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377 Publications visible to you, out of a total of 377
Conditional loss of hepatocellular Hedgehog signaling in female mice leads to the persistence of hepatic steroidogenesis, androgenization and infertility

Abstract (Expand)

The Hedgehog signaling pathway is known to be involved in embryogenesis, tissue remodeling, and carcinogenesis. Because of its involvement in carcinogenesis, it seems an interesting target for cancer … therapy. Indeed, Sonidegib, an approved inhibitor of the Hedgehog receptor Smoothened (Smo), is highly active against diverse carcinomas, but its use is also reported to be associated with several systemic side effects. Our former work in adult mice demonstrated hepatic Hedgehog signaling to play a key role in the insulin-like growth factor axis and lipid metabolism. The current work using mice with an embryonic and hepatocyte-specific Smo deletion describes an adverse impact of the hepatic Hedgehog pathway on female fertility. In female SAC-KO mice, we detected androgenization characterized by a 3.3-fold increase in testosterone at 12 weeks of age based on an impressive induction of steroidogenic gene expression in hepatocytes, but not in the classic steroidogenic organs (ovary and adrenal gland). Along with the elevated level of testosterone, the female SAC-KO mice showed infertility characterized by juvenile reproductive organs and acyclicity. The endocrine and reproductive alterations resembled polycystic ovarian syndrome and could be confirmed in a second mouse model with conditional deletion of Smo at 8 weeks of age after an extended period of 8 months. We conclude that the down-regulation of hepatic Hedgehog signaling leads to an impaired hormonal balance by the induction of steroidogenesis in the liver. These effects of Hedgehog signaling inhibition should be considered when using Hedgehog inhibitors as anti-cancer drugs.

Authors: Christiane Rennert, Franziska Eplinius, Ute Hofmann, Janina Johänning, Franziska Rolfs, Wolfgang Schmidt-Heck, Reinhardt Guthke, Rolf Gebhardt, Albert M. Ricken, Madlen Matz-Soja

Date Published: 30th May 2017

Publication Type: Not specified

Large-scale computational models of liver metabolism: How far from the clinics?

Abstract (Expand)

Understanding the dynamics of human liver metabolism is fundamental for effective diagnosis and treatment of liver diseases in general and the metabolism of drugs in particular. This knowledge can be … obtained with systems biology/medicine approaches that account for the complexity of hepatic responses and their systemic consequences in other organs. Computational modelling can reveal hidden principles of the system by classification of individual components, analysing their interactions and simulating the effects that are difficult to investigate experimentally. Herein we review the state-of-the-art computational models that describe liver dynamics from the metabolic, gene regulatory and signal transduction perspectives. We focus especially on large-scale liver models described either by genome scale metabolic networks (GSMN) or object-oriented approach. We also discuss the benefits and limitations of each modelling approach and their value for clinical applications in diagnosis, therapy and prevention of liver diseases as well as precision medicine in hepatology. This article is protected by copyright. All rights reserved.

Authors: T. Cvitanovic, M. C. Reichert, M. Moskon, M. Mraz, F. Lammert, D. Rozman

Date Published: 19th May 2017

Publication Type: Not specified

Robust detection and segmentation of cell nuclei in biomedical images based on a computational topology framework

Abstract

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Authors: Rodrigo Rojas-Moraleda, Wei Xiong, Niels Halama, Katja Breitkopf-Heinlein, Steven Dooley, Luis Salinas, Dieter W. Heermann, Nektarios A. Valous

Date Published: 1st May 2017

Publication Type: Not specified

Quantification of substrate and cellular strains in stretchable 3D cell cultures: an experimental and computational framework

Abstract

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Authors: P. GONZÁLEZ-AVALOS, M. MÜRNSEER, J. DEEG, A. BACHMANN, J. SPATZ, S. DOOLEY, R. EILS, E. GLADILIN

Date Published: 1st May 2017

Publication Type: Not specified

Global Transcriptional Response of Human Liver Cells to Ethanol Stress of Different Strength Reveals Hormetic Behavior

Abstract

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Authors: Wolfgang Schmidt-Heck, Eva C. Wönne, Thomas Hiller, Uwe Menzel, Dirk Koczan, Georg Damm, Daniel Seehofer, Fanny Knöspel, Nora Freyer, Reinhard Guthke, Steven Dooley, Katrin Zeilinger

Date Published: 1st May 2017

Publication Type: Not specified

Ligand-dependent and -independent regulation of human hepatic sphingomyelin phosphodiesterase acid-like 3A expression by pregnane X receptor and crosstalk with liver X receptor.

Abstract (Expand)

Pregnane X receptor (PXR) mainly regulates xenobiotic metabolism and detoxification. Additionally, it exerts pleiotropic effects on liver physiology, which in large parts depend on transrepression of … other liver-enriched transcription factors. Based on the hypothesis that lower expression levels of PXR may reduce the extent of this inhibition, an exploratory genome-wide transcriptomic profiling was performed using HepG2 cell clones with different expression levels of PXR. This screen and confirmatory real-time RT-PCR identified sphingomyelin phosphodiesterase acid-like (SMPDL) 3A, a novel nucleotide phosphodiesterase and phosphoramidase, as being up-regulated by PXR-deficiency. Transient siRNA-mediated knock-down of PXR in HepG2 cells and primary human hepatocytes similarly induced mRNA up-regulation, which translated into increased intracellular and secreted extracellular protein levels. Interestingly, ligand-dependent PXR activation also induced SMPDL3A in HepG2 cells and primary human hepatocytes. Electrophoretic mobility shift assays and chromatin immunoprecipitation demonstrated binding of PXR to the previously identified liver X receptor (LXR)-binding DR4 motif as well as to an adjacent ER8 motif in intron 1 of SMPDL3A. Constitutive binding of the unliganded receptor to the intron 1 chromatin indicated ligand-independent repression of SMPDL3A by PXR. Transient transfection and reporter gene analysis confirmed the specific role of these motifs in PXR- and LXR-dependent activation of the SMPDL3A intronic enhancer. PXR inhibited LXR mainly by competition for binding sites. In conclusion, this study describes that a decrease in PXR expression levels and ligand-dependent activation of PXR and LXR increase hepatic SMPDL3A levels, which possibly connects these receptors to hepatic purinergic signaling and phospholipid metabolism and may result in drug-drug interactions with phosphoramidate pro-drugs.

Authors: J. Jeske, A. Bitter, W. E. Thasler, T. S. Weiss, M. Schwab, O. Burk

Date Published: 18th Apr 2017

Publication Type: Not specified

Towards knowledge-driven cross-species extrapolation

Abstract

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Authors: Christoph Thiel, Ute Hofmann, Ahmed Ghallab, Rolf Gebhardt, Jan G. Hengstler, Lars Kuepfer

Date Published: 1st Apr 2017

Publication Type: Not specified

BMP-9 interferes with liver regeneration and promotes liver fibrosis.

Abstract (Expand)

OBJECTIVE: Bone morphogenetic protein (BMP)-9, a member of the transforming growth factor-beta family of cytokines, is constitutively produced in the liver. Systemic levels act on many organs and tissues … including bone and endothelium, but little is known about its hepatic functions in health and disease. DESIGN: Levels of BMP-9 and its receptors were analysed in primary liver cells. Direct effects of BMP-9 on hepatic stellate cells (HSCs) and hepatocytes were studied in vitro, and the role of BMP-9 was examined in acute and chronic liver injury models in mice. RESULTS: Quiescent and activated HSCs were identified as major BMP-9 producing liver cell type. BMP-9 stimulation of cultured hepatocytes inhibited proliferation, epithelial to mesenchymal transition and preserved expression of important metabolic enzymes such as cytochrome P450. Acute liver injury caused by partial hepatectomy or single injections of carbon tetrachloride (CCl4) or lipopolysaccharide (LPS) into mice resulted in transient downregulation of hepatic BMP-9 mRNA expression. Correspondingly, LPS stimulation led to downregulation of BMP-9 expression in cultured HSCs. Application of BMP-9 after partial hepatectomy significantly enhanced liver damage and disturbed the proliferative response. Chronic liver damage in BMP-9-deficient mice or in mice adenovirally overexpressing the selective BMP-9 antagonist activin-like kinase 1-Fc resulted in reduced deposition of collagen and subsequent fibrosis. CONCLUSIONS: Constitutive expression of low levels of BMP-9 stabilises hepatocyte function in the healthy liver. Upon HSC activation, endogenous BMP-9 levels increase in vitro and in vivo and high levels of BMP-9 cause enhanced damage upon acute or chronic injury.

Authors: K. Breitkopf-Heinlein, C. Meyer, C. Konig, H. Gaitantzi, A. Addante, M. Thomas, E. Wiercinska, C. Cai, Q. Li, F. Wan, C. Hellerbrand, N. A. Valous, M. Hahnel, C. Ehlting, J. G. Bode, S. Muller-Bohl, U. Klingmuller, J. Altenoder, I. Ilkavets, M. J. Goumans, L. J. Hawinkels, S. J. Lee, M. Wieland, C. Mogler, M. P. Ebert, B. Herrera, H. Augustin, A. Sanchez, S. Dooley, P. Ten Dijke

Date Published: 25th Mar 2017

Publication Type: Not specified

BMP-9 interferes with liver regeneration and promotes liver fibrosis.

Abstract (Expand)

OBJECTIVE: Bone morphogenetic protein (BMP)-9, a member of the transforming growth factor-beta family of cytokines, is constitutively produced in the liver. Systemic levels act on many organs and tissues … including bone and endothelium, but little is known about its hepatic functions in health and disease. DESIGN: Levels of BMP-9 and its receptors were analysed in primary liver cells. Direct effects of BMP-9 on hepatic stellate cells (HSCs) and hepatocytes were studied in vitro, and the role of BMP-9 was examined in acute and chronic liver injury models in mice. RESULTS: Quiescent and activated HSCs were identified as major BMP-9 producing liver cell type. BMP-9 stimulation of cultured hepatocytes inhibited proliferation, epithelial to mesenchymal transition and preserved expression of important metabolic enzymes such as cytochrome P450. Acute liver injury caused by partial hepatectomy or single injections of carbon tetrachloride (CCl4) or lipopolysaccharide (LPS) into mice resulted in transient downregulation of hepatic BMP-9 mRNA expression. Correspondingly, LPS stimulation led to downregulation of BMP-9 expression in cultured HSCs. Application of BMP-9 after partial hepatectomy significantly enhanced liver damage and disturbed the proliferative response. Chronic liver damage in BMP-9-deficient mice or in mice adenovirally overexpressing the selective BMP-9 antagonist activin-like kinase 1-Fc resulted in reduced deposition of collagen and subsequent fibrosis. CONCLUSIONS: Constitutive expression of low levels of BMP-9 stabilises hepatocyte function in the healthy liver. Upon HSC activation, endogenous BMP-9 levels increase in vitro and in vivo and high levels of BMP-9 cause enhanced damage upon acute or chronic injury.

Authors: K. Breitkopf-Heinlein, C. Meyer, C. Konig, H. Gaitantzi, A. Addante, M. Thomas, E. Wiercinska, C. Cai, Q. Li, F. Wan, C. Hellerbrand, N. A. Valous, M. Hahnel, C. Ehlting, J. G. Bode, S. Muller-Bohl, U. Klingmuller, J. Altenoder, I. Ilkavets, M. J. Goumans, L. J. Hawinkels, S. J. Lee, M. Wieland, C. Mogler, M. P. Ebert, B. Herrera, H. Augustin, A. Sanchez, S. Dooley, P. Ten Dijke

Date Published: 23rd Mar 2017

Publication Type: Not specified

Physiologic Reduction of Hepatic Venous Blood Flow by the Valsalva Maneuver Decreases Liver Stiffness.

Abstract (Expand)

OBJECTIVES: Liver stiffness increases after intake of food or water, suggesting that hepatic venous blood flow affects the results of elastographic measurements. This study investigated the correlation … between in vivo liver stiffness and hepatic blood flow using the Valsalva maneuver for reducing intrahepatic venous blood flow. METHODS: Intrahepatic changes in venous blood flow were assessed by sonography based on the pulsed wave Doppler velocity, vessel diameter assessment, and blood flow volume measurements in the portal vein and right hepatic vein. Time-harmonic elastography at 7 harmonic driving frequencies (30-60 Hz) was used to measure liver stiffness in the right liver lobe of 15 healthy volunteers. RESULTS: The right hepatic vein diameter, flow volume, and peak pulsed wave velocity decreased during the Valsalva maneuver from mean +/- SD values of 8.64 +/- 1.85 to 6.55 +/- 1.84 mm (P = .002), 0.53 +/- 0.23 to 0.37 +/- 0.26 L/min (P = .037), and 22.14 +/- 4.87 to 17.38 +/- 5.41 cm/s (P = .01), respectively. This maneuver decreased liver stiffness in all volunteers by a mean of approximately 13% from 1.71 +/- 0.22 to 1.48 +/- 0.22 m/s (P = .00006). CONCLUSIONS: Our results demonstrate that liver stiffness is sensitive to altered venous blood flow, which is of clinical importance when using elastography for evaluation of portal hypertension. Furthermore, our results indicate that accurate measurement of liver stiffness requires standardized breathing conditions to rule out effects of changes in hepatic blood flow on elastographic findings.

Authors: S. Ipek-Ugay, H. Tzschatzsch, J. Braun, T. Fischer, I. Sack

Date Published: 20th Mar 2017

Publication Type: Not specified

A compact 0.5 T MR elastography device and its application for studying viscoelasticity changes in biological tissues during progressive formalin fixation.

Abstract (Expand)

PURPOSE: To develop a method of compact tabletop magnetic resonance elastography (MRE) for rheological tests of tissue samples and to measure changes in viscoelastic powerlaw constants of liver and … brain tissue during progressive fixation. METHODS: A 10-mm bore, 0.5-T permanent-magnet-based MRI system was equipped with a gradient-amplifier-controlled piezo-actuator and motion-sensitive spin echo sequence for inducing and measuring harmonic shear vibrations in cylindrical samples. Shear modulus dispersion functions were acquired at 200-5700 Hz in animal tissues at different states of formalin fixation and fitted by the springpot powerlaw model to obtain shear modulus mu and powerlaw exponent alpha. RESULTS: In a frequency range of 300-1500 Hz, unfixed liver tissue was softer and less dispersive than brain tissue with mu = 1.68 +/- 0.17 kPa and alpha = 0.51 +/- 0.06 versus mu = 2.60 +/- 0.68 kPa and alpha = 0.68 +/- 0.03. Twenty-eight hours of formalin fixation yielded a 400-fold increase in liver mu, 25-fold increase in brain mu, and two-fold reduction in alpha of both tissues. CONCLUSION: Compact 0.5-T MRE facilitates automated measurement of shear modulus dispersion in biological tissue at low costs. Formalin fixation changes the viscoelastic properties of tissues from viscous-soft to elastic-stiff more markedly in liver than brain. Magn Reson Med 79:470-478, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.

Authors: J. Braun, H. Tzschatzsch, C. Korting, A. Ariza de Schellenberger, M. Jenderka, T. Driessle, M. Ledwig, I. Sack

Date Published: 20th Mar 2017

Publication Type: Not specified

A Predictive 3D Multi-Scale Model of Biliary Fluid Dynamics in the Liver Lobule.

Abstract (Expand)

Bile, the central metabolic product of the liver, is transported by the bile canaliculi network. The impairment of bile flow in cholestatic liver diseases has urged a demand for insights into its … regulation. Here, we developed a predictive 3D multi-scale model that simulates fluid dynamic properties successively from the subcellular to the tissue level. The model integrates the structure of the bile canalicular network in the mouse liver lobule, as determined by high-resolution confocal and serial block-face scanning electron microscopy, with measurements of bile transport by intravital microscopy. The combined experiment-theory approach revealed spatial heterogeneities of biliary geometry and hepatocyte transport activity. Based on this, our model predicts gradients of bile velocity and pressure in the liver lobule. Validation of the model predictions by pharmacological inhibition of Rho kinase demonstrated a requirement of canaliculi contractility for bile flow in vivo. Our model can be applied to functionally characterize liver diseases and quantitatively estimate biliary transport upon drug-induced liver injury.

Authors: K. Meyer, O. Ostrenko, G. Bourantas, H. Morales-Navarrete, N. Porat-Shliom, F. Segovia-Miranda, H. Nonaka, A. Ghaemi, J. M. Verbavatz, L. Brusch, I. Sbalzarini, Y. Kalaidzidis, R. Weigert, M. Zerial

Date Published: 18th Mar 2017

Publication Type: Not specified

Panel of three novel serum markers predicts liver stiffness and fibrosis stages in patients with chronic liver disease.

Abstract (Expand)

Latest data suggest that placental growth factor (PLGF), growth differentiation factor-15 (GDF-15) and hepatic growth factor (HGF) are involved in hepatic fibrogenesis. Diagnostic performance of these … markers for non-invasive liver fibrosis prediction was evaluated based on liver histology and stiffness. In total 834 patients were recruited. Receiver-operating-characteristics were used to define cut-offs for markers correlating to fibrosis stages. Odds-ratios were calculated for the presence/absence of fibrosis/cirrhosis and confirmed in the sub-group of patients phenotyped by elastography only. Logistic and uni- and multivariate regression analyses were used to test for association of markers with liver fibrosis stages and for independent prediction of liver histology and stiffness. Marker concentrations correlated significantly (P<0.001) with histology and stiffness. Cut-offs for liver fibrosis (>/=F2) were PLGF = 20.20 pg/ml, GDF15 = 1582.76 pg/ml and HGF = 2598.00 pg/ml. Logistic regression confirmed an increase of ORs from 3.6 over 33.0 to 108.4 with incremental (1-3) markers positive for increased liver stiffness (>/=12.8kPa; all P<0.05). Subgroup analysis revealed associations with advanced fibrosis for HCV (three markers positive: OR = 59.9, CI 23.4-153.4, P<0.001) and non-HCV patients (three markers positive: OR = 144, CI 59-3383, P<0.001). Overall, serum markers identified additional 50% of patients at risk for advanced fibrosis presenting with low elastography results. In conclusion, this novel combination of markers reflects the presence of significant liver fibrosis detected by elastography and histology and may also identify patients at risk presenting with low elastography values.

Authors: M. Krawczyk, S. Zimmermann, G. Hess, R. Holz, M. Dauer, J. Raedle, F. Lammert, F. Grunhage

Date Published: 17th Mar 2017

Publication Type: Not specified

Pathophysiology and Management of Alcoholic Liver Disease: Update 2016.

Abstract (Expand)

Alcoholic liver disease (ALD) is a leading cause of cirrhosis, liver cancer, and acute and chronic liver failure and as such causes significant morbidity and mortality. While alcohol consumption is … slightly decreasing in several European countries, it is rising in others and remains high in many countries around the world. The pathophysiology of ALD is still incompletely understood but relates largely to the direct toxic effects of alcohol and its main intermediate, acetaldehyde. Recently, novel putative mechanisms have been identified in systematic scans covering the entire human genome and raise new hypotheses on previously unknown pathways. The latter also identify host genetic risk factors for significant liver injury, which may help design prognostic risk scores. The diagnosis of ALD is relatively easy with a panel of well-evaluated tests and only rarely requires a liver biopsy. Treatment of ALD is difficult and grounded in abstinence as the pivotal therapeutic goal; once cirrhosis is established, treatment largely resembles that of other etiologies of advanced liver damage. Liver transplantation is a sound option for carefully selected patients with cirrhosis and alcoholic hepatitis because relapse rates are low and prognosis is comparable to other etiologies. Still, many countries are restrictive in allocating donor livers for ALD patients. Overall, few therapeutic options exist for severe ALD. However, there is good evidence of benefit for only corticosteroids in severe alcoholic hepatitis, while most other efforts are of limited efficacy. Considering the immense burden of ALD worldwide, efforts of medical professionals and industry partners to develop targeted therapies in ALF has been disappointingly low.

Authors: F. Stickel, C. Datz, J. Hampe, R. Bataller

Date Published: 15th Mar 2017

Publication Type: Not specified

SABIO-RK, von Daten in der Publikation zur Suchlösung für Spezialisten

Abstract

Not specified

Authors: Wolfgang Müller, Meik Bittkowski, Martin Golebiewski, Renate Kania, Maja Rey, Andreas Weidemann, Ulrike Wittig

Date Published: 1st Mar 2017

Publication Type: Not specified

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