Browsing by Author "Silva, H. F."
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- Evaluation of OCA diffusivity in tissues through diffuse reflection spectroscopyPublication . Martins, Inês S.; Pinheiro, M. R.; Silva, H. F.; Tuchin, V. V.; Oliveira, Luís M.The evaluation of the diffusion properties of optical clearing agents in biological tissues, which are necessary to characterize the transparency mechanisms, has been traditionally made using ex vivo tissues. With the objective of performing such evaluation in vivo, this study was made to evaluate and compare those properties for propylene glycol in skeletal muscle, as obtained with the collimated transmittance and diffuse reflectance kinetics. The diffusion time and the diffusion coefficient of propylene glycol in the muscle that were calculated both from transmittance and reflectance kinetics presented a deviation of 0.8%, a result that opens the possibility to use such a method in vivo.
- Spectroscopic detection of pigments in tissues: correlation with tissue aging and cancer developmentPublication . Oliveira, Luís M.; Goncalves, T. M.; Botelho, A. R.; Martins, I. S.; Silva, H. F.; Carneiro, I.; Carvalho, S.; Henrique, R.; Tuchin, V. V.The direct calculation of the absorption coefficient spectra of various tissues from spectral measurements allowed to retrieve the contents of melanin and lipofuscin. In the rabbit brain cortex, 1.8 times higher melanin content is explained by the neuron degeneration process. Similar melanin and lipofuscin contents were found in the rabbit pancreas as a result of the tissue aging process. The conversion of 83 % of the melanin in the human normal kidney into lipofuscin in the cancer kidney indicates that lipofuscin can be considered a kidney cancer marker in humans.