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The noble gas argon has the potential to protect neuronal cells from cell death. So far, this effect has been studied in treatment after acute damage. Preconditioning using argon has not yet been investigated. In this study, human neuroblastoma SH-SY5Y cells were treated with different concentrations of argon (25%, 50%, and 74%; 21% O

We previously found that argon exerts its neuroprotective effect in part by inhibition of the toll-like receptors (TLR) 2 and 4. The downstream transcription factors signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa B (NF-κB) are also affected by argon and may play a role in neuroprotection. It also has been demonstrated that argon treatment could mitigate brain damage, reduce excessive microglial activation, and subsequently attenuate brain inflammation. Despite intensive research, the further exact mechanism remains unclear. In this study, human neuroblastoma cells were damaged in vitro with rotenone over a period of 4 hours (to mimic cerebral ischemia and reperfusion damage), followed by a 2-hour post-conditioning with argon (75%). In a separate in vivo experiment, retinal ischemia/reperfusion injury was induced in rats by increasing intraocular pressure for 1 hour. Upon reperfusion, argon was administered by inhalation for 2 hours. Argon reduced the binding of the transcription factors signal transducer and activator of transcription 3, nuclear factor kappa B, activator protein 1, and nuclear factor erythroid 2-related factor 2, which are involved in regulation of neuronal damage. Flow cytometry analysis showed that argon downregulated the Fas ligand. Some transcription factors were regulated by toll-like receptors; therefore, their effects could be eliminated, at least in part, by the TLR2 and TLR4 inhibitor oxidized phospholipid 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC). Argon treatment reduced microglial activation after retinal ischemia/reperfusion injury. Subsequent quantitative polymerase chain reaction analysis revealed a reduction in the pro-inflammatory cytokines interleukin (IL-1α), IL-1β, IL-6, tumor necrosis factor α, and inducible nitric oxide synthase. Our results suggest that argon reduced the extent of inflammation in retinal neurons after ischemia/reperfusion injury by suppression of transcription factors crucial for microglial activation. Argon has no known side effects or narcotic properties; therefore, therapeutic use of this noble gas appears ideal for treatment of patients with neuronal damage in retinal ischemia/reperfusion injury. The animal experiments were approved by the Commission for Animal Care of the University of Freiburg (approval No. 35-9185.81/G14-122) on October 19, 2012.

OBJECTIVES Neurologic damage following cardiac arrest remains a major burden for modern resuscitation medicine. Cardiopulmonary resuscitation with extracorporeal circulatory support holds the potential to reduce morbidity and mortality. Furthermore, the endogenous gasotransmitter carbon monoxide attracts attention in reducing cerebral injury. We hypothesize that extracorporeal resuscitation with additional carbon monoxide application reduces neurologic damage. DESIGN Randomized, controlled animal study. SETTING University research laboratory. SUBJECTS Landrace-hybrid pigs. INTERVENTIONS In a porcine model, carbon monoxide was added using a novel extracorporeal releasing system after resuscitation from cardiac arrest. MEASUREMENTS AND MAIN RESULTS As markers of cerebral function, neuromonitoring modalities (somatosensory-evoked potentials, cerebral oximetry, and transcranial Doppler ultrasound) were used. Histopathologic damage and molecular markers (caspase-3 activity and heme oxygenase-1 expression) were analyzed. Cerebral oximetry showed fast rise in regional oxygen saturation after carbon monoxide treatment at 0.5 hours compared with extracorporeal resuscitation alone (regional cerebral oxygen saturation, 73% ± 3% vs 52% ± 8%; p < 0.05). Median nerve somatosensory-evoked potentials showed improved activity upon carbon monoxide treatment, whereas post-cardiac arrest cerebral perfusion differences were diminished. Histopathologic damage scores were reduced compared with customary resuscitation strategies (hippocampus: sham, 0.4 ± 0.2; cardiopulmonary resuscitation, 1.7 ± 0.4; extracorporeal cardiopulmonary resuscitation, 2.3 ± 0.2; extracorporeal cardiopulmonary resuscitation with carbon monoxide application [CO-E-CPR], 0.9 ± 0.3; p < 0.05). Furthermore, ionized calcium-binding adaptor molecule 1 staining revealed reduced damage patterns upon carbon monoxide treatment. Caspase-3 activity (cardiopulmonary resuscitation, 426 ± 169 pg/mL; extracorporeal cardiopulmonary resuscitation, 240 ± 61 pg/mL; CO-E-CPR, 89 ± 26 pg/mL; p < 0.05) and heme oxygenase-1 (sham, 1 ± 0.1; cardiopulmonary resuscitation, 2.5 ± 0.4; extracorporeal cardiopulmonary resuscitation, 2.4 ± 0.2; CO-E-CPR, 1.4 ± 0.2; p < 0.05) expression were reduced after carbon monoxide exposure. CONCLUSIONS Carbon monoxide application during extracorporeal resuscitation reduces injury patterns in neuromonitoring and decreases histopathologic cerebral damage by reducing apoptosis. This may lay the basis for further clinical translation of this highly salutary substance.

Neuronal ischemia-reperfusion injury (IRI), such as it can occur in glaucoma or strokes, is associated with neuronal cell death and irreversible loss of function of the affected tissue. Hydrogen sulfide (HIschemia-reperfusion injury was induced in rats by a temporary increase in intraocular pressure (1 h). HBoth inhalative and intravenously delivered HHydrogen sulfide acts, at least in part, via the mitogen-activated protein kinase (MAPK) ERK1/2 to reduce apoptosis and inflammation. Both inhalative H

Background: The ischemia-reperfusion injury (IRI) of neuronal tissue, such as the brain and retina, leads to possible cell death and loss of function. Current treatment options are limited, but preliminary observations suggest a protective effect of hydrogen sulfide (H2S). However, the dosage, timing, and mechanism of inhaled H2S treatment after IRI requires further exploration. Methods: We investigated possible neuroprotective effects of inhaled H2S by inducing retinal ischemia–reperfusion injury in rats for the duration of 1 h (120 mmHg), followed by the administration of hydrogen sulfide (H2S) for 1 h at different time points (0, 1.5, and 3 h after the initiation of reperfusion) and at different H2S concentrations (120, 80, and 40 ppm). We quantified the H2S effect by conducting retinal ganglion cell counts in fluorogold-labeled animals 7 days after IRI. The retinal tissue was harvested after 24 h for molecular analysis, including qPCR and Western blotting. Apoptotic and inflammatory mediators, transcription factors, and markers for oxidative stress were investigated. Histological analyses of the retina and the detection of inflammatory cytokines in serum assays were also performed. Results: The effects of inhaled H2S were most evident at a concentration of 80 ppm administered 1.5 h after IRI. H2S treatment increased the expression of anti-apoptotic Bcl-2, decreased pro-apoptotic Bax expression, reduced the release of the inflammatory cytokines IL-1β and TNF-α, attenuated NF-κB p65, and enhanced Akt phosphorylation. H2S also downregulated NOX4 and cystathionine β-synthase. Histological analyses illustrated a reduction in TNF-α in retinal ganglion cells and lower serum levels of TNF-α in H2S-treated animals after IRI. Conclusion: After neuronal IRI, H2S mediates neuroprotection in a time- and dose-dependent manner. The H2S treatment modulated transcription factor NF-κB activation and reduced retinal inflammation.

Deleterious consequences like acute kidney injury frequently occur upon successful resuscitation from cardiac arrest. Extracorporeal life support is increasingly used to overcome high cardiac arrest mortality. Carbon monoxide (CO) is an endogenous gasotransmitter, capable of reducing renal injury. In our study, we hypothesized that addition of CO to extracorporeal resuscitation hampers severity of renal injury in a porcine model of cardiac arrest. Hypoxic cardiac arrest was induced in pigs. Animals were resuscitated using a conventional [cardiopulmonary resuscitation (CPR)], an extracorporeal (E-CPR), or a CO-assisted extracorporeal (CO-E-CPR) protocol. CO was applied using a membrane-controlled releasing system. Markers of renal injury were measured, and histopathological analyses were carried out. We investigated renal pathways involving inflammation as well as apoptotic cell death. No differences in serum neutrophil gelatinase-associated lipocalin (NGAL) were detected after CO treatment compared with Sham animals (Sham 71 ± 7 and CO-E-CPR 95 ± 6 ng/mL), while NGAL was increased in CPR and E-CPR groups (CPR 135 ± 11 and E-CPR 124 ± 5 ng/mL; P < 0.05). Evidence for histopathological damage was abrogated after CO application. CO increased renal heat shock protein 70 expression and reduced inducible cyclooxygenase 2 (CPR: 60 ± 8; E-CPR 56 ± 8; CO-E-CPR 31 ± 3 µg/mL; P < 0.05). Caspase 3 activity was decreased (CPR 1,469 ± 276; E-CPR 1,670 ± 225; CO-E-CPR 755 ± 83 pg/mL; P < 0.05). Furthermore, we found a reduction in renal inflammatory signaling upon CO treatment. Our data demonstrate improved renal function by extracorporeal CO treatment in a porcine model of cardiac arrest. CO reduced proinflammatory and proapoptotic signaling, characterizing beneficial aspects of a novel treatment option to overcome high mortality.

Purpose: Delayed graft function is a major complication after kidney transplantation affecting patients’ long-term outcome. The aim of this study was to identify modifiable risk factors for delayed graft function after deceased donor kidney transplantation. Methods: This is a single-center retrospective cohort study of a university transplantation center. Univariate and multivariate step-wise logistic regression analysis of patient-specific and procedural risk factors were conducted. Results: We analyzed 380 deceased donor kidney transplantation patients between October 30, 2008 and December 30, 2017. The incidence of delayed graft function was 15% (58/380). Among the patient-specific risk factors recipient diabetes (2.8 [1.4-5.9] odds ratio [OR] [95% confidence interval [CI]]), American Society of Anesthesiologist score of 4 (2.7 [1.2-6.5] OR [95% CI]), cold ischemic time >13 hours (2.8 [1.5-5.3] OR [95% CI]) and donor age >55 years (1.9 [1.01-3.6] OR [95% CI]) revealed significance. The significant intraoperative, procedural risk factors included the use of colloids (3.9 [1.4-11.3] OR [95% CI]), albumin (3.0 [1.2-7.5] OR [95% CI]), crystalloids >3000 mL (3.1 [1.2-7.5] OR [95% CI]) and mean arterial pressure Conclusion: Patients undergoing deceased donor kidney transplantation with a mean arterial pressure >80 mm Hg at the time of transplant reperfusion without requiring excessive fluid therapy in terms of colloids, albumin or crystalloids >3000 mL are less likely to develop delayed graft function.

Aims Heart disease of different aetiology remains the leading cause of cardiac arrest (CA). Despite efforts to improve the quality of cardiopulmonary resuscitation (CPR), subsequent myocardial and systemic damage after CA still present a major long-term burden. Low-dose carbon monoxide (CO) is known to exert protective effects in cardiovascular pathophysiology but clinical applications are challenged by unfavourable delivery modes. We tested the hypothesis that extracorporeal resuscitation (E-CPR) in combination with controlled fast onset CO delivery results in improved cardiac physiology and haemodynamics. Damage-associated molecular pattern (DAMP) signalling may be part of the molecular mechanism. Methods and results In an established porcine model, E-CPR was performed. While E-CPR leads to similar results as compared to a conventional CPR strategy, CO delivery in combination with E-CPR demonstrated significant cardioprotection. Cardiac performance analysis using echocardiography and thermodilution techniques showed a CO-dependent improved cardiac function compared to severe myocardial dysfunction in CPR and E-CPR (left ventricular ejection fraction: Sham 49 ± 5; CPR 26 ± 2; E-CPR 25 ± 2; CO-E-CPR 31 ± 4; P Conclusions CO treatment restores myocardial function and improves systemic macro- and microhaemodynamics in E-CPR through a reduction in DAMPs.

PLOS ONE 17(1), e0262110 (2022). doi:10.1371/journal.pone.0262110, Published by PLOS, San Francisco, California, US

BACKGROUND The success of ventilation with a laryngeal mask depends crucially on the seal between the mask and the periglottic tissue. Increasing the laryngeal mask's cuff volume is known to reduce oral air leakage but may lead to gastric insufflation. OBJECTIVE We hypothesised that a lower cuff pressure would result in less gastric insufflation. We sought to compare gastric insufflation with laryngeal mask cuff pressures of 20 cmH2O (CP20) and 60 cmH2O (CP60) during increasing peak airway pressures in a randomised controlled double-blind cross-over study. We also evaluated the incidence of gastric insufflation at the recommended peak airway pressure of 20 cmH2O or less and during both intermittent positive airway pressure and continuous positive airway pressure. METHODS After obtaining ethics approval and written informed consent, 184 patients ventilated via laryngeal mask received a stepwise increase in peak airway pressure from 15 to 30 cmH2O with CP20 and CP60 in turn. Gastric insufflation was determined via real-time ultrasound and measurement of the cross-sectional area of the gastric antrum. The primary endpoint was the incidence of gastric insufflation at the different laryngeal mask cuff pressures. RESULTS Data from 164 patients were analysed. Gastric insufflation occurred less frequently at CP20 compared with CP60 (P

A potential shortage of intensive care ventilators has led to the idea to ventilate more than one patient with a single ventilator. Besides other problems, this is associated with the lack of knowledge concerning distribution of tidal volume and the patients’ individual respiratory system mechanics.In this study we used two simple hand-manufactured adaptors to connect physical models of two adult respiratory systems to one ventilator. The artificial lungs were ventilated in the pressure-controlled mode and we investigated if disconnecting one lung from the ventilation circuit for several breaths would allow to determine reliably the other lung’s tidal volume and compliance.Compliances and volumes were measured both with the ventilator and external sensors corresponded well. However, tidal volumes measured via the ventilator were smaller compared to the tidal volumes measured via the external sensors with an absolute error of 5.3 ± 2.5%. The tidal volumes of the individual artificial lungs were distributed in proportion to the compliances and did not differ relevantly when both artificial lungs were connected to when one was disconnected.We conclude that in case of emergency, ventilation of two patients with one ventilator requires two simple hand-crafted tubes as adaptors and available standard breathing circuit components. In such a setting, respiratory system mechanics and tidal volume of each individual patient can be reliably measured during short term clamping of the tracheal tube of the respective other patient.

Background The anaesthesia ventilator represents the key equipment for intraoperative respiratory care. Improper operation of this device may threaten a patient's health. A self-explanatory interface facilitates handling and decreases the risk of operating errors. This study systematically evaluates the usability of user interfaces in four modern anaesthesia ventilators. Methods Twenty naive operators were asked to execute 20 tasks on each of four different anaesthesia ventilators (Avance CS2™, GE Healthcare; Flow-i™, Maquet; and Perseus™ and Primus™, Drager) in a randomized order. The success of task execution, frequency of requests for assistance, and processing times were recorded. During the tasks, the operators' visual focus was measured via eye-tracking. Additionally, subjective assessments of usability were evaluated by a standardized questionnaire. For comparison, six experienced operators undertook the same protocol. Results The overall rate of falsely executed tasks was low. Naive operators requested assistance least when using the Perseus (26). Pooled processing times were shortest for the Perseus (222 s), followed by the Primus (223 s), the Avance (238 s), and the Flow-i (353 s). Task-specific processing times differed considerably between the devices. Eye-tracking analyses revealed associated interface issues that impeded the operators' performance. Operators rated usability best for the Perseus [mean ( sd ): 67 (17) arbitrary units] and worst for the Flow-i [50 (16) arbitrary units]. Results from experienced operators support these findings by trend. Conclusions The usability of modern anaesthesia ventilators differs considerably. Interface issues of specific tasks impair the operator's efficiency. Eliminating the specific usability issues might improve the operator's performance and, as a consequence, the patient's safety.

Background: Perioperative damage of neuronal tissue due to insufficient cerebral circulation as a result of hypotension or stroke, lead to permanent destruction and functional impairment via apoptotic and inflammatory pathways. Recently, the noble gas argon has been shown to exert neuroprotective effects. Despite intensive research, the exact mechanism remains unclear. Methods: In-vitro, after injury of human neuroblastoma cells with rotenone over a period of four hours, postconditioning with argon 75 Vol% was performed for 2. In-vivo, retinal ischemia reperfusion injury in the rat was induced by increasing intraocular pressure for 1 hour (h). Upon reperfusion, argon was administered by inhalation for 2 h. Results: In summary, argon reduced binding activity of transcription factors involved in regulation of neuronal damage such as STAT3 (Signal transducer and activator of transcription 3), NF-kB (Nuclear factor `kappa-light-chain-enhancer´ of activated B-cells), AP-1 (Activator protein 1) and Nrf-2 (Nuclear factor erythroid 2-related factor 2). Flow cytometry analysis showed that argon down-regulated the Fas-Ligand. Since some of these transcription factors were regulated via toll-like receptors (TLR), their effects could be eliminated - at least in part - by OxPAPC (TLR2 and -4 inhibitor). Argon was able to reduce the quantity and the activity of neuronal microglia after ischemia-reperfusion injury. Consecutively, qPCR (quantitative Polymerase chain reaction) showed a reduction of the pro-inflammatory cytokines IL-1α (Interleukin-1α), IL-1ß (Interleukin-1ß), IL-6 (Interleukin 6), TNFα (Tumor necrosis factor alpha) and iNOS (inducible Nitric oxide synthase). Conclusion: Argon reduced the extent of inflammation after neuronal injury by suppression of transcription factors crucial for microglia activation. The therapeutic use of the noble gas would be ideal for treating in the context of neuronal damage due to the lack of known side effects and narcotic properties with preservation of neurological assessability. Although preclinical studies are promising, further investigations are required before argon can be approved for use in patients.

Argon has recently come into scientific focus as a neuroprotective agent. The underlying neuroprotective mechanism remains unknown although toll-like receptors were recently suggested to play an important role. We hypothesized that TLR-associated downstream transcription factors are responsible for argon's effects, leading to anti-apoptotic and anti-inflammatory properties. Apoptosis was induced in human neuroblastoma cells. Immediately afterwards, argon treatment (75 Vol% for 2 h) was initiated. Cells were analyzed, measuring mitochondrial membrane potential, reactive-oxygen-species, annexin-V/propidium iodide staining, transcription factor phosphorylation and binding activity as well as protein and mRNA expression of interleukins. Argon's in vivo effects were analyzed by quantification of retinal ganglion cell density, mRNA expression, serum cytokine analysis and immunohistochemistry after retinal ischemia reperfusion injury (IRI) in rats. Argon diminished rotenone-induced kappa-light-chain-enhancer' of activated B-cells (NF-κB) and signal transducer and activator of transcription 3 (STAT3) but not STAT5 or cAMP-response element-binding protein (CREB) phosphorylation and DNA-binding activity. Argon treatment attenuated apoptosis by preservation of mitochondrial membrane potential and decline in reactive oxygen species (ROS) generation. NF-κB and STAT3 inhibition, as well as TLR2 and TLR4 inhibition reversed argon's effects on IL-8 mRNA expression. Argon attenuated rotenone-induced IL-8 protein and mRNA expression in vitro. Inhibition of TLR2 and 4 attenuated argon's protective effect in vivo reducing IRI driven retinal IL-8 expression. IL-8 expression was found in the retina in co-localization with Müller cells and retinal ganglion cells. Argon mediates its neuroprotective effects by TLR-mediated regulation of transcription factors NF-κB and STAT3, thus decreasing interleukin-8 expression in vitro and in vivo. These findings may open up new opportunities to effectively treat cerebral ischemia and reperfusion injury through the inhalation of argon. Argon exerts its protective effects in vitro and in vivo via toll-like receptors TLR2 and TLR4 signaling, followed by alteration of downstream enzymes. In conclusion, argon mediates its beneficial effects by suppression of STAT3 and NF-κB phosphorylation and subsequent suppression of interleukin IL-8 protein expression. These novel findings may open up opportunities for argon as a therapeutic agent, particularly in the treatment of neuronal injury. Cover image for this issue: doi: 10.1111/jnc.13334.

Extracorporeal circulation can be accompanied by increased vascular permeability leading to pathological fluid balance and organ dysfunction. The second messenger cAMP is involved in capillary permeability and maintains endothelial integrity. The aim of the present study was to evaluate the effect of phosphodiesterase-4 (PDE4) inhibition with rolipram on extracorporeal circulation-induced capillary leakage, microcirculatory dysfunction, and organ injury in rodents. Rats were randomly allocated to the following groups: sham ( n = 5), venoarterial extracorporeal circulation [extracorporeal life support (ECLS), n = 7], ECLS + rolipram ( n = 7), extracorporeal resuscitation (ECPR; n = 7), and ECPR + rolipram ( n = 7). In the groups that underwent ECPR, ECLS-based cardiopulmonary resuscitation (ECPR) was performed after the induction of hypoxic cardiac arrest. Upon return of spontaneous circulation, rolipram was administered intravenously. The mesenteric microcirculation was studied using intravital microscopy, and organ specimens were harvested upon completion of the study. ECLS and ECPR induced a proinflammatory response (cytokines IL-1β, IL-6, and TNF-α). Although PDE4 expression was upregulated in vascular tissue, PDE4 inhibition abrogated impaired microcirculation and capillary leak (albumin extravasation of the sham group: 1 ± 0.03-fold, ECLS group: 1.2 ± 0.05-fold, ECLS + rolipram group: 0.99 ± 0.04-fold, ECPR group: 1.6 ± 0.04-fold, and ECPR + rolipram group: 1.06 ± 0.02-fold from the sham group, P < 0.05). PDE4 inhibition led to stabilization of vascular cAMP levels but did not affect cytokine levels. Capillary leak was reduced, as demonstrated by the decrease of the systemic biomarkers soluble vascular-endothelial cadherin and activated complement 3. Histological analysis revealed reduced injury to the lungs and kidneys after PDE4 inhibition, with a significant decrease in systemic renal damage markers. Our findings demonstrate that extracorporeal circulation causes an inflammatory reaction associated with decreased vascular cAMP levels, increased vascular permeability, and impaired microcirculation. PDE4 inhibition proved to be capable of reducing these side effects in ECLS and ECPR, leading to reduced microcirculatory, renal, and pulmonary injury. NEW & NOTEWORTHY Various complications are common after extracorporeal circulation. Among these, endothelial injury may cause impaired microcirculation and capillary leak. Here, we report that phosphodiesterase-4 inhibition targeting endothelial cAMP is capable of reducing microvascular complications in a rodent model of extracorporeal resuscitation. Microcirculation and vascular permeability are influenced without targeting extracorporeal circulation-induced inflammation. Thus, pulmonary and renal organ protection may be conferred.

Background: The beneficial effects of epidural analgesia (EDA) in terms of pain control and postoperative convalescence are widely known and led to a frequent use for patients who underwent living donor kidney nephrectomy. The objective of this study was to determine whether general anesthesia (GA) plus EDA compared to GA only, administered for living donor nephrectomy has effects on postoperative graft function in recipients. Methods: In this monocentric, retrospective cohort analysis we analyzed the closed files of all consecutive donor- recipient pairs who underwent living donor kidney transplantations from 2008 to 2017. The outcome variable was delayed graft function (DGF), defined as at least one hemodialysis within seven days postoperatively, once hyperacute rejection, vascular or urinary tract complications were ruled out. Statistical analyses of continuous variables were calculated using the two-tail Student’s t test and Fisher exact test for categorical variables with a significance level of pResults: The study enclosed 291 consecutive living donor kidney transplantations. 99 kidney donors received epidural analgesia whereas 192 denied epidural analgesia. The groups showed balanced pretransplantational characteristics and comparable donors´ and recipients’ risk factors. 9 out of all 291 recipients needed renal replacement therapy (RRT) during the first 7 days due to delayed graft function; all of these donors received no EDA. The observed rate of DGF in recipients whose kidney donors received epidural analgesia was significantly lower (0% vs. 4.6%; pConclusions: In our cohort we observed a significantly lower rate of DGF when epidural analgesia for donor nephrectomy was administered. Du to restrictions of the study design this observation needs further confirmation by prospective studies. Key words: Kidney transplantation, delayed graft function, epidural analgesia, donor nephrectomy

In contrast to conventional mandatory ventilation, a new ventilation mode, expiratory ventilation assistance (EVA), linearises the expiratory tracheal pressure decline.We hypothesised that due to a recruiting effect, linearised expiration oxygenates better than volume controlled ventilation (VCV). We compared the EVA with VCV mode with regard to gas exchange, ventilation volumes and pressures and lung aeration in a model of peri-operative mandatory ventilation in healthy pigs.Controlled interventional trial.Animal operating facility at a university medical centre.A total of 16 German Landrace hybrid pigs.The lungs of anaesthetised pigs were ventilated with the EVA mode (n=9) or VCV (control, n=7) for 5 h with positive end-expiratory pressure of 5 cmH2O and tidal volume of 8 ml kg. The respiratory rate was adjusted for a target end-tidal CO2 of 4.7 to 6 kPa.Tracheal pressure, minute volume and arterial blood gases were recorded repeatedly. Computed thoracic tomography was performed to quantify the percentages of normally and poorly aerated lung tissue.Two animals in the EVA group were excluded due to unstable ventilation (n=1) or unstable FiO2 delivery (n=1). Mean tracheal pressure and PaO2 were higher in the EVA group compared with control (mean tracheal pressure: 11.6 ± 0.4 versus 9.0 ± 0.3 cmH2O, P 0.001 and PaO2: 19.2 ± 0.7 versus 17.5 ± 0.4 kPa, P = 0.002) with comparable peak inspiratory tracheal pressure (18.3 ± 0.9 versus 18.0 ± 1.2 cmH2O, P 0.99). Minute volume was lower in the EVA group compared with control (5.5 ± 0.2 versus 7.0 ± 1.0 l min, P = 0.02) with normoventilation in both groups (PaCO2 5.4 ± 0.3 versus 5.5 ± 0.3 kPa, P 0.99). In the EVA group, the percentage of normally aerated lung tissue was higher (81.0 ± 3.6 versus 75.8 ± 3.0%, P = 0.017) and of poorly aerated lung tissue lower (9.5 ± 3.3 versus 15.7 ± 3.5%, P = 0.002) compared with control.EVA ventilation improves lung aeration via elevated mean tracheal pressure and consequently improves arterial oxygenation at unaltered positive end-expiratory pressure (PEEP) and peak inspiratory pressure (PIP). These findings suggest the EVA mode is a new approach for protective lung ventilation.

Carbon monoxide (CO) has demonstrated therapeutic potential in multiple inflammatory conditions including intensive care applications such as organ transplantation or sepsis. Approaches to translate these findings into future therapies, however, have been challenged by multiple hurdles including handling and toxicity issues associated with systemic CO delivery. Here, we describe a membrane-controlled Extracorporeal Carbon Monoxide Release System (ECCORS) for easy implementation into Extracorporeal Membrane Oxygenation (ECMO) setups, which are being used to treat cardiac and respiratory diseases in various intensive care applications. Functionalities of the ECCORS were investigated in a pig model of veno-arterial ECMO. By precisely controlling CO generation and delivery as a function of systemic carboxyhemoglobin levels, the system allows for an immediate onset of therapeutic CO-levels while preventing CO-toxicity. Systemic carboxyhemoglobin levels were profiled in real-time by monitoring exhaled CO levels as well as by pulse oximetry, enabling self-contained and automatic feedback control of CO generation within ECCORS. Machine learning based mathematical modeling was performed to increase the predictive power of this approach, laying foundation for high precision systemic CO delivery concepts of tomorrow.

Oxygen therapy is a life-sustaining treatment for patients with respiratory failure. However, prolonged exposure to high oxygen concentrations often results in hyperoxia-induced acute lung injury (HALI). At present, no effective therapeutic intervention can attenuate the development of HALI. In the present study, we investigated whether hydrogen sulfide (H2S) can confer lung protection in a mouse model of HALI. C57BL/6 mice were either exposed to room air or 90 vol% oxygen and received either the H2S donor sodium hydrosulfide (NaHS, 10 mg/kg) or vehicle. Lung injury was assessed by an HALI score in tissue sections. Bronchoalveolar lavage fluid was analyzed for protein content and cellular infiltration. Reactive oxygen species (ROS) were detected by dihydroethidium staining. Angiopoietin- 2 was detected by Western Blotting. Pulmonary epithelial, endothelial, and macrophage cells were stimulated to produce ROS either in the absence or presence of NaHS. Mice exposed to hyperoxia developed substantial lung injury, characterized by an elevated HALI score, cellular infiltration, protein leakage, ROS production, and overexpression of angiopoietin-2. NaHS treatment abolished morphological indices of HALI. Angiopoietin-2 expression was significantly reduced by NaHS in vivo. In endothelial cells and macrophages, angiopoietin-2 was released due to ROS formation and decreased in the presence of NaHS. In conclusion, H2S protects from HALI by preventing ROS production and angiopoietin-2 release.

BACKGROUND: Mechanical ventilation is an important perioperative tool in anesthesia and a lifesaving treatment for respiratory failure, but it can lead to ventilator-associated lung injury. Inhaled anesthetics have demonstrated protective properties in various models of organ damage. We compared the lung-protective potential of inhaled sevoflurane, isoflurane, and desflurane in a mouse model of ventilator-induced lung injury (VILI). METHODS: C57BL/6N mice were randomized into 5 groups (n = 8/group). One group served as a control and 4 groups were subjected to mechanical ventilation with air (12 mL/kg tidal volume) for 6 hours. Ventilated animals were anesthetized with either ketamine and acepromazine, or 1 of 3 inhaled anesthetics: isoflurane, sevoflurane, or desflurane. Lung injury was assessed by lung histology, neutrophil counts, and interleukin-1β concentrations in bronchoalveolar lavage fluid. Antioxidant effects were explored by evaluation of production of reactive oxygen species (ROS) and glutathione content in lung tissue by immunofluorescence staining and confocal laser scanning microscopy. Changes in intercellular adhesion molecule-1 and src-protein-tyrosine-kinase levels were determined by real-time polymerase chain reaction and Western blot. RESULTS: Compared with nonventilated controls, ventilated mice anesthetized with ketamine had thickened alveolar walls, elevated VILI scores, higher polymorph neutrophil counts, and increased ROS production. Mice anesthetized with isoflurane and sevoflurane showed thinner alveolar septa, lower VILI scores, lower polymorph neutrophil counts, and lower interleukin-1β concentrations than ketamine mice. The expression of intercellular adhesion molecule-1/src-protein-tyrosine-kinase was neither affected by mechanical ventilation nor affected by administration of inhaled anesthetics. Mice anesthetized with isoflurane and sevoflurane showed less ROS production and higher glutathione contents compared with ketamine mice. Unexpectedly, desflurane-ventilated mice showed similar signs of lung injury compared with mice ventilated with air alone and receiving ketamine anesthesia. Desflurane failed to inhibit inflammatory responses and ROS production in lung tissue and developed no antioxidant potential. CONCLUSIONS: Although isoflurane and sevoflurane prevent ventilator-associated lung injury, desflurane does not. As an underlying mechanism, both inhaled anesthetics exert major anti-inflammatory and antioxidative effects.

Propofol, midazolam and ketamine are widely used in today's anaesthesia practice. Both neuroprotective and neurotoxic effects have been attributed to all three agents.To establish whether propofol, midazolam and ketamine in the same neuronal injury model exert neuroprotective effects on injured neurones in vitro and in vivo by modulation of the Toll-like receptor 4-nuclear factor kappa-light-chain-enhancer of activated B cells (TLR-4-NF-κB) pathway.Cell-based laboratory (n = 6 repetitions per experiment) and animal (n = 6 per group) studies using a neuronal cell line (SH-SY5Y cells) and adult Sprague-Dawley rats.Cells were exposed to oxygen-glucose deprivation before or after treatment using escalating, clinically relevant doses of propofol, midazolam and ketamine. In animals, retinal ischaemia (60 min) was induced followed by reperfusion and randomised treatment with saline or propofol.Neuronal cell death was determined using flow-cytometry (mitochondrial membrane potential) and lactate dehydrogenase (LDH) release. Nuclear factor NF-κB and hypoxia-inducible factor 1 α-activity were analysed by DNA-binding ELISA, expression of NF-κB-dependent genes and TLR-4 by luciferase-assay and flow-cytometry, respectively. In animals, retinal ganglion cell density, caspase-3 activation and gene expression (TLR-4, NF-κB) were used to determine in vivo effects of propofol. Results were compared using ANOVA (Analysis of Variance) and t test. A P value less than 0.05 was considered statistically significant.Post-treatment with clinically relevant concentrations of propofol (1 to 10 μg ml) preserved the mitochondrial membrane potential in oxygen-glucose deprivation-injured cells by 54% and reduced LDH release by 21%. Propofol diminished TLR-4 surface expression and preserved the DNA-binding activity of the protective hypoxia-inducible factor 1 α transcription factor. DNA-binding and transcriptional NF-κB-activity were inhibited by propofol. Neuronal protection and inhibition of TLR-4-NF-κB signalling were not consistently seen with midazolam or ketamine. In vivo, propofol treatment preserved rat retinal ganglion cell densities (cells mm, saline 1504 ± 251 vs propofol 2088 ± 144, P = 0.0001), which was accompanied by reduced neuronal caspase-3, TLR-4 and NF-κB expression.Propofol, but neither midazolam nor ketamine, provides neuroprotection to injured neuronal cells via inhibition of TLR-4-NF-κB-dependent signalling.

Mechanical ventilation causes ventilator-induced lung injury (VILI), and contributes to acute lung injury/acute respiratory distress syndrome (ALI/ARDS), a disease with high morbidity and mortality among critically ill patients. Carbon monoxide (CO) can confer lung protective effects during mechanical ventilation. This study investigates the time dependency of CO therapy with respect to lung protection in animals subjected to mechanical ventilation. For this purpose, mice were ventilated with a tidal volume of 12 ml/kg body weight for 6 h with air in the absence or presence of CO (250 parts per million). Histological analysis of lung tissue sections was used to determine alveolar wall thickening and the degree of lung damage by VILI score. Bronchoalveolar lavage fluid was analyzed for total cellular influx, neutrophil accumulation, and interleukin-1β release. As the main results, mechanical ventilation induced pulmonary edema, cytokine release, and neutrophil recruitment. In contrast, application of CO for 6 h prevented VILI. Although CO application for 3 h followed by 3-h air ventilation failed to prevent lung injury, a further reduction of CO application time to 1 h in this setting provided sufficient protection. Pre-treatment of animals with inhaled CO for 1 h before ventilation showed no beneficial effect. Delayed application of CO beginning at 3 or 5 h after initiation of ventilation, reduced lung damage, total cell influx, and neutrophil accumulation. In conclusion, administration of CO for 6 h protected against VILI. Identical protective effects were achieved by limiting the administration of CO to the first hour of ventilation. Pre-treatment with CO had no impact on VILI. In contrast, delayed application of CO led to anti-inflammatory effects with time-dependent reduction in tissue protection.

Objectives Pancreatic stellate cells (PSCs) play a crucial role during pancreatic fibrosis development. Hydrogen sulfide (H2S) is a recently discovered gaseous transmitter, whose role in PSCs has not been explored yet. In the present study, we examined the effects of sodium hydrosulfide (NaHS), an H2S donor, on rat PSCs and elucidated the mechanisms involved. Methods Primary PSCs were isolated from rat pancreatic tissue. Lactate dehydrogenase and caspase assays were performed to detect cell death. Pancreatic stellate cell proliferation was determined by cell count analyses, bromodeoxyuridine incorporation, and flow cytometry. The role of heme oxygenase-1 (HO-1) was assessed by pharmacological HO inhibition and transfection of HO-1 small interfering RNA. Pancreatic stellate cell migration was determined by a wound healing assay, and PSC contraction was assessed by a gel contraction assay. α-Smooth muscle actin, collagen type I, and fibronectin messenger RNAs were analyzed by real-time polymerase chain reaction. Results NaHS inhibited PSC proliferation at nontoxic concentrations. This was associated with HO-1–mediated repression of extracellular signal–regulated kinase 1/2 signaling. NaHS suppressed PSC migration and activation as well as extracellular matrix synthesis. Conclusions The results of the present study indicate that NaHS inhibits key cell functions of PSCs. Administration of H2S-releasing compounds might represent a novel strategy in the treatment of pancreatic fibrosis.

Retinal ischemia and reperfusion injuries (R-IRI) damage neuronal tissue permanently. Recently, we demonstrated that Argon exerts anti-apoptotic and protective properties. The molecular mechanism remains unclear. We hypothesized that Argon inhalation exert neuroprotective effects in rats retinal ganglion cells (RGC) via an ERK-1/2 dependent regulation of heat-shock proteins. Inhalation of Argon (75 Vol%) was performed after R-IRI on the rats' left eyes for 1 h immediately or with delay. Retinal tissue was harvested after 24 h to analyze mRNA and protein expression of heat-shock proteins -70, -90 and heme-oxygenase-1, mitogen-activated protein kinases (p38, JNK, ERK-1/2) and histological changes. To analyze ERK dependent effects, the ERK inhibitor PD98059 was applicated prior to Argon inhalation. RGC count was analyzed 7 days after injury. Statistics were performed using anova. Argon significantly reduced the R-IRI-affected heat-shock protein expression (p < 0.05). While Argon significantly induced ERK-1/2 expression (p < 0.001), inhibition of ERK-1/2 before Argon inhalation resulted in significantly lower vital RGCs (p < 0.01) and increase in heme-oxygenase-1 (p < 0.05). R-IRI-induced RGC loss was reduced by Argon inhalation (p < 0.001). Immunohistochemistry suggested ERK-1/2 activation in Muller cells. We conclude, that Argon treatment protects R-IRI-induced apoptotic loss of RGC via an ERK-1/2 dependent regulation of heme-oxygenase-1. We proposed the following possible mechanism for Argon-mediated neuroprotection: Argon exerts its protective effects via an induction of an ERK with subsequent suppression of the heat shock response. In conclusion, ischemia and reperfusion injuries and subsequent neuronal apoptosis are attenuated. These novel findings may open up new opportunities for Argon as a therapeutic option, especially since Argon is not toxic.

Background The authors investigated whether total intravenous anesthesia (TIVA) with precalculated equipotent infusion schemes for remifentanil and alfentanil would ensure appropriate analgesia and that remifentanil would result in better recovery characteristics. Methods Forty consenting patients (classified as American Society of Anesthesiologists physical status I-III) scheduled for microlaryngoscopy were randomized to receive, in a double-blind manner, either remifentanil (loading dose 1 microg/kg; maintenance infusion, 0.25 microg x kg(-1) x min-1) or alfentanil (loading dose, 50 microg/kg; maintenance infusion, 1 microg x kg(-1) x min-1) as the analgesic component of TIVA. They were combined with propofol (loading dose, 2 mg/kg; maintenance infusion, 100 microg x kg(-1) min(-1)). To insure an equal state of anesthesia, the opioids were titrated to maintain heart rate and mean arterial pressure within 20% of baseline, and propofol was titrated to keep the bispectral index (BIS) less than 60. Neuromuscular blockade was achieved with succinylcholine. Drug dosages and the times from cessation of anesthesia to extubation, verbal response, recovery of ventilation, and neuropsychological testing, orientation, and discharge readiness were recorded. Results Demographics, duration of surgery, and anesthesia were similar between the two groups. Both groups received similar propofol doses. There were no difference in BIS values preoperatively (mean, 96), intraoperatively (mean, 55), and postoperatively (mean, 96). Recovery of BIS and times for verbal response did not differ. At 20, 30, and 40 min after terminating the opioid infusion, the peripheral oxygen saturation and respiratory rate were significantly higher in the remifentanil group compared with the alfentanil group. Conclusions When both the hypnotic and analgesic components of a TIVA-based anesthetic are administered in equipotent doses, remifentanil provides a more rapid respiratory recovery, even after brief surgical procedures, compared with alfentanil.

UNLABELLED This study examines the effect of spinal ibuprofen on the behavioral manifestations associated with the opioid abstinence syndrome. Rats (n = 8 per group) were infused for 5 days with morphine and then pretreated with a spinal bolus dose of ibuprofen before systemic naloxone antagonism (300 microg). Groups included ibuprofen S(+) 1. 36, 13.6, and 136 nmol, and ibuprofen R(-) 136 nmol. A separate group of saline-infused rats was given ibuprofen S(+) 136 nmol before naloxone antagonism. Ibuprofen S(+), but not R(-), dose-dependently and stereospecifically blocked opioid withdrawal hyperalgesia but did not significantly alter other signs of the opioid abstinence syndrome. We conclude that hyperalgesia associated with opioid withdrawal can be blocked by spinally administered ibuprofen, and suggest that there may be a role for spinal prostaglandins in the enhancement of nociception observed in association with the opioid abstinence syndrome. IMPLICATIONS This study shows that spinal ibuprofen blocks opioid withdrawal hyperalgesia in the rat in a stereospecific fashion, implicating the likely release of spinal prostaglandins during withdrawal and their possible role as neuromodulators in the enhancement of nociception that accompanies this phenomenon.

UNLABELLED The aim of this prospective, randomized, double-blinded study was to compare pain relief, side effects, and ability to ambulate during epidural anesthesia with ropivacaine 0.2% plus sufentanil versus bupivacaine 0.175% plus sufentanil after major gastrointestinal surgery. Epidural catheters were inserted at T8-11, and 30 microg of sufentanil with 15 mL of ropivacaine 0.75% (Group 1, n = 42) or bupivacaine 0.5% (Group 2, n = 44) was injected. General anesthesia was induced, a continuous epidural infusion (5 mL/h) was then begun with 1 microg/mL sufentanil plus ropivacaine 0.2% (Group 1) or bupivacaine 0.175% (Group 2). Postoperatively, the infusion rate was adjusted to individual requirements. Patients were also able to receive additional 2-mL bolus doses every 20 min. Demographic data (except for gender and height), analgesia, drug dosage, and side-effects, including motor blockade (Bromage score), were similar in both groups, but mobilization recovered more quickly in Group 1. Gender, age, ASA physical status, duration of surgery, and intraoperative blood loss had no effect on mobilization. We conclude that epidural analgesia is effective and safe with both regimens. There is not necessarily a correlation between the Bromage score and the desired outcome of mobilization. The ability to walk postoperatively is hastened if ropivacaine is used instead of bupivacaine. IMPLICATIONS Regarding pain relief and side effects, epidural analgesia with ropivacaine 0.2% and sufentanil 1 microg/mL yields pain scores and pain intensity comparable to those for the well evaluated combination of bupivacaine 0.175% and sufentanil 1 microg/mL. However, earlier recovery of the ability to walk unassisted in patients receiving the combination of ropivacaine and sufentanil may result in their earlier rehabilitation.

Ischemic and traumatic brain injury is associated with increased risk for death and disability. The inhibition of penumbral tissue damage has been recognized as a target for therapeutic intervention, because cellular injury evolves progressively upon ATP-depletion and loss of ion homeostasis. In patients, thiopental is used to treat refractory intracranial hypertension by reducing intracranial pressure and cerebral metabolic demands; however, therapeutic benefits of thiopental-treatment are controversially discussed. In the present study we identified fundamental neuroprotective molecular mechanisms mediated by thiopental. Here we show that thiopental inhibits global protein synthesis, which preserves the intracellular energy metabolite content in oxygen-deprived human neuronal SK-N-SH cells or primary mouse cortical neurons and thus ameliorates hypoxic cell damage. Sensitivity to hypoxic damage was restored by pharmacologic repression of eukaryotic elongation factor 2 kinase. Translational inhibition was mediated by calcium influx, activation of the AMP-activated protein kinase, and inhibitory phosphorylation of eukaryotic elongation factor 2. Our results explain the reduction of cerebral metabolic demands during thiopental treatment. Cycloheximide also protected neurons from hypoxic cell death, indicating that translational inhibitors may generally reduce secondary brain injury. In conclusion our study demonstrates that therapeutic inhibition of global protein synthesis protects neurons from hypoxic damage by preserving energy balance in oxygen-deprived cells. Molecular evidence for thiopental-mediated neuroprotection favours a positive clinical evaluation of barbiturate treatment. The chemical structure of thiopental could represent a pharmacologically relevant scaffold for the development of new organ-protective compounds to ameliorate tissue damage when oxygen availability is limited.

Oxygen deprivation during ischemic or hemorrhagic stroke results in ATP depletion, loss of ion homeostasis, membrane depolarization, and excitotoxicity. Pharmacologic restoration of cellular energy supply may offer a promising concept to reduce hypoxic cell injury. In this study, we investigated whether carbimazole, a thionamide used to treat hyperthyroidism, reduces neuronal cell damage in oxygen-deprived human SK-N-SH cells or primary cortical neurons. Our results revealed that carbimazole induces an inhibitory phosphorylation of eukaryotic elongation factor 2 (eEF2) that was associated with a marked inhibition of global protein synthesis. Translational inhibition resulted in significant bioenergetic savings, preserving intracellular ATP content in oxygen-deprived neuronal cells and diminishing hypoxic cellular damage. Phosphorylation of eEF2 was mediated by AMP-activated protein kinase and eEF2 kinase. Carbimazole also induced a moderate calcium influx and a transient cAMP increase. To test whether translational inhibition generally diminishes hypoxic cell damage when ATP availability is limiting, the translational repressors cycloheximide and anisomycin were used. Cycloheximide and anisomycin also preserved ATP content in hypoxic SK-N-SH cells and significantly reduced hypoxic neuronal cell damage. Taken together, these data support a causal relation between the pharmacologic inhibition of global protein synthesis and efficient protection of neurons from ischemic damage by preservation of high-energy metabolites in oxygen-deprived cells. Furthermore, our results indicate that carbimazole or other translational inhibitors may be interesting candidates for the development of new organ-protective compounds. Their chemical structure may be used for computer-assisted drug design or screening of compounds to find new agents with the potential to diminish neuronal damage under ATP-limited conditions.

Background Lipid soluble mu opioids given intrathecally produce a potent, dose-dependent analgesic response, which because of rapid clearance, is of short duration. Such agents delivered by continuous infusion can result in systemic accumulation and significant extraspinally mediated side effects. The effects of intrathecal infusions of two lipid-soluble mu opioids were investigated: remifentanil, an esterase metabolized agent with an inactive metabolite, and alfentanil. Methods Rats with chronic lumbar intrathecal catheters received intrathecal infusions (in flow rates of 1.0 microliters/min and 0.1 microliters/min) of remifentanil or alfentanil and were tested for hind paw thermal withdrawal latency, supraspinal side effects (sedation, block of pinna, and corneal responses) and motor impairment. Remifentanil was delivered either in a glycine formulation (R(g)) or in a saline vehicle (R(s)). Separate studies with the glycine vehicle also were undertaken. Results At an infusion rate of 0.1 microliters/min, remifentanil and alfentanil produced naloxone-reversible, dose-dependent analgesia and supraspinal side effects with the intrathecal ED(50) (micrograms/min; 95% confidence interval) for analgesia: R(s) = 1.5 (1.2-1.8), R(g) = 1.2 (0.7-2.3); alfentanil = 1.5 (1.4-1.6) and for supraspinal side effects: R(s) = 1.7 (1.4-1.9); R(g) = 1.9 (1.6-2.4); alfentanil = 1.5 (1.4-1.7). There was no difference in potency or time until onset for analgesia at either delivery rate (12-20 min), whereas for supraspinal side effects, 1.0 microliters/min resulted in a faster onset for R(g). Recovery of normal thresholds after equianalgesic doses was faster in R(s) than alfentanil and for the supraspinal index faster in R(s) and R(g) groups. R(g), but not R(s), or alfentanil, produced a dose-dependent motor impairment after 90 min of intrathecal infusion at a flow rate of 0.1 microliters/min. Both glycine in R(g) and glycine (matching glycine dose) alone showed parallel time courses for motor impairment and similar intrathecal ED(50) (6.6 vs. 6.4 micrograms/min over 90 min) for this nonnaloxone reversible effect. Intrathecal bolus administration of the same total dose of glycine showed no significant motor effects. Conclusions Remifentanil has a rapid onset like alfentanil but shows a faster recovery of action after intrathecal infusion. Despite its rapid clearance, remifentanil induces supraspinal side effects at analgesic effective doses. Moreover, in the current formulation, with glycine, a reversible motor impairment can occur after intrathecal delivery.