Nature of tissue-bound lithocholic acid and its implications in the role of bile acids in carcinogenesis

Lithocholic acid, a monohydroxy secondary bile acid, is present in tissues in two forms. One form is extractable with 95% ethanol-0.1% ammonia (soluble lithocholate), and the other form is firmly bound to tissue residues and can be released only by the bile salt-deconjugating enzyme, clostridial cholanoylamino acid hydrolase (tissue-bound lithocholate). Studies on bile salt-protein interactions revealed that lithocholic acid had amino group-modifying activity specifically directed against the basic side group of lysine residues. Degradative procedures yielded N-epsilon-lithocholyllysine, confirmed by comparison with the authentic compound synthesized in our laboratories. Studies on the distribution of tissue-bound lithocholate in tissues have revealed high concentrations of this form of lithocholate in livers of rats treated with the carcinogen, methylazoxymethanol. In light of these observations, the role of bile acids, and specifically lithocholic acid, as promoters of tumorigenesis must be further investigated.

Quantitative determination of bile acids in bile with reversed-phase high-performance liquid chromatography

Separation and quantitation of glycine and taurine conjugates of commonly occurring bile acids in bile, i.e. lithocholic, deoxycholic, chenodeoxycholic, ursodeoxycholic and cholic acids in their naturally occurring states have been successfully accomplished using high-performance liquid chromatography. No preliminary purification of bile acids is required except ethanol extraction of bile. A muBondapak C18 column and acetonitrile--methanol--phosphate buffer and ultraviolet detector at 200 nm were used. Detection limit weas 0.05 microgram and linearity was observed in the range up to 16 microgram. Bile acid composition of ten randomly chosen normal human gallbladder bile samples is given. A large difference in bile acid composition between glycine and taurine conjugates was found to be present.

Enzymic determination of 3 alpha-, 7 alpha-, and 12 alpha-hydroxyl groups of fecal bile salts

We used microbial 3 alpha, 7 alpha-, and 12 alpha-hydroxysteroid dehydrogenases to quantify 3 alpha-, 7 alpha-, and 12 alpha-hydroxyl groups in human feces. Samples collected over a 48-h period were lyophilized, extracted, and reconstituted by a modification of the method of DeWael et al. (clin. Chim. Acta 79: 465--470, 1977), then quantified enzymically by use of three group-specific hydroxysteroid dehydrogenase preparations. Total values for the three hydroxyl groups are given for 18 healthy humans. The ratio of 3 alpha-OH groups/7 alpha-OH groups/12 alpha-OH groups was 34.4 (SD 5.9)/25.2 (SD 6.4)/40.4 (SD 7.7) for the 18 samples.

Measurement of faecal bile acid sulphates

A method is described for the measurement, by difference, of the sulphate fractions of faecal bile acids. A solvolysis step (for the deliberate hydrolysis of the bile acid sulphates) was added to the procedure of sample homogenisation, extraction, enzymatic hydrolysis and thin-layer chromatography. The bile acids were quantitated by gas-liquid chromatography of their methyl ester and trifluoroacetate methyl ester derivatives on 3% QF-1 columns. The total bile acid excretion in 15 control subjects was 603 +/- 71 mg/24 h (mean +/- S.E.M.). The major bile acid peaks (mg/24 h) were: lithocholic acid, without solvolysis 118 +/- 26 and including solvolysis 175 +/- 30; deoxycholic acid 60 +/- 8 and 90 +/- 18 and chenodeoxycholic acid 13 +/- 7 and 15 +/- 7. It was concluded that bile acid sulphates may form a considerable proportion of the total bile acids excreted in man.

Evaluation of the 3 alpha-hydroxysteroid dehydrogenase assay for ursodeoxycholic acid, and 7 oxo- and 12 oxo- bile acids

3 alpha-Hydroxysteroid dehydrogenase (SDH) quantifies ursodeoxycholic acid, 3 alpha,12 alpha-diol-7-one-5 beta-cholanoic acid, 3 alpha-ol-7-one-5 beta-cholanoic acid, and 3 alpha,7 alpha-diol-12-one-5 beta-cholanoic acid in a manner similar to the more commonly measured bile acids, exemplified by taurocholic acid. The type of oxygen function at the 7 or 12 position and its orientation at the 7 position has no effect on the rate of reaction of the enzyme. Discrepancies in the glycine/taurine ratios of patient intestinal aspirates containing ursodeoxycholic acid and oxo bile acids, obtained by SDH and gas-liquid chromatographic methods are not a result of the enzyme assay procedure.

Effect of coprophagy on bile acid metabolism in the rabbit

The effect of coprophagy on the 7 alpha-dehydroxylation of biliary bile acids was studied in the rabbit. Bile acid composition of bile and intestinal contents was analyzed by gas-liquid chromatography and thin layer chromatography. Biliary bile acid composition of normal rabbits (n = 5) was: deoxycholic acid, 95.3 +/- 1.0SE % and cholic acid, 2.3 +/- 1.1SE %. When coprophagy was prevented, significant alterations were observed in biliary bile acid composition, including a considerable decrease in deoxycholic acid (82.5 +/- 2.8SE %, p less than 0.01) and a marked increase in cholic acid (15.2 +/- 3.0SE %, p less than 0.002). These results indicate that coprophagy is a factor causing an increase of the 7 alpha-dehydroxylated bile acid, deoxycholic acid (and lithocholic acid when the animals were fed chenodeoxycholic acid) in rabbit bile.

Solution properties of sulfated monohydroxy bile salts. Relative insolubility of the disodium salt of glycolithocholate sulfate

Physical-chemical properties of the major sulfated monohydroxy bile salts of man are described. In general, the sulfates are significantly more water-soluble than the non-sulfated species as a result of lower critical micellar temperatures, high aqueous monomeric solubilities and critical micellar concentrations. Nevertheless, at 37 degrees C the disodium salt of glycolithocholate sulfate, the major monohydroxy bile salt of man is not more soluble than its non-sulfated form. Since aqueous solubility correlates inversely with the cholestatic potential of bile salts, our results suggest that this sulfate may be potentially hepatoxic. Micellar solubility of phosphatidylcholine and cholesterol by the majority of non-sulfated and sulfated monohydroxy bile salts is slight. Nonetheless, phosphatidylcholine is very well solubilized by taurolithocholate sulfate but cholesterol solubility is not increased appreciably. Cholesterol saturation in model bile systems of taurochenodeoxycholate and phosphatidylcholine is impaired by the addition of sulfated lithocholate conjugates but with physiological bile salt compositions this reduction is not significant.

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.

Simultaneous determination of biliary cile acids in rat: electron impact and ammonia chemical ionization mass spectrometric analyses of bile acids

Bile acids in the rat bile were fractionated into unconjugated, glycine- and taurine-conjugated fractions by employing piperidino-hydroxypropyl Sephadex LH-20 ion-exchange chromatography. Subsequently, these fractions were analyzed by gas-liquid chromatography (GLC) and GLC-mass spectrometry using a Silicone AN-600 column. Not only lithocholic acid, deoxycholic acid, chenodeoxycholic acid, hyodeoxycholic acid, ursodeoxycholic acid and cholic acid, but also alpha- and beta-muricholic acids were quantitatively and simultaneously detectable in conjugated and unconjugated fractions, respectively. In the unconjugated and conjugated fractions, varying amounts of the unidentified bile acid were detected upon GLC. The electron impact and ammonia chemical ionization mass spectrometric results and catalytic hydrogenation on the compound indicate that this bile acid seems to be a derivative of beta-muricholic acid having a double bond in the side chain. The present method is suitable to the simultaneous and quantitative determination of unconjugated and glycine- and taurine-conjugated bile acids in the rat bile.

A radioimmunoassay for lithocholic acid conjugates in human serum and liver tissue

A sensitive and specific radioimmunoassay for glycine and taurine conjugates of lithocholic acid (CLCA) has been developed. 3H-glycolithocholic acid (S.A. = 17Ci/mmol) was used as tracer. Separation of free from antibody-bound bile acid was carried out using ammonium sulphate (saturated solution). The antiserum showed high specificity for both glyco and tauro conjugated lithocholate (100% cross reaction) and lithocholic acid (25% cross reaction). The sensitivity of the assay (1 pmole/tube), was adequate for measuring CLCA in peripheral blood and hepatic tissue in man.

A rapid, sensitive method for accurate analysis of individual bile acids in biological fluids by high performance thin-layer chromatography and densitometry

1. A rapid new micromethod for quantitative analysis of individual bile acids in duodenal juice by high performance thin-layer chromatography (HPTLC) and densitometry is described and evaluated by comparison with standard TLC and spectrophotometry. 2. Advantages of HPTLC over TLC include more rapid separation, better resolution and more sensitive detection (5 - 10 fold), without the need for prior extraction. Densitometry provides simple, direct and rapid quantitation. 3. The method is accurate and reliable over a range of bile acid concentrations. In the 0.5 mM range, recovery was greater than 89%, and coefficients of variation for within-day analysis were 2 - 12% and for between-day analysis were 6 - 18% for the individual bile acids. Twenty analyses can be performed by one worker in a single day. 4. We conclude that the method offers several advantages over most currently described techniques, is suitable for routine use and is deserving of wider application.

Elevations in skin tissue levels of bile acids in human cholestasis: relation to serum levels and topruritus

To define the relationship of bile acid retention to the pruritus of cholestasis, we quantified individual bile acids in serum, acetone swabs of skin, and skin tissue in 13 patients with cholestasis undergoing laparotomy and in 8 controls. There was no consistent relationship between pruritus and concentrations of either total or individual bile acids in serum. Skin tissue concentrations of bile acids were elevated in patients with cholestasis, were linearly related to serum levels, and did not differentiate between those patients with and those without pruritus. Concentrations of bile acids on the skin surface, which were lower than those reported by others, did not correlate with pruritus, and were decreased by simple soap and water washing. These data indicate that the pruritus of cholestasis is not directly related to the skin tissue concentration of any of the major bile acids, although a relationship to a particular molecular form of bile acids could not be excluded.

Bile acids in liver disease associated with inflammatory bowel disease

To investigate the possibility that bowel-related liver disease is due to accumulation of abnormal bile acids in the enterohepatic circulation, bile acids have been measured in gall-bladder bile and portal blood of patients with chronic bowel disease, none of whom had liver disease. There was no difference in the composition and concentration of bile acids in bile and portal blood compared with control patients. In a second study, serum bile acid composition and concentrations were similar in two groups of patients with liver disease, whether they had bowel disease or not. In a further study, post-prandial serum bile acid concentrations were not elevated in a group of patients with chronic bowel disease, making it unlikely that subcliical liver disease was present. No evidence has been found to support the hypothesis that bowel-related liver disease in man results from the action of abnormal bile acids.

Lithocholate metabolism during chenotherapy for gallstone dissolution. 1. Serum levels of sulphated and unsulphated lithocholates

Serum levels of total sulphated and total unsulphated lithocholates were each measured by a specific radioimmunoassay in 66 patients ingesting chenodeoxycholic (chenic) acid for gallstone dissoultion and in 35 gallstone patients ingesting either cholic acid or placebo. No changes occurred in serum lithocholate levels in the control groups. In patients ingesting chenic acid, there was a twofold increase in serum levels of total lithocholate, but the percent sulphation (greater than 75%) remained unchanged during chenotherapy. There was no correlation in the chenic acid treated group between serum lithocholate levels and the proportion of lithocholate in biliary bile acids or changes in serum SGOT. The data suggest that there is effective sulphation of lithocholate in such patients; this may explain the lack of hepatotoxicity observed during ingestion of chenic acid.

Quantitative analysis of individual bile acids by gas-liquid chromatography: an improved method

The quantitative analysis of individual bile acids by gas-liquid chromatography has been improved by column oven temperature programming and by a new liquid phase, SP-2401. The method is fast; bile acids are well resolved; retention times are reproducible; detector responses are linear and sensitive to 0.1 mug: and there is little adsorption onto the liquid phase. The method has been successfully used for bile, and it has the potential for use on serum.

Gas-liquid chromatography of bile acids: a new liquid phase for both acetate and trimethylsilyl derivatives

Polymetaphenoxylene (PPE-20) has been found to be more useful than cyclohexane dimethanol succinate (HI-EFF-8-BP) for trimethylsilyl derivatives of bile acids and to be preferable to trifluoropropyl substituted silicone (OV-210, QF-1) for analysis of their acetate derivatives.

Bile acid pool in Wistar rats

The bile acid pool was found to be ca. 50 mumoles/100 g body wt in male and female rats maintained on standard laboratory chow and ca. 30 mumoles/100 g body wt in those maintained on a standard semisynthetic diet. The distribution of bile acids within the pool was similar in plasma, liver, and intestinal tract, except for a higher concentration of deoxycholic acid in the intestinal tract. Sex differences in bile acid composition were found to be influenced by the dietary regimen of the animals.

Semiquantitative measurement of lithocholic acid compounds in bile from patients with gallstones, before and during treatment with chenodeoxycholic acid

A method for two-dimensional thin-layer chromatography of unprocessed bile is described. The method gives distinct spots from lithocholic acid and its compounds with glycine, taurine, and sulfuric acid. The size of the spots is estimated by comparison with standard spots, and the concentrations of individual bile acids are expressed as a fraction of the total content of bile acids in the sample. The concentration of total lithocholic acid was found to be 1-3 (mean 1.5) per cent of the total concentration of bile acids in duodenal bile from 14 healthy persons. It was slightly higher in bile from 6 untreated patients with gallstones, and still higher, 3-7 (mean 4.0) per cent, in bile from the same patients during treatment with chenodeoxycholic acid. The difference between the concentrations of total lithocholic acid in the bile samples from healthy persons and from patients treated with chenodeoxycholic acid was statistically significant. Nearly all the lithocholic acid was conjugated with glycine or taurine, and approximately half of it was sulfated. The increase in total lithocholic acid concentration in the bile from patients consisted of glycine conjugates.

Toxicity of chenodeoxycholic acid in the rhesus monkey

Chenodeoxycholic acid is an important drug for the treatment of cholesterol cholelithiasis in man. Although no toxicity has been demostrated in man, liver lesions develop in rhesus monkeys treated with chenodeoxycholic acid. To elucidate the mechanism of toxicity, chenodeoxycholic acid. To elucidate the mechanism of toxicity, chenodeoxycholic acid was fed daily to three groups of 6 animals each at the following dose: 10, 40, and 100 mg per kg; 2 separate animals were not treated and served as controls. After 1 month, the animals were killed. During the treatment period, most blood tests (e.g., blood count, blood urea nitrogen, albumin, SGOT, lactate dehydrogenase) remained within normal limits, but there was a significant dose-related increase in serum leucine aminopeptidase levels. The percentage of lithochlic acid, the 7-dehydroxylated bacterial metabolite of chenodeoxycholic acid, rose from 1% in the control animal to almost 14% in the 100 mg per kg-treated group. Liver biopsies obtained before treatment and at necropsy showed no significant changes. Thus, exposure of the liver to increased amounts of lithocholic acid during chenodeoxycholic acid treatment might result in elevation of serum leucine aminopeptidase activity.

Toxicity of chenodeoxycholic acid in the nonhuman primate

Toxicologic aspects of long-term therapy with the gallstone-dissolving agent, chenodeoxycholic acid (CDC) are under study in the baboon. Eighteen animals, subdivided into low (20 mg. per kilogram per day), incremental (18 to 38 mg. per kilogram per day), and high (38 mg. per kilogram per day) dose groups were fed CDC daily for 8 to 15 months. During that period they maintained on appearance of excellent, unchanged health and behavior indistinguishable from that of eight control animals. However, 15 of the 18 CDC-fed animals showed significant elevations of monthly serum glutamic pyruvic transaminase-serum glutamic oxalacetic transaminase determinations, and 14 of the 18, from all dose groups, developed significant focal histologic changes in serial liver biopsies. Histologic changes are similar to those described for lithocholic acid toxicity and correlate with an elevated percentage of chenodeoxycholic acid and, particularly, with lithocholic acid (8 to 14 percent) in gallbladder bile of the CDC-fed animals. A few CDC-fed animals showed histologic changes without enzymatic changes and vice versa. To date none of the focal hepatic lesions appears irreversible; it is too early to determine whether continued CDC feeding results in progression, stabilization, or regression of changes. More intensive surveillance of human subjects receiving chenodeoxycholic acid is indicated.

Chenodeoxycholic acid therapy for gallstones: effectiveness, toxicity and influence on bile acid metabolism

Chenodeoxycholic acid (1 g daily) was administered to 10 patients with gallstones and three patients with biliary stricture and recurrent cholangitis. Four gallstone patients showed diminution or disappearance of stones including one patient whose stone was in the common bile duct. The patients with recurrent cholangitis showed marked improvement in symptoms during treatment. Serum bile acid levels were significantly elevated in 8 gallstone patients during treatment. Liver biopsy in eight gallstone patients during treatment revealed minor changes in five. Lithocholic acid and bile acid sulphates were found in only small amounts in the bile of patients during treatment. No significant trend in biliary lipid composition during treatment was observed. There was no overall trend in the group of patients whose stones disappeared or diminished. Changes in biliary bile acid composition and in bile acid pool sizes were variable following treatment and could not be correlated with the clinical results of treatment. A further trial of chenodeoxycholic acid is recommended in patients with stones in the biliary tree and recurrent cholangitis who are not amenable to surgical treatment.

Treatment of gallstones with chenodeoxycholic acid and phenobarbital

In a controlled trial, 36 patients with asymptomatic radiolucent gallstones were treated with chenodeoxycholic acid, 750 mg per day, phenobarbital, 180 mg per day, combination of both drugs, and placebo. After one year, chenodeoxycholic acid, phenobarbital and the combination, but not placebo, significantly decreased biliary cholesterol saturation. The effect was significantly greater with chenodeoxycholic acid and the combination than with phenobarbital. Gallstones size decreased more than 50 per cent in nine of 20 patients receiving chenodeoxycholic acid, either alone or combined with phenobarbital, but in no patient receiving only phenobarbital or placebo. Gallstones disappeared completely in tow patients. Abnormalities in liver-function tests in thriee of 36 patients and in five of 16 liver biopsies, occured with equal frequency in the four treatment groups. Thus, after one year, phenobarbital alone was ineffective in gallstone dissolution. Chenodeoxycholic acid alone or combined with phenobarbital, however, offered a partially effective and safe treatment for asymptomatic radiolucent gallstones.

Influence of primary bile acid feeding on cholesterol metabolism and hepatic function in the rhesus monkey

In three healthy rhesus monkeys fed chenodeoxycholic (chenic) acid, there was no consistent increase in the total exchangeable cholesterol pool or input to the cholesterol pool. In three similar monkeys fed cholic acid, the total exchangeable pool increased in all animals and input to the cholesterol pool increased in two. Serum glutamic-pyruvic transaminase (SGPT) increased transiently in two animals in each group. Morphologic abnormalities (triaditis with atypical ductular proliferation) were noted in one animal; this animal was ingesting chenic acid but had normal liver test results at the time of biopsy. Biliary bile acids contained 8 to 14 percent lithocholic acid in the chenic acid group and 48 to 72 percent deoxycholic acid in the cholic acid group.

Bile acid metabolism in cirrhosis. IV. Characterization of the abnormality in deoxycholic acid metabolism

Several recent studies have demonstrated that patients with cirrhosis frequently lack deoxycholic acid in bile and plasma. In order to explain this observation, comparative experiments on the colonic absorption of deoxycholic acid and on the colonic conversion of cholic to deoxycholic acid were carried out in the cirrhotic patients with normal and very low percentages of deoxycholic acid. Deoxycholic or cholic acid (100 mg) plus 5 muc of each [14C] bile acid were administered by enema to 8 patients with and 5 without liver disease. Deoxycholic acid produced a significant increase in the percentage of biliary deoxycholic acid in patients with cirrhosis. However, the rate of appearance of 14C-deoxycholic acid in patients with cirrhosis was slower than in normal control subjects. Distribution of the 14C activity among the bile acids indicated that rehydroxylation of deoxycholic to cholic acid did not occur. The distribution of 14C activity in biliary bile acids after the rectal administration of [14C]cholic acid showed that patients with severe cirrhosis converted [14C]cholic to [14C]deoxycholic acid at a much slower rate than did cirrhotic patients with normal percentages of biliary deoxycholic acid. Feeding of cholic acid (450 mg per day) for 3 days to 4 cirrhotic patients resulted in a 2-fold increase in the percentage of biliary cholic acid, but only a small increase in the percentage of deoxycholic acid. In a separate group of 9 cirrhotic patients, fecal bile acid analysis indicated that cirrhotic patients had a significantly lower percentage of deoxycholic acid than 12 patients without liver disease; there was no significant difference in fecal lithocholic acid. The data suggest that alteration of bacterial flora and/or altered conditions for bacterial 7alpha-dehydroxylase enzyme activity in the colon could account for the virtual absence of biliary deoxycholic acid in severely cirrhotic patients.

Occurrence of cholesterol crystals in human bile

The occurrence of cholesterol crystals was studied in 20 consecutive gallstone patients with functioning gallbladders. The frequency with which crystals were found rose sharply with the number of stones. Gallbladder bile was found more often to contain cholesterol crystals than hepatic bile of the same individual. Such crystals were absent in T tube drain bile from 10 consecutive choledochostomy patients, studied after the reestablishment of the enterohepatic circulation for at least five days. In gallstone patients in whom the gallbladder was visualized at cholecystography the hepatic bile contained cholesterol crystals more often than in patients with gallbladders not so visualized. In the latter patients the crystals tended to disappear after prolonged fasting. Bile analysis showed hepatic bile of patients with non-functioning gallbladders to be less lithogenic than bile in cases with functioning gallbladders. In the former group bile contained relatively more chenodeoxycholic acid than in the latter. The composition of bile with cholesterol crystals did not differ significantly from that of bile without crystals. In the final analysis it is important to identify possible factors responsible for the precipitation of cholesterol from supersaturated bile.

The role of bile acids in the pathogenesis of postvagotomy diarrhoea

The fecal excretion of bile acids was estimated in patients with postvagotomy diarrhoea, normal control subjects and a control group who had undergone truncal vagotomy and drainage but who did not have diarrhoea. The total daily bile acid excretion in the feces was significantly increased in the postvagotomy diarrhoea group: 2538 ± 632 mg (s.e.m.) compared with 799 ± 117 mg in the normal controls. There was no significant difference between the total daily bile acid excretion in the patients with postvagotomy diarrhoea and that of patients who had undergone vagotomy and drainage but who did not have diarrhoea. A significant increase in the fecal excretion of chenodeoxycholic acid was found in the postvagotomy diarrhoea group compared with the two control groups. This increase may be a factor in the pathogenesis of postvagotomy diarrhoea.