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Hergo Holzhütter

About Hergo Holzhütter:
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SEEK ID: https://seek.lisym.org/people/54

Location:  Germany

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Related items

LiSyM-Krebs Partnering

This generic project is intended to be a forum for all LiSyM partner and external stakeholders interested in participating in the BMBF initiative LiSyM-Krebs.

Public web page: https://www.ptj.de/projektfoerderung/gesundheitsforschung/lisym-krebs

LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Disorders of the liver show up through changes in blood tests. These blood tests indicate markers for events taking place in the liver. Usually studies of liver tissue cannot be performed: as liver samples would need to be obtained through a liver biopsy, and this procedure is not without risk, therefore these samples are usually unavailable. Complex metabolism models based on existing and new scientific data can simulate changes in the liver caused by disease. They often reveal unknown relationships
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Public web page: http://www.lisym.org/our-work/pillar-research/the-liver-is-very-patient

Start date: 1st Jan 2016

Molecular Steatosis - Imaging & Modeling (LiSyM-MSIM)

Dr. Nachiket Vartak (TU University, Dortmund) investigates the role of a particular protein - the GTPase Rab18 - in initiating NAFLD. He tries to influence Rab18 pharmacologically so that NAFLD is not initiated. Vartak also analyzes how bile acids leave the liver. He hopes to find ways to improve the flow of bile in a liver with dysfunctional bile flow.

Public web page: http://www.lisym.org/our-work/junior-group/the-protein-rab18

Start date: 1st Jan 2016

LiSyM Scientific Leadership Team (LiSyM-LT)

Day-to-day science within the LiSyM is overseen and directed by the the LiSyM Scientific Leadership Team. This coordination team comprises the pillar coordinators and additional LiSyM members, and ensures smooth interaction between multi-skilled groups, often working in different institutions and across significant distances within Germany.

Public web page: http://www.lisym.org/who-we-are

LiSyM network

This comprises the whole LiSyM network

Public web page: http://www.lisym.org

Start date: 1st Jan 2016

Functional consequences of metabolic zonation in murine livers: New insights for an old story.
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract (Expand)

BACKGROUND & AIMS: Zone-dependent differences in the expression of metabolic enzymes along the porto-central axis of the acinus are a long-known feature of liver metabolism. A prominent example is … the preferential localization of the enzyme glutamine synthetase in pericentral hepatocytes, where it converts potentially toxic ammonia to the valuable amino acid glutamine. However, with the exception of a few key regulatory enzymes, a comprehensive and quantitative assessment of zonal differences in the abundance of metabolic enzymes and much more importantly, an estimation of the associated functional differences between portal and central hepatocytes is missing thus far. APPROACH & RESULTS: We addressed this problem by establishing a new method for the separation of periportal and pericentral hepatocytes that yields sufficiently pure fractions of both cell populations. Quantitative shotgun proteomics identified hundreds of differentially expressed enzymes in the two cell populations. We used zone-specific proteomics data for scaling of the maximal activities to generate portal and central instantiations of a comprehensive kinetic model of central hepatic metabolism (Hepatokin1). CONCLUSION: The model simulations revealed significant portal-to-central differences in almost all metabolic pathways involving carbohydrates, fatty acids, amino acids and detoxification.

Authors: N. Berndt, E. Kolbe, R. Gajowski, J. Eckstein, F. Ott, D. Meierhofer, H. G. Holzhutter, M. Matz-Soja

Date Published: 14th Apr 2020

Publication Type: Not specified

A novel variant of the (13)C-methacetin liver function breath test that eliminates the confounding effect of individual differences in systemic CO2 kinetics.
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract (Expand)

The principle of dynamic liver function breath tests is founded on the administration of a (13)C-labeled drug and subsequent monitoring of (13)CO2 in the breath, quantified as time series delta over … natural baseline (13)CO2 (DOB) liberated from the drug during hepatic CYP-dependent detoxification. One confounding factor limiting the diagnostic value of such tests is that only a fraction of the liberated (13)CO2 is immediately exhaled, while another fraction is taken up by body compartments from which it returns with delay to the plasma. The aims of this study were to establish a novel variant of the methacetin-based breath test LiMAx that allows to estimate and to eliminate the confounding effect of systemic (13)CO2 distribution on the DOB curve and thus enables a more reliable assessment of the hepatic detoxification capacity compared with the conventional LiMAx test. We designed a new test variant (named "2DOB") consisting of two consecutive phases. Phase 1 is initiated by the intravenous administration of (13)C-bicarbonate. Phase 2 starts about 30 min later with the intravenous administration of the (13)C-labelled test drug. Using compartment modelling, the resulting 2-phasic DOB curve yields the rate constants for the irreversible elimination and the reversible exchange of plasma (13)CO2 with body compartments (phase 1) and for the detoxification and exchange of the drug with body compartments (phase 2). We carried out the 2DOB test with the test drug (13)C-methacetin in 16 subjects with chronic liver pathologies and 22 normal subjects, who also underwent the conventional LiMAx test. Individual differences in the systemic CO2 kinetics can lead to deviations up to a factor of 2 in the maximum of DOB curves (coefficient of variation CV approximately 0.2) which, in particular, may hamper the discrimination between subjects with normal or mildly impaired detoxification capacities. The novel test revealed that a significant portion of the drug is not immediately metabolized, but transiently taken up into a storage compartment. Intriguingly, not only the hepatic detoxification rate but also the storage capacity of the drug, turned out to be indicative for a normal liver function. We thus used both parameters to define a scoring function which yielded an excellent disease classification (AUC = 0.95) and a high correlation with the MELD score (RSpearman = 0.92). The novel test variant 2DOB promises a significant improvement in the assessment of impaired hepatic detoxification capacity. The suitability of the test for the reliable characterization of the natural history of chronic liver diseases (fatty liver-fibrosis-cirrhosis) has to be assessed in further studies.

Authors: H. G. Holzhutter, T. Wuensch, R. Gajowski, N. Berndt, S. Bulik, D. Meierhofer, M. Stockmann

Date Published: 6th Feb 2020

Publication Type: Not specified

Kinetic modelling of quantitative proteome data predicts metabolic reprogramming of liver cancer
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract

Not specified

Authors: Nikolaus Berndt, Antje Egners, Guido Mastrobuoni, Olga Vvedenskaya, Athanassios Fragoulis, Aurélien Dugourd, Sascha Bulik, Matthias Pietzke, Chris Bielow, Rob van Gassel, Steven W. Olde Damink, Merve Erdem, Julio Saez-Rodriguez, Hermann-Georg Holzhütter, Stefan Kempa, Thorsten Cramer

Date Published: 10th Dec 2019

Publication Type: Not specified

Metabolic modelling of kidney diseases: Lessons learned from the liver
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract

Not specified

Authors: Nikolaus Berndt, Andreas Patzak, Hermann‐Georg Holzhütter

Date Published: 9th Aug 2019

Publication Type: Not specified

Characterization of Lipid and Lipid Droplet Metabolism in Human HCC.
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

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

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