Orientador: Fábio Luiz Camargo Villela Berbert / Resumo: Objetivo: O objetivo desse estudo foi avaliar protocolos de agitação do EDTA aplicando dois diferentes tipos lasers de diodo de alta potência, comparando-os com os métodos de agitação convencional e com o ultrassom, quanto à extrusão apical, alteração de temperatura, resistência à fratura radicular e análise de pH na dentina radicular. Material e Métodos: Essa pesquisa experimental ex-vivo, utilizou 120 pré-molares inferiores, unirradiculados, com ráizes retas, com rizogênses completa e com tamanho radicular superior a 16mm, pré-selecionados por meio de radiografia digital. Suas coroas foram removidas, padronizando as raízes em 16 mm, seguido do preparo com a lima K#15 K#20 e o sistema reciproc R25, R40 e R50, 1 mm aquém do comprimento real do dente, com irrigação durante o preparo com NaOCl a 2,5%. Os espécimes foram distribuídos aleatoriamente em 6 grupos segundo protocolos de irrigação final: AD- água destilada (controle), CV- inundação com EDTA 17% e agitação com lima K #50, PUI- inundação com EDTA 17% agitado com ultrassom (Passive ultrasonic irrigation-PUI), PUI/CUI- inundação com EDTA 17% agitado com ultrassom (PUI) e irrigação com água destilada, agitada com ultrassom (Continuous ultrasonic irrigation-CUI), TL- inundação com EDTA 17% agitado com laser diodo Thera Lase Surgery, e GE- EDTA 17% agitado com laser diodo Gemini. Após irrigação final, todos os dentes foram irrigados com água destilada para remoção do EDTA. Resultados: Na avaliação da extrusão apical foi real... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Objective: The objective of this study was to evaluate EDTA agitation protocols by applying two different types of high-power diode lasers, comparing them with conventional agitation methods and with ultrasound, in relation to apical extrusion, temperature change, fracture resistance root and pH analysis in root dentin. Material and Methods: This ex-vivo experimental research used 120 lower premolars, uniradicular, with straight roots, with complete rhizogenesis and with root size greater than 16mm, pre-selected by means of digital radiography. Their crowns were removed, standardizing the roots by 16 mm, followed by preparation with the K # 15 K # 20 file and the reciproc system R25, R40 and R50, 1 mm below the actual length of the tooth, with irrigation during preparation with NaOCl to 2.5%. The specimens were randomly distributed into 6 groups according to final irrigation protocols: AD- distilled water (control), CV- flood with 17% EDTA and agitation with K # 50 file, PUI- flood with 17% EDTA agitated with ultrasound (Passive ultrasonic irrigation-PUI), PUI / CUI- flooding with 17% EDTA stirred with ultrasound (PUI) and irrigation with distilled water, stirred with ultrasound (Continuous ultrasonic irrigation-CUI), TL- flooding with 17% EDTA stirred with laser diode Thera Lase Surgery, and GE-EDTA 17% stirred with Gemini diode laser. After final irrigation, all teeth were irrigated with distilled water to remove EDTA. Results: In the evaluation of the apical extrusion, the... (Complete abstract click electronic access below) / Mestre

This thesis presents a study of lasing properties and optical amplification in semiconducting conjugated polymers and dendrimers. Configured as surface-emitting distributed feedback lasers, the effect of incorporating wavelength-scale microstructure on the output of the devices is examined along with the ability to create such structures using simplified fabrication processes such as soft lithography. Conjugated materials have received a great deal of interest due to their broad spectral absorption, emission, ability to exhibit gain and ease of processing from solution. As a result, they show great potential for a variety of applications such as photovoltaics, displays, amplifiers and lasers. To date however, there has only been one demonstration of a polymer optical amplifier. A broadband, solution based polymer amplifier is presented where the gain overlaps with the transmission window of polymer optical fibres. The effect of transitions that reduce the availability of gain in conjugated polymers is also examined by studying saturation of absorption in thin films. Producing wavelength scale microstructure is traditionally a slow, expensive technique. Here, solvent assisted micromoulding is used to pattern polymer films in less than two minutes. The effect of the variations in the pattern transfer on the laser characteristics is examined. The micromoulding technique is then applied to fabricating novel device types such as circular gratings and flexible plastic lasers. Encapsulation of the micromoulded laser is then shown to improve the lifetime of the device by over three orders of magnitude. The degradation effects witnessed during this extended operation are characterised quantitatively, an area of study where little data exists in the literature. A novel class of branched dendrimer materials whose properties can be independently tuned due to their modular architecture are configured as blue-emitting distributed feedback lasers. The ability to tune the emission wavelength by varying the film thickness is demonstrated. By changing the chemical groups contained within the molecule, further tuning of the emission can be obtained along with the demonstration of a highly efficient blue-emitting dendrimer laser. Chemosensing using dendrimer lasers is presented by demonstrating the incredibly sensitive response of the laser device to trace vapours of nitro-benzene compounds. The future application of which could be highly beneficial in the detection of explosives.

The work presented in this thesis is concerned with development of spectroscopic detection methods based on absorption spectroscopy using semiconductor lasers, with particular ref- erence to the field of medical diagnostics through breath analysis. The first part of this thesis deals with the design and testing of a prototype analyser for simultaneous monitoring of the exchange gases O₂ , CO₂ and H₂O in breath. The aim of this analyser is to provide information required to monitor respiration, with potential use in intensive care monitoring or during anaesthesia. The relatively high concentrations of these gases in breath and read- ily available diode laser sources make detection in the near-infrared (NIR) ideal. However, the relatively weakly absorbing A-band O₂ transitions at 760 nm require the application of a sensitive spectroscopic method, cavity enhanced absorption spectroscopy (CEAS). In contrast, CO₂ and H₂O are monitored using direct single pass absorption spectroscopy, with transitions arising from the 2ν₁ + ν₃ band at 2 μm and ν₁ + ν₃ band at 1.3 μm, respectively. It has been demonstrated that these gases can be detected simultaneously over a short pathlength (2.74 - 4 cm) in the respiratory flow by combining various spectroscopic methodologies and real-time data analysis. This analyser is shown to offer a viable alter- native for monitoring respiration, exhibiting absolute detection limits of changes of 0.26 % O₂ , 0.02 % CO₂ and 0.003 % H₂O with a 10 ms time resolution, which are comparable to current mass spectrometry based methods, but without their inherent delays. Following this, investigations into the detection of the main gas constituents in breath in the NIR employing noise-reduction modulation based spectroscopic techniques, namely wavelength and frequency modulation (WMS and FMS respectively) are also reported. The described WMS studies on water at 1.37 μm provide a demonstration of conventional WMS detection, as well as a “proof-of-principle” example of a relatively new approach to calibrating the non-absolute information obtained from a WMS absorption signal. Typically WMS spectra are calibrated using mixtures of known gas concentrations or an absolute direct absorption spectrum where possible. In this work however, a self-calibrating method, the phasor decomposition method (PDM), is employed and the returned concentration from this calibration is compared to direct absorption measurement. From this, the calculated concentration using the PDM is found to differ by 9 % from the concentration value obtained by direct absorption, providing an alternative method of calibration for when direct absorption measurements are not possible. The use of FMS in the NIR is also demonstrated as a potential alternative to CEAS for monitoring O₂ at 760 nm. FMS detection is performed on atmospherically broadened O₂ and a time-normalised α_min(t) of 2.45 ×10⁻⁶ cm⁻¹ s^1/2 is obtained, which is two orders of magnitude less sensitive than the value of α_min(t) = 2.35 ×10⁻⁸ cm⁻¹ s^1/2 obtained with CEAS. This combined with the experimental requirements of an FMS system, make its use for detection of O₂ a less practicable option compared to CEAS for real-time breath analysis. The latter work in this thesis involves a change in focus to detection of trace gases in breath in the mid-infrared (MIR). The move of spectroscopic detection to the MIR exploits the larger absorption cross-sections available in this region, and to achieve this, a relatively new form of semiconductor laser, the quantum cascade laser (QCL) is used. The design of a continuous wave QCL spectrometer at 8 μm and its operating characteristics are demon- strated and improvements in its performances are also discussed. This QCL system is then utilised to demonstrate the potential of monitoring species in breath, namely the narrow- band absorber methane and the broadband absorber acetone, taking into consideration the potential interference from other absorbing species in breath and the different spectroscopic characteristics exhibited by these molecules. Finally, the potential to further improve the sensitive detection of trace gases in breath in the MIR is also investigated with studies on the use of CEAS and multipass cells. In this work, the molecule of interest is the biomarker OCS, using transitions of the 2ν₂ band at 1031 cm⁻¹ , that are probed using a 10 μm QCL. The application of CEAS in the MIR is not as well developed as in the NIR, and the experimental consequences of using optical cavities at these wavelengths, where equipment tends to be more limited, are investigated and sensitivities discussed in the context of other literature. The experimental procedure of optimising a cavity for CEAS using the off-axis alignment method is also studied in detail, as well as the addition of WMS to further improve the signal quality. An effective absorption pathlength of ∼ 100 m was achieved in the cavity, with a bandwidth reduced α_min(BW) of 1.7 ×10⁻⁷ cm⁻¹ Hz^−1/2 using WMS CEAS achieved. With the poorer quality optics and limitations in equipment in the MIR for CEAS experiments, the use of a multipass cell, a 238 m Herriott cell, is also investigated as an alternative to the use of an optical cavity at 10 μm. Detection of OCS using direct absorption and WMS is demonstrated in the Herriott cell, achieving α_min(BW) = 2.03×10⁻⁸ cm⁻¹ Hz^−1/2 using WMS. This shows an improvement in sensitivity compared to WMS CEAS, and also shows the potential for future work on biomarker detection, as it approaches the ∼ ppb levels required for breath analysis.

Introdução: A Laserterapia de Baixa Intensidade (LTBI) é uma terapia que tem se mostrado eficiente na reparação tecidual em trabalhos com cultura celular e experimentos animais, mas existe uma escassez de trabalhos com cicatrização de incisões pós-cirúrgicas em humanos utilizando laser infravermelho GaAlAs de 830nm. O objetivo desse trabalho foi investigar a eficácia do laser infravermelho GaAlAs de 830nm no processo de cicatrização de incisão póscirúrgica de hérnia inguinal Métodos: 28 pacientes submetidos à cirurgia de hérnia-inguinal foram divididos randomicamente em grupo experimental (G1) e grupo controle (G2). O G1 recebeu tratamento com laser, sendo a primeira aplicação 24hs após a cirurgia e as demais dia sim dia não até um total de 4 aplicações. Ambos os grupos foram reavaliados após 6 meses por meio da Escala de cicatriz de Vancouver (ECV) e Escala visual analógica (EVA) e da espessura da cicatriz. As incisões foram irradiadas com laser diodo, =830 nm, 40 mW de potência de saída, 0,08cm² de diâmetro da ponteira de emissão, 26 segundos, 1,04J de energia por ponto e fluência de 13J/cm². Resultados: O G1 apresentou melhora significativa nas médias (p<0,05) da soma total da VSS 11 G1 2,14(±1,51) e G2 4,85(±1,87), na espessura G1 (0,11) e G2 (0,19) e na elasticidade da cicatriz G1 (0,14) e G2 (1,07). Conclusão: De acordo com os resultados obtidos nesse trabalho o tratamento com laser (830nm), usado na cicatrização de cirurgias de hérnia inguinal conseguiu melhorar a aparência e a qualidade da cicatriz seis meses após a incisão. / Background: Low Level Laser Therapy (LLLT) has been shown to be beneficial in the tissue repair process as shown in work done with tissue culture and animal experiments. However, there is a scarcity of work done with regard to post-surgical scarring of incisions in humans using infrared, 830nm, GaAlAs laser. The purpose of this study was to investigate the efficacy of an infrared, GaAlAs laser with a wavelength of 830nm in the post surgical scarring process after Inguinal Hernia Surgery. Method: 28 patients who underwent surgery for Inguinal Hernias were randomly divided into an Experimental Group (G1) and a Control Group (G2). The G1 received low level laser treatment (LLLT) with the first application being made 24 hours after surgery and then every other day for a total of 4 applications. Both Groups were re-evaluated after 6 months using the Vancouver Scar Scale (VSS), the Visual Analog Scale (VAS), and a measurement of scar thickness. The incisions were irradiated with an 830 nm diode laser operating with a continuous output power of 40 mW, spot size aperture of 0.08cm ², 26 seconds, an energy per point of 1.04J and energy density of 13J/cm ². Results: The G1 showed significantly better results; in the VSS totals (2.14±1.51) versus G2 (4.85±1.87), in the thickness measurements G1 (0.11 cm) versus G2 (0.19 cm), and in the pliability G1 (0.14) versus G2 (1.07). Conclusion: According to the results of this work LLLT (830nm) of Inguinal Hernia Scars resulted in better appearance and scar quality six months after surgery.

Introdução: A Laserterapia de Baixa Intensidade (LTBI) é uma terapia que tem se mostrado eficiente na reparação tecidual em trabalhos com cultura celular e experimentos animais, mas existe uma escassez de trabalhos com cicatrização de incisões pós-cirúrgicas em humanos utilizando laser infravermelho GaAlAs de 830nm. O objetivo desse trabalho foi investigar a eficácia do laser infravermelho GaAlAs de 830nm no processo de cicatrização de incisão póscirúrgica de hérnia inguinal Métodos: 28 pacientes submetidos à cirurgia de hérnia-inguinal foram divididos randomicamente em grupo experimental (G1) e grupo controle (G2). O G1 recebeu tratamento com laser, sendo a primeira aplicação 24hs após a cirurgia e as demais dia sim dia não até um total de 4 aplicações. Ambos os grupos foram reavaliados após 6 meses por meio da Escala de cicatriz de Vancouver (ECV) e Escala visual analógica (EVA) e da espessura da cicatriz. As incisões foram irradiadas com laser diodo, =830 nm, 40 mW de potência de saída, 0,08cm² de diâmetro da ponteira de emissão, 26 segundos, 1,04J de energia por ponto e fluência de 13J/cm². Resultados: O G1 apresentou melhora significativa nas médias (p<0,05) da soma total da VSS 11 G1 2,14(±1,51) e G2 4,85(±1,87), na espessura G1 (0,11) e G2 (0,19) e na elasticidade da cicatriz G1 (0,14) e G2 (1,07). Conclusão: De acordo com os resultados obtidos nesse trabalho o tratamento com laser (830nm), usado na cicatrização de cirurgias de hérnia inguinal conseguiu melhorar a aparência e a qualidade da cicatriz seis meses após a incisão. / Background: Low Level Laser Therapy (LLLT) has been shown to be beneficial in the tissue repair process as shown in work done with tissue culture and animal experiments. However, there is a scarcity of work done with regard to post-surgical scarring of incisions in humans using infrared, 830nm, GaAlAs laser. The purpose of this study was to investigate the efficacy of an infrared, GaAlAs laser with a wavelength of 830nm in the post surgical scarring process after Inguinal Hernia Surgery. Method: 28 patients who underwent surgery for Inguinal Hernias were randomly divided into an Experimental Group (G1) and a Control Group (G2). The G1 received low level laser treatment (LLLT) with the first application being made 24 hours after surgery and then every other day for a total of 4 applications. Both Groups were re-evaluated after 6 months using the Vancouver Scar Scale (VSS), the Visual Analog Scale (VAS), and a measurement of scar thickness. The incisions were irradiated with an 830 nm diode laser operating with a continuous output power of 40 mW, spot size aperture of 0.08cm ², 26 seconds, an energy per point of 1.04J and energy density of 13J/cm ². Results: The G1 showed significantly better results; in the VSS totals (2.14±1.51) versus G2 (4.85±1.87), in the thickness measurements G1 (0.11 cm) versus G2 (0.19 cm), and in the pliability G1 (0.14) versus G2 (1.07). Conclusion: According to the results of this work LLLT (830nm) of Inguinal Hernia Scars resulted in better appearance and scar quality six months after surgery.

Made available in DSpace on 2015-07-22T20:50:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-29 / Objetivo: Comparar a fotocoagulação focal e em grade de acordo com o protocolo do Early Treatment Diabetic Retinopathy Study modificado (mETDRS) utilizando fotocoagulação com laser diodo 810nm sublimiar em micropulsos e densidade normal (FSM-DN) ou aumentada (FSM-DA) no tratamento do edema macular diabético (EMD). Métodos: Foi conduzido um estudo randomizado, controlado, prospectivo, duplo mascarado com pacientes não tratados com EMD e melhor acuidade visual corrigida (MAVC), pior que 20/40 e melhor que 20/400. Pacientes foram aleatorizados para receber fotocoagulação de acordo com o protocolo mETDRS (42 pacientes), FSM-DN (39 pacientes) ou FSM-DA (42 pacientes). Imediatamente antes do tratamento, 3, 6, bem como 12 meses após ele, todos os pacientes foram submetidos a exame oftalmológico, MAVC, retinografia colorida, angiografia fluorescente e tomografia de coerência óptica (OCT). Efeitos adversos nas diferentes técnicas de fotocoagulação foram observados durante o acompanhamento do estudo. Resultados: Durante o acompanhamento, todos os grupos apresentaram redução da espessura macular central, com diminuição no grupo FSM-DA de 93μm em três meses, 117μm em seis meses e 144μm em nove meses, comparado à redução de 67, 94 e 112μm em três, seis e nove meses respectivamente, no grupo mETDRS. Já o grupo FSM-DN apresentou redução de 20μm em três e seis meses e 34μm em nove meses, significativamente inferior aos grupos FSM-DA e mETDRS. Em relação à acuidade visual, houve melhora da MAVC gradual em três, seis e nove meses nos grupos FSM-DA e mETDRS sem diferenças estatisticamente significativas entre estes grupos, porém ambos superiores ao grupo FSM-DN, que não apresentou mudança na acuidade visual nesses períodos. Em doze meses, o grupo FSM-DA teve o melhor resultado em termos de MAVC (0,25 logMAR), seguido do grupo mETDRS (0,08 logMAR), enquanto o grupo FSM-DN não apresentou melhora significativa na MAVC (0,03 logMAR) (p<0,001). Todos os grupos apresentaram redução estatisticamente significativa da espessura macular central no OCT (p<0,001). O grupo FSM-DA demonstrou a maior redução (154μm), porém não foi estatisticamente significativa em relação ao grupo mETDRS (126μm; p=0,75). Não foram observados efeitos adversos graves nas diferentes formas de tratamento. Conclusão: Em um ano, a resposta clínica do grupo FSM-DA foi superior aos grupos mETDRS e FSM-DN, baseada na medida de espessura central da mácula e acuidade visual. Estes dados sugerem que a técnica de FSM-DA pode ser utilizada como conduta preferível para o tratamento de EMD, porém estudos clínicos multicêntricos são necessários para confirmar estes resultados. / Purpose: To compare modified Early Treatment Diabetic Retinopathy Study (ETDRS) focal/grid laser photocoagulation with normal-density (ND-SDM) or high-density (HD-SDM) subthreshold diode-laser micropulse photocoagulation for the treatment diabetic macular edema (DME). Methods: We conducted a prospective, randomized, controlled, double-masked clinical trial with patients with previously untreated DME and best corrected visual acuity (BCVA) worse than 20/40 and better than 20/400. Patients were randomized to receive either modified ETDRS focal / grid photocoagulation (42 patients), ND-SDM (39 patients) or HD-SDM (42 patients). Before treatment and 3, 6 and 12 months after treatment, all patients underwent ophthalmic examinations, BCVA, color fundus photography, fluorescein angiography and optical coherence tomography (OCT). Results: At 12 months, the HD-SDM group had the best improvement in BCVA (0.25 logMAR), followed by the modified ETDRS group (0.08 logMAR), while no improvements were seen in the ND-SDM group (0.03 logMAR). All groups showed statistically significant progressive reduction of CMT throughout the study (p<0.001). The HD-SDM group exhibited the greatest CMT reduction (154 μm), which was not significantly different from that of the modified ETDRS group (126 μm; p=0.75). Conclusions: At 1 year, the clinical performance of HD-SDM was superior to that of the modified ETDRS photocoagulation technique based on the anatomic and functional measures of improvement used in this investigation. A rationale for this treatment modality as a preferable approach is suggested, and the precise role of sub-threshold micropulse laser treatment may become more defined as experience grows, guided by optimized treatment guidelines and more comprehensive trials. / TEDE / BV UNIFESP: Teses e dissertações

A terapia laser de baixa intensidade (LLLT) é capaz de modular a resposta inflamatória em vários modelos experimentais, reduzindo o infiltrado de células do sistema imune e a secreção de mediadores químicos. Estudos prévios sugerem sua utilidade também no tratamento da lesão pulmonar aguda (LPA), condição caracterizada por intensa reação inflamatória em vias aéreas distais. Assim, considerando os efeitos anti-inflamatórios do laser e a fisiopatologia da LPA, formulamos a hipótese de que a LLLT 660 nm, 10 J/cm2, poderia modular o processo inflamatório nessa patologia favorecendo a transição inflamação-reparo. Foram utilizados camundongos C57BL distribuídos aleatoriamente em 4 grupos: PBS- instilado com PBS intratraqueal; PBS+LLLT- irradiado com LLLT 6 horas após instilação intratraqueal de PBS; LPS- instilado com LPS (5 mg/kg); LPS+LLLT- irradiado com LLLT 6 horas após instilação intratraqueal de LPS. Observou-se que a instilação de LPS intratraqueal levou a um aumento do número de células inflamatórias tanto na região peribronquiolar quanto no lavado broncoalveolar (LBA), detectado na histologia pulmonar e pela expressão de F4/80. Houve também aumento da transcrição e secreção de citocinas (TNF-alfa, IL-1beta, IL-6, IL-10) e quimiocinas (MCP-1) (detectadas por PCR quantitativo e ELISA). A aplicação de LLLT 6 horas após a instilação de LPS causou uma significativa diminuição tanto no influxo de células inflamatórias quanto na secreção de mediadores. Em seguida, foram caracterizadas as populações de macrófagos presentes no tecido pulmonar e observou-se nos animais do grupo LPS+LLLT, comparados ao grupo LPS, uma diminuição na expressão de mRNA de HIF-1alfa e aumento para arginase 1, sugerindo um predomínio da população de macrófagos M2. Esse efeito da LLLT foi também testado em populações de macrófagos peritoneais estimulados com LPS em cultura, porém, embora houvesse diminuição da produção de citocinas e quimiocinas, não foram observadas diferenças nos marcadores de polarização dessas células / A low-level laser therapy (LLLT) is able to modulate the inflammatory response in several experimental models, reducing the infiltration of immune system cells and the secretion of chemical mediators. There are some previous studies suggesting also useful in the treatment of acute lung injury (ALI), a condition characterized by an intense inflammatory reaction in the distal airways. Considering the anti-inflammatory effects of laser and the pathophysiology of ALI, we hypothesized that LLLT 660 nm, 10 J/cm2, could modulate the inflammatory process in this disease favoring the transition between inflammation and repair. C57BL mice were divided into four groups: PBS - intratracheal instillation of PBS; PBS+LLLT - irradiated with LLLT 6 hours after intratracheal instillation of PBS; LPS - intratracheal instillation of LPS (5 mg/kg); LPS+LLLT - irradiated with LLLT 6 hours after intratracheal instillation of LPS. Animals were sacrificed 24 hours after injury. Intratracheal LPS inoculation induced a marked increase in the number of inflammatory cells in perivascular and alveolar spaces (detected by lung histology and in bronchoalveolar lavage), and F4/80 expression (macrophage marker). There was also an increase in the expression and secretion of cytokines (TNF-alfa, IL-1beta, IL-6, IL-10) and chemokine (MCP-1) detected by ELISA and quantitative PCR. The LLLT application 6 hours after LPS induced a significant decrease in both of the inflammatory cells influx and mediators secretion. Then, we characterized the macrophages populations in lung tissue and we observed that in the LPS+LLLT group the expression of HIF-1alfa mRNA was reduced while arginase 1 was increased, which suggested that the M2 macrophages were predominant. The LLLT effect was also tested on peritoneal macrophage population in culture stimulated with LPS and there was decreased of cytokines and chemokine production, however any difference in polarization markers was found

A terapia laser de baixa intensidade (LLLT) é capaz de modular a resposta inflamatória em vários modelos experimentais, reduzindo o infiltrado de células do sistema imune e a secreção de mediadores químicos. Estudos prévios sugerem sua utilidade também no tratamento da lesão pulmonar aguda (LPA), condição caracterizada por intensa reação inflamatória em vias aéreas distais. Assim, considerando os efeitos anti-inflamatórios do laser e a fisiopatologia da LPA, formulamos a hipótese de que a LLLT 660 nm, 10 J/cm2, poderia modular o processo inflamatório nessa patologia favorecendo a transição inflamação-reparo. Foram utilizados camundongos C57BL distribuídos aleatoriamente em 4 grupos: PBS- instilado com PBS intratraqueal; PBS+LLLT- irradiado com LLLT 6 horas após instilação intratraqueal de PBS; LPS- instilado com LPS (5 mg/kg); LPS+LLLT- irradiado com LLLT 6 horas após instilação intratraqueal de LPS. Observou-se que a instilação de LPS intratraqueal levou a um aumento do número de células inflamatórias tanto na região peribronquiolar quanto no lavado broncoalveolar (LBA), detectado na histologia pulmonar e pela expressão de F4/80. Houve também aumento da transcrição e secreção de citocinas (TNF-alfa, IL-1beta, IL-6, IL-10) e quimiocinas (MCP-1) (detectadas por PCR quantitativo e ELISA). A aplicação de LLLT 6 horas após a instilação de LPS causou uma significativa diminuição tanto no influxo de células inflamatórias quanto na secreção de mediadores. Em seguida, foram caracterizadas as populações de macrófagos presentes no tecido pulmonar e observou-se nos animais do grupo LPS+LLLT, comparados ao grupo LPS, uma diminuição na expressão de mRNA de HIF-1alfa e aumento para arginase 1, sugerindo um predomínio da população de macrófagos M2. Esse efeito da LLLT foi também testado em populações de macrófagos peritoneais estimulados com LPS em cultura, porém, embora houvesse diminuição da produção de citocinas e quimiocinas, não foram observadas diferenças nos marcadores de polarização dessas células / A low-level laser therapy (LLLT) is able to modulate the inflammatory response in several experimental models, reducing the infiltration of immune system cells and the secretion of chemical mediators. There are some previous studies suggesting also useful in the treatment of acute lung injury (ALI), a condition characterized by an intense inflammatory reaction in the distal airways. Considering the anti-inflammatory effects of laser and the pathophysiology of ALI, we hypothesized that LLLT 660 nm, 10 J/cm2, could modulate the inflammatory process in this disease favoring the transition between inflammation and repair. C57BL mice were divided into four groups: PBS - intratracheal instillation of PBS; PBS+LLLT - irradiated with LLLT 6 hours after intratracheal instillation of PBS; LPS - intratracheal instillation of LPS (5 mg/kg); LPS+LLLT - irradiated with LLLT 6 hours after intratracheal instillation of LPS. Animals were sacrificed 24 hours after injury. Intratracheal LPS inoculation induced a marked increase in the number of inflammatory cells in perivascular and alveolar spaces (detected by lung histology and in bronchoalveolar lavage), and F4/80 expression (macrophage marker). There was also an increase in the expression and secretion of cytokines (TNF-alfa, IL-1beta, IL-6, IL-10) and chemokine (MCP-1) detected by ELISA and quantitative PCR. The LLLT application 6 hours after LPS induced a significant decrease in both of the inflammatory cells influx and mediators secretion. Then, we characterized the macrophages populations in lung tissue and we observed that in the LPS+LLLT group the expression of HIF-1alfa mRNA was reduced while arginase 1 was increased, which suggested that the M2 macrophages were predominant. The LLLT effect was also tested on peritoneal macrophage population in culture stimulated with LPS and there was decreased of cytokines and chemokine production, however any difference in polarization markers was found