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6 Publications matching the given criteria: (Clear all filters)
Author: Lars Kuepfer6
Bile micro-infarcts in cholestasis are initiated by rupture of the apical hepatocyte membrane and cause shunting of bile to sinusoidal blood

Abstract

Not specified

Authors: Ahmed Ghallab, Ute Hofmann, Selahaddin Sezgin, Nachiket Vartak, Reham Hassan, Ayham Zaza, Patricio Godoy, Kai Markus Schneider, Georgia Guenther, Yasser A Ahmed, Aya A Abbas, Verena Keitel, Lars Kuepfer, Steven Dooley, Frank Lammert, Christian Trautwein, Michael Spiteller, Dirk Drasdo, Alan F Hofmann, Peter L M Jansen, Jan G Hengstler, Raymond Reif

Date Published: 13th Aug 2018

Publication Type: Not specified

Spatio-temporal visualization of the distribution of acetaminophen as well as its metabolites and adducts in mouse livers by MALDI MSI

Abstract (Expand)

Acetaminophen (APAP) is one of the most intensively studied compounds that causes hepatotoxicity in the pericentral region of the liver lobules. However, spatio-temporal information on the distribution … of APAP, its metabolites and GSH adducts in the liver tissue is not yet available. Here, we addressed the question, whether APAP-GSH adducts and GSH depletion show a zonated pattern and whether the distribution of APAP and its glucuronide as well as sulfate conjugates in liver lobules are zonated. For this purpose, a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) technique was established, where the MSI images were superimposed onto CYP2E1 immunostained tissue. A time-dependent analysis (5, 15, 30, 60, 120, 240, 480 min) after intraperitoneal administration of 300 mg/kg APAP and a dose-dependent analysis (56 up to 500 mg APAP/kg) at 30 min were performed. The results demonstrate that the MALDI MSI technique allows the assignment of compounds and their metabolites to specific lobular zones. APAP-GSH adducts and GSH depletion occurred predominantly in the CYP2E1-positive zone of the liver, although GSH also decreased in the periportal region. In contrast, the parent compound, APAP sulfate and APAP glucuronide did not show a zonated pattern and tissue concentrations showed a similar time course as the corresponding analyses were performed with blood from the portal and liver veins. In conclusion, the present study is in agreement with the concept that pericentral CYPs form NAPQI that in the same cell binds to and depletes GSH but a lower level of GSH adducts is also observed in the periportal region. The results also provide further evidence of the recently published concept of 'aggravated loss of clearance capacity' according to which also liver tissue that survives intoxication may transiently show decreased metabolic capacity.

Authors: Selahaddin Sezgin, Reham Hassan, Sebastian Zühlke, Lars Kuepfer, Jan G. Hengstler, Michael Spiteller, Ahmed Ghallab

Date Published: 23rd Jul 2018

Publication Type: Not specified

Physiologically-based modelling in mice suggests an aggravated loss of clearance capacity after toxic liver damage

Abstract

Not specified

Authors: Arne Schenk, Ahmed Ghallab, Ute Hofmann, Reham Hassan, Michael Schwarz, Andreas Schuppert, Lars Ole Schwen, Albert Braeuning, Donato Teutonico, Jan G. Hengstler, Lars Kuepfer

Date Published: 1st Dec 2017

Publication Type: Not specified

Towards knowledge-driven cross-species extrapolation

Abstract

Not specified

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

Date Published: 1st Apr 2017

Publication Type: Not specified

In vivo imaging of systemic transport and elimination of xenobiotics and endogenous molecules in mice

Abstract (Expand)

We describe a two-photon microscopy-based method to evaluate the in vivo systemic transport of compounds. This method comprises imaging of the intact liver, kidney and intestine, the main organs …gans responsible for uptake and elimination of xenobiotics and endogenous molecules. The image quality of the acquired movies was sufficient to distinguish subcellular structures like organelles and vesicles. Quantification of the movement of fluorescent dextran and fluorescent cholic acid derivatives in different organs and their sub-compartments over time revealed significant dynamic differences. Calculated half-lives were similar in the capillaries of all investigated organs but differed in the specific sub-compartments, such as parenchymal cells and bile canaliculi of the liver, glomeruli, proximal and distal tubules of the kidney and lymph vessels (lacteals) of the small intestine. Moreover, tools to image immune cells, which can influence transport processes in inflamed tissues, are described. This powerful approach provides new possibilities for the analysis of compound transport in multiple organs and can support physiologically based pharmacokinetic modeling, in order to obtain more precise predictions at the whole body scale.

Authors: Raymond Reif, Ahmed Ghallab, Lynette Beattie, Georgia Günther, Lars Kuepfer, Paul M. Kaye, Jan G. Hengstler

Date Published: 1st Mar 2017

Publication Type: Not specified

Model-guided identification of a therapeutic strategy to reduce hyperammonemia in liver diseases

Abstract (Expand)

BACKGROUND & AIMS: Recently, spatial-temporal/metabolic mathematical models have been established that allow the simulation of metabolic processes in tissues. We applied these models to decipher …er ammonia detoxification mechanisms in the liver. METHODS: An integrated metabolic-spatial-temporal model was used to generate hypotheses of ammonia metabolism. Predicted mechanisms were validated using time-resolved analyses of nitrogen metabolism, activity analyses, immunostaining and gene expression after induction of liver damage in mice. Moreover, blood from the portal vein, liver vein and mixed venous blood was analyzed in a time dependent manner. RESULTS: Modeling revealed an underestimation of ammonia consumption after liver damage when only the currently established mechanisms of ammonia detoxification were simulated. By iterative cycles of modeling and experiments, the reductive amidation of alpha-ketoglutarate (α-KG) via glutamate dehydrogenase (GDH) was identified as the lacking component. GDH is released from damaged hepatocytes into the blood where it consumes ammonia to generate glutamate, thereby providing systemic protection against hyperammonemia. This mechanism was exploited therapeutically in a mouse model of hyperammonemia by injecting GDH together with optimized doses of cofactors. Intravenous injection of GDH (720 U/kg), α-KG (280 mg/kg) and NADPH (180 mg/kg) reduced the elevated blood ammonia concentrations (>200 μM) to levels close to normal within only 15 min. CONCLUSION: If successfully translated to patients the GDH-based therapy might provide a less aggressive therapeutic alternative for patients with severe hyperammonemia.

Authors: Ahmed Ghallab, Géraldine Cellière, Sebastian G. Henkel, Dominik Driesch, Stefan Hoehme, Ute Hofmann, Sebastian Zellmer, Patricio Godoy, Agapios Sachinidis, Meinolf Blaszkewicz, Raymond Reif, Rosemarie Marchan, Lars Kuepfer, Dieter Häussinger, Dirk Drasdo, Rolf Gebhardt, Jan G. Hengstler

Date Published: 1st Apr 2016

Publication Type: Not specified

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