Cholesterol Journal Articles

Record 501 to 520

Acyl-coenzyme A:cholesterol acyltransferase
Chang, T. Y., C. C. Chang, et al. (1997), Annu Rev Biochem 66: 613-38.
Abstract: Due to its presumed role in regulating cellular cholesterol homeostasis, and in various pathophysiological conditions, acyl-coenzyme A:cholesterol acyltransferase (ACAT) has attracted much attention. Cloning the ACAT gene provides the necessary tool to advance molecular studies of this enzyme. The topics reviewed in this chapter include the pathophysiological roles of ACAT, the biochemistry and molecular biology of the ACAT protein and the ACAT gene, and the mode of regulation by sterol or nonsterol agents in mammalian cells. In addition, we present a working model linking the presumed allosteric property of ACAT with cholesterol trafficking into and out of the endoplasmic reticulum.

Acyl-coenzyme A:cholesterol acyltransferase inhibition ameliorates proteinuria, hyperlipidemia, lecithin-cholesterol acyltransferase, SRB-1, and low-denisty lipoprotein receptor deficiencies in nephrotic syndrome
Vaziri, N. D. and K. H. Liang (2004), Circulation 110(4): 419-25.
Abstract: BACKGROUND: Nephrotic syndrome (NS) is associated with hyperlipidemia, altered lipid regulatory enzymes and receptors, and increased risk of progressive renal and cardiovascular diseases. Acyl-coenzyme A:cholesterol acyltransferase (ACAT) catalyzes intracellular esterification of cholesterol and plays an important role in production of apolipoprotein B-containing lipoproteins, regulation of cholesterol-responsive proteins, and formation of foam cells. Because hepatic ACAT-2 is markedly upregulated in NS, we tested the hypothesis that inhibition of ACAT may improve cholesterol metabolism in NS. METHODS AND RESULTS: Rats with puromycin-induced NS were treated with either the ACAT inhibitor CI-976 or placebo for 2 weeks. Normal rats served as controls. Plasma lipids, renal function, and key lipid regulatory factors were measured. Untreated NS rats showed heavy proteinuria; hypoalbuminemia; elevated plasma cholesterol, triglyceride, LDL, VLDL, and total cholesterol-to-HDL cholesterol ratio; increased hepatic ACAT activity, ACAT-2 mRNA, and ACAT-2 protein; and reduced LDL receptor, HDL receptor, otherwise known as scavenger receptor B-1 (SRB-1) and plasma lecithin-cholesterol acyltransferase (LCAT). ACAT inhibitor reduced plasma cholesterol and triglycerides, normalized total cholesterol-to-HDL cholesterol ratio, and lowered hepatic ACAT activity without changing ACAT-2 mRNA or protein. This was accompanied by near normalizations of plasma LCAT, hepatic SRB-1, and LDL receptor and a significant amelioration of proteinuria and hypoalbuminemia. CONCLUSIONS: Pharmacological inhibition of ACAT reverses NS-induced LDL receptor, HDL receptor, and LCAT deficiencies; improves plasma lipid profile; and ameliorates proteinuria in nephrotic animals. Further studies are needed to explore the effect of ACAT inhibition in nephrotic humans.

Acyl-coenzyme A:cholesterol acyltransferase inhibitor, avasimibe, stimulates bile acid synthesis and cholesterol 7alpha-hydroxylase in cultured rat hepatocytes and in vivo in the rat
Post, S. M., J. P. Zoeteweij, et al. (1999), Hepatology 30(2): 491-500.
Abstract: Acyl-coenzyme A:cholesterol acyltransferase (ACAT) inhibitors are currently in clinical development as potential lipid-lowering and antiatherosclerotic agents. We investigated the effect of avasimibe (Cl- 1011), a novel ACAT inhibitor, on bile acid synthesis and cholesterol 7alpha-hydroxylase in cultured rat hepatocytes and rats fed different diets. Avasimibe dose-dependently decreased ACAT activity in rat hepatocytes in the presence and absence of beta-migrating very low-density lipoproteins (betaVLDL) (by 93% and 75% at 10 micromol/L) and reduced intracellular storage of cholesteryl esters. Avasimibe (3 micromol/L) increased bile acid synthesis (2.9-fold) after preincubation with betaVLDL and cholesterol 7alpha-hydroxylase activity (1.7- and 2.6-fold, with or without betaVLDL), the latter paralleled by a similar induction of its messenger RNA (mRNA). Hepatocytes treated with avasimibe showed a shift from storage and secretion of cholesteryl esters to conversion of cholesterol into bile acids. In rats fed diets containing different amounts of cholesterol and cholate, avasimibe reduced plasma cholesterol (by 52% to 71%) and triglyceride levels (by 28% to 62%). Avasimibe did not further increase cholesterol 7alpha-hydroxylase activity and mRNA in cholesterol-fed rats, but prevented down-regulation by cholate. Avasimibe did not affect sterol 27-hydroxylase and oxysterol 7alpha-hydroxylase, 2 enzymes in the alternative pathway in bile acid synthesis. No increase in the ratio of biliary excreted cholesterol to bile acids was found, indicating that ACAT inhibition does not result in a more lithogenic bile. Avasimibe increases bile acid synthesis in cultured hepatocytes by enhancing the supply of free cholesterol both as substrate and inducer of cholesterol 7alpha-hydroxylase. These effects may partially explain the potent cholesterol-lowering effects of avasimibe in the rat.

Acyl-coenzyme A:cholesterol acyltransferase-2 (ACAT-2) is responsible for elevated intestinal ACAT activity in diabetic rats
Hori, M., M. Satoh, et al. (2004), Arterioscler Thromb Vasc Biol 24(9): 1689-95.
Abstract: OBJECTIVE: Diabetes-induced dyslipidemia is seen in streptozotocin-induced diabetic rats. This is caused, in part, by elevated intestinal acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity. Because two ACAT isozymes (ACAT-1 and ACAT-2) were identified, in the present study we determined which ACAT isozyme was involved in the elevated intestinal ACAT activity in diabetic rats. METHODS AND RESULTS: We cloned a full-length cDNA of rat ACAT-2. Its overexpression in ACAT-deficient AC29 cells demonstrated that the ACAT activity is derived from the cloned cDNA, and a 45-kDa protein of rat ACAT-2 cross-reacts with an anti-human ACAT-2 antibody. The tissue distribution of rat ACAT-2 mRNA revealed its restricted expression to liver and small intestine. Immunohistochemical analyses using an anti-human ACAT-2 antibody demonstrated that ACAT-2 is localized in villus-crypt axis of rat small intestine. The intestinal ACAT activity in diabetic rats was significantly immunodepleted by an anti-ACAT-2 antibody but not by an anti-ACAT-1 antibody. Finally, intestinal ACAT-2 in diabetic rats significantly increased at both protein and mRNA levels as compared with that in control rats. CONCLUSIONS: Our data demonstrate that ACAT-2 isozyme is responsible for the increased intestinal ACAT activity of diabetic rats, suggesting an important role of ACAT-2 for dyslipidemia in diabetic patients. Diabetic rats exhibit dyslipidemia caused, in part, by elevated intestinal acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity. We determined which ACAT isozyme (ACAT-1 or ACAT-2) was involved in the elevated intestinal ACAT activity in diabetic rats. We demonstrated an important role of ACAT-2, implicating its involvement in dyslipidemia in diabetic patients.

Acyl-coenzymeA (CoA):cholesterol acyltransferase inhibition in rat and human aortic smooth muscle cells is nontoxic and retards foam cell formation
Rong, J. X., J. Kusunoki, et al. (2005), Arterioscler Thromb Vasc Biol 25(1): 122-7.
Abstract: OBJECTIVE: Studies in vitro and in vivo of macrophage foam cells have shown evidence of cytotoxicity after acyl-CoA:cholesterol acyltransferase (ACAT) inhibition. Foam cells of smooth muscle origin are also found in human and animal atherosclerotic lesions. METHODS AND RESULTS: To study whether cytotoxicity from ACAT inhibition is independent of cell type, we first established a protocol to conveniently induce aortic smooth muscle foam cell formation using cholesterol-cyclodextrin complexes (CCC). Rat aortic smooth muscle cells (ASMCs) treated for 48 hours with CCC (20 microg/mL) became foam cells by morphological (oil-red-O staining) and biochemical (approximately 1200% and approximately 180% increase in cellular esterified and free cholesterol, respectively) criteria. ACAT activity increased 500% (P<0.01 versus untreated). Similar results were obtained in human ASMC, but ACAT activity increased to an even greater extent (3200%; P<0.01 versus untreated). Western blots indicated that CCC treatment increased human (to 380+/-20% of untreated, P<0.001), but not rat, ACAT protein expression. ACAT inhibition by Fujirebio compound F1394 suppressed CCC-induced foam cell formation in rat and human ASMC, but, notably, did not induce significant cytotoxicity. CONCLUSIONS: ASMC might be more resistant to FC-induced adverse effects than are macrophages.

Adaptation of a cholesterol deficient human T cell line to growth with lanosterol
Buttke, T. M. and S. Van Cleave (1994), Biochem Biophys Res Commun 200(1): 206-12.
Abstract: A3.01 is a human T cell line previously shown to be defective in cholesterol biosynthesis. Following passage into serum-free medium, A3.01 cells displayed a gradual decline in growth rate which correlated with a depletion of cellular cholesterol content and an accumulation of lanosterol and 24,25-dihydrolanosterol. At the point when cholesterol became undetectable, the growth rate of serum-deprived cells was only one-tenth of the rate observed for serum-supplemented cells. The addition of low density lipoproteins (LDL) restored cellular cholesterol content and resulted in a 7-fold higher growth rate, confirming that cholesterol-deprivation was responsible for the slower growth in the absence of serum. Following prolonged culture in serum-free medium, A3.01 cells underwent a phenotypic change such that the cells achieved a growth rate which was approximately 65% of either LDL-supplemented or cholesterol-proficient cells. This apparent adaptation was not attributable to changes in either fatty acid or sterol composition. These results demonstrate that while cholesterol is preferred, this lymphoid cell line can adapt to the use of lanosterol to satisfy its membrane sterol requirement.

Adaptation of an enzymatic kit for the assay of cholesterol in tissue lipid extracts
Wang, W. and A. Gustafson (1993), Acta Chem Scand 47(8): 846-8.
Abstract: In the assay for total cholesterol in lipid extracts by enzymatic methods, it was found necessary to redissolve the lipid prior to the reagent addition. Isopropyl alcohol was found to be best at promoting the colorimetric reaction. As little as 1.45 micrograms free cholesterol and 1.8 micrograms esterified cholesterol could be determined after 15 min incubation with the isopropyl alcohol-reagent. Using a formula for the correction of pigment absorbance, it was also possible to apply the enzymatic kit method to red blood cell lipid extracts.

Adaptation of cholesterol absorption after proximal resection of porcine small intestine
Pakarinen, M., T. A. Miettinen, et al. (1996), J Lipid Res 37(8): 1766-75.
Abstract: Cholesterol absorption occurs primarily in the upper small intestine. Our aim was to assess absorption of cholesterol during ileal adaptation after proximal small intestinal resection. In vivo absorption and elimination of cholesterol, plasma cholesterol, cholesterol precursors, and plant sterols were related to intestinal morphology and transit 4 (n = 5), 8 (n = 5), and 14 (n = 5) weeks after a 75% proximal resection of porcine small intestine, and compared to preoperative (n = 5) and transected (n = 5) control animals. Fractional cholesterol absorption, the daily amount of cholesterol absorbed, plasma cholesterol, and plant sterol to cholesterol proportions were significantly (P < 0.05 or less) decreased, whereas fecal loss of cholesterol as neutral steroids, less so as bile acids, plasma cholesterol precursor proportions, and ileal mass and villus height were significantly increased (P < 0.05 or less) after 8 weeks of the resection. Cholesterol absorption efficiency, decreased by the resection, was gradually increased from 5.4 +/- 2.2 to 26.9 +/- 3.9% during the 14 postoperative weeks (P < 0.0001) simultaneously with a 46% increase in villus height compared with transection (P < 0.0001), but absorption remained still below control levels (80.4 +/- 2.5%, P < 0.0001). In resected and control animals, villus height correlated positively with cholesterol absorption efficiency (r = 0.85, P < 0.0001; r = 0.76, P = 0.01) and plasma plant sterol proportions (r = 0.94-0.95, P < 0.0001; r = 0.78-0.85, P < 0.008), respectively. In conclusion, after massive proximal small bowel resection, adaptation of intestinal cholesterol absorption efficiency occurs in the distal ileum closely parlleling villus hypertrophy.

Addition of arginine but not glycine to lysine plus methionine-enriched diets modulates serum cholesterol and liver phospholipids in rabbits
Giroux, I., E. M. Kurowska, et al. (1999), J Nutr 129(10): 1807-13.
Abstract: Previous experiments from our laboratory showed that in rabbits fed an amino acid diet corresponding to 30% casein, enrichment of the diet with L-lysine and L-methionine caused a marked increase in serum total and LDL cholesterol levels as well as a substantial body weight loss. Both effects were partially prevented by supplementation with L-arginine. The present studies were designed to extend this earlier observation by assessing the role of different dietary amino acids in modulation of cholesterolemic responses and body weights. In the first experiment, the original lysine and methionine-enriched diet was supplemented with glycine in an attempt to modify methionine metabolism, and thus to reduce body weight loss. In addition, the mechanism of action of lysine and methionine was investigated by quantitation of major liver phospholipids. The results showed that glycine addition had no effect on weight loss or hypercholesterolemia, nor did it alter plasma levels of homocyst(e)ine, an intermediate in methionine metabolism. However, enrichment of the diet with lysine and methionine (with or without glycine) significantly increased liver levels of phosphatidylcholine and the ratio of phosphatidylcholine to phosphatidylethanolamine, apparently through increased enzymatic conversion. These changes were consistent with higher lipoprotein levels and thus may explain the hypercholesterolemia. A second experiment showed that similar effects on body weights and serum cholesterol could be obtained by adding lysine and methionine to a diet containing amino acids equivalent to only 15% casein, or 15% intact casein. This approach is more physiologic and also reduces the expense of experiments designed to study the effects of lysine and methionine in more detail.

Addition of dimethylsulphoxide to methyl-tert-butyl ether and ethyl propionate increases cholesterol dissolving capacity and cholesterol gall stone dissolution in vitro
Bergman, J. J., A. K. Groen, et al. (1994), Gut 35(11): 1653-8.
Abstract: There is a discrepancy between in vitro cholesterol dissolving efficacy of methyl-tert-butyl ether (MTBE) and ethyl propionate and cholesterol gall stone dissolution in vivo. This study investigated whether the presence of bile changes the cholesterol dissolving capacity of MTBE and ethyl propionate. The addition of dimethylsulphoxide to MTBE or ethyl propionate was also studied to discover if it improves the dissolving capacity for cholesterol gall stones. The presence of bile caused a 25% decrease in cholesterol dissolving capacity of both MTBE and ethyl propionate (p < 0.0001). This inhibitory effect of bile could be overcome by the addition of dimethyl-sulphoxide: dimethylsulphoxide caused an increase in cholesterol dissolving capacity of MTBE and ethyl propionate, the increase depending on the dimethyl-sulphoxide/bile ratio in the mixture. Mean dissolution time of weight, size, and patient matched cholesterol gall stones was 220 minutes in MTBE and 130 minutes in MTBE/dimethylsulphoxide (p < 0.0001). No stones dissolved completely in ethyl propionate or ethyl propionate/dimethyl-sulphoxide within 300 minutes. In conclusion, MTBE/dimethylsulphoxide is a more potent dissolving agent for cholesterol gall stones than MTBE, giving a 40% reduction in dissolution time. Addition of dimethylsulphoxide to ethyl propionate does not result in faster stone dissolution. MTBE and MTBE/dimethylsulphoxide are far superior to ethyl propionate as solvents for cholesterol gall stones.

Addition of guar gum and soy protein increases the efficacy of the American Heart Association (AHA) step I cholesterol-lowering diet without reducing high density lipoprotein cholesterol levels in non-human primates
Wilson, T. A., S. R. Behr, et al. (1998), J Nutr 128(9): 1429-33.
Abstract: The aim of this study was to determine whether the addition of soy protein and guar gum to the American Heart Association (AHA) Step I diet would increase its efficacy compared with the typical "Average American Diet" (AAD) in a non-human primate model. Twenty adult female cynomolgus monkeys (Macaca fascicularis) were fed one of three diets for 6 wk. The AAD contained 36% energy from fat; the standard Step I diet contained 30% energy from fat; and the modified AHA Step I diet contained 30% energy from fat with the addition of soy protein isolate (10% of total energy) and guar gum (5.8 g/d). Plasma samples were collected from food-deprived monkeys at 4, 5 and 6 wk of dietary treatment for analyses of plasma total cholesterol (TC), lipoprotein cholesterol and triacylglycerol (TAG) concentrations. Plasma TC, LDL-C, HDL-C and TAG concentrations were not significantly different in wk 4, 5 and 6 within any of the diet periods; thus the three measurements were averaged. After 6 wk of dietary treatment, monkeys fed the standard Step I diet had lower plasma TC (-19%) (P < 0.05) and LDL cholesterol (LDL-C) (-24%) (P < 0.09) than when they were fed the AAD, with no effect on HDL cholesterol (HDL-C), the lipoprotein cholesterol profile or TAG. Beyond the effect of the standard Step I diet, the modified AHA Step I diet further reduced plasma TC and LDL-C (-24% and -40%) (P < 0. 05) and the TC/HDL-C and LDL-C/HDL-C ratios (-37% and -52%) (P < 0. 05) with no significant changes in plasma HDL-C or TAG. The primary conclusions of this study are that the efficacy of the AHA Step I cholesterol-lowering diet can be increased with the addition of soy protein and guar gum and provide a more favorable lipoprotein cholesterol profile. Whether the cholesterol-lowering effect is the result of soy protein or guar gum or a synergistic effect of both remains to be determined.

Addition of N-acetylcysteine to aqueous model bile systems accelerates dissolution of cholesterol gallstones
Niu, N. and B. F. Smith (1990), Gastroenterology 98(2): 454-63.
Abstract: The organic matrix of cholesterol gallstones contains a macromolecular complex of mucin and bilirubin that may inhibit stone dissolution by limiting contact of desaturated bile with crystalline cholesterol. The goal of this study was to determine if the mucolytic agent N-acetylcysteine could accelerate gallstone dissolution in vitro. Paired gallstones were dissolved in either pure taurocholate (140 mM) or ursodeoxycholate (100 mM), or in bovine bile supplemented with either taurocholate or ursodeoxycholate to achieve the same respective bile-salt concentrations. N-acetylcysteine was added to 1 stone from each pair at a concentration of 500 mM in pure bile salts and 100 mM in supplemented bile. Gallstones dissolved significantly faster in bovine bile supplemented with taurocholate or ursodeoxycholate than in pure solutions of the respective bile salts (n = 30, p less than 0.001). N-acetylcysteine significantly accelerated gallstone dissolution in pure solutions of bile acids (n = 30, p less than 0.001 for each) and in supplemented bovine biles (n = 30, p less than 0.001). N-acetylcysteine also significantly increased the frequency of complete gallstone dissolution in taurocholate-supplemented (66.6% vs. 40.0%) and ursodeoxycholate-supplemented (76.6% vs. 50.0%) bile. These results indicate that the mucolytic agent N-acetylcysteine significantly accelerates in vitro gallstone dissolution. We speculate that adjuvant therapy with an appropriate mucolytic agent may potentially increase the efficacy of clinical gallstone dissolution.

Additional effects of statins independent of the cholesterol-lowering as yet not shown to be clinically relevant
Visseren, F. L., P. J. Lansberg, et al. (2000), Ned Tijdschr Geneeskd 144(17): 822-3.

Additive effect of plant sterol-ester margarine and cerivastatin in lowering low-density lipoprotein cholesterol in primary hypercholesterolemia
Simons, L. A. (2002), Am J Cardiol 90(7): 737-40.
Abstract: The objective of this study was to evaluate whether plant sterol-ester margarine has an additive or interactive effect on low-density lipoprotein (LDL) cholesterol reduction when ingested in combination with a statin drug. This was a multicenter, randomized, double-blind study with 4 parallel treatment arms in a balanced 2 x 2 factorial design. The 4 daily treatment options were: (1) placebo plus regular margarine 25 g (n = 38); (2) placebo plus sterol-ester margarine 25 g (2 g of plant sterol) (n = 39); (3) cerivastatin 400 microg plus regular margarine 25 g (n = 38); and (4) cerivastatin 400 microg plus sterol-ester margarine 25 g (n = 37). The study was conducted in men and women with primary hypercholesterolemia with baseline LDL cholesterol >/=97 mg/dl (mean 206). The primary efficacy parameter was the percent change in LDL cholesterol between baseline and at the end of 4 weeks' treatment. Cerivastatin (vs placebo) reduced LDL cholesterol by 32% (95% confidence intervals 28% to 36%, p <0.0001) and sterol-ester margarine (vs regular margarine) by 8% (95% confidence interval 4% to 12%, p <0.0001). The effect of sterol-ester margarine and cerivastatin together was additive (39% reduction in LDL cholesterol), but there was no significant interactive effect between sterol-ester margarine and cerivastatin (p = 0.29). The treatments were generally well tolerated with no major differences in adverse events between groups. In subjects with primary hypercholesterolemia, statin and sterol-ester margarine used together produce a purely additive effect on LDL cholesterol reduction. The addition of sterol-ester margarine to statin therapy offers LDL cholesterol reduction equivalent to doubling the dose of statin.

Additive effect of steroids and cholesterol on the liposomal transfection of the breast cancer cell line T-47D
Koster, F., D. Finas, et al. (2004), Int J Mol Med 14(4): 769-72.
Abstract: The efficiency of gene transfer is many times higher in viral than in liposomal transfection. One reason for this is an insufficient intracellular transport of the exogenous DNA into the nucleus in lipofection. Using liposomal transfection techniques for gene therapy is safer than viral approaches, so it would be of great importance to find solutions for their enhancement. We found a 4.51-fold increase in liposomal transfection of T-47D breast cancer cells by the addition of progesterone and a 2.81-fold increase by the addition of cholesterol. The transfection efficiency was measured as the activity of the delivered reporter gene luciferase. The addition of progesterone and cholesterol in combination led to a further enhancement of the transfection efficiency up to 13.72-fold. This additive effect could also be seen when we combined cholesterol with other steroids, but not by the combination of different steroids. All of these steroids alone had also the potential to increase liposomal transfection. Therefore we suggest that steroids and cholesterol enhance liposomal transfection by different mechanisms. Both substances have been shown to shift the exogenous DNA from the cytosol to the nucleus. Steroids normally act through intracellular steroid receptors, which migrate into the nucleus upon activation. The transfected DNA might be co-transported to the nucleus together with the migration of the activated steroid receptors. Even if cholesterol causes also an intracellular shift of DNA to the nucleus, its impact on the fluidity of cellular membranes or on the stability of lipoplexes in serum containing media could be mainly responsible for its effect. If the steroid enhanced liposomal transfection is dependent on the presence of steroid receptors, a specifically-enhanced gene delivery for a subgroup of gynecological tumours expressing high levels of steroid receptors could be possible.

Additive effects of Simvastatin beyond its effects on LDL cholesterol in hypertensive type 2 diabetic patients
Tonolo, G., M. G. Melis, et al. (2000), Eur J Clin Invest 30(11): 980-7.
Abstract: BACKGROUND: Experimental evidence indicates that statins might have direct vascular effects independently from low-density lipoprotein (LDL) cholesterol reduction and we reported that the reduction in urinary albumin excretion rate during Simvastatin treatment in type 2 diabetic patients was not correlated with LDL-cholesterol decrease. However in humans there are no data regarding possible additional effects of Simvastatin on blood pressure and urinary albumin excretion beyond its capacity to lower serum cholesterol. PATIENTS AND METHODS: Twenty-six microalbuminuric hypertensive type 2 diabetic patients (diastolic blood pressure - after four months wash-out from the previous antihypertensive therapy - consistently > 90 and < 100 mmHg; plasma LDL-cholesterol > 3.9 and < 6.5 mmol L-1) were enrolled in the study. In random order, these patients received Simvastatin (20 mg day-1) or Cholestyramine (6 g three times a day) for a period of 10 months and after three months of wash-out (cross-over) the sequence was reversed for an additional 10 months. Blood pressure, lipid parameters, glycated haemoglobin and urinary albumin excretion were measured during the study. Additionally, in eight patients, urinary glycosaminoglycan excretion (GAG) was also measured during the study. RESULTS: Simvastatin and Cholestyramine were equally effective in reducing total and LDL cholesterol. Only during Simvastatin treatment a significant reduction in diastolic blood pressure and both 24 h urinary albumin and GAG excretion rates were observed, while no significant changes were seen with Cholestyramine treatment. CONCLUSIONS: Our results clearly show for the first time that the reduction of blood pressure, together with 24 h urinary albumin excretion rate - two established cardiovascular risk factors, obtained during Simvastatin therapy in hypertensive type 2 diabetic patients - is in large part independent from the reduction of LDL Cholesterol.

Addressing cardiovascular risk beyond low-density lipoprotein cholesterol: the high-density lipoprotein cholesterol story
Meagher, E. A. (2004), Curr Cardiol Rep 6(6): 457-63.
Abstract: A large body of evidence from numerous, well-controlled, randomized trials demonstrates that treatment with statins reduce morbidity and mortality from cardiovascular disease (CVD). Although these observations are important and have resulted in the adoption of standard of care approaches to the management of CVD risk, they do not tell the whole story. When reviewing these landmark trials it is clear that on average two thirds of events are not prevented. This leads to the evaluation of risk beyond low-density lipoprotein cholesterol. This review focuses on the association of low high-density lipoprotein (HDL) cholesterol and increased CVD risk, the published trials that study the effect of raising HDL cholesterol on CVD outcomes, and the novel approaches toward HDL cholesterol raising that are on the horizon.

Adenine for guanine substitution -78 base pairs 5' to the apolipoprotein (APO) A-I gene: relation with high density lipoprotein cholesterol and APO A-I concentrations
Civeira, F., M. Pocovi, et al. (1993), Clin Genet 44(6): 307-12.
Abstract: A common mutation, adenine (A) for guanidine (G) substitution (G/A) has been located -78 bp 5' to the apo A-I gene. This region has been shown to be involved in the transcriptional regulation of the apo A-I gene. Previous studies have shown that this mutation is associated with altered high density lipoprotein cholesterol (HDL-C) levels, although these findings have not been consistent. We have studied the frequency of this mutation in 125 subjects (60 males and 65 females) selected because they had HDL-C levels below the 25th (low HDL) or above the 75th (high HDL) percentile of the population distribution. The presence of the mutation was detected by Msp I digestion of a 259 bp fragment of PCR amplified DNA. The allele frequency was similar in both groups (0.20 for the lowest HDL group and 0.28 for the highest HDL group, p > 0.05), although a non-significant trend was observed in a higher frequency of the A/A genotype in the highest HDL females (17.5%) vs only 6.7% in the lowest HDL female group. In conclusion, in this population the G/A mutation was not significantly associated with HDL-C or apo A-I plasma levels.

Adenocarcinoma confined to a cholesterol polyp of the gallbladder
Shimada, K., J. Yamamoto, et al. (1999), Am J Gastroenterol 94(9): 2568-9.

Adenosine A2A receptor occupancy stimulates expression of proteins involved in reverse cholesterol transport and inhibits foam cell formation in macrophages
Reiss, A. B., M. M. Rahman, et al. (2004), J Leukoc Biol 76(3): 727-34.
Abstract: Transport of cholesterol out of macrophages is critical for prevention of foam cell formation, the first step in the pathogenesis of atherosclerosis. Proteins involved in this process include cholesterol 27-hydroxylase and adenosine 5'-triphosphate-binding cassette transporter A1 (ABCA1). Proinflammatory cytokines and immune complexes (IC) down-regulate cholesterol 27-hydroxylase and impede cholesterol efflux from macrophages, leading to foam cell formation. Prior studies have suggested occupancy of the anti-inflammatory adenosine A2A receptor (A2AR) minimizes early atherosclerotic changes in arteries following injury. We therefore asked whether A2AR occupancy affects macrophage foam cell formation in response to IC and the cytokine interferon-gamma. We found that the selective A2AR agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamido-adenosine (CGS-21680) inhibited foam cell formation in stimulated THP-1 human macrophages, and the effects of CGS-21680 were reversed by the selective A2AR antagonist 4-(2-7-amino-2-(2-furyl) 1, 2, 4triazolo2,3-a 1, 3, 5triazin-5-ylaminoethyl)phenol. In confirmation of the role of A2AR in prevention of foam cell formation, CGS-21680 also inhibited foam cell formation in cultured murine peritoneal macrophages but did not affect foam cell formation in A2AR-deficient mice. Agents that increase foam cell formation also down-regulate cholesterol 27-hydroxylase and ABCA1 expression. Therefore, we determined the effect of A2AR occupancy on expression of these reverse cholesterol transport (RCT) proteins and found that A2AR occupancy stimulates expression of message for both proteins. These results indicate that one mechanism for the antiatherogenic effects of adenosine is stimulation of the expression of proteins involved in RCT. These findings suggest a novel approach to the development of agents that prevent progression of atherosclerosis.

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