Carlos Otavio Corso

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.

Hypertonic saline and hemorrhagic shock: hepatocellular function and integrity after six hours of treatment

PURPOSE The comparison after 6 h of hemorrhagic shock (HS) treatment with NaCl 7.5% (Hypertonic Saline Solution-SSH) or Ringer Lactate (RL) on liver function and integrity. METHODS Male Wistar rats were submitted to HS (Mean Arterial Pressure-MAP= 45 mmHg) during 60 min and then treated with NaCl 7.5% (SSH, 10% of blood loss, n=8) or Ringer Lactate (RL, 400% of blood loss, n=8). After 6 h rats were anesthetized, hepatic function was assessed by bile flow measurement and liver integrity evaluated by determination of alanine aminotransferase (ALT) and bilirubin activities. RESULTS There was no difference in MAP between the groups during the whole experiments. Biliary flow showed a significant recovery after SSH treatment (p<0.05), and significant decrease of ALT (p<0.001) and bilirubin levels (p<0.001) in comparison to RL. CONCLUSION Resuscitation of HS with NaCl 7.5% promoted better recovery of liver function and lesser hepatocellular damage after 6 h of treatment compared to RL. The improvement is very likely related to increased microvascular perfusion provided by small volume resuscitation.

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.

Postural education and behavior among students in a city in southern Brazil: student postural education and behavior.

[Purpose] The aim of the present study was to assess the knowledge of the spine and posture among adolescent female students and to determine if they had access to postural education in or outside school. [Subjects and Methods] This was an epidemiological survey of a representative sample of 495 female students aged 14 to 18 years attending a regular secondary school in São Leopoldo, RS, Brazil. Data were collected through a questionnaire. [Results] The results showed that 16.8% of teens did not know what a spine was, 8.3% had no knowledge of posture, and 61% reported receiving no posture education. Posture awareness was associated only with posture while using a computer, while having postural education class was not associated with any postural behavior. [Conclusion] The results showed that, although most students are familiar with the spine and posture, a sizable group is not, and over half had no postural education. These findings suggest that inclusion of postural education programs in schools should be encouraged in order to promote health and prevent diseases related to the spine.

The effects of local ischemic preconditioning and topical hypothermia in renal ischemia/reperfusion injury in rats

PURPOSE Topical hypothermia and local ischemic preconditioning have been shown to reduce renal ischemia-reperfusion (I/R) injury individually. We examined whether combination of both strategies lessens renal I/R injury. METHODS Post right nephrectomy, 40 male Wistar rats were randomly assigned to five experimental protocols performed in the left kidney: topical hypothermia without ischemia (TH), warm ischemia (IR), ischemic preconditioning followed by warm ischemia (IPC+IR), cold ischemia (TH+IR), and ischemic preconditioning followed by cold ischemia (IPC+TH+IR). Eight randomly assigned right kidneys constituted the control group. After 240 min of reperfusion, the left kidney was retrieved to evaluate histological changes, lipid peroxidation and antioxidant enzymes activity. Serum was collected to evaluate urea and creatinine. RESULTS IPC+TH+IR group revealed no difference to any other group subjected to ischemia in relation to histological changes, lipid peroxidation and antioxidant enzymes activity. Creatinine was lower in IPC+TH+IR group compared with IPC+IR, but showed no difference compared to TH+IR group. CONCLUSIONS Combination of local ischemic preconditioning (IPC) and topical hypothermia conferred no protection in renal I/R injury. Moreover, local IPC solely followed by warm ischemia impaired renal function more than warm ischemia alone.

Prevalence of back pain among high school students in a municipality in southern Brazil

Objective: To estimate the prevalence of back pain in adolescent girls, and determine whether this pain is associated with socioeconomic, demographic, anthropometric, and behavioral factors. Methods: This was an epidemiological survey with a representative sample of 495 female high school students, aged 14 to 18 years, in the municipality of Sao Leopoldo in the southern Brazilian state of Rio Grande do Sul. Data were collected through a self-administered questionnaire with closed, standardized, coded, and tested questions. Bivariate analysis included the chi-square test (x2) and calculation of prevalence ratios (α<0.05). Results: The prevalence of back pain was 75.2%. The thoracic-lumbar (30.4%) and lumbar (27.7%) regions of the spine were most affected. Among the students with pain, 60.5% reported the severity of their pain to be moderate to severe, and 21.2% reported that the pain prevented them from performing activities of daily living. Regarding associated factors, the pain was more prevalent in overweight/obese students (RP = 1.246, 95% CI: 1.137 to 1.366), who reported carrying a heavy school backpack/bag (PR = 1.187, 95% CI: 1.073 to 1.314) and those who had incorrect posture when picking up objects from the floor (PR = 1.138, 95% CI: 1.031 to 1.256). Conclusions: There was a high prevalence of back pain associated with body mass index, reported weight of the students school backpack/bag, and posture when picking up objects from the floor.

Analysis of the effects of topical renal hypothermia on lung tissue after kidney ischemia and reperfusion in rats

PURPOSE To evaluate whether topical renal hypothermia (TRH) at different levels of temperature has protective effects on lung tissue after renal I/R, through an analysis of organ histology and inflammatory markers in lung tissue. METHODS Twenty-eight male Wistar rats were randomly allocated across four groups and subjected to renal ischemia at different levels of topical renal temperature: normothermia (no cooling, 37°C), mild hypothermia (26°C), moderate hypothermia (15°C), and deep hypothermia (4°C). To induce I/R, the vessels supplying the left kidney of each animal were clamped for 40 minutes, followed by reperfusion. After four hours, another procedure was performed to harvest the tissues of interest. TNF-α, IL-1β and myeloperoxidase activity were measured in lung tissue. Histological analysis was performed in hematoxylin and eosin-stained lung specimens. RESULTS Induction of renal I/R under deep topical hypothermia resulted in a significant decrease in lung concentrations of TNF-α compared with normothermic I/R (p<0.05). A trend toward significant correlation was found between lung IL-1β concentration and intensity of hypothermia (Spearman r=-0.37; p=0.055). No difference was found in myeloperoxidase activity or histologic injury between groups. CONCLUSION Topical renal hypothermia reduces activation of the inflammatory cascade in the lung parenchyma. However, tissue-protective effects were not observed.

Combined effects of melatonin and topical hypothermia on renal ischemia-reperfusion injury in rats

PURPOSE To evaluate whether their combination was more effective than either alone in decreasing renal damage due to ischemia/reperfusion (I/R) injury in rats. METHODS Thirty-two Wistar rats were assigned to four groups. Following right nephrectomy, their left kidneys were subjected to warm ischemia (IR), cold ischemia (TH+IR), intraperitoneal injection of 10 mg/kg melatonin (MEL+IR), or injection of 10 mg/kg melatonin followed by cold ischemia (MEL+TH+IR). Eight randomly assigned right kidneys constituted the control group. After 240 min of reperfusion, left nephrectomy was performed for histopathological evaluation, lipid peroxidation, and measurement of antioxidant enzyme activity. Serum was collected to measure urea and creatinine concentrations. RESULTS Histopathological damage induced by ischemia and reperfusion was more attenuated in the MEL+TH+IR group than in the MEL+IR and TH+IR groups (p<0.037). Superoxide dismutase activity was significantly higher (p<0.029) and creatinine (p<0.001) and urea (p<0.001) concentrations were significantly lower in the MEL+TH+IR group than in the MEL+IR and TH+IR groups. CONCLUSION The combination of melatonin (MEL) and topical hypothermia (TH) better protects against renal I/R injury than does MEL or TH alone.