Mortalität und Morbidität von chronischen Dialysepatienten bei Besiedlung mit Methicillin-sensiblem Staphylococcus aureus sowie Methicillin-resistentem Staphylococcus aureus

Systemische Infektionen mit S. aureus (MSSA und MRSA) und Infektionen des Gefäßzugangs bei HD-Patienten sind eine der wichtigsten Ursachen für Morbidität und Mortalität in dieser speziellen Population. Infektionsrisikos stellen die zunehmende Verwendung von Fremdkörpern, wie Katheter und Graft als Gefäßzugänge, sowie die intensivmedizinische Behandlung bei älteren und multimorbiden Patienten dar. Unter den bakteriell bedingten Infektionen bleiben Staphylokokken der am häufigsten nachgewiesene Stamm. Mit dem zunehmenden Gebrauch von Vancomycin zur Behandlung von MSSA-Infektionen hat das Vorkommen von MRSA zugenommen. Dies macht die Entwicklung von alternativen Antibiotikaregimen nötig, die eine Selektion von MRSA-Spezies verhindern. Unter dieser Überlegung wurde auf die Behandlung mit Vancomycin bei Zugangs-bezogenen Infektionen verzichtet. Es wurde im Jahr 2000 durch ein Standardregime bestehend aus Flucloxacillin und Rifampicin ersetzt. Mithilfe eines Screeningprogramms wurde nach MSSA- (n=88) und MRSA- (n=1) Kolonisationen gesucht. Dies gelang mit Hilfe von Querschnitts-Screenings und Indikations-Screeninguntersuchungen bei Aufnahme über den Zeitraum von 2000 bis 2010. Eine Besiedlung mit MRSA wurde bei nur einem Patienten während des 10-Jahres-Screenings registriert. Die gefundenen MSSA-Kolonisationen bei HD-Patienten beeinflussten die Morbidität und Mortalität nicht. Die Anzahl an HD-Patienten mit MSSA-Kolonisation nahm während des Beobachtungszeitraums von zehn Jahren ab Behandlungen mit dem Vancomycin-freien Regime waren generell erfolgreich und resultierten in einem Rückgang der klinischen und laborativen Infektionsmarker und/oder negativen Blutkulturen. Es konnte gezeigt werden, dass mit dem Gebrauch von vancomycinfreien Antibiotikaregimen ein erfolgreiches Management von Staphylokokkus-assoziierten Zugangsinfektionen bei HD-Patienten möglich ist

Positive effect of the combination of multilevel contracture release and glucocorticoid treatment in Duchenne muscular dystrophy

Purpose: In the 1980s the first results of an early multilevel contracture release (MLCR) in patients suffering from progressive Duchenne muscular dystrophy (DMD) showed a positive effect on ambulation. Despite the demonstrated positive effects of prolongation of walking this treatment is not part of current guidelines. The aim of our study was to evaluate the effect of MLCR as well as its combination with glucocorticoid (GC) treatment on ambulation. Methods: Data of all boys (n = 86) with DMD treated in our outpatient department were analyzed regarding the treatment and loss of independent ambulation. In all, 23 were treated with GC only, ten were operated on, 21 received GC and underwent MLCR and 32 received neither of the two treatments. Results: The analysis of the loss of independent ambulation in our cohort showed a comparable extension of the ambulatory period between the GC-treated and MLCR-treated boys (p = 0.008 and p = 0.005, respectively). Furthermore, an additive effect of both therapies was found; patients with DMD who had both treatments were able to walk two years longer than those with only one of the two treatment options (p<0.001). Conclusion: Standard GC treatment and early MLCR in lower limbs have an independent positive effect on prolongation of ambulation in patients with DMD. In our cohort, the combination of both therapies is significantly more effective than each therapy alone. We suggest both should be offered to all DMD patients eligible. Level of evidence: III

Application of the Predictor-Based Subspace Identification Method to Rotorcraft System Identification

In this paper, the optimized predictor-based subspace identification (PBSIDopt) method is applied to identify linear models of DLR's research helicopter ACT/FHS and to evaluate its usage to enhance existing physics based models in the future. For this effort, dedicated identification flight test data is used. This paper first describes the well known Maximum Likelihood frequency domain output error method and the applied physical model briefly. Then, the PBSIDopt method is presented and parameters, which influence the identification process, are discussed. Results from both methods using the same flight test data of the ACT/FHS are compared; model accuracy, order and missing dynamics are investigated. Advantages and disadvantages of both methods are evaluated and the applicability of the PBSIDopt method to rotorcraft system identification and its usage to improve the existing physical model structure is discussed

Investigating Power Benefits for a Helicopter by Variation of the Anti-Torque Device

With the usage of electrically driven devices, the rigid connection between main rotor and tail rotor can be broken up, allowing for a tail section that can possibly be optimized for different operating conditions. This paper presents the results of a study investigating the power benefits of different variations of the electric anti-torque device. The investigations were performed using an engineering model of a main rotor - tail rotor helicopter built up in the Versatile Aeromechanics Simulation Tool (VAST). The studied variations include horizontal and vertical tilting of the tail rotor, changing tail rotor speed and fin angle as well as fin size and geometry. Various flight conditions such as hover, forward flight, quartering flight, climb, and descent have been investigated. The largest power benefits were observed for (1) a combination of reduced tail rotor speed and a fin angle varying between 12 deg for low speed forward flight and 6 deg for high flight speeds and (2) an increased fin area with the tail rotor being shut off for flight speeds above 35 m/s

Human duodenal organoid-derived monolayers serve as a suitable barrier model for duodenal tissue

Usually, duodenal barriers are investigated using intestinal cell lines like Caco-2, which in contrast to native tissue are limited in cell-type representation. Organoids can consist of all intestinal cell types and are supposed to better reflect the in vivo situation. Growing three-dimensionally, with the apical side facing the lumen, application of typical physiological techniques to analyze the barrier is difficult. Organoid-derived monolayers (ODMs) were developed to overcome this. After optimizing culturing conditions, ODMs were characterized and compared to Caco-2 and duodenal tissue. Tight junction composition and appearance were analyzed, and electrophysiological barrier properties, like paracellular and transcellular barrier function and macromolecule permeability, were evaluated. Furthermore, transcriptomic data were analyzed. ODMs had tight junction protein expression and paracellular barrier properties much more resembling the originating tissue than Caco-2. Transcellular barrier was similar between ODMs and native tissue but was increased in Caco-2. Transcriptomic data showed that Caco-2 expressed fewer solute carriers than ODMs and native tissue. In conclusion, while Caco-2 cells differ mostly in transcellular properties, ODMs reflect trans- and paracellular properties of the originating tissue. If cultured under optimized conditions, ODMs possess reproducible functionality, and the variety of different cell types makes them a suitable model for human tissue-specific investigations.Peer Reviewe

Retrospective and Recent Examples of Aircraft and Rotorcraft System Identification at DLR

Aircraft system identification has a five-decades-long tradition at German Aerospace Center (DLR). Over the last two decades, the research covered various topics related to system identification of fixed- and rotary-wing aircraft, nonconventional applications and atmospheric effects, the development of new flight-test procedures for system identification purposes, and specific aircraft model enhancements and corresponding parameter estimation. Comprehensive tools were developed that support this research and can be applied to a variety of different problems and types of vehicles. The paper starts with a short description of the different system identification methods used at DLR and the corresponding tools. The discussion of flight-test procedures and maneuver design as well as sensor fusion and flight-path reconstruction provides information on how to optimize the flight tests for system identification and to arrive at a consistent flight-test database. The examples for fixed-wing aircraft provide information on identification including abnormal conditions such as icing and interaction with atmospheric disturbances as well as modeling of structural mechanics and loads. The identification of high-order rotorcraft models that account for rotor and engine dynamics and even structural modes is discussed, and the identification of rotor mast moments as well as the identification of non-physics-based models and their integration into physics-based models are also covered. A final section shows that system identification can also be used to derive models for gyroplanes and parachutes as well as to derive control equivalent turbulence input models and to estimate complex wind field geometries. Thus, a broad overview of possible applications of system identification is given

Expression of tricellular tight junction proteins and the paracellular macromolecule barrier are recovered in remission of ulcerative colitis

Background: Ulcerative colitis (UC) has a relapsing and remitting pattern, wherein the underlying mechanisms of the relapse might involve an enhanced uptake of luminal antigens which stimulate the immune response. The tricellular tight junction protein, tricellulin, takes charge of preventing paracellular passage of macromolecules. It is characterized by downregulated expression in active UC and its correct localization is regulated by angulins. We thus analyzed the tricellulin and angulin expression as well as intestinal barrier function and aimed to determine the role of tricellulin in the mechanisms of relapse. Methods: Colon biopsies were collected from controls and UC patients who underwent colonoscopy at the central endoscopy department of Campus Benjamin Franklin, Charite - Universitatsmedizin Berlin. Remission of UC was defined basing on the clinical appearance and a normal Mayo endoscopic subscore. Intestinal barrier function was evaluated by electrophysiological and paracellular flux measurements on biopsies mounted in Ussing chambers. Results: The downregulated tricellulin expression in active UC was recovered in remission UC to control values. Likewise, angulins were in remission UC at the same levels as in controls. Also, the epithelial resistance which was decreased in active UC was restored in remission to the same range as in controls, along with the unaltered paracellular permeabilities for fluorescein and FITC-dextran 4 kDa. Conclusions: In remission of UC, tricellulin expression level as well as intestinal barrier functions were restored to normal, after they were impaired in active UC. This points toward a re-sealing of the impaired tricellular paracellular pathway and abated uptake of antigens to normal rates in remission of UC

Einmal begeistert, immer begeistert? Eine Experience-Sampling-Studie zur wahrgenommenen Unterrichtsqualität und Motivation von Schülerinnen und Schülern im Kunstunterricht

Zahlreiche Studien in der quantitativ-empirischen Unterrichtsforschung folgen zwar theoretisch der Angebots-Nutzungskonzeption unterrichtlicher Wirkungen, basieren jedoch auf retrospektiv erhobenen Unterrichtswahrnehmungen oder Beobachtungsdaten und können daher wenig Aussagen über das subjektive Erleben von Lernenden während des Unterrichts machen. Befunde zur intraindividuellen Varianz von wahrgenommener Unterrichtsqualität und Motivation im Unterricht sowie zu intraindividuellen Zusammenhängen würden helfen, unterrichtliche Wirkungen unter Angebots-Nutzungsperspektive noch besser zu verstehen. Dieses Desiderat aufgreifend wurden in vorliegender Studie Lernende mittels Experience-Sampling Methode zu mehreren Zeitpunkten im Verlauf zweier Doppelstunden Kunstunterricht zu ihrer Unterrichtsqualitätswahrnehmung und Motivation befragt. Darüber hinaus wurde die Erfüllung der Bedürfnisse nach Kompetenz und Autonomie als Indikatoren für die individuelle Nutzung des Angebots als potenzielle Mediatorvariablen erfragt. Auf Basis einer Stichprobe von 222 Lernenden aus 9 Klassen der 9. Jahrgangsstufe des Gymnasiums und der Integrierten Gesamtschule zeigten sich folgende Ergebnisse: 1) Der größte Teil der Varianz in den Einschätzungen aller Konstrukte der Lernenden lag zwischen den Zeitpunkten, gefolgt von der Varianz zwischen den Personen; zwischen den Klassen variierten die Einschätzungen kaum. 2) Es konnten charakteristische Verlaufsformen einiger erhobener Einschätzungen über die beiden Doppelstunden ermittelt werden. 3) Vor allem auf intraindividueller Ebene wurden neben direkten Effekten der Unterrichtswahrnehmungen auf die selbstbestimmte Motivation auch indirekte über die wahrgenommene Autonomieunterstützung sichtbar. Die Ergebnisse helfen zu verstehen, wie wahrgenommene Unterrichtsqualität, individuelle Nutzung (Erfüllung des Bedürfnisses nach Autonomie) und selbstbestimmte Motivation im Unterrichtsverlauf zusammenspielen und es wird diskutiert, welche weiterführenden Studien folgen sollten. (DIPF/Orig.)Numerous studies in quantitative-empirical classroom research theoretically follow the supply-use conception of instructional effects, but they are based on retrospectively assessed classroom perceptions or observational data and can therefore make few statements about the subjective experience of learners during instruction. Findings on intraindividual variances of classroom perceptions and motivation as well as on intraindividual relationships would help to better understand instructional effects from a supply-use perspective. In the present study, teaching perceptions and motivation were surveyed at several points in time in the course of two double lessons of art instruction using the experience-sampling method. Additionally, satisfaction of the needs for competence and autonomy were assessed as indicators for the individual use of the supplied instruction and potential mediator variable. Based on a sample of 222 learners from 9 classes of the 9th grade of the \u27Gymnasium\u27 and the \u27Integrierte Gesamtschule\u27, the following results emerged: 1) Most of the variance in the learners\u27 estimations was found between time points (within-level), followed by the variance between individuals (between-level); between classes, the assessments hardly varied (class level). 2) Characteristic courses of some elicited constructs across the two double lessons could be identified. 3) Particularly at the intraindividual level, indirect effects via perceived autonomy support became apparent in addition to direct effects of instructional perceptions on self-determined motivation. The results help to understand how perceptions of instructional quality, satisfaction of the need for autonomy (as indicator for the individual use of the supplied instruction) and self-determined motivation look like in the course of a double lesson and it is discussed which further studies should follow. (DIPF/Orig.

The mentor-mentee relationship between student teachers and their mentors

Bestehende Forschungen zu Schulpraktika konzentrieren sich vor allem auf die Gruppe der Studierenden. Befunde zu den Betreuungspersonen und zur Interaktion beider Gruppen fehlen bisher und stellen ein Desiderat dar. Dem folgend diskutieren in der vorliegenden Studie Studierende im Praktikum und ihre betreuenden Lehrkräfte Bedingungen einer gelingenden Beziehung und Zusammenarbeit. Diese geben auch Aufschluss darüber, welche Konzeptionen von Beziehung und welche Rollengefüge beide Seiten als förderlich für ihre Interaktion wahrnehmen. Die Stichprobe umfasst 57 Studierende und 99 Praktikumslehrkräfte aus Grund- und Mittelschulen, rekrutiert im Rahmen eines Praktikums, das sich über ein Schuljahr verteilt. Die Auswertung der 21 Gruppendiskussionen erfolgte inhaltsanalytisch. Ein zentrales alle Kategorien übergreifend charakterisierendes Ergebnis ist, dass die Gelingensbedingungen aus Sicht von Studierenden und Lehrkräften eine Auflösung tradierter Meister-Lehrlings-Modelle widerspiegeln. Sie sind an einer symmetrischen Beziehungsgestaltung orientiert und beruhen auf reziprokem Agieren und einer gemeinsamen Verantwortung aller Akteur:innen. Hierarchische Abstufungen zeigen sich dort überholt, wo Studierende ihren Mentor:innen kritisches Feedback geben dürfen und sollen bzw. wo Mentor:innen ihren eigenen Unterricht zur Diskussion stellen und bereit sind, von Studierenden zu lernen. Die kollegiale Zusammenarbeit auf Augenhöhe ist allerdings an Erwartungen der Mentor:innen hinsichtlich des Verhaltens der Studierenden gebunden. Abschließend werden Desiderate der praktischen Implementierung und der wissenschaftlichen Evaluierung diskutiert. (DIPF/Orig.)Existing research on school practicum focuses mainly on the group of student teachers. Findings on the mentor teachers and even more on the interaction of both groups are missing. In the present study, student teachers and mentor teachers discuss the conditions for a successful relationship and collaboration. These conditions provide information about the conceptions of relationship and the role structures both sides perceive as beneficial for their interaction. The sample consists of 57 student teachers and 99 mentor teachers from primary and lower secondary schools. The participants were part of a one-school-year teacher practicum. The 21 group discussions were analyzed using content analysis. A central result across all categories is that conditions of success reflect the dissolution of traditional master-apprenticeship models from both the perspective of student teachers and mentor teachers. Instead, they are orientated towards a symmetrical relationship as well as reciprocal action and shared responsibility. Hierarchies appear to be outdated where teacher students are allowed and expected to give critical feedback to their mentor teachers, where mentor teachers are willing to discuss with and learn from student teachers. However, collegial collaboration on an equal basis is linked to mentors’ expectations of mentees’ behavior. Finally, desiderata for the practical implementation and scientific evaluation are discussed. (DIPF/Orig.

Beechwood carbohydrates for enzymatic synthesis of sustainable glycolipids

Moving away from crude oil to renewable resources for the production of a wide range of compounds is a challenge for future generations. To overcome this, the use of lignocellulose as substrate can contribute to drastically reduce the consumption of crude oil. In this study, sugars from lignocellulose were used as a starting material for the enzymatic synthesis of surface-active sugar esters. The substrates were obtained by an acid-catalyzed, beechwood pretreatment process, which resulted in a fiber fraction that is subsequently hydrolyzed to obtain the monosaccharides. After purification and drying, this glucose- and xylose-rich fraction was used to create a deep eutectic solvent, which acts both as solvent and substrate for the lipase-catalyzed reaction at the same time. Finally, the successful synthesis of glycolipids from a sustainable resource was confirmed by ESI–Q–ToF mass spectrometry and multidimensional NMR experiments. Moreover, conversion yields of 4.8% were determined by LC–MS/MS