RESUMO
Electrospun materials have been widely explored for biomedical applications because of their advantageous characteristics, i.e., tridimensional nanofibrous structure with high surface-to-volume ratio, high porosity, and pore interconnectivity. Furthermore, considering the similarities between the nanofiber networks and the extracellular matrix (ECM), as well as the accepted role of changes in ECM for hernia repair, electrospun polymer fiber assemblies have emerged as potential materials for incisional hernia repair. In this work, we describe the application of electrospun non-absorbable mats based on poly(ethylene terephthalate) (PET) in the repair of abdominal defects, comparing the performance of these meshes with that of a commercial polypropylene mesh and a multifilament PET mesh. PET and PET/chitosan electrospun meshes revealed good performance during incisional hernia surgery, post-operative period, and no evidence of intestinal adhesion was found. The electrospun meshes were flexible with high suture retention, showing tensile strengths of 3 MPa and breaking strains of 8-33%. Nevertheless, a significant foreign body reaction (FBR) was observed in animals treated with the nanofibrous materials. Animals implanted with PET and PET/chitosan electrospun meshes (fiber diameter of 0.71 ± 0.28 µm and 3.01 ± 0.72 µm, respectively) showed, respectively, foreign body granuloma formation, averaging 4.2-fold and 7.4-fold greater than the control commercial mesh group (Marlex). Many foreign body giant cells (FBGC) involving nanofiber pieces were also found in the PET and PET/chitosan groups (11.9 and 19.3 times more FBGC than control, respectively). In contrast, no important FBR was observed for PET microfibers (fiber diameter = 18.9 ± 0.21 µm). Therefore, we suggest that the reduced dimension and the high surface-to-volume ratio of the electrospun fibers caused the FBR reaction, pointing out the need for further studies to elucidate the mechanisms underlying interactions between cells/tissues and nanofibrous materials in order to gain a better understanding of the implantation risks associated with nanostructured biomaterials.
Assuntos
Materiais Biocompatíveis/farmacologia , Quitosana/farmacologia , Reação a Corpo Estranho/induzido quimicamente , Granuloma de Corpo Estranho/induzido quimicamente , Nanofibras/química , Polietilenoglicóis/farmacologia , Telas Cirúrgicas/veterinária , Animais , Materiais Biocompatíveis/química , Quitosana/química , Modelos Animais de Doenças , Técnicas Eletroquímicas , Reação a Corpo Estranho/patologia , Granuloma de Corpo Estranho/patologia , Hérnia Abdominal/cirurgia , Herniorrafia/instrumentação , Masculino , Teste de Materiais , Polietilenoglicóis/química , Polietilenotereftalatos , Polipropilenos/farmacologia , Ratos , Ratos Wistar , Propriedades de Superfície , Suturas , Resistência à TraçãoRESUMO
Resumo O artigo apresenta um estudo que pretendeu compreender as ONG's como acontecimento discursivo que institui e coloca em circulação um discurso que se pretende verdadeiro sobre o esporte e sobre crianças e jovens despossuídos. Fez-se a análise dos discursos publicados nos sites de nove ONGs que centram sua ação na oferta de atividades esportivas para o público infanto-juvenil que vive em periferias urbanas. Concluiu-se que as ONGs conferem mais ênfase à própria ação do que aos sujeitos que as recebem; que os discursos sobre o esporte são informados por tradições políticas e discursivas que reforçam o valor dessa prática como ferramenta de disciplina e controle; e que crianças e jovens pobres são aproximados discursivamente da ociosidade, da criminalidade, da indisciplina e do desrespeito às regras.
Abstract The paper presents of a study that sought to understand the NGOs as discursive event that imposes and puts into circulation a speech intended to be true about themselves, about sport and about children and young people living in Brazilian urban outskirts. Assuming that NGOs are political-economic strategy of social financialization and device of disciplining and government of individuals and populations, it has been carried out an analysis of what has been publicized in the sites of 9 organizations that focus their activities on offer sports activities for the juvenile public. The findings show that the NGOs give more emphasis to their own action than to children and young people who receive them; that the speeches about the sport are informed by political and discursive traditions that reinforce the value of this practice as a tool of discipline and control; e that poor children and young are approximate discursively to vagrancy, crime, indiscipline and disrespect to the rules.
Resumen El artículo presenta un estudio en que se intenta entender a las ONG como acontecimiento discursivo que instituye y pone en circulación un discurso que se pretende verdadero sobre el deporte y sobre los niños y jóvenes desahuciados de la periferia urbana de Brasil. Se ha hecho un análisis de lo que se ha publicado en los sitios web de 9 organizaciones que centran sus actividades en la oferta de actividades deportivas para el público infantil y juvenil. Los resultados muestran que las ONG dan más importancia a su propia acción que a los niños y jóvenes que reciben; que los discursos sobre el deporte contienen tradiciones políticas y discursivas que refuerzan el valor de esta práctica como una herramienta de la disciplina y el control, y que se aproxima discursivamente a los niños y jóvenes pobres a la vagancia, la delincuencia, la indisciplina y la falta de respeto a las normas.