血清ApoB/ApoA1比值、TG/HDL-C比值、LDH及ALP水平与冠心病患者冠状动脉病变严重程度的关系及其预测价值分析

摘要 目的：探讨血清载脂蛋白B（ApoB）/载脂蛋白A1（ApoA1）比值、三酰甘油（TG）/高密度脂蛋白胆固醇（HDL-C）比值、乳酸脱氢酶（LDH）及碱性磷酸酶（ALP）水平与冠心病（CHD）患者冠状动脉病变严重程度的关系及其预测价值。方法：选取2019年1月-2021年12月因胸痛来我院检查并收治的185例患者,根据检查结果是否为CHD分为CHD组（120例）和对照组（65例）,根据Gensini评分将CHD组分为轻度狭窄亚组36例、中度狭窄亚组55例、重度狭窄亚组29例。入院后检测血清ApoB/ApoA1比值、TG/HDL-C比值、LDH及ALP水平。采用Spearman相关系数分析CHD患者血清ApoB/ApoA1比值、TG/HDL-C比值、LDH、ALP水平与Gensini评分的相关性,采用多因素Logistic回归分析CHD的影响因素;受试者工作特征（ROC）曲线分析血清ApoB/ApoA1比值、TG/HDL-C比值、LDH及ALP水平对CHD的预测价值。结果：与对照组比较,CHD组吸烟、饮酒、高血压、糖尿病比例和血清总胆固醇（TC）、TG、低密度脂蛋白胆固醇（LDL-C）、ApoB、ApoB/ApoA1比值、TG/HDL-C比值、LDH、ALP水平升高,HDL-C、ApoA1水平降低（P＜0.05）。轻度、中度、重度狭窄亚组血清ApoB/ApoA1比值、TG/HDL-C比值、LDH及ALP水平依次升高（P＜0.05）。CHD患者血清ApoB/ApoA1比值、TG/HDL-C比值、LDH、ALP水平与Gensini评分呈正相关（P均＜0.001）。多因素Logistic回归分析显示,高血压、血清ApoB/ApoA1比值、TG/HDL-C比值、LDH、ALP水平升高为CHD的独立危险因素（P＜0.05）。ROC曲线分析显示,血清ApoB/ApoA1比值、TG/HDL-C比值、LDH及ALP水平联合预测CHD的曲线下面积大于单独预测（P＜0.05）。结论：血清ApoB/ApoA1比值、TG/HDL-C比值、LDH、ALP水平与CHD患者冠状动脉病变严重程度有关,且联合预测CHD的价值较高。     

Molecular cloning,expression, and hormonal regulation of the chicken microsomal triglyceride transfer protein

During an egg-laying cycle, oviparous animals transfer massive amounts of triglycerides, the major lipid component of very low density lipoprotein (VLDL), from the liver to the developing oocytes. A major stimulus for this process is the rise in estrogen associated with the onset of an egg-laying cycle. In mammals, the microsomal triglyceride transfer protein (MTP) is required for VLDL assembly and secretion. To enable studies to determine if MTP plays a role in basal and estrogen-stimulated VLDL assembly and secretion in an oviparous vertebrate, we have cloned and sequenced the chicken MTP cDNA. This cDNA encodes a protein of 893 amino acids with an N-terminal signal sequence. The primary sequence of chicken MTP is, on average, 65% identical to that of mammalian homologs, and 23% identical to the Drosophila melanogaster protein. We have obtained a clone of chicken embryo fibroblast cells that stably express the avian MTP cDNA and show that these cells display MTP activity as measured by the transfer of a fluorescently labeled neutral lipid. As in mammals, chicken MTP is localized to the endoplasmic reticulum as revealed by indirect immunofluorescence and by the fact that its N-linked oligosaccharide moiety remains sensitive to endoglycosidase H. Endogenous, enzymatically active MTP is also expressed in an estrogen receptor-expressing chicken hepatoma cell line that secretes apolipoprotein B-containing lipoproteins. In this cell line and in vivo, the expression and activity of MTP are not influenced by estrogen. Therefore, up-regulation of MTP in the liver is not required for the increased VLDL assembly during egg production in the chicken. This indicates that MTP is not rate-limiting, even for the massive estrogen-induced secretion of VLDL accompanying an egg-laying cycle.     

Uncoupling associations of risk alleles with endophenotypes and phenotypes: insights from the ApoB locus and heart‐related traits

Traditionally, genomewide association studies (GWAS) have emphasized the benefits of large samples in the analyses of age‐related traits rather than their specific properties. We adopted a realistic concept of genetic susceptibility to inherently heterogeneous, age‐related traits driven by the elusive role of evolution in their properties. We analyzed in detail the associations of rs693 and rs562338 polymorphisms representing the Apolipoprotein B locus with endophenotypes (total cholesterol [TC] and high‐density lipoprotein cholesterol) and phenotypes (myocardial infarction [MI] and survival) in four large‐scale studies, which include 20 748 individuals with 2357 MI events. We showed that a strong, robust predisposition of rs693 and rs562338 to TC (β = 0.72, P = 7.7 × 10^?30 for rs693 and β = ?1.08, P = 9.8 × 10^?42 for rs562338) is not translated into a predisposition to MI and survival. The rs693_A allele influences risks of MI and mortality after MI additively with lipids. This allele shows antagonistic effects—protecting against MI risks (β = ?0.18, P = 1.1 × 10^?5) or increasing MI risks (β = 0.15, P = 2.8 × 10^?3) and mortality after MI, in different populations. Paradoxically, increased TC concentrations can be protective against MI for the rs693_A allele carriers. Our results uncouple the influences of the same alleles on endophenotypes and phenotypes despite potential causal relationships among the latter. Our strategy reveals virtually genomewide significance for the associations of rs693 with MI (P = 5.5 × 10^?8) that is contrasted with a weak estimate following the traditional, sample‐size‐centered GWAS strategy (P = 0.16) in the same sample. These results caution against the use of the traditional GWAS strategy for gaining profound insights into genetic predisposition to healthspan and lifespan.     

ApoB与UCP基因间上位效应对鸡腹脂性状影响的遗传学分析

已有研究表明, 上位效应在畜禽重要复杂经济性状的表型形成过程中发挥重要作用。文章选取对肉鸡7 周龄腹脂率有显著影响的载脂蛋白B(Apoliprotein B, ApoB)基因T123G位点与解耦连蛋白(Uncoupling protein, UCP)基因C1197A位点, 在东北农业大学肉鸡高、低腹脂双向选择品系8、9、10世代内检测这两个SNPs的多态性并利用Natural and Orthogonal InterActions (NOIA)模型分析二者之间的上位效应对7周龄腹脂率的影响。结果表明, 在高脂系内这两个位点之间存在着对7周龄腹脂率有显著影响的上位效应组分(P<0.05), 并且在连续多世代选育过程中仍能持续稳定存在; 同时, 在低脂系中二者之间各上位效应组分对腹脂率均无影响(P>0.05)。此结果意味着, 至少在高脂系内, 腹脂率的遗传受到这两个基因间上位效应的影响; 同时提示两系间脂肪性状QTL或重要候选基因功能位点之间不同的遗传互作模式可能是引起这两个品系腹脂性状巨大表型差异的重要影响因素之一。     

中国汉族apoB基因EcoRI、XbaI、MspI、Ins/Del及3＇端VNTR位点的多态性研究

目的：apo B基因多态性对群体遗传学、心血管疾病等研究领域有着重要的价值,本文分析了中国汉族人群中apoB基因EcoRI、XbaI、MspI、Ins/Del及3＇端VNTR等5个多态性位点的等位基因频率分布,为相关研究提供基础资料。方法：应用PCR-RFLP技术分析EcoRI、XbaI、MspI等3个位点的多态性分布,应用常规PCR方法分析Ins/Del及3＇端VNTR等2个位点的多态性分布。结果：1人群中EcoRI位点有E＋及E-两种等位基因,基因频率分别为87.1%和12.9%;XbaI位点有X＋及X-两种等位基因,基因频率分别为6.1%和93.9%;MspI位点有M＋及M-两种等位基因,基因频率分别为97.1%和2.3%;Ins/Del位点有Ins及Del两种等位基因,基因频率分别为70.7%和29.3%;3＇端VNTR位点有16种等位基因,其中以HVE34与HVE36最为常见,频率分别为33.4%与21%。2连锁不平衡分析表明,5个位点间除XbaI与Ins/Del间存在较弱的连锁不平衡（D＇=0.911,r2=0.175）,其余点位间无显著连锁不平衡。结论：数据比对表明,5个多态性位点的基因型和等位基因频率存在民族、种族差异,因此在apo B基因相关研究中应充分考虑遗传背景造成的影响。     

An Antibody against the C-Terminal Domain of PCSK9 Lowers LDL Cholesterol Levels In Vivo

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is associated with autosomal dominant hypercholesterolemia, a state of elevated levels of LDL (low-density lipoprotein) cholesterol. Autosomal dominant hypercholesterolemia can result in severe implications such as stroke and coronary heart disease. The inhibition of PCSK9 function by therapeutic antibodies that block interaction of PCSK9 with the epidermal growth factor-like repeat A domain of LDL receptor (LDLR) was shown to successfully lower LDL cholesterol levels in clinical studies. Here we present data on the identification, structural and biophysical characterization and in vitro and in vivo pharmacology of a PCSK9 antibody (mAb1). The X-ray structure shows that mAb1 binds the module 1 of the C-terminal domain (CTD) of PCSK9. It blocks access to an area bearing several naturally occurring gain-of-function and loss-of-function mutations. Although the antibody does not inhibit binding of PCSK9 to epidermal growth factor-like repeat A, it partially reverses PCSK9-induced reduction of the LDLR and LDL cholesterol uptake in a cellular assay. mAb1 is also effective in lowering serum levels of LDL cholesterol in cynomolgus monkeys in vivo. Complete loss of PCSK9 is associated with insufficient liver regeneration and increased risk of hepatitis C infections. Blocking of the CTD is sufficient to partially inhibit PCSK9 function. Antibodies binding the CTD of PCSK9 may thus be advantageous in patients that do not tolerate complete inhibition of PCSK9.     

Apolipoprotein E gene polymorphisms in Lebanese with hypercholesterolemia

Apolipoprotein E (ApoE) has an important role in the metabolism of lipids through its major isoforms (ε2, ε3, ε4). In particular, ApoE ε4, has been considered as a major genetic risk factor for cardiovascular diseases (CVD). The aim of our study is to investigate the frequency of ApoE gene polymorphisms (rs 429358C > T, rs 7412C > T) and their relationship to lipid parameters in a group of Lebanese hypercholesterolemic subjects (22 males and 24 females, aged 25–80 years). Lipid profile, apolipoproteins A-I and B were determined using fasting serum samples; and molecular analysis of ApoE polymorphisms using blood in EDTA tubes. The distribution of the four ApoE genotypes detected in this study was: ε3/ε3 (73.9%), ε3/ε4 (17.4%), ε2/ε3 (6.5%), and ε2/ε4 (2.2%) resulting in allelic frequencies for ε2, ε3 and ε4 of 4.3%, 85.9% and 9.8%, respectively. No association was determined among any of the lipid parameters, gender and ApoE genotypes. Lipid parameters were not statistically different among various ApoE genotypes (p > 0.05). ApoE ε2 frequency was found to be lower than that previously reported for healthy Lebanese (7.2%). CVD is one of the major leading causes of mortality in Lebanon with a reported prevalence of 12.2% in males and 7.7% in females, which incidentally agrees with our finding regarding ε4 allelic frequency of 13.6% in males and 6.3% in females. Consequently, larger prospective studies are recommended to highlight the correlation of ApoE polymorphisms to other biochemical and environmental factors involved in CVD.     

Hepatic ABCG5/G8 overexpression reduces apoB-lipoproteins and atherosclerosis when cholesterol absorption is inhibited

We previously reported that liver-specific overexpression of ABCG5/G8 in mice is not atheroprotective, suggesting that increased biliary cholesterol secretion must be coupled with decreased intestinal cholesterol absorption to increase net sterol loss from the body and reduce atherosclerosis. To evaluate this hypothesis, we fed low density lipoprotein receptor-knockout (LDLr-KO) control and ABCG5/G8-transgenic (ABCG5/G8-Tg)xLDLr-KO mice, which overexpress ABCG5/G8 only in liver, a Western diet containing ezetimibe to reduce intestinal cholesterol absorption. On this dietary regimen, liver-specific ABCG5/G8 overexpression increased hepatobiliary cholesterol concentration and secretion rates (1.5-fold and 1.9-fold, respectively), resulting in 1.6-fold increased fecal cholesterol excretion, decreased hepatic cholesterol, and increased (4.4-fold) de novo hepatic cholesterol synthesis versus LDLr-KO mice. Plasma lipids decreased (total cholesterol, 32%; cholesteryl ester, 32%; free cholesterol, 30%), mostly as a result of reduced non-high density lipoprotein-cholesterol and apolipoprotein B (apoB; 36% and 25%, respectively). ApoB-containing lipoproteins were smaller and lipid-depleted in ABCG5/G8-TgxLDLr-KO mice. Kinetic studies revealed similar 125I-apoB intermediate density lipoprotein/LDL fractional catabolic rates, but apoB production rates were decreased 37% in ABCG5/G8-TgxLDLr-KO mice. Proximal aortic atherosclerosis decreased by 52% (male) and 59% (female) in ABCG5/G8-TgxLDLr-KO versus LDLr-KO mice fed the Western/ezetimibe diet. Thus, increased biliary secretion, resulting from hepatic ABCG5/G8 overexpression, reduces atherogenic risk in LDLr-KO mice fed a Western diet containing ezetimibe. These findings identify distinct roles for liver and intestinal ABCG5/G8 in modulating sterol metabolism and atherosclerosis.