References: Lecithin
Mutat Res. 1994 Mar;320(4):253-9.
In vitro genotoxicity studies of chrysotile asbestos fibers dispersed in simulated pulmonary surfactant.
Lu J, Keane MJ, Ong T, Wallace WE.
West Virginia University, Morgantown.
Micronucleus (MN) formation and sister-chromatid exchange (SCE) assays were performed for asbestos in cultured Chinese hamster lung (V79) cells to determine the effect of surfactant treatment on the genotoxicity of two chrysotile asbestos samples of different fiber lengths. The cells were challenged in vitro with NIEHS intermediate- and short-length chrysotile fibers in both their native state and with surfactant pretreatment. For the surfactant pretreatment, the fibers were incubated in a simulated pulmonary surfactant which was prepared by ultrasonically dispersing dipalmitoyl lecithin (DPL), a primary component of pulmonary surfactant, in minimal essential medium (MEM). Chrysotile asbestos was ultrasonically mixed into the prepared surfactant dispersion or into MEM. V79 cells were exposed to DPL-treated intermediate-length chrysotile (TICA), intermediate-length chrysotile (ICA), DPL-treated short-length chrysotile (TSCA) or short-length chrysotile (SCA) fibers for 48 h. For each treatment, 2000 mononucleated cells were scored for MN formation, and 30 M2 metaphase cells were scored for SCE induction. The results showed that all samples, TICA, ICA, TSCA and SCA, caused significant elevation in the frequency of cells with micronuclei and of cells with two or more nuclei. The increase in micronucleus frequency was greatest in cells challenged with untreated intermediate-length fibers, and was greater for untreated than for DPL-treated short-length fibers. For the short-length fiber samples, DPL surfactant treatment decreased activity for multiple nucleus formation, while DPL treatment did not result in consistent changes in that activity for intermediate-length fibers. Results of SCE assays were either negative or inconclusive. Cells were more viable following TICA and TSCA tha
Biofizika. 2003 Mar-Apr;48(2):240-5.
[Electric capacitance of bilayer lipid membranes from hydrogenated egg lecithin during phase transition from liquid crystalline state to gel]
[Article in Russian]
Anosov AA, Bogatyreva NE, Korepanova EA, Smirnova EIu, Norik VP, Antonov VF.
Sechenov Moscow Medical Academy, Bol'shaya Pirogovskaya ul. 2-6, Moscow, GSP-3, 119992 Russia.
The electrical capacity of planar bilayer lipid membranes (BLM) from natural hydrogenated egg lecithin (HEL) in n-decane at a temperature of phase transition was measured. The temperature of phase transition was determined calorimetrically to be 51 degrees C. The data obtained revealed a phase separation of HEL in BLM into two fractions, one freezing at 42-44 degrees C and one that is converted to a liquid-crystal state at 51-59 degrees C. It was assumed that the first fraction is rich in dipalmitoyl lecithin, and the second fraction is rich in distearoyl lecithin. Freezing and the transition to the liquid-crystal state were accompanied by an increase and decrease in membrane thickness, respectively, in part due to a displacement of the solvent from the torus to the planar part of the bilayer. The displacement of the solvent is explained by changes in the disjoining pressure in BLM, which arises across the lipid bilayer due to van der Waals forces of attraction between water layers on both sides of the BLM.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12723348&dopt=Abstract lecithin
Chem Phys Lipids. 1996 Jan 25;79(1):55-63.
Location of ubiquinone homologues in liposome membranes studied by fluorescence anisotropy of diphenyl-hexatriene and trimethylammonium-diphenyl-hexatriene.
Jemiola-Rzeminska M, Kruk J, Skowronek M, Strzalka K.
Department of Physiology and Biochemistry of Plants, The Jan Zurzycki Institute of Molecular Biology, Jagiellonian University, Krakow, Poland.
The measurements of diphenyl-hexatriene (DPH) and trimethylammonium-diphenyl-hexatriene (TMA-DPH) fluorescence anisotropy in dipalmitoylphosphatidylcholine (DPPC) and egg yolk lecithin (EYL) liposomes containing different concentrations of various ubiquinone (UQ) homologues have been performed. UQ-4 induced the highest DPH anisotropy increase in DPPC liposomes, whereas for higher UQ homologues the anisotropy was lowered with the increase of UQ side-chain length. These differences were less pronounced in EYL liposomes. It was concluded that at a higher content in the membranes (3-4 mol%), the short-chain ubiquinones are arranged parallel to lipid fatty acid chains, whereas long-chain homologues are progressively removed from the lipid acyl chains into the midplane region of the membrane. At the lower (1-2 mol%) concentrations, long-chain quinones seem to be evenly distributed within the membrane, especially in EYL membranes. UQ-10 in EYL liposomes perturbed TMA-DPH to a similar extend as the short-chain ubiquinones indicating that UQ-10 penetrates the interface regions of the membrane where its redox reactions occur. The localization and physical state of UQ-10 in native membranes is discussed.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8907243&dopt=Abstract lecithin
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