Cholesterol emulsification

Prepare a 5mg/ml liposome suspension containing a mixture of PC cholesterol PG PDP-PE in molar ratios of 8 10 1 1. The emulsification may be done by any established method (Section 1, this chapter). Suspend the vesicles in 50mM sodium phosphate, 0.15 M NaCl, 10 mM ethylenediamine triacetic acid EDTA, pH 7.2. 

Koseki M, Tsuji K, Nakagawa Y, Kawamura M, Ichikawa T, Kazama M, Kitabatake N and Doi E. 1989. Effects of gum Arabic and pectin on die emulsification, the lipase reaction and die plasma cholesterol... 

Prepare a liposome suspension, containing MPB—PE, at a total lipid concentration of 5 mg/ml in 0.05 M sodium phosphate, 0.15 M NaCl, pH 7.2. Activation of DPPE with SMPB is described in Section 2. A suggested lipid composition for vesicle formation is PC cholesterol PG MPB—PE mixed at a molar ratio of 8 10 1 1. The presence of relatively high levels of cholesterol in the liposomal recipe dramatically enhances the conjugation efficiency of the component MPB—PE groups (Martin et al., 1990). Any method of emulsification to create liposomes of the desired size and morphology may be used (Section 1). 

A special consideration in the digestion of fats is that they are not water soluble and cannot be placed in aqueous solution along with the water-soluble lipase digestive enzymes. However, intimate contact is obtained by emulsification of fats through the action of bile salts from glycocholic and taurocholic acids produced from cholesterol in the liver ... 

Solubilisation (or emnlsification) of dietary lipids is accomplished by means of bile salts, which are synthesised from cholesterol in the liver and then stored in the gallbladder they are emptied into the gnt following the ingestion of fat. Emulsification of dietary fats renders them accessible... 

The fat-soluble vitamins share many properties despite their limited chemical similarity. They are absorbed into the intestinal lymphatics, along with other dietary lipids, after emulsification by bile salts. Lipid malabsorption accompanied by steatorrhea usually results in poor uptake of all the fat-soluble vitamins. Deficiency disease (except in the case of vitamin K) is difficult to produce in adults because large amounts of most fat-soluble vitamins are stored in the liver and in adipose tissue. The fat-soluble vitamins are assembled from isoprenoid units this fact is apparent from examination of the structures of vitamins A, E, and K cholesterol, the precursor of vitamin D, is derived from six isoprenoid units (Chapter 18). Specific biochemical functions for vitamins A, D, and K are known, but a role for vitamin E, other than as a relatively nonspecific antioxidant, remains elusive. 

Bile salt molecules secreted by the gallbladder are essential for the emulsification and absorption of fats. They are the salt forms of bile acids, which are the major product of cholesterol catabolism in the liver. Bile salts form micelles as their hydrophobic face contacts the fat (triacylglycerol), and their polar face maintains contact with the aqueous enviromnent. This micelle formation allows water-soluble digestive enzymes to digest the entrapped triacylglycerol molecnle, releasing fatty acids that are readily absorbed by the digestive system. 

Cholesterol is synthesized from acetyl-CoA in a multistep pathway that occurs primarily in the liver. Small amounts of cholesterol are used to synthesize biologically powerful steroid hormones. Cholesterol is degraded primarily by conversion to the bile salts, which facilitate the emulsification and absorption of dietary fat. 

Steroids are a naturally occurring family of organic molecules of biochemical and medical interest. A great deal of controversy has surrounded various steroids. We worry about the amount of cholesterol in the diet and the possible health effects. We are concerned about the use of anabolic steroids by athletes wishing to build muscle mass and improve their performance. However, members of this family of molecules derived from cholesterol have many important functions in the body. The bile salts that aid in the emulsification and digestion of lipids are steroid molecules, as are the sex hormones testosterone and estrone. 

AcetulanCi. Acetylated lanolin alcohols Prepn-Conrad, Muliuk, J. Soc. Cosmet. Chem. 6, 344 (1955), eidem. LS. pal 2,723.334 (I9S5 to American Cholesterol Prod ) Pale yellow, practically odorless liquid Sp gr at 25 0867 Neutral to litmus. Acid no 0 34 Hydroxyl no. 2.0. Saponification no 190.0 Hydrophobic, practically insol in water with no emulsification. Miscible with mineral oil, castor ml, vegetable oils, isopropanol. 95% ethanol, isopropyl mynstale. isopropyl palmiialc. hutyl stearate l F In cosmetic formulations and shampoo. 

Bile fluid performs two important functions (1) the emulsification, solubilization, and transport of lipids and fat-soluble vitamins by the detergent effects of bile acids, and (2) the elimination of many waste products, including bilirubin and cholesterol secreted via the bile into the gastrointestinal tract. Bile acids and bile salts are the principal components of the bile fluid, acting as detergents in the digestion of fat in the intestinal tract. 

Summary Silicones with substituents from natural sources can be synthesized following simple protocols. The modification can be either hydrophilic, oleophilic or both. As hydrophilic substituents carbohydrates and polyethers are used, as oleophilic substituents cholesterol and simple alkyl chains. The physicochemical properties, such as viscosity, reduction of surface tension and emulsification performance, of silicones with standard modifications and of silicone modifications with substituents fit>m natural sources are significantly different. 

Phospholipids, glycolipids, and cholesterol are the major components of mamalian cell-membrane lipids. They play important roles in cell-signaling transduction and cell-to-cell recognition or modification of enzyme functions. In this study, the TC-CCC system was applied to solve the problem of emulsification, and satisfactory stationary phase retention was obtained. Human brain lipids could then be separated. We established the solvent systems that are used for the separation of most of the phospholipids, glycolipids, and less-polar lipids of the human brain. Furthermore, we demonstrated that molecular species, which are derived from variations of the hydrophobic tail group, were separated by optimizing the composition of the solvents. TC-CCC is available for analyzing the hydrophobicities of various lipid molecules in biomembranes. 

The final emulsification of dietary lipids into micelles (droplets that are small enough to be absorbed across the intestinal mucosa) is achieved by the action of the bile salts. The bile salts are synthesized from cholesterol in the liver, and secreted, together with phospholipids and cholesterol, by the gall bladder. As shown in Figure 4.15, some 2 g of cholesterol and 30 g of bile salts are secreted by the gall bladder each day, almost all of which is reabsorbed, so that the total faecal output of steroids and bile salts is 0.2—1 g/day. 

Excellent agreement with criteria (Eq. (46)) is obtained for experiments performed on medicinal paraffin - water with cholesterol and sodium dodecylsulfate [52]. Ineqs (46) are also the conditions for emulsifications and demulsification. 

Among the most abundant steroids, cholesterol is present in almost all human and animal tissue (Real Life 4-2). Bile acids are produced in the liver as part of a fluid delivered to the duodenum to aid in the emulsification, digestion, and absorption of fats. An example is cholic acid. Cortisone, used extensively in the treatment of rheumatoid inflammations, is one of the adrenocortical hormones produced by the outer part (cortex) of the adrenal glands. These hormones participate in regulating the electrolyte and water balance in the body, as well as in protein and carbohydrate metabolism. 

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