PubMed · 1108286
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L O Standaert. 1975. [Lithogenic bile].. https://pubmed.ncbi.nlm.nih.gov/1108286/
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Cholesterol crystallization in bile is affected by phosphatidylcholine (PtdCho) hydrophobicity. The aim of the present study was to determine whether PtdCho species modulate the metastable-labile limit and equilibrium solubility of cholesterol in the micellar phase of bile, thereby altering the distribution of cholesterol to biliary lipid carriers and thus influencing cholesterol crystallization. Supersaturated model bile (with a cholesterol saturation index of 2.0 and a total lipid concentration of 10 g/dl) was prepared with various PtdCho/(bile salt+PtdCho) ratios (0.1-0.5) using egg yolk or soya bean PtdCho. Subsequently, the following features were determined: metastable-labile limit, equilibrium solubility of cholesterol, metastable zone, and cholesterol crystallization process. Less hydrophobic PtdCho species destabilized bile cholesterol to induce rapid crystallization, because of a broad integrated metastable zone, whereas more hydrophobic species stabilized bile cholesterol with a less integrated metastable zone and thus retarded cholesterol crystallization. Cholesterol crystallization was accelerated by a decrease in the PtdCho/(bile salt+PtdCho) ratio, whereas the final nucleated crystal mass was increased by an increase in this ratio. With decreasing hydrophobicity of the PtdCho species, the intermixed micellar/vesicular concentration of bile salts decreased in association with less formation of vesicles and increased formation of micelles, and a variety of crystal forms were detected. In conclusion, PtdCho species directly influenced the cholesterol crystallization process in model bile by remodelling the bile mesophase, and also had an indirect influence by altering the balance between bile salt micelles and vesicles.
At present, specific evidence regarding the molecular mechanisms of neonatal cholestasis is limited. The recent explosion in the understanding of the molecular physiology of bile formation has been fueled by the discovery of several genes that are involved in familial cholestasis. The ever-growing understanding of the functional immaturity of the neonatal liver is sure to be enhanced by the study of the ontogeny of important hepatobiliary transporters as they are discovered. The understanding of the functional differences between the immature and mature liver is key to the understanding of neonatal cholestasis.
AIMS: The aim of this study is to clarify the effect of Tween 80 on bile tolerance of lactococci. METHODS AND RESULTS: Four out of the six strains of lactococci could grow in broth containing 0.3% bile in the presence of 1% Tween 80, but grew slightly or not at all in the absence of Tween 80. Growing with Tween 80 altered the fatty acid composition of all three strains tested, but it is not clear which fatty acid influences bile tolerance. Material that absorbed light at 260 nm leaked from the cells tested with bile, but the leakage was decreased by addition of 1% Tween 80. Coincidentally, the decrease in the cell count by exposure to bile was suppressed by addition of Tween 80. CONCLUSIONS: Tween 80 enhances bile tolerance of some strains of lactococci. SIGNIFICANCE AND IMPACT OF THE STUDY: It is clarified that Tween 80 in the broth contributes to the bile tolerance of lactococci by reducing the cellular leakage caused by bile.