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Purpose: Progress toward developing a novel radiocontrast agent for determining pO2 in tumors in a clinical setting is described. The imaging agent is designed for use with electron paramagnetic resonance imaging (EPRI), in which the collision of a paramagnetic probe molecule with molecular oxygen causes a spectroscopic change which can be calibrated to give the real oxygen concentration in the tumor tissue. Procedures: The imaging agent is based on a nanoscaffold of aluminum hydroxide (boehmite) with sizes from 100 to 200 nm, paramagnetic probe molecule, and encapsulation with a gas permeable, thin (10–20 nm) polymer layer to separate the imaging agent and body environment while still allowing O2 to interact with the paramagnetic probe. A specially designed deuterated Finland trityl (dFT) is covalently attached on the surface of the nanoparticle through 1,3-dipolar addition of the alkyne on the dFT with an azide on the surface of the nanoscaffold. This click-chemistry reaction affords 100% efficiency of the trityl attachment as followed by the complete disappearance of the azide peak in the infrared spectrum. The fully encapsulated, dFT-functionalized nanoparticle is referred to as RADI-Sense. Results: Side-by-side in vivo imaging comparisons made in a mouse model made between RADI-Sense and free paramagnetic probe (OX-071) showed oxygen sensitivity is retained and RADI-Sense can create 3D pO2 maps of solid tumors Conclusions: A novel encapsulated nanoparticle EPR imaging agent has been described which could be used in the future to bring EPR imaging for guidance of radiotherapy into clinical reality. [ABSTRACT FROM AUTHOR]

Comparative evaluation of arterial blood gas in patients with stridor, before and after emergency tracheostomy. The present prospective study was conducted in tertiary care Centre from February 2022 to June 2023 on 42 patients who presented with stridor and underwent emergency tracheostomy in our department. After proper history taking and clinical examination, nonsurgical cause of stridor was ruled out. Patients were then classified on the basis of location of cause of stridor (whether oropharyngeal, hypo-pharyngeal, supra-glottic, glottic or sub-glottic). Immediately an arterial blood gas (ABG) analysis was done, and emergency tracheostomy was performed. Following tracheostomy, ABG analysis was done immediately, after 12 h and after 24 h. The mean age of presentation of stridor in our study was 65.02 ± 3.23 years, with male preponderance (Male: female ratio being 3.66:1). Most common etiology of stridor in our study was glottic carcinoma comprising 50%, and least common etiology of stridor was hypopharyngeal carcinoma, and subglottic stenosis comprising 2.4% each. There was statistically significant normalization of ABG in terms of pH, PO2, PCO2, HCO3. Mean pH, PO2, PCO2, and HCO3 before tracheostomy were 7.31, 74.8, 60.6, and 29.8 respectively. Mean pH, PO2, PCO2, HCO3, immediately after tracheostomy were7.38, 91.3, 48.4, and 27.4 respectively. After 12 h of tracheostomy, mean pH, PO2, PCO2, HCO3 were 7.41, 95.4, 42.7, 25.3 respectively. Mean pH, PO2, PCO2, HCO3 24 h after emergency tracheostomy were 7.441, 95.5, 42.8, 24.6 respectively. Emergency tracheostomy in stridor patients improves the acid base and ventilatory status, by relieving the obstruction as evidenced by statistically significant improvement in arterial blood gas values, and can be used as a diagnostic tool in upper airway obstruction. [ABSTRACT FROM AUTHOR]

HBOT increases the proportion of dissolved oxygen in the blood, generating hyperoxia. This increased oxygen diffuses into the mitochondria, which consume the majority of inhaled oxygen and constitute the epicenter of HBOT effects. In this way, the oxygen entering the mitochondria can reverse tissue hypoxia, activating the electron transport chain to generate energy. Furthermore, intermittent HBOT is sensed by the cell as relative hypoxia, inducing cellular responses such as the activation of the HIF-1α pathway, which in turn, activates numerous cellular processes, including angiogenesis and inflammation, among others. These effects are harnessed for the treatment of various pathologies. This review summarizes the evidence indicating that the use of medium-pressure HBOT generates hyperoxia and activates cellular pathways capable of producing the mentioned effects. The possibility of using medium-pressure HBOT as a direct or adjunctive treatment in different pathologies may yield benefits, potentially leading to transformative therapeutic advancements in the future. [ABSTRACT FROM AUTHOR]

CaO solubility in the FeO t -SiO 2 -CaO-Al 2 O 3 -(ZnO, Cr 2 O 3) system has been experimentally investigated at 1200 and 1250 °C under pO 2 of 10−10 atm. Synthetic slags rich in CaO were equilibrated at desired temperatures, followed by water quenching, and analyzed using electron probe X-ray microanalysis (EPMA). In the quaternary FeO t -SiO 2 -CaO-(6 to 10 wt%) Al 2 O 3 system, CaO solubility exhibits a linear increase from 27.5 to 36.9 wt% with decreasing the FeO/SiO 2 (F/S) ratio from 1.66 to 0.62 at 1250 °C. Similarly, at 1200 °C, the CaO solubility increases from 24.9 to 30.8 wt% as the F/S ratio drops from 1.25 to 0.56. Excessive CaO addition to the slags results in the precipitation of melilite phase. Wustite is observed in the F/S ratio range of 1.66 to 1.0, and the size of wustite particles decreases as the F/S ratio decreases. At both 1200 and 1250 °C, the liquid phase with an F/S ratio below 0.42 is in equilibrium with wollastonite (CaSiO 3) in the FeO t -SiO 2 -CaO-Al 2 O 3 system. The addition of a small amount of ZnO (0.4–1.1 wt%) in the slags leads to a slight decrease in CaO solubility by 1–3 wt%, while the presence of 3.3–8.1 wt% of ZnO in the slags results in a decrease of 5–11 wt% in CaO solubility. Similar to the FeO t -SiO 2 -CaO-Al 2 O 3 system, the equilibrated CaO-containing solid phase is also melilite in the FeO t -SiO 2 -CaO-Al 2 O 3 -ZnO system. With the addition of a small amount of Cr 2 O 3 (1.0 wt%) to the FeO t -SiO 2 -CaO-Al 2 O 3 -ZnO system, spinel and dicalcium silicate (Ca 2 SiO 4) precipitate from the liquid slag, and the dissolved CaO concentration in liquid slag increases by 1–3.6 wt% in the F/S ratio range of 1.58 to 0.84, compared to the Cr 2 O 3 -free system. [ABSTRACT FROM AUTHOR]

Mechanical thrombectomy (MT) has become a standard treatment for acute ischemic stroke (AIS) caused by large vessel occlusion (LVO). Recent evidence suggests that general anesthesia (GA) and mechanical ventilation do not lead to inferior neurologic outcomes if compared to non-GA. However, the guidelines lack specific recommendations for ventilation targets during MT under GA. This systematic review aims to identify ventilation strategies correlating with better neurological outcomes in AIS patients undergoing MT, particularly focusing on oxygenation and carbon dioxide (CO2) targets. A systematic search of multiple databases was conducted to identify human studies reporting the correlation between ventilation strategies and neurological outcomes in MT for AIS. Eligible studies included clinical trials, observational studies, and case–control studies. Out of 157 studies assessed, 11 met the inclusion criteria. Five studies investigated oxygenation targets, while six studies explored CO2 targets. The published studies highlighted the controversial role of supplemental normobaric oxygen therapy and its potential association with worse outcomes. Regarding CO2 targets, the studies identified a potential association between end tidal CO2 levels and functional outcomes, with hypocapnia being unfavorable. This systematic review demonstrates that the current available evidence still lacks strength to suggest specific ventilation targets, but it highlights the potential risks of hyperoxia and hypocapnia in this specific cohort of patients. [ABSTRACT FROM AUTHOR]

HBOT increases the proportion of dissolved oxygen in the blood, generating hyperoxia. This increased oxygen diffuses into the mitochondria, which consume the majority of inhaled oxygen and constitute the epicenter of HBOT effects. In this way, the oxygen entering the mitochondria can reverse tissue hypoxia, activating the electron transport chain to generate energy. Furthermore, intermittent HBOT is sensed by the cell as relative hypoxia, inducing cellular responses such as the activation of the HIF-1α pathway, which in turn, activates numerous cellular processes, including angiogenesis and inflammation, among others. These effects are harnessed for the treatment of various pathologies. This review summarizes the evidence indicating that the use of medium-pressure HBOT generates hyperoxia and activates cellular pathways capable of producing the mentioned effects. The possibility of using medium-pressure HBOT as a direct or adjunctive treatment in different pathologies may yield benefits, potentially leading to transformative therapeutic advancements in the future.

Female-biased mortality has been consistently reported in Pacific salmon during their adult upriver migration. We collected coho salmon (Oncorhynchus kisutch (Walbaum, 1792)) upon arrival at their spawning grounds to test whether females are more prone to cardiac oxygen limitations following exercise stress. We used a surgical approach to periodically sample arterial and venous blood over 48 h following recovery from a chase protocol to induce maximum metabolic rate. We found no significant differences in arterial or venous partial pressures of O2 between males and females. Female salmon had significantly elevated plasma cortisol levels but there were no effects of sex on either plasma lactate or K+. Our data show that female coho salmon do not suffer oxygen limitations to the spongy myocardium after a single exercise event at moderate temperatures (14 °C)—at least not when arriving to their spawning grounds. This study found no clear support for a cardiac oxygen limitation underlying elevated female mortality in Pacific salmon. Neither, however, does our study design nor specific findings allow us to rule out cardiac limitations in these fish. Future work should address whether potential oxygen limitations to the spongy myocardium at high temperatures or oxygen limitations to the compact myocardium via coronary blood flow contribute to female-biased mortality earlier on the migratory route. [ABSTRACT FROM AUTHOR]

Blood gas analyzers employing glucose-oxidase biosensors under-recover glucose when p O 2 is low. The manufacturer of the GEM ®Premier™ series of analyzers introduced an algorithm to detect specimens at risk of low p O 2 interference. We investigated the reliability of this algorithm. Whole blood specimens were tested by GEM ®Premier™ 4000 (GEM 4000) and 5000 (GEM 5000). Specimens with an incalculable ("incalc") error code for glucose result or that had a glucose ≥ 20 mmol/L were retested on a second analyzer of the same type within 5 min over the course of 30 months in 5 hospitals in Calgary, Alberta. Discordant retests were defined as either: 1) paired numeric results with a difference >10 %, or 2) an "incalc" code that yielded a numeric result upon retesting. Glucose recovery in relation to p O 2 level was assessed by comparing specimens experimentally depleted of p O 2 between GEM 5000 and a laboratory analyzer (Siemens Vista®). Of 1,776 glucose tests repeated on the GEM 5000 or 1,544 on GEM 4000, 10% were discordant. GEM 5000 produced twice as many discordant numeric retests versus the GEM 4000 [5.9% (98/1,651) vs 2.7% (38/1,391)]. The majority of "incalc" error codes repeated with a numeric glucose result on both GEM analyzers [(79.7% (122/153) vs 75.2% (94/125)]. Among specimens experimentally depleted of p O 2, the GEM 5000 under-recovered glucose by up to 30% compared to the Siemens Vista and were not flagged by an "incalc" code. The algorithm in the GEM ®PremierTM series of analyzers that flags specimens at risk for glucose under-recovery due to low p O 2 does not reliably detect specimens at risk for glucose under-recovery. [ABSTRACT FROM AUTHOR]

The global epidemic of obesity is tightly associated with numerous comorbidities, such as type II diabetes, cardiovascular diseases and the metabolic syndrome. Among the key features of obesity, some studies have suggested the abnormal expansion of adipose-tissue-induced local endogenous hypoxic, while other studies indicated endogenous hyperoxia as the opposite trend. Endogenous hypoxic aggravates dysfunction in adipose tissue and stimulates secretion of inflammatory molecules, which contribute to obesity. In contrast, hypoxic exposure combined with training effectively generate exogenous hypoxic to reduce body weight and downregulate metabolic risks. The (patho)physiological effects in adipose tissue are distinct from those of endogenous hypoxic. We critically assess the latest advances on the molecular mediators of endogenous hypoxic that regulate the dysfunction in adipose tissue. Subsequently we propose potential therapeutic targets in adipose tissues and the small molecules that may reverse the detrimental effect of local endogenous hypoxic. More importantly, we discuss alterations of metabolic pathways in adipose tissue and the metabolic benefits brought by hypoxic exercise. In terms of therapeutic intervention, numerous approaches have been developed to treat obesity, nevertheless durability and safety remain the major concern. Thus, a combination of the therapies that suppress endogenous hypoxic with exercise plans that augment exogenous hypoxic may accelerate the development of more effective and durable medications to treat obesity and comorbidities. [ABSTRACT FROM AUTHOR]

• The pH, PO 2 and PCO 2 multifunctional fluorescent capillary sensing system are designed for real-time blood gas analysis. • The sensing system possesses sensitive fluorescence response to pH, O 2 and CO 2. • The pH, PO 2 and PCO 2 changes in buffer, in vitro, and in vivo can be detected by measuring the fluorescence signals of sensing probe. • The in vivo blood gas analysis in four disease models can be assessed efficiently by the sensing system. Real-time blood gas analysis is of great significance in disease diagnosis and treatment. Here we have developed a pH, PO 2 and PCO 2 multifunctional fluorescent capillary sensing system. The pH, O 2 and CO 2 fluorescent indicators with same excitation wavelength are fixed into a single capillary tube. The sensing system possesses sensitive fluorescence response to pH, O 2 and CO 2 , and the changes of pH, O 2 and CO 2 in buffer, in vitro, and in vivo can be detected simultaneously by measuring the fluorescence signals of sensor probe. The PO 2 , PCO 2 and pH of rabbits in four disease models were assessed efficiently by the sensing system, exhibiting similar variation trend with the results by blood gas analyzer. Studies in living rabbit display the reasonable and favorable feasibility of capillary sensing system in real-time arterial blood gas analysis. Overall, the multifunctional fluorescent capillary sensing system exhibits significant potential in real-time arterial blood gas analysis and clinical application of disease diagnosis. [ABSTRACT FROM AUTHOR]

The spatiotemporal blood vessel formation and specification at the osteogenic and angiogenic interface of murine cranial bone defect repair were examined utilizing a high-resolution multiphoton-based imaging platform in conjunction with advanced optical techniques that allow interrogation of the oxygen microenvironment and cellular energy metabolism in living animals. Our study demonstrates the dynamic changes of vessel types, that is, arterial, venous, and capillary vessel networks at the superior and dura periosteum of cranial bone defect, suggesting a differential coupling of the vessel type with osteoblast expansion and bone tissue deposition/remodeling during repair. Employing transgenic reporter mouse models that label distinct types of vessels at the site of repair, we further show that oxygen distributions in capillary vessels at the healing site are heterogeneous as well as time- and location-dependent. The endothelial cells coupling to osteoblasts prefer glycolysis and are less sensitive to microenvironmental oxygen changes than osteoblasts. In comparison, osteoblasts utilize relatively more OxPhos and potentially consume more oxygen at the site of repair. Taken together, our study highlights the dynamics and functional significance of blood vessel types at the site of defect repair, opening up opportunities for further delineating the oxygen and metabolic microenvironment at the interface of bone tissue regeneration.

Since its apomorphic appearance in 2019, severe acute respiratory syndrome Coronavirus type 2 (SARS-CoV-2) nowadays circulates as a plesiomorphic human virus in several synapomorphic variants. The respiratory tract is the most important site of infection, the viral effects in the lungs are well described, and more than half of the patients could develop shortness of breath and dyspnea and require ventilatory support. The physiological sign of this condition is the decrease in the partial pressure of oxygen in the blood, leading to acute hypoxia, which could be a factor in the disease. In severe patients, we recorded several physiological parameters: breath frequency (BF), partial pressure of oxygen in the blood (pO2), partial pressure of carbon dioxide in the blood (pCO2), hemoglobin (Hb), heart rate (HR), and blood pressure in correlation with the olfactory threshold. We found significant correlations between reduced olfactory threshold with pO2 and hemoglobin levels, changes in heart rate, and increased HR and pCO2. These results suggest that COVID-19 causes an impaired sense of smell that decreases in threshold corresponding to the disease severity. [ABSTRACT FROM AUTHOR]

Background: In clinical practice, capillary blood taken from hyperemized earlobes (CBGE) or fingertips (CBGF) is frequently used as substitute for arterial blood (ABG) for blood gas analysis. While there is a close agreement between ABG and CBGE/CBGF regarding pH and pCO2, pO2 is often underestimated by CBG. Recently, a software tool (v-TAC®; Roche Diagnostics, Risch-Rotkreuz, Switzerland) has been developed to calculate ABG values based on a peripheral venous blood gas analysis supplemented with peripheral oxygen saturation. Objective: Here we investigate whether v-TAC can also be used to calculate ABG values from capillary blood samples. Methods: Patients (n = 85) with an indwelling arterial line were included in the study. A reference ABG sample (ABG1) was obtained, followed by CBGE, CBGF, and finally a second ABG (ABG2). Results of CBGE/CBGF before and after mathematical arterialization by v-TAC (aCBGE/aCBGF) were compared to ABG1. Results: After mathematical arterialization by v-TAC, the mean bias in pO2 between ABG1 and CBGE went down from 5.24 mm Hg (95% limit of agreement [95% LoA]: −14.19 to 24.67) to 0.18 mm Hg (95% LoA: −11.84 to 12.20) and was in a similar range as the mean bias between ABG1 and ABG2 (0.39 mm Hg [95% LoA: −13.46 to 14.24]). Differences in pH and pCO2 between arterial and capillary samples were small before and after mathematical arterialization. Very similar results were obtained when using fingertip instead of earlobe capillary blood. Conclusion: In summary, v-TAC can be used for mathematical arterialization of capillary blood samples for blood gas analysis resulting in increased diagnostic accuracy for pO2. [ABSTRACT FROM AUTHOR]

The letter discusses the quality demands for arterial partial pressure of oxygen (pO2) and the lack of criteria available for defining necessary limits for bias and coefficient of variation (CV%). The authors propose quality specifications based on clinical judgments and known information on normal ranges. They suggest that the quality demands for arterial pO2 should include a bias of less than 0.2 kPa, a CV of less than 4%, and a total error of less than 0.5 kPa at levels below 5 kPa. These specifications have been implemented in their laboratories until more scientifically based data becomes available. [Extracted from the article]

Introduction: Blood gas analysis (BGA) is an essential test used for years to provide vital information in critically ill patients. However, the instability of the blood gases is a problem. We aimed to evaluate time and temperature effects on blood gas stability. Materials and methods: Arterial blood was collected from 20 patients into syringes. Following BGA for baseline, syringes were divided into groups to stand at 4°C and 22°C for 30, 60, 90, 120 minutes. All were tested for pH, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), oxygen saturation (sO2), oxyhemoglobin (O2Hb), sodium, potassium, glucose, lactate, oxygen tension at 50% hemoglobin saturation (p50), and bicarbonate. A subgroup analysis was performed to detect the effect of air on results during storage. Percentage deviations were calculated and compared against the preset quality specifications for allowable total error. Results: At 4°C, pO2 was the least stable parameter. At 22°C, pO2 remained stable for 120 min, pH and glucose for 90 min, lactate and pCO2 for 60 min. Glucose and lactate were stable when chilled. Air bubbles interfered pO2 regardless of temperatures, whereas pCO2 increased significantly at 22°C after 30 min, and pH decreased after 90 min. Bicarbonate, sO2, O2Hb, sodium, and potassium were the unaffected parameters. Conclusions: Correct BGA results are essential, and arterial sample is precious. Therefore, if immediate analysis cannot be performed, up to one hour, syringes stored at room temperature will give reliable results when care is taken to minimize air within the blood gas specimen. [ABSTRACT FROM AUTHOR]

The present study was done to assess the effect of the tetralogy of Fallot on some arterial blood measurements including pH, the partial pressure of carbon dioxide (pCO2), the partial pressure of oxygen (pO2), Base excess (B.E.), Red blood cells (RBC), Packed cell volume (PCV), and Hemoglobin (Hb) concentration in the Erbil City of Iraq. For this purpose 80 (40 males and 40 females) patients with tetralogy of Fallot were used in this study. The study was conducted from March /2018 to October 2020. The study was carried out in the Cardiac Center in Erbil city. The studied parameters were estimated before and two to three weeks after surgical correction of Fallot. A dependent t-test was used for data analysis. The results showed that males and females with tetralogy of Fallot after surgical correction have significantly lower pCO2, RBC, PCV, and Hb concentration, while the concentration of pO2 and the value of Base Excess were significantly higher after surgical correction in comparison with the value before surgery. Moreover, males showed a significantly higher concentration of the RBC, PCV, and hemoglobin than that of the females after surgical correction. Conclusions: Surgery repair of tetralogy of Fallot restore the arterial blood measurements pCO2, pO2, Base Excess, RBC, PCV, and Hb concentration to the normal value in males and females.

Abstract Coal, especially the inertinite in it, is highly sensitive to climate changes, showing an obvious response to paleoclimate conditions, in particular, to paleo-oxygen concentration (pO2). In this study, the inertinite abundance data of typical coal-forming periods in China were systematically collected and analyzed. Its characteristics and control factors were studied, and its evolution was established. Based on inertinite abundance data, pO2 evolution curves of various coal-forming periods in China were established, which fluctuated between 15% and 30% during the entire Phanerozoic. The inertinite abundance in coal deposits during Paleozoic in China was basically consistent with that of other areas of the world, while it was quite different globally from the Mesozoic to the Cenozoic. The results show that the inertinite abundance in coal deposits is controlled by pO2 and other factors including climatic zones, plant differentiation, sedimentary environments, and tectonic activities. The inertinite abundance in coal deposits in China during the Jurassic was high, suggesting dry paleoclimate of inland China.

Background and purpose: Longitudinal Positron Emission Tomography (PET) with hypoxia-specific radiotracers allows monitoring the time evolution of regions of increased radioresistance and may become fundamental in determining the radiochemotherapy outcome in Head-and-Neck Squamous Cell Carcinoma (HNSCC). The aim of this study was to investigate the evolution of the hypoxic target volume on oxygen partial pressure maps (pO2-HTV) derived from 18FMISO-PET images acquired before and during radiochemotherapy and to uncover correlations between extent and severity of hypoxia and treatment outcome. Material and methods: 18FMISO-PET/CT images were acquired at three time points (before treatment start, in weeks two and five) for twenty-eight HNSCC patients treated with radiochemotherapy. The images were converted into pO2 maps and corresponding pO2-HTVs (pO2-HTV1, pO2-HTV2, pO2-HTV3) were contoured at 10 mmHg. Different parameters describing the pO2-HTV time evolution were considered, such as the percent and absolute difference between the pO2-HTVs (%HTVi,j and HTVi-HTVj with i,j = 1, 2, 3, respectively) and the slope of the linear regression curve fitting the pO2-HTVs in time. Correlations were sought between the pO2-HTV evolution parameters and loco-regional recurrence (LRR) using the Receiver Operating Characteristic method. Results: The Area Under the Curve values for %HTV1,2, HTV1-HTV2, HTV1-HTV3 and the slope of the pO2-HTV linear regression curve were 0.75 (p = 0.04), 0.73 (p = 0.02), 0.73 (p = 0.02) and 0.75 (p = 0.007), respectively. Other parameter combinations were not statistically significant. Conclusions: The pO2-HTV evolution during radiochemotherapy showed predictive value for LRR. The changes in the tumour hypoxia during the first two treatment weeks may be used for adaptive personalized treatment approaches.

PurposeAt exercise onset, intramuscular oxidative energy production responds relatively slowly in comparison with the change in adenosine triphosphate demand. To determine whether the slow kinetics of oxidative adenosine triphosphate production is due to inadequate O2 supply or metabolic inertia, we studied the kinetics of intramyocellular deoxygenation (deoxy-myoglobin (Mb)) and metabolism (phosphocreatine (PCr)) using proton (1H) and phosphorus (31P) magnetic resonance spectroscopy in six healthy subjects (33 ± 5 yr).MethodsSpecifically, using dynamic plantarflexion exercise, rest to exercise and recovery were assessed at both 60% of maximum work rate (moderate intensity) and 80% of maximum work rate (heavy intensity).ResultsAt exercise onset, [PCr] fell without delay and with a similar time constant (τ) at both exercise intensities (approximately 33 s). In contrast, the increase in deoxy-Mb was delayed at exercise onset by 5-7 s, after which it increased with kinetics (moderate τ = 37 ± 9 s; heavy τ = 29 ± 6 s) that was not different from τPCr (P > 0.05). At cessation, deoxy-Mb recovered without time delay and more rapidly (τ = ∼20 s) than PCr (τ = ∼33 s) (P < 0.05).ConclusionsUsing a unique combination of in vivo magnetic resonance spectroscopy techniques with high time resolution, this study revealed a delay in intramuscular deoxygenation at the onset of exercise and rapid reoxygenation kinetics upon cessation. Together, these data imply that intramuscular substrate-enzyme interactions, and not O2 availability, determine the exercise onset kinetics of oxidative metabolism in healthy human skeletal muscles.

The global epidemic of obesity is tightly associated with numerous comorbidities, such as type II diabetes, cardiovascular diseases and the metabolic syndrome. Among the key features of obesity, some studies have suggested the abnormal expansion of adipose-tissue-induced local endogenous hypoxic, while other studies indicated endogenous hyperoxia as the opposite trend. Endogenous hypoxic aggravates dysfunction in adipose tissue and stimulates secretion of inflammatory molecules, which contribute to obesity. In contrast, hypoxic exposure combined with training effectively generate exogenous hypoxic to reduce body weight and downregulate metabolic risks. The (patho)physiological effects in adipose tissue are distinct from those of endogenous hypoxic. We critically assess the latest advances on the molecular mediators of endogenous hypoxic that regulate the dysfunction in adipose tissue. Subsequently we propose potential therapeutic targets in adipose tissues and the small molecules that may reverse the detrimental effect of local endogenous hypoxic. More importantly, we discuss alterations of metabolic pathways in adipose tissue and the metabolic benefits brought by hypoxic exercise. In terms of therapeutic intervention, numerous approaches have been developed to treat obesity, nevertheless durability and safety remain the major concern. Thus, a combination of the therapies that suppress endogenous hypoxic with exercise plans that augment exogenous hypoxic may accelerate the development of more effective and durable medications to treat obesity and comorbidities.

Excessive adiposity is associated with altered oxygen tension and comorbidities in humans. In contrast, marine mammals have high adiposity with no apparent detrimental effects. However, partial pressure of oxygen (Po2) in their subcutaneous adipose tissue (blubber) and its relationship with fatness have not been reported. We measured Po2 and temperature at different blubber depths in 12 healthy juvenile grey seals. Fatness was estimated from blubber thickness and morphometric parameters. Simultaneously, we monitored breathing pattern; heart rate and arterial blood saturation with a pulse oximeter; and relative changes in total hemoglobin, deoxyhemoglobin, and oxyhemoglobin in blubber capillaries using near‐infrared spectroscopy (NIRS) as proxies for local oxygenation changes. Blubber Po2 ranged from 14.5 to 71.4 mmHg (39.2 ± 14.1 mmHg), which is similar to values reported in other species. Blubber Po2 was strongly and negatively associated with fatness (LME: p < 0.0001, R2marginal = 0.53, R2conditional = 0.64, n = 10), but not with blubber depth. No other parameters explained variability in Po2, suggesting arterial blood and local oxygen delivery did not vary within and between measurements. The fall in blubber Po2 with increased fatness in seals is consistent with other animal models of rapid fat deposition. However, the Po2 levels at which blubber becomes hypoxic and consequences of low blubber Po2 for its health and function, particularly in very fat individuals, remain unknown. How seals avoid detrimental effects of low oxygen tension in adipose tissue, despite their high and fluctuating adiposity, is a fruitful avenue to explore. [ABSTRACT FROM AUTHOR]

Abstract Excessive adiposity is associated with altered oxygen tension and comorbidities in humans. In contrast, marine mammals have high adiposity with no apparent detrimental effects. However, partial pressure of oxygen (Po2) in their subcutaneous adipose tissue (blubber) and its relationship with fatness have not been reported. We measured Po2 and temperature at different blubber depths in 12 healthy juvenile grey seals. Fatness was estimated from blubber thickness and morphometric parameters. Simultaneously, we monitored breathing pattern; heart rate and arterial blood saturation with a pulse oximeter; and relative changes in total hemoglobin, deoxyhemoglobin, and oxyhemoglobin in blubber capillaries using near‐infrared spectroscopy (NIRS) as proxies for local oxygenation changes. Blubber Po2 ranged from 14.5 to 71.4 mmHg (39.2 ± 14.1 mmHg), which is similar to values reported in other species. Blubber Po2 was strongly and negatively associated with fatness (LME: p

Since its apomorphic appearance in 2019, severe acute respiratory syndrome Coronavirus type 2 (SARS-CoV-2) nowadays circulates as a plesiomorphic human virus in several synapomorphic variants. The respiratory tract is the most important site of infection, the viral effects in the lungs are well described, and more than half of the patients could develop shortness of breath and dyspnea and require ventilatory support. The physiological sign of this condition is the decrease in the partial pressure of oxygen in the blood, leading to acute hypoxia, which could be a factor in the disease. In severe patients, we recorded several physiological parameters: breath frequency (BF), partial pressure of oxygen in the blood (pO2), partial pressure of carbon dioxide in the blood (pCO2), hemoglobin (Hb), heart rate (HR), and blood pressure in correlation with the olfactory threshold. We found significant correlations between reduced olfactory threshold with pO2 and hemoglobin levels, changes in heart rate, and increased HR and pCO2. These results suggest that COVID-19 causes an impaired sense of smell that decreases in threshold corresponding to the disease severity.

Coal, especially the inertinite in it, is highly sensitive to climate changes, showing an obvious response to paleoclimate conditions, in particular, to paleo-oxygen concentration (pO2). In this study, the inertinite abundance data of typical coal-forming periods in China were systematically collected and analyzed. Its characteristics and control factors were studied, and its evolution was established. Based on inertinite abundance data, pO2 evolution curves of various coal-forming periods in China were established, which fluctuated between 15% and 30% during the entire Phanerozoic. The inertinite abundance in coal deposits during Paleozoic in China was basically consistent with that of other areas of the world, while it was quite different globally from the Mesozoic to the Cenozoic. The results show that the inertinite abundance in coal deposits is controlled by pO2 and other factors including climatic zones, plant differentiation, sedimentary environments, and tectonic activities. The inertinite abundance in coal deposits in China during the Jurassic was high, suggesting dry paleoclimate of inland China. [ABSTRACT FROM AUTHOR]

The precipitation of metallic Fe from the FeO t -SiO 2 -CaO-Al 2 O 3 –ZnO-(Cr 2 O 3) slag system can cause serious problems for the slag tapping and slag valorization. This study examines the impact of slag chemistry, oxygen partial pressure (pO 2), and temperature on Fe generation and ZnO reduction in the FeO t -SiO 2 -CaO-Al 2 O 3 –ZnO-(Cr 2 O 3) slag system and compares the results with those from FactSage calculation. Metallic Fe is observed in CaO-free slag with a FeO/(Al 2 O 3 +SiO 2) ratio above 1.22 under pO 2 of 1 × 10−12 atm at 1250 °C. As the CaO content increases to 29.7 wt%, the critical FeO/(Al 2 O 3 +SiO 2) ratio for Fe generation decreases to 0.53. The critical temperature for Fe precipitation under pO 2 of 1 × 10−12 atm is measured to be between 1200 and 1250 °C, while the critical pO 2 to prevent the metallic Fe formation was calculated to be in excess of 5 × 10−13 and 1 × 10−12 atm at 1200 and 1250 °C, respectively. ZnO can be reduced into metallic Zn at 1250 °C under pO 2 of 1 × 10−10 atm or below. The operational conditions for Zn fuming of the FeO t -SiO 2 -CaO-Al 2 O 3 –ZnO slags without Fe formation are recommended to be pO 2 of 1 × 10−12 atm at 1200 °C. [Display omitted] [ABSTRACT FROM AUTHOR]

Oxygen (O2) exchange between capillaries and muscle cells in exercising muscles is of great interest for physiology and kinesiology. However, methodical limitations prevent O2 measurements on the millisecond scale. To bypass the constraints of quasi-continuous recording, progressive measurements of O2 partial pressure (PO2) in rhythmically contracting skeletal muscle were compiled to describe the O2 kinetics surrounding and including a single muscle contraction. Phosphorescence quenching microscopy measured PO2 in the interstitium of the rat spinotrapezius muscle. Measurements were triggered by contraction-inducing electrical pulses. For the first 60 seconds, measurement preceeded stimulation. After 60, measurement followed with a progressive 20 ms increment. Thus, the first 60 measurements describe the overall PO2 response to electrical stimulation initiated after a 10 second rest period, while 61--100 (stroboscopic mode) were compiled into a single 800 ms profile of the PO2 transient surrounding muscle contraction. Thirty seconds of stimulated contractions decreased interstitial PO2 from a baseline of 71 ± 1.4 mmHg to an "active" steady-state of 43 ± 1.5 mmHg. The stroboscopic mode compilation revealed an unexpected post-contractile rise in PO2 as a 205 ms spike with a maximum amplitude of 58 ± 3.8 mmHg at 68 ms, which restored 58% of the PO2 drop from baseline. Interpretation of this phenomenon is based on classical experiments by G.V. Anrep (1935), who discovered the rapid thrust of blood flow associated with muscle contraction. In addition to the metabolic implications during exercise, the physiological impact of these PO2 spikes may grow with an increased rate of rhythmical contractions in muscle or heart. New&Noteworthy: The principal finding is a spike of interstitial PO2, produced by a twitch in a rhythmically contracting muscle. A possible mechanism is flushing capillaries with arterial blood by mechanical forces. A technical novelty is the PO2 measurement with a "stroboscopic mode" and progressively increasing delay between stimulator pulse and PO2 measuring. That permitted a 20 ms time resolution for a 205 ms spike duration, using an excitation flash rate one per second. [ABSTRACT FROM AUTHOR]

Hypoxia is associated with increased erythropoietin (EPO) release to drive erythropoiesis. At high altitude, EPO levels first increase and then decrease, although erythropoiesis remains elevated at a stable level. The roles of hypoxia and related EPO adjustments are not fully understood, which has contributed to the formulation of the theory of neocytolysis. We aimed to evaluate the role of oxygen exclusively on erythropoiesis, comparing in vitro erythroid differentiation performed at atmospheric oxygen, a lower oxygen concentration (three percent oxygen) and with cultures of erythroid precursors isolated from peripheral blood after a 19-day sojourn at high altitude (3450 m). Results highlight an accelerated erythroid maturation at low oxygen and more concave morphology of reticulocytes. No differences in deformability were observed in the formed reticulocytes in the tested conditions. Moreover, hematopoietic stem and progenitor cells isolated from blood affected by hypoxia at high altitude did not result in different erythroid development, suggesting no retention of a high-altitude signature but rather an immediate adaptation to oxygen concentration. This adaptation was observed during in vitro erythropoiesis at three percent oxygen by a significantly increased glycolytic metabolic profile. These hypoxia-induced effects on in vitro erythropoiesis fail to provide an intrinsic explanation of the concept of neocytolysis.

Abstract Introduction Incidence of high altitude‐related sickness is increasing due to more number of people visiting the areas of high altitude which may result in life‐threatening conditions including acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), high altitude cerebral edema (HACE), and High‐altitude pulmonary hypertension (HAPH). We hypothesized that an advanced yoga regimen may be beneficial in dealing with the physiology of acclimatization. Methods Anthropometric, Biochemical, and Psychological assessments were carried out in 48 participants before and after the advance meditation program (AMP) in the experimental group. Individuals with an age range of 20–65 years with no comorbidities were included in the study. Participants were exposed to AMP for 4 days. All assessments were carried out at the baseline and after the course. Prakriti was constituted for all participants using a standard questionnaire. The study was carried out after obtaining the written informed consent as per the guidelines outlined by the Institute Ethics Committee. Results Po2 and glucose levels were found significantly reduced along with changes in the Happiness index, anxiety, and mental well‐being. However, participants with lowered Po2, after 4 days of mindfulness intervention, showed a positive outcome measured by the established scales of anxiety, happiness, and information processing. Psychometric or Prakriti wise analysis revealed that subject with “Pitta” constitution exposed to high altitude and advance meditation showed changes in more parameters than “Vatta” or “Kapha” Constitution. Conclusions Advance meditation in the high altitude zone confers biochemical and neuro‐cognitive benefits. Molecular studies may require to understand the role of hypoxic condition in improving the disease state.

Introduction: Incidence of high altitude‐related sickness is increasing due to more number of people visiting the areas of high altitude which may result in life‐threatening conditions including acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), high altitude cerebral edema (HACE), and High‐altitude pulmonary hypertension (HAPH). We hypothesized that an advanced yoga regimen may be beneficial in dealing with the physiology of acclimatization. Methods: Anthropometric, Biochemical, and Psychological assessments were carried out in 48 participants before and after the advance meditation program (AMP) in the experimental group. Individuals with an age range of 20–65 years with no comorbidities were included in the study. Participants were exposed to AMP for 4 days. All assessments were carried out at the baseline and after the course. Prakriti was constituted for all participants using a standard questionnaire. The study was carried out after obtaining the written informed consent as per the guidelines outlined by the Institute Ethics Committee. Results: Po2 and glucose levels were found significantly reduced along with changes in the Happiness index, anxiety, and mental well‐being. However, participants with lowered Po2, after 4 days of mindfulness intervention, showed a positive outcome measured by the established scales of anxiety, happiness, and information processing. Psychometric or Prakriti wise analysis revealed that subject with "Pitta" constitution exposed to high altitude and advance meditation showed changes in more parameters than "Vatta" or "Kapha" Constitution. Conclusions: Advance meditation in the high altitude zone confers biochemical and neuro‐cognitive benefits. Molecular studies may require to understand the role of hypoxic condition in improving the disease state. [ABSTRACT FROM AUTHOR]

Phase equilibria in the CaO–SiO 2 –La 2 O 3 –Nb 2 O 5 system are important for the utilization of Nb and Rare Earth resources. In the present work, phase equilibria in the CaO–SiO 2 –La 2 O 3 –Nb 2 O 5 system at 1473 K in H 2 (pO 2 = 10−15.47atm) were studied by the equilibrium experiment. SEM, EDS and XRD analysis were employed to identify the equilibrium phase relations. The isothermal spatial phase diagram of the CaO–SiO 2 –La 2 O 3 –Nb 2 O 5 system and the isothermal section of CaO–SiO 2 –Nb 2 O 5 -(5%, 10%) La 2 O 3 pseudo-ternary system were constructed. A total of eight equilibrium phase regions were determined, including Liquid + CaNb 2 O 6 +CaSiO 3 +LaNbO 4 region, Liquid + CaNb 2 O 6 +SiO 2 +CaSiO 3 region, Liquid + CaSiO 3 +CaNb 2 O 6 region, Liquid + CaSiO 3 +SiO 2 region, Liquid + CaNb 2 O 6 +SiO 2 region, Liquid + CaSiO 3 region, Liquid + SiO 2 region and Liquid + CaNb 2 O 6 region. Additionally, the influence of pO 2 on equilibrium composition and temperature was also investigated considering its significant effect on phase equilibria in the slag system with variable valence elements. The results indicated that higher external pO 2 can increase the equilibrium O content in a slag system, while higher equilibrium temperature corresponds to higher equilibrium pO 2. Besides, the relationship between phase equilibria shown in the traditional slag system and in the related generalized alloy system was also revealed. The present experimental data can help further study on Nb-bearing and RE-bearing slag systems, and the theoretical conclusions will help the development of thermodynamic models. [ABSTRACT FROM AUTHOR]

Introduction: Roughly 13% of all battlefield injuries include some form of ocular trauma. Ocular tissue preservation is critical for wound healing for warfighters with ocular injuries. Our team hypothesized that oxygen plays a vital role in ocular tissue preservation and wound healing and has developed a supersaturated oxygen emulsion (SOE) for the topical treatment of ocular trauma.Materials and Methods: The partial pressure of oxygen (PO2) was measured in the SOE. Safety and efficacy studies were carried out in primary human corneal epithelial (HCE) cells, as the outermost layer is the first barrier to chemical and mechanical injury. Western blot, scratch assay, and MTT assays were conducted to determine the effect of the SOE on various molecular markers, the rate of scratch closure, and cellular viability, respectively.Results: Data indicate that the SOE releases oxygen in a time-dependent manner, reaching a partial pressure within the emulsion over four times atmospheric levels. Studies in HCE cells indicate that application of the SOE does not lead to DNA damage, promote cell death, or hinder the rate of scratch closure and enhances cellular viability. Preliminary studies were carried out with chloropicrin (CP; developed as a chemical warfare agent and now a commonly used pesticide) as a chemical agent to induce ocular injury in HCE cells. CP exposures showed that SOE treatment reverses CP-induced DNA damage, apoptotic cell death, and oxidative stress markers.Conclusions: Maintaining adequate tissue oxygenation is critical for tissue preservation and wound repair, especially in avascular tissues like the cornea. Further studies examining the application of the SOE in corneal injury models are warranted. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance (EPR) spectroscopy using oxygen-sensing implants can provide reliable and repeated measurements of the partial pressure of oxygen (pO2) over a period of months or longer; however, it does not provide accurate information about the distribution of tissue oxygenation. While EPR imaging has the capability to provide spatially resolved oxygen data, it is time-consuming and not optimized for discrete number of implants. Previous reports suggest multi-site algorithms, which would require either the implants to be aligned in a certain way so as to deconvolve them using a linear magnetic field gradient or sparse imaging of the implants from a small number of 3D projections. In this paper, we present a simpler and much faster method to estimate the pO2 histogram from a composite, single-scan EPR spectrum measured without applying field gradients to separate the EPR signals from multiple randomly placed oxygen-sensing implants. The method is optimized for a discrete number of implants, validated using simulations, experimental phantoms and in animal models. The results established the composite spectral fitting algorithm as a reliable and robust tool for multi-site oximetry. [ABSTRACT FROM AUTHOR]

Background: The extent of error, from collection to processing, when measuring PO2, PCO2 and pH in arterial blood samples drawn from critically ill patients with sepsis and leucocytosis, is unknown. Methods: Twenty-nine patients with sepsis and a leucocyte count > 12 000/mm³, who had routine arterial blood analysis were included in the study. Blood was drawn into two 1 ml heparinised glass syringes. One syringe was cooled on ice and tested at 60 minutes. The other syringe was used for analysis at 0, 10, 30 and 60 minutes. Differences in measurements, from the Time-0 results, were described. For PO2, linear mixed models estimated the impact of time to processing, controlling for the potentially confounding and moderating effects of Time-0 leucocyte count and fractional inspired oxygen concentration respectively. Results: PO2 exhibited the most pronounced changes over time at ambient temperature: The mean (SD) relative differences at 10, 30 and 60 minutes were -4.72 (8.82), -13.66 (10.25), and -25.12 (15.55)% respectively; and mean (SD) absolute differences -0.88 (1.49), -2.37 (1.89) and -4.32 (3.06) kPa. For pH, at 60 minutes, the mean (SD) relative and absolute differences were -0.27 (0.45)% and -0.02 (0.03) respectively; for PCO2, 6.16 (7.80)% and 0.25 (0.35) kPa. The median differences for the on-ice 60-minute sample for pH and PCO2 were 0.019 and -0.12 (both P < 0.001), and for PO2 0.100 (P: 0.216). The model estimated that average PO2 decreased by 5% per 10 minute delay in processing (95% CI for effect: 0.94 to 0.96; P < 0.001) at the average leucocyte count, with more rapid declines at higher counts, though with substantial inter-patient variation. Conclusion: Delayed blood gas analysis in samples stored at ambient temperature results in a statistically and clinically significant progressive decrease in arterial PO2, which may alter clinical decision-making in septic patients. [ABSTRACT FROM AUTHOR]

Due to the high growth rate and environmental‐friendly, fluorine‐free metal‐organic decomposition routes (FF‐MOD) have attracted more attention for growth of high‐quality YBa2Cu3O7‐δ (YBCO) films. Few works have been performed when using technical substrates. In this study, correlation among the sintering process, microstructure, and superconductivity of the YBCO was systematically established on the technical substrates capped with CeO2 layer. We found that the optimal process conditions are mainly related to the enhanced transient liquid phase and BaCeO3. Combined X‐ray diffraction and scanning electron microscopy analyses indicate that high‐quality growth of YBCO film is a trade‐off of two different competition phenomena during sintering: (a) the presence of enhanced transient liquid phase, (b) the formation of BaCeO3 at the interface. The former is beneficial to YBCO epitaxial growth/structure rearrangement, while the latter should be suppressed in view of minimizing YBCO partial decomposition triggered by the interfacial reaction. Moreover, we confirmed that both two aforementioned phenomena are somehow associated with the cross‐linkage between the sintering temperature and pO2 during the YBCO conversion. According to this systemic study, the key parameters are defined to avoid the BaCeO3 formation prior to the YBCO orientation nucleation. Structure and superconductivity of the YBCO film were also investigated. Remarkably, a high Jc value of 3.69 mA/cm2 (77 K, sf) was obtained in the YBCO film grown on the CeO2 technical substrate deposited under optimized deposition conditions, which is rather comparable with that on the LaAlO3 single crystal. TEM cross‐sectional observation reveals that the enhanced Jc (B) properties of the YBCO film are mainly contributed by high density of short stacking faults. This work demonstrates the feasibility of FF‐MOD to fabricate high‐performance YBCO films on the CeO2‐buffered technical substrate. [ABSTRACT FROM AUTHOR]

Tungsten oxide (WO 3) thin films were prepared on Corning (CG) and Fluorine doped tin oxide (FTO) glass substrates at partial pressure of oxygen (pO 2) 4 × 10−2 Pa and 8 × 10−2 Pa using DC magnetron sputtering (DCMs). In this work, we have varied the deposition parameters like pO 2 , target currents, and temperature. At pO 2 4 × 10−2 Pa and 8 × 10−2 Pa samples were deposited at target currents of 50 mA and 100 mA, the maintained growth conditions are RT (substrate temperature 28 °C), Pre annealed (substrate temperature 400 °C), and Post annealed (annealing temperature 400 °C). The samples were systematically characterized for vibrational, structural, optical, and Electrochromic (EC) properties by using Raman, XRD, Uv-Vis spectrometer, and Electrochemical analyzer respectively. XRD analysis reveals that RT-deposited samples show amorphous nature and pre & post-annealed samples show a crystalline nature for both pO 2. Optical transmittance was higher at RT-deposited samples at 50 mA (94% & 92%) and lower at 100 mA (87% & 85%) at the wavelength of 600 nm for both pO 2. From CV analysis higher cathodic peak current density was observed in RT-deposited samples at 50 mA (−6.49 mAcm−2 & -13.80 mAcm−2) and lower at 100 mA (−5.25 mAcm−2 & -12.88 mAcm−2) for both pO 2. The diffusion coefficient was observed at a higher target current at 100 mA (1.06 × 10−7 cm2/s & 9.20 × 10−8 cm2/s). For annealed samples optical and EC properties were decreased for both pO 2. • Deposition tungsten oxide thin films using DC Magnetron Sputtering. • Deposition of tungsten oxide thin films at different oxygen partial pressure 4 × 10−4 mbar and 8 × 10−4 mbar. • Studied optical and electrochemical properties of both oxygen partial pressure. [ABSTRACT FROM AUTHOR]

Introduction: Traditional validation of umbilical cord blood samples with positive veno-arterial ΔpH and arterio-venous ΔpCO2 values confirms the source of samples, whereas negative Δvalues represent mix-up of samples. To investigate whether this is true, the distributions of V-A ΔpO2 and A-V Δlactate were also explored and related to clinical characteristics. In addition, different cord blood sampling techniques were evaluated.Material and Methods: Register study with cord blood acid-base and clinical data from 27 233 newborns. Clinical characteristics were related to positive, zero and negative Δvalues. Blood samplings from unclamped and double-clamped cords were compared. A two-sided P < 0.05 was considered significant.Results: ΔpH and ΔpCO2 values distributed into positive, around zero, and negative sub-populations, with significant differences in pH and clinical characteristics between sub-populations. No such sub-populations were distinguished for ΔpO2 and Δlactate. The 2.5th and 5th ΔpH percentiles were 0.013 and 0.022, respectively, and for ΔpCO2 0.30 and 0.53 kPa. Applying 5th percentile criteria resulted in 3.5% of "approved" cases showing a ΔpO2  ≤ 0. Puncture and sampling of the unclamped cord resulted in significantly better sample quality.Conclusions: Unphysiological negative ΔpO2 values occurred despite correct validation with traditional criteria. Δlactate cannot be used for validation because both positive and negative values are physiological. Positive/around zero/negative ΔpH and ΔpCO2 sub-populations were associated with significant differences in pH and clinical characteristics, indicating that defective sampling and sample handling are not the sole explanations for negative Δvalues. Prompt puncture and sampling of the unclamped cord resulted in best sample quality. [ABSTRACT FROM AUTHOR]

For obvious reasons, in vivo measurements of placental oxygenation are extremely rare and hence, scientists need to focus on the few studies that revealed at least some data on the topic. The scarcity of real in vivo data resulted in the development of hypotheses on placental oxygenation that blocked an objective view on the topic for decades. Only now, new hypotheses are emerging adding new views and ideas on the topic. Especially in the field of preeclampsia, hypotheses on placental oxygenation have mislead a whole generation of scientists. This review article displays the available in vivo placental oxygen data from 8 to 40 weeks of gestation. It also compares these physiological oxygen concentrations, called physioxia, with the situation in pre-placental hypoxia, i.e. pregnancies at high altitude. Finally, it summarizes what we know today about oxygen measurements in cases with preeclampsia. In early-onset preeclampsia cases, all in vivo data available today point to increased oxygen values in the intervillous space of the placenta. This is due to a reduced oxygen transfer of the placental barrier from maternal to fetal blood, resulting in hypoxia of fetal blood and the fetus. • Normal placental oxygen levels show variations between below 20 mmHg and 60 mmHg during pregnancy. • Early-onset preeclampsia FGR is associated with increased pO 2 in intervillous maternal blood and decreased pO 2 of fetal blood. • Early-onset preeclampsia is not associated with placental hypoxia, i.e. lower oxygen values in maternal blood in the intervillous space. • Late-onset preeclampsia is associated with placental oxygenation values similar to healthy term pregnancies. [ABSTRACT FROM AUTHOR]

ABSTRACTIntroduction:The results of blood gas analysis using different instrumentation can vary widely due to the methodological differences, the calibration procedures and the use of different configurations for each type of instrument.Objective:The objective of this study was to evaluate multiple analytical systems for measurement of blood gases, electrolytes and metabolites in accordance with the accreditation program (PALC) of Sociedade Brasileira de Patologia Clínica/Medicina Laboratorial (SBPC/ML).Materials and methods:20 samples were evaluated in three ABL800 Flex (Radiometer Medical ApS, Denmark) blood gas analyzers, and the results were compared with those of the device in use, which was considered the reference. The analysis of variance (Anova) was applied for statistical purposes, as well as the calculation of mean, standard deviation and coefficient of variation.Results:The p values obtained in the statistical analysis were: pH = 0.983, pO2 = 0.991, pCO2 = 0.353, lactate = 0.584, glucose = 0.995, ionized calcium = 0.983, sodium = 0.991, potassium = 0.926, chlorine = 0.029.Conclusion:The evaluation of multiple analytical systems is an essential procedure in the clinical laboratory for quality assurance and accuracy of the results.

Objective The objective of this study was to investigate the relationship between umbilical cord partial pressure of oxygen (pO2) at delivery and neonatal morbidity. Study Design This is a secondary analysis of a prospective cohort study of term deliveries with universal cord gas collection between 2010 and 2014. The primary composite outcome of neonatal morbidity included neonatal death, meconium aspiration syndrome, intubation, mechanical ventilation, hypoxic-ischemic encephalopathy, and hypothermia treatment. Umbilical artery (UA), vein (UV), UV minus UA (κ) pO2, and hypoxemia (pO2 fifth percentile) were compared between patients with and without neonatal morbidity. Areas under the receiver-operating characteristic curves were used to assess the predictive ability of pO2. Results Of 7,789 patients with paired umbilical cord pO2, 106 (1.4%) had the composite neonatalmorbidity. UA pO2 was significantly lower in patients with neonatal morbidity compared with those without (median [interquartile range]: 16 (12, 21) vs. 19 (15, 24) mm Hg, p < 0.001). There was no difference in median UV pO2 or κpO2 between the groups. UA and UV hypoxemia were significantly more common in patients with neonatal morbidity. UA pO2 had limited predictive ability for neonatal morbidity (area under the curve: 0.61, 95% confidence interval: 0.6-0.7). Conclusion Although UA pO2 is significantly lower in patients with neonatal morbidity, it is a poor predictor of neonatal morbidity at term. [ABSTRACT FROM AUTHOR]

Despite the increasing prevalence of hypoxia in natural habitats occupied by the American paddlefish, basal bony fish, and ram ventilator, information about its response to hypoxia is scarce. To understand the physiological and biochemical responses of juvenile paddlefish (~150 g) to acute (<24 h) and chronic hypoxia (≥24 h), blood oxygen transport, blood acid-base balance, and metabolic stress were evaluated under four different partial pressures of oxygen [pO; normoxia (148 mmHg), mild hypoxia (89 mmHg), moderate hypoxia (59 mmHg), and extreme hypoxia (36 mmHg)], all at 21 °C. Arterial blood samples were collected from paddlefish after they had been exposed to treatments for 0.25, 2, 6, 24, and 72 h, and analyzed for hematocrit, pO, total oxygen content, oxygen saturation, pCO, pH, hemoglobin, Na, K, Ca, Cl, glucose, and lactate. Mild hypoxia only caused a reduction in blood pO and oxygen saturation. Both acute and chronic moderate and extreme hypoxia caused a decrease in blood pH, pO, total oxygen content, plasma Na, and Cl at all time points. Acute moderate and extreme hypoxia resulted in an increase in blood pCO, plasma glucose, lactate, and hematocrit. Chronic exposure to moderate hypoxia resulted in an increase in plasma lactate, red blood cell count, and hemoglobin. This study shows that paddlefish are able to physiologically compensate for mild hypoxia, but exhibit secondary stress responses and are unable to return to homeostasis when exposed to both acute and chronic moderate hypoxia, and die after 3-8 h of extreme hypoxia. [ABSTRACT FROM AUTHOR]

Hypoxic environments at high altitude have significant effects on kidney injury. Following injury, renal primary cilia display length alterations. Primary cilia are mechanosensory organelles that regulate tubular architecture. The effect of hypoxia on cilia length is still controversial in cultured cells, and no corresponding in vivo study exists. Using fetal and adult sheep, we here study the effect of chronic hypobaric hypoxia on the renal injury, intracellular calcium signaling and the relationship between cilia length and cilia function. Our results show that although long-term hypoxia induces renal fibrosis in both fetal and adult kidneys, fetal kidneys are more susceptible to hypoxia-induced renal injury. Unlike hypoxic adult kidneys, hypoxic fetal kidneys are characterized by interstitial edema, tubular disparition and atrophy. We also noted that there is an increase in the cilia length as well as an increase in the cilia function in the hypoxic fetal proximal and distal collecting epithelia. Hypoxia, however, has no significant effect on primary cilia in the adult kidneys. Increased cilia length is also associated with greater flow-induced intracellular calcium signaling in renal epithelial cells from hypoxic fetuses. Our studies suggest that while hypoxia causes renal fibrosis in both adult and fetal kidneys, hypoxia-induced alteration in cilia length and function are specific to more severe renal injuries in fetal hypoxic kidneys.