Ischemic Preconditioning Group Research Articles

Renal Ischemia/Reperfusion Injury in Diabetic Rats: The Role of Local Ischemic Preconditioning.

Background. The aim of this study was to evaluate the effects of local ischemic preconditioning using biochemical markers and histopathologically in the diabetic rat renal IR injury model. Methods. DM was induced using streptozotocin. Rats were divided into four groups: Group I, nondiabetic sham group (n = 7), Group II, diabetic sham group (n = 6), Group III, diabetic IR group (diabetic IR group, n = 6), and Group IV, diabetic IR + local ischemic preconditioning group (diabetic IR + LIPC group, n = 6). Ischemic renal injury was induced by clamping the bilateral renal artery for 45 min. 4 h following ischemia, clearance protocols were applied to assess biochemical markers and histopathologically in rat kidneys. Results. The histomorphologic total cell injury scores of the nondiabetic sham group were significantly lower than diabetic sham, diabetic IR, and diabetic IR + LIPC groups. Diabetic IR group scores were not significantly different than the diabetic sham group. But diabetic IR + LIPC group scores were significantly higher than the diabetic sham and diabetic IR groups. Conclusion. Local ischemic preconditioning does not reduce the risk of renal injury induced by ischemia/reperfusion in diabetic rat model.

Erratum to: Role of central and peripheral opioid receptors in the cardioprotection of intravenous morphine preconditioning.

Both central and peripheral opioid receptors activation produce cardioprotection. This study investigates the role of central and peripheral opioid receptors in intravenous morphine preconditioning (MPC) and ischemic preconditioning (IPC).Sixty-five anesthetized, open chests, male Sprague-Dawley rats were assigned to one of nine groups after intrathecal catheter placement. IPC was induced by three cycles of intermittent occlusion of left anterior descending artery (5 min occlusion interspersed with 5 min of reperfusion). MPC was induced by three consecutive intravenous infusions of 100 μg/kg morphine over five minutes. The opioid receptors antagonist naloxone methiodide (NM), was intravenously or intrathecally, at a dose of 20 mg/kg or 20 μg/kg, given 10 min before IPC or MPC (IVNM + IPC, ITNM + IPC, IVNM + MPC, ITNM +MPC). Control group (CON) and intravenously or intrathecally administered NM (IVNM, ITNM) were used as negative controls, respectively. All hearts were subjected to 30 min of ischemia follow by 2 h of reperfusion. Infarct size, as a percentage of the area at risk, was determined by 2, 3, 5-triphenyltetrazolium staining. Heart rate and mean arterial blood pressure were monitored.The infarct size was significantly reduced in the IPC and MPC groups compared with control. The additional of intravenous or intrathecal NM both reversed the cardioprotective effects of MPC. In comparison only intravenous administration of NM before IPC could attenuate the cardioprotection.MPC could mimic IPC, produce a similar cardioprotective effect. Both central and peripheral opioid receptors mediate in the cardioprotection of MPC, however, only peripheral opioid receptors in IPC.

Abstract 10467: Inflammation may be Involved in Ischemic Preconditioning in Rat Model of CPR

Background: Ischemia preconditioning (IPC) is a potent strategy that minimizes post-resuscitation cardiac and neurological dysfunction via a K ATP channel-dependent mechanism. Inhibition of inflammation is also related to ischemic tolerance. In this study, we investigate the relation between the two intrinsic mechanisms in a rat model of cardiac arrest and CPR. Hypothesis: Activation of K ATP channels and anti-inflammatory response are two independent mechanisms of IPC to improve post-CPR myocardial and cerebral function. Methods: A total of 24 Sprague-Dawley rats (450-550g) were randomized into three groups (n=8 for each group): 1) control, 8 minutes of untreated ventricular fibrillation (VF) followed by 8 minutes of cardiopulmonary resuscitation and defibrillation; 2) IPC, remote IPC initiated 55 minutes before the induction of VF; 3) IPC+GLIB, glibenclamide (0.3 mg/kg, i.v.) was administered 45 minutes before remote IPC, and rest of protocol was the same as the IPC group. Doppler echocardiography, neurologic deficit score (NDS) scale, and the duration of survival were monitored in all animals. The level of NF-κB, IL-1β, IL-10 were evaluated using the enzyme-linked immunosorbent assay (ELISA). Results: Compared with the control groups, significantly greater CO and EF, lower MPI, improved NDS, and increased duration of survival were observed in both the IPC and IPC+GLIB group during post-resuscitation ( p < 0.05 or 0.01 versus control group). Glibenclamide partly reversed the improvement induced by ischemic preconditioning ( p < 0.05 or 0.01 versus IPC group) (Fig. 1). However, there were no significant differences in biomarkers between the IPC and IPC+GLIB group (Fig. 2). Conclusions: In a rat cardiac arrest model, anti-inflammatory response attenuated the myocardial and neurological dysfunction during the post-resuscitation via a non-K ATP channel-dependent mechanism.

Myths and Facts About the Effects of Ischemic Preconditioning on Performance.

Although numerous studies have demonstrated the effect of ischemic preconditioning (IPC) in clinical application, the effectiveness of this procedure on performance and physiological variables is still debatable. Therefore a systematic review was performed, including a meta-analysis and evaluation of the quality of the papers that addressed this scope. The electronic databases of the National Library of Medicine (PubMed), Google Scholar (using [advanced search], [all fields]) and other online journals were searched, for the following descriptors: a) "ischemic preconditioning"; b) "blood flow" and "hyperemia"; c) "blood flow occlusion," combined with "exercise performance", "athletes", "exercise" and "performance". Relevant studies were included, if they conformed to strict pre-formulated criteria, excluding systematic review articles, meta-analyses and studies with only animals or non-healthy subjects. The 20 studies included had high quality scores (87%). The majority of the studies lacked statistical significance (P<0.05) for both performance and physiological variables when comparing IPC, placebo and control groups. Most studies showed that IPC has no significant influence on performance. The few studies with significant differences mainly described an improvement only in performance without altered physiological parameters. Therefore, the influence of IPC on performance is still unclear and physiologically highly debatable.

Myths and Facts About the Effects of Ischemic Preconditioning on Performance.

Although numerous studies have demonstrated the effect of ischemic preconditioning (IPC) in clinical application, the effectiveness of this procedure on performance and physiological variables is still debatable. Therefore a systematic review was performed, including a meta-analysis and evaluation of the quality of the papers that addressed this scope. The electronic databases of the National Library of Medicine (PubMed), Google Scholar (using [advanced search], [all fields]) and other online journals were searched, for the following descriptors: a) "ischemic preconditioning"; b) "blood flow" and "hyperemia"; c) "blood flow occlusion," combined with "exercise performance", "athletes", "exercise" and "performance". Relevant studies were included, if they conformed to strict pre-formulated criteria, excluding systematic review articles, meta-analyses and studies with only animals or non-healthy subjects. The 20 studies included had high quality scores (87%). The majority of the studies lacked statistical significance (P<0.05) for both performance and physiological variables when comparing IPC, placebo and control groups. Most studies showed that IPC has no significant influence on performance. The few studies with significant differences mainly described an improvement only in performance without altered physiological parameters. Therefore, the influence of IPC on performance is still unclear and physiologically highly debatable.

Remote Ischemic Preconditioning and Outcomes of Cardiac Surgery

BackgroundWhether remote ischemic preconditioning (transient ischemia and reperfusion of the arm) can improve clinical outcomes in patients undergoing coronary-artery bypass graft (CABG) surgery is not known. We investigated this question in a randomized trial.MethodsWe conducted a multicenter, sham-controlled trial involving adults at increased surgical risk who were undergoing on-pump CABG (with or without valve surgery) with blood cardioplegia. After anesthesia induction and before surgical incision, patients were randomly assigned to remote ischemic preconditioning (four 5-minute inflations and deflations of a standard blood-pressure cuff on the upper arm) or sham conditioning (control group). Anesthetic management and perioperative care were not standardized. The combined primary end point was death from cardiovascular causes, nonfatal myocardial infarction, coronary revascularization, or stroke, assessed 12 months after randomization.ResultsWe enrolled a total of 1612 patients (811 in the control group and 801 in the ischemic-preconditioning group) at 30 cardiac surgery centers in the United Kingdom. There was no significant difference in the cumulative incidence of the primary end point at 12 months between the patients in the remote ischemic preconditioning group and those in the control group (212 patients [26.5%] and 225 patients [27.7%], respectively; hazard ratio with ischemic preconditioning, 0.95; 95% confidence interval, 0.79 to 1.15; P=0.58). Furthermore, there were no significant between-group differences in either adverse events or the secondary end points of perioperative myocardial injury (assessed on the basis of the area under the curve for the high-sensitivity assay of serum troponin T at 72 hours), inotrope score (calculated from the maximum dose of the individual inotropic agents administered in the first 3 days after surgery), acute kidney injury, duration of stay in the intensive care unit and hospital, distance on the 6-minute walk test, and quality of life.ConclusionsRemote ischemic preconditioning did not improve clinical outcomes in patients undergoing elective on-pump CABG with or without valve surgery. (Funded by the Efficacy and Mechanism Evaluation Program [a Medical Research Council and National Institute of Health Research partnership] and the British Heart Foundation; ERICCA ClinicalTrials.gov number, NCT01247545.)

The cardioprotective effect of hypoxic and ischemic preconditioning in dogs with myocardial ischemia-reperfusion injury using a double-bypass model.

The effects of preconditioning on cardioprotection have mainly been studied in vitro. No sufficient in vivo experiments have been performed to optimize ischemic preconditioning (IPC) or hypoxic preconditioning (HPC) for clinical applications. The purpose of this study was to establish a canine double-bypass model to examine the effect of IPC and HPC on cardiomyocytes and heart function. A double-bypass procedure to enable independent control of systemic and coronary circulation was established in dogs. The animals were divided into control, HPC, and IPC groups (n=6 each). Indicators of cardiac function, including cardiodynamics, hemodynamics, ATP, and cardiac troponin I (cTnI) levels; myocardium morphology; and myocardiocyte apoptosis were determined. Both IPC and HPC attenuated the reperfusion-induced decrease in left ventricular end systolic pressure seen in the control group. Both the HPC and IPC groups had lower serum cTnI levels, better myocardiocyte histology, and lower rates of apoptosis compared to the control group without preconditioning. HPC reduced the abnormal cardiomyocyte histology and apoptosis to a greater extent than IPC, and only HPC significantly restored the depletion of ATP. This study demonstrates the effectiveness of the double-bypass model for the optimized study of both HPC and IPC. The results suggest that HPC may provide better cardioprotection than IPC.

Remote ischemic preconditioning for prevention of contrast-medium-induced nephropathy: (RenoProtection-trial)

BackgroundContrast-medium-induced acute kidney injury is associated with substantial morbidity and mortality. The underlying mechanism has been partially attributed to ischemic kidney injury. The aim of this randomized, double-blind, sham-controlled trial was to assess the impact of remote ischemic preconditioning on contrast-medium-induced acute kidney injury. MethodsPatients with impaired renal function (serum creatinine >1.4mg/dL and/or estimated glomerular filtration rate <60mL/min/1.73m2) undergoing elective coronary angiography were randomized in a 1:1 ratio to standard care with (n=50) or without ischemic preconditioning (n=50; intermittent arm ischemia through four cycles of 5-min inflation and 5-min deflation of a blood-pressure cuff). Overall, both study groups were at high risk to develop contrast-medium-induced acute kidney injury using Mehran risk score. The primary endpoint was the incidence of contrast-medium-induced kidney injury, defined as an increase of serum creatinine ≥25% and/or ≥0.5mg/dL above baseline at 48h after contrast-medium exposure. ResultsContrast-medium-induced acute kidney injury occurred in 26 patients (26%), 20 (40%) in the control group and 6 (12%) in the remote ischemic preconditioning group (OR 0.21; 95% CI 0.07–0.57; P=0.002). No major adverse events were related to remote ischemic preconditioning. ConclusionsRemote ischemic preconditioning before contrast-medium use prevents contrast medium-induced acute kidney injury in high risk patients. Our findings merit a larger trial to establish remote ischemic preconditioning on clinical outcomes.

Ischemic Preconditioning Mediates Neuroprotection against Ischemia in Mouse Hippocampal CA1 Neurons by Inducing Autophagy.

The hippocampal CA1 region is sensitive to hypoxic and ischemic injury but can be protected by ischemic preconditioning (IPC). However, the mechanism through which IPC protects hippocampal CA1 neurons is still under investigation. Additionally, the role of autophagy in determining the fate of hippocampal neurons is unclear. Here, we examined whether IPC induced autophagy to alleviate hippocampal CA1 neuronal death in vitro and in vivo with oxygen glucose deprivation (OGD) and bilateral carotid artery occlusion (BCCAO) models. Survival of hippocampal neurons increased from 51.5% ± 6.3% in the non-IPC group (55 min of OGD) to 77.3% ± 7.9% in the IPC group (15 min of OGD, followed by 55 min of OGD 24 h later). The number of hippocampal CA1 layer neurons increased from 182 ± 26 cells/mm2 in the non-IPC group (20 min of BCCAO) to 278 ± 55 cells/mm2 in the IPC group (1 min × 3 BCCAO, followed by 20 min of BCCAO 24 h later). Akt phosphorylation and microtubule-associated protein light chain 3 (LC3)-II/LC3-I expression were increased in the preconditioning group. Moreover, the protective effects of IPC were abolished only by inhibiting the activity of autophagy, but not by blocking the activation of Akt in vitro. Using in vivo experiments, we found that LC3 expression was upregulated, accompanied by an increase in neuronal survival in hippocampal CA1 neurons in the preconditioning group. The neuroprotective effects of IPC on hippocampal CA1 neurons were completely inhibited by treatment with 3-MA. In contrast, hippocampal CA3 neurons did not show changes in autophagic activity or beneficial effects of IPC. These data suggested that IPC may attenuate ischemic injury in hippocampal CA1 neurons through induction of Akt-independent autophagy.

Remote Ischemic Preconditioning Improves the Viability of Donor Lipoaspirate during Murine Fat Transfer

Variable results associated with fat grafting have been attributed to local trauma, inconsistencies in transfer, and ischemia before the development of recipient circulation. Remote ischemic preconditioning is an inexpensive noninvasive technique that has been used in animal models and multicenter clinical trials to protect organ systems. In this work, the authors describe a novel animal model for analyzing the efficacy of fat grafting, and investigate the effect of remote ischemic preconditioning on volume retention. Subcutaneous adipose tissue samples from green fluorescent protein/luciferase-expressing FVB mice were obtained with or without pretreatment with a temporary hind-limb tourniquet. The samples were injected into the dorsal skin folds of wild-type FVB mice. The viability of the transferred tissue was examined over a 28-day period with quantitative bioluminescence after luciferin injection. Transferred tissue was also explanted for histologic analysis. The remote ischemic preconditioning group had significantly increased bioluminescence at days 0, 1, and 28. Histologic analysis at day 28 confirmed the presence of vascularized adipose in both groups. However, significant amounts of interstitial fibrosis were found in the control group, whereas substantially less was found in the remote ischemic preconditioning group. The remote ischemic preconditioning group retained a substantially greater amount of green fluorescent protein, suggesting increased survival of donor adipocytes. In this work, the authors describe a novel animal model for quantitative evaluation of fat grafting using in vivo bioluminescence of adipocytes from luciferase-expressing mice. The authors also demonstrate that remote ischemic preconditioning increases the viability of fat transfer and decreases interstitial fibrosis.

Comparative Effects of Ischemic Preconditioning and Iron Chelation in Hepatectomy

ABSTRACTPurpose/Aim: Major hepatectomies can result in severe ischemia/reperfusion (I/R) injury of the liver. The aim of this survey is to comparatively evaluate the effects of a surgical and a pharmacological hepatoprotective modality on the liver remnant in a porcine model of hepatectomy. Material and Methods: Twenty-one Landrace pigs were randomly divided into three groups: a control group (CON) (n = 7), an Ischemic Preconditioning (PRE) group (n = 7) and a Desferoxamine (DFX) treated one (n = 7). Animals were subjected to 120 min of liver ischemia with subsequent 75% hepatectomy followed by 24-hr reperfusion. In all animals, continuous intracranial pressure (ICP) monitoring was employed. Blood samples were collected at t0, t6, t12, and t24 hrs after reperfusion. Liver remnant specimens were excised for histological examination. Results: In the PRE group, ICP was statistically lower at t6 time point compared to CON group and in comparison with t0. In addition, ICP was significantly lower at all-time points after reperfusion in the DFX group. Finally, with regard to DFX and PRE group correlation, ICP was significantly lower at t0, t12, and t24 time points after reperfusion in the DFX group. In the PRE group, NH3 levels were significantly lower at t12 after reperfusion compared to CON and DFX groups. Histological evaluation elucidated significantly less hepatocellular necrosis, apoptosis, and degeneration in the PRE and DFX groups correlated to CON group. Conclusions: Both hepatoprotective modalities including PRE and DFX administration are associated with lower ICP levels and correlated with attenuated liver remnant injury.

Localized lower extremity ischemic preconditioning prevents against local thrombus formation.

Ischemic preconditioning (IPC) has many beneficial effects on the cardiovascular system. However, whether localized lower extremity IPC could be protective against the thrombogenic activity generated by lower extremity ischemia is unclear. 41 male Sprague-Dawley rats were randomly assigned to either a IPC group or a sham group. The lower extremity blood inflow was previously treated with 4 cycles of 5 min ischemia followed by 5 min of reperfusion by clamping the abdominal aortic just before ligature of the left iliac vein(LIV) in the IPC group. Rats in the sham group had a 40-minute blank before left iliac vein ligation. The rats were euthanized at day 2 after ligation and the thrombosed LIV was carefully dissected out, while thrombi harvested from the LIV were measured with weight (g), length (mm) and weight/length (mg/mm). Influence of IPC on coagulation function was also tested. 21 and 20 rats were randomly assigned to einter the IPC group or the control group. Left iliac vein thrombosis was successfully generated in all 41 rats. IPC significantly protects the rats from experimental lower extremity thrombosis. Compared to control group, generated thrombus in rats in the IPC group showed significantly lower weight (2.73 ± 0.16 mg vs 1.82 ± 0.13 mg, P < 0.001), length (2.99 ± 0.17 mm vs 2.44 ± 0.08 mm, P < 0.009) and density (0.95 ± 0.05 mg/mm vs 0.75 ± 0.05 mg/mm, P = 0.01). Influence on coagulation function by IPC itself was not significant (P > 0.05). Our study demonstrated that localized lower extremity IPC could reduce DVT formation in rats in an in vivo experimental thrombosis model.

Protective effect of ischemic preconditioning on the jejunal graft mucosa injury during cold preservation

Protection of intestinal graft mucosa during cold preservation is still an unmet need in clinical practice, thus affecting the success of transplantation. The present study investigates the ability of two ischemic preconditioning (IPC) procedures to limit cold preservation injury. Three groups of Sprague–Dawley rats were recruited (n=11 each) as follows: the short IPC (SIPC) performed through 4cycles of mesenteric ischemia of 4min each followed by 10min of reperfusion, the long IPC (LIPC) obtained by 2 ischemic cycles of 12min each followed by 10min of reperfusion, and the control group (C) without IPC. Grafts were then stored in cold histidine–tryptophan–ketoglutarate solution and samples were taken at 0, 3, 6 and 9h lasting preservation. Both IPC groups showed an advanced degree of preservation with delayed development of graft mucosa damage, mainly in the crypt region. At the beginning of preservation, the graft mucosa in both IPC groups showed lower degree of mucosal injury index (MII) by 50% in comparison with C group. Specifically, a significant improvement of MII was observed after 3h of preservation in the LIPC group (p<0.05) in comparison with untreated C grafts. Significant atrophy of the intestinal mucosa in C group was found after 3h of preservation (p<0.01), in SIPC group the progress of atrophy was delayed to 6h (p<0.001), and in LIPC group only moderate decrease in that was found. A parallel increase of laminin expression with the MII rate after 6 and 9h of preservation in comparison with the level at time 0 was observed in all grafts (p<0.001 and p<0.01, respectively). In both IPC groups the apoptotic cell (AC) rate was significantly reduced at the beginning of cold preservation (p<0.05 both). Moreover, in both the SIPC and C groups, the progressive increase in MII rate connected with AC rate decrease was due to a predominance of necrosis. By contrast in the LIPC group, after an increase of nearly 50% in the AC rate at the 3rd hour, its level remained fairly constant during the further 6h of preservation, thus probably preventing necrosis and improving graft viability.

Identical MicroRNAs Regulate Liver Protection during Anaesthetic and Ischemic Preconditioning in Rats: An animal study.

Anaesthetic preconditioning (APC) and ischemic preconditioning (IPC) ameliorate liver ischemia–reperfusion (I/R) injury and are important for regulating hepatic I/R injury. MicroRNAs (miRNAs) are short, noncoding RNA molecules of 21–23 nucleotides in length, and are currently under intensive investigation regarding their ability to regulate gene expression in a wide range of species. miRNA activity is involved in controlling a wide range of biological functions and processes. We evaluated whether APC and IPC are mediated by the same miRNAs by performing comprehensive miRNA screening experiments in a rat model of hepatic I/R injury. Twenty-one rats were randomly divided into three groups (n = 7/group): control (mock preconditioning), APC, and IPC. Control rats were subjected to 60 min of hepatic ischemia followed by 4 h of reperfusion, whereas the APC and IPC groups were preconditioned with 2% sevoflurane and hepatic ischemia for 10 min prior to ischemia-reperfusion, respectively. Liver samples were collected to measure miRNA levels after 3 h of reperfusion, and gene networks and canonical pathways were identified using Ingenuity Pathway Analysis (IPA). Blood samples were collected to measure the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Although haemodynamic parameters did not vary among the groups, AST and ALT levels were significantly higher in the control group than in the APC and IPC groups. Comprehensive miRNA screening experiments revealed that most miRNAs altered in the APC group were common to those in the IPC group. IPA identified five miRNAs related to the Akt–glycogen synthase kinase-3β (GSK-3β)–cyclin D1 pathway that were significantly affected by both preconditioning strategies. The application of either APC or IPC to ameliorate hepatic I/R injury results in expression of several common miRNAs that are related to the Akt–GSK–cyclin D1 pathway.

Is Ischemic Preconditioning a Useful Therapeutic Strategy in Liver Transplantation? Results from the First Pilot Study in Mexico

The protective effect of ischemic preconditioning (IP) in liver transplantation (LT) has been studied with controversial results. We undertook this study to investigate whether IP of cadaveric donor livers is protective to allografts. IP (LT + IP, n = 6) was induced by 10-min hilar clamping. These were compared to cadaver donors with no IP (LT, n = 7). Clinical data and blood were obtained in donors and recipients for biochemical and inflammatory mediator (IM) measurements (P-selectin, leukotriene B4, myeloperoxidase, ICAM-1, IL-1, IL-6, and TNF-α). Liver tissue samples were obtained from donors and recipients (90 min after reperfusion). No significant differences were found in demographic characteristics between donors and recipients. When comparing both groups (LT + IP vs. LT only), ICU stay was longer in LT + IP group. For biochemical parameters, a significant difference was found only with a higher total bilirubin at postoperative day 3 in LT + IP group. There was no statistical difference in IM between LT and LT + IP groups at different stages of the study. Histological analysis of donor grafts indicated the presence of steatosis (50%) in one graft from the LT + IP group. However, in post-reperfusion biopsies neither neutrophil infiltration nor grade of necrosis showed significant difference between groups. No incidence of primary graft nonfunction (PGNF) was observed and graft and patient survival was similar in the two groups at 24 months. IP does not seem to protect against I/R injury in cadaveric LT, and no PGNF was seen.

PP02.2 – 3073: Very rapid and delayed ischemic precondition against hypoxic-ischemia altered protein sumoylation in neonatal rat brains

Objective Ischemic preconditioning (IP) is well known to protect the brain from a subsequent harmful event. It remains to be determined how quickly does the IP develop and how long does it persist, and whether the IP involved alterations of protein sumoylation, in neonatal hypoxic-ischemic (HI) brain injury. Methods P7 rat pups were subjected to HI by permanent ligation of unilateral common carotid artery followed by hypoxia for 2 h. IP was induced by reversible carotid artery occlusion for 2 h at 30 min (IP-30 min), 22 h (IP-22h), or 72 h (IP-72h) before HI. The outcome was assessed by Morris water maze and neuropathology on P35 and P42, respectively. Western blot and immunohistochemical staining was performed on P7. Results During water-maze training, all three IP groups spent significantly less time finding the submerged platform than no-IP group. In the memory phase, the IP-22h group spent significantly more time in the target quadrant than the no-IP group. The three IP groups had significantly better visual-motor performance than the no-IP group. The histopathology showed that all the three IP groups had significantly less brain area loss in the cortex, hippocampus, and striatum compared with the no-IP group. The no-IP group had prominent increases of cleaved caspase-3 and PARP in the ipsilateral cortex, which were significantly reduced in the three IP groups, with a maximal effect in the IP-22h group 24 h post-HI. HI resulted in an increase in protein sumoylation which was also significantly decreased in all the IP groups. Conclusion In contrast to the limitation of time frame for mature brain, our data demonstrated very rapid and delayed IP in neonatal rat brain altered protein sumoylation and reduced apoptosis after HI, and provided long-term neuroprotection.

Retraction note: Microarray analysis for differentially expressed genes of patients undergoing total knee arthroplasty with ischemia preconditioning.

Ischemia preconditioning (IPC) has been proved as a powerful method of protecting tissues against ischemia reperfusion insults. We aimed to elucidate the mechanism of IPC in ischemia reperfused tissues. GSE21164 containing 16 muscle biopsies taken from the operative knee of four IPC-treated patients and four control at the onset of surgery (T = 0) and 1 h into surgery (T = 1) undergoing primary total knee arthroplasty was downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) between IPC group and control were screened with Limma package in R language. KEGG pathway enrichment analysis was performed by the DAVID online tool. Meanwhile, potential regulatory microRNAs (miRNAs) for downregulated DEGs and targets of transcription factors for upregulated DEGs were screened out. Based on the above DEGs, protein-protein interaction (PPI) networks were constructed by the STRING software. Significantly upregulated DEGs at T1 were mainly enriched in asthma and p53 signaling pathway. Meanwhile, significantly enriched transcriptional factor NOTCH1 at T1 and GABP at T0 were obtained. Moreover, miRNA analysis showed that targets of miR141/200a were enriched in downregulated DEGs both at T0 and T1. Mostly, RPA1 and JAK2 in PPI network at T1 were with higher degree. In our study, obtained DEGs, regulatory transcriptional factors, and miRNA might play a vital role in the protection of ischemia reperfusion injury. This finding will provide a deeper understanding to the mechanism of IPC.

Ischemic preconditioning increases GSK-3β/β-catenin levels and ameliorates liver ischemia/reperfusion injury in rats.

Ischemic preconditioning (IPC) ameliorates ischemia/reperfusion (I/R) injury in a number of organs, and the glycogen synthase kinase-3β (GSK-3β)/β-catenin signaling pathway regulates I/R-induced proliferation and apoptosis in the central nervous system and heart. However, the function of this signaling pathway in IPC during liver I/R remains unclear. Thus, in this study, we aimed to investigte the role of the GSK-3β/β-catenin pathway during I/R and following ischemic preconditioning. For this purpose, 30 Sprague-Dawley rats were randomly divided into the sham-operated, the I/R and the IPC groups (n=10). Following reperfusion, liver pathology, as well as alanine aminotransferase (ALT), aspartate aminotransferase (AST), maleic dialdehyde (MDA) and superoxide dismutase (SOD) levels were assessed. Western blot analysis was performed to quantify the GSK-3β, Ser9-phospho-GSK-3β (p-GSK-3β), cytosolic and nuclear β-catenin, vascular endothelial growth factor (VEGF), Bcl-2 and survivin levels. In addition, the Bcl-2 and survivin mRNA levels were assessed by RT-qPCR. Compared with the sham-operated group, I/R increased serum ALT, AST and MDA activity and decreased SOD levels, while IPC significantly decreased serum ALT, AST and MDA activity and increased SOD levels, compared with the I/R group. Simultaneously, I/R increased p-GSK-3β protein expression, and decreased Bcl-2 and survivin protein and mRNA levels. IPC further increased the protein expression of p-GSK-3β, and also increased cytosolic and nuclear β-catenin and VEGF expression compared with the I/R group; the expression of Bcl-2 and survivin was also increased by IPC, both at the mRNA and protein level. The total GSK-3β expression remained unaltered in all the groups. In conclusion, our data demonstrate that IPC exerts protective effects against liver injury induced by I/R and activates the GSK-3β/β-catenin signaling pathway.

Effects of ischemic preconditioning in a pig model of large-for-size liver transplantation

OBJECTIVE:In most cases of pediatric liver transplantation, the clinical scenario of large-for-size transplants can lead to hepatic dysfunction and a decreased blood supply to the liver graft. The objective of the present experimental investigation was to evaluate the effects of ischemic preconditioning on this clinical entity.METHODS:Eighteen pigs were divided into three groups and underwent liver transplantation: a control group, in which the weights of the donors were similar to those of the recipients, a large-for-size group, and a large-for-size + ischemic preconditioning group. Blood samples were collected from the recipients to evaluate the pH and the sodium, potassium, aspartate aminotransferase and alanine aminotransferase levels. In addition, hepatic tissue was sampled from the recipients for histological evaluation, immunohistochemical analyses to detect hepatocyte apoptosis and proliferation and molecular analyses to evaluate the gene expression of Bax (pro-apoptotic), Bcl-XL (anti-apoptotic), c-Fos and c-Jun (immediate-early genes), ischemia-reperfusion-related inflammatory cytokines (IL-1, TNF-alpha and IL-6, which is also a stimulator of hepatocyte regeneration), intracellular adhesion molecule, endothelial nitric oxide synthase (a mediator of the protective effect of ischemic preconditioning) and TGF-beta (a pro-fibrogenic cytokine).RESULTS:All animals developed acidosis. At 1 hour and 3 hours after reperfusion, the animals in the large-for-size and large-for-size + ischemic preconditioning groups had decreased serum levels of Na and increased serum levels of K and aspartate aminotransferase compared with the control group. The molecular analysis revealed higher expression of the Bax, TNF-alpha, I-CAM and TGF-beta genes in the large-for-size group compared with the control and large-for-size + ischemic preconditioning groups. Ischemic preconditioning was responsible for an increase in c-Fos, IL-1, IL-6 and e-NOS gene expression.CONCLUSION:Ischemia-reperfusion injury in this model of large-for-size liver transplantation could be partially attenuated by ischemic preconditioning.

Protective effects of limbs ischemic preconditioning on lung ischemia-reperfusion injury in rats

Objective To evaluate the effects of limbs ischemic preconditioning on lung ischemiareperfusion injury in rats. Methods Twenty-four male healthy SD rats were randomly divided into 3 groups(n= 8 each):sham group(S group),ischemia-reperfusion group(I/R group)and limbs ischemic preconditioning group(LIPER group). In S group, animals underwent a sham thoracotomy and then the rats were observed for 165 min. In I/R group, the left hilum of lung was occluded with a noncrushing microvascular clamp for 45 min, followed by 120 min reperfusion. In LIPER group, the period of lung ischemia was held constant at 45 min, followed by 120 min reperfusion,and the rats underwent 4 episodes of 5 min legs ischemia at 5 min intervals after lung occlusion for 5 min.Arterial blood samples were taken for blood gas analysis at 120 min of reperfusion. Rats were killed at 120 min reperfusion and lungs were removed for determination of malondialdehyde(MDA)content, lung wet/dry weight ratio(W/D),superoxide dismutase(SOD)and myeloperoxidase(MPO)activities.The lung tissues were subjected to histological examination under a light microscrope,and lung injury was sored. Results At the end of reperfusion, as compared with I/R group, acute lung injury scores in LIPER group were significantly reduced[(6.75± 0.71) vs.(12.13±1.13),P<0.05], pulmonary MDA content in LIPER group was reduced significantly [(0.81±0.05)vs.(1.32±0.09) nmol/mg, P< 0.05], MPO activity in LIPER group was decreased significantly[(2.01±0.17) vs.(4.30±0.22) U/g, P< 0.05], and arterial oxygen partial pressure in LIPER group was significantly increased[(71.0±3.5)vs.(58.5±3.1) mm Hg(1 mm Hg= 0.133 kPa), P<0.05], and SOD activity in LIPER group was significantly increased[(33.78±2.06) vs.(14.21± 1.14) U/mg, P< 0.05]. Conclusion Limbs ischemic preconditioning can attenuate the lung ischemiareperfusion injury in rats. Key words: Lung injury; Lung ischemia; Reperfusion injury; Limbs ischemic perconditioning