Intracellular sterol trafficking

Summary Sterols are acquired by cells either biosynthetically by the interaction of cytoplasmic and endoplasmic reticulum elements, or by endocytosis. The subcellular distribution of sterols, however, argues that sterols are trafficked quickly from sites of acquisition to target membranes, particularly the plasma membrane. The mechanisms mediating this movement might include aqueous diffusion, vesicles of either a unique pathway or of the protein secretory pathway, or carrier proteins. These mechanisms are discussed and the limited data concerning each are presented. Finally, a theory is proposed which describes how sterols and other membrane reinforcing molecules might have driven the evolution of intracellular membranes, thus establishing the dynamic membrane system of modern eukaryotes.     

氧化甾醇-磷脂脂质囊泡的制备及特性研究

 氧化甾醇3,19–二羟基-胆甾烷-24-酮（DHCO）和3β,5α,6β-胆甾烷三醇（Triol）替代胆甾醇与大豆磷脂形成脂质囊泡的性质研究。采用乙醇注入法制备脂质囊泡,通过测定脂溶性及水溶性荧光探针在脂质囊泡中的荧光强度变化,考察囊泡膜流动性及通透性;通过测定脂质囊泡中游离DHCO及结合DHCO的浓度考察DHCO与磷脂的结合率;考察DHCO/磷脂比例、超声条件对脂质囊泡粒径大小和分布的影响。结果表明,DHCO、Triol与磷脂形成的脂质囊泡与胆甾烷（CHOL）-磷脂脂质囊泡的膜流动性无明显差异,但膜通透性稍有增大。DHCO与磷脂的结合率为8258%。DHCO、Triol与大豆磷脂经简单工艺即可形成脂质囊泡。可通过调节DHCO/磷脂比例、超声条件获得具理想粒径和外观的脂质囊泡。氧化甾醇数量庞大,其作为脂质囊泡的新型“流动性缓冲剂”有巨大的发展潜力。     

大豆蛋白的营养保健功能研究现状

阐述了大豆蛋白的营养功能和保健功能研究现状,重点介绍大豆蛋白在调节血脂、改善胰岛素敏感性和减肥功效上的作用及其机理研究,并对我国大豆蛋白行业发展现状进行了概述和展望,指出振兴大豆蛋白产业对提高国人蛋白摄入质量和缓解我国慢性病高发现状具有重要意义.     

高糖高胆固醇诱导EA.hy926细胞凋亡中对HSPD1基因表达的影响

用高糖（25mmol/L葡萄糖）和胆固醇（0.8, 1.6, 3.2mmol/L）处理EA.分析高糖高胆固醇诱导EA.hy926细胞凋亡中对HSPD1基因表达的影响,研究表明随胆固醇浓度的增加,EA.hy926细胞活性下降,呈浓度依赖性.0.8mmol/L胆固醇低糖培养液培养12h的细胞活性与正常对照组无显著差异（P>0.05）,而0.8mmol/L胆固醇高糖培养液培养12h的细胞活性与正常对照组（高糖培养液+0mmol/L胆固醇）具显著性差异(P<0.01).低糖或高糖培养液+0.8mmol/L胆固醇处理EA.hy926细胞不同时间后,细胞活性呈时间依赖性下调,48h后细胞大部分变圆,脱落.高糖高胆固醇处理的细胞大部分发生凋亡（50%）,HSPD1基因表达显著上调.     

低密度脂蛋白胆固醇、载脂蛋白B与颈动脉粥样硬化斑块的关系

目的 :观察颈动脉粥样硬化患者颈动脉的结构变化及粥样硬化斑块情况 ,研究低密度脂蛋白胆固醇 (L DL - C)、载脂蛋白 B(Apo B)与颈动脉粥样硬化斑块的关系。方法 :测定 10 0例患者空腹血中 L DL - C、Apo B浓度 ,并行颈动脉超声检查 ,测量斑块面积 ,并计算斑块积分和斑块指数。分别计算 L DL - C、Apo B与颈动脉粥样硬化斑块总积分的相关性。按 L DL - C/ Apo B比值分组 ,计算各组的平均斑块指数。结果 :L DL - C、Apo B与颈动脉粥样硬化斑块总积分之间均呈正相关 ,且二者的相关性相当 (r=0 .6 6 5 7,P<0 .0 1;r=0 .6 86 4 ,P<0 .0 1)。L DL - C/ Apo B<1.2 5组颈动脉粥样硬化斑块指数比 L DL - C/ Apo B>1.6 2组高 ,两者相比有显著性差异 (1.76± 0 .80 ,3.30± 1.4 6 ;P<0 .0 5 )。结论 :L DL - C、Apo B与颈动脉粥样硬化斑块的形成均有密切关系 ,其中 Apo B与颈动脉粥样硬化斑块的关系更密切     

Opposite pattern of MDR1 and caveolin-1 gene expression in human atherosclerotic lesions and proliferating human smooth muscle cells

Cholesterol esterification and smooth muscle cell (SMC) proliferation are the crucial events in the development of atherosclerotic lesions. The objective of this study was to analyse cholesterol esterification and the expression of MDR1 (multidrug resistance), ACAT (acyl-CoA:cholesterol acyltransferase) and caveolin-1 genes in atherosclerotic and healthy vascular walls, in SMCs obtained from atherosclerotic lesions and saphenous veins. Results demonstrated higher levels of cholesterol esters, ACAT and MDR1 mRNAs and lower levels of caveolin-1 mRNA in atherosclerotic segments compared to adjacent serial sections of the same artery and the corresponding non-atherosclerotic arteries from cadaveric donors. SMCs isolated from atherosclerotic plaques manifested an increased capacity to esterify cholesterol and to grow at a faster rate than SMCs isolated from saphenous veins. In addition, when SMCs from atherosclerotic plaques were cultured in the presence of progesterone, a potent inhibitor of cholesterol esterification, significant growth suppression was observed. An increase in ACAT and MDR1 expression and a concomitant decrease in caveolin-1 expression were also observed in SMCs isolated from atherosclerotic arteries as early as 12 h after serum stimulation. An opposite pattern was found when SMCs were treated with progesterone. These findings support the idea that cholesterol esterification plays a role both in early atherogenesis and in clinical progression of advanced lesions and raise the possibility that the cholesterol ester pathway might directly modulate the proliferation of SMCs. Received 5 February 2001; received after revision 15 May 2001; accepted 15 May 2001     

Relationship between DNA and cholesterol synthesis in kidney after refeeding

Summary DNA and cholesterol synthesis were investigated in the kidneys of fasted-refed rats. Refeeding resulted in an increase in kidney DNA synthesis, as measured by³H-thymidine incorporation, starting at 72 h. The increase in DNA synthesis was accompanied by a stimulation of cholesterol synthesis, as measured by¹⁴C-acetate incorporation into cholesterol.     

Crystallogeny fundamentals of the cholesterol gallstone

The nucleation mechanism and crystal growth process of the cholesterol gallstone are studied and a systematic theory expounded by crystallogeny is proposed. Normal feed and stone-forming feed were used to raise guinea pigs in the control and stone-causing groups respectively. The state and transformation of liquid crystal vesicles, the appearance of crystal nuclei, and the formation of microcrystal grains were observed under a polarizing microscope during the experimental period. It was found that the liquid crystal vesicles in the bile of the control group were small, scattered, and always existed as single forms, and no shaped gallstone crystals were formed. While in the stone-causing group, liquid crystal vesicles grew to larger ones, and then aggregated to form large liquid crystal cells. Solid crystal growth along the edge of these liquid crystal cells formed microcrystal grains. These demonstrated that bile liquid crystal vesicles form the basic nuclei of cholesterol gallstone. Heterogeneous nucleation is the common process in the formation of crystal nuclei and crystal growth.     

Cholesterol content and cholesterol esterifying activity of various organs in guinea pigs

Summary In various organs of the guinea pig, the total cholesterol content of an organ was significantly correlated with the percentage of esterified cholesterol present in this organ. Cholesterol esterifying capacity was shown in most organs, with highest activities in the adrenals, the spleen and the liver. The significant correlation found between the cholesteryl ester content of an organ and its acyl cholesterol acyltransferase activity suggests a possible role of this enzyme in determining the level of the total and esterified cholesterol in a tissue.This work was supported by a grant Crédit aux Chercheurs du Fonds National de la Recherche Scientifique of Belgium.Acknowledgments. I am indebted to Prof. C. Harvengt for his stimulating interest and helpful suggestions. I wish to thank Y. van Nieuwenhuyze and J. Costermans for their valuable laboratory assistance and Dr H. Baudon for pathological studies.