PostC Group Research Articles

MiR-144-5p/CCL12 Signaling Axis Modulates Ischemic Preconditioning-Mediated Cardio-protection by Reducing Cell Viability, Enhancing Cell Apoptosis, Fibrosis, and Pyroptosis.

Ischemic postconditioning (IPost) represents short periods of nonlethal ischemia-reperfusion performed at the onset of reperfusion. Studies have shown that IPost involves various biological processes such as cell proliferation, apoptosis, and pyroptosis and can activate complex signaling pathways. CCL12 is a critical mediator in the inflammatory process after tissue injury. In the present study, we examined the potential actions of CCL12-mediated signaling pathways in cardioprotection after IPost using a cardiomyocyte model. By applying the bioinformatics analysis, we found that CCL12 was upregulated in the rat heart tissues after I/R injury, and the expression level of CCL12 was restored in rats with IPost. The in vitro studies showed that CCL12 and CCR2 expression levels were upregulated in the hypoxia/reoxygenation (H/R)-induced H9C2 cells, which was attenuated in the H/R + hypoxia post-conditioning (PostC) group. The functional assays showed that H/R treatment reduced cell viability, increased cell apoptosis, and promoted fibrosis and pyroptosis of H9C2 cells, which was attenuated in the H/R + PostC group. Overexpression of CCL12 impaired the protective action of hypoxia post-conditioning in the H9C2 cells. Further mechanistic studies showed that miR-144-5p could directly target the 3'untranslated region of CCL12. Overexpression of miR-144-5p markedly repressed the expression levels of CCL12 and CCR2 in H9C2 cells, while miR-144-5p inhibition had the opposite effects. Furthermore, the inhibition of miR-144-5p reduced the cell viability, increased cell apoptosis, and enhanced fibrosis and pyroptosis of H9C2 cells after H/R or H/R + PostC treatment. In conclusion, CCL12 was downregulated in cardiomyocytes following ischemic postconditioning, and CCL12 overexpression impaired the cardioprotective actions of ischemic postconditioning by reducing cell viability, enhancing cell apoptosis, fibrosis, and pyroptosis. Further mechanistic evidence revealed that CCL12 was a direct target of miR-144-5p, and miR-144-5p/CCL12/CCR2 signaling may represent a critical pathway in mediating the cardioprotective effects of ischemic postconditioning.

Creating a Chest Wall Injury and Reconstructive program: A single center experience with rib fractures

BackgroundNew Chest Wall Injury and Reconstructive Centers (CWIRC) are emerging; this study aims to investigate the potential benefits of implementing a CWIRC at a single institution. We hypothesized that patients treated at CWIRC will have improved outcomes. MethodsWe instituted a CWIRC in 2019 at our American College of Surgeons (ACS) Level One Trauma Center. We retrospectively compared trauma patients with rib fractures who presented to our center 18 months before (PRE-C) and 18 months after CWIRC implementation (POST-C). Outcomes measured included mortality, length of stay (LOS), intensive care unit (ICU-LOS), readmission rates, and unplanned ICU admission. ResultsThere were 192 PRE-C patients, compared to 388 POST-C. The mortality in PRE-C was not significantly different compared to the POST-C group (11.46% vs 8.8%, p=0.308). There were also no differences in LOS, ICU-LOS, readmission, and unplanned ICU admission. ICU utilization was dramatically different: PRE-C 17.8% were admitted to ICU compared to 35.6% POST-C (p<0.0001). ConclusionsThe number of patients admitted with rib fractures to our center nearly doubled after CWIRC establishment. Early diagnosis and triage led to significantly more admissions to higher levels of care. There are trends toward improved outcomes using practice management protocols, albeit with higher ICU utilization. Establishment of a CWIRC should be considered for level 1 ACS trauma centers and as utilization of established CWIRC protocols are increased, patients will have improved outcomes. Level of EvidenceIV Study TypeRetrospective chart review.

COVID-19 Pandemisinde Acil Servise Başvuran Üst Gastrointestinal Kanamalı Hastaların Sayısı Azaldı mı?: Tek Merkez Deneyimi

Objective: In the period of the coronavirus disease-19 (COVID-19) pandemic, upper gastrointestinal endoscopy was either postponed or canceled, except for emergencies, due to the high risk of transmission. Our study aimed to evaluate the effect of the COVID-19 pandemic on patients with upper gastrointestinal bleeding presenting to the emergency department and to compare it with the data before the pandemic. Material and Methods: In this single-center, retrospective study, patients were divided into 2 groups: pre-COVID-19 (pre-C) (March 2019-March 2020) and post-COVID-19 (post-C) (March 2020- March 2021). Patients who presented to the emergency department with upper gastrointestinal bleeding during these periods and underwent endoscopic examination were included in the study. Results: Endoscopy for upper gastrointestinal bleeding was urgently performed in 125 patients in the pre-C period and in 89 (29% decrease) patients in the post- C period. The Glasgow-Blatchford Score was higher in the pre-C period (p=0.02). Peptic ulcers were the most common cause of bleeding in both groups. High-risk peptic ulcer (forrest 1a/1b/2a/2b), and malignancy were observed more frequently in the post-C period (p=0.003, p=0.04; respectively). Endoscopic combined treatment rate was higher in the post-C group (p<0.001). Re-bleeding ratios were similar for both the groups (p=0.48). Conclusion: During the post-C period, the number of upper gastrointestinal bleeding cases admitted to the emergency department decreased significantly. However, the rate of high-risk peptic ulcer and malignancy in the etiology of upper gastrointestinal bleeding increased in the post-C period.

Hematological, Micro-Rheological, and Metabolic Changes Modulated by Local Ischemic Pre- and Post-Conditioning in Rat Limb Ischemia-Reperfusion.

In trauma and orthopedic surgery, limb ischemia-reperfusion (I/R) remains a great challenge. The effect of preventive protocols, including surgical conditioning approaches, is still controversial. We aimed to examine the effects of local ischemic pre-conditioning (PreC) and post-conditioning (PostC) on limb I/R. Anesthetized rats were randomized into sham-operated (control), I/R (120-min limb ischemia with tourniquet), PreC, or PostC groups (3 × 10-min tourniquet ischemia, 10-min reperfusion intervals). Blood samples were taken before and just after the ischemia, and on the first postoperative week for testing hematological, micro-rheological (erythrocyte deformability and aggregation), and metabolic parameters. Histological samples were also taken. Erythrocyte count, hemoglobin, and hematocrit values decreased, while after a temporary decrease, platelet count increased in I/R groups. Erythrocyte deformability impairment and aggregation enhancement were seen after ischemia, more obviously in the PreC group, and less in PostC. Blood pH decreased in all I/R groups. The elevation of creatinine and lactate concentration was the largest in PostC group. Histology did not reveal important differences. In conclusion, limb I/R caused micro-rheological impairment with hematological and metabolic changes. Ischemic pre- and post-conditioning had additive changes in various manners. Post-conditioning showed better micro-rheological effects. However, by these parameters it cannot be decided which protocol is better.

Comparative Analysis of Peri-Operative Parameters in Unstable Hip Fracture Management by PFNA: Hip Fracture Needs Early Care during Covid-19

Unstable peri-trochanteric fracture presents management challenges, more so during the Covid-19 pandemic. Aim of the study was to evaluateperi-operative parameters during proximal femoral anti-rotation (PFNA) nailing in the early lockdown period of Covid-19 pandemic (Post-C group) and compare them to a cohort of demographically matched unstable peri-trochanteric fracture group from the pre-lockdown period (Pre-C group) to ascertain any significant change in clinical, radiological and functional outcomes. We retrospectively analysed matched groups with respect to median age, ASA grading and comorbidities. Intraoperative parameters assessed were duration of operation theatre and surgical time for PFNA. In Post-C group, personal protection equipment (PPE) use by Health Care Worker (HCW)was evaluated.

IMPACTO DE LA PANDEMIA POR COVID-19 EN LA EPIDEMIOLOGÍA, MANEJO Y SUPERVIVENCIA DE LOS PACIENTES CON FRACTURA DE CADERA

The COVID-19 pandemic has forced a reorganization of health resources towards the care of patients with severe respiratory syndrome. While the incidence of traumatic pathology was reduced, this was not the case with hip fractures, and their management could be compromised. The objective of this study is to evaluate the consequences of the pandemic on the epidemiology, management and outcomes of hip fracture. Material and methods: A retrospective observational cohort study was done including patients with hip fracture treated between March 2019 and February 2021, establishing two groups for comparison, before and after the onset of the pandemic. Demographic variables, comorbidities, history of fragility fracture and hip fracture, type of fracture and type of treatment performed, surgical delay, length of hospital stay, and PCR result for SARS-CoV2 upon admission were recorded. In-hospital mortality rate and survival at 1 and 6 months were analyzed. Results: 251 patients were included, 137 (54.58%) PRE-COVID group and 114 (45.42%) POST-C group. There were no differences in demographic variables, comorbidities, type of fracture, or treatment performed. The absolute incidence was reduced by 16.8% and the relative incidence was reduced by 17.6%, this difference was significant during lockdown period and in the months o January and February, the period of maximum incidence of COVID-19. The incidence of PCR + on admission was 1.75%. No significant differences were found in surgical delay, hospital stay and mortality, survival at one month or at 6 months. Conclusion: With the COVID-19 pandemic, specific reductions in the incidence of hip fractures have been observed, without changes in its epidemiology, indicators of hospital management and in patient survival at one and 6 months.

Combined Intrahospital Remote Ischemic Perconditioning and Postconditioning Improves Clinical Outcome in ST-Elevation Myocardial Infarction.

Remote ischemic conditioning (RIC) or ischemic postconditioning (PostC) may protect the myocardium from ischemia-reperfusion injury in patients with ST-segment-elevation myocardial infarction. To determine whether combined intrahospital RIC and PostC or PostC alone in addition to primary percutaneous coronary intervention (PCI) reduce long-term clinical events after ST-segment-elevation myocardial infarction. The present study is a post hoc analysis of a prospective trial which randomized 696 ST-segment-elevation myocardial infarction patients with symptoms <12 hours 1:1:1 to either combined RIC and PostC in addition to primary PCI, PostC alone in addition to primary PCI, or conventional PCI (control). Three cycles of RIC were performed by inflation of an upper arm blood pressure cuff for 5 minutes followed by deflation for 5 minutes. PostC was performed after primary PCI via 4 cycles of 30 seconds balloon occlusions followed by 30 seconds of reperfusion. Major adverse cardiac events consisting of cardiac death, reinfarction, and new congestive heart failure were assessed during long-term follow-up. Follow-up data were obtained in 97% of patients in median 3.6 years after the index event (interquartile range, 2.9-4.2 years). Major adverse cardiac events occurred in 10.2% of patients in the combined RIC and PostC group and in 16.9% in the control group (odds ratio, 0.56; 95% CI, 0.32-0.97; P=0.04). The difference was driven by a significantly reduced rate of new congestive heart failure in the RIC and PostC group (2.7% versus 7.8%; odds ratio, 0.32; 95% CI, 0.13-0.84; P=0.02). In contrast, PostC alone did not reduce major adverse cardiac events compared with controls (14.1% versus 16.9%; odds ratio, 0.81; 95% CI, 0.48-1.35; P=0.41), and the reduction of new congestive heart failure was not statistically significant (3.5% versus 7.8%; odds ratio, 0.43; 95% CI, 0.18-1.03; P=0.05). Cardioprotection by combined intrahospital RIC and PostC in addition to primary PCI significantly reduced the rate of major adverse cardiac events and new congestive heart failure after ST-segment-elevation myocardial infarction. URL: http://www.clinicaltrials.gov . Unique identifier: NCT02158468.

Role of JNK signalling pathway and platelet‑lymphocyte aggregates in myocardial ischemia‑reperfusion injury and the cardioprotective effect of ischemic postconditioning in rats.

In myocardial ischemia‑reperfusion injury (MIRI), increased activity of the c‑Jun N‑terminal kinase (JNK) pathway and the activation of platelets that leads to the formation of platelet‑leukocyte aggregates (PLAs) have been observed. It was hypothesized that ischemic postconditioning in MIRI exerts cardioprotective effects by altering JNK activity, which in turn leads to reduced PLA levels. A total of 60 rats were randomly divided into 6 groups (n=10 for each group): i)Control; ii)ischemia‑reperfusion injury alone; iii)ischemia‑reperfusion with postconditioning (PostC group), iv)treatment with the JNK inhibitor‑SP600125; v)postC and treatment with anisomycin; and vi)treatment with the JNK activator‑anisomycin. Subsequently, the levels of PLA, infarct size, myocardial injury markers (creatinine kinase‑muscle/brain and troponin I) and were measured. Western blotting was used to determine the protein expression of phosphorylated‑JNK. MIRI led to increased myocardial infarct size that was associated with raised troponin I and creatine kinase‑muscle/brain. At different time points of MIRI, the level of PLA gradually increased. Compared with the injury‑reperfusion group, the level of PLA in the PostC and Inhibitor‑JNK groups was significantly reduced at 60min and 3h following reperfusion. MIRI was able to increase the expression of phosphorylated JNK. These effects were significantly reduced by ischemic postC or by treatment with SP600125. By contrast, the addition of anisomycin attenuated these protective effects. JNK is a critical mediator of MIRI. Ischemic postC can reduce the level of PLA during reperfusion by inhibiting the phosphorylation of JNK MAPK, thereby reducing MIRI. Pharmacological inhibition and activation of JNK can improve and reduce cardioprotective effects, respectively. These results explained the mechanism of the cardioprotection of postC and provided novel insight and target for the therapeutic strategy of MIRI.

High-fat diet abolishes the cardioprotective effects of ischemic postconditioning in murine models despite increased thioredoxin-1 levels.

Ischemic postconditioning (PostC) reduces infarct size in healthy experimental models. However, if protective effects of PostC are abolished during early stages of atherosclerotic and if this is related with a disbalance in mitochondrial energetics and alterations in thioredoxin-1 (Trx1) is still unknown. The objectives were to generate a murine high-fat diet (HFD)-fed model that developed in a phenotype consistent with early stages of atherosclerosis to then evaluate whether HFD exposure increased oxidative stress and consequently abolished the cardioprotection conferred by PostC. We used C57/BL6 mice fed with control diet (CD) or HFD for 12 weeks. Isolated mice hearts were subjected to 30min of ischemia and 120min of reperfusion (I/R group). For PostC group, after ischemia, six cycles of reperfusion/ischemia were performed (10s per cycle) at the onset of reperfusion. In CD group, the PostC reduced infarct size (CD-I/R: 52.14 ± 2.8 vs. CD-PostC: 36.58 ± 1.8, P < 0.05) and increased phosphorylation of GSK3β (CD-PostC: 2.341 ± 1.03 vs. CD-Baseline: 0.923 ± 0.41 AUOD, P < 0.05), and this cardioprotection was abolished in HFD-exposed mice. HFD increased hydrogen peroxidelevels, produced a shift towards an oxidized intracellular environment (GSSG/GSH2), and increased Trx1 expression with higher fractions of oxidized protein. State 3 mitochondrial oxygen consumption in basal conditions decreased 24% in HFD-exposed mice and PostC improved state 3 values only in CD mice. Cellular redox state and mitochondrial bioenergetics were altered in HFD-exposed mice. We demonstrated that alterations in redox state at early stages of atherosclerosis abolished cardioprotective mechanisms, such as those induced by PostC, even with increased Trx1 levels.

Neuroprotective Effects of Fasudil, a Rho-Kinase Inhibitor, After Spinal Cord Ischemia and Reperfusion in Rats.

Excessive Rho/Rho-kinase pathway activation occurs subsequent to stroke. We examined the neuroprotective effects of pre- and posttreatment with fasudil (a Rho-kinase inhibitor) in a rat transient spinal cord ischemia-reperfusion model under normothermic conditions. After approval by our animal research committee, male Sprague-Dawley rats were assigned to 1 of 6 groups: pre- and postcontrol (C); pre- and postfasudil (F); and pre- and postsham (S). Fasudil (10 mg/kg) or normal saline was administered intravenously over 30 minutes before ischemia in the pre-F or pre-C groups, and over 30 minutes after reperfusion in the post-F or post-C groups. Sham groups were not subjected to ischemia. Ischemia was induced by aortic occlusion using a balloon catheter combined with hypotension for 10 minutes. Neurologic deficit scores (NDS; 0-8 points) were assessed 1, 7, and 14 days after ischemia, and then histopathologic outcomes were assessed. NDS 7 and 14 days after ischemia in the pre-F group (median [range]; 3.5 [2-6] and 2.5 [0-6]) were lower than those in the pre-C group (5.5 [4-7] and 4.5 [4-6]; P = .046 and P = .049), whereas NDS in the post-F group and in the post-C group were not different. The numbers of intact neurons in the gray matter in the pre- and post-F groups (mean ± standard deviation [95% confidence interval]: 25 ± 7 [20-30] and 16 ± 5 [12-19]) were greater than those in the pre- and post-C groups (11 ± 5 [7-14] and 9 ± 3 [7-11]; P < .001 and P = .002). The number of intact neurons in the post-F group (16 ± 5 [12-19]) was lower than the number in the post-S group (26 ± 2 [24-29]; P < .001). The percentages of vacuolation in the white matter in the pre- and post-F groups (21.5 ± 8.4 [15.5-27.5] and 13.6 ± 7.4 [8.3-18.9]) were lower than those in the pre- and post-C groups (43.7 ± 10.4 [36.3-51.1] and 40.6 ± 12.3 [31.8-49.4]; P < .001 and P < .001). Our results demonstrated that intravenous fasudil administered before ischemia improved both neurologic and histopathologic outcomes even 14 days after ischemia, while fasudil administered postinsult improved histopathologic outcomes only in normothermic rats. Fasudil may be a relevant pretreatment paradigm for planned procedures at risk for spinal cord ischemia.

Optimized postconditioning algorithm protects liver graft after liver transplantation in rats

BackgroundIschemia reperfusion injury (IRI) causes postoperative complications and influences the outcome of the patients undergoing liver surgery and transplantation. Postconditioning (PostC) is a known manual conditioning to decrease the hepatic IRI. Here we aimed to optimize the applicable PostC protocols and investigate the potential protective mechanism. MethodsThirty Sprague–Dawley rats were randomly divided into 3 groups: the sham group (n = 5), standard orthotopic liver transplantation group (OLT, n = 5), PostC group (OLT followed by clamping and re-opening the portal vein for different time intervals, n = 20). PostC group was then subdivided into 4 groups according to the different time intervals: (10 s × 3, 10 s × 6, 30 s × 3, 60 s × 3, n = 5 in each subgroup). Liver function, histopathology, malondialdehyde (MDA), myeloperoxidase (MPO), expressions of p-Akt and endoplasmic reticulum stress (ERS) related genes were evaluated. ResultsCompared to the OLT group, the grafts subjected to PostC algorithm (without significant prolonging the total ischemic time) especially with short stimulus and more cycles (10 s × 6) showed significant alleviation of morphological damage and graft function. Besides, the production of reactive oxidative agents (MDA) and neutrophil infiltration (MPO) were significantly depressed by PostC algorithm. Most of ERS related genes were down-regulated by PostC (10 s × 6), especially ATF4, Casp12, hspa4, ATF6 and ELF2, while p-Akt was up-regulated. ConclusionsPostC algorithm, especially 10 s × 6 algorithm, showed to be effective against rat liver graft IRI. These protective effects may be associated with its antioxidant, inhibition of ERS and activation of p-Akt expression of reperfusion injury salvage kinase pathway.

Hypoxic postconditioning improves behavioural deficits at 6 weeks following hypoxic-ischemic brain injury in neonatal rats

Hypoxic-ischemic (HI) brain injury in newborns is associated with high morbidity and mortality, with many babies suffering neurological deficits. Recently, we showed that hypoxic postconditioning (PostC) immediately post injury can protect against HI up to one week in neonatal rats. Here, we aimed to examine whether long term functional deficits were also improved by PostC. Sprague-Dawley rats were assigned to control (C) or HI group on postnatal day 7 (P7). The HI group underwent unilateral carotid artery occlusion followed by hypoxia (7% oxygen, 3h). Half of each group were randomly assigned to the PostC group (8% oxygen, 1h/day for 5days post-injury), or normoxic group, where animals were kept under ambient conditions. Righting reflex and negative geotaxis tests were performed on P8 and P14. On P42, rats underwent further behavioural tests of motor function and memory (forelimb grip strength, grid walking and novel object recognition tasks). Brain injury was assessed using histological scoring of brain sections. At P14, PostC reduced the righting reflex deficit compared to HI alone. Long-term (6 weeks) behavioural deficits were observed in grid walking and novel object recognition tests after HI alone, with both functions improved following PostC. Following HI, there was an increase in brain injury assessed by histological scoring compared to control, and this damage was reduced by PostC. This novel finding of long-term histological neuroprotection accompanied by functional improvements by PostC further demonstrates the clinical potential of mild hypoxia for the treatment of HI brain injury.

Sevoflurane Attenuates Ischemia-Reperfusion Injury in a Rat Lung Transplantation Model

Sevoflurane is one of the most commonly used volatile anesthetic agents with the fastest onset and offset, replacing isoflurane in modern anesthesiology. Preconditioning and postconditioning using volatile anesthetics can attenuate ischemia-reperfusion injury (IRI). However, no previous studies have evaluated the effect of sevoflurane in lung transplantation after cold ischemic injury. We aimed to study the effects of donor and recipient treatment with sevoflurane in a rat lung transplantation model. Lewis rats were allocated to four groups: control, PreC (preconditioning), PostC (postconditioning), and PreC+ PostC. Donor rats in the PreC and PreC+PostC groups were exposed to 1.5% sevoflurane for 30 minutes before donor operation. Donor lungs were flushed with Perfadex and stored for 12 hours at 4°C before transplantation. Recipients received orthotopic left lung transplantation. In the PostC and PreC+ PostC groups, sevoflurane was initiated 2 minutes before reperfusion and maintained for 30 minutes. Two hours after reperfusion, lung function was evaluated, and samples were collected for histologic, inflammatory, and cell death assessment. Preconditioning and postconditioning using sevoflurane significantly improved the oxygenation of lung grafts (partial arterial gas pressure of oxygen: 198mm Hg in control, 406.5 mm Hg in PreC, 472.4 mm Hg in PostC, and 409.7 mm Hg in PreC+ PostC, p < 0.0001) and reduced pulmonary edema. Sevoflurane treatment reduced levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α. Moreover, sevoflurane significantly inhibited apoptotic cells by a decrease in cytochrome c release into cytosol and caspase-3 cleavage. Preconditioning or postconditioning of lungs using sevoflurane exhibits a significant protective effect against early phase of ischemia-reperfusion injury in a rat lung transplantation model.

Inhibition of endogenous thioredoxin-1 in the heart of transgenic mice does not confer cardioprotection in ischemic postconditioning

Thioredoxin-1 maintains the cellular redox status and decreases the infarct size in ischemia/reperfusion injury. However, whether the increase of thioredoxin-1 expression or its lack of activity modifies the protection conferred by ischemic postconditioning has not been yet elucidated. The aim was to evaluate if the thioredoxin-1 overexpression enhances the posctconditioning protective effect, and whether the lack of the activity abolishes the reduction of the infarct size. Wild type mice hearts, transgenic mice hearts overexpressing thioredoxin-1, and a dominant negative mutant (C32S/C35S) of thioredoxin-1 were used. The hearts were subjected to 30min of ischemia and 120min of reperfusion (Langendorff) (I/R group) or to postconditioning protocol (PostC group). The infarct size in the Wt-PostC group decreased in comparison to the Wt-I/R group (54.6±2.4 vs. 39.2±2.1%, p<0.05), but this protection was abolished in DN-Trx1-PostC group (49.7±1.1%). The ischemia/reperfusion and postconditioning in mice overexpressing thioredoxin-1 reduced infarct size at the same magnitude (35.9±2.1 and 38.4±1.3%, p<0.05 vs. Wt-I/R). In Wt-PostC, Trx1-I/R and Trx1- PostC, Akt and GSK3β phosphorylation increased compared to Wt-I/R, without changes in DN-Trx1 groups. In conclusion, given that the cardioprotection conferred by thioredoxin-1 overexpression and postconditioning, is accomplished through the activation of the Akt/GSK3β survival pathway, no synergic effect was evidenced. Thioredoxin-1 plays a key role in the postconditioning, given that when this protein is inactive the cardioprotective mechanism was abolished. Thus, diverse comorbidities or situations modifying the thioredoxin activity, could explain the absence of this strong mechanism of protection in different clinical situations.

Postischemic conditioning does not reduce muscle injury after tourniquet-induced ischemia-reperfusion injury in rats

BackgroundThe widespread application of tourniquets has reduced battlefield mortality related to extremity exsanguinations. Tourniquet-induced ischemia-reperfusion injury (I/R) can contribute to muscle loss. Postischemic conditioning (PostC) confers protection against I/R in cardiac muscle and skeletal muscle flaps. The objective of this study was to determine the effect of PostC on extremity muscle viability in an established rat hindlimb tourniquet model. MethodsRats were randomly assigned to PostC-1, PostC-2, or no conditioning ischemic groups (n = 10 per group). Postischemic conditioning, performed immediately after tourniquet release, consisted of four 15-second cycles (PostC-1) or eight 15-second cycles (PostC-2) of alternating occlusion and perfusion of hindlimbs. Twenty-four hours later, muscles were excised. The primary end points were muscle edema and viability; secondary end points were histologic and markers of oxidative stress. ResultsIschemia-reperfusion injury decreased viability in all tourniquet limbs, but viability was not improved in either PostC group. Likewise, I/R resulted in substantial muscle edema that was not reduced by PostC. The predominant histologic feature was necrosis, but no significant differences were found among groups. Markers of oxidative stress were increased similarly among groups after I/R, although myeloperoxidase activity was significantly increased only in the no conditioning ischemic group. A protective effect from PostC was not observed in our model suggesting that PostC was not effective in reducing I/R skeletal muscle injury or any benefits of PostC were not sustained for 24 hours when tissues were assessed. ConclusionThese negative findings are pertinent as the military investigates different strategies to extend the safe time for tourniquet application.

Ischemic postconditioning confers cardioprotection and prevents reduction of Trx-1 in young mice, but not in middle-aged and old mice.

Thioredoxin-1 (Trx-1) is part of an antioxidant system that maintains the cell redox homeostasis but their role on ischemic postconditioning (PostC) is unknown. The aim of this work was to determine whether Trx-1 participates in the cardioprotective mechanism of PostC in young, middle-aged, and old mice. Male FVB young (Y: 3month-old), middle-aged (MA: 12month-old), and old (O: 20month-old) mice were used. Langendorff-perfused hearts were subjected to 30min of ischemia and 120min of reperfusion (I/R group). After ischemia, we performed 6 cycles of R/I (10s each) followed by 120min of reperfusion (PostC group). We measured the infarct size (triphenyltetrazolium); Trx-1, total and phosphorylated Akt, and GSK3β expression (Western blot); and the GSH/GSSG ratio (HPLC). PostC reduced the infarct size in young mice (I/R-Y: 52.3±2.4 vs. PostC-Y: 40.0±1.9, p<0.05), but this protection was abolished in the middle-aged and old mice groups. Trx-1 expression decreased after I/R, and the PostC prevented the protein degradation in young animals (I/R-Y: 1.05±0.1 vs. PostC-Y: 0.52±.0.07, p<0.05). These changes were accompanied by an improvement in the GSH/GSSG ratio (I/R-Y: 1.25±0.30 vs. PostC-Y: 7.10±2.10, p<0.05). However, no changes were observed in the middle-aged and old groups. Cytosolic Akt and GSK3β phosphorylation increased in the PostC compared with the I/R group only in young animals. Our results suggest that PostC prevents Trx-1 degradation, decreasing oxidative stress and allowing the activation of Akt and GSK3β to exert its cardioprotective effect. This protection mechanism is not activated in middle-aged and old animals.

Cardioprotection by combined intrahospital remote ischaemic perconditioning and postconditioning in ST-elevation myocardial infarction: the randomized LIPSIA CONDITIONING trial.

Remote ischaemic conditioning (RIC) and postconditioning (PostC) are both potent activators of innate protection against ischaemia-reperfusion injury and have demonstrated cardioprotection in experimental and clinical ST-elevation myocardial infarction (STEMI) trials. However, their combined effects have not been studied in detail. The aim of this study was to evaluate if the co-application of intrahospital RIC and PostC has a more powerful effect on myocardial salvage compared with either PostC alone or control. This prospective, controlled, single-centre study randomized 696 STEMI patients to one of the following three groups: (i) combined intrahospital RIC + PostC in addition to primary percutaneous coronary intervention (PCI); (ii) PostC in addition to PCI; and (iii) conventional PCI (control). The primary endpoint myocardial salvage index was assessed by cardiac magnetic resonance (CMR) imaging within 3 days after infarction. Secondary endpoints included infarct size and microvascular obstruction (MVO) assessed by CMR. The combined clinical endpoint consisted of death, reinfarction, and new congestive heart failure within 6 months. The primary endpoint myocardial salvage index was significantly greater in the combined RIC + PostC group when compared with the control group (49 [interquartile range 30-72] vs. 40 [interquartile range 16-68], P = 0.02). Postconditioning alone failed to improve myocardial salvage when compared with conventional PCI (P = 0.39). The secondary endpoints, including infarct size and MVO, showed no significant differences between groups. Clinical follow-up at 6 months revealed no differences in the combined clinical endpoint between groups (P = 0.44). Combined intrahospital RIC + PostC in conjunction with PCI in STEMI significantly improves myocardial salvage in comparison with control and PostC. NCT02158468.

OP4 - Nitroglycerin-induced cardioprotection is endothelial nitric oxide synthase- dependent

Purpose We sought to evaluate the contribution of the endogenous NO pathway to the cardioprotective action of nitroglycerin (NTG). Methods and Results Anesthetized rabbits were subjected to 30-min myocardial ischemia (isc) and 3-h reperfusion (rep) and randomized into: Control group (no further intervention); PostC group (application of 8 cycles 30-sec isc/rep) and NTG treated group (2 μg/kg-1/min-1 IV bolus) for 65 min starting 10 min prior to rep. In additional groups, pharmacological inhibitors of NOS, nNOS, iNOS, PI3K, adenosine receptors and PKG were administrated with or without NTG. The infarcted (I) to risk (R) ratio was estimated. In a second experimental series tissue samples were collected from Control, PostC, NTG and NTG L-NAME groups in the 10th min of rep for determination of eNOS and Akt and of myocardial ROS-RNS by DHE staining, and nitrotyrosine and MDA levels evaluation. Inhibition of NOS or PI3K along with NTG eliminated the effect of NTG on %I/R (37.9±2.0%, and 38.3±2.6% respectively vs 23.0±3.2%, p

Influence of cardiovascular risk factors on infarct size and interaction with mechanical ischaemic postconditioning in ST-elevation myocardial infarction

ObjectivePrevious studies have shown that mechanical postconditioning (PostC) significantly reduces infarct size (IS) in patients with acute myocardial infarction. Our objective was to assess the influence of traditional cardiovascular (CV)...

Hypoxiс postconditioning is an effective method of protection from severe hypoxia induced lipid peroxidation and neuronal apoptosis in rats

Postconditioning (PostC) is an exposure of the damaged organism to extreme factors of the mild intensity to mobilize endogenous protective mechanisms. In our laboratory method of PostC using three daily trials of mild hypobaric hypoxia (MHH) was developed. It has been found that such method of the PostC effectively prevents degeneration of the hippocampal and neocortical neurons in rats, subjected to severe hypoxia (SH). Present study has been aimed at examination of the impact of oxidative processes in the development of the neuroprotection acquired in the course of hypoxic PostC during first three days of reoxygenation after SH in rats. The levels of thiobarbituric acid reactive substances (TBARS) and Schiff bases (SB) were used as markers of lipid peroxidation. In addition, the intensity of the apoptotic DNA fragmentation has been studied. During the three days after the SH a sustained increase of SB in the rat hippocampus was observed (700-1000% of the control value). After the first PostC episode the SB levels decreased to 150% of the baseline. Subsequently this parameter did not differ significantly from the control values. TBARS showed accumulation on the first day following the SH but afterwards its levels dropped to 40% of control and did not recover then to normal values. In the PostC animals, the levels of TBARS after each of three PostC episodes did not differ from the control values. These facts indicate that the PostC MHH balances the activity of pro- and antioxidant systems in vulnerable brain regions and promotes the effective utilization of components damaged by peroxidation. Fragments ladder typical for cells undergone apoptosis was obtained by the electrophoretic separation of the total DNA, extracted from a rat brain after one, two and three days after the SH. In the PostC group, the DNA fragmentation was revealed only after the first PostC episode, demonstrating antiapoptotic action PostC MHH.