Photonic measurements of the longitudinal expansion dynamics in Heavy-Ion collisions

Due to the smallness of the electromagnetic coupling, photons escape from the hot and dense matter created in an heavy-ion collision at all times, in contrast to hadrons which are predominantly emitted in the final freeze-out phase of the evolving system. Thus, the thermal photon yield carries an imprint from the early evolution. We suggest how this fact can be used to gain information about where between the two limiting cases of Bjorken (boost-invariant expansion) and Landau (complete initial stopping and re-expansion) hydrodynamics the actual evolution can be found. We argue that both the rapidity dependence of the photon yield and photonic HBT radii are capable of answering this question.Comment: 10 pages, 3 figure

Thema - 1. Herstellung von HPV-16 rekombinanten Pflanzenviren für die Produktion viraler Gene in Leguminosen : 2. Modulation einer HPV-16-DNA-Vakzine

Im ersten Teil dieser Arbeit wurde versucht basierend auf einem Pflanzen-Virus-Vektorsystem verschiedene HPV16 rekombinante Viren herzustellen. Als Träger der HPV16-Sequenzen wurde die RNA-2 des Cowpea Mosaic Virus verwendet. Ziel war die billige Herstellungsweise einer anti-HPV16-Vakzine in Pflanzen (Vigna unguiculata) im großen Maßstab. Zu diesem Zweck wurden die HPV16-Gene L1 und E7 in das CPMV-Vektorsystem einkloniert und mit zwei unterschiedlichen Methoden in Pflanzen appliziert. Die ersten Experimente wurden mit der HPV16-rekombinanten cDNA-2 (RNA-2) mittels der mechanischen Inokulation durchgeführt. Mit dieser Methode konnte allerdings nur mit den Kontroll-Konstrukten (cDNA-2, cDNA-2-GFP) eine systemische CPMV-Infektion an Hand der Symptome beobachtet werden. Alle anderen Experimente mit den rekombinanten Konstrukten (HPV16L1) schlugen fehl. Auch ein effektiveres Inokulationssystem (Agrobakterien-Inokulation) resultierte abgesehen von den Kontroll-Konstrukten in keinem positiven Ergebnis. Innerhalb der oben beschriebenen Experimente sollte der Einfluss des Pflanzen-Kodon-optimierten HPV16E7 auf die Protein-Expression untersucht werden. Dies konnte allerdings aufgrund der negativen Ergebnisse in den Pflanzen nicht analysiert werden. Aus diesem Grund wurde der Einfluss des „Codon Usage“, allerdings mit den humanisierten HPV16-Genen E7 und L1 in DNA-Immunisierungs-Experimenten weiterverfolgt. Unterschiedlich modifizierte HPV16-DNA-Konstrukte wurden als DNA-Vakzine intramuskulär in Mäuse appliziert und mittels Elispot und Zytotoxizitätstest die zelluläre Immunantwort analysiert. In allen Experimenten konnte gezeigt werden, dass die Humanisierung der HPV16-Gene den größten Einfluss auf die Immunogenität hat und dass die zusätzliche Fusion der Kozak-Sequenz am 5´-Ende der HPV16E7-Sequenzen eher einen geringen Einfluss ausübte. Als Hauptursache für die verbesserte Immunogenität der humanisierten E7-Konstrukte, im Vergleich mit dem unmodifizierten E7-Wild-Typ-Gen, wurde die erhöhte Translation und damit die verstärkte E7-Protein-Expression vermutet. Um diese Hypothese zu bestätigen, wurden die modifizierten E7-Konstrukte in transienten Transfektion-Experimenten (293T-Zellen) analysiert. Vergleicht man nun die Daten aus den DNA-Immunisierungen und den Transfektionen, so erkennt man eine direkte Korrelation der verstärkten Expression in vitro und einer ebenso verbesserten Immunogenität in vivo. Dies gilt allerdings nur für die zelluläre Immunantwort und nicht für die humorale (ähnliche niedrige Antikörper)

Nuclear staining and relative distance for quantifying epidermal differentiation in biomarker expression profiling

<p>Abstract</p> <p>Background</p> <p>The epidermal physiology results from a complex regulated homeostasis of keratinocyte proliferation, differentiation and death and is tightly regulated by a specific protein expression during cellular maturation. Cellular <it>in silico </it>models are considered a promising and inevitable tool for the understanding of this complex system. Hence, we need to incorporate the information of the differentiation dependent protein expression in cell based systems biological models of tissue homeostasis. Such methods require measuring tissue differentiation quantitatively while correlating it with biomarker expression intensities.</p> <p>Results</p> <p>Differentiation of a keratinocyte is characterized by its continuously changing morphology concomitant with its movement from the basal layer to the surface, leading to a decreased average nuclei density throughout the tissue. Based thereon, we designed and evaluated three different mathematical measures (nuclei based, distance based, and joint approach) for quantifying differentiation in epidermal keratinocytes. We integrated them with an immunofluorescent staining and image analysis method for tissue sections, automatically quantifying epidermal differentiation and measuring the corresponding expression of biomarkers. When studying five well-known differentiation related biomarkers in an epidermal neck sample only the resulting biomarker profiles incorporating the relative distance information of cells to the tissue borders (distance based and joint approach) provided a high-resolution view on the whole process of keratinocyte differentiation. By contrast, the inverse nuclei density approach led to an increased resolution at early but heavily decreased resolution at late differentiation. This effect results from the heavy non-linear decay of DAPI intensity per area, probably caused by cytoplasmic growth and chromatin decondensation. In the joint approach this effect could be compensated again by incorporating distance information.</p> <p>Conclusion</p> <p>We suppose that key mechanisms regulating tissue homeostasis probably depend more on distance information rather than on nuclei reorganization. Concluding, the distance approach appears well suited for comprehensively observing keratinocyte differentiation.</p

Identification of Zirconia Particle Uptake in Human Osteoblasts by ToF-SIMS Analysis and Particle-Size Effects on Cell Metabolism

As the use of zirconia-based nano-ceramics is rising in dentistry, the examination of possible biological effects caused by released nanoparticles on oral target tissues, such as bone, is gaining importance. The aim of this investigation was to identify a possible internalization of differently sized zirconia nanoparticles (ZrNP) into human osteoblasts applying Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), and to examine whether ZrNP exposure affected the metabolic activity of the cells. Since ToF-SIMS has a low probing depth (about 5 nm), visualizing the ZrNP required the controlled erosion of the sample by oxygen bombardment. This procedure removed organic matter, uncovering the internalized ZrNP and leaving the hard particles practically unaffected. It was demonstrated that osteoblasts internalized ZrNP within 24 h in a size-dependent manner. Regarding the cellular metabolic activity, metabolization of alamarBlue by osteoblasts revealed a size- and time-dependent unfavorable effect of ZrNP, with the smallest ZrNP exerting the most pronounced effect. These findings point to different uptake efficiencies of the differently sized ZrNP by human osteoblasts. Furthermore, it was proven that ToF-SIMS is a powerful technique for the detection of zirconia-based nano/microparticles that can be applied for the cell-based validation of clinically relevant materials at the nano/micro scale

Mechano-transduction in periodontal ligament cells identifies activated states of MAP-kinases p42/44 and p38-stress kinase as a mechanism for MMP-13 expression

<p>Abstract</p> <p>Background</p> <p>Mechano-transduction in periodontal ligament (PDL) cells is crucial for physiological and orthodontic tooth movement-associated periodontal remodelling. On the mechanistic level, molecules involved in this mechano-transduction process in PDL cells are not yet completely elucidated.</p> <p>Results</p> <p>In the present study we show by western blot (WB) analysis and/or indirect immunofluorescence (IIF) that mechanical strain modulates the amount of the matrix metalloproteinase MMP-13, and induces non-coherent modulation in the amount and activity of signal transducing molecules, such as FAK, MAP-kinases p42/44, and p38 stress kinase, suggesting their mechanistic role in mechano-transduction. Increase in the amount of FAK occurs concomitant with increased levels of the focal contact integrin subunits β3 and β1, as indicated by WB or optionally by IIF. By employing specific inhibitors, we further identified p42/44 and p38 in their activated, i.e. phosphorylated state responsible for the expression of MMP-13. This finding may point to the obedience in the expression of this MMP as extracellular matrix (ECM) remodelling executioner from the activation state of mechano-transducing molecules. mRNA analysis by pathway-specific RT-profiler arrays revealed up- and/or down-regulation of genes assigning to MAP-kinase signalling and cell cycle, ECM and integrins and growth factors. Up-regulated genes include for example focal contact integrin subunit α3, MMP-12, MAP-kinases and associated kinases, and the transcription factor c-fos, the latter as constituent of the AP1-complex addressing the MMP-13 promotor. Among others, genes down-regulated are those of COL-1 and COL-14, suggesting that strain-dependent mechano-transduction may transiently perturbate ECM homeostasis.</p> <p>Conclusions</p> <p>Strain-dependent mechano-/signal-transduction in PDL cells involves abundance and activity of FAK, MAP-kinases p42/44, and p38 stress kinase in conjunction with the amount of MMP-13, and integrin subunits β1 and β3. Identifying the activated state of p42/44 and p38 as critical for MMP-13 expression may indicate the mechanistic contribution of mechano-transducing molecules on executioners of ECM homeostasis.</p

A matter of origin - identification of SEMA3A, BGLAP, SPP1 and PHEX as distinctive molecular features between bone site-specific human osteoblasts on transcription level

In oral and maxillofacial bone reconstruction, autografts from the iliac crest represent the gold standard due to their superior clinical performance, compared to autografts derived from other extraoral regions. Thus, the aim of our study was to identify putative differences between osteoblasts derived from alveolar (hOB-A) and iliac crest (hOB-IC) bone of the same donor (nine donors) by means of their molecular properties in 2D and 3D culture. We thereby focused on the gene expression of biomarkers involved in osteogenic differentiation, matrix formation and osteoclast modulation. Furthermore, we examined the transcriptional response to Vit.D3 in hOB-A and hOB-IC. Our results revealed different modulation modes of the biomarker expression in osteoblasts, namely cell origin/bone entity-dependent, and culture configuration- and/or time-dependent modulations. SEMA3A, SPP1, BGLAP and PHEX demonstrated the strongest dependence on cell origin. With respect to Vit.D3-effects, BGLAP, SPP1 and ALPL displayed the highest Vit.D3-responsiveness. In this context we demonstrated that the transcriptional Vit.D3-response concerning SPP1 and ALPL in human osteoblasts depended on the cell origin. The results indicate a higher bone remodeling activity of iliac crest than alveolar osteoblasts and support the growing evidence that a high osteoclast activity at the host-/donor bone interface may support graft integration