Curve interactions in R^2: An analytical and stochastical approach

In the last few years a lot of work has been done in the investigation of Brownian motion with point interaction(s) in one and higher dimensions. Roughly speaking a Brownian motion with point interaction is nothing else than a Brownian motion whose generator is disturbed by a measure supported in just one point. The purpose of the present work is the introducing of curve interactions of the two dimensional Brownian motion for a closed curve $\mathcal{C}$. We will understand a curve interaction as a self-adjoint extension of the restriction of the Laplacian to the set of infinitely often continuously differentiable functions with compact support in $\mathbb{R}^{2}$ which are constantly 0 at the closed curve. We will give a full description of all these self-adjoint extensions. In the second chapter we will prove a generalization of Tanaka's formula to $\mathbb{R}^{2}$. We define $g$ to be a so-called harmonic single layer with continuous layer function $\eta$ in $\mathbb{R}^{2}$. For such a function $g$ we prove \begin{align} g\left(B_{t}\right)=g\left(B_{0}\right)+\int\limits_{0}^{t}{\nabla g\left(B_{s}\right)\mathrm{d}B_{s}}+\int\limits_{0}^{t}\eta\left(B_{s}\right)\mathrm{d}L\left(s,\mathcal{C}\right) \end{align} where $B_{t}$ is just the usual Brownian motion in $\mathbb{R}^{2}$ and $L\left(t,\mathcal{C}\right)$ is the connected unique local time process of $B_{t}$ on the closed curve $\mathcal{C}$. We will use the generalized Tanaka formula in the following chapter to construct classes of processes related to curve interactions. In a first step we get the generalization of point interactions in a second step we get processes which behaves like a Brownian motion in the complement of $\mathcal{C}$ and has an additional movement along the curve in the time- scale of $L\left(t,\mathcal{C}\right)$. Such processes do not exist in the one point case since there we cannot move when the Brownian motion is in the point. By establishing an approximation of a curve interaction by operators of the form Laplacian $+V_{n}$ with "nice" potentials $V_{n}$ we are able to deduce the existence of superprocesses related to curve interactions. The last step is to give an approximation of these superprocesses by a sytem of branching particles. This approximation gives a better understanding of the related mass creation

Chemical Biology Applications of Photoresponsive DNA-Binding Agents

This thesis presents the synthesis of novel photoresponsive DNA-binding agents as well as their application for both visualization and control of biological processes. In addition, the implementation of an innovative course to transfer the interdisciplinary research culture of chemical biology to education is reported. This cumulative dissertation is mainly composed of four chapters, each of them dealing with either published or submitted articles under revision. An introduction, motivation and outlook are included, too. The first article is published in Angewandte Chemie International Edition, and describes the development of a new far-red fluorescent DNA binder, 6-TramTO-3, as an alternative chemical tool to the green fluorescent protein (GFP) for interaction studies of live multidrug-resistant pathogens and host cells. Thus, the derivatization of thiazole orange (TO) resulted in a new cyanine dye, 6-TramTO-3, whose spectroscopic properties were analyzed. DNA binding analysis by UV-vis, fluorescence and CD spectroscopy was performed to study the interaction mode upon addition to DNA. Initially, fluorescence confocal microscopy, FACS and growth curve analysis with live E. coli displayed an efficient staining of more than 90% and no effect on the bacterial viability. Importantly, 6-TramTO-3 overcomes common limitations of other frequently used fluorophores like ethidium bromide, carboxyfluorescein succinimidyl ester and SyTO-9, such as low staining efficiency and cytotoxicity without genetic manipulation. Encouraged by these unique properties, we tested 6-TramTO-3 with antibiotic-sensitive and multidrug-resistant Klebsiella pneumoniae strains. 6-TramTO-3 conferred both strains a highly specific red-fluorescent shift with 91% and 87% in the 652-671 nm red2 channel without observable cytotoxic effects. Next, we performed phagocytosis assays with human macrophages, which revealed a different strain behavior for the first time. Besides the publication, an European patent was filed (18174086.1 – 1011) and numerous collaborations with universities, research institutes and companies were initiated to apply 6-TramTO-3 in different contexts. The second article is published in Organic & Biomolecular Chemistry, and presents ortho-tetra-fluoroazobenzene derivatives as DNA intercalators for photocontrol of DNA and nucleosome binding upon visible-light irradiation. Its use is less harmful to biological systems and therefore, preferred over UV-light, which is needed for the most known nucleic acid targeting photoswitchable systems. Thus, the introduction of such moiety in the backbone of the minor groove binder netropsin added dynamic control and changed the recognition mode. UV-vis, HPLC and NMR analysis demonstrated the photoisomerization of the new compounds by visible light. DNA-binding analysis conducted by UV-vis, fluorescence and CD spectroscopy revealed an intercalating binding mode in the low nM-region with differences between isomers. Finally, the use of the new derivative as a light-controllable nucleosome binder was explored. The different binding affinities observed on free DNA were corroborated for the nucleosomal DNA. Interestingly, electromobility shift assays and dynamic light scattering experiments proved that when the compound is in its trans-form, it intercalated into the nucleosomal DNA, induced distortion, which further led to disruption of the nucleosomes. These findings will help to introduce photochemical control to pave the way to altering nucleosome-based processes by light. The third chapter of this thesis is a submitted manuscript to the journal Organic Letters under revision and deals with a novel synthetic approach to access pyrrole-imidazole (Py-Im) DNA binding polyamides based on 4-methyltrityl (Mtt) solid-phase peptide synthesis (SPPS). Commonly Py-Im polyamide hairpins are synthesized by Boc- and Fmoc- SPPS. New Mtt-protected pyrrole and imidazole building blocks were synthesized with higher yields than the Boc- and Fmoc-analogues. Their implementation could successfully be shown by the synthesis and study of a DNA-binding polyamide applying all Mtt-building blocks. Our methodology is orthogonal to Fmoc and will allow the implementation of base labile compounds and other sensitive groups in Py-Im polyamide chemistry affording novel polyamide conjugates. In a further attempt, it was already possible to use the new building blocks for the introduction of a photoswitchable compound into the polyamide-hairpin backbone, which will access the introduction of dynamic and spatial control in the level of sequence specific DNA binding in biological assays. The fourth chapter is a submitted manuscript to the Journal of Chemical Education under replied revision, in which a novel course for master students in chemistry and biology is introduced to fill the missing gap between cutting-edge interdisciplinary research and education of future scientists. In other words, our course aimed at bringing the authentic “big picture” of science by the combination of lectures, a discovery-based research laboratory and science communication. The students experienced the advantages of collaborative work, wrote a short article and were guided in the design and defense of their own research proposals in chemical biology. Evaluation of the course clearly proved that the course fosters cooperative research relationships between biology and chemistry students, provides a unique and genuine research experience and increased the students’ interest in interdisciplinary approaches and collaborative work. The course and assessment material was accessible to inspire other interdisciplinary field

Global DNA hypomethylation prevents consolidation of differentiation programs and allows reversion to the embryonic stem cell state.

DNA methylation patterns change dynamically during mammalian development and lineage specification, yet scarce information is available about how DNA methylation affects gene expression profiles upon differentiation. Here we determine genome-wide transcription profiles during undirected differentiation of severely hypomethylated (Dnmt1⁻/⁻) embryonic stem cells (ESCs) as well as ESCs completely devoid of DNA methylation (Dnmt1⁻/⁻;Dnmt3a⁻/⁻;Dnmt3b⁻/⁻ or TKO) and assay their potential to transit in and out of the ESC state. We find that the expression of only few genes mainly associated with germ line function and the X chromosome is affected in undifferentiated TKO ESCs. Upon initial differentiation as embryoid bodies (EBs) wild type, Dnmt1⁻/⁻ and TKO cells downregulate pluripotency associated genes and upregulate lineage specific genes, but their transcription profiles progressively diverge upon prolonged EB culture. While Oct4 protein levels are completely and homogeneously suppressed, transcription of Oct4 and Nanog is not completely silenced even at late stages in both Dnmt1⁻/⁻ and TKO EBs. Despite late wild type and Dnmt1⁻/⁻ EBs showing a much higher degree of concordant expression, after EB dissociation and replating under pluripotency promoting conditions both Dnmt1⁻/⁻ and TKO cells, but not wild type cells rapidly revert to expression profiles typical of undifferentiated ESCs. Thus, while DNA methylation seems not to be critical for initial activation of differentiation programs, it is crucial for permanent restriction of developmental fate during differentiation

Restoration of 1325 teeth with partial-coverage crowns manufactured from high noble metal alloys: a retrospective case series 18.8 years after prosthetic delivery

Objectives: To evaluate long-term survival and success rates of conventionally cemented partial-coverage crowns (PCCs) manufactured from high noble metal alloys (hn). Material and methods: Restoration-, periodontal- and tooth-related criteria on patients, restored with a single or multiple conventionally cemented hnPCCs in a private dental office were collected from existing patient records. With regard to semi-annual follow-ups, data of the most recent clinical evaluations were considered. Kaplan-Meier and log-rank tests were used for statistical analyses. Level of significance was set at p <= .05. Results: Between 09/1983 and 09/2009, 1325 hnPCCs were conventionally cemented on 1325 teeth in 266 patients (mean age: 44.5 +/- 10.7 years). Due to various reasons, 81 hnPCCs showed complications, documenting a success rate of 93.9% after a mean observation period of 18.8 +/- 5.7 years. Of these, additional 14 restorations were counted as survival, resulting in a survival rate of 94.9%. Most frequent complications were periodontal issues (n = 29, 35.8%). Significantly higher success rates were documented for hnPCCs of patients aged between 37 and 51 years (p = .012). Conclusion: Partial-coverage crowns from high noble metal alloys showed excellent survival and success rates after a mean observation period of 18.8 +/- 5.7 years. Higher patient age was one of the risk factors. Clinical relevance: According to the results of this study, hnPCCs still represent an excellent therapeutic option-even in modern dentistry

Driving Big Data – Integration and Synchronization of Data Sources for Artificial Intelligence Applications with the Example of Truck Driver Work Stress and Strain Analysis

This paper contributes to the issue of big data analysis and data quality with the specific field of time synchronization. As a highly relevant use case, big data analysis of work stress and strain factors for driving professions is outlined. Drivers experience work stress and strain due to trends like traffic congestion, time pressure or worsening work conditions. Although a large professional group with 2.5 million (US) and 3.5 million (EU) truck drivers, scientific analysis of work stress and strain factors is scarce. Driver shortage is growing into a large-scale economic and societal challenge, especially for small businesses. Empirical investigations require big data approaches with sources like physiological and truck, traffic, weather, planning or accident data. For such challenges, accurate data is required, especially regarding time synchronization. Awareness among researchers and practitioners is key and first solution approaches are provided, connecting to many further Machine Learning and big data applications

Clinical Outcomes of Root-Analogue Implants Restored with Single Crowns or Fixed Dental Prostheses: A Retrospective Case Series

The objective was to investigate clinical and radiological outcomes of rehabilitations with root-analogue implants (RAIs). Patients restored with RAIs, supporting single crowns or fixed dental prostheses, were recruited for follow-up examinations. Besides clinical and esthetical evaluations, X-rays were taken and compared with the records. Patients were asked to evaluate the treatment using Visual Analogue Scales (VAS). For statistical analyses, mixed linear models were used. A total of 107 RAIs were installed in one dental office. Of these, 31 were available for follow-up examinations. For those remaining, survival has been verified via phone. RAIs were loaded after a mean healing time of 6.6 ± 2.5 months. 12.1 ± 6.9 months after loading, a mean marginal bone loss (MBL) of 1.20 ± 0.73 mm was measured. Progression of MBL significantly decreased after loading (p = 0.013). The mean pink and white esthetic score (PES/WES) was 15.35 ± 2.33 at follow-up. A survival rate of 94.4% was calculated after a mean follow-up of 18.9 ± 2.4 months after surgery. Immediate installation of RAIs does not seem to reduce MBL, as known from the literature regarding screw-type implants, and might not be recommended for daily routine. Nevertheless, they deliver esthetically satisfying results

Enhancement of the efficiency of non-viral gene delivery by application of pulsed magnetic field

New approaches to increase the efficiency of non-viral gene delivery are still required. Here we report a simple approach that enhances gene delivery using permanent and pulsating magnetic fields. DNA plasmids and novel DNA fragments (PCR products) containing sequence encoding for green fluorescent protein were coupled to polyethylenimine coated superparamagnetic nanoparticles (SPIONs). The complexes were added to cells that were subsequently exposed to permanent and pulsating magnetic fields. Presence of these magnetic fields significantly increased the transfection efficiency 40 times more than in cells not exposed to the magnetic field. The transfection efficiency was highest when the nanoparticles were sedimented on the permanent magnet before the application of the pulsating field, both for small (50 nm) and large (200-250 nm) nanoparticles. The highly efficient gene transfer already within 5 min shows that this technique is a powerful tool for future in vivo studies, where rapid gene delivery is required before systemic clearance or filtration of the gene vectors occur

Enhancement of the efficiency of non-viral gene delivery by application of pulsed magnetic field

New approaches to increase the efficiency of non-viral gene delivery are still required. Here we report a simple approach that enhances gene delivery using permanent and pulsating magnetic fields. DNA plasmids and novel DNA fragments (PCR products) containing sequence encoding for green fluorescent protein were coupled to polyethylenimine coated superparamagnetic nanoparticles (SPIONs). The complexes were added to cells that were subsequently exposed to permanent and pulsating magnetic fields. Presence of these magnetic fields significantly increased the transfection efficiency 40 times more than in cells not exposed to the magnetic field. The transfection efficiency was highest when the nanoparticles were sedimented on the permanent magnet before the application of the pulsating field, both for small (50 nm) and large (200–250 nm) nanoparticles. The highly efficient gene transfer already within 5 min shows that this technique is a powerful tool for future in vivo studies, where rapid gene delivery is required before systemic clearance or filtration of the gene vectors occurs

Current treatment options in RAS mutant metastatic colorectal cancer patients: a meta-analysis of 14 randomized phase III trials

PURPOSE Although biomarkers for patients with metastatic colorectal cancer exist, the benefit patients with RAS mutated tumors derive from established regimens is unclear. METHODS Efficacy of therapeutic strategies available for RAS mutated patients (addition of chemotherapeutic agents and/or anti angiogenic agents) were investigated in fourteen randomized controlled phase III trials at trial level by meta-analysing individual study hazard ratios and 95% confidence intervals (95% CI) for overall survival (OS) and progression free survival (PFS). RESULTS 6810 of 10,748 patients (63.3%) were available (48.5% RAS wildtype, 51.5% RAS mutated). Across all treatment lines, additional treatment efficacy (chemotherapy and/or anti angiogenic agents) was significantly smaller in RAS mutated compared to wildtype tumors for OS and PFS. In detail, patients with RAS mutated metastatic colorectal cancer derived significant benefit in PFS but not in OS by the addition of either chemotherapy or anti angiogenic agents to the respective comparator. In patients with RAS wildtype metastatic colorectal cancer, PFS and OS were improved by the addition of chemotherapy or anti angiogenic agent. CONCLUSION The therapeutic benefit of additional substances is less distinct in patients with RAS mutated as compared to RAS wildtype metastatic colorectal cancer, especially with regard to OS

Prevalence and Factors Associated with Fear of COVID-19 Among Homeless Individuals During the COVID-19 Pandemic: Evidence from the Hamburg Survey of Homeless Individuals.

PURPOSE: To clarify the prevalence and determinants of fear of COVID-19 among homeless individuals during the COVID-19 pandemic. PATIENTS AND METHODS: Data were taken from the Hamburg survey of homeless individuals (n=150) covering homeless adults in Hamburg, Germany. Multiple linear regressions were used. Beyond sociodemographic and lifestyle-related independent variables, COVID-19-related factors were also used as independent variables. RESULTS: In sum, 56.2% of homeless individuals reported no fear of COVID-19, 23.8% reported a little fear of COVID-19, 9.2% reported some fear of COVID-19 and 10.8% reported severe fear of COVID-19. Regressions showed that an increased fear of COVID-19 was significantly associated with younger age (β=-.01, p<0.05), absence of chronic alcohol consume (β=-.55, p<0.01), an increased perceived own risk of getting infected with the coronavirus one day (β=0.42, p<0.001) and a higher agreement that a diagnosis of the coronavirus would ruin his/her life (β=0.13, p<0.01). CONCLUSION: Given the poor hygienic conditions and their increased vulnerability, data surprisingly suggest a quite low fear of COVID-19 among homeless individuals. Efforts may be beneficial which contribute to thinking rationally about COVID-19 among homeless people, since low levels of fear of COVID-19 may contribute to careless behavior and can lead to super-spreading events