1
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Ebner J, Schmoellerl J, Piontek M, Manhart G, Troester S, Carter BZ, Neubauer H, Moriggl R, Szakács G, Zuber J, Köcher T, Andreeff M, Sperr WR, Valent P, Grebien F. ABCC1 and glutathione metabolism limit the efficacy of BCL-2 inhibitors in acute myeloid leukemia. Nat Commun 2023; 14:5709. [PMID: 37726279 PMCID: PMC10509209 DOI: 10.1038/s41467-023-41229-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 08/25/2023] [Indexed: 09/21/2023] Open
Abstract
The BCL-2 inhibitor Venetoclax is a promising agent for the treatment of acute myeloid leukemia (AML). However, many patients are refractory to Venetoclax, and resistance develops quickly. ATP-binding cassette (ABC) transporters mediate chemotherapy resistance but their role in modulating the activity of targeted small-molecule inhibitors is unclear. Using CRISPR/Cas9 screening, we find that loss of ABCC1 strongly increases the sensitivity of AML cells to Venetoclax. Genetic and pharmacologic ABCC1 inactivation potentiates the anti-leukemic effects of BCL-2 inhibitors and efficiently re-sensitizes Venetoclax-resistant leukemia cells. Conversely, ABCC1 overexpression induces resistance to BCL-2 inhibitors by reducing intracellular drug levels, and high ABCC1 levels predicts poor response to Venetoclax therapy in patients. Consistent with ABCC1-specific export of glutathionylated substrates, inhibition of glutathione metabolism increases the potency of BCL-2 inhibitors. These results identify ABCC1 and glutathione metabolism as mechanisms limiting efficacy of BCL-2 inhibitors, which may pave the way to development of more effective therapies.
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Affiliation(s)
- Jessica Ebner
- Institute for Medical Biochemistry, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Johannes Schmoellerl
- Institute for Medical Biochemistry, University of Veterinary Medicine Vienna, Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
| | - Martin Piontek
- Institute for Medical Biochemistry, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Gabriele Manhart
- Institute for Medical Biochemistry, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Selina Troester
- Institute for Medical Biochemistry, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Bing Z Carter
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Heidi Neubauer
- Institute for Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Richard Moriggl
- Institute for Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Gergely Szakács
- Center for Cancer Research, Medical University Vienna, Vienna, Austria
- Institute of Enzymology, Research Centre of Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
| | - Johannes Zuber
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
- Medical University of Vienna, Vienna, Austria
| | - Thomas Köcher
- Vienna BioCenter Core Facilities, Vienna BioCenter, Vienna, Austria
| | - Michael Andreeff
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Wolfgang R Sperr
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna, Vienna, Austria
| | - Peter Valent
- Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna, Vienna, Austria
| | - Florian Grebien
- Institute for Medical Biochemistry, University of Veterinary Medicine Vienna, Vienna, Austria.
- St. Anna Children's Cancer Research Institute (CCRI), Vienna, Austria.
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2
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Kiss A, Szabo PL, Ebner J, Hilber K, Abraham D, Costantino S, Paneni F, Nikhanj A, Kashyap N, Ouadit GY, Podesser BK. Increased Tenascin-C expression contributes to cardiac dysfunction and fibrosis in Duchenne muscular dystrophy. Eur Heart J 2022. [DOI: 10.1093/eurheartj/ehac544.2986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Introduction and aims
Cardiac fibrosis is characterized by the net accumulation of extracellular matrix (ECM) proteins in the cardiac interstitium and contributes to cardiac contractile dysfunction. In Duchenne muscular dystrophy (DMD), cardiomyopathy develops as a result of a dystrophin deficiency causing fibrofatty replacement of the myocardium, however the underlying mechanisms are not fully understood. There is a growing collection of evidence that ECM proteins, including Tenascin C (TN-C), plays a maladaptive role in left ventricular (LV) remodelling and cardiac fibrosis in ischemic heart disease. The aims of our study were 1) to assess TN-C levels, fibrosis and cardiac dysfunction in DMD patients, and 2) to clarify the role of TN-C in cardiovascular dysfunction and fibrosis using male mdx (n=10) and mdx TN-C KO mice (n=8).
Results
In male patients with DMD (n=18) and age matched controls (n=12) undergoing cardiac MRI, we detected greater myocardial fibrosis than in control hearts. In addition, we observed an elevation of TN-C plasma levels [median concentration (3.55); interquartile range (0.61–7.43) ng/mL] in DMD patients, and its expression negatively correlated to LV ejection fraction (EF) [median LVEF (45); interquartile range (37.5–51.5) %]. Male wt, mdx and mdx TN-C KO age-matched (10 months) mice were used. Transthoracic echocardiography was performed and fibrosis was assessed on cardiac tissue sections. Wire myography was used to assess vascular endothelial function. To explore the signalling pathways contributing to cardiac fibrosis, human cardiac fibroblasts (hCFs) were treated with recombinant human TN-C or TGF-β and gene expression and epigenetic regulation of NF-kB/p65 were assessed. Mdx mice showed significantly increased cardiac fibrosis which was accompanied with markedly elevated TN-C level in cardiac tissue and plasma compared to wt animals (p<0.05, respectively). Moreover, TN-C level in plasma correlated positively with the degree of cardiac dilation in dystrophic mice. In addition, vascular endothelial function was notably impaired in mdx mice. In contrast, we observed preserved vascular function in mdx- TN-C KO mice, this was accompanied by a significant reduction in cardiac fibrosis in compared to age-matched mdx mice (p<0.05, respectively). hCFs treated with TN-C or TGF-β showed increased collagen and α-SMA expressions which could be prevented by application of siRNA against TN-C. In addition, both TN-C and TGF-β caused p65/NF-κB promoter demethylation and subsequently triggered pro-inflammatory and pro-fibrotic signalling, which could be reversed by applying p38 MAPK inhibitor in hCFs.
Conclusion
TN-C is a critical component of cardiac fibrosis and cardiac dysfunction in DMD. The activation of NF-κB p65 signalling pathway may play a role in TN-C induced fibrosis. Thus, TN-C may be a mediator and potential target for therapy in DMD-associated cardiovascular complications.
Funding Acknowledgement
Type of funding sources: Foundation. Main funding source(s): Österreichische MuskelforschungFWF - Austrian Science Found P 35878
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Affiliation(s)
- A Kiss
- Medical University of Vienna , Vienna , Austria
| | - P L Szabo
- Medical University of Vienna, Center for Biomedical Research , Vienna , Austria
| | - J Ebner
- Medical University of Vienna, Center for Physiology and Pharmacology , Vienna , Austria
| | - K Hilber
- Medical University of Vienna, Center for Physiology and Pharmacology , Vienna , Austria
| | - D Abraham
- Medical University of Vienna, Center for Anatomy and Cell Biology, Division of Cell and Developmental Biology , Vienna , Austria
| | - S Costantino
- University of Zurich and University Heart Center, Center for Molecular Cardiology, , Zurich , Switzerland
| | - F Paneni
- University of Zurich and University Heart Center, Center for Molecular Cardiology, , Zurich , Switzerland
| | - A Nikhanj
- Mazankowski Alberta Heart Institute, Department of Medicine, Faculty of Medicine and Dentistry, Uni, Division of Cardiology , Edmonton , Canada
| | - N Kashyap
- Mazankowski Alberta Heart Institute, Department of Medicine, Faculty of Medicine and Dentistry, Uni, Division of Cardiology , Edmonton , Canada
| | - G Y Ouadit
- Mazankowski Alberta Heart Institute, Department of Medicine, Faculty of Medicine and Dentistry, Uni, Division of Cardiology , Edmonton , Canada
| | - B K Podesser
- Medical University of Vienna, Center for Biomedical Research , Vienna , Austria
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3
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Bajusz D, Bognár Z, Ebner J, Grebien F, Keserű GM. Discovery of a Non-Nucleoside SETD2 Methyltransferase Inhibitor against Acute Myeloid Leukemia. Int J Mol Sci 2021; 22:ijms221810055. [PMID: 34576219 PMCID: PMC8471172 DOI: 10.3390/ijms221810055] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/06/2021] [Accepted: 09/13/2021] [Indexed: 11/16/2022] Open
Abstract
Histone methyltransferases (HMTs) have attracted considerable attention as potential targets for pharmaceutical intervention in various malignant diseases. These enzymes are known for introducing methyl marks at specific locations of histone proteins, creating a complex system that regulates epigenetic control of gene expression and cell differentiation. Here, we describe the identification of first-generation cell-permeable non-nucleoside type inhibitors of SETD2, the only mammalian HMT that is able to tri-methylate the K36 residue of histone H3. By generating the epigenetic mark H3K36me3, SETD2 is involved in the progression of acute myeloid leukemia. We developed a structure-based virtual screening protocol that was first validated in retrospective studies. Next, prospective screening was performed on a large library of commercially available compounds. Experimental validation of 22 virtual hits led to the discovery of three compounds that showed dose-dependent inhibition of the enzymatic activity of SETD2. Compound C13 effectively blocked the proliferation of two acute myeloid leukemia (AML) cell lines with MLL rearrangements and led to decreased H3K36me3 levels, prioritizing this chemotype as a viable chemical starting point for drug discovery projects.
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Affiliation(s)
- Dávid Bajusz
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, 1117 Budapest, Hungary; (D.B.); (Z.B.)
| | - Zsolt Bognár
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, 1117 Budapest, Hungary; (D.B.); (Z.B.)
| | - Jessica Ebner
- Institute for Medical Biochemistry, University of Veterinary Medicine, 1220 Vienna, Austria; (J.E.); (F.G.)
| | - Florian Grebien
- Institute for Medical Biochemistry, University of Veterinary Medicine, 1220 Vienna, Austria; (J.E.); (F.G.)
| | - György M. Keserű
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, 1117 Budapest, Hungary; (D.B.); (Z.B.)
- Correspondence:
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4
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Bajusz D, Wade WS, Satała G, Bojarski AJ, Ilaš J, Ebner J, Grebien F, Papp H, Jakab F, Douangamath A, Fearon D, von Delft F, Schuller M, Ahel I, Wakefield A, Vajda S, Gerencsér J, Pallai P, Keserű GM. Exploring protein hotspots by optimized fragment pharmacophores. Nat Commun 2021; 12:3201. [PMID: 34045440 PMCID: PMC8159961 DOI: 10.1038/s41467-021-23443-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 04/29/2021] [Indexed: 02/04/2023] Open
Abstract
Fragment-based drug design has introduced a bottom-up process for drug development, with improved sampling of chemical space and increased effectiveness in early drug discovery. Here, we combine the use of pharmacophores, the most general concept of representing drug-target interactions with the theory of protein hotspots, to develop a design protocol for fragment libraries. The SpotXplorer approach compiles small fragment libraries that maximize the coverage of experimentally confirmed binding pharmacophores at the most preferred hotspots. The efficiency of this approach is demonstrated with a pilot library of 96 fragment-sized compounds (SpotXplorer0) that is validated on popular target classes and emerging drug targets. Biochemical screening against a set of GPCRs and proteases retrieves compounds containing an average of 70% of known pharmacophores for these targets. More importantly, SpotXplorer0 screening identifies confirmed hits against recently established challenging targets such as the histone methyltransferase SETD2, the main protease (3CLPro) and the NSP3 macrodomain of SARS-CoV-2.
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Affiliation(s)
- Dávid Bajusz
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, Budapest, Hungary
| | | | - Grzegorz Satała
- Maj Institute of Pharmacology Polish Academy of Sciences, Kraków, Poland
| | - Andrzej J Bojarski
- Maj Institute of Pharmacology Polish Academy of Sciences, Kraków, Poland
| | - Janez Ilaš
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Jessica Ebner
- Institute for Medical Biochemistry, University of Veterinary Medicine, Vienna, Austria
| | - Florian Grebien
- Institute for Medical Biochemistry, University of Veterinary Medicine, Vienna, Austria
| | - Henrietta Papp
- National Laboratory of Virology, Szentágothai Research Centre, University of Pécs, Pécs, Hungary
| | - Ferenc Jakab
- National Laboratory of Virology, Szentágothai Research Centre, University of Pécs, Pécs, Hungary
| | - Alice Douangamath
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA, UK
| | - Daren Fearon
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA, UK
| | - Frank von Delft
- Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, UK
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0FA, UK
- Structural Genomics Consortium, University of Oxford, Old Road Campus, Roosevelt Drive, Headington, OX3 7DQ, UK
- Centre for Medicines Discovery, University of Oxford, Old Road Campus, Roosevelt Drive, Headington, OX3 7DQ, UK
- Department of Biochemistry, University of Johannesburg, Auckland Park, 2006, South Africa
| | - Marion Schuller
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Ivan Ahel
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Amanda Wakefield
- Department of Chemistry, Boston University, Boston, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sándor Vajda
- Department of Chemistry, Boston University, Boston, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | | | | | - György M Keserű
- Medicinal Chemistry Research Group, Research Centre for Natural Sciences, Budapest, Hungary.
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5
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Szabo P, Hamza O, Inci M, Ebner J, Hilber K, Dietmar A, Trojanek S, Podesser B, Kiss A. Presence of Tenascin-C accompanied by cardiac and vascular dysfunction in a mouse model of Duchenne muscular dystrophy. Atherosclerosis 2020. [DOI: 10.1016/j.atherosclerosis.2020.10.271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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6
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Szabó P, Hamza O, Milat I, Hilber K, Ebner J, Podesser B, Kiss A. Progression Of Cardiac And Vascular Dysfunction In Mouse Model Of Duchenne Muscular Dystrophy. Atherosclerosis 2019. [DOI: 10.1016/j.atherosclerosis.2019.06.838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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7
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Skucha A, Ebner J, Grebien F. Roles of SETD2 in Leukemia-Transcription, DNA-Damage, and Beyond. Int J Mol Sci 2019; 20:ijms20051029. [PMID: 30818762 PMCID: PMC6429614 DOI: 10.3390/ijms20051029] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/15/2019] [Accepted: 02/20/2019] [Indexed: 01/07/2023] Open
Abstract
The non-redundant histone methyltransferase SETD2 (SET domain containing 2; KMT3A) is responsible for tri-methylation of lysine 36 on histone H3 (H3K36me3). Presence of the H3K36me3 histone mark across the genome has been correlated with transcriptional activation and elongation, but also with the regulation of DNA mismatch repair, homologous recombination and alternative splicing. The role of SETD2 and the H3K36me3 histone mark in cancer is controversial. SETD2 is lost or mutated in various cancers, supporting a tumor suppressive role of the protein. Alterations in the SETD2 gene are also present in leukemia patients, where they are associated with aggressive disease and relapse. In line, heterozygous SETD2 loss caused chemotherapy resistance in leukemia cell lines and mouse models. In contrast, other studies indicate that SETD2 is critically required for the proliferation of leukemia cells. Thus, although studies of SETD2-dependent processes in cancer have contributed to a better understanding of the SETD2⁻H3K36me3 axis, many open questions remain regarding its specific role in leukemia. Here, we review the current literature about critical functions of SETD2 in the context of hematopoietic malignancies.
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Affiliation(s)
- Anna Skucha
- CeMM-Research Center for Molecular Medicine of the Austrian Academy of Sciences, Lazarettgasse 14, AKH BT 25.3, 1090 Vienna, Austria.
| | - Jessica Ebner
- Ludwig Boltzmann Institute for Cancer Research, Waehringer Strasse 13A, 1090 Vienna, Austria.
| | - Florian Grebien
- Ludwig Boltzmann Institute for Cancer Research, Waehringer Strasse 13A, 1090 Vienna, Austria.
- Institute for Medical Biochemistry, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
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8
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Skucha A, Ebner J, Grebien F. SETD2 in MLL-rearranged leukemia - a complex case. Mol Cell Oncol 2018; 5:e1503492. [PMID: 30250934 DOI: 10.1080/23723556.2018.1503492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 07/17/2018] [Accepted: 07/19/2018] [Indexed: 10/28/2022]
Abstract
Oncogenic MLL-fusion proteins often hijack essential molecular mechanisms during leukemogenesis. The histone methyltransferase SETD2 was implicated in the regulation of transcription, DNA damage and other cellular processes. Recent studies identified a critical role for SETD2 in MLL-rearranged leukemia. These results may help to unravel important functions of SETD2 in hematopoiesis.
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Affiliation(s)
- Anna Skucha
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.,Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria
| | - Jessica Ebner
- Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria
| | - Florian Grebien
- Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria.,Institute for Medical Biochemistry, University of Veterinary Medicine Vienna, Austria
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9
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Muendlein A, Ebner J, Leiherer A, Saely C, Geiger K, Brandtner E, Zanolin D, Vonbank A, Mader A, Larcher B, Fraunberger P, Drexel H. Evaluation of the association of single nucleotide polymorphisms in the sodium glucose co-transporter 2 gene with glucose homeostasis and type 2 diabetes. Atherosclerosis 2018. [DOI: 10.1016/j.atherosclerosis.2018.06.566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Leiherer A, Muendlein A, Geiger K, Saely CH, Brandtner EM, Ebner J, Larcher B, Mader A, Fraunberger P, Drexel H. P4768Targeted metabolomics identifies elevated serotonin levels in carriers of a TCF7L2 diabetes-risk allele. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy563.p4768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- A Leiherer
- Private University of the Principality of Liechtenstein, Triesen, Liechtenstein
| | | | - K Geiger
- VIVIT Institute, Feldkirch, Austria
| | - C H Saely
- Bern University Hospital, Division of Angiology, Swiss Cardiovascular Center, Bern, Switzerland
| | | | - J Ebner
- VIVIT Institute, Feldkirch, Austria
| | - B Larcher
- Academic Teaching Hospital, Department of Medicine and Cardiology, Feldkirch, Austria
| | - A Mader
- Academic Teaching Hospital, Department of Medicine and Cardiology, Feldkirch, Austria
| | - P Fraunberger
- Academic Teaching Hospital, Medical Central Laboratory Feldkirch, Feldkirch, Austria
| | - H Drexel
- Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
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11
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Muendlein A, Geiger K, Leiherer A, Saely C, Ebner J, Brandtner E, Zanolin D, Vonbank A, Mader A, Larcher B, Fraunberger P, Drexel H. Correlation between circulating micrornas and chronic kidney disease in patients with and without type 2 diabetes. Atherosclerosis 2018. [DOI: 10.1016/j.atherosclerosis.2018.06.576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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12
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Leiherer A, Muendlein A, Saely C, Ebner J, Brandtner E, Mader A, Larcher B, Fraunberger P, Drexel H. Serum uromodulin predicts mortality independently from the presence of type 2 diabetes. Atherosclerosis 2018. [DOI: 10.1016/j.atherosclerosis.2018.06.626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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13
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Manninger M, Ebner J, Zweiker D, Sieghartsleitner R, Mastnak B, Bisping E, Lercher P, Riedlbauer R, Rotman B, Brussee H, Scherr D. P6613Is there a difference in outcome in patients undergoing first vs. second line ablation of atrial fibrillation? Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy566.p6613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- M Manninger
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | - J Ebner
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | - D Zweiker
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | | | - B Mastnak
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | - E Bisping
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | - P Lercher
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | - R Riedlbauer
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | - B Rotman
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | - H Brussee
- Medical University of Graz, Department of Cardiology, Graz, Austria
| | - D Scherr
- Medical University of Graz, Department of Cardiology, Graz, Austria
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14
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Skucha A, Ebner J, Schmöllerl J, Roth M, Eder T, César-Razquin A, Stukalov A, Vittori S, Muhar M, Lu B, Aichinger M, Jude J, Müller AC, Győrffy B, Vakoc CR, Valent P, Bennett KL, Zuber J, Superti-Furga G, Grebien F. MLL-fusion-driven leukemia requires SETD2 to safeguard genomic integrity. Nat Commun 2018; 9:1983. [PMID: 29777171 PMCID: PMC5959866 DOI: 10.1038/s41467-018-04329-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 04/23/2018] [Indexed: 12/21/2022] Open
Abstract
MLL-fusions represent a large group of leukemia drivers, whose diversity originates from the vast molecular heterogeneity of C-terminal fusion partners of MLL. While studies of selected MLL-fusions have revealed critical molecular pathways, unifying mechanisms across all MLL-fusions remain poorly understood. We present the first comprehensive survey of protein-protein interactions of seven distantly related MLL-fusion proteins. Functional investigation of 128 conserved MLL-fusion-interactors identifies a specific role for the lysine methyltransferase SETD2 in MLL-leukemia. SETD2 loss causes growth arrest and differentiation of AML cells, and leads to increased DNA damage. In addition to its role in H3K36 tri-methylation, SETD2 is required to maintain high H3K79 di-methylation and MLL-AF9-binding to critical target genes, such as Hoxa9. SETD2 loss synergizes with pharmacologic inhibition of the H3K79 methyltransferase DOT1L to induce DNA damage, growth arrest, differentiation, and apoptosis. These results uncover a dependency for SETD2 during MLL-leukemogenesis, revealing a novel actionable vulnerability in this disease.
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Affiliation(s)
- Anna Skucha
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
- Ludwig Boltzmann Institute for Cancer Research, Vienna, 1090, Austria
| | - Jessica Ebner
- Ludwig Boltzmann Institute for Cancer Research, Vienna, 1090, Austria
| | | | - Mareike Roth
- Research Institute of Molecular Pathology, Vienna, 1030, Austria
| | - Thomas Eder
- Ludwig Boltzmann Institute for Cancer Research, Vienna, 1090, Austria
| | - Adrián César-Razquin
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
| | - Alexey Stukalov
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
| | - Sarah Vittori
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
| | - Matthias Muhar
- Research Institute of Molecular Pathology, Vienna, 1030, Austria
| | - Bin Lu
- Cold Spring Harbor Larboratory, Cold Spring Harbor, 11724, NY, USA
| | - Martin Aichinger
- Research Institute of Molecular Pathology, Vienna, 1030, Austria
| | - Julian Jude
- Research Institute of Molecular Pathology, Vienna, 1030, Austria
| | - André C Müller
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
| | - Balázs Győrffy
- MTA TTK Lendület Cancer Biomarker Research Group, Institute of Enzymology, Second Department of Pediatrics, Semmelweis University, Budapest, 1094, Hungary
| | | | - Peter Valent
- Department of Internal Medicine I. Division of Hematology and Hemostaseology, Ludwig Boltzmann Cluster Oncology, Medical University of Vienna, Vienna, 1090, Austria
| | - Keiryn L Bennett
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
| | - Johannes Zuber
- Research Institute of Molecular Pathology, Vienna, 1030, Austria
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, 1090, Austria
| | - Florian Grebien
- Ludwig Boltzmann Institute for Cancer Research, Vienna, 1090, Austria.
- Institute for Medical Biochemistry, University of Veterinary Medicine, Vienna, 1210, Austria.
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15
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Leiherer A, Muendlein A, Saely C, Ebner J, Brandtner E, Schuler A, Schwerzler P, Mader A, Fraunberger P, Drexel H. P6222Serum uromodulin predicts mortality independently from the presence of type 2 diabetes. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx493.p6222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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16
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Leiherer A, Muendlein A, Saely C, Ebner J, Brandtner E, Schuler A, Schwerzler P, Mader A, Fraunberger P, Drexel H. P6220The creatinine to uromodulin ratio in serum predicts major cardiovascular events independently from the presence of type 2 diabetes. Eur Heart J 2017. [DOI: 10.1093/eurheartj/ehx493.p6220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Manninger M, Zweiker D, Ebner J, Sieghartsleitner R, Ohnewein B, Brussee H, Scherr D. P913Is there a difference in outcome in patients undergoing first vs. second line ablation of atrial fibrillation? Europace 2017. [DOI: 10.1093/ehjci/eux151.095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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18
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Zweiker D, Manninger M, Ebner J, Sieghartsleitner R, Ohnewein B, Brussee H, Scherr D. P369Impact of non-VKA oral anticoagulants on AF ablation outcome. Europace 2017. [DOI: 10.1093/ehjci/eux141.095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Baumgartner C, Koenighaus H, Ebner J, Henke J, Schuster T, Erhardt W. Comparison of dipyrone/propofol versus fentanyl/propofol anaesthesia during surgery in rabbits. Lab Anim 2011; 45:38-44. [DOI: 10.1258/la.2010.010091] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this study, the investigation of the intraoperative effects of dipyrone (metamizol) on heart rate (HR), mean arterial pressure (MAP) and analgesic efficacy in rabbits is described for the first time. This was carried out to evaluate the cardiovascular stability achieved using dipyrone compared with fentanyl. In this prospective study, 17 female New Zealand White rabbits were randomly allocated to either one of two groups: dipyrone/propofol (DP) or fentanyl/propofol (FP). Anaesthesia was induced in both groups using propofol to effect (4.0–8.0 mg/kg intravenously) until the swallowing reflex was lost for intubation. After induction, anaesthesia was maintained with continuous infusion of propofol 1.5–1.7 mg/kg/min intravenously. Analgesics were then injected in defined boluses of either dipyrone 65 mg/kg or fentanyl 0.0053 mg/kg. After surgical tolerance, defined as loss of the ear pinch reflex and loss of the anterior and posterior pedal withdrawal reflex, was achieved, two surgical procedures were performed. The surgical procedures (implantation of either a pacemaker or an electrocardiogram transmitter), both require a comparable level of analgesic depth. During and after surgery, clinical variables, such as MAP, HR, peripheral arterial oxygen saturation (SpO2) and end-tidal CO2 (Pe′CO2) were recorded simultaneously every 2 min. Eight time points were chosen for comparison: baseline, surgical tolerance (ST), values at 10, 20 and 30 min after reaching ST, values at the end of propofol infusion (EI) and data at 10 and 20 min after EI. Both FP and DP combinations provided effective anaesthesia and analgesia in rabbits. In both groups a significant decrease of HR and MAP was measured. The results of this study indicate that the non-opioid drug dipyrone produces similar analgesic and even better cardiovascular effects by trend in rabbits. Therefore we conclude that dipyrone in combination with propofol can be used as an alternative to FP for intraoperative analgesia.
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Affiliation(s)
- C Baumgartner
- Centre of Preclinical Research, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
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20
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Redlberger A, Ardelean M, Ebner J, Emesz M. Multizystischer Orbitatumor mit Bulbusverdrängung. Ophthalmologe 2008; 105:949-51. [DOI: 10.1007/s00347-008-1725-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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21
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Ebner J, Wehr U, Baumgartner C, Erhardt W, Henke J. Partial Antagonization of Midazolam-Medetomidine-Ketamine in Cats – Atipamezole versus combined Atipamezole and Flumazenil. ACTA ACUST UNITED AC 2007; 54:518-21. [DOI: 10.1111/j.1439-0442.2007.00971.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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Ebner J, Wehr U, Busch R, Erhardt W, Henke J. A Comparative Clinical Study of Three Different Dosages of Intramuscular Midazolam?Medetomidine?Ketamine Immobilization in Cats. ACTA ACUST UNITED AC 2007; 54:418-23. [PMID: 17877583 DOI: 10.1111/j.1439-0442.2007.00943.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A low dose of midazolam-medetomidine-ketamine (MMK) combination was evaluated in three increasing dosages. Each of the 18 cats was randomly allocated for several times to one of four groups. Five minutes after premedication with intramuscular (IM) 0.04 mg/kg atropine, group A (n = 43), B (n = 40) and C (n = 28) all were anaesthetized with 0.5 mg/kg midazolam, combined with 10, 20 or 30 microg/kg medetomidine, and 1.0, 2.0 or 3.0 mg/kg ketamine, respectively, IM in one syringe. Group D (n = 11) received the established combination of 50 microg/kg medetomidine and 10.0 mg/kg ketamine for comparison. Because this study was in cooperation with a project on dental prophylaxis, cats had to be immobilized for approximately 1 h. Therefore, anaesthesia was prolonged with propofol to effect, if necessary. Duration of MMK anaesthesia was between 30 +/- 15, 45 +/- 19 and 68 +/- 28 min in groups A, B and C respectively. A significant decrease of respiratory rate was observed with increasing dosage, but venous carbon dioxide (pCO(2)) and pH values in combination with arterial oxygen saturation (SpO(2)) values were not alarming. The diastolic blood pressure particularly showed an increase. MMK combination A showed the best cardiovascular results, but it cannot be recommended due to disadvantages like a long induction time sometimes accompanied by excitations and the short duration of surgical immobilization. Dosage C in contrast had fewer side effects but less favourable cardiovascular results and a longer recovery period. However, either dosage B or C was suitable as a repeatable IM immobilization method for non-invasive procedures in healthy cats.
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Affiliation(s)
- J Ebner
- Centre of Preclinical Research, Klinikum rechts der Isar, Technical University, Ismaninger Str. 22, 81675 Munich, Germany.
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23
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Colton R, Ebner J, Hoskins BF. Multinuclear magnetic resonance studies of the reactions of bidentate ligands with platinum(2+) O,O'-diethyl dithiophosphate. Crystal and molecular structure of [(diphenylarsinoethyl)diphenylphosphine sulfide][O,O'-diethyl dithiophosphato]platinum. Inorg Chem 2002. [DOI: 10.1021/ic00284a032] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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24
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Ebner J. Counseling the pregnant worker. Nurs Spectr (Wash D C) 1997; 7:15. [PMID: 9431230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- J Ebner
- Public Health Service, New Carrollton, MD, USA
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25
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Abstract
A carpus valgus deformity was diagnosed in a five-week-old Brown Swiss calf. The 45 degrees deformity was caused by the malaligned healing of a fracture of the left metacarpus after birth trauma. The deviation improved to 25 degrees after being treated with a semicircular lateral periosteotomy above the distal physis of the radius. A complete correction was made by means of a wedge osteotomy five months after the first treatment. A 20 degrees wedge of bone was removed. The metacarpus was stabilised with a seven-hole dynamic compression plate which was removed 12 weeks later. Thirty months later the calf was sold as a pregnant heifer at an auction of breeding cattle.
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Affiliation(s)
- H Edinger
- Klinik für Orthopädie bei Huf- und Klauentieren, Veterinärmedizinische Universität Wien, Austria
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26
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Fernandez ML, Conde AK, Ruiz LR, Montano C, Ebner J, McNamara DJ. Carbohydrate type and amount alter intravascular processing and catabolism of plasma lipoproteins in guinea pigs. Lipids 1995; 30:619-26. [PMID: 7564916 DOI: 10.1007/bf02536998] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To test the effects of exchanging dietary complex and simple carbohydrate for fat calories on lipoprotein metabolism, guinea pigs were fed two different fat/carbohydrate ratios: 2.5:58% (w/w) or 25:29% (w/w) with either sucrose or starch as the carbohydrate source. Animals fed high-fat had higher plasma low-density lipoprotein (LDL) and hepatic cholesterol concentrations than animals fed low-fat diets (P < 0.01). The cholesteryl ester content per particle was higher, and the number of triacylglycerol (TAG) molecules was lower in very low density lipoprotein (VLDL) and LDL from animals fed high-fat diets. Intake of high-fat/sucrose resulted in higher plasma LDL concentrations than intake of high-fat/starch, and animals fed low-fat/starch had the highest plasma TAG concentrations associated with VLDL particles containing more TAG molecules, as well as a TAG-enriched LDL. The activity of plasma lecithin cholesteryl:acyl transferase (LCAT) was highest in animals fed high-fat/sucrose, and heart lipoprotein lipase (LPL) activity was higher in animals fed high-fat diets. Hepatic apoprotein B/E (apo B/E) receptor number (Bmax) was increased 21% with low-fat diets (P < 0.01). These results suggest that the hypercholesterolemia induced by high-fat and by sucrose intake are associated with a higher plasma LCAT activity which results in a cholesteryl ester-enriched VLDL which, by the action of LPL, might be more readily converted to LDL through the delipidation cascade leading to downregulation of hepatic apo B/E receptors. The hypertriglyceridemia associated with low-fat intake may result from increased production of VLDL TAG, which would explain the increased TAG content and the higher TAG/CE ratio of VLDL from animals fed the low-fat/starch diet.
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Affiliation(s)
- M L Fernandez
- Department of Nutritional Sciences, University of Arizona, Tucson 85721, USA
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27
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Kofler J, Ebner J. [Cauda equina syndrome in a Fleckvieh bull after a pathological fracture of the first sacral vertebra caused by a spindle cell sarcoma]. Tierarztl Prax 1993; 21:105-9. [PMID: 8488497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A 9 month old Simmental fattening bull was presented with signs of a cauda equina syndrome. An epidurographic examination was made after thorough clinical, neurological and routine radiographic examination. The cause of the cauda equina compression--a spindle cell sarcoma--was revealed by the pathologic-histologic examination. This tumor caused the compression of the cauda equina and pathologic transverse fracture of the body of the first sacral vertebra and cranial epiphyseal fracture of the 1st and the 3rd sacral vertebra as well as the separation of the arcus from the first and second sacral vertebral bodies. Some other diseases which can cause cauda equina syndrome are mentioned.
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Affiliation(s)
- J Kofler
- Klinik für Orthopädie bei Huf- und Klauentieren, Veterinärmedizinischen Universität Wien
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28
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Abstract
Glutamine is one major precursor of gamma-aminobutyric acid (GABA) and glutamate, the most important inhibitory and excitatory neurotransmitters in the mammalian brain, respectively. Changes in cerebral glutamine concentrations occur in various metabolic encephalopathies including hyperammonemia and liver failure. As glutamine inhibits the specific binding of GABA to its postsynaptic receptor at physiologic concentrations, in this study the effects of glutamine on various components of the GABAA-benzodiazepine receptor complex were studied. Glutamine dose dependently inhibited the stimulation of flunitrazepam binding by GABA. This inhibition occurred already at concentrations of 10 mumol/L glutamine. Glutamine had no effects on basal or GABA-stimulated synaptoneurosomal chloride uptake. It is concluded that glutamine is not a modulator of the GABAA-benzodiazepine neurotransmitter system. Thus, changes of cerebral glutamine concentrations are unlikely to contribute to the activation of GABA-ergic neurotransmission in liver failure.
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Affiliation(s)
- P Ferenci
- First Department of Gastroenterology and Hepatology, University of Vienna, Austria
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29
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Zimmermann C, Ferenci P, Pifl C, Yurdaydin C, Ebner J, Lassmann H, Roth E, Hörtnagl H. Hepatic encephalopathy in thioacetamide-induced acute liver failure in rats: characterization of an improved model and study of amino acid-ergic neurotransmission. Hepatology 1989; 9:594-601. [PMID: 2564368 DOI: 10.1002/hep.1840090414] [Citation(s) in RCA: 124] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
An imbalance of excitatory and inhibitory amino acid-ergic neurotransmission has been suggested to play a role in the pathogenesis of hepatic encephalopathy. For further evaluation of this hypothesis, several parameters of amino acid-ergic neurotransmission were studied in rats with acute liver failure induced by the administration of 300 mg per kg thioacetamide by gavage on two consecutive days. By appropriate supportive care, hypoglycemia, renal failure and hypothermia were avoided. Rats were monitored clinically and neurologically. Hepatic encephalopathy evolved in four distinct, easily recognizable stages. Light and electron microscopic examination of brains of rats with hepatic encephalopathy revealed only a slight swelling of nuclei of neurons and astrocytes without signs of neuronal degeneration or brain edema. In rats with hepatic encephalopathy, the concentrations of GABA, glutamate and taurine were decreased in the cerebral cortex, the hippocampus and the striatum, whereas those of aspartate and glycine were unchanged or increased. GABAA and benzodiazepine receptors were studied as parameters for the postsynaptic GABAA-benzodiazepine receptor complex, glutamic acid decarboxylase as parameter for presynaptic GABA-ergic neurons and stimulation of benzodiazepine binding by GABA as a parameter for a GABA-mediated postsynaptic event. None of these parameters was different in hepatic encephalopathy as compared to controls. Similarly, Ca++/Cl(-)-dependent and -independent glutamate receptors as parameters for glutamatergic neurons were unchanged in rats with hepatic encephalopathy. Thus, in rats with thioacetamide-induced liver failure and hepatic encephalopathy, changes of the concentrations of neurotransmitter amino acids occur in the brain. Other neurochemical parameters, however, failed to identify alterations of GABA-ergic or glutamatergic neurotransmission in hepatic encephalopathy.
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Affiliation(s)
- C Zimmermann
- Department of Gastroenterology and Hepatology, University of Vienna, Austria
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30
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Abstract
Serum concentrations of gamma-aminobutyric acid (GABA) are increased in liver failure, possibly because of decreased hepatic GABA catabolism. To study in detail the role of the liver in GABA metabolism, uptake and catabolism of GABA by isolated perfused liver from normal rats and rats with galactosamine- or carbon tetrachloride-induced liver failure were measured. Hepatic GABA uptake was almost complete at GABA concentrations of up to 10 microM and approached saturation at a concentration of 50 microM. The apparent affinity of hepatic GABA uptake was 38 microM and the apparent maximal velocity was 158 nmol/g.min. Hepatic GABA uptake was sodium-dependent. gamma-Aminobutyric acid taken up by the liver was rapidly catabolized as measured by 14CO2 formation from [U-14C]GABA. Aminooxyacetic acid, a GABA transaminase inhibitor, completely and irreversibly inhibited hepatic GABA catabolism and thereby also inhibited hepatic GABA uptake. Although uptake of GABA by livers of carbon tetrachloride- or galactosamine-treated rats was decreased (apparent maximal velocity, 103 and 98 nmol/g.min, respectively), at physiologic GABA concentrations in the perfusate GABA uptake and catabolism was not different from that of untreated controls. The observed impairment of hepatic GABA uptake or catabolism by the diseased liver would be expected to contribute to increased GABA levels in peripheral blood plasma in liver failure. However, the magnitude of the observed impairment would be insufficient to account for a 10-fold increase in such levels.
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Affiliation(s)
- P Ferenci
- First Department of Gastroenterology and Hepatology, University of Vienna, Austria
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31
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Ferenci P, Ebner J, Zimmermann C, Kikuta C, Roth E, Häussinger D. Overestimation of serum concentrations of gamma-aminobutyric acid in patients with hepatic encephalopathy by the gamma-aminobutyric acid-radioreceptor assay. Hepatology 1988; 8:69-72. [PMID: 2828213 DOI: 10.1002/hep.1840080114] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Sera of patients with hepatic encephalopathy strongly inhibit the specific binding of gamma-aminobutyric acid to synaptic membranes. In a previous study, this inhibition of specific gamma-aminobutyric acid binding was attributed to gamma-aminobutyric acid itself, and it was assumed that serum gamma-aminobutyric acid is increased 5- to 30-fold in patients with hepatic encephalopathy. The findings of that study, however, were not confirmed by other analytical methods. Therefore, the validity of the gamma-aminobutyric acid-radioreceptor assay was tested. In view of the increased serum concentrations of several amino acids in hepatic encephalopathy, the effects of L-alpha-amino acids on the assay were studied. Five amino acids inhibited specific gamma-aminobutyric acid binding at a concentration of 0.5 mM or lower: glutamine; glutamate; taurine; proline, and OH-proline. Equimolar amounts of aminooxyacetate prevented the inhibition of specific gamma-aminobutyric acid binding by glutamine and glutamate but had no effect on that of gamma-aminobutyric acid, taurine, proline and OH-proline. Aminooxyacetate had no effect on specific gamma-aminobutyric acid binding itself. The inhibitory activity of a serum sample from a patient with hepatic encephalopathy was inhibited by 0.5 mM aminooxyacetate. The gamma-aminobutyric acid binding inhibitory activity of a serum sample of a patient with hepatic encephalopathy was purified by gel chromatography and contained several amino acids at concentrations of about 0.1 mM, 3.5 mM glutamine but no detectable gamma-aminobutyric acid. Accordingly, the gamma-aminobutyric acid binding inhibitory activity is not mediated by gamma-aminobutyric acid alone and is most likely due to glutamine.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P Ferenci
- Department of Gastroenterology and Hepatology, University of Vienna, Austria
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32
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Zieve L, Ferenci P, Rzepczynski D, Ebner J, Zimmermann C. A benzodiazepine antagonist does not alter the course of hepatic encephalopathy or neural gamma-aminobutyric acid (GABA) binding. Metab Brain Dis 1987; 2:201-5. [PMID: 2850457 DOI: 10.1007/bf00999611] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The progressive course of hepatic encephalopathy developing in rats after massive hepatic ischemia due to hepatic artery ligation within 48 hr of a portacaval shunt was not altered by the injection of a benzodiazepine antagonist, CGS 8216, in a dose that was sufficient to reverse diazepam-induced coma quickly. The onset of hepatic coma was shortened 20 to 25% by the antagonist, rather than being delayed, as would be expected if hepatic coma were due to a gamma-aminobutyric acid (GABA)-ergic effect. The neural binding of GABA by brains from rats in deep hepatic coma was unaffected by the injection of the benzodiazepine antagonist.
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Affiliation(s)
- L Zieve
- VA Medical Center, Minneapolis, Minnesota
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33
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Ferenci P, Zieve L, Ebner J, Zimmermann C, Rzepczynski D. Postsynaptic gamma-aminobutyric acid receptors in hepatic coma following portacaval shunt and hepatic artery ligation in the rat. Metab Brain Dis 1987; 2:195-200. [PMID: 2850456 DOI: 10.1007/bf00999610] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The specific binding of gamma-aminobutyric acid (GABA) to synaptic membranes prepared from the brains of rats with acute liver failure due to portacaval shunt and hepatic artery ligation was measured. No changes in the affinity or the density of the low- and high-affinity binding sites of the GABA receptor were observed, indicating that this model of acute hepatic encephalopathy is apparently not associated with altered GABAergic neurotransmission.
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Affiliation(s)
- P Ferenci
- Department of Gastroenterology and Hepatology, University of Vienna Medical School, Austria
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