L929 cell response to root perforation repair cements: an in vitro cytotoxicity assay

This study compared the cytotoxicity of an experimental epoxy-resin and calcium hydroxide-based cement (MBPc), gray mineral trioxide aggregate (MTA) and white mineral trioxide aggregate (WMTA) using the agar overlay method with neutral red dye. L929 cells were seeded into 6-well culture plates where 48-h set test materials were placed on the agar overlay, in triplicate. Teflon and natural rubber served as negative and positive controls. After an incubation period of 24 h at 37ºC in a humidified atmosphere of 5 percent CO2 in air, a discolored area around the samples and the positive controls could be observed and measured per quadrant. The mean values were compared and converted into grades to classify the results according to the table of cytotoxicity grades according to the Standard Operating Procedures (SOP) of the Oswaldo Cruz Foundation, Brazil. The nonviable cell areas and the morphological changes in the cells were observed with an inverted microscope. The results showed grade 1 (slight) for the two types of MTA (p>0.05) and grade 2 (mild) for the MBPc (p<0.001). All samples met the requirements of the test as none of the cultures showed reactivity higher than grade 2.

O objetivo deste estudo foi comparar a citotoxicidade de um cimento experimental à base de resina epóxica e hidróxido de cálcio (MBPc), do agregado trióxido mineral (MTA) cinza e do MTA branco, utilizando o ensaio de difusão em agar com o corante vermelho neutro. Células L929 foram semeadas em placas de 6 poços e sobre elas a camada de agar, onde foram colocados os materiais endurecidos por 48 h, em triplicata, além de teflon como controle negativo e látex como controle positivo. Após 24 h em estufa umidificada a 37ºC com 5 por cento CO2, um halo claro se formou ao redor das amostras e dos controles positivos. As medidas foram tomadas, por quadrante, e as médias foram comparadas e convertidas em graus para qualificar os resultados, de acordo com a tabela de grau de citotoxicidade do POP/FIOCRUZ. As zonas de inibição e as alterações da morfologia celular foram avaliadas sob microscópio invertido. Os resultados revelaram grau 1 (leve) para os dois tipos de MTA (p>0,05) e grau 2 (branda) para o MBPc (p<0,001). Todas as amostras foram consideradas satisfatórias, pois nenhuma cultura exposta aos cimentos revelou toxicidade superior ao grau 2.

Evaluation of respiratory model employing conventional NIH mice to access the immunity induced by cellular and acellular pertussis vaccines

The increasing number of pertussis cases reported on the last twenty years and the existence of new acellular vaccines reinforce the need of research for experimental models to assure the quality of available pertussis vaccines. In this study, allotments of whole-cell and acellular pertussis vaccines were tested through the Intranasal Challenge Model (INM) using conventional NIH mice. The results have been compared to those achieved by the "Gold standard" Intracerebral Challenge Model (ICM). In contrast to ICM, INM results did not show intralaboratorial variations. Statistical analysis by Anova and Ancova tests revealed that the INM presented reproducibility and allowed identification and separation of different products, including three-component and four-component accellular pertussis vaccines. INM revealed differences between pertussis vaccines. INM provides lower distress to the mice allowing the reduction of mice number including the possibility of using conventional mice (less expensive) under non-aseptic environment. Thus, INM may be used as an alternative method of verifying the consistence of allotment production, including acellular pertussis vaccines.