Epidural analgesia and neonatal short-term outcomes during routine childbirth: a 10-year retrospective analysis from the national birth registry of Austria.

BACKGROUND: Epidural analgesia (EA) is well-accepted for pain relief during labor. Still, the impact on neonatal short-term outcome is under continuous debate. This study assessed the outcome of neonates in deliveries with and without EA in a nationwide cohort. METHODS: We analyzed the National Birth Registry of Austria between 2008 and 2017 of primiparous women with vaginal birth of singleton pregnancies. Neonatal short-term morbidity was assessed by arterial cord pH and base excess (BE). Secondary outcomes were admission to a neonatological intensive care unit, APGAR scores, and perinatal mortality. Propensity score-adjusted regression models were used to investigate the association of EA with short-term neonatal outcome. RESULTS: Of 247,536 included deliveries, 52 153 received EA (21%). Differences in pH (7.24 vs. 7.25; 97.5% CI -0.0066 to -0.0047) and BE (-5.89±3.2 vs. -6.15±3.2 mmol/L; 97.5% CI 0.32 to 0.40) with EA could be shown. APGAR score at five minutes <7 was more frequent with EA (OR 1.45; 95% CI: 1.29 to 1.63). Admission to a neonatological intensive care unit occurred more often with EA (4.7% vs. 3.4%) with an OR for EA of 1.2 (95% CI: 1.14 to 1.26). EA was not associated with perinatal mortality (OR 1.33; 95% CI: 0.79 to 2.25). CONCLUSIONS: EA showed no clinically relevant association with neonatal short-term outcome. Higher rates of NICU admission and APGAR score after five minutes <7 were observed with EA. The overall use of EA in Austria is low, and an investigation of causes may be indicated.

The Proteome of Extracellular Vesicles Released from Pulmonary Microvascular Endothelium Reveals Impact of Oxygen Conditions on Biotrauma.

The lung can experience different oxygen concentrations, low as in hypoxia, high as under supplemental oxygen therapy, or oscillating during intermittent hypoxia as in obstructive sleep apnea or intermittent hypoxia/hyperoxia due to cyclic atelectasis in the ventilated patient. This study aimed to characterize the oxygen-condition-specific protein composition of extracellular vesicles (EVs) released from human pulmonary microvascular endothelial cells in vitro to decipher their potential role in biotrauma using quantitative proteomics with bioinformatic evaluation, transmission electron microscopy, flow cytometry, and non-activated thromboelastometry (NATEM). The release of vesicles enriched in markers CD9/CD63/CD81 was enhanced under intermittent hypoxia, strong hyperoxia and intermittent hypoxia/hyperoxia. Particles with exposed phosphatidylserine were increased under intermittent hypoxia. A small portion of vesicles were tissue factor-positive, which was enhanced under intermittent hypoxia and intermittent hypoxia/hyperoxia. EVs from treatment with intermittent hypoxia induced a significant reduction of Clotting Time in NATEM analysis compared to EVs isolated after normoxic exposure, while after intermittent hypoxia/hyperoxia, tissue factor in EVs seems to be inactive. Gene set enrichment analysis of differentially expressed genes revealed that EVs from individual oxygen conditions potentially induce different biological processes such as an inflammatory response under strong hyperoxia and intermittent hypoxia/hyperoxia and enhancement of tumor invasiveness under intermittent hypoxia.

Blood-brain Barrier Permeability May Influence Vasopressor Effects in Anesthetized Patients With Brain Tumor: An Analysis of Magnetic Resonance Imaging Data.

OBJECTIVE: This is a secondary analysis of data from a previous study of anesthetized brain tumor patients receiving ephedrine or phenylephrine infusions. 18 patients with magnetic imaging verified tumor contrast enhancement were included. We hypothesized that vasopressors induce microcirculatory flow changes, characterized by increased capillary transit time heterogeneity (CTH) and decreased mean transit time (MTT), in brain regions exhibiting BBB leakage. METHODS: This is a secondary analysis of data from a previous study of anesthetized brain tumor patients receiving ephedrine or phenylephrine infusions. 18 patients with magnetic imaging verified tumor contrast enhancement were included. Postvasopressor to prevasopressor ratios of CTH, MTT, relative transit time heterogeneity (RTH), cerebral blood flow (CBF), cerebral blood volume, and oxygen extraction fraction (OEF) were calculated in tumor, peritumoral, hippocampal, and contralateral grey matter regions. Comparisons were made between brain regions and vasopressors. RESULTS: During phenylephrine infusion, ratios of CTH, RTH, and CBF were greater, and ratios of MTT and OEF were lower, in the tumor region with contrast leakage compared with corresponding contralateral grey matter ratios. During ephedrine infusion, ratios of CTH, MTT, RTH, CBF, and cerebral blood volume were higher in the tumor region with leakage compared with contralateral grey matter ratios. In addition, the ratio of CBF was higher in all regions, the ratio of RTH was lower in the leaking tumor region, and the ratio of OEF was lower in peritumoral, hippocampal, and grey matter regions with ephedrine compared with phenylephrine. CONCLUSIONS: Vasopressors can induce distinct microcirculatory flow alterations in regions with compromised brain tumor barrier or BBB. Ephedrine, a combined α and ß-adrenergic agonist, appears to result in fewer flow alterations and less impact on tissue oxygenation compared with phenylephrine, a pure α-adrenergic agonist.

Dataset of 143 metagenome-assembled genomes from the Arctic and Atlantic Oceans, including 21 for eukaryotic organisms.

This article presents metagenome-assembled genomes (MAGs) for both eukaryotic and prokaryotic organisms originating from the Arctic and Atlantic oceans, along with gene prediction and functional annotation for MAGs from both domains. Eleven samples from the chlorophyll-a maximum layer of the surface ocean were collected during two cruises in 2012; six from the Arctic in June-July on ARK-XXVII/1 (PS80), and five from the Atlantic in November on ANT-XXIX/1 (PS81). Sequencing and assembly was carried out by the Joint Genome Institute (JGI), who provide annotation of the assembled sequences, and 122 MAGs for prokaryotic organisms. A subsequent binning process identified 21 MAGs for eukaryotic organisms, mostly identified as Mamiellophyceae or Bacillariophyceae. The data for each MAG includes sequences in FASTA format, and tables of functional annotation of genes. For eukaryotic MAGs, transcript and protein sequences for predicted genes are available. A spreadsheet is provided summarising quality measures and taxonomic classifications for each MAG. These data provide draft genomes for uncultured marine microbes, including some of the first MAGs for polar eukaryotes, and can provide reference genetic data for these environments, or used in genomics-based comparison between environments.

Correlation Between Cerebral Tissue Oxygen Saturation and Oxygen Extraction Fraction During Anesthesia: Monitoring Cerebral Metabolic Demand-supply Balance During Vasopressor Administration.

BACKGROUND: The speculation that cerebral tissue oxygen saturation (SctO 2 ) measured using tissue near-infrared spectroscopy reflects the balance between cerebral metabolic rate of oxygen and cerebral oxygen delivery has not been validated. Our objective was to correlate SctO 2 with cerebral oxygen extraction fraction (OEF) measured using positron emission tomography; OEF is the ratio between cerebral metabolic rate of oxygen and cerebral oxygen delivery and reflects the balance between these 2 variables. MATERIALS AND METHODS: This cohort study was based on data collected in a previously published trial assessing phenylephrine versus ephedrine treatment in anesthetized patients undergoing brain tumor surgery. The variables of interest were measured twice over the healthy hemisphere before surgery: the first measurement performed after anesthesia induction and the second measurement performed after induction of a ∼20% increase in blood pressure using either phenylephrine or ephedrine. RESULTS: Data from 24 patients were analyzed. The overall vasopressor-induced relative changes in SctO 2 (ΔSctO 2 ) and OEF (ΔOEF) were 3.16% [interquartile range, -0.73% to 6.04%] and -12.5% [interquartile range, -24.0% to -6.19%], respectively. ΔSctO 2 negatively correlated with ΔOEF after phenylephrine treatment (Spearman rank correlation coefficient [ rs ]=-0.76; P =0.007), ephedrine treatment ( rs =-0.76; P =0.006), and any treatment ( rs =-0.79; P <0.001). ΔSctO 2 significantly associated with ΔOEF based on multivariable analysis with ΔOEF, relative changes in mean arterial pressure, arterial blood oxygen tension, and the bispectral index as covariates ( P =0.036). CONCLUSIONS: The negative correlation between changes in SctO 2 and OEF suggests that SctO 2 may reflect the cerebral metabolic demand-supply balance during vasopressor treatment. The generalizability of our findings in other clinical scenarios remains to be determined.

Metagenome-assembled genomes of phytoplankton microbiomes from the Arctic and Atlantic Oceans.

BACKGROUND: Phytoplankton communities significantly contribute to global biogeochemical cycles of elements and underpin marine food webs. Although their uncultured genomic diversity has been estimated by planetary-scale metagenome sequencing and subsequent reconstruction of metagenome-assembled genomes (MAGs), this approach has yet to be applied for complex phytoplankton microbiomes from polar and non-polar oceans consisting of microbial eukaryotes and their associated prokaryotes. RESULTS: Here, we have assembled MAGs from chlorophyll a maximum layers in the surface of the Arctic and Atlantic Oceans enriched for species associations (microbiomes) with a focus on pico- and nanophytoplankton and their associated heterotrophic prokaryotes. From 679 Gbp and estimated 50 million genes in total, we recovered 143 MAGs of medium to high quality. Although there was a strict demarcation between Arctic and Atlantic MAGs, adjacent sampling stations in each ocean had 51-88% MAGs in common with most species associations between Prasinophytes and Proteobacteria. Phylogenetic placement revealed eukaryotic MAGs to be more diverse in the Arctic whereas prokaryotic MAGs were more diverse in the Atlantic Ocean. Approximately 70% of protein families were shared between Arctic and Atlantic MAGs for both prokaryotes and eukaryotes. However, eukaryotic MAGs had more protein families unique to the Arctic whereas prokaryotic MAGs had more families unique to the Atlantic. CONCLUSION: Our study provides a genomic context to complex phytoplankton microbiomes to reveal that their community structure was likely driven by significant differences in environmental conditions between the polar Arctic and warm surface waters of the tropical and subtropical Atlantic Ocean. Video Abstract.

The biogeographic differentiation of algal microbiomes in the upper ocean from pole to pole.

Eukaryotic phytoplankton are responsible for at least 20% of annual global carbon fixation. Their diversity and activity are shaped by interactions with prokaryotes as part of complex microbiomes. Although differences in their local species diversity have been estimated, we still have a limited understanding of environmental conditions responsible for compositional differences between local species communities on a large scale from pole to pole. Here, we show, based on pole-to-pole phytoplankton metatranscriptomes and microbial rDNA sequencing, that environmental differences between polar and non-polar upper oceans most strongly impact the large-scale spatial pattern of biodiversity and gene activity in algal microbiomes. The geographic differentiation of co-occurring microbes in algal microbiomes can be well explained by the latitudinal temperature gradient and associated break points in their beta diversity, with an average breakpoint at 14 °C ± 4.3, separating cold and warm upper oceans. As global warming impacts upper ocean temperatures, we project that break points of beta diversity move markedly pole-wards. Hence, abrupt regime shifts in algal microbiomes could be caused by anthropogenic climate change.

Cerebral microemboli during extracorporeal life support: a single-centre cohort study.

OBJECTIVES: The aim of this study was to investigate the load and composition of cerebral microemboli in adult patients undergoing venoarterial extracorporeal life support (ECLS). METHODS: Adult ECLS patients were investigated for the presence of cerebral microemboli and compared to critically ill, pressure-controlled ventilated controls and healthy volunteers. Cerebral microemboli were detected in both middle cerebral arteries for 30 min using transcranial Doppler ultrasound. Neurological outcome (ischaemic stroke, global brain ischaemia, intracerebral haemorrhage, seizure, metabolic encephalopathy, sensorimotor sequelae and neuropsychiatric disorders) was additionally evaluated. RESULTS: Twenty ECLS patients (cannulations: 15 femoro-femoral, 4 femoro-subclavian, 1 femoro-aortic), 20 critically ill controls and 20 healthy volunteers were analysed. ECLS patients had statistically significantly more cerebral microemboli than critically ill controls {123 (43-547) [median (interquartile range)] vs 35 (16-74), difference: 88 [95% confidence interval (CI) 19-320], P = 0.023} and healthy volunteers [11 (5-12), difference: 112 (95% CI 45-351), P < 0.0001]. In ECLS patients, 96.5% (7346/7613) of cerebral microemboli were of gaseous composition, while solid cerebral microemboli [1 (0-5)] were detected in 12 out of 20 patients. ECLS patients had more neurological complications than critically ill controls (12/20 vs 3/20, P = 0.003). In ECLS patients, a high microembolic rate (>100/30 min) tended to be associated with neurological complications including ischaemic stroke, neuropsychiatric disorders, sensorimotor sequelae and non-convulsive status epilepticus (odds ratio 4.5, 95% CI 0.46-66.62; P = 0.559). CONCLUSIONS: Our results indicate that adult ECLS patients are continuously exposed to many gaseous and, frequently, to few solid cerebral microemboli. Prolonged cerebral microemboli formation may contribute to neurological morbidity related to ECLS treatment. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT02020759, https://clinicaltrials.gov/ct2/show/NCT02020759?term=erdoes&rank=1.

Cerebral Macro- and Microcirculation during Ephedrine versus Phenylephrine Treatment in Anesthetized Brain Tumor Patients: A Randomized Clinical Trial Using Magnetic Resonance Imaging.

BACKGROUND: This study compared ephedrine versus phenylephrine treatment on cerebral macro- and microcirculation, measured by cerebral blood flow, and capillary transit time heterogeneity, in anesthetized brain tumor patients. The hypothesis was that capillary transit time heterogeneity in selected brain regions is greater during phenylephrine than during ephedrine, thus reducing cerebral oxygen tension. METHODS: In this single-center, double-blinded, randomized clinical trial, 24 anesthetized brain tumor patients were randomly assigned to ephedrine or phenylephrine. Magnetic resonance imaging of peritumoral and contralateral hemispheres was performed before and during vasopressor infusion. The primary endpoint was between-group difference in capillary transit time heterogeneity. Secondary endpoints included changes in cerebral blood flow, estimated oxygen extraction fraction, and brain tissue oxygen tension. RESULTS: Data from 20 patients showed that mean (± SD) capillary transit time heterogeneity in the contralateral hemisphere increased during phenylephrine from 3.0 ± 0.5 to 3.2 ± 0.7 s and decreased during ephedrine from 3.1 ± 0.8 to 2.7 ± 0.7 s (difference phenylephrine versus difference ephedrine [95% CI], -0.6 [-0.9 to -0.2] s; P = 0.004). In the peritumoral region, the mean capillary transit time heterogeneity increased during phenylephrine from 4.1 ± 0.7 to 4.3 ± 0.8 s and decreased during ephedrine from 3.5 ± 0.9 to 3.3 ± 0.9 s (difference phenylephrine versus difference ephedrine [95%CI], -0.4[-0.9 to 0.1] s; P = 0.130). Cerebral blood flow (contralateral hemisphere ratio difference [95% CI], 0.3 [0.06 to 0.54]; P = 0.018; and peritumoral ratio difference [95% CI], 0.3 [0.06 to 0.54; P = 0.018) and estimated brain tissue oxygen tension (contralateral hemisphere ratio difference [95% CI], 0.34 [0.09 to 0.59]; P = 0.001; and peritumoral ratio difference [95% CI], 0.33 [0.09 to 0.57]; P = 0.010) were greater during ephedrine than phenylephrine in both regions. CONCLUSIONS: Phenylephrine caused microcirculation in contralateral tissue, measured by the change in capillary transit time heterogeneity, to deteriorate compared with ephedrine, despite reaching similar mean arterial pressure endpoints. Ephedrine improved cerebral blood flow and tissue oxygenation in both brain regions and may be superior to phenylephrine in improving cerebral macro- and microscopic hemodynamics and oxygenation.

Ephedrine versus Phenylephrine Effect on Cerebral Blood Flow and Oxygen Consumption in Anesthetized Brain Tumor Patients: A Randomized Clinical Trial.

BACKGROUND: Studies in anesthetized patients suggest that phenylephrine reduces regional cerebral oxygen saturation compared with ephedrine. The present study aimed to quantify the effects of phenylephrine and ephedrine on cerebral blood flow and cerebral metabolic rate of oxygen in brain tumor patients. The authors hypothesized that phenylephrine reduces cerebral metabolic rate of oxygen in selected brain regions compared with ephedrine. METHODS: In this double-blinded, randomized clinical trial, 24 anesthetized patients with brain tumors were randomly assigned to ephedrine or phenylephrine treatment. Positron emission tomography measurements of cerebral blood flow and cerebral metabolic rate of oxygen in peritumoral and normal contralateral regions were performed before and during vasopressor infusion. The primary endpoint was between-group difference in cerebral metabolic rate of oxygen. Secondary endpoints included changes in cerebral blood flow, oxygen extraction fraction, and regional cerebral oxygen saturation. RESULTS: Peritumoral mean ± SD cerebral metabolic rate of oxygen values before and after vasopressor (ephedrine, 67.0 ± 11.3 and 67.8 ± 25.7 µmol · 100 g · min; phenylephrine, 68.2 ± 15.2 and 67.6 ± 18.0 µmol · 100 g · min) showed no intergroup difference (difference [95% CI], 1.5 [-13.3 to 16.3] µmol · 100 g · min [P = 0.839]). Corresponding contralateral hemisphere cerebral metabolic rate of oxygen values (ephedrine, 90.8 ± 15.9 and 94.6 ± 16.9 µmol · 100 g · min; phenylephrine, 100.8 ± 20.7 and 96.4 ± 17.7 µmol · 100 g · min) showed no intergroup difference (difference [95% CI], 8.2 [-2.0 to 18.5] µmol · 100 g · min [P = 0.118]). Ephedrine significantly increased cerebral blood flow (difference [95% CI], 3.9 [0.7 to 7.0] ml · 100 g · min [P = 0.019]) and regional cerebral oxygen saturation (difference [95% CI], 4 [1 to 8]% [P = 0.024]) in the contralateral hemisphere compared to phenylephrine. The change in oxygen extraction fraction in both regions (peritumoral difference [95% CI], -0.6 [-14.7 to 13.6]% [P = 0.934]; contralateral hemisphere difference [95% CI], -0.1 [- 12.1 to 12.0]% [P = 0.989]) were comparable between groups. CONCLUSIONS: The cerebral metabolic rate of oxygen changes in peritumoral and normal contralateral regions were similar between ephedrine- and phenylephrine-treated patients. In the normal contralateral region, ephedrine was associated with an increase in cerebral blood flow and regional cerebral oxygen saturation compared with phenylephrine.

Effects of Vasopressors on Cerebral Circulation and Oxygenation: A Narrative Review of Pharmacodynamics in Health and Traumatic Brain Injury.

The clinical use of vasoactive drugs aims to improve hemodynamic variables and thereby maintain or restore adequate perfusion and oxygenation in accordance with metabolic demands. A main focus in the management of patients with brain pathology during surgery and neurointensive care is restoring and/or maintaining adequate cerebral perfusion pressure in order to ensure cerebral blood flow in accordance with metabolic demands. One commonly used clinical strategy is the administration of vasoactive drugs aiming to increase mean arterial blood pressure and thereby cerebral perfusion pressure. Here, we first describe the anatomic and physiological basis for the cerebrovascular effects of vasopressor agents. Next, we review the pharmacodynamics of commonly used vasopressors under normal circumstances and in the presence of head injury. We further discuss the role of blood-brain barrier disruption and microvascular dysfunction with regard to the effects of the reviewed vasopressor agents.

Ropivacaine Activates Multiple Proapoptotic and Inflammatory Signaling Pathways That Might Subsume to Trigger Epidural-Related Maternal Fever.

BACKGROUND: Epidural-related maternal fever (ERMF) is an adverse effect of epidural analgesia during labor and is associated with perinatal and neonatal morbidity. Local anesthetics have been proposed to trigger ERMF via sterile inflammation. Ropivacaine is currently the most frequently used epidural anesthetic and considered least toxic. This study investigates molecular effects of ropivacaine on human umbilical vein endothelial cells (HUVECs) as model system for endothelial cells and human placental trophoblasts (TBs), compares the effects to the putative anti-inflammatory lidocaine and investigates the partially alleviating impact of the anti-inflammatory corticosteroid dexamethasone. METHODS: HUVECs and TBs were exposed to ropivacaine (35 µM-7 mM) or lidocaine (21 mM) with or without dexamethasone (1 µM). AnnexinV/propidium iodide staining and lactate dehydrogenase release were used to analyze apoptosis and cytotoxicity. Proinflammatory interleukins-6 (IL-6) and IL-8 as well as prostaglandin E2 (PGE2) were measured by enzyme-linked immunosorbent assay (ELISA), while activation of signaling pathways was detected by Western blotting. Oxidative stress was visualized by live cell imaging and quantification of antioxidant proteins, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, platelet endothelial cell adhesion molecule 1, cyclooxygenase 2, and mitochondrial deoxyribonucleic acid by real-time polymerase chain reaction. Dissipation of the mitochondrial membrane potential was assessed with cytofluorimetric analysis using the J-Aggregate (JC-1 staining [cytofluorimetric analysis using the J-Aggregate]). RESULTS: Ropivacaine exposure dose-dependently induced apoptosis and an increased release of IL-6, IL-8, and PGE2 from HUVECs and TBs. Furthermore, caspase-3, nuclear factor-κB, and p38 mitogen-activated protein kinase pathways were activated, while extracellular signal-regulated kinase 1/2 and protein kinase B (Akt) were dephosphorylated. Downregulation of antioxidative proteins induced oxidative stress and upregulation of ICAM1, VCAM1, and PECAM1 possibly facilitate leukocyte transmigration. Mitochondrial effects included increased release of the proinflammatory mitochondrial DNA damage-associated molecular patterns, but no significant dissipation of the mitochondrial membrane potential. Conversely, lidocaine exhibited repression of IL-6 and IL-8 release over all time points, and early downregulation of COX2 and cell adhesion molecules, which was followed by a late overshooting reaction. Dexamethasone reduced especially inflammatory effects, but as an inducer of mitophagy, had negative long-term effects on mitochondrial function. CONCLUSIONS: This study suggests that ropivacaine causes cellular injury and death in HUVECs and TBs via different signaling pathways. The detrimental effects induced by ropivacaine are only partially blunted by dexamethasone. This observation strengthens the importance of inflammation in ERMF.

Epigenetic modulation of tenascin C in the heart: implications on myocardial ischemia, hypertrophy and metabolism.

BACKGROUND: Tenascin C (TN-C) is considered to play a pathophysiological role in maladaptive left ventricular remodeling. Yet, the mechanism underlying TN-C-dependent cardiac dysfunction remains elusive. METHOD: The present study was designed to investigate the effect of hypoxia and hypertrophic stimuli on TN-C expression in H9c2 cells and its putative regulation by epigenetic mechanisms, namely DNA promoter methylation and microRNAs. In addition, rats subjected to myocardial infarction (MI) were investigated. H9c2 cells were subjected to oxygen and glucose deprivation; incubated with angiotensin II (Ang II); or human TN-C (hTN-C) purified protein. Hypertrophic and fibrotic markers, TN-C promoter methylation as well as mir-335 expression were assessed by reverse transcription and quantitative polymerase chain reaction while TN-C protein levels were assessed by ELISA. RESULTS: Tn-C mRNA expression was markedly increased by both oxygen and glucose deprivation and Ang II (P < 0.01, respectively). In addition, Ang-II-dependent TN-C upregulation was explained by reduced promoter methylation (P < 0.05). Cells treated with hTN-C displayed upregulation of Bnp, Mmp2, ß-Mhc, integrin α6 and integrin ß1. Furthermore, hTN-C treated cells showed a significant reduction in adenosine monophosphate and adenosine triphosphate levels. In vivo, plasma and myocardial TN-C levels were increased 7 days post MI (P < 0.05, respectively). This increment in TN-C was accompanied by upregulation of mir-335 (P < 0.01). In conclusion, both hypoxic and hypertrophic stimuli lead to epigenetically driven TN-C upregulation and subsequent impairment of cellular energy metabolism in cardiomyoblasts. CONCLUSION: These findings might enlighten our understanding on maladaptive left ventricular remodeling and direct towards a strong involvement of TN-C.

PO2 oscillations induce lung injury and inflammation.

BACKGROUND: Mechanical ventilation can lead to ventilator-induced lung injury (VILI). In addition to the well-known mechanical forces of volutrauma, barotrauma, and atelectrauma, non-mechanical mechanisms have recently been discussed as contributing to the pathogenesis of VILI. One such mechanism is oscillations in partial pressure of oxygen (PO2) which originate in lung tissue in the presence of within-breath recruitment and derecruitment of alveoli. The purpose of this study was to investigate this mechanism's possible independent effects on lung tissue and inflammation in a porcine model. METHODS: To separately study the impact of PO2 oscillations on the lungs, an in vivo model was set up that allowed for generating mixed-venous PO2 oscillations by the use of veno-venous extracorporeal membrane oxygenation (vvECMO) in a state of minimal mechanical stress. While applying the identical minimal-invasive ventilator settings, 16 healthy female piglets (weight 50 ± 4 kg) were either exposed for 6 h to a constant mixed-venous hemoglobin saturation (SmvO2) of 65% (which equals a PmvO2 of 41 Torr) (control group), or an oscillating SmvO2 (intervention group) of 40-90% (which equals PmvO2 oscillations of 30-68 Torr)-while systemic normoxia in both groups was maintained. The primary endpoint of histologic lung damage was assessed by ex vivo histologic lung injury scoring (LIS), the secondary endpoint of pulmonary inflammation by qRT-PCR of lung tissue. Cytokine concentration of plasma was carried out by ELISA. A bioinformatic microarray analysis of lung samples was performed to generate hypotheses about underlying pathomechanisms. RESULTS: The LIS showed significantly more severe damage of lung tissue after exposure to PO2 oscillations compared to controls (0.53 [0.51; 0.58] vs. 0.27 [0.23; 0.28]; P = 0.0025). Likewise, a higher expression of TNF-α (P = 0.0127), IL-1ß (P = 0.0013), IL-6 (P = 0.0007), and iNOS (P = 0.0013) in lung tissue was determined after exposure to PO2 oscillations. Cytokines in plasma showed a similar trend between the groups, however, without significant differences. Results of the microarray analysis suggest that inflammatory (IL-6) and oxidative stress (NO/ROS) signaling pathways are involved in the pathology linked to PO2 oscillations. CONCLUSIONS: Artificial mixed-venous PO2 oscillations induced lung damage and pulmonary inflammation in healthy animals during lung protective ventilation. These findings suggest that PO2 oscillations represent an independent mechanism of VILI.

Impact of CPAP on Forehead Near-infrared Spectroscopy Measurements in Patients With Acute Respiratory Failure: Truth or Illusion.

BACKGROUND: Critically ill patients with acute respiratory failure admitted to an intensive care unit are at high risk for cerebral hypoxia. We investigated the impact of continuous positive airway pressure (CPAP) therapy on regional cerebral tissue oxygenation (rSO2). MATERIALS AND METHODS: In total, 40 extubated surgical intensive care unit patients requiring classic oxygen therapy (COT) for acute respiratory failure were examined. Near-infrared spectroscopy (INVOS 5100C, Covidien) was used for 30 minutes to detect bilateral rSO2 during COT via facemask (6 L/min) and CPAP therapy (40% fraction of inspired oxygen, 8 cm H2O CPAP) using a randomized crossover study design. Patients served as their own control. Continuous hemodynamic routine monitoring and blood gas analysis were performed. The effect of CPAP therapy on rSO2 and influence of assessed covariables were investigated using a mixed linear model. RESULTS: Median rSO2 increased from 57.9% (95% confidence interval [CI], 54.2-61.5) during COT to 62.8% (95% CI, 59.2-66.5) during CPAP therapy (P<0.0001). The estimated difference from the mixed model between COT and CPAP is -5.0 (95% CI, -6.3 to -3.7). Median arterial partial pressure of carbon dioxide decreased from 47.8±5.1 mm Hg during COT to 43.1±5 mm Hg during CPAP (P<0.001), whereas arterial partial pressure of oxygen remained unchanged (P=0.329). In total, 23% of patients had SO2 levels <50%, with a higher prevalence under COT. CONCLUSIONS: Our results reveal that CPAP therapy compared with COT may influence rSO2 in patients with acute respiratory failure. However, the cause of the rSO2 increase following CPAP application remains to be elucidated, and the accuracy of cerebral oximetry during CPAP therapy in patients with acute respiratory failure remains questionable.

Pretreatment With Argon Protects Human Cardiac Myocyte-Like Progenitor Cells from Oxygen Glucose Deprivation-Induced Cell Death by Activation of AKT and Differential Regulation of Mapkinases.

BACKGROUND: The noble gas argon induces cardioprotection in a rabbit model of myocardial ischemia and reperfusion. However, no studies in human primary cells or subjects have been performed so far. We used human cardiac myocyte-like progenitor cells (HCMs) to investigate the protective effect on the cellular level. METHODS: HCMs were pretreated with 30% or 50% argon before oxygen-glucose deprivation (OGD) and reperfusion. We evaluated apoptotic states by flow cytometry and the activation of mitogen-activated protein kinase (MAPKs) members extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), p38 MAPkinase, and protein kinase B (Akt) by Westernblot analysis and by activity assays of downstream transcription factors. Specific inhibitors were used to proof a significant participation of these pathways in the protection by argon. Beneficial effects were further assessed by TdT-mediated dUTP-biotin nick end labeling (TUNEL) assay, lactate dehydrogenase (LDH), mitochondrial deoxyribonucleic acid (mtDNA), and cytokine release. RESULTS: Pretreatment with 30% or 50% argon for 90 min before OGD resulted in a significant protection of HCMs against apoptosis. This effect was reversed by the application of MAPK and Akt inhibitors during argon exposure. Argon 30% reduced the release of LDH by 33% and mtDNA by 45%. The release of interleukin 1ß was reduced by 44% after OGD and more than 90% during reperfusion. CONCLUSIONS: Pretreatment with argon protects HCMs from apoptosis under ischemic conditions via activation of Akt, Erk, and biphasic regulation of JNK. Argon gas is cheap and easily administrable, and might be a novel therapy to reduce myocardial ischemia-reperfusion injury.

Tenascin-C promotes chronic pressure overload-induced cardiac dysfunction, hypertrophy and myocardial fibrosis.

AIMS: Left ventricular (LV) hypertrophy is characterized by cardiomyocyte hypertrophy and interstitial fibrosis ultimately leading to increased myocardial stiffness and reduced contractility. There is substantial evidence that the altered expression of matrix metalloproteinases (MMP) and Tenascin-C (TN-C) are associated with the progression of adverse LV remodeling. However, the role of TN-C in the development of LV hypertrophy because of chronic pressure overload as well as the regulatory role of TN-C on MMPs remains unknown. METHODS AND RESULTS: In a knockout mouse model of TN-C, we investigated the effect of 10 weeks of pressure overload using transverse aortic constriction (TAC). Cardiac function was determined by magnetic resonance imaging. The expression of MMP-2 and MMP-9, CD147 as well as myocardial fibrosis were assessed by immunohistochemistry. The expression of TN-C was assessed by RT-qPCR and ELISA. TN-C knockout mice showed marked reduction in fibrosis (P < 0.001) and individual cardiomyocytes size (P < 0.01), in expression of MMP-2 (P < 0.05) and MMP-9 (P < 0.001) as well as preserved cardiac function (P < 0.01) in comparison with wild-type mice after 10 weeks of TAC. In addition, CD147 expression was markedly increased under pressure overload (P < 0.01), irrespectively of genotype. TN-C significantly increased the expression of the markers of hypertrophy such as ANP and BNP as well as MMP-2 in H9c2 cells (P < 0.05, respectively). CONCLUSION: Our results are pointed toward a novel signaling mechanism that contributes to LV remodeling via MMPs upregulation, cardiomyocyte hypertrophy as well as myocardial fibrosis by TN-C under chronic pressure overload.

Differences in Stem Cell Processing Lead to Distinct Secretomes Secretion-Implications for Differential Results of Previous Clinical Trials of Stem Cell Therapy for Myocardial Infarction.

Stem cell therapy for acute myocardial infarction (AMI) seemed to be a promising therapy, however, large clinical trials brought differential outcome. It has been shown that paracrine effects of secretomes of stem cells rather than cell therapy might play a fundamental role. The present study seeks to compare cell processing protocols of clinical trials and investigate effects of differential cell culture conditions on chemokine secretion and functional effects. Different secretomes are compared regarding IL-8, VEGF, MCP-1, and TNF-alpha secretion. Secretome mediated effects are evaluated on endothelial cell (HUVEC) tube formation and migration. Cardioprotective signaling kinases in human cardiomyocytes are determined by Western immunoblotting. Cells processed according to the REPAIR-AMI protocol secrete significantly higher amounts of IL-8 (487.3 ± 1231.1 vs 9.1 ± 8.2 pg mL-1 ; p < 0.05). REAPIR-AMI supernatants lead to significantly pronounced tube formation and migration on HUVEC and enhance the phosphorylation of Akt, ERK, and CREB. Cell processing conditions have a major impact on the composition of the secretome. The REPAIR-AMI secretome significantly enhances proangiogenic chemokine secretion, angiogenesis, cell migration, and cardioprotective signaling pathways. These results might explain differential outcomes between clinical trials. Optimizing cell processing protocols with special regards to paracrine factors, might open a new therapeutic concept for improving patient outcome.

Moderate hyperoxia induces inflammation, apoptosis and necrosis in human umbilical vein endothelial cells: An in-vitro study.

BACKGROUND: Perioperative oxygen (O2) therapy can cause hyperoxia. Extreme hyperoxia can injure the cardiovascular system and remote organs. OBJECTIVE: Our primary objective was to test the hypothesis that exposure to moderate hyperoxia will induce injury to human umbilical vein endothelial cells (HUVECs), a model for studying the vascular endothelium under controlled conditions. DESIGN: In-vitro cell culture study. SETTING: Department of Anaesthesia, General Intensive Care and Pain Management, Medical University of Vienna, Austria. Study period from the beginning of October 2013 to the end of July 2014. CELLS: HUVECs were isolated from fresh umbilical cords. INTERVENTIONS: HUVECs were exposed to constant hyperoxia (40% O2), cyclic hyperoxia/anoxia (40%/0% O2, average 20% O2), constant normoxia (21% O2) and constant anoxia (0% O2) using a cell culture bioreactor. MAIN OUTCOME MEASURES: Cell growth, viability and release of IL-6, IL-8 and macrophage migration inhibitory factor were assessed at baseline and after 6, 12, 24 and 48 h of treatment. A phosphokinase array was performed after 60 min of treatment to identify activated cellular signalling pathways. RESULTS: Constant hyperoxia and cyclic hyperoxia/anoxia impeded cell growth, reduced viability, triggered a proinflammatory response, proven by IL-6, IL-8 and migration inhibitory factor release, and induced apoptosis and necrosis. The inflammatory and cytotoxicity responses were highest in the constant hyperoxia group. Phosphokinase arrays revealed that different O2 concentrations activated distinct sets of cytoprotective and cell death-associated kinases, including mitogen-activated protein kinases, Src kinases, p53, Akt, mitogen-activated and stress-activated kinase, Lyn, Lck, p70S6, signal transducers and activators of transcription 5b and 6, glycogen synthase kinase 3a/b and 5' AMP-activated protein kinases 1/2. CONCLUSION: Continuous moderate hyperoxia and cyclic moderate hyperoxia/anoxia-induced endothelial inflammation, apoptosis and necrosis. Given the large surface area of the vascular endothelium, moderately elevated O2 levels may contribute to cardiovascular inflammation and injury. TRIAL REGISTRATION: This in-vitro study was not registered in a database.