Bile acid content of gallbladder bile and stones in type IIb and IV hyperlipoproteinemia

HPLC assay of conjugated bile acids in human fluids using on-line sample pretreatment on a standard isocratic chromatograph

A rapid and simple on-line purification procedure was developed for determining the conjugated bile acids in human fluids by high-performance liquid chromatography (HPLC). Biological samples were diluted and directly injected without further treatment onto a pre-column dry-packed with 40-microns octadecylsilica and installed at the injector loop position. After washing the pre-column with 40% methanol in acetate buffer and then with water, the retained compounds were back-flushed by the mobile phase onto the analytical column during the normal course of chromatography. The method was found to be accurate and reproducible. The levels of conjugated bile acids in serum, duodenal bile and gastric juice from patients with hepatobiliary and gastric diseases were determined by on-line pre-column clean-up and reversed-phase HPLC.

Group separation of free and conjugated bile acids by pre-packed anion-exchange cartridges

A rapid and simple procedure for the group separation of the major free and conjugated bile acids of man is described. After initial extraction with Bond Elut C18 cartridges, the analytes are fractionated into the unconjugated, glycine- and taurine-conjugated forms using disposable Bond Elut SAX columns and methanol-acetate buffer eluents. The method is found to be accurate and reproducible and to afford complete resolution between fractions. Free and conjugated bile acids present in human bile and gastric juice are assayed by high-performance liquid chromatography, after extraction and group separation according to the described procedure.

Simultaneous determination of free and conjugated bile acids in human gastric juice by high-performance liquid chromatography

A high-performance liquid chromatographic procedure has been developed for the simultaneous assay of the major free bile acids and the corresponding glycine and taurine conjugates in man. No preliminary fractionation into the free, glyco- and tauro-conjugated forms was required. An Ultrasphere ODS column with UV detection at 210 nm and methanol-acetate buffer gradient elution were used. The retention volume of the conjugates was dependent on the sodium acetate concentration in the mobile phase. The method is applicable to the quantification of intragastric bile acids with satisfactory sensitivity, selectivity and precision. Unconjugated and conjugated bile acids present in the gastric juice of patients with bile reflux gastritis were determined directly after Sep-Pak C18 cartridge purification.

Prediction of lithogenic character of human bile by a quaternary system

The lithogenic character of human gallbladder bile was investigated by a mathematical model on the basis of a clinical data set. Each bile was described by means of the quaternary system bile salts--phospholipids--free fatty acids--cholesterol. Reporting a set of bile samples on the tetrahedron of concentrations, a clear separation emerged between the control bile, the bile from patients with gallstones, and the bile of subjects with gallbladder dyskinesia. This group was characterized by a largely increased content of free fatty acids.

The possible role of free fatty acids in the pathogenesis of cholesterol gallstones in man

The lipid composition of hepatic and gallbladder bile was examined in 20 patients with cholesterol gallstones and in 20 control subjects. Lipid fractions other than bile salts, phospholipids and cholesterol were found to be present, i.e., sterol esters, non-identified fractions and, above all, free fatty acids. The latter probably originated from biliary phospholipids via activity of phospholipases, present in the gallbladder wall. No significant difference in amount and pattern of free fatty acids and phospholipids was found in hepatic bile between patients with gallstones and controls. On the contrary, we observed relevant differences in the lipid composition of gallbladder bile. In this way, we consider that the bile becomes lithogenic inside the gallbladder as a consequence of release of free fatty acids, particularly if these are constituted by saturated chains. In fact, these can compete with cholesterol in the solubilization in biliary micelles. On the other hand, free fatty acids can be directly toxic for the gallbladder wall and produce a cholecystitis.