Idiotype-anti-idiotype-based noncompetitive enzyme-linked immunosorbent assay of ursodeoxycholic acid 7-N-acetylglucosaminides in human urine with subfemtomole range sensitivity.

We have established a noncompetitive enzyme-linked immunosorbent assay (ELISA) for the group-specific determination of 7-N-acetylglucosaminide of ursodeoxycholic acid (UDCA 7-NAG) and its glycine- and taurine-amidated metabolites (UDCA 7-NAGs) in human urine. These metabolites are expected to be a diagnostic marker for patients with primary biliary cirrhosis (PBC). This assay is based on the idiotype-antiidiotype reaction where the analyte was captured by an excess amount of anti-UDCA 7-NAG antibody, and the unoccupied paratope was blocked with a beta-type antiidiotype antibody. The hapten-occupied antibody was then selectively detected with a biotin-labeled alpha-type antiidiotype antibody. The amount of bound biotin, increasing proportionally to the increase in the analyte, was colorimetrically determined using a peroxidase-labeled streptavidin. This assay provided subfemtomole range sensitivity (detection limit 118 amol) and allowed group-specific measurement of the UDCA 7-NAGs in urine without any pretreatment. The present ELISA revealed that significant amounts of UDCA 7-NAGs are excreted even in healthy subjects. Daily excretion rates for healthy males were determined to be 246+/-184 (S.D.) microg (n=5) as the glycine-amidated UDCA 7-NAG equivalent. Randomly collected urine specimens from patients with PBC (n=7) were also measured, and the assay values (standardized to creatinine excretion) ranged from 1.82 to 13.4 microg/mg Ucre with the average of 5.41+/-4.53 (S.D.) microg/mg Ucre.

Fetal bile acid metabolism: analysis of urinary 3beta-monohydroxy-delta(5) bile acid in preterm infants.

To elucidate the urinary concentration of total bile acids after birth and the profile of the usual and unusual urinary bile acids, especially 3beta-hydroxy-5-cholen-24-oic acid (Delta(5)-3beta-ol), we measured the concentrations of 13 bile acids in the urine from preterm infants vs. full-term controls by gas chromatography-mass spectrometry. The urinary concentration of total bile acids in early preterm infants below 32 weeks of gestational age significantly exceeded that of the late preterm and full-term infants (p < 0.0005). The major urinary bile acids in early preterm infants were cholic acid, 1beta,3alpha,7alpha,12alpha-tetrahydroxy-5beta-cholan-24-oic acid and Delta(5)-3beta-ol. In conclusion, the high urinary concentrations of total bile acids in preterm infants may be due to an overproduction, or more likely to a low hepatic bile acid clearance. An alternative fetal pathway, the acidic pathway, may be a major route of bile acid biosynthesis in preterm infants.

A monoclonal antibody-based enzyme-linked immunosorbent assay of ursodeoxycholic acid 3-sulfates in human urine.

Sulfation of the 3-hydroxy group is assumed to be a major metabolic route of ursodeoxycholic acid (UDCA) which is used for treating various hepatobiliary diseases. We have developed a sensitive enzyme-linked immunosorbent assay (ELISA) for determining the total amount of nonamidated, glycine- and taurine-amidated ursodeoxycholic acid 3-sulfates (UDCA 3-Suls) using a newly established monoclonal antibody. In this study, 12 kinds of antibody-secreting hybridoma clones were generated by a fusion experiment between P3/NS1/1-Ag4-1 myeloma cells and the spleen cells from a BALB/c or an A/J mouse which had been immunized with a conjugate of nonamidated UDCA 3-Sul and bovine serum albumin. One of the monoclonal antibodies, Ba-10 (gamma2a, kappa), had suitable binding properties for clinical application, which was group-specific to the UDCA 3-Suls, and showed negligible cross-reactivities with various related bile acids including potentially interfering compounds, namely, the unconjugated UDCA, UDCA 7-N-acetylglucosaminide, the 3-sulfates of cholic acid, chenodeoxycholic acid and deoxycholic acid. The antibody Ba-10 allowed us to develop a sensitive competitive ELISA system whose measurable range was approximately 2-200 pg per assay. A serial dilution study indicated that the ELISA enables the direct measurement of the UDCA 3-Suls in human urine before and after the administration of exogenous UDCA. The daily urinary excretion rate of UDCA 3-Suls from healthy male volunteers (n = 5) was determined to be a mean of 131 +/- 61.2 (SD) microgram as the nonamidated UDCA 3-Sul equivalent.

Production and characterization of group-specific monoclonal antibodies recognizing nonamidated, glycine- and taurine-amidated ursodeoxycholic acid 7-N-acetylglucosaminides.

Ursodeoxycholic acid 7-N-acetylglucosaminides (UDCA 7-NAGs) are novel conjugated metabolites whose urine levels are expected to be a specific diagnostic index for primary biliary cirrhosis. To obtain a specific antibody which is useful for developing immunochemical analytical methods of UDCA 7-NAGs, a variety of monoclonal antibodies have been generated. Spleen cells from an A/J mouse, which had been immunized with a conjugate of nonamidated UDCA 7-NAG and bovine serum albumin, were fused with P3/NS1/1-Ag4-1 myeloma cells. After screening by an enzyme-linked immunosorbent assay (ELISA) using a beta-galactosidase-labeled antigen, thirteen kinds of antibody-secreting hybridoma clones were established. Binding properties of these monoclonal antibodies were investigated in detail by ELISA. One of these antibodies, Ab-#8 (gamma1, kappa) had the most favorable characteristics for clinical application, which was group-specific to the 7-NAG conjugates of nonamidated, glycine- and taurine-amidated UDCAs providing a highly sensitive dose-response curve for each conjugate (midpoint 17 pg per assay for nonamidated UDCA 7-NAG). Cross-reactivities with eleven kinds of bile acids, including some potential interfering metabolites as UDCA 3-sulfate, were negligibly low. By using direct ELISA based on Ab-#8, daily urinary excretion rates of UDCA 7-NAGs of two healthy subjects were determined to be 1030 and 469 microg as GUDCA 7-NAG equivalent.

Developmental pattern of 3-oxo-delta 4 bile acids in neonatal bile acid metabolism.

AIMS: To investigate whether a fetal pathway of bile acid synthesis persists in neonates and infants. METHODS: 3-oxo-delta 4 bile acids were determined qualitatively and quantitatively in the urine, meconium, and faeces of healthy neonates and infants, using gas chromatography-mass spectrometry. RESULTS: The mean percentage of 3-oxo-delta 4 bile acids in total bile acids in urine at birth was significantly higher than that at 3 or 7 days, and at 1 or 3 months of age. The concentration of this component in meconium was significantly higher than that in faeces at 7 days and at 1 or 3 months of age. CONCLUSIONS: The presence of large amounts of urinary 3-oxo-delta 4 bile acids may indicate immaturity in the activity of hepatic 3-oxo-delta 4-steroid 5 beta-reductase in the first week of postnatal life. Large amounts of this component in meconium may be due to the ingestion of amniotic fluid by the fetus during pregnancy.

Ursocholic acid, a hydrophilic bile acid, fails to improve liver function parameters in primary biliary cirrhosis: comparison with ursodeoxycholic acid.

OBJECTIVE: To compare the effect of short term feeding of ursocholic acid, a hydrophilic bile acid, as the unconjugated acid and the taurine conjugate, on clinical and biochemical features and bile acid metabolism with that of ursodeoxycholic acid in four patients with primary biliary cirrhosis. METHODS: Four patients with stage II primary biliary cirrhosis were studied. Two were fed ursocholic acid (900 mg/day), and two were given tauroursocholate (900 mg/day) in three divided doses. After 1 month, all patients were given 900 mg/day of ursodeoxycholic acid. Fasting serum, bile, and 24-hour urine levels were measured before and at the end of ursocholic acid and tauroursocholate feeding and after 1 month of ursodeoxycholic acid feeding. Clinical and biochemical symptoms were measured by routine hospital methods, and bile acids were measured by gas-liquid chromatography. RESULTS: One month of ursocholic acid or tauroursocholate feeding did not improve clinical or biochemical findings in any patient. Approximately 21-25% ursocholic acid was present in the serum and bile, with substantial metabolism to deoxycholic acid. Increased ursocholic acid was excreted in the urine. In comparison, ursodeoxycholic acid improved biochemical parameters and was 45-65% enriched in the serum and bile. CONCLUSION: Ursocholic acid as the free bile acid or as taurine conjugate, although more hydrophilic, is poorly enriched in serum and bile and is ineffective in patients with primary biliary cirrhosis.

Conjugation types of 7 beta-hydroxylated bile acids detected in healthy human urine.

Bile acids extracted from the urine of a healthy volunteer who excreted 7 beta-hydroxylated bile acids were fractionated to nonamidated, glycine-conjugated, taurine-conjugated, and sulfated bile acid fractions. The chemical conjugation types of the 7 beta-hydroxylated bile acids were then determined by treatment with several enzymes and by capillary column gas chromatography. Large amounts of 3 alpha,7 beta,12 alpha-trihydroxycholanoic acid were present as nonamidated and nonconjugated bile acids, while 3 beta,7 beta-dihydroxycholanoic acid formed nonamidated bile acid N-acetylglucosaminide. In addition, ursodeoxycholic acid formed both glycine-conjugated bile acid and glycine-conjugated bile acid N-acetylglucosaminide. Bile acid N-acetylglucosaminides were hydrolyzed by solvolysis.

The major metabolites of ursodeoxycholic acid in human urine are conjugated with N-acetylglucosamine.

Ursodeoxycholic acid (750 mg/day) was administered orally to ten healthy subjects over a period of 10 days; 24 hr urine samples were collected the day before and on the last day of the study. Urinary bile acids were extracted, separated into groups of conjugates and analyzed by gas chromatography-mass spectrometry and fast atom bombardment mass spectrometry. Excretion of ursodeoxycholic acid rose from 70 to 2,915 micrograms/24 h. The highest increase was observed among N-acetylglucosamine conjugates, 90% of which constituted the previously unknown double conjugate of ursodeoxycholic acid with N-acetylglucosamine and glycine. Excretion of isoursodeoxycholic acid increased from 50 to 738 micrograms/24 h. This isomerization product of ursodeoxycholic acid was excreted almost exclusively as N-acetylglucosamine conjugate. In total, N-acetylglucosamine conjugates constituted 50% of urinary metabolites of ursodeoxycholic acid. In addition, metabolites of ursodeoxycholic acid hydroxylated at carbon atoms 1, 6, 22 and possibly 21 were observed. These compounds were also found as conjugates with N-acetylglucosamine. Their formation from ursodeoxycholic acid was definitely demonstrated by 13C-labeling after giving [24-13C]ursodeoxycholic acid to one of the healthy subjects and to a patient with extrahepatic cholestasis in whom hydroxylation of ursodeoxycholic acid at C-23 was also observed. The patient was also found to excrete the double conjugate of ursodeoxycholic acid with N-acetylglucosamine and taurine. The N-acetylglucosaminidation of ursodeoxycholic acid in vivo was shown to occur at C-7.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of different formula feeds on the developmental pattern of urinary bile acid excretion in infants.

The excretion of bile acids in urine was followed prospectively during the first year of life in 17 infants fed different diets from the age of 3 to 10 days. Eight infants were breast-fed, four were fed formulas that were based on adapted cow's milk, and five were fed a formula that was based on soy protein isolate. The formulas had higher protein concentrations than human milk; had different types of proteins, and had not been supplemented with taurine. Urinary bile acids were determined by gas-liquid chromatographic/mass spectrometric analyses of 24-h urinary samples collected at 1-12 days (only formula-fed infants) and at 1, 3, 6, 9, and 12 months of age. The results showed a higher urinary bile acid excretion at 3 months of age in both formula groups than in the breast-fed infants. A deficiency of dietary taurine during formula-feeding did not seem to limit the formation of taurine conjugates during the first month of life. The developmental pattern of urinary bile acid excretion during the first year differed according to the type of feeding. Isomers of cholic and chenodeoxycholic acid appeared in the urine of all breast-fed infants at 6 to 12 months of age. These metabolites, assumed to be the first metabolites derived from the developing gut flora of the infants, appeared at an earlier age and in higher amounts in both formula groups compared to breast-fed infants. Bile acids lacking a 7-hydroxy group, known to be formed by the intestinal flora, appeared in infants in all feeding groups later than the isomers. The results of the study imply that the early introduction of formula may modify bile acid metabolism in infants.

Biotransformation of orally administered ursodeoxycholic acid in man as observed in gallbladder bile, serum and urine.

The aim of this study was to evaluate the biotransformation of orally administered ursodeoxycholic acid in man. The distribution of ursodeoxycholic acid and its metabolites in gallbladder bile, in serum and in urine with emphasis on separation of their unconjugated, amidated and sulfated species in particular, was investigated. Seven gallstone patients were given 750 mg of ursodeoxycholic acid daily for 2-3 weeks. Six gallstone patients who did not receive ursodeoxycholic acid served as controls. Ursodeoxycholic acid became the major bile acid in gallbladder bile contributing 43% to total bile acids. 2% of biliary ursodeoxycholic acids were in the unconjugated form, 87% in the amidated form and 11% in the sulfated form. Iso-ursodeoxycholic acid was found in bile in small amounts and was present only as the sulfated species and not as the amidated one. Other metabolites of ursodeoxycholic acid tentatively identified in bile were 1 beta, 12 beta, 6 alpha- and 21,22-hydroxylated derivatives of ursodeoxycholic acid. Lithocholic acid in bile tended to increase under ursodeoxycholic acid treatment and was positively correlated to ursodeoxycholic acid. The concentration of cholic acid in bile decreased significantly whereas the levels of deoxycholic acid and chenodeoxycholic acid did not change. Total bile acid concentration in serum and excretion of bile acids in urine increased from 5.4 +/- 1.1 to 18.4 +/- 9.5 mumol l-1 (mean +/- SD, P < 0.005) and from 5.6 +/- 1.3 to 13.1 +/- 7.9 mumol g-1 creatinine (mean +/- SD, P < 0.05) after ursodeoxycholic acid ingestion mainly due to spillover and excretion of ursodeoxycholic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of ursodeoxycholic acid in rat.

The pharmacokinetic behaviour and metabolism of ursodeoxycholic acid (UDCA) have been studied in the rat. After oral administration of both 3H-labelled (4 muCi/kg body wt) and unlabelled (20 mg) UDCA, UDCA appeared in serum almost entirely in conjugated form (taurine conjugated); UDCA was present in bile mostly as taurine conjugated; the more relevant metabolite is 3 alpha,6 alpha, 7 beta-trihydroxycholanoic acid which represents 10% of the total bile acid pool. UDCA increased bile flow and selectively decreased biliary cholesterol secretion, while phospholipid secretion was unaffected. Faecal UDCA excretion was 15-20% while the urinary extraction was 1.5% during 24 h. The data show that UDCA, when administered in high dose, is promptly secreted into bile almost entirely metabolized to tauroursodeoxycholic acid, where it (1) desaturates the cholesterol in bile, (2) exerts choleretic properties.

Characterization of serum and urinary bile acids in patients with primary biliary cirrhosis by gas-liquid chromatography-mass spectrometry: effect of ursodeoxycholic acid treatment.

We have studied the effect of ursodeoxycholic acid on the serum and urinary bile acids in seven patients with moderate to severe primary biliary cirrhosis. Bile acids were characterized by gas-liquid chromatography-mass spectrometry and quantified by capillary gas-liquid chromatography. Serum bile acids were elevated 26-fold over control values, with 2.2 times more cholic acid than chenodeoxycholic acid. Urinary bile acid output was elevated 22-fold over control values with a cholic acid:chenodeoxycholic acid ratio of 1.6. In addition, lithocholic acid, deoxycholic acid, ursodeoxycholic acid, 1 beta-hydroxycholic acid, 1 beta-hydroxydeoxycholic acid, and hyocholic acid were identified in both serum and urine; the proportions of the 1- and 6-hydroxylated bile acids were much higher in urine than in serum of the patients (32.1% versus 4.2%). Three months of placebo administration did not change the serum and urinary bile acid composition. In contrast, ursodeoxycholic acid feeding (12-15 mg/kg body weight per day) for 6 months resulted in a 25% decline in the total serum bile acid concentration from the pretreatment values. The proportion of ursodeoxycholic acid increased from 2.1 to 41.2% of total bile acids, so that total fasting serum endogenous bile acid levels decreased 62.4%. Ursodeoxycholic acid feeding substantially increased urinary bile acid output, with ursodeoxycholic acid comprising 58.1%. The proportion of 1- and 6- hydroxylated endogenous bile acids was reduced by 45.5% from pretreatment levels and approximately 4.5% of the urinary bile acids were omega-muricholic acid, 1 beta-hydroxyursodeoxycholic acid, and 21-hydroxyursodeoxycholic acid. These results demonstrate significant changes in the serum and urinary bile acid pattern in primary biliary cirrhosis during ursodeoxycholic acid treatment. The beneficial effect of ursodeoxycholic acid may be due to reduction of the hydroxylated derivatives of endogenous bile acids together with the appearance of hydroxylated derivatives of ursodeoxycholic acid or it may be due to displacement of the more hydrophobic endogenous bile acids by the hydrophilic ursodeoxycholic acid.

Effect of ursodeoxycholic acid on bile acid metabolism in primary biliary cirrhosis.

We have compared the effect of ursodeoxycholic acid with placebo on the clinical state, blood liver chemistries and serum and urinary bile acids in four patients with primary biliary cirrhosis. All parameters were evaluated monthly, and bile acid composition was measured by capillary gas-liquid chromatography. At the time of admission, all patients showed intense pruritus, and their serum alkaline phosphatase, AST and ALT levels were elevated 4.3, 2.7 and 2.3 times over control values. Serum bile acids were elevated almost 38-fold with 2.5 times more cholic acid than chenodeoxycholic acid. Urinary bile acid output was elevated 28 times the control values, and 36% were 1 beta-hydroxycholic acid, 1 beta-hydroxydeoxycholic acid and hyocholic acid (3 alpha,6 alpha, 7 alpha-trihydroxy-5 beta-cholanoic acid). Three months of placebo administration did not significantly affect the clinical or biochemical presentations, and the serum and urinary bile acid composition did not change. In contrast, ursodeoxycholic acid feeding (12 to 15 mg per kg per day) for 6 months abolished pruritus in two and lessened itching in two subjects and reduced serum alkaline phosphatase, AST and ALT levels by 21, 35 and 47%, respectively. The mean values for the total serum bile acid concentrations in these patients declined 26% from the pretreatment value, but the proportion of ursodeoxycholic acid increased from 3 to 40% of the total bile acids; thus, total fasting serum endogenous bile acid levels decreased almost 50%. Similar changes were noted in the urinary bile acids, in which ursodeoxycholic acid became the major bile acid, and approximately 18% were hydroxylated at C-1, C-6 and C-21.(ABSTRACT TRUNCATED AT 250 WORDS)

N-acetylglucosaminides. A new type of bile acid conjugate in man.

Bile acids were extracted from human urine and were separated into groups of nonamidated and glycine- and taurine-conjugated compounds. Each group was subfractionated in a reversed-phase high performance liquid chromatography system, and the fractions were analyzed by negative ion fast atom bombardment mass spectrometry and also by gas chromatography-mass spectrometry after enzymatic removal of glycine and taurine moieties. The major glycosides of the non-amidated bile acids were more polar than reference bile acid glucosides and gave quasimolecular ions at m/z 592, 594, and 610 consistent with N-acetylglucosaminides of unsaturated dihydroxy and saturated di- and trihydroxy bile acids. Gas chromatography-mass spectrometry analyses of methyl ester trimethylsilyl ether derivatives showed fragments typical for N-acetylglucosaminides (m/z 173 and 186) in addition to those also given by glucosides (m/z 204 and 217). The N-acetylglucosaminides were inert toward alpha- and beta-glucosidase but were cleaved completely with N-acetylglucosaminidase. The released sugar moiety was identified as N-acetylglucosamine. One of the liberated bile acids was identified as ursodeoxycholic acid. The other acids were not identical to any known primary or secondary bile acid in humans. Fast atom bombardment mass spectrometry analyses of the glycine-and taurine-conjugated bile acid glycosides only showed ions consistent with the presence of glucosides (m/z 626 and 676). These compounds were sensitive only toward beta-glucosidase which liberated a trihydroxy bile acid as the major compound. Based on the recover of 13C- and 14C-labeled chenodeoxycholic acid glucoside added as internal standard, the daily excretion of nonamidated bile acid glycosides was estimated to be about 137 micrograms or 0.29 mumol, N-acetylglucosaminides constituting about 90%. The daily excretion of the glucosides of amidated bile acids was about 150 micrograms or 0.25 mumol, glycine conjugates constituting about 90%.

Evidence for bile acid glucosides as normal constituents in human urine.

A glucosyltransferase catalysing formation of bile acid glucosides was recently isolated from human liver microsomes. In order to investigate the potential occurrence of such bile acid derivatives in vivo, a method was devised for their isolation and purification from urine. Conditions were established with the aid of glucosides of radiolabelled, unconjugated glycine and taurine conjugated bile acids prepared enzymatically using human liver microsomes. Analysis by gas chromatography and mass spectrometry of methyl ester trimethylsilyl ether derivatives indicated the excretion of glucosides of nonamidated hyodeoxycholic, chenodeoxycholic, deoxycholic, ursodeoxycholic and cholic acids and of glycine and taurine conjugated chenodeoxycholic and cholic acids. Additional compounds were present giving mass spectral fragmentation patterns typical of di- and trihydroxy bile acid glycosides. Semiquantitative estimates indicated a total daily excretion of about 1 mumol.