435 research outputs found
Identifizierung der endothelspezifischen Rezeptor-Protein-Tyrosinphosphatase VE-PTP als VE-Cadherin-Ligand
Die Zell-Zell-Kontakte von Endothelzellen sind fĂźr die Aufrechterhaltung der Barriere zwischen dem BlutgefäĂsystem und dem umliegenden Gewebe verantwortlich. VE-Cadherin ist das essentielle Zell-AdhäsionsmolekĂźl der zonula adherentes in Endothelzellen. Veränderungen der Zell-Zell-Kontakte von Endothelzellen korrelieren häufig mit einer Tyrosinphosphorylierung von VE-Cadherin. In dieser Arbeit konnte gezeigt werden, dass die endothelspezifische Rezeptor-Protein-Tyrosinphosphatase VE-PTP (vascular endothelial-protein tyrosine phosphatase) mit VE-Cadherin co-präzipitiert wird. Diese Interaktion wird Ăźber die fĂźnfte Cadherindomäne von VE-Cadherin und der membranproximalen, extrazellulären 17. Fibronektin-III-Domäne von VE-PTP vermittelt. In COS-7 Zellen fĂźhrt die Co-transfektion von VE-Cadherin und VEGFR-2 (Flk-1) zu einer Tyrosinphosphorylierung von VE-Cadherin. Diese Phosphorylierung wird durch die zusätzliche Transfektion der katalytisch aktiven, jedoch nicht durch die Transfektion einer katalytisch inaktiven VE-PTP inhibiert
Improved estimation of Fokker-Planck equations through optimisation
An improved method for the description of hierarchical complex systems by
means of a Fokker-Planck equation is presented. In particular the
limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm for constraint
problems (L-BFGS-B) is used to minimize the distance between the numerical
solutions of the Fokker-Planck equation and the empirical probability density
functions and thus to estimate properly the drift and diffusion term of the
Fokker-Planck equation. The optimisation routine is applied to a time series of
velocity measurements obtained from a turbulent helium gas jet in order to
demonstrate the benefits and to quantify the improvements of this new
optimisation routine
An Iterative Procedure for the Estimation of Drift and Diffusion Coefficients of Langevin Processes
A general method is proposed which allows one to estimate drift and diffusion
coefficients of a stochastic process governed by a Langevin equation. It
extends a previously devised approach [R. Friedrich et al., Physics Letters A
271, 217 (2000)], which requires sufficiently high sampling rates. The analysis
is based on an iterative procedure minimizing the Kullback-Leibler distance
between measured and estimated two time joint probability distributions of the
process.Comment: 4 pages, 5 figure
From short to fat tails in financial markets: A unified description
In complex systems such as turbulent flows and financial markets, the
dynamics in long and short time-lags, signaled by Gaussian and fat-tailed
statistics, respectively, calls for a unified description. To address this
issue we analyze a real dataset, namely, price fluctuations, in a wide range of
temporal scales to embrace both regimes. By means of Kramers-Moyal (KM)
coefficients evaluated from empirical time series, we obtain the evolution
equation for the probability density function (PDF) of price returns. We also
present consistent asymptotic solutions for the timescale dependent equation
that emerges from the empirical analysis. From these solutions, new
relationships connecting PDF characteristics, such as tail exponents, to
parameters of KM coefficients arise. The results reveal a dynamical path that
leads from Gaussian to fat-tailed statistics, furnishing insights on other
complex systems where akin crossover is observed.Comment: 11 pages, 5 figure
Transplantation of porcine adrenal spheroids for the treatment of adrenal insufficiency
Primary adrenal insufficiency is a life-threatening disorder, which requires lifelong hormone replacement therapy. Transplantation of xenogeneic adrenal cells is a potential alternative approach for the treatment of adrenal insufficiency. For a successful outcome of this replacement therapy, transplanted cells should provide adequate hormone secretion and respond to adrenal physiological stimuli. Here, we describe the generation and characterization of primary porcine adrenal spheroids capable of replacing the function of adrenal glands in vivo. Cells within the spheroids morphologically resembled adult adrenocortical cells and synthesized and secreted adrenal steroid hormones in a regulated manner. Moreover, the embedding of the spheroids in alginate led to the formation of cellular elongations of steroidogenic cells migrating centripetally towards the inner part of the slab, similar to zona Fasciculata cells in the intact organ. Finally, transplantation of adrenal spheroids in adrenalectomized SCID mice reversed the adrenal insufficiency phenotype, which significantly improved animals' survival. Overall, such adrenal models could be employed for disease modeling and drug testing, and represent the first step toward potential clinical trials in the future
A multi-centre randomised controlled study of pre-IVF outpatient hysteroscopy in women with recurrent IVF implantation failure: Trial of Outpatient Hysteroscopy - [TROPHY] in IVF
<p>Abstract</p> <p>Background</p> <p>The success rate of IVF treatment is low. A recent systematic review and meta-analysis found that the outcome of IVF treatment could be improved in patients who have experienced recurrent implantation failure if an outpatient hysteroscopy (OH) is performed before starting the new treatment cycle. However, the trials were of variable quality, leading to a call for a large and high-quality randomised trial. This protocol describes a multi-centre randomised controlled trial to test the hypothesis that performing an OH prior to starting an IVF cycle improves the live birth rate of the subsequent IVF cycle in women who have experienced two to four failed IVF cycles.</p> <p>Methods and design</p> <p>Eligible and consenting women will be randomised to either OH or no OH using an internet based trial management programme that ensures allocation concealment and employs minimisation for important stratification variables including age, body mass index, basal follicle stimulating hormone level and number of previous failed IVF cycles. The primary outcome is live birth rate per IVF cycle started. Other outcomes include implantation, clinical pregnancy and miscarriage rates.</p> <p>The sample size for this study has been estimated as 758 participants with 379 participants in each arm. Interim analysis will be conducted by an independent Data Monitoring Committee (DMC), and final analysis will be by intention to treat. A favourable ethical opinion has been obtained (REC reference: 09/H0804/32).</p> <p>Trail Registration</p> <p>The trial has been assigned the following ISRCTN number: ISRCTN35859078</p
The role of cat eye narrowing movements in catâhuman communication
Domestic animals are sensitive to human cues that facilitate inter-specific communication, including cues to emotional state. The eyes are important in signalling emotions, with the act of narrowing the eyes appearing to be associated with positive emotional communication in a range of species. This study examines the communicatory significance of a widely reported cat behaviour that involves eye narrowing, referred to as the slow blink sequence. Slow blink sequences typically involve a series of half-blinks followed by either a prolonged eye narrow or an eye closure. Our first experiment revealed that cat half-blinks and eye narrowing occurred more frequently in response to ownersâ slow blink stimuli towards their cats (compared to no ownerâcat interaction). In a second experiment, this time where an experimenter provided the slow blink stimulus, cats had a higher propensity to approach the experimenter after a slow blink interaction than when they had adopted a neutral expression. Collectively, our results suggest that slow blink sequences may function as a form of positive emotional communication between cats and humans
Carbon-Nanotube-Embedded Hydrogel Sheets for Engineering Cardiac Constructs and Bioactuators
We engineered functional cardiac patches by seeding neonatal rat cardiomyocytes onto carbon nanotube (CNT)-incorporated photo-cross-linkable gelatin methacrylate (GelMA) hydrogels. The resulting cardiac constructs showed excellent mechanical integrity and advanced electrophysiological functions. Specifically, myocardial tissues cultured on 50 Îźm thick CNT-GelMA showed 3 times higher spontaneous synchronous beating rates and 85% lower excitation threshold, compared to those cultured on pristine GelMA hydrogels. Our results indicate that the electrically conductive and nanofibrous networks formed by CNTs within a porous gelatin framework are the key characteristics of CNT-GelMA leading to improved cardiac cell adhesion, organization, and cellâcell coupling. Centimeter-scale patches were released from glass substrates to form 3D biohybrid actuators, which showed controllable linear cyclic contraction/extension, pumping, and swimming actuations. In addition, we demonstrate for the first time that cardiac tissues cultured on CNT-GelMA resist damage by a model cardiac inhibitor as well as a cytotoxic compound. Therefore, incorporation of CNTs into gelatin, and potentially other biomaterials, could be useful in creating multifunctional cardiac scaffolds for both therapeutic purposes and in vitro studies. These hybrid materials could also be used for neuron and other muscle cells to create tissue constructs with improved organization, electroactivity, and mechanical integrity.United States. Army Research Office. Institute for Soldier NanotechnologiesNational Institutes of Health (U.S.) (HL092836)National Institutes of Health (U.S.) (EB02597)National Institutes of Health (U.S.) (AR057837)National Institutes of Health (U.S.) (HL099073)National Science Foundation (U.S.) (DMR0847287)United States. Office of Naval Research (ONR PECASE Award)United States. Office of Naval Research (Young Investigator award)National Research Foundation of Korea (grant (NRF-2010-220-D00014)
- âŚ