Cholesterol (thermodynamic) activity determinations in bile salt-lecithin-cholesterol systems and cholesterol-rich liquid crystalline mesophase formation.
Cholesterol (thermodynamic) activity determinations in bile salt-lecithin-cholesterol systems and cholesterol-rich liquid crystalline mesophase formation.
复制标题
胆汁盐-卵磷脂-胆固醇系统中的胆固醇（热力学）活性测定和富含胆固醇的液晶中间相形成。
DOI：
10.1023/a:1015811807438
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发表时间：
1992
影响因子：
3.7
通讯作者：
Mazer,NA
中科院分区：
文献类型：
--
作者：
Jain,UK;Higuchi,WI;Liu,CL;Lee,PH;Mazer,NA
Previousin vitrostudies have shown that tauroursodeoxycholate (TUDC)–lecithin (L) micellar solutions solubilize cholesterol (Ch) poorly compared to its 7α-epimer, taurochenodeoxycholate (TCDC). However, in clinical studies ursodeoxycholic acid (UDC) has been found to be as effective as chenodeoxycholic acid (CDC) in Ch gallstone dissolution, and it has been suggested that, during UDC therapy, liquid crystalline mesophase formation may be involved in enhancing micellar Ch dissolution and dispersion. The purpose of the present study was to investigate whether measurements of the Ch thermodynamic activity (AT) would provide new insights into the problem of Ch solubilization and mesophase formation in bile salt–lecithin–Ch systems. Using the silicone polymer uptake method developed in this laboratory,ATwas measured as a function of Ch concentration in the TUDC-L-Ch and TCDC-L-Ch model bile systems. In the TCDC systems Henry's law was obeyed almost up to unit activity (i.e.,ATwas proportional to Ch concentration almost up toAT= 1.0). However, in many of the TUDC-containing systems negative deviations from Henry's law were observed well below unit activity and these systems became visibly turbid before saturation with respect to cholesterol monohydrate (ChM) was reached. The effects of varying the TCDC/TUDC ratio upon theATbehavior were also studied. With increasing TCDC/TUDC ratio, the onset of mesophase formation was shifted to higherATvalues.ATmeasurements were also conducted in BS-L-Ch mixtures simulating biles of patients undergoing UDC therapy. The results obtained suggest that mesophase formation may not always occur in biles of patients undergoing UDC therapy. However, it is suggested that, even in cases where mesophase formation may not take place in the bulk solution phase, mesophase formation may occur on ChM crystallite surfaces during micellar dissolution.
