Hepatic lipase, high density lipoproteins, and hypertriglyceridemia

Hepatic lipase (HL) is a lipolytic enzyme that contributes to the regulation of plasma triglyceride (TG) levels. Elevated TG levels may increase the risk of developing coronary heart disease, and studies suggest that mutations in the HL gene may be associated with elevated TG levels and increased risk of coronary heart disease. Hepatic lipase facilitates the clearance of TG from the very low density lipoprotein (VLDL) pool, and this function is governed by the composition and quality of high density lipoprotein (HDL) particles. In humans, HL is a liver resident enzyme regulated by factors that release it from the liver and activate it in the bloodstream. HDL regulates the release of HL from the liver and HDL structure controls HL transport and activation in the circulation. Alterations in HDL-apolipoprotein composition can perturb HL function by inhibiting the release and activation of the enzyme. HDL structure may therefore affect plasma TG levels and coronary heart disease risk.     

Effects of continuous medroxyprogesterone acetate on lipoprotein metabolism in postmenopausal women receiving estrogen

Objective: To investigate the effects of medroxyprogesterone acetate (MPA) on the beneficial effects of estrogen therapy on lipid metabolism in postmenopausal women. Methods: Postmenopausal women were administered either conjugated equine estrogen (CEE) 0.625 mg daily for 3 months (Group 1) or CEE 0.625 mg in conjunction with MPA 2.5 mg (Group 2) or MPA 5.0 mg (Group 3) daily for 3 months. Plasma levels of cholesterol, triglyceride, lipoprotein lipids, apolipoproteins, sex steroid hormones and lecithin cholesterol acyltransferase activity (LCAT) were determined. Lipoprotein lipase (LPL) and hepatic triglyceride lipase (H-TGL) activities were measured in postheparin plasma. Changes in the lipid concentrations and enzymatic activities were evaluated in each group. Results: Total, low-density lipoprotein (LDL) cholesterol, apolipoprotein B concentrations and LCAT activity were all significantly reduced by treatment in the three groups. The levels of high-density lipoprotein (HDL), HDL2, and HDL3 cholesterol as well as the levels of apolipoprotein AI and AII were significantly elevated in groups 1 and 2. The mean decrease in these parameters was related to the dose of MPA. Levels of triglyceride in the HDL and HDL2 were significantly increased in group 1. The levels of triglyceride in plasma, very low density lipoprotein (VLDL), LDL, HDL3 and VLDL cholesterol and LPL activity were unaffected. H-TGL activity was significantly inhibited only in groups 1 and 2. MPA produced a dose-dependent increase in H-TGL activity. A significant negative correlation was observed between the HDL cholesterol concentration and H-TGL activity (r = 0.58 P < 0.001). Conclusions: The administration of MPA 2.5 mg and 5.0 mg did not adversely affect the changes in VLDL-LDL metabolism produced by estrogen. However, MPA has dose-dependent negative effects on HDL metabolism by increasing H-TGL activity and the 5.0 mg MPA interferes with the favorable effects on lipids of estrogen in postmenopausal women.     

茶多酚对实验性动脉粥样硬化兔脂蛋白脂酶、肝脂酶活性的影响及意义

目的:观察动脉粥样硬化(AS)发生发展过程中脂蛋白脂酶(LPL)、肝脂酶(HL)活性的变化及茶多酚(TP)的作用。方法:高脂食物AS模型兔口服茶多酚200μg·g^-1·d^-1,测定血浆中LPL、HL活性,同时用组织化学法检测动脉壁层组织中LPL活性、肝组织中HL活性。结果:AS组动脉粥样硬化病变血管壁与正常对照组血管壁组织中LPL活性差异无显著(P＞0.05);AS组肝组织中HL活性明显低于正常对照组(P＜0.05)。TP组肝组织中HL活性明显高于AS组(P＜0.05)、血浆中TC和LDL-c水平低于AS组(P＜0.05)、动脉粥样硬化斑块面积低于AS组(P＜0.05)。各组间血浆LPL、HL活性水平差异无显著(P＞0.05)。结论:茶多酚能增加实验性AS兔肝组织中HL脂酶活性,这一作用与降低血浆胆固醇水平和抗动脉粥样硬化密切相关。     

Genetic and environmental determinants of plasma high density lipoprotein cholesterol and apolipoprotein AI concentrations in healthy middle-aged men

The effects of common variants of cholesteryl ester transfer protein ( CETP ) ( Taq IB), hepatic lipase ( HL ) (−514C>T), lipoprotein lipase ( LPL ) (S447X) and lecithin cholesterol acyl transferase ( LCAT ) (S208T) on the determination of high density lipoprotein cholesterol (HDL-C) and apolipoprotein AI (apoAI) levels were examined in 2773 healthy middle-aged men participating in the second Northwick Park Heart Study. The extent of gene:gene, gene:smoking and gene:alcohol interactions were determined. For HDL-C levels, only CETP genotype was associated with significant effects ( p <0·0001), with the B2 allele being associated with higher levels in both smokers and non-smokers. This interaction was significant at the lowest tertile of TG, suggesting that TG levels were rate limiting. As previously reported, CETP , LPL and HL genotypes were all associated with significant effects on apoAI levels (all p <0·01), with carriers of the rare alleles having higher levels and with no evidence of heterogeneity of effects in smokers and non-smokers. LCAT genotype was not associated with significant effects on either trait. There was no significant interaction between any of the genotypes and alcohol consumption on either HDL-C or apoAI levels. All genotypic effects were additive for HDL-C and apoAI. Environmental and TG levels explained more than 20% and 5·5% of the variance in HDL-C and apoAI, respectively. The novel aspect of this finding is that genetic variation at these loci explained in total only 2·5% of the variance in HDL-C and 1·89% of the variance in apoAI levels. Thus despite the key roles played by these enzymes in HDL metabolism, variation at these loci, at least as detected by these common genotypes, contributes minimally to the variance in HDL-C and apoAI levels in healthy men, highlighting the polygenic and multifactorial control of HDL-C.     

Lipoproteins, post-heparin lipoprotein lipase and hepatic triglyceride lipase in patients with and without severe hyperlipemia caused by alcoholism

Because of the high incidence for development of a secondary hyperlipemia during chronic alcohol intake, this study was performed to look for a possible reason, why some patients produce severe hyperlipemia and other ones not. 15 male patients with chronic alcoholism (group I) who produce under influence of alcohol a secondary type-V hyperlipoproteinemia (type-V HLP) were compared with 15 male controls. Additionally, 8 male patients with chronic alcoholism (group II) who were normolipemic under alcohol abuse, and 7 male patients (group II) who had also produced type-V HLP under chronic alcohol abuse, but were teetotal since at least 6 months, were investigated. In comparison with controls, patients of group I showed significantly (p less than 0.01) increased plasma concentrations of very low-density lipoproteins (VLDL) and significantly decreased plasma concentrations of low-density lipoproteins (LDL), high-density lipoproteins2 (HDL2) and HDL3 (all p less than 0.01). Furthermore, the activities of postheparin lipoprotein lipase (LPL) and hepatic lipase (HTGL) were significantly decreased (both p less than 0.01). In patients of group III, the plasma concentrations of lipoproteins did not differ significantly from controls, but the activity of LPL was also significantly impaired (p less than 0.01), whereas the activity of HTGL was distinctly (p less than 0.01) increased. No significant difference between patients of group II and controls could be demonstrated. It is concluded that severe alcohol intake strongly impairs LPL in patients with chronic alcoholism. The pronounced increase of HTGL in patients of group III seems to protect these individuals from producing severe hyperlipemia under the influence of alcohol.     

Lipoprotein lipase activity in patients with combined hyperlipidaemia

The aetiology of familial combined hyperlipidaemia remains obscure, with both genetic and environmental factors contributing to the phenotype, which is frequently associated with premature coronary heart disease. We have studied lipoprotein lipase (LPL) activity and hepatic lipase (HL) activity in patients with coronary heart disease to determine whether variation in lipase activities contributes to this phenotype. Forty-one patients (mean age 50 years; 30 male) were selected on the basis of cholesterol levels above 6.5 mmol/l and triglyceride levels above 2.2 mmol/1, with apoprotein B values over the 90th percentile. There was a family history of premature coronary heart disease in 78% and a personal history in 64%, at mean age 44, the patient group therefore predominantly corresponded to the common definition of familial combined hyperlipidaemia, appropriate in the absence of molecular markers. None of the patients was diabetic; hypertension and smoking were not over represented. Blood samples were taken following intravenous administration of heparin (100IU/kg body wt), and LPL and HL activities were measured. Mean post-heparin LPL was significantly lower in patients than controls 10 min after heparin administration (2.98 ± 1.04 and 3.86 ± 0.93 mol ml^-1 h^-1, respectively, P = 0.001), and 37% patients had values below the 10th percentile of controls. Both male and female patients had significantly higher HL activities than their respective controls at 5, 10, 20 and 30 minutes postheparin. As expected, both female patients and controls had lower HL activities than males, although this sex difference did not reach statistical significance in the patient group. Mean lipid and lipoprotein results were: cholesterol 8.2 mmol/1; triglycerides 4.2 mmol/l; high-density lipoprotein cholesterol 0.90 mmol/1; apoprotein Al 122 mg/dl; apoprotein B 171 mg/dl; lipoprotein (a) 23 mg/dl (median 10 mg/dl). High-density lipoprotein cholesterol and triglycerides were negatively correlated (r = -0.26, P = 0.05). HL was significantly related to body mass index at all time points whereas the negative correlation between post-heparin LPL and body mass index was significant only 30 min after heparin administration. Post-heparin LPL was only weakly correlated with triglycerides 10 and 20 min after heparin administration. These lipid and lipoprotein results are clearly potentially atherogenic as indicated by the extent of premature coronary heart disease in the group described. A decrease in LPL activity may contribute to this pattern.Abbreviations FCHL familial combined hyperlipidaemia - CHD coronary heart disease - LPL lipoprotein lipase - HL hepatic lipase - HDL high-density lipoprotein - VLDL very low density lipoprotein; - apo apoprotein - TG triglyceride - BMI body mass index Correspondence to: M. Seed     

Evidence for deficiency of high density lipoprotein lecithin: cholesterol acyltransferase activity (alpha-LCAT) in fish eye disease

In a rare familial condition, fish eye disease, there is a low relative content of cholesteryl esters in the plasma high density lipoproteins (HDL) but a normal content of these lipids in the very low (VLDL) and low (LDL) density lipoproteins. Lecithin: cholesterol acyltransferase (LCAT) is the enzyme which mediates the esterification of free cholesterol in the plasma lipoproteins. In the present investigation, isolated HDL from our two fish eye disease patients were found to be excellent substrates during in vitro incubations with normal LCAT as present in lipoprotein depleted plasma from control subjects. Almost all free cholesterol of these HDL fractions became esterified and concomitantly the abnormally small fish eye disease HDL particles increased to a size in the range of that of normal HDL particles. Lipoprotein depleted plasma from fish eye disease, however, lacked the property of normal plasma to esterify the free cholesterol of HDL isolated from plasma of fish eye disease patients or control subjects. These results have led to the formulation of a new concept implying that two different LCAT activities exist in normal plasma. One of these activities, denoted alpha-LCAT, is specific for HDL (alpha-lipoproteins) and the other, beta-LCAT, is specific for VLDL-LDL (pre beta- and beta-lipoproteins). Fish eye disease according to this notion is classified as an alpha-LCAT deficiency in contrast to the classical LCAT deficiency which probably lacks both alpha- and beta-LCAT activities.     

内源性高甘油三酯血症患者血浆VLDL、LDL及HDL对血凝的影响

目的：研究内源性高甘油三酯血症(HTG)患血浆极低密度脂蛋白(VLDL)、低密度脂蛋白(LDL)及高密度脂蛋白(HDL)是否发生了氧化修饰及其对血凝的影响。方法：对2l例内源性高甘油三酯血症患与2l例年龄性别相近的正常人的血脂、脂质过氧化物进行了分析。用一次性密度梯度超速离心法分离血浆VLDL、LDL及HDL，测定这三种脂蛋白的234nm光吸收、相对电泳迁移率(REM)和硫代巴比妥酸反应物质(TBARS)，分别将这三种脂蛋白加入由正常人新鲜混合血浆构成的反应系统中，按试剂盒分别测定凝血酶原时间(PT)及活化部分凝血酶原时间(APIT)。结果：内源性HTG患血浆TG含量平均升高2．73倍，HDLC下降l.7l倍，同时LPO升高1．22倍;HTG组VLDL、LDL及HDL的REM、234nm光吸收值、TBARS含量均较对照组显增加(P＜0．01)，表明内源性HTG患血浆VLDL、LDL及LDL均发生了氧化修饰生成Ox—VLDL、Ox-LDL.PT及APTT在分别加入HTG组的VLDL、LDL及HDL后均比加入相应正常组脂蛋白明显缩短(P均＜0．05)。相关分析表明，HTG组血浆VLDL及HDL相对电泳迁移率(REM)与PT呈负相关(P＜0．01)。结论：HTG患血浆VLDL、LDL及HDL发生了氧化修饰，并使PT及APTT明显缩短。     

Glucose tolerance,plasma lipoproteins and tissue lipoprotein lipase activities in body builders

Summary Oral glucose tolerance, insulin binding to erythrocyte receptors, serum lipids, and lipoproteins, and lipoprotein lipase activities of adipose tissue and skeletal muscle were measured in nine body builders (relative body weight (RBW) 118±4%), eight weight-matched (RBW 120±5%) and seven normal-weight controls (RBW 111±3%). The body builders had 50% higher relative muscle mass of body weight (% muscle) and 50% smaller relative body fat content (% fat) than the two other groups (P<0.005). Maximal aerobic power was comparable in the three groups. In the oral glucose tolerance test (OGTT), blood glucose levels, and plasma insulin levels were lower (P<0.05) in the body builders than in weight-matched controls. Insulin binding to erythrocytes was similar in each group. On the basis of multiple linear regression analysis, 87% of the variation in plasma insulin response could be explained by body composition (% muscle and % fat) and .Plasma total cholesterol, low-density lipoprotein (LDL) cholesterol, and very low-density lipoprotein (VLDL) triglyceride concentrations were significantly lower in the body builders than in weight-matched controls. In comparison with the normal-weight group, the body builders had a lower total cholesterol level. High density lipoprotein (HDL) cholesterol, its subfractions (HDL₂ and HDL₃ cholesterol) and lipoprotein lipase (LPL) activities of adipose tissue and skeletal muscle were comparable in all three groups. Partial correlation analysis showed a positive relationship between plasma total triglyceride, total cholesterol and LDL cholesterol on the other hand and the % fat on the other.The results indicate that a shift in body composition from the adipose to the muscular type is associated with 1) lower glucose and insulin levels during the OGTT and 2) decrease in total and VLDL triglyceride and in total and LDL cholesterol levels but unchanged HDL cholesterol level. Thus, body builders are characterized by some metabolic features which decrease the risk of coronary heart disease. In contrast to aerobic training, body building does not influence HDL or its subfractions.     

Common haplotypes in five genes influence genetic variance of LDL and HDL cholesterol in the general population

We studied the association between common haplotypes in six relevant lipid metabolism genes with plasma lipid levels. We selected single-nucleotide polymorphisms (SNPs) in the cholesterol ester transfer protein (CETP), lipoprotein lipase (LPL), hepatic triglyceride lipase (HL), low-density lipoprotein cholesterol receptor (LDLR), apolipoprotein E (ApoE) and lecithin-cholesterol acyltransferase (LCAT) genes, and studied 732 individuals from 184 German families. Total cholesterol (TC), low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL) were similar to those reported in other European and American populations. Haplotypes derived from SNP combinations resulted in more significance and of a higher degree than did single SNPs in the genotype-phenotype association analysis. Reduction of the polygenic variance attributable to haplotypes was estimated using variance components analysis. Under the biometrical genetic model, allelic association of haplotypes was highly significant for HDL, LDL and the LDL/HDL ratio. The residual kinship correlation was reduced accordingly. The ApoE gene had a strong effect on trait variation; however, the other genes also contributed substantially. An epistatic interaction could not be demonstrated in this sample. The data are consistent with the notion that common genetic variants influence common traits.     

Lipoprotein Metabolism in Dogs and Cats

High-density lipoproteins (HDL) are the predominant lipoproteins in plasma of dogs and cats and are the major cholesterol-carrying particles. Two HDL subfractions are identifiable in dog: small, dense particles (equivalent to human HDL₃) and large, buoyant particles called HDL₁, which overlap in hydrated density with low-density lipoproteins (LDL). The HDL₁ are enriched in cholesterol and apolipoprotein (apo) E, and are prevalent in dogs fed high amounts of cholesterol and, or, saturated fat, when they are also referred to as HDL_c. Lipoproteins similar to human HDL₂ and HDL₃ are identifiable in feline plasma, along with trace HDL₁. Lipoprotein lipase (LPL), hepatic lipase (HL) and lecithin: cholesterol acyl transferase (LCAT) activities are present in dogs and cats. Both species lack significant cholesteryl ester transfer protein activity, and reverse cholesterol transport is probably accomplished by receptor-mediated hepatic uptake of HDL₁. Methods for the measurement of canine and feline plasma lipoprotein-cholesterol concentrations, apolipoprotein concentrations, and the activities of LPL, HL and LCAT have been developed. Together with oral and intravenous fat tolerance tests, these methods provide the basis for studying lipoprotein metabolism in cats and dogs.Originally presented at ECCP 95.     

Lipoprotein lipase deficiencies]

Lipoprotein lipase (LPL) is an enzyme which plays a major role in the metabolism of circulating triglyceride-rich lipoproteins. It hydrolyzes chylomicron and VLDL triglycerides, thereby delivering fatty acids to tissues for storage or oxidation. In order to gain insight into the molecular basis of LPL deficiency, the structure of the LPL gene (ten exons and nine introns spanning about 30 kb) is first set out in relation to the different domains of the LPL protein. There is a high sequence homology between the aminoacids of LPL and of other lipases, such as hepatic triglyceride lipase (HL) and pancreatic lipase (PL). The PL catalytic triad Ser132, Asp156, His241 is also present in LPL. Absence of LPL activity can result from absence of LPL protein synthesis (Brunzell class I), or from the synthesis of an LPL protein devoid of enzymatic activity consequently to a mutation (class II). LPL can also be unable to bind to endothelial cells--a defect combined with deficient enzymatic activity--(class III). Among the known mutations of the LPL gene (such as nonsense, frameshift, abnormality in intron-exon junction, deletion, duplication) resulting in pathological cases, the most frequent are punctual mutations located mainly in exons 4, 5 and 6, leading to the substitution of an aminoacid for another in essential domains of LPL. The combined deficiency LPL + HL has also been described. The study of the abnormalities of the LPL gene, known only since the years 1990-1991, allows not only to better understand the pathology of LPL deficiencies, but also to point out which aminoacids play a major role in LPL activity.     

重度子痫前期孕妇血清脂蛋白脂酶与血脂相关性的研究（附910例临床资料）

目的探讨脂蛋白脂酶（LPL）在子痫前期血脂代谢中的临床意义。方法回顾性分析310例重度子痫前期孕妇（子痫前期组）和300例健康晚孕妇女（晚孕组）、300例健康未孕育龄妇女（未孕组）的血脂代谢情况;检测26例子痫前期组、30例晚孕组和30例未孕组血IJPL、TG、HDL浓度。结果子痫前期组存在显著的高TG、低HDL血脂代谢异常,LPL与TG呈负相关、与HDL呈正相关。结论子痫前期存在显著的高血脂异常代谢,LPL可能通过参与异常血脂代谢而导致子痫前期发病。     

Ⅱb型高脂蛋白血症与脂蛋白脂酶基因内含子8HindⅢ多态性关联的研究

目的　探讨中国人 b型高脂蛋白血症与脂蛋白脂酶基因多态性是否有关联。方法　采用聚合酶链反应及限制性片段长度多态性方法对成都地区 10 3例 b型高脂蛋白血症患者及 12 9名血脂正常者脂蛋白脂酶基因 Hind 酶切位点的多态性及其与血脂、载脂蛋白水平的关联进行了研究。结果　 b型高脂蛋白血症患者和正常人均以 H+H+纯合子基因型为主 , b型脂蛋白血症组 H+等位基因频率较对照组增加 (0 .86 4 vs0 .70 5 ,P<0 .0 1) ;而 H-等位基因频率 b型高脂蛋白血症组则明显低于对照组(0 .136 vs0 .2 95 ,P<0 .0 1)。 b型高脂蛋白血症组 H+H+基因型者血浆甘油三酯水平明显高于 H+H-和 H- H- (P<0 .0 5 ,P<0 .0 1) ;血浆总胆固醇水平和 TG/ HDL- C也高于 H+H-和 H- H- (P<0 .0 5 )。H+H+基因型与 H+H-基因型者载脂蛋白 A 水平均低于 H- H-基因型者 (P<0 .0 1及 P<0 .0 5 )。正常对照组不同基因型亚组间的血脂及载脂蛋白水平差异均无显著性 (P>0 .0 5 )。结论　脂蛋白脂酶基因内含子 8Hind 酶切位点的多态性与中国人 b型高脂蛋白血症有一定关联。     

Evidence for the presence in human plasma of lecithin: cholesterol acyltransferase activity (beta-LCAT) specifically esterifying free cholesterol of combined pre-beta- and beta-lipoproteins. Studies of fish eye disease patients and control subjects

The present study was undertaken to test our hypothesis that two different lecithin: cholesterol acyltransferase (LCAT) activities exist in normal human plasma, one denoted alpha-LCAT esterifying the free cholesterol of high density lipoproteins (HDL) and the other denoted beta-LCAT acting on the free cholesterol of very low (VLDL) and low (LDL) density lipoproteins. Plasmas depleted of HDL were obtained by means of preparative ultracentrifugation. Incubation at 37 degrees C of these plasma fractions from control subjects and patients with fish eye disease resulted in esterification of the remaining free cholesterol of combined VLDL and LDL (pre-beta- and beta-lipoproteins) in the HDL depleted plasmas. The shapes of the cholesterol esterification rate curves were similar for whole and HDL depleted plasmas from both control subjects and fish eye disease patients. In crosswise mixed incubation experiments with isolated combined VLD and LDL and total lipoprotein depleted plasma from a control subject and a patient with fish eye disease, respectively, esterification of free cholesterol occurred. Incubation of isolated total lipoproteins in plasma from a patient with LCAT deficiency mixed with total lipoprotein depleted plasma from a fish eye disease patient as a source of LCAT caused cholesterol esterification but did not result in normalization of the LCAT deficiency HDL particles, while the amount of normal-sized LDL particles increased. The present results support the hypothesis that a beta-LCAT exists in normal human plasma.     

Different substrate specificities of plasma lecithin: cholesterol acyl transferase in fish eye disease and Tangier disease

Esterification of plasma free cholesterol is mediated by lecithin:cholesterol acyl transferase (LCAT). The free cholesterol of plasma high density lipoproteins (HDL) is considered to be the preferred substrate for LCAT. It therefore appeared as a paradox that plasma cholesterol esterification, both in vivo and in vitro, is normal in fish eye disease and Tangier disease, two familial conditions with extremely low plasma HDL levels. Fish eye disease plasma, however, was shown to have LCAT activity primarily acting on combined very low (VLDL) and low (LDL) density lipoproteins, denominated beta-LCAT, while it lacked LCAT activity esterifying HDL cholesterol (alpha-LCAT). Here we show that Tangier plasma, in contrast, has both alpha- and beta-LCAT. Thus, in both fish eye and Tangier diseases it is beta-LCAT that explains the apparent normal plasma cholesterol esterification. We also show that Tangier plasma, having alpha-LCAT activity, normalizes the low cholesteryl ester content as well as the abnormally small size of fish eye disease HDL particles during incubation.     

脂蛋白脂酶Ser447Ter基因多态性与动脉硬化性脑梗死的相关研究

目的研究脂蛋白脂酶（lipoprotein lipase，LPL）Ser447Ter基因多态性与动脉粥样硬化性脑梗死（atherosclerotic cerebral infarction, CI）发病的关系及其对血脂水平、颈动脉斑块的影响。方法对166例CI患者及72名健康成人采用聚合酶链反应-限制性片段长度多态性方法检测LPL-Ser447Ter基因多态性，颈动脉超声多普勒检查颈总动脉内膜中层厚度（intima-media thickness，IMT）和颈动脉斑块（carotid artery plaque，CAP）的形状及大小。结果CI组CG＋GG基因型甘油三酯（triglyceride，TG）含量比CC基因型明显降低（P=0．1301），高密度脂蛋白胆固醇（high density lipoprotein cholesterol，HDL-C）含量明显增高（P=0．007）；对照组CG＋GG基因型TG含量比CC基因型低（P=0．041）；CI组G等位基因频率低于对照组（P=0．014）；LPLSer447Ter基因多态性与颈总动脉IMT和CAP分级无明显相关。结论LPL Ser447Ter基因多态性与血脂变化及脑梗死的关系密切，G等位基因可能引起血TG降低、HDL-C升高；G等位基因可能是脑梗死的保护基因型．     

冠心病患者血浆LCAT水平与HDL亚类组成的关系

 目的： 探讨冠心病 (coronary heart disease, CHD) 患者血浆卵磷脂胆固醇酰基转移酶 (lecithin cholesterol acyltransferase, LCAT) 与高密度脂蛋白 (high-density lipoprotein, HDL) 亚类分布的关系。方法：采用双向电泳-免疫印记法分析了73例正常对照者和144例冠心病患者HDL亚类的组成、含量及分布特征,用酶联免疫法测定其LCAT浓度。冠心病患者按血浆LCAT浓度进行四分位数（19.22、36.39和55.32 mg/L）分层（Q1：LCAT<19.22 mg/L; Q2：19.22≤LCAT<36.39 mg/L; Q3：36.39≤LCAT<55.32 mg/L; Q4：LCAT≥55.32 mg/L）。结果：随着LCAT浓度的降低,冠心病患者血浆总胆固醇（TC）、甘油三酯（TG）水平和载脂蛋白B-100/A-I(apoB-100/A-I)比值呈增加趋势,高密度脂蛋白胆固醇（HDL-C）和apoA-I水平呈减少趋势。与最高四分位数组相比,第三、第二和最低四分位数组中preβ1-HDL含量增加,HDL2a和HDL2b含量减少 (P<0.05或P<0.01)。与正常TC组比较,高TC组LCAT浓度降低,且preβ1-HDL含量增加,HDL2a 和HDL2b含量减少(P<0.01)。直线相关和多元回归分析中发现,血浆LCAT水平与preβ1-HDL浓度呈负相关,与HDL2a和HDL2b浓度呈正相关。结论：CHD患者血浆HDL颗粒呈变小趋势,并且随着LCAT水平的降低,其HDL颗粒的变小程度更加明显。     

Effect of the APOC3 Sst I SNP on fasting triglyceride levels in men heterozygous for the LPL P207L deficiency

Lipoprotein lipase (LPL) plays a major role in triglyceride (TG)-rich lipoprotein catabolism. A mutation at codon 207 (P207L) in the exon 5 of the LPL gene has been associated with 50% reduction in postheparin plasma LPL activity and significant increase in plasma TG levels in heterozygous individuals with low HDL. However, heterogeneity in fasting TG concentrations among these carriers suggests that other factors may be involved in the expression of this hypertriglyceridemic state. Indeed, previous studies have shown that the rare S2 allele of the APOC3 Sst I polymorphism was associated with higher concentrations of TG levels in noncarriers of LPL defect. Therefore, we investigated the association of the APOC3 Sst I variant on fasting lipoprotein-lipid levels in a sample of 35 heterozygous men bearing the LPL P207L mutation. Genetic association analyses were performed using the two-genotype groups S1/S1 and S1/S2. The genotype S1/S2 group was characterized by greater plasma cholesterol (plasma-C, P=0.02), plasma-TG (P=0.04), very low-density lipoproteins (VLDL)-C (P=0.004), VLDL-TG (P=0.01), VLDL-apolipoprotein B (apoB) (P=0.001) levels and cholesterol/HDL-C ratio (P=0.008), as well as lower VLDL-TG/VLDL-apoB ratio compared to the S1/S1 genotype group. These results support an exacerbating effect of the APOC3 Sst I single-nucleotide polymorphism on fasting TG levels since a large number of smaller VLDL particles are observed in LPL-deficient men bearing the APOC3 S2 allele.     

Plasma and hepatic lipid profiles in furazolidone-treated rats.

Rats were treated orally with furazolidone (FZ) at doses of 50, 100, and 200 mg/kg body weight for three consecutive days. The parameters determined in plasma included: total cholesterol, high density (HDL) cholesterol, low-density (VLDL+LDL) cholesterol, triglycerol (TAG), phospholipids (PL), and lipoprotein lipase. In the liver, cholesterol, TAG and phospholipid concentrations were measured. At the lowest dose used, no statistically significant effect on any of these parameters in plasma or liver was observed. The drug, dose-dependently, increased the concentrations of total cholesterol, VLDL cholesterol, TAG and PL in plasma. The activity of lipoprotein lipase was significantly decreased by FZ by about 45%. The hepatic cholesterol concentration was not significantly affected by any of the doses used. However, doses of 100 and 200 mg/kg produced fatty infiltration in the liver and significantly increased TAG level. The highest dose also decreased PL concentration.