Obstructive jaundice leads to accumulation of oxidized low density lipoprotein in human liver tissue

Oxidized low density lipoprotein （ox-LDL） molecule is one of the most important modified lipoproteins produced during the oxidative stress. Modified lipoproteins have been defined as being part of the immune inflammatory mechanisms in association with oxidant stress. We have reported the accumulation of ox-LDL in Balb/c mice liver after bile duct ligation previously. Here, we investigated this finding in human beings with obstructive jaundice. Our study demonstrates that obstructive jaundice results in tremendous accumulation of ox-LDL in the liver tissue of patients.

Hepatitis C virus clearance and less liver damage in patients with high cholesterol, low-density lipoprotein cholesterol and APOE ε4 allele

BACKGROUND Cholesterol is related to improvements in the rate of sustained virological response and a robust immune response against the hepatitis C virus(HCV).APOE gene polymorphisms regulate cholesterol levels modifying the course of the HCV infection.The relationship between cholesterol,APOE alleles,and the outcome of HCV infection has not been evaluated in the admixed population of Mexico.AIM To investigate the role of APOE-ε2,-ε3,and-ε4 alleles and the metabolic profile in the outcome of HCV infection.METHODS A total of 299 treatment-na?ve HCV patients were included in this retrospective study.Patients were stratified in chronic hepatitis C(CHC)(n=206)and spontaneous clearance(SC)(n=93).A clinical record was registered.Biochemical tests were assessed by dry chemistry assay.APOE genotypes were determined using a Real-Time polymerase chain reaction assay.RESULTS Total cholesterol,low-density lipoprotein cholesterol(LDL-c),triglycerides,and hypercholesterolemia were higher in SC than CHC patients as well as the frequency of the APOEε4 allele(12.4%vs 7.3%).SC patients were overweight(54.8%).Theε4 allele was associated with SC(OR=0.55,95%CI:0.31-0.98,P=0.042)and mild fibrosis(F1-F2)in CHC patients(OR 0.091,95%CI 0.01-0.75,P=0.020).LDL-c≥101.5 mg/dL(OR=0.20,95%CI:0.10-0.41,P<0.001)and BMI≥26.6 kg/m2(OR=0.37,95%CI:0.18-0.76,P<0.001)were associated with SC status;while ALT≥50.5 IU/L was negatively associated(OR=5.67,95%CI:2.69-11.97,P<0.001).CONCLUSION In SC patients,the APOEε4 allele and LDL-c conferred a protective effect in the course of the HCV infection in the context of excess body weight.

Silymarin in non alcoholic fatty liver disease

AIM: This study was undertaken to evaluate the hepatic effects of silybum marianum on non alcoholic fatty liver disease (NAFLD). METHODS: In 72 patients affected by NAFLD, main metabolic, hepatic and anti-inflammatory parameters were assayed after 3 mo of a restricted diet and before silymarin treatment (twice a day orally). The brightness of liver echography texture (hepatorenal ratio brightness) was also defined at same time. These evaluations were repeated after 6 mo of treatment. RESULTS: Serum levels of some metabolic and anti-inflammatory data nonsignificantly lowered after 6 mo of silymarin. On the contrary, Steato test, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase were significantly (P < 0.001) reduced. Instead, the AST/ALT ratio unchanged. Finally, the hepatorenal brightness ratio, as an index of hepatic steatosis, significantly (P < 0.05) dropped. CONCLUSION: The obtained results indicate that silymarin appears to be effective to reduce the biochemical, inflammatory and ultrasonic indices of hepatic steatosis. Some parameters indicative of early stage of atherosclerosis were also lowered.

Lipoprotein metabolism in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease （NAFLD）, an pathologies characterized by fatty accumulation in escalating health problem worldwide, covers a spectrum of hepatocytes in early stages, with potential progression to liver inflammation, fibrosis, and failure. A close, yet poorly understood link exists between NAFLD and dyslipidemia, a constellation of abnormalities in plasma lipoproteins including triglyceride-rich very low density lipoproteins. Apolipoproteins are a group of primarily liver-derived proteins found in serum lipoproteins; they not only play an extracellular role in lipid transport between vital organs through circulation, but also play an important intracellu- lar role in hepatic lipoprotein assembly and secretion. The liver functions as the central hub for lipoprotein metab- olism, as it dictates lipoprotein production and to a significant extent modulates lipoprotein clearance. Lipoprotein metabolism is an integral component of hepatocellular lipid homeostasis and is implicated in the pathogenesis, potential diagnosis, and treatment of NAFLD.

Regulation and deregulation of cholesterol homeostasis: The liver as a metabolic "power station"

Cholesterol plays several structural and metabolic roles that are vital for human biology. It spreads along the entire plasma membrane of the cell, modulating fluidity and concentrating in specialized sphingolipid-rich domains called rafts and caveolae. Cholesterol is also a substrate for steroid hormones. However, too much cholesterol can lead to pathological pictures such as atherosclerosis, which is a consequence of the accumu- lation of cholesterol into the cells of the artery wall. The liver is considered to be the metabolic power station of mammalians, where cholesterol homeostasis relies on an intricate network of cellular processes whose deregulations can lead to several life-threatening pathologies, such as familial and age-related hypercholesterolemia. Cholesterol homeostasis maintenance is carried out by: biosynthesis, via 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity; uptake, through low density lipoprotein receptors (LDLr); lipoprotein release in the blood; storage by esterification; and degradation and conversion into bile acids. Both HMGR and LDLr are transcribed as a function of cellular sterol amount by a family of transcription factors called sterol regulatory element binding proteins that are responsible for the maintenance of cholesterol homeostasis through an intricate mechanism of regulation. Cholesterol obtained by hepatic de novo synthesis can be esterified and incorporated into apolipoprotein B-100-containing very low density lipoproteins, which are then secreted into the bloodstream for transport to peripheral tissues. Moreover, dietary cholesterol is transferred from the intestine to the liver by high density lipoproteins (HDLs); all HDL particles are internalized in the liver, interacting with the hepatic scavenger receptor (SR-B1). Here we provide an updated overview of liver cholesterol metabolism regulation and deregulation and the causes of cholesterol metabolism-related diseases. Moreover, current pharmacological treatment and novel hypocho-lesterolemic strategies will also be introduced.

Cholesterol metabolism in cholestatic liver disease and liver transplantation:From molecular mechanisms to clinical implications

The aim of this review is to enlighten the critical roles that the liver plays in cholesterol metabolism. Liver transplantation can serve as gene therapy or a source of gene transmission in certain conditions that affect cholesterol metabolism, such as low-density-lipoprotein(LDL) receptor gene mutations that are associated with familial hypercholesterolemia. On the other hand, cholestatic liver disease often alters cholesterol metabolism. Cholestasis can lead to formation of lipoprotein X(Lp-X), which is frequently mistaken for LDL on routine clinical tests. In contrast to LDL, Lp-X is non-atherogenic, and failure to differentiate between the two can interfere with cardiovascular risk assessment, potentially leading to prescription of futile lipid-lowering therapy. Statins do not effectively lower Lp-X levels, and cholestasis may lead to accumulation of toxic levels of statins. Moreover, severe cholestasis results in poor micellar formation, which reduces cholesterol absorption, potentially impairing the cholesterol-lowering effect of ezetimibe. Apolipoprotein B-100 measurement can help distinguish between atherogenic and non-atherogenic hypercholesterolemia. Furthermore, routine serum cholesterol measurements alone cannot reflect cholesterol absorption and synthesis. Measurements of serum non-cholesterol sterol biomarkers- such as cholesterol precursor sterols, plant sterols, and cholestanol- may help with the comprehensive assessment of cholesterol metabolism. An adequate cholesterol supply is essential for liver-regenerative capacity. Low preoperative and perioperative serum cholesterol levels seem to predict mortality in liver cirrhosis and after liver transplantation. Thus, accurate lipid profile evaluation is highly important in liver disease and after liver transplantation.

Binge ethanol intake in chronically exposed rat liver decreases LDL-receptor and increases angiotensinogen gene expression

AIM: To investigated the status of low-density lipoprotein (LDL)-receptor and angiotensionogen gene expression in rats treated chronically with ethanol followed by binge administration, a model that mimics the human scenario. METHODS: Rats were chronically treated with ethanol in liquid diet for 4 wk followed by a single binge mode of ethanol administration (5 mg/kg body weight). Samples were processed 4 h after binge ethanol administration (chronic ethanol binge). Control rats were fed isocaloric diet. In the control for binge, ethanol was replaced by water. Expression of mRNA for angioten-sinogen, c-fos and LDL-receptor, and nuclear accumulation of phospho-extracellular regulated kinases (ERK)1/2 and ERK1/2 protein were examined. RESULTS: Binge ethanol administration in chronically treated rats caused increase in steatosis and necrosis. Chronic ethanol alone had negligible effect on mRNA levels of LDL-receptor, or on the levels of nuclear ERK1/2 and phospho-ERK1/2. But, chronic ethanol followed by binge caused a decrease in LDL-receptor mRNA, and also decreased the levels of ERK1/2 and phospho-ERK1/2 in the nuclear compartment. On the other hand, chronic ethanol-binge increased mRNA expression of angiotensinogen and c-fos. CONCLUSION: Binge ethanol after chronic exposure, causes transcriptional dysregulation of LDL-receptor and angiotensinogen genes, both cardiovascular risk factors.

2型糖尿病患者血清PTX3、sTWEAK水平与非酒精性脂肪性肝病的关系研究

目的探讨2型糖尿病(T2DM)患者血清正五聚蛋白3(PTX3)、可溶性肿瘤坏死因子样凋亡弱诱导因子(sTWEAK)水平与非酒精性脂肪性肝病(NAFLD)的关系。方法选取北部战区总医院152例新诊断为T2DM的患者为研究对象,根据是否合并NAFLD将患者分为NAFLD组(92例)和非NAFLD组(60例);根据肝脏超声检查结果,将NAFLD患者分为轻度组、中度组和重度组。另选取35例健康人作为对照(对照组)。采用酶联免疫吸附试验检测血清PTX3、sTWEAK水平。采用Pearson相关分析T2DM患者PTX3和sTWEAK水平与总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、空腹血糖(FPG)、糖化血红蛋白(HbA1c)、胰岛素抵抗指数(HOMA-IR)的关系。采用多因素Logistic回归分析T2DM合并NAFLD的影响因素;采用受试者工作特征(ROC)曲线分析PTX3、sTWEAK对NAFLD的预测价值,计算曲线下面积(AUC)。比较轻度组、中度组、重度组血清PTX3、sTWEAK水平。结果与对照组比较,NAFLD组和非NAFLD组血清PTX3、sTWEAK水平较高(P<0.05)。与非NAFLD组比较,NAFLD组血清PTX3、sTWEAK水平较高(P<0.05)。体质量指数(BMI,OR=3.387)、TG(OR=1.958)、HOMA-IR(OR=3.040)、PTX3(OR=4.836)、sTWEAK(OR=4.133)是T2DM合并NAFLD的影响因素(P<0.05)。T2DM患者血清PTX3水平分别与BMI、LDL-C、FPG、HbA1c、HOMA-IR呈正相关(P<0.05),而与HDL-C呈负相关(P<0.05)。血清sTWEAK水平分别与LDL-C、FPG、HOMA-IR呈正相关(P<0.05)。血清PTX3、sTWEAK预测T2DM患者发生NAFLD的AUC分别为0.873和0.821,二者联合可将AUC提高至0.915。轻度组、中度组、重度组血清PTX3和sTWEAK水平比较,差异有统计学意义(P<0.05),病情越重,患者血清PTX3和sTWEAK水平越高。结论PTX3、sTWEAK是T2DM患者发生NAFLD的影响因素,并且血清PTX3、sTWEAK水平越高,NAFLD病情越重。

肝X受体α(LXRα)及三磷酸腺苷结合盒转运体A1(ABCA1)参与子痫前期发病的机理研究

目的探讨在子痫前期发病中LXRα和ABCA1的变化及二者与脂质代谢异常的关系。方法选取2019年10月至2023年6月在福建医科大学附属泉州第一医院妇产科分娩的子痫前期孕妇112例(子痫前期组),根据妊娠34周前是否诊断为子痫前期,将其分为早发组和晚发组;同期住院生产的70名正常孕产妇为正常对照组(正常组),采用生化方法测得血清中血脂水平(TG、TC、LDL及HDL);采用ELISA法检测2组患者血清中的LXRα与ABCA1蛋白表达水平;采用免疫组化及半定量PCR(RT-PCR)检测正常组及子痫前期组胎盘组织中LXRα与ABCA1的表达。分析LXRα和ABCA1表达与血脂异常的关系。结果子痫前期组TG、TC、LDL高于正常组,HDL低于正常组,差异均具有统计学意义(均P<0.05)。RT-PCR及免疫组化显示子痫前期组胎盘和血清的LXRα、ABCA1表达低于正常组(P<0.05)。胎盘上LXRαmRNA水平与LXRα蛋白表达水平呈正相关,差异具有统计学意义(P<0.05);两组患者血清ABCA1的表达水平与其胎盘上ABCA1蛋白浓度呈正相关,与血液循环中LDL的浓度水平呈负相关,与血液循环中HDL的浓度水平呈正相关,差异均有统计学意义(均P<0.05)。结论子痫前期妇女的血脂水平及血清中LXRα、ABCA1表达异常,且与病情严重程度相关;LXRα及ABCA1参与了子痫前期的血脂代谢异常的发生,可以作为临床上评判相关病程进展的依据。

有氧运动对高胆固醇血症大鼠肝脏低密度脂蛋白受体活性调节的影响

本文研究了实验性高胆固醇血症大鼠肝脏低密度脂蛋白受体（ＬＤＬＲ）活性变化及有氧运动时ＬＤＬＲ活性调节的影响。发现，高脂（ＨＣ）组肝组织匀浆ＬＤＬＲ活性较正常对照（ＮＣ）组降低３７％（Ｐ＜０．０５），同时血清总胆固醇（ＴＣ）、低密度脂蛋白胆固醇（ＬＤＬＣ）及血清载脂蛋白Ｂ（ＡｐｏＢ）均显著高于ＮＣ组（Ｐ＜０．０１）；高脂＋运动（ＨＥ）组ＴＣ、ＬＤＬＣ及ＡｐｏＢ均明显低于ＨＣ组，而ＬＤＬＲ活性则较ＨＣ组增高２６％（Ｐ＜０．０５）。结果提示：（１）高胆固醇负荷时细胞可通过下行调节影响ＬＤＬＲ活性；（２）运动可能通过增加对细胞内胆固醇利用和降解，反馈作用于下行调节过程影响ＬＤＬＲ的合成，增加对ＬＤＬＣ摄取而显著改善血脂水平。

血清ox-LDL与非酒精性脂肪肝超声检查关系的探讨

目的探讨不同程度非酒精性脂肪肝(NAFLD)患者血清氧化低密度脂蛋白(ox-LDL)水平及其与代谢指标的相关性。方法采用酶联免疫吸附试验(ELISA)检测79例NAFLD患者和23名正常对照者血清oxLDL浓度,同时测定肝功能、代谢指标及血清同型半胱氨酸(Hcy)水平,根据B超检查结果将79例NAFLD患者分为轻(40例)、中(25例)、重度(14例)脂肪肝。分析ox-LDL与其他指标及脂肪肝程度的相关性。结果 NAFLD组丙氨酸氨基转移酶、γ谷氨酰基转移酶、甘油三酯、总胆固醇、低密度脂蛋白胆固醇、载脂蛋白B、载脂蛋白E、Hcy、尿酸、空腹血糖、纤维连接蛋白及ox-LDL水平均明显高于正常对照组(P均<0.05)。中、重度脂肪肝组血清ox-LDL水平明显高于轻度脂肪肝组(P均<0.05)。ox-LDL与Hcy、尿酸、总胆汁酸呈正相关关系[相关系数(r)为0.375、0.369和0.395,P值分别为0.007、0.013和0.029],ox-LDL水平与脂肪肝的分级呈正相关(r=0.410,P=0.011)。结论随着脂肪肝程度的加重,NAFLD患者血清ox-LDL水平逐渐升高。ox-LDL是肝功能受损及脂肪肝进展过程中的重要因素,对临床诊断和病情监测有重要意义。

槐角总黄酮对高脂血症大鼠降血脂及抗氧化能力的实验研究

目的:观察槐角总黄酮对高脂血症大鼠的降血脂及抗脂质过氧化作用.方法:用高脂饲料喂养大鼠4wk,建立实验性高脂血症大鼠模型,给予槐角总黄酮40,80,160mg/kg体质量,连续6wk,以绞股蓝总皂苷为阳性对照,检测血清总胆固醇(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)含量;测定血液黏度、肝脏丙二醛(MDA)含量、超氧化物歧化酶(SOD)活力及总抗氧化能力(T-AOC)的变化;逆转录-多聚酶链反应(RT-PCR)检测肝低密度脂蛋白受体(LDL-R)基因mRNA的表达.结果:槐角总黄酮能降低高脂血症大鼠血清TC,TG,LDL-C水平(P<0.05或P<0.01),升高HDL-C水平(P<0.05);降低全血黏度,使肝组织MDA水平降低,SOD及T-AOC活力升高,促进LDL-R基因mRNA的表达.结论:槐角总黄酮对高脂血症模型大鼠脂代谢紊乱具有较好的调节作用,可能是通过降低血液黏度、抗脂质过氧化,对肝LDL-R基因mRNA表达的调控来实现其降脂作用.

脂蛋白、钙拮抗剂对大鼠贮脂细胞的影响

目的观察脂蛋白、钙拮抗剂对大鼠贮脂细胞增殖、透明质酸及胶原合成的影响．方法通过ＭＴＴ法，透明质酸放射免疫分析法及３Ｈ脯氨酸掺入法测定了低密度脂蛋白（ｌｏｗｄｅｎｓｉｔｙｌｉｐｏｐｒｏｔｅｉｎ，ＬＤＬ）、钙拮抗剂尼卡地平（Ｎｉｃａｒｄｉｐｉｎｅ，Ｎｉｃ）和维拉帕米（Ｖｅｒａｐａｍｉｌ，Ｖｅｒ）及其联合应用对大鼠贮脂细胞（ｆａｔｓｔｏｒｉｎｇｃｅｌ，Ｆｓｃ）增殖、透明质酸（ｈｙａｌｕｒｏｎｉｃ，ＨＡ）及胶原合成的影响．结果ＬＤＬ能促进ＦＳＣ增殖、ＨＡ及胶原合成，同时Ｎｉｃ及Ｖｅｒ对ＬＤＬ刺激引起的ＦＳＣ增殖、胶原合成有明显的抑制作用，但对ＨＡ的抑制作用不明显．结论ＬＤＬ参与ＦＳＣ的增殖及细胞外基质的合成。

蒲黄对动脉粥样硬化大鼠肝脏低密度脂蛋白受体基因的影响

目的:探讨蒲黄对动脉粥样硬化(AS)大鼠模型低密度脂蛋白受体(LDLR)基因表达的影响。方法:实验采用一次性腹腔注射维生素D3加喂饲高脂饲料复制动脉粥样硬化动物模型。蒲黄混悬液低、中、高剂量按2g/kg、4g/kg、8g/kg体重3个剂量灌胃给药,每天一次,连续8周,同时喂饲高脂饲料,第6周、8周分别取肝组织,应用逆转录-聚合酶链反应(RT-PCR)技术检测低密度脂蛋白受体信使核糖核酸(mRNA)水平。结果:蒲黄高剂量组LDLR mRNA相对含量高于模型组,差异具有显著性;蒲黄中、低剂量组LDLR mRNA相对含量与模型组相比无差异。结论:高剂量的蒲黄可以调节脂质代谢紊乱,抗AS的形成,其机制与上调肝LDLR mRNA表达有关。

FGF-21通过上调肝脏LDL受体的表达降低血浆中LDL水平

目的成纤维细胞生长因子-21(FGF-21)可降低实验动物血浆中的低密度脂蛋白(LDL)的浓度,但其作用机制尚不清楚,本实验试图通过研究FGF-21对LDLR的调节作用揭示FGF-21调节血浆LDL浓度的机制。方法向谷氨酸钠(MSG)肥胖大鼠连续注射FGF-21蛋白40d后,检测其血浆中LDL的变化,并用荧光定量PCR的方法结合免疫荧光检测FGF-21对肝脏组织中LDLR mRNA及蛋白的影响。结果 MSG肥胖鼠经FGF-21处理,血浆内的LDL降低18%,其肝脏组织中LDLR mRNA含量提高9倍;HepG2细胞内的LDLR mRNA表达量随FGF-21处理时间增加而提高,且呈剂量依赖性;流式细胞仪检测显示,经FGF-21处理后HepG2细胞表面LDLR蛋白数量增加。结论 FGF-21通过增加肝细胞的LDLR表达量从而降低血浆中LDL浓度。

血清小而密低密度脂蛋白胆固醇与脂肪肝相关性分析

目的探讨血清小而密低密度脂蛋白胆固醇(sdLDL-C)在脂肪肝患者中变化情况及其与脂肪肝的相关性。方法收集来笔者医院健康体检人群1012例,根据B型超声检测结果分为脂肪肝组442例(男性/女性:309/133)和非脂肪肝组570例(男性/女性:311/259)。血清sdLDL-C检测采用过氧化物酶法。结果脂肪肝组sdLDL-C水平显著高于非脂肪肝组(1.09±0.44mmol/L vs 0.77±0.35mmol/L,P=0.000)。多元线性回归分析显示,sdLDL-C与总胆固醇(TC)、甘油三酯(TG)和丙氨酸氨基转移酶(ALT)呈正相关(P=0.000),与高密度脂蛋白胆固醇(HDL-C)呈负相关(P=0.000)。Logistic回归分析显示,控制基础指标和肝功能指标ALT后,sdLDL-C与脂肪肝具有独立的相关性(P=0.000),但增加血脂指标TC、TG和HDL-C变量后,sdLDL-C不再与脂肪肝具有独立相关性(P=0.349)。结论脂肪肝患者sdLDL-C显著增高,sdLDL-C不是脂肪肝患病的独立危险因素,降脂治疗是降低血循环中sdLDL-C水平的主要靶点。

重度脂肪肝与血脂异常的相关性研究

目的:探讨脂肪肝病情严重程度与血脂异常之间的相关性。方法:选取200例脂肪肝患者为脂肪肝组,其中轻度44例,中度102例,重度54例,选取肝脏无明显异常中老年体检者100例为对照组,检测两组血脂浓度。结果: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)脂肪肝组分别为(5.57±1.38)、(3.13±2.18)、(0.92±0.26)、(3.71±0.93)mmol/L,对照组为(4.24±0.75)、(1.34±0.82)、(1.21±0.28)、(2.19±0.78)mmol/L,两组比较差异具有统计学意义(P<0.05);轻度脂肪肝患者为(4.98±0.95)、(1.43±0.99)、(1.15±0.26)、(2.43±0.80)mmol/L,中度为(5.63±1.14)、(2.32±1.81)、(1.06±0.25)、(3.15±0.91)mmol/L,重度为(6.14±1.56)、(3.48±2.35)、(0.87±0.28)、(3.82±0.94)mmol/L,不同分度脂肪肝患者之间比较差异具有统计学意义(P<0.05);非条件Logistic多因素回归分析结果显示TG是引起脂肪肝患病的独立危险因素(P<0.05),相关性分析脂肪肝病情严重程度与TC、TG、LDL-C浓度之间具有正相关(P<0.05),与HDL-C浓度之间具有弱负相关(P<0.05)。结论:脂肪肝病情严重程度与血脂水平异常之间具有密切相关性。

肝细胞膜低密度脂蛋白受体酶联免疫测定法的建立

实验建立了检测肝细胞膜低密度脂蛋白受体的抗配体抗体酶联免疫吸附测定法．测定中，固相膜受体蛋白量由包放前后膜蛋白浓度差值计算确定；低密度脂蛋白结含量按双抗体夹心法制作的低密度脂蛋白标准曲线确定，膜蛋白非村异吸附则用与酶联抗体来源相同的同种动物血浆低密度脂蛋白平行抑制试验消除．兔肝细胞膜低密度脂蛋白受体结合活性经Scatchard作图，Kd＝13．6mg／L，Bmax＝124μg／g膜蛋白（n=5）．测定结果说明建立的方法安全可靠，能反映受体的结合活性，在高脂血症及心血管病的研究中具有广泛的应用价值．本研究还对选择确定受体包被浓度、酶交联物稀释度等的棋盘滴定方法作了详细介绍和讨论．

血管紧张素Ⅱ灌注在脂质肝损伤中的作用研究

目的:通过制备血管紧张素Ⅱ(AngⅡ)灌注模型,观察AngⅡ在脂质肝损伤中的作用及其可能的机制。方法:将C57BL/6小鼠随机分为对照组、AngⅡ灌注组及AngⅡ灌注加AngⅡ1型受体(AT1R)基因敲除组。采用HE、菲律宾、油红0染色以及胞内胆固醇定量测定法观察肝细胞内脂质沉积情况;免疫组化、蛋白质印迹法检测低密度脂蛋白受体(LDLR)、固醇调节元件结合蛋白2(SREBP-2)及其裂解激活蛋白(SCAP)表达水平。结果:AngⅡ刺激增加C57BL/6小鼠肝细胞内脂质沉积,且上调LDLR、SREBP-2和SCAP的表达。而AT1R基因敲除组C57BL/6小鼠肝细胞内脂质沉积明显减少,LDLR通路的相关蛋白表达也显著下调。结论:AngⅡ通过AT1R诱导LDLR负反馈调节失调,进而增加胆固醇内流、肝细胞内脂质过度沉积,介导脂质肝损伤的发生。

胰岛素抵抗在非酒精性脂肪肝发病中的作用

目的:探讨胰岛素抵抗(IR)在非酒精性脂肪肝(NAFL)大鼠脂肪肝模型中的作用机制.方法:大鼠随机分为空白对照组,脂肪肝模型对照组(模型+生理盐水组)和脂肪肝实验组(模型+罗格列酮组).其中脂肪肝模型对照组和脂肪肝实验组分别予生理盐水和马来酸罗格列酮干预治疗4wk.观察各组大鼠肝脏大体形态和组织学改变;检测空腹血糖(FPG),空腹血胰岛素水平(FINS),计算胰岛素抵抗指数(IRI);检测血浆ApoCⅡ、ApoCⅢ水平及血浆脂蛋白脂肪酶(LPL)、肝脂肪酶(HL)活性和大鼠肝组织ApoB-100mRNA的表达量.结果:治疗前,脂肪肝组大鼠(包括脂肪肝模型组和脂肪肝实验组)与空白对照组大鼠比较,肝脏组织学改变达到脂肪肝诊断标准,FPG、FINS明显升高(6.46mmol/L±0.75mmol/L,6.61mmol/L±0.45mmol/L vs5.48mmol/L±0.47mmol/L;78.82mU/L±11.13mU/L,78.48mU/L±12.94mU/Lvs40.90mU/L±7.76mU/L),IR也明显升高(22.48±2.81,22.98±3.47vs9.85±1.15),血浆ApoCⅡ水平降低、ApoCⅢ水平升高,LPL和HL酶活性均降低,肝组织ApoB-100mRNA的表达量降低.马来酸罗格列酮干预治疗4wk后,与脂肪肝模型对照组比较,脂肪肝实验组大鼠肝脏大体标本和组织学脂肪变性情况明显减轻,FPG,FINS降低(6.01mmol/L±0.56mmol/Lvs6.43mmol/L±0.47mmol/L,68.11mU/L±10.52mU/L vs82.48mU/L±15.20mU/L),IR降低(18.49±2.44vs23.39±3.16),血浆ApoCⅡ水平升高,ApoCⅢ水平降低,LPL和HL酶活性均增加,肝组织ApoB-100mRNA的表达量上升.结论:高脂肪高胆固醇饮食可以成功造成SD大鼠有IR的NAFL模型.通过改善脂肪肝大鼠的IR,可以改变血浆ApoCⅡ、ApoCⅢ水平来提高LPL和HL的酶活性,加速外周VLDL和TG的降解,促使肝组织ApoB-100mRNA的表达量上升,VLDL在肝脏合成加快,从而加快内源性TG的转运,减轻肝细胞脂肪浸润.