References: Lecithin
Biofizika. 1994 Mar-Apr;39(2):323-7.
[The effect of cholesterol and dicetylphosphate on the physical parameters of liposomes]
[Article in Russian]
Bondar' OP, Voziian PA, Danchuk SD, Kurliand DI, Kholodova IuD.
The physical parameters of liposomes from phosphatidylcholine with cholesterol or dicetylphosphate were investigated. The sizes, electrophoretic mobility, surface density charges of these liposomes were estimated. It has been shown that dicetylphosphate, as well as cholesterol increases the thickness of bilayer of the lecithin liposomes and at the same time the area occupied by one lipid molecule has not been changed by dicetylphosphate in contrast to cholesterol.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8193193&dopt=Abstract lecithin
venus.iteb.serpukhov.su
The inverted micellar phase, obtained by treating lecithin and Ca(2+)-DNA complex with chloroform, was used as an intermediate step in the preparation of DNA-Ca(2+)-lecithin complex. DSC analysis demonstrated the involvement of a large fraction of lipid in the interaction with DNA. Freeze-fracture electron microscopy revealed (i) rod-like structures on the hydrophobic fracture surface of membranes and (ii) regular bundles of fibrils with a repeat distance of about 6 nm, which were located free in solution. Similar regular bundles of fibrils were also revealed by staining the samples with uranyl acetate. According to the suggested model, the observed structures are hexagonally packed inverted lipid tubes, with DNA located in their central cores. The possible biological relevance of the capability of Ca(2+)-DNA to initiate polymorphic phase transitions of lecithin is discussed.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8706843&dopt=Abstract lecithin
Biochem Mol Med. 1995 Oct;56(1):52-62.
Cholesterol modulation of transmembrane cation transport systems in human erythrocytes.
Lijnen P, Petrov V.
Department of Molecular and Cardiovascular Research, University of Leuven (KULeuven), Belgium.
The aim of this study was to investigate whether in vitro cholesterol enrichment of human erythrocytes affects transmembrane cation transport systems by changes induced in the membrane microviscosity of these cells. Human erythrocytes in suspension were incubated with cholesterol-lecithin dispersions to obtain an enrichment of their membrane cholesterol. The ouabain-sensitive Na+ efflux, the Na+, Li+(-)countertransport activity, the Na+, K+(-)cotransport activity, the basal transmembrane leakage of Na+ and K+, and the enzymatic activity of ATPases were determined in these cholesterol-rich cells and compared with control cells. Membrane core and surface microviscosity was also measured in the control and cholesterol-enriched cells, using the fluorescent probes, 1,6-diphenyl-1,3,5-hexatriene (DPH) and trimethylammonium (TMA)-DPH, respectively. The cholesterol content of the erythrocytes incubated in the presence of cholesterol-rich dispersions increased gradually over time. A 47% increase membrane cholesterol content was obtained after 16 h of incubation, while no change in the erythrocyte phospholipid content was found. High membrane cholesterol in the human erythrocyte phospholipid content was found. High membrane cholesterol in the human erythrocyte, obtained by in vitro enrichment of the cells with cholesterol-lecithin dispersion, inhibited in intact cell suspensions the ouabain-sensitive Na+ efflux, an estimate of the Na+(-)pump activity, and in isolated erythrocyte membranes the enzymatic activity of Na+, K+(-)ATPase, and Mg2+(-)ATPase. The dissociation constant for internal sodium and the maximal rate of ouabain-sensitive Na+ efflux is decreased in cholesterol-rich erythrocytes compared to control cells. The elevated erythrocyte membrane cholester
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