Bile composition, changes

TIO. Thureborn, E., Human hepatic bile. Composition changes due to altered enterohepatic circulation. Acta Chir. Scand, 303 (Suppl.) (1962). 

Effects of drug treatment on bile composition could be beneficial or deleterious. For example, if biliary cholesterol secretion is increased in conjunction with a decrease or no change in cholesterol absorption, the overall effect may be positive. This result would suggest that reverse cholesterol transport (RCT) is increased by the treatment. This would be a very desirable effect as explained above. Increased bile salt secretion could also be beneficial for similar reasons. On the other hand, decreased biliary cholesterol or bile salt concentrations are cause for concern since either could be indicative of some degree of hepatotoxi-city and/or cholestasis. At the very least, they would indicate decreased RCT and increased CVD risk. As mentioned above, if drug treatment decreases cholesterol absorption independently of effects on biliary lipids, structural alterations of the compound may improve specificity and/or decrease its absorption so its effect is limited to the intestine. 

Excessive secretion of gastric acid, associated with Helicobacter pylori infection, can result in the development of gastric and duodenal ulcers small changes in the composition of bile can result in crystallization of cholesterol as gallstones failure of exocrine pancreatic secretion (as in cystic fibrosis) leads to undernutrition... 

The fed and fasted state may also have significant effects on the absorption or solubility of a compound. Compositions of media that simulate the fed and fasted states can be found in the literature (19) (see also Chapter 5). These media reflect changes in the pH, bile concentrations, and osmolarity after meal intake and therefore have a different composition than that of typical compendial media. They are primarily used to establish in vitro-in vivo correlations during formulation development and to assess potential food effects and are not intended for quality control purposes. For quality control purposes, the substitution of natural surfactants (bile components) with appropriate synthetic surfactants is permitted and encouraged because of the expense of the natural substances and the labor-intensive preparation of the biorelevant media. 

The bile salts and their ability to form mixed micelles is discussed in some detail in order to foster a better understanding of their applications. It is highly important for the electrophoretic characterization of the micellar phase, and therefore for the calculation of the distribution coefficients, to have a thorough understanding of the mode of micelle formation and structural changes achieved by alteration of the surfactant concentration and micelle composition as well as to develop strategies for micelle optimization. 

PO036 Matheson, H. B. and J. A. Story. Di- PO048 etary psylium hydrocolloid and pectin increase bile acid pool size and change bile acid composition in rats. J Nutr 1994 124(8) 1161-1165. PO049... 

Crosignani, A., Podda, M., Battezzati, P.M., Bertoilnl, E., Zuin, M., Watson, D., Setchell, K.D.R. Changes in bile acid composition in patients with primary biliary cirrhosis induced by ursodeoxycholic acid administration. Hepatology 1991 14 1000-1007... 

The most powerful approach to increase a is to change the composition of the mobile phase. If changing the concentration of the components in the mobile phase provides insufficient change, altering the chemical nature of one of the components will often be sufficient. Also, we can produce other a changes by adding mo-bile-phase modifiers to the mobile phase. The shifts in selectivity under certain circumstances have been attributed to the change in mobile-phase composition rather than to the stationary phase. Also, selectivity arises from the combined action of mobile phase and stationary phase. 

The bowel, one of the largest and most metabolically active organs, contains bacteria that may change the chemical composition of the human body. In renal failure the altered bacterial flora cause the accumulation of aliphatic amines in the gut (09, S25). Bacteria transform part of the choline in the gut to trimethylamine, which is reabsorbed and then either oxidized or demethylated to dimethylamine in the liver (S24). Dimethylamine enters the circulation and is excreted in the bile and urine. The trimethylamine and dimethylamine in the exhaled air of uremic patients may contribute to the classic fishy breath, which can be improved by hemodialysis or by gut sterilization with nonabsorbable antibiotics (S23, S25). The overall role of these compounds as uremic toxins, however, remains to be defined. 

Washizu, T., T. Ishida, M. Wshizu, and J. J. Kaneko. 1994. Changes in bile acid composition of semm and gallbladder bile in bile dnct bgated dogs. Journal of Veterinary Medical Science 56 299-303. 

To test this hypothesis, they raised rats, mice, and hamsters on diets deficient in EFA and produced changes in the composition and amounts of fatty acids, bile acids, and cholseterol in liver and bile similar to those found in humans with cholelithiasis. Furthermore, cholesterol gallstones occurred regularly in the mice and hamsters. Linoleic acid, however, which was depressed in the experimental animals, was normal in the human liver biopsy... 

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