Photodynamic inactivation of Staphylococcus aureus and Escherichia coli biofilms by malachite green and phenothiazine dyes: An in vitro study

Objectives: The organization of biofilms in the oral cavity gives them added resistance to antimicrobial agents. The action of phenothiazinic photosensitizers on oral biofilms has already been reported. However, the action of the malachite green photosensitizer upon biofilm-organized microorganisms has not been described. The objective of the present work was to compare the action of malachite green with the phenothiazinic photosensitizers (methylene blue and toluidine blue) on Staphylococcus aureus and Escherichia coli biofilms.Methods: The biofilms were grown on sample pieces of acrylic resin and subjected to photodynamic therapy using a 660-nm diode laser and photosensitizer concentrations ranging from 37.5 to 3000 mu M. After photodynamic therapy, cells from the biofilms were dispersed in a homogenizer and cultured in Brain Heart Infusion broth for quantification of colony-forming units per experimental protocol. For each tested microorganism, two control groups were maintained: one exposed to the laser radiation without the photosensitizer (L+PS-) and other treated with the photosensitizer without exposure to the red laser light (L-PS+). The results were subjected to descriptive statistical analysis.Results: The best results for S. aureus and E. coli biofilms were obtained with photosensitizer concentrations of approximately 300 mu M methylene blue, with microbial reductions of 0.8-1.0 log(10); 150 mu M toluidine blue, with microbial reductions of 0.9-1.0 log(10); and 3000 mu M malachite green, with microbial reductions of 1.6-4.0 log(10).Conclusion: Greater microbial reduction was achieved with the malachite green photosensitizer when used at higher concentrations than those employed for the phenothiazinic dyes. (C) 2011 Elsevier Ltd. All rights reserved.

Evaluation of two morphometric methods of bone loss percentages caused by periodontitis in rats in different locations

Objective: The present study evaluated morphometrically bone loss percentages in experimental periodontitis in rats, comparing different locations (lingual mandible, palatal maxilla and buccal maxilla) and two evaluation methods (distance and area methods). Material and Methods: Ligatures were placed around the maxillary right second molar and around the mandibular right first molar in 14 female Wistar rats. The contralateral molars served as intragroup control. After 4 weeks, the rats were sacrificed and their mandible and maxilla were removed. The specimens were dissected and stained with methylene blue dye. Bone loss was evaluated by two different methods on the surfaces of the defleshed jaw. In the first method, the distance from the cementoenamel junction (CEJ) to the alveolar bone crest was measured in the roots of teeth associated with ligature. In the second method, the area of bone loss was determined using the alveolar tissue bone, CEJ and the proximal region of roots associated with the ligature as reference. The data were converted to bone loss percentages caused by ligature: (ligated - unligated) x 100/ligated. Results: When comparing the distance and area methods, no statistically significant difference was observed (p>0.05). Both methodologies indicated that the maxilla presented greater bone loss than the mandible and it was more accentuated on the buccal side than on the palatal side (p<0.05). Conclusions: The findings of this study show that both the area and the distance methods can be used to evaluate bone loss caused by ligature placement in rats, and suggest applying the morphometric methodology to the maxilla on the buccal side.

Effects of Nd : YAG and Er : YAG lasers on the sealing of root canal fillings

Objective: the ability of the laser irradiation to promote the cleaning and disinfection of the radicular canal system has become this type of treatment in a viable and real alternative in endodontics. The purpose of this study was to evaluate the apical marginal sealing of root canal fillings after the irradiation with the laser of Nd:YAG or of Er:YAG. Materials and Methods: Forty-two human, extracted single-rooted teeth had their crowns sectioned and the root canals prepared with a no. 70 K-file. Then, they were dried and divided into three groups according to canal wall treatment: group 1: the canals were filled with EDTA for 3 min, followed by irrigation with 1% sodium hypochlorite solution; group 2: the canal walls were irradiated with Nd:YAG laser; and group 3: the canal walls were irradiated with Er:YAG laser. Afterwards, the root canals were obturated by the lateral condensation technique. The roots were externally waterproof, except in the apical foramen and immerged in 2% methylene blue aqueous solution during 48 hours. Results: the results showed that the largest infiltrations happened in the group 3-Er:YAG (7.3 mm), proceeded by the group 1-EDTA (1.6 mm) and by the group 2-Nd:YAG (0.6 mm). The group Er:YAG differed statistically of the others (p < 0.05). Conclusion: It was concluded that the Er:YAG laser intracanal irradiation previously to the root canal filling must be used with caution until future research is define the best parameters for it's use.

Marginal leakage in Class V cavities pretreated with different laser energy densities

The purpose of the present study was to evaluate in vitro the degree of marginal leakage in Class V cavities involving the cementoenamel junction. Cavities were 4 rum wide and 2 mm deep. The specimens received dentin pretreatment (37% phosphoric acid) followed by the Single Bond (3M) adhesive system application. The 40 specimens were then divided into four groups: Group I (control); Group 2 (Nd:YAG laser at 120 mJ/pulse, frequency of 10 Hz, power of 1.2 W); Group 3 (Nd:YAG laser at 140 mJ/pulse, frequency of 10 Hz, power of 1.4 W); Group 4 (Nd:YAG laser at 160 mJ/pulse, frequency of 10 Hz, power of 1.6 W). The cavities were restored with Z100 composite resin (3M) and light cured at 300-600 mW/cm(2) light intensity. Specimens were thermocycled to 500 cycles from 2-50 degrees C. After that, they were dried and sealed with nail varnish, respecting 1 mm around the restorations, and immersed in 0.5% methylene blue solution for 4 h. After this period, the teeth were rinsed, dried, sectioned, and analyzed in a stereoscopic loupe. The highest leakage scores were considered for each specimen. The results were statistically analyzed by the analysis of variance (ANOVA) Kruskal-Wallis test to the 5% level. For both the enamel and cementum, there was a decrease in marginal leakage with the application of laser energy; no significant differences were observed for Groups 2, 3, and 4. The results also showed a smaller tendency to marginal leakage on the cementum than on the enamel.

Cimentos endodônticos - selamento marginal apical imediato e após armazenamento de seis meses

Este trabalho avaliou o selamento marginal apical de canais radiculares obturados com os cimentos endodônticos Sealapex, Apexit, Sealer 26 e Ketac Endo. Utilizaram-se 136 raízes, cujos canais radiculares, após o preparo biomecânico, foram obturados pela técnica da condensação lateral ativa com os cimentos em estudo. Metade das amostras, imediatamente após as obturações, foram imersas na solução de azul de metileno a 2% e a outra metade após 6 meses de armazenamento em plasma sangüíneo humano. Observou-se que os cimentos Sealapex e Sealer 26 apresentaram infiltrações médias estatisticamente iguais entre si e menores que as observadas para os demais cimentos (p < 0,05). Amostras imersas no corante imediatamente após a obturação dos canais apresentaram infiltração média menor (0,829 mm) do que aquelas mantidas por 6 meses em plasma sangüíneo humano (1,275 mm). Estas diferenças foram estatisticamente significantes (p < 0,05).

Nb-containing hematites Fe2-xNbxO3: The role of Nb5+ on the reactivity in presence of the H2O2 or ultraviolet light

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

New materials based on modified synthetic Nb2O5 as photocatalyst for oxidation of organic contaminants

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento de metodologia simplificada para análise de hexametilenotetramina (hmt) em medicamentos contendo corantes em sua formulação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do processamento UAT (Ultra Alta Temperatura) sobre as características físico-químicas do leite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Apical seal of root canals with gutta-percha points with calcium hydroxide

Foi propósito deste trabalho observar se o uso de cones de guta-percha contendo Ca(OH)2, promove melhora no selamento marginal apical e, também, se apenas o cone principal contendo essa droga produz esse efeito. Assim, dentes humanos extraídos foram preparados biomecânicamente e obturados pela técnica da condensação lateral com OZE e cones de guta-percha contendo ou não Ca(OH)2. Após imersão dos espécimes em azul de metileno a 2%, em ambiente com vácuo, observou-se diferença estatisticamente significante entre os espécimes obturados com cones contendo Ca(OH)2, comparativamente aos casos obturados com cones de guta percha comuns (p=0.01). Os resultados obtidos permitiram concluir que esses cones tornam as obturações mais herméticas e que esse efeito também pode ser obtido com o emprego do cone principal da mesma fórmula, aliado a cones acessórios comuns (p=0.05).

Linfadenectomia laparoscópica em cadela com neoplasia mamária

A linfadenectomia laparoscópica é realizada de forma rotineira na medicina, contudo é pouco utilizada na veterinária. Neste relato, um canino fêmea apresentando tumores na cadeia mamária esquerda (M4 e M5), foi submetido à aplicação intradérmica do azul de metileno estéril, ao redor do maior tumor (M5), buscando-se demarcação dos vasos linfáticos e linfonodos regionais. Após 15 minutos, iniciou-se a linfadenectomia abdominal videolaparoscópica na região inguinal esquerda, seguida da ovário-histerectomia (OVH) lapararoscópica com três portais. Realizou-se ainda mastectomia total unilateral esquerda. Pela histologia, obtiveram-se dois linfonodos abdominais livres de células tumorais. A paciente não apresentou recidiva em 60 dias.

Acidez total titulável, pH e tempo de redução do azul de metileno no fluido ruminal de caprinos mantidos em pastagens artificiais, exclusiva de gramíneas, ou em caatinga

O objetivo deste trabalho foi o de determinar a concentração hidrogeniônica (pH), acidez total titulável e tempo de redução do azul de metileno no fluido ruminal de caprinos com ou sem raça definida, mantidos em pastagens artificiais, exclusivas de gramíneas, ou em caatinga, durante as épocas chuvosa e seca do ano. O delineamento experimental foi inteiramente casualizado, sendo analisado em esquema fatorial 2³ (animais com e sem raça definida, pastagens artificiais e em caatinga, épocas chuvosa e seca do ano). O tipo de pastagem influenciou significativamente (p < 0,05) os valores encontrados para acidez total titulável. em relação ao pH, o tipo de pastagem e época do ano foram significativamente (p < 0,05) os fatores mais incisivos. A atividade microbiana, avaliada através dos parâmetros estudados, foi mais intensa na época das águas e na caatinga em relação à da seca e pastagens artificiais, respectivamente. Na avaliação dos resultados desses testes, deve-se sempre levar em consideração principalmente a época do ano e o tipo de pastagem, sem, no entanto, desprezar o fator raça.

Flow cell within an LED: a proposal for an optical absorption detector

Droplets formed at the tip of a tube under the same conditions possess extreme uniformity of form, volume and weight. These properties of liquid drop formation have been known for a long time and consequently many applications for the drop have been found in instrumentation and chemical analysis methods. In the present paper, we report on the analytical use of a dynamic LED-based flow-through optical absorption detector with optical path length controlled by continuous dropping of a solution. This arrangement consists of a flow cell built within a high-intensity red LED (lambda (max)=630 nm). The feasibility of the detector is demonstrated by colorimetric determination of methylene blue, and ammonium by Berthelot's reaction, in a flow-injection system. For ammonium, the reaction forms a blue dye (indophenol) with a maximum absorption at 630-650 nm. The detection limit, considered as 3 times the signal of the blank, is better than 125 mu g l(-1). The small flow cell represents a good combination of optical path length, low volume and fast washout. This detector can be used advantageously in automated methods and can represent a solution to problems of optical detection involving gas bubbles and precipitation of particles in turbidimetric applications.

Decreased endothelium-dependent vasoconstriction to noradrenaline in acute-stressed rats is potentiated by previous chronic stress: Nitric oxide involvement

1. The objective was to determine whether nitric oxide participates in stress adaptive responses. Acute stress (AS) decreased endothelium-dependent vasoconstriction to noradrenaline (NA) in rat aorta [control rat (CR) 3.90+/-0.18, n=22; AS 2.76+/-0.20, n=13; P<0.05].2. Chronic stress exposure previous to AS (CS) potentiated this effect [CS 1.93+/-0.19; n=9; P<0.05 related to CR, P<0.05 related to AS].3. Methylene blue and N-G monomethyl-L-arginine, but not indomethaein, restored the decreased aorta reactivity to NA. 4. No reactivity alteration was observed in aorta without endothelium either in both stress conditions or in the presence of inhibitors. These data show that the nitric oxide participates in stress responses. (C) 1998 Elsevier B.V.

Rapid spot test analysis for the detection of urotropine in pharmaceutical preparations

The widespread falsification and/or adulteration of commercially available pharmaceutical preparations call for reliable methods of drug identification, preferably through selective and rapid sorting color tests that could be undertaken with minimum equipment remote from laboratory facilities. The present work deals with a convenient adaptation and refinement of a spot test devised by Feigl (1966) for urotropine, based on the hydrolytic cleavage of that substance in the presence of sulfuric acid, splitting out formaldehyde which is identified by its color reaction with chromotropic acid. A simple emergency kit was developed for the quick, efficient, inexpensive and easy performance of urotropine tests by semiskilled personnel even in the drugstore laboratory (or office) as well as in a mobile screening operation. It is shown that when the reagents are added according to the recommended sequence a self-heating system is generated, increasing substantially the reactions' rates and the test sensitivity as well. The identification limit found was 25 mug of urotropine, for both solid and liquid samples. The possible interference of 84 substances/materials was investigated. Interference was noted only for methylene blue, acriflavine, Ponceau Red, Bordeaux Red (these dyes are often included in urotropine dosage forms), pyramidone, dipyrone, quinine and tetracycline. A simple procedure for removing most of the interferences is described. Data for 8 commercial dosage forms and results obtained from their analysis are presented.