@article{BachmannEhlertBeckeretal.2020, author = {Bachmann, Julia and Ehlert, Elias and Becker, Matthias and Otto, Christoph and Radeloff, Katrin and Blunk, Torsten and Bauer-Kreisel, Petra}, title = {Ischemia-like stress conditions stimulate trophic activities of adipose-derived stromal/stem cells}, series = {Cells}, volume = {9}, journal = {Cells}, number = {9}, issn = {2073-4409}, doi = {10.3390/cells9091935}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-211233}, year = {2020}, abstract = {Adipose-derived stromal/stem cells (ASCs) have been shown to exert regenerative functions, which are mainly attributed to the secretion of trophic factors. Upon transplantation, ASCs are facing an ischemic environment characterized by oxygen and nutrient deprivation. However, current knowledge on the secretion capacity of ASCs under such conditions is limited. Thus, the present study focused on the secretory function of ASCs under glucose and oxygen deprivation as major components of ischemia. After exposure to glucose/oxygen deprivation, ASCs maintained distinct viability, but the metabolic activity was greatly reduced by glucose limitation. ASCs were able to secrete a broad panel of factors under glucose/oxygen deprivation as revealed by a cytokine antibody array. Quantification of selected factors by ELISA demonstrated that glucose deprivation in combination with hypoxia led to markedly higher secretion levels of the angiogenic and anti-apoptotic factors IL-6, VEGF, and stanniocalcin-1 as compared to the hypoxic condition alone. A conditioned medium of glucose/oxygen-deprived ASCs promoted the viability and tube formation of endothelial cells, and the proliferation and migration of fibroblasts. These findings indicate that ASCs are stimulated by ischemia-like stress conditions to secrete trophic factors and would be able to exert their beneficial function in an ischemic environment.}, language = {en} } @article{EhlingGoebBittneretal.2013, author = {Ehling, Petra and G{\"o}b, Eva and Bittner, Stefan and Budde, Thomas and Ludwig, Andreas and Kleinschnitz, Christoph and Meuth, Sven G.}, title = {Ischemia-induced cell depolarization: does the hyperpolarization-activated cation channel HCN2 affect the outcome after stroke in mice?}, series = {Experimental \& Translational Stroke Medicine}, volume = {5}, journal = {Experimental \& Translational Stroke Medicine}, number = {16}, doi = {10.1186/2040-7378-5-16}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131887}, year = {2013}, abstract = {Background Brain ischemia is known to include neuronal cell death and persisting neurological deficits. A lack of oxygen and glucose are considered to be key mediators of ischemic neurodegeneration while the exact mechanisms are yet unclear. In former studies the expression of two different two-pore domain potassium \((K_{2P})\) channels (TASK1, TREK1) were shown to ameliorate neuronal damage due to cerebral ischemia. In neurons, TASK channels carrying hyperpolarizing \(K^+\) leak currents, and the pacemaker channel HCN2, carrying depolarizing \(I_h\), stabilize the membrane potential by a mutual functional interaction. It is assumed that this ionic interplay between TASK and HCN2 channels enhances the resistance of neurons to insults accompanied by extracellular pH shifts. Methods In C57Bl/6 (wildtype, WT), \(hcn2^{+/+}\) and \(hcn2^{-/-}\) mice we used an in vivo model of cerebral ischemia (transient middle cerebral artery occlusion (tMCAO)) to depict a functional impact of HCN2 in stroke formation. Subsequent analyses comprise behavioural tests and hcn2 gene expression assays. Results After 60 min of tMCAO induction in WT mice, we collected tissue samples at 6, 12, and 24 h after reperfusion. In the infarcted neocortex, hcn2 expression analyses revealed a nominal peak of hcn2 expression 6 h after reperfusion with a tendency towards lower expression levels with longer reperfusion times. Hcn2 gene expression levels in infarcted basal ganglia did not change after 6 h and 12 h. Only at 24 h after reperfusion, hcn2 expression significantly decreases by ~55\%. However, 30 min of tMCAO in hcn2-/- as well as hcn2+/+ littermates induced similar infarct volumes. Behavioural tests for global neurological function (Bederson score) and motor function/coordination (grip test) were performed at day 1 after surgery. Again, we found no differences between the groups. Conclusions Here, we hypothesized that the absence of HCN2, an important functional counter player of TASK channels, affects neuronal survival during stroke-induced tissue damage. However, together with a former study on TASK3 these results implicate that both TASK3 and HCN2 which were supposed to be neuroprotective due to their pH-dependency, do not influence ischemic neurodegeneration during stroke in the tMCAO model.}, language = {en} } @article{GergsJahnSchulzetal.2022, author = {Gergs, Ulrich and Jahn, Tina and Schulz, Nico and Großmann, Claudia and Rueckschloss, Uwe and Demus, Uta and Buchwalow, Igor B. and Neumann, Joachim}, title = {Protein phosphatase 2A improves cardiac functional response to ischemia and sepsis}, series = {International Journal of Molecular Sciences}, volume = {23}, journal = {International Journal of Molecular Sciences}, number = {9}, issn = {1422-0067}, doi = {10.3390/ijms23094688}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-284035}, year = {2022}, abstract = {Reversible protein phosphorylation is a posttranslational modification of regulatory proteins involved in cardiac signaling pathways. Here, we focus on the role of protein phosphatase 2A (PP2A) for cardiac gene expression and stress response using a transgenic mouse model with cardiac myocyte-specific overexpression of the catalytic subunit of PP2A (PP2A-TG). Gene and protein expression were assessed under basal conditions by gene chip analysis and Western blotting. Some cardiac genes related to the cell metabolism and to protein phosphorylation such as kinases and phosphatases were altered in PP2A-TG compared to wild type mice (WT). As cardiac stressors, a lipopolysaccharide (LPS)-induced sepsis in vivo and a global cardiac ischemia in vitro (stop-flow isolated perfused heart model) were examined. Whereas the basal cardiac function was reduced in PP2A-TG as studied by echocardiography or as studied in the isolated work-performing heart, the acute LPS- or ischemia-induced cardiac dysfunction deteriorated less in PP2A-TG compared to WT. From the data, we conclude that increased PP2A activity may influence the acute stress tolerance of cardiac myocytes.}, language = {en} } @article{MegasSimonsKimetal.2021, author = {Megas, Ioannis-Fivos and Simons, David and Kim, Bong-Sung and Stoppe, Christian and Piatkowski, Andrzej and Fikatas, Panagiotis and Fuchs, Paul Christian and Bastiaanse, Jacqueline and Pallua, Norbert and Bernhagen, J{\"u}rgen and Grieb, Gerrit}, title = {Macrophage migration inhibitory factor — an innovative indicator for free flap ischemia after microsurgical reconstruction}, series = {Healthcare}, volume = {9}, journal = {Healthcare}, number = {6}, issn = {2227-9032}, doi = {10.3390/healthcare9060616}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239632}, year = {2021}, abstract = {(1) Background: Nowadays, the use of microsurgical free flaps is a standard operative procedure in reconstructive surgery. Still, thrombosis of the microanastomosis is one of the most fatal postoperative complications. Clinical evaluation, different technical devices and laboratory markers are used to monitor critical flap perfusion. Macrophage migration inhibitory factor (MIF), a structurally unique cytokine with chemokine-like characteristics, could play a role in predicting vascular problems and the failure of flap perfusion. (2) Methods: In this prospective observational study, 26 subjects that underwent microsurgical reconstruction were observed. Besides clinical data, the number of blood leukocytes, CRP and MIF were monitored. (3) Results: Blood levels of MIF, C-reactive protein (CRP) and leukocytes increased directly after surgery. Subjects that needed surgical revision due to thrombosis of the microanastomosis showed significantly higher blood levels of MIF than subjects without revision. (4) Conclusion: We conclude that MIF is a potential and innovative indicator for thrombosis of the microanastomosis after free flap surgery. Since it is easy to obtain diagnostically, MIF could be an additional tool to monitor flap perfusion besides clinical and technical assessments.}, language = {en} } @article{NeuhausGaiserMahringeretal.2014, author = {Neuhaus, Winfried and Gaiser, Fabian and Mahringer, Anne and Franz, Jonas and Riethm{\"u}ller, Christoph and F{\"o}rster, Carola}, title = {The pivotal role of astrocytes in an in vitro stroke model of the blood-brain barrier}, series = {Frontiers in Cellular Neuroscience}, volume = {8}, journal = {Frontiers in Cellular Neuroscience}, issn = {1662-5102}, doi = {10.3389/fncel.2014.00352}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-118297}, pages = {352}, year = {2014}, abstract = {Stabilization of the blood-brain barrier during and after stroke can lead to less adverse outcome. For elucidation of underlying mechanisms and development of novel therapeutic strategies validated in vitro disease models of the blood-brain barrier could be very helpful. To mimic in vitro stroke conditions we have established a blood-brain barrier in vitro model based on mouse cell line cerebEND and applied oxygen/glucose deprivation (OGD). The role of astrocytes in this disease model was investigated by using cell line C6. Transwell studies pointed out that addition of astrocytes during OGD increased the barrier damage significantly in comparison to the endothelial monoculture shown by changes of transendothelial electrical resistance as well as fluorescein permeability data. Analysis on mRNA and protein levels by qPCR, western blotting and immunofluorescence microscopy of tight junction molecules claudin-3,-5,-12, occludin and ZO-1 revealed that their regulation and localisation is associated with the functional barrier breakdown. Furthermore, soluble factors of astrocytes, OGD and their combination were able to induce changes of functionality and expression of ABC-transporters Abcb1a (P-gp), Abcg2 (bcrp), and Abcc4 (mrp4). Moreover, the expression of proteases (matrixmetalloproteinases MMP-2, MMP-3, MMP-9, and t-PA) as well as of their endogenous inhibitors (TIMP-1, TIMP-3, PAI-1) was altered by astrocyte factors and OGD which resulted in significant changes of total MMP and t-PA activity. Morphological rearrangements induced by OGD and treatment with astrocyte factors were confirmed at a nanometer scale using atomic force microscopy. In conclusion, astrocytes play a major role in blood-brain barrier breakdown during OGD in vitro.}, language = {en} } @article{PreisingSchneiderBucheretal.2015, author = {Preising, Christina and Schneider, Reinhard and Bucher, Michael and Gekle, Michael and Sauvant, Christoph}, title = {Regulation of expression of renal organic anion transporters OAT1 and OAT3 in a model of ischemia/reperfusion injury}, series = {Cellular Physiology and Biochemistry}, volume = {37}, journal = {Cellular Physiology and Biochemistry}, number = {1}, doi = {10.1159/000430328}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144504}, year = {2015}, abstract = {Background: Recently, we gained evidence that impairment of rOat1 and rOat3 expression induced by ischemic acute kidney injury (AKI) is mediated by COX metabolites and this suppression might be critically involved in renal damage. Methods: (i) Basolateral organic anion uptake into proximal tubular cells after model ischemia and reperfusion (I/R) was investigated by fluorescein uptake. The putative promoter sequences from hOAT1 (SLC22A6) and hOAT3 (SCL22A8) were cloned into a reporter plasmid, transfected into HEK cells and (ii) transcriptional activity was determined after model ischemia and reperfusion as a SEAP reporter gen assay. Inhibitors or antagonists were applied with the beginning of reperfusion. Results: By using inhibitors of PKA (H89) and PLC (U73122), antagonists of E prostanoid receptor type 2 (AH6809) and type 4 (L161,982), we gained evidence that I/R induced down regulation of organic anion transport is mediated by COX1 metabolites via E prostanoid receptor type 4. The latter signaling was confirmed by application of butaprost (EP2 agonist) or TCS2510 (EP4 agonist) to control cells. In brief, the latter signaling was verified for the transcriptional activity in the reporter gen assay established. Therein, selective inhibitors for COX1 (SC58125) and COX2 (SC560) were also applied. Conclusion: Our data show (a) that COX1 metabolites are involved in the regulation of renal organic anion transport(ers) after I/R via the EP4 receptor and (b) that this is due to transcriptional regulation of the respective transporters. As the promoter sequences cloned were of human origin and expressed in a human renal epithelial cell line we (c) hypothesize that the regulatory mechanisms described after I/R is meaningful for humans as well.}, language = {en} } @article{ReschkeSalvadorSchlegeletal.2022, author = {Reschke, Moritz and Salvador, Ellaine and Schlegel, Nicolas and Burek, Malgorzata and Karnati, Srikanth and Wunder, Christian and F{\"o}rster, Carola Y.}, title = {Isosteviol sodium (STVNA) reduces pro-inflammatory cytokine IL-6 and GM-CSF in an in vitro murine stroke model of the blood-brain barrier (BBB)}, series = {Pharmaceutics}, volume = {14}, journal = {Pharmaceutics}, number = {9}, issn = {1999-4923}, doi = {10.3390/pharmaceutics14091753}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286275}, year = {2022}, abstract = {Early treatment with glucocorticoids could help reduce both cytotoxic and vasogenic edema, leading to improved clinical outcome after stroke. In our previous study, isosteviol sodium (STVNA) demonstrated neuroprotective effects in an in vitro stroke model, which utilizes oxygen-glucose deprivation (OGD). Herein, we tested the hypothesis that STVNA can activate glucocorticoid receptor (GR) transcriptional activity in brain microvascular endothelial cells (BMECs) as previously published for T cells. STVNA exhibited no effects on transcriptional activation of the glucocorticoid receptor, contrary to previous reports in Jurkat cells. However, similar to dexamethasone, STVNA inhibited inflammatory marker IL-6 as well as granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion. Based on these results, STVNA proves to be beneficial as a possible prevention and treatment modality for brain ischemia-reperfusion injury-induced blood-brain barrier (BBB) dysfunction.}, language = {en} } @article{SchwitterWackerWilkeetal.2012, author = {Schwitter, Juerg and Wacker, Christian M. and Wilke, Norbert and Al-Saadi, Nidal and Sauer, Ekkehart and Huettle, Kalman and Sch{\"o}nberg, Stefan O. and Debl, Kurt and Strohm, Oliver and Ahlstrom, Hakan and Dill, Thorsten and Hoebel, Nadja and Simor, Tamas}, title = {Superior diagnostic performance of perfusion-cardiovascular magnetic resonance versus SPECT to detect coronary artery disease: The secondary endpoints of the multicenter multivendor MR-IMPACT II (Magnetic Resonance Imaging for Myocardial Perfusion Assessment in Coronary Artery Disease Trial)}, series = {Journal of Cardiovascular Magnetic Resonance}, volume = {14}, journal = {Journal of Cardiovascular Magnetic Resonance}, number = {61}, organization = {MR-IMPACT investigators}, doi = {10.1186/1532-429X-14-61}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134256}, year = {2012}, abstract = {Background: Perfusion-cardiovascular magnetic resonance (CMR) is generally accepted as an alternative to SPECT to assess myocardial ischemia non-invasively. However its performance vs gated-SPECT and in sub-populations is not fully established. The goal was to compare in a multicenter setting the diagnostic performance of perfusion-CMR and gated-SPECT for the detection of CAD in various populations using conventional x-ray coronary angiography (CXA) as the standard of reference. Methods: In 33 centers (in US and Europe) 533 patients, eligible for CXA or SPECT, were enrolled in this multivendor trial. SPECT and CXA were performed within 4 weeks before or after CMR in all patients. Prevalence of CAD in the sample was 49\% and 515 patients received MR contrast medium. Drop-out rates for CMR and SPECT were 5.6\% and 3.7\%, respectively (ns). The study was powered for the primary endpoint of non-inferiority of CMR vs SPECT for both, sensitivity and specificity for the detection of CAD (using a single-threshold reading), the results for the primary endpoint were reported elsewhere. In this article secondary endpoints are presented, i.e. the diagnostic performance of CMR versus SPECT in subpopulations such as multi-vessel disease (MVD), in men, in women, and in patients without prior myocardial infarction (MI). For diagnostic performance assessment the area under the receiver-operator-characteristics-curve (AUC) was calculated. Readers were blinded versus clinical data, CXA, and imaging results. Results: The diagnostic performance (= area under ROC = AUC) of CMR was superior to SPECT (p = 0.0004, n = 425) and to gated-SPECT (p = 0.018, n = 253). CMR performed better than SPECT in MVD (p = 0.003 vs all SPECT, p = 0.04 vs gated-SPECT), in men (p = 0.004, n = 313) and in women (p = 0.03, n = 112) as well as in the non-infarct patients (p = 0.005, n = 186 in 1-3 vessel disease and p = 0.015, n = 140 in MVD). Conclusion: In this large multicenter, multivendor study the diagnostic performance of perfusion-CMR to detect CAD was superior to perfusion SPECT in the entire population and in sub-groups. Perfusion-CMR can be recommended as an alternative for SPECT imaging.}, language = {en} } @article{VollmerSaraviBreitenbuecheretal.2023, author = {Vollmer, Andreas and Saravi, Babak and Breitenbuecher, Niko and Mueller-Richter, Urs and Straub, Anton and Šimić, Luka and K{\"u}bler, Alexander and Vollmer, Michael and Gubik, Sebastian and Volland, Julian and Hartmann, Stefan and Brands, Roman C.}, title = {Realizing in-house algorithm-driven free fibula flap set up within 24 hours}, series = {Frontiers in Surgery}, volume = {10}, journal = {Frontiers in Surgery}, doi = {10.3389/fsurg.2023.1321217}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-353945}, year = {2023}, abstract = {Objective: This study aims to critically evaluate the effectiveness and accuracy of a time safing and cost-efficient open-source algorithm for in-house planning of mandibular reconstructions using the free osteocutaneous fibula graft. The evaluation focuses on quantifying anatomical accuracy and assessing the impact on ischemia time. Methods: A pilot study was conducted, including patients who underwent in-house planned computer-aided design and manufacturing (CAD/CAM) of free fibula flaps between 2021 and 2023. Out of all patient cases, we included all with postoperative 3D imaging in the study. The study utilized open-source software tools for the planning step, and three-dimensional (3D) printing techniques. The Hausdorff distance and Dice coefficient metrics were used to evaluate the accuracy of the planning procedure. Results: The study assessed eight patients (five males and three females, mean age 61.75 ± 3.69 years) with different diagnoses such as osteoradionecrosis and oral squamous cell carcinoma. The average ischemia time was 68.38 ± 27.95 min. For the evaluation of preoperative planning vs. the postoperative outcome, the mean Hausdorff Distance was 1.22 ± 0.40. The Dice Coefficients yielded a mean of 0.77 ± 0.07, suggesting a satisfactory concordance between the planned and postoperative states. Dice Coefficient and Hausdorff Distance revealed significant correlations with ischemia time (Spearman's rho = -0.810, p = 0.015 and Spearman's rho = 0.762, p = 0.028, respectively). Linear regression models adjusting for disease type further substantiated these findings. Conclusions: The in-house planning algorithm not only achieved high anatomical accuracy, as reflected by the Dice Coefficients and Hausdorff Distance metrics, but this accuracy also exhibited a significant correlation with reduced ischemia time. This underlines the critical role of meticulous planning in surgical outcomes. Additionally, the algorithm's open-source nature renders it cost-efficient, easy to learn, and broadly applicable, offering promising avenues for enhancing both healthcare affordability and accessibility.}, language = {en} }