Assessment of simulated mandibular condyle bone lesions by cone beam computed tomography

There are many limitations to image acquisition, using conventional radiography, of the temporomandibular joint (TMJ) region. The Computed Tomography (CT) scan is a better option, due to its higher accuracy, for purposes of diagnosis, surgical planning and treatment of bone injuries. The aim of the present study was to analyze two protocols of cone beam computed tomography for the evaluation of simulated mandibular condyle bone lesions. Spherical lesions were simulated in 30 dry mandibular condyles, using dentist drills and drill bits sizes 1, 3 and 6. Each of the mandibular condyles was submitted to cone beam computed tomography (CBCT) using two protocols: 1) axial, coronal and sagittal multiplanar reconstruction (MPR); and 2) sagittal plus coronal slices throughout the longitudinal axis of the mandibular condyles. For these protocols, 2 observers analyzed the CBCT images independently, regarding the presence or not of injuries. Only one of the observers, however, performed on 2 different occasions. The results were compared to the gold standard, evaluating the percentage of agreement, degree of accuracy of CBCT protocols and observers' examination. The z test was used for the statistical analysis. The results showed there were no statistically significant differences between the 2 protocols. There was greater difficulty in the assessment of small-size simulated lesions (drill # 1). From the results of this study, it can be concluded that CBCT is an accurate tool for analyzing mandibular condyle bone lesions, with the MPR protocol showing slightly better results than the sagittal plus coronal slices throughout the longitudinal axis.

Heat treatment of a direct composite resin: influence on flexural strength

The purpose of this study was to evaluate the flexural strength of a direct composite, for indirect application, that received heat treatment, with or without investment. One indirect composite was used for comparison. For determination of the heat treatment temperature, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed, considering the initial weight loss temperature and glass transition temperature (Tg). Then, after photoactivation (600 mW/cm² - 40 s), the specimens (10 x 2 x 2 mm) were heat-treated following these conditions: 170ºC for 5, 10 or 15 min, embedded or not embedded in investment. Flexural strength was assessed as a means to evaluate the influence of different heat treatment periods and investment embedding on mechanical properties. The data were analyzed by ANOVA and Tukey's test (α = 0.05). TGA showed an initial weight loss temperature of 180ºC and DSC showed a Tg value of 157°C. Heat treatment was conducted in an oven (Flli Manfredi, Italy), after 37°C storage for 48 h. Flexural strength was evaluated after 120 h at 37°C storage. The results showed that different periods and investment embedding presented similar statistical values. Nevertheless, the direct composite resin with treatments presented higher values (178.7 MPa) compared to the indirect composite resin (146.0 MPa) and the same direct composite submitted to photoactivation only (151.7 MPa). Within the limitations of this study, it could be concluded that the heat treatment increased the flexural strength of the direct composite studied, leading to higher mechanical strength compared to the indirect composite.

Constituintes químicos e atividade antimicrobiana dos extratos de Dilodendron bipinnatum (sapindaceae)

The phytochemical investigation of ethanolic extracts from leaves, branches and stems of D. bipinnatum afforded the steroids β-sitosterol, stigmasterol, campesterol, sitostenone and sitosterol-3-O-β-D-glycopyranoside, along with two cycloartane triterpenes: cycloeucalenol and 24-methylenecycloartenol. The antimicrobial activity of the extracts was evaluated against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Bacillus subtilis (ATCC 6623), Pseudomonas aeruginosa (ATCC 15442), Micrococcus luteus (ATCC 9341) and Candida albicans (ATCC 10231). The extracts of the leaves and branches showed moderate activity against Candida albicans. The extract of the branches was active against Micrococcus luteus. This is the first report on the phytochemical study of D. bipinnatum.

Participation of neuronal nitric oxide synthase in experimental neuropathic pain induced by sciatic nerve transection

Nerve injury leads to a neuropathic pain state that results from central sensitization. This phenomenom is mediated by NMDA receptors and may involve the production of nitric oxide (NO). In this study, we investigated the expression of the neuronal isoform of NO synthase (nNOS) in the spinal cord of 3-month-old male, Wistar rats after sciatic nerve transection (SNT). Our attention was focused on the dorsal part of L3-L5 segments receiving sensory inputs from the sciatic nerve. SNT resulted in the development of neuropathic pain symptoms confirmed by evaluating mechanical hyperalgesia (Randall and Selitto test) and allodynia (von Frey hair test). Control animals did not present any alteration (sham-animals). The selective inhibitor of nNOS, 7-nitroindazole (0.2 and 2 µg in 50 µL), blocked hyperalgesia and allodynia induced by SNT. Immunohistochemical analysis showed that nNOS was increased (48% by day 30) in the lumbar spinal cord after SNT. This increase was observed near the central canal (Rexed’s lamina X) and also in lamina I-IV of the dorsal horn. Real-time PCR results indicated an increase of nNOS mRNA detected from 1 to 30 days after SNT, with the highest increase observed 1 day after injury (1469%). Immunoblotting confirmed the increase of nNOS in the spinal cord between 1 and 15 days post-lesion (20%), reaching the greatest increase (60%) 30 days after surgery. The present findings demonstrate an increase of nNOS after peripheral nerve injury that may contribute to the increase of NO production observed after peripheral neuropathy.

Resultados preliminares de um algoritmo para ablação de lente de contato personalizada

OBJETIVO: Desenvolver simulação computadorizada de ablação para produzir lentes de contato personalizadas a fim de corrigir aberrações de alta ordem. MÉTODOS: Usando dados reais de um paciente com ceratocone, mensurados em um aberrômetro ("wavefront") com sensor Hartmann-Shack, foram determinados as espessuras de lentes de contato que compensam essas aberrações assim como os números de pulsos necessários para fazer ablação as lentes especificamente para este paciente. RESULTADOS: Os mapas de correção são apresentados e os números dos pulsos foram calculados, usando feixes com a largura de 0,5 mm e profundidade de ablação de 0,3 µm. CONCLUSÕES: Os resultados simulados foram promissores, mas ainda precisam ser aprimorados para que o sistema de ablação "real" possa alcançar a precisão desejada.

Utilização de um espectrógrafo de projeção como uma ferramenta para demonstrações sobre polarização da luz

This article describes the use of a projection spectrograph based on an overhead projector for use in classroom demonstrations on light polarization and optical activity. A simple adaptation on a previously developed apparatus allows illustrating several aspects of optical activity, such as circular and linear birefringence, including their wavelength dependence. Specifically, we use the projection spectrograph to demonstrate the optical activity of an aqueous solution of sugar (circular birefringence), of a quartz plate and of an overhead projector transparence film (linear birefringence). A historical survey about the optical activity discovery and the main principles involved is also presented.

Análises do matching de identidade generalizado por contingências de três e quatro termos: implicações para equivalência de estímulos

A expansão da tríplice continência em unidades com quatro ou mais elementos abriu novas perspectivas para a compreensão de comportamentos complexos, como a emergência de respostas que derivam da formação de classes de estímulos equivalentes e que modelam comportamentos simbólicos e conceituais. Na investigação experimental, o procedimento de matching to sample tem sido frequentemente empregado para estabelecer discriminações condicionais. Em particular, a obtenção do matching de identidade generalizado é considerada demonstrativa da aquisição dos conceitos de igualdade e diferença. Segundo argumentamos, o fato de se buscar a compreensão desses conceitos a partir de processos discriminativos condicionais pode ter sido responsável pelos frequentes fracassos em demonstrá-los em sujeitos não humanos. A falta de correspondência entre os processos discriminativos responsáveis por estabelecer a relação de reflexividade entre estímulos que formam classes equivalentes e o matching de identidade generalizado, nesse sentido, é aqui revista ao longo de estudos empíricos e discutida com respeito às suas implicações.

Detecção de estímulos concêntricos mesópicos em crianças surdas e ouvintes

O objetivo deste trabalho foi medir curvas de sensibilidade ao contraste de 10 crianças ouvintes e de 10 crianças com surdez pré-lingual, de 7 a 12 anos, utilizando frequências radiais circularmente concêntricas (FSCr) de 0,25-2,0 cpg em níveis baixos de luminância (0,7 cd/m²). Todos os participantes apresentavam acuidade visual normal e estavam livres de doenças oculares identificáveis. A FSCr foi medida com o método psicofísico da escolha forçada. Os resultados mostraram sensibilidade máxima na faixa de frequência radial de 0,25 cpg para os dois grupos. Os resultados mostraram ainda diferenças significantes entre as curvas de FSCr de crianças ouvintes e de crianças com surdez pré-lingual. Isto é, as crianças ouvintes precisaram de menos contraste do que as crianças surdas para detectar as frequências radiais. Esses resultados sugerem que, em níveis baixos de luminância, a FSCr das crianças ouvintes foi melhor do que a das crianças com surdez pré-lingual.

Estudo da decomposição térmica de propelente sólido compósito de baixa emissão de fumaça

The thermal decomposition of hydroxyl-terminated polybutadiene (HTPB)/ammonium nitrate (AN) based propellants, so called smokeless formulations, and raw materials were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). The thermoanalytical profile of different components and of propellant were evaluated and the Arrhenius parameters for the thermal decomposition of the propellant sample were determined by the Ozawa method. The kinetic parameters of the thermal decomposition of propellant samples were determined by DSC measurements. The values obtained for activation energy (Ea) and pre-exponential factor were 163 kJ mol-1 and 1.94x10(6) min-1.

Caracterização de cálculos renais por análise térmica

Dez amostras de cálculos renais foram estudadas por Análise Elementar de CHN (EA), Espectroscopia de Absorção no Infravermelho (IV) e Difração de raios X pelo método de Pó (XRD). O comportamento térmico das amostras foi estudado por Termogravimetria/Termogravimetria Derivada (TG/DTG) e por Calorimetria Exploratória Diferencial (DSC). Os resultados de EA, Espectroscopia de Absorção IV e XRD mostraram a presença de estruvita [NH4Mg(PO4).6H2O], apatita, oxalato de cálcio monohidratado e oxalato de cálcio dihidratado. As curvas TG e DSC permitiram classificar as amostras em dois grupos diferentes: Grupo I mostrando comportamento térmico típico de estruvita e Grupo II apresentando um perfil termoanalítico característico de mistura de oxalatos.

Thermal behavior and decomposition kinetics of rifampicin polymorphs under isothermal and non-isothermal conditions

The thermal behavior of two polymorphic forms of rifampicin was studied by DSC and TG/DTG. The thermoanalytical results clearly showed the differences between the two crystalline forms. Polymorph I was the most thermally stable form, the DSC curve showed no fusion for this species and the thermal decomposition process occurred around 245 ºC. The DSC curve of polymorph II showed two consecutive events, an endothermic event (Tpeak = 193.9 ºC) and one exothermic event (Tpeak = 209.4 ºC), due to a melting process followed by recrystallization, which was attributed to the conversion of form II to form I. Isothermal and non-isothermal thermogravimetric methods were used to determine the kinetic parameters of the thermal decomposition process. For non-isothermal experiments, the activation energy (Ea) was derived from the plot of Log β vs 1/T, yielding values for polymorph form I and II of 154 and 123 kJ mol-1, respectively. In the isothermal experiments, the Ea was obtained from the plot of lnt vs 1/T at a constant conversion level. The mean values found for form I and form II were 137 and 144 kJ mol-1, respectively.

Effect of experimental heat treatment on mechanical properties of resin composites

The aim of this study was to verify the influence of an experimental heat treatment (170ºC/10 min) using a casting furnace on the mechanical properties (hardness and flexural strength) of 2 commercial direct resin composites (TPH Spectrum and Filtek P60) compared to a commercial indirect resin system (BelleGlass). Heat treatment temperature was determined after thermal characterization by thermogravimetry (TG) and differential scanning calorimetry (DSC). Data was analyzed by ANOVA and Tukey's test at 5% significance level. There was statistical significance for the main factor heat treatment (p=0.03) and composite (p=0.02), for flexural strength. For Knoop hardness, only the main factor composite was statistically significant (p=0.00). P60 presented higher hardness than TPH. No statistically significant correlation between mechanical properties tested was detected. Based on these results, it was possible to conclude that heat treatment influenced flexural strength of direct composites, while it was not observed for hardness. The association of direct composites with a simple post-cure heat treatment may be an alternative for current indirect composite systems, although more studies are needed to verify other properties of the composites for this application.

Time trends and predictors of mortality from ill-defined causes in old age: 9 year folllow-up of the Bambuí cohort study (Brazil)

The study objective was to examine differentials in time trends and predictors of deaths assigned to symptoms, signs and ill-defined conditions in comparison with other ill-defined conditions (ill-defined cardiovascular diseases, cancer and injury) in a population-based cohort study. Of 1,606 baseline participants aged 60 years and over, 524 died during 9-year follow-up and were included in this study. Deaths coded to "symptoms" declined by 77% in the period from 1997-1999 to 2003-2005. Deaths coded to other ill-defined conditions remained unchanged. The calendar period 2003-2005 (RR = 0.25; 95%CI: 0.09-0.70) and in-hospital deaths (RR = 0.16; 95%CI: 0.08-0.34) were independently associated with "symptoms", but not with other ill-defined conditions. Baseline socio-demographic characteristics and chronic diseases were not predictors of these outcomes. International and national agencies have focused on the reduction of deaths assigned to "symptoms" to improve the registration of vital statistics, while other ill-defined conditions have received little attention. Our data provide evidence supporting the need to redress this situation.

Condições socioeconômicas e padrões alimentares de crianças de 4 a 11 anos: estudo SCAALA - Salvador/ Bahia

OBJETIVOS: identificar os padrões alimentares de crianças e sua associação com o nível socioeconômico das famílias. MÉTODOS: estudo transversal com 1260 crianças de 4 a 11 anos, residentes em Salvador-Bahia que incluiu aplicação de um Questionário de Frequência Alimentar semi-quantitativo. Os padrões alimentares foram identificados, empregando-se análise fatorial por componentes principais. O nível socioeconômico foi avaliado por meio de um indicador socioeconômico composto. Regressão logística multivariada foi empregada. RESULTADOS: identificaram-se quatro padrões que explicaram 45,9% da variabilidade dos dados de frequência alimentar. Crianças que pertencem ao nível socioeconômico mais alto têm 1,60 vezes mais chance (p<0,001) de apresentarem maior frequência de consumo de alimentos do padrão 1 (frutas, verduras, leguminosas, cereais e pescados) e 3,09 vezes mais chance (p<0,001) de apresentarem maior frequência de consumo dos alimentos do padrão 2 (leite/ derivados, catchup/ maionese/ mostarda e frango), quando se compara com aquele de crianças de nível socioeconômico mais baixo. Resultado inverso foi observado no padrão 4 (embutidos, ovos e carnes vermelhas); isto é, quanto maior o nível socioeconômico menor a chance da adoção desse padrão. Tendência similar foi notada para o padrão 3 (frituras, doces, salgadinhos, refrigerante/ suco artificial). CONCLUSÕES: padrões alimentares de crianças são dependentes das condições socioeconômicas das famílias e a adoção de itens alimentares mais saudáveis associa-se aos grupos de mais altos níveis socioeconômicos.

Serological survey of Rickettsia sp. in horses and dogs in an non-endemic area in Brazil

Brazilian Spotted Fever (BSF) is a lethal rickettsiosis in humans caused by the bacteria Rickettsia rickettsii, and is endemic in some areas of Brazil. Horses and dogs are part of the disease's life cycle and they may also serve as sentinel animals in epidemiological studies. The first human BSF case in the State of Paraná was reported in 2005. The present study was conducted in the municipality of Almirante Tamandaré, where no previous case of BSF was reported. Serum samples were collected from 71 horses and 20 dogs from nine properties in the area. Ticks were also collected from these animals. All farmers completed a questionnaire about their knowledge of BSF and animal health management. Serum samples were analyzed by indirect immunofluorescent-antibody assay (IFA) using R. rickettsii and R. parkeri as antigens. Ticks were analyzed by PCR for Rickettsia sp., and all of them were PCR-negative. Six horses (8.45%) and 4 dogs (20%) were identified as seropositive. Farmers were not aware of the correlation between the presence of ticks and risk of BSF. Although a non-endemic area, Almirante Tamandaré is a vulnerable environment for BSF and effective tick control measures are required.