Primitiver neuroektodermaler Tumor im Hoden: Molekulare Analyse und Diskussion der Entstehung

Zusammenfassung: Wir beschreiben einen testikulären primitiven neuroektodermalen Tumor (PNET) mit intratubulärer Keimzellneoplasie des angrenzenden Hodenparenchyms bei einem 25-jährigen Patienten. Testikuläre PNET sind selten. Ihre Entstehung wird auf eine maligne somatische Transformation in einem testikulären Keimzelltumor zurückgeführt. Morphologisch und molekularpathologisch ähneln diese Tumoren kindlichen zentralen PNET, die keine Rearrangierung des EWS-Gens auf Chromosom22 aufweisen. Auch im hier beschriebenen Fall konnte keine Translokation nachgewiesen werde

Spin dynamics of low-dimensional excitons due to acoustic phonons

We investigate the spin dynamics of excitons interacting with acoustic phonons in quantum wells, quantum wires and quantum disks by employing a multiband model based on the $4\times4$ Luttinger Hamiltonian. We also use the Bir-Pikus Hamiltonian to model the coupling of excitons to both longitudinal acoustic phonons and transverse acoustic phonons, thereby providing us with a realistic framework in which to determine details of the spin dynamics of excitons. We use a fractional dimensional formulation to model the excitonic wavefunctions and we demonstrate explicitly the decrease of spin relaxation time with dimensionality. Our numerical results are consistent with experimental results of spin relaxation times for various configurations of the GaAs/Al$_{0.3}$Ga$_{0.7}$As material system. We find that longitudinal and transverse acoustic phonons are equally significant in processes of exciton spin relaxations involving acoustic phonons.Comment: 24 pages, 3 figure

Bosonization and generalized Mandelstam soliton operators

The generalized massive Thirring model (GMT) with three fermion species is bosonized in the context of the functional integral and operator formulations and shown to be equivalent to a generalized sine-Gordon model (GSG) with three interacting soliton species. The generalized Mandelstam soliton operators are constructed and the fermion-boson mapping is established through a set of generalized bosonization rules in a quotient positive definite Hilbert space of states. Each fermion species is mapped to its corresponding soliton in the spirit of particle/soliton duality of Abelian bosonization. In the semi-classical limit one recovers the so-called SU(3) affine Toda model coupled to matter fields (ATM) from which the classical GSG and GMT models were recently derived in the literature. The intermediate ATM like effective action possesses some spinors resembling the higher grading fields of the ATM theory which have non-zero chirality. These fields are shown to disappear from the physical spectrum, thus providing a bag model like confinement mechanism and leading to the appearance of the massive fermions (solitons). The ordinary MT/SG duality turns out to be related to each SU(2) sub-group. The higher rank Lie algebra extension is also discussed.Comment: 22 pages, LaTex. Some misprints were corrected. Published in Eur.Phys J.

Sex‐specific activation of SK current by isoproterenol facilitates action potential triangulation and arrhythmogenesis in rabbit ventricles

Sex has a large influence on cardiac electrophysiological properties. Whether sex differences exist in apamin‐sensitive small conductance Ca2+‐activated K+ (SK) current (IKAS) remains unknown. We performed optical mapping, transmembrane potential, patch clamp, western blot and immunostaining in 62 normal rabbit ventricles, including 32 females and 30 males. IKAS blockade by apamin only minimally prolonged action potential (AP) duration (APD) in the basal condition for both sexes, but significantly prolonged APD in the presence of isoproterenol in females. Apamin prolonged APD at the level of 25% repolarization (APD25) more prominently than APD at the level of 80% repolarization (APD80), consequently reversing isoproterenol‐induced AP triangulation in females. In comparison, apamin prolonged APD to a significantly lesser extent in males and failed to restore the AP plateau during isoproterenol infusion. IKAS in males did not respond to the L‐type calcium current agonist BayK8644, but was amplified by the casein kinase 2 (CK2) inhibitor 4,5,6,7‐tetrabromobenzotriazole. In addition, whole‐cell outward IKAS densities in ventricular cardiomyocytes were significantly larger in females than in males. SK channel subtype 2 (SK2) protein expression was higher and the CK2/SK2 ratio was lower in females than in males. IKAS activation in females induced negative intracellular Ca2+–voltage coupling, promoted electromechanically discordant phase 2 repolarization alternans and facilitated ventricular fibrillation (VF). Apamin eliminated the negative Ca2+–voltage coupling, attenuated alternans and reduced VF inducibility, phase singularities and dominant frequencies in females, but not in males. We conclude that β‐adrenergic stimulation activates ventricular IKAS in females to a much greater extent than in males. IKAS activation plays an important role in ventricular arrhythmogenesis in females during sympathetic stimulation

On the Hydrogen Atom via Wigner-Heisenberg Algebra

We extend the usual Kustaanheimo-Stiefel $4D\to 3D$ mapping to study and discuss a constrained super-Wigner oscillator in four dimensions. We show that the physical hydrogen atom is the system that emerges in the bosonic sector of the mapped super 3D system.Comment: 14 pages, no figure. This work was initiated in collaboration with Jambunatha Jayaraman (In memory), whose advises and encouragement were fundamental. http://www.cbpf.b

Bogomol'nyi Equations of Maxwell-Chern-Simons vortices from a generalized Abelian Higgs Model

We consider a generalization of the abelian Higgs model with a Chern-Simons term by modifying two terms of the usual Lagrangian. We multiply a dielectric function with the Maxwell kinetic energy term and incorporate nonminimal interaction by considering generalized covariant derivative. We show that for a particular choice of the dielectric function this model admits both topological as well as nontopological charged vortices satisfying Bogomol'nyi bound for which the magnetic flux, charge and angular momentum are not quantized. However the energy for the topolgical vortices is quantized and in each sector these topological vortex solutions are infinitely degenerate. In the nonrelativistic limit, this model admits static self-dual soliton solutions with nonzero finite energy configuration. For the whole class of dielectric function for which the nontopological vortices exists in the relativistic theory, the charge density satisfies the same Liouville equation in the nonrelativistic limit.Comment: 30 pages(4 figures not included), RevTeX, IP/BBSR/93-6

Absence of cardiomyocyte differentiation following transplantation of adult cardiac-resident Sca-1+ cells into infarcted mouse hearts

Although several lines of evidence suggest that the glycosyl phosphatidylinositol-anchored cell surface protein Sca-1 marks cardiac-resident stem cells, a critical analysis of the literature raises some concerns regarding their cardiomyogenic potential.1 Here, isolated adult cardiac-resident Sca-1+ cells were engrafted into infarcted hearts and monitored for cardiomyogenic differentiation. Donor cells were prepared from ACT-EGFP; MHC-nLAC double-transgenic mice ([C57/Bl6J x DBA/2J]F1 genetic background; all procedures followed were in accordance with Institutional Guidelines). The ACT-EGFP transgene targets ubiquitous expression of an enhanced green fluorescent protein reporter, and the MHC-nLAC transgene targets cardiomyocyte-restricted expression of a nuclear-localized β-galactosidase reporter. Donor cell survival was monitored via EGFP fluorescence, while cardiomyogenic differentiation was monitored by reacting with the chromogenic β-galactosidase substrate 5-bromo-4-chloro-3-indolyl-β-D-galactoside (X-GAL), which gives rise to a blue product.2 Double-transgenic hearts were dispersed with Blendzyme and the resulting cells reacted with an APC-conjugated anti-Sca-1 antibody and a PE-conjugated cocktail of antibodies recognizing hematopoietic lineage markers.3 Sca-1+, EGFP+, lineage- cells were then isolated via fluorescence-activated cell sorting (FACS; characterization of the donor cells is provided in Figure 1A), and 100,000 cells were injected into the infarct border zone of non-transgenic [C57/Bl6J x DBA/2J]F1 mice immediately following permanent coronary artery occlusion

Some Recent Developments on Kink Collisions and Related Topics

We review recent works on modeling of dynamics of kinks in 1+1 dimensional $\phi^4$ theory and other related models, like sine-Gordon model or $\phi^6$ theory. We discuss how the spectral structure of small perturbations can affect the dynamics of non-perturbative states, such as kinks or oscillons. We describe different mechanisms, which may lead to the occurrence of the resonant structure in the kink-antikink collisions. We explain the origin of the radiation pressure mechanism, in particular, the appearance of the negative radiation pressure in the $\phi^4$ and $\phi^6$ models. We also show that the process of production of the kink-antikink pairs, induced by radiation is chaotic.Comment: 26 pages, 9 figures; invited chapter to "A dynamical perspective on the {\phi}4 model: Past, present and future", Eds. P.G. Kevrekidis and J. Cuevas-Maraver; Springer book class with svmult.cls include

Equivalence between free quantum particles and those in harmonic potentials and its application to instantaneous changes

This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedIn quantum physics the free particle and the harmonically trapped particle are arguably the most important systems a physicist needs to know about. It is little known that, mathematically, they are one and the same. This knowledge helps us to understand either from the viewpoint of the other. Here we show that all general time-dependent solutions of the free-particle Schrodinger equation can be mapped to solutions of the Schrodinger equation for harmonic potentials, both the trapping oscillator and the inverted `oscillator'. This map is fully invertible and therefore induces an isomorphism between both types of system, they are equivalent. A composition of the map and its inverse allows us to map from one harmonic oscillator to another with a different spring constant and different center position. The map is independent of the state of the system, consisting only of a coordinate transformation and multiplication by a form factor, and can be chosen such that the state is identical in both systems at one point in time. This transition point in time can be chosen freely, the wave function of the particle evolving in time in one system before the transition point can therefore be linked up smoothly with the wave function for the other system and its future evolution after the transition point. Such a cut-and-paste procedure allows us to describe the instantaneous changes of the environment a particle finds itself in. Transitions from free to trapped systems, between harmonic traps of different spring constants or center positions, or, from harmonic binding to repulsive harmonic potentials are straightforwardly modelled. This includes some time dependent harmonic potentials. The mappings introduced here are computationally more efficient than either state-projection or harmonic oscillator propagator techniques conventionally employed when describing instantaneous (non-adiabatic) changes of a quantum particle's environmentPeer reviewe

The Small Conductance Calcium Activated Potassium Current Modulates the Ventricular Escape Rhythm in Normal Rabbit Hearts

Background The apamin-sensitive small-conductance calcium-activated K (SK) current (IKAS) modulates automaticity of the sinus node; IKAS blockade by apamin causes sinus bradycardia. Objective To test the hypothesis that IKAS modulates ventricular automaticity. Methods We tested the effects of apamin (100 nM) on ventricular escape rhythms in Langendorff perfused rabbit ventricles with atrioventricular (AV) block (Protocol 1) and on recorded transmembrane action potential (TMP) of pseudotendons of superfused right ventricular (RV) endocardial preparations (Protocol 2). Results All preparations exhibited spontaneous ventricular escape rhythms. In Protocol 1, apamin decreased the atrial rate from 186.2±18.0 bpm to 163.8±18.7 bpm (N=6, p=0.006) but accelerated the ventricular escape rate from 51.5±10.7 to 98.2±25.4 bpm (p=0.031). Three preparations exhibited bursts of nonsustained ventricular tachycardia (NSVT) and pauses, resulting in repeated burst-termination pattern. In Protocol 2, apamin increased the ventricular escape rate from 70.2±13.1 to 110.1±2.2 bpm (p=0.035). Spontaneous phase 4 depolarization was recorded from the pseudotendons in 6 of 10 preparations at baseline and in 3 in the presence of apamin. There were no changes of phase 4 slope (18.37±3.55 vs. 18.93±3.26 mV/s, p=0.231, N=3), but the threshold of phase 0 activation (mV) reduced from -67.97±1.53 to -75.26±0.28 (p=0.034). Addition of JTV-519, a ryanodine receptor 2 (RyR2) stabilizer, in 5 preparations reduced escape rate back to baseline. Conclusions Contrary to its bradycardic effect in the sinus node, IKAS blockade by apamin accelerates ventricular automaticity and causes repeated NSVT in normal ventricles. RyR2 blockade reversed the apamin effects on ventricular automaticity