@article{PhamHelluyBraeuningeretal.2010,
  author    = {Pham, Mirko and Helluy, X. and Braeuninger, S. and Jakob, P. and Stoll, G. and Kleinschnitz, Christoph and Bendszus, M.},
  title     = {Outcome of experimental stroke in C57Bl/6 and Sv/129 mice assessed by multimodal ultra-high field MRI},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68115},
  year      = {2010},
  abstract  = {Transgenic mice bred on C57Bl/6 or Sv/129 genetic background are frequently used in stroke research. It is well established that variations in cerebrovascular anatomy and hemodynamics can influence stroke outcome in different inbred mouse lines. We compared stroke development in C57Bl/6 and Sv/129 mice in the widely used model of transient middle cerebral artery occlusion (tMCAO) by multimodal ultra-high field magnetic resonance imaging (MRI). C57Bl/6 and Sv/129 mice underwent 60 min of tMCAO and were analyzed by MRI 2 h and 24 h afterwards. Structural and functional images were registered to a standard anatomical template. Probability maps of infarction were rendered by automated segmentation from quantitative T2-relaxometric images. Whole-brain segmentation of infarction was accomplished manually on high-resolution T2-weighted (T2-w) RARE images. Cerebral perfusion (cerebral blood flow, CBF) was measured quantitatively by modified continuous arterial-spin-labeling (CASL) and apparent diffusion coefficients (ADC) by spin-echo diffusion-weighted imaging (DWI). Probabilities of cortical (95.1\% ± 3.1 vs. 92.1\% ± 2.5; p > 0.05) and subcortical (100\% vs. 100\%; p > 0.05) infarctions at 24 h were similar in both groups as was the whole-brain volumetric extent of cerebral infarction. In addition, CBF and ADC values did not differ between C57Bl/6 and Sv/129 mice at any time point or region of interest. The C57Bl/6 and Sv/129 genetic background is no major confounding factor of infarct size and cerebral perfusion in the tMCAO model.},
  subject      = {NMR-Tomographie},
  language  = {en}
}
@article{PhamHelluyKleinschnitzetal.2011,
  author    = {Pham, Mirko and Helluy, Xavier and Kleinschnitz, Christoph and Kraft, Peter and Bartsch, Andreas J. and Jakob, Peter and Nieswandt, Bernhard and Bendszus, Martin and Guido, Stoll},
  title     = {Sustained Reperfusion after Blockade of Glycoprotein-Receptor-Ib in Focal Cerebral Ischemia: An MRI Study at 17.6 Tesla},
  series = {PLoS ONE},
  volume    = {6},
  journal   = {PLoS ONE},
  number    = {4},
  doi       = {10.1371/journal.pone.0018386},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142608},
  pages     = {e18386},
  year      = {2011},
  abstract  = {Background: Inhibition of early platelet adhesion by blockade of glycoprotein-IB (GPIb) protects mice from ischemic stroke. To elucidate underlying mechanisms in-vivo, infarct development was followed by ultra-high field MRI at 17.6 Tesla. Methods: Cerebral infarction was induced by transient-middle-cerebral-artery-occlusion (tMCAO) for 1 hour in C57/BL6 control mice (N = 10) and mice treated with 100 mg Fab-fragments of the GPIb blocking antibody p0p/B 1 h after tMCAO (N = 10). To control for the effect of reperfusion, additional mice underwent permanent occlusion and received anti-GPIb treatment (N = 6; pMCAO) or remained without treatment (N = 3; pMCAO). MRI 2 h and 24 h after MCAO measured cerebral-blood-flow (CBF) by continuous arterial-spin labelling, the apparent-diffusion-coefficient (ADC), quantitative-T2 and T2-weighted imaging. All images were registered to a standard mouse brain MRI atlas and statistically analysed voxel-wise, and by cortico-subcortical ROI analysis. Results: Anti-GPIb treatment led to a relative increase of postischemic CBF vs. controls in the cortical territory of the MCA (2 h: 44.2 +/- 6.9 ml/100g/min versus 24 h: 60.5 +/- 8.4; p = 0.0012, F((1,18)) = 14.63) after tMCAO. Subcortical CBF 2 h after tMCAO was higher in anti-GPIb treated animals (45.3 +/- 5.9 vs. controls: 33.6 +/- 4.3; p = 0.04). In both regions, CBF findings were clearly related to a lower probability of infarction (Cortex/Subcortex of treated group: 35\%/65\% vs. controls: 95\%/100\%) and improved quantitative-T2 and ADC. After pMCAO, anti-GPIb treated mice developed similar infarcts preceded by severe irreversible hypoperfusion as controls after tMCAO indicating dependency of stroke protection on reperfusion. Conclusion: Blockade of platelet adhesion by anti-GPIb-Fab-fragments results in substantially improved CBF early during reperfusion. This finding was in exact spatial correspondence with the prevention of cerebral infarction and indicates in-vivo an increased patency of the microcirculation. Thus, progression of infarction during early ischemia and reperfusion can be mitigated by anti-platelet treatment.},
  language  = {en}
}
@article{KunzePhamRaslanetal.2012,
  author    = {Kunze, Ekkehard and Pham, Mirko and Raslan, Furat and Stetter, Christian and Lee, Jin-Yul and Solymosi, Laszlo and Ernestus, Ralf-Ingo and Hamilton Vince, Giles and Westermaier, Thomas},
  title     = {Value of Perfusion CT, Transcranial Doppler Sonography and Neurological Examination to detect delayed Vasospasm after aneurysmal Subarachnoid Hemorrhage [Research Article]},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-76241},
  year      = {2012},
  abstract  = {Background If detected in time, delayed cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) may be treated by balloon angioplasty or chemical vasospasmolysis in order to enhance cerebral blood flow (CBF) and protect the brain from ischemic damage. This study was conceived to compare the diagnostic accuracy of detailed neurological examination, Transcranial Doppler Sonography (TCD), and Perfusion-CT (PCT) to detect angiographic vasospasm. Methods The sensitivity, specificity, positive and negative predictive values of delayed ischemic neurological deterioration (DIND), pathological findings on PCT- maps, and accelerations of the mean flow velocity (MVF) were calculated. Results The accuracy of DIND to predict angiographic vasospasm was 0.88. An acceleration of MFV in TCD (>140 cm/s) had an accuracy of 0.64, positive PCT-findings of 0.69 with a higher sensitivity, and negative predictive value than TCD. Interpretation Neurological assessment at close intervals is the most sensitive and specific parameter for cerebral vasospasm. PCT has a higher accuracy, sensitivity and negative predictive value than TCD. If detailed neurological evaluation is possible, it should be the leading parameter in the management and treatment decisions. If patients are not amenable to detailed neurological examination, PCT at regular intervals is a helpful tool to diagnose secondary vasospasm after aneurysmal SAH.},
  subject      = {Medizin},
  language  = {en}
}
@article{ElhfnawyHeuschmannPhametal.2019,
  author    = {Elhfnawy, Ahmed Mohamed and Heuschmann, Peter U. and Pham, Mirko and Volkmann, Jens and Fluri, Felix},
  title     = {Stenosis length and degree interact with the risk of cerebrovascular events related to internal carotid artery stenosis},
  series = {Frontiers in Neurology},
  volume    = {10},
  journal   = {Frontiers in Neurology},
  number    = {317},
  issn      = {1664-2295},
  doi       = {10.3389/fneur.2019.00317},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196225},
  year      = {2019},
  abstract  = {Background and Purpose: Internal carotid artery stenosis (ICAS)≥70\% is a leading cause of ischemic cerebrovascular events (ICVEs). However, a considerable percentage of stroke survivors with symptomatic ICAS (sICAS) have <70\% stenosis with a vulnerable plaque. Whether the length of ICAS is associated with high risk of ICVEs is poorly investigated. Our main aim was to investigate the relation between the length of ICAS and the development of ICVEs. Methods: In a retrospective cross-sectional study, we identified 95 arteries with sICAS and another 64 with asymptomatic internal carotid artery stenosis (aICAS) among 121 patients with ICVEs. The degree and length of ICAS as well as plaque echolucency were assessed on ultrasound scans. Results: A statistically significant inverse correlation between the ultrasound-measured length and degree of ICAS was detected for sICAS≥70\% (Spearman correlation coefficient ρ = -0.57, p < 0.001, n = 51) but neither for sICAS<70\% (ρ = 0.15, p = 0.45, n = 27) nor for aICAS (ρ = 0.07, p = 0.64, n = 54). The median (IQR) length for sICAS<70\% and ≥70\% was 17 (15-20) and 15 (12-19) mm (p = 0.06), respectively, while that for sICAS<90\% and sICAS 90\% was 18 (15-21) and 13 (10-16) mm, respectively (p < 0.001). Among patients with ICAS <70\%, a cut-off length of ≥16 mm was found for sICAS rather than aICAS with a sensitivity and specificity of 74.1\% and 51.1\%, respectively. Irrespective of the stenotic degree, plaques of the sICAS compared to aICAS were significantly more often echolucent (43.2 vs. 24.6\%, p = 0.02). Conclusion: We found a statistically insignificant tendency for the ultrasound-measured length of sICAS<70\% to be longer than that of sICAS≥70\%. Moreover, the ultrasound-measured length of sICAS<90\% was significantly longer than that of sICAS 90\%. Among patients with sICAS≥70\%, the degree and length of stenosis were inversely correlated. Larger studies are needed before a clinical implication can be drawn from these results.},
  language  = {en}
}
@article{SchuhmannKraftBieberetal.2019,
  author    = {Schuhmann, Michael K. and Kraft, Peter and Bieber, Michael and Kollikowski, Alexander M. and Schulze, Harald and Nieswandt, Bernhard and Pham, Mirko and Stegner, David and Stoll, Guido},
  title     = {Targeting platelet GPVI plus rt-PA administration but not α2β1-mediated collagen binding protects against ischemic brain damage in mice},
  series = {International Journal of Molecular Science},
  volume    = {20},
  journal   = {International Journal of Molecular Science},
  number    = {8},
  issn      = {1422-0067},
  doi       = {10.3390/ijms20082019},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201700},
  year      = {2019},
  abstract  = {Platelet collagen interactions at sites of vascular injuries predominantly involve glycoprotein VI (GPVI) and the integrin α2β1. Both proteins are primarily expressed on platelets and megakaryocytes whereas GPVI expression is also shown on endothelial and integrin α2β1 expression on epithelial cells. We recently showed that depletion of GPVI improves stroke outcome without increasing the risk of cerebral hemorrhage. Genetic variants associated with higher platelet surface integrin α2 (ITGA2) receptor levels have frequently been found to correlate with an increased risk of ischemic stroke in patients. However until now, no preclinical stroke study has addressed whether platelet integrin α2β1 contributes to the pathophysiology of ischemia/reperfusion (I/R) injury. Focal cerebral ischemia was induced in C57BL/6 and Itga2\(^{-/-}\) mice by a 60 min transient middle cerebral artery occlusion (tMCAO). Additionally, wild-type animals were pretreated with anti-GPVI antibody (JAQ1) or Fab fragments of a function blocking antibody against integrin α2β1 (LEN/B). In anti-GPVI treated animals, intravenous (IV) recombinant tissue plasminogen activator (rt-PA) treatment was applied immediately prior to reperfusion. Stroke outcome, including infarct size and neurological scoring was determined on day 1 after tMCAO. We demonstrate that targeting the integrin α2β1 (pharmacologic; genetic) did neither reduce stroke size nor improve functional outcome on day 1 after tMCAO. In contrast, depletion of platelet GPVI prior to stroke was safe and effective, even when combined with rt-PA treatment. Our results underscore that GPVI, but not ITGA2, is a promising and safe target in the setting of ischemic stroke.},
  language  = {en}
}
@article{EssigKollikowskiPhametal.2020,
  author    = {Essig, Fabian and Kollikowski, Alexander M. and Pham, Mirko and Solymosi, L{\´a}szl{\´o} and Stoll, Guido and Haeusler, Karl Georg and Kraft, Peter and Schuhmann, Michael K.},
  title     = {Immunohistological analysis of neutrophils and neutrophil extracellular traps in human thrombemboli causing acute ischemic stroke},
  series = {International Journal of Molecular Sciences},
  volume    = {21},
  journal   = {International Journal of Molecular Sciences},
  number    = {19},
  issn      = {1422-0067},
  doi       = {10.3390/ijms21197387},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236192},
  year      = {2020},
  abstract  = {Ischemic stroke caused by thromboembolic occlusion of large cerebral arteries, such as the internal carotid (ICA) and/or the middle cerebral artery (MCA), is treated by mechanical thrombectomy (MT). MT allows salvage of the vessel-occluding thrombemboli, which most frequently originate from the left atrium or the left ventricle of the heart or from sites of plaque rupture within large arteries above the heart. Clot composition may influence the efficacy of (intravenous) thrombolysis and MT, respectively. We analyzed 37 human thrombemboli obtained from acute ischemic stroke patients during MT with special emphasis on histological staining of neutrophils and neutrophil extracellular traps (NETs). We found neutrophils as the main cellular component of cerebral thrombemboli but encountered considerable morphological heterogeneity. Neutrophils accumulated in the border region of fibrin-rich structures indicating possible interaction of neutrophils with distinct structural thrombembolus components. Web-like NETs were found in 35 of 37 thrombemboli in varying amounts. NETs were almost exclusively found within fibrin-rich areas. Importantly, stroke etiology, age and present oral anticoagulation was associated with morphological patterns and the amount of neutrophils. Correlation of histological data and imaging data revealed that relative Hounsfield units of cerebral thrombemboli positively correlated with the amount of red blood cells. In summary, our results demonstrate that neutrophils and NETs are substantial constituents of cerebral thrombemboli and contribute to their structural complexity.},
  language  = {en}
}
@article{NguemeniHomolaNakchbandietal.2020,
  author    = {Nguemeni, Carine and Homola, Gy{\"o}rgy A. and Nakchbandi, Luis and Pham, Mirko and Volkmann, Jens and Zeller, Daniel},
  title     = {A Single Session of Anodal Cerebellar Transcranial Direct Current Stimulation Does Not Induce Facilitation of Locomotor Consolidation in Patients With Multiple Sclerosis},
  series = {Frontiers in Human Neuroscience},
  volume    = {14},
  journal   = {Frontiers in Human Neuroscience},
  issn      = {1662-5161},
  doi       = {10.3389/fnhum.2020.588671},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-215291},
  year      = {2020},
  abstract  = {Background: Multiple sclerosis (MS) may cause variable functional impairment. The discrepancy between functional impairment and brain imaging findings in patients with MS (PwMS) might be attributed to differential adaptive and consolidation capacities. Modulating those abilities could contribute to a favorable clinical course of the disease. Objectives: We examined the effect of cerebellar transcranial direct current stimulation (c-tDCS) on locomotor adaptation and consolidation in PwMS using a split-belt treadmill (SBT) paradigm. Methods: 40 PwMS and 30 matched healthy controls performed a locomotor adaptation task on a SBT. First, we assessed locomotor adaptation in PwMS. In a second investigation, this training was followed by cerebellar anodal tDCS applied immediately after the task ipsilateral to the fast leg (T0). The SBT paradigm was repeated 24 h (T1) and 78 h (T2) post-stimulation to evaluate consolidation. Results: The gait dynamics and adaptation on the SBT were comparable between PwMS and controls. We found no effects of offline cerebellar anodal tDCS on locomotor adaptation and consolidation. Participants who received the active stimulation showed the same retention index than sham-stimulated subjects at T1 (p = 0.33) and T2 (p = 0.46). Conclusion: Locomotor adaptation is preserved in people with mild-to-moderate MS. However, cerebellar anodal tDCS applied immediately post-training does not further enhance this ability. Future studies should define the neurobiological substrates of maintained plasticity in PwMS and how these substrates can be manipulated to improve compensation. Systematic assessments of methodological variables for cerebellar tDCS are urgently needed to increase the consistency and replicability of the results across experiments in various settings.},
  language  = {en}
}
@article{KollikowskiSchuhmannNieswandtetal.2020,
  author    = {Kollikowski, Alexander M. and Schuhmann, Michael K. and Nieswandt, Bernhard and M{\"u}llges, Wolfgang and Stoll, Guido and Pham, Mirko},
  title     = {Local Leukocyte Invasion during Hyperacute Human Ischemic Stroke},
  series = {Annals of Neurology},
  volume    = {87},
  journal   = {Annals of Neurology},
  number    = {3},
  doi       = {10.1002/ana.25665},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212168},
  pages     = {466-479},
  year      = {2020},
  abstract  = {Objective Bridging the gap between experimental stroke and patients by ischemic blood probing during the hyperacute stage of vascular occlusion is crucial to assess the role of inflammation in human stroke and for the development of adjunct treatments beyond recanalization. Methods We prospectively observed 151 consecutive ischemic stroke patients with embolic large vessel occlusion of the anterior circulation who underwent mechanical thrombectomy. In all these patients, we attempted microcatheter aspiration of 3 different arterial blood samples: (1) within the core of the occluded vascular compartment and controlled by (2) carotid and (3) femoral samples obtained under physiological flow conditions. Subsequent laboratory analyses comprised leukocyte counting and differentiation, platelet counting, and the quantification of 13 proinflammatory human chemokines/cytokines. Results Forty patients meeting all clinical, imaging, interventional, and laboratory inclusion criteria could be analyzed, showing that the total number of leukocytes significantly increased under the occlusion condition. This increase was predominantly driven by neutrophils. Significant increases were also apparent for lymphocytes and monocytes, accompanied by locally elevated plasma levels of the T-cell chemoattractant CXCL-11. Finally, we found evidence that short-term clinical outcome (National Institute of Health Stroke Scale at 72 hours) was negatively associated with neutrophil accumulation. Interpretation We provide the first direct human evidence that neutrophils, lymphocytes, and monocytes, accompanied by specific chemokine upregulation, accumulate in the ischemic vasculature during hyperacute stroke and may affect outcome. These findings strongly support experimental evidence that immune cells contribute to acute ischemic brain damage and indicate that ischemic inflammation initiates already during vascular occlusion. Ann Neurol 2020;87:466-479},
  language  = {en}
}
@article{EssigBabilonVollmuthetal.2021,
  author    = {Essig, Fabian and Babilon, Lilith and Vollmuth, Christoph and Kollikowski, Alexander M. and Pham, Mirko and Solymosi, L{\´a}szl{\´o} and Haeusler, Karl Georg and Kraft, Peter and Stoll, Guido and Schuhmann, Michael K.},
  title     = {High mobility group box 1 protein in cerebral thromboemboli},
  series = {International Journal of Molecular Sciences},
  volume    = {22},
  journal   = {International Journal of Molecular Sciences},
  number    = {20},
  issn      = {1422-0067},
  doi       = {10.3390/ijms222011276},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265568},
  year      = {2021},
  abstract  = {High-mobility group box 1 protein (HMGB1) is a damage-associated molecular pattern (DAMP) involved in neutrophil extracellular trap (NET) formation and thrombosis. NETs are regularly found in cerebral thromboemboli. We here analyzed associated HMGB1 expression in human thromboemboli retrieved via mechanical thrombectomy from 37 stroke patients with large vessel occlusion. HMGB1 was detected in all thromboemboli, accounting for 1.7\% (IQR 0.6-6.2\%) of the total thromboemboli area and was found to be colocalized with neutrophils and NETs and in spatial proximity to platelets. Correlation analysis revealed that the detection of HMGB1 was strongly related to the number of neutrophils (r = 0.58, p = 0.0002) and platelets (r = 0.51, p = 0.001). Our results demonstrate that HMGB1 is a substantial constituent of thromboemboli causing large vessel occlusion stroke.},
  language  = {en}
}
@article{BieberFoersterHaefelietal.2021,
  author    = {Bieber, Michael and Foerster, Kathrin I. and Haefeli, Walter E. and Pham, Mirko and Schuhmann, Michael K. and Kraft, Peter},
  title     = {Treatment with edoxaban attenuates acute stroke severity in mice by reducing blood-brain barrier damage and inflammation},
  series = {International Journal of Molecular Sciences},
  volume    = {22},
  journal   = {International Journal of Molecular Sciences},
  number    = {18},
  issn      = {1422-0067},
  doi       = {10.3390/ijms22189893},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-284481},
  year      = {2021},
  abstract  = {Patients with atrial fibrillation and previous ischemic stroke (IS) are at increased risk of cerebrovascular events despite anticoagulation. In these patients, treatment with non-vitamin K oral anticoagulants (NOAC) such as edoxaban reduced the probability and severity of further IS without increasing the risk of major bleeding. However, the detailed protective mechanism of edoxaban has not yet been investigated in a model of ischemia/reperfusion injury. Therefore, in the current study we aimed to assess in a clinically relevant setting whether treatment with edoxaban attenuates stroke severity, and whether edoxaban has an impact on the local cerebral inflammatory response and blood-brain barrier (BBB) function after experimental IS in mice. Focal cerebral ischemia was induced by transient middle cerebral artery occlusion in male mice receiving edoxaban, phenprocoumon or vehicle. Infarct volumes, functional outcome and the occurrence of intracerebral hemorrhage were assessed. BBB damage and the extent of local inflammatory response were determined. Treatment with edoxaban significantly reduced infarct volumes and improved neurological outcome and BBB function on day 1 and attenuated brain tissue inflammation. In summary, our study provides evidence that edoxaban might exert its protective effect in human IS by modulating different key steps of IS pathophysiology, but further studies are warranted.},
  language  = {en}
}