{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T13:02:09Z","timestamp":1791896529373,"version":"4.3.4"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"18","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1996,9,3]]},"abstract":"<jats:p>We have investigated whether side chain-hydroxylated cholesterol species are important for elimination of cholesterol from the brain. Plasma concentrations of 24-hydroxycholesterol (24-OH-Chol) in the internal jugular vein and the brachial artery in healthy volunteers were consistent with a net flux of this steroid from the brain into the circulation, corresponding to elimination of approximately 4 mg cholesterol during a 24-h period in adults. Results of experiments with rats exposed to 18O2 were also consistent with a flux of 24-OH-Chol from the brain into the circulation. No other oxysterol measured showed a similar behavior as 24-OH-Chol. These results and the finding that the concentration of 24-OH-Chol was 30- to 1500-fold higher in the brain than in any other organ except the adrenals indicate that the major part of 24-OH-Chol present in the circulation originates from the brain. Both the 24-OH-Chol present in the brain and in the circulation were the 24S-stereoisomer. In contrast to other oxysterols, levels of plasma 24-OH-Chol were found to be markedly dependent upon age. The ratio between 24-OH-Chol and cholesterol in plasma was approximately 5 times higher during the first decade of life than during the sixth decade. There was a high correlation between levels of 24-OH-Chol in plasma and cerebrospinal fluid. It is suggested that the flux of 24-OH-Chol from the brain is important for cholesterol homeostasis in this organ.<\/jats:p>","DOI":"10.1073\/pnas.93.18.9799","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T10:31:39Z","timestamp":1027679499000},"page":"9799-9804","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":606,"title":["Cholesterol homeostasis in human brain: evidence for an age-dependent flux of 24S-hydroxycholesterol from the brain into the circulation."],"prefix":"10.1073","volume":"93","author":[{"given":"D","family":"L\u00fctjohann","sequence":"first","affiliation":[{"name":"Division of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"O","family":"Breuer","sequence":"additional","affiliation":[{"name":"Division of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G","family":"Ahlborg","sequence":"additional","affiliation":[{"name":"Division of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"I","family":"Nennesmo","sequence":"additional","affiliation":[{"name":"Division of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A","family":"Sid\u00e9n","sequence":"additional","affiliation":[{"name":"Division of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"U","family":"Diczfalusy","sequence":"additional","affiliation":[{"name":"Division of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"I","family":"Bj\u00f6rkhem","sequence":"additional","affiliation":[{"name":"Division of Clinical Chemistry, Karolinska Institute, Huddinge University Hospital, Sweden."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1996,9,3]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.93.18.9799","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T14:16:48Z","timestamp":1649859408000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.93.18.9799"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1996,9,3]]},"references-count":0,"journal-issue":{"issue":"18","published-print":{"date-parts":[[1996,9,3]]}},"alternative-id":["10.1073\/pnas.93.18.9799"],"URL":"https:\/\/doi.org\/10.1073\/pnas.93.18.9799","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1996,9,3]]},"assertion":[{"value":"1996-09-03","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}