Individual Serum Bile Acids Research Articles

Astragalus saponins protect against extrahepatic and intrahepatic cholestatic liver fibrosis models by activation of farnesoid X receptor

Ethnopharmacological relevanceCholestatic Liver Fibrosis (CLF) is a hepatobiliary disease that typically arises as a late-stage complication of cholestasis, which can have multiple underlying causes. There are no satisfactory chemical or biological drugs for CLF. Total Astragalus saponins (TAS) are considered to be the main active constituents of the traditional Chinese herb Astragali Radix (AR), which has the obvious improvement effects for treating CLF. However, the mechanism of anti-CLF effects of TAS is still unclear. Aim of the studyThe present study was undertaken to investigate the therapeutic effects of TAS against bile duct ligation (BDL) and 3, 5-diethoxycarbonyl-1,4-dihydroxychollidine (DDC) -induced CLF models and to reveal the potential mechanism to support its clinic use with scientific evidence. Materials and methodsIn this study, BDL-induced CLF rats were treated with TAS (20 mg/kg, 40 mg/kg) and DDC-induced CLF mice were treated with 56 mg/kg TAS. The therapeutic effects of TAS on extrahepatic and intrahepatic CLF models were evaluated by serum biochemical analysis, liver histopathology and hydroxyproline (Hyp). Thirty-nine individual bile acids (BAs) in serum and liver were quantified by using UHPLC-Q-Exactive Orbitrap HRMS. qRT-PCR, Western blot and immunohistochemistry analysis were used to measure the expression of liver fibrosis and ductular reaction markers, inflammatory factors and BAs related metabolic transporters, along with nuclear receptor farnesoid X receptor (FXR). ResultsThe serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TBiL), direct bilirubin (DBiL) and contents of liver Hyp were dose-dependently improved after treatment for TAS in BDL and DDC- induced CLF models. And the increased levels of ALT and AST were significantly improved by total extract from Astragali radix (ASE) in BDL model. The liver fibrosis and ductular reaction markers, α-smooth muscle actin (α-SMA) and cytokeratin 19 (CK19), were significantly ameliorated in TAS group. And the liver expression of inflammatory factors: interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) were significantly decreased after TAS treatment. In addition, TAS significantly ameliorated taurine-conjugated BAs (tau-BAs) levels, particularly α-TMCA, β-TMCA and TCA contents in serum and liver, which correlated with induced expressions of hepatic FXR and BAs secretion transporters. Furthermore, TAS significantly improved short heterodimer partner (SHP), cholesterol 7α-hydroxylase (Cyp7a1), Na+ taurocholate cotransport peptide (NTCP) and bile-salt export pump (BSEP) mRNA and protein expression. ConclusionsTAS exerted a hepatoprotective effect against CLF by ameliorating liver injury, inflammation and restoring the altered tau-BAs metabolism to produce a positive regulatory effect on FXR-related receptors and transporters.

Recognition of specific types of drug-induced liver injury using random forest algorithm: the importance of individual serum bile acid level

Recognition of specific types of drug-induced liver injury using random forest algorithm: the importance of individual serum bile acid level

Case-control exercise challenge study on the pathogenesis of high serum gamma-glutamyl transferase activity in racehorses.

High serum γ-glutamyl-transferase (GGT) activity syndrome in racehorses has been associated with maladaption to exercise. Investigation of affected horses before and immediately after standard exercise may provide critical insight into the syndrome's pathophysiology. To investigate blood biomarker changes in actively competing racehorses with high GGT activity associated with an exercise challenge. Case-control study. High GGT case (age: 2-3 years) and normal GGT control (age: 2-7 years) pairs (3 Thoroughbred, 4 Standardbred pairs) at least 3months into their training/racing season were included. Horses with a recent history of high GGT activity (≥50 IU/L) without additional biochemical evidence of liver disease were identified by veterinarians. Horses were tested again in the week prior to a planned exercise challenge to confirm persistent increases in GGT activity. Controls from the same stable with similar training/racing intensity and serum GGT activity ≤36 IU/L were matched with each case. Blood samples were obtained immediately before, 15 and 120 min after exercise. Pre-exercise serum samples were analysed for baseline select serum chemistries, selenium and vitamin E concentrations. Cortisol concentration and markers of oxidative status were measured in serum or plasma for all time points. Individual serum bile acid and coenzyme Q10 concentrations, plasma lipid mediator (fatty acids, oxylipids, isoprostanes) concentrations and targeted metabolomics analyses were performed using liquid chromatography-mass spectrometry. Serum viral PCR for equine hepaci- and parvovirus was performed in each animal. Cases had higher baseline concentrations of total glutathione, taurocholic acid, cortisol and cholesterol concentrations and higher or lower concentrations of specific oxylipid and isoprostane mediators, but there were no case-dependent changes after exercise. Small sample size. Results indicated that glutathione metabolism was altered in high GGT horses. Enhanced glutathione recycling and mild cholestasis are possible explanations for the observed differences.

Use of bile acids as potential markers of liver dysfunction in humans: A systematic review.

Objective:This study aimed to determine the effectiveness of using total, individual serum, or urinary bile acids (BA) as potential markers of liver dysfunction.Methods:We searched the PubMed and Web of Science databases using the following keywords- “serum bile acids,” “liver dysfunction,” “liver injury,” “liver disease,” “traditional liver function tests,” “Chronic liver disease,” “acute liver injury”. The search was complemented by manual screening of the list of references for relevant articles. We selected only English-language manuscripts for adult patients based on predetermined inclusion and exclusion criteria. Animal studies and studies on neonates and children were not included.Outcome measures:Changes in BA concentrations or ratios at or prior to changes in liver function tests.Results:A total of 547 studies were identified, of which 28 were included after reading the entire manuscript. These studies included 1630 patients and 836 controls published between 1990 and 2017. The methods used in BA assays varied significantly, and the studies did not agree. on specific individual BA or BA ratios as biomarkers of specific liver injury or dysfunction. Except for the prognostic value of BA in intrahepatic cholestasis of pregnancy (ICP), studies have failed to provide evidence for BA as a liver biomarker.Conclusions:Despite the research conducted on BA for over 27 years, there are inconsistencies in the reported results and a lack of solid evidence to support the use of individual BA or BA ratios as biomarkers of liver injury. Adequately conducted studies needed to resolve this limitation in the literature.

Da-Huang-Xiao-Shi decoction protects against3, 5-diethoxycarbonyl-1,4-dihydroxychollidine-induced chronic cholestasis by upregulating bile acid metabolic enzymes and efflux transporters

Ethnopharmacological relevanceChronic cholestasis is a usual clinical pathological process in hepatopathy and has few treatment options; it is classified under the category of jaundice in Chinese medicine. Da-Huang-Xiao-Shi decoction (DHXSD) is a classic Chinese prescription which is used to treat jaundice.Aim of the study: We aimed to examine the protective effect of DHXSD on liver and its potential mechanism of action against chronic cholestasis. Materials and methodsChronic cholestasis was induced using 3, 5-diethoxycarbonyl-1,4-dihydroxychollidine (DDC) in mice. Mice were then administered DHXSD intragastrically at doses of 3.68, 7.35, and 14.70 g/kg for four weeks followed by further analyses. Serum biochemical indices and liver pathology were explored. Eighteen individual bile acids (BAs) in mice serum and liver were quantified using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The expression of BA related metabolic enzymes, transporters, along with nuclear receptor farnesoid X receptor (FXR) was detected by real-time qPCR and Western blot. ResultsDHXSD treatment reduced the serum biochemical indices, ameliorated pathological injury, and improved the disordered BA homeostasis. Mice treated with DHXSD showed significantly upregulated expression of the metabolic enzymes, cytochrome P450 2b10 (Cyp2b10), Cyp3a11, and UDP-glucuronosyltransferase 1a1 (Ugt1a1); and the bile acid transporters, multidrug resistance protein 2 (Mdr2), bile salt export pump (Bsep), and multidrug resistance-associated protein 3 (Mrp3). DHXSD treatment also significantly upregulated FXR expression in mice with DDC-induced chronic cholestasis. ConclusionsDHXSD exerted protective effects on chronic cholestasis in DDC-treated mice by alleviating the disordered homeostasis of BAs through increased expression of BA related metabolic enzymes and efflux transporters.

Individual serum bile acid profiling in rats aids in human risk assessment of drug-induced liver injury due to BSEP inhibition

Drug-induced liver injury (DILI) has been the most frequent cause of post-marketing drug withdrawals in the last 50years. The multifactorial nature of events that precede severe liver injury in human patients is difficult to model in rodents due to a variety of confounding or contributing factors that include disease state, concurrent medications, and translational species differences. In retrospective analyses, a consistent risk factor for DILI has been the inhibition of the Bile Salt Export Pump (BSEP). One compound known for potent BSEP inhibition and severe DILI is troglitazone. The purpose of the current study is to determine if serum profiling of 19 individual bile acids by liquid chromatography-mass spectrometry (LC/MS) can detect perturbations in bile acid homeostasis in rats after acute intravenous (IV) administration of vehicle or 5, 25, or 50mg/kg troglitazone. Minimal serum transaminase elevations (approximately two-fold) were observed with no evidence of microscopic liver injury. However, marked changes in individual serum bile acids occurred, with dose-dependent increases in the majority of the bile acids profiled. When compared to predose baseline values, tauromuricholic acid and taurocholic acid had the most robust increase in serum levels and dynamic range, with a maximum fold increase from baseline of 34-fold and 29-fold, respectively. Peak bile acid increases occurred within 2hours (h) after dosing and returned to baseline values before 24h. In conclusion, serum bile acid profiling can potentially identify a mechanistic risk of clinical DILI that could be poorly detected by traditional toxicity endpoints.

Cholestatic drugs induce preferential accumulation of toxic bile acids in human HepaRG cells

Drug-induced liver injury (DILI) has been the most frequent cause of post-marketing drug withdrawals in the last 50 years. The multifactorial nature of events that precede severe liver injury in human patients is difficult to model in rodents due to a variety of confounding or contributing factors that include disease state, concurrent medications, and translational species differences. In retrospective analyses, a consistent risk factor for DILI has been the inhibition of the Bile Salt Export Pump (BSEP). One compound known for potent BSEP inhibition and severe DILI is troglitazone. The purpose of the current study is to determine if serum profiling of 19 individual bile acids by liquid chromatography-mass spectrometry (LC/MS) can detect perturbations in bile acid homeostasis in rats after acute intravenous (IV) administration of vehicle or 5, 25, or 50 mg/kg troglitazone. Minimal serum transaminase elevations (approximately two-fold) were observed with no evidence of microscopic liver injury. However, marked changes in individual serum bile acids occurred, with dose-dependent increases in the majority of the bile acids profiled. When compared to predose baseline values, tauromuricholic acid and taurocholic acid had the most robust increase in serum levels and dynamic range, with a maximum fold increase from baseline of 34-fold and 29-fold, respectively. Peak bile acid increases occurred within 2 hours (h) after dosing and returned to baseline values before 24 h. In conclusion, serum bile acid profiling can potentially identify a mechanistic risk of clinical DILI that could be poorly detected by traditional toxicity endpoints.

Circulating bile acids predict outcome in critically ill patients

BackgroundJaundice and cholestatic hepatic dysfunction are frequent findings in critically ill patients associated with increased mortality. Cholestasis in critically ill patients is closely associated with stimulation of pro-inflammatory cytokines resulting in impaired bile secretion and subsequent accumulation of bile acids.Aim of this study was to evaluate the clinical role of circulating bile acids in critically ill patients.MethodsTotal and individual serum bile acids were assessed via high-performance liquid chromatography in 320 critically ill patients and 19 controls.ResultsTotal serum bile acids were threefold higher in septic than cardiogenic shock patients and sixfold higher than in post-surgical patients or controls (p < 0.001). Elevated bile acid levels correlated with severity of illness, renal dysfunction and inflammation (p < 0.05). Total bile acids predicted 28-day mortality independently of sex, age, serum bilirubin and severity of illness (HR 1.041, 95% CI 1.013–1.071, p < 0.005). Best prediction of mortality of total bile acids was seen in patients suffering from septic shock.ConclusionsIndividual and total BAs are elevated by various degrees in different shock conditions. BAs represent an early predictor of short-term survival in a mixed cohort of ICU patients and may serve as marker for early risk stratification in critically ill patients. Future studies should elucidate whether modulation of BA metabolism and signalling influences the clinical course and outcome in critically ill patients.

Serum bile acids in patients with hepatopulmonary syndrome.

Background Hepatopulmonary syndrome (HPS) occurs in 20 - 30 % of patients with cirrhosis and is associated with increased mortality. Cholestasis and accumulation of bile acids (BAs) play a major role in chronic liver disease. Aim We aimed to evaluate the clinical role of serum BAs in patients with HPS. Methods Seventy-four patients with cirrhosis were included in this prospective study. Marker for cholestasis as total and individual serum BAs, bilirubin, alkaline phosphatase (AP), and gamma-glutamyl transpeptidase (GGT) were analyzed in patients screened for HPS. Criteria of HPS were fulfilled in 26 patients (35 %). Results In contrast to AP and GGT, bilirubin and serum BAs were significantly elevated in patients with HPS (median total BAs in HPS 83.5 μmol/L, IQR 43.1 - 148.9 vs. no HPS 26.9 μmol/L, 11 - 75.6; p < 0.001). Total BAs correlated with gas exchange by means of PaO2 / AaPO2 (r: -0.28, p < 0.05; r: 0.24, p < 0.05) and portal pressure (r: 0.33, p < 0.05). BAs were associated with HPS independently severity of underlying liver disease (OR: 1.012, 95 % CI:1.001 - 1.023, p < 0.05). Conclusion BA retention is associated with HPS and gas exchange abnormalities. Future studies should assess whether modulation of BAs signaling may impact the course of HPS.

Target profiling analyses of bile acids in the evaluation of hepatoprotective effect of gentiopicroside on ANIT-induced cholestatic liver injury in mice

Ethnopharmacological relevanceGentiopicroside (GPS), one of iridoid glucoside representatives, is the most potential active component in Gentiana rigescens Franch. ex Hemsl and Gentiana macrophylla Pall. These two herbs have been used to treat jaundice and other hepatic and billiary diseases in traditional Chinese medicine for thousands of years. Aim of the studyThis study aimed to investigate the protective effects and mechanisms of GPS on α-naphthylisothiocyanate (ANIT) induced cholestatic liver injury in mice. Materials and methodsMice were treated with GPS (130mg/kg, ig) for 5 consecutive days. On the third day, mice were given a single dose of Alpha-naphthylisothiocyanate (75mg/kg, ig). Serum biochemical markers and individual bile acids in serum, liver, urine and feces were measured at different time points after ANIT administration. The expression of hepatic bile acid synthesis, uptake and transporter genes as well as ileum bile acid transporter genes were assayed. ResultsIn this study, ANIT exposure resulted in serious cholestasis with liver injury, which was demonstrated by dramatically increased serum levels of ALT, ALP, TBA and TBIL along with TCA CA, MCAs and TMCAs accumulation in both liver and serum. Furthermore, ANIT significantly decreased bile acid synthesis related gene expressions, and increased expression of bile acid transporters in liver. Continuous treatment with GPS attenuated ANIT-induced acute cholestasis as well as liver injury and correct the dyshomeostasis of bile acids induced by ANIT. Our data showed that GPS significantly upregulated the hepatic mRNA levels of synthesis enzymes (Cyp8b1 and Cyp27a1) and transporters (Mrp4 Mdr1 and Ost-β) as well as ileal bile acid circulation mediators (Asbt and Fgf15), accompanied by serum and hepatic bile acid levels decrease and further urinary and fecal bile acid levels increase. ConclusionGPS can change bile acids metabolism which highlights its importance in mitigating cholestasis, resulting in the marked decrease of intracellular bile acid pool back toward basal levels. And the protective mechanism was associated with regulation of bile acids-related transporters, but the potential mechanism warrants further investigation.

Serum bile acids as marker for acute decompensation and acute-on-chronic liver failure in patients with non-cholestatic cirrhosis.

Retention of bile acids (BAs) plays a central role in hepatic damage and disturbed BA signalling in liver disease. However, there is lack of data regarding the association of BAs with clinical complications, acute decompensation (AD) and acute-on-chronic liver failure (ACLF). Thus, we aimed to evaluate the impact of circulating serum BAs for complications in patients with cirrhosis. One hundred and forty-three patients with cirrhosis were included in this prospective cohort-type observational study. Total serum BAs and individual BA composition were assessed in all patients on admission via high-performance liquid chromatography. Clinical complications with respect to AD, ACLF and 1-year transplant-free survival were recorded. Total BAs and individual serum BAs were significantly higher in patients with bacterial infection, AD and ACLF (P<.001) and correlated significantly with model of end-stage liver disease (MELD) and hepatic venous pressure gradient (P<.001). Total BAs predicted new onset of AD or ACLF during follow-up (OR 1.025, 95% CI: 1.012-1.038, P<.001). Best cut-off predicting new onset of AD/ACLF and survival during course of time was total BAs ≥36.9μmol/L. Serum total and individual BAs are associated with AD and ACLF in patients with cirrhosis. Assessment of total BAs could serve as additional marker for risk stratification in cirrhotic patients with respect to new onset of AD and ACLF.

Long-Term Ursodeoxycholic Acid Therapy Does Not Alter Lithocholic Acid Levels in Patients with Cystic Fibrosis with Associated Liver Disease

To evaluate the fasting and postprandial serum bile acid composition in patients with cystic fibrosis-associated liver disease (CFLD) after chronic administration of ursodeoxycholic acid (UDCA) (20mg/kg/day). The aim was to specifically focus on the extent of biotransformation of UDCA to its hepatotoxic metabolite, lithocholic acid, because of recent concerns regarding the safety of long-term, high-dose UDCA treatment for CFLD. Twenty patients with CFLD (median age 16years, range: 2.4-35.0) prescribed UDCA therapy for at least 2years were studied. Total and individual serum bile acids were measured by stable-isotope dilution mass spectrometry, in fasting and 2-hour postprandial samples taken during chronic UDCA (20mg/kg/day) administration. During chronic UDCA administration (median duration 8years, IQR: 6-16), UDCA became the predominant serum bile acid in all patients (median, IQR: 3.17, 1.25-5.56μmol/L) and chenodeoxycholic acid concentrations were greater than cholic acid (1.86, 1.00-4.70μmol/L vs 0.40, 0.24-2.71μmol/L). The secondary bile acids, deoxycholate and lithocholate, were present in very low concentrations in fasted serum (<0.05μmol/L). After UDCA administration, 2-hour postprandial concentrations of both UDCA and chenodeoxycholic acid significantly increased (P<.01), but no significant changes in serum lithocholic acid concentrations were observed. These data do not support recent suggestions that enhanced biotransformation of UDCA to the hepatotoxic secondary bile acid lithocholic occurs when patients with CFLD are treated with relatively high doses of UDCA.

Clinical Course Following Partial External Biliary Diversion for Progressive Familial Intrahepatic Cholestasis 1: A Report of Two Patients

AIM: To better understand the effect of partial external biliary diversion (PEBD) in patients with progressive familial intrahepatic cholestasis 1 (PFIC1). MATERIALS AND METHODS: We analyzed quantitative changes in the concentrations of individual bile acids in serum, urine, and biliary bile, and concomitant changes in symptoms such as pruritus, in 2 patients whose PFIC1 clinically evolved to resemble the course of benign recurrent intrahepatic cholestasis (BRIC) upon treatment with PEBD. RESULTS: Patient 1 showed good therapeutic effect after PEBD including improved liver function test results and decreased total bile acids in serum, as well as decreased pruritus. The cholic acid (CA)/chenodeoxycholic acid (CDCA) ratio in biliary bile also decreased. Patient 2, however, experienced little decrease in pruritus after PEBD, and showed no clear change in the CA/CDCA ratio. Nonetheless, this patient’s course did not rapidly worsen. CONCLUSION: In PFIC1, increased bile secretion and a decreased CA/CDCA ratio in biliary bile may be the most important responses after PEBD. Relief of pruritus is also an important sign of therapeutic effect. Moreover, progression of symptoms in PFIC1 sometimes can be delayed by PEBD, resulting in a relatively mild BRIC-like course, even when the CA/CDCA ratio and pruritus show little change. However, mechanisms underlying clinical benefits remain obscure.

Tu1956 Ursodeoxycolic Acid in Primary Sclerosing Cholangitis: Does Its Effect on Individual Serum Bile Acids Explain Its Limited Benefit?

Tu1956 Ursodeoxycolic Acid in Primary Sclerosing Cholangitis: Does Its Effect on Individual Serum Bile Acids Explain Its Limited Benefit?

血中胆汁酸分画抽出操作におけるAmberlite XAD2とAmberlite XAD7の比較研究

血中胆汁酸分画抽出操作におけるAmberlite XAD2とAmberlite XAD7の比較研究

Significance of Serum Bile Acids in Small Bowel Allograft Rejection in Pigs

To examine changes in individual bile acids in serum in a pig model of allogenic small bowel transplantation. Seventeen pigs were divided into two groups: group 1 (n=10), controls; group 2 (n=7), allotransplantation, nonimmunosuppressed recipients. Both groups received a segmental intestine. Intestinal specimens for histologic studies were obtained at the end of cold flushing (T0) and on postoperative day 8 (T1). Total and individual bile acid concentrations were measured in serum samples taken at T0 and T1. All animals survived until the end of the study. In group 1, intestinal histology revealed no significant changes between T0 and T1 specimens. In contrast, in group 2, graft histology revealed moderate to severe rejection at T1 in all specimens. In contrast to group 1, serum levels of total bile acids increased significantly in group 2 at T1 compared with baseline (P=0.001). The increase was due to secondary bile acids which were significantly higher at T1 compared with baseline (P=0.0003). In contrast, secondary bile acids increased but not significantly at T1 in group 1 compared with baseline (P=0.056). Our study suggests that total and secondary serum bile acids may be a useful diagnostic tool for the diagnosis of acute intestinal rejection.

特異な血清胆汁酸分画異常を示し, 胆管炎併発時にCA19-9異常高値を呈した原発性硬化性胆管炎の1例

特異な血清胆汁酸分画異常を示し, 胆管炎併発時にCA19-9異常高値を呈した原発性硬化性胆管炎の1例

Bile acid profiles by capillary electrophoresis in intrahepatic cholestasis of pregnancy

ICP (intrahepatic cholestasis of pregnancy) is characterized by pruritus and biochemical cholestasis, including raised SBAs (serum bile acids) and, usually, elevated aminotransferases levels. However, AHP (asymptomatic hypercholanaemia of pregnancy) is defined as the presence of total SBA levels above the cut-off value (11 microM) in healthy pregnant women, thus elevation of total SBAs do not necessarily reflect an ICP condition. The aim of the present study was to describe clinical, obstetric, perinatal and biochemical findings, as well as the SBA profile, in pregnant women studied in the third trimester of pregnancy in order to define characteristic patterns of individual bile acids that enable women with ICP to be distinguished from AHP and healthy pregnancies. Free and conjugated ursodeoxycholic (UDCA), cholic (CA), lithocholic (LCA), deoxycholic (DCA) and chenodeoxycholic (CDCA) acids were evaluated by CE (capillary electrophoresis) in 41 patients (15 of them simultaneously by HPLC), in 30 healthy pregnant women and in 10 non-pregnant women. A highly significant correlation between CE and HPLC for total SBAs (r=0.990) and for individual SBAs was found. Normal pregnant women had higher total SBA levels than non-pregnant women (due to an increase in taurine-conjugated dihydroxy SBAs). Women with ICP had higher levels of total SBAs, the free/conjugated ratio, LCA, CA, CDCA and DCA than normal pregnant women. Newborns from women with ICP had lower birth weight and gestational age. Women with AHP had higher levels of conjugated dihydroxy SBAs than normocholanaemic patients, without any evidence of a clinical difference. In conclusion, the present study has shown a clear difference in SBA profiles between ICP and normal pregnancies (including AHP), involving a shift towards a characteristic hydrophobic composition in women with ICP.

Liver transplantation and bile analysis: a parallel evolution.

Liver transplantation and bile analysis: a parallel evolution.

Raised concentration of serum bile acids following occupational exposure to halogenated solvents, 1,1,2-trichloro-1,2,2-trifluoroethane and trichloroethylene.

The objectives of this study were threefold. First, to examine the hepatic effects of occupational exposure to 1,1,2-trichloro-1,2,2-trifluoroethane (FC 113) using conventional and newer tests (serum bile acids) of hepatobiliary function. Second, to assess the effects of altered work practices that included a reduced exposure to a different halogenated solvent (trichloroethylene) on the same parameters of liver function; and finally, to gather further data to support or refute the contention that serum bile acid (SBA) levels could provide a sensitive biological marker of exposure to these solvents. Two groups of workers (control and exposed) in an Australian steel industry participated in the study. The exposed group (n = 5-6) comprised individuals who had either exposure to FC 113 (68.2 +/- 12.6 ppm) or trichloroethylene (8.9 +/- 3.1 ppm) during the application of these solvents in a cleaning procedure, whereas the control group (n = 7-11) was composed of non-solvent-exposed office workers in the same company. The initial investigation involved exposure to FC 113 while a follow-up study was undertaken after changes in work practices were made including replacement of FC 113 with trichloroethylene (TRI). Standard liver function tests and individual serum bile acids (ISBA) were measured before and after exposure to solvents and simultaneously in the control subjects by enzymatic methods and high performance liquid chromatography (HPLC), respectively. Statistical analysis of the data showed a significant increase in the concentration of total serum bile acids (TSBA), some of the subgroups of SBA, and a few of the ISBA in workers after a period of exposure to FC 113. After TRI replaced FC 113 together with other changes in work practices to give substantial reduction in exposure to solvent, a repeat study also found elevated SBA after the cleaning procedure but to a lesser extent. No other indications of adverse liver effects, as measured by conventional parameters of hepatobiliary function, were detected. Exposure to FC 113 was clearly associated with a significant rise in SBA levels, which are sensitive indicators of liver function. This finding is consistent with, and provides further support for, our previous investigations on chlorinated aliphatic hydrocarbon solvents which showed that SBA levels are a sensitive biological marker of exposure to these solvents. Changes in work practices including replacement of FC 113 resulted in a reduced effect on SBA, consistent with lower exposures.