62 research outputs found

    Measurement of Viscosities of Liquids Saturated with Gases at High Pressures

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    Measurement of Viscosities of Liquids Saturated with Gases at High Pressures

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    Triviality and the (Supersymmetric) See-Saw

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    For the D=5 Majorana neutrino mass operator to have a see-saw ultraviolet completion that is viable up to the Planck scale, the see-saw scale is bounded above due to triviality limits on the see-saw couplings. For supersymmetric see-saw models, with realistic neutrino mass textures, we compare constraints on the see-saw scale from triviality bounds, with those arising from experimental limits on induced charged-lepton flavour violation, for both the CMSSM and for models with split supersymmetry.Comment: 27 pages, 7 figures, references adde

    Phase Equilibria in Hydrocarbon Systems. I. Methods and Apparatus

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    Phase Equilibria in Hydrocarbon Systems. II. Methane-Propane System

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    Tandem E2F Binding Sites in the Promoter of the p107 Cell Cycle Regulator Control p107 Expression and Its Cellular Functions

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    The retinoblastoma tumor suppressor (Rb) is a potent and ubiquitously expressed cell cycle regulator, but patients with a germline Rb mutation develop a very specific tumor spectrum. This surprising observation raises the possibility that mechanisms that compensate for loss of Rb function are present or activated in many cell types. In particular, p107, a protein related to Rb, has been shown to functionally overlap for loss of Rb in several cellular contexts. To investigate the mechanisms underlying this functional redundancy between Rb and p107 in vivo, we used gene targeting in embryonic stem cells to engineer point mutations in two consensus E2F binding sites in the endogenous p107 promoter. Analysis of normal and mutant cells by gene expression and chromatin immunoprecipitation assays showed that members of the Rb and E2F families directly bound these two sites. Furthermore, we found that these two E2F sites controlled both the repression of p107 in quiescent cells and also its activation in cycling cells, as well as in Rb mutant cells. Cell cycle assays further indicated that activation of p107 transcription during S phase through the two E2F binding sites was critical for controlled cell cycle progression, uncovering a specific role for p107 to slow proliferation in mammalian cells. Direct transcriptional repression of p107 by Rb and E2F family members provides a molecular mechanism for a critical negative feedback loop during cell cycle progression and tumorigenesis. These experiments also suggest novel therapeutic strategies to increase the p107 levels in tumor cells

    Pre-Micro RNA Signatures Delineate Stages of Endothelial Cell Transformation in Kaposi Sarcoma

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    MicroRNAs (miRNA) have emerged as key regulators of cell lineage differentiation and cancer. We used precursor miRNA profiling by a novel real-time QPCR method (i) to define progressive stages of endothelial cell transformation cumulating in Kaposi sarcoma (KS) and (ii) to identify specific miRNAs that serve as biomarkers for tumor progression. We were able to compare primary patient biopsies to well-established culture and mouse tumor models. Loss of mir-221 and gain of mir-15 expression demarked the transition from merely immortalized to fully tumorigenic endothelial cells. Mir-140 and Kaposi sarcoma–associated herpesvirus viral miRNAs increased linearly with the degree of transformation. Mir-24 emerged as a biomarker specific for KS

    Characterization of thrombospondin synthesis, secretion and cell surface expression by human tumor cells

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    Previous studies have shown that thrombospondin (TSP) is an adhesion factor for some human tumor cells. The previous studies have shown further that tumor cells which utilize TSP as an adhesion factor also synthesize it. This study continues the effort to understand how TSP production and expression are regulated in human tumor cells and the consequences of this for the cells. It is shown that differences among cell lines in their capacity to biosynthesize TSP are associated with differences in TSP specific mRNA levels. This indicates that biosynthesis is regulated at the transcriptional level. There is also a direct relationship between TSP biosynthesis and secretion into the culture medium and expression at the cell surface. The cells which are the most biosynthetically active secrete amounts of TSP into the culture medium that are sufficient to elicit a detectable response in the cell-substrate adhesion assay. The kinetics of TSP secretion by these cells are in accord with the kinetics of attachment and spreading of the same cells in the absence of exogenous adhesion factors. These data are consistent with the idea that endogenously produced TSP promotes the adhesion of the cells which synthesize it in an autocrine manner.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42595/1/10585_2005_Article_BF01753679.pd
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