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Doctoral Thesis
DOI
Document
Author
Full name
Daniel Riani Gotardelo
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2019
Supervisor
Committee
Soares, Carlos Roberto Jorge (President)
Peroni, Cibele Nunes
Rodas, Andrea Cecilia Dorion
Soares, Deyze Alencar
Title in Portuguese
Determinação dos níveis de porfirinas fecais por espectroscopia de fluorescência em indivíduos com câncer de próstata
Keywords in Portuguese
câncer de próstata
espectroscopia de fluorescência
fezes
porfirinas
Abstract in Portuguese
Modelos experimentais de câncer de próstata demonstraram níveis aumentados de protoporfirina IX (PpIX) no sangue e nas fezes de camundongos, fazendo com que a quantificação dessa molécula pudesse ser aventada para a identificação desse tipo de tumor. Nesse estudo do tipo caso-controle, a autofluorescência de porfirinas em fezes humanas foi analisada usando espectroscopia de fluorescência em pacientes com câncer de próstata e controles. Dados sociodemográficos, amostras sanguíneas para determinação dos níveis de PSA (antígeno prostático específico) e amostras de fezes para quantificação de porfirinas foram obtidas após consentimento dos pacientes. Recrutaram-se 18 pacientes em amostra calculada a partir dos estudos de referência. Realizou-se varredura para encontrar o melhor pico espectrofotométrico a partir de diversas diluições acetona/fezes. Primeiramente, 3 mililitros de acetona de grau analítico foram adicionados a 0,3 gramas de fezes e a mistura foi macerada e centrifugada a 4.000 rotações por minuto durante 15 minutos. O sobrenadante foi analisado espectroscopicamente. Os espectros de emissão a 550-750 nm foram obtidos excitando as amostras a 405 nm. Variáveis sociodemográficas foram analisadas e evidenciaram homogeneidade entre os grupos estudados. Um contraste significativo entre as amostras de indivíduos normais e oncológicos foi estabelecido na região espectral de 670-675 nm (p = 0,000127), o que corresponde a um aumento significativo de porfirinas fecais em pacientes com câncer. Não houve correlação estatisticamente significativa entre os níveis de PSA e as porfirinas fecais (R = -0,0221). Neste estudo preliminar realizado em seres humanos, os resultados mostram um método simples e não invasivo para avaliar as porfirinas fecais, que têm o potencial de funcionar como um biomarcador tumoral em pacientes com câncer de próstata. Essa abordagem poderia aumentar a sensibilidade e a especificidade do teste de PSA.
Title in English
Determination of faecal porphyrin levels by fluorescence spectroscopy in individuals with prostate cancer
Keywords in English
faeces
fluorescence spectroscopy
porphyrins
prostate cancer
Abstract in English
Experimental models of prostate cancer have demonstrated increased levels of protoporphyrin IX (PpIX) in the blood and faeces of mice. Hence, the quantification of these autofluorescent molecules could be hypothesized to be a potential marker for this type of tumour. In this case-control study, the autofluorescence of porphyrins in human faeces from patients with prostate cancer and control subjects was analysed using fluorescence spectroscopy. Socio-demographic data, blood samples for determination of PSA levels and faeces samples for quantification of porphyrins were obtained after consent of the patients. Eighteen patients were recruited in a sample calculated from the reference studies. Scanning was performed to determine the best spectrophotometric peak from various acetone/faecal dilutions. First, 3 mL of analytical-grade acetone was added to 0.3 g of faeces, and the mixture was macerated and centrifuged at 4000 rpm for 15 min. The supernatant was analysed spectroscopically. The emission spectra from 550 to 750 nm were obtained by exciting the samples at 405 nm. Socio-demographic variables were analyzed and showed homogeneity among the groups studied. A significant difference between the samples from control and cancer subjects was established in the spectral region of 670675 nm (p = 0.000127), which corresponds to a significant increase in faecal porphyrins in patients with cancer. There was no statistically significant correlation between PSA levels and faecal porphyrins (R = -0,0221). In this preliminary study conducted in humans, the results show a simple and non-invasive method to assess faecal porphyrins, which have the potential to function as a tumour biomarker in patients with prostate cancer. This approach has improved sensitivity and specificity over PSA testing.
 
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Publishing Date
2019-06-13
 
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