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Carbon Dioxide Changes during High-flow Nasal Oxygenation in Apneic Patients: A Single-center Randomized Controlled Noninferiority Trial.
Riva, T, Greif, R, Kaiser, H, Riedel, T, Huber, M, Theiler, L, Nabecker, S
Anesthesiology. 2022;(1):82-92
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Abstract
BACKGROUND Anesthesia studies using high-flow, humidified, heated oxygen delivered via nasal cannulas at flow rates of more than 50 l · min-1 postulated a ventilatory effect because carbon dioxide increased at lower levels as reported earlier. This study investigated the increase of arterial partial pressure of carbon dioxide between different flow rates of 100% oxygen in elective anesthetized and paralyzed surgical adults before intubation. METHODS After preoxygenation and standardized anesthesia induction with nondepolarizing neuromuscular blockade, all patients received 100% oxygen (via high-flow nasal oxygenation system or circuit of the anesthesia machine), and continuous jaw thrust/laryngoscopy was applied throughout the 15-min period. In this single-center noninferiority trial, 25 patients each, were randomized to five groups: (1) minimal flow: 0.25 l · min-1, endotracheal tube; (2) low flow: 2 l · min-1, continuous jaw thrust; (3) medium flow: 10 l · min-1, continuous jaw thrust; (4) high flow: 70 l · min-1, continuous jaw thrust; and (5) control: 70 l · min-1, continuous laryngoscopy. Immediately after anesthesia induction, the 15-min apnea period started with oxygen delivered according to the randomized flow rate. Serial arterial blood gas analyses were drawn every 2 min. The study was terminated if either oxygen saturation measured by pulse oximetry was less than 92%, transcutaneous carbon dioxide was greater than 100 mmHg, pH was less than 7.1, potassium level was greater than 6 mmol · l-1, or apnea time was 15 min. The primary outcome was the linear rate of mean increase of arterial carbon dioxide during the 15-min apnea period computed from linear regressions. RESULTS In total, 125 patients completed the study. Noninferiority with a predefined noninferiority margin of 0.3 mmHg · min-1 could be declared for all treatments with the following mean and 95% CI for the mean differences in the linear rate of arterial partial pressure of carbon dioxide with associated P values regarding noninferiority: high flow versus control, -0.0 mmHg · min-1 (-0.3, 0.3 mmHg · min-1, P = 0.030); medium flow versus control, -0.1 mmHg · min-1 (-0.4, 0.2 mmHg · min-1, P = 0.002); low flow versus control, -0.1 mmHg · min-1 (-0.4, 0.2 mmHg · min-1, P = 0.003); and minimal flow versus control, -0.1 mmHg · min-1 (-0.4, 0.2 mmHg · min-1, P = 0.004). CONCLUSIONS Widely differing flow rates of humidified 100% oxygen during apnea resulted in comparable increases of arterial partial pressure of carbon dioxide, which does not support an additional ventilatory effect of high-flow nasal oxygenation.
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Metal (Mo, W, Ti) Carbide Catalysts: Synthesis and Application as Alternative Catalysts for Dry Reforming of Hydrocarbons-A Review.
Czaplicka, N, Rogala, A, Wysocka, I
International journal of molecular sciences. 2021;(22)
Abstract
Dry reforming of hydrocarbons (DRH) is a pro-environmental method for syngas production. It owes its pro-environmental character to the use of carbon dioxide, which is one of the main greenhouse gases. Currently used nickel catalysts on oxide supports suffer from rapid deactivation due to sintering of active metal particles or the deposition of carbon deposits blocking the flow of gases through the reaction tube. In this view, new alternative catalysts are highly sought after. Transition metal carbides (TMCs) can potentially replace traditional nickel catalysts due to their stability and activity in DR processes. The catalytic activity of carbides results from the synthesis-dependent structural properties of carbides. In this respect, this review presents the most important methods of titanium, molybdenum, and tungsten carbide synthesis and the influence of their properties on activity in catalyzing the reaction of methane with carbon dioxide.
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Long-Term Outcomes of Radical Radiation Therapy with Hypoxia Modification with Biomarker Discovery for Stratification: 10-Year Update of the BCON (Bladder Carbogen Nicotinamide) Phase 3 Randomized Trial (ISRCTN45938399).
Song, YP, Mistry, H, Irlam, J, Valentine, H, Yang, L, Lane, B, West, C, Choudhury, A, Hoskin, PJ
International journal of radiation oncology, biology, physics. 2021;(5):1407-1415
Abstract
PURPOSE Many muscle-invasive bladder cancers are hypoxic, which limits the efficacy of radiation therapy. Hypoxia modification using carbogen and nicotinamide has been tested in a phase 3 trial, Bladder Carbogen Nicotinamide. We present mature follow-up data with biomarker predictions of outcomes. METHODS AND MATERIALS Bladder Carbogen Nicotinamide is a prospective, phase 3, multicenter, randomized, 2-arm, nonblinded clinical trial. Participants were randomized to receive radical radiation therapy (RT; control arm) alone or with the addition of carbogen (98% O2; 2% CO2) and nicotinamide (CON). Patients with muscle-invasive or high-grade non-muscle invasive bladder cancer were included. Tumor tissue was collected at entry and was analyzed for tumor necrosis, hypoxia (24-gene signature), and basal and luminal tumor molecular subtypes. Overall survival (OS) and disease-free survival and relationships with biomarker status outcomes are analyzed using multivariable Cox regression and log-rank analysis. RESULTS We analyzed 333 patients with a median follow-up of 10.3 years. The 10-year OS rates were 30% (95% confidence interval [CI], 0.23-0.39) in RT + CON patients and 24% (95% CI, 0.18-0.33) in the RT-alone patients (hazard ratio [HR], 0.80; 95% CI, 0.61-1.04; P = .08). The greatest benefit from CON was seen in patients with tumor necrosis (n = 79; 5-year OS, 53% vs. 33% in patients without tumor necrosis; HR, 0.59; 95% CI, 0.36-0.99; P = .04). Cases with a high hypoxia gene score (n = 75) had a 5-year OS rate of 51%, compared to 34% for a low score (HR, 0.64; 95% CI, 0.38-1.08; P = .09); those with the basal molecular subtype (n = 70) had a 5-year OS rate of 58%, compared to 38% for those with the luminal subtype (HR, 0.58; 95% CI, 0.32-1.06; P = .08). CONCLUSIONS Although the improvement in long-term OS in the whole population is not statistically significant, patients selected by necrosis and high hypoxia gene score benefitted from hypoxia modification.
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Effect of sodium-chloride ion difference on pH regulation.
Nozawa, H, Tsuboi, N, Nariai, R, Nishimura, N, Nakagawa, S
Clinical biochemistry. 2021;:75-77
Abstract
BACKGROUND In the Stewart approach, the difference between the cation and anion concentrations, especially between sodium, accounting for the majority of cations, and chloride, comprising the majority of anions, is an important factor in pH regulation. This study investigated the effect of sodium-chloride ion difference (SCD) on pH regulation comparing with those of PaCO2 and lactate. METHODS Arterial blood gas samples measured at our pediatric intensive care unit of a tertiary children's hospital between January and June 2020 were included. Samples that met the following criteria were excluded: samples collected from patients taking potassium bromide and samples with lactate concentration of >25 mmol/L. From the eligible data, pH was chosen as the dependent variable and SCD, lactate, and PaCO2 as independent variables, and then, a multiple regression analysis was performed. RESULTS In total, 5360 samples were included. Of these, five samples were excluded according to the exclusion criteria. Finally, 5355 samples were analyzed. As the variance inflation factors were <2.0 for all three variables, there was no multicollinearity. The following model was derived: pH = 7.384 + [0.97 × SCD (mEq/L) - 0.66 × PaCO2 (mmHg) - 1.33 × Lac (mmol/L)] × 10-2 (adjusted R-squared = 0.73; P value < 0.001). Based on the standardized partial regression coefficients (β), pH was affected in the order of PaCO2 (βPaCO2 = -0.95), SCD (βSCD = 0.72), and lactate (βlactate = -0.33). CONCLUSIONS The prevention of SCD reduction, together with respiratory and metabolic management, is important for pH regulation.
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Novel technologies for emission reduction complement conservation agriculture to achieve negative emissions from row-crop production.
Northrup, DL, Basso, B, Wang, MQ, Morgan, CLS, Benfey, PN
Proceedings of the National Academy of Sciences of the United States of America. 2021;(28)
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Abstract
Plants remove carbon dioxide from the atmosphere through photosynthesis. Because agriculture's productivity is based on this process, a combination of technologies to reduce emissions and enhance soil carbon storage can allow this sector to achieve net negative emissions while maintaining high productivity. Unfortunately, current row-crop agricultural practice generates about 5% of greenhouse gas emissions in the United States and European Union. To reduce these emissions, significant effort has been focused on changing farm management practices to maximize soil carbon. In contrast, the potential to reduce emissions has largely been neglected. Through a combination of innovations in digital agriculture, crop and microbial genetics, and electrification, we estimate that a 71% (1,744 kg CO2e/ha) reduction in greenhouse gas emissions from row crop agriculture is possible within the next 15 y. Importantly, emission reduction can lower the barrier to broad adoption by proceeding through multiple stages with meaningful improvements that gradually facilitate the transition to net negative practices. Emerging voluntary and regulatory ecosystems services markets will incentivize progress along this transition pathway and guide public and private investments toward technology development. In the difficult quest for net negative emissions, all tools, including emission reduction and soil carbon storage, must be developed to allow agriculture to maintain its critical societal function of provisioning society while, at the same time, generating environmental benefits.
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Synthetic Enzyme-Catalyzed CO2 Fixation Reactions.
Aleku, GA, Roberts, GW, Titchiner, GR, Leys, D
ChemSusChem. 2021;(8):1781-1804
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Abstract
In recent years, (de)carboxylases that catalyze reversible (de)carboxylation have been targeted for application as carboxylation catalysts. This has led to the development of proof-of-concept (bio)synthetic CO2 fixation routes for chemical production. However, further progress towards industrial application has been hampered by the thermodynamic constraint that accompanies fixing CO2 to organic molecules. In this Review, biocatalytic carboxylation methods are discussed with emphases on the diverse strategies devised to alleviate the inherent thermodynamic constraints and their application in synthetic CO2 -fixation cascades.
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The association of acute hypercarbia and plasma potassium concentration during laparoscopic surgery: a retrospective observational study.
Weinberg, L, Lee, DK, Gan, C, Ianno, D, Ho, A, Fletcher, L, Banyasz, D, Tosif, S, Jones, D, Bellomo, R, et al
BMC surgery. 2021;(1):31
Abstract
BACKGROUND It is uncertain whether increases in PaCO2 during surgery lead to an increase in plasma potassium concentration and, if so, by how much. Hyperkalaemia may result in cardiac arrhythmias, muscle weakness or paralysis. The key objectives were to determine whether increases in PaCO2 during laparoscopic surgery induce increases in plasma potassium concentrations and, if so, to determine the magnitude of such changes. METHODS A retrospective observational study of adult patients undergoing laparoscopic abdominal surgery was perfomed. The independent association between increases in PaCO2 and changes in plasma potassium concentration was assessed by performing arterial blood gases within 15 min of induction of anaesthesia and within 15 min of completion of surgery. RESULTS 289 patients were studied (mean age of 63.2 years; 176 [60.9%] male, and mean body mass index of 29.3 kg/m2). At the completion of the surgery, PaCO2 had increased by 5.18 mmHg (95% CI 4.27 mmHg to 6.09 mmHg) compared to baseline values (P < 0.001) with an associated increase in potassium concentration of 0.25 mmol/L (95% CI 0.20 mmol/L to 0.31 mmol/L, P < 0.001). On multiple regression analysis, PaCO2 changes significantly predicted immediate changes in plasma potassium concentration and could account for 33.1% of the variance (r2 = 0.331, f(3,259) = 38.915, P < 0.001). For each 10 mmHg increment of PaCO2 the plasma potassium concentration increased by 0.18 mmol/L. CONCLUSION In patients receiving laparoscopic abdominal surgery, there is an increase in PaCO2 at the end of surgery, which is independently associated with an increase in plasma potassium concentration. However, this effect is small and is mostly influenced by intravenous fluid therapy (Plasma-Lyte 148 solution) and the presence of diabetes. Trial registration Retrospectively registered in the Australian New Zealand Clinical Trials Registry (Trial Number: ACTRN12619000716167).
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Supercritical CO2 Extraction as a Tool to Isolate Anti-Inflammatory Sesquiterpene Lactones from Cichorium intybus L. Roots.
Baixinho, JP, Anastácio, JD, Ivasiv, V, Cankar, K, Bosch, D, Menezes, R, de Roode, M, Santos, CND, Matias, AA, Fernández, N
Molecules (Basel, Switzerland). 2021;(9)
Abstract
Cichorium intybus L. or chicory plants are a natural source of health-promoting compounds in the form of supplements such as inulin, as well as other bioactive compounds such as sesquiterpene lactones (SLs). After inulin extraction, chicory roots are considered waste, with most SLs not being harnessed. We developed and optimized a new strategy for SL extraction that can contribute to the conversion of chicory root waste into valuable products to be used in human health-promoting applications. In our work, rich fractions of SLs were recovered from chicory roots using supercritical CO2. A response surface methodology was used to optimize the process parameters (pressure, temperature, flow rate, and co-solvent percentage) for the extraction performance. The best operating conditions were achieved at 350 bar, 40 °C, and 10% EtOH as a co-solvent in a 15 g/min flow rate for 120 min. The extraction with supercritical CO2 revealed to be more selective for the SLs than the conventional solid-liquid extraction with ethyl acetate. In our work, 1.68% mass and a 0.09% sesquiterpenes yield extraction were obtained, including the recovery of two sesquiterpene lactones (8-deoxylactucin and 11β,13-dihydro-8-deoxylactucin), which, to the best of our knowledge, are not commercially available. A mixture of the abovementioned compounds were tested at different concentrations for their toxic profile and anti-inflammatory potential towards a human calcineurin/NFAT orthologue pathway in a yeast model, the calcineurin/Crz1 pathway. The SFE extract obtained, rich in SLs, yielded results of inhibition of 61.74 ± 6.87% with 50 µg/mL, and the purified fraction containing 8-deoxylactucin and 11β,13-dihydro-8-deoxylactucin inhibited the activation of the reporter gene up to 53.38 ± 3.9% at 10 µg/mL. The potential activity of the purified fraction was also validated by the ability to inhibit Crz1 nuclear translocation and accumulation. These results reveal a possible exploitable green technology to recover potential anti-inflammatory compounds from chicory roots waste after inulin extraction.
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The Influence of Environmental Conditions on Secondary Metabolites in Medicinal Plants: A Literature Review.
Pant, P, Pandey, S, Dall'Acqua, S
Chemistry & biodiversity. 2021;(11):e2100345
Abstract
Medicinal plants, a source of different phytochemical compounds, are now subjected to a variety of environmental stresses during their growth and development. Different ecologically limiting factors including temperature, carbon dioxide, lighting, ozone, soil water, soil salinity and soil fertility has significant impact on medicinal plants' physiological and biochemical responses, as well as the secondary metabolic process. Secondary metabolites (SMs) are useful for assessing the quality of therapeutic ingredients and nowadays, these are used as important natural derived drugs such as immune suppressant, antibiotics, anti-diabetic, and anti-cancer. Plants have the ability to synthesize a variety of secondary metabolites to cope with the negative effects of stress. Here, we focus on how individual environmental variables influence the accumulation of plant secondary metabolites. A total of 48 articles were found to be relevant to the review topic during our systematic review. The review showed the influence of different environmental variables on SMs production and accumulation is complex suggesting the relationship are not only species-specific but also related to increases and decline in SMs by up to 50 %. Therefore, this review improves our understanding of plant SMs ability to adapt to key environmental factors. This can aid in the efficient and long-term optimization of cultivation techniques under ambient environmental conditions in order to maximize the quality and quantity of SMs in plants.
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Performance and mechanism of carbon dioxide fixation by a newly isolated chemoautotrophic strain Paracoccus denitrificans PJ-1.
Ye, J, An, N, Chen, H, Ying, Z, Zhang, S, Zhao, J
Chemosphere. 2020;:126473
Abstract
CO2 is regarded as a major contributor to the global warming. CO2 utilization is promising to reduce the CO2 emissions. Currently, the biofixation of CO2 using chemoautotrophs has markedly gain interest in CO2 utilization. In this study, a newly isolated chemoautotroph, Paracoccus denitrificans PJ-1, was used for the biofixation of CO2 under anaerobic condition. Experimental results revealed that Paracoccus denitrificans PJ-1 achieved a high carbon fixation rate (13.25 mg·L-1·h-1) which was ∼10 times faster than the previous reported chemotrophic bacteria using thiosulfate as electron donor. The best CO2 fixation activity of Paracoccus denitrificans PJ-1 was achieved at the pH value of 9.0 and CO2 concentration of 20 vol%. Meanwhile, a high CO2 fixation yield of 106.03 mg·L-1 was reached. The presence of oxygen was adverse to the biofixation, indicating that strain PJ-1 was more suitable for CO2 fixation in anaerobic environments. Carbon mass balance analysis revealed that the carbon from CO2 was mainly fixed into the extracellular organic carbon rather than the biomass. GC-MS analysis and cbbL gene test revealed that Paracoccus denitrificans PJ-1 fixed CO2 through the Calvin-Benson-Bassham cycle and mainly converted CO2 to oxalic acid and succinic acid. Overall, the excellent CO2 fixation capacity of Paracoccus denitrificans PJ-1 suggests that it had potential for CO2 utilization.