Unique bile acid profiles in the bile ducts of patients with primary sclerosing cholangitis.

BACKGROUND: The relationship between primary sclerosing cholangitis (PSC) and biliary bile acids (BAs) remains unclear. Although a few studies have compared PSC biliary BAs with other diseases, they did not exclude the influence of cholestasis, which affects the composition of BAs. We compared biliary BAs and microbiota among patients with PSC, controls without cholestasis, and controls with cholestasis, based on the hypothesis that alterations in BAs underlie the pathophysiology of PSC. METHODS: Bile samples were obtained using endoscopic retrograde cholangiopancreatography from patients with PSC (n = 14), non-hepato-pancreato-biliary patients without cholestasis (n = 15), and patients with cholestasis (n = 13). RESULTS: The BA profiles showed that patients with PSC and cholestasis controls had significantly lower secondary BAs than non-cholestasis controls, as expected, whereas the ratio of cholic acid/chenodeoxycholic acid in patients with PSC was significantly lower despite cholestasis, and the ratio of (cholic acid + deoxycholic acid)/(chenodeoxycholic acid + lithocholic acid) in patients with PSC was significantly lower than that in the controls with or without cholestasis. The BA ratio in the bile of patients with PSC showed a similar trend in the serum. Moreover, there were correlations between the alteration of BAs and clinical data that differed from those of the cholestasis controls. Biliary microbiota did not differ among the groups. CONCLUSIONS: Patients with PSC showed characteristic biliary and serum BA compositions that were different from those in other groups. These findings suggest that the BA synthesis system in patients with PSC differs from that in controls and patients with other cholestatic diseases. Our approach to assessing BAs provides insights into the pathophysiology of PSC.

Validation of Recombinant Chicken Liver Bile Acid Binding Protein as a Tool for Cholic Acid Hosting.

Bile acids (BAs) are hydroxylated steroids derived from cholesterol that act at the intestinal level to facilitate the absorption of several nutrients and also play a role as signaling molecules. In the liver of various vertebrates, the trafficking of BAs is mediated by bile acid-binding proteins (L-BABPs). The ability to host hydrophobic or amphipathic molecules makes BABPs suitable for the distribution of a variety of physiological and exogenous substances. Thus, BABPs have been proposed as drug carriers, and more recently, they have also been employed to develop innovative nanotechnology and biotechnology systems. Here, we report an efficient protocol for the production, purification, and crystallization of chicken liver BABP (cL-BABP). By means of target expression as His6-tag cL-BABP, we obtained a large amount of pure and homogeneous proteins through a simple purification procedure relying on affinity chromatography. The recombinant cL-BABP showed a raised propensity to crystallize, allowing us to obtain its structure at high resolution and, in turn, assess the structural conservation of the recombinant cL-BABP with respect to the liver-extracted protein. The results support the use of recombinant cL-BABP for the development of drug carriers, nanotechnologies, and innovative synthetic photoswitch systems.

Primary 12α-Hydroxylated Bile Acids Lower Hepatic Iron Concentration in Rats.

BACKGROUND: Primary 12α-hydroxylated bile acids (12αOH BAs) enhance intestinal iron uptake due to their ability ex vivo to chelate iron. However, no information is available on their role in vivo, especially in the liver. OBJECTIVES: To investigate the effects and mechanisms of primary 12αOH BAs on hepatic iron concentration in vivo. METHODS: Male Wistar King A Hokkaido male rats (WKAH/HkmSlc) rats aged 4-5 weeks were fed a control diet or a diet with cholic acid (CA; 0.5 g/kg diet), the primary 12αOH BA, for 2 weeks (Study 1) or 13 weeks (Study 2). In Study 3, rats fed the same diets were given drinking water either alone or containing vancomycin (200 mg/L) for 6 weeks. The variables measured included food intake (Studies 1-3), bile acid profiles (Studies 1 and 3), hepatic iron concentration (Studies 1-3), fecal iron excretion (Studies 1 and 2), iron-related liver gene expression (Studies 2 and 3), and plasma iron-related factors (Studies 2 and 3). RESULTS: In Study 1, CA feed reduced the hepatic iron concentration (-16%; P = 0.005) without changing food intake or fecal iron excretion. In Study 2, we found a significant increase in the aortic plasma concentration of lipocalin 2 (LCN2; +65%; P < 0.001), an iron-trafficking protein. In Study 3, we observed no effect of vancomycin treatment on the CA-induced reduction of hepatic iron concentration (-32%; P < 0.001), accompanied by increased plasma LCN2 concentration (+72%; P = 0.003), in the CA-fed rats despite a drastic reduction in the secondary 12αOH BA concentration (-94%; P < 0.001) in the aortic plasma. CONCLUSIONS: Primary 12αOH BAs reduced the hepatic iron concentration in rats. LCN2 may be responsible for the hepatic iron-lowering effect of primary 12αOH BAs by transporting iron out of the liver.

A combination of three plasma bile acids as a putative biomarker for schizophrenia.

The aim of the present study is to determine whether plasma bile acids (BAs) could be used as an auxiliary diagnostic biomarker to distinguish patients with schizophrenia from healthy controls. Seventeen different BAs were quantitatively measured in plasma of 12 healthy participants and 12 patients with schizophrenia. Then, the data were subjected to correlation and linear discriminant analysis (LDA). The concentrations of cholic acid (CA), taurochenodeoxycholic acid (TCDCA) and taurodeoxycholic acid (TDCA) were significantly decreased in plasma of the schizophrenia patients. Correlation analysis showed the concentrations of CA, TCDCA and TDCA were negatively correlated with schizophrenia. In addition, LDA demonstrated that combination of CA, TCDCA and TDCA with a classification formula could predict correctly classified cases and the accuracy of prediction was up to 95.83%. Combination of the three BAs may be useful to diagnose schizophrenia in plasma samples.

Transcriptomic Profiling Identifies Novel Hepatic and Intestinal Genes Following Chronic Plus Binge Ethanol Feeding in Mice.

BACKGROUND: Alcohol-associated liver disease accounts for half of cirrhosis-related deaths worldwide. The spectrum of disease varies from simple steatosis to fibrosis, cirrhosis and ultimately hepatocellular carcinoma. Understanding the disease on a molecular level helps us to develop therapeutic targets. AIM: We performed transcriptomic analysis in liver and ileum from chronic plus binge ethanol-fed mice, and we assessed the role of selected differentially expressed genes and their association with serum bile acids and gut microbiota. METHODS: Wild-type mice were subjected to a chronic Lieber-DeCarli diet model for 8 weeks followed by one binge of ethanol. RNA-seq analysis was performed on liver and ileum samples. Associations between selected differentially regulated genes and serum bile acid profile or fecal bacterial profiling (16S rDNA sequencing) were investigated. RESULTS: We provide a comprehensive transcriptomic analysis to identify differentially expressed genes, KEGG pathways, and gene ontology functions in liver and ileum from chronic plus binge ethanol-fed mice. In liver, we identified solute carrier organic anion transporter family, member 1a1 (Slco1a1; encoding for organic anion transporting polypeptides (OATP) 1A1), as the most down-regulated mRNA, and it is negatively correlated with serum cholic acid level. Prokineticin 2 (Prok2) mRNA, a cytokine-like molecule associated with gastrointestinal tract inflammation, was significantly down-regulated in ethanol-fed mice. Prok2 mRNA expression was negatively correlated with abundance of Allobaculum (genus), Coprococcus (genus), Lachnospiraceae (family), Lactococcus (genus), and Cobriobacteriaceae (family), while it positively correlated with Bacteroides (genus). CONCLUSIONS: RNA-seq analysis revealed unique transcriptomic signatures in the liver and intestine following chronic plus binge ethanol feeding.

High-performance liquid chromatography/electrospray ionisation mass spectrometric characterisation of metabolites produced by Pseudovibrio sp. W64, a marine sponge derived bacterium isolated from Irish waters.

RATIONALE: In recent years, metabolites produced by Pseudovibrio species have gained scientific attention due to their potent antimicrobial activity. Recently, we also have assessed the antibacterial activities of Pseudovibrio sp. W64 isolates against Staphylococcus aureus, where only the dominant tropodithietic acid (TDA) was identified. However, characterisation of other metabolites is necessary as these metabolites may also serve as potent antimicrobial agents. METHODS: Liquid chromatography/tandem mass spectrometry (LC/MS/MS), aided by accurate mass measurements, was employed to screen and characterise a range of metabolites produced by Pseudovibrio sp. W64 via assessment of ethyl acetate fractions generated from bacterial cultures. RESULTS: Thirteen metabolites unique to the bacterial culture were detected and their chemical structures were assigned by MS/MS and accurate mass measurements. Among the thirteen metabolites, a methyl ester of TDA, a number of cholic acid derivatives, and amino diols and triols were characterised. CONCLUSIONS: Pseudovibrio sp. W64 produces methylated TDA in addition to TDA, and metabolises lipids and amino acids in the cell-culture medium. To the best of our knowledge, this is the first report of methylated TDA, cholic acid and its various analogs, and sphinganine being detected in this Pseudovibrio strain. The data generated may help to better understand the biochemical processes and metabolism of bacterial strains towards discovery of antimicrobial agents from marine sources.

Facile derivatization of ultratrace carboxylic acids in saliva for quantification by HPLC-MS/MS.

It remains an issue to directly quantify trace biologically important carboxyl compounds in body fluids. Herein we propose an innovative method to determine α-lipoic acid, 2-(ß-carboxyethyl)-6-hydroxy-2,7,8-trimethylchroman, prostaglandin E2, cholic acid, and chenodeoxycholic acid in saliva. The method consists of two successive steps: fast and direct labeling of the target analytes with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide followed by ultrahigh-performance liquid chromatography-tandem mass spectrometry analysis. The method exhibited a wide linear range from 2.5 to 2500 pg/mL, with linear coefficients greater than 0.9963 and limits of detection and quantification as low as 0.10 and 0.33 pg/mL, respectively. The method precision was evaluated, with relative standard deviations ranging from 2.12% to 10.63% for intraday assays and from 2.98% to 12.88% for interday assays. The recoveries were measured by our spiking saliva samples with standards at three different levels, and ranged from 72.5% to 98.0%. Real applicability was validated by direct quantification of trace target analytes in human saliva, with simple pretreatment, use of a small sample volume, and a short analysis time. Graphical abstract Sequential steps to extract, label, and determine the ultratrace carboxylic acids in saliva. CDCA chenodeoxycholic acid, γ-CEHC 2-(ß-carboxyethyl)-6-hydroxy-2,7,8-trimethylchroman, α-LA α-lipoic acid, PGE2 prostaglandin E2, UHPLC-MS/MS ultrahigh-performance liquid chromatography-tandem mass spectrometry.

Bile acid analysis in human disorders of bile acid biosynthesis.

Bile acids facilitate the absorption of lipids in the gut, but are also needed to maintain cholesterol homeostasis, induce bile flow, excrete toxic substances and regulate energy metabolism by acting as signaling molecules. Bile acid biosynthesis is a complex process distributed across many cellular organelles and requires at least 17 enzymes in addition to different metabolite transport proteins to synthesize the two primary bile acids, cholic acid and chenodeoxycholic acid. Disorders of bile acid synthesis can present from the neonatal period to adulthood and have very diverse clinical symptoms ranging from cholestatic liver disease to neuropsychiatric symptoms and spastic paraplegias. This review describes the different bile acid synthesis pathways followed by a summary of the current knowledge on hereditary disorders of human bile acid biosynthesis with a special focus on diagnostic bile acid profiling using mass spectrometry.

Profiling of bile acids in bovine follicular fluid by fused-core-LC-MS/MS.

Bile acids (BAs) are present in follicular fluid (FF) from humans and cattle. This fact has triggered an interest on the role BAs might play in folliculogenesis and their possible association with fertility. To achieve a better understanding about this subject, new methods are needed to provide reliable information about concentrations of the most important BAs in FF. In this context, liquid chromatography-tandem mass spectrometry (LC-MS/MS) offers high specificity with a relatively simple sample workup. We developed and validated a new assay for the quick profiling of the 9 most abundant BAs in follicular fluid from cattle. The method uses 200µl of FF and can quantify cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA) and their glycine (G) and taurine (T) conjugates. Lithocholic acid (LCA), its conjugates GLCA and TLCA, and sulfated forms, were present in some samples, but their concentration was low compared to other BAs (in average, below 60ng/ml for LCA, GLCA or TLCA and below 20ng/ml for their corresponding sulfates). Method performance was studied at three quality controls for each compound in consonance with their physiological concentration. Excellent linearity and recovery were found for all compounds at every control level. Intra-day and between-day precisions (%CV) and accuracies (relative errors) were below 15% for all the compounds. Matrix effects were negligible for most of the analytes. Samples undergoing freeze-thaw showed no degradation of their BAs. The method makes use of a fused-core phenyl column coupled to a triple quadrupole tandem mass spectrometer to achieve chromatographic separation within 5min. We quantified BAs grouped in four different follicle sizes (3-5mm, 6-8mm, 9-14mm, >15mm), obtaining a similar relative BA profile for all the sizes, with CA always in higher concentration, ranging between 1600 and 18000ng/ml, approximately, followed by its conjugate glycocholic acid, GCA, which ranged between 800 and 9000ng/ml. The highest concentration in CA, DCA or CDCA was always detected in FF stemming from follicles of 6-8mm. To our knowledge, this is the first report in which BAs subspecies have been detected and quantified in bovine follicular fluid.

Metabolomic Characterizations of Liver Injury Caused by Acute Arsenic Toxicity in Zebrafish.

Arsenic is one of the most common metalloid contaminants in groundwater and it has both acute and chronic toxicity affecting multiple organs. Details of the mechanism of arsenic toxicity are still lacking and profile studies at metabolic level are very limited. Using gas chromatography coupled with mass spectroscopy (GC/MS), we first generated metabolomic profiles from the livers of arsenic-treated zebrafish and identified 34 significantly altered metabolite peaks as potential markers, including four prominent ones: cholic acid, glycylglycine, glycine and hypotaurine. Combined results from GC/MS, histological examination and pathway analyses suggested a series of alterations, including apoptosis, glycogenolysis, changes in amino acid metabolism and fatty acid composition, accumulation of bile acids and fats, and disturbance in glycolysis related energy metabolism. The alterations in glycolysis partially resemble Warburg effect commonly observed in many cancer cells. However, cellular damages were not reflected in two conventional liver function tests performed, Bilirubin assay and alanine aminotransferase (ALT) assay, probably because the short arsenate exposure was insufficient to induce detectable damage. This study demonstrated that metabolic changes could reflect mild liver impairments induced by arsenic exposure, which underscored their potential in reporting early liver injury.

Effects of Two Traditional Chinese Cooking Oils, Canola and Pork, on pH and Cholic Acid Content of Faeces and Colon Tumorigenesis in Kunming Mice.

Faecal pH and cholate are two important factors that can affect colon tumorigenesis, and can be modified by diet. In this study, the effects of two Chinese traditional cooking oils (pork oil and canola/rapeseed oil) on the pH and the cholic acid content in feces, in addition to colon tumorigenesis, were studied in mice. Kunming mice were randomized into various groups; negative control group (NCG), azoxymethane control group (ACG), pork oil group (POG), and canola oil Ggroup (COG). Mice in the ACG were fed a basic rodent chow; mice in POG and COG were given 10% cooking oil rodent chow with the respective oil type. All mice were given four weekly AOM (azoxymethane) i.p. injections (10 mg/kg). The pH and cholic acid of the feces were examined every two weeks. Colon tumors, aberrant crypt foci and organ weights were examined 32 weeks following the final AOM injection. The results showed that canola oil significantly decreased faecal pH in female mice (P<0.05), but had no influence on feces pH in male mice (P>0.05). Pork oil significantly increased the feces pH in both male and female mice (P<0.05). No significant change was found in feces cholic acid content when mice were fed 10% pork oil or canola oil compared with the ACG. Although Kunming mice were not susceptible to AOM-induced tumorigenesis in terms of colon tumor incidence, pork oil significantly increased the ACF number in male mice. Canola oil showed no influence on ACF in either male or female mice. Our results indicate that cooking oil effects faecal pH, but does not affect the faecal cholic acid content and thus AOM-induced colon neoplastic ACF is modified by dietary fat.

Design of ß-CD-surfactant complex-coated liquid crystal droplets for the detection of cholic acid via competitive host-guest recognition.

ß-CD-C14TAB complex-coated 5CB droplets are designed by the adsorption of ß-CD-C14TAB complexes at the 5CB/aqueous interface. We show that the 5CB droplets can be used as an optical probe for the selective detection of cholic acid in aqueous solution containing uric acid and urea via competitive host-guest recognition.

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

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

Development of a multiple-bile-ion-sensing membrane electrode.

A multiple-bile-ion-sensing polyvinyl chloride-based membrane electrode capable of monitoring any of the three common bile ions in humans, namely, cholate, deoxycholate, and chenodeoxycholate, was developed and characterized. Compared to single-bile-ion-sensing electrodes, it showed a sub-Nernstian response. All other electrode properties were, however, similar, making this a successful replacement for three individual electrodes. With appropriate conditioning, this electrode could repeatedly change selectivity without losing membrane activity. It was reproducible, was stable for 5 months, had low response time, and could be used to measure critical micelle concentrations. The lower limit of detection was 10 nM. Selectivity coefficients for various anions with respect to bile ions more or less followed the Hoffmeister series. Plots of R ((Nernst equivalent of slope in the presence of primary ion and a fixed amount of interfering ion)/(slope in the presence of only the primary ion)) vs square root of ionic strength for an interfering ion were linear. One major application of this electrode is its use in kinetics. We have tested its ability to monitor continuously changing bile ion concentrations during their interactions with a biocompatible polymer, polyethylene glycol (6000), and determined rate constants.

Method development and validation of six bile acids for regulated bioanalysis: improving selectivity and sensitivity.

BACKGROUND: Quantification of bile acids using LC-MS has previously been very challenging on triple quadrupole MS systems due to the absence of a primary fragment ion for unconjugated bile acids. RESULTS: A LC-high-resolution/accurate mass MS method for the analysis of six bile acids (cholic acid, chenodeoxycholic acid, taurocholic acid, deoxycholic acid, lithocholic acid and ursodeoxycholic acid) was developed and successfully validated. The method includes a single extraction and a single injection with all analytes separated using target-selected ion monitoring (SIM) mode in two periods with a resolution of 70,000 and 140,000, respectively. CONCLUSION: This is the first LC-high-resolution/accurate mass assay fully validated to quantify six bile acids for regulated bioanalysis.

Biomolecular signatures of diabetic wound healing by structural mass spectrometry.

Wound fluid is a complex biological sample containing byproducts associated with the wound repair process. Contemporary techniques, such as immunoblotting and enzyme immunoassays, require extensive sample manipulation and do not permit the simultaneous analysis of multiple classes of biomolecular species. Structural mass spectrometry, implemented as ion mobility-mass spectrometry (IM-MS), comprises two sequential, gas-phase dispersion techniques well suited for the study of complex biological samples because of its ability to separate and simultaneously analyze multiple classes of biomolecules. As a model of diabetic wound healing, poly(vinyl alcohol) sponges were inserted subcutaneously into nondiabetic (control) and streptozotocin-induced diabetic rats to elicit a granulation tissue response and to collect acute wound fluid. Sponges were harvested at days 2 or 5 to capture different stages of the early wound-healing process. Utilizing IM-MS, statistical analysis, and targeted ultraperformance liquid chromatography analysis, biomolecular signatures of diabetic wound healing have been identified. The protein S100-A8 was highly enriched in the wound fluids collected from day 2 diabetic rats. Lysophosphatidylcholine (20:4) and cholic acid also contributed significantly to the differences between diabetic and control groups. This report provides a generalized workflow for wound fluid analysis demonstrated with a diabetic rat model.

Gold-silver-nanoclusters having cholic acid imprinted nanoshell.

Molecular imprinted polymers (MIPs) as a recognition element for sensors are increasingly of interest and MIP-nanoparticles have started to appear in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamido-cysteine (MAC) attached to gold-silver-nanoclusters reminiscent of a self-assembled monolayer and have reconstructed surface shell by synthetic host polymers based on molecular imprinting method for cholic acid recognition. In this method, methacryloylamidohistidine-Pt(II) [MAH-Pt(II)] has used as a new metal-chelating monomer via metal coordination-chelation interactions and cholic acid. Nanoshell sensors with templates give a cavity that is selective for cholic acid. The cholic acid can simultaneously chelate to Pt(II) metal ion and fit into the shape-selective cavity. Thus, the interaction between Pt(II) ion and free coordination spheres has an effect on the binding ability of the gold-silver-nanoclusters nanosensor. The binding affinity of the cholic acid imprinted nanoparticles have investigated by using the Langmuir and Scatchard methods and determined affinity constant (K(affinity)) has found to be 2.73 × 10(4) mol L(-1) and 2.13 × 10(8) mol L(-1), respectively. At the last step of this procedure, cholic acid level in blood serum and urine which belong to a healthy people were determined by the prepared gold-silver-nanoclusters.

Cattle bile but not bear bile or pig bile induces lipid profile changes and fatty liver injury in mice: mediation by cholic acid.

Three types of animal bile preparation, bear bile (BB), cattle bile (CB) and pig bile (PB) differ in bile acid composition and are supposed to exert different pharmacotoxicological actions. Dietary supplementation with CB at 1% (w/w) for 4 weeks decreased triacylglycerol (TAG) level but increased total cholesterol (CHO) level in serum, which were associated with fatty liver injury in mice. The increased levels of cholesterol esters (CE) and monounsaturated fatty acids (MUFA) in the serum and liver were observed in the mice fed the CB-supplemented diet. Lipid abnormalities and fatty liver injury observed in the mice fed the CB diet were not induced by the supplementation with BB and PB. The supplementation with cholic acid (CA), the most abundant bile acid in CB, could induce lipid abnormalities and fatty liver injury, which were indistinguishable from those induced by CB supplementation. CB and CA supplementation induced similar changes in the expression levels of mRNAs in the liver. Thus, CB induced lipid abnormalities and fatty liver injury, which can be attributed to the actions of CA contained in CB. The inabilities of BB and PB to induce lipid abnormalities and fatty liver injury are supposed to be due to their limited contents of CA.

Association between low colonic short-chain fatty acids and high bile acids in high colon cancer risk populations.

We propose that the influence of diet on colon cancer risk is mediated by the microbiota. To investigate how dietary fat influences risk, we compared the colonic contents of 12 adult high-risk African Americans (AAs) and 10 Caucasian Americans (CAs) who consumed a high-fat diet (123 ± 11 g/d and 129 ± 17 g/d, respectively) to 13 native Africans (NAs) who subsisted on a low-fat (38 ± 3.0 g/d) diet, all aged 50-60 yr. The colonic bile acids were measured by LC-MS and the short-chain fatty acids (SCFAs) by GC. The chief secondary colonic bile acids, deoxycholic acid and lithocholic acid, were correlated with fat intake and similar between AAs and CAs, but 3-4 times higher than in AAs (p < 0.05). The major SCFAs were lower in AAs (p < 0.001) and CAs (p < 0.001) compared to AAs, but conversely, the branched chain fatty acids (BFCA) were higher. Our results suggest that the higher risk of colon cancer in Americans may be partly explained by their high-fat and high-protein, low complex carbohydrate diet, which produces colonic residues that promote microbes to produce potentially carcinogenic secondary bile acids and less antineoplastic SCFAs. The role of BCFA in colonic carcinogenesis deserves further study.

The necessity for the coating of perfluorodecalin-filled poly(lactide-co-glycolide) microcapsules in the presence of physiological cholate concentrations: Tetronic-908 as an exemplary polymeric surfactant.

Recently, we demonstrated that biodegradable poly(lactide-co-glycolide) (PLGA) micro- and nanocapsules with a liquid content of perfluorodecalin are principally useful for the development of artificial oxygen carriers. In order to solve a decisive and well-known problem with PLGA microcapsules, i.e. the spontaneous agglomeration of the capsules after depletion of the emulsifying agent (i.e. cholate), coating with the ABA block copolymer, Tetronic-908 was studied. After Tetronic-908 treatment at concentrations that were harmless to cultured cells, the clustering of the microcapsules was prevented, the adsorption of opsonins was decreased and the attachment to cells was inhibited, but the oxygen transport capacity of PLGA microcapsules was even increased. The present data clearly show that perfluorodecalin-filled PLGA microcapsules must be coated before decreasing the emulsifying agent cholate to physiological concentrations, in order to develop a solution that has the capabilities to function as a potential artificial oxygen carrier suspension.