1,720,960 research outputs found
Environmental adaptation of Legionella pneumophila under chlorine treatment in a water hospital network
No full textRisposta adattativa di ceppi di Legionella pneumophila esposti a clorazione continua in una rete idrica ospedaliera
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
“Impiego di un adiuvante Th1 di origine batterica per la modulazione della risposta Th2 in vivo: studio in un modello di trichinellosi sperimentale”
No full textDuring Trichinella spiralis infection host defense is based on eosinophilia and increased IgE levels, as observed in Th2 mediated diseases like asthma and allergic rhinitis. Nowadays allergic diseases are treated with an alternative approach to the usual immunesuppressive method, using the mutual antagonism between Th1 and Th2 cytokines. For this reason the research has investigated new Th1 adjuvant molecules able to contrast the exacerbated Th2 responses to allergens. In particular among a large panel of pro-Th1 adjuvants, the protein of bacterial origin Helicobacter pylori neutrophil activating protein (HP-NAP) can induce immunity cells to activate towards a Th1 phenotype, also acting in vitro on Th2 polarized cells.
The aim of the present PhD thesis was to verify the immunological efficacy of HP-NAP in the experimental mouse model of T. spiralis infection, characterized by a Th2 immune response, which represents an alternative to the classical approach of ovalbumin-induced asthma. This experimental study offers not only the possibility to evaluate the immunological effects of the bacterial adjuvant, but also to assess parasitological issue in the immunomodulated host-parasite relationship.
After a preliminary study a dosage of 10 μg of HP-NAP was chosen to be administered intraperitoneally at 10th and 28th day after experimental infection in correspondence with eosinophilia peak and plasma IgE level plateau in our mouse model of T. spiralis infection, respectively. HP-NAP used was cloned and espressed in the Gram positive Bacillus subtilis to avoid endotoxin contamination. Peripheral blood collection from different experimental groups (infected animals treated with HP-NAP or with PBS) allowed us to study the immune response along the infection using leukocyte count, total and parasite specific IgE level and cytokine profile determination. In addition, splenocytes from treated and control animals were used in an ex vivo system to confirm HP-NAP immunomodulation and identify cellular target and the respective receptor involved in HP-NAP signaling pathway on immunity cells. Further, in vivo experiments were performed using our bacterial adjuvant in addition to the antibody blocking the toll-like receptor 2 (TLR2) which is responsible for HP-NAP signal transmission.
For the evaluation of parasitological aspects, animals were examined by histological, histochemical and immunohistochemistry analysis at muscle level and their carcasses were digested in a chloride pepsin solution for parasitological burden assessment.
Results obtained from our experimental work showed HP-NAP ability to immunomodulate the Th2 response, reducing significantly eosinophils peak and total and parasite IgE levels during the helminthic infection. HP-NAP action resulted strongly active in increasing IFN-γ and IL-12 levels and diminishing IL-4 and IL-5 levels both in animals treated with HP-NAP and in ex-vivo system derived from treated infected mouse spleens compared to cells from infected animal controls. Besides, the ex-vivo experiments confirmed HP-NAP action on innate immunity cells through HP-NAP/TLR2 binding, able to stimulate a cytokine profile expression different from that of another TLR2 agonist such as PAM3. All these data show that HP-NAP, acting through the TLR2, is capable also in vivo to shift the immune response to a Th1 phenotype.
After having studied the effects of HP-NAP in immunological response, we aimed to understand the host-parasite relation focusing on Trichinella muscle phase, during which the parasite enters the striated skeletal muscle cell inducing the nurse cell formation, devoted to nourishing and to protection of the helminth.
Histological analysis evidenced by means of an appropriate software an increased inflammation infiltrate surrounding nurse cell-parasite complex in HP-NAP treated animals, in addition to elevated active matrix metalloproteinase 9 (MMP-9) plasma levels, considered a leukocyte transendothelial migration marker. Histochemical staining revealed a reduction in eosinophil number in muscular pericapsular inflammation in HP-NAP treated animals, confirming the decrease of these polymorphonucleate cells at blood level. This suggests that the decrease in the blood induced by HP-NAP is not due to an increased extravasation of eosinophils but rather to the reduced IL-5 plasma levels observed in HP-NAP treated animals.
Immunohistochemistry with an anti-arginase 1 antibody, an enzyme which is considered a marker of alternative macrophage activation, showed a decreased staining of this enzyme in muscle inflammatory infiltrate of treated infected animals. Surprisingly, parasite burden of HP-NAP treated animals is thrice times that of control animal. It is important underline that the first HP-NAP administration when intestinal parasite phase is not yet ended in the mouse strains used (BALB/c) shifted host immunity to a Th1 response, which might have delayed worm expulsion, increasing the number of migrant larvae produced. Besides inverse correlation between parasite burden and Th2 parameters (eosinophils, total and specific IgE) suggests the importance of this type of host immune response against parasite infection.
Our experimental design offers a dualistic point of view. In experimental helminthic infection the molecule of bacterial origin confirms its immunological potential, shifting host immune response to Trichinella infection. Immunomodulation of parasite infection provides new information on host- parasite relationship: in our model the Th2 immune response acquires an host protective value in favor of host defense versus massive Trichinella infection in muscle
Il rapporto ospite-parassita nella trichinellosi sperimentale: ruolo della GSTO
No full textGli enzimi antiossidanti partecipano ai meccanismi evasivi adottati dal parassita, nel nostro caso Trichinella spp., per persistere a lungo nell’ospite: la coesistenza ospite-parassita si esplica con successo quando il parassita riesce ad interferire con la risposta immune dell’ospite, modulandone l’attività delle cellule effettrici e difendendosi dalle specie reattive dell’O2, prodotte da queste ultime.
Un modello di infezione elmintica molto studiato è quello causato da Trichinella, genere che racchiude 8 specie, di cui alcune incapsulate ed altre no. Questo parassita é causa di zoonosi distribuite in diverse regioni del mondo. Dopo l’iniziale fase intestinale, Trichinella spp. si localizza nei muscoli striati dell’ospite inducendo forti cambiamenti morfologici e strutturali nella cellula invasa, che acquisisce un nuovo fenotipo detto nurse cell (NC). All’infezione si accompagna una forte risposta infiammatoria ed immunitaria dell’ospite, caratterizzata tra l’altro da un’elevata eosinofilia e da un innalzamento del livello di IgE sieriche.
Scopo di questa tesi è stato quello di valutare la risposta antiossidante del parassita nei muscoli attraverso lo studio dell’enzima glutatione transferasi Omega (GSTO). Tale enzima è privo di attività glutatione-transferasica, ma è dotato di numerose altre funzioni di grande importanza nella risposta allo stress ossidativo quali l’attività tioltransferasica e deidroascorbato reduttasica.
Con l’utilizzo di un anticorpo policlonale anti-GSTO di ratto sono stati condotti esperimenti di immunoblot e di immunoistochimica su larve isolate, sul tessuto muscolare infetto e di controllo. Si è inoltre valutata l’espressione del gene specifico per GSTO con la tecnica dell’ibridazione in situ, impiegando una sonda complementare al relativo mRNA di topo su sezioni di tessuto infetto a diverse epoche d’infezione.
I risultati ottenuti hanno dimostrato che:
- larve L1 di Trichinella spp. non sono riconosciute dall’anticorpo policlonale anti-GSTO;
- negli studi di immunoistochimica, la nurse cell in animali da esperimento infettati sia da Trichinella spiralis sia da Trichinella britovi (entrambe specie incapsulate) è risultata fortemente colorata dallo stesso anticorpo, a differenza del tessuto muscolare circostante; ciò è stato confermato con immunoblot su citosol di tessuto muscolare;
- tale risultato non si è ottenuto in animali infettati da Trichinella pseudospiralis che è una tipica specie non incapsulata;
- in animali trattati con antielmintico non è stata osservata l’up-regulation della proteina enzimatica suggerendo un possibile ruolo attivo del parassita in questo processo;
- mediante ibridazione in situ è stato osservato che, nei giorni successivi all’invasione della larva di Trichinella britovi nei muscoli, l’espressione dell’enzima GSTO nella nurse cell aumenta gradualmente;
- mediante confronto tra una GST di Trichinella spp. e GST di mammifero è stato osservato che non esiste alcuna omologia tra le sequenze nucleotidiche relative ai due enzimi.
Questi risultati potrebbero aprire nuove vie per l’identificazione di target utili per il controllo di questa importante parassitosi
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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