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PubMed1985

Plasma bile salt levels in patients presenting with generalised pruritus: an improved indicator of occult liver disease.

Fasting plasma bile salt concentrations were measured in 26 patients presenting to a Skin Department who had generalised pruritus without primary skin disease, as part of a screening investigation for systemic causes of pruritus. The results were compared with conventional tests of hepatic function. Plasma-conjugated cholate measurements identified all patients with hepatobiliary disease. Conventional liver function tests were abnormal in these patients but also in five patients with no other evidence of hepatic dysfunction. Fasting conjugated-cholate measurements offer a useful screening test for identifying hepatobiliary disease in patients presenting with generalised pruritus.

Adult↗

PubMed2004

Cytotoxicity studies of Dynasan 114 solid lipid nanoparticles (SLN) on RAW 264.7 macrophages-impact of phagocytosis on viability and cytokine production.

Solid lipid nanoparticles (SLN) based on Dynasan 114 (D114) were tested using RAW 264.7 cells. The influence of different surfactants on the cytotoxicity of this type of SLN was examined, expressed as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) viability and the production of cytokines such as interleukin 6 (IL-6), IL-12 and tumour necrosis factor-alpha (TNF-alpha). Results were compared with previously obtained data when peritoneal mouse macrophages were used. SLN produced with stabilizers/surfactants such as poloxamer 188, sodium cholate, Lipoid S75, Tween 80, Poloxamine 908 and sodium dodecylsulfate were shown to be nontoxic towards RAW 264.7 cells. Cytokine production was reduced and stimulation, expressed in elevated cytokine levels, could not be found. Using cetylpyridinium chloride (CPC) as stabilizing surfactant, SLN became cytotoxic in a concentration-dependent manner. Not only were the viabilities reduced but also cytokine production. Cytotoxic effects of CPC stabilized SLN could be antagonized using cytochalasin B to block phagocytosis. D114-SLN produced with pharmaceutically accepted surfactants for intravenous injection (poloxamer 188, Lipoid S75, sodium cholate, Tween 80) were very well tolerated by the cells. Even sodium dodecylsulfate-stabilized D114-SLN did not exert toxic effects. Comparison of the RAW 264.7 data with previously obtained data from toxicity studies of D114-SLN towards peritoneal mouse macrophages showed similar results. This offers the possibility of using the RAW 264.7 cell line for cytotoxicity studies of colloidal drug carrier systems, rather than using laboratory animals as source of macrophages for these kinds of studies.

Animals↗

PubMed1983

Inhibition of carp liver mitochondrial monoamine oxidase by some commonly-used detergents.

The inhibitory effects of some detergents commonly used in biochemical research on carp liver mitochondrial monoamine oxidase were examined. Sodium dodecylsulfate, octyl-beta-D-glucopyranoside, sodium cholate and Triton X-100 at relatively low concentrations caused strong dose-dependent inhibition of the activity towards tyramine, but digitonin caused only weak inhibition. Sodium dodecylsulfate, octyl-beta-D-glucopyranoside and sodium cholate caused almost complete inhibition of activity in the concentration ranges tested. The extent of inhibition by Triton X-100 was greater after preincubation at 37 degrees C for 30 min than that without preincubation, but with or without preincubation, the inhibition was not substrate-selective and was not complete at a relatively high concentration (2%) of Triton X-100. Without preincubation, the mode of inhibition by Triton X-100 was competitive and reversible with respect to the oxidations of 5-HT, tyramine and PEA, but after preincubation (37 degrees C for 30 min), it became noncompetitive and irreversible, depending on the concentration of detergent used. These findings suggest that it had different actions on the enzyme depending on preincubation. Triton X-100 also slightly changed enzyme sensitivity towards clorgyline and deprenyl, regardless of the preincubation time or the substrate used. Some possible mechanisms of the inhibitory effect of Triton X-100 are discussed.

Animals↗

PubMed1988

Assessment of discomfort in rats with hepatomegaly.

An attempt was made to assess discomfort in rats with hepatomegaly induced by feeding a high cholesterol, high cholate diet. After 8 weeks, the rats displayed a more than two-fold increase in liver weight when compared with controls fed a commercial diet. In a small open field test, behaviour of rats with hepatomegaly was similar to the controls. Of 9 parameters scored per rat, only the response to pressure on the right hypochondrium (tension of overlying muscles) scored higher than in control animals. There was considerable between-assessor variation in the assignment of scores. It is suggested, tentatively, that hepatomegaly in rats caused by cholesterol plus cholate feeding, may not cause extreme discomfort. Upon 'blind' palpation of control and test rats, an average of 60% of the rats with hepatomegaly were classified correctly.

Animals↗

PubMed2005

O-palmitoylcurdlan sulfate (OPCurS)-coated liposomes for oral drug delivery.

O-Palmitoylcurdlan sulfate (OPCurS) was applied to the liposomal surface to improve the stability of liposomes. To synthesize OPCurS, curdlan was chemically sulfated and then modified with a palmitoyl derivative. The synthesized OPCurS was characterized by Fourier transform-infrared spectroscopy (FT-IR). OPCurS-coated liposomes prepared by the solvent evaporation method were characterized for size, shape, surface charge, and stability in simulated gastric fluid (SGF) and sodium cholate solution. The sizes of OPCurS-coated liposomes increased with the OPCurS content of liposomes and zeta potential decreased when OPCurS was applied to the liposomal surface. With the increase in the content of OPCurS attached to the liposomal surface, the stability of liposomes in SGF and sodium cholate solution was gradually induced and the stability was most improved at a lipid/OPCurS weight ratio of 1.5. Liposomes not coated with OPCurS released 99.5+/-2.3% of the initial 5-carboxyfluorescein (5-CF) content, whereas OPCurS-coated liposomes released 53.7+/-3.7%. OPCurS on the surface of liposomes suppressed the release of 5-CF. Theses results indicate that OPCurS-coated liposomes can be effectively used as a drug delivery carrier via oral administration.

Administration, Oral↗

PubMed1996

Efficient lipase-catalyzed preparation of long-chain fatty acid esters of bile acids: biological activity and synthetic application of the products.

A highly regioselective (3-position) and efficient (quantitative yield) acylation of bile acids catalyzed by immobilized Candida antarctica lipase was established. Methyl cholate derivatives acylated with long-chain fatty acids (C12-C16) showed an inhibitory effect on the growth of some strains of Gram-positive and -negative bacteria (27-400 micrograms/ml). The anti-bacterial activity was slightly weaker than has been observed for methyl cholate, while the increased lipophilicity and lower melting points of the present derivatives are well suited for a potential germicide which would be safe and be topically applied. This enzyme-catalyzed transesterification is also demonstrated as an expeditious route to ursodeoxycholic acid, in respect of the regioselective introduction of acyl protecting groups on the hydroxyl groups of the intermediates. 7-Ketolithocholic acid, a known direct precursor of ursodeoxycholic acid, was obtained from cholic acid via chenodeoxycholic acid in a 46% yield and 9 steps.

Acylation↗

PubMed1997

ATP and ADP bind to cytochrome c oxidase and regulate its activity.

By equilibrium dialysis of cytochrome c oxidase from bovine heart with [35S]ATPalphaS and [35S]ADPalphaS, seven binding sites for ATP and ten for ADP were determined per monomer of the isolated enzyme. The binding of ATP occurs in a time-dependent manner, as shown by a filtration method, which is apparently due to slow exchange of bound cholate. In the crystallized enzyme 10 mol of cholate were determined and partly identified in the high resolution crystal structure. Binding of ADP leads to conformational changes of the Tween 20-solubilized enzyme, as shown by a 12% decrease of the gamma-band. The conformational change is specific for ADP, since CDP, GDP and UDP showed no effects. The spectral changes are not obtained with the dodecylmaltoside solubilized enzyme. The polarographically measured activity of cytochrome c oxidase is lower after preincubation with high ATP/ADP-ratios than with low, in the presence of Tween 20. This effect of nucleotides is due to interaction with subunit IV, because preincubation of the enzyme with a monoclonal antibody to subunit IV released the inhibition by ATP. In the presence of dodecylmaltoside the enzyme had a 2 to 3-fold higher total activity, but this activity was not influenced by preincubation with ATP or ADP.

Adenosine Diphosphate↗

PubMed1996

Purification of the CIC-0 chloride channel from Torpedo california electroplax identification of a phosphorylation site for cAMP-dependent protein kinase.

The voltage-gated chloride channel (CIC-0) from the electric organ of Torpedo californica was purified by immunoaffinity chromatography. A polyclonal antibody was shown to specifically recognize the CIC-0 channel (M(r) 85,000-90,000) in a Western blot of total membrane proteins. As monitored by immunoprecipitation, the formation of antibody-antigen complexes in solution strongly depends on the detergent composition. The highest yield of precipitated CIC-0 was obtained from an incubation mixture containing both an anionic detergent, cholate or lauryl sulfate, and the zwitterionic detergent CHAPS. In contrast, immuno-precipitation of CIC-0 was largely reduced when cholate was exchanged for the nonionic detergent Triton x-100, suggesting that the efficient formation of immuno-complexes is favored by negatively charged detergent. In initial immunopurification experiments, in addition to CIC-0 a major contaminating polypeptide of M(r) approximately 115,000 was copurified, which represents the SITS-binding protein [Jentsch et al. (1989) Biochem. J. 261, 155]. Purification of CIC-0 could be increased from about 35% up to 60% homogeneity when immunoaffinity chromatography was performed in the presence of N-acetylglucosamine. Therefore the highly glycosylated SITS-binding protein most likely interacts with the CIC-0 protein via its carbohydrate parts. The purified CIC-0 channel was found to be phosphorylated by PKA in vitro to a level of 0.35-0.4 mol of phosphate incorporated per mol of CIC-0. Proteolytic digestion with endoproteinase GluC and HPLC-separation revealed two major phosphopeptides, which could be identified by amino acid sequence analysis as different size fragments of the same consensus phosphorylation site. Comparison of the peptide sequences with the deduced protein sequence of CIC-0 [Jentsch et al. (1990) Nature 348, 510; O'Neill et al. (1991) Biochem. Biophys. Acta 1129, 131] indicates serine 600 as the phosphorylated residue. Therefore, our results provide strong evidence that CIC-0 is phosphorylated at this single site by PKA in vitro.

Animals↗

PubMedDate not supplied

Bile salt delipidation, residual phospholipids and reactivation of the Ca2+-ATPase from sarcoplasmic reticulum.

1. Delipidation of the Ca2+-ATPase of sarcoplasmic reticulum membranes by gel chromatography employing ionic detergents (cholate, deoxycholate and mixtures of both) in the presence of glycerol has been studied with respect to residual phospholipids and ATPase activities. 2. The extent of delipidation depends on the detergent chosen and on the ionic strength of the elution buffer. Increasing ionic strength favours a more effective removal of phospholipids, down to about 1 phospholipid molecule per ATPase molecule. 3. The residual ATPase activities of the delipidated preparations are negligibly low. Extensive restoration of the Ca2+-dependent ATPase activity has been achieved by oleic acid, a lysolecithin (myristoylglycerophosphocholine) and a lecithin (dimyristoylglycerophosphocholine). The percentage of reactivation by oleate depends linearly on the amount of residual phospholipids and on the detergent employed. 4. After gel filtration through an Ultrogel or Sepharose column containing 1% cholate in the elution buffer the delipidated ATPase is eluted as a reactivatable high molecular aggregate, whereas 1% deoxycholate favours the formation of completely lipid-free monomeric units which cannot be reactivated, however. A high molecular aggregate is also formed in deoxycholate, the ratio of monomer to polymer depending on the solubilizing and elution conditions. 5. The residual lipids are always composed of a mixture of all different lipid classes present in the native sarcoplasmic vesicles, even at high degrees of delipidation. Specific changes with varying extent of delipidation were not detected.

Animals↗

PubMedDate not supplied

Effect of solvent polarity and viscosity on the guest binding dynamics with bile salt aggregates.

Bile salts form supramolecular aggregates with two binding sites with different properties. The guest binding dynamics to the aggregates and guest protection from species in the aqueous phase were investigated using fluorescence and laser flash photolysis experiments. Sodium cholate, deoxycholate and taurodeoxycholate were used as bile salts and acetonitrile or ethylene glycol were added as co-solvents to water in order to alter the binding properties of 1-ethylnaphthalene and 1-naphthyl-1-ethanol with the aggregates. The binding dynamics are faster and protection efficiencies are lower for guests bound to cholate and in the presence of either co-solvent.

Bile Acids and Salts↗

PubMed1984

Direct measurement of urinary bile acids of infants by high-performance liquid chromatography connected with an enzyme immobilized column.

An accurate and sensitive method by high-performance liquid chromatography connected with 3 alpha-hydroxysteroid dehydrogenase immobilized column for the measurement of urinary bile acids of noncholestatic and cholestatic infants was performed in this study. The purification and group separation of urinary bile acids were done through a piperidinohydroxypropyl Sephadex LH-20 column. By ultraviolet spectromonitor, non 3 alpha-hydroxy bile acids such as 3 beta-hydroxy-5-cholenate were determined, and 3 alpha-hydroxy bile acids by fluorescence spectromonitor. Urinary bile acids in the specimens obtained from noncholestatic and cholestatic infants were determined by this procedure. Major bile acids were cholate, chenodeoxycholate conjugates and cholate unconjugate in healthy infants. In cholestatic infants, total and individual bile acids were extremely increased, and 3 beta-hydroxy-5-cholenate conjugates appeared in the sulfated fraction.

3-Hydroxysteroid Dehydrogenases↗

PubMed1996

Luminal peptide YY-releasing factors in the isolated vascularly perfused rat colon.

Peptide YY (PYY) is produced in endocrine L cells primarily localized in the distal bowel. These open-type L cells make contact with the intestinal chyme which may thus affect their secretory activity. The aim of the present study was to examine a large variety of luminal compounds found in colonic contents for their potential as PYY-releasing factors, using the isolated vascularly perfused rat colon. The release of PYY into the portal effluent was measured by a specific RIA. Luminal administration of 5 mM glucose or 0.5% (w/v) starch for 30 min did not induce significant release of PYY. Oleic acid (10 and 100 mM) also did not significantly increase PYY secretion. A pharmacological concentration of glucose (250 mM) and a mixture of amino acids (total concentration 250 mM) both induced PYY secretion (200% of basal). Pectin, a poly-galacturonic acid, evoked dose-dependent secretion of PYY-like immunoreactivity over the range 0.1-0.5% (w/v). The maximal response was observed after infusion of 0.5% pectin which induced a prompt and sustained release of PYY (300% of basal). Galacturonic acid itself (5%) produced marked PYY secretion. Gum arabic (0.5%) induced a gradual increase in portal PYY concentration (maximal response 250% of the basal value) whereas cellulose (0.5%) did not elicit PYY secretion. Luminal n-butyrate over the range 0.5-5 mM produced a dose-dependent release of PYY (maximal response 300% of the basal value with 5 mM n-butyrate). Increasing the concentration of n-butyrate to 100 mM provoked a gradual decrease in PYY secretion. Propionate was a less potent stimulant than n-butyrate, and acetate did not increase PYY secretion above the basal value. At a concentration of 2 or 20 mM, taurocholate, cholate and deoxycholate brought about PYY secretion while hyodeoxycholate was without effect. In conclusion, glucose and amino acids may mediate PYY release but only when they are present at high supraphysiological concentrations in the colon while oleic acid does not produce any PYY secretion. Physiological concentrations of fibers (pectin, gum arabic), short-chain fatty acids (n-butyrate, propionate) and bile salts (taurocholate, cholate, deoxycholate) are all potent stimulants of PYY release. Whether the release of PYY by luminal factors is coupled to water and electrolyte transfer via a local/paracrine pathway remains an open question which requires additional work with the isolated vascularly perfused colon preparation.

Amino Acids↗

PubMedDate not supplied

Poly(4-vinylpyridine)-coated liposomes: stability studies and release of acetylsalicylic acid.

Liposomes of dimyristoylphosphatidylcholine (DMPC) and dicetylphosphate (DCP) reacted with 4-vinylpyridine (4-VP) to form a salt and, subsequently, autopolymerized for form poly(4-vinylpyridine) (poly(4-VP))-coated liposomes. The conditions for optimization of polymer coating have been determined; also, the effects of polymer coating on liposome stability, the encapsulation of ASA and its release kinetics have been measured. The coating efficiency was maximum at a DMPC:DCP 1:1 mole ratio, at pH 4.0 in acetate buffer, and a polymerization time of 40 min. The polymer-coated liposomes were stable in 2 mM sodium cholate and 4 per cent isopropanol solutions, as determined from turbidity measurements, versus a 20-25% decrease in stability of uncoated liposomes. The encapsulation efficiency of ASA reached a maximum of 9 per cent at DMPC:DCP 1:1 mole ratio. The release of ASA at 37 degrees C, pH 7.0 was characterized by an initial fast release (85 and 63 per cent in 20 min from uncoated and polymer-coated liposomes, respectively) followed by a slow, constant release rate up to 140 min. Thus, autopolymerization of a polymerizable monomer at liposome surfaces represents a potentially feasible stabilization approach for liposomes exposed to sodium cholate solutions with greater retention of solute than uncoated liposomes.

Aspirin↗

PubMedDate not supplied

Encapsulation of calcitonin in liposomes depends on the vesicle preparation method.

Calcitonin-loading was studied in liposomes composed of phosphatidylcholine, cholesterol and stearylamine in relation to the vesicle preparation method. Liposomes entrapping calcitonin were prepared by extrusion, sonication or from mixed micelles through the elimination of cholate by gel filtration. To understand the mode of calcitonin encapsulation in the vesicles, riboflavin was entrapped within the vesicles and taken as a simple model for the encapsulation of molecules in the aqueous phase. Interactions of calcitonin with the liposomal membranes were evaluated by studying the fixation of radiolabelled calcitonin to the outer surface of empty liposomes, and by preparing calcitonin-loaded LDL-like nanoparticles composed of phosphatidylcholine and cholesteryloleate. Calcitonin entrapment in the vesicles depends largely on the vesicle preparation method. When vesicles are prepared by removal of cholate from mixed micelles, relatively little calcitonin entrapment in the liposomes is obtained. In this type of vesicle, calcitonin is exclusively embedded in the vesicle bilayer. When vesicles are prepared by extrusion or sonication, calcitonin is found both in the aqueous and lipidic phases of the vesicles. Optimal calcitonin encapsulation was obtained when the liposomes were prepared by sonication.

Animals↗

PubMed1996

Application of cloth-based enzyme immunoassay for the characterization of monoclonal antibodies to Salmonella lipopolysaccharide antigens.

The specificity, detection limit, and stability of twelve anti-Salmonella monoclonal antibodies (Mabs) were evaluated by cloth-based enzyme immunoassay (CEIA) and polymyxin-cloth based enzyme immunoassay (p-CEIA). Using the p-CEIA, five Mabs were found to react with cholate extracted lipopolysaccharide (LPS) antigens of all 44 Salmonella strains representing 19 different serogroups examined, with the exception of the one strain of serogroup-O tested. These five Mabs did not react with cholate extracts of any of 16 Gram-positive or Gram-negative non-Salmonella bacteria tested. The detection limit of purified S. typhimurium LPS antigen in the p-CEIA was approximately 40 ng for four of the Mabs and approximately 20 ng for the other Mab. Four of the five Mabs were stable during storage at 22 degrees C-23 degrees C for 24 h. These four Mabs are potentially useful for the immunodetection of Salmonella in foods and other samples.

Antibodies, Monoclonal↗

PubMed1979

Influences of oyster or clam feeding on lipid metabolism in rats.

Rats were fed on three kinds of diets for two weeks: (I) basal diet, (II) containing 0.1% cholate and (III) containing 0.1% cholesterol and 0.1% cholate. Each dietary group was further divided into subgroups to whose diet was added 0, 5 or 10% (dry weight) of minced oyster (Callocorchina) or clam (Tapes japonica). The serum and liver cholesterol levels of the rats fed the basal diet were reduced by feeding oyster or clam. The serum and liver triglyceride levels of all dietary groups were lowered markedly by feeding oyster or clam. The activities of glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were markedly reduced in the basal groups fed oyster or clam. These effects were observed in 5 and 10% shellfish feeding. These shellfish may be considered hypolipidemic foods.

Acetyl-CoA Carboxylase↗

PubMed1985

Effects of cycloartenol on absorption and serum levels of cholesterol in rats.

The possibility that cycloartenol magnifies the hypocholesterolemic effect of beta-sitosterol was studied in two strains of rats fed on cholesterol-enriched (0.5%) diets. Cycloartenol was added to diets containing 1.0% or 0.5% beta-sitosterol at the 0.05% level and to diet free of plant sterol at the 0.5% level. In one experiment, diets included sodium cholate (0.125%). Due to the potent hypocholesterolemic efficacy of beta-sitosterol under the present dietary regimens, no clear additional effect (so-called synergistic effect) of cycloartenol was observed. However, in the experiment using Wistar rats, the decrease in serum apo A-I due to feeding cholesterol was ameliorated more effectively in combination with beta-sitosterol than with beta-sitosterol alone. The hepatic deposition of cholesterol was mitigated by dietary beta-sitosterol, and further, although slightly, by a combination of beta-sitosterol and cycloartenol, except in the experiment with diets containing sodium cholate. Fecal excretion of neutral and acidic steroids was not meaningly magnified by cycloartenol. Cycloartenol itself was not as effective as beta-sitosterol in mitigating lipid disorders due to dietary cholesterol. The rate of appearance of cholesterol in the thoracic duct lymph was not interfered with further by a combination of beta-sitosterol and cycloartenol compared to beta-sitosterol alone. This trimethylsterol was absorbed at a rate approximately 4-fold higher than that of beta-sitosterol, though much lower compared to cholesterol. These results suggest a preference for cycloartenol in cholesterol dynamics. However, cycloartenol seems unlikely to influence cholesterol absorption in the small intestine.

Animals↗

PubMedDate not supplied

Mixed micelle proliposomes for preparation of liposomes containing amphotericin B, in-vitro and ex-vivo studies.

The aim of this work was to produce a form of injectable liposomes containing amphotericin B derived from mixed micelle proliposomes. Mixed micelles were derived from a mixture of lecithin/sodium cholate in aqueous media. The solubility of amphotericin B in proliposomes was studied as a function of lipid composition (total lipid concentration, molar ratio of lecithin/sodium cholate), and the dispersion media (pH, ionic strength, presence or absence of human serum albumin), and the temperature. The data show that micelle-->liposome transformation occurs during the dilution of proliposomes containing amphotericin B. These transformations could be followed via transmission electron microscopy (TEM). Data related to dilution of proliposomes as well, show that under no circumstance there occurs any precipitation that might be assigned to the decreased solubility of amphotericin B. These indicate that the incorporated drug also participates during the transformation of the proliposomes into liposomes. It is thus concluded that mixed micelle proliposomes are prime candidates for the production of a form of injectable amphotericin B in liposomes.

Amphotericin B↗