HIF Oxygen Sensing Pathways in Lung Biology.

PubMed

Urrutia, Andrés A; Aragonés, Julián

2018-06-06

Cellular responses to oxygen fluctuations are largely mediated by hypoxia-inducible factors (HIFs). Upon inhalation, the first organ inspired oxygen comes into contact with is the lungs, but the understanding of the pulmonary HIF oxygen-sensing pathway is still limited. In this review we will focus on the role of HIF1α and HIF2α isoforms in lung responses to oxygen insufficiency. In particular, we will discuss novel findings regarding their role in the biology of smooth muscle cells and endothelial cells in the context of hypoxia-induced pulmonary vasoconstriction. Moreover, we will also discuss recent studies into HIF-dependent responses in the airway epithelium, which have been even less studied than the HIF-dependent vascular responses in the lungs. In summary, we will review the biological functions executed by HIF1 or HIF2 in the pulmonary vessels and epithelium to control lung responses to oxygen fluctuations as well as their pathological consequences in the hypoxic lung.

Quasi-distributed sol-gel coated fiber optic oxygen sensing probe

NASA Astrophysics Data System (ADS)

Zolkapli, Maizatul; Saharudin, Suhairi; Herman, Sukreen Hana; Abdullah, Wan Fazlida Hanim

2018-03-01

In the field of aquaculture, optical sensor technology is beginning to provide alternatives to the conventional electrical sensor. Hence, the development and characterization of a multipoint quasi-distributed optical fiber sensor for oxygen measurement is reported. The system is based on 1 mm core diameter plastic optical fiber where sections of cladding have been removed and replaced with three metal complexes sol-gel films to form sensing points. The sensing locations utilize luminophores that have emission peaks at 385 nm, 405 nm and 465 nm which associated with each of the sensing points. Interrogation of the optical sensor system is through a fiber optic spectrometer incorporating narrow bandpass emission optical filter. The sensors showed comparable sensitivity and repeatability, as well as fast response and recovery towards oxygen.

A miniature inexpensive, oxygen sensing element

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arenz, R.W.

1991-10-07

An exhaustive study was conducted to determine the feasibility of Nernst-type oxygen sensors based on ceramics containing Bi{sub 2}O{sub 3}. The basic sensor design consisted of a ceramic sensing module sealed into a metal tube. The module accommodated an internal heater and thermocouple. Thermal-expansion-matched metals, adhesives, and seals were researched and developed, consistent with sequential firings during sensor assembly. Significant effort was devoted to heater design/testing and to materials' compatibility with Pt electrodes. A systematic approach was taken to develop all sensor components which led to several design modifications. Prototype sensors were constructed and exhaustively tested. It is concluded thatmore » development of Nerst-type oxygen sensors based on Bi{sub 2}O{sub 3} will require much further effort and application of specialized technologies. However, during the course of this 3-year program much progress was reported in the literature on amperometric-type oxygen sensors, and a minor effort was devoted here to this type of sensor based on Bi{sub 2}O{sub 3}. These studies were made on Bi{sub 2}O{sub 3}-based ceramic samples in a multilayer-capacitor-type geometry and amperometric-type oxygen sensing was demonstrated at very low temperatures ({approximately} 160{degree}C). A central advantage here is that these types of sensors can be mass-produced very inexpensively ({approximately} 20--50 cents per unit). Research is needed, however, to develop an optimum diffusion-limiting barrier coating. In summary, the original goals of this program were not achieved due to unforeseen problems with Bi{sub 2}O{sub 3}-based Nernst sensors. However, a miniature amperometric sensor base on Bi{sub 2}O{sub 3} was demonstrated in this program, and it is now seen that this latter sensor is far superior to the originally proposed Nernst sensor. 6 refs., 24 figs.« less

Distributed fiber optical sensing of oxygen with optical time domain reflectometry.

PubMed

Eich, Susanne; Schmälzlin, Elmar; Löhmannsröben, Hans-Gerd

2013-05-31

In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR) which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP), immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements.

Role of oxygen free radicals in patients with acute pancreatitis

PubMed Central

Park, Byung Kyu; Chung, Jae Bock; Lee, Jin Heon; Suh, Jeong Hun; Park, Seung Woo; Song, Si Young; Kim, Hyeyoung; Kim, Kyung Hwan; Kang, Jin Kyung

2003-01-01

AIM: The generation of oxygen free radicals has been implicated in the pathogenesis of experimental pancreatitis. The aim of this study was to determine the role of oxygen free radicals in patients with acute pancreatitis. METHODS: The plasma levels of C-reactive protein (CRP), lipid peroxide (LPO), myeloperoxidase (MPO) and superoxide dismutase (SOD) were measured in 13 patients with acute pancreatitis and 14 healthy volunteers. RESULTS: Among the patients with acute pancreatitis, there were higher plasma levels of LPO and MPO and lower SOD activity in patients with severe pancreatitis than in those with mild pancreatitis. However, there was no significant difference in the serum marker of oxidative stress no matter what the etiology was. The LPO level was especially correlated with the concentration of serum CRP and CT severity index. CONCLUSION: The oxygen free radicals may be closely associated with inflammatory process and the severity of acute pancreatitis. Especially, the concentration of plasma LPO is a meaningful index for determining the severity of the disease. PMID:14562390

Prone Positioning Improves Oxygenation in Adult Burn Patients with Severe Acute Respiratory Distress Syndrome

DTIC Science & Technology

2012-01-01

Prone positioning improves oxygenation in adult burn patients with severe acute respiratory distress syndrome Diane F. Hale, MD, Jeremy W. Cannon, MD...Kevin K. Chung, MD, San Antonio, Texas BACKGROUND: Prone positioning (PP) improves oxygenation and may provide a benefit in patients with acute... positioning improves oxygenation in adult burn patients with severe acute respiratory distress syndrome 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

Distributed Fiber Optical Sensing of Oxygen with Optical Time Domain Reflectometry

PubMed Central

Eich, Susanne; Schmälzlin, Elmar; Löhmannsröben, Hans-Gerd

2013-01-01

In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR) which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP), immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements. PMID:23727953

[Acute toxicity analysis performance of CellSense biosensor with E. coli].

PubMed

Wang, Xue-Jiang; Wang, Hong; Zhao, Jian-Fu; Xia, Si-Qing; Zhao, Hong-Ning

2009-04-15

E. coli microbial electrodes for CellSense biosensor were prepared by polycarbonate membrane immobilization process, and their performance for heavy metals and toxic organic compounds acute toxicity determination were studied. The results showed that when E. coli was in logarithmic and stationary phase, the CellSense biosensor with E. coli showed good performance in heavy metal ions and organic pollutants acute toxicity analysis, when E. coli was in its decline phase, the stability and sensitivity of the CellSense biosensor was poor. The EC50 values of Hg2+, Cu2+, Zn2+, o-chlorophenol (2-CP) and p-nitrophenol (4-NP) detected by CellSense biosensor with E. coli were 0.6, 3.1, 5.8, 180 and 94 microg/mL, respectively. The immobilized E. coli electrodes could still suit for acute toxicity assessment after 2 months storage at 4 degrees C.

Nanoparticles with Embedded Porphyrin Photosensitizers for Photooxidation Reactions and Continuous Oxygen Sensing.

PubMed

Kubát, Pavel; Henke, Petr; Berzediová, Veronika; Štěpánek, Miroslav; Lang, Kamil; Mosinger, Jiří

2017-10-18

We report the synthesis and characterization of sulfonated polystyrene nanoparticles (average diameter 30 ± 14 nm) with encapsulated 5,10,15,20-tetraphenylporphyrin or ionically entangled tetracationic 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin, their photooxidation properties, and the application of singlet oxygen-sensitized delayed fluorescence (SODF) in oxygen sensing. Both types of nanoparticles effectively photogenerated singlet oxygen, O 2 ( 1 Δ g ). The O 2 ( 1 Δ g ) phosphorescence, transient absorption of the porphyrin triplet states, and SODF signals were monitored using time-resolved spectroscopic techniques. The SODF intensity depended on the concentration of the porphyrin photosensitizer and dissolved oxygen and on the temperature. After an initial period (a few microseconds), the kinetics of the SODF process can be approximated as a monoexponential function, and the apparent SODF lifetimes can be correlated with the oxygen concentration. The oxygen sensing based on SODF allowed measurement of the dissolved oxygen in aqueous media in the broad range of oxygen concentrations (0.2-38 mg L -1 ). The ability of both types of nanoparticles to photooxidize external substrates was predicted by the SODF measurements and proven by chemical tests. The relative photooxidation efficacy was highest at a low porphyrin concentration, as indicated by the highest fluorescence quantum yield (Φ F ), and it corresponds with negligible inner filter and self-quenching effects. The photooxidation abilities were sensitive to the influence of temperature on the diffusion and solubility of oxygen in both polystyrene and water media and to the rate constant of the O 2 ( 1 Δ g ) reaction with a substrate. Due to their efficient photogeneration of cytotoxic O 2 ( 1 Δ g ) at physiological temperatures and their oxygen sensing via SODF, both types of nanoparticles are promising candidates for biomedical applications.

Oxygen Sensing with Perfluorocarbon-Loaded Ultraporous Mesostructured Silica Nanoparticles.

PubMed

Lee, Amani L; Gee, Clifford T; Weegman, Bradley P; Einstein, Samuel A; Juelfs, Adam R; Ring, Hattie L; Hurley, Katie R; Egger, Sam M; Swindlehurst, Garrett; Garwood, Michael; Pomerantz, William C K; Haynes, Christy L

2017-06-27

Oxygen homeostasis is important in the regulation of biological function. Disease progression can be monitored by measuring oxygen levels, thus producing information for the design of therapeutic treatments. Noninvasive measurements of tissue oxygenation require the development of tools with minimal adverse effects and facile detection of features of interest. Fluorine magnetic resonance imaging ( 19 F MRI) exploits the intrinsic properties of perfluorocarbon (PFC) liquids for anatomical imaging, cell tracking, and oxygen sensing. However, the highly hydrophobic and lipophobic properties of perfluorocarbons require the formation of emulsions for biological studies, though stabilizing these emulsions has been challenging. To enhance the stability and biological loading of perfluorocarbons, one option is to incorporate perfluorocarbon liquids into the internal space of biocompatible mesoporous silica nanoparticles. Here, we developed perfluorocarbon-loaded ultraporous mesostructured silica nanoparticles (PERFUMNs) as 19 F MRI detectable oxygen-sensing probes. Ultraporous mesostructured silica nanoparticles (UMNs) have large internal cavities (average = 1.8 cm 3 g -1 ), facilitating an average 17% loading efficiency of PFCs, meeting the threshold fluorine concentrations needed for imaging studies. Perfluoro-15-crown-5-ether PERFUMNs have the highest equivalent nuclei per PFC molecule and a spin-lattice (T 1 ) relaxation-based oxygen sensitivity of 0.0032 mmHg -1 s -1 at 16.4 T. The option of loading PFCs after synthesizing UMNs, rather than traditional in situ core-shell syntheses, allows for use of a broad range of PFC liquids from a single material. The biocompatible and tunable chemistry of UMNs combined with the intrinsic properties of PFCs makes PERFUMNs a MRI sensor with potential for anatomical imaging, cell tracking, and metabolic spectroscopy with improved stability.

Evolution and physiology of neural oxygen sensing

PubMed Central

Costa, Kauê M.; Accorsi-Mendonça, Daniela; Moraes, Davi J. A.; Machado, Benedito H.

2014-01-01

Major evolutionary trends in animal physiology have been heavily influenced by atmospheric O2 levels. Amongst other important factors, the increase in atmospheric O2 which occurred in the Pre-Cambrian and the development of aerobic respiration beckoned the evolution of animal organ systems that were dedicated to the absorption and transportation of O2, e.g., the respiratory and cardiovascular systems of vertebrates. Global variations of O2 levels in post-Cambrian periods have also been correlated with evolutionary changes in animal physiology, especially cardiorespiratory function. Oxygen transportation systems are, in our view, ultimately controlled by the brain related mechanisms, which senses changes in O2 availability and regulates autonomic and respiratory responses that ensure the survival of the organism in the face of hypoxic challenges. In vertebrates, the major sensorial system for oxygen sensing and responding to hypoxia is the peripheral chemoreflex neuronal pathways, which includes the oxygen chemosensitive glomus cells and several brainstem regions involved in the autonomic regulation of the cardiovascular system and respiratory control. In this review we discuss the concept that regulating O2 homeostasis was one of the primordial roles of the nervous system. We also review the physiology of the peripheral chemoreflex, focusing on the integrative repercussions of chemoreflex activation and the evolutionary importance of this system, which is essential for the survival of complex organisms such as vertebrates. The contribution of hypoxia and peripheral chemoreflex for the development of diseases associated to the cardiovascular and respiratory systems is also discussed in an evolutionary context. PMID:25161625

Acute effect of glucose on cerebral blood flow, blood oxygenation, and oxidative metabolism.

PubMed

Xu, Feng; Liu, Peiying; Pascual, Juan M; Xiao, Guanghua; Huang, Hao; Lu, Hanzhang

2015-02-01

While it is known that specific nuclei of the brain, for example hypothalamus, contain glucose-sensing neurons thus their activity is affected by blood glucose level, the effect of glucose modulation on whole-brain metabolism is not completely understood. Several recent reports have elucidated the long-term impact of caloric restriction on the brain, showing that animals under caloric restriction had enhanced rate of tricarboxylic acid cycle (TCA) cycle flux accompanied by extended life span. However, acute effect of postprandial blood glucose increase has not been addressed in detail, partly due to a scarcity and complexity of measurement techniques. In this study, using a recently developed noninvasive MR technique, we measured dynamic changes in global cerebral metabolic rate of O2 (CMRO2 ) following a 50 g glucose ingestion (N = 10). A time dependent decrease in CMRO2 was observed, which was accompanied by a reduction in oxygen extraction fraction (OEF) with unaltered cerebral blood flow (CBF). At 40 min post-ingestion, the amount of CMRO2 reduction was 7.8 ± 1.6%. A control study without glucose ingestion was performed (N = 10), which revealed no changes in CMRO2 , CBF, or OEF, suggesting that the observations in the glucose study was not due to subject drowsiness or fatigue after staying inside the scanner. These findings suggest that ingestion of glucose may alter the rate of cerebral metabolism of oxygen in an acute setting. © 2014 Wiley Periodicals, Inc.

Thoracic Society of Australia and New Zealand oxygen guidelines for acute oxygen use in adults: ‘Swimming between the flags’*

PubMed Central

Beasley, Richard; Chien, Jimmy; Douglas, James; Eastlake, Leonie; Farah, Claude; King, Gregory; Moore, Rosemary; Pilcher, Janine; Richards, Michael; Smith, Sheree; Walters, Haydn

2015-01-01

The purpose of the Thoracic Society of Australia and New Zealand guidelines is to provide simple, practical evidence-based recommendations for the acute use of oxygen in adults in clinical practice. The intended users are all health professionals responsible for the administration and/or monitoring of oxygen therapy in the management of acute medical patients in the community and hospital settings (excluding perioperative and intensive care patients), those responsible for the training of such health professionals, and both public and private health care organizations that deliver oxygen therapy. PMID:26486092

Local oxygen therapy for treating acute necrotizing periodontal disease in smokers.

PubMed

Gaggl, Alexander J; Rainer, Heribert; Grund, Eveline; Chiari, Friedrich M

2006-01-01

The main aim of treatment for acute necrotizing periodontal disease is fast and effective reduction of anaerobic destructive microorganisms to avoid periodontal damage. The effect of adjunctive local oxygen therapy in the treatment of necrotizing periodontal disease was examined in this study. Thirty patients with acute necrotizing periodontal disease were treated with the systemic antibiotics amoxicillin, clavulanic acid, and metronidazole. In 15 out of 30 patients, adjunctive local oxygen therapy was administered. The patients were followed from the first to 10th day of treatment with clinical and bacteriological examinations. The clinical examination registered gingival bleeding, periodontal probing depth, and attachment loss; to follow up microbiological colonization of the periodontal sulcus, five representative bacteria were registered by a semiquantitative DNA polymerase chain reaction test. In both groups of patients, colonization with Prevotella intermedia, Tannerella forsythensis, and Treponema denticola was initially positive. None of these three microorganisms were completely eradicated in any of the patients in the group without oxygen therapy within the first 10 days of treatment. In the group with adjunctive oxygen therapy, all patients either showed a reduction in or complete eradication of the microorganisms, resulting in more rapid clinical restitution with less periodontal destruction. Adjunctive oxygen therapy results in early eradication of pathogenic anaerobic microorganisms in cases of acute necrotizing periodontal disease. The damage to periodontal tissue is reduced.

Fluorescent microparticles for sensing cell microenvironment oxygen levels within 3D scaffolds

PubMed Central

Acosta, Miguel A.; Ymele-Leki, Patrick; Kostov, Yordan V.; Leach, Jennie B.

2010-01-01

We present the development and characterization of fluorescent oxygen-sensing microparticles designed for measuring oxygen concentration in microenvironments existing within standard cell culture and transparent three-dimensional (3D) cell scaffolds. The microparticle synthesis employs poly(dimethylsiloxane) to encapsulate silica gel particles bound with an oxygen-sensitive luminophore as well as a reference or normalization fluorophore that is insensitive to oxygen. We developed a rapid, automated and non-invasive sensor analysis method based on fluorescence microscopy to measure oxygen concentration in a hydrogel scaffold. We demonstrate that the microparticles are non-cytotoxic and that their response is comparable to that of a traditional dissolved oxygen meter. Microparticle size (5–40 μm) was selected for microscale-mapping of oxygen concentration to allow measurements local to individual cells. Two methods of calibration were evaluated and revealed that the sensor system enables characterization of a range of hypoxic to hyperoxic conditions relevant to cell and tissue biology (i.e., pO2 10–160 mm Hg). The calibration analysis also revealed that the microparticles have a high fraction of quenched luminophore (0.90 ± 0.02), indicating that the reported approach provides significant advantages for sensor performance. This study thus reports a versatile oxygen-sensing technology that enables future correlations of local oxygen concentration with individual cell response in cultured engineered tissues. PMID:19285719

Fluorescent microparticles for sensing cell microenvironment oxygen levels within 3D scaffolds.

PubMed

Acosta, Miguel A; Ymele-Leki, Patrick; Kostov, Yordan V; Leach, Jennie B

2009-06-01

We present the development and characterization of fluorescent oxygen-sensing microparticles designed for measuring oxygen concentration in microenvironments existing within standard cell culture and transparent three-dimensional (3D) cell scaffolds. The microparticle synthesis employs poly(dimethylsiloxane) to encapsulate silica gel particles bound with an oxygen-sensitive luminophore as well as a reference or normalization fluorophore that is insensitive to oxygen. We developed a rapid, automated and non-invasive sensor analysis method based on fluorescence microscopy to measure oxygen concentration in a hydrogel scaffold. We demonstrate that the microparticles are non-cytotoxic and that their response is comparable to that of a traditional dissolved oxygen meter. Microparticle size (5-40 microm) was selected for microscale-mapping of oxygen concentration to allow measurements local to individual cells. Two methods of calibration were evaluated and revealed that the sensor system enables characterization of a range of hypoxic to hyperoxic conditions relevant to cell and tissue biology (i.e., pO(2) 10-160 mmHg). The calibration analysis also revealed that the microparticles have a high fraction of quenched luminophore (0.90+/-0.02), indicating that the reported approach provides significant advantages for sensor performance. This study thus reports a versatile oxygen-sensing technology that enables future correlations of local oxygen concentration with individual cell response in cultured engineered tissues.

Classifying Acute Respiratory Distress Syndrome Severity: Correcting the Arterial Oxygen Partial Pressure to Fractional Inspired Oxygen at Altitude.

PubMed

Pérez-Padilla, Rogelio; Hernández-Cárdenas, Carmen Margarita; Lugo-Goytia, Gustavo

2016-01-01

In the well-known Berlin definition of acute respiratory distress syndrome (ARDS), there is a recommended adjustment for arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FIO2) at altitude, but without a reference as to how it was derived.

Efficient fluorescence "turn-on" sensing of dissolved oxygen by electrochemical switching.

PubMed

Shin, Ik-Soo; Hirsch, Thomas; Ehrl, Benno; Jang, Dong-Hak; Wolfbeis, Otto S; Hong, Jong-In

2012-11-06

We report on a novel method for sensing oxygen that is based on the use of a perylene diimide dye (1) which is electrochemically reduced to its nonfluorescent dianion form (1(2-)). In the presence of oxygen, the dianion is oxidized to its initial form via an electron-transfer reaction with oxygen upon which fluorescence is recovered. As a result, the fluorescence intensity of the dianion solution increases upon the addition of oxygen gas. Results demonstrate that high sensitivity is obtained, and the emission intensity shows a linear correlation with oxygen content (0.0-4.0% v/v) at ambient barometric pressure. In addition, using electrochemical reduction, oxygen determination becomes regenerative, and no significant degradation is observed over several turnovers. The limit of detection is 0.4% oxygen in argon gas.

Spatiotemporal Oxygen Sensing Using Dual Emissive Boron Dye–Polylactide Nanofibers

PubMed Central

2015-01-01

Oxygenation in tissue scaffolds continues to be a limiting factor in regenerative medicine despite efforts to induce neovascularization or to use oxygen-generating materials. Unfortunately, many established methods to measure oxygen concentration, such as using electrodes, require mechanical disturbance of the tissue structure. To address the need for scaffold-based oxygen concentration monitoring, a single-component, self-referenced oxygen sensor was made into nanofibers. Electrospinning process parameters were tuned to produce a biomaterial scaffold with specific morphological features. The ratio of an oxygen sensitive phosphorescence signal to an oxygen insensitive fluorescence signal was calculated at each image pixel to determine an oxygenation value. A single component boron dye–polymer conjugate was chosen for additional investigation due to improved resistance to degradation in aqueous media compared to a boron dye polymer blend. Standardization curves show that in fully supplemented media, the fibers are responsive to dissolved oxygen concentrations less than 15 ppm. Spatial (millimeters) and temporal (minutes) ratiometric gradients were observed in vitro radiating outward from the center of a dense adherent cell grouping on scaffolds. Sensor activation in ischemia and cell transplant models in vivo show oxygenation decreases on the scale of minutes. The nanofiber construct offers a robust approach to biomaterial scaffold oxygen sensing. PMID:25426706

Oxygen therapy for acute myocardial infarction.

PubMed

Cabello, Juan B; Burls, Amanda; Emparanza, José I; Bayliss, Susan E; Quinn, Tom

2016-12-19

Oxygen (O 2 ) is widely used in people with acute myocardial infarction (AMI). Previous systematic reviews concluded that there was insufficient evidence to know whether oxygen reduced, increased or had no effect on heart ischaemia or infarct size. Our first Cochrane review in 2010 also concluded there was insufficient evidence to know whether oxygen should be used. Since 2010, the lack of evidence to support this widely used intervention has attracted considerable attention, prompting further trials of oxygen therapy in myocardial infarction patients. It is thus important to update this Cochrane review. To assess the effects of routine use of inhaled oxygen for acute myocardial infarction (AMI). We searched the following bibliographic databases on 6 June 2015: the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE (OVID), Embase (OVID), CINAHL (EBSCO) and Web of Science (Thomson Reuters). LILACS (Latin American and Caribbean Health Sciences Literature) was last searched in September 2016. We also contacted experts to identify eligible studies. We applied no language restrictions. Randomised controlled trials in people with suspected or proven AMI (ST-segment elevation myocardial infarction (STEMI) or non-STEMI) within 24 hours after onset, in which the intervention was inhaled oxygen (at normal pressure) compared to air, regardless of co-therapies provided to participants in both arms of the trial. Two authors independently reviewed the titles and abstracts of identified studies to see if they met the inclusion criteria and independently undertook the data extraction. We assessed the quality of studies and the risk of bias according to guidance in the Cochrane Handbook for Systematic Reviews of Interventions. The primary outcome was death. The measure of effect used was the risk ratio (RR) with a 95% confidence interval (CI). We used the GRADE approach to evaluate the quality of the evidence and the GRADE profiler (GRADEpro

Oxygen scrubbing and sensing in plant growth chambers using solid oxide electrolyzers

NASA Technical Reports Server (NTRS)

Sridhar, K. R.; MacElroy, Robert D.

1997-01-01

The maintenance of optimal levels of oxygen in the gaseous environment of a plant growth chamber during light and dark periods is an essential criterion for the correct growth of plants. The use of solid oxide electrolyzers to control the oxygen levels by removing the excess gaseous oxygen during periods of illumination and full-scale photosynthesis is described. A part of the oxygen removed can be stored and supplied back to the plants during dark periods. The excess oxygen can be used by the crew. The electrolizer can be additionally used in its open circuit mode, to sense the oxygen concentrations in the plant chamber. The solid oxide electrolysis process is described.

A Microfluidic Device for Continuous Sensing of Systemic Acute Toxicants in Drinking Water

PubMed Central

Zhao, Xinyan; Dong, Tao

2013-01-01

A bioluminescent-cell-based microfluidic device for sensing toxicants in drinking water was designed and fabricated. The system employed Vibrio fischeri cells as broad-spectrum sensors to monitor potential systemic cell toxicants in water, such as heavy metal ions and phenol. Specifically, the chip was designed for continuous detection. The chip design included two counter-flow micromixers, a T-junction droplet generator and six spiral microchannels. The cell suspension and water sample were introduced into the micromixers and dispersed into droplets in the air flow. This guaranteed sufficient oxygen supply for the cell sensors. Copper (Cu2+), zinc (Zn2+), potassium dichromate and 3,5-dichlorophenol were selected as typical toxicants to validate the sensing system. Preliminary tests verified that the system was an effective screening tool for acute toxicants although it could not recognize or quantify specific toxicants. A distinct non-linear relationship was observed between the zinc ion concentration and the Relative Luminescence Units (RLU) obtained during testing. Thus, the concentration of simple toxic chemicals in water can be roughly estimated by this system. The proposed device shows great promise for an early warning system for water safety. PMID:24300075

Effects of acute hypoxic exposure on oxygen affinity of human red blood cells.

PubMed

Chowdhury, Aniket; Dasgupta, Raktim

2017-01-20

Adaptation of red blood cells subjected to acute hypoxia, crucial for managing high altitude syndrome and pulmonary diseases, has been investigated. For this, red blood cells were exposed to the acute hypoxic condition by purging nitrogen over increasing time periods from 15 to 60 min and thereafter equilibrated with atmospheric oxygen for 10 min. Raman spectra of these red blood cells were then recorded and analyzed to look for changes in the level of oxygenation compared to unexposed cells. A decreasing oxygen affinity for the cells was observed with increasing time of exposure to the hypoxic condition. This change in oxygen affinity for the red blood cells may result from metabolic adjustment of the cells under the hypoxic condition to promote increased concentration of intracellular 2, 3-diphosphoglycerate.

A rhenium complex doped in a silica molecular sieve for molecular oxygen sensing: Construction and characterization.

PubMed

Yang, Xiaozhou; Li, Yanxiao

2016-01-15

This paper reported a diamine ligand and its Re(I) complex for potential application in oxygen sensing. The novelty of this diamine ligand localized at its increased conjugation chain which had a typical electron-withdrawing group of 1,3,4-oxadiazole. Electronic distribution of excited electrons and their lifetime were supposed to be increased, favoring oxygen sensing collision. This hypothesis was confirmed by single crystal analysis, theoretical calculation and photophysical measurement. It was found that this Re(I) complex had a long-lived emission peaking at 545 nm, favoring sensing application. By doping this complex into a silica matrix MCM-41, oxygen sensing performance and mechanism of the resulting composites were discussed in detail. Non-linear Stern-Volmer working curves were observed with maximum sensitivity of 5.54 and short response time of ~6 s. Copyright © 2015 Elsevier B.V. All rights reserved.

Cellular Oxygen and Nutrient Sensing in Microgravity Using Time-Resolved Fluorescence Microscopy

NASA Technical Reports Server (NTRS)

Szmacinski, Henryk

2003-01-01

Oxygen and nutrient sensing is fundamental to the understanding of cell growth and metabolism. This requires identification of optical probes and suitable detection technology without complex calibration procedures. Under this project Microcosm developed an experimental technique that allows for simultaneous imaging of intra- and inter-cellular events. The technique consists of frequency-domain Fluorescence Lifetime Imaging Microscopy (FLIM), a set of identified oxygen and pH probes, and methods for fabrication of microsensors. Specifications for electronic and optical components of FLIM instrumentation are provided. Hardware and software were developed for data acquisition and analysis. Principles, procedures, and representative images are demonstrated. Suitable lifetime sensitive oxygen, pH, and glucose probes for intra- and extra-cellular measurements of analyte concentrations have been identified and tested. Lifetime sensing and imaging have been performed using PBS buffer, culture media, and yeast cells as a model systems. Spectral specifications, calibration curves, and probes availability are also provided in the report.

Reversed oxygen sensing using colloidal quantum wells towards highly emissive photoresponsive varnishes

PubMed Central

Lorenzon, Monica; Christodoulou, Sotirios; Vaccaro, Gianfranco; Pedrini, Jacopo; Meinardi, Francesco; Moreels, Iwan; Brovelli, Sergio

2015-01-01

Colloidal quantum wells combine the advantages of size-tunable electronic properties with vast reactive surfaces that could allow one to realize highly emissive luminescent-sensing varnishes capable of detecting chemical agents through their reversible emission response, with great potential impact on life sciences, environmental monitoring, defence and aerospace engineering. Here we combine spectroelectrochemical measurements and spectroscopic studies in a controlled atmosphere to demonstrate the ‘reversed oxygen-sensing’ capability of CdSe colloidal quantum wells, that is, the exposure to oxygen reversibly increases their luminescence efficiency. Spectroelectrochemical experiments allow us to directly relate the sensing response to the occupancy of surface states. Magneto-optical measurements demonstrate that, under vacuum, heterostructured CdSe/CdS colloidal quantum wells stabilize in their negative trion state. The high starting emission efficiency provides a possible means to enhance the oxygen sensitivity by partially de-passivating the particle surfaces, thereby enhancing the density of unsaturated sites with a minimal cost in term of luminescence losses. PMID:25910499

Video monitoring of oxygen saturation during controlled episodes of acute hypoxia.

PubMed

Addison, Paul S; Foo, David M H; Jacquel, Dominique; Borg, Ulf

2016-08-01

A method for extracting video photoplethysmographic information from an RGB video stream is tested on data acquired during a porcine model of acute hypoxia. Cardiac pulsatile information was extracted from the acquired signals and processed to determine a continuously reported oxygen saturation (SvidO2). A high degree of correlation was found to exist between the video and a reference from a pulse oximeter. The calculated mean bias and accuracy across all eight desaturation episodes were -0.03% (range: -0.21% to 0.24%) and accuracy 4.90% (range: 3.80% to 6.19%) respectively. The results support the hypothesis that oxygen saturation trending can be evaluated accurately from a video system during acute hypoxia.

Acute hypoxia in a simulated high-altitude airdrop scenario due to oxygen system failure.

PubMed

Ottestad, William; Hansen, Tor Are; Pradhan, Gaurav; Stepanek, Jan; Høiseth, Lars Øivind; Kåsin, Jan Ivar

2017-12-01

High-Altitude High Opening (HAHO) is a military operational procedure in which parachute jumps are performed at high altitude requiring supplemental oxygen, putting personnel at risk of acute hypoxia in the event of oxygen equipment failure. This study was initiated by the Norwegian Army to evaluate potential outcomes during failure of oxygen supply, and to explore physiology during acute severe hypobaric hypoxia. A simulated HAHO without supplemental oxygen was carried out in a hypobaric chamber with decompression to 30,000 ft (9,144 m) and then recompression to ground level with a descent rate of 1,000 ft/min (305 m/min). Nine subjects were studied. Repeated arterial blood gas samples were drawn throughout the entire hypoxic exposure. Additionally, pulse oximetry, cerebral oximetry, and hemodynamic variables were monitored. Desaturation evolved rapidly and the arterial oxygen tensions are among the lowest ever reported in volunteers during acute hypoxia. Pa O 2 decreased from baseline 18.4 (17.3-19.1) kPa, 138.0 (133.5-143.3) mmHg, to a minimum value of 3.3 (2.9-3.7) kPa, 24.8 (21.6-27.8) mmHg, after 180 (60-210) s, [median (range)], N = 9. Hyperventilation with ensuing hypocapnia was associated with both increased arterial oxygen saturation and cerebral oximetry values, and potentially improved tolerance to severe hypoxia. One subject had a sharp drop in heart rate and cardiac index and lost consciousness 4 min into the hypoxic exposure. A simulated high-altitude airdrop scenario without supplemental oxygen results in extreme hypoxemia and may result in loss of consciousness in some individuals. NEW & NOTEWORTHY This is the first study to investigate physiology and clinical outcome of oxygen system failure in a simulated HAHO scenario. The acquired knowledge is of great value to make valid risk-benefit analyses during HAHO training or operations. The arterial oxygen tensions reported in this hypobaric chamber study are among the lowest ever reported during acute

Noninvasive Optical Monitoring of Spinal Cord Hemodynamics and Oxygenation after Acute Spinal Cord Injury

DTIC Science & Technology

2017-09-01

oxygen delivery and oxygen consumption . The oxygen portion of the Oxylite probe emits short pulses of blue LED light resulting in a fluorescent...Award Number: W81XWH-16-1-0602 TITLE: Noninvasive Optical Monitoring of Spinal Cord Hemodynamics and Oxygenation after Acute Spinal Cord Injury...COVERED 1 Sep 2016 - 31 Aug 2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Noninvasive Optical Monitoring of Spinal Cord Hemodynamics and Oxygenation

Luminescent sensing and imaging of oxygen: fierce competition to the Clark electrode.

PubMed

Wolfbeis, Otto S

2015-08-01

Luminescence-based sensing schemes for oxygen have experienced a fast growth and are in the process of replacing the Clark electrode in many fields. Unlike electrodes, sensing is not limited to point measurements via fiber optic microsensors, but includes additional features such as planar sensing, imaging, and intracellular assays using nanosized sensor particles. In this essay, I review and discuss the essentials of (i) common solid-state sensor approaches based on the use of luminescent indicator dyes and host polymers; (ii) fiber optic and planar sensing schemes; (iii) nanoparticle-based intracellular sensing; and (iv) common spectroscopies. Optical sensors are also capable of multiple simultaneous sensing (such as O2 and temperature). Sensors for O2 are produced nowadays in large quantities in industry. Fields of application include sensing of O2 in plant and animal physiology, in clinical chemistry, in marine sciences, in the chemical industry and in process biotechnology. © 2015 The Author. Bioessays published by WILEY Periodicals, Inc.

Luminescent sensing and imaging of oxygen: Fierce competition to the Clark electrode

PubMed Central

2015-01-01

Luminescence‐based sensing schemes for oxygen have experienced a fast growth and are in the process of replacing the Clark electrode in many fields. Unlike electrodes, sensing is not limited to point measurements via fiber optic microsensors, but includes additional features such as planar sensing, imaging, and intracellular assays using nanosized sensor particles. In this essay, I review and discuss the essentials of (i) common solid‐state sensor approaches based on the use of luminescent indicator dyes and host polymers; (ii) fiber optic and planar sensing schemes; (iii) nanoparticle‐based intracellular sensing; and (iv) common spectroscopies. Optical sensors are also capable of multiple simultaneous sensing (such as O2 and temperature). Sensors for O2 are produced nowadays in large quantities in industry. Fields of application include sensing of O2 in plant and animal physiology, in clinical chemistry, in marine sciences, in the chemical industry and in process biotechnology. PMID:26113255

MEDEX2015: Greater Sea-Level Fitness Is Associated with Lower Sense of Effort During Himalayan Trekking Without Worse Acute Mountain Sickness.

PubMed

Rossetti, Gabriella M K; Macdonald, Jamie H; Smith, Matthew; Jackson, Anna R; Callender, Nigel; Newcombe, Hannah K; Storey, Heather M; Willis, Sebastian; van den Beukel, Jojanneke; Woodward, Jonathan; Pollard, James; Wood, Benjamin; Newton, Victoria; Virian, Jana; Haswell, Owen; Oliver, Samuel J

2017-06-01

Rossetti, Gabriella M.K., Jamie H. Macdonald, Matthew Smith, Anna R. Jackson, Nigel Callender, Hannah K. Newcombe, Heather M. Storey, Sebastian Willis, Jojanneke van den Beukel, Jonathan Woodward, James Pollard, Benjamin Wood, Victoria Newton, Jana Virian, Owen Haswell, and Samuel J. Oliver. MEDEX2015: Greater sea-level fitness is associated with lower sense of effort during Himalayan trekking without worse acute mountain sickness. High Alt Med Biol. 18:152-162, 2017.-This study examined the complex relationships of fitness and hypoxic sensitivity with submaximal exercise responses and acute mountain sickness (AMS) at altitude. Determining these relationships is necessary before fitness or hypoxic sensitivity tests can be recommended to appraise individuals' readiness for altitude. Forty-four trekkers (26 men; 18 women; 20-67 years) completed a loaded walking test and a fitness questionnaire in normoxia to measure and estimate sea-level maximal aerobic capacity (maximum oxygen consumption [[Formula: see text]O 2max ]), respectively. Participants also completed a hypoxic exercise test to determine hypoxic sensitivity (cardiac, ventilatory, and arterial oxygen saturation responses to acute hypoxia, fraction of inspired oxygen [Fio 2 ] = 0.112). One month later, all participants completed a 3-week trek to 5085 m with the same ascent profile. On ascent to 5085 m, ratings of perceived exertion (RPE ascent ), fatigue by Brunel Mood Scale, and AMS were recorded daily. At 5085 m, RPE during a fixed workload step test (RPE fixed ) and step rate during perceptually regulated exercise (STEP RPE35 ) were recorded. Greater sea-level [Formula: see text]O 2max was associated with, and predicted, lower sense of effort (RPE ascent ; r = -0.43; p < 0.001; RPE fixed ; r = -0.69; p < 0.001) and higher step rate (STEP RPE35 ; r = 0.62; p < 0.01), but not worse AMS (r = 0.13; p = 0.4) or arterial oxygen desaturation (r = 0.07; p = 0

Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics

PubMed Central

Liu, Jianqiao; Gao, Yinglin; Wu, Xu; Jin, Guohua; Zhai, Zhaoxia; Liu, Huan

2017-01-01

The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width. PMID:28796167

Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics.

PubMed

Liu, Jianqiao; Gao, Yinglin; Wu, Xu; Jin, Guohua; Zhai, Zhaoxia; Liu, Huan

2017-08-10

The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width.

High sensitivity and accuracy dissolved oxygen (DO) detection by using PtOEP/poly(MMA-co-TFEMA) sensing film

NASA Astrophysics Data System (ADS)

Zhang, Ke; Zhang, Honglin; Wang, Ying; Tian, Yanqing; Zhao, Jiupeng; Li, Yao

2017-01-01

Fluorinated acrylate polymer has received great interest in recent years due to its extraordinary characteristics such as high oxygen permeability, good stability, low surface energy and refractive index. In this work, platinum octaethylporphyrin/poly(methylmethacrylate-co-trifluoroethyl methacrylate) (PtOEP/poly(MMA-co-TFEMA)) oxygen sensing film was prepared by the immobilizing of PtOEP in a poly(MMA-co-TFEMA) matrix and the technological readiness of optical properties was established based on the principle of luminescence quenching. It was found that the oxygen-sensing performance could be improved by optimizing the monomer ratio (MMA/TFEMA = 1:1), tributylphosphate(TBP, 0.05 mL) and PtOEP (5 μg) content. Under this condition, the maximum quenching ratio I0/I100 of the oxygen sensing film is obtained to be about 8.16, Stern-Volmer equation is I0/I = 1.003 + 2.663[O2] (R2 = 0.999), exhibiting a linear relationship, good photo-stability, high sensitivity and accuracy. Finally, the synthesized PtOEP/poly(MMA-co-TFEMA) sensing film was used for DO detection in different water samples.

Oxygen Sensing Difluoroboron β-Diketonate Polylactide Materials with Tunable Dynamic Ranges for Wound Imaging.

PubMed

DeRosa, Christopher A; Seaman, Scott A; Mathew, Alexander S; Gorick, Catherine M; Fan, Ziyi; Demas, James N; Peirce, Shayn M; Fraser, Cassandra L

2016-11-23

Difluoroboron β-diketonate poly(lactic acid) materials exhibit both fluorescence (F) and oxygen sensitive room-temperature phosphorescence (RTP). Introduction of halide heavy atoms (Br and I) is an effective strategy to control the oxygen sensitivity in these materials. A series of naphthyl-phenyl (nbm) dye derivatives with hydrogen, bromide and iodide substituents were prepared for comparison. As nanoparticles, the hydrogen derivative was hypersensitive to oxygen (0-0.3%), while the bromide analogue was suited for hypoxia detection (0-3% O 2 ). The iodo derivative, BF 2 nbm(I)PLA, showed excellent F to RTP peak separation and an 0-100% oxygen sensitivity range unprecedented for metal-free RTP emitting materials. Due to the dual emission and unconventionally long RTP lifetimes of these O 2 sensing materials, a portable, cost-effective camera was used to quantify oxygen levels via lifetime and red/green/blue (RGB) ratiometry. The hypersensitive H dye was well matched to lifetime detection, simultaneous lifetime and ratiometric imaging was possible for the bromide analogue, whereas the iodide material, with intense RTP emission and a shorter lifetime, was suited for RGB ratiometry. To demonstrate the prospects of this camera/material design combination for bioimaging, iodide boron dye-PLA nanoparticles were applied to a murine wound model to detect oxygen levels. Surprisingly, wound oxygen imaging was achieved without covering (i.e. without isolating from ambient conditions, air). Additionally, would healing was monitored via wound size reduction and associated oxygen recovery, from hypoxic to normoxic. These single-component materials provide a simple tunable platform for biological oxygen sensing that can be deployed to spatially resolve oxygen in a variety of environments.

Neuroprotection of hyperbaric oxygen therapy in sub-acute traumatic brain injury: not by immediately improving cerebral oxygen saturation and oxygen partial pressure.

PubMed

Zhou, Bao-Chun; Liu, Li-Jun; Liu, Bing

2016-09-01

Although hyperbaric oxygen (HBO) therapy can promote the recovery of neural function in patients who have suffered traumatic brain injury (TBI), the underlying mechanism is unclear. We hypothesized that hyperbaric oxygen treatment plays a neuroprotective role in TBI by increasing regional transcranial oxygen saturation (rSO 2 ) and oxygen partial pressure (PaO 2 ). To test this idea, we compared two groups: a control group with 20 healthy people and a treatment group with 40 TBI patients. The 40 patients were given 100% oxygen of HBO for 90 minutes. Changes in rSO 2 were measured. The controls were also examined for rSO 2 and PaO 2 , but received no treatment. rSO 2 levels in the patients did not differ significantly after treatment, but levels before and after treatment were significantly lower than those in the control group. PaO 2 levels were significantly decreased after the 30-minute HBO treatment. Our findings suggest that there is a disorder of oxygen metabolism in patients with sub-acute TBI. HBO does not immediately affect cerebral oxygen metabolism, and the underlying mechanism still needs to be studied in depth.

High sensitivity and accuracy dissolved oxygen (DO) detection by using PtOEP/poly(MMA-co-TFEMA) sensing film.

PubMed

Zhang, Ke; Zhang, Honglin; Wang, Ying; Tian, Yanqing; Zhao, Jiupeng; Li, Yao

2017-01-05

Fluorinated acrylate polymer has received great interest in recent years due to its extraordinary characteristics such as high oxygen permeability, good stability, low surface energy and refractive index. In this work, platinum octaethylporphyrin/poly(methylmethacrylate-co-trifluoroethyl methacrylate) (PtOEP/poly(MMA-co-TFEMA)) oxygen sensing film was prepared by the immobilizing of PtOEP in a poly(MMA-co-TFEMA) matrix and the technological readiness of optical properties was established based on the principle of luminescence quenching. It was found that the oxygen-sensing performance could be improved by optimizing the monomer ratio (MMA/TFEMA=1:1), tributylphosphate(TBP, 0.05mL) and PtOEP (5μg) content. Under this condition, the maximum quenching ratio I0/I100 of the oxygen sensing film is obtained to be about 8.16, Stern-Volmer equation is I0/I=1.003+2.663[O2] (R(2)=0.999), exhibiting a linear relationship, good photo-stability, high sensitivity and accuracy. Finally, the synthesized PtOEP/poly(MMA-co-TFEMA) sensing film was used for DO detection in different water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Regulation of Carotid Body Oxygen Sensing by Hypoxia-Inducible Factors

PubMed Central

Prabhakar, Nanduri R.; Semenza, Gregg L.

2015-01-01

Oxygen (O2) sensing by the carotid body and its chemosensory reflex is critical for homeostatic regulation of breathing and blood pressure. Carotid body responses to hypoxia are not uniform but instead exhibit remarkable inter-individual variations. The molecular mechanisms underlying variations in carotid body O2 sensing are not known. Hypoxia-inducible factor-1 (HIF-1) and HIF-2 mediate transcriptional responses to hypoxia. This article reviews the emerging evidence that proper expression of the HIF-α isoforms is a key molecular determinant for carotid body O2 sensing. HIF-1α deficiency leads to a blunted carotid body hypoxic response, which is due to increased abundance of HIF-2α, elevated anti-oxidant enzyme activity, and a reduced intracellular redox state. Conversely, HIF-2α deficiency results in augmented carotid body sensitivity to hypoxia, which is due to increased abundance of HIF-1α, elevated pro-oxidant enzyme activity, and an oxidized intracellular redox state. Double heterozygous mice with equally reduced HIF-1α and HIF-2α showed no abnormality in redox state or carotid body O2 sensing. Thus, mutual antagonism between HIF-α isoforms determines the redox state and thereby establishes the set point for hypoxic sensing by the carotid body. PMID:26265380

Remote Sensing of Dissolved Oxygen and Nitrogen in Water Using Raman Spectroscopy

NASA Technical Reports Server (NTRS)

Ganoe, Rene; DeYoung, Russell J.

2013-01-01

The health of an estuarine ecosystem is largely driven by the abundance of dissolved oxygen and nitrogen available for maintenance of plant and animal life. An investigation was conducted to quantify the concentration of dissolved molecular oxygen and nitrogen in water by means of Raman spectroscopy. This technique is proposed for the remote sensing of dissolved oxygen in the Chesapeake Bay, which will be utilized by aircraft in order to survey large areas in real-time. A proof of principle system has been developed and the specifications are being honed to maximize efficiency for the final application. The theoretical criteria of the research, components of the experimental system, and key findings are presented in this report

Uncondensed Graphitic Carbon Nitride on Reduced Graphene Oxide for Oxygen Sensing via a Photoredox Mechanism

DOE PAGES

Ellis, James E.; Sorescu, Dan C.; Burkert, Seth C.; ...

2017-07-24

Melon, a polymeric, uncondensed graphitic carbon nitride with a two-dimensional structure, has been coupled with reduced graphene oxide (rGO) to create an oxygen chemiresistor sensor that is active under UV photoactivation. Oxygen gas is an important sensor target in a variety of areas including industrial safety, combustion process monitoring, as well as environmental and biomedical fields. Because of the intimate electrical interface formed between melon and rGO, charge transfer of photoexcited electrons occurs between the two materials when under UV (λ = 365 nm) irradiation. A photoredox mechanism wherein oxygen is reduced on the rGO surface provides the basis formore » sensing oxygen gas in the concentration range 300–100 000 ppm. The sensor response was found to be logarithmically proportional to oxygen gas concentration. DFT calculations of a melon-oxidized graphene composite found that slight protonation of melon leads to charge accumulation on the rGO layer and a corresponding charge depletion on the melon layer. As a result, this work provides an example of a metal-free system for solid–gas interface sensing via a photoredox mechanism.« less

Uncondensed Graphitic Carbon Nitride on Reduced Graphene Oxide for Oxygen Sensing via a Photoredox Mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellis, James E.; Sorescu, Dan C.; Burkert, Seth C.

Melon, a polymeric, uncondensed graphitic carbon nitride with a two-dimensional structure, has been coupled with reduced graphene oxide (rGO) to create an oxygen chemiresistor sensor that is active under UV photoactivation. Oxygen gas is an important sensor target in a variety of areas including industrial safety, combustion process monitoring, as well as environmental and biomedical fields. Because of the intimate electrical interface formed between melon and rGO, charge transfer of photoexcited electrons occurs between the two materials when under UV (λ = 365 nm) irradiation. A photoredox mechanism wherein oxygen is reduced on the rGO surface provides the basis formore » sensing oxygen gas in the concentration range 300–100 000 ppm. The sensor response was found to be logarithmically proportional to oxygen gas concentration. DFT calculations of a melon-oxidized graphene composite found that slight protonation of melon leads to charge accumulation on the rGO layer and a corresponding charge depletion on the melon layer. As a result, this work provides an example of a metal-free system for solid–gas interface sensing via a photoredox mechanism.« less

ACUTE SENSITIVITY OF JUVENILE SHORTNOSE STURGEON TO LOW DISSOLVED OXYGEN CONCENTRATIONS

EPA Science Inventory

Campbell, Jed G. and Larry R. Goodman. 2004. Acute Sensitivity of Juvenile Shortnose Sturgeon to Low Dissolved Oxygen Concentrations. EPA/600/J-04/175. Trans. Am. Fish. Soc. 133(3):772-776. (ERL,GB 1155).

There is considerable concern that factors such as eutrophication, ...

[Evaluation of different oxygen therapies on therapeutic effects in rats with acute carbon dioxide poisoning].

PubMed

Niu, Ying-mei; Hao, Feng-tong; Xue, Chang-jiang; Xia, Yu-jing; Zhou, Shuo; Lu, Qing-sheng; Liu, Jian-zhong; Zhang, Peng

2011-03-01

To study therapeutic effects by using different oxygen therapies in rats with acute carbon dioxide poisoning, to select the best oxygen therapy technology for patients with acute carbon dioxide poisoning on the spot. Sixty healthy male Sprague-Dawley rats were randomized into normal control group, carbon dioxide exposure group, hyperbaric oxygen treatment group (pressure 2 ATA, FiO(2)100%), high concentration of atmospheric oxygen treatment group (FiO(2)50%), low concentration of atmospheric oxygen treatment group (FiO(2)33%). After treated with different oxygen in rats with acute carbon dioxide poisoning, arterial pH, PO2 and PCO2 of rats were detected, in addition observe pathological changes of lung tissue and brain tissue. The arterial pH (7.31 ± 0.06) and PO2 [(68.50 ± 15.02) mm Hg] of carbon dioxide exposure group were lower than those of control group [pH (7.42 ± 0.02) and PO2 (92.83 ± 8.27) mm Hg], PCO2 [(71.66 ± 12.10) mm Hg] was higher than that of control group [(48.25 ± 2.59) mm Hg] (P < 0.05); the arterial pH (hyperbaric oxygen treatment group 7.37 ± 0.02, high concentration of atmospheric oxygen treatment group 7.39 ± 0.03, low concentration of atmospheric oxygen treatment group 7.38 ± 0.02) and PO2 of oxygen treatment groups [hyperbaric oxygen treatment group, high concentration of atmospheric oxygen treatment group, low concentration of atmospheric oxygen treatment group were (82.25 ± 12.98), (84.75 ± 11.24), (83.75 ± 16.77) mm Hg, respectively] were higher than that of carbon dioxide exposure group, PCO2 [hyperbaric oxygen treatment group, high concentration of atmospheric oxygen treatment group, low concentration of atmospheric oxygen treatment group were (52.25 ± 4.95), (51.75 ± 4.82), (52.66 ± 5.61) mm Hg, respectively] was lower than that of carbon dioxide exposure group (P < 0.05); there was no significant difference of the arterial pH, PO2 and PCO2 between oxygen treatment groups and control group (P > 0.05); there was no

Effect of Routine Low-Dose Oxygen Supplementation on Death and Disability in Adults With Acute Stroke: The Stroke Oxygen Study Randomized Clinical Trial.

PubMed

Roffe, Christine; Nevatte, Tracy; Sim, Julius; Bishop, Jon; Ives, Natalie; Ferdinand, Phillip; Gray, Richard

2017-09-26

Hypoxia is common in the first few days after acute stroke, is frequently intermittent, and is often undetected. Oxygen supplementation could prevent hypoxia and secondary neurological deterioration and thus has the potential to improve recovery. To assess whether routine prophylactic low-dose oxygen therapy was more effective than control oxygen administration in reducing death and disability at 90 days, and if so, whether oxygen given at night only, when hypoxia is most frequent, and oxygen administration is least likely to interfere with rehabilitation, was more effective than continuous supplementation. In this single-blind randomized clinical trial, 8003 adults with acute stroke were enrolled from 136 participating centers in the United Kingdom within 24 hours of hospital admission if they had no clear indications for or contraindications to oxygen treatment (first patient enrolled April 24, 2008; last follow-up January 27, 2015). Participants were randomized 1:1:1 to continuous oxygen for 72 hours (n = 2668), nocturnal oxygen (21:00 to 07:00 hours) for 3 nights (n = 2667), or control (oxygen only if clinically indicated; n = 2668). Oxygen was given via nasal tubes at 3 L/min if baseline oxygen saturation was 93% or less and at 2 L/min if oxygen saturation was greater than 93%. The primary outcome was reported using the modified Rankin Scale score (disability range, 0 [no symptoms] to 6 [death]; minimum clinically important difference, 1 point), assessed at 90 days by postal questionnaire (participant aware, assessor blinded). The modified Rankin Scale score was analyzed by ordinal logistic regression, which yields a common odds ratio (OR) for a change from one disability level to the next better (lower) level; OR greater than 1.00 indicates improvement. A total of 8003 patients (4398 (55%) men; mean [SD] age, 72 [13] years; median National Institutes of Health Stroke Scale score, 5; mean baseline oxygen saturation, 96.6%) were enrolled. The

Hyperbaric oxygen therapy ameliorates acute brain injury after porcine intracerebral hemorrhage at high altitude.

PubMed

Zhu, Hai-tao; Bian, Chen; Yuan, Ji-chao; Liao, Xiao-jun; Liu, Wei; Zhu, Gang; Feng, Hua; Lin, Jiang-kai

2015-06-15

Intracerebral hemorrhage (ICH) at high altitude is not well understood to date. This study investigates the effects of high altitude on ICH, and examines the acute neuroprotection of hyperbaric oxygen (HBO) therapy against high-altitude ICH. Minipigs were placed in a hypobaric chamber for 72 h before the operation. ICH was induced by an infusion of autologous arterial blood (3 ml) into the right basal ganglia. Animals in the high-altitude ICH group received HBO therapy (2.5 ATA for 60 min) 30 min after ICH. Blood gas, blood glucose and brain tissue oxygen partial pressure (PbtO2) were monitored continuously for animals from all groups, as were microdialysis products including glucose, lactate, pyruvate and glutamate in perihematomal tissue from 3 to 12 h post-ICH. High-altitude ICH animals showed significantly lower PbtO2, higher lactate/pyruvate ratio (LPR) and glutamate levels than low-altitude ICH animals. More severe neurological deficits, brain edema and neuronal damage were also observed in high-altitude ICH. After HBO therapy, PbtO2 was significantly increased and LPR and glutamate levels were significantly decreased. Brain edema, neurological deficits and neuronal damage were also ameliorated. The data suggested a more serious disturbance of tissue oxygenation and cerebral metabolism in the acute stage after ICH at high altitude. Early HBO treatment reduced acute brain injury, perhaps through a mechanism involving the amelioration of the derangement of cerebral oxygenation and metabolism following high-altitude ICH.

Oxygen in the Setting of Acute Myocardial Infarction: Is It Really a Breath of Fresh Air?

PubMed

Loomba, Rohit S; Nijhawan, Karan; Aggarwal, Saurabh; Arora, Rohit R

2016-03-01

Supplemental oxygen has been used in the setting of acute myocardial infarction (AMI). Once an official recommendation in the guidelines for the management of acute ST-segment elevation myocardial infarction, it is now mentioned as an intervention to be considered. Data for the use of supplemental oxygen or AMI are limited, and some data have suggested associated harm. We performed a systematic review of the literature and a subsequent meta-analysis of the data to determine the effect of high concentration oxygen versus titrated oxygen or room air in the setting of AMI. The following end points were studied: in-hospital mortality, opiate use, percentage of infarcted myocardium by magnetic resonance imaging (MRI), and mass of infarcted myocardium by MRI. No significant difference was noted with end points when comparing those randomized to high-concentration oxygen versus those randomized to titrated oxygen or room air in the setting of AMI. No significant publication bias was identified although this could not be assessed for all end points. High-concentration oxygen may not offer any benefit when compared to titrated oxygen or room air. A large, randomized trial is warranted to further delineate these differences with respect to multiple end points. © The Author(s) 2015.

Hemoglobin oxygen affinty in patients with low-output heart failure and cardiogenic shock after acute myocardial infaraction.

PubMed

Agostoni, A; Lotto, A; Stabilini, R; Bernasconi, C; Gerli, G; Gattinoni, L; Lapichino, G; Sslvadé, P

1975-06-01

The aim of this study was to determine the oxigen affinity actually present in vivo in blood from patients with acute myocardial infarction. Patients with uncomplicated acute myocardial infarction had normal value of P50 in vivo (partial pressure of oxygen at which 50 percent of the hemoglobin is saturated with oxygen at fixed levels of pHand PC02 present in vivo). Also the values of P50 in vivo of blood from patients with low cardiac output with mild or severe heart failured did not differ from the normal mean. This was the consequence of an increase of 2, 3-diphosphoglycerate levels (which reduces the oxygen affinity of hemoglobin) and of the immediate effect of alkalosis (Bohr effect). By contrast, the values of P50 in vivo were significantly increased in patients with cardiogenic shock. This could be ascribed to the state of acute acidiosis present in these patients. In these conditions the changes in the values of P50 in vivo play an important role in the oxygen delivery to the tissues. However, high values of P50 do not enhance oxygen delivery when a severe arterial hypoxemia (P02 smaller than 40-45 mm Hg) is also present.

Acute oxygen therapy: a review of prescribing and delivery practices

PubMed Central

Cousins, Joyce L; Wark, Peter AB; McDonald, Vanessa M

2016-01-01

Oxygen is a commonly used drug in the clinical setting and like other drugs its use must be considered carefully. This is particularly true for those patients who are at risk of type II respiratory failure in whom the risk of hypercapnia is well established. In recent times, several international bodies have advocated for the prescription of oxygen therapy in an attempt to reduce this risk in vulnerable patient groups. Despite this guidance, published data have demonstrated that there has been poor uptake of these recommendations. Multiple interventions have been tested to improve concordance, and while some of these interventions show promise, the sustainability of these interventions are less convincing. In this review, we summarize data that have been published on the prevalence of oxygen prescription and the accurate and appropriate administration of this drug therapy. We also identify strategies that have shown promise in facilitating changes to oxygen prescription and delivery practice. There is a clear need to investigate the barriers, facilitators, and attitudes of clinicians in relation to the prescription of oxygen therapy in acute care. Interventions based on these findings then need to be designed and tested to facilitate the application of evidence-based guidelines to support sustained changes in practice, and ultimately improve patient care. PMID:27307722

Effect of Home Noninvasive Ventilation With Oxygen Therapy vs Oxygen Therapy Alone on Hospital Readmission or Death After an Acute COPD Exacerbation

PubMed Central

Rehal, Sunita; Arbane, Gill; Bourke, Stephen; Calverley, Peter M. A.; Crook, Angela M.; Dowson, Lee; Duffy, Nicholas; Gibson, G. John; Hughes, Philip D.; Hurst, John R.; Lewis, Keir E.; Mukherjee, Rahul; Nickol, Annabel; Oscroft, Nicholas; Patout, Maxime; Pepperell, Justin; Smith, Ian; Stradling, John R.; Wedzicha, Jadwiga A.; Polkey, Michael I.; Elliott, Mark W.; Hart, Nicholas

2017-01-01

Importance Outcomes after exacerbations of chronic obstructive pulmonary disease (COPD) requiring acute noninvasive ventilation (NIV) are poor and there are few treatments to prevent hospital readmission and death. Objective To investigate the effect of home NIV plus oxygen on time to readmission or death in patients with persistent hypercapnia after an acute COPD exacerbation. Design, Setting, and Participants A randomized clinical trial of patients with persistent hypercapnia (Paco2 >53 mm Hg) 2 weeks to 4 weeks after resolution of respiratory acidemia, who were recruited from 13 UK centers between 2010 and 2015. Exclusion criteria included obesity (body mass index [BMI] >35), obstructive sleep apnea syndrome, or other causes of respiratory failure. Of 2021 patients screened, 124 were eligible. Interventions There were 59 patients randomized to home oxygen alone (median oxygen flow rate, 1.0 L/min [interquartile range {IQR}, 0.5-2.0 L/min]) and 57 patients to home oxygen plus home NIV (median oxygen flow rate, 1.0 L/min [IQR, 0.5-1.5 L/min]). The median home ventilator settings were an inspiratory positive airway pressure of 24 (IQR, 22-26) cm H2O, an expiratory positive airway pressure of 4 (IQR, 4-5) cm H2O, and a backup rate of 14 (IQR, 14-16) breaths/minute. Main Outcomes and Measures Time to readmission or death within 12 months adjusted for the number of previous COPD admissions, previous use of long-term oxygen, age, and BMI. Results A total of 116 patients (mean [SD] age of 67 [10] years, 53% female, mean BMI of 21.6 [IQR, 18.2-26.1], mean [SD] forced expiratory volume in the first second of expiration of 0.6 L [0.2 L], and mean [SD] Paco2 while breathing room air of 59 [7] mm Hg) were randomized. Sixty-four patients (28 in home oxygen alone and 36 in home oxygen plus home NIV) completed the 12-month study period. The median time to readmission or death was 4.3 months (IQR, 1.3-13.8 months) in the home oxygen plus home NIV group vs 1.4 months (IQR, 0

Supplemental oxygen therapy does not affect the systemic inflammatory response to acute myocardial infarction.

PubMed

Hofmann, R; Tornvall, P; Witt, N; Alfredsson, J; Svensson, L; Jonasson, L; Nilsson, L

2018-04-01

Oxygen therapy has been used routinely in normoxemic patients with suspected acute myocardial infarction (AMI) despite limited evidence supporting a beneficial effect. AMI is associated with a systemic inflammation. Here, we hypothesized that the inflammatory response to AMI is potentiated by oxygen therapy. The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) multicentre trial randomized patients with suspected AMI to receive oxygen at 6 L min -1 for 6-12 h or ambient air. For this prespecified subgroup analysis, we recruited patients with confirmed AMI from two sites for evaluation of inflammatory biomarkers at randomization and 5-7 h later. Ninety-two inflammatory biomarkers were analysed using proximity extension assay technology, to evaluate the effect of oxygen on the systemic inflammatory response to AMI. Plasma from 144 AMI patients was analysed whereof 76 (53%) were randomized to oxygen and 68 (47%) to air. Eight biomarkers showed a significant increase, whereas 13 were decreased 5-7 h after randomization. The inflammatory response did not differ between the two treatment groups neither did plasma troponin T levels. After adjustment for increase in troponin T over time, age and sex, the release of inflammation-related biomarkers was still similar in the groups. In a randomized controlled setting of normoxemic patients with AMI, the use of supplemental oxygen did not have any significant impact on the early release of systemic inflammatory markers. © 2017 The Association for the Publication of the Journal of Internal Medicine.

Characteristics and Outcome of Patients After Allogeneic Hematopoietic Stem Cell Transplantation Treated With Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome.

PubMed

Wohlfarth, Philipp; Beutel, Gernot; Lebiedz, Pia; Stemmler, Hans-Joachim; Staudinger, Thomas; Schmidt, Matthieu; Kochanek, Matthias; Liebregts, Tobias; Taccone, Fabio Silvio; Azoulay, Elie; Demoule, Alexandre; Kluge, Stefan; Svalebjørg, Morten; Lueck, Catherina; Tischer, Johanna; Combes, Alain; Böll, Boris; Rabitsch, Werner; Schellongowski, Peter

2017-05-01

The acute respiratory distress syndrome is a frequent condition following allogeneic hematopoietic stem cell transplantation. Extracorporeal membrane oxygenation may serve as rescue therapy in refractory acute respiratory distress syndrome but has not been assessed in allogeneic hematopoietic stem cell transplantation recipients. Multicenter, retrospective, observational study. ICUs in 12 European tertiary care centers (Austria, Germany, France, and Belgium). All allogeneic hematopoietic stem cell transplantation recipients treated with venovenous extracorporeal membrane oxygenation for acute respiratory distress syndrome between 2010 and 2015. None. Thirty-seven patients, nine of whom underwent noninvasive ventilation at the time of extracorporeal membrane oxygenation initiation, were analyzed. ICU admission occurred at a median of 146 (interquartile range, 27-321) days after allogeneic hematopoietic stem cell transplantation. The main reason for acute respiratory distress syndrome was pneumonia in 81% of patients. All but one patient undergoing noninvasive ventilation at extracorporeal membrane oxygenation initiation had to be intubated thereafter. Overall, seven patients (19%) survived to hospital discharge and were alive and in remission of their hematologic disease after a follow-up of 18 (range, 5-30) months. Only one of 24 patients (4%) initiated on extracorporeal membrane oxygenation within 240 days after allogeneic hematopoietic stem cell transplantation survived compared to six of 13 (46%) of those treated thereafter (p < 0.01). Fourteen patients (38%) experienced bleeding events, of which six (16%) were associated with fatal outcomes. Discouraging survival rates in patients treated early after allogeneic hematopoietic stem cell transplantation do not support the use of extracorporeal membrane oxygenation for acute respiratory distress syndrome in this group. On the contrary, long-term allogeneic hematopoietic stem cell transplantation recipients

Routine low-dose continuous or nocturnal oxygen for people with acute stroke: three-arm Stroke Oxygen Supplementation RCT.

PubMed

Roffe, Christine; Nevatte, Tracy; Bishop, Jon; Sim, Julius; Penaloza, Cristina; Jowett, Susan; Ives, Natalie; Gray, Richard; Ferdinand, Phillip; Muddegowda, Girish

2018-03-01

Stroke is a major cause of death and disability worldwide. Hypoxia is common after stroke and is associated with worse outcomes. Oxygen supplementation could prevent hypoxia and secondary brain damage. (1) To assess whether or not routine low-dose oxygen supplementation in patients with acute stroke improves outcome compared with no oxygen; and (2) to assess whether or not oxygen given at night only, when oxygen saturation is most likely to be low, is more effective than continuous supplementation. Multicentre, prospective, randomised, open, blinded-end point trial. Secondary care hospitals with acute stroke wards. Adult stroke patients within 24 hours of hospital admission and 48 hours of stroke onset, without definite indications for or contraindications to oxygen or a life-threatening condition other than stroke. Allocated by web-based minimised randomisation to: (1) continuous oxygen: oxygen via nasal cannula continuously (day and night) for 72 hours after randomisation at a flow rate of 3 l/minute if baseline oxygen saturation was ≤ 93% or 2 l/minute if > 93%; (2) nocturnal oxygen: oxygen via nasal cannula overnight (21:00-07:00) for three consecutive nights. The flow rate was the same as the continuous oxygen group; and (3) control: no routine oxygen supplementation unless required for reasons other than stroke. Primary outcome: disability assessed by the modified Rankin Scale (mRS) at 3 months by postal questionnaire (participant aware, assessor blinded). Secondary outcomes at 7 days: neurological improvement, National Institutes of Health Stroke Scale (NIHSS), mortality, and the highest and lowest oxygen saturations within the first 72 hours. Secondary outcomes at 3, 6, and 12 months: mortality, independence, current living arrangements, Barthel Index, quality of life (European Quality of Life-5 Dimensions, three levels) and Nottingham Extended Activities of Daily Living scale by postal questionnaire. In total, 8003 patients were recruited between

Mechanisms of oxygen sensing: a key to therapy of pulmonary hypertension and patent ductus arteriosus

PubMed Central

Weir, E K; Obreztchikova, M; Vargese, A; Cabrera, J A; Peterson, D A; Hong, Z

2008-01-01

Specialized tissues that sense acute changes in the local oxygen tension include type 1 cells of the carotid body, neuroepithelial bodies in the lungs, and smooth muscle cells of the resistance pulmonary arteries and the ductus arteriosus (DA). Hypoxia inhibits outward potassium current in carotid body type 1 cells, leading to depolarization and calcium entry through L-type calcium channels. Increased intracellular calcium concentration ([Ca++]i) leads to exocytosis of neurotransmitters, thus stimulating the carotid sinus nerve and respiration. The same K+ channel inhibition occurs with hypoxia in pulmonary artery smooth muscle cells (PASMCs), causing contraction and providing part of the mechanism of hypoxic pulmonary vasoconstriction (HPV). In the SMCs of the DA, the mechanism works in reverse. It is the shift from hypoxia to normoxia that inhibits K+ channels and causes normoxic ductal contraction. In both PA and DA, the contraction is augmented by release of Ca++ from the sarcoplasmic reticulum, entry of Ca++ through store-operated channels (SOC) and by Ca++ sensitization. The same three ‘executive' mechanisms are partly responsible for idiopathic pulmonary arterial hypertension (IPAH). While vasoconstrictor mediators constrict both PA and DA and vasodilators dilate both vessels, only redox changes mimic oxygen by having directly opposite effects on the K+ channels, membrane potential, [Ca++]i and tone in the PA and DA. There are several different hypotheses as to how redox might alter tone, which remain to be resolved. However, understanding the mechanism will facilitate drug development for pulmonary hypertension and patent DA. PMID:18641675

Sensors, transmitters, and targets in mitochondrial oxygen shortage-a hypoxia-inducible factor relay story.

PubMed

Dehne, Nathalie; Brüne, Bernhard

2014-01-10

Cells sense and respond to a shortage of oxygen by activating the hypoxia-inducible transcription factors HIF-1 and HIF-2 and evoking adaptive responses. Mitochondria are at the center of a hypoxia sensing and responding relay system. Under normoxia, reactive oxygen species (ROS) and nitric oxide (NO) are HIF activators. As their individual flux rates determine their diffusion-controlled interaction, predictions how these radicals affect HIF appear context-dependent. Considering that the oxygen requirement for NO formation limits its role in activating HIF to conditions of ambient oxygen tension. Given the central role of mitochondrial complex IV as a NO target, especially under hypoxia, allows inhibition of mitochondrial respiration by NO to spare oxygen thus, raising the threshold for HIF activation. HIF targets seem to configure a feedback-signaling circuit aimed at gradually adjusting mitochondrial function. In hypoxic cancer cells, mitochondria redirect Krebs cycle intermediates to preserve their biosynthetic ability. Persistent HIF activation lowers the entry of electron-delivering compounds into mitochondria to reduce Krebs cycle fueling and β-oxidation, attenuates the expression of electron transport chain components, limits mitochondria biosynthesis, and provokes their removal by autophagy. Mitochondria can be placed central in a hypoxia sensing-hypoxia responding circuit. We need to determine to which extent and how mitochondria contribute to sense hypoxia, explore whether modulating their oxygen-consuming capacity redirects hypoxic responses in in vivo relevant disease conditions, and elucidate how the multiple HIF targets in mitochondria shape conditions of acute versus chronic hypoxia.

High-Flow Nasal Cannula Oxygenation in Immunocompromised Patients With Acute Hypoxemic Respiratory Failure: A Groupe de Recherche Respiratoire en Réanimation Onco-Hématologique Study.

PubMed

Lemiale, Virginie; Resche-Rigon, Matthieu; Mokart, Djamel; Pène, Frédéric; Argaud, Laurent; Mayaux, Julien; Guitton, Christophe; Rabbat, Antoine; Girault, Christophe; Kouatchet, Achille; Vincent, François; Bruneel, Fabrice; Nyunga, Martine; Seguin, Amélie; Klouche, Kada; Colin, Gwenahel; Kontar, Loay; Perez, Pierre; Meert, Anne-Pascale; Benoit, Dominique D; Papazian, Laurent; Demoule, Alexandre; Chevret, Sylvie; Azoulay, Elie

2017-03-01

In immunocompromised patients with acute respiratory failure, invasive mechanical ventilation remains associated with high mortality. Choosing the adequate oxygenation strategy is of the utmost importance in that setting. High-flow nasal oxygen has recently shown survival benefits in unselected patients with acute respiratory failure. The objective was to assess outcomes of immunocompromised patients with hypoxemic acute respiratory failure treated with high-flow nasal oxygen. We performed a post hoc analysis of a randomized controlled trial of noninvasive ventilation in critically ill immunocompromised patients with hypoxemic acute respiratory failure. Twenty-nine ICUs in France and Belgium. Critically ill immunocompromised patients with hypoxemic acute respiratory failure. A propensity score-based approach was used to assess the impact of high-flow nasal oxygen compared with standard oxygen on day 28 mortality. Among 374 patients included in the study, 353 met inclusion criteria. Underlying disease included mostly malignancies (n = 296; 84%). Acute respiratory failure etiologies were mostly pneumonia (n = 157; 44.4%) or opportunistic infection (n = 76; 21.5%). Noninvasive ventilation was administered to 180 patients (51%). Invasive mechanical ventilation was ultimately needed in 142 patients (40.2%). Day 28 mortality was 22.6% (80 deaths). Throughout the ICU stay, 127 patients (36%) received high-flow nasal oxygen whereas 226 patients received standard oxygen. Ninety patients in each group (high-flow nasal oxygen or standard oxygen) were matched according to the propensity score, including 91 of 180 (51%) who received noninvasive ventilation. High-flow nasal oxygen was neither associated with a lower intubation rate (hazard ratio, 0.42; 95% CI, 0.11-1.61; p = 0.2) nor day 28 mortality (hazard ratio, 0.80; 95% CI, 0.45-1.42; p = 0.45). In immunocompromised patients with hypoxemic acute respiratory failure, high-flow nasal oxygen when compared with standard oxygen

Iron and oxygen sensing: a tale of 2 interacting elements?

PubMed

Simpson, Robert J; McKie, Andrew T

2015-02-01

Iron and oxygen metabolism are intimately linked with one another. A change in the level of either metabolite results in activation of common pathways. At the heart of these responses lies a group of iron and oxygen dependent enzymes called prolyl hydroxylases. Prolyl hydroxylases (PHDs) require both iron and oxygen for optimal activity and their biological activity is to carry out the critical post-translational modification of the addition of a hydroxyl group to specific proline residues within Hypoxia Inducible Factor (HIFs)-well known transcription factors originally thought to regulate responses to hypoxia but which are now known to regulate key iron metabolism proteins too. The addition of the hydroxyl group ultimately leads to the unbiquitylation and destruction of HIFs, thus PHDs control appropriate HIF transcriptional responses depending on cellular oxygen or iron levels. There are two major HIFs; HIF1α and HIF2α. In terms of responses to iron HIF2α is of major importance in key tissues such as the intestine where several iron transporters (Ferroportin, Dcytb) contain HREs within their promoters which bind HIF2α. Furthermore the recent discovery that HIF2α contains a 5' iron responsive element (IRE) has underlined the importance of HIF2α as a major player in iron metabolism. This review brings together recent findings with regard to the HIF2α/IRP network as well as other aspects of iron sensing in cells and tissues.

Extracorporeal Membrane Oxygenation for Refractory Severe Respiratory Failure in Acute Interstitial Pneumonia.

PubMed

Gonçalves-Venade, Gabriela; Lacerda-Príncipe, Nuno; Roncon-Albuquerque, Roberto; Paiva, José Artur

2018-05-01

Acute interstitial pneumonia (AIP) is a rare idiopathic interstitial lung disease with rapid progressive respiratory failure and high mortality. In the present report, three cases of AIP complicated by refractory respiratory failure supported with extracorporeal membrane oxygenation (ECMO) are presented. One male and two female patients (ages 27-59) were included. Venovenous ECMO support was provided using miniaturized systems, with two-site femoro-jugular circuit configuration. Despite lung protective ventilation, prone position and neuromuscular blockade, refractory respiratory failure of unknown etiology supervened (ratio of arterial oxygen partial pressure to fractional inspired oxygen 46-130) and ECMO was initiated after 3-7 days of mechanical ventilation. AIP diagnosis was established after exclusion of infectious and noninfectious acute respiratory distress syndrome on the basis of clinical and analytical data, bronchoalveolar lavage analysis and lung imaging, with a confirmatory surgical lung biopsy revealing diffuse alveolar damage of unknown etiology. Immunosuppressive treatment consisted in high-dose corticosteroids and cyclophosphamide in one case. Two patients survived to hospital discharge. ECMO allowed AIP diagnosis and treatment in the presence of refractory respiratory failure, therefore reducing ventilator-induced lung injury and bridging lung recovery in two patients. ECMO referral should be considered in refractory respiratory failure if AIP is suspected. © 2018 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Hyperbaric oxygen in skeletal muscle of rats submitted to total acute left hindlimb ischemia: A research report.

PubMed

da Silva, Luis Gustavo Campos; Dalio, Marcelo Bellini; Joviliano, Edwaldo Edner; Feres, Omar; Piccinato, Carlos Eli

2015-01-01

Determine the effect of hyperbaric oxygen treatment in skeletal muscle of rats submitted to total acute left hindlimb ischemia. An experimental study was designed using 48 Wistar rats divided into four groups (n = 12): Control; Ischemia (I)--total hindlimb ischemia for 270 minutes; Hyperbaric oxygen treatment during ischemia (HBO2)--total hindlimb ischemia for 270 minutes and hyperbaric oxygen during the first 90 minutes; Pre-treatment with hyperbaric oxygen (PHBO2)--90 minutes of hyperbaric oxygen treatment before total hindlimb ischemia for 270 minutes. Skeletal muscle injury was evaluated by measuring levels of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), total creatine phosphokinase (CPK); muscular malondialdehyde (MDA), muscular glycogen, and serum ischemia-modified albumin (IMA). AST was significantly higher in I, HBO2 and PHBO2 compared with control (P = .001). There was no difference in LDH. CPK was significantly higher in I, HBO2 and PHBO2, compared with control (p = .014). MDA was significantly higher in PHBO2, compared with other groups (p = .042). Glycogen was significantly decreased in I, HBO2 and PHBO2, compared with control (p < .001). Hyperbaric oxygen treatment in acute total hindlimb ischemia exerted no protective effect on muscle injury, regardless of time of application. When applied prior to installation of total ischemia, hyperbaric oxygen treatment aggravated muscle injury.

Oxygen optical gas sensing by reversible fluorescence quenching in photo-oxidized poly(9,9-dioctylfluorene) thin films.

PubMed

Anni, M; Rella, R

2010-02-04

We investigated the fluorescence (FL) dependence on the environment oxygen content of poly(9,9-dioctylfluorene) (PF8) thin films. We show that the PF8 interactions with oxygen are not limited to the known irreversible photo-oxidation, resulting in the formation of Keto defects, but also reversible FL quenching is observed. This effect, which is stronger for the Keto defects than for the PF8, has been exploited for the realization of a prototype oxygen sensor based on FL quenching. The sensing sensitivity of Keto defects is comparable with the state of the art organic oxygen sensors based on phosphorescence quenching.

Severe transfusion-related acute lung injury managed with extracorporeal membrane oxygenation (ECMO) in an obstetric patient.

PubMed

Lee, Allison J; Koyyalamudi, Pushpa L; Martinez-Ruiz, Ricardo

2008-11-01

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related mortality in the United States. Management is usually supportive, including supplemental oxygen, intravenous fluids, and mechanical ventilation if necessary. Most patients recover within 72 hours. We present a nearly fatal case of TRALI in an obstetric patient, which was successfully managed with extracorporeal membrane oxygenation (ECMO).

Effect of Routine Low-Dose Oxygen Supplementation on Death and Disability in Adults With Acute Stroke

PubMed Central

Nevatte, Tracy; Sim, Julius; Bishop, Jon; Ives, Natalie; Ferdinand, Phillip; Gray, Richard

2017-01-01

Importance Hypoxia is common in the first few days after acute stroke, is frequently intermittent, and is often undetected. Oxygen supplementation could prevent hypoxia and secondary neurological deterioration and thus has the potential to improve recovery. Objective To assess whether routine prophylactic low-dose oxygen therapy was more effective than control oxygen administration in reducing death and disability at 90 days, and if so, whether oxygen given at night only, when hypoxia is most frequent, and oxygen administration is least likely to interfere with rehabilitation, was more effective than continuous supplementation. Design, Setting, and Participants In this single-blind randomized clinical trial, 8003 adults with acute stroke were enrolled from 136 participating centers in the United Kingdom within 24 hours of hospital admission if they had no clear indications for or contraindications to oxygen treatment (first patient enrolled April 24, 2008; last follow-up January 27, 2015). Interventions Participants were randomized 1:1:1 to continuous oxygen for 72 hours (n = 2668), nocturnal oxygen (21:00 to 07:00 hours) for 3 nights (n = 2667), or control (oxygen only if clinically indicated; n = 2668). Oxygen was given via nasal tubes at 3 L/min if baseline oxygen saturation was 93% or less and at 2 L/min if oxygen saturation was greater than 93%. Main Outcomes and Measures The primary outcome was reported using the modified Rankin Scale score (disability range, 0 [no symptoms] to 6 [death]; minimum clinically important difference, 1 point), assessed at 90 days by postal questionnaire (participant aware, assessor blinded). The modified Rankin Scale score was analyzed by ordinal logistic regression, which yields a common odds ratio (OR) for a change from one disability level to the next better (lower) level; OR greater than 1.00 indicates improvement. Results A total of 8003 patients (4398 (55%) men; mean [SD] age, 72 [13] years; median National

Oxygen-sensing PHDs regulate bone homeostasis through the modulation of osteoprotegerin

PubMed Central

Wu, Colleen; Rankin, Erinn B.; Castellini, Laura; Fernandez-Alcudia, Javier; LaGory, Edward L.; Andersen, Rebecca; Rhodes, Steven D.; Wilson, Tremika L.S.; Mohammad, Khalid S.; Castillo, Alesha B.; Guise, Theresa A.; Schipani, Ernestina

2015-01-01

The bone microenvironment is composed of niches that house cells across variable oxygen tensions. However, the contribution of oxygen gradients in regulating bone and blood homeostasis remains unknown. Here, we generated mice with either single or combined genetic inactivation of the critical oxygen-sensing prolyl hydroxylase (PHD) enzymes (PHD1–3) in osteoprogenitors. Hypoxia-inducible factor (HIF) activation associated with Phd2 and Phd3 inactivation drove bone accumulation by modulating osteoblastic/osteoclastic cross-talk through the direct regulation of osteoprotegerin (OPG). In contrast, combined inactivation of Phd1, Phd2, and Phd3 resulted in extreme HIF signaling, leading to polycythemia and excessive bone accumulation by overstimulating angiogenic–osteogenic coupling. We also demonstrate that genetic ablation of Phd2 and Phd3 was sufficient to protect ovariectomized mice against bone loss without disrupting hematopoietic homeostasis. Importantly, we identify OPG as a HIF target gene capable of directing osteoblast-mediated osteoclastogenesis to regulate bone homeostasis. Here, we show that coordinated activation of specific PHD isoforms fine-tunes the osteoblastic response to hypoxia, thereby directing two important aspects of bone physiology: cross-talk between osteoblasts and osteoclasts and angiogenic–osteogenic coupling. PMID:25846796

Acetazolamide during acute hypoxia improves tissue oxygenation in the human brain.

PubMed

Wang, Kang; Smith, Zachary M; Buxton, Richard B; Swenson, Erik R; Dubowitz, David J

2015-12-15

Low doses of the carbonic anhydrase inhibitor acetazolamide provides accelerated acclimatization to high-altitude hypoxia and prevention of cerebral and other symptoms of acute mountain sickness. We previously observed increases in cerebral O2 metabolism (CMRO2 ) during hypoxia. In this study, we investigate whether low-dose oral acetazolamide (250 mg) reduces this elevated CMRO2 and in turn might improve cerebral tissue oxygenation (PtiO2 ) during acute hypoxia. Six normal human subjects were exposed to 6 h of normobaric hypoxia with and without acetazolamide prophylaxis. We determined CMRO2 and cerebral PtiO2 from MRI measurements of cerebral blood flow (CBF) and cerebral venous O2 saturation. During normoxia, low-dose acetazolamide resulted in no significant change in CBF, CMRO2 , or PtiO2 . During hypoxia, we observed increases in CBF [48.5 (SD 12.4) (normoxia) to 65.5 (20.4) ml·100 ml(-1)·min(-1) (hypoxia), P < 0.05] and CMRO2 [1.54 (0.19) to 1.79 (0.25) μmol·ml(-1)·min(-1), P < 0.05] and a dramatic decline in PtiO2 [25.0 to 11.4 (2.7) mmHg, P < 0.05]. Acetazolamide prophylaxis mitigated these rises in CBF [53.7 (20.7) ml·100 ml(-1)·min(-1) (hypoxia + acetazolamide)] and CMRO2 [1.41 (0.09) μmol·ml(-1)·min(-1) (hypoxia + acetazolamide)] associated with acute hypoxia but also reduced O2 delivery [6.92 (1.45) (hypoxia) to 5.60 (1.14) mmol/min (hypoxia + acetazolamide), P < 0.05]. The net effect was improved cerebral tissue PtiO2 during acute hypoxia [11.4 (2.7) (hypoxia) to 16.5 (3.0) mmHg (hypoxia + acetazolamide), P < 0.05]. In addition to its renal effect, low-dose acetazolamide is effective at the capillary endothelium, and we hypothesize that local interruption in cerebral CO2 excretion accounts for the improvements in CMRO2 and ultimately in cerebral tissue oxygenation during hypoxia. This study suggests a potentially pivotal role of cerebral CO2 and pH in modulating CMRO2 and PtiO2 during acute hypoxia. Copyright © 2015 the American

Acute cocoa flavanol improves cerebral oxygenation without enhancing executive function at rest or after exercise.

PubMed

Decroix, Lieselot; Tonoli, Cajsa; Soares, Danusa D; Tagougui, Semah; Heyman, Elsa; Meeusen, Romain

2016-12-01

Acute exercise-induced improvements in cognitive function are accompanied by increased (cerebral) blood flow and increased brain-derived neurotrophic factor (BDNF) levels. Acute cocoa flavanol (CF) intake may improve cognitive function, cerebral blood flow (in humans), and BNDF levels (in animals). This study investigated (i) the effect of CF intake in combination with exercise on cognitive function and (ii) cerebral hemodynamics and BDNF in response to CF intake and exercise. Twelve healthy men participated in this randomized, double-blind, crossover study. Participants performed a cognitive task (CT) at 100 min after acute 903-mg CF or placebo (PL) intake, followed by a 30-min time-trial. Immediately after this exercise, the same CT was performed. Prefrontal near-infrared spectroscopy was applied during CT and exercise to measure changes in oxygenated (ΔHbO 2 ), deoxygenated (ΔHHb), and total haemoglobin (ΔHb tot ) and blood samples were drawn and analyzed for BDNF. Reaction time was faster postexercise, but was not influenced by CF. ΔHbO 2 during the resting CT was increased by CF, compared with PL. ΔHbO 2 , ΔHHb, and ΔHb tot increased in response to exercise without any effect of CF. During the postexercise cognitive task, there were no hemodynamic differences between CF or PL. Serum BDNF was increased by exercise, but was not influenced by CF. In conclusion, at rest, CF intake increased cerebral oxygenation, but not BDNF concentrations, and no impact on executive function was detected. This beneficial effect of CF on cerebral oxygenation at rest was overruled by the strong exercise-induced increases in cerebral perfusion and oxygenation.

Health-related quality of life, sense of coherence and leisure-time physical activity in women after an acute myocardial infarction.

PubMed

Løvlien, Mona; Mundal, Liv; Hall-Lord, Marie-Louise

2017-04-01

To examine the relationship between leisure-time physical activity, health-related quality of life and sense of coherence in women after an acute myocardial infarction, and further to investigate whether these aspects were associated with age. Physical activity and health-related quality of life are vital aspects for patients after an acute myocardial infarction. Cross-sectional. All eligible women diagnosed with acute myocardial infarction received a postal questionnaire two to three months after hospital discharge, and 142 women were included. To measure health-related quality of life and sense of coherence, The MacNew Heart disease questionnaire and the Sense of coherence-13 scale was used. Respondents reporting at least one type of physical activity had significantly higher health-related quality of life as compared to respondents reporting no kind of physical activity. Respondents reporting physical activity for at least 30 minutes twice a week had significantly higher health-related quality of life scores than respondents being active less than twice a week. A weak association was found between physical activity level and sense of coherence. Reduction in physical activity after the acute myocardial infarction was associated with reduced health-related quality of life and sense of coherence. Sense of coherence was significantly associated with age, as respondents 75 years and older had significantly higher scores than respondents younger than 75 years. Physical activity, even at a low level, is significantly associated with increased health-related quality of life and to some extent to sense of coherence. Tailoring women after an acute myocardial infarction about lifestyle changes must include knowledge about the benefits of leisure-time physical activity, and that even a small amount of activity is associated with a better health-related quality of life. The utmost important assignment is to motivate the women for regular physical activity in their leisure

Pharyngeal oxygen administration increases the time to serious desaturation at intubation in acute lung injury: an experimental study

PubMed Central

2010-01-01

Introduction Endotracheal intubation in critically ill patients is associated with severe life-threatening complications in about 20%, mainly due to hypoxemia. We hypothesized that apneic oxygenation via a pharyngeal catheter during the endotracheal intubation procedure would prevent or increase the time to life-threatening hypoxemia and tested this hypothesis in an acute lung injury animal model. Methods Eight anesthetized piglets with collapse-prone lungs induced by lung lavage were ventilated with a fraction of inspired oxygen of 1.0 and a positive end-expiratory pressure of 5 cmH2O. The shunt fraction was calculated after obtaining arterial and mixed venous blood gases. The trachea was extubated, and in randomized order each animal received either 10 L oxygen per minute or no oxygen via a pharyngeal catheter, and the time to desaturation to pulse oximeter saturation (SpO2) 60% was measured. If SpO2 was maintained at over 60%, the experiment ended when 10 minutes had elapsed. Results Without pharyngeal oxygen, the animals desaturated after 103 (88-111) seconds (median and interquartile range), whereas with pharyngeal oxygen five animals had a SpO2 > 60% for the 10-minute experimental period, one animal desaturated after 7 minutes, and two animals desaturated within 90 seconds (P < 0.016, Wilcoxon signed rank test). The time to desaturation was related to shunt fraction (R2 = 0.81, P = 0.002, linear regression); the animals that desaturated within 90 seconds had shunt fractions >40%, whereas the others had shunt fractions <25%. Conclusions In this experimental acute lung injury model, pharyngeal oxygen administration markedly prolonged the time to severe desaturation during apnea, suggesting that this technique might be useful when intubating critically ill patients with acute respiratory failure. PMID:20497538

Renal oxygenation and hemodynamics in acute kidney injury and chronic kidney disease

PubMed Central

Singh, Prabhleen; Ricksten, Sven-Erik; Bragadottir, Gudrun; Redfors, Bengt; Nordquist, Lina

2013-01-01

Summary 1. Acute kidney injury (AKI) puts a major burden on health systems that may arise from multiple initiating insults, including ischemia-reperfusion injury, cardiovascular surgery, radio-contrast administration as well as sepsis. Similarly, the incidence and prevalence of chronic kidney disease (CKD) continues to increase with significant morbidity and mortality. Moreover, an increasing number of AKI patients survive to develop CKD and end-stage kidney disease (ESRD). 2. Although the mechanisms for development of AKI and progression of CKD remain poorly understood, initial impairment of oxygen balance is likely to constitute a common pathway, causing renal tissue hypoxia and ATP starvation that will in turn induce extracellular matrix production, collagen deposition and fibrosis. Thus, possible future strategies for one or both conditions may involve dopamine, loop-diuretics, inducible nitric oxide synthase inhibitors and atrial natriuretic peptide, substances that target kidney oxygen consumption and regulators of renal oxygenation such as nitric oxide and heme oxygenase-1. PMID:23360244

Positioning of patients with acute respiratory distress syndrome: combining prone and upright makes sense.

PubMed

Richard, Jean-Christophe M; Lefebvre, Jean-Claude

2011-01-01

Positional strategies have been proposed for mechanically ventilated patients with acute respiratory distress syndrome. Despite different physiological mechanisms involved, oxygenation improvement has been demonstrated with both prone and upright positions. In the previous issue of Critical Care, Robak and colleagues reported the first study evaluating the short-term effects of combining prone and upright positioning. The combined positioning enhanced the response rate in terms of oxygenation. Other benefits, such as a reduction in ventilator-associated pneumonia and better enteral feeding tolerance, can potentially be expected.

Low Oxygen Delivery as a Predictor of Acute Kidney Injury during Cardiopulmonary Bypass.

PubMed

Newland, Richard F; Baker, Robert A

2017-12-01

Low indexed oxygen delivery (DO 2 i) during cardiopulmonary bypass (CPB) has been associated with an increase in the likelihood of acute kidney injury (AKI), with critical thresholds for oxygen delivery reported to be 260-270 mL/min/m 2 . This study aims to explore whether a relationship exists for oxygen delivery during CPB, in which the integral of amount and time below a critical threshold, is associated with the incidence of postoperative AKI. The area under the curve (AUC) with DO 2 i during CPB above or below 270 mL/min/m 2 was calculated as a metric of oxygen delivery in 210 patients undergoing CPB. To determine the influence of low oxygen delivery on AKI, a multivariate logistic regression model was developed including AUC < 0, Euroscore II to provide preoperative risk factor adjustment, and incidence of red blood cell transfusion to adjust for the influence of transfusion. Having an AUC < 0 for an oxygen delivery threshold of 270 mL/min/m 2 during CPB was an independent predictor of AKI, after adjustment for Euroscore II and transfusion [OR 2.74, CI {1.01-7.41}, p = .047]. These results support that a relationship exists for oxygen delivery during CPB, in which the integral of amount and time below a critical threshold is associated with the incidence of postoperative AKI.

Lung lavage with oxygenated perfluorochemical liquid in acute lung injury.

PubMed

Richman, P S; Wolfson, M R; Shaffer, T H

1993-05-01

To investigate the effects of lung lavage with oxygenated liquid perfluorochemical on gas exchange, lung mechanics, and cardiac function in animals with acute lung injury. Prospective, randomized, controlled trial. Animal laboratory. Eight adult cats (2 to 4 kg, random sex). Two insults were combined to cause lung injury: oleic acid infusion and saline whole-lung wash. Animals were assigned to either the control or treatment group which consisted of a perfluorochemical liquid (Rimar 101) lavage. Perfluorochemical liquid lavage was performed three times at hourly intervals after lung injury. Three other cats with identical injury but no perfluorochemical liquid lavage served as control animals. All cats were ventilated with an FIO2 of 0.95 and positive end-expiratory pressure of 2 cm H2O continuously. Arterial blood gas tensions and pH, dynamic pulmonary compliance were measured at 15-min intervals. Cardiac index was assessed hourly, and lung fluid was collected after each of the three perfluorochemical liquid lavages. Arterial oxygen tension and pulmonary compliance deteriorated abruptly after lung injury in all cats, and improved significantly (p < .001, two-way analysis of variance) 15 mins after perfluorochemical liquid lavage. These parameters gradually returned to their baseline over 60 mins. Arterial blood pressure and cardiac index decreased after injury in all cats, and were not significantly changed after perfluorochemical liquid lavage. Hemorrhagic fluid was recovered from distal airways by perfluorochemical liquid lavage, despite prior suctioning of the airway. Perfluorochemical liquid lavage removes pulmonary edema fluid and improves gas exchange and the mechanical properties of the lung, after acute severe lung injury.

Effect of oxygen plasma modification on refractive index sensing with micro-cavity in-line Mach-Zehnder interferometer

NASA Astrophysics Data System (ADS)

Debowska, Anna K.; Dominik, Magdalena; Koba, Marcin; Janik, Monika; Bock, Wojtek; Śmietana, Mateusz

2016-12-01

A micro-cavity in-line Mach-Zehnder interferometer (μIMZI) is an optical sensing structure fabricated in an optical fiber. Its design allows for refractive index sensing of liquid and gas in picoliter volumes, making it suitable for biochemical and medical sensing where measured material is often scarce. The fabricated structures show satisfactory levels of sensitivity, from about 400 nm/RIU in the near-water range of solutions (nD 1.336+/-0.003 RIU) to about 16 000 nm/RIU for solutions in approximate range from nD = 1.35 RIU to nD = 1.4 RIU. The structures were subjected to oxygen plasma, the process which was supposed to modify physical parameters of the structures, i.e., cavity surface wettability and roughness, and in consequence their sensitivity. As a result of the oxygen plasma modification we have observed a improved wettability of the structure surface, what makes it easier to introduce liquid into the cavity and simplifies the measurement process. In the case where the plasma processing is preceded by biological layer deposition, the bottom surface of the structure is smoothed and slightly deepened, causing a shift in the transmission spectrum and change in sensitivity.

Effect of Acute Dietary Nitrate Consumption on Oxygen Consumption During Submaximal Exercise in Hypobaric Hypoxia.

PubMed

Carriker, Colin R; Mermier, Christine M; Van Dusseldorp, Trisha A; Johnson, Kelly E; Beltz, Nicholas M; Vaughan, Roger A; McCormick, James J; Cole, Nathan H; Witt, Christopher C; Gibson, Ann L

2016-08-01

Reduced partial pressure of oxygen impairs exercise performance at altitude. Acute nitrate supplementation, at sea level, may reduce oxygen cost during submaximal exercise in hypobaric hypoxia. Therefore, we investigated the metabolic response during exercise at altitude following acute nitrate consumption. Ten well-trained (61.0 ± 7.4 ml/kg/min) males (age 28 ± 7 yr) completed 3 experimental trials (T1, T2, T3). T1 included baseline demographics, a maximal aerobic capacity test (VO2max) and five submaximal intensity cycling determination bouts at an elevation of 1600 m. A 4-day dietary washout, minimizing consumption of nitrate-rich foods, preceded T2 and T3. In a randomized, double-blind, placebo-controlled, crossover fashion, subjects consumed either a nitrate-depleted beetroot juice (PL) or ~12.8 mmol nitrate rich (NR) beverage 2.5 hr before T2 and T3. Exercise at 3500 m (T2 and T3) via hypobaric hypoxia consisted of a 5-min warm-up (25% of normobaric VO2max) and four 5-min cycling bouts (40, 50, 60, 70% of normobaric VO2max) each separated by a 4-min rest period. Cycling RPM and watts for each submaximal bout during T2 and T3 were determined during T1. Preexercise plasma nitrite was elevated following NR consumption compared with PL (1.4 ± 1.2 and 0.7 ± 0.3 uM respectively; p < .05). There was no difference in oxygen consumption (-0.5 ± 1.8, 0.1 ± 1.7, 0.7 ± 2.1, and 1.0 ± 3.0 ml/kg/min) at any intensity (40, 50, 60, 70% of VO2max, respectively) between NR and PL. Further, respiratory exchange ratio, oxygen saturation, heart rate and rating of perceived exertion were not different at any submaximal intensity between NR and PL either. Blood lactate, however, was reduced following NR consumption compared with PL at 40 and 60% of VO2max (p < .0.05). Our findings suggest that acute nitrate supplementation before exercise at 3500 m does not reduce oxygen cost but may reduce blood lactate accumulation at lower intensity workloads.

Integrated optical sensing of dissolved oxygen in microtiter plates: a novel tool for microbial cultivation.

PubMed

John, Gernot T; Klimant, Ingo; Wittmann, Christoph; Heinzle, Elmar

2003-03-30

Microtiter plates with integrated optical sensing of dissolved oxygen were developed by immobilization of two fluorophores at the bottom of 96-well polystyrene microtiter plates. The oxygen-sensitive fluorophore responded to dissolved oxygen concentration, whereas the oxygen-insensitive one served as an internal reference. The sensor measured dissolved oxygen accurately in optically well-defined media. Oxygen transfer coefficients, k(L)a, were determined by a dynamic method in a commercial microtiter plate reader with an integrated shaker. For this purpose, the dissolved oxygen was initially depleted by the addition of sodium dithionite and, by oxygen transfer from air, it increased again after complete oxidation of dithionite. k(L)a values in one commercial reader were about 10 to 40 h(-1). k(L)a values were inversely proportional to the filling volume and increased with increasing shaking intensity. Dissolved oxygen was monitored during cultivation of Corynebacterium glutamicum in another reader that allowed much higher shaking intensity. Growth rates determined from optical density measurement were identical to those observed in shaking flasks and in a stirred fermentor. Oxygen uptake rates measured in the stirred fermentor and dissolved oxygen concentrations measured during cultivation in the microtiter plate were used to estimate k(L)a values in a 96-well microtiter plate. The resulting values were about 130 h(-1), which is in the lower range of typical stirred fermentors. The resulting maximum oxygen transfer rate was 26 mM h(-1). Simulations showed that the errors caused by the intermittent measurement method were insignificant under the prevailing conditions. Copyright 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 829-836, 2003.

Experimental assessment of oxygen homeostasis during acute hemodilution: the integrated role of hemoglobin concentration and blood pressure.

PubMed

Kei, Tiffanie; Mistry, Nikhil; Tsui, Albert K Y; Liu, Elaine; Rogers, Stephen; Doctor, Allan; Wilson, David F; Desjardins, Jean-Francois; Connelly, Kim; Mazer, C David; Hare, Gregory M T

2017-12-01

Low hemoglobin concentration (Hb) and low mean arterial blood pressure (MAP) impact outcomes in critically ill patients. We utilized an experimental model of "normotensive" vs. "hypotensive" acute hemodilutional anemia to test whether optimal tissue perfusion is dependent on both Hb and MAP during acute blood loss and fluid resuscitation, and to assess the value of direct measurements of the partial pressure of oxygen in tissue (P t O 2 ). Twenty-nine anesthetized rats underwent 40% isovolemic hemodilution (1:1) (or sham-hemodilution control, n = 4) with either hydroxyethyl starch (HES) (n = 14, normotensive anemia) or saline (n = 11, hypotensive anemia) to reach a target Hb value near 70 g/L. The partial pressure of oxygen in the brain and skeletal muscle tissue (P t O 2 ) were measured by phosphorescence quenching of oxygen using G4 Oxyphor. Mean arterial pressure (MAP), heart rate, temperature, arterial and venous co-oximetry, blood gases, and lactate were assessed at baseline and for 60 min after hemodilution. Cardiac output (CO) was measured at baseline and immediately after hemodilution. Data were analyzed by repeated measures two-way ANOVA. Following "normotensive" hemodilution with HES, Hb was reduced to 66 ± 6 g/L, CO increased (p < 0.05), and MAP was maintained. These conditions resulted in a reduction in brain P t O 2 (22.1 ± 5.6 mmHg to 17.5 ± 4.4 mmHg, p < 0.05), unchanged muscle PO 2 , and an increase in venous oxygen extraction. Following "hypotensive" hemodilution with saline, Hb was reduced to 79 ± 5 g/L and both CO and MAP were decreased (P < 0.05). These conditions resulted in a more severe reduction in brain P t O 2 (23.2 ± 8.2 to 10.7 ± 3.6 mmHg (p < 0.05), a reduction in muscle P t O 2 (44.5 ± 11.0 to 19.9 ± 12.4 mmHg, p < 0.05), a further increase in venous oxygen extraction, and a threefold increase in systemic lactate levels (p < 0.05). Acute normotensive

Acute detachment of hexokinase II from mitochondria modestly increases oxygen consumption of the intact mouse heart.

PubMed

Nederlof, Rianne; Denis, Simone; Lauzier, Benjamin; Rosiers, Christine Des; Laakso, Markku; Hagen, Jacob; Argmann, Carmen; Wanders, Ronald; Houtkooper, Riekelt H; Hollmann, Markus W; Houten, Sander M; Zuurbier, Coert J

2017-07-01

Cardiac hexokinase II (HKII) can translocate between cytosol and mitochondria and change its cellular expression with pathologies such as ischemia-reperfusion, diabetes and heart failure. The cardiac metabolic consequences of these changes are unknown. Here we measured energy substrate utilization in cytosol and mitochondria using stabile isotopes and oxygen consumption of the intact perfused heart for 1) an acute decrease in mitochondrial HKII (mtHKII), and 2) a chronic decrease in total cellular HKII. We first examined effects of 200nM TAT (Trans-Activator of Transcription)-HKII peptide treatment, which was previously shown to acutely decrease mtHKII by ~30%. In Langendorff-perfused hearts TAT-HKII resulted in a modest, but significant, increased oxygen consumption, while cardiac performance was unchanged. At the metabolic level, there was a nonsignificant (p=0.076) ~40% decrease in glucose contribution to pyruvate and lactate formation through glycolysis and to mitochondrial citrate synthase flux (6.6±1.1 vs. 11.2±2.2%), and an 35% increase in tissue pyruvate (27±2 vs. 20±2pmol/mg; p=0.033). Secondly, we compared WT and HKII +/- hearts (50% chronic decrease in total HKII). RNA sequencing revealed no differential gene expression between WT and HKII +/- hearts indicating an absence of metabolic reprogramming at the transcriptional level. Langendorff-perfused hearts showed no significant differences in glycolysis (0.34±0.03μmol/min), glucose contribution to citrate synthase flux (35±2.3%), palmitate contribution to citrate synthase flux (20±1.1%), oxygen consumption or mechanical performance between WT and HKII +/- hearts. These results indicate that acute albeit not chronic changes in mitochondrial HKII modestly affect cardiac oxygen consumption and energy substrate metabolism. Copyright © 2017 Elsevier Inc. All rights reserved.

Anaemia: can we define haemoglobin thresholds for impaired oxygen homeostasis and suggest new strategies for treatment?

PubMed

Hare, Gregory M T; Tsui, Albert K Y; Ozawa, Sherri; Shander, Aryeh

2013-03-01

Observational clinical studies in perioperative medicine have defined a progressive increase in mortality that is proportional to both chronic preoperative anaemia and acute interpretative reductions in haemoglobin concentration (Hb). However, this knowledge has not yet helped to define the critical Hb threshold for organ injury and mortality in specific patient populations or in individual patients. Nor has this knowledge enabled us to develop effective treatment strategies for anaemia, as evident from the lack of a demonstrable improvement in survival in patients randomised to higher Hb levels by various treatment strategies including allogeneic red blood cell transfusion, erythropoiesis-stimulating agents (ESAs) and haemoglobin-based oxygen carriers (HBOCs). These findings emphasise the need for a clearer understanding of the mechanism of anaemia-induced mortality. Towards achieving this goal, experimental studies have defined adaptive mechanism by which oxygen homeostasis is maintained during acute anaemia. The mechanisms include: (1) effective sensing of anaemia-induced tissue hypoxia; (2) adaptive cardiovascular responses to maintain adequate tissue oxygen delivery; (3) heterogeneity of organ-specific oxygen delivery to preferentially sustain vital organs which are essential for acute survival (heart and brain); (4) evidence of increased vital organ injury with interruption of cardiovascular responses to anaemia and (5) evidence of activation of adaptive cellular responses to maintain oxygen homeostasis and support survival during acute anaemia. Understanding these mechanisms may allow us to define treatment thresholds and novel treatment strategies for acute anaemia based on biological markers of tissue hypoxia. The overall goal of these approaches is to improve patient outcomes, including event-free perioperative survival. Copyright © 2012 Elsevier Ltd. All rights reserved.

Severe pulmonary edema following hyperbaric oxygen therapy for acute carbon monoxide poisoning: a case report and clinical experience.

PubMed

Fan, Danfeng; Lv, Yan; Hu, Huijun; Pan, Shuyi

2017-01-01

Pulmonary edema following hyperbaric oxygen (HBO₂) therapy is a rare clinical phenomenon. This case report describes such a patient - a 56-year-old woman who suffered from severe pulmonary edema after HBO₂ therapy for carbon monoxide (CO) poisoning. Patient experienced ecphysesis and dyspnea suddenly after HBO₂ therapy (100% oxygen at 0.25 MPa, for 60 minutes with a five-minute air break and decompression at 0.01 MPa/minute). Post therapy her heart rate (HR), blood pressure (BP), respiratory rate (RR) and oxygen saturation (SO₂) were 140 bpm, 60/40 mmHg, 38 bpm and 84%, respectively. Diagnoses of acute pulmonary edema and shock were made. Various treatments including antishock, tracheal intubation, mechanical ventilation for respiratory support, a diuretic, dexamethasone, asthma relief, and acidosis correction were administered. Pulmonary computed tomography (CT) indicated significant pulmonary edema. Due to active treatment, the patient showed gradual improvement. Pulmonary CT re-examination showed pulmonary edema markedly improved. At the two-year follow-up, the patient reported no abnormal mental or neurological symptoms. Acute pulmonary edema is rare but can lead to serious side effects of HBO₂ therapy in patients with severe acute CO poisoning. This complication must be must considered when administering HBO₂ therapy to patients with severe CO poisoning.

Significance of KATP channels, L-type Ca2+ channels and CYP450-4A enzymes in oxygen sensing in mouse cremaster muscle arterioles In vivo

PubMed Central

2013-01-01

Background ATP-sensitive K+ channels (KATP channels), NO, prostaglandins, 20-HETE and L-type Ca2+ channels have all been suggested to be involved in oxygen sensing in skeletal muscle arterioles, but the role of the individual mechanisms remain controversial. We aimed to establish the importance of these mechanisms for oxygen sensing in arterioles in an in vivo model of metabolically active skeletal muscle. For this purpose we utilized the exteriorized cremaster muscle of anesthetized mice, in which the cremaster muscle was exposed to controlled perturbation of tissue PO2. Results Change from “high” oxygen tension (PO2 = 153.4 ± 3.4 mmHg) to “low” oxygen tension (PO2 = 13.8 ± 1.3 mmHg) dilated cremaster muscle arterioles from 11.0 ± 0.4 μm to 32.9 ± 0.9 μm (n = 28, P < 0.05). Glibenclamide (KATP channel blocker) caused maximal vasoconstriction, and abolished the dilation to low oxygen, whereas the KATP channel opener cromakalim caused maximal dilation and prevented the constriction to high oxygen. When adding cromakalim on top of glibenclamide or vice versa, the reactivity to oxygen was gradually restored. Inhibition of L-type Ca2+ channels using 3 μM nifedipine did not fully block basal tone in the arterioles, but rendered them unresponsive to changes in PO2. Inhibition of the CYP450-4A enzyme using DDMS blocked vasoconstriction to an increase in PO2, but had no effect on dilation to low PO2. Conclusions We conclude that: 1) L-type Ca2+ channels are central to oxygen sensing, 2) KATP channels are permissive for the arteriolar response to oxygen, but are not directly involved in the oxygen sensing mechanism and 3) CYP450-4A mediated 20-HETE production is involved in vasoconstriction to high PO2. PMID:23663730

Mechanical ventilation management during extracorporeal membrane oxygenation for acute respiratory distress syndrome: a retrospective international multicenter study.

PubMed

Schmidt, Matthieu; Stewart, Claire; Bailey, Michael; Nieszkowska, Ania; Kelly, Joshua; Murphy, Lorna; Pilcher, David; Cooper, D James; Scheinkestel, Carlos; Pellegrino, Vincent; Forrest, Paul; Combes, Alain; Hodgson, Carol

2015-03-01

To describe mechanical ventilation settings in adult patients treated for an acute respiratory distress syndrome with extracorporeal membrane oxygenation and assess the potential impact of mechanical ventilation settings on ICU mortality. Retrospective observational study. Three international high-volume extracorporeal membrane oxygenation centers. A total of 168 patients treated with extracorporeal membrane oxygenation for severe acute respiratory distress syndrome from January 2007 to January 2013. We analyzed the association between mechanical ventilation settings (i.e. plateau pressure, tidal volume, and positive end-expiratory pressure) on ICU mortality using multivariable logistic regression model and Cox-proportional hazards model. We obtained detailed demographic, clinical, daily mechanical ventilation settings and ICU outcome data. One hundred sixty-eight patients (41 ± 14 years old; PaO2/FIO2 67 ± 19 mm Hg) fulfilled our inclusion criteria. Median duration of extracorporeal membrane oxygenation and ICU stay were 10 days (6-18 d) and 28 days (16-42 d), respectively. Lower positive end-expiratory pressure levels and significantly lower plateau pressures during extracorporeal membrane oxygenation were used in the French center than in both Australian centers (23.9 ± 1.4 vs 27.6 ± 3.7 and 27.8 ± 3.6; p < 0.0001). Overall ICU mortality was 29%. Lower positive end-expiratory pressure levels (until day 7) and lower delivered tidal volume after 3 days on extracorporeal membrane oxygenation were associated with significantly higher mortality (p < 0.05). In multivariate analysis, higher positive end-expiratory pressure levels during the first 3 days of extracorporeal membrane oxygenation support were associated with lower mortality (odds ratio, 0.75; 95% CI, 0.64-0.88; p = 0.0006). Other independent predictors of ICU mortality included time between ICU admission and extracorporeal membrane oxygenation initiation, plateau pressure greater than 30 cm H2O before

Effect of Noninvasive Ventilation vs Oxygen Therapy on Mortality Among Immunocompromised Patients With Acute Respiratory Failure: A Randomized Clinical Trial.

PubMed

Lemiale, Virginie; Mokart, Djamel; Resche-Rigon, Matthieu; Pène, Frédéric; Mayaux, Julien; Faucher, Etienne; Nyunga, Martine; Girault, Christophe; Perez, Pierre; Guitton, Christophe; Ekpe, Kenneth; Kouatchet, Achille; Théodose, Igor; Benoit, Dominique; Canet, Emmanuel; Barbier, François; Rabbat, Antoine; Bruneel, Fabrice; Vincent, Francois; Klouche, Kada; Loay, Kontar; Mariotte, Eric; Bouadma, Lila; Moreau, Anne-Sophie; Seguin, Amélie; Meert, Anne-Pascale; Reignier, Jean; Papazian, Laurent; Mehzari, Ilham; Cohen, Yves; Schenck, Maleka; Hamidfar, Rebecca; Darmon, Michael; Demoule, Alexandre; Chevret, Sylvie; Azoulay, Elie

2015-10-27

Noninvasive ventilation has been recommended to decrease mortality among immunocompromised patients with hypoxemic acute respiratory failure. However, its effectiveness for this indication remains unclear. To determine whether early noninvasive ventilation improved survival in immunocompromised patients with nonhypercapnic acute hypoxemic respiratory failure. Multicenter randomized trial conducted among 374 critically ill immunocompromised patients, of whom 317 (84.7%) were receiving treatment for hematologic malignancies or solid tumors, at 28 intensive care units (ICUs) in France and Belgium between August 12, 2013, and January 2, 2015. Patients were randomly assigned to early noninvasive ventilation (n = 191) or oxygen therapy alone (n = 183). The primary outcome was day-28 mortality. Secondary outcomes were intubation, Sequential Organ Failure Assessment score on day 3, ICU-acquired infections, duration of mechanical ventilation, and ICU length of stay. At randomization, median oxygen flow was 9 L/min (interquartile range, 5-15) in the noninvasive ventilation group and 9 L/min (interquartile range, 6-15) in the oxygen group. All patients in the noninvasive ventilation group received the first noninvasive ventilation session immediately after randomization. On day 28 after randomization, 46 deaths (24.1%) had occurred in the noninvasive ventilation group vs 50 (27.3%) in the oxygen group (absolute difference, -3.2 [95% CI, -12.1 to 5.6]; P = .47). Oxygenation failure occurred in 155 patients overall (41.4%), 73 (38.2%) in the noninvasive ventilation group and 82 (44.8%) in the oxygen group (absolute difference, -6.6 [95% CI, -16.6 to 3.4]; P = .20). There were no significant differences in ICU-acquired infections, duration of mechanical ventilation, or lengths of ICU or hospital stays. Among immunocompromised patients admitted to the ICU with hypoxemic acute respiratory failure, early noninvasive ventilation compared with oxygen therapy alone did

Rapid response oxygen-sensing nanofibers

PubMed Central

Xue, Ruipeng; Behera, Prajna; Viapiano, Mariano S.; Lannutti, John J.

2014-01-01

Molecular oxygen has profound effects on cell and tissue viability. Relevant sensor forms that can rapidly determine dissolved oxygen levels under biologically relevant conditions provide critical metabolic information. Using 0.5 μm diameter electrospun polycaprolactone (PCL) fiber containing an oxygen-sensitive probe, tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride, we observed a response time of 0.9±0.12 seconds – 4–10 times faster than previous reports – while the t95 for the corresponding film was more than two orders of magnitude greater. Interestingly, the response and recovery times of slightly larger diameter PCL fibers were 1.79±0.23 s and 2.29±0.13 s, respectively, while the recovery time was not statistically different likely due to the more limited interactions of nitrogen with the polymer matrix. A more than 10-fold increase in PCL fiber diameter reduces oxygen sensitivity while having minor effects on response time; conversely, decreases in fiber diameter to less than 0.5 μm would likely decrease response times even further. In addition, a 50°C heat treatment of the electrospun fiber resulted in both increased Stern-Volmer slope and linearity likely due to secondary recrystallization that further homogenized the probe microenvironment. At exposure times up to 3600 s in length, photobleaching was observed but was largely eliminated by the use of either polyethersulfone (PES) or a PES-PCL core-shell composition. However, this resulted in 2- and 3-fold slower response times. Finally, even the non-core shell compositions containing the Ru oxygen probe result in no apparent cytotoxicity in representative glioblastoma cell populations. PMID:23706233

Regulation of endocytosis via the oxygen-sensing pathway.

PubMed

Wang, Yi; Roche, Olga; Yan, Mathew S; Finak, Greg; Evans, Andrew J; Metcalf, Julie L; Hast, Bridgid E; Hanna, Sara C; Wondergem, Bill; Furge, Kyle A; Irwin, Meredith S; Kim, William Y; Teh, Bin T; Grinstein, Sergio; Park, Morag; Marsden, Philip A; Ohh, Michael

2009-03-01

Tumor hypoxia is associated with disease progression, resistance to conventional cancer therapies and poor prognosis. Hypoxia, by largely unknown mechanisms, leads to deregulated accumulation of and signaling via receptor tyrosine kinases (RTKs) that are critical for driving oncogenesis. Here, we show that hypoxia or loss of von Hippel-Lindau protein--the principal negative regulator of hypoxia-inducible factor (HIF)--prolongs the activation of epidermal growth factor receptor that is attributable to lengthened receptor half-life and retention in the endocytic pathway. The deceleration in endocytosis is due to the attenuation of Rab5-mediated early endosome fusion via HIF-dependent downregulation of a critical Rab5 effector, rabaptin-5, at the level of transcription. Primary kidney and breast tumors with strong hypoxic signatures show significantly lower expression of rabaptin-5 RNA and protein. These findings reveal a general role of the oxygen-sensing pathway in endocytosis and support a model in which tumor hypoxia or oncogenic activation of HIF prolongs RTK-mediated signaling by delaying endocytosis-mediated deactivation of receptors.

Regional brain blood flow and cerebral hemispheric oxygen consumption during acute hypoxaemia in the llama fetus

PubMed Central

Llanos, Aníbal J; Riquelme, Raquel A; Sanhueza, Emilia M; Herrera, Emilio; Cabello, Gertrudis; Giussani, Dino A; Parer, Julian T

2002-01-01

Unlike fetal animals of lowland species, the llama fetus does not increase its cerebral blood flow during an episode of acute hypoxaemia. This study tested the hypothesis that the fetal llama brain maintains cerebral hemispheric O2 consumption by increasing cerebral O2 extraction rather than decreasing cerebral oxygen utilisation during acute hypoxaemia. Six llama fetuses were surgically instrumented under general anaesthesia at 217 days of gestation (term ca 350 days) with vascular and amniotic catheters in order to carry out cardiorespiratory studies. Following a control period of 1 h, the llama fetuses underwent 3 × 20 min episodes of progressive hypoxaemia, induced by maternal inhalational hypoxia. During basal conditions and during each of the 20 min of hypoxaemia, fetal cerebral blood flow was measured with radioactive microspheres, cerebral oxygen extraction was calculated, and fetal cerebral hemispheric O2 consumption was determined by the modified Fick principle. During hypoxaemia, fetal arterial O2 tension and fetal pH decreased progressively from 24 ± 1 to 20 ± 1 Torr and from 7.36 ± 0.01 to 7.33 ± 0.01, respectively, during the first 20 min episode, to 16 ± 1 Torr and 7.25 ± 0.05 during the second 20 min episode and to 14 ± 1 Torr and 7.21 ± 0.04 during the final 20 min episode. Fetal arterial partial pressure of CO2 (Pa,CO2, 42 ± 2 Torr) remained unaltered from baseline throughout the experiment. Fetal cerebral hemispheric blood flow and cerebral hemispheric oxygen extraction were unaltered from baseline during progressive hypoxaemia. In contrast, a progressive fall in fetal cerebral hemispheric oxygen consumption occurred during the hypoxaemic challenge. In conclusion, these data do not support the hypothesis that the fetal llama brain maintains cerebral hemispheric O2 consumption by increasing cerebral hemispheric O2 extraction. Rather, the data show that in the llama fetus, a reduction in cerebral hemispheric metabolism occurs during acute

Lack of effect of moderate hypothermia on brain tissue oxygenation after acute intracranial hypertension in pigs.

PubMed

Bao, Ying-Hui; Liang, Yu-Min; Gao, Guo-Yi; Jiang, Ji-Yao

2010-02-01

In this study, we explored the effect of moderate hypothermia on brain tissue oxygenation following acute intracranial hypertension in micropigs. Twenty healthy juvenile micropigs weighting 4-6 kg were randomized into two groups: a normothermia group (n = 10) and a moderate hypothermia group (n = 10). The animals were intravenously anesthetized with propofol (4 mg/kg), an endotracheal tube was inserted, and mechanical ventilation was begun. Autologous arterial blood was injected into the left frontal lobe to establish acute intracerebral hematoma and intracranial hypertension (intracranial pressure [ICP] >40 mm Hg) in all animals. Cooling was initiated at 30 min after injection of the blood, and was achieved via the use of an ice bath and ice packs. In the hypothermia group, the brain temperature decreased to 33-34 degrees C. Brain temperature was maintained at 37 +/- 0.3 degrees C in the normothermia group. The ICP, cerebral perfusion pressure (CPP), brain tissue oxygen pressure (P(br)O(2)), brain tissue carbon dioxide pressure (P(br)CO(2)), and brain tissue pH value (pH(br)) were continuously monitored for 3 h in all animals. Compared to normothermia group, ICP values significantly decreased and CPP markedly improved in the hypothermia group (p < 0.05). Further, pH(br) also markedly increased and P(br)CO(2) decreased significantly in the hypothermia group (p < 0.05). However, P(br)O(2) did not statistically significantly improve in the hypothermia group (p > 0.05). In sum, moderate hypothermia significantly decreased ICP, reduced P(br)CO(2), and increased pH(br) values, but did not improve cerebral oxygenation following acute intracranial hypertension.

Oxygen sensing PLIM together with FLIM of intrinsic cellular fluorophores for metabolic mapping

NASA Astrophysics Data System (ADS)

Kalinina, Sviatlana; Schaefer, Patrick; Breymayer, Jasmin; Bisinger, Dominik; Chakrabortty, Sabyasachi; Rueck, Angelika

2018-02-01

Otical imaging techniques based on time correlated single photon counting (TCSPC) has found wide applications in medicine and biology. Non-invasive and information-rich fluorescence lifetime imaging microscopy (FLIM) is successfully used for monitoring fluorescent intrinsic metabolic coenzymes as NAD(P)H (nicotinamide adenine dinucleotide (phosphate)) and FAD+ (flavin adenine dinucleotide) in living cells and tissues. The ratio between proteinbound and free coenzymes gives an information about the balance between oxidative phosphorylation and glycolysis in the cells. The changes of the ratio reflects major cellular disorders. A correlation exists between metabolic activity, redox ratio and fluorescence lifetime during stem cell differentiation, neurodegenerative diseases, and carcinogenesis. A multichannel FLIM detection system was designed for monitoring the redox state of NAD(P)H and FAD+ and other intrinsic fluorophores as protoporphyrin IX. In addition, the unique upgrade is useful to perform FLIM and PLIM (phosphorescence lifetime imaging microscopy) simultaneously. PLIM is a promising method to investigate oxygen sensing in biomedical samples. In detail, the oxygen-dependent quenching of phosphorescence of some compounds as transition metal complexes enables measuring of oxygen partial pressure (pO2). Using a two-channel FLIM/PLIM system we monitored intrinsic pO2 by PLIM simultaneously with NAD(P)H by FLIM providing complex metabolic and redox imaging of living cells. Physico-chemical properties of oxygen sensitive probes define certain parameters including their localisation. We present results of some ruthenium based complexes including those specifically bound to mitochondria.

Guinea Pig Oxygen-Sensing and Carotid Body Functional Properties

PubMed Central

Gonzalez-Obeso, Elvira; Docio, Inmaculada; Olea, Elena; Cogolludo, Angel; Obeso, Ana; Rocher, Asuncion; Gomez-Niño, Angela

2017-01-01

Mammals have developed different mechanisms to maintain oxygen supply to cells in response to hypoxia. One of those mechanisms, the carotid body (CB) chemoreceptors, is able to detect physiological hypoxia and generate homeostatic reflex responses, mainly ventilatory and cardiovascular. It has been reported that guinea pigs, originally from the Andes, have a reduced ventilatory response to hypoxia compared to other mammals, implying that CB are not completely functional, which has been related to genetically/epigenetically determined poor hypoxia-driven CB reflex. This study was performed to check the guinea pig CB response to hypoxia compared to the well-known rat hypoxic response. These experiments have explored ventilatory parameters breathing different gases mixtures, cardiovascular responses to acute hypoxia, in vitro CB response to hypoxia and other stimuli and isolated guinea pig chemoreceptor cells properties. Our findings show that guinea pigs are hypotensive and have lower arterial pO2 than rats, probably related to a low sympathetic tone and high hemoglobin affinity. Those characteristics could represent a higher tolerance to hypoxic environment than other rodents. We also find that although CB are hypo-functional not showing chronic hypoxia sensitization, a small percentage of isolated carotid body chemoreceptor cells contain tyrosine hydroxylase enzyme and voltage-dependent K+ currents and therefore can be depolarized. However hypoxia does not modify intracellular Ca2+ levels or catecholamine secretion. Guinea pigs are able to hyperventilate only in response to intense acute hypoxic stimulus, but hypercapnic response is similar to rats. Whether other brain areas are also activated by hypoxia in guinea pigs remains to be studied. PMID:28533756

Guinea Pig Oxygen-Sensing and Carotid Body Functional Properties.

PubMed

Gonzalez-Obeso, Elvira; Docio, Inmaculada; Olea, Elena; Cogolludo, Angel; Obeso, Ana; Rocher, Asuncion; Gomez-Niño, Angela

2017-01-01

Mammals have developed different mechanisms to maintain oxygen supply to cells in response to hypoxia. One of those mechanisms, the carotid body (CB) chemoreceptors, is able to detect physiological hypoxia and generate homeostatic reflex responses, mainly ventilatory and cardiovascular. It has been reported that guinea pigs, originally from the Andes, have a reduced ventilatory response to hypoxia compared to other mammals, implying that CB are not completely functional, which has been related to genetically/epigenetically determined poor hypoxia-driven CB reflex. This study was performed to check the guinea pig CB response to hypoxia compared to the well-known rat hypoxic response. These experiments have explored ventilatory parameters breathing different gases mixtures, cardiovascular responses to acute hypoxia, in vitro CB response to hypoxia and other stimuli and isolated guinea pig chemoreceptor cells properties. Our findings show that guinea pigs are hypotensive and have lower arterial pO 2 than rats, probably related to a low sympathetic tone and high hemoglobin affinity. Those characteristics could represent a higher tolerance to hypoxic environment than other rodents. We also find that although CB are hypo-functional not showing chronic hypoxia sensitization, a small percentage of isolated carotid body chemoreceptor cells contain tyrosine hydroxylase enzyme and voltage-dependent K + currents and therefore can be depolarized. However hypoxia does not modify intracellular Ca 2+ levels or catecholamine secretion. Guinea pigs are able to hyperventilate only in response to intense acute hypoxic stimulus, but hypercapnic response is similar to rats. Whether other brain areas are also activated by hypoxia in guinea pigs remains to be studied.

Efficacy of high-flow oxygen by nasal cannula with active humidification in a patient with acute respiratory failure of neuromuscular origin.

PubMed

Díaz-Lobato, Salvador; Folgado, Miguel Angel; Chapa, Angel; Mayoralas Alises, Sagrario

2013-12-01

The treatment of choice for patients with respiratory failure of neuromuscular origin, especially in patients with hypercapnic respiratory acidosis, is noninvasive ventilation (NIV). Endotracheal intubation and invasive ventilation are indicated for patients with severe respiratory compromise or failure of NIV. In recent years, high-flow oxygen therapy and active humidification devices have been introduced, and emerging evidence suggests that high-flow oxygen may be effective in various clinical settings, such as acute respiratory failure, after cardiac surgery, during sedation and analgesia, in acute heart failure, in hypoxemic respiratory distress, in do-not-intubate patients, in patients with chronic cough and copious secretions, pulmonary fibrosis, or cancer, in critical areas and the emergency department. We report on a patient with amyotrophic lateral sclerosis who arrived at the emergency department with acute hypercapnic respiratory failure. She did not tolerate NIV and refused intubation, but was treated successfully with heated, humidified oxygen via high-flow nasal cannula. Arterial blood analysis after an hour on high-flow nasal cannula showed improved pH, P(aCO2), and awareness. The respiratory acidosis was corrected, and she was discharged after 5 days of hospitalization. Her response to high-flow nasal cannula was similar to that expected with NIV. We discuss the mechanisms of action of heated, humidified high-flow oxygen therapy.

High-flow nasal oxygen vs. standard oxygen therapy in immunocompromised patients with acute respiratory failure: study protocol for a randomized controlled trial.

PubMed

Azoulay, Elie; Lemiale, Virginie; Mokart, Djamel; Nseir, Saad; Argaud, Laurent; Pène, Frédéric; Kontar, Loay; Bruneel, Fabrice; Klouche, Kada; Barbier, François; Reignier, Jean; Stoclin, Anabelle; Louis, Guillaume; Constantin, Jean-Michel; Mayaux, Julien; Wallet, Florent; Kouatchet, Achille; Peigne, Vincent; Perez, Pierre; Girault, Christophe; Jaber, Samir; Oziel, Johanna; Nyunga, Martine; Terzi, Nicolas; Bouadma, Lila; Lebert, Christine; Lautrette, Alexandre; Bigé, Naike; Raphalen, Jean-Herlé; Papazian, Laurent; Rabbat, Antoine; Darmon, Michael; Chevret, Sylvie; Demoule, Alexandre

2018-03-05

Acute respiratory failure (ARF) is the leading reason for intensive care unit (ICU) admission in immunocompromised patients. High-flow nasal oxygen (HFNO) therapy is an alternative to standard oxygen. By providing warmed and humidified gas, HFNO allows the delivery of higher flow rates via nasal cannula devices, with FiO 2 values of nearly 100%. Benefits include alleviation of dyspnea and discomfort, decreased respiratory distress and decreased mortality in unselected patients with acute hypoxemic respiratory failure. However, in preliminary reports, HFNO benefits are controversial in immunocompromised patients in whom it has never been properly evaluated. This is a multicenter, open-label, randomized controlled superiority trial in 30 intensive care units, part of the Groupe de Recherche Respiratoire en Réanimation Onco-Hématologique (GRRR-OH). Inclusion criteria will be: (1) adults, (2) known immunosuppression, (3) ARF, (4) oxygen therapy ≥ 6 L/min, (5) written informed consent from patient or proxy. Exclusion criteria will be: (1) imminent death (moribund patient), (2) no informed consent, (3) hypercapnia (PaCO 2 ≥ 50 mmHg), (4) isolated cardiogenic pulmonary edema, (5) pregnancy or breastfeeding, (6) anatomical factors precluding insertion of a nasal cannula, (7) no coverage by the French statutory healthcare insurance system, and (8) post-surgical setting from day 1 to day 6 (patients with ARF occurring after day 6 of surgery can be included). The primary outcome measure is day-28 mortality. Secondary outcomes are intubation rate, comfort, dyspnea, respiratory rate, oxygenation, ICU length of stay, and ICU-acquired infections. Based on an expected 30% mortality rate in the standard oxygen group, and 20% in the HFNO group, error rate set at 5%, and a statistical power at 90%, 389 patients are required in each treatment group (778 patients overall). Recruitment period is estimated at 30 months, with 28 days of additional follow-up for the last included

Acute stress enhances learning and memory by activating acid-sensing ion channels in rats.

PubMed

Ye, Shunjie; Yang, Rong; Xiong, Qiuju; Yang, Youhua; Zhou, Lianying; Gong, Yeli; Li, Changlei; Ding, Zhenhan; Ye, Guohai; Xiong, Zhe

2018-04-15

Acute stress has been shown to enhance learning and memory ability, predominantly through the action of corticosteroid stress hormones. However, the valuable targets for promoting learning and memory induced by acute stress and the underlying molecular mechanisms remain unclear. Acid-sensing ion channels (ASICs) play an important role in central neuronal systems and involves in depression, synaptic plasticity and learning and memory. In the current study, we used a combination of electrophysiological and behavioral approaches in an effort to explore the effects of acute stress on ASICs. We found that corticosterone (CORT) induced by acute stress caused a potentiation of ASICs current via glucocorticoid receptors (GRs) not mineralocorticoid receptors (MRs). Meanwhile, CORT did not produce an increase of ASICs current by pretreated with GF109203X, an antagonist of protein kinase C (PKC), whereas CORT did result in a markedly enhancement of ASICs current by bryostatin 1, an agonist of PKC, suggesting that potentiation of ASICs function may be depended on PKC activating. More importantly, an antagonist of ASICs, amiloride (10 μM) reduced the performance of learning and memory induced by acute stress, which is further suggesting that ASICs as the key components involves in cognitive processes induced by acute stress. These results indicate that acute stress causes the enhancement of ASICs function by activating PKC signaling pathway, which leads to potentiated learning and memory. Copyright © 2018 Elsevier Inc. All rights reserved.

The Association of Early Blood Oxygenation with Child Development in Preterm Infants with Acute Respiratory Disorders

PubMed Central

Smith, Karen E.; Keeney, Susan; Zhang, Lifang; Perez-Polo, Regino; Rassin, David K.

2008-01-01

The potential negative impact of early blood oxygenation on development of specific cognitive and motor outcomes in children born at very low birth weight (VLBW; 1000 − 1500g) has not been examined even though these infants are exposed to varying durations and amounts of oxygen as part of their neonatal care. While this is the largest group of preterm infants, they receive much less research attention than extremely low birth weight infants (ELBW < 1000g). Although neonatologists are questioning the routine use of oxygen therapy for all neonates, research has focused primarily on the more medically fragile ELBW infants. To date there are no systematic studies available to guide decision making for oxygen supplementation for a large segment of the preterm infant population. The aim of the present study was to determine if there is an association between blood oxygenation in the first four hours of life and specific cognitive and motor skills in preterm infants with acute respiratory disorders but no severe intracranial insult using a selected cohort from a longitudinal study children recruited in 1991 and 1992 designed to examine the role of biological immaturity as defined by gestational age and parenting in development. From this cohort, 55 children had acute respiratory disorders without severe intracranial insult. Of these, 35 children had at least one partial pressure of oxygen obtained from arterial blood (PaO2) during the first four hours of life as part of their clinical care. Higher early PaO2 values were associated with lower impulse control and attention skills in the elementary school age period. Models that examined for relations between PaO2 values that also included birth weight and parenting quality across the first year of life revealed that higher PaO2 remained associated with impulse control but not attention skills. Birth weight was not associated with any outcomes. These results suggest that hyperoxia may be a risk factor for developmental

Oxygen control of breathing by an olfactory receptor activated by lactate

PubMed Central

Chang, Andy J.; Ortega, Fabian E.; Riegler, Johannes; Madison, Daniel V.; Krasnow, Mark A.

2015-01-01

Summary Animals have evolved homeostatic responses to changes in oxygen availability that act on different time scales. Although the hypoxia-inducible factor (HIF) transcriptional pathway that controls long term responses to low oxygen (hypoxia) has been established1, the pathway that mediates acute responses to hypoxia in mammals is not well understood. Here we show that the olfactory receptor Olfr78 is highly and selectively expressed in oxygen-sensitive glomus cells of the carotid body, a chemosensory organ at the carotid artery bifurcation that monitors blood oxygen and stimulates breathing within seconds when oxygen declines2. Olfr78 mutants fail to increase ventilation in hypoxia but respond normally to hypercapnia. Glomus cells are present in normal numbers and appear structurally intact, but hypoxia-induced carotid body activity is diminished. Lactate, a metabolite that rapidly accumulates in hypoxia and induces hyperventilation3–6, activates Olfr78 in heterologous expression experiments, induces calcium transients in glomus cells, and stimulates carotid sinus nerve activity through Olfr78. We propose that in addition to its role in olfaction, Olfr78 acts as a hypoxia sensor in the breathing circuit by sensing lactate produced when oxygen levels decline. PMID:26560302

Growth and characterization of nanostructured CuO films via CBD approach for oxygen gas sensing

NASA Astrophysics Data System (ADS)

Nurfazliana, M. F.; Sahdan, M. Z.; Saim, H.

2017-01-01

Nanostructured copper oxide (CuO) films were grown on portable IDE circuit silicon-based by low-cost chemical bath deposition (CBD) technique at three different deposition times (3 h, 5 h and 7 h). The effect of deposition times on the morphological, structural, optical and sensing properties of the nanostructured films were investigated. From the morphological and structural properties, the nanostructured film deposited at 5 h was found to have homogenous surface of CuO nanowhiskers and high crystallinity with tenorite phase compared to 3 h and 7 h films. Besides, there is no heat treatment required in order to produce CuO nanostructures film with tenorite phase. The sensing response (resistance changes) of as-synthesized films to concentration of oxygen (O2) gas also was compared. Film resistance of CuO nanostructures was studied in an environment of dry air loaded (gas sensor chamber) with 30 % of O2 gas. The results revealed that the deposition time causes significant effect on the sensing performance of nanostructured CuO to O2 gas.

Beneficial effects of warmed humidified oxygen combined with nebulized albuterol and ipratropium in pediatric patients with acute exacerbation of asthma in winter months.

PubMed

Nibhanipudi, Kumara; Hassen, Getaw Worku; Smith, Arthur

2009-11-01

The objective of this study was to determine whether a combination of nebulized albuterol and ipratropium with warmed humidified oxygen would be more beneficial when compared to the same combination with humidified oxygen at room temperature. Albuterol alone was tested in the same settings. All patients between 6 and 17 years of age who presented to a pediatric emergency department in the winter months with acute exacerbation of bronchial asthma were given a combination of nebulized albuterol and ipratropium with warmed or room temperature humidified oxygen. Peak flow was measured before and after the treatment. Sixty patients were enrolled in the study, with 15 subjects in each group. The mean increase in peak flow in the albuterol-ipratropium with warm humidified oxygen group was 52.6, and in the albuterol-ipratropium with humidified oxygen at room temperature group, it was 26.2. The results of the albuterol with warmed humidified oxygen and with humidified oxygen at room temperature groups were 20.6 and 34.3, respectively. The differences between the groups were statistically significant. Our study shows that warmed humidified oxygen given along with the combination of nebulized albuterol and ipratropium is more beneficial for pediatric patients having an acute exacerbation of bronchial asthma in the winter months when compared to nebulized albuterol alone with warmed humidified oxygen, nebulized albuterol alone with room temperature humidified oxygen, or a combination of nebulized albuterol and ipratropium with room temperature humidified oxygen.

Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration.

PubMed

Sheard, Michael A; Ghent, Matthew V; Cabral, Daniel J; Lee, Joanne C; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q; Kang, Min H; Sposto, Richard; Asgharzadeh, Shahab; Reynolds, C Patrick

2015-05-15

Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival, expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. Copyright © 2015. Published by Elsevier Inc.

Variability in hyperbaric oxygen treatment for acute carbon monoxide poisoning.

PubMed

Byrne, Brendan T; Lu, Jenny J; Valento, Matthew; Bryant, Sean M

2012-01-01

In patients with acute carbon monoxide (CO) poisoning, we have noted wide clinical variability in both criteria for hyperbaric oxygen (HBO2) treatment as well as HBO2 treatment regimens. Our aim was to survey Midwest hyperbaric centers for insight into specific criteria and protocols for treating acute CO toxicity with HBO2. Hyperbaric centers were identified from the published list of the Undersea and Hyperbaric Medical Society. Ninety-three centers from nine Midwestern states were contacted via telephone. A standard script was used to minimize surveyor bias. Thirty centers that treat CO poisonings were identified. One did not participate in the study. Nineteen reported a specific level of carboxyhemoglobin (COHb) that served as an independent indication for initiation of HBO2 treatment. Four centers used the COHb level as the exclusive indication for HBO2 treatment. Ten centers relied solely on reported symptoms, while the remaining centers used a combination of symptoms plus COHb levels. There were 19 separate treatment protocols. No uniform practice for either the initiation or implementation of HBO2 therapy for CO poisoning exists among U.S. Midwest hyperbaric centers responding to a survey. We see opportunity for specific targeted educational programs as well as further study.

Oxygen decline in biotesting of environmental samples--is there a need for consideration in the acute zebrafish embryo assay?

PubMed

Küster, Eberhard; Altenburger, Rolf

2008-12-01

Environmental samples such as groundwater, sediment pore water, native or freeze dried sediments may be difficult to analyze for toxic effects with organismic aquatic bioassays. These samples might evoke low oxygen concentration or oxygen depletion during the test. The toxicity assessment could thus be confounded by low oxygen concentrations. The acute zebrafish embryo assay was used to analyze the influence of oxygen deficit on the embryonic development in the first 48 h post fertilization. Embryos were exposed to varying oxygen concentrations ranging from <30 to >80% oxygen saturation of water. A clear concentration dependent retardation of fish embryo development was observed. Because of a retarded development toxic thresholds of environmental samples which might include substances slowing down the development will be altered. For the purpose of identification of critical contaminants in complex environmental samples, it is proposed to actively aerate environmental samples which are likely to be oxygen depleted during the duration of the zebrafish embryo bioassay. 2008 Wiley Periodicals, Inc.

Oxygen sensing in intestinal mucosal inflammation.

PubMed

Flück, Katharina; Fandrey, Joachim

2016-01-01

Hypoxia is a hallmark of chronically inflamed tissue. Hypoxia develops from vascular dysfunction and increased oxygen consumption by infiltrating leukocytes. With respect to inflammatory bowel disease (IBD), hypoxia is likely to be of particular importance: Impairment of the intestinal barrier during IBD allows anoxia from the lumen of the gut to spread to formerly normoxic tissue. In addition, disturbed perfusion of inflamed tissue and a higher oxygen demand of infiltrating immune cells lead to low oxygen levels in inflamed mucosal tissue. Here, cells become hypoxic and must now adapt to this condition. The hypoxia inducible factor (HIF)-1 complex is a key transcription factor for cellular adaption to low oxygen tension. HIF-1 is a heterodimer formed by two subunits: HIF-α (either HIF-1α or HIF-2α) and HIF-1β. Under normoxic conditions, hydroxylation of the HIF-α subunit by specific oxygen-dependent prolyl hydroxylases (PHDs) leads to ubiquitin proteasome-dependent degradation. Under hypoxic conditions, however, PHD activity is inhibited; thus, HIF-α can translocate into the nucleus, dimerize with HIF-1β, and bind to hypoxia-responsive elements of HIF-1 target genes. So far, most studies have addressed the function of HIF-1α in intestinal epithelial cells and the effect of HIF stabilization by PHD inhibitors in murine models of colitis. Furthermore, the role of HIF-1α in immune cells becomes more and more important as T cells or dendritic cells for which HIF-1 is of critical importance are highly involved in the pathogenesis of IBD. This review will summarize the function of HIF-1α and the therapeutic prospects for targeting the HIF pathway in intestinal mucosal inflammation.

Economics of Inhaled Oxygen Use as an Acute Therapy for Cluster Headache in the United States of America.

PubMed

O'Brien, Megan; Ford, Janet H; Aurora, Sheena K; Govindan, Sriram; Tepper, Deborah E; Tepper, Stewart J

2017-10-01

Cluster headache (CH) is a primary headache disorder associated with low levels of diagnosis and high unmet medical need. The pain attacks, associated anxiety, and fear in anticipation of the attacks are extremely debilitating to a patient with CH. For acute therapy, treatment guidelines recommend inhalation of high flow oxygen during the period of an attack. However, the use of oxygen for treatment of CH remains largely underutilized. The objectives of the study, which covered each of the US states, were to map the current market landscape of medical grade oxygen for use in CH and to develop a cost simulator based on a patient's needs and geography. Desk research was undertaken to obtain price lists and product catalogs from wholesale and retail suppliers of medical grade oxygen across all US states. Base case scenarios for chronic and episodic forms of CH were assumed. A cost simulator was used to calculate the cost of oxygen use using inputs including the state in USA, tank size and price, exacerbations per year, duration of exacerbation, attacks per day, flow rate and duration of flow. Information was also collected to determine if healthcare insurers covered the costs of home oxygen use for CH. Out of the 42 US states where pricing information of medical grade oxygen was available from suppliers, in 38 states the annual cost of high-flow oxygen for a patient with episodic CH was estimated to be <$1000. In 39 states, the annual cost of high-flow oxygen for a patient with chronic CH was estimated to be <$5000. Most of the home oxygen suppliers were familiar with CH and stocked the special non-rebreather masks and regulators necessary for this condition. It was found that many of the private commercial healthcare insurance providers reimbursed the cost of oxygen use for CH. However, the US Centers for Medicare and Medicaid Services (CMS) maintains there is insufficient evidence for coverage and continues to deny coverage for US Medicare and Medicaid patients

Oxygen Sensing, Hypoxia Tracing and in Vivo Imaging with Functional Metalloprobes for the Early Detection of Non-communicable Diseases

PubMed Central

Mirabello, Vincenzo; Cortezon-Tamarit, Fernando; Pascu, Sofia I.

2018-01-01

Hypoxia has been identified as one of the hallmarks of tumor environments and a prognosis factor in many cancers. The development of ideal chemical probes for imaging and sensing of hypoxia remains elusive. Crucial characteristics would include a measurable response to subtle variations of pO2 in living systems and an ability to accumulate only in the areas of interest (e.g., targeting hypoxia tissues) whilst exhibiting kinetic stabilities in vitro and in vivo. A sensitive probe would comprise platforms for applications in imaging and therapy for non-communicable diseases (NCDs) relying on sensitive detection of pO2. Just a handful of probes for the in vivo imaging of hypoxia [mainly using positron emission tomography (PET)] have reached the clinical research stage. Many chemical compounds, whilst presenting promising in vitro results as oxygen-sensing probes, are facing considerable disadvantages regarding their general application in vivo. The mechanisms of action of many hypoxia tracers have not been entirely rationalized, especially in the case of metallo-probes. An insight into the hypoxia selectivity mechanisms can allow an optimization of current imaging probes candidates and this will be explored hereby. The mechanistic understanding of the modes of action of coordination compounds under oxygen concentration gradients in living cells allows an expansion of the scope of compounds toward in vivo applications which, in turn, would help translate these into clinical applications. We summarize hereby some of the recent research efforts made toward the discovery of new oxygen sensing molecules having a metal-ligand core. We discuss their applications in vitro and/or in vivo, with an appreciation of a plethora of molecular imaging techniques (mainly reliant on nuclear medicine techniques) currently applied in the detection and tracing of hypoxia in the preclinical and clinical setups. The design of imaging/sensing probe for early-stage diagnosis would longer term

Oxygen sensing with an absolute optical sensor based on biluminescence (Conference Presentation)

NASA Astrophysics Data System (ADS)

Salas Redondo, Caterin; Reineke, Sebastian

2017-06-01

exciton dynamic range extended up to nine orders of magnitude between nanosecond-lifetime fluorescence and millisecond-lifetime phosphorescence. In this presentation, we will report on the oxygen sensing characteristics of this luminescent system compared to a benchmarked single state optical sensor. Such properties can be evaluated because of the sensitivity of the triplet state to oxygen and therefore, we investigate the dependence of the persistent phosphorescence on the oxygen content. Furthermore, we will address our efforts towards the potential integration of novel optical biluminescent sensing into organic electronics.

Preservation of high glycolytic phenotype by establishing new acute lymphoblastic leukemia cell lines at physiologic oxygen concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheard, Michael A., E-mail: msheard@chla.usc.edu; Ghent, Matthew V., E-mail: mattghent@gmail.com; Cabral, Daniel J., E-mail: dcabral14@gmail.com

2015-05-15

Cancer cells typically exhibit increased glycolysis and decreased mitochondrial oxidative phosphorylation, and they continue to exhibit some elevation in glycolysis even under aerobic conditions. However, it is unclear whether cancer cell lines employ a high level of glycolysis comparable to that of the original cancers from which they were derived, even if their culture conditions are changed to physiologically relevant oxygen concentrations. From three childhood acute lymphoblastic leukemia (ALL) patients we established three new pairs of cell lines in both atmospheric (20%) and physiologic (bone marrow level, 5%) oxygen concentrations. Cell lines established in 20% oxygen exhibited lower proliferation, survival,more » expression of glycolysis genes, glucose consumption, and lactate production. Interestingly, the effects of oxygen concentration used during cell line initiation were only partially reversible when established cell cultures were switched from one oxygen concentration to another for eight weeks. These observations indicate that ALL cell lines established at atmospheric oxygen concentration can exhibit relatively low levels of glycolysis and these levels are semi-permanent, suggesting that physiologic oxygen concentrations may be needed from the time of cell line initiation to preserve the high level of glycolysis commonly exhibited by leukemias in vivo. - Highlights: • Establishing new ALL cell lines in 5% oxygen resulted in higher glycolytic expression and function. • Establishing new ALL cell lines in 5% oxygen resulted in higher proliferation and lower cell death. • The divergent metabolic phenotypes selected in 5% and 20% oxygen are semi-permanent.« less

Blood oxygenation level-dependent MRI for assessment of renal oxygenation

PubMed Central

Neugarten, Joel; Golestaneh, Ladan

2014-01-01

Blood oxygen level-dependent magnetic resonance imaging (BOLD MRI) has recently emerged as an important noninvasive technique to assess intrarenal oxygenation under physiologic and pathophysiologic conditions. Although this tool represents a major addition to our armamentarium of methodologies to investigate the role of hypoxia in the pathogenesis of acute kidney injury and progressive chronic kidney disease, numerous technical limitations confound interpretation of data derived from this approach. BOLD MRI has been utilized to assess intrarenal oxygenation in numerous experimental models of kidney disease and in human subjects with diabetic and nondiabetic chronic kidney disease, acute kidney injury, renal allograft rejection, contrast-associated nephropathy, and obstructive uropathy. However, confidence in conclusions based on data derived from BOLD MRI measurements will require continuing advances and technical refinements in the use of this technique. PMID:25473304

Blood transfusion improves renal oxygenation and renal function in sepsis-induced acute kidney injury in rats.

PubMed

Zafrani, Lara; Ergin, Bulent; Kapucu, Aysegul; Ince, Can

2016-12-20

The effects of blood transfusion on renal microcirculation during sepsis are unknown. This study aimed to investigate the effect of blood transfusion on renal microvascular oxygenation and renal function during sepsis-induced acute kidney injury. Twenty-seven Wistar albino rats were randomized into four groups: a sham group (n = 6), a lipopolysaccharide (LPS) group (n = 7), a LPS group that received fluid resuscitation (n = 7), and a LPS group that received blood transfusion (n = 7). The mean arterial blood pressure, renal blood flow, and renal microvascular oxygenation within the kidney cortex were recorded. Acute kidney injury was assessed using the serum creatinine levels, metabolic cost, and histopathological lesions. Nitrosative stress (expression of endothelial (eNOS) and inducible nitric oxide synthase (iNOS)) within the kidney was assessed by immunohistochemistry. Hemoglobin levels, pH, serum lactate levels, and liver enzymes were measured. Fluid resuscitation and blood transfusion both significantly improved the mean arterial pressure and renal blood flow after LPS infusion. Renal microvascular oxygenation, serum creatinine levels, and tubular damage significantly improved in the LPS group that received blood transfusion compared to the group that received fluids. Moreover, the renal expression of eNOS was markedly suppressed under endotoxin challenge. Blood transfusion, but not fluid resuscitation, was able to restore the renal expression of eNOS. However, there were no significant differences in lactic acidosis or liver function between the two groups. Blood transfusion significantly improved renal function in endotoxemic rats. The specific beneficial effect of blood transfusion on the kidney could have been mediated in part by the improvements in renal microvascular oxygenation and sepsis-induced endothelial dysfunction via the restoration of eNOS expression within the kidney.

Oxygen in acute and chronic wound healing.

PubMed

Schreml, S; Szeimies, R M; Prantl, L; Karrer, S; Landthaler, M; Babilas, P

2010-08-01

Oxygen is a prerequisite for successful wound healing due to the increased demand for reparative processes such as cell proliferation, bacterial defence, angiogenesis and collagen synthesis. Even though the role of oxygen in wound healing is not yet completely understood, many experimental and clinical observations have shown wound healing to be impaired under hypoxia. This article provides an overview on the role of oxygen in wound healing and chronic wound pathogenesis, a brief insight into systemic and topical oxygen treatment, and a discussion of the role of wound tissue oximetry. Thus, the aim is to improve the understanding of the role of oxygen in wound healing and to advance our management of wound patients.

Acute oxygen therapy: an audit of prescribing and delivery practices in a tertiary hospital in Perth, Western Australia.

PubMed

Kamran, Anam; Chia, Elisa; Tobin, Claire

2018-02-01

Oxygen is a widely used drug in the hospital setting. However, international audits suggest that oxygen administration practices are often not compliant with prescribed standards. This can place patients at risk and cause serious adverse events. To analyse data related to recent practices of oxygen prescription and administration at Royal Perth Hospital (RPH), Western Australia. The results of this audit aim to guide further research on possible interventional studies implementing key solutions. All patients who received care in the Acute Medical Unit at RPH between 1 September and 14 September 2015 were included in this audit. Patients who were given supplemental oxygen during their admission were selected for further review of records. Appropriate medically indicated target oxygen saturations for each patient were judged under consultation with a respiratory specialist. A total of 65 patients received oxygen supplementation within the study period; 36 of these patients (55.4%) had target oxygen saturations prescribed by doctors, and 25% of the prescribed targets were judged to be inappropriate. In total, 49 patients (75.4%) were exposed to a potential risk from oxygen therapy due to prescription error and/or delivery error. A real risk was identified in 19 patients (29.2%) as they received oxygen at levels outside their appropriate medically indicated target range. The current practices of oxygen prescription and administration within RPH are suboptimal. Patients are placed at risk of oxygen toxicity due to deviation from oxygen prescription guidelines. © 2017 Royal Australasian College of Physicians.

The Role of Oxygen Sensors, Hydroxylases, and HIF in Cardiac Function and Disease.

PubMed

Townley-Tilson, W H Davin; Pi, Xinchun; Xie, Liang

2015-01-01

Ischemic heart disease is the leading cause of death worldwide. Oxygen-sensing proteins are critical components of the physiological response to hypoxia and reperfusion injury, but the role of oxygen and oxygen-mediated effects is complex in that they can be cardioprotective or deleterious to the cardiac tissue. Over 200 oxygen-sensing proteins mediate the effects of oxygen tension and use oxygen as a substrate for posttranslational modification of other proteins. Hydroxylases are an essential component of these oxygen-sensing proteins. While a major role of hydroxylases is regulating the transcription factor HIF, we investigate the increasing scope of hydroxylase substrates. This review discusses the importance of oxygen-mediated effects in the heart as well as how the field of oxygen-sensing proteins is expanding, providing a more complete picture into how these enzymes play a multifaceted role in cardiac function and disease. We also review how oxygen-sensing proteins and hydroxylase function could prove to be invaluable in drug design and therapeutic targets for heart disease.

The Effects of Oxygen Therapy on Myocardial Salvage in ST Elevation Myocardial Infarction Treated with Acute Percutaneous Coronary Intervention: The Supplemental Oxygen in Catheterized Coronary Emergency Reperfusion (SOCCER) Study.

PubMed

Khoshnood, Ardavan; Carlsson, Marcus; Akbarzadeh, Mahin; Bhiladvala, Pallonji; Roijer, Anders; Bodetoft, Stefan; Höglund, Peter; Zughaft, David; Todorova, Lizbet; Erlinge, David; Ekelund, Ulf

2015-01-01

Despite a lack of scientific evidence, oxygen has long been a part of standard treatment for patients with acute myocardial infarction (AMI). However, several studies suggest that oxygen therapy may have negative cardiovascular effects. We here describe a randomized controlled trial, i.e. Supplemental Oxygen in Catheterized Coronary Emergency Reperfusion (SOCCER), aiming to evaluate the effect of oxygen therapy on myocardial salvage and infarct size in patients with ST elevation myocardial infarction (STEMI) treated with a primary percutaneous coronary intervention (PCI). One hundred normoxic STEMI patients accepted for a primary PCI are randomized in the ambulance to either standard oxygen therapy or no supplemental oxygen. All patients undergo cardiovascular magnetic resonance imaging (CMR) 2-6 days after the primary PCI, and a subgroup of 50 patients undergo an extended echocardiography during admission and at 6 months. All patients are followed for 6 months for hospital admission for heart failure and subjective perception of health. The primary endpoint is the myocardial salvage index on CMR. Even though oxygen therapy is a part of standard care, oxygen may not be beneficial for patients with AMI and is possibly even harmful. The results of the present and concurrent oxygen trials may change international treatment guidelines for patients with AMI or ischemia.

The pulmonary vasculature--lessons from Tibetans and from rare diseases of oxygen sensing.

PubMed

Frise, Matthew C; Robbins, Peter A

2015-11-01

What is the topic of this review? This review is principally concerned with results from studies of the pulmonary vasculature in humans, particularly in relation to hypoxia and rare diseases that affect oxygen sensing. What advances does it highlight? This review highlights the degree to which the hypoxia-inducible factor (HIF) transcription system influences human pulmonary vascular responses to hypoxia. Upregulation of the HIF pathway augments hypoxic pulmonary vasoconstriction, while alterations to the pathway found in Tibetans are associated with suppression of the progressive increase in pulmonary artery pressure with sustained hypoxia. It also highlights the potential importance of iron, which modulates the HIF pathway, in modifying the pulmonary vascular response to hypoxia. The human pulmonary circulation loses its natural distensibility during sustained hypoxia, leading to pulmonary arterial hypertension and a much higher workload for the right ventricle. The hypoxia-inducible factor (HIF) pathway is implicated in this pulmonary vascular response to continued hypoxia by animal studies, and additionally, by rare human diseases where the pathway is upregulated. However, there are no known human genetic diseases downregulating HIF. Tibetans, though, demonstrate blunted pulmonary vascular responses to sustained hypoxia. This seems to be accounted for by an altered HIF pathway as a consequence of natural selection over a period of many thousands of years lived at high altitude. In addition to genetic differences, iron is another important modulator of HIF pathway function. Experimental work in humans demonstrates that manipulation of iron stores can influence the behaviour of the pulmonary circulation during hypoxia, in ways analogous to that seen in Tibetans and patients with rare diseases that affect oxygen sensing. The importance of physiological differences in iron bioavailability in modulating hypoxic pulmonary vasoconstriction in health and disease is yet

Non-invasive monitoring of skin inflammation using an oxygen-sensing paint-on bandage

PubMed Central

Li, Zongxi; Navarro-Alvarez, Nalu; Keeley, Emily J.; Nowell, Nicholas H.; Goncalves, Beatriz M. M.; Huang, Christene A.; Evans, Conor L.

2017-01-01

Inflammation involves a cascade of cellular and molecular mediators that ultimately lead to the infiltration of immune cells into the affected area. This inflammatory process in skin is common to many diseases including acne, infection, and psoriasis, with the presence or absence of immune cells a potential diagnostic marker. Here we show that skin inflammation can be non-invasively measured and mapped using a paint-on oxygen sensing bandage in an in vivo porcine inflammation model. After injection of a known inflammatory agent, the bandage could track the increase, plateau, and decrease in oxygen consumption at the injury site over 7 weeks, as well as discern inflammation resultant from injection at various depths beneath the surface of the skin. Both the initial rate of pO2 change and the change in bandage pO2 at equilibration (CBP20) were found to be directly related to the metabolic oxygen consumption rate of the tissue in contact. Healthy skin demonstrated an initial pO2 decrease rate of 6.5 mmHg⋅min−1, and CBP20 of 84 mmHg. Inflamed skin had a significantly higher initial consumption rate of 55 mmHg⋅min−1, and a larger CBP20 of 140 mmHg. The change in the bandage pO2 before and after equilibration with tissue was found to correlate well with histological evidence of skin inflammation in the animals. PMID:29082091

Wound Healing Essentials: Let There Be Oxygen

PubMed Central

Sen, Chandan K.

2009-01-01

The state of wound oxygenation is a key determinant of healing outcomes. From a diagnostic standpoint, measurements of wound oxygenation are commonly used to guide treatment planning such as amputation decision. In preventive applications, optimizing wound perfusion and providing supplemental O2 in the peri-operative period reduces the incidence of post-operative infections. Correction of wound pO2 may, by itself, trigger some healing responses. Importantly, approaches to correct wound pO2 favorably influence outcomes of other therapies such as responsiveness to growth factors and acceptance of grafts. Chronic ischemic wounds are essentially hypoxic. Primarily based on the tumor literature, hypoxia is generally viewed as being angiogenic. This is true with the condition that hypoxia be acute and mild to modest in magnitude. Extreme near-anoxic hypoxia, as commonly noted in problem wounds, is not compatible with tissue repair. Adequate wound tissue oxygenation is required but may not be sufficient to favorably influence healing outcomes. Success in wound care may be improved by a personalized health care approach. The key lies in our ability to specifically identify the key limitations of a given wound and in developing a multifaceted strategy to specifically address those limitations. In considering approaches to oxygenate the wound tissue it is important to recognize that both too little as well as too much may impede the healing process. Oxygen dosing based on the specific need of a wound therefore seems prudent. Therapeutic approaches targeting the oxygen sensing and redox signaling pathways are promising. PMID:19152646

Effects of positive end-expiratory pressure on brain tissue oxygen pressure of severe traumatic brain injury patients with acute respiratory distress syndrome: A pilot study.

PubMed

Nemer, Sérgio Nogueira; Caldeira, Jefferson B; Santos, Ricardo G; Guimarães, Bruno L; Garcia, João Márcio; Prado, Darwin; Silva, Ricardo T; Azeredo, Leandro M; Faria, Eduardo R; Souza, Paulo Cesar P

2015-12-01

To verify whether high positive end-expiratory pressure levels can increase brain tissue oxygen pressure, and also their effects on pulse oxygen saturation, intracranial pressure, and cerebral perfusion pressure. Twenty traumatic brain injury patients with acute respiratory distress syndrome were submitted to positive end-expiratory pressure levels of 5, 10, and 15 cm H2O progressively. The 3 positive end-expiratory pressure levels were used during 20 minutes for each one, whereas brain tissue oxygen pressure, oxygen saturation, intracranial pressure, and cerebral perfusion pressure were recorded. Brain tissue oxygen pressure and oxygen saturation increased significantly with increasing positive end-expiratory pressure from 5 to 10 and from 10 to 15 cm H2O (P=.0001 and P=.0001 respectively). Intracranial pressure and cerebral perfusion pressure did not differ significantly with increasing positive end-expiratory pressure from 5 to 10 and from 10 to 15 cm H2O (P=.16 and P=.79 respectively). High positive end-expiratory pressure levels increased brain tissue oxygen pressure and oxygen saturation, without increase in intracranial pressure or decrease in cerebral perfusion pressure. High positive end-expiratory pressure levels can be used in severe traumatic brain injury patients with acute respiratory distress syndrome as a safe alternative to improve brain oxygenation. Copyright © 2015 Elsevier Inc. All rights reserved.

Singlet oxygen-induced photodegradation of the polymers and dyes in optical sensing materials and the effect of stabilizers on these processes.

PubMed

Enko, Barbara; Borisov, Sergey M; Regensburger, Johannes; Bäumler, Wolfgang; Gescheidt, Georg; Klimant, Ingo

2013-09-12

A comprehensive study of photodegradation processes in optical sensing materials caused by photosensitized singlet oxygen in different polymers is presented. The stabilities of the polymers are accessed in the oxygen consumption measurements performed with help of optical oxygen sensors. Polystyrene and poly(phenylsilesquioxane) are found to be the most stable among the polymers investigated, whereas poly(2,6-dimethyl-p-phenylene oxide) and particularly poly(methyl methacrylate) and their derivatives show the fastest oxygen consumption. The effect of the stabilizers (singlet oxygen quenchers) on the oxygen consumption rates, the photostability of the sensitizer, and the total photon emission (TPE) by singlet oxygen is studied. 1,4-Diazabicyclo[2.2.2]octane (DABCO) was found to significantly reduce both the TPE and the oxygen consumption rates, indicating its role as a physical quencher of singlet oxygen. The addition of DABCO also significantly improved the photostability of the sensitizer. The N-alkylated derivative of DABCO and DABCO covalently grafted to the polystyrene backbone are prepared in an attempt to overcome the volatility and water solubility of the quencher. These derivatives as well as other tertiary amines investigated were found to be inefficient as stabilizing agents, and some of them even negatively affected the oxygen consumption rates.

Effect of olive mill wastewaters on the oxygen consumption by activated sludge microorganisms: an acute toxicity test method.

PubMed

Paixão, S M; Anselmo, A M

2002-01-01

The test for inhibition of oxygen consumption by activated sludge (ISO 8192-1986 (E)) was evaluated as a tool for assessing, the acute toxicity of olive mill wastewaters (OMW). According to the ISO test, information generated by this method may be helpful in estimating the effect of a test material on bacterial communities in the aquatic environment, especially in aerobic biological treatment systems. However, the lack of standardized bioassay methodology for effluents imposed that the test conditions were modified and adapted. The experiments were conducted in the presence or absence of an easily biodegradable carbon source (glucose) with different contact times (20 min and 24 h). The results obtained showed a remarkable stimulatory effect of this effluent to the activated sludge microorganisms. In fact, the oxygen uptake rate values increase with increasing effluent concentrations and contact times up to 0.98 microl O(2) h(-1) mg(-1) dry weight for a 100% OMW sample, 24 h contact time, with blanks exhibiting an oxygen uptake rate of ca. 1/10 of this value (0.07-0.10). It seems that the application of the ISO test as an acute toxicity test for effluents should be reconsidered, with convenient adaptation for its utilization as a method of estimating the effect on bacterial communities present in aerobic biological treatment systems. Copyright 2002 John Wiley & Sons, Ltd.

Circulatory limits to oxygen supply during an acute temperature increase in the Chinook salmon (Oncorhynchus tshawytscha).

PubMed

Clark, Timothy D; Sandblom, Erik; Cox, Georgina K; Hinch, Scott G; Farrell, Anthony P

2008-11-01

This study was undertaken to provide a comprehensive set of data relevant to disclosing the physiological effects and possible oxygen transport limitations in the Chinook salmon (Oncorhynchus tshawytscha) during an acute temperature change. Fish were instrumented with a blood flow probe around the ventral aorta and catheters in the dorsal aorta and sinus venosus. Water temperature was progressively increased from 13 degrees C in steps of 4 degrees C up to 25 degrees C. Cardiac output increased from 29 to 56 ml.min(-1).kg(-1) between 13 and 25 degrees C through an increase in heart rate (58 to 105 beats/min). Systemic vascular resistance was reduced, causing a stable dorsal aortic blood pressure, yet central venous blood pressure increased significantly at 25 degrees C. Oxygen consumption rate increased from 3.4 to 8.7 mg.min(-1).kg(-1) during the temperature increase, although there were signs of anaerobic respiration at 25 degrees C in the form of increased blood lactate and decreased pH. Arterial oxygen partial pressure was maintained during the heat stress, although venous oxygen partial pressure (Pv(O(2))) and venous oxygen content were significantly reduced. Cardiac arrhythmias were prominent in three of the largest fish (>4 kg) at 25 degrees C. Given the switch to anaerobic metabolism and the observation of cardiac arrhythmias at 25 degrees C, we propose that the cascade of venous oxygen depletion results in a threshold value for Pv(O(2)) of around 1 kPa. At this point, the oxygen supply to systemic and cardiac tissues is compromised, such that the oxygen-deprived and acidotic myocardium becomes arrhythmic, and blood perfusion through the gills and to the tissues becomes compromised.

DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE

DOEpatents

Bradner, H.; Gordon, H.S.

1957-12-24

A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

A pilot study: a combined therapy using polymyxin-B hemoperfusion and extracorporeal membrane oxygenation for acute exacerbation of interstitial pneumonia.

PubMed

Itai, Junji; Ohshimo, Shinichiro; Kida, Yoshiko; Ota, Kohei; Iwasaki, Yasumasa; Hirohashi, Nobuyuki; Bonella, Francesco; Guzman, Josune; Costabel, Ulrich; Kohno, Nobuoki; Tanigawa, Koichi

2015-01-05

Direct hemoperfusion with polymyxin B-immobilized fiber (PMX-DHP) might be beneficial for treating acute exacerbation (AE) of interstitial pneumonia (IP). Venovenous extracorporeal membranous oxygenation (VV-ECMO) is an emerging tool to avoid ventilator-induced lung injury. This is a report presenting the first three patients with AE of IP treated with a combined therapy of PMX-DHP and VV-ECMO. Patient 1 was a 68-year-old male with acute interstitial pneumonia, patient 2 a 67-year-old male with AE of idiopathic pulmonary fibrosis, and patient 3 a 61-year-old female with AE of collagen vascular disease-associated interstitial pneumonia. All patients were severely hypoxemic and required mechanical ventilation. A combined therapy using PMX-DHP and VV-ECMO was initiated with support of intravenous corticosteroids and antibiotics. Radiological findings, oxygenation and laboratory findings markedly improved and all patients survived without severe complications. A combined therapy of PMX-DHP and VV-ECMO might be a therapeutic option for AE of IP.

Surface acoustic wave devices for harsh environment wireless sensing

DOE PAGES

Greve, David W.; Chin, Tao -Lun; Zheng, Peng; ...

2013-05-24

In this study, langasite surface acoustic wave devices can be used to implement harsh environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensormore » with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity.« less

Multi-modal in vivo imaging of brain blood oxygenation, blood flow and neural calcium dynamics during acute seizures

NASA Astrophysics Data System (ADS)

Ringuette, Dene; Jeffrey, Melanie A.; Carlen, Peter L.; Levi, Ofer

2016-03-01

Dysfunction of the vascular endothelium has been implicated in the development of epilepsy. To better understand the relation between vascular function and seizure and provide a foundation for interpreting results from functional imaging in chronic disease models, we investigate the relationship between intracellular calcium dynamics and local cerebral blood flow and blood oxygen saturation during acute seizure-like events and pharmacological seizure rescue. To probe the relation between the aforementioned physiological markers in an acute model of epilepsy in rats, we integrated three different optical modalities together with electrophysiological recordings: Laser speckle contrast imaging (LSCI) was used to study changes in flow speeds, Intrinsic optical signal imaging (IOSI) was used to monitor changes in oxygenated, de-oxygenated, and total hemoglobin concentration, and Calcium-sensitive dye imaging was used to monitor intracellular calcium dynamics. We designed a dedicated cortical flow chamber to remove superficial blood and dye resulting from the injection procedure, which reduced spurious artifacts. The near infrared light used for IOSI and LSCI was delivered via a light pipe integrated with the flow chamber to minimize the effect of fluid surface movement on illumination stability. Calcium-sensitive dye was injected via a glass electrode used for recording the local field potential. Our system allowed us to observe and correlate increases in intracellular calcium, blood flow and blood volume during seizure-like events and provide a quantitative analysis of neurovascular coupling changes associated with seizure rescue via injection of an anti-convulsive agent.

Proteomic analysis reveals diverse proline hydroxylation-mediated oxygen-sensing cellular pathways in cancer cells

PubMed Central

Liu, Bing; Gao, Yankun; Ruan, Hai-Bin; Chen, Yue

2016-01-01

Proline hydroxylation is a critical cellular mechanism regulating oxygen-response pathways in tumor initiation and progression. Yet, its substrate diversity and functions remain largely unknown. Here, we report a system-wide analysis to characterize proline hydroxylation substrates in cancer cells using an immunoaffinity-purification assisted proteomics strategy. We identified 562 sites from 272 proteins in HeLa cells. Bioinformatic analysis revealed that proline hydroxylation substrates are significantly enriched with mRNA processing and stress-response cellular pathways with canonical and diverse flanking sequence motifs. Structural analysis indicates a significant enrichment of proline hydroxylation participating in the secondary structure of substrate proteins. Our study identified and validated Brd4, a key transcription factor, as a novel proline hydroxylation substrate. Functional analysis showed that the inhibition of proline hydroxylation pathway significantly reduced the proline hydroxylation abundance on Brd4 and affected Brd4-mediated transcriptional activity as well as cell proliferation in AML leukemia cells. Taken together, our study identified a broad regulatory role of proline hydroxylation in cellular oxygen-sensing pathways and revealed potentially new targets that dynamically respond to hypoxia microenvironment in tumor cells. PMID:27764789

In vitro oxygen sensing using intraocular microrobots.

PubMed

Ergeneman, Olgaç; Chatzipirpiridis, George; Pokki, Juho; Marín-Suárez, Marta; Sotiriou, Georgios A; Medina-Rodríguez, Santiago; Sánchez, Jorge F Fernández; Fernández-Gutiérrez, Alberto; Pané, Salvador; Nelson, Bradley J

2012-11-01

We present a luminescence oxygen sensor integrated with a wireless intraocular microrobot for minimally-invasive diagnosis. This microrobot can be accurately controlled in the intraocular cavity by applying magnetic fields. The microrobot consists of a magnetic body susceptible to magnetic fields and a sensor coating. This coating embodies Pt(II) octaethylporphine (PtOEP) dyes as the luminescence material and polystyrene as a supporting matrix, and it can be wirelessly excited and read out by optical means. The sensor works based on quenching of luminescence in the presence of oxygen. The excitation and emission spectrum, response time, and oxygen sensitivity of the sensor were characterized using a spectrometer. A custom device was designed and built to use this sensor for intraocular measurements with the microrobot. Due to the intrinsic nature of luminescence lifetimes, a frequency-domain lifetime measurement approach was used. An alternative sensor design with increased performance was demonstrated by using poly(styrene-co-maleic anhydride) (PS-MA) and PtOEP nanospheres.

Veno-arterial extracorporeal membrane oxygenation for adult cardiovascular failure.

PubMed

Pellegrino, Vincent; Hockings, Lisen E; Davies, Andrew

2014-10-01

To examine the utility and technical challenges of applying veno-arterial extracorporeal membrane oxygenation for acute cardiovascular failure in adults with acute and chronic causes of heart failure. The role of mechanical circulatory support in acute cardiovascular continues to evolve as technology and clinical experience develop. There is increasing interest in the role of veno-arterial extracorporeal membrane oxygenation as a bridging therapy and as an adjunct to conventional cardiopulmonary resuscitation. Veno-arterial extracorporeal membrane oxygenation is an expensive, complex, resource intensive support. It is essential that its future use be guided by evidence obtained from centres that have demonstrated timely, safe support.

Effects of different acute hypoxic regimens on tissue oxygen profiles and metabolic outcomes.

PubMed

Reinke, Christian; Bevans-Fonti, Shannon; Drager, Luciano F; Shin, Mi-Kyung; Polotsky, Vsevolod Y

2011-09-01

Obstructive sleep apnea (OSA) causes intermittent hypoxia (IH) during sleep. Both obesity and OSA are associated with insulin resistance and systemic inflammation, which may be attributable to tissue hypoxia. We hypothesized that a pattern of hypoxic exposure determines both oxygen profiles in peripheral tissues and systemic metabolic outcomes, and that obesity has a modifying effect. Lean and obese C57BL6 mice were exposed to 12 h of intermittent hypoxia 60 times/h (IH60) [inspired O₂ fraction (Fi(O₂)) 21-5%, 60/h], IH 12 times/h (Fi(O₂) 5% for 15 s, 12/h), sustained hypoxia (SH; Fi(O₂) 10%), or normoxia while fasting. Tissue oxygen partial pressure (Pti(O₂)) in liver, skeletal muscle and epididymal fat, plasma leptin, adiponectin, insulin, blood glucose, and adipose tumor necrosis factor-α (TNF-α) were measured. In lean mice, IH60 caused oxygen swings in the liver, whereas fluctuations of Pti(O₂) were attenuated in muscle and abolished in fat. In obese mice, baseline liver Pti(O₂) was lower than in lean mice, whereas muscle and fat Pti(O₂) did not differ. During IH, Pti(O₂) was similar in obese and lean mice. All hypoxic regimens caused insulin resistance. In lean mice, hypoxia significantly increased leptin, especially during SH (44-fold); IH60, but not SH, induced a 2.5- to 3-fold increase in TNF-α secretion by fat. Obesity was associated with striking increases in leptin and TNF-α, which overwhelmed effects of hypoxia. In conclusion, IH60 led to oxygen fluctuations in liver and muscle and steady hypoxia in fat. IH and SH induced insulin resistance, but inflammation was increased only by IH60 in lean mice. Obesity caused severe inflammation, which was not augmented by acute hypoxic regimens.

Effects of different acute hypoxic regimens on tissue oxygen profiles and metabolic outcomes

PubMed Central

Bevans-Fonti, Shannon; Drager, Luciano F.; Shin, Mi-Kyung; Polotsky, Vsevolod Y.

2011-01-01

Obstructive sleep apnea (OSA) causes intermittent hypoxia (IH) during sleep. Both obesity and OSA are associated with insulin resistance and systemic inflammation, which may be attributable to tissue hypoxia. We hypothesized that a pattern of hypoxic exposure determines both oxygen profiles in peripheral tissues and systemic metabolic outcomes, and that obesity has a modifying effect. Lean and obese C57BL6 mice were exposed to 12 h of intermittent hypoxia 60 times/h (IH60) [inspired O2 fraction (FiO2) 21–5%, 60/h], IH 12 times/h (FiO2 5% for 15 s, 12/h), sustained hypoxia (SH; FiO2 10%), or normoxia while fasting. Tissue oxygen partial pressure (PtiO2) in liver, skeletal muscle and epididymal fat, plasma leptin, adiponectin, insulin, blood glucose, and adipose tumor necrosis factor-α (TNF-α) were measured. In lean mice, IH60 caused oxygen swings in the liver, whereas fluctuations of PtiO2 were attenuated in muscle and abolished in fat. In obese mice, baseline liver PtiO2 was lower than in lean mice, whereas muscle and fat PtiO2 did not differ. During IH, PtiO2 was similar in obese and lean mice. All hypoxic regimens caused insulin resistance. In lean mice, hypoxia significantly increased leptin, especially during SH (44-fold); IH60, but not SH, induced a 2.5- to 3-fold increase in TNF-α secretion by fat. Obesity was associated with striking increases in leptin and TNF-α, which overwhelmed effects of hypoxia. In conclusion, IH60 led to oxygen fluctuations in liver and muscle and steady hypoxia in fat. IH and SH induced insulin resistance, but inflammation was increased only by IH60 in lean mice. Obesity caused severe inflammation, which was not augmented by acute hypoxic regimens. PMID:21737828

Steam inhalation or humidified oxygen for acute bronchiolitis in children up to three years of age.

PubMed

Umoren, Rachel; Odey, Friday; Meremikwu, Martin M

2011-01-19

Acute bronchiolitis is a common respiratory infection and a major cause of morbidity in young children. It is treated with bronchodilators (for example, salbutamol), corticosteroids or humidified air (steam inhalation or cool mist). Steam inhalation is preferred in low-income countries as it is inexpensive and easily available. It is thought to act as a secretolytic agent to lighten secretions in the respiratory tract and relieve respiratory distress. To evaluate the effect of steam inhalation or humidified oxygen to relieve respiratory distress and to evaluate adverse events in children up to three years old with acute bronchiolitis. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 1) which contains the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1950 to February Week 4, 2010), EMBASE.com (1974 to March 2010), CINAHL (1981 to March 2010), AMED (1985 to March 2010), Web of Science (2000 to March 2010) and LILACS (1982 to March 2010). Randomised controlled trials involving children up to three years old with bronchiolitis comparing steam inhalation (or cool mist) or humidified oxygen against bronchodilators, corticosteroids or placebo; alone or in combination. Two review authors independently assessed trial quality and extracted data. Only one study (156 children aged between seven weeks and 24 months with signs and symptoms of bronchiolitis) met the eligibility criteria for inclusion. Participants were randomised into three groups: nebulised salbutamol, nebulised saline and mist in a tent. The results showed a significant decrease in respiratory distress symptom (RDS) score in the nebulised salbutamol group but no significant decrease in the RDS score in the mist in a tent or nebulised saline groups. The study did not report on adverse effects of the interventions. Steam inhalation (or cool mist therapy) is commonly used to treat acute bronchiolitis in resource-constrained settings

Using Yttra-Stabilized Zirconium Oxide Ceramics to Sense pH and Oxygen in Hydrothermal and Geothermal Applications

NASA Astrophysics Data System (ADS)

Manna, M. F.; Grandstaff, D. E.; Ulmer, G. C.

2002-05-01

Zirconium-Oxide ceramics stabilized with ~8-wt% Yttrium-Oxide can be employed to sense pH in high temperature (>90oC) aqueous environments with an accuracy of 0.05 pH log units (Lvov et al., in press), and to sense the fugacity of oxygen (fO2) in low temperature (>230oC) gaseous environments with an accuracy of 0.2 (fO2) log units. The major components, in two commercially available yttria-stabilized ceramics are yttria ( ~8-wt%) and zirconia ( ~91-wt%) with minor amounts of Ti, Fe and U. The textural differences in the two ceramics produces significantly different emf vs. 10,000/T responses. Response error can be introduced by: the ionic contribution of the softening glass, the catalytic action of the Pt sensor components, and the presence of Ti and Fe in the ceramic, which has been shown to alter the oxygen diffusivity of the ceramic. (Merino et al., 1996) The first type of ceramic contains a 3-dimensionally-continuous Ca-Al-Si feldspathic glass that acts as a sintering aid during manufacturing. The glass, which has a higher ionic conductivity than the zirconia ceramic, reduces the bulk resistivity and induces an error over the temperature ranges representing the softening point of the glass. The glass also reduces durability of the ceramic. When the glass hydrates it produces zeolites, which grow primarily in the triple-grain-junctions of the ceramic. Thus mechanically weakening the ceramic generating electronic, ionic and mechanical stability problems. The second type of ceramic contains no grain boundary glass, but does contain discrete silicate phases (such as diopside, wollastonite, periclase, silica, etc.) in the triple-grain-junctions. Because there is no inter-granular glass, the type two ceramic does have a greater bulk resistivity compared with the type one ceramic. In a gas-sensing configuration, resistivity has been shown to affect the minimum temperature of sensor operation. A sensor with a higher bulk resistivity must reach a higher minimum

Luminescence materials for pH and oxygen sensing in microbial cells - structures, optical properties, and biological applications.

PubMed

Zou, Xianshao; Pan, Tingting; Chen, Lei; Tian, Yanqing; Zhang, Weiwen

2017-09-01

Luminescence including fluorescence and phosphorescence sensors have been demonstrated to be important for studying cell metabolism, and diagnosing diseases and cancer. Various design principles have been employed for the development of sensors in different formats, such as organic molecules, polymers, polymeric hydrogels, and nanoparticles. The integration of the sensing with fluorescence imaging provides valuable tools for biomedical research and applications at not only bulk-cell level but also at single-cell level. In this article, we critically reviewed recent progresses on pH, oxygen, and dual pH and oxygen sensors specifically for their application in microbial cells. In addition, we focused not only on sensor materials with different chemical structures, but also on design and applications of sensors for better understanding cellular metabolism of microbial cells. Finally, we also provided an outlook for future materials design and key challenges in reaching broad applications in microbial cells.

Lung recruitment manoeuvres are effective in regaining lung volume and oxygenation after open endotracheal suctioning in acute respiratory distress syndrome

PubMed Central

Dyhr, Thomas; Bonde, Jan; Larsson, Anders

2003-01-01

Introduction Lung collapse is a contributory factor in the hypoxaemia that is observed after open endotracheal suctioning (ETS) in patients with acute lung injury and acute respiratory distress syndrome. Lung recruitment (LR) manoeuvres may be effective in rapidly regaining lung volume and improving oxygenation after ETS. Materials and method A prospective, randomized, controlled study was conducted in a 15-bed general intensive care unit at a university hospital. Eight consecutive mechanically ventilated patients with acute lung injury or acute respiratory distress syndrome were included. One of two suctioning procedures was performed in each patient. In the first procedure, ETS was performed followed by LR manoeuvre and reconnection to the ventilator with positive end-expiratory pressure set at 1 cmH2O above the lower inflexion point, and after 60 min another ETS (but without LR manoeuvre) was performed followed by reconnection to the ventilator with similar positive end-expiratory pressure; the second procedure was the same as the first but conducted in reverse order. Before (baseline) and over 25 min following each ETS procedure, partial arterial oxygen tension (PaO2) and end-expiratory lung volume were measured. Results After ETS, PaO2 decreased by 4.3(0.9–9.7)kPa (median and range; P < 0.005). After LR manoeuvre, PaO2 recovered to baseline. Without LR manoeuvre, PaO2 was reduced (P = 0.05) until 7 min after ETS. With LR manoeuvre end-expiratory lung volume was unchanged after ETS, whereas without LR manoeuvre end-expiratory lung volume was still reduced (approximately 10%) at 5 and 15 min after ETS (P = 0.01). Discussion A LR manoeuvre immediately following ETS was, as an adjunct to positive end-expiratory pressure, effective in rapidly counteracting the deterioration in PaO2 and lung volume caused by open ETS in ventilator-treated patients with acute lung injury or acute respiratory distress syndrome. PMID:12617741

30 CFR 57.8527 - Oxygen-deficiency testing.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Oxygen-deficiency testing. 57.8527 Section 57... Underground Only § 57.8527 Oxygen-deficiency testing. Flame safety lamps or other suitable devices shall be used to test for acute oxygen deficiency. ...

30 CFR 57.8527 - Oxygen-deficiency testing.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Oxygen-deficiency testing. 57.8527 Section 57... Underground Only § 57.8527 Oxygen-deficiency testing. Flame safety lamps or other suitable devices shall be used to test for acute oxygen deficiency. ...

30 CFR 57.8527 - Oxygen-deficiency testing.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Oxygen-deficiency testing. 57.8527 Section 57... Underground Only § 57.8527 Oxygen-deficiency testing. Flame safety lamps or other suitable devices shall be used to test for acute oxygen deficiency. ...

30 CFR 57.8527 - Oxygen-deficiency testing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Oxygen-deficiency testing. 57.8527 Section 57... Underground Only § 57.8527 Oxygen-deficiency testing. Flame safety lamps or other suitable devices shall be used to test for acute oxygen deficiency. ...

30 CFR 57.8527 - Oxygen-deficiency testing.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Oxygen-deficiency testing. 57.8527 Section 57... Underground Only § 57.8527 Oxygen-deficiency testing. Flame safety lamps or other suitable devices shall be used to test for acute oxygen deficiency. ...

Effects of a human recombinant alkaline phosphatase on renal hemodynamics, oxygenation and inflammation in two models of acute kidney injury

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, Esther, E-mail: esther.peters@radboudumc.n

Two small clinical trials indicated that administration of bovine intestinal alkaline phosphatase (AP) improves renal function in critically ill patients with sepsis-associated acute kidney injury (AKI), for which the mechanism of action is not completely understood. Here, we investigated the effects of a newly developed human recombinant AP (recAP) on renal oxygenation and hemodynamics and prevention of kidney damage and inflammation in two in vivo AKI models. To induce AKI, male Wistar rats (n = 18) were subjected to renal ischemia (30 min) and reperfusion (I/R), or sham-operated. In a second model, rats (n = 18) received a 30 minmore » infusion of lipopolysaccharide (LPS; 2.5 mg/kg), or saline, and fluid resuscitation. In both models, recAP (1000 U/kg) was administered intravenously (15 min before reperfusion, or 90 min after LPS). Following recAP treatment, I/R-induced changes in renal blood flow, renal vascular resistance and oxygen delivery at early, and cortical microvascular oxygen tension at late reperfusion were no longer significantly affected. RecAP did not influence I/R-induced effects on mean arterial pressure. During endotoxemia, recAP treatment did not modulate the LPS-induced changes in systemic hemodynamics and renal oxygenation. In both models, recAP did exert a clear renal protective anti-inflammatory effect, demonstrated by attenuated immunostaining of inflammatory, tubular injury and pro-apoptosis markers. Whether this renal protective effect is sufficient to improve outcome of patients suffering from sepsis-associated AKI is being investigated in a large clinical trial. - Highlights: • Human recombinant alkaline phosphatase (recAP) is a potential new therapy for sepsis-associated acute kidney injury (AKI). • RecAP can modulate renal oxygenation and hemodynamics immediately following I/R-induced AKI. • RecAP did not modulate endotoxemia-induced changes in systemic hemodynamics and renal oxygenation. • RecAP did exert a clear renal

Oxygen partial pressure sensor

DOEpatents

Dees, D.W.

1994-09-06

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

Oxygen partial pressure sensor

DOEpatents

Dees, Dennis W.

1994-01-01

A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

Optical Oxygen Micro- and Nanosensors for Plant Applications

PubMed Central

Ast, Cindy; Schmälzlin, Elmar; Löhmannsröben, Hans-Gerd; van Dongen, Joost T.

2012-01-01

Pioneered by Clark's microelectrode more than half a century ago, there has been substantial interest in developing new, miniaturized optical methods to detect molecular oxygen inside cells. While extensively used for animal tissue measurements, applications of intracellular optical oxygen biosensors are still scarce in plant science. A critical aspect is the strong autofluorescence of the green plant tissue that interferes with optical signals of commonly used oxygen probes. A recently developed dual-frequency phase modulation technique can overcome this limitation, offering new perspectives for plant research. This review gives an overview on the latest optical sensing techniques and methods based on phosphorescence quenching in diverse tissues and discusses the potential pitfalls for applications in plants. The most promising oxygen sensitive probes are reviewed plus different oxygen sensing structures ranging from micro-optodes to soluble nanoparticles. Moreover, the applicability of using heterologously expressed oxygen binding proteins and fluorescent proteins to determine changes in the cellular oxygen concentration are discussed as potential non-invasive cellular oxygen reporters. PMID:22969334

Changes in Oxygen Consumption and Heart Rate After Acute Myocardial Infarction During 6-Month Follow-up.

PubMed

Choe, Yuri; Han, Jae-Young; Choi, In-Sung; Park, Hyeng-Kyu

2018-06-01

Exercise intensity is a particularly important determinant of physiological responses to exercise training in patients with acute myocardial infarction. Heart rate (HR) is commonly used as a practical way of prescribing and monitoring exercise as specific intensities based on a linear relationship between the percentage of maximum HR (%HR max ) and the percentage of maximum oxygen consumption (%VO 2max ) regardless of age, gender, or exercise mode. To examine the change in variability in the correlation between %HR max and %VO 2max after acute myocardial infarction. Retrospective study. Regional cardio-cerebrovascular center at a tertiary hospital. A total of 66 patients were enrolled who were referred for cardiac rehabilitation (CR) after percutaneous intervention, and who had reached stage 3 of the modified Bruce Protocol (mBP) on an exercise tolerance test (ETT). There were 54 men and 12 women with an average age of 56.7 ± 9.48 years, ejection fraction (EF) of 56.4% ± 8.89%, and body mass index (BMI) of 24.73 ± 2.86 kg/m 2 . All patients participated in a 4-week outpatient CR program and underwent ETT with a gas analyzer to determine maximal heart rate and maximal oxygen consumption before CR and 1 month, 3 months, and 6 months after CR. VO 2max and HR max were defined as the highest values attained during the ETT. The HR and VO 2 values at each stage of the mBP were expressed as percentages of their maximum. %HR max and %VO 2max were calculated at each stage of the mBP. The maximum METs and VO 2max significantly improved at 1 month after CR, but not significantly at 3 and 6 months after CR. The correlation between VO 2max and HR max progressively changed in a favorable manner during CR. The relationship between %HR max and %VO 2max indicated a coefficient of variation before and 1, 3, and 6 months after of 0.800, 0.826, 0.832, and 0.880, respectively. This study showed that the %HR max correlates better with the %VO 2max in the late-stage post-AMI than in

Electrochemical Sensing for a Rapidly Evolving World

NASA Astrophysics Data System (ADS)

Mullen, Max Robertson

This dissertation focuses on three projects involving the development of harsh environment gas sensors. The first project discusses the development of a multipurpose oxygen sensor electrode for use in sealing with the common electrolyte yttria stabilized zirconia. The purpose of the sealing function is to produce an internal reference environment maintained by a metal/metal oxide mixture, a criteria for miniaturization of potentiometric oxygen sensing technology. This sensor measures a potential between the internal reference and a sensing environment. The second project discusses the miniaturization of an oxygen sensor and the fabrication of a more generalized electrochemical sensing platform. The third project discusses the discovery of a new mechanism in the electrochemical sensing of ammonia through molecular recognition and the utilization of a sensor taking advantage of the new mechanism. An initial study involving the development of a microwave synthesized La0.8Sr0.2Al0.9Mn0.1O3 sensor electrode material illustrates the ability of the material developed to meet ionic and electronic conducting requirements for effective and Nernstian oxygen sensing. In addition the material deforms plastically under hot isostatic pressing conditions in a similar temperature and pressure regime with yttria stabilized zirconia to produce a seal and survive temperatures up to 1350 °C. In the second project we show novel methods to seal an oxygen environment inside a device cavity to produce an electrochemical sensor body using room temperature plasma-activated bonding and low temperature and pressure assisted plasma-activated bonding with silicon bodies, both in a clean room environment. The evolution from isostatic hot pressing methods towards room temperature complementary metal oxide semiconductor (CMOS) compatible technologies using single crystal silicon substrates in the clean room allows the sealing of devices on a much larger scale. Through this evolution in bonding

Oxygen and life on earth: an anesthesiologist's views on oxygen evolution, discovery, sensing, and utilization.

PubMed

Lindahl, Sten G E

2008-07-01

The advent of oxygenic photosynthesis and the accumulation of oxygen in our atmosphere opened up new possibilities for the development of life on Earth. The availability of oxygen, the most capable electron acceptor on our planet, allowed the development of highly efficient energy production from oxidative phosphorylation, which shaped the evolutionary development of aerobic life forms from the first multicellular organisms to the vertebrates.

Improved oxygenation 24 hours after transition to airway pressure release ventilation or high-frequency oscillatory ventilation accurately discriminates survival in immunocompromised pediatric patients with acute respiratory distress syndrome*.

PubMed

Yehya, Nadir; Topjian, Alexis A; Thomas, Neal J; Friess, Stuart H

2014-05-01

Children with an immunocompromised condition and requiring invasive mechanical ventilation have high risk of death. Such patients are commonly transitioned to rescue modes of nonconventional ventilation, including airway pressure release ventilation and high-frequency oscillatory ventilation, for acute respiratory distress syndrome refractory to conventional ventilation. Our aim was to describe our experience with airway pressure release ventilation and high-frequency oscillatory ventilation in children with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation and to identify factors associated with survival. Retrospective cohort study. Tertiary care, university-affiliated PICU. Sixty pediatric patients with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation. None. Demographic data, ventilator settings, arterial blood gases, oxygenation index, and PaO(2)/FIO(2) were recorded before transition to either mode of nonconventional ventilation and at predetermined intervals after transition for up to 5 days. Mortality in the entire cohort was 63% and did not differ between patients transitioned to airway pressure release ventilation and high-frequency oscillatory ventilation. For both airway pressure release ventilation and high-frequency oscillatory ventilation, improvements in oxygenation index and PaO(2)/FIO(2) at 24 hours expressed as a fraction of pretransition values (oxygenation index(24)/oxygenation index(pre) and PaO(2)/FIO(224)/PaO(2)/FIO(2pre)) reliably discriminated nonsurvivors from survivors, with receiver operating characteristic areas under the curves between 0.89 and 0.95 (p for all curves < 0.001). Sensitivity-specificity analysis suggested that less than 15% reduction in oxygenation index (90% sensitive, 75% specific) or less than 90

Correlated oxygen-sensing PLIM, cell metabolism FLIM and applications

NASA Astrophysics Data System (ADS)

Rück, A. C.; Kalinina, S.; Schäfer, P.; von Einem, B.; von Arnim, C.

2017-02-01

Correlated imaging of phosphorescence and fluorescence lifetime parameters of metabolic markers is a challenge for direct investigating mechanisms related to cell metabolism and oxygen tension. A large variety of clinical phenotypes is associated with mitochondrial defects accomplished with changes in cell metabolism. In many cases the hypoxic microenvironment of cancer cells shifts metabolism from oxidative phosphorylation (OXPHOS) to anaerobic or aerobic glycolysis, a process known as "Warburg" effect. Also during stem cell differentiation a switch in cell metabolism is observed. Mitochondrial dysfunction associated with hypoxia has been invoked in many complex disorders such as type 2 diabetes, Alzheimeŕs disease, cardiac ischemia/reperfusion injury, tissue inflammation and cancer. Cellular responses to oxygen tension have been studied extensively, optical imaging techniques based on time correlated single photon counting (TCSPC) to detect oxygen concentration and distribution are therefore of prominent interest. Moreover, they offer the possibility by inspecting fluorescence decay characteristics of intrinsic coenzymes to directly image metabolic pathways, whereas oxygen tension can be determined by considering the phosphorescence lifetime of a phosphorescent probe. The combination of both fluorescence lifetime imaging (FLIM) of coenzymes like NAD(P)H and FAD and phosphorescence lifetime (PLIM) of phosphorescent dyes could provide valuable information about correlation of metabolic pathways and oxygen tension.

Acute administration of high doses of taurine does not substantially improve high-intensity running performance and the effect on maximal accumulated oxygen deficit is unclear.

PubMed

Milioni, Fabio; Malta, Elvis de Souza; Rocha, Leandro George Spinola do Amaral; Mesquita, Camila Angélica Asahi; de Freitas, Ellen Cristini; Zagatto, Alessandro Moura

2016-05-01

The aim of the present study was to investigate the effects of acute administration of taurine overload on time to exhaustion (TTE) of high-intensity running performance and alternative maximal accumulated oxygen deficit (MAODALT). The study design was a randomized, placebo-controlled, crossover design. Seventeen healthy male volunteers (age: 25 ± 6 years; maximal oxygen uptake: 50.5 ± 7.6 mL·kg(-1)·min(-1)) performed an incremental treadmill-running test until voluntary exhaustion to determine maximal oxygen uptake and exercise intensity at maximal oxygen uptake. Subsequently, participants completed randomly 2 bouts of supramaximal treadmill-running at 110% exercise intensity at maximal oxygen uptake until exhaustion (placebo (6 g dextrose) or taurine (6 g) supplementation), separated by 1 week. MAODALT was determined using a single supramaximal effort by summating the contribution of the phosphagen and glycolytic pathways. When comparing the results of the supramaximal trials (i.e., placebo and taurine conditions) no differences were observed for high-intensity running TTE (237.70 ± 66.00 and 277.30 ± 40.64 s; p = 0.44) and MAODALT (55.77 ± 8.22 and 55.06 ± 7.89 mL·kg(-1); p = 0.61), which seem to indicate trivial and unclear differences using the magnitude-based inferences approach, respectively. In conclusion, acute 6 g taurine supplementation before exercise did not substantially improve high-intensity running performance and showed an unclear effect on MAODALT.

Novel nanostructured oxygen sensor

NASA Astrophysics Data System (ADS)

Boardman, Alan James

New government regulations and industry requirements for medical oxygen sensors require the development of alternate materials and process optimization of primary sensor components. Current oxygen sensors are not compliant with the Restriction of Hazardous Substances (RoHS) Directive. This work focused on two areas. First, was finding suitable readily available materials for the sensor anodes. Second was optimizing the processing of the sensor cathode membrane for reduced delamination. Oxygen sensors were made using tin (Sn) and bismuth (Bi) electrodes, potassium hydroxide (KOH) and acetic acid (CH3COOH) electrolytes with platinum (Pt) and gold (Au) reference electrodes. Bi electrodes were fabricated by casting and pressing processes. Electrochemical characterization of the Sn and Bi electrodes was performed by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and sensing characterization per BSEN ISO 21647:2009 at various oxygen percentages, 0%, 20.9% and 100% oxygen levels with an automated test apparatus. The Sn anode with both electrolyte solutions showed good oxygen sensing properties and performance in a sensor. This system shows promise for replacement of Pb electrodes as required by the RoHS Directive. The Bi anode with Au cathode in both KOH and CH3COOH electrolytes showed acceptable performance and oxygen sensing properties. The Bi anodes fabricated by separate manufacturing methods demonstrated effectiveness for use in medical oxygen sensors. Gold thin films were prepared by magnetron sputtering on Flouroethylene Polymer (FEP) films. The FEP substrate temperature ranged from -77°C to 50°C. X-Ray Diffraction (XRD) and 4-point resistivity characterized the effects of substrate temperature to Au thin film particle size. XRD peak broadening and resistivity measurements showed a strong correlation of particle size to FEP substrate temperature. Particle size at 50°C was 594A and the -77°C particle size was 2.4 x 103A. Substrate

Smart oxygen cuvette for optical monitoring of dissolved oxygen in biological blood samples

NASA Astrophysics Data System (ADS)

Dabhi, Harish; Alla, Suresh Kumar; Shahriari, Mahmoud R.

2010-02-01

A smart Oxygen Cuvette is developed by coating the inner surface of a cuvette with oxygen sensitive thin film material. The coating is glass like sol-gel based sensor that has an embedded ruthenium compound in the glass film. The fluorescence of the ruthenium is quenched depending on the oxygen level. Ocean Optics phase fluorometer, NeoFox is used to measure this rate of fluorescence quenching and computes it for the amount of oxygen present. Multimode optical fibers are used for transportation of light from an LED source to cuvette and from cuvette to phase fluorometer. This new oxygen sensing system yields an inexpensive solution for monitoring the dissolved oxygen in samples for biological and medical applications. In addition to desktop fluorometers, smart oxygen cuvettes can be used with the Ocean Optics handheld Fluorometers, NeoFox Sport. The Smart Oxygen Cuvettes provide a resolution of 4PPB units, an accuracy of less than 5% of the reading, and 90% response in less than 10 seconds.

Surface acoustic wave oxygen sensor

NASA Technical Reports Server (NTRS)

Collman, James P.; Oglesby, Donald M.; Upchurch, Billy T.; Leighty, Bradley D.; Zhang, Xumu; Herrmann, Paul C.

1994-01-01

A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.

Adenosine A2a receptors and O2 sensing in development

PubMed Central

2011-01-01

Reduced mitochondrial oxidative phosphorylation, via activation of adenylate kinase and the resulting exponential rise in the cellular AMP/ATP ratio, appears to be a critical factor underlying O2 sensing in many chemoreceptive tissues in mammals. The elevated AMP/ATP ratio, in turn, activates key enzymes that are involved in physiologic adjustments that tend to balance ATP supply and demand. An example is the conversion of AMP to adenosine via 5′-nucleotidase and the resulting activation of adenosine A2A receptors, which are involved in acute oxygen sensing by both carotid bodies and the brain. In fetal sheep, A2A receptors associated with carotid bodies trigger hypoxic cardiovascular chemoreflexes, while central A2A receptors mediate hypoxic inhibition of breathing and rapid eye movements. A2A receptors are also involved in hypoxic regulation of fetal endocrine systems, metabolism, and vascular tone. In developing lambs, A2A receptors play virtually no role in O2 sensing by the carotid bodies, but brain A2A receptors remain critically involved in the roll-off ventilatory response to hypoxia. In adult mammals, A2A receptors have been implicated in O2 sensing by carotid glomus cells, while central A2A receptors likely blunt hypoxic hyperventilation. In conclusion, A2A receptors are crucially involved in the transduction mechanisms of O2 sensing in fetal carotid bodies and brains. Postnatally, central A2A receptors remain key mediators of hypoxic respiratory depression, but they are less critical for O2 sensing in carotid chemoreceptors, particularly in developing lambs. PMID:21677265

Microenvironmental oxygen partial pressure in acute myeloid leukemia: Is there really a role for hypoxia?

PubMed

Rieger, Christina T; Fiegl, Michael

2016-07-01

Reduced oxygen partial pressure (pO2) has been recognized as being relevant in hematopoiesis and the pathophysiology of malignant diseases. Although hypoxic (meaning insufficient supply of oxygen) and anoxic areas are present and of pathophysiologic importance (by hypoxia-induced pathways such as HiF1α) in solid tumors, this may not be true for (malignant) hematologic cells. Hematopoiesis occurs in the stem cell niche, which is characterized, among other things, by extremely low pO2. However, in contrast to solid tumors, in this context, the low pO2 is physiological and this feature, among others, is shared by the malignant stem cell niche harboring leukemia-initiating cells. Upon differentiation, hematopoietic cells are constantly exposed to changes in pO2 as they travel throughout the human body and encounter arterial and venous blood and migrate into oxygen-carrier-free tissue with low pO2. Hematologic malignancies such as acute myeloid leukemia (AML) make little difference in this respect and, whereas low oxygen is the usual environment of AML cells, recent evidence suggests no role for real hypoxia. Although there is no evidence that AML pathophysiology is related to hypoxia, leukemic blasts still show several distinct biological features when exposed to reduced pO2: they down- or upregulate membrane receptors such as CXCR4 or FLT3, activate or inhibit intracellular signaling pathways such as PI3K, and specifically secrete cytokines (IL-8). In summary, reduced pO2 should not be mistaken for hypoxia (nor should it be so called), and it does not automatically induce hypoxia-response mechanisms; therefore, a strict distinction should be made between physiologically low pO2 (physoxia) and hypoxia. Copyright © 2016 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.

High-throughput determination of biochemical oxygen demand (BOD) by a microplate-based biosensor.

PubMed

Pang, Hei-Leung; Kwok, Nga-Yan; Chan, Pak-Ho; Yeung, Chi-Hung; Lo, Waihung; Wong, Kwok-Yin

2007-06-01

The use of the conventional 5-day biochemical oxygen demand (BOD5) method in BOD determination is greatly hampered by its time-consuming sampling procedure and its technical difficulty in the handling of a large pool of wastewater samples. Thus, it is highly desirable to develop a fast and high-throughput biosensor for BOD measurements. This paper describes the construction of a microplate-based biosensor consisting of an organically modified silica (ORMOSIL) oxygen sensing film for high-throughput determination of BOD in wastewater. The ORMOSIL oxygen sensing film was prepared by reacting tetramethoxysilane with dimethyldimethoxysilane in the presence of the oxygen-sensitive dye tris(4,7-diphenyl-1,10-phenanthroline)ruthenium-(II) chloride. The silica composite formed a homogeneous, crack-free oxygen sensing film on polystyrene microtiter plates with high stability, and the embedded ruthenium dye interacted with the dissolved oxygen in wastewater according to the Stern-Volmer relation. The bacterium Stenotrophomonas maltophilia was loaded into the ORMOSIL/ PVA composite (deposited on the top of the oxygen sensing film) and used to metabolize the organic compounds in wastewater. This BOD biosensor was found to be able to determine the BOD values of wastewater samples within 20 min by monitoring the dissolved oxygen concentrations. Moreover, the BOD values determined by the BOD biosensor were in good agreement with those obtained by the conventional BOD5 method.

Acute health impacts of airborne particles estimated from satellite remote sensing.

PubMed

Wang, Zhaoxi; Liu, Yang; Hu, Mu; Pan, Xiaochuan; Shi, Jing; Chen, Feng; He, Kebin; Koutrakis, Petros; Christiani, David C

2013-01-01

Satellite-based remote sensing provides a unique opportunity to monitor air quality from space at global, continental, national and regional scales. Most current research focused on developing empirical models using ground measurements of the ambient particulate. However, the application of satellite-based exposure assessment in environmental health is still limited, especially for acute effects, because the development of satellite PM(2.5) model depends on the availability of ground measurements. We tested the hypothesis that MODIS AOD (aerosol optical depth) exposure estimates, obtained from NASA satellites, are directly associated with daily health outcomes. Three independent healthcare databases were used: unscheduled outpatient visits, hospital admissions, and mortality collected in Beijing metropolitan area, China during 2006. We use generalized linear models to compare the short-term effects of air pollution assessed by ground monitoring (PM(10)) with adjustment of absolute humidity (AH) and AH-calibrated AOD. Across all databases we found that both AH-calibrated AOD and PM(10) (adjusted by AH) were consistently associated with elevated daily events on the current day and/or lag days for cardiovascular diseases, ischemic heart diseases, and COPD. The relative risks estimated by AH-calibrated AOD and PM(10) (adjusted by AH) were similar. Additionally, compared to ground PM(10), we found that AH-calibrated AOD had narrower confidence intervals for all models and was more robust in estimating the current day and lag day effects. Our preliminary findings suggested that, with proper adjustment of meteorological factors, satellite AOD can be used directly to estimate the acute health impacts of ambient particles without prior calibrating to the sparse ground monitoring networks. Copyright © 2012 Elsevier Ltd. All rights reserved.

Treatment of Adenoviral Acute Respiratory Distress Syndrome Using Cidofovir With Extracorporeal Membrane Oxygenation.

PubMed

Lee, Minhyeok; Kim, Seulgi; Kwon, Oh Jung; Kim, Ji Hye; Jeong, Inbeom; Son, Ji Woong; Na, Moon Jun; Yoon, Yoo Sang; Park, Hyun Woong; Kwon, Sun Jung

2017-03-01

Adenovirus infections are associated with respiratory (especially upper respiratory) infection and gastrointestinal disease and occur primarily in infants and children. Although rare in adults, severe lower respiratory adenovirus infections including pneumonia are reported in specific populations, such as military recruits and immunocompromised patients. Antiviral treatment is challenging due to limited clinical experience and lack of well-controlled randomized trials. Several previously reported cases of adenoviral pneumonia showed promising efficacy of cidofovir. However, few reports discussed the efficacy of cidofovir in acute respiratory distress syndrome (ARDS). We experienced 3 cases of adenoviral pneumonia associated with ARDS and treated with cidofovir and respiratory support, including extracorporeal membrane oxygenation (ECMO). All 3 patients showed a positive clinical response to cidofovir and survival at 28 days. Cidofovir with early ECMO therapy may be a therapeutic option in adenoviral ARDS. A literature review identified 15 cases of adenovirus pneumonia associated with ARDS.

FRET excited ratiometric oxygen sensing in living tissue

PubMed Central

Ingram, Justin M.; Zhang, Chunfeng; Xu, Jian; Schiff, Steven J.

2013-01-01

Dynamic analysis of oxygen (O2) has been limited by the lack of a real-time, quantitative, and biocompatible sensor. To address these demands, we designed a ratiometric optode matrix consisting of the phosphorescence quenching dye platinum (II) octaethylporphine ketone (PtOEPK) and nanocystal quantum dots (NQDs), which when embedded within an inert polymer matrix allows long-term pre-designed excitation through fluorescence resonance energy transfer (FRET). Depositing this matrix on various glass substrates allowed the development of a series of optical sensors able to measure interstitial oxygen concentration [O2] with several hundred millisecond temporal resolution in varying biological microdomains of active brain tissue. PMID:23333398

A Distributed Chemosensory Circuit for Oxygen Preference in C. elegans

PubMed Central

Chang, Andy J; Chronis, Nikolas; Karow, David S; Marletta, Michael A; Bargmann, Cornelia I

2006-01-01

The nematode Caenorhabditis elegans has complex, naturally variable behavioral responses to environmental oxygen, food, and other animals. C. elegans detects oxygen through soluble guanylate cyclase homologs (sGCs) and responds to it differently depending on the activity of the neuropeptide receptor NPR-1: npr-1(lf) and naturally isolated npr-1(215F) animals avoid high oxygen and aggregate in the presence of food; npr-1(215V) animals do not. We show here that hyperoxia avoidance integrates food with npr-1 activity through neuromodulation of a distributed oxygen-sensing network. Hyperoxia avoidance is stimulated by sGC-expressing oxygen-sensing neurons, nociceptive neurons, and ADF sensory neurons. In npr-1(215V) animals, the switch from weak aerotaxis on food to strong aerotaxis in its absence requires close regulation of the neurotransmitter serotonin in the ADF neurons; high levels of ADF serotonin promote hyperoxia avoidance. In npr-1(lf) animals, food regulation is masked by increased activity of the oxygen-sensing neurons. Hyperoxia avoidance is also regulated by the neuronal TGF-β homolog DAF-7, a secreted mediator of crowding and stress responses. DAF-7 inhibits serotonin synthesis in ADF, suggesting that ADF serotonin is a convergence point for regulation of hyperoxia avoidance. Coalitions of neurons that promote and repress hyperoxia avoidance generate a subtle and flexible response to environmental oxygen. PMID:16903785

Monitoring Intracellular Oxygen Concentration: Implications for Hypoxia Studies and Real-Time Oxygen Monitoring.

PubMed

Potter, Michelle; Badder, Luned; Hoade, Yvette; Johnston, Iain G; Morten, Karl J

2016-01-01

The metabolic properties of cancer cells have been widely accepted as a hallmark of cancer for a number of years and have shown to be of critical importance in tumour development. It is generally accepted that tumour cells exhibit a more glycolytic phenotype than normal cells. In this study, we investigate the bioenergetic phenotype of two widely used cancer cell lines, RD and U87MG, by monitoring intracellular oxygen concentrations using phosphorescent Pt-porphyrin based intracellular probes. Our study demonstrates that cancer cell lines do not always exhibit an exclusively glycolytic phenotype. RD demonstrates a reliance on oxidative phosphorylation whilst U87MG display a more glycolytic phenotype. Using the intracellular oxygen sensing probe we generate an immediate readout of intracellular oxygen levels, with the glycolytic lines reflecting the oxygen concentration of the environment, and cells with an oxidative phenotype having significantly lower levels of intracellular oxygen. Inhibition of oxygen consumption in lines with high oxygen consumption increases intracellular oxygen levels towards environmental levels. We conclude that the use of intracellular oxygen probes provides a quantitative assessment of intracellular oxygen levels, allowing the manipulation of cellular bioenergetics to be studied in real time.

Intra-breath arterial oxygen oscillations detected by a fast oxygen sensor in an animal model of acute respiratory distress syndrome

PubMed Central

Formenti, F.; Chen, R.; McPeak, H.; Murison, P. J.; Matejovic, M.; Hahn, C. E. W.; Farmery, A. D.

2015-01-01

Background There is considerable interest in oxygen partial pressure (Po2) monitoring in physiology, and in tracking Po2 changes dynamically when it varies rapidly. For example, arterial Po2 (PaO2) can vary within the respiratory cycle in cyclical atelectasis (CA), where PaO2 is thought to increase and decrease during inspiration and expiration, respectively. A sensor that detects these PaO2 oscillations could become a useful diagnostic tool of CA during acute respiratory distress syndrome (ARDS). Methods We developed a fibreoptic Po2 sensor (<200 µm diameter), suitable for human use, that has a fast response time, and can measure Po2 continuously in blood. By altering the inspired fraction of oxygen (FIO2) from 21 to 100% in four healthy animal models, we determined the linearity of the sensor's signal over a wide range of PaO2 values in vivo. We also hypothesized that the sensor could measure rapid intra-breath PaO2 oscillations in a large animal model of ARDS. Results In the healthy animal models, PaO2 responses to changes in FIO2 were in agreement with conventional intermittent blood-gas analysis (n=39) for a wide range of PaO2 values, from 10 to 73 kPa. In the animal lavage model of CA, the sensor detected PaO2 oscillations, also at clinically relevant PaO2 levels close to 9 kPa. Conclusions We conclude that these fibreoptic PaO2 sensors have the potential to become a diagnostic tool for CA in ARDS. PMID:25631471

Pericellular oxygen monitoring with integrated sensor chips for reproducible cell culture experiments.

PubMed

Kieninger, J; Aravindalochanan, K; Sandvik, J A; Pettersen, E O; Urban, G A

2014-04-01

Here we present an application, in two tumour cell lines, based on the Sensing Cell Culture Flask system as a cell culture monitoring tool for pericellular oxygen sensing. T-47D (human breast cancer) and T98G (human brain cancer) cells were cultured either in atmospheric air or in a glove-box set at 4% oxygen, in both cases with 5% CO2 in the gas phase. Pericellular oxygen tension was measured with the help of an integrated sensor chip comprising oxygen sensor arrays. Obtained results illustrate variation of pericellular oxygen tension in attached cells covered by stagnant medium. Independent of incubation conditions, low pericellular oxygen concentration levels, usually associated with hypoxia, were found in dense cell cultures. Respiration alone brought pericellular oxygen concentration down to levels which could activate hypoxia-sensing regulatory processes in cultures believed to be aerobic. Cells in culture believed to experience conditions of mild hypoxia may, in reality, experience severe hypoxia. This would lead to incorrect assumptions and suggests that pericellular oxygen concentration readings are of great importance to obtain reproducible results when dealing with hypoxic and normoxic (aerobic) incubation conditions. The Sensing Cell Culture Flask system allows continuous monitoring of pericellular oxygen concentration with outstanding long-term stability and no need for recalibration during cell culture experiments. The sensor is integrated into the flask bottom, thus in direct contact with attached cells. No additional equipment needs to be inserted into the flask during culturing. Transparency of the electrochemical sensor chip allows optical inspection of cells attached on top of the sensor. © 2014 John Wiley & Sons Ltd.

Nitric oxide is a versatile sensor of low oxygen stress in plants

PubMed Central

Borisjuk, Ljudmilla

2008-01-01

The plant response to low levels of oxygen involves an interplay of transcriptional, translational and post-translational signaling. However, in plants, the sensing mechanism itself remains obscure. The role of nitric oxide (NO) in oxygen sensing and balancing has been extensively explored in our laboratory. We suggest that NO is generated within the mitochondria from nitrite in response to hypoxia, and that this small gaseous molecule can reversibly modify both the respiratory oxygen consumption and the oxygen availability within the seed. We further propose that hemoglobins play a central role in the detoxification of excess NO. PMID:19704575

The medical use of oxygen: a time for critical reappraisal.

PubMed

Sjöberg, F; Singer, M

2013-12-01

Oxygen treatment has been a cornerstone of acute medical care for numerous pathological states. Initially, this was supported by the assumed need to avoid hypoxaemia and tissue hypoxia. Most acute treatment algorithms, therefore, recommended the liberal use of a high fraction of inspired oxygen, often without first confirming the presence of a hypoxic insult. However, recent physiological research has underlined the vasoconstrictor effects of hyperoxia on normal vasculature and, consequently, the risk of significant blood flow reduction to the at-risk tissue. Positive effects may be claimed simply by relief of an assumed local tissue hypoxia, such as in acute cardiovascular disease, brain ischaemia due to, for example, stroke or shock or carbon monoxide intoxication. However, in most situations, a generalized hypoxia is not the problem and a risk of negative hyperoxaemia-induced local vasoconstriction effects may instead be the reality. In preclinical studies, many important positive anti-inflammatory effects of both normobaric and hyperbaric oxygen have been repeatedly shown, often as surrogate end-points such as increases in gluthatione levels, reduced lipid peroxidation and neutrophil activation thus modifying ischaemia-reperfusion injury and also causing anti-apoptotic effects. However, in parallel, toxic effects of oxygen are also well known, including induced mucosal inflammation, pneumonitis and retrolental fibroplasia. Examining the available 'strong' clinical evidence, such as usually claimed for randomized controlled trials, few positive studies stand up to scrutiny and a number of trials have shown no effect or even been terminated early due to worse outcomes in the oxygen treatment arm. Recently, this has led to less aggressive approaches, even to not providing any supplemental oxygen, in several acute care settings, such as resuscitation of asphyxiated newborns, during acute myocardial infarction or after stroke or cardiac arrest. The safety of more

Noninvasive oxygen monitoring techniques.

PubMed

Wahr, J A; Tremper, K K

1995-01-01

As this article demonstrates, tremendous progress has been made in the techniques of oxygen measurement and monitoring over the past 50 years. From the early developments during and after World War II, to the most recent applications of solid state and microprocessor technology today, every patient in a critical care situation will have several continuous measurements of oxygenation applied simultaneously. Information therefore is available readily to alert personnel of acute problems and to guide appropriate therapy. The majority of effort to date has been placed on measuring oxygenation of arterial or venous blood. The next generation of devices will attempt to provide information about living tissue. Unlike the devices monitoring arterial or venous oxygen content, no "gold standards" exist for tissue oxygenation, so calibration will be difficult, as will interpretation of the data provided. The application of these devices ultimately may lead to a much better understanding of how disease (and the treatment of disease) alters the utilization of oxygen by the tissues.

Effectiveness and Safety of High-Flow Nasal Cannula Oxygen Delivery during Bronchoalveolar Lavage in Acute Respiratory Failure Patients.

PubMed

Kim, Eun Jin; Jung, Chi Young; Kim, Kyung Chan

2018-06-19

Bronchoalveolar lavage (BAL) is a necessary procedure for diagnosis of various lung diseases. High-flow nasal cannula (HFNC) oxygen delivery was recently introduced. This study aimed to investigate the safety and effectiveness of HFNC oxygen supply during BAL procedure in patients with acute respiratory failure (ARF). Patients who underwent BAL while using HFNC at a partial pressure of oxygen in arterial blood/fraction of inspired oxygen (PaO₂/FiO₂; PF) ratio of 300 or below among patients who had been admitted from March 2013 to May 2017 were retrospectively investigated. Thirty-three BAL procedures were confirmed. Their baseline PF ratio was 166.1±46.7. FiO₂ values before, during, and after BAL were 0.45±0.12, 0.74±0.19, and 0.57±0.14, respectively. Flow (L/min) values before, during, and after BAL were 26.5±20.3, 49.0±7.2, and 40.8±14.2, respectively. Both FiO₂ and flow during and after the procedure were significantly different from those before the procedure (both p<0.001). Oxygen saturation levels before, during, and after BAL measured by pulse oximeter were 94.8±2.9, 94.6±3.5, and 95.2±2.8%, respectively. There were no significant differences in oxygen saturation among the three groups. Complications of BAL procedure included transient hypoxemia, hypotension, and fever. However, there was no endotracheal intubation within 24 hours. Baseline PF ratio in "without HFNC" group was significantly higher than that in "with HFNC" group. There were no differences in complications between the two groups. The use of HFNC during BAL procedure in ARF patients was effective and safe. However, there were no significant differences in oxygen saturation level and complications comparing "without HFNC" group in mild ARF. More studies are needed for moderate to severe ARF patients. Copyright©2018. The Korean Academy of Tuberculosis and Respiratory Diseases.

Mechanical Ventilation during Extracorporeal Membrane Oxygenation in Patients with Acute Severe Respiratory Failure.

PubMed

Zhang, Zhongheng; Gu, Wan-Jie; Chen, Kun; Ni, Hongying

2017-01-01

Conventionally, a substantial number of patients with acute respiratory failure require mechanical ventilation (MV) to avert catastrophe of hypoxemia and hypercapnia. However, mechanical ventilation per se can cause lung injury, accelerating the disease progression. Extracorporeal membrane oxygenation (ECMO) provides an alternative to rescue patients with severe respiratory failure that conventional mechanical ventilation fails to maintain adequate gas exchange. The physiology behind ECMO and its interaction with MV were reviewed. Next, we discussed the timing of ECMO initiation based on the risks and benefits of ECMO. During the running of ECMO, the protective ventilation strategy can be employed without worrying about catastrophic hypoxemia and carbon dioxide retention. There is a large body of evidence showing that protective ventilation with low tidal volume, high positive end-expiratory pressure, and prone positioning can provide benefits on mortality outcome. More recently, there is an increasing popularity on the use of awake and spontaneous breathing for patients undergoing ECMO, which is thought to be beneficial in terms of rehabilitation.

Mechanical Ventilation during Extracorporeal Membrane Oxygenation in Patients with Acute Severe Respiratory Failure

PubMed Central

Gu, Wan-Jie; Chen, Kun; Ni, Hongying

2017-01-01

Conventionally, a substantial number of patients with acute respiratory failure require mechanical ventilation (MV) to avert catastrophe of hypoxemia and hypercapnia. However, mechanical ventilation per se can cause lung injury, accelerating the disease progression. Extracorporeal membrane oxygenation (ECMO) provides an alternative to rescue patients with severe respiratory failure that conventional mechanical ventilation fails to maintain adequate gas exchange. The physiology behind ECMO and its interaction with MV were reviewed. Next, we discussed the timing of ECMO initiation based on the risks and benefits of ECMO. During the running of ECMO, the protective ventilation strategy can be employed without worrying about catastrophic hypoxemia and carbon dioxide retention. There is a large body of evidence showing that protective ventilation with low tidal volume, high positive end-expiratory pressure, and prone positioning can provide benefits on mortality outcome. More recently, there is an increasing popularity on the use of awake and spontaneous breathing for patients undergoing ECMO, which is thought to be beneficial in terms of rehabilitation. PMID:28127231

Logarithmic sensing in Bacillus subtilis aerotaxis.

PubMed

Menolascina, Filippo; Rusconi, Roberto; Fernandez, Vicente I; Smriga, Steven; Aminzare, Zahra; Sontag, Eduardo D; Stocker, Roman

2017-01-01

Aerotaxis, the directed migration along oxygen gradients, allows many microorganisms to locate favorable oxygen concentrations. Despite oxygen's fundamental role for life, even key aspects of aerotaxis remain poorly understood. In Bacillus subtilis, for example, there is conflicting evidence of whether migration occurs to the maximal oxygen concentration available or to an optimal intermediate one, and how aerotaxis can be maintained over a broad range of conditions. Using precisely controlled oxygen gradients in a microfluidic device, spanning the full spectrum of conditions from quasi-anoxic to oxic (60 n mol/l-1 m mol/l), we resolved B. subtilis' 'oxygen preference conundrum' by demonstrating consistent migration towards maximum oxygen concentrations ('monotonic aerotaxis'). Surprisingly, the strength of aerotaxis was largely unchanged over three decades in oxygen concentration (131 n mol/l-196 μ mol/l). We discovered that in this range B. subtilis responds to the logarithm of the oxygen concentration gradient, a rescaling strategy called 'log-sensing' that affords organisms high sensitivity over a wide range of conditions. In these experiments, high-throughput single-cell imaging yielded the best signal-to-noise ratio of any microbial taxis study to date, enabling the robust identification of the first mathematical model for aerotaxis among a broad class of alternative models. The model passed the stringent test of predicting the transient aerotactic response despite being developed on steady-state data, and quantitatively captures both monotonic aerotaxis and log-sensing. Taken together, these results shed new light on the oxygen-seeking capabilities of B. subtilis and provide a blueprint for the quantitative investigation of the many other forms of microbial taxis.

A wearable conformal bandage for non-invasive two-dimensional imaging of skin oxygenation (Conference Presentation)

NASA Astrophysics Data System (ADS)

Li, Zongxi; Roussakis, Emmanuel; Keeley, Emily; Apiou-Sbirlea, Gabriela; Birngruber, Reginald; Huang, Christene; Evans, Conor L.

2016-03-01

The complex surface topology and soft mechanics of the skin poses a considerable challenge to the development of wearable, conformal sensors. As a results, current clinical assessments of healing-related skin parameters often rely on bulky and expensive optical systems that are difficult to deploy at the point of care. Here, using a rapid-drying, liquid bandage containing oxygen-sensing molecules, we created a wearable sensor bandage that conforms the surface geometry of skin and wounds, and provides two-dimensional maps of cutaneous oxygenation in a non-disruptive fashion. Custom oxygen sensing phosphors have been developed in house that are at least five times brighter than the commercial sensing molecules, enabling the visualization of oxygen concentration using a simple color camera or even by eye under ambient lighting conditions. The oxygen-sensing bandage has been applied to monitor tissue ischemia, graft integration, as well as the progression of burn in animal models. Recent studies have demonstrated its ability to track and quantify skin inflammation induced by complete Freund's adjuvant in an in vivo porcine model.

Physiological complexity of acute traumatic brain injury in patients treated with a brain oxygen protocol: utility of symbolic regression in predictive modeling of a dynamical system.

PubMed

Narotam, Pradeep K; Morrison, John F; Schmidt, Michael D; Nathoo, Narendra

2014-04-01

Predictive modeling of emergent behavior, inherent to complex physiological systems, requires the analysis of large complex clinical data streams currently being generated in the intensive care unit. Brain tissue oxygen protocols have yielded outcome benefits in traumatic brain injury (TBI), but the critical physiological thresholds for low brain oxygen have not been established for a dynamical patho-physiological system. High frequency, multi-modal clinical data sets from 29 patients with severe TBI who underwent multi-modality neuro-clinical care monitoring and treatment with a brain oxygen protocol were analyzed. The inter-relationship between acute physiological parameters was determined using symbolic regression (SR) as the computational framework. The mean patient age was 44.4±15 with a mean admission GCS of 6.6±3.9. Sixty-three percent sustained motor vehicle accidents and the most common pathology was intra-cerebral hemorrhage (50%). Hospital discharge mortality was 21%, poor outcome occurred in 24% of patients, and good outcome occurred in 56% of patients. Criticality for low brain oxygen was intracranial pressure (ICP) ≥22.8 mm Hg, for mortality at ICP≥37.1 mm Hg. The upper therapeutic threshold for cerebral perfusion pressure (CPP) was 75 mm Hg. Eubaric hyperoxia significantly impacted partial pressure of oxygen in brain tissue (PbtO2) at all ICP levels. Optimal brain temperature (Tbr) was 34-35°C, with an adverse effect when Tbr≥38°C. Survivors clustered at [Formula: see text] Hg vs. non-survivors [Formula: see text] 18 mm Hg. There were two mortality clusters for ICP: High ICP/low PbtO2 and low ICP/low PbtO2. Survivors maintained PbtO2 at all ranges of mean arterial pressure in contrast to non-survivors. The final SR equation for cerebral oxygenation is: [Formula: see text]. The SR-model of acute TBI advances new physiological thresholds or boundary conditions for acute TBI management: PbtO2≥25 mmHg; ICP≤22 mmHg; CPP≈60-75�

Acute administration of tumour necrosis factor-α induces spontaneous calcium release via the reactive oxygen species pathway in atrial myocytes.

PubMed

Zuo, Song; Li, Lin-Ling; Ruan, Yan-Fei; Jiang, Le; Li, Xin; Li, Song-Nan; Wen, Song-Nan; Bai, Rong; Liu, Nian; Du, Xin; Dong, Jian-Zeng; Ma, Chang-Sheng

2017-10-17

The arrhythmogenic mechanisms of atrial fibrillation (AF) that are induced by acute inflammation, such as postoperative AF, are not well understood. We investigated the acute effects of tumour necrosis factor-α (TNF-α) that mimic acute inflammation on Ca2+ handling in isolated atrial myocytes and its underlying mechanisms. Cytosol Ca2+ handling and mitochondrial reactive oxygen species (ROS) production were studied in freshly isolated atrial myocytes of wild-type mice that were exposed to TNF-α (0.05 ng/mL) for 2 h by Ionoptix and confocal microscopy. The acute effects of TNF-α on Ca2+ handling were decreased amplitudes and prolonged decay times of Ca2+ transients in isolated atrial myocytes. A significant reduction in the sarcoplasmic reticulum (SR) Ca2+ content was detected in TNF-α treated cells, which was associated with increased spontaneous Ca2+ release events. In particular, physiological concentrations of TNF-α dramatically promoted the frequency of spontaneous Ca2+ waves and Ca2+ sparks, while the spark mass presented with reduced amplitudes and prolonged durations. The underlying mechanisms of pro-arrhythmic effects of TNF-α were further investigated. Acute exposure to TNF-α rapidly promoted mitochondrial ROS production that was correlated with the acute effect of TNF-α on Ca2+ handling, and enhanced the oxidation of calcium/calmodulin-dependent protein kinase II (CaMKII) and the phosphorylation of RyR2. However, the performance of ROS inhibitor, DL-Dithiothreitol (DTT), reversed Ca2+ handling disorders induced by TNF-α. Tumour necrosis factor-α rapidly increases spontaneous Ca2+ release and promotes atrial arrhythmogenesis via the ROS pathway, which suggests that antioxidant therapy is a promising strategy for acute inflammation related AF. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Calcium and Reactive Oxygen Species in Acute Pancreatitis: Friend or Foe?

PubMed Central

Booth, David M.; Mukherjee, Rajarshi; Sutton, Robert

2011-01-01

Abstract Significance Acute pancreatitis (AP) is a debilitating and, at times, lethal inflammatory disease, the causes and progression of which are incompletely understood. Disruption of Ca2+ homeostasis in response to precipitants of AP leads to loss of mitochondrial integrity and cellular necrosis. Recent Advances While oxidative stress has been implicated as a major player in the pathogenesis of this disease, its precise roles remain to be defined. Recent developments are challenging the perception of reactive oxygen species (ROS) as nonspecific cytotoxic agents, suggesting that ROS promote apoptosis that may play a vital protective role in cellular stress since necrosis is avoided. Critical Issues Fresh clinical findings have indicated that antioxidant treatment does not ameliorate AP and may actually worsen the outcome. This review explores the complex links between cellular Ca2+ signaling and the intracellular redox environment, with particular relevance to AP. Future Directions Recent publications have underlined the importance of both Ca2+ and ROS within the pathogenesis of AP, particularly in the determination of cell fate. Future research should elucidate the subtle interplay between Ca2+ and redox mechanisms that operate to modulate mitochondrial function, with a view to devising strategies for the preservation of organellar function. Antioxid. Redox Signal. 15, 2683–2698. PMID:21861696

Patient positioning influences oxygen saturation in the acute phase of stroke.

PubMed

Rowat, A M; Wardlaw, J M; Dennis, M S; Warlow, C P

2001-01-01

We evaluated arterial oxygen saturation (SaO(2)) and heart rate in acute stroke patients to determine whether routine positioning affected these physiological parameters. Measurements were recorded at the bedside non-invasively in five different positions assigned in random order each maintained for 10 min. One hundred and twenty-nine patients examined within a median of 72 h, lying on the left side resulted in slightly lower SaO(2) than lying on the right side, which was statistically significant in the patients with a right (n = 66), but not left, hemiparesis. Patients able to sit in a chair (n = 65), who mostly had less severe strokes, had a significantly higher mean SaO(2) and heart rate when sitting in the chair than when placed in any other position. About 10% of patients, especially those with a severe stroke, with right hemiparesis and concomitant chest disease, experienced falls in SaO(2) to 90% or less for >/=2 min in certain positions; the hypoxia was more likely when they were lying on their left side. These results may have implications for current practice and for future patient positioning strategies to improve outcome after stroke. Copyright 2001 S. Karger AG, Basel

Catabolite and Oxygen Regulation of Enterohemorrhagic Escherichia coli Virulence.

PubMed

Carlson-Banning, Kimberly M; Sperandio, Vanessa

2016-11-22

The biogeography of the gut is diverse in its longitudinal axis, as well as within specific microenvironments. Differential oxygenation and nutrient composition drive the membership of microbial communities in these habitats. Moreover, enteric pathogens can orchestrate further modifications to gain a competitive advantage toward host colonization. These pathogens are versatile and adept when exploiting the human colon. They expertly navigate complex environmental cues and interkingdom signaling to colonize and infect their hosts. Here we demonstrate how enterohemorrhagic Escherichia coli (EHEC) uses three sugar-sensing transcription factors, Cra, KdpE, and FusR, to exquisitely regulate the expression of virulence factors associated with its type III secretion system (T3SS) when exposed to various oxygen concentrations. We also explored the effect of mucin-derived nonpreferred carbon sources on EHEC growth and expression of virulence genes. Taken together, the results show that EHEC represses the expression of its T3SS when oxygen is absent, mimicking the largely anaerobic lumen, and activates its T3SS when oxygen is available through Cra. In addition, when EHEC senses mucin-derived sugars heavily present in the O-linked and N-linked glycans of the large intestine, virulence gene expression is initiated. Sugars derived from pectin, a complex plant polysaccharide digested in the large intestine, also increased virulence gene expression. Not only does EHEC sense host- and microbiota-derived interkingdom signals, it also uses oxygen availability and mucin-derived sugars liberated by the microbiota to stimulate expression of the T3SS. This precision in gene regulation allows EHEC to be an efficient pathogen with an extremely low infectious dose. Enteric pathogens have to be crafty when interpreting multiple environmental cues to successfully establish themselves within complex and diverse gut microenvironments. Differences in oxygen tension and nutrient composition

Sensing and imaging of oxygen with parts per billion limits of detection and based on the quenching of the delayed fluorescence of (13)C70 fullerene in polymer hosts.

PubMed

Kochmann, Sven; Baleizão, Carlos; Berberan-Santos, Mário N; Wolfbeis, Otto S

2013-02-05

We report on a new method for sensing trace oxygen in the gas phase. It is based on the extreme efficiency of the quenching of the thermally activated delayed fluorescence of isotopically enriched carbon-13 fullerene C(70) ((13)C(70)). This fullerene was dissolved in polymer matrixes of varying oxygen permeability, viz., polystyrene (PS), ethyl cellulose (EC) and an organically modified silica gel ("ormosil"; OS). The sensor films (5-10 μm thick), on photoexcitation at 470 nm, display a strong delayed photoluminescence with peaks between 670 and 700 nm. Its quenching by molecular oxygen was studied at 25 and 60 °C and at concentrations from zero up to 150 ppmv of oxygen in nitrogen. The rapid lifetime determination (RLD) method was applied to determine oxygen-dependent lifetimes and for fluorescence lifetime imaging of oxygen. The lower limits of detection (at 1% quenching) vary with the polymer used (EC ∼250 ppbv, OS ∼320 ppbv, PS ∼530 ppbv at 25 °C) and with temperature. The oxygen sensors reported here are the most sensitive ones described so far.

Horseradish Peroxidase-Encapsulated Hollow Silica Nanospheres for Intracellular Sensing of Reactive Oxygen Species

NASA Astrophysics Data System (ADS)

Chen, Hsin-Yi; Wu, Si-Han; Chen, Chien-Tsu; Chen, Yi-Ping; Chang, Feng-Peng; Chien, Fan-Ching; Mou, Chung-Yuan

2018-04-01

Reactive oxygen species (ROS) have crucial roles in cell signaling and homeostasis. Overproduction of ROS can induce oxidative damage to various biomolecules and cellular structures. Therefore, developing an approach capable of monitoring and quantifying ROS in living cells is significant for physiology and clinical diagnoses. Some cell-permeable fluorogenic probes developed are useful for the detection of ROS while in conjunction with horseradish peroxidase (HRP). Their intracellular scenario is however hindered by the membrane-impermeable property of enzymes. Herein, a new approach for intracellular sensing of ROS by using horseradish peroxidase-encapsulated hollow silica nanospheres (designated HRP@HSNs), with satisfactory catalytic activity, cell membrane permeability, and biocompatibility, was prepared via a microemulsion method. These HRP@HSNs, combined with selective probes or targeting ligands, could be foreseen as ROS-detecting tools in specific organelles or cell types. As such, dihydrorhodamine 123-coupled HRP@HSNs were used for the qualitative and semi-quantitative analysis of physiological H2O2 levels in activated RAW 264.7 macrophages. We envision that this HSNs encapsulating active enzymes can be conjugated with selective probes and targeting ligands to detect ROS in specific organelles or cell types of interest.

Predicting the Occurrence of Oxygenation Impairment in Patients with Type-B Acute Aortic Dissection

PubMed Central

Tomita, Kazunori; Hata, Noritake; Kobayashi, Nobuaki; Shinada, Takuro; Shirakabe, Akihiro

2014-01-01

Complicated respiratory failure requiring mechanical ventilation in patients with type-B acute aortic dissection (AAD) has been previously reported, and inflammatory reactions have been found to be associated with the occurrence of oxygenation impairment (OI). However, the possibility of predicting the occurrence of OI in patients with type-B AAD has not yet been evaluated. This study was performed to investigate the possibility of predicting the occurrence of OI in type-B AAD. In this study, 79 type-B AAD patients were enrolled to investigate the possibility of predicting the occurrence of OI. OI was defined as Po 2/Fio 2 ≤ 200. Patient characteristics, type of AAD, vital signs on admission, and the presence of inflammatory reactions obtained on admission day were evaluated. OI occurred in 39 patients (49%) on hospital day 2.5 ± 1.4 on average. Younger age, male gender, nonslender frame (body mass index ≥ 22 kg/m2), a relatively high maximum body temperature on the admission day (≥ 36.5°C), DeBakey IIIb type, patent false lumen, and lower Po 2/Fio 2 on admission were found to be associated with the occurrence of OI. Multivariate analysis revealed that nonslender frame, relatively high body temperature on the admission day, and lower Po 2/Fio 2 on admission were reliable for predicting the occurrence of oxygen impairment. The occurrence of OI in type-B AAD can be predicted in the clinical setting. PMID:24627618

Schopenhauer on Sense Perception and Aesthetic Cognition

ERIC Educational Resources Information Center

Vandenabeele, Bart

2011-01-01

Schopenhauer's account of sense perception contains an acute critique of Kant's theory of cognition. His analysis of the role of the understanding in perception may be closer to Kant's than he conceded, but his physiological analysis of the role of the senses nonetheless proffers a more plausible account than Kant's transcendental conception of…

Structural analysis of an oxygen-regulated diguanylate cyclase.

PubMed

Tarnawski, Miroslaw; Barends, Thomas R M; Schlichting, Ilme

2015-11-01

Cyclic di-GMP is a bacterial second messenger that is involved in switching between motile and sessile lifestyles. Given the medical importance of biofilm formation, there has been increasing interest in understanding the synthesis and degradation of cyclic di-GMPs and their regulation in various bacterial pathogens. Environmental cues are detected by sensing domains coupled to GGDEF and EAL or HD-GYP domains that have diguanylate cyclase and phosphodiesterase activities, respectively, producing and degrading cyclic di-GMP. The Escherichia coli protein DosC (also known as YddV) consists of an oxygen-sensing domain belonging to the class of globin sensors that is coupled to a C-terminal GGDEF domain via a previously uncharacterized middle domain. DosC is one of the most strongly expressed GGDEF proteins in E. coli, but to date structural information on this and related proteins is scarce. Here, the high-resolution structural characterization of the oxygen-sensing globin domain, the middle domain and the catalytic GGDEF domain in apo and substrate-bound forms is described. The structural changes between the iron(III) and iron(II) forms of the sensor globin domain suggest a mechanism for oxygen-dependent regulation. The structural information on the individual domains is combined into a model of the dimeric DosC holoprotein. These findings have direct implications for the oxygen-dependent regulation of the activity of the cyclase domain.

Two-photon oxygen nanosensors based on a conjugated fluorescent polymer doped with platinum porphyrins.

PubMed

Wang, Xiao-Hui; Peng, Hong-Shang; Cheng, Kun; Liu, Xiao-Ming; Liu, Yuan-An; Yang, Wei

2018-04-27

Ratiometric fluorescent nanoparticles (NPs) under two-photon excitation are successfully developed for sensing dissolved oxygen. The NPs comprise the oxygen probe Pt(II)-porphyrins (PtTFPP) and fluorescent organic semiconducting polymer (PFO). PFO polymer acts as both a two-photon antenna and a reference dye, while PtTFPP absorbs the photonic energy transferred by the PFO under two-photon excitation at 740 nm to sense oxygen. The red fluorescence of PtTFPP is sensitive to oxygen with a quenching response of 88% from nitrogen saturation to oxygen saturation, and PFO gives oxygen-insensitive referenced blue fluorescence. The fluorescence quenching of the NPs against oxygen at two-photon excitation follows a linear Stern-Volmer behavior. The nanosensors exhibit low cytotoxic effects as well as effortless cellular uptake. When incorporated into cells, the ratio of the signals increases up to about 500% from oxygen-saturated to oxygen-free environment.

Reactive oxygen species, oxidative stress, glaucoma and hyperbaric oxygen therapy.

PubMed

McMonnies, Charles

This review examines the role of oxidative stress in damage to cells of the trabecular meshwork and associated impaired aqueous drainage as well as damage to retinal ganglion cells and associated visual field losses. Consideration is given to the interaction between vascular and mechanical explanations for pathological changes in glaucoma. For example, elevated intraocular pressure (IOP) forces may contribute to ischaemia but there is increasing evidence that altered blood flow in a wider sense is also involved. Both vascular and mechanical theories are involved through fluctuations in intraocular pressure and dysregulation of blood flow. Retinal function is very sensitive to changes in haemoglobin oxygen concentration and the associated variations in the production of reactive oxygen species. Reperfusion injury and production of reactive oxygen species occurs when IOP is elevated or blood pressure is low and beyond the capacity for blood flow autoregulation to maintain appropriate oxygen concentration. Activities such as those associated with postural changes, muscular effort, eye wiping and rubbing which cause IOP fluctuation, may have significant vascular, mechanical, reperfusion and oxidative stress consequences. Hyperbaric oxygen therapy exposes the eye to increased oxygen concentration and the risk of oxidative damage in susceptible individuals. However, oxygen concentration in aqueous humour, and the risk of damage to trabecular meshwork cells may be greater if hyperbaric oxygen is delivered by a hood which exposes the anterior ocular surface to higher than normal oxygen levels. Oronasal mask delivery of hyperbaric oxygen therapy appears to be indicated in these cases. Copyright © 2017 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Muscle Microvascular Blood Flow, Oxygenation, pH, and Perfusion Pressure Decrease in Simulated Acute Compartment Syndrome.

PubMed

Challa, Sravya T; Hargens, Alan R; Uzosike, Amarachi; Macias, Brandon R

2017-09-06

The current gold standard for diagnosing acute compartment syndrome (ACS) is an assessment of clinical signs, invasive measurement of intramuscular pressure (IMP), and measurement of local perfusion pressure. However, IMP measurements have several shortcomings, including pain, risk of infection, risk of technique error, plugging of the catheter tip, lack of consensus on the diagnostic pressure threshold, and lack of specificity and sensitivity. The objective of this study was to evaluate muscle hemodynamics, oxygenation, and pH as diagnostic parameters in a human model of ACS. We hypothesized that as IMP increases, muscle microvascular blood flow, oxygenation, and pH decrease in the anterior compartment of a leg at heart level and that they decrease significantly more when the leg is elevated further. An external pneumatic leg pressure chamber, combined with a venous stasis thigh cuff, was used to increase IMP and simulate ACS. Eight healthy subjects (5 males and 3 females; mean age, 26 years) had photoplethysmography and near-infrared spectroscopy-pH sensors placed over the middle aspect of the tibialis anterior muscle of the right (experimental) and left (control) legs. Leg chamber pressure conditions (40, 50, and 60 mm Hg) were applied in a randomized order after baseline measurements were taken. Data were collected continuously for each 11-minute pressure condition, with an 11-minute recovery period after each condition, and the average of the last 6 minutes was used for data analyses. The same protocol was repeated with each subject's legs elevated 12 cm above heart level. Data were analyzed using repeated-measures analysis of variance (ANOVA). As IMP increased, muscle microvascular blood flow (p = 0.01), oxygenation (p < 0.001), and pH (p < 0.001) all decreased significantly in the experimental leg compared with the control leg. At all IMP levels, leg elevation significantly decreased muscle oxygenation (p = 0.013) and perfusion pressure (p = 0.03) compared

Enhancing dissolved oxygen control using an on-line hybrid fuzzy-neural soft-sensing model-based control system in an anaerobic/anoxic/oxic process.

PubMed

Huang, Mingzhi; Wan, Jinquan; Hu, Kang; Ma, Yongwen; Wang, Yan

2013-12-01

An on-line hybrid fuzzy-neural soft-sensing model-based control system was developed to optimize dissolved oxygen concentration in a bench-scale anaerobic/anoxic/oxic (A(2)/O) process. In order to improve the performance of the control system, a self-adapted fuzzy c-means clustering algorithm and adaptive network-based fuzzy inference system (ANFIS) models were employed. The proposed control system permits the on-line implementation of every operating strategy of the experimental system. A set of experiments involving variable hydraulic retention time (HRT), influent pH (pH), dissolved oxygen in the aerobic reactor (DO), and mixed-liquid return ratio (r) was carried out. Using the proposed system, the amount of COD in the effluent stabilized at the set-point and below. The improvement was achieved with optimum dissolved oxygen concentration because the performance of the treatment process was optimized using operating rules implemented in real time. The system allows various expert operational approaches to be deployed with the goal of minimizing organic substances in the outlet while using the minimum amount of energy.

Oxygen and the spatial structure of microbial communities.

PubMed

Fenchel, Tom; Finlay, Bland

2008-11-01

Oxygen has two faces. On one side it is the terminal electron acceptor of aerobic respiration - the most efficient engine of energy metabolism. On the other hand, oxygen is toxic because the reduction of molecular O2 creates reactive oxygen species such as the superoxide anion, peroxide, and the hydroxyl radical. Probably most prokaryotes, and virtually all eukaryotes, depend on oxygen respiration, and we show that the ambiguous relation to oxygen is both an evolutionary force and a dominating factor driving functional interactions and the spatial structure of microbial communities.We focus on microbial communities that are specialised for life in concentration gradients of oxygen, where they acquire the full panoply of specific requirements from limited ranges of PO2, which also support the spatial organisation of microbial communities. Marine and lake sediments provide examples of steep O2 gradients, which arise because consumption or production of oxygen exceeds transport rates of molecular diffusion. Deep lakes undergo thermal stratification in warm waters, resulting in seasonal anaerobiosis below the thermocline, and lakes with a permanent pycnocline often have permanent anoxic deep water. The oxycline is here biologically similar to sediments, and it harbours similar microbial biota, the main difference being the spatial scale. In sediments, transport is dominated by molecular diffusion, and in the water column, turbulent mixing dominates vertical transport. Cell size determines the minimum requirement of aerobic organisms. For bacteria (and mitochondria), the half-saturation constant for oxygen uptake ranges within 0.05-0.1% atmospheric saturation; for the amoeba Acanthamoeba castellanii it is 0.2%, and for two ciliate species measuring around 150 microm, it is 1-2 % atmospheric saturation. Protection against O2 toxicity has an energetic cost that increases with increasing ambient O2 tension. Oxygen sensing seems universal in aquatic organisms. Many aspects

Long-term and acute effects of temperature and oxygen on metabolism, food intake, growth and heat tolerance in a freshwater gastropod.

PubMed

Hoefnagel, K Natan; Verberk, Wilco C E P

2017-08-01

Temperature affects the physiology and life-history of ectothermic animals, often increasing metabolic rate and decreasing body size. Oxygen limitation has been put forward as a mechanism to explain thermal responses of body size and the ability to survive stress. However the time-scales involved in growth performance and heat tolerance differ radically. In order to increase our understanding of oxygen and temperature effects on body size and heat tolerance and the time scale involved, we reared Lymnaea stagnalis under six combinations of temperature and oxygen tension from hatching up to an age of 300 days and recorded shell length during this whole period. At the end of this period, we determined scope for growth by measuring food intake rate, assimilation efficiency, respiration rate and ammonium excretion rate at two different temperatures. We also measured the snails' ability to survive heat stress (CTmax), both at normoxia and hypoxia. We found that scope for growth and long term growth performance were much more affected by interactions of chronic oxygen and temperature conditions during rearing than by acute conditions during testing. Furthermore, our study shows that individual variation in growth performance can be traced back to individual differences in rates of food and oxygen consumption. Developmental acclimation also gave rise to differences in CTmax, but these were relatively small and were only expressed when CTmax was tested under hypoxia. The large effects of rearing oxygen conditions on growth and other physiological rates compared to modest effects of test oxygen conditions on CTmax suggest that small effects of hypoxia on the short term (e.g. heat tolerance) may nevertheless have large repercussions on the long term (e.g. growth and reproduction), even in a pulmonate snail that can compensate for hypoxia to some extent by aerial respiration. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of Performance of the Industrial Process of Bulk Vacuum Packaging of Raw Meat with Nondestructive Optical Oxygen Sensing Systems.

PubMed

Kelly, Caroline A; Cruz-Romero, Malco; Kerry, Joseph P; Papkovsky, Dmitri P

2018-05-02

The commercially-available optical oxygen-sensing system Optech-O₂ Platinum was applied to nondestructively assess the in situ performance of bulk, vacuum-packaged raw beef in three ~300 kg containers. Twenty sensors were attached to the inner surface of the standard bin-contained laminate bag (10 on the front and back sides), such that after filling with meat and sealing under vacuum, the sensors were accessible for optical interrogation with the external reader device. After filling and sealing each bag, the sensors were measured repetitively and nondestructively over a 15-day storage period at 1 °C, thus tracking residual oxygen distribution in the bag and changes during storage. The sensors revealed a number of unidentified meat quality and processing issues, and helped to improve the packaging process by pouring flakes of dry ice into the bag. Sensor utility in mapping the distribution of residual O₂ in sealed bulk containers and optimising and improving the packaging process, including handling and storage of bulk vacuum-packaged meat bins, was evident.

A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection

PubMed Central

Hung, San-Shan; Chang, Hsing-Cheng; Chang, I-Nan

2016-01-01

A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2′-bipyridyl) dichlororuthenium(II) hexahydrate and Tris(bipyridine)ruthenium(II) chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%. PMID:27941636

A Portable Array-Type Optical Fiber Sensing Instrument for Real-Time Gas Detection.

PubMed

Hung, San-Shan; Chang, Hsing-Cheng; Chang, I-Nan

2016-12-08

A novel optical fiber array-type of sensing instrument with temperature compensation for real-time detection was developed to measure oxygen, carbon dioxide, and ammonia simultaneously. The proposed instrument is multi-sensing array integrated with real-time measurement module for portable applications. The sensing optical fibers were etched and polished before coating to increase sensitivities. The ammonia and temperature sensors were each composed of a dye-coated single-mode fiber with constructing a fiber Bragg grating and a long-period filter grating for detecting light intensity. Both carbon dioxide and oxygen sensing structures use multimode fibers where 1-hydroxy-3,6,8-pyrene trisulfonic acid trisodium salt is coated for carbon dioxide sensing and Tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate and Tris(bipyridine)ruthenium(II) chloride are coated for oxygen sensing. Gas-induced fluorescent light intensity variation was applied to detect gas concentration. The portable gas sensing array was set up by integrating with photo-electronic measurement modules and a human-machine interface to detect gases in real time. The measured data have been processed using piecewise-linear method. The sensitivity of the oxygen sensor were 1.54%/V and 9.62%/V for concentrations less than 1.5% and for concentrations between 1.5% and 6%, respectively. The sensitivity of the carbon dioxide sensor were 8.33%/V and 9.62%/V for concentrations less than 2% and for concentrations between 2% and 5%, respectively. For the ammonia sensor, the sensitivity was 27.78%/V, while ammonia concentration was less than 2%.

Low-intensity pulsed ultrasound (LIPUS) therapy may enhance the negative effects of oxygen radicals in the acute phase of fracture.

PubMed

Zhao, Xiang; Yan, Shi-Gui

2011-02-01

Though it is well accepted that low-intensity pulsed ultrasound (LIPUS) can accelerate the healing process of a fracture with very good results, we should still pay attention to its side effects and further improve its application in detail, such as the appropriate time and point for the application. In the early phase of a bone fracture, there are millions of oxygen radicals released by neutrophils in the injured area. This article focuses on whether the increased permeability of normal cell membranes by LIPUS makes the concentration of oxygen radicals increase to such a high degree that damage occurs to healthy tissue cells. It is proposed that it may be better not to use LIPUS in the acute phase of a fracture (i.e. within 1week after injury) but instead delay its application until after any inflammatory reaction has weakened to yield better results. Copyright © 2010 Elsevier Ltd. All rights reserved.

Evaluation of acute effect of light-emitting diode (LED) phototherapy on muscle deoxygenation and pulmonary oxygen uptake kinetics in patients with diabetes mellitus: study protocol for a randomized controlled trial.

PubMed

Francisco, Cristina de Oliveira; Beltrame, Thomas; Ferraresi, Cleber; Parizotto, Nivaldo Antonio; Bagnato, Vanderlei Salvador; Borghi Silva, Audrey; Benze, Benedito Galvão; Porta, Alberto; Catai, Aparecida Maria

2015-12-15

Type 2 diabetes mellitus (DM) is responsible for a significant reduction in the quality of life due to its negative impact on functional capacity. Cardiopulmonary fitness impairment in DM patients has been associated with limited tissue oxygenation. Phototherapy is widely utilized to treat several disorders due to expected light-tissue interaction. This type of therapy may help to improve muscular oxygenation, thereby increasing aerobic fitness and functional capacity. This study is a randomized, double-blind, placebo-controlled crossover trial approved by the Ethics Committee of the Federal University of São Carlos and registered at ClinicalTrials.gov. Four separate tests will be performed to evaluate the acute effect of phototherapy. All participants will receive both interventions in random order: light-emitting diode therapy (LEDT) and placebo, with a minimum 14-day interval between sessions (washout period). Immediately after the intervention, participants will perform moderate constant workload cycling exercise corresponding to 80 % of the pulmonary oxygen uptake [Formula: see text] during the gas exchange threshold (GET). LEDT will be administered with a multidiode cluster probe (50 GaAIA LEDs, 850 ηm, 75 mW each diode, and 3 J per point) before each exercise session. Pulmonary oxygen uptake, muscle oxygenation, heart rate, and arterial pressure will be measured using a computerized metabolic cart, a near-infrared spectrometer, an electrocardiogram, and a photoplethysmography system, respectively. The main objective of this study is to evaluate the acute effects of muscular pre-conditioning using LED phototherapy on pulmonary oxygen uptake, muscle oxygenation, heart rate, and arterial pressure dynamics during dynamic moderate exercise. We hypothesize that phototherapy may be beneficial to optimize aerobic fitness in the DM population. Data will be published after the study is completed. Registered at ClinicalTrials.gov under trial number NCT01889784 (date

Hyperspectral imaging for early detection of oxygenation and perfusion changes in irradiated skin

NASA Astrophysics Data System (ADS)

Chin, Michael S.; Freniere, Brian B.; Lo, Yuan-Chyuan; Saleeby, Jonathan H.; Baker, Stephen P.; Strom, Heather M.; Ignotz, Ronald A.; Lalikos, Janice F.; Fitzgerald, Thomas J.

2012-02-01

Studies examining acute oxygenation and perfusion changes in irradiated skin are limited. Hyperspectral imaging (HSI), a method of wide-field, diffuse reflectance spectroscopy, provides noninvasive, quantified measurements of cutaneous oxygenation and perfusion. This study examines whether HSI can assess acute changes in oxygenation and perfusion following irradiation. Skin on both flanks of nude mice (n=20) was exposed to 50 Gy of beta radiation from a strontium-90 source. Hyperspectral images were obtained before irradiation and on selected days for three weeks. Skin reaction assessment was performed concurrently with HSI. Desquamative injury formed in all irradiated areas. Skin reactions were first seen on day 7, with peak formation on day 14, and resolution beginning by day 21. HSI demonstrated increased tissue oxygenation on day 1 before cutaneous changes were observed (p<0.001). Further increases over baseline were seen on day 14, but returned to baseline levels by day 21. For perfusion, similar increases were seen on days 1 and 14. Unlike tissue oxygenation, perfusion was decreased below baseline on day 21 (p<0.002). HSI allows for complete visualization and quantification of tissue oxygenation and perfusion changes in irradiated skin, and may also allow prediction of acute skin reactions based on early changes seen after irradiation.

Transmission of arterial oxygen partial pressure oscillations to the cerebral microcirculation in a porcine model of acute lung injury caused by cyclic recruitment and derecruitment.

PubMed

Klein, K U; Boehme, S; Hartmann, E K; Szczyrba, M; Heylen, L; Liu, T; David, M; Werner, C; Markstaller, K; Engelhard, K

2013-02-01

Cyclic recruitment and derecruitment (R/D) play a key role in the pathomechanism of acute lung injury (ALI) leading to respiration-dependent oscillations of arterial partial pressure of oxygen (Pa(O(2))). These Pa(O(2)) oscillations could also be forwarded to the cerebral microcirculation. In 12 pigs, partial pressure of oxygen was measured in the thoracic aorta (Pa(O(2))) and subcortical cerebral tissue (Pbr(O(2))). Cerebral cortical haemoglobin oxygen saturation (Sbr(O(2))), cerebral blood flow (CBF), and peripheral haemoglobin saturation (Sp(O(2))) were assessed by spectroscopy and laser Doppler flowmetry. Measurements at different fractions of inspired oxygen (F(I(O(2)))) were performed at baseline and during cyclic R/D. frequency domain analysis, the Mann-Whitney test, linear models to test the influence of Pa(O(2)) and systolic arterial pressure (SAP) oscillations on cerebral measurements. Parameters [mean (SD)] remained stable during baseline. Pa(O(2)) oscillations [10.6 (8) kPa, phase(reference)], systemic arterial pressure (SAP) oscillations [20 (9) mm Hg, phase(Pa(O(2))-SAP) -33 (72)°], and Sp(O(2))oscillations [1.9 (1.7)%, phase(Pa(O(2))-Sp(O(2))) 264 (72)°] were detected during lung R/D at 1.0. Pa(O(2)) oscillations decreased [2.7 (3.5) kPa, P=0.0008] and Sp(O(2)) oscillations increased [6.8 (3.9)%, P=0.0014] at F(I(O(2))) 0.3. In the brain, synchronized Pbr(O(2)) oscillations [0.6 (0.4) kPa, phase(Pa(O(2))-Pbr(O(2))) 90 (39)°], Sbr(O(2)) oscillations [4.1 (1.5)%, phase(Pa(O(2))-Sbr(O(2))) 182 (54)°], and CBF oscillations [198 (176) AU, phase(Pa(O(2))-CBF) 201 (63)°] occurred that were dependent on Pa(O(2)) and SAP oscillations. Pa(O(2)) oscillations caused by cyclic R/D are transmitted to the cerebral microcirculation in a porcine model of ALI. These cyclic oxygen alterations could play a role in the crosstalk of acute lung and brain injury.

Conference on MTBE and Other Oxygenates

EPA Science Inventory

After reports of acute health symptoms (e.g., headache, nausea, eye irritation) arose following the introduction of oxygenated gasoline in Alaska and some other locales in late 1992, EPA, the Centers for Disease Control and Prevention, academic institutions, and other organizatio...

Oxygen uptake response to cycle ergometry in post-acute stroke patients with different severity of hemiparesis.

PubMed

Chen, Chun-Kai; Weng, Ming-Cheng; Chen, Tien-Wen; Huang, Mao-Hsiung

2013-11-01

This study evaluated the impact of severity of hemiparesis on oxygen uptake (VO2) response in post-acute stroke patients. Sixty-four patients with a mean poststroke interval of 8.6 ± 3.8 days underwent a ramp cardiopulmonary exercise test on a cycling ergometer to volitional termination. Mean peak VO2 (VO2peak) and work efficiency (ΔVO2/ΔWR) were measured by open-circuit spirometry during standard upright ergometer cycling. Severity of the hemiparetic lower limb was assessed by Brunnstrom's motor recovery stages lower extremity (BMRSL). VO2peak was 10% lower in hemiparetic leg with BMRSL V than in that with BMRSL VI, 20% lower in BMRSL IV, and 50% lower in BMRSL III. ΔVO2/ΔWR was higher for the group with increased BMRSL. The relations were consistent after adjustment for age, sex, body mass index, stroke type, hemiparetic side, modified Ashworth Scale, time poststroke, comorbidities, and medications. Our findings revealed that O2peak is dependent on the severity of hemiparesis in leg, and along with ΔO2/ΔWR closely related to the severity of hemiparesis in post-acute stroke patients, regardless of the types and locations of lesion after stroke, as well as the differences in comorbidities and medications. Copyright © 2013. Published by Elsevier B.V.

Interplay between O2 and SnO2: oxygen ionosorption and spectroscopic evidence for adsorbed oxygen.

PubMed

Gurlo, Alexander

2006-10-13

Tin dioxide is the most commonly used material in commercial gas sensors based on semiconducting metal oxides. Despite intensive efforts, the mechanism responsible for gas-sensing effects on SnO(2) is not fully understood. The key step is the understanding of the electronic response of SnO(2) in the presence of background oxygen. For a long time, oxygen interaction with SnO(2) has been treated within the framework of the "ionosorption theory". The adsorbed oxygen species have been regarded as free oxygen ions electrostatically stabilized on the surface (with no local chemical bond formation). A contradiction, however, arises when connecting this scenario to spectroscopic findings. Despite trying for a long time, there has not been any convincing spectroscopic evidence for "ionosorbed" oxygen species. Neither superoxide ions O(2)(-), nor charged atomic oxygen O,(-) nor peroxide ions O(2)(2-) have been observed on SnO(2) under the real working conditions of sensors. Moreover, several findings show that the superoxide ion does not undergo transformations into charged atomic oxygen at the surface, and represents a dead-end form of low-temperature oxygen adsorption on reduced metal oxide.

Method for determining the effects of oxygen plasma on a specimen

NASA Technical Reports Server (NTRS)

Whitaker, Ann F. (Inventor)

1991-01-01

A method for determining the effects of exposure of oxygen plasma on a specimen such as a thin film polymer or thin metals. The method includes providing an apparatus with a chamber having a holder supporting the polymer specimen in a plasma environment provided in the chamber. The chamber is regulated to a predetermined pressure and set temperature prior to the introduction of oxygen plasma therein. The specimen is then subjected to the plasma environment for a predetermined time during which time the temperature of the specimen is sensed and regulated to be maintained at the set temperature. Temperature sensing is accomplished by a probe which senses any changes in bulk sample temperature. Temperature regulation is provided by a thermoelectric module and by a coolant flow tube.

Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask

NASA Technical Reports Server (NTRS)

Kelly, Mark; Pettit, Donald

2003-01-01

A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.

Hyperbaric Oxygen Therapy Alleviates Carbon Monoxide Poisoning-Induced Delayed Memory Impairment by Preserving Brain-Derived Neurotrophic Factor-Dependent Hippocampal Neurogenesis.

PubMed

Liu, Wen-Chung; Yang, San-Nan; Wu, Chih-Wei J; Chen, Lee-Wei; Chan, Julie Y H

2016-01-01

To test the hypothesis that hyperbaric oxygen therapy ameliorates delayed cognitive impairment after acute carbon monoxide poisoning by promoting neurogenesis through upregulating the brain-derived neurotrophic factor in the hippocampus. Laboratory animal experiments. University/Medical center research laboratory. Adult, male Sprague-Dawley rats. Rats were divided into five groups: (1) non-carbon monoxide-treated control, (2) acute carbon monoxide poisoning, (3) acute carbon monoxide poisoning followed by 7-day hyperbaric oxygen treatment, (4) carbon monoxide + hyperbaric oxygen with additional intracerebroventricular infusion of Fc fragment of tyrosine kinase receptor B protein (TrkB-Fc) chimera, and (5) acute carbon monoxide poisoning followed by intracerebroventricular infusion of brain-derived neurotrophic factor. Acute carbon monoxide poisoning was achieved by exposing the rats to carbon monoxide at 2,500 ppm for 40 minutes, followed by 3,000 ppm for 20 minutes. Hyperbaric oxygen therapy (at 2.5 atmospheres absolute with 100% oxygen for 60 min) was conducted during the first 7 days after carbon monoxide poisoning. Recombinant human TrkB-Fc chimera or brain-derived neurotrophic factor was infused into the lateral ventricle via the implanted osmotic minipump. For labeling of mitotic cells in the hippocampus, bromodeoxyuridine was injected into the peritoneal cavity. Distribution of bromodeoxyuridine and two additional adult neurogenesis markers, Ki-67 and doublecortin, in the hippocampus was evaluated by immunohistochemistry or immunofluorescence staining. Tissue level of brain-derived neurotrophic factor was assessed by enzyme-linked immunosorbent assay. Cognitive behavior was evaluated by the use of eight-arm radial maze. Acute carbon monoxide poisoning significantly suppressed adult hippocampal neurogenesis evident by the reduction in number of bromodeoxyuridine-positive, Ki-67⁺, and doublecortin⁺ cells in the subgranular zone of the dentate gyrus. This

An Audit of Change in Clinical Practice: From Oxygen-Driven to Air-Driven Nebulisers for Prehospital Patients with Acute Exacerbations of Chronic Obstructive Pulmonary Disease (AECOPD).

PubMed

Heys, Deborah; Swain, Andrew; Knowles, Sarah; Waugh, Amy; Bailey, Mark

2017-11-29

In developed countries, ambulances normally carry oxygen cylinders but not compressed air. Treatment of acute exacerbations of COPD (AECOPD) with oxygen-driven nebulisers can result in hypercapnia and acidosis. Attempts to avoid this have involved interrupted administration of oxygen. 1 However, small battery-powered air nebulisers are now available. This study aims to compare the prehospital oxygen saturations and treatment of patients suffering from AECOPD before and after the introduction of air nebulisers. The oxygen saturations and treatment of 200 AECOPD patients before and 200 AECOPD patients after the introduction of air nebulisers were compared. Compliance with a target saturation of 88-92% was calculated. The median final oxygen saturation was lower for the post-intervention category (94%) than the pre-intervention category (96%). There was an increase in air nebuliser use from 0% to 56% (p < 0.001) and a decrease in oxygen use from 100% to 71.5% (p < 0.001). There was a numerical increase in the proportion of patients arriving at hospital with oxygen saturations of 88 - 92% following introduction of the air nebulisers (24% vs 16.5%) and a decrease in patients arriving with high saturations (67.5% vs 76.5%). The likelihood of achieving the target oxygen saturations following introduction of air nebulisers increased (odds ratio 1.598; 95% confidence interval 0.974, 2.621). The introduction of prehospital air nebulisers resulted in a reduction in oxygen therapy in patients with AECOPD and a lower median prehospital oxygen saturation. This study supports the use of air nebulisers in the prehospital setting. This article is protected by copyright. All rights reserved.

High flow nasal cannula oxygen versus noninvasive ventilation in adult acute respiratory failure: a systematic review of randomized-controlled trials.

PubMed

Beng Leong, Lim; Wei Ming, Ng; Wei Feng, Lee

2018-06-19

We reviewed the use of noninvasive ventilation (NIV) versus high flow nasal cannula (HFNC) oxygen in adult acute respiratory failure (ARF). We searched major databases and included randomized trials comparing at least NIV with HFNC or NIV+HFNC with NIV in ARF. Primary outcomes included intubation/re-intubation rates. Secondary outcomes were ICU mortality and morbidities. Five trials were included; three compared HFNC with NIV, one compared HFNC, NIV and oxygen whereas one compared HFNC+NIV with NIV. Patients had hypoxaemic ARF (PaO2/FiO2≤300 mmHg). Heterogeneity prevented result pooling. Three and two studies had superiority and noninferiority design, respectively. Patients were postcardiothoracic surgery, mixed medical/surgical patients and those with pneumonia. Two trials were conducted after extubation, two before intubation and one during intubation. Three trials reported intubation/re-intubation rates as the primary outcomes. The other two trials reported the lowest peripheral capillary oxygen saturation readings during bronchoscopy or intubation. In the former three trials, the odds ratio for intubation/re-intubation rates between HFNC versus the NIV group ranged from 0.80 (95% confidence interval: 0.54-1.19) to 1.65 (95% confidence interval: 0.96-2.84). In the latter two trials, only one reported a difference in the lowest peripheral capillary oxygen saturation between NIV+HFNC versus the NIV group during intubation [100% (interquartile range: 95-100) vs. 96% (interquartile range: 92-99); P=0.029]. The secondary outcomes included differences in ICU mortality and patient tolerability, favouring HFNC, were conflicting, but highlighted future research directions. These include patients with hypercapneic ARF, more severe hypoxaemia (PaO2/FiO2≤200 mmHg), a superiority design, an oxygen arm and patient-centred outcomes.

Testicular regulation of neuronal glucose and monocarboxylate transporter gene expression profiles in CNS metabolic sensing sites during acute and recurrent insulin-induced hypoglycemia.

PubMed

Vavaiya, Kamlesh V; Paranjape, Sachin A; Briski, Karen P

2007-01-01

Recurrent insulin-induced hypoglycemia (RIIH) impairs glucose counter-regulatory function in male humans and rodents and, in the latter, diminishes neuronal activation in CNS structures that monitor metabolic homeostasis, including the lateral hypothalamic area (LHA) and dorsal vagal complex (DVC). We investigated whether habituated neuronal reactivity in CNS sensing sites to hypoglycemia is correlated with modified monocarboxylate and/or glucose uptake by using quantitative real-time RT-PCR to analyze neuronal monocarboxylate transporter (MCT2) and glucose transporter variant (GLUT and GLUT4) gene expression profiles in the microdissected LHA, ventromedial nucleus hypothalamus (VMH), and DVC after one or multiple insulin injections. Because orchidectomy (ORDX) maintains uniform glycemic responses to RIIH in male rats, we also examined whether regional gene response patterns are testes dependent. In the intact male rat DVC, MCT2, GLUT3, and GLUT4 gene expression was not altered by acute hypoglycemia but was enhanced by RIIH. MCT2 and GLUT3 mRNA levels in the ORDX rat DVC did not differ among groups, but GLUT4 transcripts were progressively increased by acute and recurrent hypoglycemia. Precedent hypoglycemia decreased or increased basal MCT2 and GLUT4 gene expression, respectively, in the intact rat LHA; LHA GLUT3 transcription was augmented by RIIH in intact rats only. Acute hypoglycemia suppressed MCT2, GLUT3, and GLUT4 gene expression in the intact rat VMH, a response that was abolished by RIIH. In ORDX rats, VMH gene transcript levels were unchanged in response to one dose of insulin but were selectively diminished during RIIH. These data demonstrate site-specific, testes-dependent effects of acute and recurrent hypoglycemia on neuronal metabolic substrate transporter gene expression in characterized rat brain metabolic sensing loci and emphasize the need to assess the impact of potential alterations in glucose and lactate uptake during RIIH on general and

Effects of a human recombinant alkaline phosphatase on renal hemodynamics, oxygenation and inflammation in two models of acute kidney injury.

PubMed

Peters, Esther; Ergin, Bülent; Kandil, Asli; Gurel-Gurevin, Ebru; van Elsas, Andrea; Masereeuw, Rosalinde; Pickkers, Peter; Ince, Can

2016-12-15

Two small clinical trials indicated that administration of bovine intestinal alkaline phosphatase (AP) improves renal function in critically ill patients with sepsis-associated acute kidney injury (AKI), for which the mechanism of action is not completely understood. Here, we investigated the effects of a newly developed human recombinant AP (recAP) on renal oxygenation and hemodynamics and prevention of kidney damage and inflammation in two in vivo AKI models. To induce AKI, male Wistar rats (n=18) were subjected to renal ischemia (30min) and reperfusion (I/R), or sham-operated. In a second model, rats (n=18) received a 30min infusion of lipopolysaccharide (LPS; 2.5mg/kg), or saline, and fluid resuscitation. In both models, recAP (1000U/kg) was administered intravenously (15min before reperfusion, or 90min after LPS). Following recAP treatment, I/R-induced changes in renal blood flow, renal vascular resistance and oxygen delivery at early, and cortical microvascular oxygen tension at late reperfusion were no longer significantly affected. RecAP did not influence I/R-induced effects on mean arterial pressure. During endotoxemia, recAP treatment did not modulate the LPS-induced changes in systemic hemodynamics and renal oxygenation. In both models, recAP did exert a clear renal protective anti-inflammatory effect, demonstrated by attenuated immunostaining of inflammatory, tubular injury and pro-apoptosis markers. Whether this renal protective effect is sufficient to improve outcome of patients suffering from sepsis-associated AKI is being investigated in a large clinical trial. Copyright © 2016. Published by Elsevier Inc.

Renal Tubular Cell Mitochondrial Dysfunction Occurs Despite Preserved Renal Oxygen Delivery in Experimental Septic Acute Kidney Injury

PubMed Central

Pollen, Sean; Greco, Elisabetta; Courtneidge, Holly; Hall, Andrew M.; Duchen, Michael R.; Tam, Frederick W. K.; Unwin, Robert J.; Singer, Mervyn

2018-01-01

Objective: To explain the paradigm of significant renal functional impairment despite preserved hemodynamics and histology in sepsis-induced acute kidney injury. Design: Prospective observational animal study. Setting: University research laboratory. Subjects: Male Wistar rats. Intervention: Using a fluid-resuscitated sublethal rat model of fecal peritonitis, changes in renal function were characterized in relation to global and renal hemodynamics, and histology at 6 and 24 hours (n = 6–10). Sham-operated animals were used as comparison (n = 8). Tubular cell mitochondrial function was assessed using multiphoton confocal imaging of live kidney slices incubated in septic serum. Measurements and Main Results: By 24 hours, serum creatinine was significantly elevated with a concurrent decrease in renal lactate clearance in septic animals compared with sham-operated and 6-hour septic animals. Renal uncoupling protein-2 was elevated in septic animals at 24 hours although tubular cell injury was minimal and mitochondrial ultrastructure in renal proximal tubular cells preserved. There was no significant change in global or renal hemodynamics and oxygen delivery/consumption between sham-operated and septic animals at both 6- and 24-hour timepoints. In the live kidney slice model, mitochondrial dysfunction was seen in proximal tubular epithelial cells incubated with septic serum with increased production of reactive oxygen species, and decreases in nicotinamide adenine dinucleotide and mitochondrial membrane potential. These effects were prevented by coincubation with the reactive oxygen species scavenger, 4-hydroxy-2,2,6,6-tetramethyl-piperidin-1-oxyl. Conclusions: Renal dysfunction in sepsis occurs independently of hemodynamic instability or structural damage. Mitochondrial dysfunction mediated by circulating mediators that induce local oxidative stress may represent an important pathophysiologic mechanism. PMID:29293148

Mitochondria control acute and chronic responses to hypoxia.

PubMed

McElroy, G S; Chandel, N S

2017-07-15

There are numerous mechanisms by which mammals respond to hypoxia. These include acute changes in pulmonary arterial tone due to smooth muscle cell contraction, acute increases in respiration triggered by the carotid body chemosensory cells, and chronic changes such as induction of red blood cell proliferation and angiogenesis by hypoxia inducible factor targets erythropoietin and vascular endothelial growth factor, respectively. Mitochondria account for the majority of oxygen consumption in the cell and have recently been appreciated to serve as signaling organelles required for the initiation or propagation of numerous homeostatic mechanisms. Mitochondria can influence cell signaling by production of reactive oxygen species and metabolites. Here we review recent evidence that mitochondrial signals can imitate acute and chronic hypoxia responses. Copyright © 2017 Elsevier Inc. All rights reserved.

Oxygen-dependent quenching of phosphorescence used to characterize improved myocardial oxygenation resulting from vasculogenic cytokine therapy

PubMed Central

Hiesinger, William; Vinogradov, Sergei A.; Atluri, Pavan; Fitzpatrick, J. Raymond; Frederick, John R.; Levit, Rebecca D.; McCormick, Ryan C.; Muenzer, Jeffrey R.; Yang, Elaine C.; Marotta, Nicole A.; MacArthur, John W.; Wilson, David F.

2011-01-01

This study evaluates a therapy for infarct modulation and acute myocardial rescue and utilizes a novel technique to measure local myocardial oxygenation in vivo. Bone marrow-derived endothelial progenitor cells (EPCs) were targeted to the heart with peri-infarct intramyocardial injection of the potent EPC chemokine stromal cell-derived factor 1α (SDF). Myocardial oxygen pressure was assessed using a noninvasive, real-time optical technique for measuring oxygen pressures within microvasculature based on the oxygen-dependent quenching of the phosphorescence of Oxyphor G3. Myocardial infarction was induced in male Wistar rats (n = 15) through left anterior descending coronary artery ligation. At the time of infarction, animals were randomized into two groups: saline control (n = 8) and treatment with SDF (n = 7). After 48 h, the animals underwent repeat thoracotomy and 20 μl of the phosphor Oxyphor G3 was injected into three areas (peri-infarct myocardium, myocardial scar, and remote left hindlimb muscle). Measurements of the oxygen distribution within the tissue were then made in vivo by applying the end of a light guide to the beating heart. Compared with controls, animals in the SDF group exhibited a significantly decreased percentage of hypoxic (defined as oxygen pressure ≤ 15.0 Torr) peri-infarct myocardium (9.7 ± 6.7% vs. 21.8 ± 11.9%, P = 0.017). The peak oxygen pressures in the peri-infarct region of the animals in the SDF group were significantly higher than the saline controls (39.5 ± 36.7 vs. 9.2 ± 8.6 Torr, P = 0.02). This strategy for targeting EPCs to vulnerable peri-infarct myocardium via the potent chemokine SDF-1α significantly decreased the degree of hypoxia in peri-infarct myocardium as measured in vivo by phosphorescence quenching. This effect could potentially mitigate the vicious cycle of myocyte death, myocardial fibrosis, progressive ventricular dilatation, and eventual heart failure seen after acute myocardial infarction. PMID

Somatic Pairing of Chromosome 19 in Renal Oncocytoma Is Associated with Deregulated ELGN2-Mediated Oxygen-Sensing Response

PubMed Central

Petillo, David; Westphal, Michael; Koelzer, Katherine; Metcalf, Julie L.; Zhang, Zhongfa; Matsuda, Daisuke; Dykema, Karl J.; Houseman, Heather L.; Kort, Eric J.; Furge, Laura L.; Kahnoski, Richard J.; Richard, Stéphane; Vieillefond, Annick; Swiatek, Pamela J.; Teh, Bin Tean; Ohh, Michael; Furge, Kyle A.

2008-01-01

Chromosomal abnormalities, such as structural and numerical abnormalities, are a common occurrence in cancer. The close association of homologous chromosomes during interphase, a phenomenon termed somatic chromosome pairing, has been observed in cancerous cells, but the functional consequences of somatic pairing have not been established. Gene expression profiling studies revealed that somatic pairing of chromosome 19 is a recurrent chromosomal abnormality in renal oncocytoma, a neoplasia of the adult kidney. Somatic pairing was associated with significant disruption of gene expression within the paired regions and resulted in the deregulation of the prolyl-hydroxylase ELGN2, a key protein that regulates the oxygen-dependent degradation of hypoxia-inducible factor (HIF). Overexpression of ELGN2 in renal oncocytoma increased ubiquitin-mediated destruction of HIF and concomitantly suppressed the expression of several HIF-target genes, including the pro-death BNIP3L gene. The transcriptional changes that are associated with somatic pairing of chromosome 19 mimic the transcriptional changes that occur following DNA amplification. Therefore, in addition to numerical and structural chromosomal abnormalities, alterations in chromosomal spatial dynamics should be considered as genomic events that are associated with tumorigenesis. The identification of EGLN2 as a significantly deregulated gene that maps within the paired chromosome region directly implicates defects in the oxygen-sensing network to the biology of renal oncocytoma. PMID:18773095

Does high-flow nasal cannula oxygen improve outcome in acute hypoxemic respiratory failure? A systematic review and meta-analysis.

PubMed

Lin, Si-Ming; Liu, Kai-Xiong; Lin, Zhi-Hong; Lin, Pei-Hong

2017-10-01

To evaluate the efficacy of high-flow nasal cannula (HFNC) in the rate of intubation and mortality for patients with acute hypoxemic respiratory failure. We searched Pubmed, EMBASE, and the Cochrane Library for relevant studies. Two reviewers extracted data and reviewed the quality of the studies independently. The primary outcome was the rate of intubation; secondary outcome was mortality in the hospital. Study-level data were pooled using a random-effects model when I2 was >50% or a fixed-effects model when I2 was <50%. Eight randomized controlled studies with a total of 1,818patients were considered. Pooled analysis showed that no statistically significant difference was found between groups regarding the rate of intubation (odds ratio [OR] = 0.79; 95% confidence interval [CI]: 0.60-1.04; P = 0.09; I2 = 36%) and no statistically significant difference was found between groups regarding hospital mortality (OR = 0.89; 95% CI: 0.62-127; P = 0.51; I2 = 47%). The use of HFNC showed a trend toward reduction in the intubation rate, which did not meet statistical significance, in patients with acute respiratory failure compared with conventional oxygen therapy (COT) and noninvasive ventilation (NIV). Moreover no difference in mortality. So, Large, well-designed, randomized, multi-center trials are needed to confirm the effects of HFNC in acute hypoxemic respiratory failure patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

New Optical Sensing Materials for Application in Marine Research

NASA Astrophysics Data System (ADS)

Borisov, S.; Klimant, I.

2012-04-01

Optical chemosensors are versatile analytical tools which find application in numerous fields of science and technology. They proved to be a promising alternative to electrochemical methods and are applied increasingly often in marine research. However, not all state-of-the- art optical chemosensors are suitable for these demanding applications since they do not fully fulfil the requirements of high luminescence brightness, high chemical- and photochemical stability or their spectral properties are not adequate. Therefore, development of new advanced sensing materials is still of utmost importance. Here we present a set of novel optical sensing materials recently developed in the Institute of Analytical Chemistry and Food Chemistry which are optimized for marine applications. Particularly, we present new NIR indicators and sensors for oxygen and pH which feature high brightness and low level of autofluorescence. The oxygen sensors rely on highly photostable metal complexes of benzoporphyrins and azabenzoporphyrins and enable several important applications such as simultaneous monitoring of oxygen and chlorophyll or ultra-fast oxygen monitoring (Eddy correlation). We also developed ulta-sensitive oxygen optodes which enable monitoring in nM range and are primary designed for investigation of oxygen minimum zones. The dynamic range of our new NIR pH indicators based on aza-BODIPY dyes is optimized for the marine environment. A highly sensitive NIR luminescent phosphor (chromium(III) doped yttrium aluminium borate) can be used for non-invasive temperature measurements. Notably, the oxygen, pH sensors and temperature sensors are fully compatible with the commercially available fiber-optic readers (Firesting from PyroScience). An optical CO2 sensor for marine applications employs novel diketopyrrolopyrrol indicators and enables ratiometric imaging using a CCD camera. Oxygen, pH and temperature sensors suitable for lifetime and ratiometric imaging of analytes

Pediatric acute respiratory distress syndrome: definition, incidence, and epidemiology: proceedings from the Pediatric Acute Lung Injury Consensus Conference.

PubMed

Khemani, Robinder G; Smith, Lincoln S; Zimmerman, Jerry J; Erickson, Simon

2015-06-01

Although there are similarities in the pathophysiology of acute respiratory distress syndrome in adults and children, pediatric-specific practice patterns, comorbidities, and differences in outcome necessitate a pediatric-specific definition. We sought to create such a definition. A subgroup of pediatric acute respiratory distress syndrome investigators who drafted a pediatric-specific definition of acute respiratory distress syndrome based on consensus opinion and supported by detailed literature review tested elements of the definition with patient data from previously published investigations. International PICUs. Children enrolled in published investigations of pediatric acute respiratory distress syndrome. None. Several aspects of the proposed pediatric acute respiratory distress syndrome definition align with the Berlin Definition of acute respiratory distress syndrome in adults: timing of acute respiratory distress syndrome after a known risk factor, the potential for acute respiratory distress syndrome to coexist with left ventricular dysfunction, and the importance of identifying a group of patients at risk to develop acute respiratory distress syndrome. There are insufficient data to support any specific age for "adult" acute respiratory distress syndrome compared with "pediatric" acute respiratory distress syndrome. However, children with perinatal-related respiratory failure should be excluded from the definition of pediatric acute respiratory distress syndrome. Larger departures from the Berlin Definition surround 1) simplification of chest imaging criteria to eliminate bilateral infiltrates; 2) use of pulse oximetry-based criteria when PaO2 is unavailable; 3) inclusion of oxygenation index and oxygen saturation index instead of PaO2/FIO2 ratio with a minimum positive end-expiratory pressure level for invasively ventilated patients; 4) and specific inclusion of children with preexisting chronic lung disease or cyanotic congenital heart disease. This

Relationship of oxygen dose to angiogenesis induction in irradiated tissue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marx, R.E.; Ehler, W.J.; Tayapongsak, P.

1990-11-01

This study was accomplished in an irradiated rabbit model to assess the angiogenic properties of normobaric oxygen and hyperbaric oxygen as compared with air-breathing controls. Results indicated that normobaric oxygen had no angiogenic properties above normal revascularization of irradiated tissue than did air-breathing controls (p = 0.89). Hyperbaric oxygen demonstrated an eight- to ninefold increased vascular density over both normobaric oxygen and air-breathing controls (p = 0.001). Irradiated tissue develops a hypovascular-hypocellular-hypoxic tissue that does not revascularize spontaneously. Results failed to demonstrate an angiogenic effect of normobaric oxygen. It is suggested that oxygen in this sense is a drug requiringmore » hyperbaric pressures to generate therapeutic effects on chronically hypovascular irradiated tissue.« less

Singlet Oxygen-Induced Membrane Disruption and Serpin-Protease Balance in Vacuolar-Driven Cell Death.

PubMed

Koh, Eugene; Carmieli, Raanan; Mor, Avishai; Fluhr, Robert

2016-07-01

Singlet oxygen plays a role in cellular stress either by providing direct toxicity or through signaling to initiate death programs. It was therefore of interest to examine cell death, as occurs in Arabidopsis, due to differentially localized singlet oxygen photosensitizers. The photosensitizers rose bengal (RB) and acridine orange (AO) were localized to the plasmalemma and vacuole, respectively. Their photoactivation led to cell death as measured by ion leakage. Cell death could be inhibited by the singlet oxygen scavenger histidine in treatments with AO but not with RB In the case of AO treatment, the vacuolar membrane was observed to disintegrate. Concomitantly, a complex was formed between a vacuolar cell-death protease, RESPONSIVE TO DESSICATION-21 and its cognate cytoplasmic protease inhibitor ATSERPIN1. In the case of RB treatment, the tonoplast remained intact and no complex was formed. Over-expression of AtSerpin1 repressed cell death, only under AO photodynamic treatment. Interestingly, acute water stress showed accumulation of singlet oxygen as determined by fluorescence of Singlet Oxygen Sensor Green, by electron paramagnetic resonance spectroscopy and the induction of singlet oxygen marker genes. Cell death by acute water stress was inhibited by the singlet oxygen scavenger histidine and was accompanied by vacuolar collapse and the appearance of serpin-protease complex. Over-expression of AtSerpin1 also attenuated cell death under this mode of cell stress. Thus, acute water stress damage shows parallels to vacuole-mediated cell death where the generation of singlet oxygen may play a role. © 2016 American Society of Plant Biologists. All Rights Reserved.

A New Optical Oxygen Sensor Reveals Spatial and Temporal Variations of Dissolved Oxygen at Ecohydrological Interfaces

NASA Astrophysics Data System (ADS)

Brandt, T.; Schmidt, C.; Fleckenstein, J. H.; Vieweg, M.; Harjung, A.

2015-12-01

The spatial and temporal distribution of dissolved oxygen (DO) at highly reactive aquatic interfaces, e.g. in the hyporheic zone (HZ), is a primary indicator of redox and interlinked biogeochemical zonations. However, continuous measuring of DO over time and depths is challenging due to the dynamic and potentially heterogenic nature of the HZ. We further developed a novel technology for spatially continuous in situ vertical oxygen profiling based on optical sensing (Vieweg et al, 2013). Continuous vertical measurements to a depth of 50 cm are obtained by the motor-controlled insertion of a side-firing Polymer Optical Fiber (POF) into tubular DO probes. Our technology allows minimally invasive DO measurements without DO consumption at high spatial resolution in the mm range. The reduced size of the tubular probe (diameter 5 mm) substantially minimizes disturbance of flow conditions. We tested our technology in situ in the HZ of an intermittent stream during the drying period. Repeated DO measurements were taken over a total duration of six weeks at two locations up- and downstream of a pool-cascade sequence. We were able to precisely map the spatial DO distribution which exhibited sharp gradients and rapid temporal changes as a function of changing hydrologic conditions. Our new vertical oxygen sensing technology will help to provide new insights to the coupling of transport of DO and biogeochemical reactions at aquatic interfaces. Vieweg, M., Trauth, N., Fleckenstein, J. H., Schmidt, C. (2013): Robust Optode-Based Method for Measuring in Situ Oxygen Profiles in Gravelly Streambeds. Environmental Science & Technology. doi:10.1021/es401040w

Acquired factor V inhibitor in a patient receiving venous-venous extracorporeal membrane oxygenation for Legionella pneumonia.

PubMed

Leung, Anne K H; Ng, George W Y; Sin, K C; Au, S Y; Lai, K Y; Lee, K L; Law, K I

2015-04-01

We report a rare complication of factor V deficiency in a patient having Legionella pneumonia. This patient also had other complications like severe acute respiratory distress syndrome, acute kidney injury, and septic shock that required venous-venous extracorporeal membrane oxygenation support. This is the first reported case of acquired factor V deficiency in a patient receiving extracorporeal membrane oxygenation for Legionella pneumonia. With the combined use of intravenous immunoglobulin, rituximab and plasma exchange, we achieved rapid clearance of the factor V inhibitor within 1 week so as to allow safe decannulation of extracorporeal membrane oxygenation.

Oxygenation impairment after total arch replacement with a stented elephant trunk for type-A dissection.

PubMed

Shen, Yuwen; Liu, Chuanzhen; Fang, Changcun; Xi, Jie; Wu, Shuming; Pang, Xinyan; Song, Guangmin

2018-06-01

To study the risk factors of oxygenation impairment in patients with type-A acute aortic dissection who underwent total arch replacement with a stented elephant trunk. In this study, 169 consecutive patients were enrolled who were diagnosed with type-A acute aortic dissection and underwent a total arch replacement procedure at the Qilu Hospital of Shandong University between January 2015 and February 2017. Postoperative oxygenation impairment was defined as arterial oxygen partial pressure/inspired oxygen fraction ≤ 200 with positive end expiratory pressure ≥ 5 cm H 2 O that occurred within 72 hours of surgery. Perioperative clinical characteristics of all patients were collected and univariable analyses were performed. Risk factors associated with oxygenation impairment identified by univariable analyses were included in the multivariable regression analysis. The incidence of postoperative oxygenation impairment was 48.5%. Postoperative oxygenation impairment was associated with prolonged mechanical ventilation time, intensive care unit stay, and hospital stay. Multivariable regression analysis demonstrated that body mass index (odds ratio [OR], 1.204; 95% confidence interval [CI], 1.065-1.361; P = .003), preoperative oxygenation impairment (OR, 9.768; 95% CI, 4.159-22.941; P < .001), preoperative homocysteine (OR, 1.080; 95% CI, 1.006-1.158; P = .032), circulatory arrest time (OR, 1.123; 95% CI, 1.044-1.207; P = .002), and plasma transfusion (OR, 1.002; 95% CI, 1.001-1.003; P = .002) were significantly associated with postoperative oxygenation impairment. Postoperative oxygenation impairment is a common complication of surgery for type-A acute aortic dissection. Body mass index, preoperative oxygenation impairment, preoperative homocysteine, circulatory arrest time, and plasma transfusion were independent risk factors for oxygenation impairment after a total arch replacement procedure. Copyright © 2018 The American Association for Thoracic

A novel microbial fuel cell sensor with biocathode sensing element.

PubMed

Jiang, Yong; Liang, Peng; Liu, Panpan; Wang, Donglin; Miao, Bo; Huang, Xia

2017-08-15

The traditional microbial fuel cell (MFC) sensor with bioanode as sensing element delivers limited sensitivity to toxicity monitoring, restricted application to only anaerobic and organic rich water body, and increased potential fault warning to the combined shock of organic matter/toxicity. In this study, the biocathode for oxygen reduction reaction was employed for the first time as the sensing element in MFC sensor for toxicity monitoring. The results shown that the sensitivity of MFC sensor with biocathode sensing element (7.4±2.0 to 67.5±4.0mA% -1 cm -2 ) was much greater than that showed by bioanode sensing element (3.4±1.5 to 5.5±0.7mA% -1 cm -2 ). The biocathode sensing element achieved the lowest detection limit reported to date using MFC sensor for formaldehyde detection (0.0005%), while the bioanode was more applicable for higher concentration (>0.0025%). There was a quicker response of biocathode sensing element with the increase of conductivity and dissolved oxygen (DO). The biocathode sensing element made the MFC sensor directly applied to clean water body monitoring, e.g., drinking water and reclaimed water, without the amending of background organic matter, and it also decreased the warning failure when challenged by a combined shock of organic matter/toxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

Role of distal arginine in early sensing intermediates in the heme domain of the oxygen sensor FixL.

PubMed

Jasaitis, Audrius; Hola, Klara; Bouzhir-Sima, Latifa; Lambry, Jean-Christophe; Balland, Veronique; Vos, Marten H; Liebl, Ursula

2006-05-16

FixL is a bacterial heme-based oxygen sensor, in which release of oxygen from the sensing PAS domain leads to activation of an associated kinase domain. Static structural studies have suggested an important role of the conserved residue arginine 220 in signal transmission at the level of the heme domain. To assess the role of this residue in the dynamics and properties of the initial intermediates in ligand release, we have investigated the effects of R220X (X = I, Q, E, H, or A) mutations in the FixLH heme domain on the dynamics and spectral properties of the heme upon photolysis of O(2), NO, and CO using femtosecond transient absorption spectroscopy. Comparison of transient spectra for CO and NO dissociation with steady-state spectra indicated less strain on the heme in the ligand dissociation species for all mutants compared to the wild type (WT). For CO and NO, the kinetics were similar to those of the wild type, with the exception of (1) a relatively low yield of picosecond NO rebinding to R220A, presumably related to the increase in the free volume of the heme pocket, and (2) substantial pH-dependent picosecond to nanosecond rebinding of CO to R220H, related to formation of a hydrogen bond between CO and histidine 220. Upon excitation of the complex bound with the physiological sensor ligand O(2), a 5-8 ps decay phase and a nondecaying (>4 ns) phase were observed for WT and all mutants. The strong distortion of the spectrum associated with the decay phase in WT is substantially diminished in all mutant proteins, indicating an R220-induced role of the heme in the primary intermediate in signal transmission. Furthermore, the yield of dissociated oxygen after this phase ( approximately 10% in WT) is increased in all mutants, up to almost unity in R220A, indicating a key role of R220 in caging the oxygen near the heme through hydrogen bonding. Molecular dynamics simulations corroborate these findings and suggest motions of O(2) and arginine 220 away from the heme

Amphiphilic Fluorinated Polymer Nanoparticle Film Formation and Dissolved Oxygen Sensing Application

NASA Astrophysics Data System (ADS)

Gao, Yu; Zhu, Huie; Yamamoto, Shunsuke; Miyashita, Tokuji; Mitsuishi, Masaya

2016-04-01

Fluorinated polymer nanoparticle films were prepared by dissolving amphiphilic fluorinated polymer, poly (N-1H, 1H-pentadecafluorooctylmethacrylamide) (pC7F15MAA) in two miscible solvents (AK-225 and acetic acid). A superhydrophobic and porous film was obtained by dropcasting the solution on substrates. With higher ratios of AK-225 to acetic acid, pC7F15MAA was densified around acetic acid droplets, leading to the formation of pC7F15MAA nanoparticles. The condition of the nanoparticle film preparation was investigated by varying the mixing ratio or total concentration. A highly sensitive dissolved oxygen sensor system was successfully prepared utilizing a smart surface of superhydrophobic and porous pC7F15MAA nanoparticle film. The sensitivity showed I0/I40 = 126 in the range of dissolved oxygen concentration of 0 ~ 40 mg L-1. The oxygen sensitivity was compared with that of previous reports.

An oxygen pressure sensor using surface acoustic wave devices

NASA Technical Reports Server (NTRS)

Leighty, Bradley D.; Upchurch, Billy T.; Oglesby, Donald M.

1993-01-01

Surface acoustic wave (SAW) piezoelectric devices are finding widespread applications in many arenas, particularly in the area of chemical sensing. We have developed an oxygen pressure sensor based on coating a SAW device with an oxygen binding agent which can be tailored to provide variable sensitivity. The coating is prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer which is then sprayed onto the surface of the SAW device. Experimental data shows the feasibility of tailoring sensors to measure the partial pressure of oxygen from 2.6 to 67 KPa (20 to 500 torr). Potential applications of this technology are discussed.

Microbial Degradation of Fuel Oxygenates under Aerobic Conditions

DTIC Science & Technology

2007-03-01

for less hazardous oxygenate alternatives. One of the many factors that will contribute to selection of a new oxygenate will be its susceptibility to...tetra ethyl lead to gasoline as an octane booster was effective, but had significant drawbacks. The acute hazards of airborne lead were readily apparent...more of an inhalation hazard , causing irritation of the eyes, nose and throat. These compounds may also cause changes in the liver and kidneys

Ventilatory responses to acute and chronic hypoxia are altered in female but not male Paskin-deficient mice.

PubMed

Soliz, Jorge; Soulage, Christophe; Borter, Emanuela; van Patot, Martha Tissot; Gassmann, Max

2008-08-01

Proteins harboring a Per-Arnt-Sim (PAS) domain are versatile and allow archaea, bacteria, and plants to sense oxygen partial pressure, as well as light intensity and redox potential. A PAS domain associated with a histidine kinase domain is found in FixL, the oxygen sensor molecule of Rhizobium species. PASKIN is the mammalian homolog of FixL, but its function is far from being understood. Using whole body plethysmography, we evaluated the ventilatory response to acute and chronic hypoxia of homozygous deficient male and female PASKIN mice (Paskin-/-). Although only slight ventilatory differences were found in males, female Paskin-/- mice increased ventilatory response to acute hypoxia. Unexpectedly, females had an impaired ability to reach ventilatory acclimatization in response to chronic hypoxia. Central control of ventilation occurs in the brain stem respiratory centers and is modulated by catecholamines via tyrosine hydroxylase (TH) activity. We observed that TH activity was altered in male and female Paskin-/- mice. Peripheral chemoreceptor effects on ventilation were evaluated by exposing animals to hyperoxia (Dejours test) and domperidone, a peripheral ventilatory stimulant drug directly affecting the carotid sinus nerve discharge. Male and female Paskin-/- had normal peripheral chemosensory (carotid bodies) responses. In summary, our observations suggest that PASKIN is involved in the central control of hypoxic ventilation, modulating ventilation in a gender-dependent manner.

The effect of multidisciplinary extracorporeal membrane oxygenation team on clinical outcomes in patients with severe acute respiratory failure.

PubMed

Na, Soo Jin; Chung, Chi Ryang; Choi, Hee Jung; Cho, Yang Hyun; Sung, Kiick; Yang, Jeong Hoon; Suh, Gee Young; Jeon, Kyeongman

2018-02-27

The Extracorporeal Life Support Organization (ELSO) has suggested that extracorporeal membrane oxygenation (ECMO) patients should be managed by a multidisciplinary team. However, there are limited data on the impact of ECMO team on the outcomes of patients with severe acute respiratory failure. All consecutive patients with severe acute respiratory failure who underwent ECMO for respiratory support from January 2012 through December 2016 were divided into the pre-ECMO team period (before January 2014, n = 70) and the post-ECMO team period (after January 2014, n = 46). Clinical characteristics and outcomes were compared between the two groups. The mortality rates in the intensive care unit (72.9 vs. 50.0%, P = 0.012) and hospital (75.7 vs. 52.2%, P = 0.009) were significantly decreased in the post-ECMO team period compared to the pre-ECMO team period. The median duration of ECMO support was not different between the two periods. However, the proportion of patients successfully weaned off ECMO was higher in the post-ECMO team period (42.9 vs. 65.2%, P = 0.018). During ECMO support, the incidence of cannula problems (32.9 vs. 15.2%, P = 0.034) and cardiovascular events (88.6 vs. 65.2%, P = 0.002) was reduced after implementation of the ECMO team. The 1-year mortality was significantly different between the pre-ECMO team and post-ECMO team periods (37.8 vs. 14.3%, P = 0.005). After implementing a multidisciplinary ECMO team, survival rate in patients treated with ECMO for severe acute respiratory failure was significantly improved.

Oxygen-Inducible Glutamate Oxaloacetate Transaminase as Protective Switch Transforming Neurotoxic Glutamate to Metabolic Fuel During Acute Ischemic Stroke

PubMed Central

Rink, Cameron; Gnyawali, Surya; Peterson, Laura

2011-01-01

Abstract This work rests on our previous report (J Cereb Blood Flow Metab 30: 1275–1287, 2010) recognizing that glutamate (Glu) oxaloacetate transaminase (GOT) is induced when brain tissue hypoxia is corrected during acute ischemic stroke (AIS). GOT can metabolize Glu into tricarboxylic acid cycle intermediates and may therefore be useful to harness excess neurotoxic extracellular Glu during AIS as a metabolic substrate. We report that in cultured neural cells challenged with hypoglycemia, extracellular Glu can support cell survival as long as there is sufficient oxygenation. This effect is abrogated by GOT knockdown. In a rodent model of AIS, supplemental oxygen (100% O2 inhaled) during ischemia significantly increased GOT expression and activity in the stroke-affected brain tissue and prevented loss of ATP. Biochemical analyses and in vivo magnetic resonance spectroscopy during stroke demonstrated that such elevated GOT decreased Glu levels at the stroke-affected site. In vivo lentiviral gene delivery of GOT minimized lesion volume, whereas GOT knockdown worsened stroke outcomes. Thus, brain tissue GOT emerges as a novel target in managing stroke outcomes. This work demonstrates that correction of hypoxia during AIS can help clear extracellular neurotoxic Glu by enabling utilization of this amino acid as a metabolic fuel to support survival of the hypoglycemic brain tissue. Strategies to mitigate extracellular Glu-mediated neurodegeneration via blocking receptor-mediated excitotoxicity have failed in clinical trials. We introduce the concept that under hypoglycemic conditions extracellular Glu can be transformed from a neurotoxin to a survival factor by GOT, provided there is sufficient oxygen to sustain cellular respiration. Antioxid. Redox Signal. 14, 1777–1785. PMID:21361730

Measuring the viscosity of whole bovine lens using a fiber optic oxygen sensing system

PubMed Central

Thao, Mai T.; Perez, Daniel; Dillon, James

2014-01-01

Purpose To obtain a better understanding of oxygen and nutrient transport within the lens, the viscosity of whole lenses was investigated using a fiber optic oxygen sensor (optode). The diffusion coefficient of oxygen was calculated using the Stokes-Einstein equation at the slip boundary condition. Methods The optode was used to measure the oxygen decay signal in samples consisting of different glycerol/water solutions with known viscosities. The oxygen decay signal was fitted to a double exponential decay rate equation, and the lifetimes (tau) were calculated. It was determined that the tau-viscosity relationship is linear, which served as the standard curve. The same procedure was applied to fresh bovine lenses, and the unknown viscosity of the bovine lens was calculated from the tau-viscosity relationship. Results The average viscosity in a whole bovine lens was determined to be 5.74±0.88 cP by our method. Using the Stokes-Einstein equation at the slip boundary condition, the diffusion coefficient for oxygen was calculated to be 8.2 × 10−6 cm2/s. Conclusions These data indicate a higher resistance to flow for oxygen and nutrients in the lens than what is currently assumed in the literature. Overall, this study allows a better understanding of oxygen transport within the lens. PMID:24505211

Carbon Dioxide Fluctuations Are Associated with Changes in Cerebral Oxygenation and Electrical Activity in Infants Born Preterm.

PubMed

Dix, Laura Marie Louise; Weeke, Lauren Carleen; de Vries, Linda Simone; Groenendaal, Floris; Baerts, Willem; van Bel, Frank; Lemmers, Petra Maria Anna

2017-08-01

To evaluate the effects of acute arterial carbon dioxide partial pressure changes on cerebral oxygenation and electrical activity in infants born preterm. This retrospective observational study included ventilated infants born preterm with acute fluctuations of continuous end-tidal CO 2 (etCO 2 ) as a surrogate marker for arterial carbon dioxide partial pressure, during the first 72 hours of life. Regional cerebral oxygen saturation and fractional tissue oxygen extraction were monitored with near-infrared spectroscopy. Brain activity was monitored with 2-channel electroencephalography. Spontaneous activity transients (SATs) rate (SATs/minute) and interval between SATs (in seconds) were calculated. Ten-minute periods were selected for analysis: before, during, and after etCO 2 fluctuations of ≥5  mm Hg. Thirty-eight patients (mean ± SD gestational age of 29 ± 1.8 weeks) were included, with 60 episodes of etCO 2 increase and 70 episodes of etCO 2 decrease. During etCO 2 increases, brain oxygenation increased (regional cerebral oxygen saturation increased, fractional tissue oxygen extraction decreased; P < .01) and electrical activity decreased (SATs/minute decreased, interval between SATs increased; P < .01). All measures recovered when etCO 2 returned to baseline. During etCO 2 decreases, brain oxygenation decreased (regional cerebral oxygen saturation decreased, fractional tissue oxygen extraction decreased; P < .01) and brain activity increased (SATs/minute increased, P < .05), also with recovery after return of etCO 2 to baseline. An acute increase in etCO 2 is associated with increased cerebral oxygenation and decreased brain activity, whereas an acute decrease is associated with decreased cerebral oxygenation and slightly increased brain activity. Combining continuous CO 2 monitoring with near-infrared spectroscopy may enable the detection of otherwise undetected fluctuations in arterial carbon dioxide partial pressure that may be

Quantifying oxygen in paper-based cell cultures with luminescent thin film sensors.

PubMed

Boyce, Matthew W; Kenney, Rachael M; Truong, Andrew S; Lockett, Matthew R

2016-04-01

Paper-based scaffolds are an attractive material for generating 3D tissue-like cultures because paper is readily available and does not require specialized equipment to pattern, cut, or use. By controlling the exchange of fresh culture medium with the paper-based scaffolds, we can engineer diffusion-dominated environments similar to those found in spheroids or solid tumors. Oxygen tension directly regulates cellular phenotype and invasiveness through hypoxia-inducible transcription factors and also has chemotactic properties. To date, gradients of oxygen generated in the paper-based cultures have relied on cellular response-based readouts. In this work, we prepared a luminescent thin film capable of quantifying oxygen tensions in apposed cell-containing paper-based scaffolds. The oxygen sensors, which are polystyrene films containing a Pd(II) tetrakis(pentafluorophenyl)porphyrin dye, are photostable, stable in culture conditions, and not cytotoxic. They have a linear response for oxygen tensions ranging from 0 to 160 mmHg O2, and a Stern-Volmer constant (K sv) of 0.239 ± 0.003 mmHg O2 (-1). We used these oxygen-sensing films to measure the spatial and temporal changes in oxygen tension for paper-based cultures containing a breast cancer line that was engineered to constitutively express a fluorescent protein. By acquiring images of the oxygen-sensing film and the fluorescently labeled cells, we were able to approximate the oxygen consumption rates of the cells in our cultures.

Oxygen Administration Improves Survival but Worsens Cardiopulmonary Functions in Chlorine-exposed Rats.

PubMed

Okponyia, Obiefuna C; McGraw, Matthew D; Dysart, Marilyn M; Garlick, Rhonda B; Rioux, Jacqueline S; Murphy, Angela L; Roe, Gates B; White, Carl W; Veress, Livia A

2018-01-01

Chlorine is a highly reactive gas that can cause significant injury when inhaled. Unfortunately, its use as a chemical weapon has increased in recent years. Massive chlorine inhalation can cause death within 4 hours of exposure. Survivors usually require hospitalization after massive exposure. No countermeasures are available for massive chlorine exposure and supportive-care measures lack controlled trials. In this work, adult rats were exposed to chlorine gas (LD 58-67 ) in a whole-body exposure chamber, and given oxygen (0.8 Fi O 2 ) or air (0.21 Fi O 2 ) for 6 hours after baseline measurements were obtained. Oxygen saturation, vital signs, respiratory distress and neuromuscular scores, arterial blood gases, and hemodynamic measurements were obtained hourly. Massive chlorine inhalation caused severe acute respiratory failure, hypoxemia, decreased cardiac output, neuromuscular abnormalities (ataxia and hypotonia), and seizures resulting in early death. Oxygen improved survival to 6 hours (87% versus 42%) and prevented observed seizure-related deaths. However, oxygen administration worsened the severity of acute respiratory failure in chlorine-exposed rats compared with controls, with increased respiratory acidosis (pH 6.91 ± 0.04 versus 7.06 ± 0.01 at 2 h) and increased hypercapnia (180.0 ± 19.8 versus 103.2 ± 3.9 mm Hg at 2 h). In addition, oxygen did not improve neuromuscular abnormalities, cardiac output, or respiratory distress associated with chlorine exposure. Massive chlorine inhalation causes severe acute respiratory failure and multiorgan damage. Oxygen administration can improve short-term survival but appears to worsen respiratory failure, with no improvement in cardiac output or neuromuscular dysfunction. Oxygen should be used with caution after massive chlorine inhalation, and the need for early assisted ventilation should be assessed in victims.

AICAR Administration Attenuates Hemorrhagic Hyperglycemia and Lowers Oxygen Debt in Anesthetized Male Rabbits.

PubMed

Huang, Yi; Ratz, Paul H; Miner, Amy S; Locke, Victoria A; Chen, Grace; Chen, Yang; Barbee, Robert W

2017-01-01

Background: Many strategies have been utilized to treat traumatic shock via improved oxygen delivery (DO 2 ), while fewer have been used to in an attempt to reduce oxygen demand (VO 2 ). The cellular energy sensor 5' adenosine monophosphate-activated protein kinase (AMPK) has the potential to modulate both whole-body DO 2 and VO 2 . Therefore, we determined the effect of the AMPK activator AICAR (5-aminoimidazole-4-carboxamide 1-β-D-ribonucleoside) given acutely or chronically on key metabolites, hemodynamics, and oxygen consumption/delivery before and during hemorrhage in anesthetized male rabbits. Methods: Chronically treated animals received AICAR (40 mg/kg/day, IV) for 10 days prior to hemorrhage, while rabbits in the acute study were infused with AICAR (7.5 mg/kg bolus, 2 mg/kg/min infusion) or vehicle (0.3 ml/kg saline bolus, 0.03 ml/kg/min infusion) IV for 2 h prior to severe hemorrhage. Both acutely and chronically treated animals were sedated (ketamine/xylazine cocktail) the morning of the terminal experiment and surgically prepared for hemorrhage, including the implantation of arterial and venous catheters (for blood removal/sampling and drug/vehicle administration) and thoracotomy for implantation of transit-time flow transducers (for cardiac output determination). Results: AICAR given acutely lowered arterial blood glucose and increased blood lactate levels before hemorrhage, and abolished the well-documented hemorrhage-induced hyperglycemia seen in vehicle treated animals. Animals given AICAR chronically had blunted hemorrhage-induced hyperglycemia without prior baseline changes. Chronically treated AICAR animals showed significantly lower lactate levels during hemorrhage. Rabbits receiving AICAR both acutely and chronically experienced similar falls in mean arterial pressure, cardiac output and hence DO 2 to their vehicle counterparts throughout the hemorrhage period. However, rabbits treated either acutely or chronically with AICAR accumulated lower

Non-invasive transdermal two-dimensional mapping of cutaneous oxygenation with a rapid-drying liquid bandage

PubMed Central

Li, Zongxi; Roussakis, Emmanuel; Koolen, Pieter G. L.; Ibrahim, Ahmed M. S.; Kim, Kuylhee; Rose, Lloyd F.; Wu, Jesse; Nichols, Alexander J.; Baek, Yunjung; Birngruber, Reginald; Apiou-Sbirlea, Gabriela; Matyal, Robina; Huang, Thomas; Chan, Rodney; Lin, Samuel J.; Evans, Conor L.

2014-01-01

Oxygen plays an important role in wound healing, as it is essential to biological functions such as cell proliferation, immune responses and collagen synthesis. Poor oxygenation is directly associated with the development of chronic ischemic wounds, which affect more than 6 million people each year in the United States alone at an estimated cost of $25 billion. Knowledge of oxygenation status is also important in the management of burns and skin grafts, as well as in a wide range of skin conditions. Despite the importance of the clinical determination of tissue oxygenation, there is a lack of rapid, user-friendly and quantitative diagnostic tools that allow for non-disruptive, continuous monitoring of oxygen content across large areas of skin and wounds to guide care and therapeutic decisions. In this work, we describe a sensitive, colorimetric, oxygen-sensing paint-on bandage for two-dimensional mapping of tissue oxygenation in skin, burns, and skin grafts. By embedding both an oxygen-sensing porphyrin-dendrimer phosphor and a reference dye in a liquid bandage matrix, we have created a liquid bandage that can be painted onto the skin surface and dries into a thin film that adheres tightly to the skin or wound topology. When captured by a camera-based imaging device, the oxygen-dependent phosphorescence emission of the bandage can be used to quantify and map both the pO2 and oxygen consumption of the underlying tissue. In this proof-of-principle study, we first demonstrate our system on a rat ischemic limb model to show its capabilities in sensing tissue ischemia. It is then tested on both ex vivo and in vivo porcine burn models to monitor the progression of burn injuries. Lastly, the bandage is applied to an in vivo porcine graft model for monitoring the integration of full- and partial-thickness skin grafts. PMID:25426308

The effect of normobaric oxygen in patients with acute stroke: a systematic review and meta-analysis.

PubMed

Ding, Jiayue; Zhou, Da; Sui, Meng; Meng, Ran; Chandra, Ankush; Han, Jie; Ding, Yuchuan; Ji, Xunming

2018-03-30

Background Normobaric oxygen (NBO) has received considerable attention due to controversial data in brain protection in patients with acute stroke. This study aims to analyze current data of NBO on brain protection as used in the clinic. Methods We searched for and reviewed relevant articles and references from Pubmed, Medline, Embase, Cochrane, and Clincialtrials.gov that were published prior to October 2017. Data from prospective studies were processed using RevMan5.0 software, provided by Cochrane collaboration and transformed using relevant formulas. Results A total of 11 prospective RCT studies including 6366 patients with acute stroke (NBO group, 3207; control group, 3159) were enrolled in this analysis. △NIHSS represented the values of NIHSS at 4, 24 h, or 7 days post-stroke minus baseline NIHSS. Compared to controls, there was a minor trend toward NBO benefits in short-term prognostic indices, as indicated by decreased ΔNIHSS at our defined time points. By contrast, NBO decreased Barthel Index scores between 3 and 7 months, and increased death rates at 3, 6 months, and 1 year, whereas, modified Rankin Scale scores between 3 and 6 months were unchanged. Conclusions The existing trends toward benefits revealed in this meta-analysis help us appreciate the promising value of NBO, although current evidence of NBO on improving clinical outcomes of stroke is insufficient. Well-designed multi-center clinical trials are encouraged and urgently needed to further explore the efficacy of NBO on brain protection.

Using oxygen at home - what to ask your doctor

MedlinePlus

... my house? What should I do in a restaurant or bar? Can my oxygen be in the ... Bronchiolitis Bronchitis - acute Chronic obstructive pulmonary disease Lung surgery Pneumonia - adults (community acquired) Patient Instructions Bronchiolitis - discharge ...

Electron-Deficient Near-Infrared Pt(II) and Pd(II) Benzoporphyrins with Dual Phosphorescence and Unusually Efficient Thermally Activated Delayed Fluorescence: First Demonstration of Simultaneous Oxygen and Temperature Sensing with a Single Emitter.

PubMed

Zach, Peter W; Freunberger, Stefan A; Klimant, Ingo; Borisov, Sergey M

2017-11-01

We report a family of Pt and Pd benzoporphyrin dyes with versatile photophysical properties and easy access from cheap and abundant chemicals. Attaching 4 or 8 alkylsulfone groups onto a meso-tetraphenyltetrabenzoporphyrin (TPTBP) macrocylcle renders the dyes highly soluble in organic solvents, photostable, and electron-deficient with the redox potential raised up to 0.65 V versus the parent porphyrin. The new dyes intensively absorb in the blue (Soret band, 440-480 nm) and in the red (Q-band, 620-650 nm) parts of the electromagnetic spectrum and show bright phosphorescence at room-temperature in the NIR with quantum yields up to 30% in solution. The small singlet-triplet energy gap yields unusually efficient thermally activated delayed fluorescence (TADF) at elevated temperatures in solution and in polymeric matrices with quantum yields as high as 27% at 120 °C, which is remarkable for benzoporphyrins. Apart from oxygen sensing, these properties enable unprecedented simultaneous, self-referenced oxygen and temperature sensing with a single indicator dye: whereas oxygen can be determined either via the decay time of phosphorescence or TADF, the temperature is accessed via the ratio of the two emissions. Moreover, the dyes are efficient sensitizers for triplet-triplet annihilation (TTA)-based upconversion making possible longer sensitization wavelength than the conventional benzoporphyrin complexes. The Pt-octa-sulfone dye also features interesting semireversible transformation in basic media, which generates new NIR absorbing species.

[The clinical significance of microcirculation and oxygen metabolism evaluation in acute kidney injury assessment in patients with septic shock after resuscitation].

PubMed

Yu, C; Liu, D W; Wang, X T; He, H W; Pan, P; Xing, Z Q

2018-02-01

Objective: To evaluate the value of microcirculation and oxygen metabolism evaluation (MicrOME) in acute kidney injury(AKI) evaluation in patients with septic shock after resuscitation. Methods: Consecutive patients with septic shock after resuscitation and mechanical ventilation were enrolled from October 2016 to February 2017 in ICU at Peking Union Medical College Hospital.Patients were divided into 3 groups based on 10 min transcutaneous oxygen challenge test transcutaneous partial pressure of oxygen(PtcO(2))and venoarterial pressure of carbon dioxide difference (Pv-aCO(2)) /arteriovenous O(2) content difference (Ca-vO(2)) by blood gas analysis, i.e. group A [ΔPtcO(2)>66 mmHg(1 mmHg=0.133 kPa) and Pv-aCO(2)/Ca-vO(2)≤1.23], group B (ΔPtcO(2)≤66 mmHg), group C (ΔPtcO(2)>66 mmHg and Pv-aCO(2)/Ca-vO(2)>1.23). Heart rate,mean arterial pressure,central venous pressure,noradrenaline dose,lactate,Pv-aCO(2),Ca-vO(2), lactate clearance, central venous oxygen saturation(ScvO(2)) and liquid equilibrium were assessed after resuscitation.AKI staging based on Kidney Disease Global Improving Outcomes (KDIGO) clinical practice guideline was analyzed. The predictive value of lactate, ScvO(2), Pv-aCO(2)/Ca-vO(2) to progression of AKI after resuscitation was determined using receiver operating characteristic(ROC)curve analysis. Results: A total of 49 septic shock patients were enrolled including 30 males and 19 females with mean age of (61.10±17.10)years old.There were 19 patients in group A,21 patients in group B, and 9 patients in group C. Acute physiology and chronic health evaluation Ⅱ score was 20.92±7.19 and sequential organ failure assessment score 12.02±3.28. There were 4 patients with AKI and 1 progressed in group A, 11 patients with AKI and 2 progressed in group B, 6 patients with AKI and 4 progressed in group C. The cutoff value of Pv-aCO(2)/Ca-vO(2) was equal or more than 2.20 for predicting progression of AKI, resulting in a sensitivity of 85.7% and a

Prescribing Oxygen for Cluster Headache: A Guide for the Provider.

PubMed

Tepper, Stewart J; Duplin, Jessica; Nye, Barbara; Tepper, Deborah E

2017-10-01

Oxygen is the standard of care for acute treatment of cluster headache. CMS, the US Centers for Medicaid and Medicare Services, has made the indefensible decision to not cover oxygen for cluster headache for patients with Medicaid and Medicare insurance, despite the evidence and professional guidelines. Commercial insurance generally covers oxygen for cluster headache. This is a "how-to" guide for successfully prescribing oxygen in the US. Prescription information is provided that can be incorporated as dot phrases, smart sets, or other standard templates for prescribing oxygen for cluster patients. In many states, oxygen is affordable and can be prescribed for Medicaid and Medicare patients who wish to pay cash. Welding or nonmedical grade industrial oxygen is almost the same cost as medical oxygen. However, it is less pure, lacks the same inspection of tanks, and is delivered without regulators to provide appropriate flow rates. Patients who pay cash should be strongly encouraged to buy medical oxygen. © 2017 American Headache Society.

SnO2-gated AlGaN/GaN high electron mobility transistors based oxygen sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hung, S.T.; Chung, Chi-Jung; Chen, Chin Ching

2012-01-01

Hydrothermally grown SnO2 was integrated with AlGaN/GaN high electron mobility transistor (HEMT) sensor as the gate electrode for oxygen detection. The crystalline of the SnO2 was improved after annealing at 400 C. The grain growth kinetics of the SnO2 nanomaterials, together with the O2 gas sensing properties and sensing mechanism of the SnO2 gated HEMT sensors were investigated. Detection of 1% oxygen in nitrogen at 100 C was possible. A low operation temperature and low power consumption oxygen sensor can be achieved by combining the SnO2 films with the AlGaN/GaN HEMT structure

Structurally integrated organic light emitting device-based sensors for gas phase and dissolved oxygen.

PubMed

Shinar, Ruth; Zhou, Zhaoqun; Choudhury, Bhaskar; Shinar, Joseph

2006-05-24

A compact photoluminescence (PL)-based O2 sensor utilizing an organic light emitting device (OLED) as the light source is described. The sensor device is structurally integrated. That is, the sensing element and the light source, both typically thin films that are fabricated on separate glass substrates, are attached back-to-back. The sensing elements are based on the oxygen-sensitive dyes Pt- or Pd-octaethylporphyrin (PtOEP or PdOEP, respectively), which are embedded in a polystyrene (PS) matrix, or dissolved in solution. Their performance is compared to that of a sensing element based on tris(4,7-diphenyl-l,10-phenanthroline) Ru II (Ru(dpp)) embedded in a sol-gel film. A green OLED light source, based on tris(8-hydroxy quinoline Al (Alq3), was used to excite the porphyrin dyes; a blue OLED, based on 4,4'-bis(2,2'-diphenylviny1)-1,1'-biphenyl, was used to excite the Ru(dpp)-based sensing element. The O2 level was monitored in the gas phase and in water, ethanol, and toluene solutions by measuring changes in the PL lifetime tau of the O2-sensitive dyes. The sensor performance was evaluated in terms of the detection sensitivity, dynamic range, gas flow rate, and temperature effect, including the temperature dependence of tau in pure Ar and O2 atmospheres. The dependence of the sensitivity on the preparation procedure of the sensing film and on the PS and dye concentrations in the sensing element, whether a solid matrix or solution, were also evaluated. Typical values of the detection sensitivity in the gas phase, S(g) identical with tau(0% O2)/tau(100% O2), at 23 degrees C, were approximately 35 to approximately 50 for the [Alq3 OLED[/[PtOEP dye] pair; S(g) exceeded 200 for the Alq3/PdOEP sensor. For dissolved oxygen (DO) in water and ethanol, S(DO) (defined as the ratio of tau in de-oxygenated and oxygen-saturated solutions) was approximately 9.5 and approximately 11, respectively, using the PtOEP-based film sensor. The oxygen level in toluene was measured with Pt

Singlet Oxygen-Induced Membrane Disruption and Serpin-Protease Balance in Vacuolar-Driven Cell Death1[OPEN

PubMed Central

Carmieli, Raanan; Mor, Avishai; Fluhr, Robert

2016-01-01

Singlet oxygen plays a role in cellular stress either by providing direct toxicity or through signaling to initiate death programs. It was therefore of interest to examine cell death, as occurs in Arabidopsis, due to differentially localized singlet oxygen photosensitizers. The photosensitizers rose bengal (RB) and acridine orange (AO) were localized to the plasmalemma and vacuole, respectively. Their photoactivation led to cell death as measured by ion leakage. Cell death could be inhibited by the singlet oxygen scavenger histidine in treatments with AO but not with RB. In the case of AO treatment, the vacuolar membrane was observed to disintegrate. Concomitantly, a complex was formed between a vacuolar cell-death protease, RESPONSIVE TO DESSICATION-21 and its cognate cytoplasmic protease inhibitor ATSERPIN1. In the case of RB treatment, the tonoplast remained intact and no complex was formed. Over-expression of AtSerpin1 repressed cell death, only under AO photodynamic treatment. Interestingly, acute water stress showed accumulation of singlet oxygen as determined by fluorescence of Singlet Oxygen Sensor Green, by electron paramagnetic resonance spectroscopy and the induction of singlet oxygen marker genes. Cell death by acute water stress was inhibited by the singlet oxygen scavenger histidine and was accompanied by vacuolar collapse and the appearance of serpin-protease complex. Over-expression of AtSerpin1 also attenuated cell death under this mode of cell stress. Thus, acute water stress damage shows parallels to vacuole-mediated cell death where the generation of singlet oxygen may play a role. PMID:26884487

A method for measuring brain partial pressure of oxygen in unanesthetized unrestrained subjects: the effect of acute and chronic hypoxia on brain tissue PO(2).

PubMed

Ortiz-Prado, E; Natah, Siraj; Srinivasan, Sathyanarayanan; Dunn, Jeff F

2010-11-30

The level of tissue oxygenation provides information related to the balance between oxygen delivery, oxygen utilization, tissue reactivity and morphology during physiological conditions. Tissue partial pressure of oxygen (PtO(2)) is influenced by the use of anesthesia or restraint. These factors may impact the absolute level of PtO(2). In this study we present a novel fiber optic method to measure brain PtO(2). This method can be used in unanesthetized, unrestrained animals, provides absolute values for PO(2), has a stable calibration, does not consume oxygen and is MRI compatible. Brain PtO(2) was studied during acute hypoxia, as well as before and after 28 days of high altitude acclimatization. A sensor was chronically implanted in the frontal cortex of eight Wistar rats. It is comprised of a fiber optic probe with a tip containing material that fluoresces with an oxygen dependent lifetime. Brain PtO(2) declines by 80% and 76% pre- and post-acclimatization, respectively, when the fraction of inspired oxygen declines from 0.21 to 0.08. In addition, a linear relationship between brain PtO(2) and inspired O(2) levels was demonstrated r(2)=0.98 and r(2)=0.99 (pre- and post-acclimatization). Hypoxia acclimatization resulted in an increase in the overall brain PtO(2) by approximately 35%. This paper demonstrates the use of a novel chronically implanted fiber optic based sensor for measuring absolute PtO(2). It shows a very strong linear relationship in awake animals between inspired O(2) and tissue O(2), and shows that there is a proportional increase in PtO(2) over a range of inspired values after exposure to chronic hypoxia. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of different seated positions on lung volume and oxygenation in acute respiratory distress syndrome.

PubMed

Dellamonica, J; Lerolle, N; Sargentini, C; Hubert, S; Beduneau, G; Di Marco, F; Mercat, A; Diehl, J L; Richard, J C M; Bernardin, G; Brochard, L

2013-06-01

Lung volume available for ventilation is markedly decreased during acute respiratory distress syndrome. Body positioning may contribute to increase lung volume and partial verticalization is simple to perform. This study evaluated whether verticalization had parallel effects on oxygenation and end expiratory lung volume (EELV). Prospective multicenter study in 40 mechanically ventilated patients with ALI/ARDS in five university hospital MICUs. We evaluated four 45-min successive trunk position epochs (supine slightly elevated at 15°; semi recumbent with trunk elevated at 45°; seated with trunk elevated at 60° and legs down at 45°; back to supine). Arterial blood gases, EELV measured using the nitrogen washin/washout, and static compliance were measured. Responders were defined by a PaO₂/FiO₂ increase >20 % between supine and seated position. Results are median [25th-75th percentiles]. With median PEEP = 10 cmH₂O, verticalization increased lung volume but only responders (13 patients, 32 %) had a significant increase in EELV/PBW (predicted body weight) compared to baseline. This increase persisted at least partially when patients were positioned back to supine. Responders had a lower EELV/PBW supine [14 mL/kg (13-15) vs. 18 mL/kg (15-27) (p = 0.005)] and a lower compliance [30 mL/cmH₂O (22-38) vs. 42 (30-46) (p = 0.01)] than non-responders. Strain decreased with verticalization for responders. EELV/PBW increase and PaO₂/FiO₂ increase were not correlated. Verticalization is easily achieved and improves oxygenation in approximately 32 % of the patients together with an increase in EELV. Nonetheless, effect of verticalization on EELV/PBW is not predictable by PaO₂/FiO₂ increase, its monitoring may be helpful for strain optimization.

A mitochondrial redox oxygen sensor in the pulmonary vasculature and ductus arteriosus.

PubMed

Dunham-Snary, Kimberly J; Hong, Zhigang G; Xiong, Ping Y; Del Paggio, Joseph C; Herr, Julia E; Johri, Amer M; Archer, Stephen L

2016-01-01

The mammalian homeostatic oxygen sensing system (HOSS) initiates changes in vascular tone, respiration, and neurosecretion that optimize oxygen uptake and tissue oxygen delivery within seconds of detecting altered environmental or arterial PO2. The HOSS includes carotid body type 1 cells, adrenomedullary cells, neuroepithelial bodies, and smooth muscle cells (SMCs) in pulmonary arteries (PAs), ductus arteriosus (DA), and fetoplacental arteries. Hypoxic pulmonary vasoconstriction (HPV) optimizes ventilation-perfusion matching. In utero, HPV diverts placentally oxygenated blood from the non-ventilated lung through the DA. At birth, increased alveolar and arterial oxygen tension dilates the pulmonary vasculature and constricts the DA, respectively, thereby transitioning the newborn to an air-breathing organism. Though modulated by endothelial-derived relaxing and constricting factors, O2 sensing is intrinsic to PASMCs and DASMCs. Within the SMC's dynamic mitochondrial network, changes in PO2 alter the reduction-oxidation state of redox couples (NAD(+)/NADH, NADP(+)/NADPH) and the production of reactive oxygen species, ROS (e.g., H2O2), by complexes I and III of the electron transport chain (ETC). ROS and redox couples regulate ion channels, transporters, and enzymes, changing intracellular calcium [Ca(2+)]i and calcium sensitivity and eliciting homeostatic responses to hypoxia. In PASMCs, hypoxia inhibits ROS production and reduces redox couples, thereby inhibiting O2-sensitive voltage-gated potassium (Kv) channels, depolarizing the plasma membrane, activating voltage-gated calcium channels (CaL), increasing [Ca(2+)]i, and causing vasoconstriction. In DASMCs, elevated PO2 causes mitochondrial fission, increasing ETC complex I activity and ROS production. The DASMC's downstream response to elevated PO2 (Kv channel inhibition, CaL activation, increased [Ca(2+)]i, and rho kinase activation) is similar to the PASMC's hypoxic response. Impaired O2 sensing contributes to

Intracellular diffusion of oxygen and hypoxic sensing: role of mitochondrial respiration.

PubMed

Takahashi, Eiji; Sato, Michihiko

2010-01-01

In vivo, diffusional O(2) gradients from the capillary blood to the intracellular space determine O(2) availability at the O(2) sensing molecules in the cell. With a novel technique for imaging intracellular O(2) levels using green fluorescent protein (GFP), we examined the possibility that diffusional O(2) concentration gradients might be involved in the cellular hypoxic sensing in cultured Hep3B cells. In the present study, we failed to demonstrate significant gradients of intracellular O(2) when mitochondrial respiration was maximally elevated by an uncoupler of oxidative phosphorylation. Thus, we conclude that intracellular O(2) gradients may be negligible at normal mitochondrial O(2) demand in these cells.

Survey of Oxygen Delivery Practices in UK Paediatric Intensive Care Units

PubMed Central

Peters, Mark J.

2016-01-01

Purpose. Administration of supplemental oxygen is common in paediatric intensive care. We explored the current practice of oxygen administration using a case vignette in paediatric intensive care units (PICU) in the united kingdom. Methods. We conducted an online survey of Paediatric Intensive Care Society members in the UK. The survey outlined a clinical scenario followed by questions on oxygenation targets for 5 common diagnoses seen in critically ill children. Results. Fifty-three paediatric intensive care unit members from 10 institutions completed the survey. In a child with moderate ventilatory requirements, 21 respondents (42%) did not follow arterial partial pressure of oxygen (PaO2) targets. In acute respiratory distress syndrome, cardiac arrest, and sepsis, there was a trend to aim for lower PaO2 as the fraction of inspired oxygen (FiO2) increased. Conversely, in traumatic brain injury and pulmonary hypertension, respondents aimed for normal PaO2 even as the FiO2 increased. Conclusions. In this sample of clinicians PaO2 targets were not commonly used. Clinicians target lower PaO2 as FiO2 increases in acute respiratory distress syndrome, cardiac arrest, and sepsis whilst targeting normal range irrespective of FiO2 in traumatic brain injury and pulmonary hypertension. PMID:27516901

Acute exposure of mercury chloride stimulates the tissue regeneration program and reactive oxygen species production in the Drosophila midgut.

PubMed

Chen, Zhi; Wu, Xiaochun; Luo, Hongjie; Zhao, Lingling; Ji, Xin; Qiao, Xianfeng; Jin, Yaping; Liu, Wei

2016-01-01

We used Drosophila as an animal model to study the digestive tract in response to the exposure of inorganic mercury (HgCl2). We found that after oral administration, mercury was mainly sequestered within the midgut. This resulted in increased cell death, which in turn stimulated the tissue regeneration program, including accelerated proliferation and differentiation of the intestinal stem cells (ISCs). We further demonstrated that these injuries correlate closely with the excessive production of the reactive oxygen species (ROS), as vitamin E, an antioxidant reagent, efficiently suppressed the HgCl2-induced phenotypes of midgut and improved the viability. We propose that the Drosophila midgut could serve as a suitable model to study the treatment of acute hydrargyrism on the digestive systems. Copyright © 2015 Elsevier B.V. All rights reserved.

The effects of breathing a helium-oxygen gas mixture on maximal pulmonary ventilation and maximal oxygen consumption during exercise in acute moderate hypobaric hypoxia.

PubMed

Ogawa, Takeshi; Calbet, Jose A L; Honda, Yasushi; Fujii, Naoto; Nishiyasu, Takeshi

2010-11-01

To test the hypothesis that maximal exercise pulmonary ventilation (VE max) is a limiting factor affecting maximal oxygen uptake (VO2 max) in moderate hypobaric hypoxia (H), we examined the effect of breathing a helium-oxygen gas mixture (He-O(2); 20.9% O(2)), which would reduce air density and would be expected to increase VE max. Fourteen healthy young male subjects performed incremental treadmill running tests to exhaustion in normobaric normoxia (N; sea level) and in H (atmospheric pressure equivalent to 2,500 m above sea level). These exercise tests were carried out under three conditions [H with He-O(2), H with normal air and N] in random order. VO2 max and arterial oxy-hemoglobin saturation (SaO(2)) were, respectively, 15.2, 7.5 and 4.0% higher (all p < 0.05) with He-O(2) than with normal air (VE max, 171.9 ± 16.1 vs. 150.1 ± 16.9 L/min; VO2 max, 52.50 ± 9.13 vs. 48.72 ± 5.35 mL/kg/min; arterial oxyhemoglobin saturation (SaO(2)), 79 ± 3 vs. 76 ± 3%). There was a linear relationship between the increment in VE max and the increment in VO2 max in H (r = 0.77; p < 0.05). When subjects were divided into two groups based on their VO2 max, both groups showed increased VE max and SaO(2) in H with He-O(2), but VO2 max was increased only in the high VO2 max group. These findings suggest that in acute moderate hypobaric hypoxia, air-flow resistance can be a limiting factor affecting VE max; consequently, VO2 max is limited in part by VE max especially in subjects with high VO2 max.

An algorithm for sensing venous oxygenation using ultrasound-modulated light enhanced by microbubbles

NASA Astrophysics Data System (ADS)

Honeysett, Jack E.; Stride, Eleanor; Deng, Jing; Leung, Terence S.

2012-02-01

Near-infrared spectroscopy (NIRS) can provide an estimate of the mean oxygen saturation in tissue. This technique is limited by optical scattering, which reduces the spatial resolution of the measurement, and by absorption, which makes the measurement insensitive to oxygenation changes in larger deep blood vessels relative to that in the superficial tissue. Acousto-optic (AO) techniques which combine focused ultrasound (US) with diffuse light have been shown to improve the spatial resolution as a result of US-modulation of the light signal, however this technique still suffers from low signal-to-noise when detecting a signal from regions of high optical absorption. Combining an US contrast agent with this hybrid technique has been proposed to amplify an AO signal. Microbubbles are a clinical contrast agent used in diagnostic US for their ability to resonate in a sound field: in this work we also make use of their optical scattering properties (modelled using Mie theory). A perturbation Monte Carlo (pMC) model of light transport in a highly absorbing blood vessel containing microbubbles surrounded by tissue is used to calculate the AO signal detected on the top surface of the tissue. An algorithm based on the modified Beer-Lambert law is derived which expresses intravenous oxygen saturation in terms of an AO signal. This is used to determine the oxygen saturation in the blood vessel from a dual wavelength microbubble-contrast AO measurement. Applying this algorithm to the simulation data shows that the venous oxygen saturation is accurately recovered, and this measurement is robust to changes in the oxygenation of the superficial tissue layer.

The Complex Relationship of Extracorporeal Membrane Oxygenation and Acute Kidney Injury: Causation or Association?

PubMed

Kilburn, Daniel J; Shekar, Kiran; Fraser, John F

2016-01-01

Extracorporeal membrane oxygenation (ECMO) is a modified cardiopulmonary bypass (CPB) circuit capable of providing prolonged cardiorespiratory support. Recent advancement in ECMO technology has resulted in increased utilisation and clinical application. It can be used as a bridge-to-recovery, bridge-to-bridge, bridge-to-transplant, or bridge-to-decision. ECMO can restitute physiology in critically ill patients, which may minimise the risk of progressive multiorgan dysfunction. Alternatively, iatrogenic complications of ECMO clearly contribute to worse outcomes. These factors affect the risk : benefit ratio of ECMO which ultimately influence commencement/timing of ECMO. The complex interplay of pre-ECMO, ECMO, and post-ECMO pathophysiological processes are responsible for the substantial increased incidence of ECMO-associated acute kidney injury (EAKI). The development of EAKI significantly contributes to morbidity and mortality; however, there is a lack of evidence defining a potential benefit or causative link between ECMO and AKI. This area warrants investigation as further research will delineate the mechanisms involved and subsequent strategies to minimise the risk of EAKI. This review summarizes the current literature of ECMO and AKI, considers the possible benefits and risks of ECMO on renal function, outlines the related pathophysiology, highlights relevant investigative tools, and ultimately suggests an approach for future research into this under investigated area of critical care.

A critical role of acute bronchoconstriction in the mortality associated with high-dose sarin inhalation: Effects of epinephrine and oxygen therapies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gundavarapu, Sravanthi; Zhuang, Jianguo; Barrett, Edward G.

Sarin is an organophosphate nerve agent that is among the most lethal chemical toxins known to mankind. Because of its vaporization properties and ease and low cost of production, sarin is the nerve agent with a strong potential for use by terrorists and rouge nations. The primary route of sarin exposure is through inhalation and, depending on the dose, sarin leads to acute respiratory failure and death. The mechanism(s) of sarin-induced respiratory failure is poorly understood. Sarin irreversibly inhibits acetylcholine esterase, leading to excessive synaptic levels of acetylcholine and, we have previously shown that sarin causes marked ventilatory changes includingmore » weakened response to hypoxia. We now show that LD{sub 50} sarin inhalation causes severe bronchoconstriction in rats, leading to airway resistance, increased hypoxia-induced factor-1α, and severe lung epithelium injury. Transferring animals into 60% oxygen chambers after sarin exposure improved the survival from about 50% to 75% at 24 h; however, many animals died within hours after removal from the oxygen chambers. On the other hand, if LD{sub 50} sarin-exposed animals were administered the bronchodilator epinephrine, > 90% of the animals survived. Moreover, while both epinephrine and oxygen treatments moderated cardiorespiratory parameters, the proinflammatory cytokine surge, and elevated expression of hypoxia-induced factor-1α, only epinephrine consistently reduced the sarin-induced bronchoconstriction. These data suggest that severe bronchoconstriction is a critical factor in the mortality induced by LD{sub 50} sarin inhalation, and epinephrine may limit the ventilatory, inflammatory, and lethal effects of sarin. - Highlights: • Inhalation exposure of rats to LD{sub 50} sarin causes death through respiratory failure. • Severe bronchoconstriction is the major cause of sarin-induced respiratory failure. • Transfer of sarin exposed rats to 60% oxygen improves the mortality temporarily

Determination of the Role of Oxygen in Suspected Acute Myocardial Infarction by Biomarkers

ClinicalTrials.gov

2017-12-08

Acute Myocardial Infarction (AMI); Acute Coronary Syndrome (ACS); ST Elevation (STEMI) Myocardial Infarction; Ischemic Reperfusion Injury; Non-ST Elevation (NSTEMI) Myocardial Infarction; Angina, Unstable

Oxygen enrichment and its application to life support systems for workers in high-altitude areas

PubMed Central

Li, Yongling; Liu, Yingshu

2014-01-01

Background: Workers coming from lowland regions are at risk of developing acute mountain sickness (AMS) when working in low oxygen high-altitude areas. Objectives: The aim of this study was to improve the conditions that lead to hypoxia and ensure the safety of the high-altitude workers. We analyzed the influence of low atmospheric pressure on the oxygen enrichment process in high-altitude areas using an engineering method called low-pressure swing adsorption (LPSA). Methods: Fourteen male subjects were screened and divided into three groups by type of oxygen supply system used: (1) oxygen cylinder group; (2) LPSA oxygen dispersal group; and (3) control group. These tests included arterial oxygen saturation (SaO2), pulse rate (PR), breaths per minute (BPM), and blood pressure (BP). Results: The results showed that after supplying oxygen using the LPSA method at the tunnel face, the SaO2 of workers increased; the incidence of acute mountain sickness, PR, and BPM significantly decreased. Conclusions: The LPSA life support system was found to be a simple, convenient, efficient, reliable, and applicable approach to ensure proper working conditions at construction sites in high-altitude areas. PMID:25000108

Association of physical examination with pulmonary artery catheter parameters in acute lung injury.

PubMed

Grissom, Colin K; Morris, Alan H; Lanken, Paul N; Ancukiewicz, Marek; Orme, James F; Schoenfeld, David A; Thompson, B Taylor

2009-10-01

To correlate physical examination findings, central venous pressure, fluid output, and central venous oxygen saturation with pulmonary artery catheter parameters. Retrospective study. Data from the multicenter Fluid and Catheter Treatment Trial of the National Institutes of Health Acute Respiratory Distress Syndrome Network. Five hundred thirteen patients with acute lung injury randomized to treatment with a pulmonary artery catheter. Correlation of physical examination findings (capillary refill time >2 secs, knee mottling, or cool extremities), central venous pressure, fluid output, and central venous oxygen saturation with parameters from a pulmonary artery catheter. We determined association of baseline physical examination findings and on-study parameters of central venous pressure and central venous oxygen saturation with cardiac index <2.5 L/min/m2 and mixed venous oxygen saturation <60%. We determined correlation of baseline central venous oxygen saturation and mixed venous oxygen saturation and predictive value of a low central venous oxygen saturation for a low mixed venous oxygen saturation. Prevalence of cardiac index <2.5 and mixed venous oxygen saturation <60% was 8.1% and 15.5%, respectively. Baseline presence of all three physical examination findings had low sensitivity (12% and 8%), high specificity (98% and 99%), low positive predictive value (40% and 56%), but high negative predictive value (93% and 86%) for cardiac index <2.5 and mixed venous oxygen saturation <60%, respectively. Central venous oxygen saturation <70% predicted a mixed venous oxygen saturation <60% with a sensitivity 84%,specificity 70%, positive predictive value 31%, and negative predictive value of 96%. Low cardiac index correlated with cool extremities, high central venous pressure, and low 24-hr fluid output; and low mixed venous oxygen saturation correlated with knee mottling and high central venous pressure, but these correlations were not found to be clinically useful. In

Clinical Meaning of Early Oxygenation Improvement in Severe Acute Respiratory Distress Syndrome under Prolonged Prone Positioning

PubMed Central

Lee, Kwangha; Kim, Mi-Young; Yoo, Jung-Wan; Hong, Sang-Bum; Lim, Chae-Man

2010-01-01

Background/Aims Ventilating patients with acute respiratory distress syndrome (ARDS) in the prone position has been shown to improve arterial oxygenation, but prolonged prone positioning frequently requires continuous deep sedation, which may be harmful to patients. We evaluated the meaning of early gas exchange in patients with severe ARDS under prolonged (≥ 12 hours) prone positioning. Methods We retrospectively studied 96 patients (mean age, 60.1 ± 15.6 years; 75% men) with severe ARDS (PaO2/FiO2 ≤ 150 mmHg) admitted to a medical intensive care unit (MICU). The terms "PaO2 response" and "PaCO2 response" represented responses that resulted in increases in the PaO2/FiO2 ratio of ≥ 20 mmHg and decreases in PaCO2 of ≥ 1 mmHg, respectively, 8 to 12 hours after first placement in the prone position. Results The mean duration of prone positioning was 78.5 ± 61.2 hours, and the 28-day mortality rate after MICU admission was 56.3%. No significant difference in clinical characteristics was observed between PaO2 and PaCO2 responders and non-responders. The PaO2 responders after prone positioning showed an improved 28-day outcome, compared with non-responders by Kaplan-Meier survival estimates (p < 0.05 by the log-rank test), but the PaCO2 responders did not. Conclusions Our results suggest that the early oxygenation improvement after prone positioning might be associated with an improved 28-day outcome and may be an indicator to maintain prolonged prone positioning in patients with severe ARDS. PMID:20195404

Advanced COPD patients under home mechanical ventilation and/or long term oxygen therapy: Italian healthcare costs.

PubMed

Vitacca, M; Bianchi, L; Bazza, A; Clini, E M

2011-12-01

Little information is available on healthcare costs for patients with very severe chronic obstructive pulmonary disease. The aim of the current work was to evaluate Italian healthcare costs in these patients. Prospective 1-year analysis was assessed in three subgroups of patients; non-invasively ventilated (n=30); invasively-ventilated (n=12) and on long-term oxygen therapy (n=41). Acute costs for care were a sum of fees for doctor's consultations, admissions to hospital (ward and intensive care units) and emergency drugs. Chronic costs were the sum of costs for pharmacotherapy and home ventilation and/or oxygen care. Mean cost/day/patient was 96 +/- 112 Euro (range 9-526 Euro), with acute costs accounting for 72% and chronic costs for 28% of the total cost burden, with no significant differences in costs associated with the three subgroups. Acute costs had a non-normal distribution (range 0 to 510 Euro) being cost for hospitalisation the highest cost burden with more than 30% of acute care costs attributed to only a small segment of patients. Chronic care costs were also unevenly distributed among the various groups (ANOVA p = 0.006), being home oxygen supply the highest cost burden. The current Health Care System is in urgent need for a reassessment of the high cost burden associated with hospitalisations and home oxygen supply.

Reliable clarity automatic-evaluation method for optical remote sensing images

NASA Astrophysics Data System (ADS)

Qin, Bangyong; Shang, Ren; Li, Shengyang; Hei, Baoqin; Liu, Zhiwen

2015-10-01

Image clarity, which reflects the sharpness degree at the edge of objects in images, is an important quality evaluate index for optical remote sensing images. Scholars at home and abroad have done a lot of work on estimation of image clarity. At present, common clarity-estimation methods for digital images mainly include frequency-domain function methods, statistical parametric methods, gradient function methods and edge acutance methods. Frequency-domain function method is an accurate clarity-measure approach. However, its calculation process is complicate and cannot be carried out automatically. Statistical parametric methods and gradient function methods are both sensitive to clarity of images, while their results are easy to be affected by the complex degree of images. Edge acutance method is an effective approach for clarity estimate, while it needs picking out the edges manually. Due to the limits in accuracy, consistent or automation, these existing methods are not applicable to quality evaluation of optical remote sensing images. In this article, a new clarity-evaluation method, which is based on the principle of edge acutance algorithm, is proposed. In the new method, edge detection algorithm and gradient search algorithm are adopted to automatically search the object edges in images. Moreover, The calculation algorithm for edge sharpness has been improved. The new method has been tested with several groups of optical remote sensing images. Compared with the existing automatic evaluation methods, the new method perform better both in accuracy and consistency. Thus, the new method is an effective clarity evaluation method for optical remote sensing images.

[Non-invasive mechanical ventilation in the treatment of acute heart failure].

PubMed

Alfonso Megido, Joaquín; González Franco, Alvaro

2014-03-01

When acute heart failure progresses and there is acute cardiogenic pulmonary edema, routine therapeutic measures should be accompanied by other measures that help to correct oxygenation of the patient. The final and most drastic step is mechanical ventilation. Non-invasive ventilation has been developed in the last few years as a method that attempts to improve oxygenation without the need for intubation, thus, in theory, reducing morbidity and mortality in these patients. The present article describes the controversies surrounding the results of this technique and discusses its indications. The article also discusses how to start non-invasive ventilation in patients with acute pulmonary edema from a practical point of view. Copyright © 2014 Elsevier España, S.L. All rights reserved.

Oxygen cycling in the northern Benguela Upwelling System: Modelling oxygen sources and sinks

NASA Astrophysics Data System (ADS)

Schmidt, Martin; Eggert, Anja

2016-12-01

This paper elucidates the oxygen dynamics in the northern Benguela Upwelling System by means of process oriented, numerical modelling. Owing to the complex physical-biological interaction in this system, a coupled hydrodynamic-biogeochemical model is required to grasp the various aspects of the oxygen dynamics. We used high-resolution atmospheric fields derived from observations to force our model, available since 1999. The model results represent a 15 years, consistent data set of realistic hydrographic and ecosystem variables, including oxygen distribution patterns. After a concise description of the main aspects of the model, we use the model data to analyse the components contributing to the oxygen dynamics, namely, the ocean circulation, the exchange between ocean and atmosphere as well as the local biogeochemical oxygen cycling in the system. We thoroughly validate the model with available field observations and remote sensing data. The strengths of coastal upwelling, which controls the nutrient supply to the euphotic zone, as well as the poleward undercurrent that carries oxygen and nutrients to the shelf in the northern Benguela Upwelling System are well reproduced in the model. Among the biological oxygen sinks, mineralisation in the sediment, respiration of zooplankton and nitrification in the water column are important. We also found that vertical migration of zooplankton in response to the oxygen conditions provides a regulating feedback, which may prevent a complete deoxygenation of suboxic waters. As long as oxygen or nitrate are available in the bottom waters, the activities of chemolithoautotrophic sulphur bacteria on the sediment surface keep the redoxcline within the sediment and prevent the release of hydrogen sulphide into the water column. By horizontal integration of the simulated ocean-atmosphere oxygen flux, it can be shown that the Kunene upwelling cell between 16 ° S and 18 ° S is a boundary between the equatorial ocean, characterise by

[Value of early-stage cerebral oxygen utilization coefficient in predicting delayed encephalopathy after acute carbon monoxide poisoning].

PubMed

Liu, Q; Li, W; Li, N; Xiao, Q M; He, J Q; Wang, W Z; Qi, H N; Wang, P

2017-05-20

Objective: To investigate the dynamic change in cerebral oxygen utilization coefficient (O(2)UCc) in the early stage of acute severe carbon monoxide poisoning (ASCMP) and its value in predicting delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) . Methods: A prospective observational study was conducted for patients with ASCMP who were admitted to our hospital from November 2013 to March 2016, and their baseline features and physiological parameters were recorded. Observation ended at two months after acute poisoning; according to the presence or absence of DEACMP, the patients were divided into DEACMP group with 21 patients and non-DEACMP group with 64 patients. The change in O(2)UCc was monitored on admission and at 6, 24, 48, and 72 hours. Spearman correlation was used to investigate the correlation between O(2)UCc and Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and the receiver operating characteristic (ROC) curve was used to evaluate the accuracy of O(2)UCc in predicting DEACMP. Results: Both groups had a significant increase in O(2)UCc on admission, and the DEACMP group had a significantly greater increase than the non-DEACMP group (52.57%±9.30% vs 41.46±%6.37%, P <0.05) . Then both groups tended to have a reduction in O(2)UCc, and the DEACMP group had a significantly higher O(2)UCc than the non-DEACMP group at 6, 24, and 48 hours (47.40%±7.92%, 39.38%±8.01%, and 32.29%±6.31% vs 34.51%±7.89%, 28.79%±5.4%, and 27.72%±5.46%, P <0.05) . On admission and at 6, 24, and 48 hours, O2UCc was positively correlated with APACHE II score ( r =0.304, 0.398, 0.426, and 0.300, P =0.005, 0.000, 0.000, and 0.005) . The ROC curve showed that O(2)UCc had a value in predicting DEACMP on admission and at 6, 24, and 48 hours, and 6-hour O2UCc had the highest predictive value with an area under the ROC curve of 0.870 (95% confidence interval 0.794-0.947, P <0.05) . Conclusion: The dynamic change in O(2)UCc has a reference value in

Acute Respiratory Failure in Renal Transplant Recipients: A Single Intensive Care Unit Experience.

PubMed

Ulas, Aydin; Kaplan, Serife; Zeyneloglu, Pinar; Torgay, Adnan; Pirat, Arash; Haberal, Mehmet

2015-11-01

Frequency of pulmonary complications after renal transplant has been reported to range from 3% to 17%. The objective of this study was to evaluate renal transplant recipients admitted to an intensive care unit to identify incidence and cause of acute respiratory failure in the postoperative period and compare clinical features and outcomes between those with and without acute respiratory failure. We retrospectively screened the data of 540 consecutive adult renal transplant recipients who received their grafts at a single transplant center and included those patients admitted to an intensive care unit during this period for this study. Acute respiratory failure was defined as severe dyspnea, respiratory distress, decreased oxygen saturation, hypoxemia or hypercapnia on room air, or requirement of noninvasive or invasive mechanical ventilation. Among the 540 adult renal transplant recipients, 55 (10.7%) were admitted to an intensive care unit, including 26 (47.3%) admitted for acute respiratory failure. Median time from transplant to intensive care unit admission was 10 months (range, 0-67 mo). The leading causes of acute respiratory failure were bacterial pneumonia (56%) and cardiogenic pulmonary edema (44%). Mean partial pressure of arterial oxygen to fractional inspired oxygen ratio was 174 ± 59, invasive mechanical ventilation was used in 13 patients (50%), and noninvasive mechanical ventilation was used in 8 patients (31%). The overall mortality was 16.4%. Acute respiratory failure was the reason for intensive care unit admission in almost half of our renal transplant recipients. Main causes of acute respiratory failure were bacterial pneumonia and cardiogenic pulmonary edema. Mortality of patients admitted for acute respiratory failure was similar to those without acute respiratory failure.

Flexible Sheet-Type Sensor for Noninvasive Measurement of Cellular Oxygen Metabolism on a Culture Dish.

PubMed

Kojima, Mari; Takehara, Hiroaki; Akagi, Takanori; Shiono, Hirofumi; Ichiki, Takanori

2015-01-01

A novel flexible sensor was developed for the noninvasive oxygen metabolism measurement of cultivated cells and tissues. This device is composed of a transparent double-layered polymer sheet of ethylene-vinyl alcohol (EVOH) and poly(dimethylsiloxane) (PDMS) having an array of microhole structures of 90 μm diameter and 50 μm depth on its surface. All the microhole structures were equipped with a 1-μm-thick optical chemical sensing layer of platinum porphyrin-fluoropolymer on their bottom. The three-dimensional microstructures of the sensor were fabricated by a newly developed simple and low-cost production method named self-aligned hot embossing. The device was designed to be attached slightly above the cells cultivated on a dish to form a temporarily closed microspace over the target cells during measurement. Since the change in oxygen concentration is relatively fast in the microcompartmentalized culture medium, a rapid evaluation of the oxygen consumption rate is possible by measuring the phosphorescence lifetime of the platinum porphyrin-fluoropolymer. The combined use of the device and an automated optical measurement system enabled the high-throughput sensing of cellular oxygen consumption (100 points/min). We monitored the oxygen metabolism of the human breast cancer cell line MCF7 on a Petri dish and evaluated the oxygen consumption rate to be 0.72 ± 0.12 fmol/min/cell. Furthermore, to demonstrate the utility of the developed sensing system, we demonstrated the mapping of the oxygen consumption rate of rat brain slices and succeeded in visualizing a clear difference among the layer structures of the hippocampus, i.e., the cornu ammonis (CA1 and CA3) and dentate gyrus (DG).

Novel synthesis approach for stable sodium superoxide (NaO2) nanoparticles for LPG sensing application

NASA Astrophysics Data System (ADS)

Nemade, Kailash; Waghuley, Sandeep

2017-05-01

The synthesis of stable superoxide is still great challenge for the researchers working in the field of materials science. Through this letter, we report the novel and simple synthesis approach for the preparation of stable sodium superoxide (NaO2) nanoparticles. NaO2 nanoparticles were prepared by a spray pyrolysis technique, under oxygen rich environment for gas sensing application. The texture characterizations show that as-obtained NaO2 nanoparticles have high structural purity. Most importantly, NaO2 nanoparticles exhibits higher sensing response, shorter response time and recovery time, low operating temperature and good stability during sensing of liquefied petroleum gas (LPG). The main accomplishment of present work is that as-fabricated sensor has low operating temperature (423 K), which is below auto-ignition temperature of LPG. The gas sensing mechanism of NaO2 nanoparticles was discussed without the conventional oxygen bridging mechanism. Through this short communication, LPG sensing application of stable sodium superoxide nanoparticle is explored.

Hemodynamic parameters change earlier than tissue oxygen tension in hemorrhage.

PubMed

Pestel, Gunther J; Fukui, Kimiko; Kimberger, Oliver; Hager, Helmut; Kurz, Andrea; Hiltebrand, Luzius B

2010-05-15

Untreated hypovolemia results in impaired outcome. This study tests our hypothesis whether general hemodynamic parameters detect acute blood loss earlier than monitoring parameters of regional tissue beds. Eight pigs (23-25 kg) were anesthetized and mechanically ventilated. A pulmonary artery catheter and an arterial catheter were inserted. Tissue oxygen tension was measured with Clark-type electrodes in the jejunal and colonic wall, in the liver, and subcutaneously. Jejunal microcirculation was assessed by laser Doppler flowmetry (LDF). Intravascular volume was optimized using difference in pulse pressure (dPP) to keep dPP below 13%. Sixty minutes after preparation, baseline measurements were taken. At first, 5% of total blood volume was withdrawn, followed by another 5% increment, and then in 10% increments until death. After withdrawal of 5% of estimated blood volume, dPP increased from 6.1% +/- 3.0% to 20.8% +/- 2.7% (P < 0.01). Mean arterial pressure (MAP), mean pulmonary artery pressure (PAP) and pulmonary artery occlusion pressure (PAOP) decreased with a blood loss of 10% (P < 0.01). Cardiac output (CO) changed after a blood loss of 20% (P < 0.05). Tissue oxygen tension in central organs, and blood flow in the jejunal muscularis decreased (P < 0.05) after a blood loss of 20%. Tissue oxygen tension in the skin, and jejunal mucosa blood flow decreased (P < 0.05) after a blood loss of 40% and 50%, respectively. In this hemorrhagic pig model systemic hemodynamic parameters were more sensitive to detect acute hypovolemia than tissue oxygen tension measurements or jejunal LDF measurements. Acute blood loss was detected first by dPP. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Protein kinase G–regulated production of H2S governs oxygen sensing

PubMed Central

Yuan, Guoxiang; Vasavda, Chirag; Peng, Ying-Jie; Makarenko, Vladislav V.; Raghuraman, Gayatri; Nanduri, Jayasri; Gadalla, Moataz M.; Semenza, Gregg L.; Kumar, Ganesh K.; Snyder, Solomon H.; Prabhakar, Nanduri R.

2015-01-01

Reflexes initiated by the carotid body, the principal O2-sensing organ, are critical for maintaining cardio-respiratory homeostasis during hypoxia. O2 sensing by the carotid body requires carbon monoxide (CO) generation by heme oxygenase-2 (HO-2) and hydrogen sulfide (H2S) synthesis by cystathionine-γ-lyase (CSE). We report that O2 stimulated the generation of CO, but not that of H2S, and required two cysteine residues in the heme regulatory motif (Cys265 and Cys282) of HO-2. CO stimulated protein kinase G (PKG)–dependent phosphorylation of Ser377 of CSE, inhibiting the production of H2S. Hypoxia decreased the inhibition of CSE by reducing CO generation resulting in increased H2S, which stimulated carotid body neural activity. In carotid bodies from mice lacking HO-2, compensatory increased abundance of nNOS (neuronal nitric oxide synthase) mediated O2 sensing through PKG-dependent regulation of H2S by nitric oxide. These results provide a mechanism for how three gases work in concert in the carotid body to regulate breathing. PMID:25900831

Plant-mediated Sediment Oxygenation in Coastal Wetlands

NASA Astrophysics Data System (ADS)

Koop-Jakobsen, K.

2016-02-01

Belowground sediment oxygenation by wetland plants is an important mechanism controlling many microbial processes and chemical fluxes in coastal wetlands. Although transport of oxygen via the arenthyma tissue and subsequent oxygen loss across root surfaces is well-documented for Spartina grasses, only few studies have measured the oxygenation of sediment surrounding roots and rhizomes. In this study, the degree of sediment oxygenation in Spartina anglica rhizospheres was assessed in situ using a novel multifiber optode system inserting 100 oxygen sensing fiber optodes directly into the rhizosphere. Two closely located, but morphologically different, S. anglica populations growing in permeable sandy sediment and tidal flat deposit, respectively, were investigated. No oxygen was detected inside the rhizospheres at any depth in either location indicating that plant-mediated sediment oxygenation in S. anglica had a limited impact on the bulk anoxic sediment. This was substantiated by planar optode studies showing that sediment oxygenation was confined to the immediate vicinity of the root tips of adventitious root and root hairs stretching only up to 1.5mm away from the roots surface in permeable sandy sediment and 0.4mm in tidal flat deposit, which had a substantially higher oxygen demand. This contrasts previous studies estimating that more than half of the S. anglica rhizosphere volume may be oxygenated, and thereby suggests a high variability in the degree of sediment oxygenation among different S. anglica populations. Furthermore, there may be a significant difference in the degree of sediment oxygenation among different Spartina species; our recent in situ investigation of oxygen profiles in a Spartina alterniflora-dominated marsh suggested that oxygen leakage here may keep the bulk sediment at low oxygen concentration ranging from 0.5-4μM.

A mitochondrial redox oxygen sensor in the pulmonary vasculature and ductus arteriosus1

PubMed Central

Dunham-Snary, Kimberly J; Hong, Zhigang G; Xiong, Ping Y; Del Paggio, Joseph C; Herr, Julia E; Johri, Amer M; Archer, Stephen L

2015-01-01

The mammalian homeostatic oxygen sensing system (HOSS) initiates changes in vascular tone, respiration, and neurosecretion that optimize oxygen uptake and tissue oxygen delivery within seconds of detecting altered environmental or arterial PO2. The HOSS includes carotid body type 1 cells, adrenomedullary cells, neuroepithelial bodies, and smooth muscle cells (SMC) in pulmonary arteries (PA), ductus arteriosus (DA) and fetoplacental arteries. Hypoxic pulmonary vasoconstriction (HPV) optimises ventilation-perfusion matching. In utero, HPV diverts placentally-oxygenated blood from the non-ventilated lung through the DA. At birth, increased alveolar and arterial oxygen tension dilate the pulmonary vasculature and, constrict the DA, respectively, thereby transitioning the newborn to an air-breathing organism. Though modulated by endothelial-derived relaxing and constricting factors, O2-sensing is intrinsic to PA- and DASMCs. Within the SMC’s dynamic mitochondrial network, changes in PO2 alter the reduction-oxidation state of redox couples (NAD+/NADH, NADP+/NADPH) and the production of reactive oxygen species, ROS (e.g. H2O2) by Complexes I and III of the electron transport chain (ETC). ROS and redox couples regulate ion channels, transporters, and enzymes, changing intracellular calcium [Ca2+]i and calcium sensitivity and eliciting homeostatic responses to hypoxia. In PASMC, hypoxia inhibits ROS production and reduces redox couples, thereby inhibiting O2-sensitive voltage-gated potassium (Kv) channels, depolarizing the plasma membrane, activating voltage-gated calcium channels (CaL), increasing [Ca2+]i and causing vasoconstriction. In DASMC, elevated PO2 causes mitochondrial fission, increasing ETC Complex I activity and ROS production. The DASMC’s downstream response to elevated PO2 (Kv channel inhibition, CaL activation, increased [Ca2+]i and rho kinase activation) is similar to the PASMC’s hypoxic response. Impaired O2-sensing contributes to human diseases

Anaemia only causes a small reduction in the upper critical temperature of sea bass: is oxygen delivery the limiting factor for tolerance of acute warming in fishes?

PubMed

Wang, Tobias; Lefevre, Sjannie; Iversen, Nina K; Findorf, Inge; Buchanan, Rasmus; McKenzie, David J

2014-12-15

To address how the capacity for oxygen transport influences tolerance of acute warming in fishes, we investigated whether a reduction in haematocrit, by means of intra-peritoneal injection of the haemolytic agent phenylhydrazine, lowered the upper critical temperature of sea bass. A reduction in haematocrit from 42±2% to 20±3% (mean ± s.e.m.) caused a significant but minor reduction in upper critical temperature, from 35.8±0.1 to 35.1±0.2°C, with no correlation between individual values for haematocrit and upper thermal limit. Anaemia did not influence the rise in oxygen uptake between 25 and 33°C, because the anaemic fish were able to compensate for reduced blood oxygen carrying capacity with a significant increase in cardiac output. Therefore, in sea bass the upper critical temperature, at which they lost equilibrium, was not determined by an inability of the cardio-respiratory system to meet the thermal acceleration of metabolic demands. © 2014. Published by The Company of Biologists Ltd.

[EFFICIENCY OF COMBINATION OF ROFLUMILAST AND QUERCETIN FOR CORRECTION OXYGEN- INDEPENDENT MECHANISMS AND PHAGOCYTIC ACTIVITY OF MACROPHAGE CELLS OF PATIENTS WITH ACUTE EXACERBATION OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE WHEN COMBINED WITH CORONARY HEART DISEASE].

PubMed

Gerych, P; Yatsyshyn, R

2015-01-01

Studied oxygen independent reaction and phagocytic activity of macrophage cells of patients with chronic obstructive pulmonary disease (COPD) II-III stage when combined with coronary heart disease (CHD). The increasing oxygen independent reactions monocytes and neutrophils and a decrease of the parameters that characterize the functional state of phagocytic cells, indicating a decrease in the functional capacity of macrophage phagocytic system (MPS) in patients with acute exacerbation of COPD, which runs as its own or in combination with stable coronary heart disease angina I-II. FC. Severity immunodeficiency state in terms of cellular component of nonspecific immunity in patients with acute exacerbation of COPD II-III stage in conjunction with the accompanying CHD increases with the progression of heart failure. Inclusion of basic therapy of COPD exacerbation and standard treatment of coronary artery disease and drug combinations Roflumilastand quercetin causes normalization of phagocytic indices MFS, indicating improved immune status and improves myocardial perfusion in terms of daily ECG monitoring.

Pediatric Acute Respiratory Distress Syndrome in Pediatric Allogeneic Hematopoietic Stem Cell Transplants: A Multicenter Study.

PubMed

Rowan, Courtney M; Smith, Lincoln S; Loomis, Ashley; McArthur, Jennifer; Gertz, Shira J; Fitzgerald, Julie C; Nitu, Mara E; Moser, Elizabeth A S; Hsing, Deyin D; Duncan, Christine N; Mahadeo, Kris M; Moffet, Jerelyn; Hall, Mark W; Pinos, Emily L; Tamburro, Robert F; Cheifetz, Ira M

2017-04-01

Immunodeficiency is both a preexisting condition and a risk factor for mortality in pediatric acute respiratory distress syndrome. We describe a series of pediatric allogeneic hematopoietic stem cell transplant patients with pediatric acute respiratory distress syndrome based on the recent Pediatric Acute Lung Injury Consensus Conference guidelines with the objective to better define survival of this population. Secondary analysis of a retrospective database. Twelve U.S. pediatric centers. Pediatric allogeneic hematopoietic stem cell transplant recipients requiring mechanical ventilation. None. During the first week of mechanical ventilation, patients were categorized as: no pediatric acute respiratory distress syndrome or mild, moderate, or severe pediatric acute respiratory distress syndrome based on oxygenation index or oxygen saturation index. Univariable logistic regression evaluated the association between pediatric acute respiratory distress syndrome and PICU mortality. A total of 91.5% of the 211 patients met criteria for pediatric acute respiratory distress syndrome using the Pediatric Acute Lung Injury Consensus Conference definition: 61.1% were severe, 27.5% moderate, and 11.4% mild. Overall survival was 39.3%. Survival decreased with worsening pediatric acute respiratory distress syndrome: no pediatric acute respiratory distress syndrome 66.7%, mild 63.6%, odds ratio = 1.1 (95% CI, 0.3-4.2; p = 0.84), moderate 52.8%, odds ratio = 1.8 (95% CI, 0.6-5.5; p = 0.31), and severe 24.6%, odds ratio = 6.1 (95% CI, 2.1-17.8; p < 0.001). Nonsurvivors were more likely to have multiple consecutive days at moderate and severe pediatric acute respiratory distress syndrome (p < 0.001). Moderate and severe patients had longer PICU length of stay (p = 0.01) and longer mechanical ventilation course (p = 0.02) when compared with those with mild or no pediatric acute respiratory distress syndrome. Nonsurvivors had a higher median maximum oxygenation index than survivors at

Oxygen, the lead actor in the pathophysiologic drama: enactment of the trinity of normoxia, hypoxia, and hyperoxia in disease and therapy.

PubMed

Kulkarni, Aditi C; Kuppusamy, Periannan; Parinandi, Narasimham

2007-10-01

Aerobic life has evolved a dependence on molecular oxygen for its mere survival. Mitochondrial oxidative phosphorylation absolutely requires oxygen to generate the currency of energy in aerobes. The physiologic homeostasis of these organisms is strictly maintained by optimal cellular and tissue-oxygenation status through complex oxygen-sensing mechanisms, signaling cascades, and transport processes. In the event of fluctuating oxygen levels leading to either an increase (hyperoxia) or decrease (hypoxia) in cellular oxygen, the organism faces a crisis involving depletion of energy reserves, altered cell-signaling cascades, oxidative reactions/events, and cell death or tissue damage. Molecular oxygen is activated by both nonenzymatic and enzymatic mechanisms into highly reactive oxygen species (ROS). Aerobes have evolved effective antioxidant defenses to counteract the reactivity of ROS. Although the ROS are also required for many normal physiologic functions of the aerobes, overwhelming production of ROS coupled with their insufficient scavenging by endogenous antioxidants will lead to detrimental oxidative stress. Needless to say, molecular oxygen is at the center of oxygenation, oxidative phosphorylation, and oxidative stress. This review focuses on the biology and pathophysiology of oxygen, with an emphasis on transport, sensing, and activation of oxygen, oxidative phosphorylation, oxygenation, oxidative stress, and oxygen therapy.

NO.sub.x sensing devices having conductive oxide electrodes

DOEpatents

Montgomery, Frederick C.; West, David L.; Armstrong, Timothy R.; Maxey, Lonnie C.

2010-03-16

A NO.sub.x sensing device includes at least one pair of spaced electrodes, at least one of which is made of a conductive oxide, and an oxygen-ion conducting material in bridging electrical communication with the electrodes.

Duration of effects of acute environmental changes on food anticipatory behaviour, feed intake, oxygen consumption, and cortisol release in Atlantic salmon parr.

PubMed

Folkedal, Ole; Torgersen, Thomas; Olsen, Rolf Erik; Fernö, Anders; Nilsson, Jonatan; Oppedal, Frode; Stien, Lars H; Kristiansen, Tore S

2012-01-18

We compared behavioural and physiological responses and recovery time after different acute environmental challenges in groups of salmon parr. The fish were prior to the study conditioned to a flashing light signalling arrival of food 30 s later to study if the strength of Pavlovian conditioned food anticipatory behaviour can be used to assess how salmon parr cope with various challenges. The effect on anticipatory behaviour was compared to the effect on feed intake and physiological responses of oxygen hyper-consumption and cortisol excretion. The challenges were temperature fluctuation (6.5C° over 4 h), hyperoxia (up to 380% O(2) saturation over 4 h), and intense chasing for 10 min. Cortisol excretion was only elevated after hyperoxia and chasing, and returned to baseline levels after around 3 h or less. Oxygen hyper-consumption persisted for even shorter periods. Feed intake was reduced the first feeding after all challenges and recovered within 3 h after temperature and hyperoxia, but was reduced for days after chasing. Food anticipatory behaviour was reduced for a longer period than feed intake after hyperoxia and was low at least 6 h after chasing. Our findings suggest that a recovery of challenged Atlantic salmon parr to baseline levels of cortisol excretion and oxygen consumption does not mean full recovery of all psychological and physiological effects of environmental challenges, and emphasise the need for measuring several factors including behavioural parameters when assessing fish welfare. Copyright © 2011 Elsevier Inc. All rights reserved.

Multiplexed fibre optic sensing in the distal lung (Conference Presentation)

NASA Astrophysics Data System (ADS)

Choudhary, Tushar R.; Tanner, Michael G.; Megia-Fernandez, Alicia; Harrington, Kerrianne; Wood, Harry A.; Chankeshwara, Sunay; Zhu, Patricia; Choudhury, Debaditya; Yu, Fei; Thomson, Robert R.; Duncan, Rory R.; Dhaliwal, Kevin; Bradley, Mark

2017-02-01

We present a toolkit for a multiplexed pH and oxygen sensing probe in the distal lung using multicore fibres. Measuring physiological relevant parameters like pH and oxygen is of significant importance in understanding changes associated with disease pathology. We present here, a single multicore fibre based pH and oxygen sensing probe which can be used with a standard bronchoscope to perform in vivo measurements in the distal lung. The multiplexed probe consists of fluorescent pH sensors (fluorescein based) and oxygen sensors (Palladium porphyrin complex based) covalently bonded to silica microspheres (10 µm) loaded on the distal facet of a 19 core (10 µm core diameter) multicore fibre (total diameter of 150 µm excluding coating). Pits are formed by selectively etching the cores using hydrofluoric acid, multiplexing is achieved through the self-location of individual probes on differing cores. This architecture can be expanded to include probes for further parameters. Robust measurements are demonstrated of self-referencing fluorophores, not limited by photobleaching, with short (100ms) measurement times at low ( 10µW) illumination powers. We have performed on bench calibration and tests of in vitro tissue models and in an ovine whole lung model to validate our sensors. The pH sensor is demonstrated in the physiologically relevant range of pH 5 to pH 8.5 and with an accuracy of ± 0.05 pH units. The oxygen sensor is demonstrated in gas mixtures downwards from 20% oxygen and in liquid saturated with 20% oxygen mixtures ( 8mg/L) down to full depletion (0mg/L) with 0.5mg/L accuracy.

Spontaneously regulated vs. controlled ventilation of acute lung injury/acute respiratory distress syndrome.

PubMed

Marini, John J

2011-02-01

To present an updated discussion of those aspects of controlled positive pressure breathing and retained spontaneous regulation of breathing that impact the management of patients whose tissue oxygenation is compromised by acute lung injury. The recent introduction of ventilation techniques geared toward integrating natural breathing rhythms into even the earliest phase of acute respiratory distress syndrome support (e.g., airway pressure release, proportional assist ventilation, and neurally adjusted ventilatory assist), has stimulated a burst of new investigations. Optimizing gas exchange, avoiding lung injury, and preserving respiratory muscle strength and endurance are vital therapeutic objectives for managing acute lung injury. Accordingly, comparing the physiology and consequences of breathing patterns that preserve and eliminate breathing effort has been a theme of persisting investigative interest throughout the several decades over which it has been possible to sustain cardiopulmonary life support outside the operating theater.

Self-Powered Wireless Carbohydrate/Oxygen Sensitive Biodevice Based on Radio Signal Transmission

PubMed Central

Falk, Magnus; Alcalde, Miguel; Bartlett, Philip N.; De Lacey, Antonio L.; Gorton, Lo; Gutierrez-Sanchez, Cristina; Haddad, Raoudha; Kilburn, Jeremy; Leech, Dónal; Ludwig, Roland; Magner, Edmond; Mate, Diana M.; Conghaile, Peter Ó.; Ortiz, Roberto; Pita, Marcos; Pöller, Sascha; Ruzgas, Tautgirdas; Salaj-Kosla, Urszula; Schuhmann, Wolfgang; Sebelius, Fredrik; Shao, Minling; Stoica, Leonard; Sygmund, Cristoph; Tilly, Jonas; Toscano, Miguel D.; Vivekananthan, Jeevanthi; Wright, Emma; Shleev, Sergey

2014-01-01

Here for the first time, we detail self-contained (wireless and self-powered) biodevices with wireless signal transmission. Specifically, we demonstrate the operation of self-sustained carbohydrate and oxygen sensitive biodevices, consisting of a wireless electronic unit, radio transmitter and separate sensing bioelectrodes, supplied with electrical energy from a combined multi-enzyme fuel cell generating sufficient current at required voltage to power the electronics. A carbohydrate/oxygen enzymatic fuel cell was assembled by comparing the performance of a range of different bioelectrodes followed by selection of the most suitable, stable combination. Carbohydrates (viz. lactose for the demonstration) and oxygen were also chosen as bioanalytes, being important biomarkers, to demonstrate the operation of the self-contained biosensing device, employing enzyme-modified bioelectrodes to enable the actual sensing. A wireless electronic unit, consisting of a micropotentiostat, an energy harvesting module (voltage amplifier together with a capacitor), and a radio microchip, were designed to enable the biofuel cell to be used as a power supply for managing the sensing devices and for wireless data transmission. The electronic system used required current and voltages greater than 44 µA and 0.57 V, respectively to operate; which the biofuel cell was capable of providing, when placed in a carbohydrate and oxygen containing buffer. In addition, a USB based receiver and computer software were employed for proof-of concept tests of the developed biodevices. Operation of bench-top prototypes was demonstrated in buffers containing different concentrations of the analytes, showcasing that the variation in response of both carbohydrate and oxygen biosensors could be monitored wirelessly in real-time as analyte concentrations in buffers were changed, using only an enzymatic fuel cell as a power supply. PMID:25310190

Self-powered wireless carbohydrate/oxygen sensitive biodevice based on radio signal transmission.

PubMed

Falk, Magnus; Alcalde, Miguel; Bartlett, Philip N; De Lacey, Antonio L; Gorton, Lo; Gutierrez-Sanchez, Cristina; Haddad, Raoudha; Kilburn, Jeremy; Leech, Dónal; Ludwig, Roland; Magner, Edmond; Mate, Diana M; Conghaile, Peter Ó; Ortiz, Roberto; Pita, Marcos; Pöller, Sascha; Ruzgas, Tautgirdas; Salaj-Kosla, Urszula; Schuhmann, Wolfgang; Sebelius, Fredrik; Shao, Minling; Stoica, Leonard; Sygmund, Cristoph; Tilly, Jonas; Toscano, Miguel D; Vivekananthan, Jeevanthi; Wright, Emma; Shleev, Sergey

2014-01-01

Here for the first time, we detail self-contained (wireless and self-powered) biodevices with wireless signal transmission. Specifically, we demonstrate the operation of self-sustained carbohydrate and oxygen sensitive biodevices, consisting of a wireless electronic unit, radio transmitter and separate sensing bioelectrodes, supplied with electrical energy from a combined multi-enzyme fuel cell generating sufficient current at required voltage to power the electronics. A carbohydrate/oxygen enzymatic fuel cell was assembled by comparing the performance of a range of different bioelectrodes followed by selection of the most suitable, stable combination. Carbohydrates (viz. lactose for the demonstration) and oxygen were also chosen as bioanalytes, being important biomarkers, to demonstrate the operation of the self-contained biosensing device, employing enzyme-modified bioelectrodes to enable the actual sensing. A wireless electronic unit, consisting of a micropotentiostat, an energy harvesting module (voltage amplifier together with a capacitor), and a radio microchip, were designed to enable the biofuel cell to be used as a power supply for managing the sensing devices and for wireless data transmission. The electronic system used required current and voltages greater than 44 µA and 0.57 V, respectively to operate; which the biofuel cell was capable of providing, when placed in a carbohydrate and oxygen containing buffer. In addition, a USB based receiver and computer software were employed for proof-of concept tests of the developed biodevices. Operation of bench-top prototypes was demonstrated in buffers containing different concentrations of the analytes, showcasing that the variation in response of both carbohydrate and oxygen biosensors could be monitored wirelessly in real-time as analyte concentrations in buffers were changed, using only an enzymatic fuel cell as a power supply.

Tailoring Oxygen Sensitivity with Halide Substitution in Difluoroboron Dibenzoylmethane Polylactide Materials

PubMed Central

DeRosa, Christopher A.; Kerr, Caroline; Fan, Ziyi; Kolpaczynska, Milena; Mathew, Alexander S.; Evans, Ruffin E.; Zhang, Guoqing; Fraser, Cassandra L.

2015-01-01

The dual-emissive properties of solid-state difluoroboron β-diketonate-poly(lactic acid) (BF2bdkPLA) materials have been utilized for biological oxygen sensing. In this work, BF2dbm(X)PLA materials were synthesized, where X = H, F, Cl, Br, and I. The effects of changing the halide substituent and PLA polymer chain length on the optical properties in dilute CH2Cl2 solutions and solid-state polymer films were studied. These luminescent materials show fluorescence, phosphorescence, and lifetime tunability on the basis of molecular weight, as well as lifetime modulation via the halide substituent. Short BF2dbm(Br)PLA (6.0 kDa) and both short and long BF2dbm(I)PLA polymers (6.0 or 20.3 kDa) have fluorescence and intense phosphorescence ideal for ratiometric oxygen sensing. The lighter halide-dye polymers with hydrogen, fluorine, and chlorine substitution have longer phosphorescence lifetimes and can be utilized as ultrasensitive oxygen sensors. Photostability was also analyzed for the polymer films. PMID:26480236

Intensive Care Physiotherapy during Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome.

PubMed

Munshi, Laveena; Kobayashi, Tadahiro; DeBacker, Julian; Doobay, Ravi; Telesnicki, Teagan; Lo, Vincent; Cote, Nathalie; Cypel, Marcelo; Keshavjee, Shaf; Ferguson, Niall D; Fan, Eddy

2017-02-01

There are limited data on physiotherapy during extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS). We sought to characterize physiotherapy delivered to patients with ARDS supported with ECMO, as well as to evaluate the association of this therapeutic modality with mortality. We conducted a retrospective cohort study of all adult patients with ARDS supported with ECMO at our institution between 2010 and 2015. The highest level of daily activity while on ECMO was coded using the ICU Mobility Scale. Through multivariable logistic regression, we evaluated the association between intensive care unit (ICU) physiotherapy and ICU mortality. In an exploratory univariate analysis, we also evaluated factors associated with a higher intensity of ICU rehabilitation while on ECMO. Of 107 patients who underwent ECMO, 61 (57%) had ARDS requiring venovenous ECMO. The ICU physiotherapy team was consulted for 82% (n = 50) of patients. Thirty-nine percent (n = 18) of these patients achieved an activity level of 2 or higher (active exercises in bed), and 17% (n = 8) achieved an activity level 4 or higher (actively sitting over the side of the bed). In an exploratory analysis, consultation with the ICU physiotherapy team was associated with decreased ICU mortality (odds ratio, 0.19; 95% confidence interval, 0.04-0.98). In univariate analysis, severity-of-illness factors differentiated higher-intensity and lower-intensity physiotherapy. Physiotherapy during ECMO is feasible and safe when performed by an experienced team and executed in stages. Although our study suggests an association with improved ICU mortality, future research is needed to identify potential barriers, optimal timing, dosage, and safety profile.

Oxygen sensing for industrial safety - evolution and new approaches.

PubMed

Willett, Martin

2014-03-27

The requirement for the detection of oxygen in industrial safety applications has historically been met by electrochemical technologies based on the consumption of metal anodes. Products using this approach have been technically and commercially successful for more than three decades. However, a combination of new requirements is driving the development of alternative approaches offering fresh opportunities and challenges. This paper reviews some key aspects in the evolution of consumable anode products and highlights recent developments in alternative technologies aimed at meeting current and anticipated future needs in this important application.

Effects of different concentrations of isoflurane pretreatment on respiratory mechanics, oxygenation and hemodynamics in LPS-induced acute respiratory distress syndrome model of juvenile piglets.

PubMed

Fu, Haibin; Sun, Minli; Miao, Changhong

2015-01-01

This study was prospectively designed to investigate the effects of different concentrations of isoflurane (ISO) pretreatment on respiratory mechanics, oxygenation, and hemodynamics in lipopolysaccharide (LPS)-induced acute respiratory distress syndrome (ARDS) model of juvenile piglets. Twenty-four piglets (9-14 kg, 5-6 weeks old) were randomly assigned to four groups (n = 6): LPS group, which was injected with LPS (20 μg/kg) to induce ARDS; 0.5 ISO-LPS, 1.0 ISO-LPS, and 1.3 ISO-LPS groups, which were pretreated with 0.5, 1.0, and 1.3 minimum alveolar concentrations (MAC) ISO for 30 min before immediate LPS infusion, respectively. After establishment of ARDS, respiratory mechanism, oxygenation and hemodynamics parameters were measured at baseline, and 0, 1, 2, 3, and 4 hours after induction of ARDS. After induction of ARDS, there were increases in alveolar-arterial oxygen difference (A-aDO2), oxygenation index (OI), mean airway pressure (MAP), dead space-to-tidal volume ratio, heart rate (HR), dP/dtmax, extravascular lung water index, pulmonary vascular permeability index, and PaCO2, and decreases in PaO2/FIO2, respiratory rate (RR), dynamic lung compliance (Cdyn), mean arterial blood pressure (MABP) and systemic vascular resistance (SVR) compared with baseline (P(time) < 0.05). Pretreatment with 1.0 and 1.3 MAC ISO alleviated changes in dP/dtmax and PaCO2 at ARDS 0-2 hours, SVR at 0-3 hours, PaO2/FIO2, RR, and MABP at 1-2 hours, HR at 2-3 hours, A-aDO2 at 3-4 hours, and OI at 4 hours (P(group) < 0.05). Pretreatment with 1.0 and 1.3 MAC ISO had protective effects on respiratory mechanics, oxygenation, and hemodynamics in piglets with LPS-induced ARDS.

[Effect of antihypoxants on the consumption of oxygen in animals with traumatic brain injury].

PubMed

Novikov, V E; Ponamareva, N S; Kokhonov, K V

2008-01-01

The effect of drugs on the dynamics of oxygen consumption in experimental animals with traumatic brain injury (TBI) has been measured. It is established that the antihypoxants bemithyl, amtizole, trymeen, and ethomersol in a dose of 25 mg/kg decrease the consumption of oxygen and reduced oxygen demands of tissues in the acute posttraumatic period. These phenomena can play a significant role in the mechanism of the protective action of drugs under conditions of TBI.

Hyperbaric oxygen therapy for Bell's palsy.

PubMed

Holland, N Julian; Bernstein, Jonathan M; Hamilton, John W

2012-02-15

Bell's palsy is an idiopathic, acute unilateral facial weakness that evolves rapidly and is maximal within two days. Moderate ear discomfort, sensitivity to sound and reduced tearing may occur. To assess the effects of hyperbaric oxygen therapy on recovery of facial function in adults with moderate to severe Bell's palsy. We searched the Cochrane Neuromuscular Disease Group Specialized Register (January 2012), CENTRAL (2011, Issue 4), MEDLINE (January 1966 to January 2012), EMBASE (January 1980 to January 2012), CINAHL (1937 to January 2012), AMED (1985 to January 2012), LILACS (January 1982 to January 2012). In addition we made a systematic search for relevant controlled trials in specific hyperbaric literature sources. Randomised controlled trials or quasi-randomised controlled trials of adults (over 16 years of age) undergoing hyperbaric oxygen therapy for moderate to severe Bell's palsy. We considered studies to be of sufficient quality for inclusion in the review only if there was blinding in the assessment of the facial palsy grade. We planned to include studies of HBOT used as adjuvant therapy, or in addition to routine medical therapy (including corticosteroids or antivirals, or both). Both treatment and control groups were to receive the same baseline therapy. HBOT had to be delivered at concentrations greater than or equal to 1.2 ATA in a hyperbaric oxygen chamber as a series of dives of 30 to 120 minutes. Two reviewers independently assessed eligibility and study quality and extracted data. We contacted study authors for additional information. Our searches found no randomised controlled trials or quasi-randomised controlled trials that met the eligibility criteria for this review.There is very low quality evidence from one randomised trial involving 79 participants with acute Bell's palsy, but this study was excluded as the outcome assessor was not blinded to treatment allocation and thus did not meet pre-defined eligibility criteria. The trial compared

A flexible transcutaneous oxygen sensor using polymer membranes.

PubMed

Kudo, Hiroyuki; Iguchi, Shigehito; Yamada, Takua; Kawase, Tatsuya; Saito, Hirokazu; Otsuka, Kimio; Mitsubayashi, Kohji

2007-02-01

A wearable and flexible oxygen sensor for transcutaneous blood gas monitoring was fabricated and tested. The sensor has a laminar film-like structure, which was fabricated by pouching KCl electrolyte solution by both non-permeable (metal weldable) sheet and gas-permeable membrane with Pt- and Ag/AgCl-electrodes patterned using microfabrication process. The electrolyte solution was fixed only by heat-sealing the edges of the weldable membranes without any chemical adhesives. The wearable oxygen sensor (thickness: 84 mum) was applied to the electrochemical measurement with a constant potential of -600 mV vs. Ag/AgCl, thus obtaining the calibration range to dissolved oxygen (DO) from 0.0 to 7.0 mg/l with a correlation coefficient of 0.998 and the quick response time (53.4 s to 90% of a steady-state current), which operate similarly to a commercially available oxygen electrode. The sensor was also utilized to transcutaneous oxygen monitoring for healthy human subject. The sensing region of the wearable oxygen sensor was attached onto the forearm-skin surface of the subject inhaling various concentrations of oxygen. As a result of physiological application, the output current was varied from -6.2 microA to -7.8 microA within 2 min when the concentration of inhaling oxygen was changed from atmospheric air to 60% oxygen. Thus, the transcutaneous oxygen was successfully monitored without any inconveniences such as skin inflammation, etc.

Protective Role for Antioxidants in Acute Kidney Disease

PubMed Central

Dennis, Joanne M.; Witting, Paul K.

2017-01-01

Acute kidney injury causes significant morbidity and mortality in the community and clinic. Various pathologies, including renal and cardiovascular disease, traumatic injury/rhabdomyolysis, sepsis, and nephrotoxicity, that cause acute kidney injury (AKI), induce general or regional decreases in renal blood flow. The ensuing renal hypoxia and ischemia promotes the formation of reactive oxygen species (ROS) such as superoxide radical anions, peroxides, and hydroxyl radicals, that can oxidatively damage biomolecules and membranes, and affect organelle function and induce renal tubule cell injury, inflammation, and vascular dysfunction. Acute kidney injury is associated with increased oxidative damage, and various endogenous and synthetic antioxidants that mitigate source and derived oxidants are beneficial in cell-based and animal studies. However, the benefit of synthetic antioxidant supplementation in human acute kidney injury and renal disease remains to be realized. The endogenous low-molecular weight, non-proteinaceous antioxidant, ascorbate (vitamin C), is a promising therapeutic in human renal injury in critical illness and nephrotoxicity. Ascorbate may exert significant protection by reducing reactive oxygen species and renal oxidative damage via its antioxidant activity, and/or by its non-antioxidant functions in maintaining hydroxylase and monooxygenase enzymes, and endothelium and vascular function. Ascorbate supplementation may be particularly important in renal injury patients with low vitamin C status. PMID:28686196

Microvascular oxygen consumption during sickle cell pain crisis.

PubMed

Rowley, Carol A; Ikeda, Allison K; Seidel, Miles; Anaebere, Tiffany C; Antalek, Matthew D; Seamon, Catherine; Conrey, Anna K; Mendelsohn, Laurel; Nichols, James; Gorbach, Alexander M; Kato, Gregory J; Ackerman, Hans

2014-05-15

Sickle cell disease is an inherited blood disorder characterized by chronic hemolytic anemia and episodic vaso-occlusive pain crises. Vaso-occlusion occurs when deoxygenated hemoglobin S polymerizes and erythrocytes sickle and adhere in the microvasculature, a process dependent on the concentration of hemoglobin S and the rate of deoxygenation, among other factors. We measured oxygen consumption in the thenar eminence during brachial artery occlusion in sickle cell patients and healthy individuals. Microvascular oxygen consumption was greater in sickle cell patients than in healthy individuals (median [interquartile range]; sickle cell: 0.91 [0.75-1.07] vs healthy: 0.75 [0.62-0.94] -ΔHbO2/min, P < .05) and was elevated further during acute pain crisis (crisis: 1.10 [0.78-1.30] vs recovered: 0.88 [0.76-1.03] -ΔHbO2/min, P < .05). Increased microvascular oxygen consumption during pain crisis could affect the local oxygen saturation of hemoglobin when oxygen delivery is limiting. Identifying the mechanisms of elevated oxygen consumption during pain crisis might lead to the development of new therapeutic interventions. This trial was registered at www.clinicaltrials.gov as #NCT01568710.

Performance Evaluation of an Oxygen Sensor as a Function of the Samaria Doped Ceria Film Thickness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T

The current demand in the automobile industry is in the control of air-fuel mixture in the combustion engine of automobiles. Oxygen partial pressure can be used as an input parameter for regulating or controlling systems in order to optimize the combustion process. Our goal is to identify and optimize the material system that would potentially function as the active sensing material for such a device that monitors oxygen partial pressure in these systems. We have used thin film samaria doped ceria (SDC) as the sensing material for the sensor operation, exploiting the fact that at high temperatures, oxygen vacancies generatedmore » due to samarium doping act as conducting medium for oxygen ions which hop through the vacancies from one side to the other contributing to an electrical signal. We have recently established that 6 atom % Sm doping in ceria films has optimum conductivity. Based on this observation, we have studied the variation in the overall conductivity of 6 atom % samaria doped ceria thin films as a function of thickness in the range of 50 nm to 300 nm at a fixed bias voltage of 2 volts. A direct proportionality in the increase in the overall conductivity is observed with the increase in sensing film thickness. For a range of oxygen pressure values from 1 mTorr to 100 Torr, a tolerable hysteresis error, good dynamic response and a response time of less than 10 seconds was observed« less

Mitochondrial complex I deactivation is related to superoxide production in acute hypoxia.

PubMed

Hernansanz-Agustín, Pablo; Ramos, Elena; Navarro, Elisa; Parada, Esther; Sánchez-López, Nuria; Peláez-Aguado, Laura; Cabrera-García, J Daniel; Tello, Daniel; Buendia, Izaskun; Marina, Anabel; Egea, Javier; López, Manuela G; Bogdanova, Anna; Martínez-Ruiz, Antonio

2017-08-01

Mitochondria use oxygen as the final acceptor of the respiratory chain, but its incomplete reduction can also produce reactive oxygen species (ROS), especially superoxide. Acute hypoxia produces a superoxide burst in different cell types, but the triggering mechanism is still unknown. Herein, we show that complex I is involved in this superoxide burst under acute hypoxia in endothelial cells. We have also studied the possible mechanisms by which complex I could be involved in this burst, discarding reverse electron transport in complex I and the implication of PTEN-induced putative kinase 1 (PINK1). We show that complex I transition from the active to 'deactive' form is enhanced by acute hypoxia in endothelial cells and brain tissue, and we suggest that it can trigger ROS production through its Na + /H + antiporter activity. These results highlight the role of complex I as a key actor in redox signalling in acute hypoxia. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Using sense-making theory to aid understanding of the recognition, assessment and management of pain in patients with dementia in acute hospital settings.

PubMed

Dowding, Dawn; Lichtner, Valentina; Allcock, Nick; Briggs, Michelle; James, Kirstin; Keady, John; Lasrado, Reena; Sampson, Elizabeth L; Swarbrick, Caroline; José Closs, S

2016-01-01

The recognition, assessment and management of pain in hospital settings is suboptimal, and is a particular challenge in patients with dementia. The existing process guiding pain assessment and management in clinical settings is based on the assumption that nurses follow a sequential linear approach to decision making. In this paper we re-evaluate this theoretical assumption drawing on findings from a study of pain recognition, assessment and management in patients with dementia. To provide a revised conceptual model of pain recognition, assessment and management based on sense-making theories of decision making. The research we refer to is an exploratory ethnographic study using nested case sites. Patients with dementia (n=31) were the unit of data collection, nested in 11 wards (vascular, continuing care, stroke rehabilitation, orthopaedic, acute medicine, care of the elderly, elective and emergency surgery), located in four NHS hospital organizations in the UK. Data consisted of observations of patients at bedside (170h in total); observations of the context of care; audits of patient hospital records; documentary analysis of artefacts; semi-structured interviews (n=56) and informal open conversations with staff and carers (family members). Existing conceptualizations of pain recognition, assessment and management do not fully explain how the decision process occurs in clinical practice. Our research indicates that pain recognition, assessment and management is not an individual cognitive activity; rather it is carried out by groups of individuals over time and within a specific organizational culture or climate, which influences both health care professional and patient behaviour. We propose a revised theoretical model of decision making related to pain assessment and management for patients with dementia based on theories of sense-making, which is reflective of the reality of clinical decision making in acute hospital wards. The revised model recognizes the

Hyperbaric oxygen therapy as treatment for bilateral arm compartment syndrome after CrossFit: case report and literature review.

PubMed

Mendes, Adriano Fernando; Neto, José da Mota; Heringer, Erica Maciel; de Simoni, Leandro Furtado; Pires, Diego Demolinari; Labronici, Pedro José

2018-01-01

CrossFit is a physical fitness program characterized by high-intensity workouts that can be associated with serious injury. Acute compartment syndrome in the upper limbs is a rare occurrence. It may occur after intense physical exercise, and its usual treatment is surgical. Hyperbaric oxygen therapy is a treatment described as adjunctive in cases of compartmental syndrome. We describe the case of a CrossFit practitioner who, after intense training, developed progressive symptoms of rhabdomyolysis and acute bilateral arm compartment syndrome, who was successfully treated with hyperbaric oxygen therapy and required no fasciotomy as surgical treatment. Acute compartment syndrome in the arms after intense physical exercise is a rare occurrence that should be suspected by practitioners of physical activity experiencing intense, disproportionate and progressive pain. In the case presented, hyperbaric oxygen therapy was successfully used in the treatment of the disorder, with satisfactory progress, and without the need for a surgical fasciotomy as therapy. Copyright© Undersea and Hyperbaric Medical Society.

Oxygen consumption, oxygen cost, heart rate, and perceived effort during split-belt treadmill walking in young healthy adults.

PubMed

Roper, Jaimie A; Stegemöller, Elizabeth L; Tillman, Mark D; Hass, Chris J

2013-03-01

During split-belt treadmill walking the speed of the treadmill under one limb is faster than the belt under the contralateral limb. This unique intervention has shown evidence of acutely improving gait impairments in individuals with neurologic impairment such as stroke and Parkinson's disease. However, oxygen use, heart rate and perceived effort associated with split-belt treadmill walking are unknown and may limit the utility of this locomotor intervention. To better understand the intensity of this new intervention, this study was undertaken to examine the oxygen consumption, oxygen cost, heart rate, and rating of perceived exertion associated with split-belt treadmill walking in young healthy adults. Fifteen participants completed three sessions of treadmill walking: slow speed with belts tied, fast speed with belts tied, and split-belt walking with one leg walking at the fast speed and one leg walking at the slow speed. Oxygen consumption, heart rate, and rating of perceived exertion were collected during each walking condition and oxygen cost was calculated. Results revealed that oxygen consumption, heart rate, and perceived effort associated with split-belt walking were higher than slow treadmill walking, but only oxygen consumption was significantly lower during both split-belt walking than fast treadmill walking. Oxygen cost associated with slow treadmill walking was significantly higher than fast treadmill walking. These findings have implications for using split-belt treadmill walking as a rehabilitation tool as the cost associated with split-belt treadmill walking may not be higher or potentially more detrimental than that associated with previously used treadmill training rehabilitation strategies.

Device and method for determining oxygen concentration and pressure in gases

DOEpatents

Ayers, M.R.; Hunt, A.J.

1999-03-23

Disclosed are oxygen concentration and/or pressure sensing devices and methods which incorporate photoluminescent silica aerogels. Disclosed sensors include a light proof housing for holding the photoluminescent aerogel, a source of excitation radiation (e.g., a UV source), a detector for detecting radiation emitted by the aerogel, a system for delivering a sample gas to the aerogel, and a thermocouple. Also disclosed are water resistant oxygen sensors having a photoluminescent aerogel coated with a hydrophobic material. 6 figs.

Device and method for determining oxygen concentration and pressure in gases

DOEpatents

Ayers, Michael R.; Hunt, Arlon J.

1999-01-01

Disclosed are oxygen concentration and/or pressure sensing devices and methods which incorporate photoluminescent silica aerogels. Disclosed sensors include a light proof housing for holding the photoluminescent aerogel, a source of excitation radiation (e.g., a UV source), a detector for detecting radiation emitted by the aerogel, a system for delivering a sample gas to the aerogel, and a thermocouple. Also disclosed are water resistant oxygen sensors having a photoluminescent aerogel coated with a hydrophobic material.

Hydrogel-Based Fluorescent Dual pH and Oxygen Sensors Loaded in 96-Well Plates for High-Throughput Cell Metabolism Studies.

PubMed

Wu, Shanshan; Wu, Siying; Yi, Zheyuan; Zeng, Fei; Wu, Weizhen; Qiao, Yuan; Zhao, Xingzhong; Cheng, Xing; Tian, Yanqing

2018-02-13

In this study, we developed fluorescent dual pH and oxygen sensors loaded in multi-well plates for in-situ and high-throughput monitoring of oxygen respiration and extracellular acidification during microbial cell growth for understanding metabolism. Biocompatible PHEMA-co-PAM materials were used as the hydrogel matrix. A polymerizable oxygen probe (OS2) derived from PtTFPP and a polymerizable pH probe (S2) derived from fluorescein were chemically conjugated into the matrix to solve the problem of the probe leaching from the matrix. Gels were allowed to cure directly on the bottom of 96-well plates at room-temperature via redox polymerization. The influence of matrix's composition on the sensing behaviors was investigated to optimize hydrogels with enough robustness for repeatable use with good sensitivity. Responses of the dual sensing hydrogels to dissolved oxygen (DO) and pH were studied. These dual oxygen-pH sensing plates were successfully used for microbial cell-based screening assays, which are based on the measurement of fluorescence intensity changes induced by cellular oxygen consumption and pH changes during microbial growth. This method may provide a real-time monitoring of cellular respiration, acidification, and a rapid kinetic assessment of multiple samples for cell viability as well as high-throughput drug screening. All of these assays can be carried out by a conventional plate reader.

[Use of antihypoxants in the acute period of myocardial infarction].

PubMed

Semigolovskiĭ, N Iu

1998-01-01

A total of 620 patients with acute myocardial infarction were followed up in order to assess the efficacy of antihypoxants as a component of intensive care. 385 of these patients, divided into groups of 20-40 subjects, were administered one of 12 antihypoxants or sessions of hyperbaric oxygenation during the acute period of the disease, the rest were treated traditionally. Analysis of clinical, laboratory, and prognostic values showed the highest protective effect of amtizol, lithium hydroxybutyrate, piracetam, and ubiquinone. Cytochrome C, riboxine, mildronate, and olifen were somewhat less active, and solcoseryl, bemitil, trimethasidine, and aspisol were the least effective. The protective potentialities of standard sessions of hyperbaric oxygenation were virtually null. The author proposes a parameter D, reflecting the difference between actual and predicted mortality, and the rating (score) system for assessing the routine laboratory diagnostic tests to be used together with the known criteria for evaluation of the protective effects of antihypoxants in patients with acute myocardial infarction.

Bladder urine oxygen tension for assessing renal medullary oxygenation in rabbits: experimental and modeling studies

PubMed Central

Sgouralis, Ioannis; Kett, Michelle M.; Ow, Connie P. C.; Abdelkader, Amany; Layton, Anita T.; Gardiner, Bruce S.; Smith, David W.; Lankadeva, Yugeesh R.

2016-01-01

Oxygen tension (Po2) of urine in the bladder could be used to monitor risk of acute kidney injury if it varies with medullary Po2. Therefore, we examined this relationship and characterized oxygen diffusion across walls of the ureter and bladder in anesthetized rabbits. A computational model was then developed to predict medullary Po2 from bladder urine Po2. Both intravenous infusion of [Phe2,Ile3,Orn8]-vasopressin and infusion of NG-nitro-l-arginine reduced urinary Po2 and medullary Po2 (8–17%), yet had opposite effects on renal blood flow and urine flow. Changes in bladder urine Po2 during these stimuli correlated strongly with changes in medullary Po2 (within-rabbit r2 = 0.87–0.90). Differences in the Po2 of saline infused into the ureter close to the kidney could be detected in the bladder, although this was diminished at lesser ureteric flow. Diffusion of oxygen across the wall of the bladder was very slow, so it was not considered in the computational model. The model predicts Po2 in the pelvic ureter (presumed to reflect medullary Po2) from known values of bladder urine Po2, urine flow, and arterial Po2. Simulations suggest that, across a physiological range of urine flow in anesthetized rabbits (0.1–0.5 ml/min for a single kidney), a change in bladder urine Po2 explains 10–50% of the change in pelvic urine/medullary Po2. Thus, it is possible to infer changes in medullary Po2 from changes in urinary Po2, so urinary Po2 may have utility as a real-time biomarker of risk of acute kidney injury. PMID:27385734

C-MEMS for bio-sensing applications

NASA Astrophysics Data System (ADS)

Song, Yin; Agrawal, Richa; Wang, Chunlei

2015-05-01

Developing highly sensitive, selective, and reproducible miniaturized bio-sensing platforms require reliable biointerface which should be compatible with microfabrication techniques. In this study, we have fabricated pyrolyzed carbon arrays with high surface area as a bio-sensing electrode, and developed the surface functionalization methods to increase biomolecules immobilization efficiency and further understand electrochemical phenomena at biointerfaces. The carbon microelectrode arrays with high aspect ratio have been fabricated by carbon microelectromechanical systems (C-MEMS) and nanomaterials such as graphene have been integrated to further increase surface area. To achieve the efficient covalent immobilization of biomolecules, various oxidation and reduction functionalization methods have been investigated. The oxidation treatment in this study includes vacuum ultraviolet, electrochemical activation, UV/Ozone and oxygen RIE. The reduction treatment includes direct amination and diazonium grafting. The developed bio-sensing platform was then applied for several applications, such as: DNA sensor; H2O2 sensor; aptamer sensor and HIV sensor.

ACUTE BEHAVIORAL TOXICITY OF SULFOLANE: INFLUENCE OF HYPOTHERMIA

EPA Science Inventory

Sulfolane is a solvent which produces hypothermia and decreased oxygen consumption following acute exposure. In the present experiment, the author investigated effects of sulfolane on a behavioral measure of toxicity at ambient temperatures which would either prevent or facilitat...

Noncollinear magnetic order induced by Dzyaloshinskii-Moriya interaction in oxygen-assisted Pt nanojunctions

NASA Astrophysics Data System (ADS)

Yuan, J. R.; Yan, X. H.; Xiao, Y.; Guo, Y. D.; Dai, C. J.

2016-11-01

Motivated by recent measurement of the magnetism and conductance of the oxygen-assisted Pt nanojunctions, we performed first principle calculations of the magnetic order and electronic transport by explicitly including fully relativistic effects. Our results show that the spin alignment is a cycloidal spiral feature attributed to the Dzyaloshinskii-Moriya interaction, which indicates that the observed magnetism in experiments is of noncollinear nature. The oxygen concentration is the responsible for the switching of the rotational sense of the spiral magnetic order found in oxygen-assisted Pt nanojunctions. Furthermore, the magnetic moments and magnetoresistances vary with oxygen concentration in the chain, which can be used to tune the magnetism and magnetotransport. The oxygen-assisted Pt nanojunctions offer a possibility for spintronic applications in magnetic memory and quantum devices.

Singlet oxygen-based electrosensing by molecular photosensitizers

NASA Astrophysics Data System (ADS)

Trashin, Stanislav; Rahemi, Vanoushe; Ramji, Karpagavalli; Neven, Liselotte; Gorun, Sergiu M.; de Wael, Karolien

2017-07-01

Enzyme-based electrochemical biosensors are an inspiration for the development of (bio)analytical techniques. However, the instability and reproducibility of the reactivity of enzymes, combined with the need for chemical reagents for sensing remain challenges for the construction of useful devices. Here we present a sensing strategy inspired by the advantages of enzymes and photoelectrochemical sensing, namely the integration of aerobic photocatalysis and electrochemical analysis. The photosensitizer, a bioinspired perfluorinated Zn phthalocyanine, generates singlet-oxygen from air under visible light illumination and oxidizes analytes, yielding electrochemically-detectable products while resisting the oxidizing species it produces. Compared with enzymatic detection methods, the proposed strategy uses air instead of internally added reactive reagents, features intrinsic baseline correction via on/off light switching and shows C-F bonds-type enhanced stability. It also affords selectivity imparted by the catalytic process and nano-level detection, such as 20 nM amoxicillin in μl sample volumes.

Singlet oxygen-based electrosensing by molecular photosensitizers

PubMed Central

Trashin, Stanislav; Rahemi, Vanoushe; Ramji, Karpagavalli; Neven, Liselotte; Gorun, Sergiu M.; De Wael, Karolien

2017-01-01

Enzyme-based electrochemical biosensors are an inspiration for the development of (bio)analytical techniques. However, the instability and reproducibility of the reactivity of enzymes, combined with the need for chemical reagents for sensing remain challenges for the construction of useful devices. Here we present a sensing strategy inspired by the advantages of enzymes and photoelectrochemical sensing, namely the integration of aerobic photocatalysis and electrochemical analysis. The photosensitizer, a bioinspired perfluorinated Zn phthalocyanine, generates singlet-oxygen from air under visible light illumination and oxidizes analytes, yielding electrochemically-detectable products while resisting the oxidizing species it produces. Compared with enzymatic detection methods, the proposed strategy uses air instead of internally added reactive reagents, features intrinsic baseline correction via on/off light switching and shows C-F bonds-type enhanced stability. It also affords selectivity imparted by the catalytic process and nano-level detection, such as 20 nM amoxicillin in μl sample volumes.

Acute otitis media: making sense of recent guidelines on antimicrobial treatment.

PubMed

Pichichero, Michael E; Casey, Janet R

2005-04-01

High-dose amoxicillin (80 to 90 mg/kg/d divided twice daily) remains the drug of choice for treatment of acute otitis media despite increasing antimicrobial resistance. For persistent or recurrent acute otitis media, guidelines recommend high-dose amoxicillin/clavulanate (90/6.4 mg/kg/d), cefdinir, cefprozil, cefpodoxime, cefuroxime, or ceftriaxone. Increasing the dose of amoxicillin does not cover infection with beta-lactamase-producing pathogens; add the beta-lactamase inhibitor clavulanate to amoxicillin, or choose a cephalosporin with good activity against S pneumoniae and good beta-lactamase stability. Key factors for enhancing compliance are taste of suspension, dosing frequency, and duration of therapy.

Sensing hypoxia by mitochondria: a unifying hypothesis involving S-nitrosation.

PubMed

Ullrich, Volker; Schildknecht, Stefan

2014-01-10

Sudden hypoxia requires a rapid response in tissues with high energy demand. Mitochondria are rapid sensors for a lack of oxygen, but no consistent mechanism for the sensing process and the subsequent counter-regulation has been described. In the present hypothesis review, we suggest an oxygen-sensing mechanism by mitochondria that is initiated at low oxygen tension by electrons from the respiratory chain, leading to the reduction of intracellular nitrite to nitric oxide ((•)NO) that would subsequently compete with oxygen for binding to cytochrome c oxidase. This allows superoxide ((•)O2(-)) formation in hypoxic areas, leading to S-nitrosation and the inhibition of mitochondrial Krebs cycle enzymes. With more formation of (•)O2(-), peroxynitrite is generated and known to damage the connection between the mitochondrial matrix and the outer membrane. A fundamental question on a regulatory mechanism is its reversibility. Readmission of oxygen and opening of the mitochondrial KATP-channel would allow electrons from glycerol-3-phosphate to selectively reduce the ubiquinone pool to generate (•)O2(-) at both sides of the inner mitochondrial membrane. On the cytosolic side, superoxide is dismutated and will support H2O2/Fe(2+)-dependent transcription processes and on the mitochondrial matrix side, it could lead to the one-electron reduction and reactivation of S-nitrosated proteins. It remains to be elucidated up to which stage the herein proposed silencing of mitochondria remains reversible and when irreversible changes that ultimately lead to classical reperfusion injury are initiated.

Benefits of 21% Oxygen Compared with 100% Oxygen for Delivery of Isoflurane to Mice (Mus musculus) and Rats (Rattus norvegicus)

PubMed Central

Wilding, Laura A; Hampel, Joe A; Khoury, Basma M; Kang, Stacey; Machado‑Aranda, David; Raghavendran, Krishnan; Nemzek, Jean A

2017-01-01

At research institutions, isoflurane delivered by precision vaporizer to a face mask is the standard for rodent surgery and for procedures with durations that exceed a few minutes. Pure oxygen is often used as the carrier gas for isoflurane anesthesia, despite documented complications from long-term 100% oxygen use in humans and known occupational safety risks. We therefore examined the effect of anesthetic delivery gas on physiologic variables in mice and rats. Rodents were anesthetized for 60 min with isoflurane delivered in either 21% or 100% oxygen by means of a nose cone. We noted no difference between carrier gasses in physiologic variables in mice, including body temperature, respiratory rate, mean arterial pressure, surgical recovery time, pH, or PaCO2.However, blood gas analysis revealed evidence of a ventilation–perfusion mismatch in the 100% oxygen group. Pressure–volume hysteresis and histomorphometric analyses confirmed the presence of increased atelectasis in mice that received 100% oxygen. Unlike mice, rats that received isoflurane in 100% oxygen had acute respiratory acidosis and elevated mean arterial pressure, but atelectasis was similar between carrier gasses. Our data suggest that both 100% and 21% oxygen are acceptable for the delivery of isoflurane to mice. However, mice anesthetized for studies focused on lung physiology or architecture would benefit from the delivery of isoflurane in 21% oxygen to reduce absorption atelectasis and the potential associated downstream inflammatory effects. For rats, delivery of isoflurane in 21% and 100% oxygen both caused perturbations in physiologic variables, and choosing a carrier gas is not straightforward. PMID:28315643

Photoacoustic lifetime imaging for direct in vivo tissue oxygen monitoring

PubMed Central

Shao, Qi; Ashkenazi, Shai

2015-01-01

Abstract. Measuring the partial pressure of oxygen (pO2) in tissue may provide physicians with essential information about the physiological state of tissue. However, currently available methods for measuring or imaging tissue pO2 have significant limitations, preventing them from being widely used in clinics. Recently, we have reported a direct and noninvasive in vivo imaging modality based on the photoacoustic lifetime which overcomes certain drawbacks of the existing methods. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflecting the spatial and temporal distributions of tissue oxygen. Here, we present two studies which apply photoacoustic lifetime imaging (PALI) to monitor changes of tissue oxygen induced by external modulations. The first study modulates tissue oxygen by controlling the percentage of oxygen a normal mouse inhales. We demonstrate that PALI is able to reflect the change in oxygen level with respect to normal, oxygen-rich, and oxygen-poor breathing conditions. The second study involves an acute ischemia model using a thin thread tied around the hindlimb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of tissue pO2 and recovery from hypoxia due to reperfusion were tracked and observed by PALI. PMID:25748857

Inflammation in acute and chronic pancreatitis.

PubMed

Habtezion, Aida

2015-09-01

This report reviews recent animal model and human studies associated with inflammatory responses in acute and chronic pancreatitis. Animal model and limited human acute and chronic pancreatitis studies unravel the dynamic nature of the inflammatory processes and the ability of the immune cells to sense danger and environmental signals. In acute pancreatitis, such molecules include pathogen-associated molecular pattern recognition receptors such as toll-like receptors, and the more recently appreciated damage-associated molecular pattern molecules or 'alarmin' high mobility group box 1 and IL-33. In chronic pancreatitis, a recent understanding of a critical role for macrophage-pancreatic stellate cell interaction offers a potential targetable pathway that can alter fibrogenesis. Microbiome research in pancreatitis is a new field gaining interest but will require further investigation. Immune cell contribution to the pathogenesis of acute and chronic pancreatitis is gaining more appreciation and further understanding in immune signaling presents potential therapeutic targets that can alter disease progression.

A robust and reliable optical trace oxygen sensor

NASA Astrophysics Data System (ADS)

McDowell, G. R.; Holmes-Smith, A. S.; Uttamlal, M.; Mitchell, C.; Shannon, P. H.

2017-05-01

In applications of nitrogen (N2) generation, industrial gas manufacturing and food packaging there is a need to ensure oxygen (O2) is absent from the environment, even at the lowest concentration levels. Therefore, there has been an increased growth in the development of trace O2 parts per million (ppm) sensors over the past decade to detect and quantify the concentration of molecular O2 in the environment whether it be dissolved or gaseous O2. The majority of commercially available trace O2 sensors are based on electrochemical, zirconia and paramagnetic technologies. Here, the development of a luminescence-based optical trace O2 sensor is presented. Luminescence-based sensing is now regarded as one of the best techniques for the detection and quantification of O2. This is due to the high detection sensitivity, no O2 is consumed and there are a vast array of luminescent indicators and sensing platforms (polymers) that can be selected to suit the desired application. The sensor will be shown to operate from -30 °C to +60 °C in the 0-1000 ppm and/or 0-1200 μbar partial pressure of oxygen (ppO2) range and is equipped with temperature and pressure compensation. The luminescence non-depleting principle, sensor specifications and miniaturized nature offers an attractive alternative to other sensing technologies and advantages over other luminescence-based O2 ppm sensors.

Subcooled Liquid Oxygen Cryostat for Magneto-Archimedes Particle Separation by Density

NASA Astrophysics Data System (ADS)

Hilton, D. K.; Celik, D.; Van Sciver, S. W.

2008-03-01

An instrument for the separation of particles by density (sorting) is being developed that uses the magneto-archimedes effect in liquid oxygen. With liquid oxygen strongly paramagnetic, the magneto-archimedes effect is an extension of diamagnetic levitation in the sense of increasing the effective buoyancy of a particle. The instrument will be able to separate ensembles of particles from 100 μm to 100 nm in size, and vertically map or mechanically deliver the separated particles. The instrument requires a column of liquid oxygen that is nearly isothermal, free of thermal convection, subcooled to prevent nucleate boiling, and supported against the strong magnetic field used. Thus, the unique cryostat design that meets these requirements is described in the present article. It consists in part of a column of liquid nitrogen below for cooling the liquid oxygen, with the liquid oxygen pressurized by helium gas to prevent nucleate boiling.

A central role for oxygen-sensitive K+ channels and mitochondria in the specialized oxygen-sensing system.

PubMed

Archer, Stephen L; Michelakis, Evangelos D; Thébaud, Bernard; Bonnet, Sebastien; Moudgil, Rohit; Wu, Xi-Chen; Weir, E Kenneth

2006-01-01

Mammals possess a specialized O2-sensing system (SOS), which compensates for encounters with hypoxia that occur during development, disease, and at altitude. Consisting of the resistance pulmonary arteries (PA), ductus arteriosus, carotid body, neuroepithelial body, systemic arteries, fetal adrenomedullary cell and fetoplacental arteries, the SOS optimizes O2-uptake and delivery. Hypoxic pulmonary vasoconstriction (HPV), a vasomotor response of resistance PAs to alveolar hypoxia, optimizes ventilation/perfusion matching and systemic pO2. Though modulated by the endothelium, HPV's core mechanism resides in the smooth muscle cell (SMC). The Redox Theory proposes that HPV results from the coordinated action of a redox sensor (proximal mitochondrial electron transport chain) which generates a diffusible mediator (a reactive O2 species, ROS) that regulates effector proteins (voltage-gated K(v) channels). Hypoxic withdrawal of ROS inhibits K(v)1.5 and K(v)2.1, depolarizes PASMCs, activates voltage-gated Ca2+ channels, increasing Ca2+ influx and causing vasoconstriction. Hypoxia's effect on ROS (decrease vs. increase) and the molecular origins of ROS (mitochondria vs. NADPH oxidase) remains controversial. Distal to this pathway, Rho kinase regulates the contractile apparatus' sensitivity to Ca2+. Also, a role for cADP ribose as a redox-regulated mediator of intracellular Ca2+ release has been proposed. Despite tissue heterogeneity in the SOS's output (vasomotion versus neurosecretion), O2-sensitive K+ channels constitute a conserved effector mechanism. Disorders of the O2-sensing may contribute to diseases, such as pulmonary hypertension.

Acute normobaric hypoxia reduces body temperature in humans.

PubMed

DiPasquale, Dana M; Kolkhorst, Fred W; Buono, Michael J

2015-03-01

Anapyrexia is the regulated decrease in body temperature during acute exposure to hypoxia. This study examined resting rectal temperature (Trec) in adult humans during acute normobaric hypoxia (NH). Ten subjects breathed air consisting of 21% (NN), 14% (NH14), and 12% oxygen (NH12) for 30 min each in thermoneutral conditions while Trec and blood oxygen saturation (Spo2) were measured. Linear regression indicated that Spo2 was progressively lower in NH14 (p=0.0001) and NH12 (p=0.0001) compared to NN, and that Spo2 in NH14 was different than NH12 (p=0.00001). Trec was progressively lower during NH14 (p=0.014) and in NH12 (p=0.0001) compared to NN. The difference in Trec between NH14 and NH12 was also significant (p=0.0287). Spo2 was a significant predictor of Trec such that for every 1% decrease in Spo2, Trec decreased by 0.15°C (p=0.0001). The present study confirmed that, similar to many other species, human adults respond to acute hypoxia exposure by lowering rectal temperature.

Effects of pulmonary static inflation with 50% xenon on oxygen impairment during cardiopulmonary bypass for stanford type A acute aortic dissection

PubMed Central

Jin, Mu; Yang, Yanwei; Pan, Xudong; Lu, Jiakai; Zhang, Zhiquan; Cheng, Weiping

2017-01-01

Abstract Background: The goal of this study was to investigate the effects of pulmonary static inflation with 50% xenon on postoperative oxygen impairment during cardiopulmonary bypass (CPB) for Stanford type A acute aortic dissection (AAD). Methods: This prospective single-center nonrandomized controlled clinical trial included 100 adult patients undergoing surgery for Stanford type A AAD at an academic hospital in China. Fifty subjects underwent pulmonary static inflation with 50% oxygen from January 2013 to January 2014, and 50 underwent inflation with 50% xenon from January 2014 to December 2014. During CPB, the lungs were inflated with either 50% xenon (xenon group) or 50% oxygen (control group) to maintain an airway pressure of 5 cm H2O. The primary outcome was oxygenation index (OI) value after intubation, and 10 minutes and 6 hours after the operation. The second outcome was cytokine and reactive oxygen species levels after intubation and 10 minutes, 6 hours, and 24 hours after the operation. Results: Patients treated with xenon had lower OI levels compared to the control group before surgery (P = 0.002); however, there was no difference in postoperative values between the 2 groups. Following surgery, mean maximal OI values decreased by 18.8% and 33.8%, respectively, in the xenon and control groups. After surgery, the levels of interleukin-6 (IL-6), tumor necrosis factor alpha, and thromboxane B2 decreased by 23.5%, 9.1%, and 30.2%, respectively, in the xenon group, but increased by 10.8%, 26.2%, and 26.4%, respectively, in the control group. Moreover, IL-10 levels increased by 28% in the xenon group and decreased by 7.5% in the control group. There were significant time and treatment-time interaction effects on methane dicarboxylic aldehyde (P = 0.000 and P = 0.050, respectively) and myeloperoxidase (P = 0.000 and P = 0.001 in xenon and control groups, respectively). There was no difference in hospital mortality and 1-year

Oxygen sensation and social feeding mediated by a C. elegans guanylate cyclase homologue.

PubMed

Gray, Jesse M; Karow, David S; Lu, Hang; Chang, Andy J; Chang, Jennifer S; Ellis, Ronald E; Marletta, Michael A; Bargmann, Cornelia I

2004-07-15

Specialized oxygen-sensing cells in the nervous system generate rapid behavioural responses to oxygen. We show here that the nematode Caenorhabditis elegans exhibits a strong behavioural preference for 5-12% oxygen, avoiding higher and lower oxygen levels. 3',5'-cyclic guanosine monophosphate (cGMP) is a common second messenger in sensory transduction and is implicated in oxygen sensation. Avoidance of high oxygen levels by C. elegans requires the sensory cGMP-gated channel tax-2/tax-4 and a specific soluble guanylate cyclase homologue, gcy-35. The GCY-35 haem domain binds molecular oxygen, unlike the haem domains of classical nitric-oxide-regulated guanylate cyclases. GCY-35 and TAX-4 mediate oxygen sensation in four sensory neurons that control a naturally polymorphic social feeding behaviour in C. elegans. Social feeding and related behaviours occur only when oxygen exceeds C. elegans' preferred level, and require gcy-35 activity. Our results suggest that GCY-35 is regulated by molecular oxygen, and that social feeding can be a behavioural strategy for responding to hyperoxic environments.

Remarkably Enhanced Room-Temperature Hydrogen Sensing of SnO₂ Nanoflowers via Vacuum Annealing Treatment.

PubMed

Liu, Gao; Wang, Zhao; Chen, Zihui; Yang, Shulin; Fu, Xingxing; Huang, Rui; Li, Xiaokang; Xiong, Juan; Hu, Yongming; Gu, Haoshuang

2018-03-23

In this work, SnO₂ nanoflowers synthesized by a hydrothermal method were employed as hydrogen sensing materials. The as-synthesized SnO₂ nanoflowers consisted of cuboid-like SnO₂ nanorods with tetragonal structures. A great increase in the relative content of surface-adsorbed oxygen was observed after the vacuum annealing treatment, and this increase could have been due to the increase in surface oxygen vacancies serving as preferential adsorption sites for oxygen species. Annealing treatment resulted in an 8% increase in the specific surface area of the samples. Moreover, the conductivity of the sensors decreased after the annealing treatment, which should be attributed to the increase in electron scattering around the defects and the compensated donor behavior of the oxygen vacancies due to the surface oxygen adsorption. The hydrogen sensors of the annealed samples, compared to those of the unannealed samples, exhibited a much higher sensitivity and faster response rate. The sensor response factor and response rate increased from 27.1% to 80.2% and 0.34%/s to 1.15%/s, respectively. This remarkable enhancement in sensing performance induced by the annealing treatment could be attributed to the larger specific surface areas and higher amount of surface-adsorbed oxygen, which provides a greater reaction space for hydrogen. Moreover, the sensors with annealed SnO₂ nanoflowers also exhibited high selectivity towards hydrogen against CH₄, CO, and ethanol.

Toxin detection using a tyrosinase-coupled oxygen electrode.

PubMed

Smit, M H; Rechnitz, G A

1993-02-15

An enzyme-based "electrochemical canary" is described for the detection of cyanide. The sensing system imitates cyanide's site of toxicity in the mitochondria. The terminal sequence of electron transfer in aerobic respiration is mimicked by mediator coupling of tyrosinase catalysis to an electro-chemical system. An enzyme-coupled oxygen electrode is created which is sensitive to selective poisoning. Biocatalytic reduction of oxygen is promoted by electrochemically supplying tyrosinase with electrons. Thus, ferrocyanide is generated at a cathode and mediates the enzymatic reduction of oxygen to water. An enzyme-dependent reductive current can be monitored which is inhibited by cyanide in a concentration-dependent manner. Oxygen depletion in the reaction layer can be minimized by addressing enzyme activity using a potential pulsing routine. Enzyme activity is electrochemically initiated and terminated and the sensor becomes capable of continuous monitoring. Cyanide poisoning of the biological component is reversible, and it can be reused after rinsing. The resulting sensor detects cyanide based on its biological activity rather than its physical or chemical properties.

Automatic calibration and control system for a combined oxygen and combustibles analyzer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woolbert, G.D.; Jewett, S.Y.; Robertson, J.W. Jr.

1989-08-01

This patent describes an automatic, periodically calibrating system for continuous output of calibrated signals from a combined oxygen and combustibles analyzer. It comprises: a combined oxygen and combustibles analyzer for sensing a level of oxygen and a level of combustibles in a volatile atmosphere and for producing a first sample signal indicative of the oxygen level and a second sample signal indicative of the combustibles level; means for introducing zero and span calibration test gases into the analyzer; means for periodically calibrating the analyzer. This including: a data control unit; a timer unit; a mechanical unit, means for calculating zeromore » and span values for oxygen and combustibles, means for comparing the calculated zero and span values for oxygen and combustibles to the preset alarm limits for oxygen and combustibles, means for activating an operator alarm, means for calculating oxygen and combustibles drift adjustments, a memory unit; and means for applying the oxygen and combustibles drift adjustments concurrently to the first and second sample signals, according to predetermined mathematical relationship, to obtain calibrated output signals indicative of the oxygen and combustibles level in the volatile atmosphere.« less

Redox sensing molecular mechanism of an iron metabolism regulatory protein FBXL5.

PubMed

Wei, Yaozhu; Yuan, Hong; Xu, Pengbiao; Tan, Xiangshi

2017-02-15

FBXL5 is a subunit of the SCF FBXL5 ubiquitin ligase complex that targets the proteasomal degradation of iron regulatory protein IRP2, which is an important regulator in iron metabolism. The degradation of FBXL5 itself is regulated in an iron- and oxygen-responsive manner through its diiron center containing Hr-like domain. Although the crystal structure of the Hr-like domain of FBXL5 and its degradation based on iron/oxygen sensing has been reported, the redox sensing molecular mechanism is still not clear. Herein the redox properties of FBXL5 were investigated via EPR, direct electrochemistry, SRCD, fluorescence emission spectroscopy, and redox kinetics. The results indicated that the conformation and function of FBXL5 are tuned by the redox states of the diiron center. The redox reactions of the diiron center are accompanied with conformational changes and iron release, which are associated with FBXL5 stability and degradation. These results provide insights into the redox sensing mechanism by which FBXL5 can serve as an iron metabolism regulator within mammalian cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Spatially resolved frequency domain phosphorescence lifetime-based oxygen sensing for photodynamic therapy

NASA Astrophysics Data System (ADS)

Lai, Benjamin; Gurari, Mark; Wee, Wallace; Lilge, Lothar

2008-06-01

Photodynamic Therapy (PDT) is a minimally invasive treatment that uses a photosensitive drug into convert triplet state oxygen (3O2) to singlet oxygen (1O2) to destroy malignant tissue. A fiber-optic system based on frequency domain detection of phosphorescence quenching by 3O2 is described which optically measures the distribution of 3O2 in the treatment volume during PDT to permit adjustments of treatment parameters to improve outcome. A specially designed fiber optic probe containing phosphorescent sensors embedded along its length permit spatially resolved measurements. Each sensor is composed of a phosphorescent metalloporphyrin compound that emits a characteristic spectrum. Four candidate sensors with high absorption at the excitation wavelength of 405nm and emission in the 650nm to 700nm region are considered. The dependence of phosphorescence lifetime (τ) on 3O2 concentration is described by the linearized Stern-Volmer relationship as being inversely proportional. Determination of τ, and hence 3O2 concentration, is accomplished in the frequency domain by means of phase-modulation detection of the phosphorescence signal due to an amplitude modulated excitation. The τ's of each sensor are recovered by performing global non-linear least squares fit on the measured phase and modulation index over a range of frequencies and wavelengths. With the τ of each sensor known, the oxygen concentration at each sensor's location can be determined with the Stern-Volmer relationship.

A Comprehensive Review on Water Quality Parameters Estimation Using Remote Sensing Techniques.

PubMed

Gholizadeh, Mohammad Haji; Melesse, Assefa M; Reddi, Lakshmi

2016-08-16

Remotely sensed data can reinforce the abilities of water resources researchers and decision makers to monitor waterbodies more effectively. Remote sensing techniques have been widely used to measure the qualitative parameters of waterbodies (i.e., suspended sediments, colored dissolved organic matter (CDOM), chlorophyll-a, and pollutants). A large number of different sensors on board various satellites and other platforms, such as airplanes, are currently used to measure the amount of radiation at different wavelengths reflected from the water's surface. In this review paper, various properties (spectral, spatial and temporal, etc.) of the more commonly employed spaceborne and airborne sensors are tabulated to be used as a sensor selection guide. Furthermore, this paper investigates the commonly used approaches and sensors employed in evaluating and quantifying the eleven water quality parameters. The parameters include: chlorophyll-a (chl-a), colored dissolved organic matters (CDOM), Secchi disk depth (SDD), turbidity, total suspended sediments (TSS), water temperature (WT), total phosphorus (TP), sea surface salinity (SSS), dissolved oxygen (DO), biochemical oxygen demand (BOD) and chemical oxygen demand (COD).

A Comprehensive Review on Water Quality Parameters Estimation Using Remote Sensing Techniques

PubMed Central

Gholizadeh, Mohammad Haji; Melesse, Assefa M.; Reddi, Lakshmi

2016-01-01

Remotely sensed data can reinforce the abilities of water resources researchers and decision makers to monitor waterbodies more effectively. Remote sensing techniques have been widely used to measure the qualitative parameters of waterbodies (i.e., suspended sediments, colored dissolved organic matter (CDOM), chlorophyll-a, and pollutants). A large number of different sensors on board various satellites and other platforms, such as airplanes, are currently used to measure the amount of radiation at different wavelengths reflected from the water’s surface. In this review paper, various properties (spectral, spatial and temporal, etc.) of the more commonly employed spaceborne and airborne sensors are tabulated to be used as a sensor selection guide. Furthermore, this paper investigates the commonly used approaches and sensors employed in evaluating and quantifying the eleven water quality parameters. The parameters include: chlorophyll-a (chl-a), colored dissolved organic matters (CDOM), Secchi disk depth (SDD), turbidity, total suspended sediments (TSS), water temperature (WT), total phosphorus (TP), sea surface salinity (SSS), dissolved oxygen (DO), biochemical oxygen demand (BOD) and chemical oxygen demand (COD). PMID:27537896

Blood oxygenation and flow measurements using a single 720-nm tunable V-cavity laser.

PubMed

Feng, Yafei; Deng, Haoyu; Chen, Xin; He, Jian-Jun

2017-08-01

We propose and demonstrate a single-laser-based sensing method for measuring both blood oxygenation and microvascular blood flow. Based on the optimal wavelength range found from theoretical analysis on differential absorption based blood oxygenation measurement, we designed and fabricated a 720-nm-band wavelength tunable V-cavity laser. Without any grating or bandgap engineering, the laser has a wavelength tuning range of 14.1 nm. By using the laser emitting at 710.3 nm and 724.4 nm to measure the oxygenation and blood flow, we experimentally demonstrate the proposed method.

Sense of Belonging and Hope in the Lives of Persons with Schizophrenia

PubMed Central

Barut, Jennifer K.; Dietrich, Mary S.; Zanoni, Paul A.; Ridner, Sheila H.

2015-01-01

This qualitative study used semi-structured interviews to explore the meaning of sense of belonging and hope in the lived experiences of 20 persons with chronic schizophrenia-spectrum disorders receiving acute inpatient treatment. Experience of treatment was also explored. Sense of belonging and hope were both identified as valuable or even vital, yet the experiences of not belonging and/or feeling hopeless was more prevalent. Participants frequently felt like an outsider and experienced loneliness and isolation, suggesting a need for further exploration of the impact of sense of belonging and hope on recovery and even treatment adherence in persons with schizophrenia. PMID:26992868

The levels and kinetics of oxygen tension detectable at the surface of human dermal fibroblast cultures.

PubMed

Tokuda, Y; Crane, S; Yamaguchi, Y; Zhou, L; Falanga, V

2000-03-01

Low oxygen tension has recently been shown to stimulate cell growth and clonal expansion, as well as synthesis and transcription of certain growth factors and extracellular matrix components. These results have been obtained by exposing cell cultures to a hypoxic environment. Using an oxygen probe, we have now studied how experimental conditions affect the oxygen tension detectable at the cell surface. Dissolved oxygen tension was directly related to the height of the medium above the cell surface (r = 0.8793, P = 0.021), but was constant when no cells were present in the flask (r = -0. 9732, P = 0.001). In both human dermal fibroblasts and NIH/3T3 cultures, oxygen tension decreased linearly as cell density increased (r = -0.835, P < 0.0001; r = -0.916, P < 0.0001, respectively). When human dermal fibroblasts were exposed to 2% O(2), maximum hypoxic levels (0 mmHg) were achieved within approximately 15 min, and the recovery time was within a similar time frame. The addition of rotenone, an inhibitor of cellular respiration, blocked this decrease in oxygen tension at the cell surface, suggesting that cellular consumption of oxygen is responsible for the decline. Finally, we examined the cell-surface oxygen tension in control and acutely wounded human skin equivalents (HSE), consisting of a keratinocyte layer over a type I collagen matrix containing fibroblasts. We found that oxygen tension dropped significantly (P < 0.0001) in acutely wounded areas of HSE as compared to unwounded areas of HSE and that this drop was prevented by the addition of mitomycin C. These results indicate that cell-surface oxygen tension is indirectly related to cell density, and that the amount of detectable oxygen at the cell surface is a function of cell density, the oxygen tension in the incubator, and increased cellular activity, as occurs after injury. Copyright 2000 Wiley-Liss, Inc.

Exposure to 100% Oxygen Abolishes the Impairment of Fracture Healing after Thoracic Trauma

PubMed Central

Kemmler, Julia; Bindl, Ronny; McCook, Oscar; Wagner, Florian; Gröger, Michael; Wagner, Katja; Scheuerle, Angelika; Radermacher, Peter; Ignatius, Anita

2015-01-01

In polytrauma patients a thoracic trauma is one of the most critical injuries and an important trigger of post-traumatic inflammation. About 50% of patients with thoracic trauma are additionally affected by bone fractures. The risk for fracture malunion is considerably increased in such patients, the pathomechanisms being poorly understood. Thoracic trauma causes regional alveolar hypoxia and, subsequently, hypoxemia, which in turn triggers local and systemic inflammation. Therefore, we aimed to unravel the role of oxygen in impaired bone regeneration after thoracic trauma. We hypothesized that short-term breathing of 100% oxygen in the early post-traumatic phase ameliorates inflammation and improves bone regeneration. Mice underwent a femur osteotomy alone or combined with blunt chest trauma 100% oxygen was administered immediately after trauma for two separate 3 hour intervals. Arterial blood gas tensions, microcirculatory perfusion and oxygenation were assessed at 3, 9 and 24 hours after injury. Inflammatory cytokines and markers of oxidative/nitrosative stress were measured in plasma, lung and fracture hematoma. Bone healing was assessed on day 7, 14 and 21. Thoracic trauma induced pulmonary and systemic inflammation and impaired bone healing. Short-term exposure to 100% oxygen in the acute post-traumatic phase significantly attenuated systemic and local inflammatory responses and improved fracture healing without provoking toxic side effects, suggesting that hyperoxia could induce anti-inflammatory and pro-regenerative effects after severe injury. These results suggest that breathing of 100% oxygen in the acute post-traumatic phase might reduce the risk of poorly healing fractures in severely injured patients. PMID:26147725

[Importance of mechanical assist devices in acute circulatory arrest].

PubMed

Ferrari, Markus Wolfgang

2016-03-01

Mechanical assist devices are indicated for hemodynamic stabilization in acute circulatory arrest if conventional means of cardiopulmonary resuscitation are unable to re-establish adequate organ perfusion. Their temporary use facilitates further diagnostic and therapeutic options in selected patients, e.g. coronary angiography followed by revascularization.External thorax compression devices allow sufficient cardiac massage in case of preclinical or in-hospital circulatory arrest, especially under complex transfer conditions. These devices perform standardized thorax compressions at a rate of 80-100 per minute. Invasive mechanical support devices are used in the catheter laboratory or in the intensive care unit. Axial turbine pumps, e.g. the Impella, continuously pump blood from the left ventricle into the aortic root. The Impella can also provide right ventricle support by pumping blood from the vena cava into the pulmonary artery. So-called emergency systems or ECMO devices consist of a centrifugal pump and a membrane oxygenator allowing complete takeover of cardiac and pulmonary functions. Withdrawing blood from the right atrium and vena cava, oxygenated blood is returned to the abdominal aorta. Isolated centrifugal pumps provide left heart support without an oxygenator after transseptal insertion of a venous cannula into the left atrium.Mechanical assist devices are indicated for acute organ protection and hemodynamic stabilization for diagnostic and therapeutic measures as well as bridge to myocardial recovery. Future technical developments and better insights into the pathophysiology of mechanical circulatory support will broaden the spectrum of indications of such devices in acute circulatory arrest.

Pulsed Dose Delivery of Oxygen in Mechanically Ventilated Pigs with Acute Lung Injury

DTIC Science & Technology

2013-03-01

collapse or arrhythmia were encountered after administration of oleic acid, chest compressions, electrical defibrillation , and epinephrine (0.1-1 mg/kg...endotracheal tube to continuously measure the oxygen content of the gas in the circuit. We designed the study as a crossover trial, so each animal served as... designed to prove that a pulsed dose delivery system would be a better method of oxygen delivery, it is interesting to note that pulsed dose delivery did

Oxygen Sensing for Industrial Safety — Evolution and New Approaches

PubMed Central

Willett, Martin

2014-01-01

The requirement for the detection of oxygen in industrial safety applications has historically been met by electrochemical technologies based on the consumption of metal anodes. Products using this approach have been technically and commercially successful for more than three decades. However, a combination of new requirements is driving the development of alternative approaches offering fresh opportunities and challenges. This paper reviews some key aspects in the evolution of consumable anode products and highlights recent developments in alternative technologies aimed at meeting current and anticipated future needs in this important application. PMID:24681673

Use of the VS-sense swab in diagnosing vulvovaginitis.

PubMed

Sobel, Jack D; Nyirjesy, Paul; Kessary, Hadar; Ferris, Daron G

2009-09-01

Although pH assessment of vaginal secretions is beneficial for diagnosing vaginitis, it is not commonly done. The purpose of this study was to determine the performance characteristics of the VS-Sense (pH test) swab (Common Sense, Ltd., Caesarea, Israel) in augmenting the diagnosis of vaginitis. We prospectively studied 193 women with acute vulvovaginal symptoms and 74 asymptomatic controls at three medical centers. The VS-Sense swab was administered intravaginally, and results were interpreted by a nurse. These results were compared with final clinical and laboratory diagnoses. In women with an elevated pH caused by bacterial vaginosis (BV), trichomonas, and other types of vaginitis, the VS-Sense test sensitivity and specificity were 82.3% (102 of 124) (95% CI 74.4%-88.5%) and 94.2% (129 of 137) (95% CI 88.8%-97.4%), respectively. There was an 86.2% (95% CI 81.3%-90.1%) overall agreement between pH paper and VS-Sense swab results. The VS-Sense test offers an alternative approach to measuring vaginal pH with nitrazine paper. Use of this simple, more rapid test may facilitate the diagnosis of vulvovaginitis.

Pathophysiology of pulmonary hypertension in acute lung injury

PubMed Central

Price, Laura C.; McAuley, Danny F.; Marino, Philip S.; Finney, Simon J.; Griffiths, Mark J.

2012-01-01

Acute lung injury (ALI) and acute respiratory distress syndrome are characterized by protein rich alveolar edema, reduced lung compliance, and acute severe hypoxemia. A degree of pulmonary hypertension (PH) is also characteristic, higher levels of which are associated with increased morbidity and mortality. The increase in right ventricular (RV) afterload causes RV dysfunction and failure in some patients, with associated adverse effects on oxygen delivery. Although the introduction of lung protective ventilation strategies has probably reduced the severity of PH in ALI, a recent invasive hemodynamic analysis suggests that even in the modern era, its presence remains clinically important. We therefore sought to summarize current knowledge of the pathophysiology of PH in ALI. PMID:22246001

A Predictive Model of the Oxygen and Heme Regulatory Network in Yeast

PubMed Central

Kundaje, Anshul; Xin, Xiantong; Lan, Changgui; Lianoglou, Steve; Zhou, Mei; Zhang, Li; Leslie, Christina

2008-01-01

Deciphering gene regulatory mechanisms through the analysis of high-throughput expression data is a challenging computational problem. Previous computational studies have used large expression datasets in order to resolve fine patterns of coexpression, producing clusters or modules of potentially coregulated genes. These methods typically examine promoter sequence information, such as DNA motifs or transcription factor occupancy data, in a separate step after clustering. We needed an alternative and more integrative approach to study the oxygen regulatory network in Saccharomyces cerevisiae using a small dataset of perturbation experiments. Mechanisms of oxygen sensing and regulation underlie many physiological and pathological processes, and only a handful of oxygen regulators have been identified in previous studies. We used a new machine learning algorithm called MEDUSA to uncover detailed information about the oxygen regulatory network using genome-wide expression changes in response to perturbations in the levels of oxygen, heme, Hap1, and Co2+. MEDUSA integrates mRNA expression, promoter sequence, and ChIP-chip occupancy data to learn a model that accurately predicts the differential expression of target genes in held-out data. We used a novel margin-based score to extract significant condition-specific regulators and assemble a global map of the oxygen sensing and regulatory network. This network includes both known oxygen and heme regulators, such as Hap1, Mga2, Hap4, and Upc2, as well as many new candidate regulators. MEDUSA also identified many DNA motifs that are consistent with previous experimentally identified transcription factor binding sites. Because MEDUSA's regulatory program associates regulators to target genes through their promoter sequences, we directly tested the predicted regulators for OLE1, a gene specifically induced under hypoxia, by experimental analysis of the activity of its promoter. In each case, deletion of the candidate

Unintended inhalation of nitric oxide by contamination of compressed air: physiologic effects and interference with intended nitric oxide inhalation in acute lung injury.

PubMed

Benzing, A; Loop, T; Mols, G; Geiger, K

1999-10-01

Compressed air from a hospital's central gas supply may contain nitric oxide as a result of air pollution. Inhaled nitric oxide may increase arterial oxygen tension and decrease pulmonary vascular resistance in patients with acute lung injury and acute respiratory distress syndrome. Therefore, the authors wanted to determine whether unintentional nitric oxide inhalation by contamination of compressed air influences arterial oxygen tension and pulmonary vascular resistance and interferes with the therapeutic use of nitric oxide. Nitric oxide concentrations in the compressed air of a university hospital were measured continuously by chemiluminescence during two periods (4 and 2 weeks). The effects of unintended nitric oxide inhalation on arterial oxygen tension (n = 15) and on pulmonary vascular resistance (n = 9) were measured in patients with acute lung injury and acute respiratory distress syndrome by changing the source of compressed air of the ventilator from the hospital's central gas supply to a nitric oxide-free gas tank containing compressed air. In five of these patients, the effects of an additional inhalation of 5 ppm nitric oxide were evaluated. During working days, compressed air of the hospital's central gas supply contained clinically effective nitric oxide concentrations (> 80 parts per billion) during 40% of the time. Change to gas tank-supplied nitric oxide-free compressed air decreased the arterial oxygen tension by 10% and increased pulmonary vascular resistance by 13%. The addition of 5 ppm nitric oxide had a minimal effect on arterial oxygen tension and pulmonary vascular resistance when added to hospital-supplied compressed air but improved both when added to tank-supplied compressed air. Unintended inhalation of nitric oxide increases arterial oxygen tension and decreases pulmonary vascular resistance in patients with acute lung injury and acute respiratory distress syndrome. The unintended nitric oxide inhalation interferes with the

Topical oxygen emulsion: a novel wound therapy.

PubMed

Davis, Stephen C; Cazzaniga, Alejandro L; Ricotti, Carlos; Zalesky, Paul; Hsu, Li-Chien; Creech, Jeffrey; Eaglstein, William H; Mertz, Patricia M

2007-10-01

To investigate the use of a topical oxygen emulsion (TOE), consisting of a supersaturated oxygen suspension using perfluorocarbon components, on second-degree burns and partial-thickness wounds. Oxygen is a required substance for various aspects of wound repair, and increased oxygen tension in a wound has been shown to stimulate phagocytosis and to reduce the incidence of wound infection. Second-degree burns and partial-thickness wounds were created on the backs of specific pathogen-free pigs. Wounds were then randomly assigned to 1 of the following treatment groups: TOE, TOE vehicle, or air-exposed control. Wounds were assessed for complete epithelialization using a salt-split technique. The TOE was able to significantly (P = .001) enhance the rate of epithelialization compared with both vehicle and untreated control. These data suggest that topical oxygen may be beneficial for acute and burn wounds. The results obtained from this double-blind, control, in vivo study demonstrate that TOE can significantly enhance the rate of epithelialization of partial-thickness excisional wounds and second-degree burns. These findings could have considerable clinical implications for patients with surgical and burn wounds by providing functional skin at an earlier date to act as a barrier against environmental factors, such as bacteria invasion. Other types of wounds may also benefit from this therapy (eg, chronic wounds and surgical incisions). Additional studies, including clinical studies, are warranted.

Hyperbaric oxygen therapy for carbon monoxide poisoning.

PubMed

Weaver, Lindell K

2014-01-01

Despite established exposure limits and safety standards, and the availability of carbon monoxide (CO) alarms, each year 50,000 people in the United States visit emergency departments for CO poisoning. Carbon monoxide poisoning can occur from brief exposures to high levels of CO, or from longer exposures to lower levels. Common symptoms include headaches, nausea and vomiting, dizziness, general malaise, and altered mental status. Some patients may have chest pain, shortness of breath and myocardial ischemia, and may require mechanical ventilation and treatment of shock. Individuals poisoned by CO often go on to develop neurological problems, including cognitive sequelae, anxiety and depression, persistent headaches, dizziness, sleep problems, motor weakness, vestibular and balance problems, gaze abnormalities, peripheral neuropathies, hearing loss, tinnitus and Parkinsonian-like syndrome. While breathing oxygen hastens the removal of carboxyhemoglobin (COHb), hyperbaric oxygen (HBO2) hastens COHb elimination and favorably modulates inflammatory processes instigated by CO poisoning, an effect not observed with breathing normobaric oxygen. Hyperbaric oxygen improves mitochondrial function, inhibits lipid peroxidation transiently, impairs leukocyte adhesion to injured microvasculature, and reduces brain inflammation caused by the CO-induced adduct formation of myelin basic protein. Based upon three supportive randomized clinical trials in humans and considerable evidence from animal studies, HBO2 should be considered for all cases of acute symptomatic CO poisoning. Hyperbaric oxygen is indicated for CO poisoning complicated by cyanide poisoning, often concomitantly with smoke inhalation.

Enzymatic glucose sensor compensation for variations in ambient oxygen concentration

NASA Astrophysics Data System (ADS)

Collier, Bradley B.; McShane, Michael J.

2013-02-01

Due to the increasing prevalence of diabetes, research toward painless glucose sensing continues. Oxygen sensitive phosphors with glucose oxidase (GOx) can be used to determine glucose levels indirectly by monitoring oxygen consumption. This is an attractive combination because of its speed and specificity. Packaging these molecules together in "smart materials" for implantation will enable non-invasive glucose monitoring. As glucose levels increase, oxygen levels decrease; consequently, the luminescence intensity and lifetime of the phosphor increase. Although the response of the sensor is dependent on glucose concentration, the ambient oxygen concentration also plays a key role. This could lead to inaccurate glucose readings and increase the risk of hyper- or hypoglycemia. To mitigate this risk, the dependence of hydrogel glucose sensor response on oxygen levels was investigated and compensation methods explored. Sensors were calibrated at different oxygen concentrations using a single generic logistic equation, such that trends in oxygen-dependence were determined as varying parameters in the equation. Each parameter was found to be a function of oxygen concentration, such that the correct glucose calibration equation can be calculated if the oxygen level is known. Accuracy of compensation will be determined by developing an overall calibration, using both glucose and oxygen sensors in parallel, correcting for oxygen fluctuations in real time by intentionally varying oxygen, and calculating the error in actual and predicted glucose levels. While this method was developed for compensation of enzymatic glucose sensors, in principle it can also be implemented with other kinds of sensors utilizing oxidases.

Hydrogen sulfide as an oxygen sensor.

PubMed

Olson, Kenneth R

2015-02-10

Although oxygen (O2)-sensing cells and tissues have been known for decades, the identity of the O2-sensing mechanism has remained elusive. Evidence is accumulating that O2-dependent metabolism of hydrogen sulfide (H2S) is this enigmatic O2 sensor. The elucidation of biochemical pathways involved in H2S synthesis and metabolism have shown that reciprocal H2S/O2 interactions have been inexorably linked throughout eukaryotic evolution; there are multiple foci by which O2 controls H2S inactivation, and the effects of H2S on downstream signaling events are consistent with those activated by hypoxia. H2S-mediated O2 sensing has been demonstrated in a variety of O2-sensing tissues in vertebrate cardiovascular and respiratory systems, including smooth muscle in systemic and respiratory blood vessels and airways, carotid body, adrenal medulla, and other peripheral as well as central chemoreceptors. Information is now needed on the intracellular location and stoichometry of these signaling processes and how and which downstream effectors are activated by H2S and its metabolites. Development of specific inhibitors of H2S metabolism and effector activation as well as cellular organelle-targeted compounds that release H2S in a time- or environmentally controlled way will not only enhance our understanding of this signaling process but also provide direction for future therapeutic applications.

No oxygen? No problem! Intrinsic brain tolerance to hypoxia in vertebrates

PubMed Central

Larson, John; Drew, Kelly L.; Folkow, Lars P.; Milton, Sarah L.; Park, Thomas J.

2014-01-01

Many vertebrates are challenged by either chronic or acute episodes of low oxygen availability in their natural environments. Brain function is especially vulnerable to the effects of hypoxia and can be irreversibly impaired by even brief periods of low oxygen supply. This review describes recent research on physiological mechanisms that have evolved in certain vertebrate species to cope with brain hypoxia. Four model systems are considered: freshwater turtles that can survive for months trapped in frozen-over lakes, arctic ground squirrels that respire at extremely low rates during winter hibernation, seals and whales that undertake breath-hold dives lasting minutes to hours, and naked mole-rats that live in crowded burrows completely underground for their entire lives. These species exhibit remarkable specializations of brain physiology that adapt them for acute or chronic episodes of hypoxia. These specializations may be reactive in nature, involving modifications to the catastrophic sequelae of oxygen deprivation that occur in non-tolerant species, or preparatory in nature, preventing the activation of those sequelae altogether. Better understanding of the mechanisms used by these hypoxia-tolerant vertebrates will increase appreciation of how nervous systems are adapted for life in specific ecological niches as well as inform advances in therapy for neurological conditions such as stroke and epilepsy. PMID:24671961

A Quantitative Study of Oxygen as a Metabolic Regulator

NASA Technical Reports Server (NTRS)

Radhakrishnan, Krishnan; LaManna, Joseph C.; Cabera, Marco E.

2000-01-01

An acute reduction in oxygen delivery to a tissue is associated with metabolic changes aimed at maintaining ATP homeostasis. However, given the complexity of the human bio-energetic system, it is difficult to determine quantitatively how cellular metabolic processes interact to maintain ATP homeostasis during stress (e.g., hypoxia, ischemia, and exercise). In particular, we are interested in determining mechanisms relating cellular oxygen concentration to observed metabolic responses at the cellular, tissue, organ, and whole body levels and in quantifying how changes in tissue oxygen availability affect the pathways of ATP synthesis and the metabolites that control these pathways. In this study; we extend a previously developed mathematical model of human bioenergetics, to provide a physicochemical framework that permits quantitative understanding of oxygen as a metabolic regulator. Specifically, the enhancement - sensitivity analysis - permits studying the effects of variations in tissue oxygenation and parameters controlling cellular respiration on glycolysis, lactate production, and pyruvate oxidation. The analysis can distinguish between parameters that must be determined accurately and those that require less precision, based on their effects on model predictions. This capability may prove to be important in optimizing experimental design, thus reducing use of animals.

A prospective, observational clinical trial of fever reduction to reduce systemic oxygen consumption in the setting of acute brain injury.

PubMed

Hata, J Steven; Shelsky, Constance R; Hindman, Bradley J; Smith, Thomas C; Simmons, Jonathan S; Todd, Michael M

2008-01-01

Fever after acute brain injury appears to be a detrimental factor, associated with impaired neurological outcomes. This study assessed physiological changes in systemic oxygen consumption (VO2) during cutaneous cooling after severe brain injury. This prospective, observational, clinical study evaluated ten, critically ill, brain-injured patients requiring mechanical ventilation with a core body temperature of greater or equal to 38 degrees C. Febrile patients failing to defervesce after acetaminophen underwent indirect calorimetry for a 1-hour baseline period followed by a 4 h cooling period. The Arctic Sun(R) Temperature Management System (Medivance) directed core temperature to a goal of 36 degrees C. The patients had a mean age of 32 years (95% CI 23, 40), Glasgow Coma Scale of 6 (95% CI 5,7), and APACHE 2 score of 19 (95% CI 15, 22), with 8 of 10 patients suffering traumatic brain injuries. The baseline 1-h core temperature was significantly reduced from 38.6 degrees +/- 0.9 to 36.3 degrees +/- 1.2 degrees C (P < 0.0001) over 4 h. Two cohorts were identified based upon the presence or absence of shivering. Within the non-shivering cohort, systemic VO2 was significantly reduced from 415 +/- 123 to 308 +/- 115 ml/min (-27 +/- 18%) (P < 0.05). In contrast, those with shivering showed no significant reduction in VO2, despite significantly decreasing core temperature. The overall percentage change of VCO2 correlated with VO2 (r (2) = 0.91). Fever reduction in acute brain injury appears to significantly reduce systemic VO2, but is highly dependent on shivering control.

Plasma corticosteroid dynamics in channel catfish, Ictalurus punctatus (Rafinesque), during and after oxygen depletion

USGS Publications Warehouse

Tomasso J.R., Davis; Parker, N.C.

1981-01-01

Plasma corticosteroid concentrations in channel catfish, Ictalurus punctatus, (normally 1.0 ± 0.3 μg/100 ml) increased significantly (to 5.9 ± 1.2μg/100 ml) in response to acute oxygen depletion and then returned to control levels within 30 min after the dissolved oxygen concentration was increased; however, a secondary increase in plasma corticosteroid levels was observed 6 h after exposure. Corticosteroid levels also increased in fish exposed to dissolved oxygen concentration of <0.2 mg/1 for three days. Methylene blue was not effective in preventing interrenal response to low dissolved oxygen. No diurnal plasma corticosteroid rhythm was observed in fish exposed to diurnal chemical rhythms of culture ponds.

Adult venovenous extracorporeal membrane oxygenation for severe respiratory failure: Current status and future perspectives.

PubMed

Sen, Ayan; Callisen, Hannelisa E; Alwardt, Cory M; Larson, Joel S; Lowell, Amelia A; Libricz, Stacy L; Tarwade, Pritee; Patel, Bhavesh M; Ramakrishna, Harish

2016-01-01

Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure was proposed more than 40 years ago. Despite the publication of the ARDSNet study and adoption of lung protective ventilation, the mortality for acute respiratory failure due to acute respiratory distress syndrome has continued to remain high. This technology has evolved over the past couple of decades and has been noted to be safe and successful, especially during the worldwide H1N1 influenza pandemic with good survival rates. The primary indications for ECMO in acute respiratory failure include severe refractory hypoxemic and hypercarbic respiratory failure in spite of maximum lung protective ventilatory support. Various triage criteria have been described and published. Contraindications exist when application of ECMO may be futile or technically impossible. Knowledge and appreciation of the circuit, cannulae, and the physiology of gas exchange with ECMO are necessary to ensure lung rest, efficiency of oxygenation, and ventilation as well as troubleshooting problems. Anticoagulation is a major concern with ECMO, and the evidence is evolving with respect to diagnostic testing and use of anticoagulants. Clinical management of the patient includes comprehensive critical care addressing sedation and neurologic issues, ensuring lung recruitment, diuresis, early enteral nutrition, treatment and surveillance of infections, and multisystem organ support. Newer technology that delinks oxygenation and ventilation by extracorporeal carbon dioxide removal may lead to ultra-lung protective ventilation, avoidance of endotracheal intubation in some situations, and ambulatory therapies as a bridge to lung transplantation. Risks, complications, and long-term outcomes and resources need to be considered and weighed in before widespread application. Ethical challenges are a reality and a multidisciplinary approach that should be adopted for every case in consideration.

Hydrogen Sulfide as an Oxygen Sensor

PubMed Central

2015-01-01

Abstract Significance Although oxygen (O2)-sensing cells and tissues have been known for decades, the identity of the O2-sensing mechanism has remained elusive. Evidence is accumulating that O2-dependent metabolism of hydrogen sulfide (H2S) is this enigmatic O2 sensor. Recent Advances The elucidation of biochemical pathways involved in H2S synthesis and metabolism have shown that reciprocal H2S/O2 interactions have been inexorably linked throughout eukaryotic evolution; there are multiple foci by which O2 controls H2S inactivation, and the effects of H2S on downstream signaling events are consistent with those activated by hypoxia. H2S-mediated O2 sensing has been demonstrated in a variety of O2-sensing tissues in vertebrate cardiovascular and respiratory systems, including smooth muscle in systemic and respiratory blood vessels and airways, carotid body, adrenal medulla, and other peripheral as well as central chemoreceptors. Critical Issues Information is now needed on the intracellular location and stoichometry of these signaling processes and how and which downstream effectors are activated by H2S and its metabolites. Future Directions Development of specific inhibitors of H2S metabolism and effector activation as well as cellular organelle-targeted compounds that release H2S in a time- or environmentally controlled way will not only enhance our understanding of this signaling process but also provide direction for future therapeutic applications. Antioxid. Redox Signal. 22, 377–397. “Nothing in Biology Makes Sense Except in the Light of Evolution” —Theodosius Dobzhansky (29) PMID:24801248

Pulmonary gas exchange in acute respiratory failure.

PubMed

Rodriguez-Roisin, R

1994-01-01

The principal function of the lung is to facilitate the exchange of the respiratory gases, oxygen (O2) and carbon dioxide (CO2). When the lung fails as a gas exchanger respiratory failure ensues. Clinically, it is generally accepted that an arterial oxygen tension (PaO2) of less than 60 mmHg or a PaCO2 of greater than 50 mmHg, or both, whilst breathing room air are values consistent with the concept of respiratory failure. This article will deal, firstly, with some basic aspects of the physiology of pulmonary gas exchange and more specifically on the measurement of ventilation-perfusion (VA/Q) relationships, the most influential factor determining hypoxaemia. The second part highlights the most important findings on pulmonary gas exchange in the adult respiratory distress syndrome (ARDS) and other common acute respiratory failure conditions, such as pneumonia, acute exacerbation of chronic obstructive pulmonary disease (COPD) and status asthmaticus, based on the data obtained by means of the multiple inert gas elimination approach, a technique which gives a detailed picture of VA/Q ratio distributions.

Position paper for the organization of extracorporeal membrane oxygenation programs for acute respiratory failure in adult patients.

PubMed

Combes, Alain; Brodie, Daniel; Bartlett, Robert; Brochard, Laurent; Brower, Roy; Conrad, Steve; De Backer, Daniel; Fan, Eddy; Ferguson, Niall; Fortenberry, James; Fraser, John; Gattinoni, Luciano; Lynch, William; MacLaren, Graeme; Mercat, Alain; Mueller, Thomas; Ogino, Mark; Peek, Giles; Pellegrino, Vince; Pesenti, Antonio; Ranieri, Marco; Slutsky, Arthur; Vuylsteke, Alain

2014-09-01

The use of extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure (ARF) in adults is growing rapidly given recent advances in technology, even though there is controversy regarding the evidence justifying its use. Because ECMO is a complex, high-risk, and costly modality, at present it should be conducted in centers with sufficient experience, volume, and expertise to ensure it is used safely. This position paper represents the consensus opinion of an international group of physicians and associated health-care workers who have expertise in therapeutic modalities used in the treatment of patients with severe ARF, with a focus on ECMO. The aim of this paper is to provide physicians, ECMO center directors and coordinators, hospital directors, health-care organizations, and regional, national, and international policy makers a description of the optimal approach to organizing ECMO programs for ARF in adult patients. Importantly, this will help ensure that ECMO is delivered safely and proficiently, such that future observational and randomized clinical trials assessing this technique may be performed by experienced centers under homogeneous and optimal conditions. Given the need for further evidence, we encourage restraint in the widespread use of ECMO until we have a better appreciation for both the potential clinical applications and the optimal techniques for performing ECMO.

The use of oxygen in cluster headache treatment worldwide - a survey of the International Headache Society (IHS).

PubMed

Evers, Stefan; Rapoport, Alan

2017-04-01

Background Oxygen is recommended for the treatment of acute cluster headache attacks. However, it is not available worldwide. Methods The International Headache Society performed a survey among its national member societies on the availability and the restrictions for oxygen in the treatment of cluster headache. Results Oxygen is reimbursed in 50% of all countries responding ( n = 22). There are additional restrictions in the reimbursement of the facial mask and with respect to age. Conclusion Oxygen for the treatment of cluster headache attack is not reimbursed worldwide. Headache societies should pressure national/public health authorities to reimburse oxygen for cluster headache in all countries.

Regulation of singlet oxygen-induced apoptosis by cytosolic NADP+-dependent isocitrate dehydrogenase.

PubMed

Kim, Sun Yee; Lee, Su Min; Tak, Jean Kyoung; Choi, Kyeong Sook; Kwon, Taeg Kyu; Park, Jeen-Woo

2007-08-01

Singlet oxygen is a highly reactive form of molecular oxygen that may harm living systems by oxidizing critical cellular macromolecules and it also promotes deleterious processes such as cell death. Recently, we demonstrated that the control of redox balance and the cellular defense against oxidative damage are the primary functions of cytosolic NADP(+)-dependent isocitrate dehydrogenase (IDPc) through supplying NADPH for antioxidant systems. In this report, we demonstrate that modulation of IDPc activity in HL-60 cells regulates singlet oxygen-induced apoptosis. When we examined the protective role of IDPc against singlet oxygen-induced apoptosis with HL-60 cells transfected with the cDNA for mouse IDPc in sense and antisense orientations, a clear inverse relationship was observed between the amount of IDPc expressed in target cells and their susceptibility to apoptosis. The results suggest that IDPc plays an important protective role in apoptosis of HL-60 cells induced by singlet oxygen.

Optical methods and systems for detecting a constituent in a gas containing oxygen in harsh environments

DOEpatents

Carpenter, Michael A [Scotia, NY; Sirinakis, George [Bronx, NY

2011-01-04

A method for detecting a gas phase constituent such as carbon monoxide, nitrogen dioxide, hydrogen, or hydrocarbons in a gas comprising oxygen such as air, includes providing a sensing material or film having a metal embedded in a catalytically active matrix such as gold embedded in a yttria stabilized zirconia (YSZ) matrix. The method may include annealing the sensing material at about 900.degree. C., exposing the sensing material and gas to a temperature above 400.degree. C., projecting light onto the sensing material, and detecting a change in the absorption spectrum of the sensing material due to the exposure of the sensing material to the gas in air at the temperature which causes a chemical reaction in the sensing material compared to the absorption spectrum of the sensing material in the absence of the gas. Systems employing such a method are also disclosed.

The Ratio of Partial Pressure Arterial Oxygen and Fraction of Inspired Oxygen 1 Day After Acute Respiratory Distress Syndrome Onset Can Predict the Outcomes of Involving Patients.

PubMed

Lai, Chih-Cheng; Sung, Mei-I; Liu, Hsiao-Hua; Chen, Chin-Ming; Chiang, Shyh-Ren; Liu, Wei-Lun; Chao, Chien-Ming; Ho, Chung-Han; Weng, Shih-Feng; Hsing, Shu-Chen; Cheng, Kuo-Chen

2016-04-01

The initial hypoxemic level of acute respiratory distress syndrome (ARDS) defined according to Berlin definition might not be the optimal predictor for prognosis. We aimed to determine the predictive validity of the stabilized ratio of partial pressure arterial oxygen and fraction of inspired oxygen (PaO2/FiO2 ratio) following standard ventilator setting in the prognosis of patients with ARDS.This prospective observational study was conducted in a single tertiary medical center in Taiwan and compared the stabilized PaO2/FiO2 ratio (Day 1) following standard ventilator settings and the PaO2/FiO2 ratio on the day patients met ARDS Berlin criteria (Day 0). Patients admitted to intensive care units and in accordance with the Berlin criteria for ARDS were collected between December 1, 2012 and May 31, 2015. Main outcome was 28-day mortality. Arterial blood gas and ventilator setting on Days 0 and 1 were obtained.A total of 238 patients met the Berlin criteria for ARDS were enrolled, and they were classified as mild (n = 50), moderate (n = 125), and severe (n = 63) ARDS, respectively. Twelve (5%) patients who originally were classified as ARDS did not continually meet the Berlin definition, and a total of 134 (56%) patients had the changes regarding the severity of ARDS from Day 0 to Day 1. The 28-day mortality rate was 49.1%, and multivariate analysis identified age, PaO2/FiO2 on Day 1, number of organ failures, and positive fluid balance within 5 days as significant risk factors of death. Moreover, the area under receiver-operating curve for mortality prediction using PaO2/FiO2 on Day 1 was significant higher than that on Day 0 (P = 0.016).PaO2/FiO2 ratio on Day 1 after applying mechanical ventilator is a better predictor of outcomes in patients with ARDS than those on Day 0.

The Ratio of Partial Pressure Arterial Oxygen and Fraction of Inspired Oxygen 1 Day After Acute Respiratory Distress Syndrome Onset Can Predict the Outcomes of Involving Patients

PubMed Central

Lai, Chih-Cheng; Sung, Mei-I; Liu, Hsiao-Hua; Chen, Chin-Ming; Chiang, Shyh-Ren; Liu, Wei-Lun; Chao, Chien-Ming; Ho, Chung-Han; Weng, Shih-Feng; Hsing, Shu-Chen; Cheng, Kuo-Chen

2016-01-01

Abstract The initial hypoxemic level of acute respiratory distress syndrome (ARDS) defined according to Berlin definition might not be the optimal predictor for prognosis. We aimed to determine the predictive validity of the stabilized ratio of partial pressure arterial oxygen and fraction of inspired oxygen (PaO2/FiO2 ratio) following standard ventilator setting in the prognosis of patients with ARDS. This prospective observational study was conducted in a single tertiary medical center in Taiwan and compared the stabilized PaO2/FiO2 ratio (Day 1) following standard ventilator settings and the PaO2/FiO2 ratio on the day patients met ARDS Berlin criteria (Day 0). Patients admitted to intensive care units and in accordance with the Berlin criteria for ARDS were collected between December 1, 2012 and May 31, 2015. Main outcome was 28-day mortality. Arterial blood gas and ventilator setting on Days 0 and 1 were obtained. A total of 238 patients met the Berlin criteria for ARDS were enrolled, and they were classified as mild (n = 50), moderate (n = 125), and severe (n = 63) ARDS, respectively. Twelve (5%) patients who originally were classified as ARDS did not continually meet the Berlin definition, and a total of 134 (56%) patients had the changes regarding the severity of ARDS from Day 0 to Day 1. The 28-day mortality rate was 49.1%, and multivariate analysis identified age, PaO2/FiO2 on Day 1, number of organ failures, and positive fluid balance within 5 days as significant risk factors of death. Moreover, the area under receiver-operating curve for mortality prediction using PaO2/FiO2 on Day 1 was significant higher than that on Day 0 (P = 0.016). PaO2/FiO2 ratio on Day 1 after applying mechanical ventilator is a better predictor of outcomes in patients with ARDS than those on Day 0. PMID:27057912

Effects of pulmonary static inflation with 50% xenon on oxygen impairment during cardiopulmonary bypass for stanford type A acute aortic dissection: A pilot study.

PubMed

Jin, Mu; Yang, Yanwei; Pan, Xudong; Lu, Jiakai; Zhang, Zhiquan; Cheng, Weiping

2017-03-01

The goal of this study was to investigate the effects of pulmonary static inflation with 50% xenon on postoperative oxygen impairment during cardiopulmonary bypass (CPB) for Stanford type A acute aortic dissection (AAD). This prospective single-center nonrandomized controlled clinical trial included 100 adult patients undergoing surgery for Stanford type A AAD at an academic hospital in China. Fifty subjects underwent pulmonary static inflation with 50% oxygen from January 2013 to January 2014, and 50 underwent inflation with 50% xenon from January 2014 to December 2014. During CPB, the lungs were inflated with either 50% xenon (xenon group) or 50% oxygen (control group) to maintain an airway pressure of 5 cm H2O. The primary outcome was oxygenation index (OI) value after intubation, and 10 minutes and 6 hours after the operation. The second outcome was cytokine and reactive oxygen species levels after intubation and 10 minutes, 6 hours, and 24 hours after the operation. Patients treated with xenon had lower OI levels compared to the control group before surgery (P = 0.002); however, there was no difference in postoperative values between the 2 groups. Following surgery, mean maximal OI values decreased by 18.8% and 33.8%, respectively, in the xenon and control groups. After surgery, the levels of interleukin-6 (IL-6), tumor necrosis factor alpha, and thromboxane B2 decreased by 23.5%, 9.1%, and 30.2%, respectively, in the xenon group, but increased by 10.8%, 26.2%, and 26.4%, respectively, in the control group. Moreover, IL-10 levels increased by 28% in the xenon group and decreased by 7.5% in the control group. There were significant time and treatment-time interaction effects on methane dicarboxylic aldehyde (P = 0.000 and P = 0.050, respectively) and myeloperoxidase (P = 0.000 and P = 0.001 in xenon and control groups, respectively). There was no difference in hospital mortality and 1-year survival rate between the 2 groups

Mitochondrial Dynamics Mediated by Mitofusin 1 Is Required for POMC Neuron Glucose-Sensing and Insulin Release Control.

PubMed

Ramírez, Sara; Gómez-Valadés, Alicia G; Schneeberger, Marc; Varela, Luis; Haddad-Tóvolli, Roberta; Altirriba, Jordi; Noguera, Eduard; Drougard, Anne; Flores-Martínez, Álvaro; Imbernón, Mónica; Chivite, Iñigo; Pozo, Macarena; Vidal-Itriago, Andrés; Garcia, Ainhoa; Cervantes, Sara; Gasa, Rosa; Nogueiras, Ruben; Gama-Pérez, Pau; Garcia-Roves, Pablo M; Cano, David A; Knauf, Claude; Servitja, Joan-Marc; Horvath, Tamas L; Gomis, Ramon; Zorzano, Antonio; Claret, Marc

2017-06-06

Proopiomelanocortin (POMC) neurons are critical sensors of nutrient availability implicated in energy balance and glucose metabolism control. However, the precise mechanisms underlying nutrient sensing in POMC neurons remain incompletely understood. We show that mitochondrial dynamics mediated by Mitofusin 1 (MFN1) in POMC neurons couple nutrient sensing with systemic glucose metabolism. Mice lacking MFN1 in POMC neurons exhibited defective mitochondrial architecture remodeling and attenuated hypothalamic gene expression programs during the fast-to-fed transition. This loss of mitochondrial flexibility in POMC neurons bidirectionally altered glucose sensing, causing abnormal glucose homeostasis due to defective insulin secretion by pancreatic β cells. Fed mice lacking MFN1 in POMC neurons displayed enhanced hypothalamic mitochondrial oxygen flux and reactive oxygen species generation. Central delivery of antioxidants was able to normalize the phenotype. Collectively, our data posit MFN1-mediated mitochondrial dynamics in POMC neurons as an intrinsic nutrient-sensing mechanism and unveil an unrecognized link between this subset of neurons and insulin release. Copyright © 2017 Elsevier Inc. All rights reserved.

LUMOS--A Sensitive and Reliable Optode System for Measuring Dissolved Oxygen in the Nanomolar Range.

PubMed

Lehner, Philipp; Larndorfer, Christoph; Garcia-Robledo, Emilio; Larsen, Morten; Borisov, Sergey M; Revsbech, Niels-Peter; Glud, Ronnie N; Canfield, Donald E; Klimant, Ingo

2015-01-01

Most commercially available optical oxygen sensors target the measuring range of 300 to 2 μmol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized "sensing chemistry" that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded in a Hyflon AD 60 polymer matrix and has a KSV of 6.25 x 10-3 ppmv-1. The applicable measurement range is from 1000 nM down to a detection limit of 0.5 nM. A second sensor material based on the platinum(II) analogue of the porphyrin is spectrally compatible with the readout device and has a measurement range of 20 μM down to 10 nM. The LUMOS device is a dedicated system optimized for a high signal to noise ratio, but in principle any phase flourimeter can be adapted to act as a readout device for the highly sensitive and robust sensing chemistry. Vise versa, the LUMOS fluorimeter can be used for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used to measure nanomolar oxygen concentrations. Oxygen contamination in common sample containers has been investigated and microbial or enzymatic oxygen consumption at nanomolar concentrations is presented.

Elimination of Gaseous Microemboli from Cardiopulmonary Bypass using Hypobaric Oxygenation

PubMed Central

Gipson, Keith E.; Rosinski, David J.; Schonberger, Robert B.; Kubera, Cathryn; Mathew, Eapen S.; Nichols, Frank; Dyckman, William; Courtin, Francois; Sherburne, Bradford; Bordey, Angelique F; Gross, Jeffrey B.

2014-01-01

Background Numerous gaseous microemboli (GME) are delivered into the arterial circulation during cardiopulmonary bypass (CPB). These emboli damage end organs through multiple mechanisms that are thought to contribute to neurocognitive deficits following cardiac surgery. Here, we use hypobaric oxygenation to reduce dissolved gases in blood and greatly reduce GME delivery during CPB. Methods Variable subatmospheric pressures were applied to 100% oxygen sweep gas in standard hollow fiber microporous membrane oxygenators to oxygenate and denitrogenate blood. GME were quantified using ultrasound while air embolism from the surgical field was simulated experimentally. We assessed end organ tissues in swine postoperatively using light microscopy. Results Variable sweep gas pressures allowed reliable oxygenation independent of CO2 removal while denitrogenating arterial blood. Hypobaric oxygenation produced dose-dependent reductions of Doppler signals produced by bolus and continuous GME loads in vitro. Swine were maintained using hypobaric oxygenation for four hours on CPB with no apparent adverse events. Compared with current practice standards of O2/air sweep gas, hypobaric oxygenation reduced GME volumes exiting the oxygenator (by 80%), exiting the arterial filter (95%), and arriving at the aortic cannula (∼100%), indicating progressive reabsorption of emboli throughout the CPB circuit in vivo. Analysis of brain tissue suggested decreased microvascular injury under hypobaric conditions. Conclusions Hypobaric oxygenation is an effective, low-cost, common sense approach that capitalizes on the simple physical makeup of GME to achieve their near-total elimination during CPB. This technique holds great potential for limiting end-organ damage and improving outcomes in a variety of patients undergoing extracorporeal circulation. PMID:24206970

A dual sensor for real-time monitoring of glucose and oxygen

PubMed Central

Zhang, Liqiang; Su, Fengyu; Buizer, Sean; Lu, Hongguang; Gao, Weimin; Tian, Yanqing; Meldrum, Deirdre

2013-01-01

A dual glucose and oxygen sensor in a polymer format was developed. The dual sensor composed of a blue emitter as the glucose probe, a red emitter as an oxygen probe, and a yellow emitter as a built-in reference probe which does not respond to either glucose or oxygen. All the three probes were chemically immobilized in a polyacrylamide-based matrix. Therefore, the dual sensor possesses three well separated emission colors and ratiometric approach is applicable for analysis of the glucose and oxygen concentration at biological conditions. The sensor was applied for real-time monitoring of glucose and oxygen consumption of bacterial cells, Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), and mammalian cells of mouse macrophage J774 and human cervical cancer HeLa cell lines. On the other hand, in order to achieve satisfactory sensing performance for glucose, compositions of the matrices among poly(2-hydroxyethyl methacrylate), polyacrylamide, and poly(6-aminohexyl methacrylamide) which is a linker polymer for grafting the glucose probe, were optimized. PMID:24090834

Highly sensitive humidity sensing properties of carbon quantum dots films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xing; Ming, Hai; Liu, Ruihua

2013-02-15

Graphical abstract: Display Omitted Highlights: ► A humidity sensing device was fabricated based on carbon quantum dots (CQDs) films. ► The conductivity of the CQDs films shows a linear and rapid response to atmosphere humidity. ► The humidity sensing property was due to the hydrogen bonds between the functional groups on CQDs. -- Abstract: We reported the fabrication of a humidity sensing device based on carbon quantum dots (CQDs) film. The conductivity of the CQDs film has a linear and rapid response to relative humidity, providing the opportunity for the fabrication of humidity sensing devices. The mechanism of our humiditymore » sensor was proposed to be the formation of hydrogen bonds between carbon quantum dots and water molecules in the humidity environment, which significantly promote the electrons migration. In a control experiment, this hypothesis was confirmed by comparing the humidity sensitivity of candle soot (i.e. carbon nanoparticles) with and without oxygen containing groups on the surfaces.« less

Cerebral arterial gas embolism from attempted mechanical thrombectomy: recovery following hyperbaric oxygen therapy.

PubMed

Segan, Louise; Permezel, Fiona; Ch'ng, Wei; Millar, Ian; Brooks, Mark; Lee-Archer, Matt; Cloud, Geoffrey

2018-04-01

Cerebral arterial gas embolism is a recognised complication of endovascular intervention with an estimated incidence of 0.08%. Its diagnosis is predominantly clinical, supported by neuroimaging. The treatment relies on alleviating mechanical obstruction and reversing the proinflammatory processes that contribute to tissue ischaemia. Hyperbaric oxygen therapy is an effective treatment and has multiple mechanisms to reverse the pathological processes involved in cerebral arterial gas embolism. Symptomatic cerebral arterial gas embolism is a rare complication of endovascular intervention for acute ischaemic stroke. Although there are no previous descriptions of its successful treatment with hyperbaric oxygen therapy following mechanical thrombectomy, this is likely to become more common as mechanical thrombectomy is increasingly used worldwide to treat acute ischaemic stroke. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

[Choice of optimal respiratory support in acute parenchymatous respiratory failure].

PubMed

Cherniĭ, V I; Kuznetsova, I V; Kovalenko, V L

2005-01-01

The principal goals of respiratory therapy for acute respiratory failure are to correct gas exchange and to lower respiratory performance. In acute lung lesion syndrome (ALLS) and acute respiratory distress syndrome (ARDS), the oxygenation index (PaO2/FiO2) reflects the degree of alveolar-capillary membrane damage. The changes in PaO2/FiO2 between 400 to 300 at adequate ventilation can be interpreted as occult alveolar-capillary insufficiency. The principle of power saving in ALLS/ARDS is to choose a respiratory support regimen that may ensure oxygenation safety by eliminating the excess work of respiration. The ratio of PaO2/FiO2/VO2 is proposed to consider to be a criterion for the effectiveness of respiratory support in ALLS/ARDS and a marker of energy deficiency. It has been established that the function of the alveolar-capillary membrane is not impaired with the PaO2/FiO2 ratio of more than 1.5 and the ratio of less than 1.0 is typical of the severe course of the severe course of ARDS and suggests both alveolar-capillary membrane damage and energy deficiency.

Increased oxidative phosphorylation in response to acute and chronic DNA damage

PubMed Central

Brace, Lear E; Vose, Sarah C; Stanya, Kristopher; Gathungu, Rose M; Marur, Vasant R; Longchamp, Alban; Treviño-Villarreal, Humberto; Mejia, Pedro; Vargas, Dorathy; Inouye, Karen; Bronson, Roderick T; Lee, Chih-Hao; Neilan, Edward; Kristal, Bruce S; Mitchell, James R

2016-01-01

Accumulation of DNA damage is intricately linked to aging, aging-related diseases and progeroid syndromes such as Cockayne syndrome (CS). Free radicals from endogenous oxidative energy metabolism can damage DNA, however the potential of acute or chronic DNA damage to modulate cellular and/or organismal energy metabolism remains largely unexplored. We modeled chronic endogenous genotoxic stress using a DNA repair-deficient Csa−/−|Xpa−/− mouse model of CS. Exogenous genotoxic stress was modeled in mice in vivo and primary cells in vitro treated with different genotoxins giving rise to diverse spectrums of lesions, including ultraviolet radiation, intrastrand crosslinking agents and ionizing radiation. Both chronic endogenous and acute exogenous genotoxic stress increased mitochondrial fatty acid oxidation (FAO) on the organismal level, manifested by increased oxygen consumption, reduced respiratory exchange ratio, progressive adipose loss and increased FAO in tissues ex vivo. In multiple primary cell types, the metabolic response to different genotoxins manifested as a cell-autonomous increase in oxidative phosphorylation (OXPHOS) subsequent to a transient decline in steady-state NAD+ and ATP levels, and required the DNA damage sensor PARP-1 and energy-sensing kinase AMPK. We conclude that increased FAO/OXPHOS is a general, beneficial, adaptive response to DNA damage on cellular and organismal levels, illustrating a fundamental link between genotoxic stress and energy metabolism driven by the energetic cost of DNA damage. Our study points to therapeutic opportunities to mitigate detrimental effects of DNA damage on primary cells in the context of radio/chemotherapy or progeroid syndromes. PMID:28721274

Regulatory mechanisms of hemoglobin oxygen affinity in acidosis and alkalosis

PubMed Central

Bellingham, A. J.; Detter, J. C.; Lenfant, C.

1971-01-01

The recent reports of the effect of 2,3-diphosphoglycerate (2,3-DPG) on hemoglobin affinity for oxygen suggested that this substance may play a role in man's adaptation to acidosis and alkalosis. A study of the effect of induced acidosis and alkalosis on the oxyhemoglobin dissociation curve of normal man was therefore carried out, and the mechanisms involved in the physiological regulation of hemoglobin oxygen affinity examined. In acute changes of plasma pH there was no alteration in red cell 2,3-DPG content. However, there were changes in hemoglobin oxygen affinity and these correlated with changes in mean corpuscular hemoglobin concentration (MCHC). With maintained acidosis and alkalosis, red cell 2,3-DPG content was altered and correlated with the changes in hemoglobin oxygen affinity. Both of these mechanisms shift the hemoglobin oxygen dissociation curve opposite to the direct pH (Bohr) effect, and providing the rate of pH change is neither too rapid nor too large, they counteract the direct pH effect and the in vivo hemoglobin oxygen affinity remains unchanged. It is also shown that approximately 35% of the change in hemoglobin oxygen affinity resulting from an alteration in red cell 2,3-DPG, is explained by effect of 2,3-DPG on the red cell pH. PMID:5545127

Phenyl-alpha-tert-butyl nitrone reverses mitochondrial decay in acute Chagas' disease.

PubMed

Wen, Jian-Jun; Bhatia, Vandanajay; Popov, Vsevolod L; Garg, Nisha Jain

2006-12-01

In this study, we investigated the mechanism(s) of mitochondrial functional decline in acute Chagas' disease. Our data show a substantial decline in respiratory complex activities (39 to 58%) and ATP (38%) content in Trypanosoma cruzi-infected murine hearts compared with normal controls. These metabolic alterations were associated with an approximately fivefold increase in mitochondrial reactive oxygen species production rate, substantial oxidative insult of mitochondrial membranes and respiratory complex subunits, and >60% inhibition of mtDNA-encoded transcripts for respiratory complex subunits in infected myocardium. The antioxidant phenyl-alpha-tert-butyl nitrone (PBN) arrested the oxidative damage-mediated loss in mitochondrial membrane integrity, preserved redox potential-coupled mitochondrial gene expression, and improved respiratory complex activities (47 to 95% increase) and cardiac ATP level (>or=40% increase) in infected myocardium. Importantly, PBN resulted twofold decline in mitochondrial reactive oxygen species production rate in infected myocardium. Taken together, our data demonstrate the pathological significance of oxidative stress in metabolic decay and energy homeostasis in acute chagasic myocarditis and further suggest that oxidative injuries affecting mitochondrial integrity-dependent expression and activity of the respiratory complexes initiate a feedback cycle of electron transport chain inefficiency, increased reactive oxygen species production, and energy homeostasis in acute chagasic hearts. PBN and other mitochondria-targeted antioxidants may be useful in altering mitochondrial decay and oxidative pathology in Chagas' disease.

Regulation of iron transport systems in Enterobacteriaceae in response to oxygen and iron availability.

PubMed

Carpenter, Chandra; Payne, Shelley M

2014-04-01

Iron is an essential nutrient for most bacteria. Depending on the oxygen available in the surrounding environment, iron is found in two distinct forms: ferrous (Fe(II)) or ferric (Fe(III)). Bacteria utilize different transport systems for the uptake of the two different forms of iron. In oxic growth conditions, iron is found in its insoluble, ferric form, and in anoxic growth conditions iron is found in its soluble, ferrous form. Enterobacteriaceae have adapted to transporting the two forms of iron by utilizing the global, oxygen-sensing regulators, ArcA and Fnr to regulate iron transport genes in response to oxygen. Copyright © 2014 Elsevier Inc. All rights reserved.

A role for haemolymph oxygen capacity in heat tolerance of eurythermal crabs

PubMed Central

Giomi, Folco; Pörtner, Hans-Otto

2013-01-01

Heat tolerance in aquatic ectotherms is constrained by a mismatch, occurring at high temperatures, between oxygen delivery and demand which compromises the maintenance of aerobic scope. The present study analyses how the wide thermal tolerance range of an eurythermal model species, the green crab Carcinus maenas is supported and limited by its ability to sustain efficient oxygen transport to tissues. Similar to other eurytherms, C. maenas sustains naturally occurring acute warming events through the integrated response of circulatory and respiratory systems. The response of C. maenas to warming can be characterized by two phases. During initial warming, oxygen consumption and heart rate increase, while stroke volume and haemolymph oxygen partial pressure decrease. During further warming, dissolved oxygen levels in the venous compartment decrease below the threshold of full haemocyanin oxygen saturation. The progressive release of haemocyanin bound oxygen with further warming follows an exponential pattern, thereby saving energy in oxygen transport and causing an associated leveling off of metabolic rate. According to the concept of oxygen and capacity limited thermal tolerance (OCLTT), this indicates that the thermal tolerance window is widened by the increasing contribution of haemocyanin oxygen transport and associated energy savings in cardiocirculation. Haemocyanin bound oxygen sustains cardiac performance to cover the temperature range experienced by C. maenas in the field. To our knowledge this is the first study providing evidence of a relationship between thermal tolerance and blood (haemolymph) oxygen transport in a eurythermal invertebrate. PMID:23720633

A role for haemolymph oxygen capacity in heat tolerance of eurythermal crabs.

PubMed

Giomi, Folco; Pörtner, Hans-Otto

2013-01-01

Heat tolerance in aquatic ectotherms is constrained by a mismatch, occurring at high temperatures, between oxygen delivery and demand which compromises the maintenance of aerobic scope. The present study analyses how the wide thermal tolerance range of an eurythermal model species, the green crab Carcinus maenas is supported and limited by its ability to sustain efficient oxygen transport to tissues. Similar to other eurytherms, C. maenas sustains naturally occurring acute warming events through the integrated response of circulatory and respiratory systems. The response of C. maenas to warming can be characterized by two phases. During initial warming, oxygen consumption and heart rate increase, while stroke volume and haemolymph oxygen partial pressure decrease. During further warming, dissolved oxygen levels in the venous compartment decrease below the threshold of full haemocyanin oxygen saturation. The progressive release of haemocyanin bound oxygen with further warming follows an exponential pattern, thereby saving energy in oxygen transport and causing an associated leveling off of metabolic rate. According to the concept of oxygen and capacity limited thermal tolerance (OCLTT), this indicates that the thermal tolerance window is widened by the increasing contribution of haemocyanin oxygen transport and associated energy savings in cardiocirculation. Haemocyanin bound oxygen sustains cardiac performance to cover the temperature range experienced by C. maenas in the field. To our knowledge this is the first study providing evidence of a relationship between thermal tolerance and blood (haemolymph) oxygen transport in a eurythermal invertebrate.

Oceanographic and biological effects of shoaling of the oxygen minimum zone.

PubMed

Gilly, William F; Beman, J Michael; Litvin, Steven Y; Robison, Bruce H

2013-01-01

Long-term declines in oxygen concentrations are evident throughout much of the ocean interior and are particularly acute in midwater oxygen minimum zones (OMZs). These regions are defined by extremely low oxygen concentrations (<20-45 μmol kg(-1)), cover wide expanses of the ocean, and are associated with productive oceanic and coastal regions. OMZs have expanded over the past 50 years, and this expansion is predicted to continue as the climate warms worldwide. Shoaling of the upper boundaries of the OMZs accompanies OMZ expansion, and decreased oxygen at shallower depths can affect all marine organisms through multiple direct and indirect mechanisms. Effects include altered microbial processes that produce and consume key nutrients and gases, changes in predator-prey dynamics, and shifts in the abundance and accessibility of commercially fished species. Although many species will be negatively affected by these effects, others may expand their range or exploit new niches. OMZ shoaling is thus likely to have major and far-reaching consequences.

Peroxide-based oxygen generating topical wound dressing for enhancing healing of dermal wounds.

PubMed

Chandra, Prafulla K; Ross, Christina L; Smith, Leona C; Jeong, Seon S; Kim, Jaehyun; Yoo, James J; Harrison, Benjamin S

2015-01-01

Oxygen generating biomaterials represent a new trend in regenerative medicine that aims to generate and supply oxygen at the site of requirement, to support tissue healing and regeneration. To enhance the healing of dermal wounds, we have developed a highly portable, in situ oxygen generating wound dressings that uses sodium percarbonate (SPO) and calcium peroxide (CPO) as chemical oxygen sources. The dressing continuously generated oxygen for more than 3 days, after which it was replaced. In the in vivo testing on porcine full-thickness porcine wound model, the SPO/CPO dressing showed enhanced wound healing during the 8 week study period. Quantitative measurements of wound healing related parameters, such as wound closure, reepithelialization, epidermal thickness and collagen content of dermis showed that supplying oxygen topically using the SPO/CPO dressing significantly accelerated the wound healing. An increase in neovascularization, as determined using Von Willebrand factor (vWF) and CD31 staining, was also observed in the presence of SPO/CPO dressing. This novel design for a wound dressing that contains oxygen generating biomaterials (SPO/CPO) for supplying topical oxygen, may find utility in treating various types of acute to chronic wounds. © 2015 by the Wound Healing Society.

Nanocomposite thin films for optical gas sensing

DOEpatents

Ohodnicki, Paul R; Brown, Thomas D

2014-06-03

The disclosure relates to a plasmon resonance-based method for gas sensing in a gas stream utilizing a gas sensing material. In an embodiment the gas stream has a temperature greater than about 500.degree. C. The gas sensing material is comprised of gold nanoparticles having an average nanoparticle diameter of less than about 100 nanometers dispersed in an inert matrix having a bandgap greater than or equal to 5 eV, and an oxygen ion conductivity less than approximately 10.sup.-7 S/cm at a temperature of 700.degree. C. Exemplary inert matrix materials include SiO.sub.2, Al.sub.2O.sub.3, and Si.sub.3N.sub.4 as well as modifications to modify the effective refractive indices through combinations and/or doping of such materials. Changes in the chemical composition of the gas stream are detected by changes in the plasmon resonance peak. The method disclosed offers significant advantage over active and reducible matrix materials typically utilized, such as yttria-stabilized zirconia (YSZ) or TiO.sub.2.

Combined application of dexamethasone and hyperbaric oxygen therapy yields better efficacy for patients with delayed encephalopathy after acute carbon monoxide poisoning.

PubMed

Xiang, Wenping; Xue, Hui; Wang, Baojun; Li, Yuechun; Zhang, Jun; Jiang, Changchun; Liang, Furu; Pang, Jiangxia; Yu, Lehua

2017-01-01

Delayed encephalopathy after acute carbon monoxide (CO) poisoning (DEACMP) commonly occurs after recovering from acute CO poisoning. This study was performed to assess the efficacy of the combined application of dexamethasone and hyperbaric oxygen (HBO) therapy in patients with DEACMP. A total of 120 patients with DEACMP were recruited and randomly assigned into the experimental group (receiving dexamethasone 5 mg/day or 10 mg/day plus HBO therapy) and control group (HBO therapy as monotherapy). Meanwhile, the conventional treatments were provided for all the patients. We used the Mini-Mental State Examination (MMSE) scale to assess the cognitive function, the National Institutes of Health Stroke Scale (NIHSS) to assess the neurological function and the remission rate (RR) to assess the clinical efficacy. Myelin basic protein (MBP) in the cerebrospinal fluid (CSF) was also measured. After 4 weeks of treatment, compared to the control group, the experimental group had a significantly higher remission rate ( P =0.032), a significantly higher average MMSE score ( P =0.037) and a significantly lower average NIHSS score ( P =0.002). Meanwhile, there was a trend toward better improvement with dexamethasone 10 mg/day, and the level of MBP in the CSF of patients was significantly lower in the experimental group than in the control group ( P <0.0001). The addition of dexamethasone did not significantly increase the incidence of adverse events. These results indicate that the combined application of dexamethasone and HBO therapy could yield better efficacy for patients with DEACMP and should be viewed as a potential new therapy.

Erythrocytes Are Oxygen-Sensing Regulators of the Cerebral Microcirculation.

PubMed

Wei, Helen Shinru; Kang, Hongyi; Rasheed, Izad-Yar Daniel; Zhou, Sitong; Lou, Nanhong; Gershteyn, Anna; McConnell, Evan Daniel; Wang, Yixuan; Richardson, Kristopher Emil; Palmer, Andre Francis; Xu, Chris; Wan, Jiandi; Nedergaard, Maiken

2016-08-17

Energy production in the brain depends almost exclusively on oxidative metabolism. Neurons have small energy reserves and require a continuous supply of oxygen (O2). It is therefore not surprising that one of the hallmarks of normal brain function is the tight coupling between cerebral blood flow and neuronal activity. Since capillaries are embedded in the O2-consuming neuropil, we have here examined whether activity-dependent dips in O2 tension drive capillary hyperemia. In vivo analyses showed that transient dips in tissue O2 tension elicit capillary hyperemia. Ex vivo experiments revealed that red blood cells (RBCs) themselves act as O2 sensors that autonomously regulate their own deformability and thereby flow velocity through capillaries in response to physiological decreases in O2 tension. This observation has broad implications for understanding how local changes in blood flow are coupled to synaptic transmission. Copyright © 2016 Elsevier Inc. All rights reserved.

No effect of acute beetroot juice ingestion on oxygen consumption, glucose kinetics, or skeletal muscle metabolism during submaximal exercise in males.

PubMed

Betteridge, Scott; Bescós, Raúl; Martorell, Miquel; Pons, Antoni; Garnham, Andrew P; Stathis, Christos C; McConell, Glenn K

2016-02-15

Beetroot juice, which is rich in nitrate (NO3 (-)), has been shown in some studies to decrease oxygen consumption (V̇o2) for a given exercise workload, i.e., increasing efficiency and exercise tolerance. Few studies have examined the effect of beetroot juice or nitrate supplementation on exercise metabolism. Eight healthy recreationally active males participated in three trials involving ingestion of either beetroot juice (Beet; ∼8 mmol NO3 (-)), Placebo (nitrate-depleted Beet), or Beet + mouthwash (Beet+MW), all of which were performed in a randomized single-blind crossover design. Two-and-a-half hours later, participants cycled for 60 min on an ergometer at 65% of V̇o2 peak. [6,6-(2)H]glucose was infused to determine glucose kinetics, blood samples obtained throughout exercise, and skeletal muscle biopsies that were obtained pre- and postexercise. Plasma nitrite [NO2 (-)] increased significantly (∼130%) with Beet, and this was attenuated in MW+Beet. Beet and Beet+MW had no significant effect on oxygen consumption, blood glucose, blood lactate, plasma nonesterified fatty acids, or plasma insulin during exercise. Beet and Beet+MW also had no significant effect on the increase in glucose disposal during exercise. In addition, Beet and Beet+MW had no significant effect on the decrease in muscle glycogen and phosphocreatine and the increase in muscle creatine, lactate, and phosphorylated acetyl CoA carboxylase during exercise. In conclusion, at the dose used, acute ingestion of beetroot juice had little effect on skeletal muscle metabolism during exercise. Copyright © 2016 the American Physiological Society.

Minimizing ATP depletion by oxygen scavengers for single-molecule fluorescence imaging in live cells.

PubMed

Jung, Seung-Ryoung; Deng, Yi; Kushmerick, Christopher; Asbury, Charles L; Hille, Bertil; Koh, Duk-Su

2018-06-19

The stability of organic dyes against photobleaching is critical in single-molecule tracking and localization microscopy. Since oxygen accelerates photobleaching of most organic dyes, glucose oxidase is commonly used to slow dye photobleaching by depleting oxygen. As demonstrated here, pyranose-2-oxidase slows bleaching of Alexa647 dye by ∼20-fold. However, oxygen deprivation may pose severe problems for live cells by reducing mitochondrial oxidative phosphorylation and ATP production. We formulate a method to sustain intracellular ATP levels in the presence of oxygen scavengers. Supplementation with metabolic intermediates including glyceraldehyde, glutamine, and α-ketoisocaproate maintained the intracellular ATP level for at least 10 min by balancing between FADH 2 and NADH despite reduced oxygen levels. Furthermore, those metabolites supported ATP-dependent synthesis of phosphatidylinositol 4,5-bisphosphate and internalization of PAR2 receptors. Our method is potentially relevant to other circumstances that involve acute drops of oxygen levels, such as ischemic damage in the brain or heart or tissues for transplantation.

Amperometric Solid Electrolyte Oxygen Microsensors with Easy Batch Fabrication

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Xu, Jennifer C.; Liu, ChungChiun

2011-01-01

An amperometric solid electrolyte oxygen (O2) microsensor using a novel and robust structure has been developed with a detection range of 0.025 to 21 percent of O2 concentration. The microsensor has a simple structure with a sensing area of 1.10 0.99 mm(exp 2), and is operated by applying voltage across the electrodes and measuring the resulting current flow at a temperature of 600 C.

Fetal circulatory responses to oxygen lack.

PubMed

Jensen, A; Berger, R

1991-10-01

The knowledge on fetal and neonatal circulatory physiology accumulated by basic scientists and clinicians over the years has contributed considerably to the recent decline of perinatal morbidity and mortality. This review will summarize the peculiarities of the fetal circulation, the distribution of organ blood flow during normoxemia, and that during oxygen lack caused by various experimental perturbations. Furthermore, the relation between oxygen delivery and tissue metabolism during oxygen lack as well as evidence to support a new concept will be presented along with the principal cardiovascular mechanisms involved. Finally, blood flow and oxygen delivery to the principal fetal organs will be examined and discussed in relation to organ function. The fetal circulatory response to hypoxemia and asphyxia is a centralization of blood flow in favour of the brain, heart, and adrenals and at the expense of almost all peripheral organs, particularly of the lungs, carcass, skin and scalp. This response is qualitatively similar but quantitatively different under various experimental conditions. However, at the nadir of severe acute asphyxia the circulatory centralization cannot be maintained. Then there is circulatory decentralization, and the fetus will experience severe brain damage if not expire unless immediate resuscitation occurs. Future work in this field will have to concentrate on the important questions, what factors determine this collapse of circulatory compensating mechanisms in the fetus, how does it relate to neuronal damage, and how can the fetal brain be pharmacologically protected against the adverse effects of asphyxia.

Oxygen, the lung and the diver: friends and foes?

PubMed

van Ooij, Pieter-Jan A M; Sterk, Peter J; van Hulst, Robert A

2016-12-01

Worldwide, the number of professional and sports divers is increasing. Most of them breathe diving gases with a raised partial pressure of oxygen (P O 2 ). However, if the P O 2 is between 50 and 300 kPa (375-2250 mmHg) (hyperoxia), pathological pulmonary changes can develop, known as pulmonary oxygen toxicity (POT). Although in its acute phase, POT is reversible, it can ultimately lead to non-reversible pathological changes. Therefore, it is important to monitor these divers to prevent them from sustaining irreversible lesions.This review summarises the pulmonary pathophysiological effects when breathing oxygen with a P O 2 of 50-300 kPa (375-2250 mmHg). We describe the role and the limitations of lung function testing in monitoring the onset and development of POT, and discuss new techniques in respiratory medicine as potential markers in the early development of POT in divers. Copyright ©ERS 2016.

Direct tissue oxygen monitoring by in vivo photoacoustic lifetime imaging (PALI)

NASA Astrophysics Data System (ADS)

Shao, Qi; Morgounova, Ekaterina; Ashkenazi, Shai

2014-03-01

Tissue oxygen plays a critical role in maintaining tissue viability and in various diseases, including response to therapy. Images of oxygen distribution provide the history of tissue hypoxia and evidence of oxygen availability in the circulatory system. Currently available methods of direct measuring or imaging tissue oxygen all have significant limitations. Previously, we have reported a non-invasive in vivo imaging modality based on photoacoustic lifetime. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflects the spatial and temporal distribution of tissue oxygen. We have applied PALI on tumor hypoxia in small animals, and the hypoxic region imaged by PALI is consistent with the site of the tumor imaged by ultrasound. Here, we present two studies of applying PALI to monitor changes of tissue oxygen by modulations. The first study involves an acute ischemia model using a thin thread tied around the hind limb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of muscle pO2 and recovery from hypoxia due to reperfusion were observed by PALI tracking the same region. The second study modulates tissue oxygen by controlling the percentage of oxygen the mouse inhales. We demonstrate that PALI is able to reflect the change of oxygen level with respect to both hyperbaric and hypobaric conditions. We expect this technique to be very attractive for a range of clinical applications in which tissue oxygen mapping would improve therapy decision making and treatment planning.

Contribution of blood oxygen and carbon dioxide sensing to the energetic optimization of human walking.

PubMed

Wong, Jeremy D; O'Connor, Shawn M; Selinger, Jessica C; Donelan, J Maxwell

2017-08-01

People can adapt their gait to minimize energetic cost, indicating that walking's neural control has access to ongoing measurements of the body's energy use. In this study we tested the hypothesis that an important source of energetic cost measurements arises from blood gas receptors that are sensitive to O 2 and CO 2 concentrations. These receptors are known to play a role in regulating other physiological processes related to energy consumption, such as ventilation rate. Given the role of O 2 and CO 2 in oxidative metabolism, sensing their levels can provide an accurate estimate of the body's total energy use. To test our hypothesis, we simulated an added energetic cost for blood gas receptors that depended on a subject's step frequency and determined if subjects changed their behavior in response to this simulated cost. These energetic costs were simulated by controlling inspired gas concentrations to decrease the circulating levels of O 2 and increase CO 2 We found this blood gas control to be effective at shifting the step frequency that minimized the ventilation rate and perceived exertion away from the normally preferred frequency, indicating that these receptors provide the nervous system with strong physiological and psychological signals. However, rather than adapt their preferred step frequency toward these lower simulated costs, subjects persevered at their normally preferred frequency even after extensive experience with the new simulated costs. These results suggest that blood gas receptors play a negligible role in sensing energetic cost for the purpose of optimizing gait. NEW & NOTEWORTHY Human gait adaptation implies that the nervous system senses energetic cost, yet this signal is unknown. We tested the hypothesis that the blood gas receptors sense cost for gait optimization by controlling blood O 2 and CO 2 with step frequency as people walked. At the simulated energetic minimum, ventilation and perceived exertion were lowest, yet subjects

The polycystins are modulated by cellular oxygen-sensing pathways and regulate mitochondrial function

PubMed Central

Padovano, Valeria; Kuo, Ivana Y.; Stavola, Lindsey K.; Aerni, Hans R.; Flaherty, Benjamin J.; Chapin, Hannah C.; Ma, Ming; Somlo, Stefan; Boletta, Alessandra; Ehrlich, Barbara E.; Rinehart, Jesse; Caplan, Michael J.

2017-01-01

Autosomal dominant polycystic kidney disease is caused by mutations in the genes encoding polycystin-1 (PC1) and polycystin-2 (PC2), which form an ion channel complex that may mediate ciliary sensory processes and regulate endoplasmic reticulum (ER) Ca2+ release. Loss of PC1 expression profoundly alters cellular energy metabolism. The mechanisms that control the trafficking of PC1 and PC2, as well as their broader physiological roles, are poorly understood. We found that O2 levels regulate the subcellular localization and channel activity of the polycystin complex through its interaction with the O2-sensing prolyl hydroxylase domain containing protein EGLN3 (or PHD3), which hydroxylates PC1. Moreover, cells lacking PC1 expression use less O2 and show less mitochondrial Ca2+ uptake in response to bradykinin-induced ER Ca2+ release, indicating that PC1 can modulate mitochondrial function. These data suggest a novel role for the polycystins in sensing and responding to cellular O2 levels. PMID:27881662

Space Shuttle Orbiter oxygen partial pressure sensing and control system improvements

NASA Technical Reports Server (NTRS)

Frampton, Robert F.; Hoy, Dennis M.; Kelly, Kevin J.; Walleshauser, James J.

1992-01-01

A program aimed at developing a new PPO2 oxygen sensor and a replacement amplifier for the Space Shuttle Orbiter is described. Experimental design methodologies used in the test and modeling process made it possible to enhance the effectiveness of the program and to reduce its cost. Significant cost savings are due to the increased lifetime of the basic sensor cell, the maximization of useful sensor life through an increased amplifier gain adjustment capability, the use of streamlined production processes for the manufacture of the assemblies, and the refurbishment capability of the replacement sensor.

Oxygen sensitivity of mitochondrial function in rat arterial chemoreceptor cells

PubMed Central

Buckler, Keith J; Turner, Philip J

2013-01-01

The mechanism of oxygen sensing in arterial chemoreceptors is unknown but has often been linked to mitochondrial function. A common criticism of this hypothesis is that mitochondrial function is insensitive to physiological levels of hypoxia. Here we investigate the effects of hypoxia (down to 0.5% O2) on mitochondrial function in neonatal rat type-1 cells. The oxygen sensitivity of mitochondrial [NADH] was assessed by monitoring autofluorescence and increased in hypoxia with a P50 of 15 mm Hg (1 mm Hg = 133.3 Pa) in normal Tyrode or 46 mm Hg in Ca2+-free Tyrode. Hypoxia also depolarised mitochondrial membrane potential (ψm, measured using rhodamine 123) with a P50 of 3.1, 3.3 and 2.8 mm Hg in normal Tyrode, Ca2+-free Tyrode and Tyrode containing the Ca2+ channel antagonist Ni2+, respectively. In the presence of oligomycin and low carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP; 75 nm) ψm is maintained by electron transport working against an artificial proton leak. Under these conditions hypoxia depolarised ψm/inhibited electron transport with a P50 of 5.4 mm Hg. The effects of hypoxia upon cytochrome oxidase activity were investigated using rotenone, myxothiazol, antimycin A, oligomycin, ascorbate and the electron donor tetramethyl-p-phenylenediamine. Under these conditions ψm is maintained by complex IV activity alone. Hypoxia inhibited cytochrome oxidase activity (depolarised ψm) with a P50 of 2.6 mm Hg. In contrast hypoxia had little or no effect upon NADH (P50= 0.3 mm Hg), electron transport or cytochrome oxidase activity in sympathetic neurons. In summary, type-1 cell mitochondria display extraordinary oxygen sensitivity commensurate with a role in oxygen sensing. The reasons for this highly unusual behaviour are as yet unexplained. PMID:23671162

LUMOS - A Sensitive and Reliable Optode System for Measuring Dissolved Oxygen in the Nanomolar Range

PubMed Central

Lehner, Philipp; Larndorfer, Christoph; Garcia-Robledo, Emilio; Larsen, Morten; Borisov, Sergey M.; Revsbech, Niels-Peter; Glud, Ronnie N.; Canfield, Donald E.; Klimant, Ingo

2015-01-01

Most commercially available optical oxygen sensors target the measuring range of 300 to 2 μmol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized “sensing chemistry” that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded in a Hyflon AD 60 polymer matrix and has a KSV of 6.25 x 10-3 ppmv-1. The applicable measurement range is from 1000 nM down to a detection limit of 0.5 nM. A second sensor material based on the platinum(II) analogue of the porphyrin is spectrally compatible with the readout device and has a measurement range of 20 μM down to 10 nM. The LUMOS device is a dedicated system optimized for a high signal to noise ratio, but in principle any phase flourimeter can be adapted to act as a readout device for the highly sensitive and robust sensing chemistry. Vise versa, the LUMOS fluorimeter can be used for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used to measure nanomolar oxygen concentrations. Oxygen contamination in common sample containers has been investigated and microbial or enzymatic oxygen consumption at nanomolar concentrations is presented. PMID:26029920

Gas-Sensing Characteristics of SrFeO3-δ Thin Film Probed by a Homemade Apparatus

NASA Astrophysics Data System (ADS)

Manikandan, M.; Santhosh Kumar, B.; Mukil Raj, T.; Moorthy Babu, S.; Venkateswaran, C.

2018-05-01

SrFeO2.97 phase obtained by annealing radiofrequency-sputtered stoichiometric film at 600°C for 24 h has been tested using a homemade apparatus coupled with impedance spectrometry. Oxygen nonstoichiometry plays a vital role in sensing of reducing gases. Hence, this phase showed efficient sensing performance for different reducing gases such as acetone (CH3COCH3), ethanol (C2H5OH), ammonia (NH3), and hydrogen sulfide (H2S), with high sensing response recorded for H2S gas at 60°C.

Tracking the Oxygen Status in the Cell Nucleus with a Hoechst-Tagged Phosphorescent Ruthenium Complex.

PubMed

Hara, Daiki; Umehara, Yui; Son, Aoi; Asahi, Wataru; Misu, Sotaro; Kurihara, Ryohsuke; Kondo, Teruyuki; Tanabe, Kazuhito

2018-05-04

Molecular oxygen in living cells is distributed and consumed inhomogeneously, depending on the activity of each organelle. Therefore, tractable methods that can be used to monitor the oxygen status in each organelle are needed to understand cellular function. Here we report the design of a new oxygen-sensing probe for use in the cell nucleus. We prepared "Ru-Hoechsts", each consisting of a phosphorescent ruthenium complex linked to a Hoechst 33258 moiety, and characterized their properties as oxygen sensors. The Hoechst unit shows strong DNA-binding properties in the nucleus, and the ruthenium complex shows oxygen-dependent phosphorescence. Thus, Ru-Hoechsts accumulated in the cell nucleus and showed oxygen-dependent signals that could be monitored. Of the Ru-Hoechsts prepared in this study, Ru-Hoechst b, in which the ruthenium complex and the Hoechst unit were linked through a hexyl chain, showed the most suitable properties for monitoring the oxygen status. Ru-Hoechsts are probes with high potential for visualizing oxygen fluctuations in the nucleus. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High Oxygen Partial Pressure Decreases Anemia-Induced Heart Rate Increase Equivalent to Transfusion

PubMed Central

Feiner, John R.; Finlay-Morreale, Heather E.; Toy, Pearl; Lieberman, Jeremy A.; Viele, Maurene K.; Hopf, Harriet W.; Weiskopf, Richard B.

2011-01-01

Background Anemia is associated with morbidity and mortality and frequently leads to transfusion of erythrocytes. We sought to compare directly the effect of high inspired oxygen fraction vs. transfusion of erythrocytes on the anemia-induced increased heart rate (HR) in humans undergoing experimental acute isovolemic anemia. Methods We combined HR data from healthy subjects undergoing experimental isovolemic anemia in seven studies performed by our group. We examined HR changes associated with breathing 100% oxygen by non-rebreathing face mask vs. transfusion of erythrocytes at their nadir hemoglobin (Hb) concentration of 5 g/dL. Data were analyzed using a mixed-effects model. Results HR had an inverse linear relationship to hemoglobin concentration with a mean increase of 3.9 beats per minute per gram of Hb (beats/min/g Hb) decrease (95% confidence interval [CI], 3.7 – 4.1 beats/min/g Hb), P < 0.0001. Return of autologous erythrocytes significantly decreased HR by 5.3 beats/min/g Hb (95% CI, 3.8 – 6.8 beats/min/g Hb) increase, P < 0.0001. HR at nadir Hb of 5.6 g/dL (95% CI, 5.5 – 5.7 g/dL) when breathing air (91.4 beats/min; 95% CI, 87.6 – 95.2 beats/min) was reduced by breathing 100% oxygen (83.0 beats/min; 95% CI, 79.0 -87.0 beats/min), P < 0.0001. The HR at hemoglobin 5.6 g/dL when breathing oxygen was equivalent to the HR at Hb 8.9 g/dL when breathing air. Conclusions High arterial oxygen partial pressure reverses the heart rate response to anemia, probably owing to its usability, rather than its effect on total oxygen content. The benefit of high arterial oxygen partial pressure has significant potential clinical implications for the acute treatment of anemia and results of transfusion trials. PMID:21768873

Characterisation of putative oxygen chemoreceptors in bowfin (Amia calva).

PubMed

Porteus, Cosima S; Wright, Patricia A; Milsom, William K

2014-04-15

Serotonin containing neuroepithelial cells (NECs) are putative oxygen sensing cells found in different locations within the gills of fish. In this study we wished to determine the effect of sustained internal (blood) hypoxaemia versus external (aquatic) hypoxia on the size and density of NECs in the first gill arch of bowfin (Amia calva), a facultative air breather. We identified five different populations of serotonergic NECs in this species (Types I-V) based on location, presence of synaptic vesicles (SV) that stain for the antibody SV2, innervation and labelling with the neural crest marker HNK-1. Cell Types I-III were innervated, and these cells, which participate in central O2 chemoreflexes, were studied further. Although there was no change in the density of any cell type in bowfin after exposure to sustained hypoxia (6.0 kPa for 7 days) without access to air, all three of these cell types increased in size. In contrast, only Type II and III cells increased in size in bowfin exposed to sustained hypoxia with access to air. These data support the suggestion that NECs are putative oxygen-sensing cells, that they occur in several locations, and that Type I cells monitor only hypoxaemia, whereas both other cell types monitor hypoxia and hypoxaemia.

Studies on the temperature distribution of a thick film transcutaneous oxygen sensor and its thermal influences on oxygen measurement.

PubMed

Lam, Liza; Bilek, Jaromir; Atkinson, John

2006-11-01

The partial pressures of gases, namely oxygen and carbon dioxide, in the arterial blood are important parameters for doctors to determine the respiratory conditions of patients. Currently in practice, there are a number of ways to measure these parameters, one of which is transcutaneous blood gas monitoring. This technique is a popular noninvasive measurement method for obtaining fast and relatively accurate responses. In this investigation, thick film technology has been employed to develop an amperometric oxygen sensor which consists of a heating module to elevate the temperature at the skin surface to transcutaneous levels. The heating module includes a heating element and its temperature is regulated by a temperature control circuit. Using an infrared camera, the transient and steady-state temperature distributions as well as the stability of the heating element have been analysed. The influence of temperature on the oxygen sensing module is also studied. In addition, a three-dimensional theoretical model is established to evaluate the thermal response of the sensor and subsequently compared with the results from the practical prototype. With this model, the design stages can be simplified and future heating modules for transcutaneous sensors could be generated and improved more easily and effectively.

'That doesn't translate': the role of evidence-based practice in disempowering speech pathologists in acute aphasia management.

PubMed

Foster, Abby; Worrall, Linda; Rose, Miranda; O'Halloran, Robyn

2015-07-01

An evidence-practice gap has been identified in current acute aphasia management practice, with the provision of services to people with aphasia in the acute hospital widely considered in the literature to be inconsistent with best-practice recommendations. The reasons for this evidence-practice gap are unclear; however, speech pathologists practising in this setting have articulated a sense of dissonance regarding their limited service provision to this population. A clearer understanding of why this evidence-practice gap exists is essential in order to support and promote evidence-based approaches to the care of people with aphasia in acute care settings. To provide an understanding of speech pathologists' conceptualization of evidence-based practice for acute post-stroke aphasia, and its implementation. This study adopted a phenomenological approach, underpinned by a social constructivist paradigm. In-depth interviews were conducted with 14 Australian speech pathologists, recruited using a purposive sampling technique. An inductive thematic analysis of the data was undertaken. A single, overarching theme emerged from the data. Speech pathologists demonstrated a sense of disempowerment as a result of their relationship with evidence-based practice for acute aphasia management. Three subthemes contributed to this theme. The first described a restricted conceptualization of evidence-based practice. The second revealed speech pathologists' strained relationships with the research literature. The third elucidated a sense of professional unease over their perceived inability to enact evidence-based clinical recommendations, despite their desire to do so. Speech pathologists identified a current knowledge-practice gap in their management of aphasia in acute hospital settings. Speech pathologists place significant emphasis on the research evidence; however, their engagement with the research is limited, in part because it is perceived to lack clinical utility. A sense

Perfluorocarbon Enhanced Glasgow Oxygen Level Dependent (GOLD) Magnetic Resonance Metabolic Imaging Identifies the Penumbra Following Acute Ischemic Stroke

PubMed Central

Deuchar, Graeme A; Brennan, David; Holmes, William M; Shaw, Martin; Macrae, I Mhairi; Santosh, Celestine

2018-01-01

The ability to identify metabolically active and potentially salvageable ischaemic penumbra is crucial for improving treatment decisions in acute stroke patients. Our solution involves two complementary novel MRI techniques (Glasgow Oxygen Level Dependant (GOLD) Metabolic Imaging), which when combined with a perfluorocarbon (PFC) based oxygen carrier and hyperoxia can identify penumbra due to dynamic changes related to continued metabolism within this tissue compartment. Our aims were (i) to investigate whether PFC offers similar enhancement of the second technique (Lactate Change) as previously demonstrated for the T2*OC technique (ii) to demonstrate both GOLD metabolic imaging techniques working concurrently to identify penumbra, following administration of Oxycyte® (O-PFC) with hyperoxia. Methods: An established rat stroke model was utilised. Part-1: Following either saline or PFC, magnetic resonance spectroscopy was applied to investigate the effect of hyperoxia on lactate change in presumed penumbra. Part-2; rats received O-PFC prior to T2*OC (technique 1) and MR spectroscopic imaging, which was used to identify regions of tissue lactate change (technique 2) in response to hyperoxia. In order to validate the techniques, imaging was followed by [14C]2-deoxyglucose autoradiography to correlate tissue metabolic status to areas identified as penumbra. Results: Part-1: PFC+hyperoxia resulted in an enhanced reduction of lactate in the penumbra when compared to saline+hyperoxia. Part-2: Regions of brain tissue identified as potential penumbra by both GOLD metabolic imaging techniques utilising O-PFC, demonstrated maintained glucose metabolism as compared to adjacent core tissue. Conclusion: For the first time in vivo, enhancement of both GOLD metabolic imaging techniques has been demonstrated following intravenous O-PFC+hyperoxia to identify ischaemic penumbra. We have also presented preliminary evidence of the potential therapeutic benefit offered by O-PFC. These

Fractal Dimension of EEG Activity Senses Neuronal Impairment in Acute Stroke

PubMed Central

Zappasodi, Filippo; Olejarczyk, Elzbieta; Marzetti, Laura; Assenza, Giovanni; Pizzella, Vittorio; Tecchio, Franca

2014-01-01

The brain is a self-organizing system which displays self-similarities at different spatial and temporal scales. Thus, the complexity of its dynamics, associated to efficient processing and functional advantages, is expected to be captured by a measure of its scale-free (fractal) properties. Under the hypothesis that the fractal dimension (FD) of the electroencephalographic signal (EEG) is optimally sensitive to the neuronal dysfunction secondary to a brain lesion, we tested the FD’s ability in assessing two key processes in acute stroke: the clinical impairment and the recovery prognosis. Resting EEG was collected in 36 patients 4–10 days after a unilateral ischemic stroke in the middle cerebral artery territory and 19 healthy controls. National Health Institute Stroke Scale (NIHss) was collected at T0 and 6 months later. Highuchi FD, its inter-hemispheric asymmetry (FDasy) and spectral band powers were calculated for EEG signals. FD was smaller in patients than in controls (1.447±0.092 vs 1.525±0.105) and its reduction was paired to a worse acute clinical status. FD decrease was associated to alpha increase and beta decrease of oscillatory activity power. Larger FDasy in acute phase was paired to a worse clinical recovery at six months. FD in our patients captured the loss of complexity reflecting the global system dysfunction resulting from the structural damage. This decrease seems to reveal the intimate nature of structure-function unity, where the regional neural multi-scale self-similar activity is impaired by the anatomical lesion. This picture is coherent with neuronal activity complexity decrease paired to a reduced repertoire of functional abilities. FDasy result highlights the functional relevance of the balance between homologous brain structures’ activities in stroke recovery. PMID:24967904

Fractal dimension of EEG activity senses neuronal impairment in acute stroke.

PubMed

Zappasodi, Filippo; Olejarczyk, Elzbieta; Marzetti, Laura; Assenza, Giovanni; Pizzella, Vittorio; Tecchio, Franca

2014-01-01

The brain is a self-organizing system which displays self-similarities at different spatial and temporal scales. Thus, the complexity of its dynamics, associated to efficient processing and functional advantages, is expected to be captured by a measure of its scale-free (fractal) properties. Under the hypothesis that the fractal dimension (FD) of the electroencephalographic signal (EEG) is optimally sensitive to the neuronal dysfunction secondary to a brain lesion, we tested the FD's ability in assessing two key processes in acute stroke: the clinical impairment and the recovery prognosis. Resting EEG was collected in 36 patients 4-10 days after a unilateral ischemic stroke in the middle cerebral artery territory and 19 healthy controls. National Health Institute Stroke Scale (NIHss) was collected at T0 and 6 months later. Highuchi FD, its inter-hemispheric asymmetry (FDasy) and spectral band powers were calculated for EEG signals. FD was smaller in patients than in controls (1.447±0.092 vs 1.525±0.105) and its reduction was paired to a worse acute clinical status. FD decrease was associated to alpha increase and beta decrease of oscillatory activity power. Larger FDasy in acute phase was paired to a worse clinical recovery at six months. FD in our patients captured the loss of complexity reflecting the global system dysfunction resulting from the structural damage. This decrease seems to reveal the intimate nature of structure-function unity, where the regional neural multi-scale self-similar activity is impaired by the anatomical lesion. This picture is coherent with neuronal activity complexity decrease paired to a reduced repertoire of functional abilities. FDasy result highlights the functional relevance of the balance between homologous brain structures' activities in stroke recovery.

An Optical Oxygen Sensor for Long-Term Continuous Monitoring of Dissolved Oxygen in Perfused Bioreactors

NASA Technical Reports Server (NTRS)

Gao, F. G.; Jeevarajan, A. S.; Anderson, M. M.

2002-01-01

For long-term growth of man1ITlalian cells in perfused bioreactors, it is essential to monitor the concentration of dissolved oxygen (DO) present in the culture medium to quantitate and control level of DO. Continuous measurement of the amount of DO in the cell culture medium in-line under sterile conditions in NASA's perfused bioreactor requires that the oxygen sensor provide increased sensitivity and be sterilizable and nontoxic. Additionally, long-term cell culture experiments require that the calibration be maintained several weeks or months. Although there are a number of sensors for dissolved oxygen on the market and under development elsewhere, very few meet these stringent conditions. An optical oxygen sensor (BOXY) based on dynamic fluorescent quenching and a pulsed blue LED light source was developed in our laboratory to address these requirements. Tris( 4,7 -diphenyl-l, 1 O-phenanthroline )ruthenium(II) chloride is employed as the fluorescent dye indicator. The sensing element consists of a glass capillary (OD 4.0 mm; ID 2.0 mm) coated internally with a thin layer of the fluorescent dye in silicone matrix and overlayed with a black shielding layer. Irradiation of the sensing element with blue light (blue LED with emission maximum at 475 nm) generates a red fluorescence centered at 626 nm. The fluorescence intensity is correlated to the concentration of DO present in the culture medium, following the modified non-linear Stern-Volmer equation. By using a pulsed irradiating light source, the problem of dye-bleaching, which is often encountered in long-term continuous measurements of tIns type, 'is minimized. To date we achieved sensor resolution of 0.3 mmHg at 50 mmHg p02, and 0.6 mmHg at 100 mmHg p02, with a response time of about one minute. Calibration was accomplished in sterile phosphate-buffered saline with a blood-gas analyzer (BGA) measurement as reference. Stand-alone software was also developed to control the sensor and bioreactor as well as to

In vivo aerobic metabolism of the rainbow trout gut and the effects of an acute temperature increase and stress event.

PubMed

Brijs, Jeroen; Gräns, Albin; Hjelmstedt, Per; Sandblom, Erik; van Nuland, Nicole; Berg, Charlotte; Axelsson, Michael

2018-05-24

The fish gut is responsible for numerous potentially energetically costly processes, yet, little is known about its metabolism. Here, we provide the first in vivo measurements for aerobic metabolism of the gut in a teleost fish by measuring gut blood flow, as well as arterial and portal venous oxygen content. At 10°C, gut oxygen uptake rates were 4.3±0.5 ml O 2 h -1 kg -1 (∼11% of whole animal oxygen uptake). Following acute warming to 15°C, gut blood flow increased ∼3.4-fold and gut oxygen uptake rate increased ∼3.7-fold (16.0±3.3 ml O 2 h -1 kg -1 ), now representing ∼25% of whole animal oxygen uptake. Although gut blood flow decreased following an acute stress event at 15°C, gut oxygen uptake remained unchanged due to a ∼2-fold increase in oxygen extraction. The high metabolic thermal sensitivity of the gut discovered here could have important implications on the overall aerobic capacity and performance of fish and warrants further investigations. © 2018. Published by The Company of Biologists Ltd.

Carboxyhemoglobin and methemoglobin levels as prognostic markers in acute pulmonary embolism.

PubMed

Kakavas, Sotirios; Papanikolaou, Aggeliki; Ballis, Evangelos; Tatsis, Nikolaos; Goga, Christina; Tatsis, Georgios

2015-04-01

Carboxyhemoglobin (COHb) and methemoglobin (MetHb) levels have been associated with a poor outcome in patients with various pathological conditions including cardiovascular diseases. Our aim was to retrospectively assess the prognostic value of arterial COHb and MetHb in patients with acute pulmonary embolism (PE). We conducted a retrospective study of 156 patients admitted in a pulmonary clinic due to acute PE. Measured variables during emergency department evaluation that were retrospectively analyzed included the ratio of the partial pressure of oxygen in arterial blood to the fraction of oxygen in inspired gas, Acute Physiology and Chronic Health Evaluation II score, risk stratification indices, and arterial blood gases. The association between arterial COHb and MetHb levels and disease severity or mortality was evaluated using bivariate tests and logistic regression analysis. Arterial COHb and MetHb levels correlated with Acute Physiology and Chronic Health Evaluation II and pulmonary severity index scores. Furthermore, arterial COHb and MetHb levels were associated with troponin T and N-terminal pro-B-type natriuretic peptide levels. In univariate logistic regression analysis, COHb and MetHb levels were both significantly associated with an increased risk of death. However, in multivariate analysis, only COHb remained significant as an independent predictor of in-hospital mortality. Our preliminary data suggest that arterial COHb and MetHb levels reflect the severity of acute PE, whereas COHb levels are independent predictors of in hospital death in patients in this clinical setting. These findings require further prospective validation. Copyright © 2015 Elsevier Inc. All rights reserved.

Bolus versus continuous low dose of enalaprilat in congestive heart failure with acute refractory decompensation.

PubMed

Podbregar, M; Voga, G; Horvat, M; Zuran, I; Krivec, B; Skale, R; Pareznik, R

1999-01-01

The first dose of angiotensin-converting enzyme (ACE) inhibitors may trigger a considerable fall of blood pressure in chronic heart failure. The response may be dose-related. To determine hemodynamic and systemic oxygenation effects of low-dose enalaprilat, we administered intravenous enalaprilat (0.004 mg/kg) as bolus (group B) or continuous 1-hour infusion (group C) in 20 patients with congestive heart failure due to ischemic heart disease with acute decompensation refractory to inotropic, vasodilator and diuretic therapy. Hemodynamic and systemic oxygenation variables were recorded at baseline (+0 min), +30, +60, +120, +180, and +360 min after the start of intervention. Mean arterial pressure (MAP) (p < 0. 001), mean pulmonary artery pressure (MPAP) (p < 0.001), pulmonary artery occlusion pressure (PAOP) (p < 0.001), oxygen extraction ratio (ER) (p < 0.026) decreased regardless of enalaprilat application. Compared to group B, there was in group C prolonged decrease of MAP, MPAP, PAOP, ER and increase of pulmonary artery oxyhemoglobin saturation in regard to baseline values. Cardiac index, heart rate, central venous pressure and oxygen consumption index did not change. A low dose of intravenous enalaprilat (0.004 mg/kg) can be used to safely improve hemodynamics and systemic oxygenation in congestive heart failure due to ischemic heart disease with acute refractory decompensation.

Cutaneous respirometry by dynamic measurement of mitochondrial oxygen tension for monitoring mitochondrial function in vivo.

PubMed

Harms, Floor A; Voorbeijtel, Wilhelmina J; Bodmer, Sander I A; Raat, Nicolaas J H; Mik, Egbert G

2013-09-01

Progress in diagnosis and treatment of mitochondrial dysfunction in chronic and acute disease could greatly benefit from techniques for monitoring of mitochondrial function in vivo. In this study we demonstrate the feasibility of in vivo respirometry in skin. Mitochondrial oxygen measurements by means of oxygen-dependent delayed fluorescence of protoporphyrin IX are shown to provide a robust basis for measurement of local oxygen disappearance rate (ODR). The fundamental principles behind the technology are described, together with an analysis method for retrievel of respirometry data. The feasibility and reproducibility of this clinically useful approach are demonstrated in a series of rats. Copyright © 2012 Elsevier B.V. All rights reserved.

Out-of-hospital opioid therapy of palliative care patients with "acute dyspnoea": a retrospective multicenter investigation.

PubMed

Wiese, Christoph H R; Barrels, Utz E; Graf, Bernhard M; Hanekop, Gerd G

2009-01-01

Prehospital emergency physicians (EP) are often confronted with the acute care of palliative care patients. Dyspnoea is a frequent acute symptom and its causes often differ from the generally known emergency medical causes. Till now, there have been no relevant concepts for emergency care of palliative care patients for their specific symptoms. Over a 24-month period, the authors retrospectively investigated all out-of-hospital emergency medical services for palliative care patients with acute dyspnoea at four emergency physician support points. The evaluation of these services was followed retrospectively on the basis of the therapy carried out by the EP (Group 1: therapy with morphine and oxygen; Group 2: therapy with morphine, bronchodilator effective drugs and oxygen; Group 3: therapy with bronchodilator effective drugs and oxygen; Group 4: therapy with oxygen; Group 5: no medical treatment). Moreover, EPs were interviewed about their actions and their uncertainties in the treatment of palliative care patients. The diagnosis of acute dyspnoea in palliative care patients occurred 121 times (116 patients were integrated in the present investigation) within the defined period. In total, 116 patients were included (Group 1: 21, Group 2: 29, Group 3: 31, Group 4: 28, and Group 5: 7). Dyspnoea was satisfactorily treated in 41 percent of the patients (Group 1: 67 percent, Group 2: 52 percent, Group 3: 22 percent, Group 4: 18 percent, and Group 5: 71 percent). Most EPs (70 percent) revealed uncertainties in emergency medical therapy for patients at the end of life. The current investigation showed a significant relief of acute dyspnoea when using opioids, in contrast with the established out-of-hospital emergency medical therapy for acute dyspnoea. Therefore, opioids should be recommended for emergency medical therapy of dyspnoea in palliative care patients. Clinical studies that recommend the use of effective opioids for the treatment of dyspnoea in palliative care

High Pressure Oxygen A-Band Spectra

NASA Astrophysics Data System (ADS)

Drouin, Brian; Sung, Keeyoon; Yu, Shanshan; Lunny, Elizabeth M.; Bui, Thinh Quoc; Okumura, Mitchio; Rupasinghe, Priyanka; Bray, Caitlin; Long, David A.; Hodges, Joseph; Robichaud, David; Benner, D. Chris; Devi, V. Malathy; Hoo, Jiajun

2015-06-01

Composition measurements from remote sensing platforms require knowledge of air mass to better than the desired precision of the composition. Oxygen spectra allow determination of air mass since the mixing ratio of oxygen is fixed. The OCO-2 mission is currently retrieving carbon dioxide concentration using the oxygen A-band for air mass normalization. The 0.25% accuracy desired for the carbon dioxide concentration has pushed the state-of-the-art for oxygen spectroscopy. To produce atmospheric pressure A-band cross-sections with this accuracy requires a sophisticated line-shape model (Galatry or Speed-Dependent) with line mixing (LM) and collision induced absorption (CIA). Models of each of these phenomena exist, but an integrated self-consistent model must be developed to ensure accuracy. This presentation will describe the ongoing effort to parameterize these phenomena on a representative data set created from complementary experimental techniques. The techniques include Fourier transform spectroscopy (FTS), photo-acoustic spectroscopy (PAS) and cavity ring-down spectroscopy (CRDS). CRDS data allow long-pathlength measurements with absolute intensities, providing lineshape information as well as LM and CIA, however the subtleties of the lineshape are diminished in the saturated line-centers. Conversely, the short paths and large dynamic range of the PAS data allow the full lineshape to be discerned, but with an arbitrary intensity axis. Finally, the FTS data provides intermediate paths and consistency across a broad pressure range. These spectra are all modeled with the Labfit software using first the spectral line database HITRAN, and then model values are adjusted and fitted for better agreement with the data.

Enhanced muscular oxygen extraction in athletes exaggerates hypoxemia during exercise in hypoxia.

PubMed

Van Thienen, Ruud; Hespel, Peter

2016-02-01

High rate of muscular oxygen utilization facilitates the development of hypoxemia during exercise at altitude. Because endurance training stimulates oxygen extraction capacity, we investigated whether endurance athletes are at higher risk to developing hypoxemia and thereby acute mountain sickness symptoms during exercise at simulated high altitude. Elite athletes (ATL; n = 8) and fit controls (CON; n = 7) cycled for 20 min at 100 W (EX100W), as well as performed an incremental maximal oxygen consumption test (EXMAX) in normobaric hypoxia (0.107 inspired O2 fraction) or normoxia (0.209 inspired O2 fraction). Cardiorespiratory responses, arterial Po2 (PaO2), and oxygenation status in m. vastus lateralis [tissue oxygenation index (TOIM)] and frontal cortex (TOIC) by near-infrared spectroscopy, were measured. Muscle O2 uptake rate was estimated from change in oxyhemoglobin concentration during a 10-min arterial occlusion in m. gastrocnemius. Maximal oxygen consumption in normoxia was 70 ± 2 ml·min(-1·)kg(-1) in ATL vs. 43 ± 2 ml·min(-1·)kg(-1) in CON, and in hypoxia decreased more in ATL (-41%) than in CON (-25%, P < 0.05). Both in normoxia at PaO2 of ∼95 Torr, and in hypoxia at PaO2 of ∼35 Torr, muscle O2 uptake was twofold higher in ATL than in CON (0.12 vs. 0.06 ml·min(-1)·100 g(-1); P < 0.05). During EX100W in hypoxia, PaO2 dropped to lower (P < 0.05) values in ATL (27.6 ± 0.7 Torr) than in CON (33.5 ± 1.0 Torr). During EXMAX, but not during EX100W, TOIM was ∼15% lower in ATL than in CON (P < 0.05). TOIC was similar between the groups at any time. This study shows that maintenance of high muscular oxygen extraction rate at very low circulating PaO2 stimulates the development of hypoxemia during submaximal exercise in hypoxia in endurance-trained individuals. This effect may predispose to premature development of acute mountain sickness symptoms during exercise at altitude. Copyright © 2016 the American Physiological Society.

Evolution of Force Sensing Technologies.

PubMed

Shah, Dipen

2017-06-01

In order to Improve the procedural success and long-term outcomes of catheter ablation techniques for atrial fibrillation (AF), an Important unfulfilled requirement is to create durable electrophysiologically complete lesions. Measurement of contact force (CF) between the catheter tip and the target tissue can guide physicians to optimise both mapping and ablation procedures. Contact force can affect lesion size and clinical outcomes following catheter ablation of AF. Force sensing technologies have matured since their advent several years ago, and now allow the direct measurement of CF between the catheter tip and the target myocardium in real time. In order to obtain complete durable lesions, catheter tip spatial stability and stable contact force are important. Suboptimal energy delivery, lesion density/contiguity and/or excessive wall thickness of the pulmonary vein-left atrial (PV-LA) junction may result in conduction recovery at these sites. Lesion assessment tools may help predict and localise electrical weak points resulting in conduction recovery during and after ablation. There is increasing clinical evidence to show that optimal use of CF sensing during ablation can reduce acute PV re-conduction, although prospective randomised studies are desirable to confirm long-term favourable clinical outcomes. In combination with optimised lesion assessment tools, contact force sensing technology has the potential to become the standard of care for all patients undergoing AF catheter ablation.

Effect of ambient oxygen on the photoluminescence of sol-gel-derived nanocrystalline ZrO2:Eu,Nb

NASA Astrophysics Data System (ADS)

Puust, Laurits; Kiisk, Valter; Eltermann, Marko; Mändar, Hugo; Saar, Rando; Lange, Sven; Sildos, Ilmo; Dolgov, Leonid; Matisen, Leonard; Jaaniso, Raivo

2017-06-01

The development of inorganic nanophosphors is an active research field due to many applications, including optical gas sensing materials. We found a systematic dependence of the photoluminescence (PL) of europium (Eu3+) impurity ions in zirconia (ZrO2) nanocrystals on the ambient oxygen concentration in a O2/N2 mixture at normal pressure. Europium-doped ZrO2 powders were synthesized via a sol-gel route. Heat-treatment at 1200 °C resulted in a well-developed monoclinic phase (XRD crystallite size of ~50 nm) and an intense PL of Eu3+ ions residing in the dominant phase (Eu3+ was excited directly at 395 or 464 nm). Co-doping with niobium resulted in a narrowing of the PL emission lines. Only Nb5+ was detected by XPS and is believed to charge-compensate Eu3+ activators throughout the material leading to a more regular crystal lattice. At room temperature, the exposure to oxygen suppressed the Eu3+ fluorescence, whereas, at elevated temperatures (300 °C), the effect was reversed. At 300 °C and under a focused continuous laser beam, a substantial PL response (>50%) was achieved when switching 100% of N2 for 100% of O2. PL decay kinetics clearly showed that at 300 °C fluorescence quenching centers were induced within the material by oxygen desorption. The relatively fast (<5 min) and sub-linear PL response to the changes of oxygen concentration shows that ZrO2:Eu,Nb is a promising PL-based oxygen sensing material over a wide-range of oxygen pressures.

Resveratrol induces acute endothelium-dependent renal vasodilation mediated through nitric oxide and reactive oxygen species scavenging

PubMed Central

Gordish, Kevin L.

2014-01-01

Resveratrol is suggested to have beneficial cardiovascular and renoprotective effects. Resveratrol increases endothelial nitric oxide synthase (eNOS) expression and nitric oxide (NO) synthesis. We hypothesized resveratrol acts as an acute renal vasodilator, mediated through increased NO production and scavenging of reactive oxygen species (ROS). In anesthetized rats, we found 5.0 mg/kg body weight (bw) of resveratrol increased renal blood flow (RBF) by 8% [from 6.98 ± 0.42 to 7.54 ± 0.17 ml·min−1·gram of kidney weight−1 (gkw); n = 8; P < 0.002] and decreased renal vascular resistance (RVR) by 18% from 15.00 ± 1.65 to 12.32 ± 1.20 arbitrary resistance units (ARU; P < 0.002). To test the participation of NO, we administered 5.0 mg/kg bw resveratrol before and after 10 mg/kg bw of the NOS inhibitor N-nitro-l-arginine methyl ester (l-NAME). l-NAME reduced the increase in RBF to resveratrol by 54% (from 0.59 ± 0.05 to 0.27 ± 0.06 ml·min−1·gkw−1; n = 10; P < 0.001). To test the participation of ROS, we gave 5.0 mg/kg bw resveratrol before and after 1 mg/kg bw tempol, a superoxide dismutase mimetic. Resveratrol increased RBF 7.6% (from 5.91 ± 0.32 to 6.36 ± 0.12 ml·min−1·gkw−1; n = 7; P < 0.001) and decreased RVR 19% (from 18.83 ± 1.37 to 15.27 ± 1.37 ARU). Tempol blocked resveratrol-induced increase in RBF (from 0.45 ± 0.12 to 0.10 ± 0.05 ml·min−1·gkw−1; n = 7; P < 0.03) and the decrease in RVR posttempol was 44% of the control response (3.56 ± 0.34 vs. 1.57 ± 0.21 ARU; n = 7; P < 0.006). We also tested the role of endothelium-derived prostanoids. Two days of 10 mg/kg bw indomethacin pretreatment did not alter basal blood pressure or RBF. Resveratrol-induced vasodilation remained unaffected. We conclude intravenous resveratrol acts as an acute renal vasodilator, partially mediated by increased NO production/NO bioavailability and superoxide scavenging but not by inducing vasodilatory cyclooxygenase products. PMID:24431202

Isolated Pt Atoms Stabilized by Amorphous Tungstenic Acid for Metal-Support Synergistic Oxygen Activation.

PubMed

Zhang, Qian; Qin, Xixi; Duanmu, Fanpeng; Ji, Huiming; Shen, Zhurui; Han, Xiaopeng; Hu, Wenbin

2018-06-05

Oxygen activation plays a crucial role in many important chemical reactions such as organics oxidation and oxygen reduction. For developing highly active materials for oxygen activation, herein, we report an atomically dispersed Pt on WO3 nanoplates stabilized by in-situ formed amorphous H2WO4 out-layer and the mechanism for activating molecular oxygen. Experimental and theoretical studies demonstrate that the isolated Pt atoms coordinated with oxygen atoms from [WO6] and water of H2WO4, consequently leading to optimized surface electronic configuration and strong metal support interaction (SMSI). In exemplified reactions of butanone oxidation sensing and oxygen reduction, the atomic Pt/WO3 hybrid exhibits superior activity than those of Pt nanoclusters/WO3 and bare WO3 as well as enhanced long-term durability. This work will provide insight on the origin of activity and stability for atomically dispersed materials, thus promoting the development of highly efficient and durable single atom-based catalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A mechanistic study of hydrogen gas sensing by PdO nanoflake thin films at temperatures below 250 °C.

PubMed

Chiang, Yu-Ju; Li, Kuang-Chung; Lin, Yi-Chieh; Pan, Fu-Ming

2015-02-07

We prepared PdO nanoflake thin films on the SiO2 substrate by reactive sputter deposition, and studied their sensing response to H2 at temperatures between 25 and 250 °C. In addition to the oxygen ionosorption model, which is used to describe the early H2 sensing response over the temperature range studied, the H2 sensing kinetics of the PdO thin films can be separated into three temperature regimes: temperatures below 100 °C, around 150 °C and above 200 °C. At temperatures below 100 °C, PdO reduction is the dominant reaction affecting the H2 sensing behavior. At temperatures around 150 °C, Pd reoxidation kinetically competes with PdO reduction leading to a complicated sensing characteristic. Active PdO reduction by H2 promotes the continuing growth of Pd nanoislands, facilitating dissociative oxygen adsorption and thus the subsequent Pd reoxidation in the H2-dry air gas mixture. The kinetic competition between the PdO reduction and reoxidation at 150 °C leads to the observation of an inverse of the increase in the sensor conductivity. At temperatures above 200 °C, the PdO sensor exhibits a sensor signal monotonically increasing with the H2 concentration, and the H2 sensing behavior is consistent with the Mars-van-Krevelen redox mechanism.

Maximal oxygen consumption increases with temperature in the European eel (Anguilla anguilla) through increased heart rate and arteriovenous extraction.

PubMed

Claësson, Débora; Wang, Tobias; Malte, Hans

2016-01-01

Global warming results in increasing water temperature, which may represent a threat to aquatic ectotherms. The rising temperature affects ecology through physiology, by exerting a direct limiting effect on the individual. The mechanism controlling individual thermal tolerance is still elusive, but some evidence shows that the heart plays a central role, and that insufficient transport of oxygen to the respiring tissues may determine the thermal tolerance of animals. In this study, the influence of the heart in thermal limitation was investigated by measurements of aerobic scope in the European eel ( Anguilla anguilla ) together with measurements of cardiac output during rest and activity. Aerobic capacity was not limited by an acutely increased temperature in the European eel. Oxygen demand was met by an increase in heart rate and arteriovenous extraction. These findings suggest that thermal tolerance during exposure to acute temperature changes is not defined by oxygen transport capacity in the eel, and other mechanisms may play a central role in limiting thermal tolerance in these fish.

Acute allograft failure in thoracic organ transplantation.

PubMed

Jahania, M S; Mullett, T W; Sanchez, J A; Narayan, P; Lasley, R D; Mentzer, R M

2000-01-01

Thoracic organ transplantation is an effective form of treatment for end-stage heart and lung disease. Despite major advances in the field, transplant patients remain at risk for acute allograft dysfunction, a major cause of early and late mortality. The most common causes of allograft failure include primary graft failure secondary to inadequate heart and lung preservation during cold storage, cellular rejection, and various donor-recipient-related factors. During cold storage and early reperfusion, heart and lung allografts are vulnerable to intracellular calcium overload, acidosis, cell swelling, injury mediated by reactive oxygen species, and the inflammatory response. Brain death itself is associated with a reduction in myocardial contractility, and recipient-related factors such as preexisting pulmonary hypertension can lead to acute right heart failure and the pulmonary reimplantation response. The development of new methods to prevent or treat these various causes of acute graft failure could lead to a marked improvement in short- and long-term survival of patients undergoing thoracic organ transplantation.