title: Quantitative detection of free 24S-hydroxycholesterol, and 27-hydroxycholesterol from human serum.
abstract: BACKGROUND
  Cholesterol metabolism is important for the maintenance of myelin and neuronal membranes in the central nervous system. Blood concentrations of the brain specific cholesterol metabolite 24S-hydroxysterol to the peripheral metabolite 27-hydroxycholesterol may be useful surrogate markers for neurodegenerative diseases including Alzheimer's disease, Huntington's disease, HIV-Associated Neurocognitive Disorders, and Multiple Sclerosis. However, current methods to isolate hydroxycholesterols are labor intensive, prone to produce variable extraction efficiencies and do not discriminate between free and esterfied forms of hydroxycholesterols. Since free hydroxycholesterols are the biologically active form of these sterols, separating free from esterfied forms may provide a sensitive measure to identify disease-associated differences in brain sterol metabolism.
  
  
  RESULTS
  We found that average human serum concentrations were 12.3 ± 4.79 ng/ml for free 24(s)-hydroxycholesterol and 17.7 ± 8.5 ng/ml for 27-hydroxycholesterol.
  
  
  CONCLUSIONS
  Serum measurements of these biologically active oxysterols may be useful surrogate measures for brain health in a variety of neurodegenerative conditions.
authors.affiliation: Department of Neurology, Richard T. Johnson Division of Neuroimmunology and Neurological Infections, The Johns Hopkins University School of Medicine, Carnegie 616A, 600 North Wolfe Street, Baltimore, 21287, MD, USA. vbandar2@jhmi.edu.
authors.forename: Veera Venkata Ratnam
authors.initials: VV
authors.lastname: Bandaru
authors.affiliation: Department of Neurology, Richard T. Johnson Division of Neuroimmunology and Neurological Infections, The Johns Hopkins University School of Medicine, Carnegie 616A, 600 North Wolfe Street, Baltimore, 21287, MD, USA. nhaughe1@jhmi.edu.|Department of Psychiatry, Division of Geriatric Psychiatry and Neuropsychiatry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. nhaughe1@jhmi.edu.
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Haughey
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D006801:Humans; D006888:Hydroxycholesterols / Q000097:blood* / Q000737:chemistry; D008297:Male; D013058:Mass Spectrometry / Q000379:methods
chemical_list: D006888:Hydroxycholesterols; C044563:24-hydroxycholesterol; C076996:27-hydroxycholesterol