Interaction of apolipoprotein A-I with lecithin-cholesterol vesicles in the presence of phospholipase C

Identification of cholelithogenic enterohepatic helicobacter species and their role in murine cholesterol gallstone formation

BACKGROUND & AIMS

Helicobacter spp are common inhabitants of the hepatobiliary and gastrointestinal tracts of humans and animals and cause a variety of well-described diseases. Recent epidemiologic results suggest a possible association between enterohepatic Helicobacter spp and cholesterol cholelithiasis, chronic cholecystitis, and gallbladder cancer. To test this, we prospectively investigated the effects of Helicobacter spp infection in cholesterol gallstone pathogenesis in the highly susceptible C57L/J mouse model.

METHODS

Helicobacter spp-free adult male C57L mice were infected with several different enterohepatic Helicobacter spp or left uninfected and fed either a lithogenic diet or standard mouse chow for 8 and 18 weeks. At the conclusion of the study, bile was examined microscopically and diagnostic culture and polymerase chain reaction were performed.

RESULTS

Mice infected with Helicobacter bilis or coinfected with Helicobacter hepaticus and Helicobacter rodentium and fed a lithogenic diet developed cholesterol gallstones at 80% prevalence by 8 weeks compared with approximately 10% in uninfected controls. Monoinfections with H hepaticus , Helicobacter cinaedi , and H rodentium gave a cholesterol gallstone prevalence of 40%, 30%, and 20%, respectively; the latter 2 groups did not differ significantly from uninfected animals. Neither infected nor uninfected mice fed a chow diet developed cholesterol gallstones.

CONCLUSIONS

These findings, along with prior epidemiologic studies, suggest that Helicobacter spp play a major role in the pathophysiology of cholesterol gallstone formation in mice and perhaps humans.

Temperature and cholesterol composition-dependent behavior of 1-myristoyl-2-[12-[(5-dimethylamino-1-naphthalenesulfonyl)amino]dodecanoyl]-sn-glycero-3-phosphocholine in 1,2-dimyristoyl-sn-glycero-3-phosphocholine membranes

We present a steady-state and time-resolved fluorescence emission spectra analysis of the membrane probe 1-myristoyl-2-[12-[(5-dimethylamino-1-naphthalenesulfonyl)amino]dodecanoyl]-sn-glycero-3-phosphocholine (DANSYL) in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and cholesterol multi-lamellar vesicles (MLV) prepared by modified rapid solvent exchange. We report that the dose-dependent cholesterol-induced blue shifts in the steady-state fluorescence emission spectra observed in DMPC MLV are due to complex solvent effects that include time-dependent dipolar relaxation and the formation of internal charge transfer (ICT) states. A key finding of this investigation is identification of two distinguishable DANSYL populations existing at both shallow and deep locations in the membrane; these two DANSYL populations are evidence of laterally phase-separated domains at cholesterol compositions between X(chol) = 0.30 and 0.60 at 30 degrees C in DMPC MLV.