Comparative study of four different types of intraperitoneal mesh prostheses in rats

Abstract Purpose: To compare four types of mesh regarding visceral adhesions, inflammatory response and incorporation. Methods: Sixty Wistar rats were divided into four groups, with different meshes implanted intraperitoneally: polytetrafluoroethylene (ePTFE group); polypropylene with polydioxanone and oxidized cellulose (PCD); polypropylene (PM) and polypropylene with silicone (PMS). The variables analyzed were: area covered by adhesions, incorporation of the mesh and inflammatory reaction (evaluated histologically and by COX2 immunochemistry). Results: The PMS group had the lowest adhesion area (63.1%) and grade 1 adhesions. The ePTFE and PM groups presented almost the total area of their surface covered by adherences (99.8% and 97.7% respectively) The group ePTFE had the highest percentage of area without incorporation (42%; p <0.001) with no difference between the other meshes. The PMS group had the best incorporation rate. And the histological analysis revealed that the inflammation scores were significantly different. Conclusions: The PM mesh had higher density of adherences, larger area of adherences, adherences to organs and percentage of incorporation. ePTFE had the higher area of adherences and lower incorporation. The PMS mesh performed best in the inflammation score, had a higher incorporation and lower area of adherences, and it was considered the best type of mesh.

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.

Treatment of Malignant Biliary Obstruction with a PTFE-Covered Self-Expandable Nitinol Stent

OBJECTIVE: We wanted to determine the technical and clinical efficacy of using a PTFE-covered self-expandable nitinol stent for the palliative treatment of malignant biliary obstruction. MATERIALS AND METHODS: Thirty-seven patients with common bile duct strictures caused by malignant disease were treated by placing a total of 37 nitinol PTFE stents. These stents were covered with PTFE with the exception of the last 5 mm at each end; the stent had an unconstrained diameter of 10 mm and a total length of 50-80 mm. The patient survival rate and stent patency rate were calculated by performing Kaplan-Meier survival analysis. The bilirubin, serum amylase and lipase levels before and after stent placement were measured and then compared using a Wilcoxon signed-rank test. The average follow-up duration was 27.9 weeks (range: 2-81 weeks). RESULTS: Placement was successful in all cases. Seventy-six percent of the patients (28/37) experienced adequate palliative drainage for the remainder of their lives. There were no immediate complications. Three patients demonstrated stent sludge occlusion that required PTBD (percutaneous transhepatic biliary drainage) irrigation. Two patients experienced delayed stent migration with stone formation at 7 and 27 weeks of follow-up, respectively. Stent insertion resulted in acute elevations of the amylase and lipase levels one day after stent insertion in 11 patients in spite of performing endoscopic sphincterotomy (4/6). The bilirubin levels were significantly reduced one week after stent insertion (p < 0.01). The 30-day mortality rate was 8% (3/37), and the survival rates were 49% and 27% at 20 and 50 weeks, respectively. The primary stent patency rates were 85%, and 78% at 20 and 50 weeks, respectively. CONCLUSION: The PTFE-covered self-expandable nitinol stent is safe to use with acceptable complication rates. This study is similar to the previous studies with regard to comparing the patency rates and survival rates.

Estudo comparativo da inflamação tecidual causada por diferentes fios de sutura na gengiva humana / Comparative study of human gingival tissue reaction to different suture materials

Introdução - As suturas têm um papel importante na maioria das cirurgias, podendo influenciar grandemente no resultado clínico final. A escolha do fio de sutura constitui-se em um dos fundamentos para se obter a menor reação inflamatória tecidual quando do processo de reparação, já que alguns fios são considerados inertes, provocando menor reação do que outros. Materiais e Métodos - Foram utilizados quatro diferentes fios de sutura, a saber : seda, nylon, poliglactina 910 (Vicryl) e politetrafluoretileno expandido (e-PTFE). Os fios de sutura foram colocados em gengivas humanas as quais seriam submetidas a cirurgias pré-protéticas. Após sete dias, o tecido gengival foi excisado e processado histologicamente para observação em microscopia óptica. Resultados e Conclusão - Os resultados permitiram chegar à conclusão que o fio que promoveu menor reação foi o de poliglactina, seguido pelos de e-PTFE e nylon, culminando com a seda que provocou maior inflamação.

Introduction - The sutures play an important role in most of the surgeries, and may greatly influence the final clinical result. The choice of the suture material consists of one of the basis to obtain the least tissular inflammatory reaction at the time of healing process, since some materials are considered inert promoting less reaction than others. Materials and Method - It was evaluated the gingival reaction using four different suture materials such as: silk, nylon, polyglactin 910 (Vicryl) and expanded polytetrafluorethylene (e-PTFE). The suture materials were placed in human gingiva that would be to preprosthetics surgeries. After seven days, the gingival tissue was excised and histologically processed for optical microscopy. Results and Conclusion - The results show that the suture which promoted the least reaction was the polyglactin, followed by e-PTFE, nylon and silk which promoted the highest inflammation.

Calcification Comparison of Polymers for Vascular Graft

Polytetrafluoroethylene (PTFE), polyurethane (PU) and silicone are widely known biocompatible polymers which are commonly used for vascular grafts. However, in vitro and in vivo calcifications of these polymers have been found to seriously compromise their quality as biomaterials. In consideration of this problem, the present study compared the calcification rate and extent of PTFE, PU and silicone. Using the in vitro flow-type method, PTFE, PU and silicone films were tested for 1, 4, 7, 10, 14 and 21 days. After 21 days of in vitro calcification test, the calcium levels on PTFE, PU and silicone were 35.89 5.01 microgram /cm2, 23.73 0.68 microgram/cm2 and 19.86 5.28 microgram/cm2, respectively. The higher observed calcium level for PTFE may be due to the effect of the rough surface of PTFE in accumulating calcium ions on the polymer surface. From the 7th day of test, the [Ca]/[P] molar ratio started to decrease over time, and PTFE showed a faster calcification process. This decreasing [Ca]/[P] molar ratio demonstrated the typical calcification mechanism consisting of phosphorus ion accumulation following calcium ion accumulation. This study concluded that PU and silicone are less calcified than PTFE film, a finding in good agreement with previously published studies.

Efeitos da tela de politetrafluoroetileno expandido colocada no espaço pré-peritoneal por videolaparoscopia em suínos / Efects of expanded polytetrafluorethylene (e-PTFE) mesh, in the preperitoneal space introduced by videolaparoscopy in pigs

Com o objetivo de observar os efeitos produzidos pela tela de politetrafluoroetileno expandido (PTFE-e), no espaço pré-peritoneal, foram utilizados 20 suínos (n=20) da raça Large White, todos machos, distribuídos em dois grupos de dez animais. A técnica operatória utilizada foi a videolaparoscopia transabdominal. De um lado, na regiao inguinal, o espaço pré-peritoneal foi dissecado e a tela fixada; na regiao contralateral, o procedimento foi o mesmo, sem a colocaçao da tela, servindo como controle. O peritônio parietal local foi aproximado com uma sutura contínua de poliglactina 910. A eutanásia foi realizada aos sete e vinte um dias de pós-operatório. No primeiro grupo, um animal apresentou aderência no local de implantaçao da tela e, no segundo grupo, um animal também apresentou aderência, mas no lado controle. Concluiu-se, baseado na presente pesquisa, que a tela de PTFE-e nao provocou a formaçao de aderências, quando colocada no espaço pré-peritoneal em suínos.

Estudo comparativo das reaçöes teciduais a implantaçäo de silicone e politetrafluoroetileno no dorso de ratos / Comparative study of the tecidual reactions of silicone and expanded polietrafluoroetilene implanted at back of the rats

A importância das biopóteses na medicina abrange diversas áreas cirúrgicas. Com o objetivo de comparar a reaçäo tecidual do implante de silicone, um dos mais utilizados, com o implante de politetrafluoroetileno expandido (PTFE-E), de uso mais recente, nos propusemos a realizar este estudo. Foram utilizados trinta ratos (Rattus norvegicus albinus) machos, distribuidos em três grupos iguais, com implantes de fragmento discóides dos materiais citados, no dorso de cada rato. Os grupos diferiram entre si quanto ao período de eutanásia: três, sete e trinta dias. Com base no modelo experimental e utilizando metodologia morfométrica, do ponto de vista histológico näo houve reaçäo inflamatória aguda importante que se pudesse correlacionar aos meteriais de implantes. A proliferaçäo vascular e a presença de fibrose foram prolongadas em relaçäo à cicatrizaçäo normal. A irregularidade do PTFE-E, provavelmente relaciona-se à maior quantidade de vasos e de fibrose tardia constatada neste material, quando comparado ao implante de silicone

Uso do PTFE (Gore-Tex) para tratamento da blefaroptose severa / The use of PTFE (Gore-tex) for severe blepharoptosis

Nesse estudo relatamos a experiência e complicaçöes com o uso do plitetrafluoroetileno (Gore-Tex), na realizaçäo de suspensäo ao frontal em 19 pacientes com ptose palpebral severa. A complicaçäo mais comum foi a formaçäo de granuloma de corpo estranho

Evaluation of the thrombogenecity of microvascular prosthesis by in vivo microscopy

Expanded polytetrafluoroethylene(ePTFE) grafts 4mm long and 1mm in diameter were implanted into the iliac artery of 100-150g male rats using standard microvascular technique. Prior to clamp removal, the cremaster muscle was isolated as an island flap based on the iliac artery and observed using intravital fluorescence microscopy. Fields which contained a bifurcation of a first order arteriole(80-100 microns diameter) into second order arteriole(50-80 microns) were chosen for observation. Platelets were labeled in vivo with acridine red to visualize and quantify the aggregates. Images of microemboli were counted manually and the area was measured by computerized planimetry. Six control grafts were implanted with no further processing, six were irrigated with heparin, and six were coated with tridodecylmethylammonium chloride(TDMAC) and heparin. Most thrombi appeared within the first five minutes after implantation in all groups. The total number of emboli observed in the control group was 91 pr animal, in the heparin irrigation group it was 84, and in the TDMAC-heparin group it was 22. The total thrombus area observed per animal was 137,660 +/- 29,467 microns 2 in the control group, 79,040 +/- 10,893 microns 2 in the heparin irrigation group, and 17,498 +/- 6,059 microns 2 in the TDMAC-heparin group (p<.01 vs control or heparin irrigation group). With this results we could find that heparin irrigation and TDMAC-heparin coating appear to reduce the number, size, and total amount of microemboli generated by ePTFE graft implantation and apparent thromboresistant property of TDMAC-heparin coating may have widespread application in many clinical and research areas and this experimental model can be used for evaluation of other graft matrials.

Side effects of polytef in experimental fetal surgery

The possible side effects of particles of polytef paste, a sterile mixture of polytetrafluoroethylene, glycerin, and polysorbate on rapidly growing fetal tissue, were investigated as the first part of a three-stage study designed to investigate the effects on the renal cortex of the periureteric injection of polytef, as used in the treatment of severe vesicoureteric reflux. Eighteen New Zealandar fetal rabbits were injected with polytef and 8 were injected with normal saline as a control. The group injected with polytef had a 20% maternal death rate, 100% fetal loss and a high rate of fetal growth failure. Prematurity. examination of two rabbits that died before delivery, did not reveal any fetal tissue in the uterus, nor did examination of the uterus from 1 surviving rabbit that did not deliver. However, all the fetal rabbits injected with saline had normal birth weights; there was no fetal loss or prematurm Surgeons using polytef paste should be aware of its effects on rapidly growing fetuses