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Binsch C, Barbosa DM, Hansen-Dille G, Hubert M, Hodge SM, Kolasa M, Jeruschke K, Weiß J, Springer C, Gorressen S, Fischer JW, Lienhard M, Herwig R, Börno S, Timmermann B, Cremer AL, Backes H, Chadt A, Al-Hasani H. Deletion of Tbc1d4/As160 abrogates cardiac glucose uptake and increases myocardial damage after ischemia/reperfusion. Cardiovasc Diabetol 2023; 22:17. [PMID: 36707786 PMCID: PMC9881301 DOI: 10.1186/s12933-023-01746-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/17/2023] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Type 2 Diabetes mellitus (T2DM) is a major risk factor for cardiovascular disease and associated with poor outcome after myocardial infarction (MI). In T2DM, cardiac metabolic flexibility, i.e. the switch between carbohydrates and lipids as energy source, is disturbed. The RabGTPase-activating protein TBC1D4 represents a crucial regulator of insulin-stimulated glucose uptake in skeletal muscle by controlling glucose transporter GLUT4 translocation. A human loss-of-function mutation in TBC1D4 is associated with impaired glycemic control and elevated T2DM risk. The study's aim was to investigate TBC1D4 function in cardiac substrate metabolism and adaptation to MI. METHODS Cardiac glucose metabolism of male Tbc1d4-deficient (D4KO) and wild type (WT) mice was characterized using in vivo [18F]-FDG PET imaging after glucose injection and ex vivo basal/insulin-stimulated [3H]-2-deoxyglucose uptake in left ventricular (LV) papillary muscle. Mice were subjected to cardiac ischemia/reperfusion (I/R). Heart structure and function were analyzed until 3 weeks post-MI using echocardiography, morphometric and ultrastructural analysis of heart sections, complemented by whole heart transcriptome and protein measurements. RESULTS Tbc1d4-knockout abolished insulin-stimulated glucose uptake in ex vivo LV papillary muscle and in vivo cardiac glucose uptake after glucose injection, accompanied by a marked reduction of GLUT4. Basal cardiac glucose uptake and GLUT1 abundance were not changed compared to WT controls. D4KO mice showed mild impairments in glycemia but normal cardiac function. However, after I/R D4KO mice showed progressively increased LV endsystolic volume and substantially increased infarction area compared to WT controls. Cardiac transcriptome analysis revealed upregulation of the unfolded protein response via ATF4/eIF2α in D4KO mice at baseline. Transmission electron microscopy revealed largely increased extracellular matrix (ECM) area, in line with decreased cardiac expression of matrix metalloproteinases of D4KO mice. CONCLUSIONS TBC1D4 is essential for insulin-stimulated cardiac glucose uptake and metabolic flexibility. Tbc1d4-deficiency results in elevated cardiac endoplasmic reticulum (ER)-stress response, increased deposition of ECM and aggravated cardiac damage following MI. Hence, impaired TBC1D4 signaling contributes to poor outcome after MI.
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Affiliation(s)
- C. Binsch
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - D. M. Barbosa
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - G. Hansen-Dille
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - M. Hubert
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - S. M. Hodge
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - M. Kolasa
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - K. Jeruschke
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - J. Weiß
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - C. Springer
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany
| | - S. Gorressen
- grid.411327.20000 0001 2176 9917Institute for Pharmacology and Clinical Pharmacology, Heinrich-Heine-University, Düsseldorf, Germany
| | - J. W. Fischer
- grid.411327.20000 0001 2176 9917Institute for Pharmacology and Clinical Pharmacology, Heinrich-Heine-University, Düsseldorf, Germany
| | - M. Lienhard
- grid.419538.20000 0000 9071 0620Max-Planck-Institute for Molecular Genetics, Berlin, Germany
| | - R. Herwig
- grid.419538.20000 0000 9071 0620Max-Planck-Institute for Molecular Genetics, Berlin, Germany
| | - S. Börno
- grid.419538.20000 0000 9071 0620Max-Planck-Institute for Molecular Genetics, Berlin, Germany
| | - B. Timmermann
- grid.419538.20000 0000 9071 0620Max-Planck-Institute for Molecular Genetics, Berlin, Germany
| | - A. L. Cremer
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Cologne, Germany
| | - H. Backes
- grid.418034.a0000 0004 4911 0702Max Planck Institute for Metabolism Research, Cologne, Germany
| | - A. Chadt
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany ,grid.452622.5German Center for Diabetes Research, Partner Düsseldorf, Munich-Neuherberg, Germany
| | - H. Al-Hasani
- grid.429051.b0000 0004 0492 602XMedical Faculty, Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Leibniz-Center for Diabetes Research at Heinrich Heine University Düsseldorf, Auf’m Hennekamp 65, 40225 Düsseldorf, Germany ,grid.452622.5German Center for Diabetes Research, Partner Düsseldorf, Munich-Neuherberg, Germany
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Blaschke S, Vlachakis S, Olschewski D, Ladwig A, Anna-Lena C, Backes H, Aswendt M, Fink G, Schroeter M, Rueger M. FV 13 Transcranial direct current stimulation modulates stroke-induced secondary thalamic neurodegeneration in mice. Clin Neurophysiol 2022. [DOI: 10.1016/j.clinph.2022.01.021] [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: 11/03/2022]
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Backes H, Ruffing S. Ein seltener, gastrointestinaler Notfall. Radiologe 2018; 58:355-358. [DOI: 10.1007/s00117-017-0343-7] [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: 11/24/2022]
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Abstract
The increasing migration of people from their homeland in far distant regions to Europe in the last few years has strongly influenced the rise of previously rarely seen diseases. They not only originate from the respective homeland but also from the transit countries during the migration process. We report the case of a 27-year-old male migrant from Eritrea, who after months of flight as a refugee travelling through various African countries, presented at our hospital with a progressive, painful radiculopathy. Whole spine magnetic resonance imaging (MRI) showed a focus located in the myelon, extending from T11 to the medullary conus. The differential diagnostic clarification ultimately revealed an infection with Schistosoma mansoni. After guideline-conform treatment with praziquantel for 3 days and additional administration of corticosteroids for 3 months, a slow regression of the findings and improvement of the symptoms could be shown clinically and by MRI. This case study shows the importance of taking the medical history and that a closer look at the potential exposure in the homeland and transit countries should be of great benefit in reaching the diagnosis, especially in patients with a migration background.
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Affiliation(s)
- J Detzler
- Neurologische Abteilung, Knappschaftsklinikum Saar GmbH, Standort Püttlingen, In der Humes 35, 66346, Püttlingen, Deutschland.
| | - H Backes
- Radiologische Abteilung, Knappschaftsklinikum Saar GmbH, Standort Püttlingen, Püttlingen, Deutschland
| | - J Guldner
- Neurologische Abteilung, Knappschaftsklinikum Saar GmbH, Standort Püttlingen, In der Humes 35, 66346, Püttlingen, Deutschland
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Paulissen J, Offermann C, Houben R, Van Erp E, Brouns M, Backes H, Boersma L, Vreuls G, Lemmen R, Dekker A, Lambin P, Jacobs M, Smits K. PO-0783: Implementation of a trial outpatient clinic to improve participation and data collection in trials. Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)32033-3] [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: 10/21/2022]
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Simons P, Houben R, Backes H, Reijnders P, Jacobs M. SP-0601: Does lean management improve patient safety culture? Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)31851-5] [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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7
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Gramer M, Feuerstein D, Steimers A, Takagaki M, Kumagai T, Sué M, Vollmar S, Kohl-Bareis M, Backes H, Graf R. Device for simultaneous positron emission tomography, laser speckle imaging and RGB reflectometry: validation and application to cortical spreading depression and brain ischemia in rats. Neuroimage 2014; 94:250-262. [PMID: 24657778 DOI: 10.1016/j.neuroimage.2014.03.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [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: 10/08/2013] [Revised: 02/06/2014] [Accepted: 03/10/2014] [Indexed: 11/16/2022] Open
Abstract
Brain function critically relies on the supply with energy substrates (oxygen and glucose) via blood flow. Alterations in energy demand as during neuronal activation induce dynamic changes in substrate fluxes and blood flow. To study the complex system that regulates cerebral metabolism requires the combination of methods for the simultaneous assessment of multiple parameters. We developed a multimodal imaging device to combine positron emission tomography (PET) with laser speckle imaging (LSI) and RGB reflectometry (RGBR). Depending on the radiotracer, PET provides 3-dimensional quantitative information of specific molecular processes, while LSI and RGBR measure cerebral blood flow (CBF) and hemoglobin oxygenation at high temporal and spatial resolution. We first tested the functional capability of each modality within our system and showed that interference between the modalities is negligible. We then cross-calibrated the system by simultaneously measuring absolute CBF using (15)O-H2O PET (CBF(PET)) and the inverse correlation time (ICT), the LSI surrogate for CBF. ICT and CBF(PET) correlated in multiple measurements in individuals as well as across different animals (R(2)=0.87, n=44 measurements) indicating that ICT can be used for absolute quantitative assessment of CBF. To demonstrate the potential of the combined system, we applied it to cortical spreading depression (CSD), a wave of transient cellular depolarization that served here as a model system for neurovascular and neurometabolic coupling. We analyzed time courses of hemoglobin oxygenation and CBF alterations coupled to CSD, and simultaneously measured regional uptake of (18)F-2-fluoro-2-deoxy-D-glucose ((18)F-FDG) used as a radiotracer for regional glucose metabolism, in response to a single CSD and to a cluster of CSD waves. With this unique combination, we characterized the changes in cerebral metabolic rate of oxygen (CMRO2) in real-time and showed a correlation between (18)F-FDG uptake and the number of CSD waves that passed the local tissue. Finally, we examined CSD spontaneously occurring during focal ischemia also referred to as peri-infarct depolarization (PID). In the vicinity of the ischemic territory, we observed PIDs that were characterized by reduced CMRO2 and increased oxygen extraction fraction (OEF), indicating a limitation of oxygen supply. Simultaneously measured PET showed an increased (18)F-FDG uptake in these regions. Our combined system proved to be a novel tool for the simultaneous study of dynamic spatiotemporal alterations of cortical blood flow, oxygen metabolism and glucose consumption under normal and pathologic conditions.
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Affiliation(s)
- M Gramer
- Max-Planck-Institute of Neurological Research, Gleueler Str. 50, 50825 Cologne, Germany.
| | - D Feuerstein
- Max-Planck-Institute of Neurological Research, Gleueler Str. 50, 50825 Cologne, Germany
| | - A Steimers
- RheinAhrCampus Remagen, University of Applied Sciences Koblenz, Joseph-Rovan Allee 2, 53424 Remagen, Germany
| | - M Takagaki
- Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - T Kumagai
- Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - M Sué
- Max-Planck-Institute of Neurological Research, Gleueler Str. 50, 50825 Cologne, Germany
| | - S Vollmar
- Max-Planck-Institute of Neurological Research, Gleueler Str. 50, 50825 Cologne, Germany
| | - M Kohl-Bareis
- RheinAhrCampus Remagen, University of Applied Sciences Koblenz, Joseph-Rovan Allee 2, 53424 Remagen, Germany
| | - H Backes
- Max-Planck-Institute of Neurological Research, Gleueler Str. 50, 50825 Cologne, Germany
| | - R Graf
- Max-Planck-Institute of Neurological Research, Gleueler Str. 50, 50825 Cologne, Germany
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Soman R, Dekker A, Emans D, Jacobs M, Backes H, Van Merode F. EP-1425: Prediction of waiting time for lung cancer patients. Radiother Oncol 2014. [DOI: 10.1016/s0167-8140(15)31543-7] [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: 10/23/2022]
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9
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Schroeter M, Walberer M, Jantzen S, Backes H, Rueger M, Neumaier B, Endepols H, Hoehn M, Graf R, Fink G. In-Vivo Detection of Late Persistent Microglia Activation in the Chronic Phase of Embolic Stoke in Rats (PD2.002). Neurology 2012. [DOI: 10.1212/wnl.78.1_meetingabstracts.pd2.002] [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: 11/15/2022] Open
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10
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Rueger MA, Muesken S, Walberer M, Jantzen SU, Schnakenburg K, Backes H, Graf R, Neumaier B, Hoehn M, Fink GR, Schroeter M. Effects of minocycline on endogenous neural stem cells after experimental stroke. Neuroscience 2012; 215:174-83. [PMID: 22542871 DOI: 10.1016/j.neuroscience.2012.04.036] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 04/13/2012] [Indexed: 01/09/2023]
Abstract
Minocycline has been reported to reduce infarct size after focal cerebral ischemia, due to an attenuation of microglia activation and prevention of secondary damage from stroke-induced neuroinflammation. We here investigated the effects of minocycline on endogenous neural stem cells (NSCs) in vitro and in a rat stroke model. Primary cultures of fetal rat NSCs were exposed to minocycline to characterize its effects on cell survival and proliferation. To assess these effects in vivo, permanent cerebral ischemia was induced in adult rats, treated systemically with minocycline or placebo. Imaging 7 days after ischemia comprised (i) Magnetic Resonance Imaging (MRI), assessing the extent of infarcts, (ii) Positron Emission Tomography (PET) with [(11)C]PK11195, characterizing neuroinflammation, and (iii) PET with 3'-deoxy-3'-[(18)F]fluoro-L-thymidine ([(18)F]FLT), detecting proliferating endogenous NSCs. Immunohistochemistry was used to verify ischemic damage and characterize cellular inflammatory and repair processes in more detail. In vitro, specific concentrations of minocycline significantly increased NSC numbers without increasing their proliferation, indicating a positive effect of minocycline on NSC survival. In vivo, endogenous NSC activation in the subventricular zone (SVZ) measured by [(18)F]FLT PET correlated well with infarct volumes. Similar to in vitro findings, minocycline led to a specific increase in endogenous NSC activity in both the SVZ as well as the hippocampus. [(11)C]PK11195 PET detected neuroinflammation in the infarct core as well as in peri-infarct regions, with both its extent and location independent of the infarct size. The data did not reveal an effect of minocycline on stroke-induced neuroinflammation. We show that multimodal PET imaging can be used to characterize and quantify complex cellular processes occurring after stroke, as well as their modulation by therapeutic agents. We found minocycline, previously implied in attenuating microglial activation, to have positive effects on endogenous NSC survival. These findings hold promise for the development of novel treatments in stroke therapy.
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Affiliation(s)
- M A Rueger
- Department of Neurology, University Hospital of Cologne, Germany.
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Rueger MA, Backes H, Walberer M, Neumaier B, Ullrich R, Emig B, Simard ML, Fink GR, Hoehn M, Graf R, Schroeter M. Non-invasive imaging of endogenous neural stem cell mobilization in vivo using Positron Emission Tomography. KLIN NEUROPHYSIOL 2012. [DOI: 10.1055/s-0032-1301486] [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: 10/28/2022]
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12
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Nogova L, Mattonet C, Scheffler M, Papachristou I, Muthen N, Sos M, Hacker UT, Elter T, Backes H, Kobe C, Rhiem K, Mallmann P, Fuhr U, Schnell R, Katay I, Toepelt K, Reiser M, Harbeck N, Dietlein M, Wolf J. The combination of sorafenib and everolimus in patients with solid tumors: Results of a phase I study. J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.15_suppl.e13613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Monfared P, Viel T, Schneider G, Waerzeggers Y, Rapic S, Neumaier B, Backes H, Winkeler A, Jacobs A. Targeting the p53 tumor suppressor activity in glioblastomas using small molecule MDM2-inhibitor. KLIN NEUROPHYSIOL 2011. [DOI: 10.1055/s-0031-1272660] [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: 10/18/2022]
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Rapic S, Backes H, Viel T, Monfared P, Neumaier B, Vollmar S, Hoehn M, Van der Linden A, Heneka M, Jacobs A. Multi-tracer microPET imaging of a mouse model of Alzheimer's disease to assess microglial activation and anti-inflammatory treatment. KLIN NEUROPHYSIOL 2011. [DOI: 10.1055/s-0031-1272776] [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: 10/18/2022]
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Ullrich R, Backes H, Li H, Kracht L, Miletic H, Kesper K, Neumaier B, Heiss W, Wienhard K, Jacobs A. Glioma proliferation as assessed by FLT-PET in patients with newly diagnosed high grade glioma. Akt Neurol 2008. [DOI: 10.1055/s-0028-1086545] [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: 10/21/2022]
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Abstract
Drooling is a common and severe problem in children with neurological disorders and is caused by a disturbed coordination of orofacial and palatolingual muscles. Botulinum toxin could be a successful option to reduce excessive sialorrhea in children with neurological disorders. In 30 children with cerebral palsy or neurodegenerative disorder we injected under ultrasound guidance either botulinum toxin A or botulinum toxin B into the parotid and submandibular glands on both sides. All injections were well tolerated without general anaesthesia. Drooling severity at baseline and reduction of sialorrhea during treatment was measured using a parent's questionnaire and rated using the Teachers Drooling Scale (TDS). Reduction of sialorrhea was achieved two weeks after injection, with a positive effect lasting about three to four months in most children. 83% showed a good response to botulinum toxin after first injection, but only in 50% treatment was continued. We found no significant differences between botulinum toxin A or B. Side effects were observed in 5 children with viscous saliva and in one child a unilateral parotitis was observed. Treatment of drooling with botulinum toxin into the salivary glands is a safe and easy therapeutic option for children with neurological disorders to improve life quality.
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Affiliation(s)
- B Wilken
- Department of Pediatric Neurology, Klinikum Kassel, Kassel, Germany.
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Ullrich R, Kracht L, Backes H, Kesper K, Wienhard K, Jacobs A. 3'-Deoxy-3'-18F-Fluoro-L-thymidine positron emission tomography for the non-invasive assessment of proliferation in gliomas. KLIN NEUROPHYSIOL 2007. [DOI: 10.1055/s-2007-976434] [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: 10/21/2022]
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Neubauer FM, Backes H, Dougherty MK, Wennmacher A, Russell CT, Coates A, Young D, Achilleos N, André N, Arridge CS, Bertucci C, Jones GH, Khurana KK, Knetter T, Law A, Lewis GR, Saur J. Titan's near magnetotail from magnetic field and electron plasma observations and modeling: Cassini flybys TA, TB, and T3. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2006ja011676] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kraiczy P, Weigand J, Wichelhaus TA, Heisig P, Backes H, Schäfer V, Acker G, Brade V, Hunfeld KP. In vitro activities of fluoroquinolones against the spirochete Borrelia burgdorferi. Antimicrob Agents Chemother 2001; 45:2486-94. [PMID: 11502519 PMCID: PMC90682 DOI: 10.1128/aac.45.9.2486-2494.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [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: 11/20/2022] Open
Abstract
Little is known to date about the in vitro activity of fluoroquinolones against Borrelia species. Our study aimed at determining the in vitro activities of 15 quinolones against nine isolates of the Borrelia burgdorferi sensu lato complex in addition to one Borrelia valaisiana and one Borrelia bissettii tick isolate. For the determination of MICs, a standardized colorimetric microdilution method was applied. Determination of minimal borreliacidal concentrations providing 100% killing of the final inoculum (MBCs) after 72 h and time-kill experiments were performed by conventional culture in Barbour-Stoenner-Kelly medium in combination with dark-field microscopy. The rank order of potency on a microgram-per-milliliter basis for the substances with in vitro activity against B. burgdorferi was gemifloxacin (MIC at which 90% of the isolates tested are inhibited [MIC(90)], 0.12 microg/ml) > sitafloxacin (MIC(90), 0.5 microg/ml), grepafloxacin (MIC(90), 0.5 microg/ml) > gatifloxacin (MIC(90), 1 microg/ml), sparfloxacin (MIC(90), 1 microg/ml), trovafloxacin (MIC(90), 1 microg/ml) > moxifloxacin (MIC(90), 2 microg/ml), ciprofloxacin (MIC(90), 2 microg/ml) > levofloxacin (MIC(90), 4 microg/ml) > ofloxacin (MIC(90), 8 microg/ml), norfloxacin (MIC(90), 8 microg/ml) > fleroxacin (MIC(90), >16 microg/ml), and pefloxacin (MIC(90), 32 microg/ml) > nalidixic acid (MIC(90), 256 microg/ml). After 72 h of exposure, gemifloxacin was borreliacidal (100% killing) against the isolates investigated at a median MBC of 4 microg/ml. In the other compounds tested, median MBCs were higher (> or =8 microg/ml). Results of electron microscopy and time-kill studies clearly support an in vitro activity of some fluoroquinolones against borreliae. Our study demonstrates for the first time the enhanced in vitro effectiveness of some of the recently introduced 4-quinolones against B. burgdorferi.
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Affiliation(s)
- P Kraiczy
- Institute of Medical Microbiology, University Hospital of Frankfurt, D-60596 Frankfurt/Main, Germany
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Neubauer H, Molitor M, Rahalison L, Aleksic S, Backes H, Chanteau S, Meyer H. A miniaturised semiautomated system for the identification of Yersinia species within the genus Yersinia. Clin Lab 2001; 46:561-7. [PMID: 11109503] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Commercially available identification systems based on biochemical reactions of bacteria are not suited for typing the species of the genus Yersinia (Y.) or the biovars (BV) of the species Y. enterocolitica. This failure is caused by the limited number of biochemical reactions applied, resulting in the absence of important discriminatory key reactions. The MICRONAUT identification system (Merlin, Bornheim-Hersel) makes use of dried substrates/enzymes reactions in the wells of a 96-well microtitration plate, reading of the results by a scanner device and typing of the isolate by the calculation of probabilities according to a data base. For this study a special identification panel was designed on which 38 substrates and enzyme reactions were configurated including 20 reactions for the identification of the species of the genus and the Y. enterocolitica biovars. The database was calculated using the results obtained from a total of 250 Yersinia strains of the eleven species of the genus. Reevaluation of the results of these strains revealed an overall sensitivity of 98%, as only four strains were not identified satisfactorily. Considering also questionable results the sensitivity was still 85%. The system was also used to identify Y. pestis isolates, but in this case reading was done visually. The printouts usually cite species designation, identification quality and probabilities. The sealing of the plates in an aluminium bag guarantees long life and long lasting quality. However, an evaluation of the system with a considerable number of strains has to be done in a next step. The 'Yersinia identification set' can replace time-consuming tube testing in the future and is a big step forward towards a sensitive identification of Yersinia isolates in the routine laboratory.
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Affiliation(s)
- H Neubauer
- Institute of Microbiology, German Armed Forces Medical Academy, Munich, Germany.
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Backes H, Berens C, Helbl V, Walter S, Schmid FX, Hillen W. Combinations of the alpha-helix-turn-alpha-helix motif of TetR with respective residues from LacI or 434Cro: DNA recognition, inducer binding, and urea-dependent denaturation. Biochemistry 1997; 36:5311-22. [PMID: 9154913 DOI: 10.1021/bi961527k] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [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: 02/04/2023]
Abstract
We constructed 10 different variants of TetR by substituting all or some of the residues in the alpha-helix-turn-alpha-helix (HTH) operator binding motif with the respective amino acids from LacI or 434Cro. The variants were soluble, negative transdominant over tetR in vivo, and as active as wild-type TetR in tetracycline binding in vitro. The urea-induced denaturation of the 10 variants occurs in single reversible transitions, which are centered around 4.3 M urea. Denaturation is concentration-dependent, supporting a simple two-state mechanism in which the folded dimeric protein is in equilibrium with unfolded monomers. An analysis according to the two-state model yields a Gibbs free energy of stabilization (at 0 M urea, 25 degrees C) of about 75 kJ/mol, typical for dimeric proteins of this size. Even a deletion of 24 residues from the reading head decreased the stability by only 2.7 kJ/mol. These results suggest that the DNA reading head of Tet repressor is a thermodynamically independent domain and that the thermodynamic stability of the Tet repressor dimer is determined by the association of the dimerization domains of the individual monomers. Variants containing replacements in the first alpha-helix of HTH did not show any DNA binding activity whatsoever. We attribute this to the alteration of the two N-terminal residues in this alpha-helix. TetR variants were active in nonspecific DNA binding, when either all or only the solvent-exposed residues in the recognition alpha-helix of HTH were exchanged to the respective LacI sequence. Replacement of the same residues by the respective amino acids from 434Cro yielded hybrid proteins that specifically recognize tetO in vitro. Taken together, these results establish that the similarity of operator recognition between 434Cro and TetR is greater than between TetR and LacI and confirm that prediction of the recognized DNA sequence is not obvious from the sequence of the respective HTH or recognition alpha-helix.
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Affiliation(s)
- H Backes
- Lehrstuhl für Mikrobiologie, Biochemie und Genetik der Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Ettner N, Müller G, Berens C, Backes H, Schnappinger D, Schreppel T, Pfleiderer K, Hillen W. Fast large-scale purification of tetracycline repressor variants from overproducing Escherichia coli strains. J Chromatogr A 1996; 742:95-105. [PMID: 8817886 DOI: 10.1016/0021-9673(96)00232-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [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: 02/02/2023]
Abstract
We constructed a plasmid for overexpression of Tn10 Tet repressor (TetR) by placing a synthetic tetR gene under control of the Pc promoter. Active TetR is expressed up to 30% of the total soluble cell protein. A protocol containing anion-exchange, cation-exchange, and size-exclusion chromatography steps is described for the large-scale purification of milligram amounts of TetR in three days. Cation-exchange chromatography already yields almost homogenous TetR. Purification of about fifty TetR mutants demonstrates that this protocol is generally applicable. No correlation between net charge of TetR variants and elution behaviour was detected for the anion-exchange column. On the other hand, TetR mutants with increased negative charge in their DNA binding domain eluted at lower NaCl concentration from the cation-exchange column. The applicability of this purification protocol to the wide variety of TetR variants suggests that it can be used for the rapid purification of other DNA binding proteins as well.
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Affiliation(s)
- N Ettner
- Lehrstuhl für Mikrobiologie, Institut für Mikrobiologie und Biochemie, Friedrich Alexander Universität Erlangen-Nürnberg, Germany
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Henrich B, Backes H, Klein JR, Plapp R. The promoter region of the Escherichia coli pepD gene: deletion analysis and control by phosphate concentration. Mol Gen Genet 1992; 232:117-25. [PMID: 1313142 DOI: 10.1007/bf00299144] [Citation(s) in RCA: 8] [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] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A series of deletions removing progressively larger parts of the 5' flanking region of the Escherichia coli pepD gene was constructed. After fusing the resulting promoter fragments to the chromosomal malPQ operon, their activities were determined by assaying for amylomaltase, the product of the malQ gene. Transcription from the pepD promoter region in exponentially growing cells was estimated to be about 5 times less efficient than transcription from the induced lac promoter. Approximately 115 bp preceding the translation start site of the pepD gene are important for regular promoter functioning, whereas the more distal sequences could be deleted without any significant effects. In bacterial cultures containing limiting amounts of inorganic phosphate, the rate of de novo synthesis of peptidase D, simultaneously with the derepression of alkaline phosphatase, increased about fivefold as a consequence of phosphate starvation. This regulation was shown to occur at the transcriptional level by the use of chromosomal pepD promoter-malPQ fusions. The inducibility by phosphate limitation was conserved in all of the deletion clones in which the pepD promoter region was still functional. As demonstrated by the use of phoB, R, and M mutants, the modulation of pepD expression is independent of the genetic system controlling the pho regulon.
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Affiliation(s)
- B Henrich
- Universität Kaiserslautern, Fachbereich Biologie, FRG
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Robert P, Backes H. Untersuchungen über das cholesterolytische Vermögen des Blutserums, insbesondere bei Psoriasis. Dermatology 1942. [DOI: 10.1159/000254964] [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: 11/19/2022] Open
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