José Antônio de Souza

Foreign body reaction associated with PET and PET/chitosan electrospun nanofibrous abdominal meshes.

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.

Caracterização reológica de sorvetes

O conhecimento do comportamento reologico e de grande importância no processamento, manuseio, controle de qualidade e desenvolvimento de produtos alimenticios. A literatura relata que a maioria dos alimentos apresenta comportamento nao newtoniano, em que a sua viscosidade pode variar com o tempo e com as condicoes de escoamento. Neste trabalho foi realizada a caracterizacao reologica de cinco diferentes tipos de sorvetes. As amostras nos sabores creme, creme light, limao, iogurte e soja banana foram fornecidas pela empresa Amoratto Sorvetes Artesanais, localizada na cidade de Florianopolis/SC. Os dados reologicos foram obtidos atraves de um reometro com geometria de cilindros concentricos. Os ensaios foram realizados em tres diferentes temperaturas (-2, 0 e 2 °C) e os resultados experimentais foram ajustados pelos modelos de Bingham, Casson, Herschel-Bulkley e Lei da Potencia. As diferentes amostras apresentaram comportamento nao newtoniano nas tres temperaturas. Os parâmetros reologicos (K e n) foram obtidos atraves do ajuste dos modelos e o da Lei da Potencia mostrou o melhor ajuste aos resultados, com coeficientes de correlacao (r) iguais a 0,99 para quatro das cinco amostras, nas tres diferentes temperaturas.

Influence of temperature, concentration and shear rate on the rheological behavior of malay apple (Syzygium malaccense) juice

O objetivo deste estudo foi avaliar o comportamento reologico do suco de jambo-vermelho, uma tradicional fruta da regiao amazonica com elevadas propriedades bioativas, a diferentes temperaturas e concentracoes de solidos soluveis. Os experimentos foram realizados em um reometro Brookfield R/S Plus, operando em geometria de cilindros concentricos. Os modelos reologicos da Lei da Potencia, Herschel-Bulkley, Mizrahi-Berk e Sisko foram utilizados para modelagem dos dados experimentais. O suco de jambo-vermelho (polpa e casca) apresentou comportamento pseudoplastico para todas as temperaturas e concentracoes, com indice de comportamento de fluxo menor que 1. O efeito da temperatura na viscosidade aparente das amostras foi analisado pela equacao de Arrhenius. A energia de ativacao aumentou com a diminuicao na concentracao dos solidos soluveis, atestando que, quanto menor a concentracao, maior a influencia da temperatura na viscosidade aparente. O efeito da concentracao de solidos soluveis foi descrito pela equacao exponencial. O fator exponencial aumentou sob aumento da temperatura, atestando que, quanto maior for a temperatura, maior sera o efeito dos solidos soluveis na viscosidade aparente das amostras. Por fim, um modelo matematico triparametrico, relacionando temperatura, concentracao de solidos soluveis e taxa de deformacao foi proposto, visando avaliar a influencia destes parâmetros na viscosidade aparente das amostras e, de forma satisfatoria, ajustou-se aos dados experimentais, com elevado indice de correlacao R2.

Reconstituição da válvula ileocecal em cães

PURPOSE The importance of keeping the ileocecal valve in the intestinal ressections has been reported by several authors. When preserved, the ileocecal valve was related to a longer survival and prevention of the short bowel syndrome, due to its ability to block the colonic content reflux into the ileum and to avoid the rapid empting of the ileal content into the cecum. It was assessed a tecnique of ileocecal valve reconstitution, based on vesicoureteral anti-reflux tecniques. METHODS Fourteen beagles were operated. Seven underwent ileocecal valve reconstitution following the tecnique proposed and in the other seven a simple end-to-end anastomosis was performed. To assess the new valve, it was done the clinical follow up, the microbiologic analysis and the manometric study. RESULTS Clinically, during 45 days of follow up, there was no difference between the dogs with and without ileocecal reconstitution. In the aerobic bacteria analysis, the predominant bacterium was Escherichia coli. Quantitatively, the cultures grew in an irregular way, so that it was not able to compare the bacterial growth between the groups with or without ileocecal valve. The new valve had a colo-ileal reflux pressure similar to that of the physiological valve (P > 0.05). However, when compared to the non valve group, the reflux pressures of the physiological valve and new valve were significantly higher, with P < 0.05 and P < 0.001, respectively. CONCLUSION In this study, the reconstituted ileocecal valve served as a barrier to the colo-ileal reflux just as the physiological valve does.PURPOSE: The importance of keeping the ileocecal valve in the intestinal ressections has been reported by several authors. When preserved, the ileocecal valve was related to a longer survival and prevention of the short bowel syndrome, due to its ability to block the colonic content reflux into the ileum and to avoid the rapid empting of the ileal content into the cecum. It was assessed a tecnique of ileocecal valve reconstitution, based on vesicoureteral anti-reflux tecniques. METHODS: Fourteen beagles were operated. Seven underwent ileocecal valve reconstitution following the tecnique proposed and in the other seven a simple end-to-end anastomosis was performed. To assess the new valve, it was done the clinical follow up, the microbiologic analysis and the manometric study. RESULTS: Clinically, during 45 days of follow up, there was no difference between the dogs with and without ileocecal reconstitution. In the aerobic bacteria analysis, the predominant bacterium was Escherichia coli. Quantitatively, the cultures grew in an irregular way, so that it was not able to compare the bacterial growth between the groups with or without ileocecal valve. The new valve had a colo-ileal reflux pressure similar to that of the physiological valve (P>0.05). However, when compared to the non valve group, the reflux pressures of the physiological valve and new valve were significantly higher, with P<0.05 and P<0.001, respectively. CONCLUSION: In this study, the reconstituted ileocecal valve served as a barrier to the colo-ileal reflux just as the physiological valve does.