ediss captures, stores, indexes, preserves, and distributes digital research material. https://ediss.sub.uni-hamburg.de:443 2026-04-14T00:10:35Z 2026-04-14T00:10:35Z Formanski, Jan Patrick https://ediss.sub.uni-hamburg.de:443/handle/ediss/12318 2026-04-13T23:34:40Z 2026-04-13T14:21:35Z

Title: Stem cell marker analysis of glioblastoma tumor cells and infection studies using Zika virus protein E pseudotyped lentiviral particles Authors: Formanski, Jan Patrick Abstract: As part of this study, a novel cell culture system for glioblastoma (GBM) cells was developed. For this purpose, GBM tumor samples from areas adjacent to the subventricular zone (SVZ) were used. These areas contain many GBM stem cells (GSCs) and astrocyte-like stem cells. It was demonstrated that the cell cultures maintained their heterogeneity for at least three months when cultured in CSF-DF medium. Based on these findings, a system was developed that enables examination of primary GBM tumor cells under conditions that closely resemble the in vivo environment. In total, twelve primary cell cultures were successfully established (AKH-14 to AKH-24C). Immunological examination of the primary cell cultures revealed the presence of both stem cell- and GBM-specific markers, as well as the surface proteins AXL/Gas6 and integrin αvβ5, which act as entry receptors for the Zika virus (ZIKV). Expression of the stem cell markers OCT4, SOX2, NANOG, Nestin, integrin α6, CD44, and CD133 was detected in the cell cultures. The GBM markers EGFR and PD-1 were overexpressed in all primary cell cultures. Additionally, the isolation of astrocyte-like stem cells was demonstrated by the expression of glial fibrillary acidic protein (GFAP). Immunological analyses revealed that each cell culture exhibited a distinct biomarker expression pattern, suggesting the existence of many different GSC subpopulations. The two ZIKV receptors, AXL/Gas6 and integrin αvβ5, were successfully detected in all primary cell cultures. This study also involved the development of a pseudotype system in which the transmembrane and cytoplasmic (TMCY) region of ZIKV was replaced with that of vesicular stomatitis virus (VSV-G). This approach differs from methods previously established within the working group. The ZIKV E protein was cloned into two expression vectors, pCMV-VSV-G and pMD2.G, to produce the expression vectors pCMV-EG1 and pMD2-EG2. These constructs were used in combination with the packaging plasmid pNLgfpAM to produce the pseudotypes EG1-HIVgfp and EG2-HIVgfp. Infection experiments with both pseudotypes demonstrated successful infection of the primary cell cultures AKH-13, AKH-14, AKH-17, AKH-19, AKH-23, and AKH-24C.

2026-04-13T14:21:35Z Ostrowski, Jan https://ediss.sub.uni-hamburg.de:443/handle/ediss/12288 2026-04-13T23:34:05Z 2026-04-13T14:01:16Z

Title: Rhythms of Association: Pre-stimulus Brain States and the Formation of Multisensory Memory Authors: Ostrowski, Jan Abstract: The ability to form memories of multisensory experiences is strongly tied to different types of electrophysiological activity exhibited by different areas of the brain. Among those, theta (3-7 Hz) and alpha (8-12 Hz) oscillations have been shown to be heavily involved in processes of binding information for subsequent memory encoding, as well as inhibiting interfering information in favor of process optimization. However, the brain is always active, exhibiting ongoing oscillatory activity even in the absence of stimulation. The goal of this dissertation was to investigate how these ongoing, pre-stimulus brain states affect the formation of multisensory associations in service to memory. Three empirical studies were conducted in an attempt to shed light on this question. In the first study, participants were required to memorize individual associations between semantically unrelated images and sounds in the context of a Subsequent Memory Effects paradigm. The findings show that later remembered associations exhibited significant increases in theta as well as alpha activity before the stimulus was even presented, suggesting that pre-stimulus low-frequency oscillations are an important correlate of memory success. Based on these results, a modified version of the SME paradigm was used in the second study, in which visual sensory stimulation was utilized to actively modulate theta and alpha activity before encoding happened. The study demonstrated that visual stimulation in the alpha band can significantly increase memory performance as compared to controls, suggesting that pre-stimulus alpha activity may be functionally relevant to the process of encoding multisensory associations. In the third study, the same audiovisual stimulus pairs were presented sequentially rather than simultaneously to assess whether modality order affects subsequent encoding, and whether it can be treated as a contextual feature in the memory trace. The findings suggest a modality-dependent correlation of low-frequency oscillation before and during encoding with subsequent memory performance, suggesting that the order in which sensory information arrives in the brain can affect ongoing and stimulus-evoked brain states. Taken together, these observations point towards a division of labor between theta and alpha oscillations, expanding the notion of binding and inhibition to the domain of ongoing pre-stimulus oscillatory states. The evidence supports the idea that the ability to memorize experiences does not start with having something to experience, but with the state the brain is in before the experience and its encoding begins. Although not without limitations, these insights contribute to our understanding of how the phenomenon of memory comes to be, and may further contribute to future work in clinical and non-clinical settings.

2026-04-13T14:01:16Z Alizadeh, Arzu https://ediss.sub.uni-hamburg.de:443/handle/ediss/12310 2026-04-13T23:34:23Z 2026-04-13T13:50:10Z

Title: Entzündliche Effekte von Serum Amyloid A in murinen Fettzellen Authors: Alizadeh, Arzu Abstract: Adipositas ist gekennzeichnet durch Entwicklung eines chronisch inflammatorischen Zustandes. Dabei haben Studien wiederholt gezeigt, dass vor allem vom Fettgewebe ausgeschüttete zirkulierende Entzündungsmediatoren mit Komplikationen wie kardiovaskulären Ereignissen oder der Insulinresistenz einhergehen können. Das Akut-Phase-Protein SAA konnte als ein solcher Mediator ausgemacht werden und eine Korrelation der Plasmakonzentration mit der Fettgewebsmasse nachgewiesen werden, sowie dessen Assoziation mit entstehenden Komorbiditäten. Die molekularen Pathomechanismen innerhalb der Adipozyten sind nach wie vor Gegenstand der Forschung. Diese Arbeit geht der Frage nach, welchen Einfluss SAA auf die in Fettzellen ablaufenden Entzündungsvorgänge hat und wie es kausal zu Genexpressionsänderungen und zur Sezernierung von Mediatoren im Entzündungsgeschehen beiträgt.

2026-04-13T13:50:10Z Renken, Emma Paulina https://ediss.sub.uni-hamburg.de:443/handle/ediss/12316 2026-04-13T23:34:42Z 2026-04-13T11:58:22Z

Title: Klinische Endpunkte bei autoimmuner Hepatitis: 15-Jahres-Follow-Up eines Referenzzentrums für immunvermittelte Lebererkrankungen Authors: Renken, Emma Paulina

2026-04-13T11:58:22Z