Entwicklung und Validierung eines Bioassays zum Nachweis induzierter Genaktivität für den Einsatz auf der Internationalen Raumstation

Neben der fehlenden Schwerkraft stellt die Strahlenbelastung des Astronauten einen limitierenden Faktor für den Langzeitaufenthalt des Menschen im Weltraum dar. Experimente zur Untersuchung einer möglichen Interaktion zwischen Mikrogravitation und der zellulären Strahlenantwort können auf der Erde nur unzureichend bearbeitet werden. Die Internationale Raumstation bietet als derzeit wichtigste Forschungsplattform eine Möglichkeit, dieser Fragestellung nachzugehen. Im Weltraumexperiment Cellpath soll eine geänderte Genexpression schadensrelevanter Gene unter Verwendung von indikativen Bioassays analysiert werden. Dazu sollte ein auf dem Rezeptor-Reporter-Prinzip basierendes, zelluläres Testsystem konzipiert werden. Um einen für diesen Zweck geeigneten Promotor- oder Enhancer zu finden, der die Rolle eines regulatorischen Elements übernimmt, wurde die Expression verschiedener Gene untersucht, deren Genprodukte in unterschiedlichen DNA-Reparaturwege involviert sind. Anhand einer in verschiedenen humanen Zelllinien (A549, MCF-7, AGS, HEK und NHF) durchgeführten strahlenbiologischen Charakterisierung wurden A549-Zellen als geeignete Wirtslinie für das Testsystem identifiziert. Die Ergebnisse der mittels quantitativer Real Time RT-PCR durchgeführten Genexpressionsstudien wiesen das p53R2 Gen als geeigneten Kandidaten für die Etablierung eines induzierbaren Bioassays aus. Für dessen Entwicklung wurde ein Vektorsystem konstruiert, das die Expression des Reportermoleküls EGFP unter der Kontrolle der p53-abhängigen Form der Ribonukleotid Reduktase (p53R2) als Sensor ermöglicht. Dazu wurde die Bindestelle für den Transkriptionsfaktor p53 aus dem 1. Intron des p53R2 Gens in den promotorlosen EGFP-Vektor kloniert und stabil in A549 Zellen transfiziert. Die Induzierbarkeit der rekombinanten Zelllinie A549-RRM2b wurde in biologischen Experimenten mit Strahlung unterschiedlicher Qualität überprüft. Die nach Exposition mit Röntgenstrahlen, beschleunigten Kohlenstoff- und Argon-Ionen erhaltenen Ergebnisse zeigen, dass der rekombinanten Zelllinie eine hohe Bedeutsamkeit für ein Weltraumexperiment zukommt

Controlling qubit networks in polynomial time

Future quantum devices often rely on favourable scaling with respect to the system components. To achieve desirable scaling, it is therefore crucial to implement unitary transformations in an efficient manner. We develop an upper bound for the minimum time required to implement a unitary transformation on a generic qubit network in which each of the qubits is subject to local time dependent controls. The set of gates is characterized that can be implemented in a time that scales at most polynomially in the number of qubits. Furthermore, we show how qubit systems can be concatenated through controllable two body interactions, making it possible to implement the gate set efficiently on the combined system. Finally a system is identified for which the gate set can be implemented with fewer controls. The considered model is particularly important, since it describes electron-nuclear spin interactions in NV centers

Emerging unitary evolutions in dissipatively coupled systems

Having a broad range of methods available for implementing unitary operations is crucial for quantum information tasks. We study a dissipative process commonly used to describe dissipatively coupled systems and show that the process can lead to pure unitary dynamics on one part of a bipartite system, provided that the process is strong enough. As a consequence of these findings, we discuss within the framework of quantum control theory how the dissipative process can enable universal control of the considered part, thereby turning parts of the system into a system capable of universal quantum information tasks. We characterize the time scales necessary to implement gates with high fidelity through the dissipative evolution. The considered dissipative evolution is of particular importance since it can be engineered in the laboratory in the realm of superconducting circuits. Based on a reservoir that is formed by a lossy microwave mode we present a detailed study of how our theoretical findings can be realized in an experimental setting

No temporal association between influenza outbreaks and invasive pneumococcal infections

Objective: To assess whether the influenza peak in populations precedes the annual peak for invasive pneumococcal infections (IPI) in winter.Design: Ecological study. Active surveillance data on influenza A and IPI in children up to 16 years of age collected from 1997 to 2003 were analysed.Setting: Paediatric hospitals in Germany.Patients: Children under 16 years of age.Results: In all years under study, the influenza A season did not appear to affect the IPI season (p = 0.49). Specifically, the influenza peak never preceded the IPI peak.Conclusion: On a population level there was no indication that the annual influenza epidemic triggered the winter increase in the IPI rate or the peak of the IPI distribution in children

Generation of two-mode entangled states by quantum reservoir engineering

A method for generating entangled cat states of two modes of a microwave cavity field is proposed. Entanglement results from the interaction of the field with a beam of atoms crossing the microwave resonator, giving rise to non-unitary dynamics of which the target entangled state is a fixed point. We analyse the robustness of the generated two-mode photonic "cat state" against dephasing and losses by means of numerical simulation. This proposal is an instance of quantum reservoir engineering of photonic systems.Comment: 8 pages, 7 figure

Delayed Gastric Emptying in Patients with Prader Willi Syndrome

Background: A 15 year old girl with Prader-Willi Syndrome (PWS) died of gastric rupture. Systematic literature research revealed seven case reports of PWS patients with acute gastric dilatation, two had a lethal course. The objective of this study was to determine if delayed gastric emptying in PWS patients might contribute to gastric dilatation. Methods: Gastric emptying was measured in eight patients with PWS by nucleotid scintigraphy after a standardized test meal. Results: Median age was 17.8 years (range 10.1-19.5). Median BMI of the male patients was 29.5 (range 18.4-34.8), of the female patients 28 (range 20.0-44.8). Half time of gastric emptying was delayed in five of the eight patients (median 78.5 minutes, range 59-134). Conclusion: Scintigraphic measurement of gastric emptying in eight PWS patients revealed delay in comparison to normal values. This might be a risk factor for gastric dilatation and rupture in patients with PW

Screening fungi isolated from historic Discovery Hut on Ross Island, Antarctica for cellulose degradation

To survive in Antarctica, early explorers of Antarctica's Heroic Age erected wooden buildings and brought in large quantities of supplies. The introduction of wood and other organic materials may have provided new nutrient sources for fungi that were indigenous to Antarctica or were brought in with the materials. From 30 samples taken from Discovery Hut, 156 filamentous fungi were isolated on selective media. Of these, 108 were screened for hydrolytic activity on carboxymethyl cellulose, of which 29 demonstrated activities. Endo-1, 4-β-glucanase activity was confirmed in the extracellular supernatant from seven isolates when grown at 4°C, and also when they were grown at 15°C. Cladosporium oxysporum and Geomyces sp. were shown to grow on a variety of synthetic cellulose substrates and to use cellulose as a nutrient source at temperate and cold temperatures. The research findings from the present study demonstrate that Antarctic filamentous fungi isolated from a variety of substrates (wood, straw, and food stuffs) are capable of cellulose degradation and can grow well at low temperatures