title: Plasma 27-hydroxycholesterol/cholesterol ratio is increased in low high density lipoprotein-cholesterol healthy subjects.
abstract: Sterol 27-hydroxylase converts cholesterol to 27-hydroxycholesterol (27-OHC) which is widely distributed among tissues and is expressed at high levels in the vascular endothelium and macrophages. There is a continuous flow of this oxysterol from the tissues into the liver, where it is converted to bile acids.
  
  
  OBJECTIVE
  Measure plasma concentrations of 27-OHC in subjects that differ according to their plasma HDL-C concentration.
  
  
  METHODS
  Healthy men presenting low HDL-C (<1.03 mmol/L), n=18 or high HDL-C (>1.55 mmol/L), n=18, BMI<30 kg/m² were recruited after excluding secondary causes that might interfere with their plasma lipid concentrations such as smoking, heavy drinking and diabetes. Blood samples were drawn after a 12h fasting period for the measurement of 27-OHC by the combined GC/MS analysis utilizing deuterium-label internal standards.
  
  
  RESULTS
  The plasma ratio 27-OHC/total cholesterol (median and range nmoL/mmoL) was 50.41 (27.47-116.00) in the High HDL-C subjects and 63.34 (36.46-91.18) in the Low HDL-C subjects (p=0.0258).
  
  
  CONCLUSIONS
  Our data indicate that the production of 27-OHC by extrahepatic tissues and its transport to the liver may represent an alternative pathway for a deficient reverse cholesterol transport system when plasma HDL-C is low.
authors.affiliation: Lipids Laboratory (LIM-10), Endocrinology and Metabolism Division of Hospital das Clinicas, Faculty of Medical Sciences, University of Sao Paulo, Av. Dr. Arnaldo, 455-Room 3305, CEP 01246-00 São Paulo, SP, Brazil. Electronic address: valeriasutti@gmail.com.
authors.forename: Valéria S
authors.initials: VS
authors.lastname: Nunes
authors.forename: Camila C
authors.initials: CC
authors.lastname: Leança
authors.forename: Natália B
authors.initials: NB
authors.lastname: Panzoldo
authors.forename: Eliane
authors.initials: E
authors.lastname: Parra
authors.forename: Vanessa
authors.initials: V
authors.lastname: Zago
authors.forename: Patrícia M
authors.initials: PM
authors.lastname: Cazita
authors.forename: Edna R
authors.initials: ER
authors.lastname: Nakandakare
authors.forename: Eliana C
authors.initials: EC
authors.lastname: de Faria
authors.forename: Eder C R
authors.initials: EC
authors.lastname: Quintão
mesh_terms: D000328:Adult; D000368:Aged; D001692:Biological Transport; D008076:Cholesterol, HDL / Q000097:blood*; D005215:Fasting; D008401:Gas Chromatography-Mass Spectrometry; D064368:Healthy Volunteers; D006801:Humans; D006888:Hydroxycholesterols / Q000097:blood*; D008099:Liver / Q000378:metabolism*; D008297:Male; D008875:Middle Aged
chemical_list: D008076:Cholesterol, HDL; D006888:Hydroxycholesterols; C076996:27-hydroxycholesterol
keywords: 27-Hydroxycholesterol; HDL-C; Human plasma; Reverse cholesterol transport