Low-Level Laser Therapy Activates NF-kB via Generation of Reactive Oxygen Species in Mouse Embryonic Fibroblasts

Background Despite over forty years of investigation on low-level light therapy (LLLT), the fundamental mechanisms underlying photobiomodulation at a cellular level remain unclear. Methodology/Principal Findings In this study, we isolated murine embryonic fibroblasts (MEF) from transgenic NF-kB luciferase reporter mice and studied their response to 810 nm laser radiation. Significant activation of NF-kB was observed at fluences higher than 0.003 J/cm2 and was confirmed by Western blot analysis. NF-kB was activated earlier (1 hour) by LLLT compared to conventional lipopolysaccharide treatment. We also observed that LLLT induced intracellular reactive oxygen species (ROS) production similar to mitochondrial inhibitors, such as antimycin A, rotenone and paraquat. Furthermore, we observed similar NF-kB activation with these mitochondrial inhibitors. These results, together with inhibition of laser induced NF-kB activation by antioxidants, suggests that ROS play an important role in the laser induced NF-kB signaling pathways. However, LLLT, unlike mitochondrial inhibitors, induced increased cellular ATP levels, which indicates that LLLT also upregulates mitochondrial respiration. Conclusion We conclude that LLLT not only enhances mitochondrial respiration, but also activates the redox-sensitive NFkB signaling via generation of ROS. Expression of anti-apoptosis and pro-survival genes responsive to NFkB could explain many clinical effects of LLLT.National Institutes of Health (U.S.) (grant R01AI050875)Center for Integration of Medicine and Innovative Technology (DAMD17-02-2-0006)United States. Dept. of Defense (CDMRP Program in TBI, W81XWH-09-1-0514)United States. Air Force Office of Scientific Research (FA9950-04-1-0079

Imaging of hydrogen peroxide in an HCCI engine using photofragmentation laser-induced fluorescence

Hydrogen peroxide (H2O2) is for the first time measured and imaged in two-dimensions in an HCCI engine using photofragmentation laser-induced fluorescence (PF-LIF). Qualitatively, the experimental data agree with simulations

Clinical evaluation of the effects of low-intensity laser (GaAlAs) on wound healing after gingivoplasty in humans Avaliação clínica dos efeitos do laser em baixa intensidade (GaAlAs) na cicatrização de gengivoplastia em humanos

Low-intensity laser therapy aims at pain suppression, edema reduction and acceleration of wound healing. The main goal of this study was to clinically evaluate the effects of Aluminum Gallium Arsenate laser - 670nm in wound healing after gingivoplasty in 11 patients. Surgery was performed in anterior superior and/or inferior regions. The right side of the patient (test group) received a laser energy density of 4J/cm&sup2;, in a 48-hour interval, during one week, totalizing four sessions. The irradiation was punctual in a contact mode in three points. The left side did not receive irradiation (control group). Clinical evaluation was performed by five specialists in periodontology through photography of the treated areas at post-surgical periods of 7, 15, 21,30,60 days. The observers pointed the best healed side. The Sign test was used for statistical analysis with a confidence level of 5% (P<0.05). The examiners found a better pattern of healing sometimes in the test and sometimes in the control group until 21 days after surgery. After this period there was no apparent difference between them. There was no statistical difference between the sides (p>0.05). These results have shown that low-intensity laser therapy did not accelerate oral mucosa healing after gingivoplasty.<br>A terapia com laser em baixa intensidade visa a biomodulação dos tecidos para se obter supressão da dor, redução do edema, e aceleração da cicatrização. O objetivo deste estudo foi avaliar, clinicamente, os efeitos do laser diodo de arseneto de gálio e alumínio (GaAlAs) - 670nm- na cicatrização de gengivoplastias em 11 pacientes. As cirurgias foram realizadas nas regiões anteriores superior e/ou inferior. O lado direito (teste) foi irradiado, na forma pontual, com 4J/cm&sup2; por ponto, em três locais diferentes. A aplicação do laser foi feita a cada 48h, durante uma semana, totalizando quatro sessões. O lado esquerdo (controle) não foi irradiado. A avaliação clínica foi feita por cinco periodontistas, através de fotografias dos períodos pós-operatórios de 7,15,21, 30 e 60 dias. Os examinadores apontaram o lado mais bem cicatrizado ou se ambos estavam iguais. Para análise estatística dos dados clínicos, foi utilizado o teste dos sinais com um nível de significância de 5% (p<0,05). Os resultados mostraram que havia preferência ora pelo lado teste, ora pelo lado controle até o período de 21 dias e nos períodos subseqüentes ambos os lados foram considerados iguais. A diferença entre os lados estudados não foi estatisticamente significante, sugerindo que o laser não acelerou a cicatrização da mucosa oral

Genotoxicity by rapeseed methyl ester and hydrogenated vegetable oil combustion exhaust products in lung epithelial (A549) cells

Biofuel is an attractive substitute for petrodiesel because of its lower environmental footprint. For instance, the polycyclic aromatic hydrocarbons (PAH) emission per fuel energy content is lower for rapeseed methyl ester (RME) than for petrodiesel. The present study assesses genotoxicity by extractable organic matter (EOM) of exhaust particles from combustion of petrodiesel, RME and hydrogenated vegetable oil (HVO) in lung epithelial (A549) cells. Genotoxicity was assessed as DNA strand breaks by the alkaline comet assay. EOM from combustion of petrodiesel and RME generated the same level of DNA strand breaks based on equal concentration of total PAH (i.e. net increases of 0.13 [95% confidence interval (CI): 0.002, 0.259 and 0.12 [95% CI: 0.01, 0.24] lesions per million base pairs, respectively). In comparison, the positive control (etoposide) generated much higher level of DNA strand breaks (i.e. 0.84, 95% CI: 0.72, 0.97) lesions per million base pairs). Relatively low concentrations of EOM from RME and HVO combustion particles (<116 ng/ml total PAH) did not cause DNA strand breaks in A549 cells, whereas benzo[a]pyrene and PAH-rich EOM from petrodiesel combusted using low oxygen inlet concentration were genotoxic. The genotoxicity was attributed to high molecular weight PAH isomers with 5-6 rings. In summary, the results show that EOM from combustion of petrodiesel and RME generate the same level of DNA strand breaks on equal total PAH basis. However, the genotoxic hazard of engine exhaust from on-road vehicles is lower for RME than petrodiesel because of lower PAH emission per fuel energy content