University of Perugia

About: University of Perugia is a education organization based out in Perugia, Umbria, Italy. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 13365 authors who have published 39516 publications receiving 1265601 citations. The organization is also known as: Universitá degli Studi di Perugia & Universita degli Studi di Perugia.

Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era

Abstract: We report on the gamma-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average LAT gamma-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 +/- 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of 2), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 +/- 0.14, and the softest one is 2.51 +/- 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3GeV. In this paper, we also present the first results from the 4.5-month-long multifrequency campaign (2009 March 15 - August 1) on Mrk 501, which included the VLBA, Swift, RXTE, MAGIC and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton model. In the framework of this model, we find that the dominant emission region is characterized by a size <~ 0.1 pc (comparable within a factor of few to the size of the partially-resolved VLBA core at 15-43 GHz), and that the total jet power (~10^{44} erg s^{-1}) constitutes only a small fraction (~10^{-3}) of the Eddington luminosity. The energy distribution of the freshly-accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3GeV-10TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks.

Endothelial dysfunction in young patients with rheumatoid arthritis and low disease activity

Abstract: Background: Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease. Endothelial dysfunction represents the earliest stage of atherosclerosis. Objective: To evaluate the influence of chronic inflammatory state on endothelial function in patients with RA by measuring endothelial reactivity in young patients with RA with low disease activity and without traditional cardiovascular risk factors. Methods: Brachial flow mediated vasodilatation (FMV), assessed by non-invasive ultrasound, was evaluated in 32 young to middle aged patients with RA (age ⩽59 years), with DAS28 ⩽3.2 and without overt cardiovascular disease, and in 28 age and sex matched controls. Results: Mean (SD) FMV was significantly lower in patients than in controls (3.2 (1.3)% v 5.7 (2.0)%; p r = −0.45, p r = −0.44, p r = −0.47, p r = −0.40, p Conclusions: Young to middle aged patients with RA with low disease activity, free from cardiovascular risk factors and overt cardiovascular disease, have an altered endothelial reactivity that seems to be primarily related to the disease associated chronic inflammatory condition.

Myeloid cell differentiation arrest by miR-125b-1 in myelodysplasic syndrome and acute myeloid leukemia with the t(2;11)(p21;q23) translocation

Abstract: Most chromosomal translocations in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) involve oncogenes that are either up-regulated or form part of new chimeric genes. The t(2;11)(p21;q23) translocation has been cloned in 19 cases of MDS and AML. In addition to this, we have shown that this translocation is associated with a strong up-regulation of miR-125b (from 6- to 90-fold). In vitro experiments revealed that miR-125b was able to interfere with primary human CD34(+) cell differentiation, and also inhibited terminal (monocytic and granulocytic) differentiation in HL60 and NB4 leukemic cell lines. Therefore, miR-125b up-regulation may represent a new mechanism of myeloid cell transformation, and myeloid neoplasms carrying the t(2;11) translocation define a new clinicopathological entity.

Chemistry and biological activity of natural and synthetic prenyloxycoumarins.

Abstract: Prenyloxycoumarins and prenyloxyfuranocoumarins (isopentenyloxy-, geranyloxy-, linear and cyclic sesquiterpenyloxy compounds and their biosynthetic derivatives) represent a family of secondary metabolites that have been considered for years just as intermediates of other coumarin-based compounds. Only in the last two decades these secondary metabolites have been recognized as interesting and valuable biologically active natural products. Up to now more than 160 compounds have been isolated from plants mainly belonging to the families of Rutaceae and Umbelliferae, comprising common edible vegetables and fruits like lemons, oranges and grapefruits. In view of the biological activity of some natural prenyloxycoumarins, very recently syntheses of structurally related analogs aimed to establish detailed structure-activity relationships have also been carried out. Many of the isolated prenyloxy- and prenyloxyfuranocoumarins and their semisynthetic derivatives were shown to exert in vitro and in vivo remarkable antitumoral, anti-inflammatory and anti-viral effects. The object of this review is to examine in detail the different types of prenyloxycoumarins and prenyloxyfuranocoumarins from the chemical, phytochemical and biological point of view.