Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Premature atherosclerosis and cardiac complications have been reported among the systemic manifestations of cerebrotendinous xanthomatosis (CTX), a rare bile acid disorder with predominantly neurological features. In some cases, myocardial infarction has been the cause of sudden death. We examined nine CTX patients to determine whether they also had clinical or subclinical signs of cardiovascular disorders. In four of them, transthoracic echocardiography showed thickening of the interatrial septum compatible with lipomatous hypertrophy. The unexpected association of the two abnormalities is unlikely to be coincidental and suggests that careful cardiac examination should be considered, even in the absence of clinical manifestations.
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PMID:Cerebrotendinous xanthomatosis: evidence of lipomatous hypertrophy of the atrial septum. 980 40

The effects of combination therapy with chenodeoxycholic acid (CDCA) and simvastatin on serum cholestanol, low-density lipoprotein (LDL) cholesterol, and lathosterol levels were investigated in seven adult patients with cerebrotendinous xanthomatosis (CTX) who were on long-term treatment with CDCA. The patients were treated with a combination of CDCA 750 mg daily and an increasing dose of simvastatin from 10 mg to 40 mg daily for a period of 6 months. We found a significant effect of this combination therapy compared with CDCA alone in terms of decreasing the serum cholestanol and LDL cholesterol levels, particularly with a daily dose of 40 mg simvastatin. The mean cholestanol level decreased from 9.27 micromol/L (baseline) to 6.69 micromol/L (40 mg simvastatin), while the mean LDL cholesterol level decreased from 5.08 mmol/L (baseline) to 3.04 mmol/L (40 mg simvastatin). No side effects were reported, and there were no effects on the clinical condition, cerebral magnetic resonance imaging (MRI), visual evoked potentials, and electroencephalographic features. We conclude that a combination of 750 mg CDCA and 40 mg simvastatin daily is effective to further reduce serum cholestanol, LDL cholesterol, and lathosterol in adult CTX patients treated with long-term CDCA. Whether this combination treatment will be effective for the long-term prevention of neurological deterioration and atherosclerosis remains to be established.
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PMID:Effect of simvastatin in addition to chenodeoxycholic acid in patients with cerebrotendinous xanthomatosis. 1002 88

27-Hydroxycholesterol (27OH) is the major oxysterol in human atherosclerotic lesions, followed by 7-ketocholesterol (7K). Whereas 7K probably originates nonenzymically, 27OH arises by the action of sterol 27-hydroxylase, a cytochrome P450 enzyme expressed at particularly high levels in the macrophage and proposed to represent an important pathway by which macrophages eliminate excess cholesterol. We hypothesized and here show that 27-hydroxylated 7-ketocholesterol (270H-7K) is present in human lesions, probably generated by the action of sterol 27-hydroxylase on 7K. Moreover, [(3)H]27OH-7K was produced by human monocyte-derived macrophages (HMDMs) supplied with [(3)H]7K but not in HMDMs from a patient with cerebrotendinous xanthomatosis (CTX) shown to have a splice-junction mutation of sterol 27-hydroxylase. Whereas [(3)H]27OH-7K was predominantly secreted into the medium, [(3)H]-27OH formed from [(3)H]-cholesterol was mostly cell-associated. The majority of supplied [(3)H]7K was metabolized beyond 27OH-7K to aqueous-soluble products (apparently bile acids derived from the sterol 27-hydroxylase pathway). Metabolism to aqueous-soluble products was ablated by a sterol 27-hydroxylase inhibitor and absent in CTX cells. Sterol 27-hydroxylase therefore appears to represent an important pathway by which macrophages eliminate not only cholesterol but also oxysterols such as 7K. The fact that 7K (and cholesterol) still accumulates in lesions and foam cells indicates that this pathway may be perturbed in atherosclerosis and affords a new opportunity for the development of therapeutic strategies to regress atherosclerotic lesions.
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PMID:Sterol 27-hydroxylase acts on 7-ketocholesterol in human atherosclerotic lesions and macrophages in culture. 1086 58

Statins decrease the hepatic biosynthesis of cholesterol, and reduce the incidence of myocardial infarction in women who have already experienced a myocardial infarction. Statins also reduce the risk of atherosclerosis in diabetic patients, but it is unknown whether they influence the glucose tolerance. It has further been suggested that they may influence bone metabolism. Vitamin C is an antioxidant and it decreases serum cholesterol moderately. Antioxidants may also have other metabolic effects, but these are insufficiently studied. The aim of the present study was to investigate the metabolic effects of the cholesterol-lowering agent fluvastatin and the antioxidant vitamin C. Sixty-eight elderly, postmenopausal women with osteoporosis and mild hypercholesterolemia were randomly assigned to 12 weeks open treatment with either fluvastatin (40 mg daily) + 500 mg vitamin C (n = 45) or vitamin C only (n = 23). We measured biochemical markers of bone formation (serum osteocalcin and total alkaline phosphatase) and bone resorption (serum and urinary CTX), parameters related to diabetes and serum lipids and lipoproteins. Fluvastatin in combination with vitamin C had no effect on bone formation markers. We found a weak decrease in parameters of bone resorption, which was significant from baseline, but not different between the two groups. There were no significant effects on any of the other markers of either fluvastatin or vitamin C. The lipid-lowering effect of fluvastatin was confirmed with a decrease of 20% and 30% in serum total cholesterol and LDL-cholesterol, respectively. We conclude that fluvastatin given in clinically relevant doses has no influence on parameters of bone remodeling. Other statins remain to be investigated.
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PMID:The effect of fluvastatin on parameters of bone remodeling. 1144 86

Among the models of dyslipidemia and atherosclerosis, a number of wild-type, naturally defective, and genetically modified animals (rabbits, mice, pigeons, dogs, pigs, and monkeys) have been characterized. In particular, their similarities to and differences from humans in respect to relevant biochemical, physiologic, and pathologic conditions have been evaluated. Features of atherosclerotic lesions and their specific relationship to plasma lipoprotein particles have been critically reviewed and summarized. All animal models studied have limitations: the most significant advantages and disadvantages of using a specific animal species are outlined here. New insights in lipid metabolism and genetic background with regard to variations in pathogenesis of dyslipidemia-associated atherogenesis have also been reviewed. Evidence suggests that among wild-type species, strains of White Carneau pigeons and Watanabe Heritable Hyperlipidemic and St. Thomas's Hospital rabbits are preferable to the cholesterol-fed wild-type animal species in dyslipidemia and atherosclerosis research. Evidence for the usefulness of both wild-type and transgenic animals in studying the involvement of inflammatory pathways and Chlamydia pneumoniae infection in pathogenesis of atherosclerosis has also been summarized. Transgenic mice and rabbits are excellent tools for studying specific gene-related disorders. However, despite these significant achievements in animal experimentation, there are no suitable animal models for several rare types of fatal dyslipidemia-associated disorders such as phytosterolemia and cerebrotendinous xanthomatosis. An excellent model of diabetic atherosclerosis is unavailable. The question of reversibility of atherosclerosis still remains unanswered. Further work is needed to overcome these deficiencies.
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PMID:Advances in experimental dyslipidemia and atherosclerosis. 1155 65

Increased levels of plasma sterols other than cholesterol can serve as markers for abnormalities in lipid metabolism associated with clinical disease. Premature atherosclerosis and xanthomatosis occur in two rare lipid storage diseases, Cerebrotendinous xanthomatosis (CTX) and sitosterolemia. In CTX, cholestanol is present in all tissues. In sitosterolemia, dietary campesterol and sitosterol accumulate in plasma and red blood cells. Plasma accumulation of oxo-sterols is associated with inhibition of bile acid synthesis and other abnormalities in plasma lipid metabolism. Inhibition of cholesterol biosynthesis is associated with plasma appearance of precursor sterols. The increases in non-cholesterol sterols, while highly significant, represent only minor changes in plasma sterols, which require capillary gas-liquid chromatography and MS for effective detection, identification and quantification.
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PMID:Plasma non-cholesterol sterols. 1176 75

The CYP27 gene is expressed in arterial endothelium, macrophages, and other tissues. The gene product generates sterol intermediates that function as ligands for nuclear receptors prior to their transport to the liver for metabolism, mostly to bile acids. Most attention has been given to 27-hydroxycholesterol as a ligand for LXR activated receptors and to chenodeoxycholic acid as a ligand for farnesoid X activated receptors (FXRs). Expression of the pathway in macrophages is essential for normal reverse cholesterol transport. Thus, ABC transporter activity is upregulated, which enhances cholesterol efflux. Absence of these mechanisms probably accounts for the accelerated atherosclerosis that occurs in cerebrotendinous xanthomatosis. Accumulation of 27-hydroxycholesterol in human atheroma is puzzling and may reflect low levels of oxysterol 7alpha-hydroxylase activity in human macrophages. The same enzyme determines the proportion of mono-, di-, and tri-hydroxy bile acids synthesized in the liver. Oxysterol 7alpha-hydroxylase deficiency is a molecular basis for cholestatic liver disease. Chenodeoxycholic acid, the major normal end product, downregulates expression of cholesterol 7alpha-hydroxylase via the FXR/short heterodimer protein nuclear receptor and thus limits total bile acid production. The challenge is to quantify in a physiologic setting the magnitude of the pathway in different tissues and to further evaluate the biologic roles of all the intermediates that may function as ligands for orphan nuclear receptors or via other regulatory mechanisms.
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PMID:25R,26-Hydroxycholesterol revisited: synthesis, metabolism, and biologic roles. 1197 35

Follow-up investigations were undertaken on a previously reported patient who had severe familial giant cell hepatitis in infancy associated with substantially increased urinary excretion of bile alcohol glucuronides. By the age of 11 years, he had developed a profile of cholanoids in plasma and urine that closely resembled the pattern seen in cerebrotendinous xanthomatosis (CTX). Sequencing of the sterol 27-hydroxylase gene (CYP27A) showed that he was homozygous for a deletion (525/526delG) that causes a frameshift and a premature stop codon. This genotype has previously been described in an adult female with classical symptoms of CTX (tendon xanthomata, cataracts and deteriorating cognitive function). A review of past medical histories of a group of patients with CTX revealed that prolonged neonatal cholestatic jaundice was common. The family histories also revealed fetal and neonatal deaths among siblings of patients with CTX. We conclude that defective activity of cholesterol 27-hydroxylase can lead to neonatal cholestatic jaundice ('hepatitis of infancy'), which may be self-limiting. After a latent period, however, progressive accumulation of cholesterol and cholestanol can lead to the xanthomata, neurodegeneration, cataracts and atherosclerosis that are typical of CTX.
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PMID:Mutations in the sterol 27-hydroxylase gene (CYP27A) cause hepatitis of infancy as well as cerebrotendinous xanthomatosis. 1255 43

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive lipid-storage disorder characterised by xanthomas, neurological dysfunctions and premature atherosclerosis. A case of a well differentiated adenocarcinoma of the gallbladder occurring in a 57-year-old Japanese man with CTX, confirmed clinically, biochemically and at autopsy is reported together with analyses of the sterol 27-hydroxylase (CYP27) and p53 genes. A missense mutation of the p53 (G for C) was detected in the gallbladder adenocarcinoma. Direct sequence analysis also showed a silent mutational substitution of unknown significance, C for A, in CYP27 at codon 89. In the past, CTX patients have only demonstrated this infrequently, indicating no direct relationship between CYP27 dysfunction and tumour development. Thus, the present case of gallbladder cancer appears to be a chance occurrence.
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PMID:An autopsy case of gallbladder cancer developing in a Japanese man with cerebrotendinous xanthomatosis: genetic analysis of the sterol 27-hydroxylase and p53 genes. 1274 62

The mitochondrial sterol 27-hydroxylase (CYP27A1) is required for degradation of the C27-sterol side chain in bile acid biosynthesis. CYP27A1 seems, however, to have roles beyond this, as illustrated by patients with a deficient sterol 27-hydroxylase due to mutations of the CYP27A1 gene [cerebrotendinous xanthomatosis (CTX)]. These subjects have symptoms ranging from accumulation of bile alcohols and cholestanol to accelerated atherosclerosis and progressive neurologic impairment. The present work describes a detailed investigation on the substrate specificity of recombinant human CYP27A1. In accordance with some previous work with rat liver mitochondria, the activity in general increased with the polarity of the substrate. An obvious example was the finding that cholesterol was 27-hydroxylated more efficiently than cholesterol oleate but less efficiently than cholesterol sulfate. The oxysterols 24S-hydroxycholesterol and 25-hydroxycholesterol were 27-hydroxylated less efficiently than cholesterol, possibly due to steric hindrance. Surprisingly, sterols with a 3-oxo-Delta4 structure were found to be hydroxylated at a much higher rate than the corresponding sterols with a 3beta-hydroxy-Delta5 structure. The rates of hydroxylation of the sterols were: 7alpha-hydroxy-4-cholesten-3-one>4-cholesten-3-one>7alpha-hydroxycholesterol>24-hydroxy-4-cholesten-3-one> cholesterol>25-hydroxy-4-cholesten-3-one>24-hydroxycholesterol>or=25-hydroxycholesterol. The possibility is discussed that the findings may have implications for oxysterol-mediated regulation of gene expression. The very high activity of CYP27A1 towards the cholestanol precursor 4-cholesten-3-one may be of importance in connection with the accumulation of cholestanol in patients with CTX.
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PMID:On the substrate specificity of human CYP27A1: implications for bile acid and cholestanol formation. 1277 73


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