PubMed · 6717287
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A J Furth, H Bolton, J Potter, J D Priddle. 1984. Separating detergent from proteins.. https://doi.org/10.1016/s0076-6879(84)04098-2
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Clostridium scindens is a keystone bacterial species in the mammalian gut that, while low in abundance, has a significant impact on bile acid and steroid metabolism. Numerous studies indicate that the two most studied strains of C. scindens (i.e. ATCC 35704 and VPI 12708) are important for a myriad of physiological processes in the host. We focus on both historical and current microbiological and molecular biology work on the Hylemon-Björkhem pathway and the steroid-17,20-desmolase pathway that were first discovered in C. scindens. Our most recent analysis now calls into question whether strains currently defined as C. scindens represent two separate taxonomic groups. Future directions include developing genetic tools to further explore the physiological role of bile acid and steroid metabolism by strains of C. scindens and the causal role of these pathways in host physiology and disease.
BACKGROUND: Retention of caffeine was observed in patients with alcoholic liver cirrhosis and impaired liver function. Cotinine, the major metabolite of nicotine, is transformed by microsomal N-oxidation to secondary metabolites. The aim of this study was to investigate if impaired liver function leads to a retention of cotinine in a similar way to caffeine retention. Furthermure the influence of smoking on cotinine and caffeine plasma levels was studied. METHODS: 91 smokers and 12 nonsmokers with alcoholic liver cirrhosis were subdivided according to their smoking habits. Cotinine plasma levels and fasting caffeine concentrations were measured by a gaschromatographic method. Concentrations of conjugated bile acids were measured by RIA. 10 healthy smokers and 11 nonsmokers were used as a control group. RESULTS: Mean plasma cotinine concentrations found in slight smokers (200 +/- 155 ng/ml), intermediate smokers (384 +/- 223 ng/ml) and heavy smokers (430 +/- 266 ng/ml) with alcoholic liver cirrhosis were significantly higher than in healthy, smoking volunteers with slight, intermediate, and heavy smoking (101 +/- 14; 274 +/- 112; 345 +/- 85 ng/ml) (p <0.01) respectively. In nonsmokers with alcoholic liver cirrhosis plasma cotinine (44 +/- 25 ng/ml) was significantly elevated compared to healthy nonsmokers (27 +/- 19 ng/ml) (p <0.01). - Fasting caffeine plasma levels in patients with alcoholic liver cirrhosis (4.00 +/- 5. 20 microg/ml) were significantly higher than in healthy volunteers (0.91 +/- 0.42 microg/ml) (p <0.01). A decrease of plasma levels was observed in correlation to the amount of smoking in patients with alcoholic cirrhosis (slight smokers: 7.67 +/- 8.54 microg/ml, intermediate smokers: 3.35 +/- 2.91 microg/ml and heavy smokers: 2. 48 +/- 2.68 microg/ml). Conjugated bile acids were elevated in patients with alcoholic liver cirrhosis to 32,56 +/- 38,24 mmol/l. CONCLUSIONS: Increased cotinine plasma levels in smokers and nonsmokers with alcoholic liver cirrhosis demonstrate a cotinine retention in patients with impaired liver function. The inducing effect of smoking is shown by a decrease of fasting caffeine plasma concentrations.
Bifunctional peptidylglycine alpha-amidating monooxygenase (PAM) catalyzes the copper-, ascorbate-, and O(2)-dependent cleavage of C-terminal glycine-extended peptides and N-acylglycines to the corresponding amides and glyoxylate. The alpha-amidated peptides and the long-chain acylamides are hormones in humans and other mammals. Bile acid glycine conjugates are also substrates for PAM leading to the formation of bile acid amides. The (V(MAX)/K(m))(app) values for the bile acid glycine conjugates are comparable to other known PAM substrates. The highest (V(MAX)/K(m))(app) value, 3.1 +/- 0.12 x 10(5) M(-1) s(-1) for 3-sulfolithocholylglycine, is 6.7-fold higher than that for d-Tyr-Val-Gly, a representative peptide substrate. The time course for O(2) consumption and glyoxylate production indicates that bile acid glycine conjugate amidation is a two-step reaction. The bile acid glycine conjugate is first converted to an N-bile acyl-alpha-hydroxyglycine intermediate which is ultimately dealkylated to the bile acid amide and glyoxylate. The enzymatically produced bile acid amides and the carbinolamide intermediates were characterized by mass spectrometry and two-dimensional (1)H-(13)C heteronuclear multiple quantum coherence NMR.