Function and structure of high density lipoproteins during childhood

（一）.本文研究了两种含apoA-I的脂蛋白（一种仅含apoA-I（LpA-I），另一种含apoA-I和apoA-II（LpA-I/A-II））对巨噬细胞的作用。通过与放射性标记的乙酰化LDL孵育将大鼠巨噬细胞转化为泡沫细胞。与LpA-I或LpA-I/A-II孵育降低细胞胆固醇酯（CE）质量。然而，游离胆固醇（FC）质量仅由LPA-I降低。排泄到培养基中的所有放射性均与LpA-I或LpA-I/A-II相关; 39%的排泄放射性以LpA-I形式存在，10%以LpA-I/A-II形式存在。二硫代二硝基苯甲酸完全灭活卵磷脂：胆固醇酰基转移酶（LCAT）活性后，LpA-I的降胆固醇能力明显减弱。然而，LpA-I/A-II的CE质量减少能力不受影响。当LpA-I和LpA-I/A-II组合时，混合物的胆固醇降低能力与单独的LpA-I相似。 ...更多信息 然而，从培养基中再分离的LpA-I显示出比再分离的LpA-I/A-II更低的酯化率，从而表明在LpA-I中酯化的胆固醇被转移到LpA-I/A-II中。这些结果表明：（i）LpA-I的功能与LCAT活性密切相关，而LpA-I/A-II的功能与LCAT活性无关;（ii）LpA-I与LpA-I/A-II协同诱导一系列细胞外事件; LpA-I对排泄的FC进行LCAT介导的酯化，随后CE转移至LpA-I/A-II。这些机制可能是重要的净胆固醇流出的巨噬细胞泡沫细胞在生理状态。(2)We研究了两种含apoA-I的脂蛋白：含apoA-I但不含apoA-II的脂蛋白（LpA-I）和含apoA-I和apoA-II的脂蛋白（LpA-I/A-II）在餐后的变化。这些脂蛋白是从100名男性和111名女性在食用黄油后0，4和6小时分离的。在LPA-I中，除甘油三酯外，所有脂质的水平在4和6小时的妇女中增加。在男性中，所有脂质仅在4小时增加，apoA-I水平仅在女性中在6小时增加。在LpA-I/A-II中，所有脂质的水平在4小时增加，只有磷脂（PL）在6小时增加。在男性中，游离胆固醇和PL在4小时和6小时升高，apoA-I和apoA-II水平仅在男性中在4小时和6小时升高。这些结果表明，餐后的变化是与性别有关的，这些可能与不同的发病率动脉粥样硬化性心血管疾病。少

(1). Two species of lipoprotein containing apoA-I, one containing only apoa-l(LpA-I), and the other containing apoA-I and apoA-II(LpA-I/A-II), were tested for their effects on macrophage fawn cells. Rat macrophages were converted to foam cells by incubation with radiolabelled acetylated LDL. Incubation with LpA-I or LpA-I/A-II decreased the cellular cholesterol esters(CE)mass. However, the free cholesterol(FC)mass was only reduced by LPA-I. All the radioactivity excreted into the medium was associated with LpA-I or LpA-I/A-II ; 39 % of the excreted radioactivity was esteritied in LpA-I and 10 % in LpA-I/A-II. Upon complete inactivation of lecithin : cholesterol acyltransferase(LCAT)activity with dithiobisnitrobenzoic acid, the cholesterol reducing capacity of LpA-I was weakened significantly. However, the CE mass reducing capacity of LpA-I/A-II was not affected. When LpA-I and LpA-I/A-Il were combined, the cholesterol reducing capacity of the mixture was similar to that of LpA-I alone. … More However, LpA-I re-isolated from the medium showed a lower esterification rate than did the re-isolated LpA-I/A-II, thereby indicating that the cholesterol esterified in LpA-I was transferred to LpA-I/A-II. These results suggest that(i)the function of LpA-I is closely linked to the LCAT activity while that of LpA-I/A-II is not, and(ii)LpA-I in concert with LpA-I/A-II induces a series of extracellular events ; LCAT-mediated estefification of excreted FC by LpA-I and a subsequent CE transfer to LpA-I/A-II. These mechanisms might be important for net cholesterol efflux from macrophage foam cells in physiological states.(2)We investigated the postprandial changes of two species of lipoproteins containing apoA-I : lipoprotein containing apoA-I but no apoA-II(LpA-I), and lipoprotein containing apoA-I and apoA-II(LpA-I/A-II). These lipoproteins were isolated from 10men and 11women at 0, 4 and 6 hr after eating butter. In LPA-I, the levels of all lipids except triglyceride were increased at 4 and 6 hr in the women. In the men, all lipids were increased only at 4 hr. The increase of apoA-I level was found at 6 hr only in the women. In LpA-I/A-II, the levels of all lipids were increased at 4 hr and only phospholipid(PL)was increased at 6 hr in the women. In the men, free cholesterol and PL were increased at 4 and 6 hr. The increases of apoA-I and apoA-II levels were found at 4 and 6 hr only in the men. These results suggest that the postprandial changes are gender-related and these may relate to the different incidence of atheroscierotic cardiovascular disorders. Less