Copolymeric micelles as efficient inert nanocarrier for hypericin in the photodynamic inactivation of Candida species.

Aim: To evaluate the efficacy of photodynamic inactivation (PDI) mediated by hypericin encapsulated in P-123 copolymeric micelles (P123-Hyp) alone and in combination with fluconazole (FLU) against planktonic cells and biofilm formation of Candida species Materials & methods: PDI was performed using P123-Hyp and an LED device with irradiance of 3.0 mW/cm2 . Results: Most of isolates (70%) were completely inhibited with concentrations up to 2.0 µmol/l of HYP and light fluence of 16.2 J/cm2. FLU-resistant strains had synergic effect with P123-HYP-PDI and FLU. The biofilm formation was inhibited in all species, in additional the changes in Candida morphology observed by scanning electron microscopy. Conclusion: P123-Hyp-PDI is a promising option to treat fungal infections and medical devices to prevent biofilm formation and fungal spread.

Supragingival and subgingival microbiota from patients with poor oral hygiene submitted to radiotherapy for head and neck cancer treatment.

OBJECTIVE: This case-control study aimed to evaluate the effects of conventional radiotherapy (RT) on the prevalence and populations of oral microorganisms in head and neck cancer patients who did not receive adequate preventive dental care. It was hypothesized that side effects of radiotherapy could be associated with radiation dose, microbiological aspects, and socioeconomic conditions of the patients. DESIGN: Twenty-eight dentate patients with head and neck cancer submitted to RT were included in the study. Radiation dose received varied from 4320 to 7020 cGy. Patients with the same demographic and health conditions, but no history of cancer or antineoplastic treatment were used as controls. Clinical examinations were carried out before RT, 15-22 days after starting RT, immediately after and 6 months after RT. Supra and subgingival biofilms were collected and cultivated onto selective and non-selective media. Isolates were identified by biochemical and physiological characteristics. Stimulated and unstimulated salivary flow rate and saliva buffer capacity were also determined. RESULTS: Mucositis, dermatitis, xerostomia, dysgeusia, dysphagia and candidiasis were common after starting RT and during the treatment period. Xerostomia was followed by a decrease in salivary pH and buffer capacity, which showed association with the increase of cariogenic cocci and yeast populations, which were also associated with deterioration of hygiene. Candida and family Enterobacteriaceae showed increased prevalence with RT, and were associated with the occurrence of mucositis and xerostomia. CONCLUSIONS: Modifications in oral biofilms of irradiated patients showed association with xerostomia and hygiene conditions, which reinforces the necessity of improving patient compliance to oral health care programs.

Synergism between fluconazole and methylene blue-photodynamic therapy against fluconazole-resistant Candida strains.

Photodynamic therapy (PDT) has been proved to be effective against fungi and it may be employed as a coadjutant to conventional antifungal agents, leading to a more effective microbial control minimising side effects. This work evaluates the combined effect of PDT and fluconazole against resistant Candida albicans, Candida glabrata and Candida krusei. The yeasts were submitted to methylene blue-PDT (MB-PDT) in sub-inhibitory concentrations. In the present work, MB-PDT combined with fluconazole was more efficient in the inhibition of the C. albicans and C. glabrata than each treatment alone, being possible to infer that the treatments are synergic.

Irradiação a Laser de baixa intensidade sobre cepas de Candida in vitro: In vitro / Irradiación Láser de baja intensidad en cepas de Candida: an in vitro study / Low-level laser irradiation on Candida strains

Objetivo: avaliar o efeito de parâmetros específicos da irradiação com laser de baixa intensidade sobre cepas de Candida albicans (ATCC 18804), Candida krusei (ATCC 34135) e Candida tropicalis (ATCC 13803). Metodologia: inóculos das três especies de cândida (1.5 x 106 microorganismos/ml ) foram irradiadas com um dispositivo laser infra-vermelho de Arsenato de Gálio -AsGa (TwinFlex Evolution, MMO Equipamentos Eletrônicos 660 nm, 0,5 nW), nas doses (J/cm2): 1,2 (10 seg), 3,7 (30 seg), 7,5 (1min) e 15(2 min). Após aplicação, os inóculos foram semeados em placas petri com meio de cultura Sabouraud-Dextrose e incubadas em estufa bacteriológica a 37ºC. Depois de 48 horas, realizou-se a quantificação das Unidades Formadoras de Colônias ­ UFC e analisou-se os dados estatisticamente, através dos Testes de Friedman e Wilcoxon (a =0,05). Todos os testes foram realizados em duplicata. Resultados: os valores da mediana (Q25 - Q75) obtidos na quantificação das cepas após irradiação do laser nas doses ( J/cm2) 1,2, 3,7, 7,5 e 15 foram respectivamente: 35,23 (9,15-47,64); 6,79 (1,45-6,87); 5,32 (1,39-8,15); 6,10 (1,18-11,86) e 5,13 (0,99-6,25). Estes resultados mostraram diferença significativa estatisticamente de acordo com a dose aplicada (p<0,05), no entanto, não se identificou o(s) grupo (s) que apresenta diferença significativa dentre os demais, no pós-hoc. Conclusão: alaserterapia de baixa intensidade apresentou efeito inibitório sobre cepas de Candida, sendo esta atividade alterada de acordo com a dose irradiada(AU)

Objetivo: evaluar el efecto de los parámetros específicos de la irradiación con láser de baja intensidad en cepas de Candida albicans (ATCC 18804), Candida krusei (ATCC 34135) y Candida tropicalis (ATCC 13803). Métodos: los inóculos de las tres especies de Candida (1,5 x 106 microorganismos / ml) se irradiaron con un dispositivo láser de infra-roj de GaAs-arseniato de galio (TwinFlex Evolution, MMO Electronic Equipment 660 nm, 0,5 nW) en la dosis (J/cm2) 1,2 (10 seg), 3,7 (30 seg), 7,5 (1 min) y 15 (2 min). Después de la aplicación, los inóculos se sembraron en placas de Petri con medio de cultivo de Dextrosa Sabouraud y se incubaron en incubadora bacteriológica a 37 ° C. Después de 48 horas, se produjo la cuantificación de unidades formadoras de colonias - UFC y los datos fueron analizados estadísticamente mediante la prueba de Wilcoxon y Friedman (a= 0,05). Todos los ensayos se realizaron por duplicado. Resultados: los valores medios (Q25 - Q75) obtenidos en la cuantificación de las cepas después de la irradiación con láser en la dosis (J/cm2) 1,2, 3,7, 7,5 y 15, fueron respectivamente: 35,23 (9,15-47,64) 6,79 (1,45-6,87) 5,32 (1,39 a 8,15) 6,10 (1,18-11,86) y 5.13 (0,99-6,25). Estos mostraron una diferencia estadísticamente significativa de acuerdo con la dosis aplicada (p <.05), sin embargo, no se identificaron (s) grupo (s) que presenta una diferencia significativa entre otros en lo post-hoc. Conclusiones: el tratamiento con láser de baja intensidad mostró efecto inhibitorio sobre cepas de Candida, siendo esta actividad alterada de acuerdo con la dosis irradiada(AU)

Objective: to evaluate the effect of specific parameters of low-level laser irradiation on strains of Candida albicans (ATCC 18804), Candida krusei (ATCC 34135) and Candida tropicalis (ATCC 13803). Methods: the inocula of the three Candida species (1.5 x 106 microorganisms/ml) were irradiated with a gallium-arsenide (GaAs) infrared laser device (Twinflex Evolution, MMO Electronic Equipment, 660 nm, 0.5 nW) at doses (J/cm2): 1.2 (10 sec), 3.7 (30 sec), 7.5 (1min) and 15 (2 min). Following irradiation, the inocula were grown on Petri dishes containing Sabouraud Dextrose culture medium and then incubated in bacteriological incubator at 37 °C. After 48 hours, it was quantified the number of colony-forming units (CFU) and data were statistically analyzed using Friedman's and Wilcoxon's tests (α=0.05). All tests were performed in duplicate. Results: the median values (Q25 - Q75) gathered in the quantification of the strains after laser irradiation at doses (J/cm2) 1.2, 3.7, 7.5 and 15 were, respectively: 35.23 (9,15-47,64); 6,79 (1,45-6,87); 5,32 (1,39-8,15); 6.10 (1,18-11,86) and 5.13 (0,99-6,25). These results were found to show statistically significant differences according to the dose administered (p<0.05). Nevertheless, it was not possible to identify in the post-hoc tests which group(s) showed significant difference. Conclusion: low-intensity laser therapy showed inhibitory effect on Candida strains, and such activity was altered according to the irradiated dose(AU)

Photodynamic inactivation of clinical isolates of Candida using Photodithazine®.

This study evaluated the photodynamic inactivation (PDI) mediated by Photodithazine(®) (PDZ) against 15 clinical isolates of Candida albicans, Candida glabrata and Candida tropicalis. Each isolate, in planktonic and biofilm form, was exposed to PDI by assessing a range of PDZ concentrations and light emitting diode fluences. Cell survival of the planktonic suspensions was determined by colony forming units (CFU ml(-1)). The antifungal effects of PDI against biofilms were evaluated by CFU ml(-1) and metabolic assay. Data were analyzed by non-parametric tests (α = 0.05). Regardless of the species, PDI promoted a significant viability reduction of planktonic yeasts. The highest reduction in cell viability of the biofilms was equivalent to 0.9 log10 (CFU ml(-1)) for C. albicans, while 1.4 and 1.5 log10 reductions were obtained for C. tropicalis and C. glabrata, respectively. PDI reduced the metabolic activity of biofilms by 62.1, 76.0, and 76.9% for C. albicans, C. tropicalis, and C. glabrata, respectively. PDZ-mediated PDI promoted significant reduction in the viability of Candida isolates.

Clotrimazole-loaded Eudragit® RS100 nanocapsules: preparation, characterization and in vitro evaluation of antifungal activity against Candida species.

Clotrimazole is a common choice for the treatment of vulvovaginal infections, but its low solubility and some side effects pose a challenge to its application. This work evaluated the feasibility to formulate clotrimazole-loaded cationic nanocapsules using Eudragit® RS100 and medium chain triglycerides as polymer and oily core, respectively, by the method of interfacial deposition of a preformed polymer. The physicochemical characteristics of nanocapsule formulations were evaluated at 0 day and 60 days after preparation. Particle size, zeta potential, polydispersity index, pH and drug content were stable during this period. In addition, nanocapsules were able to protect clotrimazole from photodegradation under UV radiation. By the dialysis bag diffusion technique, the nanosized formulations showed prolonged release of clotrimazole by anomalous transport and first order kinetics. A microbiological study was carried out by the microdilution method and showed that nanocapsules (mean size: 144 nm; zeta potential: +12 mV) maintained the antifungal activity of clotrimazole against Candida albicans and Candida glabrata strains susceptible and resistant to fluconazole.

In vitro photodynamic inactivation of Candida species and mouse fibroblasts with phenothiazinium photosensitisers and red light.

In the present study, the in vitro susceptibilities of five Candida spp. to photodynamic antimicrobial chemotherapy (PACT) with four phenothiazinium derivatives, methylene blue (MB), new methylene blue N (NMBN), toluidine blue O (TBO) and the novel pentacyclic phenothiazinium photosensitiser S137, in combination with red light were investigated. The efficacy of each PS was determined, initially, based on its minimal inhibitory concentration (MIC). Additionally, we evaluated the effect of the photodynamic treatment with NMBN and S137 on Candida survival and on the mouse fibroblast cell line L929. MICs varied both among PS and species and decreased with light dose increase. For most treatments (species and fluences) NMBN and S137 showed the lowest MICs. MICs for NMBN and S137 were <2.5 µM for all the Candida species when a fluence of 25 J cm⁻² was used. PACT with NMBN (fluence of 15 J cm⁻²) resulted in reductions in survival from 0.3 log (Candida krusei) to 3 logs (C. parapsilosis). PACT with S137 was more effective than with NMBN. Fluence of 15 J cm⁻² resulted in reductions in survival from 1 log (C. krusei) to 3 logs (C. parapsilosis) and fluence of 25 J cm⁻² resulted in a reduction of approximately 2 logs (C. krusei) and between 3 and 4 logs in survival of the other 4 species of Candida. In vitro relative toxicities of the phenothiazinium PS to mammalian cells exhibited a similar trend to the antifungal data, i.e. greater toxicity and phototoxicity with NMBN and S137 compared to the established PS.

Microwave irradiation as an alternative method for disinfection of denture base acrylic resins.

AIM: This study evaluated the effect of microwave irradiation as an alternative method for disinfection of different types of denture base acrylic resins. METHODS: Twenty-four samples for each conventional, microwaved and characterized heat-cured acrylic resin were made and subjected to sterilization with ethylene oxide for the groups: 1) irradiated samples; 2) non-irradiated samples; and 3) samples without yeast. Each group was subdivided according to inoculation with C. albicans, C. dubliniensis and C. tropicalis. The samples were inoculated with 100 µL of inoculum of each species of Candida and later placed in an incubator at 37 °C for 1 hr to perform the first adhesion. After this time, each well was supplemented with sterile media and the plate was once again taken to a stove for incubation at 37 °C for 6 hr. The samples were immersed in 100 mL of sterile water and irradiated with microwave at 650 W for 3 min. Control samples were considered as the non-irradiated group. After incubation for 48 hr, irradiated and non-irradiated samples were subjected to a digital colony counter. RESULTS: Control group (non-irradiated) showed microbial growth for resins and the means of ufc/mL were without statistically significant differences. Microwave irradiated samples (experimental group) promoted no viable colonies for all Candida species and types of acrylic resins. The means of ufc/mL were without statistically significant differences. CONCLUSION: Microwave irradiation was an effective method for disinfection of the acrylic resins inoculated with C. albicans, C. dubliniensis and C. tropicalis.

Susceptibilidad a fluconazol y voriconazol por el método de disfusión de cepas de candida, aisladas de hemocultivos en Maracaibo, Venezuela / Susceptibility to fluconazole and voriconazole in candida strains isolated from blood culture by disk diffusion method Maracaibo, Venezuela

Para determinar la susceptibilidad de cepas de Candida aisladas de hemocultivos en nuestro medio, se estudiaron 78 cepas obtenidas de pacientes hospitalizados en diferentes servicios del Servicio Autónomo Hospital Universitario de Maracaibo (SAHUM), Venezuela. Para la identificación de especies se usó el medio cromogénico Brilliance Candida Agar y Vitek-YBC. Adicionalmente, los cultivos fueron identificados por el método tradicional. La susceptibilidad fue determinada por el método de difusión con discos de fluconazol y voriconazol según la metodología M44-A2 del Clinical Laboratory Standard Institute. La frecuencia de las especies de Candida fue: C. parapsilosis 51,28%, C. tropicalis 15,38%, C. guilliermondii 11,54%, C. albicans 10,26% C. famata 6,41%, C. glabrata 3,85% y C. krusei 1,28%. La susceptibilidad fue de 96,15% y 100% para fluconazol y voriconazol, respectivamente. Tres de las 78 cepas, identificadas como C. albicans, C. guilliermondii y C. krusei fueron resistentes a fluconazol. Estos resultados sugieren que fluconazol y voriconazol pueden ser utilizados en el tratamiento de pacientes con candidemia en SAHUM, sin embargo, la vigilancia epidemiológica y la determinación de la susceptibilidad de Candida deben mantenerse

To determine the susceptibility of Candida strains isolated from blood cultures in Maracaibo, Venezuela, 78 strains obtained from hospitalized patients in different services of the autonomous Maracaibo University Hospital, Venezuela, were studied. Chromogenic Medium Brilliance Candida Agar and Vitek-YBC were used for species identification. In addition, cultures were assessed using the traditional identification method. Susceptibility was determined by the diffusion method with fluconazole and voriconazole disks, according to the Clinical and Laboratory Standard Institute, Document M44-A2. Frequency of the Candida species was: C. parapsilosis 51.28%, C. tropicalis 15.38%, C. guilliermondii 11.54%, C. albicans 10.26% C. famata 6.41%, C. glabrata 3.85% and C. krusei 1.28%. Susceptibility was 96.15% and 100% for fluconazole and voriconazole, respectively. Three isolates identified as C. albicans, C. guilliermondii and C. krusei were resistant to fluconazole. These results suggest that fluconazole and voriconazole can be useful in the treatment of patients with candidemia; however, epidemiological surveillance and susceptibility pattern determination of Candida must be maintained

In vitro photodynamic inactivation of Candida spp. by different doses of low power laser light.

This study evaluated the efficacy of PDT in photoinactivation of Candida species using methylene blue (MB) and irradiation with a diode laser (660nm, 40mW). Suspensions of Candida species were obtained containing 10(6)cfu/ml, transferred to 96-holes plates and exposed to 03 doses of laser light (60J/cm(2), 120J/cm(2), 180J/cm(2)) in the presence of MB. Additional suspensions were treated with only the MB, the laser light or with 0.85% saline (control groups). After the treatments, 1µl aliquot of the suspensions was plated in duplicate on SDA. The plates were incubated at 37°C for 24-48h and after this period there was the counting of colonies (cfu/ml). The three evaluated doses determined meaningful inactivation of Candida spp. (p<0.05). The 180J/cm(2) dose was the most effective, inactivating 78% of cfu/ml. At a dose of 180J/cm(2)C. albicans was the most susceptible specie. PDT has demonstrated effectiveness in the inactivation of Candida spp.

Denture stomatitis treated with photodynamic therapy: five cases.

OBJECTIVE: Photodynamic therapy (PDT) is an effective method for Candida spp. inactivation in vitro and in vivo, but as yet, no clinical trial has been conducted. This report describes 5 cases of denture stomatitis (DS) treated with PDT. STUDY DESIGN: Five subjects with clinical and microbiologic diagnosis of DS were submitted to 6 sessions of PDT 3 times a week for 15 days. In each session, patients' dentures and palates were sprayed with 500 mg/L Photogem, and, after 30 minutes of incubation, irradiated by light-emitting diode light source at 455 nm (37.5 and 122 J/cm(2), respectively). Cultures of Candida spp. from dentures and palates and standard photographs of the palates were taken at baseline (day 0), at the end of the treatment (day 15), and at follow-up time intervals (days 30 and 60). RESULTS: Four patients showed clinical resolution of DS (no inflammation) after PDT sessions, and only 1 subject demonstrated reduction in palatal inflammation. Recurrence of DS was observed in 2 patients during the follow-up period. CONCLUSIONS: PDT appears to be an alternative treatment for DS.

Extracts from Alternanthera maritima as natural photosensitizers in photodynamic antimicrobial chemotherapy (PACT).

This study investigated the effect of photodynamic antimicrobial chemotherapy (PACT) using extracts from Alternanthera maritima on the viability of Candida dubliniensis. Human infections constitute a great health problem. Several antifungal drugs are currently available, but their uses are limited by a number of factors, such as low potency, poor solubility, microbial resistance, and drug toxicity. Therefore, the search for new and more effective antimicrobial agents and the development of alternative therapies, such as PACT, are necessary. Crude hexane and ethanol extracts of A. maritima were produced. The prepared extracts presented absorption at 650-700 nm. For bioassays, 50 microL of culture medium, 50 microL of extract (25 mg/mL) or control, and 5 microL of a suspension of the microorganism to be tested (C. dubliniensis ATCC 778157 or ATCC 777, 10(7)CFU/mL) were placed in a sterile 96-well microtiter plate (well cross section=0.38 cm(2)). The contents of each well were irradiated with a 685-nm diode laser with an output power of 35 mW, which was distributed through the well cross section yielding an energy dosage of 28 J/cm(2). In each assay (n=6), one plate was subjected to irradiation, and one was not. For each active sample, the number of colony-forming units per milliliter (CFU/mL) was obtained, and data were analyzed by the Tukey test. The chemical compositions of the extracts were determined by chromatographic and spectroscopic techniques. The results suggest inhibition of the growth of C. dubliniensis when irradiated with a diode laser in the presence of hexane and ethanol extracts from A. maritima as photosensitizers. Laser irradiation alone or crude extracts at 25mg/mL did not significantly reduce the number of CFU/mL. Steroids, triterpenes, and flavonoids were identified in the analyzed extracts. In conclusion, the photoactivation of crude hexane and ethanol extracts of A. maritima by red laser radiation at 685 nm promoted an antimicrobial effect, showing that these natural products can be used as photosensitizers in PACT.

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.

Growth of Candida species on complete dentures: effect of microwave disinfection.

Microwave disinfection of complete dentures has been recommended to treat denture stomatitis in non-immune compromised patients. Oral candidiasis is a frequent manifestation of HIV infection. The objective of this study is to evaluate the effectiveness of microwave irradiation on the disinfection of complete dentures inoculated with American Type Culture Collection (ATCC) and HIV isolates of five species of Candida. Fifty dentures were made, sterilised and inoculated with the tested microorganisms (C. albicans, C. dubliniensis, C. krusei, C. glabrata and C. tropicalis). After incubation (37 degrees C/48 h), dentures were microwaved (650 W/3 min). Non-irradiated dentures were used as positive controls. Replicate aliquots of suspensions were plated at dilutions 10(-1) to 10(-4) and incubated (37 degrees C/48 h). Colony counts (cfu ml(-1)) were quantified. Dentures were also incubated at 37 degrees C for 7 days. Data were analysed with 2-way ANOVA and Tukey HSD tests (alpha = 0.05). Dentures contaminated with all Candida species showed sterilisation after microwave irradiation. All control dentures showed microbial growth on the plates. The cfu ml(-1) for C. glabrata was higher than those of C. albicans, C. dubliniensis and C. tropicalis whereas the cfu ml(-1) for C. krusei was lower. The cfu ml(-1) for clinical isolates was higher than those of ATCC yeast. Microwave irradiation for 3 min at 650 W resulted in sterilisation of all complete dentures.

Photosensitization of different Candida species by low power laser light.

The aim of this study was to evaluate the effects of the laser radiation (685 nm) associated with photosensitizers on viability of different species of Candida genus. Suspensions of Candida albicans, Candida dubliniensis, Candida krusei and Candida tropicalis, containing 10(6) viable cells per milliliter were obtained with the aid of a Neubauer's chamber. From each species, 10 samples of the cell suspension were irradiated with diode laser (685 nm) with 28 J/cm2 in the presence of methylene blue (0.1 mg/ml), 10 samples were only treated with methylene blue, 10 samples were irradiated with laser in the absence of the dye, 10 samples were treated with the dye and irradiated with laser light and 10 samples were exposed to neither the laser light nor to the methylene blue dye. From each sample, serial dilutions of 10(-2) and 10(-3) were obtained and aliquots of 0.1 ml of each dilution were plated in duplicate on Sabouraud dextrose agar. After incubation at 37 degrees C for 48 h, the number of colony-forming units (CFU/ml) was obtained and data were submitted to ANOVA and Tukey's test (p<0.05). Laser radiation in the presence of methylene blue reduced the number of CFU/ml in 88.6% for C. albicans, 84.8% for C. dubliniensis, 91.6% for C. krusei and 82.3% for C. tropicalis. Despite this, only laser radiation or methylene blue did not reduce significantly the number of CFU/ml of Candida samples, except for C. tropicalis. It could be concluded that the photo activation of methylene blue by the red laser radiation at 685 nm presented fungicide effect on all Candida species studied.

Photosensitizing properties of 6-methoxy-2-naphthylacetic acid, the major metabolite of the phototoxic non-steroidal anti-inflammatory and analgesic drug nabumetone.

The photobiological properties of 6-methoxy-2-naphthylacetic acid (6-MNAA) were studied using a variety of in vitro phototoxicity assays: photohemolysis, photoperoxidation of linoleic acid, photosensitized degradation of histidine and thymine and the Candida phototoxicity test. 6-MNAA was phototoxic in vitro. 6-MNAA reduced nitro blue tetrazolium (NBT) when irradiated with lambda > or = 300 nm in deoxygenated aqueous buffer solution (pH 7.4). NBT can be reduced by reaction with the excited state of 6-MNAA subject to interference with molecular oxygen. The photohemolysis rate was inhibited by the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO), sodium azide (NaN3) and reduced glutathione (GSH). Photoperoxidation of linoleic acid and photosensitized degradation of histidine and thymine were significantly inhibited by sodium azide and reduced glutathione. 6-MNAA was phototoxic to C. albicans, C. lipolytica and C. tropicalis. A mechanism involving singlet oxygen, radicals, and electron transfer reactions is suggested for the observed phototoxicity.

Microbial reduction in periodontal pockets under exposition of a medium power diode laser: an experimental study in rats.

BACKGROUND AND OBJECTIVE: This work evaluates the application of a 810 nm diode laser operating in the range of 400-1,200 mW for bacterial reduction at periodontal treatment. The aim of this study is to examine the immediate effect of the diode medium power laser in reducing the bacterial concentration at periodontal pockets induced in Wistar rats. STUDY DESIGN/MATERIALS AND METHODS: Two bacterial collections were performed on each animal. Microbiological samples were collected before and immediately after laser irradiation. In each group of laser power, eight animals were used, totaling 40 animals. RESULTS: The initial and the final bacterial count revealed that laser irradiation induces considerable bacterial elimination, especially for Prevotella sp, Streptococcus beta-hemolitico, Fusobacterium sp, Pseudomonas sp. CONCLUSIONS: Our results indicate that this laser can constitute an alternative device to traditional infrared systems for bacterial reduction, with some advantage when economical and practical standpoints are considered.