A simple method for the estimation of bile acids in serum

Pheromones of the male sea lamprey, Petromyzon marinus L.: structural studies on a new compound, 3-keto allocholic acid, and 3-keto petromyzonol sulfate

This study reports the results of chemical and chromatographic studies which establish the presence of 3-keto allocholic acid (3kACA) in water extracts from spermiating male sea lamprey, Petromyzon marinus. This is the second compound to be isolated and identified from these extracts. The first was 3-keto petromyzonol sulfate (3kPZS), which was shown to act as strong pheromonal attractant for ovulated females. Some new characterization data on 3kPZS (utilizing an only recently available synthetic preparation of the compound) is also included. The possibility that a mixture of 3kACA and 3kPZS might be a more potent pheromonal attractant than either compound alone is discussed.

Identification of the bile acid binding proteins in human serum by photoaffinity labeling

The binding of conjugated and unconjugated bile acids to human serum lipoproteins was investigated by density gradient centrifugation and photoaffinity labeling studies. The binding of bile acids to high-density lipoprotein increased by substitution of the 3 alpha-hydroxy group in cholate and taurocholate by a photolabile 3-azido or 3-azi-function. The affinity of bile acid derivatives to HDL showed the following ranking: 3 beta-azido-7 alpha,12 alpha-dihydroxy-,3,3-azo-7 alpha,12 alpha-dihydroxy- > 3 alpha,7 alpha,12 alpha-trihydroxy-,11 xi-azido-3 alpha,7 alpha,12 xi-trihydroxy- > 11 xi-azido-12-oxo-3 alpha,7 alpha-dihydroxy- > 7,7-azo-3 alpha,12 alpha-dihydroxy-,3 alpha,7 alpha-dihydroxy-,3 alpha,12 alpha-dihydroxy- > 3 alpha-hydroxy-cholan-24-oic acid. Based on the actual serum concentrations of albumin and HDL, a preference of hydrophilic bile acids to HDL is evident, the 3-azido- and 3-azi-derivatives showing a 5-23-fold higher binding to HDL compared to soluble serum proteins. For the identification of the bile acid binding proteins in human blood, photoaffinity labeling with a variety of photolabile conjugated and unconjugated bile acid derivatives was performed with subsequent analysis of radiolabeled serum proteins by one- and two-dimensional gel electrophoresis. In addition to albumin and the apolipoproteins A-I and A-II of high-density lipoproteins (Kramer et al. (1979) Eur. J. Biochem. 102, 1-9), three further proteins in the lipoprotein free serum fraction of M(r) 41,000, 50,000 and 83,000 were specifically labeled. By two-dimensional electrophoresis and by immunoprecipitation these proteins were identified as alpha 1-acid glycoprotein (M(r) 41,000), alpha 1-antitrypsin (M(r) 50,000) and transferrin (M(r) 83,000). No binding of bile acids to haptoglobin, alpha 2-HS-glycoprotein, hemopexin or alpha 1-fetoprotein occurred. In conclusion, these studies show that bile acid derivatives bind to several serum proteins in addition to albumin and furthermore that the substituent in position 3 of the steroid nucleus greatly influences the affinity of bile acids to high density lipoproteins.

Flow injection determination of glucose, bile acid and ATP using immobilized enzyme reactor and chemiluminescent assay of NAD(P)H

We have developed a chemiluminescent flow injection method for analysis of bile acid, glucose and ATP using the chemiluminescent assay of NADH using 1-methoxy-5-methylphenazinium methyl sulphate (1-MPMS)/isoluminol(IL)/microperoxidase (m-POD) system and immobilized enzyme reactors such as 3 alpha-hydroxysteroid dehydrogenase, glucose-dehydrogenase, hexokinase and glucose-6-phosphate dehydrogenase. The standard curves were obtained in the range of 5-100 pmol for bile acid, 0.5-5.0 nmol for glucose and 10(-7)-10(-5) mol/L for ATP. The coefficient of variation for each assay was not more than 4.1% for bile acid, 2.3% for glucose and 5.3% for ATP, respectively.

Total bile acids in hyperlipidaemic serum determined by bioluminescent and spectrophotometric methods

A simple, rapid and sensitive bioluminescent method has been used to measure total bile acids in hyperlipidaemic serum. We found that the levels of total bile acids in hypertriglyceridaemic and hypercholesterolemic sera determined by a spectrophotometric method were four-fold higher than those measured by the bioluminescent method (6.73 +/- 4.07 mumol/l (mean +/- SD) by bioluminescent and 26.10 +/- 13.42 mumol/l by the spectrophotometric method). There was no difference in total bile acid levels between these two methods for normal serum (4.72 +/- 3.38 mumol/l by bioluminescence and 4.49 +/- 3.27 mumol/l by the spectrophotometric method).

Serum bile acids in normal pregnancy

Serum bile acid levels were measured in a longitudinal study of 56 women throughout normal pregnancy. Postprandial levels of serum bile acids were measured at each visit. Mean serum bile acid levels increased significantly from 5.3 (2 SD 3.4) mumol/l at 16 weeks to 6.5 (2 SD 3.7) mumol/l at term (P less than 0.005).

Bile salt-induced intracellular Ca++ accumulation in type II pneumocytes

The pathogenesis of pneumonitis associated with meconium aspiration is poorly understood. To explore the possibility of pulmonary cytotoxicity in association with bile salt exposure and calcium accumulation, we compared cell viability, radiolabeled calcium accumulation, and intracellular [calcium] in the presence and absence of bile salts, chenodeoxycholate, and 3 beta-OH-5-cholenoate. We assessed viability of type II pneumocytes in culture by cell permeability to trypan blue dye, incorporation of leucine into cellular proteins, and cellular morphology. Intracellular calcium concentrations were monitored with fluorescent dye methodology. At micromolar concentrations, the above bile salts increased cell permeability by as much as 9-fold and decreased leucine incorporation by as much as 5-fold. Radiolabeled calcium accumulation increased by as much as 2.5-fold and intracellular [calcium] transiently increased by as much as 6-fold. Studies using bile salts extracted from meconium yielded similar results. Correlation of calcium accumulation to viability studies yielded a direct relationship with cell permeability and an inverse relationship with leucine incorporation. We speculate that bile salt-induced accumulation of intracellular calcium in lung cells may contribute to the pathogenesis of meconium aspiration pneumonitis.

Evaluation of gastrointestinal toxicity following cytostatic chemotherapy

A number of clinical and chemical parameters related to the gastrointestinal tract in patients treated with intensive chemotherapy for disseminated malignant melanoma were evaluated in order to find quantitative indicators for gastrointestinal toxicity and to investigate the cause of diarrhea after chemotherapy. In 11 patients 17 courses of polychemotherapy with bleomycin, DTIC, vindesine, and actinomycin D were administered, while the patients received complete liquid enteral nutrition. As clinical parameters for toxicity the diarrhea grading system according to the WHO criteria and the daily fecal consistency were used. Furthermore, in the feces Na+, K+, and Cl- (mmol/24 h), Na+/K+ ratio, dry and wet weight (g/24 h), lactate and bile acids (mmol/24 h), fat (g/24 h), pH, and osmolarity were determined. Both clinical parameters were closely correlated. The most important effects of the chemotherapy on the chemical parameters were an increased fecal fluid, K+, and fat excretion. The fecal wet weight and K+ excretion showed a high correlation with the two clinical parameters for gastrointestinal toxicity. We conclude that mucosal injury resulting from chemotherapy probably leads to increased small intestinal fluid and electrolyte secretion inducing diarrhea and that fecal wet weight and K+ excretion are probably the best quantitative indicators for gastrointestincal toxicity.

Fasting serum bile acid level in cirrhosis. A semi-quantitative index of hepatic function

We examined the roles of the factors which influence bile acid levels in order to define to what extent fasting serum total bile acid (FSTBA) level might reflect hepatic function and/or anatomy of the portal circulation in patients with cirrhosis. In a first group of 13 patients having mild to moderately advanced cirrhosis we determined the apparent oral clearance (CLo) of chenodeoxycholic acid (764 mumol) and their FSTBA levels. In a second group of 15 similar patients we measured FSTBA levels and by hepatic vein catheterization the intrinsic clearance (CLi) of ICG as well as total hepatic blood flow (Q). We found a significant inverse log-log relationship (r = 0.752, P less than 0.01) between the FSTBA and the CLo on the one hand and significant inverse log-log relationship (r = 0.707, P less than 0.01) between the FSTBA and CLi on the other hand. Q was not found to bear any significant relation to FSTBA (r = 0.120, P greater than 0.1). To conclude, in view of the observed relationship between CLi and CLo vs FSTBA, the latter might serve as a simple non-invasive semiquantitative index of hepatic function and/or anatomy of portal circulation in cirrhosis.

Colorimetric enzymatic measurement of serum total 3 alpha-hydroxy bile acid concentrations without extraction

A new method for the simpler colorimetric assay of serum total 3 alpha-hydroxy bile acid concentrations without prior extraction has been investigated. The lowest concentration that could be reliably measured was 3 mumol/l and the results obtained were in agreement with those obtained using extraction and the spectrofluorimetric enzymatic assay (y = 1.007x - 1.86, r = 0.99, n = 36). Results for 20 normal sera collected after an overnight fast were 6.2 +/- 5.1 mumol/l (mean +/- SD) and in 20 normal plasma randomly collected were 4.9 +/- 4.2 mumol/l. This new assay is comparable in specificity and sensitivity to the older spectrofluorimetric enzymatic assays and convenient for routine use.

A bioluminescence assay for total 3 alpha-hydroxy bile acids in serum using immobilized enzymes

A bioluminescence assay for bile acids was developed using a co-immobilized 3 alpha-hydroxysteroid dehydrogenase, diaphorase, and bacterial luciferase. The assay was specific for bile acids containing a free 3 alpha-hydroxyl group, as well as androsterone. Light output was linear over a bile acid concentration range of 1-20 000 pmol. Intra-assay precision was 6.2-8.2% and the recovery of added standards was 92-110%. Comparison of results using the bioluminescence assay with those using gas liquid chromatography revealed an excellent correlation (r = 0.99, n = 31). Since the bioluminescence assay is rapid, sensitive, specific, and uses inexpensive reagents, it appears to be an ideal method for the measurement of total bile acids in serum.

Continuous-flow automated assay of steroids with nylon-tube-immobilized hydroxysteroid dehydrogenases

Several NAD(P)+-dependent hydroxysteroid dehydrogenases, namely 3 alpha-hydroxysteroid dehydrogenase, beta-hydroxysteroid dehydrogenase, 7 alpha-hydroxysteroid dehydrogenase, and 12 alpha-hydroxysteroid dehydrogenase were separately immobilized on nylon tubes for the continuous-flow automated assay of hydroxysteroids. 3 alpha-Hydroxysteroid dehydrogenase was also immobilized on pore glass. Spectrophotometric monitoring in the visible region, where blank values were markedly reduced, was achieved through the Meldola blue catalyzed transfer of hydrogen from NAD(P)H to a tetrazolium salt. Nylon-tube-immobilized enzymes maintained 45-55% of the original activity after 1 month of intermittent use. The operational range, using the "end point" approach, was 1-25 nmol of steroid and the assay speed 10-15 samples/h. Reliable results were obtained in the determination of 3 alpha-hydroxysteroids and 3 beta, 17 beta-hydroxysteroids in urine and total bile acids in serum.

Estimation of ursodeoxycholic acid in human and bear biles using Clostridium absonum 7 beta-hydroxysteroid dehydrogenase

Ursodeoxycholic acid was estimated in bile samples from humans and wild North American black bears using 7 beta-hydroxysteroid dehydrogenase purified from Clostridium absonum by Procion Red affinity chromatography. The percentage ursodeoxycholic acid was calculated by two methods: (a) 7 beta-hydroxyl groups were quantified using 7 beta-hydroxysteroid dehydrogenase and 3 alpha-hydroxyl groups (total bile acids) were quantified using 3 alpha-hydroxysteroid dehydrogenase. The percentage ursodeoxycholic acid was calculated on the basis of [7 beta-hydroxyl groups]/[3 alpha-hydroxyl groups] X 100. (b) Bile was hydrolyzed with sodium hydroxide and subjected to thin-layer chromatography. Bands corresponding to cholic acid, chenodeoxycholic acid plus deoxycholic acid, and ursodeoxycholic acid were identified by the use of standards and Komarowsky's spray reagent. Total bile acids and total ursodeoxycholic acid were measured by elution of silica gel in unsprayed areas corresponding to the bile acid standards and quantification of the total bile acid in each eluate. Direct comparison of these methods validated the use of 7 beta-hydroxysteroid dehydrogenase in the estimation of ursodeoxycholic acid in the biles of black bears and of patients fed ursodeoxycholic acid for cholesterol gallstone dissolution. Relative percentages of ursodeoxycholic acid were 8-24% in four bears and 22 and 27% in the patients ingesting 500 and 750 mg ursodeoxycholic acid per day for 3 months, respectively. Predictably lower values were obtained in two control subjects and one patient ingesting 750 mg chenodeoxycholic acid per day for 3 months.

A bioluminescent assay for 12-alpha-hydroxy bile acids using immobilized enzymes

A bioluminescent assay for 12-alpha-hydroxy bile acids was developed using enzymes coimmobilized onto Sepharose 4B. The immobilized enzymes used were a bacterial 12-alpha-hydroxysteroid dehydrogenase, bacterial luciferase, and NADPH:FMN oxidoreductase or bacterial diaphorase. The assay was specific for 12-alpha-hydroxy bile acids and the lower limit of detection was 4 pmol/0.5 ml assay volume with a linear range of 4 to 2000 pmol. Intraassay precision was from 7.8 to 8.2%. Values obtained with this assay showed good agreement with those obtained by gas-liquid chromatography. The system using diaphorase was not stable at 4 degrees C in the absence of added thiol compounds, but could be stabilized by the addition of glutathione (0.5 mM). The assay is a convenient, a rapid, and an extremely sensitive method for the measurement of 12-alpha-hydroxy bile acid concentrations in the serum of patients or experimental animals.

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 +/- 0.7 mumol/liter rose to 3.0 +/- 0.8 mumol/liter postprandially. In patients mean fasting and stimulated CBA were only significantly raised in moderate to severe chronic and acute liver disease. Diagnostic sensitivity was poor in mild liver disease. Individuals with normal results were found in 8 of 11 disease categories. The ratio of stimulated to fasting CBA expressed in a stimulation quotient did not rise in more advanced liver disease. These findings are best explained by a constant fractional clearance of bile acids by the liver. We conclude that the serum conjugated bile acid determination as a test of liver cell function is not sensitive enough to identify all cases of biopsy-proven liver disease.

Determination of total bile acids in serum. A comparison of a radioimmunoassay with an enzymatic-fluorimetric method

A solid phase radioimmunoassay kit method for total conjugated bile acids has been compared to an enzymatic fluorimetric method for total serum bile acids. The methods were compared with respect to: precision, cross-reactivity (molar equivalence) of different bile salts, recovery of different bile salts from serum, the reference range for a healthy population, linearity, coefficient of correlation, diagnostic effectiveness, cost and ease of assay. Both assays seemed equally capable of predicting the presence or absence of liver disease. Radioimmunoassay had little advantage over the enzymatic-fluorimetric method. Its relative ease was far outweighed by its greater cost and poorer analytical performance.

Evaluation of a commercial enzymatic method for the determination of total serum bile acids

An enzymatic method (Sterognost-3 alpha Flu, Nyegaard & Co, Oslo, Norway) for the determination of total serum bile acids has been evaluated, and reference values for fasting and postprandial total serum bile acids have been established. Precision was rather low in the lower normal range but satisfactory in the upper reference range and for elevated values. The upper reference value for fasting total serum bile acids was 5.0 mu mol/l. Maximal postprandial elevations occurred at varying intervals after a test meal and the upper postprandial reference value was 12 mu mol/l. Certain serum samples were also analysed by radioimmunological methods for conjugates of cholic and chenodeoxycholic acids. The values obtained with the enzymatic method correlated satisfactorily with those of the radioimmunoassay methods for most of the serum samples analysed. However, a number of samples with slightly elevated bile acid concentrations, as measured by the comparison radioimmunoassay methods, were found to have normal total serum bile acids when measured by the enzymatic method.

Reversed-phase high-performance liquid chromatographic separation and quantification of individual human bile acids

The reversed-phase high-performance liquid chromatographic separation and quantification of individual bile acids is described. Taurine- and glycine-conjugated bile acids were separated and detected directly by an ultraviolet absorbance detector operating at 200 nm. Simultaneous quantitation of at least 100 ng of each conjugated bile acid is possible. Carboxylic (free and glycine-conjugated) bile acids were esterified with p-bromophenacyl-bromide. The reaction, using N,N-diisopropylethylamine as catalyst, yields quantitatively the strongly absorbing p-bromophenacyl esters whch can be determined by absorbance measurement at 254 nm. Simultaneous quantitation of less than 20 ng of each bile acid is possible. The present method is applied to the quantitation of individual bile acids in ten human gallbladder bile samples.

A direct fluoroimmunoassay for conjugated chenodeoxycholic acid using antibody coupling to magnetisable particles

A novel solid phase fluoroimmunoassay for conjugated chenodeoxycholic acid has been developed employing an antiserum coupled to magnetisable cellulose particles and a chenodeoxycholyl glycinefluorescein thiocarbamyl ethylene diamine conjugate as the label. The data obtained from serum samples from 25 patients correlated closely (r = 0.99) with those obtained by radioimmunoassay. The assay is rapid (30 minutes), simple, and ideal for routine clinical purposes.

Gallstone dissolution with chenodeoxycholic acid. A clinical study

Out of 95 patients with radiolucent gallstones who enrolled in a clinical study with chenodeoxycholic acid (CDC) for gallstone dissolution 75 patients with cholecystolithiasis completed 12 months of treatment. As a side effect 31% of patients reported intermittent diarrhea which did not cause cessation of therapy or missing of work. The incidence of biliary colic was markedly decreased during treatment in comparison to the rate in the year before. From more than 20 laboratory values checked before start and every 3 months during therapy only aminotransferases increased up to 3 fold in 20% of patients. gamma-GT elevated in 31% of patients before treatment improved in half of these patients during therapy. Gallstone dissolution defined as 30% or more diminution of the gallstone area on comparable x-rays occurred in 40% of patients. Analysis of factors showed that gallstones above 2 cm in diameter did not dissolve. When the dose of CDC was retrospectively related to body weight a success rate of 68% was found in the group taking more than 13 mg CDC/kg/day. The lithogenic index determined at 6 and 12 months had significantly decreased after 6 months in patients with success. This study demonstrates that medical dissolution of gallstones with chenodeoxycholic acid should be performed in patients with radiolucent stones of less than 2 cm in diameter and with a dose above 13 mg CDC/kg body weight/day. Under these conditions the success rate is above 60% accompanied by minimal side effects.

The concentration of serum bile acids during the course of acute hepatitis B

The concentration of total 3-alpha-hydroxy bile acids in serum, conventional liver function tests, and hepatitis B surface antigen were assessed during the course of acute hepatitis B in 37 patients. The initially highly elevated serum bile acids decreased to reference levels more rapidly than the conventional liver function tests. Moreover, it was shown that prolonged elevations of serum bile acids may predict progression of the disease to chronicity.

Tupaias (tree shrews)--a new animal model for gallstone research. II. Influence of fat, sugar, and cholesterol on bile composition

The lipid composition of bile obtained from the gallbladder and from the liver of tupaias was determined. Compared to the gallbladder bile of man, the gallbladder bile of tupaias contains the same percentage of phospholipids (PL), one third of the cholesterol (CH), and 50% more total bile acids (TBA). The lithogenic index (LI) of the bile is about 0.2--0.3. No significant sex differences or diurnal variations are found in the composition of bile. The concentration of PL, CH, and TBA is found 5 to 8 times higher in the gallbladder bile than in the liver bile. The bile acid spectrum in tupaias equals that in man qualitatively and is similar quantitatively. In a feeding experiment, the influences of butter, cholesterol, butter plus cholesterol and sucrose on bile composition, clinicochemical serum values, and liver and gallbladder histology were studied. Groups of six animals each were fed the different diets over a 10-week period. In group A: 20% butter added to the standard diet, PL content was higher, the LI was unchanged. In group B: 2% cholesterol added to the standard diet, the CH value and the LI were elevated, CH crystals but no stones were found. In group C: 2% cholesterol and 20% butter in the standard diet, stone formation was observed. PL and CH values were higher than in group A and B, TBA values were lower. In group D: 50% sucrose added to the standard diet very low PL and TBA values were determined in the liver bile, resulting in elevated LIs. It is concluded that all three components of a diet, which had proven lithogenic in a preceding experiment (Schwaier, 1979a), contribute to gallstone formation.

Bile acid studies in patients with Crohn's colitis

Bile acid studies were performed in patients with Crohn's disease, radiologically confined to the colon. The bile acid pool size of 10 patients with isolated Crohn's colitis was significantly lower than that of 10 normal control subjects (P less than 0.001) and of 10 ulcerative colitis patients (P less than 0.005). Measurements of 14C-excretion in breath and in 24 hours stool collections after the administration of 5 muCi 14C-glycocholate showed a normal 14C-excretion in breath and usually a markedly increased loss of 14C in the stool (greater than 7% of the dose). The simultaneous administration of 5 muCi 3H-polyethylene glycol MW 4000 (3H-PEG) as a marker indicated that the 14C/3H ratio in the patients with Crohn's colitis was significantly greater than in a control series of patients with diarrhoea not due to bile acid malabsorption. Studies on the composition of duodenal bile showed a significantly decreased concentration of deoxycholic acid in duodenal bile. These observations suggest bile acid malabsorption in patients with Crohn's disease apparently confined to the colon.

Bile salt binding to serum components. Taurocholate incorporation into high-density lipoprotein revealed by photoaffinity labelling

1. Photoaffinity labelling of human serum albumin with the sodium salts of (3 beta-azido-7 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oyl)-2-amino[2(-3)H (N)]ethanesulfonic acid, (7,7-azo-3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oyl)-2-amino[2(-3)H (N)]ethanesulfonic acid and (11 zeta-azido-12-oxo-3 alpha,7 alpha-dihydroxy-5 beta-cholan-24-oyl)-2-amino[2(-3)H (N)]ethanesulfonic acid resulted, in each case, in a considerable covalent incorporation of radioactivity into the protein. 2. Photoaffinity labelling of whole serum, obtained from fasting test persons, revealed with all three photolabile derivatives of taurocholate at the physiological concentration of 2.1 microM the incorporation of radioactivity not only into albumin but also into high-density lipoprotein, as demonstrated by density gradient centrifugation and by immunological characterization. 3. The bulk of radioactivity incorporated into high-density lipoprotein by photoaffinity labelling of whole serum was found to have been associated with the lipids. Only 10-20% of the label was covalently bound to apolipoproteins, predominantly to the apolipoproteins A-I and A-II. 4. The interaction of taurocholate with high-density lipoprotein has been confirmed by density gradient centrifugation using 14C-labelled taurcholate. It is assumed that the interaction of taurocholate with high-density lipoprotein is physiologically of significance.

Bile acid sulfates in serum bile acids determination

Some bile acid sulfates were synthesized and characterized. The configuration of sulfate groups at C-3, C-7 and C-12 positions was confirmed by Nuclear Magnetic Resonance analysis. These sulfates were utilized in a study of their chemical behaviour in different analytical procedures currently used for serum bile acids determination. Procedures for bile acids extraction from serum with ethanol or Amberlite XAD-2 result in an important loss of the most polar sulfated bile acids. Complete separation of unsulfated from sulfated bile acids on Sephadex LH-20 is not achieved when deconjugation of the most polar bile acid sulfate is slow but does not produce artifacts. Enzymatic determination of bile acids gives positive response with some bile acid sulfates. The current procedures of serum bile acids determination are discussed in consideration of these results.

Determination of total 3 alpha-hydroxy bile acids in serum

The usual techniques for determination to total 3 alpha-hydroxy bile acids in serum involving liquid-solid extraction of the bile acids with the adsorbent XAD-2 and fluorimetric measurement of NADH generated from the reaction with a NAD-linked 3 alpha-hydroxysteroid dehydrogenase are evaluated and improved. The influence of different types of enzyme preparations on the results is examined. The results with the improved technique are compared to the results obtained with another method, avoiding extraction of the bile acids before the enzymatic reaction which is followed by fluorimetric measurement of resorufin, produced by transfer of the hydrogen of the generated NADH by diaphorase to resazurin. No significant difference between the results with the two types of methods was found. The concentration of total 3 alpha-hydroxy bile acids in serum of 46 fasting 'healthy' individuals aged 17 to 82 years is estimated. 30 were females, of whom 10 were taking estrogen-containing oral contraceptives, and 16 were males. Mean +/- standard deviation in all the females was 3.0 +/- 1.1 micromol/l, and in the males 4.0 +/- 1.9 micromol/l. There was no significant difference between any of the groups.

A highly specific 125I-radioimmunoassay for cholic acid conjugates

Several modifications of the immunization procedure permitted development of a highly specific radioimmunoassay (RIA) for cholic acid conjugates. Antiserum was produced in guinea pigs using cholic acid-thyroglobulin complex as immunogen. 125-I-Cholyglycylhistamine was prepared as radioactive ligand according to a modification of the method of Spenney et al. (Spenney, J.G., Johnson, B.J., Hirschowitz, B.I., Mihas, A.A. and Gibson, R. (1977) Gastroenterology 72, 305--311). The association constant of the antisera to taurocholic acid was 1.8 x 10(7) l/mol, the working range of the assay between 9.5--890 pmol. Cross-reactivities of the antiserum to bile acids other than cholic acid species were less than 3%, which is lower than for any published bile acid RIA. Concentrations of cholic acid conjugates in sera obtained from 17 healthy fasting volunteers ranged from 0.4--1.9/mumul/l.

Determination of bile acids in serum by capillary gas-liquid chromatography

A glass capillary column and an appropriate relatively simple procedure for sample preparation have been developed for determination of serum bile acids. Sample preparation involved extraction with Amberlite XAD-2, solvolysis of sulfates, enzymatic hydrolysis with cholylglycine hydrolase, methylation and silylation. Because of complete chromatographic separation of bile acid trimethylsilylether derivatives from cholesterol on the capillary column, an additional step for elimination of cholesterol could be omitted. Trimethylsilylether derivatives were separated on a 20 meter x 0.3 mm i.d. glass capillary column covered with a crystal layer of barium carbonate and coated with polyethyleneglycol 20,000 as liquid phase according to Grob, K. and Grob, G. (1976) J. Chromatogr.125, 471--485, and Grob, K., Grob, G. and Grob, Jr., K., (1977) Chromatographia 10, 181--187. Overall recovery of the major human conjugated bile acids ranged from 86 to 89%. Reproducibility of bile acid determination was satisfactory in both normal and pathological serum with elevated bile acid concentrations (coefficient of variation 7.6 to 10.0%). The mean concentrations of cholic, deoxycholic, chenodeoxycholic and lithocholic acid in the serum of healthy subjects were 0.9, 1.0, 1.7 and 0.2 mumol/l in males, and 1.0, 0.8, 1.4 and 0.2 mumol/l in females.

Assessment of cerulein effects on serum bile acids concentration in liver disease. Comparison with the test meal

Twenty-four liver patients and seven healthy subjects underwent the enzymatic-fluorimetric assay of total serum bile acids during fasting and after a hyperlipidic meal, both alone and with the intramuscular administration of 0.3 microgram/kg of cerulein. A third test with cerulein alone was carried out on the control group and on 12 liver patients. The liver patients were divided into two groups; those with moderate and severe liver disease, according to the degree of liver function impairment and the clinical data. The best discriminant efficiency was observed in the test with the meal alone, even if, in the liver patients, the meal with cerulein caused a greater percentual increase of serum bile acids. After taking into account the most significant correlations between serum bile acids and liver function tests, the addition of cerulein to the meal may be recommended for liver patients with previous cholecystectomy or gallbladder pathology.

A bile-acid-rich high-density lipoprotein (HDL) in acute hepatitis

Severe liver dysfunction is often associated with alterations of plasma lipids and lipoproteins. In this study the high-density lipoprotein (HDL) class has been further investigated. HDL from patients with acute, cholestatic hepatitis (n = 10) was isolated and compared with that of normals. Lipid and protein analyses were performed during the acute stage of the disease, with consequent follow-up studies. It was found that (1) only apo A-I was decreased by 50% in the isolated HDL fractions, whereas apo A-II remained unchanged; apo A-I in total plasma was normal; (2) immunoelectrophoresis of hepatitis HDL against monospecific anti-A-II revealed one precipitin line but two or more bands against anti-A-I; (3) concomitant with an increase of phospholipids and a decrease of triglycerides and the total cholesterol fraction, hepatitis HDL contained 10--12 times more bile acid than normal HDL. Chenodeoxycholic acid was the predominant bile acid. These alterations were fully reversible when patients recovered. These parameters seem to be sensitive markers for the degree of disturbance and restoration of liver function. The structural-functional implications of the observed compositional changes of HDL during cholestasis are discussed.

Serum total lipids, lipoprotein cholesterol, and apolipoprotein A in acute viral hepatitis and chronic liver disease

Serum total lipids, lipoprotein cholesterol, apolipoprotein A (Apo A), and liver function tests have been investigated in patients with acute viral hepatitis and chronic liver disease. Hypertriglyceridaemia, absence of alpha and pre beta bands on the lipoprotein electrophoresis pattern, low level of Apo A, and presence of abnormal lipoproteins (beta-VLDL and beta2-LP) were observed in the early phase of acute hepatitis. A positive correlation was found between Apo A and high-density lipoprotein cholesterol, and a negative one between Apo A and triglyceride, bile acids, total bilirubin, and serum alanine aminotransferase. Lipoprotein abnormalities found in the early phase of acute hepatitis are probably due to low lecithin-cholesterol acyltransferase activity. The reappearance of alpha lipoprotein and the increase of Apo A are sensitive indices of improvement of liver function. In chronic liver disease low levels of cholesterol and Apo A indicate the severity of liver cell injury.

Polymorphic acetylation and aminopyrine demethylation in Gilbert's syndrome

Polymorphic acetylation was investigated in twenty-seven patients with Gilbert's syndrome using the sulphadimidine test. Whereas the finding of 51% slow acetylators in seventy-eight control persons agreed well with the expected frequency in a continental European population, the prevalence of slow acetylators in Gilbert's syndrome was increased to 78% (P less than 0.03, Woolf's G-test). After oral administration of 14C-aminopyrine there was no significant difference between seventeen patients with Gilbert's syndrome and twenty-seven normal controls in total plasma clearance of aminopyrine (280 +/- SD 100 and 270 +/- 60 ml/min) and in the disappearance curve of 14CO2 in breath (0.23 +/- 0.04 and 0.22 +/- 0.03 h-1, respectively). Thus, whereas aminopyrine metabolism appears unaffected in the examined patients, the data documents a new association between slow acetylator status and Gilbert's syndrome.