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Apolipoprotein CI (apoCI) has been suggested to influence HDL metabolism by activation of LCAT and inhibition of HL and CETP. However, the effect of apoCI on scavenger receptor BI (SR-BI)-mediated uptake of HDL-cholesteryl esters (CE), as well as the net effect of apoCI on HDL metabolism in vivo is unknown. Therefore, we evaluated the effect of apoCI on the SR-BI-mediated uptake of HDL-CE in vitro and determined the net effect of apoCI on HDL metabolism in mice. Enrichment of HDL with apoCI dose-dependently decreased the SR-BI-dependent association of [3H]CE-labeled HDL with primary murine hepatocytes, similar to the established SR-BI-inhibitors apoCIII and oxLDL. ApoCI deficiency in mice gene dose-dependently decreased HDL-cholesterol levels. Adenovirus-mediated expression of human apoCI in mice increased HDL levels at a low dose and increased the HDL particle size at higher doses. We conclude that apoCI is a novel inhibitor of SR-BI in vitro and increases HDL levels in vivo. © 2008 Elsevier Inc. All rights reserved.

Personalised, genotype-based nutrition is a concept that links genotyping with specific nutritional advice in order to improve the prevention of nutrition-associated, chronic diseases. This review describes the current scientific basis of the concept and discusses its problems. There is convincing evidence that variant genes may indeed determine the biological response to nutrients. The effects of single-gene variants on risk or risk factor levels of a complex disease are, however, usually small and sometimes inconsistent. Thus, information on the effects of combinations of relevant gene variants appears to be required in order to improve the predictive precision of the genetic information. Furthermore, very few associations between genotype and response have been tested for causality in human intervention studies, and little is known about potential adverse effects of a genotype-derived intervention. These issues need to be addressed before genotyping can become an acceptable method to guide nutritional recommendations. © The Authors 2007.

The influence of the 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors pravastatin and simvastatin on lens cholesterol metabolism was investigated in the rat. Short-term organ culture experiments with explanted lenses from 21-day-old Wistar rats showed that simvastatin was at least 35 times more effective than pravastatin in inhibiting cholesterol synthesis. In vivo the cholesterol content of the rat lens increased linearly with age. Experiments were designed to answer the question whether simvastatin and pravastatin inhibit lens cholesterol synthesis in vivo, which would result in a reduced cholesterol accumulation in the lens with age. Young Wistar rats were weaned at an age of 21 days and had ad libitum access to a chow supplemented with 10-100 mg vastatin kg-1 (drug consumption: 1.5-15 mg vastatin kg-1 body weight day-1, respectively) or no additions for 3 weeks. Both drugs induced the HMG-CoA reductase activity in rat liver microsomes (isolated after 1, 2 and 3 weeks of treatment) to a similar extent. This indicates that the two drugs inhibited hepatic cholesterol synthesis to a comparable extent. During the whole treatment period no significant differences between control and drug-treated animals could be observed when the wet weight and protein content of the lenses were considered. However, a striking difference between the control group and pravastatin group (50 mg drug kg-1 diet) on the one hand and the simvastatin group (50 mg drug kg-1 diet) on the other was observed when the cholesterol content of the lenses were compared as a function of age. After 1 week of treatment all three groups showed the same increase in cholesterol content. Thereafter, the simvastatin group showed little additional increase, whereas the pravastatin group and the control group showed the same increase in cholesterol content (from 20 to 40 μg per lens). Even at a concentration of 100 mg kg-1 chow, pravastatin had no effect after 3 weeks, whereas at this concentration simvastatin already caused a reduction in lens cholesterol content after 7 days of treatment. Simvastatin in a concentration of 10 mg kg-1 chow reduced lens cholesterol by more than 2 5% after 3 weeks. So, we observed at least a ten-fold difference between both drugs in the ability to affect the cholesterol content of the lens in vivo. Furthermore, our observations indicate that in the avascular lens the accumulation of cholesterol with age is largely dependent on in situ de novo synthesis, and that under these in vivo conditions simvastatin, but not pravastatin, inhibits cholesterol synthesis in the lens. Chemicals/CAS: cholesterol, 57-88-5; pravastatin, 81131-74-0; simvastatin, 79902-63-9; Anticholesteremic Agents; Antilipemic Agents; Cholesterol, 57-88-5; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Lovastatin, 75330-75-5; Pravastatin, 81093-37-0; Simvastatin, 79902-63-9

Brown adipose tissue (BAT) combusts high amounts of fatty acids, thereby lowering plasma triglyceride levels and reducing obesity. However, the precise role of BAT in plasma cholesterol metabolism and atherosclerosis development remains unclear. Here we show that BAT activation by b3-adrenergic receptor stimulation protects from atherosclerosis in hyperlipidemic APOE3-Leiden.CETP mice, a well-established model for human-like lipoprotein metabolism that unlike hyperlipidemic Apoe-/-and Ldlr-/-mice expresses functional apoE and LDLR. BAT activation increases energy expenditure and decreases plasma triglyceride and cholesterol levels. Mechanistically, we demonstrate that BAT activation enhances the selective uptake of fatty acids from triglyceride-rich lipoproteins into BAT, subsequently accelerating the hepatic clearance of the cholesterol-enriched remnants. These effects depend on a functional hepatic apoE-LDLR clearance pathway as BAT activation in Apoe-/-and Ldlr-/-mice does not attenuate hypercholesterolaemia and atherosclerosis. We conclude that activation of BAT is a powerful therapeutic avenue to ameliorate hyperlipidaemia and protect from atherosclerosis. © 2015 Macmillan Publishers Limited.

An aberrant cholesterol metabolism in the brain may contribute to the pathogenesis of Alzheimer's disease (AD). The LDL receptor (LDLR) regulates plasma cholesterol levels and recently we and others obtained evidence that it is also involved in regulating brain cholesterol homeostasis. Moreover, we found that LDLR-deficient mice display impaired spatial memory. Because cholesterol, in part derived from cellular uptake via LDLR, is required for peripheral cell proliferation and growth, we examined the effect of absence of the LDLR on hippocampal proliferation and the density of synaptic connections. Mice deficient for the LDLR displayed a reduced number of proliferating (BrdU-labeled) cells in the hippocampus as compared to wild type control mice. In addition, the number of synaptophysin-immunoreactive presynaptic boutons in the hippocampal CA1 and the dentate gyrus (DG) areas, but not in cortical areas, was lower in the LDLR-knockout mice than in the control mice. In vitro experiments showed that LDLR activity is increased when cell growth is enhanced by the addition of N2 supplement. This further supports a role for the LDLR in the outgrowth of neurites. These findings support the notion that, similar to its role in the periphery, the LDLR is important for the cellular uptake of cholesterol in the brain and that disturbance of this process affects neuronal plasticity. © 2007 Elsevier Ireland Ltd and the Japan Neuroscience Society.

Benzene is an industrial chemical, component of automobile exhaust and cigarette smoke. After hepatic bioactivation benzene induces bone marrow, blood and hepatic toxicity. Using a toxicogenomics approach this study analysed the effects of benzene at three dose levels on gene expression in the liver after 28 daily doses. NMR based metabolomics was used to assess benzene exposure by identification of characteristic benzene metabolite profiles in urine. The 28-day oral exposure to 200 and 800 mg/kg/day but not 10 mg/kg/day benzene-induced hematotoxicity in male Fisher rats. Additionally these upper dose levels slightly reduced body weight and increased relative liver weights. Changes in hepatic gene expression were identified with oligonucleotide microarrays at all dose levels including the 10 mg/kg/day dose level where no toxicity was detected by other methods. The benzene-induced gene expression changes were related to pathways of biotransformation, glutathione synthesis, fatty acid and cholesterol metabolism and others. Some of the effects on gene expression observed here have previously been observed after induction of acute hepatic necrosis with bromobenzene and acetaminophen. In conclusion, changes in hepatic gene expression were found after treatment with benzene both at the toxic and non-toxic doses. The results from this study show that toxicogenomics identified hepatic effects of benzene exposure possibly related to toxicity. The findings aid to interpret the relevance of hepatic gene expression changes in response to exposure to xenobiotics. In addition, the results have the potential to inform on the mechanisms of response to benzene exposure. © 2005 Elsevier B.V. All rights reserved.

Rats were exposed to three levels of bromobenzene, sampled at 6, 24, and 48 h, and liver gene expression profiles were determined to identify dose and time-related changes. Expression of many genes changed transiently, and dependent on the dose. Few changes were identified after 6 h, but many genes were differentially expressed after 24 h, while after 48 h, only the high dose elicited large effects. Differentially expressed genes were involved in drug metabolism (upregulated GSTs, mEH, NQO1, Mrps, downregulated CYPs, sulfotransferases), oxidative stress (induced HO-1, peroxiredoxin, ferritin), GSH depletion (induced GCS-1, GSTA, GSTM) the acute phase response, and in processes like cholesterol, fatty acid and protein metabolism, and intracellular signaling. Trancriptional regulation via the electrophile and sterol response elements seemed to mediate part of the response to bromobenzene. Recovery of the liver was suggested in response to BB by the altered expression of genes involved in protein synthesis and cytoskeleton rearrangement. Furthermore, after 48 h, rats in the mid dose group showed no toxicity, and gene expression patterns resembled the normal situation. For certain genes (e.g., CYP4A, metallothioneins), intraday variation in expression levels was found, regardless of the treatment. Selected cDNA microarray measurements were confirmed using the specific and sensitive branched DNA signal amplification assay. © Society of Toxicology 2004; all rights reserved.

In previous work we have demonstrated suppression of cholesterol 7α-hydroxylase by bile acids at the level of mRNA and transcription, resulting in a similar decline in bile acid synthesis in cultured rat hepatocytes. In view of the substantial contribution of the 'alternative' or '27-hydroxylase' route to total bile acid synthesis, as demonstrated in cultured rat hepatocytes and in vivo in humans, we here evaluate the effects of various bile acids commonly found in bile of rats on the regulation of sterol 27-hydroxylase in cultured rat hepatocytes. Addition of taurocholic acid, the predominant bile acid in rat bile, to the culture medium of rat hepatocytes resulted in a 72% inhibition of sterol 27-hydroxylase activity. The effect was exerted at the level of sterol 27-hydroxylase mRNA, showing a time- and dose-dependent decline with a maximal suppression (-75%) at 50 μM taurocholic acid after 24 h of culture. The decline in mRNA followed first-order kinetics with an apparent half-life of 13 h. Under these conditions cholesterol 7α-hydroxylase mRNA (-91%) and bile acid synthesis (i.e. chenodeoxycholic and β-muricholic acid, -81%) were also maximally suppressed. In contrast, no change was found in the level of lithocholic acid 6β-hydroxylase mRNA. Assessment of the transcriptional activity of a number of genes involved in routing of cholesterol towards bile acids showed similar suppressive effects of taurocholate on expression of the sterol 27-hydroxylase and cholesterol 7α-hydroxylase genes (-43% and -42% respectively), whereas expression of the lithocholic 6β-hydroxylase gene was not affected. Taurocholic acid and unconjugated cholic acid were equally as effective in suppressing sterol 27-hydroxylase mRNA. The more hydrophobic bile acids, chenodeoxycholic acid and deoxycholic acid also produced a strong inhibition of 57% and 76% respectively whereas the hydrophilic β-muricholic acid was not active. We conclude that (1) a number of bile acids, at physiological concentrations, suppress sterol 27-hydroxylase by down-regulation of sterol 27-hydroxylase mRNA and transcriptional activity and (2) co-ordinated suppression of both sterol 27-hydroxylase and cholesterol 7α-hydroxylase results in inhibition of bile acid synthesis in cultured rat hepatocytes. Chemicals/CAS: chenodeoxycholic acid, 474-25-9; cholesterol 7alpha monooxygenase, 9037-53-0; cholic acid, 32500-01-9, 361-09-1, 81-25-4; deoxycholic acid, 83-44-3; lithocholic acid, 434-13-9; oxygenase, 9037-29-0, 9046-59-7; taurocholic acid, 145-42-6, 59005-70-8, 81-24-3; Adenosine Triphosphate, 56-65-5; Bile Acids and Salts; Cholesterol 7-alpha-Hydroxylase, EC 1.14.13.17; Cytochrome P-450 Enzyme System, 9035-51-2; cytochrome P-450C27/25, EC 1.14.-; Oxidoreductases, EC 1.; RNA, Messenger; Steroid Hydroxylases, EC 1.14.-; Taurocholic Acid, 81-24-3

OBJECTIVE - High-density lipoprotein (HDL) plays a key role in protection against development of atherosclerosis by reducing inflammation, protecting against LDL oxidation, and promoting reverse cholesterol transport from peripheral tissues to the liver for secretion into bile. Cholesterol 7α-hydroxylase (Cyp7a1) catalyzes the rate-limiting step in the intrahepatic conversion of cholesterol to bile acids that may have a role in HDL metabolism. We investigated the effect of Cyp7a1 deficiency on HDL metabolism in APOE*3-Leiden transgenic mice. METHODS AND RESULTS - Reduced bile acid biosynthesis in Cyp7a1-/-.APOE*3-Leiden mice versus APOE*3-Leiden mice did not affect total plasma cholesterol levels, but the distribution of cholesterol over various lipoproteins was different. Cholesterol was decreased in apoB-containing lipoproteins (ie, VLDL and IDL/LDL), whereas cholesterol was increased in HDL. The activity of PLTP and LCAT, which play a role in HDL catabolism, were not changed, and neither was HDL clearance. However, the hepatic cholesterol content was 2-fold increased, which was accompanied by a 2-fold elevated expression of hepatic ABCA1 and increased rate of cholesterol efflux from the liver to HDL. CONCLUSIONS - Strongly reduced bile acid synthesis in Cyp7a1-/-.APOE*3-Leiden mice leads to increased plasma HDL-cholesterol levels, as related to an increased hepatic expression of ABCA1. © 2006 American Heart Association, Inc. Chemicals / CAS: cholesterol 7alpha monooxygenase, 9037-53-0; phosphatidylcholine sterol acyltransferase, 9031-14-5; Apolipoprotein E3; ATP binding cassette transporter 1; ATP-Binding Cassette Transporters; Bile Acids and Salts; Cholesterol 7-alpha-Hydroxylase, EC 1.14.13.17; Cholesterol, HDL; Phosphatidylcholine-Sterol O-Acyltransferase, EC 2.3.1.43; phospholipid transfer protein, mouse; Phospholipid Transfer Proteins; RNA, Messenger

Background and aims Activation of brown adipose tissue (BAT) reduces both hyperlipidemia and atherosclerosis by increasing the uptake of triglyceride-derived fatty acids by BAT, accompanied by formation and clearance of lipoprotein remnants. We tested the hypothesis that the hepatic uptake of lipoprotein remnants generated by BAT activation would be accelerated by concomitant statin treatment, thereby further reducing hypercholesterolemia and atherosclerosis. Methods APOE*3-Leiden.CETP mice were fed a Western-type diet and treated without or with the selective β3-adrenergic receptor (AR) agonist CL316,243 that activates BAT, atorvastatin (statin) or both. Results β3-AR agonism increased energy expenditure as a result of an increased fat oxidation by activated BAT, which was not further enhanced by statin addition. Accordingly, statin treatment neither influenced the increased uptake of triglyceride-derived fatty acids from triglyceride-rich lipoprotein-like particles by BAT nor further lowered plasma triglyceride levels induced by β3-AR agonism. Statin treatment increased the hepatic uptake of the formed cholesterol-enriched remnants generated by β3-AR agonism. Consequently, statin treatment further lowered plasma cholesterol levels. Importantly, statin, in addition to β3-AR agonism, also further reduced the atherosclerotic lesion size as compared to β3-AR agonism alone, without altering lesion severity and composition. Conclusions Statin treatment accelerates the hepatic uptake of remnants generated by BAT activation, thereby increasing the lipid-lowering and anti-atherogenic effects of BAT activation in an additive fashion. We postulate that, in clinical practice, combining statin treatment with BAT activation is a promising new avenue to combat hyperlipidemia and cardiovascular disease.

Background: The prevalence of dyslipidemia and obesity resulting from excess energy intake and physical inactivity is increasing. The liver plays a pivotal role in systemic lipid homeostasis. Effective, natural dietary interventions that lower plasma lipids and promote liver health are needed. Objective: Our goal was to determine the effect of dietary sphingolipids on plasma lipids and liver steatosis. Design: APOE*3Leiden mice were fed a Western-type diet supplemented with different sphingolipids. Body cholesterol and triacylglycerol metabolism as well as hepatic lipid concentrations and lipid-related gene expression were determined. Results: Dietary sphingolipids dose-dependently lowered both plasma cholesterol and triacylglycerol in APOE*3Leiden mice; 1% phytosphingosine (PS) reduced plasma cholesterol and triacylglycerol by 57% and 58%, respectively. PS decreased the absorption of dietary cholesterol and free fatty acids by 50% and 40%, respectively, whereas intestinal triacylglycerol lipolysis was not affected. PS increased hepatic VLDL-triacylglycerol production by 20%, whereas plasma lipolysis was not affected. PS increased the hepatic uptake of VLDL remnants by 60%. Hepatic messenger RNA concentrations indicated enhanced hepatic lipid synthesis and VLDL and LDL uptake. The net result of these changes was a strong decrease in plasma cholesterol and triacylglycerol. The livers of 1% PS-fed mice were less pale, 22% lighter, and contained 61% less cholesteryl ester and 56% less triacylglycerol than livers of control mice. Furthermore, markers of liver inflammation (serum amyloid A) and liver damage (alanine aminotransferase) decreased by 74% and 79%, respectively, in PS-fed mice. Conclusion: Sphingolipids lower plasma cholesterol and triacylglycerol and protect the liver from fat- and cholesterol-induced steatosis. © 2006 American Society for Nutrition.Chemicals / CAS: alanine aminotransferase, 9000-86-6, 9014-30-6; amyloid, 11061-24-8; cholesterol, 57-88-5; phytosphingosine, 13552-11-9, 554-62-1; RNA, 63231-63-0; apolipoprotein E3 (Leidein); Apolipoprotein E3; Apolipoproteins E; Cholesterol, 57-88-5; Cholesterol, Dietary; Fatty Acids, Nonesterified; Lipoproteins, VLDL; RNA, 63231-63-0; Sphingolipids; Triglycerides

The present study describes the effects of atorvastatin on whole body synthesis of nitric oxide (NO), prostacyclin (PGI2), and thromboxane A2 (TxA2), on oxidative stress and nitrite/nitrate-related renal carbonic anhydrase (CA) activity in patients with type 2 diabetes mellitus (T2DM). A double-blind, randomized, placebo-controlled parallel-group trial (the DALI study group) on 217 patients with T2DM and dyslipidemia was performed. Urinary samples were collected before and after administration of a standard dose (10 mg/d, n = 73), a maximal dose atorvastatin (80 mg/d, n = 72) or placebo (n = 72) for 30 weeks. Urinary nitrite and nitrate were measured to assess whole body NO synthesis. The urinary molar ratio of nitrate to nitrite (UNOxR) served as a measure of renal CA activity. Free radical- and cyclooxygenase (COX)-catalyzed lipid peroxidation was estimated by measuring urinary 8-iso-prostaglandin F2α (8-iso-PGF2α). In subgroups, systemic PGI2 and TxA2 synthesis was assessed by measuring their major urinary metabolites 2,3-dinor-6-keto-prostaglandin F1α and 2,3-dinor-thromboxane B2, respectively. All biochemical parameters were measured by GC-MS and GC-MS/MS methods. T2DM patients had elevated levels of nitrate, nitrite, UNOxR, and 8-iso-PGF2α compared to healthy non-diabetic and normolipidemic subjects. Thirty-week treatment with atorvastatin (10 or 80 mg/d) did not significantly alter NO, PGI2, TxA2 and 8-iso-PGF2α synthesis and did not improve the renal reabsorption of nitrite which is considered an important reservoir of NO. Our study suggests that atorvastatin (10 or 80 mg/d) does not provide cardiovascular benefit beyond its cholesterol lowering effect in patients with T2DM. © 2015 Elsevier Ltd. All rights reserved.

In this study, we applied the multivariate statistical tool Partial Least Squares (PLS) to analyze the relative importance of 83 plasma proteins in relation to coronary heart disease (CHD) mortality and the intermediate end points body mass index, HDL-cholesterol and total cholesterol. From a Dutch monitoring project for cardiovascular disease risk factors, men who died of CHD between initial participation (1987-1991) and end of follow-up (January 1, 2000) (N = 44) and matched controls (N = 44) were selected. Baseline plasma concentrations of proteins were measured by a multiplex immunoassay. With the use of PLS, we identified 15 proteins with prognostic value for CHD mortality and sets of proteins associated with the intermediate end points. Subsequently, sets of proteins and intermediate end points were analyzed together by Principal Components Analysis, indicating that proteins involved in inflammation explained most of the variance, followed by proteins involved in metabolism and proteins associated with total-C. This study is one of the first in which the association of a large number of plasma proteins with CHD mortality and intermediate end points is investigated by applying multivariate statistics, providing insight in the relationships among proteins, intermediate end points and CHD mortality, and a set of proteins with prognostic value. © 2009 American Chemical Society.

Objective-Cholesterol 7α-hydroxylase (cyp7a1) catalyzes the rate-limiting step in conversion of cholesterol to bile acids. To study the relationship between bile acid biosynthesis and triglyceride metabolism, we cross-bred mice lacking cyp7a1 on a hyperlipidemic APOE*3-Leiden background. Methods and Results-Female mice received a chow or lipogenic diet. On both diets, fecal bile acid excretion was 70% decreased concomitantly with a 2-fold increased neutral sterol output. The differences in bile acid biosynthesis did not change plasma cholesterol levels. However, plasma triglyceride levels decreased by 41% and 38% in the cyp7a1-/- APOE*3-Leiden mice as compared with APOE*3-Leiden mice on chow and lipogenic diet, respectively. Mechanistic studies showed that very-low-density lipoprotein (VLDL)-apolipoprotein B and VLDL-triglyceride production rates were reduced in cyp7a1-/-.APOE*3-Leiden mice as compared with APOE*3-Leiden mice (-34% and -35%, respectively). Cyp7a1 deficiency also increased the hepatic cholesteryl ester and triglyceride content (2.8-fold and 2.5-fold, respectively). In addition, hepatic anti-oxidative vitamin content, which can influence VLDL-production, was lower. Hepatic mRNA analysis showed decreased expression of genes involved in lipogenesis including srebf1. Conclusions-Cyp7a1 deficiency in APOE*3-Leiden mice decreases the VLDL particle production rate, as a consequence of a strongly reduced bile acid biosynthesis, leading to a decrease in plasma triglycerides. These data underscore the close relationship between bile acid biosynthesis and triglyceride levels. Chemicals / CAS: cholesterol 7alpha monooxygenase, 9037-53-0; cholesterol, 57-88-5; acyltransferase, 9012-30-0, 9054-54-0; alpha tocopherol, 1406-18-4, 1406-70-8, 52225-20-4, 58-95-7, 59-02-9; diacylglycerol acyltransferase, 9029-98-5; retinol, 68-26-8, 82445-97-4; Acyltransferases, EC 2.3.-; apolipoprotein E3 (Leidein); Apolipoprotein E3; Apolipoproteins B; Apolipoproteins E; Bile Acids and Salts; Cholesterol 7-alpha-Hydroxylase, EC 1.14.13.17; Cholesterol Esters; Dgat1 protein, mouse, EC 2.3.1.20; Diacylglycerol O-Acyltransferase, EC 2.3.1.20; Ketone Bodies; Lipoproteins, VLDL; RNA, Messenger; Sterols; Triglycerides; Vitamin A, 11103-57-4; Vitamin E, 1406-18-4