Ebru Ofluoglu

Hepatic Energy Metabolism and the Differential Protective Effects of Sevoflurane and Isoflurane Anesthesia in a Rat Hepatic Ischemia-Reperfusion Injury Model

BACKGROUND: We investigated the effects of isoflurane and sevoflurane in a warm liver ischemia-reperfusion (IR) model on cytokines, hepatic tissue blood flow (HTBF), energy content, and liver structure. METHODS: Seventy-two Wistar rats were randomly assigned into 1 of 3 groups: Control group, no volatile anesthetics; sevoflurane group, 2% sevoflurane; isoflurane group, 1.5% isoflurane. Thirty minutes after the start of volatile anesthetics, rats were subjected to 45 min hepatic ischemia and 2 and 4 h of reperfusion. Rats were killed at the end of ischemia, 2 and 4 h of reperfusion. Aspartate aminotransferase and alanine aminotransferase, HTBF, malondialdehyde, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, energy charge, and histologic examination were used to evaluate the extent of liver injury. RESULTS: Serum alanine aminotransferase and aspartate aminotransferase levels were similar in control and isoflurane groups while there was a significant decrease in the sevoflurane group in the postischemic period (P < 0.01). HTBF was remarkably better in the sevoflurane group than in the isoflurane group and worse in the control group. Tissue malondialdehyde levels were significantly low in the sevoflurane group compared with the isoflurane group at 2 h of reperfusion (P < 0.05) and reached its maximum value in the postischemic period in the control group. After ischemia, 2 and 4 h of reperfusion, tumor necrosis factor-α and interleukin-1β values were lowest in the sevoflurane group and highest in the control group but it was not statistically significant (P > 0.05). In the sevoflurane group, hepatic adenosine triphosphate and energy charge were significantly high at all measurement times. At the postischemic period, energy charge was lower compared with the sevoflurane and isoflurane groups. The degree of hepatocyte injury was small in the sevoflurane group. CONCLUSIONS: Clinically relevant concentrations of sevoflurane given before, during, and after hepatic ischemia protected the liver against IR injury, whereas the effects of isoflurane on hepatic IR injury were not notable.

The Effects of Caffeine on l-Arginine Metabolism in the Brain of Rats

In our study, the short-term effects of caffeine on L- arginine metabolism in the brains of rats were investigated. Caffeine was given orally at two different doses: 30 mg/kg and 100 mg/kg (a high non-toxic dose). Brain tissue arginase activity in rats from the caffeine-treated groups decreased significantly compared with the control group. Malondialdehyde (MDA) levels in the brain tissue and serum of animals in the caffeine groups also decreased significantly. Brain tissue and serum nitric oxide (NO) levels increased significantly after caffeine administration. Tumor necrosis factor-α (TNF-α) levels were also investigated in rat serum, but there was no statistically significant difference between the TNF-α levels of the caffeine-treated rats groups and the control rats. Our study indicates that brain arginase activity decreases after caffeine administration at doses of 30 mg/kg and 100 mg/kg. As a result, we can say that arginine induces production of NO in the organism.

Probiotic Agent Saccharomyces boulardii Reduces the Incidence of Lung Injury in Acute Necrotizing Pancreatitis Induced Rats

BACKGROUND Acute necrotizing pancreatitis is a severe acute inflammatory disease of the pancreas that can lead to extrapancreatic organ involvement. Supervening lung injury is an important clinical entity determining the prognosis of the patient. Probiotics are dietary supplements known to reduce or alter inflammation and inflammatory cytokines. In the present study, we hypothesize that probiotics may reduce lung injury by reducing bacterial translocation, which results in reduced infection, inflammation, and generation of proinflammatory cytokines in an experimental model of acute necrotizing pancreatitis. METHODS Pancreatitis was induced by concomitant intravenous infusion of cerulein and glycodeoxycholic acid infusion into the biliopancreatic duct. Saccharomyces boulardii was used as the probiotic agent. Rats were divided into three groups: sham, pancreatitis-saline, which received saline via gavage at 6 and 24 h following the pancreatitis, pancreatitis-probiotics, which received probiotics via gavage method at 6 and 24 h following the pancreatitis. The rats were sacrificed at 48 h, venous blood, mesenteric lymph node, pancreatic and lung tissue samples were obtained for analysis. RESULTS Serum pancreatic amylase, lactate dehydrogenase, secretory phospholipase A(2), and IL-6 were found to be increased in pancreatitis-saline group compared with the other groups (P < 0.05). Histological analyses revealed that edema, inflammation, and vacuolization as well as polymorphonuclear leukocyte infiltration in the lung tissue was significantly reduced in the probiotic treated group. Bacterial translocation was significantly reduced in the probiotic treated group compared with the other groups (P < 0.05). CONCLUSION These results suggest that Saccharomyces boulardii reduce the bacterial translocation. As a result of this, reduced proinflammatory cytokines and systemic inflammatory response was observed, which may be the reason underlying reduced lung injury in acute necrotizing pancreatitis.

Does sildenafil reverse the adverse effects of ischemia on ischemic colon anastomosis: yes, 'no'.

INTRODUCTION Sildenafil may lead an improvement in anastomotic healing of ischemic left colon anastomosis. METHODS Thirty-six male Wistar albino rats were randomized into four experimental groups (n=9 in each group). In group 1, a well-perfused left colonic segment was transected, and free ends were anatomosed. In groups 2, 3 and 4 animals underwent a standardized surgical procedure to induce ischemic left colon anastomosis. Group 2 animals received only tap water. In groups 3 and 4 animals received 10mg/kg/body-weight and 20mg/kg/body-weight sildenafil, single dose a day during 4 days, respectively. Rats were sacrificed on day 4 following operation. Anastomotic integrity, intra-peritoneal adhesion scores, anastomotic bursting pressures and tissue hydroxyproline levels were recorded. Histopathological examination of the anastomosis was also performed. RESULTS There was no statistically significant difference among groups with respect to anastomotic integrity (p=0.142) but ischemia decreased the anastomotic bursting pressure. The mean bursting pressure values were 78.8+/-24.1, 43.3+/-26, 55.1+/-32.4, and 43.3+/-20.4 in groups 1, 2, 3, and 4, respectively. Group 1 had the highest values whereas; there was no statistically significant difference between groups 1 and 3. There was no statistically significant difference among groups 2, 3, and 4 with respect to tissue hydroxyproline levels, adhesion scores and the Chiu scores. The highest inflammatory cell presence in the granulation tissue was detected in group 2, whereas the lowest was detected in group 4 (p=0.0001). The highest fibroblast infiltration in the granulation tissue was detected in group 1 (p=0.045). DISCUSSION Our results showed that 10mg/kg sildenafil decreased the adverse effects of ischemia on the healing of ischemic left colon anastomosis. Additional investigations are needed to confirm the effects of phosphodiesterase-5 inhibitors in ischemic colon anastomosis models.

Ultrastructure protection and attenuation of lipid peroxidation after blockade of presynaptic release of glutamate by lamotrigine in experimental spinal cord injury

OBJECT Lamotrigine is an antiepileptic drug that inhibits presynaptic voltage-gated sodium channels and reduces the presynaptic release of glutamate in pathological states. Neuroprotective effects of this drug have already been demonstrated in cerebral ischemia models. The aim of the present study was to determine the effects of presynaptic glutamate release inhibition on experimental spinal cord injury (SCI). METHODS A total of 66 adult Wistar rats were randomly allocated into 6 groups. Group I was the control group used to obtain normal blood samples and spinal cord specimens. Spinal cord injury was introduced by using the extradural clip compression technique, but no medication was given to Group II (trauma group) rats. Group III was treated with vehicle, and the same amount of dimethyl sulfoxide used in treatment groups was administered to these rats. A dose of 50 mg/kg lamotrigine was administered intraperitoneally to Group IV (pretreatment), Group V (peritreatment), and Group VI (posttreatment) rats 30 minutes before, during, and 30 minutes after SCI, respectively. Oxidative stress parameters and transmission electron microscopic findings were examined. RESULTS Blockade of presynaptic release of glutamate by lamotrigine treatment yielded protective effects on the spinal cord ultrastructure even when administered after the SCI, but it prevented oxidative stress only when it was administered before or during the SCI. CONCLUSIONS Currently, no available agent has been identified, that can block all the glutamate receptors at the same time. To prevent excitotoxicity in SCI, inhibiting glutamate release from the presynaptic buttons instead of blocking the postsynaptic glutamate receptors seems to be a more rational approach. Further research, such as neurobehavioral assessment, is warranted to demonstrate the probable neuroprotective effects of presynaptic glutamate release inhibition in SCI.

Delayed Energy Protection of Ischemic Preconditioning on Hepatic Ischemia/Reperfusion Injury in Rats

Background: Hepatic ischemia/reperfusion (IR) injuries associated with hepatic resections are unresolved problems in the clinical practice. The aim of this study is to elucidate the effect of ischemic preconditioning (IPC) on the energy charge (EC) and related mechanisms at the late phase of hepatic IR injury. Methods: 30 Wistar rats were randomly divided into sham, IR and IPC groups. The model of partial hepatic IR was used. The rats were subjected to 60 min hepatic ischemia, pretreated by IPC (10/15 min) or not. After 24 h of reperfusion, serum alanine aminotransferase (ALT), nitrite/nitrate (NOx), malondialdehyde (MDA), hepatic tissue arginase activity, adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and EC of the liver were measured. Results: Liver injury reduced by IPC is measured by liver tissue arginase activity and serum ALT. Tissue NOx levels in rats pretreated with IPC were significantly higher than levels in the IR group (p < 0.001). Tissue levels of MDA in the liver of the IPC group were found to be significantly lower than the levels in the IR group (p < 0.001). ATP and EC levels 24 h after hepatic ischemia in rats pretreated with IPC were higher than the levels in the IR (p < 0.05). All groups had similar ADP and AMP levels in the liver tissues. The IPC procedure significantly reduced the hepatic necrosis (p < 0.001). Conclusion: The results of this study demonstrated that pretreatment with IPC improved tissue ATP, EC, and hepatic necrosis at late stages of ischemia reperfusion injury of the liver. Increased nitric oxide, reduced MDA and arginase activity seemed to play a regulatory role in this delayed protective effect of IPC.

Ischemic preconditioning improves liver regeneration by sustaining energy metabolism after partial hepatectomy under ischemia in rats.

Abstract: Background: The protective effect of ischemic preconditioning (IPC) has been reported on improvement of survival, reduction of liver necrosis and enhancement of the regenerative capacity of hepatocytes after partial hepatectomy. This study was undertaken to confirm that IPC has a significant impact on regeneration of hepatocytes after partial hepatectomy in ischemically damaged liver. In addition, we sought to examine the role of adenine nucleotides in this process.

Effects of two conventional preoperative radiation schedules on anastomotic healing in the rat colon.

Background: Preoperative radiotherapy (RT) is an increasingly popular form of adjunct therapy for rectal cancer; however, little is known about its effects on matrix metalloproteinase (MMP) expression in colonic anastomotic healing. Methods: Wistar rats were irradiated to a total dose of 25 or 40 Gy. Four days after the end of RT, an end-to-end colorectal anastomosis was performed. Animals were sacrificed at 1, 3, and 7 days after the anastomosis. A control group was studied similarly, but was not irradiated. Results: No significant differences were found in peritonitis rate and anastomotic complications. The average bursting pressure and breaking strength were only reduced significantly in the rats irradiated with 40 Gy. However, the concentration and the content of hydroxyproline in anastomotic tissues were unchanged. In irradiated rats, MMP-2 and MMP-9 were significantly increased at 40 Gy, but not at 25 Gy. On the other hand, 25-Gy irradiation induced a smaller increase in the levels of the tissue inhibitors of metalloproteinase-1 compared with the controls. Conclusion: Anastomotic strength is adversely affected by high-dose fractionated preoperative RT. In contrast, preoperative RT at 25 Gy in five fractions over 5 days is safe with regard to the maintenance of wound strength in colorectal anastomosis.

Effects of Nuclear Factor-κB Inhibitors on Colon Anastomotic Healing in Rats

BACKGROUND Nuclear factor (NF)-κB plays an essential role in inflammation. We tested this role by administering NF-κB-inhibitors into rats undergoing a well-established model of colonic anastomotic healing. METHODS Wistar rats underwent laparotomy, descending colonic transection, and handsewn reanastomosis. The animals were randomized to receive either a selective NF-κB inhibitor (parthenolide 0.5 mg/kg or resveratrol 0.5 mg/kg) or an equal volume of water by gavages before operation and then daily after surgery. Animals were sacrificed either immediately after anastomotic construction (d 0) or at the third, fifth, or seventh postoperative day. RESULTS Both parthenolide and resveratrol treatment led to early significant increases in plasma levels of IL-6. On d 7, hydroxyproline levels were significantly higher in the parthenolide and resveratrol groups. A similar pattern was observed with the bursting pressure. In contrast, gelatinase activity (MMP-2 and MMP-9 expression) was significantly higher in the control group on postoperative d 3. On d 3, expression of NF-κB activity was up-regulated in the anastomotic area. Both parthenolide and resveratrol completely attenuated NF-κB activity. Study groups also developed more marked inflammatory cell infiltration and collagen deposition on histology analysis. CONCLUSIONS Parthenolide and resveratrol significantly improved healing and mechanical stability of colonic anastomoses in rats during the early postoperative period. Both agents may be acting to accelerate the host reparative process as well as to enhance protection of the anastomotic wound bed.

Effects of Everolimus on Cytokines, Oxidative Stress, and Renal Histology in Ischemia-Reperfusion Injury of the Kidney

Background. To evaluate the effects of everolimus on renal ischemia-reperfusion injury (IRI). Methods. Wistar albino rats were divided into control, ischemia-reperfusion (IR), and ischemia-reperfusion/everolimus (IR/eve) groups. Everolimus was administered for seven consecutive days to the IR/eve group prior to injury. IR and IR/eve groups underwent forty-five minutes ischemia followed by the application of reperfusion at 2 and 24 hours. Blood samples and kidneys were taken from all animals. Results. Serum blood urea nitrogen and creatinine levels increased at two hours of reperfusion in the IR and IR/eve groups, and decreased at 24 hours of reperfusion in the IR group. In the IR/eve group, we detected significantly high interleukin-6 levels and low tumor necrosis factor-α and malondialdehyde levels at 24 hours. Myeloperoxidase levels increased at two hours of reperfusion in the IR/eve group, but decreased significantly at 24 hours. Everolimus did not improve renal tubular and interstitial injuries in renal IRI. Conclusions. It has been demonstrated that pretreatment with everolimus has beneficial effects on cytokines and oxidative stress in renal IRI. However, these effects are insufficient for the correction of histopathological changes and restoration of normal kidney function.