Oxygen Tension Research Articles

Current incidence, risk factor and outcome of acute respiratory distress syndrome in Nasser Institute ICU, Cairo, Egypt

Abstract Background Acute respiratory distress syndrome (ARDS) represents the severe end of a spectrum of acute lung injury due to many different insults. It manifests as acute and persistent lung inflammation with increased lung permeability. Aim of the study To assess the current incidence, risk factors and outcome of acute respiratory distress syndrome at Nasser Institute ICU during the period from January 2019 till the end of July 2019. Methodology The study enrolled 50 patients who were admitted to Nasser Institute ICU and met the Berlin criteria for ARDS during the study period. Results The incidence of ARDS was (3.12%), 54% of which were severe, 26% were moderate, and 20% were mild. Mortality rate was 52%, 88.46% of which were severe cases. Severity index was positively correlated with mortality rate (P- value <0.001). Pneumonia with sepsis was the most common risk factor (74%) and had statistically significant positive correlation with mortality (P = 0.017). Conclusion Incidence of ARDS was relatively small at our institute (3.12%), yet, it has a serious and a potentially fatal outcome with high mortality rate (52%). Key words: Acute Respiratory Distress Syndrome, ARDS, ICU, incidence, risk factor, outcome, mortality, Nasser Institute. Abbreviations: ARDS: Acute Respiratory Distress Syndrome. PaO2: Partial pressure of oxygen. FiO2: Fraction of inspired oxygen. PEEP : Positive end expiratory pressure.TV: Tidal volume. ABG: Arterial blood gases. PH: potential hydrogen. PaCO2: partial pressure of carbon dioxide. HCO3: Bicarbonate. SO2: blood oxygen saturation. ICU: intensive care unit.

The Importance of Hypoxia-Related to Hemoglobin Concentration in Breast Cancer.

The importance of hemoglobin (Hgb) as a novel prognostic biomarker in predicting clinical features of cancers has been the subject of intense interest. Anemia is common in various types of cancer including breast cancer (BC) and is considered to be attributed to tumoral hypoxia. Cancer microenvironments are hypoxic compared with normal tissues, and this hypoxia is associated with Hgb concentration. Recent preclinical documents propose a direct or indirect correlation of intratumoral hypoxia, specifically along with acidity, with Hgb concentration and anemia. Analysis of the prognostic value of Hgb in BC patients has demonstrated increased hypoxia in the intratumoral environment. A great number of studies demonstrated that lower concentrations of Hgb before or during common cancer treatments, such as radiation and chemotherapy, is an essential risk factor for poor prognostic and survival, as well as low quality of life in BC patients. This data suggests a potential correlation between anemia and hypoxia in BC. While low Hgb levels are detrimental to BC invasion and survival, identification of a distinct and exact threshold for low Hgb concentration is challenging and inaccurate. The optimal thresholds for Hgb and partial pressure of oxygen (pO2) vary based on different factors including age, gender, therapeutic approaches, and tumor types. While necessitating further investigations, understanding the correlation of Hgb levels with tumoral hypoxia and oxygenation could improve exploring strategies to overcome radio-chemotherapy related anemia in BC patients. This review highlights the collective association of Hgb concentration and hypoxia condition in BC progression.

P-165 Benefits of ultra-low oxygen tension (2%) in patients with low quality embryos or previous arrest: the patient as its own control

Abstract Study question Is reduction in oxygen tension from 5% to 2% after D3 of extended culture beneficial for blastocyst development in patients with previous failed culture? Summary answer Ultra-low oxygen tension in extended culture improves blastocyst development (overall blastulation rate OBR), quality (top blastulation rate TPR) and increases the pregnancy rate (PR). What is known already The practice ESHRE guidelines recommends human embryo culture at low oxygen concentrations (2-8%). Traditionally atmospheric conditions (20% O2) were used but better outcomes were observed at low monophasic 5% O2. Human embryo leaves the oviduct (5-7% O2) to cross the uterus-tubal junction around D3-4 and reaches the uterin ultra-low O2 tension (2%). This decreasing gradient coincides with the shift from pre-compaction oxidative phosphorylation in the oviduct, to post-compaction glycolysis in the uterus. Few studies with ultra-low 2% O2 incubation suggested that the best O2 level may be stage-dependent and its reduction after D3 may be a more physiological approach. Study design, size, duration Prospective observational study in a single private hospital during 2023. 71 patients experienced a failed cycle of extended culture (n = 29 cIVF, n = 37 ICSI and n = 5 Sibling oocytes) with a poor embryo quality and low OBR, under standard monophasic 5% O2 incubation. In the subsequent cycle for these 71 patients (n = 24 cIVF and n = 46 ICSI and n = 1 Sibling oocytes) the O2 level was reduced to 2% from D3 onwards. Participants/materials, setting, methods After a failed extended culture, considered as the control cycle, the patients were enrolled for the study. Blastocysts were rated by Gardner’s classification. In the control cycle embryos were cultured under monophasic 5% O2 until D6. In the subsequent cycle embryos were cultured under 5% O2 until D3 and in ultra-low 2% O2 from D3 to D6. Sage 1-Step™ media was used for both cycles. The statistical analyses were done by chi-square and fisher test. Main results and the role of chance 71 patients were included in the study regardless of age, indication or technique. Each patient was its own control. The mean age was not different between the 2 groups (36.5±4 vs 37.2±4) but the attempt rank was logically statistically higher in the study cycle (2.1±1.4 vs 3.4±1, p<0.001). Oocyte maturity (75% vs 76.4%) and fertilization rate (66.8 vs 70.3%) were similar between groups. The average embryo quality at D3 was poor in both groups. OBR and TBR (40.7% vs 52.4%, p=0.004 and 15.8% vs 37.5%, p<0.001) were statistically higher after culture in ultra-low O2 conditions. Extended culture failure with absence of usable blastocyst (57.7% vs 19.7%, p<0.001) was statistically lower in ultra-low incubation group and the pregnancy rate PR per cycle (3.6% vs 25%, p=0.004) was seven fold higher after ultra-low culture. Limitations, reasons for caution The small size of the sample needs to be expanded in order to confirm the encouraging findings in a larger population. The study will continue during 2024 and will compel the live birth rate and the cumulative live birth rate. Wider implications of the findings Providing embryos with the most physiologic culture system would improve IVF cost-effectiveness and a better infertility management. Embryo energetic adaptation to suboptimal conditions results in impaired viability and lower pregnancy rates. In our study extended culture of low-quality embryos under 2% O2 after D3 yielded better culture and pregnancy outcomes. Trial registration number NA

P-217 Keep calm and carry on: assessing the effect of below-benchmark vitrified/warmed donor oocyte survival rates in subsequent laboratory and clinical key performance indicators

Abstract Study question When we experience below benchmark donor oocyte survival rates, are the laboratory and clinical outcomes of the recipient cycle affected? Summary answer Donor-oocyte cryo-survival rates below the benchmark (95-100%) result in slightly lower laboratory KPIs, equivalent live birth rates (LBR) and lower cumulative LBR (CLBR) per cycle. What is known already The use of vitrified/warmed donor oocytes allows overcoming many logistic challenges, but it is hindered by the loss of oocytes due to degeneration after warming. The 2012 Vienna Consensus established the benchmark rate of oocyte survival at 95-100%, competency level at > 85%. Results of < 85% cryo-survival are considered below competency, <70% can be considered poor, and <50% very poor. Below-benchmark rates of survival may not only limit the number of donor oocytes for the cycle, but they can also translate into lower per-oocyte cycle KPIs if the lower survival correlates with lower performance of the surviving oocytes. Study design, size, duration We analyzed 12690 vitrified-warmed donor oocyte recipient cycles, encompassing a total 144793 vitrified/warmed donor oocytes, carried out in a network of European private IVF units from 2018-2022. Cycles with PGT-A and spermatozoa from testicular biopsy were excluded. The primary endpoint of the study was the blastocyst utilization rate per 2PN zygote. Secondary endpoints were fertilization rate, live birth rate after the first single blastocyst transfer (SET-LBR) of each cycle, and cumulative LBR (CLBR). Participants/materials, setting, methods In all cases, fertilization was carried out by ICSI, and embryos were cultured to the blastocyst stage at low oxygen tension. Blastocysts with good or fair quality (A, B & C by ASEBIR Criteria) were considered usable (transferred + cryopreserved blastocyts / zygotes). Differences in proportions were analyzed using chi-square and the adjusted odds ratio (OR) was calculated using multivariable logistic regression. Main results and the role of chance Baseline donor and patient characteristics such as age, stimulation duration and dose, total donor oocytes per cycle, male factor, and fresh/frozen/donor spem were compared between groups and adjusted for when necessary. The mean number of warmed oocytes per cycle was 11.4±3.22 with a mean survival rate of 89.2%. More oocytes per cycle were consumed in the lower survival groups, yet the total oocytes available for ICSI was smaller in the below competency, poor and very poor survival groups. There were differences in the proportion of usable blastocysts per zygote amongst the survival rate groups (benchmark: 48.9%; competence: 47.0%, below-competence: 46.0%; poor: 43.6%; very-poor:43.6%, p < 0.001). Fertilization rates also differed between survival groups (benchmark: 76.9%; competence: 76.5%, below-competence: 75.6%; poor: 74.7%; very-poor:75.4%, p < 0.001) The adjusted odds ratio of live birth on the first SET of the cycle was not lower to the benchmark survival group in all the lower survival groups (Benchmark: 40.9%; Competence: OR:0.995; 95%CI:0.971-1.018; below-competence: OR:0.996; 95%CI:0.970-1.023; poor: OR:1.044; 95%CI:1.003-1.086, and very-poor: OR:1.069; 95%CI:0.976-1.170). The CLBR decreased in lower survival groups, with 80.8% for the benchmark survival group, 80.3% (p = 0.539) for competence, 76.2% (p < 0.001) for below-competence, 72.5% (p < 0.001) for poor, and 74.8% (p = 0.056) for very-poor. Limitations, reasons for caution These results are limited to a donor-oocyte population. Wider implications of the findings Lower oocyte-cryo-survival rates resulted in a lower total number of usable blastocysts obtained for the recipient, and consequently, lower CLBR. However, the competence of surviving oocytes is encouraging, with laboratory KPIs in very close range irrespectively of the cohort survival rates, and similar implantation potential of the obtained blastocysts. Trial registration number not applicable

Oxidation of Cu-Pb-As Ternary Alloys at 960–1080°C with Various Oxygen Partial Pressures and the Distribution Behavior of Arsenic

Oxidation of Cu-Pb-As Ternary Alloys at 960–1080°C with Various Oxygen Partial Pressures and the Distribution Behavior of Arsenic

Effects of substrate availability and mitochondrial disruption on oxidative metabolism and sperm motility in fertile dogs.

In several mammalian species, the measurement of mitochondrial oxygen consumption (MITOX) under different metabolic conditions has demonstrated a positive correlation with sperm motility and may be a sensitive indicator of mitochondrial health. In general, the maintenance of sperm motility and many key sperm functions and fertilizing events are heavily energy-dependent processes, and some species-specific substrate preferences exist. Although canine sperm have been known to undergo capacitation and maintain motility with supplementation of a wide range of energy substrates, the relationship between mitochondrial function, and the maintenance of oxidative metabolism and sperm motility remain unclear. The objective of this study was to explore the metabolic flexibility of canine sperm, and to investigate the relationship between mitochondrial function, and maintenance of motility under differing nutrient conditions. We explored substrate preferences and the bioenergetics underlying maintenance of canine sperm motility by monitoring mitochondrial oxidative function and sperm kinematics in the presence of mitochondrial effector drug treatments: FCCP, antimycin (ANTI), and oligomycin (OLIGO). We hypothesized that canine sperm possess the ability to use compensatory pathways and utilize diverse nutrient sources in the maintenance of motility. Oxygen consumption (change in pO2, oxygen partial pressure) and sperm kinematics (CASA) were measured concurrently (t0-t30) to assess the relationship between oxidative metabolism and maintenance of sperm motility in dogs. Four media were tested: containing glucose, lactate, and pyruvate (GLP), containing glucose (G), fructose (F), or lactate and pyruvate (LP). In the absence of pharmacological inhibition of the electron transport chain, energetic substrate had no effect on sperm kinematics in fertile dogs. Following mitochondrial disruption by ANTI and OLIGO, mitochondrial oxygen consumption was negatively correlated with several sperm motility parameters in GLP, G, F, and LP media. In every media, FCCP treatment quickly induced significantly higher oxygen consumption than in untreated sperm, and spare respiratory capacity, the maximal inducible oxidative metabolism, was high. With respiratory control ratios RCR >1 there was no indication of bioenergetic dysfunction in any media type, indicating that sperm mitochondria of fertile dogs have a high capacity for substrate oxidation and ATP turnover regardless of substrate. Our results suggest MITOX assessment is a valuable tool for assessing mitochondrial functionality, and that canine sperm employ flexible energy management systems which may be exploited to improve sperm handling and storage.

Spectral characterization of a Cryo-Cooled CO laser operating with CO2 laser gas mixture

This study explores the emission spectra and performance characteristics of a cryo-cooled CO laser system operating with CO2 laser gas mixture under various operating conditions, viz., N2 free gas mixture, different coolant temperatures and in grating tuned configuration. The narrow operational window in case of N2 free gas mixture, increased output power and richer emission spectrum obtained with the addition of N2 gas indicates enhanced discharge stability and efficient excitation in presence of Nitrogen. The emission spectrum revealed shifting of the trapping levels towards lower vibrational quantum number with reducing coolant temperature and the same was also corroborated by theoretical calculations. No lasing was observed for vibrational levels V>15 which is attributed to the higher partial pressure of oxygen inherently present in the gain medium formed due to dissociation of CO2. The system lased on more than 20 transitions in grating tuned configuration with power exceeding 100mW on several lines. The presence of higher concentration of O2 in the discharge prevents carbon deposition − a common issue in CO lasers. This study underscores the significance of this unconventional CO laser system offering reliable operation in the 5 µm wavelength region without the usage of extraneous CO gas.

A case of self-limiting respiratory distress in a postpartum mother – transfusion related acute lung injury

A 37-year-old woman, treated for postpartum haemorrhage, developed sudden-onset acute respiratory distress characterised by tachypnoea, desaturation and widespread crepitations, on the first day postpartum. She had low partial pressure of oxygen to the fractional inspired oxygen concentration (PaO2/FiO2) ratio and bilateral patchy opacities in chest radiograph. Despite having a high oxygen requirement, her clinical and radiographic abnormalities spontaneously resolved in 30 hours, after a conservative treatment approach. This case report delves into the rare, yet serious entity of transfusion-related acute lung injury (TRALI) and underscores the importance of considering it among other potential causes of shortness of breath following blood transfusion in postpartum patients.

An unconventional approach for the efficient recovery of iron, cobalt, copper and silicon from copper slag

High-grade heavy metal elements in copper slag (CS) are worth recovering. Unfortunately, the high viscosity of leaching solution, low leaching efficiency, difficult filtration and low separation efficiency of valuable components exist in the traditional sulfuric acid leaching process. In this study, the above problems are solved by sulfuric acid pretreatment + curing + water leaching. Moreover, iron, cobalt and copper ions in solution are separated by stepwise precipitation. The final iron, cobalt, copper and silicon recoveries are 99.01 %, 98.45 %, 93.13 % and 99.52 %, respectively. Thermodynamic calculations show that H4SiO4 can be converted to insoluble SiO2 to improve filtration properties under curing conditions of sulfur dioxide partial pressures of 10−20∼0 atm, oxygen partial pressures of 10−20∼0 atm and 400–600k. Simulation studies of the phase equilibria of the components of the leach solution by Visual MINTEQ showed that the oxidation of Fe2+ to Fe3+ is necessary for the removal of Fe2+ from the solution by precipitation. This study provides a new idea for the efficient utilization of CS.

Effects of H2 on Microstructures of Cr2O3 Scales Grown in Water Vapour and Consequences for Breakaway

Model alloy, Fe-20Cr (wt.%), was exposed in Ar-(5, 20)H2O, Ar-(5, 20)H2O-5H2 and Ar-20O2 (vol.%) at 750 and 850oC. The alloy formed Cr2O3 scales plus Fe-rich oxide nodules in H2O-containing gases, but a Cr2O3 scale in Ar-20O2 at 750oC. The alloy formed an outer (Cr,Fe)-rich oxide layer and an inner, porous Cr2O3 layer in Ar-5H2O-5H2, whereas a dense Cr2O3 scale grew in Ar-5H2O at 850oC. Application of Wagner’s theory successfully differentiated effects of oxide grain sizes and oxygen partial pressures of gases on scaling rates. Chemically inert SiO2 markers showed that Cr2O3 scales grew by outward metal diffusion.

Effects of H2 on microstructures of Cr2O3 scales grown in water vapour and consequences for breakaway

Model alloy, Fe-20Cr (wt%), was exposed in Ar-(5, 20)H2O, Ar-(5, 20)H2O-5H2 and Ar-20O2 (vol%) at 750 and 850 °C. The alloy formed Cr2O3 scales plus Fe-rich oxide nodules in H2O-containing gases, but a Cr2O3 scale in Ar-20O2 at 750 °C. The alloy formed an outer (Cr,Fe)-rich oxide layer and an inner, porous Cr2O3 layer in Ar-5H2O-5H2, whereas a dense Cr2O3 scale grew in Ar-5H2O at 850 °C. Application of Wagner’s theory successfully differentiated effects of oxide grain sizes and oxygen partial pressures of gases on scaling rates. Chemically inert SiO2 markers showed that Cr2O3 scales grew by outward metal diffusion.

Correlation between Thermodynamic Studies and Experimental Process for Roasting Cobalt-Bearing Pyrite

Cobalt is a critical metal widely distributed in nature, but cobalt ore has hardly been found as an independent mineral. Cobalt-bearing pyrite tailings separated from iron ore is one of the resources for recovering cobalt. In the following study, roasting is carried out to oxidize cobalt-bearing pyrite tailings for preparing and recovering the cobalt by acid leaching. The further aim of the research is to determine and control the optimal technological regime for roasting by using thermodynamic modeling. The phase transition in Fe–S–O and Co–S–O systems and its mechanism are analyzed under the partial pressure of oxygen and sulfur dioxide at constant temperatures. Thermodynamic modeling proves that iron and cobalt sulfides can be intensively oxidized at a relatively high temperature (>900 °C) under an atmosphere of logp(O2) > −5, leading to the formation of SO2 (logp(SO2) < 0). The results of the roasting experiment indicate 98% desulfurization degree upon holding for about 4–5 h and at > 1000 °C. Based on these thermodynamic modeling and experimental results, the roasting of cobalt containing pyrite can be optimized with substantial productivity with regard to the metal oxide and cobalt thereof. Oxidative roasting also allows the elimination of environmentally hazardous gases such as sulfur during the process.

Associations between TLRs 2 and 4, and β-lactam antibiotics in COPD patients complicated with pulmonary infections.

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the world. We aimed to investigate the associations between toll-like receptors 2 and 4 (TLR-2 and TLR-4) and β-lactam antibiotics in COPD patients complicated with pulmonary infections. A total of 156 COPD patients complicated with pulmonary infections were included. Their blood gas, airway resistance, health status, expression levels of TLR-2 and TLR-4, and pulmonary function were analyzed after treatment with β-lactam antibiotics. Blood gas indices oxygen saturation, partial pressure of oxygen, and partial pressure of carbon dioxide at one day before treatment, on the fifteenth day of treatment, and on the first day after the end of treatment showed significant differences (p < 0.01). Significant differences were also detected in airway resistance indices (p < 0.01). The differences in the mRNA expression levels of TLR-2 and TLR-4 were significant (p < 0.05). Downward trends were observed in the clinical pulmonary infection score and acute physiology and chronic health evaluation II score, which indicated alleviation of the disease. Pulmonary function indices recorded vital capacity (VC)/predicted VC (%), recorded forced vital capacity at 1 s (FEV1)/predicted FEV1 (%), and residual volume/total lung capacity were significantly different (p < 0.05). β-Lactam antibiotics had obvious therapeutic effects on COPD patients complicated with pulmonary infections, probably by suppressing or attenuating TLR-2- and TLR-4-mediated inflammatory responses. It is necessary to comprehensively evaluate and choose appropriate antibiotics, aiming for maximum relief of the pain to help patients recover quickly.

Predicting the development of delayed cerebral ischemia in patients with ruptured arterial aneurysms

Introduction. Vasospasm and delayed cerebral ischemia (DCI), which develop after rupture of cerebral arterial aneurysms and their surgical treatment, are serious complications that worsen the clinical outcome of the disease. The ability to predict the risk of developing these complications is an urgent task allowing to reduce neurological deficits and improve the quality of the patients’ life after aneurysm rupture. Aim – to develop a prognostic model for the development of DCI in patients with ruptured cerebral arterial aneurysms based on the study of a complex of clinical manifestations and a number of laboratory parameters. Material and methods. We examined 91 patients with ruptured arterial aneurysms and the development of subarachnoid hemorrhage in the acute period, identifying the main group with the development of DCI (n=67) and the comparison group without DCI (n=24) in the pre- and postoperative periods. Clinical neurological and neuroimaging studies have been carried out. We studied indicators of blood oxygen transport function, platelet aggregation, coagulogram, concentration of nitrates/nitrites (NOx), angiotensin-converting enzyme (ACE) in venous blood in the pre- and postoperative periods. Results. Based on the logistic regression equation, we determined that predictors influencing the probability of DCI development after aneurysm rupture and clipping include a score on the Glasgow Coma Scale (p=0.001), the p50 value is the partial pressure of oxygen in the blood at which hemoglobin is oxygen saturated by 50% (p=0.001), ACE concentration (p=0.013), NOx/ACE index (p=0.001) and the degree of platelet aggregation according to Traptest (p=0.005). The threshold value of the result of the logistic regression equation was 0.58 with a diagnostic sensitivity of 85.4% and specificity of 69.3%, the area under the ROC of the AUC curve was 0.88±0.015 (p&lt;0.001), which indicates the high quality of the constructed model. Conclusion. The developed predictive model of the probability of DCI development in patients with ruptured arterial cerebral aneurysms with a diagnostic efficiency of 88% allows timely identifying patients for whom it is advisable to begin neuroprotective therapy before surgical treatment.

Lung ultrasound score evaluation of the effect of pressure-controlled ventilation volume-guaranteed on patients undergoing laparoscopic-assisted radical gastrectomy.

Laparoscopic-assisted radical gastrectomy (LARG) is the standard treatment for early-stage gastric carcinoma (GC). However, the negative impact of this procedure on respiratory function requires the optimized intraoperative management of patients in terms of ventilation. To investigate the influence of pressure-controlled ventilation volume-guaranteed (PCV-VG) and volume-controlled ventilation (VCV) on blood gas analysis and pulmonary ventilation in patients undergoing LARG for GC based on the lung ultrasound score (LUS). The study included 103 patients with GC undergoing LARG from May 2020 to May 2023, with 52 cases undergoing PCV-VG (research group) and 51 cases undergoing VCV (control group). LUS were recorded at the time of entering the operating room (T0), 20 minutes after anesthesia with endotracheal intubation (T1), 30 minutes after artificial pneumoperitoneum (PP) establishment (T2), and 15 minutes after endotracheal tube removal (T5). For blood gas analysis, arterial partial pressure of oxygen (PaO2) and partial pressure of carbon dioxide (PaCO2) were observed. Peak airway pressure (Ppeak), plateau pressure (Pplat), mean airway pressure (Pmean), and dynamic pulmonary compliance (Cdyn) were recorded at T1 and T2, 1 hour after PP establishment (T3), and at the end of the operation (T4). Postoperative pulmonary complications (PPCs) were recorded. Pre- and postoperative serum interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunosorbent assay. Compared with those at T0, the whole, anterior, lateral, posterior, upper, lower, left, and right lung LUS of the research group were significantly reduced at T1, T2, and T5; in the control group, the LUS of the whole and partial lung regions (posterior, lower, and right lung) decreased significantly at T2, while at T5, the LUS of the whole and some regions (lateral, lower, and left lung) increased significantly. In comparison with the control group, the whole and regional LUS of the research group were reduced at T1, T2, and T5, with an increase in PaO2, decrease in PaCO2, reduction in Ppeak at T1 to T4, increase in Pmean and Cdyn, and decrease in Pplat at T4, all significant. The research group showed a significantly lower incidence of PPCs than the control group within 3 days postoperatively. Postoperative IL-1β, IL-6, and TNF-α significantly increased in both groups, with even higher levels in the control group. LUS can indicate intraoperative non-uniformity and postural changes in pulmonary ventilation under PCV-VG and VCV. Under the lung protective ventilation strategy, the PCV-VG mode more significantly improved intraoperative lung ventilation in patients undergoing LARG for GC and reduced lung injury-related cytokine production, thereby alleviating lung injury.

Analysis of the Oxidation Behavior and Formation of an Extremely Thin Oxide Layer with a Novel Hot-Stamped Steel

This study investigates enhancing the high-temperature oxidation resistance of hot-stamped steels by adding the Cr/Mn/Si elements to form an extremely thin oxide layer. Under low oxygen partial pressure conditions and high Cr content in the matrix, the oxide layer of a 38Cr3MnNbVMo hot-rolled plate containing the Mo element and high Si content was further thinned to 0.6 μm after cooling at 900 °C for 5 min. The structure of the ultra-thin oxide layer consists of Fe3O4, Mn oxides, FeCr2O4, Cr2O3, and Fe2SiO4 oxides. Compared to other antioxidant elements, under low oxygen partial pressure conditions, Si is more prone to oxidation, forming ultra-thin (22 nm) Fe2SiO4 oxides at the matrix interface. Combined with Cr2O3, FeCr2O4, and Mn oxides, it collectively inhibits the mutual diffusion of external O ions and matrix Fe ions. Furthermore, the addition of the Mo element improves the oxidation resistance. The synergistic effect of multiple powerful oxidation-resistant elements and oxide products effectively inhibits the growth of the iron oxide scale, enhancing the oxidation resistance of hot-rolled, hot-stamped steel.

Pancreas Preservation: Hypothermic Oxygenated Perfusion to Improve Graft Reperfusion.

The clinical standard for pancreas preservation for transplantation is static cold storage (SCS). Oxygenation during preservation has been shown to be advantageous in clinical studies. This study evaluates the efficiency of different oxygenation modalities during hypothermic pancreas preservation. Thirty-two porcine pancreases were procured in a controlled donation after circulatory death model and were divided to be preserved in 8 groups: (1) SCS, (2) hypothermic machine perfusion (HMP), (3) hypothermic oxygenated machine perfusion (HOPE) with 21% oxygen, (4) HOPE and 100%, (5) SCS and oxygen carrier, M101, (6) HMP and M101, (7) HOPE 21% and M101, and (8) HOPE 100% and M101. All the groups underwent 24 h of hypothermic preservation, followed by 2 h of normothermic reperfusion. Oxygen partial pressures were assessed using parenchymal probes. Perfusion parameters, perfusate samples, and tissue biopsies were analyzed. This study showed that HMP was linked to higher tissue oxygen partial pressures, lower succinate levels, and better reperfusion parameters. Furthermore, the addition of M101 to either SCS or HMP was associated with lower succinate and creatinine phosphokinase accumulation, suggesting a protective effect against ischemia. Our research has demonstrated the efficacy of machine perfusion in hypothermic conditions in providing oxygen to the pancreas during preservation and conditioning the pancreatic microvasculature for reperfusion during transplantation. Furthermore, the addition of M101 suggests a protective effect on the graft from ischemia.

Ras-dependent activation of BMAL2 regulates hypoxic metabolism in pancreatic cancer.

To identify drivers of malignancy in human pancreatic ductal adenocarcinoma (PDAC), we performed regulatory network analysis on a large collection of expression profiles from laser capture microdissected samples of PDAC and benign precursors. We discovered that BMAL2 plays a role in the initiation, progression, post resection survival, and KRAS activity in PDAC. Functional analysis of BMAL2 target genes led us to hypothesize that it plays a role in regulating the response to hypoxia, a critical but poorly understood feature of PDAC physiology. Knockout of BMAL2 in multiple human PDAC cell lines revealed effects on viability and invasion, particularly under hypoxic conditions. Loss of BMAL2 also affected glycolysis and other metabolic processes. We found that BMAL2 directly regulates hypoxia-responsive target genes. We also found that BMAL2 is necessary for the stabilization of HIF1A upon exposure to hypoxia, but destabilizes HIF2A under hypoxia. These data demonstrate that BMAL2 is a master transcriptional regulator of hypoxia responses in PDAC and may serve as a long-sought molecular switch that distinguishes HIF1A- and HIF2A-dependent modes of hypoxic metabolism.

Carbon Dioxide Targets in Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome.

Target values for arterial carbon dioxide tension (PaCO2) in extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS) are unknown. We hypothesized that lower PaCO2 values on ECMO would be associated with lighter sedation. We used data from two independent patient cohorts with ARDS spending 1,177 days (discovery cohort, 69 patients) and 516 days (validation cohort, 70 patients) on ECMO and evaluated the associations between daily PaCO2, pH, and bicarbonate (HCO3) with sedation. Median PaCO2 was 41 (interquartile range [IQR] = 37-46) mm Hg and 41 (IQR = 37-45) mm Hg in the discovery and the validation cohort, respectively. Lower PaCO2 and higher pH but not bicarbonate (HCO3) served as significant predictors for reaching a Richmond Agitation Sedation Scale (RASS) target range of -2 to +1 (lightly sedated to restless). After multivariable adjustment for mortality, tracheostomy, prone positioning, vasoactive inotropic score, Simplified Acute Physiology Score (SAPS) II or Sequential Organ Failure Assessment (SOFA) Score and day on ECMO, only PaCO2 remained significantly associated with the RASS target range (adjusted odds ratio 1.1 [95% confidence interval (CI) = 1.01-1.21], p = 0.032 and 1.29 [95% CI = 1.1-1.51], p = 0.001 per mm Hg decrease in PaCO2 for the discovery and the validation cohort, respectively). A PaCO2 ≤40 mm Hg, as determined by the concordance probability method, was associated with a significantly increased probability of a sedation level within the RASS target range in both patient cohorts (adjusted odds ratio = 2.92 [95% CI = 1.17-7.24], p = 0.021 and 6.82 [95% CI = 1.50-31.0], p = 0.013 for the discovery and the validation cohort, respectively).

The Effects of Head Elevation on Intracranial Pressure, Cerebral Perfusion Pressure, and Cerebral Oxygenation Among Patients with Acute Brain Injury: A Systematic Review and Meta-Analysis.

Head elevation is recommended as a tier zero measure to decrease high intracranial pressure (ICP) in neurocritical patients. However, its quantitative effects on cerebral perfusion pressure (CPP), jugular bulb oxygen saturation (SjvO2), brain tissue partial pressure of oxygen (PbtO2), and arteriovenous difference of oxygen (AVDO2) are uncertain. Our objective was to evaluate the effects of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2 among patients with acute brain injury. We conducted a systematic review and meta-analysis on PubMed, Scopus, and Cochrane Library of studies comparing the effects of different degrees of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2. A total of 25 articles were included in the systematic review. Of these, 16 provided quantitative data regarding outcomes of interest and underwent meta-analyses. The mean ICP of patients with acute brain injury was lower in group with 30° of head elevation than in the supine position group (mean difference [MD] - 5.58mm Hg; 95% confidence interval [CI] - 6.74 to - 4.41mm Hg; p < 0.00001). The only comparison in which a greater degree of head elevation did not significantly reduce the ICP was 45° vs. 30°. The mean CPP remained similar between 30° of head elevation and supine position (MD - 2.48mm Hg; 95% CI - 5.69 to 0.73mm Hg; p = 0.13). Similar findings were observed in all other comparisons. The mean SjvO2 was similar between the 30° of head elevation and supine position groups (MD 0.32%; 95% CI - 1.67% to 2.32%; p = 0.75), as was the mean PbtO2 (MD - 1.50mm Hg; 95% CI - 4.62 to 1.62mm Hg; p = 0.36), and the mean AVDO2 (MD 0.06µmol/L; 95% CI - 0.20 to 0.32µmol/L; p = 0.65).The mean ICP of patients with traumatic brain injury was also lower with 30° of head elevation when compared to the supine position. There was no difference in the mean values of mean arterial pressure, CPP, SjvO2, and PbtO2 between these groups. Increasing degrees of head elevation were associated, in general, with a lower ICP, whereas CPP and brain oxygenation parameters remained unchanged. The severe traumatic brain injury subanalysis found similar results.