加强对小肠吸收功能与胆石病发生关系的研究

20世纪早期,胆石病(主要指胆囊结石)很自然地被认为与胆囊有关,这是由于胆囊壁炎症为主要的发病原因,脱落的细胞成为胆汁胆固醇的来源.到了60～70年代,Small和Carey的研究建立了胆汁胆固醇过饱和是胆石形成物理化学基础的学说,肝脏分泌的过量胆固醇构成最主要的发病因素,由此认为胆石病是与肝脏代谢性缺陷相关的疾病.     

胆固醇结石病人肝脏脂质代谢异常的分子生物学研究

目的:研究导致胆石病人胆汁胆固醇过饱和的肝脏胆固醇和胆汁酸代谢途径中的分子生物学改变。方法:收集22例胆石病人和13例无胆石病的对照病人肝脏活检组织、胆囊胆汁和血浆。采用实时定量PCR检测肝脏基因表达,采用Western印迹法测定蛋白含量。结果:胆石病人较对照组ABCG5/ABCG8和LXRα基因的mRNA表达水平分别增加51%、59%和102%。肝脏SRBI的mRNA和蛋白含量均增加。结论:胆石病人ABCG5/ABCG8基因表达上调,可能与LXRα表达增加促进相关,这些异常是导致胆汁胆固醇过饱和的原因。此外,胆汁中过多的胆固醇可能来源于经肝脏高密度脂蛋白受体SRBI的摄取,而不是由于肝脏合成和酯化的异常。     

胆囊结石发病机制的当前认识

胆囊结石是普外科常见的疾病，其中大多数结石中胆固醇含量超过50％，属于胆固醇结石。自上世纪60年代，国内外研究者对胆石发生机制的探索形成了3个共识，成为胆石病的经典学说：①胆汁中胆固醇过饱和，是胆囊结石发生的必要条件与胆石形成的基础；②胆汁中促／抗成核因子平衡的破坏，     

胆结石研究的展望

胆结石研究有一百多年的历史,但30年以前多集中在胆石的形态学及化学成份上,直到近30年才有了极其显著的进步。1968年,Small三角的胆汁胆固醇过饱和学说阐述了胆固醇结石形成的理化基础,1966年Maki提出结合胆红素酶水解的观点,成为胆红素结石形成的主要机制。他们是近代胆石研究的里程碑,也是第一个研究高潮。此后的胆石研究进入高潮。胆石动物模型和临床病人的研究证实了胆固醇结石形成的三个缺陷,肝脏分泌过饱和胆汁的缺陷、胆汁成核的     

胆固醇结石病人肝脏胆小管侧膜ATP基因表达差异的研究

目的:本研究旨在测定比较胆石病人与对照组肝脏胆小管侧膜转运蛋白表达差异,以探讨胆石病发生的分子生物学机制。方法:研究包括20例胆囊胆固醇结石病人和11例无胆石症的对照。测定血清胆固醇和甘油三酯、胆汁胆固醇、胆汁酸和磷脂含量,采用Carey表计算胆汁胆固醇饱和指数。实时定量PCR法测定肝脏胆小管侧膜转运蛋白(ABCG5、ABCG8、ABCBll和ABCB4)mRNA的表达量。结果:胆石组血清胆固醇低于对照组(P<0.05)。胆石组胆汁胆固醇摩尔百分比和胆固醇饱和指数较对照组显著升高(P<0.01)。胆石组肝脏胆小管侧膜胆固醇转运蛋白ABCG5和ABCG8表达高于对照组,且后者差异具有统计学显著性(ABCG5:31.44±3.17Vs25.72±3.27,ABCG8:27.53±3.06vs17.81±2.23)。ABCBll和ABCB4表达在两组间差异无显著性。结论:本研究显示,胆石病主要病理生理异常为胆汁胆固醇过饱和,与肝脏胆小管侧膜胆固醇转运蛋白ABCG5和ABCG8的mRNA表达增加有关。     

尼曼匹克C1样1蛋白与胆固醇结石病

<正>胆囊结石占胆石病的绝大部分,主要成分是胆固醇,因而称为胆固醇结石病(简称胆石病),其主要发病机制是体内胆固醇代谢紊乱,表现为胆汁胆固醇过饱和,进一步在胆囊内成核形成胆固醇结晶,最终导致胆固醇结石形成。机体胆固醇代谢包括若干过程:胆固醇的重新合成、肠道吸收食物与胆汁来源的胆固醇以及肝脏向胆汁分泌胆固醇等。     

胆固醇结石病人肝脏SRBI及其转录调节因子LRH-1基因表达的研究

目的:研究胆固醇结石病人BI型清除剂受体(scavengerreceptorBtypeI,SRBI)及其转录调节因子肝脏受体类似物1(liverreceptorhomologue1,LRH-1)的表达,以探讨胆固醇结石发病的机制。方法:对20例胆囊胆固醇结石病人和10例无胆石症对照者测定血清脂质、胆汁成分和计算胆汁胆固醇饱和指数。以实时定量PCR法测定肝脏SRBI和LRH-1mRNA的表达量。结果:胆石组胆石平均胆固醇含量(86.68±5.26)%,均为胆固醇结石。胆石组病人血清高密度脂蛋白(HDL)显著低于对照组[(0.86±0.62)mmol/L比(1.42±0.56)mmol/L,P<0.01]。胆石组胆汁胆固醇在总脂中的摩尔百分比和胆固醇饱和指数显著高于对照组[(7.80±2.06)mol%比(5.26±2.80)mol%,P<0.05]。胆石组SRBI基因mRNA表达量与对照组比较显著增高(2.48±0.44比1.00±0.23,P<0.05),胆石组LRH-1表达也高于对照组(2.05±0.29比1.00±0.28,P<0.05)。结论:胆固醇结石病的主要病理生理异常为胆汁胆固醇过饱和。肝脏LRH-1、SRBI表达增高,参与了胆固醇过饱和胆汁形成,并促进了胆固醇结石形成。     

载脂蛋白B基因XbaⅠ多态性和胆囊结石病关系研究

目的 研究载脂蛋白B基因Xba Ⅰ多态性和胆石病关系。方法对75例胆囊结石病人与112例对照者确定APOB基因Xba Ⅰ多态性的基因型，并对其中41例胆囊切除术病人和11例对照者分析胆汁成分。结果胆石组携带X＋／基因型和X＋等位基因的频率显著高于对照组（P〈0．05）。胆石组病人胆汁胆固醇摩尔百分比和胆固醇饱和指数显著高于对照组，而总脂质降低，差异具有统计学意义。携带X＋等位基因的胆石病人胆汁胆同醇摩尔百分比和胆固醇饱和指数高于X-／-纯合子病人，而总脂质降低。结论 X＋等位基因可能是胆石病的易感基因之一。     

磷脂代谢紊乱在胆固醇结石形成中的作用(文献综述)

最近十多年对胆囊结石(后文简称胆石)发病机理的研究,人们渐渐认识到肝脏代谢功能紊乱分泌胆固醇过饱和胆汁、胆囊内促成核因子增加和胆囊收缩功能下降是胆石形成过程中的三个必不可少环节.在成核因子中,粘糖蛋白的促成核作用尤其引人关注,这是一种高分子的糖蛋白多聚物,是胆囊上皮细胞分泌的主要物质.本文将着重讨论磷脂代谢紊乱与粘糖蛋白分泌的关系.胆汁磷脂的组成和磷脂的功能胆汁磷脂中80～95%为磷脂酰胆碱(PC),其余还有磷脂酰乙醇胺(PE)、磷脂酰肌醇(PI)、磷脂酰丝氨酸(PS)及鞘磷脂(SM)等物质.正常肝胆汁和致石肝胆汁中都不含溶血磷脂酰胆碱(LPC),无菌的胆囊胆汁中磷脂酶A_2(PLA_2)也无活性.人胆汁中,70～80%PC是Sn-1软脂酰、Sn-2油酰、亚油酰或花生四酰.磷脂是胆汁中的四种主要成份之一,它在胆汁中     

肝脏核受体LXRs/FXR在胆固醇结石病防治领域中的研究进展

胆囊胆固醇结石前提发病条件为胆囊胆汁中的胆固醇／胆汁酸失衡导致胆固醇的过饱和。胆汁的形成和分泌主要由肝细胞来完成。肝细胞内胆固醇／胆汁酸代谢异常导致的肝细胞内胆固醇沉积与结石形成密切有关。本文就与胆固醇／胆汁酸代谢紧密相关的肝脏核受体LXRs／PXR在结石形成过程中的作用研究进展作一综述。     

Leptin-resistant obese mice have paradoxically low biliary cholesterol saturation

BACKGROUND: Human obesity is associated with leptin resistance, elevated serum glucose and lipids, hepatic steatosis, and cholesterol gallstone formation. These gallstones are thought to result from hypersecretion of biliary cholesterol as well as biliary stasis. Leptin-resistant Lep(db) obese mice, which are known to have elevated serum leptin, glucose, and lipids, as well as hepatic steatosis, should be an appropriate model for human gallstone formation. Therefore, we tested the hypothesis that leptin-resistant mice would have increased gallbladder volume, biliary cholesterol saturation, and cholesterol crystal formation. METHODS: Sixty lean control mice and 60 Lep(db) obese mice on a low cholesterol chow diet were studied. Gallbladder volumes were measured and bile was pooled to calculate cholesterol saturation index. Serum cholesterol, glucose, and leptin levels were determined from pooled serum. Hepatic fat vacuoles were counted. Bile from a second group of 90 lean control and 59 obese mice was observed microscopically for cholesterol crystal formation. RESULTS: Leptin-resistant obese mice have significantly higher serum cholesterol, glucose, and leptin levels, hepatic fat vacuoles, and gallbladder volume than lean control mice. However, biliary cholesterol saturation index and cholesterol crystal formation were significantly diminished in the obese mice. CONCLUSIONS: These data suggest that leptin-resistant Lep(db) obese mice have (1) increased gallbladder volume, (2) decreased biliary cholesterol saturation despite elevated serum cholesterol and hepatic steatosis, and (3) decreased in vitro cholesterol crystal formation. We conclude that the link between obesity and gallstone formation does not require hypersecretion of biliary cholesterol.     

The effects of amiloride on biliary calcium and cholesterol gallstone formation.

Recent studies indicate that gallbladder absorption increases during the early stages of experimentally-induced cholesterol gallstone formation. The purpose of the present study was to ascertain whether pharmacologic inhibition of gallbladder ion transport and absorption reduces the incidence of experimentally-induced cholesterol gallstones. Prairie dogs were fed either a control chow or a 1.2% cholesterol-enriched chow for 15 days. One group of cholesterol-fed animals received saline via an orogastric tube; another group received amiloride, a drug known to inhibit in vitro ion transport in the prairie dog gallbladder. The incidence of gallstones in cholesterol-fed animals was reduced from 83% to 13% (p less than 0.025) when the animals were treated with amiloride; this occurred despite a cholesterol-saturation index comparable to that observed in gallstone animals. Additionally, although biliary calcium decreased in the gallbladder, hepatic bile did not in the amiloride-treated animals. These data provide further evidence that altered gallbladder absorption and increased biliary calcium are important factors in the pathogenesis of cholesterol gallstones.     

Ezetimibe抑制胆固醇结石形成的实验研究

目的 探讨ezetimibe（Eze）对胆囊胆固醇结石形成的抑制作用。方法 将30只雄性成年C57BL/6小鼠随机分为普通饲料喂养(chow)组、成石饲料喂养(LD)组和成石饲料加Eze组[Eze 5 mg/（kg·d）灌胃]。饲养8周后收集血清、肝脏、小肠和胆囊。观察胆囊内胆固醇结石形成情况。采用酶法测定血清、胆汁成分、肝组织胆固醇含量。采用实时定量PCR测定肝脏和小肠胆固醇代谢相关基因mRNA相对表达量。结果 chow组小鼠胆囊内未发现结石形成。LD组小鼠胆囊结石形成率为100%。Eze组完全无结石形成。Eze组小鼠小肠胆固醇吸收率(9.29%±4.32%),较LD组(58.62%±3.10%)和chow组(56.42%±2.67%)均显著降低（P<0.01）。LD组血清胆固醇[(4.99±0.50) mmol/L]和肝组织胆固醇含量[(22.92±2.39) mg/g]均较chow组[(2.87±0.06) mmol/L和(2.45±0.08) mg/g]显著增加（P<0.05）。Eze组血清胆固醇[(1.11±0.10） mmol/L]和肝组织胆固醇含量[(2.70±0.07) mg/g]均较LD组显著降低（P<0.05）。LD组小鼠胆汁胆固醇含量[LD组(10.87±1.46) mmol/L比chow组(3.67±0.58) mmol/L]和胆固醇饱和指数[LD组(1.42±0.19)比chow组(0.59±0.02)]显著增加。Eze组胆汁胆固醇含量[(2.72±0.29) mmol/L]和胆固醇饱和指数(0.57±0.07)均较LD组显著降低（P<0.01）。结论 Eze抑制小肠胆固醇肠道摄取,具有预防胆囊胆固醇结石形成的作用。     

核受体在胆结石形成中的作用机制

胆石症是临床常见病,特别是在女性和某些特殊种族群体.非水溶性胆固醇晶体的形成是由于胆汁中的胆固醇、胆盐、磷脂三个主要脂质之间的失衡造成的.而许多参与肝脏内胆汁脂质分泌的蛋白质是受几个转录因子所调控的,包括核受体肝脏X受体和胆汁酸受体.有证据证实,在人类以及小鼠的基因和病理生理中,胆结石的形成和这些核受体具有相关性.此外,最新的资料还表明,雌激素受体在异常胆固醇代谢中的作用会导致胆结石疾病的发生.因此,更好的研究核受体在胆结石形成中的作用机制,将有助于医师在临床工作中制订对胆结石疾病更有效的治疗策略.     

PDZK1敲除对小鼠肝脏胆固醇代谢和胆囊结石形成影响的实验研究

目的探讨敲除PDZK1(Postsynaptic density-95,disks-large,ZO-1-domain K1,PDZK1)基因对小鼠肝脏胆固醇代谢调节和胆囊结石形成的影响。方法雄性成年PDZK1基因敲除小鼠(PDZK1 knockout,KO组)和野生型小鼠(wild type,WT组),每组各10只,以成石饲料分别喂养4周,观察胆囊成石情况,并收集肝脏和胆囊组织。采用蛋白印迹法测定肝脏PDZK1和清道夫受体B族1型(scavenger receptor B type 1,SRB1)表达。采用胆总管插管收集肝胆汁,测定胆汁分泌率和胆汁胆固醇含量。采用试剂盒酶法测定胆囊胆汁成分并计算胆汁胆固醇饱和指数(cholesterol saturation index,CSI)。以实时定量PCR检测肝脏脂质代谢相关基因的mRNA表达。结果成石饲料喂养4周后,WT组小鼠全部成石(10/10),KO组小鼠则为40%(4/10)成石。两组小鼠肝胆汁分泌率差异无统计学意义,但KO组小鼠肝胆汁胆固醇含量显著降低(P0.05),胆汁酸含量增加(P0.05),且CSI降低(P0.05)。KO组小鼠肝脏SRB1蛋白表达降低(P0.05),甾醇氧-酰基转移酶基因1/2mRNA表达降低(P0.05),而肝型脂肪酸结合蛋白1和胆汁酸转运相关蛋白(ATP结合盒b11)表达则显著增加(P0.05)。结论 PDZK1影响SRB1在小鼠肝脏中表达,降低对高密度脂蛋白胆固醇摄取,减少胆汁胆固醇分泌,继而降低胆囊结石形成。     

脂蛋白脂酶,肝脂酶及载脂蛋白在兔胆囊结石中的变化及作用

目的研究脂蛋白脂酶,肝脂酶及载脂蛋白在兔胆囊结石中的变化及作用。方法采用日本杂交大耳兔５０只,随机分为对照组,１周组、２周组、３周组和４周组为实验组,实验组饲以１．２％高胆固醇膳食诱以胆囊结石,测定各组脂蛋白脂酶、肝脂酶、血清载脂蛋白和脂质的动态变化,脂蛋白脂酶和肝脂酶采用比色法测定,血清载脂蛋白采用圆周免疫扩散法测定,血清脂质采用酶法测定。结果随着高胆固醇膳食进食时间延长,２周组、３周组和４周组分别有４／１０,６／１０和７／１０只动物出现胆囊结石;肝素化血清中脂蛋白脂酶和肝脂酶活性增加,以３周组和４周组升高明显（与对照组比较,Ｐ＜０．０５）;血清载脂蛋白ａｐｏＢ１００,ａｐｏＣⅡ,ａｐｏＣⅢ明显增加（与对照组比较,Ｐ＜０．０５）,ａｐｏＡＩ在４周组时降低（与对照组比较,Ｐ＜０．０５）;血清总胆固醇,甘油三酯,磷脂,低密度脂蛋白胆固醇和极低密度脂蛋白胆固醇逐渐明显升高（与对照组比较Ｐ＜０．０５）,高密度脂蛋白胆固醇及其亚组份有降低趋势,但与对照组比较差异无显著性（Ｐ＜０．０５）。结论高胆固醇膳食后,脂蛋白脂酶和肝脂酶活性增强,血清载脂蛋白和酯质代谢异常变化,促进了胆囊结石形成。     

Ezetimibe ameliorates cholecystosteatosis

BACKGROUND: Cholecystosteatosis is the accumulation of gallbladder wall fats leading to decreased gallbladder emptying. Ezetimibe inhibits intestinal fat absorption and prevents murine gallstone formation. However, the influence of ezetimibe on gallbladder emptying and cholecystosteatosis has not been studied. Therefore, we tested the hypothesis that ezetimibe would improve gallbladder motility by preventing the buildup of fats in the gallbladder wall. METHODS: Forty lean female mice were fed either a control diet or a lithogenic diet for 6 weeks. Half of the mice on each diet received ezetimibe. At 11 weeks of age, all mice were fasted overnight and underwent gallbladder ultrasonography to determine ejection fraction. One week later, the mice were fasted and underwent cholecystectomy. Bile was examined for cholesterol crystals. The gallbladders were snap-frozen for lipid analysis. RESULTS: The lithogenic diet significantly (P < 0.05) increased serum cholesterol, biliary crystals, gallbladder wall cholesterol and cholesterol/phospholipid ratio, and decreased gallbladder ejection fraction. All of these abnormalities were reversed (P < 0.05) by the addition of ezetimibe to the diet. CONCLUSIONS: These data suggest that ezetimibe lowers serum cholesterol, prevents biliary crystals, and normalizes gallbladder wall fat and function. We conclude that ezetimibe ameliorates cholecystosteatosis and may be an effective agent for gallstone prevention.     

Stasis before gallstone formation: Altered gallbladder compliance or cystic duct resistance?

Gallbladder stasis occurs before gallstone formation and provides the link between the hepatic secretion of supersaturated bile and cholesterol cholelithiasis. We recently observed that cystic duct resistance increases while sphincter of Oddi resistance is unchanged in the presence of lithogenic bile without gallstones. Whether alterations in gallbladder function also lead to gallbladder stasis has been unclear. Therefore, we tested the hypothesis that before gallstone formation, stasis results from increased cystic duct resistance and altered gallbladder compliance. Adult, male prairie dogs were fed either a trace cholesterol (control) or a 0.4 percent cholesterol-enriched diet. Cystic duct resistance increased but gallbladder compliance was unchanged before gallstone formation. A significant correlation (p < 0.001) was found between the lithogenic index and cystic duct resistance in pregallstone animals. We conclude that increased resistance to flow across the cystic duct, and not altered gallbladder compliance, is etiologically related to bile stasis, an important event in gallstone formation.     

Interaction of chenodeoxycholic acid and dietary cholesterol in the treatment of cholesterol gallstones

Standard doses of chenodeoxycholic acid (15 mg/kg/day) fail to dissolve gallstones in 30 to 50 percent of patients with radiolucent gallstones in a functioning gallbladder. In humans, increasing dietary cholesterol produces increased biliary secretion of cholesterol. Restriction of dietary cholesterol reduces the minimum effective dose of chenodeoxycholic acid and speeds gallstone dissolution. In this study we investigated the interaction of dietary cholesterol and chenodeoxycholic acid in the prevention of gallstones in the prairie dog gallstone model. In animals fed a moderately lithogenic diet, standard doses of chenodeoxycholic acid failed to prevent gallstones. Reduction of the cholesterol stimulus or doubling the dose of chenodeoxycholic acid prevented the formation of gallstones. These findings support the hypothesis that the formation and dissolution of cholesterol gallstones are an expression of the relative strengths of saturating and desaturating stimuli. Therefore, rational therapy for cholesterol gallstone dissolution and prevention requires both reduction of lithogenic stimuli and optimal titration of chenodeoxycholic acid.     

Intestinal absorption and biliary secretion of cholesterol in rats with nephrotic syndrome

Background: Nephrotic syndrome (NS) results in hypercholesterolemia which is attributed to increased production and decreased removal of cholesterol-rich lipoproteins. Adjustments in intestinal absorption are reportedly involved in cholesterol homeostatis. We therefore, studied the intestinal absorption and biliary excretion of cholesterol in NS. Methods: We studied intestinal absorption (by in vivo perfusion and in vitro everted sac incubation techniques) and biliary secretion (by common bile duct cannulation) of cholesterol in rats with puromycin-induced NS. The results were compared with those obtained from pair-fed control (PF) animals, those given free access to food (NL) or those fed a hypercholerolemic diet (H-chol group). Micellar solutions of Krebs' phosphate buffer containing trace amounts of [¹⁴C]inulin and [³H]cholesterol, as well as different concentrations of unlabeled cholesterol, were used for absorption studies. Results: The NS and H-chol groups showed severe and comparable hypercholesterolemia. No significant difference was found in the rate of biliary cholesterol secretion among the study groups. Likewise, the rates of in vivo and in vitro cholesterol absorptions in the NS and H-chol groups were comparable with one another and similar to those found in the NL and PF groups. The rate of in vitro cholesterol absorption was directly proportional to its concentration in the incubation media at low concentrations. However, the absorption rate showed a pattern consistent with saturable transport at high cholesterol concentrations in all groups. Conclusions: We conclude that intestinal absorption and biliary secretion of cholesterol are not appreciably influenced by either nephrotic or diet-induced hypercholesterolemia in rats. The data further suggest that cholesterol absorption may be a saturable process.