Atorvastatin treatment beneficially alters the lipoprotein profile and increases low-density lipoprotein particle diameter in patients with combined dyslipidemia and impaired fasting glucose/type 2 diabetes

Diabetic dyslipidemia is featured by hypertriglyceridemia, low high-density lipoprotein (HDL) cholesterol levels, and elevated low-density lipoprotein (LDL) cholesterol commonly in the form of small, dense LDL particles. First-line treatment, fibrates versus statins or both, of dyslipidemia in diabetic patients has been the focus of debate. We investigated the potential hypolipidemic effects of atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor with good triglyceride lowering properties, in patients with combined dyslipidemia and evidence of impaired fasting glucose or type 2 diabetes. Twenty patients were recruited for the study, and after a 60-day wash out period, baseline measurements of lipoprotein parameters, LDL particle diameter, and apolipoprotein B (apoB) degradation fragments were obtained. The group was then randomized, in a double-blinded manner, into 2 subgroups. Group A received atorvastatin (80 mg) and group B received placebo daily for 60 days. After the first treatment period, all patients were reanalyzed for the above parameters. The treatment regime then crossed over for the second treatment period in which group A received placebo and group B received atorvastatin (80 mg) daily for 60 days. All parameters were remeasured at the end of the study. Treatment with atorvastatin resulted in a statistically significant reduction in total cholesterol (41%), LDL cholesterol (55%), triglycerides (TG) (32%), and apoB (40%). Mean LDL particle diameter significantly increased from 25.29 +/- 0.24 nm (small, dense LDL subclass) to 26.51 < 0.18 nm (intermediate LDL subclass) after treatment with atorvastatin (n = 20, P <.005). At baseline, LDL particles were predominantly found in the small, dense subclass; atorvastatin treatment resulted in a shift in the profile to the larger and more buoyant LDL subclass. Atorvastatin treatment did not produce consistent changes in the appearance of apoB degradation fragments in plasma. Our results suggest that atorvastatin beneficially alters the atherogenic lipid profile in these patients and significantly decreases the density of LDL particles produced resulting in a shift from small, dense LDL to more buoyant and less atherogenic particles.     

Dose-dependent action of atorvastatin in type IIB hyperlipidemia: preferential and progressive reduction of atherogenic apoB-containing lipoprotein subclasses (VLDL-2, IDL,small dense LDL) and stimulation of cellular cholesterol efflux

Type IIB hyperlipidemia is associated with premature vascular disease, an atherogenic lipoprotein phenotype characterised by elevated levels of triglyceride-rich VLDL and small dense LDL, together with subnormal levels of HDL. The dose-dependent and independent effects of a potent HMGCoA reductase inhibitor, Atorvastatin, at daily doses of 10 and 40 mg, were evaluated on triglyceride-rich lipoprotein subclasses (VLDL-1, VLDL-2 and IDL), on the major LDL subclasses (light LDL, LDL-1+LDL-2, D: 1.019-1.029 g/ml; intermediate LDL, LDL-3, D: 1.029-1.039 g/ml and small dense LDL, LDL-4+LDL+5, D: 1.039-1.063 g/ml), on CETP-mediated cholesteryl ester transfer from HDL to apoB-containing lipoproteins, on phospholipid transfer protein activity and on plasma-mediated cellular cholesterol efflux in patients (n=10) displaying type IIB hyperlipidemia. Plasma concentrations of triglyceride-rich lipoprotein subclasses (TRL: VLDL-1, Sf 60-400; VLDL-2, Sf 20-60 and IDL, Sf 12-20) and of LDL (D: 1.019-1.063 g/ml) were markedly diminished after 6 weeks of statin treatment at 10 mg per day (-31 and -36%, respectively; P<0.002) and by 42 and 51%, respectively at the 40 mg per day dose. Increasing doses of atorvastatin progressively normalised both the quantitative and qualitative features of the LDL subclass profile, in which dense LDL predominated at baseline. Indeed, dense LDL levels were reduced by up to 57% at the 40-mg dose, leading to a shift in the peak of the density profile towards larger, buoyant LDL particles typical of normolipidemic subjects. In addition, marked reduction in numbers of apoB100-containing particle acceptors led to a 30% decrease (P<0.02) in CETP-mediated CE transfer from HDL. Finally, a significant dose-dependent statin-mediated elevation (+15% at 10 mg; P=0.0003 and +35% at 40 mg; P<0.0001 compared to baseline) in the capacity of plasma from type IIB subjects to mediate free cholesterol efflux from Fu5AH hepatoma cells was observed. Moreover, atorvastatin (40 mg per day) significantly increased plasma apoAI levels (+24%; P<0.05), thereby suggesting that this statin enhances production of apoAI and with it, formation of nascent pre-beta HDL particles. Plasma PLTP activity was not affected by either dose of atorvastatin. We conclude that increasing the dose of atorvastatin leads to dose-dependent, preferential and progressive reduction in particle numbers of atherogenic VLDL-2, IDL and dense LDL, and concomitantly, to enhanced cellular cholesterol efflux in type IIB dyslipidemia, thereby diminishing the atherosclerotic burden in subjects characterised by high cardiovascular risk.     

An increased number of very-low-density lipoprotein particles is strongly associated with coronary heart disease in Japanese men,independently of intermediate-density lipoprotein or low-density lipoprotein

BACKGROUND: Japanese patients with coronary heart disease (CHD) usually have slightly elevated triglyceride levels but virtually normal low-density lipoprotein (LDL)-cholesterol levels. DESIGN: Case-control study. METHODS: To explore the atherogenecity of mild hypertriglyceridemia, we measured very-low-density lipoprotein (VLDL) composition and apolipoprotein (apo) B in VLDL, intermediate-density lipoprotein (IDL), light LDL and dense LDL fractions separated by ultracentrifugation in 61 men with angiographically proven CHD and in 69 men without CHD. Apo B, E, C1 and C3 in VLDL were measured by enzyme-linked immunosorbent assay. RESULTS: Although total- and LDL-cholesterol levels were similar in CHD and control participants, triglyceride levels were significantly higher and high-density lipoprotein (HDL)-cholesterol levels were lower in CHD patients. Triglyceride, cholesterol and apo C1 and E levels in VLDL were two-fold higher and VLDL-apo B level was three-fold higher in CHD than control patients. IDL-triglyceride levels were significantly elevated in CHD, but IDL-cholesterol level was not. Apo B levels of the dense LDL fraction were significantly elevated in CHD groups, but those of the light LDL fraction were not. These differences were constant when triglyceride levels matched between both groups. Multiple logistic regression analysis revealed that the VLDL-apo B and VLDL-apo C1 levels were significantly associated with the incidence of CHD independent of the plasma triglyceride, HDL-cholesterol or apo B levels in dense LDL. CONCLUSION: These results suggest that an increased number of VLDL particles is strongly associated with CHD, independently of traditional risk factors or newly recognized atherogenic lipoproteins, such as IDL or small, dense LDL, in Japanese men.     

Controlling lipid levels in diabetes

Coronary heart disease (CHD) is associated with a 2- to 4-times greater risk of morbidity and mortality in patients with type 2 diabetes than in non-diabetic individuals. Dyslipidaemia is an important CHD risk factor in diabetic patients. The key atherogenic features of diabetic dyslipidemia are elevated levels of serum triglycerides, low levels of high density lipoprotein (HDL) cholesterol, and the preponderance of small, dense low density lipoprotein (LDL). As a result, treatment guidelines for diabetic dyslipidaemia recommend elevated LDL cholesterol and triglyceride levels and low HDL cholesterol levels as targets of therapy. Unfortunately, however, these lipid abnormalities often persist dispite best efforts to control hyperglycaemia, improve diet, and increase physical exercise, and therefore demand specific therapeutic intervention. Statins are the first choice for LDL cholesterol lowering as they are effective and well tolerated, and do not have adverse effects on glycaemic control. Furthermore, recent evidence suggests that statins may also be employed to treat moderately elevated levels of triglycerides. An increasing number of primary and secondary prevention trials have shown that lipid-lowering therapy with statins can significantly reduce the risk of CHD events in patients with diabetic dyslipidaemia.     

Qualitative effect of fenofibrate and quantitative effect of atorvastatin on LDL profile in combined hyperlipidemia with dense LDL.

INTRODUCTION: The association of elevated plasma triglyceride concentrations, decreased HDL-cholesterol, and dense LDL (dLDL) is referred to as the atherogenic lipoprotein phenotype. dLDL particularly plays a role in the metabolic syndrome and type 2 diabetes and may be one of the factors responsible for the increased risk for coronary artery disease in these patients. The effect of fenofibrate and atorvastatin on the LDL subfraction profile in patients with combined hyperlipidemia and a preponderance of dLDL was studied in a sequential design. METHODS: Six male patients with combined hyperlipidemia and dLDL received 160 mg/die supra-bioavailable fenofibrate. After a washout phase of 8 weeks all patients received 10 mg/die atorvastatin for another 8 weeks. At baseline, after fenofibrate, and after atorvastatin treatment LDL subfractions were analyzed by equilibrium density gradient ultracentrifugation. RESULTS: Treatment with atorvastatin and fenofibrate reduced serum cholesterol by 30 % and 21 % (p = 0.046) (p-values for differences between treatment groups), triglycerides by 32 % and 45 %, LDL cholesterol by 28 % and 16 %, and increased HDL cholesterol by 3 % and 6 %, respectively. Atorvastatin and fenofibrate treatment resulted in the following changes of apoB and LDL subfractions: LDL-1 (1.019 - 1.031 kg/L) - 31 % and + 15 % (p = 0.028); LDL-2 (1.031 - 1.034 kg/L) - 14 % and + 57 % (p = 0.028); LDL-3 (1.034 - 1.037 kg/L) - 20 % and + 30 % (p = 0.028); LDL-4 (1.037 - 1.040 kg/L) - 25 % and - 6 %; LDL-5 (1.040 - 1.044 kg/L) - 29 % and - 38 %; and LDL-6 (1.044 - 1.063 kg/L) - 39 % and - 55 % (p = 0.028). As a consequence, fenofibrate reduced LDL density significantly (p = 0.028 versus atorvastatin). CONCLUSIONS: Atorvastatin decreased all LDL-subfractions to a similar extent (quantitative effect) whereas fenofibrate reduced predominantly dLDL and changed the LDL profile towards medium dense LDL-particles (qualitative effect). Since medium dense LDL have a higher affinity to the LDL-receptor fenofibrate may have a higher antiatherogenic potential than assessed by the reduction of total LDL-cholesterol and triglycerides alone.     

The small, dense LDL phenotype and the risk of coronary heart disease: epidemiology, patho-physiology and therapeutic aspects.

More than decade ago, several cross-sectional studies have reported differences in LDL particle size, density and composition between coronary heart disease (CHD) patients and healthy controls. Three recent prospective, nested case-control studies have since confirmed that the presence of small, dense LDL particles was associated with more than a three-fold increase in the risk of CHD. The small, dense LDL phenotype rarely occurs as an isolated disorder. It is most frequently accompanied by hypertriglyceridemia, reduced HDL cholesterol levels, abdominal obesity, insulin resistance and by a series of other metabolic alterations predictive of an impaired endothelial function and increased susceptibility to thrombosis. Whether or not the small, dense LDL phenotype should be considered an independent CHD risk factor remains to be clearly established. The cluster of metabolic abnormalities associated with small, dense LDL particles has been referred to as the insulin resistance-dyslipidemic phenotype of abdominal obesity. Results from the Québec Cardiovascular Study have indicated that individuals displaying three of the numerous features of insulin resistance (elevated plasma insulin and apolipoprotein B concentrations and small, dense LDL particles) showed a remarkable increase in CHD risk. Our data suggest that the increased risk of CHD associated with having small, dense LDL particles may be modulated to a significant extent by the presence/absence of insulin resistance, abdominal obesity and increased LDL particle concentration. We suggest that the complex interactions among the metabolic alterations of the insulin resistance syndrome should be considered when evaluating the risk of CHD associated with the small, dense LDL phenotype. From a therapeutic standpoint, the treatment of this condition should not only aim at reducing plasma triglyceride levels, but also at improving all features of the insulin resistance syndrome, for which body weight loss and mobilization of abdominal fat appear as key elements. Finally, interventions leading to reduction in fasting triglyceride levels will increase LDL particle size and contribute to reduce CHD risk, particularly if plasma apolipoprotein B concentration (as a surrogate of the number of atherogenic particles) is also reduced.     

The role of non-LDL:non-HDL particles in atherosclerosis

Elevated concentrations of circulating apolipoprotein B (apoB)-containing lipoproteins, other than low-density lipoprotein (LDL), have been implicated as causative agents for the development of atherosclerosis. A form of dyslipidemia, the atherogenic lipoprotein profile, that consists of elevated intermediate-density lipoprotein (IDL), triglycerides (TGs), dense LDL and dense very low density lipoprotein (VLDL), and low high density lipoprotein-2, occurs in 40% to 50% of patients with coronary artery disease (CAD). The recently released Adult Treatment Panel III guidelines suggest that because elevated TGs are an independent CAD risk factor, some TG-rich lipoproteins, commonly called remnant lipoproteins, must be atherogenic. Relevant to this series on diabetes, a number of studies have shown that in type 2 diabetes, the severity of CAD is positively related to the numbers of TG-rich particles in the plasma. Although less clear, other studies in type 2 diabetes suggest that elevated levels of lipoprotein (a) [Lp(a)] may also be independently associated with CAD. In this article, we summarize evidence for the role of apoB-containing lipoprotein particles other than LDL in the development of atherosclerosis and discuss methods of quantification and possible pharmacologic interventions for lowering their plasma concentrations. The particles reviewed include the TG-rich lipoproteins: VLDL and its remnants, chylomicron remnants and IDL, and the C-rich lipoprotein: Lp(a).     

Action of atorvastatin in combined hyperlipidemia : preferential reduction of cholesteryl ester transfer from HDL to VLDL1 particles

Combined hyperlipidemia (CHL) is characterized by a concomitant elevation of plasma levels of triglyceride-rich, very low density lipoproteins (VLDLs) and cholesterol-rich, low density lipoproteins (LDLs). The predominance of small, dense LDLs contributes significantly to the premature development of coronary artery disease in patients with this atherogenic dyslipoproteinemia. In the present study, we evaluated the impact of atorvastatin, a newly developed inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase, on the cholesteryl ester transfer protein (CETP)-mediated remodeling of apolipoprotein (apo) B-containing lipoprotein subspecies, and more specifically, the particle subpopulations of VLDL and LDL in CHL. In parallel, we evaluated the atorvastatin-induced modulation of the quantitative and qualitative features of atherogenic apo B-containing and cardioprotective apo AI-containing lipoprotein subspecies. Atorvastatin therapy (10 mg/d for a 6-week period) in patients with a lipid phenotype typical of CHL (n=18) induced reductions of 31% (P<0.0001) and 36% (P<0.0001) in plasma total cholesterol and LDL cholesterol, respectively. In addition, atorvastatin significantly reduced VLDL cholesterol, triglycerides, and apo B levels by 43% (P<0.0001), 27% (P=0.0006), and 31% (P<0.0001), respectively. The plasma concentrations of triglyceride-rich lipoproteins (VLDL1, Sf 60 to 400; VLDL2, Sf 20 to 60; and intermediate density lipoproteins, Sf 12 to 20) and of LDL, as determined by chemical analysis, were markedly diminished after drug therapy (-30% and -28%, respectively; P<0.0007). Atorvastatin significantly reduced circulating levels of all major LDL subspecies, ie, light (-28%, P<0.0008), intermediate (-27%, P<0.0008), and dense (-32%, P<0.0008) LDL; moreover, in terms of absolute lipoprotein mass, the reduction in dense LDL levels (mean -62 mg/dL) was preponderant. In addition, the reduction in plasma dense LDL concentration after therapy was significantly correlated with a reduction in plasma VLDL1 levels (r=0.429, P=0.0218). Atorvastatin induced a significant reduction (-7%, P=0.0039) in total CETP-dependent CET activity, which accurately reflects a reduction in plasma CETP mass concentration. Total CETP-mediated CET from high density lipoproteins to apo B-containing lipoproteins was significantly reduced (-26%, P<0.0001) with drug therapy. Furthermore, CETP activity was significantly correlated with the atorvastatin-induced reduction in plasma VLDL1 levels (r=0.456, P=0. 0138). Indeed, atorvastatin significantly and preferentially decreased CET from HDL to the VLDL1 subfraction (-37%, P=0.0064), thereby reducing both the levels (-37%, P=0.0001) and the CE content (-20%, P<0.005) of VLDL1. We interpret our data to indicate that 2 independent but complementary mechanisms may be operative in the atorvastatin-induced reduction of atherogenic LDL levels in CHL: first, a significant degree of normalization of both the circulating levels and the quality of their key precursors, ie, VLDL1, and second, enhanced catabolism of the major LDL particle subclasses (ie, light, intermediate, and dense LDL) due to upregulation of hepatic LDL receptors.     

Dietary and genetic probes of atherogenic dyslipidemia

A goal of dietary management of cardiovascular disease risk in patients with obesity and metabolic syndrome is improvement in the atherogenic dyslipidemia comprising elevated triglyceride, reduced high-density lipoprotein (HDL) cholesterol, and increased numbers of small, dense low-density lipoprotein (LDL) particles. Individuals with a genetically influenced trait characterized by a high proportion of small, dense LDL (phenotype B) respond to a low-fat, high-carbohydrate diet with greater reduction of LDL cholesterol, apoprotein B, and mid-sized LDL2 particles than unaffected subjects (phenotype A). In contrast, in phenotype A subjects there is a reciprocal shift from large LDL1 to small LDL3 such that a high proportion convert to phenotype B. There is evidence for heritable effects on these diet-induced subclass changes and for the involvement of specific genes. For example, a haplotype of the APOA5 gene associated with increased plasma triglyceride and small, dense LDL predicts greater diet-induced reduction of LDL2, a haplotype-specific effect that is strongly correlated with both increased VLDL precursors and LDL4 products. Understanding of such diet-genotype interactions may help to elucidate mechanisms that are responsible for phenotype B and for its differential dietary responsiveness. This information may also ultimately help in identifying those individuals who are most likely to achieve cardiovascular risk benefit from specific dietary interventions.     

Lipids and lipoprotein subfractions in women with PCOS: relationship to metabolic and endocrine parameters

OBJECTIVE: Women with polycystic ovary syndrome (PCOS) exhibit an abnormal lipoprotein profile, characterized by raised concentrations of plasma triglyceride, marginally elevated low density lipoprotein (LDL)-cholesterol, and reduced high density lipoprotein (HDL)-cholesterol. However, a normal LDL-cholesterol level may be misleading since LDL exists as subpopulations of particles differing in size and atherogenic potential. Smaller LDL particles are more atherogenic and high concentrations often occur in association with elevated circulating triglyceride concentrations (but frequently normal total LDL-cholesterol), increased hepatic lipase activity (HL) and insulin resistance. Information on LDL subclasses and HL activity in women with PCOS is sparse. The aim of this study was to determine the concentrations of small, dense LDL (LDL-III) in women with PCOS relative to body mass index (BMI)-matched controls. We also examined the association of lipoprotein subfraction concentrations with endogenous sex hormone concentrations, since existing literature suggested that androgens up-regulate and oestrogens down-regulate HL activity, a key determinant of LDL subfraction distribution. DESIGN: Cross sectional study. PATIENTS: Fifty-two women with oligomenorrhoea and polycystic ovaries determined by ultrasound and BMI matched women with normal menstrual rhythm (NMR) and normal ovarian appearances (n = 14) were recruited from gynaecology clinics. Anthropometric data and fasting blood samples were obtained for metabolic, hormonal and LDL subfraction estimation and a heparin provocation test was used to estimate HL activity. RESULTS: Subjects with PCOS demonstrated higher waist:hip ratio (WHR), testosterone, triglyceride, VLDL-cholesterol concentrations, and HL activity (P < 0.05), whereas SHBG concentrations were significantly lower than controls. PCOS women had higher concentrations (38.0 vs. 25.0 mg/l; P = 0.026) and proportions (12.8 vs. 8.2%; P = 0.006) of small, dense LDL (LDL III), relative to controls. Within the PCOS group, plasma triglyceride and HL activity were the strongest univariate predictors of LDL III mass. They remained as independent predictors in multivariate analysis, and together accounted for 37% of its variability (P = 0.0002). Independent predictors of plasma triglyceride and HL in turn, were measures of fat distribution (waist circumference or WHR) and fasting insulin concentration. Serum testosterone concentration was not associated either in univariate or multivariate analysis with any of the measured lipid, lipoprotein or subfraction parameters, nor with HL activity in the women with PCOS. CONCLUSION: We conclude that women with polycystic ovary syndrome have increased hepatic lipase activity and mass and percentage of small, dense low density lipoprotein relative to body mass index-matched controls with normal menstrual rhythm and normal ovaries. Further, these metabolic perturbances appear related more closely to adiposity/insulin metabolism than to circulating androgen levels.     

Atherogenic lipoprotein phenotype. A proposed genetic marker for coronary heart disease risk

In a community-based study of 301 subjects from 61 nuclear families, two distinct phenotypes (denoted A and B) were identified by nondenaturing gradient gel electrophoretic analysis of low density lipoprotein (LDL) subclasses. Phenotype A was characterized by predominance of large, buoyant LDL particles, and phenotype B consisted of a major peak of small, dense LDL particles. Previous analysis of the family data by complex segregation analysis demonstrated that these phenotypes appear to be inherited as a single-gene trait. In the present study, the phenotypes were found to be closely associated with variations in plasma levels of other lipid, lipoprotein, and apolipoprotein measurements. Specifically, phenotype B was associated with increases in plasma levels of triglyceride and apolipoprotein B, with mass of very low and intermediate density lipoproteins, and with decreases in high density lipoprotein (HDL) cholesterol, HDL2 mass, and plasma levels of apolipoprotein A-I. Thus, the proposed genetic locus responsible for LDL subclass phenotypes also results in an atherogenic lipoprotein phenotype.     

Mechanisms of disease: lessons from ethnicity in the role of triglyceride metabolism in ischemic heart disease

Mean risk factor levels in various ethnic groups illustrate the potential importance of triglyceride metabolism in the risk for ischemic heart disease (IHD). Serum triglyceride concentrations are a surrogate for a range of potentially atherogenic disturbances in lipoprotein species, including increased concentrations of remnants of VLDL and chylomicron metabolism, increased small, dense LDL concentrations and reduced HDL concentrations. Differences between at-risk groups in lipoprotein profiles reflect alterations in the metabolism of triglycerides that might be greater than differences observed when only circulating triglyceride concentrations are measured. This atherogenic lipoprotein profile is typically found in association with increased visceral fat, insulin resistance and type 2 diabetes and might be a characteristic of Asian Indian ethnicity. By contrast, despite being relatively insulin resistant, Afro-Caribbean men in the UK have a low risk of IHD and lack the adverse lipoprotein profile. This could result from secretion of relatively large proportions of their VLDL as small, triglyceride-poor particles, levels of which are not augmented in response to loss of insulin action. These considerations re-endorse the potential importance of triglyceride metabolism in IHD and present opportunities for identifying useful areas in which drug targets for reducing IHD risk can be sought.     

Influence of mild to moderately elevated triglycerides on low density lipoprotein subfraction concentration and composition in healthy men with low high density lipoprotein cholesterol levels

Epidemiologic studies have shown that a dyslipoproteinemia with low concentrations of high density lipoprotein (HDL) cholesterol and elevated serum triglycerides (TG) is associated with a particularly high incidence of coronary artery disease. This lipid profile is associated with increased concentrations of small, dense low density lipoprotein (LDL) particles. To evaluate the role of mild to moderately elevated TG on the LDL subfraction profile in patients with low HDL cholesterol, concentration and composition of six LDL subfractions was determined by density gradient ultracentrifugation in 41 healthy men (31+/-9 years, body mass index (BMI) 25.1+/-3.9 kg/m2) with equally low HDL cholesterol levels < 0.91 mmol/l but different TG levels: TG < 1.13 mmol/l, n = 16; TG = 1.13-2.26 mmol/l, n = 13: TG = 2.26-3.39 mmol/l, n = 12. Those men with moderately elevated TG levels between 2.26 and 3.39 mmol/l had significantly higher concentrations of very low density lipoprotein (VLDL), intermediate low density lipoprotein (IDL), and small, dense LDL apoB and cholesterol than men with TG < 1.13 mmol/l. With increasing serum TG, the TG content per particle also increased in VLDL, IDL as well as total LDL particles while the cholesterol and phospholipid (PL) content decreased in VLDL and IDL, but not in LDL particles. LDL subfraction analysis revealed that only large, more buoyant LDL particles (d < 1.044 g/ml) but not the smaller, more dense LDL, were enriched in TG. Small, dense LDL particles were depleted of free cholesterol (FC) and PL. This study has shown that in men with low HDL cholesterol levels mild to moderately elevated serum TG strongly suggest the presence of other metabolic cardiovascular risk factors and in particular of a more atherogenic LDL subfraction profile of increased concentration of small, dense LDL particles that are depleted in surface lipids.     

Effect of niacin and atorvastatin on lipoprotein subclasses in patients with atherogenic dyslipidemia

This study was conducted to determine the efficacy of atorvastatin and niacin on lipoprotein subfractions in patients with atherogenic dyslipidemia. This was a multicenter, randomized, open-label, parallel-design study of patients with total cholesterol >200 mg/dl, triglycerides between 200 and 800 mg/dl, and apolipoprotein B >110 mg/dl. Patients were randomly assigned to atorvastatin 10 mg or immediate release niacin 3,000 mg daily for 12 weeks following a low-fat diet stabilization period. Lipoprotein subclasses were measured by nuclear magnetic resonance spectroscopy. Atorvastatin and niacin both significantly reduced the concentrations of very low-density lipoprotein (VLDL) particles (-31% and -29%, respectively) and small low-density lipoprotein (LDL) particles (-44% and -35%, respectively). Niacin increased the concentration of large LDL (+75%). Atrovastatin reduced the number of LDL particles more than niacin (31% vs 14%). In patients with atherogenic dyslipidemia, both drugs had important effects on lipoprotein subfractions, which contributed to a reduction in coronary heart disease risk. The drugs equally reduced VLDL subclass levels. Niacin shifted the LDL subclass distribution toward the larger particles, more effectively converted patients from LDL phenotype B to phenotype A, and increased levels of the larger and perhaps more cardioprotective high-density lipoprotein particles. In contrast, atorvastatin preferentially lowered the concentration of small LDL particles without increasing levels of large LDL, and more effectively, reduced LDL particle numbers. Atorvastatin had a preferred LDL effect, whereas niacin had a preferred high-density lipoprotein effect.     

Relationships of low density lipoprotein subfractions to angiographically defined coronary artery disease in young survivors of myocardial infarction.

Low density lipoprotein (LDL) from 36 young post-infarction patients was separated by isopycnic density gradient ultracentrifugation to determine the relationships of plasma levels and chemical composition of different LDL subfractions to the global severity and rate of progression of coronary atherosclerosis assessed by angiography. There were marked elevations of the cholesterol and triglyceride concentrations in the very low density lipoprotein (VLDL) fraction, whereas the high density lipoprotein (HDL) cholesterol level was reduced in the patients compared with 70 healthy population-based controls. Plasma total LDL cholesterol and triglyceride concentrations were similar. The distribution of apolipoprotein B along the LDL density range, viz. the LDL particle distribution, was displaced towards the dense LDL region among the patients compared with 14 healthy normolipidaemic controls. A preponderance of dense LDL particles was associated with elevated plasma VLDL triglyceride concentration. The patients had significantly higher plasma concentrations of lipid and protein in dense LDL (d greater than 1.040 kg/l), while no group differences were found in the light LDL (d less than 1.040 kg/l). However, there were no percentage compositional differences in the light or dense LDL between patients and controls. Among all constituents of lipoprotein fractions and subfractions determined, only the plasma level of triglycerides in both light and dense LDL correlated significantly with the angiographic estimates of global severity and rate of progression of coronary atherosclerosis, respectively. On a percentage composition basis, both light and dense LDL tended to be richer in triglycerides in the subjects with a more severe coronary artery disease. Neither VLDL or HDL, nor LDL cholesterol were associated with the angiographic scores, the plasma LDL triglyceride concentration or the triglyceride enrichment of LDL. Although there is ample experimental evidence that triglyceride-enriched LDL predisposes to atherosclerosis, the LDL associations with coronary lesion severity and progression observed in the present study might not reflect a causal mechanism, but merely mirror the atherogenicity of disturbances affecting the metabolism of triglyceride-rich lipoproteins. Prospective studies of larger groups of unselected patients are needed to corroborate these findings.     

Current Topics on Low‐Density Lipoprotein Apheresis

Abstract: The prognosis of patients suffering from severe hyperlipidemia, sometimes combined with elevated lipoprotein (a) (Lp[a]) levels, and coronary heart disease (CHD) refractory to diet and lipid‐lowering drugs is poor. For such patients, regular treatment with low‐density lipoprotein (LDL) apheresis is the therapeutic option. Today, there are four different LDL‐apheresis systems available: immunoadsorption, heparin‐induced extracorporeal LDL/fibrinogen precipitation, dextran sulfate LDL‐adsorption, and LDL‐hemoperfusion. Despite substantial progress in diagnostics, drug therapy, and cardiosurgical procedures, atherosclerosis with myocardial infarction, stroke, and peripheral cellular disease still maintains its position at the top of morbidity and mortality statistics in industrialized nations. Established risk factors widely accepted are smoking, arterial hypertension, diabetes mellitus, and central obesity. Furthermore, there is a strong correlation between hyperlipidemia and atherosclerosis. Besides the elimination of other risk factors, in severe hyperlipidemia (HLP) therapeutic strategies should focus on a drastic reduction of serum lipoproteins. Despite maximum conventional therapy with a combination of different kinds of lipid‐lowering drugs, however, sometimes the goal of therapy cannot be reached. Mostly, the prognosis of patients suffering from severe HLP, sometimes combined with elevated Lp(a) levels and CHD refractory to diet and lipid‐lowering drugs is poor. Hence, in such patients, treatment with LDL‐apheresis can be useful. Regarding the different LDL‐apheresis systems used, there were no significant differences with respect to the clinical outcome or concerning total cholesterol, LDL, high‐density lipoprotein, or triglyceride concentrations. With respect to elevated Lp(a) levels, however, the immunoadsorption method seems to be the most effective. The published data clearly demonstrate that treatment with LDL‐apheresis in patients suffering from severe hyperlipidemia refractory to maximum conservative therapy is effective and safe in long‐term application.     

Influence of atorvastatin and simvastatin on apolipoprotein B metabolism in moderate combined hyperlipidemic subjects with low VLDL and LDL fractional clearance rates

Subjects with moderate combined hyperlipidemia (n=11) were assessed in an investigation of the effects of atorvastatin and simvastatin (both 40 mg per day) on apolipoprotein B (apoB) metabolism. The objective of the study was to examine the mechanism by which statins lower plasma triglyceride levels. Patients were studied on three occasions, in the basal state, after 8 weeks on atorvastatin or simvastatin and then again on the alternate treatment. Atorvastatin produced significantly greater reductions than simvastatin in low density lipoprotein (LDL) cholesterol (49.7 vs. 44.1% decrease on simvastatin) and plasma triglyceride (46.4 vs. 39.4% decrease on simvastatin). ApoB metabolism was followed using a tracer of deuterated leucine. Both drugs stimulated direct catabolism of large very low density lipoprotein (VLDL(1)) apoB (4.52+/-3.06 pools per day on atorvastatin; 5.48+/-4.76 pools per day on simvastatin versus 2.26+/-1.65 pools per day at baseline (both P<0.05)) and this was the basis of the 50% reduction in plasma VLDL(1) concentration; apoB production in this fraction was not significantly altered. On atorvastatin and simvastatin the fractional transfer rates (FTR) of VLDL(1) to VLDL(2) and of VLDL(2) to intermediate density lipoprotein (IDL) were increased significantly, in the latter instance nearly twofold. IDL apoB direct catabolism rose from 0.54+/-0.30 pools per day at baseline to 1.17+/-0.87 pools per day on atorvastatin and to 0.95+/-0.43 pools per day on simvastatin (both P<0.05). Similarly the fractional transfer rate for IDL to LDL conversion was enhanced 58-84% by statin treatment (P<0.01) LDL apoB fractional catabolic rate (FCR) which was low at baseline in these subjects (0.22+/-0.04 pools per day) increased to 0.44+/-0.11 pools per day on atorvastatin and 0.38+/-0.11 pools per day on simvastatin (both P<0.01). ApoB-containing lipoproteins were more triglyceride-rich and contained less free cholesterol and cholesteryl ester on statin therapy. Further, patients on both treatments showed marked decreases in all LDL subfractions. In particular the concentration of small dense LDL (LDL-III) fell 64% on atorvastatin and 45% on simvastatin. We conclude that in patients with moderate combined hyperlipidemia who initially have a low FCR for VLDL and LDL apoB, the principal action of atorvastatin and simvastatin is to stimulate receptor-mediated catabolism across the spectrum of apoB-containing lipoproteins. This leads to a substantial, and approximately equivalent, percentage reduction in plasma triglyceride and LDL cholesterol.     

Effects of rosiglitazone alone and in combination with atorvastatin on the metabolic abnormalities in type 2 diabetes mellitus

This study evaluated the effects of rosiglitazone therapy on lipids and the efficacy and safety of rosiglitazone in combination with atorvastatin in patients with type 2 diabetes mellitus. Three-hundred thirty-two patients entered an 8-week, open-label, run-in treatment phase with rosiglitazone 8 mg/day, and 243 were randomized to a 16-week, double-blinded period of continued rosiglitazone plus placebo, atorvastatin 10 mg/day, or atorvastatin 20 mg/day. With rosiglitazone alone, a modest increase in low-density lipoprotein (LDL) cholesterol (9%), a shift in LDL phenotype from dense to large buoyant subfractions (52% of patients), and an increase in total high-density lipoprotein (HDL) cholesterol levels (6%), predominantly in HDL(2) levels (13%), occurred from week 0 to week 8. When atorvastatin was added, there was a further increase in HDL(3) (5%) and expected significant reductions (p <0.0001) in LDL cholesterol (-39%), apolipoprotein B (-35%), and triglyceride levels (-27%). Glycemic control achieved with rosiglitazone alone was not adversely affected by add-on atorvastatin. The combination was well tolerated compared with placebo. To conclude, in addition to the beneficial effects of rosiglitazone on glycemic control, rosiglitazone and atorvastatin in combination achieved 2 goals: the reduction of LDL cholesterol to <100 mg/dl and the removal of small dense LDL in patients with type 2 diabetes mellitus.     

冠心病患者血浆小而密低密度脂蛋白的分布特征

目的观察冠心病患者血浆低密度脂蛋白(lowdensitylipoprotein,LDL)亚组分的分布特征。方法采用密度梯度超速离心法分离24例冠心病患者和13例对照组血浆中脂蛋白的各亚组分:大而轻LDL(LDL1),中间LDL(LDL2),小而密LDL(LDL3,)的含量。结果①冠心病组与对照组在年龄、性别、身高、体重、总胆固醇、甘油三酯、高密度脂蛋白胆固醇(highdensitylipoproteincholesterol,HDL-C)、载脂蛋白A(apolipoproteinA,ApoA)和载脂蛋白B(apolipoproteinB,ApoB)和LDL等指标差异均无统计学意义(P>0.05);②冠心病组的亚组分LDL1的含量少,LDL3的含量多;对照组则相反,亚组分LDL1的含量多,LDL3的含量小;而且两组差异有统计学意义。而介于两者之间的亚组分LDL2的含量两组几乎一样。结论LDL3与冠心病的发生、发展有关;LDL3测定仍可作为预测冠心病危险性的指标之一,也是观察疗效的指标之一。     

Effects of increasing doses of atorvastatin on the atherogenic lipid subclasses commonly associated with hypertriglyceridemia

The increased cardiovascular risk associated with hypertriglyceridemia is thought to be due in part to high levels of triglyceride (TG)-rich lipoproteins and small dense low-density lipoprotein (LDL). In this post hoc analysis, effects of increasing doses of atorvastatin (10, 20, 40, and 80 mg) on atherogenic lipid subclasses commonly associated with hypertriglyceridemia were evaluated in 191 men and women who were candidates for lipid-lowering therapy and had baseline TG levels >200 mg/dl (2.3 mmol/L). After 8 weeks of treatment, in addition to significantly decreasing LDL cholesterol and TG levels, atorvastatin significantly increased LDL peak particle diameter (p <0.01) and significantly decreased the concentration of small LDL subclasses IIIa and IIIb (p <0.0001) from baseline at all doses. These effects were more pronounced with higher compared with lower doses of atorvastatin. Each dose of atorvastatin also significantly lowered levels of very LDL, intermediate-density lipoprotein (p <0.0001), and small very LDL subclass 3 (p <0.0001). Greater decreases were achieved by those patients receiving higher doses of atorvastatin (20, 40, and 80 mg). The increase in LDL size correlated with the decrease in TG levels, but not with the decrease in LDL cholesterol levels. However, the decrease in small dense LDL cholesterol concentrations correlated significantly with TG and LDL cholesterol decreases. In conclusion, atorvastatin significantly lowered levels of TG-rich remnant lipoproteins and favorably changed LDL particle size in patients with hypertriglyceridemia. These effects may explain the benefits of statin therapy in high-risk patients with hypertriglyceridemia even when levels of LDL cholesterol are at goal.