Molecular and functional characterization of biglycan during pathologic cardiac remodelling

Remodelling der extrazellulären Matrix (EZM) nach Myokardinfarkt (MI) ist auf der einen Seite verantwortlich für die Ausbildung eines stabilen Narbengewebes kann aber auf der anderen Seite zu pathologischen Veränderungen führen, welche die Herzfunktion nachträglich beeinträchtigen. Das kleine Leucin reiche Proteoglykan Biglykan (bgn) ist maßgeblich an diesem Prozess des Remodelling beteiligt. Nach MI differenzieren kardiale Fibroblasten zu Myofibroblasten. Myofibroblasten produzieren und reorganisieren die EZM und kontrahieren das Gewebe. Das Ziel der vorliegenden Arbeit war es zu untersuchen welche Rolle Biglykan für den Phänotypen kardialer Fibroblasten spielt. Kardiale Fibroblasten wurden aus Herzen von Wildtyp (WT) und biglykan-defizienten (bgn-/0) Mäusen isoliert. Bgn-/0-Fibroblasten zeigten einen deutlich pro-proliferativen Phänotyp. Dieser pro-proliferativen Phänotyp konnte sowohl durch eine WT-EZM als auch durch die lentivirale Transfektion mit einem Biglykanexpressionsvektor kompensiert werden. Die Charakterisierung der Biglykan defizienten Fibroblasten zeigte, das diese eine gesteigerte Expression von EZM vernetzenden Enzymen, Matrix Metalloproteinasen sowie des TGF-β Rezeptors II und CD44 haben. In Übereinstimmung mit diesen Ergebnissen konnte eine erhöhte Phosphorylierung von SMAD2 und ERK1/2 gezeigt werden. Des Weiteren konnte gezeigt werden, das die Behandlung der kardialen Fibroblasten mit einem neutralisierenden Antikörper gegen TGF-β zu einer Reversion des pro-proliferativen Phänotyps der bgn-/0-Fibroblasten führte. Bgn-/0-Fibroblasten zeigten die für eine Differenzierung zu Myofibroblasten charakteristische Inkorporation von alpha-smooth muscle Actin (α-SMA) in Stressfasern, eine erhöhte Expression fokaler Adhäsionen und einer gesteigerten Kollagen Gel Kontraktion. Interessanterweise zeigten bgn-/0-Fibroblasten eine erhöhte Apoptose unter normalen Zellkulturbedingungen. In vivo konnte gezeigt werden, das in WT-Mäusen die Expression von α-SMA an Tag drei nach MI am höchsten ist. Bemerkenswerterweise war bei den bgn-/0-Mäusen die Expression von α-SMA zusätzlich noch starker erhöht, was die Schlussfolgerung zulässt das die Biglykan Defizienz die Proliferation und Differenzierung von Myofibroblasten auch in vivo nach MI reguliert. Zum ersten Mal konnte gezeigt werden, dass die Differenzierung zu Myofibroblasten durch eine erhöhte Expression des Dystrophin assoziierten Protein Komplexes in vitro und in vivo begleitet wird. Die Hochregulation des Dystrophin Komplexes resultierte jedoch nicht in einer Induktion der nNOS Expression nach MI. Diese Daten unterstützen die Hypothese das bgn-/0-Fibroblasten spontan in Myofibroblasten differenzieren und alle charakteristischen Eigenschaften dieser aufweisen, aber hinsichtlich der Schlüsselfunktionen dieser Zellen gestört sind, was zu einer erhöhten Apoptose, verschlechterter Hämodynamik und fehlerhaften Narbenbildung führt. Schlussfolgernd deuten diese Ergebnisse eine inhibitorische Rolle von Biglykan während der Proliferation und Differenzierung kardialer Myofibroblasten an, die durch eine erhöhte Sensitivität gegenüber endogenem TGF-β und SMAD2 Signalling begründet ist.After myocardial infarction (MI) extracellular matrix (ECM) remodelling is on the one hand required for the formation of stable scar tissue but on the other hand can turn into pathologic remodelling. The small leucine-rich proteoglycan (SLRP) biglycan (bgn) has been shown to be critically involved in these processes. During post-ischemic remodelling cardiac fibroblasts differentiate into myofibroblasts which are the main cell type mediating ECM remodelling and scar contraction. Aim of the present study was to characterize the role of biglycan for the phenotype of cardiac fibroblasts. Cardiac fibroblasts were isolated from hearts of wild-type (WT) versus bgn-/0- mice. Phenotypical characterization of the bgn-/0-fibroblasts revealed increased proliferation that was suppressed to WT-level by WT-cell-derived ECM and by lentiviral restoration of biglycan expression. Characterization of bgn-/0-fibroblasts revealed increased expression levels of ECM crosslinking enzymes, as well as CD44 and TGF-βRII. In line with these results the phosphorylation of SMAD2 and ERK1/2 was increased and administration of neutralizing antibodies to TGF-β reversed the pro-proliferative phenotype. Furthermore, bgn-/0-fibroblasts were characterized by increased alpha-smooth muscle actin (α-SMA) incorporated into stress fibres, increased expression of focal adhesions and increased contraction of collagen gels, indicative for differentiation into myofibroblasts. Surprisingly, bgn-/0-fibroblasts showed increased apoptosis under normal conditions. In vivo in WT-hearts the time course of α-SMA expression post MI showed peak levels at 3 days. Of note in bgn-/0-mice the increase of α-SMA was markedly enhanced suggesting that biglycan deficiency also promotes myofibroblast proliferation and differentiation in vivo post MI. For the first time it was shown that myofibroblast differentiation caused by biglycan deficiency was accompanied by increased expression of the dystrophin associated protein complex in vitro and additionally in vivo. Importantly an up-regulation of the DAPC did not correlate with an induction of nNOS expression post infarction. This data support the hypothesis that bgn-/0-fibroblasts differentiate to myofibroblasts and exhibit characteristic features of this specialized cell type, but fail with respect to key functions, which results in apoptosis, impaired scar formation and disturbed hemodynamic function after MI. In conclusion these data point to an inhibitory role of biglycan during cardiac myofibroblasts proliferation and differentiation possibly due to increased sensitivity to endogenous TGF-β and SMAD2 signalling

The Far-Infrared--Radio Correlation at High Redshifts: Physical Considerations and Prospects for the Square Kilometer Array

(Abridged) I present a predictive analysis for the behavior of the FIR--radio correlation as a function of redshift in light of the deep radio continuum surveys which may become possible using the SKA. To keep a fixed ratio between the FIR and predominantly non-thermal radio continuum emission of a normal star-forming galaxy requires a nearly constant ratio between galaxy magnetic field and radiation field energy densities. While the additional term of IC losses off of the cosmic microwave background (CMB) is negligible in the local Universe, the rapid increase in the strength of the CMB energy density (i.e. $\sim(1+z)^{4})$ suggests that evolution in the FIR-radio correlation should occur with infrared (IR; 8-1000 \micron)/radio ratios increasing with redshift. At present, observations do not show such a trend with redshift; $z\sim6$ radio-quiet QSOs appear to lie on the local FIR-radio correlation while a sample of $z\sim4.4$ and $z\sim2.2$ SMGs exhibit ratios that are a factor of $\sim$2.5 {\it below} the canonical value. I also derive a 5$\sigma$ point-source sensitivity goal of $\approx$20 nJy (i.e. $\sigma_{\rm RMS} \sim 4$ nJy) requiring that the SKA specified be $A_{\rm eff}/T_{\rm sys}\approx 15000$ m$^{2}$ K$^{-1}$; achieving this sensitivity should enable the detection of galaxies forming stars at a rate of \ga25 M_{\sun} {\rm yr}^{-1}, at all redshifts if present. By taking advantage of the fact that the non-thermal component of a galaxy's radio continuum emission will be quickly suppressed by IC losses off of the CMB, leaving only the thermal (free-free) component, I argue that deep radio continuum surveys at frequencies \ga10 GHz may prove to be the best probe for characterizing the high-$z$ star formation history of the Universe unbiased by dust.Comment: 16 pages, 8 figures, accepted for publication in Ap

Difference Image Analysis of Galactic Microlensing I. Data Analysis

This is a preliminary report on the application of Difference Image Analysis (DIA) to galactic bulge images. The aim of this analysis is to increase the sensitivity to the detection of gravitational microlensing. We discuss how the DIA technique simplifies the process of discovering microlensing events by detecting only objects which have variable flux. We illustrate how the DIA technique is not limited to detection of so called ``pixel lensing'' events, but can also be used to improve photometry for classical microlensing events by removing the effects of blending. We will present a method whereby DIA can be used to reveal the true unblended colours, positions and light curves of microlensing events. We discuss the need for a technique to obtain the accurate microlensing time scales from blended sources, and present a possible solution to this problem using the existing HST colour magnitude diagrams of the galactic bulge and LMC. The use of such a solution with both classical and pixel microlensing searches is discussed. We show that one of the major causes of systematic noise in DIA is differential refraction. A technique for removing this systematic by effectively registering images to a common airmass is presented. Improvements to commonly used image differencing techniques are discussed.Comment: 18 pages, 8 figures, uses AAS LaTEX 4.0, To appear in Astrophysical Journa

New nurses burnout and workplace wellbeing:The influence of authentic leadership and psychological capital

The detrimental effects of burnout on nurses’ health and wellbeing are well documented and positive leadership has been shown to be an important organizational resource for discouraging the development of burnout. Intrapersonal resources also play a protective role against workplace stressors. This study investigated the influence of authentic leadership, an organizational resource, and psychological capital, an intrapersonal resource, on new graduate burnout, occupational satisfaction, and workplace mental health over the first year of employment (n = 205). Results supported the protective role of organizational and intrapersonal resources against burnout, job dissatisfaction, and mental health. © 2014 The Authors. Published by Elsevier GmbH. This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/)

Only marginal alignment of disc galaxies

Testing theories of angular-momentum acquisition of rotationally supported disc galaxies is the key to understand the formation of this type of galaxies. The tidal-torque theory tries to explain this acquisition process in a cosmological framework and predicts positive autocorrelations of angular-momentum orientation and spiral-arm handedness on distances of 1Mpc/h. This disc alignment can also cause systematic effects in weak-lensing measurements. Previous observations claimed discovering such correlations but did not account for errors in redshift, ellipticity and morphological classifications. We explain how to rigorously propagate all important errors. Analysing disc galaxies in the SDSS database, we find that positive autocorrelations of spiral-arm handedness and angular-momentum orientations on distances of 1Mpc/h are plausible but not statistically significant. This result agrees with a simple hypothesis test in the Local Group, where we find no evidence for disc alignment. Moreover, we demonstrate that ellipticity estimates based on second moments are strongly biased by galactic bulges, thereby corrupting correlation estimates and overestimating the impact of disc alignment on weak-lensing studies. Finally, we discuss the potential of future sky surveys. We argue that photometric redshifts have too large errors, i.e., PanSTARRS and LSST cannot be used. We also discuss potentials and problems of front-edge classifications of galaxy discs in order to improve estimates of angular-momentum orientation.Comment: 20 pages, 15 figures; accepted by MNRA

Prevalence of Human African Trypanosomiasis in the Democratic Republic of the Congo

Human African Trypanosomiasis (HAT) is a major public health problem in the Democratic Republic of the Congo (DRC). Active and passive surveillance for HAT is conducted but may underestimate the true prevalence of the disease. We used ELISA to screen 7,769 leftover dried blood spots from a nationally representative population-based survey, the 2007 Demographic and Health Survey. 26 samples were positive by ELISA. Three of these were also positive by trypanolysis and/or PCR. From these data, we estimate that there were 18,592 people with HAT (95% confidence interval, 4,883–32,302) in the DRC in 2007, slightly more than twice as many as were reported