170,312 research outputs found
A case study on possible radiological contamination in the Lo Uttaro landfill site (Caserta, Italy)
No full textThe prevention of radioactive pollution is a primary objective of environmental protection codes in the operation of solid waste landfill activities. Several studies have demonstrated the effectiveness of radiological monitoring of the main constituents of urban landfill waste. The present contribution reports on an investigation plan carried out to evaluate the possible radiological contamination in the municipal landfill Lo Uttaro, district of Caserta (Italy). The investigation focused primarily on the perimeter area of the landfill in order to assess the possible impact on the surrounding population. The results of measurements of the equivalent dose rate along the perimeter of the landfill show average values lower than the population dose limit due to natural background radiation. Several samples of soil, groundwater and leachate representative of the subsoil of the study area were collected and the radionuclides were measured by gamma spectrometry. The results of these measurements show the absence of artificial radionuclides, except for small amounts of 137Cs due to nuclear disasters occurring in the last 50 years on Earth, and the mere presence of 40K and other natural radionuclides belonging to natural radioactive chains of 238U, 235U and 232Th
The AGROVOC Linked Dataset
No full textBorn in the early eighties as a multilingual authority file of agricultural index terms, AGROVOC has steadily evolved these last thirty years, moving to an electronic version around the year 2000 and shortly thereafter embracing the Semantic Web. Today AGROVOC is a SKOS-XL concept scheme published as Linked Open Data cloud, containing links (as well as backlinks) and references to many other Linked Datasets in the LOD cloud. In this paper we provide a brief historical summary of AGROVOC and detail its specification as a Linked Dataset
X-ray absorption spectroscopy: a powerful tool for structural studies of molecules involved in the pathogenesis of neurodegenerative diseases
No full textQuesta tesi descrive l’applicazione della spettroscopia di assorbimento dei raggi X allo studio di sistemi biologici che sono particolarmente interessanti per la loro rilevanza biomedica.
Si usa una combinazione della XAS e di altre tecniche sperimentali per studiare tre classi di molecole (i peptidi Aβ, la proteina prionica e la neuromelanina) coinvolte nella patogenesi delle malattie neurodegenerative.
I peptidi Aβ sono la principale componente delle placche amiloidi, che costituiscono una delle lesioni caratteristiche osservate nel cervello dei malati di Alzheimer. È stato osservato che le placche amiloidi contengono elevate concentrazioni di ioni metallici quali Cu e Zn. Si effettuano misure di densità ottica, di spettroscopia infrarossa in trasformata di Fourier e di XAS per determinare la struttura atomica locale dei siti di legame dei metalli. Gli esperimenti mostrano che Cu e Zn hanno ruoli diversi nel processo di aggregazione, ed in particolare che lo Zn è più efficace del Cu nel promuoverla.
La proteina prionica è coinvolta nella patogenesi di una classe di malattie neurodegenerative infettive. In particolare, la conversione di questa proteina dalla sua forma normale alla cosiddetta forma scrapie causa l’enecefalopatia spongiforme trasmissibile. Si è osservato che la regione N-terminale della proteina prionica ha un’elevata affinità per metalli quali Cu e Zn. Gli esperimenti XAS descritti in questa tesi mostrano che il modo di coordinazione del Cu dipende dalla presenza di ioni Zn e che, pur non essendo lo Zn in grado di rimuovere il Cu legato alla proteina, è in grado di modificarne il modo di coordinazione.
La neuromelanina è una molecola che si accumula nei neuroni soggetti a processi neurodegenerativi nelle persone affette dalla malattia di Parkinson. La XAS è qui utilizzata per studiare la coordinazione dello zolfo nella neuromelanina umana, in alcune melanine sintetiche ed in due composti modello contenenti zolfo, la cisteina ed il tricocromo C. Sulla base di fit della neuromelanina umana e delle melanine sintetiche in termini dei composti modello, si riconosce la presenza di modi di coordinazione dello zolfo simili a quelli sia della cisteina, sia del tricocromo, e si quantifica la loro abbondanza relativa.
Infine, la XAS è utilizzata per studiare un problema non connesso alla patogenesi di una malattia neurodegenerativa, ovvero la mancanza di prolidasi. La prolidasi umana è un enzima importante nelle fasi finali del metabolismo delle proteine, e la sua carenza o il suo mancato funzionamento sono alla base di una grave malattia. Nel presente tesi si usa la XAS per determinare il sito di legame di Mn e Zn, mostrando la presenza di un sito di legame dimetallico nella forma attiva della proteina.This thesis describes the application of the X-ray Absorption Spectroscopy (XAS) to the study of biological systems that are particularly interesting for their biomedical role.
Three classes of molecules, namely the Aβ peptides, the prion protein and the neuromelanin, which are related to the pathogenesis of neurodegenerative diseases, are studied by using a combination of XAS and other experimental techniques.
Aβ peptides aggregates are the main component of the amyloid plaques, which are a peculiar lesion found in Alzheimer’s disease brains. The plaques have been shown to contain increased concentration of transition metals like Cu and Zn. Sedimentation assays, Fourier Transform Infrared Spectroscopy and XAS are used to determine the atomic structure around the metal binding site in samples where Aβ peptides are in complex with either Cu or Zn ions. The experiments show that Cu and Zn play different roles, and that Zn is more effective than Cu in promoting peptides aggregation.
The prion protein is related to the pathogenesis of a class of infectious, neurodegenerative diseases. In particular, the conversion of the prion protein from its normal cellular form to the so-called scrapie form is responsible for the transmissible spongiform encephalopathies, and it has been shown that the prion protein is able to bind Cu and Zn ions in its N-terminal octarepeat domain. The XAS experiments reported in this thesis show that the Cu binding mode depends on the presence of Zn ions and, even if Zn is not able to displace Cu, Zn is able to change the way Cu is bound to the prion protein.
Neuromelanin is a complex molecule accumulating in the neurons that undergo a degenerative process in Parkinson’s Disease. XAS is employed to investigate the sulphur binding mode in natural human neuromelanin, in synthetic melanins and in certain structurally known model compounds, namely cysteine and trichochrome C. Based on comparative fits of human and synthetic neuromelanin spectra in terms of those of model compounds, the occurrence of both cysteine- and trichochrome-like sulphur coordination modes is recognized and the relative abundance of these two types of structural arrangement is determined.
Finally, XAS is used to study a biomedical problem not connected to neurodegenerative diseases, that is the prolidase deficiency. Human prolidase is a metalloenzyme that is important in the latest stages of protein catabolism. XAS is employed here to obtain a structural characterization of the Mn and Zn binding sites and shows the existence of heterogeneous dimeric metallic sites in the active form of the protein
Chemokines: key players in innate and adaptive immunity.
No full textHealthy individuals initiate an immediate immune response to microbes by using a set of germline-encoded receptors that recognize common molecular patterns found on the surface of pathogens that are distinct from self-antigens. This innate immune response is the first line of defense against microorganisms in vertebrates, and constitutes the only immune response in plants and invertebrates. The innate immune system includes cellular components, as well as a host of soluble products (antimicrobial peptides, complement fragments, cytokines, and chemokines). The adaptive immune response, which provides long-lasting protection, takes days to develop and requires somatic mutations leading to the development of antigen-specific T cell receptors (cell-mediated immunity) and immunoglobulins (humoral immunity). Members of the chemokine superfamily are crucially involved in both innate and adaptive responses. We review the biological actions of the chemokine superfamily, focusing on several functions that are relevant for both immune responses, such as cell recruitment, microbicidal activity, cell activation, polarization of CD4+ T cells, and effects on structural cells. In particular, we will illustrate the central role that chemokines play in host defense, best demonstrated by the tremendous number of chemokine and chemokine receptor homologs found in microbial genomes, which deflect the immune response of the host
Thesaurus Maintenance, Alignment and Publication as Linked Data: The AGROVOC Use Case
No full textThe AGROVOC multilingual thesaurus maintained by the Food and Agriculture Organization of the United Nations (FAO) is now published as linked data. In order to reach this goal AGROVOC was expressed in Simple Knowledge Organization System (SKOS), and its concepts provided with dereferenceable URIs. AGROVOC is now aligned with ten other multilingual knowledge organization systems related to agriculture, using the SKOS properties exact match and close match. Alignments were automatically produced in Eclipse using a custom-designed tool and then validated by a domain expert. The resulting data is publicly available to both humans and machines using a SPARQL endpoint together with a modified version of Pubby, a lightweight front-end tool for publishing linked data. This paper describes the process that led to the current linked data AGROVOC and discusses current and future applications and directions
Differential regulation of epithelial-derived C-C chemokines by cytokines and budesonide.
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