Antimicrobial Photodynamic Therapy (aPDT) for decontamination of high-speed handpieces: A comparative study.

BACKGROUND: Cross-transmission is a major concern in dental offices. Various disinfection methods have been frequently used to reduce its incidence. Standard procedures include decontamination and sterilization. Traditional decontamination methods include: Alcohol 70 % and chlorhexidine digluconate, however, antimicrobial photodynamic therapy (aPDT) could be added as an option. The objective was to evaluate the effectiveness of aPDT on decontamination of high-speed handpieces, contaminated by Staphylococcus aureus (SA) and Escherichia coli (EC), and compare it to autoclave sterilized and to conventional chemical decontamination methods. METHODS: Sterilized, SA and EC contaminated high-speed handpieces were divided in 7 groups: G1- sterilized in an autoclave. G2- contaminated untreated control. G3- contaminated and decontaminated using Alcohol 70 %. G4- contaminated and decontaminated using chlorhexidine digluconate 2%. G5- contaminated and laser treated. G6- contaminated and photosensitizer treated. G7- contaminated and photodynamic therapy. RESULTS: The groups G3, G4, G7 did not show bacterial growth, G5 and G6 showed bacterial growth similar to G2. The study did not find SA or EC sensible to laser irradiation only, differently from some authors and did not consider biofilm in our experiments. CONCLUSION: Our experiment showed that, laser and photosensitizer isolated were not effective to inhibit Staphylococcus aureus (SA) and Escherichia coli (EC) growth, but when associated in aPDT technique, can be compared to chemical disinfection agents that are traditionally used and effective against this pathogen.

The impact of dietary protein levels on nutrient digestibility and water and nitrogen balances in eventing horses.

This study was performed to evaluate the impact of dietary protein levels on nutrient digestibility and water and nitrogen balances in conditioning eventing horses. Twenty-four Brazilian Sport Horses, male and female (8.0 to 15.0 yr; 488 ± 32 kg BW), were used in a randomized design with 4 levels of CP diets: 7.5%, 9.0%, 11.0%, and 13.0%. A digestion assay was performed with partial feces collection over 4 d, followed by 1 d of total urine collection. Data were submitted to regression analysis and adjusted to linear and quadratic models (P < 0.05). No differences were observed in the intake of DM, OM, EE, ADF, and NDF as a function of dietary protein levels. Dry matter intake average was 1.7% of BW. CP and N intake showed a linear increase as a function of increasing protein level in diets. A quadratic response (P < 0.05) was observed on the CP and NDF digestibility coefficients, with the maximum estimated level of digestibility at 11.6% and 11.4% CP in the diet, respectively. There was a linear effect on ADF digestibility coefficients, digestible DM and protein intake, and CP/DE ratio according to dietary protein levels. There was no impact of dietary protein levels on daily water intake, total water intake, or fecal water excretion. Urinary excretion values showed a linear increase in response to increased dietary protein levels, but no impact was observed on water balance, with an average of 8.4 L/d. Nitrogen intake (NI), N absorption (NA), and urinary N increased linearly as a function of increasing dietary protein levels. There was no impact of dietary protein levels on N retention (NR), with an average of 7.5 g N/d. Nitrogen retention as a percentage of NI or NA showed no significant changes in the function of dietary protein levels. There was an impact of dietary protein levels on the digestibility coefficient of CP, NDF, ADF, and digestible protein intake on conditioning eventing horses. The 11.6% CP level in the diet provided an intake of 2.25 g CP/kg BW and 0.37 g N/kg BW, and this intake was the most appropriate for the conditioning of intensely exercised horses, considering the responses related to NI, NA, and the estimated NR to NA ratio. The NDF and ADF responses indicated that dietary fiber was more digested with an increased amount of N in the digestive tract.

Development and application of a dry ultramicrotomy technique for the preparation of galvanneal sheet coatings.

The formability of galvanneal steel sheets used in the automotive industry is influenced by the presence and distribution of brittle and difficult to distinguish Zn-Fe intermetallics in the coating. Characterization of these intermetallics requires a high spatial resolution technique such as analytical transmission electron microscopy (ATEM). Sample preparation by ion milling is impossible due to iron redeposition, and traditional ultramicrotomy using water affects the coating chemistry. A technique based on dry ultramicrotomy has therefore been developed. To optimize the technique, different parameters (knife angle, cutting medium, thickness setting on the ultramicrotome, cutting speed) have been investigated for the preparation of galvanneal coatings and pure A1 sections. Results show that dry cutting does not affect the coating chemistry but shortens the life of the knife. Knife quality (cleanliness, sharpness and absence of defects) is a major factor to obtain good dry sections. The best results for the more ductile pure A1 are obtained with a 35 degrees knife whilst for the harder galvanneal coating it is recommended to use a 55 degrees knife. These results suggest that the sectioning mechanism for the harder material involves more a cleavage-fracture mechanism whilst a greater amount of shear is involved when sectioning relatively ductile A1. The optimum parameters for sectioning galvanneal coatings are established and results obtained by parallel electron energy loss spectrum imaging and energy dispersive X-ray spectrometry in the TEM are given. This study shows that with a good control of all the sectioning parameters it is possible to obtain good sections repeatedly and rapidly.

Estudo comparativo entre a eficiencia de hemoculturas e xenodiagnosticos seriados efetuados em gambas do genero Didelphis, naturalmente infectados pelo Trypanosoma Cruzi. / Comparative study the efficiency of hemocultures and serial xenodiagosis performed in opossums of the genus Didelphis, naturally infected by Trypanosoma cruzi

Em ecotopos naturais de varios municipios dos Estados de Sao Paulo e Minas Gerais foram capturados gambas do genero Didelphis, naturalmente infectados, dos quais foram selecionados 25 exemplares de cada subespecie, D. albiventris e D. aurita.Nestes animais foram feitos 4 hemoculturas (5 tubos de cada vez) e 4 xenodiagnosticos seriados (5 insetos de cada especie), sendo utilizado o meio de Warren e as especies de triatomineos Panstrongylus megistus Triatoma sordida e Rhodnius neglectus, com intervalo de uma semana entre cada repeticao. Os resultados foram submetidos a analise de varianca e ao teste de Duncan, o qual demonstrou que houve um aumento de eficiencia dos dois metodos, a medida em que sao repetidos os exames e que os xenodiagnosticos sempre foram superiores as hemoculturas

Estudos sobre reservatorios e vectores silvestres do Trypanossoma cruzi. LXXVII Observacoes sobre a ecologia do Triatoma arthurneivai Lent & Martins, 1940. / Wild reservoirs and vectors of Trypanosoma cruzi. LXXVII: Observations on the ecology of the Triatoma arthurneivai Lent and Martins, 1940

Pesquisas realizadas em ecotopos silvestres em municipios do Alto Sao Francisco, M.G., levaram ao encontro de ninfas e adultos do T.arthurneivai em Divinopolis, Itauna, Bom Despacho e Para de Minas. O triatomineo so foi encontrado entre pedras amontoadas e muros de pedras arruinados ou, em fendas e cavidades de rochas. Nesses ecotopos, convive com pequenos roedores e com largatixas sobre os quais se alimentam. Dois exemplares, uma femea e uma ninfa, cujo conteudo do tubo digestivo deu reacoes de precipitina positivas com soro anti-rato, mostraram-se infectados por tripanossomos identificados como T. cruzi em camundongos jovens com eles infectados