Vitamin D Receptor Deletion Changes Bile Acid Composition in Mice Orally Administered Chenodeoxycholic Acid.

The vitamin D receptor (VDR) is a nuclear receptor for the active form of vitamin D3 and also for the secondary bile acid lithocholic acid (LCA). The in vivo role of VDR in bile acid metabolism remains largely uncharacterized. We previously reported that pharmacological VDR activation enhances urinary bile acid excretion, particularly in mice fed chow supplemented with chenodeoxycholic acid (CDCA), which is metabolized to muricholic acid in mouse liver and is also converted to LCA by intestinal bacteria. In this study, we examined the effect of VDR deletion on bile acid composition utilizing VDR-knockout (VDR-KO) mice. VDR deletion did not change total bile acid levels in liver or feces of mice when fed standard chow supplemented with calcium, needed to prevent hypocalcemia in VDR-KO mice. Total bile acid levels in plasma and urine tended to be higher and lower, respectively, in VDR-KO mice. After feeding CDCA-supplemented chow, VDR-KO mice showed decreased hepatic, fecal and urinary total bile acid and CDCA levels compared to wild-type mice. Plasma total bile acids and LCA were relatively high in these mice. These results indicate that VDR deletion influences CDCA metabolism. VDR may play a role in the excretion of excess bile acids.

Qiang-Gan formula extract improves non-alcoholic steatohepatitis via regulating bile acid metabolism and gut microbiota in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Qiang-Gan formula is a traditional Chinese medicine formula, which has been widely used in treating liver diseases in China. AIM OF THE STUDY: To investigate the effect of Qiang-Gan formula extract (QGE) on non-alcoholic steatohepatitis (NASH) and its underlying possible mechanisms. MATERIALS AND METHODS: The high-performance liquid chromatography finger-print method was used for the quality control of chemical components in QGE. Methionine- and choline-deficient diet-induced NASH mice were administrated with QGE via gavage for four weeks. Phenotypic parameters including liver histological change as well as serum levels of alanine transaminase (ALT), aspartate transaminase (AST) were detected. Bile acid profile in the serum, liver and fecal samples was analyzed by gas chromatography-mass spectrometer technique, and fecal microbiota was detected by 16S rDNA sequencing. Expression of liver G protein-coupled bile acid receptor 1 (TGR5), farnesiod X receptor (FXR), tumor necrosis factor-α (TNF-α), interleukin 1ß (IL-1ß) as well as molecules in nuclear factor kappa B (NF-κB) pathway was assayed by immunohistochemistry staining, RT-qPCR, or Western blot, respectively. RESULTS: QGE alleviated liver inflammation, reduced serum ALT and AST levels and liver TNF-α and IL-1ß expression in NASH mice. It also decreased liver and serum BA concentration and increased fecal lithocholicacid (LCA) production in this animal model. QGE altered the structure of gut microbiota, predominantly increased LCA-producing bacteria Bacteroides and Clostridium in NASH mice. In addition, the expression of liver TGR5 but not FXR was increased, and the molecules in NF-κB pathway were decreased in QGE-treated NASH mice. CONCLUSIONS: QGE was effective in preventing NASH, possibly by regulation of gut microbiota-mediated LCA production, promotion of TGR5 expression and suppression of the NF-κB activation.

Lithocholic Acid Is a Vitamin D Receptor Ligand That Acts Preferentially in the Ileum.

The vitamin D receptor (VDR) is a nuclear receptor that mediates the biological action of the active form of vitamin D, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], and regulates calcium and bone metabolism. Lithocholic acid (LCA), which is a secondary bile acid produced by intestinal bacteria, acts as an additional physiological VDR ligand. Despite recent progress, however, the physiological function of the LCA−VDR axis remains unclear. In this study, in order to elucidate the differences in VDR action induced by 1,25(OH)2D3 and LCA, we compared their effect on the VDR target gene induction in the intestine of mice. While the oral administration of 1,25(OH)2D3 induced the Cyp24a1 expression effectively in the duodenum and jejunum, the LCA increased target gene expression in the ileum as effectively as 1,25(OH)2D3. 1,25(OH)2D3, but not LCA, increased the expression of the calcium transporter gene Trpv6 in the upper intestine, and increased the plasma calcium levels. Although LCA could induce an ileal Cyp24a1 expression as well as 1,25(OH)2D3, the oral LCA administration was not effective in the VDR target gene induction in the kidney. No effect of LCA on the ileal Cyp24a1 expression was observed in the VDR-null mice. Thus, the results indicate that LCA is a selective VDR ligand acting in the lower intestine, particularly the ileum. LCA may be a signaling molecule, which links intestinal bacteria and host VDR function.

Protective effects of yangonin from an edible botanical Kava against lithocholic acid-induced cholestasis and hepatotoxicity.

Accumulation of toxic bile acids in liver could cause cholestasis and liver injury. The purpose of the current study is to evaluate the hepatoprotective effect of yangonin, a product isolated from an edible botanical Kava against lithocholic acid (LCA)-induced cholestasis, and further to elucidate the involvement of farnesoid X receptor (FXR) in the anticholestatic effect using in vivo and in vitro experiments. The cholestatic liver injury model was established by intraperitoneal injections of LCA in C57BL/6 mice. Serum biomarkers and H&E staining were used to identify the amelioration of cholestasis after yangonin treatment. Mice hepatocytes culture, gene silencing experiment, real-time PCR and Western blot assay were used to elucidate the mechanisms underlying yangonin hepatoprotection. The results indicated that yangonin promoted bile acid efflux and reduced hepatic uptake via an induction in FXR-target genes Bsep, Mrp2 expression and an inhibition in Ntcp, all of which are responsible for bile acid transport. Furthermore, yangonin reduced bile acid synthesis through repressing FXR-target genes Cyp7a1 and Cyp8b1, and increased bile acid metabolism through an induction in gene expression of Sult2a1, which are involved in bile acid synthesis and metabolism. In addition, yangonin suppressed liver inflammation through repressing inflammation-related gene NF-κB, TNF-α and IL-1ß. In vitro evidences showed that the changes in transporters and enzymes induced by yangonin were abrogated when FXR was silenced. In conclusions, yangonin produces protective effect against LCA-induced hepatotoxity and cholestasis due to FXR-mediated regulation. Yangonin may be an effective approach for the prevention against cholestatic liver diseases.

Reduction in hepatic secondary bile acids caused by short-term antibiotic-induced dysbiosis decreases mouse serum glucose and triglyceride levels.

Antibiotic-caused changes in intestinal flora (dysbiosis) can have various effects on the host. Secondary bile acids produced by intestinal bacteria are ligands for specific nuclear receptors, which regulate glucose, lipid, and drug metabolism in the liver. The present study aimed to clarify the effect of changes in secondary bile acids caused by antibiotic-induced dysbiosis on the host physiology, especially glucose, lipid, and drug metabolism. After oral administration of non-absorbable antibiotics for 5 days, decreased amounts of secondary bile acid-producing bacteria in faeces and a reduction in secondary bile acid [lithocholic acid (LCA) and deoxycholic acid (DCA)] levels in the liver were observed. Serum glucose and triglyceride levels were also decreased, and these decreases were reversed by LCA and DCA supplementation. Quantitative proteomics demonstrated that the expression levels of proteins involved in glycogen metabolism, cholesterol, bile acid biosynthesis, and drug metabolism (Cyp2b10, Cyp3a25, and Cyp51a1) were altered in the liver in dysbiosis, and these changes were reversed by LCA and DCA supplementation. These results suggested that secondary bile acid-producing bacteria contribute to the homeostasis of glucose and triglyceride levels and drug metabolism in the host, and have potential as therapeutic targets for treating metabolic disease.

Pharmacological evaluation of new bioavailable small molecules targeting Eph/ephrin interaction.

Eph/ephrin system is an emerging target for cancer therapy but the lack of potent, stable and orally bioavailable compounds is impairing the development of the field. Since 2009 our research group has been devoted to the discovery and development of small molecules targeting Eph/ephrin system and our research culminated with the synthesis of UniPR129, a potent but problematic Eph/ephrin antagonist. Herein, we describe the in vitro pharmacological properties of two derivatives (UniPR139 and UniPR502) stemmed from structure of UniPR129. These two compounds acted as competitive and reversible antagonists of all Eph receptors reducing both ephrin-A1 and -B1 binding to EphAs and EphBs receptors in the low micromolar range. The compounds acted as antagonists inhibiting ephrin-A1-dependent EphA2 activation and UniPR139 exerted an anti-angiogenic effect, inhibiting HUVEC tube formation in vitro and VEGF-induced vessel formation in the chick chorioallantoic membrane assay. Finally, the oral bioavailability of UniPR139 represents a step forward in the search of molecules targeting the Eph/ephrin system and offers a new pharmacological tool useful for future in vivo studies.

The Yin and Yang of bile acid action on tight junctions in a model colonic epithelium.

Gastrointestinal epithelial barrier loss due to tight junction (TJ) dysfunction and bile acid-induced diarrhea are common in patients with inflammatory diseases. Although excess colonic bile acids are known to alter mucosal permeability, few studies have compared the effects of specific bile acids on TJ function. We report that the primary bile acid, chenodeoxycholic acid (CDCA), and its 7α-dehydroxylated derivative, lithocholic acid (LCA) have opposite effects on epithelial integrity in human colonic T84 cells. CDCA decreased transepithelial barrier resistance (pore) and increased paracellular 10 kDa dextran permeability (leak), effects that were enhanced by proinflammatory cytokines (PiC [ng/mL]: TNFα[10] + IL-1ß[10] + IFNγ[30]). CDCA reversed the cation selectivity of the monolayer and decreased intercellular adhesion. In contrast, LCA alone did not alter any of these parameters, but attenuated the effects of CDCA ± PiC on paracellular permeability. CDCA, but not PiC, decreased occludin and not claudin-2 protein expression; CDCA also decreased occludin localization. LCA ± CDCA had no effects on occludin or claudin expression/localization. While PiC and CDCA increased IL-8 production, LCA reduced both basal and PiC ± CDCA-induced IL-8 production. TNFα + IL1ß increased IFNγ, which was enhanced by CDCA and attenuated by LCA CDCA±PiC increased production of reactive oxygen species (ROS) that was attenuated by LCA Finally, scavenging ROS attenuated CDCA's leak, but not pore actions, and LCA enhanced this effect. Thus, in T84 cells, CDCA plays a role in the inflammatory response causing barrier dysfunction, while LCA restores barrier integrity. Understanding the interplay of LCA, CDCA, and PiC could lead to innovative therapeutic strategies for inflammatory and diarrheal diseases.

Epigallocatechin gallate induces a hepatospecific decrease in the CYP3A expression level by altering intestinal flora.

In previous studies, we showed that a high-dose intake of green tea polyphenol (GP) induced a hepatospecific decrease in the expression and activity of the drug-metabolizing enzyme cytochrome P450 3A (CYP3A). In this study, we examined whether this decrease in CYP3A expression is induced by epigallocatechin gallate (EGCG), which is the main component of GP. After a diet containing 1.5% EGCG was given to mice, the hepatic CYP3A expression was measured. The level of intestinal bacteria of Clostridium spp., the concentration of lithocholic acid (LCA) in the feces, and the level of the translocation of pregnane X receptor (PXR) to the nucleus in the liver were examined. A decrease in the CYP3A expression level was observed beginning on the second day of the treatment with EGCG. The level of translocation of PXR to the nucleus was significantly lower in the EGCG group. The fecal level of LCA was clearly decreased by the EGCG treatment. The level of intestinal bacteria of Clostridium spp. was also decreased by the EGCG treatment. It is clear that the hepatospecific decrease in the CYP3A expression level observed after a high-dose intake of GP was caused by EGCG. Because EGCG, which is not absorbed from the intestine, causes a decrease in the level of LCA-producing bacteria in the colon, the level of LCA in the liver decreases, resulting in a decrease in the nuclear translocation of PXR, which in turn leads to the observed decrease in the expression level of CYP3A.

Binding of bile acids by pastry products containing bioactive substances during in vitro digestion.

The modern day consumer tends to choose products with health enhancing properties, enriched in bioactive substances. One such bioactive food component is dietary fibre, which shows a number of physiological properties including the binding of bile acids. Dietary fibre should be contained in everyday, easily accessible food products. Therefore, the aim of this study was to determine sorption capacities of primary bile acid (cholic acid - CA) and secondary bile acids (deoxycholic - DCA and lithocholic acids - LCA) by muffins (BM) and cookies (BC) with bioactive substances and control muffins (CM) and cookies (CC) in two sections of the in vitro gastrointestinal tract. Variations in gut flora were also analysed in the process of in vitro digestion of pastry products in a bioreactor. Enzymes: pepsin, pancreatin and bile salts: cholic acid, deoxycholic acid and lithocholic acid were added to the culture. Faecal bacteria, isolated from human large intestine, were added in the section of large intestine. The influence of dietary fibre content in cookies and concentration of bile acids in two stages of digestion were analysed. Generally, pastry goods with bioactive substances were characterized by a higher content of total fibre compared with the control samples. These products also differ in the profile of dietary fibre fractions. Principal Component Analysis (PCA) showed that the bile acid profile after two stages of digestion depends on the quality and quantity of fibre. The bile acid profile after digestion of BM and BC forms one cluster, and with the CM and CC forms a separate cluster. High concentration of H (hemicellulose) is positively correlated with LCA (low binding effect) and negatively correlated with CA and DCA contents. The relative content of bile acids in the second stage of digestion was in some cases above the content in the control sample, particularly LCA. This means that the bacteria introduced in the 2nd stage of digestion synthesize the LCA.

Coenzyme Q in pregnant women and rats with intrahepatic cholestasis.

BACKGROUND & AIMS: Intrahepatic cholestasis of pregnancy is a high-risk liver disease given the eventual deleterious consequences that may occur in the foetus. It is accepted that the abnormal accumulation of hydrophobic bile acids in maternal serum are responsible for the disease development. Hydrophobic bile acids induce oxidative stress and apoptosis leading to the damage of the hepatic parenchyma and eventually extrahepatic tissues. As coenzyme Q (CoQ) is considered an early marker of oxidative stress in this study, we sought to assess CoQ levels, bile acid profile and oxidative stress status in intrahepatic cholestasis. METHODS: CoQ, vitamin E and malondialdehyde were measured in plasma and/or tissues by HPLC-UV method whereas serum bile acids by capillary electrophoresis in rats with ethinyl estradiol-induced cholestasis and women with pregnancy cholestasis. RESULTS: CoQ and vitamin E plasma levels were diminished in both rats and women with intrahepatic cholestasis. Furthermore, reduced CoQ was also found in muscle and brain of cholestatic rats but no changes were observed in heart or liver. In addition, a positive correlation between CoQ and ursodeoxycholic/lithocholic acid ratio was found in intrahepatic cholestasis suggesting that increased plasma lithocholic acid may be intimately related to CoQ depletion in blood and tissues. CONCLUSION: Significant CoQ and vitamin E depletion occur in both animals and humans with intrahepatic cholestasis likely as the result of increased hydrophobic bile acids known to produce significant oxidative stress. Present findings further suggest that antioxidant supplementation complementary to traditional treatment may improve cholestasis outcome.

Role for enhanced faecal excretion of bile acid in hydroxysteroid sulfotransferase-mediated protection against lithocholic acid-induced liver toxicity.

The efficient clearance of toxic bile acids such as lithocholic acid (LCA) requires drug-metabolizing enzymes. We therefore assessed the influence of pregnenolone 16alpha-carbonitrile (PCN) treatment on LCA-induced hepatotoxicity and disposition of LCA metabolites using female farnesoid X receptor (FXR)-null and wild-type mice. Marked decreases in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, and hepatic tauroLCA (TLCA) concentrations were found in LCA-fed wild-type mice co-treated with PCN. Whereas induction of Cyp3a and hydroxysteroid sulfotransferase (Sult2a) proteins was observed in FXR-null and wild-type mice, clear increases in biliary 3alpha-sulfated TLCA but not total 6alpha-hydroxy LCA (taurohyodeoxycholic acid and hyodeoxycholic acid) were only observed in PCN-treated wild-type mice. Biliary 3alpha-sulfated TLCA output rate was increased 7.2-fold, but accounts for only 4.2% of total bile acid output rate in LCA and PCN-co-treated wild-type mice. Total 3alpha-sulfated LCA (LCA and TLCA) was, however, the most abundant bile acid component in faeces suggesting that efficient faecal excretion of biliary 3alpha-sulfated TLCA through escape from enterohepatic circulation. FXR-null mice, which have constitutively high levels of the Sult2a protein, were fed a diet supplemented with 1% LCA and 0.4% dehydroepiandrosterone (DHEA), a typical Sult2a substrate/inhibitor. The faecal total 3alpha-sulfated bile acid excretion was reduced to 62% of FXR-null mice fed only the LCA diet. Hepatic TLCA concentration and serum AST activity were significantly higher in FXR-null mice fed DHEA and LCA diet than in FXR-null mice fed the LCA diet or DHEA diet. These results suggest that hepatic formation of 3alpha-sulfated TLCA is a crucial factor for protection against LCA-induced hepatotoxicity.

Bile acid metabolism by colonic bacteria in continuous culture: effects of starch and pH.

Secondary bile acids (BA) have been shown to be involved as a promoting agent in the adenoma-carcinoma sequence of colorectal cancer. In previous studies, fermentation of starch has been shown to inhibit the degradation of primary to secondary BA by the colonic microflora. This study was designed to investigate BA metabolism in continuous cultures of mixed fecal bacteria to get further insights into the mechanisms of this inhibition. Fermentation vessels were fed with media containing cholic (0.6 g/l) and chenodeoxycholic acid (0.4 g/l). Cultures were either starch-free or enriched with starch (10 g/l). pH was controlled and adjusted to 7.0 or 6.0. Total culture duration was 28 days and concentrations of BA, short-chain fatty acids (SCFA), and starch were measured periodically. At pH 6, significantly more primary BA remained in the media and less secondary BA were produced. Total BA concentrations were lower at pH7. SCFA concentrations were higher in the vessels supplemented with starch. Starch was completely fermented and not present in significant amounts in any fermentation vial after the first week. These data indicate that bacterial breakdown of primary to secondary BA is inhibited when starch is simultaneously fermented. This effect can be explained by the reduction of pH resulting from SCFA production. Considering these findings, resistant starch which escapes assimilation in the small bowel may be a protective factor against colorectal cancer.

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, phosphates (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.

Bile acid excretion and cholesterol 7 alpha-hydroxylase expression in hypercholesterolemia-resistant rabbits.

We have developed a partially inbred substrain of New Zealand white rabbits (CRT/mlo) that are resistant to the hypercholesterolemia that accompanies cholesterol feeding to normal rabbits. The plasma cholesterol concentration of normal rabbits increases dramatically from about 30 mg/dl to > 300 mg/dl after they are fed a 0.1% cholesterol-enriched diet for 3-4 months. Cholesterol-fed CRT/mlo animals, however, maintain a cholesterol level of about 30 mg/dl during the entire cholesterol feeding period. In addition to the low plasma cholesterol level, measurements of cellular cholesterol indicate that the hepatic cholesterol content of the cholesterol-fed resistant rabbit remains markedly lower than it does in normal animals fed the same diet. The only mechanism for removal of significant quantities of cholesterol carbon from the body is via the fecal excretion of cholesterol, neutral sterol metabolites, and bile acids. In comparison to the basal, low-cholesterol diet, we observed that cholesterol-fed resistant rabbits had increased excretion of lithocholic acid, while excretion of this bile acid by cholesterol-fed normal rabbit remained similar to basal diet levels. Deoxycholic acid excretion, the other main bile acid excreted in the feces of rabbits, was decreased in response to cholesterol challenge in animals with either resistant or normal phenotypes, but the decrease was significantly less in the resistant rabbits. Thus, the resistant rabbits excreted relatively more lithocholic and deoxycholic acid than did the cholesterol-fed normal rabbit. The difference in bile acid excretion was also manifest by a higher than normal level of cholesterol 7 alpha-hydroxylase activity and cholesterol 7 alpha-hydroxylase mRNA in the livers from resistant versus normal rabbits. As cholesterol 7 alpha-hydroxylase is the putative rate-limiting step of bile acid synthesis, we believe that the increased excretion of bile acids by resistant animals is due, at least in part, to increased levels of cholesterol 7 alpha-hydroxylase expression.

Effects of oat and rye fractions on biliary and faecal bile acid profiles in Syrian golden hamsters (Mesocricetus auratus).

The effects of bran and starchy endosperm fractions of oat and rye on faecal weight and on biliary and faecal bile acids were studied in Syrian golden hamsters (Mesocricetus auratus). The animals fed on diets supplemented with steam-flaked oat bran, oat bran or rye bran had higher wet and dry weights of faeces compared with the animals fed on the fibre-free or low-fibre endosperm diets. A higher mean percentage of biliary cholic acid and a lower mean percentage of chenodeoxycholic and lithocholic (LCA) acids was observed in the bran-supplemented dietary groups. Animals fed on the bran-supplemented diets had increased daily faecal excretion of both total saponifiable and total free bile acids compared with the animals fed on fibre-free or endosperm-supplemented diets. The mean percentage of total saponifiable bile acids in the faeces was higher, and that of free bile acids lower in the animals fed on bran-supplemented diets. A significantly lower concentration of faecal free LCA was observed in the animals fed on the rye-bran diet. Both bran and endosperm diets reduced the faecal LCA:deoxycholic acid compared with the fibre-free diet, but the bran diets had a more pronounced effect than endosperm diets.

Effect of taurine on total parenteral nutrition-associated cholestasis.

A decrease in the formation/secretion of bile has been well documented in animals on total parenteral nutrition (TPN). Either an excess or an imbalance of amino acids (AA) has been most often implicated. In view of recent work showing that taurine promotes bile flow, bile acid secretion, and protects against hepatotoxic bile acids, the effect of adding taurine (15 mg/dL) to an AA solution was examined in guinea pigs on TPN for 3 days. The TPN-taurine group had a larger bile flow than the group without taurine and had bile acid secretory rates (BASR) similar to those of controls who were on saline by central catheter and had free access to food. Bile composition showed an increase in the secondary bile acid, 7-ketolithocholate and a concomitant decrease in chenodeoxycholate (CDC) in both experimental groups. Taurine led to a reversal of the usual predominance of glycine over taurine conjugated bile acids as well as to increases in HCO3 in cholesterol secretion. In response to a challenge with a large load of CDC, the TPN-taurine animals increased their BASR beyond those observed in the two other groups. These observations suggest that the addition of taurine to TPN solutions could play a role in the prevention of altered biliary function associated with AA solutions.

Bile acids and the increased risk of colorectal tumours after truncal vagotomy.

An association between colorectal cancer and previous peptic ulcer surgery is reported. In a prospective screening study, 100 asymptomatic patients (80 men and 20 women) who had undergone truncal vagotomy at least 10 years previously were investigated by barium enema, colonoscopy and gallbladder ultrasonography. Control data were obtained from forensic autopsy subjects. The incidence of neoplasms greater than or equal to 1.0 cm in the vagotomized group was 14 per cent (11 adenomas, 3 carcinomas) and 3 per cent in controls (P = 0.01). Duodenal bile obtained at endoscopy from 21 vagotomized patients with normal gallbladders and from 21 control patients undergoing endoscopy was analysed by high performance liquid chromatography. The mean percentage of cholic (CA), chenodeoxycholic (CDCA), deoxycholic (DCA) and lithocholic (LCA) acids in the bile of vagotomized patients was 32.3, 45.6, 20.7 and 1.4 per cent respectively compared with 45.3, 36.2, 17.9 and 0.7 per cent respectively in controls. The increased proportions of CDCA and LCA and decreased proportions of CA in the duodenal bile of vagotomized patients were significant (P less than 0.001; P = 0.02; P = 0.007). Abnormalities in bile acid metabolism may help to explain the increased risk of colorectal neoplasia 10 years after truncal vagotomy.

Effect of cholestyramine in early weaning on later response to serum and fecal steroid levels and cholesterol 7 alpha-hydroxylase activity to high-cholesterol diet in ExHC rats.

Male ExHC (exogenous hypercholesterolemic) rats were either prematurely weaned at 17 days of age or allowed to nurse until 35 days of age. The prematurely weaned rats were either fed a diet containing cholestyramine or cholestyramine-free diet until 35 days of age. Cholestyramine supplementation markedly increased fecal bile acid excretion and modified the composition. After giving a stock diet for 7 weeks, all rats received a cholesterol-enriched diet for 9 weeks. The serum cholesterol level in later time was not affected by early dietary manipulation. The activity of hepatic cholesterol 7 alpha-hydroxylase and fecal bile acid excretion at the end of the cholesterol challenge decreased in the cholestyramine-pretreated group, when compared to the normally weaned group. Fecal excretion and the ratio of the secondary (deoxycholic and lithocholic acids) to the primary (cholic and chenodeoxycholic acids) bile acids significantly decreased in the early cholestyramine-treated group. These results suggest that a modification of bile acid metabolism in early life may strongly influence the hepatic and possibly colonic bile acid metabolism in later life, when challenged with a high-cholesterol diet.

The effects of chenodiol on biliary lipids and their association with gallstone dissolution in the National Cooperative Gallstone Study (NCGS).

The National Cooperative Gallstone Study was a double-masked trial conducted to determine the efficacy and safety of chenodeoxycholic acid (chenodiol) for dissolution of cholesterol gallstones. Patients with radiolucent gallstones were randomly allocated to either a high dose (750 mg/d, n = 305) or low dose (375 mg/d, n = 306) of chenodiol or placebo (n = 305) administered for 2 yr. Specimens of gallbladder bile were obtained for biliary lipid analysis on 50% of all white obtained for biliary lipid analysis on 50% of all white patients at base line and after 3-mo therapy, on 45% at 12 mo, and on 36% at 24 mo. Among these specimens, 20% were inadequate for analysis. For analysis of data, available values during therapy were averaged up to time of dissolution, study exit, or study termination. In the high-dose group, percent chenodiol (molar percent of all bile acids) increased markedly and remained high during the 2 yr of follow-up. Also, molar percent cholesterol decreased significantly and remained low during the 2 yr of follow-up. In the low-dose group, percent chenodiol increased and remained significantly increased. Percent cholesterol saturation decreased at 3 mo, but at 24 mo it was not different from that in the placebo group, suggesting a physiological adaptation to the low dose by 2 yr. 79% of patients on high dose had greater than 70% chenodiol. Among these, half showed unsaturated bile (less than 100% cholesterol saturation) while the remainder were supersaturated; in the former group with unsaturated bile, 23% had complete dissolution and 51% had partial (greater than 50% reduction in stone size) or complete dissolution. In contrast, those with over 70% chenodiol and supersaturated bile had only 5% complete dissolution. Thus, development of unsaturated bile was a major factor associated with gallstone dissolution. The data also indicate that values for percent cholesterol saturation were a better predictor of gallstone dissolution than molar percent chenodiol, although a high percent chenodiol usually was required to obtain unsaturation.