Rita Aldini

Enzymatic determination of cholesterol in bile

Abstract A simple, sensitive and rapid method for measuring the cholesterol concentration in bile is described. The method is based on the combination of an enzymatic technique and spectrophotometry. In the present study the results obtained with this method are compared with those obtained by the standard Liebermann-Burchard reaction on the same samples and are found to be in close agreement.

Gallbladder motility in cholesterol gallstone disease: Effect of ursodeoxycholic acid administration and gallstone dissolution

Gallbladder motility was evaluated by ultrasonography in 75 cholesterol gallstone patients and in 77 matched control subjects. All 75 gallstone patients were candidates for oral bile acid therapy (radiolucent gallstones, less than 2 cm in diameter, in well-opacified gallbladder), and 38 of them were also studied during ursodeoxycholic acid administration. An additional 20 gallstone patients were studied 1 year after confirmed gallstone dissolution with oral bile acids. Gallstone patients showed significantly greater fasting and residual volumes, a decreased percent of gallbladder emptying, but a similar absolute emptying and emptying rate compared with the control subjects. Greater fasting volumes and reduced percents of gallbladder emptying were also found in gallstone-free patients who achieved complete dissolution with oral bile acids. After ursodeoxycholic acid administration, fasting gallbladder volumes were greater, and percents of gallbladder emptying were further decreased than in untreated gallstone patients. In conclusion, greater fasting volumes, and not reduced gallbladder contractility, account for the defective gallbladder function in radiolucent (cholesterol-rich) gallstone patients. This condition is likely to precede, and possibly to promote, gallstone formation because it persists after gallstone dissolution. Ursodeoxycholic acid administration worsens the defect observed in gallstone patients. This finding also suggests, although indirectly, that the expected normalization of cholesterol saturation during oral bile acid administration is not paralleled by an improvement in gallbladder function.

Bile acid malabsorption and bile acid diarrhea in intestinal resection.

Bile acid fecal excretion and dihydroxy bile acid concentration in the fecal water of patients with large (N=6) and small (N=8) ileal resection, colectomy (N=5), and healthy controls (N=10) have been studied in order to evaluate the degree of bile acid malabsorption and the occurrence of bile acid diarrhea in intestinal resections of different extent. Bile acid malabsorption was severe in large ileal resections, mild in small ones, and slight in colectomy. The fecal pH seems to be a limiting factor in the occurrence of a bile acid diarrhea, playing a critical role in determining the dihydroxy bile acid solubility in the fecal water. These results seem to suggest that the bile acids may induce water secretion in the colon not only in small but also in large ileal resections.

Effect of ursodeoxycholic acid administration on biliary lipid composition and bile acid kinetics in cholesterol gallstone patients

The effect of ursodeoxycholic acid (UDCA) on bile lipid composition and bile acid kinetics was evaluated in seven cholesterol gallstone patients following one month of UDCA administration (12 mg/kg/day). UDCA administration induces a significant reduction in the cholesterol saturation index (SI). After UDCA treatment, UDCA becomes the predominant biliary bile acid while chenodeoxycholic, cholic, and deoxycholic acid are significantly reduced. UDCA pool significantly increases, and chenodeoxycholic, cholic, and total bile acid pools significantly decrease. The reduction in bile lithogenicity during UDCA administration suggests that UDCA may be useful for cholesterol gallstone treatment in man.

Ursodeoxycholic acid administration on bile acid metabolism in patients with early stages of primary biliary cirrhosis.

Ursodeoxycholic acid has been proposed for the treatment of primary biliary cirrhosis. The aim of this study was to evaluate the effect of ursodeoxycholic acid administration on bile acid metabolism in patients with early-stage primary biliary cirrhosis. Biliary bile acid composition, primary bile acid pool sizes, synthesis, and fractional turnover rate were measured before and after four weeks of ursodeoxycholic acid administration (600 mg/day) in nine patients with biopsy-proven primary biliary cirrhosis (stages I-III). Molar percentages of chenodeoxycholic, cholic, and deoxycholic acids in bile were significantly decreased by ursodeoxycholic acid administration, while its biliary concentration increased to 34.2% at the end of the same four-week period. The cholic and chenodeoxycholic acid pools decreased, although not significantly, while the deoxycholic acid pool was reduced by 60% (from 0.7±0.12 to 0.29±0.07 mmol,P<0.002). Primary bile acid synthesis was slightly increased, and fractional turnover rate was significantly increased. The conversion rate of cholic to deoxycholic acid was measured and found to be significantly increased (P<0.05) after ursodeoxycholic acid administration; however, serum levels of both free and conjugated deoxycholic acid were significantly decreased (from 23.2±9.7 to 3.8±1.9 μmol/liter,P<0.001). We conclude that in patients with primary biliary cirrhosis, ursodeoxycholic acid administration replaces endogenous bile acids in the enterophepatic circulation by increasing bile acid fractional turnover rate without significant increments of their hepatic synthesis.

Liver, pancreas, and biliary tractGallbladder motility in cholesterol gallstone disease: Effect of ursodeoxycholic acid administration and gallstone dissolution

Gallbladder motility was evaluated by ultrasonography in 75 cholesterol gallstone patients and in 77 matched control subjects. All 75 gallstone patients were candidates for oral bile acid therapy (radiolucent gallstones, less than 2 cm in diameter, in well-opacified gallbladder), and 38 of them were also studied during ursodeoxycholic acid administration. An additional 20 gallstone patients were studied 1 year after confirmed gallstone dissolution with oral bile acids. Gallstone patients showed significantly greater fasting and residual volumes, a decreased percent of gallbladder emptying, but a similar absolute emptying and emptying rate compared with the control subjects. Greater fasting volumes and reduced percents of gallbladder emptying were also found in gallstone-free patients who achieved complete dissolution with oral bile acids. After ursodeoxycholic acid administration, fasting gallbladder volumes were greater, and percents of gallbladder emptying were further decreased than in untreated gallstone patients. In conclusion, greater fasting volumes, and not reduced gallbladder contractility, account for the defective gallbladder function in radiolucent (cholesterol-rich) gallstone patients. This condition is likely to precede, and possibly to promote, gallstone formation because it persists after gallstone dissolution. Ursodeoxycholic acid administration worsens the defect observed in gallstone patients. This finding also suggests, although indirectly, that the expected normalization of cholesterol saturation during oral bile acid administration is not paralleled by an improvement in gallbladder function.

Relationship between structure and intestinal absorption of bile acids with a steroid or side-chain modification

UNLABELLED A structure-activity relationship for bile acid (BA) intestinal absorption is known to exist. To better understand the BA structural requirements for optimal BA intestinal absorption, rabbit ileal perfusion studies were performed. Unconjugated BA: Ursodeoxycholic (UDCA) and ursocholic acid (UCA) with methyl (6MUDCA and 6MUCA) or fluoro group (6FUDCA and 6FUCA) in the 6 position and UCA with a methyl group in 23 position (23MUCA) were compared with unconjugated UDCA, UCA, deoxycholic (DCA), chenodeoxycholic (CDCA), hyocholic (HCA), and hyodeoxycholic (HDCA) acid. BA lipophilicity was evaluated by their octanol-water partition coefficient. Conjugated BA: Taurine-conjugated UDCA and UCA with a methyl group in the 23 position (T23MUDCA and T23MUCA) were compared with the corresponding taurine-conjugated natural analogs. An analog of glycine-conjugated UDCA with the C24 amide bond replaced by a -CO-CH2- in the 24 position (24PUDCA) was studied and results were compared with the natural form (GUDCA). Unconjugated BA absorption was dose dependent (i.e., passive) and followed their lipophilicity: DCA > 6MUDCA > CDCA > HDCA > UDCA > HCA > 6FUDCA > 6MUCA > 6FUCA > UCA. Conjugated BA absorption was active, and Vmax was in the following order: TCA > TUDCA > TUCA > T23MUCA > T23MUDCA > 24PUDCA > GUDCA. 24PUDCA transport was also active and higher than GUDCA. CONCLUSION Passive transport is dependent on BA lipophilicity. Conjugated BAs are actively transported, and the presence of a 23-C methyl group does not improve transport when compared with the natural analogs. The substitution of the C24 amide bond with a -CO-CH2-still affords interaction of the BA with the intestinal transport carrier.

Antiinflammatory effect of phytosterols in experimental murine colitis model: prevention, induction, remission study.

Phytosterols, besides hypocholesterolemic effect, present anti-inflammatory properties. Little information is available about their efficacy in Inflammatory Bowel Disease (IBD). Therefore, we have evaluated the effect of a mixture of phytosterols on prevention/induction/remission in a murine experimental model of colitis. Phytosterols were administered x os before, during and after colitis induction with Dextran Sodium Sulfate (DSS) in mice. Disease Activity Index (DAI), colon length, histopathology score, 18F-FDG microPET, oxidative stress in the intestinal tissue (ileum and colon) and gallbladder ileum and colon spontaneous and carbachol (CCh) induced motility, plasma lipids and plasma, liver and biliary bile acids (BA) were evaluated. A similar longitudinal study was performed in a DSS colitis control group. Mice treated with DSS developed severe colitis as shown by DAI, colon length, histopathology score, 18F-FDG microPET, oxidative stress. Both spontaneous and induced ileal and colonic motility were severely disturbed. The same was observed with gallbladder. DSS colitis resulted in an increase in plasma cholesterol, and a modification of the BA pattern. Phytosterols feeding did not prevent colitis onset but significantly reduced the severity of the disease and improved clinical and histological remission. It had strong antioxidant effects, almost restored colon, ileal and gallbladder motility. Plasmatic levels of cholesterol were also reduced. DSS induced a modification in the BA pattern consistent with an increase in the intestinal BA deconjugating bacteria, prevented by phytosterols. Phytosterols seem a potential nutraceutical tool for gastrointestinal inflammatory diseases, combining metabolic systematic and local anti-inflammatory effects.

Bile acid active and passive ileal transport in the rabbit: effect of luminal stirring

Abstract. The intestinal absorption of bile acids (BA) with different chemical structure has been evaluated in the rabbit, after intestinal infusion of different concentrations (025–30 mM) of BA, by mesenteric blood sampling. Cholic (CA), chenodeoxycholic (CDCA), ursodeoxycholic (UDCA) acid, free and taurine (T‐) conjugated, together with glycocholic (GCA) acid and deoxycholic acid (DCA) were studied.

Effect of ursodeoxycholic acid administration on biliary lipid secretion in primary biliary cirrhosis.

Ursodeoxycholic acid (UDCA) has been reported to improve liver function tests when administered to patients with cholestatic liver diseases, such as primary biliary cirrhosis (PBC). However, its effects on biliary lipid metabolism in patients with PBC are still unknown. In this study we report the effect that UDCA (600 mg/day, for four weeks) had on biliary cholesterol saturation index, biliary bile acid pattern and pool size, and biliary lipid output in seven female patients (ages 34–58 years) with PBC, stages I to III. A significant improvement of liver function tests was observed after four weeks of treatment. Saturation index was significantly decreased from 1.23±0.1 to 0.7±0.08 (P<0.02); this effect was due to the significant decrease of biliary cholesterol concentration from 6.7±0.36 to 3.6±0.37 percent molar (P<0.02). A significant decrease of cholesterol output (from 88±9 to 55±10 μmol/hr, P<0.02) was also observed. The amount of cholic acid, the predominant bile acid in bile, significantly decreased (from 47.3±3.5 to 35.4±2.6 percent molar, P<0.02), as did amounts of chenodeoxycholic and deoxycholic acids, while the amount of UDCA rose from 1.6±1.0 to 34.0±1.3 percent molar (P<0.02). Total bile acid pool size was not affected by UDCA, but the evaluation of individual bile acid pool sizes showed an increased proportion of UDCA relative to the endogenous bile acids. The results of the study confirm the beneficial effect of UDCA on liver function tests in PBC patients and support the hypothesis that the improvement of these measurements may be due to replacement of toxic endogenous bile acids with UDCA.