In an open-label trial, 20 otherwise healthy morbidly obese patients scheduled for bariatric
surgery will be administered 20 mg/kg/day ursodeoxycholic acid for three weeks until the day
before surgery. The maximum dose will be 3 g/day. Twenty other patients will serve as
controls. Serum from days 1 and 21 will be analyzed for routine liver tests, bile acids, a
complete lipid profile including FA and in addition for 7α-hydroxy-4-cholesten-3-one and
fibroblast growth factor 19 (FGF-19), markers for bile acid synthesis its intestinal
stimulation. For the evaluation of insulin resistance and possible pre-diabetes, plasma will
be taken for the estimation of homeostasis model assessment (HOMA) index and oral glucose
tolerance test (OGTT) will be performed at days 1 and 21. At surgery, a liver biopsy (0.5-1
g) and a white adipose tissue (WAT) specimen (1 cm2) will be taken and immediately frozen in
liquid nitrogen for messenger ribonucleic acid (mRNA) and protein preparation for
quantitative real-time polymerase chain reaction (RT-PCR) and Western analysis, respectively,
histopathological Non-alcoholic fatty liver disease (NAFLD) grading, and measuring of hepatic
and white adipose tissue (WAT) lipase activity. In all patients at randomization, abdominal
ultrasound will be performed for the detection of NAFLD and gallstones and a blood sample
will be taken for the analysis of polymorphisms of hepatic lipid synthesis, storage, fatty
acid (FA) oxidation and export genes. Six month after operation, HOMA, OGTT and abdominal
ultrasound will be repeated.