高脂血症时血清二乙基对硝基苯磷酸酯酶活性的变化

目的 :研究tritonWR 13 3 9致小鼠高脂血症时血清二乙基对硝基苯磷酸酯酶 (ParaoxonaseI ,PON 1)活性的变化及PON 1活性与血浆脂质含量之间的关系。方法 :在小鼠尾静脉注射tritonWR13 3 9后的 3h ,6h ,12h ,2 4h ,48h ,72h ,眼球摘除术取血 ,用酶标法测定小鼠血浆总胆固醇 (TC) ,甘油三酯 (TG ) ,高密度脂蛋白 -胆固醇 (HDL -C) ,载脂蛋白AI (ApoAI) ,载脂蛋白B (ApoB含量 ) ,并计算出ApoAI/ApoB ,HDL -C/TC比值 ,用分光光度计法测定PONI活性。结果 :TritonWR 13 3 9尾静脉注射后 3h ,小鼠血浆TC和TG含量即急剧增高 ,与对照组相比 ,P <0 .0 1,分别在注射后 2 4h和 3h达到峰值 ,随后逐渐下降 ,其中血浆TG含量在注射后 48h即恢复正常水平。tritonWR13 3 9尾静脉注射后 3h ,小鼠血浆HDL -C和ApoB含量急剧增高 ,与对照组相比 ,P <0 .0 5,分别在注射后 2 4h和 6h达到峰值 ,随后逐渐下降 ,分别在注射后 48h和 72h恢复正常水平。tritonWR13 3 9尾静脉注射后 3h ,小鼠血浆ApoAI含量即急剧降低 ,与对照组相比 ,P <0 .0 5,随后逐渐增高 ,在注射后 6h即恢复正常水平。tritonWR 13 3 9尾静脉注射后 3h ,小鼠血浆ApoAI/ApoB和HDL-C/TC比值减少 ,与对照组相比 ,P <0 .0 1,随后逐渐增高 ,其中ApoAI/ApoB比值在 72h恢复     

冠心病患者血清对氧磷酶活性的测定

目的探讨冠心病患者血清对氧磷酶1活性及其与冠心病之间的关系。方法选择冠状动脉造影确诊的冠心病患者106例和非冠心病组62例,用乙酸苯酯法和比色法分别测定两组血脂、血清对氧磷酶1活性、超氧化物歧化酶及丙二醛含量,并进行对比分析。结果冠心病组血清中对氧磷酶1活性和超氧化物歧化酶水平分别为113±64μkat/L和43.8±8.2 kU/L,均较对照组降低(134±72μkat/L和63.4±5.7 kU/L)(P<0.05);而丙二醛含量较对照组升高(9.4±1.8μmol/L比4.1±0.5μmol/L,P<0.01)。对氧磷酶1活性与高密度脂蛋白和超氧化物歧化酶水平呈正相关,与丙二醛水平呈负相关。冠状动脉狭窄者对氧磷酶1活性较无狭窄者明显减低(P<0.001),2、3支血管病变者较1支血管病变者对氧磷酶1活性降低(P<0.05)。结论冠心病患者血清对氧磷酶1活性降低,低对氧磷酶1活性与冠心病严重程度有关。     

Antioxidant enzymes and paraoxonase show a co-activity in preserving low-density lipoprotein from oxidation

Oxidative modification of low-density lipoprotein in the artery wall plays a crucial role in the development of atherosclerosis. This physiopathological mechanism is clearly inhibited by high-density lipoprotein possibly via paraoxonase enzyme activity, present in high-density lipoprotein. In this study we determined the in vitro susceptibility of low-density lipoprotein to oxidation and the effect of various factors, such as paraoxonase phenotypes, on this process. Low-density lipoprotein from healthy volunteers (n=66) was isolated using the precipitant reagent and the oxidation was evaluated by measuring the malonyl dialdehyde and diene levels. Low-density lipoprotein cholesterol and phospholipid, vitamin E, serum cholesterol, high-density lipoprotein and low-density lipoprotein cholesterol levels, and erythrocyte antioxidant enzymes were also determined. There was no difference among the parameters with regard to gender. Low-density lipoprotein samples obtained from subjects with the AA allele were more prone to oxidation, as observed by their higher stimulated conjugated diene (P=0.041) and thiobarbituric acid-related substance (P=0.042) levels, than samples from subjects with AB or BB alleles. The subjects with the BB allele had higher superoxide dismutase (P=0.021) and catalase (insignificant increase) activities, while their conjugated diene (P=0.000) levels were lower. In conclusion, our results revealed that the high low-density lipoprotein oxidation is related to the high low-density lipoprotein cholesterol content and low phospholipid content. The present study demonstrated an increase in superoxide dismutase and catalase activities, asl well as PON1 activities, in subjects with the BB allele. Since these enzymes all show activity against low-density lipoprotein oxidation, we propose that future investigations on atherosclerotic processes should address PON1 polymorphism as well as PON1 and other antioxidant enzymes. Received: 7 May 2001 / Accepted: 14 December 2001     

Paraoxonase 1 status in the Thai population

Human serum paraoxonase 1 (PON1), a high-density lipoprotein (HDL)-associated enzyme, has been shown to reduce the oxidation of low-density lipoprotein (LDL) and HDL by degrading lipid peroxides. This property of PON1 accounts for its ability to protect against atherosclerosis. In this study, we identified four polymorphisms in both the coding (L55M and Q192R) and regulatory regions (T-108C and G-909C) of the human PON1 gene in 202 healthy Thai individuals and investigated the influence of these polymorphisms on serum PON1 activity towards three substrates, namely, paraoxon, phenylacetate and diazoxon. The PON1 L55M, Q192R and G-909C polymorphisms significantly affected the variation in serum PON1 activity towards paraoxon. Serum PON1 activity towards paraoxon was significantly different among the genotype groups, as follows: 55LL > 55LM/55MM, 192RR > 192QR > 192QQ and –909CC > –909CG > –909GG. The PON1 Q192R and G-909C polymorphisms also influenced the variation in serum PON1 activity towards diazoxon but in the opposite direction to the activity towards paraoxon. Only the PON1 L55M polymorphism was associated with significant variation in serum PON1 activity towards phenylacetate while the PON1 T-108C polymorphism had no significant effect on serum PON1 activity towards any substrate. We also found linkage disequilibrium among the polymorphic sites, including Q192R versus L55M, Q192R versus T-108C and Q192R versus G-909C. Serum PON1 activity towards both paraoxon and phenylacetate, but not diazoxon, was positively correlated with HDL cholesterol (HDL-C) and apo AI concentrations. None of the PON1 polymorphisms significantly affected serum lipid, lipoprotein or apolipoprotein concentrations. Our findings suggest that the physiological relevance of the PON1 polymorphisms is that they are associated with significant differences in serum PON1 activity, and the impact of PON1 polymorphisms on this activity is substrate-dependent.     

Oxidized to non-oxidized lipoprotein ratios are associated with arteriosclerosis and the metabolic syndrome in diabetic patients

Background and aimType 2 diabetic patients have a greater prevalence of the metabolic syndrome, oxidative stress and accelerated atherosclerosis, compared to non-diabetics. We examined the association between biomarkers of lipid peroxidation and the presence of atherosclerosis and the metabolic syndrome in diabetic patients.Methods and resultsWe studied oxidized LDL (OxLDL), OxLDL/LDL, OxLDL/HDL, lipoperoxides, autoantibodies against OxLDL (OxLDL-Ab), diene formation of LDL (lag phase), vitamin E, vitamin E/cholesterol and PON1 polymorphisms (−108C > T, 55T > A, and 192A > G) in 166 non-smoking type 2 diabetic patients, 119 fulfilling the criteria for the metabolic syndrome, 73 with atherosclerosis and 93 without atherosclerosis. Patients with macrovascular disease had higher values of OxLDL/LDL (11%; P = 0.016), OxLDL/HDL (18%; P = 0.024) and OxLDL-Ab (12%; P = 0.046). OxLDL/LDL and OxLDL/HDL were correlated with the number of components of the metabolic syndrome (P < 0.001). PON1 polymorphisms were not associated to LDL oxidation markers, only PON1 (−108TT) was weakly associated with higher OxLDL-Ab concentrations (22%; P = 0.040) in patients with atherosclerosis.ConclusionOxLDL/LDL, OxLDL/HDL and OxLDL-Ab are the most useful clinical parameters of lipoprotein oxidation for discriminating the presence of macrovascular disease in diabetic patients. The presence of the metabolic syndrome in these patients is also associated with an increase in the oxidized lipoprotein ratios.     

冠心病及2型糖尿病合并冠心病与对氧磷酯酶192Gln/Arg基因多态性的相关性研究

为探讨冠心病(CHD)及2型塘尿病(DM)合并CHD与对氧磷酯酶(PON1)192G1n／Arg基因多态性的关系，采用多聚酶链反应—限制性片段长度多态性(PCR—RFLP)法检测了104例查体健康者(对照组)和76例CHD、96例2型DM合并CHD患者的PONl—192位点的多态基因型；同时测量其体重指数(BMI)，检测总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL—C)、低密度脂蛋白胆固醇(LDL—C)、载脂蛋白A I(ApoA I)、载脂蛋白B(Apo B)。结果显示，PONl—192位点QQ、QR、RR基因型及Q、R等位基因频率在2型DM合并CHD组与对照组比较均有显著性差异(P＜0．05、＜0．01)；但CHD组与对照组比较无显著性差异(P＞0．05)。中国人与白种人PON1-192位点基因型及等位基因频率比较有显著性差异(P＜0．01)。含R等位基因的基因型QR、RR是2型DM合并CHD的独立危险因素。提示PONl—192G1n／Arg基因多态性与2型DM合并CHD有相关性，与CHD无相关性。     

A case control study on HDL associated PON1 enzyme level in Northern Indian type 2 diabetes mellitus patients

Aim

To evaluate the serum paraoxonase 1 activity and determine its association with duration in type 2 Diabetes mellitus patients.

2型糖尿病合并冠心病患者对氧磷酶1基因多态性分析

目的探讨对氧磷酶1(PON1)基因多态性与2型糖尿病合并冠心病的相关性。方法使用变性高效液相色谱分析方法检测了202例2型糖尿病合并冠心病患者、177例单纯2型糖尿病患者和206名健康对照者;共检测了PON1基因G-126C、L55M和Q192R 3个多态性的基因型,比较分析3组间各基因型和等位基因频率分布的差异。结果 2型糖尿病合并冠心病组的Q192R位点R等位基因频率明显高于对照组(67.1%比60.2%,P=0.024),其他位点在各组间差异无统计学意义。结论PON1基因Q192R位点R等位基因与2型糖尿病合并冠心病发病相关。     

HDL anti-oxidant function associates with LDL level in young adults

Objectives

The primary objective was to evaluate predictors of HDL anti-oxidant function in young adults.

Background

High-density lipoprotein (HDL) cholesterol is considered a protective factor for cardiovascular disease (CVD). However, increased levels are not always associated with decreased cardiovascular risk. A better understanding of the importance of HDL functionality and how it affects CVD risk is needed.

Methods

Fifty non-Hispanic white subjects from the Testing Responses on Youth (TROY) study were randomly selected to investigate whether differences in HDL anti-oxidant function are associated with traditional cardiovascular risk factors, including carotid intima media thickness (CIMT), arterial stiffness and other inflammatory/metabolic parameters. HDL anti-oxidant capacity was evaluated by assessing its ability to inhibit low-density lipoprotein (LDL) cholesterol oxidation by air using a DCF-based fluorescent assay and expressed as a HDL oxidant index (HOI). The associations between HOI and other variables were assessed using both linear and logistic regression.

Results

Eleven subjects (25%) had an HOI ≥ 1, indicating a pro-oxidant HDL. Age, LDL, high sensitivity C-reactive protein (hsCRP), and paraoxonase activity (PON1), but not HDL, were all associated with HOI level in univariate linear regression models. In multivariate models that mutually adjusted for these variables, LDL remained the strongest predictor of HOI (0.13 increase in HOI per 1 SD increase in LDL, 95% CI 0.04, 0.22).Atherogenic index of plasma, pulse pressure, homocysteine, glucose, insulin, CIMT and measurements of arterial stiffness were not associated with HOI in this population.

Conclusions

These results suggest LDL, hsCRP and DBP might predict HDL anti-oxidant function at an early age.