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Biofabrication technologies must address numerous parameters and conditions to reconstruct tissue complexity in vitro. A critical challenge is vascularization, especially for large constructs exceeding diffusion limits. This requires the creation of artificial vascular structures, a task demanding the convergence and integration of multiple engineering approaches. This doctoral dissertation aims to achieve two primary objectives: firstly, to implement and refine engineering methods for creating artificial microvascular structures using Melt Electrowriting (MEW)-assisted sacrificial templating, and secondly, to deepen the understanding of the critical factors influencing the printability of bioink formulations in 3D extrusion bioprinting.
In the first part of this dissertation, two innovative sacrificial templating techniques using MEW are explored. Utilizing a carbohydrate glass as a fugitive material, a pioneering advancement in the processing of sugars with MEW with a resolution under 100 microns was made. Furthermore, by introducing the “print-and-fuse” strategy as a groundbreaking method, biomimetic branching microchannels embedded in hydrogel matrices were fabricated, which can then be endothelialized to mirror in vivo vascular conditions.
The second part of the dissertation explores extrusion bioprinting. By introducing a simple binary bioink formulation, the correlation between physical properties and printability was showcased. In the next step, employing state-of-the-art machine-learning approaches revealed a deeper understanding of the correlations between bioink properties and printability in an extended library of hydrogel formulations.
This dissertation offers in-depth insights into two key biofabrication technologies. Future work could merge these into hybrid methods for the fabrication of vascularized constructs, combining MEW's precision with fine-tuned bioink properties in automated extrusion bioprinting.
Adoptive immunotherapy using chimeric antigen receptor (CAR)-modified T cells is an effective treatment for hematological malignancies that are refractory to conventional chemotherapy. To address a wider variety of cancer entities, there is a need to identify and characterize additional target antigens for CAR-T cell therapy. The two members of the receptor tyrosine kinase-like orphan receptor family, ROR1 and ROR2, have been found to be overexpressed on cancer cells and to correlate with aggressive cancer phenotypes. Recently, ROR1-specific CAR-T cells have entered testing in phase I clinical trials, encouraging us to assess the suitability of ROR2 as a novel target for CAR-T cell therapy. To study the therapeutic potential of targeting ROR2 in solid and hematological malignancies, we selected two representative cancer entities with high unmet medical need: renal cell carcinoma and multiple myeloma.
Our data show that ROR2 is commonly expressed on primary samples and cell lines of clear cell renal cell carcinoma and multiple myeloma. To study the efficacy of ROR2-specific CAR T cell therapy, we designed two CAR constructs with 10-fold binding affinity differences for the same epitope of ROR2. We found both cell products to exhibit antigen-specific anti-tumor reactivity in vitro, including tumor cell lysis, secretion of the effector cytokines interleukin-2 (IL-2) and interferon-gamma (IFNγ), and T cell proliferation. In vivo studies revealed ROR2 specific CAR-T cells to confer durable responses, significant survival benefits and long-term persistence of CAR-expressing T cells. Overall, there was a trend towards more potent anti-tumor efficacy upon treatment with T cells that expressed the CAR with higher affinity for ROR2, both in vitro and in vivo.
We performed a preclinical safety and toxicology assessment comprising analyses of ROR2 expression in healthy human and murine tissues, cross-reactivity, and adoptive T cell transfer in immunodeficient mice. We found ROR2 expression to be conserved in mice, and low-level expression was detectable in the male and female reproductive system as well as parts of the gastrointestinal tract. CAR-T cells targeting human ROR2 were found to elicit similarly potent reactivity upon recognition of murine ROR2. In vivo analyses showed transient tissue-specific enrichment and activation of ROR2-specific CAR-T cells in organs with high blood circulation, such as lung, liver, or spleen, without evidence for clinical toxicity or tissue damage as determined by histological analyses.
Furthermore, we humanized the CAR binding domain of ROR2-specific CAR-T cells to mitigate the risk of adverse immune reactions and concomitant CAR-T cell rejection. Functional analyses confirmed that humanized CARs retained their specificity and functionality against ROR2-positive tumor cells in vitro.
In summary, we show that ROR2 is a prevalent target in RCC and MM, which can be addressed effectively with ROR2-specific CAR-T cells in preclinical models. Our preliminary toxicity studies suggest a favorable safety profile for ROR2-specific CAR-T cells. These findings support the potential to develop ROR2-specific CAR-T cells clinically to obtain cell products with broad utility.
Plasmonic nanostructures are considered promising candidates for essential components of integrated quantum technologies because of their ability to efficiently localize broad-band electromagnetic fields on the nanoscale. The resulting local near field can be understood as a spatial superposition of spectrally different plasmon-polariton modes due to the spectrally broad optical excitation, and thus can be described as a classical wave packet. Since plasmon polaritons, in turn, can transmit and receive non-classical light states, the exciting question arises to what extent they have to be described as quantum mechanical wave packets, i.e. as a superposition of different quantum states.
But how to probe, characterize and eventually manipulate the quantum state of such plasmon polaritons? Up to now, probing at room temperatures relied completely on analyzing quantum optical properties of the corresponding in-going and out-going far-field photon modes. However, these methods so far only allow a rather indirect investigation of the plasmon-polariton quantum state by means of transfer into photons. Moreover, these indirect methods lack spatial resolution and therefore do not provide on-site access to the plasmon-polariton quantum state. However, since the spectroscopic method of coherent two-dimensional (2D) nanoscopy offers the capability to follow the plasmon-
polariton quantum state both in Hilbert space and in space and time domain a complete characterization of the plasmon polariton is possible.
In this thesis a versatile coherent 2D nanoscopy setup is presented combining spectral tunability and femtosecond time resolution with spatial resolution on the nanometer scale due to the detection of optically excited nonlinear emitted electrons via photoemission electron microscopy (PEEM). Optical excitation by amplitude- and phase-shaped, systematically-modified and interferometric-stable multipulse sequences is realized, and characterized via Fourier-transform spectral interferometry (FTSI). This linear technique enables efficient data acquisition in parallel to a simultaneously performed experiment. The full electric-field reconstruction of every generated multipulse sequence is used to analyze the effect of non-ideal pulse sequences on the two-dimensional spectral data of population-based multidimensional spectroscopy methods like, e.g., the coherent 2D nanoscopy applied in this thesis. Investigation of the spatially-resolved nonlinear electron emission yield from plasmonic gold nanoresonators by coherent 2D nanoscopy requires a quasi-particle treatment of the addressed plasmon-polariton mode and development of a quantum model to adequately describe the plasmon-assisted multi-quantum electron emission from nanostructures. Good agreement between simulated and experimental data enables to connect certain spectral features to superpositions of non-adjacent plasmon-polariton quantum states, i.e, non-adjacent occupation-number states of the underlying quantized, harmonic oscillator, thus direct probing of the plasmon-polariton quantum wave packet at the location of the nanostructure.
This is a necessary step to locally control and manipulate the plasmon-polariton quantum state and thus of general interest for the realization of nanoscale quantum optical devices.
Arrhythmogene Kardiomyopathie (ACM) ist eine genetische Herzerkrankung, die durch Herzinsuffizienz, ventrikuläre Arrhythmien und plötzlichen Herztod gekennzeichnet ist. Mutationen in desmosomalen Proteinen der Zelladhäsion, wie Plakophilin 2 (PKP2) und Plakoglobin (PG), sind die häufigste Ursache der familiären ACM. Wie gestörte Zelladhäsion zum ACM-Phänotyp führt, ist jedoch nur teilweise geklärt. Potentielle Mechanismen sind eine gestörte Kalzium-(Ca2+)-Homöostase, mitochondrialer oxidativer Stress und metabolische Störungen. Ziel dieser Studie ist es, die mitochondriale Energetik und die Ca2+ -Homöostase in kardio-restriktiven PKP2-Knockout-Mäusen (KO) im Alter von 4, 8 und 12 Wochen sowie in PG-Knockout- Mäusen im Alter von 6 Wochen zu untersuchen. Vier Wochen alte PKP2-KO-Mäuse zeigten frühe Anzeichen von ACM, während alle anderen Altersgruppen typische Kennzeichen von ACM rekapitulierten. Kontraktilität, die damit verbundenen Ca2+ - Transienten, der Redoxstatus und das mitochondriale Membranpotenzial (ΔΨm) isolierter Kardiomyozyten wurden mit einem IonOptix-System bei elektrischer und β- adrenerger Stimulation untersucht. Alle desmosomalen KO-Kardiomyozyten zeigten eine verringerte diastolische Sarkomerlänge, was auf eine diastolische Dysfunktion hinwies. In allen PKP2 KO Kardiomyozyten lag außerdem ein erhöhter intrazellulärer Ca2+ -Spiegel vor, während in den PG KO-Kardiomyozyten das intrazellulärer Ca2+ unverändert war. PKP2 KO- und PG KO-Kardiomyozyten wiesen keine Ca2+ - Sensibilisierung der Myofilamente auf. Zur weiteren Bewertung der mitochondrialen Funktion wurde eine hochauflösende Respirometrie in isolierten Herzmitochondrien bei gleichzeitiger Überwachung von ΔΨm in PKP2 KO und PG KO Mäusen durchgeführt, welche in allen Versuchs- und Kontrollgruppen vergleichbar war. Im Verlauf der Versuche blieb der Redoxstatus stabil und es konnte kein Exzess reaktiver Sauerstoffspezies (ROS) festgestellt werden. Daraus konnte gefolgert werden, dass weder PKP2 KO noch PG KO-Mäuse eine beeinträchtigte mitochondriale Atmung aufwiesen. Diese Studie zeigt, dass isolierte PKP2 KO- oder PG KO-Kardiomyozyten EC-Kopplungsdefekte ohne mitochondriale Dysfunktion aufwiesen. Eine mitochondriale Dysfunktion konnte als treibender Faktor für die Progression des ACM- Phänotyps in den vorgestellten Mausmodellen ausgeschlossen werden. Weitere Studien sind erforderlich, um die mitochondriale Funktion im Zusammenhang mit ACM zu entschlüsseln.
Biological systems are in dynamic interaction. Many responses reside in the core concepts of biological systems interplay (competition and cooperation). In infection situation, the competition between a bacterial system and a host is shaped by many stressors at spatial and temporal determinants. Reactive chemical species are universal stressors against all biological systems since they potentially damage the basic requirements of these systems (nucleic acids, proteins, carbohydrates, and lipids). Either produced endogenously or exogenously, reactive chemical species affect the survival of pathogens including the gram-positive
Staphylococcus aureus (S. aureus). Therefore, bacteria developed strategies to overcome the toxicity of reactive species.
S. aureus is a widely found opportunistic pathogen. In its niche, S. aureus is in permanent contact with surrounding microbes and host factors. Deciphering the deterministic factors
in these interactions could facilitate pinpointing novel bacterial targets. Identifying
the aforementioned targets is crucial to develop new strategies not only to kill the pathogenic organisms but also to enhance the normal flora to minimize the pathogenicity and virulence of potential pathogens. Moreover, targeting S. aureus stress response can be used
to overcome bacterial resistance against host-derived factors. In this study, I identify a novel
S. aureus stress response factor against reactive electrophilic, oxygen, and hypochlorite species to better understand its resilience as a pathogen.
Although bacterial stress response is an active research field, gene function is a current bottleneck in characterizing the understudied bacterial strategies to mediate stress conditions. I aimed at understanding the function of a novel protein family integrated
in many defense systems of several biological systems.
In bacteria, fungi, and plants, old yellow enzymes (OYEs) are widely found. Since the first isolation of the yellow flavoprotein, OYEs are used as biocatalysts for decades to reduce activated C=C bonds in α,β-unsaturated carbonyl compounds. The promiscuity
of the enzymatic catalysis is advantageous for industrial applications.
However, the physiological function of OYEs, especially in bacteria, is still puzzling.
Moreover, the relevance of the OYEs in infection conditions remained enigmatic.
Here, I show that there are two groups of OYEs (OYE flavin oxidoreductase, OfrA and OfrB) that are encoded in staphylococci and some firmicutes. OfrA (SAUSA300_0859) is more conserved than OfrB (SAUSA300_0322) in staphylococci and is a part of the staphylococcal core genome.
A reporter system was established to report for ofrA in S. aureus background.
The results showed that ofrA is induced under electrophilic, oxidative, and hypochlorite stress. OfrA protects S. aureus against quinone, methylglyoxal, hydrogen peroxide,
and hypochlorite stress. Additionally, the results provide evidence that OfrA supports
thiol-dependent redox homeostasis. At the host-pathogen interface, OfrA promotes S. aureus fitness in murine macrophage cell line. In whole human blood, OfrA is involved in S. aureus survival indicating a potential clinical relevance to bacteraemia.
In addition, ofrA mutation affects the production of the virulence factor staphyloxanthin via the upper mevalonate pathway. In summary, decoding OfrA function and its proposed mechanism of action in S. aureus shed the light on a conserved stress response within multiple organisms.
Maintaining the balance between CO2 uptake and transpiration is important for plants and depends on tightly controlled turgor changes caused by the activity of various anion and cation channels. These channels are part of signaling cascades triggered, for example, by phytohormones such as ABA (abscisic acid) and JA (jasmonate), both of which act during drought stress in guard cells. In addition, JA is known to be involved in the plant's response to pathogen attack or wounding.
GORK (guard cell outward rectifying K+ channel) is the only known outward rectifying K+ channel in guard cells and therefore responsible for K+ efflux during stomatal closure.
In the course of this work it could be demonstrated by stomatal aperture assays, that GORK is an essential part of JA-induced stomatal closure. This is true for both triggers, leaf wounding as well as direct MeJA (methyl jasmonate) application. Patch clamp experiments on guard cell protoplasts backed this finding by revealing GORK K+ outward currents as a target of JA signaling in guard cells. As cytosolic Ca2+ signals are known to be involved in both ABA as well as JA signaling, the interaction of GORK with Ca2+-dependent kinases was examined consequently. An antagonistic regulation of GORK by
CIPK5-CBL1/9 complexes and ABI2 was identified by DEVC (double electrode voltage clamp) and protein-protein interaction experiments and backed up by in vitro kinase assays. Patch-clamp recordings on guard cell protoplasts of cipk5-2 kinase loss-of-function mutant revealed the importance of CIPK5 for JA-triggered stomatal closure via activation of GORK. The interaction of different CDPKs (Ca2+-dependent protein kinases) with GORK was also investigated.
Besides Ca2+ signaling also ROS (reactive oxygen species) production is essential in ABA and MeJA signaling. In DEVC experiments a reversible effect of ROS on GORK channel activity could be demonstrated, which could be one piece in the explanation of those ROS effects in ABA and MeJA signaling.
In this thesis, a new approach of a qNMR method has been investigated to demonstrate the reliability and importance of this method as an alternative solution for analyzing oil quality parameters, especially in RFO, which has particular characteristics (red color). This study also includes the chemometric evaluation of spectral data for authentication, visual grouping, and prediction of RFO quality based on the degree of unsaturation, FFA value, and unsaturated fatty acid content.
The analytical measurement procedure of NMR spectroscopy begins with optimization of the analytical acquisition parameters, including effect of solvent, effect of sample concentration, selection of appropriate internal standards, determination of T1, and method validation. Furthermore, the results of the method development were interpreted to RFO samples evaluation, which began with determining the assignment of signal spectra for the determination of AV, SV, EV, and IV simultaneously with: the hydrolysis approach and standard addition of palmitic acid.
Background
Complex regional pain syndrome (CRPS) develops after injury and is characterized by disproportionate pain, oedema, and functional loss. CRPS has clinical signs of neuropathy as well as neurogenic inflammation. Here, we asked whether skin biopsies could be used to differentiate the contribution of these two systems to ultimately guide therapy. To this end, the cutaneous sensory system including nerve fibres and the recently described nociceptive Schwann cells as well as the cutaneous immune system were analysed.
Methods
We systematically deep-phenotyped CRPS patients and immunolabelled glabrous skin biopsies from the affected ipsilateral and non-affected contralateral finger of 19 acute (< 12 months) and 6 chronic (> 12 months after trauma) CRPS patients as well as 25 sex- and age-matched healthy controls (HC). Murine foot pads harvested one week after sham or chronic constriction injury were immunolabelled to assess intraepidermal Schwann cells.
Results
Intraepidermal Schwann cells were detected in human skin of the finger—but their density was much lower compared to mice. Acute and chronic CRPS patients suffered from moderate to severe CRPS symptoms and corresponding pain. Most patients had CRPS type I in the warm category. Their cutaneous neuroglial complex was completely unaffected despite sensory plus signs, e.g. allodynia and hyperalgesia. Cutaneous innate sentinel immune cells, e.g. mast cells and Langerhans cells, infiltrated or proliferated ipsilaterally independently of each other—but only in acute CRPS. No additional adaptive immune cells, e.g. T cells and plasma cells, infiltrated the skin.
Conclusions
Diagnostic skin punch biopsies could be used to diagnose individual pathophysiology in a very heterogenous disease like acute CRPS to guide tailored treatment in the future. Since numbers of inflammatory cells and pain did not necessarily correlate, more in-depth analysis of individual patients is necessary.
Emotional dysregulation and its pathways to suicidality in a community-based sample of adolescents
(2024)
Objective
Effective suicide prevention for adolescents is urgently needed but difficult, as suicide models lack a focus on age-specific influencing factors such as emotional dysregulation. Moreover, examined predictors often do not specifically consider the contribution to the severity of suicidality.
To determine which adolescents are at high risk of more severe suicidality, we examined the association between emotional dysregulation and severity of suicidality directly as well as indirectly via depressiveness and nonsuicidal self-injury.
Method
Adolescents from 18 high schools in Bavaria were included in this cross-sectional and questionnaire-based study as part of a larger prevention study. Data were collected between November 2021 and March 2022 and were analyzed from January 2023 to April 2023.
Students in the 6th or 7th grade of high school (11–14 years) were eligible to participate. A total of 2350 adolescents were surveyed and data from 2117 students were used for the analyses after excluding incomplete data sets. Our main outcome variable was severity of suicidality (Paykel Suicide Scale, PSS). Additionally, we assessed emotional dysregulation (Difficulties in Emotion Regulation Scale, DERS-SF), depressiveness (Patient Health Questionnaire, PHQ-9) and nonsuicidal self-injury (Deliberate Self-Harm Inventory, DSHI).
Results
In total, 2117 adolescents (51.6% female; mean age, 12.31 years [standard deviation: 0.67]) were included in the structural equation model (SEM). Due to a clear gender-specific influence, the model was calculated separately for male and female adolescents. For male adolescents, there was a significant indirect association between emotional dysregulation and severity of suicidality, mediated by depressiveness (β = 0.15, SE = .03, p = .008). For female adolescents, there was a significant direct path from emotional dysregulation to severity of suicidality and also indirect paths via depressiveness (β = 0.12, SE = .05, p = 0.02) and NSSI (β = 0.18, SE = .04, p < .001).
Conclusions
Our results suggest that gender-related risk markers in 11–14-year-olds need to be included in future suicide models to increase their predictive power. According to our findings, early detection and prevention interventions based on emotion regulation skills might be enhanced by including gender-specific adjustments for the co-occurrence of emotional dysregulation, depressiveness, and nonsuicidal self-injury in girls and the co-occurrence of emotional dysregulation and depressiveness in boys.
Humans actively interact with the world through a wide range of body movements. To understand human cognition in its natural state, we need to incorporate ecologically relevant body movement into our account. One fundamental body movement during daily life is natural walking. Despite its ubiquity, the impact of natural walking on brain activity and cognition has remained a realm underexplored.
In electrophysiology, previous studies have shown a robust reduction of ongoing alpha power in the parieto-occipital cortex during body movements. However, what causes the reduction of ongoing alpha, namely whether this is due to body movement or prevalent sensory input changes, was unknown. To clarify this, study 1 was performed to test if the alpha reduction is dependent on visual input. I compared the resting state alpha power during natural walking and standing, in both light and darkness. The results showed that natural walking led to decreased alpha activity over the occipital cortex compared to standing, regardless of the lighting condition. This suggests that the movement-induced modulation of occipital alpha activity is not driven by visual input changes during walking. I argue that the observed alpha power reduction reflects a change in the state of the subject based on disinhibition induced by walking. Accordingly, natural walking might enhance visual processing and other cognitive processes that involve occipital cortical activity.
I first tested this hypothesis in vision. Study 2 was performed to examine the possible effects of natural walking across visual processing stages by assessing various neural markers during different movement states. The findings revealed an amplified early visual response, while a later visual response remain unaffected. A follow-up study 3 replicated the walking-induced enhancement of the early visual evoked potential and showed that the enhancement was dependent on specific stimulus-related parameters (eccentricity, laterality, distractor presence). Importantly, the results provided evidence that the enhanced early visual responses are indeed linked to the modulation of ongoing occipital alpha power. Walking also modulated the stimulus-induced alpha power. Specifically, it showed that when the target appeared in the fovea area without a distractor, walking exhibited a significantly reduced modulation of alpha power, and showed the largest difference to standing condition. This effect of eccentricity indicates that during later visual processing stages, the visual input in the fovea area is less processed than in peripheral areas while walking.
The two visual studies showed that walking leads to an enhancement in temporally early visual processes which can be predicted by the walking-induced change in ongoing alpha oscillation likely marking disinhibition. However, while walking affects neural markers of early sensory processes, it does not necessarily lead to a change in the behavioural outcome of a sensory task. The two visual studies suggested that the behavioural outcome seems to be mainly based on later processing stages.
To test the effects of walking outside the visual domain, I turned to audition in study 4. I investigated the influence of walking in a particular path vs. simply stepping on auditory processing. Specifically, the study tested whether enhanced processing due to natural walking can be found in primary auditory brain activity and whether the processing preferences are dependent on the walking path. In addition, I tested whether the changed spatial processing that was reported in previous visual studies can be seen in the auditory domain. The results showed enhanced sensory processing due to walking in the auditory domain, which was again linked to the modulation of occipital alpha oscillation. The auditory processing was further dependent on the walking path. Additionally, enhanced peripheral sensory processing, as found in vision, was also present in audition.
The findings outside vision supported the idea of natural walking affecting cognition in a rather general way. Therefore in my study 5, I examined the effect of natural walking on higher cognitive processing, namely divergent thinking, and its correlation with the modulation of ongoing alpha oscillation. I analyzed alpha oscillations and behavioural performance during restricted and unrestricted movement conditions while subjects completed a Guilford's alternate uses test. The results showed that natural walking, as well as missing body restriction, reduces the occipital alpha ongoing power independent of the task phase which goes along with higher test scores. The occipital alpha power reduction can therefore be an indicator of a changed state that allows improved higher cognitive processes.
In summary, the research presented in this thesis highlights that natural walking can change different processes in the visual and auditory domain as well as higher cognitive processes. The effect can be attributed to the movement of natural walking itself rather than to changes in sensory input during walking. The results further indicate that the walking-induced modulation of ongoing occipital alpha oscillations drives the cognitive effects. We therefore suggest that walking changes the inhibitory state which can influence awareness and attention. Such a mechanism could facilitate an adaptive enhancement in cognitive processes and thereby optimize movement-related behaviour such as navigation.
Compared to other countries, China was particularly early in developing a comprehensive set of policies to promote electric mobility (e-mobility). The aim of this study is to examine how China’s e-mobility development – through changes in formal institutions as well as market forces – has affected German passenger car manufacturers and their competitive environment and positions. The study is guided by two strands of research: new institutional economics and strategic management literature. A holistic multiple-case design is used to analyze five German case study firms. Qualitative interview data are collected through interviews and analyzed using a thematic analysis. The results show that the electric transformation in China has been shaped by changes in formal institutions at the macro, meso, and micro levels. Interestingly, the case study firms were affected not only by changes in China’s formal institutions but also by disparities between institutions in China and Europe. Furthermore, the data suggest that German car manufacturers are facing an increasingly competitive environment in China: at least four forces in Porter’s five-forces model seem to have intensified in recent years. The extent to which the case study firms have been affected by these developments may depend on the industry segments in which they are positioned. However, it can be argued that the electric transition has blurred the lines between traditional segments of the car industry to some extent. The interview data do not provide evidence that any of the German car brands have substantially changed their positioning, but they do suggest that some of the case study companies did not have an adequate offering for the Chinese market at the time of the interviews. In addition, the study finds that China’s transition to e-mobility has led to changes in various parts of the German automakers’ value chains, including production, sales, marketing, services, research and development, and procurement. Whether these changes will ultimately result in competitive advantage, parity, or disadvantage remains to be seen.
Introduction.
Mobile health (mHealth) integrates mobile devices into healthcare, enabling remote monitoring, data collection, and personalized interventions. Machine Learning (ML), a subfield of Artificial Intelligence (AI), can use mHealth data to confirm or extend domain knowledge by finding associations within the data, i.e., with the goal of improving healthcare decisions. In this work, two data collection techniques were used for mHealth data fed into ML systems: Mobile Crowdsensing (MCS), which is a collaborative data gathering approach, and Ecological Momentary Assessments (EMA), which capture real-time individual experiences within the individual’s common environments using questionnaires and sensors. We collected EMA and MCS data on tinnitus and COVID-19. About 15 % of the world’s population suffers from tinnitus.
Materials & Methods.
This thesis investigates the challenges of ML systems when using MCS and EMA data. It asks: How can ML confirm or broad domain knowledge? Domain knowledge refers to expertise and understanding in a specific field, gained through experience and education. Are ML systems always superior to simple heuristics and if yes, how can one reach explainable AI (XAI) in the presence of mHealth data? An XAI method enables a human to understand why a model makes certain predictions. Finally, which guidelines can be beneficial for the use of ML within the mHealth domain? In tinnitus research, ML discerns gender, temperature, and season-related variations among patients. In the realm of COVID-19, we collaboratively designed a COVID-19 check app for public education, incorporating EMA data to offer informative feedback on COVID-19-related matters. This thesis uses seven EMA datasets with more than 250,000 assessments. Our analyses revealed a set of challenges: App user over-representation, time gaps, identity ambiguity, and operating system specific rounding errors, among others. Our systematic review of 450 medical studies assessed prior utilization of XAI methods.
Results.
ML models predict gender and tinnitus perception, validating gender-linked tinnitus disparities. Using season and temperature to predict tinnitus shows the association of these variables with tinnitus. Multiple assessments of one app user can constitute a group. Neglecting these groups in data sets leads to model overfitting. In select instances, heuristics outperform ML models, highlighting the need for domain expert consultation to unveil hidden groups or find simple heuristics.
Conclusion.
This thesis suggests guidelines for mHealth related data analyses and improves estimates for ML performance. Close communication with medical domain experts to identify latent user subsets and incremental benefits of ML is essential.
Background
Iron deficiency (ID) is the leading cause of anemia worldwide. The prevalence of preoperative ID ranges from 23 to 33%. Preoperative anemia is associated with worse outcomes, making it important to diagnose and treat ID before elective surgery. Several studies indicated the effectiveness of intravenous iron supplementation in iron deficiency with or without anemia (ID(A)). However, it remains challenging to establish reliable evidence due to heterogeneity in utilized study outcomes. The development of a core outcome set (COS) can help to reduce this heterogeneity by proposing a minimal set of meaningful and standardized outcomes. The aim of our systematic review was to identify and assess outcomes reported in randomized controlled trials (RCTs) and observational studies investigating iron supplementation in iron-deficient patients with or without anemia.
Methods
We searched MEDLINE, CENTRAL, and ClinicalTrials.gov systematically from 2000 to April 1, 2022. RCTs and observational studies investigating iron supplementation in patients with a preoperative diagnosis of ID(A), were included. Study characteristics and reported outcomes were extracted. Outcomes were categorized according to an established outcome taxonomy. Quality of outcome reporting was assessed with a pre-specified tool. Reported clinically relevant differences for sample size calculation were extracted.
Results
Out of 2898 records, 346 underwent full-text screening and 13 studies (five RCTs, eight observational studies) with sufficient diagnostic inclusion criteria for iron deficiency with or without anemia (ID(A)) were eligible. It is noteworthy to mention that 49 studies were excluded due to no confirmed diagnosis of ID(A). Overall, 111 outcomes were structured into five core areas including nine domains. Most studies (92%) reported outcomes within the ‘blood and lymphatic system’ domain, followed by “adverse event” (77%) and “need for further resources” (77%). All of the latter reported on the need for blood transfusion. Reported outcomes were heterogeneous in measures and timing. Merely, two (33%) of six prospective studies were registered prospectively of which one (17%) showed no signs of selective outcome reporting.
Conclusion
This systematic review comprehensively depicts the heterogeneity of reported outcomes in studies investigating iron supplementation in ID(A) patients regarding exact definitions and timing. Our analysis provides a systematic base for consenting to a minimal COS.
Systematic review registration
PROSPERO CRD42020214247
Angesichts aktueller und zurückliegender Migrations- und Fluchtprozesse in Deutschland kommen Jugendliche der Residenzgesellschaft in verschiedenen Bereichen ihres Lebens mit Menschen mit Flucht- oder Migrationserfahrung in Kontakt, woraus sich Chancen und Entwicklungspotenziale, aber auch Herausforderungen ergeben. Beispielsweise kann vermehrter interkultureller Kontakt auf individueller Ebene zur Weiterentwicklung von Toleranz und Empathie führen. Jedoch können Jugendliche der Residenzgesellschaft auf vermehrte Zuwanderung auch mit einem Gefühl der Unsicherheit und einer ablehnenden Haltung gegenüber Menschen mit Flucht- oder Migrationserfahrung reagieren. Diese Reaktionen können durch einseitige oder negative Medienberichte zum Themenkomplex Flucht und Migration verstärkt werden. Um Chancen und Entwicklungspotenziale ausschöpfen sowie Herausforderungen im Kontext von Flucht und Migration bewältigen zu können, müssen Jugendliche in der Entwicklung interkultureller Kompetenz gefördert werden. Interkulturelle Kompetenz ist eine wesentliche Voraussetzung für das Zusammenleben in einer pluralistischen Gesellschaft und daher ein bedeutsames Bildungs- und Erziehungsziel für Schule und Unterricht.
Die Zielstellung der vorliegenden Forschungsarbeit ist demnach die praxis- und theorieorientierte Entwicklung und Evaluation eines Unterrichtskonzepts zur Förderung interkultureller Kompetenz unter Verwendung digitaler Medienangebote und Gestaltung medialer Beiträge.
Hinsichtlich theoretischer Grundlagen zu interkultureller Kompetenz wird vor dem Hintergrund eines an Offenheit, Prozesshaftigkeit und Heterogenität orientierten Kulturbegriffs Interkulturalität als sozialer Prozess verstanden, in dem sich Personen unterschiedlicher kultureller bzw. kollektiver Zugehörigkeiten begegnen, miteinander interagieren und kommunizieren. Interkulturelle Kompetenz setzt sich aus Wissen (kognitive Dimension), Einstellungen (affektive Dimension) sowie Verhaltensweisen (behaviorale Dimension) zusammen und es wird angenommen, dass diese erlernt und gefördert werden kann. Vorgehensweisen zur Entwicklung interkultureller Kompetenz sollten die kognitive, affektive und behaviorale Dimension interkultureller Kompetenz adressieren, die Reflexion authentischer, kritischer Überschneidungssituationen einbeziehen sowie realweltliche, interkulturelle Begegnungen als Lerngelegenheiten aufgreifen.
Bezüglich theoretischer Grundlagen zum Lehren und Lernen mit Medien stellt vor dem Hintergrund verschiedener Ansätze zum Lehren und Lernen mit Medien die handlungs- und entwicklungsorientierte Didaktik eine bedeutsame Grundlage für die vorliegende Forschungsarbeit dar. Sie wird bezüglich der Prinzipien der Situations-, Bedürfnis-, Erfahrungs- und Entwicklungsorientierung, der Bedeutsamkeit komplexer, lernprozessanregender Aufgabenstellungen und einer idealtypischen Strukturierung von Unterricht mit theoretischen Grundlagen interkultureller Kompetenz und Vorgehensweisen zu ihrer Förderung in Beziehung gesetzt.
Hinsichtlich des forschungsmethodischen Vorgehens wird auf Basis einer Gegenüberstellung verschiedener Ansätze der gestaltungsorientierten Bildungsforschung der Ansatz einer praxis- und theorieorientierten Entwicklung und Evaluation von Konzepten unterrichtlichen Handelns für die vorliegende Forschungsarbeit begründet ausgewählt und seine Umsetzung erläutert.
Im Rahmen der ersten Studie wird auf der Basis theoretischer und empirischer Grundlagen interkultureller Kompetenz und didaktischer Zugänge ein pädagogisches Konzept zur Förderung interkultureller Kompetenz von Schülerinnen und Schülern der Sekundarstufe I unter Verwendung digitaler Medien entwickelt und für eine achte Klasse am Gymnasium konkretisiert. Das Konzept wird hinsichtlich seiner Zielerreichung sowie auftretender Nebenwirkungen unter Einsatz von Mixed Methods evaluiert. Die Ergebnisse weisen unter anderem darauf hin, dass das entwickelte Unterrichtskonzept zur Förderung interkultureller Kompetenz der Schülerinnen und Schüler beigetragen hat.
Die zweite Studie stellt eine ergänzende qualitative Studie dar, mit dem Ziel, die gemeinsame Mediengestaltung in Zusammenarbeit von Lernenden mit und ohne Flucht- bzw. Migrationserfahrung als bedeutsame Lernaktivität des Unterrichtskonzepts vertiefend zu untersuchen und Vorgehensweisen des kollaborativen Gestaltungsprozesses, die aus der Perspektive der Schülerinnen und Schüler wichtig sind, zu identifizieren. Hierzu werden die subjektiven Sichtweisen der Gymnasiastinnen und Gymnasiasten auf die Gestaltung medialer Beiträge in interkultureller Begegnung unter Bezugnahme auf interkulturelle Sensibilität in Fokusgruppen erhoben und qualitativ-inhaltsanalytisch ausgewertet. Die Ergebnisse der qualitativen Inhaltsanalyse zeigen, dass im Rahmen der Mediengestaltung verschiedene Komponenten interkultureller Sensibilität angesprochen wurden. Beispielsweise geben einige Gymnasiastinnen und Gymnasiasten an, dass ihnen sowohl die Zusammenarbeit mit den Mittelschülerinnen und -schülern als auch die gemeinsame Mediengestaltung Freude bereitete.
In der dritten Studie werden die von den Schülerinnen und Schülern gestalteten Medienbeiträge aus interkulturell-kommunikativer und medienbezogener Perspektive vertiefend analysiert. Die Auswertung erfolgt durch qualitative Inhaltsanalysen hinsichtlich wesentlicher Aspekte der Kommunikationssituation, der Medienmerkmale sowie Bezugspunkten zur behavioralen Dimension interkultureller Kompetenz. Aus den Ergebnissen der Videoanalysen geht unter anderem hervor, dass die interkulturellen Begegnungssituationen, die im Rahmen der Beiträge dargestellt werden, aus kommunikationstheoretischer Perspektive komplex und vielschichtig sind.
Nach einer abschließenden kritischen Methodenreflexion werden Ergebnisse der Studien zusammengeführt und interpretiert. Beispielsweise geht aus der Zusammenführung der Ergebnisse aus der ersten und der zweiten Studie hervor, dass sich zwischen Pre- und Post-Test eine statistisch signifikante Steigerung des Mittelwertes der Komponente Aufmerksamkeit während der interkulturellen Interaktion ergibt, was unter Berücksichtigung der Resultate aus den Fokusgruppen als gesteigertes Interesse der Probandinnen und Probanden an den Schülerinnen und Schülern der Mittelschulklasse im Laufe der gemeinsamen Videogestaltung gedeutet werden kann. Die vergleichende Betrachtung von Ergebnissen aus der ersten und der dritten Studie zeigt, dass mit einer Steigerung des Summenscores der behavioralen Dimension interkultureller Kompetenz Bezüge zu verschiedenen Komponenten der behavioralen Dimension im Rahmen der gestalteten Videos in Verbindung stehen.
Hinsichtlich der Konsequenzen für zukünftige Forschung wird abschließend auf die Notwendigkeit der Entwicklung von Verfahren zur Erfassung interkultureller Kompetenz von Jugendlichen mit unzureichenden Deutschkenntnissen verwiesen. Bezüglich der Praxis in Schule und Unterricht ist die Förderung interkultureller Kompetenz unter Verwendung und Gestaltung digitaler Medienangebote bzw. -beiträge als schulische Querschnittsaufgabe aller Jahrgangsstufen, Fächer und Schulformen wahrzunehmen. Insgesamt leistet die vorliegende Forschungsarbeit damit einen Beitrag zur Verknüpfung der Förderung interkultureller Kompetenz mit der interkulturell-kooperativen Gestaltung medialer Beiträge.
This doctoral thesis investigates magneto-optical properties of mercury telluride layers grown tensile strained on cadmium telluride substrates. Here, layer thicknesses start above the usual quantum well thickness of about 20 nm and have a upper boundary around 100 nm due to lattice relaxation effects. This kind of layer system has been attributed to the material class of three-dimensional topological insulators in numerous publications. This class stands out due to intrinsic boundary states which cross the energetic band gap of the layer's bulk.
In order to investigate the band structure properties in a narrow region around the Fermi edge, including possible boundary states, the method of highly precise time-domain Terahertz polarimetry is used. In the beginning, the state of the art of Teraherz technology at the start of this project is discussed, moving on to a detailed description and characterization of the self-built measurement setup. Typical standard deviation of a polarization rotation or ellipticity measurement are on the order of 10 to 100 millidegrees, according to the transmission strength through investigated samples. A range of polarization spectra, depending on external magnetic fields up to 10 Tesla, can be extracted from the time-domain signal via Fourier transformation.
The identification of the actual band structure is done by modeling possible band structures by means of the envelope function approximation within the framework of the k·p method. First the bands are calculated based on well-established model parameters and from them the possible optical transitions and expected ellipticity spectra, all depending on external magnetic fields and the layer's charge carrier concentration. By comparing expected with measured spectra, the validity of k·p models with varying depths of detail is analyzed throughout this thesis. The rich information encoded in the ellipitcity spectra delivers key information for the attribution of single optical transitions, which are not part of pure absorption spectroscopy. For example, the sign of the ellipticity signals is linked to the mix of Landau levels which contribute to an optical transition, which shows direct evidence for bulk inversion asymmetry effects in the measured spectra.
Throughout the thesis, the results are compared repeatedly with existing publications on the topic. It is shown that the models used there are often insufficient or, in worst case, plainly incorrect. Wherever meaningful and possible without greater detours, the differences to the conclusions that can be drawn from the k·p model are discussed.
The analysis ends with a detailed look on remaining differences between model and measurement. It contains the quality of model parameters as well as different approaches to integrate electrostatic potentials that exist in the structures into the model.
An outlook on possible future developments of the mercury cadmium telluride layer systems, as well as the application of the methods shown here onto further research questions concludes the thesis.
Neisseria meningitidis (the meningococcus) is one of the major causes of bacterial meningitis, a life-threatening inflammation of the meninges. Traversal of the meningeal blood-cerebrospinal fluid barrier (mBCSFB), which is composed of highly specialized brain endothelial cells (BECs), and subsequent interaction with leptomeningeal cells (LMCs) are critical for disease progression. Due to the human-exclusive tropism of N. meningitidis, research on this complex host-pathogen interaction is mostly limited to in vitro studies. Previous studies have primarily used peripheral or immortalized BECs alone, which do not retain relevant barrier phenotypes in culture. To study meningococcal interaction with the mBCSFB in a physiologically more accurate context, BEC-LMC co-culture models were developed in this project using BEC-like cells derived from induced pluripotent stem cells (iBECs) or hCMEC/D3 cells in combination with LMCs derived from tumor biopsies.
Distinct BEC and LMC layers as well as characteristic expression of cellular markers were observed using transmission electron microscopy (TEM) and immunofluorescence staining. Clear junctional expression of brain endothelial tight and adherens junction proteins was detected in the iBEC layer. LMC co-culture increased iBEC barrier tightness and stability over a period of seven days, as determined by sodium fluorescein (NaF) permeability and transendothelial electrical resistance (TEER). Infection experiments demonstrated comparable meningococcal adhesion and invasion of the BEC layer in all models tested, consistent with previously published data. While only few bacteria crossed the iBEC-LMC barrier initially, transmigration rates increased substantially over 24 hours, despite constant high TEER. After 24 hours of infection, deterioration of the barrier properties was observed including loss of TEER and altered expression of tight and adherens junction components. Reduced mRNA levels of ZO-1, claudin-5, and VE-cadherin were detected in BECs from all models. qPCR and siRNA knockdown data suggested that transcriptional downregulation of these genes was potentially but not solely mediated by Snail1. Immunofluorescence staining showed reduced junctional coverage of occludin, indicating N. meningitidis-induced post-transcriptional modulation of this protein, as previous studies have suggested. Together, these results suggest a potential combination of transcellular and paracellular meningococcal traversal of the mBCSFB, with the more accessible paracellular route becoming available upon barrier disruption after prolonged N. meningitidis infection. Finally, N. meningitidis induced cellular expression of pro-inflammatory cytokines and chemokines such as IL-8 in all mBCSFB models. Overall, the work described in this thesis highlights the usefulness of advanced in vitro models of the mBCSFB that mimic native physiology and exhibit relevant barrier properties to study infection with meningeal pathogens such as N. meningitidis.
Integrative, three-dimensional \(in\) \(silico\) modeling of gas exchange in the human alveolus
(2024)
The lung plays a vital role by exchanging respiratory gases. At the core of this gas exchange is a simple yet crucial passive diffusion process occurring within the alveoli. These balloon-like structures, connected to the peripheral airways, are surrounded by a dense network
of small capillaries. Here, inhaled air comes into close proximity with deoxygenated blood coming from the heart, enabling the exchange of oxygen and carbon dioxide across their concentration gradients.
The efficiency of gas exchange can be measured through indicators such as the diffusion capacity of the lung for oxygen and the reaction half-time. A notable discrepancy exists in humans between physiological estimates of diffusion capacity and the theoretical maximum capacity under optimal structural conditions (morphological estimate). This discrepancy is influenced by a range of interrelated factors, including structural elements like the surface area and thickness of the diffusion barrier, as well as physiological factors such as blood flow dynamics. To unravel the different roles of these factors, we investigated how morphological and physiological properties of the human alveolar micro-environment collectively and individually influence the process of gas exchange. To this end, we developed an integrative in silico approach combining 3D morphological modeling and simulation of blood flow and of oxygen transport.
At the core of our approach lies the simulation software Alvin, serving as an interactive platform for the underlying mathematical model of oxygen transport within the alveolus. Developed by integrating and expanding existing mathematical models, our spatio-temporal model produces results in agreement with experimental data. Alvin allows for real-time parameter adjustments and the execution of multiple simultaneous simulation instances and provides detailed quantitative feedback, offering an immersive exploration of the simulated gas exchange process. The morphological and physiological parameters at play were further investigated with a focus on the microvasculature. By compiling a stereological database from the literature and 3D geometric modeling, we created a sheet-flow model as a realistic representation of the morphology of the human alveolar capillary network. Blood flow was simulated using computational fluid dynamics. Our findings were in line with previous estimations and highlighted the crucial role of viscosity models in predicting pressure drop across the microvasculature. Furthermore, we showcased how our approach can be harnessed to explore structural details, such as the connectivity of the alveolar capillary network with the vascular tree, using blood flow indices. It is important to emphasize that
so far we have relied on different data sources and that experimental validation is needed to move forward.
Integration of our findings into Alvin allowed quantification of the simulated gas exchange process through the diffusion capacity for oxygen and reaction half-time. In addition to evaluating the collective influences of the morphological and physiological properties, our interactive software facilitates the assessment of individual parameter value changes. Exploring blood volume and surface area available for gas exchange revealed linear correlations with diffusion capacity. The blood flow velocity had a positive, non-linear effect on diffusion capacity. The reaction half-time confirmed that under normal conditions, the gas exchange process is not diffusion-limited. Collectively, our alveolar model yielded a diffusion capacity value that fell in the middle of previous physiological and morphological estimates, implying that alveolar-level phenomena contribute to 50% of the diffusion capacity limitations that occur in vivo.
In summary, our integrative in silico approach disentangles various structural and functional influences on alveolar gas exchange, complementing traditional investigations in respiratory
research. We further showcase its utility in teaching and the interpretation of published data. To advance our understanding, future work should prioritize obtaining a cohesive experimental data set and identifying an appropriate viscosity model for blood flow simulations.
Immunofluorescence is a common method to localise proteins within their cellular context via fluorophore labelled antibodies and for some applications without alternative. However, some protein targets evade detection due to low protein abundance or accessibility issues. In addition, some imaging methods require a massive reduction in antigen density thus impeding detection of even medium-abundant proteins.Here, we show that the fusion of the target protein to TurboID, a biotin ligase labelling lysine residues in close proximity, and subsequent detection of biotinylation by fluorescent streptavidin offers an “all in one” solution to the above-mentioned restrictions. For a wide range of target proteins tested, the streptavidin signal was significantly stronger than an antibody signal, markedly improving the imaging sensitivity in expansion microscopy and correlative light and electron microscopy, with no loss in resolution. Importantly, proteins within phase-separated regions, such as the central channel of the nuclear pores, the nucleolus or RNA granules, were readily detected with streptavidin, while most antibodies fail to label proteins in these environments. When TurboID is used in tandem with an HA epitope tag, co-probing with streptavidin and anti-HA can be used to map antibody-accessibility to certain cellular regions. As a proof of principle, we mapped antibody access to all trypanosome nuclear pore proteins (NUPs) and found restricted antibody labelling of all FG NUPs of the central channel that are known to be phase-separated, while most non-FG Nups could be labelled. Lastly, we show that streptavidin imaging can resolve dynamic, temporally and spatially distinct sub-complexes and, in specific cases, reveal a history of dynamic protein interaction.In conclusion, streptavidin imaging has major advantages for the detection of lowly abundant or inaccessible proteins and in addition, can provide information on protein interactions and biophysical environment.
Gegenstand der Arbeit ist eine internationale Untersuchung der urheberrechtlichen Schranke der sogenannten Panoramafreiheit oder Freiheit des Straßenbildes. Durch diese Schranke wird das Urheberrecht an Werken im öffentlichen Raum eingeschränkt. Auf unionsrechtlicher Ebene sieht die Richtlinie 2001/29/EG in Art. 5 Abs. 3 lit. h eine fakultative Schranke zugunsten der Freiheit des Straßenbildes vor. Diese fakultative Schranke wurde von den Mitgliedstaaten der Europäischen Union sehr unterschiedlich in nationales Recht umgesetzt. Nach § 59 des deutschen Urheberrechtsgesetzes ist es zulässig, Werke, die sich bleibend an öffentlichen Wegen, Straßen oder Plätzen befinden, mit Mitteln der Malerei oder Graphik, durch Lichtbild oder durch Film zu vervielfältigen, zu verbreiten und öffentlich wiederzugeben. Daneben gibt es auch Mitgliedstaaten, die die Schranke nicht oder nur eingeschränkt in nationales Recht umgesetzt haben. Auch Länder außerhalb der Europäischen Union sehen in nationalen Urheberrechtsgesetzen Regelungen zugunsten der Freiheit des Straßenbildes vor. Daher wurden im Rahmen der Arbeit verschiedene nationale Regelungen zur Panoramafreiheit gegenübergestellt, um die wesentlichen Unterschiede zwischen den Vorschriften zu untersuchen und herauszuarbeiten.