Adult friend fineder
In humans, such pre β particles have not yet been identified, and one of the aims of this study is to identify such precursor particles and the factors that may remodel them.These small particles are likely candidates for participating in the process of “reverse cholesterol transport” as has been suggested for the interstitial fluid lipoproteins. (19) have demonstrated a unique profile of HDL generation and cholesterol efflux from rat astrocytes, whereby cholesterol-rich (apo E-HDL) and cholesterol-poor (apo A-I-HDL) are generated.Other reports show that a reduction in brain tissue membrane lipids (gangliosides, phospholipids, and cholesterol) is correlated with reduced synaptic function in patients with early onset form (EOAD) Alzheimer's disease, independent of the β amyloid depositions (17).Apo E and apo A-I are the major CSF apolipoproteins, which are present in high density lipoproteins (HDL), while apo B-containing very low or low density lipoproteins (VLDL or LDL) were never identified in CSF. (4) and later reports by Borghini et al (10) suggest that apo E-enriched HDL is the predominant lipoprotein in CSF.In order to understand how the HDL particles in the brain compartment are synthesized and remodeled, we investigated in human CSF the presence of minor lipoprotein subclasses such as preβ particles by bi-dimensional non-denaturing gel electrophoresis.The physiological role of CSF lipoproteins as substrates for lipolytic enzymes such as lecithin:cholesterol acyltransferase (LCAT), and for lipid transfer proteins such as cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) was investigated.
HDL density range, while apo A-IV was not associated with lipoproteins but appeared in a lipid-free form, co-localizing with LCAT immunoreactivity. This cholesterol could then be removed from the CSF via arachnoid granulations or by redistribution to other cells in the brain compartment (9).
It is not known in what form HDL precursors are synthesized in the brain and whether remodeling occurs within the CSF.
HDL remodeling in the circulation is largely mediated by the enzyme lecithin:cholesterol acyltransferase (LCAT) and the lipid transfer proteins cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP), but in the brain these pathways remain largely obscure.
Several observations suggest a close relationship between the lipoprotein metabolism in the brain and the development of Alzheimer's disease (AD) (1, 2).
Characterization and functional studies of lipoproteins, lipid transfer proteins, and lecithin:cholesterol acyltransferase in CSF of normal individuals and patients with Alzheimer's disease.
Apo E plays an important role in the cholesterol metabolism, both in the peripheral circulation and in the brain, where it is synthesized by astrocytes and glial cells.