刺梨汁对金黄地鼠的抗动脉粥样硬化作用

为寻找有效抗脂蛋白氧化剂防治动脉粥样硬化 ,在建立金黄地鼠的动脉粥样硬化模型过程中 ,分别补充维生素C、维生素E及刺梨汁 ,分析血浆脂质、抗氧化剂水平 ,低密度脂蛋白氧化易感性及动脉粥样硬化发生程度的变化。结果发现 ,高胆固醇饲料喂养 10周后 ,各组实验动物血脂水平均升高 ,且伴有主动脉粥样硬化斑块的形成 ;各抗氧化干预组血浆中相应的抗氧化剂水平均显著升高 ,低密度脂蛋白抗氧化性增强 (维生素C组、维生素E组、刺梨汁组和对照组的低密度脂蛋白氧化延迟时间分别为 2 2 1± 5 6min、2 2 2± 6 0min、2 48± 48min和 181± 47min ,组间比较P <0 .0 5 ) ,动脉粥样硬化斑块面积均显著减少 (维生素C组、维生素E组、刺梨汁组和对照组粥样硬化斑块程度分别为 2 .6 3%± 1.35 %、2 .44 %± 1.47%、1.43%± 0 .92 %和 5 .6 2 %± 1.2 8% ,组间比较P <0 .0 0 1) ,以刺梨汁组减少最明显。相关分析表明 ,主动脉粥样硬化面积程度与低密度脂蛋白氧化延迟时间呈显著负相关 (r =- 0 .42 ,P <0 .0 5 ) ,低密度脂蛋白氧化延迟时间与血浆维生素E水平呈正相关 (r=0 .36 ,P <0 .0 5 )。结果提示 ,抗氧化剂改善低密度脂蛋白氧化易感性 ,降低动脉粥样硬化的发生。     

银杏叶提取物及其合剂对饲胆固醇兔动脉粥样硬化的作用

目的：研究银杏叶提取物和银杏叶提取物合剂（银杏叶提取物＋维生素Ｅ＋Ｌ－精氨酸＋牛磺酸,２：１：２：２．５）对饲胆固醇兔动脉粥样硬化的防治作用。方法采用饲１％胆固醇兔形成动脉粥样硬化为模型,观察银杏叶提取物和银杏叶提取物合剂对饲胆固醇兔胸主动脉动脉粥样硬化斑块面积百分比及对血浆丙二醛和一氧化氮含量的影响。结果银杏叶提取物合剂（１－３ｍｇ／ｋｇｐｅｒｄａｙ）和银杏叶提取物（０．５ｍｇ／ｋｇｐｅｒｄａｙ     

银杏叶提取物对高脂饮食所致血管内皮功能损伤的保护及与对氧磷酶活性的关系

为探讨银杏叶提取物对高脂血症所致血管内皮功能损伤的保护作用及其机制 ,在大鼠高脂血症模型对比观察了银杏叶提取物和维生素E的作用。结果发现 ,大鼠高脂血症导致血管内皮依赖性舒张反应和非内皮依赖性舒张反应、血清一氧化氮浓度和对氧磷酶活性显著降低、血清丙二醛浓度显著升高。银杏叶提取物 [2 5mg (kg·d) ]或维生素E[10 0mg (kg·d) ]对高脂血症无明显抑制作用 (P >0 .0 5 ) ,但显著保护血管舒张功能和一氧化氮的血清浓度及对氧磷酶的活性 ,阻止了丙二醛的升高。在对照组、高脂组、银杏叶提取物和维生素E组 ,一氧化氮浓度(mmol L)分别为 5 .16± 1.3、3.35± 1.0 7、5 .0 5± 1.4 1和 4 .91± 1.6 5 (高脂组比对照组 ,P <0 .0 5 ;高脂组比银杏叶提取物和维生素E组 ,P <0 .0 5 ) ;内皮依赖性舒张反应分别为 95 .1%± 19.8%、4 7.1%± 15 .0 %、81.8%± 9.3%和 76 .2 %± 11.3% (高脂组比对照组 ,P <0 .0 1;高脂组比银杏叶提取物和维生素E组 ,P <0 .0 1) ;非内皮依赖性舒张反应分别为 98.2 %± 3.6 %、5 6 .7%± 7.9%、85 .8%± 7.2 %和 83.6 %± 4 .9% (高脂组比对照组 ,P <0 .0 1;高脂比银杏叶提取物和维生素E组 ,P <0 .0 1) ;对氧磷酶活性 (kU L)分别为 :18.0 %± 7.2 %、7.9%± 3.7%、16 .5 %     

血管内皮生长因子165对实验性兔动脉粥样硬化斑块形成的影响

目的观察血管内皮生长因子165对动脉粥样硬化斑块形成与发展的影响。方法利用高胆固醇饲料复制动脉粥样硬化兔模型。15只兔随机分为正常对照组、高胆固醇组和血管内皮生长因子组。42天时处死动物,截取胸主动脉进行计量组织学及免疫组织化学分析。结果正常对照组、高胆固醇组和血管内皮生长因子组的斑块面积(0%比1.81%±0.61%比24.12%±3.58%)、斑块周径(0比6.05%±1.62%比25.71%±1.97%)以及斑块最大厚度(0比0.06mm±0.002mm比0.16mm±0.007mm)均存在显著差异(P<0.05)。3组CD34阳性细胞数(cellsmm2)分别为0、12.35±2.02和61.15±7.55(P<0.05)。电镜显示新生血管与动脉粥样斑块相邻,新生血管腔内可见淋巴细胞。血管内皮生长因子组CD34阳性细胞数与斑块面积之间呈正相关(r=0.989,P<0.001)。结论血管内皮生长因子165能促进兔动脉粥样硬化斑块的形成与发展。     

脂肪分化相关蛋白在兔动脉粥样硬化模型中的表达

研究脂肪分化相关蛋白与动脉粥样硬化发生和发展的关系。使用高胆固醇饲料喂养新西兰白兔 12周 ,复制动脉粥样硬化模型。用生物化学法测定血清总胆固醇、低密度脂蛋白胆固醇、高密度脂蛋白胆固醇、甘油三酯及动脉壁胆固醇含量 ;苏丹Ⅳ染色观察主动脉斑块面积 ;HE染色观察主动脉及肝脏的病变 ;免疫组织化学法观察脂肪分化相关蛋白在主动脉病变区及肝脏中的表达。结果发现 ,喂高胆固醇饲料的动物血清总胆固醇、低密度脂蛋白胆固醇、甘油三酯及动脉壁胆固醇含量显著升高 ,主动脉病变面积为 4 0 .1%± 7.3% ,脂肪分化相关蛋白在主动脉动脉粥样硬化病变区免疫组织化学染色呈强阳性 ,在肝脏中染色呈阴性。喂高胆固醇饲料能成功复制出兔动脉粥样硬化模型。脂肪分化相关蛋白在兔动脉粥样硬化病变中表达明显增高 ,提示脂肪分化相关蛋白与动脉粥样硬化的发生发展密切相关     

辛伐他汀的调脂及抗动脉粥样硬化作用

采用食饵性兔动脉粥样硬化为模型 ,以舒降之为阳性对照药 ,研究辛伐他汀的调脂及抗动脉粥样硬化作用。将 5 6只雄性新西兰兔 (体重 1.96± 0 .16kg)随机分为对照组 (颗粒饲料 12 0～ 15 0g d ,n =14 )、动脉粥样硬化模型组 [颗粒饲料 +胆固醇 0 .5g (kg·d) ,n =14 ]、舒降之组 [颗粒饲料 +胆固醇 +舒降之片 5mg (kg·d) ,n =14 ]和辛伐他汀组 [颗粒饲料 +胆固醇 +辛伐他汀片 5mg (kg·d) ,n =14 ]。在实验前、实验第 8、12周末分别测定血清总胆固醇和甘油三酯 ,并分别处死 7只兔取主动脉染色测定主动脉粥样硬化斑块面积。结果发现 ,与对照组相比 ,第8、12周末时动脉粥样硬化模型组血清总胆固醇和甘油三酯均显著增高 ,总胆固醇第 8周末为 14 .86± 4 .15mmol L ,第 12周末时为 18.8± 7.6 8mmol L ;甘油三酯第 8周末为 1.83± 0 .4 9mmol L ,第 12周末时为 2 .5 9± 0 .6 3mmol L。第8、12周末时对照组主动脉粥样硬化斑块面积均为零 ,而动脉粥样硬化模型组主动脉粥样硬化斑块面积分别为 35 .2 9%± 9.4 1%和 4 2 %± 9.6 9% ;辛伐他汀组和舒降之组血清总胆固醇和甘油三酯及主动脉粥样硬化斑块面积均显著低于同期动脉粥样硬化模型组 (P <0 .0 1) ,且该两组同期总胆固醇和甘油三酯及主动脉粥样硬化斑块面     

斑块内血管生成在兔动脉粥样硬化斑块发生发展中的作用

目的观察斑块内血管生成对兔动脉粥样硬化斑块形成与发展的影响。方法用高胆固醇饲料复制动脉粥样硬化兔模型。15只日本大耳白兔随机分为3组:A组,阴性对照组,仅给普通饲料喂养,B、C组给高胆固醇饲料喂养3周,A组及B组肌注白蛋白(2μg/kg)(0d),C组肌注血管内皮生长因子(VEGF1652μg/kg),继续以前饲养方式3周处死动物,截取胸主动脉进行计量组织学及免疫组织化学分析,测定不同组别不同时间点兔血清白细胞介素8(IL8)浓度和血脂浓度。结果(1)斑块面积(A组0,B组1.81%±0.61%,C组24.12%±3.58%)、斑块周径(A组0,B组6.05%±1.62%,C组25.71%±1.97%)及斑块的最大厚度(A组0,B组0.06mm±0.002,C组0.16mm±0.007mm),各组间比较有显著差异(P<0.05)。(2)新生血管的密度(CD34阳性细胞数细胞数/mm2(cells/mm2)A组0,B组12.35±2.02,C组61.15±7.55)各组之间比较有显著差异(P<0.05)。(3)电镜显示:新生血管与动脉粥样斑块相邻,新生血管腔内可见淋巴细胞。(4)血清IL8浓度(+21d时A组[0.05±0.006]pg/ml,B组[0.808±0.308]pg/ml,C组[15.72±4.31]pg/ml)各组间相比有显著差异。(5)此时血清胆固醇浓度B,C两组相比无显著差异。结论斑块内血管生成是动脉粥样斑块的重要病理特征,这个过程可能与炎性反应有关。     

氟伐他汀对高脂饮食兔动脉粥样硬化发生早期干预作用

目的　观察氟伐他汀对高脂饮食兔动脉粥样硬化发生的早期干预作用。方法　健康纯种新西兰白兔40只 ,随机等分为实验组 (高脂饮食 +氟伐他汀10mg·kg-1·d-1)和对照组 (高脂饮食 )。分别于实验前及实验第 2、4、6、8周每组随机抽取 4只 ,兔耳中动脉抽血测血脂水平 ,气栓法处死测定主动脉内斑块面积占内膜总面积的比例。结果　实验组和对照组两组实验前的总胆固醇、低密度脂蛋白胆固醇及主动脉斑块面积占内膜总面积的比例均无差异 ,虽然随着时间的推移 ,两组的总胆固醇、低密度脂蛋白胆固醇及主动脉斑块面积占内膜总面积的比例均上升 ,但从实验第 2周以后的总胆固醇、低密度脂蛋白胆固醇及主动脉斑块面积占内膜总面积的比例治疗组均低于对照组 (P均小于 0 .0 5 )。结论　氟伐他汀能早期干预高脂饮食兔动脉粥样硬化的发生、发展     

黄精多糖的降血脂及抗动脉粥样硬化作用

目的探讨黄精提取物黄精多糖对高脂血症实验兔血脂及动脉粥样硬化形成的影响及其可能的发病机制。方法将40只新西兰兔随机分为对照组(饲以普通饲料)、高脂组(饲以胆固醇饲料)、血脂康组(饲以胆固醇饲料+血脂康)和黄精多糖组(饲以胆固醇饲料+黄精多糖),分笼喂养8周。分别于实验开始时、第4周末和第8周末,采用酶法检测血清总胆固醇、甘油三酯、低密度脂蛋白胆固醇和脂蛋白(a)含量。第8周末处死动物,光镜观察主动脉粥样硬化形成情况。结果实验前各组血清检测指标无明显差异。实验第4周高脂组、血脂康组和黄精多糖组血清总胆固醇(分别为10.5±1.6mmolL、11.1±2.0mmolL和11.2±1.9mmolL)、低密度脂蛋白胆固醇(分别为9.28±1.83mmolL、10.04±2.04mmolL和10.7±1.89mmolL)、脂蛋白(a)(分别为649±113mgL、713±101mgL和641±108mgL)均显著高于对照组[血清总胆固醇为1.4±0.3mmolL、低密度脂蛋白胆固醇为1.21±0.19mmolL、脂蛋白(a)为63.3±11.2mgL,P<0.01]。实验第8周,黄精多糖组血清总胆固醇(5.9±2.0mmolL)、低密度脂蛋白胆固醇(4.35±1.64mmolL)和脂蛋白(a)(45.3±14.0mgL)显著低于实验第4周水平(P<0.01)。黄精多糖组主动脉内膜泡沫细胞形成的发生率(20%)显著低于高脂组(发生率为100%,P<0.01)。结论黄精多糖具有降脂和抗实验性动脉粥样硬化形成的作用,其作用机理有待进一步探讨。     

NARC-1蛋白在新西兰兔动脉粥样硬化病变中的表达

目的 探讨NARC-1在新西兰兔动脉粥样硬化病变血管壁中的表达.方法 健康纯种雄性新西兰白兔16只,适应性喂养1周后,随机分为对照组和高胆固醇组,每组8只;对照组给予普通颗粒饲料喂养,高胆固醇组给予高胆固醇饲料(2%胆固醇)喂养;两组动物于8周末安乐处死.全自动生化分析仪测定兔血浆中甘油三酯、总胆固醇、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇含量,计算动脉粥样硬化指数、高密度脂蛋白胆固醇/低密度脂蛋白胆固醇比值.苏丹Ⅳ染色测量兔主动脉粥样硬化病变面积.油红O染色及HE染色观察兔主动脉病理组织学改变,并进行病理形态学定量分析.免疫组织化学法与免疫印迹法检测兔主动脉组织NARC-1蛋白的分布及表达水平.结果 8周末,高胆固醇组兔血浆总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇和、动脉粥样硬化指数水平明显升高,而高密度脂蛋白胆固醇/低密度脂蛋白胆固醇比值明显降低.高胆固醇组出现了明显的动脉粥样硬化病变,主动脉内膜面粥样硬化病变面积为27.41%±2.12%,与对照组(0.51%±0.20%)相比差异显著(P<0.05).病理组织学显示高胆固醇组兔主动脉内膜明显增厚,内膜/中膜厚度比明显增大;油红O染色光镜下显示,高胆固醇组兔主动脉内皮下斑块内泡沫细胞呈橘红色,对照组主动脉内膜未见明显着色;HE染色光镜下显示,高胆固醇组主动脉内膜显著增生,形成明显斑块,斑块中纤维组织增生,可见大量泡沫细胞,胞核较小,胞浆内含有大量脂质空泡,对照组内膜薄且结构完整.免疫组织化学检测发现高胆固醇组兔主动脉NARC-1蛋白表达明显,染色呈强阳性,且群集于内膜斑块处;在高倍镜下,NARC-1蛋白主要分布在泡沫细胞的胞浆和胞膜,而在对照组兔血管壁组织中未见表达.免疫印迹检测发现高胆固醇组兔主动脉NARC-1蛋白呈高表达,而对照组兔血管壁组织未见表达.结论 新西兰兔的主动脉粥样硬化病变处NARC-1蛋白表达明显,其主要分布在泡沫细胞的胞浆和胞膜中,正常对照组兔主动脉血管壁组织未检测到NARC-1蛋白.提示NARC-1/PCSK9是影响动脉粥样硬化病变形成与发展的重要因素.     

Antioxidative effects of Choi-oki-to and its ability to inhibit the progression of atheroma in KHC rabbits

Agents which inhibit the oxidative modification of low density lipoprotein (LDL) have been thought to be helpful in preventing the formation of atherosclerotic lesions; the so called "oxidation hypothesis". To test this hypothesis, we examined the antioxidative activities of 127 Kampo medicines in vitro and their inhibitory effects on the development of atheromatous plaque formation in KHC rabbits, a model of spontaneous familial hypercholesterolemia. Some of the 127 Kampo medicines showed scavenging or antioxidative effects equal to or stronger than those of probucol in vitro. Choi joki to, which had the strongest antioxidative effects on LDL in vitro, was chosen for a study in vivo. After 24 weeks, 1 g/kg of Choi joki to successfully inhibited the progression of atherosclerotic lesions in KHC rabbits (P < 0.01). Further investigations regarding the antioxidative effects of Kampo medicines are expected.     

Effects of garlic extract on oxidant/antioxidant status and atherosclerotic plaque formation in rabbit aorta

BACKGROUND AND AIM: The results of a number of studies suggest that garlic (or garlic extracts) may have favourable effects against the development of atherosclerosis. The aim of this study was to investigate the effects of garlic extract supplementation on oxidant/antioxidant status and atherosclerotic plaque formation in rabbit aortic tissue. METHODS: AND RESULTS: Twenty-two male New Zealand White rabbits were fed a cholesterol-supplemented diet (0.5 g/Kg/day) and nine control rabbits a regular diet for four months. At the end of this period, atherosclerotic plaque formation and antioxidant activity were measured in the aortic tissue of the controls and seven of the cholesterol-fed animals. Of the remaining 15 experimental animals, seven were fed normal laboratory diet and eight a normal diet plus garlic extract (1.5 ml/Kg/day) for a further three months before atherosclerotic plaque formation and antioxidant activity were measured in the aortic tissue of both groups. The cholesterol-fed animals showed a significantly impaired antioxidant system associated with increased plaque formation. However, garlic extract supplementation significantly improved antioxidant status and reduced the plaque surface area. CONCLUSIONS: In this experimental model, garlic extract dietary supplementation activated the antioxidant system and decreased peroxidation in aortic tissue. There was also a reduction in atherosclerotic plaque area. Although further studies are required to elucidate the mechanisms involved, the protective activity of garlic extract may be due to its antioxidant properties.     

Effects of Ginkgo biloba extract on cell proliferation, cytokines and extracellular matrix of hepatic stellate cells.

BACKGROUND/AIMS: Hepatic fibrosis is the common wound-healing response to chronic liver injury. Ginkgo biloba extract (GbE) has been indicated to reverse hepatic fibrosis and exhibit therapeutic effects both in vitro and in vivo. This study aimed to investigate the underlying mechanism of GbE using HSC-T6 cells, a subline of hepatic stellate cells (HSC) as a model. METHODS: HSC-T6 cells were seeded into six-well plates and allowed to attach overnight. After exposure to different concentrations of GbE761 for 24 or 48 h, cell cycle analysis, semiquantitative RT-PCR, Western blotting analysis and analysis of ECM secretion were performed. RESULTS: It was revealed that GbE (1, 10, 100, 500 mg/l) suppressed HSC proliferation and caused G0/G1 phase arrest in a concentration-dependent manner. RT-PCR and Western blot assays were applied to detect the decline of transforming growth factor beta1(TGF-beta1) and connective tissue growth factor (CTGF) in both mRNA and protein levels after GbE treatment in HSC-T6 cells for 24 or 48 h. Meanwhile, GbE inhibited the synthesis of type I and type III collagens. Secretion of some extracellular matrix (ECM) proteins, such as type III procollagen (PC III), type IV collagen (collagen IV), laminin (LN), hyaluronic acid (HA), were all decreased in supernatant of GbE treated HSC cells. CONCLUSIONS: Our results suggest that GbE confers its anti-fibrosis effects through inhibiting HSC proliferation, reducing TGF-beta1 and CTGF expression and consequently suppressing the collagen production and ECM secretion.     

Effects of gliclazide on low-density lipoprotein oxidizability and atherosclerosis in cholesterol-fed rabbits.

We studied the effects of a widely-used sulfonylurea, gliclazide, on the oxidizability of low density lipoprotein (LDL) and the development of experimental atherosclerosis in cholesterol-fed rabbits. Daily oral administration of gliclazide (20 mg/kg/day) tended to inhibit the aortic atherosclerosis induced by feeding a 1% cholesterol diet for 10 weeks, although it did not affect diet-induced hyperlipidemia. The administration of gliclazide tended to inhibit the increase of serum thiobarbituric acid-reacting substances (TBARS) by cholesterol feeding and to increase the lag time of the conjugated-diene formation of LDL subjected to in vitro oxidation by copper ion, although without significance. The present study suggests that gliclazide may have antioxidative properties in vivo, and have further beneficial effects for the treatment of diabetes mellitus by inhibiting the oxidation of LDL.     

Protective effects of Ginkgo biloba extract on the ethanol-induced gastric ulcer in rats

AIM: To evaluate the preventive effect of Ginkgo biloba extract (GbE) on ethanol-induced gastric mucosal injuries in rats. METHODS: Female Wistar albino rats were used for the studies. We randomly divided the rats for each study into five subgroups: normal control, experimental control, and three experimental groups. The gastric ulcers were induced by instilling 1 mL 50% ethanol into the stomach. We gave GbE 8.75,17.5,26.25 mg/kg intravenously to the experimental groups respectively 30 min prior to the ulcerative challenge. We removed the stomachs 45 min later. The gastric ulcers, gastric mucus and the content of non-protein sulfhydryl groups (NP-SH), malondialdehyde (MDA), c-Jun kinase (JNK) activity in gastric mucosa were evaluated. The amount of gastric juice and its acidity were also measured. RESULTS: The findings of our study are as follows: (1) GbE pretreatment was found to provide a dose-dependent protection against the ethanol-induced gastric ulcers in rats; (2) the GbE pretreatment afforded a dose-dependent inhibition of ethanol-induced depletion of stomach wall mucus, NP-SH contents and increase in the lipid peroxidation (increase MDA) in gastric tissue; (3) gastric ulcer induced by ethanol produced an increase in JNK activity in gastric mucosa which also significantly inhibited by pretreatment with GbE; and (4) GbE alone had no inhibitory effect on gastric secretion in pylorus-ligated rats. CONCLUSION: The finding of this study showed that GbE significantly inhibited the ethanol-induced gastric lesions in rats. We suggest that the preventive effect of GbE may be mediated through: (1) inhibition of lipid peroxidation; (2) preservation of gastric mucus and NP-SH; and (3) blockade of cell apoptosis.     

Ginkgo biloba extract alleviates liver fibrosis induced by CCl in rats.

AIMS: To investigate the protective effect of Ginkgo biloba extract (GbE) on liver fibrosis induced by carbon tetrachloride (CCl4) in rats and expressions of transforming growth factor beta1 (TGF-beta1) and collagen I during this period. METHODS: The effect of GbE on liver fibrogenesis was detected by hematoxylin and eosin staining (H&E staining), Masson's trichrome staining, and electron microscope study. Blood samples were collected for measurement of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin. Malondialdehyde (MDA) in liver tissue was detected by the thiobarbituric acid (TBA) method. Immunohistochemistry assay and RT-PCR were used to examine the protein expressions and mRNA levels of TGF-beta1 and collagen I, respectively. RESULTS: H&E, Masson's trichrome stainings and electron microscope study showed liver fibrosis in rats was greatly alleviated when treated with GbE. Additionally, there was a remarkable improvement of serum ALT, AST, albumin and MDA in the GbE-treated group. Immunohistochemistry and RT-PCR results showed GbE intervention significantly inhibited TGF-beta1 and collagen I expressions in rat liver. No side effects of GbE were found during these experiments. But GbE could not reverse the pathological changes of liver fibrosis completely when compared with normal control. CONCLUSION: GbE can partially protect rat liver from the fibrogenesis induced by CCl4. The mechanism may lie in its effect of inhibiting oxidative stress caused by liver injury and expressions of signal molecules such as TGF-beta1. GbE may thus be of potential help as a medicament or food additive for alleviation of liver fibrogenesis.     

Circulating desialylated low density lipoprotein

Accumulation of lipids is the central event in the development of atherosclerotic lesion. Circulating low-density lipoprotein (LDL) particles are known to be the major source of cholesterol and other lipids stored in atherosclerotic plaque. However, not all LDL particles possess atherogenic properties. In order to induce lipid accumulation in arterial cells, LDL particles have to undergo modifications. Although among such modifications the oxidation remains the most studied one, other atherogenic LDL modifications have been described. According to a series of studies conducted with blood serum and LDL from atherosclerotic patients, desialylation is one of the earliest if not the first atherogenic modification of LDL. Desialylation occurs in the bloodstream and is followed by a cascade of other modifications, including the reduction of LDL particle size and increase of its density, acquisition of negative electrical charge, oxidation and formation of highly atherogenic complexes. In this mini-review we will discuss the concept of multiple atherogenic modification of LDL leading to initiation and progression of atherosclerosis.     

Anti-oxidative properties of fluvastatin, an HMG-CoA reductase inhibitor, contribute to prevention of atherosclerosis in cholesterol-fed rabbits

Studies in vitro reveal that fluvastatin, an HMG-CoA reductase inhibitor, has a strong DPPH radical scavenging activity and achieves concentration-dependent inhibition of copper- and cell-induced oxidation of low-density lipoprotein (LDL). To further examine the anti-oxidative activity of fluvastatin in vivo, we elucidated the effects of chronic treatment with fluvastatin at a dose insufficient to reduce plasma cholesterol levels (2 mg/kg per day) on vasomotion and vascular oxidative stress in thoracic aortas of 0.5% cholesterol-fed rabbits. After 12 weeks of dietary treatment, aortic segments from rabbits fed cholesterol alone showed impaired endothelium-dependent relaxation responses to acetylcholine and A23187 compared to normal chow-fed rabbits in association with a significant increase in plasma total cholesterol levels. In contrast, although plasma total cholesterol levels were not different from those in control cholesterol-fed rabbits, aortic segments from fluvastatin-treated rabbits showed normal relaxation. Compared with rabbits fed cholesterol alone, fluvastatin treatment decreased susceptibility of LDL to ex vivo copper-induced oxidation, reduced vascular superoxide generation, and atheromatous plaque formation. In conclusion, the potent anti-oxidative properties of fluvastatin in addition to its cholesterol-lowering activity appear to contribute to its anti-atherosclerotic effect in vivo.     

In vivo and in vitro evidence for the glycoxidation of low density lipoprotein in human atherosclerotic plaques

Although there have been suggestions that the glycation and oxidation of low density lipoprotein (LDL) might increase its atherogenic potential, little is known about the presence of glycoxidative LDL in human atherosclerotic lesions. We developed specific antibodies against different immunological epitopes of AGE structures, including N(epsilon)-(carboxymethyl)lysine-protein adduct (CML), a glycoxidation product, and structure(s) other than CML (nonCML), and a monoclonal antibody against oxidized phosphatidylcholine (oxPC), as an epitope of oxidized LDL. Immunohistochemical analysis demonstrated that the CML- and oxPC-epitopes were accumulated mainly in macrophage-derived foam cells in atherosclerotic lesions, including fatty streaks and atherosclerotic plaques. On the other hand, the nonCML-epitope and apolipoprotein B were localized mainly in extracellular matrices of atherosclerotic lesions. The CML- and oxPC-epitopes were characterized by a model antigen-generating system using the copper ion-induced peroxidation and/or glucose-induced glycation of LDL. The glycoxidation of LDL caused the formation of CML-epitope with increasing concentrations of copper ion and glucose. It was also formed to some extent in LDL incubated with high concentrations (500 mM) of glucose. However, no CML-epitope was observed in oxidized LDL induced by copper ion alone. On the other hand, the formation of oxPC-epitope in LDL was dependent on copper ion-induced peroxidation, but independent of glucose-induced glycation. The addition of chelators, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, reduced the increase in electrophoretic mobility and TBARS caused by the peroxidation and glycoxidation of LDL, but had no effects on the formation of fructosamine caused by the glycation and glycoxidation of LDL. Chelators as well as aminoguanidine protected the formation of CML-epitope in glycated or glycoxidative LDL. Although the formation of oxPC-epitope was completely inhibited by the addition of chelators, it was partially protected by aminoguanidine. These in vitro results suggest that the glycoxidative modification of LDL may occur in the arterial intima, and may contribute to the development of human atherosclerotic lesions.