199 research outputs found

    Accounting Problems Under the Excess Profits Tax

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    DNA vaccines based on subunits from pathogens have several advantages over other vaccine strategies. DNA vaccines can easily be modified, they show good safety profiles, are stable and inexpensive to produce, and the immune response can be focused to the antigen of interest. However, the immunogenicity of DNA vaccines which is generally quite low needs to be improved. Electroporation and co-delivery of genetically encoded immune adjuvants are two strategies aiming at increasing the efficacy of DNA vaccines. Here, we have examined whether targeting to antigen-presenting cells (APC) could increase the immune response to surface envelope glycoprotein (Env) gp120 from Human Immunodeficiency Virus type 1 (HIV- 1). To target APC, we utilized a homodimeric vaccine format denoted vaccibody, which enables covalent fusion of gp120 to molecules that can target APC. Two molecules were tested for their efficiency as targeting units: the antibody-derived single chain Fragment variable (scFv) specific for the major histocompatilibility complex (MHC) class II I-E molecules, and the CC chemokine ligand 3 (CCL3). The vaccines were delivered as DNA into muscle of mice with or without electroporation. Targeting of gp120 to MHC class II molecules induced antibodies that neutralized HIV-1 and that persisted for more than a year after one single immunization with electroporation. Targeting by CCL3 significantly increased the number of HIV-1 gp120-reactive CD8(+) T cells compared to non-targeted vaccines and gp120 delivered alone in the absence of electroporation. The data suggest that chemokines are promising molecular adjuvants because small amounts can attract immune cells and promote immune responses without advanced equipment such as electroporation.Funding Agencies|Research Council of Norway; Odd Fellow</p

    Establishment of a Replicating Plasmid in Rickettsia prowazekii

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    Rickettsia prowazekii, the causative agent of epidemic typhus, grows only within the cytosol of eukaryotic host cells. This obligate intracellular lifestyle has restricted the genetic analysis of this pathogen and critical tools, such as replicating plasmid vectors, have not been developed for this species. Although replicating plasmids have not been reported in R. prowazekii, the existence of well-characterized plasmids in several less pathogenic rickettsial species provides an opportunity to expand the genetic systems available for the study of this human pathogen. Competent R. prowazekii were transformed with pRAM18dRGA, a 10.3 kb vector derived from pRAM18 of R. amblyommii. A plasmid-containing population of R. prowazekii was obtained following growth under antibiotic selection, and the rickettsial plasmid was maintained extrachromosomally throughout multiple passages. The transformant population exhibited a generation time comparable to that of the wild type strain with a copy number of approximately 1 plasmid per rickettsia. These results demonstrate for the first time that a plasmid can be maintained in R. prowazekii, providing an important genetic tool for the study of this obligate intracellular pathogen

    A Novel Extracellular Hsp90 Mediated Co-Receptor Function for LRP1 Regulates EphA2 Dependent Glioblastoma Cell Invasion

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    Extracellular Hsp90 protein (eHsp90) potentiates cancer cell motility and invasion through a poorly understood mechanism involving ligand mediated function with its cognate receptor LRP1. Glioblastoma multiforme (GBM) represents one of the most aggressive and lethal brain cancers. The receptor tyrosine kinase EphA2 is overexpressed in the majority of GBM specimens and is a critical mediator of GBM invasiveness through its AKT dependent activation of EphA2 at S897 (P-EphA2(S897)). We explored whether eHsp90 may confer invasive properties to GBM via regulation of EphA2 mediated signaling.We find that eHsp90 signaling is essential for sustaining AKT activation, P-EphA2(S897), lamellipodia formation, and concomitant GBM cell motility and invasion. Furthermore, eHsp90 promotes the recruitment of LRP1 to EphA2 in an AKT dependent manner. A finding supported by biochemical methodology and the dual expression of LRP1 and P-EphA2(S897) in primary and recurrent GBM tumor specimens. Moreover, hypoxia mediated facilitation of GBM motility and invasion is dependent upon eHsp90-LRP1 signaling. Hypoxia dramatically elevated surface expression of both eHsp90 and LRP1, concomitant with eHsp90 dependent activation of src, AKT, and EphA2.We herein demonstrate a novel crosstalk mechanism involving eHsp90-LRP1 dependent regulation of EphA2 function. We highlight a dual role for eHsp90 in transducing signaling via LRP1, and in facilitating LRP1 co-receptor function for EphA2. Taken together, our results demonstrate activation of the eHsp90-LRP1 signaling axis as an obligate step in the initiation and maintenance of AKT signaling and EphA2 activation, thereby implicating this pathway as an integral component contributing to the aggressive nature of GBM

    Recent advances in the genetics of SDH-related paraganglioma and pheochromocytoma

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    The last 10 years have seen enormous progress in the field of paraganglioma and pheochromocytoma genetics. The identification of the first gene related to paraganglioma, SDHD, encoding a subunit of mitochondrial succinate dehydrogenase (SDH), was quickly followed by the identification of mutations in SDHC and SDHB. Very recently several new SDH-related genes have been discovered. The SDHAF2 gene encodes an SDH co-factor related to the function of the SDHA subunit, and is currently exclusively associated with head and neck paragangliomas. SDHA itself has now also been identified as a paraganglioma gene, with the recent identification of the first mutation in a patient with extra-adrenal paraganglioma. Another SDH-related co-factor, SDHAF1, is not currently known to be a tumor suppressor, but may shed some light on the mechanisms of tumorigenesis. An entirely novel gene associated with adrenal pheochromocytoma, TMEM127, suggests that other new paraganglioma susceptibility genes may await discovery. In addition to these recent discoveries, new techniques related to mutation analysis, including genetic analysis algorithms, SDHB immunohistochemistry, and deletion analysis by MLPA have improved the efficiency and accuracy of genetic analysis. However, many intriguing questions remain, such as the striking differences in the clinical phenotype of genes that encode proteins with an apparently very close functional relationship, and the lack of expression of SDHD and SDHAF2 mutations when inherited via the maternal line. Little is still known of the origins and causes of truly sporadic tumors, and the role of oxygen in the relationships between high-altitude, familial and truly sporadic paragangliomas remains to be elucidated

    Susceptibility of Pancreatic Beta Cells to Fatty Acids Is Regulated by LXR/PPARα-Dependent Stearoyl-Coenzyme A Desaturase

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    Chronically elevated levels of fatty acids-FA can cause beta cell death in vitro. Beta cells vary in their individual susceptibility to FA-toxicity. Rat beta cells were previously shown to better resist FA-toxicity in conditions that increased triglyceride formation or mitochondrial and peroxisomal FA-oxidation, possibly reducing cytoplasmic levels of toxic FA-moieties. We now show that stearoyl-CoA desaturase-SCD is involved in this cytoprotective mechanism through its ability to transfer saturated FA into monounsaturated FA that are incorporated in lipids. In purified beta cells, SCD expression was induced by LXR- and PPARα-agonists, which were found to protect rat, mouse and human beta cells against palmitate toxicity. When their SCD was inhibited or silenced, the agonist-induced protection was also suppressed. A correlation between beta cell-SCD expression and susceptibility to palmitate was also found in beta cell preparations isolated from different rodent models. In mice with LXR-deletion (LXRβ-/- and LXRαβ-/-), beta cells presented a reduced SCD-expression as well as an increased susceptibility to palmitate-toxicity, which could not be counteracted by LXR or PPARα agonists. In Zucker fatty rats and in rats treated with the LXR-agonist TO1317, beta cells show an increased SCD-expression and lower palmitate-toxicity. In the normal rat beta cell population, the subpopulation with lower metabolic responsiveness to glucose exhibits a lower SCD1 expression and a higher susceptibility to palmitate toxicity. These data demonstrate that the beta cell susceptibility to saturated fatty acids can be reduced by stearoyl-coA desaturase, which upon stimulation by LXR and PPARα agonists favors their desaturation and subsequent incorporation in neutral lipids

    Determination of the number of J/ψ events with J/ψ → inclusive decays

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    Two-photon widths of the χ c0,2 states and helicity analysis for χ c2→γγ

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    Based on a data sample of 106×106 ψ ′ events collected with the BESIII detector, the decays ψ ′→γχ c0,2, χ c0,2→γγ are studied to determine the two-photon widths of the χ c0,2 states. The two-photon decay branching fractions are determined to be B(χ c0→γγ)=(2. 24±0.19±0.12±0.08)×10 -4 and B(χ c2→γγ)=(3.21±0.18±0. 17±0.13)×10 -4. From these, the two-photon widths are determined to be Γ γγ(χ c0)=(2. 33±0.20±0.13±0.17)keV, Γ γγ(χ c2)=(0.63±0.04±0. 04±0.04)keV, and R=Γ γγ(χ c2)/ Γ γγ(χ c0)=0.271±0. 029±0.013±0.027, where the uncertainties are statistical, systematic, and those from the PDG B(ψ ′→γχ c0,2) and Γ(χ c0,2) errors, respectively. The ratio of the two-photon widths for helicity λ=0 and helicity λ=2 components in the decay χ c2→γγ is measured for the first time to be f 0/2=Γγγλ= 0(χ c2)/Γγγλ=2(χ c2)=0. 00±0.02±0.02. © 2012 American Physical Society.published_or_final_versio

    Search for a light exotic particle in J/psi radiative decays

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    Using a data sample containing 1.06x10^8 psi' events collected with the BESIII detector at the BEPCII electron-positron collider, we search for a light exotic particle X in the process psi' -> pi^+ pi^- J/psi, J/psi -> gamma X, X -> mu^+ mu^-. This light particle X could be a Higgs-like boson A^0, a spin-1 U boson, or a pseudoscalar sgoldstino particle. In this analysis, we find no evidence for any mu^+mu^- mass peak between the mass threshold and 3.0 GeV/c^2. We set 90%-confidence-level upper limits on the product-branching fractions for J/psi -> gamma A^0, A^0 -> mu^+ mu^- which range from 4x10^{-7} to 2.1x10^{-5}, depending on the mass of A^0, for M(A^0)<3.0 GeV/c^2. Only one event is seen in the mass region below 255 MeV/c^2 and this has a mu^+mu^- mass of 213.3 MeV/c^2 and the product branching fraction upper limit 5x10^{-7}.Comment: 7 pages, 3 figures, submitted to Physical Review
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