Ionizing Radiation Effects On The Secretory-stage Ameloblasts And Enamel Organic Extracellular Matrix

This study assessed the effects of high doses of ionizing radiation on eruption rate, odontogenic region morphology, secretory-stage ameloblasts, and enamel organic extracellular matrix (EOECM) of rat maxillary incisors. For the study, 30 male rats were divided into three experimental groups: control (non-irradiated), irradiated by 15 Gy, and irradiated by 25 Gy. Irradiated groups received a single dose of 15 or 25 Gy of X-rays in the head and neck region. The maxillary incisor eruption rate was measured. Sections of 5-μm thickness of the maxillary incisor odontogenic regions were evaluated using bright field light microscopy. Ultrathin sections of secretory ameloblasts and their EOECM were analyzed by transmission electron microscopy (TEM). Irradiated groups showed significantly diminished eruption rate values at the 4th and at the 6th day after irradiation. Reduced optical retardation values were observed in the irradiated groups. The odontogenic region of maxillary incisors from irradiated rats exhibited altered and poorly organized preameloblasts. TEM showed degeneration areas in the secretory-stage EOECM and several autophagosomes in the secretory ameloblasts from irradiated animals. In conclusion, high radiation doses delay eruption and induce disturbances in secretory ameloblasts and EOECM of rat maxillary incisors. These findings may be associated with structural defects of mature enamel. © 2014 Springer-Verlag Berlin Heidelberg

Análise de coberturas com telhas de barro e alumínio, utilizadas em instalações animais para duas distintas alturas de pé-direito The analysis of ceramic tile and aluminum covers, used in animal facilities for two different foot-right heights

Este trabalho teve como objetivo a análise de coberturas com telhas de barro e alumínio, comumente utilizadas em instalações animais, para duas distintas alturas de pé-direito, em condições de inverno no Brasil. O experimento foi realizado com modelos reduzidos de galpões avícolas, escala 1:10, e a análise foi feita quantificando-se a Carga Térmica de Radiação (CTR) e o Índice de Temperatura de Globo Negro e Umidade (ITGU) em diferentes horários, ao longo do período experimental. O experimento foi montado segundo um esquema de parcelas subdivididas, no delineamento em blocos casualizados. A interpretação estatística dos dados experimentais foi feita por meio da análise de variância e regressão. Para os fatores qualitativos (tipos de cobertura e pé-direito) as médias foram comparadas utilizando-se o teste de Tukey e/ou F, adotando-se o nível de 5% de probabilidade; já para o fator quantitativo, os modelos foram escolhidos com base na significância dos coeficientes de regressão, utilizando-se o teste t em nível de 5% de probabilidade, o coeficiente de determinação e o fenômeno em estudo. Verificou-se, através deste experimento, que nas horas de frio mais intenso todas as coberturas causaram desconforto térmico e todos os protótipos tiveram UR acima do máximo tolerável para o conforto animal.<br>This research had as objective the analysis of ceramic tiles and aluminum roof, commonly used in animal facilities, for two different heights, under Brazilian Winter conditions. The experiment used reduced models of poultry houses (scale 1:10) and the analysis was made by the values of Thermal Load of Radiation (TLR) and of Black Globe and Humidity Index (BGHI), at different times along the experiment. The trial was conducted in randomized complete block design. The statistical interpretation of the experimental data was made through the variance and regression analysis. For the qualitative factors (roof types and height), the means were compared using the Tukey's and/or F test, at 5% level of probability. For the quantitative factors, the models were chosen based on the significance of the regression coefficients, applying the t test, at 5% level of probability, the determination coefficient and the studied phenomena. It was verified through this experiment that during the hours of more intense cold, all the coverings caused thermal discomfort and all the prototypes had relative humidity above the tolerable maximum for the animal comfort