CHARACTERIZATION OF CRYSTALLIZATION PATHWAYS DURING CHOLESTEROL PRECIPITATION FROM HUMAN GALLBLADDER BILES - IDENTICAL PATHWAYS TO CORRESPONDING MODEL BILES WITH 3 PREDOMINATING SEQUENCES

In model biles, five crystallization sequences are present as function s of bile salt/lecithin (egg yolk) ratio and their positions on phase diagrams are influenced by bile salt hydrophobicity, temperature, and total lipid concentration (D. Q-H. Wang and M. C. Carey. J. Lipid Res. 1996.37: 606-630). To determine whether the same pathways occur ex vi vo during cholesterol precipitation from human gallbladder biles, we e xamined 22 cholesterol gallstone (CSI = 1.56 +/- 0.26), 4 pigment gall stone (0.69 +/- 0.06), and 4 control biles (0.85 +/- 0.22) by microsco py and lipid analytic techniques for 30 days. Temperature was varied ( 4-45 degrees C) to move relative compositions into adjacent pathways o r supersaturated zones to test whether the same bile could be forced t o crystallize in different sequences. Sequences in native bile were id entical to those in model systems composed of mixed bile salts-lecithi n-cholesterol mixtures, and three corresponding pathways (B, C, D; op. cit.) were observed at 37 degrees C with increasing lecithin content, we found i) B: plate-like cholesterol monohydrate crystals appeared b efore are-shaped (putatively anhydrous cholesterol) crystals which tra nsformed via helices and tubules into plate-like crystals and no liqui d crystals formed; ii) C:lamellar liquid crystals, typified by birefri ngent multilamellar vesicles, were detected before cholesterol monohyd rate crystals, and subsequently are, helical and tubular crystals appe ared; and iii) D: precipitation of lamellar liquid crystals was follow ed by cholesterol monohydrate crystals and no are crystals were detect ed. Added EDTA prevented calcium bilirubinate formation, but crystalli zation sequences in these biles were identical to those without EDTA. We conclude that i) cholesterol crystallization pathways and sequences in human gallbladder biles are identical to model biles matched for a ppropriate physical-chemical conditions; ii) three of the five sequenc es observed in model biles were found in native bile; and iii) calcium bilirubinates neither promote biliary cholesterol crystallization nor influence crystal growth.