Tomáz de Jesus Maria Grezzana Filho

Oxidative stress evaluation of ischemia and reperfusion in kidneys under various degrees of hypothermia in rats

PURPOSE To design an animal model of ischemia-reperfusion (I/R) in kidneys and evaluate the role that predetermined ranges of local hypothermia plays on markers of stress-oxydative as well as on histologic sections. METHODS Twenty eight male rats Wistar, under general anesthesia, undergone right nephrectomy (G0, control group) followed by left kidney ischemia during 40 min. Four temperatures groups were designed, with seven animals randomized for each group: normothermic (G1, ±37ºC), mild hypothermia (G2, 26ºC), moderate hypothermia (G3, 15ºC) and deep hypothermia (G4, 4ºC). Left kidney temperature was assessed with an intraparenchymal probe. Left nephrectomy was performed after 240 min of reperfusion. After I/R a blood sample was obtained for f2-IP. Half of each kidney was sent to pathological evaluation and half to analyze CAT, SOD, TBARS, NO3, NO2. RESULTS Histopathology showed that all kidneys under I/R were significantly more injured than the G0 (p<0.001). TBARS had increased levels in all I/R groups compared with the G0 (p<0.001). CAT had a significant difference (p<0.03) between G1 and G4. Finally, no difference was found on SOD, NO3, NO2 nor on f2-IP. CONCLUSION This model of I/R was efficient to produce oxidative-stress in the kidney, showing that 4ºC offered significant decrease in free radicals production, although tissue protection was not observed.

Topical hepatic hypothermia plus ischemic preconditioning: analysis of bile flow and ischemic injuries after initial reperfusion in rats

PURPOSE To evaluate the effects of the topical liver hypothermia and IPC combination against I/R injury after initial reperfusion. METHODS In 32 Wistar rats, partial liver ischemia was induced for 90 minutes in normothermia (IN), ischemic preconditioning (IPC), 26ºC topical hypothermia (H) and 26ºC topical hypothermia plus IPC (H+IPC). MAP, body temperature and bile flow were recorded each 15 minutes. Plasmatic injury markers and tissue antioxidant defenses were assessed after 120 minutes of reperfusion. RESULTS MAP and body temperature remained constant during all experiment. Bile flow returned to levels similar to controls after 45 minutes of reperfusion in the H and H+IPC groups and increased significantly in comparison to the NI and IPC groups after 105 and 120 minutes. AST and ALT increased significantly in the normothermic groups in comparison to controls. TBARS levels decreased significantly in the H+IPC group in comparison to the other groups whereas Catalase levels increased significantly in the IPC group. SOD levels were significantly higher in the H group in comparison to all groups. CONCLUSION The induction of 26ºC topical hypothermia associated or not to IPC protected the ischemic liver against ischemia/reperfusion injuries and allowed an early recovery of the hepatic function.

Liver glutathione depletion after preservation and reperfusion in human liver transplantation

PURPOSE The oxidative stress is an important mechanism responsible for dysfunction after orthotopic liver transplantation (OLT). Glutathione (GSH) low levels after cold storage render the grafts vulnerable to reperfusion injury. Aim of this study was to evaluate GSH and oxidized glutathione (GSSG) liver concentrations, the hepatocellular injury and function in optimal and suboptimal grafts after human OLT. METHODS Liver biopsies were taken in 33 patients before the implant and two hours after reperfusion, allowing determination of GSH, GSSG and oxidative stress ratio (GSH/GSSG). Serum transaminases, prothrombin activity (PT) and factor V were measured to evaluate injury and function respectively. Histopathological injury was analyzed by an index of five parameters. RESULTS There was a decrease in GSH (p<0.01) after reperfusion (0.323 +/- 0.062 ìmol/g to 0.095 +/- 0.01 ìmol/g and 0.371 +/- 0.052 ìmol/g to 0.183 +/- 0.046 ìmol/g) in suboptimal and optimal groups, respectively. An increase of GSSG (p<0.05) occurred after reperfusion (0.172 +/- 0.038 ìmol/g to 0.278 +/- 0.077 ìmol/g and 0.229 +/- 0.048 ìmol/g to 0.356 +/- 0.105 ìmol/g) in suboptimal and optimal groups, respectively. A decrease (p<0.01) occurred in the GSH/GSSG ratio after reperfusion (2.23 +/- 0.31 to 0.482 +/- 0.042 and 2.47 +/- 0.32 to 0.593 +/- 0.068) in suboptimal and optimal groups, respectively. Histopathological injury scores were higher (p<0.05) in the suboptimal group than in optimal (6.46 +/- 0.4 vs. 5.39 +/- 1.1) and showed correlation with PT and factor V in the optimal group (p<0.05). Multivariate analysis pointed steatosis as an independent risk factor to histopathological injury (p<0.05). CONCLUSION There was a significant GSH depletion and GSSG formation after cold storage and reperfusion due to a similar oxidative stress in optimal and suboptimal grafts, but these levels were not related to graft viability.

Topic liver hypothermia and ischemic preconditioning: a new model of ischemia and reperfusion in rats

PURPOSE Evaluation of the Mean Arterial Pressure (MAP) and body temperature changes in a new model of liver ischemia-reperfusion applying topical Hypothermia and Ischemic Preconditioning (IPC). METHODS Rats (n= 32) were divided in 5 groups: Control (C), Normothermic Ischemia (NI), Ischemic Preconditioning (IPC), Hypothermia 26 degrees C plus IPC (H+IPC) and Hypothermia 26 degrees C (H). MAP and body temperature were recorded at 30 minutes intervals throughout the entire experiment. The study groups underwent 90 minutes partial hepatic ischemia followed by 120 minutes of reperfusion. The median and lateral left lobes were isolated and topical 26 degrees C hypothermia was induced by superfusion of cooled saline solution in H+IPC and H groups. A 10 minutes protocol of ischemia and reperfusion was applied in the IPC and H+IPC groups before the major ischemic insult. RESULTS There was no significant difference in MAP and body temperature means between the groups throughout the experiments. CONCLUSION The present model allows the induction of topical hepatic hypothermia associated or not to IPC. New studies to evaluate the possible synergistic effects of these tools can be reproduced without significant changes in macrohemodynamics and body temperature, or in other words, under stable conditions.

Achieving good perioperative outcomes after pancreaticoduodenectomy in a low-volume setting: a 25-year experience.

Perioperative mortality following pancreaticoduodenectomy has improved over time and is lower than 5% in selected high-volume centers. Based on several large literature series on pancreaticoduodenectomy from high-volume centers, some defend that high annual volumes are necessary for good outcomes after pancreaticoduodenectomy. We report here the outcomes of a low annual volume pancreaticoduodenectomy series after incorporating technical expertise from a high-volume center. We included all patients who underwent pancreaticoduodenectomy performed by a single surgeon (ADC.) as treatment for periampullary malignancies from 1981 to 2005. Outcomes of this series were compared to those of 3 high-volume literature series. Additionally, outcomes for first 10 cases in the present series were compared to those of all 37 remaining cases in this series. A total of 47 pancreaticoduodenectomies were performed over a 25-year period. Overall in-hospital mortality was 2 cases (4.3%), and morbidity occurred in 23 patients (48.9%). Both mortality and morbidity were similar to those of each of the three high-volume center comparison series. Comparison of the outcomes for the first 10 to the remaining 37 cases in this series revealed that the latter 37 cases had inferior mortality (20% versus 0%; P = 0.042), less tumor-positive margins (50 versus 13.5%; P = 0.024), less use of intraoperative blood transfusions (90% versus 32.4%; P = 0.003), and tendency to a shorter length of in-hospital stay (20 versus 15.8 days; P = 0.053). Accumulation of surgical experience and incorporation of expertise from high-volume centers may enable achieving satisfactory outcomes after pancreaticoduodenectomy in low-volume settings whenever referral to a high-volume center is limited.