Gerdal Roberto de Sousa

In vitro photodynamic inactivation of Candida spp. growth and adhesion to buccal epithelial cells.

In this study, photodynamic inactivation (PDI) was used to inhibit in vitro growth and adhesion of different Candida isolates to buccal epithelial cells (BEC). Experimental conditions were optimized and 25muM toluidine blue O (TBO) and 15min of irradiation time by light emitting diode (LED) (energy density of 180J/cm(2)) were selected due to higher reductions in cellular viability obtained after treatment. Reduction media of Log(10) 3.41 in viable cellular growth and media of 55% in the inhibition of adhesion to buccal epithelial cells were obtained. Two fluconazole resistant isolates were susceptible to PDI (Log(10) 3.54 in IB05 and Log(10) 1.95 in CG09) and a second session of this treatment for CG09 isolate inhibited cellular viability in 100%, without producing heat. The results permit to conclude that photodynamic inactivation under these experimental conditions would be a possible alternative approach to inhibit Candida spp. cellular growth and adhesion to buccal epithelial cells.

Investigation of Mast Cells in Human Gingiva Following Low-Intensity Laser Irradiation

OBJECTIVE The aims of the present study were to investigate the effect of low-intensity laser irradiation on the total number of mast cells as well as the percentage of degranulation in human gingiva. Blood vessel dilation was also evaluated. BACKGROUND DATA It has been proposed that low-intensity laser irradiation can ameliorate pain, swelling, and inflammation. In periodontal tissue, mast cells may influence either the destructive events or the defense mechanism against periodontal disease via secretion of cytokines and through cellular migration to improve the healing process. Mast cells play an important role in the inflammatory process. METHODS Twenty patients with gingival enlargement indicated for gingivectomy were selected. Gingival fragments were obtained from each patient and divided into three different groups before surgery. One fragment was removed without any irradiation. The two others were submitted to punctual irradiation with an energy density of 8 J/cm(2) at an output power of 50 mW at 36 Hz for 36 sec before gingivectomy. Nondegranulated and degranulated mast cells were counted in five areas of the gingival fragment connective tissue. Major and minor diameters of the blood vessels were also measured. RESULTS Both red and infrared radiation promoted a significant increase in mast cell degranulation compared to controls; however, no statistically significant differences (p > 0.05) were observed between the irradiated groups. No significant differences among the groups were observed regarding blood vessel size. CONCLUSION The results suggests that red and infrared wavelengths promote mast cell degranulation in human gingival tissue, although no dilation of blood vessels was observed. The effects of premature degranulation of mast cells in human tissue and the laser radiation protocol applied in this study encourage further investigations to extend these results into clinical practice.

Cryptococcus gattii: In Vitro Susceptibility to Photodynamic Inactivation

Cryptococus gattii is an emergent primary human pathogen that causes meningismus, papilledema, high intracranial pressure and focal involvement of the central nervous system in immunocompetent hosts. Prolonged antifungal therapy is the conventional treatment, but it is highly toxic, selects for resistant strains, contributes to therapy failure and has a poor prognosis. Photodynamic inactivation (PDI) offers a promising possibility for the alternative treatment of cryptococcosis. The aim of this study was to test the effectiveness of toluidine blue O (TBO) and light‐emitting diode (LED) against C. gattii strains with distinct susceptibility profile to antifungal drugs (amphotericin B: 0.015–1.0 μg mL−1; itraconazole: 0.015–2 μg mL−1; fluconazole: 4–64 μg mL−1). Using 25 μm (6.76 μg mL−1) TBO and LED energy density of 54 J cm−2 these fungal isolates presented variable susceptibility to PDI. The production of reactive oxygen species (ROS)/peroxynitrite was determined, and the catalase and peroxidase activities were measured. After PDI, high amounts of ROS/peroxynitrite are produced and higher catalase and peroxidase activities could be correlated with a lower susceptibility of C. gattii isolates to PDI. These results indicate that PDI could be an alternative to C. gattii growth inhibition, even of isolates less susceptible to classical antifungal drugs, also pointing to mechanisms related to their variable susceptibility behavior.

Monitoring the effectiveness of photodynamic therapy with periodic renewal of the photosensitizer on intracanal Enterococcus faecalis biofilms

BACKGROUND AND OBJECTIVE Photodynamic therapy (PDT) can eliminate microorganisms in a root canal. However, the parameters for disinfection remain undefined. This study assessed the effectiveness of a PDT protocol against intracanal Enterococcus faecalis biofilms. MATERIALS AND METHODS Root canals were contaminated with E. faecalis for 21 days. The instrumentation was associated to irrigation with 0.85% saline or an alternate irrigation (AI) with 5.25% NaOCl and 17% EDTA. Complementary treatments included saline/PDT and AI/PDT. Four PDT cycles were performed using a diode laser (660nm, 40mW) delivered through a tapered optical fiber. In each cycle, the root canal was filled with 1.56μM/mL methylene blue and irradiated for 150s. Microbiological samples were collected before (S1) and after (S2) instrumentation; after PDT (S3); and daily over the course of 14 days (S4-S17). Colony-forming units (CFUs) were counted, positive cultures verified, and data subjected to parametric and proportions tests. RESULTS The highest bacterial load reduction was observed in S2. In regard to S3, Saline/PDT reduced 1.3 log(10) CFU counts (p=0.000 for S2) and no CFUs were recovered after AI/PDT treatment. All canals were CFU-free on the 14th day for saline/PDT, AI and AI/PDT. Positive cultures were observed in 60% of saline-irrigated canals on the 14th day, whereas the saline/PDT, AI and AI/PDT treatments resulted in germ-free canals after 10, 5 and 2 days, respectively. CONCLUSION Our findings suggest immediate and delayed antibacterial effects using the PDT protocol tested.