RENATO ARAÚJO PRATES

RENATO ARAÚJO PRATES

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Desenvolvimento de metodologia para o estudo do efeito fotodinâmico em infecções fúngicas
2012 - SILVA, LARISSA S. da; PRATES, RENATO A.
Effect of virulence factors on the photodynamic inactivation of Cryptococcus neoformans
2013 - PRATES, RENATO A.; FUCHS, BETH B.; MIZUMO, KAZUE; NAQVI, QURAT; KATO, ILKA T.; RIBEIRO, MARTHA S.; MYLONAKIS, ELEFTHERIOS; TEGOS, GEORGE P.; HAMBLIN, MICHAEL R.
Opportunistic fungal pathogens may cause an array of superficial infections or serious invasive infections, especially in immunocompromised patients. Cryptococcus neoformans is a pathogen causing cryptococcosis in HIV/AIDS patients, but treatment is limited due to the relative lack of potent antifungal agents. Photodynamic inactivation (PDI) uses the combination of non-toxic dyes called photosensitizers and harmless visible light, which produces singlet oxygen and other reactive oxygen species that produce cell inactivation and death. We report the use of five structurally unrelated photosensitizers (methylene blue, Rose Bengal, selenium derivative of a Nile blue dye, a cationic fullerene and a conjugate between poly-L-lysine and chlorin(e6)) combined with appropriate wavelengths of light to inactivate C. neoformans. Mutants lacking capsule and laccase, and culture conditions that favoured melanin production were used to probe the mechanisms of PDI and the effect of virulence factors. The presence of cell wall, laccase and melanin tended to protect against PDI, but the choice of the appropriate photosensitizers and dosimetry was able to overcome this resistance.
Concepts and principles of photodynamic therapy as an alternative antifungal discovery platform
2012 - TEGOS, GEORGE; DAI, TIANHONG; FUCHS, BETH B.; COLEMAN, JEFFREY J.; PRATES, RENATO A.; ASTRAKAS, CHRISTOS; DENIS, TYLER G.S.; RIBEIRO, MARTHA S.; MYLONAKIS, ELEFTHERIOS; HAMBLIN, MICHAEL R.
Influence of multidrug efflux systems on methylene blue-mediated photodynamic inactivation of Candida albicans
2011 - PRATES, RENATO A.; KATO, ILKA T.; RIBEIRO, MARTHA S.; TEGOS, GEORGE P.; HAMBLIN, MICHAEL R.
The irradiation parameters investigation of photodynamic therapy on yeast cells
2008 - PRATES, RENATO A.; SILVA, ERIQUES G. da; YAMADA JUNIOR, AECIO M.; SUZUKI, LUIS C.; PAULA, CLAUDETE R.; RIBEIRO, MARTHA S.
It has been proposed that photodynamic therapy (PDT) can inactivate microbial cells. A range of photosensitizers and light sources were reported as well as different fluence parameters and dye concentrations. However, much more knowledge regarding to the role of fluences, irradiation time and irradiance are required for a better understanding of the photodynamic efficiency. The aims of this study were to investigate the role of light parameters on the photoinactivation of yeast cells, and compare cell survivors in different growing phases following PDT. To perform this study, a suspension (106cfu/mL) of Candida albicans ATCC-90028 was used in log and stationary-phase. Three irradiances 100mW/cm2, 200mW/cm2 and 300mW/cm2 were compared under 3min, 6min and 9min of irradiation, resulting in fluences of 18, 36, 54, 72,108 and 162J/cm2. The light source used was a laser emitting at 660nm with output power of 30, 60 and 90mW. As photosensitizer, 100μΜ methylene blue was used. PDT was efficient against yeast cells (6 log reduction) in log and stationary-phase. Neither photosensitizer nor light alone presented any reduction of cell viability. The increase of irradiance and time of irradiation showed a clearly improvement of cell photoinactivation. Interestingly, the same fluences in different irradiances presented dissimilar effects on cell viability. The irradiance and time of irradiation are important in PDT efficiency. Fluence per se is not the best parameter to compare photoinativation effects on yeast cells. The growing-phases presented the same susceptibility under C. albicans photoinactivation.
Photodynamic therapy can kill Cryptococcus neoformans in in vitro and in vivo models
2009 - PRATES, RENATO A.; SILVA, ERIQUES G. da; CHAVES, PRISCILA F.; SANTOS, ANTONIO J.S.; PAULA, CLAUDETE R.; RIBEIRO, MARTHA S.