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GENETICA MOLECOLARE, EPIDEMIOLOGIA, PATOGENESI DEL RENE MIDOLLARE A SPUGNA
Get PDFMedullary Sponge Kidney (MSK) was recognized for the first time in Padua, in 1939 by Lenarduzzi utilizing a new urography technique and subsequently described in 1949 by Cacchi and Ricci respectively urologist and pathologist at the University of Padua. Since its association with other congenital renal and extrarenal malformations, MSK may be considered among the congenital renal malformations also due to the presence of precalyceal ectasia of collecting ducts . The renal function and life span are normal in MSK patients, neverthless MSK is often complicated by the development of nephrocalcinosis and nephrolithiasis. The pathogenesis of MSK has not been totally elucidated but many authors agree that it is a congenital disease with delayed expression. A genetic cause for MSK could be suggested by the description of some familial cases, by its link to the group of congenital malformations and by its association with other inherited diseases. Recently, the discovery of the genes responsible for this disease has attracted the attention of our group work and in particular of my PhD work. The working hypothesis is that MSK is the consequence of a disturbance in the ureteric bud- metanephric blastema interface, which might be due either to disease- causing mutation/ specific polymorphism of RET, GDNF and other genes involved in the inter-facing, or to particular RET/GDNF genotype interaction. The results of direct sequencing and RFLP testing of GDNF on a population of 112 , unrelated of Venetian origin MSK patients selected on the basis of strict urographic criteria led to the identification of a rare variant of GDNF promoter region (27+18G>A) significantly associated with MSK (p=0.02). In addition, the possibility to extend GDNF screening to the family members of MSK patients carrying rare variants allowed us to discover that the variants were inherited and that they were associated with the MS K phenotype. In the second part of the study it has been placed attention to the familial cases of MSK. Sampling 50 cases from the cohort of 112 sporadic MSK cases, and analyzing family members of the 1° and 2° generations by ultrasonography and /or UroTAC, we found that in 27 families MSK was inherited as an autosomal dominant trait, with variable expressivity and incomplete penetrance. In 19 families the screening of GDNF gene was conducted and, in addition, the screening of Six1, Spry1 and PAX2 genes that are involved in nephrogenesis with an important role in the mechanisms of GDNF regulation was performed. Sequencing of exon and intron boundaries of GDNF gene on the 19 families did not reveal any nucleotide substitutions or rare variants. Similarly, no causative mutation was found for Six1, Spry1 and Pax2. For Spry1 and Pax2 polymorphisms have been found but without any significance in the allele frequency as compared to control population. Another objective of the study was to understand the functional significance od GDNF rare variants in the context of MSK phenotype. The removal of a renal cell carcinoma in a MSK patient with the GDNF intronic (-27+18 G / C )rare variant gave us the opportunity to study MSK papillary cells in culture. We observed an exceptional phenomenon, the appearance of an osteogenic-like phenotype with deposition of calcium phosphate. We wonder if the down-regulation of GDNF expression that was lower in MSK cells in respect to control cells were the culprit of the observed phenomenon. To investigate if GDNF down-regulation most likely due to the mutation in the promoter region, may have had a role in the process of spontaneous calcification, we have stably silenced GDNF gene in human renal epithelial cells (HK2), through the technique of RNA interference. Preliminary data from these experiments showed in the silenced HK2 cells cultured under osteogenic conditions the presence of aggregates that Won Kossa staining and SEM analysis confirmed to be of Ca2PO4. The presence of calcium phosphate deposits were not observed in control negative as well as in silenced clones cultured in normal conditions, while in control negative cells under osteogenic stimulation few deposits were seen, however in lower number in respect to silenced cells. Although preliminary, our results suggest that GDNF down regulation in HK2 cells may favor Ca2PO4 deposition throught a mechanism not yet identified. Our hypothesis is that apoptosis might be the key.IL Rene con Midollare a Spugna (MSK) riconosciuto per la prima volta a Padova, da Lenarduzzi nel 1939 grazie all’impiego dell’allora nuova tecnica dell’urografia e successivamente descritto nel 1949 da Cacchi e Ricci, rispettivamente urologo e patologo dell’Università patavina può essere annoverato tra le nefropatie congenite malformative per la presenza di ectasie precaliceali dei dotti collettori e per la sua frequente associazione con altre malformazioni congenite renali ed extrarenali. La funzione renale e la durata della vita nei pazienti MSK è normale; spesso si complica con lo sviluppo di nefrocalcinosi e nefrolitiasi. La patogenesi di MSK non è stata completamente chiarita ma la maggior parte degli autori concorda che si tratta di una patologia congenita con espressione ritardata. Che la causa di MSK potesse essere di natura genetica era suggerito dalla descrizione di alcuni casi familiari, dall’appartenenza di MSK al gruppo delle patologie malformative e dalla sua associazione con altre malattie ereditarie. La scoperta del gene/i responsabili della patologia è stato negli ultimi anni obiettivo del nostro gruppo di lavoro ed in particolare del mio lavoro di dottorato. L’ipotesi che ha dato inizio allo studio è che MSK sia la conseguenza di un disturbo durante lo sviluppo renale dell’interfaccia “gemma ureterale- mesenchima metanefrico” a causa di mutazioni/polimorfismi di RET, GDNF, o di altri geni coinvolti nell’embriogenesi renale, o in particolare a causa dell’interazione GDNF/RET. I risultati del sequenziamento diretto e test RFLP di GDNF su una casistica veneta di 112 pazienti, ben selezionata sulla base di stretti criteri urografici hanno permesso di identificare 1 variante rara della regione del promotore di GDNF (-27+18G>A) significativamente associata a MSK (p=0.02). Inoltre, la possibilità di estendere lo screening di GDNF su alcuni familiari di pazienti MSK ci ha permesso di scoprire che le varianti erano ereditate e che nelle famiglie erano associate al fenotipo MSK. Nella seconda parte del lavoro di dottorato è stata posta l’attenzione sui casi familiari di MSK.
In collaborazione con la Clinica Nefrologica di Verona sono stati indagati 50 gruppi famigliari scelti random dalla coorte di 112 pazienti con MSK . Dall’’analisi mediante ecografia e/o Uro-TC estesa ai consanguinei della stessa generazione, e di 1, se possibile, 2 generazioni precedenti e/o successive è emerso che in 27 famiglie MSK segregava come carattere autosomico dominante, con espressività variabile e ridotta penetranza. Sui probandi di queste famiglie è stato fatto lo screening per il gene GDNF. Inoltre, in collaborazione con il laboratorio di Nefrologia Pediatrica dell’Università di Padova è stato fatto, lo screening di Six1, Spry1 e Pax2 che sono geni coinvolti nel processo di nefrogenesi renale e con un importante ruolo nei meccanismi di regolazione di GDNF, per un totale di 19 casi famigliari. Lo screening di GDNF mediante sequenziamento diretto delle regioni esoniche e delle giunzioni introne-esone non ha evidenziato nessuna variante rare né altre sostituzioni nucleotidiche. Allo stesso modo nessuna mutazione causativa è stata evidenziata per Six1, Spry1 e Pax2. Per Spry1 e Pax2 solo polimorfismi noti ma senza alcuna significatività statistica nelle frequenze alleliche confrontata con quella di popolazioni di controllo riportate in letteratura. Un altro obiettivo del mio lavoro di dottorato è stato quello di aver cercato di capire come varianti rare di GDNF possano essere associate al fenotipo MSK, in un sottogruppo di pazienti con nefrolitiasi, nefrocalcinosi ed MSK bilaterale. L’asportazione di un carcinoma renale in una paziente con MSK e mutazione di GDNF (-27+18G/C) ha dato l’opportunità di studiare per la mutazione di GDNF il suo significato funzionale e di verificare che cellule papillari renale prelevate da polo indenne al carcinoma renale e con bassi profili di espressione per GDNF, differenziavano spontaneamente verso un lineaggio osteogenico con la sintesi di proteine tipiche della matrice osteoide. Per cercare di approfondire se la down regolazione di GDNF, molto probabilmente dovuta alla mutazione che cade nella regione del promotore, possa avere avuto un coinvolgimento nel fenomeno di calcificazione osservato si è cercato di ottenere su cellule epiteliali renali (HK2), attraverso la tecnica di RNA interference, un silenziamento stabile di GDNF. I dati preliminari di questi ultimi esperimenti hanno mostrato che nelle cellule HK2 silenziate per GDNF vi era la presenza di depositi di Ca2PO4, confermati sia dalla colorazione von Kossa sia dall’analisi SEM. la presenza dei depositi di calcio fosfato non sono state osservate né nel controllo negativo né nei cloni silenziati in normali condizioni di coltura, mentre nel controllo negativo in condizione osteogenica i depositi erano presenti, seppur in minore quantità rispetto al clone silenziato. Sebbene preliminari, i nostri suggeriscono che la down regolazione di GDNF potrebbe favorire la deposizione di Ca2PO4 attraverso un meccanismo non ancora identificato. La nostra ipotesi è che l’apoptosi potrebbe essere la chiave
Rare genomic variants and susceptibility to multifactorial diseases. The example of medullary sponge kidney
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
The Regenerative Potential of the Kidney: What Can We Learn from Developmental Biology?
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Cell turnover in the healthy adult kidney is very slow but the kidney has a strong capacity for regeneration after acute injury. Although many molecular aspects of this process have been clarified, the source of the newly-formed renal epithelial cells is still being debated. Several studies have shown, moreover, that the repair of injured renal epithelium starts from mature tubular cells, which enter into an activated proliferative state characterized by the reappearance of mesenchymal markers detectable during nephrogenesis, thus pointing to a marked plasticity of renal epithelial cells. The regenerative potential of mature epithelial cells might stem from their almost unique morphogenetic process. Unlike other tubular organs, all epithelial and mesenchymal cells in the kidney derive from the same germ layer, the mesoderm. In a fascinating view of vertebrate embryogenesis, the mesoderm might be seen as a cell layer capable of oscillating between epithelial and mesenchymal states, thus acquiring a remarkable plasticity that lends it an extended potential for innovation and a better control of three-dimensional body organization. The renal papilla contains a population of cells with the characteristic of adult stem cells. Mesenchymal stromal stem cells (MSC) have been found to reside in the connective tissue of most organs, including the kidney. Recent studies indicate that the MSC compartment extends throughout the body postnatally as a result of its perivascular location. Developmental biology suggests that this might be particularly true of the kidney and that the papilla might represent the perivascular renal stem cell niche. The perivascular niche hypothesis fits well with the evolving concept of the stem cell niche as an entity of action. It is its dynamic capability that makes the niche concept so important and essential to the feasibility of regenerative medicine
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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