ALESSANDRO RODRIGO BELON
Projetos de Pesquisa
Unidades Organizacionais
LIM/26 - Laboratório de Pesquisa em Cirurgia Experimental, Hospital das Clínicas, Faculdade de Medicina
10 resultados
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- Impact of Three Methods of Ischemic Preconditioning on Ischemia-Reperfusion Injury in a Pig Model of Liver Transplantation(2022) BELON, Alessandro Rodrigo; TANNURI, Ana Cristina Aoun; MOREIRA, Daniel de Albuquerque Rangel; FIGUEIREDO, Jose Luiz; SILVA, Alessandra Matheus da; SERAFINI, Suellen; GUIMARAES, Raimundo Renato; FARIA, Caroline Silverio; ALEXANDRE, Alcione Sanches de; GONCALVES, Josiane Oliveira; PAES, Vitor Ribeiro; TANNURI, UenisBackground Ischemic preconditioning (IPC), either direct (DIPC) or remote (RIPC), is a procedure aimed at reducing the harmful effects of ischemia-reperfusion (I/R) injury. Objectives To assess the local and systemic effects of DIPC, RIPC, and both combined, in the pig liver transplant model. Materials and methods Twenty-four pigs underwent orthotopic liver transplantation and were divided into 4 groups: control, direct donor preconditioning, indirect preconditioning at the recipient, and direct donor with indirect recipient preconditioning. The recorded parameters were: donor and recipient weight, graft-to-recipient weight ratio (GRWR), surgery time, warm and cold ischemia time, and intraoperative hemodynamic values. Blood samples were collected before native liver removal (BL) and at 0 h, 1 h, 3 h, 6 h, 12 h, 18 h, and 24 h post-reperfusion for the biochemical tests: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), creatinine, BUN (blood urea nitrogen), lactate, total and direct bilirubin. Histopathological examination of liver, gut, kidney, and lung fragments were performed, as well as molecular analyses for expression of the apoptosis-related BAX (pro-apoptotic) and Bcl-XL (anti-apoptotic) genes, eNOS (endothelial nitric oxide synthase) gene, and IL-6 gene related to inflammatory ischemia-reperfusion injury, using real-time polymerase chain reaction (RT-PCR). Results There were no differences between the groups regarding biochemical and histopathological parameters. We found a reduced ratio between the expression of the BAX gene and Bcl-XL in the livers of animals with IPC versus the control group. Conclusions DIPC, RIPC or a combination of both, produce beneficial effects at the molecular level without biochemical or histological changes.
- Estimation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension(2021) JENG, Brasil Chian Ping; ANDRADE, Almir Ferreira de; BRASIL, Sergio; BOR-SENG-SHU, Edson; BELON, Alessandro Rodrigo; ROBERTIS, Maira; DE-LIMA-OLIVEIRA, Marcelo; RUBIANO, Andres Mariano; GODOY, Daniel Agustin; TEIXEIRA, Manoel Jacobsen; PAIVA, Wellingson SilvaBackground: Ultrasound of the optic nerve sheath diameter (ONSD) has been used as a non-invasive and cost-effective bedside alternative to invasive intracranial pressure (ICP) monitoring. However, ONSD time-lapse behavior in intracranial hypertension (ICH) and its relief by means of either saline infusion or surgery are still unknown. The objective of this study was to correlate intracranial pressure (ICP) and ultrasonography of the optic nerve sheath (ONS) in an experimental animal model of ICH and deter-mine the interval needed for ONSD to return to baseline levels. Methods: An experimental study was conducted on 30 pigs. ONSD was evaluated by ultrasound at differ-ent ICPs generated by intracranial balloon inflation, saline infusion, and balloon deflation, and measured using an intraventricular catheter. Results: All variables obtained by ONS ultrasonography such as left, right, and average ONSD (AON) were statistically significant to estimate the ICP value. ONSD changed immediately after balloon inflation and returned to baseline after an average delay of 30 min after balloon deflation (p = 0.016). No statistical sig-nificance was observed in the ICP and ONSD values with hypertonic saline infusion. In this swine model, ICP and ONSD showed linear correlation and ICP could be estimated using the formula:-80.5 + 238.2 x AON. Conclusion: In the present study, ultrasound to measure ONSD showed a linear correlation with ICP, although a short delay in returning to baseline levels was observed in the case of sudden ICH relief.
- Evaluation of the Maintained Effect of 3% Hypertonic Saline Solution in an Animal Model of Intracranial Hypertension(2016) SOUSA JR., Leonardo M.; ANDRADE, Almir F. de; BELON, Alessandro R.; SOARES, Matheus S.; AMORIM, Robson Luis; OTOCHI, Jose Pinhata; TEIXEIRA, Manoel J.; PAIVA, Wellingson S.Background: Current clinical treatment methods for refractory intracranial hypertension include elevation of the decubitus, ventilation adjustment, and use of hypertonic solutions such as hypertonic saline and mannitol solutions. Previous studies have shown that hypertonic solutions are particularly effective. Although several concentrations of saline solution have been proposed, a 3% solution is the most widely used. The aim of this study was to evaluate the maintained efficacy of a 3% hypertonic saline solution in an experimental model of intracranial hypertension. Material/Methods: A porcine model of reversible intracranial hypertension was created by inserting a balloon catheter into the brain parenchyma, which was inflated and deflated to simulate intracranial hypertension and its surgical correction. The experiment included 3 groups of animals (A, B, and C) with different balloon inflation volumes. In group B, balloons were inflated 2 times to simulate reexpansion. A 20 mL/kg bolus of 3% saline solution was infused using a pump 90 minutes after the start of balloon inflation, and the effects of intracranial pressure were evaluated 60 minutes after infusion. Results: No increases outside of the normal range were observed in mean serum sodium concentrations (p=0.09). In addition, we identified no differences within each group in serum sodium levels measured during hypertonic saline infusion (p=0.21). No significant reductions in intracranial pressure were observed in any of the 3 groups. Conclusions: Bolus infusion of 3% hypertonic saline solution with the aid of a pump does not significantly reduce intracranial pressure in an animal model of intracranial hypertension.
- The influence of intracranial hypertension on static cerebral autoregulation(2020) DE-LIMA-OLIVEIRA, Marcelo; FERREIRA, Almir Andrade; BELON, Alessandro Rodrigo; SALINET, Angela Macedo; NOGUEIRA, Ricardo Carvalho; PING, Brasil Chian; PAIVA, Wellingson Silva; TEIXEIRA, Manoel Jacobsen; BOR-SENG-SHU, EdsonObjectives To analyze the influences of mild and severe intracranial hypertension on cerebral autoregulation (CA). Patients and Methods Duroc piglets were monitored with an intracranial pressure (ICP) catheter. Intracranial hypertension was induced via infusion of 4 or 7 ml of saline solution by a bladder catheter that was inserted into the parietal lobe. The static cerebral autoregulation (sCA) index was evaluated via cerebral blood flow velocities (CBFv). Piglets with ICPs <= 25 and > 25 mmHg were considered as group 1 and 2, respectively. Continuous variables were evaluated using the Kolmogorov-Smirnov goodness-of-fit test. The main parameters were collected before and after ICH induction and compared using two-factor mixed-design ANOVAs with the factor of experimental group (mild and severe ICH). Results In group 1 (ICP <= 25 mmHg), there were significant differences in sCA (p= .01) and ICP (p= .0002) between the basal and balloon inflation conditions. In group 2 (ICP > 25 mmHg), there were significant differences in CBFv (p= .0072), the sCA index (p= .0001) and ICP (p= .00001) between the basal and balloon inflation conditions. Conclusion We conclude that ICH may have a direct effect on mild and severe sCA.
- Assessing ultrasonographic optic nerve sheath diameter in animal model with anesthesia regimens(2022) AZEVEDO, Maira de Robertis; DE-LIMA-OLIVEIRA, Marcelo; BELON, Alessandro Rodrigo; BRASIL, Sergio; TEIXEIRA, Manoel Jacobsen; PAIVA, Wellingson Silva; BOR-SENG-SHU, EdsonPurpose: To determine the normal optical nerve sheath (ONS) diameter ultrasonography (ONSUS) and evaluate the possible effects of drugs on ONS diameter during anesthetic induction in healthy pigs. Methods: Healthy piglets were divided into three groups: a control group, that received xylazine and ketamine (X/K); other that received xylazine, ketamine and propofol (X/K/P); and a third group that received xylazine, ketamine, and thiopental (X/K/T). The sheath diameter was assessed by ultrasonography calculating the average of three measurements of each eye from the left and right sides. Results: 118 animals were anesthetized (49 X/K 33 X/K/P and 39 X/K/T). Mean ONS sizes on both sides in each group were 0.394 +/- 0.048 (X/K), 0.407 +/- 0.029 (X/K/P) and 0.378 +/- 0.042 cm (X/K/T) (medians of 0.400, 0.405 and 0.389, respectively). The ONS diameter varied from 0.287-0.512 cm (mean of 0.302 +/- 0.039 cm). For group X/K, the mean diameter was 0.394 +/- 0.048 cm. Significant differences in ONS sizes between the groups P and T (X/K/P > X/K/T, p = 0.003) were found. No statistically significant differences were detected when other groups were compared (X/K = X/K/P, p = 0.302; X/K = X/K/T, p = 0.294). Conclusion: Sedation with thiopental lead to significative ONS diameter reduction in comparison with propofol. ONSUS may be useful to evaluate responses to thiopental administration.
- Large-for-size liver transplantation: a flowmetry study in pigs(2014) MOREIRA, Daniel de Albuquerque Rangel; TANNURI, Ana Cristina Aoun; BELON, Alessandro Rodrigo; COELHO, Maria Cecilia Mendonca; GONCALVES, Josiane Oliveira; SERAFINI, Suellen; LIMA, Fabiana Roberto; AGOSTINI, Luciana Orsi; GUIMARAES, Raimundo Renato; TANNURI, UenisBackground: Ischemia-reperfusion injury is partly responsible for morbidity in pediatric liver transplantation. Large-for-size (LFS) liver transplantation has not been fully studied in the pediatric population, and the effects of reperfusion injury may be underestimated. Materials and methods: Thirteen Landrace-Large white pigs weighing 23 kg (range, 17-38 kg) underwent orthotopic liver transplantation. They were divided into two groups according to the size of the donor body: LFS and control (CTRL). After transplantation, the abdominal cavity of the recipient was kept open and portal venous flow (PVF) was measured after 1 h. The ratio of recipient PVF (PVFr) to donor PVF was used to establish correlations with ischemia and reperfusion parameters. Liver biopsies were taken 1 h after transplantation to assess ischemia and reperfusion and to quantify the gene expression of endothelial nitric oxide synthase, interleukin 6, BAX, and BCL. Results: Recipient weight, total ischemia time, and warm ischemia time were similar between groups. Among hemodynamic and metabolic analyses, pH, central arteriovenous PCO2 difference, and AST were statistically worse in the LFS group than in the CTRL group. The same was found with endothelial nitric oxide synthase (0.41 +/- 0.18 versus 1.56 +/- 0.78; P = 0.02) and interleukin 6 (4.66 +/- 4.61 versus 16.21 +/- 8.25; P = 0.02). In the LFS group, a significant decay in the PVFr was observed in comparison with the CTRL group (0.93 +/- 0.08 and 0.52 +/- 0.11, respectively; P < 0.001). Conclusions: The implantation of a graft was responsible for poor hemodynamic status of the recipient 1 h after transplantation. Furthermore, the LFS group demonstrated markers of ischemia and reperfusion that were worse when compared with the CTRL group and exhibited a more significant decrease in PVF from donor to recipient.
- Does a meso-caval shunt have positive effects in a pig large-for-size liver transplantation model?(2017) TANNURI, Ana Cristina Aoun; MOREIRA, Daniel de Albuquerque Rangel; BELON, Alessandro; COELHO, Maria Cecilia Mendonca; GONCALVES, Josiane Oliveira; SERAFINI, Suellen; TANNURI, UenisIn pediatric liver transplantations with LFS grafts, higher incidences of graft dysfunction probably occur due to IRI. It was postulated that increasing the blood supply to the graft by means of a meso-caval shunt could ameliorate the IRI. Eleven pigs underwent liver transplantation and were divided into two groups: LFS and LFS+SHUNT group. A series of flowmetric, metabolic, histologic, and molecular studies were performed. No significant metabolic differences were observed between the groups. One hour after reperfusion, portal flow was significantly lower in the recipients than in the donors, proving that the graft was maintained in low portal blood flow, although the shunt could promote a transient increase in the portal blood flow and a decrease in the arterial flow. Finally, it was verified that the shunt promoted a decrease in inflammation and steatosis scores and a decrease in the expression of the eNOS gene (responsible for the generation of nitric oxide in the vascular endothelium) and an increase in the expression of the proapoptotic gene BAX. The meso-caval shunt was responsible for some positive effects, although other deleterious flowmetric and molecular alterations also occurred.
- Does Arterialization of Portal Vein Have Any Effects in Large-for-Size Liver Transplantation? Hemodynamic, Histological, and Biomolecular Experimental Studies(2022) TORRES, Rafael Rodrigues; TANNURI, Ana Cristina Aoun; SERAFINI, Suellen; BELON, Alessandro; GONCALVES, Josiane Oliveira; LORETO, Celso di; TANNURI, UenisBackground: In pediatric liver transplantation, the optimal size of the transplanted liver ranges between 0.8% and 4.0% of the recipient's weight. Sometimes, the graft weight exceeds this upper limit, characterizing the large-for-size condition potentially associated with reduced blood flow and worsening of ischemia-reperfusion injury. Therefore, it would be beneficial to increase the portal flow through arterialization of the portal vein. Materials and methods: Fifteen pigs underwent large-for-size liver transplants. They were divided into two groups: control (CTRL 6 animals - conventional technique) and arterialization - a shunt was established between the portal vein and the splenic artery (ART 9 animals). Hemodynamic, biochemical, histological, and molecular variables were compared. Results: Arterialization resulted in a significant increase in portal vein pressure but no changes in other hemodynamic variables, as shown in the analysis of variance. It was observed lower ALT values (p = 0.007), with no differences regarding the values of blood pH and lactate (p = 0.54 and p = 0.699 respectively) or histological variables (edema, steatosis, inflammation, necrosis, and IRI - p = 1.0, p = 0.943, p = 0.174, p = 0.832, p = 0.662, respectively). The molecular studies showed significantly increased expression of IL6 after 3 hours of reperfusion (p = 0.048) and decreased expression of ICAM immediately after reperfusion (p = 0.03). The regression analysis suggested a positive influence of portal flow and pressure on biochemical parameters. Conclusion: Arterialization of the portal vein showed no histological, biochemical, or molecular benefits in large-for-size transplantation.
- A NEW MODEL OF LARGE-FOR-SIZE PORCINE LIVER TRANSPLANTATION WITH AORTIC CLAMPING(2013) LEAL, Antonio Jose Goncalves; BELON, Alessandro Rodrigo; TANNURI, Ana Cristina Aoun; GUIMARAES, Raimundo Renato Nunes; COELHO, Maria Cecilia Mendonca; GONCALVES, Josiane De Oliveira; SOKOL, Suellen Serafini; MELO, Evandro Sobroza De; OTOCH, Jose Pinhata; TANNURI, UenisOBJECTIVE: The objective of the present study was to create a swine model of large-for-size liver transplantation, without venovenous bypass but clamping of the supraceliac aorta during the hepatic phase. MATERIAL AND METHODS: Fourteen Landrace-Large white pigs (weight 17 to 20 kg) were anesthetized with continuous infusion of propofol and fentanyl, and mechanically ventilated. They underwent orthotopic liver transplantation(OLT) with whole liver grafts and were divided randomly into two experimental groups, according to donor size. Regular size group (NS-n=7): donors weight were similar to the receptors (17–20 kg). Large-for-size group (LFS-n=7): donors weight was nearly two times the receptor ′ s (40–50 kg). Blood for serum levels of aspartate aminotransferase (AST) and hepatic tissue for histological examination and quantification of Bax (a proapoptotic protein) gene expression though real time PCR were sampled from the recipient at baseline, 1 and 3 h after portal reperfusion. RESULTS: In NS group, one death was related to hemodynamic instability just after aortic release and another due to bleeding by laceration on graft surface. In LFS 1,3 group, the two deaths were associated to hemodynamic instability just after aortic release. Table 1 shows the changes in AST levels over the experiment in both groups. Table 2 presents the histological results. Table 3 shows the results of Bax gene expression for the NS and LFS groups. CONCLUSION: This large-animal model is straightforward, reproducible, and clinically relevant. It provides the appropriate size and anatomy that resemble humans for the development and practice of new surgical techniques.
conferenceObject VARIATION OF OPTICAL NERVE SHEATH DIAMETER DURING ANESTHESIA IN EXPERIMENTAL MODEL WITHOUT INTRACRANIAL HYPERTENSION(2017) BRASIL, S.; DE-LIMA-OLIVEIRA, M.; PAIVA, W.; BOSSE, E.; BOR-SENG-SHU, E.; EVANGELISTA, M.; TEIXEIRA, M. Jacobsen; BELON, A.; AZEVEDO, M.