***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Objective : To evaluate the protective effects of ischemic preconditioning in a prospect i ve r and omized study involving a large population of unselected patients and to identify factors affecting the protective effects . Summary Background Data : Ischemic preconditioning is an effective protective strategy in several animal models . Protection has also been suggested in a small series of patients undergoing a hemihepatectomy with 30 minutes of inflow occlusion . Whether preconditioning confers protection in other types of liver resection and longer periods of ischemia is unknown . Therefore , we conducted a prospect i ve r and omized study to evaluate the impact of ischemic preconditioning in liver surgery . Methods : A total of 100 unselected patients undergoing major liver resection ( > bisegmentectomy ) under inflow occlusion for at least 30 minutes were r and omized during surgery to either receive or not receive an ischemic preconditioning protocol ( 10 minutes of ischemia followed by 10 minutes of reperfusion ) . Univariate and multivariate analyses were performed to identify independent factors affecting the protective effects of ischemic preconditioning .  ATP contents in liver were measured as a possible mechanism of protection . Results : Both groups ( n = 50 in each ) were comparable regarding age , gender , duration of inflow occlusion , and resected liver volumes . Postoperative serum transaminase levels were significantly lower in preconditioned than in control patients ( median peak AST 364 U/L vs. 520 U/L , P = 0.028 ; ALT 406 vs. 519 U/L , P = 0.049 ) . Regression multivariate analysis revealed an increased benefit of ischemic preconditioning in younger patients , in patients with longer duration of inflow occlusion ( up to 60 minutes ) , and in cases of lower resected liver volume ( < 50 % ) . Patients with steatosis were also particularly protected by ischemic preconditioning .  ATP content in liver tissue was preserved by ischemic preconditioning in young but not older patients . Conclusions : This study establishes ischemic preconditioning as a protective strategy against hepatic ischemia in humans . The strategy is particularly effective in young patients requiring a prolonged period of inflow occlusion , and in the presence of steatosis , and is possibly related to preservation of ATP content in liver tissue . Other strategies are needed in older patients BACKGROUND Clamping of the portal triad ( Pringle maneuver ) prevents blood loss during liver resection , but leads to liver injury upon reperfusion . Ischemic preconditioning ( IP ) has been shown to protect the liver against prolonged ischemic injury in animal models . However , the clinical value of this procedure has not yet been established . METHODS 61 Patients undergoing hepatic resection under inflow occlusion were r and omized to either to receive ( Group-A n = 30 ) or not to receive ( Group-B n = 31 ) an IP ( 10 minutes of ischemia followed 10 minutes of reperfusion ) . RESULTS Mean ( + /- SD)/ Group-A vs. Group-B. Pringle time of 34 + /- 14 and 33 + /- 12 minutes and the extent of resected liver tissue ( 2.7 + /- 1.3 vs. 2.7 + /- 1.1 segments ) were comparable in both groups . Complications , including death , severe liver dysfunction and biliary leakage occurred in 6 patients of Group-A vs. 14 patients of Group-B ( p<0.05 ) . Intraoperative blood loss was significantly lower in Group-A ( 1.28 + /- 0.91 l vs. 1.94 + /- 0.76 l ; p<0.001 ) with 5 vs. 15 patients requiring transfusions ( p<0.01 ) . In a multivariate analysis the duration of the Pringle maneuver ( p<0.05 ) and the absence of preconditioning ( p<0.05 ) were independent predictors for the occurrence of postoperative complications . CONCLUSIONS IP protects against reperfusion injury , reduces the incidence of complications after hepatic resection under inflow occlusion and is simple to use in clinical practice Background / Purpose Continuous inflow vascular occlusion during liver resections causes less severe ischemia and reperfusion injury ( IRI ) if it is preceded by ischemic preconditioning ( IP ) or if intermittent inflow occlusion is used during the resection . No previous clinical trial has studied the effects of adding IP to intermittent inflow occlusion . Methods Consecutive patients ( n = 32 ) with suspicion of malignant liver disease had liver resections ( minimum 2 segments ) performed with inflow occlusion ( intermittent clamping in a manner of 15 min of ischemia and 5 min of reperfusion repetitively ; 15/5 ) . Half of the patients were r and omized to receive IP ( 10 min of ischemia and 10 min of reperfusion before parenchymal transection ; 10/10 ) . The patients were stratified according to volume of resection and none had chronic liver disease . The patients were followed for 5 days with microdialysis ( μD ) . Results All patients completed the study and there were no deaths . No differences were seen between the groups regarding demographics or perioperative parameters ( bleeding , duration of ischemia , resection volume , complications , and serum laboratory tests ) . There were no differences in alanine aminotransferase ( ALT ) , aspartate aminotransferase ( AST ) , bilirubin , or prothrombin time (PT)-INR levels , but μD revealed lower levels of lactate , pyruvate , and glucose in the IP group having major liver resections ( analysis of variance ; ANOVA ) . Nitrite and nitrate levels in μD decreased postoperatively , but no differences were seen between the groups . In one patient an elevated μD – glycerol curve was seen before the diagnosis of a stroke was made . Conclusions IP before intermittent vascular occlusion does not reduce the serum parameters used to assess IRI . IP seems to improve aerobic glucose metabolism , as the levels of glucose , pyruvate , and lactate locally in the liver were reduced , compared to controls , in patients having > 3 segments resected . μD may be used to monitor metabolism locally BACKGROUND / AIMS Liver pathology induced by chemotherapy ( steatosis or vascular injury ) is known to increase the liver 's sensitivity to ischemia/ reperfusion ( I/R ) injury , thereby increasing morbidity and mortality after liver resection . Our aim was to assess whether ischemic preconditioning ( IP ) reduces I/R injury to livers with chemotherapy-induced pathology . METHODS We analyzed a series of livers from patients treated with chemotherapy for colorectal cancer who underwent IP ( n=30 ) or not ( n=31 ) before hepatectomy .  All but one of the livers exhibited  chemotherapy-induced steatosis and / or peliosis before the I/R insult . RESULTS Necrosis was less frequent ( p=0.038 ) in livers with IP than in the others . IP had no influence on apoptosis as assessed by terminal transferase uridyl nick-end labeling ( TUNEL ) assay or caspase-3 , -8 and -9 expression . IP induced a twofold increase in B-cell leukemia/ lymphoma 2 ( Bcl-2 ; p<0.05 ) , which was localized to hepatocytes of centrolobular and peliotic areas and colocalized with the autophagy protein beclin-1 in livers with IP , suggesting their coordinated role in autophagy . Increased expression of the phosphorylated Bcl-2 was observed in preconditioned livers and was associated with a decreased immunoprecipitation of beclin-1 and the increased expression of light chain 3 type II ( LC3-II ) . The increased number of autophagic vacuoles seen by electron microscopy confirmed an association of autophagy in chemotherapy-injured livers following IP . However , the differences in protein expression were not reflected in postresection liver-injury tests or measure of patient morbidity . CONCLUSIONS IP is associated with a reduction in necrosis of hepatocytes already damaged by chemotherapy and an activation of autophagy . Bcl-2 and beclin-1 could be major targets in the regulation of cell death during I/R injury BACKGROUND Two r and omized prospect i ve studies suggested that ischemic preconditioning ( IP ) protects the human liver against ischemia-reperfusion injury after hepatectomy performed under continuous clamping of the portal triad . The primary goal of this study was to determine whether IP protects the human liver against ischemia-reperfusion injury after hepatectomy under continuous vascular exclusion with preservation of the caval flow . STUDY DESIGN Sixty patients were r and omly divided into two groups : with ( n=30 ; preconditioning group ) and without ( n=30 ; control group ) IP ( 10 minutes of portal triad clamping and 10 minutes of reperfusion ) before major hepatectomy under vascular exclusion of the liver preserving the caval flow .  Serum concentrations of aspartate transferase , alanine transferase , glutathione-S-transferase , and bilirubin and prothrombin time were regularly determined until discharge and at 1 month . Morbidity and mortality were determined in both groups . RESULTS Peak postoperative concentrations of aspartate transferase were similar in the groups with and without IP ( 851 + /- 1,733 IU/L and 427 + /- 166 IU/L respectively , p=0.2 ) . A similar trend toward a higher peak concentration of alanine transferase and glutathione-S-transferase was indeed observed in the preconditioning group compared with the control group . Morbidity and mortality rates and lengths of ICU and hospitalization stays were similar in both groups . CONCLUSIONS IP does not improve liver tolerance to ischemia-reperfusion after hepatectomy under vascular exclusion of the liver with preservation of the caval flow . This maneuver does not improve postoperative liver function and does not affect morbidity or mortality rates . The clinical use of IP through 10 minutes of warm ischemia in this technique of hepatectomy is not currently recommended Hepatic pedicle clamping ( HPC ) is widely used to control intraoperative bleeding during hepatectomy ; intermittent HPC is better tolerated but is associated with blood loss during each period of reperfusion . Recently , it has been shown that ischemic preconditioning ( IP ) reduces the ischemia-reperfusion damage for up to 30 minutes of continuous clamping in healthy liver . We evaluated the safety of IP for more prolonged periods of continuous clamping in 42 consecutive patients with healthy liver su bmi tted to hepatectomy .  IP was used in 21 patients ( group A ) ; mean + /- SD of liver ischemia was 54 + /- 19 minutes ( range , 27 - 110 ; in 7 cases > 60 minutes ) . In the other 21 patients , continuous clamping alone was used ( Group B ) ; liver ischemia lasted 36 + /- 14 minutes ( range , 13 - 70 ; in 2 cases > 60 minutes ) . Two patients in Group A ( 9.5 % ) and 3 in Group B ( 14.2 % ) received blood transfusions . In spite of the longer duration of ischemia ( P=.001 ) , patients with IP had lower aspartate aminotransferase ( AST ; P=.03 ) and alanine aminotransferase ( ALT ; P = not significant ) at postoperative day 1 , with a similar trend at postoperative day 3 . This was reconfirmed by multiple regression analysis , which showed that although postoperative transaminases increased with increasing duration of ischemia and of the operation in both groups , the increases were significantly smaller ( P<.001 ) with the use of preconditioning . In conclusion , the present study confirms that IP is safe and effective for liver resection in healthy liver and is also better tolerated than continuous clamping alone for prolonged periods of ischemia . This technique should be preferred to continuous clamping alone in healthy liver . Additional studies are needed to assess the role of IP in cirrhotic liver and to compare IP with intermittent clamping BACKGROUND The Pringle manoeuvre and ischaemic preconditioning are applied to prevent blood loss and ischaemia-reperfusion injury , respectively , during liver surgery . In this prospect i ve clinical trial we report on the intraoperative haemodynamic effects of the Pringle manoeuvre alone or in combination with ischaemic preconditioning . METHODS Patients ( n=68 ) were assigned r and omly to three groups : ( i ) resection with the Pringle manoeuvre ; ( ii ) with ischaemic preconditioning before the Pringle manoeuvre for resection ; ( iii ) without pedicle clamping .  RESULTS Following the Pringle manoeuvre the mean arterial pressure increased transiently , but significantly decreased after unclamping as a result of peripheral vasodilation . Ischaemic preconditioning improved cardiovascular stability by lowering the need for catecholamines after liver reperfusion without affecting the blood sparing benefits of the Pringle manoeuvre . In addition , ischaemic preconditioning protected against reperfusion-induced tissue injury . CONCLUSIONS Ischaemic preconditioning provides both better intraoperative haemodynamic stability and anti-ischaemic effects thereby allowing us to take full advantage of blood loss reduction by the Pringle manoeuvre Ischemic preconditioning ( IPC ) has the potential to decrease graft injury and morbidity  
    Output:
    
IPC decreases hepatocellular damage in liver surgery as determined by transaminases but does not translate to any significant clinical benefit in orthotopic liver transplant or liver resection .
Available clinical evidence does not support routine use of IPC in liver surgery as it does not offer any apparent benefit in perioperative outcome .