Samanta Daiana de Rossi

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.

Incidence and endoscopic characteristics of acute laryngeal lesions in children undergoing endotracheal intubation

INTRODUCTION Acute laryngeal lesions after intubation appear to be precursors of chronic lesions. OBJECTIVE To describe the incidence and type of acute laryngeal lesions after extubation in a pediatric intensive care unit (PICU). METHODS A cohort study involving children from birth to <5 years, submitted to intubation for more than 24h in the PICU of an university hospital. In the first eight hours after extubation, a flexible fiberoptic laryngoscopy (FFL) was performed at the bedside. Those with moderate to severe abnormalities underwent a second examination seven to ten days later. RESULTS 177 patients were included, with a median age of 2.46 months. The mean intubation time was 8.19 days. Seventy-three (41.2%) patients had moderate or severe alterations at the FFL, with the remaining showing only minor alterations or normal results. During follow-up, 16 children from the group with moderate to severe lesions developed subglottic stenosis. One patient from the normal FFL group had subglottic stenosis, resulting in an incidence of 9.6% of chronic lesions. CONCLUSION Most children in the study developed mild acute laryngeal lesions caused by endotracheal intubation, which improved in a few days after extubation.