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.

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.

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-alpha 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.

Administration of Chlorella sp. microalgae reduces endotoxemia, intestinal oxidative stress and bacterial translocation in experimental biliary obstruction.

RATIONALE: Endotoxemia has long been documented in obstructive jaundice, and altered intestinal barrier function is considered to be one of the important mechanisms for this phenomenon. The aim of this study was to investigate the role of different microalgae (Chlorella sp. and Spirulina sp.) extracts in intestinal barrier function and oxidative stress in experimentally jaundiced rats. METHODS: A total of 60 male wistar rats were randomly divided into four groups of 15 each: I, sham operated; II, bile duct ligation (BDL); III, BDL+Chlorella sp.; IV, BDL+Spirulina sp. Rats were fed rat chow or microalgae extracts supplemented enteral diet ten days after sham operation or BDL. Main outcome measures were endotoxin concentrations in plasma, evidence of bacterial translocation (BT) in mesenteric lymph nodes (MLNs) and liver, oxidative stress, and histology. RESULTS: Compared to the group I, a significant increase in contamined MLNs, liver, and spleen samples and increased endotoxemia were noted in group II (P<0.01) but were significant reduced in group III (P<0.05). There was no significant difference in BT rate between the group II and group IV (P>0.05). Moreover, Chlorella sp. administration protected in jaundiced rats against oxidative stress, as demonstrated by reduction of intestinal lipid peroxidation, increase of the antioxidant reduced glutathione (GSH), and decrease of the oxidized glutathione (GSSG). The intestinal mucosa in control rats was atrophic with significantly decreased villous density and total mucosal thickness. Chlorella sp. caused a significant reduction in villous atrophy compared with controls. CONCLUSIONS: Chlorella sp. microalgae supplemented enteral diet has significant protective effects on intestinal mucosa barrier in obstructive jaundice, and reduces intestinal translocation of bacteria and endotoxin.

Thrombopoietic cytokine and P-selectin levels in patients with multiple myeloma undergoing autologous stem cell transplantation: decrease in posttransplantation P-selectin levels might predict the degree of maximum response.

PURPOSE: This study was designed to determine the pretransplantation levels of thrombopoietic cytokines, which have a fundamental role in both megakaryopoiesis and myeloma pathogenesis and P-selectin in patients with multiple myeloma undergoing autologous hematopoietic stem cell transplantation (AHSCT) and to correlate the cytokine levels with time to platelet recovery. The effect of AHSCT on the levels of the cytokines and its correlation with maximum disease response was also investigated. PATIENTS AND METHODS: The levels of thrombopoietin, interleukin (IL)-6, IL-11, IL-1beta, and P-selectin was measured before and 30 days after AHSCT in 32 patients with a median age of 55 years. The median time to platelet recovery was day +11 (range, 0-14 days) without any significant correlation with pretransplantation cytokine levels. RESULTS: No significant change was observed in thrombopoietic cytokines after AHSCT, whereas serum P-selectin levels showed a significant decrease after AHSCT (P = .001). The decrease in P-selectin was found to be significant in patients who achieved complete remission (P1 = .008) and partial remission (P2 = .018) early after AHSCT. Our data suggest that the level of thrombopoietic cytokines does not have a role in time to platelet recovery. CONCLUSION: The change in P-selectin levels early after transplantation could be a surrogate marker in determining the maximum posttransplantation response.

Effect of 2-octyl-cyanoacrylate on ischemic anastomosis of the left colon.

INTRODUCTION: 2-octyl-cyanoacrylate may be a good alternative in ischemic colon anastomosis without impairment of tissue perfusion. METHODS: Forty male Wistar albino rats were randomized into four experimental groups (n = 10 in each group). In group 1 (control), a well-perfused left colonic segment was transected, and free ends were anastomosed by propylene sutures. In groups 2, 3, and 4, the animals underwent a standardized surgical procedure to induce ischemic left colon anastomosis. In group 2, an end-to-end anastomosis was created using six interrupted 6-0 polypropylene sutures between ischemic edges. In group 3, after approximating the mesenteric and antimesenteric edges of the anastomosis with two 6-0 polypropylene sutures, 2-octyl-cyanoacrylate was applied between the edges. In group 4, anastomosis was created by the same technique as described in group 2, and additionally 2-octyl-cyanoacrylate was applied on suture line. Rats were killed on day 4 following operation. Anastomotic integrity, intraperitoneal adhesion scores, anastomotic bursting pressures, and tissue hydroxyproline levels were recorded. Histopathological examination of the anastomosis was also performed. RESULTS: There were no statistically significant differences among groups with respect to anastomotic integrity (p =.142). The mean bursting pressure values were 81.1 +/- 23.83, 43.3 +/- 26.06, 15.8 +/- 11.3, and 17.6 +/- 18.02 in groups 1, 2, 3, and 4, respectively. There were no statistically significant differences among groups 2, 3, and 4 with respect to tissue hydroxyproline levels and bursting pressure levels. The highest adhesion scores were observed in groups 3 and 4. DISCUSSION: 2-octyl cyanoacrylate does not have additional advantages in the healing of experimental ischemic colon anastomosis.

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.

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-alpha (TNF-alpha) levels were also investigated in rat serum, but there was no statistically significant difference between the TNF-alpha 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.

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.

Effects of microalgae Chlorella species crude extracts on intestinal adaptation in experimental short bowel syndrome.

AIM: To evaluate the effects of chlorella crude extract (CCE) on intestinal adaptation in rats subjected to short bowel syndrome (SBS). METHODS: Wistar rats weighing 230-260 g were used in the study. After anesthesia a 75% small bowel resection was performed. Rats were randomized and divided into groups. Control group (n = 10): where 5% dextrose was given through a gastrostomy tube, Enteral nutrition (EN) group (n = 10): Isocaloric and isonitrogen EN (Alitraq, Abbott, USA), study group (n = 10): CCE was administrated through a gastrostomy tube. Rats were sacrificed on the fifteenth postoperative day and blood and tissue samples were taken. Histopathologic evaluation, intestinal mucosal protein and DNA levels, intestinal proliferation and apoptosis were determined in intestinal tissues, and total protein, albumin and citrulline levels in blood were studied. RESULTS: In rats receiving CCE, villus lengthening, crypt depth, mucosal DNA and protein levels, intestinal proliferation, and serum citrulline, protein and albumin levels were found to be significantly higher than those in control group. Apoptosis in CCE treated rats was significantly reduced when compared to EN group rats. CONCLUSION: CCE has beneficial effects on intestinal adaptation in experimental SBS.

Adipokines and ghrelin in gastric cancer cachexia.

AIM: To investigate the roles of the adipocytokines, ghrelin and leptin in gastric cancer cachexia. METHODS: Resistin, ghrelin, leptin, adiponectin, insulin and insulin-like growth factor (IGF-I), were measured in 30 healthy subjects, and 60 gastric cancer patients of which 30 suffered from cancer-induced cachexia and 30 served as a control group. The relationships between hormones, body mass index (BMI) loss ratio, age, gender, and Glasgow Prognostic Score (GPS) were investigated. RESULTS: Cachexia patients had higher tumor stage and GPS when compared with non-cachexia patients (P < 0.05). Ghrelin, resistin, leptin, adiponectin and IGF-I, showed a significant correlation with BMI loss ratio and GPS (P < 0.05). A strong correlation was seen between GPS and BMI loss (R = -0.570, P < 0.0001). Multivariate analysis indicated that BMI loss was significantly independent as a predictor of ghrelin, resistin, leptin and IGF-I (P < 0.05). Existence of an important significant relationship between resistin and insulin resistance was also noted. CONCLUSION: These results showed that serum ghrelin, leptin, adiponectin, and IGF-I play important roles in cachexia-related gastric cancers. No relationship was found between resistin and cancer cachexia. Also, because of the correlation between these parameters and GPS, these parameters might be used as a predictor factor.

Effect of adrenomedullin on hepatic damage in hepatic ischaemia/reperfusion injury in rats.

AIMS: Adrenomedullin (AM) is a multifunctional peptide with a putative beneficial role after an ischaemic insult. The aim of this study was to evaluate the effect of AM on partial hepatic ischaemia reperfusion (I/R) injury. METHODS: Rats were subjected to 1 h of 70% hepatic ischaemia, followed by reperfusion or sham. At the end of ischaemia, vehicle (phosphate-buffered saline solution), N-nitro-L-arginine methyl ester (L-NAME) and AM with or without L-NAME were infused via the portal vein. Analysis was performed at pre-ischaemia, ischaemia onset and 1, 2 and 4 h after reperfusion. Hepatic tissue blood flow (HTBF) was evaluated by laser Doppler. RESULTS: Plasma AM levels in the I/R groups were significantly lower than the levels in the sham group. AM treatment significantly reduced levels of aspartate transaminase and tissue arginase (P<0.05). Significant decreases of tumour necrosis factor-alpha, interleukin-1beta and endothelin-1 levels were also found in the serum. Endothelin-1, malondialdehyde and necrosis were observed more frequently in liver tissue in the AM group than the control (P<0.05). Tissue nitric oxide, energy charge and HTBF were significantly increased in AM treatment experiments (P<0.05). CONCLUSION: The improved HTBF, energy charge and nitric oxide and the reduction of hepatic necrosis, oxidative stress, liver enzymes, endotelin-1 and pro-inflammatory cytokines demonstrate that treatment with AM attenuates liver I/R injury.

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)-alpha, interleukin (IL)-1beta, 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-alpha and interleukin-1beta 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.

Ergothioneine modulates proinflammatory cytokines and heat shock protein 70 in mesenteric ischemia and reperfusion injury.

BACKGROUND AND AIM: Ergothioneine (EGT) is a natural compound that is synthesized by soil bacteria in fungal substrates and exhibits antioxidant functions in many cell models. The purpose of this study was to investigate the effect of EGT on mesenteric ischemia and reperfusion injury. MATERIALS AND METHODS: Rats were supplemented with or without l-ergothioneine (10 mg/kg/d) for 15 days prior to intestinal ischemia. Animals were subjected to ischemia induced by clamping the superior mesenteric artery for 60 min followed by reperfusion. Serum tumor necrosis factor (TNF)-alpha and interleukin-1beta (IL-1beta) levels, tissue malondialdehide (MDA), myleoperoxidase (MPO), and heat shock protein (HSP) 70 levels, as well as histological findings, were evaluated after 1, 2, and 4 h of reperfusion. RESULTS: Serum TNF-alpha and IL-1beta levels, and tissue MDA and MPO activities at 1, 2 and 4 h after reperfusion in the EGT group, were significantly lower than the control group (P < 0.05). Tissue HSP-70 levels of the study group were significantly greater than the control group at any time point of reperfusion. No significant differences in tissue damage including morphological changes ranging from villous denudation to focal necrosis, ulceration, hemorrhage, and architectural disintegration at 1 and 2 h after reperfusion exist between the two groups; however, after 4 h of reperfusion, the tissue damage based on histopathologic scores by Chiu was considerably lower in the study group (P < 0.05). After 4 h of reperfusion, focal epithelial lifting and occasional areas of denuded villi could be seen in the samples of the treated animals, thus preserving villous height and mucosal architecture. CONCLUSION: EGT attenuates mesenteric ischemia reperfusion injury in rat intestine by increasing tissue HSP-70 and decreasing TNF-alpha, IL-1beta, MDA, and MPO levels. EGT also improves morphological alterations, which occurred after IR injury after prolonged periods of reperfusion.

Role of ghrelin and leptin in predicting the severity of acute pancreatitis.

Ghrelin and leptin are the hormones that influence endocrine and exocrine functions of the pancreas and regulate feeding behaviors and energy metabolism. The aim of this study was to investigate the levels of ghrelin and leptin in pancreatitis of different severities and the relation of these hormones with blood glucose level and proinflammatory cytokines. The study was performed on 90 Wistar Albino rats. Three experimental groups composed of 30 rats were established: control group, 0.9% NaCl solution was injected intraperitoneally (i.p); acute edematous pancreatitis (AEP) group, 1 microg/100 g cerulein was injected i.p. five times, at 1-hr intervals; and acute necrotizing pancreatitis (ANP) group, 500 mg/100 g L-arginine was injected i.p. Ten animals in each group were sacrificed under anesthesia 12, 24 and 48 hr after the last injection. After blood withdrawal, the pancreas was totally excised. The levels of blood sugar, lipase, serum tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), ghrelin, and leptin were investigated and histopathologic examination was performed. Following pancreatitis induction, serum ghrelin levels increased at 24 hr and reached the peak level at 48 hr. Its level in the AEP group was higher than in the ANP group. Serum leptin levels in the AEP and ANP groups increased after 12 hr and stayed at high levels until 48 hr compared with the control group. Similarly to ghrelin and leptin, blood glucose levels increased in both pancreatitis groups, but the increase was more prominent in the ANP group, with levels >200 mg/ml at 48 hr. The levels of TNF-alpha and IL-1beta in the AEP and ANP groups reached the peak level at 24 hr and then decreased to a level close to that of the control group at 48 hr. We conclude that serum leptin and ghrelin levels increase in the first 48 hr of AEP and ANP. As the serum ghrelin levels in ANP are higher than in AEP, it can be used as a marker to show the severity of pancreatitis. While TNF-alpha and IL-1beta can be used as a prognostic factor in the first 24 hr, ghrelin and leptin can be used subsequently.

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.

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

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. METHODS: Wistar rats were subjected to 60 min of total hepatic ischemia, followed by 70% hepatectomy. The animals were subdivided into an IPC (10/15 min) group and a non-IPC (control) group. Liver function tests and arginase activity were analyzed. Hepatic adenosine triphosphate (ATP), adenosine diphosphate and adenosine monophosphate were measured using gradient high-performance liquid chromatography. The liver regeneration was identified using relative liver weight and proliferating cell nuclear antigen (PCNA) labeling index. RESULTS: IPC treatment improved serum liver enzymes and tissue arginase activity (P<0.05) when compared with the control group. The preconditioned livers were associated with upregulation of ATP expression and also increased tissue energy charge. Regenerated liver weight in the IPC group was significantly higher than in the control group (P<0.05). The PCNA labeling index in the remnant livers in the IPC group was also significantly increased at 24 and 48 h after partial hepatectomy (P<0.05). CONCLUSION: These results suggest that IPC-augmented liver regeneration after hepatectomy, probably due to the stabilization of energy metabolism in rats.

Effects of ischemic preconditioning on regenerative capacity of hepatocyte in the ischemically damaged rat livers.

BACKGROUND: Liver regeneration after partial hepatectomy is regulated by several factors that activate or inhibit hepatocyte proliferation. A short period of ischemia-reperfusion (IR), called ischemic preconditioning (IPC), protects the liver against subsequent sustained ischemic insults. The present study investigated the effects of IPC on liver regeneration after partial hepatectomy under IR in rats. MATERIALS AND METHODS: Male Wistar rats were subjected to 45 min of total hepatic ischemia, and 70% hepatectomy was performed just before reperfusion. Animals were pre-treated with either IPC (10/15 min) (IPC + PHx group) or not (ischemia + PHx). The survival rate, serum transaminases, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-6 levels, hepatocyte proliferation and histological change of the remnant liver were measured in both groups and compared with non-ischemic controls subjected to 70% hepatectomy alone (PHx group). RESULTS: The survival rate was significantly better in the IPC + PHx group than in the ischemia + PHx group. Furthermore, IPC reduced liver injury determined by liver histology and serum transaminases. There was an early rise in serum TNF-alpha and IL-6 levels in the ischemia + PHx group. Compared with non-ischemic controls, IPC significantly decreased TNF-alpha, but not IL-6 during the late (24 and 48 h) phases of reperfusion. Rats subjected to 70% hepatectomy and 45 min of hepatic ischemia showed significantly reduced hepatocyte proliferation (mitotic index, proliferating cell nuclear antigen, and relative liver weight) when compared with animals subjected to hepatectomy alone. However, hepatocyte proliferation was markedly increased in rats pretreatment with IPC when compared with ischemic controls. CONCLUSION: These results suggest that ischemic pre-conditioning ameliorates the hepatic injury associated with ischemia-reperfusion and has a stimulatory effect on liver cell regeneration that may make it valuable as a hepatoprotective modality. Il-6 appears to be key mediator in promoting regeneration after combined ischemia and hepatic resection.