Bile and Intestinal Contents

In a recent study Hofmann et al. (116) studied the bile acid composition of bile from germ-free rabbits. Deproteinized bile was first analyzed by thin-layer chromatography for a tentative identification of the conjugated bile acids. After alkaline hydrolysis and methylation, bile acid methyl esters were analyzed by thin-layer and gas chromatography. Trifluoroacetate esters and trimethylsilyl ethers of methyl cholanoates were run on QF-1 or Hi-Eff-8B columns, respectively. Gas chromatography-mass spectrometry was used for the final identifications. 

For the identification of bile acids in bile from man and different animals, Kuksis (13) and co-workers have used ion-exchange chromatography for the separation of glycine- and taurine-conjugated bile acids. After alkaline hydrolysis, extraction, and methylation, the bile acids were analyzed on SE-30 and QF-1 columns. Tentative identifications were supported by additional gas-liquid chromatographic analysis of methyl ester acetates and methyl ester trifluoroacetates. The latter derivatives were also analyzed on OV-17 columns (117). 

In quantitative studies, Stiehl et al. (91) extracted bile acids from duodenal bile with methanol-acetone and the conjugates were hydrolyzed according to the method of Nair et al. (118). The free bile acids were then separated with thin-layer chromatography and determined spectrophoto-metrically after reaction with a sulfuric acid reagent. 

For analysis of the small amounts of bile acids present in gallstones the stones are pulverized and refluxed in chloroform-methanol, 1 1. After evaporation, three-stage countercurrent distribution, and alkaline hydrolysis, the bile acids are determined by gas-liquid chromatography (119). 

After deproteinization of bile, Turnberg and Anthony-Mote (94) were able to quantitate bile acids directly with a NAD-dependent steroid oxido-reductase from a Pseudomonas strain. The suitable concentration range was 10-80 mg of bile acids per 100 ml. The amounts of individual bile acids could be determined after preparative thin-layer chromatography, either before or after hydrolysis of bile acid conjugates. 

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After intramuscular injection of [ H]OA to mice (25 (tg/kg), the toxin was detected in bile and intestine contents after 1 h, and it showed a pattern of elimination involving biliary excretion and enterohepafic circulation. ... 

Diarrhea is a common problem that is usually self-limiting and of short duration. Increased accumulations of small intestinal and colonic contents are known to be responsible for producing diarrhea. The former may be caused by increased intestinal secretion which may be enterotoxin-induced, eg, cholera and E. col] or hormone and dmg-induced, eg, caffeine, prostaglandins, and laxatives decreased intestinal absorption because of decreased mucosal surface area, mucosal disease, eg, tropical spme, or osmotic deficiency, eg, disaccharidase or lactase deficiency and rapid transit of contents. An increased accumulation of colonic content may be linked to increased colonic secretion owing to hydroxy fatty acid or bile acids, and exudation, eg, inflammatory bowel disease or amebiasis decreased colonic absorption caused by decreased surface area, mucosal disease, and osmotic factors and rapid transit, eg, irritable bowel syndrome. 

Most of the forementioned studies which examined the influence of various dietary fiber on the bioavailability of calcium by human subjects have depended upon the comparative measurements of calcium content of diets and calcium contents of stools and urine. As reviewed by Allen (3), calcium balance studies have distinct limitations relative to accuracy and precision. However, their ease of application and cost, laboratory equipment requirements, and real (or perceived) safety in comparison to available radioactive or stable isotope methods continue to make their use popular. In calcium balance studies, calcium absorption is assumed to be the difference between calcium excretion in the feces and calcium intake. Usually this is expressed as a percent of the calcium intake. This method assumes that all fecal calcium loss is unabsorbed dietary calcium which is, of course, untrue since appreciable amounts of calcium from the body are lost via the intestinal route through the biliary tract. Hence, calcium absorption by this method may underestimate absorption of dietary calcium but is useful for comparative purposes. It has been estimated that bile salts may contribute about 100 g calcium/day to the intestinal calcium contents. Bile salt calcium has been found to be more efficiently absorbed through the intestinal mucosa than is dietary calcium (20) but less so by other investigators (21). 

Fatal. Boron concentrations elevated in bile, intestinal contents, and spleen (9)... 

This paper considers the interaction of monoolein, oleic acid, and sodium oleate with bile salt solution in model systems whose compositions have been chosen to simulate those which may occur in small intestinal content. In addition, the behavior of several monoglyceride analogs has been examined to determine the influence of the type of polar head of the lipid on its dispersion by bile salts. Finally, titration experiments were performed to measure the extent of ionization of oleic acid in such systems. 

Carr, T.P., Wood, K.J., Hassel, C.A., Bahl, R., and Gallaher, D.D. 2003. Raising intestinal contents viscosity leads to greater excretion of neutral steroids but not bile acids in hamsters and rats. Nutr. Res. 23, 91-102. 

Abstract The major enzymatic barrier to the absorption of macromolecules, particularly therapeutic peptides, is the pancreatic enzymes the peptidases, nucleases, lipases and esterases that are secreted in considerable quantities into the intestinal lumen and rapidly hydrolyse macromolecules and lipids. In the case of the peptidases, they work in a co-ordinated fashion, whereby the action of the pancreatic enzymes is augmented by those in the brush borders of the intestinal cells. The sloughing-off of mucosal cells into the lumen also furnishes a mixture of enzymes that are a threat to macromolecules. As the specificity and activity of the enzymes are not always predictable, during pharmaceutical development it is important to test the stability of therapeutic macromolecules, and novel macromolecular-containing or lipid-containing formulations, in the presence of mixtures of pancreatic enzymes and bile salts, or in animal intestinal washouts or ideally, aspirates of human intestinal contents. 

Q10 Loss of the villi and epithelial cells causes failure of absorption of fats and their digestive products from the intestinal lumen, although lipase and bile salt production may be adequate. Large quantities of fat can remain in the intestinal contents to be excreted in the faeces this is steatorrhoea. Faeces with a high fat content float in water and are difficult to flush away. 

Copper and Ceruloplasmin in the Adults. The human body contains approximately 100-150 mg Cu, most of which is located in the liver. An intake of approximately 5 mg/day is suflBcient to maintain copper balance. Less than half of this copper is absorbed but most of it is excreted through the bile (120). Absorption from the gastrointestinal tract depends on several factors, the most important of which is probably the acidity of the intestinal content. A small portion is excreted in the urine. 

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