PEDRO ARTHUR AUGUSTO DE CASTRO

Projetos de Pesquisa
Unidades Organizacionais
Cargo

Filtros

2018 - 201912020 - 20221
Limpar filtros

Configurações

Orientador: Denise Maria Zezell ×

Resultados de Busca

Agora exibindo 1 - 2 de 2
  • Nenhuma Miniatura disponível
    Tese IPEN-doc 29223
    Chemometrics of biological tissues using infrared spectroscopy
    2022 - CASTRO, PEDRO A.A. de
    Vibrational spectroscopy techniques have been considered for the diagnosis of diseases. In particular, Fourier transforms infrared spectroscopy (FTIR) is an optical method widely adopted in biomedical research. This is because FTIR images allow the collection of various molecular information enabling a correlation between spectral characteristics and structural changes. Incorporating qualitative and quantitative aspects is essential to implementing a chemometric procedure that transcribes spectral variance into meaningful information. In the case of burns, the degree of tissue damage will strongly depend on several factors, such as severity, depth, and size, which influence the healing process. Laser scar treatment has been used for decades for post-healing remodeling. However, conventional laser techniques may not wholly normalize mature scar tissue, and a preventive approach to laser exposure during wound healing has emerged. Early intervention has already been investigated in several clinical studies, but there is no consensus. Therefore, the objectives of this study were; to investigate FTIR in biological tissue analysis to provide better chemometric strategies; to study the feasibility of FTIR to establish a profile of the skin and bone tissue, and to evaluate the effect of laser on wound healing and the development of a new chemometric methodology for automatic digital dewaxing. To this end, thermal injuries were performed on the back of Wistar rats by applying water vapor at 90ºC for 12s. Subsequently, on day three post-burn, laser irradiation was performed. In the laser procedure, 3 protocols were adopted: 1) Er:glass (SellasEvo®) with 3025FPA, 100mJ, 3s; 2) LLT with red laser with = 660nm, power 40mW; 3) Combination of the two lasers with the previous parameters. Then, a histological and chemometric analysis was performed. For the chemometric evaluation of the data, an analysis protocol was developed based on a pre-processing using OCTAVVS followed by implementing a baseline, threshold, and application of PCA. From that point, the images are classified, they can be normalized and go through the Fuzzy C-means (FCM) technique to determine the spectral differences. All-laser groups demonstrate a shrinkage of the wound region in the histopathological findings. Er:Glass, showed a smaller retraction area and less epithelium recovery. The PBM group has a dense crust. Both treatments demonstrate intense shrinkage and more consistent recovery of the epidermis. In the FCM, three trends occur 1) in the range of 900-950 cm-1 it has a significantly reduced amplitude in the control group; 2) in the range of 1200-1250 cm-1 the control group has a similar amplitude demonstrating bands of sensitive markers; and 3) the amide regions provide various spectral markers. The control group, as expected, remains with minimal changes in this FTIR region. On the other hand, in the PBM group, there is a shift from 1660 to 1679 cm-1, which may correspond to changes in the molecular structure of a protein in the context of type I collagen. FTIR is a valuable alternative for tissue research on a biochemical level through fingerprints that can be translated into morphological features.
  • Nenhuma Miniatura disponível
    Dissertação IPEN-doc 24678
    Espectroscopia de absorção no infravermelho em pele queimada: avaliação de potenciais biomarcadores para o reparo tecidual
    2018 - CASTRO, PEDRO A.A. de
    Uma caracterização bioquímica eficiente da cicatrização das feridas por queimadura pode melhorar a rotina clínica para a ajustar os tratamento dos pacientes. Considerando a dificuldade de monitoramento de cicatrização, a espectroscopia no infravermelho por transformada de Fourier acoplado com o acessório de Reflexão Total Atenuada (ATR-FTIR) é uma técnica analítica a qual tem demonstrado capacidade de prover biomarcadores espectrais no materiais biológicos. Esse estudo avaliou a capacidade de usar ATR-FTIR para classificar a pele queimada com o intuito de monitorar o reparo tecidual em pacientes. Ratos Wistar com pele queimada foram avaliados pela espectroscopia ATR-FTIR nos dias 3, 7, 14 e 21 após a queimadura e comparados com amostras de grupos sadios. Os espectros obtidos foram separados nas regiões entre 900 a 1800 cm-1 e entre 2800 a 3000 cm-1 para posterior adequação quimiométrica. Avaliou-se as amplitudes das derivadas de segunda ordem dos espectros como parâmetro de discriminação, nos quais demonstraram diferenças significativas para os grupos não queimados com controle e entre grupos de queimadura usando Glicogênio (1030 cm-1), Amida I (1628 cm-1), Amida II (1514 cm-1), Colágeno em 1281 cm-1 e Colágeno em 1336 cm-1. Esses resultados indicam que ATR-FTIR é sensível para detectar os estágios de reparo tecidual e pode futuramente ser um instrumento auxiliar para a rotina clínica.