Extent Of Ischemia-reperfusion Injury Research Articles

Oxidative stress markers, thioredoxin 1 and 8-isoprostane, in relation to ischemic time in patients with ST‑segment elevation myocardial infarction treated by primary percutaneous coronary intervention.

The extent of ischemia-reperfusion injury (IRI) significantly affects the prognosis of patients with ST-segment elevation myocardial infarction (STEMI). Excessive generation of reactive oxygen species during ischemia and subsequent reperfusion leads to cellular necrosis and apoptosis. These processes contribute to the impairment of microcirculation and the no-reflow phenomenon, development and progression of left ventricular remodeling and failure. Out of numerous factors affecting the complex process of IRI, the duration of ischemia is of major importance. Prolonged ischemia has been associated with higher degree of oxidative stress, but only scarce evidence is available up to date.2 Our goal was to evaluate selected markers of oxidative stress in relation to reperfusion via primary percutaneous coronary intervention (pPCI) and their potential correlation with the duration of ischemia, defined as time delay between symptom onset and reperfusion.

Hypothermic Oxygenated Machine Perfusion of Extended Criteria Kidney Allografts from Brain Dead Donors: Protocol for a Prospective Pilot Study.

BackgroundKidney transplantation is the only curative treatment option for end-stage renal disease. The unavailability of adequate organs for transplantation has resulted in a substantial organ shortage. As such, kidney donor allografts that would have previously been deemed unsuitable for transplantation have become an essential organ pool of extended criteria donor allografts that are now routinely being transplanted on a global scale. However, these extended criteria donor allografts are associated with significant graft-related complications. As a result, hypothermic oxygenated machine perfusion (HOPE) has emerged as a powerful, novel technique in organ preservation, and it has recently been tested in preclinical trials in kidney transplantation. In addition, HOPE has already provided promising results in a few clinical series of liver transplantations where the liver was donated after cardiac death.ObjectiveThe present trial is an investigator-initiated prospective pilot study on the effects of HOPE on extended criteria donor allografts donated after brain death and used in kidney transplantation.MethodsA total of 15 kidney allografts with defined inclusion/exclusion criteria will be submitted to two hours of HOPE via the renal artery before implantation, and are going to be compared to a case-matched group of 30 patients (1:2 matching) who had kidneys transplanted after conventional cold storage. Primary (posttransplant dialysis within 7 days) and secondary (postoperative complications, early graft function, duration of hospital and intensive care unit stay, and six-month graft survival) endpoints will be analyzed within a six-month follow-up period. The extent of ischemia-reperfusion injury will be assessed using kidney tissue, perfusate, and serum samples taken during the perioperative phase of kidney transplantationResultsThe results of this trial are expected in the first quarter of 2020 and will be presented at national and international scientific meetings and published in international peer-reviewed medical journals. The trial was funded in the third quarter of 2017 and patient enrollment is currently ongoing.ConclusionsThis prospective study is designed to explore the effects of HOPE on extended criteria donor kidney allografts donated after brain death. The present report represents the preresults phase.Trial RegistrationClinicaltrials.gov NCT03378817; https://clinicaltrials.gov/ct2/show/NCT03378817

359 Combinatorial Surgical and Neuroprotective Therapy for Cervical Spondylotic Myelopathy Results in Improved Neurological Function

Abstract INTRODUCTION Surgical decompression is an effective treatment for cervical spondylotic myelopathy (CSM). However, a number of patients continue to experience substantial neurological impairment post surgery. Riluzole has neuroprotective effects in injuries of the central nervous system. To determine the efficacy of riluzole for promoting neurological improvement in CSM following decompression, we performed a pre-clinical proof of concept experiment and then we translated our work and established a Phase III multi-center randomized controlled clinical trial (CSM-Protect). METHODS Surgical decompression was performed in a rat CSM model and riluzole, or control, was administered. Spinal cord blood flow (SCBF) was evaluated in all CSM rats, in vivo, before and after decompression using FAIR MRI. The long-term outcomes of decompression with or without riluzole treatment determined using neurobehavioural and neuroanatomical assessments. Our multi-center double-blind randomized CSM-Protect trial includes a total of 300 CSM patients undergoing decompression surgery and randomized 1:1 to receive riluzole (2 × 50 mg daily for 14 days before and 28 days post surgery) or placebo treatment. MJOA score will determine the effectiveness of the combinatorial treatment at 6 months following surgery. Statistical analysis will be performed as a sequential adaptive trial with interim analysis. RESULTS >Rats receiving combinatorial treatment displayed long-term significant neurological improvements associated with preservation of motor neurons and corticospinal tracts compared to rats treated with decompression alone. Riluzole also dramatically reduced the extent of ischemia-reperfusion injury post surgical decompression in our animal model. At present, 285 subjects have been enrolled into the CSM-Protect trial. A planned interim analysis using this sample has commenced. CONCLUSION The proposed combinatorial therapy promotes neurological recovery in CSM rats. Confirmation of this proof of concept has been translated from bench to the bedside and we are currently running the CSM-Protect trial to determine the efficacy of this combinatorial treatment option for use in CSM patients.

Liver steatosis in pre-transplant liver biopsies can be quantified rapidly and accurately by nuclear magnetic resonance analysis.

Donor livers marginally acceptable or acceptable according to extended criteria are more frequently transplanted due to the growing discrepancy between demand and availability of donor organs. One type of marginally acceptable graft is a steatotic donor liver, because it is more sensitive to ischemia-reperfusion injury. Thus, quantitative assessment of steatosis is crucial prior to liver transplantation. Extent of steatosis of 49 pre-reperfusion liver biopsies from patients who received orthotopic liver transplantation was assessed by three techniques: semi-quantitative histological evaluation, computerized histomorphometry, and NMR-based estimation of fat content. The findings were correlated to clinical data and to histological examination of corresponding post-reperfusion biopsies for quantification of ischemia-reperfusion injury. We found that values obtained through all three assessment methods were positively correlated. None of the values obtained by the three applied methods correlated with clinical outcome or extent of ischemia-reperfusion injury. Quantitative evaluation of steatosis by NMR yields results comparable to histological and morphometrical assessment. This technique is rapid (<5min), accurately quantifies fat in donor livers, and provides results that can be used when evaluation by a pathologist is not available.

Protective effects of recombinant human bone morphogenetic protein-7 on focal cerebral ischemia–reperfusion injury

This study was to investigate the protective effect of recombinant human bone morphogenetic protein-7 (rhBMP-7) on focal cerebral ischemia–reperfusion (IR) injuries and their underlying mechanisms. An intraluminal suture method was used to generate a middle cerebral artery occlusion model in rats, which was followed by reperfusion. A sham operation (SO) group underwent the procedure without occlusion, whereas an IR group and rhBMP-7 treated group (RT) underwent occlusion in the absence and presence of rhBMP-7 (250 μg/kg) administered via a femoral vein injection 30 minutes prior to reperfusion. Twenty-four hours after reperfusion, neurological function, brain water content and morphological alterations were examined. Apoptosis was detected using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assays, and immunohistochemical staining and Western blot assays were used to detect nuclear nuclear factor-kappa B (NF-κB) p65 expression. Compared with the SO group, IR rats showed a decrease in neurological function, an increase in brain water content, and pathological and morphological damage (p < 0.05). Higher levels of apoptosis were also detected in the infarct region area. In contrast, RT rats had reduced injury after IR. In addition, while immunohistochemical staining and western blot assays consistently detected increased expression of nuclear NF-κB after IR, these levels were reduced in the RT group. Administration of rhBMP-7 prior to reperfusion effectively inhibited the extent of IR injury by attenuating cerebral edema and ameliorating ultrastructural damage. The underlying mechanisms responsible for these observations potentially involve the inhibition of apoptosis induced by IR by rhBMP-7 via an NF-κB-related signaling cascade.

Extracellular purines serve as an innate trigger to allograft rejection (145.39)

Abstract Innate immune triggers are well studied in infectious models, yet they remain unclear in solid organ transplantation. Extracellular purines (e.g. ATP, adenosine), which signal through receptors on immune cells, modulate the extent of ischemia reperfusion injury. To test the effect of purinergic signaling on graft rejection, we used a cardiac transplant model in outbred mice in which accelerated graft rejection occurs within 4 days post-transplantation and is highly dependent on innate mediators. Treatment with NECA, an adenosine receptor agonist, 2 hours prior to heterotopic heart transplantation (n=8) completely abrogated accelerated rejection compared to untreated outbred mice (incidence = 28%, n=35). CD39 and CD73 are ectoenzymes responsible for metabolism of extracellular ATP to adenosine. To determine the effect of increased extracellular ATP in the local graft environment, hearts from CD73-deficient B6 mice were transplanted to BALB/c recipients. Accelerated rejection occurred in 24% of grafts from CD73-/- mice (n=17) compared to 2% of grafts from wt inbred controls (n=42). Skin transplants from CD39-/- and CD73-/- mice to BALB/c mice (n=8/group) rejected at the same rate as wt control B6 to BALB/c skin transplants (n=8), suggesting the effect was restricted to vascularized transplants. Our data suggests that modulation of purine metabolism serves as an early trigger of the innate immune response in vascularized organ transplantation.

Importance of Real-Time Tissue Oximetry: Relationship to Muscle Oxygenation and Tissue Viability

There is currently no efficient and reliable clinical means of assessing the degree of ischemia- and reperfusion-associated damage in microvascular transplants. The objective was to study correlation of tissue oxygen tension measurements with tissue oxygen saturation, cytochrome oxidase redox state, and tissue viability. Latissimus dorsi muscle was dissected and mobilized in New Zealand white rabbits (n = 30, 2.5 ± 0.5 kg). Muscles were exposed to warm ischemia in two groups with either 4 or 6 h, followed by reperfusion. Tissue PO(2) was measured with a miniature intramuscular oxygen sensor (Licox microprobe; Integra Neurosciences, Ratingen, Germany) all along with tissue hemoglobin saturation (rSO(2)) and cytochrome oxidase aa3 redox state (CytOx) by in vivo near-infrared spectroscopy. Linear correlation was performed between tissue PO(2) and rSO(2), CytOx and tissue viability. After ischemia and reperfusion, tissue PO(2) and CytOx recovery was significantly decreased in both groups compared with control (4 h: P < 0.05; 6 h: P < 0.01). Significant correlations between changes in tissue PO(2) and rSO(2) (r = 0.92; P < 0.01), CytOx (r = 0.90; P < 0.01), wet-to-dry ratio (r = -0.97; P < 0.01), and mitochondrial viability index (r = 0.97; P < 0.01) were found. Tissue oxygen tension measured with microprobes correlated closely with tissue oxygenation, cellular oxygen utilization, and the extent of ischemia reperfusion injury.

Management of traumatic brachial artery injuries: A report on 49 patients

BACKGROUND AND OBJECTIVE:The brachial artery is the most frequently injured artery in the upper extremity due to its vulnerability. The purpose of our study was to review our experience with brachial artery injuries over a 9-year period, describing the type of injury, surgical procedures, complications, and associated injuries.PATIENTS AND METHODS:Forty-nine patients with brachial artery injury underwent surgical repair procedures at our hospital, from the beginning of May 1999 to the end of June 2008. The brachial artery injuries were diagnosed by physical examination and Doppler ultrasonography. Depending on the mode of presentation, patients were either taken immediately to the operating room for bleeding control and vascular repair or were assessed by preoperative duplex ultrasonography.RESULTS:This study group consisted of 43 males and 6 females, ranging in age from 6 to 65 years with a mean (SD) age of 27.9 (6.7) years. The mechanism of trauma was penetrating in 45 patients and blunt in the remaining 4 patients. Stab injury was the most frequent form of penetrating trauma (24 of 45). Treatment included primary arterial repair in 5 cases, end-to-end anastomosis in 28 cases, interposition vein graft in 15 cases, and interposition-ringed polytetrafluoroethylene graft in 1 case. Associated injuries were common and included venous injury (14), bone fracture (5), and peripheral nerve injury (11). Fifteen patients developed postoperative complications. One patient underwent an above-elbow amputation.CONCLUSIONS:Prompt and appropriate management of the brachial artery injuries, attention to associated injuries, and a readiness to revise the vascular repair early in the event of failure will maximize patient survival and upper extremity salvage.

Intrahepatic expression and release of vascular endothelial growth factor following orthotopic liver transplantation in the rat.

Morphological and functional changes to sinusoidal endothelial cells mediated by soluble factors released from activated Kupffer cells, including cytokines, are considered pivotal events in ischemia/reperfusion injury (IRI) to liver grafts. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific cytokine with potent pro-inflammatory and mitogenic effects. We investigated the possible role of VEGF in IRI to liver grafts using a syngeneic rat orthotopic liver transplantation model. Transplantation was performed in Lewis rats using livers preserved for various periods of time (24-48 hr) in University of Wisconsin solution at 4 degrees C. Systemic VEGF levels were measured by enzyme-linked immunosorbent assay (ELISA). Intrahepatic VEGF expression was analyzed by Northern blotting and in situ hybridization. The effects of anti-VEGF neutralizing antibody treatment on the extent of IRI were assessed by measuring liver function tests, lipid peroxidation, and metalloproteinase activity. VEGF is expressed and released in a biphasic pattern during the early postoperative period after liver transplantation. Anti-VEGF antibody treatment, administered during reperfusion, decreased the degree of damage, suggesting that VEGF may have a role in IRI to liver grafts.

Soluble ICAM-1 reduces leukocyte adhesion to vascular endothelium in ischemia-reperfusion injury in mice.

Ischemia-reperfusion injury is a pathogenic factor in the course of many clinical disorders, such as myocardial infarction, stroke, organ transplantation, burns, and circulatory shock. The extent of ischemia-reperfusion injury is dependent on the number of infiltrating leukocytes. With in vivo microscopy, we evaluated the effect of the recombinant form of soluble murine intercellular adhesion molecule-1 (ICAM-1) on ischemia-reperfusion injury in an animal model. A mesenteric vein was occluded with a clamp for 45 min. During a reperfusion period of 30 min, the number of leukocytes rolling along the endothelium and the number of adherent leukocytes were measured with and without pretreatment with recombinant ICAM-1. The number of leukocytes rolling along the endothelial surface increased more than twofold during postischemic perfusion (P < 0.05). Recombinant ICAM-1 had no effect on leukocyte rolling. In the control group, firm adherence of leukocytes was increased 10-fold. Recombinant ICAM-1 dose dependently reduced firm adhesion to the endothelium in response to prior ischemia. After 30 min, reperfusion pretreatment with recombinant ICAM-1 inhibited leukocyte adherence from 512 +/- 123 to 166 +/- 34 leukocytes/mm2 (P < 0.01). We demonstrate here for the first time that soluble recombinant ICAM-1 is able to reduce leukocyte adherence to mesenteric venules in postischemic reperfusion injury dose dependently. Because soluble ICAM-1 is naturally circulating in human serum, the therapeutic use of soluble recombinant forms of ICAM-1 may represent a physiological way to protect against ischemiareperfusion injury.

Relation between myocardial glutathione content and extent of ischemia-reperfusion injury.

The relation between the extent of myocardial injury sustained during reperfusion and total glutathione (GSH) content in the ischemic myocardium was examined in anesthetized open-chest pigs subjected to coronary occlusion for 45 minutes and reperfusion for 2 hours. In pigs infused with saline during reperfusion (n = 6) there was a decrease in myocardial GSH content from 380 +/- 48 micrograms/g in normally perfused myocardium to 182 +/- 36 micrograms/g in the ischemic reperfused myocardium (p less than 0.02). Myocardial infarct size (expressed as a percentage of the ischemic area) was 12.5 +/- 0.8%. There was a delay of recovery of contractile function before returning to 60% of preocclusion value. In pigs pretreated with buthionine sulfoximine (BSO) (n = 5), an inhibitor of cellular GSH synthesis, there was reduction in GSH content to 215 +/- 25 micrograms/gm in normally perfused myocardium and to 77 +/- 8 micrograms/gm in the ischemic reperfused myocardium. The extent of injury was greater as evidenced by an increase in infarct size to 30.4 +/- 4.0% (p less than 0.001), severe destructive changes in subepicardial ultrastructure, which were absent in saline-infused pigs, and persistence of dyskinesia throughout reperfusion. In pigs infused with glutathione intravenously (0.8 gm/kg) at a rate of 6.5 mg/kg/min (n = 6), 5 minutes before and continuously during reperfusion, there was an increase in GSH content to 582 +/- 67 micrograms/g in normally perfused myocardium and to 312 +/- 80 micrograms/g in ischemic reperfused myocardium. The increase in myocardial GSH was associated with a reduction in infarct size to 7.5 +/- 1.3% (p less than 0.05, compared with saline-infused pigs) and an early recovery of contractile function of the ischemic myocardium. GSH infusion into pigs pretreated with BSO (n = 4) failed to increase myocardial GSH content and failed to reduce the extent of myocardial injury. Thus, the extent of myocardial injury sustained during reperfusion is very dependent on the effectiveness of its antioxidant defenses. Markedly increased susceptibility to injury occurs when the GSH content in the ischemic myocardium becomes depleted.

Correlation between myocardial glutathione content and extent of ischemia-reperfusion injury

Considerable evidence suggests that myocardial injury may occur during reperfusion of the ischemic myocardium. Reactive oxygen species are generated during reperfusion which may play an important role in the genesis of myocardial reperfusion injury. Glutathione (GSH) is an important antioxidant in the heart. A decrease in myocardial GSH content has been observed during ischemia and reperfusion of the ischemic myocardiijm. We hypothesized that this depletion of GSH may be detrimental to the ability of the ischemic myocardium to protect itself against reactive oxygen species during reperfusion.In this study, anesthetized open chest pigs were subjected to coronary occlusion for 45 minutes and 2 hours reperfusion. Myocardial GSH was experimentally depleted by pretreatment with buthionine sulfoximine (BSO), a potent inhibitor of cellular GSH synthesis, and was augmented by intravenous administration of GSH. For ultrastructural study multiple subepicardial biopsies 3 mm deep were taken from myocardium supplied by the occluded artery. The biopsies were processed by routine procedures. Thin sections were stained with uranyl acetate and lead citrate and examined with a Philip EM 300 electron microscope.