Bile acids characteristics

Table 1.1 lists some of the characteristics of the more common bile acids, which are divided into 3 main classes free bile acids, glycine and taurine conjugates. 

Steroids are relatively apolar (hydrophobic). Some polar groups—e.g., hydroxyl and 0X0 groups—give them amphipathic properties. This characteristic is especially pronounced with the bile acids (see p.314). 

Bile acids are synthesized from cholesterol in the liver (see p.314). Their structures can therefore be derived from that of cholesterol. Characteristic for the bile acids is a side chain shortened by three C atoms in which the last carbon atom is oxidized to a carboxyl group. The double bond in ring B is reduced and rings... 

Dietary fiber has a pronounced effect on the characteristics of the fecal mass and on the rate of passage of digest through the G1 trad, High fiber diets also play a role in the excretion of bile acids and cholesterol. 

CHARACTERISTIC STRUCTURES OF BILE ACID DERIVATIVES 2.1 Unique Molecular Structures... 

Fish provide numerous examples of other chemically mediated social behaviors. A dramatic example is the ability of many fish to home or return to a particular geographic location, most typically the site of their nativity. The chemical signals used in homing behavior have not been comprehensively identified but are thought to include both molecules of plant origin that are characteristic of the natal site as well as odorants, including bile acids, that derive from conspecific fish.136137... 

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 derivatives were said to be more stable than TMS ethers so that losses in the column were avoided. The ECD response did not differ much from that of the FID and hence the significance of these derivatives is mainly that they can be better separated from interfering components and used for identification. The derivatives have been used for the analysis of methyl esters of bile acids [334] and androstane in urine [335], They also proved useful in combination with mass spectrometry [336,337] as they provided characteristic mass spectra. 

Manganous chloride-sulphuric acid is a useful spray reagent for t.l.c. of sterols and bile acids, giving characteristic colours. A simple technique for thin-layer... 

It is clear that the presence of bile salts in the G1 tract can alter drug ab-sorptiou iu mauy different ways. Bile salts may increase the total solubility of the drug compouud iu the GI lumen, possibly decrease the free concentration of the drug by micellar encapsulation or modulate the trausport characteristics of compouuds that are actively transported by the ileal bile acid transporter or by other transporters, such as P-gp (Ingels et al., 2002). 

The Development and Characteristics of Radioimmunoassays Used to Measure Bile Acids in Serum... 

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