38 research outputs found
A large stellar evolution database for population synthesis studies. II. Stellar models and isochrones for an alpha-enhanced metal distribution
[Abridged] We present a large, new set of stellar evolution models and
isochrones for an alpha-enhanced metal distribution typical of Galactic halo
and bulge stars; it represents a homogeneous extension of our stellar model
library for a distribution already presented in Pietrinferni et al.(2004). The
effect of the alpha-element enhancement has been properly taken into account in
the nuclear network, opacity, equation of state and, for the first time, the
bolometric corrections, and color transformations. This allows us to avoid the
inconsistent use - common to all alpha-enhanced model libraries currently
available - of scaled-solar bolometric corrections and color transformations
for alpha-enhanced models and isochrones. We show how bolometric corrections to
magnitudes obtained for the U,B portion of stellar spectra for T_{eff}<=6500K,
are significantly affected by the metal mixture, especially at the higher
metallicities. We also provide complete sets of evolutionary models for
low-mass, He-burning stellar structures covering the whole metallicity range,
to enable synthetic horizontal branch simulations. We compare our database with
several widely used stellar model libraries from different authors, as well as
with various observed color magnitude and color-color diagrams (Johnson-Cousins
BVI and near infrared magnitudes, Stromgren colors) of Galactic field stars and
globular clusters. We also test our isochrones comparing integrated optical
colors and Surface Brightness Fluctuation magnitudes with selected globular
cluster data. We find a general satisfactory agreement with the empirical
constraints.Comment: 46 pages, 20 figures, ApJ in press, the whole database presented in
this paper can be foud at http://www.te.astro.it/BASTI/index.ph
Whole-Genome Sequencing Characterization of Virulence Profiles of Listeria monocytogenes Food and Human Isolates and In Vitro Adhesion/Invasion Assessment
none13sìListeria monocytogenes (Lm) is the causative agent of human listeriosis. Lm strains have
different virulence potential. For this reason, we preliminarily characterised via Whole-Genome
Sequencing (WGS) some Lm strains for their key genomic features and virulence-associated determinants,
assigning the clonal complex (CC). Moreover, the ability of the same strains to adhere to and
invade human colon carcinoma cell line Caco-2, evaluating the possible correspondence with their
genetic virulence profile, was also assessed. The clinical strains typed belonged to clonal complex
(CC)1, CC31, and CC101 and showed a very low invasiveness. The Lm strains isolated from food
were assigned to CC1, CC7, CC9, and CC121. All CC1 carried the hypervirulence pathogenicity
island LIPI-3 in addition to LIPI-1. Premature stop codons in the inlA gene were found only in Lm of
food origin belonging to CC9 and CC121. The presence of LIPI2_inlII was observed in all the CCs
except CC1. The CC7 strain, belonging to an epidemic cluster, also carried the internalin genes inlG
and inlL and showed the highest level of invasion. In contrast, the human CC31 strain lacked the
lapB and vip genes and presented the lowest level of invasiveness. In Lm, the genetic determinants
of hypo- or hypervirulence are not necessarily predictive of a cell adhesion and/or invasion ability
in vitro. Moreover, since listeriosis results from the interplay between host and virulence features of
the pathogen, even hypovirulent clones are able to cause infection in immunocompromised people.openGiuditta Fiorella Schiavano * , Collins Njie Ateba , Annalisa Petruzzelli , Veronica Mele ,
Giulia Amagliani , Fabrizia Guidi , Mauro De Santi , Francesco Pomilio , Giuliana Blasi ,
Antonietta Gattuso , Stefania Di Lullo , Elena Rocchegiani, Giorgio BrandiSchiavano, GIUDITTA FIORELLA; Njie Ateba, Collins; Petruzzelli, Annalisa; Mele, Veronica; Amagliani, Giulia; Guidi, Fabrizia; DE SANTI, Mauro; Pomilio, Francesco; Blasi, Giuliana; Gattuso, Antonietta; Di Lullo, Stefania; Rocchegiani, Elena; Brandi, Giorgi
Glutathione Depletion Is Linked with Th2 Polarization in Mice with a Retrovirus-Induced Immunodeficiency Syndrome, Murine AIDS: Role of Proglutathione Molecules as Immunotherapeutics
Injection of the LP-BM5 murine leukemia virus into mice causes murine AIDS, a disease characterized by many dysfunctions of immunocompetent cells. To establish whether the disease is characterized by glutathione imbalance, reduced glutathione (GSH) and cysteine were quantified in different organs. A marked redox imbalance, consisting of GSH and/or cysteine depletion, was found in the lymphoid organs, such as the spleen and lymph nodes. Moreover, a significant decrease in cysteine and GSH levels in the pancreas and brain, respectively, was measured at 5 weeks postinfection. The Th2 immune response was predominant at all times investigated, as revealed by the expression of Th1/Th2 cytokines. Furthermore, investigation of the activation status of peritoneal macrophages showed that the expression of genetic markers of alternative activation, namely, Fizz1, Ym1, and Arginase1, was induced. Conversely, expression of inducible nitric oxide synthase, a marker of classical activation of macrophages, was detected only when Th1 cytokines were expressed at high levels. In vitro studies revealed that during the very early phases of infection, GSH depletion and the downregulation of interleukin-12 (IL-12) p40 mRNA were correlated with the dose of LP-BM5 used to infect the macrophages. Treatment of LP-BM5-infected mice with N-(N-acetyl-L-cysteinyl)-S-acetylcysteamine (I-152), an N-acetyl-cysteine supplier, restored GSH/cysteine levels in the organs, reduced the expression of alternatively activated macrophage
markers, and increased the level of gamma interferon production, while it decreased the levels of Th2 cytokines, such as IL-4 and IL-5. Our findings thus establish a link between GSH deficiency and Th1/Th2 disequilibrium in LP-BM5 infection and indicate that I-152 can be used to restore the GSH level and a balanced Th1/Th2 response in infected mice
Transforming observational data and theoretical isochrones into the ACS/WFC Vega-mag system
We propose a zero-point photometric calibration of the data from the ACS/WFC
on board the Hubble Space Telescope, based on a spectrum of Vega and the most
up to date in-flight transmission curves of the camera. This calibration is
accurate at the level of a few hundredths of a magnitude. The main purpose of
this effort is to transform the entire set of evolutionary models by
Pietrinferni et al. (2004) into a simple observational photometric system for
ACS/WFC data, and make them available to the astronomical community. We provide
the zero points for the most used ACS/WFC bands, and give basic recipes for
calibrating both the observed data and the models.
We also present the Colour Magnitude Diagram (CMD) from ACS data of 5
Galactic globular clusters, spanning the metallicity range -2.2<[Fe/H]<-0.04,
and provide fiducial points representing their sequences from several
magnitudes below the turnoff to the red giant branch tip. The observed
sequences are compared with the models in the newly defined photometric system.Comment: 10 pages, 3 figures, 7 Tables. Accepted (2004 Dec 14) on M.N.R.A.
A large stellar evolution database for population synthesis studies. I. Scaled solar models and isochrones
We present a large and updated stellar evolution database for low-,
intermediate- and high-mass stars in a wide metallicity range, suitable for
studying Galactic and extragalactic simple and composite stellar populations
using population synthesis techniques. The stellar mass range is between
\sim0.5Mo and 10Mo with a fine mass spacing. The metallicity [Fe/H] comprises
10 values ranging from -2.27 to 0.40, with a scaled solar metal distribution.
The initial He mass fraction ranges from Y=0.245, for the more metal-poor
composition, up to 0.303 for the more metal-rich one, with Delta Y/Delta Z\sim
1.4. For each adopted chemical composition, the evolutionary models have been
computed without and with overshooting from the Schwarzschild boundary of the
convective cores during the central H-burning phase. The whole set of
evolutionary models can be used to compute isochrones in a wide age range, from
\sim30 Myr to \sim15Gyr. Both evolutionary tracks and isochrones are available
in several observational planes, employing updated set of bolometric
corrections and color-Te relations computed for this project. The number of
points along the models and the resulting isochrones is selected in such a way
that interpolation for intermediate metallicities not contained in the grid is
straightforward. We compare our isochrones with results from different stellar
evolution databases and perform some empirical tests for the reliability of our
models. Since this work is devoted to scaled solar compositions, we focus our
attention on the Galactic disk populations, employing multicolor photometry of
unevolved field MS stars with precise Hipparcos parallaxes, well-studied open
clusters and one eclipsing binary system with precise measurements of masses,
radii and [Fe/H] of both components.Comment: 57 pages, 26 figures (figs. 3, 4, 6 are at low resolution), ApJ in
press, the whole set of evolutionary results can be retrieved at
http://www.te.astro.it/BASTI/index.ph
Sea Urchin Granuloma
Sea urchin granuloma is a chronic focal response to the puncture of sea urchin spines, induced by the permanence of prickle remnants in the wound. Until recent years, it was thought to represent a foreign body reaction but, following the description, in 2001, of its several histologic forms, the spectrum of its likely pathogenetic mechanisms has widened to include the immune responses to different non-self antigens. Depending on individual reactivity, in most cases, a limited number of granulomas is observed, however numerous the punctures may be. We report a case with more than 200 lesions and a tuberculoid histologic pattern, indicative of an immune reaction
Centrifugal necrotic keratoacanthoma
Centrifugal necrotic keratoacanthoma is a quite rare variant of keratoacanthoma, with a locally aggressive behavior and no tendency to spontaneous involution. We report a typical case of the nasal-orbital region. Based on its clinical, histological and behavioral picture, centrifugal necrotic keratoacanthoma appears as variant of giant keratoacanthoma and can be regarded as an intermediate form in a spectrum where keratoacanthoma and overt squamous cell carcinoma represent the most benign and the most malignant end, respectively, as also highlighted by analogies between the two lesions recently reported in the field of molecular biology