Photodynamic inactivation of a multispecies biofilm using Photodithazine(®) and LED light after one and three successive applications

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Radiographic assessment of potodynamic therapy as an adjunctive treatment on induced periodontitis in immunosupressed rats

OBJECTIVE: The aim of this study was to assess radiographically the effect of photodynamic therapy (PDT) as an adjunctive treatment to scaling and root planing (SRP) on induced periodontitis in dexamethasone-induced immunosuppressed rats. MATERIAL AND METHODS: The animals were divided into 2 groups: ND group (n=60): saline treatment; D group (n=60): dexamethasone treatment. In both ND and D groups, periodontal disease was induced by the placement of a ligature in the left first mandibular molar. After 7 days, ligature was removed and all animals received SRP, being divided according to the following treatments: SRP: saline and PDT: phenothiazinium dye (TBO) plus laser irradiation. Ten animals per treatment were killed at 7, 15 and 30 days. The distance between the cementoenamel junction and the height of the alveolar bone crest in the mesial surface of the mandibular left first molars was determined in millimeters in each radiograph. he radiographic values were analyzed statistically by ANOVA and Tukey's test at a p value <0.05. RESULTS: Intragroup radiographic assessment (ND and D groups) showed that there was statistically signifcant less bone loss in the animals treated with PDT in all experimental periods compared to those submitted to SRP. Intergroup radiographic analysis (ND and D groups) demonstrated that there was greater bone loss in the ND group treated with SRP compared to the D group treated with PDT at 7 and 30 days. CONCLUSION: PDT was an effective adjunctive treatment to SRP on induced periodontitis in dexamethasone-induced immunosuppressed rats.

Seleção de genótipos de cana-de-açúcar para acúmulo de protoporfirina ix com uso de herbicidas inibidores da protox

O objetivo do presente trabalho foi selecionar genótipos de cana-de-açúcar por meio de inibidores da PROTOX e antioxidantes para indução do acúmulo de protoporfirina IX (PROTO IX) e/ou de seus precursores em plantas. Esses compostos podem ser utilizados como agentes sensibilizantes em terapia fotodinâmica (TFD), os quais possibilitam uma fonte de baixo custo para o tratamento de neoplasias e carcinomas. O experimento foi montado em câmara climatizada, com aplicação de nove tratamentos (1. oxyfluorfen + glutamato monossódico + vitaminas C e E; 2. oxyfluorfen + glutamato monossódico + vitaminas C e E + ácido levulênico; 3. oxyfluorfen; 4. carfentrazone + glutamato monossódico + vitaminas C e E; 5. carfentrazone + glutamato monossódico + vitaminas C e E + ácido levulênico; 6. carfentrazone; 7. testemunha + vitaminas C e E; 8. testemunha + vitaminas C e E + ácido levulênico; e 9. testemunha) em oito genótipos de cana-de-açúcar (PO933499, RB806043, RB470355, PO830698, SP701143, PO901387, PO894414 e SP903414), dispostos em esquema fatorial 9 x 8, com quatro repetições. As repetições constituíram-se de folhas (20 cm) destacadas de cada genótipo, sendo estas pulverizadas com os tratamentos mencionados, em simulador estacionário. Foram realizadas avaliações visuais de controle aos 2 DAA (dias após aplicação) e, no fim do estudo, determinações analíticas via extração da biomassa fresca, verificando os teores de protoporfirina IX por cromatografia líquida de alta eficiência. Os resultados mostraram que em curto prazo foram detectados aumentos significativos nas concentrações de PROTO IX para os genótipos RB470355 e SP903414 submetidos ao tratamento 2 e para o genótipo SP701143 submetido ao tratamento 8, indicando que eles podem ser utilizados como fontes acumuladoras de protoporfirina IX.

Effectiveness of Photogem (R) activated by LED on the decontamination of artificial carious bovine dentin

The aim of this study was the evaluation of the effectiveness of photodynamic therapy on the decontamination of artificially induced carious bovine dentin, using Photoge(R) as the photosensitizer agent and an LED device as a light source. Dentin samples obtained from bovine incisors were immersed in sterile broth supplemented by Lactobacillus acidophillus 10(8) colony formation units (CFU) and Streptococcus mutans 10 8 CFU. Different concentrations of photosensitizer, PA = 1 mg/ml, PB = 2 mg/ml, and PC = 3 mg/ml, and two fluences, D = 24 J/cm(2) and D = 48 J/cm(2), were investigated. After CFU counting per milligram of carious dentin and statistical analysis, we observed that the photodynamic therapy (PDT) parameters used were effective for bacterial reduction in the in vitro model under study. The best result was achieved with the application of Photoge(R) at 2 mg/ml and photoactivated under 24 J/cm(2) showing a survival factor of 0.14. At higher photosensitizer concentrations, a higher dark toxicity was observed. We propose a simple mathematical expression for the determination of PDT parameters of photosensitizer concentration and light fluence for different survival factor values. Since LED devices are simpler and cheaper compared to laser systems, it would be interesting to verify their efficacy as a light source in photodynamic therapy for the decontamination of carious dentin.

Lethal photosensitization and guided bone regeneration in treatment of peri-implantitis: an experimental study in dogs

The purpose of this study was to evaluate the effect of lethal photosensitization and guided bone regeneration (GBR) on the treatment of ligature-induced peri-implantitis in different implant surfaces. The treatment outcome was evaluated by clinical and histometric methods. A total of 40 dental implants with four different surface coatings (10 commercially pure titanium surface (cpTi); 10 titanium plasma-sprayed (TPS); 10 acid-etched surface; 10 surface-oxide sandblasted) were inserted into five mongrel dogs. After 3 months, the animals with ligature-induced peri-implantitis were subjected to surgical treatment using a split-mouth design. The controls were treated by debridment and GBR, while the test side received an additional therapy with photosensitization, using a GaAlAs diode laser, with a wavelength of 830 nm and a power output of 50 mW for 80 s (4 J/cm(2)), and sensitized toluidine blue O (100 mu g/ml). The animals were sacrificed 5 months after therapy. The control sites presented an earlier exposition of the membranes on all coating surfaces, while the test group presented a higher bone height gain. Re-osseointegration ranged between 41.9% for the cpTi surface and 31.19% for the TPS surface in the test sites; however differences were not achieved between the surfaces. The lethal photosensitization associated with GBR allowed for better re-osseointegration at the area adjacent to the peri-implant defect regardless of the implant surface.

Evaluation of chitosan gel as antibiotic and photosensitizer delivery

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Diffusion analysis of one photosensitizer in bovine teeth using fluorescence optical imaging

Some photosensitizers (PSs) used for PACT (Antimicrobial Photodynamic Therapy) show an affinity for bacterial walls and can be photo-activated to cause the desired damage. However, on dentine bacterias may be less susceptible to PACT as a result of limited penetration of the PS. The aim of this study was to evaluate the diffusion of one PS based on hematoporphyrin on dentine structures. Twelve bovine incisors were used. Class III cavities (3 x 3 x 1 mm) were prepared on the mesial or distal surfaces using a diamond bur. Photogem (R) solution at 1 mg/mL (10 uL for each cavity) was used. The experimental Groups were divided according to thickness of dentine remaining and etched or no-etched before the PS application. The fluorescence excitation source was a VelScope (R) system. For image capture a scientific CCD color camera PixelFly (R) was coupled to VelScope. For image acquisition and processing, a computational routine was developed at Matlab (R). Fick's Law was used to obtain the average diffusion coefficient of PS. Differences were found between all Groups. The longitudinal temporal diffusion was influenced by the different times, thickness and acid etching.

Singlet Oxygen Generation Enhanced by Silver-Pectin Nanoparticles

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Terapêutica no carcinoma de células escamosas cutâneo em gatos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Indocyanine green nanoparticles useful for photomedicine

Objective: the aim of this study was to evaluate the potential application of biodegradable nanoparticles (NPs) containing indocyanine green (ICG) in photodynamic therapy (PDT). Methods: Important parameters, such as particle size and external morphology, were established by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Also, drug encapsulation efficiency and in vitro release behavior were evaluated by spectroscopic methods. Results: the particles are spherical in shape, they exhibit an 817-nm diameter, and they have a low tendency to aggregate. The loading efficiency was 65%. ICG photophysical parameters showed a bathocromic shift in ICG-loaded nanoparticles (ICG-NP). Analysis of the cell P388-D1 in the presence of the ICG-NP by SEM showed that the majority of the nanoparticles were uptaken by phagocytic cells after 2 h of incubation. After laser irradiation photodamage was observed in P388-D1 cells where ICG-NPs had been uptaken by phagocytic cells. Conclusion: Polymeric NPs work as an efficient drug delivery system for PDT drugs, and this approach can be used in the administration of amphiphilic photosensitizers in the treatment of neoplasic cells.

Treatment of ligature-induced peri-implantitis by lethal photosensitization and guided bone regeneration: A preliminary histologic study in dogs

Background: the purpose of this pilot study was to evaluate the healing potential and reosseointegration in ligature-induced peri-implantitis defects adjacent to various dental implant surfaces following lethal photosensitization.Methods: A total of 36 dental implants with 4 different surface coatings (9 commercially pure titanium surface [CPTi]; 9 titanium plasma-sprayed [TPS]; 9 hydroxyapatite [HA]; and 9 acid-etched [AE]) were inserted in 6 male mongrel dogs 3 months after extraction of mandibular premolars. After a 2-month period of ligature-induced peri-implantitis and 12 months of natural peri-implantitis progression, only 19 dental implants remained. The dogs underwent surgical debridement of the remaining dental implant sites and lethal photosensitization by combination of toluidine blue O (100 mug/ml) and irradiation with diode laser. All exposed dental implant surfaces and bone craters were meticulously cleaned by mechanical means, submitted to photodynamic therapy, and guided bone regeneration (GBR) using expanded polytetrafluoroethylene (ePTFE) membranes. Five months later, biopsies of the implant sites were dissected and prepared for ground sectioning and analysis.Results: the percentage of bone fill was HA: 48.28 +/- 15.00; TPS: 39.54 +/- 12.34; AE: 26.88 +/- 22.16; and CPTi: 26.70 +/- 16.50. The percentage of reosseointegration was TPS: 25.25 +/- 11.96; CPTi: 24.91 +/- 17.78; AE: 17.30 +/- 15.41; and HA: 15.83 +/- 9.64.Conclusion: These data suggest that lethal photosensitization may have potential in the treatment of peri-implantitis.

Chemiluminescence as a PDT light source for microbial control

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phototoxic effect of curcumin on methicillin-resistant Staphylococcus aureus and L929 fibroblasts

Photodynamic therapy has been investigated as an alternative method of killing pathogens in response to the multiantibiotic resistance problem. This study evaluated the photodynamic effect of curcumin on methicillin-resistant Staphylococcus aureus (MRSA) compared to susceptible S. aureus (MSSA) and L929 fibroblasts. Suspensions of MSSA and MRSA were treated with different concentrations of curcumin and exposed to light-emitting diode (LED). Serial dilutions were obtained from each sample, and colony counts were quantified. For fibroblasts, the cell viability subsequent to the curcumin-mediated photodynamic therapy was evaluated using the MTT assay and morphological changes were assessed by SEM analysis. Curcumin concentrations ranging from 5.0 to 20.0 μM in combination with any tested LED fluences resulted in photokilling of MSSA. However, only the 20.0 μM concentration in combination with highest fluence resulted in photokilling of MRSA. This combination also promoted an 80% reduction in fibroblast cell metabolism and morphological changes were present, indicating that cell membrane was the main target of this phototherapy. The combination of curcumin with LED light caused photokilling of both S. aureus strains and may represent an alternative treatment for eradicating MRSA, responsible for significantly higher morbidity and mortality and increased healthcare costs in institutions and hospitals. © 2012 Springer-Verlag London Ltd.

Nanotechnology-based drug delivery systems for treatment of hyperproliferative skin diseases - a review

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Recent mouse and rat methods for the study of experimental oral candidiasis

The Candida genus expresses virulence factors that, when combined with immunosuppression and other risk factors, can cause different manifestations of oral candidiasis. The treatment of mucosal infections caused by Candida and the elucidation of the disease process have proven challenging. Therefore, the study of experimentally induced oral candidiasis in rats and mice is useful to clarify the etiopathology of this condition, improve diagnosis, and search for new therapeutic options because the disease process in these animals is similar to that of human candidiasis lesions. Here, we describe and discuss new studies involving rat and mouse models of oral candidiasis with respect to methods for inducing experimental infection, methods for evaluating the development of experimental candidiasis, and new treatment strategies for oral candidiasis. © 2013 Landes Bioscience.