Pedro Carvalho Cassino

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 each. METHODS 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.

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 1 x 10³ 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.

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 10(5) 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.

Ischemic Postconditioning Assessment in the Liver of Rats Undergoing Mesenteric Ischemia and Reperfusion

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.

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

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

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.

Potencial of different hydroxyapatites as biomaterials in the bone remodeling

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.

DIFERENÇAS ENTRE POLIDIOXANONA E POLIGLACTINA EM ANASTOMOSES INTESTINAIS

Objetivo: Avaliar os efeitos do 5-ASA no conteúdo tecidual de mucinas num modelo experimental de CE. Método: Foram submetidos à derivação do trânsito intestinal por meio de colostomia proximal e fístula mucosa distal 16 ratos. Os animais foram divididos em dois grupos, com eutanásia feita em duas ou quatro semanas. Cada grupo foi subdividido em grupo controle com intervenção diária com soro fisiológico (SF) e experimental com 5-ASA na concentração de 1 g/mL/dia. Usaram-se os testes de Mann-Whitney e Kruskal-Wallis para análise dos resultados, adotou-se nível de significância de 5% (p ≤ 0,05). Resultado: Houve aumento do conteúdo tecidual dos diferentes tipos de mucinas nos animais submetidos à intervenção com 5-ASA, em relação aos do grupo controle. Os níveis de MUC-2 aumentaram naqueles submetidos à intervenção com 5-ASA independentemente do tempo de intervenção (duas semanas p = 0,001; quatro semanas p = 0,01). O mesmo foi observado para mucinas neutras (duas semanas p = 0,0003; quatro semanas p = 0,0001), mucinas ácidas (duas semanas p = 0,0005; quatro semanas p = 0,005) e sialomucinas (duas semanas p = 0,05). Conclusões: Clisteres com 5-ASA aumentam o conteúdo tecidual de mucinas em segmentos cólicos desprovidos de trânsito fecal em modelo experimental de CE.

Pulmonary oxidative stress in diabetic rats exposed to hyperoxia

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.

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

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.