1,720,962 research outputs found
Identification of new molecular targets for personalized therapy in pediatric patients with inflammatory bowel disease (IBD)
Full text linkLe malattie infiammatorie corniche intestinali (MICI) sono un gruppo di malattie infiammatorie immunomediate che comprendono il morbo di Crohn e la rettocolite ulcerosa. Nella popolazione pediatrica le MICI sono di particolare interesse a causa della aumentata incidenza della malattia e, sebbene siano stati sviluppati diversi approcci terapeutici, è molto difficile individuare il trattamento ottimale. I glucocorticoidi (GC) sono farmaci prescritti per indurre la remissione ma alcuni pazienti risultano resistenti al trattamento o richiedono terapie prolungate e tali pazienti sono soggetti a numerosi reazioni avverse.
Il long non-coding RNA (lncRNA) growth-arrest specific 5 (GAS5) interagisce con il complesso GC-recettore dei glucocorticoidi (GR) inibendo l’attività trascrizionale dei geni responsivi ai GC. La prima parte del mio progetto di tesi si occupa di studiare il ruolo di GAS5 come marker molecolare della resistenza farmacologica ai GC. L’associazione tra il lncRNA e l’efficacia degli steroidi, espressa in termini di inibizione della proliferazione, è stata valutata su due linee cellulari tumorali di colon e ovaio che sono state identificate rispettivamente come modello di resistenza e sensibilità farmacologica ai GC. Inoltre, il ruolo di GAS5 è stato osservato nelle cellule mononucleate del sangue periferico di pazienti pediatrici affetti da MICI sia alla diagnosi che dopo 4 settimane di trattamento con GC; una maggiore espressione di GAS5 è stata osservata nei pazienti con una risposta sfavorevole agli steroidi. Questi risultati preliminari indicano che GAS5 potrebbe essere considerato un nuovo biomarker di resistenza farmacologica ai GC.
I livelli di espressione di GAS5 sono stati valutati anche nelle biopsie di colon di pazienti pediatrici affetti da MICI anche rispetto ai livelli di espressione proteica e genica di due metalloproteasi (MMP) coinvolte nel danno tissutale. La downregolazione di GAS5 osservata nei tessuti infiammati rispetto ai tessuti non infiammati è inversamente correlata all’espressione delle MMP suggerendo che il lncRNA potrebbe controllare l’attività di queste proteine.
Nella seconda parte del mio progetto di tesi abbiamo valutato i livelli di espressione proteica della tristetraprolin (TTP) nelle MICI. La TTP e una proteina zinc finger capace di interagire e inibire le citochine pro-infiammatorie attraverso il legame con gli elementi ricchi di AU sul 3’ UTR degli mRNA target. Abbiamo considerato anche il ruolo della sua fosforilazione, poiché questa modificazione post-traduzionale interferisce con l’attività della TTP che in questo stato è responsabile della stabilizzazione delle citochine d’interesse. L’espressione proteica della TTP è stata valutata nei tessuti di colon e nei macrofagi dei pazienti pediatrici affetti da MICI. L’espressione della TTP risulta upregolata sia nei tessuti di colon che nei macrofagi. I risultati inoltre confermano il coinvolgimento della fosforilazione nell’attività della TTP. Questi risultati preliminari, se confermati con ulteriori esperimenti, potrebbero aprire nuove prospettive nello studio delle IBD e nella formulazione di una nuova terapia farmacologica mirata in grado di modulare la fosforilazione della TTP attraverso l’uso di fosfatasi e favorire così la degradazione delle citochine pro-infiammatorie.Inflammatory bowel disease (IBD) is a chronic immune-mediated condition of the gastrointestinal tract that includes Crohn disease and ulcerative colitis. Pediatric IBDs are of particular interest since their incidence is rising and, even if different pharmacological strategies are used, the optimal treatment is far from being achieved. Glucocorticoid (GCs) are prescribed for inducing remission but there is a high risk of adverse effects especially in subjects that poorly respond to these agents and require long treatments.
The long non-coding RNA (lncRNA) growth arrest-specific 5 (GAS5) interacts with the activated glucocorticoid receptor (GR), inhibiting the transcription of GCs responsive genes. The first part of my thesis project is focused on the study of GAS5 as a molecular marker of GCs resistance. We evaluated the association between the lncRNA and the efficacy of steroids, in terms of inhibition of proliferation, in two immortalized cell lines from colon and ovarian cancers, a GC-resistant and GC-sensitive model, respectively. After GCs treatment in the GC-resistant cells GAS5 upregulation was observed and, in response to the drug, the lncRNA accumulated more in the cytoplasm compared to the nucleus. Furthermore, we evaluated GAS5 levels in the peripheral blood mononuclear cells of pediatric IBD patients at diagnosis and after 4 weeks of GCs administration. Gene expression analysis have shown an upregulation of the lncRNA in patients with unfavourable steroid response. These preliminary results suggest that GAS5 could be considered a novel pharmacogenomic marker useful for the personalization of GC therapy.
GAS5 expression was also measured in IBD patients’ colon biopsies and its levels have been evaluated with respect to the gene and protein expression of two metalloproteinases (MMP-2, MMP-9) involved in tissue damage in IBDs. The GAS5 downregulation observed in inflamed tissues compared with the non-inflamed one is inversely related to MMPs expression suggesting a role of this lncRNA in controlling the activity of these molecules.
In the second part of my thesis project we evaluated the role of the tristetraprolin (TTP) protein in IBDs. TTP is a zinc finger protein able to interact and inhibit pro-inflammatory cytokines through the binding with AU-rich elements on the 3’ untranslated region on mRNA. The role of phosphorylation on TTP activity was also evaluated, since this post-translational modification could impair protein activity and consequently the stabilization of cytokines levels. TTP protein expression was studied in pediatric IBDs patients’ colon tissues and in macrophages differentiated from peripheral blood mononuclear cells. An upregulation of TTP expression in both inflamed colon tissues and in macrophages of IBD patients was observed, and was closely related to the phosphorylation of the protein. These preliminary results, if confirmed with further experiments, could open new perspectives in the study of IBDs and in the investigation of new target therapy based on the modulation of TTP phosphorylation by phosphatases to favour pro-inflammatory cytokines degradation
Glucocorticoid Receptor Interacting Co-regulators: Putative Candidates for Future Drug Targeting Therapy
No full textGlucocorticoids (GCs) are largely used in different inflammatory, autoimmune and proliferative diseases. To date their mechanism of action is not completely clear and more studies are necessary, in particular to explain the great interindividual variability in clinical response. In this panorama the glucocorticoid receptor (GR) has an important role: in fact it regulates the pharmacological response thanks to the capability to interact with different molecules (DNA, RNA, ncRNA and proteins) that are known to influence its activity. In this review our aim is to highlight the knowledge about the role of protein-protein, RNA-protein interactions and epigenetic modifications on the GR and the consequent response to GCs. The characteristics of these interactions with the GR and their effects on the pharmacological activity of GCs will be examined. This information could contribute to the prediction of individual sensitivity to steroids through the identification of new markers of GC resistance. In addition this knowledge may be used in developing new strategies for targeted therapy
Pharmacotranscriptomic Biomarkers in Glucocorticoid Treatment of Pediatric Inflammatory Bowel Disease
No full textPharmacotranscriptomics aims to reach more accurate drug dosing based on interindividual transcriptome variations. Here, we provide an overview of RNA biomarkers that could predict the response to glucocorticoids (GCs), considered the standard for treatment of inflammatory bowel diseases (IBD), both in adult and pediatric patients. Although new biological agents are very effective in IBD treatment, GCs are still widely used for induction of remission in patients with moderate to severe disease. It is important to identify patients that are poor responders to GCs therapy, because suboptimal response is frequent and associated with various side effects. A number of genetic variants related to GC mechanism of action has been studied. However, the majority of reported associations are not consistent. In this regard, pharmacogenomic research is now exploring the world of RNAs. An appropriate regulation of the transcriptome, which mainly comprises mRNAs and non-coding RNAs that control gene expression, has a strong impact in the modulation of GC activity
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
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
Carbamazepine-induced thrombocytopenic purpura in a child: Insights from a genomic analysis
No full textTo the Editor,
Carbamazepine is an effective anticonvulsant and has a relatively low incidence of adverse effects, although it occasionally causes hema- tologic disorders. We herein describe a patient with carbamazepine- induced thrombocytopenic purpura that was investigated by pharma- cological, immunological and genomic assays
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