The Effect of Physicochemical Properties on the Multiwalled Carbon Nanotube-induced Genotoxicity and Carcinogenesis

Multiwalled carbon nanotubes (MWCNT) are one of the most exciting industrial materials of our time. They are used in life-saving medical therapeutics and many commercial products that could make day-to-day life seem effortless. However, previous toxicological research has demonstrated this material to be significantly genotoxic in both in vitro and in vivo models and potentially carcinogenic in the lung. The unique physiochemical properties of MWCNT make respiratory exposures likely in workers. Combining the genotoxic effects with the potential for lung deposition in the workplace, MWCNT should be considered as a potential health hazard. Altering the physiochemical properties of MWCNT has been shown to effect toxicity, however there has been limited research on how this effects the mechanism of genotoxicity and carcinogenicity.;Therefore, the aim of the first study was to determine the effect of MWCNT diameter on the mechanism of genotoxicity. Previous research has demonstrated that exposure to MWCNT material both in vitro and in vivo induces DNA damage leading to significant aneuploidy. It is known that the microtubules that make up the mitotic spindle are 20 nm in diameter. Therefore, human lung epithelial cells were exposed to MWCNT material 10-20 nm in diameter at occupationally-relevant doses. Significant genotoxicity was observed as arrests in the G1/S phase of the cell cycle. Exposure to MWCNT led to significantly increased mitotic spindle aberrations that were predominately monopolar in morphology and fragmented centrosomes. Exposure to the highest dose produced 62% aneuploidy cells that was significantly greater than control. Aneuploidy was the result of both gains and losses of chromosomes 1 and 4.;The aim of the second study was to determine the effect of MWCNT chemical composition on the mechanism of genotoxicity. Previous research has demonstrated that eliminating metal contaminates in the MWCNT through high-temperature treatment post-synthesis (MWCNT-HT) or incorporating nitrogen into the lattice structure of the walls of MWCNT structure during synthesis (MWCNT-ND) can potentially reduce the toxicity of the pristine material (MWCNT-7). Therefore, two types of human lung epithelial cells were exposed to MWCNT-7, MWCNT-HT, and MWCNT-ND in a dose-response. Significant genotoxicity was observed in two cell types through arrests in the cell cycle that indicate centrosomal damage after exposure to each MWCNT material. Exposure to each MWCNT material also led to significantly increased mitotic spindle aberrations and fragmented centrosomes. Exposure to the highest dose of MWCNT-7, HT and ND material produced 65, 58, and 53% aneuploidy cells, respectively. Detailed chromosome analysis demonstrated significantly increased frequency of fragmented centromeres and translocations between chromosomes 1 and 4.;The aim of the third study was to determine the mechanism of carcinogenicity of inhaling MWCNT-7 material via a two-stage initiation-promotion protocol. Previous research demonstrated the MWCNT-7 material to be significantly genotoxic and the potential for MWCNT material to be a tumor promoter. At 17 months post-exposure, 23.2, 51.9, 26.5, and 90.5% of mice from the control, initiating agent only, MWCNT-7 only, or initiating agent and MWCNT-7 group, respectively, had lung tumors. The tumor multiplicity, potency, and volume in the latter group was significantly greater than control indicating that MWCNT-7 material is a strong tumor promoter. Additionally, mice that received both initiating agent and MWCNT-7 demonstrated evidence of serosal tumors morphologically consistent with sarcomatous mesotheliomas.;In conclusion, these studies indicate that MWCNT material, regardless of physicochemical modification, is significantly genotoxic by disrupting the mitotic spindle and fragmenting centrosomes leading to significant aneuploidy. The MWCNT-7 material produced the greatest amount of aneuploidy. Inhalation exposure to this material was significantly carcinogenic and shown to work through the mechanism of tumor promotion rather than initiation

Experimental Determination of the Transversal and Longitudinal Fibre Bundle Permeability

In the resin transfer moulding process, fabrics are very often used as reinforcement. These fabrics consist of fibre bundles. In this context, both the permeability of the macroscopic fabric and the permeability of the fibre bundle are the key parameters to accurately predict the impregnation of the fabrics, the impregnation time and resulting void content. The fibre bundle permeability can be either predicted theoretically or experimentally. Whereas the theoretical determination lacks on accuracy as the realistic packing of the fibres in the bundles is not integrated in the models. In this work, we present an experimental setup to measure the longitudinal and transversal permeability of fibre bundles. The results are compared to model prediction

Applying the effort-reward imbalance model to household and family work: a population-based study of German mothers

<p>Abstract</p> <p>Background</p> <p>This paper reports on results of a newly developed questionnaire for the assessment of effort-reward imbalance (ERI) in unpaid household and family work. Methods: Using a cross-sectional population-based survey of German mothers (n = 3129) the dimensional structure of the theoretical ERI model was validated by means of Confirmatory Factor Analysis (CFA). Analyses of Variance were computed to examine relationships between ERI and social factors and health outcomes.</p> <p>Results</p> <p>CFA revealed good psychometric properties indicating that the subscale 'effort' is based on one latent factor and the subscale 'reward' is composed of four dimensions: 'intrinsic value of family and household work', 'societal esteem', 'recognition from the partner', and 'affection from the child(ren)'. About 19.3% of mothers perceived lack of reciprocity and 23.8% showed high rates of overcommitment in terms of inability to withdraw from household and family obligations. Socially disadvantaged mothers were at higher risk of ERI, in particular with respect to the perception of low societal esteem. Gender inequality in the division of household and family work and work-family conflict accounted most for ERI in household and family work. Analogous to ERI in paid work we could demonstrate that ERI affects self-rated health, somatic complaints, mental health and, to some extent, hypertension.</p> <p>Conclusions</p> <p>The newly developed questionnaire demonstrates satisfied validity and promising results for extending the ERI model to household and family work.</p

Padronização de uma bateria para a avaliação de fatores de risco psicossociais trabalhistas em trabalhadores colombianos

A battery of questionnaires to assess psychosocial risk factors at work was developed in 2010 in response to Resolution 2646 created by the Colombian Ministry of Social Protection. However, this battery presents some theoretical and practical limitations. A new battery of instruments has been designed and validated that includes instruments and risk indicators of the demand-control-social support and the effort-reward imbalance models. Other factors, not included in these models, but that Resolution 2646 suggests should be assessed, have also been added, and with this additional information, the new battery allows us to also calculate a “global indicator” of demand, control, and social support; family and social risk conditions, coping and personality; and health and wellbeing. The new battery was administered to a sample of 16,095 workers from different occupations and representative Colombian regions. An analysis of the various domains indicates that internal consistency of the various scales is high. The new battery has the following properties: it is simple to use in paper format or when administered by computer, it enables comparison between occupations, it offers unified scores for each variable, and provides information to assess the risk factors suggested by Resolution 2646. In addition, it will make it possible to compare the results obtained when analyzing Colombian workers with those obtained from studies of workers from other countries.Em 2010, desenvolveu-se uma bateria de instrumentos para avaliar fatores psicossociais trabalhistas de risco para a saúde, em resposta à Resolução 2 646 do Ministério da Proteção Social da Colômbia. Contudo, esta conta com algumas limitações que, a partir da construção e da validação de uma nova bateria, neste estudo se pretendem superar. Além disso, a nova bateria oferece recursos adicionais para a avaliação desses fatores: a presente bateria incorpora os instrumentos e os indicadores centrais dos modelos demanda-controle-apoio social e desiquilíbrio esforço-recompensa e os fatores internos do trabalho não considerados nesses modelos, mas que a Resolução considera necessários, mediram-se com testes preexistentes ou desenvolvidos pelos autores. Com os dados coletados, é possível calcular indicadores globais de demanda, controle e apoio social; além de condições familiares e sociais de risco, enfrentamento, personalidade e indicadores de saúde e bem-estar. Para a validação, a bateria foi aplicada a uma amostra de 16 095 trabalhadores de diferentes cargos e municípios colombianos. As anál i ses de consistência interna e validade permitem afirmar que a bateria é simples de aplicar em papel ou digital, permitirá comparar cargos, obter pontuações unificadas por variável, oferecer um diagnóstico de um número importante das variáveis sugeridas na Resolução bem como permitirá comparar os resultados dos trabalhadores colombianos com os de outros países. Palavras-chave: fatores trabalhistas de risco psicossocial, Resolução 2 646 de 2008, modelo demanda-controle-apoio social, modelo desiquilíbrio esforço-recompensa, estresse profissional, avaliação.En 2010 se desarrolló una batería de instrumentos para evaluar factores psicosociales laborales de riesgo para la salud, en respuesta a la Resolución 2646 de 2008 del Ministerio de la Protección Social de Colombia. Sin embargo, esta cuenta con algunas limitaciones que, a partir de la construcción y validación de una nueva batería, en el presente estudio se buscan superar. La nueva batería ofrece recursos adicionales para la evaluación de estos factores: incorpora los instrumentos e indicadores centrales de los modelos demanda-control-apoyo social y desequilibrio esfuerzo-recompensa, y los factores intralaborales no contemplados en dichos modelos, pero que la Resolución considera necesarios, se midieron con pruebas preexistentes o desarrolladas por los autores. Con los datos recolectados es posible calcular indicadores globales de demanda, control y apoyo social; además de condiciones familiares y sociales de riesgo, afrontamiento, personalidad e indicadores de salud y bienestar. Para la validación, la batería se aplicó a una muestra de 16.095 trabajadores de diferentes ocupaciones y municipios colombianos. Los análisis de consistencia interna y validez permiten afirmar que la batería es sencilla de aplicar en papel o por computador, permitirá comparar ocupaciones, obtener puntuaciones unificadas por variable, ofrecer un diagnóstico de un número importante de las variables sugeridas en la Resolución y comparar los resultados de los trabajadores colombianos con los de otros países