72 research outputs found
Stellar populations in the dwarf spheroidal galaxy Leo I
We present a detailed study of the color magnitude diagram (CMD) of the dwarf
spheroidal galaxy Leo I, based on archival Hubble Space Telescope data. Our
photometric analysis, confirming previous results on the brighter portion of
the CMD, allow us to obtain an accurate sampling of the stellar populations
also at the faint magnitudes corresponding to the Main Sequence. By adopting a
homogeneous and consistent theoretical scenario for both hydrogen and central
helium-burning evolutionary phases, the various features observed in the CMD
are interpreted and reliable estimations for both the distance modulus and the
age(s) for the main stellar components of Leo I are derived. More in details,
from the upper luminosity of the Red Giant Branch and the lower luminosity of
the Subgiant Branch we simultaneously constrain the galaxy distance and the age
of the oldest stellar population in Leo I. In this way we obtain a distance
modulus (m-M)_V=22.000.15 mag and an age of 10--15 Gyr or 9--13 Gyr,
adopting a metallicity Z=0.0001 and 0.0004, respectively. The reliability of
this distance modulus has been tested by comparing the observed distribution of
the Leo I anomalous Cepheids in the period-magnitude diagram with the predicted
boundaries of the instability strip, as given by convective pulsating models.Comment: 19 pages, 3 tables, 14 figures To be published in A
Collective awareness platforms and digital social innovation mediating consensus seeking in problem situations
In this paper we show the results of our studies carried out in the framework of the European Project SciCafe2.0 in the area of Participatory Engagement models. We present a methodological approach built on participative engagements models and holistic framework for problem situation clarification and solution impacts assessment. Several online platforms for social engagement have been analysed to extract the main patterns of participative engagement. We present our own experiments through the SciCafe2.0 Platform and our insights from requirements elicitation
Transforming growth factor-β regulates the splicing pattern of fibronectin messenger RNA precursor
AbstractFibronectin (FN) polymorphism is caused by alternative splicing patterns in at least three regions (ED-A, ED-B and IIICS) of the primary transcript of a single gene. Using monoclonal antibodies, we previously demonstrated that transforming growth factor-β (TGF-β) preferentially increases the accumulation of the FN isoforms containing the ED-A sequence in cultured normal human fibroblasts [Balza et al., (1988) FEBS Lett. 228, 42-44]. To determine the basis of this effect, we have examined through S1 nuclease analysis, the levels of ED-A- and ED-B-containing mRNAs in cultured normal human skin flbroblasts before and after TGF-β treatment. These experiments have shown that TGF-β increases the relative amount of m-RNA for ED-A- and ED-B-containing FN isoforms. These data demonstrate that a growth factor may regulate the splicing pattern of a pre-mRNA
Toxic organic contaminants in airborne particles: levels, potential sources and risk assessment
In the last years, many studies have focused on risk assessment of exposure of workers
to airborne particulate matter (PM). Several studies indicate a strong correlation between PM and
adverse health outcomes, as a function of particle size. In the last years, the study of atmospheric
particulate matter has focused more on particles less than 10 m or 2.5 m in diameter; however,
recent studies identify in particles less than 0.1 m the main responsibility for negative cardiovascular
effects. The present paper deals with the determination of 66 organic compounds belonging to six
different classes of persistent organic pollutants (POPs) in the ultrafine, fine and coarse fractions of
PM (PM < 0.1 m; 0.1 < PM < 2.5 mand 2.5 < PM < 10 m) collected in three outdoor workplaces and
in an urban outdoor area. Data obtained were analyzed with principal component analysis (PCA),
in order to underline possible correlation between sites and classes of pollutants and characteristic
emission sources. Emission source studies are, in fact, a valuable tool for both identifying the type
of emission source and estimating the strength of each contamination source, as useful indicator of
environment healthiness. Moreover, both carcinogenic and non-carcinogenic risks were determined
in order to estimate human health risk associated to study sites. Risk analysis was carried out
evaluating the contribution of pollutant distribution in PM size fractions for all the sites. The results
highlighted significant differences between the sites and specific sources of pollutants related to work
activities were identified. In all the sites and for all the size fractions of PM both carcinogenic and
non-carcinogenic risk values were below acceptable and safe levels of risks recommended by the
regulatory agencies
Alternative splicing of the angiogenesis associated extra-domain B of fibronectin regulates the accessibility of the B-C loop of the type III repeat 8
BACKGROUND: Fibronectin (FN) is a multi-domain molecule involved in many cellular processes, including tissue repair, embryogenesis, blood clotting, and cell migration/adhesion. The biological activities of FN are mediated by exposed loops located mainly at the interdomain interfaces that interact with various molecules such as, but not only, integrins. Different FN isoforms arise from the alternative splicing of the pre-mRNA. In malignancies, the splicing pattern of FN pre-mRNA is altered; in particular, the FN isoform containing the extra-domain B (ED-B), a complete FN type III repeat constituted by 91 residues, is undetectable in normal adult tissues, but exhibits a much greater expression in fetal and tumor tissues, and is accumulated around neovasculature during angiogenic processes, thus making ED-B one of the best markers and targets of angiogenesis. The functions of ED-B are still unclear; however, it has been postulated that the insertion of an extra-domain such as ED-B modifies the domain-domain interface and may unmask loops that are otherwise cryptic, thus giving FN new potential activities. METHODOLOGY: We used the mAb C6, which reacts with ED-B containing FN, but not with ED-B-free FN and various recombinant FN fragments containing mutations, to precisely localize the epitopes recognized by the mAb C6. CONCLUSION: We formally demonstrated that the inclusion of the alternatively spliced angiogenesis-associated ED-B leads to the unmasking of the FNIII 8 B-C loop that is cryptic in FN molecules lacking ED-B. Thus, the mAb C6, in addition to providing a new reagent for angiogenesis targeting, represents a new tool for the study of the potential biological functions of the B-C loop of the repeat FNIII 8 that is unmasked during angiogenic processes
The immunological basis of tumor therapy by targeted delivery of TNFa to tumor vessels
ISSN:1742-469
Use of uteroglobin for the engineering of polyvalent, polyspecific fusion proteins
We report a novel strategy to engineer and express stable and soluble human recombinant polyvalent/polyspecific fusion proteins. The procedure is based on the use of a central skeleton of uteroglobin, a small and very soluble covalently linked homodimeric protein that is very resistant to proteolytic enzymes and to pH variations. Using a human recombinant antibody (scFv) specific for the angiogenesis marker domain B of fibronectin, interleukin 2, and an scFv able to neutralize tumor necrosis factor-α, we expressed various biologically active uteroglobin fusion proteins. The results demonstrate the possibility to generate monospecific divalent and tetravalent antibodies, immunocytokines, and dual specificity tetravalent antibodies. Furthermore, compared with similar fusion proteins in which uteroglobin was not used, the use of uteroglobin improved properties of solubility and stability. Indeed, in the reported cases it was possible to vacuum dry and reconstitute the proteins without any aggregation or loss in protein and biological activity
A novel human fibronectin cryptic sequence unmasked by the insertion of the angiogenesis-associated extra type III domain B
Targeted delivery of tumor necrosis factor-alpha to tumor vessels induces a therapeutic T cell-mediated immune response that protects the host against syngeneic tumors of different histologic origin
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