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After electron impact in the mass spectrometer, 24,24-diphenyl-23-ene derivatives of cholic acid ejected the 17-sidechain as an ionized 1,1-diphenyl-butadiene derivative, and the 12 alpha-acetoxy group activated this loss. This contrasts markedly with the mass spectrometric fragmentation of typical sterols having unsaturated 17-sidechains that are also devoid of functionality on the C-ring.
Molecular species of phosphatidylcholines were analyzed in hepatic and gallbladder bile obtained from six subjects with adenomyoma of the gallbladder (gallstone-free controls) and 27 gallstone patients undergoing cholecystectomy. Seven of the gallstone patients had been treated with cholic acid and seven with chenodeoxycholic acid for at least 8 weeks before operation. The two predominant species were 1-palmitoyl-2-oleoyl- and 1-palmitoyl-2-linoleoyl-sn-glycerophosphocholines which together accounted for 75-80% of the total amount of phosphatidylcholines. Minor species were 1-palmitoyl-2-palmitoleoyl-, 1-stearoyl-2-linoleoyl-, 1-oleoyl-2-linoleoyl-, and 1-palmitoyl-2-arachidonoyl-sn-glycerophosphocholines. Gallstone patients had a higher portion of the 1-palmitoyl-2-oleoyl species and a concomitant lower proportion of the 1-palmitoyl-2-linoleoyl species than gallstone-free subjects. The ratio between the two species was about 0.7 and 0.4, respectively, in the hepatic bile of the two groups of patients. Treatment with bile acids was associated with a normalization of the pattern of phosphatidylcholines.
Mimics of squalamine and polymyxin B (PMB) have been prepared from cholic acid in hope of finding new antimicrobial agents. The squalamine mimics include the polyamine and sulphate functionalities found in the parent antibiotic, however, the positions relative to the steroid nucleus have been exchanged. The PMB mimics include the conservation of functionality among the polymyxin family of antibiotics, the primary amine groups and a hydrophobic chain. Although the squalamine and PMB mimics are morphologically dissimilar, they display similar activities. Both are simple to prepare and demonstrate broad spectrum antimicrobial activity against Gram-negative and Gram-positive organisms. Specific examples may be inactive alone, yet effectively permeabilise the outer membranes of Gram-negative bacteria rendering them sensitive to hydrophobic antibiotics. Problems associated with some of the squalamine and PMB mimics stem from their haemolytic activity and interactions with serum proteins, however, examples exist without these side effects which can sensitise Gram-negative bacteria to hydrophobic antibiotics.
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Primary bile acid concentrations were measured in serum of 332 newborns with neonatal hyperbilirubinemia (serum total bilirubin level greater than 200 mumol/l) and compared with those of 95 nonhyperbilirubinemic neonates (serum total bilirubin level less than 200 mumol/l). The serum concentrations (mumol/l; mean +/- SEM) for cholic acid (8.78 +/- 0.44) and chenodeoxycholic acid (10.5 +/- 0.68) were significantly higher (p less than 0.001) in the hyperbilirubinemic group than in the controls (7.16 +/- 0.48 and 6.67 +/- 0.48, respectively). 80 (24%) of the hyperbilirubinemic newborns had true cholestasis (serum levels of cholic and/or chenodeoxycholic acid higher than mean +/- 2 SD in the reference group). The ratio of cholic to chenodeoxycholic acid was significantly higher (p less than 0.05) in the cholestatic group than in the hyperbilirubinemic newborns without cholestasis. There was no significant differences in the serum concentrations of alkaline phosphatase or lactate dehydrogenase between the cholestatic and noncholestatic groups. In the hyperbilirubinemic newborns, the primary bile acids were indiscriminately raised. Only 8 infants from the 332 newborns had jaundice at the age of 1 month. Of these 8 infants only 2 had neonatal cholestatic hyperbilirubinemia. It thus appears that measurement of serum primary bile acid concentrations has only limited diagnostic value in assessing the severity or prognosis of neonatal hyperbilirubinemia.
In 12 patients with Laennec's cirrhosis conjugated cholic acid was measured by radioimmunoassay simultaneously in the portal vein, the aorta, and the hepatic vein. Furthermore, the concentration was measured for 90 minutes after i. v. injection of cholecystokinin. In the fasting patient the porto-venous extraction ratio was 0.45 (SD 0.23) and the arterio-venous extraction ratio was 0.24 (SD 0,21). 15-30 minutes after cholecystokinin the bile acid concentration significantly increased. In this time the porto-venous extraction ratio rose to 0.71 while the aorto-venous extraction ratio was different. These results agree with the hemodynamics found in cirrhosis. After cholecystokinin the increase in the extraction ratio account for the blood loss by porto venous shunts which corresponds to an increase of the portal compartment.
Seven patients with radiolucent stones in the gallbladder and two patients with radiolucent stones in the biliary tree were treated with oral cholic acid and purified soya-bean lecithin for 6 months. In two patients the stones disappeared and in one patient the stones were reduced in size. In five patients fasting bile samples were obtained before and during treatment and assayed for cholesterol, bile acid, and phospholipid. In all five patients the lithogenic index of bile was reduced during treatment. The biliary deoxycholic acid concentration was increased and chenodeoxycholic acid concentration decreased during treatment.
PURPOSE: This study was conducted to assess the suitability of insulin analogs acylated by various cholic acid derivatives for use as basal insulin, and to test the most promising of these, LysB29(Nepsilon-lithocholyl-gamma-Glu) des(B30) human insulin (NN344) in pigs. METHODS: Circular dichroism spectroscopy and size-exclusion chromatography were used to explore the physicochemical properties of the analogs, and affinities for albumin and insulin receptors were determined. After subcutaneous injection in pigs, disappearance half-times were measured, and the plasma profile and glucose-lowering effect in a euglycemic clamp were assessed for NN344. RESULTS: NN344 showed glucose-lowering activity lasting more than 24 h. Glucose infusion rate was essentially constant from 5 to 19 h after injection. NN344 seemed to be a dodecamer in the presence of zinc ions and phenol. Without phenol, the apparent molecular mass was >5000 kDa. Formation of such a self-assembly at the site of s.c. injection and its subsequent slow decomposition might explain the long duration of action of NN344. A measurable affinity for albumin of the lithocholic acid ligand may also contribute to the prolonged action. CONCLUSIONS: NN344 is a candidate for a neutral soluble basal insulin that might offer people with diabetes a prolonged duration, smooth, and predictable basal insulin supplement.
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The objective of the study was to establish whether cholic acid (CHA) enhanced colonic tumor incidence in the early phase of carcinogenesis. Male, Sprague-Dawley rats (n = 180) were injected twice with azoxymethane (AOM) (15 mg x kg(-1) body weight x week(-1), s.c., given 1 week apart). Following the first AOM injection, animals were randomly assigned to two groups, control AIN-93G diet (CON) or control diet containing 0.2% CHA by weight (CHA). Three weeks after the first injection, 20 animals (10 animals/group) were killed and aberrant crypt foci (ACF) were enumerated. The remaining animals were further subdivided and animals randomly assigned to CON or CHA diets, creating four treatments: CON-CON, CON-CHA, CHA-CHA, and CHA-CON. After 3, 12, and 20 weeks (following the first carcinogen injection), the animals were killed and the number and crypt multiplicity of ACF enumerated. Macroscopic tumors were evaluated at week 20. Total ACF were not different between groups. Average crypt multiplicity and medium (4-6 crypts/focus) and large (> or = 7 crypts/focus) ACF were greater in CHA-CHA and CHA-CON compared with CON-CON and CON-CHA (p < 0.01). Transient exposure to CHA (CHA-CON) was sufficient to induce development of ACF with an accelerated growth phenotype and elicit a tumor-enhancing effect. CHA-CHA had the highest tumor incidence (82.8%, p < 0.05) followed by CHA-CON (56.7%, p < 0.05), and tumor multiplicity and number of tumors per rat in CHA-CON were similar to CHA-CHA (2.29 and 1.3 versus 2.33 and 1.9, respectively). Delayed intervention with CHA (CON-CHA) produced a tumor outcome similar to CON-CON (31 and 30%, respectively), it did not enhance colonic tumor incidence. Taken collectively these results suggest CHA was effective in enhancing colon carcinogenesis during early phases and ineffective in post-initiation phases.
A new class of poly(ethylene glycol) derivative, Chol-PEG-A, having both cholesteryl- and amino-pendant groups (2.89 and 5.39 groups per polymer molecule, respectively) was synthesized. This amphiphilic PEG derivative forms a cationic polymer assembly in water. Chol-PEG-A expressed high transfection efficiency in the serum-free medium at relatively low amine/phosphate (N/P) ratios (1.3-1.5), whereas PEG-A, having only amino pendants without the cholesteryl side chain could transfect the cells only at a very high N/P ratio (83). The efficiency remarkably decreased by addition of fetal bovine serum (FBS) to the medium. Mixing of cholic acid to Chol-PEG-A gave a neutralized polyion complex, and the interaction with serum proteins was evidently suppressed. This Chol-PEG-A-cholic acid system showed higher gene expression even in the FBS-containing medium and as high a transfection efficiency as a Superfect.
Sterol 27-hydroxylase (CYP27) participates in the conversion of cholesterol to bile acids. We examined lipid metabolism in mice lacking the Cyp27 gene. On normal rodent chow, Cyp27(-/-) mice have 40% larger livers, 45% larger adrenals, 2-fold higher hepatic and plasma triacylglycerol concentrations, a 70% higher rate of hepatic fatty acid synthesis, and a 70% increase in the ratio of oleic to stearic acid in the liver versus Cyp27(+/+) controls. In Cyp27(-/-) mice, cholesterol 7alpha-hydroxylase activity is increased 5-fold, but bile acid synthesis and pool size are 47 and 27%, respectively, of those in Cyp27(+/+) mice. Intestinal cholesterol absorption decreases from 54 to 4% in knockout mice, while fecal neutral sterol excretion increases 2.5-fold. A compensatory 2.5-fold increase in whole body cholesterol synthesis occurs in Cyp27(-/-) mice, principally in liver, adrenal, small intestine, lung, and spleen. The mRNA for the cholesterogenic transcription factor sterol regulatory element-binding protein-2 (SREBP-2) and mRNAs for SREBP-2-regulated cholesterol biosynthetic genes are elevated in livers of mutant mice. In addition, the mRNAs encoding the lipogenic transcription factor SREBP-1 and SREBP-1-regulated monounsaturated fatty acid biosynthetic enzymes are also increased. Hepatic synthesis of fatty acids and accumulation of triacylglycerols increases in Cyp27(-/-) mice and is associated with hypertriglyceridemia. Cholic acid feeding reverses hepatomegaly and hypertriglyceridemia but not adrenomegaly in Cyp27(-/-) mice. These studies confirm the importance of CYP27 in bile acid synthesis and they reveal an unexpected function of the enzyme in triacylglycerol metabolism.
BACKGROUND AND AIMS: Cholestasis is associated with retention of potentially toxic bile acids and alterations in hepatocellular transporter expression. Conversely, nontoxic ursodeoxycholic acid (UDCA) stimulates bile secretion and counteracts cholestasis. This study aimed to determine the effects of UDCA and cholic acid (CA) on the expression of hepatocellular transporters for bile acids (Ntcp, Bsep), organic anions (Oatp1, Mrp2), organic cations (Mdr1a/b), and phospholipids (Mdr2) in mouse liver. METHODS: Bile flow/composition was analyzed in UDCA- or CA-fed mice. Transporter expression was studied by reverse-transcription polymerase chain reaction, Western blotting, and immunofluorescence microscopy. RESULTS: UDCA had no effect on basolateral Ntcp and down-regulated Oatp1, whereas canalicular Bsep and Mrp2 were up-regulated. CA down-regulated basolateral Ntcp and Oatp1, whereas canalicular Bsep, Mrp2, and Mdr1a/b were up-regulated. Neither UDCA nor CA affected Mdr2 expression. Both UDCA and CA stimulated biliary bile acid and glutathione excretion, although only CA increased phospholipid and cholesterol excretion. CONCLUSIONS: Down-regulation of basolateral and up-regulation of canalicular transporters in response to CA may represent a defense mechanism, in an attempt to prevent hepatocellular accumulation of potentially toxic bile acids. The therapeutic effects of UDCA may be caused in part by stimulation of canalicular transporter expression in the absence of hepatocellular toxicity.
The three-dimensional structure of a covalent hybrid between cholic acid and the self-complementary DNA hexamer 5'-TGCGCA-3' was solved via two-dimensional NMR and restrained torsion angle molecular dynamics. In the complex, refined to a pairwise rmsd of 0.64 A, the steroid binds to the terminal T:A base pairs via extensive van der Waals contacts but without any hydrogen bonds or detectable dipole-dipole interactions. The contacts involve the methyl groups as well as one edge of the streoid's sterane skeleton and both nucleobases and the deoxyriboses of the terminal base pair of the DNA. The surprising shape complementarity between steroid and the undisturbed DNA termini explains the increase in fidelity and affinity observed for hybridization probes bearing bile acid residues. Since the hydroxyl groups of the steroid do not contribute to the binding of the DNA, they may be derivatized, potentially giving access to a new class of specific binders for blunt ends of Watson-Crick duplexes.
The self-aggregation of the sodium salt of a new adamantyl amide of the 3beta-amino derivative of cholic acid (Na-AdC) in aqueous solution has been investigated by surface tension, dynamic light scattering, fluorescence, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM) measurements. These last two techniques suggest that a lamellar phase, consisting of charged bilayers of Na-AdC separated by solvent and periodically stacked, is formed in aqueous solution. The structure of the bilayer is inferred from the resolution of the crystal of the compound in its acid form. The adamantyl moieties, which are mutually interlocked, reside in the central region of the bilayer, and the carboxylic groups are directed toward the hydrophilic region. The structure is open enough to allow water molecules to interact with a fluorescence probe located at the central hydrophobic region.
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