β-Catenin is necessary to keep cells of ureteric bud/Wolffian duct epithelium in a precursor state

AbstractDifferentiation is the process by which tissues/organs take on their final, physiologically functional form. This process is mediated in part by the silencing of embryonic genes and the activation of terminal, differentiation gene products. Mammalian kidney development is initiated when the Wolffian duct branches and invades the overlying metanephric mesenchyme. The newly formed epithelial bud, known as the ureteric bud, will continue to branch ultimately differentiating into the collecting duct system and ureter. Here, we show that Hoxb7-Cre mediated removal of β-catenin from the mouse Wolffian duct epithelium leads to the premature expression of gene products normally associated with the differentiated kidney collecting duct system including the water channel protein, Aquaporin-3 and the tight junction protein isoform, ZO-1α+. Mutant cells fail to maintain expression of some genes associated with embryonic development, including several mediators of branching morphogenesis, which subsequently leads to kidney aplasia or hypoplasia. Reciprocally, expression of a stabilized form of β-catenin appears to block differentiation of the collecting ducts. All of these defects occur in the absence of any effects on the adherens junctions. These data indicate a role for β-catenin in maintaining cells of the Wolffian ducts and the duct derived ureteric bud/collecting duct system in an undifferentiated or precursor state

Biocompatibilità e durata in vivo di cinque nuovi polimeri sintetici testati su coniglio

I materiali alloplastici vengono frequentemente utilizzati negli interventi di chirurgia plastica sul volto, quali la rinoplastica e la chirurgia ricostruttiva del naso. Ad oggi non è stato ancora individuato un materiale alloplastico con caratteristiche ottimali. Il presente studio sperimentale si propone di valutare la risposta tissutale e la resistenza nel tempo di cinque nuovi polimeri proposti come materiali alloplastici. Il presente studio è stato condotto presso un ospedale universitario di terzo livello. Sono state ricavate sei tasche sottocutanee sul dorso di 10 conigli che sono state usate per l’impianto di ciascuno dei polimeri testati più una tasca di controllo. Ciascuna delle tasche è stata escissa congiuntamente al tessuto circostante dopo tre mesi, ed è stata sottoposta ad un esame istopatologico. È stata quindi condotta una valutazione semi quantitativa con focus su neo angiogenesi, infiammazione, fibrosi, formazione di ascessi, presenza di cellule giganti multinucleate contenenti corpi estranei e stato dei polimeri testati. E’ stata inoltre effettuata una valutazione statistica, che per quanto riguarda la comparazione diretta fra la tasca di controllo e i polimeri II, III e IV non ha mostrato differenze significative in merito alla neo vascolarizzazione, all’infiammazione, alla fibrosi, alla presenza di ascessi ed alla presenza di cellule giganti multinucleate. Il polimero I ha invece mostrato un grado di fibrosi inferiore rispetto alla tasca di controllo (p = .027) and V (p = .018), benché le altre variabili prese in considerazione fossero sostanzialmente uguali. L’integrità nel tempo dei polimeri III (9 intatti, uno frammentato) e IV (8 intatti, 2 assenti) è stata migliore di quella ottenuta con gli altri polimeri testati. Questo gruppo di nuovi polimeri può essere considerato interessante per future applicazioni cliniche. Tutti i polimeri hanno mostrato risultati accettabili in termini di risposta dei tessuti, tuttavia i fenomeni di integrazione fibrovascolare sono stati maggiori nel caso dei polimeri II, III e IV. Inoltre la durata nel tempo dei polimeri III e IV è stata la migliore in assoluto

Value of p53 protein in biological behavior of basal cell carcinoma and in normal epithelia adjacent to carcinomas

Mutations in p53 gene are the most frequent gene alterations in human cancer. In this study, we have used the monoclonal antibody (DO7) to evaluate the role of the p53 gene mutation in the progression of basal cell carcinomas towards invasion. We tested the positivity for p53 protein in tumor cells in six cases of basosquamous cell carcinoma (BSCC), in twelve cases of infiltrative basal cell carcinoma (IBCC) and twenty-four cases of non-infiltrative basal cell carcinoma (NIBCC) in order to evaluate its potential prognostic significance. We also tested the expression of p53 protein in normal epithelia adjacent to carcinomas in order to determine its role in tumor progression. p53 protein staining with some peripheral accentuation was identified in 42,9% of all groups. No correlation was found between the immunreactivity of p53 protein and recurrence, pattern of tumor, diameter of the tumors and sex. However, there were statistically significant differences in positivity of p53 protein in normal epithelia adjacent to carcinomas and age of patients (t value: 2,21; p: 0,034). Results of the study suggest that the increase in p53 mutation frequency of morphologically normal epidermis was related to age and was independent of the degree of differentiation of BCC. © 2000 W B. Saunders and Company Ltd on behalf of the Ar£nyi Lajos Foundation

The genetic heterogeneity and mutational burden of engineered melanomas in zebrafish models.

BACKGROUND: Melanoma is the most deadly form of skin cancer. Expression of oncogenic BRAF or NRAS, which are frequently mutated in human melanomas, promote the formation of nevi but are not sufficient for tumorigenesis. Even with germline mutated p53, these engineered melanomas present with variable onset and pathology, implicating additional somatic mutations in a multi-hit tumorigenic process. RESULTS: To decipher the genetics of these melanomas, we sequence the protein coding exons of 53 primary melanomas generated from several BRAF(V600E) or NRAS(Q61K) driven transgenic zebrafish lines. We find that engineered zebrafish melanomas show an overall low mutation burden, which has a strong, inverse association with the number of initiating germline drivers. Although tumors reveal distinct mutation spectrums, they show mostly C > T transitions without UV light exposure, and enrichment of mutations in melanogenesis, p53 and MAPK signaling. Importantly, a recurrent amplification occurring with pre-configured drivers BRAF(V600E) and p53-/- suggests a novel path of BRAF cooperativity through the protein kinase A pathway. CONCLUSION: This is the first analysis of a melanoma mutational landscape in the absence of UV light, where tumors manifest with remarkably low mutation burden and high heterogeneity. Genotype specific amplification of protein kinase A in cooperation with BRAF and p53 mutation suggests the involvement of melanogenesis in these tumors. This work is important for defining the spectrum of events in BRAF or NRAS driven melanoma in the absence of UV light, and for informed exploitation of models such as transgenic zebrafish to better understand mechanisms leading to human melanoma formation

Do salivary bypass tubes lower the incidence of pharyngocutaneous fistula following total laryngectomy? A retrospective analysis of predictive factors using multivariate analysis

Salivary bypass tubes (SBT) are increasingly used to prevent pharyngocutaneous fistula (PCF) following laryngectomy and pharyngolaryngectomy. There is minimal evidence as to their efficacy and literature is limited. The aim of the study was to determine if SBT prevent PCF. The study was a multicentre retrospective case control series (level of evidence 3b). Patients who underwent laryngectomy or pharyngolaryngectomy for cancer or following cancer treatment between 2011 and 2014 were included in the study. The primary outcome was development of a PCF. Other variables recorded were age, sex, prior radiotherapy or chemoradiotherapy, prior tracheostomy, type of procedure, concurrent neck dissection, use of flap reconstruction, use of prophylactic antibiotics, the suture material used for the anastomosis, tumour T stage, histological margins, day one post-operative haemoglobin and whether a salivary bypass tube was used. Univariate and multivariate analysis were performed. A total of 199 patients were included and 24 received salivary bypass tubes. Fistula rates were 8.3% in the SBT group (2/24) and 24.6% in the control group (43/175). This was not statistically significant on univariate (p value 0.115) or multivariate analysis (p value 0.076). In addition, no other co-variables were found to be significant. No group has proven a benefit of salivary bypass tubes on multivariate analysis. The study was limited by a small case group, variations in tube duration and subjects given a tube may have been identified as high risk of fistula. Further prospective studies are warranted prior to recommendation of salivary bypass tubes following laryngectomy

Radiological progression of cerebral metastases after radiosurgery: assessment of perfusion MRI for differentiating between necrosis and recurrence

To assess the capability of perfusion MRI to differentiate between necrosis and tumor recurrence in patients showing radiological progression of cerebral metastases treated with stereotactic radiosurgery (SRS). From 2004 to 2006 dynamic susceptibility-weighted contrast-enhanced perfusion MRI scans were performed on patients with cerebral metastasis showing radiological progression after SRS during follow-up. Several perfusion MRI characteristics were examined: a subjective visual score of the relative cerebral blood volume (rCBV) map and quantitative rCBV measurements of the contrast-enhanced areas of maximal perfusion. For a total of 34 lesions in 31 patients a perfusion MRI was performed. Diagnoses were based on histology, definite radiological decrease or a combination of radiological and clinical follow-up. The diagnosis of tumor recurrence was obtained in 20 of 34 lesions, and tumor necrosis in 14 of 34. Regression analyses for all measures proved statistically significant (χ2 = 11.6–21.6, P < 0.001–0.0001). Visual inspection of the rCBV map yielded a sensitivity and specificity of 70.0 respectively 92.9%. The optimal cutoff point for maximal tumor rCBV relative to white matter was 2.00 (improving the sensibility to 85.0%) and 1.85 relative to grey matter (GM), improving the specificity to 100%, with a corresponding sensitivity of 70.0%. Perfusion MRI seems to be a useful tool in the differentiation of necrosis and tumor recurrence after SRS. For the patients displaying a rCBV-GM greater than 1.85, the diagnosis of necrosis was excluded. Salvage treatment can be initiated for these patients in an attempt to prolong survival

Prediction of acute myeloid leukaemia risk in healthy individuals

The incidence of acute myeloid leukaemia (AML) increases with age and mortality exceeds 90% when diagnosed after age 65. Most cases arise without any detectable early symptoms and patients usually present with the acute complications of bone marrow failure(1). The onset of such de novo AML cases is typically preceded by the accumulation of somatic mutations in preleukaemic haematopoietic stem and progenitor cells (HSPCs) that undergo clonal expansion(2,3). However, recurrent AML mutations also accumulate in HSPCs during ageing of healthy individuals who do not develop AML, a phenomenon referred to as age-related clonal haematopoiesis (ARCH)(4-8). Here we use deep sequencing to analyse genes that are recurrently mutated in AML to distinguish between individuals who have a high risk of developing AML and those with benign ARCH. We analysed peripheral blood cells from 95 individuals that were obtained on average 6.3 years before AML diagnosis (pre-AML group), together with 414 unselected age- and gender-matched individuals (control group). Pre-AML cases were distinct from controls and had more mutations per sample, higher variant allele frequencies, indicating greater clonal expansion, and showed enrichment of mutations in specific genes. Genetic parameters were used to derive a model that accurately predicted AML-free survival; this model was validated in an independent cohort of 29 pre-AML cases and 262 controls. Because AML is rare, we also developed an AML predictive model using a large electronic health record database that identified individuals at greater risk. Collectively our findings provide proof-of-concept that it is possible to discriminate ARCH from pre-AML many years before malignant transformation. This could in future enable earlier detection and monitoring, and may help to inform intervention