31 research outputs found

    Vacuum polarization for lukewarm black holes

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    We compute the renormalized expectation value of the square of a quantum scalar field on a Reissner-Nordström–de Sitter black hole in which the temperatures of the event and cosmological horizons are equal (“lukewarm” black hole). Our numerical calculations for a thermal state at the same temperature as the two horizons indicate that this renormalized expectation value is regular on both the event and cosmological horizons. We are able to show analytically, using an approximation for the field modes near the horizons, that this is indeed the case

    Some general properties of the renormalized stress-energy tensor for static quantum states on (n+1)-dimensional spherically symmetric black holes

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    We study the renormalized stress-energy tensor (RSET) for static quantum states on (n+1)-dimensional, static, spherically symmetric black holes. By solving the conservation equations, we are able to write the stress-energy tensor in terms of a single unknown function of the radial co-ordinate, plus two arbitrary constants. Conditions for the stress-energy tensor to be regular at event horizons (including the extremal and ``ultra-extremal'' cases) are then derived using generalized Kruskal-like co-ordinates. These results should be useful for future calculations of the RSET for static quantum states on spherically symmetric black hole geometries in any number of space-time dimensions.Comment: 9 pages, no figures, RevTeX4, references added, accepted for publication in General Relativity and Gravitatio

    Blood Supply to the Human Spinal Cord. II. Imaging and Pathology

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    The blood supply of the spinal cord is a complex system based on multilevel sources and anastomoses. Diseases often affect this vascular supply and imaging has been developed that better investigates these structures. The authors review the literature regarding pathology and imaging modalities for the blood supply of the spinal cord. Knowledge of the disease processes and imaging modalities used to investigate these arterial lesions of the spinal cord will assist the clinician when treating patients with spinal cord lesions

    Spatially restricted drivers and transitional cell populations cooperate with the microenvironment in untreated and chemo-resistant pancreatic cancer

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    Pancreatic ductal adenocarcinoma is a lethal disease with limited treatment options and poor survival. We studied 83 spatial samples from 31 patients (11 treatment-naïve and 20 treated) using single-cell/nucleus RNA sequencing, bulk-proteogenomics, spatial transcriptomics and cellular imaging. Subpopulations of tumor cells exhibited signatures of proliferation, KRAS signaling, cell stress and epithelial-to-mesenchymal transition. Mapping mutations and copy number events distinguished tumor populations from normal and transitional cells, including acinar-to-ductal metaplasia and pancreatic intraepithelial neoplasia. Pathology-assisted deconvolution of spatial transcriptomic data identified tumor and transitional subpopulations with distinct histological features. We showed coordinated expression of TIGIT in exhausted and regulatory T cells and Nectin in tumor cells. Chemo-resistant samples contain a threefold enrichment of inflammatory cancer-associated fibroblasts that upregulate metallothioneins. Our study reveals a deeper understanding of the intricate substructure of pancreatic ductal adenocarcinoma tumors that could help improve therapy for patients with this disease

    Antagonizing Integrin β3 Increases Immunosuppression in Cancer

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    Integrin β3 is critical for tumor invasion, neoangiogenesis, and inflammation, making it a promising cancer target. However, preclinical and clinical data of integrin β3 antagonists have demonstrated no benefit or worse outcomes. We hypothesized that integrin β3 could affect tumor immunity and evaluated tumors in mice with deletion of integrin β3 in macrophage lineage cells (β3KOM). β3KOM mice had increased melanoma and breast cancer growth with increased tumor-promoting M2 macrophages and decreased CD8+ T cells. Integrin β3 antagonist, cilengitide, also enhanced tumor growth and increased M2 function. We uncovered a negative feedback loop in M2 myeloid cells, wherein integrin β3 signaling favored STAT1 activation, an M1-polarizing signal, and suppressed M2-polarizing STAT6 activation. Finally, disruption of CD8+ T cells, macrophages, or macrophage integrin β3 signaling blocked the tumor-promoting effects of integrin β3 antagonism. These results suggest that effects of integrin β3 therapies on immune cells should be considered to improve outcomes. Cancer Res; 76(12); 3484–95. ©2016 AACR

    Consensus guidelines for the use and interpretation of angiogenesis assays

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    The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference

    The Sorting Receptor SorCS1 Regulates Trafficking of Neurexin and AMPA Receptors

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    The formation, function, and plasticity of synapses require dynamic changes in synaptic receptor composition. Here, we identify the sorting receptor SorCS1 as a key regulator of synaptic receptor trafficking. Four independent proteomic analyses identify the synaptic adhesion molecule neurexin and the AMPA glutamate receptor (AMPAR) as major proteins sorted by SorCS1. SorCS1 localizes to early and recycling endosomes and regulates neurexin and AMPAR surface trafficking. Surface proteome analysis of SorCS1-deficient neurons shows decreased surface levels of these, and additional, receptors. Quantitative in vivo analysis of SorCS1-knockout synaptic proteomes identifies SorCS1 as a global trafficking regulator and reveals decreased levels of receptors regulating adhesion and neurotransmission, including neurexins and AMPARs. Consequently, glutamatergic transmission at SorCS1-deficient synapses is reduced due to impaired AMPAR surface expression. SORCS1 mutations have been associated with autism and Alzheimer disease, suggesting that perturbed receptor trafficking contributes to synaptic-composition and -function defects underlying synaptopathies.publisher: Elsevier articletitle: The Sorting Receptor SorCS1 Regulates Trafficking of Neurexin and AMPA Receptors journaltitle: Neuron articlelink: http://dx.doi.org/10.1016/j.neuron.2015.08.007 content_type: article copyright: Copyright © 2015 Elsevier Inc. All rights reserved.status: publishe

    The ADAMTS1 protease gene is required for mammary tumor growth and metastasis

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    A disintegrin and metalloprotease with thrombospondin motifs protein 1 (ADAMTS1) is a protease commonly up-regulated in metastatic carcinoma. Its overexpression in cancer cells promotes experimental metastasis, but whether ADAMTS1 is essential for metastatic progression is unknown. To address this question, we investigated mammary cancer progression and spontaneous metastasis in the MMTV-PyMT mouse mammary tumor model in Adamts1 knockout mice. Adamts1(-/-)/PyMT mice displayed significantly reduced mammary tumor and lung metastatic tumor burden and increased survival, compared with their wild-type and heterozygous littermates. Histological examination revealed an increased proportion of tumors with ductal carcinoma in situ and a lower proportion of high-grade invasive tumors in Adamts1(-/-)/PyMT mice, compared with Adamts1(+/+)/PyMT mice. Increased apoptosis with unaltered proliferation and vascular density in the Adamts1(-/-)/PyMT tumors suggested that reduced cell survival accounts for the lower tumor burden in ADAMTS1-deficient mice. Furthermore, Adamts1(-/-) tumor stroma had significantly lesser amounts of proteolytically cleaved versican and increased numbers of CD45(+) leukocytes. Characterization of immune cell gene expression indicated that cytotoxic cell activation was increased in Adamts1(-/-) tumors, compared with Adamts1(+/+) tumors. This finding is supported by significantly elevated IL-12(+) cell numbers in Adamts1(-/-) tumors. Thus, in vivo ADAMTS1 may promote mammary tumor growth and progression to metastasis in the PyMT model and is a potential therapeutic target to prevent metastatic breast cancer.Carmela Ricciardelli, Kate M. Frewin, Izza de Arao Tan, Elizabeth D. Williams, Kenneth Opeskin, Melanie A. Pritchard, Wendy V. Ingman, and Darryl L. Russellhttp://www.elsevier.com/wps/find/journaldescription.cws_home/724906/description#descriptio

    Transcriptomic Analysis of Tail Regeneration in the Lizard <i>Anolis carolinensis</i> Reveals Activation of Conserved Vertebrate Developmental and Repair Mechanisms

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    <div><p>Lizards, which are amniote vertebrates like humans, are able to lose and regenerate a functional tail. Understanding the molecular basis of this process would advance regenerative approaches in amniotes, including humans. We have carried out the first transcriptomic analysis of tail regeneration in a lizard, the green anole <i>Anolis carolinensis</i>, which revealed 326 differentially expressed genes activating multiple developmental and repair mechanisms. Specifically, genes involved in wound response, hormonal regulation, musculoskeletal development, and the Wnt and MAPK/FGF pathways were differentially expressed along the regenerating tail axis. Furthermore, we identified 2 microRNA precursor families, 22 unclassified non-coding RNAs, and 3 novel protein-coding genes significantly enriched in the regenerating tail. However, high levels of progenitor/stem cell markers were not observed in any region of the regenerating tail. Furthermore, we observed multiple tissue-type specific clusters of proliferating cells along the regenerating tail, not localized to the tail tip. These findings predict a different mechanism of regeneration in the lizard than the blastema model described in the salamander and the zebrafish, which are anamniote vertebrates. Thus, lizard tail regrowth involves the activation of conserved developmental and wound response pathways, which are potential targets for regenerative medical therapies.</p></div
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