Plasma cholesteryl ester transfer protein (CETP) facilitates the transfer of cholesteryl ester (CE) from HDL to apolipoprotein B-containing lipoproteins and therefore is a key protein in the reverse cholesterol transport system. The importance of plasma CETP in lipoprotein metabolism has been highlighted by the discovery of CETP-deficient subjects with a marked hyper-HDL-cholesterolemia. The deficiency of CETP causes various abnormalities in the concentration, composition, and functions of high density and low density lipoproteins. The current review will focus on some of the recent knowledge on CETP with special reference to the biochemical and molecular biological aspects of CETP. Furthermore, detailed information will be presented regarding the lipoprotein abnormalities and molecular basis of CETP deficiency. J Atheroscler Thromb, 1996 ; 3 : 1-11.

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We have identified two apolipoprotein (apo) A-I variants using isoelectric focusing gel electrophoresis : apo A-I Kaho which has a relative charge of +1 compared to normal apo A-I₄, and apo A-I Nanakuma2 which has a relative charge of -1. Sequence analysis of PCR-amplified DNA from the proband of apo A-I Kaho revealed a single substitution of aspartic acid (GAC) for valine (GTC) at residue 51. Sequence analysis of PCR-amplified DNA from the proband of apo A-I Nanakuma2 revealed a three-base (AAG or AGA) deletion between bases 186 and 193 from the 5' end of exon 4 that leads to deletion of Lys 106 or 107. This mutation may be the same as that of apo A-I Marburg or A-I Munster-2 reported by Rall et al. (Rall SC Jr, Weisgraber KH, Mahley RW, Ogawa Y, Fielding CJ, Utermann G, Haas J, Steinmetz A, Menzel HJ, and Assmann G, J Biol Chem, 259 : 10063-10070, 1984). Because of its unique sequence between 185 and 193 from the 5' end of exon 4 of apo A-I gene, we could not define whether AAG or AGA is deleted by DNA sequencing. J Atheroscler Thromb, 1996 ; 3 : 12-16.

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We examined the lipoprotein lipase (LPL) gene by single strand conformation polymorphism (SSCP) and by restriction fragment length polymorphism (RFLP) analysis in 106 patients with hypertriglyceridemia to screen for novel mutations and to study the contribution of LPL genetic defects in hypertriglyceridemia. We found a single incidence of a homozygous novel nonsense mutation (²¹⁶G→A ;^-14Tryptophan→stop codon) in exon 1 and 6 cases heterozygous for a single transition (C→T) at six by upstream from splicing acceptor site of intron 3. These mutations were not found in 105 normolipidemic controls. The proband homozygous for the nonsense mutation in exon 1, a 74 year old woman, had mild hyperchylomicronemia and her post-heparin plasma showed no LPL protein. However, four heterozygous among family members did not demonstrate hypertriglyceridemia. The frequency of heterozygosity for the C→T transition in intron 3 was significantly different from that in normolipidemic controls. Therefore, it was suggested that the mutation is involved in hypertriglyceridemia. All of the heterozygotes were men with 4 patients having impaired glucose tolerance or diabetes mellitus. These observations suggest that this polymorphism in intron 3 combined with other as yet undefined factors may be related to hypertriglyceridemia. J Atheroscler Thromb, 1996 ; 3 : 17- 24.

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Vitronectin is one of the major extracellular matrix proteins that accumulates in atherosclerotic lesions. A monoclonal antibody (EMR1a/212D) specifically stained the extracellular regions in thickened intima which colocalized well with lipid deposition. The antigenic glycoprotein with a molecular weight of 66KDa was revealed to be rabbit vitronectin. When homogenates of WHHL rabbit atheroma were subjected to immunoblot analysis using EMR1a/212D, four molecules with molecular weight 66, 56, 50 and 47KDa were detected. To confirm whether these smaller immunopositive bands were derived from mature vitronectin, another monoclonal antibody (EMR1b/244H) recognizing the polypeptide region of vitronectin was prepared. All four molecules were detected by EMR1b/244H as well as by EMR1a/212D. Two smaller vitronectins (56KDa and 50KDa) were found in atherosclerotic lesions and increased markedly during the development of atherosclerosis. On the other hand, the vitronectin detected in normal rabbit aorta was mainly of the mature type, while 56KDa and 47KDa forms were not detected. The total amount of the four vitronectins in atherosclerotic lesions was 38.5±5.0 ng/mg wet weight tissue, a value approximately 9.5 fold higher than that found in normal aorta. In conclusion, we found massive accumulation of these vitronectins concomitant with atherosclerotic development in rabbit aorta. J Atheroscler Thromb, 1996 ; 3 : 25-31.

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Protease inhibitors such as aprotinin and urinastatin inhibited vascular endothelial cell injury induced by PMA-stimulated leukocytes, although their inhibitors did not suppress the production of active oxygen species released from leukocytes. On the other hand, in the presence of pancreas elastase (10, μg/ml), hydrogen peroxide (50, μM) caused severe injury of endothelial cells isolated from the bovine carotid artery (% specific ⁵¹Cr release; % SR=42.9±3.3%), although the % SR elicited by elastase or hydrogen peroxide alone, respectively, was below 1%. Elastase and hydrogen peroxide acted synergistically on the injury of endothelial cells from the bovine carotid artery similarly to that in the endothelial cells isolated from the bovine coronary artery and human umbilical vein. Furthermore, elastase derived from both pancreas and leukocyte induced this synergistic action on endothelial cell injury. To clarify the mechanism of vascular endothelial cell injury induced by the combination of elastase and hydrogen peroxide, we examined the effects of various radical scavengers and protease inhibitors. Deferoxamine mesylate completely inhibited the endothelial cell injury, while protease inhibitors such as antitrypsin and macroglobulin had a protective effect. Pretreatment of endothelial cells with deferoxamine mesylate also protected against this cytotoxicity. These findings suggested that the synergistic effect of elastase and hydrogen peroxide on the endothelial cell injury is due to the production of hydroxylradical in the endothelium and that this synergistic action might be partially involved in the endothelial cell injury induced by activated leukocytes. J Atheroscler Thromb, 1996 ; 3 : 32-38.

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We investigated coronary segmental responses to intracoronary acetylcholine (ACh) in 19 patients with hypercholesterolemia and 18 patients with normal cholesterol levels. All patients had atypical chest pain and angiographically normal coronary arteries. After baseline angiography, ACh (3 and 30μg/min) was infused into the left coronary artery, followed by infusion of nitroglycerin. Percent changes in diameter of the proximal, middle, and distal segments of the left coronary arteries were measured by quantitative angiography. In the normocholesterolemic group, 3μg/min of ACh produced significant coronary vasodilation in the distal segments (+8.2±2.6%, p<0.005), while 30 μg/min did not cause any changes. In the hypercholesterolemic group, 30μg/min of ACh caused significant coronary vasoconstriction in the middle and distal segments (-7.2±1.9% and -6.2±1.9%, p<0.001 and p<0.01, respectively), while 3μg/min caused no changes. In each group, vasodilator responses to nitroglycerin in the middle and distal segments were significantly greater than those in the proximal segments (p<0.001). Our results suggest that impaired endothelial function may be evaluated more effectively in the distal coronary segments in patients in the early stage of epicardial coronary atherosclerosis attributable to hypercholesterolemia. J Atheroscler Thromb, 1996 ; 3 : 39-44.

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We investigated the relationships of plasma sex hormones (free testosterone ; free T, estradiol ; E₂, dehydroepiandrosterone-sulfate ; DHEA-S) and sex hormone-binding globulin (SHBG) levels to lipid and glucose metabolism cross-sectionally in 212 apparently healthy men aged from 18 to 59 years. A multiple linear regression analysis for lipid and glucose parameters with age, body mass index (BMI), percent body fat (%fat), waist to hip ratio (WHR), estimated maximal oxygen uptake (VO₂max), alcohol and cigarette consumption, sex hormones, and SHBG, respectively, as independent variables, was performed. DHEA-S was indicated as one of the independent predictors of both high density lipoprotein cholesterol (HDL-C), with a positive relation, and of triglyceride and total cholesterol/HDL-C ratio, with a negative relation, while SHBG was one of the predictors of both HDL-C, with a positive relation, and of fasting insulin, with a negative relation. The E2 level was found to be negatively related to both low density lipoprotein cholesterol and fasting blood glucose. These findings thus suggest that the higher levels of SHBG, DHEA-S and E2 within physiological ranges in healthy men may partially help to maintain a desirable profile of the plasma lipid and glucose metabolism. J Atheroscler Thromb, 1996 ; 3 : 45-51.

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Normal and alloxan diabetic rats were kept on a 0.25% cholesterol diet for 12 months and the changes in serum cholesterol levels, and fecal excretion of sterols and bile acids were examined to elucidate the influence of changes in bile acid metabolism on manifestations of hypercholesterolemia and development of atheromatous lesions. Diabetic rats fed the cholesterol diet showed increases in bile acid synthesis and in the cholic acid group/chenodeoxycholic acid group (CA/ CDCA) ratio, and developed significant hypercholesterolemia and atheromatous lesions. In contrast, normal rats showed increased bile acid synthesis but a decreased CA/CDCA ratio after feeding with the cholesterol diet, and developed neither hypercholesterolemia nor atheromatous lesions. Fecal sterol excretion and the cholesterol/sitosterol ratio decreased in diabetic rats. Positive correlations were found between the cumulative serum cholesterol level and the atheromatous lesion area, and between the fecal CA/CDCA ratio and the serum cholesterol level, in the latter of which the correlation was higher in rats on the cholesterol diet than in those on the standard diet. These findings suggest that alteration of bile acid metabolism with increases in cholic acid synthesis and CA/CDCA ratio in diabetic rats enhances cholesterol absorption to produce significant hypercholesterolemia, which in turn leads to development of atheromatous lesions. J Atheroscler Thromb, 1996 ; 3 : 52-58.

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