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García-Rodríguez A, Moreno-Olivas F, Marcos R, Tako E, Marques CNH, Mahler GJ. The Role of Metal Oxide Nanoparticles, Escherichia coli, and Lactobacillus rhamnosus on Small Intestinal Enzyme Activity. ENVIRONMENTAL SCIENCE. NANO 2020; 7:3940-3964. [PMID: 33815806 PMCID: PMC8011031 DOI: 10.1039/d0en01001d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Engineered nanomaterials (ENMs) have become common in the food industry, which motivates the need to evaluate ENM effects on human health. Gastrointestinal (GI) in vitro models (e.g. Caco-2, Caco-2/HT29-MTX) have been used in nanotoxicology research. However, the human gut environment is composed of both human cells and the gut microbiota. The goal of this study is to increase the complexity of the Caco-2/HT29-MTX in vitro model by co-culturing human cells with the Gram-positive, commensal Lactobacillus rhamnosus or the Gram-negative, opportunistic Escherichia coli; with the hypothesis that the presence of bacteria would ameliorate the effects of exposure to metal oxide nanoparticles (NPs) such as iron oxide (Fe2O3), silicone dioxide (SiO2), titanium dioxide (TiO2), or zinc oxide (ZnO). To understand this relationship, Caco-2/HT29-MTX cell barriers were acutely co-exposed (4 hours) to bacteria and/or NPs (pristine or in vitro digested). The activity of the brush border membrane (BBM) enzymes intestinal alkaline phosphatase (IAP), aminopeptidase-N (APN), sucrase isomaltase (SI) and the basolateral membrane enzyme (BLM) Na+/K+ ATPase were assessed. Findings show that (i) the human digestion process alters the physicochemical properties of NPs, (ii) large agglomerates of NPs remain entrapped on the apical side of the intestinal barrier, which (iii) affects the activity of BBM enzymes. Interestingly, some NPs effects were attenuated in the presence of either bacterial strains. Confocal microscopy detected bacteria-NPs interactions, which may impede the NP-intestinal cell contact. These results highlight the importance of improving in vitro models to closely mimic the complexities of the human body.
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Affiliation(s)
- Alba García-Rodríguez
- Department of Biomedical Engineering, Binghamton University, Binghamton, NY, 13902, USA
- Binghamton Biofilm Research Center, Binghamton University, Binghamton, NY, 13902, USA
- Department of Biological Sciences, Binghamton University, Binghamton, NY, 1302, USA
- Department of Genetics and Microbiology, Faculty of Bioscience, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain
| | - Fabiola Moreno-Olivas
- Department of Biomedical Engineering, Binghamton University, Binghamton, NY, 13902, USA
- Binghamton Biofilm Research Center, Binghamton University, Binghamton, NY, 13902, USA
| | - Ricard Marcos
- Department of Genetics and Microbiology, Faculty of Bioscience, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Barcelona, 08193, Spain
| | - Elad Tako
- Department of Food Science, Cornell University, Stocking Hall, Ithaca, NY, 14853-7201, USA
| | - Cláudia N. H. Marques
- Binghamton Biofilm Research Center, Binghamton University, Binghamton, NY, 13902, USA
- Department of Biological Sciences, Binghamton University, Binghamton, NY, 1302, USA
| | - Gretchen J. Mahler
- Department of Biomedical Engineering, Binghamton University, Binghamton, NY, 13902, USA
- Binghamton Biofilm Research Center, Binghamton University, Binghamton, NY, 13902, USA
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Portincasa P, van Erpecum KJ, Di Ciaula A, Wang DQH. The physical presence of gallstone modulates ex vivo cholesterol crystallization pathways of human bile. Gastroenterol Rep (Oxf) 2019; 7:32-41. [PMID: 30792864 PMCID: PMC6375352 DOI: 10.1093/gastro/goy044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 08/15/2018] [Accepted: 08/28/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Cholesterol crystallization is an essential step toward gallstone formation. Although model bile studies showed that competition occurs between the gallstone surface and the surrounding aqueous phase for cholesterol molecules available for crystallization, this has not been investigated in human bile. METHODS Fresh gallbladder bile was obtained during laparoscopic cholecystectomy from 13 patients with cholesterol (n = 10) or pigment (n = 3) stones. Small cholesterol gallstones were collected from another two patients. Both native and ultrafiltered bile with or without added gallstones was analysed by polarized light microscopy for the presence of arc-like and needle-like anhydrous cholesterol crystals and classic cholesterol monohydrate crystals. Weight of the added stones was evaluated before and after 21 days of bile incubation. RESULTS In unfiltered bile, the presence of stones was associated with a trend towards less anhydrous cholesterol crystals, but significantly more aggregated cholesterol monohydrate crystals. In ultrafiltered bile, the presence of stones tended to inhibit the formation of arc-like or needle-like crystals and was associated with significantly greater amounts of both plate-like and aggregated cholesterol monohydrate crystals. After 21 days of the incubation, stone weight was decreased in both unfiltered (-4.5 ± 1.6%, P = 0.046) and ultrafiltered bile (-6.5 ± 1.5%, P = 0.002). Bile from pigment-stone patients was clear in the absence of stones, but showed early appearance of plate-like and aggregated cholesterol monohydrate crystals in all samples to which cholesterol gallstones were added. CONCLUSIONS The physical presence of cholesterol gallstones in both native and filtered bile greatly influences cholesterol crystallization pathways. Whereas cholesterol monohydrate crystals increase, anhydrous cholesterol crystals tend to be inhibited. Detachment of solid cholesterol crystals from the gallstone surface may explain these findings.
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Affiliation(s)
- Piero Portincasa
- Division of Internal Medicine, Department of Biomedical Sciences and Human Oncology, University Medical School, Bari, Italy
- Corresponding author. Division of Internal Medicine, Clinica Medica ‘A. Murri’, Department of Biomedical Sciences and Human Oncology, University Medical School, Policlinico, Piazza Giulio Cesare 11, Bari, 70124, Italy. Tel: +39-80-5478892; Fax: +39-80-5478232;
| | - Karel J van Erpecum
- Department of Gastroenterology, University Medical Center, Utrecht, The Netherlands
| | - Agostino Di Ciaula
- Division of Internal Medicine, Hospital of Bisceglie, ASL BAT, Bisceglie, Italy
| | - David Q -H Wang
- Department of Medicine, Division of Gastroenterology and Liver Diseases, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, NY, USA
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Tang J, Qu F, Tang X, Zhao Q, Wang Y, Zhou Y, Feng J, Lu S, Hou D, Liu Z. Molecular characterization and dietary regulation of aminopeptidase N (APN) in the grass carp (Ctenopharyngodon idella). Gene 2016; 582:77-84. [DOI: 10.1016/j.gene.2016.01.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 12/30/2015] [Accepted: 01/28/2016] [Indexed: 01/18/2023]
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Acidic Shell Proteins of the Mediterranean Fan Mussel Pinna nobilis. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2011; 52:353-95. [PMID: 21877273 DOI: 10.1007/978-3-642-21230-7_13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
In molluscs, the shell secretion process is controlled by a set of extracellular macromolecules collectively called the shell matrix. The shell matrix, which is produced by the mantle epithelial cells during mineralization, is predominantly composed of proteins, glycoproteins, acidic polysaccharides, and chitin that precisely regulate the deposition of calcium carbonate outside the mantle cells. In the present paper, we focus on the shell of Pinna nobilis, the giant Mediterranean fan mussel, usually considered as a model for studying molluscan biomineralization processes. P. nobilis exhibits indeed a nacro-prismatic shell, the outer layer of which is constituted of the so-called "regular simple calcitic prisms," according to Carter and Clark (1985). We review here the microstructural characteristics of the prisms and nacre and the biochemical properties of their associated matrices. In particular, the calcitic prisms of P. nobilis are characterized by a cortege of unusually acidic intraprismatic proteins, while the ones of the nacreous layer seem less acidic. A brief description of the molecular characterization of three acidic proteins, caspartin, calprismin and mucoperlin, is given. In particular, we show that extremely acidic intracrystalline proteins such as caspartin interact with calcium carbonate at different scales, from micrometric to crystal lattice levels.
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Samudrala N, Farook VS, Dodd GD, Puppala S, Schneider J, Fowler S, Granato R, Dyer TD, Arya R, Almasy L, Jenkinson CP, Diehl AK, Blangero J, Duggirala R. Autosomal Genome-Wide Linkage Analysis to Identify Loci for Gallbladder Wall Thickness in Mexican Americans. Hum Biol 2008; 80:11-28. [DOI: 10.3378/1534-6617(2008)80[11:aglati]2.0.co;2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Wilhelmi M, Jüngst C, Mock M, Meyer G, Zündt B, Del Pozo R, Jüngst D. Effect of gallbladder mucin on the crystallization of cholesterol in bile. Eur J Gastroenterol Hepatol 2004; 16:1301-7. [PMID: 15618836 DOI: 10.1097/00042737-200412000-00011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES Mucin is supposed to accelerate the crystallization of cholesterol in model bile while studies in native human gallbladder bile revealed conflicting results. METHODS Therefore, we determined the relation of mucin concentration and cholesterol crystal observation time in gallbladder bile of 73 patients with cholesterol and mixed and 21 patients with pigment stones. In addition, bile samples of 20 patients with cholesterol gallstones were supplemented with either 0 (control) or 0.5-4.0 mg/ml purified bovine mucin or human mucin isolated from gallbladder bile, to study the effect of variable mucin concentrations on the crystallization of cholesterol. RESULTS Rapid nucleating biles (</= 4 days, n = 59) showed higher mucin concentrations (0.73 +/- 0.1 mg/ml vs 0.43 +/- 0.07 mg/ml) than biles with longer (> 4 days, n = 35) cholesterol crystal observation times (P < 0.05), but no correlation between mucin concentration and cholesterol crystal observation time was observed. Supplementation experiments with bovine purified mucin (up to 4.0 mg/ml) showed no significant effect on the total amount of newly formed cholesterol crystals within 21 days. However, higher amounts of newly formed cholesterol crystals were seen in bile samples supplemented with human mucin in comparison to negative controls. CONCLUSIONS Our results demonstrate a dose-dependent effect of human but not of bovine gallbladder mucin on the formation of cholesterol monohydrate crystals in gallbladder bile of patients with cholesterol stones. Therefore, studies of cholesterol crystallization in model bile systems may be valuable but should always be confirmed in native gallbladder bile as the more physiological effector system.
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Affiliation(s)
- Martin Wilhelmi
- Departments of aMedicine II and bSurgery, Klinikum Grosshadern, Ludwig Maximilians-University Munich, Germany
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Dauphin Y. Soluble organic matrices of the calcitic prismatic shell layers of two Pteriomorphid bivalves. Pinna nobilis and Pinctada margaritifera. J Biol Chem 2003; 278:15168-77. [PMID: 12576478 DOI: 10.1074/jbc.m204375200] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The calcitic prisms of the shells of two bivalves, Pinna and Pinctada, are considered simple prisms according to some morphological and mineralogical characteristics. Scanning electron microscopic and atomic force microscopic studies show that the microstructures and nanostructures of these two shells are different. Pinna prisms are monocrystalline, whereas Pinctada prisms are not. Moreover, intraprismatic membranes are present only in the Pinctada prisms. The soluble organic matrices extracted from these prisms are acidic, but their bulk compositions differ. Ultraviolet and infrared spectrometries, fluorescence, high pressure liquid chromatography, and electrophoresis show that the sugar-protein ratios and the molecular weights are different. Sulfur is mainly associated with acidic sulfated sugars, not with amino acids, and the role of acidic sulfated sugars is still underestimated. Thus, the simple prism concept is not a relevant model for the biomineralization processes in the calcitic prismatic layer of mollusk shells.
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Affiliation(s)
- Yannicke Dauphin
- Laboratoire de Paléontologie, FRE 2566, Université Paris XI-Orsay, F-91405 Orsay, France.
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van Wijland MJ, de Waart DR, Groen AK. Biliary anionic peptide fraction/calcium binding protein inhibits apolipoprotein A-I-mediated cholesterol efflux from cultured cells. Biochem Biophys Res Commun 2001; 287:1-4. [PMID: 11549244 DOI: 10.1006/bbrc.2001.5542] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ABC transporter ABCA1 has been implicated to control cholesterol efflux in a variety of cell types including macrophages, fibroblasts, and intestinal epithelial cells. In this study we have investigated whether the 6-kD protein anionic peptide fraction/calcium binding protein (APF/CBP) which has homology to apolipoprotein AI may regulate efflux mediated by lipoproteins. APF/CBP was purified from T-tube bile by ultracentrifugation and preparative reversed phase HPLC. Cholesterol efflux to a variety of acceptors was determined using cultured fibroblasts from controls and patients with Tangiers disease. APF/CBP (0.1 to 2.4 microg/ml) inhibited ApoA-1 (2 microg/ml) mediated cholesterol efflux from normal fibroblasts in a dose dependent manner but had no effect on aspecific efflux to methyl-beta-cyclodextrin or phosphatidylcholine liposomes. In ABCA1 deficient fibroblasts no effect of APF/CBP on efflux was seen. We conclude that APF/CBP specifically interferes with ApoA-I mediated cholesterol trafficking. We hypothesize that competitive binding to ABCA1 may explain the decreased ApoA-I mediated efflux from fibroblasts.
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Affiliation(s)
- M J van Wijland
- Laboratory of Experimental Hepatology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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Lammert F, Südfeld S, Busch N, Matern S. Cholesterol crystal binding of biliary immuno-globulin A: visualization by fluorescence light microscopy. World J Gastroenterol 2001; 7:198-202. [PMID: 11819760 PMCID: PMC4723522 DOI: 10.3748/wjg.v7.i2.198] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To assess potential contributions of biliary IgA for crystal agglomeration into gallstones, we visualized cholesterol crystal binding of biliary IgA.
METHODS: Crystal binding biliary proteins were extracted from human gallbladder bile using lectin affinity chromatography. Biliary IgA was isolated from the bound protein fraction by immunoaffinity chromatography. Pure cholesterol monohydrate crystals were incubated with biliary IgA and fluoresceine isothiocyanate (FITC)conjugated anti IgA at 37 °C. Samples were examined under polarizing and fluorescence light microscopy with digital image processing.
RESULTS: Binding of biliary IgA to cholesterol monohydrate crystals could be visualized with FITC conjugated anti IgA antibodies. Peak fluorescence occurred at crystal edges and dislocations. Controls without biliary IgA or with biliary IgG showed no significant fluorescence.
CONCLUSION: Fluorescence light microscopy provided evidence for cholesterol crystal binding of biliary IgA. Cholesterol crystal binding proteins like IgA might be important mediators of crystal agglomeration and growth of cholesterol gallstones by modifying the evolving crystal structures in vivo.
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Affiliation(s)
- F Lammert
- Department of Medicine III, RWTH Aachen, Pauwelsstra betae 30, 52057 Aachen,Germany
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de la Porte PL, Lafont H, Domingo N, Meyer G, Müller I, Zündt B, Jüngst D. Composition and immunofluorescence studies of biliary "sludge" in patients with cholesterol or mixed gallstones. J Hepatol 2000; 33:352-60. [PMID: 11019989 DOI: 10.1016/s0168-8278(00)80269-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Gallbladder bile from patients with cholesterol or mixed gallstones frequently contains biliary "sludge", a suspension of cholesterol monohydrate crystals and pigment granules embedded in mucin and proteins. The composition of biliary "sludge" and the preferential localization of mucin and proteins could be an indicator for its potential role in gallstone formation. METHODS Ultracentrifugation (100000 g/l h) was used to precipitate "sludge" from bile, and the concentration difference of its main components between native bile and ultracentrifuged bile samples was calculated. After purification of the sediment, immunolocalization was performed for the detection of mucin, IgA, albumin, aminopeptidase, and anionic polypeptide fraction using polyclonal and monoclonal antibodies. RESULTS The amount of sludge in gallbladder bile was 4.26 mg/ml-0.78 (mean+/-SEM) in patients with cholesterol and 2.51 mg/ml+/-0.39 in patients with mixed stones and cholesterol was the main component (48.9+/-4.6% and 44.4+/-7.1%). The sediment appeared as a mixture of vesicular aggregates and pigment particles which were linked by a gel matrix of mucin containing cholesterol crystals. While anionic polypeptide fraction and aminopeptidase were associated to pigments, IgA was uniformly spread in the crystalline parts of "core-like" structures, and albumin, when it was present, appeared as randomly located small spots. CONCLUSIONS Our study demonstrates that the cholesterol content and the distribution pattern of mucin and different proteins is similar in the sediments of biliary "sludge" to that previously shown in cholesterol and mixed gallstones. This suggests that biliary "sludge" represents an early stage of gallstone formation in these patients.
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Affiliation(s)
- P L de la Porte
- INSERM Unite 476, Nutrition Humaine et Lipides, Marseille, France
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Marin F, Corstjens P, de Gaulejac B, de Vrind-De Jong E, Westbroek P. Mucins and molluscan calcification. Molecular characterization of mucoperlin, a novel mucin-like protein from the nacreous shell layer of the fan mussel Pinna nobilis (Bivalvia, pteriomorphia). J Biol Chem 2000; 275:20667-75. [PMID: 10770949 DOI: 10.1074/jbc.m003006200] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A cDNA expression library constructed from mantle tissue mRNA of the Mediterranean fan mussel Pinna nobilis was screened with antibodies raised against the acetic acid-soluble shell matrix of the same species. This resulted in the isolation of a 2138-base pair cDNA, containing 13 tandem repeats of 93 base pairs. The deduced protein has a molecular mass of 66.7 kDa and a isoelectric point of 4.8. This protein, which is enriched in serine and proline residues, was overexpressed, purified, and used for producing polyclonal antibodies. Immunological in situ and in vitro tests showed that the protein is localized in the nacreous aragonitic layer of P. nobilis, but not in the calcitic prisms. Because this protein of the nacre of P. nobilis exhibits some mucin-like characteristics, we propose the name mucoperlin. This is the first paper reporting the cloning of a molluscan mucin and the first molecular evidence for the involvement of a mucin in molluscan calcification. This finding corroborates our previous hypothesis that some of the proteinaceous constituents of the molluscan shell matrix would derive from mucins, common to many metazoan lineages of the late Precambrian (Marin, F., Smith, M., Isa, Y., Muyzer, G. and Westbroek, P. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 1554-1559). The adaptation of an ancestral mucin to a new function, the regulation of the mineralization process, may be one of the molecular events, among others, that would explain the simultaneous emergence of organized calcification in many metazoan lineages during the Cambrian explosion.
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Affiliation(s)
- F Marin
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
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Duggirala R, Mitchell BD, Blangero J, Stern MP. Genetic determinants of variation in gallbladder disease in the Mexican-American population. Genet Epidemiol 2000; 16:191-204. [PMID: 10030401 DOI: 10.1002/(sici)1098-2272(1999)16:2<191::aid-gepi6>3.0.co;2-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Since there have not been any studies that quantify the influence of genetic factors on gallbladder disease (GBD) in humans using information from families, we utilized pedigree data to explore the genetic control of variation in liability to GBD. Using an extension of a variance components approach, we performed genetic analyses of GBD using information from 32 low-income Mexican-American families with two slightly different general models incorporating several sex-specific GBD risk factors. After evaluating the relative magnitudes of the covariate effects from these two models, we identified a parsimonious model including only significant predictors of GBD. According to this model, heritability for GBD was high (h2 = 0.44+/-0.18), after accounting for the significant effects of age, leptin in both sexes, total cholesterol, and HDL cholesterol in males only. We have shown quantitatively that variation in GBD is under strong genetic control. However, there are two major limitations to our findings: (1) since GBD was defined by a self-reported clinical history rather than an ultrasound examination, the prevalence of GBD could have been underestimated; and (2) since our design did not allow for shared environmental effects, our estimate of heritability may have been inflated.
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Affiliation(s)
- R Duggirala
- Department of Medicine, University of Texas Health Science at San Antonio 78284-7873, USA
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van den Berg AA, van Buul JD, Ostrow JD, Groen AK. Measurement of cholesterol gallstone growth in vitro. J Lipid Res 2000. [DOI: 10.1016/s0022-2275(20)32051-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Nunes DP, Afdhal NH, Offner GD. A recombinant bovine gallbladder mucin polypeptide binds biliary lipids and accelerates cholesterol crystal appearance time. Gastroenterology 1999; 116:936-42. [PMID: 10092316 DOI: 10.1016/s0016-5085(99)70077-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND & AIMS Mucin has a central role in the pathogenesis of cholesterol gallstones, in part because of its ability to bind biliary lipids and accelerate cholesterol crystal appearance time. Previous studies have localized these properties to nonglycosylated mucin domains, and we have recently shown that these domains contain a series of 127-amino acid, cysteine-rich repeats. The aim of this study was to express a recombinant mucin polypeptide containing these repeats and investigate its lipid-binding and pronucleating properties. METHODS A recombinant mucin polypeptide was expressed as a glutathione S-transferase fusion protein in Escherichia coli, purified by affinity chromatography, and compared with native bovine gallbladder mucin in lipid-binding and cholesterol crystal appearance time assays. RESULTS The recombinant mucin polypeptide bound a hydrophobic fluorescent probe and cholesterol in a concentration-dependent manner. It accelerated the appearance of cholesterol crystals from lithogenic model bile, an effect that was both time and concentration dependent. CONCLUSIONS The cysteine-rich repeats in the recombinant mucin polypeptide correspond to the protease-sensitive hydrophobic domains identified in earlier biochemical studies. Further delineation of the lipid-binding site(s) in these repeats will provide new insights into the mechanism of cholesterol crystal nucleation and stone growth.
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Affiliation(s)
- D P Nunes
- Section of Gastroenterology, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts 02118, USA
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van den Berg A, van Buul J, Tytgat G, Groen A, Ostrow J. Mucins and calcium phosphate precipitates additively stimulate cholesterol crystallization. J Lipid Res 1998. [DOI: 10.1016/s0022-2275(20)32161-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Konikoff FM, Lechene de la Porte P, Laufer H, Domingo N, Lafont H, Gilat T. Calcium and the anionic polypeptide fraction (APF) have opposing effects on cholesterol crystallization in model bile. J Hepatol 1997; 27:707-15. [PMID: 9365047 DOI: 10.1016/s0168-8278(97)80088-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND/AIMS Cholesterol gallstones contain both calcium and biliary proteins, but their respective roles in gallstone pathogenesis are unknown. We have studied the effects of calcium and a major biliary protein, anionic polypeptide fraction, on the process of cholesterol crystallization in bile. METHODS Anionic polypeptide fraction was purified from human bile. Model bile composed of cholesterol, egg yolk lecithin and sodium taurocholate was prepared in a lipid concentration (18 mM, 37 mM, and 120 mM, respectively) simulating lithogenic human gallbladder bile. The crystallization process was observed by phase contrast light microscopy, and sequential separation of precipitable cholesterol structures by sucrose density gradient ultracentrifugation. RESULTS Addition of calcium, or anionic polypeptide fraction alone, or both together did not influence the crystal observation time of bile (the time which elapsed from initiation of supersaturation to the first appearance of crystals). However, the rate and quantity of cholesterol precipitation and crystal formation were affected by both. Calcium increased in a dose-dependent manner the cholesterol monohydrate crystal mass before apparent equilibrium was reached. This effect was inhibited by anionic polypeptide fraction, which increased the amount of cholesterol within precipitable phospholipid vesicles, and decreased the rate of crystal formation. Fluorescence-labeled anionic polypeptide fraction revealed that anionic polypeptide fraction (with and without calcium) was primarily associated with vesicle aggregates. CONCLUSIONS Our data demonstrate that calcium and anionic polypeptide fraction have opposing effects on the process of cholesterol crystallization and the resultant crystal mass without influencing the crystal observation time of bile. These findings suggest that biliary proteins, in addition to being crystallization effectors by themselves, may further influence cholesterol crystallization and gallstone formation by interacting with calcium and possibly other elements that coexist in bile.
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Affiliation(s)
- F M Konikoff
- Department of Gastroenterology, Sourasky Tel-Aviv Medical Center, Tel-Aviv University, Israel.
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