Reperfusion Phase Research Articles

Novel Hemoglobin-Based Oxygen Carrier Bound With Albumin Shows Neuroprotection With Possible Antioxidant Effects

Background and Purpose- A hemoglobin-albumin cluster, 1 core of hemoglobin covalently bound with 3 shell albumins, designated as HemoAct was developed as a hemoglobin-based oxygen carrier. We aim to investigate neuroprotection by HemoAct in transient cerebral ischemia and elucidate its underlying mechanisms. Methods- Male rats were subjected to 2-hour transient middle cerebral artery occlusion and were then administered HemoAct transarterially at the onset of reperfusion. Neurological and pathological findings were examined after 24 hours of reperfusion to identify neuroprotection by HemoAct. Intermittent measurements of cortical blood flow and oxygen content were performed, and a histopathologic analysis was conducted on rats during the early phase of reperfusion to assess the therapeutic mechanism of HemoAct. In addition, the antioxidant effects of HemoAct were examined in hypoxia/reoxygenation-treated rat brain microvascular endothelial cells. Results- Neurological deterioration, infarct and edema development, and the activation of MMP-9 (matrix metalloprotease-9) and lipid peroxidation after 24 hours of reperfusion were significantly ameliorated by the HemoAct treatment. Reductions in blood flow and tissue partial oxygen pressure in the cortical penumbra after 6 hours of reperfusion were significantly ameliorated by the HemoAct treatment. The histopathologic analysis of the cortical penumbra revealed that HemoAct in HemoAct-treated rats showed superior microvascular perfusion with the mitigation of microvascular narrowing changes than autologous erythrocytes in nontreated rats. Although HemoAct extravasated into the ischemic core with serum protein, it did not induce an increase in serum extravasation or reactive oxygen species production in the ischemic core. In vitro experiments with rat brain microvascular endothelial cells revealed that HemoAct significantly suppressed cellular reactive oxygen species production in hypoxia/reoxygenation-treated cells, similar to albumin. Conclusions- HemoAct exerted robust neuroprotection in transient cerebral ischemia. Superior microvascular perfusion with an oxygen delivery capability and possible antioxidant effects appear to be the underlying neuroprotective mechanisms.

Liver Transplantation in Patient with Hereditary Hemorrhagic Telangiectasia or Rendu-Osler-Weber Disease

Introduction Hereditary hemorrhagic telangiectasia(HHT) is characterized by a disorder in vascular endothelium that presents angiodysplastic lesions in variuos organs. Their presence in the liver can cause serious and possibly mortal complications such as biliary ischemia, portal hypertension or cardiac insufficiency. The only definite cure for HHT with liver involvement is orthotopic liver transplantation(OLT) Materials and Methods 40y old woman is diagnosed with HHT type 2 in 2014. She presents with epistaxis, mucocutaneous telangiectasias, liver arteriovenous malformations(AVM), chronic hyperbilirubinemia and elevated cardiac output(12L/min) with hyperdynamic systolic function and pulmonary hypertension(PH). OLT is suggested as curative treatment. Before OLT her condition worsens and is unresponsive to medical treatment leading to numerous admissions due to decompensated heart failure(HF), GIT bleeding, respiratory infections and hepatic encephalopathy For OLT basic monitorization is carried out and pulmonary artery catheter is inserted before induction. The initial data shows moderate PH and hyperdynamic state. After the general anesthesia induction a transesophagel ultrasound is performed that shows moderate dilation of right cardiac chambers and hyperdynamic contraction function. During the hepatectomy there is moderate bleeding with signs of portal hypertension. During clamping of portal and suprahepatic veins there is no need for vasopressor medication. The hemodynamic changes and metabolic acidosis that occur in reperfusion phase are treated with epinephrine, ephedrine, calcium chloride and sodium bicarbonate. There was no postreperfusion syndrome. In the neohepatic phase norepinephrine infusion(up to 0.2mcg/kg/min) was initiated. The treatment with blood products was guided by ROTEM®. Lactic acid peaked at 8mmol/L and reached 6.9mmol/L at the time of transfer to the ICU.Results and discussion The worst complication in HHT patients with liver involvement is development of HF. That is due to presence of mayor shunts generated by AMV and that augment cardiac output by 25-58%. It is necessary to perform right cardiac catheterization preoperatively to assess pulmonary and right cardiac pressures and to evaluate the shunt and the contractile function. Possible treatments for the cardiopulmonary involvement are embolization or ligature of the hepatic artery, but with serious side effects such as liver necrosis or failure. The OLT should be considered at an early stage in patients with HHT with liver involvement to improve the cardiopulmonary function and avoid the risk for hepatobiliary sepsis and offer a better life quality. Conclusions The OLT is considered to be the only curative treatment for patients with HHT and liver involvement, especially when it is severe. It is important to perform an invasive cardiopulmonary assessment due to high possibility of secondary PH that will dictate the intraoperative anesthetic management.

Mitochondrial Damage-Associated Molecular Patterns (MTDs) Released from Hepatic Ischemia Reperfusion Induce Inflammatory Response

Background During liver transplantation ischemia and reperfusion injury (IRI), an immune driven inflammatory response provoked by cellular oxygen deprivation, is unavoidable. The inflammatory responses, resulting from acute oxidative stress and consequent hepatocellular death during the early reperfusion phase, cause the release of damage-associated molecular patterns. Recent studies show that the release of MTDs is directly linked with functionally important immune consequences and injury. We investigated the roles of MTDs in liver IRI. Methods Rat and human hepatocytes were used in the in vitro models, mice were used in an in vivo model of hepatic IR. Liver perfusate samples were obtained from porcine and human normothermic ex vivo liver perfusion (NMP) transplants from our collaborators and correlated to outcomes. MTDs were extracted and quantified by qPCR and PicoGreen assay. Liver biopsies were assayed by transmission electron microscopy (TEM) to assess for damaged mitochondria. MitoTracker was used to test the mitochondrial homeostasis by flow cytometry. The hepatocytes or macrophages were co-cultured with different concentrations of MTDs, and cell viability was demonstrated by apoptosis detection kit; the inflammatory cytokines (TNF-α, IL-6, and IL-1β) were tested by ELISA. Results The MTDs levels were significantly higher in IRI in vitro, and marked mitochondria damage was detected by TEM and flow cytometry. Co-culture of MTDs with hepatocytes significantly increased the cell death in a dose-dependent manner. Co-culture MTDs with macrophages significantly increased proinflammatory cytokine release via TLRs/MyD88 NF-κB pathway. The release of MTDs detected in vivo was associated with inflammatory cytokine secretion and more severe liver injury compared to the control. MTDs acted as an alarmin after hepatic IRI, which might contribute to the initiation of systemic inflammatory response. MTDs levels from pig DCD perfusate were higher than DBD perfusate samples in the pig NMP model, and higher level of MTDs were associated with worse clinical outcome in both the pig and human liver transplants following NMP. Conclusion Our results indicate that IRI can elicit a significant increase of MTDs both in vitro and in vivo, and that MTDs in ex vivo perfusates can be used as potential biomarkers of hepatic IRI and may predict outcomes after liver transplantation.

Reno-protective effects of TAK-242 on acute kidney injury in a rat model

Acute kidney inschemia/reperfusion (I/R) injury is characterized by an abrupt loss of kidney function, resulting in the retention of urea and other nitrogenous waste products and in the dysregulation of extracellular volume and electrolytes. Despite the advances in therapeutic techniques, the mortality and morbidity of patients remain high and have not appreciably improved. This study aims to evaluate the potential protective effect of TAK-242 on renal ischemia/reperfusion injury using an animal model. Thirty-five adult male Sprague-dawely rats (weighing 200–300), were assigned randomly into the following experimental groups (n = 7 in each group), Control (I/R), Sham (negative control), TAK-242 (5 mg/kg body weight), TAK-242 (10 mg/kg body weight) and Vehicle (DMSO). Rats were exposed to a 30 min of ischemia then 3 h of reperfusion. At the end of reperfusion phase, rats were sacrificed then plasma, serum and tissue samples were obtained to measure markers of kidney oxidative stress and inflammation. Plasma levels of neutrophil gelatinase-associated lipocalin (NGAL), and tissue levels of interleukin-18 (IL-18) and malondialdehyde (MDA) were significantly lower in TAK-242 pretreated groups than the vehicle group and the control group (p < 0.05). Furthermore; serum levels of urea and creatinine were significantly lower in the TAK-242 pretreated groups as compared to the control group (p < 0.05). We conclude that administration of TAK-242 can be useful preventive method in attenuating the degree of acute kidney injury during ischemic reperfusion process as shown by a significant reduction of urinary inflammatory markers as well as significant reduction of urea and creatinine levels.

Microcirculatory effects of sildenafil in experimental testicular torsion in rats.

Investigate the short-term effect of sildenafil on microcirculation, especially the velocity, the pattern of the flow and the recruitment of the leukocyte in postcapillaries. In male Sprague-Dawley rats, the microcirculatory consequences of 60min experimental testicular torsion, followed by 240min of reperfusion, were examined. Using fluorescence intravital microscopy, changes in red blood cell velocity in post-capillary venules and rolling as well as adhesion of leukocytes in the postcapillary venules were examined before the torsion and every hour during the reperfusion period. Sildenafil was given 10min prior to reperfusion (iv 0.7mg/kg, n = 6), while control animals received saline vehicle (n = 5). The characteristic flow motion disappeared in the affected testicular during the torsion. Red blood cell velocity values were dramatically decreased (by > 50%) and both rolling and adhesion of leukocytes increased during the reperfusion phase. Sildenafil treatment resulted in significantly higher red blood cell velocity values during the entire reperfusion period, but exerted only a temporary positive effect on the plost-ischaemic leukocyte-endothelial interactions. Intraoperative administration of sildenafil during surgical detorsion may provide marked testicular microperfusion benefits, but failed to influence the overall leukocyte-driven microcirculatory inflammatory reactions.

Negative feedback loop of autophagy and endoplasmic reticulum stress in rapamycin protection against renal ischemia-reperfusion injury during initial reperfusion phase.

Rapamycin, an immunosuppressant, is widely used in patients with kidney transplant. However, the therapeutic effects of rapamycin remain controversial. Additionally, previous studies have revealed deleterious effects of rapamycin predominantly when administered for ≥24 h. Few studies, however, have focused on the short-term effects of rapamycin administered only during the initial reperfusion phase. As such, we designed this study to explore the potential effects and mechanisms of rapamycin under a specific therapeutic regimen in which rapamycin is mixed in the perfusate during the initial reperfusion phase (within 24 h). Interestingly, we found that rapamycin maintained renal function and attenuated ischemia-reperfusion (I/R)-induced apoptosis in vivo and in vitro during the initial reperfusion phase, especially at 8 h after reperfusion. Simultaneously, rapamycin activated autophagy and inhibited endoplasmic reticulum (ER) stress and 3 pathways of unfolding protein response: ATF6, PERK, and IRE1α. Interestingly, we further found that the protective effects of rapamycin were suppressed when autophagy was inhibited by chloroquine and 3-methyladenine or when ER stress was induced by thapsigargin. Moreover, in terms of the regulatory effects of rapamycin, a negative-feedback loop between autophagy and ER stress occurred, with autophagy inhibiting ER stress and increased ER stress promoting autophagy during the initial reperfusion phase of renal I/R injury. Our study provides evidence that immediate reperfusion with rapamycin during the initial reperfusion phase repairs renal function and reduces apoptosis via activating autophagy, which could further inhibit ER stress. These results suggest a novel treatment modality for application during the initial reperfusion phase of renal I/R injury caused by kidney transplantation.-Li, X., Zhu, G., Gou, X., He, W., Yin, H., Yang, X., Li, J. Negative feedback loop of autophagy and endoplasmic reticulum stress in rapamycin protection against renal ischemia-reperfusion injury during initial reperfusion phase.

Critical Role of Flavin and Glutathione in Complex I-Mediated Bioenergetic Failure in Brain Ischemia/Reperfusion Injury.

Ischemic brain injury is characterized by 2 temporally distinct but interrelated phases: ischemia (primary energy failure) and reperfusion (secondary energy failure). Loss of cerebral blood flow leads to decreased oxygen levels and energy crisis in the ischemic area, initiating a sequence of pathophysiological events that after reoxygenation lead to ischemia/reperfusion (I/R) brain damage. Mitochondrial impairment and oxidative stress are known to be early events in I/R injury. However, the biochemical mechanisms of mitochondria damage in I/R are not completely understood. We used a mouse model of transient focal cerebral ischemia to investigate acute I/R-induced changes of mitochondrial function, focusing on mechanisms of primary and secondary energy failure. Ischemia induced a reversible loss of flavin mononucleotide from mitochondrial complex I leading to a transient decrease in its enzymatic activity, which is rapidly reversed on reoxygenation. Reestablishing blood flow led to a reversible oxidative modification of mitochondrial complex I thiol residues and inhibition of the enzyme. Administration of glutathione-ethyl ester at the onset of reperfusion prevented the decline of complex I activity and was associated with smaller infarct size and improved neurological outcome, suggesting that decreased oxidation of complex I thiols during I/R-induced oxidative stress may contribute to the neuroprotective effect of glutathione ester. Our results unveil a key role of mitochondrial complex I in the development of I/R brain injury and provide the mechanistic basis for the well-established mitochondrial dysfunction caused by I/R. Targeting the functional integrity of complex I in the early phase of reperfusion may provide a novel therapeutic strategy to prevent tissue injury after stroke.

The SAFE pathway is involved in the postconditioning mechanism of oxytocin in isolated rat heart

Oxytocin (OT) has a postconditioning effect against the ischemia-reperfusion (I/R) injury. However, its precise cardioprotection mechanism at the early reperfusion phase remains under debate. Our previous study revealed that OT postconditioning (OTpost) is cardioprotective by activating the Reperfusion Injury Salvage Kinase (RISK) pathway. Therefore, the present study is aimed to determine the biological effects of OTpost via the OT receptor and the activation of the JAK/STAT3 signaling pathway, mitochondrial adenosine triphosphate-dependent potassium channel (mitoKATP), nitric oxide (NO) release, and its anti-apoptotic effects against I/R injury in an isolated rat heart model.Sixty-three rats were randomly allocated to one of nine groups. OT was perfused 40 min prior to the regional ischemia or 15 min at the early reperfusion phase. AG490 (a JAK/STAT3 inhibitor), 5HD (a mitoKATP blocker), atosiban (an OT receptor antagonist), L-NAME (a nonspecific nitric oxide synthase inhibitor) were applied either alone or in combination with OT during the pre-ischemia phase and/or in the early reperfusion phase. Myocardial infarct size, hemodynamic factor, ventricular arrhythmia, coronary flow, cardiac biochemical marker, and the apoptosis index were determined at the end of reperfusion.Oxytocin postconditioning reduced infarct size, lactate dehydrogenase activity, arrhythmia score, ventricular fibrillation, and apoptosis. Moreover, AG490, 5HD, atosiban, and L-NAME abrogated the cardioprotective effects of OT.Our results demonstrated that the cardioprotective effects of OT are mediated by NO release, and the activation of mitoKATP and the SAFE pathway through the JAK/STAT3 signaling cascade that finally lead to decrease in the apoptosis index during the early reperfusion phase.

Impairment of renal organic anion transport mediated by organic anion transporter 1 (Oat1) and 3 (Oat3) in acute myocardial ischemic and reperfusion injury in rats

Acute kidney injury (AKI) is frequently associated with acute myocardial infarction (AMI). Kidney plays a crucial role in the clearance of uremic toxins, produced from organ dysfunctions, mainly through organic anion transporters 1 (Oat1) and 3 (Oat3). This study aims to examine the effects of acute myocardial ischemia and ischemic/reperfusion (I/R) on renal transporter functions, and identify the mechanisms involved in the impairment of these transporters. Myocardial ischemia and I/R were induced in rats by either 30‐minute left anterior descending coronary artery occlusion or 30‐minute occlusion followed by 120‐minute of reperfusion, respectively. The renal hemodynamic parameters and renal transporter functions were subsequently determined along with renal biochemical markers. Results showed that myocardial ischemia led to reduction in renal blood flow, perfusion pressure, and kidney function by approximately 40%, while the reperfusion phase partially recovered renal hemodynamic parameters. Moreover, myocardial ischemia and I/R progressively induced renal oxidative stresses and mitochondria dysfunction, all of which directly deteriorated renal Oat1 and Oat3 functions. Thus, this study indicates that myocardial ischemia and I/R conditions leads to a progressively declined renal transport function, which could potentially worsen AKI. Renal Oat1 and Oat3 transporters, therefore, might be potential therapeutic targets for reversing such injury.Support or Funding InformationThis research was supported by the Thailand Research Fund (RSA5980009 to CS), Faculty of Medicine Endowment Fund, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Anti-arrhythmogenic and anti-inflammatory effects of troxerutin in ischemia/reperfusion injury of diabetic myocardium

IntroductionMedicinal plants are increasingly used in the treatment of cardiovascular diseases due to their multifaceted properties. This study was designed to investigate anti-arrhythmic and anti-inflammatory potentials of the natural bioflavonoid, troxerutin (TXR) in myocardial ischemia/reperfusion (I/R) injury in diabetic rats. MethodsMale Wistar rats were randomly divided into 4 groups (control, control + TXR [150 mg/kg, daily], diabetic, and diabetic + TXR). Type-1 diabetes was induced by an intraperitoneal injection of streptozotocin (50 mg/kg) and lasted for 10 weeks. After mounting on the Langendorff apparatus, isolated hearts in all groups received a normal Krebs–Henseleit solution for 20 min of stabilization period, followed by 30 min of regional ischemia through ligation of the left anterior descending coronary artery, and 60 min of full reperfusion. During the experiment, the electrocardiograms were recorded and the arrhythmias [number, duration and incidence of premature ventricular complexes (PVC), ventricular tachycardia (VT), ventricular fibrillation (VF), and arrhythmia score] during I/R phases were assessed based on the Lambeth Convention. Ischemic left ventricular samples were used to determine the activities of lactate dehydrogenase (LDH), interleukin-1beta (IL-1β), and tumor necrosis factor (TNF-α). ResultsThe arrhythmias induced by I/R were not significantly changed in diabetic group as compared to the control group. However, pretreatment with TXR significantly reduced the number of PVC and duration and incidence of VF in ischemic phase in comparison to the untreated animals (P < 0.05). In addition, the duration, and incidence of most arrhythmias during reperfusion phase were significantly declined by TXR administration in both control and diabetic groups (P < 0.05). Pretreatment of rats with TXR significantly reduced myocardial inflammatory cytokines TNF-α and IL-1β levels after I/R insult in diabetic as well as control hearts (P < 0.05). ConclusionPreconditioning with TXR could provide cardioprotection by anti-arrhythmic and anti-inflammatory effects against I/R injury in rat hearts. This effect of TXR can introduce this material as a protective agent in cardiovascular diseases.

Application of Perfusate With Human-Derived Oxygen Carrier Solution Under Subnormothermic Machine Perfusion for Donation After Cardiac Death Liver Grafts in Pigs

Oxygenation is necessary for aerobic metabolism, which maintains adenosine triphosphate within the graft organ. In recent years, some studies have demonstrated that subnormothermic machine perfusion (SNMP) with hemoglobin-based oxygen carriers has the potential to improve oxygen metabolism. ObjectiveThe aim of this study was to evaluate the effectiveness of perfusate with human-derived hemoglobin vesicles (HbV) under SNMP in a pig model of donation after cardiac death. Materials and MethodsIn this study, pig livers were procured with a warm ischemic time of 60 minutes and were preserved in 3 groups for 240 minutes. The preservation conditions were as follows: 4°C cold storage (Group 1); SNMP with University of Wisconsin perfusate alone (Group 2); and SNMP (21°C) with University of Wisconsin solution and HbV (hemoglobin, 0.6 mg/dL) perfusate (Group 3). All livers were perfused for 120 minutes using pig autologous blood machine perfusion (reperfusion phase). We investigated the aspartate transaminase level and hemodynamics (portal vein resistance and oxygen consumption) in the preservation and reperfusion phases. A histologic study (hematoxylin-eosin staining) was performed after 240 minutes of preservation. ResultsThe portal vein resistance of Group 3 was not increased in comparison with Group 2. During preservation, the oxygen consumption of Group 3 was higher than that of Group 2. However, the level of aspartate transaminase did not differ between Groups 2 and 3. ConclusionThe present study revealed that perfusate with HbV increased the oxygen consumption of the donor liver during SNMP.

Does p53 Inhibition Suppress Myocardial Ischemia-Reperfusion Injury?

p53 is well known as a regulator of apoptosis and autophagy. In addition, a recent study showed that p53 is a modulator of the opening of the mitochondrial permeability transition pore (mPTP), a trigger event of necrosis, but the role of p53 in necrosis induced by myocardial ischemia-reperfusion (I/R) remains unclear. The aim of this study was to determine the role of p53 in acute myocardial I/R injury in perfused mouse hearts. In male C57BL6 mice between 12 and 15 weeks of age, 2 types of p53 inhibitors were used to suppress p53 function during I/R: pifithrin-α, an inhibitor of transcriptional functions of p53, and pifithrin-μ, an inhibitor of p53 translocation from the cytosol to mitochondria. Neither infusion of these inhibitors before ischemia nor infusion for the first 30-minute period of reperfusion reduced infarct size after 20-minute ischemia/120-minute reperfusion. Infarct sizes were similar in p53 heterozygous knockout mice (p53+/-) and wild-type mice (WT), but recovery of rate pressure product (RRP) 120 minutes after reperfusion was higher in p53+/- than in WT. The protein expression of p53 in WT was negligible under baseline conditions, during ischemia, and at 10 minutes after the start of reperfusion, but it became detectable at 120 minutes after reperfusion. In conclusion, upregulation of p53 during the late phase of reperfusion plays a significant role in contractile dysfunction after reperfusion, although p53 is not involved in cardiomyocyte necrosis during ischemia or in the early phase of reperfusion.

Monitoring blood-flow in the mouse cochlea using an endoscopic laser speckle contrast imaging system.

Laser speckle contrast imaging (LSCI) enables continuous high-resolution assessment of microcirculation in real-time. We applied an endoscope to LSCI to measure cochlear blood-flow in an ischemia–reperfusion mouse model. We also explored whether using xenon light in combination with LSCI facilitates visualization of anatomical position. Based on a previous preliminary study, the appropriate wavelength for penetrating the thin bony cochlea was 830 nm. A 2.7-mm-diameter endoscope was used, as appropriate for the size of the mouse cochlea. Our endoscopic LSCI system was used to illuminate the right cochlea after dissection of the mouse. We observed changes in the speckle signals when we applied the endoscopic LSCI system to the ischemia-reperfusion mouse model. The anatomical structure of the mouse cochlea and surrounding structures were clearly visible using the xenon light. The speckle signal of the cochlea was scattered, with an intensity that varied between that of the stapes (with the lowest signal), the negative control, and the stapedial artery (with the highest signal), the positive control. In the cochlear ischemia–reperfusion mouse model, the speckle signal of the cochlea decreased during the ischemic phase, and increased during the reperfusion phase, clearly reflecting cochlear blood-flow. The endoscopic LSCI system generates high-resolution images in real-time, allowing visualization of blood-flow and its changes in the mouse cochlea. Anatomical structures were clearly matched using LSCI along with visible light.

Evaluating the impact of diabetes and diabetic cardiomyopathy rat heart on the outcome of ischemia-reperfusion associated oxidative stress

Earlier literature underlines that oxidative stress plays a major role in the pathology of myocardial ischemia-reperfusion (I/R) injury, diabetic cardiomyopathy (DCM), diabetes mellitus (DM), fibrosis and hypertrophy which could adversely affect the normal cardiac function. However, the contributory role of oxidative stress in I/R pathology of heart with pre-existing abnormalities or diseases like DM and DCM remains to be explored. I/R injury was induced in normal (normal diet), DM (normal diet + streptozotocin: multiple low dose of 30 mg/kg) and DCM (high fat diet (40% fat) + streptozotocin: multiple low dose of 30 mg/kg) rat hearts using Langendorff isolated heart perfusion apparatus. Cardiac physiological recovery after I/R was assessed by hemodynamic parameters like LVDP, and LVSP, whereas cardiac injury was measured by tissue infarct size, and apoptosis, LDH, and CK release in coronary effluent. The oxidative stress was evaluated in myocardial homogenate, mitochondrial subpopulation, and microsomes. Reperfusing the ischemic DCM heart significantly deteriorated cardiac physiological recovery and elevated the cardiac injury (infarct size: 60%), compared to the control. But in DM heart, physiological recovery was prominent in the initial phase of reperfusion but deteriorated towards the end of reperfusion, supported by less infarct size. In addition, elevated lipid peroxidation (70% in DCM-I/R vs Sham) and impaired antioxidant enzymes (% decline vs Sham: GSH - 56% (DM), 63% (DCM); Catalase - 58% (DM), 35% (DCM); GPx - 19% (DM), 27% (DCM) and GR - 28% (DCM)) was observed in myocardial tissue from both DM and DCM. Interestingly, upon reperfusion, only normal heart showed significant deterioration in the antioxidant defense system. Collectively these results demonstrated that I/R induced oxidative stress is minimal in DM and DCM rat heart, despite high infarct size and low cardiac performance. This may be due to the prior adaptive modification in the antioxidant system associated with disease pathology.

Ethyl pyruvate ameliorates hepatic injury following blunt chest trauma and hemorrhagic shock by reducing local inflammation, NF-kappaB activation and HMGB1 release.

BackgroundThe treatment of patients with multiple trauma including blunt chest/thoracic trauma (TxT) and hemorrhagic shock (H) is still challenging. Numerous studies show detrimental consequences of TxT and HS resulting in strong inflammatory changes, organ injury and mortality. Additionally, the reperfusion (R) phase plays a key role in triggering inflammation and worsening outcome. Ethyl pyruvate (EP), a stable lipophilic ester, has anti-inflammatory properties. Here, the influence of EP on the inflammatory reaction and liver injury in a double hit model of TxT and H/R in rats was explored.MethodsFemale Lewis rats were subjected to TxT followed by hemorrhage/H (60 min, 35±3 mm Hg) and resuscitation/R (TxT+H/R). Reperfusion was performed by either Ringer`s lactated solution (RL) alone or RL supplemented with EP (50 mg/kg). Sham animals underwent all surgical procedures without TxT+H/R. After 2h, blood and liver tissue were collected for analyses, and survival was assessed after 24h.ResultsResuscitation with EP significantly improved haemoglobin levels and base excess recovery compared with controls after TxT+H/R, respectively (p<0.05). TxT+H/R-induced significant increase in alanine aminotransferase levels and liver injury were attenuated by EP compared with controls (p<0.05). Local inflammation as shown by increased gene expression of IL-6 and ICAM-1, enhanced ICAM-1 and HMGB1 protein expression and infiltration of the liver with neutrophils were also significantly attenuated by EP compared with controls after TxT+H/R (p<0.05). EP significantly reduced TxT+H/R-induced p65 activation in liver tissue. Survival rates improved by EP from 50% to 70% after TxT+H/R.ConclusionsThese data support the concept that the pronounced local pro-inflammatory response in the liver after blunt chest trauma and hemorrhagic shock is associated with NF-κB. In particular, the beneficial anti-inflammatory effects of ethyl pyruvate seem to be regulated by the HMGB1/NF-κB axis in the liver, thereby, restraining inflammatory responses and liver injury after double hit trauma in the rat.

Acute Limb Ischemia-Much More Than Just a Lack of Oxygen.

Acute ischemia of an extremity occurs in several stages, a lack of oxygen being the primary contributor of the event. Although underlying patho-mechanisms are similar, it is important to determine whether it is an acute or chronic event. Healthy tissue does not contain enlarged collaterals, which are formed in chronically malperfused tissue and can maintain a minimum supply despite occlusion. The underlying processes for enhanced collateral blood flow are sprouting vessels from pre-existing vessels (via angiogenesis) and a lumen extension of arterioles (via arteriogenesis). While disturbed flow patterns with associated local low shear stress upregulate angiogenesis promoting genes, elevated shear stress may trigger arteriogenesis due to increased blood volume. In case of an acute ischemia, especially during the reperfusion phase, fluid transfer occurs into the tissue while the vascular bed is simultaneously reduced and no longer reacts to vaso-relaxing factors such as nitric oxide. This process results in an exacerbative cycle, in which increased peripheral resistance leads to an additional lack of oxygen. This whole process is accompanied by an inundation of inflammatory cells, which amplify the inflammatory response by cytokine release. However, an extremity is an individual-specific composition of different tissues, so these processes may vary dramatically between patients. The image is more uniform when broken down to the single cell stage. Because each cell is dependent on energy produced from aerobic respiration, an event of acute hypoxia can be a life-threatening situation. Aerobic processes responsible for yielding adenosine triphosphate (ATP), such as the electron transport chain and oxidative phosphorylation in the mitochondria, suffer first, thus disrupting the integrity of cellular respiration. One consequence of this is irreparable damage of the cell membrane due to an imbalance of electrolytes. The eventual increase in net fluid influx associated with a decrease in intracellular pH is considered an end-stage event. Due to the lack of ATP, individual cell organelles can no longer sustain their activity, thus initiating the cascade pathways of apoptosis via the release of cytokines such as the BCL2 associated X protein (BAX). As ischemia may lead to direct necrosis, inflammatory processes are further aggravated. In the case of reperfusion, the flow of nascent oxygen will cause additional damage to the cell, further initiating apoptosis in additional surrounding cells. In particular, free oxygen radicals are formed, causing severe damage to cell membranes and desoxyribonucleic acid (DNA). However, the increased tissue stress caused by this process may be transient, as radical scavengers may attenuate the damage. Taking the above into final consideration, it is clearly elucidated that acute ischemia and subsequent reperfusion is a process that leads to acute tissue damage combined with end-organ loss of function, a condition that is difficult to counteract.

Inhibition of Peroxynitrite-Induced Mitophagy Activation Attenuates Cerebral Ischemia-Reperfusion Injury.

Activated autophagy/mitophagy has been intensively observed in ischemic brain, but its roles remain controversial. Peroxynitrite (ONOO-), as a representative of reactive nitrogen species, is considered as a critical neurotoxic factor in mediating cerebral ischemia-reperfusion (I/R) injury, but its roles in autophagy/mitophagy activation remain unclear. Herein, we hypothesized that ONOO- could induce PINK1/Parkin-mediated mitophagy activation via triggering dynamin-related protein 1 (Drp1) recruitment to damaged mitochondria, contributing to cerebral I/R injury. Firstly, we found PINK1/Parkin-mediated mitophagy activation was predominant among general autophagy, leading to rat brain injury at the reperfusion phase after cerebral ischemia. Subsequently, increased nitrotyrosine was found in the plasma of ischemic stroke patients and ischemia-reperfused rat brains, indicating the generation of ONOO- in ischemic stroke. Moreover, in vivo animal experiments illustrated that ONOO- was dramatically increased, accompanied with mitochondrial recruitment of Drp1, PINK1/Parkin-mediated mitophagy activation, and progressive infarct size in rat ischemic brains at the reperfusion phase. FeTMPyP, a peroxynitrite decomposition catalyst, remarkably reversed mitochondrial recruitment of Drp1, mitophagy activation, and brain injury. Intriguingly, further study revealed that ONOO- induced tyrosine nitration of Drp1 peptide, which might contribute to mitochondrial recruitment of Drp1 for mitophagy activation. In vitro cell experiments yielded consistent results with in vivo animal experiments. Taken together, all above findings support the hypothesis that ONOO--induced mitophagy activation aggravates cerebral I/R injury via recruiting Drp1 to damaged mitochondria.

Liver Grafts Flush and its Relation to Hemodynamic Status in Recipients of Living Donor Liver Transplantation: An Egyptian Experience

Background: There have been limited data towards the hemodynamic (HD) changes in recipients of living donor liver transplantation (LDLT) especially during the reperfusion phase. Purpose: Does surgical techniques affects the HD of the patients during reperfusion? We evaluated the differences between two surgical techniques done before the reperfusion phase of LDLT; one with liver graft flush and the other without flush. Methods: A retrospective observational study conducted at Ain Shams University Hospitals, Center of organ transplantation. Analysis of 50 recipients HD data, usage of vassopressors, ICU stay and mortality during reperfusion phase and 20 min after it, thus comparing two different methods; one with liver flush through the portal vein (PV) of 100 ml-200 ml (1.5 ml/kg-2.5 ml/kg) of blood and venting it from hepatic vein (HV), other group without liver flush technique. Results: Regarding the use of vassopressors; recipients underwent liver flush showed low initial and maintenance doses of nor-epinephrine compared to patients without flush (P ≤ 0.001), no differences detected regarding the HD state, intensive care unit (ICU) stay and blood products usage between the two techniques. Conclusion: In patients candidates for LDLT there is an increased risk of a complex and not completely understood pathology of postreperfusion syndrome (PRS), antegrade Portal vein (PV) flushing with HV venting is a surgical technique with reduced doses of vassopressors with minimal PRS hemodynamic instability.

Liver transplantation for acute liver failure due to hepatitis E in a pregnant patient.

Liver transplantation for acute liver failure due to hepatitis E in a pregnant patient.

Effect of Ischemic Postconditioning and Atorvastatin in the Prevention of Remote Lung Reperfusion Injury

ObjectiveThe aim of the present study was to evaluate the ability of ischemic postconditioning, atorvastatin and both associated to prevent or minimize reperfusion injury in the lung of rats subjected to ischemia and reperfusion by abdominal aortic clamping.MethodsWe used 41 Wistar norvegic rats, which were distributed into 5 groups: ischemia and reperfusion (I/R), ischemic postcondictioning (IPC), postconditioning + atorvastatin (IPC+A), atorvastatin (A) and SHAM. It was performed a medium laparotomy, dissection and isolation of the infra-renal abdominal aorta; except for the SHAM group, all the others were submitted to the aortic clamping for 70 minutes (ischemia) and posterior clamp removal (reperfusion, 70 minutes). In the IPC and IPC+A groups, postconditioning was performed between the ischemia and reperfusion phases by four cycles of reperfusion and ischemia lasting 30 seconds each. In the IPC+A and A groups, preceding the surgical procedure, administration of 3.4 mg/day of atorvastatin was performed for seven days by gavage. After the surgical procedure, the right caudal lobe was removed from the lung for histological study, using tissue injury score ranging from grade 1 (normal tissue) to grade 4 (intense lesion).ResultsThe mean lung injury was 3.6 in the I/R group, 1.6 in the IPC group, 1.2 in the IPC+A group, 1.2 in the A group, and 1 in the SHAM group (P<0.01).ConclusionIschemic postconditioning and atorvastatin were able to minimize lung reperfusion injury, alone or in combination.