University of Siena

About: University of Siena is a education organization based out in Siena, Italy. It is known for research contribution in the topics: Population & Cancer. The organization has 12179 authors who have published 33334 publications receiving 1008287 citations. The organization is also known as: Università degli studi di Siena & Universita degli studi di Siena.

Sialic Acid: A Preventable Signal for Pneumococcal Biofilm Formation, Colonization, and Invasion of the Host

Abstract: The correlation between carbohydrate availability, pneumococcal biofilm formation, nasopharyngeal colonization, and invasion of the host has been investigated. Of a series of sugars, only sialic acid (i.e., N-acetylneuraminic acid) enhanced pneumococcal biofilm formation in vitro, at concentrations similar to those of free sialic acid in human saliva. In a murine model of pneumococcal carriage, intranasal inoculation of sialic acid significantly increased pneumococcal counts in the nasopharynx and instigated translocation of pneumococci to the lungs. Competition of both sialic acid-dependent phenotypes was found to be successful when evaluated using the neuraminidase inhibitors DANA (i.e., 2,3-didehydro-2-deoxy-N-acetylneuraminic acid), zanamivir, and oseltamivir. The association between levels of free sialic acid on mucosae, pneumococcal colonization, and development of invasive disease shows how a host-derived molecule can influence a colonizing microbe and also highlights a molecular mechanism that explains the epidemiologic correlation between respiratory infections due to neuraminidase-bearing viruses and bacterial pneumonia. The data provide a new paradigm for the role of a host compound in infectious diseases and point to new treatment strategies.

Riboflavin-UVA-induced corneal collagen cross-linking in pediatric patients.

Abstract: PURPOSE Evaluation of stability and functional response after riboflavin-UVA–induced cross-linking in a population of patients younger than 18 years with progressive keratoconus after 36 months of follow-up. METHODS Prospective nonrandomized phase II open trial conducted at the Department of Ophthalmology, Siena University, Italy. The "Siena CXL Pediatrics" trial involved 152 patients aged 18 years or younger (10–18 years) with clinical and instrumental evidence of keratoconus progression. The population was divided into 2 groups according to corneal thickness (>450 and 450 μm) and +0.14 and +0.15 Snellen lines, respectively, in the thinner group (corneal thickness <450 μm). Patients in the latter group already showed a better and faster functional recovery than the thicker group at 3-month follow-up. Topographic results showed statistically significant improvement in K readings and asymmetry index values. Coma reduction was also statistically significant. CONCLUSIONS The study demonstrated significant and rapid functional improvement in pediatric patients younger than 18 years with progressive keratoconus, undergoing riboflavin-UVA–induced cross-linking. In pediatric age, a good functional response and keratoconus stability was obtained after corneal cross-linking in a 36-month follow-up.

Pollen carbohydrates and water content during development, presentation, and dispersal: a short review

Abstract: Pollen accumulates starch reserves during development and the final stage of ripening. Before the anther opens, starch is totally or partially converted to pectins, glucose, fructose, sucrose, and to some unknown polysaccharides. Pollen is exposed to dispersing agents in an arrested developmental state which differs according to pollen water content. Pollen is classified as partially dehydrated or partially hydrated. The final water content may be reached before or after anther opening. Especially during exposure and dispersal, partially dehydrated pollen may interconvert soluble and insoluble reserves, modifying internal turgor pressure and hindering water loss or gain. Partially hydrated pollen is commonly devoid of mechanisms to conserve viability in time but has the advantage of quickly emitting pollen tubes on reaching the stigma.

Design, synthesis, and biological evaluation of sirtinol analogues as class III histone/protein deacetylase (Sirtuin) inhibitors.

Abstract: In a search for potent inhibitors of class III histone/protein deacetylases (sirtuins), a series of sirtinol analogues have been synthesized and the degree of inhibition was assessed in vitro using recombinant yeast Sir2, human SIRT1, and human SIRT2 and in vivo with a yeast phenotypic assay. Two analogues, namely, 3- and 4-[(2-hydroxy-1-naphthalenylmethylene)amino]-N-(1-phenylethyl)benzamide (i.e., m- and p-sirtinol), were 2- to 10-fold more potent than sirtinol against human SIRT1 and SIRT2 enzymes. In yeast in vivo assay, these two small molecules were as potent as sirtinol. Compounds lacking the 2-hydroxy group at the naphthalene moiety or bearing several modifications at the benzene 2‘-position of the aniline portion (carbethoxy, carboxy, and cyano) were 1.3−13 times less potent than sirtinol, whereas the 2‘-carboxamido analogue was totally inactive. Both (R)- and (S)-sirtinol had similar inhibitory effects on the yeast and human enzymes, demonstrating no enantioselective inhibitory effect.

Proton-proton elastic scattering at the LHC energy of \chem{\sqrt{s} = 7\,TeV}

Abstract: Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at √ s = 7 TeV in dedicated runs with the Roman Pot detectors placed as close as seven times the transverse beam size (σbeam) from the outgoing beams. After careful study of the accelerator optics and the detector alignment, |t|, the square of four-momentum transferred in the elastic scattering process, has been determined with an uncertainty of δt = 0.1 GeV p |t|. In this letter, first results of the differential cross-section are presented covering a |t|-range from 0.36 to 2.5 GeV 2 . The differential cross-section in the range 0.36 < |t| < 0.47 GeV 2 is described by an exponential with a slope parameter B =( 23.6 ± 0.5 stat ± 0.4 syst )G eV −2 , followed by a significant diffractive minimum at |t| =( 0.53 ± 0.01 stat ± 0.01 syst )G eV 2 .F or|t|-values larger than ∼ 1. 5G eV 2 , the cross-section exhibits a power law behaviour with an exponent of −7.8 ± 0.3 stat ± 0.1 syst . When compared to predictions based on the different available models, the data show a strong discriminative power despite the small t-range covered. open access Copyright c EPLA, 2011