Inter-relationships between small, dense low-density lipoprotein (LDL), plasma triacylglycerol and LDL apoprotein B in an atherogenic lipoprotein phenotype in free-living subjects.

A predominance of small, dense low-density lipoprotein (LDL) is a major component of an atherogenic lipoprotein phenotype, and a common, but modifiable, source of increased risk for coronary heart disease in the free-living population. While much of the atherogenicity of small, dense LDL is known to arise from its structural properties, the extent to which an increase in the number of small, dense LDL particles (hyper-apoprotein B) contributes to this risk of coronary heart disease is currently unknown. This study reports a method for the recruitment of free-living individuals with an atherogenic lipoprotein phenotype for a fish-oil intervention trial, and critically evaluates the relationship between LDL particle number and the predominance of small, dense LDL. In this group, volunteers were selected through local general practices on the basis of a moderately raised plasma triacylglycerol (triglyceride) level (>1.5 mmol/l) and a low concentration of high-density-lipoprotein cholesterol (<1.1 mmol/l). The screening of LDL subclasses revealed a predominance of small, dense LDL (LDL subclass pattern B) in 62% of the cohort. As expected, subjects with LDL subclass pattern B were characterized by higher plasma triacylglycerol and lower high-density lipoprotein cholesterol (<1.1 mmol/l) levels and, less predictably, by lower LDL cholesterol and apoprotein B levels (P<0.05; LDL subclass A compared with subclass B). While hyper-apoprotein B was detected in only five subjects, the relative percentage of small, dense LDL-III in subjects with subclass B showed an inverse relationship with LDL apoprotein B (r=-0.57; P<0.001), identifying a subset of individuals with plasma triacylglycerol above 2.5 mmol/l and a low concentration of LDL almost exclusively in a small and dense form. These findings indicate that a predominance of small, dense LDL and hyper-apoprotein B do not always co-exist in free-living groups. Moreover, if coronary risk increases with increasing LDL particle number, these results imply that the risk arising from a predominance of small, dense LDL may actually be reduced in certain cases when plasma triacylglycerol exceeds 2.5 mmol/l.     

基于芯片电泳技术的低密度脂蛋白检测及应用研究

目的建立芯片电泳分离血清低密度脂蛋白并探讨其临床应用价值。方法采用自制的微流控石英芯片,以pH9.8、50 mmol/L的Tricine作为芯片电泳缓冲体系,选择十二烷基硫酸钠(SDS)作为添加剂,分离血清脂蛋白。结果低密度的2个亚型,即大而轻低密度脂蛋白(lLDL)、小而密低密度脂蛋白(sdLDL)在3 min内得到有效分离。与健康体检者相比,冠心病患者体内含有更高浓度的sdLDL。结论芯片电泳能快速、简便、有效地分离出冠心病患者血清中低密度脂蛋白亚型,表明此法有望成为检测sdLDL的常规分析方法。     

化学沉淀法测定小而密低密度脂蛋白方法的建立

目的利用化学沉淀原理建立小而密低密度脂蛋白(sdLDL)快速、简便的检测方法。方法通过比较不同种类及不同浓度沉淀剂对血清样本中脂蛋白的分离效果,确定最终沉淀剂,并对化学沉淀法测定血清sdLDL-C的精密度、线性范围和回收率进行分析。结果最终选择140 U/mL肝素-90 mmol/L Mg2+作为沉淀剂测定血清sdLDL胆固醇(sdLDL-C)含量。化学沉淀法测定sdLDL-C在0.14~1.44 mmol/L范围内线性关系良好,回归方程为Y=1.025X-0.197,r=0.988;对高、低2组不同sdLDL-C浓度的样本批内变异系数(CV)分别为2.83%、3.19%,批间CV分别为5.49%、6.13%;回收率为83.81%。结论 sdLDL化学沉淀法具有样本用量少、操作简便、成本低廉等优点,更适合常规实验室检测血清sdLDL-C含量。     

微流控芯片电泳测定血清小而密低密度脂蛋白及临床应用价值

目的建立微流控芯片电泳分离血清小而密低密度脂蛋白(sdLDL)的方法并探讨其临床应用价值。方法利用自制的微流控芯片,选择Tricine缓冲液为电泳缓冲液,SDS作为添加剂,电泳分离经硝基苯并噁二唑-C6-酰基鞘胺醇(NBD C6-ceram-ide)预染的脂蛋白,激光诱导荧光技术检测。结果大而轻低密度脂蛋白(lLDL)、sdLDL、极低密度脂蛋白(VLDL)和高密度脂蛋白(HDL)在3 min内得到有效分离。冠心病(CHD)组,sdLDL检出率显著高于正常对照组(P<0.01)。CHD患者血清经连续3次分析,sdLDL出峰时间和峰面积相对标准差分别为2.18%和2.94%。sdLDL阳性组TG水平增高,HDL-C水平降低,均与阴性组存在显著差异(P<0.01和P<0.05)。CHD患者sdLDL与三酰甘油(TG)、载脂蛋白B(apoB)呈正相关(r=0.82和0.79,P<0.0001)。结论微流控芯片电泳可望成为sdLDL的常规分析手段,用于CHD危险性的评估。     

小而密低密度脂蛋白胆固醇与冠状动脉粥样硬化特征的相关性分析

目的结合影像学评价小而密低密度脂蛋白胆固醇(sdLDL-C)与冠状动脉(以下简称"冠脉")粥样硬化病变严重程度的关系。方法连续选取2015年7月至2016年3月阜外医院436例门诊初诊怀疑冠脉粥样硬化性心脏病(CAD)并行冠脉计算机断层摄影术检查(CT)的患者,从斑块性质、病变支数及狭窄程度3个方面分析sdLDL-C与冠脉粥样硬化严重程度的相关性。结果 sdLDL-C与载脂蛋白B(apoB)、三酰甘油(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、血糖(Glu)呈正相关(r依次为0.644、0.631、0.558、0.434、0.145,P均0.01),与高密度脂蛋白胆固醇(HDL-C)呈负相关(r=-0.241,P0.01);sdLDL-C、apoB可作为严重CAD(三支病变及重度狭窄75%)发生的危险因素,且独立于传统风险因素(年龄、性别、高血压史、糖尿病史、吸烟史、饮酒史)及他汀类降脂药的应用;对于三支病变,LDL-C、sdLDL-C、apoB预测价值依次增强(OR依次为1.936、2.673、31.707);对于重度狭窄,LDL-C非独立危险因素,sdLDL-C、apoB有预测价值(OR分别为2.000、9.457)。结论 sdLDL-C可作为独立于传统风险因素的严重CAD预测指标,预测价值优于LDL-C,有可能作为进一步的风险控制指标。     

Small, dense low density lipoprotein (LDL) and the insulin resistance syndrome (IRS)

The preponderance of small, dense LDL particles has been termed a conditional cardiovascular risk factor, indicating that data derived from experimental, clinical and intervention studies suggest a strong relation of LDL size and cardiovascular (atherosclerotic) disease (77). However, the lack of randomized, controlled trials showing a beneficial effect of increasing LDL size on cardiovascular disease independent of other known risk factors (including hypertriglyceridemia) precludes the inclusion of small, dense LDL into the category of "causal" risk factors. Accordingly, as of today, LDL particle size can not (yet) be considered a primary target of risk factor intervention, and neither can its routine assessment for clinical purposes be recommended. Numerous studies have unanimously shown that components of the IRS, including insulin resistance itself, constitute major environmental determinants of LDL size. Therefore, therapies aiming at improving insulin resistance have the potential to modify small, dense LDL towards larger, more buoyant particles. Randomized controlled trials investigating the effect of these therapies not only on LDL size but also on clinical (cardiovascular) endpoints will be of particular interest.     

南通地区健康体检人群小而密低密度脂蛋白水平调查

目的 初步调查南通地区健康人群小而密LDL(胆固醇和蛋白质)的分布情况.方法 体格检查和实验窜检查均无异常的健康人群254名(男137名,女117名),按年龄分成20～29岁(65名)、30～39岁(65名)、40～49岁(46名)、50～69岁(35名)、和370岁(43名)5组.检测采用全自动生化分析仪和芯片电泳技术.结果 小而密LDL胆固醇和蛋白质水平均值为(0.39±0.14)mmol/L和(241±158)mg/L,小而密LDL胆固醇与总胆固醇、三酰甘油、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇相关性较好(r=0.67、0.35、-0.42和0.46,P均<0.01),小而密LDL蛋白质与这些血脂指标相关性较好(r=O.54、0.24、-0.32和0.52,P均<0.01).小而密LDL蛋白质和胆固醇水平随年龄增高呈上升趋势,而70岁以上人群呈下降趋势;男性小而密低密度脂蛋白水平高于女性[(0.40±0.11)mmol/L vs.(O.37±0.17)mmol/L,P<0.01;(253±59)mg/L vs.(237±95)mg/L,P<0.05],P相似文献   

Comparative reactivity of remnant-like lipoprotein particles (RLP) and low-density lipoprotein (LDL) to LDL receptor and VLDL receptor: effect of a high-dose statin on VLDL receptor expression

BackgroundComparison of the reactivity of remnant-like lipoprotein particles (RLP) and LDL particles to LDL receptor and VLDL receptor has not been investigated.MethodsLDL receptor- or VLDL receptor-transfected ldlA-7, HepG2 and L6 cells were used. Human LDL and rabbit β-VLDL were isolated by ultracentrifugation. Human RLP was isolated using an immunoaffinity mixed gel. The effect of statin on lipoprotein receptors was examined.ResultsBoth LDL receptor and VLDL receptor recognized RLP. In LDL receptor transfectants, RLP, β-VLDL and LDL all bound to LDL receptor. Cold RLP competed efficiently with DiI-β-VLDL; however, cold LDL competed weakly. In VLDL receptor transfectants, RLP and β-VLDL bound to VLDL receptor, but not LDL. RLP bound to VLDL receptor with higher affinity than β-VLDL because of higher apolipoprotein E in RLP. LDL receptor expression was induced in HepG2 by the low concentration of statin while VLDL receptor expression was induced in L6 myoblasts at higher concentration.ConclusionsRLP are bound to hepatic LDL receptor more efficiently than LDL, which may explain the mechanism by which statins prevent cardiovascular risk by primarily reducing plasma RLP rather than by reducing LDL. Additionally, a high-dose of statins also may reduce plasma RLP through muscular VLDL receptor.     

Application of a modified precipitation method for the measurement of small dense LDL-cholesterol (sd-LDL-C) in a population in southern Brazil

Abstract Background: In the study reported herein, we used the precipitation method employing heparin-Mg2+, with slight modifications to avoid lipemia interference, to measure small dense-low density lipoprotein-cholesterol (sd-LDL-C) in Brazilian subjects with a high risk of developing cardiovascular diseases. Methods: Lipemic samples were diluted with various solvents prior to precipitation with heparin-Mg2+. Validation assays were performed with ultracentrifugation (n=100) and the reproducibility of sd-LDL-C measured in diluted serum (n=50). The applicability of this modification was evaluated by measuring sd-LDL-C in 434 southern Brazilian normolipidemic, dyslipidemic and type 2 diabetes mellitus (T2DM) individuals. Results: Lipemic serum diluted with 100 mmol/L phosphate buffer pH 8.5 was effective for the quantification of sd-LDL-C, which was correlated with non-diluted serum (r=0.961; p<0.0001) and with ultracentrifugation (r=0.705; p<0.0001). Ultracentrifugation sd-LDL-C was 0.08 mmol/L (CI 95%: -0.42-0.58 mmol/L) higher than the precipitation method (p>0.05). Subjects with dyslipidemias and T2DM had, respectively, 2.3 and 2.6-fold higher sd-LDL-C concentrations than normolipidemic individuals (p<0.05). The incidence of normolipidemic subjects with a high concentration of sd-LDL-C was only 2.2%. The sd-LDL-C was found to be enhanced by 8.3% every 10 years and young normolipidemic men had 24% higher sd-LDL-C than young women (p<0.05). Lipid-lowering therapy reduced sd-LDL-C by 26% (p<0.001). Conclusions: In this paper we described a simple and inexpensive approach to improving the measurement of sd-LDL-C in high-triglycerides serum. Furthermore, we showed that southern Brazil dyslipidemic and T2DM individuals have increased sd-LDL-C concentrations.     

Impact of postprandial lipaemia on low-density lipoprotein (LDL) size and oxidized LDL in patients with coronary artery disease

BACKGROUND: Remnant lipoprotein particles (RLPs) and oxidative stress are components of postprandial state. We investigated the concentrations of triglyceride-rich lipoproteins (TRLs), RLPs, low-density lipoprotein (LDL) size, and oxidized LDL (oxLDL) during alimentary lipaemia, and evaluated whether changes among these variables could be associated with the severity and extent of coronary artery disease (CAD). MATERIALS AND METHODS: Eighty men and 27 women with clinically suspected CAD underwent quantitative coronary angiography (QCA). TRLs were isolated by density gradient ultracentrifugation before and 6 h after an oral fat load. RLPs were measured by an immunoseparation method, oxLDL by ELISA, and LDL size by gradient gel electrophoresis. RESULTS: Triglycerides, apolipoprotein (apo) B-48, and apoB-100 concentration in Swedberg flotation units (Sf) > 400 and in Sf 12-400 fractions were markedly increased at 6 h. Postprandial cholesterol content of RLPs (RLP-C) correlated with respective triglycerides in Sf > 400 (r = 0.737) and Sf 12-400 (r = 0.857), apoB-48 in Sf > 400 (r = 0.710) and Sf 12-400 (r = 0.664), apoB-100 in Sf > 400 (r = 0.812) and Sf 12-400 (r = 0.533). RLP-C correlated with oxLDL both in fasting and in fed state (r = 0.482 and r = 0.543, respectively) and inversely with LDL size (r = -0.459 and r = -0.442, respectively). (P < 0.001 for all). OxLDL was elevated postprandially (P < 0.001). In multivariate analysis, oxLDL was a determinant of severity and extent of CAD. CONCLUSION: Postprandial state is associated with oxidative stress. The magnitude of oxLDL increases during alimentary lipaemia and is associated with coronary atherosclerosis.     

Lack of correlation between the maximum low-density lipoprotein (LDL) receptor activity of blood lymphocytes and plasma LDL concentration in normal men

1. Measurements were made of the maximal low-density lipoprotein (LDL) receptor activities of blood lymphocytes from 81 healthy men with a wide range of plasma LDL cholesterol concentrations (1.45-7.55 mmol/l). 2. Receptor activity was quantified by measuring the degradation of 125I-labelled LDL (10 micrograms of protein/ml) to trichloroacetic acid-soluble material during a 6 h incubation, after derepression of the lymphocytes for 72 h in lipoprotein-deficient medium. 3. No significant correlation existed between LDL receptor activity in vitro and plasma LDL cholesterol concentration in vivo (r = -0.08).     

Prospective cross-over comparisons of three low-density lipoprotein (LDL)-apheresis methods in patients with familial hypercholesterolaemia

We prospectively compared effectiveness, selectivity and biocompatibility of three LDL-apheresis methods, immunoadsorption (IMAL), dextran sulphate adsorption (DSAL) and heparin-induced extracorporeal LDL precipitation (HELP). Seven patients with familial hypercholesterolaemia were treated twice with each method in random sequence. Reduction in atherogenic lipoproteins was without significant difference: LDL −60% to −75%, VLDL −20% to −30%, triglycerides −20% to −42%. High-density lipoprotein (HDL)-cholesterol was reduced by IMAL only (−27%, P <0.05); DSAL and HELP did not decrease HDL. Total plasma protein reduction was 13–15% with each method, indicating unselectivity. Albumin was significantly decreased by IMAL (−15%, P <0.05) but not by the other methods. DSAL and HELP reduced fibrinogen (−40%, −58%, P <0.0001) and other clotting factors. IMAL had almost no effect on coagulation. The white blood cell count did not change. C3 and C4 complement were decreased (−20% to −46%) by all methods. C5a complement did not increase in systemic blood, but was increased in the extracorporeal circulation of IMAL (+200%) and HELP (+150%). Plasma PMN elastase rose in all methods (+200%) indicating neutrophile degranulation. In conclusion, in this short-term study of a small patient population, effectiveness of the three LDL-apheresis methods was similar, but selectivity and biocompatibility were different. The therapeutic relevance of these differences for long-term treatment remains to be elucidated.     

The significance of autoantibodies against oxidatively modified low-density lipoprotein (LDL) in patients with psoriasis.

Psoriasis is associated with changes in plasma lipid and lipoproteins, which may play a role in the development of occlusive vascular disease. The oxidation of low-density lipoprotein (LDL) is considered a key event in the development and progression of atherosclerosis. Autoantibodies against oxidized LDL (auAb-oxLDL) may contribute to understanding the relationship between oxidative processes and development of atherosclerosis. Thirty-three patients with psoriasis and 30 matched control subjects were investigated. LDL oxidation was evaluated as the presence of autoantibodies against LDL oxidatively modified with Cu++, by an ELISA system in the patients and control sera. AuAb-ox LDL levels of the patients were found to be significantly increased compared with a control group. 42% of the patients and 3.3% of the control subjects had higher auAb-ox LDL levels than the cut-off point (352 mU/ml). The levels of auAb-ox LDL were found to be correlated with PASI score (r = 0.67, p < 0.01). Also, The antibody level was found to be correlated with polymorphonuclear elastase and alpha-1 antitrypsin levels (r = 0.58, p < 0.05; r = 0.51, p < 0.05, respectively). It was concluded that increased levels of auAb-oxLDL in the psoriatic patients may be a consequence of the interaction between imbalance of oxidant-antioxidant system and lipoproteins, and the measurement of auAb-oxLDL in the patients may mirror in vivo occurrence of oxidative processes.     

Comparison of low-density lipoprotein cholesterol concentrations measured by a direct homogeneous assay and by the Friedewald formula in a large community population

BackgroundWe compare the direct homogeneous low-density lipoprotein cholesterol (LDL-C) assay with the Friedewald formula (FF) for determination of LDL-C in a large community-dwelling population.MethodsA total of 21,194 apparently healthy subjects aged 40 to 79 years with triglyceride (TG) concentrations < 4.52 mmol/l were enrolled. LDL-C were directly measured by the enzymatic homogeneous assay (LDL-C (D)) and also estimated by the FF (LDL-C (F)). Paired t-test, Pearson's correlation coefficient and linear regression analysis were performed and the concordances of the National Cholesterol Education Program (NCEP) risk category were estimated.ResultsBoth in fasting (n = 3270) and nonfasting samples (n = 17,924), LDL-C (D) highly correlated with LDL-C (F): r = 0.971 and 0.955, respectively. Concordant results for NCEP categories were 84.8% for fasting samples and 80.1% for nonfasting samples. However, the bias between the 2 measurements increased in samples with TG concentrations > 1.69 mmol/l, especially in nonfasting samples.ConclusionsThe results showing less variability of the direct LDL-C assay than that of the FF in nonfasting samples suggest that epidemiological studies can use LDL-C measured by the direct assay both in fasting and nonfasting samples.     

血清小而密低密度脂蛋白胆固醇水平对冠心病患者心血管不良事件的预测价值

目的分析冠心病(CAD)患者血清小而密低密度脂蛋白胆固醇(sdLDL-C)的水平,并评估sdLDL-C对CAD患者主要心血管不良事件(MACE)发生风险的预测价值。方法检测93例急性冠状动脉综合征(ACS)、48例稳定性CAD(SCAD)患者和123例健康对照者的血清sdLDL-C水平。计算CAD患者的Gensini积分,随访CAD患者1年内MACE的发生情况。采用Spearman相关和多元线性回归分析CAD患者血清sdLDL-C水平与Gensini积分的关系。采用多元Logistic回归分析血清sdLDL-C评估CAD发生风险的预测价值。采用Cox回归分析血清sdLDL-C评估CAD患者MACE发生风险的预测价值。结果ACS组血清sdLDL-C水平高于对照组(P<0.001)和SCAD组(P=0.038)。CAD患者血清sdLDL-C水平与Gensini积分独立相关(β=0.315,P=0.017,校正R^2=0.083)。多因素Logisitic回归分析显示,血清高sdLDL-C水平与ACS发生风险密切相关(OR=7.895,95%CI:2.344~26.589,P=0.001),且对ACS和SCAD的区分具有统计学意义(OR=5.948,95%CI:1.158~30.558,P=0.033)。随访1年内,CAD患者的MACE发生率为22.70%;发生MACE的CAD患者血清sdLDL-C水平高于未发生MACE的CAD患者(P=0.001)。多因素Cox回归分析显示,血清高sdLDL-C水平与CAD患者MACE的发生风险密切相关(HR=5.326,95%CI:1.623~17.483,P=0.006)。结论ACS患者血清sdLDL-C水平升高;血清sdLDL-C可望作为评估CAD患者MACE发生风险的预测指标。