Differential patterns of lipid-protein association in fast and slow cholesterol nucleating human gallbladder biles: implications for cholesterol nucleation from biliary lipid carriers

Lamellar bodies coexist with vesicles and micelles in human gallbladder bile. Ursodeoxycholic acid prevents cholesterol crystal nucleation by increasing biliary lamellae

“…The cholesterol saturation was computed using Carey's critical tables (28), after correction for UDCA content. Cholesterol crystal observation time (nucleation time) was essentially determined according to Holan et al (29), with slight modifications (20), incubating isotropic bile specimens prepared by ultracentrifugation, as specified above. This was considered as the earliest detection of a typical (plate-like) cholesterol monohydrate crystal at 1600 X magnification.…”

“…Freshly obtained native biles and equilibrated model biles were submitted to ultracentrifugation to generate isotropic crystal-free samples, as previously described (20). In brief, an aliquot (4.5 ml) of bile was ultracentrifuged for 2 h at 150 000 g at 37°C using a SW 50.1 rotor and a Beckman L8-70M ultracentrifuge (Fullertone, CA, USA).…”

“…Two 0.4 ml aliquots of each sample were simultaneously incubated for 2 h, one with 0.05 ,Ki of sn-1-palmitoyl, sn-2[14C]-linoleoyl lecithin, and the other with 0.5 ,&i of [3H]-cholesterol, immediately prior to gel-chromatography For this purpose, the appropriate amounts of the radiolabeled compounds were dried under nitrogen in the incubation vials. Aliquots of 200 ~1 were simultaneously applied to two separate prepacked Superose-6 columns (one column was used for each label), equilibrated with a 20 mM Tris-HCl (pH 8.0), 140 mM NaCl, 3.0 mM NaN3, 7 mM sodium taurocholate buffer (20). The buffer was run at a flow rate of 0.5 ml/min, using two P-500 pumps (Pharmacia, Uppsala, Sweden).…”

“…Cholesterol and lecithin were coeluted in four different zones: #I (fractions 7-9), corresponding to the void volume, >3000 kDa). Lipids were eluted in this zone only in very dilute bile samples; #II (fractions 12-15), usually a shoulder corresponding to a molecular size of loo-220 kDa; #III (fractions 16 17) a sharp peak corresponding to 50-100 kDa; #IV (fractions [18][19][20][21][22] another broad peak corresponding to 6-50 kDa. The elution pattern of the isotropic phase obtained after ultracentrifugation of the same bile (Fig.…”

Structural Mechanisms of Bile Salt-Induced Growth of Small Unilamellar Cholesterol−Lecithin Vesicles

“…These effects may explain why bile becomes more metastable with increasing total BS/L (Kibe et al, 1985;Harvey et al, 1987). By the same token, amphiphilic proteins can possibly become "secondary" pro-nucleators by either exercising their surfaceactive properties (Ahmed et al, 1994) or acting as transfer carriers that facilitate aqueous diffusion of CH and L monomers (Corradini et al, 1991).…”