ALBERT

Beschreibung: We report on the development of a three-axis absolute vector magnetometer suited for mobile operation in the Earth’s magnetic field. It is based on low critical temperature dc superconducting quantum interference devices (LTS dc SQUIDs) with sub-micrometer sized cross-type Josephson junctions and exhibits a white noise level of about 10 fT/Hz 1/2 . The width of superconducting strip lines is restricted to less than 6 μ m in order to avoid flux trapping during cool-down in magnetically unshielded environment. The long-term stability of the flux-to-voltage transfer coefficients of the SQUID electronics is investigated in detail and a method is presented to significantly increase their reproducibility. We further demonstrate the long-term operation of the setup in a magnetic field varying by about 200 μ T amplitude without the need for recalibration.

Beschreibung: We present a new technique for the statistical evaluation of the Tully–Fisher relation (TFR) using spectral line stacking. This technique has the potential to extend TFR observations to lower masses and higher redshifts than possible through a galaxy-by-galaxy analysis. It further avoids the need for individual galaxy inclination measurements. To quantify the properties of stacked H i emission lines, we consider a simplistic model of galactic discs with analytically expressible line profiles. Using this model, we compare the widths of stacked profiles with those of individual galaxies. We then follow the same procedure using more realistic mock galaxies drawn from the S 3 -SAX model (a derivative of the Millennium simulation). Remarkably, when stacking the apparent H i lines of galaxies with similar absolute magnitude and random inclinations, the width of the stack is very similar to the width of the deprojected (= corrected for inclination) and dedispersed (= after removal of velocity dispersion) input lines. Therefore, the ratio between the widths of the stack and the deprojected/dedispersed input lines is approximately constant – about 0.93 – with very little dependence on the gas dispersion, galaxy mass, galaxy morphology and shape of the rotation curve. Finally, we apply our technique to construct a stacked TFR using H i Parkes All-Sky Survey (HIPASS) data which already has a well-defined TFR based on individual detections. We obtain a B -band TFR with a slope of –8.5 ± 0.4 and a K -band relation with a slope of –11.7 ± 0.6 for the HIPASS data set which is consistent with the existing results.

Beschreibung: A new ultra-low temperature experiment including a superconducting vector magnet has been developed for soft x-ray absorption spectroscopy experiments at third generation synchrotron light sources. The sample is cooled below 50 mK by a cryogen free 3 He- 4 He dilution refrigerator. At the same time, magnetic fields of up to ±7 T in the horizontal direction and ±0.5 T in the vertical direction can be applied by a superconducting vector magnet. The setup allows to study ex situ and in situ prepared samples, offered by an attached UHV preparation chamber with load lock. The transfer of the prepared samples between the preparation section and the dilution refrigerator is carried out under cryogenic temperatures. First commissioning studies have been carried out at the Variable Polarization XUV Beamline P04 at PETRA III and the influence of the incident photon beam to the sample temperature has been studied.

Beschreibung: Approximately 25% of childhood acute lymphoblastic leukemias carry the ETV6/RUNX1 fusion gene. Despite their excellent initial treatment response, up to 20% of patients relapse. To gain insight into the relapse mechanisms, we analyzed single nucleotide polymorphism arrays for DNA copy number aberrations (CNAs) in 18 matched diagnosis and relapse leukemias. CNAs were more abundant at relapse than at diagnosis (mean 12.5 vs 7.5 per case; P = .01) with 5.3 shared on average. Their patterns revealed a direct clonal relationship with exclusively new aberrations at relapse in only 21.4%, whereas 78.6% shared a common ancestor and subsequently acquired distinct CNA. Moreover, we identified recurrent, mainly nonoverlapping deletions associated with glucocorticoid-mediated apoptosis targeting the Bcl2 modifying factor (BMF) (n = 3), glucocorticoid receptor NR3C1 (n = 4), and components of the mismatch repair pathways (n = 3). Fluorescence in situ hybridization screening of additional 24 relapsed and 72 nonrelapsed ETV6/RUNX1-positive cases demonstrated that BMF deletions were significantly more common in relapse cases (16.6% vs 2.8%; P = .02). Unlike BMF deletions, which were always already present at diagnosis, NR3C1 and mismatch repair aberrations prevailed at relapse. They were all associated with leukemias, which poorly responded to treatment. These findings implicate glucocorticoid-associated drug resistance in ETV6/RUNX1-positive relapse pathogenesis and therefore might help to guide future therapies.

Beschreibung: Abstract 1214 Immune thrombocytopenia (ITP) is the most common acquired thrombocytopenia in children. Typically, external triggers as infections or vaccinations cause the rise of antibodies that crossreact with antigens expressed on the platelet surface. These anti-platelet antibodies are mostly directed against glycoprotein complexes GPIIb/IIIa or GPIb/IX/V, resulting in an increased turnover of antibody-decorated platelets which are then sequestered by the reticuloendothelial system. Recently, it has been suggested that thrombocytopenia might also be due to an insufficient platelet production as serum of some patients with ITP can impair the maturation of CD34+ hematopoietic stem cells to bone marrow megakaryocytes (MKs) in vitro or abrogate the formation of proplatelets in an in vitro culture system. The accelerated platelet turnover demands the generation of platelets de novo. Bone marrow smears often reveal normal or slightly increased MKs, although they seem to be smaller and of altered morphology. However, very little is known about the consequences of anti-platelet antibodies on bone marrow MKs in vivo and in situ. Here, we took advantage of a simple animal model of passive ITP by single or multiple intraperitoneal injections of an anti-GPIb antibody into mice. MKs were evaluated by multi-color immunofluorescence histology on whole femur sections in a modified staining procedure that bypasses decalcification. MK numbers on day 3 were doubled in response to a single injection and tripled on day 8 when mice were injected additionally on day 3 and 7. In these mice platelet counts were up to 2000/nL on day 10, indicating the power to produce platelets. MK area per section was transiently upregulated on day 3 in single injected mice and quadrupled after multiple injections on day 8 before shrinking below norm on day 14. Staining with an anti-rat IgG antibody showed that the antibody was present on MKs within the bone marrow several hours to days after injection. The signal was present for 5 days and no antibody was detected on day 7. MKs had an overall normal morphology and showed no signs of apoptosis or DNA blebbing. All MKs analyzed were negative for TdT in a classical TUNEL assay, indicating that there were no single strand breaks. As platelet counts rose markedly while the antibody was still present on the MK surface, we sought to identify whether the pool of MKs is expanded or formed de novo. To address this, mice where fed with nucleotide analogue EdU for up to 12 days and femur sections stained with Click-It-647 reagent to stain for newly incorporated DNA while mice were treated with anti-platelet antibody or isotype control. We found EdU-positive MKs after 12 days in control isotype-injected mice indicating the de novo formation from hematopoietic stem cells. In antibody-injected mice, newly formed MKs were negative or stained weakly for EdU on day 12, suggesting that they arise partially from an existing pool of progenitors. Finally, we analyzed platelet formation in vivo by imaging of the cranial bone marrow of GPIIb-eYFP-heterozygous mice. The depletion antibody was labeled with Atto-590-fluorophore and injected hours before imaging. Vasculature was counterstained by Quantum dots. We found that MKs residing at the bone marrow were decorated with the antibody and released pre- and proplatelets into the vasculature, indicating that platelet biogenesis can occur in the presence of anti-platelet antibodies on MKs. Our data thus provide novel insight into the pathomechanism of platelet production in patients with ITP. Disclosures: No relevant conflicts of interest to declare.

Beschreibung: Acute lymphoblastic leukemia (ALL) is the most common malignancy in childhood. While improved multi-agent chemotherapy regimens with individualized risk stratification have led to increased survival rates of approximately 80 percent, 20 percent of patients respond poorly to therapy or relapse. Therefore, novel therapeutic avenues are urgently needed to improve treatment outcome, overcome resistance and reduce side effects. Failure to undergo cell death represents a key survival mechanism of cancer cells and results in drug resistance and clonal escape. Since inhibitor of apoptosis proteins (IAPs) are often overexpressed in malignant cells and their overexpression correlates with inferior survival rates, they provide an attractive molecular target for therapeutic intervention. Small molecule inhibitors have been developed that act as SMAC mimetics (SMs) to counteract the cell death inhibitory function of IAPs. SMs can activate and/or modulate cell death pathways, and are currently being evaluated in clinical trials. Their successful therapeutic implementation requires identification of patients who could benefit from a SM-based treatment regimen ideally before start of therapy. Here, we analyzed the intrinsic activity of two monovalent (AT406 and LCL161) and two bivalent (Birinapant or BV6) SMs on 29 unselected patient-derived pediatric precursor B-cell (BCP)-ALL samples and identified a subset of BCP-ALL primografts to be sensitive to SM treatment (n=8). When we compared gene expression of SM-sensitive (n=8) and SM-insensitive (n=6) patient-derived BCP-ALL samples, we identified a characteristic gene expression signature with 127 differentially regulated genes, amongst them upregulation of TNFRSF1A (TNFR1) in the SM-sensitive subset. In line with previous reports, we confirmed a critical role of the TNF/TNFR1-axis for SM-induced cell death in BCP-ALL by functional analysis. Expression of TNFRSF1A alone, however, did not correlate with sensitivity to SM-induced cell death indicating that TNFR1 is not the only factor regulating cell fate decisions in response to SM treatment. To identify potential biomarker genes for prediction of patient response to SM monotherapy in BCP-ALL, we compared differentially regulated genes of SM responders and non-responders from our cohort with data from a published cohort. Interestingly, we found 4 genes to overlap between these two cohorts. Of these 4 genes TSPAN7, FAM69C, and TNFRSF1A were upregulated whereas MTX2 was downregulated in SM-sensitive samples. The signature identified may reflect a particular TNF network. Analysis of expression levels of these 4 genes in BCP-ALL cell lines (Nalm6, Reh, UoCB6 and RS4;11) revealed that Reh cells, sensitive to SM-induced cell death, exhibited the biomarker profile of primograft sensitivity, i.e. upregulation of TSPAN7, FAM69C, TNFRSF1A and downregulation of MTX2. Nalm6 cells resembled the expression pattern of SM-insensitive samples with a downregulation of TSPAN7, FAM69C, TNFRSF1A and an upregulation of MTX2 and were resistant to SM-induced cell death. RS4;11 and UoCB6 cells showed no pattern. Based on these findings we hypothesized that the respective expression patterns of TSPAN7, FAM69C, TNFRSF1A and MTX2 could predict sensitivity to SMs. An extended screen of additional primary BCP-ALL samples for their expression levels of TSPAN7, FAM69C, TNFRSF1A and MTX2 and response to SMs substantiated this hypothesis. In summary, the subset of primary BCP-ALL samples with sensitivity to SMs is characterized by a gene signature with MTX2 low and TSPAN7, FAM69C and TNFRSF1A high. By using this expression profile, sensitivity to SMs in BCP-ALL could be identified in cell lines and additional primografts. Based on these results, we suggest the identified gene expression pattern as a biomarker for selecting patients to be treated by SM monotherapy in clinical trials. Disclosures No relevant conflicts of interest to declare.

Beschreibung: Omic BON is a thematic Biodiversity Observation Network under the Group on Earth Observations Biodiversity Observation Network (GEO BON), focused on coordinating the observation of biomolecules in organisms and the environment. Our founding partners include representatives from national, regional, and global observing systems; standards organizations; and data and sample management infrastructures. By coordinating observing strategies, methods, and data flows, Omic BON will facilitate the co-creation of a global omics meta-observatory to generate actionable knowledge. Here, we present key elements of Omic BON's founding charter and first activities.