References: Lecithin
J Colloid Interface Sci. 2004 Feb 1;270(1):187-94.
Polymer-induced structural changes in lecithin/sodium dodecyl sulfate-based multilamellar vesicles.
Robertson D, Hellweg T, Tiersch B, Koetz J.
Institut fur Chemie, Universitat Potsdam, Karl-Liebknecht-Str. 24/25, Haus 25, 14476 Golm, Germany.
Aqueous concentrated lecithin mixtures (asolectin from soybean) show typical lamellar liquid crystalline behavior and the individual lamellae tend to form spherical supramolecular structures, i.e., multilamellar vesicles. When part of the lecithin is replaced by the anionic surfactant sodium dodecyl sulfate (SDS), the compact multilamellar vesicles disappear and the viscosity decreases. By adding poly(diallyldimethylammonium chloride) (PDADMAC) to the lecithin/SDS system, the formation of multilamellar vesicles can be induced again and the viscosity increases. However, one characteristic feature of these polymer-modified systems is a temperature-dependent phase transition from a compact multilamellar vesicle phase to a more swollen liquid crystalline phase. The polymer-modified multilamellar compact vesicles are of interest for utilization as new thermosensitive drug delivery systems.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14693151&dopt=Abstract lecithin [PubMed - in process]
Biochemistry. 1992 Oct 6;31(39):9467-72.
Nature of alcohol and anesthetic action on cooperative membrane equilibria.
Janes N, Hsu JW, Rubin E, Taraschi TF.
Department of Pathology and Cell Biology, Jefferson Medical College, Philadelphia, Pennsylvania 19107.
A generalized, colligative thermodynamic framework is used to treat the action of solutes on cooperative membrane equilibria. Configurational entropy, the randomness imparted by solutes through the partitioning or mixing process, is implicated as the energetic driving force for the action of anesthetics on cooperative membrane equilibria. The equilibria predicted to be most sensitive to solute action--in which the dilute solute causes a perturbation equivalent to a large change in temperature--are (1) low-enthalpy processes that coincide with (2) large partitioning differences between states. The model stresses that solutes do not act at a single site, but on both states in an equilibrium, and that the perturbation is determined by the difference in entropy. Evidence for the thermodynamic framework is obtained from the partitioning behavior of the general anesthetic 1-hexanol into a model lecithin (DMPC; 1,2-dimyristoyl-sn-glycero-3-phosphocholine) membrane as a function of temperature and alcohol concentration. The low-enthalpy equilibrium between the gel (L beta') and ripple states (P beta') (pretransition) is more sensitive to 1-hexanol than the high-enthalpy equilibrium between the ripple (P beta') and fluid bilayer states (L alpha) (main transition). The perturbations of both equilibria are accurately described by the colligative thermodynamic framework. The results suggest that alcohols and anesthetics act through entropy to upset the natural thermal balance that maintains native membrane architecture.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1390729&dopt=Abstract lecithin
Cell Mol Biol. 1989;35(1):47-54.
High density lipoproteins during rat liver regeneration.
Bruscalupi G, Dini L, Trentalance A.
Compositional and maturative parameters of high density lipoproteins (HDL) have been examined during the early stages of rat liver regeneration, when lecithin:cholesterol acyltransferase (LCAT) activity, responsible for the maturation of this lipoprotein class, is markedly decreased. Both HDL subclass distribution and chemical composition are not significantly different from the control, except for a slightly lower cholesterol ester content. Few disc-shaped particles are detectable by electron microscopic observation. Cholesterol ester decrease and presence of immature particles are related, but the entity of the modification is lower than suggested by the deep decrease of LCAT activity. This seems to indicate that proper HDL maturation is assured in the regenerating liver despite low LCAT activity.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2706653&dopt=Abstract lecithin
Lecithin online literature
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