Browsing by Author "Miquel, Juan F."

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    Cholecystectomy increases hepatic triglyceride content and very-low-density lipoproteins production in mice
    (WILEY, 2011) Amigo, Ludwig; Husche, Constanze; Zanlungo, Silvana; Luetjohann, Dieter; Arrese, Marco; Miquel, Juan F.; Rigotti, Attilio; Nervi, Flavio
    Background & aims: Bile acid (BA) pool size remains unchanged after cholecystectomy (XGB) but it circulates faster, exposing the enterohepatic system to an increased flux of BA. Triglyceride (TG) and BA metabolisms are functionally inter-related. We investigated whether ablation of the gallbladder (GB) modifies hepatic TG metabolism. Methods: Male mice were subjected to XGB and fed a normal diet. In some experiments, mice received a 1% nicotinic acid diet to block lipolysis. Parameters of BA and TG metabolism, and microsomal triglyceride transfer protein (MTTP) activity were measured 1-2 months after XGB. Serum parameters, hepatic lipids and mRNA expression of genes of lipid metabolism were determined. Results: BA pool size and synthesis were normal, but biliary BA secretion doubled during the diurnal light phase in XGB mice. Serum and hepatic TG concentrations increased 25% (P < 0.02), and hepatic very-low-density lipoproteins (VLDL)-TG and apoB-48 productions increased 15% (P < 0.03) and 50% (P < 0.01), respectively, after XGB. Feeding a 1% nicotinic acid did normalize VLDL production. MTTP activity increased 15% (P < 0.005) after XGB. Hepatic free fatty acid (FFA) synthesis and content, and mRNA levels of lipid metabolism-related genes remained normal in XGD mice. Conclusions: XGB increased serum and hepatic TG levels, and VLDL production, which were restored to normal by nicotinic acid. The results suggest that FFA flux from adipose tissue to the liver is increased in XGB mice. They support the hypothesis that the GB has a role in the regulation of hepatic TG metabolism and that XGB may favour the accumulation of fat in the liver.
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    Loci From a Genome-Wide Analysis of Bilirubin Levels Are Associated With Gallstone Risk and Composition
    (W B SAUNDERS CO-ELSEVIER INC, 2010) Buch, Stephan; Schafmayer, Clemens; Voelzke, Henry; Seeger, Marcus; Miquel, Juan F.; Sookoian, Silvia C.; Egberts, Jan H.; Arlt, Alexander; Pirola, Carlos J.; Lerch, Markus M.; John, Ulrich; Franke, Andre; von Kampen, Oliver; Brosch, Mario; Nothnagel, Michael; Kratzer, Wolfgang; Boehm, Bernhard O.; Broering, Dieter C.; Schreiber, Stefan; Krawczak, Michael; Hampe, Jochen
    BACKGROUND & AIMS: Genome-wide association studies have mapped loci that are associated with serum levels of bilirubin. Bilirubin is a major component of gallstones so we investigated whether these variants predict gallstone bilirubin content and overall risk for gallstones. METHODS: Loci that were identified in a meta-analysis to attain a genome-wide significance level of a P value less than 1.0 x 10(-7) (UGT1A1, SLCO1B1, LST-3TM12, SLCO1A2) were analyzed in 1018 individuals with known gallstone composition. Gallstone risk was analyzed in 2606 German choleystecomized individuals and 1121 controls and was replicated in 210 cases and 496 controls from South America. RESULTS: By using the presence of bilirubin as a phenotype, variants rs6742078 (UGT1A1; P = .003), rs4149056 (SLCO1B1; P = .003), and rs4149000 (SLCO1A2; P = .015) were associated with gallstone composition. In regression analyses, only UGT1A1 and SLCO1B1 were independently retained in the model. UGT1A1 (rs6742078; P = .018) was associated with overall gallstone risk. In a sex-stratified analysis, only male carriers of rs6742078 had an increased risk for gallstone disease (P = 2.1 x 10(-7); odds ratio(recessive), 2.34; P-women = .47). The sex-specific association of rs6742078 was confirmed in samples from South America (P-men = .046; odds ratio(recessive), 2.19; P-women = .96). CONCLUSIONS: The UGT1A1 Gilbert syndrome variant rs6742078 is associated with gallstone disease in men; further studies are required regarding the sex-specific physiology of bilirubin and bile acid metabolism. Variants of ABCG8 and UGT1A1 are the 2 major risk factors for overall gallstone disease, they contribute a population attributable risk of 21.2% among men.