@phdthesis{Leimbach2017,
  author    = {Leimbach, Andreas},
  title     = {Genomics of pathogenic and commensal \(Escherichia\) \(coli\)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154539},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {High-throughput sequencing (HTS) has revolutionized bacterial genomics. Its unparalleled sensitivity has opened the door to analyzing bacterial evolution and population genomics, dispersion of mobile genetic elements (MGEs), and within-host adaptation of pathogens, such as Escherichia coli. One of the defining characteristics of intestinal pathogenic E. coli (IPEC) pathotypes is a specific repertoire of virulence factors (VFs). Many of these IPEC VFs are used as typing markers in public health laboratories to monitor outbreaks and guide treatment options. Instead, extraintestinal pathogenic E. coli (ExPEC) isolates are genotypically diverse and harbor a varied set of VFs -- the majority of which also function as fitness factors (FFs) for gastrointestinal colonization. The aim of this thesis was the genomic characterization of pathogenic and commensal E. coli with respect to their virulence- and antibiotic resistance-associated gene content as well as phylogenetic background. In order to conduct the comparative analyses, I created a database of E. coli VFs, ecoli_VF_collection, with a focus on ExPEC virulence-associated proteins (Leimbach, 2016b). Furthermore, I wrote a suite of scripts and pipelines, bac-genomics-scripts, that are useful for bacterial genomics (Leimbach, 2016a). This compilation includes tools for assembly and annotation as well as comparative genomics analyses, like multi-locus sequence typing (MLST), assignment of Clusters of Orthologous Groups (COG) categories, searching for protein homologs, detection of genomic regions of difference (RODs), and calculating pan-genome-wide association statistics. Using these tools we were able to determine the prevalence of 18 autotransporters (ATs) in a large, phylogenetically heterogeneous strain panel and demonstrate that many AT proteins are not associated with E. coli pathotypes. According to multivariate analyses and statistics the distribution of AT variants is instead significantly dependent on phylogenetic lineages. As a consequence, ATs are not suitable to serve as pathotype markers (Zude et al., 2014). During the German Shiga toxin-producing E. coli (STEC) outbreak in 2011, the largest to date, we were one of the teams capable of analyzing the genomic features of two isolates. Based on MLST and detection of orthologous proteins to known E. coli reference genomes the close phylogenetic relationship and overall genome similarity to enteroaggregative E. coli (EAEC) 55989 was revealed. In particular, we identified VFs of both STEC and EAEC pathotypes, most importantly the prophage-encoded Shiga toxin (Stx) and the pAA-type plasmid harboring aggregative adherence fimbriae. As a result, we could show that the epidemic was caused by an unusual hybrid pathotype of the O104:H4 serotype. Moreover, we detected the basis of the antibiotic multi-resistant phenotype on an extended-spectrum beta-lactamase (ESBL) plasmid through comparisons to reference plasmids. With this information we proposed an evolutionary horizontal gene transfer (HGT) model for the possible emergence of the pathogen (Brzuszkiewicz et al., 2011). Similarly to ExPEC, E. coli isolates of bovine mastitis are genotypically and phenotypically highly diverse and many studies struggled to determine a positive association of putative VFs. Instead the general E. coli pathogen-associated molecular pattern (PAMP), lipopolysaccharide (LPS), is implicated as a deciding factor for intramammary inflammation. Nevertheless, a mammary pathogenic E. coli (MPEC) pathotype was proposed presumably encompassing strains more adapted to elicit bovine mastitis with virulence traits differentiating them from commensals. We sequenced eight E. coli isolates from udder serous exudate and six fecal commensals (Leimbach et al., 2016). Two mastitis isolate genomes were closed to a finished-grade quality (Leimbach et al., 2015). The genomic sequence of mastitis-associated E. coli (MAEC) strain 1303 was used to elucidate the biosynthesis gene cluster of its O70 LPS O-antigen. We analyzed the phylogenetic genealogy of our strain panel plus eleven bovine-associated E. coli reference strains and found that commensal or MAEC could not be unambiguously allocated to specific phylogroups within a core genome tree of reference E. coli. A thorough gene content analysis could not identify functional convergence of either commensal or MAEC, instead both have only very few gene families enriched in either pathotype. Most importantly, gene content and ecoli_VF_collection analyses showed that no virulence determinants are significantly associated with MAEC in comparison to bovine fecal commensals, disproving the MPEC hypothesis. The genetic repertoire of bovine-associated E. coli, again, is dominated by phylogenetic background. This is also mostly the case for large virulence-associated E. coli gene cluster previously associated with mastitis. Correspondingly, MAEC are facultative and opportunistic pathogens recruited from the bovine commensal gastrointestinal microbiota (Leimbach et al., 2017). Thus, E. coli mastitis should be prevented rather than treated, as antibiotics and vaccines have not proven effective. Although traditional E. coli pathotypes serve a purpose for diagnostics and treatment, it is clear that the current typing system is an oversimplification of E. coli's genomic plasticity. Whole genome sequencing (WGS) revealed many nuances of pathogenic E. coli, including emerging hybrid or heteropathogenic pathotypes. Diagnostic and public health microbiology need to embrace the future by implementing HTS techniques to target patient care and infection control more efficiently.},
  subject      = {Escherichia coli},
  language  = {en}
}
@phdthesis{Langer2017,
  author    = {Langer, Simon},
  title     = {Herz-Hirn Interaktion im Mausmodell: Herzinsuffizienz nach Myokardinfarkt f{\"u}hrt zu depressivem Verhalten bei M{\"a}usen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154733},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {Herzinsuffizienz, Depression und Angstst{\"o}rungen treten geh{\"a}uft gemeinsam auf und beeinflussen teilweise gegenseitig ihre Prognose. Die Zusammenh{\"a}nge zwischen diesen Erkrankungen sind bislang nicht aufgekl{\"a}rt. In der vorliegenden Arbeit f{\"u}hrte isch{\"a}mische Herzinsuffizienz im Mausmodell zu Depressions-{\"a}hnlichem Verhalten innerhalb von 8 Wochen nach Infarktinduktion. Weiter zeigte sich eine Minderung der Ged{\"a}chtnisleistung. Angst-assoziiertes Verhalten ließ sich nicht nachweisen. Immunhistochemisch konnten keine Ver{\"a}nderungen in spezifischen Hirnarealen nachgewiesen werden. Molekulare Methoden legen Ver{\"a}nderungen des Serotoninstoffwechsels als m{\"o}gliche Erkl{\"a}rung nahe. Nach operativer Ligatur eines Herzkrankgef{\"a}ßes wurden C57/Bl6N M{\"a}use {\"u}ber einen Zeitraum von 8 Wochen beobachtet. In dieser Zeit wurden neben Herzultraschalluntersuchungen eine Reihe von Verhaltenstest durchgef{\"u}hrt, um depressive und {\"a}ngstliche Verhaltensstrukturen sowie die kognitive Leistungsf{\"a}higkeit beurteilen zu k{\"o}nnen. Nach Ablauf des Beobachtungszeitraumes wurden das Herz und das Gehirn entnommen und weiteren histologischen und molekularen Untersuchungen zugef{\"u}hrt. Die histologische Aufarbeitung des Herzens nach Ende des Versuchszeitraumes best{\"a}tigte die Beobachtungen anderen Autoren, dass eine Infarktgr{\"o}ße von mehr als 30\% mit sehr hoher Wahrscheinlichkeit zur Entstehung einer Herzinsuffizienz f{\"u}hrt. Im der histologischen Aufarbeitung des Gehirns zeigen sich keine strukturellen Ver{\"a}nderungen bei herzkranken M{\"a}usen, die die beobachteten {\"A}nderungen im Verhalten begr{\"u}nden k{\"o}nnten. Insbesondere kann eine hypoxische Hirnsch{\"a}digung durch eine etwaige Minderperfusion empfindlicher Hirnareale ausgeschlossen werden. M{\"a}use, die nach Induktion eines Myokardinfarktes eine Herzinsuffizienz entwickeln, zeigen nach 8 Wochen Depressions-assoziiertes, adynamisches Verhalten sowie eine Verminderung der kognitiven Leistungsf{\"a}higkeit, nicht aber Anzeichen von Angstst{\"o}rungen. Diesen Verhaltens{\"a}nderungen kann kein strukturelles Korrelat im Gehirn zugewiesen werden. Dies ist ein Indiz daf{\"u}r, dass sich Ver{\"a}nderung auf molekularer Ebene vollziehen, welche sich dem Mikroskop entziehen. Die im Myokard beobachtete Regulation des Serotoninstoffwechsels ist ein m{\"o}glicher Erkl{\"a}rungsansatz hierf{\"u}r.},
  subject      = {Deutsches Zentrum f{\"u}r Herzinsuffizienz W{\"u}rzburg},
  language  = {de}
}
@techreport{Kleinsorg2017,
  type      = {Working Paper},
  author    = {Kleinsorg, Lea Kristin},
  title     = {Die Entwicklung der Staatlichkeit der Republik Gambia w{\"a}hrend Yahya Jammehs Amtszeit},
  issn      = {2199-4315},
  doi       = {10.25972/OPUS-15450},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154500},
  pages     = {71},
  year      = {2017},
  abstract  = {Die westafrikanische Republik Gambia wurde zwei Jahrzehnte lang von Yayha Jammeh regiert. 1994 putschte er sich an die Macht und behielt diese vier Legislaturperioden lang, bis er im Dezember 2016 die Pr{\"a}sidentschaftswahlen {\"u}berraschend gegen seinen Konkurrenten Adama Barrow verlor. Die vorliegende Arbeit untersucht die Entwicklung der Staatlichkeit der Republik Gambia w{\"a}hrend Jammehs Amtszeit. F{\"u}r den Zeitraum seit der Staatsgr{\"u}ndung im Jahr 1965 bis zur ersten Erhebung durch den US-amerikanischen Think Tank Fund for Peace 2006 gibt es keine umfassende Untersuchung {\"u}ber den Zustand der gambischen Staatlichkeit. Durch die Anwendung der Theorie fragiler Staatlichkeit nach Ulrich Schneckener soll mit der vorliegenden Arbeit ein Teil dieser L{\"u}cke geschlossen werden. Dazu werden f{\"u}r jede der vier Legislaturperioden Jammehs die von Schneckener benannten Staatsfunktionen (Sicherheit, Legitimit{\"a}t/Rechtsstaatlichkeit, Wohlfahrt) einzeln untersucht, um anschließend den Zustand der Staatlichkeit Gambias einzuordnen. Dazu werden sowohl quantitative als auch qualitative Daten einschließlich Experteninterviews verwendet. Anhand eines Vergleichs der einzelnen Typologisierungen ist es m{\"o}glich, abschließend ein Gesamtbild der Entwicklung der gambischen Staatlichkeit w{\"a}hrend Jammehs Amtszeit zu zeichnen.},
  subject      = {Gambia},
  language  = {de}
}
@phdthesis{Svistunov2017,
  author    = {Svistunov, Andrey},
  title     = {Langzeitergebnisse der Erhaltungstherapie mit Gemcitabin nach Cisplatin-basierter adjuvanter Chemotherapie des operativ behandelten muskelinfiltrierenden Urothelkarzinoms},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154666},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {Der Stellenwert der Erhaltungstherapie mit Gemcitabin (GEM), die im Anschluss an die Cisplatin-basierte Polychemotherapie (CBPC) bei den radikal operativ vorbehandelten Patienten mit fortgeschrittenem Urothelkarzinom (UC) erfolgt, bleibt bis dato unklar. In der vorliegenden Arbeit konnten die Ergebnisse der GEM-Erhaltungstherapie mittels retrospektiver Analyse evaluiert werden. Zwischen 1999 und 2013 erhielten 38 operativ vorbehandelte Patienten im Anschluss an die prim{\"a}re CBPC zus{\"a}tzlich im viertelj{\"a}hrlichen Intervall zwei konsekutive Infusionen von GEM (1 250 mg/m2) als Erhaltungstherapie. Dieses Kollektiv wurde durch ein ebenso operativ vorbehandeltes Kontrollkollektiv (n = 38), das lediglich eine prim{\"a}re CBPC erhielt, mittels eines `Propensity Score Matching`-Verfahrens gematched. Mittels Kaplan-Meier-Sch{\"a}tzungen mitsamt dem Log-rank-Test wurden die Gesamt{\"u}berlebens- und tumorspezifische {\"U}berlebensraten sowie das progressionsfreie {\"U}berleben in beiden Kollektiven beurteilt. Die Analyse der {\"U}berlebensdaten erfolgte durch die Regressionsmethode nach Cox (proportionales Hazard Modell). Die mediane Follow-Up Zeit betrug 37 Monate bei einem Interquartilsabstand von 9 bis 148 Monaten. Die Patienten, die die GEM-Erhaltungstherapie erhielten, zeigten signifikant bessere Ergebnisse bez{\"u}glich der Gesamt-5-Jahres-{\"U}berlebensrate (49,2 vs. 26,5 \%, p = 0,0314) sowie der tumorspezifischen 5-Jahres-{\"U}berlebensrate (61,3 vs. 33,4 \%, p = 0,0386). Dabei ergab sich in beiden Kollektiven kein statistisch signifikanter Unterschied bez{\"u}glich des progressionsfreien 5-Jahres-{\"U}berlebens (10,3 vs. 16,1 \%, p = 0,134). Es ist dargelegt, dass die zus{\"a}tzliche GEM-Erhaltungschemotherapie nach Abschluss der prim{\"a}ren CBPC bei operativ vorbehandelten Patienten mit fortgeschrittenem UC sowohl Gesamt- als auch tumorspezifisches {\"U}berleben (wenngleich an einem kleinen Patientenkollektiv) verbessern kann. Der Einfluss der GEM-Erhaltungstherapie auf das progressionsfreie {\"U}berleben sollte in prospektiven Studien mit großer Patientenanzahl k{\"u}nftig evaluiert werden.},
  subject      = {Gemcitabin},
  language  = {de}
}
@phdthesis{StelzergebNagel2017,
  author    = {Stelzer [geb. Nagel], Corinna},
  title     = {Effekte der nicht-invasiven aurikul{\"a}ren Vagusnervstimulation auf Hirnaktivierungsmuster, kognitive Parameter und Befindlichkeit},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154717},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {In der vorliegenden prospektiven Pilotstudie wurden die Hypothesen {\"u}berpr{\"u}ft, dass es durch die nicht-invasive aurikul{\"a}re Vagusnervstimulation, jedoch nicht durch eine Kontrollstimulation am Ohrl{\"a}ppchen (Innervationsgebiet des N. trigeminus) zu einer mittels NIRS messbaren Zunahme des regionalen zerebralen Blutflusses und damit der kortikalen Aktivit{\"a}t im Bereich des pr{\"a}frontalen Kortex, zu einer Steigerung der Befindlichkeit und zu einer Verbesserung der Kognition kommt. Die Ergebnisse zeigten eine Deaktivierung im Bereich des pr{\"a}frontalen Kortex, wobei keine signifikanten Unterschiede zwischen der Vagusnerv- und der Kontrollstimulation in allen drei Modulen (Hirnaktivierung, Kognition, Befindlichkeit) nachweisbar waren.},
  subject      = {Vagus},
  language  = {de}
}
@phdthesis{Steiger2017,
  author    = {Steiger, Christoph},
  title     = {Drug delivery of therapeutic gases - strategies for controlled and local delivery of carbon monoxide},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141054},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {The isoenzyme heme oxygenase 1 (HO-1) is a key element for maintaining cellular homeostasis. Upregulated in response to cellular stress, the HO-1 degrades heme into carbon monoxide (CO), biliverdin, and Fe2+. By means of a local cell-protective feedback loop the enzyme triggers numerous effects including anti-oxidative, anti-apoptotic, and anti-inflammatory events associated with complex signalling patterns which are largely orchestrated by CO. Various approaches to mimic this physiological HO-1 / CO system aiming for a treatment of medical conditions have been described [1]. These preclinical studies commonly applied CO systemically via (i) inhalation or (ii) using CO-Releasing Molecules (CORMs) [2]. The clinical use of these approaches, however, is challenged by a lack of practicability and substantial safety issues associated with the toxicity of high systemic doses of CO that are required for triggering therapeutic effects. Therefore, one rational of this thesis is to describe and evaluate strategies for the local delivery of CO aiming for safe and effective CO therapeutics of tomorrow.},
  subject      = {Targeted drug delivery},
  language  = {en}
}
@phdthesis{Konieczka2017,
  author    = {Konieczka, Szymon Zbigniew},
  title     = {Untersuchungen zu neuen polyhalogenierten Aminocarba-\(closo\)-dodecaboraten},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-122548},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {Die Arbeit umfasst zum einen Untersuchungen zu hochhalogenierten 1-Aminocarba-closo-dodecaboraten, zum anderen Untersuchungen zu hochfluorierten Aminocarba-closo-dodecaboraten mit einer an ein Boratom gebundenen Amino-Funktion. Außerdem wurden im diesem Zuge closo-Undecaborat-Cluster untersucht, da diese als interessante Ausgangsverbindungen f{\"u}r funktionalisierte {CB11}-Derivate eingesetzt werden k{\"o}nnen.},
  subject      = {carborane},
  language  = {de}
}
@phdthesis{Iltzsche2017,
  author    = {Iltzsche, Fabian},
  title     = {The Role of DREAM/MMB-mediated mitotic gene expression downstream of mutated K-Ras in lung cancer},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-154108},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {The evolutionary conserved Myb-MuvB (MMB) multiprotein complex has an essential role in transcriptional activation of mitotic genes. MMB target genes as well as the MMB associated transcription factor B-Myb and FoxM1 are highly expressed in a range of different cancer types. The elevated expression of these genes correlates with an advanced tumor state and a poor prognosis. This suggests that MMB could contribute to tumorigenesis by mediating overexpression of mitotic genes. Although MMB has been extensively characterized biochemically, the requirement for MMB to tumorigenesis in vivo remains largely unknown and has not been tested directly so far. In this study, conditional knockout of the MMB core member Lin9 inhibits tumor formation in vivo in a mouse model of lung cancer driven by oncogenic K-Ras and loss of p53. The incomplete recombination observed within tumors points towards an enormous selection pressure against the complete loss of Lin9. RNA interference (RNAi)-mediated depletion of Lin9 or the MMB associated subunit B-Myb provides evidence that MMB is required for the expression of mitotic genes in lung cancer cells. Moreover, it was demonstrated that proliferation of lung cancer cells strongly depends on MMB. Furthermore, in this study, the relationship of MMB to the p53 tumor suppressor was investigated in a primary lung cancer cell line with restorable p53 function. Expression analysis revealed that mitotic genes are downregulated after p53 re-expression. Moreover, activation of p53 induces formation of the repressive DREAM complex and results in enrichment of DREAM at mitotic gene promoters. Conversely, MMB is displaced at these promoters. Based on these findings the following model is proposed: In p53-negative cells, mitogenic stimuli foster the switch from DREAM to MMB. Thus, mitotic genes are overexpressed and may promote chromosomal instability and tumorigenesis. This study provides evidence that MMB contributes to the upregulation of G2/M phase-specific genes in p53-negative cells and suggests that inhibition of MMB (or its target genes) might be a strategy for treatment of lung cancer.},
  subject      = {Nicht-kleinzelliges Bronchialkarzinom (NSCLC)},
  language  = {en}
}
@phdthesis{Lyga2017,
  author    = {Lyga, Sandra},
  title     = {Glycoprotein hormone receptor signaling in the endosomal compartment},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139994},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {G protein-coupled receptors (GPCRs) are the major group of cell-surface receptors that transmit extracellular signals via classical, G protein-dependent pathways into the cell. Although GPCRs were long assumed to signal exclusively from the cell-surface, recent investigations have demonstrated a possibly completely new paradigm. In this new view, GPCR continues signaling via 3´,5´-cyclic adenosine monophosphate (cAMP) after their agonist-induced internalization of ligand/receptor complexes into an intracellular compartment, causing persistent cAMP elevation and apparently specific signaling outcomes. The thyroid stimulating hormone (TSH) receptor is one of the first GPCRs, which has been reported to show persistent signaling after ligand removal (Calebiro et al., 2009). In the meantime, signaling by internalized GPCR become a highly investigated topic and has been shown for several GPCRs, including the parathyroid hormone receptor (Ferrandon et al., 2009), D1 dopamine receptor (Kotowski et al., 2011) and beta2-adrenergic receptor (Irannejad et al., 2013). A recent study on the beta2-adrenergic receptor revealed that internalized receptor not only participates in cAMP signaling, but is also involved in gene transcription (Tsvetanova and von Zastrow, 2014). However, a biological effect of GPCR signaling at intracellular sites, which would demonstrate its physiological relevance, still remained to be shown. To investigate GPCR signaling from intracellular compartment under physiological condition, two different cellular models were utilized in the present study: intact ovarian follicles expressing luteinizing hormone (LH) receptors and primary thyroid cells expressing TSH receptors. Intact ovarian follicles were obtained from a transgenic mouse expressing, a F{\"o}rster/Fluorescence Resonance Energy Transfer (FRET) sensor for cAMP to monitor cAMP/LH receptor signaling. This study provides the first accurate spatiotemporal characterization of cAMP signaling, which is derived from different cell layers of an intact ovarian follicle. Additionally, it could be shown that cAMP diffusion via gap junctions is implicated in spreading the LH-induced cAMP signals from one the outermost (mural granulosa) to the innermost (cumulus oophorus) cell layer of an ovarian follicle. Interestingly, LH receptor stimulation was associated with persistent cAMP signaling after LH removal and negligible desensitization of the cAMP signal. Interfering with receptor internalization with a dynamin inhibitor dynasore did not only prevent persistent LH-induced cAMP signaling, but also impaired the resumption of meiosis in follicle-enclosed oocytes, a key biological effect of LH. In order to investigate the downstream activation of protein kinase A (PKA) in primary thyroid cells, FRET sensors with different subcellular localization (plasma membrane, cytosol and nucleus) were transiently transfected into primary thyroid cells of wild-type mice via electroporation. Interestingly, TSH stimulation causes at least two distinct phases of PKA activation in the global primary thyroid cell, which are temporally separated by approximately 2 min. In addition, PKA activation in different subcellular compartments are characterized by dissimilar kinetics and amplitudes. Pharmacological inhibition of TSH receptor internalization largely prevented the second (i.e. late) phase of PKA activation as well as the subsequent TSH-dependent phosphorylation of CREB and TSH-dependent induction of early genes. These results suggest that PKA activation and nuclear signaling require internalization of the TSH receptor. Taken together, the data of the present study provide strong evidence that GPCR signaling at intracellular sites is distinct from the one occurring at the cell-surface and is highly physiologically relevant.},
  subject      = {GPCR},
  language  = {en}
}
@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}
}