| 1. |
- Abdel-Khalik, Jonas, et al.
(author)
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Bile acid biosynthesis in Smith-Lemli-Opitz syndrome bypassing cholesterol: Potential importance of pathway intermediates.
- 2021
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In: The Journal of steroid biochemistry and molecular biology. - : Elsevier BV. - 1879-1220 .- 0960-0760. ; 206
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Journal article (peer-reviewed)abstract
- Bile acids are the end products of cholesterol metabolism secreted into bile. They are essential for the absorption of lipids and lipid soluble compounds from the intestine. Here we have identified a series of unusual Δ5-unsaturated bile acids in plasma and urine of patients with Smith-Lemli-Opitz syndrome (SLOS), a defect in cholesterol biosynthesis resulting in elevated levels of 7-dehydrocholesterol (7-DHC), an immediate precursor of cholesterol. Using liquid chromatography - mass spectrometry (LC-MS) we have uncovered a pathway of bile acid biosynthesis in SLOS avoiding cholesterol starting with 7-DHC and proceeding through 7-oxo and 7β-hydroxy intermediates. This pathway also occurs to a minor extent in healthy humans, but elevated levels of pathway intermediates could be responsible for some of the features SLOS. The pathway is also active in SLOS affected pregnancies as revealed by analysis of amniotic fluid. Importantly, intermediates in the pathway, 25-hydroxy-7-oxocholesterol, (25R)26-hydroxy-7-oxocholesterol, 3β-hydroxy-7-oxocholest-5-en-(25R)26-oic acid and the analogous 7β-hydroxysterols are modulators of the activity of Smoothened (Smo), an oncoprotein that mediates Hedgehog (Hh) signalling across membranes during embryogenesis and in the regeneration of postembryonic tissue. Computational docking of the 7-oxo and 7β-hydroxy compounds to the extracellular cysteine rich domain of Smo reveals that they bind in the same groove as both 20S-hydroxycholesterol and cholesterol, known activators of the Hh pathway.
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| 2. |
- Besga, A., et al.
(author)
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Differences in brain cholesterol metabolism and insulin in two subgroups of patients with different CSF biomarkers but similar white matter lesions suggest different pathogenic mechanisms
- 2012
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In: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 510:2, s. 121-126
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Journal article (peer-reviewed)abstract
- Investigate possible associations of white matter hyperintensities (WMHs) with the metabolism of cholesterol and insulin in two subgroups of patients with memory complaints and different CSF A beta 42 and CSF tau levels. 59 patients from the memory clinic at Karolinska Hospital were included. Degree of WMHs was rated using the ARWMC scale and the following biomarkers were measured in CSF and plasma: insulin, cholesterol, lanosterol, lathosterol, and oxidized cholesterol metabolites. The WMHs in CSF control-like group correlated with increased brain cholesterol synthesis and reduced efflux of oxysterols and insulin in CSF. In the CSF AD-like group, the WMHs correlated with increased peripheral cholesterol metabolism. Despite having similar appearance on FLAIR images, the pathogenic mechanisms of WMHS are likely to be different in the two groups investigated.
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| 3. |
- Bodin, Karl, et al.
(author)
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Metabolism of 4 beta -hydroxycholesterol in humans
- 2002
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 277:35, s. 31534-31540
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Journal article (peer-reviewed)abstract
- One of the major oxysterols in the human circulation is 4 beta-hydroxycholesterol formed from cholesterol by the drug-metabolizing enzyme cytochrome P450 3A4. Deuterium-labeled 4 beta-hydroxycholesterol was injected into two healthy volunteers, and the apparent half-life was found to be 64 and 60 h, respectively. We have determined earlier the half-lives for 7 alpha-, 27-, and 24-hydroxycholesterol to be approximately 0.5, 0.75, and 14 h, respectively. Patients treated with certain antiepileptic drugs have up to 20-fold increased plasma concentrations of 4 beta-hydroxycholesterol. The apparent half-life of deuterium-labeled 4 beta-hydroxycholesterol in such a patient was found to be 52 h, suggesting that the high plasma concentration was because of increased synthesis rather than impaired clearance. 4 beta-Hydroxycholesterol was converted into acidic products at a much slower rate than 7 alpha-hydroxycholesterol in primary human hepatocytes, and 4 beta-hydroxycholesterol was 7 alpha-hydroxylated at a slower rate than cholesterol by recombinant human CYP7A1. CYP7B1 and CYP39A1 had no activity toward 4 beta-hydroxycholesterol. These results suggest that the high plasma concentration of 4 beta-hydroxycholesterol is because of its exceptionally slow elimination, probably in part because of the low rate of 7 alpha-hydroxylation of the steroid. The findings are discussed in relation to a potential role of 4 beta-hydroxycholesterol as a ligand for the nuclear receptor LXR.
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| 4. |
- Bountouvi, Evangelia, et al.
(author)
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Longitudinal Data in Patients with Niemann-Pick Type C Disease Under Combined High Intrathecal and Low Intravenous Dose of 2-hydroxylpropyl-β-cyclodextrin.
- 2021
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In: Innovations in clinical neuroscience. - 2158-8333. ; 18:1-3, s. 11-16
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Journal article (peer-reviewed)abstract
- Niemann-Pick Type C disease (NPC) is a rare, incurable, autosomal-recessive, lysosomal storage disorder with protean and progressive neurovisceral manifestations characterized by accumulation of intracellular unesterified cholesterol. The investigational use of 2-hydroxypropyl-beta-cyclodextrin (HP-β-CD) in the treatment of NPC has shown promising results in improving life expectancy and reducing neurological damage in this patient population. This case report describes two children with the neurological form of NPC: a 5-year-old male patient in advanced stage of the disease and an 11-year-old female patient in moderately advanced stage. Despite treatment with the enzyme inhibitor, miglustat, both patients continued to exhibit severe neurodegeneration. High intrathecal (900mg) and low intravenous (350-500mg/kg) doses of HP-β-CD (Trappsol®Cyclo™) were administrated twice monthly to the patients in addition to miglustat therapy. The patients were monitored clinically as well as by imaging, laboratory, and biomarker (e.g., total tau protein [T-tau]; phosphorylated tau [P-tau]; neurofilament light [NFL], oxysterols) studies over a period of 16 to 22 months. The combination therapy of miglustat and HP-β-CD resulted in disease stabilization in both patients. The combination therapy demonstrated a good safety profile, and no adverse effects on hearing were observed. Additionally, CSF biomarkers appeared useful in monitoring neuronal damage. Large, randomized studies are needed to confirm these findings.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Heverin, Maura, et al.
(author)
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On the regulatory importance of 27-hydroxycholesterol in mouse liver
- 2017
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In: Journal of Steroid Biochemistry and Molecular Biology. - : Elsevier. - 0960-0760 .- 1879-1220. ; 169, s. 10-21
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Research review (peer-reviewed)abstract
- 27-Hydroxycholesterol (27OH) is a strong suppressor of cholesterol synthesis and a weak activator of LXR in vitro. The regulatory importance of 27OH in vivo is controversial. Here we utilized male mice with increased levels of 27OH either due to increased production (CYP27A1 transgenic mice) or reduced metabolism (Cyp7b1-/- mice). We also used mice lacking 27OH due to a knockout of Cyp27a1. The latter mice were treated with cholic acid to compensate for reduced bile acid synthesis. The effects of the different levels of 27OH on Srebp- and other LXR-regulated genes in the liver were investigated. In the liver of CYP27tg mice we found a modest increase of the mRNA levels corresponding to the LXR target genes Cyp7b1 and Abca1. A number of other LXR-regulated genes were not affected. The effect on Abca1 mRNA was not seen in the liver of Cyp7b1-/- mice. There were little or no effects on cholesterol synthesis. In the liver of the Cyp27-/- mice treated with 0.025% cholic acid there was no significant effect of the knockout on the LXR target genes. In a previous work triple-knockout mice deficient in the biosynthesis of 24S-hydroxycholesterol, 25-hydroxycholesterol and 27OH were shown to have impaired response to dietary cholesterol, suggesting side-chain oxidized oxysterols to be mediators in cholesterol-induced effects on LXR target genes at a transcriptional level (Chen W. et al., Cell Metab. 5 (2007) 73-79). The hydroxylated oxysterol responsible for the effect was not defined. We show here that treatment of wildtype mice with dietary cholesterol under the same conditions as in the above study induced the LXR target genes Lpl, Abcg8 and Srebp1c in wild type mice but failed to activate the same genes in mice lacking 27-hydroxycholesterol due to a knockout of Cyp27. We failed to demonstrate the above effects at the protein level (Abcg8) or at the activity level (Lpl). The results suggest that 27OH is not an important regulator of Srebp- or LXR regulated genes under basal conditions in mouse liver. On the other hand 27OH appears to mediate cholesterol-induced effects on some LXR target genes at a transcriptional level under some in vivo conditions.
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| 9. |
- Keller, Lina, et al.
(author)
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A Functional Polymorphism In The Hmgcr Promoter Affects Transcriptional Activity But Not The Risk For Alzheimer Disease In Swedish Populations
- 2010
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In: Brain Research. - Amsterdam : Elsevier. - 0006-8993 .- 1872-6240. ; 1344, s. 185-91
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Journal article (peer-reviewed)abstract
- Variations in genes associated with cholesterol homeostasis have been reported to modify the risk of developing Alzheimer disease (AD). To date there have been few investigations into variations in genes directly involved in cholesterol biosynthesis and AD. We investigated the influence of the -911C>A polymorphism (rs3761740) in the hydroxy-methyl-glutaryl CoA reductase (HMGCR) gene promoter on basal and regulated transcription, plasma cholesterol levels and the association with AD. Under in vitro conditions the A allele was found to be significantly more responsive to SREBP-2 mediated regulation than the C allele. In an age and sex matched case-control study, the genotype distribution and allele frequency of this polymorphism were not associated with AD (OR=1.03; 95% CI=0.72-1.48). However, we did find evidence supporting an interaction between the HMGCR A allele, the APOE E4 allele and an altered risk of AD (OR=2.41; 95% CI=0.93-6.22).
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| 10. |
- Kober, Alexandra Carmen, et al.
(author)
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Implications of cerebrovascular ATP-binding cassette transporter G1 (ABCG1) and apolipoprotein M in cholesterol transport at the blood-brain barrier
- 2017
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In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier BV. - 1388-1981. ; 1862:6, s. 573-588
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Journal article (peer-reviewed)abstract
- Impaired cholesterol/lipoprotein metabolism is linked to neurodegenerative diseases such as Alzheimer's disease (AD). Cerebral cholesterol homeostasis is maintained by the highly efficient blood-brain barrier (BBB) and flux of the oxysterols 24(S)-hydroxycholesterol and 27-hydroxycholesterol, potent liver-X-receptor (LXR) activators. HDL and their apolipoproteins are crucial for cerebral lipid transfer, and loss of ATP binding cassette transporters (ABC)G1 and G4 results in toxic accumulation of oxysterols in the brain. The HDL-associated apolipoprotein (apo)M is positively correlated with pre-β HDL formation in plasma; its presence and function in the brain was thus far unknown. Using an in vitro model of the BBB, we examined expression, regulation, and functions of ABCG1, ABCG4, and apoM in primary porcine brain capillary endothelial cells (pBCEC). RT Q-PCR analyses and immunoblotting revealed that in addition to ABCA1 and scavenger receptor, class B, type I (SR-BI), pBCEC express high levels of ABCG1, which was up-regulated by LXR activation. Immunofluorescent staining, site-specific biotinylation and immunoprecipitation revealed that ABCG1 is localized both to early and late endosomes and on apical and basolateral plasma membranes. Using siRNA interference to silence ABCG1 (by 50%) reduced HDL-mediated [3H]-cholesterol efflux (by 50%) but did not reduce [3H]-24(S)-hydroxycholesterol efflux. In addition to apoA-I, pBCEC express and secrete apoM mainly to the basolateral (brain) compartment. HDL enhanced expression and secretion of apoM by pBCEC, apoM-enriched HDL promoted cellular cholesterol efflux more efficiently than apoM-free HDL, while apoM-silencing diminished cellular cholesterol release. We suggest that ABCG1 and apoM are centrally involved in regulation of cholesterol metabolism/turnover at the BBB.
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| 11. |
- Latorre-Leal, María, et al.
(author)
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CYP46A1-mediated cholesterol turnover induces sex-specific changes in cognition and counteracts memory loss in ovariectomized mice
- 2024
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In: Science advances. - 2375-2548. ; 10:4
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Journal article (peer-reviewed)abstract
- The brain-specific enzyme CYP46A1 controls cholesterol turnover by converting cholesterol into 24S-hydroxycholesterol (24OH). Dysregulation of brain cholesterol turnover and reduced CYP46A1 levels are observed in Alzheimer's disease (AD). In this study, we report that CYP46A1 overexpression in aged female mice leads to enhanced estrogen signaling in the hippocampus and improved cognitive functions. In contrast, age-matched CYP46A1 overexpressing males show anxiety-like behavior, worsened memory, and elevated levels of 5α-dihydrotestosterone in the hippocampus. We report that, in neurons, 24OH contributes to these divergent effects by activating sex hormone signaling, including estrogen receptors. CYP46A1 overexpression in female mice protects from memory impairments induced by ovariectomy while having no effects in gonadectomized males. Last, we measured cerebrospinal fluid levels of 24OH in a clinical cohort of patients with AD and found that 24OH negatively correlates with neurodegeneration markers only in women. We suggest that CYP46A1 activation is a valuable pharmacological target for enhancing estrogen signaling in women at risk of developing neurodegenerative diseases.
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| 12. |
- Lundström, Nils-Rune, et al.
(author)
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Svårt hjärtsjuka barn från Balkan opererades i Sverige : Redogörelse för 41 barn som behandlats via lyckad hjälpinsats
- 2006
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In: Läkartidningen. - 0023-7205 .- 1652-7518. ; 103:50-52, s. 4038-4041
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Journal article (peer-reviewed)abstract
- The Swedish Medical Program is a co-operation between Linköping University Hospital and the International Organisation for Migration (IOM) for medical support to Bosnia and Hercegovina and to Kosovo. Within this program 41 infants and children from Bosnia-Hercegovina and Kosovo with severe heart disease were transferred to Sweden during the period 1995 - 2003 for treatment, with good results. The program enabled pediatric cardiologists and surgeons from these countries to visit Sweden for shorter training periods and Swedish doctors to supervise local clinicians in these countries. With support from an Austrian team a limited number of children with heart malformations have been treated locally since 2002. It is the intention of the Swedish program to further support the establishment of pediatric heart surgery in Sarajevo.
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| 13. |
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| 14. |
- Norlin, Maria, et al.
(author)
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On the substrate specificity of human CYP27A1: implications for bile acid and cholestanol formation
- 2003
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In: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 44:8, s. 1515-1522
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Journal article (peer-reviewed)abstract
- 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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| 15. |
- Norlin, Maria, et al.
(author)
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Oxysterol 7 alpha-hydroxylase activity by cholesterol 7 alpha-hydroxylase (CYP7A)
- 2000
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 275:44, s. 34046-34053
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Journal article (peer-reviewed)abstract
- A 7 alpha-hydroxylation is necessary for conversion of both cholesterol and 27-hydroxycholesterol into bile acids. According to current theories, cholesterol 7 alpha-hydroxylase (CYP7A) is responsible for the former and oxysterol 7 alpha-hydroxylase (CYP7B) for the latter reaction. CYP7A is believed to have a very high substrate specificity whereas CYP7B is active toward oxysterols, dehydroepiandrosterone, and pregnenolone. In the present study, 7 alpha-hydroxylation of various oxysterols in liver and kidney was investigated. Surprisingly, human cholesterol 7 alpha-hydroxylase, CYP7A, expressed as a recombinant in Escherichia coli and COS cells, was active toward 20(S)-hydroxycholesterol, 25-hydroxycholesterol, and 27-hydroxycholesterol. This enzyme has previously been thought to be specific for cholesterol and cholestanol. A partially purified and reconstituted cholesterol 7 alpha-hydroxylase enzyme fraction from pig liver showed 7 alpha-hydroxylase activity toward the same oxysterols as metabolized by expressed recombinant human and rat CYP7A. The 7 alpha-hydroxylase activity toward 20(S)-hydroxycholesterol, 25-hydroxycholesterol, and 27-hydroxycholesterol in rat liver was significantly increased by treatment with cholestyramine, an inducer of CYP7A. From the present results it may be concluded that CYP7A is able to function as an oxysterol 7 alpha-hydroxylase, in addition to the previously known human oxysterol 7 alpha-hydroxylase, CYP7B. These findings may have implications for oxysterol-mediated regulation of gene expression and for pathways of bile acid biosynthesis. A possible use of 20(S)-hydroxycholesterol as a marker substrate for CYP7A is proposed.
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| 16. |
- Novakova, Lenka, 1984, et al.
(author)
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Reduced cerebrospinal fluid concentrations of oxysterols in response to natalizumab treatment of relapsing remitting multiple sclerosis.
- 2015
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In: Journal of the Neurological Sciences. - : Elsevier BV. - 0022-510X .- 1878-5883. ; 358:1-2, s. 201-206
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Journal article (peer-reviewed)abstract
- Abstract BACKGROUND: Natalizumab therapy reduces inflammation and degeneration of the CNS in relapsing-remitting multiple sclerosis (RRMS). In cerebrospinal fluid (CSF) the concentration of 24S-hydroxycholesterol (24OHC) reflect neurodegeneration, whereas 27-hydroxycholesterol (27OHC) is dependent on the integrity of the blood-brain barrier (BBB). OBJECTIVE: To measure the impact from natalizumab treatment on 24OHC and 27OHC concentrations in serum and CSF of RRMS. METHODS: In serum and CSF obtained from 31 patients before and following 12 months of natalizumab treatment, 24OHC and 27OHC were analyzed by isotope-dilution mass spectrometry. RESULTS: Natalizumab treatment reduced CSF-24OHC concentrations (p=0.002), CSF-27OHC concentrations (p=0.01) and serum-24OHC concentrations (p=0.029). There was no significant effect of the treatment on serum-27OHC concentrations. Serum concentrations of 24OHC correlated with Symbol Digit Modalities Test scores before (r=0.5, p=0.007) and after natalizumab treatment (r=0.403, p=0.033). CONCLUSIONS: We showed for the first time that natalizumab treatment of RRMS reduced the concentrations of 24- and 27OHC in CSF, indicating reduced neurodegeneration and improved integrity of the BBB, respectively. Our results imply a role for serum 24OHC as a biomarker of cognition (visuo-spatial ability and processing speed) in RRMS.
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| 17. |
- Pettersson, Hanna, et al.
(author)
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Metabolism of a novel side chain modified Delta 8(14)-15-ketosterol, a potential cholesterol lowering drug : 28-hydroxylation by CYP27A1
- 2008
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In: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier BV. - 1388-1981 .- 1879-2618. ; 1781:8, s. 383-390
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Journal article (peer-reviewed)abstract
- The synthetic inhibitors of sterol biosynthesis, 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one and 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one, are of interest as potential cholesterol lowering drugs. Rapid metabolism of synthetic 15-ketosterols may lead to a decrease, or loss, of their potency to affect lipid metabolism. 3beta-Hydroxy-5alpha-cholest-8(14)-en-15-one is reported to be rapidly side chain oxygenated by rat liver mitochondria. In an attempt to reduce this metabolism, the novel side chain modified 15-ketosterol 3beta-Hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one was synthesized. We have examined the metabolism by recombinant human CYP27A1 of this novel side chain modified 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one and compared the rate of metabolism with that of the previously described 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one. Both sterols were found to be efficiently metabolized by recombinant human CYP27A1. None of the two 15-ketosterols was significantly metabolized by microsomal 7alpha-hydroxylation. Interestingly, CYP27A1-mediated product formation was much lower with the side chain modified 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one than with the previously described 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one. A surprising finding was that this novel side chain modified sterol was metabolized mainly in the C-28 position by CYP27A1. The data on 28-hydroxylation by human CYP27A1 provide new insights on the catalytic properties and substrate specificity of this enzyme. The finding that 3beta-hydroxy-24S-methyl-5alpha-cholesta-8(14),22-dien-15-one with a modified side chain is metabolized at a dramatically slower rate than the previously described 15-ketosterol with unmodified side chain may be important for future development of synthetic cholesterol lowering sterols.
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