Analysis of the biocompatibility of a biocelulose and a poly L- lactic acid membrane

The use of selective barriers as resorbable membranes has become a routine clinical procedure for guided bone regeneration. Therefore, the production of membranes with a low inflammatory potential during their resorption process has become the goal of a considerable number of researches. Aim: The purpose of the present study was to evaluate the biocompatibility of poly (L- lactic acid) (PLLA) and biocelulose membranes (BC) inserted in the subcutaneous tissue on the dorsum of rats. Methods: Fifteen animals underwent surgical procedures for the insertion of 4 types of membranes: COL (Collagen membrane) ­ Control Group; BC (Biocellulose membrane); BCAg (Biocellulose membrane impregnated with Silver); PLLA (Poly (L-lactic acid) membrane). All membrane types were inserted into each animal. Animals were euthanized after 3, 7, and 15 days of the surgical procedure. Descriptive histological analyses were carried out to investigate host tissue reaction to membrane presence by assessing the anti-inflammatory process composition associated with the membrane resorption and the presence of foreign-body reaction or encapsulation. Results: The BC membranes showed a higher degree of inflammation and poor pattern of integration with the surrounding tissues than the PLLA and COL membranes. Conclusion: The PLLA and COL membranes present better biocompatibility than the BC membranes

Experimental implantation of an arterial substitute made of silicone reinforced with polyester fabric in rabbits

OBJECTIVES: The aim of this study was to analyze silicone tubes with an internal diameter of 4 mm as a possible material for vascular prostheses. METHODS: Grafts were implanted into the infrarenal aortas of 33 rabbits. Fluoroscopic examinations were performed within 150 days after surgical implantation. Sample grafts were analyzed via electron microscopy to evaluate the eventual endothelialization of the prostheses. RESULTS: The patency rates of the prostheses were 87% (±6.7%) after 30 days, 73% (±9.3%) after 60 days and 48% (±12%) after 120 days. The material presented characteristics that support surgical implantation: good tolerance promoted by polyester tear reinforcement, ease of postoperative removal and a lack of pseudoaneurysms. However, intimal hyperplasia was a limiting factor for the patency rate. CONCLUSIONS: We concluded that polydimethylsiloxane has limited potential as an alternative material for small vascular prostheses.

Growth kinetics, effect of carbon substrate in biosynthesis of mcl-PHA by Pseudomonas putida Bet001

Growth associated biosynthesis of medium chain length poly-3-hydroxyalkanoates (mcl-PHA) in Pseudomonas putida Bet001 isolated from palm oil mill effluent was studied. Models with substrate inhibition terms described well the kinetics of its growth. Selected fatty acids (C8:0 to C18:1) and ammonium were used as carbon and nitrogen sources during growth and PHA biosynthesis, resulting in PHA accumulation of about 50 to 69% (w/w) and PHA yields ranging from 10.12 g L-1 to 15.45 g L-1, respectively. The monomer composition of the PHA ranges from C4 to C14, and was strongly influenced by the type of carbon substrate fed. Interestingly, an odd carbon chain length (C7) monomer was also detected when C18:1 was fed. Polymer showed melting temperature (Tm) of 42.0 (± 0.2) °C, glass transition temperature (Tg) of -1.0 (± 0.2) °C and endothermic melting enthalpy of fusion (ΔHf) of 110.3 (± 0.1) J g-1. The molecular weight (Mw) range of the polymer was relatively narrow between 55 to 77 kDa.

Estudo experimental comparativo de remendos arteriais de polidimetilsiloxano com reforço de tecido de poliéster (PDMSr) versus politetrafluoretileno expandido (PTFEe) em aorta de coelhos / Patch of polydimethylsiloxane reinforced with polyester fabric for aortic angioplasty in rabbits

Introdução: Apesar de bons resultados descritos na literatura, o substituto ideal para a utilização como remendo no fechamento arterial ainda não existe. Por este motivo, ainda há espaço para a busca por remendo que seja biocompatível, e que apresente facilidade de manuseio e resultados satisfatórios. Avaliamos remendos arteriais de silicone (polidimetilsiloxano com reforço em poliéster - PDMSr) em comparação com remendos arteriais de PTFEe. Objetivo: O objetivo deste trabalho é comparar, em modelo experimental, em coelhos, os resultados de remendos arteriais feitos em PDMSr com remendos de PTFEe. Materiais e Método: A amostra foi definida em 10 animais que completassem todas as etapas da pesquisa em cada grupo. Os animais foram submetidos à laparotomia mediana e abertura longitudinal da aorta de aproximadamente 8mm, realizando-se o seu fechamento com remendo do grupo selecionado, seguido do fechamento por planos. Os animais foram mantidos em biotério até o 60º PO, quando, então, realizou-se arteriografia de controle, e análise macro e microscópica de peça. Resultados: Para se atingir a amostra desejada, foram necessários 12 procedimentos no grupo PDMSr e 16 no grupo PTFEe. Ocorreram 2 óbitos no grupo PDMSr e 6 no grupo PTFEe. Apesar do número maior de óbitos no grupo PTFEe não houve diferença estatística na sobrevida entre os grupos. Um animal do grupo PDMSr apresentou monoparesia em pata posterior direita e um animal do grupo PTFEe apresentou hérnia incisional. Não houve diferença estatística nas complicações entre os grupos. O tempo operatório foi estatisticamente maior no grupo PTFEe quando comparamos todos os animais, fato que não se repetiu quando excluímos os animais que faleceram...

Introduction: Although good results are reported for various materials for use as patches for arterial closure, as yet none of these is ideal. Therefore, research is continuing into development of a patch that is biocompatible and provides ease of handling, while having satisfactory outcomes. A new silicone arterial patch (polydimethylsiloxane reinforced with polyester fabric, PDMSr) was compared with patches made of expanded polytetrafluoroethylene (ePTFE). Objective: To compare the outcomes between arterial patches made of PDMSr with those made of ePTFE, in an experimental rabbit model. Materials and Method: Rabbits were placed in two groups, and received either PDMSr or ePTFE arterial patches (PDMSr group and ePTFE group, respectively). The animals underwent laparotomy and longitudinal opening of the aorta, which was then closed with the selected patch, followed by suture of all layers. The animals were kept in their cages until the 60th postoperative day, when arteriography, removal of the aorta, and macroscopic and optic and scanning electron microscopic analyzes of the aorta were performed. Ten rabbits from each group that had completed all stages of the research were included in analyses. Results: Twelve procedures were performed in the PDMSr group and 16 in the ePTFE group. There were 2 deaths in the PDMSr group and 6 in the ePTFE group. Despite the higher number of deaths in the ePTFE group, there was no statistical difference in survival rate between the groups. One animal in the PDMSr group developed monoparesis in its right hind paw and 1 animal in the ePTFE group had an incisional hernia. There was no statistical difference in complications between the groups. The operative time was significantly longer in the ePTFE group when all animals were included in analysis, but not when animals that died were excluded...

Comparative study between meshes of polyester with collagen and polytetrafluoroethylene in the repair of defects produced in abdominal wall of rats / Estudo comparativo entre as telas de poliéster com colágeno e politetrafluoretileno no reparo de defeitos produzidos na parede abdominal de ratos

PURPOSE: To study the intraperitoneal use of polyester with collagen and polytetrafluoroethylene meshes in the correction of total ventral wall defects in rats. METHODS: Thirty two rats were evaluated and divided randomly into four groups and underwent laparotomy and preparation of total defects of the abdominal wall. Next, the correction of the defect with the intraperitoneal placement of the chosen mesh was performed. The rats were submitted to euthanasia at 30 and 90 days after surgery. Were analyzed the macroscopic adhesions and microscopic aspects, and applied stress rupture test RESULTS: All animals showed intraperitoneal adhesions in varying degrees, with no statistical significance difference. There was no difference also between groups in the evaluation of stress rupture tests. On the microscopic aspect, the A30 group had less inflammatory reaction and less formation of granulomas and foreign body reaction that the B30 group, with significant difference. CONCLUSIONS: There was no difference in intraperitoneal adhesion and tensile rupture strength among groups. Group B30 presented granulomatous inflammatory reaction at the site of mesh attachment to the wall significantly higher than the A30.

OBJETIVO: Estudar comparativamente o uso intraperitoneal das telas de poliéster com colágeno e politetrafluoretileno na correção de defeitos totais da parede ventral em ratos. MÉTODOS: Foram avaliados 32 ratos distribuídos em quatro grupos aleatórios e submetidos à laparotomia e confecção de defeitos totais da parede abdominal. Em seguida, foi realizada a correção do defeito com a colocação intraperitoneal das telas. A eutanásia ocorreu aos 30 e 90 dias do pós-operatório. Foram analisadas as aderências macroscópicas, aspectos microscópicos e aplicado teste de tensão de ruptura. RESULTADOS: Todos os animais apresentaram aderências abdominais intraperitoneais em vários graus, sem significância estatística. Não houve diferença entre os grupos na avaliação dos testes de tensão de ruptura. Na análise microscópica o grupo A30 teve menor reação inflamatória e formação de granulomas, e menor reação do tipo corpo estranho quando comparado ao grupo B30, com resultados significativos. CONCLUSÕES: Não houve diferença significativa entre os grupos tanto em relação à formação de aderências intraperitoneais quanto à tensão de ruptura. O grupo B30 apresentou reação inflamatória e formação granulomatosa no local de fixação na parede significativamente maior que o grupo A30.