@phdthesis{ZimmermannneePapp2024,
  author    = {Zimmermann [n{\´e}e Papp], Lena},
  title     = {Platelets as modulators of blood-brain barrier disruption and inflammation in the pathophysiology of ischemic stroke},
  doi       = {10.25972/OPUS-30285},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-302850},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2024},
  abstract  = {Ischemia-reperfusion injury (I/R injury) is a common complication in ischemic stroke (IS) treatment, which is characterized by a paradoxical perpetuation of tissue damage despite the successful re-establishment of vascular perfusion. This phenomenon is known to be facilitated by the detrimental interplay of platelets and inflammatory cells at the vascular interface. However, the spatio-temporal and molecular mechanisms underlying these cellular interactions and their contribution to infarct progression are still incompletely understood. Therefore, this study intended to clarify the temporal mechanisms of infarct growth after cerebral vessel recanalization. The data presented here could show that infarct progression is driven by early blood-brain-barrier perturbation and is independent of secondary thrombus formation. Since previous studies unravelled the secretion of platelet granules as a molecular mechanism of how platelets contribute to I/R injury, special emphasis was placed on the role of platelet granule secretion in the process of barrier dysfunction. By combining an in vitro approach with a murine IS model, it could be shown that platelet α-granules exerted endothelial-damaging properties, whereas their absence (NBEAL2-deficiency) translated into improved microvascular integrity. Hence, targeting platelet α-granules might serve as a novel treatment option to reduce vascular integrity loss and diminish infarct growth despite recanalization. Recent evidence revealed that pathomechanisms underlying I/R injury are already instrumental during large vessel occlusion. This indicates that penumbral tissue loss under occlusion and I/R injury during reperfusion share an intertwined relationship. In accordance with this notion, human observational data disclosed the presence of a neutrophil dominated immune response and local platelet activation and secretion, by the detection of the main components of platelet α-granules, within the secluded vasculature of IS patients. These initial observations of immune cells and platelets could be further expanded within this thesis by flow cytometric analysis of local ischemic blood samples. Phenotyping of immune cells disclosed a yet unknown shift in the lymphocyte population towards CD4+ T cells and additionally corroborated the concept of an immediate intravascular immune response that is dominated by granulocytes. Furthermore, this thesis provides first-time evidence for the increased appearance of platelet-leukocyte-aggregates within the secluded human vasculature. Thus, interfering with immune cells and/or platelets already under occlusion might serve as a potential strategy to diminish infarct expansion and ameliorate clinical outcome after IS.},
  subject      = {Schlaganfall},
  language  = {en}
}
@phdthesis{Wilhelm2018,
  author    = {Wilhelm, Christian},
  title     = {Die Rolle von Chronophin bei Schlaganfall-induziertem Funktionsverlust der Blut-Hirn-Schranke},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-163877},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Der isch{\"a}mische Schlaganfall ist mit einer j{\"a}hrlichen Inzidenz von 200/100 000 Einwohnern die h{\"a}ufigste Gef{\"a}ßerkrankung in Deutschland. Atherothrombose, arterielle Hypertonie und Embolien unterschiedlichen Ursprungs sind die wesentlichen Ursachen des isch{\"a}mischen Schlaganfalls. Die neurologischen Defizite nach einem Schlaganfall resultieren aus einem gest{\"o}rten zerebralen Blutfluss und somit einer insuffizienten Sauerstoffversorgung. Zus{\"a}tzlich ist die {\"O}dembildung, welche von einer gesteigerten Permeabilit{\"a}t der Blut-Hirn-Schranke verursacht wird, am neuronalen Zelltod beteiligt. Chronophin ist eine Aktinzytoskelett-regulierende Serin-Phosphatase. In einem isch{\"a}mischen Schlaganfall-Modell konnte im Rahmen dieser Arbeit gezeigt werden, dass der globale Verlust von Chronophin zu einer vermehrten {\"O}dembildung und einem aggravierten neurologischen Zustand der M{\"a}use im Vergleich zu wildtypischen Kontrollen f{\"u}hrte. Hirnlysate von wildtypischen M{\"a}usen zeigten verringerte Chronophin-Level in der vom Schlaganfall betroffenen Hemisph{\"a}re. Jedoch konnten initiale immunhistochemische und zellbiologische Untersuchungen weder Chronophin-abh{\"a}ngige Ver{\"a}nderungen der Blut-Hirn-Schranke feststellen noch einen zerebralen Zelltyp identifizieren, der f{\"u}r den sch{\"u}tzenden Effekt von Chronophin verantwortlich ist. Diese Ergebnisse weisen auf einen komplexen, vielzelligen Mechanismus hin, dem die sch{\"u}tzende Rolle von Chronophin im isch{\"a}mischen Schlaganfall unterliegt. Die Entschl{\"u}sselung dieses Mechanismus ist Aufgabe k{\"u}nftiger Untersuchungen.},
  subject      = {Schlaganfall},
  language  = {de}
}
@phdthesis{Thielmann2014,
  author    = {Thielmann, Ina},
  title     = {Function and regulation of phospholipase D in blood platelets: in vitro and in vivo studies in mice},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-99179},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {Summary Platelet activation and aggregation are crucial for primary hemostasis but can also result in occlusive thrombus formation. Agonist induced platelet activation involves different signaling pathways leading to the activation of phospholipases (PL) which produce second messengers. While the role of PLCs in platelet activation is well established, less is known about the relevance of PLDs. In the current study, the function and regulation of PLD in platelets was investigated using genetic and pharmacological approaches. In the first part of this thesis, adhesion, activation and aggregation of platelets from mice lacking PLD2 or both PLD1 and PLD2 were analyzed in vitro and in vivo. While the absence of PLD2 resulted in slightly reduced PLD activity in platelets, it had no detectable effect on the platelet function in vitro and in vivo. However, the combined deficiency of both PLD isoforms resulted in defective alpha-granule release and protection in a model of ferric chloride induced arteriolar thrombosis, effects that were not observed in mice lacking only one PLD isoform. These results revealed, for the first time, redundant roles of PLD1 and PLD2 in platelet alpha-granule secretion and indicate that this may be relevant for pathological thrombus formation. Thus, PLD might represent a promising target for antithrombotic therapy. Thus, this hypothesis was tested more directly in the second part of this thesis. The effects of pharmacological inhibition of PLD activity on hemostasis, thrombosis and thrombo-inflammatory brain infarction in mice were assessed. Treatment of platelets with the reversible, small molecule PLD inhibitor 5-Fluoro-2-indolyl des-chlorohalopemide (FIPI) led to a specific blockade of PLD activity that was associated with reduced -granule release and integrin activation. Mice that received FIPI at a dose of 3 mg/kg displayed reduced occlusive thrombus formation upon chemical injury of carotid arteries or mesenterial arterioles. Similarly, FIPI-treated mice had smaller infarct sizes and significantly better motor and neurological function 24 hours after transient middle cerebral artery occlusion. This protective effect was not associated with major intracerebral hemorrhage or prolonged tail bleeding times. Thus, pharmacological PLD inhibition might represent a safe therapeutic strategy to prevent arterial thrombosis or ischemic stroke. After revealing a central role for PLD in thrombo-inflammation, the regulation of PLD activity in platelets was analyzed in the last part of the thesis. Up to date, most studies made use of inhibitors potentially exerting off-target effects and consequently PLD regulation is discussed controversially. Therefore, PLD activity in mice genetically lacking potential modulators of PLD activity was determined to address these controversies. These studies revealed that PLD is tightly regulated during initial platelet activation. While integrin outside-in signaling and Gi signaling was dispensable for PLD activation, it was found that PLC dependent pathways were relevant for the regulation of PLD enzyme activity.},
  subject      = {Phospholipase D},
  language  = {en}
}
@phdthesis{Ruecker2021,
  author    = {R{\"u}cker, Viktoria},
  title     = {Time trends and determinants of stroke mortality in Germany},
  doi       = {10.25972/OPUS-23311},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-233116},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {In several countries, a decline in mortality, case-fatality and recurrence rates of stroke was observed. However, studies investigating sex-specific and subtype-specific (pathological and etiological) time trends in stroke mortality, case-fatality and recurrence rates are scarce, especially in Germany. The decline in ischemic stroke mortality and case-fatality might be associated with the high quality of acute care of ischemic stroke, but the exact determinants of early outcome remains unknown for Germany. Therefore, as first step of this thesis, we investigated the time trends of subtype- and sex-specific age- standardized stroke mortality rates in Germany from 1998 to 2015, by applying joinpoint regression on official causes of death statistics, provided by the Federal Statistical Office. Furthermore, a regional comparison of the time trends in stroke mortality between East and West was conducted. In the second step, time trends in case-fatality and stroke recurrence rates were analyzed using data from a population- based stroke register in Germany between 1996 and 2015. The analysis was stratified by sex and etiological subtype of ischemic stroke. In the third step, quality of stroke care and the association between adherence to measures of quality of acute ischemic stroke care and in-hospital mortality was estimated based on data from nine regional hospital-based stroke registers in Germany from the years 2015 and 2016. We showed that in Germany, age-standardized stroke mortality declined by over 50\% from 1998 to 2015 both, in women and men. Stratified by the pathological subtypes of stroke, the decrease in mortality was larger in ischemic stroke compared to hemorrhagic stroke. Different patterns in the time trends of stroke were observed for stroke subtypes, regions in Germany (former Eastern part of Germany (EG), former Western part of Germany (WG)) and sex, but in all strata a decline was found. By applying joinpoint regression, the number of changes in time trend differed between the regions and up to three changes in the trend in ischemic stroke mortality were detected. Trends in hemorrhagic stroke were in parallel between the regions with up to one change (in women) in joinpoint regression. Comparing the regions, stroke mortality was higher in EG compared to WG throughout the whole observed time period, however the differences between the regions started to diminish from 2007 onwards. Further it was found that, based on the population-based Erlangen Stroke Project (ESPro), case-fatality and recurrence rates in ischemic stroke patients are still high in Germany. 46\% died and 20\% got a recurrent stroke within the first five years after stroke. Case-fatality rates declined statistically significant from 1996 to 2015 across all ischemic stroke patients and all etiological subtypes of ischemic stroke. Based on Cox regression no statistically significant decrease in stroke recurrence was observed. Based on the pooled data of nine regional hospital-based stroke registers from the years 2015 and 2016 covering about 80\% of all hospitalized stroke patients in Germany, a high quality of care of acute ischemic stroke patients, measured via 11 evidence-based quality indicators (QI) of process of care, was observed. Across all registers, most QI reached the predefined target values for good quality of stroke care. 9 out of 11 QI showed a significant association with 7-day in-hospital mortality. An inverse linear association between overall adherence to QI and 7-day in-hospital mortality was observed. In conclusion, stroke mortality and case-fatality showed a favorable development over time in Germany, which might partly be due to improvements in acute treatment. This is supported by the association between overall adherence to quality of care and in-hospital mortality. However, there might be room for improvements in long-term secondary prevention, as no clear reduction in recurrence rates was observed.},
  subject      = {Schlaganfall},
  language  = {en}
}
@phdthesis{Popp2018,
  author    = {Popp, Michael},
  title     = {Mechanisms of platelet activation and receptor regulation in genetically modified mice},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-135494},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {This work summarizes the results of studies on several major aspects of platelet activation and platelet receptor regulation. Therefore, this thesis is divided into four parts. Platelet activation and aggregation at sites of vascular injury is critical to prevent excessive blood loss, but may also lead to life-threatening ischemic disease states, such as myocardial infarction and stroke. Agonist-induced elevation in cytosolic Ca2+ concentrations is essential for platelet activation in hemostasis and thrombosis. The principal route of Ca2+ influx in platelets is store-operated calcium entry (SOCE). The calcium sensor molecule stromal interaction molecule 1 (STIM1) regulates SOCE by activating the membrane calcium channel protein Orai1, but the exact mechanisms of this interaction are not fully understood. Using affinity chromatography to screen for STIM1 interacting proteins in platelets, bridging integrator 2 (BIN2), an adapter protein belonging to the family of BAR proteins that is mainly expressed in the hematopoietic system, was identified. Newly generated BIN2 KO mice were viable and fertile but their platelets displayed markedly impaired SOCE in response to thapsigargin (TG) as well as agonists acting on immunoreceptor tyrosine-based activation motif (ITAM) or G protein-coupled receptors. This SOCE defect resulted in impaired (hem)ITAM induced platelet activation, aggregate formation under flow and procoagulant activity. As a consequence, mice lacking BIN2 in platelets were protected from occlusive arterial thrombus formation and thrombo-inflammatory cerebral infarct progression in a model of experimental stroke. These results identify BIN2 as a critical regulator of platelet SOCE in thrombosis and thrombo-inflammatory disease. Integrin αIIbβ3 plays a central role in the adhesion and aggregation of platelets. Integrin activation requires the transmission of a signal from the small cytoplasmic tails of the α or β subunit to the large extracellular domains resulting in conformational changes of the extracellular domains to enable ligand binding. It was hypothesized that Hic-5 is a novel regulator of integrin αIIbβ3 activation in mice. As demonstrated in the second part of this thesis, lack of Hic-5 had no detectable effect on platelet integrin activation and function in vitro and in vivo under all tested conditions. These results indicate that Hic-5 is dispensable for integrin αIIbβ3 activation and consequently for arterial thrombosis and hemostasis in mice. The Rho GTPase family members RhoA and Rac1 play major roles in platelet activation at sites of vascular injury. Little is known about possible redundant functions of these Rho GTPases in regulating platelet function. To investigate functional redundancies of RhoA and Rac1 in platelet production and function, mice with MK- and platelet-specific double- deficiencies in RhoA and Rac1 were generated. RhoA/Rac1 double-deficiency phenocopied the respective single knockouts without any additional effects in the double-knockout animals, demonstrating for the first time a functional non-redundancy of RhoA and Rac1 in platelet function. Antibodies against platelet glycoproteins (GP) trigger platelet destruction in immune thrombocytopenia (ITP) by binding to Fcγ receptors (FcγRs) on immune cells. However, antibodies against the platelet collagen receptor GPVI exert powerful anti-thrombotic action in vivo by inducing ectodomain shedding of the receptor associated with a transient thrombocytopenia. As shown in the final part of this thesis, blockade or deficiency of the inhibitory FcγRIIB abolished sequestration of anti-GPVI opsonized platelets in the hepatic vasculature and GPVI shedding. This process was mediated by liver sinusoidal endothelial cells (LSEC), the major FcγRIIB expressing cell type in the body. Furthermore, LSEC FcγRIIB mediated hepatic platelet sequestration and contributed to thrombocytopenia in mice treated with antibodies against αIIbβ3, the major target antigen in human ITP. These results reveal a novel and unexpected function of hepatic FcγRIIB in the processing of antibody-opsonized platelets.},
  subject      = {H{\"a}mostase},
  language  = {en}
}
@phdthesis{Leinweber2022,
  author    = {Leinweber, Jonas},
  title     = {Untersuchung zur pathophysiologischen Rolle und therapeutischen Relevanz der neuen Inhibitoren der plasmatischen Blutgerinnung Agaphelin und Ixolaris im experimentellen Schlaganfallmodell der Maus},
  doi       = {10.25972/OPUS-25292},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-252921},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Beim isch{\"a}mischen Schlaganfall f{\"u}hrt ein thrombotischer Verschluss von gehirnversorgenden Arterien zu einer akuten Durchblutungsst{\"o}rung, mit der Folge von neurologischen Defiziten. Prim{\"a}res Therapieziel ist es, diese Blutgerinnsel aufzul{\"o}sen, um die Sauerstoffversorgung des Gehirns wiederherzustellen und den isch{\"a}mischen Hirnschaden zu begrenzen. Dazu stehen die intraven{\"o}sen Thrombolyse mit rt-PA (rekombinanter Gewebe-Plasminogen-Aktivator) sowie die endovaskul{\"a}re mechanische Thrombektomie zur Verf{\"u}gung. H{\"a}ufig kann ein Schlaganfall, trotz erfolgreicher Rekanalisation der Gef{\"a}ße, zu einer weiteren Gr{\"o}ßenzunahme des Infarktes und neurologischen Defiziten bei den Patienten f{\"u}hren. Diese Gr{\"o}ßenzunahme beruht zum einen auf einem sich entwickelnden Hirn{\"o}dem und zum anderen auf entz{\"u}ndlichen Prozessen. Zahlreiche Hinweise deuten darauf hin, dass der Schlaganfall ein Zusammenspiel aus thrombotischen und entz{\"u}ndlichen Ereignissen ist, ein Ph{\"a}nomen, das als Thromboinflammation bezeichnet wird. Aufgrund der begrenzten Behandlungsm{\"o}glichkeiten ist die Entwicklung neuer Therapieans{\"a}tze f{\"u}r den isch{\"a}mischen Schlaganfall besonders wichtig. Agaphelin und Ixolaris sind Proteine aus den Speicheldr{\"u}sen von H{\"a}matophagen, f{\"u}r welche in fr{\"u}heren Studien eine starke antithrombotische Wirkung bei gleichzeitig geringem Blutungsrisiko nachgewiesen wurde. Diese m{\"o}glichen antithrombotischen Effekte wurden in dieser Studie im Hinblick auf ihre Wirksamkeit und Sicherheit im Mausmodell der zerebralen Isch{\"a}mie untersucht. Die Behandlung der M{\"a}use mit Agaphelin 1 Stunde nach transienter Okklusion der Arteria cerebri media (tMCAO) f{\"u}hrte zu kleineren Schlaganfallvolumina und geringeren neurologischen Defiziten an Tag 1 nach dem Schlaganfall. Die Mortalit{\"a}t der M{\"a}use war bis Tag 7 deutlich gesunken. Aus klinischer Sicht ist ebenfalls relevant, dass der starke antithrombotische Effekt von Agaphelin im Mausmodell nicht mit einem erh{\"o}hten Risiko f{\"u}r intrazerebrale Blutungen einherging. Diesem protektiven Effekt von Agaphelin lagen eine verminderte intrazerebrale Thrombusbildung, eine abgeschw{\"a}chte Entz{\"u}ndungsantwort und eine Stabilisierung der Blut-Hirn-Schranke sowie eine Reduzierung der Apoptose zugrunde. Nach der Gabe von Ixolaris 1 Stunde nach tMCAO waren zwar signifikant geringere Infarktgr{\"o}ßen messbar, diese f{\"u}hrten allerdings nicht zu einer Verbesserung der neurologischen Defizite. Zudem verursachte die Gabe von Ixolaris schon 24 Stunden nach tMCAO erhebliche intrazerebrale Blutungen und auch die Mortalit{\"a}t der M{\"a}use war zu diesem Zeitpunkt bereits erh{\"o}ht. Aufgrund dieser massiven Nebenwirkungen scheint Ixolaris kein geeigneter Kandidat f{\"u}r eine humane Anwendung zu sein. Bei Agaphelin hingegen k{\"o}nnte es sich um einen vielversprechenden Kandidaten f{\"u}r die Behandlung des isch{\"a}mischen Schlaganfalls handeln. Vor einer m{\"o}glichen Testung von Agaphelin in klinischen Studien, sind weitere translationale Untersuchungen notwendig, um ein noch pr{\"a}ziseres Verst{\"a}ndnis f{\"u}r die Wirksamkeit und Sicherheit von Agaphelin zu gewinnen. Insgesamt stellt die Hemmung thromboinflammatorischer Prozesse, ohne eine Erh{\"o}hung der Blutungskomplikationen, eine vielversprechende Option zur Behandlung des isch{\"a}mischen Schlaganfalls dar.},
  subject      = {Schlaganfall},
  language  = {de}
}
@phdthesis{JiruHillmann2022,
  author    = {Jir{\`u}-Hillmann, Steffi},
  title     = {Schlaganfallversorgung: Europ{\"a}ische, deutsche und regionale Perspektiven},
  doi       = {10.25972/OPUS-26144},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-261445},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Seit Mitte der 1990er Jahre wurden nationale und regionale Schlaganfallregister in Europa etabliert, die Auskunft {\"u}ber die Versorgungsqualit{\"a}t von Schlaganfallpatienten geben. Bislang lagen nur wenige Daten zu zeitlichen Trends der akuten Schlaganfallversorgung vor. Diese sind jedoch essentiell, um beispielsweise Zusammenh{\"a}nge zwischen der Einf{\"u}hrung potentiell qualit{\"a}tsverbessernder Maßnahmen und der Entwicklung der Versorgungsqualit{\"a}t feststellen zu k{\"o}nnen. Die Behandlung von Schlaganfallpatienten auf Stroke Units ist aufgrund der eindeutigen Evidenz aus randomisierten- und Beobachtungsstudien zum Standard geworden. Bislang war unklar, ob demografische und klinische Charakteristika die direkte Aufnahme auf eine Stroke Unit beeinflussen. Zudem war nicht bekannt, ob und wenn ja, in welchem Ausmaß strukturelle Kriterien und der Anteil der Patienten, der auf eine Stroke Unit aufgenommen wurde, die Qualit{\"a}t der Stroke Unit Versorgung beeinflussen. Im Anschluss an die Akutbehandlung im Krankenhaus bzw. nach geeigneten Rehabilitationsmaßnahmen {\"u}bernehmen pflegende Angeh{\"o}rige h{\"a}ufig die Versorgung der Schlaganfallpatienten im h{\"a}uslichen Umfeld. Die aktuelle Situation der pflegenden Angeh{\"o}rigen von Schlaganfallpatienten in Deutschland ist bisher jedoch nur unzureichend evaluiert. In der vorliegenden Dissertation wurden zun{\"a}chst im Rahmen des „European Implementation Score"-Projektes zeitliche Trends der Qualit{\"a}t der akuten Schlaganfallversorgung in f{\"u}nf nationalen europ{\"a}ischen Schlaganfallregistern aus Deutschland, England/Wales/Nordirland, Polen, Schottland und Schweden nach zuvor definierten evidenzbasierten Qualit{\"a}tsindikatoren berechnet. Im zweiten Schritt wurde anhand von Daten der Arbeitsgemeinschaft Deutscher Schlaganfall Register (ADSR) evaluiert, ob demografische und klinische Patientencharakteristika die direkte Aufnahme auf eine Stroke Unit in Deutschland beeinflussen. Weiterhin wurde der Einfluss struktureller Charakteristika auf die Erf{\"u}llung von 11 evidenzbasierter Qualit{\"a}tsindikatoren in Krankenh{\"a}usern, die {\"u}ber eine regionale oder {\"u}berregionale Stroke Unit verf{\"u}gen, untersucht. Abschließend wurden im Rahmen des regionalen Telemedizinnetzwerkes TRANSIT-Stroke demografische und klinische Charakteristika von Schlaganfallpatienten, die 3 Monate nach dem Schlaganfall mit dem Erhalt von Pflege durch einen Angeh{\"o}rigen assoziiert waren, identifiziert. Zus{\"a}tzlich wurden mit standardisierten Erhebungsinstrumenten positive und negative Erfahrungen der Pflege eines Schlaganfallpatienten sowie die selbsteingesch{\"a}tzte Belastung (deutsche Version des Caregiver Reaction Assessment und Self-Rated Burden Scale) ausgewertet sowie Faktoren, die mit den Pflegeerfahrungen und Belastungen assoziiert sind, evaluiert. Auf europ{\"a}ischer Ebene konnten wir einen Zusammenhang zwischen der Einf{\"u}hrung eines neuen Qualit{\"a}tsindikators und der Verbesserung der Qualit{\"a}t beobachten. Dies galt insbesondere f{\"u}r die erstmalige Einf{\"u}hrung des Qualit{\"a}tsindikators Dysphagiescreening im deutschen -(2006) und schwedischen Schlaganfallregister (2007). Somit gibt es Hinweise darauf, dass das Monitoring der Qualit{\"a}t der Schlaganfallversorgung zu Qualit{\"a}tsverbesserungen bzw. auch zu einer vollst{\"a}ndigeren Dokumentation f{\"u}hrt. Insgesamt konnten wir ein qualitativ hohes Niveau der akuten Schlaganfallversorgung auf Stroke Units in Deutschland gem{\"a}ß evidenzbasierter Qualit{\"a}tsindikatoren feststellen. Patienten mit einem isch{\"a}mischen Schlaganfall, die am Wochenende aufgenommen wurden (p<0,0001), innerhalb von 3 Stunden nach Symptombeginn im Krankenhaus aufgenommen wurden (p<0,0001), hypertensiv waren (p<0,0001), unter einer Hyperlipid{\"a}mie (p<0,0001) litten, wurden mit einer h{\"o}heren Wahrscheinlichkeit auf einer Stroke Unit aufgenommen. Dagegen hatten Patienten mit einem schwereren Schlaganfall (NIHSS>15) eine geringere Chance, auf einer Stroke Unit aufgenommen zu werden (p<0,0001). Der Einfluss struktureller Charakteristika auf die Qualit{\"a}t der Stroke Unit Versorgung war gering. Eine Verbesserung der Qualit{\"a}t k{\"o}nnte noch durch einen h{\"o}heren Anteil der auf einer Stroke Unit aufgenommenen Patienten erreicht werden. Im Rahmen der Nachbefragung von Patienten im regionalen Telemedizinnetzwerk TRANSIT-Stroke stellten Frauen mit 70,1\% den gr{\"o}ßten Anteil der pflegenden Angeh{\"o}rigen dar. 74,4\% der pflegenden Angeh{\"o}rigen war {\"a}lter als 55 Jahre. In univariablen und multivariablen logistischen Regressionsanalysen waren ein hohes Alter, ein niedriger Barthel-Index bei Entlassung sowie das Vorliegen von Diabetes signifikant mit einer h{\"o}heren Wahrscheinlichkeit assoziiert, Pflege von einem Angeh{\"o}rigen zu erhalten. Der Großteil der pflegenden Angeh{\"o}rigen m{\"o}chte den Angeh{\"o}rigen pflegen und ist gleichzeitig dem Risiko gesundheitlicher Probleme ausgesetzt. Circa ein F{\"u}nftel der pflegenden Angeh{\"o}rigen berichtete finanzielle Belastungen aufgrund der Pflegesituation. Depressive Symptome der Patienten waren mit einer h{\"o}heren Belastung der pflegenden Angeh{\"o}rigen hinsichtlich der selbsteingesch{\"a}tzten Belastung und den positiven und negativen Erfahrungen assoziiert. J{\"u}ngere, m{\"a}nnliche Schlaganfallpatienten, mit einem milderen Schlaganfall, die mit einer Partnerin oder Ehepartnerin zusammenleben, scheinen sich oft nicht bewusst zu sein, dass sie Pflege erhalten. M{\"o}glich ist hier, dass sie die Unterst{\"u}tzung und Pflege als „normal" betrachten, w{\"a}hrend der Partner bzw. die Partnerin dies als tats{\"a}chliche Pflege wertet. Schlaganfallregister eignen sich, um die Qualit{\"a}t der Akutversorgung im Zeitverlauf zu monitorieren und Zusammenh{\"a}nge zwischen der Einf{\"u}hrung potentiell qualit{\"a}tsverbessernder Maßnahmen und der tats{\"a}chlichen Qualit{\"a}t darstellen zu k{\"o}nnen. Die Qualit{\"a}t der Stroke Unit Versorgung in Deutschland ist auf einem hohen Niveau. Eine Verbesserung der Qualit{\"a}t k{\"o}nnte noch durch einen h{\"o}heren Anteil der auf einer Stroke Unit aufgenommenen Patienten erreicht werden. Ein Großteil der Schlaganfallpatienten lebt im Anschluss an die Akutversorgung im h{\"a}uslichen Umfeld, in dem pflegende Angeh{\"o}rige eine wichtige Rolle bei der Versorgung spielen. Pflegenden Angeh{\"o}rigen ist ihre Aufgabe wichtig, sind jedoch aufgrund der Pflege zugleich Belastungen hinsichtlich ihrer Gesundheit, der Gestaltung ihres t{\"a}glichen Zeitplans und der Finanzen ausgesetzt.},
  subject      = {Schlaganfall},
  language  = {de}
}
@phdthesis{Heydenreich2013,
  author    = {Heydenreich, Nadine},
  title     = {Studies on the contact-kinin system and macrophage activation in experimental focal cerebral ischemia},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-94534},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {Traditionally, ischemic stroke has been regarded as the mere consequence of cessation of cerebral blood flow, e.g. due to the thromboembolic occlusion of a major brain supplying vessel. However, the simple restoration of blood flow via thrombolysis and/or mechanical recanalization alone often does not guarantee a good functional outcome. It appears that secondary detrimental processes are triggered by hypoxia and reoxygenation, which are referred to as ischemia/reperfusion (I/R) injury. During recent years it became evident that, beside thrombosis inflammation and edema formation are key players in the pathophysiology of cerebral ischemia. The contact-kinin system represents an interface between thrombotic, inflammatory and edematous circuits. It connects the intrinsic coagulation pathway with the plasma kallikrein-kinin system (KKS) via coagulation factor FXII. The serine protease inhibitor C1-inhibitor (C1-INH) has a wide spectrum of inhibitory activities and counteracts activation of the contact-kinin system at multiple levels. The first part of the thesis aimed to multimodally interfere with infarct development by C1-INH and to analyze modes of actions of human plasma derived C1-INH Berinert® P in a murine model of focal cerebral ischemia. It was shown that C57BL/6 mice following early application of 15.0 units (U) C1-INH, but not 7.5 U developed reduced brain infarctions by ~60\% and less neurological deficits in the model of transient occlusion of the middle cerebral artery (tMCAO). This protective effect was preserved at more advanced stages of infarction (day 7), without increasing the risk of intracerebral bleeding or affecting normal hemostasis. Less neurological deficits could also be observed with delayed C1-INH treatment, whereas no improvement was achieved in the model of permanent MCAO (pMCAO). Blood-brain-barrier (BBB) damage, inflammation and thrombosis were significantly improved following 15.0 U C1-INH application early after onset of ischemia. Based on its strong antiedematous, antiinflammatory and antithrombotic properties C1-INH constitutes a multifaceted therapeutic compound that protects from ischemic neurodegeneration in 'clinically meaningful' settings. The second part of the thesis addresses the still elusive functional role of macrophages in the early phase of stroke, especially the role of the macrophage-specific adhesion molecule sialoadhesin (Sn). For the first time, sialoadhesin null (Sn-/-) mice, homozygous deficient for Sn on macrophages were subjected to tMCAO to assess the clinical outcome. Neurological and motor function was significantly improved in Sn-/- mice on day 1 after ischemic stroke compared with wildtype (Sn+/+) animals. These clinical improvements were clearly detectable even on day 3 following tMCAO. Infarctions on day 1 were roughly the same size as in Sn+/+ mice and did not grow until day 3. No intracerebral bleeding could be detected at any time point of data acquisition. Twenty four hours after ischemia a strong induction of Sn was detectable in Sn+/+ mice, which was previously observed only on perivascular macrophages in the normal brain. Deletion of Sn on macrophages resulted in less disturbance of the BBB and a reduced number of CD11b+ (specific marker for macrophages/microglia) cells, which, however, was not associated with altered expression levels of inflammatory cytokines. To further analyze the function of macrophages following stroke this thesis took advantage of LysM-Cre+/-/IKK2-/- mice bearing a nuclear factor (NF)-ϰB activation defect in the myeloid lineage, including macrophages. Consequently, macrophages were not able to synthesize inflammatory cytokines under the control of NF-ϰB. Surprisingly, infarct sizes and neurological deficits upon tMCAO were roughly the same in conditional knockout mice and respective wildtype littermates. These findings provide evidence that macrophages do not contribute to tissue damage and neurological deficits, at least, not by release of inflammatory cytokines in the early phase of cerebral ischemia. In contrast, Sn which is initially expressed on perivascular macrophages and upregulated on macrophages/microglia within the parenchyma following stroke, influenced functional outcome.},
  subject      = {Blut-Hirn-Schranke},
  language  = {en}
}
@phdthesis{GoebneeKlaus2023,
  author    = {G{\"o}b [n{\´e}e Klaus], Vanessa Aline Domenica},
  title     = {Pathomechanisms underlying ischemic stroke},
  doi       = {10.25972/OPUS-28672},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286727},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Every year, stroke affects over 100 million people worldwide and the number of cases continues to grow. Ischemic stroke is the most prevalent form of stroke and rapid restoration of blood flow is the primary therapeutic aim. However, recanalization might fail or reperfusion itself induces detrimental processes leading to infarct progression. Previous studies identified platelets and immune cells as drivers of this so-called ischemia/reperfusion (I/R) injury, establishing the concept of ischemic stroke as thrombo-inflammatory disease. Reduced cerebral blood flow despite recanalization promoted the hypothesis that thrombus formation within the cerebral microcirculation induces further tissue damage. The results presented in this thesis refute this: using complementary methodologies, it was shown that infarct growth precedes the occurrence of thrombi excluding them as I/R injury-underlying cause. Blood brain barrier disruption is one of the hallmarks of ischemic stroke pathology and was confirmed as early event during reperfusion injury in the second part of this study. Abolished platelet α-granule release protects mice from vascular leakage in the early reperfusion phase resulting in smaller infarcts. Using in vitro assays, platelet α-granule-derived PDGF-AB was identified as one factor contributing to blood-brain barrier disruption. In vivo visualization of platelet activation would provide important insights in the spatio-temporal context of platelet activation in stroke pathology. As platelet signaling results in elevated intracellular Ca2+ levels, this is an ideal readout. To overcome the limitations of chemical calcium indicators, a mouse line expressing an endogenous calcium reporter specifically in platelets and megakaryocytes was generated. Presence of the reporter did not interfere with platelet function, consequently these mice were characterized in in vivo and ex vivo models. Upon ischemic stroke, neutrophils are among the first cells that are recruited to the brain. Since for neutrophils both, beneficial and detrimental effects are described, their role was investigated within this thesis. Neither neutrophil depletion nor absence of NADPH-dependent ROS production (Ncf-/- mice) affected stroke outcome. In contrast, abolished NET-formation in Pad4-/- mice resulted in reduced infarct sizes, revealing detrimental effects of NETosis in the context of ischemic stroke, which might become a potential therapeutic target. Cerebral venous (sinus) thrombosis, CV(S)T is a rare type of stroke with mainly idiopathic onset. Whereas for arterial thrombosis a critical contribution of platelets is known and widely accepted, for venous thrombosis this is less clear but considered more and more. In the last part of this thesis, it was shown that fab-fragments of the anti-CLEC-2 antibody INU1 trigger pathological platelet activation in vivo, resulting in foudroyant CVT accompanied by heavy neurological symptoms. Using this novel animal model for CVT, cooperative signaling of the two platelet receptors CLEC-2 and GPIIb/IIIa was revealed as major trigger of CVT and potential target for treatment.},
  subject      = {Schlaganfall},
  language  = {en}
}
@phdthesis{Gorelashvili2019,
  author    = {Gorelashvili, Maximilian Georg},
  title     = {Investigation of megakaryopoiesis and the acute phase of ischemic stroke by advanced fluorescence microscopy},
  doi       = {10.25972/OPUS-18600},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-186002},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {In mammals, anucleate platelets circulate in the blood flow and are primarily responsible for maintaining functional hemostasis. Platelets are generated in the bone marrow (BM) by megakaryocytes (MKs), which mainly reside directly next to the BM sinusoids to release proplatelets into the blood. MKs originate from hematopoietic stem cells and are thought to migrate from the endosteal to the vascular niche during their maturation, a process, which is, despite being intensively investigated, still not fully understood. Long-term intravital two photon microscopy (2PM) of MKs and vasculature in murine bone marrow was performed and mean squared displacement analysis of cell migration was performed. The MKs exhibited no migration, but wobbling-like movement on time scales of 3 h. Directed cell migration always results in non-random spatial distribution. Thus, a computational modelling algorithm simulating random MK distribution using real 3D light-sheet fluorescence microscopy data sets was developed. Direct comparison of real and simulated random MK distributions showed, that MKs exhibit a strong bias to vessel-contact. However, this bias is not caused by cell migration, as non-vessel-associated MKs were randomly distributed in the intervascular space. Furthermore, simulation studies revealed that MKs strongly impair migration of other cells in the bone marrow by acting as large-sized obstacles. MKs are thought to migrate from the regions close to the endosteum towards the vasculature during their maturation process. MK distribution as a function of their localization relative to the endosteal regions of the bones was investigated by light sheet fluorescence microscopy (LSFM). The results show no bone-region dependent distribution of MKs. Taken together, the newly established methods and obtained results refute the model of MK migration during their maturation. Ischemia reperfusion (I/R) injury is a frequent complication of cerebral ischemic stroke, where brain tissue damage occurs despite successful recanalization. Platelets, endothelial cells and immune cells have been demonstrated to affect the progression of I/R injury in experimental mouse models 24 h after recanalization. However, the underlying Pathomechanisms, especially in the first hours after recanalization, are poorly understood. Here, LSFM, 2PM and complemental advanced image analysis workflows were established for investigation of platelets, the vasculature and neutrophils in ischemic brains. Quantitative analysis of thrombus formation in the ipsilateral and contralateral hemispheres at different time points revealed that platelet aggregate formation is minimal during the first 8 h after recanalization and occurs in both hemispheres. Considering that maximal tissue damage already is present at this time point, it can be concluded that infarct progression and neurological damage do not result from platelet aggregated formation. Furthermore, LSFM allowed to confirm neutrophil infiltration into the infarcted hemisphere and, here, the levels of endothelial cell marker PECAM1 were strongly reduced. However, further investigations must be carried out to clearly identify the role of neutrophils and the endothelial cells in I/R injury.},
  subject      = {Fluoreszenzmikroskopie},
  language  = {en}
}
@phdthesis{Fleischer2023,
  author    = {Fleischer, Anna},
  title     = {Durchf{\"u}hrbarkeit und diagnostische Genauigkeit der tragbaren Echokardiographie am Krankenbett von Patienten und Patientinnen mit isch{\"a}mischem Schlaganfall auf Stroke Unit - eine Pilotstudie},
  doi       = {10.25972/OPUS-29654},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-296547},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Beinahe jeder dritte isch{\"a}mische Schlaganfall ist urs{\"a}chlich auf Erkrankungen des Herzens zur{\"u}ckzuf{\"u}hren. Daher empfehlen Leitlinien allen Patienten und Patientinnen, bei denen eine kardioembolische {\"A}tiologie des Schlaganfalls vermutet wird und bei denen ein Vorhofflimmern nicht bereits bekannt ist, als Teil der Routinediagnostik eine echokardiographische Untersuchung, um Hinweise auf die {\"A}tiologie des isch{\"a}mischen Schlaganfalls zu gewinnen und um gegebenenfalls Maßnahmen zur Sekund{\"a}rpr{\"a}vention einleiten zu k{\"o}nnen. Jedoch ist der Zugang zu solchen echokardiographischen Untersuchungen oftmals limitiert, besonders f{\"u}r Patienten und Patientinnen auf Stroke Units, denn dort {\"u}berschreitet die Nachfrage h{\"a}ufig die verf{\"u}gbaren personellen und instrumentellen Kapazit{\"a}ten. Zudem stellt der Transport bettl{\"a}geriger Patienten und Patientinnen in andere Abteilungen eine Belastung dar. Daher stellt sich die Frage, ob zuk{\"u}nftig im Rahmen wissenschaftlicher Studien POC-Echokardiographie-Ger{\"a}te zur Diagnostik bestimmter Herzerkrankungen einschließlich einer systolischen Dysfunktion bei Patienten und Patientinnen mit isch{\"a}mischem Schlaganfall eingesetzt werden k{\"o}nnen, mit dem Ziel Patienten und Patientinnen zu identifizieren, die von einer erweiterten echokardiographischen Untersuchung profitieren k{\"o}nnten. Im Rahmen der vorliegenden prospektiven Validierungsstudie untersuchte eine Studentin 78 Patienten und Patientinnen mit akutem isch{\"a}mischem Schlaganfall mithilfe eines POC-Echokardiographie-Ger{\"a}ts auf der Stroke Unit der Neurologischen Abteilung des Universit{\"a}tsklinikums W{\"u}rzburg. Im Anschluss daran erhielten alle 78 Patienten und Patientinnen eine Kontrolluntersuchung durch eine erfahrene Echokardiographie-Raterin mithilfe eines SE-Ger{\"a}ts in einem externen Herzzentrum. Die diagnostischen Qualit{\"a}ten des POC-Echokardiographie-Ger{\"a}ts f{\"u}r Forschungszwecke zur fokussierten kardialen Diagnostik nach isch{\"a}mischem Schlaganfall im Vergleich zu einer SE-Untersuchung konnten mithilfe der Validierungsstudie best{\"a}tigt werden. Es zeigte sich insbesondere, dass die POC-Echokardiographie f{\"u}r die Detektion einer LVEF≤55\% mit einer Sensitivit{\"a}t von 100\% geeignet war. Um zu evaluieren, ob sich das POC-Echokardiographie-Ger{\"a}t in Zukunft auch in der klinischen Praxis als Screeninginstrument eignet, mit dem Ziel eine individuelle Behandlung von Schlaganfallpatienten und -patientinnen zu gew{\"a}hrleisten, m{\"u}ssen gr{\"o}ßere, prospektive Studien durchgef{\"u}hrt werden, in denen die Fallzahl f{\"u}r bestimmte kardiologische Erkrankungen ausreichend hoch ist.},
  subject      = {Schlaganfall},
  language  = {de}
}
@phdthesis{Deppermann2017,
  author    = {Deppermann, Carsten},
  title     = {The role of platelet granules in thrombosis, hemostasis, stroke and inflammation},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-121010},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {Platelets are small anucleate cell fragments derived from bone marrow megakaryocytes (MKs) and are important players in hemostasis and thrombosis. Platelet granules store factors which are released upon activation. There are three major types of platelet granules: alpha-granules, dense granules and lysosomes. While dense granules contain non-proteinacious factors which support platelet aggregation and adhesion, platelet alpha-granules contain more than 300 different proteins involved in various functions such as inflammation, wound healing and the maintenanceof vascular integrity, however, their functional significance in vivo remains unknown. This thesis summarizes analyses using three mouse models generated to investigate the role of platelet granules in thrombosis, hemostasis, stroke and inflammation. Unc13d-/- mice displayed defective platelet dense granule secretion, which resulted in abrogated thrombosis and hemostasis. Remarkably, Munc13-4-deficient mice were profoundly protected from infarct progression following transient middle cerebral artery occlusion (tMCAO) and this was not associated with increased intracranial bleeding indicating an essential involvementof dense granule secretion in infarct progression but not intracranial hemostasis during acute stroke with obvious therapeutic implications. In the second part of this thesis, the role of platelet alpha-granules was investigated using the Nbeal2-/- mouse. Mutations in NBEAL2 have been linked to the gray platelet syndrome (GPS), a rare inherited bleeding disorder. Nbeal2-/- mice displayed the characteristics of human GPS, with defective alpha-granule biogenesis in MKs and their absence from platelets. Nbeal2-deficiency did not affect MK differentiation and proplatelet formation in vitro or platelet life span in vivo. Nbeal2-/- platelets displayed impaired adhesion, aggregation, and coagulant activity ex vivo that translated into defective arterial thrombus formation and protection from thrombo-inflammatory brain infarction in vivo. In a model of skin wound repair, Nbeal2-/- mice exhibited impaired development of functional granulation tissue due to severely reduced differentiation of myofibroblasts. In the third part, the effects of combined deficiency of alpha- and dense granule secretion were analyzed using Unc13d-/-/Nbeal2-/- mice. Platelets of these mice showed impaired aggregation and adhesion to collagen under flow ex vivo, which translated into infinite tail bleeding times and severely defective arterial thrombus formation in vivo. When subjected to in vivo models of skin or lung inflammation, the double mutant mice showed no signs of hemorrhage. In contrast, lack of platelet granule release resulted in impaired vascular integrity in the ischemic brain following tMCAO leading to increased mortality. This indicates that while defective dense granule secretion or the paucity of alpha-granules alone have no effect on vascular integrity after stroke, the combination of both impairs vascular integrity and causes an increase in mortality.},
  subject      = {Thrombozyten},
  language  = {en}
}