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Ulrich Beuers

Publications and source records attributed to Ulrich Beuers.

At least 19 recordsLinked to original sources
PubMed2006

Decreased expression of breast cancer resistance protein in the duodenum in patients with obstructive cholestasis.

BACKGROUND/AIMS: The expression of transporters involved in bile acid homeostasis is differentially regulated during obstructive cholestasis. Since the drug efflux transporter breast cancer resistance protein (BCRP) is known to transport bile acids, we investigated whether duodenal BCRP expression could be altered during cholestasis. METHODS: Using real-time RT-PCR analysis we determined mRNA expression levels in duodenal tissue of 19 cholestatic patients. Expression levels were compared to 14 healthy subjects. BCRP protein staining was determined in biopsies of 6 cholestatic and 6 healthy subjects by immunohistochemistry. RESULTS: We found that in patients with obstructive cholestasis mean duodenal BCRP mRNA levels were significantly reduced to 53% and mean protein staining was reduced to 57%. CONCLUSIONS: BCRP, a transporter for bile acids and numerous drugs, appears to be down-regulated in the human duodenum during cholestasis. The clinical impact of these results has to be investigated in further studies.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2006

Plasma separation and anion adsorption transiently relieve intractable pruritus in primary biliary cirrhosis.

BACKGROUND/AIMS: Pruritus can be a severely disabling symptom in patients with primary biliary cirrhosis who do not respond to treatment with ursodeoxycholic acid, anion exchangers, enzyme inducers, or opiate antagonists. The aim of this study was to assess the clinical efficacy of plasma separation and anion adsorption in the treatment of intractable pruritus of cholestasis. METHODS: Three patients with primary biliary cirrhosis and intractable pruritus defined by severity of pruritus 7 on a rating scale between 0 (no pruritus) and 10 (maximal pruritus) on at least 4 of 7 days despite medical treatment were treated with plasma separation and anion adsorption on three consecutive days. Fatigue was assessed using the Fisk Fatigue Severity Score and quality of life was assessed by the PBC-40, a disease specific health related quality of life measure. RESULTS: Improvement in pruritus, fatigue, and quality of life was transiently observed in all patients. Serum bile acid levels showed no association with intensity of pruritus, and the bile acid pattern was not altered. The treatment was well tolerated by all patients. CONCLUSIONS: Plasma separation and anion adsorption seem to be a safe and effective therapeutic option for patients with primary biliary cirrhosis suffering from intractable pruritus.

Adsorption↗
PubMed2006

Ursodeoxycholic acid treatment of vanishing bile duct syndromes.

Vanishing bile duct syndromes (VBDS) are characterized by progressive loss of small intrahepatic ducts caused by a variety of different diseases leading to chronic cholestasis, cirrhosis, and premature death from liver failure. The majority of adult patients with VBDS suffer from primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Ursodeoxycholic acid (UDCA), a hydrophilic dihydroxy bile acid, is the only drug currently approved for the treatment of patients with PBC, and anticholestatic effects have been reported for several other cholestatic syndromes. Several potential mechanisms of action of UDCA have been proposed including stimulation of hepatobiliary secretion, inhibition of apoptosis and protection of cholangiocytes against toxic effects of hydrophobic bile acids.

Apoptosis↗
PubMed2006

Pregnancy in autoimmune hepatitis: outcome and risk factors.

OBJECTIVE: Autoimmune hepatitis (AIH) may influence pregnancy outcome and pregnancy may affect AIH. We aimed at analyzing the disease course in pregnant AIH patients and at identifying disease-related risk factors for adverse pregnancy outcome. PATIENTS AND METHODS: AIH patients with at least one pregnancy were identified at four liver units. The patients' records and the data obtained by detailed questionnaires were analyzed retrospectively. Forty-two pregnancies of 22 AIH patients were included. RESULTS: The rate of adverse pregnancy outcome was 26%; a medical explanation could be elucidated in only 4 of 11 pregnancies with adverse outcome. Of note, the 7 unexplained adverse pregnancy outcomes were highly associated with the presence of antibodies to SLA/LP (odds ratio 51; p < 0.003) and Ro/SSA (odds ratio 27; p < 0.02). Of 35 live births, 30 children developed normally over a mean observation period of nearly 5 yr. Eleven of these had been exposed to azathioprine in utero. The rate of serious maternal complications was 9% and a high rate (52%) of postpartum flares was noted. CONCLUSIONS: The presence of autoantibodies may be a risk factor for adverse pregnancy outcome in AIH patients. Close monitoring of both mother and fetus seems advisable due to a significant rate of maternal and fetal complications.

Adolescent↗
PubMed2006

Tauroursodeoxycholic acid inserts the bile salt export pump into canalicular membranes of cholestatic rat liver.

Ursodeoxycholic acid exerts anticholestatic effects in chronic cholestatic liver disease in humans as well as in experimental animal models of cholestasis. Its taurine conjugate, TUDCA, was recently shown to stimulate insertion of the apical conjugate export pump, Mrp2 (ABCC2), into canalicular membranes of rat hepatocytes made cholestatic by exposure to taurolithocholic acid (TLCA). The aim of this immunoelectronmicroscopic study was to test whether TLCA and TUDCA modulate the canalicular density of the other key apical transporter, the bile salt export pump, Bsep (ABCB11), in a similar way. Immunoelectronmicroscopic analysis of Bsep density on canalicular membranes, microvilli, and pericanalicular area of hepatocytes was performed in rat liver tissue prepared after liver perfusion with bile acids or carrier medium only. TLCA (10 micromol/l for 50 min) decreased Bsep density in canalicular membranes to 31% of controls (P<0.05) when bile flow was reduced to 35% of controls (P<0.05). Concomitantly, Bsep density in a 1 microm pericanalicular zone increased to 202% (P<0.05) indicating effective retrieval of Bsep from the canalicular membrane induced by TLCA. Coadministration of TUDCA (25 micromol/l) led to a 3.2-fold increase of Bsep density in canalicular membranes equal to control liver (P<0.05 vs TLCA) in association with a 3.8-fold increase of bile flow (P<0.05 vs TLCA). Stimulation of apical membrane insertion of key transporters like the bile salt export pump, Bsep, and-as previously shown-the conjugate export pump, Mrp2, may contribute to the anticholestatic action of UDCA amides in cholestatic conditions.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

Drug insight: Mechanisms and sites of action of ursodeoxycholic acid in cholestasis.

Ursodeoxycholic acid (UDCA) exerts anticholestatic effects in various cholestatic disorders. Several potential mechanisms and sites of action of UDCA have been unraveled in clinical and experimental studies, which could explain its beneficial effects. The relative contribution of these mechanisms to the anticholestatic action of UDCA depends on the type and stage of the cholestatic injury. In early-stage primary biliary cirrhosis and primary sclerosing cholangitis, protection of injured cholangiocytes against the toxic effects of bile acids might prevail. Stimulation of impaired hepatocellular secretion by mainly post-transcriptional mechanisms, including stimulation of synthesis, targeting and apical membrane insertion of key transporters, seems to be relevant in more advanced cholestasis. In intrahepatic cholestasis of pregnancy, stimulation of impaired hepatocellular secretion could be crucial for rapid relief of pruritus and improvement of serum liver tests, as it is in some forms of drug-induced cholestasis. In cystic fibrosis, stimulation of cholangiocellular calcium-dependent secretion of chloride and bicarbonate ions could have a major impact. Inhibition of bile-acid-induced hepatocyte apoptosis can have a role in all states of cholestasis that are characterized by hepatocellular bile-acid retention. Different mechanisms of action could, therefore, contribute to the beneficial effect of UDCA under various cholestatic conditions.

Animals↗
PubMed2006

Multidrug resistance 1 genotype and disposition of budesonide in early primary biliary cirrhosis.

BACKGROUND: Budesonide, which is a dual substrate of P-glycoprotein, the product of the multidrug resistance 1 (MDR1) gene, and cytochrome P450 3A (CYP3A) has been proposed for treatment of early primary biliary cirrhosis (PBC). Recently, MDR1 gene polymorphisms have been discussed as a potential cause of glucocorticoid resistance. We tested the hypothesis that MDR1 gene polymorphisms affect absorption of oral budesonide. METHODS: In 21 patients with histologically proven early-stage (I/II) PBC and nine healthy subjects, we evaluated the impact of MDR1 single nucleotide polymorphisms (2,677G>T,A and 3,435C>T) on disposition of a single oral dose of 3 mg budesonide. CYP3A5 gene polymorphisms (6,986A>G) were analyzed in parallel. RESULTS: In MDR1 2,677 GG and 3,435 CC genotypes, absorption and elimination of budesonide were not significantly different from those in corresponding homozygous variants. Peak plasma levels and areas under the plasma concentration time curves (AUC) of budesonide were not lower in MDR1 3,435 CC with putatively high intestinal expression of P-glycoprotein than in MDR1 3,435 TT. Interestingly, in two CYP3A5*1/*3 carriers with high enzyme activity, lower AUC was noted than in 28 CYP3A5*3/*3 carriers with a deficient enzyme. CONCLUSION: Common MDR1 gene polymorphisms do not affect disposition of budesonide in early PBC.

Administration, Oral↗
PubMed2006

Nucleosomal DNA fragments in autoimmune diseases.

The inadequate response of immune cells to circulating apoptotic products, such as nucleosomal DNA fragments, is assumed to be a potent stimulus for the production of autoantibodies during the pathogenesis and progression of systemic lupus erythematosus (SLE). Here, we analyzed the levels of circulating nucleosomes, caspases, and C-reactive protein in sera of 244 individuals with various autoimmune diseases (155 with autoimmune hepatic disorders, 25 with ANCA-associated vasculitis, and 64 with various connective tissue diseases), and 32 healthy controls. Nucleosomes and caspase activities were significantly elevated in sera of patients with hepatic autoimmune diseases, connective tissue diseases, and particularly in ANCA-associated vasculitis when compared with healthy individuals. Nucleosomes showed a correlation with caspases, and caspases with C-reactive protein, but nucleosomes did not correlate with C-reactive protein. Serum levels of the apoptotic products, nucleosomes, and caspases are increased in various autoimmune diseases but may not be solely responsible for antinucleosome antibody production in SLE patients. It remains to be clarified whether qualitative changes in nucleosomes are linked with pathogenesis and disease progression in SLE.

Apoptosis↗
PubMed2005

The human transcription factor AP-1 is a mediator of bile acid-induced liver cell apoptosis.

Apoptosis induced by toxic bile acids is thought to contribute to liver injury during cholestasis. The transcription factor AP-1 is involved in the induction of apoptosis depending on stimulus and cell type. It is not known whether the major human toxic bile acid, glycochenodeoxycholic acid (GCDCA), modulates AP-1 in hepatocytes. Our data show that GCDCA (75 microM, 4 h) significantly upregulates cFos and JunB as demonstrated by microarray analysis and real-time PCR in HepG2-Ntcp hepatoma cells. GCDCA (75 microM, 4 h) also induced AP-1 activation as determined by EMSA that was most distinct after 30 min. In parallel, AP-1 transcriptional activity increased by 40% after exposure to GCDCA. Curcumin, an AP-1 inhibitor, dose-dependently reduced (1-25 microM) or completely abolished (50 microM) the apoptotic effect of GCDCA. Thus, GCDCA-induced upregulation of AP-1-dependent genes appears important for the cytotoxicity of this bile acid.

Amino Acid Chloromethyl Ketones↗
PubMed2005

Characterization of organic anion transporter regulation, glutathione metabolism and bile formation in the obese Zucker rat.

BACKGROUND/AIMS: Alterations in hepatobiliary transporters may render fatty livers more vulnerable against various toxic insults. METHODS: We therefore studied expression and function of key organic anion transporters and their transactivators in 8-week-old obese Zucker rats, an established model for non-alcoholic fatty liver disease. RESULTS: Compared to their heterozygous littermates, obese animals showed a significant reduction in canalicular bile salt secretion, which was paralleled by significantly diminished Oatp2 mRNA and protein levels together with reduced nuclear HNF3beta, while expression of bile salt export pump, organic anion transporter (Oatp) 1 and multidrug resistance-associated protein (Mrp) 4 were unchanged. Impaired bile salt-independent bile flow in obese rats was associated with a 50% reduction of biliary secretion of the Mrp 2 model-substrates glutathione disulfide and S-(2,4-dinitrophenyl)glutathione. In line Mrp2 protein expression was reduced by 50% in obese rats. CONCLUSIONS: Oatp2 and Mrp2 expression is decreased in fatty liver and may impair metabolism and biliary secretion of numerous xenobiotics. Reduction of bile salt secretion and absence of biliary GSH excretion may contribute to impaired bile flow and posthepatic disorders associated with biliary GSH depletion.

ATP-Binding Cassette Transporters↗
PubMed2005

Phosphatidylinositol 3-kinase-dependent signaling modulates taurochenodeoxycholic acid-induced liver injury and cholestasis in perfused rat livers.

Taurochenodeoxycholic acid (TCDCA), but not glycochenodeoxycholic acid (GCDCA), activates a phosphatidylinositol 3-kinase (PI3-K)-mediated survival pathway in vitro. Here, the effects of PI3-K inhibition on TCDCA- and GCDCA-induced hepatocellular injury, apoptosis, and bile secretion were examined in the intact liver. In isolated perfused rat livers, bile flow was determined gravimetrically. Hepatovenous lactate dehydrogenase and alanine aminotransferase efflux as markers of liver integrity and biliary secretion of 2,4-dinitrophenyl-S-glutathione (DNP-GS) were determined photometrically. Apoptosis was assessed by immunohistochemistry of active caspase-3 and cytokeratin 18 in liver tissue. Phosphorylation of protein kinase B (PKB/Akt) as a readout of PI3-K activity was determined by immunoblot analysis. Bile acid concentrations were determined by gas chromatography. TCDCA (25 muM) induced moderate liver injury by hepatocellular apoptosis and distinctly reduced bile flow and DNP-GS secretion. In contrast, GCDCA (25 muM) induced severe liver injury by extensive hepatocyte apoptosis. TCDCA strongly activated PI3-K, whereas GCDCA did not markedly affect PI3-K activity. Inhibition of PI3-K by 100 nM wortmannin enhanced TCDCA-induced liver injury and apoptosis and tended to aggravate the cholestatic effect of TCDCA. In contrast, wortmannin reduced GCDCA-induced liver injury and apoptosis. Bile acid uptake tended to be reduced by wortmannin. The cholestatic effect of GCDCA was aggravated by wortmannin. Inhibition of PI3-K markedly aggravated TCDCA-induced but not GCDCA-induced liver damage and hepatocyte apoptosis. Thus TCDCA appears to block its inherent toxicity by a PI3-K-dependent survival pathway in the intact liver.

Androstadienes↗
PubMed2005

No relevant effect of ursodeoxycholic acid on cytochrome P450 3A metabolism in primary biliary cirrhosis.

Induction of cytochrome P450 3A (CYP3A) has been suggested as a mechanism of action of ursodeoxycholic acid (UDCA) in cholestasis. CYP3A is of key importance in human drug metabolism, being involved in presystemic extraction of more than 50% of all drugs currently available and of various endogenous compounds. Therefore, we compared the induction potential of UDCA with that of the prototypical inducer rifampicin in a human model study with the CYP3A substrates budesonide and cortisol. Twelve patients with early-stage primary biliary cirrhosis and eight healthy volunteers were treated with UDCA (15 mg/kg daily) for 3 weeks and subsequently with rifampicin (600 mg/d) for 1 week. Extensive pharmacokinetic profiling of oral budesonide (3 mg) was performed by determination of budesonide and phase I metabolites (6beta-hydroxybudesonide, 16alpha-hydroxyprednisolone) in plasma and urine at baseline and at the end of each treatment. In parallel, urinary 6beta-hydroxycortisol, a validated marker of CYP3A induction, was determined. UDCA did not affect biotransformation of budesonide and urinary excretion of 6beta-hydroxycortisol either in patients or in healthy volunteers. Ratios of areas under plasma concentration-time curves (AUC(0-12 h) during UDCA/AUC(0-12 h) before UDCA) of both metabolites were not higher than those of budesonide itself. In contrast, administration of rifampicin markedly induced CYP3A metabolism, resulting in abolished budesonide plasma levels and high urinary excretion of 6beta-hydroxycortisol. Metabolite formation was enhanced by rifampicin, but not by UDCA (e.g., AUC(16alpha-hydroxyprednisolone)/AUC(budesonide) in patients: baseline, 8.6 +/- 3.9; UDCA, 10.7 +/- 7.1; rifampicin, 527.0 +/- 248.7). In conclusion, UDCA is not a relevant inducer of CYP3A enzymes in humans.

Adult↗
PubMed2005

Efficacy and safety of ursodeoxycholic acid versus cholestyramine in intrahepatic cholestasis of pregnancy.

BACKGROUND & AIMS: Treatment of intrahepatic cholestasis of pregnancy with ursodeoxycholic acid appears promising, but data are limited so far. The aim of this randomized study was to evaluate the efficacy and safety of ursodeoxycholic acid in comparison with cholestyramine. METHODS: Eighty-four symptomatic patients with intrahepatic cholestasis of pregnancy were randomized to receive either ursodeoxycholic acid, 8-10 mg/kg body weight daily (n = 42), or cholestyramine, 8 g daily (n = 42), for 14 days. The primary end point was a reduction of pruritus by more than 50% after 14 days of treatment as evaluated by a pruritus score. Secondary end points were outcome of pregnancy, reduction of serum aminotransferase activities and serum bile acid levels, and drug safety. Intention-to-treat analysis was applied. RESULTS: Pruritus was more effectively reduced by ursodeoxycholic acid than cholestyramine (66.6% vs 19.0%, respectively; P < .005). Babies were delivered significantly closer to term by patients treated with ursodeoxycholic acid than those treated with cholestyramine (38.7 +/- 1.7 vs 37.4 +/- 1.5 weeks, respectively, P < .05). Serum alanine and aspartate aminotransferase activities were markedly reduced by 78.5% and 73.8%, respectively, after ursodeoxycholic acid, but by only 21.4%, each, after cholestyramine therapy (P < .01 vs ursodeoxycholic acid). Endogenous serum bile acid levels decreased by 59.5% and 19.0%, respectively (P < .02). Ursodeoxycholic acid, but not cholestyramine was free of adverse effects. CONCLUSIONS: Ursodeoxycholic acid is safe and more effective than cholestyramine in intrahepatic cholestasis of pregnancy.

Adult↗
PubMed2005

Overlap syndromes.

In hepatology, the term overlap syndrome describes variant forms of the major hepatobiliary autoimmune diseases, autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC). Patients with overlap syndromes present with both hepatitic and cholestatic biochemical and histological features of AIH, PBC, and/or PSC, and usually show a progressive course toward liver cirrhosis and liver failure without adequate treatment. AIH-PBC overlap syndromes have been reported in almost 10% of adults with AIH or PBC, whereas AIH-PSC overlap syndromes were found in 6 to 8% of children, adolescents, and young adults with AIH or PSC. A minority of patients may also show transition from stable PBC to AIH, AIH to PBC, or AIH to PSC, as documented by single case reports and small case series. Single cases of AIH and autoimmune cholangitis (antimitochondrial antibody-negative PBC) overlap have also been reported. Empiric medical treatment of AIH-PBC and AIH-PSC overlap syndromes includes anticholestatic therapy with ursodeoxycholic acid and immunosuppressive therapy with corticosteroids and azathioprine. In end-stage disease, liver transplantation is the treatment of choice.

Adult↗
PubMed2005

Budesonide in previously untreated autoimmune hepatitis.

BACKGROUND: Autoimmune hepatitis (AIH) is a chronic liver disease that is effectively treated with immunosuppressive therapy. Predniso(lo)ne, often in combination with azathioprine, is the basic therapeutic option to induce remission. However, this regimen can cause numerous side effects. The aim of the present study was to evaluate budesonide as a treatment option in the induction of remission in patients with previously untreated AIH. METHODS: Between October 1998 and August 1999, 12 patients were treated with 3 mg budesonide thrice daily for 3 months in this open one-arm multicenter phase IIa study. Primary end point was induction of remission indicated by a drop of aspartate aminotransferase and alanine aminotransferase levels below two times the upper limit of normal. RESULTS: Seven of the 12 patients (58%) reached complete remission, three patients (25%) had a partial response. Thus, 10/12 individuals (83.3%) responded to therapy. Therapy was tolerated well in 10/12 cases (83.3%). CONCLUSIONS: Budesonide monotherapy was effective in the induction of remission and well tolerated in treatment naïve patients with AIH. It should be further evaluated in prospective controlled trials and should be compared to predniso(lo)ne both in monotherapy and in combination with azathioprine.

Adult↗