Concentrations Of Primary Bile Acids Research Articles

Determination of bile acids by hollow fibre liquid-phase microextraction coupled with gas chromatography

A method based on hollow-fibre liquid phase microextraction combined with gas chromatography was developed for determination of specific bile acids in caecal materials of rats. Nine unconjugated bile acids, including the primary bile acids (cholic acid, chenodeoxycholic acid and α-muricholic acid) and the secondary bile acids (lithocholic acid, deoxycholic acid, ursodeoxycholic acid, hyodeoxycholic acid, β-muricholic acid and ω-muricholic acid) were quantified. Extraction conditions were evaluated, including: sample pH, type of organic solvent and amount of caecal material to be extracted. To compensate for sample matrix effects during extraction the method of standard addition was applied. The satisfactory linearity (r(2)>0.9840), high recovery (84.2-108.7%) and good intra-assay (6.3-10.6%) and inter-assay (6.9-11.1%) precision illustrated the good performance of the present method. The method is rapid, simple and capable of detecting and determining bile acids with limit of detection (LOD) ranged from 0.002 to 0.067μg/mL and limits of quantification (LOQ) varied from 0.006 to 0.224μg/mL. The results indicated that the concentration of some secondary bile acids, which usually are associated with health problems, were lower in rats fed with fermentable dietary fibre compared with a fibre free control diet, while the concentration of primary bile acids, usually connected with positive health effects, were higher in rats fed with diets containing dietary fibre. Of the dietary fibres, guar gum and to some extent the mixture of pectin+guar gum had the most positive effects. Thus, it was concluded that the composition of bile acids can be affected by the type of diet.

Rapid quantification of conjugated and unconjugated bile acids and C27 precursors in dried blood spots and small volumes of serum

The aim of the study was to develop a method for fast and reliable diagnosis of peroxisomal diseases and to facilitate differential diagnosis of cholestatic hepatopathy. For the quantification of bile acids and their conjugates as well as C(27) precursors di- and trihydroxycholestanoic acid (DHCA, THCA), in small pediatric blood samples we combined HPLC separation on a reverse-phase C18 column with ESI-MS/MS analysis in the negative ion mode. Analysis was done with good precision (CV 3,7%-11.1%) and sufficient sensitivity (LOQ: 11-91 nmol/L) without derivatization. Complete analysis of 17 free and conjugated bile acids from dried blood spots and 10 microL serum samples, respectively, was performed within 12 min. Measurement of conjugated primary bile acids plus DHCA and THCA as well as ursodeoxycholic acid was done in 4.5 min. In blood spots of healthy newborns, conjugated primary bile acids were found in the range of 0.01 to 2.01 micromol/L. Concentrations of C(27) precursors were below the detection limit in normal controls. DHCA and THCA were specifically elevated in cases of peroxysomal defects and one Zellweger patient.

Physiological Effects of Extraction Juices from Apple, Grape, and Red Beet Pomaces in Rats

In comparison to classical fruit juice processing, polyphenols and dietary fiber can be extracted from pomace by means of pectinases and cellulases. In the present study, rats were fed with such produced extraction juices from apples, grapes, and red beets as drinking fluids instead of water for 4 weeks to evaluate their physiological effects. In all test groups, the intake of extraction juices was greater as compared to control (water intake), resulting in a higher urine excretion. In the apple and grape group, pH values in feces was lower than control. Administration of extraction juices from apples increased fecal counts of Lactobacillus and Bifidobacterium. More acetate and total short-chain fatty acids appeared in intestinal contents of the apple and red beet group. Furthermore, the intestinal contents of test groups contained higher concentrations of primary bile acids, cholesterol, and cholesterol metabolites but lower concentrations of secondary bile acids. The total amount of steroids excreted by these groups was also greater than control. Quercetin and isorhamnetin appeared in urine of rats fed extraction juices from apples and grapes; in urine of the former group, phloretin was found also. Administration of the extraction juices, enriched in secondary plant metabolites and dietary fiber, resulted in beneficial nutritional effects in rats.

Effects of resistant starch on the colon in healthy volunteers: possible implications for cancer prevention

Recent evidence suggests that resistant starch (RS) is the single most important substrate for bacterial carbohydrate fermentation in the human colon. During two 4-wk periods. 12 healthy volunteers consumed a controlled basal diet enriched with either amylomaize starch (55.2 +/- 3.5 g RS/d; high-RS diet) or available cornstarch (7.7 +/- 0.3 g RS/d; low-RS diet). Approximately 90% of the RS consumed disappeared during intestinal passage; increased fermentation was verified by elevated breath-hydrogen excretion. During the high-RS diet, fecal wet and dry weight increased 49% and 56%, respectively (P < or = 0.005), whereas stool water content did not change significantly. Fecal concentrations and daily excretion of short-chain fatty acids were not different in the two study periods. During the high-RS diet, bacterial beta-glucosidase activity decreased by 26% (P < or = 0.05). Fecal concentrations of total and secondary bile acids were significantly lower during the high-RS than during the low-RS period [a decrease of 30% (P < or = 0.05) and 32% (P < or = 0.01), respectively, in total and secondary bile acids] whereas concentrations of primary bile acids were unaffected by RS consumption. During the high-RS diet, fecal concentrations of total neutral sterols decreased by 30% (P < or = 0.005) and fecal concentrations of 4-cholesten-3-one decreased by 36% (P < or = 0.05). These data suggest that RS has potentially important effects on bacterial metabolism in the human colon that may be relevant for cancer prevention.

Calcium Supplementation Modifies the Relative Amounts of Bile Acids in Bile and Affects Key Aspects of Human Colon Physiology

Use of calcium supplements has increased dramatically in recent years yet little is known about the effect of calcium supplementation on colon physiology. We supplemented 22 individuals with a history of resected adenocarcinoma of the colon, but currently free of cancer, with 2000 or 3000 mg calcium for 16 wk. The effects of supplementation on duodenal bile acids and important fecal characteristics including total fecal output, wet and dry weight, pH, bile acids (in solids and in fecal water), and concentrations and total excretion of calcium, magnesium, phosophates (organic and inorganic), unesterified fatty acids and total fat were determined. Calcium supplementation significantly decreased the proportion of water in the stool (P = 0.03), doubled fecal excretion of calcium (P = 0.006), and increased excretion of organic phosphate (P = 0.035) but not magnesium. Calcium supplementation significantly decreased the proportion of chenodeoxycholic acid in bile (P = 0.007) and decreased the ratio of lithocholate to deoxycholate in feces (P = 0.06). The concentration of primary bile acids in fecal water decreased after 16 wk Ca supplementation. Together with other reports of a “healthier” bile acid profile with respect to colon cancer when changes such as those observed in this study were achieved, these results suggest a protective effect of calcium supplementation against this disease.

Cyclosporin A-mediated cholestasis in patients with chronic hepatitis after heart transplantation

Viral chronic hepatitis often occurs in heart transplant recipients receiving cyclosporin. This essential immunosuppressive drug may induce cholestasis. We investigated the effect of treatment with cyclosporin on serum conjugated bile acids in patients with chronic hepatitis developing after heart transplantation. Fifty-nine patients were studied: 17 with chronic hepatitis, 15 heart transplant patients with normal alanine aminotransferase activity, and 27 heart transplant patients with chronic hepatitis, the last two groups receiving cyclosporin. Hepatic biochemical tests and total bile acid concentration were determined on fasting blood samples. The individual glyco- and tauroconjugated bile acids were quantified by high-performance liquid chromatography and direct spectrometry. In patients taking cyclosporin the bilirubin concentration and the alkaline phosphatase activity were increased only when hepatitis was present, in association with a slight increase in cholic acid level (5.13 microM vs. 0.68 microM; P < 0.01). Conjugated lithocholate concentration was dramatically higher when hepatitis and immunosuppression with cyclosporin were associated (1.17 microM vs. 0.03 and 0.04 microM; P < 0.01). Chenodeoxycholate was the main circulating bile acid only in the heart transplant patients treated with cyclosporin but without hepatitis. These results suggest that the mechanisms which explain the cyclosporin-associated modifications of the bile acid pool are different according to the presence or absence of hepatitis. The occurrence of hepatitis in patients on cyclosporin led to an increase in serum lithocholate and primary bile acid concentrations. Further studies are required to assess the effect of ursodeoxycholic acid for this cholestasis.

Serum Primary Bile Acids in the Course of Celiac Disease in Children

Scrum concentrations of primary bile acids (BAs) were determined in the course of celiac disease and in healthy age‐matched controls. Determinations of BAs were made by radioimmunoassays after an overnight fasting and for 4 h postprandially after intake of a standardized test meal. In untreated celiac disease presenting with subtotal villous atrophy, peak concentrations of primary BAs were significantly delayed and serum levels were significantly higher than in controls. Small but significant abnormalities persisted after a period of gluten‐free diet despite a normalization of mucosal morphology. Slightly pathological standard liver function tests in five patients were related to increased fasting levels but not to the postprandial pattern of BAs, indicating that the observed abnormalities postprandially were not related to liver disease. Further studies simultaneously focusing on deconjugation mechanisms, absorption, and pool sizes of BAs are required to explain the postprandial BA pattern under the course of celiac disease.

Serum primary bile acids in the course of celiac disease in children.

Serum concentrations of primary bile acids (BAs) were determined in the course of celiac disease and in healthy age-matched controls. Determinations of BAs were made by radioimmunoassays after an overnight fasting and for 4 h postprandially after intake of a standardized test meal. In untreated celiac disease presenting with subtotal villous atrophy, peak concentrations of primary BAs were significantly delayed and serum levels were significantly higher than in controls. Small but significant abnormalities persisted after a period of gluten-free diet despite a normalization of mucosal morphology. Slightly pathological standard liver function tests in five patients were related to increased fasting levels but not to the postprandial pattern of BAs, indicating that the observed abnormalities postprandially were not related to liver disease. Further studies simultaneously focusing on deconjugation mechanisms, absorption, and pool sizes of BAs are required to explain the postprandial BA pattern under the course of celiac disease.

Effect of phototherapy and exchange transfusion on primary bile acids in the serum of hyperbilirubinaemic newborns.

Serum primary bile acid (cholic (CA) and chenodeoxycholic (CDCA) acid) concentrations were measured in 14 preterm and 11 full-term hyperbilirubinaemic newborns at the beginning and end of, and 24 and 72 hours following phototherapy. Only in the preterm newborns with gestational ages of 35-38 weeks there was a significant decrease of mean serum bile acid concentrations which could be shown 72 hours after the beginning of phototherapy. It can be hypothesized that the decrease was a result of a direct effect of light on the excretory liver function. Serum CA and CDCA concentrations were also measured in 5 hyperbilirubinaemic newborns at the beginning and end, and 24, 48 and 72 hours after the end of exchange transfusion. Exchange transfusion caused a clear immediate decrease in the mean serum primary bile acid concentrations. However, on day 2 after exchange transfusion the mean serum concentration of CA was about 150% and that of CDCA about 110% of the initial values. The most hyperbilirubinaemic newborns had extremely high primary bile acid serum concentrations before therapy. As bile acids compete with bilirubin for albumin binding it should be considered whether high bile acids in the serum of hyperbilirubinaemic newborns presuppose exchange transfusions.

Serum cholic acid and chenodeoxycholic acid concentrations in neonatal hyperbilirubinemia.

Primary bile acid concentrations were measured in serum of 332 newborns with neonatal hyperbilirubinemia (serum total bilirubin level greater than 200 mumol/l) and compared with those of 95 nonhyperbilirubinemic neonates (serum total bilirubin level less than 200 mumol/l). The serum concentrations (mumol/l; mean +/- SEM) for cholic acid (8.78 +/- 0.44) and chenodeoxycholic acid (10.5 +/- 0.68) were significantly higher (p less than 0.001) in the hyperbilirubinemic group than in the controls (7.16 +/- 0.48 and 6.67 +/- 0.48, respectively). 80 (24%) of the hyperbilirubinemic newborns had true cholestasis (serum levels of cholic and/or chenodeoxycholic acid higher than mean +/- 2 SD in the reference group). The ratio of cholic to chenodeoxycholic acid was significantly higher (p less than 0.05) in the cholestatic group than in the hyperbilirubinemic newborns without cholestasis. There was no significant differences in the serum concentrations of alkaline phosphatase or lactate dehydrogenase between the cholestatic and noncholestatic groups. In the hyperbilirubinemic newborns, the primary bile acids were indiscriminately raised. Only 8 infants from the 332 newborns had jaundice at the age of 1 month. Of these 8 infants only 2 had neonatal cholestatic hyperbilirubinemia. It thus appears that measurement of serum primary bile acid concentrations has only limited diagnostic value in assessing the severity or prognosis of neonatal hyperbilirubinemia.

Cholic acid and chenodeoxycholic acid concentrations in serum during infancy and childhood.

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.

Within-day fluctuations in serum bile-acid concentrations among normal control subjects and patients with hepatic disease.

Under carefully controlled conditions in a clinical research ward, conjugated primary bile-acid concentrations were measured by a 125I-radioimmunoassay every eight hours for four days in seven healthy control subjects and ten patients with hepatic disease (five with cirrhosis, three with primary biliary cirrhosis and two with sclerosing cholangitis). Two meals of approximately equal composition were consumed daily at 10 A.M. and 6 P.M., and blood was drawn at 4 A.M., 12 noon and 8 P.M.. With the exception of one patient, all subjects had greater postprandial than fasting serum bile-acid concentrations, with all healthy control subjects and most of those with hepatic disease showing evening values equal to or greater than the noon values. For the healthy control subjects, the mean values were 0.8, 1.4 and 1.9 microM, and for those with hepatic disease, 108, 140 and 133 microM. There were large fluctuations in serum bile acids (up to sevenfold) among patients with hepatic disease. These fluctuations were independently validated by finding corresponding changes in serum radioactivity derived from injection of a tracer (24-14C cholic acid) at the start of each study. To be consistent, especially for serial measurements, bile acids should be measured in blood taken at the same time of the day and at the same time relative to meals.

Bile Acids, Diarrhea, and Antibiotics: Data, Speculation, and a Unifying Hypothesis

The primary bile acid, chenodeoxycholic acid, and the secondary bile acid, deoxycholic acid, when present at a concentration of greater than 3 mM, induce salt and water secretion from the human colon and cause a marked increase in the permeability of the human colon to molecules of a molecular weight of 200-500 daltons. Scanning electron microscopy indicates that this action may be associated with tissue damage in some species. In the healthy individual, the primary bile acids, cholic and chenodeoxycholic acid, are dehydroxylated in the colon and are simultaneously precipitated from solution; at pH less than 7, deoxycholic and lithocholic acid are insoluble. In patients with bile acid diarrhea resulting from bile acid malabsorption, dehydroxylation is decreased, and the concentration of bile acids in the colon is markedly elevated. The major secretory bile acid in solution is chenodeoxycholic acid. Administration of cholestyramine, a resin that binds bile acid, reduces the elevated concentration of chenodeoxycholic acid and abolishes the diarrhea. These facts can be used to develop a unifying hypothesis which proposes that elevated concentrations of primary bile acids in the colon play a role in diarrhea and pseudomembranous colitis induced by clindamycin.