Percorrer por autor "Lopes, Carlos"
A mostrar 1 - 3 de 3
Resultados por página
Opções de ordenação
- P53 and Cancer-Associated Sialylated Glycans Are Surrogate Markers of Cancerization of the Bladder Associated with Schistosoma haematobium InfectionPublication . Santos, Júlio; Fernandes, Elisabete; Ferreira, José Alexandre; Lima, Luís; Tavares, Ana; Peixoto, Andreia; Parreira, Beatriz; Costa, José Manuel Correira da; Brindley, Paul J; Lopes, Carlos; Santos, LúcioBACKGROUND: Bladder cancer is a significant health problem in rural areas of Africa and the Middle East where Schistosoma haematobium is prevalent, supporting an association between malignant transformation and infection by this blood fluke. Nevertheless, the molecular mechanisms linking these events are poorly understood. Bladder cancers in infected populations are generally diagnosed at a late stage since there is a lack of non-invasive diagnostic tools, hence enforcing the need for early carcinogenesis markers. METHODOLOGY/PRINCIPAL FINDINGS: Forty-three formalin-fixed paraffin-embedded bladder biopsies of S. haematobium-infected patients, consisting of bladder tumours, tumour adjacent mucosa and pre-malignant/malignant urothelial lesions, were screened for bladder cancer biomarkers. These included the oncoprotein p53, the tumour proliferation rate (Ki-67>17%), cell-surface cancer-associated glycan sialyl-Tn (sTn) and sialyl-Lewisa/x (sLea/sLex), involved in immune escape and metastasis. Bladder tumours of non-S. haematobium etiology and normal urothelium were used as controls. S. haematobium-associated benign/pre-malignant lesions present alterations in p53 and sLex that were also found in bladder tumors. Similar results were observed in non-S. haematobium associated tumours, irrespectively of their histological nature, denoting some common molecular pathways. In addition, most benign/pre-malignant lesions also expressed sLea. However, proliferative phenotypes were more prevalent in lesions adjacent to bladder tumors while sLea was characteristic of sole benign/pre-malignant lesions, suggesting it may be a biomarker of early carcionogenesis associated with the parasite. A correlation was observed between the frequency of the biomarkers in the tumor and adjacent mucosa, with the exception of Ki-67. Most S. haematobium eggs embedded in the urothelium were also positive for sLea and sLex. Reinforcing the pathologic nature of the studied biomarkers, none was observed in the healthy urothelium. CONCLUSION/SIGNIFICANCE: This preliminary study suggests that p53 and sialylated glycans are surrogate biomarkers of bladder cancerization associated with S. haematobium, highlighting a missing link between infection and cancer development. Eggs of S. haematobium express sLea and sLex antigens in mimicry of human leukocytes glycosylation, which may play a role in the colonization and disease dissemination. These observations may help the early identification of infected patients at a higher risk of developing bladder cancer and guide the future development of non-invasive diagnostic tests.
- Power transformers diagnosis: Status evaluationPublication . Nogueira, Teresa; Lopes, Carlos; Felgueiras, Carlos; Quadrado, Jose CarlosThe reliability of the electrical grid depends on the availability and performance of crucial components such as power transformers. A failure in these expensive devices threatens supply energy warranty and system overhaul reliability. As transformers approach their end of life, the failure rate tends to increase and, therefore, both equipment diagnostics and working condition assessment are important to detect oncoming faults. In this work, we develop a state assessment methodology, able to evaluate power transformers health condition. The study is about the transformer operation analysis and the associated status index calculation. This index value classifies the transformer general operation, according to the information of five partial indexes, reflecting the work conditions of most critical equipment: insulating oil and paper, winding and bushings. This contribution also presents an extensive transformer state analysis, backed up by in-service equipment.
- Sequence alignment: Comparative analysis of algorithms in KRAS genetic mutationsPublication . Pereira, Ana Rita; Lopes, Carlos; Oliveira, Catarina; Pereira, Gonçalo; Moreira, Rui; Faria, Brígida Mónica; Faria, Brigida MonicaFor this study a program was developed in Python on biological sequence alignment, considering the application of algorithms in the genetic analysis of Kristen rat sarcoma viral oncogene (KRAS) and its main mutations associated with cancer. The KRAS gene, like other genes in the same family, is responsible for encoding proteins that regulate cell proliferation, differentiation, and apoptosis. The algorithms employed include the Needleman-Wunsch algorithm as well as the Smith-Waterman algorithm and the Basic Local Alignment Search Tool (BLAST). The algorithms for multiple sequence alignment help to understand the function, evolution, and variability of biological sequences, significantly contributing to advances in genomics and proteomics. The objectives of this study are to apply algorithms for the effective alignment of biological sequences, compare the non-mutated KRAS sequence with principal mutations associated with cancer development, delineate and justify the selection of the algorithms used, assess their computational complexity, and facilitate 3D visualization of the sequences. Development of a program - BioAlign - in Python, with various functions including upload and visualization of sequences; use of different algorithms for global and local alignment; BLAST search; algorithms complexity analysis; obtaining the nucleotides positions; obtaining subsequence and its position; phylogenetic analysis; histogram visualization of sequence length and 3D structure visualization. The program is capable of analyzing and comparing the provided sequences using both local and global algorithms. The execution time among the three main algorithms differs, with the BLAST algorithm notably slower in returning results. This fact may be due to several factors, such as the complexity of the algorithm itself, the internet speed, and the response time of the NCBI website. The development of the BioAlign program indeed allows to address the proposed objectives. Furthermore, the completion of this project has enhanced proficiency in utilizing the Python programming language, demonstrating significant skill development.