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PubMed2002

The crystallization of calcium carbonate on sodium cholate.

Recent studies in the bibliography showed that calcium carbonate was the major constituent (77.8%) in gall stones, and the polymorph calcite was at 62.5% of the cases examined. The kinetics of crystallization of calcite on sodium cholate has been studied using the constant composition technique. Analysis of the initial rates as a function of the solution supersaturation, according to the classical nucleation theory, yielded a value of 33mJm(-2) for the surface energy of the growing phase and a five-ion cluster, forming the critical nucleus. The apparent order for the calcite crystallization was found to be 4.5+/-0.7 indicative of a surface nucleation mechanism. The formation of calcite may be initiated through the interaction of Ca2+ ions with the negative end of the C=0 bond of the sodium cholate molecule.

Journal Article↗
PubMed2003

Probing the binding dynamics to sodium cholate aggregates using naphthalene derivatives as guests.

The binding dynamics with bile salt aggregates for a series of naphthalene derivatives of different polarities was studied using fluorescence and laser flash photolysis. Fluorescence was employed to determine the nature of the binding site for each guest and the accessibility of the bound guest to quenchers. Laser flash photolysis was employed to study the mobility of the triplet states of the naphthalenes between the sodium cholate aggregates and the aqueous phase. Primary aggregates, which provide an environment protected from quenchers in the aqueous phase, bind 1- and 2-ethylnaphthalene as guests. The complexation dynamics with this type of aggregate is slow. 1- and 2-Naphthyl-1-ethanol, and 1- and 2-acetonaphthone bind to the secondary aggregates, which provide moderate protection from quenching and faster binding dynamics. The addition of salts lowered the cholate concentration at which primary aggregates were formed, but did not influence the formation of secondary aggregates.

Journal Article↗
PubMed1996

Effects of Ursodeoxycholate and cholate feeding on liver disease in FVB mice with a disrupted mdr2 P-glycoprotein gene.

BACKGROUND & AIMS: The mouse mdr2 gene encodes a P-glycoprotein expressed in the hepatocanalicular membrane. Inactivation of this gene causes lack of biliary phospholipid and cholesterol secretion and non-suppurative cholangitis. The aim of this study was to investigate the role of bile salt hydrophobicity in induction of liver pathology in mdr2 (-/-) mice. METHODS: Mice (+/+) wild type or (-/-) knockout for the mdr2 gene were fed with either purified control diet or this diet supplemented with cholate (0.1%) or ursodeoxycholate (0.5%) for 3, 6, or 22 weeks after weaning. Liver histology was semiquantitatively scored. RESULTS: Each mouse fed bile acid became the major constituent of the bile salt pool. The cholate diet during 22 weeks induced only very mild liver pathology in (+/+) mice. By contrast, lever histology had already deteriorated after 3 weeks in the (-/-) mice and caused pronounced inflammatory nonsuppurative cholangitis and fibrosis in the 75% of mice that survived. Dietary ursodeoxycholate had no effect on histology in (+/+) mice but improved liver pathology significantly in (-/-) mice compared with purified control diet; the decrease of ductular proliferation and portal inflammation was most prominent after 22 weeks. CONCLUSIONS: The cholangiolitis and its sequelae in the mdr2 knockout mice depend on bile salt hydrophobicity.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1995

ATP-dependent efflux of 2,4-dinitrophenyl-S-glutathione. Properties of two distinct transport systems in inside-out vesicles from L1210 cells and a variant subline with altered efflux of methotrexate and cholate.

The transport of 2,4-dinitrophenyl-S-glutathione (DNP-SG) into inside-out vesicles from L1210 cells was employed to identify and characterize ATP-dependent efflux routes for DNP-SG. Measurements of ATP-dependent uptake at varying concentrations of [3H]DNP-SG revealed the presence of two distinct transport systems. Transport at low substrate concentrations occurred predominantly via a high affinity system (Km = 0.63 microM), whereas a low affinity system (Km = 450 microM) predominated at high concentrations of substrate. The high affinity system was characterized by a potent inhibition by the glutathione conjugates of bromosulfophthalein (Ki = 0.09 microM) and ethacrynic acid (Ki = 0.44 microM), leukotriene C4 (Ki = 0.20 microM), and the taurate diconjugate of bilirubin (Ki = 0.10 microM). The low affinity transport system for DNP-SG exhibited a high affinity for bilirubin ditaurate (Ki = 1.8 microM), indoprofen (Ki = 3.0 microM), and biphenylacetic acid (Ki = 5.9 microM). Different results were obtained with an L1210/C7 variant which has a defect in the efflux of methotrexate and cholate. Vesicles from the latter cells contain the same low affinity transport activity as parental cells, but the high affinity route is absent and has been replaced by a system with an intermediate affinity for DNP-SG (Km = 4.5 microM). These results indicate that L1210 cells contain two unidirectional efflux pumps for DNP-SG with substantial differences in inhibitor sensitivity. The high affinity system shows a binding preference for glutathione conjugates but can also accommodate large anionic conjugates, whereas the low affinity system has a binding preference for large organic anions. Results with the variant cells support the hypothesis that the high affinity transport system for DNP-SG also mediates the unidirectional efflux of methotrexate and cholate in intact L1210 cells.

Adenosine Triphosphate↗
PubMed2000

The human liver-specific homolog of very long-chain acyl-CoA synthetase is cholate:CoA ligase.

Unconjugated bile acids must be activated to their CoA thioesters before conjugation to taurine or glycine can occur. A human homolog of very long-chain acyl-CoA synthetase, hVLCS-H2, has two requisite properties of a bile acid:CoA ligase, liver specificity and an endoplasmic reticulum subcellular localization. We investigated the ability of this enzyme to activate the primary bile acid, cholic acid, to its CoA derivative. When expressed in COS-1 cells, hVLCS-H2 exhibited cholate:CoA ligase (choloyl-CoA synthetase) activity with both non-isotopic and radioactive assays. Other long- and very long-chain acyl-CoA synthetases were incapable of activating cholate. Endogenous choloyl-CoA synthetase activity was also detected in liver-derived HepG2 cells but not in kidney-derived COS-1 cells. Our results are consistent with a role for hVLCS-H2 in the re-activation and re-conjugation of bile acids entering liver from the enterohepatic circulation rather than in de novo bile acid synthesis.

Amino Acid Sequence↗
PubMed1993

Spermicidal and antiviral properties of cholic acid: contraceptive efficacy of a new vaginal sponge (Protectaid) containing sodium cholate.

Cholic acid (sodium cholate) exhibits a strong spermicidal and antiviral [anti-human immunodeficiency virus (HIV)-1] activity. The same effects are observed for F-5 Gel, the active mixture of a new contraceptive sponge (Protectaid), which contains sodium cholate in association with low concentrations (0.5%) of nonoxynol-9 and benzalkonium chloride. Both cholic acid and the F-5 Gel exert a dose-dependent, in-vitro inhibitory effect (i) on the activity of HIV-1 associated reverse transcriptase in an acellular system and (ii) on the potential of HIV-1 efficiently to infect human lymphocytes. During 12 months use, the contraceptive efficacy of the 'Protectaid' sponge was 100% in 20 young women who had chosen this method for reasons of both contraception and anti-sexually transmitted disease. No side-effects were recorded throughout this period. Cervical cultures at 6-month intervals showed the presence of Mycoplasma hominis and Candida albicans in one or two cases. The combined spermicidal and anti-HIV properties of cholic acid reported in this paper and used in the 'Protectaid' sponge offer a new and modern protective method of contraception.

Adult↗
PubMed1979

Disintegration of Rhodospirillum rubrum chromatophore membrane into photoreaction units, reaction centers, and ubiquinone-10 protein with mixture of cholate and deoxycholate.

1. The membrane of Rhodospirillum rubrum chromatophores was disintegrated with mild detergents (cholate and deoxycholate) in order to study the spatial arrangement of the functional proteins in the photochemical apparatus and the electron transport system in the membrane. 2. The components solubilized from the membrane by a mixture of cholate and deoxycholate (C-DOC) were separated into four fractions by molecular-sieve chromatography in the presence of C-DOC; they were designated as F1, F2, F3, and F4 in the order of elution. The fractions were further purified by repeated molecular-sieve chromatography in the presence of C-DOC until each fraction was chromatographically homogeneous. 3. F1 appeared to be conjugated forms of F2. 4. The purified F2 was composed of a rigid complex having a weight of 7 X 10(5) daltons, containing approximately 10 different kinds of protein species with molecular weights of 3.8 X 10(4), 3.6 X 10(4), 3.5 X 10(4), 2.8 X 10(4), 2.7 X 10(4), 2.6 X 10(4), 1.3 X 10(4), 1.2 X 10(4), 1.1 X 10(4), and 1.0 X 10(4). The complex contained 33 bacteriochlorophylls, 4 iron atoms, and 90 phosphates, but no cytochrome, ubiquinone, or phospholipid. It showed the same reaction center activity as chromatophores, indicating that the complex was a unit of the photochemical apparatus (photoreaction unit). Each chromatophore of average size was estimated to possess about 24 photoreaction units. 5. The purified F3 showed an absorbance spectrum characteristic of reaction centers, and contained 3.4 bacteriochlorophylls, 2.0 bacteriopheophytins, and 1.9 acid-labile iron atoms, but no cytochrome or ubiquinone (C-DOC reaction center). It had a weight of 1.2 X 10(5) daltons, and the main components were 4 protein species with molecular weights of 2.8 X 10(4), 2.7 X 10(4), 2.6 X 10(4), and 1.0 X 10(4). 6. The purified F4 showed a molecular weight of about 11,000, and contained one mole of ubiquinone-10 per mole (ubiquinone-10 protein). 7. The reaction center activity of C-DOC reaction centers was stimulated by ubiquinone-10 protein. In addition, the reaction center oxidized reduced cytochrome c2 in the light, provided that ubiquinone-10 protein was present (photo-oxidase activity).

Bacterial Chromatophores↗
PubMed1983

Reconstitution of a functional beta-adrenergic receptor using cholate and a novel method for its functional assay.

Solubilization of purified turkey erythrocyte membranes at increasing cholate to protein ratios and in the presence of salt, extracts up to 20% of the beta-adrenergic receptor together with the GTP stimulatory protein (Ns) of adenylate cyclase. Upon removal of the cholate, by active absorption on Bio-beads, the functional interaction between the beta-receptor and the GTP regulatory protein Ns is quantitatively restored. The receptor (R) in the presence of l-isoproterenol and p[NH]ppG is able to catalyze the activation of Ns to its permanently active state, N's p[NH]ppG, with a rate constant (kon) identical to that of the native membrane. Reconstitution of the R/Ns mixture using poly(ethyleneglycol)-6000 restores the receptor binding properties as effectively as SM-2 Bio-beads. Unlike SM-2 Bio-beads, however, poly(ethyleneglycol) is not as efficient in restoring the R to Ns functional coupling. In this communication we also report on the ability to monitor quantitatively N's . p[NH]ppG, using native turkey erythrocyte membranes in the presence of Lubrol-PX as the source of the catalytic unit (c) of adenylate cyclase. The latter method is as efficient as using S49 AC- lymphoma cell membranes but much less expensive. Using this technique, we also demonstrate that when the Ns to C interaction is nullified, employing treatment with N-ethylmaleimide, the parameters which characterize R to Ns coupling remain unchanged.

Adenylyl Cyclases↗
PubMed1981

Differential timing of maximal postprandial concentrations of plasma chenodeoxycholate and cholate: its variability and implications.

The concentrations of conjugated chenodeoxycholate and cholate in serum have been measured in 26 controls and 19 patients with liver disease before and after taking a fat-containing meal. The times at which maximum bile salt concentrations occurred varied considerably between individuals. In the majority of cases maximal concentrations of the two bile salts occurred simultaneously but in 3 subjects maximal concentrations of chenodeoxycholate were found 15-60 min prior to maximal cholate concentrations. The measurement of bile salt concentration in a single sample taken 2 h after the fatty test meal would have produced two false-negative results in the patients with liver disease. It is concluded that the jejunal absorption of dihydroxylated bile salts may not be significant in the majority of individuals and that the protocol for assessment of liver function by postprandial bile salt analysis should include at least two blood samples collected at 1.5 and 2 h after ingestion of the test meal.

Chenodeoxycholic Acid↗
PubMed2001

Characterization, stability and in-vivo distribution of asialofetuin glycopeptide incorporating DSPC/CHOL liposomes prepared by mild cholate incubation.

In this study, a small triantennary asialoglycopeptide of fetuin (A-F2) was used as a ligand to direct liposomes to hepatocytes. A-F2 was cleaved from asialofetuin, purified, conjugated with fatty acids and incorporated into pre-formed sonicated DSPC/Chol (2:1) liposomes. A mild cholate incubation method for incorporating the A-F2 ligand on pre-formed vesicles was used. In preliminary in vivo experiments 111In3+ encapsulated in A-F2/palmityl liposomes was seen to accumulate in the liver of mice significantly faster than when encapsulated in non-ligand bearing liposomes of the same lipid composition (studied before), justifying further investigation of this system. The presence of the A-F2/fatty acid conjugate in a functional form on the vesicle surface was confirmed by their reversible agglutination in the presence of Ricinus communis agglutinin (RCA120). Effects of ligand incorporation on the vesicle size distribution, z-potential, membrane integrity and stability were monitored. The results demonstrate that highest ligand incorporation was achieved when liposomes and ligand were co-incubated in the presence of 1 mM sodium cholate. Incorporation increased with the length of the fatty acid used for A-F2 conjugation. Ligand-bearing liposomes were demonstrated to be smaller in diameter (about 30%) with a more positive z-potential in comparison to control vesicles while ligand incorporation did not influence the liposome membrane integrity. The size of the ligand-incorporating vesicles was maintained after 24 hours of incubation in isotonic buffer, proving that the vesicles do not aggregate. Although the preliminary biodistribution results may suggest that ligand bearing liposomes are accumulating in the liver, further cell culture, in vivo distribution and especially liver fractionation studies are required in order to clarify the intrahepatic localization of these liposomes and the ability to target liver hepatocytes in vivo.

Animals↗
PubMed1990

Sodium cholate-induced changes in the conformation and activity of rat pancreatic cholesterol esterase.

Pancreatic cholesterol esterase (CEase) regulates dietary cholesterol absorption and is activated in the presence of trihydroxy bile salts while remaining inactive monohydroxy bile salts. CEase from rat pancreas has been purified by ammonium sulfate precipitation, hydroxylapatite chromatography, and gel filtration on Sephacryl S-200/S-300 columns connected in series, and its homogeneity and Mr (55,418 +/- 288) have been determined by sedimentation equilibrium centrifugation. The effects of tri-, di-, and monohydroxy bile salts on the conformation of the purified enzyme in buffer solution and in an in vitro assay system were studied by circular dichroism spectropolarimetry. The CD spectrum of the enzyme in solution shows a curve shape suggestive of an alpha-helicity, but low mean residue ellipticity (MRE) values may indicate an important beta-turn contribution. Sodium cholate, a trihydroxy bile salt, induces a decrease in the negative MRE values of the enzyme in solution at bile salt concentrations of 70-100 nM, with no further spectral changes at concentrations as high as 1 mM. Sodium cholate concentrations higher than 1 microM also induce an increase in the enzyme's negative MRE values under activity assay conditions, which reverts toward its original value once the reaction reaches equilibrium. These latter changes are interpreted as induced by substrate binding to the enzyme followed by partial substrate depletion after the reaction reaches equilibrium. Sodium deoxycholate, a dihydroxy bile salt, induces unstable transient increases and decreases in the MRE values of CEase in buffer solution and under activity assay conditions. These changes are bile salt concentration-dependent and may reflect self-association of the protein. Sodium taurolithocholate, a monohydroxy bile salt, does not affect the CD spectrum of CEase, and neither the di- or the monohydroxy bile salt activates the enzyme.

Animals↗
PubMed1989

[Cholate-forming function of the liver in patients with chronic alcoholism].

The level of bile acids was studied in the bile and feces in 119 patients with chronic alcoholism using thin-layer chromatography. The cholate-forming function of the liver was found to increase in patients with short alcohol anamnesis in chronic alcoholism. With advance of the alcohol anamnesis the number of patients with reduced cholate-forming function of the liver increased.

Alcoholism↗
PubMed1985

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↗
PubMed1976

Diamagnetic levitation in the fractionally superconducting bile cholates.

Diamagnetic levitation similar to that seen in metallic superconductors has been observed in organic compounds; namely, the bile cholates. Levitation phenomena, with forces exceeding 400 lbs/in, occurred in repeated experiments at transition temperatures extablished by susceptibility and resistivity measurements. With crystalline phase change ruled out by X-ray diffraction studies, the observed levitation must be regarded as due to superconductive effects occurring in small domains randomly dispersed throughout the insulating bulk of the investigated cholates. The transition temperatures observed in some of these compounds were higher than those seen in the metals.

Cholic Acids↗
PubMed2004

Effects of blockers of Ca2+ channels and other ion channels on in vitro excystment of Paragonimus ohirai metacercariae induced by sodium cholate.

The inhibitory effects of various ion channel blockers were examined on in vitro excystment of Paragonimus ohirai metacercariae induced by a bile salt, sodium cholate. At a concentration of 10 microM, bepridil, a non-selective Ca(2+) channel blocker, completely inhibited in vitro excystment, whereas TEA, lidocaine, and R(+)-IAA-94, channel blockers against K(+), Na(+) and Cl(-) ions, respectively, benzamil, an Na(+)/H(+) and Na(+)/Ca(2+) ion exchanger blocker, and R(+)-DIOA, a [K(+), Cl(-)] cotransporter inhibitor, did not. Considering the previous result that Ca(2+) ionophores are also efficient inducing factors for in vitro excystment of P. ohirai metacercariae and the present result, bile salts appear to induce the excystment of P. ohirai metacercariae through evoking the Ca(2+) channels of target cells within the metacercarial juveniles.

Animals↗
PubMed1982

Mixed association of cholesterol with methyl cholate and methyl lithocholate in chloroform solutions.

The concentration-dependent mixed association behavior of cholesterol with methyl cholate (MeC) and methyl lithocholate (MeLC) in chloroform at 37 degrees C has been studied by vapor pressure osmometry (VPO). This study is part of a larger project to investigate the effect of number and position of hydroxyl-bearing steroids. Using theories developed by Adams and by Steiner, the model and appropriate parameters for the nonideal mixed associations were elucidated. For the MeLC/cholesterol system, no mixed association was observed. For the MeC/cholesterol system, both methods of analysis indicate that a nonideal AB complex formation occurs. The best parameters to explain the experimental data are kAB = 0.04 1/g; BAB (the nonideal term) = 1.5 X 10(-5) 1 mol g-2.

Chemical Phenomena↗
PubMed2006

Stimulation of polyprenyl 4-hydroxybenzoate transferase activity by sodium cholate and 3-[(cholamidopropyl)dimethylammonio]-1-propanesulfonate.

Polyprenyl 4-hydroxybenzoate transferase (Coq2p) plays a central role in ubiquinone biosynthesis. Coq2p mediates the conjugation of 4-hydroxybenzoate, the benzoquinone ring precursor, with the completed side chain. The activity is most easily assayed by measuring the rate of incorporation of 4-hydroxybenzoate as radiolabeled substrate into polyprenyl 4-hydroxybenzoate. The in vitro assay requires addition of a detergent into the reaction mixture to activate enzyme activity, and Triton X-100 is used for this purpose in the routine assay. We have found that both 3-[(cholamidopropyl)dimethylammonio]-1-propanesulfonate and sodium cholate, but not sodium deoxycholate, lysophosphatidyl choline, or octylglucoside, significantly stimulate the activity over that measured with Triton X-100. High-performance liquid chromatography analysis of lipid extracts revealed that the increase of specific activity resulted in a similar increase in reaction product, this effect is due not merely to a better lipid extraction but also to the actual stimulation of enzyme activity. With our improved method, we were able to measure Coq2p activity with much greater sensitivity in both fresh and frozen/thawed mitochondria and in crude homogenates obtained from cultured cells. Our method will simplify evaluation of Coq2p activity in scarce biological materials, such as cells obtained from human tissue biopsies, and thus it will facilitate the biochemical characterization of ubiquinone deficiencies.

Alkyl and Aryl Transferases↗