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Thesis (MSc (Physiological Sciences)--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Although muscle tissue demonstrates a remarkable capacity for regeneration following injury, this process is slow and often accompanied by the formation of scar tissue and a subsequent decrease in contractile capacity following regeneration. Treatment options are few and mostly supportive in nature. This regeneration process involves muscle stem cells (satellite cells) which ultimately give rise to the regenerated muscle. The contentious field of low level laser therapy (LLLT) has made remarkable claims in facilitating wound healing in soft tissue injuries of various types. Yet, the mechanism(s) invoked in these beneficial effects are poorly understood. We have investigated the effects of LLLT using a 638 nm laser on satellite cells in culture and in-vivo. Using an array of techniques we have measured, amongst other things, metabolic responses to laser irradiation, signaling pathways activated/altered and antioxidant status. In response to laser irradiation satellite cells in culture showed an increase in MTT values (a measure of metabolic activity) and a decrease in antioxidant status (measured using the ORAC assay). In addition laser irradiation also altered the expression and phosphorylation state of several signaling pathways, including Akt and STAT-3. Following on from this the effects of laser irradiation on satellite cells in-vivo was assessed in a rat model of contusion injury. No significant differences in satellite cell number was found following laser irradiation, changes were seen in tissue antioxidant status and blood antioxidant status (measured using the ORAC assay). In the course of this study several standard techniques were used to investigate the effects of laser irradiation on satellite cells both in-vitro and invivo. It has become apparent that several of these techniques have problems associated with them that possibly make them inappropriate for vi further use in studies involving laser irradiation. However the results indicate that laser therapy is induces satellite cell behavior and further study is warranted in this field. / AFRIKAANSE OPSOMMING: Alhoewel spierweefsel merkwaardige regenerasie kapasiteit vertoon ten opsigte van besering, is hierdie proses stadig en word soms vergesel met die vorming van letselweefsel asook ‘n gevolglike afname in kontaktiele kapasiteit na afloop van regenerasie. Behandelingsmoontlikhede is skaars en meesal ondersteunend van aard. Hierdie proses sluit spierstamselle (satelietselle), wat uiteindelik die ontstaan van die regenerasie van spier tot gevolg het, in. Die kontroversiële veld van lae vlak laserterapie (Engels: Low level laser therapy (LLLT)) het merkwaardige aansprake in die fasilitering met verskeie sagteweefsel wondgenesing. Nietemin, die meganisme(s) wat voordelige effekte induseer, word nog nie goed begryp nie. Ons het die effek van LLLT, deur gebruik te maak van ‘n 638 nm laser op kultuur in vitro satelietselle sowel in-vivo, ondersoek. Deur gebruik te maak van verskeie tegnieke is onder meer die metaboliese, sowel die seinstransduksie weë en antioksidantstatus na laserbestraling, gemeet. In reaksie op die laserbestraling het satelietselle (in kultuur) ‘n toename in MTT waardes getoon (‘n maatstaf van die metaboliese aktiwiteit) en ‘n afname in die antioksidantstatus (gemeet deur van die ORAC toets). Addisioneel het laserbestraling ook uitdrukking en fosforilering van verskeie proteïene betrokke in seintransduksieweë beïnvloed, insluitend Akt, STAT-3). Na afloop van hierdie effekte op satelietselle na laserbestraling, is daar gebruik gemaak van ‘n kneusbeseringsrotmodel om hierdie effekte in vivo te ondersoek. Geen betekenisvolle verskille in die aantal satelietselle na laserbestraling is opgemerk nie, maar veranderings is wel opgemerk in weefsel- en bloed-antioksidantstatus (gemeet deur van die ORAC toets gebruik te maak). Gedurende die verloop van die studie is van verskeie standaardtegnieke gebruik gemaak om die effekte van laserbestraling op beide satelietselle in vitro en in vivo te ondersoek. iv Dit het duidelik na vore gekom dat daar wel gepaardgaande probleme met van hierdie tegnieke voorgekom het, en dat van hierdie tegnieke nie gepas is vir ondersoek in laserbestralingsstudies nie. Nietemin, die resultate toon wel dat laserbehandeling. satelietselgedrag induseer wat verdere studie in hierdie veld noodsaak

Central America is a region regularly affected by natural disasters, with most of them having a hydro-meteorological origin. Therefore, the understanding of annual changes of precipitation upon the region is relevant for planning and mitigation of natural disasters. This thesis focuses on studying the precipitation variability at annual scales in Central America within the framework of the Swedish Centre for Natural Disaster Science. The aims of this thesis are: i) to establish the main climate variability sources during the boreal winter, spring and summer by using different statistical techniques, and ii) to study the connection of sea surface temperature anomalies of the neighbouring oceans with extreme precipitation events in the region. Composites analysis is used to establish the variability sources during winter. Canonical correlation analysis is employed to explore the connection between the SST anomalies and extreme rainfall events during May-June and August-October. In addition, a global circulation model is used to replicate the results found with canonical correlation analysis, but also to study the relationship between the Caribbean Sea surface temperature and the Caribbean low-level jet. The results show that during winter both El Niño Southern Oscillation and the Pacific Decadal Oscillation, are associated with changes of the sea level pressure near the North Atlantic Subtropical High and the Aleutian low. In addition, the El Niño Southern Oscillation signal is intensified (destroyed) when El Niño and the Pacific Decadal Oscillation have the same (opposite) sign. Sea surface temperature anomalies have been related to changes in both the amount and temporal distribution of rainfall. Precipitation anomalies during May-June are associated with sea surface temperature anomalies over the Tropical North Atlantic region. Whereas, precipitation anomalies during August-September-October are associated with the sea surface temperature anomalies contrast between the Pacific Ocean and the Tropical North Atlantic region. Model outputs show no association between sea surface temperature gradients and the Caribbean low-level jet intensification. Canonical correlation analysis shows potential for prediction of extreme precipitation events, however, forecast validation shows that socio-economic variables must be included for more comprehensive natural disaster assessments.

Låga moln definieras av att ha molnbasen från 0 till 2 km ovanför markytan. Molnbildande bygger på att den relativa fuktigheten stiger med höjden tills vattenångan i luften kondenseras. Prognosmodeller för moln bygger på grundläggande termodynamiska och fluiddynamiska ekvationer. Områden delas in i ett rutnät och ekvationerna löses med numeriska metoder. För jämförelse kan mätinstrument samt observationer användas, såsom ceilometrar, radar eller observatörer.  Resultat från fyra olika experiment med prognosmodeller för moln används i detta arbete, som är en litteraturstudie för att undersöka modellers förmåga att simulera låga moln. Olika platser, på global och lokal skala, undersöks. Makroskopiska parametrar såsom molnandel och molnfrekvens är i fokus.  WRF-modellen fungerar bäst med 12 km horisontell upplösning, med en viss överskattning av molnfrekvensen. Modellen CAM5 simulerar molnandel väl men vatteninnehåll och isinnehåll underskattas respektive överskattas. Säsongscykler av låga moln fångas väl av modellerna ECMWF, ARPEGE, RACMO och Met Office, med viss överskattning från samtliga modeller. GFS-modellen överskattar molnandelen långt från ekvatorn med upp mot 80% men underskattar nära ekvatorn med 10–20%. Överskattningar och underskattningar kan bero på faktorer såsom otillräcklig representation av mikrofysik eller möjligtvis felaktiga mätdata. Det denna studie visar är däremot att prognosmodeller på lokal skala kan ge bra simuleringar av makroskopiska parametrar av låga moln. / Cloud types are defined by the height of their bases. Low-level clouds have cloud base heights between 0 and 2 km. They are formed when the relative humidity in the air reaches 100 %, leading to the formation of cloud droplets. Forecast models simulate clouds by integrating thermodynamic and fluid dynamic equations using numerical methods. Instruments and observations, such as ceilometers or observers, are used to assess the accuracy of these simulations.  This study uses four previous works, where forecast models have been used to forecast clouds, to study the accuracy of low-level cloud forecasts. This is done on both local and global scales, focusing on macroscopic characteristics such as cloud fractions and frequencies. The results show that the WRF model works best with a horizontal resolution of 12 km, with slight overestimation of cloud frequencies. The climate model CAM5 simulates cloud fractions well, but liquid- and ice content deviate significantly from measurements. Seasonal cycles are generated well by ECMWF, ARPEGE, RACMO and Met Office Unified Model, with reoccurring overestimations by all models. The GFS model overestimates cloud fractions in higher latitudes by up to 80%, but underestimates near the equator by 10-20%.  Lacking representation of microphysics in the models, or faulty data, can be the causes for deviations in the models. However, this study has shown that forecast models can simulate macroscopic parameters of low-level clouds on a local scale well.

O objetivo deste estudo foi avaliar o efeito do laser de baixa intensidade na regeneração de defeitos ósseos críticos preenchidos com diferentes biomateriais. Foram utilizados 80 ratos machos adultos (Rattus norvegicus, albinus, Wistar) e um defeito de tamanho crítico (5 mm) foi criado na calvária de cada animal. Os animais foram divididos em 8 grupos experimentais (n=10): 1) Grupo C (Controle - coágulo sanguíneo), 2) Grupo LB (Laser de baixa intensidade - GaAlAs), 3) Grupo OA (osso autógeno), 4) Grupo OALB (osso autógeno + laser de baixa intensidade), 5) Grupo VB (vidro bioativo - Biogran), 6) Grupo VBLB (Biogran + laser de baixa intensidade), 7) Grupo BO (osso bovino - Bio-Oss®) e 8) Grupo BOLB (Bio-Oss® + laser de baixa intensidade). Os animais foram submetidos à eutanásia aos 30 dias pós-operatórios. Foram avaliadas as áreas de osso neoformado (AON) e de partículas remanescentes (APR). Os dados foram submetidos ao teste paramétrico ANOVA, seguido pelo teste de Tukey (p<0,05). O efeito fotobiomodulador do laser foi demonstrado no presente estudo uma vez que todos os grupos apresentaram maiores quantidades de AON quando comparados com o grupo C (9,96 ± 4,49%). Ao ser associado aos biomateriais, foi estatisticamente significativo somente quando relacionado ao Bio-Oss® (BOLB 48,57± 28,22). A menor área de APR foi encontrada nos grupos irradiados pelo laser, com diferença significativa somente no grupo BOLB (48,57± 28,22, p < 0,05). O laser de baixa intensidade demonstrou melhores resultados na regeneração óssea de defeitos de tamanho críticos, com maior taxa de AON, quando associado ao Bio-Oss®. / The purpose of this study was to evaluate the effect of low intensity laser on the regeneration of bone defects filled with different biomaterials. Eighty male rats (Rattus norvegicus, albinus, Wistar) were used and a critical size defect (5 mm) was created in the calvaria of each animal. The animals were divided into 8 experimental groups (n = 10): 1) Group C (Control - blood clot), 2) Group LB (Low intensity laser - GaAlAs), 3) Group OA (autogenous bone), 4) OALB group (autogenous bone + low intensity laser), 5) Group VB (bioactive glass - Biogran®), 6) VBLB Group (Biogran® + low intensity laser), 7) BO Group (bovine bone - Bio-Oss®) and 8) BOLB Group (Bio-Oss® + low intensity laser). The animals were submitted to euthanasia after 30 days postoperative. The areas of neoformed bone (AON) and of remaining particles (APR) were evaluated. The data were submitted to the ANOVA parametric test, followed by the Tukey test (p <0.05). The photobiomodulatory effect of the laser was demonstrated in the present study since all groups presented higher amounts of AON when compared to group C (9.96 ± 4.49%). When associated with biomaterials, it was statistically significant only when related to Bio Oss® (BOLB 48.57 ± 28.22, p < 0,05). The lowest APR area was found in the groups irradiated by the laser, with significant difference only in the BOLB group (48.57 ± 28.22). The low intensity laser showed better results in bone regeneration of critical size defects, with a higher AON rate, when associated with Bio-Oss®.

RESUMO Neste trabalho, a origem dos Jatos de Baixos Níveis (JBN) noturnos de Iperó (SP) e o seu papel na dispersão de poluentes no Estado de São Paulo são investigados. Para tanto são utilizados os dados coletados nas quatro campanhas de medidas em Iperó. Utilizou-se também um modelo numérico de mesoescala não-hidrostático TVM para simular a estrutura espacial 3-D do JBN em resposta as forçantes topográficas e associadas ocupação da superfície. Os resultados observacionais indicam que o JBN ocorre em Iperó com bastante freqüência nas noites de céu claro, com intensidade variando entre 8 e 10 m/s e localizado em torno de 350 m acima da superfície. Os JBNs em Iperó caracterizam-se por um cisalhamento direcional, com ventos de SE na superfície e de ENE na região de máximo. Ocorrem tanto no inverno como no verão, e afetam o ciclo diurno médio do vento observado nos primeiros 100 metros na região de Iperó. Os JBNs são responsáveis pelo máximo noturno (21:00 HL) existente no ciclo diurno médio do vento na região. Os resultados numéricos indicam que o JBN de Iperó é resultado da ação combinada de quatro fatores: (1) circulação anabática no setor paulista do vale do Rio Paraná; (2) oscilação inercial; (3) circulação catabática noturna e (4) brisa marítima. Estes quatro fatores combinados sustentam um JBN com intensidade de 5 a 10 m/s, localizados a uma altitude de 100 a 400 m acima da superfície, durante maior parte da noite. O JBN simulado numericamente encontra-se localizado no setor oeste da região de convergência da circulação anabática e da brisa marítima. Esta região de convergência em baixos níveis se forma durante o dia na parte mais elevada do Estado de São Paulo que acompanha da linha do litoral (Serra do Mar e da Cantareira). O efeito do JBN sobre o transporte de poluente foi investigado com um modelo Lagrangiano de dispersão de partículas. Verificou-se que o JBN aumenta a dispersão horizontal das partículas, transportando o poluente atmosférico emitido na superfície até 250 km da fonte. / ABSTRACT This work investigates the nocturnal Low-Level Jet (LLJ) in Iperó, Brazil, and its role in the pollutant dispersion on the State of São Paulo (SP). Data of four field campaigns in Iperó-SP was used in this investigation. A mesoscale and non-hydrostatic TVM model is also used to simulate the 3D structure of the LLJ, which is a dynamic response to topography and land use. The observational results indicate that the LLJ is frequently found during clear air nights, with a maximum between 8 and 10 m s–1, located around 350 m above surface. The LLJ in Iperó is characterized by a directional wind shear, with SE winds near surface and ENE near to the maximum. They occur during the winter and summer, and can modify the diurnal cycle of the mean wind in the first 100 m in the Iperó area. The LLJ are responsible by the nocturnal maximum (21:00 LT) in the mean wind in Iperó. The numerical results indicate the Iperó LLJ is a result of four factors: (1) anabatic circulation in São Paulo sector of the Paraná River Basin; (2) inertial oscillation; (3) nocturnal katabatic circulation and (4) sea breeze. These factors, together, sustain a LLJ with jet core intensity between 5 and 10 m/s, located between 100 and 400 m above surface during the major of nighttime period. The simulated LLJ numerically is found in the west sector in the convergence zone of the anabatic and sea breeze circulations. This convergence flow area appears during the daytime above the more elevated areas in the State of São Paulo, i.e., along mountains aligned parallel to coastline (Serra do Mar and Cantareira). The effects of the LLJ in a pollutant transport were investigated using a Lagrangian Particle Dispersion model coupled to the mesoscale model TVM. The results show that the LLJ increases the horizontal dispersion of the particles released near surface in Iperó and is able to transport the pollutant up to 250 km downwind the source.

INTRODUÇÃO: A Artrite aguda do joelho é o tipo mais comum de artrite, e sua prevalência aumenta em paralelo com o aumento da idade da população. Há muitas evidências de benefícios clínicos do laser para o tratamento da osteoartrite. No entanto, existem poucos estudos abordando os efeitos de 810 nm laser. Aqui nós iremos investigar os efeitos de Laser de Baixa Potencia (infra-vermelho, 810 nm). MATERIAL E MÉTODOS: Ratos Wistar machos (230 - 250g) foram anestesiados com halotano antes da injeção de pró-inflamatórios compostos. Carragenina e Kaolin, ambos a 3%, em solução diluída em soro Fisiológico, administrado intra-articular. Os grupos tratados receberam irradiação laser no local. Após 6 horas todos os animais foram anestesiados e mortos por deslocamento cervical para coleta de cavidade articular e lavado para celulares e análise bioquímica. O tecido articular foi analisado por PCR em tempo real análise, a fim de avaliar a expressão de COX-1 e COX-2. IL-1, TNF-alfa e IL-6 e a mieloperoxidase (MPO) também foi realizada. RESULTADOS E DISCUSSÃO: A terapia com laser de baixa potência foi capaz de inibir o número total de leucócitos, atividade de mieloperoxidase, o extravasamento vascular, IL-1b, TNF-a, IL-6 e Prostaglandina E2. / Introduction. Arthritis of the knee (AK) is the most common type of osteoarthritis, and its prevalence is rising in parallel with the increasing age of the population.. Here we investigate the effects of Low Level Laser Therapy (infra-red, 810 nm) in experimentally induced rat knee osteoarthritis. Methods. Male wistar rats (150 200g) were anaesthetized with halothane 1% prior the injection of pro-inflammatory compounds. Carrageenan and Kaolin (both 3%) administered intra-articular. After 6 hours all animals were killed by decaptation and articular cavity was washed and collected. Articular Tissue was carefully removed for edema and Real-time PCR analysis in order to evaluate COX-1 and COX-2 expression. Total and differential cell account, mieloperoxidase activity, IL-b, TNF-a, IL-6 was also analysed. Results. Low Level laser therapy was able to significantly inhibit the total number of leukocytes as well as the mieloperoxidase activity, polymorphonuclear cells at the inflammatory site, vascular extravasation, IL-1, TNF-alpha, IL-6 and prostaglandin E2. Conclusions. Low Level Laser Therapy operating in 810 nm markedly reduced inflammation in carrageenan, kaolin-induced knee osteoarthritis.

A cicatrização do tendão é um complexo processo que envolve uma variedade de moléculas reguladoras. Como exemplos temos os fatores de crescimento positivamente correlacionados com a expressão de genes responsáveis pela síntese da matriz extracelular, bem como os proteoglicanos que atuam como organizadores dos tecidos capazes de modular o crescimento e a maturação celular de tecidos especializados. No intuito de reparar o tendão com lesão existem várias opções de tratamento, mas nenhuma tem sido relatada como plenamente eficaz. Sendo assim, na busca de tratamentos regenerativos e não apenas reparativos, o objetivo deste trabalho foi investigar a influência do plasma rico em plaquetas (PRP) no processo de cicatrização do tendão flexor digital superficial de equinos, utilizando-se deste tratamento isoladamente ou associado ao laser terapêutico. Com essa finalidade, 26 membros torácicos de equinos foram distribuídos aleatoriamente em quatro grupos distintos: o grupo 1 (G1) foi composto por oito membros torácicos sadios provenientes de cadáveres frescos; no grupo 2 (G2) em seis membros foi induzida a tendinite, sem a realização de qualquer tipo de tratamento; no grupo 3 (G3) a tendinite também foi induzida em seis membros, os quais receberam o tratamento com o PRP; e no grupo 4 (G4) a tendinite foi induzida em seis membros torácicos que receberam o tratamento com o PRP associado ao laser terapêutico. Os animais foram avaliados clinicamente e ultrassonograficamente. Já as amostras do tecido tendíneo, obtidas por biópsia guiada por ultrassom, foram avaliadas por imunoistoquímica quanto a presença dos proteoglicanos: decorim, biglicam, fibromodulim e agrecam, Nessas amostras também foi realizada a análise da birrefringência do colágeno. Na avaliação clínica verificou-se que o grupo G4 foi o único que não mais apresentou sensibilidade à palpação no local da lesão ao término do experimento. Já na avaliação ultrassonográfica, os tendões dos membros torácicos dos grupos G3 e G4 que receberam os tratamento com PRP demonstraram melhora na ecogenicidade tanto do tendão como da lesão. Além disso, os tendões do grupo G4 apresentaram melhora no paralelismo das fibras de colágeno. Na avaliação imunoistoquímica os resultados demostraram que o biglicam, o fibromodulim e o agrecam tiveram sua expressão aumentada nas amostras do grupo G4 tratados com a associação PRP e laser quando comparados com as amostras do tendão hígido do grupo G1. Já no grupo G2 observou-se apenas o aumento da expressão de agrecam em relação ao G1. Na análise da birrefringência do colágeno o maior valor de retardo óptico (OR) foi apresentado também nas amostras do grupo tratado com a associação do PRP e laser (G4). Durante o processo de regeneração de um tendão lesado há uma tendência para o aumento dos valores de OR, o que representa uma melhora na organização do colágeno. Provavelmente, o laser foi capaz de produzir um aumento na síntese de colágeno e uma melhor agregação e alinhamento das fibras de colágeno. Assim, concluímos que o tratamento com PRP associado ao laser demonstrou melhora clínica, ultrassonográfica, de birrefringência e na expressão de proteoglicanos da matriz extracelular, o que não ocorreu quando utilizado isoladamente. / Tendon healing is a complex process involving a variety of regulatory molecules. Growth factors are a family of such molecules; and their presence is positively correlated with the expression of genes responsible for extracellular matrix synthesis. Proteoglycans more than extracellular matrix components are tissue organizers capable of modulating cell growth and maturation in specialized tissues. In order to repair the tendon injury there are several treatment options, but none has been reported as fully effective. In this scenario, regenerative approaches are currently preferred over reparative therapeutic procedures. Therefore, the aim of this study was to investigate the influence of platelet-rich plasma (PRP) in the healing of the equine superficial digital flexor tendon, using this treatment, alone or associated with the laser therapy. For this purpose, 26 equine forelimbs were randomly divided into four groups: group 1 (G1) consisted of eight healthy forelimbs from fresh cadavers; in group 2 (G2), tendinitis was induced in six forelimbs, without performing any type of treatment; in group 3 (G3), tendinitis was also induced in six forelimbs which received PRP treatment; and in group 4 (G4), tendinitis was induced in six forelimbs that received treatment with PRP associated with laser therapy. All animals were evaluated clinically and sonographically. Additionally, tendon tissue samples were obtained by ultrasound-guided biopsy, and assessed by immunohistochemistry to determine proteoglycans expression (decorin, biglycan, fibromodulin and aggrecan). These samples were further analyzed for collagen organization through birefringence. In the clinical evaluation, only G4 animals had absent painful response to direct digital palpation at the end of the experiment. During sonographic evaluation, it was observed that tendons from groups G3 and G4, that received the treatment with PRP, demonstrated improvement in both tendon and lesion echogenicity. Furthermore, tendons from the G4 group showed improvement in axial alignment of collagen fibers. The results showed an increase in biglycan, fibromodulin and aggrecan expression at immunohistochemical evaluation of G4 samples, when compared with healthy tendon samples (G1). In tendons from the G2 group only an increased aggrecam expression compared to G1 was observed. Though the analysis of the collagen birefringence, the highest value of optical retardation (OR) was also presented in the samples of the group treated with the combination of PRP and laser (G4). During the regeneration process of an injured tendon, there is a trend to increase OR values, which represents an improvement of the collagen organization. Probably, the laser was able to induce an increased synthesis and a better aggregation and alignment of collagen. So, we conclude that the animals treated with PRP associated with laser therapy improved clinically and sonographically. Moreover, this treatment improved the arrangement of collagen fibril and enhanced the proteoglycans expression in the extracellular matrix, what did not occur when PRP treatment was used alone.

O objetivo deste estudo foi investigar o efeito da Terapia Fotodinâmica antimicrobiana (TFDa) sobre o Enterococcus faecalis (E. faecalis), in vitro, utilizando a clorofila (CL) como agente fotossensibilizador (FS) e o diodo emissor de luz (LED) como fonte de luz. A cultura pura de E. faecalis foi ativada em caldo de BHI a 37oC por 24h. O cultivo do microrganismo foi centrifugado a 3000rpm por 15min, e o pellet re-suspenso em 0,85% de solução salina. As concentrações da bactéria foram ajustadas para 107UFC mL-1 (unidades formadoras de colônias por mililitro). Diferentes tipos de solventes para a CL foram testados: éter, álcool de cereais, Tween 80 e P-123. 100l do inóculo e o mesmo volume da solução teste foram inseridos em cada poço da placa de microtitulação. A mistura foi agitada e aguardou-se 1min. 25l da suspensão foi removida e diluições seriadas foram realizadas. Alíquotas de cada diluição foram espalhadas na superfície da placa, armazenadas em microaerofilia e incubadas na estufa por 24h a 37oC. O número de UFC foi contado em cada placa. Para o experimento da TFDa, os grupos foram divididos em: controle (G1); TBO 1min (G2); CL+Tween 1min (G3); CL+Tween 5min (G4); CL+P-123 1min (G5); CL+P-123 5min (G6); CL+Tween 1min + LED 1min (G7); CL+Tween 1min + LED 5min (G8); CL+Tween 5min + LED 1min (G9); CL+Tween 5min + LED 5min (G10); CL+P-123 1min + LED 1min (G11); CL+P-123 1min + LED 5min (G12); CL+P-123 5min + LED 1min (G13); CL+P-123 5min + LED 5min (G14); TBO 1min + LED 1min (G15); TBO 1min + LED 5min (G16); LED 1min (G17); LED 5min (G18).Um volume de 100l da suspensão bacteriana foi inserido em poços da placa e o mesmo volume da solução do FS foi adicionado. A CL foi solubilizada em soluções aquosas de Tween ou P-123. Cada poço foi agitado e o tempo de préirradiação foi de 1 ou 5min. O LED foi acionado durante 1 ou 5min. 25l da suspensão foi submetida a diluições seriadas e as alíquotas de cada diluição foram espalhadas na superfície da placa em Ágar BHI. As placas foram armazenadas e colocadas na estufa a 37oC por 24h. Os experimentos foram realizados em triplicata e as UFC em cada placa foram contadas. As UFC foram transformadas em valores de Log10 UFC para normalizar os dados para análise estatística. A média e o desvio padrão (DP) de cada experimento foram calculados. Os resultados mostraram que o Tween e o P-123 foram os solventes mais eficazes para diluição da CL. A TFDa com utilização da CL diluída em Tween ou P-123 com tempo de pré-irradiação de 5min e com a ação do LED por 5min causou uma pequena diminuição na contagem bacteriana. A CL diluída em Tween com tempo de 1min teve uma redução significante da contagem bacteriana. O TBO quando associado ao LED durante 1min provocou uma leve redução no número de UFC. A irradiação pelo LED durante 5min foi capaz de causar uma diminuição significativa da quantidade de UFC. / The aim of this study was to investigate the effect of Antimicrobial Photodynamic Therapy (aPDT) against Enterococcus faecalis (E. faecalis), in vitro, using chlorophyll (CL) as photosensitizer (FS) agent and light-emitting diode (LED) as light source. Pure culture of E. faecalis was cultivated in BHI broth at 37oC for 24h. The culture was centrifuged at 3000rpm for 15min, and the pellets were resuspended in 0.85% saline solution. The bacterial concentrations were adjusted to 107CFU mL-1 (colony forming units per milliliter). Different types of solvents for CL were tested: ether, grain alcohol, Tween 80 and P-123. 100l of inoculum and the same volume of the test solution were inserted into each well of the microtitre plate. The mixture was mixed and 1 min was awaited. 25l of the suspension was removed and serial dilutions were performed. Aliquots of each dilution were spread on the surface of the plates, stored in microaerophilic conditions and incubated for 24h at 37oC. The number CFU was counted in each plate. For aPDT experiment, the groups were divided into: control (G1); TBO 1min (G2); CL+Tween 1min (G3); CL+Tween 5min (G4); CL+P-123 1min (G5); CL+P-123 5min (G6); CL+Tween 1min + LED 1min (G7); CL+Tween 1min + LED 5min (G8); CL+Tween 5min + LED 1min (G9); CL+Tween 5min + LED 5min (G10); CL+P-123 1min + LED 1min (G11); CL+P-123 1min + LED 5min (G12); CL+P-123 5min + LED 1min (G13); CL+P-123 5min + LED 5min (G14); TBO 1min + LED 1min (G15); TBO 1min + LED 5min (G16); LED 1min (G17); LED 5min (G18). A volume of 100l of bacterial suspension was inserted into the well of microtitre plate and the same volume of FS was added. CL was solubilized in aqueous solution of Tween and P-123. Each well was mixed and preirradiation time was 1 or 5min. LED was irradiated during 1 or 5 min. 25l of suspension was subjected to serial dilutions and aliquots of each dilution were spread on the surface of agar BHI plates. The plates were stored and incubated at 37oC for 24h. Experiments were performed in triplicate and CFU in each plate were counted. The results showed that Tween and P-123 were the most effective solvents for CL dilution. aPDT with diluted CL in Tween or P-123 with pre-irradiation time of 5min and with LED irradiation for 5min caused a small decrease in bacterial count. CL diluted in Tween with 1min time showed a significant reduction in bacterial count. TBO when associated with LED irradiation of 1min caused a slight reduction on CFU number. LED irradiation during 5min caused a significant reduction in CFU count.