Bile acids adsorption

Bile acid-binding resins may be used to lower cholesterol in transplant patients, but adequate doses are difficult to achieve without the development of GI adverse effects. Because the absorption of CSA is dependent on the presence of bile in the GI tract, patients should be instructed to separate dosing of bile acid-binding resins and CSA by at least 2 hours. Bile acid-binding resins also should be separated from other immunosuppressants by at least 2 hours to avoid physical adsorption in the GI tract. For transplant patients who have hypertriglyceridemia refractory to dietary intervention, fish oil and fibric acid derivatives are well-tolerated, effective alternatives (see Chap. 21). Fibric acid derivatives are most effective in lowering serum triglyceride concentrations. 

The calcium exchanged form of the purified natural clinoptilolite (NZ) from the Tasajeras deposit, Cuba, is the active ingredient of a drug designed to reduce total blood cholesterol and prevent atherosclerosis. The study of the Ca -NZ - human bile reaction has revealed that it occurs through the adsorption of three major human bile compounds bile acids, phospholipids and bilirubin. The adsorption of phospholipids on the external surface of the clinoptilolite crystals produces a phospholipids-zeolite interface with anionic activity that allows the adsorption of bile acids. 

Cation adsorption appears to be important in the formation of cationic bridges as a mechanism for bile acid, fatty acid and mineral adsorption in the upper intestine (20). The affinity of copper for carboxylic acid groups has been employed in pectin precipitation (10, 21) and in determinations of cation exchange... 

The adsorption of bile salts to lignins is practically complete in about 5 h. When samples of lignin with adsorbed bile acid were separated from the supernatant, suspended in water and shaken for 3 h, 50% of the bile acid was desorbed. 

The mechanism by which the lipolytic products pass from the micellar phase into the mucosal cell is unknown, and an extensive discussion of the possibilities is inappropriate here. Since lipolytic products are extensively absorbed whereas taurine-conjugated bile acids are not absorbed in jejunal perfusion experiments (23), and since exchange rates of lipolytic products between micelles are thought to be quite rapid (78), molecular collision of lipolytic products with the cell membrane, resulting in reversible or partially reversible adsorption, has been proposed as the mechanism of fat absorp-... 

Column adsorption chromatography should be applied when one deals with very crude extracts, such as those obtained from feces, and when a group separation between mono-, di-, and trisubstituted hydroxycholanoic acids is desirable. It may also be used for large-scale purification of a specific bile acid, e.g., in synthetic work. Silicic acid should be used for free bile acids since more active adsorbents may give incomplete recoveries. Methyl ester or methyl ester acetates are usually best separated on aluminum oxide. In... 

Other adsorbents may be useful for specific purposes. Florisil, 100-200 mesh, purified by hydrochloric acid, water, and methanol washings, and subsequently activated for 2-3 hr at 280°C, has been sucessfully used for the separation of cholic and allocholic acids (72). Charcoal has been successfully used to purify bile acids in extracts from rat feces (73). The original publication does not appear to have tempted other workers to use this adsorbent in bile acid purification, but the results seem to justify further systematic tests, especially since it is a rapid procedure compared to the adsorption methods mentioned above. 

Hofman, a. F. Thin-layer adsorption chromatography of free and conjugated bile acids on silicic acid. J. Lipid Res. 3, 127 (1962). 

In 1997 Esumi and Ueno [1] edited a book on the structure-performance relationships in surfactants, in which the authors stress the need to understand the properties and performance of surfactants at various interfaces such as air-liquid, liquid-liquid and solid-liquid. The book has a few chapters on adsorption theories and some information on the microstructure of nonionic surfactants in solution, some modeling aspects of the association and adsorption of surfactants, and several chapters on the particular behavior of specific surfactants (polymeric, gemini, bile acids, and others) in solution. No significant clear guidelines... 

Gorecka, D., Korezak, J., Konieezny, P, Hes, M., and Elaezyk, E. 2005. Adsorption of bile acids by cereal products. Cereal Foods World 50(4) 176-178. 

A similar investigation was carried out by Kfirkela and Kulonen (1959) who partially hydrolyzed elastin by acids, alkalies, and enzymes under varying conditions and fractionated the products by adsorption on alumina and elution with ammonia. They obtained fractions in which the yellow color was enriched and determined the infrared and ultraviolet absorption spectra. They concluded that the yellow pigment was tightly bound to the peptide chain and that it did not appear to be a bile pigment. 

Fontana also published on formic acid and vegetable acids, potash and soda, the analysis of malachite, inflammable air, and bile. His measurements on the densities of gases were important but his most outstanding work was a series of experiments on respiration, the calcination of metals, adsorption of gases by charcoal (see p. 296), the production of inflammable gas from water and heated charcoal, etc., in which, e.g., he showed that the weight remains constant in chemical reactions, and that different gases follow Boyle s law. ... 

This is usually considered to be essentially monolayer adsorption with competition between solvent and solute. The non-electiolytes that have been studied are mainly fatty acids, aromatic acids, esters and other single functionless group compounds plus a great variety of more complex species such as porphyrins, bile pigments, carotenoids, lipoids and dyestuffs. 

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