| 1. |
- Abdel-Khalik, Jonas, et al.
(författare)
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Bile acid biosynthesis in Smith-Lemli-Opitz syndrome bypassing cholesterol: Potential importance of pathway intermediates.
- 2021
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Ingår i: The Journal of steroid biochemistry and molecular biology. - : Elsevier BV. - 1879-1220 .- 0960-0760. ; 206
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Tidskriftsartikel (refereegranskat)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. |
- Daniilidou, Makrina, et al.
(författare)
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Alzheimer's disease biomarker profiling in a memory clinic cohort without common comorbidities.
- 2023
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Ingår i: Brain communications. - 2632-1297. ; 5:5
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease is a multifactorial disorder with large heterogeneity. Comorbidities such as hypertension, hypercholesterolaemia and diabetes are known contributors to disease progression. However, less is known about their mechanistic contribution to Alzheimer's pathology and neurodegeneration. The aim of this study was to investigate the relationship of several biomarkers related to risk mechanisms in Alzheimer's disease with the well-established Alzheimer's disease markers in a memory clinic population without common comorbidities. We investigated 13 molecular markers representing key mechanisms underlying Alzheimer's disease pathogenesis in CSF from memory clinic patients without diagnosed hypertension, hypercholesterolaemia or diabetes nor other neurodegenerative disorders. An analysis of covariance was used to compare biomarker levels between clinical groups. Associations were analysed by linear regression. Two-step cluster analysis was used to determine patient clusters. Two key markers were analysed by immunofluorescence staining in the hippocampus of non-demented control and Alzheimer's disease individuals. CSF samples from a total of 90 participants were included in this study: 30 from patients with subjective cognitive decline (age 62.4 ± 4.38, female 60%), 30 with mild cognitive impairment (age 65.6 ± 7.48, female 50%) and 30 with Alzheimer's disease (age 68.2 ± 7.86, female 50%). Angiotensinogen, thioredoxin-1 and interleukin-15 had the most prominent associations with Alzheimer's disease pathology, synaptic and axonal damage markers. Synaptosomal-associated protein 25kDa and neurofilament light chain were increased in mild cognitive impairment and Alzheimer's disease patients. Grouping biomarkers by biological function showed that inflammatory and survival components were associated with Alzheimer's disease pathology, synaptic dysfunction and axonal damage. Moreover, a vascular/metabolic component was associated with synaptic dysfunction. In the data-driven analysis, two patient clusters were identified: Cluster 1 had increased CSF markers of oxidative stress, vascular pathology and neuroinflammation and was characterized by elevated synaptic and axonal damage, compared with Cluster 2. Clinical groups were evenly distributed between the clusters. An analysis of post-mortem hippocampal tissue showed that compared with non-demented controls, angiotensinogen staining was higher in Alzheimer's disease and co-localized with phosphorylated-tau. The identification of biomarker-driven endophenotypes in cognitive disorder patients further highlights the biological heterogeneity of Alzheimer's disease and the importance of tailored prevention and treatment strategies.
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| 3. |
- Griffiths, William J., et al.
(författare)
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The Cerebrospinal Fluid Profile of Cholesterol Metabolites in Parkinson’s Disease and Their Association With Disease State and Clinical Features
- 2021
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Ingår i: Frontiers in Aging Neuroscience. - : Frontiers Media S.A.. - 1663-4365. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Disordered cholesterol metabolism is linked to neurodegeneration. In this study we investigated the profile of cholesterol metabolites found in the cerebrospinal fluid (CSF) of Parkinson’s disease (PD) patients. When adjustments were made for confounding variables of age and sex, 7α,(25R)26-dihydroxycholesterol and a second oxysterol 7α,x,y-trihydroxycholest-4-en-3-one (7α,x,y-triHCO), whose exact structure is unknown, were found to be significantly elevated in PD CSF. The likely location of the additional hydroxy groups on the second oxysterol are on the sterol side-chain. We found that CSF 7α-hydroxycholesterol levels correlated positively with depression in PD patients, while two presumptively identified cholestenoic acids correlated negatively with depression.
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| 4. |
- Latorre-Leal, María, et al.
(författare)
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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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Ingår i: Science advances. - 2375-2548. ; 10:4
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Wang, Michael L., et al.
(författare)
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Ibrutinib plus Bendamustine and Rituximab in Untreated Mantle-Cell Lymphoma
- 2022
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Ingår i: New England Journal of Medicine. - 0028-4793. ; 386:26, s. 2482-2494
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Ibrutinib, a Bruton's tyrosine kinase inhibitor, may have clinical benefit when administered in combination with bendamustine and rituximab and followed by rituximab maintenance therapy in older patients with untreated mantle-cell lymphoma. METHODS We randomly assigned patients 65 years of age or older to receive ibrutinib (560 mg, administered orally once daily until disease progression or unacceptable toxic effects) or placebo, plus six cycles of bendamustine (90 mg per square meter of body-surface area) and rituximab (375 mg per square meter). Patients with an objective response (complete or partial response) received rituximab maintenance therapy, administered every 8 weeks for up to 12 additional doses. The primary end point was progression-free survival as assessed by the investigators. Overall survival and safety were also assessed. RESULTS Among 523 patients, 261 were randomly assigned to receive ibrutinib and 262 to receive placebo. At a median follow-up of 84.7 months, the median progression-free survival was 80.6 months in the ibrutinib group and 52.9 months in the placebo group (hazard ratio for disease progression or death, 0.75; 95% confidence interval, 0.59 to 0.96; P=0.01). The percentage of patients with a complete response was 65.5% in the ibrutinib group and 57.6% in the placebo group (P=0.06). Overall survival was similar in the two groups. The incidence of grade 3 or 4 adverse events during treatment was 81.5% in the ibrutinib group and 77.3% in the placebo group. CONCLUSIONS Ibrutinib treatment in combination with standard chemoimmunotherapy significantly prolonged progression-free survival. The safety profile of the combined therapy was consistent with the known profiles of the individual drugs.
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| 6. |
- Wang, Yuqin
(författare)
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Protein and lipid interactions of mammalian antibacterial peptides
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gene-encoded antibacterial peptides are multifunctional effector molecules and play an important role in host innate immunity. Upon stimulation, the mature active peptides are released from inactive precursors. Cathelicidins constitute a family of antibacterial peptides, which share a conserved N-terminal cathelin-like region followed by a variable C-terminal antibacterial domain. In addition to its antibacterial activity, LL-37, the only cathelicidin found in human, is cytotoxic at concentrations higher than the bactericidal concentration. An LL-37 binding protein was purified from human plasma and identified as apolipoprotein A-I (apoA-I). A KD value of 0.6-2.4 µM for the interaction between LL-37 and apoA-1 was determined, and this translates to approximately 90% scavenging of LL-37 at physiological apoA-I plasma concentrations. In an inhibition zone assay, apoA-I gave 50 % of the inhibition attained by plasma, and addition of anti-apoA- I IgG to plasma partly restored the LL-37 antibacterial activity. This suggested that apoA-I can modulate the concentration of free LL- 37, thereby preventing cytotoxic effects. Porcine cathelicidin prophenin (PF) and an 18-residue fragment thereof (PF-18) were found in organic extracts of lung tissues and also in a porcine surfactant preparation. Structure analysis by mass spectrometry revealed a mixture of variant forms of prophenin, including 79-residue PF-1, 80-residue PF-2 with N-terminal Gln and 80residue PF-2 with N-terminal pyroglutamic acid. The antibacterial activity of LL-37 and PF were affected by different factors. PF was more active at lower salt concentrations. In the presence of surfactant preparations, the activity of LL-37 and PF-18 against group B stretptoccoci (GBS) were inhibited in a dose-dependent manner, which was likely to be caused by peptide binding to surfactantlipids. From human granulocytes obtained after treatment with granulocyte-colony stimulating factor (G-CSF) and cortisol, several histone fragments were isolated which exhibited activity against B. megateriumin Bm11 Among these, two Cterminal histone H1A fragments were characterised, corresponding to Lys152-Lys222 and Lys167-Lys222, and both were modified by conjugation of the C-terminal carboxyl group of the tripeptide Arg-Gly-Gly to the side chain amino group of Lys222 via an isopeptide bond. The C-terminal tripeptide Arg- Gly-Gly corresponds uniquely to the three C-terminal residues of ubiquitin. This is the first evidence for ubiquitination of histone H1A. The interpretation of the tandem mass spectra leading to characterisation of the histone H1A modification was aided by a knowledge of the gas-phase ion chemistry leading to the proline effect. From studies of proline rich PF it was suggested that cleavage of Pro-Pro and Pro- Xxx amide bonds proceeds with the formation of (protonated) substituted diketopiperazines or cyclic peptides as the N-terminal fragments and (protonated) peptides as the C-terminal fragments.
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| 7. |
- Yutuc, Eylan, et al.
(författare)
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Deep mining of oxysterols and cholestenoic acids in human plasma and cerebrospinal fluid : Quantification using isotope dilution mass spectrometry
- 2021
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 1154
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Tidskriftsartikel (refereegranskat)abstract
- Both plasma and cerebrospinal fluid (CSF) are rich in cholesterol and its metabolites. Here we describe in detail a methodology for the identification and quantification of multiple sterols including oxysterols and sterol-acids found in these fluids. The method is translatable to any laboratory with access to liquid chromatography – tandem mass spectrometry. The method exploits isotope-dilution mass spectrometry for absolute quantification of target metabolites. The method is applicable for semi-quantification of other sterols for which isotope labelled surrogates are not available and approximate quantification of partially identified sterols. Values are reported for non-esterified sterols in the absence of saponification and total sterols following saponification. In this way absolute quantification data is reported for 17 sterols in the NIST SRM 1950 plasma along with semi-quantitative data for 8 additional sterols and approximate quantification for one further sterol. In a pooled (CSF) sample used for internal quality control, absolute quantification was performed on 10 sterols, semi-quantification on 9 sterols and approximate quantification on a further three partially identified sterols. The value of the method is illustrated by confirming the sterol phenotype of a patient suffering from ACOX2 deficiency, a rare disorder of bile acid biosynthesis, and in a plasma sample from a patient suffering from cerebrotendinous xanthomatosis, where cholesterol 27-hydroxylase is deficient.
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