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The Systems Biology Markup Language (SBML): Language Specification for Level 3 Version 2 Core Release 2.

Abstract (Expand)

Computational models can help researchers to interpret data, understand biological functions, and make quantitative predictions. The Systems Biology Markup Language (SBML) is a file format for representing … computational models in a declarative form that different software systems can exchange. SBML is oriented towards describing biological processes of the sort common in research on a number of topics, including metabolic pathways, cell signaling pathways, and many others. By supporting SBML as an input/output format, different tools can all operate on an identical representation of a model, removing opportunities for translation errors and assuring a common starting point for analyses and simulations. This document provides the specification for Release 2 of Version 2 of SBML Level 3 Core. The specification defines the data structures prescribed by SBML as well as their encoding in XML, the eXtensible Markup Language. Release 2 corrects some errors and clarifies some ambiguities discovered in Release 1. This specification also defines validation rules that determine the validity of an SBML document, and provides many examples of models in SBML form. Other materials and software are available from the SBML project website at http://sbml.org/.

Authors: M. Hucka, F. T. Bergmann, C. Chaouiya, A. Drager, S. Hoops, S. M. Keating, M. Konig, N. L. Novere, C. J. Myers, B. G. Olivier, S. Sahle, J. C. Schaff, R. Sheriff, L. P. Smith, D. Waltemath, D. J. Wilkinson, F. Zhang

Date Published: 20th Jun 2019

Publication Type: Not specified

Liquid-crystal organization of liver tissue.

Abstract (Expand)

Functional tissue architecture originates by self-assembly of distinct cell types, following tissue-specific rules of cell-cell interactions. In the liver, a structural model of the lobule was pioneered … by Elias in 1949. This model, however, is in contrast with the apparent random 3D arrangement of hepatocytes. Since then, no significant progress has been made to derive the organizing principles of liver tissue. To solve this outstanding problem, we computationally reconstructed 3D tissue geometry from microscopy images of mouse liver tissue and analyzed it applying soft-condensed-matter-physics concepts. Surprisingly, analysis of the spatial organization of cell polarity revealed that hepatocytes are not randomly oriented but follow a long-range liquid-crystal order. This does not depend exclusively on hepatocytes receiving instructive signals by endothelial cells, since silencing Integrin-beta1 disrupted both liquid-crystal order and organization of the sinusoidal network. Our results suggest that bi-directional communication between hepatocytes and sinusoids underlies the self-organization of liver tissue.

Authors: H. Morales-Navarrete, H. Nonaka, A. Scholich, F. Segovia-Miranda, W. de Back, K. Meyer, R. L. Bogorad, V. Koteliansky, L. Brusch, Y. Kalaidzidis, F. Julicher, B. M. Friedrich, M. Zerial

Date Published: 17th Jun 2019

Publication Type: Not specified

Correlative SMLM and electron tomography reveals endosome nanoscale domains.

Abstract (Expand)

Many cellular organelles, including endosomes, show compartmentalization into distinct functional domains, which however cannot be resolved by diffraction-limited light microscopy. Single molecule … localization microscopy (SMLM) offers nanoscale resolution but data interpretation is often inconclusive when the ultrastructural context is missing. Correlative light electron microscopy (CLEM) combining SMLM with electron microscopy (EM) enables correlation of functional sub-domains of organelles in relation to their underlying ultrastructure at nanometer resolution. However, the specific demands for EM sample preparation and the requirements for fluorescent single-molecule photo-switching are opposed. Here, we developed a novel superCLEM workflow that combines triple-colour SMLM (dSTORM & PALM) and electron tomography using semi-thin Tokuyasu thawed cryosections. We applied the superCLEM approach to directly visualize nanoscale compartmentalization of endosomes in HeLa cells. Internalized, fluorescently labelled Transferrin and EGF were resolved into morphologically distinct domains within the same endosome. We found that the small GTPase Rab5 is organized in nano-domains on the globular part of early endosomes. The simultaneous visualization of several proteins in functionally distinct endosomal sub-compartments demonstrates the potential of superCLEM to link the ultrastructure of organelles with their molecular organization at nanoscale resolution. This article is protected by copyright. All rights reserved.

Authors: C. Franke, U. Repnik, S. Segeletz, N. Brouilly, Y. Kalaidzidis, J. M. Verbavatz, M. Zerial

Date Published: 17th Jun 2019

Publication Type: Not specified

Glial cell line-derived neurotrophic factor (GDNF) mediates hepatic stellate cell activation via ALK5/Smad signalling.

Abstract (Expand)

OBJECTIVE: Although glial cell line-derived neurotrophic factor (GDNF) is a member of the transforming growth factor-beta superfamily, its function in liver fibrosis has rarely been studied. Here, we … investigated the role of GDNF in hepatic stellate cell (HSC) activation and liver fibrosis in humans and mice. DESIGN: GDNF expression was examined in liver biopsies and sera from patients with liver fibrosis. The functional role of GDNF in liver fibrosis was examined in mice with adenoviral delivery of the GDNF gene, GDNF sgRNA CRISPR/Cas9 and the administration of GDNF-blocking antibodies. GDNF was examined on HSC activation using human and mouse primary HSCs. The binding of activin receptor-like kinase 5 (ALK5) to GDNF was determined using surface plasmon resonance (SPR), molecular docking, mutagenesis and co-immunoprecipitation. RESULTS: GDNF mRNA and protein levels are significantly upregulated in patients with stage F4 fibrosis. Serum GDNF content correlates positively with alpha-smooth muscle actin (alpha-SMA) and Col1A1 mRNA in human fibrotic livers. Mice with overexpressed GDNF display aggravated liver fibrosis, while mice with silenced GDNF expression or signalling inhibition by GDNF-blocking antibodies have reduced fibrosis and HSC activation. GDNF is confined mainly to HSCs and contributes to HSC activation through ALK5 at His(39) and Asp(76) and through downstream signalling via Smad2/3, but not through GDNF family receptor alpha-1 (GFRalpha1). GDNF, ALK5 and alpha-SMA colocalise in human and mouse HSCs, as demonstrated by confocal microscopy. CONCLUSIONS: GDNF promotes HSC activation and liver fibrosis through ALK5/Smad signalling. Inhibition of GDNF could be a novel therapeutic strategy to combat liver fibrosis.

Authors: L. Tao, W. Ma, L. Wu, M. Xu, Y. Yang, W. Zhang, W. Sha, H. Li, J. Xu, R. Feng, D. Xue, J. Zhang, S. Dooley, E. Seki, P. Liu, C. Liu

Date Published: 6th Jun 2019

Publication Type: Not specified

Local Riemannian geometry of model manifolds and its implications for practical parameter identifiability

Abstract (Expand)

When non-linear models are fitted to experimental data, parameter estimates can be poorly constrained albeit being identifiable in principle. This means that along certain paths in parameter space, the … log-likelihood does not exceed a given statistical threshold but remains bounded. This situation, denoted as practical non-identifiability, can be detected by Monte Carlo sampling or by systematic scanning using the profile likelihood method. In contrast, any method based on a Taylor expansion of the log-likelihood around the optimum, e.g., parameter uncertainty estimation by the Fisher Information Matrix, reveals no information about the boundedness at all. In this work, we present a geometric approach, approximating the original log-likelihood by geodesic coordinates of the model manifold. The Christoffel Symbols in the geodesic equation are fixed to those obtained from second order model sensitivities at the optimum. Based on three exemplary non-linear models we show that the information about the log-likelihood bounds and flat parameter directions can already be contained in this local information. Whereas the unbounded case represented by the Fisher Information Matrix is embedded in the geometric framework as vanishing Christoffel Symbols, non-vanishing constant Christoffel Symbols prove to define prototype non-linear models featuring boundedness and flat parameter directions of the log-likelihood. Finally, we investigate if those models could allow to approximate and replace computationally expensive objective functions originating from non-linear models by a surrogate objective function in parameter estimation problems.

Authors: Daniel Lill, Jens Timmer, Daniel Kaschek

Date Published: 3rd Jun 2019

Publication Type: Not specified

Mapping connections in signaling networks with ambiguous modularity.

Abstract (Expand)

Modular Response Analysis (MRA) is a suite of methods that under certain assumptions permits the precise reconstruction of both the directions and strengths of connections between network modules from … network responses to perturbations. Standard MRA assumes that modules are insulated, thereby neglecting the existence of inter-modular protein complexes. Such complexes sequester proteins from different modules and propagate perturbations to the protein abundance of a downstream module retroactively to an upstream module. MRA-based network reconstruction detects retroactive, sequestration-induced connections when an enzyme from one module is substantially sequestered by its substrate that belongs to a different module. Moreover, inferred networks may surprisingly depend on the choice of protein abundances that are experimentally perturbed, and also some inferred connections might be false. Here, we extend MRA by introducing a combined computational and experimental approach, which allows for a computational restoration of modular insulation, unmistakable network reconstruction and discrimination between solely regulatory and sequestration-induced connections for a range of signaling pathways. Although not universal, our approach extends MRA methods to signaling networks with retroactive interactions between modules arising from enzyme sequestration effects.

Authors: D. Lill, O. S. Rukhlenko, A. J. Mc Elwee, E. Kashdan, J. Timmer, B. N. Kholodenko

Date Published: 1st Jun 2019

Publication Type: Not specified

Characterization of Lipid and Lipid Droplet Metabolism in Human HCC.

Abstract (Expand)

Human hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and the most common cause of death in people with cirrhosis. While previous metabolic studies of HCC have … mainly focused on the glucose metabolism (Warburg effect), less attention has been paid to tumor-specific features of the lipid metabolism. Here, we applied a computational approach to analyze major pathways of fatty acid utilization in individual HCC. To this end, we used protein intensity profiles of eleven human HCCs to parameterize tumor-specific kinetic models of cellular lipid metabolism including formation, enlargement, and degradation of lipid droplets (LDs). Our analysis reveals significant inter-tumor differences in the lipid metabolism. The majority of HCCs show a reduced uptake of fatty acids and decreased rate of beta-oxidation, however, some HCCs display a completely different metabolic phenotype characterized by high rates of beta-oxidation. Despite reduced fatty acid uptake in the majority of HCCs, the content of triacylglycerol is significantly enlarged compared to the tumor-adjacent tissue. This is due to tumor-specific expression profiles of regulatory proteins decorating the surface of LDs and controlling their turnover. Our simulations suggest that HCCs characterized by a very high content of triglycerides comprise regulatory peculiarities that render them susceptible to selective drug targeting without affecting healthy tissue.

Authors: N. Berndt, J. Eckstein, N. Heucke, R. Gajowski, M. Stockmann, D. Meierhofer, H. G. Holzhutter

Date Published: 27th May 2019

Publication Type: Not specified

Liver Fibrosis and Metabolic Alterations in Adults With alpha-1-antitrypsin Deficiency Caused by the Pi*ZZ Mutation.

Abstract (Expand)

BACKGROUND & AIMS: Alpha-1 antitrypsin deficiency (AATD) is among the most common genetic disorders. Severe AATD is caused by a homozygous mutation in the SERPINA1 gene that encodes the Glu342Lys … substitution (called the Pi*Z mutation, Pi*ZZ genotype). Pi*ZZ carriers may develop lung and liver diseases. Mutation-associated lung disorders have been well studied, but less is known about the effects in liver. We assessed the liver disease burden and associated features in adults with this form of AATD. METHODS: We collected data from 554 Pi*ZZ adults (403 in an exploratory cohort, 151 in a confirmatory cohort), in 9 European countries, with AATD who were homozygous for the Pi*Z mutation, and 234 adults without the Pi*Z mutation (controls), all without pre-existing liver disease. We collected data on demographic parameters, comorbidities, lung- and liver-related health, and blood samples for laboratory analysis. Liver fibrosis was assessed non-invasively via the serum tests Aspartate Aminotransferase to Platelet Ratio Index and HepaScore and via transient elastography. Liver steatosis was determined via transient elastography-based controlled attenuation parameter. We performed histologic analyses of livers from transgenic mice that overexpress the AATD-associated Pi*Z variant. RESULTS: Serum levels of liver enzymes were significantly higher in Pi*ZZ carriers vs controls. Based on non-invasive tests for liver fibrosis, significant fibrosis was suspected in 20%-36% of Pi*ZZ carriers, whereas signs of advanced fibrosis were 9- to 20-fold more common in Pi*ZZ carriers compared to non-carriers. Male sex; age older than 50 years; increased levels of alanine aminotransferase, aspartate aminotransferase, or gamma-glutamyl transferase; and low numbers of platelets were associated with higher liver fibrosis burden. We did not find evidence for a relationship between lung function and liver fibrosis. Controlled attenuation parameter >/=280 dB/m, suggesting severe steatosis, was detected in 39% of Pi*ZZ carriers vs 31% of controls. Carriers of Pi*ZZ had lower serum concentrations of triglyceride and low- and very-low-density lipoprotein cholesterol than controls, suggesting impaired hepatic secretion of lipid. Livers from Pi*Z-overexpressing mice had steatosis and down-regulation of genes involved in lipid secretion. CONCLUSIONS: In studies of AATD adults with the Pi*ZZ mutation, and of Pi*Z-overexpressing mice, we found evidence of liver steatosis and impaired lipid secretion. We identified factors associated with significant liver fibrosis in patients, which could facilitate hepatologic assessment and counseling of individuals who carry the Pi*ZZ mutation. ClinicalTrials.gov Number NCT02929940.

Authors: K. Hamesch, M. Mandorfer, V. M. Pereira, L. S. Moeller, M. Pons, G. E. Dolman, M. C. Reichert, C. V. Schneider, V. Woditsch, J. Voss, C. Lindhauer, M. Fromme, I. Spivak, N. Guldiken, B. Zhou, A. Arslanow, B. Schaefer, H. Zoller, E. Aigner, T. Reiberger, M. Wetzel, B. Siegmund, C. Simoes, R. Gaspar, L. Maia, D. Costa, M. Bento-Miranda, J. van Helden, E. Yagmur, D. Bzdok, J. Stolk, W. Gleiber, V. Knipel, W. Windisch, R. Mahadeva, R. Bals, R. Koczulla, M. Barrecheguren, M. Miravitlles, S. Janciauskiene, F. Stickel, F. Lammert, R. Liberal, J. Genesca, W. J. Griffiths, M. Trauner, A. Krag, C. Trautwein, P. Strnad

Date Published: 24th May 2019

Publication Type: Not specified

Expression Analysis of Fibronectin Type III Domain-Containing (FNDC) Genes in Inflammatory Bowel Disease and Colorectal Cancer.

Abstract (Expand)

Background: Fibronectin type III domain-containing (FNDC) proteins fulfill manifold functions in tissue development and regulation of cellular metabolism. FNDC4 was described as anti-inflammatory factor, … upregulated in inflammatory bowel disease (IBD). FNDC signaling includes direct cell-cell interaction as well as release of bioactive peptides, like shown for FNDC4 or FNDC5. The G-protein-coupled receptor 116 (GPR116) was found as a putative FNDC4 receptor. We here aim to comprehensively analyze the mRNA expression of FNDC1, FNDC3A, FNDC3B, FNDC4, FNDC5, and GPR116 in nonaffected and affected mucosal samples of patients with IBD or colorectal cancer (CRC). Methods: Mucosa samples were obtained from 30 patients undergoing diagnostic colonoscopy or from surgical resection of IBD or CRC. Gene expression was determined by quantitative real-time PCR. In addition, FNDC expression data from publicly available Gene Expression Omnibus (GEO) data sets (GDS4296, GDS4515, and GDS5232) were analyzed. Results: Basal mucosal expression revealed higher expression of FNDC3A and FNDC5 in the ileum compared to colonic segments. FNDC1 and FNDC4 were significantly upregulated in IBD. None of the investigated FNDCs was differentially expressed in CRC, just FNDC3A trended to be upregulated. The GEO data set analysis revealed significantly downregulated FNDC4 and upregulated GPR116 in microsatellite unstable (MSI) CRCs. The expression of FNDCs and GPR116 was independent of age and sex. Conclusions: FNDC1 and FNDC4 may play a relevant role in the pathobiology of IBD, but none of the investigated FNDCs is regulated in CRC. GPR116 may be upregulated in advanced or MSI CRC. Further studies should validate the altered FNDC expression results on protein levels and examine the corresponding functional consequences.

Authors: T. Wuensch, J. Wizenty, J. Quint, W. Spitz, M. Bosma, O. Becker, A. Adler, W. Veltzke-Schlieker, M. Stockmann, S. Weiss, M. Biebl, J. Pratschke, F. Aigner

Date Published: 17th May 2019

Publication Type: Not specified

Sensitivity of multifrequency magnetic resonance elastography and diffusion-weighted imaging to cellular and stromal integrity of liver tissue.

Abstract (Expand)

Microscopic structural alterations of liver tissue induced by freeze-thaw cycles give rise to palpable property changes. However, the underlying damage to tissue architecture is difficult to quantify … histologically, and published data on macroscopic changes in biophysical properties are sparse. To better understand the influence of hepatic cells and stroma on global biophysical parameters, we studied rat liver specimens freshly taken (within 30min after death) and treated by freeze-thaw cycles overnight at either -20 degrees C or -80 degrees C using diffusion-weighted imaging (DWI) and multifrequency magnetic resonance elastography (MRE) performed at 0.5T in a tabletop MRE scanner. Tissue structure was analyzed histologically and rheologic data were analyzed using fractional order derivatives conceptualized by a called spring-pot component that interpolates between pure elastic and viscous responses. Overnight freezing and thawing induced membrane disruptions and cell detachment in the space of Disse, resulting in a markedly lower shear modulus mu and apparent diffusion coefficient (ADC) (mu[-20 degrees C]=1.23+/-0.73kPa, mu[-80 degrees C]=0.66+/-0.75kPa; ADC[-20 degrees C]=0.649+/-0.028mum(2)/s, ADC[-80 degrees C]=0.626+/-0.025mum(2)/s) compared to normal tissue (mu=9.92+/-3.30kPa, ADC=0.770+/-0.023mum(2)/s, all p<0.001). Furthermore, we analyzed the springpot-powerlaw coefficient and observed a reduction in -20 degrees C specimens (0.22+/-0.14) compared to native tissue (0.40+/-0.10, p=0.033) and -80 degrees C specimens (0.54+/-0.22, p=0.002), that correlated with histological observations of sinusoidal dilation and collagen distortion within the space of Disse. Overall, the results suggest that shear modulus and water diffusion in liver tissue markedly decrease due to cell membrane degradation and cell detachment while viscosity-related properties appear to be more sensitive to distorted stromal and microvascular architecture.

Authors: A. A. de Schellenberger, H. Tzschatzsch, B. Polchlopek, G. Bertalan, F. Schrank, K. Garczynska, P. A. Janmey, J. Braun, I. Sack

Date Published: 9th May 2019

Publication Type: Not specified

Tomoelastography for the Evaluation of Pediatric Nonalcoholic Fatty Liver Disease

Abstract (Expand)

OBJECTIVES: Today, nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children and adults alike. Yet, the noninvasive evaluation of disease severity remains a diagnostic …c challenge. In this study, we apply multifrequency magnetic resonance elastography (mMRE) for the quantification of liver steatosis and fibrosis in adolescents with NAFLD. METHODS: Fifty adolescents (age range, 10-17 years; mean BMI, 33.9 kg/m; range, 21.4-42.1 kg/m) with biopsy-proven NAFLD were included in this prospective study. Multifrequency magnetic resonance elastography was performed using external multifrequency vibrations of 30 to 60 Hz and tomoelastography postprocessing, resulting in penetration rate (a) and shear wave speed (c). Hepatic fat fraction was determined using Dixon method. The diagnostic accuracy of mMRE in grading liver steatosis and staging liver fibrosis was assessed by receiver operating characteristic curve analysis. RESULTS: Multifrequency magnetic resonance elastography parameters c and a were independently sensitive to fibrosis and steatosis, respectively, providing area under the receiver operating characteristic values of 0.79 (95% confidence interval [CI], 0.66-0.92), 0.91 (95% CI, 0.83-0.99), and 0.90 (95% CI, 0.80-0.99) for the detection of any (≥F1), moderate (≥F2), and advanced (≥F3) fibrosis, and 0.87 (95% CI, 0.76-0.97) and 0.87 (95% CI, 0.77-0.96) for the detection of moderate (≥S2) and severe (S3) steatosis. CONCLUSIONS: One mMRE measurement provides 2 independent parameters with very good diagnostic accuracy in detecting moderate and advanced fibrosis as well as moderate and severe steatosis in pediatric NAFLD.

Authors: Christian A. Hudert, Heiko Tzschätzsch, Birgit Rudolph, Hendrik Bläker, Christoph Loddenkemper, Hans-Peter Müller, Stephan Henning, Philip Bufler, Bernd Hamm, Jürgen Braun, Hermann-Georg Holzhütter, Susanna Wiegand, Ingolf Sack, Jing Guo

Date Published: 1st Apr 2019

Publication Type: Not specified

Identification of serological markers for pre- and postoperative fasting periods.

Abstract (Expand)

BACKGROUND & AIMS: Prolonged preoperative fasting periods lead to catabolic states and decelerate recovery after surgery. Valid plasma markers reflecting the patients' metabolic state may improve … tailored nutrition support before surgery. Within this study, we sought to advance the knowledge on fasting time-sensitive plasma markers that allow the metabolic characterisation of surgical patients for an optimised preoperative metabolic preparation. METHODS: Patients scheduled for elective surgery of the upper (n = 23) or lower (n = 27) gastrointestinal tract participated in a prospective observational study. Patients' charateristics and nutritional status were recorded and blood samples were drawn on the day of admission. Further blood samples were collected before skin incision of the surgical procedure, on postoperative day 3 and on the day of discharge. Values of clinical chemistry, electrolytes, hemograms and plasma amino acids were determined and correlated with fasting times. RESULTS: Preoperative fasting times were positively correlated with plasma levels of valine, leucine, serine, alpha-amino butyric acid, free fatty acids, 3-hydroxy butyric acid and significantly negative correlated with chloride and glutamic acid. Postoperative fasting times were correlated with erythrocytes, leukocytes and plasma levels of albumin, CRP, HDL, asparagine and 3-methylhistidine. The multivariate regression analysis revealed glutamic acid and valine as significant independent predictors of preoperative fasting periods. The regression model showed best performance (sensitivity of 90.91% and specificity of 92.31%) to detect patients fasted for >/=20 h. CONCLUSION: Valine and glutamic acid appear as independent metabolic markers for accurate prediction of prolonged fasting periods, independent of the overall nutritional status, age or BMI of patients.

Authors: T. Wuensch, J. Quint, V. Mueller, A. Mueller, J. Wizenty, M. Kaffarnik, B. Kern, M. Stockmann, M. Biebl, J. Pratschke, F. Aigner

Date Published: 25th Mar 2019

Publication Type: Not specified

Predicting liver failure after extended right hepatectomy following right portal vein embolization with gadoxetic acid-enhanced MRI.

Abstract (Expand)

OBJECTIVES: Predicting post-hepatectomy liver failure (PHLF) after extended right hepatectomy following portal vein embolization (PVE) from serial gadoxetic acid-enhanced magnetic resonance imaging … (MRI). METHODS: Thirty-six patients who underwent hepatectomy following PVE were evaluated prospectively with gadoxetic acid-enhanced MRI examinations at predefined intervals during the course of their treatment, i.e., before and 14 days and 28 days after PVE as well as 10 days after hepatectomy. Relative enhancement (RE) and volume of the left and right liver lobes were determined. The study population was divided into two groups with respect to signs of PHLF. Differences between the two groups were assessed using the Mann-Whitney U test, and predictive parameters for group membership were investigated using ROC and logistic regression analysis. RESULTS: RE of the left lobe prior to PVE versus 14 days after PVE was significantly lower in patients with PHLF than in those without PHLF (Mann-Whitney U test p < 0.001) and proved to be the best predictor of PHLF in ROC analysis with an AUC of 0.854 (p < 0.001) and a cutoff value of - 0.044 with 75.0% sensitivity and 92.6% specificity. Consistent with this result, logistic linear regression analysis adjusted for age identified the same parameter to be a significant predictor of PHLF (p = 0.040). CONCLUSIONS: Gadoxetic acid-enhanced MRI performed as an imaging-based liver function test before and after PVE can help to predict PHLF. The risk of PHLF can be predicted as early as 14 days after PVE. KEY POINTS: * To predict the likelihood of post-hepatectomy liver failure, it is important to estimate not only future liver remnant volume prior to extended liver resection but also future liver remnant function. * Future liver remnant function can be predicted by performing gadoxetic acid-enhanced MRI as an imaging-based liver function test before and after portal vein embolization. * A reduction of relative enhancement of the liver in gadoxetic acid-enhanced MRI after portal vein embolization of 0.044 predicts post-hepatectomy liver failure with 75.0% sensitivity and 92.6% specificity.

Authors: D. Theilig, I. Steffen, M. Malinowski, M. Stockmann, D. Seehofer, J. Pratschke, B. Hamm, T. Denecke, D. Geisel

Date Published: 23rd Mar 2019

Publication Type: Not specified

Advanced liver function assessment in patients with intestinal failure on long-term parenteral nutrition.

Abstract (Expand)

BACKGROUND & AIMS: Intestinal failure associated liver disease (IFALD) is one of the leading complications and causes of deaths in adult patients receiving home parenteral nutrition for chronic … intestinal failure (CIF). Early diagnosis of IFALD is key to alleviate the progression of hepatic dysfunction. The aim of this study was to evaluate the capability of noninvasive liver function tests. METHODS: 90 adult patients with CIF receiving long-term home parenteral nutrition were included in a prospective cross-sectional study at our department between 2014 and 2017. All participants underwent dynamic liver function assessment (maximum liver function capacity [LiMAx] test, indocyanine green [ICG] test), transient elastography (FibroScan), blood tests and comprehensive nutritional status assessment. Univariate and multivariable analysis were performed to identify predictors of liver function. RESULTS: LiMAx, ICG test, and FibroScan highly correlated with standard liver function tests. Multivariable analysis identified intact ileum (B = 520.895; p = 0.010), digestive anatomy type 3 (B = 75.612; p = 0.025), citrulline level (B = 3.428; p = 0.040), parenteral olive oil intake (B = -0.570; p = 0.043), and oral intake (B = 182.227; p = 0.040) as independent risk factors affecting liver function determined by LiMAx test. ICG test and FibroScan showed no correlation with gastrointestinal and nutrition-related parameters. CONCLUSION: The LiMAx test is significantly associated with widely accepted risk factors for IFALD by multivariable analysis, whereas ICG test and FibroScan failed to show significant correlations. Liver function assessment by LiMAx test may therefore have the potential to detect alterations in liver function and identify patients at risk for the development of IFALD. Longitudinal studies are needed to investigate the impact of liver function determined by LiMAx test on long-term outcome in patients with CIF.

Authors: E. Bluthner, J. Bednarsch, U. F. Pape, M. Karber, S. Maasberg, U. A. Gerlach, A. Pascher, B. Wiedenmann, J. Pratschke, M. Stockmann

Date Published: 20th Mar 2019

Publication Type: Not specified

Hepatic CYP1A2 activity in liver tumors and the implications for preoperative volume-function analysis.

Abstract (Expand)

Dynamic liver function assessment by the (13)C-methacetin maximal liver function capacity (LiMAx) test reflects the overall hepatic CYP1A2 activity. One proven strategy for preoperative risk assessement … in liver surgery includes the combined assessment of the dynamic liver function by the LiMAx test, the volumetric analysis of the liver and calculation of future liver remnant function. This so-called volume-function analysis assumes that the remaining CYP1A2 activity in any tumor lesion is zero. The here presented study aims to assess the remaining CYP1A2 activities in different hepatic tumor lesions and its consequences for the preoperative volume-function analysis in patients undergoing liver surgery. The CYP1A2 activity analysis of neoplastic lesions and adjacent non-tumor liver tissue from resected tumor specimens revealed a significantly higher CYP1A2 activity (median, interquartile range) in non-tumor tissues (35.5, 15.9-54.4 microU/mg) as compared to hepatocellular adenomas (7.35, 1.2-32.5 microU/mg), hepatocellular carcinomas (0.18, 0.0-2.0 microU/mg) or colorectal liver metastasis (0.17, 0.0-2.1 microU/mg), respectively. In non-tumor liver tissue a gradual decline in CYP1A2 activity with exacerbating fibrosis was observed. The CYP1A2 activity differences were also reflected in CYP1A2 protein signals in the assessed hepatic tissues. Volume-function analysis showed a minimal deviation compared to the current standard calculation for hepatocellular carcinomas or colorectal liver metastasis (<1% difference), while a difference of 11.9% was observed for hepatocellular adenomas. These findings are important for a refined preoperative volume-function analysis and improved surgical risk assessment in hepatocellular adenoma cases with low LiMAx values.

Authors: T. Wuensch, N. Heucke, J. Wizenty, J. Quint, B. Sinn, R. Arsenic, M. Jara, M. Kaffarnik, J. Pratschke, M. Stockmann

Date Published: 14th Mar 2019

Publication Type: Not specified

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