Browsing by Author "Ramos, S."
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- Differential expression of the eukaryotic release factor 3 (eRF3/GSPT1) according to gastric cancer histological typesPublication . Malta-Vacas, Joana; Aires, C.; Costa, P.; Conde, A. R.; Ramos, S.; Martins, A. P.; Monteiro, C.; Brito, MiguelBackground: There are now several lines of evidence to suggest that protein synthesis and translation factors are involved in the regulation of cell proliferation and cancer development. Aims: To investigate gene expression patterns of eukaryotic releasing factor 3 (eRF3) in gastric cancer. Methods: RNA was prepared from 25 gastric tumour biopsies and adjacent non-neoplastic mucosa. Real time TaqMan reverse transcription polymerase chain reaction (RT-PCR) was performed to measure the relative gene expression levels. DNA was isolated from tumour and normal tissues and gene dosage was determined by a quantitative real time PCR using SYBR Green dye. Results: Different histological types of gastric tumours were analysed and nine of the 25 tumours revealed eRF3/GSPT1 overexpression; moreover, eight of the 12 intestinal type carcinomas analysed overexpressed the gene, whereas eRF3/GSPT1 was overexpressed in only one of the 10 diffuse type carcinomas (Kruskal-Wallis Test; p , 0.05). No correlation was found between ploidy and transcript expression levels of eRF3/GSPT1. Overexpression of eRF3/GSPT1 was not associated with increased translation rates because the upregulation of eRF3/GSPT1 did not correlate with increased eRF1 levels. Conclusions: Overexpression of eRF3/GSPT1 in intestinal type gastric tumours may lead to an increase in the translation efficiency of specific oncogenic transcripts. Alternatively, eRF3/GSPT1 may be involved in tumorigenesis as a result of its non-translational roles, namely (dis)regulating the cell cycle, apoptosis, or transcription.
- Importância da citologia na deteção de lesões do endométrioPublication . Santos, B.; Oliveira, C.; Ramos, S.; Gomes, N.; Oliveira, Daniel; Silva, A. S.; Adriano, A.; Luís, A.; Mendonça, PaulaO presente estudo reporta a citologia de uma mulher de 66 anos, que apresenta um epitélio atrófico com fundo inflamatório. Identificaram-se agregados tridimensionais de células glandulares com sobreposição celular, anisocariose, aumento nuclear, hipercromasia moderada, presença de nucléolos e cromatina grosseira, irregularmente distribuída. O diagnóstico citológico foi de células glandulares atípicas sem outra especificação, com inflamação. Posteriormente, realizou-se uma biópsia cujo diagnóstico foi carcinoma endometrial de tipo endometrióide. A paciente foi submetida a histerectomia total com anexectomia bilateral, confirmando-se o diagnóstico da biópsia. O diagnóstico de células glandulares atípicas é definido pela presença de células glandulares com alterações que ultrapassam as reativas/reparativas, mas sem características inequívocas de adenocarcinoma. No follow-up a maioria destes casos representa uma condição benigna. No entanto, um subconjunto significativo revela uma lesão pavimentosa de alto grau ou uma lesão neoplásica glandular, não sendo incomum a associação entre o diagnóstico de células glandulares atípicas e a presença de adenocarcinomas do colo uterino, endométrio, ovário e trompa de Falópio. A citologia tem uma especificidade relativamente elevada na deteção de patologia endometrial, apresentando um papel preponderante no diagnóstico de neoplasias. Neste caso, o reconhecimento de células glandulares atípicas, conduziu ao diagnóstico de carcinoma endometrial.
- Polyglycine expansions in eRF3/GSPT1 are associated with gastric cancer susceptibilityPublication . Brito, Miguel; Malta-Vacas, Joana; Carmona, Bruno; Aires, C.; Costa, P.; Martins, A. P.; Ramos, S.; Conde, A. R.; Monteiro, C.Gastric cancer remains a major cause of death in the developed countries, and a large percentage is still genetically unexplained. Because of their major role in cell survival, mutations in translation factors and altered expression of these genes have been associated with cancer development. Apart from its role in translation termination, the eukaryotic translation release factor 3 (eRF3) is involved in several critical cellular processes, such as cell cycle regulation, cytoskeleton organization, and apoptosis. The aim of this study was to evaluate eRF3/GSPT1 gene as a potential genetic susceptibility associated locus for gastric cancer, analyzing a stable GGC expansion in exon 1 encoding a polyglycine tract in the N-terminal domain of the protein. DNA was obtained from 139 patients with gastric cancer and from 100 individuals of a healthy control population. The GGC expansion was amplified by PCR and the number of repeats determined by genotyping in an automatic sequencer. There are five known alleles encoding from 8 to 12 glycines. The most common allele encodes 10 glycines. The 12-Gly allele was detected exclusively in the cancer patients (allelic frequency = 5%). Regardless of the genotype, patients with the 12-Gly allele had a 20-fold increased risk for gastric cancer. We also detected a single-base alteration in the gene (G274T) although no correlation with cancer development has been found. Thus, our results show that the GGC expansion may have a potential role in regulating eRF3/GSPT1 expression and/or changing the protein function that can lead to gastric cancer development.
- Simulation of the Magnetic Induction Vector of a Magnetic Core to be Used in FFC NMR RelaxometryPublication . Roque, António; Ramos, S.; Barão, J.; Machado, M.; Sousa, D. M.; Margato, Elmano; Maia, J.This paper is a contribution for the assessment and comparison of magnet properties based on magnetic field characteristics particularly concerning the magnetic induction uniformity in the air gaps. For this aim, a solver was developed and implemented to determine the magnetic field of a magnetic core to be used in Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometry. The electromagnetic field computation is based on a 2D finite-element method (FEM) using both the scalar and the vector potential formulation. Results for the magnetic field lines and the magnetic induction vector in the air gap are presented. The target magnetic induction is 0.2 T, which is a typical requirement of the FFC NMR technique, which can be achieved with a magnetic core based on permanent magnets or coils. In addition, this application requires high magnetic induction uniformity. To achieve this goal, a solution including superconducting pieces is analyzed. Results are compared with a different FEM program.