The long-term objectives of this proposal are to characterize the structure and properties of gallbladder mucin in experimental animals and man, and to elucidate the contribution of this glycoprotein to the pathophysiology of cholesterol and pigment gallstones. To accomplish these objectives we will employ biochemical and biophysical techniques to further define the structure of mucin, and will study nucleation and stone formation in vitro and in vivo.
Our specific aims are as follows: 1. To determine the subunit structure of gallbladder mucin, particularly the contribution of disulfide bridges and hydrophobic interactions to polymer formation and gelation. Viscometric and quasielastic light scattering spectroscopy will be used to study gel formation of native mucin in solution. 2. To compare the ability of native and modified mucins from animals and human gallbladders to nucleate cholesterol monohydrate in bile. These studies will help to elucidate one mechanism of gallstone nucleation. 3. To test the ability of mucolytic agents to enhance gallstone dissolution in cholesterol solvents such as mono-octanoin and bile salts. These agents will be tested in vitro first, then in vivo on human gallstones implanted in gallbladders of experimental animals receiving a lithogenic diet. We also will study the formation and composition of biliary sludge in experimental animals and man, as this material, a precipitate of bilirubin and mucin, is thought to be a precursor of gallstones. These studies have direct relevance to human gallstone disease, and may lead to improved stone dissolution therapy.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK028195-06
Application #
3228658
Study Section
(SSS)
Project Start
1980-07-01
Project End
1989-03-31
Budget Start
1986-04-01
Budget End
1987-03-31
Support Year
6
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Boston University
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02118
Cao, X; Bansil, R; Bhaskar, K R et al. (1999) pH-dependent conformational change of gastric mucin leads to sol-gel transition. Biophys J 76:1250-8
Turner, B S; Bhaskar, K R; Hadzopoulou-Cladaras, M et al. (1999) Cysteine-rich regions of pig gastric mucin contain von willebrand factor and cystine knot domains at the carboxyl terminal(1). Biochim Biophys Acta 1447:77-92
Bhaskar, K R; Turner, B S; Grubman, S A et al. (1998) Dysregulation of proteoglycan production by intrahepatic biliary epithelial cells bearing defective (delta-f508) cystic fibrosis transmembrane conductance regulator. Hepatology 27:7-14
Grubel, P; Bhaskar, K R; Cave, D R et al. (1997) Interaction of an aluminum-magnesium containing antacid and gastric mucus: possible contribution to the cytoprotective function of antacids. Aliment Pharmacol Ther 11:139-45
Turner, B S; Bhaskar, K R; Hadzopoulou-Cladaras, M et al. (1995) Isolation and characterization of cDNA clones encoding pig gastric mucin. Biochem J 308 ( Pt 1):89-96
Afdhal, N H; Gong, D; Niu, N et al. (1993) Cholesterol cholelithiasis in the prairie dog: role of mucin and nonmucin glycoproteins. Hepatology 17:693-700
Lamont, J T; Carey, M C (1992) Cholesterol gallstone formation. 2. Pathobiology and pathomechanics. Prog Liver Dis 10:165-91
Carey, M C; Lamont, J T (1992) Cholesterol gallstone formation. 1. Physical-chemistry of bile and biliary lipid secretion. Prog Liver Dis 10:139-63
Bhaskar, K R; Gong, D H; Bansil, R et al. (1991) Profound increase in viscosity and aggregation of pig gastric mucin at low pH. Am J Physiol 261:G827-32
O'Leary, D P; Murray, F E; Turner, B S et al. (1991) Bile salts stimulate glycoprotein release by guinea pig gallbladder in vitro. Hepatology 13:957-61

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