Expression von Parathormone-related Peptide in koronaren Endothelzellen und der glatten Gefäßmuskulatur

Das Parathormon related peptide (PTHrP) wird im gesamten Gefäßsystem einschließlich der koronaren Endothelzellen exprimiert. Im Gegensatz zu den benachbarten Glattmuskelzellen, welche bislang hinsichtlich PTHrP eingehend untersucht wurden, hat man die koronaren Endothelzellen nur als Produktionsstätte des Ventrikels angesehen. Aus diesem Grund blieben bisher die PTHrP-Expression und seine biologische Rolle in diesen Zellen ungeklärt. Deshalb habe ich mich dafür interessiert, ob eine Stimulation a-adrenerger bzw. AT-Rezeptoren die Expression in den koronaren Endothelzellen steigert und ob das endogen exprimierte PTHrP einen sogenannten intrakrinen Effekt in diesem Zelltyp ausübt. Besonders interessant ist diese Fragestellung vor dem Hintergrund, daß diese Zellen keine klassischen Zielzellen des Peptidhormones darstellen, da sie nicht den korrespondierenden PTHrP-Rezeptor besitzen, wie das z. B. bei den Glattmuskelzellen der Fall ist. Was anhand der Ergebnisse gezeigt werden konnte ist die Tatsache, daß durch Stimulation der Zellen mit der a-adrenergen Substanz Phenylephrin im Vergleich zur Stimulation mit Angiotensin II, eine deutliche Steigerung in der Expression des PTHrP hervorgerufen werden konnte. Dieser Effekt konnte jedoch nicht im Stadium der Konfluenz reproduziert werden. Im Gegensatz dazu erhielten wir in den Glattmuskelzellen ein genau umgekehrtes Bild, da hier nur Angiotensin II eine signifikante Expressionssteigerung hervorrief. Deshalb wollte ich mehr über die Lokalisation des endogenen PTHrP in den verschiedenen Proliferationsstadien mit Hilfe der Immunfluoreszenz in Erfahrung bringen. Die Ergebnisse zeigten, daß der Anteil an PTHrP, welcher in den Kern transloziert wird, umso größer ist, je mehr sich die Zellen dem Konfluenzstadium nähern. Diese Tatsache war für mich Anlaß zu vermuten, daß das Peptidhormon einen intrakrinen Effekt auf die koronaren Endothelzellen ausübt. Mit Hilfe der Transfektion der Zellen mit Antisense-Oligonukleotiden gegen PTHrP und der daraus sich ergebenden Herabregulierung seiner Expression untersuchte ich seinen möglichen Einfluß auf die Proliferation bzw. Apoptose. Im Bezug auf die Proliferation ergaben sich keine Hinweise auf eine Beeinflussung. Bei der Betrachtung der Endothelzellen in den unterschiedlichen Konfluenzstadien konnte mit Hilfe einer UV-Bestrahlung in Zellen, in denen der Anteil des nukleären PTHrP normalerweise erhöht wäre, eine stärkere Apoptoserate als unter Basalbedingungen hervorgerufen werden. Im Gegensatz dazu wurde durch eine erhöhte Expression des PTHrP - welche durch Phenylephrin vermittelte wurde -der Anteil der apoptotischen Zellen sowohl gegenüber Basalbedingungen als auch unter UV-Induktion deutlich vermindert. Zusammenfassend läßt sich anhand der Ergebnisse der vorliegenden Studie sagen, daß in koronaren Endothelzellen die PTHrP-Expression durch eine a-Adrenozeptor-Stimulation in einer Zellzyklus-abhängigen und Zelltyp-spezifischen Art und Weise reguliert wird. Diese Studie zeigt eine neue biologische Rolle des PTHrP im Gefäßbett auf, da über den nachgewiesenen intrakrinen Effekt das Peptidhormon einen Anteil am Schutzmechanismus der Endothelschicht vor Apoptose besitzt.Parathyroid hormone related peptide (PTHrP) is expressed throughout the vascular system including coronary endothelial cells. The regulation of endothelial PTHrP expression and the role of PTHrP expression in endothelial cells is not clear. The present study investigates the question whether stimulation of a-adrenergic or angiotensin II receptors increases endothelial expression of PTHrP and whether endogenously expressed PTHrP exerts intracrine effects in coronary endothelial cells. It was found that stimulation of alpha1A-adrenoceptors, but not that of angiotensin II, increases cellular expression of PTHrP in growing, but not in growth arrested, coronary endothelial cells. Angiotensin II increases the expression of PTHrP in smooth muscle cells, but not in endothelial cells. PTHrP enters the nucleus of endothelial cells at the stadium of confluence. This suggests an intracrine effect of PTHrP. It was further investigated whether downregulation of endogenous PTHrP expression by transfection with antisense oligonucleotides alters cell proliferation or apoptosis resistance in growing or non-growing endothelial cells. Downregulation of PTHrP did not modify cell proliferation but increased the amount of UV-induced apoptosis. An increased expression of PTHrP in cells pre-treated with an a-adrenoceptor agonist reduced basal rate of apoptosis and improved resistance against UV-induced apoptosis. These results indicate a novel intracrine effect of PTHrP in coronary endothelial cells that improves cell survival. In endothelial cells, the expression of PTHrP is regulated by alpha-adrenoceptor stimulation in a cell-cycle dependent and cell-type specific manner

Unified dark energy models : a phenomenological approach

A phenomenological approach is proposed to the problem of universe accelerated expansion and of the dark energy nature. A general class of models is introduced whose energy density depends on the redshift $z$ in such a way that a smooth transition among the three main phases of the universe evolution (radiation era, matter domination, asymptotical de Sitter state) is naturally achieved. We use the estimated age of the universe, the Hubble diagram of Type Ia Supernovae and the angular size - redshift relation for compact and ultracompact radio structures to test whether the model is in agreement with astrophysical observation and to constrain its main parameters. Although phenomenologically motivated, the model may be straightforwardly interpreted as a two fluids scenario in which the quintessence is generated by a suitably chosen scalar field potential. On the other hand, the same model may also be read in the context of unified dark energy models or in the framework of modified Friedmann equation theories.Comment: 12 pages, 10 figures, accepted for publication on Physical Review

Identification of alpha-enolase as an autoantigen in lung cancer: Its overexpression is associated with clinical outcomes

Purpose: Although existence of humoral immunity has been previously shown in malignant pleural effusions, only a limited number of immunogenic tumor-associated antigens (TAA) have been identified and associated with lung cancer. In this study, we intended to identify more TAAs in pleural effusion-derived tumor cells. Experimental Design: Using morphologically normal lung tissues as a control lysate in Western blotting analyses, 54 tumor samples were screened with autologous effusion antibodies. Biochemical purification and mass spectrometric identification of TAAs were done using established effusion tumor cell lines as antigen sources. We identified a p48 antigen as of-enolase (ENO1). Semiquantitative immunohistochemistry was used to evaluate expression status of ENO1 in the tissue samples of 80 patients with non-small cell lung cancer (NSCLC) and then correlated with clinical variables. Results: Using ENO1-specifc antiserum, up-regulation of ENO1 expression in effusion tumor cells from 11 of 17 patients was clearly observed compared with human normal lung primary epithelial and non-cancer-associated effusion cells. Immunohistochemical studies consistently showed high level of ENO1 expression in all the tumors we have examined thus far. Log-rank and Cox's analyses of ENO1 expression status revealed that its expression level in primary tumors was a key factor contributing to overall- and progression-free survivals of patients (P < 0.05). The same result was also obtained in the early stage of NSCLC patients, showing that tumors expressing relatively higher ENO1 level were tightly correlated with poorer survival outcomes. Conclusions: Our data strongly support a prognostic role of ENO1 in determining tumor malignancy of patients with NSCLC

Search for exotic neutrino-electron interactions using solar neutrinos in XMASS-I

We have searched for exotic neutrino-electron interactions that could be produced by a neutrino millicharge, by a neutrino magnetic moment, or by dark photons using solar neutrinos in the XMASS-I liquid xenon detector. We observed no significant signals in 711 days of data. We obtain an upper limit for neutrino millicharge of 5.4 × 10−12e at 90% confidence level assuming all three species of neutrino have common millicharge. We also set flavor-dependent limits assuming the respective neutrino flavor is the only one carrying a millicharge, 7.3 × 10−12e for νe , 1.1 × 10−11e for νμ, and 1.1 × 10−11e for ντ . These limits are the most stringent yet obtained from direct measurements. We also obtain an upper limit for the neutrino magnetic moment of 1.8 × 10−10 Bohr magnetons. In addition, we obtain upper limits for the coupling constant of dark photons in the U(1)B−L model of 1.3 × 10−6 if the dark photon mass is 1 × 10−3 MeV/c2, and 8.8 × 10−5 if it is 10 MeV/c2

Physical Processes in Star Formation

© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00693-8.Star formation is a complex multi-scale phenomenon that is of significant importance for astrophysics in general. Stars and star formation are key pillars in observational astronomy from local star forming regions in the Milky Way up to high-redshift galaxies. From a theoretical perspective, star formation and feedback processes (radiation, winds, and supernovae) play a pivotal role in advancing our understanding of the physical processes at work, both individually and of their interactions. In this review we will give an overview of the main processes that are important for the understanding of star formation. We start with an observationally motivated view on star formation from a global perspective and outline the general paradigm of the life-cycle of molecular clouds, in which star formation is the key process to close the cycle. After that we focus on the thermal and chemical aspects in star forming regions, discuss turbulence and magnetic fields as well as gravitational forces. Finally, we review the most important stellar feedback mechanisms.Peer reviewedFinal Accepted Versio

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society