ROS-induced autophagy reduces B16F10 melanoma cell proliferative activity.

Cancer is a pathology characterized by increased cell progression and/or reduced programmed cell death. Melanoma shows a rapid increase in cell progression and its resistance to chemotherapy is associated with uncontrolled apoptosis and to mechanisms that increase the flow of the drug out of the cell. The objective of this study was to evaluate the effects of photodynamic therapy (PDT) on the cell proliferation and cellular alterations in B16F10 murine melanoma. For that, four experimental groups were evaluated: the control group; laser group (ʎ = 660 Î·m, 40 mW, 2.4 J/cm2); photosensitizer group (solution containing methylene blue and toluidine blue 1:1-12.5 µg/mL); PDT group. The incubation time was 30 min. Fluorescence microscopy assays were performed without fixation with the DAPI, monodansylcadaverine (MDC), and dihydroethidium (DHE) probes. Cell proliferation was also determined at 24-h time. The tests were performed in triplicate and the statistical test used was ANOVA with Tukey post-test. The results demonstrate that the plasma membrane of the cells of all the experimental groups remained intact, ROS production and autophagy significantly increased (p < 0.0005 and p < 0.0071, respectively) only in the PDT group. The cell proliferation essay showed a reduction of 74.2% on the PDT group in relation to the control group. The present study demonstrated that oxidative stress promoted by photodynamic therapy may induce autophagy and consequently reduce cell proliferation in B16F10 melanoma.

Histological evaluation of skin lesions induced by Leishmania braziliensis treated by PACT using Laser light and 1.9 dimethyl-methylene blue.

This study aimed to perform a histological evaluation in skin lesions caused by Leishmania braziliensis after PACT treatment using Laser associated with 1.9. dimethyl methylene blue BALB/c mouse ear infection model was used. A total of 40 animals were assigned into two groups considering time intervals at 5 and 10 weeks and subdivided into four subgroups: Control, Photosensitizer, Laser and PACT. Two therapeutic interventions were performed after the 5th week of infection at 48 h intervals. 1.9 Dimethyl methylene blue was used as a photosensitizer at the concentration of 7 ng/mL, with a non-invasive topical administration method associated with Laser (λ = 660 nm, 40 mW, 12 J/cm2). Sample collection occurred 5 or 10 weeks after therapeutic interventions. The main histological findings were observed in the laser and PACT groups at the 10-week evaluation. The Laser group showed reduced lymphoplasmacytic inflammation and histiocytes (p = 0.0079). The PACT group showed reductions in lymphoplasmacytic inflammation at 5 and 10 weeks, discrete reduction of histiocytes and a higher percentage of tissue remodeling. PACT with non-invasive topical administration of the photosensitizer was able to reduce lymphoplasmacytic inflammation and increase tissue remodeling in leishmaniosis skin lesions. This protocol may be easily used in humans and clinical trial shall be carried out to confirm the animal's findings.

Enhancement of photodynamic inactivation of planktonic cultures of Staphylococcus aureus by DMMB-AuNPs.

Photodynamic inactivation is a promising method for the treatment of infectious diseases. Nanotechnology through gold nanoparticles, as a tool to improve the delivery of photosensitizer is an attractive approach to enhance photodynamic inactivation of bacteria. Moreover, gold nanoparticles enchance the absorption of light due to their plasmon resonance. The aim of this study was to evaluate in vitro photodynamic inactivation effects of 1.9-Dimethyl-Methylene Blue (DMMB)-AuNPs associated with the red LED (λ630 ηm ± 20 ηm, 125 mW, 12 J / cm², 192 s) on S. aureus strain. Eight experimental groups were studied: Control, LED, AuNPs, AuNPs + LED, DMMB, DMMB + LED, DMMB + AuNPs, DMMB + AuNPs + LED. After incubation, the number of bacteria surviving each treatment was determined and then enumerated by viable counting (CFU / mL). The logarithm of CFU / mL (CFU/mL log10) was calculated. All experiments realized in triplicate. The statistical analyses included one-way ANOVA tests, Tukey's multiple comparisons and nonlinear regression, p values <0.05 were considered statistically significant. According to results, the photodynamic inactivation of S. aureus on groups DMMB + LED and DMMB-AuNPs + LED, showed a significant reduction of the microbial load (p < 0.0001) when compared to the Control group. The decimal reduction (RD) of these groups were 99.96 % (RD = 3) and 99.994 % (RD = 4) respectively. In conclusion, these findings demonstrated that photodynamic inactivation is enhanced by using DMMB-AuNPs on S. aureus.

aPDT using nanoconcentration of 1,9-dimethylmethylene blue associated to red light is efficacious in killing Enterococcus faecalis ATCC 29212 in vitro.

The Enterococcus faecalis is a microorganism that causes multiple forms of resistance to a wide range of drugs used clinically. aPDT is a technique in which a visible light activates photosensitizer (PS), resulting in generation of reactive oxygen species that kill bacteria unselectively via an oxidative burst. aPDT is an alternative to antibiotics with the advantage of not causing resistance. The search for an alternative treatment of infections caused by E. faecalis, without using antibiotics, is off great clinical importance. The aim of present investigation was to assess the efficacy of using 3.32 ηg/mL of 1,9-dimethylmethylene blue (DMMB) as photosensitizer associated with the use of either Laser (λ660 nm) or LED (λ632 ±â€¯2 nm) using different energy densities (6, 12 and 18 J/cm2) to kill E. faecalis in vitro. Under different experimental conditions, 14 study groups, in triplicate, were used to compare the efficacy of the aPDT carried out with either the laser or LED lights using different energy densities associated to DMMB. The most probable number method (MPN) was used for quantitative analysis. Photodynamic antimicrobial effectiveness was directly proportional to the energy density used, reaching at 18 J/cm2, 99.999998% reduction of the counts of E. faecalis using both light sources. The results of this study showed that the use of 3.32 ηg/mL of DMMB associated with the use 18 J/cm2 of LED light (λ632 ±â€¯2 nm) reduced >7-log counts of planktonic culture of E. faecalis.

Effects of photostimulation on the catabolic process of xenobiotics.

Light biotechnology is a promising tool for enhancing recalcitrant compounds biodegradation. Xenobiotics can cause a significant impact on the quality of the results achieved by sewage treatment systems due to their recalcitrance and toxicity. The optimization of bioremediation and industrial processes, aiming to increase efficiency and income is of great value. The aim of this study was to accelerate and optimize the hydrolysis of Remazol Brilliant Blue R by photo stimulating a thermophilic bacterial consortium. Three experimental groups were studied: control group; LED Group and Laser Group. The control group was exposed to the same conditions as the irradiated groups, except exposure to light. The samples were irradiated in Petri dishes with either a Laser device (λ660 nm, CW, θ = 0.04 cm2, 40 mW, 325 s, 13 J/cm2) or by a LED prototype (λ632 ±â€¯2 nm, CW, θ = 0.5 cm2, 145 mW, 44 s, 13 J/cm2). We found that, within 48-h, statistically significant differences were observed between the irradiated and the control groups in the production of RNA, proteins, as well as in the degradation of the RBBR. It is concluded that, both Laser and LED light irradiation caused increased cellular proliferation, protein production and metabolic activity, anticipating and increasing the catabolism of the RBBR. Being the economic viability a predominant aspect for industrial propose our results indicates that photo stimulation is a low-cost booster of bioprocesses.

Photobiological effect of Laser or LED light in a thermophilic microbial consortium.

Cellulose has a highly diversified architecture and its enzymatic complexes are studied for achieving an efficient conversion and a high level of efficiency in the deconstruction of cellulolytic biomass into sugars. The aim of this investigation was to evaluate the effect of Laser or LED light in the cellulolytic activity (CMCase) and on the proliferation of the thermophilic microbial consortium used on the degradation process of a lignocellulosic biomass of green coconut shell. The irradiation protocol consisted of six Laser irradiations (λ660 ηm, 40 mW, 270 s, 13 J/cm2) or LED (λ632 ±â€¯2 ηm, 145 mW, 44 s, 13 J/cm2) with 12- h time intervals in nutrient deprivation conditions. After irradiation, the consortium was inoculated into a lignocellulosic biomass (coconut fibers). Non- irradiated consortium was also inoculated and acted as control. Cell proliferation and endoglucanase activity were quantified during the experimental time. Experiments were carried out in triplicate. The results showed an increase of 250 % of thermo-cellulolytic microorganisms for the LED group and 200% for the Laser group when compared to the control. The enzymatic index (red Congo method), showed a statistically significant difference in the process of degradation of the lignocellulosic biomass between the Laser and LED groups compared to the control group [p < 0.0029; p < 0.029, respectively] 48-hs after the inoculation of the microorganisms. At the end of 72-h, this significant difference was maintained for both irradiated groups (p < 0.0212). Based upon the protocol used on the present study, it is possible to concluded that LED light enhanced cell proliferation of the thermophilic microbial consortium while the Laser light increase the enzymatic index of the lignocellulosic biomass of green coconut shell.

Effects of PACT using phenothiazine-derived drugs and red light on the macrophage x S. aureus interface.

The aim of this study was to evaluate the lethal potential of macrophages infected with Staphylococcus aureus after PACT (Photochemical Antimicrobial Chemotherapy) using phenothiazine derivatives (a solution containing 1:1 methylene blue and O toluidine blue) and laser (660 nm, 40 mW, 60 s, 12 J/cm2) or LED (632 ±â€¯2 nm, 145 mW, 40 s, 12 J/cm2). Six experimental groups were evaluated: Control Group (untreated); Photosensitizer group (phenothiazines - 12.5 µg/mL); Laser Group; LED Group; Laser PACT Group; and LED PACT Group. The pre-irradiation time used in this study was 5 min. Macrophages and bacteria were cultured in specific culture media and/or allowed interaction between the cell types. Subsequently, tests were carried out to evaluate microbial proliferation, ROS production by macrophages and survival capacity of S. aureus after phagocytosis. Fluorescence microscopy assays were performed with the H2DCFDA probe, after PACT, at the initial time (0 h), 4-h and 12-h. The tests were performed in triplicate and the statistical test used was ANOVA with Tukey post-test. After PACT, a statistically significant difference (p > 0.0001) was observed between the microbial growth of the control group and the PACTs groups. Laser PACT and LED PACT groups presented, respectively, reductions of 84.2% and 81.5% when compared to control and 53.3% and 46% when compared to the photosensitizer group. It is concluded that the therapeutic protocols presented in this study increased the phagocytic capacity, the response rate of the phagocytes and the consequent reduction of the numbers of S. aureus for both PACT protocols, however the increase in ROS production was only observed in the group irradiated with Laser light.