PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “CHOLIC ACID”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources

Fecal excretion pattern of bile acids in rats fed high fat diets and neomycin in induced colon tumorigenesis.

Neomycin augments colon tumorigenesis in 1,2 - dimethylhydrazine treated rats fed polyunsaturated fat diet and decreases fecal cholic acid excretion, while it inhibits tumorigenesis with increased cholic acid and decreased deoxycholic acid excretions in rats fed high cholesterol diet. Participation of other fecal bile acids seems to be insignificant in relation to colon carcinogenesis.

1,2-Dimethylhydrazine↗

Inverse relationship between total glutathione S-transferase content and bile acid release in isolated hepatocytes from untreated, phenobarbital pretreated and hypothyroid rats.

The role of cytosolic anion binding proteins (glutathione S-transferases) in the hepatic transport of bile acids remains controversial. To investigate whether increased levels of the hepatocyte total glutathione S-transferase content were associated with changes in the release of bile acids from the hepatocyte, we measured the rate of release of radioactive bile acids in isolated hepatocytes from thyroidectomized, phenobarbital pretreated and untreated rats. The isolated hepatocytes were preincubated with either 14C-cholic acid or 14C-taurocholic acid, and the release rate of radiolabeled bile acids was determined. Hepatocyte total glutathione S-transferase content was measured by rocket immunoelectrophoresis. The release rate of the radiolabeled bile acids was significantly (P less than 0.005) decreased in both hypothyroid and phenobarbital pretreated hepatocytes. The levels of total glutathione S-transferase content were significantly (P less than 0.001) increased in the hepatocytes from both hypothyroid and phenobarbital pretreated animals. Our findings reveal a striking inverse relationship between the total glutathione S-transferase content of the hepatocyte and the release rate of radiolabeled bile acids in isolated hepatocytes from two independent animal models. These observations support the hypothesis that cytosolic anion binding proteins (glutathione S-transferases) may influence the net flux across the hepatocyte plasma membrane largely by limiting efflux.

Animals↗

Studies on the link between HMG-CoA reductase and cholesterol 7 alpha-hydroxylase in lymph-fistula rats: evidence for both transcriptional and post-transcriptional mechanisms for down-regulation of the two enzymes by bile acids.

The mechanism of down-regulation of hepatic HMG-CoA reductase and cholesterol 7 alpha-hydroxylase by cholic acid (CA) and chenodeoxycholic acid (CDCA) was investigated in rats with a lymph fistula. In accordance with the contention that bile acids are able to down-regulate HMG-CoA reductase by a mechanism independent of their effect on cholesterol absorption, inclusion of the above bile acids in diet (1%, wt/wt) reduced the HMG-CoA reductase specific activity by about 80%. The levels of mRNA were reduced by about 50% and the transcription rate (nuclear run-on) by 27% and 35%, respectively. Thus, HMG-CoA reductase appears to be regulated at both a transcriptional and a post-transcriptional level by bile acids. The cholesterol 7 alpha-hydroxylase activity as well as the corresponding mRNA levels were both reduced by about 50% by the same treatments. The transcription rate of the cholesterol 7 alpha-hydroxylase was not significantly affected by the treatment with CDCA, whereas the CA treatment reduced the transcription rate by about 24%. It is evident that bile acids regulate these two enzymes by different mechanisms in this model, in spite of the fact that the levels of mRNA were affected to about the same degree. The most obvious difference was the marked suppression of HMG-CoA reductase activity by cholic acid with relatively modest effects on transcription rate and level of mRNA. The latter finding is interesting in view of recent reports that dietary cholesterol also seems to down-regulate HMG-CoA reductase predominantly by a post-transcriptional mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Characterization of rat liver bile acid acyl glucuronosyltransferase.

Recent studies have suggested that bile acid acyl glucuronides form covalently bound protein adducts which may cause hypersensitivity reactions and increased morbidity in patients. Although the preferential biosynthesis of the acyl glucuronides has been known, the characterization of hepatic bile acid acyl glucuronosyltransferase has not yet been clearly elucidated. We have investigated the substrate specificity of the hepatic bile acid acyl glucuronosyltransferase using five common bile acids as substrates. The glucuronidation rate was dependent on the number of the hydroxy group on the steroid nucleus and mono-hydroxylated lithocholic acid, the more lipophilic common bile acid, was most effectively metabolized into its acyl glucuronide. The tri-hydroxylated cholic acid, the more water-soluble common bile acid, barely transformed into its glucuronide. Results showed decreasing of the initial velocity of the acyl glucuronidation with increasing of the concentration of substrate, lithocholic acid, owing to the substrate inhibition of the hepatic bile acid acyl glucuronosyltransferase. The substrate analogues, glycine and taurine conjugated bile acids, which exist in the body fluids in high concentrations, also inhibited the enzyme's activity. In addition, enzymatic reaction products, bile acid acyl glucuronides, also inhibited the activity. These inhibitory mechanisms may be responsible for the low concentration of bile acid acyl glucuronides in urine and may be an important detoxification system in the body.

Animals↗

Oligomeric cholates: amphiphilic foldamers with nanometer-sized hydrophilic cavities.

The hydroxyl at the C-3 of cholic acid was converted to an amino group, and the resulting amino-functionalized cholic acid was used as a monomer to prepare amide-linked oligomeric cholates. These cholate oligomers fold into helical structures with nanometer-sized hydrophilic internal cavities in solvent mixtures consisting of mostly nonpolar solvents such as carbon tetrachloride or ethyl acetate/hexane and 2-5% of a polar solvent such as methanol or DMSO. The conformations of the foldamers were studied by UV, fluorescence, fluorescence quenching, and fluorescence resonance energy transfer. The nature of the polar/nonpolar solvents and their miscibility strongly influenced the folding reaction. Folding was cooperative, as evidenced by the sigmoidal curves in solvent denaturation experiments. The folded conformers became more stable with an increase in the chain length. The folding/unfolding equilibrium was highly sensitive toward the amount of polar solvent. One percent variation in the solvent composition could change the folding free energies by 0.5-1.4 kcal/mol.

Amides↗

Dietary fish oil enhances monocyte adhesion and fatty streak formation in the hypercholesterolemic rat.

Using the rat model of atherosclerosis, the influence of dietary fish oil on early stages of atherosclerotic lesion formation was studied. Normocholesterolemic rats (serum cholesterol less than 100 mg/dl), moderately hypercholesterolemic rats fed cholesterol and cholic acid (serum cholesterol less than 400 mg/dl), and severely hypercholesterolemic rats fed cholesterol, cholic acid, and 2-thiouracil (serum cholesterol greater than 900 mg/dl) had their diets supplemented with 5% (w/w) "MaxEPA" fish oil for a period of 2 weeks. In each diet group safflower oil was used as a control for fish oil. Monocyte adhesion to the thoracic aorta and intimal foam cell formation were used to measure the extent of atherosclerotic lesion formation in each rat. Cholesterol and triglyceride levels were measured in both plasma and lipoprotein fractions. In normocholesterolemic rats, fish oil did not influence the morphology of the vessel wall. In moderately hypercholesterolemic rats, monocyte adhesion was the same irrespective of dietary oil, however, intimal foam cell formation was 2-fold higher in the fish oil-fed animals despite a reduction in serum cholesterol levels when compared to the safflower oil-fed animals. In severely hypercholesterolemic rats, monocyte adhesion to the vessel wall and intimal foam cell formation were both 4-fold higher in the fish oil compared with the safflower oil fed animals. These observations could not be attributed to differences in the plasma or lipoprotein profiles of safflower oil vs. fish oil fed rats. The results of this study suggest that dietary fish oil, when fed to hypercholesterolemic rats for a period of 2 weeks, enhances the rate of monocyte adhesion and fatty streak formation in the thoracic aorta.

Animals↗

Effect of sesame oil on serum and liver lipid profiles in the rat.

In our previous study (Satchithanandam, S., Reicks, M., Calvert, R.J., Cassidy, M.M. and Kritchevsky, D. (1993) J. Nutr. 123, 1852-1858), we found that the absorption of lymphatic cholesterol by rats fed diets containing 24% sesame oil was about 50% less than that by rats fed the control diet containing no sesame oil. The effect of sesame oil on serum cholesterol levels was not determined at that time. In the present study, three groups of male Wistar rats (75-100 g) were fed a control diet or a diet containing 12 or 24% sesame oil. To increase serum cholesterol levels, 1% cholesterol and 0.5% cholic acid were added to each diet. After rats were fed for 4 weeks, total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglyceride levels were measured in the serum. Liver weight and cholesterol and triglyceride levels were determined. Liver cholesterol levels were significantly lower in rats fed the 24% sesame oil diet, and the liver lipid level was significantly higher in the 24% sesame oil-fed group, compared with levels in the group fed the control diet. Liver weights and esterified cholesterol and liver triglyceride levels were not significantly different among the groups. Levels of serum total cholesterol and LDL-cholesterol were significantly lower in rats fed the 24% sesame oil diet, compared with levels in the control group. Serum triglyceride and HDL-cholesterol levels did not differ significantly among the groups. The mechanism by which a diet containing 24% sesame oil reduces levels of serum and liver cholesterol, liver LDL cholesterol, and liver lipids is not known. However, the high degree of unsaturation (85%) of sesame oil and the presence of linoleic acid may be important factors.

Animals↗

Effects of lovastatin and dietary cholesterol on bile acid kinetics and bile lipid composition in healthy male subjects.

We measured bile acid kinetics and bile lipids in 12 human subjects on a metabolic ward in four randomly allocated, 6-7 week periods: 1) lovastatin (40 mg b.i.d) + low cholesterol diet (mean 246 mg/day); 2) lovastatin+high cholesterol diet (mean 1071 mg/day); 3) low cholesterol diet alone; and 4) high cholesterol diet alone. Lovastatin did not significantly alter fractional turnover, synthesis, absorption, enterohepatic cycling, or pool sizes of bile acid measured by the Lindstedt method. The high cholesterol diet increased fractional turnover and synthesis rate of cholic acid, but not chenodeoxycholic acid, without altering pool size of either bile acid. The high cholesterol diet decreased bile acid absorption, but only during lovastatin treatment, suggesting the possibility of a "cholestyramine-like" effect of dietary cholesterol, appreciable at least when biliary cholesterol secretion is reduced by lovastatin. As in previous studies, lovastatin markedly lowered saturation index of gallbladder bile. Increased cholesterol consumption did not significantly alter cholesterol saturation index, suggesting that dietary cholesterol may not be a major factor in cholesterol gallstone pathogenesis.

Absorption↗

Capillary gas-liquid chromatography of 6-hydroxylated bile acids.

Gas-liquid chromatographic separation of several bile acids with a hydroxyl group at C-6 is described on two capillary columns, CP-Sil-19 CB and CP-Sil-5 CB. The gas-liquid chromatographic retention indices of bile acids with 6 alpha- and 6 beta-hydroxyl groups are compared with those of bile acids without the C-6 hydroxyl group and the effect of the C-6 hydroxyl group on the retention indices of bile acids is determined. Both 6 alpha- and 6 beta-hydroxyl groups increase the retention index of a bile acid. The retention indices of 6 alpha- or 6 beta-hydroxyl derivatives of chenodeoxycholic acid were found to be higher than those of the corresponding 6-hydroxy derivatives of cholic acid on the CP-Sil-19 CB column but lower on the CP-Sil-5 CB column. Although all 6-hydroxylated derivatives of lithocholic, chenodeoxycholic and cholic acids were not completely resolved on either column alone, combining the two columns resulted in the complete separation of all these compounds.

Bile Acids and Salts↗

The effect of polyunsaturated fats on bile acid metabolism and cholelithiasis in squirrel monkeys.

Squirrel monkeys (Saimiri sciureus) were fed diets containing safflower oil, butter, or coconut oil and 1 mg cholesterol/cal for 15--17 mo to examine the effect of type of fat on cholelithiasis and bile acid metabolism. Controls were fed low cholesterol diets containing an isocaloric mixture of the three fats. Cholic acid fractional catabolic rate, pool size, chenodeoxycholic acid pool size, and total bile acid pool size and excretion rate were estimated using a modification of Lindstedt's isotopic turnover procedure. The animals fed the safflower oil diet had the highest incidence of cholelithiasis (9/10) when compared to those fed butter (3/7) and coconut oil (1/7). Animals consuming the low cholesterol control diet did not develop gallstones. The butter- and coconut oil-fed groups had significantly (p less than 0.05) expanded bile acid pools when compared to controls, and the butter-fed group had a significantly increased (p less than 0.05) cholic acid fractional catabolic rate. The safflower oil group had the smallest mean bile acid pool and the highest mean lithogenic index of the cholesterol-fed groups. It was concluded that the safflower oil-fed animals had a higher incidence of cholelithiasis than the butter group because, unlike the latter group, they did not compensate for a high cholesterol intake by stimulating bile acid synthesis. The animals consuming coconut oil apparently did not absorb cholesterol to the extent of the other groups and as a result their bile did not become saturated with cholesterol.

Animals↗

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.

Adult↗

Role of bile in intestinal barrier function and its inhibitory effect on bacterial translocation in obstructive jaundice in rats.

BACKGROUND: Our previous study using genetically labeled Escherichia coli strain JNW14 revealed that obstructive jaundice promotes bacterial translocation in rats and that the absence of bile in the intestinal tract is considered to be a factor inducing bacterial translocation. The aim of this study was to investigate the role of bile and bile acids in intestinal barrier function against bacterial translocation. MATERIALS AND METHODS: Eight-week-old male specific-pathogen-free Wistar rats were subjected to ligation of their common bile ducts (CBDL). The CBDL rats were treated with bacitracin, neomycin sulfate, and streptomycin sulfate, and the intestinal tract was colonized with E. coli strain JNW14, which was genetically labeled with resistant markers against the above three antibiotics, to monitor the bacterial translocation. The rats were then administered saline, cholic acid (20 mg/100 g BW), taurocholic acid (TCA: 5-50 mg/100 BW), or bile (1.5-6 mL/day) via a duodenal catheter. The degree of bacterial translocation of E. coli strain JNW14 to the mesenteric lymph nodes was compared. Histopathological examination of the terminal ileum and intestinal permeability test using phenolsulfonphthalein was also performed. RESULTS: Both cholic acid and TCA showed no inhibitory effect on bacterial translocation at any of the doses tested in CBDL rats, although TCA significantly decreased the numbers of E. coli strain JNW14 in the cecum. However, bile administration reduced the numbers of E. coli strain JNW14 in the cecum and mesenteric lymph nodes in CBDL rats although the inhibitory effect was weak. The integrity and permeability of the intestinal mucosa were kept at normal levels by bile administration in CBDL rats whereas the morphological changes, such as villous atrophy, villous edema, and lacteal canal dilatation, were observed in other CBDL rats. CONCLUSION: Bile plays an important role in maintaining the intestinal barrier function to prevent the invasion of enteric bacteria to the underlying tissues, suggesting that the intestinal administration of bile to patients with obstructive jaundice is a useful way to reduce infectious complications by inhibiting bacterial translocation from the intestine to other organs.

Animals↗

Multiple copies of a bile acid-inducible gene in Eubacterium sp. strain VPI 12708.

Eubacterium sp. strain VPI 12708 is an anaerobic intestinal bacterium which possesses inducible bile acid 7-dehydroxylation activity. Several new polypeptides are produced in this strain following induction with cholic acid. Genes coding for two copies of a bile acid-inducible 27,000-dalton polypeptide (baiA1 and baiA2) have been previously cloned and sequenced. We now report on a gene coding for a third copy of this 27,000-dalton polypeptide (baiA3). The baiA3 gene has been cloned in lambda DASH on an 11.2-kilobase DNA fragment from a partial Sau3A digest of the Eubacterium DNA. DNA sequence analysis of the baiA3 gene revealed 100% homology with the baiA1 gene within the coding region of the 27,000-dalton polypeptides. The baiA2 gene shares 81% sequence identity with the other two genes at the nucleotide level. The flanking nucleotide sequences associated with the baiA1 and baiA3 genes are identical for 930 bases in the 5' direction from the initiation codon and for at least 325 bases in the 3' direction from the stop codon, including the putative promoter regions for the genes. An additional open reading frame (occupying from 621 to 648 bases, depending on the correct start codon) was found in the identical 5' regions associated with the baiA1 and baiA3 clones. The 5' sequence 930 bases upstream from the baiA1 and baiA3 genes was totally divergent. The baiA2 gene, which is part of a large bile acid-inducible operon, showed no homology with the other two genes either in the 5' or 3' direction from the polypeptide coding region, except for a 15-base-pair presumed ribosome-binding site in the 5' region. These studies strongly suggest that a gene duplication (baiA1 and baiA3) has occurred and is stably maintained in this bacterium.

Amino Acid Sequence↗

Studies on adsorption characteristics of bile acids and methotrexate to a new type of anion-exchange resin, colestimide.

The adsorption characteristics of various bile acids and methotrexate to a new type of anion-exchange resin, colestimide, were studied in vitro and compared with those to cholestyramine. For bile acids, colestimide was shown to have a higher capacity than cholestyramine. For example, approximately 1.4-fold higher for cholic acid and 2.0-fold for deoxycholic acid in water. In the presence of physiological anions, the degree of adsorption of cholic acid to both resins was greatly reduced, whereas adsorption of deoxycholic acid was only slightly reduced. Furthermore, the bed-volume of colestimide swelled about 6.8-fold in water, hence the anion-exchange groups of this resin are expected to be able to function effectively in adsorption of bile acids in the gut. In addition, colestimide was found to have high adsorption capacity for methotrexate, not only in water but also in media containing various physiological anions, and thus it is suggested that colestimide is a potential oral antidote to reduce possible toxicity by methotrexate through interruption of enterohepatic circulation.

Anion Exchange Resins↗

Polydeoxycholate in human and hamster feces: a major product of cholate metabolism.

Fecal bile acid excretion is one of the two major routes by which cholesterol is eliminated from the body, fecal cholesterol being the other. During their enterohepatic circulation, bile acids are secreted into the duodenum, pass down the jejunum and into the ileum where more than 95% is reabsorbed by the gut. Bile acids that escape reabsorption in the small intestine are metabolized by microorganisms in the large intestine. The major routes of metabolism are reported to be deconjugation, dehydroxylation, especially at the 7 alpha-hydroxy position, and dehydrogenation of the hydroxyl moieties. There are also some reports that saponifiable metabolites containing mostly deoxycholic acid form a major component of the bile acids found in human feces. We have identified a novel metabolite of cholic acid, 3 alpha-hydroxy polydeoxycholate, in both human and hamster feces that is the major constituent of these saponifiable metabolites. Furthermore, we have shown in hamsters that the animals that excreted more bile acid were excreting the additional bile acid as polydeoxycholate. As expected, there was a negative correlation between bile acid excretion in the feces and plasma cholesterol concentrations in these animals. We speculate that polydeoxycholate is formed in the lower gut of both humans and hamsters and that, by its formation, bile acid will be sequestered in an insoluble form, thus inhibiting its reabsorption by the gut. This process may help to reduce plasma cholesterol concentrations and coronary heart disease in humans.

Animals↗

Suppression of anti-Candida activity of murine and human neutrophils by glucocorticoids.

Effects of glucocorticoid (GC) compounds on inhibitory activity of neutrophils to mycelial growth of Candida albicans were examined by in vitro crystal violet staining method with 14 hr coculture. Both GC hormones (hydrocortisone > or = 6 x 10(-7) M and corticosterone > or = 10(-6)M) and anti-inflammatory GC agents (prednisolone > or = 10(-7) M and dexamethasone > or = 10(-8) M) significantly suppressed anti-Candida activity of murine casein-induced neutrophils. Anti-Candida activity of human neutrophils prepared from peripheral blood was also suppressed by hydrocortisone (> or = 6 x 10(-7) M). These GC compounds did not affect the Candida growth in the absence of neutrophils. Steroidal compounds without anti-inflammatory activity, cholesterol, cholic acid, aldosterone did not suppress neutrophil activity. These results suggest that GCs at their physiological or clinical concentration may suppress anti-Candida activity of neutrophils in vivo.

Aldosterone↗

Excretion of cholate glucuronide.

[3-3H]Cholic acid glucuronide [7 alpha,12 alpha-dihydroxy-3 alpha-O-(beta-D-glucopyranosyluronate)-5 beta- cholan-24-oate] was synthesized and administered to rats prepared with either an external biliary fistula or a ligated bile duct. When bile fistula animals were given either microgram or milligram amounts of the glucuronide, biliary secretion of label was rapid and efficient: greater than 90% of the administered label was secreted within 60 min and total recovery of label in bile was 98.6 +/- 1.2%. Studies in which [14C]taurocholate was included in the dose indicated that this bile acid was secreted into bile significantly more rapidly than was the glucuronide. In animals with ligated bile ducts, urinary excretion was the major route of elimination: after 20 hr, 83.4 +/- 9.3% of the administered dose had been excreted in urine. Urinary excretion of cholate glucuronide was significantly more rapid than that of taurocholate. Gas-liquid chromatographic analysis of the methyl ester acetate derivatives of labeled compounds isolated from bile and urine by chromatography established that the bulk (greater than 70%) of the administered material was secreted in bile or excreted in urine as the intact cholate glucuronide. From these results, we conclude that the glucuronidation of cholic acid produces a derivative which is rapidly and effectively cleared from the circulation and excreted.

Animals↗

A comparison of the lipid-lowering and intestinal morphological effects of cholestyramine, chitosan, and oat gum in rats.

Cholestyramine, chitosan, and oat gum are lipid-lowering compounds. Cholestyramine use in humans may contribute to colonic adenocarcinoma; chitosan and oat gum are being studied in the rat to determine their potential for human use. To compare these compounds, we fed three groups of 10 male Sprague-Dawley rats one of the substances at 5% of diet with 1% cholesterol and 0.2% cholic acid; two other groups were fed cellulose with and without 1% cholesterol and 0.2% cholic acid. All groups had similar food intake and weight gains. Cholesterol feeding increased total liver lipids almost 3-fold and liver cholesterol concentration almost 10-fold. Cholestyramine, oat gum, and chitosan all significantly lowered liver cholesterol with cholestyramine feeding yielding levels identical to the noncholesterol-fed basal group. Chitosan and oat gum lowered liver cholesterol moderately. Cholestyramine and chitosan both significantly lowered serum cholesterol compared to the cellulose group. Oat gum was less effective. Hemoglobin and serum iron were similar in all groups except the oat gum group, which had decreased serum iron. Histological examination of small and large bowel with morphometry revealed statistically significant increases in both proximal and distal small bowel and distal large bowel mucosal thickness in the cholestyramine-fed group. No changes were noted in the proximal large bowel. Neither chitosan nor oat gum produced mucosal change other than an increase in the distal small bowel with the oat gum diet. Chitosan may have lipid-lowering effects similar to those of cholestyramine without the deleterious changes in intestinal mucosa.

Animals↗