Lipids mixed micelles

Lipid mixed micelle Inteferon, TNF Hydrophobic binding... 

Irrespective of the physical form of the carotenoid in the plant tissue it needs to be dissolved directly into the bulk lipid phase (emulsion) and then into the mixed micelles formed from the emulsion droplets by the action of lipases and bile. Alternatively it can dissolve directly into the mixed micelles. The micelles then diffuse through the unstirred water layer covering the brush border of the enterocytes and dissociate, and the components are then absorbed. Although lipid absorption at this point is essentially complete, bile salts and sterols (cholesterol) may not be fully absorbed and are not wholly recovered more distally, some being lost into the large intestine. It is not known whether carotenoids incorporated into mixed micelles are fully or only partially absorbed. 

In contrast, the carotenes such as p-carotene and lycopene may position themselves parallel to the membrane surfaces to remain in a more lipophilic environment in the inner cores of the bilayer membranes. To move through an aqueous environment, carotenoids can be incorporated into lipid particles such as mixed micelles in the gut lumen or lipoproteins in the blood circulation and they can also form complexes with proteins with unspecific or specific bindings. 

Levin, G. and Mokady, S., Incorporation of all-trans or 9-cis- 3-carotene into mixed micelles in vitro. Lipids, 30, 177, 1995. 

The absorption of drugs from the rectal [32] cavity has been studied in some detail. Muranishi et al. [34] have shown that a significant increase in the absorption and lymphatic uptake of soluble and colloidal macromolecules can be achieved by pretreating the rectal mucosal membrane with lipid-nonionic surfactant mixed micelles. They found no evidence of serious damage of the mucosal membrane. Davis [30] suggested that the vaginal cavity could be an effective delivery site for certain pharmaceuticals, such as calcitonin, used for the treatment of postmenopausal osteoporosis. 

II Increased extent and possibly rate Large fluid volume in stomach. Solubilization in mixed micelles and dietary lipids... 

The relative concentration of gadolinium can be significantly increased as compared to that achievable with liposomes because the physical stability of the mixed micelles is reached for relatively low amounts of additional lipids and surfactants. It is also worth mentioning that the gadolinium-heads of the complexes embedded in micelles are all exposed to the aqueous phase and can interact directly with the water molecules of the bulk, a situation which is usually not met with liposome systems. 

Triton X-100 has proved to be of great value in the surface dilution modeb for lipolytic enzyme action. In this experimental strategy, the surface concentration of phospholipid in mixed micelles is reduced by the addition of Triton as a neutral diluent, thereby increasing the average distance between phospholipids. This allows one to draw mechanistic inferences about the binding interactions of lipases and phospholipases with their lipid sub-stratesb... 

The fact that for c, no alteration of the electrophoretic properties of the drug was observed leads to the conclusion that the micelle constitution is constant. Any phospholipids or lipids, which form stable and consistent mixed micelles, may be used. 

KP and v can, in contrast to kp, not be determined via the concentration gradient for binary and ternary mixed micelles, because for the calculation of the Nemstian distribution a constant CMC and an almost constant partial molar volume must be assumed. The calculation of aggregation constants of simple bile salt systems based on Eq. (4) yields similar results (Fig. 8b). Assuming the formation of several concurrent complexes, a brutto stability constant can be calculated. For each application of any tenside, suitable markers have to be found. The completeness of dissolution in the micellar phase is, among other parameters, dependent on the pH value and the ionic strength of the counterions. Therefore, the displacement method should be used, which is not dependent on the chemical solubilization properties of markers. For electrophoretic MACE studies, it is advantageous for the micellar constitution (structure of micelle, type of phase micellar or lamellar) to be known for the relevant range of concentrations (surfactant, lipids). 

NA Mazer, GB Benedeck, MC Carey. Quasielastic light-scattering studies of aqueous biliary lipid systems. Mixed micelles formation in bile salt-lecithin solutions. Biochemistry 19 601-615, 1980. 

C. These products of lipid digestion combine to form mixed micelles, which are taken up efficiently by enterocytes. 

A model that is consistent with these observations of the action of trypsin and phospholipase A and with the discontinuities in the All-composition curves (Figures 2 and 3) is one in which the lipid monolayer is not a continuous palisade of uniformly oriented lipid molecules but rather an assembly of surface micelles. In this model, proposed by Colacicco (4, 5), the protein first comes into contact with the lipid molecules at the periphery of the surface micelles and then inserts itself as a unit between them. This is the basis for the generalized nonspecific interaction between lipids and proteins which results in increase of surface pressure. One may thus explain the identical All values obtained with films of lecithin and 80 mole % lactoside by picturing the lecithin molecules outside and the lactoside molecules inside the surface micelles. In this model lecithin prevents the bound lactoside from interacting nonspecifically with globulin and produces the same increase in pressure as with a film of pure lecithin. In the mixed micelle the lactose moiety of the lactoside protrudes into the aqueous subphase. Contact of the protein with these or other nonperipheral regions of the surface micelle would not increase the surface pressure. 

The role of lecithin as an auxiliary lipid in the specific interaction of lactosides with globulin in monolayers is related to two processes complex formation between 3 or 4 molecules of lactoside and each lecithin molecule, and the protection of the lactoside molecules in surface micelles from nonspecific interaction. The location of lecithin at the periphery of the surface micelle would explain why the mixed micelle behaves as lecithin in nonspecific interaction. Lactoside molecules, located in the center of the surface micelle, would be in a position to interact specifically with antibody in the aqueous subphase (5). 

Absorption of lipids contained in a mixed micelle by an intestinal mucosal cell. 

Correct answer = E. Chylomicrons contain a lipid core that is composed of dietary lipid and lipid synthesized in the intestinal mucosal cells. Free fatty acids are esterified primarily to 2-monoacylglycerol. forming triacylglycerol, prior to export from the intestinal mucosal cells in chylomicrons. Mixed micelles are found only in the lumen of the small intestine. 

The products of lipid digestion—free fatty acids, 2-monoacylglycerol, and cholesterol—plus bile salts, form mixed micelles that are able to cross the unstirred water layer on the surface of the brush border membrane. Individual lipids enter the intestinal mucosal cell cytosol. 

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