%) had low levels of LDL-P (<20th percentile of an ethnically diverse contemporary reference population), whereas 468 (31.6%) had LDL-P values >50th percentile (>1,300 nmol/L). Among the 871 patients with very low LDL cholesterol, i.e., <70 mg/dl, 349 (40.1%) had LDL-P levels >1,000 nmol/L (>20th percentile) and 91 (10.4%) had LDL-P levels >50th percentile. For patients with high triglyceride values (200 to 400 mg/dl), there was less discordance between LDL-P and non-HDL cholesterol than between LDL-P and LDL cholesterol. However, for those with triglyceride levels <200 mg/dl, LDL-P distributions were similarly wide for patients having achieved low or very low targets of LDL cholesterol or non-HDL cholesterol. In conclusion, these data demonstrate that patients with type 2 diabetes mellitus and LDL cholesterol levels <100 mg/dl are extremely heterogeneous with regard to LDL-P and, by inference, LDL-based cardiovascular risk.

Quantification of serum apolipoprotein B by infrared spectroscopy

While the conventional approach to assessing both the risk of coronary artery disease and the adequacy of therapy is LDL cholesterol testing, there is compelling evidence to suggest that apolipoprotein B (apoB) is superior to LDL cholesterol for both of these purposes. However, the measurement of apoB requires techniques that can be expensive and difficult to standardize. The aim of this study was, therefore, to develop a new method, based on infrared (IR) spectroscopy, for the routine quantification of apoB in human serum. A total of 366 serum samples were obtained from patients with various disorders. Small volumes (2 microl) of serum specimens were dried to films, and duplicate IR absorption spectra measured. The reference apoB concentrations were determined separately using a standard method, and the proposed IR method was then calibrated using partial least squares (PLS) regression analysis to quantitatively correlate the IR spectra with the reference results. The apoB concentrations predicted from the IR spectra of serum were highly correlated and in excellent agreement with those determined by the reference method. The correlation coefficient (r) for apoB was 0.94, with the standard error between IR-predicted and reference values was 0.10 g/L. In combination with earlier work demonstrating the accurate determination of LDL-C, HDL-C, total cholesterol, and triglycerides from a single infrared spectroscopic measurement, the addition of accurate apoB determination from the same spectrum makes the method very attractive for laboratory use in the routine evaluation of coronary artery disease risk.

Canadian Cardiovascular Society position statement--recommendations for the diagnosis and treatment of dyslipidemia and prevention of cardiovascular disease

Since the last publication of the recommendations for the management and treatment of dyslipidemia, new clinical trial data have emerged that support a more vigorous approach to lipid lowering in specific patient groups. The decision was made to update the lipid guidelines in collaboration with the Canadian Cardiovascular Society. A systematic electronic search of medical literature for original research consisting of blinded, randomized controlled trials was performed. Meta-analyses of studies of the efficacy and safety of lipid-lowering therapies, and of the predictive value of established and emerging risk factors were also reviewed. All recommendations are evidence-based, and have been reviewed in detail by primary and secondary review panels. Major changes include a lower low-density lipoprotein cholesterol (LDL-C) treatment target (lower than 2.0 mmol/L) for high-risk patients, a slightly higher intervention point for the initiation of drug therapy in most low-risk individuals (LDL-C of 5.0 mmol/L or a total cholesterol to high-density lipoprotein cholesterol ratio of 6.0) and recommendations regarding additional investigations of potential use in the further evaluation of coronary artery disease risk in subjects in the moderate-risk category.

Apolipoprotein B as a long-term predictor of mortality in type 1 diabetes mellitus: a 15-year follow up

OBJECTIVES

To evaluate the association of apolipoprotein B (apo B) with mortality due to all causes, to cardiac disease and to ischaemic heart disease (IHD) in subjects with type 1 diabetes mellitus.

SUBJECTS

165 subjects with type 1 diabetes included in the Swiss Cohort of the WHO Multinational Study of Vascular Disease in Diabetes were followed for 14.7+/-0.45 years.

METHODS

Causes of death were obtained from death certificates, hospital records and postmortem reports. Using a parametric proportional hazards model the association of apo B with mortality rates was assessed by time-to-event analysis, including the absolute cumulative mortality risk over time for various apo B levels at baseline.

RESULTS

Apo B was positively associated with all-cause mortality [hazard ratio (HR) 2.65 per g L-1 increase of apo B, 95% CI: 1.11-6.36, P=0.029], cardiac mortality (HR 11.64, 1.03-131.11, P=0.047) and IHD mortality (HR 9.36, 1.26-69.66, P=0.029). An apo B>or=0.96 g L-1 translated into a duplication of overall mortality hazard (HR 1.93, 1.00-3.72, P=0.050), and a sevenfold increase of mortality because of cardiac disease or IHD (HR 7.44, 1.44-38.42, P=0.017 and HR 7.38, 0.78-69.82, P=0.081). A baseline apo B of 1.5 g L-1 predicted an absolute cumulative risk to die over the next 10 years of 12.1% (5.2-31.7) for male and of 10.4% (4.7-26.1) for female subjects whereas risks were 6.3% (1.8-21.4) and 5.4% (0.8-15.8) for an apo B of 0.8 g L-1.

CONCLUSION

Apo B is consistently associated with an increased mortality in type 1 diabetes.

Body composition and the apoB/apoA-I ratio in migrant Asian Indians and white Caucasians in Canada

Migrant and native South Asians appear to be at increased risk of Type II diabetes mellitus and coronary disease. The aim of the present study was to determine the relationship between the most accurate summary index of the lipoprotein-related risk of vascular disease, the apoB (apolipoprotein B-100)/apoA-I (apolipoprotein A-I) ratio, and body composition in established migrant South Asians and white Caucasians living in Canada. Men and women living in Montreal, Canada between the ages of 20–60 years were recruited for participation in the study. Subjects were excluded if they had a history of cardiovascular disease or were taking lipid-lowering medication. Individuals identified themselves as Asian Indian or Caucasian. Anthropometric measurements were collected, including weight, height, waist circumference, hip circumference and body fat percentage. Plasma samples were analysed for total cholesterol, HDL-C (high-density lipoprotein-cholesterol), apoA-I and apoB. Indian subjects had a substantially higher WHR (waist-to-hip ratio) than Caucasian subjects [men, 0.93±0.01 compared with 0.86±0.01 respectively (P<0.001); women, 0.88±0.01 compared with 0.77±0.01 respectively (P<0.0001)]. WHR correlated strongly with body fat percentage in Caucasians (men, r=0.63, P=0.0002; women, r=0.74, P<0.0001). By contrast, there was no correlation in Indians (men, r=0.22, P value not significant; women, r=0.23, P value not significant). In addition, Indian men and women had a higher apoB/A-I ratio than Caucasians [men, 0.85±0.04 compared with 0.66±0.04 respectively (P=0.001); women, 0.73±0.04 compared with 0.56±0.03 respectively (P=0.0003)]. Of interest, there were also significant correlations between the apoB/apoA-I ratio and WHR in all of the groups, except the Indian women, which were stronger than the correlation of the apoB/apoA-I ratio with BMI. On the other hand, there was no significant relationship between the apoB/apoA-I ratio and the body fat percentage in any of the groups. In conclusion, the present study confirms that, as body fat percentage increases, the distribution of body fat differs between migrant Indians and Caucasians living in Canada. It also relates differences in body fat distribution to differences in the apoB/apoA-I ratio, providing at least part of the answer as to why South Asians may be at increased risk of vascular disease.

Low-density lipoprotein cholesterol estimation by the Anandaraja's formula--confirmation

The number of the indirect methods for LDL-C estimation is growing. Our result support the reliability of new Anandaraja's formula for low-density lipoprotein estimation from total cholesterol and triglycerides.

Low carbohydrate diets improve atherogenic dyslipidemia even in the absence of weight loss

Because of its effect on insulin, carbohydrate restriction is one of the obvious dietary choices for weight reduction and diabetes. Such interventions generally lead to higher levels of dietary fat than official recommendations and have long been criticized because of potential effects on cardiovascular risk although many literature reports have shown that they are actually protective even in the absence of weight loss. A recent report of Krauss et al. (AJCN, 2006) separates the effects of weight loss and carbohydrate restriction. They clearly confirm that carbohydrate restriction leads to an improvement in atherogenic lipid states in the absence of weight loss or in the presence of higher saturated fat. In distinction, low fat diets seem to require weight loss for effective improvement in atherogenic dyslipidemia.

The apoB/apoA-I ratio: a strong, new risk factor for cardiovascular disease and a target for lipid-lowering therapy--a review of the evidence

During the last several years interest has focused on the importance of the lipid-transporting apolipoproteins--apoB transports all potentially atherogenic very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL) and LDL particles, and apoA-I transports and acts as the major antiatherogenic protein in the HDL particles. The evidence for the apoB/apoA-I ratio being a strong, new risk factor for cardiovascular (CV) disease and a target for lipid-lowering therapy is reviewed. Results from clinical prospective studies and lipid-lowering trials in healthy subjects and in patients with different clinical manifestations of atherosclerosis are reported. Risk of nonfatal and fatal myocardial infarction and stroke, and manifestations of atherosclerosis documented by angiographic, ultrasound and other techniques has been related to conventional lipids and apolipoproteins (apo). The cholesterol balance determined as the apoB/apoA-I ratio has repeatedly been shown to be a better marker than lipids, lipoproteins and lipid ratios. The results indicate that the apoB/apoA-I ratio is a simple, accurate and new risk factor for CV disease--the lower the apoB/apoA-I ratio, the lower is the risk. Guidelines should be developed in order to recognize the important clinical risk information embedded in the apoB/apoA-I ratio.