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Thirteen breast-fed one-month-old infants with prolonged jaundice not due to known causes were included in this study. All infants were investigated at one and twelve months of age. Serum concentrations of total (TB) and conjugated bilirubin (CB), aspartate (ASAT) and alanine aminotransferase (ALAT), alkaline phosphatase (AP), alpha-1-antitrypsin (alpha-1-AT), alpha-1-fetoprotein (AFP) and the two primary bile acids; cholic (CA) and chenodeoxycholic acid (CDCA) were determined at both ages. The Pi-phenotype of alpha-1-AT was determined at the age of twelve months. The serum concentrations of TB, CB, AP and AFP were elevated at the age of one month but were normal at the age of twelve months. No changes in the serum concentrations of ASAT or ALAT were observed between one and twelve months of age, and the values were within the reference ranges. The serum concentrations of alpha-1-AT were within the reference range at both ages. Two infants were heterozygous for MZ, and they had normal serum alpha-1-AT concentrations. The serum concentrations of CA and CDCA were elevated at the age of one month and were still significantly elevated at the age of twelve months indicating that the infants had slight cholestasis at the age of one month, and that the cholestasis had largely subsided by the end of the first year of life.
Investigations on the cholic acid CoA ligase activity of rat liver microsomes were made possible by the development of a rapid, sensitive radiochemical assay based on the conversion of [3H]choloyl-CoA. More than 70% of the rat liver cholic acid CoA ligase activity was associated with the microsomal subcellular fraction. The dependencies of cholic acid CoA ligase activity on pH, ATP, CoA, Triton WR-1339, acetone, ethanol, magnesium, and salts were investigated. The hypothesis that the long chain fatty acid CoA ligase activity and the cholic acid CoA ligase activity are catalyzed by a single microsomal enzyme was investigated. The ATP, CoA, and cholic (palmitic) acid kinetics neither supported nor negated the hypothesis. Cholic acid was not an inhibitor of the fatty acid CoA ligase and palmitic acid was not a competitive inhibitor of the cholic acid CoA ligase. The cholic acid CoA ligase activity utilized dATP as a substrate more effectively than did the fatty acid CoA ligase activity. The cholic acid and fatty acid CoA ligase activities appeared to have different pH dependencies, differed in thermolability at 41 degrees, and were differentially inactivated by phospholipase C. Moreover, fatty acid CoA ligase activity was present in microsomal fractions from all rat organs tested while cholic acid CoA ligase activity was detected only in liver microsomes. The data suggest that separate microsomal enzymes are responsible for the cholic acid and the fatty acid CoA ligase activities in liver.
In vitro cholic acid (CA) transformation by mixed fecal culture was investigated. Concentrations of glucose, peptone, and yeast extract in the medium and the initial pH of the medium markedly affected the CA transformation. Yeast extract enhanced the transformation, whereas high concentrations of glucose and peptone inhibited it. When the initial pH of the medium was below 6.5, CA was converted to 7-keto-deoxycholic acid (7KD), and formation of deoxycholic acid (DC) was not observed. In contrast, with an initial pH of 7.0, about 60% of the CA was converted to 7KD after 3 days of incubation, and then DC gradually formed after 4 days of incubation, following the disappearance of 7KD. The formation of DC in the cultured samples was paralleled in each case by disappearance of 7KD. In pure culture systems, Escherichia coli and some strains of Bacteroides formed 7KD from CA. No DC formation was observed in pure cultures of any of the strains examined.
Concentrations of two primary bile acids (cholic and chenodeoxycholic acids) were determined by radioimmunoassay in the serum of infants and children at ages ranging from 1 hour to 15 years. The same bile acids were also measured in umbilical cord serum. Concentrations of the primary bile acids were significantly higher in the serum of 1-hour old infants than those in the umbilical cord serum or the peripheral vein serum of adults. The levels of cholic and chenodeoxycholic acid remained high until the age of 6 months, being about 5-fold higher than those in the sera of adults. Primary bile acid concentrations reached the adult level by the age of 1-2 years. These results indicate that developmental changes occur in the metabolism and excretion of bile acids in man. The relatively high concentrations of the primary bile acids in serum during the first 6 months of life suggest that up to this age, the mature ability of the liver to excrete the bile salts into the bile and/or to clear them from the circulation has not yet been reached.
A procedure is described for the simultaneous determination of cholic acid and chenodeoxycholic acid pool sizes and fractional turnover rates. After oral administration of known amounts of 11,12-dideuterated chenodeoxycholic acid and 2,2,4,4-tetradeuterated cholic acid, the ratios of chenodeoxycholic acid-D2/chenodeoxycholic acid and cholic acid-D4/cholic acid are measured in consecutive serum samples, after which fractional turnover rates and pool sizes of chenodeoxycholic acid and cholic acid are determined arithmetically. In 7 healthy volunteers pool sizes for chenodeoxycholic acid and cholic acid were 22.9 +/- 7.8 and 24.1 +/- 11.7 mumol/kg, respectively. The corresponding values for the fractional turnover rates were 0.23 +/- 0.10 and 0.29 +/- 0.12/day. After oral administration of the labelled bile acids in capsule, the obtained pool sizes were significantly higher than after administration in a bicarbonate solution. Bile acid kinetics were also performed in a patient suffering from a cholesterol synthesis deficiency and in a patient very likely suffering from a bile acid synthesis deficiency. Furthermore, the kinetics of the intestinal absorption and hepatic clearance of unconjugated bile acids have been investigated in 2 healthy subjects.
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Bile acid pool size and kinetics were determined in 17 patients with cirrhosis and 11 patients without liver disease and correlated with the severity of liver disease as determined by the usual clinical and laboratory criteria. In order to assess the severity of liver disease, a grading system was devised which assigned numerical values to various clinical signs and laboratory results. The total clinical score and the patients were divided into two groups of advanced (7-18 points) or mild (1-6 points) cirrhosis. The clinical rating was then correlated with the various aspects of bile acid metabolism. Cholic acid synthesis was markedly reduced in the early stages of cirrhosis and continued to decrease with the advancement of the liver disease. There was an inverse correlation between synthesis of cholic acid and the severity of cirrhosis. Nine of the 10 patients with advanced cirrhosis and a very low cholic acid synthetic rate (average 68 mg per day) died within one to 13 months from the start of the study. Patients with mild cirrhosis also had significantly reduced cholic acid synthesis (average 152 mg per day) but they all were well and alive three to 23 months after the study. In contrast, chenodeoxycholic acid synthesis was not markedly affected in either patients with mild or advanced cirrhosis. There was also a high degree of correlation between the fractional daily turnover rate of cholic acid and the severity of liver disease. The fractional daily turnover rate of cholic acid was greatly reduced (50%) in patients with advanced cirrhosis. Deoxycholic acid was reduced in patients with mild cirrhosis and virtually absent from the bile of patients with advanced cirrhosis. The findings of the present report provide evidence that cholic acid synthesis is a sensitive indicator of the hepatocellular damage, whereas chenodeoxycholic acid synthesis is relatively unaffected by cirrhosis. The selective alteration in cholic acid synthesis probably resides in a deficiency of one or more enzymes regulating the formation of the 3-keto, 7 alpha, 12 alpha-dihydroxy precursor of cholic acid.
Bile acid kinetics were evaluated after oral administration of 14C-labelled cholic acid in ten normal subjects and two patients with severe bile acid malabsorption. The faecal 14C excretion was measured during the turnover study. Cholic acid synthesis rate was significantly correlated to 14C output in stools. The faecal radioisotope excretion is recommended for detection and semi-quantitation of bile acid malabsorption.
The plasma bile acid profiles of three children with the inherited metabolic disorder, infantile Refsum's disease, were found to contain 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid. This intermediate in the synthesis of cholic acid was identified by combined gas-liquid chromatography-mass spectrometry and accounted for approximately 25% of the total bile acids which were present at elevated concentrations in plasma. Infantile Refsum's disease appears to share several biochemical features with the cerebro-hepato-renal syndrome (Zellweger's disease), including abnormal bile acid metabolism.
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To investigate the presence of 7 alpha-dehydroxylase activity on bile acids in the bacterial strains of fermented milk products, 46 strains of Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus acidophilus, Lactobacillus gasseri, Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium infantis, Bifidobacterium longum, Lactococcus lactis spp. lactis, and Streptococcus salivarius spp. thermophilus were tested for their ability to produce deoxycholic acid from cholic acid. The production of deoxycholic acid was quantitatively measured by radiochromatographic analysis in anaerobically prepared washed whole resting cells and by HPLC analysis in growing cultures. Resting whole cells from a positive control strain, Eubacterium lentum-like strain c-25, converted 81.7% of .2 mM cholic acid to deoxycholic acid and 3.7% to 7-keto-deoxycholic acid, when the cell suspension was incubated anaerobically at a concentration of 2 mg of protein/ml for 4 h at pH 7.3. However, none of the test strains investigated in this study was able to transform cholic acid under the same conditions. In growing cultures, 91.5% of 150 micrograms/ml of cholic acid was transformed to deoxycholic acid and 1.1% to 7-keto-deoxycholic acid by E. lentum-like c-25 after a 7-d anaerobic incubation. None of the test strains showed production of either deoxycholic acid or 7-keto-deoxycholic acid as growing cultures.
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A method for the extraction of bile acids from serum is described that enables the stable isotopic content of chenodeoxycholic acid and cholic acid to be determined accurately to levels as low as the natural 13C abundance. The method uses Sep-Pak C18 reverse phase cartridges both for extraction and purification procedures. Free bile acids, bile acid conjugates, and 3-monosulfated bile acid conjugates are recovered in high yield from the Sep-Pak in methanol-water 75:25 after first removing impurities with hexane and methanol-water 40:60 washes. Other important features of the method include the use of enzymatic rather than alkaline hydrolysis of bile acid conjugates, the use of ammonia as the reagent gas for chemical ionization mass spectrometric measurement of isotopic ratios, and the exclusion of all extraneous components in the final sample from the ion source. This method should be applicable to kinetic studies of bile acids using bile acids labeled with stable isotopes and serum measurements, and provides an alternative sampling point in the enterohepatic circulation to conventional duodenal bile samples requiring intubation.
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PURPOSE: To investigate the ability of the human intestinal bile acid transporter to transport cholic acid conjugates with potential HIV-1 protease inhibitory activity. METHODS: Cholic acid was conjugated at the 24 position of the sterol nucleus with various amino acids and amino acid analogs. The CaCo-2 cell line was used as a model to investigate the interaction of these bile acid conjugates with the human intestinal bile acid transporter. Interaction between the carrier and the conjugates was quantified by inhibition of taurocholic acid transport and confirmed by transport of radiolabelled conjugates in this cell line. RESULTS: The highest interaction with the transporter, as quantified by inhibition of taurocholic acid transport, occurred when a single negative charge was present around the 24 to 29 region of the sterol nucleus. A second negative charge or a positive charge significantly reduced the interaction. Transport of radiolabelled cholyl-L-Lys-epsilon-tBOC ester and cholyl-D-Asp-beta-benzyl ester was inhibited by taurocholic acid. Of all tested compounds, only cholyl-D-Asp-beta-benzyl ester showed modest HIV-1 protease inhibitory activity with an IC50 of 125 microM. CONCLUSIONS: Cholic acid-amino acid conjugates with appropriate stereochemistry are recognized and transported by the human bile acid transporter and show modest HIV-1 protease inhibitory activity. Transport of these conjugates by the bile acid carrier is influenced by charge and hydrophobicity around the 24 position of the sterol nucleus.