叶酸降低高同型半胱氨酸血症大鼠主动脉单核细胞趋化蛋白-1的表达

目的： 探讨补充叶酸对高蛋氨酸(Met)喂养所致的高同型半胱氨酸（Hcy）血症大鼠主动脉单核细胞趋化蛋白（MCP-1）表达的影响。方法: SD大鼠30只随机分3组:即正常对照组(control)、高蛋氨酸组(Met)、蛋氨酸＋叶酸组(Met＋folate)，每组10只，分别给予普通饲料、普通饲料加1.7%蛋氨酸、普通饲料加1.7%蛋氨酸和0.006%的叶酸，饲养45 d，测定血浆总同型半胱氨酸浓度(thcy)，用免疫组织化学染色法及蛋白免疫印迹（Western blotting）法检测大鼠的主动脉单核细胞趋化蛋白MCP-1表达。结果: 高Met组血浆总同型半胱氨酸浓度明显高于control组(P<0.01)，Met＋folate组血浆总同型半胱氨酸浓度明显低于Hhcy组(P<0.01)； 高Met组大鼠主动脉表达的MCP-1明显多于control组(46.41±4.23 vs 15.73±2.74； P<0.05)，而Met＋folate组能抑制高同型半胱氨酸血症所致的主动脉MCP-1的表达(23.12±4.40 vs 46.41±4.23; P<0.05)。结论: 大鼠喂以高Met饲料45 d，可充分诱导高Hcy血症。而叶酸补充治疗，在显著降低血浆tHcy水平的同时，也降低了高同型半胱氨酸大鼠主动脉单核细胞趋化蛋白MCP-1的表达。     

Effect of incremental doses of folate on homocysteine and metabolically related vitamin concentrations in nondiabetic patients on peritoneal dialysis

The role of folate supplementation in reducing hyperhomocystinemia in patients on dialysis has been reported, but the optimal dose of folate is still unknown. The aim of the present study was to investigate whether greater than 5 mg/day folate supplementation provides any additional effect on plasma homocysteine (HCY) levels. The study was prospective, open, and had no control group. Of the 64 eligible nondiabetic patients on peritoneal dialysis with hyperhomocystinemia (>20 micromol/L), 56 were given oral folate (5 mg/day) for 3 months. When Hcy did not fall below 20 micromol/L, folate doses were increased by 5 mg every 3 months to up to 15 mg/day. With 5 mg/day supplementation, serum folate concentrations increased above the upper confidence limit in 23 patients and erythrocyte folate concentrations in 27 patients. Hcy levels decreased to less than 15 micromol/L in 6 cases and by more than 50% in 12 cases. Nineteen of the remaining patients were given 10 mg/day folate. After increasing the dose, serum and erythrocyte folate levels rose above the upper detection limit. In one patient, plasma Hcy concentrations decreased to less than 15 micromol/L. Ten patients were given 15 mg/day oral folate for an additional 3 months with no effect on homocystinemia. This study confirms that oral folate supplementation may improve hyperhomocystinemia even in patients on dialysis with normal serum or erythrocyte folate concentrations. In fact, serum and erythrocyte levels cannot predict the effect of supplementation on plasma Hcy levels. However, 5 mg/day folate supplementation normalized Hcy in 10% of cases and reduced Hcy levels in another 21%. Increasing the folate dose to greater than 5 mg/day had a minimal (10 mg/day) or no (15 mg/day) additional effect on Hcy concentrations. Despite the minimal effect of increasing folate doses, given the low cost, the absence of side effects, and the high cardiovascular risk for patients on peritoneal dialysis, a careful attempt to increase the dose of oral folate up to 10 mg/day might be suggested.     

卡维地洛对高血压大鼠主动脉的保护作用

目的 :研究卡维地洛对核因子 κB(NF κB)、单核细胞趋化蛋白 1(MCP 1)在自发性高血压大鼠 (SHR)大血管中表达的影响 ,探讨其对血管保护的机制。方法 :18只雄性 12周龄SHR随机分为阳性组 ,卡维地洛组 ( 30mg/kg·d) ,美托洛尔组 ( 50mg/kg·d) ,灌喂 8周 ;另选同龄雄性WistarKyoto大鼠为阴性组 (n =6 )。用免疫组化法测各组主动脉NF κB、MCP 1的表达 ,ELISA法测血清MCP 1含量。结果 :与阴性组比较 ,阳性组主动脉组织中NF κB、MCP 1表达增加 (P<0 .0 1) ,且两者正相关 (r=0 .72 8,P <0 .0 1) ;血清MCP 1含量升高 1.6 4(P <0 .0 1)。 8周后 ,治疗组之间血压无明显差异 (P >0 .0 5) ,但卡维地洛更显著抑制NF -κB、MCP 1表达 (P <0 .0 5)。结论 :卡维地洛可能独立于降压外抑制NF κB的活化来调控MCP 1表达。     

N-homocysteinylation of tau and MAP1 is increased in autopsy specimens of Alzheimer's disease and vascular dementia

The pathomechanisms that associate a deficit in folate and/or vitamin B12 and the subsequent hyperhomocysteinemia with pathological brain ageing are unclear. We investigated the homocysteinylation of microtubule-associated proteins (MAPs) in brains of patients with Alzheimer's disease or vascular dementia, and in rats depleted in folate and vitamin B12, Cd320 KO mice with selective B12 brain deficiency and H19-7 neuroprogenitors lacking folate. Compared with controls, N-homocysteinylated tau and MAP1 were increased and accumulated in protein aggregates and tangles in the cortex, hippocampus and cerebellum of patients and animals. N-homocysteinylation dissociated tau and MAPs from β-tubulin, and MS analysis showed that it targets lysine residues critical for their binding to β-tubulin. N-homocysteinylation increased in rats exposed to vitamin B12 and folate deficit during gestation and lactation and remained significantly higher when they became 450 days-old, despite returning to normal diet at weaning, compared with controls. It was correlated with plasma homocysteine (Hcy) and brain expression of methionine tRNAsynthetase (MARS), the enzyme required for the synthesis of Hcy–thiolactone, the substrate of N-homocysteinylation. Experimental inactivation of MARS prevented the N-homocysteinylation of tau and MAP1, and the dissociation of tau and MAP1 from β-tubulin and PSD95 in cultured neuroprogenitors. In conclusion, increased N-homocysteinylation of tau and MAP1 is a mechanism of brain ageing that depends on Hcy concentration and expression of MARS enzyme. Its irreversibility and cumulative occurrence throughout life may explain why B12 and folate supplementation of the elderly has limited effects, if any, to prevent pathological brain ageing and cognitive decline. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

精神分裂症大鼠血浆H2S、Hcy、叶酸及VitB6水平及其相关性分析

目的探讨精神分裂症大鼠血浆硫化氢(H2S)、同型半胱氨酸(Hcy)、叶酸和维生素(Vit)B6水平的变化及其相关性。方法检测精神分裂症大鼠和正常对照组的血浆H2S、Hcy、叶酸及VitB6水平。精神分裂症大鼠血浆H2S水平与Hcy、叶酸和VitB6水平的相关性用直线相关分析。结果与正常对照组比较,精神分裂症组血浆Hcy水平显著增高,血浆H2S、叶酸、Vit B6水平显著降低(P<0.05~0.001)。精神分裂症组血浆H2S水平与Hcy水平呈负相关(r=-0.7214,P<0.001),与血浆叶酸及VitB6水平呈正相关(r=0.5189,P<0.001;r=0.4299,P<0.05)。结论精神分裂症组血浆H2S、叶酸和VitB6明显降低,Hcy水平升高。H2S水平降低可能参与了高同型半胱氨酸血症致精神分裂症的发病机制。     

螺旋藻对大鼠高同型半胱氨酸血症的影响

目的：研究螺旋藻(SP)对大鼠高同型半胱氨酸血症(hyper homocysteinemia,HHcy)的影响。方法：用高蛋氨酸饮食复制HHcy大鼠模型,给予叶酸或SP干预12周。以高压液相色谱法测定血浆Hcy浓度,硫代巴比妥酸反应比色法测定血浆丙二醛(MDA)浓度,黄嘌呤氧化酶法测定血浆超氧化物歧化酶(SOD),并采用链霉亲和素-过氧化物酶(S-P)免疫组化染色法检测动脉平滑肌增殖细胞核抗原(proliferating cell nuclear antigen,PC- NA)的表达。结果：HHcy模型组血浆Hcy浓度、MDA水平、SOD活力及平滑肌PCNA阳性细胞率明显高于正常对照组,经叶酸及SP干预后,上述指标都比模型组降低。结论：螺旋藻在体内可减低血浆Hcy和MDA浓度,有效消除氧化自由基,降低动脉平滑肌增殖指数,保护HHcy血症损伤的内皮细胞。     

缬沙坦对动脉粥样硬化兔核因子κB和单核细胞趋化因子-1的影响

目的:探讨血管紧张素Ⅱ1型受体(AT1R)拮抗剂缬沙坦(Val-sartan)对动脉粥样硬化(AS)兔核因子κB(NF-κB)和单核细胞趋化因子-1(MCP-1)的影响。方法:24只雄性日本大耳白兔随机分为3组:正常对照组,AS模型组,缬沙坦治疗组。喂养12周,进行血脂测定、主动脉内膜/中膜比值测定、主动脉NF-κB和MCP-1的表达和蛋白质含量测定。结果:AS模型组NF-κB和MCP-1蛋白含量显著增加(P<0.05),缬沙坦治疗组显著减少(P<0.05),且NF-κB活化和MCP-1表达之间成正相关(r=0.728,P<0.01);缬沙坦治疗组及AS模型组的血清胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)均无差别(P均>0.05),但均高于正常对照组。与AS模型组比较,缬沙坦治疗组主动脉内膜/中膜厚度比值明显减少(P<0.05)。结论:缬沙坦可以干预AS的形成,其机制可能与其抑制NF-κB的活化从而下调MCP-1的表达有关。     

丹酚酸B对糖尿病大鼠血管舒张功能、NF-κB活化及炎症因子表达的影响

目的:研究丹酚酸B对糖尿病大鼠血管舒张功能的改善作用及其可能机制。方法:SD大鼠40只,采用高糖高脂饮食联合腹腔注射链脲佐菌素方法建立糖尿病大鼠模型(随机血糖16.7 mmol/L)。将糖尿病大鼠随机分为模型组、Sal B高剂量(160 mg·kg~(-1)·d~(-1))组和Sal B低剂量(80 mg·kg-1·d-1)组,另取10只正常大鼠作为对照组。丹酚酸B组每日灌胃给予相应剂量丹酚酸B,共6周。采用离体动脉环实验检测血管舒张功能,HE染色观察大鼠主动脉病理学变化,ELISA法测定血清白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)及C反应蛋白(CRP)水平,比色法测定血管组织中总抗氧化能力、丙二醛(MDA)和一氧化氮(NO)水平,Western blot法检测主动脉细胞间黏附分子1(ICAM-1)和单核细胞趋化因子1(MCP-1)的蛋白表达水平以及核因子κB(NF-κB)的活化水平。结果:丹酚酸B明显减轻糖尿病大鼠主动脉病变,改善血管舒张功能,提高血管组织总抗氧化能力和NO水平,降低组织MDA以及血清IL-6、TNF-α和CRP水平(P0.05或P0.01),并减少主动脉NF-κB p65亚基核转位及ICAM-1和MCP-1蛋白表达水平(P0.05或P0.01)。结论:丹酚酸B可明显改善糖尿病大鼠血管舒张功能,其机制可能与改善机体氧化应激状态、抑制NF-κB活化而减轻血管炎性病变有关。     

1型多聚ADP核糖聚合酶抑制剂对高同型半胱氨酸血症大鼠内皮功能的保护作用

目的：探讨1型多聚ADP 核糖聚合酶（PARP1）抑制剂3-氨基苯甲酰胺 （3-AB）对高同型半胱氨酸血症（Hhcy）大鼠内皮功能的保护作用。方法：SD大鼠30只随机分为3组：模型组、3-AB组和正常对照组，每组10只，分别给予普通饲料加1.7%蛋氨酸、普通饲料加1.7%蛋氨酸同时每天腹腔注射3-AB 20 mg·kg-1和普通饲料，饲养45 d。观察主动脉组织形态结构的改变；测定血浆同型半胱氨酸（Hcy）、内皮素-1（ET-1）和一氧化氮（NO）的水平；检测大鼠胸主动脉环对乙酰胆碱(Ach)与硝普钠(SNP)的反应；检测大鼠胸主动脉PARP1蛋白的表达。结果：大鼠喂以高蛋氨酸饲料45 d可诱导Hhcy。与模型组相比3-AB组大鼠NO水平明显升高而ET-1水平明显降低（P<0.01）。病理形态学观察模型组主动脉内膜病变明显，3-AB组病变程度减轻。与正常对照组比较，模型组胸主动脉对Ach引起的最大的内皮依赖性舒张反应（EDR）明显减弱（0.26±0.03 vs 0.89±0.11，P<0.01）；而3-AB组EDR反应较模型组显著改善（0.57±0.12 vs 0.26±0.03，P<0.01）。模型组较正常对照组大鼠主动脉PARP表达明显升高（P<0.05），3-AB组PARP表达较模型组明显降低（P<0.05）。结论： PARP抑制剂3-AB有效地改善高同型半胱氨酸血症大鼠血管内皮功能，并在一定程度上改善血管早期病理形态学的改变。     

过氧化物酶体增殖物激活受体δ对同型半胱氨酸诱导人脐静脉内皮细胞MCP-1 mRNA表达的影响及机制

目的: 观察过氧化物酶体增殖物激活受体δ(PPARδ)激活后对同型半胱氨酸(Hcy)诱导的人脐静脉内皮细胞(HUVECs)单核细胞趋化蛋白-1(MCP-1)mRNA表达的影响及机制。方法: 胶原酶消化法获取和体外培养HUVECs;实验分组:空白对照组、Hcy组、GW0742(PPARδ特异激动剂)组和二亚苯基碘鎓(DPI,NADPH氧化酶特异抑制剂)组,RT-PCR检测MCP-1和PPARδ mRNA表达,Western blotting测PPARδ蛋白水平,2',7’-二氯荧光素二乙酸酯(DCFH-DA)染色测定细胞内活性氧(ROS)。结果: 与空白对照组相比,Hcy呈浓度依赖性 促进人血管内皮细胞MCP-1 mRNA的表达,抑制细胞PPARδ mRNA表达,当Hcy浓度为10^-5 mol/L时,MCP-1 mRNA表达显著增加,PPARδ mRNA明显降低(P<0.01);与Hcy组相比,GW0742组细胞MCP-1 mRNA的表达下降(P<0.01);与空白对照组相比,Hcy组细胞内ROS明显增强;GW0742显著抑制Hcy诱导的细胞内ROS水平。结论: PPARδ激活可抑制Hcy诱导人血管内皮细胞MCP-1 mRNA的表达,其机制可能与抑制ROS信号通路有关。     

植物甾醇酯对大鼠主动脉衰老及相关基因表达的影响

目的:探讨植物甾醇酯延缓大鼠主动脉衰老的作用及其机制。方法:将42只12月龄雌性SD大鼠随机均分为对照组、模型组和植物甾醇酯干预组,分别喂食基础饲料、高脂饲料和高脂加2%植物甾醇酯(W/W)饲料6个月。采用HE染色法和Masson染色法对主动脉横截面石蜡切片进行染色,观察主动脉组织的病理学改变,对血管壁平滑肌细胞和胶原纤维的绝对面积进行图像分析。检测血浆脂质蛋白、晚期糖基化终末产物(AGEs)、丙二醛(MDA)的含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活性。分别采用real-time PCR和Western blot的方法评估主动脉组织沉默信息调节因子1(SIRT1)和过氧化物酶体增殖物激活受体γ(PPARγ)的mRNA和蛋白表达水平。结果:与模型组相比,植物甾醇酯干预组的血浆总胆固醇和低密度脂蛋白胆固醇水平显著降低,高密度脂蛋白胆固醇的水平相反(P0.05),甘油三酯的水平没有统计学差异;主动脉内膜和中膜的增厚以及平滑肌细胞的迁移均得到改善;主动脉平滑肌细胞和胶原纤维的含量显著下降(P0.05);血浆AGEs的含量显著降低(P0.05);机体的抗氧化功能有所提升,血浆MDA的含量显著减少(P0.05),SOD和CAT活性的差异没有统计学意义;PPARγ的表达下调,SIRT1的表达上调(P0.05)。结论:植物甾醇酯能够延缓大鼠主动脉的衰老。其机制可能与降低机体活性氧的生成有关。植物甾醇酯可能通过激活SIRT1或抑制PPARγ的表达而发挥作用。     

高甲硫氨酸诱发高同型半胱氨酸血症对抗凝血酶-Ⅲ,蛋白C和血管性血友病因子的影响

目的：观察高甲硫氨酸喂饲动物诱发高同型半胱氨酸血症对凝血和抗凝作用的影响。方法：新西兰白兔随机分为甲硫氨酸组和对照组各9只,16周末检测凝血和抗凝及有关生化指标,同时行主动脉血管性血友病因子免疫组化检查。结果：甲硫氨酸组的血清甲硫氨酸和同型半胱氨酸均显著高于对照组,分别为(49.97±5.34) μmol/L、(14.78±1.97) μmol/L和(13.30±2.19) μmol/L比(5.36±1.19) μmol/L（P<0.01）;血浆抗凝血酶-Ⅲ浓度（AT-Ⅲ:Ag）和活性（AT-Ⅲ:A）、蛋白C（PC）浓度均显著低于对照组（P<0.01）;血管性血友病因子（vWF）显著高于对照组（P<0.01）。血管内皮细胞vWF表达显著低于对照组（P<0.01）。结论：高甲硫氨酸诱发高同型半胱氨酸血症具有促进凝血和抑制抗凝的作用。     

Creatine supplementation reduces increased homocysteine concentration induced by acute exercise in rats

The aim of this study was to evaluate the effect of creatine supplementation on homocysteine (Hcy) metabolism after acute aerobic and anaerobic exercise. A total of 112 Wistar rats were divided into four groups: aerobic exercise (A), aerobic exercise plus creatine supplementation (ACr), anaerobic exercise (An), and anaerobic exercise plus creatine-supplemented (AnCr). Creatine supplementation consisted of the addition of 2% creatine monohydrate to the diet. After 28 days, the rats performed an acute moderate aerobic exercise bout (1 h swimming with 4% of total body weight load) or an acute intense anaerobic exercise bout (6 × 30-s vertical jumps into the water with a 30-s rest between jumps, with 50% of total body weight load). The animals were killed before (pre) and at 0, 2, and 6 h (n = 8) after acute exercise. Plasma Hcy concentration increased significantly (P < 0.05) up to 2 h after anaerobic exercise (An group: pre 8.7 ± 1.2, 0 h 13.2 ± 2.3, 2 h 13.5 ± 4.2, and 6 h 12.1 ± 2.2, μmol/l). The same did not occur in acute aerobic exercised animals. Nevertheless, creatine supplementation significant decreased (P < 0.05) homocysteine concentration independent of exercise intensity (AnCr group: pre 17%, 0 h 80%, 2 h 107%, and 6 h 48%; ACr group: pre 17%, 0 h 19%, 2 h 28%, and 6 h 27%). Increased S-adenosylhomocysteine was also found in the An group. In conclusion, acute intense anaerobic exercise increased plasma Hcy concentration. On the other hand, creatine supplementation decreased plasma Hcy independent of exercise intensity.     

同型半胱氨酸介导的内质网应激对肝细胞脂质代谢的影响

目的： 探讨同型半胱氨酸（Hcy）介导的内质网应激对肝细胞脂质代谢的影响。方法: 5 mmol/L Hcy与HepG2细胞共孵育，检测细胞内Hcy、甘油三酯、胆固醇的含量。高蛋氨酸饮食诱导小鼠高Hcy血症，分析肝细胞内甘油三酯(TGE)、胆固醇(CHO)含量的变化，检测内质网应激蛋白葡萄糖调节蛋白78（GRP-78）、胆固醇调节元件结合蛋白（SREBP-1） mRNA及蛋白表达的变化。结果: 与Hcy孵育后，各时点HepG2细胞内Hcy、脂质（TGE、CHO）含量均显著升高（P<0.05,vs 0 h）。高蛋氨酸饮食小鼠各时点血浆Hcy、肝细胞内TGE、CHO含量均显著高于0周（P<0.05），而血浆TGE、CHO含量升高并不明显（P>0.05,vs 0周）；肝组织内质网应激蛋白GRP-78、SREBP-1 mRNA及其蛋白表达均显著高于0周（P<0.05）。结论: Hcy诱导的内质网应激可致内源性胆固醇调节通路失调，并使肝细胞合成、摄取甘油三酯、胆固醇增加。     

Experimental evidence of oxidative stress in plasma of homocystinuric patients: a possible role for homocysteine

Homocystinuria is an inherited disorder biochemically characterized by high urinary excretion of homocystine and increased levels of homocysteine (Hcy) and methionine in biological fluids. Affected patients usually have a variety of clinical and pathologic manifestations. Previous experimental data have shown a relationship between Hcy and oxidative stress, although very little was reported on this process in patients with homocystinuria. Therefore, in the present study we evaluated parameters of oxidative stress, namely carbonyl formation, malondialdehyde (MDA) levels, sulfhydryl content and total antioxidant status (TAS) in patients with homocystinuria at diagnosis and under treatment with a protein restricted diet supplemented by pyridoxine, folate, betaine, and vitamin B(12). We also correlated plasma Hcy and methionine concentrations with the oxidative stress parameters examined. We found a significant increase of MDA levels and carbonyl formation, as well as a reduction of sulfhydryl groups and TAS in plasma of homocystinuric patients at diagnosis relatively to healthy individuals (controls). We also verified that Hcy levels were negatively correlated with sulfhydryl content and positively with MDA levels. Furthermore, patients under treatment presented a significant reduction of the content of MDA, Hcy and methionine concentrations relatively to patients at diagnosis. Taken together, the present data indicate that lipid and protein oxidative damages are increased and the antioxidant defenses diminished in plasma of homocystinuric patients, probably due to increased reactive species elicited by Hcy. It is therefore presumed that oxidative stress participates at least in part in the pathogenesis of homocystinuria.     

Elevated homocysteine levels in human immunodeficiency virus-infected patients under antiretroviral therapy: A meta-analysis

AIM: To evaluate the association between the levels of homocysteine (Hcy), folate, vitamin B12 in human immunodeficiency virus (HIV)-infected patients who were treated with antiretroviral therapy (ART) or not treated with ART.METHODS: The PubMed and Scielo databases were searched. Eligible studies regarding plasma Hcy level in HIV-infected patients were firstly identified. After careful analysis by two independent researches, the identified articles were included in the review according to two outcomes (1) Hcy, folate and vitamin B12 blood concentration in HIV-infected subjects vs health controls and; (2) Hcy blood concentration in HIV-infected subjects under ART vs not treated with ART. RevMan (version 5.2) was employed for data synthesis.RESULTS: A total of 12 studies were included in outcome 1 (1649 participants, 932 cases and 717 controls). Outcome 1 meta-analysis demonstrated higher plasma Hcy (2.05 µmol/L; 95%CI: 0.10 to 4.00, P < 0.01) and decreased plasma folate concentrations (-2.74 ng/mL; 95%CI: -5.18 to -0.29, P < 0.01) in HIV-infected patients compared to healthy controls. No changes in vitamin B12 plasma concentration were observed between groups. All studies included in the outcome 2 meta-analysis (1167 participants; 404 HIV-infected exposed to ART and 757 HIV-infected non-ART patients) demonstrated higher mean Hcy concentration in subjects HIV-infected under ART compared to non-ART HIV subjects (4.13 µmol/L; 95%CI: 1.34 to 6.92, P < 0.01).CONCLUSION: This meta-analysis demonstrated that the levels of Hcy and folate, but not vitamin B12, were associated with HIV infection. In addition, Hcy levels were higher in HIV-infected patients who were under ART compared to HIV-infected patients who were not exposed to ART. Our results suggest that hyperhomocysteinemia should be included among the several important metabolic disturbances that are associated with ART in patients with HIV infection.     

Vitamin E attenuates homocysteine and cholesterol induced damage in rat aorta

BackgroundThe aim of this study was to investigate the effect of vitamin E on homocysteine and cholesterol-induced damage of rat aorta.MethodsWistar rats (all fed with a vitamin E poor diet) were divided into five groups. Control group was fed with the diet only, the second group received 1 mg kg^?1 day^?1 l-methionine in drinking water, the third group was fed with 2% cholesterol containing diet, the fourth group received l-methionine and cholesterol together, and the fifth group was fed with l-methionine and cholesterol and received intramuscular injections of vitamin E. After 4 weeks serum homocysteine, cholesterol and vitamin E levels were measured; aortas were removed; collagen and elastin and the major extracellular matrix components were evaluated microscopically as indicators of aortic degeneration. Aortic collagen content was measured by a colorimetric hydroxyproline assay.ResultsFour-week diet supplementation with methionine and cholesterol caused a twofold increase in serum homocysteine and 22% increase in serum cholesterol levels; endothelial damage and degenerative alterations in the aortic media were observed, as indicated by the dissociation of elastic fibers and accumulation of collagen. Vitamin E completely prevented the accumulation of collagen and largely prevented aorta damage as shown by the morphological data.ConclusionThe results indicate that, even moderate increases in homocysteine and cholesterol levels are sufficient to induce vascular degeneration that may be prevented by vitamin E supplementation.     

MTHFR Gene polymorphisms, B-vitamins and hyperhomocystinemia in young and middle-aged acute myocardial infarction patients

We have examined the prevalence of the C677T and A1298C single nucleotide polymorphisms (SNPs) in the methylenetetrahydrofolate reductase (MTHFR) gene in healthy Tamilians and in patients with acute myocardial infarction and related this polymorphism to plasma homocysteine concentrations, serum folate, serum cobalamin and riboflavin status. The SNPs in the MTHFR gene were determined by polymerase chain reaction-restriction fragment length polymorphism analysis. Plasma homocysteine, serum folate and serum cobalamin concentrations were analyzed using an automated chemiluminescence method and riboflavin status was assessed by measuring the erythrocyte glutathione reductase activity using spectrophotometric method. Out of the 200 young and middle-aged (<48 years) individuals included in the study, 100 were acute myocardial infarction (AMI) patients and 100 were healthy individuals with no documented history of heart diseases. There was a significant increase in homocysteine levels among the AMI patients as compared to the healthy controls (p<0.001). The results of this study indicate that hyperhomocystinemia is more prevalent in Tamilian AMI patients and that the MTHFR C677T and A1298C SNPs are not associated with hyperhomocystinemia. Folate status was found to be within normal range in all the study subjects. There was no correlation between homocysteine and different biochemical variables including cobalamin, folate and riboflavin. However, serum cobalamin was found to be significantly decreased in AMI patients when compared to controls (p<0.001). The simultaneous presence of decreased serum cobalamin status, hyperhomocystinemia and mutant genotype for both the SNPs might lead to an increased risk for the occurrence of AMI. Further intervention trials including the supplementation of cobalamin may prove whether homocysteine level decrease in response to the supplementation of cobalamin in individuals with hyperhomocystinemia and mutant genotype for both the above mentioned SNPs.     

饮食因素对大鼠脂肪细胞葡萄糖转运蛋白4的影响

目的:研究饮食因素对大鼠脂肪细胞葡萄糖转运蛋白4(GLUT4)的影响。方法:实验大鼠随机分为正常组(n=10)、模型组(n=10)和饮食干预组(n=10)。正常组以基础饲料喂养10周;模型组以高糖高脂饲料喂养10周;饮食干预组以高糖高脂饲料喂养4周后,改喂基础饲料6周。Westernblot法检测各组大鼠脂肪细胞内、外膜GLUT4含量。结果:模型组大鼠脂肪细胞内、外膜GLUT4含量均低于正常组(P<0.05)。与模型组大鼠相比,饮食干预组大鼠脂肪细胞内膜GLUT4含量无显著差异,但细胞外膜GLUT4含量增加P<0.05)。结论:高糖高脂饮食可能通过降低脂肪细胞GLUT4含量及其转位使大鼠产生胰岛素抵抗。饮食干预可提高脂肪细胞GLUT4含量并改善其转位,增加葡萄糖的摄取,提高胰岛素敏感性。     

依普利酮对高盐诱导的高血压大鼠主动脉内皮型一氧化氮合酶表达及活性的影响

目的:探讨依普利酮对高盐诱导的高血压大鼠主动脉内皮型一氧化氮合酶(e NOS)的表达及活性的影响。方法:50~60 g 4周龄雄性Wistar大鼠随机分为3组:对照(control,C)组用普通饲料饲养16周,高盐饮食(high salt diet,HS)组及依普利酮(eplerenone,Epl)组用5%高盐饲料饲养16周,C组和HS组于末4周给予同等剂量生理盐水灌胃,而Epl组于末4周给予依普利酮40 mg·kg-1·d-1灌胃。每2周检测各组大鼠尾动脉收缩压,16周后处死大鼠,留取主动脉。ELISA法检测醛固酮含量,蛋白免疫印迹法检测盐皮质激素受体(MR)及e NOS蛋白表达水平,化学比色法测定一氧化氮合酶活性,免疫组化染色法观察主动脉e NOS、神经型一氧化氮合酶(n NOS)及MR蛋白表达与定位。结果:(1)高盐饲料饲养8周后,大鼠收缩压即明显升高,并逐渐上升,16周时HS组收缩压较同时点C组明显升高(P0.05);依普利酮灌胃4周后,收缩压比灌胃前明显下降(P0.05)。(2)与C组比较,HS组、Epl组主动脉醛固酮含量明显增加(P0.05),且MR表达明显增加(P0.05)。(3)HS组较C组e NOS蛋白表达减少(P0.05)、结构型一氧化氮合酶(c NOS)活性也降低(P0.05);Epl组较HS组e NOS蛋白表达增加(P0.05)、c NOS活性增高(P0.05)。结论:(1)高盐诱导高血压大鼠的主动脉醛固酮含量明显增加,醛固酮可能通过激动MR降低主动脉e NOS蛋白表达及酶活性。(2)选择性MR拮抗剂依普利酮可恢复e NOS蛋白表达及活性,改善e NOS功能。