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Sample records for acute oxygen sensing

  1. Reactive Oxygen Species and Cellular Oxygen Sensing

    PubMed Central

    Cash, Timothy P; Pan, Yi; Simon, M. Celeste

    2008-01-01

    Many organisms activate adaptive transcriptional programs to help them cope with decreased oxygen levels, or hypoxia, in their environment. These responses are triggered by various oxygen sensing systems in bacteria, yeast and metazoans. In metazoans, the hypoxia inducible factors (HIFs) mediate the adaptive transcriptional response to hypoxia by upregulating genes involved in maintaining bioenergetic homeostasis. The HIFs in turn are regulated by HIF-specific prolyl hydroxlase activity, which is sensitive to cellular oxygen levels and other factors such as tricarboxylic acid cycle metabolites and reactive oxygen species (ROS). Establishing a role for ROS in cellular oxygen sensing has been challenging since ROS are intrinsically unstable and difficult to measure. However, recent advances in fluorescence energy transfer resonance (FRET)-based methods for measuring ROS are alleviating some of the previous difficulties associated with dyes and luminescent chemicals. In addition, new genetic models have demonstrated that functional mitochondrial electron transport and associated ROS production during hypoxia are required for HIF stabilization in mammalian cells. Current efforts are directed at how ROS mediate prolyl hydroxylase activity and hypoxic HIF stabilization. Progress in understanding this process has been enhanced by the development of the FRET-based ROS probe, an vivo prolyl hydroxylase reporter and various genetic models harboring mutations in components of the mitochondrial electron transport chain. PMID:17893032

  2. Acute use of oxygen therapy

    PubMed Central

    Pilcher, Janine; Beasley, Richard

    2015-01-01

    Summary A major change is needed in the entrenched culture of routinely administering high-concentration oxygen to acutely ill patients regardless of need. Oxygen is a drug that should be prescribed for specific indications. There should be a documented target range for oxygen saturation, and regular monitoring of the patient’s response. There are risks from unrelieved hypoxaemia due to insufficient oxygen therapy, and from provoked hyperoxaemia due to excessive oxygen therapy. Oxygen therapy should therefore be titrated so that the saturation is within a range that avoids these risks. If oxygen requirements are increasing, the clinician should review the patient and consider transfer to a higher level of care. If oxygen requirements are decreasing, consider reducing or discontinuing oxygen therapy. PMID:26648631

  3. Oxygen and carbon dioxide sensing

    NASA Technical Reports Server (NTRS)

    Ren, Fan (Inventor); Pearton, Stephen John (Inventor)

    2012-01-01

    A high electron mobility transistor (HEMT) capable of performing as a CO.sub.2 or O.sub.2 sensor is disclosed, hi one implementation, a polymer solar cell can be connected to the HEMT for use in an infrared detection system. In a second implementation, a selective recognition layer can be provided on a gate region of the HEMT. For carbon dioxide sensing, the selective recognition layer can be, in one example, PEI/starch. For oxygen sensing, the selective recognition layer can be, in one example, indium zinc oxide (IZO). In one application, the HEMTs can be used for the detection of carbon dioxide and oxygen in exhaled breath or blood.

  4. Oxygen Sensing Difluoroboron Dinaphthoylmethane Polylactide

    PubMed Central

    DeRosa, Christopher A.; Samonina-Kosicka, Jelena; Fan, Ziyi; Hendargo, Hansford C.; Weitzel, Douglas H.; Palmer, Gregory M.; Fraser, Cassandra L.

    2015-01-01

    Dual emissive luminescence properties of solid-state difluoroboron β-diketonate-poly(lactic acid) (BF2bdk-PLA) materials have been utilized as biological oxygen sensors. Dyes with red-shifted absorption and emission are important for multiplexing and in vivo imaging, thus hydroxyl-functionalized dinaphthoylmethane initiators and dye-PLA conjugates BF2dnm(X)PLA (X = H, Br, I) with extended conjugation were synthesized. The luminescent materials show red-shifted absorbance (~435 nm) and fluorescence tunability by molecular weight. Fluorescence colors range from yellow (~530 nm) in 10 – 12 kDa polymers to green (~490 nm) in 20 – 30 kDa polymers. Room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) are present under a nitrogen atmosphere. For the iodine-substituted derivative, BF2dnm(I)PLA, clearly distinguishable fluorescence (green) and phosphorescence (orange) peaks are present, making it ideal for ratiometric oxygen-sensing and imaging. Bromide and hydrogen analogues with weaker relative phosphorescence intensities and longer phosphorescence lifetimes can be used as highly sensitive, concentration independent, lifetime-based oxygen sensors or for gated emission detection. BF2dnm(I)PLA nanoparticles were taken up by T41 mouse mammary cells and successfully demonstrated differences in vitro ratiometric measurement of oxygen. PMID:26056421

  5. Oxygen sensing strategies in mammals and bacteria.

    PubMed

    Taabazuing, Cornelius Y; Hangasky, John A; Knapp, Michael J

    2014-04-01

    The ability to sense and adapt to changes in pO2 is crucial for basic metabolism in most organisms, leading to elaborate pathways for sensing hypoxia (low pO2). This review focuses on the mechanisms utilized by mammals and bacteria to sense hypoxia. While responses to acute hypoxia in mammalian tissues lead to altered vascular tension, the molecular mechanism of signal transduction is not well understood. In contrast, chronic hypoxia evokes cellular responses that lead to transcriptional changes mediated by the hypoxia inducible factor (HIF), which is directly controlled by post-translational hydroxylation of HIF by the non-heme Fe(II)/αKG-dependent enzymes FIH and PHD2. Research on PHD2 and FIH is focused on developing inhibitors and understanding the links between HIF binding and the O2 reaction in these enzymes. Sulfur speciation is a putative mechanism for acute O2-sensing, with special focus on the role of H2S. This sulfur-centered model is discussed, as are some of the directions for further refinement of this model. In contrast to mammals, bacterial O2-sensing relies on protein cofactors that either bind O2 or oxidatively decompose. The sensing modality for bacterial O2-sensors is either via altered DNA binding affinity of the sensory protein, or else due to the actions of a two-component signaling cascade. Emerging data suggests that proteins containing a hemerythrin-domain, such as FBXL5, may serve to connect iron sensing to O2-sensing in both bacteria and humans. As specific molecular machinery becomes identified, these hypoxia sensing pathways present therapeutic targets for diseases including ischemia, cancer, or bacterial infection. PMID:24468676

  6. Oxygen Sensing Strategies in Mammals and Bacteria

    PubMed Central

    Taabazuing, Cornelius Y.; Hangasky, John A.; Knapp, Michael J.

    2014-01-01

    The ability to sense and adapt to changes in pO2 is crucial for basic metabolism in most organisms, leading to elaborate pathways for sensing hypoxia (low pO2). This review focuses on the mechanisms utilized by mammals and bacteria to sense hypoxia. While responses to acute hypoxia in mammalian tissues lead to altered vascular tension, the molecular mechanism of signal transduction is not well understood. In contrast, chronic hypoxia evokes cellular responses that lead to transcriptional changes mediated by the hypoxia inducible factor (HIF), which is directly controlled by post-translational hydroxylation of HIF by the non-heme Fe(II)/αKG-dependent enzymes FIH and PHD2. Research on PHD2 and FIH is focused on developing inhibitors and understanding the links between HIF binding and the O2 reaction in these enzymes. Sulfur speciation is a putative mechanism for acute O2-sensing, with special focus on the role of H2S. This sulfur-centered model is discussed, as are some of the directions for further refinement of this model. In contrast to mammals, bacterial O2-sensing relies on protein cofactors that either bind O2 or oxidatively decompose. The sensing modality for bacterial O2-sensors is either via altered DNA binding affinity of the sensory protein, or else due to the actions of a two-component signaling cascade. Emerging data suggests that proteins containing a hemerythrin-domain, such as FBXL5, may serve to connect iron sensing to O2-sensing in both bacteria and humans. As specific molecular machinery becomes identified, these hypoxia sensing pathways present therapeutic targets for diseases including ischemia, cancer, or bacterial infection. PMID:24468676

  7. Oxygen derived variables in acute respiratory failure.

    PubMed

    Covelli, H D; Nessan, V J; Tuttle, W K

    1983-08-01

    The clinical course of 33 patients with acute respiratory distress syndrome (ARDS) was monitored by noninvasive oxygen derived variables and compared to data obtained by invasive monitoring. A total of 350 data points were used to compare the physiologic shunt fraction (Qsp/Qt) with the ratio of arterial oxygen to inspired oxygen concentration (PaO2/FIO2), the alveolar-arterial oxygen pressure difference [P(A-a)O2], the respiratory index (RI)-[P(A-a)O2/PaO2], and the ratio of arterial oxygen to alveolar oxygen (a/A). The PaO2/FIO2 ratio, the RI and the aA ratio correlated well with Qsp/Qt (r = 0.87 to 0.94). The P(A-a)O2 correlated less well (r = 0.68). Changes in the cardiac index (CI) and the arteriovenous oxygen content difference C(a-v)O2 had only a minimal effect on the correlation of the oxygen derived variables with Qsp/Qt, although a higher correlation resulted when these extrapulmonary factors were within normal range. We conclude that a number of oxygen derived variables may accurately reflect the degree of Qsp/Qt. The PaO2/FIO2 ratio is the easiest of these variables to calculate, yet accurately predicts the degree of Qsp/Qt throughout a course of acute respiratory failure. PMID:6409506

  8. A miniature inexpensive, oxygen sensing element

    SciTech Connect

    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 that 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.

  9. Evolution and physiology of neural oxygen sensing.

    PubMed

    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

  10. 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

  11. Biosupercapacitors for powering oxygen sensing devices.

    PubMed

    Kizling, Michal; Draminska, Sylwia; Stolarczyk, Krzysztof; Tammela, Petter; Wang, Zhaohui; Nyholm, Leif; Bilewicz, Renata

    2015-12-01

    A biofuel cell comprising electrodes based on supercapacitive materials - carbon nanotubes and nanocellulose/polypyrrole composite was utilized to power an oxygen biosensor. Laccase Trametes versicolor, immobilized on naphthylated multi walled carbon nanotubes, and fructose dehydrogenase, adsorbed on a porous polypyrrole matrix, were used as the cathode and anode bioelectrocatalysts, respectively. The nanomaterials employed as the supports for the enzymes increased the surface area of the electrodes and provide direct contact with the active sites of the enzymes. The anode modified with the conducting polymer layer exhibited significant pseudocapacitive properties providing superior performance also in the high energy mode, e.g., when switching on/off the powered device. Three air-fructose biofuel cells connected in a series converted chemical energy into electrical giving 2 mW power and open circuit potential of 2V. The biofuel cell system was tested under various externally applied resistances and used as a powering unit for a laboratory designed two-electrode minipotentiostat and a laccase based sensor for oxygen sensing. Best results in terms of long time measurement of oxygen levels were obtained in the pulse mode -45 s for measurement and 15 min for self-recharging of the powering unit. PMID:25960258

  12. Oxygen-sensing under the influence of nitric oxide.

    PubMed

    Berchner-Pfannschmidt, Utta; Tug, Suzan; Kirsch, Michael; Fandrey, Joachim

    2010-03-01

    The transcription factor complex Hypoxia inducible factor 1 (HIF-1) controls the expression of most genes involved in adaptation to hypoxic conditions. Oxygen-dependency is maintained by prolyl- and asparagyl-4-hydroxylases (PHDs/FIH-1) belonging to the superfamily of iron(II) and 2-oxoglutarate dependent dioxygenases. Hydroxylation of the HIF-1alpha subunit by PHDs and FIH-1 leads to its degradation and inactivation. By hydroxylating HIF-1alpha in an oxygen-dependent manner PHDs and FIH-1 function as oxygen-sensing enzymes of HIF signalling. Besides molecular oxygen nitric oxide (NO), a mediator of the inflammatory response, can regulate HIF-1alpha accumulation, HIF-1 activity and HIF-1 dependent target gene expression. Recent studies addressing regulation of HIF-1 by NO revealed a complex and paradoxical picture. Acute exposure of cells to high doses of NO increased HIF-1alpha levels irrespective of the residing oxygen concentration whereas prolonged exposure to NO or low doses of this radical reduced HIF-1alpha accumulation even under hypoxic conditions. Several mechanisms were found to contribute to this paradoxical role of NO in regulating HIF-1. More recent studies support the view that NO regulates HIF-1 by modulating the activity of the oxygen-sensor enzymes PHDs and FIH-1. NO dependent HIF-1alpha accumulation under normoxia was due to direct inhibition of PHDs and FIH-1 most likely by competitive binding of NO to the ferrous iron in the catalytically active center of the enzymes. In contrast, reduced HIF-1alpha accumulation by NO under hypoxia was mainly due to enhanced HIF-1alpha degradation by induction of PHD activity. Three major mechanisms are discussed to be involved in enhancing the PHD activity despite the lack of oxygen: (1) NO mediated induction of a HIF-1 dependent feedback loop leading to newly expressed PHD2 and enhanced nuclear localization, (2) O2-redistribution towards PHDs after inhibition of mitochondrial respiration by NO, (3

  13. Ratiometric oxygen sensing using lanthanide luminescent emitting interfaces.

    PubMed

    Lehr, Joshua; Tropiano, Manuel; Beer, Paul D; Faulkner, Stephen; Davis, Jason J

    2015-11-14

    Herein we describe the first example of a ratiometric lanthanide luminescent oxygen sensing interface. Immobilisation of terbium and europium cyclen complexes on glass substrates was achieved by a novel aryl nitrene photografting approach. The resulting interfaces demonstrated a ratiometric oxygen response between 0 and 0.2 atm partial oxygen pressure. PMID:26376829

  14. Enhanced optical oxygen sensing using a newly synthesized ruthenium complex together with oxygen carriers.

    PubMed

    Ertekin, Kadriye; Kocak, Suleyman; Sabih Ozer, M; Aycan, Sule; Cetinkaya, Bekir

    2003-11-12

    In this article, an emission based, simple and fast method is proposed for the determination of gaseous oxygen. A newly synthesized fluorophore, dichloro-{2,6-bis[1-(4-dimethylamino-phenylimino) ethyl]pyridine}ruthenium(II) has been used for oxygen sensing together with oxygen carrier perfluorochemicals (PFCs) in silicon matrix. It should be noted that the solubility of oxygen in fluorocarbons is about three to ten times large as that observed in the parent hydrocarbons or in water, respectively. Employed PFCs are chemically and biochemically inert, have high dissolution capacities for oxygen, and, once doped into sensing film, considerably enhance the response of sensing agent. PMID:18969220

  15. Nano-Enriched and Autonomous Sensing Framework for Dissolved Oxygen.

    PubMed

    Shehata, Nader; Azab, Mohammed; Kandas, Ishac; Meehan, Kathleen

    2015-01-01

    This paper investigates a nano-enhanced wireless sensing framework for dissolved oxygen (DO). The system integrates a nanosensor that employs cerium oxide (ceria) nanoparticles to monitor the concentration of DO in aqueous media via optical fluorescence quenching. We propose a comprehensive sensing framework with the nanosensor equipped with a digital interface where the sensor output is digitized and dispatched wirelessly to a trustworthy data collection and analysis framework for consolidation and information extraction. The proposed system collects and processes the sensor readings to provide clear indications about the current or the anticipated dissolved oxygen levels in the aqueous media. PMID:26287211

  16. Correlative NAD(P)H-FLIM and oxygen sensing-PLIM for metabolic mapping.

    PubMed

    Kalinina, Sviatlana; Breymayer, Jasmin; Schäfer, Patrick; Calzia, Enrico; Shcheslavskiy, Vladislav; Becker, Wolfgang; Rück, Angelika

    2016-08-01

    Cellular responses to oxygen tension have been studied extensively. Oxygen tension can be determined by considering the phosphorescence lifetime of a phosphorescence sensor. The simultaneous usage of FLIM of coenzymes as NAD(P)H and FAD(+) and PLIM of oxygen sensors could provide information about correlation of metabolic pathways and oxygen tension. We investigated correlative NAD(P)H-FLIM and oxygen sensing-PLIM for simultaneously analyzing cell metabolism and oxygen tension. Cell metabolism and pO2 were observed under different hypoxic conditions in squamous carcinoma cell cultures and in complex ex vivo systems. Increased hypoxia induced an increase of the phosphorescence lifetime of Ru(BPY)3 and in most cases a decrease in the lifetime of NAD(P)H which is in agreement to the expected decrease of the protein-bound NAD(P)H during hypoxia. Oxygen was modulated directly in the mitochondrial membrane. Blocking of complex III and accumulation of oxygen could be observed by both the decrease of the phosphorescence lifetime of Ru(BPY)3 and a reduction of the lifetime of NAD(P)H which was a clear indication of acute changes in the redox state of the cells. For the first time simultaneous FLIM/PLIM has been shown to be able to visualize intracellular oxygen tension together with a change from oxidative to glycolytic phenotype. PMID:26990032

  17. Imaging Oxygen Metabolism In Acute Stroke Using MRI

    PubMed Central

    An, Hongyu; Ford, Andria L.; Vo, Katie D.; Liu, Qingwei; Chen, Yasheng; Lee, Jin-Moo; Lin, Weili

    2014-01-01

    The ability to image the ischemic penumbra during hyper-acute stroke promises to identify patients who may benefit from treatment intervention beyond population-defined therapeutic time windows. MR blood oxygenation level dependent (BOLD) contrast imaging has been explored in ischemic stroke. This review provides an overview of several BOLD-based methods, including susceptibility weighted imaging (SWI), R2, R2*, R2′, R2* under oxygen challenge, MR_OEF and MROMI approaches to assess cerebral oxygen metabolism in ischemic stroke. We will review the underlying pathophysiological basis of the imaging approaches, followed by a brief introduction of BOLD contrast. Finally, we will discuss the applications of the BOLD approaches in patients with ischemic stroke. BOLD-based methods hold promise for imaging tissue oxygenation during acute ischemia. Further technical refinement and validation studies in stroke patients against positron emission tomography (PET) measurements are needed. PMID:24707451

  18. Quality assessment of packaged foods by optical oxygen sensing

    NASA Astrophysics Data System (ADS)

    Papkovsky, Dmitri B.; O'Mahony, Fiach C.; Kerry, Joe P.; Ogurtsov, Vladimir I.

    2005-11-01

    A phase-fluorometric oxygen sensor system has been developed, which allows non-destructive measurement of residual oxygen levels in sealed containers such as packaged foods. It operates with disposable solid-state sensors incorporated in each pack, and a portable detector which interrogates with the sensors through a (semi)transparent packaging material. The system has been optimized for packaging applications and validated in small and medium scale trials with different types of food, including MAP hams, cheese, convenience foods, smoked fish, bakery. It has demonstrated high efficiency in monitoring package integrity, oxygen profiles in packs, performance of packaging process and many other research and quality control tasks, allowing control of 100% of packs. The low-cost batch-calibrated sensors have demonstrated reliability, safety, stability including direct contact with food, high efficiency in the low oxygen range. Another system, which also employs the fluorescence-based oxygen sensing approach, provides rapid assessment of microbial contamination (total viable counts) in complex samples such as food homogenates, industrial waste, environmental samples, etc. It uses soluble oxygen-sensitive probes, standard microtitter plates and fluorescence measurements on conventional plate reader to monitor growth of aerobic bacteria in small test samples (e.g. food homogenates) via their oxygen respiration. The assay provides high sample through put, miniaturization, speed, and can serve as alternative to the established methods such as agar plate colony counts and turbidimetry.

  19. [Normobaric oxygen therapy in acute medical care: myths versus reality].

    PubMed

    von Düring, Stephan; Bruchez, Stéphanie; Suppan, Laurent; Niquille, Marc

    2015-08-12

    Oxygen adiministration for both medical and traumatic emergencies is regarded as an essential component of resuscitation. However, many recent studies suggest that the use of oxygen should be more restrictive. Detrimental effects of normobaric oxygen therapy in patients suffering from hypercapnic respiratory diseases have been demonstrated, especially because of the suppression of the hypoxic drive. Apart from this particular situation, correction of hypoxemia is still a widely accepted treatment target, although there is growing evidence that hyperoxemia could be harmful in acute coronary syndromes and cardio-respiratory arrests. In other pathologies, such as stroke or hemorragic shock, the situation is still unclear, and further studies are needed to clarify the situation. Generally speaking, oxygen therapy should from now on be goal-directed, and early monitoring of both pulse oximetry and arterial blood gases is advised. PMID:26449100

  20. Oxygen therapy in acute exacerbations of chronic obstructive pulmonary disease

    PubMed Central

    Brill, Simon E; Wedzicha, Jadwiga A

    2014-01-01

    Acute exacerbations of chronic obstructive pulmonary disease (COPD) are important events in the history of this debilitating lung condition. Associated health care utilization and morbidity are high, and many patients require supplemental oxygen or ventilatory support. The last 2 decades have seen a substantial increase in our understanding of the best way to manage the respiratory failure suffered by many patients during this high-risk period. This review article examines the evidence underlying supplemental oxygen therapy during exacerbations of COPD. We first discuss the epidemiology and pathophysiology of respiratory failure in COPD during exacerbations. The rationale and evidence underlying oxygen therapy, including the risks when administered inappropriately, are then discussed, along with further strategies for ventilatory support. We also review current recommendations for best practice, including methods for improving oxygen provision in the future. PMID:25404854

  1. Acute pulmonary edema secondary to hyperbaric oxygen therapy.

    PubMed

    Obiagwu, Chukwudi; Paul, Vishesh; Chadha, Sameer; Hollander, Gerald; Shani, Jacob

    2015-02-01

    Hyperbaric oxygen therapy (HBOT) has been shown to be effective in the treatment of diabetic ulcers, air embolism, carbon monoxide poisoning and gas gangrene with minimal adverse effects. Very few cases of HBOT causing acute pulmonary edema (PE) has been described; with a study on dogs suggesting that a complication of this therapy could be PE. We describe the case of an 80-year-old man with a history of stable systolic heart failure and diabetes mellitus presenting with acute PE following treatment with HBOT for diabetic foot. PMID:25988073

  2. Acute pulmonary edema secondary to hyperbaric oxygen therapy

    PubMed Central

    Obiagwu, Chukwudi; Paul, Vishesh; Chadha, Sameer; Hollander, Gerald; Shani, Jacob

    2015-01-01

    Hyperbaric oxygen therapy (HBOT) has been shown to be effective in the treatment of diabetic ulcers, air embolism, carbon monoxide poisoning and gas gangrene with minimal adverse effects. Very few cases of HBOT causing acute pulmonary edema (PE) has been described; with a study on dogs suggesting that a complication of this therapy could be PE. We describe the case of an 80-year-old man with a history of stable systolic heart failure and diabetes mellitus presenting with acute PE following treatment with HBOT for diabetic foot. PMID:25988073

  3. On a magnetic-luminescent nanocomposite for oxygen sensing application: Construction, characterization and sensing performance.

    PubMed

    Chen, Tieyu; Dai, Henry; Peng, Xing

    2015-11-01

    This paper was devoted to the construction of a magnetic-luminescence nanocomposite for oxygen sensing application, where superparamagnetic Fe3O4 and silica molecular sieve MCM-41 were chosen as the inner core and the outer shell, respectively. A Ru(II) complex was grafted into MCM-41 shell through a coupling ligand N1-(5H-cyclopenta[1,2-b:5,4-b']dipyridin-5-ylidene)benzene-1,4-diamine (denoted as Dafo-Ph-NH2). The final composite was analyzed by electron microscope images, XRD, IR spectra, thermogravimetry and N2 adsorption/desorption. Oxygen sensing performance of this composite was evaluated. Sensitivity of 5.8 (the ratio of emission intensity in pure N2 to that in pure O2) and response time of 16s were obtained with good photostability. PMID:26099825

  4. 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

  5. Acute oxygen therapy: a review of prescribing and delivery practices.

    PubMed

    Cousins, Joyce L; Wark, Peter A B; 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

  6. Oxygen-sensing by arterial chemoreceptors: Mechanisms and medical translation.

    PubMed

    López-Barneo, José; Ortega-Sáenz, Patricia; González-Rodríguez, Patricia; Fernández-Agüera, M Carmen; Macías, David; Pardal, Ricardo; Gao, Lin

    2016-01-01

    Acute O2 sensing is necessary for the activation of cardiorespiratory reflexes (hyperventilation and sympathetic activation), which permit the survival of individuals under hypoxic environments (e.g. high altitude) or medical conditions presenting with reduced capacity for gas exchange between the lung alveoli and the blood. Changes in blood O2 tension are detected by the arterial chemoreceptors, in particular the carotid body (CB), which act in concert with the adrenal medulla (AM) to facilitate rapid adaptations to hypoxia. The field of arterial chemoreception has undergone a considerable expansion in recent years, with many of the fundamental observations made at the molecular and cellular levels serving to improve our understanding of the pathogenesis of numerous medical disorders, and even to propose advances in the treatment strategies. In this review, after a short historical preface, we describe the current model of chemosensory transduction based on the modulation of membrane K(+) channels by O2 in specialized chemoreceptor cells. Recent progress in elucidating the molecular mechanisms underlying the modulation of ion channels by O2 tension, which involves mitochondrial complex I, is also discussed. The discovery in the last few years of a specific population of neural crest-derived stem cells in the CB explains the reversible growth of this organ, an intriguing and unusual property of this type of neuronal tissue that contributes to acclimatization under chronic hypoxia. The essential homeostatic role of the CB-AM axis is clearly evident in newly generated mouse models that reach adulthood, albeit with CB and AM atrophy. These animals exhibit a marked intolerance to even mild hypoxia. CB inhibition or over-activation can have important medical consequences. Respiratory depression by general anesthetics or by opioid use is a common clinical condition that frequently causes death in susceptible individuals. An exaggerated sympathetic outflow due to over

  7. Reactive oxygen species in eradicating acute myeloid leukemic stem cells

    PubMed Central

    Zhang, Hui; Fang, Hai

    2014-01-01

    Leukemic stem cells (LSCs) have been proven to drive leukemia initiation, progression and relapse, and are increasingly being used as a critical target for therapeutic intervention. As an essential feature in LSCs, reactive oxygen species (ROS) homeostasis has been extensively exploited in the past decade for targeting LSCs in acute myeloid leukemia (AML). Most, if not all, agents that show therapeutic benefits are able to alter redox status by inducing ROS, which confers selectivity in eradicating AML stem cells but sparing normal counterparts. In this review, we provide the comprehensive update of ROS-generating agents in the context of their impacts on our understanding of the pathogenesis of AML and its therapy. We anticipate that further characterizing these ROS agents will help us combat against AML in the coming era of LSC-targeting strategy.

  8. Oxygen Sensing Neurons and Neuropeptides Regulate Survival after Anoxia in Developing C. elegans

    PubMed Central

    Flibotte, John J.; Jablonski, Angela M.; Kalb, Robert G.

    2014-01-01

    Hypoxic brain injury remains a major source of neurodevelopmental impairment for both term and preterm infants. The perinatal period is a time of rapid transition in oxygen environments and developmental resetting of oxygen sensing. The relationship between neural oxygen sensing ability and hypoxic injury has not been studied. The oxygen sensing circuitry in the model organism C. elegans is well understood. We leveraged this information to investigate the effects of impairments in oxygen sensing on survival after anoxia. There was a significant survival advantage in developing worms specifically unable to sense oxygen shifts below their preferred physiologic range via genetic ablation of BAG neurons, which appear important for conferring sensitivity to anoxia. Oxygen sensing that is mediated through guanylate cyclases (gcy-31, 33, 35) is unlikely to be involved in conferring this sensitivity. Additionally, animals unable to process or elaborate neuropeptides displayed a survival advantage after anoxia. Based on these data, we hypothesized that elaboration of neuropeptides by BAG neurons sensitized animals to anoxia, but further experiments indicate that this is unlikely to be true. Instead, it seems that neuropeptides and signaling from oxygen sensing neurons operate through independent mechanisms, each conferring sensitivity to anoxia in wild type animals. PMID:24967811

  9. Oxygen sensing by the carotid body: mechanisms and role in adaptation to hypoxia.

    PubMed

    López-Barneo, José; González-Rodríguez, Patricia; Gao, Lin; Fernández-Agüera, M Carmen; Pardal, Ricardo; Ortega-Sáenz, Patricia

    2016-04-15

    Oxygen (O2) is fundamental for cell and whole-body homeostasis. Our understanding of the adaptive processes that take place in response to a lack of O2(hypoxia) has progressed significantly in recent years. The carotid body (CB) is the main arterial chemoreceptor that mediates the acute cardiorespiratory reflexes (hyperventilation and sympathetic activation) triggered by hypoxia. The CB is composed of clusters of cells (glomeruli) in close contact with blood vessels and nerve fibers. Glomus cells, the O2-sensitive elements in the CB, are neuron-like cells that contain O2-sensitive K(+)channels, which are inhibited by hypoxia. This leads to cell depolarization, Ca(2+)entry, and the release of transmitters to activate sensory fibers terminating at the respiratory center. The mechanism whereby O2modulates K(+)channels has remained elusive, although several appealing hypotheses have been postulated. Recent data suggest that mitochondria complex I signaling to membrane K(+)channels plays a fundamental role in acute O2sensing. CB activation during exposure to low Po2is also necessary for acclimatization to chronic hypoxia. CB growth during sustained hypoxia depends on the activation of a resident population of stem cells, which are also activated by transmitters released from the O2-sensitive glomus cells. These advances should foster further studies on the role of CB dysfunction in the pathogenesis of highly prevalent human diseases. PMID:26764048

  10. Oxygen Sensing by Arterial Chemoreceptors Depends on Mitochondrial Complex I Signaling.

    PubMed

    Fernández-Agüera, M Carmen; Gao, Lin; González-Rodríguez, Patricia; Pintado, C Oscar; Arias-Mayenco, Ignacio; García-Flores, Paula; García-Pergañeda, Antonio; Pascual, Alberto; Ortega-Sáenz, Patricia; López-Barneo, José

    2015-11-01

    O2 sensing is essential for mammalian homeostasis. Peripheral chemoreceptors such as the carotid body (CB) contain cells with O2-sensitive K(+) channels, which are inhibited by hypoxia to trigger fast adaptive cardiorespiratory reflexes. How variations of O2 tension (PO2) are detected and the mechanisms whereby these changes are conveyed to membrane ion channels have remained elusive. We have studied acute O2 sensing in conditional knockout mice lacking mitochondrial complex I (MCI) genes. We inactivated Ndufs2, which encodes a protein that participates in ubiquinone binding. Ndufs2-null mice lose the hyperventilatory response to hypoxia, although they respond to hypercapnia. Ndufs2-deficient CB cells have normal functions and ATP content but are insensitive to changes in PO2. Our data suggest that chemoreceptor cells have a specialized succinate-dependent metabolism that induces an MCI state during hypoxia, characterized by the production of reactive oxygen species and accumulation of reduced pyridine nucleotides, which signal neighboring K(+) channels. PMID:26437605

  11. 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

  12. 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.

  13. Hyperbaric Oxygen Therapy in Acute Ischemic Stroke: A Review

    PubMed Central

    Ding, Zheng; Tong, Wesley C.; Lu, Xiao-Xin; Peng, Hui-Ping

    2014-01-01

    Stroke, also known as cerebrovascular disease, is a common and serious neurological disease, which is also the fourth leading cause of death in the United States so far. Hyperbaric medicine, as an emerging interdisciplinary subject, has been applied in the treatment of cerebral vascular diseases since the 1960s. Now it is widely used to treat a variety of clinical disorders, especially hypoxia-induced disorders. However, owing to the complex mechanisms of hyperbaric oxygen (HBO) treatment, the therapeutic time window and the undefined dose as well as some common clinical side effects (such as middle ear barotrauma), the widespread promotion and application of HBO was hindered, slowing down the hyperbaric medicine development. In August 2013, the US Food and Drug Administration declared artery occlusion as one of the 13 specific indications for HBO therapy. This provides opportunities, to some extent, for the further development of hyperbaric medicine. Currently, the mechanisms of HBO therapy for ischemic stroke are still not very clear. This review focuses on the potential mechanisms of HBO therapy in acute ischemic stroke as well as the time window. PMID:25337089

  14. A plastic optical fiber sensor for the dual sensing of temperature and oxygen

    NASA Astrophysics Data System (ADS)

    Lo, Yu-Lung; Chu, Chen-Shane

    2008-04-01

    This study presents a low-cost plastic optical fiber sensor for the dual sensing of temperature and oxygen. The sensor features a commercially available epoxy glue coated on the side-polished fiber surface for temperature sensing and a fluorinated xerogel doped with platinum tetrakis pentrafluoropheny porphine (PtTFPP) coated on the fiber end for oxygen sensing. The temperature and oxygen indicators are both excited using a UV LED light source with a wavelength of 380 nm. The luminescence emission spectra of the two indicators are well resolved and exhibit no cross-talk effects. Overall, the results indicate that the dual sensor presented in this study provides an ideal solution for the non-contact, simultaneous sensing of temperature and oxygen in general biological and medical applications.

  15. Modulation of Perfusion and Oxygenation by Red Blood Cell Oxygen Affinity during Acute Anemia

    PubMed Central

    Cabrales, Pedro; Tsai, Amy G.; Intaglietta, Marcos

    2008-01-01

    Responses to exchange transfusion using red blood cells (RBCs) with modified hemoglobin (Hb) oxygen (O2) affinity were studied in the hamster window chamber model during acute anemia to determine its role on microvascular perfusion and tissue oxygenation. Allosteric effectors were introduced in the RBCs by electroporation. Inositol hexaphosphate (IHP) and 5-hydroxymethyl-2-furfural (5HMF) were used to decrease and increase Hb-O2 affinity. In vitro P50s (partial pressure of O2 at 50% Hb saturation) were modified to 10, 25, 45, and 50 mm Hg (normal P50 is 32 mm Hg). Allosteric effectors also decreased the Hill coefficient. Anemic condition was induced by isovolemic hemodilution exchanges using 6% dextran 70 kD to 18% hematocrit (Hct). Modified RBCs (at 18% Hct in 5% albumin solution) were infused by exchange transfusion of 35% of blood volume. Systemic parameters, microvascular perfusion, capillary perfusion (functional capillary density, FCD), and microvascular Po2 levels were measured. RBcs with P50 of 45 mm Hg increased tissue Po2 and decreased O2 delivery (Do2) and extraction (Vo2) and RBCs with P50 of 60 mmHg reduced FCD, microvascular flow, tissue Po2, Do2 and Vo2. Erythrocytes with increased Hb-O2 affinity maintained hemodynamic conditions, Do2 and decreased tissue Po2. This study shows that in an anemic condition, maximal tissue Po2 does not correspond to maximal Do2 and Vo2. PMID:17884988

  16. 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

  17. 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

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

    NASA Astrophysics Data System (ADS)

    Yang, Xiaozhou; Li, Yanxiao

    2016-01-01

    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.

  19. 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. PMID:26478986

  20. A Pyrene@Micelle Sensor for Fluorescent Oxygen Sensing

    PubMed Central

    Yuan, Yan-xia; Peng, Hong-shang; Ping, Jian-tao; Wang, Xiao-hui; You, Fang-tian

    2015-01-01

    For most fluorescent oxygen sensors developed today, their fabrication process is either time-consuming or needs specialized knowledge. In this work, a robust fluorescent oxygen sensor is facilely constructed by dissolving pyrene molecules into CTAB aqueous solution. The as-prepared pyrene@micelle sensors have submicron-sized diameter, and the concentration of utilized pyrene can be reduced as low as 0.8 mM but still can exhibit dominant excimer emission. The excimer fluorescence is sensitive to dissolved oxygen in both intensity and lifetime, and the respective Stern-Volmer plot follows a nonlinear behavior justified by a two-site model. Because of the merits of large Stokes shift (~140 nm), easy fabrication, and robustness, the pyrene@micelle sensors are very attractive for practical determination of oxygen. PMID:26539471

  1. 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

  2. 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. PMID:26113255

  3. Mechanisms of sensing and adaptive responses to low oxygen conditions in mammals and yeasts.

    PubMed

    Trendeleva, T A; Aliverdieva, D A; Zvyagilskaya, R A

    2014-08-01

    Oxygen is required for effective production of ATP and plays a key role in the maintenance of life for all organisms, excepting strict anaerobes. The ability of aerobic organisms to sense and respond to changes in oxygen level is a basic requirement for their survival. Eukaryotes have developed adaptive mechanisms to sense and respond to decreased oxygen concentrations (hypoxia) through adjustment of oxygen homeostasis by upregulating hypoxic and downregulating aerobic nuclear genes. This review summarizes recent data on mechanisms of cells sensing and responding to changes in oxygen availability in mammals and in yeasts. In the first part of the review, prominence is given to functional regulation and stabilization of hypoxia-inducible factors (HIFs), HIF-mediated regulation of electron transport flux and repression of lipogenesis, as well as to hypoxia-induced mitochondrial permeability transition (pore) opening, cell death, and autophagy. In the second part of the review emphasis is placed on oxygen sensing in nonpathogenic yeasts by heme, unsaturated fatty acids, and sterols, as well as on responses to hypoxia in fungal pathogens. PMID:25365485

  4. The role of high flow oxygen therapy in acute respiratory failure.

    PubMed

    Masclans, J R; Pérez-Terán, P; Roca, O

    2015-11-01

    Acute respiratory failure represents one of the most common causes of intensive care unit admission and oxygen therapy remains the first-line therapy in the management of these patients. In recent years, high-flow oxygen via nasal cannula has been described as a useful alternative to conventional oxygen therapy in patients with acute respiratory failure. High-flow oxygen via nasal cannula rapidly alleviates symptoms of acute respiratory failure and improves oxygenation by several mechanisms, including dead space washout, reduction in oxygen dilution and inspiratory nasopharyngeal resistance, a moderate positive airway pressure effect that may generate alveolar recruitment and an overall greater tolerance and comfort with the interface and the heated and humidified inspired gases. However, the experience in adults is still limited and there are no clinical guidelines to establish recommendations for their use. This article aims to review the existing evidence on the use of high-flow oxygen via nasal cannula in adults with acute respiratory failure and its possible applications, advantages and limitations. PMID:26429697

  5. Morphology impact on oxygen sensing ability of Ru(dpp)3Cl2 containing biocompatible polymers.

    PubMed

    Zhao, Susan Y; Harrison, Benjamin S

    2015-08-01

    Especially for tissue engineering applications, the diffusion of oxygen is a critical factor affecting spatial distribution and migration of cells. The cellular oxygen demand also fluctuates depending on tissue type and growth phase. Sensors that determine dissolved oxygen levels under biological conditions provide critical metabolic information about the growing cells as well as the state of the tissue culture within the tissue scaffold. This work focused on the effect of the scaffold morphology on the oxygen sensing response time. It was found that electrospun scaffolds had a faster oxygen-sensing response time than their bulk film counterparts. Tris-(4,7-diphenyl-1,10-phenanthroline) ruthenium (II) dichloride doped electrospun fiber mats of polycaprolactone (PCL) were found to be the most responsive to the presence of oxygen, followed by polyethylene (PEO) glycol mats. Systems containing poly vinyl alcohol were found to be the least responsive. This would suggest that, out of all the polymers tested, PCL and PEO are the most suitable biomaterials for oxygen-sensing applications. PMID:26042716

  6. Intrarenal and urinary oxygenation during norepinephrine resuscitation in ovine septic acute kidney injury.

    PubMed

    Lankadeva, Yugeesh R; Kosaka, Junko; Evans, Roger G; Bailey, Simon R; Bellomo, Rinaldo; May, Clive N

    2016-07-01

    Norepinephrine is the principal vasopressor used to restore blood pressure in sepsis, but its effects on intrarenal oxygenation are unknown. To clarify this, we examined renal cortical, medullary, and urinary oxygenation in ovine septic acute kidney injury and the response to resuscitation with norepinephrine. A renal artery flow probe and fiberoptic probes were placed in the cortex and medulla of sheep to measure tissue perfusion and oxygenation. A probe in the bladder catheter measured urinary oxygenation. Sepsis was induced in conscious sheep by infusion of Escherichia coli for 32 hours. At 24 to 30 hours of sepsis, either norepinephrine, to restore mean arterial pressure to preseptic levels or vehicle-saline was infused (8 sheep per group). Septic acute kidney injury was characterized by a reduction in blood pressure of ∼12 mm Hg, renal hyperperfusion, and oliguria. Sepsis reduced medullary perfusion (from an average of 1289 to 628 blood perfusion units), medullary oxygenation (from 32 to 16 mm Hg), and urinary oxygenation (from 36 to 24 mm Hg). Restoring blood pressure with norepinephrine further reduced medullary perfusion to an average of 331 blood perfusion units, medullary oxygenation to 8 mm Hg and urinary oxygenation to 18 mm Hg. Cortical perfusion and oxygenation were preserved. Thus, renal medullary hypoxia caused by intrarenal blood flow redistribution may contribute to the development of septic acute kidney injury, and resuscitation of blood pressure with norepinephrine exacerbates medullary hypoxia. The parallel changes in medullary and urinary oxygenation suggest that urinary oxygenation may be a useful real-time biomarker for risk of acute kidney injury. PMID:27165831

  7. Role of reactive oxygen and nitrogen species in acute respiratory distress syndrome.

    PubMed

    Fink, Mitchell P

    2002-02-01

    Reactive oxygen species are reactive, partially reduced derivatives of molecular oxygen (O 2 ). Important reactive oxygen species in biologic systems include superoxide radical anion, hydrogen peroxide, and hydroxyl radical. Closely related species include the hypohalous acids, particularly hypochlorous acid; chloramine and substituted chloramines; and singlet oxygen. Reactive nitrogen species are derived from the simple diatomic gas, nitric oxide. Peroxynitrite and its protonated form, peroxynitrous acid, are the most significant reactive nitrogen species in biologic systems. A variety of enzymatic and nonenzymatic processes can generate reactive oxygen species and reactive nitrogen species in mammalian cells. An extensive body of experimental evidence from studies using animal models supports the view that reactive oxygen species and reactive nitrogen species are important in the pathogenesis of acute respiratory distress syndrome. This view is further supported by data from clinical studies that correlate biochemical evidence of reactive oxygen species-mediated or reactive nitrogen species-mediated stress with the development of acute respiratory distress syndrome. Despite these data, pharmacologic strategies directed at minimizing reactive oxygen species-mediated or reactive nitrogen species-mediated damage have yet to be successfully introduced into clinical practice. The most extensively studied compound in this regard is N -acetylcysteine; unfortunately, clinical trials with this compound in patients with acute respiratory distress syndrome have yielded disappointing results. PMID:12205400

  8. 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

  9. Development of oxygen sensing in the gills of zebrafish.

    PubMed

    Jonz, Michael G; Nurse, Colin A

    2005-04-01

    Previous studies have described the morphology, innervation and O(2)-chemoreceptive properties of neuroepithelial cells (NECs) of the zebrafish gill filaments. The present work describes the ontogenesis of these cells, and the formation of functional O(2)-sensing pathways in developing zebrafish. Confocal immunofluorescence was performed on whole-mount gill preparations using antibodies against serotonin (5-HT) and a zebrafish-derived neuronal marker (zn-12) to identify the appearance and innervation of gill NECs during larval stages. NECs were first expressed in gill filament primordia of larvae at 5 days postfertilization (d.p.f.) and were fully innervated by 7 d.p.f. In vivo ventilation frequency analysis revealed that a behavioural response to hypoxia (11.2+/-2.8 min(-1)) developed in embryos as early as 2 d.p.f., and a significant increase (P<0.05) in the ventilatory response to hypoxia (200.8+/-23.0 min(-1)) coincided with innervation of NECs of the filaments. In addition, exogenous application of quinidine, a blocker of O(2)-sensitive background K(+) channels in NECs, induced hyperventilation in adults in a dose-dependent manner and revealed the development of a quinidine-sensitive ventilatory response in 7 d.p.f. larvae. This study shows that NEC innervation in the gill filaments may account for the development of a functional O(2)-sensing pathway and the hyperventilatory response to hypoxia in zebrafish larvae. At earlier stages, however, O(2)-sensing must occur through another pathway. The possibility that a new type of 5-HT-positive NEC of the gill arches may account for this earlier hypoxic response is discussed. PMID:15802677

  10. 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

  11. "Oxygen Sensing" by Na,K-ATPase: These Miraculous Thiols.

    PubMed

    Bogdanova, Anna; Petrushanko, Irina Y; Hernansanz-Agustín, Pablo; Martínez-Ruiz, Antonio

    2016-01-01

    Control over the Na,K-ATPase function plays a central role in adaptation of the organisms to hypoxic and anoxic conditions. As the enzyme itself does not possess O2 binding sites its "oxygen-sensitivity" is mediated by a variety of redox-sensitive modifications including S-glutathionylation, S-nitrosylation, and redox-sensitive phosphorylation. This is an overview of the current knowledge on the plethora of molecular mechanisms tuning the activity of the ATP-consuming Na,K-ATPase to the cellular metabolic activity. Recent findings suggest that oxygen-derived free radicals and H2O2, NO, and oxidized glutathione are the signaling messengers that make the Na,K-ATPase "oxygen-sensitive." This very ancient signaling pathway targeting thiols of all three subunits of the Na,K-ATPase as well as redox-sensitive kinases sustains the enzyme activity at the "optimal" level avoiding terminal ATP depletion and maintaining the transmembrane ion gradients in cells of anoxia-tolerant species. We acknowledge the complexity of the underlying processes as we characterize the sources of reactive oxygen and nitrogen species production in hypoxic cells, and identify their targets, the reactive thiol groups which, upon modification, impact the enzyme activity. Structured accordingly, this review presents a summary on (i) the sources of free radical production in hypoxic cells, (ii) localization of regulatory thiols within the Na,K-ATPase and the role reversible thiol modifications play in responses of the enzyme to a variety of stimuli (hypoxia, receptors' activation) (iii) redox-sensitive regulatory phosphorylation, and (iv) the role of fine modulation of the Na,K-ATPase function in survival success under hypoxic conditions. The co-authors attempted to cover all the contradictions and standing hypotheses in the field and propose the possible future developments in this dynamic area of research, the importance of which is hard to overestimate. Better understanding of the processes

  12. Role Of Hif2α Oxygen Sensing Pathway In Bronchial Epithelial Club Cell Proliferation

    PubMed Central

    Torres-Capelli, Mar; Marsboom, Glenn; Li, Qilong Oscar Yang; Tello, Daniel; Rodriguez, Florinda Melendez; Alonso, Tamara; Sanchez-Madrid, Francisco; García-Rio, Francisco; Ancochea, Julio; Aragonés, Julián

    2016-01-01

    Oxygen-sensing pathways executed by the hypoxia-inducible factors (HIFs) induce a cellular adaptive program when oxygen supply becomes limited. However, the role of the HIF oxygen-sensing pathway in the airway response to hypoxic stress in adulthood remains poorly understood. Here we found that in vivo exposure to hypoxia led to a profound increase in bronchial epithelial cell proliferation mainly confined to Club (Clara) cells. Interestingly, this response was executed by hypoxia-inducible factor 2α (HIF2α), which controls the expression of FoxM1, a recognized proliferative factor of Club cells. Furthermore, HIF2α induced the expression of the resistin-like molecules α and β (RELMα and β), previously considered bronchial epithelial growth factors. Importantly, despite the central role of HIF2α, this proliferative response was not initiated by in vivo Vhl gene inactivation or pharmacological inhibition of prolyl hydroxylase oxygen sensors, indicating the molecular complexity of this response and the possible participation of other oxygen-sensing pathways. Club cells are principally involved in protection and maintenance of bronchial epithelium. Thus, our findings identify a novel molecular link between HIF2α and Club cell biology that can be regarded as a new HIF2α-dependent mechanism involved in bronchial epithelium adaptation to oxygen fluctuations. PMID:27150457

  13. Remote sensing of atmospheric oxygen from a sounding rocket

    NASA Technical Reports Server (NTRS)

    Chakrabarti, S.; Cotton, D. M.; Lampton, M.; Siegmund, O. H. W.; Link, R.

    1988-01-01

    This paper describes a rocket experiment to investigate mechanisms governing the interactions between two of the fundamental components of the solar-terrestrial system: the solar ionizing radiation and the earth's upper atmosphere. The aim is to characterize the extreme ultraviolet (EUV) emissions resulting from these interactions in terms of physical parameters so that EUV remote sensing can be gainfully employed as a quantitative diagnostic of the terrestrial atmosphere and plasma environment. The payload consists of a high-resolution (about 0.5 A) spectrometer to measure the EUV emissions (980-1360 A) of the earth's dayglow, a moderate resolution (about 15 A) EUV spectrometer (250-1450 A) to measure the solar irradiation responsible for the photoelectron production, and a hydrogen Lyman Alpha photometer to monitor the solar irradiance and geocoronal emissions.

  14. 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. PMID:27499087

  15. Oxygen-Sensing Methods in Biomedicine from the Macroscale to the Microscale.

    PubMed

    Roussakis, Emmanuel; Li, Zongxi; Nichols, Alexander J; Evans, Conor L

    2015-07-13

    Oxygen monitoring has been a topic of exhaustive study given its central role in the biochemistry of life. The ability to quantify the physiological distribution and real-time dynamics of oxygen from sub-cellular to macroscopic levels is required to fully understand the mechanisms associated with both normal physiology and disease states. This Review will present the most significant recent advances in the development of oxygen-sensing materials and techniques, including polarographic, nuclear medicine, magnetic resonance, and optical approaches, that can be applied specifically for the real-time monitoring of oxygen dynamics in cellular and tissue environments. As some of the most exciting recent advances in synthetic methods and biomedical applications have been in the field of optical oxygen sensors, a major focus will be on the development of these toolkits. PMID:26084034

  16. Thickness Dependency of Thin Film Samaria Doped Ceria for Oxygen Sensing

    SciTech Connect

    Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Jiang, Weilin; Varga, Tamas; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

    2011-01-01

    High temperature oxygen sensors are widely used for exhaust gas monitoring in automobiles. This particular study explores the use of thin film single crystalline samaria doped ceria as the oxygen sensing material. Desired signal to noise ratio can be achieved in a material system with high conductivity. From previous studies it is established that 6 atomic percent samarium doping is the optimum concentration for thin film samaria doped ceria to achieve high ionic conductivity. In this study, the conductivity of the 6 atomic percent samaria doped ceria thin film is measured as a function of the sensing film thickness. Hysteresis and dynamic response of this sensing platform is tested for a range of oxygen pressures from 0.001 Torr to 100 Torr for temperatures above 673 K. An attempt has been made to understand the physics behind the thickness dependent conductivity behavior of this sensing platform by developing a hypothetical operating model and through COMSOL simulations. This study can be used to identify the parameters required to construct a fast, reliable and compact high temperature oxygen sensor.

  17. 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.

  18. Clinical Research in Acute Fatal Illness: Lessons From Extracorporeal Membrane Oxygenation.

    PubMed

    Bartlett, Robert H

    2016-08-01

    Clinical research to evaluate the effectiveness of life support systems in acute fatal illness has unique problems of logistics, ethics, and consent. There have been 10 prospective comparative trials of extracorporeal membrane oxygenation in acute fatal respiratory failure, utilizing different study designs. The trial designs were prospective controlled randomized, prospective adaptive randomized, sequential, and matched pairs. The trials were reviewed with regard to logistics, ethics, consent, statistical methods, economics, and impact. The matched pairs method is the best study design for evaluation of life support systems in acute fatal illness. PMID:25223826

  19. Acute carbon monoxide poisoning: Emergency management and hyperbaric oxygen therapy

    SciTech Connect

    Severance, H.W.; Kolb, J.C.; Carlton, F.B.; Jorden, R.C.

    1989-10-01

    An ice storm in February 1989 resulted in numerous incidences of carbon monoxide poisoning in central Mississippi secondary to exposure to open fires in unventilated living spaces. Sixteen cases were treated during this period at the University of Mississippi Medical Center and 6 received Hyperbaric Oxygen therapy. These 6 cases and the mechanisms of CO poisoning are discussed and recommendations for emergency management are reviewed.10 references.

  20. 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, ...

  1. A mechanism of oxygen sensing in yeast. Multiple oxygen-responsive steps in the heme biosynthetic pathway affect Hap1 activity.

    PubMed

    Hon, Thomas; Dodd, Athena; Dirmeier, Reinhard; Gorman, Nadia; Sinclair, Peter R; Zhang, Li; Poyton, Robert O

    2003-12-12

    Heme plays central roles in oxygen sensing and utilization in many living organisms. In yeast, heme mediates the effect of oxygen on the expression of many genes involved in using or detoxifying oxygen. However, a direct link between intracellular heme level and oxygen concentration has not been vigorously established. In this report, we have examined the relationships among oxygen levels, heme levels, Hap1 activity, and HAP1 expression. We found that Hap1 activity is controlled in vivo by heme and not by its precursors and that heme activates Hap1 even in anoxic cells. We also found that Hap1 activity exhibits the same oxygen dose-response curves as Hap1-dependent aerobic genes and that these dose-response curves have a sharp break at approximately 1 microM O2. The results show that the intracellular signaling heme level, reflected as Hap1 activity, is closely correlated with oxygen concentration. Furthermore, we found that bypass of all heme synthetic steps but ferrochelatase by deuteroporphyrin IX does not circumvent the need for oxygen in Hap1 full activation by heme, suggesting that the last step of heme synthesis, catalyzed by ferrochelatase, is also subjected to oxygen control. Our results show that multiple heme synthetic steps can sense oxygen concentration and provide significant insights into the mechanism of oxygen sensing in yeast. PMID:14512429

  2. Two–Photon Oxygen Sensing with Quantum Dot–Porphyrin Conjugates

    PubMed Central

    Lemon, Christopher M.; Karnas, Elizabeth; Bawendi, Moungi G.; Nocera, Daniel G.

    2013-01-01

    Supramolecular assemblies of a quantum dot (QD) associated to palladium(II) porphyrins have been developed to detect oxygen (pO2) in organic solvents. Palladium porphyrins are sensitive in the 0–160 torr range, making them ideal phosphors for in vivo biological oxygen quantification. Porphyrins with meso pyridyl substituents bind to the surface of the QD to produce self–assembled nanosensors. Appreciable overlap between QD emission and porphyrin absorption features results in efficient Förster resonance energy transfer (FRET) for signal transduction in these sensors. The QD serves as a photon antenna, enhancing porphyrin emission under both one– and two–photon excitation, demonstrating that QD–palladium porphyrin conjugates may be used for oxygen sensing over physiological oxygen ranges. PMID:23978247

  3. Preparation, characterization and oxygen sensing properties of luminescent carbon dots assembled mesoporous silica microspheres.

    PubMed

    Wang, Li; Zhang, Haoran; Zhou, Xiaohua; Liu, Yingliang; Lei, Bingfu

    2016-09-15

    In this paper, our effort was focused on preparation and oxygen sensing of luminescence carbon dots (CDs) assembled hollow mesoporous silica microspheres (HMSMs) and mesoporous silica microspheres (MSMs). MSMs doped with CDs showed shorter response time and recovery time comparing with HMSMs doped with CDs. This feature can be attributed to ordered channel structure of mesoporous carrier which can promote the gas diffusion effectively. While HMSMs doped with CDs shows a higher oxygen quenching response and the degree of quenching reach 80.35%. The response time was determined to be about 7s and the emission intensities of the samples were effectively reduced as the concentration of oxygen increased. These results indicate that the system we have developed can be used for oxygen detection in wide concentration range and is especially accurate for very low oxygen concentrations. The obtained CDs grafted hollow mesoporous silica microspheres (HMSMs) and mesoporous silica microspheres (MSMs) samples appears to be a promising sensing material for environmental detection application and would also find applications in catalyst, electrode, or related fields. PMID:27309945

  4. Remote Sensing of Dissolved Oxygen and Nitrogen in Water using Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    De Young, R.; Ganoe, R.

    2013-12-01

    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 experiment has demonstrated the ability to remotely detect dissolved oxygen and nitrogen in pure water (also Chesapeake Bay water) using a 355nm Nd:YAG laser and a simple monochromater to detect the shifted Raman oxygen and nitrogen backscattered signals at 376.2 and 387.5 nm respectively. The theoretical basis for the research, components of the experimental system, and key findings are presented. A 1.3-m water cell had an attached vertical column to house a Troll 9500 dissolved oxygen in-situ monitor (In-Situ Inc Troll 9500). The Raman oxygen signal could be calibrated with this devise. While Raman backscattered water signals are low a potential aircraft remote system was designed and will be presented.

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

    PubMed

    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

  6. High-flow nasal cannula oxygen therapy for acute exacerbation of interstitial pneumonia: A case series.

    PubMed

    Horio, Yukihiro; Takihara, Takahisa; Niimi, Kyoko; Komatsu, Masamichi; Sato, Masako; Tanaka, Jun; Takiguchi, Hiroto; Tomomatsu, Hiromi; Tomomatsu, Katsuyoshi; Hayama, Naoki; Oguma, Tsuyoshi; Aoki, Takuya; Urano, Tetsuya; Takagi, Atsushi; Asano, Koichiro

    2016-03-01

    We report 3 cases (all men, age: 69-81 years) of acute exacerbation of interstitial pneumonia (AEIP) that were successfully treated with a high-flow nasal cannula (HFNC), which delivers heated, humidified gas at a fraction of inspired oxygen (FIO2) up to 1.0 (100%). Oxygenation was insufficient under non-rebreathing face masks; however, the introduction of HFNC with an FIO2 of 0.7-1.0 (flow rate: 40L/min) improved oxygenation and was well-tolerated until the partial pressure of oxygen in blood/FIO2 ratio increased (between 21 and 26 days). Thus, HFNC might be an effective and well-tolerated therapeutic addition to the management of AEIP. PMID:26879483

  7. FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

    2005-07-01

    A reflection mode fiber optic oxygen sensor is being developed that can operate at high temperatures for power plant applications. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Two critical materials issues are the cluster's ability to withstand high temperatures when immobilized in a porous the sol-gel support, and whether after heating to high temperatures, the sol-gel matrix maintains a high and constant permeability to oxygen to support rapid quenching of luminescence. We used a composite materials approach to prepare stable sensing layers on optical fibers. We dispersed 60 w/w% of a pre-cured sol-gel composite containing the potassium salt of molybdenum clusters (K{sub 2}Mo{sub 6}Cl{sub 14}) into a sol-gel binder solution, and established the conditions necessary for deposition of sol-gel films on optical fibers and planar substrates. The fiber sensor has an output signal of 5 nW when pumped with an inexpensive commercial 365 nm ultraviolet light emitting diode (LED). Quenching of the sensor signal by oxygen was observed up to a gas temperature of 175 C with no degradation of the oxygen permeability of the composite after high temperature cycling. On planar substrates the cluster containing composite responds within <1 second to a gas exchange from nitrogen to oxygen, indicating the feasibility of real-time oxygen detection.

  8. A paradigm shift in oxygen sensing with a twist in the tale!

    PubMed

    O'Halloran, Ken D

    2016-09-01

    AMP-activated protein kinase (AMPK) is pivotal to metabolic homoeostasis in eukaryotes, serving as a critical energy sensor. Increased AMPK activity during oxygen deprivation (hypoxia) protects against potentially catastrophic deficits in ATP supply. Although the nervous system circuitry for elaboration of the complex cardiorespiratory response to hypoxia has been understood in some detail for many decades, there is continued and considerable interest in the molecular machinery underpinning the mechanism(s) of oxygen sensing. In this issue of the Biochemical Journal, Evans et al. [(2016) Biochem. J.] review their recent work, which points to a pivotal role for AMPK in the transduction of cellular hypoxic stress to integrated ventilatory behaviour, critical in the defence of whole-body oxygen homoeostasis. Of great surprise, there is profound blunting of the hyperventilatory response to hypoxic stress in AMPK deficient mice, with resultant dysregulated breathing arising in spite of normal peripheral oxygen sensing and appropriate sensory input to the brain! Their pointedly provocative review challenges current dogma, and in doing so raises intriguing questions that probe fundamental aspects of our understanding of the mammalian ventilatory response to hypoxic stress. The engaging review by Evans et al. [(2016) Biochem. J.] is an interesting read that is sure to encourage colourful debate. PMID:27574024

  9. Fabrication of Eu(III) complex doped nanofibrous membranes and their oxygen-sensing properties

    NASA Astrophysics Data System (ADS)

    Songzhu, Lin; Xiangting, Dong; Jinxian, Wang; Guixia, Liu; Wenshen, Yu; Ruokun, Jia

    2010-11-01

    In this paper, we report the synthesis, characterization, and photophysical properties of Eu(TTA) 3ECIP, where TTA = 2-thenoyltrifluoroacetonate, and ECIP = 1-ethyl-2-(N-ethyl-carbazole-yl-4-)imidazo[4,5-f]1,10-phenanthroline. Its elementary application for oxygen-sensing application is also investigated by doping it into a polymer matrix of polystyrene (PS). Experimental data suggest that the 2.5 wt% doped Eu(TTA) 3ECIP/PS nanofibrous membrane exhibits a high sensitivity of 3.4 towards oxygen with a good linear relationship of R2 = 0.9962. In addition, the 2.5 wt% doped Eu(TTA) 3ECIP/PS nanofibrous membrane owns a quick response of 8 s towards oxygen, along with its excellent atmosphere insensitivity and photobleaching resistance. All these results suggest that both Eu(TTA) 3ECIP and Eu(TTA) 3ECIP/PS system are promising candidates for oxygen-sensing optical sensors.

  10. Synthesis, characterization, photophysical and oxygen-sensing properties of a novel europium(III) complex

    NASA Astrophysics Data System (ADS)

    Feng, Nan; Xie, Jing; Zhang, Dawei

    2010-09-01

    In this paper, we report the synthesis, characterization, crystal structure, and photophysical properties of a novel Eu 3+ complex of Eu(DBM) 3IPD, where DBM = 1,3-diphenyl-propane-1,3-dione and IPD = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline. Its elementary application for oxygen-sensing application is also investigated by doping it into a silica matrix of MCM-41. Experimental data suggest that the 20 mg/g doped Eu(DBM) 3IPD/MCM-41 system exhibits a high sensitivity of 3.6 towards molecular oxygen with a good linear relationship of R2 = 0.9987. In addition, the 20 mg/g doped Eu(DBM) 3IPD/MCM-41 system owns a quick response of 8 s towards oxygen, along with its excellent atmosphere insensitivity and photobleaching resistance. All these results suggest that both Eu(DBM) 3IPD and Eu(DBM) 3IPD/MCM-41 systems are promising candidates for oxygen-sensing optical sensors.

  11. Facet effects of palladium nanocrystals for oxygen reduction in ionic liquids and for sensing applications

    NASA Astrophysics Data System (ADS)

    Tang, Yongan; Chi, Xiaowei; Zou, Shouzhong; Zeng, Xiangqun

    2016-03-01

    Palladium nanocrystals enclosed by {100} and {110} crystal facets, were successfully synthesized through an aqueous one-pot synthesis method. A new thermal annealing approach was developed for fabricating these palladium nanocrystals as a working electrode on a gas permeable membrane to study the facet effects of the oxygen reduction process in an ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Bmpy][NTf2]). Results were compared with the same processes at a conventional platinum electrode. Our study shows that the structural difference between the two facets of Pd nanocrystals has little effect on the oxygen reduction process but significantly affects the oxidation process of the superoxide. It is found that the Pd{110}/IL interface can better stabilize superoxide radicals revealed by a more positive oxidation potential compared to that of Pd{100}. In addition, the analytical characteristic of utilizing both palladium nanocrystals as electrodes for oxygen sensing is comparable with a polycrystal platinum oxygen sensor, in which Pd{110} presents the best sensitivity and lowest detection limit. Our results demonstrate the facet-dependence of oxygen reduction in an ionic liquid medium and provide the fundamental information needed to guide the applications of palladium nanocrystals in electrochemical gas sensor and fuel cell research.Palladium nanocrystals enclosed by {100} and {110} crystal facets, were successfully synthesized through an aqueous one-pot synthesis method. A new thermal annealing approach was developed for fabricating these palladium nanocrystals as a working electrode on a gas permeable membrane to study the facet effects of the oxygen reduction process in an ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Bmpy][NTf2]). Results were compared with the same processes at a conventional platinum electrode. Our study shows that the structural difference between the two facets of Pd

  12. 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

  13. Acute transient non-physiological over-sensing in the ventricle with a DF4 lead

    PubMed Central

    Ng, Kevin Kit; Gould, Paul A.

    2015-01-01

    The DF-4 is a new defibrillator lead technology. We present two cases of non-physiological transient ventricular over-sensing in patients who underwent implantation of an ICD for secondary prevention. Case 1 had ventricular over-sensing during pacing threshold evaluation post defibrillation testing while Case 2 had the lead integrity alert triggered immediately post discharge with transient over-sensing. No lead-connector issues were found. Case 1 was likely due to improper venting of the header and trapped air. Case 2 was hypothesized to be due to intermittent header pin non-contact secondary to blood in the header. These cases reveal that DF-4 leads are subject to both reported and potentially novel causes of transient acute ventricular over-sensing. PMID:26937124

  14. Acute Variations in Retinal Vascular Oxygen Content in a Rabbit Model of Retinal Venous Occlusion

    PubMed Central

    Saati, Saloomeh; Martin, Gabriel; Chader, Gerald; Humayun, Mark S.

    2012-01-01

    Purpose To study the variation in intravascular oxygen saturation (oximetry) during an acute retinal vein occlusion (RVO) using hyperspectral computed tomographic spectroscopy based oximetry measurements. Methods Thirty rabbits were dilated and anesthetized for experiments. Baseline oximetry measurements were made using a custom-made hyperspectral computed tomographic imaging spectrometer coupled to a fundus camera. RVO were induced using argon green laser following an intravenous injection of Rose Bengal. RVO induction was confirmed by fluorescein angiography. Retinal oximetry measurements were repeated in arterial and venous branches one hour after RVO induction and up to 4 weeks afterwards. Comparison of retinal oximetry before and after vein occlusion was made using the Student T-test. Results One hour after RVO induction, we observed statistically significant reductions in the intravascular oxygen saturation in temporal retinal arteries (85.1±6.1% vs. 80.6±6.6%; p<0.0001) and veins (71.4±5.5% vs. 64.0±4.7%; p<0.0001). This decrease was reversible in animals that spontaneously recannulated the vein occlusion. There were no statistically significant differences in oxygen saturation in the nasal control arteries and veins before and after temporal vein RVO induction. Conclusions We demonstrate, for the first time, acute changes in the intravascular oxygen content of retinal vessels 1 hour after RVO. These changes are reversible upon spontaneous recannulation of retinal vessels. This study demonstrates that hyperspectral computer tomographic spectroscopy based oximetry can detect physiological variations in intravascular retinal oxygen saturation. The study also provides the first qualitative and quantitative evidence of the variation in retinal vascular oxygen content directly attributable to an acute retinal vein occlusion. PMID:23185567

  15. 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

  16. Regulation of carotid body oxygen sensing by hypoxia-inducible factors.

    PubMed

    Prabhakar, Nanduri R; Semenza, Gregg L

    2016-01-01

    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

  17. Extracorporeal membrane oxygenation for the treatment of adult sickle cell acute chest syndrome.

    PubMed

    Parhar, Ken; Parizkova, Barbora; Jones, Nicola; Valchanov, Kamen; Fowles, Jo-Anne; Besser, Martin; Telfer, Paul; Kaya, Banu; Vuylsteke, Alain; Rubino, Antonio

    2016-04-01

    Sickle cell disease (SCD) is a hereditary haemoglobinopathy that results in polymerization of haemoglobin molecules and subsequent vaso-occlusion. A common cause of death in adults is acute chest syndrome (AChS) with resulting hypoxemic respiratory failure.Veno-venous extracorporeal membrane oxygenation (VV-ECMO) has been used successfully in acutely reversible respiratory failure when conventional mechanical ventilation has been unable to adequately oxygenate and ventilate in a lung-protective fashion.We present an adult SCD patient with severe respiratory failure due to AChS, successfully treated with VV-ECMO. We also discuss some of the technical challenges and considerations when using ECMO in the SCD patient. PMID:26130498

  18. A New Crosslinkable Oxygen Sensor Covalently Bonded into Poly(2-hydroxyethyl methacrylate)-CO-Polyacrylamide Thin Film for Dissolved Oxygen Sensing

    PubMed Central

    Tian, Yanqing; Shumway, Bradley R.; Meldrum, Deirdre R.

    2010-01-01

    A new oxygen sensor, compound 2, was synthesized through a chemical modification of a popularly used oxygen sensor of platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin (PtTFPP). The new sensor compound 2 possesses four crosslinkable methacrylate functional moieties, enabling it to be polymerized and crosslinked with other monomers for polymer sensing film (also called membrane) preparation. Using this characteristic, compound 2 was covalently bonded to hydrophilic poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (referred to as PHEMA to simplify) and hydrophobic polystyrene (PS) films. To better understand the advantages and disadvantages of chemical crosslinking approaches and the influence of polymer matrices on sensing performance, PtTFPP was physically incorporated into the same PHEMA and PS matrices to compare. Response to dissolved oxygen (DO), leaching of the sensor molecules from their matrices, photostability of the sensors, and response time to DO changes were studied. It was concluded that the chemical crosslinking of the sensor compound 2 in polymer matrices: (i) alleviated the leaching problem of sensor molecules which usually occurred in the physically doped sensing systems and (ii) significantly improved sensors’ photostability. The PHEMA matrix was demonstrated to be more suitable for oxygen sensing than PS, because for the same sensor molecule, the oxygen sensitivity in PHEMA film was higher than that in PS and response time to DO change in the PHEMA film was faster than that in PS. It was the first time oxygen sensing films were successfully prepared using biocompatible hydrophilic PHEMA as a matrix, which does not allow leaching of the sensor molecules from the polymer matrix, has a faster response to DO changes than that of PS, and does not present cytotoxicity to human lung adenocarcinoma epithelial cells (A549). It is expected that the new sensor compound 2 and its similar compounds with chemically crosslinking

  19. 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

  20. The human carotid body transcriptome with focus on oxygen sensing and inflammation – a comparative analysis

    PubMed Central

    Mkrtchian, Souren; Kåhlin, Jessica; Ebberyd, Anette; Gonzalez, Constancio; Sanchez, Diego; Balbir, Alexander; Kostuk, Eric W; Shirahata, Machiko; Fagerlund, Malin Jonsson; Eriksson, Lars I

    2012-01-01

    The carotid body (CB) is the key oxygen sensing organ. While the expression of CB specific genes is relatively well studied in animals, corresponding data for the human CB are missing. In this study we used five surgically removed human CBs to characterize the CB transcriptome with microarray and PCR analyses, and compared the results with mice data. In silico approaches demonstrated a unique gene expression profile of the human and mouse CB transcriptomes and an unexpected upregulation of both human and mouse CB genes involved in the inflammatory response compared to brain and adrenal gland data. Human CBs express most of the genes previously proposed to be involved in oxygen sensing and signalling based on animal studies, including NOX2, AMPK, CSE and oxygen sensitive K+ channels. In the TASK subfamily of K+ channels, TASK-1 is expressed in human CBs, while TASK-3 and TASK-5 are absent, although we demonstrated both TASK-1 and TASK-3 in one of the mouse reference strains. Maxi-K was expressed exclusively as the spliced variant ZERO in the human CB. In summary, the human CB transcriptome shares important features with the mouse CB, but also differs significantly in the expression of a number of CB chemosensory genes. This study provides key information for future functional investigations on the human carotid body. PMID:22615433

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  2. Water-soluble phosphorescent ruthenium complex with a fluorescent coumarin unit for ratiometric sensing of oxygen levels in living cells.

    PubMed

    Hara, Daiki; Komatsu, Hirokazu; Son, Aoi; Nishimoto, Sei-Ichi; Tanabe, Kazuhito

    2015-04-15

    Dual emission was applied to a molecular probe for the ratiometric sensing of oxygen concentration in a living system. We prepared ruthenium complexes possessing a coumarin unit (Ru-Cou), in which the (3)MLCT phosphorescence of the ruthenium complex was efficiently quenched by molecular oxygen, whereas the coumarin unit emitted constant fluorescence independent of the oxygen concentration. The oxygen status could be determined precisely from the ratio of phosphorescence to fluorescence. We achieved the molecular imaging of cellular oxygen levels using Ru-Cou possessing an alkyl chain, which provided appropriate lipophilicity to increase cellular uptake. PMID:25848851

  3. Fiber-Based Laser Transmitter for Oxygen A-Band Spectroscopy and Remote Sensing

    NASA Technical Reports Server (NTRS)

    Stephen, Mark A.; Abshire, James B.

    2010-01-01

    A fiber-based laser transmitter has been designed for active remote-sensing spectroscopy. The transmitter uses a master-oscillator-power-amplifier (MOPA) configuration with a distributed feedback diode-laser master oscillator and an erbium-doped fiber amplifier. The output from the MOPA is frequency-doubled with a periodically poled nonlinear crystal. The utility of this single-frequency, wavelength-tunable, power-scalable laser has been demonstrated in a spectroscopic measurement of the diatomic oxygen A-band.

  4. Diversity of Magneto-Aerotactic Behaviors and Oxygen Sensing Mechanisms in Cultured Magnetotactic Bacteria

    PubMed Central

    Lefèvre, Christopher T.; Bennet, Mathieu; Landau, Livnat; Vach, Peter; Pignol, David; Bazylinski, Dennis A.; Frankel, Richard B.; Klumpp, Stefan; Faivre, Damien

    2014-01-01

    Microorganisms living in gradient environments affect large-scale processes, including the cycling of elements such as carbon, nitrogen or sulfur, the rates and fate of primary production, and the generation of climatically active gases. Aerotaxis is a common adaptation in organisms living in the oxygen gradients of stratified environments. Magnetotactic bacteria are such gradient-inhabiting organisms that have a specific type of aerotaxis that allows them to compete at the oxic-anoxic interface. They biomineralize magnetosomes, intracellular membrane-coated magnetic nanoparticles, that comprise a permanent magnetic dipole that causes the cells to align along magnetic field lines. The magnetic alignment enables them to efficiently migrate toward an optimal oxygen concentration in microaerobic niches. This phenomenon is known as magneto-aerotaxis. Magneto-aerotaxis has only been characterized in a limited number of available cultured strains. In this work, we characterize the magneto-aerotactic behavior of 12 magnetotactic bacteria with various morphologies, phylogenies, physiologies, and flagellar apparatus. We report six different magneto-aerotactic behaviors that can be described as a combination of three distinct mechanisms, including the reported (di-)polar, axial, and a previously undescribed mechanism we named unipolar. We implement a model suggesting that the three magneto-aerotactic mechanisms are related to distinct oxygen sensing mechanisms that regulate the direction of cells’ motility in an oxygen gradient. PMID:25028894

  5. Acute ethanol induces apoptosis by stimulating TRPC6 via elevation of superoxide in oxygenated podocytes.

    PubMed

    Lu, Xiao-Yu; Liu, Bing-Chen; Wang, Li-Hua; Yang, Li-Li; Bao, Qing; Zhai, Yu-Jia; Alli, Abdel A; Thai, Tiffany L; Eaton, Douglas C; Wang, Wei-Zhi; Ma, He-Ping

    2015-05-01

    Our recent studies indicate that hydrogen peroxide (H2O2) only at high concentrations can cause oxidative stress in renal epithelial cells and induce apoptosis of podocytes. Consistently, the present study shows that H2O2, even at 1 mM, failed to induce intracellular oxidative stress and apoptosis of the podocytes due to efficient activity of catalase, an enzyme which degrades H2O2 to produce water and oxygen (O2). However, H2O2 acted as a source of O2 to allow acute ethanol to induce superoxide production and cause apoptosis of the podocytes. In contrast, acute ethanol alone did not elevate intracellular superoxide, even though it stimulates expression and translocation of p47phox to the plasma membrane. Inhibition of catalase abolished not only O2 production from H2O2 degradation, but also NOX2-dependent superoxide production in the podocytes challenged by both H2O2 and acute ethanol. In parallel, acute ethanol in the presence of H2O2, but neither ethanol nor H2O2 alone, stimulated transient receptor potential canonical 6 (TRPC6) channels and caused TRPC6-dependent elevation of intracellular Ca2+. These data suggest that exogenous H2O2 does not induce oxidative stress due to rapid degradation to produce O2 in the podocytes, but the oxygenated podocytes become sensitive to acute ethanol challenge and undergo apoptosis via a TRPC6-dependent elevation of intracellular Ca2+. Since cultured podocytes are considered in hypoxic conditions, H2O2 may be used as a source of O2 to establish an ischemia-reperfusion model in some type of cultured cells in which H2O2 does not directly induce intracellular oxidative stress. PMID:25601712

  6. Oxygen sensing in neuroendocrine cells and other cell types: pheochromocytoma (PC12) cells as an experimental model.

    PubMed

    Spicer, Zachary; Millhorn, David E

    2003-01-01

    A steady supply of oxygen is an absolute requirement for mammalian cells to maintain normal cellular functions. To answer the challenge that oxygen deprivation represents, mammals have evolved specialized cell types that can sense changes in oxygen tension and alter gene expression to enhance oxygen delivery to hypoxic areas. These oxygensensing cells are rare and difficult to study in vivo. As a result, pheochromocytoma (PC12) cells have become a vital in vitro model system for deciphering the molecular events that confer the hypoxia-resistant and oxygen-sensing phenotypes. Research over the last few years has revealed that the hypoxia response in PC12 cells involves the interactions of several signal transduction pathways (Ca2+/calmodulin-dependent kinases, Akt, SAPKs, and MAPKs) and transcription factors (HIFs, CREB, and c-fos/junB). This review summarizes the current understanding of the role these signal transduction pathways and transcription factors play in determining the hypoxic response. PMID:14739486

  7. Relationship between the microscopic and macroscopic world in optical oxygen sensing: a luminescence lifetime microscopy study.

    PubMed

    López-Gejo, Juan; Haigh, David; Orellana, Guillermo

    2010-02-01

    An investigation based on confocal fluorescence lifetime imaging microscopy (FLIM) of silica-loaded silicone films doped with a molecular oxygen-sensitive ruthenium(II) polyazaheterocyclic complex is presented. The effect of the silica type (hydrophilic/hydrophobic), particle size and amount of silica filler on the luminescence decay of the immobilized indicator dye has thoroughly been studied. A higher amount of hydrophilic silica leads to both a higher solubility of molecular oxygen into the silicone film and to higher levels of the metal indicator dye. Thus, incorporation of 10% (by wt) pyrogenic silica into silicone shortens the mean luminescence lifetime from 1.4 to 0.9 micros. However, an excess of filler may lead to overloading of the dye into the film producing new phenomena such as triplet-triplet annihilation and excitation energy homotransfer, as observed from their influence on the emission lifetime of the metal complex. Those phenomena do not take place when trimethylated silica (hydrophobic filler) is used. In this case, no increase on the oxygen or dye concentration is observed after addition of the filler and no significant reduction of the luminescence lifetime is measured. Both the addition of silica and the possible precipitation of dye crystals lead to the appearance of microdomains where the molecular probe exhibits widely different excited state lifetimes. For the first time, such microdomains within the oxygen sensing layer are visualized and analyzed by means of FLIM, showing the potential of this technique and the usefulness of our conclusions to the future design and development of novel luminescent oxygen sensor films for environmental and process analysis. PMID:20099927

  8. Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D. J. Osborn; Po Zhang

    2006-09-30

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications has been developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. We report on a fiber optic technique for detection of gas phase oxygen up to 100 C based on the {sup 3}O{sub 2} quenching of the luminescence from molybdenum chloride clusters, K{sub 2}Mo{sub 6}Cl{sub 14}. The inorganic sensing film is a composite of sol-gel particles embedded in a thin, oxygen permeable sol-gel binder. The particles are comprised of thermally stable, luminescent K{sub 2}Mo{sub 6}Cl{sub 14} clusters dispersed in a fully equilibrated sol-gel matrix. From 40 to 100 C, the fiber sensor switches {approx}6x in intensity in response to alternating pulses of <0.001% O2 and 21% O{sub 2} between two well defined levels with a response time of 10 s. The sensor signal is a few nW for an input pump power of 250 {micro}W. The normalized sensor signal is linear with molar oxygen concentration and fits the theoretical Stern-Volmer relationship. Although the sensitivity decreases with temperature, sensitivity at 100 C is 160 [O{sub 2}]{sup -1}. These parameters are well suited for in-situ, real-time monitoring of oxygen for industrial process control applications.

  9. Enhanced gas sensing performance of Li-doped ZnO nanoparticle film by the synergistic effect of oxygen interstitials and oxygen vacancies

    NASA Astrophysics Data System (ADS)

    Zhao, Jianwei; Xie, Changsheng; Yang, Li; Zhang, Shunping; Zhang, Guozhu; Cai, Ziming

    2015-03-01

    Li doped ZnO (Zn1-xLixO) nanoparticles with different content were synthesized. X-ray photoelectron spectroscopy (XPS) indicated that the ratio of oxygen to zinc for ZnO increased with increasing of Li content from x = 0 to 0.2, which had been attributed to the introduction of oxygen interstitial by Li dopant. The sensing performance and the temperature-dependent conductivity were investigated. It is observed that Li doped ZnO showed higher sensitivity and selectivity compared to the undoped ZnO. The 0.1 Li doped ZnO performed the maximum responses of 71.5 and 40.2 for 100 ppm methanol and formaldehyde, respectively, at 350 °C. The research showed that the oxygen vacancies served as active sites which supported the oxygen adsorption and reaction, oxygen interstitials served as active sites to oxidize the reducing gases and produce electrons. The enhanced sensing performance of Li doped ZnO was attributed to the synergistic effect of oxygen interstitials and oxygen vacancies.

  10. Oxygen saturation changes in the optic nerve head during acute intraocular pressure elevation in monkeys

    NASA Astrophysics Data System (ADS)

    Khoobehi, Bahram; Kawano, Hiroyuki; Ning, Jinfeng; Burgoyne, Claude F.; Rice, David A.; Khan, Fareeha; Thompson, Hilary W.; Beach, James M.

    2009-02-01

    Background and Objective: To evaluate the effect of an acute elevated intraocular pressure (IOP) on oxygen saturation of structures of the optic nerve head. Study Design/Materials and Methods: In the cynomolgus monkey eye, IOP was set to 10 mm Hg, and then raised to 30, 45, and 55 mm Hg. The ONH and overlying vessels were imaged using a fundus camera attached to a hyperspectral imaging system (HSI) at 10 and 30 minutes after IOP elevation. Results: Raising IOP from 10 to 30 mm Hg did not significantly (P < 0.0001) change saturation in vessels or ONH tissue structures but at 55 mm Hg, all structures showed significant reduction. Conclusions: Quantitative assay of the blood oxygen saturation in structures on the surface and overlying the optic nerve head is possible using hyperspectral imaging techniques.

  11. Should hyperbaric oxygen be used to treat the pregnant patient for acute carbon monoxide poisoning

    SciTech Connect

    Van Hoesen, K.B.; Camporesi, E.M.; Moon, R.E.; Hage, M.L.; Piantadosi, C.A. )

    1989-02-17

    Carbon monoxide (CO) is the leading cause of death due to poisoning. Although uncommon, CO poisoning does occur during pregnancy and can result in fetal mortality and neurological malformations in fetuses who survive to term. Uncertainty arises regarding the use of hyperbaric oxygen (HBO) as a treatment for the pregnant patient because of possible adverse effects on the fetus that could be induced by oxygen at high partial pressures. While the dangers of hyperoxia to the fetus have been demonstrated in animal models, careful review of animal studies and human clinical experience indicates that the short duration of hyperoxic exposure attained during HBO therapy for CO poisoning can be tolerated by the fetus in all stages of pregnancy and reduces the risk of death or deformity to the mother and fetus. A case is presented of acute CO poisoning during pregnancy that was successfully treated with HBO. Recommendations are suggested for the use of HBO during pregnancy.

  12. Acute and chronic effects of atmospheric oxygen on the feeding behavior of Drosophila melanogaster larvae.

    PubMed

    Farzin, Manoush; Albert, Todd; Pierce, Nicholas; VandenBrooks, John M; Dodge, Tahnee; Harrison, Jon F

    2014-09-01

    All insects studied to date show reduced growth rates in hypoxia. Drosophila melanogaster reared in moderate hypoxia (10 kPa PO2) grow more slowly and form smaller adults, but the mechanisms responsible are unclear, as metabolic rates are not oxygen-limited. It has been shown that individual fruit flies do not grow larger in hyperoxia (40 kPa PO2), but populations of flies evolve larger size. Here we studied the effect of acute and chronic variation in atmospheric PO2 (10, 21, 40 kPa) on feeding behavior of third instar larvae of D.melanogaster to assess whether oxygen effects on growth rate can be explained by effects on feeding behavior. Hypoxic-reared larvae grew and developed more slowly, and hyperoxic-rearing did not affect growth rate, maximal larval mass or developmental time. The effect of acute exposure to varying PO2 on larval bite rates matched the pattern observed for growth rates, with a 22% reduction in 10 kPa PO2 and no effect of 40 kPa PO2. Chronic rearing in hypoxia had few effects on the responses of feeding rates to oxygen, but chronic rearing in hyperoxia caused feeding rates to be strongly oxygen-dependent. Hypoxia produced similar reductions in bite rate and in the volume of tunnels excavated by larvae, supporting bite rate as an index of feeding behavior. Overall, our data show that reductions in feeding rate can explain reduced growth rates in moderate hypoxia for Drosophila, contributing to reduced body size, and that larvae cannot successfully compensate for this level of hypoxia with developmental plasticity. PMID:25008193

  13. 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. PMID:26630309

  14. Ventilation-perfusion mismatching in acute severe asthma: effects of salbutamol and 100% oxygen.

    PubMed Central

    Ballester, E; Reyes, A; Roca, J; Guitart, R; Wagner, P D; Rodriguez-Roisin, R

    1989-01-01

    Ventilation-perfusion (VA/Q) relationships and gas exchange were studied by the multiple inert gas technique in 19 patients admitted to hospital with acute severe asthma (FEV1 41% predicted) before and during the administration of intravenous salbutamol, inhaled salbutamol, or 100% oxygen. Eight patients received a continuous intravenous infusion of salbutamol (4 micrograms/min, total dose 360 micrograms) and were studied before treatment, after 60 and 90 minutes of treatment, and one hour after treatment had been discontinued. Six patients had measurements before and 15 minutes after inhaling 300 micrograms salbutamol from a metered dose inhaler on two occasions (total dose 600 micrograms) and one hour after the last dose. Measurements were also made in five patients before and while they breathed 100% oxygen for 20 minutes. At baseline (fractional inspired oxygen (FiO2) 21%) all patients showed a broad unimodal (n = 10) or bimodal (n = 9) distribution of blood flow with respect to VA/Q. A mean of 10.5% of the blood flow was associated with low VA/Q units without any appreciable shunt. One of the best descriptors of VA/Q inequality, the second moment of the perfusion distribution on a log scale (log SD Q), was moderately high with a mean of 1.18 (SEM 0.08) (normal less than 0.6). Measures of VA/Q inequality correlated poorly with spirometric findings. After salbutamol the increase in airflow rates was similar regardless of the route of administration. Intravenous salbutamol, however, caused a significant increase in heart rate, cardiac output, and oxygen consumption (VO2); in addition, both perfusion to low VA/Q areas and log SD Q increased significantly. Inhaled salbutamol caused only minor changes in heart rate, cardiac output, VO2, and VA/Q inequality. Arterial oxygen tension (PaO2) remained unchanged during salbutamol administration, irrespective of the route of administration. During 100% oxygen breathing there was a significant increase in log SD Q (from 1

  15. Acute Supramaximal Exercise Increases the Brain Oxygenation in Relation to Cognitive Workload.

    PubMed

    Bediz, Cem Seref; Oniz, Adile; Guducu, Cagdas; Ural Demirci, Enise; Ogut, Hilmi; Gunay, Erkan; Cetinkaya, Caner; Ozgoren, Murat

    2016-01-01

    Single bout of exercise can improve the performance on cognitive tasks. However, cognitive responses may be controversial due to different type, intensity, and duration of exercise. In addition, the mechanism of the effect of acute exercise on brain is still unclear. This study was aimed to investigate the effects of supramaximal exercise on cognitive tasks by means of brain oxygenation monitoring. The brain oxygenation of Prefrontal cortex (PFC) was measured on 35 healthy male volunteers via functional near infrared spectroscopy (fNIRS) system. Subjects performed 2-Back test before and after the supramaximal exercise wingate anerobic test (WAnT) lasting 30-s on cycle ergometer. The PFC oxygenation change evaluation revealed that PFC oxygenation rise during post-exercise 2-Back task was considerably higher than those in pre-exercise 2-Back task. In order to describe the relationship between oxygenation change and exercise performance, subjects were divided into two groups as high performers (HP) and low performers (LP) according to their peak power values (PP) obtained from the supramaximal test. The oxy-hemoglobin (oxy-Hb) values were compared between pre- and post-exercise conditions within subjects and also between subjects according to peak power. When performers were compared, in the HP group, the oxy-Hb values in post-exercise 2-Back test were significantly higher than those in pre-exercise 2-Back test. HP had significantly higher post-exercise oxy-Hb change (Δ) than those of LP. In addition, PP of the total group were significantly correlated with Δoxy-Hb.The key findings of the present study revealed that acute supramaximal exercise has an impact on the brain oxygenation during a cognitive task. Also, the higher the anerobic PP describes the larger the oxy-Hb response in post-exercise cognitive task. The current study also demonstrated a significant correlation between peak power (exercise load) and post-exercise hemodynamic responses (oxy-, deoxy- and

  16. Acute Supramaximal Exercise Increases the Brain Oxygenation in Relation to Cognitive Workload

    PubMed Central

    Bediz, Cem Seref; Oniz, Adile; Guducu, Cagdas; Ural Demirci, Enise; Ogut, Hilmi; Gunay, Erkan; Cetinkaya, Caner; Ozgoren, Murat

    2016-01-01

    Single bout of exercise can improve the performance on cognitive tasks. However, cognitive responses may be controversial due to different type, intensity, and duration of exercise. In addition, the mechanism of the effect of acute exercise on brain is still unclear. This study was aimed to investigate the effects of supramaximal exercise on cognitive tasks by means of brain oxygenation monitoring. The brain oxygenation of Prefrontal cortex (PFC) was measured on 35 healthy male volunteers via functional near infrared spectroscopy (fNIRS) system. Subjects performed 2-Back test before and after the supramaximal exercise wingate anerobic test (WAnT) lasting 30-s on cycle ergometer. The PFC oxygenation change evaluation revealed that PFC oxygenation rise during post-exercise 2-Back task was considerably higher than those in pre-exercise 2-Back task. In order to describe the relationship between oxygenation change and exercise performance, subjects were divided into two groups as high performers (HP) and low performers (LP) according to their peak power values (PP) obtained from the supramaximal test. The oxy-hemoglobin (oxy-Hb) values were compared between pre- and post-exercise conditions within subjects and also between subjects according to peak power. When performers were compared, in the HP group, the oxy-Hb values in post-exercise 2-Back test were significantly higher than those in pre-exercise 2-Back test. HP had significantly higher post-exercise oxy-Hb change (Δ) than those of LP. In addition, PP of the total group were significantly correlated with Δoxy-Hb.The key findings of the present study revealed that acute supramaximal exercise has an impact on the brain oxygenation during a cognitive task. Also, the higher the anerobic PP describes the larger the oxy-Hb response in post-exercise cognitive task. The current study also demonstrated a significant correlation between peak power (exercise load) and post-exercise hemodynamic responses (oxy-, deoxy- and

  17. Luminescent Nafion membranes dyed with ruthenium(II) complexes as sensing materials for dissolved oxygen

    SciTech Connect

    Garcia-Fresnadillo, D.; Orellana, G.; Marazuela, M.D.; Moreno-Bondi, M.C.

    1999-09-14

    The absorption spectroscopy, photophysics, and dioxygen quenching of [RuL{sub 3}]{sup 2+} luminescent probes, where L stands for 2,2{prime}-bipyridine, 1,10-phenanthroline, 5-octadecanamide-1,10-phenanthroline, and 4,7-diphenyl-1,10-phenanthroline (dip), electrostatically loaded onto Nafion ionomer membrane have been investigated in air and in organic solvents and water, with the aim of developing rugged materials for optical sensing of molecular oxygen. The significant differences in size and hydrophobicity of the Ru(II) dyes have been used to probe their location within the perfluorinated ionomer pore network, as well as to gain insight into the oxygen accessibility to its microcrystalline and interfacial domains. While the absorption maximums of the probes (444--458nm) remain relative unchanged, their emission wavelengths (578--622 nm) are extremely sensitive to the degree of Nafion swelling by the solvent. This feature has been characterized by measuring the density (1.19--2.04 g cm{sup {minus}3}) of the solvent-saturated ionomer and the mass and volume fractions of solvents (0.0--0.7) uptake by the original acidic Nafion and Li{sup +}-, Na{sup +}-, or K{sup +}-exchanged films. The excited-state lifetimes of the [RuL{sub 3}]{sup 2+} complexes (0.03--4.9{micro}s) reflect important variations of the microenvironment around the luminescent probes, which are rationalized in terms of their location and oxygen accessibility when loaded onto the polysulfonated material. Emission quenching rate constants of 1.7 {+-} 0.3 M{sup {minus}1}s{sup {minus}1} have been measured for the [Ru(dip){sub 3}]{sup 2+}-dyed films dipped in methanol; their oxygen sensitivity turns out to be independent of the Ru(II) loading and counterion of Nafion. Highly oxygen-sensitive luminescent membranes, suitable for continuous monitoring in organic solvents, water, or gas phase, have been prepared by immobilization of [Ru(dip){sub 3}]{sup 2+} indicator in 178-{micro}m thick Nafion, with response

  18. Room temperature alcohol sensing by oxygen vacancy controlled TiO2 nanotube array

    NASA Astrophysics Data System (ADS)

    Hazra, A.; Dutta, K.; Bhowmik, B.; Chattopadhyay, P. P.; Bhattacharyya, P.

    2014-08-01

    Oxygen vacancy (OV) controlled TiO2 nanotubes, having diameters of 50-70 nm and lengths of 200-250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH4F and ethylene glycol with selective H2O content. The structural evolution of TiO2 nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO2 nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO2 nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

  19. 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

  20. Effects of Repetitive Hyperbaric Oxygen Treatment in Patients with Acute Cerebral Infarction: A Pilot Study

    PubMed Central

    Chen, Cheng-Hsin; Chen, Shao-Yuan; Wang, Vinchi; Chen, Chao-Ching; Wang, Kaw-Chen; Chen, Chih-Hao; Liu, Yi-Chien; Lu, Kuo-Cheng; Yip, Ping-Keung; Ma, Wen-Ya; Liu, Chuan-Chieh

    2012-01-01

    The role of hyperbaric oxygen therapy (HBOT) in the treatment of acute ischemic stroke is controversial. This prospective study assessed the efficacy and safety of HBOT as adjuvant treatment on 46 acute ischemic stroke in patients who did not receive thrombolytic therapy. The HBOT group (n = 16) received conventional medical treatment with 10 sessions of adjunctive HBOT within 3–5 days after stroke onset, while the control group (n = 30) received the same treatment but without HBOT. Early (around two weeks after onset) and late (one month after onset) outcomes (National Institutes of Health Stroke Scale, NIHSS scores) and efficacy (changes of NIHSS scores) of HBOT were evaluated. The baseline clinical characteristics were similar in both groups. Both early and late outcomes of the HBOT group showed significant difference (P ≤ 0.001). In the control group, there was only significant difference in early outcome (P = 0.004). For early efficacy, there was no difference when comparing changes of NIHSS scores between the two groups (P = 0.140) but there was statistically significant difference when comparing changes of NIHSS scores at one month (P ≤ 0.001). The HBOT used in this study may be effective for patients with acute ischemic stroke and is a safe and harmless adjunctive treatment. PMID:22919348

  1. 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. PMID:26472861

  2. Human autonomic activity and its response to acute oxygen supplement after high altitude acclimatization.

    PubMed

    Bao, Xuping; Kennedy, Brian P; Hopkins, Susan R; Bogaard, Harm J; Wagner, Peter D; Ziegler, Michael G

    2002-11-29

    It is well established that after acclimatization at high altitude, many sympathetic pathways are hyperactive yet heart rate (HR) remains unchanged. In this study, we attempted to determine if this unchanged heart rate is due to compensatory mechanisms such as changes in parasympathetic activity or levels of receptors for autonomic neurotransmitters. We also examined the role played by hypoxia in these autonomic adaptations to high altitude. Three experiments were carried out on five healthy lowlanders both at sea level (SL) and after 2 weeks of acclimatization at 3800 m (Post-Ac) with: (a) placebo (control); (b) acute beta-adrenergic receptor blockade by propranolol (PRO), or (c) acute parasympathetic receptor blockade by glycopyrrolate (GLY). Compared with SL control values, post-Ac venous norepinephrine (NE) and dopamine increased by 96% (p < 0.001) and 55% (p < 0.05), but epinephrine and HR did not change. PRO resulted in a smaller decrease in HR (bpm) Post-Ac than at SL (15 +/- 6 vs. 21 +/- 6, p < 0.05), while GLY caused a greater increase in HR Post-Ac than at SL (59 +/- 8 vs. 45 +/- 6, p < 0.05). Breathing oxygen at SL concentration while at altitude did not decrease NE, or alter the effect of PRO on HR, but reduced the chronotropic effect of GLY by 14% (p < 0.05). These results suggest that after acclimatization to altitude, increased parasympathetic neurotransmitter release and decreased beta-adenoreceptor activity account for the unchanged HR despite enhanced sympathetic activity. Acute oxygen replacement rapidly counteracted the parasympathetic, but not sympathetic hyperactivity that occurs at high altitude. PMID:12492136

  3. Molybdenum chloride incorporated sol-gel materials for oxygen sensing above room temperature

    NASA Astrophysics Data System (ADS)

    Osborn, D. J., III

    Maximizing the efficiency of the combustion process requires the ability to sense oxygen levels over a broad range of concentrations with fast response times under rapidly varying conditions of pressure and temperature to maintain the correct fuel/oxygen ratio in real-time. Quenching of the luminescence from organometallic compounds by oxygen has been used to develop a number of fiber-based sensors. A major drawback of these organometallic indicators for combustion applications is that the chromophores degrade with time, have a limited operational temperature range, typically room temperature +/-25°C, and lack long-term reliability. This work investigates luminescent molybdenum clusters based on Mo6Cl12 were as replacements for organometallic indicators. A study of the high temperature stability of Mo6Cl 12 in air revealed irreversible changes in the optical absorption spectrum at T >250°C and a loss of the red luminescence characteristic of the pristine clusters. Thermal aging experiments run in air and under nitrogen point to oxidation of the clusters as the cause of the change in optical properties. X-ray powder diffraction measurements on samples annealed at 300°C under controlled conditions are consistent with oxidation of Mo6Cl 12 to form MoO3. Optical and thermal aging experiments show that K2Mo6Cl14•1H2O, the alkali metal salt of Mo6Cl12, has higher thermal stability and remains luminescent after long-term aging in air at 280°C. Methods were developed for depositing K2Mo6Cl14•1H 2O-incorporated sol--gel films on planar and optical fiber substrates by dip coating and spray coating. The mechanical properties of the films depended on the film thickness; thin films were stable, but cracks often formed in the thicker films needed for sensors. This problem was addressed using two strategies: altering the components of the sol--gel solutions used to embed the clusters and by devising a composite approach to sensing layers where a slurry of fully cured sol

  4. A green-emitting Cu complex for oxygen-sensing purpose: synthesis, characterization and photophysical features.

    PubMed

    Hui, Han; Wei, Li; Zhentao, Liu; Xiangen, Han

    2015-05-01

    In the present work, a green-emitting Cu(I) complex [Cu(BT-Et)(POP)]BF4 was synthesized and fully characterized, where BT-Et=4-(1-ethyl-1H-benzo[d]imidazol-2-yl)thiazole, POP=bis(2-(diphenylphosphanyl)phenyl) ether, respectively. An ethyl group was connected onto the diamine ligand to breach π-π attraction within solid [Cu(BT-Et)(POP)]BF4, favoring O2 molecule attack and sensitivity improvement. Its molecular identity was confirmed by single crystal analysis and theoretical calculation. [Cu(BT-Et)(POP)]BF4 emitted long-lived green emission peaking at 521nm upon photoexcitation which was vulnerable towards O2 molecule, making itself a potential oxygen sensing material. [Cu(BT-Et)(POP)]BF4 was then doped into a silica supporting matrix MCM-41. The resulting composite samples showed sensing behavior towards O2 molecule, with short response time of 10s and sensitivity of 5.56. PMID:25706596

  5. A green-emitting Cu complex for oxygen-sensing purpose: Synthesis, characterization and photophysical features

    NASA Astrophysics Data System (ADS)

    Hui, Han; Wei, Li; Zhentao, Liu; Xiangen, Han

    2015-05-01

    In the present work, a green-emitting Cu(I) complex [Cu(BT-Et)(POP)]BF4 was synthesized and fully characterized, where BT-Et = 4-(1-ethyl-1H-benzo[d]imidazol-2-yl)thiazole, POP = bis(2-(diphenylphosphanyl)phenyl) ether, respectively. An ethyl group was connected onto the diamine ligand to breach π-π attraction within solid [Cu(BT-Et)(POP)]BF4, favoring O2 molecule attack and sensitivity improvement. Its molecular identity was confirmed by single crystal analysis and theoretical calculation. [Cu(BT-Et)(POP)]BF4 emitted long-lived green emission peaking at 521 nm upon photoexcitation which was vulnerable towards O2 molecule, making itself a potential oxygen sensing material. [Cu(BT-Et)(POP)]BF4 was then doped into a silica supporting matrix MCM-41. The resulting composite samples showed sensing behavior towards O2 molecule, with short response time of 10 s and sensitivity of 5.56.

  6. A phosphorescent copper(I) complex: Synthesis, characterization, photophysical property, and oxygen-sensing behavior

    NASA Astrophysics Data System (ADS)

    Wen, Caihong; Tao, Guoquan; Xu, Xinhua; Feng, Xiaoqing; Luo, Rongcheng

    2011-09-01

    In this paper, we report the synthesis, crystal structure, photophysical properties, and electronic nature of a phosphorescent Cu(I) complex of [Cu(Phen-Np)(POP)]BF 4, where Phen-Np and POP stand for 2-(naphthalen-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline and bis(2-(diphenylphosphanyl)phenyl) ether, respectively. [Cu(Phen-Np)(POP)]BF 4 renders a yellow phosphorescence peaking at 545 nm, with a long excited state lifetime of 4.69 μs. Density functional calculation reveals that the emission comes from a triplet metal-to-ligand-charge-transfer excited state. We electrospun composite nanofibers of [Cu(Phen-Np)(POP)]BF 4 and polystyrene (PS), hoping to explore the possibility of using the composite nanofibers as an oxygen sensing material. The finally obtained samples with average diameter of ˜300 nm exhibit a maximum sensitivity of 7.2 towards molecular oxygen with short response time of 7 s due to the large surface-area-to-volume ratio of nanofibrous membranes. No photobleaching is detected in these samples.

  7. Synthesis, characterization and theoretical analysis on a oxygen-sensing phosphorescent copper(I) complex

    NASA Astrophysics Data System (ADS)

    Li, Zheng

    2011-10-01

    In this paper, we report the synthesis, crystal structure, photophysical properties, and electronic nature of a phosphorescent Cu(I) complex of [Cu(Phen-Ph)(PPh 3) 2]BF 4, where Phen-Ph and PPh 3 stand for 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline and triphenylphosphine, respectively. [Cu(Phen-Ph)(PPh 3) 2]BF 4 renders a yellow phosphorescence peaking at 553 nm, with a long excited state lifetime of 13.2 μs under N 2 atmosphere. Density functional calculation reveals that the emission comes from a triplet metal-to-ligand-charge-transfer excited state. We electrospun composite nanofibers of [Cu(Phen-Ph)(PPh 3) 2]BF 4 and polystyrene (PS), hoping to explore the possibility of using the composite nanofibers as an oxygen sensing material. The finally obtained samples with average diameter of ˜400 nm exhibit a maximum sensitivity of 6.52 towards molecular oxygen with short response time of 15 s due to the large surface-area-to-volume ratio of nanofibrous membranes. No photobleaching is detected in these samples.

  8. Early non-destructive biofouling detection and spatial distribution: Application of oxygen sensing optodes.

    PubMed

    Farhat, N M; Staal, M; Siddiqui, A; Borisov, S M; Bucs, Sz S; Vrouwenvelder, J S

    2015-10-15

    Biofouling is a serious problem in reverse osmosis/nanofiltration (RO/NF) applications, reducing membrane performance. Early detection of biofouling plays an essential role in an adequate anti-biofouling strategy. Presently, fouling of membrane filtration systems is mainly determined by measuring changes in pressure drop, which is not exclusively linked to biofouling. Non-destructive imaging of oxygen concentrations (i) is specific for biological activity of biofilms and (ii) may enable earlier detection of biofilm accumulation than pressure drop. The objective of this study was to test whether transparent luminescent planar O2 optodes, in combination with a simple imaging system, can be used for early non-destructive biofouling detection. This biofouling detection is done by mapping the two-dimensional distribution of O2 concentrations and O2 decrease rates inside a membrane fouling simulator (MFS). Results show that at an early stage, biofouling development was detected by the oxygen sensing optodes while no significant increase in pressure drop was yet observed. Additionally, optodes could detect spatial heterogeneities in biofouling distribution at a micro scale. Biofilm development started mainly at the feed spacer crossings. The spatial and quantitative information on biological activity will lead to better understanding of the biofouling processes, contributing to the development of more effective biofouling control strategies. PMID:26117369

  9. Efficiency of hyperbaric oxygen therapy in experimental acute acoustic trauma from firearms.

    PubMed

    Kuokkanen, J; Aarnisalo, A A; Ylikoski, J

    2000-01-01

    In acute acoustic trauma (AAT), excessive noise exposure causes rupture of cell membranes and decreased cochlear blood flow. This leads to decreased oxygen tension in inner ear fluids and reduction of a variety of different oxygen-dependent cellular activities. Hyperbaric oxygen treatment (HBO) may help the cells suffering from hypoxia to survive. We exposed male Wistar rats to 60 impulses of 162-dB SPL from a 7.62-mm assault rifle equipped with a blank adaptor. After the exposure, 15 animals were given HBO treatment for 90 min daily for 10 consecutive days at 0.25 MPa. After a survival time of 4 weeks, auditory brainstem responses were measured and the left cochleae processed for light microscopy. The impulse noise caused permanent damage to the cochlea of all animals, with the most severe lesions in the lower middle coil, where a significantly smaller number of hair cells was missing in the HBO-treated group. The morphological damage was also reflected in function, as measured by auditory brainstem responses, which showed the greatest threshold shifts at 6.0, 8.0 and 10.0 kHz. PMID:10909001

  10. Oxygenation, EMG and position sense during computer mouse work. Impact of active versus passive pauses.

    PubMed

    Crenshaw, A G; Djupsjöbacka, M; Svedmark, A

    2006-05-01

    We investigated the effects of active versus passive pauses implemented during computer mouse work on muscle oxygenation and EMG of the forearm extensor carpi radialis muscle, and on wrist position sense. Fifteen healthy female subjects (age: 19-24 years) performed a 60-min mouse-operated computer task, divided into three 20 min periods, on two occasions separated by 3-6 days. On one occasion a passive pause (subjects resting) was implemented at the end of each 20-min period, and on another occasion an active pause (subjects performed a number of high intensity extensions of the forearm) was implemented. Also at the end of each 20-min period, test contractions were conducted and subjective ratings of fatigue and stress were obtained. Another parameter of interest was total haemoglobin calculated as the summation of oxy-and deoxy-haemoglobin, since it reflects blood volume changes. The most interesting findings were an overall increasing trend in total haemoglobin throughout the mouse work (P<0.001), and that this trend was greater for the active pause as compared to the passive pause (P<0.01). These data were accompanied by an overall increase in oxygen saturation (P<0.001), with a tendency, albeit not significant, toward a higher increase for the active pause (P=0.13). EMG amplitude and median frequency tended to decrease (P=0.08 and 0.05, respectively) during the mouse work but was not different between pause types. Borg ratings of forearm fatigue showed an overall increase during the activity (P<0.001), but the perceptions of stress did not change. Position sense did not change due to the mouse work for either pause type. While increasing trends were found for both pause types, the present study lends support to the hypothesis of an enhancement in oxygenation and blood volume for computer mouse work implemented with active pauses. However, a presumption of an association between this enhancement and attenuated fatigue during the mouse work was not supported

  11. Interdisciplinary Peripartum Management of Acute Respiratory Distress Syndrome with Extracorporeal Membrane Oxygenation – a Case Report and Literature Review

    PubMed Central

    Weyrich, J.; Bogdanski, R.; Ortiz, J. U.; Kuschel, B.; Schneider, K. T. M.; Lobmaier, S. M.

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) is increasingly used for the management of acute severe cardiac and respiratory failure. One of the indications is acute respiratory distress syndrome (ARDS) for which, in some severe cases, ECMO represents the only possibility to save lives. We report on the successful long-term use of ECMO in a postpartum patient with recurrent pulmonary decompensation after peripartum uterine rupture with extensive blood loss. PMID:27065489

  12. Click-assembled, oxygen sensing nanoconjugates for depth-resolved, near-infrared imaging in a 3D cancer model

    PubMed Central

    Nichols, Alexander J.; Roussakis, Emmanuel; Klein, Oliver J.

    2014-01-01

    Hypoxia is an important factor that contributes to the development of drug-resistant cancer, yet few non-perturbative tools exist for studying oxygen in tissue. While progress has been made in the development of chemical probes for optical oxygen mapping, penetration into poorly perfused or avascular tumor regions remains problematic. Here we report a Click-Assembled Oxygen Sensing (CAOS) nanoconjugate and demonstrate its properties in an in vitro 3D spheroid cancer model. Our synthesis relies on sequential click-based ligation of poly(amidoamine)-like subunits for rapid assembly. Using near-infrared confocal phosphorescence microscopy, we demonstrate the ability of CAOS nanoconjugates to penetrate hundreds of microns into spheroids within hours and show their sensitivity to oxygen changes throughout the nodule. This proof-of-concept study demonstrates a modular approach that is readily extensible to a wide variety of oxygen and cellular sensors for depth-resolved imaging in tissue and tissue models. PMID:24590700

  13. The role of oxygen in hydrogen sensing by a platinum-gate silicon carbide gas sensor: An ultrahigh vacuum study

    NASA Astrophysics Data System (ADS)

    Kahng, Yung Ho; Lu, Wei; Tobin, R. G.; Loloee, Reza; Ghosh, Ruby N.

    2009-03-01

    We report several experiments under ultrahigh vacuum conditions that elucidate the role of oxygen in the functioning of silicon carbide field-effect gas sensors with nonporous platinum gates. The devices studied are shown to be sensitive both to hydrogen and to propene. All of the results are consistent with oxygen acting through its surface reactions with hydrogen. Three specific aspects are highlighted: the need, under some conditions, for oxygen to reset the device to a fully hydrogen-depleted state; competition between hydrogen oxidation and hydrogen diffusion to metal/oxide interface sites, leading to steplike behavior as a function of the oxygen:hydrogen ratio (λ-sensing); and the removal of sulfur contamination by oxygen.

  14. 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. PMID:27118044

  15. 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

    2017-01-01

    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, 0.05mL) 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. PMID:27450122

  16. Luminescent sensing of dissolved oxygen based on Ru(II) complex embedded in sol-gel matrix

    NASA Astrophysics Data System (ADS)

    Bi, Yubing; Tao, Wei; Hu, Yanli; Mao, Yimei; Zhao, Hui

    2015-11-01

    In biological cells and tissues environment, real-time monitoring and controlling dissolved oxygen (DO) provides critical information for studying cellular metabolism process, health status and pathological features. This paper developed an optical DO sensor based on fluorescence quenching principle, prepared tris(4,7-diphenyl-1,10- phenanthroline)ruthenium(II) dichloride complex sol-gel sensing film, and studied its sensing performance. The principle of this sensor is that dissolved oxygen has quenching effect towards the fluorescence emitted by ruthenium complex. So the fluorescence intensity is reduced due to the existence of DO. The measurement limit of DO was 10- 100%, the response time was 20s, and the resolution was 0.02. Compared to traditional dissolved oxygen electrode probe, this luminescent fiber had many advantages, such as smaller size, shorter response time and higher stability.

  17. Combined administration of hyperbaric oxygen and hydroxocobalamin improves cerebral metabolism after acute cyanide poisoning in rats.

    PubMed

    Hansen, M B; Olsen, N V; Hyldegaard, O

    2013-11-01

    Hyperbaric oxygen therapy (HBOT) or intravenous hydroxocobalamin (OHCob) both abolish cyanide (CN)-induced surges in interstitial brain lactate and glucose concentrations. HBOT has been shown to induce a delayed increase in whole blood CN concentrations, whereas OHCob may act as an intravascular CN scavenger. Additionally, HBOT may prevent respiratory distress and restore blood pressure during CN intoxication, an effect not seen with OHCob administration. In this report, we evaluated the combined effects of HBOT and OHCob on interstitial lactate, glucose, and glycerol concentrations as well as lactate-to-pyruvate ratio in rat brain by means of microdialysis during acute CN poisoning. Anesthetized rats were allocated to three groups: 1) vehicle (1.2 ml isotonic NaCl intra-arterially); 2) potassium CN (5.4 mg/kg intra-arterially); 3) potassium CN, OHCob (100 mg/kg intra-arterially) and subsequent HBOT (284 kPa in 90 min). OHCob and HBOT significantly attenuated the acute surges in interstitial cerebral lactate, glucose, and glycerol concentrations compared with the intoxicated rats given no treatment. Furthermore, the combined treatment resulted in consistent low lactate, glucose, and glycerol concentrations, as well as in low lactate-to-pyruvate ratios compared with CN intoxicated controls. In rats receiving OHCob and HBOT, respiration improved and cyanosis disappeared, with subsequent stabilization of mean arterial blood pressure. The present findings indicate that a combined administration of OHCob and HBOT has a beneficial and persistent effect on the cerebral metabolism during CN intoxication. PMID:23970528

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

    SciTech Connect

    Sheard, Michael A.; Ghent, Matthew V.; Cabral, Daniel J.; Lee, Joanne C.; Khankaldyyan, Vazgen; Ji, Lingyun; Wu, Samuel Q.; Kang, Min H.; and others

    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. - 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.

  19. Acute exercise increases oxygenated and deoxygenated hemoglobin in the prefrontal cortex.

    PubMed

    Giles, Grace E; Brunyé, Tad T; Eddy, Marianna D; Mahoney, Caroline R; Gagnon, Stephanie A; Taylor, Holly A; Kanarek, Robin B

    2014-11-12

    Both acute and chronic exercise is consistently associated with a number of benefits to physical and mental health, including cardiovascular function, body weight, mood, and cognition. Near-infrared spectroscopy is an ideal method to measure changes in oxygenated and deoxygenated hemoglobin (O2Hb and dHb) levels in the prefrontal cortex (PFC) during exercise, to better understand the locus of such changes in affective and cognitive processes. The present study tracked time-dependent changes in O2Hb and dHb levels in the PFC as a function of parametrically manipulated target exercise intensity. Near-infrared spectroscopy was conducted as regular exercisers completed a 30-min bout of exercise with one of three target intensities: 52% (low condition), 68% (moderate condition), or 84% (high condition) of age-adjusted maximum heart rate. Heart rate data confirmed that the participants reached their goal intensities immediately, after 10 min, or after 20 min, respectively. Data showed that O2Hb and dHb levels in the PFC increased as a function of both exercise load and duration. An 84%>68%>52% difference was evident after 18 min of cycling for O2Hb and after 23 min of cycling for dHb. The present results add to the growing body of literature showing that at submaximal levels, increasing exercise intensities reliably promote prefrontal cerebral oxygenation. PMID:25275640

  20. Low Doses of Oxygen Ion Irradiation Cause Acute Damage to Hematopoietic Cells in Mice.

    PubMed

    Chang, Jianhui; Luo, Yi; Wang, Yingying; Pathak, Rupak; Sridharan, Vijayalakshmi; Jones, Tamako; Mao, Xiao Wen; Nelson, Gregory; Boerma, Marjan; Hauer-Jensen, Martin; Zhou, Daohong; Shao, Lijian

    2016-01-01

    One of the major health risks to astronauts is radiation on long-duration space missions. Space radiation from sun and galactic cosmic rays consists primarily of 85% protons, 14% helium nuclei and 1% high-energy high-charge (HZE) particles, such as oxygen (16O), carbon, silicon, and iron ions. HZE particles exhibit dense linear tracks of ionization associated with clustered DNA damage and often high relative biological effectiveness (RBE). Therefore, new knowledge of risks from HZE particle exposures must be obtained. In the present study, we investigated the acute effects of low doses of 16O irradiation on the hematopoietic system. Specifically, we exposed C57BL/6J mice to 0.1, 0.25 and 1.0 Gy whole body 16O (600 MeV/n) irradiation and examined the effects on peripheral blood (PB) cells, and bone marrow (BM) hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) at two weeks after the exposure. The results showed that the numbers of white blood cells, lymphocytes, monocytes, neutrophils and platelets were significantly decreased in PB after exposure to 1.0 Gy, but not to 0.1 or 0.25 Gy. However, both the frequency and number of HPCs and HSCs were reduced in a radiation dose-dependent manner in comparison to un-irradiated controls. Furthermore, HPCs and HSCs from irradiated mice exhibited a significant reduction in clonogenic function determined by the colony-forming and cobblestone area-forming cell assays. These acute adverse effects of 16O irradiation on HSCs coincided with an increased production of reactive oxygen species (ROS), enhanced cell cycle entry of quiescent HSCs, and increased DNA damage. However, none of the 16O exposures induced apoptosis in HSCs. These data suggest that exposure to low doses of 16O irradiation induces acute BM injury in a dose-dependent manner primarily via increasing ROS production, cell cycling, and DNA damage in HSCs. This finding may aid in developing novel strategies in the protection of the hematopoietic

  1. Low Doses of Oxygen Ion Irradiation Cause Acute Damage to Hematopoietic Cells in Mice

    PubMed Central

    Wang, Yingying; Pathak, Rupak; Sridharan, Vijayalakshmi; Jones, Tamako; Mao, Xiao Wen; Nelson, Gregory; Boerma, Marjan; Hauer-Jensen, Martin; Zhou, Daohong; Shao, Lijian

    2016-01-01

    One of the major health risks to astronauts is radiation on long-duration space missions. Space radiation from sun and galactic cosmic rays consists primarily of 85% protons, 14% helium nuclei and 1% high-energy high-charge (HZE) particles, such as oxygen (16O), carbon, silicon, and iron ions. HZE particles exhibit dense linear tracks of ionization associated with clustered DNA damage and often high relative biological effectiveness (RBE). Therefore, new knowledge of risks from HZE particle exposures must be obtained. In the present study, we investigated the acute effects of low doses of 16O irradiation on the hematopoietic system. Specifically, we exposed C57BL/6J mice to 0.1, 0.25 and 1.0 Gy whole body 16O (600 MeV/n) irradiation and examined the effects on peripheral blood (PB) cells, and bone marrow (BM) hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) at two weeks after the exposure. The results showed that the numbers of white blood cells, lymphocytes, monocytes, neutrophils and platelets were significantly decreased in PB after exposure to 1.0 Gy, but not to 0.1 or 0.25 Gy. However, both the frequency and number of HPCs and HSCs were reduced in a radiation dose-dependent manner in comparison to un-irradiated controls. Furthermore, HPCs and HSCs from irradiated mice exhibited a significant reduction in clonogenic function determined by the colony-forming and cobblestone area-forming cell assays. These acute adverse effects of 16O irradiation on HSCs coincided with an increased production of reactive oxygen species (ROS), enhanced cell cycle entry of quiescent HSCs, and increased DNA damage. However, none of the 16O exposures induced apoptosis in HSCs. These data suggest that exposure to low doses of 16O irradiation induces acute BM injury in a dose-dependent manner primarily via increasing ROS production, cell cycling, and DNA damage in HSCs. This finding may aid in developing novel strategies in the protection of the hematopoietic

  2. Roles of Proton-Sensing Receptors in the Transition from Acute to Chronic Pain.

    PubMed

    Sun, W H; Chen, C C

    2016-02-01

    Chronic pain, when not effectively treated, is a leading health and socioeconomic problem and has a harmful effect on all aspects of health-related quality of life. Therefore, understanding the molecular mechanism of how pain transitions from the acute to chronic phase is essential for developing effective novel analgesics. Accumulated evidence has shown that the transition from acute to chronic pain is determined by a cellular signaling switch called hyperalgesic priming, which occurs in primary nociceptive afferents. The hyperalgesic priming is triggered by inflammatory mediators and is involved in a signal switch from protein kinase A (PKA) to protein kinase Cε (PKCε) located in both isolectin B4 (IB4)-positive (nonpeptidergic) and IB4-negative (peptidergic) nociceptors. Acidosis may be the decisive factor regulating the PKA-to-PKCε signal switch in a proton-sensing G-protein-coupled receptor-dependent manner. Protons can also induce the hyperalgesic priming in IB4-negative muscle nociceptors in a PKCε-independent manner. Acid-sensing ion channel 3 (ASIC3) and transient receptor potential/vanilloid receptor subtype 1 (TRPV1) are 2 major acid sensors involved in the proton-induced hyperalgesic priming. The proton-induced hyperalgesic priming in muscle afferents can be prevented by a substance P-mediated signaling pathway. In this review, we summarize the factors that modulate hyperalgesic priming in both IB4-positive and IB4-negative nociceptors and discuss the role of acid signaling in inflammatory and noninflammatory pain as well as orofacial muscle pain. PMID:26597969

  3. Cellular Oxygen Sensing: Crystal Structure of Hypoxia-Inducible Factor Prolyl Hydroxylase (PHD2)

    SciTech Connect

    McDonough,M.; Li, V.; Flashman, E.; Chowdhury, R.; Mohr, C.; Lienard, B.; Zondlo, J.; Oldham, N.; Clifton, I.; et al.

    2006-01-01

    Cellular and physiological responses to changes in dioxygen levels in metazoans are mediated via the posttranslational oxidation of hypoxia-inducible transcription factor (HIF). Hydroxylation of conserved prolyl residues in the HIF-{alpha} subunit, catalyzed by HIF prolyl-hydroxylases (PHDs), signals for its proteasomal degradation. The requirement of the PHDs for dioxygen links changes in dioxygen levels with the transcriptional regulation of the gene array that enables the cellular response to chronic hypoxia; the PHDs thus act as an oxygen-sensing component of the HIF system, and their inhibition mimics the hypoxic response. We describe crystal structures of the catalytic domain of human PHD2, an important prolyl-4-hydroxylase in the human hypoxic response in normal cells, in complex with Fe(II) and an inhibitor to 1.7 Angstroms resolution. PHD2 crystallizes as a homotrimer and contains a double-stranded {beta}-helix core fold common to the Fe(II) and 2-oxoglutarate-dependant dioxygenase family, the residues of which are well conserved in the three human PHD enzymes (PHD 1-3). The structure provides insights into the hypoxic response, helps to rationalize a clinically observed mutation leading to familial erythrocytosis, and will aid in the design of PHD selective inhibitors for the treatment of anemia and ischemic disease.

  4. Room temperature alcohol sensing by oxygen vacancy controlled TiO{sub 2} nanotube array

    SciTech Connect

    Hazra, A.; Dutta, K.; Bhowmik, B.; Bhattacharyya, P.; Chattopadhyay, P. P.

    2014-08-25

    Oxygen vacancy (OV) controlled TiO{sub 2} nanotubes, having diameters of 50–70 nm and lengths of 200–250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH{sub 4}F and ethylene glycol with selective H{sub 2}O content. The structural evolution of TiO{sub 2} nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO{sub 2} nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO{sub 2} nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

  5. Oxygen Sensing by T Cells Establishes an Immunologically Tolerant Metastatic Niche.

    PubMed

    Clever, David; Roychoudhuri, Rahul; Constantinides, Michael G; Askenase, Michael H; Sukumar, Madhusudhanan; Klebanoff, Christopher A; Eil, Robert L; Hickman, Heather D; Yu, Zhiya; Pan, Jenny H; Palmer, Douglas C; Phan, Anthony T; Goulding, John; Gattinoni, Luca; Goldrath, Ananda W; Belkaid, Yasmine; Restifo, Nicholas P

    2016-08-25

    Cancer cells must evade immune responses at distant sites to establish metastases. The lung is a frequent site for metastasis. We hypothesized that lung-specific immunoregulatory mechanisms create an immunologically permissive environment for tumor colonization. We found that T-cell-intrinsic expression of the oxygen-sensing prolyl-hydroxylase (PHD) proteins is required to maintain local tolerance against innocuous antigens in the lung but powerfully licenses colonization by circulating tumor cells. PHD proteins limit pulmonary type helper (Th)-1 responses, promote CD4(+)-regulatory T (Treg) cell induction, and restrain CD8(+) T cell effector function. Tumor colonization is accompanied by PHD-protein-dependent induction of pulmonary Treg cells and suppression of IFN-γ-dependent tumor clearance. T-cell-intrinsic deletion or pharmacological inhibition of PHD proteins limits tumor colonization of the lung and improves the efficacy of adoptive cell transfer immunotherapy. Collectively, PHD proteins function in T cells to coordinate distinct immunoregulatory programs within the lung that are permissive to cancer metastasis. PAPERCLIP. PMID:27565342

  6. Quantum Dots in an Amphiphilic Polyethyleneimine Derivative Platform for Cellular Labeling, Targeting, Gene Delivery, and Ratiometric Oxygen Sensing.

    PubMed

    Park, Joonhyuck; Lee, Junhwa; Kwag, Jungheon; Baek, Yeonggyeong; Kim, Bumju; Yoon, Calvin Jinse; Bok, Seoyeon; Cho, So-Hye; Kim, Ki Hean; Ahn, G-One; Kim, Sungjee

    2015-06-23

    Amphiphilic polyethyleneimine derivatives (amPEIs) were synthesized and used to encapsulate dozens of quantum dots (QDs). The QD-amPEI composite was ∼100 nm in hydrodynamic diameter and had the slightly positive outer surface that suited well for cellular internalization. The QD-amPEI showed very efficient QD cellular labeling with the labeled cell fluorescence intensity more than 10 times higher than conventional techniques such as Lipofectamine-assisted QD delivery. QD-amPEI was optimal for maximal intracellular QD delivery by the large QD payload and the rapid endocytosis kinetics. QD-amPEI platform technology was demonstrated for gene delivery, cell-specific labeling, and ratiometric oxygen sensing. Our QD-amPEI platform has two partitions: positive outer surface and hydrophobic inside pocket. The outer positive surface was further exploited for gene delivery and targeting. Co-delivery of QDs and GFP silencing RNAs was successfully demonstrated by assembling siRNAs to the outer surfaces, which showed the transfection efficiency an order of magnitude higher than conventional gene transfections. Hyaluronic acids were tethered onto the QD-amPEI for cell-specific targeted labeling which showed the specific-to-nonspecific signal ratio over 100. The inside hydrophobic compartment was further applied for cohosting oxygen sensing phosphorescence Ru dyes along with QDs. The QD-Ru-amPEI oxygen probe showed accurate and reversible oxygen sensing capability by the ratiometric photoluminescence signals, which was successfully applied to cellular and spheroid models. PMID:26057729

  7. Oxygen-sensing mechanisms and the regulation of redox-responsive transcription factors in development and pathophysiology

    PubMed Central

    Haddad, John J

    2002-01-01

    How do organisms sense the amount of oxygen in the environment and respond appropriately when the level of oxygen decreases? Oxygen sensing and the molecular stratagems underlying the process have been the focus of an endless number of investigations trying to find an answer to the question: "What is the identity of the oxygen sensor?" Dynamic changes in pO2 constitute a potential signaling mechanism for the regulation of the expression and activation of reduction-oxidation (redox)-sensitive and oxygen-responsive transcription factors, apoptosis-signaling molecules and inflammatory cytokines. The transition from placental to lung-based respiration causes a relatively hyperoxic shift or oxidative stress, which the perinatal, developing lung experiences during birth. This variation in ΔpO2, in particular, differentially regulates the compartmentalization and functioning of the transcription factors hypoxia-inducible factor-1α (HIF-1α) and nuclear factor-κB (NF-κB). In addition, oxygen-evoked regulation of HIF-1α and NF-κB is closely coupled with the intracellular redox state, such that modulating redox equilibrium affects their responsiveness at the molecular level (expression/transactivation). The differential regulation of HIF-1α and NF-κB in vitro is paralleled by oxygen-sensitive and redox-dependent pathways governing the regulation of these factors during the transition from placental to lung-based respiration ex utero. The birth transition period in vivo and ex utero also regulates apoptosis signaling pathways in a redox-dependent manner, consistent with NF-κB being transcriptionally regulated in order to play an anti-apoptotic function. An association is established between oxidative stress conditions and the augmentation of an inflammatory state in pathophysiology, regulated by the oxygen- and redox-sensitive pleiotropic cytokines. PMID:12537605

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

    ClinicalTrials.gov

    2016-01-25

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

  9. Oxygen-Sensing Reporter Strain of Pseudomonas fluorescens for Monitoring the Distribution of Low-Oxygen Habitats in Soil

    PubMed Central

    Højberg, Ole; Schnider, Ursula; Winteler, Harald V.; Sørensen, Jan; Haas, Dieter

    1999-01-01

    The root-colonizing bacterium Pseudomonas fluorescens CHA0 was used to construct an oxygen-responsive biosensor. An anaerobically inducible promoter of Pseudomonas aeruginosa, which depends on the FNR (fumarate and nitrate reductase regulation)-like transcriptional regulator ANR (anaerobic regulation of arginine deiminase and nitrate reductase pathways), was fused to the structural lacZ gene of Escherichia coli. By inserting the reporter fusion into the chromosomal attTn7 site of P. fluorescens CHA0 by using a mini-Tn7 transposon, the reporter strain, CHA900, was obtained. Grown in glutamate-yeast extract medium in an oxystat at defined oxygen levels, the biosensor CHA900 responded to a decrease in oxygen concentration from 210 × 102 Pa to 2 × 102 Pa of O2 by a nearly 100-fold increase in β-galactosidase activity. Half-maximal induction of the reporter occurred at about 5 × 102 Pa. This dose response closely resembles that found for E. coli promoters which are activated by the FNR protein. In a carbon-free buffer or in bulk soil, the biosensor CHA900 still responded to a decrease in oxygen concentration, although here induction was about 10 times lower and the low oxygen response was gradually lost within 3 days. Introduced into a barley-soil microcosm, the biosensor could report decreasing oxygen concentrations in the rhizosphere for a 6-day period. When the water content in the microcosm was raised from 60% to 85% of field capacity, expression of the reporter gene was elevated about twofold above a basal level after 2 days of incubation, suggesting that a water content of 85% caused mild anoxia. Increased compaction of the soil was shown to have a faster and more dramatic effect on the expression of the oxygen reporter than soil water content alone, indicating that factors other than the water-filled pore space influenced the oxygen status of the soil. These experiments illustrate the utility of the biosensor for detecting low oxygen concentrations in the

  10. UHV Studies of Oxygen's Role in Hydrogen Sensing with a Platinum-Gate Silicon Carbide Field-Effect Device

    NASA Astrophysics Data System (ADS)

    Tobin, Roger; Kahng, Yung Ho; Loloee, Reza; Ghosh, Ruby

    2008-03-01

    Silicon carbide-based field-effect devices with catalytic metal gates are promising as robust high-temperature gas sensors in harsh environments. We report ultrahigh vacuum studies of the gate surface chemistry of prototype Pt-SiO2-SiC sensors. Oxygen plays a crucial role in the device's hydrogen-sensing behavior. Adsorbed oxygen can remove hydrogen by reacting to form water, which rapidly desorbs. In an oxygen-rich environment this reaction competes with the diffusion of adsorbed hydrogen to the interface bonding sites that give rise to the sensor signal. This competition reduces the sensor signal by decreasing the occupation of interface sites. The same reaction, however, is essential to the reversibility of the sensor, as oxygen is needed to fully deplete the sensor of hydrogen. Exposure to H2S suppresses the sensor's response to alternating hydrogen and oxygen pulses, apparently by interfering with oxygen adsorption. Continued oxygen exposure, however, restores functionality by effectively removing the sulfur.

  11. A power law fit to oxygen absorption at 60 GHz and its application to remote sensing of atmospheric temperature

    NASA Technical Reports Server (NTRS)

    Poon, R. K. L.

    1980-01-01

    The paper presents an empirical study of the oxygen spectrum near 60 GHz with reference to its applicability to the remote sensing of the tropospheric and lower stratospheric temperature. It is demonstrated that the absorption coefficient of oxygen at 60 GHz can be fitted to the power law form with a relative rms error of about 8%. The power law form, when used in conjunction with the weighting function, permits the definition of some basic quantities in the passive remote sensing of the atmospheric temperature. It is shown how the power law form has been utilized in processing data from the Nimbus 5 microwave spectrometer experiment. The algorithm presented can be applied to spectrometer experiments at infrared frequencies.

  12. Effects of nebulized terbutaline on oxygen saturation in acute asthmatic children.

    PubMed

    Lin, Y Z; Hsieh, K H; Shih, T Y; Chen, W; Wu, K W

    1994-01-01

    To evaluate the paradoxical effect of oxygen desaturation following beta-2 bronchodilator nebulization treatment in acute asthmatic children, a total of 47 patients, aged between 1.8 and 14 years, 27 males and 20 females, were studied. Twenty ml of nebulized normal saline (NS), followed by 10 mg (4 ml) of terbutaline sulphate solution (TSS) in 20 ml NS, were delivered by an ultrasonic nebulizer in 10 min to each patient through a connecting air tube placed in front of the nose and mouth. Oxygen saturation (SaO2) and pulse rate were monitored, using a pulse oximeter, before study and every two minutes until the end of the study. The clinical severity score and peak expiratory flow rate (PEFR) were checked before the study, at the end of inhalation of NS, and at the end of inhalation of TSS. SaO2 was increased both after nebulized NS and TSS when compared with the pre-study data (p < 0.05 and p < 0.0001, respectively). Twenty two cases (47%) during NS and 12 cases (25%) during TSS nebulization had SaO2 below the pre-study level. The mean decrease of SaO2 for the former was 1.62 +/- 0.95% (range: 1.00% to 4.26%), and 1.64 +/- 0.83% (range: 1.02% to 3.13%) for the latter (p > 0.9). No SaO2 decrease after nebulized TSS was observed in any of the seven severe asthmatic children with a prestudy SaO2 < or = 90%. The clinical severity score and PEFR were also significantly improved both after nebulized NS and TSS (p < 0.0001 and p < 0.001, respectively for NS, and both p < 0.0001 for TSS).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7942023

  13. F-box and Leucine-rich Repeat Protein 5 (FBXL5): sensing intracellular iron and oxygen

    PubMed Central

    Ruiz, Julio C.; Bruick, Richard K.

    2014-01-01

    Though essential for many vital biological processes, excess iron results in the formation of damaging reactive oxygen species (ROS). Therefore, iron metabolism must be tightly regulated. F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, regulates cellular and systemic iron homeostasis by facilitating iron regulatory protein 2 (IRP2) degradation. FBXL5 possesses an N-terminal hemerythrin (Hr)-like domain that mediates its own differential stability by switching between two different conformations to communicate cellular iron availability. In addition, the FBXL5-Hr domain also senses O2 availability, albeit by a distinct mechanism. Mice lacking FBXL5 fail to sense intracellular iron levels and die in utero due to iron overload and exposure to damaging levels of oxidative stress. By closely monitoring intracellular levels of iron and oxygen, FBLX5 prevents the formation of conditions that favor ROS formation. These findings suggest that FBXL5 is essential for the maintenance of iron homeostasis and is a key sensor of bioavailable iron. Here, we describe the iron and oxygen sensing mechanisms of the FBXL5 Hr-like domain and its role in mediating ROS biology. PMID:24508277

  14. F-box and leucine-rich repeat protein 5 (FBXL5): sensing intracellular iron and oxygen.

    PubMed

    Ruiz, Julio C; Bruick, Richard K

    2014-04-01

    Though essential for many vital biological processes, excess iron results in the formation of damaging reactive oxygen species (ROS). Therefore, iron metabolism must be tightly regulated. F-box and leucine-rich repeat protein 5 (FBXL5), an E3 ubiquitin ligase subunit, regulates cellular and systemic iron homeostasis by facilitating iron regulatory protein 2 (IRP2) degradation. FBXL5 possesses an N-terminal hemerythrin (Hr)-like domain that mediates its own differential stability by switching between two different conformations to communicate cellular iron availability. In addition, the FBXL5-Hr domain also senses O2 availability, albeit by a distinct mechanism. Mice lacking FBXL5 fail to sense intracellular iron levels and die in utero due to iron overload and exposure to damaging levels of oxidative stress. By closely monitoring intracellular levels of iron and oxygen, FBLX5 prevents the formation of conditions that favor ROS formation. These findings suggest that FBXL5 is essential for the maintenance of iron homeostasis and is a key sensor of bioavailable iron. Here, we describe the iron and oxygen sensing mechanisms of the FBXL5 Hr-like domain and its role in mediating ROS biology. PMID:24508277

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

    PubMed Central

    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. PMID:27006941

  16. 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. PMID:23220016

  17. Exceptional Oxygen Sensing Properties of New Blue Light-Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

    PubMed Central

    Borisov, Sergey M.; Fischer, Roland; Saf, Robert; Klimant, Ingo

    2016-01-01

    New europium(III) and gadolinium(III) complexes bearing 8-hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state-of-the-art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow-band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g. in multi-analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state-of-the-art oxygen indicators particularly for such applications as e.g. food packaging. PMID:27158252

  18. DNMT3a epigenetic program regulates the HIF-2α oxygen-sensing pathway and the cellular response to hypoxia

    PubMed Central

    Lachance, Gabriel; Uniacke, James; Audas, Timothy E.; Holterman, Chet E.; Franovic, Aleksandra; Payette, Josianne; Lee, Stephen

    2014-01-01

    Epigenetic regulation of gene expression by DNA methylation plays a central role in the maintenance of cellular homeostasis. Here we present evidence implicating the DNA methylation program in the regulation of hypoxia-inducible factor (HIF) oxygen-sensing machinery and hypoxic cell metabolism. We show that DNA methyltransferase 3a (DNMT3a) methylates and silences the HIF-2α gene (EPAS1) in differentiated cells. Epigenetic silencing of EPAS1 prevents activation of the HIF-2α gene program associated with hypoxic cell growth, thereby limiting the proliferative capacity of adult cells under low oxygen tension. Naturally occurring defects in DNMT3a, observed in primary tumors and malignant cells, cause the unscheduled activation of EPAS1 in early dysplastic foci. This enables incipient cancer cells to exploit the HIF-2α pathway in the hypoxic tumor microenvironment necessary for the formation of cellular masses larger than the oxygen diffusion limit. Reintroduction of DNMT3a in DNMT3a-defective cells restores EPAS1 epigenetic silencing, prevents hypoxic cell growth, and suppresses tumorigenesis. These data support a tumor-suppressive role for DNMT3a as an epigenetic regulator of the HIF-2α oxygen-sensing pathway and the cellular response to hypoxia. PMID:24817692

  19. Silicon-on-glass pore network micromodels with oxygen-sensing fluorophore films for chemical imaging and defined spatial structure.

    PubMed

    Grate, Jay W; Kelly, Ryan T; Suter, Jonathan; Anheier, Norm C

    2012-11-21

    Pore network microfluidic models were fabricated by a silicon-on-glass technique that provides the precision advantage of dry etched silicon while creating a structure that is transparent across all microfluidic channels and pores, and can be imaged from either side. A silicon layer is bonded to an underlying borosilicate glass substrate and thinned to the desired height of the microfluidic channels and pores. The silicon is then patterned and through-etched by deep reactive ion etching (DRIE), with the underlying glass serving as an etch stop. After bonding on a transparent glass cover plate, one obtains a micromodel in oxygen impermeable materials with water-wet surfaces where the microfluidic channels are transparent and structural elements such as the pillars creating the pore network are opaque. The advantageous features of this approach in a chemical imaging application are demonstrated by incorporating a Pt porphyrin fluorophore in a PDMS film serving as the oxygen-sensing layer and a bonding surface, or in a polystyrene film coated with a PDMS layer for bonding. The sensing of a dissolved oxygen gradient was demonstrated using fluorescence lifetime imaging, and it is shown that different matrix polymers lead to optimal use in different ranges of oxygen concentration. Imaging with the opaque pillars in between the observation direction and the continuous fluorophore film yields images that retain defined spatial structure in the sensor image. PMID:22995983

  20. Silicon-on-glass pore network micromodels with oxygen-sensing fluorophore films for chemical imaging and defined spatial structure

    SciTech Connect

    Grate, Jay W.; Kelly, Ryan T.; Suter, Jonathan D.; Anheier, Norman C.

    2012-11-21

    Pore network microfluidic models were fabricated by a silicon-on-glass technique that provides the precision advantage of dry etched silicon while creating a structure that is transparent across all microfluidic channels and pores, and can be imaged from either side. A silicon layer is bonded to an underlying borosilicate glass substrate and thinned to the desired height of the microfluidic channels and pores. The silicon is then patterned and through-etched by deep reactive ion etching (DRIE), with the underlying glass serving as an etch stop. After bonding on a transparent glass cover plate, one obtains a micromodel in oxygen impermeable materials with water wet surfaces where the microfluidic channels are transparent and structural elements such as the pillars creating the pore network are opaque. The micromodel can be imaged from either side. The advantageous features of this approach in a chemical imaging application are demonstrated by incorporating a Pt porphyrin fluorophore in a PDMS film serving as the oxygen sensing layer and a bonding surface, or in a polystyrene film coated with a PDMS layer for bonding. The sensing of a dissolved oxygen gradient was demonstrated using fluorescence lifetime imaging, and it is shown that different matrix polymers lead to optimal use in different ranges dissolved oxygen concentration. Imaging with the opaque pillars in between the observation direction and the continuous fluorophore film yields images that retain spatial information in the sensor image.

  1. 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. PMID:25845499

  2. Severe Acute Respiratory Failure due to Inhalation of Baby Powder and Successfully Treated with Venous-Venous Extracorporeal Membrane Oxygenation.

    PubMed

    Panarello, Giovanna; Occhipinti, Giovanna; Piazza, Marcello; Capitanio, Guido; Vitulo, Patrizio; Gridelli, Bruno; Pilato, Michele; Arcadipane, Antonio

    2015-12-15

    Accidental inhalation of powder is a potential problem for infants. The clinical effects of inhaling powder depend on the powder contents, degree of aspiration, and the child's underlying systemic response. We present a case of accidental inhalation of rice starch powder in a 17-month-old girl, which led to severe acute respiratory distress syndrome responsive to conventional treatment, ultimately requiring venous-venous extracorporeal membrane oxygenation. PMID:26657704

  3. Cardiac oxygen limitation during an acute thermal challenge in the European perch: effects of chronic environmental warming and experimental hyperoxia.

    PubMed

    Ekström, Andreas; Brijs, Jeroen; Clark, Timothy D; Gräns, Albin; Jutfelt, Fredrik; Sandblom, Erik

    2016-08-01

    Oxygen supply to the heart has been hypothesized to limit cardiac performance and whole animal acute thermal tolerance (CTmax) in fish. We tested these hypotheses by continuously measuring venous oxygen tension (Pvo2) and cardiovascular variables in vivo during acute warming in European perch (Perca fluviatilis) from a reference area during summer (18°C) and a chronically heated area (Biotest enclosure) that receives warm effluent water from a nuclear power plant and is normally 5-10°C above ambient (24°C at the time of experiments). While CTmax was 2.2°C higher in Biotest compared with reference perch, the peaks in cardiac output and heart rate prior to CTmax occurred at statistically similar Pvo2 values (2.3-4.0 kPa), suggesting that cardiac failure occurred at a common critical Pvo2 threshold. Environmental hyperoxia (200% air saturation) increased Pvo2 across temperatures in reference fish, but heart rate still declined at a similar temperature. CTmax of reference fish increased slightly (by 0.9°C) in hyperoxia, but remained significantly lower than in Biotest fish despite an improved cardiac output due to an elevated stroke volume. Thus, while cardiac oxygen supply appears critical to elevate stroke volume at high temperatures, oxygen limitation may not explain the bradycardia and arrhythmia that occur prior to CTmax Acute thermal tolerance and its thermal plasticity can, therefore, only be partially attributed to cardiac failure from myocardial oxygen limitations, and likely involves limiting factors on multiple organizational levels. PMID:27280433

  4. A new method to detect rapid oxygen changes around cells: How quickly do calcium channels sense oxygen in cardiomyocytes?

    PubMed Central

    Scaringi, John A.; Rosa, Angelo Oscar; Morad, Martin

    2013-01-01

    Acute hypoxia is thought to trigger protective responses that, in tissues like heart and carotid body, include rapid (5–10 s) suppression of Ca2+ and K+ channels. To gain insight into the mechanism for the suppression of the cardiac l-type Ca2+ channel, we measured O2-dependent fluorescence in the immediate vicinity of voltage-clamped cardiac cells subjected to rapid exchange of solutions with different O2 tensions. This was accomplished with an experimental chamber with a glass bottom that was used as a light guide for excitation of a thin ruthenium-based O2-sensitive ORMOSIL coating. Fluorescence imaging showed that steady-state Po2 was well controlled within the entire stream from an electromagnetically controlled solution “puffer” but that changes were slower at the periphery of the stream (τ1/2 ∼ 500 ms) than immediately around the voltage-clamped myocyte (τ1/2 ∼ 225 ms) where, in turn, firmly attached cells produced an additional local delay of 50–100 ms. Performing simultaneous voltage clamp and O2 measurements, we found that acute hypoxia gradually and reversibly suppressed the Ca2+ channel (CaV1.2). Using Ba2+ as charge carrier, the suppression was significant after 1.5 s, reached ∼10% after 2.5 s, and was nearly completely reversible in 5 s. The described fluorescence measurements provide the means to check and fine tune solution puffers and suggest that changes in Po2 can be accomplished within ∼200 ms. The rapid and reversible suppression of barium current under hypoxia is consistent with the notion that the cardiac Ca2+ channel is directly modulated by O2. PMID:24157525

  5. Predictors of Acute Renal Failure During Extracorporeal Membrane Oxygenation in Pediatric Patients After Cardiac Surgery.

    PubMed

    Lv, Lin; Long, Cun; Liu, Jinping; Hei, Feilong; Ji, Bingyang; Yu, Kun; Hu, Qiang; Hu, Jinxiao; Yuan, Yuan; Gao, Guodong

    2016-05-01

    Acute renal failure (ARF) is associated with increased mortality in pediatric extracorporeal membrane oxygenation (ECMO). The aim of this study was to identify predictors of ARF during ECMO in pediatric patients after cardiac surgery. A retrospective study analyzed 42 children (≤15 years) after cardiac surgery requiring venous-arterial ECMO between December 2008 and December 2014 at Fuwai Hospital. ARF was defined as ≥300% rise in serum creatinine (SCr) concentration from baseline or application of dialysis. Multivariate logistic regression was performed to identify the predictors of ARF during ECMO. A total of 42 children (age, interquartile range [IQR], 13.0 [7.2-29.8] months; weight, IQR, 8.5 [6.7-11.0] kg) after cardiac surgery requiring ECMO were included in this study. The total survival rate was 52.4%, and the incidence of ARF was 40.5%. As the result of univariate analysis, ECMO duration, cardiopulmonary resuscitation, maximum free hemoglobin (FHB) during ECMO, lactate level, and mean blood pressure before initiation of ECMO were entered in multiple logistic regression analysis. In multiple logistic regression analysis, FHB during ECMO (OR 1.136, 95% CI 1.023-1.261) and lactate level before initiation of ECMO (OR 1.602, 95% CI 1.025-2.502) were risk factors for ARF during ECMO after pediatric cardiac surgery. There was a linear correlation between maximum SCr and maximum FHB (Pearson's r = 0.535, P = 0.001). Maximum SCr during ECMO has also a linear correlation with lactate level before initiation of ECMO (Pearson's r = 0.342, P = 0.044). Increased FHB during ECMO and high lactate level before initiation of ECMO were risk factors for ARF during ECMO in pediatric patients after cardiac surgery. PMID:26636965

  6. Combined venoarterial extracorporeal membrane oxygenation and transcatheter aortic valve implantation for the treatment of acute aortic prosthesis dysfunction in a high-risk patient.

    PubMed

    Pergolini, Amedeo; Zampi, Giordano; Tinti, Maria Denitza; Polizzi, Vincenzo; Pino, Paolo Giuseppe; Pontillo, Daniele; Musumeci, Francesco; Luzi, Giampaolo

    2016-01-01

    We describe the case of a patient with acute bioprosthesis dysfunction in cardiogenic shock, in whom hemodynamic support was provided by venoarterial extracorporeal membrane oxygenation, and successfully treated by transcatheter aortic valve implantation. PMID:27402446

  7. Gas sensing in microplates with optodes: influence of oxygen exchange between sample, air, and plate material.

    PubMed

    Arain, Sarina; Weiss, Svenja; Heinzle, Elmar; John, Gernot T; Krause, Christian; Klimant, Ingo

    2005-05-01

    Microplates with integrated optical oxygen sensors are a new tool to study metabolic rates and enzyme activities. Precise measurements are possible only if oxygen exchange between the sample and the environment is known. In this study we quantify gas exchange in plastic microplates. Dissolved oxygen was detected using either an oxygen-sensitive film fixed at the bottom of each well or a needle-type sensor. The diffusion of oxygen into wells sealed with different foils, paraffin oil, and paraffin wax, respectively, was quantified. Although foil covers showed the lowest oxygen permeability, they include an inevitable gas phase between sample and sealing and are difficult to manage. The use of oil was found to be critical due to the extensive shaking caused by movement of the plates during measurements in microplate readers. Thus, paraffin wax was the choice material because it avoids convection of the sample and is easy to handle. Furthermore, without shaking, significant gradients in pO2 levels within a single well of a polystyrene microplate covered with paraffin oil were detected with the needle-type sensor. Higher pO2 levels were obtained near the surface of the sample as well as near the wall of the well. A significant diffusion of oxygen through the plastic plate material was found using plates based on polystyrene. Thus, the location of a sensor element within the well has an effect on the measured pO2 level. Using a sensor film fixed on the bottom of a well or using a dissolved pO2-sensitive indicator results in pO2 offset and in apparently lower respiration rates or enzyme activities. Oxygen diffusion through a polystyrene microplate was simulated for measurements without convection--that is, for samples without oxygen diffusion through the cover and for unshaken measurements using permeable sealings. This mathematical model allows for calculation of the correct kinetic parameters. PMID:15772950

  8. The regulation of pulmonary inflammation by the hypoxia-inducible factor-hydroxylase oxygen-sensing pathway.

    PubMed

    Whyte, Moira K B; Walmsley, Sarah R

    2014-12-01

    Although the hypoxia-inducible factor (HIF)-hydroxylase oxygen-sensing pathway has been extensively reviewed in the context of cellular responses to hypoxia and cancer biology, its importance in regulating innate immune biology is less well described. In this review, we focus on the role of the HIF-hydroxylase pathway in regulating myeloid cell responses and its relevance to inflammatory lung disease. The more specific roles of individual HIF/ prolyl hydroxylase pathway members in vivo are discussed in the context of lineage-specific rodent models of inflammation, with final reference made to the therapeutic challenges of targeting the HIF/hydroxylase pathway in immune cells. PMID:25525731

  9. Microwave-assisted synthesis of SnO2 nanorods for oxygen gas sensing at room temperature

    PubMed Central

    Azam, Ameer; Habib, Sami S; Salah, Numan A; Ahmed, Faheem

    2013-01-01

    High-quality single-crystalline SnO2 nanorods were synthesized using a microwave-assisted solution method. The nanorods were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), ultraviolet-visible and Raman spectroscopy, Brunauer–Emmett–Teller (BET), and electrical resistance measurements. The XRD pattern indicated the formation of single-phase SnO2 nanorods with rutile structure. FE-SEM and TEM images revealed tetragonal nanorods of about 450–500 nm in length and 60–80 nm in diameter. The nanorods showed a higher BET surface area of 288 m2/g, much higher than that of previously reported work. The Raman scattering spectra indicated a typical rutile phase of the SnO2. The absorption spectrum showed an absorption peak centered at 340 nm, and the band-gap value was found to be 3.64 eV. The gas-sensing properties of the SnO2 nanorods for oxygen gas with different concentrations were measured at room temperature. It was found that the value of resistance increased with the increase in oxygen gas concentration in the test chamber. The SnO2 nanorods exhibited high sensitivity and rapid response-recovery characteristics to oxygen gas, and could detect oxygen concentration as low as 1, 3, 5, and 10 ppm. PMID:24143091

  10. Evaluation of Intrarenal Oxygenation in Iodinated Contrast-Induced Acute Kidney Injury–Susceptible Rats by Blood Oxygen Level–Dependent Magnetic Resonance Imaging

    PubMed Central

    Li, Lu-Ping; Lu, Jing; Zhou, Ying; Papadopoulou, Maria V.; Franklin, Tammy; Bokhary, Ujala; Solomon, Richard; Sen, Anindya; Prasad, Pottumarthi V.

    2016-01-01

    Objectives The objectives of this study were to evaluate differences in intrarenal oxygenation as assessed by blood oxygen level–dependent (BOLD) magnetic resonance imaging in contrast-induced acute kidney injury (CIAKI)–susceptible rats when using 4 contrast media with different physicochemical properties and to demonstrate the feasibility of acquiring urinary neutrophil gelatinase–associated lipocalin (NGAL) levels as a marker of CIAKI in this model. Materials and Methods Our institutional animal care and use committee approved the study. Sixty-six Sprague-Dawley rats were divided into CIAKI-susceptible groups (received nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester [10 mg/kg] and cycloxygenase inhibitor indomethacin [10mg/kg]) and control groups (received saline instead). One of the 4 iodinated contrast agents (iothalamate, iohexol, ioxaglate, or iodixanol) was then administered (1600-mg organic iodine per kilogram of body weight). Multiple blood oxygen level–dependent magnetic resonance images were acquired on a Siemens 3.0-T scanner using a multiple gradient recalled echo sequence at baseline, after N-nitro-L-arginine methyl ester (or saline), indomethacin (or saline), and iodinated contrast agent (or placebo). R2* (R2* = 1/T2*) maps were generated inline on the scanner. A mixed-effects growth curve model with first-order autoregressive variance-covariance was used to analyze the temporal data. Urinary NGAL, a marker of kidney injury (unlike serum creatinine), was measured 4 hours after contrast injection in the 2 subgroups. Results Differences in blood oxygen level–dependent magnetic resonance imaging results between the contrast media were observed in all 4 renal regions. However, the inner stripe of the outer medulla (ISOM) showed the most pronounced changes in the CIAKI-susceptible group and R2* increased significantly (P < 0.01) over time with all 4 contrast media. In the control groups, only iodixanol showed an increase in R2

  11. Dissolved oxygen sensing using an optical fibre long period grating coated with hemoglobin

    NASA Astrophysics Data System (ADS)

    Partridge, M.; James, S. W.; Tatam, R. P.

    2015-09-01

    A method for the preparation of a sensor consisting of an optical fibre long period grating coated with human hemoglobin is described. The utility of this sensor in detecting dissolved oxygen in phosphate buffered saline solution, by the conversion of the coated hemoglobin from deoxyhemoglobin to oxyhemoglobin, is described. The sensor shows good repeatability with a %CV of less than 1% for oxygenated and deoxygenated states and no drift or hysteresis with repeated cycling.

  12. FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

    2005-04-01

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. One of the critical materials issues is to demonstrate that the luminescent cluster immobilized in the sol-gel porous support can withstand high temperature. At the same time the sol-gel matrix must have a high permeability to oxygen. Using a potassium salt of the molybdenum clusters, K{sub 2}Mo{sub 6}Cl{sub 14}, we have established the conditions necessary for deposition of optical quality sol-gel films. From spectroscopic measurements of the film we have shown that the cluster luminescence is stable following heat cycling of 54 hours at 200 C. Quenching of a factor of 1.5X between pure nitrogen and 21% oxygen was observed from in-situ measurements of films heated directly at 200 C. An automated system for characterizing fiber optic oxygen sensors up to 220 C with a temporal resolution better than 10 s is under construction. We estimate a signal of 6 x 10{sup 8} photons/s after complete quenching in 21% oxygen. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

  13. The Stroke Oxygen Pilot Study: A Randomized Controlled Trial of the Effects of Routine Oxygen Supplementation Early after Acute Stroke—Effect on Key Outcomes at Six Months

    PubMed Central

    Ali, Khalid; Warusevitane, Anushka; Lally, Frank; Sim, Julius; Sills, Sheila; Pountain, Sarah; Nevatte, Tracy; Allen, Martin; Roffe, Christine

    2013-01-01

    Introduction Post-stroke hypoxia is common, and may adversely affect outcome. We have recently shown that oxygen supplementation may improve early neurological recovery. Here, we report the six-month outcomes of this pilot study. Methods Patients with a clinical diagnosis of acute stroke were randomized within 24 h of admission to oxygen supplementation at 2 or 3 L/min for 72 h or to control treatment (room air). Outcomes (see below) were assessed by postal questionnaire at 6 months. Analysis was by intention-to-treat, and statistical significance was set at p≤0.05. Results Out of 301 patients randomized two refused/withdrew consent and 289 (148 in the oxygen and 141 in the control group) were included in the analysis: males 44%, 51%; mean (SD) age 73 (12), 71 (12); median (IQR) National Institutes of Health Stroke Scale score 6 (3, 10), 5 (3, 10) for the two groups respectively. At six months 22 (15%) patients in the oxygen group and 20 (14%) in the control group had died; mean survival in both groups was 162 days (p = 0.99). Median (IQR) scores for the primary outcome, the modified Rankin Scale, were 3 (1, 5) and 3 (1, 4) for the oxygen and control groups respectively. The covariate-adjusted odds ratio was 1.04 (95% CI 0.67, 1.60), indicating that the odds of a lower (i.e. better) score were non-significantly higher in the oxygen group (p = 0.86). The mean differences in the ability to perform basic (Barthel Index) and extended activities of daily living (NEADL), and quality of life (EuroQol) were also non-significant. Conclusions None of the key outcomes differed at 6 months between the groups. Although not statistically significant and generally of small magnitude, the effects were predominantly in favour of the oxygen group; a larger trial, powered to show differences in longer-term functional outcomes, is now on-going. Trial Registration Controlled-Trials.com ISRCTN12362720; Eudract.ema.europa.eu 2004-001866-41 PMID:23755093

  14. 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.

  15. Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

    2006-05-01

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we described a particle-in-binder approach to immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the tips of optical fibers. Compared to previous methods, the particle-in-binder approach affords fibers with greatly improved mechanical properties. The response of the sensor to oxygen at 40, 70 and 100 C was measured in 2-21% gas phase oxygen. The normalized sensor signal is linear with molar oxygen concentration and fits the theoretical Stern-Volmer relationship. Although the sensitivity decreases with temperature, at 100 C the sensitivity is 160 [O{sub 2}]{sup -1}. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

  16. Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn; Po Zhang

    2006-06-30

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Our approach towards immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the far end of an optical fiber is to embed the cluster in a thermally cured sol-gel matrix particle. This particle-in-binder approach affords fibers with greatly improved mechanical properties, as compared to previous approaches. The sensor was characterized in 2-21% gas phase oxygen at 40, 70 and 100 C. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

  17. 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.

  18. Severe Tumor Lysis Syndrome and Acute Pulmonary Edema Requiring Extracorporeal Membrane Oxygenation Following Initiation of Chemotherapy for Metastatic Alveolar Rhabdomyosarcoma.

    PubMed

    Sanford, Ethan; Wolbrink, Traci; Mack, Jennifer; Grant Rowe, R

    2016-05-01

    We present an 8-year-old male with metastatic alveolar rhabdomyosarcoma (ARMS) who developed precipitous cardiopulmonary collapse with severe tumor lysis syndrome (TLS) 48 hr after initiation of chemotherapy. Despite no detectable pulmonary metastases, acute hypoxemic respiratory failure developed, requiring extracorporeal membrane oxygenation (ECMO). Although TLS has been reported in disseminated ARMS, this singular case of life-threatening respiratory deterioration developing after initiation of chemotherapy presented unique therapeutic dilemmas. We review the clinical aspects of this case, including possible mechanisms of respiratory failure, and discuss the role of ECMO utilization in pediatric oncology. PMID:26713672

  19. A 2.0 and 4.7 Heterodyne Spectrometer for Lower Thermospheric Wind, Temperature, and Atomic Oxygen Density Sensing

    NASA Astrophysics Data System (ADS)

    Yee, J.; Wu, D. L.; Mehdi, I.; Schlecht, E.; Demajistre, R.; Talaat, E. R.

    2013-12-01

    In this paper, we will present the concept of a high-sensitivity heterodyne spectrometer operating at Terahertz (THz) frequency for global lower thermospheric neutral wind, temperature and atomic oxygen density measurements from a low earth orbit. These critical measurements are needed to better understand underlying mechanisms of the upper atmospheric composition/dynamics/temperature variability and the role of neutral dynamics on the ionospheric variability. Currently, no reliable satellite remote sensing technique can provide these measurements globally in the critical 100-150 km altitude region with complete local time coverage and desired spatial resolution, precision and accuracy. The instrument, THz Limb Sounder (TLS), to be developed under NASA's Geospace Instrument Development and Enabling Science Program, is aimed to provide, for the first time, global neutral wind/temperature/density profile measurements during day and night, with focus at altitudes of 100-150 km where most of the ion-neutral energy/momentum couplings take place. The TLS concept extends the limb sounding technique employed by Microwave Limb Sounder (MLS) for density/temperature/wind measurements by resolving the Doppler line shape of atomic oxygen fine structure emission at 2.0 and 4.7 THz (145 and 63 microns). These two atomic oxygen line emissions are very bright and distributed nearly uniformly globally (at all latitudes including high latitude particle precipitation regions) and temporally (at all local times during both day and night), thus ideal for thermospheric remote sensing. The TLS instrument concept, measurement methodology, and the expected performance will be presented and discussed in this paper.

  20. The acute antinociceptive effect of hyperbaric oxygen is not accompanied by an increase in markers of oxidative stress

    PubMed Central

    Liu, Shulin; Shirachi, Donald Y.; Quock, Raymond M.

    2014-01-01

    Aims Exposure to hyperbaric oxygen (HBO2) causes an antinociceptive response in mice. However, breathing oxygen (O2) at an elevated pressure can potentially cause oxygen toxicity. The aim of this study was to identify the determinants of HBO2 antinociception and the toxicity profile of HBO2. Main methods Male NIH Swiss mice were assessed for acute antinociceptive responsiveness under room air or 100% O2 at 1.0 or 3.5 atmospheres absolute (ATA), using the acetic acid-induced abdominal constriction test. For the oxygen toxicity test, mice were exposed to 3.5 ATA oxygen for 11 min, 60 min, 60 min daily for 2 days (120 min) or 60 min daily for 4 days (240 min), then assessed by analyzing the levels of two oxidative stress markers, MDA (malondialdehyde) and protein carbonyl in brain, spinal cord and lung. Key Findings Only the combination of 100% O2 and 3.5 ATA caused significant antinociception. The antinociceptive effect of 100% O2 was pressure-dependent up to 3.5 ATA. In the oxygen toxicity test, mice exposed to HBO2 for different time intervals had levels of brain, spinal cord and lung MDA and protein carbonyl that were comparable to that of control animals exposed to room air. Significance Treatment with 100% O2 evokes a pressure-dependent antinociceptive effect. Since there was no significant increase in levels of the oxidative stress markers in the tested tissues, it is concluded HBO2 at 3.5 ATA produces antinociception in the absence of oxidative stress in mice. PMID:24418003

  1. Improvement of Oxygenation in Severe Acute Respiratory Distress Syndrome With High-Volume Continuous Veno-venous Hemofiltration

    PubMed Central

    Yang, Wenmin; Hong, Jie; Zeng, Qiyi; Tao, Jianping; Chen, Feiyan; Dang, Run; Liang, Yufeng; Wu, Zhiyuan; Yang, Yiyu

    2016-01-01

    The efficacy and therapeutic mechanisms of continuous renal replacement therapy (CRRT) for improvement of oxygenation in acute respiratory distress syndrome (ARDS) remain controversial. These questions were addressed by retrospective analysis of severe ARDS patients admitted to the pediatric intensive care unit of our hospital from 2009 to 2015 who received high-volume continuous veno-venous hemofiltration during mechanical ventilation. There was a significant improvement in partial oxygen pressure/fraction of inspired oxygen (PaO2/FiO2) 24 hours after CRRT onset compared with baseline (median change = 51.5; range = −19 to 450.5; P < .001) as well as decreases in FiO2, peak inspiratory pressure, positive end-expiratory pressure, and mean airway pressure (P < .05). The majority of patients had a negative fluid balance after 24 hours of CRRT. White blood cell (WBC) count decreased in the subgroup with high baseline WBC count (P < .05). PaO2/FiO2 was higher in ARDS patients with extrapulmonary etiology than in those with pulmonary etiology (P < .05). Improvement in oxygenation is likely related to both restoration of fluid balance and clearance of inflammatory mediators. PMID:27336018

  2. FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

    2005-01-01

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. One of the critical materials issues is to demonstrate that the luminescent cluster immobilized in the sol-gel porous support can withstand high temperature. At the same time the sol-gel matrix must have a high permeability to oxygen. Using a potassium salt of the molybdenum clusters, K{sub 2}Mo{sub 6}Cl{sub 14}, we have established the conditions necessary for deposition of optical quality sol-gel films. From spectroscopic measurements of the film we have shown that the cluster luminescence is stable following heat cycling of 1 hour at 250 C. Quenching of a factor of 4X between pure nitrogen and 21% oxygen was observed for films cured directly at 200 C. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

  3. Human oxygen sensing may have origins in prokaryotic elongation factor Tu prolyl-hydroxylation

    PubMed Central

    Scotti, John S.; Leung, Ivanhoe K. H.; Ge, Wei; Bentley, Michael A.; Paps, Jordi; Kramer, Holger B.; Lee, Joongoo; Aik, WeiShen; Choi, Hwanho; Paulsen, Steinar M.; Bowman, Lesley A. H.; Loik, Nikita D.; Horita, Shoichiro; Ho, Chia-hua; Kershaw, Nadia J.; Tang, Christoph M.; Claridge, Timothy D. W.; Preston, Gail M.; McDonough, Michael A.; Schofield, Christopher J.

    2014-01-01

    The roles of 2-oxoglutarate (2OG)-dependent prolyl-hydroxylases in eukaryotes include collagen stabilization, hypoxia sensing, and translational regulation. The hypoxia-inducible factor (HIF) sensing system is conserved in animals, but not in other organisms. However, bioinformatics imply that 2OG-dependent prolyl-hydroxylases (PHDs) homologous to those acting as sensing components for the HIF system in animals occur in prokaryotes. We report cellular, biochemical, and crystallographic analyses revealing that Pseudomonas prolyl-hydroxylase domain containing protein (PPHD) contain a 2OG oxygenase related in structure and function to the animal PHDs. A Pseudomonas aeruginosa PPHD knockout mutant displays impaired growth in the presence of iron chelators and increased production of the virulence factor pyocyanin. We identify elongation factor Tu (EF-Tu) as a PPHD substrate, which undergoes prolyl-4-hydroxylation on its switch I loop. A crystal structure of PPHD reveals striking similarity to human PHD2 and a Chlamydomonas reinhardtii prolyl-4-hydroxylase. A crystal structure of PPHD complexed with intact EF-Tu reveals that major conformational changes occur in both PPHD and EF-Tu, including a >20-Å movement of the EF-Tu switch I loop. Comparison of the PPHD structures with those of HIF and collagen PHDs reveals conservation in substrate recognition despite diverse biological roles and origins. The observed changes will be useful in designing new types of 2OG oxygenase inhibitors based on various conformational states, rather than active site iron chelators, which make up most reported 2OG oxygenase inhibitors. Structurally informed phylogenetic analyses suggest that the role of prolyl-hydroxylation in human hypoxia sensing has ancient origins. PMID:25197067

  4. Protein kinase G-regulated production of H2S governs oxygen sensing.

    PubMed

    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

    2015-04-21

    Reflexes initiated by the carotid body, the principal O2-sensing organ, are critical for maintaining cardiorespiratory 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 (Cys(265) and Cys(282)) of HO-2. CO stimulated protein kinase G (PKG)-dependent phosphorylation of Ser(377) 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

  5. Low-cost microarray thin-film electrodes with ionic liquid gel-polymer electrolytes for miniaturised oxygen sensing.

    PubMed

    Lee, Junqiao; Silvester, Debbie S

    2016-06-21

    A robust, miniaturised electrochemical gas sensor for oxygen (O2) has been constructed using a commercially available Pt microarray thin-film electrode (MATFE) with a gellified electrolyte containing the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) and poly(methyl methacrylate) (PMMA) in a 50 : 50 mass ratio. Diffusion coefficients and solubilities for oxygen in mixtures of PMMA/RTIL at different PMMA doping concentrations (0-50% mass) were derived from potential step chronoamperometry (PSCA) on a Pt microdisk electrode. The MATFE was then used with both the neat RTIL and 50% (by mass) PMMA/RTIL gel, to study the analytical behavior over a wide concentration range (0.1 to 100 vol% O2). Cyclic voltammetry (CV) and long-term chronoamperometry (LTCA) techniques were employed and it was determined that the gentler CV technique is better at higher O2 concentrations (above 60 vol%), but LTCA is more reliable and accurate at lower concentrations (especially below 0.5% O2). In particular, there was much less potential shifting (from the unstable Pt quasi-reference electrode) evident in the 50% PMMA/RTIL gel than in the neat RTIL, making this a much more suitable electrolyte for long-term continuous oxygen monitoring. The mass production and low-cost of the electrode array, along with the minimal amounts of RTIL/PMMA required, make this a viable sensing device for oxygen detection on a bulk scale in a wide range of environmental conditions. PMID:26931642

  6. Modulation of Type I Interferon-Associated Viral Sensing during Acute Simian Immunodeficiency Virus Infection in African Green Monkeys

    PubMed Central

    Jochems, Simon P.; Petitjean, Gaël; Kunkel, Désirée; Liovat, Anne-Sophie; Ploquin, Mickaël J.; Barré-Sinoussi, Françoise; Lebon, Pierre; Jacquelin, Béatrice

    2014-01-01

    ABSTRACT Natural hosts of simian immunodeficiency virus (SIV), such as African green monkeys (AGMs), do not progress to AIDS when infected with SIV. This is associated with an absence of a chronic type I interferon (IFN-I) signature. It is unclear how the IFN-I response is downmodulated in AGMs. We longitudinally assessed the capacity of AGM blood cells to produce IFN-I in response to SIV and herpes simplex virus (HSV) infection. Phenotypes and functions of plasmacytoid dendritic cells (pDCs) and other mononuclear blood cells were assessed by flow cytometry, and expression of viral sensors was measured by reverse transcription-PCR. pDCs displayed low BDCA-2, CD40, and HLA-DR expression levels during AGM acute SIV (SIVagm) infection. BDCA-2 was required for sensing of SIV, but not of HSV, by pDCs. In acute infection, AGM peripheral blood mononuclear cells (PBMCs) produced less IFN-I upon SIV stimulation. In the chronic phase, the production was normal, confirming that the lack of chronic inflammation is not due to a sensing defect of pDCs. In contrast to stimulation by SIV, more IFN-I was produced upon HSV stimulation of PBMCs isolated during acute infection, while the frequency of AGM pDCs producing IFN-I upon in vitro stimulation with HSV was diminished. Indeed, other cells started producing IFN-I. This increased viral sensing by non-pDCs was associated with an upregulation of Toll-like receptor 3 and IFN-γ-inducible protein 16 caused by IFN-I in acute SIVagm infection. Our results suggest that, as in pathogenic SIVmac infection, SIVagm infection mobilizes bone marrow precursor pDCs. Moreover, we show that SIV infection modifies the capacity of viral sensing in cells other than pDCs, which could drive IFN-I production in specific settings. IMPORTANCE The effects of HIV/SIV infections on the capacity of plasmacytoid dendritic cells (pDCs) to produce IFN-I in vivo are still incompletely defined. As IFN-I can restrict viral replication, contribute to inflammation

  7. EDTA-Decorated Nanostructured ZnO/CdS Thin Films for Oxygen Gas Sensing Applications

    NASA Astrophysics Data System (ADS)

    Arunraja, L.; Thirumoorthy, P.; Karthik, A.; Rajendran, V.; Edwinpaul, L.

    2016-08-01

    ZnO/CdS and ZnO/CdS-EDTA nanostructured thin films were prepared on a glass substrate using spin-coating and used for oxygen gas sensor applications. The structural properties of both ZnO/CdS and ZnO/CdS-EDTA nanostructured composites were comparatively characterized. The nanostructure thin film was found in a hexagonal structure with an average crystallite size reduced from 77 nm to 29 nm due to the influence of the EDTA. The optical absorption, photo luminescence, functional groups and surface morphology of the nanostructured thin films were comprehensively investigated. Oxygen was suitably tailored to verify the sensor response over a concentration range of 10-50 ppm at room temperature. Thus, the sensor studies reveal that the performance, response, and recovery time were enhanced in ZnO/CdS-EDTA nanostructured thin film compared with ZnO/CdS.

  8. Chromatin and oxygen sensing in the context of JmjC histone demethylases

    PubMed Central

    Shmakova, Alena; Batie, Michael; Druker, Jimena; Rocha, Sonia

    2014-01-01

    Responding appropriately to changes in oxygen availability is essential for multicellular organism survival. Molecularly, cells have evolved intricate gene expression programmes to handle this stressful condition. Although it is appreciated that gene expression is co-ordinated by changes in transcription and translation in hypoxia, much less is known about how chromatin changes allow for transcription to take place. The missing link between co-ordinating chromatin structure and the hypoxia-induced transcriptional programme could be in the form of a class of dioxygenases called JmjC (Jumonji C) enzymes, the majority of which are histone demethylases. In the present review, we will focus on the function of JmjC histone demethylases, and how these could act as oxygen sensors for chromatin in hypoxia. The current knowledge concerning the role of JmjC histone demethylases in the process of organism development and human disease will also be reviewed. PMID:25145438

  9. Determination of atomic oxygen density and temperature of the thermosphere by remote sensing

    NASA Astrophysics Data System (ADS)

    Sharma, Ramesh D.; Harlow, Harry B.; Riehl, James P.

    1988-06-01

    Measurement of emission from the earth's atmosphere in the far infrared due to transitions between fine structure levels of the ground state (3P) of atomic oxygen at 63 microns, (3P1 to 3P2) and 147 microns (3P0 to 3P1) is proposed. These magnetic-dipole allowed transitions with long radiative lifetimes (about 3.2 h for the 63 micron transition and about 16.3 h for the 147 micron transition) are assumed to be in equilibrium with the local translational temperature. A one-dimensional onion-peel inversion of the limb emissions at 63 and 147 microns from a model atmosphere is shown to yield reasonable results for both the temperature and atomic oxygen density in the 90-250 km altitude range.

  10. Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D. J. Osborn; Po Zhang

    2006-09-30

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Our approach towards immobilizing the potassium salt of the molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the far end of an optical fiber is to embed the cluster in a thermally cured sol-gel matrix particle. Due to the improved mechanical properties of this approach high temperature sensor measurements were performed up to 100 C. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

  11. Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

    2006-01-01

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we described a particle-in-binder approach to immobilizing the potassium salt of a molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the tips of optical fibers. Compared to previous methods, the particle-in-binder approach affords fibers with greatly improved mechanical properties. We have extensively characterized two fiber sensors at high temperature. We obtain quenching ratios between pure nitrogen and 21% oxygen as high as 3.9 x at 70 C. For the first sensor at 60 C we obtained a {+-} 1% variation in the quenching ratio over 6 cycles of measurement, and monitored the device performance over 23 days. We were able to operate the second sensor continuously for 14 hours at 70 C, and the sensor quenching ratio was stable to 5% over that time period. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

  12. Analytical and mechanistic aspects of the room temperature phosphorescence of Erythrosine B adsorbed on solid supports as oxygen sensing phases

    NASA Astrophysics Data System (ADS)

    Velasco-García, Nieves; Pereiro-García, Rosario; Diaz-García, Marta E.

    1995-05-01

    Room temperature phosphorescence (RTP) lifetime measurements and spectra of different concentrations of Erythrosine B immobilized on anion exchangers and non-ionic resins have been employed to unveil mechanistic aspects of the RTP of immobilized Erythrosine B. The existence of a definite number of RTP decaying components in some experimental conditions has been confirmed. The effects of humidified argon and air on RTP lifetimes and the changes in luminescence intensities were used to investigate some of the interactions responsible for the multiple component RTP emission. The experiments performed also proved the suitability of the phases prepared using non-ionic resins, for the quantification of molecular oxygen by RTP-quenching measurements. Moreover, the solid phases with anion-exchanger resins showed good potential for the analytical sensing of humidity.

  13. Role of ammonia, inflammation, and cerebral oxygenation in brain dysfunction of acute-on-chronic liver failure patients.

    PubMed

    Sawhney, Rohit; Holland-Fischer, Peter; Rosselli, Matteo; Mookerjee, Rajeshwar P; Agarwal, Banwari; Jalan, Rajiv

    2016-06-01

    Hepatic encephalopathy (HE) is a common feature of acute-on-chronic liver failure (ACLF). Although ammonia, inflammation, and cerebral oxygenation are associated with HE in acute liver failure, their roles in ACLF are unknown. The aim of this prospective, longitudinal study was to determine the role of these pathophysiological variables in ACLF patients with and without HE. We studied 101 patients with ACLF admitted to the intensive care unit. Severity of ACLF and HE, arterial ammonia, jugular venous oxygen saturation (JVO2 ), white blood cell count (WCC), and C-reactive protein were measured at days 0, 1, 3, and 7. Patients were followed until death or hospital discharge. Mortality was high (51 patients, 50.5%), especially in patients with HE of whom 35 of 53 (66.0%) died regardless of ACLF severity. At baseline, increased WCC and abnormal JVO2 (high or low) were independent predictors of death. Further deterioration in inflammation, JVO2 , and ammonia were also predictive of mortality. JVO2 deviation and hyperammonemia were associated with the presence and severity of HE; improvement in these parameters was associated with a reduction in HE grade. No direct interaction was observed between these variables in regards to mortality or HE. In conclusion, this study describes potential mechanisms of HE in ACLF indicating that ammonia and abnormal cerebral oxygenation are important. The results suggest that ammonia, JVO2 , and WCC are important prognostic biomarkers and therapeutic targets. The relative roles of these pathophysiological factors in the pathogenesis of HE in ACLF or guiding therapy to improve survival requires future study. Liver Transplantation 22 732-742 2016 AASLD. PMID:27028317

  14. Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D. J. Osborn

    2003-09-30

    Spectroscopy of Mo{sub 6}Cl{sub 12} immobilized in a sol-gel matrix and heated to 200 C has been performed. Oxygen quenching of the luminescence was observed. Aging Mo{sub 6}Cl{sub 12} to temperatures above 250 C converts the canary yellow Mo{sub 6}Cl{sub 12} to a non-luminescent gray solid. Preliminary experiments point to oxidation of the clusters as the likely cause of thermally induced changes in the physical and optical properties of the clusters.

  15. 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.

  16. FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III

    2004-10-01

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. High temperature measurements of the emission of clusters in sol gel films show that the luminescence intensity from the films follow a 1/T relationship from room temperature to 150 C, and then declines at a slower rate at higher temperatures. The large number of photons available at 230 C is consistent with simple low cost optics for fiber optic probes based on the emission from clusters in sol gel films.

  17. Oxygen consumption and haematology of juvenile shortnose sturgeon Acipenser brevirostrum during an acute 24 h saltwater challenge.

    PubMed

    Penny, F M; Kieffer, J D

    2014-04-01

    This study focused on the acute physiological responses to saltwater exposure in juvenile shortnose sturgeon Acipenser brevirostrum. In two separate laboratory experiments, 2 year-old A. brevirostrum were exposed to either full (32) or half-strength (16) seawater for up to 24 h. First, oxygen consumption rates were used to estimate the metabolic costs over 24 h. Secondly, blood and muscle samples were analysed at 6, 12 and 24 h for water loss, various measures of osmoregulatory status (plasma osmolality and ions) and other standard haematological variables. Juveniles exposed to full-strength seawater showed significant decreases in oxygen consumption rates during the 24 h exposure. Furthermore, seawater-exposed fish had significantly increased plasma osmolality, ions (Na(+) and Cl(-)) and a 17% decrease in total wet mass over the 24 h exposure period. To a lesser extent, increases in osmolality, ions and mass loss were observed in fish exposed to half-strength seawater but no changes to oxygen consumption. Cortisol was also significantly increased in fish exposed to full-strength seawater. While plasma protein was elevated following 24 h in full-strength seawater, haemoglobin, haematocrit and plasma glucose levels did not change with increased salinity. These results imply an inability of juvenile A. brevirostrum to regulate water and ions in full-strength seawater within 24 h. Nonetheless, no mortality occurred in any exposure, suggesting that juvenile A. brevirostrum can tolerate short periods in saline environments. PMID:24628001

  18. Acute effects of ferumoxytol on regulation of renal hemodynamics and oxygenation.

    PubMed

    Cantow, Kathleen; Pohlmann, Andreas; Flemming, Bert; Ferrara, Fabienne; Waiczies, Sonia; Grosenick, Dirk; Niendorf, Thoralf; Seeliger, Erdmann

    2016-01-01

    The superparamagnetic iron oxide nanoparticle ferumoxytol is increasingly used as intravascular contrast agent in magnetic resonance imaging (MRI). This study details the impact of ferumoxytol on regulation of renal hemodynamics and oxygenation. In 10 anesthetized rats, a single intravenous injection of isotonic saline (used as volume control) was followed by three consecutive injections of ferumoxytol to achieve cumulative doses of 6, 10, and 41 mg Fe/kg body mass. Arterial blood pressure, renal blood flow, renal cortical and medullary perfusion and oxygen tension were continuously measured. Regulation of renal hemodynamics and oxygenation was characterized by dedicated interventions: brief periods of suprarenal aortic occlusion, hypoxia, and hyperoxia. None of the three doses of ferumoxytol resulted in significant changes in any of the measured parameters as compared to saline. Ferumoxytol did not significantly alter regulation of renal hemodynamics and oxygenation as studied by aortic occlusion and hypoxia. The only significant effect of ferumoxytol at the highest dose was a blunting of the hyperoxia-induced increase in arterial pressure. Taken together, ferumoxytol has only marginal effects on the regulation of renal hemodynamics and oxygenation. This makes ferumoxytol a prime candidate as contrast agent for renal MRI including the assessment of renal blood volume fraction. PMID:27436132

  19. Acute effects of ferumoxytol on regulation of renal hemodynamics and oxygenation

    PubMed Central

    Cantow, Kathleen; Pohlmann, Andreas; Flemming, Bert; Ferrara, Fabienne; Waiczies, Sonia; Grosenick, Dirk; Niendorf, Thoralf; Seeliger, Erdmann

    2016-01-01

    The superparamagnetic iron oxide nanoparticle ferumoxytol is increasingly used as intravascular contrast agent in magnetic resonance imaging (MRI). This study details the impact of ferumoxytol on regulation of renal hemodynamics and oxygenation. In 10 anesthetized rats, a single intravenous injection of isotonic saline (used as volume control) was followed by three consecutive injections of ferumoxytol to achieve cumulative doses of 6, 10, and 41 mg Fe/kg body mass. Arterial blood pressure, renal blood flow, renal cortical and medullary perfusion and oxygen tension were continuously measured. Regulation of renal hemodynamics and oxygenation was characterized by dedicated interventions: brief periods of suprarenal aortic occlusion, hypoxia, and hyperoxia. None of the three doses of ferumoxytol resulted in significant changes in any of the measured parameters as compared to saline. Ferumoxytol did not significantly alter regulation of renal hemodynamics and oxygenation as studied by aortic occlusion and hypoxia. The only significant effect of ferumoxytol at the highest dose was a blunting of the hyperoxia-induced increase in arterial pressure. Taken together, ferumoxytol has only marginal effects on the regulation of renal hemodynamics and oxygenation. This makes ferumoxytol a prime candidate as contrast agent for renal MRI including the assessment of renal blood volume fraction. PMID:27436132

  20. [Use of steam-oxygen tents with a universal steam generator and automatic control system in the treatment of acute stenosing laryngotracheitis in children].

    PubMed

    Taĭts, B M

    1993-01-01

    To treat acute stenosing laryngotracheitis in acute respiratory viral infection in children an original method has been developed and used for 2 years in a special hospital department. The method implies treatment of children in steam-and-oxygen tents with a universal steam-moistening generator and automatic control system. A controlled study of 50 children with acute laryngeal stenosis degree I-III confirmed high efficacy of this method permitting improvement of blood oxygenation, gas composition, acid-base condition, reduction of acidosis, prevention of exicosis and brain edema. Warm humid atmosphere promoted better discharge of the secretion and better functioning of the ciliated epithelium. Combined treatment incorporating the tents in acute laryngeal stenoses reduced lethality in severe cases, number of intubations and tracheostomies, of complications resultant from parenteral administration of the drugs. PMID:8009767

  1. FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III

    2003-07-01

    Mo{sub 6}Cl{sub 12}, a cluster compound whose luminescence depends on the ambient concentration of oxygen, is the basis for a real-time oxygen sensor for combustion applications. Previously, the properties of Mo{sub 6}Cl{sub 12} have largely been studied at room temperature; these studies have now been extended to 200 C. Optical microscopy shows that Mo{sub 6}Cl{sub 12} undergoes a steady change in color as it is heated from room temperature to 200 C, changing from canary yellow to crimson and then back to canary yellow. Concurrent thermal gravimetric analyses show a small weight loss for Mo{sub 6}Cl{sub 12} that is consistent with loss of water or HCl from the clusters. These changes are reversible. Absorption and fluorescence emission spectroscopy of Mo{sub 6}Cl{sub 12} heated to 200 C for two hours shows no change in the photophysical parameters compared to the control sample that was not heat cycled.

  2. Primary endosymbiosis and the evolution of light and oxygen sensing in photosynthetic eukaryotes

    PubMed Central

    Rockwell, Nathan C.; Lagarias, J. Clark; Bhattacharya, Debashish

    2015-01-01

    The origin of the photosynthetic organelle in eukaryotes, the plastid, changed forever the evolutionary trajectory of life on our planet. Plastids are highly specialized compartments derived from a putative single cyanobacterial primary endosymbiosis that occurred in the common ancestor of the supergroup Archaeplastida that comprises the Viridiplantae (green algae and plants), red algae, and glaucophyte algae. These lineages include critical primary producers of freshwater and terrestrial ecosystems, progenitors of which provided plastids through secondary endosymbiosis to other algae such as diatoms and dinoflagellates that are critical to marine ecosystems. Despite its broad importance and the success of algal and plant lineages, the phagotrophic origin of the plastid imposed an interesting challenge on the predatory eukaryotic ancestor of the Archaeplastida. By engulfing an oxygenic photosynthetic cell, the host lineage imposed an oxidative stress upon itself in the presence of light. Adaptations to meet this challenge were thus likely to have occurred early on during the transition from a predatory phagotroph to an obligate phototroph (or mixotroph). Modern algae have recently been shown to employ linear tetrapyrroles (bilins) to respond to oxidative stress under high light. Here we explore the early events in plastid evolution and the possible ancient roles of bilins in responding to light and oxygen. PMID:25729749

  3. Synthesis, processing and characterization of calcia-stabilized zirconia solid electrolytes for oxygen sensing applications

    SciTech Connect

    Zhou Minghua . E-mail: mzhou@nrcan.gc.ca; Ahmad, Aftab

    2006-04-13

    Precursor powders of calcia-stabilized zirconia (CSZ) solid electrolytes have been synthesized by a sol-gel method. The phase evolution of the precursor powders after thermal treatments at different temperatures were analysized by X-ray diffraction technique. Disc-shaped sensor elements were fabricated via uniaxial pressing of the calcined powders and subsequently sintered at 1650 deg. C. Scanning electron microscopy (SEM) was used to analyze the microstructure of the sintered pellets. Platinum electrodes were applied to the sintered elements to produce potentiometric/electrochemical gas sensors. The electrical response of the gas sensors to oxygen and the complex impedance of the sensors in air were measured at various temperatures. Impedance analyses indicate that the sensor cell with 15 mol% CaO has much lower resistance (the sum of bulk and grain-boundary resistance) than the sensor cell with 22 mol% CaO. This is also reflected by the EMF responses of both sensor cells to various oxygen concentrations in the testing gas. The EMF deviation from the theoretical value of the CSZ sensor cell with 22 mol% CaO was larger than that of the CSZ sensor cell with 15 mol% CaO. The corrrelations between material compositions, microstructures of the sintered pellets and the electrical properties of the sensors are discussed.

  4. Study on a phosphorescent copper(I) complex and its oxygen-sensing performances upon polystyrene and MCM-41 matrixes

    NASA Astrophysics Data System (ADS)

    Xu, Xiao-yong; Xiao, Han-ning; Xu, Yi-ming; Zhang, Ming-jun

    In this paper, we synthesize a new ligand of 1-ethyl-2-(naphthalen-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (Phen-Np-Et) and its corresponding Cu(I) complex of [Cu(Phen-Np-Et)(POP)]BF4, where POP is bis(2-(diphenylphosphanyl)phenyl) ether. The single-crystal structure, electronic nature and photophysical property of [Cu(Phen-Np-Et)(POP)]BF4 are discussed in detail. It is found that the yellow emission from [Cu(Phen-Np-Et)(POP)]BF4 owns a long excited state lifetime of 287 μs under pure N2 atmosphere. Theoretical calculation on [Cu(Phen-Np-Et)(POP)]+ suggests that the emission comes from a triplet metal-to-ligand-charge-transfer excited state. Then, [Cu(Phen-Np-Et)(POP)]BF4 are doped into two matrixes of polystyrene and MCM-41 to investigate the oxygen-sensing performance. Finally, sensitivity maxima of 9.6 and 3.6 are achieved by the composite nanofibers of [Cu(Phen-Np-Et)(POP)]BF4/polystyrene and the [Cu(Phen-Np-Et)(POP)]BF4/MCM-41, respectively. Both samples are highly sensitive toward molecular oxygen, owing to the large surface-area-to-volume ratios of nanofibrous membranes and MCM-41 matrix.

  5. Iodine-mediated etching of gold nanorods for plasmonic sensing of dissolved oxygen and salt iodine.

    PubMed

    Zhang, Zhiyang; Chen, Zhaopeng; Cheng, Fangbin; Zhang, Yaowen; Chen, Lingxin

    2016-05-10

    Here, we have carefully investigated iodine-mediated etching of gold nanorods (AuNRs) in the presence of iodate and applied this phenomenon to on-site detection of dissolved oxygen (DO). Under given conditions, the quantitative conversion of target analytes DO to iodine leads to the etching of AuNRs along the longitudinal direction with the aid of cetyltrimethylammonium. As a result, the longitudinal localized surface plasmon resonance shifts to a short wavelength. The peak-shift can be used for quantitative determination of DO and iodate by a spectrophotometer. The satisfactory results from DO detection in different water samples and iodate detection in table salt indicate the feasibility of the proposed methods. Moreover, the as-prepared colorimetric test paper would make the detection more economical and simpler. PMID:27049138

  6. The Role of Hypoxia-Inducible Factors in Oxygen Sensing by the Carotid Body

    PubMed Central

    Prabhakar, Nanduri R.

    2013-01-01

    Chronic intermittent hypoxia (IH) associated with sleep-disordered breathing is an important cause of hypertension, which results from carotid body-mediated activation of the sympathetic nervous system. IH triggers increased levels of reactive oxygen species (ROS) in the carotid body, which induce increased synthesis and stability of hypoxia-inducible factor 1α (HIF-1α) and calpain-dependent degradation of HIF-2α. HIF-1 activates transcription of the Nox2 gene, encoding NADPH oxidase 2, which generates superoxide. Loss of HIF-2 activity leads to decreased transcription of the Sod2 gene, encoding manganese superoxide dismutase, which converts superoxide to hydrogen peroxide. Thus, IH disrupts the balance between HIF-1-dependent pro-oxidant and HIF-2-dependent anti-oxidant activities, and this loss of redox homeostasis underlies the pathogenesis of autonomic morbidities associated with IH. PMID:23080136

  7. Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III; Po Zhang

    2005-10-01

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we immobilized the potassium salt of a molybdenum cluster, K{sub 2}M{sub 6}Cl{sub 14}, in a sol-gel matrix and showed that the luminescence is stable after 54 hours at 200 C, but the quenching ratios were low and the films delaminated after thermal cycling due to densification of the matrix. Three new approaches to solve decreased quenching over time and delamination of films off fiber tips were investigated. In the first approach K{sub 2}Mo{sub 6}Cl{sub 14} embedded in cured sol-gel particles were incorporated into a TEOS based sol-gel. These gave enhanced quenching (6x), but delaminated. Our second approach was to use a commercial cyanoacrylate glue to immobilize the particles onto the tip of an optical fiber. This gave better adhesion and good quenching initially, but eventually the glue degraded upon heating. Our third approach was to use a 55% OtMOS/ TEOS sol-gel binder. Films based on this new sol-gel binder show high quenching ({approx}6x) and superior mechanical stability even after thermal cycling. Sensor measurements on an optical fiber containing K{sub 2}Mo{sub 6}Cl{sub 14} embedded in cured sol-gel particles were obtained from 100 to 25 C. The signal intensity in nitrogen was stable at 2.8 {+-} 0.2 nW, and the quenching ratio (ratio of signal in N{sub 2} vs. 21 % O{sub 2}) varied from 4.4 to 6.9X. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.

  8. Hyperbaric oxygen therapy in the management of severe acute anaemia in a Jehovah's witness.

    PubMed

    McLoughlin, P L; Cope, T M; Harrison, J C

    1999-09-01

    A case is described in which a Jehovah's Witness patient who refused blood transfusion suffered massive antepartum haemorrhage, her haemoglobin falling as low as 2.0 g.dl(-1). She was treated on an intensive care unit with intermittent positive pressure ventilation and general supportive measures, pulsed hyperbaric oxygen therapy and recombinant human erythropoietin. PMID:10460565

  9. 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

  10. Massive Systemic Air Embolism during Extracorporeal Membrane Oxygenation Support of a Neonate with Acute Respiratory Distress Syndrome after Cardiac Surgery

    PubMed Central

    Timpa, Joseph G.; O’Meara, Carlisle; McILwain, R. Britt; Dabal, Robert J.; Alten, Jeffrey A.

    2011-01-01

    Abstract: Extracorporeal membrane oxygenation (ECMO) is universally accepted as a potential lifesaving therapy for neonates suffering severe cardiorespiratory failure, with survival reported as 81% weaning off ECMO and 69% to hospital discharge in this population. Although ECMO may reduce mortality in certain neonatal patients, it is associated with significant complications. Air in the circuit complicates 4.9% of neonatal ECMO runs, and it is crucial that all ECMO caregivers are trained in the prevention of air embolism and possess the knowledge necessary to efficiently identify and remove air from the ECMO circuit to prevent life threatening consequences. We present a fatal case of neonatal systemic air embolism leading to massive entrainment of air into the ECMO venous return cannula of a neonatal patient with acute respiratory distress syndrome following repair of obstructed total anomalous pulmonary venous connection. We describe the pathophysiology and presentation of this rare condition and the importance of early recognition, due to its high mortality rate. PMID:21848179

  11. Venovenous extracorporeal membrane oxygenation for acute respiratory failure : A clinical review from an international group of experts.

    PubMed

    Fan, Eddy; Gattinoni, Luciano; Combes, Alain; Schmidt, Matthieu; Peek, Giles; Brodie, Dan; Muller, Thomas; Morelli, Andrea; Ranieri, V Marco; Pesenti, Antonio; Brochard, Laurent; Hodgson, Carol; Van Kiersbilck, Cecile; Roch, Antoine; Quintel, Michael; Papazian, Laurent

    2016-05-01

    Despite expensive life-sustaining interventions delivered in the ICU, mortality and morbidity in patients with acute respiratory failure (ARF) remain unacceptably high. Extracorporeal membrane oxygenation (ECMO) has emerged as a promising intervention that may provide more efficacious supportive care to these patients. Improvements in technology have made ECMO safer and easier to use, allowing for the potential of more widespread application in patients with ARF. A greater appreciation of the complications associated with the placement of an artificial airway and mechanical ventilation has led clinicians and researchers to seek viable alternatives to providing supportive care in these patients. Thus, this review will summarize the current knowledge regarding the use of venovenous (VV)-ECMO for ARF and describe some of the recent controversies in the field, such as mechanical ventilation, anticoagulation and transfusion therapy, and ethical concerns in patients supported with VV-ECMO. PMID:27007108

  12. Unconventional ratiometric-enhanced optical sensing of oxygen by mixed-phase TiO2

    NASA Astrophysics Data System (ADS)

    Lettieri, S.; Pallotti, D. K.; Gesuele, F.; Maddalena, P.

    2016-07-01

    We show that mixed-phase titanium dioxide (TiO2) can be effectively employed as an unconventional, inorganic, dual-emitting, and ratiometric optical sensor of O2. Simultaneous availability of rutile and anatase TiO2 photoluminescence (PL) and their peculiar "anti-correlated" PL responses to O2 allow using their ratio as a measurement parameter associated with the O2 concentration, leading to an experimental responsivity being by construction larger than the one obtainable for single-phase PL detection. A proof of this concept is given, showing a two-fold enhancement of the optical responsivity provided by the ratiometric approach. Besides the peculiar ratiometric-enhanced responsivity, other characteristics of mixed phase TiO2 can be envisaged as favorable for O2 optical probing, namely (a) low production costs, (b) absence of heterogeneous components, and (c) self-supporting properties. These characteristics encourage experimenting with its use for applications requiring high indicator quantities at a competitive price, possibly also tackling the need to develop supporting matrixes that carry the luminescent probes and avoiding issues related to the use of different components for ratiometric sensing.

  13. Omeprazole does not Potentiate Acute Oxygen Toxicity in Fetal Human Pulmonary Microvascular Endothelial Cells Exposed to Hyperoxia

    PubMed Central

    Patel, Ananddeep; Zhang, Shaojie; Moorthy, Bhagavatula; Shivanna, Binoy

    2015-01-01

    Hyperoxia contributes to the pathogenesis of broncho-pulmonary dysplasia (BPD), which is a developmental lung disease of premature infants that is characterized by an interruption of lung alveolar and pulmonary vascular development. Omeprazole (OM) is a proton pump inhibitor that is used to treat humans with gastric acid related disorders. Earlier we observed that OM-mediated aryl hydrocarbon receptor (AhR) activation attenuates acute hyperoxic lung injury in adult mice and oxygen toxicity in adult human lung cells. However, our later studies in newborn mice demonstrated that OM potentiates hyperoxia-induced developmental lung injury. Whether OM exerts a similar toxicity in primary human fetal lung cells is unknown. Hence, we tested the hypothesis that OM potentiates hyperoxia-induced cytotoxicity and ROS generation in the human fetal lung derived primary human pulmonary microvascular endothelial cells (HPMEC). OM activated AhR as evident by a dose-dependent increase in cytochrome P450 (CYP) 1A1 mRNA levels in OM-treated cells. Furthermore, OM at a concentration of 100 μM (OM 100) increased NADP(H) quinone oxidoreductase 1 (NQO1) expression. Surprisingly, hyperoxia decreased rather than increase the NQO1 protein levels in OM 100-treated cells. Exposure to hyperoxia increased cytotoxicity and hydrogen peroxide (H2O2) levels. Interestingly, OM 100-treated cells exposed to air had increased H2O2 levels. However, hyperoxia did not further augment H2O2 levels in OM 100-treated cells. Additionally, hyperoxia-mediated oxygen toxicity was similar in both vehicle- and OM-treated cells. These findings contradict our hypothesis and support the hypothesis that OM does not potentiate acute hyperoxic injury in HPMEC in vitro. PMID:26779382

  14. FIBER OPTICAL MICRO-DETECTORS FOR OXYGEN SENSING IN POWER PLANTS

    SciTech Connect

    Gregory L. Baker; Ruby N. Ghosh; D.J. Osborn III

    2004-04-01

    A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. The luminescence of Mo{sub 6}Cl{sub 12} immobilized in a sol-gel matrix was measured as a function of heater temperature up to 200 C, in an inert environment. While the luminescence decreased with temperature, the integrated intensity at 200 C should be sufficient to enable detection of the luminescence in a fiber geometry. Previously we found that aging Mo{sub 6}Cl{sub 12} at temperatures above 250 C converts the canary yellow Mo{sub 6}Cl{sub 12} to a non-luminescent gray solid. Optical and thermal aging experiments show that the alkali metal salts of Mo{sub 6}Cl{sub 12} have higher thermal stabilities and remain luminescent after aging at 280 C.

  15. Arabidopsis CAP1-mediated ammonium sensing required reactive oxygen species in plant cell growth.

    PubMed

    Bai, Ling; Zhou, Yun; Ma, Xiaonan; Gao, Lijie; Song, Chun-Peng

    2014-06-18

    [Ca (2+)]cyt-associated protein kinase (CAP) gene 1 is a receptor-like kinase that belongs to CrRLK1L (Catharanthus roseus Receptor like kinase) subfamily. CAP1 has been identified as a novel modulator of NH 4(+) in the tonoplast, which regulates root hair growth by maintaining the cytoplasmic Ca (2+) gradients. Different expression pattern of tonoplast intrinsic protein (TIP2;3) in the CAP1 knock out mutant and wild type on Murashige and Skoog (MS) medium suggested that CAP1 influences transport activity to regulate the compartmentalization of NH 4(+) into vacuole. Lower expression level of Oxidative Signal-Inducible1(OXI1) in the cap1-1 root and the abnormal reactive oxygen species (ROS) gradient in root hair of cap1-1 on MS medium indicated that ROS signaling involve in CAP1-regulated root hair growth. Wild-type-like ROS distribution pattern in the cap1-1 root hair can be reestablished in seedlings grown on NH 4(+) deficient medium, which indicated that CAP1 functions as a sensor for NH 4(+) signaling in maintaining tip-focused ROS gradient in root hairs polar growth. PMID:24940875

  16. Oxygen sensing glucose biosensors based on alginate nano-micro systems

    NASA Astrophysics Data System (ADS)

    Chaudhari, Rashmi; Joshi, Abhijeet; Srivastava, Rohit

    2014-04-01

    Clinically glucose monitoring in diabetes management is done by point-measurement. However, an accurate, continuous glucose monitoring, and minimally invasive method is desirable. The research aims at developing fluorescence-mediated glucose detecting biosensors based on near-infrared radiation (NIR) oxygen sensitive dyes. Biosensors based on Glucose oxidase (GOx)-Rudpp loaded alginate microspheres (GRAM) and GOx-Platinum-octaethylporphyrin (PtOEP)-PLAalginate microsphere system (GPAM) were developed using air-driven atomization and characterized using optical microscopy, CLSM, fluorescence spectro-photometry etc. Biosensing studies were performed by exposing standard solutions of glucose. Uniform sized GRAM and GPAM with size 50+/-10μm were formed using atomization. CLSM imaging of biosensors suggests that Rudpp and PtOEP nanoparticles are uniformly distributed in alginate microspheres. The GRAM and GPAM showed a good regression constant of 0.974 and of 0.9648 over a range of 0-10 mM of glucose with a high sensitivity of 3.349%/mM (625 nm) and 2.38%/mM (645 nm) at 10 mM of glucose for GRAM and GPAM biosensor. GRAM and GPAM biosensors show great potential in development of an accurate and minimally invasive glucose biosensor. NIR dye based assays can aid sensitive, minimally-invasive and interference-free detection of glucose in diabetic patients.

  17. Regulation of gene expression and secretory functions in oxygen-sensing pheochromocytoma cells.

    PubMed

    Conforti, L; Kobayashi, S; Beitner-Johnson, D; Conrad, P W; Freeman, T; Millhorn, D E

    1999-04-01

    The cellular response to hypoxia is complex. Specialized oxygen chemosensitive cells that are excitable respond to reduced O2 by membrane depolarization, altered gene expression, and neurotransmitter secretion. We have used the O2-sensitive pheochromocytoma (PC12) cell line to investigate the cellular response to hypoxia. Here, we present evidence that membrane depolarization and increased intracellular free Ca2+ are major regulatory events in these cells. Membrane depolarization is mediated by the inhibition of a slow-inactivating voltage-dependent potassium (K) channel. Evidence from molecular biology and patch-clamp studies indicate that the O2-sensitive K channel is a member of the Kv1 family. We also reviewed findings on the regulation of gene expression in PC12 cells during hypoxia. An increase in intracellular free Ca2+ is required for hypoxia-induced transcription of a number of genes including tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of catecholamine neurotransmitters, and several of the immediate early genes. We also reviewed the role of dopamine (DA) and adenosine (ADO) receptors in regulation of membrane depolarization and gene expression. PMID:10385038

  18. Defective Tibetan PHD2 Binding to p23 Links High Altitude Adaption to Altered Oxygen Sensing*

    PubMed Central

    Song, Daisheng; Li, Lin-sheng; Arsenault, Patrick R.; Tan, Qiulin; Bigham, Abigail W.; Heaton-Johnson, Katherine J.; Master, Stephen R.; Lee, Frank S.

    2014-01-01

    The Tibetan population has adapted to the chronic hypoxia of high altitude. Tibetans bear a genetic signature in the prolyl hydroxylase domain protein 2 (PHD2/EGLN1) gene, which encodes for the central oxygen sensor of the hypoxia-inducible factor (HIF) pathway. Recent studies have focused attention on two nonsynonymous coding region substitutions, D4E and C127S, both of which are markedly enriched in the Tibetan population. These amino acids reside in a region of PHD2 that harbors a zinc finger, which we have previously discovered binds to a Pro-Xaa-Leu-Glu (PXLE) motif in the HSP90 cochaperone p23, thereby recruiting PHD2 to the HSP90 pathway to facilitate HIF-α hydroxylation. We herein report that the Tibetan PHD2 haplotype (D4E/C127S) strikingly diminishes the interaction of PHD2 with p23, resulting in impaired PHD2 down-regulation of the HIF pathway. The defective binding to p23 depends on both the D4E and C127S substitutions. We also identify a PXLE motif in HSP90 itself that can mediate binding to PHD2 but find that this interaction is maintained with the D4E/C127S PHD2 haplotype. We propose that the Tibetan PHD2 variant is a loss of function (hypomorphic) allele, leading to augmented HIF activation to facilitate adaptation to high altitude. PMID:24711448

  19. Acute EPOC response in women to circuit training and treadmill exercise of matched oxygen consumption.

    PubMed

    Braun, W A; Hawthorne, W E; Markofski, M M

    2005-08-01

    The purpose of the study was to evaluate the effects of circuit training (CT) and treadmill exercise performed at matched rates of oxygen consumption and exercise duration on elevated post-exercise oxygen consumption (EPOC) in untrained women, while controlling for the menstrual cycle. Eight, untrained females (31.3 +/- 9.1 years; 2.04 +/- 0.26 l min(-1) estimated VO2max; BMI=24.6+/-3.9 kg/m2) volunteered to participate in the study. Testing was performed during the early follicular phase for each subject to minimize hormonal variability between tests. Subjects performed two exercise sessions approximately 28 days apart. Resting, supine energy expenditure was measured for 30 min preceding exercise and for 1 h after completion of exercise. Respiratory gas exchange data were collected continuously during rest and exercise periods via indirect calorimetry. CT consisted of three sets of eight common resistance exercises. Pre-exercise and exercise oxygen consumption was not different between testing days (P>0.05). Thus, exercise conditions were appropriately matched. Analysis of EPOC data revealed that CT resulted in a significantly higher (p<0.05) oxygen uptake during the first 30 min of recovery (0.27 +/- 0.01 l min(-1) vs 0.23+/-0.01 l min(-1)); though, at 60 min, treatment differences were not present. Mean VO2 remained significantly higher (0.231 +/- 0.01 l min(-1)) than pre-exercise measures (0.193 +/- 0.01 l min(-1)) throughout the 60-min EPOC period (p<0.05). Heart rate, RPE, V(E) and RER were all significantly greater during CT (p<0.05). When exercise VO2 and exercise duration were matched, CT was associated with a greater metabolic disturbance and cost during the early phases of EPOC. PMID:15942765

  20. Effects of acute hypoxia on the oxygen uptake kinetics of older adults during cycling exercise.

    PubMed

    Zerbini, Livio; Brighenti, Alfredo; Pellegrini, Barbara; Bortolan, Lorenzo; Antonetti, Tommaso; Schena, Federico

    2012-08-01

    Pulmonary oxygen uptake, heart rate (HR), and deoxyhemoglobin (HHb) kinetics were studied in a group of older adults exercising in hypoxic conditions. Fourteen healthy older adults (aged 66 ± 6 years) performed 4 exercise sessions that consisted of (i) an incremental test to exhaustion on a cycloergometer while breathing normoxic room air (fractional inspired oxygen (FiO(2)) = 20.9% O(2)); (ii) an incremental test to exhaustion on a cycloergometer while breathing hypoxic room air (FiO(2) = 15% O(2)); (iii) 3 repeated square wave cycling exercises at moderate intensity while breathing normoxic room air; and (iv) 3 repeated square wave cycling exercises at moderate intensity while breathing hypoxic room air. During all exercise sessions, pulmonary gas exchange was measured breath-by-breath; HHb was determined on the vastus lateralis muscle by near-infrared spectroscopy; and HR was collected beat-by-beat. The pulomary oxygen uptake kinetics became slower in hypoxia (31 ± 9 s) than in normoxia (27 ± 7 s) because of an increased mismatching between O(2) delivery to O(2) utilization at the level of the muscle. The HR and HHb kinetics did not change between hypoxia and normoxia. PMID:22680339

  1. Extracorporeal membrane oxygenation improves survival in a novel 24-hour pig model of severe acute respiratory distress syndrome.

    PubMed

    Araos, Joaquín; Alegría, Leyla; García, Patricio; Damiani, Felipe; Tapia, Pablo; Soto, Dagoberto; Salomon, Tatiana; Rodriguez, Felipe; Amthauer, Macarena; Erranz, Benjamín; Castro, Gabriel; Carreño, Pamela; Medina, Tania; Retamal, Jaime; Cruces, Pablo; Bugedo, Guillermo; Bruhn, Alejandro

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) is increasingly being used to treat severe acute respiratory distress syndrome (ARDS). However, there is limited clinical evidence about how to optimize the technique. Experimental research can provide an alternative to fill the actual knowledge gap. The purpose of the present study was to develop and validate an animal model of acute lung injury (ALI) which resembled severe ARDS, and which could be successfully supported with ECMO. Eighteen pigs were randomly allocated into three groups: sham, ALI, and ALI + ECMO. ALI was induced by a double-hit consisting in repeated saline lavage followed by a 2-hour period of injurious ventilation. All animals were followed up to 24 hours while being ventilated with conventional ventilation (tidal volume 10 ml/kg). The lung injury model resulted in severe hypoxemia, increased airway pressures, pulmonary hypertension, and altered alveolar membrane barrier function, as indicated by an increased protein concentration in bronchoalveolar fluid, and increased wet/dry lung weight ratio. Histologic examination revealed severe diffuse alveolar damage, characteristic of ARDS. Veno-venous ECMO was started at the end of lung injury induction with a flow > 60 ml/kg/min resulting in rapid reversal of hypoxemia and pulmonary hypertension. Mortality was 0, 66.6 and 16.6% in the SHAM, ALI and ALI + ECMO groups, respectively (p < 0.05). This is a novel clinically relevant animal model that can be used to optimize the approach to ECMO and foster translational research in extracorporeal lung support. PMID:27398166

  2. Extracorporeal membrane oxygenation improves survival in a novel 24-hour pig model of severe acute respiratory distress syndrome

    PubMed Central

    Araos, Joaquín; Alegría, Leyla; García, Patricio; Damiani, Felipe; Tapia, Pablo; Soto, Dagoberto; Salomon, Tatiana; Rodriguez, Felipe; Amthauer, Macarena; Erranz, Benjamín; Castro, Gabriel; Carreño, Pamela; Medina, Tania; Retamal, Jaime; Cruces, Pablo; Bugedo, Guillermo; Bruhn, Alejandro

    2016-01-01

    Extracorporeal membrane oxygenation (ECMO) is increasingly being used to treat severe acute respiratory distress syndrome (ARDS). However, there is limited clinical evidence about how to optimize the technique. Experimental research can provide an alternative to fill the actual knowledge gap. The purpose of the present study was to develop and validate an animal model of acute lung injury (ALI) which resembled severe ARDS, and which could be successfully supported with ECMO. Eighteen pigs were randomly allocated into three groups: sham, ALI, and ALI + ECMO. ALI was induced by a double-hit consisting in repeated saline lavage followed by a 2-hour period of injurious ventilation. All animals were followed up to 24 hours while being ventilated with conventional ventilation (tidal volume 10 ml/kg). The lung injury model resulted in severe hypoxemia, increased airway pressures, pulmonary hypertension, and altered alveolar membrane barrier function, as indicated by an increased protein concentration in bronchoalveolar fluid, and increased wet/dry lung weight ratio. Histologic examination revealed severe diffuse alveolar damage, characteristic of ARDS. Veno-venous ECMO was started at the end of lung injury induction with a flow > 60 ml/kg/min resulting in rapid reversal of hypoxemia and pulmonary hypertension. Mortality was 0, 66.6 and 16.6% in the SHAM, ALI and ALI + ECMO groups, respectively (p < 0.05). This is a novel clinically relevant animal model that can be used to optimize the approach to ECMO and foster translational research in extracorporeal lung support. PMID:27398166

  3. Acute Myocardial Infarction Complicated by Cardiogenic Shock: An Algorithm-Based Extracorporeal Membrane Oxygenation Program Can Improve Clinical Outcomes.

    PubMed

    Unai, Shinya; Tanaka, Daizo; Ruggiero, Nicholas; Hirose, Hitoshi; Cavarocchi, Nicholas C

    2016-03-01

    Extracorporeal membrane oxygenation (ECMO) in our institution resulted in near total mortality prior to the establishment of an algorithm-based program in July 2010. We hypothesized that an algorithm-based ECMO program improves the outcome of patients with acute myocardial infarction complicated with cardiogenic shock. Between March 2003 and July 2013, 29 patients underwent emergent catheterization for acute myocardial infarction due to left main or proximal left anterior descending artery occlusion complicated with cardiogenic shock (defined as systolic blood pressure <90 mm Hg despite multiple inotropes, with or without intra-aortic balloon pump, lactic acidosis). Of 29 patients, 15 patients were treated before July 2010 (Group 1, old program), and 14 patients were treated after July 2010 (Group 2, new program). There were no significant differences in the baseline characteristics, including age, sex, coronary risk factors, and left ventricular ejection fraction between the two groups. Cardiopulmonary resuscitation prior to ECMO was performed in two cases (13%) in Group 1 and four cases (29%) in Group 2. ECMO support was performed in one case (6.7%) in Group 1 and six cases (43%) in Group 2. The 30-day survival of Group 1 versus Group 2 was 40 versus 79% (P = 0.03), and 1-year survival rate was 20 versus 56% (P = 0.01). The survival rate for patients who underwent ECMO was 0% in Group 1 versus 83% in Group 2 (P = 0.09). In Group 2, the mean duration on ECMO was 9.8 ± 5.9 days. Of the six patients who required ECMO in Group 2, 100% were successfully weaned off ECMO or were bridged to ventricular assist device implantation. Initiation of an algorithm-based ECMO program improved the outcomes in patients with acute myocardial infarction complicated by cardiogenic shock. PMID:26148217

  4. Pyruvate modifies metabolic flux and nutrient sensing during extracorporeal membrane oxygenation in an immature swine model

    SciTech Connect

    Ledee, Dolena R.; Kajimoto, Masaki; O'Kelly-Priddy, Colleen M.; Olson, Aaron; Isern, Nancy G.; Robillard Frayne, Isabelle; Des Rosiers, Christine; Portman, Michael A.

    2015-07-01

    Extracorporeal membrane oxygenation (ECMO) provides mechanical circulatory support for infants and children with postoperative cardiopulmonary failure. Nutritional support is mandatory during ECMO, although specific actions for substrates on the heart have not been delineated. Prior work shows that enhancing pyruvate oxidation promotes successful weaning from ECMO. Accordingly, we closely examined the role of prolonged systemic pyruvate supplementation in modifying metabolic parameters during the unique conditions of ventricular unloading provided by ECMO. Twelve male mixed breed Yorkshire piglets (age 30-49 days) received systemic infusion of either normal saline (Group C) or pyruvate (Group P) during ECMO for 8 hours. Over the final hour piglets received [2-13C] pyruvate, and [13C6]-L-leucine, as an indicator for oxidation and protein synthesis. A significant increase in lactate and pyruvate concentrations occurred, along with an increase in the absolute concentration of all measured CAC intermediates. Group P showed greater anaplerotic flux through pyruvate carboxylation although pyruvate oxidation relative to citrate synthase flux was similar to Group C. The groups demonstrated similar leucine fractional contributions to acetyl-CoA and fractional protein synthesis rates. Pyruvate also promoted an increase in the phosphorylation state of several nutrient sensitive enzymes, such as AMPK and ACC, and promoted O-GlcNAcylation through the hexosamine biosynthetic pathway (HBP). In conclusion, prolonged pyruvate supplementation during ECMO modified anaplerotic pyruvate flux and elicited changes in important nutrient and energy sensitive pathways, while preserving protein synthesis. Therefore, the observed results support the further study of nutritional supplementation and its downstream effects on cardiac adaptation during ventricular unloading.

  5. Pyruvate modifies metabolic flux and nutrient sensing during extracorporeal membrane oxygenation in an immature swine model

    PubMed Central

    Ledee, Dolena R.; Kajimoto, Masaki; O'Kelly Priddy, Colleen M.; Olson, Aaron K.; Isern, Nancy; Robillard-Frayne, Isabelle; Des Rosiers, Christine

    2015-01-01

    Extracorporeal membrane oxygenation (ECMO) provides mechanical circulatory support for infants and children with postoperative cardiopulmonary failure. Nutritional support is mandatory during ECMO although specific actions for substrates on the heart have not been delineated. Prior work shows that enhancing pyruvate oxidation promotes successful weaning from ECMO. Accordingly, we tested the hypothesis that prolonged systemic pyruvate supplementation activates pyruvate oxidation in an immature swine model in vivo. Twelve male mixed-breed Yorkshire piglets (age 30–49 days) received systemic infusion of either normal saline (group C) or pyruvate (group P) during the final 6 h of 8 h of ECMO. Over the final hour, piglets received [2-13C] pyruvate, as a reference substrate for oxidation, and [13C6]-l-leucine, as an indicator for amino acid oxidation and protein synthesis. A significant increase in lactate and pyruvate concentrations occurred, along with an increase in the absolute concentration of the citric acid cycle intermediates. An increase in anaplerotic flux through pyruvate carboxylation in group P occurred compared with no change in pyruvate oxidation. Additionally, pyruvate promoted an increase in the phosphorylation state of several nutrient-sensitive enzymes, like AMP-activated protein kinase and acetyl CoA carboxylase, suggesting activation for fatty acid oxidation. Pyruvate also promoted O-GlcNAcylation through the hexosamine biosynthetic pathway. In conclusion, although prolonged pyruvate supplementation did not alter pyruvate oxidation, it did elicit changes in nutrient- and energy-sensitive pathways. Therefore, the observed results support the further study of pyruvate and its downstream effect on cardiac function. PMID:25910802

  6. Acute toxicity assessment of N,N-diethyl-m-toluamide (DEET) on the oxygen flux of the dinoflagellate Gymnodinium instriatum.

    PubMed

    Martinez, Eloy; Vélez, Sylvia M; Mayo, Marietta; Sastre, Miguel P

    2016-01-01

    Despite the ubiquitous occurrence of N,N-diethyl-m-toluamide (DEET) in aquatic systems, assessments evaluating the toxicity of DEET on phytoplankton species are summed to a single study on a unicellular green alga. In particular, the toxicological effects of DEET in dinoflagellates are unknown. In this study, we employed the mixotrophic dinoflagellate Gymnodinium instriatum as a study system to evaluate acute effects of DEET on the oxygen flux of laboratory cultures. This study reports an inhibitory reaction model of DEET described by the equation y = 4.99x(0.54), where y represents the percent inhibition of oxygen flux and x represents DEET concentration in mg L(−1) (r(2) = 0.98). Based on this model, the effective concentration of DEET needed to reduce O2 flux by 50% (EC50) for this species was found to be at 72.9 mg L(−1). The reported EC50 is more than five times lower than the EC50 reported previously for the unicellular green algae Chlorella protothecoides. This study raises the question of the potential toxicological effects of DEET in dinoflagellates, in particular those populations inhabiting systems characterized by low water circulation such as enclosed bays and lagoons. PMID:26467804

  7. Helmet CPAP versus Oxygen Therapy in Hypoxemic Acute Respiratory Failure: A Meta-Analysis of Randomized Controlled Trials

    PubMed Central

    Luo, Yuwen; Luo, Yan; Li, Yun; Zhou, Luqian; Zhu, Zhe; Chen, Yitai; Huang, Yuxia

    2016-01-01

    Purpose The efficacy of helmet continuous positive airway pressure (CPAP) in hypoxemic acute respiratory failure (hARF) remains unclear. The aim of this meta-analysis was to critically review studies that investigated the effect of helmet CPAP on gas exchange, mortality, and intubation rate in comparison with standard oxygen therapy. Materials and Methods We performed a meta-analysis of randomized controlled trials (RCTs) by searching the PubMed, Embase, Cochrane library, OVID, and CBM databases, and the bibliographies of the retrieved articles. Studies that enrolled adults with hARF who were treated with helmet CPAP and measured at least one of the following parameters were included: gas exchange, intubation rate, in-hospital mortality rate. Results Four studies with 377 subjects met the inclusion criteria and were analyzed. Compared to the standard oxygen therapy, helmet CPAP significantly increased the PaO2/FiO2 [weighted mean difference (WMD)=73.40, 95% confidence interval (95% CI): 43.92 to 102.87, p<0.00001], and decreased the arterial carbon dioxide levels (WMD=-1.92, 95% CI: -3.21 to -0.63, p=0.003), intubation rate [relative risk (RR)=0.21, 95% CI: 0.11 to 0.40, p<0.00001], and in-hospital mortality rate (RR=0.22, 95% CI: 0.09 to 0.50, p=0.0004). Conclusion The results of this meta-analysis suggest that helmet CPAP improves oxygenation and reduces mortality and intubation rates in hARF. However, the significant clinical and statistical heterogeneity of the literature implies that large RCTs are needed to determine the role of helmet CPAP in different hypoxemic ARF populations. PMID:27189288

  8. 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. PMID:27057912

  9. Heteronuclear Ir(III)-Ln(III) Luminescent Complexes: Small-Molecule Probes for Dual Modal Imaging and Oxygen Sensing.

    PubMed

    Jana, Atanu; Crowston, Bethany J; Shewring, Jonathan R; McKenzie, Luke K; Bryant, Helen E; Botchway, Stanley W; Ward, Andrew D; Amoroso, Angelo J; Baggaley, Elizabeth; Ward, Michael D

    2016-06-01

    Luminescent, mixed metal d-f complexes have the potential to be used for dual (magnetic resonance imaging (MRI) and luminescence) in vivo imaging. Here, we present dinuclear and trinuclear d-f complexes, comprising a rigid framework linking a luminescent Ir center to one (Ir·Ln) or two (Ir·Ln2) lanthanide metal centers (where Ln = Eu(III) and Gd(III), respectively). A range of physical, spectroscopic, and imaging-based properties including relaxivity arising from the Gd(III) units and the occurrence of Ir(III) → Eu(III) photoinduced energy-transfer are presented. The rigidity imposed by the ligand facilitates high relaxivities for the Gd(III) complexes, while the luminescence from the Ir(III) and Eu(III) centers provide luminescence imaging capabilities. Dinuclear (Ir·Ln) complexes performed best in cellular studies, exhibiting good solubility in aqueous solutions, low toxicity after 4 and 18 h, respectively, and punctate lysosomal staining. We also demonstrate the first example of oxygen sensing in fixed cells using the dyad Ir·Gd, via two-photon phosphorescence lifetime imaging (PLIM). PMID:27219675

  10. Impairment of Venous Drainage on Extracorporeal Membrane Oxygenation Secondary to Air Trapping in Acute Asphyxial Asthma.

    PubMed

    Niimi, Kevin S; Lewis, Leslie S; Fanning, Jeffrey J

    2015-06-01

    The inability to adequately support a patient on extracorporeal membrane oxygenation (ECMO) due to impaired drainage is not an uncommon occurrence during support. Typically, the causes include hypovolemia, kinks in the circuit, cannula malposition, or inadequate cannula size. In this report we present an uncommon etiology of this problem. A 3-year-old female presented to our hospital in status asthmaticus and pulseless electrical activity (PEA). This was a result of dynamic hyperinflation of the lungs causing physical obstruction of venous return to the heart. Upon initiating venoarterial (VA) ECMO, we experienced inadequate drainage that did not improve despite multiple interventions. This resolved with the addition of an inhaled anesthetic gas to treat this patient's severe bronchospasm. This case illustrates the importance of considering a patient's physiology or disease state and how that may affect the mechanics of ECMO support. PMID:26405359

  11. Vorinostat Induces Reactive Oxygen Species and DNA Damage in Acute Myeloid Leukemia Cells

    PubMed Central

    Pettersson, Filippa; Retrouvey, Hélène; Skoulikas, Sophia; Miller, Wilson H.

    2011-01-01

    Histone deacetylase inhibitors (HDACi) are promising anti-cancer agents, however, their mechanisms of action remain unclear. In acute myeloid leukemia (AML) cells, HDACi have been reported to arrest growth and induce apoptosis. In this study, we elucidate details of the DNA damage induced by the HDACi vorinostat in AML cells. At clinically relevant concentrations, vorinostat induces double-strand breaks and oxidative DNA damage in AML cell lines. Additionally, AML patient blasts treated with vorinostat display increased DNA damage, followed by an increase in caspase-3/7 activity and a reduction in cell viability. Vorinostat-induced DNA damage is followed by a G2-M arrest and eventually apoptosis. We found that pre-treatment with the antioxidant N-acetyl cysteine (NAC) reduces vorinostat-induced DNA double strand breaks, G2-M arrest and apoptosis. These data implicate DNA damage as an important mechanism in vorinostat-induced growth arrest and apoptosis in both AML cell lines and patient-derived blasts. This supports the continued study and development of vorinostat in AMLs that may be sensitive to DNA-damaging agents and as a combination therapy with ionizing radiation and/or other DNA damaging agents. PMID:21695163

  12. Acute effects of sustained isometric knee extension on cerebral and muscle oxygenation responses.

    PubMed

    Pereira, Marta Inez R; Gomes, Paulo Sergio C; Bhambhani, Yagesh N

    2009-07-01

    Cerebral contra-lateral frontal lobe and the dominant vastus lateralis muscle oxygenation (Cox, Mox) and blood volume (Cbv, Mbv) were recorded simultaneously using near infrared spectroscopy (NIRS) in 12 healthy volunteers (37.4 +/- 9.9 years; 72.3 +/- 16.1 kg; 171.0 +/- 9.6 cm) during 2 min resting baseline, an isometric knee extension with the 1 RM load sustained to the point of fatigue, and 3 min recovery. The mean exercise duration was 19.1 +/- 2.6 s. During the contraction, Cox and Cbv increased systematically with no sign of levelling off until the point of fatigue. In contrast, Mox and Mbv declined continuously until the termination of exercise. Qualitative analysis of these NIRS profiles suggested that maximal isometric performance under normoxic conditions was most likely not limited by central neuronal activation, but rather, was due to factors within the exercising muscle. It is likely that depletion of intramuscular stores of high energy phosphates and oxymyoglobin, as well as the accumulation of metabolites from anaerobic pathways, were implicated in fatigue during this sustained high intensity isometric contraction. PMID:19486342

  13. Outcome of veno-venous extracorporeal membrane oxygenation use in acute respiratory distress syndrome after cardiac surgery with cardiopulmonary bypass

    PubMed Central

    Song, Joo Han; Woo, Won Ki; Song, Seung Hwan; Kim, Hyo Hyun; Kim, Bong Joon; Kim, Ha Eun; Kim, Do Jung; Suh, Jee Won; Shin, Yu Rim; Park, Han Ki; Lee, Seung Hyun; Joo, Hyun Chel; Lee, Sak; Chang, Byung Chul; Yoo, Kyung Jong; Kim, Young Sam

    2016-01-01

    Background Cardiac surgery with cardiopulmonary bypass (CPB) is a known risk factor for acute respiratory distress syndrome (ARDS). We aimed to analyze the treatment outcome in patients who required veno-venous extracorporeal membrane oxygenation (VV-ECMO) for postcardiotomy ARDS despite other rescue modalities. Methods We retrospectively reviewed the outcomes in 13 patients (mean age, 54.7±5.9 years) who received VV-ECMO support for refractory ARDS after cardiac surgery between March 2013 and February 2016 at Severance Hospital, Yonsei University (Seoul, Korea). Results At the start of VV-ECMO, the average lung injury score was 3.0±0.2, and the Respiratory Extracorporeal Membrane Oxygenation Survival Prediction (RESP) score was −4±1.1. Although 7 patients initiated VV-ECMO support within 24 h from operation, the remaining 6 started at a median of 8.5 days (range, 5−16 days). Nine (69.3%) patients were successfully weaned from VV-ECMO. After a median follow-up duration of 14.5 months (range, 1.0−33.0 months) for survivors, the 1-year overall survival was 58.6%±14.4%. The differences in the overall survival from VV-ECMO according to the RESP score risk classes were borderline significant (100% in class III, 50%±25% in class IV, and 20%±17.9% in class V; P=0.088). Conclusions VV-ECMO support can be a feasible rescue strategy for adult patients who develop refractory ARDS after a cardiac surgery. Additionally, the RESP score seems a valuable prognostic tool for post-ECMO survival outcome in this patient population as well. PMID:27499972

  14. The acute effects of nicotine, tobacco smoke and carbon monoxide on myocardial oxygen tension in the anaesthetized cat

    PubMed Central

    Rink, Richard D.

    1978-01-01

    1 The acute effects of nicotine, tobacco smoke, and carbon monoxide on myocardial oxygen tension (MPo2) were estimated amperometrically in 33 anaesthetized open-chest cats with a glass-insulated 25 μm platinum cathode within a 22-gauge needle implanted in the left ventricular wall. 2 MPo2 was 1.6-60 mmHg (mean 23.5 mmHg) when arterial Po2 was >80 mmHg. Sequential intravenous infusions of nicotine (2-3 μg/kg every 45 s) or intracheal puffs (3-5 ml) of tobacco smoke commonly produced transitory increases (25-35 mmHg) of arterial pressure and 4-6 mmHg increments of MPo2. Intratracheal puffs (5 ml) of 5% carbon monoxide sufficient to increase carboxyhaemoglobin from 0.8 to 1.5% to 4-7% had no effect on arterial Po2 or blood pressure but typically decreased MPo2 by approximately 1-4 mmHg. Augmentation of MPo2 often succeeded carbon monoxide administration. 3 Arterial hypoxia (arterial Po2 < 60 mmHg) reduced mean MPo2 to 14.4 mmHg but anoxic levels were not observed. Pressor responses to nicotine and tobacco smoke were accompanied by small increases (usually 1-3 mmHg) of MPo2. Puffs of 5% carbon monoxide had less effect than during normoxia. Locations of low MPo2 (<10 mmHg) were unaffected as carboxyhaemoglobin was raised to 7-11% during hypoxaemia. 4 It is concluded that nicotine and tobacco smoke cause augmentation of myocardial oxygen supply, even during moderate hypoxaemia. By contrast, smoking dosages of carbon monoxide have the potential of producing a small reduction of MPo2 during normoxia, but the effect is negligible during moderate hypoxaemia. PMID:656704

  15. Cognitive functions and cerebral oxygenation changes during acute and prolonged hypoxic exposure.

    PubMed

    Davranche, Karen; Casini, Laurence; Arnal, Pierrick J; Rupp, Thomas; Perrey, Stéphane; Verges, Samuel

    2016-10-01

    The present study aimed to assess specific cognitive processes (cognitive control and time perception) and hemodynamic correlates using functional near-infrared spectroscopy (fNIRS) during acute and prolonged high-altitude exposure. Eleven male subjects were transported via helicopter and dropped at 14 272 ft (4 350 meters) of altitude where they stayed for 4 days. Cognitive tasks, involving a conflict task and temporal bisection task, were performed at sea level the week before ascending to high altitude, the day of arrival (D0), the second (D2) and fourth (D4) day at high altitude. Cortical hemodynamic changes in the prefrontal cortex (PFC) area were monitored with fNIRS at rest and during the conflict task. Results showed that high altitude impacts information processing in terms of speed and accuracy. In the early hours of exposure (D0), participants displayed slower reaction times (RT) and decision errors were twice as high. While error rate for simple spontaneous responses remained twice that at sea level, the slow-down of RT was not detectable after 2 days at high-altitude. The larger fNIRS responses from D0 to D2 suggest that higher prefrontal activity partially counteracted cognitive performance decrements. Cognitive control, assessed through the build-up of a top-down response suppression mechanism, the early automatic response activation and the post-error adjustment were not impacted by hypoxia. However, during prolonged hypoxic exposure the temporal judgments were underestimated suggesting a slowdown of the internal clock. A decrease in cortical arousal level induced by hypoxia could consistently explain both the slowdown of the internal clock and the persistence of a higher number of errors after several days of exposure. PMID:27262217

  16. Extracorporeal Membrane Oxygenation as Bridge-to-Decision in Acute Heart Failure due to Systemic Light-Chain Amyloidosis

    PubMed Central

    Silva, Jennifer Mancio; Fontes-Carvalho, Ricardo; Valente, Dília; Almeida, Cristiana; Cruz, António José; Tente, David; Coelho, Henrique; Oliveira, Marco; Albuquerque, Aníbal; Ribeiro, Vasco Gama

    2015-01-01

    Patient: Female, 58 Final Diagnosis: Acute hear failure Symptoms: Dispnoea • edema • fatigue Medication: — Clinical Procedure: Bone marrow biopsy • endomyocardial biopsy • abdominal subcutaneous fat biopsy under ECMO support Specialty: Cardiology Objective: Rare disease Background: Cardiac amyloidosis results from the amyloid deposition in heart tissue, either in the context of a systemic disease or as a localized form. Several pro-amyloid proteins can produce amyloid deposits in the heart. Each of these amyloidoses has characteristic clinical (cardiac and extracardiac) features, and a specific diagnosis and treatment. Case Report: A 58-year-old woman who presented with acute heart failure and echocardiographic findings strongly suggestive of infiltrative cardiomyopathy needed percutaneous veno-arterial extracorporeal membrane oxygenation (ECMO) as bridge-to-decision. Amyloid deposition was found on endomyocardial and bone marrow biopsies. Bone marrow plasma cell infiltrate with acute renal lesion and hypercalcemia confirmed the diagnosis of multiple myeloma-associated systemic light-chain amyloidosis (AL). Refractory shock with multi-organic failure syndrome persisted and no improvements in left ventricular function and structure were seen. After extensive discussion by a multidisciplinary team, and with the patients’ family, she was not considered eligible for high-dose chemotherapy and/or autologous stem cell transplantation, heart transplantation, or sequential heart with autologous stem cell transplantation. The patient died a few hours after ECMO withdrawal. During the 14 days of ECMO support no major bleeding or thrombotic complications occurred. Conclusions: The clinician must consider a diagnosis of cardiac amyloidosis in patients with heart failure, a restrictive type of cardiomyopathy with ventricular hypertrophy in the absence of valve abnormalities, or uncontrolled arterial hypertension. Although developments in chemotherapy have greatly

  17. High-sensitivity extended-gate field-effect transistors as pH sensors with oxygen-modified reduced graphene oxide films coated on different reverse-pyramid silicon structures as sensing heads

    NASA Astrophysics Data System (ADS)

    Li, Yu-Ren; Chang, Shih-hsueh; Chang, Chia-Tsung; Tsai, Wan-Lin; Chiu, Yu-Kai; Yang, Po-Yu; Cheng, Huang-Chung

    2016-04-01

    A high-performance extended-gate field-effect transistor (EGFET) as pH sensor with its microstructured sensing head composed of an oxygen-modified reduced graphene oxide film (RGOF) on a reverse-pyramid (RP) Si structure was developed to achieve a high sensitivity of 57.5 mV/pH with an excellent linearity of 0.9929 in a wide pH sensing range of 1-13. These features were ascribed to the large amount of sensing sites and large sensing area. In contrast, the planar Si substrate with the oxygen-plasma-treated RGOF (OPT-RGOF) at the optimal bias power showed a sensitivity of 52.9 mV/pH compared with 45.0 mV/pH for that without plasma treatment. It reveals that oxygen plasma can produce oxygen-containing groups as sensing sites, enhancing proton sensing characteristics. However, oxygen plasma treatment at high bias powers would cause damage to the RGOFs, resulting in poor conducting and sensing properties. On the other hand, the use of the RP structures could increase the effective sensing area and further promote the sensing performance.

  18. The SOS Pilot Study: A RCT of Routine Oxygen Supplementation Early after Acute Stroke—Effect on Recovery of Neurological Function at One Week

    PubMed Central

    Roffe, Christine; Ali, Khalid; Warusevitane, Anushka; Sills, Sheila; Pountain, Sarah; Allen, Martin; Hodsoll, John; Lally, Frank; Jones, Peter; Crome, Peter

    2011-01-01

    Mild hypoxia is common after stroke and associated with poor long-term outcome. Oxygen supplementation could prevent hypoxia and improve recovery. A previous study of routine oxygen supplementation showed no significant benefit at 7 and 12 months. This pilot study reports the effects of routine oxygen supplementation for 72 hours on oxygen saturation and neurological outcomes at 1 week after a stroke. Methods Patients with a clinical diagnosis of acute stroke were recruited within 24 h of hospital admission between October 2004 and April 2008. Participants were randomized to oxygen via nasal cannulae (72 h) or control (room air, oxygen given only if clinically indicated). Clinical outcomes were assessed by research team members at 1 week. Baseline data for oxygen (n = 148) and control (n = 141) did not differ between groups. Results The median (interquartile range) National Institutes of Health Stroke Scale (NIHSS) score for the groups at baseline was 6 (7) and 5 (7) respectively. The median Nocturnal Oxygen Saturation during treatment was 1.4% (0.3) higher in the oxygen than in the control group (p<0.001) during the intervention. At 1 week, the median NIHSS score had reduced by 2 (3) in the oxygen and by 1 (2) in the control group. 31% of participants in the oxygen group and 14% in the control group had an improvement of ≥4 NIHSS points at 1 week doubling the odds of improvement in the oxygen group (OR: 2.9). Conclusion Our data show that routine oxygen supplementation started within 24 hours of hospital admission with acute stroke led to a small, but statistically significant, improvement in neurological recovery at 1 week. However, the difference in NIHSS improvement may be due to baseline imbalance in stroke severity between the two groups and needs to be confirmed in a larger study and linked to longer-term clinical outcome. Trial Registration Controlled-Trials.com ISRCTN12362720; European Clinical Trials Database 2004-001866-41 PMID:21625533

  19. Acute supplementation of N-acetylcysteine does not affect muscle blood flow and oxygenation characteristics during handgrip exercise.

    PubMed

    Smith, Joshua R; Broxterman, Ryan M; Ade, Carl J; Evans, Kara K; Kurti, Stephanie P; Hammer, Shane M; Barstow, Thomas J; Harms, Craig A

    2016-04-01

    N-acetylcysteine (NAC; antioxidant and thiol donor) supplementation has improved exercise performance and delayed fatigue, but the underlying mechanisms are unknown. One possibility isNACsupplementation increases limb blood flow during severe-intensity exercise. The purpose was to determine ifNACsupplementation affected exercising arm blood flow and muscle oxygenation characteristics. We hypothesized thatNACwould lead to higher limb blood flow and lower muscle deoxygenation characteristics during severe-intensity exercise. Eight healthy nonendurance trained men (21.8 ± 1.2 years) were recruited and completed two constant power handgrip exercise tests at 80% peak power until exhaustion. Subjects orally consumed either placebo (PLA) orNAC(70 mg/kg) 60 min prior to handgrip exercise. Immediately prior to exercise, venous blood samples were collected for determination of plasma redox balance. Brachial artery blood flow (BABF) was measured via Doppler ultrasound and flexor digitorum superficialis oxygenation characteristics were measured via near-infrared spectroscopy. FollowingNACsupplementaiton, plasma cysteine (NAC: 47.2 ± 20.3 μmol/L vs.PLA: 9.6 ± 1.2 μmol/L;P = 0.001) and total cysteine (NAC: 156.2 ± 33.9 μmol/L vs.PLA: 132.2 ± 16.3 μmol/L;P = 0.048) increased. Time to exhaustion was not significantly different (P = 0.55) betweenNAC(473.0 ± 62.1 sec) andPLA(438.7 ± 58.1 sec). RestingBABFwas not different (P = 0.79) withNAC(99.3 ± 31.1 mL/min) andPLA(108.3 ± 46.0 mL/min).BABFwas not different (P = 0.42) during exercise or at end-exercise (NAC: 413 ± 109 mL/min;PLA: 445 ± 147 mL/min). Deoxy-[hemoglobin+myoglobin] and total-[hemoglobin+myoglobin] were not significantly different (P = 0.73 andP = 0.54, respectively) at rest or during exercise between conditions. We conclude that acuteNACsupplementation does not alter oxygen delivery during exercise in men. PMID:27044854

  20. TRPV4 inhibition counteracts edema and inflammation and improves pulmonary function and oxygen saturation in chemically induced acute lung injury

    PubMed Central

    Balakrishna, Shrilatha; Song, Weifeng; Achanta, Satyanarayana; Doran, Stephen F.; Liu, Boyi; Kaelberer, Melanie M.; Yu, Zhihong; Sui, Aiwei; Cheung, Mui; Leishman, Emma; Eidam, Hilary S.; Ye, Guosen; Willette, Robert N.; Thorneloe, Kevin S.; Bradshaw, Heather B.; Matalon, Sadis

    2014-01-01

    The treatment of acute lung injury caused by exposure to reactive chemicals remains challenging because of the lack of mechanism-based therapeutic approaches. Recent studies have shown that transient receptor potential vanilloid 4 (TRPV4), an ion channel expressed in pulmonary tissues, is a crucial mediator of pressure-induced damage associated with ventilator-induced lung injury, heart failure, and infarction. Here, we examined the effects of two novel TRPV4 inhibitors in mice exposed to hydrochloric acid, mimicking acid exposure and acid aspiration injury, and to chlorine gas, a severe chemical threat with frequent exposures in domestic and occupational environments and in transportation accidents. Postexposure treatment with a TRPV4 inhibitor suppressed acid-induced pulmonary inflammation by diminishing neutrophils, macrophages, and associated chemokines and cytokines, while improving tissue pathology. These effects were recapitulated in TRPV4-deficient mice. TRPV4 inhibitors had similar anti-inflammatory effects in chlorine-exposed mice and inhibited vascular leakage, airway hyperreactivity, and increase in elastance, while improving blood oxygen saturation. In both models of lung injury we detected increased concentrations of N-acylamides, a class of endogenous TRP channel agonists. Taken together, we demonstrate that TRPV4 inhibitors are potent and efficacious countermeasures against severe chemical exposures, acting against exaggerated inflammatory responses, and protecting tissue barriers and cardiovascular function. PMID:24838754

  1. Clinical utility of high-flow nasal cannula oxygen therapy for acute respiratory failure in patients with hematological disease.

    PubMed

    Harada, Kaito; Kurosawa, Shuhei; Hino, Yutaro; Yamamoto, Keita; Sakaguchi, Masahiro; Ikegawa, Shuntaro; Hattori, Keiichro; Igarashi, Aiko; Watakabe, Kyoko; Senoo, Yasushi; Najima, Yuho; Hagino, Takeshi; Doki, Noriko; Kobayashi, Takeshi; Kakihana, Kazuhiko; Iino, Toshihiro; Sakamaki, Hisashi; Ohashi, Kazuteru

    2016-01-01

    A high-flow nasal cannula (HFNC) is a newly developed device that enables high-flow oxygen therapy for patients with serious cardiopulmonary problems, but there are few data regarding its use in patients with hematological disease. The efficacy and tolerability of HFNCs for patients who developed ARF during the treatment of various hematological diseases was evaluated. Fifty-six patients underwent HFNC therapy during the last 2 years, and the causes of ARF were mainly pneumonia (n = 37) or acute congestive heart failure (n = 7). Only 11 patients (20 %) showed a good response to HFNC therapy, and remaining 45 patients (80 %) failed to respond to the initial HFNC therapy and, therefore, underwent second-line therapy including endotracheal intubation with mechanical ventilation (n = 15), non-invasive positive pressure ventilation (n = 1), or narcotic palliation alone (n = 29). Thus, HFNC appear not to be a viable treatment option in 4 out of 5 patients in this cohort of patients with hematological disease, but it was well tolerated in most patients (96 %); no major complications except for nasal soreness (n = 2) were observed. Multivariate analysis showed that the cause of ARF (pneumonia, odds ratio 11.2, 95 % CI 1.76-71.5, p = 0.01) was the only risk factor for treatment failure. PMID:27186476

  2. TRPV4 inhibition counteracts edema and inflammation and improves pulmonary function and oxygen saturation in chemically induced acute lung injury.

    PubMed

    Balakrishna, Shrilatha; Song, Weifeng; Achanta, Satyanarayana; Doran, Stephen F; Liu, Boyi; Kaelberer, Melanie M; Yu, Zhihong; Sui, Aiwei; Cheung, Mui; Leishman, Emma; Eidam, Hilary S; Ye, Guosen; Willette, Robert N; Thorneloe, Kevin S; Bradshaw, Heather B; Matalon, Sadis; Jordt, Sven-Eric

    2014-07-15

    The treatment of acute lung injury caused by exposure to reactive chemicals remains challenging because of the lack of mechanism-based therapeutic approaches. Recent studies have shown that transient receptor potential vanilloid 4 (TRPV4), an ion channel expressed in pulmonary tissues, is a crucial mediator of pressure-induced damage associated with ventilator-induced lung injury, heart failure, and infarction. Here, we examined the effects of two novel TRPV4 inhibitors in mice exposed to hydrochloric acid, mimicking acid exposure and acid aspiration injury, and to chlorine gas, a severe chemical threat with frequent exposures in domestic and occupational environments and in transportation accidents. Postexposure treatment with a TRPV4 inhibitor suppressed acid-induced pulmonary inflammation by diminishing neutrophils, macrophages, and associated chemokines and cytokines, while improving tissue pathology. These effects were recapitulated in TRPV4-deficient mice. TRPV4 inhibitors had similar anti-inflammatory effects in chlorine-exposed mice and inhibited vascular leakage, airway hyperreactivity, and increase in elastance, while improving blood oxygen saturation. In both models of lung injury we detected increased concentrations of N-acylamides, a class of endogenous TRP channel agonists. Taken together, we demonstrate that TRPV4 inhibitors are potent and efficacious countermeasures against severe chemical exposures, acting against exaggerated inflammatory responses, and protecting tissue barriers and cardiovascular function. PMID:24838754

  3. Monochloramine-sensitive amperometric microelectrode: optimization of gold, platinum, and carbon fiber sensing materials for removal of dissolved oxygen interference

    EPA Science Inventory

    Amperometric monochloramine detection using newly fabricated gold, platinum, and carbon-fiber microsensors was investigated to optimize sensor operation and eliminate oxygen interference. Gold and platinum microsensors exhibited no oxygen interference during monochloramine measu...

  4. Protective Role of Proton-Sensing TDAG8 in Lipopolysaccharide-Induced Acute Lung Injury

    PubMed Central

    Tsurumaki, Hiroaki; Mogi, Chihiro; Aoki-Saito, Haruka; Tobo, Masayuki; Kamide, Yosuke; Yatomi, Masakiyo; Sato, Koichi; Dobashi, Kunio; Ishizuka, Tamotsu; Hisada, Takeshi; Yamada, Masanobu; Okajima, Fumikazu

    2015-01-01

    Acute lung injury is characterized by the infiltration of neutrophils into lungs and the subsequent impairment of lung function. Here we explored the role of TDAG8 in lung injury induced by lipopolysaccharide (LPS) administrated intratracheally. In this model, cytokines and chemokines released from resident macrophages are shown to cause neutrophilic inflammation in the lungs. We found that LPS treatment increased TDAG8 expression in the lungs and confirmed its expression in resident macrophages in bronchoalveolar lavage (BAL) fluids. LPS administration remarkably increased neutrophil accumulation without appreciable change in the resident macrophages, which was associated with increased penetration of blood proteins into BAL fluids, interstitial accumulation of inflammatory cells, and damage of the alveolar architecture. The LPS-induced neutrophil accumulation and the associated lung damage were enhanced in TDAG8-deficient mice as compared with those in wild-type mice. LPS also increased several mRNA and protein expressions of inflammatory cytokines and chemokines in the lungs or BAL fluids. Among these inflammatory mediators, mRNA and protein expression of KC (also known as CXCL1), a chemokine of neutrophils, were significantly enhanced by TDAG8 deficiency. We conclude that TDAG8 is a negative regulator for lung neutrophilic inflammation and injury, in part, through the inhibition of chemokine production. PMID:26690120

  5. Oxygen sensing in yeast: Evidence for the involvement of the respiratory chain in regulating the transcription of a subset of hypoxic genes

    PubMed Central

    Kwast, Kurt E.; Burke, Patricia V.; Staahl, Brett T.; Poyton, Robert O.

    1999-01-01

    Oxygen availability affects the transcription of a number of genes in nearly all organisms. Although the molecular mechanisms for sensing oxygen are not precisely known, heme is thought to play a pivotal role. Here, we address the possibility that oxygen sensing in yeast, as in mammals, involves a redox-sensitive hemoprotein. We have found that carbon monoxide (CO) completely blocks the anoxia-induced expression of two hypoxic genes, OLE1 and CYC7, partially blocks the induction of a third gene, COX5b, and has no effect on the expression of other hypoxic or aerobic genes. In addition, transition metals (Co and Ni) induce the expression of OLE1 and CYC7 in a concentration-dependent manner under aerobic conditions. These findings suggest that the redox state of an oxygen-binding hemoprotein is involved in controlling the expression of at least two hypoxic yeast genes. By using mutants deficient in each of the two major yeast CO-binding hemoproteins (cytochrome c oxidase and flavohemoglobin), respiratory inhibitors, and cob1 and ρ0 mutants, we have found that the respiratory chain is involved in the anoxic induction of these two genes and that cytochrome c oxidase is likely the hemoprotein “sensor.” Our findings also indicate that there are at least two classes of hypoxic genes in yeast (CO sensitive and CO insensitive) and imply that multiple pathways/mechanisms are involved in modulating the expression of hypoxic yeast genes. PMID:10318903

  6. Oxygen Sensing via the Ethylene Response Transcription Factor RAP2.12 Affects Plant Metabolism and Performance under Both Normoxia and Hypoxia.

    PubMed

    Paul, Melanie Verena; Iyer, Srignanakshi; Amerhauser, Carmen; Lehmann, Martin; van Dongen, Joost T; Geigenberger, Peter

    2016-09-01

    Subgroup-VII-ethylene-response-factor (ERF-VII) transcription factors are involved in the regulation of hypoxic gene expression and regulated by proteasome-mediated proteolysis via the oxygen-dependent branch of the N-end-rule pathway. While research into ERF-VII mainly focused on their role to regulate anoxic gene expression, little is known on the impact of this oxygen-sensing system in regulating plant metabolism and growth. By comparing Arabidopsis (Arabidopsis thaliana) plants overexpressing N-end-rule-sensitive and insensitive forms of the ERF-VII-factor RAP2.12, we provide evidence that oxygen-dependent RAP2.12 stability regulates central metabolic processes to sustain growth, development, and anoxic resistance of plants. (1) Under normoxia, overexpression of N-end-rule-insensitive Δ13RAP2.12 led to increased activities of fermentative enzymes and increased accumulation of fermentation products, which were accompanied by decreased adenylate energy states and starch levels, and impaired plant growth and development, indicating a role of oxygen-regulated RAP2.12 degradation to prevent aerobic fermentation. (2) In Δ13RAP2.12-overexpressing plants, decreased carbohydrate reserves also led to a decrease in anoxic resistance, which was prevented by external Suc supply. (3) Overexpression of Δ13RAP2.12 led to decreased respiration rates, changes in the levels of tricarboxylic acid cycle intermediates, and accumulation of a large number of amino acids, including Ala and γ-amino butyric acid, indicating a role of oxygen-regulated RAP2.12 abundance in controlling the flux-modus of the tricarboxylic acid cycle. (4) The increase in amino acids was accompanied by increased levels of immune-regulatory metabolites. These results show that oxygen-sensing, mediating RAP2.12 degradation is indispensable to optimize metabolic performance, plant growth, and development under both normoxic and hypoxic conditions. PMID:27372243

  7. Risk Factors for Acute Kidney Injury and In-Hospital Mortality in Patients Receiving Extracorporeal Membrane Oxygenation

    PubMed Central

    Lee, Sung Woo; Yu, Mi-yeon; Lee, Hajeong; Ahn, Shin Young; Kim, Sejoong; Chin, Ho Jun; Na, Ki Young

    2015-01-01

    Background and Objectives Although acute kidney injury (AKI) is the most frequent complication in patients receiving extracorporeal membrane oxygenation (ECMO), few studies have been conducted on the risk factors of AKI. We performed this study to identify the risk factors of AKI associated with in-hospital mortality. Methods Data from 322 adult patients receiving ECMO were analyzed. AKI and its stages were defined according to Kidney Disease Improving Global Outcomes (KDIGO) classifications. Variables within 24 h before ECMO insertion were collected and analyzed for the associations with AKI and in-hospital mortality. Results Stage 3 AKI was associated with in-hospital mortality, with a hazard ratio (HR) (95% CI) of 2.690 (1.472–4.915) compared to non-AKI (p = 0.001). The simplified acute physiology score 2 (SAPS2) and serum sodium level were also associated with in-hospital mortality, with HRs of 1.02 (1.004–1.035) per 1 score increase (p = 0.01) and 1.042 (1.014–1.070) per 1 mmol/L increase (p = 0.003). The initial pump speed of ECMO was significantly related to in-hospital mortality with a HR of 1.333 (1.020–1.742) per 1,000 rpm increase (p = 0.04). The pump speed was also associated with AKI (p = 0.02) and stage 3 AKI (p = 0.03) with ORs (95% CI) of 2.018 (1.129–3.609) and 1.576 (1.058–2.348), respectively. We also found that the red cell distribution width (RDW) above 14.1% was significantly related to stage 3 AKI. Conclusion The initial pump speed of ECMO was a significant risk factor of in-hospital mortality and AKI in patients receiving ECMO. The RDW was a risk factor of stage 3 AKI. PMID:26469793

  8. The joint effects of sulfonamides and quorum sensing inhibitors on Vibrio fischeri: Differences between the acute and chronic mixed toxicity mechanisms.

    PubMed

    Wang, Ting; Liu, Yuewei; Wang, Dali; Lin, Zhifen; An, Qingqing; Yin, Chunsheng; Liu, Yin

    2016-06-01

    Quorum sensing inhibitors (QSIs) are considered to be promising antibiotic alternatives and will be increasingly exposed to the environment together with antibiotics after their research and development process; it is therefore necessary to study the joint effects of QSIs and antibiotics. In this study, single and mixed toxicity of sulfonamide (SAs) and QSIs under acute and chronic conditions and their corresponding toxicity mechanisms were investigated. The results indicated that the acute joint effect was extremely complex, ranging from an antagonistic to synergistic response, while the chronic joint effect was primarily an antagonistic response. Using a molecular docking and regression model, we found that the acute joint effect could be determined by the hydrion's, ability to be oxidized, as well as the binding energy. The chronic joint effect was primarily an antagonistic response, which was due to the QSI competing against AHL for luxR generated by SAs, leading to negative effects of the QSI-luxR complexes on luxI. This phenomenon eventually weakened the stimulatory effect caused by SAs. Finally, the main differences between acute and chronic mixtures were analyzed: (1) The target protein was different between acute and chronic toxicity mixtures, and (2) effective concentration in acute and chronic toxicity mixtures was also different. These deep insights into mixed toxicity mechanisms will play an important role in the study of antibiotic resistance genes in response to antibiotic replacements. PMID:26897575

  9. Click-assembled, oxygen-sensing nanoconjugates for depth-resolved, near-infrared imaging in a 3D cancer model.

    PubMed

    Nichols, Alexander J; Roussakis, Emmanuel; Klein, Oliver J; Evans, Conor L

    2014-04-01

    Hypoxia is an important contributing factor to the development of drug-resistant cancer, yet few nonperturbative tools exist for studying oxygenation in tissues. While progress has been made in the development of chemical probes for optical oxygen mapping, penetration of such molecules into poorly perfused or avascular tumor regions remains problematic. A click-assembled oxygen-sensing (CAOS) nanoconjugate is reported and its properties demonstrated in an in vitro 3D spheroid cancer model. The synthesis relies on the sequential click-based ligation of poly(amidoamine)-like subunits for rapid assembly. Near-infrared confocal phosphorescence microscopy was used to demonstrate the ability of the CAOS nanoconjugates to penetrate hundreds of micrometers into spheroids within hours and to show their sensitivity to oxygen changes throughout the nodule. This proof-of-concept study demonstrates a modular approach that is readily extensible to a wide variety of oxygen and cellular sensors for depth-resolved imaging in tissue and tissue models. PMID:24590700

  10. Reactive oxygen species in peripheral blood and sputum neutrophils during bacterial and nonbacterial acute exacerbation of chronic obstructive pulmonary disease.

    PubMed

    Vaitkus, Mindaugas; Lavinskiene, Simona; Barkauskiene, Diana; Bieksiene, Kristina; Jeroch, Jolanta; Sakalauskas, Raimundas

    2013-12-01

    Chronic airway inflammation can be mediated by an enhanced neutrophil oxidative burst. However, the role of bacteria in the pathogenesis of chronic obstructive pulmonary disease (COPD) exacerbations is highly controversial. The aim of this study was to evaluate the production of reactive oxygen species (ROS) in peripheral blood and sputum neutrophils during bacterial and nonbacterial acute exacerbations of COPD (AECOPD). A total of 40 patients with AECOPD, 10 healthy nonsmokers, and 10 "healthy" smokers were enrolled into the study. Peripheral blood and sputum samples were obtained during exacerbation and after recovery. Neutrophils were isolated by high-density gradient centrifugation and magnetic separation. ROS production by neutrophils was investigated after stimulation with phorbol-myristate-acetate and Staphylococcus aureus bacteria. ROS production by neutrophils was assessed as the mean fluorescent intensity using a flow cytometer. IL-8 levels in serum and induced sputum were determinant by ELISA. Spontaneous ROS production was significantly higher in neutrophils from the patients with bacterial AECOPD as compared with nonbacterial AECOPD and stable COPD (P <0.05). ROS production stimulated with PMA and with Staphylococcus aureus was significantly higher in neutrophils isolated from the patients with bacterial AECOPD as compared with nonbacterial and stable COPD (P <0.05). The serum and induced sputum IL-8 levels were significantly increased in the patients with bacterial AECOPD than nonbacterial AECOPD, stable COPS, and "healthy" smokers and nonsmokers (P <0.05) and higher in the induced sputum as the compared with serum in all studied groups (P <0.05). Enlarge CRP level was documented during AECOPD than in all other groups (P <0.05). A markedly increased ROS production in sputum neutrophils during bacterial AECOPD shows an inflammatory response reflecting enhanced local inflammation, which can be mediated by bacterial colonization. PMID:23872721

  11. [The state of acid-alkaline balance and oxygen-transport function of blood in patients with acute carotid ischemic stroke].

    PubMed

    Zhdanova, S G; Aliev, E S; Kamchatnov, P R; Mikhaĭlova, N A

    2012-01-01

    The gas composition, acid-alkaline state of arterial and venous blood and oxygen-transport function in carotid ischemic stroke was studied in 97 patients admitted to a hospital in the first 24h after stroke. Measurements were made at admission and after 5-7 days and 21-23 days. The relative hyperoxia, which reached maximal values to the first day, was found in patients in the acute stage of ischemic stroke. The increase in partial pressure of CO2 (pCO2) and relative acidosis seen to 5-7 days represent the compensatory reaction and lead to the increase in affinity of hemoglobin to oxygen thus improving the tissue oxygenation. We found the inverse correlations between the parameters of oxygen delivery (OD) and oxygen consumption (OC) in the first day and the severity of neurological deficit assessed with the NIHSS in the 21-23 days (r = -0.42; p < 0.01 and r = -0.55; p < 0.01 for OD and OC, respectively), i.e., the decrease in oxygen delivery and consumption corresponded to the greater severity of the stroke course. PMID:23390649

  12. Highly distributed multi-point, temperature and pressure compensated, fiber optic oxygen sensors (FOxSense) for aircraft fuel tank environment and safety monitoring

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar A.; Kempen, Cornelia; Sun, Sunjian; Esterkin, Yan

    2014-09-01

    This paper describes recent progress towards the development and qualification of a highly distributed, multi-point, all optical pressure and temperature compensated, fiber optic oxygen sensor (FOxSense™) system for closed-loop monitoring and safety of the oxygen ullage environment inside fuel tanks of military and commercial aircraft. The alloptical FOxSense™ system uses a passive, multi-parameter (O2/T&P) fiber optic sensor probe with no electrical connections leading to the sensors install within the fuel tanks of an aircraft. The all optical sensor consists of an integrated multi-parameter fiber optic sensor probe that integrates a fuel insensitive fluorescence based optical oxygen optrode with built-in temperature and pressure optical optrodes for compensation of temperature and pressure variants induced in the fluorescence response of the oxygen optrode. The distributed (O2/T&P) fiber optic sensors installed in the fuel tanks of the aircraft are connected to the FOxSense optoelectronic system via a fiber optic cable conduit reaching to each fuel tank in the aircraft. A multichannel frequency-domain fiber optic sensor read-out (FOxSense™) system is used to interrogate the optical signal of all three sensors in real-time and to display the fuel tank oxygen environment suitable for aircraft status and alarm applications. Preliminary testing of the all optical fiber optic oxygen sensor have demonstrated the ability to monitor the oxygen environment inside a simulated fuel tank in the range of 0% O2 to 40% O2 concentrations, temperatures from (-) 40°C to (+) 60°C, and altitudes from 0-ft to 40,000-ft.

  13. New method of preoxygenation for orotracheal intubation in patients with hypoxaemic acute respiratory failure in the intensive care unit, non-invasive ventilation combined with apnoeic oxygenation by high flow nasal oxygen: the randomised OPTINIV study protocol

    PubMed Central

    Jaber, Samir; Molinari, Nicolas; De Jong, Audrey

    2016-01-01

    Introduction Tracheal intubation in the intensive care unit (ICU) is associated with severe life-threatening complications including severe hypoxaemia. Preoxygenation before intubation has been recommended in order to decrease such complications. Non-invasive ventilation (NIV)-assisted preoxygenation allows increased oxygen saturation during the intubation procedure, by applying a positive end-expiratory pressure (PEEP) to prevent alveolar derecruitment. However, the NIV mask has to be taken off after preoxygenation to allow the passage of the tube through the mouth. The patient with hypoxaemia does not receive oxygen during this period, at risk of major hypoxaemia. High-flow nasal cannula oxygen therapy (HFNC) has a potential for apnoeic oxygenation during the apnoea period following the preoxygenation with NIV. Whether application of HFNC combined with NIV is more effective at reducing oxygen desaturation during the intubation procedure compared with NIV alone for preoxygenation in patients with hypoxaemia in the ICU with acute respiratory failure remains to be established. Methods and analysis The HFNC combined to NIV for decreasing oxygen desaturation during the intubation procedure in patients with hypoxaemia in the ICU (OPTINIV) trial is an investigator-initiated monocentre randomised controlled two-arm trial with assessor-blinded outcome assessment. The OPTINIV trial randomises 50 patients with hypoxaemia requiring orotracheal intubation for acute respiratory failure to receive NIV (pressure support=10, PEEP=5, fractional inspired oxygen (FiO2)=100%) combined with HFNC (flow=60 L/min, FiO2=100%, interventional group) or NIV alone (reference group) for preoxygenation. The primary outcome is lowest oxygen saturation during the intubation procedure. Secondary outcomes are intubation-related complications, quality of preoxygenation and ICU mortality. Ethics and dissemination The study project has been approved by the appropriate ethics committee (CPP Sud

  14. Oxygen Deficiency Responsive Gene Expression in Chlamydomonas reinhardtii through a Copper-Sensing Signal Transduction Pathway1

    PubMed Central

    Quinn, Jeanette M.; Eriksson, Mats; Moseley, Jeffrey L.; Merchant, Sabeeha

    2002-01-01

    Chlamydomonas reinhardtii activates Cpx1, Cyc6, and Crd1, encoding, respectively, coproporphyrinogen oxidase, cytochrome c6, and a novel di-iron enzyme when transferred to oxygen-deficient growth conditions. This response is physiologically relevant because C. reinhardtii experiences these growth conditions routinely, and furthermore, one of the target genes, Crd1, is functionally required for normal growth under oxygen-depleted conditions. The same genes are activated also in response to copper-deficiency through copper-response elements that function as target sites for a transcriptional activator. The core of the copper-response element, GTAC, is required also for the hypoxic response, as is a trans-acting locus, CRR1. Mercuric ions, which antagonize the copper-deficiency response, also antagonize the oxygen-deficiency response of these target genes. Taken together, these observations suggest that the oxygen- and copper-deficiency responses share signal transduction components. Nevertheless, whereas the copper-response element is sufficient for the nutritional copper response, the oxygen-deficiency response requires, in addition, a second cis-element, indicating that the response to oxygen depletion is not identical to the nutritional copper response. The distinction between the two responses is also supported by comparative analysis of the response of the target genes, Cyc6, Cpx1, and Crd1, to copper versus oxygen deficiency. A Crr1-independent pathway for Hyd1 expression in oxygen-depleted C. reinhardtii demonstrates the existence of multiple oxygen/redox-responsive circuits in this model organism. PMID:11842150

  15. Oxygen Mapping within Healthy and Acutely Infarcted Brain Tissue in Humans Using the NMR Relaxation of Lipids: A Proof-Of-Concept Translational Study

    PubMed Central

    Magat, Julie; Joudiou, Nicolas; Peeters, André P.; Jordan, Bénédicte F.; Gallez, Bernard; Duprez, Thierry

    2015-01-01

    The clinical applicability of brain oxygenation mapping using the MOBILE (Mapping of Oxygen By Imaging Lipids relaxation Enhancement) magnetic resonance (MR) technique was assessed in the clinical setting of normal brain and of acute cerebral ischemia as a founding proof-of-concept translational study. Changes in the oxygenation level within healthy brain tissue can be detected by analyzing the spin-lattice proton relaxation (‘Global T1’ combining water and lipid protons) because of the paramagnetic properties of molecular oxygen. It was hypothesized that selective measurement of the relaxation of the lipid protons (‘Lipids T1’) would result in enhanced sensitivity of pO2 mapping because of higher solubility of oxygen in lipids than in water, and this was demonstrated in pre-clinical models using the MOBILE technique. In the present study, 12 healthy volunteers and eight patients with acute (48–72 hours) brain infarction were examined with the same clinical 3T MR system. Both Lipids R1 (R1 = 1/T1) and Global R1 were significantly different in the infarcted area and the contralateral unaffected brain tissue, with a higher statistical significance for Lipids R1 (median difference: 0.408 s-1; p<0.0001) than for Global R1 (median difference: 0.154 s-1; p = 0.027). Both Lipids R1 and Global R1 values in the unaffected contralateral brain tissue of stroke patients were not significantly different from the R1 values calculated in the brain tissue of healthy volunteers. The main limitations of the present prototypic version of the MOBILE sequence are the long acquisition time (4 min), hampering robustness of data in uncooperative patients, and a 2 mm slice thickness precluding accurate measurements in small infarcts because of partial volume averaging effects. PMID:26267901

  16. 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. PMID:27109264

  17. A method for measuring brain partial pressure of oxygen in unanesthetized unrestrained subjects: the effect of acute and chronic hypoxia on brain tissue PO2

    PubMed Central

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

    2011-01-01

    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 (PtO2) is influenced by the use of anesthesia or restraint. These factors may impact the absolute level of PtO2. In this study we present a novel fibre optic method to measure brain PtO2. This method can be used in unanesthetized, unrestrained animals, provides absolute values for PO2, has a stable calibration, does not consume oxygen and is MRI compatible. Brain PtO2 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 8 Wistar rats. It is comprised of a fiber optic probe with a tip containing material that fluoresces with an oxygen dependent lifetime. Brain PtO2 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 PtO2 and inspired O2 levels was demonstrated r2=0.98 and r2=0.99 (pre- and post-acclimatization). Hypoxia acclimatization resulted in an increase in the overall brain PtO2 by approximately 35%. This paper demonstrates the use of a novel chronically implanted fibre optic based sensor for measuring absolute PtO2. It shows a very strong linear relationship in awake animals between inspired O2 and tissue O2, and shows that there is a proportional increase in PtO2 over a range of inspired values after exposure to chronic hypoxia. PMID:20817029

  18. In vivo imaging of hemodynamics and oxygen metabolism in acute focal cerebral ischemic rats with laser speckle imaging and functional photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Deng, Zilin; Wang, Zhen; Yang, Xiaoquan; Luo, Qingming; Gong, Hui

    2012-08-01

    Stroke is a devastating disease. The changes in cerebral hemodynamics and oxygen metabolism associated with stroke play an important role in pathophysiology study. But the changes were difficult to describe with a single imaging modality. Here the changes in cerebral blood flow (CBF), cerebral blood volume (CBV), and oxygen saturation (SO2) were yielded with laser speckle imaging (LSI) and photoacoustic microscopy (PAM) during and after 3-h acute focal ischemic rats. These hemodynamic measures were further synthesized to deduce the changes in oxygen extraction fraction (OEF). The results indicate that all the hemodynamics except CBV had rapid declines within 40-min occlusion of middle cerebral artery (MCAO). CBV in arteries and veins first increased to the maximum value of 112.42±36.69% and 130.58±31.01% by 15 min MCAO; then all the hemodynamics had a persistent reduction with small fluctuations during the ischemic. When ischemia lasted for 3 h, CBF in arteries, veins decreased to 17±14.65%, 24.52±20.66%, respectively, CBV dropped to 62±18.56% and 59±18.48%. And the absolute SO2 decreased by 40.52±22.42% and 54.24±11.77%. After 180-min MCAO, the changes in hemodynamics and oxygen metabolism were also quantified. The study suggested that combining LSI and PAM provides an attractive approach for stroke detection in small animal studies.

  19. 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. PMID:24052227

  20. Ratiometric Molecular Probes Based on Dual Emission of a Blue Fluorescent Coumarin and a Red Phosphorescent Cationic Iridium(III) Complex for Intracellular Oxygen Sensing

    PubMed Central

    Yoshihara, Toshitada; Murayama, Saori; Tobita, Seiji

    2015-01-01

    Ratiometric molecular probes RP1 and RP2 consisting of a blue fluorescent coumarin and a red phosphorescent cationic iridium complex connected by a tetra- or octaproline linker, respectively, were designed and synthesized for sensing oxygen levels in living cells. These probes exhibited dual emission with good spectral separation in acetonitrile. The photorelaxation processes, including intramolecular energy transfer, were revealed by emission quantum yield and lifetime measurements. The ratios (RI=(Ip/If)) between the phosphorescence (Ip) and fluorescence (If) intensities showed excellent oxygen responses; the ratio of RI under degassed and aerated conditions (RI0/RI) was 20.3 and 19.6 for RP1 and RP2. The introduction of the cationic Ir (III) complex improved the cellular uptake efficiency compared to that of a neutral analogue with a tetraproline linker. The emission spectra of the ratiometric probes internalized into living HeLa or MCF-7 cells could be obtained using a conventional microplate reader. The complex RP2 with an octaproline linker provided ratios comparable to the ratiometric measurements obtained using a microplate reader: the ratio of the RI value of RP2 under hypoxia (2.5% O2) to that under normoxia (21% O2) was 1.5 and 1.7 for HeLa and MCF-7 cells, respectively. Thus, the intracellular oxygen levels of MCF-7 cells could be imaged by ratiometric emission measurements using the complex RP2. PMID:26066988

  1. Automated oxygen titration and weaning with FreeO2 in patients with acute exacerbation of COPD: a pilot randomized trial

    PubMed Central

    Lellouche, François; Bouchard, Pierre-Alexandre; Roberge, Maude; Simard, Serge; L’Her, Erwan; Maltais, François; Lacasse, Yves

    2016-01-01

    Introduction We developed a device (FreeO2) that automatically adjusts the oxygen flow rates based on patients’ needs, in order to limit hyperoxia and hypoxemia and to automatically wean them from oxygen. Objective The aim of this study was to evaluate the feasibility of using FreeO2 in patients hospitalized in the respiratory ward for an acute exacerbation of COPD. Methods We conducted a randomized controlled trial comparing FreeO2 vs manual oxygen titration in the respiratory ward of a university hospital. We measured the perception of appropriateness of oxygen titration and monitoring in both groups by nurses and attending physicians using a Likert scale. We evaluated the time in the target range of oxygen saturation (SpO2) as defined for each patient by the attending physician, the time with severe desaturation (SpO2 <85%), and the time with hyperoxia (SpO2 >5% above the target). We also recorded length of stay, intensive care unit admissions, and readmission rate. Fifty patients were randomized (25 patients in both groups; mean age: 72±8 years; mean forced expiratory volume in 1 second: 1.00±0.49 L; and mean initial O2 flow 2.0±1.0 L/min). Results Nurses and attending physicians felt that oxygen titration and monitoring were equally appropriate with both O2 administration systems. The percentage of time within the SpO2 target was significantly higher with FreeO2, and the time with severe desaturation and hyperoxia was significantly reduced with FreeO2. Time from study inclusion to hospital discharge was 5.8±4.4 days with FreeO2 and 8.4±6.0 days with usual oxygen administration (P=0.051). Conclusion FreeO2 was deemed as an appropriate oxygen administration system by nurses and physicians of a respiratory unit. This system maintained SpO2 at the target level better than did manual titration and reduced periods of desaturation and hyperoxia. Our results also suggest that FreeO2 has the potential to reduce the hospital length of stay. PMID:27601891

  2. Remote sensing of cloud-top pressure using reflected solar radiation in the oxygen A-band

    NASA Technical Reports Server (NTRS)

    Wu, M.-L. C.

    1985-01-01

    An algorithm has been developed for using the reflection of solar radiation in the oxygen A-band to determine cloud-top altitude. Because of multiple scattering and molecular absorption inside the cloud, the reflection of clouds is substantially modified in comparison with a mirror cloud, which is assumed to have a 100 percent reflection. To infer true cloud-top altitude, therefore, it is necessary to accurately estimate the amount of 'photon penetration'. Theoretical calculations indicate that the amount of photon penetration depends on the altitude, the scaled volume scattering coefficient, and the scaled optical thickness of the cloud. Algorithms using the reflection in the oxygen A-band to determine the cloud-top pressure have been applied to an aircraft field experiment in conjunction with CCOPE, 1981. Results of this study are very encouraging, especially for extended clouds.

  3. Rescue balloon pulmonary angioplasty under veno-arterial extracorporeal membrane oxygenation in a patient with acute exacerbation of chronic thromboembolic pulmonary hypertension.

    PubMed

    Nakamura, Makiko; Sunagawa, Osahiko; Tsuchiya, Hiroyuki; Miyara, Takafumi; Taba, Yoji; Touma, Takashi; Munakata, Hiroshi; Kugai, Tadao; Okita, Yutaka

    2015-01-01

    We describe a case of a 41-year-old woman with acute exacerbation of chronic thromboembolic pulmonary hypertension (CTEPH) complicated by rapidly progressive respiratory failure and right heart failure with cardiogenic shock. A computed tomography (CT) showed thrombi in the right main pulmonary artery and bilateral peripheral pulmonary arteries, and echocardiography showed right ventricular dilatation and tricuspid regurgitation, with an estimated pressure gradient of 80 mmHg. The patient was initially diagnosed with acute pulmonary thromboembolism, and thrombolytic therapy was administered. Her condition subsequently deteriorated, however, necessitating mechanical ventilation and veno-arterial extracorporeal membrane oxygenation (VA-ECMO). We performed emergency catheter-directed thrombectomy and thrombus aspiration. Pulmonary hypertension (PH) temporarily improved, but subsequently worsened, and the patient was diagnosed with CTEPH. Pulmonary endarterectomy (PEA) was performed. After PEA, we were unable to wean the patient off VA-ECMO, and rescue balloon pulmonary angioplasty (BPA) to the middle and inferior lobe branches of the right lung was performed. Five days after BPA, the patient was removed from VA-ECMO and on the 57th day of hospitalization, she was weaned off the ventilator. The patient was discharged after 139 days of hospitalization. Rescue BPA represents a useful intervention for improving PH and weaning off VA-ECMO in a patient with acute exacerbation of CTEPH. PMID:25742948

  4. Restrictive Fluid Resuscitation Leads to Better Oxygenation than Non-Restrictive Fluid Resuscitation in Piglets with Pulmonary or Extrapulmonary Acute Respiratory Distress Syndrome

    PubMed Central

    Ye, Shunan; Li, Qiujie; Yuan, Shiying; Shu, Huaqing; Yuan, Yin

    2015-01-01

    Background Early goal-directed therapy (EGDT) is used to reduce mortality from septic shock and could be used in early fluid resuscitation of acute respiratory distress syndrome (ARDS). The aim of the present study was to assess the effects of restrictive (RFR) and nonrestrictive fluid resuscitation (NRFR) on hemodynamics, oxygenation, pulmonary function, tissue perfusion, and inflammation in piglets with pulmonary or extrapulmonary ARDS (ARDSp and ARDSexp). Material/Methods Chinese miniature piglets (6–8 weeks; 15±1 kg) were randomly divided into 2 groups (n=12/group) for establishing ARDSp and ARDSexp models, and were further divided into 2 subgroups (n=6/subgroup) for performing RFR and NRFR. Piglets were anesthetized and hemodynamic, pulmonary, and oxygenation indicators were collected at different time points for 6 hours. The goal of EGDT was set for PiCCO parameters (mean arterial pressure (MAP), urine output and cardiac index (CI), and central venous oxygen saturation (ScvO2). Results Piglets under RFR had lower urine output compared with NRFR, as well as lower total fluid volume (P<0.05). EVLW was decreased in ARDSp+RFR and NRFR, as well as in ARDSexp+RFR, but EVLW increased in ARDSexp+NRFR (P<0.05). PaO2/FiO2 decreased in ARDSp using both methods, but was higher with RFR (P<0.05), and was increased in ARDSexp+RFR. Other pulmonary indicators were comparable. The anti-inflammatory cytokines IL-10 and LXA4 were increased in ARDSexp after RFR (P<0.05), but not in the other groups. Conclusions RFR led to better oxygenation in ARDSp and ARDSexp compared with NRFR, but fluid restriction improved oxygenation in ARDSexp only. PMID:26166324

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

    SciTech Connect

    Gundavarapu, Sravanthi; Zhuang, Jianguo; Barrett, Edward G.; Xu, Fadi; Russell, Robert G.; Sopori, Mohan L.

    2014-01-15

    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 including 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.

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

    PubMed

    Gundavarapu, Sravanthi; Zhuang, Jianguo; Barrett, Edward G; Xu, Fadi; Russell, Robert G; Sopori, Mohan L

    2014-01-15

    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 including weakened response to hypoxia. We now show that LD50 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 24h; however, many animals died within hours after removal from the oxygen chambers. On the other hand, if LD50 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 LD50 sarin inhalation, and epinephrine may limit the ventilatory, inflammatory, and lethal effects of sarin. PMID:24269878

  7. Role of Dynamin Related Protein 1 (Drp1)-Mediated Mitochondrial Fission in Oxygen-Sensing and Constriction of the Ductus Arteriosus

    PubMed Central

    Hong, Zhigang; Kutty, Shelby; Toth, Peter T.; Marsboom, Glenn; Hammel, James M; Chamberlain, Carolyn; Ryan, John J.; Zhang, Hannah J.; Sharp, Willard W; Morrow, Erik; Trivedi, Kalyani; Weir, E. Kenneth; Archer, Stephen L.

    2014-01-01

    Rationale: Closure of the ductus arteriosus (DA) is essential for the transition from fetal to neonatal patterns of circulation. Initial PO2-dependent vasoconstriction causes functional DA closure within minutes. Within days a fibrogenic, proliferative mechanism causes anatomical closure. Though modulated by endothelial-derived vasodilators and constrictors, O2-sensing is intrinsic to ductal smooth muscle cells (DASMC) and oxygen-induced DA constriction persists in the absence of endothelium, endothelin and cyclooxygenase mediators. O2 increases mitochondrial-derived H2O2 (mitoROS), which constricts DASMC by raising intracellular calcium and activating rho kinase. However, the mechanism by which oxygen changes mitochondrial function is unknown. Objective: Determine whether mitochondrial fission is crucial for O2-induced DA constriction and closure. Methods and Results: Using DA harvested from 30 term infants during correction of congenital heart disease, as well as DA from term rabbits, we demonstrate that mitochondrial fission is crucial for O2-induced constriction and closure. O2 rapidly (<5 minutes) causes mitochondrial fission by a cyclin-dependent kinase-mediated phosphorylation of dynamin-related protein 1 (Drp1) at serine 616. Fission triggers a metabolic shift in the DASMC that activates pyruvate dehydrogenase and increases mitochondrial H2O2 production. Subsequently fission increases complex I activity. Mitochondrial-targeted catalase overexpression eliminates PO2-induced increases in mitoROS and cytosolic calcium. The small-molecule Drp1 inhibitor, Mdivi-1, and siDRP1 yield concordant results, inhibiting O2-induced constriction (without altering the response to phenylephrine or KCl) and preventing O2-induced increases in oxidative metabolism, cytosolic calcium and DASMC proliferation. Prolonged Drp1 inhibition reduces DA closure in a tissue culture model. Conclusions: Mitochondrial fission is an obligatory, early step in mammalian O2-sensing and offers a

  8. Left anterior descending coronary artery blood flow and left ventricular unloading during extracorporeal membrane oxygenation support in a swine model of acute cardiogenic shock.

    PubMed

    Brehm, Christoph; Schubert, Sarah; Carney, Elizabeth; Ghodsizad, Ali; Koerner, Michael; McCoach, Robert; El-Banayosy, Aly

    2015-02-01

    The impact of extracorporeal membrane oxygenation (ECMO) support on coronary blood flow and left ventricular unloading is still debated. This study aimed to further characterize the influence of ECMO on coronary artery blood flow and its ability to unload the left ventricle in a short-term model of acute cardiogenic shock. Seven anesthetized pigs were intubated and then underwent median sternotomy and cannulation for venoarterial (VA) ECMO. Flow in the left anterior descending (LAD) artery, left atrial pressure (LAP), left ventricular end-diastolic pressure (LVEDP), and mean arterial pressure (MAP) were measured before and after esmolol-induced cardiac dysfunction and after initiating VA-ECMO support. Induction of acute cardiogenic shock was associated with short-term increases in LAP from 8 ± 4 mm Hg to 18 ± 14 mm Hg (P = 0.9) and LVEDP from 5 ± 2 mm Hg to 13 ± 17 mm Hg (P = 0.9), and a decrease in MAP from 63 ± 16 mm Hg to 50 ± 24 mm Hg (P = 0.3). With VA-ECMO support, blood flow in the LAD increased from 28 ± 25 mL/min during acute unsupported cardiogenic shock to 67 ± 50 mL/min (P = 0.003), and LAP and LVEDP decreased to 8 + 5 mm Hg (P = 0.7) and 5 ± 3 mm Hg (P = 0.5), respectively. In this swine model of acute cardiogenic shock, VA-ECMO improved coronary blood flow and provided some degree of left ventricular unloading for the short duration of the study. PMID:24935151

  9. Remote sensing of atomic oxygen - Some observational difficulties in the use of the forbidden O I 1173-A and O I 1641-A transitions

    NASA Technical Reports Server (NTRS)

    Erdman, P. W.; Zipf, E. C.

    1987-01-01

    Recent sounding rocket and satellite studies suggest that simultaneous measurements of the O I 989-A and 1304-A resonance lines and of the forbidden 1172.6-A and 1641.3-A transitions would form the basis of a useful remote sensing technique for measuring the O I density and optical opacity of a planetary or stellar atmosphere. Because the 1172.6-A and 1641.3-A emissions are weak lines and are emitted in a wavelength region rich in spectral features, it is important to determine whether typical flight instruments can make measurements with sufficient spectral purity so that the remote sensing observations will yield accurate results. A detailed, high-resolution study of the far UV emission features in the regions surrounding the atomic oxygen transitions at 1172.6 and 1641.3 A was made. These spectra, which were excited by electron impact on O2 and N2, are presented in an attempt to display some potential sources of interference in aeronomical measurements of these O I lines. Both atomic and molecular emissions are found, and the spectral resolution necessary to make unambiguous measurements is discussed.

  10. Cellular oxygen sensing: Importins and exportins are mediators of intracellular localisation of prolyl-4-hydroxylases PHD1 and PHD2

    SciTech Connect

    Steinhoff, Amrei; Pientka, Friederike Katharina; Moeckel, Sylvia; Kettelhake, Antje; Hartmann, Enno; Koehler, Matthias; Depping, Reinhard

    2009-10-02

    Hypoxia-inducible factors are crucial in the regulatory process of oxygen homeostasis of vertebrate cells. Inhibition of prolyl hydroxylation of HIF-{alpha} subunits by prolyl-hydroxylases (PHD1, PHD2 and PHD3) leads to transcription of a greater number of hypoxia responsive genes. We have investigated the subcellular distribution and the molecular mechanisms regulating the intracellular allocation of PHD1 and PHD2. As reported earlier we find PHD1 located exclusively in the nucleus. We demonstrate that nuclear import of PHD1 occurs importin {alpha}/{beta} dependently and relies on a nuclear localisation signal (NLS). By contrast PHD2 is cycling between nucleus and cytoplasm, and nuclear import seems to be independent of 'classical' importin {alpha}/{beta} receptors. Furthermore, we reveal that the exit of PHD2 from the nucleus requires CRM1 and the N-terminal 100 amino acids of the protein. Our findings provide new insights into the mechanisms of the regulation of the oxygen sensor cascade of PHDs in different cellular compartments.