Bile acids Subject

A portion of the primary bile acids in the intestine is subjected to further changes by the activity of the intestinal bacteria. These include deconjugation and 7a-dehydroxylation, which produce the secondary bile acids, deoxycholic acid and hthocholic acid. 

Shortly after his thesis work was accepted, Deulofeu proceeded to the University of Munich, where he worked under Prof. H. Wieland on the structural elucidation of bile acids, a subject that had earned Prof. Wieland the 1927 Nobel prize for Chemistry. Deulofeu s stay in Germany was interrupted by a call from Prof. B. Houssay, who offered him a position as Assistant Professor of Biological Chemistry at the Facultad de Medicina of the Universidad of Buenos Aires, a position that he held until 1948 as a part-time professor. 

The interest in bile acids as potential carcinogens was subject to investigation as early as 1940 when Cook et al. reported in Nature that repeated injection of deoxycholic acid into the flanks of mice could induce tumour formation in mice." Furthermore, Kelsey and Pienta showed that treatment of hamster embryo cells with lithocholic acid could cause cell transformation. ... 

T. Kishida, F. Taguchi, L. Feng, A. Tatsuguchi, J. Sato, S. Fujimori, H. Tachikawa, Y. Tamagawa, Y. Yoshida and M. Kobayashi, Analysis of bile acids in colon residual liquid or fecal material in patients with colorectal neoplasia and control subjects, J. Gastroenterol., 1997, 32, 306. 

Graph 8.12 Proportion of DCA, expressed as a percentage of total serum bile acids, in stone-free control subjects and patients with cholesterol GBS. Data taken from references 40 and 41. 

The statins, lovastatin (L), simvastatin (S), pravastatin (P), fluvastatin (F), cerivastatin, and atorvastatin, inhibit HMG CoA reductase. The active group of L, S, P, and F (or their metabolites) resembles that of the physiological substrate of the enzyme (A). L and S are lactones that are rapidly absorbed by the enteral route, subjected to extensive first-pass extraction in the liver, and there hydrolyzed into active metabolites. P and F represent the active form and, as acids, are actively transported by a specific anion carrier that moves bile acids from blood into liver and also mediates the selective hepatic uptake of the mycotoxin, amanitin (A), Atorvastatin has the longest duration of action. 

B. Sundberg, P. Aman, and H. Anders- HV083 son. Oat beta-glucan increases bile acid excretion and a fiber-rich barley fraction increases cholesterol excretion in ileostomy subjects. Amer J Clin HV084... 

Cholesterol level decrease. The husks and seeds were administered orally to six normal adult males and five adult males with ileostomy and six normal adult males and four adult males with ileostomy, respectively, at a dose of 10 g/day for 3 weeks. The husk had no effect on cholesterol or triglyceride concentrations in either normal or ileostomy subjects. Total and HDL cholesterol concentrations were reduced on average by 6.4 and 9.3%, respectively, in normal group after seed supplementation. No effect on fecal bile acid excretion in the normal subjects was found after both regimens. Ileostomy bile acids were increased (on average 25%) after seed supplementation, whereas no effect on cholesterol concentrations was found. These results suggest that psyllium seed may be more effective than the husk in... 

A. Southgate. The effects of two di- SO084 etary fiber supplements on gastrointestinal transit, stool weight and frequency, and bacterial flora, and fecal bile acids in normal subjects. Me- SO085 tabolism 1977 26(2) 117-128. 

Table 5.4.8 Values of serum bile acids from healthy subjects (adapted from [30])...

Table 5.4.15 Serum bile acid levels of healthy subjects and gallstone patients (adapted from [54]). Ffemale, M male...

Octreotide 100 pg given subcutaneously to five healthy subjects 30 minutes before meals for 7 days increased fecal fat excretion however, steatorrhea occurred in only two cases fecal bile acid excretion fell to about 25% (35)... 

There are several ways pectin could reduce serum cholesterol. In studies with human subjects, fecal excretion of bile acids, fatty acids, and total steroids increased when subjects were fed 15-40 g/day of pectin (58, 63, 64). Since pectin usually lowers serum cholesterol only when cholesterol is present in the diet, it seems that pectin might act by reducing cholesterol absorption. Several groups have found that in rats dietary... 

Ellegard, L., Andersson, H., and Bosaeus, I. 1997. Inulin and oligofructose do not influence the absorption of cholesterol, or the excretion of cholesterol, Ca, Mg, Zn, Fe, or bile acids but increases energy excretion in ileostomy subjects. Eur. J. Clin. Nutr. 51, 1-5. 

The Lipid Research Clinics Coronary Primary Prevention Trial (L16, L17) is a landmark double-blind study in which cholestyramine, a bile acid se-questrant that is not absorbed from the gut, was used to lower plasma cholesterol. The investigators recruited 3806 men, with a Type II hyperlipoproteinemia phenotype and in good health, into the study. All were prescribed a cholesterol-lowering diet. Subjects were randomly assigned to a treatment group (who were prescribed 24 g cholestyramine daily) and a group with similar baseline characteristics who received an inactive placebo. A 19% lower incidence of coronary heart disease over a mean of 7.4 years in... 

The liver requires cholesterol for synthesizing VLDL particles and bile acids. Trigly-ceride-rich VLDL particles are released into the blood and, like the chylomicrons, supply Luellmann, Color Atlas of Pharmacology All rights reserved. Usage subject to terms... 

HMG-CoA reductase is the rate-limiting step of cholesterol biosynthesis, and is subject to complex regulatory controls. A relatively constant level of cholesterol in the body (150-200 mg/dl) is maintained primarily by controlling the level of de novo synthesis. The level of cholesterol synthesis is regulated in part by the dietary intake of cholesterol. Cholesterol from both diet and synthesis is utilised in the formation of membranes and in the synthesis of the steroid hormones and bile acids. The greatest proportion of cholesterol is used in bile acid synthesis. 

W. H.J. (1974) Gastric emptying and secretion of bile acids, cholesterol, and pancreatic enzymes during digestion. Duodenal perfusion studies in healthy subjects. Mayo Clin. Proc. 49, 851-860. 

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