PubMed · 637644
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C Hines. 1978. Vitamins. Absorption and malabsorption.. https://doi.org/10.1001/archinte.138.4.619
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Cholesterin is excreted into bile together with phospholipids and bile acids, which are essential for the formation of micelles. Cholesterin-supersaturation of the bile and a relative hyposecretion of bile acids, the presence resp. the lack of promotors and inhibitors of nucleation and a reduced gallbladder contractility are the most important factors in the formation of cholesterol stones. For the formation of pigment stones, however, an increase of bilirubin production and infection of the biliary tract are the causative factors.
The cholesterol of gallstones comes from the vesicular rather than the micellar phase of bile. Progress in this field has been limited because conventional analytical methods disturb the distribution of cholesterol between the two phases. The resonance of the cholesterol C6 proton occurs at a chemical shift of 5.4 ppm, to be shown by 2D NMR to be specific for biliary cholesterol, and arises only from the micellar mode. Thus integration of the C6 proton resonance peak area provides a direct non-invasive determination of the cholesterol distribution in human bile.
Hydrophobic peptides were isolated from the phospholipid fraction of human bile, plasma and spleen by exclusion chromatography in organic solvents. From plasma, the activation peptide of C1 protease inhibitor was recovered, from spleen the activation peptide of alpha 1-antitrypsin, and from bile, both these peptides, as well as a fragment generated by proteolytic cleavage of alpha 1-antitrypsin six residues N-terminal of the P1-P1' peptide bond. Cleavages in this region inactivate antiproteases but have previously not been reported to occur in vivo. These peptides in human bile may reflect physiological actions in regulation of antiproteolytic activity or bile secretion processes, and/or be of importance for the physicochemical state of cholesterol, phospholipids and bile acids in bile.