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Prague, Czech Republic

Petersson F.,National University of Singapore | Petersson F.,Charles University | Michal M.,Charles University | Vanecek T.,Charles University | And 4 more authors.
Annals of Diagnostic Pathology | Year: 2011

A 34-year-old pregnant woman with bilateral kidney tumors 9.5 and 2.5 cm in maximum diameter is presented. The larger tumor was clear renal cell carcinoma. The smaller contralateral tumor was focally HMB45 positive and had unusual histomorphology, including features resembling clear renal cell carcinoma with features of both t(6;11)- and t(X;17)/ASPL-TFE3 carcinomas. This tumor displayed a complex karyotype. A novel germ line mutation in the VHL gene (c.439A>G/p.I147V) was also identified in this patient. © 2011 Elsevier Inc. Source


Petersson F.,Charles University | Petersson F.,National University of Singapore | Vanecek T.,Charles University | Michal M.,Charles University | And 13 more authors.
Human Pathology | Year: 2012

To date, only a few cases of "rosette forming t(6;11), HMB45-positive renal carcinoma" have been published. In this article, we contribute further data on 4 cases of this rare entity. Patients were 3 women and 1 man with an age range of 20 to 54 years (median, 23 years). Follow-up (range, 3-5 years; median, 4 years) did not reveal any metastatic events or recurrences. All tumors were well circumscribed and mostly encapsulated with homogeneous gray to tan cut surfaces. No necrosis was seen. All tumors displayed a solid or solid/alveolar architecture and contained occasionally long and branching tubular structures composed of discohesive neoplastic cells and pseudorosettes. The presence of pseudorosettes was a constant finding, but the number of pseudorosettes varied significantly among cases. All cases displayed focal immunoreactivity for the melanocytic marker HMB45, cathepsin K, and vimentin. Melan A, tyrosinase, cytokeratins, CD10, and microphthalmia transcription factor were each positive in 3 of 4 cases. On ultrastructural examination, numerous electron-dense secretory cytoplasmic granules with some resemblance to melanosomes were identified. The pseudorosettes were composed of reduplicated basement membrane material surrounded by small lymphocyte-like neoplastic cells. Using reverse transcription polymerase chain reaction, 2 tumors were positive for the Alpha-TFEB fusion transcript. The presence of the translocation t(6;11)(Alpha-TFEB) was confirmed in 2 analyzed cases. No von Hippel-Lindau tumor suppressor gene mutation, promotor methylation or loss of heterozygosity of 3p was found. Losses of part of chromosome 1 and chromosome 22 were found in one case. © 2012 Elsevier Inc. All rights reserved. Source


Li F.,Johns Hopkins University | Li F.,Kaiser Permanente | Shen Y.,Harvard University | Sharkey F.H.,Microarray Facility | And 21 more authors.
European Journal of Medical Genetics | Year: 2010

The use of comparative genomic hybridization (CGH) and single nucleotide polymorphism (SNP) arrays has dramatically altered the approach to identification of genetic alterations that can explain intellectual disability and /or congenital anomalies. However, the discovery of numerous copy number changes with benign or unknown clinical significance has made interpretation problematic. Submicroscopic duplication of Xp22.31 has been reported as either a possible cause of intellectual disability and/or developmental delay or a benign variant. Here we report 29 individuals with the microduplication found as part of microarray analysis of 7793 samples submitted to an international group of 13 clinical laboratories. The referral reasons varied and included developmental delay, intellectual disability, autism, dysmorphic features and/or multiple congenital anomalies. The size of the Xp22.31 duplication varied between 149 kb and 1.74 Mb and included the steroid sulfatase (STS) gene with the male to female ratio of 0.7. Duplication within this segment is seen at a frequency of 0.15% in a healthy control population, whereas a frequency of 0.37% was observed in our cohort of individuals with abnormal phenotypes. We present a detailed comparison of the breakpoints, inheritance, X-inactivation and clinical phenotype in our cohort and a review of the literature for a total of 41 patients. To date, this report is the largest compilation of clinical and array data regarding the microduplication of Xp22.31 and will serve to broaden the knowledge of regions involving copy number variation (CNV). © 2010 Elsevier Masson SAS. All rights reserved. Source


Martens G.A.,Vrije Universiteit Brussel | Martens G.A.,Universitair Ziekenhuis Brussel | Jiang L.,Vrije Universiteit Brussel | Hellemans K.H.,Vrije Universiteit Brussel | And 8 more authors.
PLoS ONE | Year: 2011

Background and Methodology: The aim of this study was to establish a gene expression blueprint of pancreatic beta cells conserved from rodents to humans and to evaluate its applicability to assess shifts in the beta cell differentiated state. Genome-wide mRNA expression profiles of isolated beta cells were compared to those of a large panel of other tissue and cell types, and transcripts with beta cell-abundant and -selective expression were identified. Iteration of this analysis in mouse, rat and human tissues generated a panel of conserved beta cell biomarkers. This panel was then used to compare isolated versus laser capture microdissected beta cells, monitor adaptations of the beta cell phenotype to fasting, and retrieve possible conserved transcriptional regulators. Principal Findings: A panel of 332 conserved beta cell biomarker genes was found to discriminate both isolated and laser capture microdissected beta cells from all other examined cell types. Of all conserved beta cell-markers, 15% were strongly beta cell-selective and functionally associated to hormone processing, 15% were shared with neuronal cells and associated to regulated synaptic vesicle transport and 30% with immune plus gut mucosal tissues reflecting active protein synthesis. Fasting specifically down-regulated the latter cluster, but preserved the neuronal and strongly beta cell-selective traits, indicating preserved differentiated state. Analysis of consensus binding site enrichment indicated major roles of CREB/ATF and various nutrient- or redox-regulated transcription factors in maintenance of differentiated beta cell phenotype. Conclusions: Conserved beta cell marker genes contain major gene clusters defined by their beta cell selectivity or by their additional abundance in either neural cells or in immune plus gut mucosal cells. This panel can be used as a template to identify changes in the differentiated state of beta cells. © 2011 Martens et al. Source


Swales N.,Vrije Universiteit Brussel | Martens G.A.,Vrije Universiteit Brussel | Bonne S.,Vrije Universiteit Brussel | Heremans Y.,Vrije Universiteit Brussel | And 8 more authors.
PLoS ONE | Year: 2012

Aims/Hypothesis: Duct cells isolated from adult human pancreas can be reprogrammed to express islet beta cell genes by adenoviral transduction of the developmental transcription factor neurogenin3 (Ngn3). In this study we aimed to fully characterize the extent of this reprogramming and intended to improve it. Methods: The extent of the Ngn3-mediated duct-to-endocrine cell reprogramming was measured employing genome wide mRNA profiling. By modulation of the Delta-Notch signaling or addition of pancreatic endocrine transcription factors Myt1, MafA and Pdx1 we intended to improve the reprogramming. Results: Ngn3 stimulates duct cells to express a focused set of genes that are characteristic for islet endocrine cells and/or neural tissues. This neuro-endocrine shift however, is incomplete with less than 10% of full duct-to-endocrine reprogramming achieved. Transduction of exogenous Ngn3 activates endogenous Ngn3 suggesting auto-activation of this gene. Furthermore, pancreatic endocrine reprogramming of human duct cells can be moderately enhanced by inhibition of Delta-Notch signaling as well as by co-expressing the transcription factor Myt1, but not MafA and Pdx1. Conclusions/Interpretation: The results provide further insight into the plasticity of adult human duct cells and suggest measurable routes to enhance Ngn3-mediated in vitro reprogramming protocols for regenerative beta cell therapy in diabetes. © 2012 Swales et al. Source

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