U-Duality Invariance of the Four-dimensional Born-Infeld Theory

We calculate the Hamiltonian of a compactified D4-brane, with general fluxes and moduli, and find the BPS-mass. The results are invariant under the complete U-duality SO(5,5,Z).Comment: 9 pages, Late

Detection of chemotherapy-resistant patient-derived acute lymphoblastic leukemia clones in murine xenografts using cellular barcodes

Clonal heterogeneity fuels leukemia evolution, therapeutic resistance, and relapse. Upfront detection of therapy-res istant leukemia clones at diagnosis may allow adaptation of treatment and prevention of relapse, but this is hampered by a paucity of methods to identify and trace single leukemia-propagating cells and their clonal offspring. Here, we tested methods of cellular barcoding analysis, to trace the in vivo competitive dynamics of hundreds of patient-derived leukemia clones upon chemotherapy-mediated selective pressure. We transplanted Nod/Scid/Il2Rg(-/-) (NSG) mice with barcoded patient-derived or SupB15 acute lymphoblastic leukemia (ALL) cells and assessed clonal responses to dexamethasone, methotrexate, and vincristine, longitudinally and across nine anatomic locations. We illustrate that chemotherapy reduces clonal diversity in a drug-dependent manner. At end-stage disease, methotrexate-treated patientderived xenografts had significantly fewer clones compared with placebo-treated mice (100 +/- 10 vs. 160 +/- 15 clones, p = 0.0005), while clonal complexity in vincristineand dexamethasone-treated xenografts was unaffected (115 +/- 33 and 150 +/- 7 clones, p = NS). Using tools developed to assess differential gene expression, we determined whether these clonal patterns resulted from random clonal drift or selection. We identified 5 clones that were reproducibly enriched in methotrexate-treated patient-derived xenografts, suggestive of pre-existent resistance. Finally, we found that chemotherapymediated selection resulted in a more asymmetric distribution of leukemia clones across anatomic sites. We found that cellular barcoding is a powerful method to trace the clonal dynamics of human patient-derived leukemia cells in response to chemotherapy. In the future, integration of cellular barcoding with single-cell sequencing technology may allow in-depth characterization of therapy-resistant leukemia clones and identify novel targets to prevent relapse. (C) 2020 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc

Donor-to-Donor Heterogeneity in the Clonal Dynamics of Transplanted Human Cord Blood Stem Cells in Murine Xenografts

Umbilical cord blood (UCB) provides an alternative source of hematopoietic stem cells (HSCs) for allogeneic transplantation. Administration of sufficient donor HSCs is critical to restore recipient hematopoiesis and to maintain long-term polyclonal blood formation. However, due to lack of unique markers, the frequency of HSCs among UCB CD34(+) cells is the subject of ongoing debate, urging for reproducible strategies for their counting. Here, we used cellular barcoding to determine the frequency and clonal dynamics of human UCB HSCs and to determine how data analysis methods affect these parameters. We transplanted lentivirally barcoded CD34(+) cells from 20 UCB donors into Nod/Scid/IL2Ry(-/-) (NSG) mice (n = 30). Twelve recipients (of 8 UCB donors) engrafted with >1% GFP(+) cells, allowing for clonal analysis by multiplexed barcode deep sequencing. Using multiple definitions of clonal diversity and strategies for data filtering, we demonstrate that differences in data analysis can change clonal counts by several orders of magnitude and propose methods to improve their consistency. Using these methods, we show that the frequency of NSG-repopulating cells was low (median similar to 1 HSC/10(4) CD34(+) UCB cells) and could vary up to 10-fold between donors. Clonal patterns in blood became increasingly consistent over time, likely reflecting initial output of transient progenitors, followed by long-term HSCs with stable hierarchies. The majority of long-term clones displayed multilineage output, yet clones with lymphoid- or myeloid-biased output were also observed. Altogether, this study uncovers substantial interdonor and analysis-induced variability in the frequency of UCB CD34(+) clones that contribute to post-transplant hematopoiesis. As clone tracing is increasingly relevant, we urge for universal and transparent methods to count HSC clones during normal aging and upon transplantation. (C) 2019 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc

Purification and Ex Vivo Expansion of Fully Functional Salivary Gland Stem Cells

Hyposalivation often leads to irreversible and untreatable xerostomia. Salivary gland (SG) stem cell therapy is an attractive putative option to salvage these patients but is impeded by the limited availability of adult human tissue. Here, using murine SG cells, we demonstrate single-cell self-renewal, differentiation, enrichment of SG stem cells, and robust in vitro expansion. Dependent on stem cell marker expression, SG sphere-derived single cells could be differentiated in vitro into distinct lobular or ductal/lobular organoids, suggestive of progenitor or stem cell potency. Expanded cells were able to form miniglands/organoids containing multiple SG cell lineages. Expansion of these multipotent cells through serial passaging resulted in selection of a cell population, homogenous for stem cell marker expression (CD24hi/CD29hi). Cells highly expressing CD24 and CD29 could be prospectively isolated and were able to efficiently restore radiation-damaged SG function. Our approach will facilitate the use of adult SG stem cells for a variety of scientific and therapeutic purposes

Respiratory Syncytial Virus, Human Metapneumovirus, and Parainfluenza Virus Infections in Lung Transplant Recipients:A Systematic Review of Outcomes and Treatment Strategies

BACKGROUND: Respiratory syncytial virus (RSV), parainfluenza virus (PIV), and human metapneumovirus (hMPV) are increasingly associated with chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTR). This systematic review primarily aimed to assess outcomes of RSV/PIV/hMPV infections in LTR and secondarily to assess evidence regarding the efficacy of ribavirin. METHODS: Relevant databases were queried and study outcomes extracted using a standardized method and summarized. RESULTS: Nineteen retrospective and 12 prospective studies were included (total 1060 cases). Pooled 30-day mortality was low (0-3%), but CLAD progression 180-360 days postinfection was substantial (pooled incidences 19-24%) and probably associated with severe infection. Ribavirin trended toward effectiveness for CLAD prevention in exploratory meta-analysis (odds ratio [OR] 0.61, [0.27-1.18]), although results were highly variable between studies. CONCLUSIONS: RSV/PIV/hMPV infection was followed by a high CLAD incidence. Treatment options, including ribavirin, are limited. There is an urgent need for high-quality studies to provide better treatment options for these infections

Correction:Quantitative distribution of patient-derived leukemia clones in murine xenografts revealed by cellular barcodes

An amendment to this paper has been published and can be accessed via a link at the top of the paper.</p

The effect of COVID-19 on transplant function and development of CLAD in lung transplant patients:A multicenter experience

Background : Concerns have been raised on the impact of coronavirus disease (COVID-19) on lung transplant (LTx) patients. The aim of this study was to evaluate the transplant function pre- and post-COVID-19 in LTx patients. Methods : Data were retrospectively collected from LTx patients with confirmed COVID-19 from all 3 Dutch transplant centers, between February 2020 and September 2021. Spirometry results were collected pre-COVID-19, 3- and 6-months post infection. Results : Seventy-four LTx patients were included. Forty-two (57%) patients were admitted, 19 (26%) to the intensive care unit (ICU). The in-hospital mortality was 20%. Twelve out of 19 ICU patients died (63%), a further 3 died on general wards. Patients with available spirometry (78% at 3 months, 65% at 6 months) showed a significant decline in mean forced expiratory volume in 1 second (FEV1) (ΔFEV1 138 ± 39 ml, p = 0.001), and forced vital capacity (FVC) (ΔFVC 233 ±74 ml, p = 0.000) 3 months post infection. Lung function improved slightly from 3 to 6 months after COVID-19 (ΔFEV1 24 ± 38 ml; ΔFVC 100 ± 46 ml), but remained significantly lower than pre-COVID-19 values (ΔFEV1 86 ml ± 36 ml, p = 0.021; ΔFVC 117 ± 35 ml, p = 0.012). FEV1/FVC was > 0.70. Conclusions: In LTx patients COVID-19 results in high mortality in hospitalized patients. Lung function declined 3 months after infection and gradually improved at 6 months, but remained significantly lower compared to pre-COVID-19 values. The more significant decline in FVC than in FEV1 and FEV1/FVC > 70%, suggested a more restrictive pattern

Observing the Evolution of the Universe

How did the universe evolve? The fine angular scale (l>1000) temperature and polarization anisotropies in the CMB are a Rosetta stone for understanding the evolution of the universe. Through detailed measurements one may address everything from the physics of the birth of the universe to the history of star formation and the process by which galaxies formed. One may in addition track the evolution of the dark energy and discover the net neutrino mass. We are at the dawn of a new era in which hundreds of square degrees of sky can be mapped with arcminute resolution and sensitivities measured in microKelvin. Acquiring these data requires the use of special purpose telescopes such as the Atacama Cosmology Telescope (ACT), located in Chile, and the South Pole Telescope (SPT). These new telescopes are outfitted with a new generation of custom mm-wave kilo-pixel arrays. Additional instruments are in the planning stages.Comment: Science White Paper submitted to the US Astro2010 Decadal Survey. Full list of 177 author available at http://cmbpol.uchicago.ed