1,650 results on '"A M Hermann"'
Search Results
52. Lithium modulates miR‐1906 levels of mesenchymal stem cell‐derived extracellular vesicles contributing to poststroke neuroprotection by toll‐like receptor 4 regulation
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Matteo Haupt, Xuan Zheng, Yaoyun Kuang, Simone Lieschke, Lisa Janssen, Bert Bosche, Fengyan Jin, Katharina Hein, Ertugrul Kilic, Vivek Venkataramani, Dirk M. Hermann, Mathias Bähr, and Thorsten R. Doeppner
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cerebral ischemia ,extracellular vesicles ,lithium ,mesenchymal stem cells ,miR‐1906 ,TLR4 ,Medicine (General) ,R5-920 ,Cytology ,QH573-671 - Abstract
Abstract Lithium is neuroprotective in preclinical stroke models. In addition to that, poststroke neuroregeneration is stimulated upon transplantation of mesenchymal stem cells (MSCs). Preconditioning of MSCs with lithium further enhances the neuroregenerative potential of MSCs, which act by secreting extracellular vesicles (EVs). The present work analyzed whether MSC preconditioning with lithium modifies EV secretion patterns, enhancing the therapeutic potential of such derived EVs (Li‐EVs) in comparison with EVs enriched from native MSCs. Indeed, Li‐EVs significantly enhanced the resistance of cultured astrocytes, microglia, and neurons against hypoxic injury when compared with controls and to native EV‐treated cells. Using a stroke mouse model, intravenous delivery of Li‐EVs increased neurological recovery and neuroregeneration for as long as 3 months in comparison with controls and EV‐treated mice, albeit the latter also showed significantly better behavioral test performance compared with controls. Preconditioning of MSCs with lithium also changed the secretion patterns for such EVs, modifying the contents of various miRNAs within these vesicles. As such, Li‐EVs displayed significantly increased levels of miR‐1906, which has been shown to be a new regulator of toll‐like receptor 4 (TLR4) signaling. Li‐EVs reduced posthypoxic and postischemic TLR4 abundance, resulting in an inhibition of the nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) signaling pathway, decreased proteasomal activity, and declined both inducible NO synthase and cyclooxygenase‐2 expression, all of which culminated in reduced levels of poststroke cerebral inflammation. Conclusively, the present study demonstrates, for the first time, an enhanced therapeutic potential of Li‐EVs compared with native EVs, interfering with a novel signaling pathway that yields both acute neuroprotection and enhanced neurological recovery.
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- 2021
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53. Induced Coma, Death, and Organ Transplantation: A Physiologic, Genetic, and Theological Perspective
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Cezar-Ivan Coliță, Denissa-Greta Olaru, Daniela Coliță, Dirk M. Hermann, Eugen Coliță, Daniela Glavan, and Aurel Popa-Wagner
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death ,genetics ,cellular proliferation ,apoptosis ,proteasomal degradation ,cancer ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
In the clinic, the death certificate is issued if brain electrical activity is no longer detectable. However, recent research has shown that in model organisms and humans, gene activity continues for at least 96 h postmortem. The discovery that many genes are still working up to 48 h after death questions our definition of death and has implications for organ transplants and forensics. If genes can be active up to 48 h after death, is the person technically still alive at that point? We discovered a very interesting parallel between genes that were upregulated in the brain after death and genes upregulated in the brains that were subjected to medically-induced coma, including transcripts involved in neurotransmission, proteasomal degradation, apoptosis, inflammation, and most interestingly, cancer. Since these genes are involved in cellular proliferation, their activation after death could represent the cellular reaction to escape mortality and raises the question of organ viability and genetics used for transplantation after death. One factor limiting the organ availability for transplantation is religious belief. However, more recently, organ donation for the benefit of humans in need has been seen as “posthumous giving of organs and tissues can be a manifestation of love spreading also to the other side of death”.
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- 2023
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54. N-Methyl-D-Aspartate Receptors Antagonist Prevents Secondary Ischemic Brain Injury Associated With Lipopolysaccharide-Induced Sepsis-Like State Presumably via Immunomodulatory Actions
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Golnar Taheri, Maryam Sardari, Dirk M. Hermann, and Houri Sepehri
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focal cerebral ischemia ,ischemic stroke ,neuroinflammantion ,neurological deficits ,sepsis ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Infection is a major reason for poor stroke outcomes, and sepsis is a major cause of stroke-elated deaths. We herein examined whether NMDA receptor blockade, which was reported to exert anti-inflammatory actions, protects against the deleterious consequences of lipopolysaccharide (LPS)-induced sepsis-like state in adult male NMRI mice exposed to transient intraluminal middle cerebral artery occlusion (MCAO). At 24 h post-ischemia, vehicle or Escherichia coli LPS (2 or 4 mg/kg) was intraperitoneally administered, whereas 30 min later vehicle or ketamine (10 mg/kg), which is a non-competitive NMDA receptor antagonist, was intraperitoneally applied. Delivery of LPS at a dosage of 4 mg/kg induced a sepsis-like state characterized by a rectal temperature reduction by ∼4.0°C, increased neurological deficits in Clark score, cylinder and open-field tests, increased brain infarct volume and reduced neuronal survival in the previously ischemic tissue. Notably, additional treatment with ketamine (10 mg/kg) significantly attenuated the sepsis-associated rectal temperature reduction by ∼1.5°C, reduced neurological deficits, reduced infarct volume, and promoted neuronal survival. Ketamine alone did not influence infarct volume or neurological deficits. Real-time PCR data analysis showed that GFAP, CD86, CD206, IL-1β, and IL-10 mRNA levels were significantly increased in ischemic brains of LPS-treated compared with vehicle-treated mice. Additional treatment with ketamine significantly decreased IL-1β and IL-10, but not GFAP, CD86, and CD206 mRNA levels. Our data show that ketamine at a dose that on its own does not confer neuroprotection reverses the adverse effects of LPS-induced sepsis-like state post-ischemia, presumably via immunomodulatory actions.
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- 2022
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55. Editorial: Hot Topics in Cellular Neuropathology
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Dirk M. Hermann, Aurel Popa-Wagner, Luca Peruzzotti-Jametti, and Matthias Gunzer
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neurodegeneration ,neuroinflammation ,microglia ,cognitive deficits ,dementia ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Published
- 2022
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56. A Lagrangian analysis of the dynamical and thermodynamic drivers of large-scale Greenland melt events during 1979–2017
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M. Hermann, L. Papritz, and H. Wernli
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Meteorology. Climatology ,QC851-999 - Abstract
In this study, we systematically investigate the dynamical and thermodynamic processes that lead to 77 large-scale melt events affecting high-elevation regions of the Greenland Ice Sheet (GrIS) in June–August (JJA) 1979–2017. For that purpose, we compute 8 d kinematic backward trajectories from the lowermost ∼500 m above the GrIS during these events. The key synoptic feature accompanying the melt events is an upper-tropospheric ridge southeast of the GrIS associated with a surface high-pressure system. This circulation pattern is favorable to induce rapid poleward transport (up to 40∘ latitude) of warm (∼15 K warmer than climatological air masses arriving on the GrIS) and moist air masses from the lower troposphere to the western GrIS and subsequently to distribute them in the anticyclonic flow over north and east Greenland. During transport to the GrIS, the melt event air masses cool by ∼15 K due to ascent and radiation, which keeps them just above the critical threshold to induce melting. The thermodynamic analyses reveal that the final warm anomaly of the air masses is primarily owed to anomalous horizontal transport from a climatologically warm region of origin. However, before being transported to the GrIS, i.e., in their region of origin, these air masses were not anomalously warm. Latent heating from condensation of water vapor, occurring as the airstreams are forced to ascend orographically or dynamically, is of secondary importance. These characteristics were particularly pronounced during the most extensive melt event in early July 2012, where, importantly, the warm anomaly was not preserved from anomalously warm source regions such as North America experiencing a record heat wave. The mechanisms identified here are in contrast to melt events in the low-elevation high Arctic and to midlatitude heat waves, where adiabatic warming by large-scale subsidence is essential. Considering the impact of moisture on the surface energy balance, we find that radiative effects are closely linked to the air mass trajectories and enhance melt over the entire GrIS accumulation zone due to (i) enhanced downward longwave radiation related to poleward moisture transport and a shift in the cloud phase from ice to liquid primarily west of the ice divide and (ii) increased shortwave radiation in clear-sky regions east of the ice divide. Given the ongoing increase in the frequency and the melt extent of large-scale melt events, the understanding of upper-tropospheric ridges over the North Atlantic, i.e., also Greenland blocking, and its representation in climate models is crucial in determining future GrIS accumulation zone melt and thus global sea level rise.
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- 2020
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57. SELF-SUPERVISED LEARNING FOR MONOCULAR DEPTH ESTIMATION FROM AERIAL IMAGERY
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M. Hermann, B. Ruf, M. Weinmann, and S. Hinz
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Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Applied optics. Photonics ,TA1501-1820 - Abstract
Supervised learning based methods for monocular depth estimation usually require large amounts of extensively annotated training data. In the case of aerial imagery, this ground truth is particularly difficult to acquire. Therefore, in this paper, we present a method for self-supervised learning for monocular depth estimation from aerial imagery that does not require annotated training data. For this, we only use an image sequence from a single moving camera and learn to simultaneously estimate depth and pose information. By sharing the weights between pose and depth estimation, we achieve a relatively small model, which favors real-time application. We evaluate our approach on three diverse datasets and compare the results to conventional methods that estimate depth maps based on multi-view geometry. We achieve an accuracy δ1:25 of up to 93.5 %. In addition, we have paid particular attention to the generalization of a trained model to unknown data and the self-improving capabilities of our approach. We conclude that, even though the results of monocular depth estimation are inferior to those achieved by conventional methods, they are well suited to provide a good initialization for methods that rely on image matching or to provide estimates in regions where image matching fails, e.g. occluded or texture-less regions.
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- 2020
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58. Decreasing trends of particle number and black carbon mass concentrations at 16 observational sites in Germany from 2009 to 2018
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J. Sun, W. Birmili, M. Hermann, T. Tuch, K. Weinhold, M. Merkel, F. Rasch, T. Müller, A. Schladitz, S. Bastian, G. Löschau, J. Cyrys, J. Gu, H. Flentje, B. Briel, C. Asbach, H. Kaminski, L. Ries, R. Sohmer, H. Gerwig, K. Wirtz, F. Meinhardt, A. Schwerin, O. Bath, N. Ma, and A. Wiedensohler
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Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Anthropogenic emissions are dominant contributors to air pollution. Consequently, mitigation policies have been attempted since the 1990s in Europe to reduce pollution by anthropogenic emissions. To evaluate the effectiveness of these mitigation policies, the German Ultrafine Aerosol Network (GUAN) was established in 2008, focusing on black carbon (BC) and sub-micrometre aerosol particles. In this study, long-term trends of atmospheric particle number concentrations (PNCs) and equivalent BC (eBC) mass concentration over a 10-year period (2009–2018) were determined for 16 GUAN sites ranging from roadside to high Alpine environments. Overall, statistically significant decreasing trends are found for most of these parameters and environments in Germany. The annual relative slope of eBC mass concentration varies between −13.1 % and −1.7 % per year. The slopes of the PNCs vary from −17.2 % to −1.7 %, −7.8 % to −1.1 %, and −11.1 % to −1.2 % per year for 10–30, 30–200, and 200–800 nm size ranges, respectively. The reductions in various anthropogenic emissions are found to be the dominant factors responsible for the decreasing trends of eBC mass concentration and PNCs. The diurnal and seasonal variations in the trends clearly show the effects of the mitigation policies for road transport and residential emissions. The influences of other factors such as air masses, precipitation, and temperature were also examined and found to be less important or negligible. This study proves that a combination of emission mitigation policies can effectively improve the air quality on large spatial scales. It also suggests that a long-term aerosol measurement network at multi-type sites is an efficient and necessary tool for evaluating emission mitigation policies.
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- 2020
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59. Randomized Efficacy and Safety Trial with Oral S 44819 after Recent ischemic cerebral Event (RESTORE BRAIN study): a placebo controlled phase II study
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Hugues Chabriat, Claudio L. Bassetti, Ute Marx, Françoise Picarel-Blanchot, Aurore Sors, Celine Gruget, Barbara Saba, Marine Wattez, Marie-Laure Audoli, and Dirk M. Hermann
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S44819 ,Ischemic cerebral stroke ,Efficacy ,Safety ,Study design ,GABA ,Medicine (General) ,R5-920 - Abstract
Abstract Background The GABAA-α5 receptor antagonist S44819 is a promising candidate to enhance functional recovery after acute ischemic stroke (IS). S44819 is currently evaluated in this indication; RESTORE brain study started in Dec 2016 and was completed in March 2019. Methods/design The study is a 3-month international, randomized, double-blind, parallel group, placebo-controlled phase II multicentre study. Patients in 14 countries who suffered an IS leading to a moderate or severe deficit defined by NIHSS score ranging from 7 to 20 and are aged between 18 to 85 years are included between 3 and 8 days after the stroke onset. Approximately 580 patients are to be included. The primary objective of the study is to demonstrate the superiority of at least one of the two doses of S44819 (150 or 300 mg bid) compared to placebo on top of usual care on functional recovery measured with the modified Rankin scale at 3 months. Comparisons between two doses of S44819 and placebo are assessed with ordinal logistic regression evaluating the odds of shifting from one category to the next in the direction of a better outcome at day 90. Secondary objectives include the evaluation of S44819 effects on neurological examination using the National Institute of Health Stroke Scale total score, activities of daily living using the Barthel Index total score, and cognitive performance using the Montreal Cognitive Assessment scale total score and Trail Making Test times. Safety and tolerability of the two doses of S44819 will also be analyzed. Discussion The RESTORE BRAIN study might represent the first proof of concept study of an innovative therapeutic approach that is primarily based on enhancing functional recovery after IS. Trial registration Randomized Efficacy and Safety Trial with Oral S 44819 after Recent ischemic cerebral Event, an international, multi-centre, randomized, double-blind placebo-controlled phase II study. ClinicalTrials.gov, NCT02877615; Eudract 2016–001005-16. Registered 24 August 2016
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- 2020
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60. Clinical and functional patient characteristics predict medical needs in older patients at risk of functional decline
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Anne-Carina Scharf, Janine Gronewold, Christian Dahlmann, Jeanina Schlitzer, Andreas Kribben, Guido Gerken, Helmut Frohnhofen, Richard Dodel, and Dirk M. Hermann
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Geriatrics ,RC952-954.6 - Abstract
Abstract Background The rising number of older multimorbid in-patients has implications for medical care. There is a growing need for the identification of factors predicting the needs of older patients in hospital environments. Our aim was to evaluate the use of clinical and functional patient characteristics for the prediction of medical needs in older hospitalized patients. Methods Two hundred forty-two in-patients (57.4% male) aged 78.4 ± 6.4 years, who were consecutively admitted to internal medicine departments of the University Hospital Essen between July 2015 and February 2017, were prospectively enrolled. Patients were assessed upon admission using the Identification of Seniors at Risk (ISAR) screening followed by comprehensive geriatric assessment (CGA). The CGA included standardized instruments for the assessment of activities of daily living (ADL), cognition, mobility, and signs of depression upon admission. In multivariable regressions we evaluated the association of clinical patient characteristics, the ISAR score and CGA results with length of hospital stay, number of nursing hours and receiving physiotherapy as indicators for medical needs. We identified clinical characteristics and risk factors associated with higher medical needs. Results The 242 patients spent [median(Q1;Q3)]:9.0(4.0;16.0) days in the hospital, needed 2.0(1.5;2.7) hours of nursing each day, and 34.3% received physiotherapy. In multivariable regression analyses including clinical patient characteristics, ISAR and CGA domains, the factors age (β = − 0.19, 95% confidence interval (CI) = − 0.66;-0.13), number of admission diagnoses (β = 0.28, 95% CI = 0.16;0.41), ADL impairment (B = 6.66, 95% CI = 3.312;10.01), and signs of depression (B = 6.69, 95% CI = 1.43;11.94) independently predicted length of hospital stay. ADL impairment (B = 1.14, 95%CI = 0.67;1.61), cognition impairment (B = 0.57, 95% CI = 0.07;1.07) and ISAR score (β =0.26, 95% CI = 0.01;0.28) independently predicted nursing hours. The number of admission diagnoses (risk ratio (RR) = 1.06, 95% CI = 1.04;1.08), ADL impairment (RR = 3.54, 95% CI = 2.29;5.47), cognition impairment (RR = 1.77, 95% CI = 1.20;2.62) and signs of depression (RR = 1.99, 95% CI = 1.39;2.85) predicted receiving physiotherapy. Conclusion Among older in-patients at risk for functional decline, the number of comorbidities, reduced ADL, cognition impairment and signs of depression are important predictors of length of hospital stay, nursing hours, and receiving physiotherapy during hospital stay.
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- 2020
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61. Functional relevance of the multi-drug transporter abcg2 on teriflunomide therapy in an animal model of multiple sclerosis
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Lisa Thiele née Schrewe, Kirsten Guse, Silvia Tietz, Jana Remlinger, Seray Demir, Xiomara Pedreiturria, Robert Hoepner, Anke Salmen, Maximilian Pistor, Timothy Turner, Britta Engelhardt, Dirk M. Hermann, Fred Lühder, Stefan Wiese, and Andrew Chan
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abcg2 ,Teriflunomide ,Multiple sclerosis ,Experimental autoimmune encephalomyelitis ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background The multi-drug resistance transporter ABCG2, a member of the ATP-binding cassette (ABC) transporter family, mediates the efflux of different immunotherapeutics used in multiple sclerosis (MS), e.g., teriflunomide (teri), cladribine, and mitoxantrone, across cell membranes and organelles. Hence, the modulation of ABCG2 activity could have potential therapeutic implications in MS. In this study, we aimed at investigating the functional impact of abcg2 modulation on teri-induced effects in vitro and in vivo. Methods T cells from C57BL/6 J wild-type (wt) and abcg2-knockout (KO) mice were treated with teri at different concentrations with/without specific abcg2-inhibitors (Ko143; Fumitremorgin C) and analyzed for intracellular teri concentration (HPLC; LS-MS/MS), T cell apoptosis (annexin V/PI), and proliferation (CSFE). Experimental autoimmune encephalomyelitis (EAE) was induced in C57BL/6J by active immunization with MOG35–55/CFA. Teri (10 mg/kg body weight) was given orally once daily after individual disease onset. abcg2-mRNA expression (spinal cord, splenic T cells) was analyzed using qRT-PCR. Results In vitro, intracellular teri concentration in T cells was 2.5-fold higher in abcg2-KO mice than in wt mice. Teri-induced inhibition of T cell proliferation was two fold increased in abcg2-KO cells compared to wt cells. T cell apoptosis demonstrated analogous results with 3.1-fold increased apoptosis after pharmacological abcg2-inhibition in wt cells. abcg2-mRNA was differentially regulated during different phases of EAE within the central nervous system and peripheral organs. In vivo, at a dosage not efficacious in wt animals, teri treatment ameliorated clinical EAE in abcg2-KO mice which was accompanied by higher spinal cord tissue concentrations of teri. Conclusion Functional relevance of abcg2 modulation on teri effects in vitro and in vivo warrants further investigation as a potential determinant of interindividual treatment response in MS, with potential implications for other immunotherapies.
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- 2020
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62. Editorial: Perspectives of Astrocytes in Neurodevelopmental and Neurodegenerative Diseases: From Mechanistic Studies to Therapeutic Applications
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Egor Dzyubenko, Dirk M. Hermann, and Junhui Wang
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neuropathology ,reactive astrocytes ,gliovascular unit ,neuron-glia interactions ,neurotoxic astrocyte ,hepatic encephalopathy (HE) ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Published
- 2022
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63. Lessons learned after one year of COVID-19 from a urologist and radiotherapist view: A German survey on prostate cancer diagnosis and treatment.
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Nina N Harke, Christian Wagner, Robert M Hermann, Boris A Hadaschik, Jan Philipp Radtke, Alev Altay-Langguth, Stefan Aufderklamm, Christian Bach, Martina Becker-Schiebe, Andreas Blana, Frank Bruns, Stephan Buse, Stephanie E Combs, Christina L Engels, Emad Ezzibdeh, Marcel Fiedler, Laura-Anna Fischer, Mahmoud Farzat, Alexander Frismann, Matthias M Heck, Christoph Henkenberens, Marie C Roesch, Christoph Käding, Gunther Klautke, Philipp Krausewitz, Markus A Kuczyk, Conrad Leitsmann, Sebastian Lettmaier, Samy Mahjoub, Andreas Manseck, Daniel Medenwald, Andreas Meyer, Oliver Micke, Rudolf Moritz, Marcel Ott, Inga Peters, Sasa Pokupic, Daniel Porres, Felix Preisser, Kathrin Reichel, Andreas Schneider, Christian Schwentner, Sergiu Scobioala, Michael Truss, Daniel Wegener, Felix Wezel, Kay Willborn, Jörn H Witt, Andrea Wittig, Michael Wittlinger, Hendrik A Wolff, Volker Zimmermanns, and Hans Christiansen
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Medicine ,Science - Abstract
IntroductionSince the beginning of the pandemic in 2020, COVID-19 has changed the medical landscape. International recommendations for localized prostate cancer (PCa) include deferred treatment and adjusted therapeutic routines.Materials and methodsTo longitudinally evaluate changes in PCa treatment strategies in urological and radiotherapy departments in Germany, a link to a survey was sent to 134 institutions covering two representative baseline weeks prior to the pandemic and 13 weeks from March 2020 to February 2021. The questionnaire captured the numbers of radical prostatectomies, prostate biopsies and case numbers for conventional and hypofractionation radiotherapy. The results were evaluated using descriptive analyses.ResultsA total of 35% of the questionnaires were completed. PCa therapy increased by 6% in 2020 compared to 2019. At baseline, a total of 69 radiotherapy series and 164 radical prostatectomies (RPs) were documented. The decrease to 60% during the first wave of COVID-19 particularly affected low-risk PCa. The recovery throughout the summer months was followed by a renewed reduction to 58% at the end of 2020. After a gradual decline to 61% until July 2020, the number of prostate biopsies remained stable (89% to 98%) during the second wave. The use of RP fluctuated after an initial decrease without apparent prioritization of risk groups. Conventional fractionation was used in 66% of patients, followed by moderate hypofractionation (30%) and ultrahypofractionation (4%). One limitation was a potential selection bias of the selected weeks and the low response rate.ConclusionWhile the diagnosis and therapy of PCa were affected in both waves of the pandemic, the interim increase between the peaks led to a higher total number of patients in 2020 than in 2019. Recommendations regarding prioritization and fractionation routines were implemented heterogeneously, leaving unexplored potential for future pandemic challenges.
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- 2022
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64. Association between life events and later depression in the population-based Heinz Nixdorf Recall study-The role of sex and optimism.
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Janine Gronewold, Ela-Emsal Duman, Miriam Engel, Miriam Engels, Johannes Siegrist, Raimund Erbel, K-H Jöckel, and Dirk M Hermann
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Medicine ,Science - Abstract
BackgroundThe association between life event stress and depressive symptoms has not been analyzed in the general population before.MethodsIn the population-based Heinz Nixdorf Recall study, we assessed the association of 1.) the presence of important life events and 2.) life event stress, with the amount of depressive symptoms in univariable linear regressions and in multivariable regressions adjusted for age and sex (model 1) and age, sex and optimism as important determinants of coping with life events (model 2). Presence of life events and life event stress were assessed with the Social Readjustment Rating Scale (SRRS), optimism with the Life Orientation Test-Revised (LOT-R), and depressive symptoms with the 15-item Center for Epidemiological Studies Depression Scale (CES-D).ResultsOf the total cohort of 4,814 participants, 1,120 had experienced important life events during the previous 6 months. Presence of important life events was significantly associated with higher CES-D scores (B = 2.6, 95%CI = 2.2 to 3.0, p < .001; model 2) compared to absence of life events. Associations were stronger for women than for men and for pessimists than for optimists. Among the participants with important life events, median (Q1; Q3) stress-score was 45.0 (39.0; 63.0). Stress-scores >Q3 were significantly associated with higher CES-D scores (2.2, 1.1 to 3.3, < .001) with a stronger association in pessimists than in optimists.ConclusionsExperiencing life-changing events is associated with depression. Women and individuals with pessimistic personality are especially vulnerable which should be considered in prevention strategies.
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- 2022
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65. Roles of Polymorphonuclear Neutrophils in Ischemic Brain Injury and Post-Ischemic Brain Remodeling
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Ayan Mohamud Yusuf, Nina Hagemann, Peter Ludewig, Matthias Gunzer, and Dirk M. Hermann
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focal cerebral ischemia ,ischemic stroke ,neuroinflammation ,brain remodeling ,polymorphonuclear neutrophils ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Following ischemic stroke, polymorphonuclear neutrophils (PMNs) are rapidly recruited to the ischemic brain tissue and exacerbate stroke injury by release of reactive oxygen species (ROS), proteases and proinflammatory cytokines. PMNs may aggravate post-ischemic microvascular injury by obstruction of brain capillaries, contributing to reperfusion deficits in the stroke recovery phase. Thus, experimental studies which specifically depleted PMNs by delivery of anti-Ly6G antibodies or inhibited PMN brain entry, e.g., by CXC chemokine receptor 2 (CXCR2) or very late antigen-4 (VLA-4) blockade in the acute stroke phase consistently reduced neurological deficits and infarct volume. Although elevated PMN responses in peripheral blood are similarly predictive for large infarcts and poor stroke outcome in human stroke patients, randomized controlled clinical studies targeting PMN brain infiltration did not improve stroke outcome or even worsened outcome due to serious complications. More recent studies showed that PMNs have decisive roles in post-ischemic angiogenesis and brain remodeling, most likely by promoting extracellular matrix degradation, thereby amplifying recovery processes in the ischemic brain. In this minireview, recent findings regarding the roles of PMNs in ischemic brain injury and post-ischemic brain remodeling are summarized.
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- 2022
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66. Circulating MicroRNAs and Extracellular Vesicle-Derived MicroRNAs as Predictors of Functional Recovery in Ischemic Stroke Patients: A Systematic Review and Meta-Analysis
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Codrin-Constantin Burlacu, Daniela Ciobanu, Andrei-Vlad Badulescu, Vlad-Florin Chelaru, Andrei-Otto Mitre, Bogdan Capitanescu, Dirk M. Hermann, and Aurel Popa-Wagner
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microRNAs ,extracellular vesicles ,disease biomarkers ,ischemic stroke ,prognosis ,stroke recovery ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Stroke accounts for the second leading cause of death and a major cause of disability, with limited therapeutic strategy in both the acute and chronic phases. Blood-based biomarkers are intensively researched and widely recognized as useful tools to predict the prognoses of patients confronted with therapeutically limited diseases. We performed a systematic review of the circulating biomarkers in IS patients with prognostic value, with a focus on microRNAs and exosomes as predictive biomarkers of motor and cognitive recovery. We identified 63 studies, totalizing 72 circulating biomarkers with prognostic value in stroke recovery, as follows: 68 miRNAs and exosomal-miRNAs being identified as predictive for motor recovery after stroke, and seven biomarkers being predictive for cognitive recovery. Twelve meta-analyses were performed using effect sizes (random-effects and fixed-effects model). The most significant correlation findings obtained after pooling were with miR-21, miR-29b, miR-125b-5p, miR-126, and miR-335. We identified several miRNAs that were correlated with clinical outcomes of stroke severity and recovery after ischemic stroke, providing predictive information on motor and cognitive recovery. Based on the current state of research, we identified serum miR-9 and neutrophil miR-29b as the most promising biomarkers for in-depth follow-up studies, followed by serum miR-124 and plasma miR-125b.
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- 2022
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67. Lost in the Translation Trap: Quest for a Research Reporting Culture That More Carefully Weighs Clinical Applicability in Experimental Disease Models
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Dirk M. Hermann
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clinical relevance ,human patient ,therapy ,animal model ,clinical translation ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Published
- 2021
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68. Inhibition of Fatty Acid Synthesis Aggravates Brain Injury, Reduces Blood-Brain Barrier Integrity and Impairs Neurological Recovery in a Murine Stroke Model
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Lisa Janssen, Xiaoyu Ai, Xuan Zheng, Wei Wei, Ahmet B. Caglayan, Ertugrul Kilic, Ya-chao Wang, Dirk M. Hermann, Vivek Venkataramani, Mathias Bähr, and Thorsten R. Doeppner
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blood-brain barrier ,cerebral ischemia ,fatty acid synthesis ,hypoxia ,neuroprotection ,reduction potential ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Inhibition of fatty acid synthesis (FAS) stimulates tumor cell death and reduces angiogenesis. When SH-SY5Y cells or primary neurons are exposed to hypoxia only, inhibition of FAS yields significantly enhanced cell injury. The pathophysiology of stroke, however, is not only restricted to hypoxia but also includes reoxygenation injury. Hence, an oxygen-glucose-deprivation (OGD) model with subsequent reoxygenation in both SH-SY5Y cells and primary neurons as well as a murine stroke model were used herein in order to study the role of FAS inhibition and its underlying mechanisms. SH-SY5Y cells and cortical neurons exposed to 10 h of OGD and 24 h of reoxygenation displayed prominent cell death when treated with the Acetyl-CoA carboxylase inhibitor TOFA or the fatty acid synthase inhibitor cerulenin. Such FAS inhibition reduced the reduction potential of these cells, as indicated by increased NADH2+/NAD+ ratios under both in vitro and in vivo stroke conditions. As observed in the OGD model, FAS inhibition also resulted in increased cell death in the stroke model. Stroke mice treated with cerulenin did not only display increased brain injury but also showed reduced neurological recovery during the observation period of 4 weeks. Interestingly, cerulenin treatment enhanced endothelial cell leakage, reduced transcellular electrical resistance (TER) of the endothelium and contributed to poststroke blood-brain barrier (BBB) breakdown. The latter was a consequence of the activated NF-κB pathway, stimulating MMP-9 and ABCB1 transporter activity on the luminal side of the endothelium. In conclusion, FAS inhibition aggravated poststroke brain injury as consequence of BBB breakdown and NF-κB-dependent inflammation.
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- 2021
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69. Analysing Intercellular Communication in Astrocytic Networks Using 'Astral'
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Egor Dzyubenko, Wojciech Prazuch, Matthias Pillath-Eilers, Joanna Polanska, and Dirk M. Hermann
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data analysis ,calcium imaging ,glia ,network coupling ,astrocyte-neuron interactions ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Astrocytic networks are critically involved in regulating the activity of neuronal networks. However, a comprehensive and ready-to-use data analysis tool for investigating functional interactions between the astrocytes is missing. We developed the novel software package named “Astral” to analyse intercellular communication in astrocytic networks based on live-cell calcium imaging. Our method for analysing calcium imaging data does not require the assignment of regions of interest. The package contains two applications: the core processing pipeline for detecting and quantifying Ca++ events, and the auxiliary visualization tool for controlling data quality. Our method allows for the network-wide quantification of Ca++ events and the analysis of their intercellular propagation. In a set of proof-of-concept experiments, we examined Ca++ events in flat monolayers of primary astrocytes and confirmed that inter-astrocytic interactions depend on the permeability of gap junctions and connexin hemichannels. The Astral tool is particularly useful for studying astrocyte-neuronal interactions on the network level. We demonstrate that compared with purely astrocytic cultures, spontaneous generation of Ca++ events in astrocytes that were co-cultivated with neurons was significantly increased. Interestingly, the increased astrocytic Ca++ activity after long-term co-cultivation with neurons was driven by the enhanced formation of gap junctions and connexin hemichannels but was not affected by silencing neuronal activity. Our data indicate the necessity for systematic investigation of astrocyte-neuronal interactions at the network level. For this purpose, the Astral software offers a powerful tool for processing and quantifying calcium imaging data.
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- 2021
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70. Duration of chemotherapy prior to chemoradiation affects survival outcomes for resected stage I‐II or unresected stage III pancreatic cancer
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Sung J. Ma, Austin J. Iovoli, Gregory M. Hermann, Kavitha M. Prezzano, and Anurag K. Singh
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induction ,locally advanced ,pancreas ,radiation ,resectable ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background For resected early stage pancreatic cancer, RTOG 9704 evaluated the outcome of 3 weeks of postoperative chemotherapy (C) followed by chemoradiation (CRT) and further C. For unresectable locally advanced pancreatic cancer, a recent literature review of prospective studies showed that the duration of induction C prior to CRT can impact survival. However, the ideal duration of C prior to CRT remains unclear for these patient cohorts. This National Cancer Database (NCDB) study was performed to compare the outcome of various durations of C prior to CRT. Methods The NCDB was queried for resected primary stage I‐II, cT1‐3N0‐1M0, and unresected stage III, cT4N0‐1M0 pancreatic adenocarcinoma treated with C + CRT (2004‐2015). Cohorts I‐II and III included stage I‐II and stage III cases, respectively. Patients were stratified by short (short C) and long duration (long C) of chemotherapy based on their median durations. Baseline patient, tumor, and treatment characteristics were examined. The primary endpoint was overall survival (OS). Kaplan‐Meier analysis, multivariable Cox proportional hazards method, and propensity score matching were used. Results Among 1577 patients, cohort I‐II had 839 patients and cohort III had 738 patients. The longer duration of chemotherapy prior to CRT showed improved OS in the multivariate analysis in both cohort I‐II (hazards ratio [HR] 0.72, P
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- 2019
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71. Health outcome of older hospitalized patients in internal medicine environments evaluated by Identification of Seniors at Risk (ISAR) screening and geriatric assessment
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Anne-Carina Scharf, Janine Gronewold, Christian Dahlmann, Jeanina Schlitzer, Andreas Kribben, Guido Gerken, Tienush Rassaf, Christoph Kleinschnitz, Richard Dodel, Helmut Frohnhofen, and Dirk M. Hermann
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ISAR ,CGA ,Older in-patients ,Risk screening ,Geriatrics ,Internal medicine ,RC952-954.6 - Abstract
Abstract Background Hospitals are in need of valid and economic screening and assessment tools that help identifying older patients at risk for complications which require intensified support during their hospital stay. Methods Five hundred forty-seven internal medicine in-patients (mean age 78.14 ± 5.96 years; 54.7% males) prospectively received Identification of Seniors at Risk (ISAR) screening. If screening results were positive (ISAR score ≥ 2), a comprehensive geriatric assessment (CGA) was performed. We explored sensitivity and specificity of different ISAR and CGA cutoffs. Further, we analyzed the risk of falls and how patients got discharged from hospital. Results ISAR+/CGA abnormal patients spent more days in hospital (16.1 ± 14.5), received more nursing hours per day (3.0 ± 2.3), more hours of physiotherapy during their hospital stay (2.2 ± 3.2), and had more falls (10.1%) compared to ISAR+/CGA normal (10.9 ± 12.3, 2.0 ± 1.2, 1.2 ± 4.3, and 2.8%, respectively, all p ≤ 0.016) and ISAR- (9.6 ± 11.5, 2.3 ± 4.5, 0.7 ± 2.0, and 2.2%, respectively, all p ≤ 0.002) patients. ISAR+/CGA abnormal patients terminated their treatment regularly with being discharged back home less often (59.6%) compared to ISAR+/CGA normal (78.5%, p = 0.002) and ISAR- (78.2%, p = 0.056) patients. ISAR cutoff≥2 and CGA defined as abnormal in case of impairment of ADL plus another CGA domain achieved best sensitivity/specificity. Conclusions Abnormal geriatric risk screening and assessment are associated with longer hospital stay and higher amount of nursing and physiotherapy during hospital stay, greater risk of falling, and a lower percentage of successfully terminated treatment in older in-patients.
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- 2019
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72. Contemporaneous 3D characterization of acute and chronic myocardial I/R injury and response
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Simon F. Merz, Sebastian Korste, Lea Bornemann, Lars Michel, Pia Stock, Anthony Squire, Camille Soun, Daniel R. Engel, Julia Detzer, Holger Lörchner, Dirk M. Hermann, Markus Kamler, Joachim Klode, Ulrike B. Hendgen-Cotta, Tienush Rassaf, Matthias Gunzer, and Matthias Totzeck
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Science - Abstract
Detailed characterization of cardiac damage following ischemia/reperfusion injury and detection of occurring inflammatory responses is important for the development of new therapeutic concepts. Here the authors present a method for the three-dimensional investigation of acute and chronic cardiac injury responses using light sheet fluorescence microscopy.
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- 2019
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73. Social isolation and risk of fatal cardiovascular events
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Janine Gronewold and Dirk M Hermann
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Public aspects of medicine ,RA1-1270 - Published
- 2021
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74. Light Sheet Microscopy Using FITC-Albumin Followed by Immunohistochemistry of the Same Rehydrated Brains Reveals Ischemic Brain Injury and Early Microvascular Remodeling
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Ayan Mohamud Yusuf, Nina Hagemann, Sarah Schulten, Olessja Rausch, Kristina Wagner, Tanja Hussner, Yachao Qi, Matthias Totzeck, Christoph Kleinschnitz, Anthony Squire, Matthias Gunzer, and Dirk M. Hermann
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angiography ,brain clearing ,capillary ,cerebral microvessels ,focal cerebral ischemia—reperfusion ,ischemic stroke ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Until recently, the visualization of cerebral microvessels was hampered by the fact that only short segments of vessels could be evaluated in brain sections by histochemistry. These limitations have been overcome by light sheet microscopy, which allows the 3D analysis of microvasculature in cleared brains. A major limitation of light sheet microscopy is that antibodies do not sufficiently penetrate cleared brains. We herein describe a technique of reverse clearing and rehydration, which after microvascular network analysis allows brain sectioning and immunohistochemistry employing a broad set of antibodies. Performing light sheet microscopy on brains of mice exposed to intraluminal middle cerebral artery occlusion (MCAO), we show that in the early phase of microvascular remodeling branching point density was markedly reduced, more strongly than microvascular length. Brain infarcts in light sheet microscopy were sharply demarcated by their autofluorescence signal, closely corresponding to brain infarcts revealed by Nissl staining. Neuronal survival, leukocyte infiltration, and astrocytic reactivity could be evaluated by immunohistochemistry in rehydrated brains, as shown in direct comparisons with non-cleared brains. Immunohistochemistry revealed microthrombi in ischemic microvessels that were likely responsible for the marked branching point loss. The balance between microvascular thrombosis and remodeling warrants further studies at later time-points after stroke.
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- 2021
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75. Modulating Microglial Cells for Promoting Brain Recovery and Repair
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Dirk M. Hermann and Matthias Gunzer
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blood-derived immune cell ,brain injury ,brain ischemia ,neuroimmunology ,neurodegeneration ,neuroplasticity ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Representing the brain’s innate immune cells that interact vividly with blood-derived immune cells and brain parenchymal cells, microglia set the stage for successful brain remodeling and repair in the aftermath of brain damage. With the development of pharmacological colony-stimulating factor-1 receptor inhibitors, which allow inhibiting or depleting microglial cells, and of transgenic mice, allowing the inducible depletion of microglial cells, experimental tools have become available for studying roles of microglia in neurodegenerative and neurorestorative processes. These models open fundamental insights into roles of microglia in controlling synaptic plasticity in the healthy and the injured brain. Acting as a switch from injury to repair, microglial cells might open opportunities for promoting neurological recovery in human patients upon brain injury.
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- 2021
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76. Hot Topics in Cellular Neuropathology
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Dirk M. Hermann
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neurology ,translational neuroscience ,neuropathology ,applied neuroscience ,clinical neuroscience ,therapy ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Published
- 2020
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77. Postacute administration of the GABA α5 antagonist S44819 promotes recovery of peripheral limb fine motor skills after permanent distal middle cerebral artery occlusion in rats
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Marta Pace, Matteo Falappa, Patricia Machado, Laura Facchin, Dirk M Hermann, and Claudio L Bassetti
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Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Background: Ischemic stroke causes hypoexcitability in the peri-infarct motor neocortex that stems from increased tonic γ-amino-butyric acid (GABA) activity in neurons. This hypoexcitability, while neuroprotective in the acute phase, may impair neuroplasticity and functional recovery in the subacute phase of stroke. The purpose of this study is to investigate the effect of delayed and prolonged administration of S44819, which is a potent and competitive selective antagonist of GABA A receptors, on the skilled reaching function in a rodent model of stroke. Methods: Male Sprague–Dawley rats ( n = 15) were subjected to permanent middle cerebral artery occlusion. Starting 3 days after stroke, a vehicle or S44819 (3 or 10 mg/kg, BID) was delivered orally twice a day for 28 days. All animals were euthanized 2 weeks later after the washout period. A single pellet reaching task (SPR) was performed before (baseline value) and after the ischemic surgery at several time points (3, 10, 17, 24, 31, 38, and 45 days) to assess the motor deficit. Infarct volume and body changes were also evaluated. Results: S44819, administered at 10 but not 3 mg/kg, significantly improves SPR results over the 45 days after the ischemic surgery. No effect was observed in the infarct size and in the body weight over time between the groups investigated. Conclusion: S44819 at 10 mg/kg significantly enhances motor recovery on a skilled reaching task after sensory-motor cortex lesion. Additionally, our study, in light of the results of the RESTORE BRAIN (Randomized Efficacy and Safety Trial of Oral GABA A α5 antagonist S44819 after Recent ischemic Event) trial, may help clinicians to design clinical studies and stratify variables and patients adequately.
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- 2020
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78. Cell motility and migration as determinants of stem cell efficacy
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Lusine Danielyan, Matthias Schwab, Georg Siegel, Bianca Brawek, Olga Garaschuk, Nithi Asavapanumas, Marine Buadze, Ali Lourhmati, Hans-Peter Wendel, Meltem Avci-Adali, Marcel A. Krueger, Carsten Calaminus, Ulrike Naumann, Stefan Winter, Elke Schaeffeler, Annett Spogis, Sandra Beer-Hammer, Jonas J. Neher, Gabriele Spohn, Anja Kretschmer, Eva-Maria Krämer-Albers, Kerstin Barth, Hong Jun Lee, Seung U. Kim, William H. Frey, II, Claus D. Claussen, Dirk M. Hermann, Thorsten R. Doeppner, Erhard Seifried, Christoph H. Gleiter, Hinnak Northoff, and Richard Schäfer
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Mesenchymal stem cells ,Neural stem cells ,Intranasal ,Alzheimer´s disease ,Oncovirolysis ,Glioblastoma ,Medicine ,Medicine (General) ,R5-920 - Abstract
Background: Stem cells` (SC) functional heterogeneity and its poorly understood aetiology impedes clinical development of cell-based therapies in regenerative medicine and oncology. Recent studies suggest a strong correlation between the SC migration potential and their therapeutic efficacy in humans. Designating SC migration as a denominator of functional SC heterogeneity, we sought to identify highly migrating subpopulations within different SC classes and evaluate their therapeutic properties in comparison to the parental non-selected cells. Methods: We selected highly migrating subpopulations from mesenchymal and neural SC (sMSC and sNSC), characterized their features including but not limited to migratory potential, trophic factor release and transcriptomic signature. To assess lesion-targeted migration and therapeutic properties of isolated subpopulations in vivo, surgical transplantation and intranasal administration of MSCs in mouse models of glioblastoma and Alzheimer's disease respectively were performed. Findings: Comparison of parental non-selected cells with isolated subpopulations revealed superior motility and migratory potential of sMSC and sNSC in vitro. We identified podoplanin as a major regulator of migratory features of sMSC/sNSC. Podoplanin engineering improved oncovirolytic activity of virus-loaded NSC on distantly located glioblastoma cells. Finally, sMSC displayed more targeted migration to the tumour site in a mouse glioblastoma model and remarkably higher potency to reduce pathological hallmarks and memory deficits in transgenic Alzheimer's disease mice. Interpretation: Functional heterogeneity of SC is associated with their motility and migration potential which can serve as predictors of SC therapeutic efficacy. Funding: This work was supported in part by the Robert Bosch Stiftung (Stuttgart, Germany) and by the IZEPHA grant.
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- 2020
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79. Modulating endothelial adhesion and migration impacts stem cell therapies efficacy
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Richard Schäfer, Matthias Schwab, Georg Siegel, Andreas von Ameln-Mayerhofer, Marine Buadze, Ali Lourhmati, Hans-Peter Wendel, Torsten Kluba, Marcel A. Krueger, Carsten Calaminus, Eva Scheer, Massimo Dominici, Giulia Grisendi, Thorsten R. Doeppner, Jana Schlechter, Anne Kathrin Finzel, Dominic Gross, Roland Klaffschenkel, Frank K. Gehring, Gabriele Spohn, Anja Kretschmer, Karen Bieback, Eva-Maria Krämer-Albers, Kerstin Barth, Anne Eckert, Stefanie Elser, Joerg Schmehl, Claus D. Claussen, Erhard Seifried, Dirk M. Hermann, Hinnak Northoff, and Lusine Danielyan
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Stem cells ,Migration ,Adhesion ,Homing ,Stroke ,Glioma ,Medicine ,Medicine (General) ,R5-920 - Abstract
Background: Limited knowledge of stem cell therapies` mechanisms of action hampers their sustainable implementation into the clinic. Specifically, the interactions of transplanted stem cells with the host vasculature and its implications for their therapeutic efficacy are not elucidated. We tested whether adhesion receptors and chemokine receptors on stem cells can be functionally modulated, and consequently if such modulation may substantially affect therapeutically relevant stem cell interactions with the host endothelium. Methods: We investigated the effects of cationic molecule polyethylenimine (PEI) treatment with or without nanoparticles on the functions of adhesion receptors and chemokine receptors of human bone marrow-derived Mesenchymal Stem Cells (MSC). Analyses included MSC functions in vitro, as well as homing and therapeutic efficacy in rodent models of central nervous system´s pathologies in vivo. Findings: PEI treatment did not affect viability, immunomodulation or differentiation potential of MSC, but increased the CCR4 expression and functionally blocked their adhesion receptors, thus decreasing their adhesion capacity in vitro. Intravenously applied in a rat model of brain injury, the homing rate of PEI-MSC in the brain was highly increased with decreased numbers of adherent PEI-MSC in the lung vasculature. Moreover, in comparison to untreated MSC, PEI-MSC featured increased tumour directed migration in a mouse glioblastoma model, and superior therapeutic efficacy in a murine model of stroke. Interpretation: Balanced stem cell adhesion and migration in different parts of the vasculature and tissues together with the local microenvironment impacts their therapeutic efficacy. Funding: Robert Bosch Stiftung, IZEPHA grant, EU grant 7 FP Health
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- 2020
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80. Long-term exposure to ambient source-specific particulate matter and its components and incidence of cardiovascular events – The Heinz Nixdorf Recall study
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Vitalijs Rodins, Sarah Lucht, Simone Ohlwein, Frauke Hennig, Vanessa Soppa, Raimund Erbel, Karl-Heinz Jöckel, Christian Weimar, Dirk M. Hermann, Sara Schramm, Susanne Moebus, Uta Slomiany, and Barbara Hoffmann
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Air pollution ,Cardiovascular health ,Stroke ,Coronary heart disease ,Particulate matter ,Components ,Environmental sciences ,GE1-350 - Abstract
Background: Few studies have examined the risk of long-term exposure to source-specific airborne pollutants on incidence of cerebrovascular and cardiovascular events. Objectives: We aimed to estimate the effect of long-term exposure to source-specific air pollution and particulate matter (PM) components on incidence of stroke, coronary heart disease (CHD), and total cardiovascular events (CVE) in the population-based Heinz Nixdorf Recall study (HNR). Methods: We used baseline (2000–2003) and 14-year follow-up data of the HNR Study, an ongoing population-based prospective cohort study in Western Germany. Participants’ residential mean exposures to NO2 and total and source-specific PM10, PM2.5, accumulation mode particle number concentration (PNAM), and PM components were modelled using a dispersion and chemical transport model. We used Cox regression to evaluate the effect of pollutants (per 1 μg/m3 increase and per interquartile range – IQR) on risk of stroke and CHD, adjusting for socio-demographic characteristics, lifestyle risk factors and nighttime traffic noise exposure. Results: In 4,105 included participants (aged 45–76 at baseline, 52.5% women), we observed 118 cases of first stroke and 373 cases of first CHD during 46,748 person-years under risk. The median survival time within the cohort was 13.3 years. No effect of exposure to ambient air pollution on risk of CHD was observed, but distinct effects were observed for stroke. Ambient traffic-specific PM showed a stronger effect on stroke than industry-specific PM: hazard ratios (95% confidence interval) for total, traffic-specific, and industry-specific PM2.5 were 1.16 (1.02–1.34), 2.53 (1.07–5.97), and 1.27 (1.03–1.56) per 1 μg/m3 increase, respectively. PM components showed no substantially different effects from those of total PM per IQR, but higher associations were observed for NH4 and SO4 per 1 μg/m3. However, the exposure contrast of ammonium and sulfate components was very low. Conclusion: Traffic-specific PM exhibited stronger effects than total and industry-specific PM on risk of stroke. Among components, NH4 and SO4 showed higher effects. No effect was observed for PM and CHD.
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- 2020
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81. Electric Stimulation of Neurogenesis Improves Behavioral Recovery After Focal Ischemia in Aged Rats
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Adrian Tudor Balseanu, Monica Grigore, Leonard-Radu Pinosanu, Mark Slevin, Dirk M. Hermann, Daniela Glavan, and Aurel Popa-Wagner
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stroke ,aging ,rats ,electrical stimulation ,neurogenesis ,behavior ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
The major aim of stroke therapies is to stimulate brain repair and to improve behavioral recuperation after cerebral ischemia. Despite remarkable advances in cell therapy for stroke, stem cell-based tissue replacement has not been achieved yet stimulating the search for alternative strategies for brain self-repair using the neurogenic zones of the brain, the dentate gyrus and the subventricular zone (SVZ). However, during aging, the potential of the hippocampus and the SVZ to generate new neuronal precursors, declines. We hypothesized that electrically stimulation of endogenous neurogenesis in aged rats could increase the odds of brain self-repair and improve behavioral recuperation after focal ischemia. Following stroke in aged animals, the rats were subjected to two sessions of electrical non-convulsive stimulation using ear-clip electrodes, at 7- and 24 days after MCAO. Animal were sacrificed after 48 days. We report that electrical stimulation (ES) stimulation of post-stroke aged rats led to an improved functional recovery of spatial long-term memory (T-maze) but not on the rotating pole or the inclined plane, both tests requiring complex sensorimotor skills. Surprisingly, ES had a detrimental effect on the asymmetric sensorimotor deficit. Histologically, there was a robust increase in the number of doublecortin-positive cells in the dentate gyrus and SVZ of the infarcted hemisphere and the presence of a considerable number of neurons expressing tubulin beta III in the infarcted area. Among the gene that were unique to ES, we noted increases in the expression of seizure related 6 homolog like which is one of the physiological substrate of the β-secretase BACE1 involved in the pathophysiology of the Alzheimer’s disease and Igfbp3 and BDNF receptor mRNAs which has been shown to have a neuroprotective effect after cerebral ischemia. However, ES was associated with a long-term down regulation of cortical gene expression after stroke in aged rats suggesting that gene expression in the peri-infarcted cortical area may not be related to electrical stimulation induced-neurogenesis in the subventricular zone and hippocampus.
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- 2020
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82. Dose-Dependent Microglial and Astrocytic Responses Associated With Post-ischemic Neuroprotection After Lipopolysaccharide-Induced Sepsis-Like State in Mice
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Maryam Sardari, Egor Dzyubenko, Ben Schmermund, Dongpei Yin, Yachao Qi, Christoph Kleinschnitz, and Dirk M. Hermann
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microglial activation ,middle cerebral artery occlusion ,neuroprotection ,morphological analysis ,reactive astrocyte ,sepsis ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
In contrast to lipopolysaccharide (LPS)-induced preconditioning, which has repeatedly been examined in the past, the effects of post-ischemic LPS-induced sepsis, although clinically considerably more important, have not systemically been studied. We exposed mice to transient intraluminal middle cerebral artery occlusion (MCAO) and examined the effects of intraperitoneal LPS (0.1 or 1 mg/kg) which was administered 24 h post-ischemia. Post-ischemic glial reactivity, neuronal survival and neurological outcome were differently modulated by the higher and the lower LPS dose. Although both doses promoted neuronal survival after 72 h, the underlying mechanisms were not similar. Mice receiving 1 mg/kg LPS exhibited transient hypothermia at 1 and 3 hours post sepsis (hps), followed by reduced focal neurological deficits at 24, 48 and 72 hps. The lower dose (0.1 mg/kg) did not induce hypothermia, but reduced microglia/macrophage activation with the appearance of an anti-inflammatory CD206 positive cell phenotype in the brain parenchyma. Together, our results indicate a novel, dose-dependent modulation of microglial cells that is intricately involved in brain protection.
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- 2020
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83. A pilot study of stereotactic body radiation therapy (SBRT) after surgery for stage III non-small cell lung cancer
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Anurag K. Singh, Mark Hennon, Sung Jun Ma, Todd L. Demmy, Anthony Picone, Elizabeth U. Dexter, Chumy Nwogu, Kristopher Attwood, Wei Tan, Gregory M. Hermann, Simon Fung-Kee-Fung, Harish K. Malhotra, Sai Yendamuri, and Jorge A. Gomez-Suescun
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Post-operative ,Adjuvant ,SABR ,RT ,Mediastinum ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background Standard therapy for stage III non-small cell lung cancer with chemotherapy and conventional radiation has suboptimal outcomes. We hypothesized that a combination of surgery followed by stereotactic body radiation therapy (SBRT) would be a safe alternative. Methods Patients with stage IIIA (multistation N2) or IIIB non-small cell lung cancer were enrolled from March 2013 to December 2015. The protocol included transcervical extended mediastinal lymphadenectomy (TEMLA) followed by surgical resection, 10 Gy SBRT directed to the involved mediastinum/hilar stations and/or positive surgical margins, and adjuvant systemic therapy. Patients not suitable for anatomic lung resection were treated with 30 Gy to the primary tumor. The primary efficacy end-point was the proportion of patients with grade 3 or higher adverse events (AE) or toxicities. Results Of 10 patients, 7 patients underwent neoadjuvant chemotherapy. All patients had TEMLA. Nine of 10 patients underwent surgical resection. The remaining patient had an unresectable tumor and received 30 Gy SBRT to the primary lesion. All patients had post-operative SBRT. Median follow-up was 18 months. There were no perioperative mortalities. Six patients had any grade 3 AEs with no grade 4–5 AEs. Of these, 4 were not attributable to radiation. Pulmonary-related grade 3 AEs were experienced by 2 patients. There were no failures within the 10 Gy volume. Overall survival and progression-free survival rates at 2 years were 68% (90% CI 36–86) and 40% (90% CI 16–63), respectively. Conclusions In carefully selected patients with locally advanced non-small cell lung cancer, combining surgery with SBRT was well tolerated with no local failure. Trial registration ClinicalTrials.gov identifying number NCT01781741. Registered February 1, 2013.
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- 2018
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84. Dose escalation of radiation therapy with or without induction chemotherapy for unresectable locally advanced pancreatic cancer
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Sung Jun Ma, Kavitha M. Prezzano, Gregory M. Hermann, and Anurag K. Singh
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Induction chemotherapy ,Locally advanced pancreatic cancer ,Dose escalation ,Conventionally fractionated ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background Dose escalation of conventionally fractionated radiation therapy (CFRT) above 45–54 Gy has an unclear survival benefit. Prior National Cancer Database (NCDB) analyses have shown improved overall survival with induction chemotherapy (iC) prior to concurrent chemoradiation (CRT) in locally advanced pancreatic cancer. Our study compared dose-escalated CFRT with and without iC. Methods The NCDB was queried for primary stage III, cT4 N0–1 M0 LAPC treated with CRT with or without iC (2004–2015). CFRT was stratified by
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- 2018
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85. Very Low Efficiency of Direct Reprogramming of Astrocytes Into Neurons in the Brains of Young and Aged Mice After Cerebral Ischemia
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Andrei Gresita, Daniela Glavan, Ion Udristoiu, Bogdan Catalin, Dirk M. Hermann, and Aurel Popa-Wagner
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aging ,cerebral ischemia ,therapy ,glial scar ,genetic conversion ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
After cerebral ischemia, the ratio between astroglial cells and neurons in the neurovascular unit is disrupted in the perilesional area. We hypothesized that restoring the balance within the neurovascular unit may lead to an improved neurorestoration after focal ischemia. Recently, an innovative technology has been invented to efficiently convert proliferating astroglial cells into neurons in the injured young brain. However, the conversion efficacy of this technology has not been explored in the post-stroke brains of the aged rodents. To this end, we used a retroviral delivery system encoding the transcription factor Ngn2 alone or in combination with the antiapoptotic factor Bcl-2 to target proliferating astrocytes in the neocortex of young and aged mice after cerebral ischemia. Successful direct in vivo reprogramming of reactive glia into neuroblasts and mature neurons was assessed by cellular phenotyping. We found that the conversion efficacy of proliferating astrocytes into neurons after cerebral ischemia in young and aged mice is disappointingly low, most likely because the therapeutic vectors carrying the conversion gene are engulfed by phagocytes shortly after intracortical administration. We conclude that other viral vectors and combinations of transcription factors should be employed to improve the efficacy of glia-to-neuron conversion after stroke in young and aged rodents.
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- 2019
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86. Mercury distribution in the upper troposphere and lowermost stratosphere according to measurements by the IAGOS-CARIBIC observatory: 2014–2016
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F. Slemr, A. Weigelt, R. Ebinghaus, J. Bieser, C. A. M. Brenninkmeijer, A. Rauthe-Schöch, M. Hermann, B. G. Martinsson, P. van Velthoven, H. Bönisch, M. Neumaier, A. Zahn, and H. Ziereis
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Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Mercury was measured onboard the IAGOS-CARIBIC passenger aircraft from May 2005 until February 2016 during near monthly sequences of mostly four intercontinental flights from Germany to destinations in North and South America, Africa and South and East Asia. Most of these mercury data were obtained using an internal default signal integration procedure of the Tekran instrument but since April 2014 more precise and accurate data were obtained using post-flight manual integration of the instrument raw signal. In this paper we use the latter data.Increased upper tropospheric total mercury (TM) concentrations due to large scale biomass burning were observed in the upper troposphere (UT) at the equator and southern latitudes during the flights to Latin America and South Africa in boreal autumn (SON) and boreal winter (DJF). TM concentrations in the lowermost stratosphere (LMS) decrease with altitude above the thermal tropopause but the gradient is less steep than reported before. Seasonal variation of the vertical TM distribution in the UT and LMS is similar to that of other trace gases with surface sources and stratospheric sinks. Speciation experiments suggest comparable TM and gaseous elementary mercury (GEM) concentrations at and below the tropopause leaving little space for Hg2+ (TM − GEM) being the dominating component of TM here. In the stratosphere significant GEM concentrations were found to exist up to 4 km altitude above the thermal tropopause. Correlations with N2O as a reference tracer suggest stratospheric lifetimes of 72±37 and 74±27 years for TM and GEM, respectively, comparable to the stratospheric lifetime of COS. This coincidence, combined with pieces of evidence from us and other researchers, corroborates the hypothesis that Hg2+ formed by oxidation in the stratosphere attaches to sulfate particles formed mainly by oxidation of COS and is removed with them from the stratosphere by air mass exchange, gravitational sedimentation and cloud scavenging processes.
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- 2018
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87. Airborne observations of newly formed boundary layer aerosol particles under cloudy conditions
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B. Altstädter, A. Platis, M. Jähn, H. Baars, J. Lückerath, A. Held, A. Lampert, J. Bange, M. Hermann, and B. Wehner
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Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
This study describes the appearance of ultrafine boundary layer aerosol particles under classical non-favourable conditions at the research site of TROPOS (Leibniz Institute for Tropospheric Research). Airborne measurements of meteorological and aerosol properties of the atmospheric boundary layer (ABL) were repeatedly performed with the unmanned aerial system ALADINA (Application of Light-weight Aircraft for Detecting IN-situ Aerosol) during three seasons between October 2013 and July 2015. More than 100 measurement flights were conducted on 23 different days with a total flight duration of 53 h. In 26 % of the cases, maxima of ultrafine particles were observed close to the inversion layer at altitudes between 400 and 600 m and the particles were rapidly mixed vertically and mainly transported downwards during short time intervals of cloud gaps. This study focuses on two measurement days affected by low-level stratocumulus clouds, but different wind directions (NE, SW) and minimal concentrations (−3) of SO2, as a common indicator for precursor gases at ground. Taken from vertical profiles, the onset of clouds led to a non-linearity of humidity that resulted in an increased turbulence at the local-scale and caused fast nucleation e.g., but in relation to rapid dilution of surrounding air, seen in sporadic clusters of ground data, so that ultrafine particles disappeared in the verticality. The typical banana shape of new particle formation (NPF) and growth was not seen at ground and thus these days might not have been classified as NPF event days by pure surface studies.
- Published
- 2018
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88. Analysis and characterization of tin-doped ZnO nanostructures
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null M. Hermann, null F. Bansil, and null H.A. Hunter
- Abstract
In this paper, undoped and tin-doped ZnO nanostructures were grown onto non-conductive substrates by a simple solution method. Structural, morphological, optical and electrical properties of the structures were investigated with respect to tin concentration. From XRD studies, all the ZnO nanostructures were found as hexagonal wurtzite type structures growing preponderantly oriented with c-axis nor- mal to the substrate. An increase in tin content resulted in a decrease in grain size, whereas the dislocation density in- creases. SEM observations indicated that all the structures were textured throughout the substrates without any cracks or pores. The influence of incorporation of tin on surface morphology of the samples was clearly seen. Average diameter of the nanostructures decreased with increasing tin content. Absorption spectra of the structures revealed that the band gap of the films increases with increasing tin concentration. It is found that the tin-doped samples have higher average transmittance than the undoped one. The 1 % tin-doped sample exhibited ∼80 % average transparency, which was the best transparency among the doped samples. Electrical measurements showed that resistivity of the structures increased with increasing dopant concentration. This increasing was attributed due to a decrease in carrier con- centration caused by carrier traps at the grain boundaries.
- Published
- 2022
89. Lässt sich die Therapie bei HPV-assoziierten Oropharynxkarzinomen deeskalieren?
- Author
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Robert M. Hermann and Hans Christiansen
- Subjects
General Earth and Planetary Sciences ,General Environmental Science - Published
- 2022
90. The Need for New Biomarkers to Assist with Stroke Prevention and Prediction of Post-Stroke Therapy Based on Plasma-Derived Extracellular Vesicles
- Author
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Mircea Popescu Driga, Bogdan Catalin, Denisa Greta Olaru, Agnieszka Slowik, Nikolaus Plesnila, Dirk M. Hermann, and Aurel Popa-Wagner
- Subjects
cerebral ischemia ,neurovascular unit ,aging ,exosomes ,biomarkers ,therapy ,Biology (General) ,QH301-705.5 - Abstract
The risk of having a stroke event doubles each decade after the age of 55. Therefore, it is of great interest to develop neurorestorative therapies of stroke which occurs mostly in elderly people. However, to date, patients at risk for these sequels of stroke are not duly diagnosed and treated due to the lack of reliable biomarkers. Extracellular vesicles (EVs) are lipid bilayer-delimited particles that are shed by the brain cells and are able to cross the blood–brain barrier and enter the blood stream; thus, they may be used to interrogate molecular and cellular events in the brain damaged area. In this review, we summarize the major molecular and cellular responses of astroglia and neurons to cerebral ischemia and assess their impact on post-stroke recovery and rehabilitation. In particular, we ask if EVs secreted by brain cells are responses to cerebral ischemia, and they may shed new light on the interplay between exosomes-mediated interactions between brain cells and the question of how to exploit it in order to predict the individual course of the disease and to introduce specific preventive or therapeutic strategies. Given these findings, we are left with two options: either to (i) transplant neuronal precursors into the damaged cortical area or (ii) to covert abundantly present proliferating astrocytes in the perilesional area into neurons by using recently developed genetic technologies. However, given the complexity of molecular and cellular responses to cerebral ischemia and our limited capabilities to restore brain structure and function, we are left with only one realistic aim: to invest more in prevention.
- Published
- 2021
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91. Particulate sulfur in the upper troposphere and lowermost stratosphere – sources and climate forcing
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B. G. Martinsson, J. Friberg, O. S. Sandvik, M. Hermann, P. F. J. van Velthoven, and A. Zahn
- Subjects
Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
This study is based on fine-mode aerosol samples collected in the upper troposphere (UT) and the lowermost stratosphere (LMS) of the Northern Hemisphere extratropics during monthly intercontinental flights at 8.8–12 km altitude of the IAGOS-CARIBIC platform in the time period 1999–2014. The samples were analyzed for a large number of chemical elements using the accelerator-based methods PIXE (particle-induced X-ray emission) and PESA (particle elastic scattering analysis). Here the particulate sulfur concentrations, obtained by PIXE analysis, are investigated. In addition, the satellite-borne lidar aboard CALIPSO is used to study the stratospheric aerosol load. A steep gradient in particulate sulfur concentration extends several kilometers into the LMS, as a result of increasing dilution towards the tropopause of stratospheric, particulate sulfur-rich air. The stratospheric air is diluted with tropospheric air, forming the extratropical transition layer (ExTL). Observed concentrations are related to the distance to the dynamical tropopause. A linear regression methodology handled seasonal variation and impact from volcanism. This was used to convert each data point into stand-alone estimates of a concentration profile and column concentration of particulate sulfur in a 3 km altitude band above the tropopause. We find distinct responses to volcanic eruptions, and that this layer in the LMS has a significant contribution to the stratospheric aerosol optical depth and thus to its radiative forcing. Further, the origin of UT particulate sulfur shows strong seasonal variation. We find that tropospheric sources dominate during the fall as a result of downward transport of the Asian tropopause aerosol layer (ATAL) formed in the Asian monsoon, whereas transport down from the Junge layer is the main source of UT particulate sulfur in the first half of the year. In this latter part of the year, the stratosphere is the clearly dominating source of particulate sulfur in the UT during times of volcanic influence and under background conditions.
- Published
- 2017
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92. Biochemical markers in vascular cognitive impairment associated with subcortical small vessel disease - A consensus report
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A. Wallin, E. Kapaki, M. Boban, S. Engelborghs, D. M. Hermann, B. Huisa, M. Jonsson, M. G. Kramberger, L. Lossi, B. Malojcic, S. Mehrabian, A. Merighi, E. B. Mukaetova-Ladinska, G. P. Paraskevas, B. O. Popescu, R. Ravid, L. Traykov, G. Tsivgoulis, G. Weinstein, A. Korczyn, M. Bjerke, and G. Rosenberg
- Subjects
Vascular cognitive impairment ,Subcortical small vessel disease ,Biomarkers ,Blood ,CSF ,Alzheimer’s disease ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
Abstract Background Vascular cognitive impairment (VCI) is a heterogeneous entity with multiple aetiologies, all linked to underlying vascular disease. Among these, VCI related to subcortical small vessel disease (SSVD) is emerging as a major homogeneous subtype. Its progressive course raises the need for biomarker identification and/or development for adequate therapeutic interventions to be tested. In order to shed light in the current status on biochemical markers for VCI-SSVD, experts in field reviewed the recent evidence and literature data. Method The group conducted a comprehensive search on Medline, PubMed and Embase databases for studies published until 15.01.2017. The proposal on current status of biochemical markers in VCI-SSVD was reviewed by all co-authors and the draft was repeatedly circulated and discussed before it was finalized. Results This review identifies a large number of biochemical markers derived from CSF and blood. There is a considerable overlap of VCI-SSVD clinical symptoms with those of Alzheimer’s disease (AD). Although most of the published studies are small and their findings remain to be replicated in larger cohorts, several biomarkers have shown promise in separating VCI-SSVD from AD. These promising biomarkers are closely linked to underlying SSVD pathophysiology, namely disruption of blood-CSF and blood–brain barriers (BCB-BBB) and breakdown of white matter myelinated fibres and extracellular matrix, as well as blood and brain inflammation. The leading biomarker candidates are: elevated CSF/blood albumin ratio, which reflects BCB/BBB disruption; altered CSF matrix metalloproteinases, reflecting extracellular matrix breakdown; CSF neurofilment as a marker of axonal damage, and possibly blood inflammatory cytokines and adhesion molecules. The suggested SSVD biomarker deviations contrasts the characteristic CSF profile in AD, i.e. depletion of amyloid beta peptide and increased phosphorylated and total tau. Conclusions Combining SSVD and AD biomarkers may provide a powerful tool to identify with greater precision appropriate patients for clinical trials of more homogeneous dementia populations. Thereby, biomarkers might promote therapeutic progress not only in VCI-SSVD, but also in AD.
- Published
- 2017
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93. C10ORF10/DEPP-mediated ROS accumulation is a critical modulator of FOXO3-induced autophagy
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S. Salcher, M. Hermann, U. Kiechl-Kohlendorfer, M. J. Ausserlechner, and P. Obexer
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DEPP ,FOXO3 ,Autophagy ,Reactive oxygen species ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background Neuroblastoma is the most common solid tumor in childhood and develops from undifferentiated progenitor cells of the sympathetic nervous system. In neuronal tumor cells DNA-damaging chemotherapeutic agents activate the transcription factor FOXO3 which regulates the formation of reactive oxygen species (ROS) and cell death as well as a longevity program associated with therapy resistance. We demonstrated before that C10ORF10/DEPP, a transcriptional target of FOXO3, localizes to peroxisomes and mitochondria and impairs cellular ROS detoxification. In the present study, we investigated the impact of FOXO3 and DEPP on the regulation of autophagy. Autophagy serves to reduce oxidative damage as it triggers a self-degradative process for the removal of aggregated or misfolded proteins and damaged organelles. Methods The effect of FOXO3 and DEPP on autophagy induction was analyzed using live cell fluorescence microscopy and immunoblot analyses of SH-EP cells transfected with a plasmid for EYFP-LC3 and with siRNAs specific for LC3, respectively. ROS steady-state levels were measured with reduced MitoTrackerRed CM-H2XROS. Cellular apoptosis was analyzed by flow cytometry and the caspase 3/7 assay. Results We report for the first time that DEPP induces ROS accumulation and thereby mediates the formation of autophagosomes as inhibition of ROS formation by N-acetyl-cysteine completely blocks autophagy. We further demonstrate that H2O2-treatment triggers autophagy-induction by FOXO3-mediated DEPP expression. Importantly, knockdown of DEPP was sufficient to efficiently inhibit autophagy-induction under different stress conditions such as serum starvation and genotoxic stress, suggesting that DEPP expression is critical for the initiation of autophagy in neuroblastoma. FOXO3-triggered autophagy partially protects neuroblastoma cells from cell death. Consistent with this concept, we demonstrate that inhibition of autophagy by LC3-knockdown significantly increased etoposide- and doxorubicin-induced apoptosis. These results were also confirmed by the use of the autophagy-inhibitor chloroquine that significantly enhanced the chemotherapeutic effect of etoposide and doxorubicin in neuronal tumor cells. Conclusion Targeting FOXO3/DEPP-triggered autophagy is a promising strategy to sensitize neuroblastoma cells to chemotherapy.
- Published
- 2017
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94. Deactivation of ATP-Binding Cassette Transporters ABCB1 and ABCC1 Does Not Influence Post-ischemic Neurological Deficits, Secondary Neurodegeneration and Neurogenesis, but Induces Subtle Microglial Morphological Changes
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Daniel Manrique-Castano, Maryam Sardari, Tayana Silva de Carvalho, Thorsten R. Doeppner, Aurel Popa-Wagner, Christoph Kleinschnitz, Andrew Chan, and Dirk M. Hermann
- Subjects
focal cerebral ischemia ,microglial morphology ,mouse ,multidrug resistance transporter ,neurodegeneration ,neurogenesis ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
ATP-binding cassette (ABC) transporters prevent the access of pharmacological compounds to the ischemic brain, thereby impeding the efficacy of stroke therapies. ABC transporters can be deactivated by selective inhibitors, which potently increase the brain accumulation of drugs. Concerns have been raised that long-term ABC transporter deactivation may promote neuronal degeneration and, under conditions of ischemic stroke, compromise neurological recovery. To elucidate this issue, we exposed male C57BL/6 mice to transient intraluminal middle cerebral artery occlusion (MCAO) and examined the effects of the selective ABCB1 inhibitor tariquidar (8 mg/kg/day) or ABCC1 inhibitor MK-571 (10 mg/kg/day), which were administered alone or in combination with each other over up to 28 days, on neurological recovery and brain injury. Mice were sacrificed after 14, 28, or 56 days. The Clark score, RotaRod, tight rope, and open field tests revealed reproducible motor-coordination deficits in mice exposed to intraluminal MCAO, which were not influenced by ABCB1, ABCC1, or combined ABCB1 and ABCC1 deactivation. Brain volume, striatum volume, and corpus callosum thickness were not altered by ABCB1, ABCC1 or ABCB1, and ABCC1 inhibitors. Similarly, neuronal survival and reactive astrogliosis, evaluated by NeuN and GFAP immunohistochemistry in the ischemic striatum, were unchanged. Iba1 immunohistochemistry revealed no changes of the overall density of activated microglia in the ischemic striatum of ABC transporter inhibitor treated mice, but subtle changes of microglial morphology, that is, reduced microglial cell volume by ABCB1 deactivation after 14 and 28 days and reduced microglial ramification by ABCB1, ABCC1 and combined ABCB1 and ABCC1 deactivation after 56 days. Endogenous neurogenesis, assessed by BrdU incorporation analysis, was not influenced by ABCB1, ABCC1 or combined ABCB1 and ABCC1 deactivation. Taken together, this study could not detect any exacerbation of neurological deficits or brain injury after long-term ABC transporter deactivation in this preclinical stroke model.
- Published
- 2019
- Full Text
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95. Intestinal Acid Sphingomyelinase Protects From Severe Pathogen-Driven Colitis
- Author
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Jana Meiners, Vittoria Palmieri, Robert Klopfleisch, Jana-Fabienne Ebel, Lukasz Japtok, Fabian Schumacher, Ayan Mohamud Yusuf, Katrin A. Becker, Julia Zöller, Matthias Hose, Burkhard Kleuser, Dirk M. Hermann, Richard N. Kolesnick, Jan Buer, Wiebke Hansen, and Astrid M. Westendorf
- Subjects
Citrobacter rodentium ,colitis ,acid sphingomyelinase ,amitriptyline ,Th1 ,Th17 ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Inflammatory diseases of the gastrointestinal tract are emerging as a global problem with increased evidence and prevalence in numerous countries. A dysregulated sphingolipid metabolism occurs in patients with ulcerative colitis and is discussed to contribute to its pathogenesis. In the present study, we determined the impact of acid sphingomyelinase (Asm), which catalyzes the hydrolysis of sphingomyelin to ceramide, on the course of Citrobacter (C.) rodentium-driven colitis. C. rodentium is an enteric pathogen and induces colonic inflammation very similar to the pathology in patients with ulcerative colitis. We found that mice with Asm deficiency or Asm inhibition were strongly susceptible to C. rodentium infection. These mice showed increased levels of C. rodentium in the feces and were prone to bacterial spreading to the systemic organs. In addition, mice lacking Asm activity showed an uncontrolled inflammatory Th1 and Th17 response, which was accompanied by a stronger colonic pathology compared to infected wild type mice. These findings identified Asm as an essential regulator of mucosal immunity to the enteric pathogen C. rodentium.
- Published
- 2019
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96. Acute and Post-acute Neuromodulation Induces Stroke Recovery by Promoting Survival Signaling, Neurogenesis, and Pyramidal Tract Plasticity
- Author
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Ahmet B. Caglayan, Mustafa C. Beker, Berrak Caglayan, Esra Yalcin, Aysun Caglayan, Burak Yulug, Lutfu Hanoglu, Selim Kutlu, Thorsten R. Doeppner, Dirk M. Hermann, and Ertugrul Kilic
- Subjects
neurodegeneration ,apoptosis ,tissue remodeling ,rTMS ,cerebral ischemia ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Repetitive transcranial magnetic stimulation (rTMS) has gained interest as a non-invasive treatment for stroke based on the data promoting its effects on functional recovery. However, the exact action mechanisms by which the rTMS exert beneficial effects in cellular and molecular aspect are largely unknown. To elucidate the effects of high- and low-frequency rTMS in the acute-ischemic brain, we examined how rTMS influences injury development, cerebral blood flow (CBF), DNA fragmentation, neuronal survival, pro- and anti-apoptotic protein activations after 30 and 90 min of focal cerebral ischemia. In addition, inflammation, angiogenesis, growth factors and axonal outgrowth related gene expressions, were analyzed. Furthermore, we have investigated the effects of rTMS on post-acute ischemic brain, particularly on spontaneous locomotor activity, perilesional tissue remodeling, axonal sprouting of corticobulbar tracts, glial scar formation and cell proliferation, in which rTMS was applied starting 3 days after the stroke onset for 28 days. In the high-frequency rTMS received animals reduced DNA fragmentation, infarct volume and improved CBF were observed, which were associated with increased Bcl-xL activity and reduced Bax, caspase-1, and caspase-3 activations. Moreover, increased angiogenesis, growth factors; and reduced inflammation and axonal sprouting related gene expressions were observed. These results correlated with reduced microglial activation, neuronal degeneration, glial scar formation and improved functional recovery, tissue remodeling, contralesional pyramidal tract plasticity and neurogenesis in the subacute rTMS treated animals. Overall, we propose that high-frequency rTMS in stroke patients can be used to promote functional recovery by inducing the endogenous repair and recovery mechanisms of the brain.
- Published
- 2019
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97. Upper respiratory tract disease and associated diagnostic tests of mycoplasmosis in Alabama populations of Gopher tortoises, Gopherus polyphemus.
- Author
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Jeffrey M Goessling, Craig Guyer, James C Godwin, Sharon M Hermann, Franzisca C Sandmeier, Lora L Smith, and Mary T Mendonça
- Subjects
Medicine ,Science - Abstract
Upper respiratory tract disease (URTD) in North American tortoises (Gopherus) has been the focus of numerous laboratory and field investigations, yet the prevalence and importance of this disease remains unclear across many tortoise populations. Furthermore, much research has been focused on understanding diagnostic biomarkers of two known agents of URTD, Mycoplasma agassizii and Mycoplasma testudineum, yet the reliability and importance of these diagnostic biomarkers across populations is unclear. Gopher Tortoises (Gopherus polyphemus) have experienced significant declines and are currently protected range wide. Geographically, Alabama represents an important connection for Gopher Tortoise populations between the core and periphery of this species' distribution. Herein, we systematically sampled 197 Gopher Tortoises for URTD across seven sites in south-central and south-eastern Alabama. Plasma samples were assayed for antibodies to M. agassizii and M. testudineum; nasal lavage samples were assayed for the presence of viable pathogens as well as pathogen DNA. Lastly, animals were scored for the presence of external symptoms and nasal scarring consistent with URTD. External symptoms of URTD were present in G. polyphemus in all sites sampled in Alabama. There was no relationship between active symptoms of URTD and Mycoplasma antibodies, however the presence of URTD nasal scarring was positively related to M. agassizii antibodies (P = 0.032). For a single site that was sampled in three sequential years, seroprevalence to M. agassizii significantly varied among years (P < 0.0001). Mycoplasma agassizii DNA was isolated from four of the seven sites using quantitative PCR, yet none of the samples were culture positive for either of the pathogens. An analysis of disease status and condition indicated that there was a significant, positive relationship between the severity of URTD symptoms and relative body mass (P < 0.05). This study highlights the need for continued monitoring of disease in wild populations. Specifically, focus must be placed on identifying other likely pathogens and relevant biomarkers that may be important drivers of URTD in North American tortoises. Special consideration should be given to environmental contexts that may render wild populations more susceptible to disease.
- Published
- 2019
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98. Opportunities and Limitations of Vascular Risk Factor Models in Studying Plasticity-Promoting and Restorative Ischemic Stroke Therapies
- Author
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Dirk M. Hermann, Thorsten R. Doeppner, and Aurel Popa-Wagner
- Subjects
Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Major efforts are currently made promoting neuronal plasticity and brain remodeling in the postacute stroke phase. Experimental studies evaluating new stroke therapies are mostly performed in rodents, which compared to humans exhibit a short lifespan. These studies widely employ young, otherwise healthy, rodents that lack the vascular risk factors and comorbidities of stroke patients. These risk factors compromise postischemic neurological recovery and brain plasticity and in several contexts reduce the brain responsiveness to recovery-inducing plasticity-promoting treatments. By examining risk factor models, which have hitherto been used for studying experimentally induced ischemic stroke, this review outlines the possibilities and limitations of risk factor models in the evaluation of plasticity-promoting and restorative stroke treatments.
- Published
- 2019
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99. Intracortical Administration of the Complement C3 Receptor Antagonist Trifluoroacetate Modulates Microglia Reaction after Brain Injury
- Author
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Roxana Surugiu, Bogdan Catalin, Danut Dumbrava, Andrei Gresita, Denisa Greta Olaru, Dirk M. Hermann, and Aurel Popa-Wagner
- Subjects
Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Worldwide, millions of individuals suffer an ischemic stroke each year, causing major disability, especially in the elderly, where stroke is the number one cause of disability. However, to date, no effective therapy exists that targets the functional recovery after stroke. After necrosis, neuroinflammation is a common feature of the acute stroke and a major obstacle to tissue restoration. In the lesioned area, the dying neurons release chemotactic signals, such as fractalkine/CX3CL1, which evoke “eat-me” signals that are recognized by microglia expressing complement C3a receptor (C3aR), resulting in phagocytosis of the dying but still viable neurons, known as secondary phagocytosis. Using a mouse model of stroke and two-photon microscopy, we aimed to attenuate poststroke phagocytosis of the dying but still viable neurons by using SB 290157, an antagonist of C3aR. We found that intracortical administration of SB 290157 reduced the number of inflammatory microglial cells expressing ED1 and Iba1 antigens at the lesion site. We could show, in vivo, that two days after a needle-induced cortical lesion there were less microglial cells present around the injury site, displaying less high-order branches and an increase in the lower order ones, suggesting an attenuated phagocytic phenotype in treated animals as compared with controls. We conclude that the C3aR antagonist, SB 290157, may be used in the future to limit the neuronal death by limiting secondary phagocytosis after stroke.
- Published
- 2019
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100. Precipitation with polyethylene glycol followed by washing and pelleting by ultracentrifugation enriches extracellular vesicles from tissue culture supernatants in small and large scales
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Anna-Kristin Ludwig, Kyra De Miroschedji, Thorsten R. Doeppner, Verena Börger, Johannes Ruesing, Vera Rebmann, Stephan Durst, Sören Jansen, Michel Bremer, Elmar Behrmann, Bernhard B. Singer, Holger Jastrow, Jan Dominik Kuhlmann, Fouzi El Magraoui, Helmut E. Meyer, Dirk M. Hermann, Bertram Opalka, Stefan Raunser, Matthias Epple, Peter A. Horn, and Bernd Giebel
- Subjects
Exosomes ,microvesicles ,extracellular vesicles ,CD63 ,PEG ,Cytology ,QH573-671 - Abstract
Extracellular vesicles (EVs) provide a complex means of intercellular signalling between cells at local and distant sites, both within and between different organs. According to their cell-type specific signatures, EVs can function as a novel class of biomarkers for a variety of diseases, and can be used as drug-delivery vehicles. Furthermore, EVs from certain cell types exert beneficial effects in regenerative medicine and for immune modulation. Several techniques are available to harvest EVs from various body fluids or cell culture supernatants. Classically, differential centrifugation, density gradient centrifugation, size-exclusion chromatography and immunocapturing-based methods are used to harvest EVs from EV-containing liquids. Owing to limitations in the scalability of any of these methods, we designed and optimised a polyethylene glycol (PEG)-based precipitation method to enrich EVs from cell culture supernatants. We demonstrate the reproducibility and scalability of this method and compared its efficacy with more classical EV-harvesting methods. We show that washing of the PEG pellet and the re-precipitation by ultracentrifugation remove a huge proportion of PEG co-precipitated molecules such as bovine serum albumine (BSA). However, supported by the results of the size exclusion chromatography, which revealed a higher purity in terms of particles per milligram protein of the obtained EV samples, PEG-prepared EV samples most likely still contain a certain percentage of other non-EV associated molecules. Since PEG-enriched EVs revealed the same therapeutic activity in an ischemic stroke model than corresponding cells, it is unlikely that such co-purified molecules negatively affect the functional properties of obtained EV samples. In summary, maybe not being the purification method of choice if molecular profiling of pure EV samples is intended, the optimised PEG protocol is a scalable and reproducible method, which can easily be adopted by laboratories equipped with an ultracentrifuge to enrich for functional active EVs.
- Published
- 2018
- Full Text
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