title: On the importance of albumin binding for the flux of 7α-hydroxy-3-oxo-4-cholestenoic acid in the brain.
abstract: We confirmed previous findings by a Japanese group that there is an accumulation of 7α-hydroxy-3-oxo-4-cholestenoic acid (7-Hoca) in human subdural hematomas. The accumulation correlated with the time from the bleeding to the sample collection. We present evidence that these accumulations are likely to be caused by the strong affinity of 7-Hoca to albumin and the marked difference between plasma and brain with respect to levels of albumin. In the circulation, 80-90% of 7-Hoca is bound to albumin with a ratio between the steroid acid and albumin of ∼1.4 ng/mg. In cerebrospinal fluid (CSF), the ratio between 7-Hoca and albumin is ∼30 ng/mg. When albumin or hemolyzed blood in a dialysis bag was exposed to CSF, there was a flux of 7-Hoca from CSF to the albumin. We suggest that the major explanation for accumulation of 7-Hoca in subdural hematoma is a flux from the brain into the hematoma due to the high affinity to albumin and the high capacity of 7-Hoca to pass biomembranes. We discuss the possibility that the markedly different ratios between 7-Hoca and albumin in circulation and brain can explain the flux of 7-Hoca from the brain into circulation against a concentration gradient.
authors.affiliation: Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Karolinska Institute, Huddinge, Sweden.|Department of Biochemistry, Faculty of Medicine, University of Khartoum, Khartoum, Sudan.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Saeed
authors.affiliation: Neurocentrum, Karolinska University Hospital Solna, Solna, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Edström
authors.affiliation: Neurocentrum, Karolinska University Hospital Solna, Solna, Sweden.
authors.forename: Irina
authors.initials: I
authors.lastname: Pikuleva
authors.affiliation: Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Karolinska Institute, Huddinge, Sweden.
authors.forename: Gösta
authors.initials: G
authors.lastname: Eggertsen
authors.affiliation: Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Karolinska Institute, Huddinge, Sweden ingemar.bjorkhem@karolinska.se.
authors.forename: Ingemar
authors.initials: I
authors.lastname: Björkhem
mesh_terms: D000418:Albumins / Q000134:cerebrospinal fluid / Q000378:metabolism*; D001647:Bile Acids and Salts / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000378:metabolism* / Q000473:pathology; D001921:Brain / Q000378:metabolism / Q000473:pathology; D002783:Cholestenones / Q000097:blood* / Q000134:cerebrospinal fluid; D002784:Cholesterol / Q000378:metabolism; D005260:Female; D006408:Hematoma, Subdural / Q000097:blood* / Q000134:cerebrospinal fluid / Q000473:pathology; D006470:Hemorrhage / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D011485:Protein Binding
chemical_list: D000418:Albumins; D001647:Bile Acids and Salts; D002783:Cholestenones; C056891:7 alpha-hydroxy-3-oxo-4-cholestenoic acid; D002784:Cholesterol
keywords: blood-brain barrier; brain cholesterol metabolism; steroid acid; subarachnoidal bleeding; subdural hematoma