Soluble CD40 ligand can replace the normal T cell-derived CD40 ligand signal to B cells in T cell-dependent activation

We have constructed a soluble chimeric fusion protein between the mouse CD8 alpha chain and the mouse CD40 T cell ligand. This protein binds to both human and mouse B cells. By itself it induced a modest degree of B cell proliferation, but together with anti-immunoglobulin (anti-Ig) antibody it greatly stimulated B cell proliferation, as determined by both [3H]thymidine uptake and increase in cell numbers. These data are evidence that the CD40 ligand on T cells provides a signal that drives B cell proliferation. This signal is synergistic with that delivered by anti-Ig antibody

Simulated Annealing Clusterization Algorithm for Studying the Multifragmentation

We present the details of the numerical realization of the recently advanced algorithm developed to identify the fragmentation in heavy ion reactions. This new algorithm is based on the Simulated Annealing method and is dubbed as Simulated Annealing Clusterization Algorithm [SACA]. We discuss the different parameters used in the Simulated Annealing method and present an economical set of the parameters which is based on the extensive analysis carried out for the central and peripheral collisions of Au-Au, Nb-Nb and Pb-Pb. These parameters are crucial for the success of the algorithm. Our set of optimized parameters gives the same results as the most conservative choice, but is very fast. We also discuss the nucleon and fragment exchange processes which are very important for the energy minimization and finally present the analysis of the reaction dynamics using the new algorithm. This algorithm is can be applied whenever one wants to identify which of a given number of constituents form bound objects.Comment: 36 pages, 15 figures, submitted to Journal of Computational Physic

Impact of endocytosis and lysosomal acidification on the toxicity of copper oxide nano-and microsized particles: Uptake and gene expression related to oxidative stress and the DNA damage response

The toxicity of the copper oxide nanoparticles (CuO NP) has been attributed to the so-called “Trojan horse”-type mechanism, relying on the particle uptake and extensive intracellular release of copper ions, due to acidic pH in the lysosomes. Nevertheless, a clear distinction between extra- and intracellular-mediated effects is still missing. Therefore, the impact of the endocytosis inhibitor hydroxy-dynasore (OH-dyn), as well as bafilomycin A1 (bafA1), inhibiting the vacuolar type H+-ATPase (V-ATPase), on the cellular toxicity of nano- and microsized CuO particles, was investigated in BEAS 2 B cells. Selected endpoints were cytotoxicity, copper uptake, glutathione (GSH) levels, and the transcriptional DNA damage and (oxidative) stress response using the high-throughput reverse transcription quantitative polymerase chain reaction (RT-qPCR). OH-dyn markedly reduced intracellular copper accumulation in the cases of CuO NP and CuO MP; the modulation of gene expression, induced by both particle types affecting especially HMOX1, HSPA1A, MT1X, SCL30A1, IL8 and GADD45A, were completely abolished. BafA1 lowered the intracellular copper concentration in case of CuO NP and strongly reduced transcriptional changes, while any CuO MP-mediated effects were not affected by bafA1. In conclusion, the toxicity of CuO NP depended almost exclusively upon dynamin-dependent endocytosis and the intracellular release of redox-active copper ions due to lysosomal acidification, while particle interactions with cellular membranes appeared to be not relevant

Kinematisch vollständige und zustands-selektive Untersuchung der stoßinduzierten Einfachionisation von Lithium

Die Untersuchung stoßinduzierter atomarer Fragmentationsprozesse ermöglicht Einblicke in die Dynamik korrelierter Mehr-Teilchen-Systeme, deren theoretische Beschreibung bis heute eine der fundamentalsten Herausforderungen der Physik darstellt. Den sensitivsten Test theoretischer Modelle erlauben kinematisch vollständige Experimente, bei denen die Impulsbilanz aller beteiligter Teilchen vermessen wird. Bei der stoßinduzierten Ionisation von Helium wurden dabei überraschende Diskrepanzen zwischen Theorie und Experiment gefunden. In Rahmen dieser Arbeit wurde zum ersten Mal eine neuartige experimentelle Technik, ein sogenanntes MOTReMi, bestehend aus einem Reaktionsmikroskop (ReMi) in Kombination mit einer magneto-optischen Falle (MOT) zur Präparation und Kühlung des Targets, verwendet und erlaubt eine Verbesserung der Rückstoßionen-Impulsauflösung verglichen mit früheren Experimenten um den Faktor 2-3. Als Target wurde Lithium aufgrund seiner interessanten elektronischen Struktur gewählt. In den in dieser Arbeit durchgeführten Experimenten am Test-Speicherring TSR wurde die Einfachionisation von Lithium im Stoß mit 6 MeV Protonen sowie mit 24 MeV O8+ -Ionen studiert, was im Rahmen einer perturbativen Beschreibung einer sehr kleinen bzw. mittleren Störung entspricht. Dabei gelang es erstmals, vollständig differentiellen Wirkungsquerschnitte für ein Target anders als Helium zu vermessen, und darüber hinaus die Ionisation eines zustands-präparierten und polarisierten Targets zu untersuchen. Es wurden Charakteristika in den vollständig differentiellen Daten gefunden, die auf Eigenschaften der Anfangszustandswellenfunktionen des Targets zurückgeführt werden

Experimental Indications for the Response of the Spectators to the Participant Blast

Precise momentum distributions of identified projectile fragments, formed in the reactions 238U + Pb and 238U + Ti at 1 A GeV, are measured with a high-resolution magnetic spectrometer. With increasing mass loss, the velocities first decrease as expected from previously established systematics, then level off, and finally increase again. Light fragments are on the average even faster than the projectiles. This finding is interpreted as the response of the spectators to the participant blast. The re-acceleration of projectile spectators is sensitive to the nuclear mean field and provides a new tool for investigating the equation of state of nuclear matter.Comment: 7 pages, 3 figures, background information on http://www-wnt.gsi.de/kschmidt

Ion-lithium collision dynamics studied with an in-ring MOTReMi

We present a novel experimental tool allowing for kinematically complete studies of break-up processes of laser-cooled atoms. This apparatus, the 'MOTReMi', is a combination of a magneto-optical trap (MOT) and a Reaction Microscope (ReMi). Operated in an ion-storage ring, the new setup enables to study the dynamics in swift ion-atom collisions on an unprecedented level of precision and detail. In first experiments on collisions with 1.5 MeV/amu O$^{8+}$-Li the pure ionization of the valence electron as well as ionization-excitation of the lithium target has been investigated

Comparison of Experimental and Theoretical Fully Differential Cross Sections for Single Ionization of the 2s and 2p States of Li By O⁸⁺ Ions

This paper presents a full three-dimensional (3D) comparison between experiment and theory for 24 MeV O8+ single ionization of the 2s ground state of lithium and the 2p excited state. Two theoretical approximations are examined: the three-body continuum distorted-wave (3DW) and three-body continuum distorted-wave-eikonal initial state (3DW-EIS). Normally, there is a significant difference between these two approaches and the 3DW-EIS is in much better agreement with experiment. In this case, there is very little difference between the two approaches and both are in very good agreement with experiment. For the excited 2p state, the 3D cross sections would exhibit a mirror symmetry about the scattering plane if all three magnetic sublevels were excited in equal proportions. For the present experiment, the 2p+1 (m=+1) sublevel is dominantly excited (quantization axis is the incident beam direction) and for this case there is a magnetic dichroism which is observed both experimentally and theoretically