Lecithin egg yolk

Choline occurs widely in nature and, prepared synthetically, it is available as an article of commerce. Soybean lecithin and egg-yolk lecithin have been used as natural sources of choline for supplementing the diet. Other important natural-food sources include Hver and certain legumes (18—22). 

Fig. 9 Surface modification of cells with ssDNA-PEG-lipid. (a) Real-time monitoring of PEG-lipid incorporation into a supported lipid membrane by SPR. (r) A suspension of small unilamellar vesicles (SUV) of egg yolk lecithin (70 pg/mL) was applied to a CH3-SAM surface. A PEG-lipid solution (100 pg/mL) was then applied, (ii) Three types of PEG-lipids were compared PEG-DMPE (C14), PEG-DPPE (C16), and PEG-DSPE (C18) with acyl chains of 14, 16, and 18 carbons, respectively, (b) Confocal laser scanning microscopic image of an CCRF-CEM cell displays immobilized FITC-oligo(dA)2o hybridized to membrane-incorporated oligo(dT)20-PEG-lipid. (c) SPR sensorigrams of interaction between oligo(dA)2o-urokinase and the oligo (dT)2o-PEG-lipid incorporated into the cell surface, (i) BSA solution was applied to block nonspecific sites on the oligo(dT)20-incorporated substrate, (ii) Oligo(dA)20-urokinase (solid line) or oligo(dT)20-urokinase (dotted line) was applied...

Propofol lOmg/mL Soybean oil, concentrated glycerin, egg yolk lecithin, edetate 19,451.2 852.5... 

In this paper we describe two types of observations on egg-yolk lecithin. We present the results of our study of homeotropically oriented samples of La phases by polarizing optical microscopy. This study provides evidence, amid apparently nonsimilar aspects, of the existence of an elementary typical object which we have interpreted as a dislocation. We also studied thin samples of stained lecithin in the high vacuum of the electron microscope. In addition to the defects that are typical of this type of sample, we observed the same elementary object as in La lecithin. 

The specimens are prepared from a colloidal dispersion of egg-yolk lecithin in excess water. In order to obtain reasonable contrast, the water is doped with lead acetate (approximately 0.25 wt % ). However, we have no idea of the proportion of lead in the final product, which is prepared as follows. A microscope grid is soaked in the solution and then allowed to dry either in air or on its edge on filter paper. The specimen is then introduced into the high vacuum 10"6 torr) of the electron microscope (Philips EM300) and observed at 100 kV with the help of a tilting stage. 

Dimyristoyl- and dipalmitoyllecithin were synthesized by acylation of sn-glycero-3-phosphorylcholine with fatty acid anhydrides as described by Cubero Robles and van den Berg (23). The sn-glycero-3-phosphoryl-choline was prepared by deacylation of egg-yolk lecithin according to... 

In all our linewidth studies the width of the central peak was measured—i.e., the linewidth obeying Equation lib. In Ref. 45 we reported 23Na linewidth studies on a lamellar mesophase containing egg-yolk lecithin. The effect of cholesterol on the linewidth was investigated, and we found that with increasing cholesterol content in the phospholipid bilayers a marked reduction in the linewidth was observed. In accordance with similar investigations for simple soap-alcohol-water lamellar mesophases (42, 43) this is interpreted as a partial release of... 

Kato, A., Y. Ishibashi, and Y. Miyake. 1987. Effect of egg-yolk lecithin on transdermal delivery of bunazosin hydrochloride. J Pharm Pharmacol 39 399. 

Complex II consists of four polypeptide subunits (70,000, 27,000, 13,500, and 7,000 daltons). The two larger subunits are components of succinate dehydrogenase and this enzyme or the entire complex II was directly incorporated into phospholipid vesicles at the high protein lipid ratio of 1 2 (w/w). The phospholipid (egg yolk lecithin) contained a small amount of lipid (d) (Table 6.2 I molecule in 1000) or lipid (e) (Table 6.2 1 in 400). After irradiation the labeling pattern was analyzed directly by SDS-polyacrylamide gel electrophoresis. Presumably the lipids that did not become attached to polypeptides ran at the dye front, although this was not demonstrated. 

Traditional mayonnaise is an 80% oil-in-water emulsion, which may rely on mustard seeds for solid particle stabilization. Two constituents of egg yolk, lecithin and cholesterol, are surfactants, which promote the formation of oil-in-water and water-in-oil emulsions, respectively. The ratio of lecithin to cholesterol in egg yolk favors the water-in-oil type but the final emulsion type formed is due to the action of mustard seed, which favors an oil-in-water emulsion (Petrowski, 1976). 

The FDA has issued a guidance suggesting that animal-derived materials such as egg yolk lecithin, and egg phospholipid) used in drug products, originating from Belgium, France, and the Netherlands between January and June 1999 should be investigated for the presence of dioxin and polychlorinated biphenyls. The contamination in the animal-derived product was probably due to contaminated animal feed. 

For molecular modeling of the lipoproteins, values for the partial specific volumes of the lipoprotein components are required. The partial specific volume of an aqueous egg yolk lecithin suspension is 0.984 ml/g (Hauser and Irons, 1972), and this provides a reasonable approximation for the partial specific volume of the phospholipid occupying the surface monolayer of a lipoprotein. The reciprocal of the density of liquid triolein (Small, 1986) yields its partial specific volume, 1.102 ml/g, and provides a reasonable approximation for triglyceride dissolved in the cholesteryl ester-filled core of the LDL. For cholesterol, the partial specific volume of 1.021 ml/g measured in benzene (Haberland and Reynolds, 1973) has been employed. The value of 0.740 ml/g employed for the partial specific volume of apoBlOO was determined from its amino acid composition (Lee et al., 1987). A value of 0.60 ml/g was used for the partial specific volume of the carbohydrate moiety. One important parameter, the partial specific volume of cholesteryl ester, remains to be determined. As will be shown below, its value is estimated to be 1.058 ml/g. 

Another principal source of lecithin is from an extract of soybeans (CAS [8030-76-0]). Egg yolk lecithin (CAS [93685-90-6]) is also listed in Chemical Abstracts. 

Lipid emulsion formulations of prostaglandin Ej have been used in the treatment of vascular disorders. They exhibit a reduced incidence of side-effects at the site of injection, as does the diazepam lipid emulsion. A soybean emulsion stabilized by egg-yolk lecithin releases the PGEj over a period of 4-16 hours depending on pH (Fig. 7.24). The partition coefficients of PCEj between soybean emulsion and aqueous buffers at 20°C are shovm in Fig. 7.25, explaining why... 

The stmeturai units of liposomes are ainphiphile molecules, mainly phospholipids. Alec Bangham and co-workers observed self-closed lipid structures after they had been dissolved in water [35]. This first observation took place after egg yolk lecithin had been dispersed in water. According to D.D.Lasic and D. Papahadjopoulos, liposomes are self-assembling colloidal particles in which a lipid bilayer encapsulates a fraction of the surrounding medium [36]. 

F and 2H Spectra.—Substituent effects are reported on the 19F n.m.r. of sterol trifluoroacetates.75 2H N.m.r. has been used to study the state of labelled cholesterol in multibilayers of egg yolk lecithin containing digitonin.76... 

Fig. 6.2 Ti me profiles of disappearance of cis fatty acid residues obtained by photolysis of egg yolk lecithin in isopropanol. Conditions ...

Figure 1. Surface pressure (ir)- molecular area (A) isotherms for dibehenoyl lecithin (A), dipalmitoyl lecithin (B), and egg yolk lecithin (C) on phosphate buffer (pH 7,1 = 0.1) at room temperature...

The tt-A curves at room temperature for dibehenoyl, dipalmitoyl, and egg yolk lecithins are shown in Figure 1. The condensed isotherm for dibehenoyl lecithin and the curve for dipalmitoyl lecithin which undergoes a two-dimensional condensation at 5.6 dynes/cm at 20.5 °C are consistent with earlier investigations (15, 17). The fully expanded isotherm for egg yolk lecithin was expected in view of the high level of unsaturation of this lipid. 

The effects of lecithin monolayers on Atr and r at different Cp s are shown in Figures 2 and 3. The lecithin monolayers were spread to initial film pressures (t ) of 10 dynes/cm so that the molecular areas for the dibehenoyl and egg yolk lecithins were about 50 and 88 A2/molecule. When Cp is less than 10 5 %, lecithin monolayers give larger values of Att than are observed at the clean air-water interface. In this region r is probably reduced, but the adsorption of protein is so limited that it approaches the limits of experimental error. However, when 10"5 < Cp < 4 X 10 3 %, the lecithin monolayers cause large reductions in Y and Att, and the condensed dibehenoyl lecithin film has the greater effect. The reduction in T is real and not an artifact caused by the lipid monolayer... 

These calculations suggest that /3-casein and egg yolk lecithin do not mix ideally, but the interaction between them promotes a condensation or non-additivity of molecular areas. Also, tt in the egg lecithin—/3-casein system can be as high as 29 dynes/cm (Figure 4) whereas the maximum pressure exerted by the protein alone is about 22 dynes/cm (Figure 2). Of course, the assumption that the interfacial conformation of the protein is unchanged by the presence of lipid is valid only when is less than the collapse pressure of the pure protein film. Between this point and 29 dynes/cm the protein has probably only partially penetrated. Further information about the nature of the lipid-protein interaction can be gained from the data in Figure 4. 

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