Potencial of different hydroxyapatites as biomaterials in the bone remodeling

Abstract Purpose: To analyze the therapeutic potentials of different hydroxyapatites used for the correction of bone defects in rats. Methods: Forty rats, male, albino wistar, were distributed in 4 groups. They were submitted to a 3.5 mm defect in tibia. They received low purity hydroxyapatite, Strontium hydroxyapatite and hydroxyapatite doped with gallium, having a seven day evaluation time. Histopathology slides were stained with hematoxylin-eosin, for morphological evaluation. Were analyzed inflammatory processes, necrosis, presence of osteoclasts and osteoblasts, presence of the material, presence of white cells, neovascularization and bone neoformation. Results: It was observed that the groups HAPSr and HAPGa, presented better results of trabecular bone, hyaline cartilage and bone marrow more organized. Conclusion: There was improvement in the repair of the bone defect produced, showing that these hydroxyapatites are effective osteoinductive, osteoconductive, osteintegrant agents and have biocompatibility, and may be indicated for use in defect repairs.

Differences between polydioxanone and poliglactin in intestinal anastomoses - a comparative study of intestinal anastomoses / Diferenças entre polidioxanona e poliglactina em anastomoses intestinais - estudo comparativo de anastomoses intestinais

ABSTRACT Introduction: Intestinal anastomosis is a surgical practice constantly realized by surgeons worldwide. When the option is to perform manual anastomosis, which is still widely used for its low cost, the question arises as to the best material to be applied. Objective: To compare polydioxanone and polyglactin threads for healing and tensile strength in intestinal anastomosis in rats. Method: We used 25 rats Wistar; after anesthesia, in groups A and B (10 rats each), laparotomy was performed, transection of the ileum at 5 and 10 cm proximally to the ileocecal valve; in group A, anastomosis was performed with 4 separate extra mucosal sutures with polidioxanone; in group B, anastomosis was performed with polyglactin; in group C (5 rats), laparotomy and manipulation of the ileum were performed. After 21 days, the animals were anesthetized and submitted to euthanasia. The specimens were sent for histopathological study and tensile strength analysis. Statistical analysis was performed using the Turkey and Student's t tests, with a significance of p < 0.05. Results: The results showed that in the tensile strength analysis, there were no significant differences between them. The histological analysis showed significant differences between the cicatrization pattern, where polydioxanone caused less fibrosis than polyglactin. Conclusion: Polydioxanone caused less fibrosis than polyglactin in intestinal anastomoses of rats.

RESUMO Introdução: Anastomose intestinal é uma prática cirúrgica constantemente realizada pelos cirurgiões em todo o mundo. Quando a opção é a anastomose manual - um procedimento ainda amplamente empregado, graças a seu baixo custo - coloca-se o problema de saber qual é o melhor material a ser aplicado. Objetivo: Comparar fios de polidioxanona e poliglactina quanto à cicatrização e resistência à tração em anastomoses intestinais em ratos. Método: Utilizamos 25 ratos Wistar; depois da anestesia, foi realizada laparotomia nos grupos A e B (10 ratos cada), com transecção do íleo a 5 e 10 centímetros proximalmente à válvula ileocecal; no grupo A, a anastomose foi realizada com 4 suturas de mucosa separadas com uso de polidioxanona; no grupo B, a anastomose foi realizada com poliglactina; no grupo C (5 ratos), foi realizada apenas a laparotomia e manipulação do íleo. Transcorridos 21 dias, os ratos foram anestesiados e submetidos à eutanásia. Os espécimes foram enviados para estudo histopatológico e análise de resistência à tração. A análise estatística foi efetuada com a aplicação dos testes de Tukey e de t de Student, com significância de p < 0,05. Resultados: Os resultados demonstraram que, na análise de resistência à tração, não foram observadas diferenças significativas entre os materiais. A análise histológica revelou diferenças significativas entre padrões de cicatrização, em que polidioxanona causou menos fibrose versus poliglactina. Conclusão: Polidioxanona causou menos fibrose versus poliglactina em anastomoses intestinais realizadas em ratos.

Pulmonary oxidative stress in diabetic rats exposed to hyperoxia

Abstract Purpose: To evaluate the pulmonary oxidative stress in diabetic rats exposed to hyperoxia for 90 minutes. Methods: Forty male Wistar rats were divided into four groups, each one containing 10 animals, according to the oxygen concentration to which they were exposed: 21%, 50%, 75% and 100% (hyperoxia). In each group five animals were randomly induced to diabetes by means of at a dose of 55 mg/kg of streptozotocin (STZ). Results: Seventy two hours after diabetes induction, a significant difference was seen in blood glucose in the experimental groups in comparison with the control. In the experimental groups a significant difference was observed in the concentration of malondialdehyde (MDA) in lung tissue and blood plasma (p<0.05), except the 50% group. In the control group, significant differences in the MDA concentration in plasma and lung tissue were also observed (p<0.05), except the 75% group. The MDA concentration in lung tissue in comparison with the diabetic and non-diabetic groups showed a significant difference in the 21% group; however, no difference was seen in the 75 and 100% groups. Conclusion: In diabetic animals high oxygen concentrations (75 and 100%) do not appear to exert deleterious effects on lipid peroxidation in lung tissue.

Ischemic postconditioning assessment in the liver of rats undergoing mesenteric ischemia and reperfusion

Abstract Introduction: Ischemic postconditioning is a method that shows evidence of efficacy in minimizing reperfusion injury; however, its effectiveness in preventing injuries in distant organs is still unknown, especially in those who have undergone mesenteric ischemia and reperfusion. Objective: To evaluate the effect of ischemic postconditioning in preventing reperfusion injury in the liver of rats submitted to mesenteric ischemia and reperfusion, comparing two different methods of ischemic postconditioning. Methods: 30 Wistar male rats were used, distributed into three groups: Group A: Ten rats submitted to intestinal ischemia for 30 minutes followed by reperfusion for 60 minutes; Group B: Ten rats subjected to ischemia and reperfusion; after ischemia, two cycles of reperfusion (two minutes each) interleaved with two cycles of ischemia (two minutes each); and Group C: Ten rats subjected to ischemia and reperfusion; after ischemia, four cycles of reperfusion (30 seconds each) interspersed with four cycles of ischemia (30 seconds each). After the experiment, the left lobe of the liver was resected for subsequent histological analysis, using the following classification: grade 1 - centrilobular congestion; grade 2 - centrilobular congestion with some degeneration of hepatocytes in one or two central veins; and grade 3 - multifocal centrilobular congestion and degeneration of portal hepatocytes. Results: The mean degree of liver damage found was 1.8 in group A, 1.7 in group B and 1.3 in group C. There was no statistically significant difference between the groups. Conclusion: Ischemic postconditioning was unable to minimize reperfusion injury in rats undergoing mesenteric ischemia and reperfusion.

Treatment of fistula-in-ano with cyanoacrylate glue with and without prior seton placement in rats

ABSTRACT PURPOSE: To evaluate the efficacy of ethyl-cyanoacrylate in the treatment of fístula-in-ano in rats with and without prior seton placement. METHODS: Thirty rats Wistar with fístula-in-ano produced surgically, distributed in three groups: group A (ethyl-cyanoacrylate) - treated by application of ethyl-cyanoacrylate into fístula tract; group B (seton + ethyl-cyanoacrylate) - seton placement followed by application of ethyl-cyanoacrylate into fístula tract, 30 days later; group C (control) - no treatment. After 60 days the animals were submited to euthanasia and the specimens were analyzed by pathologist. The results were analyzed by Chi-square test with significant value of p<0.05. RESULTS: One animal of group B died. Were found tracts fully healed: 7, 5 and 2, in groups A, B and C, respectivelly. There was a statistically significant difference between groups A and C (p=0.02). When joined all animals treated with glue (A + B) compared to group C there was also statistically significant difference (p=0.02). CONCLUSIONS: The use of ethyl-cyanoacrylate glue was effective in closing anal fistulae in rats. There was no advantage in the prior application of seton.

Importance of duration and number of ischemic postconditioning cycles in preventing reperfusion mesenteric injuries. Experimental study in rats

PURPOSE:To evaluate the effect of ischemic postconditioning(IPC) on intestinal mucosa of rats subjected to ischemia and reperfusion process comparing two cycles of reperfusion and ischemia lasting two minutes each and four cycles of reperfusion and ischemia lasting 30 seconds eachMETHODS: Thirty Wistar rats were distributed into three groups: group A (10 rats), ischemia (30 minutes) and reperfusion (60 minutes); group B (10 rats), ischemia and reperfusion plus IPC by two lasting two minutes each; and Group C (10 rats), ischemia and reperfusion plus IPC by four cycles lasting 30 seconds each. Finally, a segment of small intestine was resected for histological analysis. We analysed the results according to Chiu et al. classification and proceeded to the statistical treatment by Kruskal-Wallis test (p<0.05).RESULTS: The mean degree of tissue injury according to Chiu et al. classification were: Group A, 2.77; in group B, 1.4; and group C, 1.4. B X C (p<0.05).CONCLUSIONS: Ischemic postconditioning was able to minimize reperfusion injury of rats undergone mesenteric ischemia and reperfusion process. There was no difference in the effectiveness of the method comparing two cycles of two minutes with four cycles of 30 seconds by H&E histological evaluation of the ileum after 60-minute reperfusion.

Evaluation of Pulmonary Reperfusion Injury in Rats Undergoing Mesenteric Ischemia and Reperfusion and Protective Effect of Postconditioning on this Process

ABSTRACT INTRODUCTION: Some publications have demonstrated the presence of lung reperfusion injury in mesenteric ischemia and reperfusion (I/R), but under to diverse methods. Postconditioning has been recognized as effective in preventing reperfusion injury in various organs and tissues. However, its effectiveness has not been evaluated in the prevention of lung reperfusion injury after mesenteric ischemia and reperfusion. OBJECTIVE: To evaluate the presence of pulmonary reperfusion injury and the protective effect of ischemic postconditioning on lung parenchyma in rats submitted to mesenteric ischemia and reperfusion. METHODS: Thirty Wistar rats were distributed into three groups: group A (10 rats), which was held mesenteric ischemia (30 minutes) and reperfusion (60 minutes); group B (10 rats), ischemia and reperfusion, interspersed by postconditioning with two alternating cycles of reperfusion and reocclusion, for two minutes each; and group C (10 rats), ischemia and reperfusion interleaved by postconditioning with four alternating cycles of reperfusion and reocclusion of 30 seconds each. Finally, it was resected the upper lung lobe for histological analysis. RESULTS: There were mild lung lesions (grade 1) in all samples. There was no statistical difference between groups 1 and 2 (P >0.05). CONCLUSION: The mesenteric ischemia and reperfusion in rats for thirty and sixty minutes, respectively, caused mild reperfusion injury in lung. Postconditioning was not able to minimize the remote reperfusion injury and there was no difference comparing two cycles of two minutes with four cycles of 30 seconds.

Very short cycles of postconditioning have no protective effect against reperfusion injury. Experimental study in rats / Ciclos muito curtos de pós-condicionamento não protegem contra lesão de reperfusão. Estudo experimental em ratos

Introduction: Ischemic postconditioning has been recognized as effective in the prevention of reperfusion injury in situations of ischemia and reperfusion in various organs and tissues. However, it remains unclear what would be the best way to accomplish it, since studies show great variation in the method of their application. Objective: To assess the protective effect of ischemic postconditioning on ischemia and reperfusion in rats undergoing five alternating cycles of reperfusion and ischemia of 30 seconds each one. Methods: We studied 25 Wistar rats distributed in three groups: group A (10 rats), which underwent mesenteric ischemia (30 minutes) and reperfusion (60 minutes); Group B (10 rats), undergoing ischemia (30 minutes) and reperfusion (60 minutes), intercalated by postconditioning (5 alternating cycles of reperfusion and ischemia of 30 seconds each one); and group C - SHAM (5 rats), undergoing only laparotomy and manipulation of mesenteric artery. All animals underwent resection of an ileum segment for histological analysis. Results: The mean lesions degree according to Chiu et al. were: group A, 2.77, group B, 2.67 and group C, 0.12. There was no difference between groups A and B (P>0.05). Conclusion: Ischemic postconditioning was not able to minimize or prevent the intestinal tissue injury in rats undergoing ischemia and reperfusion process when used five cycles lasting 30 seconds each one. .

Introdução: O pós-condicionamento isquêmico tem sido reconhecido como eficaz na prevenção das lesões de reperfusão em situações de isquemia e reperfusão em vários órgãos e tecidos. Entretanto, não está ainda claro qual seria a melhor maneira de realizá-lo, já que as publicações mostram grande variação de método no seu emprego. Objetivo: Avaliar o efeito protetor do pós-condicionamento isquêmico na isquemia e reperfusão intestinal em ratos, através de cinco ciclos alternados de 30 segundos de isquemia e 30 segundos de reperfusão. Métodos: Foram estudados 25 ratos Wistar, distribuídos em três grupos: grupo A (10 ratos), em que se realizou isquemia (30 minutos) e reperfusão (60 minutos) mesentérica; grupo B (10 ratos), isquemia e reperfusão, seguidos de pós-condicionamento isquêmico com 5 ciclos alternados de reperfusão e reoclusão, de 30 segundos cada; e grupo C (5 ratos), controle (SHAM). Ao final, ressecou-se um segmento do intestino delgado para análise histológica. Avaliaram-se os resultados pela classificação de Chiu et al. e procedeu-se ao tratamento estatístico. Resultados: As médias dos graus de lesão tecidual segundo a classificação de Chiu et al. foram: no grupo A, 2,77; no grupo B, 2,67; e no grupo C, 0,12. A diferença entre o resultado do grupo A com o resultado do grupo B não teve significância estatística (P>0,05). Conclusão: O pós-condicionamento isquêmico não foi capaz de minimizar ou prevenir a lesão tecidual intestinal de ratos submetidos ao processo de isquemia e reperfusão mesentérica quando utilizados cinco ciclos com duração de 30 segundos cada. .

Histopathological evaluation of tumor necrosis and volume after cyanogenic chemotherapy

PURPOSE: To determine the percentage of tumoral necrosis and volume after cyanogenic chemotherapy. METHODS: Histopathological findings of 20 Swiss mice inoculated subcutaneously in the left abdominal wall with 0.05 ml of cell suspension containing 2.5 x 105 viable cells of the Ehrlich tumor were evaluated. The tumor response to cyanogenic chemotherapy was determined using a system that comprises two inhibition factors of tumor growth by calculating the percentage of necrosis in the tumor tissue and calculation of tumor volume in treated animals relative to that in control animals. The importance of this system has been validated by the correlation between tumor inhibition in the groups treated with the respective percentages of necrosis. RESULTS: While the control group presented an average of 13.48 ± 14.71% necrosis and average tumor volume of 16.18 ± 10.94, the treated group had an average of 42.02 ± 11.58 and 6.8 ± 3.57, respectively. The tumor inhibition was significantly associated with treatment (p=0.0189). The analysis of necrosis percentage showed a significant prognostic importance (p=0.0001). CONCLUSION: It is concluded that the effect of cyanogenic chemotherapy showed strong inhibitory action of tumor growth, as well as an increase in its area of necrosis. .

Sulfane sulfur deficiency in malignant cells, increasing the inhibiting action of acetone cyanohydrin in tumor growth

PURPOSE: To demonstrate the irreversible poisoning action of the acetone cyanohydrin (AC) in malignant cells. METHODS: Thirty male Swiss mice were inoculated with 1x10³ Ehrlich tumor (ET) cells. The mice were divided into three groups (n=10): CG (saline); ACG1 (1.864 mg/Kg of AC) and ACG2 (2.796 mg/Kg of AC), treated every 48 hours from day 3 until day 13. On day 15 the mice were euthanized and the number of viable cells in ascites was determined. In the meantime, ET cells were incubated with AC (0.5, 1.0, 2.0 μg/mL). Cell viability and percentage of growth inhibition (PGI) were checked after one, two, three, four, 18 and 24 hours. RESULTS: There was reduction in volume and number of viable cells in ACG1 and ACG2 compared to CG. In ACG1 one of the animals did not present ascites. In ACG2 two mice did not present ascites and in CG none of the mice present ascites. The action of AC was dose and time dependent and there was no significant difference among the three doses. CONCLUSION: The acetone cyanohydrin promoted reduction of the tumor and also prevented tumor development in 20% of the treated animals.

Experimental model of anal fistula in rats / Modelo experimental de fistula anal em ratos

INTRODUCTION: the management of anal fistula remains debatable. The lack of a standard treatment free of complications stimulates the development of new options. OBJECTIVE: to develop an experimental model of anal fistula in rats. METHODS: to surgically create an anal fistula in 10 rats with Seton introduced through the anal sphincter musculature. The animals were euthanized for histological fistula tract assessment. RESULTS: all ten specimens histologically assessed had a lumen and surrounding granulation tissue. There was complete epithelialization of the tract in two samples, halfway epithelialization in one sample and epithelialization of only the outer portion in six samples. Epithelialization was not evident in one tract. CONCLUSION: anal fistulas in rats were histologically proved. (AU)

INTRODUÇÃO: o manejo da fístula anal ainda permanece um debate. A ausência de um tratamento ideal isento de complicações estimula o desenvolvimento de novas modalidades terapêuticas. OBJETIVO: desenvolver um modelo experimental de fístula anal em ratos. METODOLOGIA: criação de fístula anal cirúrgica em 10 ratos por meio de passagem de fio de aço através da musculatura do esfíncter anal. Os animais foram submetidos a eutanásia para comprovação histológica do trajeto fistuloso. RESULTADOS: todos os segmentos analisados histologicamente apresentaram lúmen e tecido de granulação. Houve epitelização completa do trajeto em dois espécimes, epitelização até a metade do trajeto em um, e epitelização somente da porção externa em seis. Um trajeto não apresentou área de epitelização. CONCLUSÃO: o desenvolvimento de fístula anal em ratos foi comprovado histologicamente. (AU)