Na+-dependent bile acid transport in the ileum: the balance between diarrhea and constipation.

Ileal Na+-dependent bile acid transport was quantified in vitro as the uptake of 3H-taurocholate into brush-border membrane vesicles. Vesicles were prepared from ileal biopsies of 158 patients placed in 10 diagnostic categories. Active bile acid transport (expressed as picomoles taurocholate uptake per milligram brush-border membrane protein per 15 s, median and interquartile ranges indicated) did not differ significantly in 6 categories: irritable bowel syndrome (71, 35-97; n = 21), colon polyps (42, 30-89; n = 29), colitis (62, 33-91; n = 31), postvagotomy or postcholecystectomy (69, 37-97; n = 11), diarrhea without increased bile acid loss (58, 48-85; n = 12), and lack of gastrointestinal pathology (74, 45-103; n = 22).

[75Se]-selenohomotaurocholic acid degradation by bacterial enzymes in vitro and in vivo. Is it still a specific indicator for active ileal bile acid uptake?

The stability of the bile acid analogue [75Se]-selenohomotaurocholic acid (75SeH-CAT) was studied in man. When 75SeHCAT was administered to patients for diagnostic purposes the majority of labeled material present in the feces was found deconjugated. In vitro incubation of 75SeHCAT, by addition of fecal homogenate or with addition of purified enzyme, showed identical deconjugation.

Bile acid malabsorption in cystic fibrosis; membrane vesicles, a tool for revealing the role of the ileal brush border membrane.

Increased fecal bile acid loss in cystic fibrosis (CF) may result from ileal dysfunction. A method to quantitate in vitro Na+-dependent taurocholate uptake into brush border membrane vesicles prepared from frozen ileum and ileal biopsy specimen is described. This transport across the ileal brush border membrane can be measured selectively, in contrast to in vivo measurements which represent a complex overall process.

Endogenous bile acid tolerance test for liver function.

Fasting and postprandial (stimulated) serum conjugated bile acids (CBA) were measured by a solid-phase radioimmunoassay in 329 patients undergoing liver biopsy, and the results were analyzed for 231 who fitted into 10 diagnostic categories. In healthy volunteers the mean fasting CBA of 1.8 +/- 0.

Solid phase radioimmunoassay for determination of conjugated cholic acid in serum.

A modified radioimmunoassay for conjugated cholates is presented. In this modification the antibody is chemically bound to Sepharose which enablproducibility (the coefficient of variation between samples is 4%). The whole procedure is carried out at room temperature and with a short incubation time (45 min).