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Sample records for oxygen consumption rates

  1. Quantifying consumption rates of dissolved oxygen along bed forms

    NASA Astrophysics Data System (ADS)

    Boano, Fulvio; De Falco, Natalie; Arnon, Shai

    2016-04-01

    Streambed interfaces represent hotspots for nutrient transformations because they host different microbial species, and the evaluation of these reaction rates is important to assess the fate of nutrients in riverine environments. In this work we analyze a series of flume experiments on oxygen demand in dune-shaped hyporheic sediments under losing and gaining flow conditions. We employ a new modeling code to quantify oxygen consumption rates from observed vertical profiles of oxygen concentration. The code accounts for transport by molecular diffusion and water advection, and automatically determines the reaction rates that provide the best fit between observed and modeled concentration values. The results show that reaction rates are not uniformly distributed across the streambed, in agreement with the expected behavior predicted by hyporheic exchange theory. Oxygen consumption was found to be highly influenced by the presence of gaining or losing flow conditions, which controlled the delivery of labile DOC to streambed microorganisms.

  2. Oxygen Consumption Rates of Bacteria under Nutrient-Limited Conditions

    PubMed Central

    Riedel, Timothy E.; Nealson, Kenneth H.; Finkel, Steven E.

    2013-01-01

    Many environments on Earth experience nutrient limitation and as a result have nongrowing or very slowly growing bacterial populations. To better understand bacterial respiration under environmentally relevant conditions, the effect of nutrient limitation on respiration rates of heterotrophic bacteria was measured. The oxygen consumption and population density of batch cultures of Escherichia coli K-12, Shewanella oneidensis MR-1, and Marinobacter aquaeolei VT8 were tracked for up to 200 days. The oxygen consumption per CFU (QO2) declined by more than 2 orders of magnitude for all three strains as they transitioned from nutrient-abundant log-phase growth to the nutrient-limited early stationary phase. The large reduction in QO2 from growth to stationary phase suggests that nutrient availability is an important factor in considering environmental respiration rates. Following the death phase, during the long-term stationary phase (LTSP), QO2 values of the surviving population increased with time and more cells were respiring than formed colonies. Within the respiring population, a subpopulation of highly respiring cells increased in abundance with time. Apparently, as cells enter LTSP, there is a viable but not culturable population whose bulk community and per cell respiration rates are dynamic. This result has a bearing on how minimal energy requirements are met, especially in nutrient-limited environments. The minimal QO2 rates support the extension of Kleiber's law to the mass of a bacterium (100-fg range). PMID:23770901

  3. Metabolically Derived human ventilation rates: A revised approach based upon oxygen consumption rates (Final Report) 2009

    EPA Science Inventory

    The purpose of this report is to provide a revised approach for calculating an individual's ventilation rate directly from their oxygen consumption rate. This revised approach will be used to update the ventilation rate information in the Exposure Factors Handbook, which serve as...

  4. Plant respirometer enables high resolution of oxygen consumption rates

    NASA Technical Reports Server (NTRS)

    Foster, D. L.

    1966-01-01

    Plant respirometer permits high resolution of relatively small changes in the rate of oxygen consumed by plant organisms undergoing oxidative metabolism in a nonphotosynthetic state. The two stage supply and monitoring system operates by a differential pressure transducer and provides a calibrated output by digital or analog signals.

  5. Determining oxygen consumption rate and asphyxiation point in Chanodichthys mongolicus using an improved respirometer chamber

    NASA Astrophysics Data System (ADS)

    Geng, Longwu; Jiang, Haifeng; Tong, Guangxiang; Xu, Wei

    2016-05-01

    Knowledge of oxygen consumption rates and asphyxiation points in fish is important to determine appropriate stocking and water quality management in aquaculture. The oxygen consumption rate and asphyxiation point in Chanodichthys mongolicus were detected under laboratory conditions using an improved respirometer chamber. The results revealed that more accurate estimates can be obtained by adjusting the volume of the respirometer chamber, which may avoid system errors caused by either repeatedly adjusting fish density or selecting different equipment specifications. The oxygen consumption rate and asphyxiation point of C. mongolicus increased with increasing water temperature and decreasing fish size. Changes in the C. mongolicus oxygen consumption rate were divided into three stages at water temperatures of 11-33°C: (1) a low temperature oxygen consumption rate stage when water temperature was 11-19°C, (2) the optimum temperature oxygen consumption rate stage when water temperature was 19-23°C, and (3) a high temperature oxygen consumption rate stage when water temperature was > 27°C. The temperature quotients (Q10) obtained suggested that C. mongolicus preferred a temperature range of 19-23°C. At 19°C, C. mongolicus exhibited higher oxygen consumption rates during the day when the maximum values were observed at 10:00 and 14:00 than at night when the minimum occurred at 02:00.

  6. A new method for measuring the oxygen diffusion constant and oxygen consumption rate of arteriolar walls.

    PubMed

    Sasaki, Nobuhiko; Horinouchi, Hirohisa; Ushiyama, Akira; Minamitani, Haruyuki

    2012-01-01

    Oxygen transport is believed to primarily occur via capillaries and depends on the oxygen tension gradient between the vessels and tissues. As blood flows along branching arterioles, the O(2) saturation drops, indicating either consumption or diffusion. The blood flow rate, the O(2) concentration gradient, and Krogh's O(2) diffusion constant (K) of the vessel wall are parameters affecting O(2)delivery. We devised a method for evaluating K of arteriolar wall in vivo using phosphorescence quenching microscopy to measure the partial pressure of oxygen in two areas almost simultaneously. The K value of arteriolar wall (inner diameter, 63.5 ± 11.9 μm; wall thickness, 18.0 ± 1.2 μm) was found to be 6.0 ± 1.2 × 10(-11) (cm(2)/s)(ml O(2)·cm(-3) tissue·mmHg(-1)). The arteriolar wall O(2) consumption rate (M) was 1.5 ± 0.1 (ml O(2)·100 cm(-3) tissue·min(-1)), as calculated using Krogh's diffusion equation. These results suggest that the arteriolar wall consumes a considerable proportion of the O(2) that diffuses through it.

  7. A New Approach for Measuring Single-Cell Oxygen Consumption Rates

    PubMed Central

    Molter, Timothy W.; McQuaide, Sarah C.; Holl, Mark R.; Meldrum, Deirdre R.; Dragavon, Joseph M.; Anderson, Judith B.; Young, A. Cody; Burgess, Lloyd W.; Lidstrom, Mary E.

    2010-01-01

    A novel system that has enabled the measurement of single-cell oxygen consumption rates is presented. The experimental apparatus includes a temperature controlled environmental chamber, an array of microwells etched in glass, and a lid actuator used to seal cells in the microwells. Each microwell contains an oxygen sensitive platinum phosphor sensor used to monitor the cellular metabolic rates. Custom automation software controls the digital image data collection for oxygen sensor measurements, which are analyzed using an image-processing program to yield the oxygen concentration within each microwell versus time. Two proof-of-concept experiments produced oxygen consumption rate measurements for A549 human epithelial lung cancer cells of 5.39 and 5.27 fmol/min/cell, closely matching published oxygen consumption rates for bulk A549 populations. PMID:21057593

  8. The jumbo squid, Dosidicus gigas (Ommastrephidae), living in oxygen minimum zones I: Oxygen consumption rates and critical oxygen partial pressures

    NASA Astrophysics Data System (ADS)

    Trueblood, Lloyd A.; Seibel, Brad A.

    2013-10-01

    Dosidicus gigas is a large, metabolically active, epipelagic squid known to undertake diel vertical migrations across a large temperature and oxygen gradient in the Eastern Pacific. Hypoxia is known to cause metabolic suppression in D. gigas. However, the precise oxygen level at which metabolic suppression sets in is unknown. Here we describe a novel ship-board swim tunnel respirometer that was used to measure metabolic rates and critical oxygen partial pressures (Pcrit) for adult squids (2-7kg). Metabolic rate measurements were validated by comparison to the activity of the Krebs cycle enzyme, citrate synthase, in mantle muscle tissue (2-17kg). We recorded a mean routine metabolic rate of 5.91μmolg-1h-1 at 10°C and 12.62μmolg-1h-1 at 20°C. A temperature coefficient, Q10, of 2.1 was calculated. D. gigas had Pcrits of 1.6 and 3.8kPa at 10 and 20°C, respectively. Oxygen consumption rate (MO2) varied with body mass (M) according to MO2=11.57M-0.12±0.03 at 10°C. Citrate synthase activity varied with body mass according to Y=9.32M-0.19±0.02.

  9. Heart rate as an indicator of oxygen consumption: influence of body condition in the king penguin.

    PubMed

    Froget, G; Butler, P J; Handrich, Y; Woakes, A J

    2001-06-01

    The use of heart rate to estimate field metabolic rate has become a more widely used technique. However, this method also has some limitations, among which is the possible impact that several variables such as sex, body condition (i.e. body fat stores) and/or inactivity might have on the relationship between heart rate and rate of oxygen consumption. In the present study, we investigate the extent to which body condition can affect the use of heart rate as an indicator of the rate of oxygen consumption. Twenty-two breeding king penguins (Aptenodytes patagonicus) were exercised on a variable-speed treadmill. These birds were allocated to four groups according to their sex and whether or not they had been fasting. Linear regression equations were used to describe the relationship between heart rate and the rate of oxygen consumption for each group. There were significant differences between the regression equations for the four groups. Good relationships were obtained between resting and active oxygen pulses and an index of the body condition of the birds. Validation experiments on six courting king penguins showed that the use of a combination of resting oxygen pulse and active oxygen pulse gave the best estimate of the rate of oxygen consumption V(O2). The mean percentage error between predicted and measured V(O2) was only +0.81% for the six birds. We conclude that heart rate can be used to estimate rate of oxygen consumption in free-ranging king penguins even over a small time scale (30 min). However, (i) the type of activity of the bird must be known and (ii) the body condition of the bird must be accurately determined. More investigations on the impact of fasting and/or inactivity on this relationship are required to refine these estimates further. PMID:11441055

  10. Uptake Rate of Cationic Mitochondrial Inhibitor MKT-077 Determines Cellular Oxygen Consumption Change in Carcinoma Cells

    PubMed Central

    Chunta, John L.; Vistisen, Kerry S.; Yazdi, Zeinab; Braun, Rod D.

    2012-01-01

    Objective Since tumor radiation response is oxygen-dependent, radiosensitivity can be enhanced by increasing tumor oxygenation. Theoretically, inhibiting cellular oxygen consumption is the most efficient way to increase oxygen levels. The cationic, rhodacyanine dye-analog MKT-077 inhibits mitochondrial respiration and could be an effective metabolic inhibitor. However, the relationship between cellular MKT-077 uptake and metabolic inhibition is unknown. We hypothesized that rat and human mammary carcinoma cells would take up MKT-077, causing a decrease in oxygen metabolism related to drug uptake. Methods R3230Ac rat breast adenocarcinoma cells were exposed to MKT-077. Cellular MKT-077 concentration was quantified using spectroscopy, and oxygen consumption was measured using polarographic electrodes. MKT-077 uptake kinetics were modeled by accounting for uptake due to both the concentration and potential gradients across the plasma and mitochondrial membranes. These kinetic parameters were used to model the relationship between MKT-077 uptake and metabolic inhibition. MKT-077-induced changes in oxygen consumption were also characterized in MDA-MB231 human breast carcinoma cells. Results Cells took up MKT-077 with a time constant of ∼1 hr, and modeling showed that over 90% of intracellular MKT-077 was bound or sequestered, likely by the mitochondria. The uptake resulted in a rapid decrease in oxygen consumption, with a time constant of ∼30 minutes. Surprisingly the change in oxygen consumption was proportional to uptake rate, not cellular concentration. MKT-077 proved a potent metabolic inhibitor, with dose-dependent decreases of 45–73% (p = 0.003). Conclusions MKT-077 caused an uptake rate-dependent decrease in cellular metabolism, suggesting potential efficacy for increasing tumor oxygen levels and radiosensitivity in vivo. PMID:22616013

  11. Effect of nitroimidazoles on the oxygen consumption rate and respiratory control ratio of beef heart mitochondria

    SciTech Connect

    Chao, C.F.; Ting, L.; Subjeck, J.R.; Johnson, R.J.

    1984-08-01

    The neurotoxic effect of the nitroimidazole radiosensitizers misonidazole (MISO) and desmethylmisonidazole (DMM) has seriously compromised their clinical effectiveness. The authors compare here the effect of MISO and DMM on oxygen consumption in purified beef heart mitochondria. MISO has been found to significantly increase the oxygen consumption rate and decrease the respiratory control ratio in isolated mitochondria when incubated in the presence of the NAD+ dependent substrate, ..beta..-hydroxybutyrate. DMM has a similar but less pronounced effect than MISO on these respiratory parameters. When mitochondria were incubated in the presence of these radiosensitizers for 8, 15, 30, 45, and 60 minutes, the oxygen consumption rate was decreased when succinate, a FAD dependent substrate, was added following the incubation. This decrease, which is both time and dosage dependent, is equivalent for MISO and DMM.

  12. Effects of extracellular zinc ion on the rate of oxygen consumption of rat brain mitochondria.

    PubMed

    Kukoyi, B I

    2006-01-01

    The inhibitory effect of extracellular zinc ion on the rate of oxygen consumption of rat brain mitochondria pre-incubated in 1.0 mMol Ca(2+)EDTA were determined. There was a significant increase [P < 0.01] in the rate of oxygen consumption in the rat brain mitochondria pre-incubated in 1.0 mMol Ca(2+)EDTA in a succinate initiated reaction. The reverse was the case when the concentration of Ca(2+)EDTA was increased to 10 mMol. A 20 microMol zinc-aspartate was found to have no inhibitory effect on the rate of oxygen consumption of the brain mitochondria pre-incubated with 1.0 mMol Ca(2+)EDTA when compared with the control that lacked 1.0 mMol Ca(2+)EDTA, however there was a significant decrease [P < 0.01] in the rate of oxygen consumption of the rat brain mitochondria in the control experiment.

  13. Metabolically-Derived Human Ventilation Rates: A Revised Approach Based Upon Oxygen Consumption Rates (External Review Draft)

    EPA Science Inventory

    EPA has released a draft report entitled, Metabolically-Derived Human Ventilation Rates: A Revised Approach Based Upon Oxygen Consumption Rates, for independent external peer review and public comment. NCEA published the Exposure Factors Handbook in 1997. This comprehens...

  14. Estimating streambed travel times and respiration rates based on temperature and oxygen consumption

    NASA Astrophysics Data System (ADS)

    Vieweg, M.; Fleckenstein, J. H.; Schmidt, C.

    2015-12-01

    Oxygen consumption is a common proxy for aerobic respiration and novel in situ measurement techniques with high spatial resolution enable an accurate determination of the oxygen distribution in the streambed. The oxygen concentration at a certain location in the streambed depends on the input concentration, the respiration rate, temperature, and the travel time of the infiltrating flowpath. While oxygen concentrations and temperature can directly be measured, respiration rate and travel time must be estimated from the data. We investigated the interplay of these factors using a 6 month long, 5-min resolution dataset collected in a 3rdorder gravel-bed stream. Our objective was twofold, to determine transient rates of hyporheic respiration and to estimate travel times in the streambed based solely on oxygen and temperature measurements. Our results show that temperature and travel time explains ~70% of the variation in oxygen concentration in the streambed. Independent travel times were obtained using natural variations in the electrical conductivity (EC) of the stream water as tracer (µ=4.1 h; σ=2.3 h). By combining these travel times with the oxygen consumption, we calculated a first order respiration rate (µ=9.7 d-1; σ=6.1 d-1). Variations in the calculated respiration rate are largely explained by variations in streambed temperature. An empirical relationship between our respiration rate and temperature agrees with the theoretical Boltzmann-Arrhenius equation. With this relationship, a temperature-based respiration rate can be estimated and used to re-estimate subsurface travel times. The resulting travel times distinctively resemble the EC-derived travel times (R20.47; Nash-Sutcliffe coefficient 0.32). Both calculations of travel time are correlated to stream water levels and increase during discharge events, enhancing the oxygen consumption for these periods. No other physical factors besides temperature were significantly correlated with the respiration

  15. Diffusion and Monod kinetics to determine in vivo human corneal oxygen-consumption rate during soft contact-lens wear.

    PubMed

    Chhabra, Mahendra; Prausnitz, John M; Radke, C J

    2009-07-01

    The rate of oxygen consumption is an important parameter to assess the physiology of the human cornea. Metabolism of oxygen in the cornea is influenced by contact-lens-induced hypoxia, diseases such as diabetes, surgery, and drug treatment. Therefore, estimation of in vivo corneal oxygen-consumption rate is essential for gauging adequate oxygen supply to the cornea. Phosphorescence quenching of a dye coated on the posterior of a soft contact lens provides a powerful technique to measure tear-film oxygen tension (Harvitt and Bonanno, Invest Ophthalmol Vis Sci 1996;37:1026-1036; Bonanno et al., Invest Ophthalmol Vis Sci 2002;43:371-376). Unfortunately, previous work in establishing oxygen-consumption kinetics from transient postlens tear-film oxygen tensions relies on the simplistic assumption of a constant corneal-consumption rate. A more realistic model of corneal metabolism is needed to obtain reliable oxygen-consumption kinetics. Here, physiologically relevant nonlinear Monod kinetics is adopted for describing the local oxygen-consumption rate, thus avoiding aphysical negative oxygen tensions in the cornea. We incorporate Monod kinetics in an unsteady-state reactive-diffusion model for the cornea contact-lens system to determine tear-film oxygen tension as a function of time when changing from closed-eye to open-eye condition. The model was fit to available experimental data of in vivo human postlens tear-film oxygen tension to determine the corneal oxygen-consumption rate. Reliance on corneal oxygen diffusivity and solubility data obtained from rabbits is no longer requisite. Excellent agreement is obtained between the proposed model and experiment. We calculate the spatial-averaged in vivo human maximum corneal oxygen-consumption rate as Q(c)(max) = 1.05 x 10(-4) mL/(cm(3) s). The calculated Monod constant is K(m) = 2.2 mmHg.

  16. System for measuring oxygen consumption rates of mammalian cells in static culture under hypoxic conditions.

    PubMed

    Kagawa, Yuki; Miyahara, Hirotaka; Ota, Yuri; Tsuneda, Satoshi

    2016-01-01

    Estimating the oxygen consumption rates (OCRs) of mammalian cells in hypoxic environments is essential for designing and developing a three-dimensional (3-D) cell culture system. However, OCR measurements under hypoxic conditions are infrequently reported in the literature. Here, we developed a system for measuring OCRs at low oxygen levels. The system injects nitrogen gas into the environment and measures the oxygen concentration by an optical oxygen microsensor that consumes no oxygen. The developed system was applied to HepG2 cells in static culture. Specifically, we measured the spatial profiles of the local dissolved oxygen concentration in the medium, then estimated the OCRs of the cells. The OCRs, and also the pericellular oxygen concentrations, decreased nonlinearly as the oxygen partial pressure in the environment decreased from 19% to 1%. The OCRs also depended on the culture period and the matrix used for coating the dish surface. Using this system, we can precisely estimate the OCRs of various cell types under environments that mimic 3-D culture conditions, contributing crucial data for an efficient 3-D culture system design. PMID:26558344

  17. Detection of the oxygen consumption rate of migrating zebrafish by electrochemical equalization systems.

    PubMed

    Yasukawa, Tomoyuki; Koide, Masahiro; Tatarazako, Norihisa; Abe, Ryoko; Shiku, Hitoshi; Mizutani, Fumio; Matsue, Tomokazu

    2014-01-01

    A novel measurement system to determine oxygen consumption rates via respiration in migrating Zebrafish (Danio rerio) has been developed. A signal equalization system was adapted to detect oxygen in a chamber with one fish, because typical electrochemical techniques cannot measure respiration activities for migrating organisms. A closed chamber was fabricated using a pipet tip attached to a Pt electrode, and a columnar Vycor glass tip was used as the salt bridge. Pt electrode, which was attached to the chamber with one zebrafish, and Ag electrode were immersed in 10 mM potassium iodide (KI), and both the electrodes were connected externally to form a galvanic cell. Pt and Ag electrodes act as the cathode and anode to reduce oxygen and oxidize silver, respectively, allowing the deposition of insoluble silver iodide (AgI). The AgI acts as the signal source accumulated on the Ag electrode by conversion of oxygen. The amount of AgI deposited on the Ag electrode was determined by cathodic stripping voltammetry. The presence of zebrafish or its embryo led to a decrease in the stripping currents generated by a 10 min conversion of oxygen to AgI. The conversion of oxygen to AgI is disturbed by the migration of the zebrafish and allows the detection of different equalized signals corresponding to respiration activity. The oxygen consumption rates of the zebrafish and its embryo were estimated and determined to be ∼4.1 and 2.4 pmol·s(-1), respectively. The deposited AgI almost completely disappeared with a single stripping process. The signal equalization system provides a method to determine the respiration activities for migrating zebrafish and could be used to estimate environmental risk and for effective drug screening.

  18. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

    NASA Astrophysics Data System (ADS)

    Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

    2012-07-01

    This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

  19. Tide-related biological rhythm in the oxygen consumption rate of ghost shrimp (Neotrypaea uncinata).

    PubMed

    Leiva, Félix P; Niklitschek, Edwin J; Paschke, Kurt; Gebauer, Paulina; Urbina, Mauricio A

    2016-07-01

    The effects of tidal height (high and low), acclimation to laboratory conditions (days in captivity) and oxygen level (hypoxia and normoxia) were evaluated in the oxygen consumption rate (OCR) of the ghost shrimp Neotrypaea uncinata We evaluated the hypothesis that N. uncinata reduces its OCR during low tide and increases it during high tide, regardless of oxygen level or acclimation. Additionally, the existence of an endogenous rhythm in OCR was explored, and we examined whether it synchronized with tidal, diurnal or semidiurnal cycles. Unexpectedly, high OCRs were observed at low tide, during normoxia, in non-acclimated animals. Results from a second, longer experiment under normoxic conditions suggested the presence of a tide-related metabolic rhythm, a response pattern not yet demonstrated for a burrowing decapod. Although rhythms persisted for only 2 days after capture, their period of 12.8 h closely matched the semidiurnal tidal cycle that ghost shrimp confront inside their burrows. PMID:27099365

  20. Tide-related biological rhythm in the oxygen consumption rate of ghost shrimp (Neotrypaea uncinata).

    PubMed

    Leiva, Félix P; Niklitschek, Edwin J; Paschke, Kurt; Gebauer, Paulina; Urbina, Mauricio A

    2016-07-01

    The effects of tidal height (high and low), acclimation to laboratory conditions (days in captivity) and oxygen level (hypoxia and normoxia) were evaluated in the oxygen consumption rate (OCR) of the ghost shrimp Neotrypaea uncinata We evaluated the hypothesis that N. uncinata reduces its OCR during low tide and increases it during high tide, regardless of oxygen level or acclimation. Additionally, the existence of an endogenous rhythm in OCR was explored, and we examined whether it synchronized with tidal, diurnal or semidiurnal cycles. Unexpectedly, high OCRs were observed at low tide, during normoxia, in non-acclimated animals. Results from a second, longer experiment under normoxic conditions suggested the presence of a tide-related metabolic rhythm, a response pattern not yet demonstrated for a burrowing decapod. Although rhythms persisted for only 2 days after capture, their period of 12.8 h closely matched the semidiurnal tidal cycle that ghost shrimp confront inside their burrows.

  1. Oxygen consumption rate v. rate of energy utilization of fishes: a comparison and brief history of the two measurements.

    PubMed

    Nelson, J A

    2016-01-01

    Accounting for energy use by fishes has been taking place for over 200 years. The original, and continuing gold standard for measuring energy use in terrestrial animals, is to account for the waste heat produced by all reactions of metabolism, a process referred to as direct calorimetry. Direct calorimetry is not easy or convenient in terrestrial animals and is extremely difficult in aquatic animals. Thus, the original and most subsequent measurements of metabolic activity in fishes have been measured via indirect calorimetry. Indirect calorimetry takes advantage of the fact that oxygen is consumed and carbon dioxide is produced during the catabolic conversion of foodstuffs or energy reserves to useful ATP energy. As measuring [CO2 ] in water is more challenging than measuring [O2 ], most indirect calorimetric studies on fishes have used the rate of O2 consumption. To relate measurements of O2 consumption back to actual energy usage requires knowledge of the substrate being oxidized. Many contemporary studies of O2 consumption by fishes do not attempt to relate this measurement back to actual energy usage. Thus, the rate of oxygen consumption (M˙O2 ) has become a measurement in its own right that is not necessarily synonymous with metabolic rate. Because all extant fishes are obligate aerobes (many fishes engage in substantial net anaerobiosis, but all require oxygen to complete their life cycle), this discrepancy does not appear to be of great concern to the fish biology community, and reports of fish oxygen consumption, without being related to energy, have proliferated. Unfortunately, under some circumstances, these measures can be quite different from one another. A review of the methodological history of the two measurements and a look towards the future are included.

  2. Protein expression and oxygen consumption rate of early postmortem mitochondria relate to meat tenderness.

    PubMed

    Grabež, V; Kathri, M; Phung, V; Moe, K M; Slinde, E; Skaugen, M; Saarem, K; Egelandsdal, B

    2015-04-01

    Oxygen consumption rate (OCR) of muscle fibers from bovine semimembranosus muscle of 41 animals was investigated 3 to 4 h and 3 wk postmortem. Significant relations (P < 0.05) were found between OCR measurements and Warner-Bratzler shear force measurement. Muscles with high mitochondrial OCR after 3 to 4 h and low nonmitochondrial oxygen consumption gave more tender meat. Tender (22.92 ± 2.2 N/cm2) and tough (72.98 ± 7.2 N/cm2) meat samples (4 samples each), separated based on their OCR measurements, were selected for proteomic studies using mitochondria isolated approximately 2.5 h postmortem. Twenty-six differently expressed proteins (P < 0.05) were identified in tender meat and 19 in tough meat. In tender meat, the more prevalent antioxidant and chaperon enzymes may reduce reactive oxygen species and prolong oxygen removal by the electron transport system (ETS). Glycolytic, Krebs cycle, and ETS enzymes were also more abundant in tender meat

  3. A microwell array device capable of measuring single-cell oxygen consumption rates

    PubMed Central

    Molter, Timothy W.; McQuaide, Sarah C.; Suchorolski, Martin T.; Strovas, Tim J.; Burgess, Lloyd W.; Meldrum, Deirdre R.; Lidstrom, Mary E.

    2009-01-01

    Due to interest in cell population heterogeneity, the development of new technology and methodologies for studying single cells has dramatically increased in recent years. The ideal single cell measurement system would be high throughput for statistical relevance, would measure the most important cellular parameters, and minimize disruption of normal cell function. We have developed a microwell array device capable of measuring single cell oxygen consumption rates (OCR). This OCR device is able to diffusionally isolate single cells and enables the quantitative measurement of oxygen consumed by a single cell with fmol/min resolution in a non-invasive and relatively high throughput manner. A glass microwell array format containing fixed luminescent sensors allows for future incorporation of additional cellular parameter sensing capabilities. To demonstrate the utility of the OCR device, we determined the oxygen consumption rates of a small group of single cells (12 to 18) for three different cells lines: murine macrophage cell line RAW264.7, human epithelial lung cancer cell line A549, and human Barrett’s esophagus cell line CP-D. PMID:20084089

  4. Estimating oxygen consumption from heart rate using adaptive neuro-fuzzy inference system and analytical approaches.

    PubMed

    Kolus, Ahmet; Dubé, Philippe-Antoine; Imbeau, Daniel; Labib, Richard; Dubeau, Denise

    2014-11-01

    In new approaches based on adaptive neuro-fuzzy systems (ANFIS) and analytical method, heart rate (HR) measurements were used to estimate oxygen consumption (VO2). Thirty-five participants performed Meyer and Flenghi's step-test (eight of which performed regeneration release work), during which heart rate and oxygen consumption were measured. Two individualized models and a General ANFIS model that does not require individual calibration were developed. Results indicated the superior precision achieved with individualized ANFIS modelling (RMSE = 1.0 and 2.8 ml/kg min in laboratory and field, respectively). The analytical model outperformed the traditional linear calibration and Flex-HR methods with field data. The General ANFIS model's estimates of VO2 were not significantly different from actual field VO2 measurements (RMSE = 3.5 ml/kg min). With its ease of use and low implementation cost, the General ANFIS model shows potential to replace any of the traditional individualized methods for VO2 estimation from HR data collected in the field. PMID:24793823

  5. Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear

    PubMed Central

    Del Castillo, Luis F.; da Silva, Ana R. Ferreira; Hernández, Saul I.; Aguilella, M.; Andrio, Andreu; Mollá, Sergio; Compañ, Vicente

    2014-01-01

    Purpose We present an analysis of the corneal oxygen consumption Qc from non-linear models, using data of oxygen partial pressure or tension (pO2) obtained from in vivo estimation previously reported by other authors.1 Methods Assuming that the cornea is a single homogeneous layer, the oxygen permeability through the cornea will be the same regardless of the type of lens that is available on it. The obtention of the real value of the maximum oxygen consumption rate Qc,max is very important because this parameter is directly related with the gradient pressure profile into the cornea and moreover, the real corneal oxygen consumption is influenced by both anterior and posterior oxygen fluxes. Results Our calculations give different values for the maximum oxygen consumption rate Qc,max, when different oxygen pressure values (high and low pO2) are considered at the interface cornea-tears film. Conclusion Present results are relevant for the calculation on the partial pressure of oxygen, available at different depths into the corneal tissue behind contact lenses of different oxygen transmissibility. PMID:25649636

  6. The effect of submergence on heart rate and oxygen consumption of swimming seals and sea lions.

    PubMed

    Williams, T M; Kooyman, G L; Croll, D A

    1991-01-01

    Respiratory, metabolic, and cardiovascular responses to swimming were examined in two species of pinniped, the harbor seal (Phoca vitulina) and the California sea lion (Zalophus californianus). 1. Harbor seals remained submerged for 82-92% of the time at swimming speeds below 1.2 m.s-1. At higher speeds, including simulated speeds above 1.4 m.s-1, the percentage of time spent submerged decreased, and was inversely related to body weight. In contrast, the percentage of time spent submerged did not change with speed for sea lions swimming from 0.5 m.s-1 to 4.0 m.s-1. 2. During swimming, harbor seals showed a distinct breathhold bradycardia and ventilatory tachycardia that were independent of swimming speed. Average heart rate was 137 beats.min-1 when swimming on the water surface and 50 beats.min-1 when submerged. A bimodal pattern of heart rate also occurred in sea lions, but was not as pronounced as in the seals. 3. The weighted average heart rate (WAHR), calculated from measured heart rate and the percentage time spent on the water surface or submerged, increased linearly with swimming speed for both species. The graded increase in heart rate with exercise load is similar to the response observed for terrestrial mammals. 4. The rate of oxygen consumption increased exponentially with swimming speed in both seals and sea lions. The minimum cost of transport calculated from these rates ranged from 2.3 to 3.6 J.m-1.kg-1, and was 2.5-4.0 times the level predicted for similarly-sized salmonids. Despite different modes of propulsion and physiological responses to swimming, these pinnipeds demonstrate similar transport costs.

  7. Oxygen Consumption by Red Wines. Part I: Consumption Rates, Relationship with Chemical Composition, and Role of SO₂.

    PubMed

    Ferreira, Vicente; Carrascon, Vanesa; Bueno, Mónica; Ugliano, Maurizio; Fernandez-Zurbano, Purificación

    2015-12-30

    Fifteen Spanish red wines extensively characterized in terms of SO2, color, antioxidant indexes, metals, and polyphenols were subjected to five consecutive sensor-controlled cycles of air saturation at 25 °C. Within each cycle, O2 consumption rates cannot be interpreted by simple kinetic models. Plots of cumulated consumed O2 made it possible to define a fast and highly wine-dependent initial O2 consumption rate and a second and less variable average O2 consumption rate which remains constant in saturations 2 to 5. Both rates have been satisfactorily modeled, and in both cases they were independent of Fe and SO2 and highly dependent on Cu levels. Average rates were also related to Mn, pH, Folin, protein precipitable proanthocyanidins (PPAs), and polyphenolic profile. Initial rates were strong and negatively correlated to SO2 consumption, indicating that such an initial rate is either controlled by an unknown antioxidant present in some wines or affected by a poor real availability of SO2. Remaining unreacted SO2 is proportional to initial combined SO2 and to final free acetaldehyde.

  8. Oxygen Consumption by Red Wines. Part I: Consumption Rates, Relationship with Chemical Composition, and Role of SO₂.

    PubMed

    Ferreira, Vicente; Carrascon, Vanesa; Bueno, Mónica; Ugliano, Maurizio; Fernandez-Zurbano, Purificación

    2015-12-30

    Fifteen Spanish red wines extensively characterized in terms of SO2, color, antioxidant indexes, metals, and polyphenols were subjected to five consecutive sensor-controlled cycles of air saturation at 25 °C. Within each cycle, O2 consumption rates cannot be interpreted by simple kinetic models. Plots of cumulated consumed O2 made it possible to define a fast and highly wine-dependent initial O2 consumption rate and a second and less variable average O2 consumption rate which remains constant in saturations 2 to 5. Both rates have been satisfactorily modeled, and in both cases they were independent of Fe and SO2 and highly dependent on Cu levels. Average rates were also related to Mn, pH, Folin, protein precipitable proanthocyanidins (PPAs), and polyphenolic profile. Initial rates were strong and negatively correlated to SO2 consumption, indicating that such an initial rate is either controlled by an unknown antioxidant present in some wines or affected by a poor real availability of SO2. Remaining unreacted SO2 is proportional to initial combined SO2 and to final free acetaldehyde. PMID:26654524

  9. Oxygen consumption rate of early pre-antral follicles from vitrified human ovarian cortical tissue

    PubMed Central

    ISHIKAWA, Takayuki; KYOYA, Toshihiko; NAKAMURA, Yusuke; SATO, Eimei; TOMIYAMA, Tatsuhiro; KYONO, Koichi

    2014-01-01

    The study of human ovarian tissue transplantation and cryopreservation has advanced significantly. Autotransplantation of human pre-antral follicles isolated from cryopreserved cortical tissue is a promising option for the preservation of fertility in young cancer patients. The purpose of the present study was to reveal the effect of vitrification after low-temperature transportation of human pre-antral follicles by using the oxygen consumption rate (OCR). Cortical tissues from 9 ovaries of female-to-male transsexuals were vitrified after transportation (6 or 18 h). The follicles were enzymatically isolated from nonvitrified tissue (group I, 18 h of transportation), vitrified-warmed tissue (group II, 6 and 18 h of transportation) and vitrified-warmed tissue that had been incubated for 24 h (group III, 6 and 18 h of transportation). OCR measurement and the LIVE/DEAD viability assay were performed. Despite the ischemic condition, the isolated pre-antral follicles in group I consumed oxygen, and the mean OCRs increased with developmental stage. Neither the transportation time nor patient age seemed to affect the OCR in this group. Meanwhile, the mean OCR was significantly lower (P < 0.05) in group II but was comparable to that of group I after 24 h of incubation. The integrity of vitrified-warmed primordial and primary follicles was clearly corroborated by the LIVE/DEAD viability assay. These results demonstrate that the OCR can be used to directly estimate the effect of vitrification on the viability of primordial and primary follicles and to select the viable primordial and primary follicles from vitrified-warmed follicles. PMID:25262776

  10. Oxygen consumption and heart rate responses to isolated ballet exercise sets.

    PubMed

    Rodrigues-Krause, Josianne; Dos Santos Cunha, Giovani; Alberton, Cristine Lima; Follmer, Bruno; Krause, Mauricio; Reischak-Oliveira, Alvaro

    2014-01-01

    Ballet stage performances are associated with higher cardiorespiratory demand than rehearsals and classes. Hence, new interest is emerging to create periodized training that enhances dancers' fitness while minimizing delayed exercise-induced fatigue and possible injuries. Finding out in what zones of intensity dancers work during different ballet movements may support the use of supplemental training adjusted to the needs of the individual dancer. Therefore, the main purpose of this study was to describe dancers' oxygen consumption (VO2) and heart rate (HR) responses during the performance of nine isolated ballet exercise sets, as correlated with their first and second ventilatory thresholds (VT1 and VT2). Twelve female ballet dancers volunteered for the study. Their maximum oxygen consumption (VO2max), VT1, and VT2 were determined by use of an incremental treadmill test. Nine sets of ballet movements were assessed: pliés, tendus, jetés, rond de jambes, fondus, grand adage (adage), grand battements, temps levés, and sautés. The sets were randomly executed and separated by 5 minute rest periods. ANOVA for repeated measurements followed by the Bonferroni Post-hoc test were applied (p < 0.05). VO2 responses were as follows: pliés (17.6 ± 1.6 ml·kg(-1)·min(-1)); tendus and adage were not significantly greater than VT1; rond de jambes (21.8 ± 3.1 ml·kg(-1) ·min(-1)); fondus and jetés were higher than VT1 and the previous exercises; grand battements (25.8 ± 2.9 ml·kg(-1)·min(-1)) was greater than all the other exercises and VT1; and VT2 was significantly higher than all ballet sets. This stratification followed closely, but not exactly, the variation in HR. For example, rond de jambes (156.8 ± 19 b·min(-1)) did not show any significant difference from all the other ballet sets, nor VT1 or VT2. It is concluded that the workloads of isolated ballet sets, based on VO2 responses, vary between low and moderate aerobic intensity in relation to dancers' VT1 and

  11. Effects of temperature and dissolved oxygen content on oxygen consumption rate of Chinese prawn, giant tiger prawn and giant freshwater prawn

    NASA Astrophysics Data System (ADS)

    Dai, Xi-Lin; Zang, Wei-Ling; Wang, Wei-Dong; Shi, Yong-Hai; Liu, Wen-Cui; Xu, Gui-Rong; Li, Shi-Hua

    1999-06-01

    Temperature and the dissolved oxygen content affect the oxygen consumption of juveniles of Chinese prawn ( Penaeus chinensis), giant tiger prawn ( P. monodon) and giant freshwater prawn ( Macrobrachium rosenbergii). There is good correlation between the oxygen consumption rate ( V, mg/g·h) of the above three prawn species and the water temperature, and dissolved oxygen. In the range of test temperature, V increased with water temperature and dissolved oxygen content. The V of the above three prawn species increased 0.085 mg/g·h, 0.093 mg/g·h and 0.08 mg/g·h respectively with each °C of rising temperature. The comatose point and stifling point of the juveniles rose obviously at unsuitable temperature.

  12. Islet Oxygen Consumption Rate (OCR) Dose Predicts Insulin Independence in Clinical Islet Autotransplantation

    PubMed Central

    Papas, Klearchos K.; Bellin, Melena D.; Sutherland, David E. R.; Suszynski, Thomas M.; Kitzmann, Jennifer P.; Avgoustiniatos, Efstathios S.; Gruessner, Angelika C.; Mueller, Kathryn R.; Beilman, Gregory J.; Balamurugan, Appakalai N.; Loganathan, Gopalakrishnan; Colton, Clark K.; Koulmanda, Maria; Weir, Gordon C.; Wilhelm, Josh J.; Qian, Dajun; Niland, Joyce C.; Hering, Bernhard J.

    2015-01-01

    Background Reliable in vitro islet quality assessment assays that can be performed routinely, prospectively, and are able to predict clinical transplant outcomes are needed. In this paper we present data on the utility of an assay based on cellular oxygen consumption rate (OCR) in predicting clinical islet autotransplant (IAT) insulin independence (II). IAT is an attractive model for evaluating characterization assays regarding their utility in predicting II due to an absence of confounding factors such as immune rejection and immunosuppressant toxicity. Methods Membrane integrity staining (FDA/PI), OCR normalized to DNA (OCR/DNA), islet equivalent (IE) and OCR (viable IE) normalized to recipient body weight (IE dose and OCR dose), and OCR/DNA normalized to islet size index (ISI) were used to characterize autoislet preparations (n = 35). Correlation between pre-IAT islet product characteristics and II was determined using receiver operating characteristic analysis. Results Preparations that resulted in II had significantly higher OCR dose and IE dose (p<0.001). These islet characterization methods were highly correlated with II at 6–12 months post-IAT (area-under-the-curve (AUC) = 0.94 for IE dose and 0.96 for OCR dose). FDA/PI (AUC = 0.49) and OCR/DNA (AUC = 0.58) did not correlate with II. OCR/DNA/ISI may have some utility in predicting outcome (AUC = 0.72). Conclusions Commonly used assays to determine whether a clinical islet preparation is of high quality prior to transplantation are greatly lacking in sensitivity and specificity. While IE dose is highly predictive, it does not take into account islet cell quality. OCR dose, which takes into consideration both islet cell quality and quantity, may enable a more accurate and prospective evaluation of clinical islet preparations. PMID:26258815

  13. The relationship between energy-dependent phagocytosis and the rate of oxygen consumption in Tetrahymena.

    PubMed

    Skriver, L; Nilsson, J R

    1978-12-01

    The induction of high rates of food vacuole formation in Tetrahymena pyriformis increased the rate of respiration in exponentially growing cells by 17% and in starving cells by 47.5%. The increased rate of oxygen uptake was caused by phagocytosis itself, as shown by comparing the rates of respiration of a Tetrahymena mutant exposed to particles at the permissive or restrictive temperatures for food vacuole formation. During cell division, heat-synchronized cells in rich, particle-supplemented medium showed a significant decrease in the rate of respiration. Furthermore, dimethyl sulphoxide, in concentrations sufficient to block food vacuole formation, suppressed the rate of respiration to a level similar to that of starved cells. Cytochalasin B, fowever, did not reduce the rate of oxygen uptake despite the inability of the cells to complete the formation of food vacuoles during treatment; a possible explanation for this finding is discussed. There was a strong correlation between formation of food vacuoles and a high metabolic rate in Tetrahymena.

  14. Substantial energy expenditure for locomotion in ciliates verified by means of simultaneous measurement of oxygen consumption rate and swimming speed.

    PubMed

    Katsu-Kimura, Yumiko; Nakaya, Fumio; Baba, Shoji A; Mogami, Yoshihiro

    2009-06-01

    In order to characterize the energy expenditure of Paramecium, we simultaneously measured the oxygen consumption rate, using an optic fluorescence oxygen sensor, and the swimming speed, which was evaluated by the optical slice method. The standard metabolic rate (SMR, the rate of energy consumption exclusively for physiological activities other than locomotion) was estimated to be 1.18x10(-6) J h(-1) cell(-1) by extrapolating the oxygen consumption rate into one at zero swimming speed. It was about 30% of the total energy consumed by the cell swimming at a mean speed of 1 mm s(-1), indicating that a large amount of the metabolic energy (about 70% of the total) is consumed for propulsive activity only. The mechanical power liberated to the environment by swimming Paramecium was calculated on the basis of Stokes' law. This power, termed Stokes power, was 2.2x10(-9) J h(-1) cell(-1), indicating extremely low efficiency (0.078%) in the conversion of metabolic power to propulsion. Analysis of the cost of transport (COT, the energy expenditure for translocation per units of mass and distance) revealed that the efficiency of energy expenditure in swimming increases with speed rather than having an optimum value within a wide range of forced swimming, as is generally found in fish swimming. These characteristics of energy expenditure would be unique to microorganisms, including Paramecium, living in a viscous environment where large dissipation of the kinetic energy is inevitable due to the interaction with the surrounding water. PMID:19482999

  15. The relationship between body temperature, heart rate, breathing rate, and rate of oxygen consumption, in the tegu lizard (Tupinambis merianae) at various levels of activity.

    PubMed

    Piercy, Joanna; Rogers, Kip; Reichert, Michelle; Andrade, Denis V; Abe, Augusto S; Tattersall, Glenn J; Milsom, William K

    2015-12-01

    The present study determined whether EEG and/or EMG recordings could be used to reliably define activity states in the Brazilian black and white tegu lizard (Tupinambis merianae) and then examined the interactive effects of temperature and activity states on strategies for matching O2 supply and demand. In a first series of experiments, the rate of oxygen consumption (VO2), breathing frequency (fR), heart rate (fH), and EEG and EMG (neck muscle) activity were measured in different sleep/wake states (sleeping, awake but quiet, alert, or moving). In general, metabolic and cardio-respiratory changes were better indictors of the transition from sleep to wake than were changes in the EEG and EMG. In a second series of experiments, the interactive effects of temperature (17, 27 and 37 °C) and activity states on fR, tidal volume (VT), the fraction of oxygen extracted from the lung per breath (FIO2-FEO2), fH, and the cardiac O2 pulse were quantified to determine the relative roles of each of these variables in accommodating changes in VO2. The increases in oxygen supply to meet temperature- and activity-induced increases in oxygen demand were produced almost exclusively by increases in fH and fR. Regression analysis showed that the effects of temperature and activity state on the relationships between fH, fR and VO2 was to extend a common relationship along a single curve, rather than separate relationships for each metabolic state. For these lizards, the predictive powers of fR and fH were maximized when the effects of changes in temperature, digestive state and activity were pooled. However, the best r(2) values obtained were 0.63 and 0.74 using fR and fH as predictors of metabolic rate, respectively.

  16. The relationship between body temperature, heart rate, breathing rate, and rate of oxygen consumption, in the tegu lizard (Tupinambis merianae) at various levels of activity.

    PubMed

    Piercy, Joanna; Rogers, Kip; Reichert, Michelle; Andrade, Denis V; Abe, Augusto S; Tattersall, Glenn J; Milsom, William K

    2015-12-01

    The present study determined whether EEG and/or EMG recordings could be used to reliably define activity states in the Brazilian black and white tegu lizard (Tupinambis merianae) and then examined the interactive effects of temperature and activity states on strategies for matching O2 supply and demand. In a first series of experiments, the rate of oxygen consumption (VO2), breathing frequency (fR), heart rate (fH), and EEG and EMG (neck muscle) activity were measured in different sleep/wake states (sleeping, awake but quiet, alert, or moving). In general, metabolic and cardio-respiratory changes were better indictors of the transition from sleep to wake than were changes in the EEG and EMG. In a second series of experiments, the interactive effects of temperature (17, 27 and 37 °C) and activity states on fR, tidal volume (VT), the fraction of oxygen extracted from the lung per breath (FIO2-FEO2), fH, and the cardiac O2 pulse were quantified to determine the relative roles of each of these variables in accommodating changes in VO2. The increases in oxygen supply to meet temperature- and activity-induced increases in oxygen demand were produced almost exclusively by increases in fH and fR. Regression analysis showed that the effects of temperature and activity state on the relationships between fH, fR and VO2 was to extend a common relationship along a single curve, rather than separate relationships for each metabolic state. For these lizards, the predictive powers of fR and fH were maximized when the effects of changes in temperature, digestive state and activity were pooled. However, the best r(2) values obtained were 0.63 and 0.74 using fR and fH as predictors of metabolic rate, respectively. PMID:26285591

  17. Effects of sodium cyanide (nacn) on the endogenous rhythm of the oxygen consumption rate in the black rockfish sebastes schlegeli

    NASA Astrophysics Data System (ADS)

    Kim, Wan Soo; Kim, Jong Wook; Lee, Jae Hak; Huh, Sung Hoe

    2008-06-01

    Laboratory bioassays were conducted to test the acute toxicity effects of sudden exposure to sodium cyanide (NaCN) on the endogenous rhythm of the oxygen consumption rate (OCR) in the black rockfish Sebastes schlegeli. The OCR of the black rockfish (n = 14, total length = 20.4 ± 1.16 cm, wet weight = 158 ± 25 g) was measured with an automatic intermittentflow-respirometer. OCR decreased significantly when experimental fish were exposed to NaCN. When exposed to 10 ppb NaCN, fish were able to recover their OCR rhythmic activities. When fish were exposed to 20 ppb, however, the metabolic activity rhythms were not recovered. These results suggest that exposure to NaCN concentrations over 20 ppb cause severe physiological damage to the endogenous rhythms of black rockfish.

  18. In vitro measurements of oxygen consumption rates in hTERT-RPE cells exposed to low levels of red light

    NASA Astrophysics Data System (ADS)

    Wigle, Jeffrey C.; Castellanos, Cherry C.

    2016-03-01

    Exposure to 2.88 J/cm2 of red light induces an adaptive response against a lethal pulse of 2.0 μm laser radiation in hTERT-RPE cells in vitro, but not in a knockdown mutant for vascular endothelial growth factor c (VEGF-C). The generally accepted initiation sequence for photobiomodulation is that absorption of red light by cytochome c oxidase (CCOX) of the electron transport chain increases the binding affinity of CCOX for O2 vs. nitric oxide (NO). This results in displacement of NO by O2 in the active site of CCOX, thereby increasing cellular respiration and intracellular ATP. We've previously reported that red-light exposure induces a small, but consistently reproducible, increase in NO levels in these cells. But the relative importance of NO and oxidative phosphorylation is unclear because little is known about the relative contributions of NO and ATP to the response. However, if NO dissociation from CCOX actually increases oxidative phosphorylation, one should see a corresponding increase in oxygen consumption. A Seahorse Extracellular Flux Analyzer was used to measure oxygen consumption rates (OCR) in normal and mutant cells as a proxy for oxidative phosphorylation. Both basal respiration and maximum respiration rates in normal cells are significantly higher than in the mutant. The normal cells have a significant amount of "excess capacity," whereas the VEGF-C(KD) have little or none. The OCR in exposed normal cells is lower than in unexposed cells when measured immediately after exposure. The exposures used for these experiments had no effect on the OCR in mutant cells.

  19. Quantification of Low-Level Drug Effects Using Real-Time, in vitro Measurement of Oxygen Consumption Rate.

    PubMed

    Neal, Adam; Rountree, Austin M; Philips, Craig W; Kavanagh, Terrance J; Williams, Dominic P; Newham, Peter; Khalil, Gamal; Cook, Daniel L; Sweet, Ian R

    2015-12-01

    There is a general need to detect toxic effects of drugs during preclinical screening. We propose that increased sensitivity of xenobiotics toxicity combined with improved in vitro physiological recapitulation will more accurately assess potentially toxic perturbations of cellular biochemistry that are near in vivo pharmacological exposure levels. Importantly, measurement of such cytopathologies avoids activating mechanisms mediating toxicity at suprapharmacologic levels not relevant to in vivo effects. We present a sensitive method to measure changes in oxygen consumption rate (OCR), a well-established parameter reflecting a potential hazard, in response to exposure to pharmacologic levels of drugs using a flow culture system and state of the art oxygen sensing system. We tested metformin and acetaminophen on rat liver slices to illustrate the method. The features of the method include continuous and very stable measurement of OCR over the course of 48 h in liver slices in a continuous flow chamber with the ability to resolve changes as small as 0.3%/h. Kinetic modeling of metformin inhibition of OCR over a wide range of concentrations revealed both a slow and fast mechanism, where the fast mechanism activated only at concentrations above 0.6 mM. For both drugs, small amounts of inhibition were reversible, but higher decrements were irreversible. Overall the study highlights the advantages of measuring low-level toxicity so as to avoid the common extrapolations made about drug toxicity based on effects of drugs tested at suprapharmacologic levels.

  20. Quantification of Low-Level Drug Effects Using Real-Time, in vitro Measurement of Oxygen Consumption Rate.

    PubMed

    Neal, Adam; Rountree, Austin M; Philips, Craig W; Kavanagh, Terrance J; Williams, Dominic P; Newham, Peter; Khalil, Gamal; Cook, Daniel L; Sweet, Ian R

    2015-12-01

    There is a general need to detect toxic effects of drugs during preclinical screening. We propose that increased sensitivity of xenobiotics toxicity combined with improved in vitro physiological recapitulation will more accurately assess potentially toxic perturbations of cellular biochemistry that are near in vivo pharmacological exposure levels. Importantly, measurement of such cytopathologies avoids activating mechanisms mediating toxicity at suprapharmacologic levels not relevant to in vivo effects. We present a sensitive method to measure changes in oxygen consumption rate (OCR), a well-established parameter reflecting a potential hazard, in response to exposure to pharmacologic levels of drugs using a flow culture system and state of the art oxygen sensing system. We tested metformin and acetaminophen on rat liver slices to illustrate the method. The features of the method include continuous and very stable measurement of OCR over the course of 48 h in liver slices in a continuous flow chamber with the ability to resolve changes as small as 0.3%/h. Kinetic modeling of metformin inhibition of OCR over a wide range of concentrations revealed both a slow and fast mechanism, where the fast mechanism activated only at concentrations above 0.6 mM. For both drugs, small amounts of inhibition were reversible, but higher decrements were irreversible. Overall the study highlights the advantages of measuring low-level toxicity so as to avoid the common extrapolations made about drug toxicity based on effects of drugs tested at suprapharmacologic levels. PMID:26396153

  1. Light-addressable measurements of cellular oxygen consumption rates in microwell arrays based on phase-based phosphorescence lifetime detection

    PubMed Central

    Huang, Shih-Hao; Hsu, Yu-Hsuan; Wu, Chih-Wei; Wu, Chang-Jer

    2012-01-01

    A digital light modulation system that utilizes a modified commercial digital micromirror device (DMD) projector, which is equipped with a UV light-emitting diode as a light modulation source, has been developed to spatially direct excited light toward a microwell array device to detect the oxygen consumption rate (OCR) of single cells via phase-based phosphorescence lifetime detection. The microwell array device is composed of a combination of two components: an array of glass microwells containing Pt(II) octaethylporphine (PtOEP) as the oxygen-sensitive luminescent layer and a microfluidic module with pneumatically actuated glass lids set above the microwells to controllably seal the microwells of interest. By controlling the illumination pattern on the DMD, the modulated excitation light can be spatially projected to only excite the sealed microwell for cellular OCR measurements. The OCR of baby hamster kidney-21 fibroblast cells cultivated on the PtOEP layer within a sealed microwell has been successfully measured at 104 ± 2.96 amol s−1 cell−1. Repeatable and consistent measurements indicate that the oxygen measurements did not adversely affect the physiological state of the measured cells. The OCR of the cells exhibited a good linear relationship with the diameter of the microwells, ranging from 400 to 1000 μm and containing approximately 480 to 1200 cells within a microwell. In addition, the OCR variation of single cells in situ infected by Dengue virus with a different multiplicity of infection was also successfully measured in real-time. This proposed platform provides the potential for a wide range of biological applications in cell-based biosensing, toxicology, and drug discovery. PMID:24348889

  2. Effect of Arachidonic Acid on the Rate of Oxygen Consumption in Isolated Cardiomyocytes from Intact Rats and Animals with Ischemic or Diabetic Injury to the Heart.

    PubMed

    Egorova, M V; Kutsykova, T V; Afanas'ev, S A; Popov, S V

    2015-12-01

    We studied the rate of oxygen consumption by isolated cardiomyocytes from intact rats and animals with experimental myocardial infarction or streptozotocin-induced diabetes mellitus. The measurements were performed in standard incubation medium under various conditions of oxygenation and after addition of arachidonic acid (20 μmol/liter). Under normoxic conditions, arachidonic acid improves respiration of cardiomyocytes from intact animals, but reduces this parameter in cells isolated from animals with pathologies. The intensity of O2 consumption by cardiomyocytes from intact rats and animals with pathologies was shown to decrease during hypoxia. Addition of arachidonic acid aggravated inhibition of respiration for cardiomyocytes from intact rats and specimens with myocardial infarction, but had no effect in diabetes mellitus. The effect of arachidonic acid on oxygen consumption rate is probably mediated by a nonspecific mechanism realized at the mitochondrial level.

  3. Effects of auricular acupuncture on heart rate, oxygen consumption and blood lactic acid for elite basketball athletes.

    PubMed

    Lin, Zen-Pin; Chen, Yi-Hung; Fan, Chia; Wu, Huey-June; Lan, Lawrence W; Lin, Jaung-Geng

    2011-01-01

    This study investigated the effects of auricular acupuncture on athletes' recovery abilities after exercise. Subjects were selected from twenty-four male elite university basketball players, randomly divided into two groups: auricular acupuncture group (AAG), and normal control group (NCG), each group containing twelve subjects. Auricular acupuncture was experimented to each AAG athlete while no auricular acupuncture was conducted to each NCG athlete. Each subject in both groups performed a ride on the stationary bike until exhausted. The data of heart rate (HR(max)), oxygen consumption (VO(2 max)), and blood lactic acid were measured at four points of time: during the rest period after warm-ups and at the 5th, 30th and 60th minutes post-exercise, respectively. One-way ANOVA and repeated Scheffé methods were used to test the differences of the data between these two groups. The results showed that both HR(max) and blood lactic acid in AAG were significantly lower than those in NCG at the 30th and 60th minutes post-exercise. This suggests that auricular acupuncture can enhance athletes' recovery abilities after aggressive exercise.

  4. Scaling the amplitudes of the circadian pattern of resting oxygen consumption, body temperature and heart rate in mammals.

    PubMed

    Mortola, Jacopo P; Lanthier, Clement

    2004-09-01

    We questioned whether the amplitudes of the circadian pattern of body temperature (T(b)), oxygen consumption (V (O(2))) and heart rate (HR) changed systematically among species of different body weight (W). Because bodies of large mass have a greater heat capacitance than those of smaller mass, if the relative amplitude (i.e., amplitude/mean value) of metabolic rate was constant, one would expect the T(b) oscillation to decrease with the increase in the species W. We compiled data of T(b), V (O(2)) and HR from a literature survey of over 200 studies that investigated the circadian pattern of these parameters. Monotremata, Marsupials and Chiroptera, were excluded because of their characteristically low metabolic rate and T(b). The peak-trough ratios of V (O(2)) (42 species) and HR (35 species) averaged, respectively, 1.57+/-0.08, and 1.35+/-0.07, and were independent of W. The daily high values of T(b) did not change, while the daily low T(b) values slightly increased, with the species W; hence, the high-low T(b) difference (57 species) decreased with W (3.3 degrees C.W(-0.13)). However, the decrease in T(b) amplitude with W was much less than expected from physical principles, and the high-low T(b) ratio remained significantly above unity even in the largest mammals. Thus, it appears that in mammals, despite the huge differences in physical characteristics, the amplitude of the circadian pattern is a fixed (for V (O(2)) and HR), or almost fixed (for T(b)), fraction of the 24-h mean value. Presumably, the amplitudes of the oscillations are controlled parameters of physiological significance.

  5. Effects of aerobatics flight on oxygen consumption and heart rate control: influence on autonomic cardiovascular regulation during recovery.

    PubMed

    Guézennec, C Y; Louisy, F; Portier, H; Laude, D; Chapuis, B; Plésant, J

    2001-06-01

    Oxygen consumption (VO2) and blood pressure regulation were measured on five pilots during and after normal training aerobatics flights of a mean duration of 35 min. The acceleration vector along the longitudinal axis of the body (Gz) ranged from + 6.5 Gz to -3.5 Gz. VO2 was continuously monitored by a miniature telemetric system (K2). Heart rate (fc), the abdominal muscle electromyogram (EMG) and Gz levels were recorded synchronously on a magnetic tape recorder. A tilt test was performed pre- and post-flight to evaluate fc and blood-pressure variability. The left forearm blood flow was measured by strain-gauge plethysmography. The mean VO2 during flight was 1.2 l x min(-1), with a peak VO2 of 2.1 l x min x fc ranged between 55 and 165 beats x min(-1) and showed a progressive increase under the effect of + Gz, with a sudden fall during -Gz. The abdominal muscle EMG indicated the occurrence of muscle contraction under Gz load. Maximal responses were observed during the Gz phase. Comparison between pre- and post-flight data showed lower post-flight systolic blood pressure with higher fc. Before flight, upright tilt induced a significant increase in low/ high frequency fc, as assessed using spectral analysis. This change was suppressed after flight. In summary, these data show that aerobatics flight leads to enhanced energy expenditure, mainly because of increased skeletal muscle work. The post-flight tilt test showed that aerobatic flight favors parasympathetic drive and, consequently, modifies blood pressure regulation during recovery. This action may decrease + Gz tolerance to a second aerobatics flight performed shortly after the first.

  6. Simultaneous evaluation of substrate-dependent oxygen consumption rates and mitochondrial membrane potential by TMRM and safranin in cortical mitochondria.

    PubMed

    Chowdhury, Subir Roy; Djordjevic, Jelena; Albensi, Benedict C; Fernyhough, Paul

    2016-01-01

    Mitochondrial membrane potential (mtMP) is critical for maintaining the physiological function of the respiratory chain to generate ATP. The present study characterized the inter-relationship between mtMP, using safranin and tetramethyl rhodamine methyl ester (TMRM), and mitochondrial respiratory activity and established a protocol for functional analysis of mitochondrial bioenergetics in a multi-sensor system. Coupled respiration was decreased by 27 and 30-35% in the presence of TMRM and safranin respectively. Maximal respiration was higher than coupled with Complex I- and II-linked substrates in the presence of both dyes. Safranin showed decreased maximal respiration at a higher concentration of carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP) compared with TMRM. FCCP titration revealed that maximal respiration in the presence of glutamate and malate was not sustainable at higher FCCP concentrations as compared with pyruvate and malate. Oxygen consumption rate (OCR) and mtMP in response to mitochondrial substrates were higher in isolated mitochondria compared with tissue homogenates. Safranin exhibited higher sensitivity to changes in mtMP than TMRM. This multi-sensor system measured mitochondrial parameters in the brain of transgenic mice that model Alzheimer's disease (AD), because mitochondrial dysfunction is believed to be a primary event in the pathogenesis of AD. The coupled and maximal respiration of electron transport chain were decreased in the cortex of AD mice along with the mtMP compared with age-matched controls. Overall, these data demonstrate that safranin and TMRM are suitable for the simultaneous evaluation of mtMP and respiratory chain activity using isolated mitochondria and tissue homogenate. However, certain care should be taken concerning the selection of appropriate substrates and dyes for specific experimental circumstances. PMID:26647379

  7. Simultaneous evaluation of substrate-dependent oxygen consumption rates and mitochondrial membrane potential by TMRM and safranin in cortical mitochondria

    PubMed Central

    Chowdhury, Subir Roy; Djordjevic, Jelena; Albensi, Benedict C.; Fernyhough, Paul

    2015-01-01

    Mitochondrial membrane potential (mtMP) is critical for maintaining the physiological function of the respiratory chain to generate ATP. The present study characterized the inter-relationship between mtMP, using safranin and tetramethyl rhodamine methyl ester (TMRM), and mitochondrial respiratory activity and established a protocol for functional analysis of mitochondrial bioenergetics in a multi-sensor system. Coupled respiration was decreased by 27 and 30–35% in the presence of TMRM and safranin respectively. Maximal respiration was higher than coupled with Complex I- and II-linked substrates in the presence of both dyes. Safranin showed decreased maximal respiration at a higher concentration of carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP) compared with TMRM. FCCP titration revealed that maximal respiration in the presence of glutamate and malate was not sustainable at higher FCCP concentrations as compared with pyruvate and malate. Oxygen consumption rate (OCR) and mtMP in response to mitochondrial substrates were higher in isolated mitochondria compared with tissue homogenates. Safranin exhibited higher sensitivity to changes in mtMP than TMRM. This multi-sensor system measured mitochondrial parameters in the brain of transgenic mice that model Alzheimer's disease (AD), because mitochondrial dysfunction is believed to be a primary event in the pathogenesis of AD. The coupled and maximal respiration of electron transport chain were decreased in the cortex of AD mice along with the mtMP compared with age-matched controls. Overall, these data demonstrate that safranin and TMRM are suitable for the simultaneous evaluation of mtMP and respiratory chain activity using isolated mitochondria and tissue homogenate. However, certain care should be taken concerning the selection of appropriate substrates and dyes for specific experimental circumstances. PMID:26647379

  8. Simultaneous evaluation of substrate-dependent oxygen consumption rates and mitochondrial membrane potential by TMRM and safranin in cortical mitochondria.

    PubMed

    Chowdhury, Subir Roy; Djordjevic, Jelena; Albensi, Benedict C; Fernyhough, Paul

    2015-12-08

    Mitochondrial membrane potential (mtMP) is critical for maintaining the physiological function of the respiratory chain to generate ATP. The present study characterized the inter-relationship between mtMP, using safranin and tetramethyl rhodamine methyl ester (TMRM), and mitochondrial respiratory activity and established a protocol for functional analysis of mitochondrial bioenergetics in a multi-sensor system. Coupled respiration was decreased by 27 and 30-35% in the presence of TMRM and safranin respectively. Maximal respiration was higher than coupled with Complex I- and II-linked substrates in the presence of both dyes. Safranin showed decreased maximal respiration at a higher concentration of carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP) compared with TMRM. FCCP titration revealed that maximal respiration in the presence of glutamate and malate was not sustainable at higher FCCP concentrations as compared with pyruvate and malate. Oxygen consumption rate (OCR) and mtMP in response to mitochondrial substrates were higher in isolated mitochondria compared with tissue homogenates. Safranin exhibited higher sensitivity to changes in mtMP than TMRM. This multi-sensor system measured mitochondrial parameters in the brain of transgenic mice that model Alzheimer's disease (AD), because mitochondrial dysfunction is believed to be a primary event in the pathogenesis of AD. The coupled and maximal respiration of electron transport chain were decreased in the cortex of AD mice along with the mtMP compared with age-matched controls. Overall, these data demonstrate that safranin and TMRM are suitable for the simultaneous evaluation of mtMP and respiratory chain activity using isolated mitochondria and tissue homogenate. However, certain care should be taken concerning the selection of appropriate substrates and dyes for specific experimental circumstances.

  9. Deep-sea echinoderm oxygen consumption rates and an interclass comparison of metabolic rates in Asteroidea, Crinoidea, Echinoidea, Holothuroidea and Ophiuroidea.

    PubMed

    Hughes, Sarah Jane Murty; Ruhl, Henry A; Hawkins, Lawrence E; Hauton, Chris; Boorman, Ben; Billett, David S M

    2011-08-01

    Echinoderms are important components of deep-sea communities because of their abundance and the fact that their activities contribute to carbon cycling. Estimating the echinoderm contribution to food webs and carbon cycling is important to our understanding of the functioning of the deep-sea environment and how this may alter in the future as climatic changes take place. Metabolic rate data from deep-sea echinoderm species are, however, scarce. To obtain such data from abyssal echinoderms, a novel in situ respirometer system, the benthic incubation chamber system (BICS), was deployed by remotely operated vehicle (ROV) at depths ranging from 2200 to 3600 m. Oxygen consumption rates were obtained in situ from four species of abyssal echinoderm (Ophiuroidea and Holothuroidea). The design and operation of two versions of BICS are presented here, together with the in situ respirometry measurements. These results were then incorporated into a larger echinoderm metabolic rate data set, which included the metabolic rates of 84 echinoderm species from all five classes (Asteroidea, Crinoidea, Echinoidea, Holothuroidea and Ophiuroidea). The allometric scaling relationships between metabolic rate and body mass derived in this study for each echinoderm class were found to vary. Analysis of the data set indicated no change in echinoderm metabolic rate with depth (by class or phylum). The allometric scaling relationships presented here provide updated information for mass-dependent deep-sea echinoderm metabolic rate for use in ecosystem models, which will contribute to the study of both shallow water and deep-sea ecosystem functioning and biogeochemistry. PMID:21753044

  10. Spatial Variations in Vitreous Oxygen Consumption

    PubMed Central

    Murali, Karthik; Kang, Dongyang; Nazari, Hossein; Scianmarello, Nicholas; Cadenas, Enrique; Tai, Yu-Chong; Kashani, Amir; Humayun, Mark

    2016-01-01

    We investigated the spatial variation of vitreous oxygen consumption in enucleated porcine eyes. A custom made oxygen source was fabricated that could be localized to either the mid or posterior vitreous cavity and steady state vitreous oxygen tension was measured as a function of distance from the source using a commercially available probe. The reaction rate constant of ascorbate oxidation was estimated ex vivo by measuring the change in oxygen tension over time using vitreous harvested from porcine eyes. Vitreous ascorbate from mid and posterior vitreous was measured spectrophotometrically. When the oxygen source was placed in either the mid-vitreous (N = 6) or the posterior vitreous (N = 6), we measured a statistically significant decrease in vitreous oxygen tension as a function of distance from the oxygen source when compared to control experiments without an oxygen source; (p<0.005 for mid-vitreous and p<0.018 for posterior vitreous at all distances). The mid-vitreous oxygen tension change was significantly different from the posterior vitreous oxygen tension change at 2 and 3mm distances from the respective oxygen source (p<0.001). We also found a statistically significant lower concentration of ascorbate in the mid-vitreous as compared to posterior vitreous (p = 0.02). We determined the reaction rate constant, k = 1.61 M-1s-1 ± 0.708 M-1s-1 (SE), of the oxidation of ascorbate which was modeled following a second order rate equation. Our data demonstrates that vitreous oxygen consumption is higher in the posterior vitreous compared to the mid-vitreous. We also show spatial variations in vitreous ascorbate concentration. PMID:26930281

  11. Spatial Variations in Vitreous Oxygen Consumption.

    PubMed

    Murali, Karthik; Kang, Dongyang; Nazari, Hossein; Scianmarello, Nicholas; Cadenas, Enrique; Tai, Yu-Chong; Kashani, Amir; Humayun, Mark

    2016-01-01

    We investigated the spatial variation of vitreous oxygen consumption in enucleated porcine eyes. A custom made oxygen source was fabricated that could be localized to either the mid or posterior vitreous cavity and steady state vitreous oxygen tension was measured as a function of distance from the source using a commercially available probe. The reaction rate constant of ascorbate oxidation was estimated ex vivo by measuring the change in oxygen tension over time using vitreous harvested from porcine eyes. Vitreous ascorbate from mid and posterior vitreous was measured spectrophotometrically. When the oxygen source was placed in either the mid-vitreous (N = 6) or the posterior vitreous (N = 6), we measured a statistically significant decrease in vitreous oxygen tension as a function of distance from the oxygen source when compared to control experiments without an oxygen source; (p<0.005 for mid-vitreous and p<0.018 for posterior vitreous at all distances). The mid-vitreous oxygen tension change was significantly different from the posterior vitreous oxygen tension change at 2 and 3mm distances from the respective oxygen source (p<0.001). We also found a statistically significant lower concentration of ascorbate in the mid-vitreous as compared to posterior vitreous (p = 0.02). We determined the reaction rate constant, k = 1.61 M(-1) s(-1) ± 0.708 M(-1) s(-1) (SE), of the oxidation of ascorbate which was modeled following a second order rate equation. Our data demonstrates that vitreous oxygen consumption is higher in the posterior vitreous compared to the mid-vitreous. We also show spatial variations in vitreous ascorbate concentration.

  12. Oxygen consumption by a coral reef sponge.

    PubMed

    Hadas, Eran; Ilan, Micha; Shpigel, Muki

    2008-07-01

    Oxygen consumption of the Red Sea coral reef sponge Negombata magnifica was measured using both incubation and steady-state methods. The latter method was found to be the more reliable because sponge activity remained stable over time. Oxygen consumption rate was measured during three levels of sponge activity: full activity, reduced activity and basal activity (starved). It was found that the active oxygen consumption rate of N. magnifica averaged 37.3+/-4.6 nmol O2 min(-1) g(-1) wet mass, which is within the upper range reported for other tropical marine sponges. Fully active N. magnifica individuals consumed an average of 41.8+/-3.2 nmol O2 min(-1) g(-1) wet mass. The mean basal respiration rate was 20.2+/-1.2 nmol O2 min(-1) g(-1) wet mass, which is 51.6+/-2.5% of the active respiration rate. Therefore, the oxygen used for water pumping was calculated to be at most 10.6+/-1.8 nmol O2 min(-1) g(-1) wet mass, which is 25.1+/-3.6% of the total respiration. Combined oxygen used for maintenance and water pumping activity was calculated to be 30.8 nmol O2 min(-1) g(-1) wet mass, which is approximately 74% of the sponge's total oxygen requirement. The remaining oxygen is directed to other physiological activities, mainly the energy requirement of growth. These findings suggest that only a relatively minor amount of energy is potentially available for growth, and thus might be a factor in controlling the growth rate of N. magnifica in oligotrophic coral reefs.

  13. Estimation of the rate of oxygen consumption of the common eider duck (Somateria mollissima), with some measurements of heart rate during voluntary dives.

    PubMed

    Hawkins, P A; Butler, P J; Woakes, A J; Speakman, J R

    2000-09-01

    The relationship between heart rate (f(H)) and rate of oxygen consumption (V(O2)) was established for a marine diving bird, the common eider duck (Somateria mollissima), during steady-state swimming and running exercise. Both variables increased exponentially with speed during swimming and in a linear fashion during running. Eleven linear regressions of V(O2) (ml kg(-1 )min(-1)) on f(H) (beats min(-1)) were obtained: five by swimming and six by running the birds. The common regression was described by V(O2)=10.1 + 0.15f(H) (r(2)=0.46, N=272, P<0.0001). The accuracy of this relationship for predicting mean V(O2) was determined for a group of six birds by recording f(H) continuously over a 2-day period and comparing estimated V(O2) obtained using the common regression with (i) V(O2) estimated using the doubly labelled water technique (DLW) and (ii) V(O2) measured using respirometry. A two-pool model produced the most accurate estimated V(O2) using DLW. Because of individual variability within mean values of V(O2) estimated using both techniques, there was no significant difference between mean V(O2) estimated using f(H) or DLW and measured V(O2) values (P>0.2), although individual errors were substantially less when f(H) was used rather than DLW to estimate V(O2). Both techniques are, however, only suitable for estimating mean V(O2) for a group of animals, not for individuals. Heart rate and behaviour were monitored during a bout of 63 voluntary dives by one female bird in an indoor tank 1.7 m deep. Tachycardia occurred both in anticipation of and following each dive. Heart rate decreased before submersion but was above resting values for the whole of the dive cycle. Mean f(H) at mean dive duration was significantly greater than f(H) while swimming at maximum sustainable surface speeds. Heart rate was used to estimate mean V(O2) during the dive cycle and to predict aerobic dive limit (ADL) for shallow dives. PMID:10952881

  14. Maximal oxygen consumption increases with temperature in the European eel (Anguilla anguilla) through increased heart rate and arteriovenous extraction

    PubMed Central

    Claësson, Débora; Wang, Tobias; Malte, Hans

    2016-01-01

    Global warming results in increasing water temperature, which may represent a threat to aquatic ectotherms. The rising temperature affects ecology through physiology, by exerting a direct limiting effect on the individual. The mechanism controlling individual thermal tolerance is still elusive, but some evidence shows that the heart plays a central role, and that insufficient transport of oxygen to the respiring tissues may determine the thermal tolerance of animals. In this study, the influence of the heart in thermal limitation was investigated by measurements of aerobic scope in the European eel (Anguilla anguilla) together with measurements of cardiac output during rest and activity. Aerobic capacity was not limited by an acutely increased temperature in the European eel. Oxygen demand was met by an increase in heart rate and arteriovenous extraction. These findings suggest that thermal tolerance during exposure to acute temperature changes is not defined by oxygen transport capacity in the eel, and other mechanisms may play a central role in limiting thermal tolerance in these fish. PMID:27766150

  15. Feasibility of mapping the tissue mass corrected bioscale of cerebral metabolic rate of oxygen consumption using 17-oxygen and 23-sodium MR imaging in a human brain at 9.4 T.

    PubMed

    Atkinson, Ian C; Thulborn, Keith R

    2010-06-01

    The reduction of molecular oxygen to water is the final step of oxidative phosphorylation that couples adenosine triphosphate production to the reoxidation of reducing equivalents formed during the oxidation of glucose to carbon dioxide. This coupling makes the cerebral metabolic rate of oxygen consumption (CMRO(2)) an excellent reflection of the metabolic health of the brain. A multi-nuclear magnetic resonance (MR) imaging based method for CMRO(2) mapping is proposed. Oxygen consumption is determined by applying a new three-phase metabolic model for water generation and clearance to the changing 17-oxygen ((17)O) labeled water MR signal measured using quantitative (17)O MR imaging during inhalation of (17)O-enriched oxygen gas. These CMRO(2) data are corrected for the regional brain tissue mass computed from quantitative 23-sodium MR imaging of endogenous tissue sodium ions to derive quantitative results of oxygen consumption in micromoles O(2)/g tissue/minute that agree with literature results reported from positron emission tomography. The proposed technique is demonstrated in the human brain using a 9.4 T MR scanner optimized for human brain imaging.

  16. THE RESPIRATION OF LUMINOUS BACTERIA AND THE EFFECT OF OXYGEN TENSION UPON OXYGEN CONSUMPTION

    PubMed Central

    Shoup, Charles S.

    1929-01-01

    1. The respiration of luminous bacteria has been studied by colorimetric and manometric methods. 2. Limulus oxyhaemocyanin has been used as a colorimetric indicator of oxygen consumption and indicator dyes were used for colorimetric determination of carbon dioxide production. 3. The Thunberg-Winterstein microrespirometer has been used for the measurement of the rate of oxygen consumption by luminous bacteria at different partial pressures of oxygen. 4. The effect of oxygen concentration upon oxygen consumption has been followed from equilibrium with air to low pressures of oxygen. 5. Luminous bacteria consume oxygen and produce carbon dioxide independent of oxygen pressures from equilibrium with air (152 mm.) to approximately 22.80 mm. oxygen or 0.03 atmosphere. 6. Dimming of a suspension of luminous bacteria occurs when oxygen tension is lowered to approximately 2 mm. Hg (0.0026 atmosphere) and when the rate of respiration becomes diminished one-half. 7. Pure nitrogen stops respiratory activity and pure oxygen irreversibly inhibits oxygen consumption. 8. The curve for rate of oxygen consumption with oxygen concentration is similar to curves for adsorption of gasses at catalytic surfaces, and agrees with the Langmuir equation for the expression of the amount of gas adsorbed in unimolecular layer at catalytic surfaces with gas pressure. 9. A constant and maximum rate of oxygen consumption occurs in small cells when oxygen concentration becomes sufficient to entirely saturate the surface of the oxidative catalyst of the cell. PMID:19872507

  17. Evaluation of the effects of the metals Cd, Cr, Pb and their mixture on the filtration and oxygen consumption rates in catarina scallop, Argopecten ventricosus juveniles.

    PubMed

    Sobrino-Figueroa, Alma S; Cáceres-Martinez, Carlos

    2014-01-01

    In this work, we evaluated the effect of sublethal concentrations ( LC25, LC10 and LC5) of cadmium, chromium, lead, and their mixture on the filtration rate and oxygen consumption rate of Catarina scallop, Argopecten ventricosus (Sowerby, 1842), juveniles, in order to evaluate the use of these biomarkers as a reliable tool in environmental monitoring studies, because these metals have been found at high levels in water and sediments in the Mexican Pacific systems. An inverse dose-response relationship was observed when metal concentration and exposure time increased, the filtration rate and oxygen consumption rate reduced. The physiological responses evaluated in this study were sufficiently sensitive to detect alterations in the organisms at 0.014 mg l(-1) Cd, 0.311 mg l(-1) Cr, 0.125 mg l(-1) Pb and 0.05 mg l(-1) Cd + Cr + Pb at 24 and 72 hrs. Cd showed the most drastic effect. The Catarina scallop juveniles were more sensitive to Cd, Cr and Pb as compared to other bivalves. The biomarkers evaluated are a reliable tool to carry out environmental monitoring studies.

  18. Oxygen consumption in subseafloor basaltic crust

    NASA Astrophysics Data System (ADS)

    Orcutt, B. N.; Wheat, C. G.; Hulme, S.; Edwards, K. J.; Bach, W.

    2012-12-01

    Oceanic crust is the largest potential habitat for life on Earth and may contain a significant fraction of Earth's total microbial biomass, yet little is known about the form and function of life in this vast subseafloor realm that covers nearly two-thirds of the Earth's surface. A deep biosphere hosted in subseafloor basalts has been suggested from several lines of evidence; yet, empirical analysis of metabolic reaction rates in basaltic crust is lacking. Here we report the first measure of oxygen consumption in young (~ 8 Ma) and cool (<25 degrees C) basaltic crust, calculated from modeling oxygen and strontium profiles in basal sediments collected during Integrated Ocean Drilling Program (IODP) Expedition 336 to 'North Pond', a sediment 'pond' on the western flank of the Mid-Atlantic Ridge (MAR), where vigorous fluid circulation within basaltic crust occurs. Dissolved oxygen concentrations increased towards the sediment-basement interface, indicating an upward diffusional supply from oxic fluids circulating within the crust. A parametric reaction-transport model suggests oxygen consumption rates on the order of 0.5-500 nmol per cubic centimeter fluid per day in young and cool basaltic crust, providing sufficient energy to support a subsurface crustal biosphere.

  19. Comparison of oxygen consumption rates in minimally transformed BALB/3T3 and virus-transformed 3T3B-SV40 cells.

    PubMed

    Leznev, E I; Popova, I I; Lavrovskaja, V P; Evtodienko, Y V

    2013-08-01

    In the recent years, bioenergetics of tumor cells and particularly cell respiration have been attracting great attention because of the involvement of mitochondria in apoptosis and growing evidence of the possibility to diagnose and treat cancer by affecting the system of oxidative phosphorylation in mitochondria. In the present work, a comparative study of oxygen consumption in 3T3B-SV40 cells transformed with oncovirus SV40 and parental BALB/3T3 cells was conducted. Such fractions of oxygen consumption as "phosphorylating" respiration coupled to ATP synthesis, "free" respiration not coupled to ATP synthesis, and "reserve" or hidden respiration observed in the presence of protonophore were determined. Maximal respiration was shown to be only slightly decreased in 3T3B-SV40 cells as compared to BALB/3T3. However, in the case of certain fractions of cellular respiration, the changes were significant. "Phosphorylating" respiration was found to be reduced to 54% and "reserve" respiration, on the contrary, increased up to 160% in virus-transformed 3T3B-SV40 cells. The low rate of "phosphorylating" respiration and high "reserve" respiration indicate that under normal incubation conditions the larger part of mitochondrial respiratory chains of the virus-transformed cells is in the resting state (i.e. there is no electron transfer to oxygen). The high "reserve" respiration is suggested to play an important role in preventing apoptosis of 3T3B-SV40 cells.

  20. Oxygen consumption rates in hovering hummingbirds reflect substrate-dependent differences in P/O ratios: carbohydrate as a 'premium fuel'.

    PubMed

    Welch, Kenneth C; Altshuler, Douglas L; Suarez, Raul K

    2007-06-01

    The stoichiometric relationship of ATP production to oxygen consumption, i.e. the P/O ratio, varies depending on the nature of the metabolic substrate used. The latest estimates reveal a P/O ratio approximately 15% higher when glucose is oxidized compared with fatty acid oxidation. Because the energy required to produce aerodynamic lift for hovering is independent of the metabolic fuel oxidized, we hypothesized that the rate of oxygen consumption, VO2, should decline as the respiratory quotient, RQ (VCO2/VO2), increases from 0.71 to 1.0 as hummingbirds transition from a fasted to a fed state. Here, we show that hovering VO2 values in rufous (Selasphorus rufus) and Anna's hummingbirds (Calypte anna) are significantly greater when fats are metabolized (RQ=0.71) than when carbohydrates are used (RQ=1.0). Because hummingbirds gained mass during our experiments, making mass a confounding variable, we estimated VO2 per unit mechanical power output. Expressed in this way, the difference in VO2 when hummingbirds display an RQ=0.71 (fasted) and an RQ=1.0 (fed) is between 16 and 18%, depending on whether zero or perfect elastic energy storage is assumed. These values closely match theoretical expectations, indicating that a combination of mechanical power estimates and ;indirect calorimetry', i.e. the measurement of rates of gas exchange, enables precise estimates of ATP turnover and metabolic flux rates in vivo. The requirement for less oxygen when oxidizing carbohydrate suggests that carbohydrate oxidation may facilitate hovering flight in hummingbirds at high altitude.

  1. Modeling the Oxygen Consumption Rates in Pacific Salmon and Steelhead: An Assessment of Current Models and Practices

    SciTech Connect

    Trudel, Marc; Geist, David R.; Welch, David W.

    2004-03-01

    Bioenergetic models of fish have been used to study a large number of processes. Like most models, bioenergetic models require the estimation of numerous parameters. As a consequence, they have often relied on parameters borrowed from other species or values extrapolated from other life stages or size-classes. The magnitude of the biases associated with these practices remains largely unknown. The objective of this study was to determine whether or not metabolic rates could be extrapolated between closely related species and life stages. We focused on Pacific salmon Oncorhynchus spp. and steelhead O. mykiss, as the metabolic rates of these species have been well documented. Our analyses showed that models derived from closely related species did not accurately predict the metabolic rates of salmon, indicating that the practice of "species borrowing" should be avoided in assessing fish metabolic rates. Our work also showed that allometric equations of metabolic rates were not stable when measured over small size ranges and that biases could be introduced when these models are extrapolated to smaller or larger fish. In addition, we found that, except for steelhead, published models of Pacific salmon metabolic rate were inaccurate. Mean bias ranged from close to 0% to over 200% depending on size and water temperature, with about two-thirds of the bias values exceeding 20%. These biases could have large impacts on bioenergetic model predictions. Increased funding and scientific recognition of the need for additional basic research will be necessary to build more accurate bioenergetic models for Pacific salmon, especially models applied to the ocean phase of the life cycle.

  2. Development of a new oxygen consumption rate assay in cultures of Acanthamoeba (Protozoa: Lobosea) and its application to evaluate viability and amoebicidal activity in vitro.

    PubMed

    Heredero-Bermejo, I; Criado-Fornelio, A; Soliveri, J; Díaz-Martín, J A; Matilla-Fuentes, J; Sánchez-Arias, J A; Copa-Patiño, J L; Pérez-Serrano, J

    2015-08-01

    A new fluorometric method has been developed for measuring the oxygen consumption rate (OCR) of Acanthamoeba cultures in microplates and for screening molecules with amoebicidal activity against this microorganism. The use of a biofunctional matrix (containing an oxygen-sensitive fluorogenic probe) attached to the microplate wells allowed continuous measurement of OCR in the medium, hence assessment of amoebic growth. The new OCR method applied to cell viability yielded a linear relationship and monitoring was much quicker than with indirect viability assays previously used. In addition, two drugs were tested in a cytotoxicity assay monitored by the new OCR viability test. With this procedure, the standard amoebicidal drug chlorhexidine digluconate showed an IC50 of 3.53 + 1.3 mg/l against Acanthamoeba polyphaga and 3.19 + 1.2 mg/l against Acanthamoeba castellanii, whereas a cationic dendrimer [G1Si(NMe3+)4] showed an IC50 of 6.42 + 1.3 mg/l against A. polyphaga. These data agree with previous studies conducted in our laboratory. Therefore, the new OCR method has proven powerful and quick for amoebicidal drug screening and is likely to be applied in biochemical studies concerning protozoa respiration and metabolism.

  3. Retinoic acid-induced differentiation increases the rate of oxygen consumption and enhances the spare respiratory capacity of mitochondria in SH-SY5Y cells.

    PubMed

    Xun, Zhiyin; Lee, Do-Yup; Lim, James; Canaria, Christie A; Barnebey, Adam; Yanonne, Steven M; McMurray, Cynthia T

    2012-04-01

    Retinoic acid (RA) is used in differentiation therapy to treat a variety of cancers including neuroblastoma. The contributing factors for its therapeutic efficacy are poorly understood. However, mitochondria (MT) have been implicated as key effectors in RA-mediated differentiation process. Here we utilize the SH-SY5Y human neuroblastoma cell line as a model to examine how RA influences MT during the differentiation process. We find that RA confers an approximately sixfold increase in the oxygen consumption rate while the rate of glycolysis modestly increases. RA treatment does not increase the number of MT or cause measurable changes in the composition of the electron transport chain. Rather, RA treatment significantly increases the mitochondrial spare respiratory capacity. We propose a competition model for the therapeutic effects of RA. Specifically, the high metabolic rate in differentiated cells limits the availability of metabolic nutrients for use by the undifferentiated cells and suppresses their growth. Thus, RA treatment provides a selective advantage for the differentiated state.

  4. Rat splanchnic net oxygen consumption, energy implications.

    PubMed Central

    Casado, J; Fernández-López, J A; Esteve, M; Rafecas, I; Argilés, J M; Alemany, M

    1990-01-01

    1. The blood flow, PO2, pH and PCO2 have been estimated in portal and suprahepatic veins as well as in hepatic artery of fed and overnight starved rats given an oral glucose load. From these data the net intestinal, hepatic and splanchnic balances for oxygen and bicarbonate were calculated. The oxygen consumption of the intact animal has also been measured under comparable conditions. 2. The direct utilization of oxygen balances as energy equivalents when establishing the contribution of energy metabolism of liver and intestine to the overall energy expenses of the rat, has been found to be incorrect, since it incorporates the intrinsic error of interorgan proton transfer through bicarbonate. Liver and intestine produced high net bicarbonate balances in all situations tested, implying the elimination (by means of oxidative pathways, i.e. consuming additional oxygen) of high amounts of H+ generated with bicarbonate. The equivalence in energy output of the oxygen balances was then corrected for bicarbonate production to 11-54% lower values. 3. Intestine and liver consume a high proportion of available oxygen, about one-half in basal (fed or starved) conditions and about one-third after gavage, the intestine consumption being about 15% in all situations tested and the liver decreasing its oxygen consumption with gavage. PMID:2129230

  5. Induction of microcin B17 formation in Escherichia coli ZK650 by limitation of oxygen and glucose is independent of glucose consumption rate

    NASA Technical Reports Server (NTRS)

    Gao, Q.; Fang, A.; Demain, A. L.

    2001-01-01

    We examined the consumption of glucose from the media in which Escherichia coli ZK650 was grown. This organism, which produces the polypeptide antibiotic microcin B17 best under conditions of limiting supplies of glucose and air, was grown with a low level of glucose (0.5 mg/ml) as well as a high level (5.0 mg/ml) under both high and low aeration. Glucose consumption rates were virtually identical under both high and low aeration. Thus, glucose consumption rate is not a regulating factor in microcin B17 formation.

  6. Induction of microcin B17 formation in Escherichia coli ZK650 by limitation of oxygen and glucose is independent of glucose consumption rate.

    PubMed

    Gao, Q; Fang, A; Demain, A L

    2001-06-01

    We examined the consumption of glucose from the media in which Escherichia coli ZK650 was grown. This organism, which produces the polypeptide antibiotic microcin B17 best under conditions of limiting supplies of glucose and air, was grown with a low level of glucose (0.5 mg/ml) as well as a high level (5.0 mg/ml) under both high and low aeration. Glucose consumption rates were virtually identical under both high and low aeration. Thus, glucose consumption rate is not a regulating factor in microcin B17 formation.

  7. Oxygen consumption by bovine granulosa cells with prediction of oxygen transport in preantral follicles.

    PubMed

    Li, Dongxing; Redding, Gabe P; Bronlund, John E

    2013-01-01

    The rate of oxygen consumption by granulosa cells is a key parameter in mathematical models that describe oxygen transport across ovarian follicles. This work measured the oxygen consumption rate of bovine granulosa cells in vitro to be in the range 2.1-3.3×10⁻¹⁶ mol cell⁻¹ s⁻¹ (0.16-0.25 mol m⁻³ s⁻¹). The implications of the rates for oxygen transport in large bovine preantral follicles were examined using a mathematical model. The results indicate that oocyte oxygenation becomes increasingly constrained as preantral follicles grow, reaching hypoxic levels near the point of antrum formation. Beyond a preantral follicle radius of 134 µm, oxygen cannot reach the oocyte surface at typical values of model parameters. Since reported sizes of large bovine preantral follicles range from 58 to 145 µm in radius, this suggests that oocyte oxygenation is possible in all but the largest preantral follicles, which are on the verge of antrum formation. In preantral bovine follicles, the oxygen consumption rate of granulosa cells and fluid voidage will be the key determinants of oxygen levels across the follicle.

  8. On the depth and scale of metabolic rate variation: scaling of oxygen consumption rates and enzymatic activity in the Class Cephalopoda (Mollusca).

    PubMed

    Seibel, Brad A

    2007-01-01

    Recent ecological theory depends, for predictive power, on the apparent similarity of metabolic rates within broad taxonomic or functional groups of organisms (e.g. invertebrates or ectotherms). Such metabolic commonality is challenged here, as I demonstrate more than 200-fold variation in metabolic rates independent of body mass and temperature in a single class of animals, the Cephalopoda, over seven orders of magnitude size range. I further demonstrate wide variation in the slopes of metabolic scaling curves. The observed variation in metabolism reflects differential selection among species for locomotory capacity rather than mass or temperature constraints. Such selection is highest among epipelagic squids (Lolignidae and Ommastrephidae) that, as adults, have temperature-corrected metabolic rates higher than mammals of similar size.

  9. Oxygen consumption of human heart cells in monolayer culture.

    PubMed

    Sekine, Kaori; Kagawa, Yuki; Maeyama, Erina; Ota, Hiroki; Haraguchi, Yuji; Matsuura, Katsuhisa; Shimizu, Tatsuya

    2014-09-26

    Tissue engineering in cardiovascular regenerative therapy requires the development of an efficient oxygen supply system for cell cultures. However, there are few studies which have examined human cardiomyocytes in terms of oxygen consumption and metabolism in culture. We developed an oxygen measurement system equipped with an oxygen microelectrode sensor and estimated the oxygen consumption rates (OCRs) by using the oxygen concentration profiles in culture medium. The heart is largely made up of cardiomyocytes, cardiac fibroblasts, and cardiac endothelial cells. Therefore, we measured the oxygen consumption of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs), cardiac fibroblasts, human cardiac microvascular endothelial cell and aortic smooth muscle cells. Then we made correlations with their metabolisms. In hiPSC-CMs, the value of the OCR was 0.71±0.38pmol/h/cell, whereas the glucose consumption rate and lactate production rate were 0.77±0.32pmol/h/cell and 1.61±0.70pmol/h/cell, respectively. These values differed significantly from those of the other cells in human heart. The metabolism of the cells that constitute human heart showed the molar ratio of lactate production to glucose consumption (L/G ratio) that ranged between 1.97 and 2.2. Although the energy metabolism in adult heart in vivo is reported to be aerobic, our data demonstrated a dominance of anaerobic glycolysis in an in vitro environment. With our measuring system, we clearly showed the differences in the metabolism of cells between in vivo and in vitro monolayer culture. Our results regarding cell OCRs and metabolism may be useful for future tissue engineering of human heart.

  10. Critical windows in embryonic development: Shifting incubation temperatures alter heart rate and oxygen consumption of Lake Whitefish (Coregonus clupeaformis) embryos and hatchlings.

    PubMed

    Eme, J; Mueller, C A; Manzon, R G; Somers, C M; Boreham, D R; Wilson, J Y

    2015-01-01

    Critical windows are periods of developmental susceptibility when the phenotype of an embryonic, juvenile or adult animal may be vulnerable to environmental fluctuations. Temperature has pervasive effects on poikilotherm physiology, and embryos are especially vulnerable to temperature shifts. To identify critical windows, we incubated whitefish embryos at control temperatures of 2°C, 5°C, or 8°C, and shifted treatments among temperatures at the end of gastrulation or organogenesis. Heart rate (fH) and oxygen consumption ( [Formula: see text] ) were measured across embryonic development, and [Formula: see text] was measured in 1-day old hatchlings. Thermal shifts, up or down, from initial incubation temperatures caused persistent changes in fH and [Formula: see text] compared to control embryos measured at the same temperature (2°C, 5°C, or 8°C). Most prominently, when embryos were measured at organogenesis, shifting incubation temperature after gastrulation significantly lowered [Formula: see text] or fH. Incubation at 2°C or 5°C through gastrulation significantly lowered [Formula: see text] (42% decrease) and fH (20% decrease) at 8°C, incubation at 2°C significantly lowered [Formula: see text] (40% decrease) and fH (30% decrease) at 5°C, and incubation at 5°C and 8°C significantly lowered [Formula: see text] at 2°C (27% decrease). Through the latter half of development, [Formula: see text] and fH in embryos were not different from control values for thermally shifted treatments. However, in hatchlings measured at 2°C, [Formula: see text] was higher in groups incubated at 5°C or 8°C through organogenesis, compared to 2°C controls (43 or 65% increase, respectively). Collectively, these data suggest that embryonic development through organogenesis represents a critical window of embryonic and hatchling phenotypic plasticity. This study presents an experimental design that identified thermally sensitive periods for fish embryos.

  11. Oxygen consumption in weakly electric Neotropical fishes.

    PubMed

    Julian, David; Crampton, William G R; Wohlgemuth, Stephanie E; Albert, James S

    2003-12-01

    Weakly electric gymnotiform fishes with wave-type electric organ discharge (EOD) are less hypoxia-tolerant and are less likely to be found in hypoxic habitats than weakly electric gymnotiforms with pulse-type EOD, suggesting that differences in metabolism resulting from EOD type affects habitat choice. Although gymnotiform fishes are common in most Neotropical freshwaters and represent the dominant vertebrates in some habitats, the metabolic rates of these unique fishes have never been determined. In this study, O(2) consumption rates during EOD generation are reported for 34 gymnotiforms representing 23 species, all five families and 17 (59%) of the 28 genera. Over the size range sampled (0.4 g to 125 g), O(2) consumption of gymnotiform fishes was dependent on body mass, as expected, fitting a power function with a scaling exponent of 0.74, but the O(2) consumption rate was generally about 50% of that expected by extrapolation of temperate teleost metabolic rates to a similar ambient temperature (26 degrees C). O(2) consumption rate was not dependent on EOD type, but maintenance of "scan swimming" (continuous forwards and backwards swimming), which is characteristic only of gymnotiforms with wave-type EODs, increased O(2) consumption 2.83+/-0.49-fold (mean+/-SD). This suggests that the increased metabolic cost of scan swimming could restrict gymnotiforms with wave-type EODs from hypoxic habitats.

  12. The Rate of Oxygen Utilization by Cells

    PubMed Central

    Wagner, Brett A.; Venkataraman, Sujatha; Buettner, Garry R.

    2011-01-01

    The discovery of oxygen is considered by some to be the most important scientific discovery of all time – from both physical-chemical/astrophysics and biology/evolution viewpoints. One of the major developments during evolution is the ability to capture dioxygen in the environment and deliver it to each cell in the multicellular, complex mammalian body -- on demand, i.e. just-in-time. Humans use oxygen to extract approximately 2550 Calories (10.4 MJ) from food to meet daily energy requirements. This combustion requires about 22 moles of dioxygen per day, or 2.5 × 10-4 mol s-1. This is an average rate of oxygen utilization of 2.5 × 10-18 mol cell-1 s-1, i.e. 2.5 amol cell-1 s-1. Cells have a wide range of oxygen utilization, depending on cell type, function, and biological status. Measured rates of oxygen utilization by mammalian cells in culture range from <1 to >350 amol cell-1 s-1. There is a loose positive linear correlation of the rate of oxygen consumption (OCR) by mammalian cells in culture with cell volume and cell protein. The use of oxygen by cells and tissues is an essential aspect of the basic redox biology of cells and tissues. This type of quantitative information is fundamental to investigations in quantitative redox biology, especially redox systems biology. PMID:21664270

  13. Comparative quantification of oxygen release by wetland plants: electrode technique and oxygen consumption model.

    PubMed

    Wu, Haiming; Liu, Jufeng; Zhang, Jian; Li, Cong; Fan, Jinlin; Xu, Xiaoli

    2014-01-01

    Understanding oxygen release by plants is important to the design of constructed wetlands for wastewater treatment. Lab-scale systems planted with Phragmites australis were studied to evaluate the amount of oxygen release by plants using electrode techniques and oxygen consumption model. Oxygen release rate (0.14 g O2/m(2)/day) measured using electrode techniques was much lower than that (3.94-25.20 gO2/m(2)/day) calculated using the oxygen consumption model. The results revealed that oxygen release by plants was significantly influenced by the oxygen demand for the degradation of pollutants, and the oxygen release rate increased with the rising of the concentration of degradable materials in the solution. The summary of the methods in qualifying oxygen release by wetland plants demonstrated that variations existed among different measuring methods and even in the same measuring approach. The results would be helpful for understanding the contribution of plants in constructed wetlands toward actual wastewater treatment.

  14. Human mitochondrial variants influence on oxygen consumption.

    PubMed

    Marcuello, Ana; Martínez-Redondo, Diana; Dahmani, Yahya; Casajús, José A; Ruiz-Pesini, Eduardo; Montoya, Julio; López-Pérez, Manuel J; Díez-Sánchez, Carmen

    2009-02-01

    This work investigates if human mitochondrial variants influence on maximal oxygen consumption (VO(2max)). With this purpose we recruited, as a uniform population in term of nutritional habits and life style, 114 healthy male Spanish subjects that practiced fitness exercises 3-4 times a week. Once mtDNA haplogroups were determined, we found that J presents with lower VO(2max) (P=0.02) than nonJ variants. J has been related with a lower efficiency of electron transport chain (ETC), diminished ATP and ROS production. Thus, the difficult to compensate the mitochondrial energetic deficiency could explain the accumulation of J haplogroup in LHON and multiple sclerosis. Furthermore, the lower ROS production associated to J could also account for the accrual of this variant in elderly people consequent to a decreased oxidative damage.

  15. Production and Consumption of Reactive Oxygen Species by Fullerenes

    EPA Science Inventory

    Reactive oxygen species (ROS) are one of the most important intermediates in chemical, photochemical, and biological processes. To understand the environmental exposure and toxicity of fullerenes better, the production and consumption of ROS (singlet oxygen, superoxide, hydrogen ...

  16. Oxygen consumption and respiration following two yoga relaxation techniques.

    PubMed

    Telles, S; Reddy, S K; Nagendra, H R

    2000-12-01

    The present study was conducted to evaluate a statement in ancient yoga texts that suggests that a combination of both "calming" and "stimulating" measures may be especially helpful in reaching a state of mental equilibrium. Two yoga practices, one combining "calming and stimulating" measures (cyclic meditation) and the other, a "calming" technique (shavasan), were compared. The oxygen consumption, breath rate, and breath volume of 40 male volunteers (group mean +/- SD, 27.0 +/- 5.7 years) were assessed before and after sessions of cyclic meditation (CM) and before and after sessions of shavasan (SH). The 2 sessions (CM, SH) were 1 day apart. Cyclic meditation includes the practice of yoga postures interspersed with periods of supine relaxation. During SH the subject lies in a supine position throughout the practice. There was a significant decrease in the amount of oxygen consumed and in breath rate and an increase in breath volume after both types of sessions (2-factor ANOVA, paired t test). However, the magnitude of change on all 3 measures was greater after CM: (1) Oxygen consumption decreased 32.1% after CM compared with 10.1% after SH; (2) breath rate decreased 18.0% after CM and 15.2% after SH; and (3) breath volume increased 28.8% after CM and 15.9% after SH. These results support the idea that a combination of yoga postures interspersed with relaxation reduces arousal more than relaxation alone does.

  17. Simultaneous sampling of tissue oxygenation and oxygen consumption in skeletal muscle.

    PubMed

    Nugent, William H; Song, Bjorn K; Pittman, Roland N; Golub, Aleksander S

    2016-05-01

    Under physiologic conditions, microvascular oxygen delivery appears to be well matched to oxygen consumption in respiring tissues. We present a technique to measure interstitial oxygen tension (PISFO2) and oxygen consumption (VO2) under steady-state conditions, as well as during the transitions from rest to activity and back. Phosphorescence Quenching Microscopy (PQM) was employed with pneumatic compression cycling to achieve 1 to 10 Hz sampling rates of interstitial PO2 and simultaneous recurrent sampling of VO2 (3/min) in the exteriorized rat spinotrapezius muscle. The compression pressure was optimized to 120-130 mmHg without adverse effect on the tissue preparation. A cycle of 5s compression followed by 15s recovery yielded a resting VO2 of 0.98 ± 0.03 ml O2/100 cm(3)min while preserving microvascular oxygen delivery. The measurement system was then used to assess VO2 dependence on PISFO2 at rest and further tested under conditions of isometric muscle contraction to demonstrate a robust ability to monitor the on-kinetics of tissue respiration and the compensatory changes in PISFO2 during contraction and recovery. The temporal and spatial resolution of this approach is well suited to studies seeking to characterize microvascular oxygen supply and demand in thin tissues. PMID:26683232

  18. Production and consumption of reactive oxygen species by fullerenes.

    PubMed

    Kong, Lingjun; Zepp, Richard G

    2012-01-01

    Reactive oxygen species (ROS) are one of the most important intermediates in chemical, photochemical, and biological processes. To understand the environmental exposure and toxicity of fullerenes better, the production and consumption of ROS (singlet oxygen, superoxide, hydrogen peroxide, and hydroxyl radicals) by Buckminster fullerene (C(60) ) and fullerenol were investigated in aqueous systems. Fullerenol exhibits higher photoproduction efficiency of singlet oxygen and superoxide than aqueous suspensions of C(60) aggregates (aqu/nC(60) ), and this higher efficiency results in higher steady-state concentrations of these two ROS. Transmission electron microscopy indicates that the C(60) molecules in aqu/nC(60) are much more closely packed than the C(60) cages in fullerenol. These observations provide additional evidence that the lower ROS production efficiency of aqu/nC(60) is attributable primarily to efficient self-quenching of C(60) triplet states. Production of singlet oxygen by aqu/nC(60) is accelerated by increasing oxygen concentration and in part is sensitized by fluorescent photoproducts that accumulate during irradiation. The fullerenes react slowly with singlet oxygen (second-order rate constant <4 × 10(5)  M(-1)  s(-1) ), but react rapidly with hydroxyl radicals (second-order rate constants of 5.4 × 10(9) and 4 × 10(8)  M(-1)  s(-1) for aqu/nC(60) and fullerenol, respectively). These results show that environmental conditions, including light exposure and oxygen concentration, have the potential to impact the generation of toxic ROS by fullerenes.

  19. Oxygen consumption by mitochondria from an endotherm and an ectotherm.

    PubMed

    Berner, N J

    1999-09-01

    Comparisons of metabolic properties of mitochondria from an endothermic and an ectothermic vertebrate were performed. Oxygen (O2) consumption rates of liver mitochondria from laboratory mice and western fence lizard (Sceloporus occidentalis) were determined over a range of temperatures (10, 20, 30 and 37 degrees C) and in the presence of a variety of substrates. At 37 degrees C the O2 consumption rate of mouse mitochondria was 4-11 times higher than lizard mitochondria in the presence of five of eight substrates. This range of differences is similar to differences reported for O2 consumption of endothermic animals, tissues and cells over those of ectotherms. Thermal sensitivity of mitochondria was measured by calculation of Q10s for O2 consumption. Q10s were highest for mouse mitochondria overall. The range that showed the highest Q10s for the mouse mitochondria was 30-20 degrees C, whereas for the lizard mitochondria it was 20-10 degrees C. Thus, mitochondria from the ectotherm showed a lower degree of temperature sensitivity than did mitochondria from the endotherm. The preferred substrate for all mitochondria at all temperatures was succinate, but mouse mitochondria then showed some preference for alpha-ketoglutarate and citrate, whereas lizard mitochondria showed a preference for pyruvate and malate + pyruvate.

  20. Oxygen consumption by mitochondria from an endotherm and an ectotherm.

    PubMed

    Berner, N J

    1999-09-01

    Comparisons of metabolic properties of mitochondria from an endothermic and an ectothermic vertebrate were performed. Oxygen (O2) consumption rates of liver mitochondria from laboratory mice and western fence lizard (Sceloporus occidentalis) were determined over a range of temperatures (10, 20, 30 and 37 degrees C) and in the presence of a variety of substrates. At 37 degrees C the O2 consumption rate of mouse mitochondria was 4-11 times higher than lizard mitochondria in the presence of five of eight substrates. This range of differences is similar to differences reported for O2 consumption of endothermic animals, tissues and cells over those of ectotherms. Thermal sensitivity of mitochondria was measured by calculation of Q10s for O2 consumption. Q10s were highest for mouse mitochondria overall. The range that showed the highest Q10s for the mouse mitochondria was 30-20 degrees C, whereas for the lizard mitochondria it was 20-10 degrees C. Thus, mitochondria from the ectotherm showed a lower degree of temperature sensitivity than did mitochondria from the endotherm. The preferred substrate for all mitochondria at all temperatures was succinate, but mouse mitochondria then showed some preference for alpha-ketoglutarate and citrate, whereas lizard mitochondria showed a preference for pyruvate and malate + pyruvate. PMID:10582317

  1. Oxygen consumption of animals under conditions of hypokinesia

    NASA Technical Reports Server (NTRS)

    Loginova, Y. N.; Volozhin, A. I.; Krasnyku, I. G.; Stroganova, Y. A.

    1980-01-01

    The influence of hypokinesia on the oxygen consumption of rats, dog, and squirrels was investigated. Three periods of gaseous exchange were revealed in rats under conditions of a limited motor activity. During the first 10-15 days O2 consumption displayed a sharp elevation; on the 20th-30th day, it became stabilized at a higher level (in comparison with control) and it sharply rose again on the 40th-100th day. In dogs, hypokinesia produced a reduction of O2 consumption and then a tendency to its elevation was seen. A short period of physical exercises in squirrels after hypokinesia led to increased oxygen consumption at rest.

  2. Oxygen consumption and respiration during and after two yoga relaxation techniques.

    PubMed

    Sarang, Patil S; Telles, Shirley

    2006-06-01

    Cyclic meditation (CM) is a technique which combines "stimulating" and "calming" practices, based on a statement in ancient yoga texts suggesting that such a combination may be especially helpful to reach a state of mental equilibrium. The oxygen consumption, breath rate and breath volume of 50 male volunteers (group mean age+/-SD, 27+/-6.3 years) were assessed before, during, and after sessions of CM and sessions of supine rest in the corpse posture (shavasana, SH). The sessions were one day apart and the order was alternated. The oxygen consumption, breath rate and breath volume increased during the "stimulating" practices of CM, returned to the baseline during the "calming" practices, and the oxygen consumption decreased by 19.3 percent below baseline values after CM. During the SH session the oxygen consumption, breath rate and breath volume reduced; however the decrease in oxygen consumption after SH was less than after CM (i.e., 4.8 percent). The results support the idea that a combination of yoga postures with supine rest (in CM) reduces the oxygen consumption more than resting supine alone does.

  3. Oxygen consumption along bed forms under losing and gaining streamflow conditions

    NASA Astrophysics Data System (ADS)

    De Falco, Natalie; Arnon, Shai; Boano, Fulvio

    2016-04-01

    Recent studies have demonstrated that bed forms are the most significant geomorphological structure that drives hyporheic exchange and biogeochemical processes in stream networks. Other studies also demonstrated that due to the hyporheic flow patterns within bed form, biogeochemical processes do not occur uniformly along and within the bed forms. The objective of this work was to systematically evaluate how losing or gaining flow conditions affect oxygen consumption by biofilm along sandy bed forms. We measured the effects of losing and gaining flow conditions on oxygen consumption by combining modeling and experiments in a novel laboratory flume system that enable the control of losing and gaining fluxes. Oxygen consumption was measured after growing a benthic biofilm fed with Sodium Benzoate (as a carbon source) and measuring the distribution of oxygen in the streambed with microelectrodes. The experimental results were analyzed using a novel code that calculates vertical profiles of reaction rates in the presence of hyporheic water fluxes. These experimental observations and modeling revealed that oxygen distribution varied along the bed forms. The zone of oxygen consumption (i.e. depth of penetration) was the largest at the upstream side of the bed form and the smallest in the lee side (at the lowest part of the bed form), regardless of the flow conditions. Also, the zone of oxygen consumption was the largest under losing conditions, the smallest under gaining conditions, and in-between under neutral conditions. The distribution of oxygen consumption rates determined with our new model will be also discussed. Our preliminary results enable us to show the importance of the coupling between flow conditions and oxygen consumption along bed forms and are expected to improve our understanding of nutrient cycling in streams.

  4. The interaction between cutaneous and spinal therman inputs in the control of oxygen consumption in the rat.

    PubMed Central

    Banet, M; Hensel, H

    1976-01-01

    1. The effect of thermal stimulation of the spinal cord on the rate of oxygen consumption was studied in five unanaesthetized rats during exposure to various ambient temperatures. 2. In a warm environment, cooling the spinal cord had no effect on the rate of oxygen consumption but in thermoneutral and cold environments the rate of oxygen consumption increased proportionally to the intensity of spinal cooling. Heating the spinal cord decreased the level of oxygen consumption and, if intense enough, suppressed the thermoregulatory increase in metabolic rate. 3. It is concluded that, in the control of oxygen consumption in the rat, the afferent signals from thermal sensors in the spinal cord and skin are added. PMID:978543

  5. Consumption and diffusion of dissolved oxygen in sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Manaka, M.; Takeda, M.

    2016-10-01

    Fe(II)-bearing minerals (e.g., biotite, chlorite, and pyrite) are a promising reducing agent for the consumption of atmospheric oxygen in repositories for the geological disposal of high-level radioactive waste. To estimate effective diffusion coefficients (De, in m2 s- 1) for dissolved oxygen (DO) and the reaction rates for the oxidation of Fe(II)-bearing minerals in a repository environment, we conducted diffusion-chemical reaction experiments using intact rock samples of Mizunami sedimentary rock. In addition, we conducted batch experiments on the oxidation of crushed sedimentary rock by DO in a closed system. From the results of the diffusion-chemical reaction experiments, we estimated the values of De for DO to lie within the range 2.69 × 10- 11 < De < 6.30 × 10- 11. Values of the second-order rate constant (k, in L mol-1 s- 1) were in the range - 3.66 < log k < - 2.83 (from batch experiments) and in the range - 3.87 < log k < - 2.22 (from diffusion-chemical reaction experiments). Many of these values are within the range of previously published rates for reaction between O2(aq) and Fe(II) surface complexes. The average value for the total concentration of reactive sites was about 10- 4 mol m- 2 from batch experiments. In contrast, the value of reactive sites estimated from the physical surface area was about 10- 8 mol m- 2, indicating that the reaction within intact rock is limited to the sites that originally existed with accessible porosity for O2(aq). This difference arises because the batch experiments used powdered samples, meaning that new sites which formed during milling were added to the original reaction sites. On the basis of these observations and interpretations, diffusion-chemical reaction experiments make it possible to determine the values of the kinetic parameter and diffusivity for an intact rock sample simultaneously.

  6. Data on oxygen consumption rate, respiratory exchange ratio, and movement in C57BL/6J female mice on the third day of consuming a high-fat diet

    PubMed Central

    Marvyn, Phillip M.; Bradley, Ryan M.; Mardian, Emily B.; Marks, Kristin A.; Duncan, Robin E.

    2016-01-01

    Whole animal physiological measures were assessed following three days of either standard diet or high fat diet, in either the fasted or non-fasted states. Our data shows that acute 3-day high fat feeding increases whole body lipid oxidation. When this feeding protocol is followed by an overnight fast, oxygen consumption (VO2) in the light phase is reduced in both dietary groups, but oxygen consumption in the dark phase is only reduced in mice fed the high-fat diet. Furthermore, the fasting-induced rise in dark cycle activity level observed in mice maintained on a standard diet is abolished when mice are fed a high-fat diet. PMID:27014733

  7. Nisin stimulates oxygen consumption by Staphylococcus aureus and Escherichia coli.

    PubMed Central

    Carneiro de Melo, A M; Cook, G M; Miles, R J; Poole, R K

    1996-01-01

    Nisin stimulated oxygen consumption by nongrowing, glucose-metabolizing Staphylococcus aureus and Escherichia coli cells, indicating a protonophore mode of action. A similar stimulation in E. coli cells osmotically stressed to disrupt the outer cell membrane confirmed the cytoplasmic membrane as the site of nisin action and showed that nisin uptake was not prevented by the outer membrane. PMID:8633884

  8. The effect of exogenous zinc ions on the pattern of oxygen consumption of the hepatic mitochondria of albino rats.

    PubMed

    Kukoyi, B I; Costello, L C; Franklin, R B

    2004-12-01

    The effect of incubation of coupled liver mitochondria on varying concentration of zinc ion was determined. A low concentration of 6 microM zinc ion was found to inhibit the rate of oxygen consumption of the liver mitochondria significantly [P < 0.01]. There was uncoupling of the liver mitochondria when subjected to varying incubation periods. There was no change observed in the control experiment. Zinc-citrate inhibited the rate of oxygen consumption significantly [P < 0.01] when compare with the control. The changes observed in the Zn-aspartate were insignificant. Zn-EDTA had no inhibitory or stimulatory effect on the rate of liver mitochondrial oxygen consumption.

  9. Oxygen Consumption of Tilapia and Preliminary Mass Flows through a Prototype Closed Aquaculture System

    NASA Technical Reports Server (NTRS)

    Muller, Matthew S.; Bauer, Clarence F.

    1994-01-01

    Performance of NASA's prototype CELSS Breadboard Project Closed Aquaculture System was evaluated by estimating gas exchange quantification and preliminary carbon and nitrogen balances. The total system oxygen consumption rate was 535 mg/hr kg/fish (cv = 30%) when stocked with Tilapia aurea populations (fresh weights of 97 +/- 19 to 147 +/- 36 g/fish for various trials). Oxygen consumption by T. aurea (260 mg/hr kg/fish) contributed to approximately one-half of total system demand. Continuous carbon dioxide quantification methods were analyzed using the,relation of carbon dioxide to oxygen consumption. Overall food conversion rates averaged 18.2 +/- 3.2%. Major pathways for nitrogen and carbon in the system were described with preliminary mass closure of 60-80% and 60% for nitrogen and carbon.

  10. Effects of Dental Methacrylates on Oxygen Consumption and Redox Status of Human Pulp Cells

    PubMed Central

    Nocca, Giuseppina; Callà, Cinzia; Martorana, Giuseppe Ettore; Cicillini, Loredana; Lupi, Alessandro; Cordaro, Massimo; Luisa Gozzo, Maria

    2014-01-01

    Several studies have already demonstrated that the incomplete polymerization of resin-based dental materials causes the release of monomers which might affect cell metabolism. The aim of this study was to investigate the effects of triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, urethane dimethacrylate, and 2-hydroxyethyl methacrylate on (1) cellular energy metabolism, evaluating oxygen consumption rate, glucose consumption, glucose 6-phosphate dehydrogenase activity, and lactate production, and (2) cellular redox status, through the evaluation of glutathione concentration and of the activities of enzymes regulating glutathione metabolism. Methods. Human pulp cells were used and oxygen consumption was measured by means of a Clark electrode. Moreover, reactive oxygen species production was quantified. Enzymatic activity and glucose and lactate concentrations were determined through a specific kit. Results. Triethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and 2-hydroxyethyl methacrylate induced a decrease in oxygen consumption rate, an enhancement of glucose consumption, and lactate production, whilst glucose 6-phosphate dehydrogenase and glutathione reductase activity were not significantly modified. Moreover, the monomers induced an increase of reactive oxygen species production with a consequent increase of superoxide dismutase and catalase enzymatic activities. A depletion of both reduced and total glutathione was also observed. Conclusion. The obtained results indicate that dental monomers might alter energy metabolism and glutathione redox balance in human pulp cells. PMID:24693541

  11. Renal transplantation induces mitochondrial uncoupling, increased kidney oxygen consumption, and decreased kidney oxygen tension.

    PubMed

    Papazova, Diana A; Friederich-Persson, Malou; Joles, Jaap A; Verhaar, Marianne C

    2015-01-01

    Hypoxia is an acknowledged pathway to renal injury and ischemia-reperfusion (I/R) and is known to reduce renal oxygen tension (Po2). We hypothesized that renal I/R increases oxidative damage and induces mitochondrial uncoupling, resulting in increased oxygen consumption and hence kidney hypoxia. Lewis rats underwent syngenic renal transplantation (TX) and contralateral nephrectomy. Controls were uninephrectomized (1K-CON) or left untreated (2K-CON). After 7 days, urinary excretion of protein and thiobarbituric acid-reactive substances were measured, and after 14 days glomerular filtration rate (GFR), renal blood flow, whole kidney Qo2, cortical Po2, kidney cortex mitochondrial uncoupling, renal oxidative damage, and tubulointerstitial injury were assessed. TX, compared with 1K-CON, resulted in mitochondrial uncoupling mediated via uncoupling protein-2 (16 ± 3.3 vs. 0.9 ± 0.4 pmol O2 · s(-1)· mg protein(-1), P < 0.05) and increased whole kidney Qo2 (55 ± 16 vs. 33 ± 10 μmol O2/min, P < 0.05). Corticomedullary Po2 was lower in TX compared with 1K-CON (30 ± 13 vs. 47 ± 4 μM, P < 0.05) whereas no significant difference was observed between 2K-CON and 1K-CON rats. Proteinuria, oxidative damage, and the tubulointerstitial injury score were not significantly different in 1K-CON and TX. Treatment of donors for 5 days with mito-TEMPO reduced mitochondrial uncoupling but did not affect renal hemodynamics, Qo2, Po2, or injury. Collectively, our results demonstrate increased mitochondrial uncoupling as an early event after experimental renal transplantation associated with increased oxygen consumption and kidney hypoxia in the absence of increases in markers of damage.

  12. Aerobic composting of waste activated sludge: Kinetic analysis for microbiological reaction and oxygen consumption

    SciTech Connect

    Yamada, Y.; Kawase, Y. . E-mail: bckawase@mail.eng.toyo.ac.jp

    2006-07-01

    In order to examine the optimal design and operating parameters, kinetics for microbiological reaction and oxygen consumption in composting of waste activated sludge were quantitatively examined. A series of experiments was conducted to discuss the optimal operating parameters for aerobic composting of waste activated sludge obtained from Kawagoe City Wastewater Treatment Plant (Saitama, Japan) using 4 and 20 L laboratory scale bioreactors. Aeration rate, compositions of compost mixture and height of compost pile were investigated as main design and operating parameters. The optimal aerobic composting of waste activated sludge was found at the aeration rate of 2.0 L/min/kg (initial composting mixture dry weight). A compost pile up to 0.5 m could be operated effectively. A simple model for composting of waste activated sludge in a composting reactor was developed by assuming that a solid phase of compost mixture is well mixed and the kinetics for microbiological reaction is represented by a Monod-type equation. The model predictions could fit the experimental data for decomposition of waste activated sludge with an average deviation of 2.14%. Oxygen consumption during composting was also examined using a simplified model in which the oxygen consumption was represented by a Monod-type equation and the axial distribution of oxygen concentration in the composting pile was described by a plug-flow model. The predictions could satisfactorily simulate the experiment results for the average maximum oxygen consumption rate during aerobic composting with an average deviation of 7.4%.

  13. Heat flux and oxygen consumption of the pregnant uterus.

    PubMed

    Rudelstorfer, R; Tabsh, K; Khoury, A; Nuwayhid, B; Brinkman, C R; Assali, N S

    1986-02-01

    Heat flux (conductive and convective heat) and oxygen consumption of the pregnant uterus and its content were measured simultaneously in the same group of pregnant ewes during the acute postoperative period, during a chronic resting period, and during alpha- and beta-adrenergic-receptor stimulation with norepinephrine and ritodrine. Results indicated four conclusions. First, an excellent correlation existed between heat flux and oxygen consumption in the acute and chronic resting condition as well as during increasing uteroplacental vascular resistance and decreasing blood flow produced by norepinephrine infusion; the correlation was not as good during ritodrine infusion. Second, during rest, about 85% of heat generated by the pregnant uterus is eliminated through the uteroplacental circulation while the remaining heat diffuses through the myometrium. Third, during decreasing uteroplacental blood flow and elevated resistance, the pregnant uterus is able to maintain a normal thermostasis by widening the temperature difference in the blood entering and leaving the uterus and by increasing the myometrial heat exchange; oxygen consumption also is maintained at normal level through increase in oxygen extraction. Fourth, with the exception of uteroplacental circulation, the circulatory, metabolic, and thermal conditions of the pregnant ewe are not different after 5 hours from 5 to 7 days after the surgical procedure. PMID:3004223

  14. Thermodynamics of the heart: Relation between cardiac output and oxygen consumption

    NASA Astrophysics Data System (ADS)

    Uehara, Mituo; Sakane, Kumiko K.; Bertolotti, Simone A.

    2008-06-01

    A thermodynamic approach is used to derive a relation between cardiac output and rate of oxygen consumption. As an example, the relation is used to calculate the cardiac output of a young woman exercising on a treadmill. The results can be understood by undergraduates without any previous knowledge of human physiology.

  15. Effects of cadmium chloride on oxygen consumption and gill morphology of Indian flying barb, Esomus danricus.

    PubMed

    Das, Suchismita; Gupta, Abhik

    2012-11-01

    Effects of three sub lethal concentrations of cadmium chloride (0.636, 0.063 and 0.006 mg l(-1)) on oxygen consumption and gill morphology in Indian flying barb, Esomus danricus (Hamilton-Buchanan), a teleost fish, were studied. When compared to control, 0.636 mg l(-1) of cadmium chloride after 7,14, 21 and 28 day exposure showed a significant decline in rates of oxygen consumption at 32.98, 28.40, 23.88 and 21.69 ml hr(1) 100 g(-1) of tissue, respectively; while, 0.063 mg l(-1) of cadmium chloride for the same exposure durations showed a significant decline in rates of oxygen consumption at 34.28, 29.30, 28.05 and 26.47 ml hr(1)100 g(-1) of tissue, respectively. However, significant decline in the rate of oxygen consumption at 0.006 mg l(-1) of cadmium chloride could be observed from 21st day of exposure. Gill tissue showed various histopathological changes including epithelial lifting, hyperplasia, mucous secretion, marked leucocyte infiltration in the epithelium after 28 days of cadmium chloride exposure.

  16. Effects of cadmium chloride on oxygen consumption and gill morphology of Indian flying barb, Esomus danricus.

    PubMed

    Das, Suchismita; Gupta, Abhik

    2012-11-01

    Effects of three sub lethal concentrations of cadmium chloride (0.636, 0.063 and 0.006 mg l(-1)) on oxygen consumption and gill morphology in Indian flying barb, Esomus danricus (Hamilton-Buchanan), a teleost fish, were studied. When compared to control, 0.636 mg l(-1) of cadmium chloride after 7,14, 21 and 28 day exposure showed a significant decline in rates of oxygen consumption at 32.98, 28.40, 23.88 and 21.69 ml hr(1) 100 g(-1) of tissue, respectively; while, 0.063 mg l(-1) of cadmium chloride for the same exposure durations showed a significant decline in rates of oxygen consumption at 34.28, 29.30, 28.05 and 26.47 ml hr(1)100 g(-1) of tissue, respectively. However, significant decline in the rate of oxygen consumption at 0.006 mg l(-1) of cadmium chloride could be observed from 21st day of exposure. Gill tissue showed various histopathological changes including epithelial lifting, hyperplasia, mucous secretion, marked leucocyte infiltration in the epithelium after 28 days of cadmium chloride exposure. PMID:23741801

  17. [Management of oxygen delivery and consumption during sepsis].

    PubMed

    Regueira, Tomas; Andresen, Max

    2010-02-01

    Maintaining an adequate tissue oxygen delivery (DO(2)) and consumption (VO(2)) is crucial in the treatment of septic patients. A fall in V0(2) is associated with a higher mortality. The early recognition of shock or tissue hypo perfusion impacts on patient prognosis. In occasions, hypovolemia or important regional oxygen debts are not recognized, since macro homodynamic variables have been compensated. In this situation, the use of metabolic hypo perfusion markers such as lactate, central venous oxygen saturation and gastric goniometry, can be helpful. However, interpretation of these markers should be cautious and always considering the overall clinical status of the patient. In the initial stages of sepsis, the dependency of V0(2) on DO(2) predominates as histopathological mechanism of multiple organic failure. In late stages, other factors predominate as determinants of multiple organic failure and mortality, such as hyper or hypo immune response, microcirculatory alterations and cytopathic hypoxia.

  18. Variation in the link between oxygen consumption and ATP production, and its relevance for animal performance

    PubMed Central

    Salin, Karine; Auer, Sonya K.; Rey, Benjamin; Selman, Colin; Metcalfe, Neil B.

    2015-01-01

    It is often assumed that an animal's metabolic rate can be estimated through measuring the whole-organism oxygen consumption rate. However, oxygen consumption alone is unlikely to be a sufficient marker of energy metabolism in many situations. This is due to the inherent variability in the link between oxidation and phosphorylation; that is, the amount of adenosine triphosphate (ATP) generated per molecule of oxygen consumed by mitochondria (P/O ratio). In this article, we describe how the P/O ratio can vary within and among individuals, and in response to a number of environmental parameters, including diet and temperature. As the P/O ratio affects the efficiency of cellular energy production, its variability may have significant consequences for animal performance, such as growth rate and reproductive output. We explore the adaptive significance of such variability and hypothesize that while a reduction in the P/O ratio is energetically costly, it may be associated with advantages in terms of somatic maintenance through reduced production of reactive oxygen species. Finally, we discuss how considering variation in mitochondrial efficiency, together with whole-organism oxygen consumption, can permit a better understanding of the relationship between energy metabolism and life history for studies in evolutionary ecology. PMID:26203001

  19. MODELING ENERGY EXPENDITURE AND OXYGEN CONSUMPTION IN HUMAN EXPOSURE MODELS: ACCOUNTING FOR FATIGUE AND EPOC

    EPA Science Inventory

    Human exposure and dose models often require a quantification of oxygen consumption for a simulated individual. Oxygen consumption is dependent on the modeled Individual's physical activity level as described in an activity diary. Activity level is quantified via standardized val...

  20. Rebreathing method for the simultaneous measurement of oxygen consumption and effective pulmonary blood flow during exercise.

    PubMed

    Bush, A; Busst, C M; Johnson, S; Denison, D M

    1988-04-01

    This paper describes a rebreathing method for the simultaneous measurement of oxygen consumption (VO2) and effective pulmonary blood flow (QP. eff) at rest and during exercise. Subjects rebreathed a test gas consisting of 35% oxygen, 3.5% chlorodifluoromethane (freon-22), and 10% argon in nitrogen for 30 seconds or until the respired oxygen tension fell to below 13.3 kPa. Sixty normal subjects were studied on a motorized treadmill, the Bruce protocol being used. The rebreathing manoeuvre was performed at three minute intervals, and was initially practised sitting down. Measurements were then made with the subjects standing at rest, and subsequently during the last minute of each stage of the Bruce exercise protocol until the subjects were exhausted. Heart rate was recorded from the electrocardiogram. Oxygen uptake plotted against calculated power (watts) showed a discontinuity between resting and exercise values, probably because power output during treadmill exercise is underestimated. The arbitrary addition of 30 watts to the exercise power output abolished this discontinuity. There was good agreement between rebreathing estimates of oxygen consumption and values measured during a second exercise test by the conventional open circuit argon dilution method. Coefficients of variation of oxygen consumption and effective pulmonary blood flow measured by rebreathing were usually less than 10% even during maximal exertion. At rest mean (SD) effective pulmonary blood flow corrected for body surface area was 2.2 (0.46) l/min/m2. Effective pulmonary blood flow rose linearly with oxygen consumption. At rest the arteriovenous oxygen content difference for pulmonary blood (VO2/QP eff) was 9.1 (1.6) ml/dl, rising to a maximum of 16.4 (1.8) ml/dl. The stroke volume index was 27.5 (6.8) ml/m2, rising to a maximum of 46.5 (7.1) ml/m2 during exertion.

  1. Rebreathing method for the simultaneous measurement of oxygen consumption and effective pulmonary blood flow during exercise.

    PubMed Central

    Bush, A; Busst, C M; Johnson, S; Denison, D M

    1988-01-01

    This paper describes a rebreathing method for the simultaneous measurement of oxygen consumption (VO2) and effective pulmonary blood flow (QP. eff) at rest and during exercise. Subjects rebreathed a test gas consisting of 35% oxygen, 3.5% chlorodifluoromethane (freon-22), and 10% argon in nitrogen for 30 seconds or until the respired oxygen tension fell to below 13.3 kPa. Sixty normal subjects were studied on a motorized treadmill, the Bruce protocol being used. The rebreathing manoeuvre was performed at three minute intervals, and was initially practised sitting down. Measurements were then made with the subjects standing at rest, and subsequently during the last minute of each stage of the Bruce exercise protocol until the subjects were exhausted. Heart rate was recorded from the electrocardiogram. Oxygen uptake plotted against calculated power (watts) showed a discontinuity between resting and exercise values, probably because power output during treadmill exercise is underestimated. The arbitrary addition of 30 watts to the exercise power output abolished this discontinuity. There was good agreement between rebreathing estimates of oxygen consumption and values measured during a second exercise test by the conventional open circuit argon dilution method. Coefficients of variation of oxygen consumption and effective pulmonary blood flow measured by rebreathing were usually less than 10% even during maximal exertion. At rest mean (SD) effective pulmonary blood flow corrected for body surface area was 2.2 (0.46) l/min/m2. Effective pulmonary blood flow rose linearly with oxygen consumption. At rest the arteriovenous oxygen content difference for pulmonary blood (VO2/QP eff) was 9.1 (1.6) ml/dl, rising to a maximum of 16.4 (1.8) ml/dl. The stroke volume index was 27.5 (6.8) ml/m2, rising to a maximum of 46.5 (7.1) ml/m2 during exertion. PMID:3406913

  2. A cellular isolation system for real-time single-cell oxygen consumption monitoring

    PubMed Central

    Dragavon, Joe; Molter, Tim; Young, Cody; Strovas, Tim; McQuaide, Sarah; Holl, Mark; Zhang, Meng; Cookson, Brad; Jen, Alex; Lidstrom, Mary; Meldrum, Deirdre; Burgess, Lloyd

    2008-01-01

    The development of a cellular isolation system (CIS) that enables the monitoring of single-cell oxygen consumption rates in real time is presented. The CIS was developed through a multidisciplinary effort within the Microscale Life Sciences Center (MLSC) at the University of Washington. The system comprises arrays of microwells containing Pt-porphyrin-embedded polystyrene microspheres as the reporter chemistry, a lid actuator system and a gated intensified imaging camera, all mounted on a temperature-stabilized confocal microscope platform. Oxygen consumption determination experiments were performed on RAW264.7 mouse macrophage cells as proof of principle. Repeatable and consistent measurements indicate that the oxygen measurements did not adversely affect the physiological state of the cells measured. The observation of physiological rates in real time allows studies of cell-to-cell heterogeneity in oxygen consumption rate to be performed. Such studies have implications in understanding the role of mitochondrial function in the progression of inflammatory-based diseases, and in diagnosing and treating such diseases. PMID:18522927

  3. Role of macroscopic particles in deep-sea oxygen consumption.

    PubMed

    Bochdansky, Alexander B; van Aken, Hendrik M; Herndl, Gerhard J

    2010-05-01

    Macroscopic particles (>500 mum), including marine snow, large migrating zooplankton, and their fast-sinking fecal pellets, represent primary vehicles of organic carbon flux from the surface to the deep sea. In contrast, freely suspended microscopic particles such as bacteria and protists do not sink, and they contribute the largest portion of metabolism in the upper ocean. In bathy- and abyssopelagic layers of the ocean (2,000-6,000 m), however, microscopic particles may not dominate oxygen consumption. In a section across the tropical Atlantic, we show that macroscopic particle peaks occurred frequently in the deep sea, whereas microscopic particles were barely detectable. In 10 of 17 deep-sea profiles (>2,000 m depth), macroscopic particle abundances were more strongly cross-correlated with oxygen deficits than microscopic particles, suggesting that biomass bound to large particles dominates overall deep-sea metabolism.

  4. Maximal oxygen consumption in healthy humans: theories and facts.

    PubMed

    Ferretti, Guido

    2014-10-01

    This article reviews the concept of maximal oxygen consumption ([Formula: see text]) from the perspective of multifactorial models of [Formula: see text] limitation. First, I discuss procedural aspects of [Formula: see text] measurement: the implications of ramp protocols are analysed within the theoretical work of Morton. Then I analyse the descriptive physiology of [Formula: see text], evidencing the path that led to the view of monofactorial cardiovascular or muscular [Formula: see text] limitation. Multifactorial models, generated by the theoretical work of di Prampero and Wagner around the oxygen conductance equation, represented a radical change of perspective. These models are presented in detail and criticized with respect to the ensuing experimental work. A synthesis between them is proposed, demonstrating how much these models coincide and converge on the same conclusions. Finally, I discuss the cases of hypoxia and bed rest, the former as an example of the pervasive effects of the shape of the oxygen equilibrium curve, the latter as a neat example of adaptive changes concerning the entire respiratory system. The conclusion is that the concept of cardiovascular [Formula: see text] limitation is reinforced by multifactorial models, since cardiovascular oxygen transport provides most of the [Formula: see text] limitation, at least in normoxia. However, the same models show that the role of peripheral resistances is significant and cannot be neglected. The role of peripheral factors is greater the smaller is the active muscle mass. In hypoxia, the intervention of lung resistances as limiting factors restricts the role played by cardiovascular and peripheral factors.

  5. Daily cycle in oxygen consumption by the sea anemone Nematostella vectensis Stephenson.

    PubMed

    Maas, Amy E; Jones, Ian T; Reitzel, Adam M; Tarrant, Ann M

    2016-01-01

    In bilaterian animals, the circadian clock is intimately involved in regulating energetic metabolism. Although cnidarians exhibit diel behavioral rhythms including cycles in locomotor activity, tentacle extension and spawning, daily cycles in cnidarian metabolism have not been described. To explore a possible circadian metabolic cycle, we maintained the anemone Nematostella vectensis in a 12 h light/dark cycle, a reversed light cycle, or in constant darkness. Oxygen consumption rates were measured at intervals using an optical oxygen meter. Respiration rates responded to entrainment with higher rates during light periods. During a second experiment with higher temporal resolution, respiration rates peaked late in the light period. The diel pattern could be detected after six days in constant darkness. Together, our results suggest that respiration rates in Nematostella exhibit a daily cycle that may be under circadian control and that the cycle in respiration rate is not driven by the previously described nocturnal increase in locomotor activity in this species. PMID:26772201

  6. Daily cycle in oxygen consumption by the sea anemone Nematostella vectensis Stephenson

    PubMed Central

    Maas, Amy E.; Jones, Ian T.; Reitzel, Adam M.; Tarrant, Ann M.

    2016-01-01

    ABSTRACT In bilaterian animals, the circadian clock is intimately involved in regulating energetic metabolism. Although cnidarians exhibit diel behavioral rhythms including cycles in locomotor activity, tentacle extension and spawning, daily cycles in cnidarian metabolism have not been described. To explore a possible circadian metabolic cycle, we maintained the anemone Nematostella vectensis in a 12 h light/dark cycle, a reversed light cycle, or in constant darkness. Oxygen consumption rates were measured at intervals using an optical oxygen meter. Respiration rates responded to entrainment with higher rates during light periods. During a second experiment with higher temporal resolution, respiration rates peaked late in the light period. The diel pattern could be detected after six days in constant darkness. Together, our results suggest that respiration rates in Nematostella exhibit a daily cycle that may be under circadian control and that the cycle in respiration rate is not driven by the previously described nocturnal increase in locomotor activity in this species. PMID:26772201

  7. Alcohol consumption and rates of personal violence (suicide and homicide).

    PubMed

    Lester, D

    1989-12-01

    The present study examined the association between alcohol consumption and rates of personal violence (suicide and homicide) over regions within a nation. Although suicide rates were higher in regions with a higher per capital consumption of alcohol, other social variables were also found to be associated with both alcohol consumption and suicide rates, such as divorce rates and inter-region migration. Thus, it appears that alcohol consumption may be but one index of a broader sociocultural dimension that is associated with regional rates of suicidal behavior.

  8. Prediction of Maximum Oxygen Consumption from Walking, Jogging, or Running.

    ERIC Educational Resources Information Center

    Larsen, Gary E.; George, James D.; Alexander, Jeffrey L.; Fellingham, Gilbert W.; Aldana, Steve G.; Parcell, Allen C.

    2002-01-01

    Developed a cardiorespiratory endurance test that retained the inherent advantages of submaximal testing while eliminating reliance on heart rate measurement in predicting maximum oxygen uptake (VO2max). College students completed three exercise tests. The 1.5-mile endurance test predicted VO2max from submaximal exercise without requiring heart…

  9. [Changes in oxygen consumption of basketball players during recovery after maximal load].

    PubMed

    Gocentas, Audrius; Andziulis, Artūras

    2004-01-01

    The purpose of this study was to determine the recovery period of basketball players after maximal load. Thirteen male subjects, aged 19-26 years, took part in this study. They performed an incremental cardiopulmonary test using an electronically braked bike ERGOLINE 9000. Ventilation and gas exchange were assessed and measured by breath-to-breath method using VMAX229 metabolic card and Sensor Medics gas flow analyzer. Heart rate parameters were established during continuous ECG monitoring and analysis integrated VMAX and Marquette 3.01 system. Quantitative changes of heart rate, oxygen consumption, double rate product, respiratory quotient, and metabolic equivalent were calculated or established by VMAX application algorithm. A recovery was defined through such parameters: T(HR90%)(time needed for 90% heart rate decreasing from heart rate maximum), T(HR90)(time needed for heart rate decreasing to 90 bpm), T(DPR90%)(time needed for 90% decreasing from a maximal double rate product), T(VO290%)(time needed for 90% decreasing from maximal oxygen consumption), T(RQ90%)(time needed for 90% decreasing from peak respiratory quotient), T(RQ0.9)(time needed for respiratory quotient normalization to 0.9 - to a standard value). Full recovery after maximal load was too long and completed during 1200 s, but some processes were completed earlier (lactic acid buffering within 95 s, oxygen requirement within 620 s, and normalization of heart action within 730 s). Further research is needed to explain this peculiarity of recovery.

  10. Effect of Feeding-Fasting Cycles on Oxygen Consumption and Bioenergetics of Yellow Perch

    USGS Publications Warehouse

    Chipps, Steven R.; Travis W. Schaeffer,; Daniel E. Spengler,; Casey W. Schoenebeck,; Michael L. Brown,

    2012-01-01

    We measured growth and oxygen consumption of age-1 yellow perch Perca flavescenssubjected to ad libitum (control) or variable feeding cycles of 2 (i.e., 2 d of feed, 2 d of deprivation), 6, or 12 d for a 72-d period. Individual, female yellow perch (initial weight = 51.9 ± 0.9 g [mean ± SE]) were stocked in 110-L aquaria to provide six replicates per treatment and fed measured rations of live fathead minnow Pimephales promelas. Consumption, absolute growth rate, growth efficiency, and oxygen consumption were similar among feeding regimens. However, growth trajectories for fish on the 2-d cycle were significantly lower than other feed–fast cycles. Hyperphagia occurred in all treatments. Bioenergetics model simulations indicated that consumption was significantly underestimated (t = 5.4, df = 4, P = 0.006), while growth was overestimated (t = −5.5, df = 4, P = 0.005) for fish on the 12-d cycle. However, model errors detected between observed and predicted values were low, ranging from −10.1% to +7.8%. We found that juvenile yellow perch exhibited compensatory growth (CG), but none of the feed–fast treatments resulted in growth overcompensation. Likewise, we found no evidence that respiration rates varied with CG, implying that yellow perch bioenergetics models could be used to predict the effects of feeding history and CG response on food consumption and fish growth.

  11. Theophylline increases oxygen consumption during inspiratory resistive loading.

    PubMed

    Janssens, S; Derom, E; Vanhaecke, J; Decramer, M

    1995-04-01

    The effect of theophylline on diaphragmatic blood flow (Qdi) and oxygen consumption (VO2di) was studied in eight lightly anesthetized dogs during quiet breathing and inspiratory resistive loading. Qdi was determined with the radioactive microsphere tracer technique, and VO2di was calculated as the product of Qdi and the diaphragmatic arterio-venous oxygen difference. During quiet breathing, theophylline increased minute ventilation (9.3 +/- 1.7 versus 5.1 +/- 0.4 L/min), mean inspiratory flow (547 +/- 60 versus 378 +/- 56 ml/s), and duty cycle (0.270 +/- 0.042 versus 0.192 +/- 0.024) but did not significantly alter Qdi or VO2di. Conversely, Qdi increased significantly during loaded breathing compared with quiet breathing (37 +/- 4 versus 27 +/- 3 ml/100 g/min) and was further increased by theophylline (45 +/- 7 ml/100 g/min). Theophylline did not alter the tension-time index of the diaphragm (TTdi) during inspiratory resistive loading (0.054 +/- 0.006 versus 0.056 +/- 0.004, p NS) but resulted in a disproportionate and significant increase in VO2di (2.66 +/- 0.53 versus 1.78 +/- 0.26 ml/100 g/min). Similarly, total-body oxygen consumption (VO2TB) during inspiratory loading increased significantly after theophylline (24%), but the tension-time index of the inspiratory muscles (TTi), a measure of the total respiratory load, was unchanged. We conclude that theophylline significantly increases VO2di and VO2TB at the same TTdi and TTi during resistive loading. This enhanced energy expenditure needs consideration in the clinical management of pulmonary disorders that increase the work of breathing. PMID:7697222

  12. Dynamics of oxygen supply and consumption during mainstream large-scale composting in China.

    PubMed

    Zeng, Jianfei; Shen, Xiuli; Han, Lujia; Huang, Guangqun

    2016-11-01

    This study characterized some physicochemical and biological parameters to systematically evaluate the dynamics of oxygen supply and consumption during large-scale trough composting in China. The results showed that long active phases, low maximum temperatures, low organic matter losses and high pore methane concentrations were observed in different composting layers. Pore oxygen concentrations in the top, middle and bottom layers maintained <5vol.% for 40, 42 and 45days, respectively, which accounted for more than 89% of the whole period. After each mechanical turning, oxygen was consumed at a stable respiration rate to a concentration of 5vol.% in no more than 99min and remained anaerobic in the subsequent static condition. The daily percentage of time under aerobic condition was no more than 14% of a single day. Therefore, improving FAS, adjusting aeration interval or combining turning with forced aeration was suggested to provide sufficient oxygen during composting. PMID:27566518

  13. Matching of postcontraction perfusion to oxygen consumption across submaximal contraction intensities in exercising humans

    PubMed Central

    Elder, Christopher P.; Donahue, Manus J.; Damon, Bruce M.

    2015-01-01

    Studying the magnitude and kinetics of blood flow, oxygen extraction, and oxygen consumption at exercise onset and during the recovery from exercise can lead to insights into both the normal control of metabolism and blood flow and the disturbances to these processes in metabolic and cardiovascular diseases. The purpose of this study was to examine the on- and off-kinetics for oxygen delivery, extraction, and consumption as functions of submaximal contraction intensity. Eight healthy subjects performed four 1-min isometric dorsiflexion contractions, with two at 20% MVC and two at 40% MVC. During one contraction at each intensity, relative perfusion changes were measured by using arterial spin labeling, and the deoxyhemoglobin percentage (%HHb) was estimated using the spin- and gradient-echo sequence and a previously published empirical calibration. For the whole group, the mean perfusion did not increase during contraction. The %HHb increased from ∼28 to 38% during contractions of each intensity, with kinetics well described by an exponential function and mean response times (MRTs) of 22.7 and 21.6 s for 20 and 40% MVC, respectively. Following contraction, perfusion increased ∼2.5-fold. The %HHb, oxygen consumption, and perfusion returned to precontraction levels with MRTs of 27.5, 46.4, and 50.0 s, respectively (20% MVC), and 29.2, 75.3, and 86.0 s, respectively (40% MVC). These data demonstrate in human subjects the varied recovery rates of perfusion and oxygen consumption, along with the similar rates of %HHb recovery, across these exercise intensities. PMID:26066829

  14. Matching of postcontraction perfusion to oxygen consumption across submaximal contraction intensities in exercising humans.

    PubMed

    Buck, Amanda K W; Elder, Christopher P; Donahue, Manus J; Damon, Bruce M

    2015-08-01

    Studying the magnitude and kinetics of blood flow, oxygen extraction, and oxygen consumption at exercise onset and during the recovery from exercise can lead to insights into both the normal control of metabolism and blood flow and the disturbances to these processes in metabolic and cardiovascular diseases. The purpose of this study was to examine the on- and off-kinetics for oxygen delivery, extraction, and consumption as functions of submaximal contraction intensity. Eight healthy subjects performed four 1-min isometric dorsiflexion contractions, with two at 20% MVC and two at 40% MVC. During one contraction at each intensity, relative perfusion changes were measured by using arterial spin labeling, and the deoxyhemoglobin percentage (%HHb) was estimated using the spin- and gradient-echo sequence and a previously published empirical calibration. For the whole group, the mean perfusion did not increase during contraction. The %HHb increased from ∼28 to 38% during contractions of each intensity, with kinetics well described by an exponential function and mean response times (MRTs) of 22.7 and 21.6 s for 20 and 40% MVC, respectively. Following contraction, perfusion increased ∼2.5-fold. The %HHb, oxygen consumption, and perfusion returned to precontraction levels with MRTs of 27.5, 46.4, and 50.0 s, respectively (20% MVC), and 29.2, 75.3, and 86.0 s, respectively (40% MVC). These data demonstrate in human subjects the varied recovery rates of perfusion and oxygen consumption, along with the similar rates of %HHb recovery, across these exercise intensities.

  15. Analysis of photochemical oxygen consumption effects in photodynamic therapy (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Foster, Thomas H.; Gibson, Scott L.; Gao, Yongli; Hilf, Russell

    1992-06-01

    Type II photo-oxidation depends on and consumes oxygen. Several factors, including the concentration of photosensitizer and the radiation fluence rate, determine the rate of oxygen consumption in tissue undergoing Photodynamic Therapy. If the tissue capillary density is sparse, as it is in many human tumors, our calculations indicate that for cells sufficiently distant from the nearest capillary, fluence rates commonly used in PDT (50 - 200 mW/cm2) deplete 3O2 levels below those necessary for 1O2 formation. The calculations suggest that under these conditions reduced fluence rates and radiation dose fractionation should be more effective than continuous radiation at high fluence rates in producing 1O2 throughout the treated tissue volume. These predictions are supported by results obtained in vivo. The data and their interpretation have implications for PDT dosimetry and offer the possibility of improved therapeutic ratio.

  16. [Effect of local sustained stress on general oxygen consumption in belt conveyer workers].

    PubMed

    Nakamura, E; Taguchi, S; Fujiki, Y; Kanetaka, A; Nagata, H

    1984-09-01

    The modern mechanization and rationalization of production procedures have recently reduced the intensity of work in most factories. However, it has been pointed out that monotonous inactive work and/or co-operative work can in some sense impose stronger mental and physical stresses which may induce ill health in workers. In this study, assuming the assembly and adjustment of videotape-recorders on a belt conveyor to be representative of monotonous inactive and co-operative work, changes in oxygen consumption, heart rate, blood pressure, body temperature, critical flicker fusion and subjective symptoms of fatigue throughout a workday have been followed for six female workers engaged in this type of work. The main results obtained were as follows: The average oxygen consumption of six workers was 230 ml/min, almost unchanged during the work. The belt conveyor work indicated the metabolic rate of 0.3 in terms of relative metabolic rate. The net daily energy expenditure due to the work was only about 100 kcal. The average heart rate during assembly and adjustment were respectively, about 1.4 and 1.2 times the average heart rate at rest. The blood pressure and the rate of oxygen removal increased slightly as the work progressed in assembly work, but did not increase at all in adjustment work. The critical flicker fusion and body temperature showed little change during the work.

  17. Validation of manometric microrespirometers for measuring oxygen consumption in small arthropods

    PubMed Central

    Melvin, Richard G.; Ballard, J. William O.; Williams, Joseph B.

    2008-01-01

    Scientists have used numerous techniques to measure organismal metabolic rate, including assays of oxygen (O2) consumption and carbon dioxide (CO2) production. Relatively few studies have directly compared estimates of metabolic rate on the same groups of animals as determined by different assay methods. This study directly compared measures of the metabolic rate of three lines of Drosophila simulans as determined either from direct measures of CO2 production using infrared gas analysis (IRGA), or from estimates of O2 consumption based on manometeric techniques. Determinations of metabolic rate of the same cohorts of flies using these two methods produced results that often differed widely. Typically metabolic rate as determined by the manometric method was significantly greater than that determined by CO2 output. These differences are difficult to explain by simple biotic or abiotic factor/s. Because of the idiosyncratic nature of these differences it is not possible to use a simple factor to convert from metabolic rate measurements done using manometric techniques to those expected from direct measures of CO2 output or O2 consumption. Although manometric devices are simple to construct and use, measurements of metabolic rate made with this method can vary significantly from measurements made by directly assaying CO2 production or O2 consumption. PMID:18606168

  18. Muscle Oxygen Uptake Differs from Consumption Dynamics During Transients in Exercise

    PubMed Central

    Lai, Nicola; Syed, Nakisha; Saidel, Gerald M.; Cabrera, Marco E.

    2013-01-01

    Relating external to internal respiration during exercise requires quantitative modeling analysis for reliable inferences with respect to metabolic rate. Often, oxygen transport and metabolism based on steady-state mass balances (Fick principle) and passive diffusion between blood and tissue are applied to link pulmonary to cellular respiration. Indeed, when the work rate does not change rapidly, a quasi-steady-state analysis based on the Fick principle is sufficient to estimate the rate of O2 consumption in working muscle. During exercise when the work rate changes quickly, however, non-invasive in vivo measurements to estimate muscle O2 consumption are not sufficient to characterize cellular respiration of working muscle. To interpret transient changes of venous O2 concentration, blood flow, and O2 consumption in working muscle, a mathematical model of O2 transport and consumption based on dynamic mass balances is required. In this study, a comparison is made of the differences between simulations of O2 uptake and O2 consumption within working skeletal muscle based on a dynamic model and quasi-steady-state approximations. The conditions are specified under which the quasi-steady-state approximation becomes invalid. PMID:18290343

  19. Knee extensor muscle oxygen consumption in relation to muscle activation.

    PubMed

    Kooistra, R D; Blaauboer, M E; Born, J R; de Ruiter, C J; de Haan, A

    2006-12-01

    Recently, fatigability and muscle oxygen consumption (mVO(2)) during sustained isometric contractions were found to be less at shorter (30 degrees knee angle; 0 degrees = full extension) compared to longer knee extensor muscle lengths (90 degrees ) and, at low torques, less in the rectus femoris (RF) muscle than in the vastus lateralis and medialis. In the present study we hypothesized that these findings could be accounted for by a knee angle- and a muscle-dependent activation respectively. On two experimental days rectified surface EMG (rsEMG) was obtained as a measure of muscle activation in nine healthy young males. In addition, on day 1 maximal torque capacity (MTC) was carefully determined using superimposed nerve stimulation on brief high intensity contractions (> 70%MVC) at 30, 60 and 90 degrees knee angles. On day 2, subjects performed longer lasting isometric contractions (10-70%MTC) while mVO(2) was measured using near-infrared spectroscopy (NIRS). At 30 degrees , maximal mVO(2) was reached significantly later (11.0 s +/- 6.5 s) and was 57.9 +/- 8.3% less (average +/- SD, across intensities and muscles) than mVO(2) at 60 and 90 degrees (p < 0.05). However, rsEMG was on average only 18.0 +/- 11.8% (p = 0.062) less at the start of the contraction at 30 degrees . At 10%MTC at all knee angles, maximal mVO(2) of the RF occurred significantly later (28.8 +/- 36.0 s) and showed a significantly smaller increase in rsEMG compared to both vasti. In conclusion, it is unlikely that the tendency for less intense muscle activation could fully account for the approximately 60% lower oxygen consumption at 30 degrees , but the later increase in RFmVO(2) seemed to be caused by a less strong activation of the RF.

  20. Effects of TFM and Bayer 73 on in vivo oxygen consumption of the aquatic midge Chironomus tentans

    USGS Publications Warehouse

    Kawatski, J.A.; Dawson, V.K.; Reuvers, J.L.

    1974-01-01

    Exposure of fourth instar larvae of Chironomus tentans to 2.0-8.0 mg/liter of TFM (3-trifluormethyl-4-nitrophenol) for 6 hr at 22 A? 0.5 C in soft water resulted in a significantly increased rate of larval oxygen consumption compared to that of control larvae, as measured with the Warburg respirometer. Maximum stimulation of oxygen consumption occurred with 8.0 mg/liter of TFM, and 1.0 mg/liter of TFM had no measurable effect on basal respiration. When hardness of exposure water was progressively increased, the effect of TFM on oxygen consumption was diminished. Bayer 73 (5,2'-dichloro-4'-nitrosalicylanilide) stimulated oxygen consumption at 0.75 and 1.0 mg/liter, had no significant effect at concentrations less that 0.75 mg/liter, and inhibited oxygen consumption at concentrations of 1.20 mg/liter or greater. Mixtures of TFM and Bayer 73, in the ratio of 98:2, had no greater effect on oxygen consumption than TFM alone.

  1. Sediment oxygen consumption and vertical flux of organic matter in the Seto Inland Sea, Japan

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.

    2003-02-01

    Vertical flux of organic matter and rates of sediment oxygen consumption (SOC) were measured in summer 2000 at a muddy sediment site (21 m depth) in the Seto Inland Sea, Japan. During the 26-day experimental period (15 July to 9 August), a diatom bloom occurred, lasting for about a week. The vertical flux of organic carbon and chlorophyll a ( FC and Fchl), measured at 12.5 m depth, showed a sharp peak following the development of the bloom. Under these conditions, SOC ranged from 1.4 to 3.0 mmol O 2 m -2 h -1, and it was strongly influenced by the biomass of macrozoobenthos present in the experimental chambers used for SOC measurements. However, macrozoobenthic oxygen consumption made up only 5% of SOC. SOC variations were not coupled with corresponding changes in FC or Fchl. The effects of other factors, such as water temperature, as well as levels of sediment chlorophyll a and bacterial abundance, were minor, presumably because these parameters did not vary strongly during the study period. The average SOC value corrected for macrozoobenthos oxygen consumption (1.8 mmol O 2 m -2 h -1) and converted into the decomposition rate of organic material was nearly balanced with the FC averaged over the experimental period (0.7 C m -2 day -1). This indicates that this muddy sediment area in the Seto Inland Sea plays an important role in the degradation of organic material supplied from the water column.

  2. Analysis and interpretation of microplate-based oxygen consumption and pH data.

    PubMed

    Divakaruni, Ajit S; Paradyse, Alexander; Ferrick, David A; Murphy, Anne N; Jastroch, Martin

    2014-01-01

    Breakthrough technologies to measure cellular oxygen consumption and proton efflux are reigniting the study of cellular energetics by increasing the scope and pace with which discoveries are made. As we learn the variation in metabolism between cell types is large, it is helpful to continually provide additional perspectives and update our roadmap for data interpretation. In that spirit, this chapter provides the following for those conducting microplate-based oxygen consumption experiments: (i) a description of the standard parameters for measuring respiration in intact cells, (ii) a framework for data analysis and normalization, and (iii) examples of measuring respiration in permeabilized cells to follow up results observed with intact cells. Additionally, rate-based measurements of extracellular pH are increasingly used as a qualitative indicator of glycolytic flux. As a resource to help interpret these measurements, this chapter also provides a detailed accounting of proton production during glucose oxidation in the context of plate-based assays. PMID:25416364

  3. Analysis and interpretation of microplate-based oxygen consumption and pH data.

    PubMed

    Divakaruni, Ajit S; Paradyse, Alexander; Ferrick, David A; Murphy, Anne N; Jastroch, Martin

    2014-01-01

    Breakthrough technologies to measure cellular oxygen consumption and proton efflux are reigniting the study of cellular energetics by increasing the scope and pace with which discoveries are made. As we learn the variation in metabolism between cell types is large, it is helpful to continually provide additional perspectives and update our roadmap for data interpretation. In that spirit, this chapter provides the following for those conducting microplate-based oxygen consumption experiments: (i) a description of the standard parameters for measuring respiration in intact cells, (ii) a framework for data analysis and normalization, and (iii) examples of measuring respiration in permeabilized cells to follow up results observed with intact cells. Additionally, rate-based measurements of extracellular pH are increasingly used as a qualitative indicator of glycolytic flux. As a resource to help interpret these measurements, this chapter also provides a detailed accounting of proton production during glucose oxidation in the context of plate-based assays.

  4. Seasonal Oxygen Dynamics in a Thermokarst Bog in Interior Alaska: Implications for Rates of Methane Oxidation

    NASA Astrophysics Data System (ADS)

    Neumann, R. B.; Moorberg, C.; Wong, A.; Waldrop, M. P.; Turetsky, M. R.

    2015-12-01

    Methane is a potent greenhouse gas, and wetlands represent the largest natural source of methane to the atmosphere. However, much of the methane generated in anoxic wetlands never gets emitted to the atmosphere; up to >90% of generated methane can get oxidized to carbon dioxide. Thus, oxidation is an important methane sink and changes in the rate of methane oxidation can affect wetland methane emissions. Most methane is aerobically oxidized at oxic-anoxic interfaces where rates of oxidation strongly depend on methane and oxygen concentrations. In wetlands, oxygen is often the limiting substrate. To improve understanding of belowground oxygen dynamics and its impact on methane oxidation, we deployed two planar optical oxygen sensors in a thermokarst bog in interior Alaska. Previous work at this site indicated that, similar to other sites, rates of methane oxidation decrease over the growing season. We used the sensors to track spatial and temporal patterns of oxygen concentrations over the growing season. We coupled these in-situ oxygen measurements with periodic oxygen injection experiments performed against the sensor to quantify belowground rates of oxygen consumption. We found that over the season, the thickness of the oxygenated water layer at the peatland surface decreased. Previous research has indicated that in sphagnum-dominated peatlands, like the one studied here, rates of methane oxidation are highest at or slightly below the water table. It is in these saturated but oxygenated locations that both methane and oxygen are available. Thus, a seasonal reduction in the thickness of the oxygenated water layer could restrict methane oxidation. The decrease in thickness of the oxygenated layer coincided with an increase in the rate of oxygen consumption during our oxygen injection experiments. The increase in oxygen consumption was not explained by temperature; we infer it was due to an increase in substrate availability for oxygen consuming reactions and

  5. Oxygen consumption and evaporative water loss in infants with congenital heart disease.

    PubMed Central

    Kennaird, D L

    1976-01-01

    The relation between environmental temperature, heat production, oxygen consumption, and evaporative water loss was studied in 67 infants with congenital heart disease. The majority of the cyanosed infants had a low minimum oxygen consumption, a low evaporative water loss, and a diminished metabolic response to cold stress. Minimum oxygen consumption and evaporative water loss rose in 6 of these infants after the construction of a surgical shunt. Many of the ill acyanotic infants had an abnormally high minimum oxygen consumption, and those in cardiac failure often continued to sweat in an environment below the thermoneutral temperature zone. PMID:942228

  6. Effects of fluctuating hypoxia on benthic oxygen consumption in the Black Sea (Crimean shelf)

    NASA Astrophysics Data System (ADS)

    Lichtschlag, A.; Donis, D.; Janssen, F.; Jessen, G. L.; Holtappels, M.; Wenzhöfer, F.; Mazlumyan, S.; Sergeeva, N.; Waldmann, C.; Boetius, A.

    2015-08-01

    The outer western Crimean shelf of the Black Sea is a natural laboratory to investigate effects of stable oxic versus varying hypoxic conditions on seafloor biogeochemical processes and benthic community structure. Bottom-water oxygen concentrations ranged from normoxic (175 μmol O2 L-1) and hypoxic (< 63 μmol O2 L-1) or even anoxic/sulfidic conditions within a few kilometers' distance. Variations in oxygen concentrations between 160 and 10 μmol L-1 even occurred within hours close to the chemocline at 134 m water depth. Total oxygen uptake, including diffusive as well as fauna-mediated oxygen consumption, decreased from 15 mmol m-2 d-1 on average in the oxic zone, to 7 mmol m-2 d-1 on average in the hypoxic zone, correlating with changes in macrobenthos composition. Benthic diffusive oxygen uptake rates, comprising respiration of microorganisms and small meiofauna, were similar in oxic and hypoxic zones (on average 4.5 mmol m-2 d-1), but declined to 1.3 mmol m-2 d-1 in bottom waters with oxygen concentrations below 20 μmol L-1. Measurements and modeling of porewater profiles indicated that reoxidation of reduced compounds played only a minor role in diffusive oxygen uptake under the different oxygen conditions, leaving the major fraction to aerobic degradation of organic carbon. Remineralization efficiency decreased from nearly 100 % in the oxic zone, to 50 % in the oxic-hypoxic zone, to 10 % in the hypoxic-anoxic zone. Overall, the faunal remineralization rate was more important, but also more influenced by fluctuating oxygen concentrations, than microbial and geochemical oxidation processes.

  7. Photoacoustic and Doppler ultrasound for oxygen consumption estimation: implementation on a clinical array system

    NASA Astrophysics Data System (ADS)

    Jiang, Yan; Harrison, Tyler; Zemp, Roger J.

    2011-03-01

    Recently, we have developed a combined photoacoustic and high-frequency Doppler ultrasound system with a single element transducer to estimate the metabolic rate of oxygen consumption in small animal models. However, the long scanning time due to mechanical motion may be a limitation of our swept-scan system. In this work, the single element transducer was replaced by a clinical array transducer which may provide more accurate flow velocity estimations, higher frame rates, improved penetration depth, and improved depth-of-field due to dynamic focusing capabilities. We used an array system from Verasonics Inc. which enables flexible pulse-sequence programming and parallel channel data acquisition, along with a pulsed laser and optical parametric oscillator. For flow estimation, we implemented a flash- Doppler sequence which transmits ensembles of plane-wave excitations. Echo signals are beamformed and subjected to wall-filtering and Kasai flow estimation algorithms. High frame rates over a wide region can be achieved. Combined interlaced photoacoustic and Doppler imaging on flow phantoms has been performed on this system. We demonstrate the ability to image animal blood to depths of 1.5-cm with high signal-to-noise with both modalities. The light penetration is 2-cm. We discuss the performance of Doppler flow estimation and photoacoustic oxygen saturation estimation and their role in future work of estimating oxygen consumption.

  8. Normal Muscle Oxygen Consumption and Fatigability in Sickle Cell Patients Despite Reduced Microvascular Oxygenation and Hemorheological Abnormalities

    PubMed Central

    Waltz, Xavier; Pichon, Aurélien; Lemonne, Nathalie; Mougenel, Danièle; Lalanne-Mistrih, Marie-Laure; Lamarre, Yann; Tarer, Vanessa; Tressières, Benoit; Etienne-Julan, Maryse; Hardy-Dessources, Marie-Dominique; Hue, Olivier; Connes, Philippe

    2012-01-01

    Background/Aim Although it has been hypothesized that muscle metabolism and fatigability could be impaired in sickle cell patients, no study has addressed this issue. Methods We compared muscle metabolism and function (muscle microvascular oxygenation, microvascular blood flow, muscle oxygen consumption and muscle microvascular oxygenation variability, which reflects vasomotion activity, maximal muscle force and local muscle fatigability) and the hemorheological profile at rest between 16 healthy subjects (AA), 20 sickle cell-hemoglobin C disease (SC) patients and 16 sickle cell anemia (SS) patients. Results Muscle microvascular oxygenation was reduced in SS patients compared to the SC and AA groups and this reduction was not related to hemorhelogical abnormalities. No difference was observed between the three groups for oxygen consumption and vasomotion activity. Muscle microvascular blood flow was higher in SS patients compared to the AA group, and tended to be higher compared to the SC group. Multivariate analysis revealed that muscle oxygen consumption was independently associated with muscle microvascular blood flow in the two sickle cell groups (SC and SS). Finally, despite reduced muscle force in sickle cell patients, their local muscle fatigability was similar to that of the healthy subjects. Conclusions Sickle cell patients have normal resting muscle oxygen consumption and fatigability despite hemorheological alterations and, for SS patients only, reduced muscle microvascular oxygenation and increased microvascular blood flow. Two alternative mechanisms can be proposed for SS patients: 1) the increased muscle microvascular blood flow is a way to compensate for the lower muscle microvascular oxygenation to maintain muscle oxygen consumption to normal values or 2) the reduced microvascular oxygenation coupled with a normal resting muscle oxygen consumption could indicate that there is slight hypoxia within the muscle which is not sufficient to limit

  9. Rodent Working Heart Model for the Study of Myocardial Performance and Oxygen Consumption.

    PubMed

    DeWitt, Elizabeth S; Black, Katherine J; Kheir, John N

    2016-01-01

    Isolated working heart models have been used to understand the effects of loading conditions, heart rate and medications on myocardial performance in ways that cannot be accomplished in vivo. For example, inotropic medications commonly also affect preload and afterload, precluding load-independent assessments of their myocardial effects in vivo. Additionally, this model allows for sampling of coronary sinus effluent without contamination from systemic venous return, permitting assessment of myocardial oxygen consumption. Further, the advent of miniaturized pressure-volume catheters has allowed for the precise quantification of markers of both systolic and diastolic performance. We describe a model in which the left ventricle can be studied while performing both volume and pressure work under controlled conditions. In this technique, the heart and lungs of a Sprague-Dawley rat (weight 300-500 g) are removed en bloc under general anesthesia. The aorta is dissected free and cannulated for retrograde perfusion with oxygenated Krebs buffer. The pulmonary arteries and veins are ligated and the lungs removed from the preparation. The left atrium is then incised and cannulated using a separate venous cannula, attached to a preload block. Once this is determined to be leak-free, the left heart is loaded and retrograde perfusion stopped, creating the working heart model. The pulmonary artery is incised and cannulated for collection of coronary effluent and determination of myocardial oxygen consumption. A pressure-volume catheter is placed into the left ventricle either retrograde or through apical puncture. If desired, atrial pacing wires can be placed for more precise control of heart rate. This model allows for precise control of preload (using a left atrial pressure block), afterload (using an afterload block), heart rate (using pacing wires) and oxygen tension (using oxygen mixtures within the perfusate). PMID:27584550

  10. Effects of fluctuating hypoxia on benthic oxygen consumption in the Black Sea (Crimean Shelf)

    NASA Astrophysics Data System (ADS)

    Lichtschlag, A.; Donis, D.; Janssen, F.; Jessen, G. L.; Holtappels, M.; Wenzhöfer, F.; Mazulmyan, S.; Sergeeva, N.; Waldmann, C.; Boetius, A.

    2015-04-01

    The outer Western Crimean Shelf of the Black Sea is a natural laboratory to investigate effects of stable oxic vs. varying hypoxic conditions on seafloor biogeochemical processes and benthic community structure. Bottom water oxygen concentrations varied between normoxic (175 μmol O2 L-1) and hypoxic (< 63 μmol O2 L-1) or even anoxic/sulfidic conditions within a few kilometres distance. Variations in oxygen concentrations between 160 and 10 μmol L-1 even occurred within hours close to the chemocline at 134 m water depth. Total oxygen uptake, including diffusive as well as fauna-mediated oxygen consumption, decreased from > 15 mmol m-2 d-1 in the oxic zone to < 9 mmol m-2 d-1 in the hypoxic zone, correlating with changes in macrobenthos composition. Benthic diffusive oxygen uptake rates, comprising microbial respiration plus reoxidation of inorganic products, were around 4.5 mmol m-2 d-1, but declined to 1.3 mmol m-2 d-1 at oxygen concentrations below 20 μmol L-1. Measurements and modelling of pore water profiles indicated that reoxidation of reduced compounds played only a minor role in the diffusive oxygen uptake, leaving the major fraction to aerobic degradation of organic carbon. Remineralization efficiency decreased from 100% in the oxic zone, to 50% in the oxic-hypoxic, to 10% in the hypoxic-anoxic zone. Overall the faunal remineralization rate was more important, but also more influenced by fluctuating oxygen concentrations than microbial and geochemical oxidation processes.

  11. Influence of solid corrosion by-products on the consumption of dissolved oxygen in copper pipes

    SciTech Connect

    Vargas, Ignacio T.; Alsina, Marco A.; Pastén, Pablo A.; Pizarro, Gonzalo E.

    2009-06-12

    Research on corrosion of copper pipes has given little consideration to the influence of solid corrosion by-products on the processes occurring at the metal-liquid interface. Consequently, the effect of such solid phases on the rate of dissolved oxygen (DO) consumption remains poorly understood. In-situ experiments were performed in copper pipes under different carbonate concentrations and ageing times. Our results show that the amount of solid corrosion by-products and concentration of hydrogen ions affect the rate of DO consumption during stagnation. Furthermore, our findings support the existing hypothesis that the available concentration of hydrogen ions, rather than DO, is the limiting factor for copper release into drinking water.

  12. Nitric oxide inhibits succinate dehydrogenase-driven oxygen consumption in potato tuber mitochondria in an oxygen tension-independent manner.

    PubMed

    Simonin, Vagner; Galina, Antonio

    2013-01-01

    NO (nitric oxide) is described as an inhibitor of plant and mammalian respiratory chains owing to its high affinity for COX (cytochrome c oxidase), which hinders the reduction of oxygen to water. In the present study we show that in plant mitochondria NO may interfere with other respiratory complexes as well. We analysed oxygen consumption supported by complex I and/or complex II and/or external NADH dehydrogenase in Percoll-isolated potato tuber (Solanum tuberosum) mitochondria. When mitochondrial respiration was stimulated by succinate, adding the NO donors SNAP (S-nitroso-N-acetyl-DL-penicillamine) or DETA-NONOate caused a 70% reduction in oxygen consumption rate in state 3 (stimulated with 1 mM of ADP). This inhibition was followed by a significant increase in the Km value of SDH (succinate dehydrogenase) for succinate (Km of 0.77±0.19 to 34.3±5.9 mM, in the presence of NO). When mitochondrial respiration was stimulated by external NADH dehydrogenase or complex I, NO had no effect on respiration. NO itself and DETA-NONOate had similar effects to SNAP. No significant inhibition of respiration was observed in the absence of ADP. More importantly, SNAP inhibited PTM (potato tuber mitochondria) respiration independently of oxygen tensions, indicating a different kinetic mechanism from that observed in mammalian mitochondria. We also observed, in an FAD reduction assay, that SNAP blocked the intrinsic SDH electron flow in much the same way as TTFA (thenoyltrifluoroacetone), a non-competitive SDH inhibitor. We suggest that NO inhibits SDH in its ubiquinone site or its Fe-S centres. These data indicate that SDH has an alternative site of NO action in plant mitochondria. PMID:23039043

  13. CORRECTING ENERGY EXPENDITURES FOR FATIGUE AND EXCESS POST-EXERCISE OXYGEN CONSUMPTION

    EPA Science Inventory

    The EPA's human exposure and dose models often require a quantification of oxygen consumption for a simulated individual. Oxygen consumption is dependent on the individual's current level of physical activity (PA), which is determined from activity diaries selected from the Conso...

  14. Eucalanoid copepod metabolic rates in the oxygen minimum zone of the eastern tropical north Pacific: Effects of oxygen and temperature

    NASA Astrophysics Data System (ADS)

    Cass, Christine J.; Daly, Kendra L.

    2014-12-01

    The eastern tropical north Pacific Ocean (ETNP) contains one of the world's most severe oxygen minimum zones (OMZs), where oxygen concentrations are less than 2 μmol kg-1. OMZs cause habitat compression, whereby species intolerant of low oxygen are restricted to near-surface oxygenated waters. Copepods belonging to the family Eucalanidae are dominant zooplankters in this region and inhabit a variety of vertical habitats within the OMZ. The purpose of this study was to compare the metabolic responses of three species of eucalanoid copepods, Eucalanus inermis, Rhincalanus rostrifrons, and Subeucalanus subtenuis, to changes in temperature and environmental oxygen concentrations. Oxygen consumption and urea, ammonium, and phosphate excretion rates were measured via end-point experiments at three temperatures (10, 17, and 23 °C) and two oxygen concentrations (100% and 15% air saturation). S. subtenuis, which occurred primarily in the upper 50 m of the water column at our study site, inhabiting well-oxygenated to upper oxycline conditions, had the highest metabolic rates per unit weight, while E. inermis, which was found throughout the water column to about 600 m depth in low oxygen waters, typically had the lowest metabolic rates. Rates for R. rostrifrons (found primarily between 200 and 300 m depth) were intermediate between the other two species and more variable. Metabolic ratios suggested that R. rostrifrons relied more heavily on lipids to fuel metabolism than the other two species. S. subtenuis was the only species that demonstrated a decrease in oxygen consumption rates (at intermediate 17 °C temperature treatment) when environmental oxygen concentrations were lowered. The percentage of total measured nitrogen excreted as urea (% urea-N), as well as overall urea excretion rates, responded in a complex manner to changes in temperature and oxygen concentration. R. rostrifrons and E. inermis excreted a significantly higher % of urea-N in low oxygen treatments at

  15. Effects of salinity and body mass on oxygen consumption and ammonia excretion of mudskipper Boleophthalmus pectinirostris

    NASA Astrophysics Data System (ADS)

    Cao, Fujun; Wang, Hui

    2015-01-01

    We evaluated the effects of salinity and body mass on the oxygen consumption rate and ammonia excretion rate of mudskipper Boleophthalmus pectinirostris under laboratory conditions. Salinity and body mass had highly significant effects on the oxygen consumption rate ( R O) and ammonia excretion rate ( R N) ( P<0.01). The interactive effects between salinity and body mass on R O and R N were insignificant ( P>0.05) and highly significant ( P<0.01), respectively. R O and R N of B. pectinirostris decreased significantly as the individual body mass increased. The relationship between R O and body mass was represented by R O = aW b ( R 2=0.956, P<0.01). The relationship between R N and the body mass of B. pectinirostris was represented by R N = cW d ( R 2=0.966, P<0.01). The R O/ R N (O:N) ratios increased significantly as the salinity increased from 12 to 27, but decreased as salinity increased from 27 to 32. The atomic O:N ratios were significantly higher at 27 than at other salinity levels. The average O:N ratio was 25.25. Lipid and carbohydrate were the primary energy sources and protein was the secondary energy source within the salinity range 12-32. R O and R N were significantly higher at 27 than at other salinity levels. Our results suggest that the optimum salinity level for B. pectinirostris is 27.

  16. Effects of salinity and body mass on oxygen consumption and ammonia excretion of mudskipper Boleophthalmus pectinirostris

    NASA Astrophysics Data System (ADS)

    Cao, Fujun; Wang, Hui

    2014-09-01

    We evaluated the effects of salinity and body mass on the oxygen consumption rate and ammonia excretion rate of mudskipper Boleophthalmus pectinirostris under laboratory conditions. Salinity and body mass had highly significant effects on the oxygen consumption rate (R O) and ammonia excretion rate (R N) (P<0.01). The interactive effects between salinity and body mass on R O and R N were insignificant (P>0.05) and highly significant (P<0.01), respectively. R O and R N of B. pectinirostris decreased significantly as the individual body mass increased. The relationship between R O and body mass was represented by R O=aW b (R 2=0.956, P<0.01). The relationship between R N and the body mass of B. pectinirostris was represented by R N=cW d (R 2=0.966, P<0.01). The R O/R N (O:N) ratios increased significantly as the salinity increased from 12 to 27, but decreased as salinity increased from 27 to 32. The atomic O:N ratios were significantly higher at 27 than at other salinity levels. The average O:N ratio was 25.25. Lipid and carbohydrate were the primary energy sources and protein was the secondary energy source within the salinity range 12-32. R O and R N were significantly higher at 27 than at other salinity levels. Our results suggest that the optimum salinity level for B. pectinirostris is 27.

  17. Phylogenetic analysis of mammalian maximal oxygen consumption during exercise.

    PubMed

    Dlugosz, Elizabeth M; Chappell, Mark A; Meek, Thomas H; Szafranska, Paulina A; Zub, Karol; Konarzewski, Marek; Jones, James H; Bicudo, J Eduardo P W; Nespolo, Roberto F; Careau, Vincent; Garland, Theodore

    2013-12-15

    We compiled published values of mammalian maximum oxygen consumption during exercise ( ) and supplemented these data with new measurements of for the largest rodent (capybara), 20 species of smaller-bodied rodents, two species of weasels and one small marsupial. Many of the new data were obtained with running-wheel respirometers instead of the treadmill systems used in most previous measurements of mammalian . We used both conventional and phylogenetically informed allometric regression models to analyze of 77 'species' (including subspecies or separate populations within species) in relation to body size, phylogeny, diet and measurement method. Both body mass and allometrically mass-corrected showed highly significant phylogenetic signals (i.e. related species tended to resemble each other). The Akaike information criterion corrected for sample size was used to compare 27 candidate models predicting (all of which included body mass). In addition to mass, the two best-fitting models (cumulative Akaike weight=0.93) included dummy variables coding for three species previously shown to have high (pronghorn, horse and a bat), and incorporated a transformation of the phylogenetic branch lengths under an Ornstein-Uhlenbeck model of residual variation (thus indicating phylogenetic signal in the residuals). We found no statistical difference between wheel- and treadmill-elicited values, and diet had no predictive ability for . Averaged across all models, the allometric scaling exponent was 0.839, with 95% confidence limits of 0.795 and 0.883, which does not provide support for a scaling exponent of 0.67, 0.75 or unity. PMID:24031059

  18. Maximal Oxygen Consumption Is Reduced in Aquaporin-1 Knockout Mice.

    PubMed

    Al-Samir, Samer; Goossens, Dominique; Cartron, Jean-Pierre; Nielsen, Søren; Scherbarth, Frank; Steinlechner, Stephan; Gros, Gerolf; Endeward, Volker

    2016-01-01

    We have measured maximal oxygen consumption ([Formula: see text]O2,max) of mice lacking one or two of the established mouse red-cell CO2 channels AQP1, AQP9, and Rhag. We intended to study whether these proteins, by acting as channels for O2, determine O2 exchange in the lung and in the periphery. We found that [Formula: see text]O2,max as determined by the Helox technique is reduced by ~16%, when AQP1 is knocked out, but not when AQP9 or Rhag are lacking. This figure holds for animals respiring normoxic as well as hypoxic gas mixtures. To see whether the reduction of [Formula: see text]O2,max is due to impaired O2 uptake in the lung, we measured carotid arterial O2 saturation (SO2) by pulse oximetry. Neither under normoxic (inspiratory O2 21%) nor under hypoxic conditions (11% O2) is there a difference in SO2 between AQP1null and WT mice, suggesting that AQP1 is not critical for O2 uptake in the lung. The fact that the % reduction of [Formula: see text]O2,max is identical in normoxia and hypoxia indicates moreover that the limitation of [Formula: see text]O2,max is not due to an O2 diffusion problem, neither in the lung nor in the periphery. Instead, it appears likely that AQP1null animals exhibit a reduced [Formula: see text]O2,max due to the reduced wall thickness and muscle mass of the left ventricles of their hearts, as reported previously. We conclude that very likely the properties of the hearts of AQP1 knockout mice cause a reduced maximal cardiac output and thus cause a reduced [Formula: see text]O2,max, which constitutes a new phenotype of these mice. PMID:27559317

  19. Maximal Oxygen Consumption Is Reduced in Aquaporin-1 Knockout Mice

    PubMed Central

    Al-Samir, Samer; Goossens, Dominique; Cartron, Jean-Pierre; Nielsen, Søren; Scherbarth, Frank; Steinlechner, Stephan; Gros, Gerolf; Endeward, Volker

    2016-01-01

    We have measured maximal oxygen consumption (V˙O2,max) of mice lacking one or two of the established mouse red-cell CO2 channels AQP1, AQP9, and Rhag. We intended to study whether these proteins, by acting as channels for O2, determine O2 exchange in the lung and in the periphery. We found that V˙O2,max as determined by the Helox technique is reduced by ~16%, when AQP1 is knocked out, but not when AQP9 or Rhag are lacking. This figure holds for animals respiring normoxic as well as hypoxic gas mixtures. To see whether the reduction of V˙O2,max is due to impaired O2 uptake in the lung, we measured carotid arterial O2 saturation (SO2) by pulse oximetry. Neither under normoxic (inspiratory O2 21%) nor under hypoxic conditions (11% O2) is there a difference in SO2 between AQP1null and WT mice, suggesting that AQP1 is not critical for O2 uptake in the lung. The fact that the % reduction of V˙O2,max is identical in normoxia and hypoxia indicates moreover that the limitation of V˙O2,max is not due to an O2 diffusion problem, neither in the lung nor in the periphery. Instead, it appears likely that AQP1null animals exhibit a reduced V˙O2,max due to the reduced wall thickness and muscle mass of the left ventricles of their hearts, as reported previously. We conclude that very likely the properties of the hearts of AQP1 knockout mice cause a reduced maximal cardiac output and thus cause a reduced V˙O2,max, which constitutes a new phenotype of these mice. PMID:27559317

  20. Influence of hyperbaric oxygen on left ventricular contractility, total coronary blood flow, and myocardial oxygen consumption in the conscious dog.

    PubMed

    Savitt, M A; Rankin, J S; Elberry, J R; Owen, C H; Camporesi, E M

    1994-06-01

    It is known that hyperbaric oxygenation (HBO) decreases total coronary blood flow (TCBF) and cardiac output (CO). To determine whether this is related to an alteration in myocardial contractility, 10 chronically instrumented conscious dogs were studied during pharmacologic autonomic blockade. Left ventricular (LV) volume was measured with ultrasonic transducers, LV transmural pressure with micromanometers, TCBF with Doppler-flow probes, and coronary AVO2 difference (A-CSO2) was calculated from direct LV and coronary sinus (CS) sampling. To evaluate the effect of increased oxygenation, data were obtained during resting control conditions and during dynamic vena caval occlusions (VCO), at 1 atmosphere of pressure, while breathing air (1 bar/0.21); at 3 atmospheres, breathing compressed air (3 bar/0.21), and at 3 atmospheres breathing 100% oxygen (3 bar/1.0). Because of autonomic blockade, heart rate (HR) was not statistically different in the three conditions. With increasing oxygenation, arterial oxygen tension (PaO2) increased from 85 +/- 5 mmHg (mean +/- SD) at 1 bar/0.21, to 1374 +/- 201 mmHg at 3 bar/1.0 whereas arterial carbon dioxide tension (PaCO2) and pH values were not statistically different. Arterial oxygen content (AO2 content) and CSO2 content increased significantly (both P < 0.05) with increasing PaO2. LV stroke volume (SV), CO, coronary blood flow, and myocardial oxygen consumption (MVO2) were all significantly reduced (P < 0.05) with increasing levels of oxygenation. Intrinsic myocardial function, as measured by the stroke-work/end-diastolic volume relationship was unchanged from 1 bar/0.21 to 3 bar/0.21, and to 3 bar/1.0 (P < 0.20). Thus, the diminished TCBF, CO, and MVO2 associated with HBO do not seem to be associated with a primary alteration in myocardial contractility, but rather may result from a physiologic autoregulation of the myocardium to increasing levels of PaO2. PMID:8061558

  1. Impact of zinc and nickel on oxygen consumption of benthic microbial communities assessed with microsensors.

    PubMed

    Viret, H; Pringault, O; Duran, R

    2006-08-15

    In this study, the effect of zinc and nickel on oxygen consumption in sediments was determined using oxygen microsensors. Sediments from the southwest lagoon of New Caledonia, in the vicinity of the city of Nouméa, were incubated nearby in situ conditions and exposed to Zn and Ni concentrations of 20 and 60 mg l(-1). The depth distribution of oxygen consumption was estimated from the steady-state oxygen microprofiles, and the effects of metal were compared on the distributions before and after spiking. In most cases, metal had a strong effect on oxygen consumption at the surface. After 6 h exposure, oxygen consumption was only 10-40% of the initial value. However, the strong decrease in oxygen consumption observed at the sediment surface was counterbalanced by an increase of oxygen consumption deeper in the sediment. This is probably due to (i) a downward migration of aerobic microbial microorganisms living at the surface in order to escape the toxic effect of metal or/and (ii) a switch of the facultative aerobes from the low efficiency fermentation mode to the high-energy aerobic respiration mode.

  2. Effect of flosequinan (BTS 49465) on myocardial oxygen consumption.

    PubMed

    Greenberg, S; Touhey, B; Paul, J

    1990-06-01

    BTS 49465 (flosequinan), a putative selective, balanced arterial and venous vasodilator, displays positive inotropic effects in doses lower than those producing vasodilation. Thus rather than unloading the myocardium, flosequinan may increase myocardial work and oxygen consumption (MVO2), and may adversely affect the patient with myocardial ischemia or compromised coronary blood flow. This study compared the effects of flosequinan with milrinone, a mixed positive inotropic agent and vasodilator, and with nitroprusside (SNP), a standard direct-acting vasodilator, on myocardial dP/dT, MVO2, and myocardial energetics in the normal pentobartital-anesthetized dog. The effect of flosequinan on myocardial work was also evaluated in the dog with propranolol-induced heart failure (PIHF). Fifteen minutes after intraduodenal (id) administration of flosequinan (0.3, 1.0, and 3.0 mg/kg) to seven dogs, mean myocardial dP/dT was increased by 11%, 27%, and 54%, respectively, whereas stroke MVO2 was increased by 10%, 24%, and 47%, respectively. Doses of flosequinan greater than 0.3 mg/kg decreased left ventricular (LV) work but LV efficiency decreased in a dose-related manner. Milrinone (0.1, 0.3, and 1.0 mg/kg, id) increased LV dp/dt by 34%, 68%, and 104% above basal values, while increasing stroke MVO2 by 24%, 106%, and 249%, respectively (n = 7). LV work and LV efficiency decreased after each dose of milrinone. SNP (0.001, 0.003, and 0.01 mg/kg/min, intravenously) did not increase dP/dT but decreased LV work by 28%, 42%, and 46% (n = 5). In animals with PIHF, flosequinan (1 and 3 mg/kg, id) increased LV dP/dT 58% and 87% and increased LV work by 58% and 76% above control values. It was concluded that (1) flosequinan is a positive inotropic agent as well as a vasodilator; (2) in the normal animal the energy cost of positive inotropic activity is less with flosequinan than with milrinone, despite the lesser vasodilating action of the former; and (3) in the animal with a depressed

  3. Effect of salinity on oxygen consumption in fishes: a review.

    PubMed

    Ern, R; Huong, D T T; Cong, N V; Bayley, M; Wang, T

    2014-04-01

    The effect of salinity on resting oxygen uptake was measured in the perch Perca fluviatilis and available information on oxygen uptake in teleost species at a variety of salinities was reviewed. Trans-epithelial ion transport against a concentration gradient requires energy and exposure to salinities osmotically different from the body fluids therefore imposes an energetic demand that is expected to be lowest in brackish water compared to fresh and sea water. Across species, there is no clear trend between oxygen uptake and salinity, and estimates of cost of osmotic and ionic regulation vary from a few per cent to >30% of standard metabolism. PMID:24665828

  4. Non-respiratory oxygen consumption pathways in anaerobically-grown Saccharomyces cerevisiae: evidence and partial characterization.

    PubMed

    Rosenfeld, Eric; Beauvoit, Bertrand; Rigoulet, Michel; Salmon, Jean-Michel

    2002-11-01

    Despite the absence of an alternative mitochondrial ubiquinol oxidase, Saccharomyces cerevisiae consumes oxygen in an antimycin A- and cyanide-resistant manner. Cyanide-resistant respiration is typically used when the classical respiratory chain is impaired or absent (i.e in anaerobically-grown cells shifted to normoxia or in respiratory-deficient cells). We characterized the non-respiratory oxygen consumption pathways operating during anoxic-normoxic transitions in glucose-repressed resting cells. High-resolution oxygraphy confirmed that the cellular non-respiratory oxygen consumption pathway is sensitive to high concentrations of cyanide, azide, SHAM and TTFA, and revealed several new characteristics. First, the use of sterol biosynthesis inhibitors showed that this pathway makes a considerable contribution (about 25%) to both endogenous and glucose-dependent oxygen consumption. Anaerobically-grown glucose-repressed cells exhibited high apparent oxygen affinities (K(m) for oxygen = 0.5-1 micro M), even in mutants deficient in respiration or sterol synthesis. Exogeneously added glucose and endogenous stored carbohydrates were the only substrates that were efficient for cellular oxygen consumption (apparent K(m) for exogenous glucose = 2-3 mM). On the other hand, fluorimetric measurements of the cellular NAD(P)H pool showed that the cellular oxygen consumption (sterol biosynthesis and unknown pathways) was dependent more on the intracellular level of NADPH than of NADH. High oxygen affinity NADPH-dependent oxygen consumption systems were thought to be mainly localized in microsomal membranes, and several data indicated a significant contribution made by uncoupled p450 systems, together with still uncharacterized systems. Such activities are associated in vitro with a massive production of O(2) (.-) and, to a lower extent, H(2)O(2) and a likely concomitant production of H(2)O.

  5. Changes in oxygen consumption induced by t-butyl hydroperoxide in perfused rat liver. Effect of free-radical scavengers.

    PubMed Central

    Videla, L A; Villena, M I; Donoso, G; Giulivi, C; Boveris, A

    1984-01-01

    The addition of t-butyl hydroperoxide to perfused rat liver elicited a biphasic effect on hepatic respiration. A rapid fall in liver oxygen consumption was initially observed, followed by a recovery phase leading to respiratory rates higher than the initial steady-state values of oxygen uptake. This overshoot in hepatic oxygen uptake was abolished by free-radical scavengers such as (+)-cyanidanol-3 or butylated hydroxyanisole at concentrations that did not alter mitochondrial respiration. (+)-Cyanidanol-3 was also able to facilitate the recovery of respiration, the diminution in the calculated rate of hydroperoxide utilization and the decrease in liver GSH content produced by two consecutive pulses of t-butyl hydroperoxide. It is suggested that the t-butyl hydroperoxide-induced overshoot in liver respiration is related to increased utilization of oxygen for lipid peroxidation as a consequence of free radicals produced in the scission of the hydroperoxide by cellular haemoproteins. PMID:6508746

  6. An experimental set-up to analyse the oxygen consumption of elastomers during ageing by using a differential oxygen analyser

    NASA Astrophysics Data System (ADS)

    Herzig, Alexander; Johlitz, Michael; Lion, Alexander

    2015-11-01

    Ageing of polymers becomes more and more important. This can be seen by the increasing number of research projects dealing with this topic. However, the influence of oxygen on changes in the mechanical performance is undisputable and important with respect to the lifetime of polymer products. Therefore, a respirometer offers the potential to detect the smallest amounts of oxygen changes in the polymers' ambient air. It will be used to analyse the oxygen consumption of rubber which is exposed for different times to elevated temperatures. In this contribution, virgin rubber samples are aged for various times in a sealed chamber at temperatures of 60, 80 and 100°C. The decline of the oxygen concentration in the ambient air is measured by flushing the chamber with dried and cleaned air which is conducted into the respirometer. The oxygen concentration is compared with that in a reference chamber, which is exposed to the same ageing conditions as the sample under investigation. The absorbed oxygen is relevant for ageing and a considerable factor for further investigations. For this reason, an experimental set-up using a differential oxygen analyser is developed, which allows for ageing several samples simultaneously in external climate chambers. The comparison of the change in the mechanical material behaviour after ageing can provide an important contribution for improving constitutive models or ongoing researches on the fatigue strength of polymers. This work shows the development of an improved method for combining mechanical testing and the measurement of oxygen consumption.

  7. Microscale measurements of oxygen diffusion and consumption in subaqueous sulfide tailings

    NASA Astrophysics Data System (ADS)

    Elberling, Bo; Damgaard, Lars Riis

    2001-06-01

    The disposal of sulfide mine tailings in an environmentally sound, yet cost-effective, manner is an issue facing most metal mines. Subaqueous tailing disposal is considered an attractive option for disposal that limits oxygen (O 2) availability within sulfide mine tailings and controlling sulfide oxidation and the resultant acid mine drainage (AMD). Assuming that O 2 profiles represent steady-state conditions, we aim to evaluate the depth-dependent and temperature-dependent rates of O 2 consumption in saturated mine tailings. Measurements include microscale O 2 gradients and diffusivity profiles within columns representing undisturbed mine tailing profiles from an impoundment near Nanisivik Mine in northern Canada. Measurements were made across the diffusive boundary layer (DBL) above the tailing-water interface as well as in the tailings below. Laboratory measurements of O 2 profiles are compared to in situ profiles. From the laboratory results it is possible to evaluate the O 2 flux across the DBL and the depth-integrated O 2 uptake. The results are compared with the average sulfate production rate over 3 months. O 2 uptake in saturated tailings is discussed in relation to O 2 uptake measured in columns after free drainage. The methods applied provide consistent O 2 consumption rates as well as reliable predictions for controlling AMD by keeping tailings under water.

  8. Effect of oxygen reduction rate and constant low dissolved oxygen concentrations on two estuarine fish

    SciTech Connect

    Burton, D.T.; Richardson, L.B.; Moore, C.J.

    1980-09-01

    The relationship between mean lethal oxygen concentration and rate of reduction of dissolved oxygen that induces fish kills was determined for Atlantic menhaden (Brevoortia tyrannus). Reduction of dissolved oxygen at hourly rates of 1.00 to 0.08 mg/liter had no effect on the mean lethal oxygen concentrations. There was an inverse relationship between the median time to death (LT50) and rate of oxygen reduction that can be used to estimate how quickly a fish kill may occur when oxygen concentrations decrease at a constant rate. Atlantic menhaden were less resistant than spot (Leiostomus xanthurus) when both species were exposed to constant low concentrations of oxygen. The lethal threshold concentrations for Atlantic menhaden and spot at 28/sup 0/C were approximately 1.1 and 0.7 mg/liter, respectively, whereas, the 96-hour, 5% lethal concentrations were approximately 1.6 and 0.8 mg/liter, respectively.

  9. Functional Capacity, Respiratory Muscle Strength, and Oxygen Consumption Predict Mortality in Patients with Cirrhosis

    PubMed Central

    Telles da Rosa, Luis Henrique; Garcia, Eduardo; Marroni, Cláudio Augusto

    2016-01-01

    Introduction. Liver diseases influence musculoskeletal functions and may negatively affect the exercise capacity of patients with cirrhosis. Aim. To test the relationship between the six-minute walk test (6MWT), maximal inspiratory pressure (MIP), and exercise capacity (VO2peak) measures and the survival rate of patients with cirrhosis. Methods. This prospective cohort study consisted of 86 patients diagnosed with cirrhosis with the following aetiology: hepatitis C virus (HCV), hepatitis B virus (HBV), and/or alcoholic cirrhosis (AC). All patients were followed up for three years and submitted to the 6MWT, pressure measurements with a compound gauge, and an exercise test (VO2peak). Results. The survival analysis showed that the individuals who covered a distance shorter than 410 m during the 6MWT had a survival rate of 55% compared with a rate of 97% for the individuals who walked more than 410 m (p = 0.0001). Individuals with MIPs below −70 cmH2O had a survival rate of 62% compared with a rate of 93% for those with MIPs above −70 cmH2O (p = 0.0001). The patients with values below 17 mL/kg had a survival rate of 55% compared with a rate of 94% for those with values above 17 mL/kg (p = 0.0001). Conclusion. The 6MWT distance, MIP, and oxygen consumption are predictors of mortality in patients with cirrhosis. PMID:27559536

  10. Functional Capacity, Respiratory Muscle Strength, and Oxygen Consumption Predict Mortality in Patients with Cirrhosis.

    PubMed

    Faustini Pereira, José Leonardo; Galant, Lucas Homercher; Rossi, Danusa; Telles da Rosa, Luis Henrique; Garcia, Eduardo; de Mello Brandão, Ajácio Bandeira; Marroni, Cláudio Augusto

    2016-01-01

    Introduction. Liver diseases influence musculoskeletal functions and may negatively affect the exercise capacity of patients with cirrhosis. Aim. To test the relationship between the six-minute walk test (6MWT), maximal inspiratory pressure (MIP), and exercise capacity (VO2peak) measures and the survival rate of patients with cirrhosis. Methods. This prospective cohort study consisted of 86 patients diagnosed with cirrhosis with the following aetiology: hepatitis C virus (HCV), hepatitis B virus (HBV), and/or alcoholic cirrhosis (AC). All patients were followed up for three years and submitted to the 6MWT, pressure measurements with a compound gauge, and an exercise test (VO2peak). Results. The survival analysis showed that the individuals who covered a distance shorter than 410 m during the 6MWT had a survival rate of 55% compared with a rate of 97% for the individuals who walked more than 410 m (p = 0.0001). Individuals with MIPs below -70 cmH2O had a survival rate of 62% compared with a rate of 93% for those with MIPs above -70 cmH2O (p = 0.0001). The patients with values below 17 mL/kg had a survival rate of 55% compared with a rate of 94% for those with values above 17 mL/kg (p = 0.0001). Conclusion. The 6MWT distance, MIP, and oxygen consumption are predictors of mortality in patients with cirrhosis. PMID:27559536

  11. Integrating spatial and temporal oxygen data to improve the quantification of in situ petroleum biodegradation rates.

    PubMed

    Davis, Gregory B; Laslett, Dean; Patterson, Bradley M; Johnston, Colin D

    2013-03-15

    Accurate estimation of biodegradation rates during remediation of petroleum impacted soil and groundwater is critical to avoid excessive costs and to ensure remedial effectiveness. Oxygen depth profiles or oxygen consumption over time are often used separately to estimate the magnitude and timeframe for biodegradation of petroleum hydrocarbons in soil and subsurface environments. Each method has limitations. Here we integrate spatial and temporal oxygen concentration data from a field experiment to develop better estimates and more reliably quantify biodegradation rates. During a nine-month bioremediation trial, 84 sets of respiration rate data (where aeration was halted and oxygen consumption was measured over time) were collected from in situ oxygen sensors at multiple locations and depths across a diesel non-aqueous phase liquid (NAPL) contaminated subsurface. Additionally, detailed vertical soil moisture (air-filled porosity) and NAPL content profiles were determined. The spatial and temporal oxygen concentration (respiration) data were modeled assuming one-dimensional diffusion of oxygen through the soil profile which was open to the atmosphere. Point and vertically averaged biodegradation rates were determined, and compared to modeled data from a previous field trial. Point estimates of biodegradation rates assuming no diffusion ranged up to 58 mg kg(-1) day(-1) while rates accounting for diffusion ranged up to 87 mg kg(-1) day(-1). Typically, accounting for diffusion increased point biodegradation rate estimates by 15-75% and vertically averaged rates by 60-80% depending on the averaging method adopted. Importantly, ignoring diffusion led to overestimation of biodegradation rates where the location of measurement was outside the zone of NAPL contamination. Over or underestimation of biodegradation rate estimates leads to cost implications for successful remediation of petroleum impacted sites.

  12. Luciferase-dependent oxygen consumption by bioluminescent vibrios

    SciTech Connect

    Makemson, J.C.

    1986-02-01

    Oxygen uptake due to luciferase in two luminous Vibrio species was estimated in vivo by utilizing inhibitors having specificities for luciferase (decanol) and cytochromes (cyanide). Cyanide titration of respiration revealed a component of oxygen uptake less sensitive to cyanide which was completely inhibitable by low concentrations of decanol. From this it was estimated that in vivo luciferase is responsible for less than 12% (Vibrio harveyi) or 20% (Vibrio fischeri) of the total respiration. From these data in vivo bioluminescent quantum yields are estimated to be not lower than 1.7 and 2.6%, respectively.

  13. Somatosensory evoked changes in cerebral oxygen consumption measured non-invasively in premature neonates

    PubMed Central

    Roche-Labarbe, Nadege; Fenoglio, Angela; Radakrishnan, Harsha; Kocienski-Filip, Marcia; Carp, Stefan A.; Dubb, Jay; Boas, David A.; Grant, P. Ellen; Franceschini, Maria Angela

    2013-01-01

    The hemodynamic functional response is used as a reliable marker of neuronal activity in countless studies of brain function and cognition. In newborns and infants, however, conflicting results have appeared in the literature concerning the typical response, and there is little information on brain metabolism and functional activation. Measurement of all hemodynamic components and oxygen metabolism is critical for understanding neurovascular coupling in the developing brain. To this end, we combined multiple near infrared spectroscopy techniques to measure oxy- and deoxy-hemoglobin concentrations, cerebral blood volume (CBV), and relative cerebral blood flow (CBF) in the somatosensory cortex of 6 preterm neonates during passive tactile stimulation of the hand. By combining these measures we estimated relative changes in the cerebral metabolic rate of oxygen consumption (rCMRO2). CBF starts increasing immediately after stimulus onset, and returns to baseline before blood volume. This is consistent with the model of pre-capillary arteriole active dilation driving the CBF response, with a subsequent CBV increase influenced by capillaries and veins dilating passively to accommodate the extra blood. rCMRO2 estimated using the steady-state formulation shows a biphasic pattern: an increase immediately after stimulus onset, followed by a post-stimulus undershoot due to blood flow returning faster to baseline than oxygenation. However, assuming a longer mean transit time from the arterial to the venous compartment, due to the immature vascular system of premature infants, reduces the post-stimulus undershoot and increases the flow/consumption ratio to values closer to adult values reported in the literature. We are the first to report changes in local rCBF and rCMRO2 during functional activation in preterm infants. The ability to measure these variables in addition to hemoglobin concentration changes is critical for understanding neurovascular coupling in the developing

  14. Temperature induced variation in oxygen consumption of juvenile and adult stage of the dog conch Laevistrombus canarium (Linnaeus 1758)

    NASA Astrophysics Data System (ADS)

    Hassan, Wan Nurul Husna Wan; Amin, S. M. Nurul; Ghaffar, Mazlan Abd; Cob, Zaidi Che

    2015-09-01

    Laevistrombus canarium Linnaeus, 1758 is one of the important edible sea snail within the western Johor Straits, Malaysia. In this study, the impact of temperature on oxygen consumption (MO2) of L. canarium based on their ontogenetic changes (juvenile and adult) was measured in the laboratory condition at 22.0, 26.0, 30.0 and 34.0°C. Measurement of MO2 were taken every 1 s for 60 min on 4.20 - 34.00 g dog conch using respirometry chamber. All experiments were carried out in static conditions in five replicates with one snail per chambers. The results of oxygen consumption showed that juvenile dog conch respired at the rate of 0.163 ml h-1 and adult respired at the rate of 0.119 ml h-1. Consequently, the oxygen consumption in juvenile and adult dog conch was expressed as a total energy spends. The results indicates that total energy spend for oxygen consumed (ml h-1) of L. canarium at different temperature regimes (22.0 to 34.0°C) slightly increased over time period (0.63 ± 0.12 to 3.24 ± 0.05 J h-1) respectively. This finding of the present study suggested L. canarium is well adapted for life in high temperature environment.

  15. Oxygen consumption constrains food intake in fish fed diets varying in essential amino acid composition.

    PubMed

    Saravanan, Subramanian; Geurden, Inge; Figueiredo-Silva, A Cláudia; Nusantoro, Suluh; Kaushik, Sadasivam; Verreth, Johan; Schrama, Johan W

    2013-01-01

    Compromisation of food intake when confronted with diets deficient in essential amino acids is a common response of fish and other animals, but the underlying physiological factors are poorly understood. We hypothesize that oxygen consumption of fish is a possible physiological factor constraining food intake. To verify, we assessed the food intake and oxygen consumption of rainbow trout fed to satiation with diets which differed in essential amino acid (methionine and lysine) compositions: a balanced vs. an imbalanced amino acid diet. Both diets were tested at two water oxygen levels: hypoxia vs. normoxia. Trout consumed 29% less food under hypoxia compared to normoxia (p<0.001). Under both hypoxia and normoxia trout significantly reduced food intake by 11% and 16% respectively when fed the imbalanced compared to the balanced amino acid diet. Oxygen consumption of the trout per unit body mass remained identical for both diet groups not only under hypoxia but also under normoxia (p>0.05). This difference in food intake between diets under normoxia together with the identical oxygen consumption supports the hypothesis that food intake in fish can be constrained by a set-point value of oxygen consumption, as seen here on a six-week time scale.

  16. Effect of Training Status on Oxygen Consumption in Women After Resistance Exercise.

    PubMed

    Benton, Melissa J; Waggener, Green T; Swan, Pamela D

    2016-03-01

    This study compared acute postexercise oxygen consumption in 11 trained women (age, 46.5 ± 1.6 years; body mass index [BMI], 28.4 ± 1.7 kg·m(-2) and 11 untrained women (age, 46.5 ± 1.5 years; BMI, 27.5 ± 1.5 kg·m(-2)) after resistance exercise (RE). Resistance exercise consisted of 3 sets of 8 exercises (8-12 repetitions at 50-80% 1 repetition maximum). Oxygen consumption (VO2 ml·min(-1)) was measured before and after (0, 20, 40, 60, 90, and 120 minutes) RE. Immediately after cessation of RE (time 0), oxygen consumption increased in both trained and untrained women and remained significantly above baseline through 60 minutes after exercise (p < 0.01). Total oxygen consumption during recovery was 31.3 L in trained women and 27.4 L in untrained women (p = 0.07). In trained women, total oxygen consumption was strongly related to absolute (kg) lean mass (r = 0.88; p < 0.001), relative (kilogram per square meter) lean mass (r = 0.91; p < 0.001), and duration of exercise (r = 0.68; p ≤ 0.05), but in untrained women, only training volume-load was related to total oxygen consumption (r = 0.67; p ≤ 0.05). In trained women, 86% of the variance in oxygen consumption was explained by lean mass and exercise duration, whereas volume-load explained 45% in untrained women. Our findings suggest that, in women, resistance training increases metabolic activity of lean tissue. Postexercise energy costs of RE are determined by the duration of stimulation provided by RE rather than absolute work (volume-load) performed. This phenomenon may be related to type II muscle fibers and increased protein synthesis.

  17. Measurement of oxygen consumption during muscle flaccidity exercise by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Fukuda, K.; Fukawa, Y.

    2013-03-01

    Quantitative measurement oxygen consumption in the muscles is important to evaluate the effect of the exercise. Near-infrared spectroscopy (NIRS) is a noninvasive method for measuring muscle oxygenation. However, measurement results are affected by blood volume change due to changes in the blood pressure. In order to evaluate changes in blood volume and to improve measurement accuracy, we proposed a calculation method of three-wavelength measurement with considering the scattering factor and the measurement with monitoring blood flow for measuring the temporal change of the oxygen concentration more precisely. We applied three-wavelength light source (680nm, 808nm and 830nm) for the continued wave measurement. Two detectors (targeted detector and the reference detector) were placed near the target muscle and apart from it. We measured the blood flow by controlling the intravascular pressure and the oxygen consumption with the handgrip exercise in the forearm. The measured results show that the scattering factor contains the artifact at the surface and the blood flow in the artery and the vein in the same phase. The artifact and the blood flow in the same phase are reduced from the oxygenated and the deoxygenated hemoglobin densities. Thus our proposed method is effective for reducing the influence of the artifact and the blood flow in the same phase from the oxygen consumption measurement. Further, it is shown that the oxygen consumption is measured more accurately by subtracting the blood flow measured by the reference detector.

  18. Oxygen consumption during hover-feeding in free-ranging Anna hummingbirds.

    PubMed

    Bartholomew, G A; Lighton, J R

    1986-07-01

    Rates of oxygen consumption during hover-feeding of wild, unrestrained, adult male Anna hummingbirds (Calypte anna) were measured with an artificial outdoor feeder converted into a respirometer mask. A computer sampled changes in O2 concentration in air drawn through the mask, automatically detecting the presence of a hummingbird from a drop in the O2 concentration, and photoelectrically timing the duration over which the feeder functioned as a mask. Birds coming to the feeder were weighed on a trapeze perch suspended from a force transducer. Feeding bouts consisted of sallies which carried the head in and out of the feeding mask about once a second. The volume of O2 consumed per feeding sally was linearly related to the length of the sally. The energy cost of hover-feeding in five hummingbirds, mean mass 4.6 g, was 41.5 +/- 6.3 ml O2 g-1 h-1.

  19. Peak oxygen consumption and lactate threshold in full mask versus mouth mask conditions during incremental exercise.

    PubMed

    Dooly, C R; Johnson, A T; Dotson, C O; Vaccaro, P; Soong, P

    1996-01-01

    Respirator masks vary in inhalation and exhalation resistance, and in dead volume. It is believed that these factors may contribute significantly to an early anaerobic threshold in mask wearers during maximal exercise. Very little is known concerning the effect of respirator masks on maximal oxygen consumption (VO2max) and the lactate threshold (LT). The purpose of the present study was to assess peak VO2 (VO2peak), LT and the ventilatory threshold (VT) of 14 experienced cyclists performing two maximal cycle exercise protocols while wearing a full respirator mask (FM) (M17 type) and a mouth mask (MM). VO2peak was 10% lower under FM conditions. Peak values for ventilation (VEpeak), respiratory rate (fbpeak) and tidal volume (VTpeak) were all significantly lower under with FM versus MM conditions. Performance time and maximal heart rate (fcpeak) were not different between mask conditions. The LT and VT when expressed in %VO2peak, and the lactate concentration (mmol.l-1) at LT and VT were not significantly different across mask conditions. Bland-Altman plots demonstrated longer inhalation times, decreased Fr values and greater oxygen extraction under FM conditions. Thus, perhaps due to the increased inhalation resistance of the FM condition, subjects were unable to attain their "normal" VO2 despite similar performance times and maximal fc. Furthermore, despite a diminished VO2peak with FM, LT and VT appeared to be the same as with a MM.

  20. Validating the relationship between 3-dimensional body acceleration and oxygen consumption in trained Steller sea lions.

    PubMed

    Volpov, Beth L; Rosen, David A S; Trites, Andrew W; Arnould, John P Y

    2015-08-01

    We tested the ability of overall dynamic body acceleration (ODBA) to predict the rate of oxygen consumption ([Formula: see text]) in freely diving Steller sea lions (Eumetopias jubatus) while resting at the surface and diving. The trained sea lions executed three dive types-single dives, bouts of multiple long dives with 4-6 dives per bout, or bouts of multiple short dives with 10-12 dives per bout-to depths of 40 m, resulting in a range of activity and oxygen consumption levels. Average metabolic rate (AMR) over the dive cycle or dive bout calculated was calculated from [Formula: see text]. We found that ODBA could statistically predict AMR when data from all dive types were combined, but that dive type was a significant model factor. However, there were no significant linear relationships between AMR and ODBA when data for each dive type were analyzed separately. The potential relationships between AMR and ODBA were not improved by including dive duration, food consumed, proportion of dive cycle spent submerged, or number of dives per bout. It is not clear whether the lack of predictive power within dive type was due to low statistical power, or whether it reflected a true absence of a relationship between ODBA and AMR. The average percent error for predicting AMR from ODBA was 7-11 %, and standard error of the estimated AMR was 5-32 %. Overall, the extensive range of dive behaviors and physiological conditions we tested indicated that ODBA was not suitable for estimating AMR in the field due to considerable error and the inconclusive effects of dive type.

  1. Left ventricular oxygen consumption and organ blood flow distribution during pulsatile ventricular assist.

    PubMed

    Pantalos, G M; Marks, J D; Riebman, J B; Everett, S D; Burns, G L; Burton, N A; DePaulis, R

    1988-01-01

    One goal of left ventricular assistance is the reduction of left ventricular myocardial oxygen consumption while delivering adequate organ blood flow. The effect of assist device operation control mode and uptake cannulation method on the achievement of this goal was studied in six acutely prepared calves with healthy hearts. All combinations of left ventricular assistance significantly reduced the myocardial oxygen consumption; the reduction was independent of control mode. During ventricular assistance, regional organ blood flow distribution and myocardial endocardial/epicardial blood flow ratio were not different from values during the control, unassisted condition. Regardless of the left ventricular assist device uptake method or operational control mode, significant reduction in myocardial oxygen consumption was achieved while maintaining organ blood flow distribution.

  2. Oxygen consumption by oak chips in a model wine solution; Influence of the botanical origin, toast level and ellagitannin content.

    PubMed

    Navarro, María; Kontoudakis, Nikolaos; Giordanengo, Thomas; Gómez-Alonso, Sergio; García-Romero, Esteban; Fort, Francesca; Canals, Joan Miquel; Hermosín-Gutíerrez, Isidro; Zamora, Fernando

    2016-05-15

    The botanical origin, toast level and ellagitannin content of oak chips in a model wine solution have been studied in terms of their influence on oxygen consumption. French oak chips released significantly higher amounts of ellagitannins than American oak chips at any toast level. The release of ellagitannins by oak chips decreased as the toast level increased in the French oak but this trend was not so clear in American oak. Oxygen consumption rate was clearly related to the level of released ellagitannins. Therefore, oak chips should be chosen for their potential to release ellagitannins release should be considered, not only because they can have a direct impact on the flavor and body of the wine, but also because they can protect against oxidation.

  3. Kinetics of oxygen consumption after a flash of light in the lateral ocellus of the barnacle.

    PubMed

    Poitry, S; Widmer, H

    1988-10-01

    Until recently, polarographic methods for measuring the time course of transient changes in the rate of oxygen consumption (DeltaQO(2)) have been applied only to tissue preparations containing thousands of cells. Here, we describe DeltaQO(2) measurements on the lateral ocellus of the barnacle (Balanus eburneus) which contains only three photoreceptor cells. The decrement of partial pressure of oxygen (DeltaPO(2)) elicited by an 80 ms flash of light was measured near the cells with a microelectrode and the DeltaQO(2) was calculated from the DeltaPO(2) using a model of diffusion with spherical symmetry. As shown by mathematical simulation, the exact shape of the preparation is not crucial for our measurements of the time course of the DeltaQO(2). For a given DeltaQO(2), the model describes correctly the attenuation of the DeltaPO(2) measured at increased distances from the preparation. To know more about the mechanisms controlling the DeltaQO(2), we compared it with the electrical response of the photoreceptor cells: both responses have a similar spectral dependence, but only the DeltaQO(2) was abolished by a 10-min exposure to 50 muM dinitrophenol or to 3 mM amytal. We conclude that the DeltaQO(2) reflects an increase in mitochondrial respiration and that it is initiated by the phototransformation of rhodopsin, as was already found in the honeybee drone retina (Dimitracos and Tsacopoulos, 1985; Jones and Tsacopoulos, 1987).

  4. CELL RESPIRATION STUDIES : II. A COMPARATIVE STUDY OF THE OXYGEN CONSUMPTION OF BLOOD FROM NORMAL INDIVIDUALS AND PATIENTS WITH INCREASED LEUCOCYTE COUNTS (SEPSIS; CHRONIC MYELOGENOUS LEUCEMIA).

    PubMed

    Daland, G A; Isaacs, R

    1927-06-30

    1. The oxygen consumption of blood of normal individuals, when the hemoglobin is saturated with oxygen, is practically zero within the limits of experimental error of the microspirometer used. 2. The oxygen consumed in a microspirometer by the blood of patients with chronic myelogenous leucemia with a high white blood cell count, and of one with leucocytosis from sepsis, was proportional to the number of adult polymorphonuclear neutrophils in the blood. 3. No correlation could be made between the rate of oxygen absorption and the total number of white blood cells in the blood, or the total number of immature cells, or the number of red blood cells, or the amount of oxyhemoglobin. 4. The blood of patients with chronic myelogenous leucemia continued to use oxygen in the microspirometer longer than that of normal individuals, and the hemoglobin, in the leucemic bloods, became desaturated even though exposed to air. 5. In blood in which the bulk. of the cells were immature and the mature cells few, the oxygen consumption was lower than in blood in which the mature cells predominated. The rate of oxygen consumption of the immature cells was relatively low as compared to the mature. 6. The slower rate of oxygen absorption by the immature leucocytes in chronic myelogenous leucemia as compared to the mature cells, places them, in accord with Warburg's reports, in the class of the malignant tissues in this respect rather than in the group of young or embryonic cells.

  5. Role of oxygen consumption in hypoxia protection by translation factor depletion.

    PubMed

    Scott, Barbara; Sun, Chun-Ling; Mao, Xianrong; Yu, Cong; Vohra, Bhupinder P S; Milbrandt, Jeffrey; Crowder, C Michael

    2013-06-15

    The reduction of protein synthesis has been associated with resistance to hypoxic cell death. Which components of the translation machinery control hypoxic sensitivity and the precise mechanism has not been systematically investigated, although a reduction in oxygen consumption has been widely assumed to be the mechanism. Using genetic reagents in Caenorhabditis elegans, we examined the effect on organismal survival after hypoxia of knockdown of 10 factors functioning at the three principal steps in translation. Reduction-of-function of all 10 translation factors significantly increased hypoxic survival to varying degrees, not fully accounted for by the level of translational suppression. Measurement of oxygen consumption showed that strong hypoxia resistance was possible without a significant decrease in oxygen consumption. Hypoxic sensitivity had no correlation with lifespan or reactive oxygen species sensitivity, two phenotypes associated with reduced translation. Resistance to tunicamycin, which produces misfolded protein toxicity, was the only phenotype that significantly correlated with hypoxic sensitivity. Translation factor knockdown was also hypoxia protective for mouse primary neurons. These data show that translation factor knockdown is hypoxia protective in both C. elegans and mouse neurons and that oxygen consumption does not necessarily determine survival; rather, mitigation of misfolded protein toxicity is more strongly associated with hypoxic protection. PMID:23531825

  6. Role of oxygen consumption in hypoxia protection by translation factor depletion

    PubMed Central

    Scott, Barbara; Sun, Chun-Ling; Mao, Xianrong; Yu, Cong; Vohra, Bhupinder P. S.; Milbrandt, Jeffrey; Crowder, C. Michael

    2013-01-01

    SUMMARY The reduction of protein synthesis has been associated with resistance to hypoxic cell death. Which components of the translation machinery control hypoxic sensitivity and the precise mechanism has not been systematically investigated, although a reduction in oxygen consumption has been widely assumed to be the mechanism. Using genetic reagents in Caenorhabditis elegans, we examined the effect on organismal survival after hypoxia of knockdown of 10 factors functioning at the three principal steps in translation. Reduction-of-function of all 10 translation factors significantly increased hypoxic survival to varying degrees, not fully accounted for by the level of translational suppression. Measurement of oxygen consumption showed that strong hypoxia resistance was possible without a significant decrease in oxygen consumption. Hypoxic sensitivity had no correlation with lifespan or reactive oxygen species sensitivity, two phenotypes associated with reduced translation. Resistance to tunicamycin, which produces misfolded protein toxicity, was the only phenotype that significantly correlated with hypoxic sensitivity. Translation factor knockdown was also hypoxia protective for mouse primary neurons. These data show that translation factor knockdown is hypoxia protective in both C. elegans and mouse neurons and that oxygen consumption does not necessarily determine survival; rather, mitigation of misfolded protein toxicity is more strongly associated with hypoxic protection. PMID:23531825

  7. The oxygen transfer rate as key parameter for the characterization of Hansenula polymorpha screening cultures.

    PubMed

    Stöckmann, Christoph; Maier, Ulrike; Anderlei, Tibor; Knocke, Christof; Gellissen, Gerd; Büchs, Jochen

    2003-10-01

    Screening cultures are usually non-monitored and non-controlled due to a lack of appropriate measuring techniques. A new device for online measurement of oxygen transfer rate (OTR) in shaking-flask cultures was used for monitoring the screening of Hansenula polymorpha. A shaking frequency of 300 rpm and a filling volume of 20 ml in 250-ml flasks ensured a sufficient oxygen transfer capacity of 0.032 mol (l h)(-1) and thus a respiration not limited by oxygen. Medium buffered with 0.01 mol phosphate l(-1) (pH 6.0) resulted in pH-inhibited respiration, whereas buffering with 0.12 mol phosphate l(-1) (pH 4.1) resulted in respiration that was not inhibited by pH. The ammonium demand was balanced by establishing fixed relations between oxygen, ammonium, and glycerol consumption with 0.245+/-0.015 mol ammonium per mol glycerol. Plate precultures with complex glucose medium reduced the specific growth rate coefficient to 0.18 h(-1) in subsequent cultures with minimal glycerol medium. The specific growth rate coefficient increased to 0.26 h(-1) when exponentially growing precultures with minimal glycerol medium were used for inoculation. Changes in biomass, glycerol, ammonium, and pH over time were simulated on the basis of oxygen consumption.

  8. Long-term fasting decreases mitochondrial avian UCP-mediated oxygen consumption in hypometabolic king penguins

    PubMed Central

    Rey, Benjamin; Halsey, Lewis G.; Dolmazon, Virginie; Rouanet, Jean-Louis; Roussel, Damien; Handrich, Yves; Butler, Patrick J.; Duchamp, Claude

    2008-01-01

    In endotherms, regulation of the degree of mitochondrial coupling affects cell metabolic efficiency. Thus it may be a key contributor to minimizing metabolic rate during long periods of fasting. The aim of the present study was to investigate whether variation in mitochondrial avian uncoupling proteins (avUCP), as putative regulators of mitochondrial oxidative phosphorylation, may contribute to the ability of king penguins (Aptenodytes patagonicus) to withstand fasting for several weeks. After 20 days of fasting, king penguins showed a reduced rate of whole animal oxygen consumption (V̇o2; −33%) at rest, together with a reduced abundance of avUCP and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1-α) mRNA in pectoralis muscle (−54%, −36%, respectively). These parameters were restored after the birds had been refed for 3 days. Furthermore, in recently fed, but not in fasted penguins, isolated muscle mitochondria showed a guanosine diphosphate-inhibited, fatty acid plus superoxide-activated respiration, indicating the presence of a functional UCP. It was calculated that variation in mitochondrial UCP-dependent respiration in vitro may contribute to nearly 20% of the difference in resting V̇o2 between fed or refed penguins and fasted penguins measured in vivo. These results suggest that the lowering of avUCP activity during periods of long-term energetic restriction may contribute to the reduction in metabolic rate and hence the ability of king penguins to face prolonged periods of fasting. PMID:18495832

  9. Long-term fasting decreases mitochondrial avian UCP-mediated oxygen consumption in hypometabolic king penguins.

    PubMed

    Rey, Benjamin; Halsey, Lewis G; Dolmazon, Virginie; Rouanet, Jean-Louis; Roussel, Damien; Handrich, Yves; Butler, Patrick J; Duchamp, Claude

    2008-07-01

    In endotherms, regulation of the degree of mitochondrial coupling affects cell metabolic efficiency. Thus it may be a key contributor to minimizing metabolic rate during long periods of fasting. The aim of the present study was to investigate whether variation in mitochondrial avian uncoupling proteins (avUCP), as putative regulators of mitochondrial oxidative phosphorylation, may contribute to the ability of king penguins (Aptenodytes patagonicus) to withstand fasting for several weeks. After 20 days of fasting, king penguins showed a reduced rate of whole animal oxygen consumption (Vo2; -33%) at rest, together with a reduced abundance of avUCP and peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC1-alpha) mRNA in pectoralis muscle (-54%, -36%, respectively). These parameters were restored after the birds had been refed for 3 days. Furthermore, in recently fed, but not in fasted penguins, isolated muscle mitochondria showed a guanosine diphosphate-inhibited, fatty acid plus superoxide-activated respiration, indicating the presence of a functional UCP. It was calculated that variation in mitochondrial UCP-dependent respiration in vitro may contribute to nearly 20% of the difference in resting Vo2 between fed or refed penguins and fasted penguins measured in vivo. These results suggest that the lowering of avUCP activity during periods of long-term energetic restriction may contribute to the reduction in metabolic rate and hence the ability of king penguins to face prolonged periods of fasting. PMID:18495832

  10. Linking rates of diffusion and consumption in relation to resources.

    PubMed

    Avgar, Tal; Kuefler, Daniel; Fryxell, John M

    2011-08-01

    The functional response is a fundamental model of the relationship between consumer intake rate and resource abundance. The random walk is a fundamental model of animal movement and is well approximated by simple diffusion. Both models are central to our understanding of numerous ecological processes but are rarely linked in ecological theory. To derive a synthetic model, we draw on the common logical premise underlying these models and show how the diffusion and consumption rates of consumers depend on elementary attributes of naturally occurring consumer-resource interactions: the abundance, spatial aggregation, and traveling speed of resources as well as consumer handling time and directional persistence. We show that resource aggregation may lead to increased consumer diffusion and, in the case of mobile resources, reduced consumption rate. Resource-dependent movement patterns have traditionally been attributed to area-restricted search, reflecting adaptive decision making by the consumer. Our synthesis provides a simple alternative hypothesis that such patterns could also arise as a by-product of statistical movement mechanics.

  11. Music increases alcohol consumption rate in young females.

    PubMed

    Stafford, Lorenzo D; Dodd, Hannah

    2013-10-01

    Previous field research has shown that individuals consumed more alcohol and at a faster rate in environments paired with loud music. Theoretically, this effect has been linked to approach/avoidance accounts of how music influences arousal and mood, but no work has tested this experimentally. In the present study, female participants (n = 45) consumed an alcoholic (4% alcohol-by-volume) beverage in one of three contexts: slow tempo music, fast tempo music, or a no-music control. Results revealed that, compared with the control, the beverage was consumed fastest in the two music conditions. Interestingly, whereas arousal and negative mood declined in the control condition, this was not the case for either of the music conditions, suggesting a downregulation of alcohol effects. We additionally found evidence for music to disrupt sensory systems in that, counterintuitively, faster consumption was driven by increases in perceived alcohol strength, which, in turn, predicted lower breath alcohol level (BrAL). These findings suggest a unique interaction of music environment and psychoactive effects of alcohol itself on consumption rate. Because alcohol consumed at a faster rate induces greater intoxication, these findings have implications for applied and theoretical work.

  12. Bioreactor scale-up and oxygen transfer rate in microbial processes: an overview.

    PubMed

    Garcia-Ochoa, Felix; Gomez, Emilio

    2009-01-01

    bioreactors. The present work is aimed at the reviewing of the oxygen transfer rate (OTR) in bioprocesses to provide a better knowledge about the selection, design, scale-up and development of bioreactors. First, the most used measuring methods are revised; then the main empirical equations, including those using dimensionless numbers, are considered. The possible increasing on OTR due to the oxygen consumption by the cells is taken into account through the use of the biological enhancement factor. Theoretical predictions of both the volumetric mass transfer coefficient and the enhancement factor that have been recently proposed are described; finally, different criteria for bioreactor scale-up are considered in the light of the influence of OTR and OUR affecting the dissolved oxygen concentration in real bioprocess.

  13. A novel approach to the assess biotic oxygen consumption in marine sediment communities

    NASA Astrophysics Data System (ADS)

    Baranov, Victor; Queiros, Ana; Widdicombe, Stephen; Stephens, Nick; Lessin, Gennadi; Krause, Stefan; Lewandowski, Joerg

    2016-04-01

    Bioturbation , the mixing of the sediment matrix by burrowing animals impacts sediment metabolism, including respiration through redistribution of particulate organics, changes in bacterial biota diversity and acitivity, as well as via burrowing fauna's own metabolism. Bioturbation, reflecting faunal activity, is also a proxy for the general sedimentary ecosystem health, and can be impacted by many of emerging marine environmental issues such as ocean acidification, warming and the occurrence of heat waves. Sedimentary oxygen consumption is often taken as a proxy for the activity of bioturbating fauna, but determining baselines can be difficult because of the confounding effects of other fauna and microbes present in sediments, as well as irnorganic processes that consume oxygen. Limitations therefore exist in current methodologies, and numerous confounding factors are hampering progress in this area. Here, we present novel method for the assessment of sediment respiration which is expected to be affected only by the biogenic oxygen consumption (namely aerobic respiration). As long as tracer reduction "immune" to inorganic oxygen consumption, so that measurements using this method can be used, alongside traditional methods, to decouple biological respiration from inorganic oxygen consumption reactions. The tracer is easily detectable, non-toxic and can be applied in systems with constant oxygen supply. The latter allow for incubation without the need to to work with unsealed experimental units, bringing procedural advantage over traditional methods. Consequently assessed bioturbating fauna is not exposed to hypoxia and additional stress. Here, we had applied system for the first time to investigate impacts of a common North-Atlantic bioturbator, the brittle star Amphiura filiformis, - on respiration of marine sediments. Two series of experiments were conducted with animals and sediment collected from Cawsand Bay, Plymouth, UK Preliminary results show that tracer

  14. Metabolic oxygen consumption measurement with a single-cell biosensor after particle microbeam irradiation.

    PubMed

    Xu, Yanping; Zhang, Bo; Messerli, Mark; Randers-Pehrson, Gerhard; Hei, Tom K; Brenner, David J

    2015-03-01

    A noninvasive, self-referencing biosensor/probe system has been integrated into the Columbia University Radiological Research Accelerator Facility Microbeam II end station. A single-cell oxygen consumption measurement has been conducted with this type of oxygen probe in 37° C Krebs-Ringer Bicarbonate buffer immediately before and after a single-cell microbeam irradiation. It is the first such measurement made for a microbeam irradiation, and a six fold increment of oxygen flux induced during a 15-s period of time has been observed following radiation exposure. The experimental procedure and the results are discussed.

  15. MODELING NITROGEN-CARBON CYCLING AND OXYGEN CONSUMPTION IN BOTTOM SEDIMENTS

    EPA Science Inventory

    A model framework is presented for simulating nitrogen and carbon cycling at the sediment–water interface, and predicting oxygen consumption by oxidation reactions inside the sediments. Based on conservation of mass and invoking simplifying assumptions, a coupled system of diffus...

  16. Measuring instrument for the determination of the oxygen consumption of scuba divers in open waters.

    PubMed

    McNeill, A W

    1979-07-01

    An apparatus is described for the estimation of incremental oxygen consumption and carbon-dioxide production of SCUBA divers working in the field. Air is supplied to the diver in discrete volumes, and aliquots of respired air collected from each discrete time interval.

  17. Mapping cerebral glutamate 13C turnover and oxygen consumption by in vivo NMR.

    PubMed

    Hyder, Fahmeed; Brown, Peter; Nixon, Terennce W; Behar, Kevin L

    2003-01-01

    Regional rates of 13C incorporation from glucose to glutamate were detected in anesthetized rat brain in vivo at 7T with high temporal and spatial resolution using NMR method ICED PEPSI (in vivo carbon edited detection with proton echo planar spectroscopic imaging). Time courses of regional glutamate 13C turnover were fitted by a metabolic model to obtain regional tri-carboxylic acid (TCA) cycle flux and cerebral metabolic rate of oxygen consumption (CMRO2) in each voxel (8 microL) of rat cortex. CMRO2 maps obtained for rats under either alpha-chloralose or morphine anesthesia revealed average cortical values of 1.5 +/- 0.2 (n = 3) and 3.2 +/- 0.3 (n = 4) mumol/g/min, respectively. These values of CMRO2 are in good agreement with previous cortical measurements with coarser spatial resolution. The heterogeneity within each map, which depicted predominantly gray and white matter differences, was significantly greater under morphine (higher cortical activity) than under-alpha-chloralose (lower cortical activity) anesthesia. The regional variations in the basal awake state, which are expected to be even greater, should be considered to avoid partial-volume artifacts in functional activation studies of awake subjects. PMID:14562702

  18. Local muscle oxygen consumption related to external and joint specific power.

    PubMed

    Skovereng, Knut; Ettema, Gertjan; van Beekvelt, Mireille

    2016-02-01

    The purpose of the present study was to examine the effects of external work rate on joint specific power and the relationship between knee extension power and vastus lateralis muscle oxygen consumption (mVO2). We measured kinematics and pedal forces and used inverse dynamics to calculate joint power for the hip, knee and ankle joints during an incremental cycling protocol performed by 21 recreational cyclists. Vastus lateralis mVO2 was estimated using near-infrared spectroscopy with an arterial occlusion. The main finding was a non-linear relationship between vastus lateralis mVO2 and external work rate that was characterised by an increase followed by a tendency for a levelling off (R(2)=0.99 and 0.94 for the quadratic and linear models respectively, p<0.05). When comparing 100W and 225W, there was a ∼43W increase in knee extension but still a ∼9% decrease in relative contribution of knee extension to external work rate resulting from a ∼47W increase in hip extension. When vastus lateralis mVO2 was related to knee extension power, the relationship was still non-linear (R(2)=0.99 and 0.97 for the quadratic and linear models respectively, p<0.05). These results demonstrate a non-linear response in mVO2 relative to a change in external work rate. Relating vastus lateralis mVO2 to knee extension power showed a better fit to a linear equation compared to external work rate, but it is not a straight line.

  19. Brain natriuretic peptide predicts forced vital capacity of the lungs, oxygen pulse and peak oxygen consumption in physiological condition.

    PubMed

    Popovic, Dejana; Ostojic, Miodrag C; Popovic, Bojana; Petrovic, Milan; Vujisic-Tesic, Bosiljka; Kocijancic, Aleksandar; Banovic, Marko; Arandjelovic, Aleksandra; Stojiljkovic, Stanimir; Markovic, Vidan; Damjanovic, Svetozar S

    2013-05-01

    Brain natriuretic peptide (NT-pro-BNP) is used as marker of cardiac and pulmonary diseases. However, the predictive value of circulating NT-pro-BNP for cardiac and pulmonary performance is unclear in physiological conditions. Standard echocardiography, tissue Doppler and forced spirometry at rest were used to assess cardiac parameters and forced vital capacity (FVC) in two groups of athletes (16 elite male wrestlers (W), 21 water polo player (WP)), as different stress adaptation models, and 20 sedentary subjects (C) matched for age. Cardiopulmonary test on treadmill (CPET), as acute stress model, was used to measure peak oxygen consumption (peak VO2), maximal heart rate (HRmax) and peak oxygen pulse (peak VO2/HR). NT-pro-BNP was measured by immunoassey sandwich technique 10min before the test - at rest, at the beginning of the test, at maximal effort, at third minute of recovery. FVC was higher in athletes and the highest in W (WP 5.60±0.29 l; W 6.57±1.00 l; C 5.41±0.29 l; p<0.01). Peak VO2 and peak VO2/HR were higher in athletes and the highest in WP. HRmax was not different among groups. In all groups, NT-pro-BNP decreased from rest to the beginning phase, increased in maximal effort and stayed unchanged in recovery. NT-pro-BNP was higher in C than W in all phases; WP had similar values as W and C. On multiple regression analysis, in all three groups together, ΔNT-pro-BNP from rest to the beginning phase independently predicted both peak VO2 and peak VO2/HR (r=0.38, 0.35; B=37.40, 0.19; p=0.007, 0.000, respectively). NT-pro-BNP at rest predicted HRmax (r=-0.32, B=-0.22, p=0.02). Maximal NT-pro-BNP predicted FVC (r=-0.22, B=-0.07, p=0.02). These results show noticeable predictive value of NT-pro-BNP for both cardiac and pulmonary performance in physiological conditions suggesting that NT-pro-BNP could be a common regulatory factor coordinating adaptation of heart and lungs to stress condition.

  20. Biomass burning fuel consumption rates: a field measurement database

    NASA Astrophysics Data System (ADS)

    van Leeuwen, T. T.; van der Werf, G. R.; Hoffmann, A. A.; Detmers, R. G.; Rücker, G.; French, N. H. F.; Archibald, S.; Carvalho, J. A., Jr.; Cook, G. D.; de Groot, W. J.; Hély, C.; Kasischke, E. S.; Kloster, S.; McCarty, J. L.; Pettinari, M. L.; Savadogo, P.; Alvarado, E. C.; Boschetti, L.; Manuri, S.; Meyer, C. P.; Siegert, F.; Trollope, L. A.; Trollope, W. S. W.

    2014-06-01

    Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. These fuel consumption (FC) rates depend on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC rates are either modeled or taken selectively from the literature. We compiled the peer-reviewed literature on FC rates for various biomes and fuel categories to better understand FC rates and variability, and to provide a~database that can be used to constrain biogeochemical models with fire modules. We compiled in total 76 studies covering 10 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha-1), tropical forest (n = 19, FC = 126), temperate forest (n = 11, FC = 93), boreal forest (n = 16, FC = 39), pasture (n = 6, FC = 28), crop residue (n = 4, FC = 6.5), chaparral (n = 2, FC = 32), tropical peatland (n = 4, FC = 314), boreal peatland (n = 2, FC = 42), and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e.g. only 3 measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences were found within the defined biomes: for example FC rates of temperate pine forests in the USA were 38% higher than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC rates, not only between biomes but also within biomes and fuel classes. This implies that care should be taken with using averaged values, and our comparison with FC rates from GFED3 indicates that also modeling studies have difficulty in representing the dynamics governing FC.

  1. In vitro culture and oxygen consumption of NSCs in size-controlled neurospheres of Ca-alginate/gelatin microbead.

    PubMed

    Song, Kedong; Yang, Yanfei; Li, Shixiao; Wu, Meiling; Wu, Yixing; Lim, Mayasari; Liu, Tianqing

    2014-07-01

    Neural stem cells (NSCs) forming neurospheres in a conventional culture tend to develop necrotic/apoptotic centers due to mass transport limitations. In this study, the internal pore structure of calcium-alginate/gelatin (CAG) microbeads was tuned and controlled to provide a suitable three-dimensional environment supporting NSC proliferation. Direct impact of three-dimensional space availability was quantified by oxygen consumption rates of NSCs and cells were cultured in three different methods: neurospheres, single cell suspension of NSCs, and encapsulated NSCs in microbeads. Our results showed that encapsulated NSCs in CAG microbeads maintained higher cell viability than in conventional culture. In addition, NSCs encapsulated in CAG microbeads preserved their original stemness and continued to express nestin, CNPase, GFAP and β-tubulin-III post-encapsulation. Oxygen consumption rates of encapsulated NSCs in CAG microbeads were the lowest as compared to the other two culture methods. The optimal cell density supporting high cell proliferation in CAG microbeads was found to be 1.5×10(5)cells/mL. The glucose consumption curve suggests that encapsulated NSCs in microbeads had a slower growth profile. This study presents an alternative method in hybrid microbead preparation to generate a highly favorable three-dimensional cell carrier for NSCs and was successfully applied for its effective in vitro expansion.

  2. Modelling Oxygen Dynamics in an Intermittently Stratified Estuary: Estimation of Process Rates Using Field Data

    NASA Astrophysics Data System (ADS)

    Borsuk, M. E.; Stow, C. A.; Luettich, R. A.; Paerl, H. W.; Pinckney, J. L.

    2001-01-01

    The relationship between bottom water dissolved oxygen concentration, vertical stratification, and temperature was investigated for the Neuse River estuary, North Carolina, a shallow, intermittently-mixed estuary using approximately 10 years of weekly/biweekly, mid-channel data. A generalized additive model (GAM) was used to initially explore the major relationships among observed variables. The results of this statistical model guided the specification of a process-based model of oxygen dynamics that is consistent with theory yet simple enough to be parameterized using available field data. The nonlinear optimization procedure employed allows for the direct estimation of microbial oxygen consumption and physical reoxygenation rates, including the effects of temperature and vertical stratification. These estimated rates may better represent aggregate system behaviour than closed chamber measurements made in the laboratory and in situ. The resulting model describes 79% of the variation in dissolved oxygen concentration and is robust when compared across separate locations and time periods. Model predictions suggest that the spatial extent and duration of hypoxia in the bottom waters of the Neuse are controlled by the balance between the net oxygen depletion rate and the frequency of vertical mixing events. During cool months, oxygen consumption rates remain low enough to keep oxygen concentration well above levels of concern even under extended periods of stratification. A concentration below 4 mg l -1is only expected under extended periods without vertical mixing when bottom water temperature exceeds 15 °C, while a concentration below 2 mg l -1is only expected when water temperature exceeds 20 °C. To incorporate the effects of parameter uncertainty, model error, and natural variability on model prediction, we used Monte Carlo simulation to generate distributions for the predicted number of days of hypoxia during the summer season. The expected number of days with

  3. Fish Consumption, Sleep, Daily Functioning, and Heart Rate Variability

    PubMed Central

    Hansen, Anita L.; Dahl, Lisbeth; Olson, Gina; Thornton, David; Graff, Ingvild E.; Frøyland, Livar; Thayer, Julian F.; Pallesen, Staale

    2014-01-01

    Study Objectives: This study investigated the effects of fatty fish on sleep, daily functioning and biomarkers such as heart rate variability (HRV), vitamin D status (serum 25-hydroxyvitamin D (25OHD), and eicosapentaenoic acid (EPA, 20:5n-3) + docosahexaenoic acid (DHA, 22:6n-3) in red blood cells. Moreover the relationship among sleep, daily functioning, HRV, vitamin D status, and levels of EPA+DHA was investigated. Methods: Ninety-five male forensic patients from a secure forensic inpatient facility in the USA were randomly assigned into a Fish or a Control group. The Fish group received Atlantic salmon three times per week from September to February, and the Control group was provided an alternative meal (e.g., chicken, pork, beef), but with the same nutritional value as their habitual diet, three times per week during the same period. Sleep (sleep latency, sleep efficiency, actual sleep time, and actual wake time), self-perceived sleep quality and daily functioning, as well as vitamin D status, EPA+DHA, and HRV, were assessed pre- and post-intervention period. Results: There was a significant increase in sleep latency from pre- to post-test in the Control group. The Fish group reported better daily functioning than the Control group during post-test. Fish consumption throughout the wintertime had also an effect on resting HRV and EPA+DHA, but not on vitamin D status. However, at post-test, the vitamin D status in the Fish group was still closer to the level regarded as optimal compared to the Control group. Vitamin D status correlated negatively with actual wake time and positively with sleep efficiency during pre-test, as well as positively with daily functioning and sleep quality during post-test. Finally, HRV correlated negatively with sleep latency and positively with daily functioning. Conclusions: Fish consumption seemed to have a positive impact on sleep in general and also on daily functioning, which may be related to vitamin D status and HRV. Citation

  4. Fractional consumption of liquid hydrogen and liquid oxygen during the space shuttle program

    NASA Astrophysics Data System (ADS)

    Partridge, Jonathan K.

    2012-06-01

    The Space Shuttle uses the propellants, liquid hydrogen and liquid oxygen, to meet part of the propulsion requirements from ground to orbit. The Kennedy Space Center procured over 350 million liters of liquid hydrogen and over 200 million liters of liquid oxygen during the 30-year Space Shuttle Program. Because of the nature of the cryogenic propellants, approximately 54% of the total purchased liquid hydrogen and 32% of the total purchased liquid oxygen were used in the Space Shuttle Main Engines. The balance of the propellants were vaporized during operations for various purposes. This paper dissects the total consumption of liquid hydrogen and liquid oxygen and determines the fraction attributable to each of the various processing and launch operations that occurred during the entire Space Shuttle Program at the Kennedy Space Center.

  5. Fractional Consumption of Liquid Hydrogen and Liquid Oxygen During the Space Shuttle Program

    NASA Technical Reports Server (NTRS)

    Partridge, Jonathan K.

    2011-01-01

    The Space Shuttle uses the propellants, liquid hydrogen and liquid oxygen, to meet part of the propulsion requirements from ground to orbit. The Kennedy Space Center procured over 25 million kilograms of liquid hydrogen and over 250 million kilograms of liquid oxygen during the 3D-year Space Shuttle Program. Because of the cryogenic nature of the propellants, approximately 55% of the total purchased liquid hydrogen and 30% of the total purchased liquid oxygen were used in the Space Shuttle Main Engines. The balance of the propellants were vaporized during operations for various purposes. This paper dissects the total consumption of liqUid hydrogen and liqUid oxygen and determines the fraction attributable to each of the various processing and launch operations that occurred during the entire Space Shuttle Program at the Kennedy Space Center.

  6. Modeling oxygen consumption in the proximal tubule: effects of NHE and SGLT2 inhibition.

    PubMed

    Layton, Anita T; Vallon, Volker; Edwards, Aurélie

    2015-06-15

    The objective of this study was to investigate how physiological, pharmacological, and pathological conditions that alter sodium reabsorption (TNa) in the proximal tubule affect oxygen consumption (QO2 ) and Na(+) transport efficiency (TNa/QO2 ). To do so, we expanded a mathematical model of solute transport in the proximal tubule of the rat kidney. The model represents compliant S1, S2, and S3 segments and accounts for their specific apical and basolateral transporters. Sodium is reabsorbed transcellularly, via apical Na(+)/H(+) exchangers (NHE) and Na(+)-glucose (SGLT) cotransporters, and paracellularly. Our results suggest that TNa/QO2 is 80% higher in S3 than in S1-S2 segments, due to the greater contribution of the passive paracellular pathway to TNa in the former segment. Inhibition of NHE or Na-K-ATPase reduced TNa and QO2 , as well as Na(+) transport efficiency. SGLT2 inhibition also reduced proximal tubular TNa but increased QO2 ; these effects were relatively more pronounced in the S3 vs. the S1-S2 segments. Diabetes increased TNa and QO2 and reduced TNa/QO2 , owing mostly to hyperfiltration. Since SGLT2 inhibition lowers diabetic hyperfiltration, the net effect on TNa, QO2 , and Na(+) transport efficiency in the proximal tubule will largely depend on the individual extent to which glomerular filtration rate is lowered.

  7. Modeling oxygen consumption in the proximal tubule: effects of NHE and SGLT2 inhibition

    PubMed Central

    Vallon, Volker; Edwards, Aurélie

    2015-01-01

    The objective of this study was to investigate how physiological, pharmacological, and pathological conditions that alter sodium reabsorption (TNa) in the proximal tubule affect oxygen consumption (QO2) and Na+ transport efficiency (TNa/QO2). To do so, we expanded a mathematical model of solute transport in the proximal tubule of the rat kidney. The model represents compliant S1, S2, and S3 segments and accounts for their specific apical and basolateral transporters. Sodium is reabsorbed transcellularly, via apical Na+/H+ exchangers (NHE) and Na+-glucose (SGLT) cotransporters, and paracellularly. Our results suggest that TNa/QO2 is 80% higher in S3 than in S1–S2 segments, due to the greater contribution of the passive paracellular pathway to TNa in the former segment. Inhibition of NHE or Na-K-ATPase reduced TNa and QO2, as well as Na+ transport efficiency. SGLT2 inhibition also reduced proximal tubular TNa but increased QO2; these effects were relatively more pronounced in the S3 vs. the S1–S2 segments. Diabetes increased TNa and QO2 and reduced TNa/QO2, owing mostly to hyperfiltration. Since SGLT2 inhibition lowers diabetic hyperfiltration, the net effect on TNa, QO2, and Na+ transport efficiency in the proximal tubule will largely depend on the individual extent to which glomerular filtration rate is lowered. PMID:25855513

  8. Selection for high and low oxygen consumption altered hepatic mitochondrial energy efficiency in mice.

    PubMed

    Hong, Yu; Ardiyanti, Astrid; Kikusato, Motoi; Shimazu, Tomoyuki; Toyomizu, Masaaki; Suzuki, Keiichi

    2015-09-01

    Selection for high (H) and low (L) oxygen consumption (OC) as an indirect estimation of maintenance energy requirement was determined. Feed intake and body weight were measured and feed conversion ratio (FCR) of 4-8-week-old mice was calculated. Respiratory activity of hepatic mitochondria was measured at 12 weeks. Total feed intake (H: 103.74 g, L: 97.92 g, P < 0.01), daily feed intake (H: 3.70 g/day, L: 3.50 g/day, P < 0.01) and FCR (H: 18.79, L: 15.50, P < 0.01) were significantly different between lines. The line by sex interaction was significant for FCR. No line differences were observed in males; and the FCR of the H line was greater than in the L line in females. H line mice had the highest hepatic mitochondrial respiratory activity in state 2 (P < 0.01), the highest uncoupled respiratory rate of mitochondria in the presence of an uncoupling agent (P < 0.001), and the mitochondrial proton leak. The adenosine diphosphate/ O ratio was highest in the L line (P < 0.05). This suggests that the selection for high and low OC induced differences in basal mitochondrial respiration and basal metabolism, resulting in difference in FCR between H and L lines.

  9. Stimulation of oxygen consumption of platelets by Solcoseryl and cardiocrome during in vitro aging for 5 days.

    PubMed

    Shimizu, T

    1990-08-01

    Solcoseryl (SOL) and Cardiocrome (CAR) produced decreases in the partial oxygen pressure of platelet suspensions, indicating the acceleration of platelet oxygen consumption. However, the peak response to CAR was much faster than that to SOL. Application of 1 ml of SOL to 20 ml of platelet suspension stored for 1 day produced increases of 1 nmol ATP per min per 10(9) platelets. The same increases in oxygen consumption appeared after 3 or 5 day-storage.

  10. Intermediates of Krebs cycle correct the depression of the whole body oxygen consumption and lethal cooling in barbiturate poisoning in rat.

    PubMed

    Ivnitsky, Jury Ju; Schäfer, Timur V; Malakhovsky, Vladimir N; Rejniuk, Vladimir L

    2004-10-01

    Rats poisoned with one LD50 of thiopental or amytal are shown to increase oxygen consumption when intraperitoneally given sucinate, malate, citrate, alpha-ketoglutarate, dimethylsuccinate or glutamate (the Krebs cycle intermediates or their precursors) but not when given glucose, pyruvate, acetate, benzoate or nicotinate (energy substrates of other metabolic stages etc). Survival was increased with succinate or malate from control groups, which ranged from 30-83% to 87-100%. These effects were unrelated to respiratory depression or hypoxia as judged by little or no effect of succinate on ventilation indices and by the lack of effect of oxygen administration. Body cooling of comatose rats at ambient temperature approximately 19 degrees C became slower with succinate, the rate of cooling correlated well with oxygen consumption decrease. Succinate had no potency to modify oxygen consumption and body temperature in intact rats. A condition for antidote effect of the Krebs intermediate was sufficiently high dosage (5 mmol/kg), further dose increase made no odds. Repeated dosing of succinate had more marked protective effect, than a single one, to oxygen consumption and tended to promote the attenuation of lethal effect of barbiturates. These data suggest that suppression of whole body oxygen consumption with barbiturate overdose could be an important contributor to both body cooling and mortality. Intermediates of Krebs cycle, not only succinate, may have a pronounced therapeutic effect under the proper treatment regimen. Availability of Krebs cycle intermediates may be a limiting factor for the whole body oxygen consumption in barbiturate coma, its role in brain needs further elucidation.

  11. Locomotor-respiratory coupling patterns and oxygen consumption during walking above and below preferred stride frequency.

    PubMed

    O'Halloran, Joseph; Hamill, Joseph; McDermott, William J; Remelius, Jebb G; Van Emmerik, Richard E A

    2012-03-01

    Locomotor respiratory coupling patterns in humans have been assessed on the basis of the interaction between different physiological and motor subsystems; these interactions have implications for movement economy. A complex and dynamical systems framework may provide more insight than entrainment into the variability and adaptability of these rhythms and their coupling. The purpose of this study was to investigate the relationship between steady state locomotor-respiratory coordination dynamics and oxygen consumption [Formula: see text] of the movement by varying walking stride frequency from preferred. Twelve male participants walked on a treadmill at a self-selected speed. Stride frequency was varied from -20 to +20% of preferred stride frequency (PSF) while respiratory airflow, gas exchange variables, and stride kinematics were recorded. Discrete relative phase and return map techniques were used to evaluate the strength, stability, and variability of both frequency and phase couplings. Analysis of [Formula: see text] during steady-state walking showed a U-shaped response (P = 0.002) with a minimum at PSF and PSF - 10%. Locomotor-respiratory frequency coupling strength was not greater (P = 0.375) at PSF than any other stride frequency condition. The dominant coupling across all conditions was 2:1 with greater occurrences at the lower stride frequencies. Variability in coupling was the greatest during PSF, indicating an exploration of coupling strategies to search for the coupling frequency strategy with the least oxygen consumption. Contrary to the belief that increased strength of frequency coupling would decrease oxygen consumption; these results conclude that it is the increased variability of frequency coupling that results in lower oxygen consumption.

  12. The rate of oxygen isotope exchange between nitrate and water

    NASA Astrophysics Data System (ADS)

    Kaneko, Masanori; Poulson, Simon R.

    2013-10-01

    The oxygen isotope exchange rate between nitrate and water was measured at a temperature of 50-80 °C and pH -0.6 to 1.1. Oxygen isotope exchange is a first-order reaction, with the exchange rate being strongly affected by both reaction temperature and pH, with increased rates of isotope exchange at higher temperatures and lower pH values. The rate of oxygen isotope exchange under natural conditions is extremely slow, with an estimated half-life for isotope exchange of 5.5 × 109 years at 25 °C and pH 7. The extremely slow rate of oxygen isotope exchange between nitrate and water under typical environmental conditions illustrates that nitrate-δ18O signatures (and also nitrate δ17O and Δ17O signatures) associated with various nitrate sources, as well as isotope compositions produced by biogeochemical processes, will be preserved. Hence, it is valid to use the value of nitrate-δ18O to investigate the sources and biogeochemical behavior of nitrate, in a similar manner to the use of sulfate-δ18O signatures to study the sources and biogeochemical behavior of sulfate. Equilibrium oxygen isotope fractionation factors have been determined, although quantification of the nitrate-water equilibrium fractionation factor is not possible due to the presence of nitrate as both protonated (i.e. HNO3) and unprotonated forms (i.e. NO3-) under the experimental conditions, and the difficulty in accurately calculating nitrate speciation in low pH, high ionic strength solutions.

  13. Effect of live weight gain of steers during winter grazing: II. Visceral organ mass, cellularity, and oxygen consumption.

    PubMed

    Hersom, M J; Krehbiel, C R; Horn, G W

    2004-01-01

    Two experiments were conducted to examine the effect of BW gain during winter grazing on mass, cellularity, and oxygen consumption of splanchnic tissues before and after the feedlot finishing phase. In each experiment, 48 fall-weaned Angus x Angus-Hereford steer calves were assigned randomly to one of three treatments: 1) high rate of BW gain grazing winter wheat (HGW), 2) low rate of BW gain grazing winter wheat (LGW), or 3) grazing dormant tallgrass native range supplemented with 0.91 kg/d of a 41% CP supplement (NR). At the end of winter grazing, four steers were selected randomly from each treatment for initial slaughter to measure organ mass, cellularity, and oxygen consumption. All remaining steers were placed into a feedlot and fed to the same backfat end point (1.27 cm). Six steers were selected randomly from each treatment for final organ mass, cellularity, and oxygen consumption. Initial empty BW (EBW) was greatest (P < 0.001) for HGW, intermediate for LGW, and least for NR steers in both Exp. 1 and 2 (355 > 263 > 207 +/- 6.5 kg and 337 > 274 > 205 +/- 8.7 kg, respectively). For both experiments, the initial total gastrointestinal tract (GIT; g/kg of EBW) proportional weight was greater (P < 0.05) in NR steers than in LGW, and LGW steers had greater (P < 0.05) initial GIT proportional weight than HGW steers. Proportional weight of total splanchnic tissues (TST; g/kg of EBW) did not differ (P < 0.19) among treatments. Initial duodenal RNA concentration and RNA:protein were greater (P < 0.02) in LGW than in HGW steers, and NR steers were intermediate. Initial in vitro liver O2 consumption was greater (P < 0.09) in HGW and LGW than in NR steers (34.5 > 16.9 mL/min), whereas initial small intestinal oxygen consumption was greater (P < 0.01) in LGW than in HGW and NR steers (12.1 > 5.2 mL/min). Ruminal papillae oxygen consumption did not differ (P < 0.55) among treatments. The rate of decrease of GIT (g x g EBW(-1) x d(-1)) during finishing was greater in NR

  14. Oxygen consumption and temperature control of premature infants in a double-wall incubator.

    PubMed

    Marks, K H; Lee, C A; Bolan, C D; Maisels, M J

    1981-07-01

    The effects of a double wall in a forced convection-heated incubator were studied on ten naked, nondistressed, premature infants by measuring their mean skin temperature, esophageal temperature, and oxygen consumption when they were in thermal steady state, with, and without, the double wall in place. The incubator air temperature was maintained within the recommended thermoneutral zone during the consecutive paired experiments. Ambient room temperature and relative humidity were constant and the infant's activity (quiet sleep) and postprandial state were the same in both conditions. Together with a significant rise in operative temperature (P less than .05) induced by the double wall (accounted for by a 0.9 C mean increased in incubator wall temperature nearest the baby), their mean skin temperature and esophageal temperatures increased (P less than .025), while a decrease in oxygen consumption occurred in nine of the ten infants (P less than .05). These findings suggest that the double wall reduced radiant and total heat loss from the baby by diminishing the temperature gradient between the skin and incubator surfaces and that metabolic heat production (oxygen consumption) was reduced when the double wall was in place.

  15. Resting oxygen consumption of premature infants covered with a plastic thermal blanket.

    PubMed

    Darnall, R A; Ariagno, R L

    1979-04-01

    Premature infants in single-wall incubators covered with "thermal blankets" made of plastic packing material have large reductions in insensible water loss (IWL) compared with naked infants. We postulated that such reductions inevaporative heat loss would not result in decreases in caloric expenditure if body temperature were maintained by a servocontrolled heat source. Using an open-circuit technique, we measured oxygen consumption (VO2), carbon dioxide production (VCO2), heart rate (HR), respiratory rate (RR), and abdominal skin (Tabd), cheek, thigh, rectal, incubator air, wall, and room air temperatures in ten infants less than 37 weeks gestational age and from 2 to 24 days of age both naked and covered with a plastic thermal blanket. Tabd temperature was maintained between 36.2 and 36.8 C and rectal temperature between 36.8 and 37.2 C in each environment by manual or automatic servocontrol. A "resting state" was defined by using a combination of subjective and objective criteria. The mean values of VO2 during the "resting state" were 7.31 and 7.59 cc/kg of body weight per minute for naked and covered infants, respectively. There were no significant differences between mean values of VCO2, respiratory quotient, HR, RR, abdominal, cheek, thigh, or rectal temperatures in the two environments. Operant temperatures averaged 0.5 C lower when the infants were covered. These data support the hypothesis that decreases in insensible water loss do not necessarily imply reductions in caloric requirements in infants where Tabd is maintained by servocontrol. PMID:440864

  16. Oxygen Mass Flow Rate Generated for Monitoring Hydrogen Peroxide Stability

    NASA Technical Reports Server (NTRS)

    Ross, H. Richard

    2002-01-01

    Recent interest in propellants with non-toxic reaction products has led to a resurgence of interest in hydrogen peroxide for various propellant applications. Because peroxide is sensitive to contaminants, material interactions, stability and storage issues, monitoring decomposition rates is important. Stennis Space Center (SSC) uses thermocouples to monitor bulk fluid temperature (heat evolution) to determine reaction rates. Unfortunately, large temperature rises are required to offset the heat lost into the surrounding fluid. Also, tank penetration to accomodate a thermocouple can entail modification of a tank or line and act as a source of contamination. The paper evaluates a method for monitoring oxygen evolution as a means to determine peroxide stability. Oxygen generation is not only directly related to peroxide decomposition, but occurs immediately. Measuring peroxide temperature to monitor peroxide stability has significant limitations. The bulk decomposition of 1% / week in a large volume tank can produce in excess of 30 cc / min. This oxygen flow rate corresponds to an equivalent temperature rise of approximately 14 millidegrees C, which is difficult to measure reliably. Thus, if heat transfer were included, there would be no temperature rise. Temperature changes from the surrounding environment and heat lost to the peroxide will also mask potential problems. The use of oxygen flow measurements provides an ultra sensitive technique for monitoring reaction events and will provide an earlier indication of an abnormal decomposition when compared to measuring temperature rise.

  17. New oxygen-fuel burner significantly improves electric arc furnace productivity with less energy consumption

    SciTech Connect

    Untz, J.; Knowles, D.

    1984-11-01

    This article describes a new system of electric arc steelmaking based on use of oxygen with newly designed burner for increased productivity and reduced energy consumption. The need for the oxygen-fuel burner has been recognized for years. Because of the shape of the flux lines of the arc between electrodes, some areas receive much more heat than others and consequently melt faster, leaving portions of the furnace charge unmelted for some time. Until these cold areas are melted into the bath, the arcing process must continue in a less efficient mode, delaying the completion of the process and therefore reducing productivity and using more energy. Steelmakers have been looking for a heat source to apply to these cold areas so that all material would melt at the same time. The oxygen-fuel burner was chosen because of its ability to deliver a directed flame at temperatures nearing 5000/sup 0/F.

  18. Oxygen consumption and distribution in the Long-Evans rat retina

    PubMed Central

    Lau, Jennifer C.M.; Linsenmeier, Robert A.

    2012-01-01

    The purpose of this study was to investigate the oxygen distribution and consumption in the pigmented Long-Evans rat retina in vivo during dark and light adaptation, and to compare these results to previous work on cat and albino rat. Double-barreled microelectrodes recorded both intraretinal PO2 depth profiles and the electroretinogram (ERG), which was used to identify the boundaries of the retina. Light adaptation decreased photoreceptor oxygen consumption per unit volume (Qav) from 3.0±0.4 ml•100 g−1•min−1 (mean ± SEM) in darkness to 1.8±0.2 ml•100 g−1•min−1 and increased minimum outer retinal PO2 at the inner segments (Pmin) from 17.4±3.0 to 29.9±5.3 mmHg. The effects of light on outer retinal PO2 and Qav were similar to those previously observed in cat, monkey, and albino rats; however, dark-adapted Pmin was higher in rat than cat. The parameters derived from fitting the oxygen diffusion model to the rat data were compared to those from cat. Oxygen consumption of the inner segments (Q2) and choroidal PO2 (PC) in rat and cat were similar. Pmin was higher in rat than in cat for two reasons: first, rat photoreceptors have a shorter oxygen consuming region; and second, the retinal circulation supplied a greater fraction of consumed oxygen to rat photoreceptors. The average PO2 across the inner retina (PIR) was not different in dark adaptation (25.4±4.8 mm Hg) and light adaptation (28.8±5.4 mmHg) when measured from PO2 profiles. However, with the microelectrode stationary at 9–18% retinal depth, a small consistent decrease in PO2 occurred during illumination. Flickering light at 6 Hz decreased inner retinal PO2 significantly more than an equivalent steady illumination, suggesting that changes in blood flow did not completely compensate for increased metabolism. This study comprehensively characterized rat retinal oxygenation in both light and dark, and determined the similarities and differences between rat and cat retinas. PMID:22828049

  19. Predicted consequences of diabetes and SGLT inhibition on transport and oxygen consumption along a rat nephron.

    PubMed

    Layton, Anita T; Vallon, Volker; Edwards, Aurélie

    2016-06-01

    Diabetes increases the reabsorption of Na(+) (TNa) and glucose via the sodium-glucose cotransporter SGLT2 in the early proximal tubule (S1-S2 segments) of the renal cortex. SGLT2 inhibitors enhance glucose excretion and lower hyperglycemia in diabetes. We aimed to investigate how diabetes and SGLT2 inhibition affect TNa and sodium transport-dependent oxygen consumption [Formula: see text] along the whole nephron. To do so, we developed a mathematical model of water and solute transport from the Bowman space to the papillary tip of a superficial nephron of the rat kidney. Model simulations indicate that, in the nondiabetic kidney, acute and chronic SGLT2 inhibition enhances active TNa in all nephron segments, thereby raising [Formula: see text] by 5-12% in the cortex and medulla. Diabetes increases overall TNa and [Formula: see text] by ∼50 and 100%, mainly because it enhances glomerular filtration rate (GFR) and transport load. In diabetes, acute and chronic SGLT2 inhibition lowers [Formula: see text] in the cortex by ∼30%, due to GFR reduction that lowers proximal tubule active TNa, but raises [Formula: see text] in the medulla by ∼7%. In the medulla specifically, chronic SGLT2 inhibition is predicted to increase [Formula: see text] by 26% in late proximal tubules (S3 segments), by 2% in medullary thick ascending limbs (mTAL), and by 9 and 21% in outer and inner medullary collecting ducts (OMCD and IMCD), respectively. Additional blockade of SGLT1 in S3 segments enhances glucose excretion, reduces [Formula: see text] by 33% in S3 segments, and raises [Formula: see text] by <1% in mTAL, OMCD, and IMCD. In summary, the model predicts that SGLT2 blockade in diabetes lowers cortical [Formula: see text] and raises medullary [Formula: see text], particularly in S3 segments. PMID:26764207

  20. Relationship between Maximal Oxygen Consumption (VO2max) and Home Range Area in Mammals.

    PubMed

    Albuquerque, Ralph L; Sanchez, Gabriela; Garland, Theodore

    2015-01-01

    Home range is defined as the area traversed during normal daily activities, such as foraging, avoiding predators, and social or antagonistic behaviors. All else being equal, larger home ranges should be associated with longer daily movement distances and/or higher average movement speeds. The maximal rate of oxygen consumption (VO2max) generally sets an upper limit to the intensity of work (e.g., speed of locomotion) that an animal can sustain without fatigue. Therefore, home range area and VO2max are predicted to evolve in concert (coadapt). We gathered literature data on home range and VO2max for 55 species of mammals. We computed residuals from log-log (allometric) regressions on body mass with two different regression models: ordinary least squares (OLS) and phylogenetic generalized least squares (PGLS). Residuals were weakly positively related for both the OLS (r = 0.278, one-tailed P < 0.05) and PGLS (r = 0.210, P > 0.05) regressions. For VO2max, the PGLS regression model had a slightly higher likelihood than the OLS model, but the situation was reversed for home range area. In addition, for both home range area and VO2max, models that fit better than either OLS or PGLS were obtained by modeling residual variation with the Ornstein-Uhlenbeck process to mimic stabilizing selection (RegOU), indicating that phylogenetic signal is present in both size-adjusted traits, consistent with findings of previous studies. (However, residuals from the RegOU models cannot be tested for correlation due to mathematical complexities.) We conclude that the best estimate of the residual correlation is probably somewhere between these two values reported above. Possible reasons for the low correlation between residual home range area and VO2max are discussed. PMID:26658413

  1. RSI: oxygen consumption, blood flow, and reoxygenation in patients suffering RSI measured by noninvasive optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Thijssen, Dick H. J.; van Uden, Caro J. T.; Krijgsman, Hans; Colier, Willy N. J. M.

    2003-07-01

    Background: Repetitive Strain Injury (RSI) is a major problem in nowadays health care and creates high financial costs and personal distress. Average prevalence rates in the Netherlands vary from 20-40% of the working population. Insight into the patho-physiological mechanism of RSI is important in order to establish adequate treatment and prevention programs. Objective: The aim of this study was to gain insight in muscle oxygen consumption (mVO2), blood flow (BF), and reoxygenation (ReOx) in the forearm of computer workers with stage III Repetitive Strain Injury (RSI). Method: We have used continuous wave infrared spectroscopy (NIRS) to measure these variables. Measurements were conducted on the extensor and flexor muscle in both arms as well in RSI-patients (n=10) as in control subjects (n=21). A protocol of increased isometric repetitive contraction in a handgrip ergonometer was used with increasing levels of strength. Results: mVO2 in the extensor muscle in RSI-subjects (dominant side) was increased compared to control subjects and compared to the non-dominant side (p<0.05). ReOx was not increased in RSI (dominant side-extensor muscle). However, there was a tendency towards statistical significance (p=0.065). BF in rest was equal in both groups, however after exercise it tended to be increased. Half-time recovery (T ») was measured during only one part of the protocol and it was significantly increased (p<0.05). Conclusion: mVO2 in RSI is impaired. BF and ReOx did not show difference between both groups. Future research should aim at a microvascular dysfunction in RSI.

  2. Atrial natriuretic peptide regulates lipid mobilization and oxygen consumption in human adipocytes by activating AMPK

    SciTech Connect

    Souza, Sandra C.; Chau, Mary D.L.; Yang, Qing; Gauthier, Marie-Soleil; Clairmont, Kevin B.; Wu, Zhidan; Gromada, Jesper; Dole, William P.

    2011-07-08

    Highlights: {yields} Treatment of differentiated human adipocytes with atrial natriuretic peptide (ANP) increased lipolysis and oxygen consumption by activating AMP-activated protein kinase (AMPK). {yields} ANP stimulated lipid mobilization by selective activation of the alpha2 subunit of AMPK and increased energy utilization through activation of both the alpha1 and alpha2 subunits of AMPK. {yields} ANP enhanced adipocyte mitochondrial oxidative capacity as evidenced by induction of oxidative mitochondrial genes and increase in oxygen consumption. {yields} Exposure of human adipocytes to fatty acids and (TNF{alpha}) induced insulin resistance and decreased expression of mitochondrial genes which was restored to normal by ANP. -- Abstract: Atrial natriuretic peptide (ANP) has been shown to regulate lipid and carbohydrate metabolism providing a possible link between cardiovascular function and metabolism by mediating the switch from carbohydrate to lipid mobilization and oxidation. ANP exerts a potent lipolytic effect via cGMP-dependent protein kinase (cGK)-I mediated-stimulation of AMP-activated protein kinase (AMPK). Activation of the ANP/cGK signaling cascade also promotes muscle mitochondrial biogenesis and fat oxidation. Here we demonstrate that ANP regulates lipid metabolism and oxygen utilization in differentiated human adipocytes by activating the alpha2 subunit of AMPK. ANP treatment increased lipolysis by seven fold and oxygen consumption by two fold, both of which were attenuated by inhibition of AMPK activity. ANP-induced lipolysis was shown to be mediated by the alpha2 subunit of AMPK as introduction of dominant-negative alpha2 subunit of AMPK attenuated ANP effects on lipolysis. ANP-induced activation of AMPK enhanced mitochondrial oxidative capacity as evidenced by a two fold increase in oxygen consumption and induction of mitochondrial genes, including carnitine palmitoyltransferase 1A (CPT1a) by 1.4-fold, cytochrome C (CytC) by 1.3-fold, and

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

    PubMed

    Paixão, S M; Anselmo, A M

    2002-01-01

    The test for inhibition of oxygen consumption by activated sludge (ISO 8192-1986 (E)) was evaluated as a tool for assessing, the acute toxicity of olive mill wastewaters (OMW). According to the ISO test, information generated by this method may be helpful in estimating the effect of a test material on bacterial communities in the aquatic environment, especially in aerobic biological treatment systems. However, the lack of standardized bioassay methodology for effluents imposed that the test conditions were modified and adapted. The experiments were conducted in the presence or absence of an easily biodegradable carbon source (glucose) with different contact times (20 min and 24 h). The results obtained showed a remarkable stimulatory effect of this effluent to the activated sludge microorganisms. In fact, the oxygen uptake rate values increase with increasing effluent concentrations and contact times up to 0.98 microl O(2) h(-1) mg(-1) dry weight for a 100% OMW sample, 24 h contact time, with blanks exhibiting an oxygen uptake rate of ca. 1/10 of this value (0.07-0.10). It seems that the application of the ISO test as an acute toxicity test for effluents should be reconsidered, with convenient adaptation for its utilization as a method of estimating the effect on bacterial communities present in aerobic biological treatment systems. PMID:12015797

  4. The effects of thermogenic agents on hindlimb oxygen consumption in the dog: ICI D7114 and noradrenaline.

    PubMed

    Gainer, J L; Briscoe, M G; Holloway, B R

    1993-01-15

    The thermogenic action of beta-adrenoceptor agonists may be due, in part, to increased metabolism in skeletal muscle. Previous results suggest that vasoconstriction is also necessary, and that the effect can be blocked by vasodilators. Both noradrenaline and the beta-3 agonist, ICI D7114, were studied using two dog hindlimb protocols. During constant perfusion conditions, ICI D7114 caused a significant increase in hindlimb oxygen consumption although it is a vasodilator. Noradrenaline resulted in a smaller rise in oxygen consumption, and produced a marked vasoconstriction. Both noradrenaline and ICI D7114 resulted in decreased oxygen consumption when the blood flow was allowed to vary in response to the drug treatment. The results suggest that changes in tissue oxygen consumption caused by beta-agonists are not related to vasomotion. PMID:8094057

  5. FEM-based oxygen consumption and cell viability models for avascular pancreatic islets

    PubMed Central

    Buchwald, Peter

    2009-01-01

    Background The function and viability of cultured, transplanted, or encapsulated pancreatic islets is often limited by hypoxia because these islets have lost their vasculature during the isolation process and have to rely on gradient-driven passive diffusion, which cannot provide adequate oxygen transport. Pancreatic islets (islets of Langerhans) are particularly susceptible due to their relatively large size, large metabolic demand, and increased sensitivity to hypoxia. Here, finite element method (FEM) based multiphysics models are explored to describe oxygen transport and cell viability in avascular islets both in static and in moving culture media. Methods Two- and three-dimensional models were built in COMSOL Multiphysics using the convection and diffusion as well as the incompressible Navier-Stokes fluid dynamics application modes. Oxygen consumption was assumed to follow Michaelis-Menten-type kinetics and to cease when local concentrations fell below a critical threshold; in a dynamic model, it was also allowed to increase with increasing glucose concentration. Results Partial differential equation (PDE) based exploratory cellular-level oxygen consumption and cell viability models incorporating physiologically realistic assumptions have been implemented for fully scaled cell culture geometries with 100, 150, and 200 μm diameter islets as representative. Calculated oxygen concentrations and intra-islet regions likely to suffer from hypoxia-related necrosis obtained for traditional flask-type cultures, oxygen-permeable silicone-rubber membrane bottom cultures, and perifusion chambers with flowing media and varying incoming glucose levels are presented in detail illustrated with corresponding colour-coded figures and animations. Conclusion Results of the computational models are, as a first estimate, in good quantitative agreement with existing experimental evidence, and they confirm that during culture, hypoxia is often a problem for non-vascularised islet

  6. Metformin overdose, but not lactic acidosis per se, inhibits oxygen consumption in pigs

    PubMed Central

    2012-01-01

    Introduction Hepatic mitochondrial dysfunction may play a critical role in the pathogenesis of metformin-induced lactic acidosis. However, patients with severe metformin intoxication may have a 30 to 60% decrease in their global oxygen consumption, as for generalized inhibition of mitochondrial respiration. We developed a pig model of severe metformin intoxication to validate this clinical finding and assess mitochondrial function in liver and other tissues. Methods Twenty healthy pigs were sedated and mechanically ventilated. Ten were infused with a large dose of metformin (4 to 8 g) and five were not (sham controls). Five others were infused with lactic acid to clarify whether lactic acidosis per se diminishes global oxygen use. Arterial pH, lactatemia, global oxygen consumption (VO2) (metabolic module) and delivery (DO2) (cardiac output by thermodilution) were monitored for nine hours. Oxygen extraction was computed as VO2/DO2. Activities of the main components of the mitochondrial respiratory chain (complex I, II and III, and IV) were measured with spectrophotometry (and expressed relative to citrate synthase activity) in heart, kidney, liver, skeletal muscle and platelets taken at the end of the study. Results Pigs infused with metformin (6 ± 2 g; final serum drug level 77 ± 45 mg/L) progressively developed lactic acidosis (final arterial pH 6.93 ± 0.24 and lactate 18 ± 7 mmol/L, P < 0.001 for both). Their VO2 declined over time (from 115 ± 34 to 71 ± 30 ml/min, P < 0.001) despite grossly preserved DO2 (from 269 ± 68 to 239 ± 51 ml/min, P = 0.58). Oxygen extraction accordingly fell from 43 ± 10 to 30 ± 10% (P = 0.008). None of these changes occurred in either sham controls or pigs infused with lactic acid (final arterial pH 6.86 ± 0.16 and lactate 22 ± 3 mmol/L). Metformin intoxication was associated with inhibition of complex I in the liver (P < 0.001), heart (P < 0.001), kidney (P = 0.003), skeletal muscle (P = 0.012) and platelets (P = 0

  7. Sodium cyanide induced alteration in the whole animal oxygen consumption and behavioural pattern of freshwater fish Labeo rohita.

    PubMed

    David, Muniswamy; Sangeetha, Jeyabalan; Harish, Etigemane R

    2015-03-01

    Sodium cyanide is a common environmental pollutant which is mainly used in many industries such as mining, electroplating, steel manufacturing, pharmaceutical production and other specialized applications including dyes and agricultural products. It enters aquatic environment through effluents from these industries. Static renewal bioassay test has been conducted to determine LC, of sodium cyanide on indigenous freshwater carp, Labeo rohita. The behavioural pattern and oxygen consumption were observed in fish at both lethal and sub lethal concentrations. Labeo rohita in toxic media exhibited irregular and erratic swimming movements, hyper excitability, loss of equilibrium and shrinking to the bottom, which may be due to inhibition of cytochrome C oxidase activity and decreased blood pH. The combination of cytotoxic hypoxia with lactate acidosis depresses the central nervous system resulting in respiratory arrest and death. Decrease in oxygen consumption was observed at both lethal and sub lethal concentrations of sodium cyanide. Mortality was insignificant at sub lethal concentration test when fishes were found under stress. Consequence of impaired oxidative metabolism and elevated physiological response by fish against sodium cyanide stress showed alteration in respiratory rate. PMID:25895263

  8. Growth, Oxygen Consumption, and Behavioral Responses of Danio rerio to Variation in Dietary Protein and Lipid Levels.

    PubMed

    O'Brine, Timothy M; Vrtělová, Jana; Snellgrove, Donna L; Davies, Simon J; Sloman, Katherine A

    2015-08-01

    In recent years, there has been increasing interest in the welfare of ornamental fish. Diet can significantly impact the welfare of fish, which can manifest as changes in the fish's physical health and behavior. The zebrafish, Danio rerio, is a popular ornamental species; however, little is known about their nutritional requirements with possible implications for their welfare. Here, we investigated the effect of diets with increasing crude protein (iso-caloric diets) and lipid (iso-nitrogenous diets) on the growth performance, oxygen consumption, and behavior of zebrafish. We found no significant effects of crude protein (32%-75%) or lipid (8%-16%) on the specific growth rate or oxygen consumption of fish fed 5% of their body mass (BM)/day, although the highest crude protein and lipid diet resulted in an increase in condition factor. Furthermore, the crude protein diets did not affect zebrafish behavior when fed a 2% BM ration, once a day. This study has shown that a diet with 32% crude protein and a diet with 8% crude lipid, when fed at a 5% BM ration, were sufficient to meet the growth requirements of our zebrafish. These diets supported the fish's physical health and thus benefited their welfare. PMID:26134575

  9. Benthic nutrient fluxes and sediment oxygen consumption in a full-scale facultative pond in Patagonia, Argentina.

    PubMed

    Faleschini, M; Esteves, J L

    2013-01-01

    The study of benthic metabolism is an interesting tool to understand the process that occurs in bottom water at wastewater stabilization ponds. Here, rates of benthic oxygen consumption and nutrient exchange across the water-sludge interface were measured in situ using a benthic chamber. The research was carried out during autumn, winter, and summer at a municipal facultative stabilization pond working in a temperate region (Puerto Madryn city, Argentina). Both a site near the raw wastewater inlet (Inlet station) and a site near the outlet (Outlet station) were sampled. Important seasonal and spatial patterns were identified as being related to benthic fluxes. Ammonium release ranged from undetectable (autumn/summer - Inlet station) to +30.7 kg-NH4(+) ha(-1) d(-1) (autumn - Outlet station), denitrification ranged from undetectable (winter - in both sites) to -4.0 kg-NO3(-) ha(-1) d(-1) (autumn - Outlet station), and oxygen consumption ranged from 0.07 kg-O2ha(-1) d(-1) (autumn/summer - Outlet station) to 0.84 kg-O2ha(-1) d(-1) (autumn - Inlet station). During the warmer months, the mineralization of organic matter from the bottom pond acts as a source of nutrients, which seem to support the important development of phytoplankton and nitrification activity recorded in the surface water. Bottom processes could be related to the advanced degree and efficiency of the treatment, the temperature, and probably the strong and frequent wind present in the region.

  10. Autonomic control of cardiac function and myocardial oxygen consumption during hypoxic hypoxia.

    NASA Technical Reports Server (NTRS)

    Erickson, H. H.; Stone, H. L.

    1972-01-01

    Investigation in 19 conscious dogs of the importance of the sympathetic nervous system in the coronary and cardiac response to altitude (hypoxic) hypoxia. Beta-adrenergic blockade was used to minimize the cardiac effect associated with sympathetic receptors. It is shown that the autonomic nervous system, and particularly the sympathetic nervous system, is responsible for the increase in ventricular function and myocardial oxygen consumption that occurs during hypoxia. Minimizing this response through appropriate conditioning and training may improve the operating efficiency of the heart and reduce the hazard of hypoxia and other environmental stresses, such as acceleration, which are encountered in advanced aircraft systems.

  11. 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

  12. Photosynthetic Potential and Light-Dependent Oxygen Consumption in a Benthic Cyanobacterial Mat

    PubMed Central

    Jørgensen, Bo Barker; Cohen, Yehuda; Revsbech, Niels Peter

    1988-01-01

    The potential to carry out oxygenic photosynthesis after prolonged burial below the photic zone was studied at 0.1-mm depth intervals in the thick, laminated Microcoleus chthonoplastes mats growing in Solar Lake, Sinai. The buried mat community lost about 20% of its photosynthetic potential with depth per annual layer down to 8- to 10-year-old layers at a 14-mm depth. In some of the older layers, below a 30-mm depth, light-dependent oxygen consumption which increased with increasing light intensity was observed. Possible mechanisms for this phenomenon are (i) pseudocyclic electron transport (Mehler reaction), (ii) interactions between respiratory electron transport and photosynthetic electron transport, (iii) photorespiration, and (iv) photooxidation. PMID:16347523

  13. Prediction of oxygen consumption in cardiac rehabilitation patients performing leg ergometry

    NASA Astrophysics Data System (ADS)

    Alvarez, John Gershwin

    The purpose of this study was two-fold. First, to determine the validity of the ACSM leg ergometry equation in the prediction of steady-state oxygen consumption (VO2) in a heterogeneous population of cardiac patients. Second, to determine whether a more accurate prediction equation could be developed for use in the cardiac population. Thirty-one cardiac rehabilitation patients participated in the study of which 24 were men and 7 were women. Biometric variables (mean +/- sd) of the participants were as follows: age = 61.9 +/- 9.5 years; height = 172.6 +/- 1.6 cm; and body mass = 82.3 +/- 10.6 kg. Subjects exercised on a MonarchTM cycle ergometer at 0, 180, 360, 540 and 720 kgm ˙ min-1. The length of each stage was five minutes. Heart rate, ECG, and VO2 were continuously monitored. Blood pressure and heart rate were collected at the end of each stage. Steady state VO 2 was calculated for each stage using the average of the last two minutes. Correlation coefficients, standard error of estimate, coefficient of determination, total error, and mean bias were used to determine the accuracy of the ACSM equation (1995). The analysis found the ACSM equation to be a valid means of estimating VO2 in cardiac patients. Simple linear regression was used to develop a new equation. Regression analysis found workload to be a significant predictor of VO2. The following equation is the result: VO2 = (1.6 x kgm ˙ min-1) + 444 ml ˙ min-1. The r of the equation was .78 (p < .05) and the standard error of estimate was 211 ml ˙ min-1. Analysis of variance was used to determine significant differences between means for actual and predicted VO2 values for each equation. The analysis found the ACSM and new equation to significantly (p < .05) under predict VO2 during unloaded pedaling. Furthermore, the ACSM equation was found to significantly (p < .05) under predict VO 2 during the first loaded stage of exercise. When the accuracy of the ACSM and new equations were compared based on

  14. ICI D7114 a novel selective beta-adrenoceptor agonist selectively stimulates brown fat and increases whole-body oxygen consumption.

    PubMed

    Holloway, B R; Howe, R; Rao, B S; Stribling, D; Mayers, R M; Briscoe, M G; Jackson, J M

    1991-09-01

    1. ICI D7114 is a novel, beta-adrenoceptor agonist which stimulates whole body oxygen consumption in conscious rats, cats and dogs and brown adipose tissue (BAT) activity in conscious rats. Treatment of rats with ICI D7114 stimulated oxygen consumption (ED50, 0.04 mg kg-1, p.o.) and BAT mitochondrial guanosine diphosphate (GDP)-binding (ED50, 0.15 mg kg-1, p.o.) with no chronotropic effects on the heart at these doses. 2. Reference beta-adrenoceptor agonists, isoprenaline and clenbuterol, also stimulated oxygen consumption and BAT activity but were less selective because they also produced effects on heart rate at these doses. 3. Treatment of conscious rats with ICI D7114 did not attenuate the chronotropic effects on the heart of a subsequent isoprenaline challenge. 4. Administration of ICI D7114 or of its acid metabolite had no effect in a cat soleus muscle model of tremor or on blood potassium levels in the conscious dog, indicating lack of effects at beta 2-adrenoceptors. 5. The results indicate that ICI D7114 may have activity at atypical beta-adrenoceptors in brown adipose tissue leading to increased whole body oxygen consumption. PMID:1686210

  15. ICI D7114 a novel selective beta-adrenoceptor agonist selectively stimulates brown fat and increases whole-body oxygen consumption.

    PubMed Central

    Holloway, B. R.; Howe, R.; Rao, B. S.; Stribling, D.; Mayers, R. M.; Briscoe, M. G.; Jackson, J. M.

    1991-01-01

    1. ICI D7114 is a novel, beta-adrenoceptor agonist which stimulates whole body oxygen consumption in conscious rats, cats and dogs and brown adipose tissue (BAT) activity in conscious rats. Treatment of rats with ICI D7114 stimulated oxygen consumption (ED50, 0.04 mg kg-1, p.o.) and BAT mitochondrial guanosine diphosphate (GDP)-binding (ED50, 0.15 mg kg-1, p.o.) with no chronotropic effects on the heart at these doses. 2. Reference beta-adrenoceptor agonists, isoprenaline and clenbuterol, also stimulated oxygen consumption and BAT activity but were less selective because they also produced effects on heart rate at these doses. 3. Treatment of conscious rats with ICI D7114 did not attenuate the chronotropic effects on the heart of a subsequent isoprenaline challenge. 4. Administration of ICI D7114 or of its acid metabolite had no effect in a cat soleus muscle model of tremor or on blood potassium levels in the conscious dog, indicating lack of effects at beta 2-adrenoceptors. 5. The results indicate that ICI D7114 may have activity at atypical beta-adrenoceptors in brown adipose tissue leading to increased whole body oxygen consumption. PMID:1686210

  16. Regional oxygen reduction and denitrification rates, San Joaquin Valley, USA

    NASA Astrophysics Data System (ADS)

    Green, C. T.; Jurgens, B. C.; Zhang, Y.; Starn, J. J.; Visser, A.; Singleton, M. J.; Esser, B. K.

    2015-12-01

    Rates of oxygen and nitrate reduction are key factors in determining the chemical evolution of groundwater. Little is known about how these rates vary in regional groundwater settings, as few studies have focused on regional datasets with multiple tracers and methods of analysis that account for effects of mixed residence times on apparent reaction rates. This study provides insight into residence times and rates of O2 reduction and denitrification using a novel approach of multi-model residence time distributions (RTDs) applied to a data set of atmospheric tracers of groundwater age and geochemical data from 141 well samples in the Central Eastern San Joaquin Valley, CA. The residence time distribution approach accounts for mixtures of residence times in a single sample to provide estimates of in-situ rates. Tracers included SF6, CFCs, 3H, He from 3H, 14C, and terrigenic He. Parameter estimation and multi-model averaging were used to establish RTDs with lower error variance than produced by individual RTD models. The set of multi-model RTDs was used in combination with NO3- and dissolved gas data to estimate zero order and first order rates of O2 reduction and denitrification. Results indicated that these rates followed approximately log-normal distributions. Rates of O2 reduction and denitrification were correlated and, on an electron milliequivalent basis, denitrification rates tended to exceed O2 reduction rates. Results indicate that the multi-model approach can improve estimation of age distributions, and that, because of the correlations, relatively easily measured O2 rates can provide information about trends in denitrification rates, which are more difficult to measure.

  17. A simple and portable paced step test for reproducible measurements of ventilation and oxygen consumption during exercise.

    PubMed Central

    Jones, P W; Wakefield, J M; Kontaki, E

    1987-01-01

    A single work rate paced step test is described. It was designed to allow the measurement of minute ventilation (VI) and oxygen consumption (VO2), under standardised conditions, during exercise in the clinic and lung function laboratory and in field work. The subjects and the operator found the test simple to perform. The values for ventilation at a given oxygen consumption were similar to those from more complex and stressful tests and had a high degree of reproducibility. The ergometer was a 12 inch (30 cm) step with hand rails. The subjects stepped down, once every four seconds in response to a buzzer for 10 minutes. VI and VO2 were measured with a small portable device. In 53 normal subjects of mean weight 69 (range 49-107) kg, mean VO2 measured during the last 5 minutes of the test was 0.89 (range 0.53-1.52) 1/min. Weight and height were independent contributors to the oxygen cost of stepping. The ventilatory equivalent for oxygen (VIO2, which equals VI divided by VO2) increased with age, and was similar to normal values for ventilation at 1.01/min VO2 obtained by workers who used multiple work rate tests on more complex equipment. The within subject variation in VIO2, expressed as the coefficient of variation (cv) and calculated for each age decade, was 14%. This again compared very favourably with the cv for values of ventilation at 1.01/min VO2 from other studies. In 20 normal subjects daily testing showed significant falls in VO2 and V1 over three days of 4% and 5.9% respectively; VIO2 fell by 2%. Testing over four consecutive weeks showed small significant differences between weeks but no clear trend; the within subject weekly variation accounted for less than 3.5% of the total variance for each of the variables. Testing at least four months apart showed a 3.3% fall in the oxygen cost of stepping. No significant diurnal effects on the exercise responses were found. PMID:3433238

  18. Bio-filtration capacity, oxygen consumption and ammonium excretion of Dosinia ponderosa and Chione gnidia (Veneroida: Veneridae) from areas impacted and non-impacted by shrimp aquaculture effluents.

    PubMed

    Ramos-Corella, Karime; Martínez-Córdova, Luis Rafael; Enríquez-Ocaña, Luis Fernando; Miranda-Baeza, Anselmo; López-Elías, José Antonio

    2014-09-01

    Mollusks are some of the most important, abundant and diverse organisms inhabiting not only aquatic ecosystems, but also terrestrial environments. Recently, they have been used for bioremediation of aquaculture effluents; nevertheless, for that purpose it is necessary to analyze the capacity of a particular species. In this context, an experimental investigation was developed to evaluate the performance of two bivalves C. gnidia and D. ponderosa, collected from areas with or without shrimp aquaculture effluents. For this, the filtration capacity (as clearance rate) as well as the oxygen consumption and ammonia excretion rates were measured following standard methods. The clearance rate was significantly higher for D. ponderosa from impacted areas, when com- pared to C. gnidia, from both areas. Contrarily, the oxygen consumption was greater for C. gnidia from impacted areas compared to D. ponderosa from both areas. The same tendency was observed for the ammonia excretion with the highest rates observed for C. gnidia from impacted areas, whereas no differences were observed among D. ponderosa from both areas. The results suggest that both species developed different strategies to thrive and survive under the impacted conditions; D. ponderosa improved its filtration efficiency, while C. gnidia modified its oxygen consumption and ammonia excretion. We concluded that both species, and particularly D. ponderosa, can be used for bioremediation purposes.

  19. Oxygen consumption during cold exposure at 2.1 G in rats adapted to hypergravic fields

    NASA Technical Reports Server (NTRS)

    Horowitz, J.; Patterson, S.; Monson, C.

    1985-01-01

    The thermoregulation ability of rats exposed to various gravitational fields is examined. Male Sprague-Dawley rats were exposed to 22 C and 1 G, and 9 C and 2.1 G in experiment one, 1 G, 2.4 G, 5.8 G and 22 + or - 1.5 C in experiment two, and 1 G, 19-22 C, and 5 C in experiment three. It is observed that the core temperature in the control rats was 36.8 + or 0.4 C at 22C and 30.8 + or - 0.6 C at 9 C, and oxygen consumption dropped from 37 + or - 0.3 C core temperature at 22 C, 36.4 + or - 0.3 C at 9 C, 0.4 oxygen consumption was 8.18 + or - 0.9 ml/min at 22 C, and 14.2 + or - 0.4 ml/min at 9 C. The data from experiment two reveal that tail temperature in the control rats peaked at 2.4 G and at 5.8 G for the acclimated rats, and in experiment three a greater decrease in core temperature is detected in the 2.1-G rats. It is noted that prior acclimation to 2.1 G enhances the thermoregulation ability when exposed to the cold.

  20. Effects of 4-hydroxy-2-nonenal on beef heart mitochondrial ultrastructure, oxygen consumption, and metmyoglobin reduction.

    PubMed

    Ramanathan, R; Mancini, R A; Suman, S P; Cantino, M E

    2012-03-01

    The effects of 4-hydroxy-2-nonenal (HNE) on mitochondria isolated from bovine hearts (n=5) were assessed using ultrastructure, oxygen consumption, membrane permeability, HNE binding, and metmyoglobin reduction in vitro. Pre-incubation (pH 5.6 and 7.4 at 25°C) of mitochondria with HNE decreased oxygen consumption compared with samples without HNE (P<0.05). Electron microscopy revealed that HNE-treated mitochondria were swollen and had increased membrane permeability at pH 7.4, compared with ethanol controls. Conversely, mitochondria incubated with HNE at pH 5.6 had decreased volume and permeability. Fluorescence studies indicate that HNE binds to the membrane of mitochondria isolated from bovine cardiac muscle (at pH 5.6 and 7.4). HNE-treated mitochondria at both pH 5.6 and 7.4 had lower metmyoglobin reduction and NADH dependent metmyoglobin reductase activity compared with control mitochondria without HNE (P<0.05). In addition to covalent binding with myoglobin, HNE may influence beef color stability by interacting with mitochondria.

  1. Oxygen Consumption in the First Stages of Strenuous Work as a Function of Prior Exercise.

    ERIC Educational Resources Information Center

    Gutin, Bernard; And Others

    This study examined the extent to which 10 minutes of prior exercise (PE) at a workload adjusted to maintain a heart rate (HR) of 140 beats per minute could facilitate the mobilization of the oxygen transport system in a strenuous criterion task (CT). The control treatment involved completion of the CT following 10 minutes of rest on the…

  2. Simultaneous Noninvasive Determination of Regional Myocardial Perfusion and Oxygen Content in Rabbits: Toward Direct Measurement of Myocardial Oxygen Consumption at MR Imaging1

    PubMed Central

    Reeder, Scott B.; Holmes, A. Alexander; McVeigh, Elliot R.; Forder, John R.

    2007-01-01

    PURPOSE To determine whether myocardial arterial perfusion and oxygen concentration can be quantified simultaneously from the same images by using spin labeling and the blood oxygenation level-dependent (BOLD) effect with fast spin-echo (SE) imaging. MATERIALS AND METHODS A T2-weighted fast SE pulse sequence was written to image isolated, arrested, blood-perfused rabbit hearts (n = 6) at 4.7 T. Perfusion images with intensity in units of milliliters per minute per gram that covered the entire left ventricle with 0.39 × 0.39 × 3.00-mm resolution were obtained in less than 15 minutes with a 32-fold reduction in imaging time from that of a previous study. Estimates of oxygen concentration were made from the same images acquired for calculation of perfusion images. RESULTS Estimates of regional myocardial oxygen content could be made from the perfusion images; this demonstrated the feasibility of three-dimensional calculation of regional oxygen consumption, which requires concomitant measurement of both oxygen content and flow. Fast SE imaging was shown to bas sensitive to hemoglobin desaturation as standard SE imaging. Perfusion abnormalities and oxygen deficits were easily identified and verified qualitatively with gadopentetate dimeglumine on both perfusion and BOLD images obtained after coronary arterial ligation. CONCLUSION T2-weighted fast SE imaging combined with perfusion-sensitive spin labeling can be used to measure myocardial arterial perfusion and oxygen concentration. This provides the groundwork for calculation of regional myocardial oxygen consumption. PMID:10478241

  3. Dynamic shear-stress-enhanced rates of nutrient consumption in gas-liquid semi-continuous-flow suspensions

    NASA Astrophysics Data System (ADS)

    Belfiore, Laurence A.; Volpato, Fabio Z.; Paulino, Alexandre T.; Belfiore, Carol J.

    2011-12-01

    The primary objective of this investigation is to establish guidelines for generating significant mammalian cell density in suspension bioreactors when stress-sensitive kinetics enhance the rate of nutrient consumption. Ultra-low-frequency dynamic modulations of the impeller (i.e., 35104 Hz) introduce time-dependent oscillatory shear into this transient analysis of cell proliferation under semi-continuous creeping flow conditions. Greater nutrient consumption is predicted when the amplitude A of modulated impeller rotation increases, and stress-kinetic contributions to nutrient consumption rates increase linearly at higher modulation frequency via an application of fluctuation-dissipation response. Interphase mass transfer is required to replace dissolved oxygen as it is consumed by aerobic nutrient consumption in the liquid phase. The theory and predictions described herein could be important at small length scales in the creeping flow regime where viscous shear is significant at the interface between the nutrient medium and isolated cells in suspension. Two-dimensional flow around spherically shaped mammalian cells, suspended in a Newtonian culture medium, is analyzed to calculate the surface-averaged magnitude of the velocity gradient tensor and modify homogeneous rates of nutrient consumption that are stimulated by viscous shear, via the formalism of stress-kinetic reciprocal relations that obey Curie's theorem in non-equilibrium thermodynamics. Time constants for stress-free free and stress-sensitive stress nutrient consumption are defined and quantified to identify the threshold (i.e., stress,threshold) below which the effect of stress cannot be neglected in accurate predictions of bioreactor performance. Parametric studies reveal that the threshold time constant for stress-sensitive nutrient consumption stress,threshold decreases when the time constant for stress

  4. Influence of different production strategies on the stability of color, oxygen consumption and metmyoglobin reducing activity of meat from Ningxia Tan sheep.

    PubMed

    Gao, Xiaoguang; Wang, Zhenyu; Miao, Jing; Xie, Li; Dai, Yan; Li, Xingmin; Chen, Yong; Luo, Hailing; Dai, Ruitong

    2014-02-01

    Fifty male Ningxia Tan sheep were randomly divided into five groups (10 per group). Different feeding strategies were applied to each group for 120 days prior to slaughter. The sheep belong to five groups were pastured for 0 h (feedlot-fed), 2h, 4h, 8h, 12h per day on a natural grazing ground, respectively. M. semitendinosus muscle from Tan sheep was obtained after slaughter. Instrumental color, pH values, oxygen consumption rate, metmyoglobin reducing activity and relative metmyoglobin percentages were analyzed after 1, 3, 5, 7 and 9 days of refrigerated storage. Long-term daily grazing and herbage-based diet were conducive to maintain a lower oxygen consumption rate, higher metmyoglobin reducing activity and lower metmyoglobin accumulation. The combination of pasture-fed and feedlot-fed was conducive to weight gain, and at the same time, increased the color stability of the meat from Ningxia Tan sheep.

  5. Oxygen Consumption by Red Wines. Part II: Differential Effects on Color and Chemical Composition Caused by Oxygen Taken in Different Sulfur Dioxide-Related Oxidation Contexts.

    PubMed

    Carrascon, Vanesa; Fernandez-Zurbano, Purificación; Bueno, Mónica; Ferreira, Vicente

    2015-12-30

    Chemical changes caused by oxidation of red wines during 5 consecutive air-saturation cycles have been assessed. In order to investigate the existing relationship between the effects caused by O2 and the levels and consumption rates of wine SO2, the total oxygen consumed by the wines (16-25 mg/L) was subdivided into different nonmutually exclusive categories. The ones found most influential on chemical changes were the O2 consumed in the first saturation without equivalent SO2 consumption (O2preSO2) and the O2 consumed when levels of free SO2 were below 5 mg/L (radical forming O2). Chromatic changes were strongly related to both O2 categories, even though anthocyanidin degradation was not related to any O2 category. Radical forming O2 prevented both formation of red pigments and reduction of epigallocatechin and other proanthocyanidins, induced accumulation of phenolic acids, and caused losses of β-damascenone and whiskylactone without evidence of acetaldehyde formation. O2preSO2 seemed to play a key role in the formation of blue pigments and in the decrease of Folin index and of many important aroma compounds. PMID:26646423

  6. Per Capita Alcohol Consumption and Suicide Rates in the U.S., 1950-2002

    ERIC Educational Resources Information Center

    Landberg, Jonas

    2009-01-01

    The aim of this paper was to estimate how suicide rates in the United States are affected by changes in per capita consumption during the postwar period. The analysis included Annual suicide rates and per capita alcohol consumption data (total and beverage specific) for the period 1950-2002. Gender- and age-specific models were estimated using the…

  7. Individuals with higher metabolic rates have lower levels of reactive oxygen species in vivo

    PubMed Central

    Salin, Karine; Auer, Sonya K.; Rudolf, Agata M.; Anderson, Graeme J.; Cairns, Andrew G.; Mullen, William; Hartley, Richard C.; Selman, Colin; Metcalfe, Neil B.

    2015-01-01

    There is increasing interest in the effect of energy metabolism on oxidative stress, but much ambiguity over the relationship between the rate of oxygen consumption and the generation of reactive oxygen species (ROS). Production of ROS (such as hydrogen peroxide, H2O2) in the mitochondria is primarily inferred indirectly from measurements in vitro, which may not reflect actual ROS production in living animals. Here, we measured in vivo H2O2 content using the recently developed MitoB probe that becomes concentrated in the mitochondria of living organisms, where it is converted by H2O2 into an alternative form termed MitoP; the ratio of MitoP/MitoB indicates the level of mitochondrial H2O2 in vivo. Using the brown trout Salmo trutta, we tested whether this measurement of in vivo H2O2 content over a 24 h-period was related to interindividual variation in standard metabolic rate (SMR). We showed that the H2O2 content varied up to 26-fold among fish of the same age and under identical environmental conditions and nutritional states. Interindividual variation in H2O2 content was unrelated to mitochondrial density but was significantly associated with SMR: fish with a higher mass-independent SMR had a lower level of H2O2. The mechanism underlying this observed relationship between SMR and in vivo H2O2 content requires further investigation, but may implicate mitochondrial uncoupling which can simultaneously increase SMR but reduce ROS production. To our knowledge, this is the first study in living organisms to show that individuals with higher oxygen consumption rates can actually have lower levels of H2O2. PMID:26382073

  8. Attrition Rate of Oxygen Carriers in Chemical Looping Combustion Systems

    NASA Astrophysics Data System (ADS)

    Feilen, Harry Martin

    This project developed an evaluation methodology for determining, accurately and rapidly, the attrition resistance of oxygen carrier materials used in chemical looping technologies. Existing test protocols, to evaluate attrition resistance of granular materials, are conducted under non-reactive and ambient temperature conditions. They do not accurately reflect the actual behavior under the unique process conditions of chemical looping, including high temperatures and cyclic operation between oxidizing and reducing atmospheres. This project developed a test method and equipment that represented a significant improvement over existing protocols. Experimental results obtained from this project have shown that hematite exhibits different modes of attrition, including both due to mechanical stresses and due to structural changes in the particles due to chemical reaction at high temperature. The test methodology has also proven effective in providing reactivity changes of the material with continued use, a property, which in addition to attrition, determines material life. Consumption/replacement cost due to attrition or loss of reactivity is a critical factor in the economic application of the chemical looping technology. This test method will allow rapid evaluation of a wide range of materials that are best suited for this technology. The most important anticipated public benefit of this project is the acceleration of the development of chemical looping technology for lowering greenhouse gas emissions from fossil fuel combustion.

  9. Investigation of oxygen transfer rates in full scale membrane bioreactors.

    PubMed

    Cornel, P; Wagner, M; Krause, S

    2003-01-01

    In membrane bioreactors (MBRs) for wastewater treatment the secondary clarifier is replaced by a membrane filtration. The advantage of this process is a complete removal of solids from the effluent and a small footprint due to possible high biomass concentrations (MLSS). As oxygen supply counts for more than 70% of total energy cost in municipal WWTPs the design of the aeration system is vital for efficient operation. In this respect the alpha-value is an important influencing factor. The alpha-value depends on the MLSS-concentration as shown in various publications and confirmed by own measurements in two full scale municipal MBRs with MLSS ranging from 7 and 17 kg/m3. Furthermore it must be taken into account that alpha-values are not static values; they vary with loading rates, surfactant concentrations, air flow rates, MLSS concentrations, etc. The average alpha-value at typical 12 kg/m3 MLSS for municipal MBRs is about 0.6 +/- 0.1. As submerged configured MBRs are equipped with an additional coarse bubble "crossflow" aeration system for fouling control, supplementary energy is consumed. Therefore MBRs need more energy compared to conventional treatment plants. Measurements of both aeration systems show that the fine bubble aeration system is more efficient by a factor of three concerning oxygen supply compared to the coarse bubble system.

  10. Is rate–pressure product of any use in the isolated rat heart? Assessing cardiac ‘effort’ and oxygen consumption in the Langendorff‐perfused heart

    PubMed Central

    Aksentijević, Dunja; Lewis, Hannah R.

    2016-01-01

    . Experiments were repeated in the presence of isoprenaline and in unpaced hearts where heart rate was increased by cumulative isoprenaline challenge. In KH buffer‐perfused hearts, MV˙O2 increased with increasing heart rate, but given that left ventricular developed pressure decreased with increases in rate, RPP was not correlated with MV˙O2, lactate production or phosphocreatine/ATP ratio. Although the provision of substrates or β‐adrenoceptor stimulation changed the shape of the RPP–MV˙O2 relationship, neither intervention resulted in a positive correlation between RPP and oxygen consumption. Rate–pressure product is therefore an unreliable index of oxygen consumption or ‘cardiac effort’ in the isolated rat heart. PMID:26585840

  11. Nitrification and its oxygen consumption along the turbid Changjiang River plume

    NASA Astrophysics Data System (ADS)

    Hsiao, S. S.-Y.; Hsu, T.-C.; Liu, J.-W.; Xie, X.; Zhang, Y.; Lin, J.; Wang, H.; Yang, J.-Y. T.; Hsu, S.-C.; Dai, M.; Kao, S.-J.

    2013-05-01

    Nitrification rates of bulk water (NRb) and particle free (NRpf, particle > 3 μm eliminated) were determined along the Changjiang River plume in August 2011 by nitrogen isotope tracer technique. Dissolved oxygen (DO), community respiration rate (CR), nutrients, dissolved organic nitrogen, total suspended matter (TSM), particulate organic carbon/nitrogen (POC/PON), acid-leachable iron and manganese on suspended particles and both archaeal and β-proteobacterial amoA abundance on size-fractioned particle (> 3 μm and 0.22-3 μm) were measured. The NRb ranged from undetectable up to 4.6 μmol L-1 d-1 peaking at salinity of ~ 29. NRb values were positively correlated with ammonia concentration suggesting the importance of substrate in nitrification. In river mouth and inner plume, NRb was much higher than NRpf indicating nitrifying bacteria is mainly particle-associated, which was supported by amoA gene abundance and regression analysis of TSM and NRb. The estimated oxygen demand of nitrification accounted for 0.4% to 317% of CR. The nitrification oxygen demand is much higher than Redfield model's estimation (23%) indicating that oxygen might not be the sole oxidant though DO was sufficient (> 58 μmol kg-1). The excess nitrification oxygen demand showed tendency to occur at lower DO samples accompanying with higher acid-leachable Fe/Mn, which implied reactive Fe3+/Mn4+ may play a role as oxidant in nitrification process. Stoichiometric calculation suggested reactive Fe on particles was even 10-fold the oxidant demand for complete ammonia oxidation along all areas of the plume. The involvement of reactive iron and manganese in nitrification process in oxygenated water further complicated the nitrogen cycling in turbid river plume.

  12. Oxygen uptake in maximal effort constant rate and interval running.

    PubMed

    Pratt, Daniel; O'Brien, Brendan J; Clark, Bradley

    2013-01-01

    This study investigated differences in average VO2 of maximal effort interval running to maximal effort constant rate running at lactate threshold matched for time. The average VO2 and distance covered of 10 recreational male runners (VO2max: 4158 ± 390 mL · min(-1)) were compared between a maximal effort constant-rate run at lactate threshold (CRLT), a maximal effort interval run (INT) consisting of 2 min at VO2max speed with 2 minutes at 50% of VO2 repeated 5 times, and a run at the average speed sustained during the interval run (CR submax). Data are presented as mean and 95% confidence intervals. The average VO2 for INT, 3451 (3269-3633) mL · min(-1), 83% VO2max, was not significantly different to CRLT, 3464 (3285-3643) mL · min(-1), 84% VO2max, but both were significantly higher than CR sub-max, 3464 (3285-3643) mL · min(-1), 76% VO2max. The distance covered was significantly greater in CLRT, 4431 (4202-3731) metres, compared to INT and CR sub-max, 4070 (3831-4309) metres. The novel finding was that a 20-minute maximal effort constant rate run uses similar amounts of oxygen as a 20-minute maximal effort interval run despite the greater distance covered in the maximal effort constant-rate run. PMID:24288501

  13. Effects of nitrous oxide on oxygen consumption by isolated cerebral cortex mitochondria

    SciTech Connect

    Becker, G.L.; Pelligrino, D.A.; Miletich, D.J.; Albrecht, R.F.

    1986-04-01

    The influence of N2O on O2 consumption by mitochondria isolated from the cerebral cortex of goats was examined in incubations preequilibrated with N2O-O2 or N2-O2. Rates of O2 consumption were measured polarographically in a closed system while adenosine triphosphate (ATP) formation was maximal (after addition of excess adenosine diphosphate (ADP), state 3 respiration) and then when it was at zero (after addition of excess oligomycin, state 4 respiration). Compared with 90% N2, 90% N2O produced no change in the rate of state 3 respiration; but an observed 9% decrease in the state 4 rate and an 11% increase in the state 3: state 4 ratio were statistically significant (P less than 0.05). These differences were not seen with N2 and N2O at 70% rather than at 90%, or when succinate rather than pyruvate-malate was used as the respiratory substrate. We conclude the following: Unlike other inhalation anesthetics, N2O at comparable anesthetic concentrations does not inhibit mitochondrial electron transport or ATP formation coupled to it (oxidative phosphorylation). N2O does inhibit one or more other processes, as yet unidentified, which are energetically coupled to electron transport. The increased cerebral O2 consumption that accompanies N2O anesthesia cannot be attributed to a direct effect of N2O on mitochondrial respiration.

  14. A new method to measure local oxygen consumption in human skeletal muscle during dynamic exercise using near-infrared spectroscopy.

    PubMed

    Binzoni, Tiziano; Cooper, Chris E; Wittekind, Anna L; Beneke, Ralph; Elwell, Clare E; Van De Ville, Dimitri; Leung, Terence S

    2010-09-01

    Near infrared spectroscopy (NIRS) can readily report on changes in blood volume and oxygenation. However, it has proved more problematic to measure real-time changes in blood flow and oxygen consumption. Here we report the development of a novel method using NIRS to measure local oxygen consumption in human muscle. The method utilizes the blood volume changes induced by the muscle pump during rhythmically contracting exercising skeletal muscle. We found that the saturation of the blood during the contraction phase was lower than that during the relaxation phase. The calculated oxygen drop was then divided by the contraction time to generate a value for the muscle oxygen consumption in the optical region of interest. As a test we measured the muscle oxygen consumption in the human vastus lateralis during exercise on a cycle ergometer by 11 trained male athletes (32 +/- 11 years old) at 40% and 110% peak aerobic power. We saw an increase from 13.78 micromol 100 g(-1) min(-1) to 19.72 micromol 100 g(-1) min(-1) with the increase in power. The measurements are theoretically exempt from usual NIRS confounders such as myoglobin and adipose tissue and could provide a useful tool for studying human physiology.

  15. The Relationship between Heart Rate Reserve and Oxygen Uptake Reserve in Children and Adolescents

    ERIC Educational Resources Information Center

    Hui, Stanley Sai-chuen; Chan, Janus Wan-sze

    2006-01-01

    The purpose of the present study was to examine the relationship between oxygen uptake (VO[subscript 2]) and heart rate (HR) responses during rest and exercise in Chinese children and youth and to evaluate the relationships between maximal heart rate (%HRmax), heart rate reserve (%HRR), peak oxygen uptake (%VO[subscript 2]peak), and oxygen uptake…

  16. Analysis of beat fluctuations and oxygen consumption in cardiomyocytes by scanning electrochemical microscopy.

    PubMed

    Hirano, Yu; Kodama, Mikie; Shibuya, Masahiro; Maki, Yoshiyuki; Komatsu, Yasuo

    2014-02-15

    The contractile behavior of cardiomyocytes can be monitored by measuring their action potentials, and the analysis is essential for screening the safety of potential drugs. However, immobilizing cardiac cells on a specific electrode is considerably complicated. In this study, we demonstrate that scanning electrochemical microscopy (SECM) can be used to analyze rapid topographic changes in beating cardiomyocytes in a standard culture dish. Various cardiomyocyte contraction parameters and oxygen consumption based on cell respiration could be determined from SECM data. We also confirmed that cellular changes induced by adding the cardiotonic agent digoxin were conveniently monitored by this SECM system. These results show that SECM can be a potentially powerful tool for use in drug development for cardiovascular diseases. PMID:24252541

  17. Decreased Endothelial Nitric Oxide Bioavailability, Impaired Microvascular Function, and Increased Tissue Oxygen Consumption in Children with Falciparum Malaria

    PubMed Central

    Yeo, Tsin W.; Lampah, Daniel A.; Kenangalem, Enny; Tjitra, Emiliana; Weinberg, J. Brice; Granger, Donald L.; Price, Ric N.; Anstey, Nicholas M.

    2014-01-01

    Endothelial nitric oxide (NO) bioavailability, microvascular function, and host oxygen consumption have not been assessed in pediatric malaria. We measured NO-dependent endothelial function by using peripheral artery tonometry to determine the reactive hyperemia index (RHI), and microvascular function and oxygen consumption (VO2) using near infrared resonance spectroscopy in 13 Indonesian children with severe falciparum malaria and 15 with moderately severe falciparum malaria. Compared with 19 controls, children with severe malaria and those with moderately severe malaria had lower RHIs (P = .03); 12% and 8% lower microvascular function, respectively (P = .03); and 29% and 25% higher VO2, respectively. RHIs correlated with microvascular function in all children with malaria (P < .001) and all with severe malaria (P < .001). Children with malaria have decreased endothelial and microvascular function and increased oxygen consumption, likely contributing to the pathogenesis of the disease. PMID:24879801

  18. Effect of 29 days of simulated microgravity on maximal oxygen consumption and fat-free mass of rats

    NASA Technical Reports Server (NTRS)

    Woodman, Christopher R.; Stump, Craig S.; Stump, Jane A.; Rahman, Zia; Tipton, Charles M.

    1991-01-01

    Effects of a 29-days exposure to simulated microgravity on the values of maximal oxygen consumption and fat-free mass (FFM) and on the mechanical efficiency of running were investigated in rats randomly assigned to one of three regimens: head-down suspension (HDS) at 45 deg, horizontal suspension (HS), or cage control (CC). Before suspension and on days 7, 14, 21, and 28, five exercise performance tests were carried out, with measurements related to maximal oxygen consumption, treadmill run time, and mechanical efficiency. It was found that maximal oxygen consumption of both HDS and HS groups decreased significantly at day 7, after which the HDS rats remained decreased while the HS rats returned to presuspension values. Apparent mechanical efficiency in the HDS and HS groups decreased by 22-35 percent during the experimental period, and FFM decreased significantly.

  19. Decreased endothelial nitric oxide bioavailability, impaired microvascular function, and increased tissue oxygen consumption in children with falciparum malaria.

    PubMed

    Yeo, Tsin W; Lampah, Daniel A; Kenangalem, Enny; Tjitra, Emiliana; Weinberg, J Brice; Granger, Donald L; Price, Ric N; Anstey, Nicholas M

    2014-11-15

    Endothelial nitric oxide (NO) bioavailability, microvascular function, and host oxygen consumption have not been assessed in pediatric malaria. We measured NO-dependent endothelial function by using peripheral artery tonometry to determine the reactive hyperemia index (RHI), and microvascular function and oxygen consumption (VO2) using near infrared resonance spectroscopy in 13 Indonesian children with severe falciparum malaria and 15 with moderately severe falciparum malaria. Compared with 19 controls, children with severe malaria and those with moderately severe malaria had lower RHIs (P = .03); 12% and 8% lower microvascular function, respectively (P = .03); and 29% and 25% higher VO2, respectively. RHIs correlated with microvascular function in all children with malaria (P < .001) and all with severe malaria (P < .001). Children with malaria have decreased endothelial and microvascular function and increased oxygen consumption, likely contributing to the pathogenesis of the disease.

  20. Kinetic studies of lipid oxidation induced by hemoglobin measured by consumption of dissolved oxygen in a liposome model system.

    PubMed

    Carvajal, Ana Karina; Rustad, Turid; Mozuraityte, Revilija; Storrø, Ivar

    2009-09-01

    The effect of hemoglobin (Hb) and lipid concentration, pH, temperature, and different antioxidants on heme-mediated lipid oxidation of liposomes from marine phospholipids was studied. The rate of lipid oxidation was measured by consumption of dissolved oxygen. Heme-mediated lipid oxidation at different Hb and lipid concentrations was modeled by Michaelis-Menten kinetics. The maximum rate (V(max)) for the reaction with cod and bovine Hb as a pro-oxidant was 66.2 +/- 3.4 and 56.6 +/- 3.4 microM/min, respectively. The Michaelis-Menten constant (K(m)) for the reaction with cod and bovine Hb was 0.67 +/- 0.09 and 1.2 +/- 0.2 microM, respectively. V(max) for the relationship between the oxygen uptake rate and lipid concentration was 43.2 +/- 1.5 microM/min, while the K(m) was 0.93 +/- 0.14 mg/mL. The effect of the temperature followed Arrhenius kinetics, and there was no significant difference in activation energy between cod and bovine Hb. The rate of lipid oxidation induced by bovine Hb was highest around pH 6. Ethylenediaminetetraacetic acid (EDTA) had no significant effect on heme-mediated lipid oxidation, but alpha-tocopherol and astaxanthin worked well as antioxidants. Kinetic differences were found between iron and Hb as pro-oxidants, and the efficacy of the antioxidants depended upon the pro-oxidant in the system. PMID:19691337

  1. Effects of metal contamination in situ on osmoregulation and oxygen consumption in the mudflat fiddler crab Uca rapax (Ocypodidae, Brachyura).

    PubMed

    Capparelli, Mariana V; Abessa, Denis M; McNamara, John C

    2016-01-01

    The contamination of estuaries by metals can impose additional stresses on estuarine species, which may exhibit a limited capability to adjust their regulatory processes and maintain physiological homeostasis. The mudflat fiddler crab Uca rapax is a typical estuarine crab, abundant in both pristine and contaminated areas along the Atlantic coast of Brazil. This study evaluates osmotic and ionic regulatory ability and gill Na(+)/K(+)-ATPase activity in different salinities (<0.5, 25 and 60‰ S) and oxygen consumption rates at different temperatures (15, 25 and 35°C) in U. rapax collected from localities along the coast of São Paulo State showing different histories of metal contamination (most contaminated Ilha Diana, Santos>Rio Itapanhaú, Bertioga>Picinguaba, Ubatuba [pristine reference site]). Our findings show that the contamination of U. rapax by metals in situ leads to bioaccumulation and induces biochemical and physiological changes compared to crabs from the pristine locality. U. rapax from the contaminated sites exhibit stronger hyper- and hypo-osmotic regulatory abilities and show greater gill Na(+)/K(+)-ATPase activities than crabs from the pristine site, revealing that the underlying biochemical machinery can maintain systemic physiological processes functioning well. However, oxygen consumption, particularly at elevated temperatures, decreases in crabs showing high bioaccumulation titers but increases in crabs with low/moderate bioaccumulation levels. These data show that U. rapax chronically contaminated in situ exhibits compensatory biochemical and physiological adjustments, and reveal the importance of studies on organisms exposed to metals in situ, particularly estuarine invertebrates subject to frequent changes in natural environmental parameters like salinity and temperature.

  2. Production of free radicals and oxygen consumption by primary equine endothelial cells during anoxia-reoxygenation.

    PubMed

    de Rebière de Pouyade, Geoffroy; Salciccia, Alexandra; Ceusters, Justine; Deby-Dupont, Ginette; Serteyn, Didier; Mouithys-Mickalad, Ange

    2011-01-01

    The endothelium plays an active role in ischemia/reperfusion injuries. Herein, we report the effect of a single or successive cycles of anoxia/reoxygenation (A/R) on the mitochondrial respiratory function of equine endothelial cells (cultured from carotids) monitored by high resolution oxymetry, and on their production of reactive oxygen species (ROS). ROS were measured by electron paramagnetic resonance (ESR) using POBN and DMPO spin traps, and by gas chromatography (GC) of ethylene released by ROS-induced α-keto-γ-(methylthio)butyric acid (KMB) oxidation. The oxygen consumption significantly decreased with the number of A/R cycles, and POBN-ESR spectra were specific of adducts formed in the cells from superoxide anion. After a one-hour A/R cycle, high intensity DMPO-ESR spectra were observed and assigned to superoxide anion trapping; the GC results confirmed an important production of ROS compared to normoxic cells. These results show that A/R induces mitochondrial alterations in endothelial cells, and strongly stimulates their oxidative activity as demonstrated by ESR and GC methods. PMID:22207886

  3. Pedaling rate is an important determinant of human oxygen uptake during exercise on the cycle ergometer

    PubMed Central

    Formenti, Federico; Minetti, Alberto E; Borrani, Fabio

    2015-01-01

    Estimation of human oxygen uptake () during exercise is often used as an alternative when its direct measurement is not feasible. The American College of Sports Medicine (ACSM) suggests estimating human during exercise on a cycle ergometer through an equation that considers individual's body mass and external work rate, but not pedaling rate (PR). We hypothesized that including PR in the ACSM equation would improve its prediction accuracy. Ten healthy male participants’ (age 19–48 years) were recruited and their steady-state was recorded on a cycle ergometer for 16 combinations of external work rates (0, 50, 100, and 150 W) and PR (50, 70, 90, and 110 revolutions per minute). was calculated by means of a new equation, and by the ACSM equation for comparison. Kinematic data were collected by means of an infrared 3-D motion analysis system in order to explore the mechanical determinants of . Including PR in the ACSM equation improved the accuracy for prediction of sub-maximal during exercise (mean bias 1.9 vs. 3.3 mL O2 kg−1 min−1) but it did not affect the accuracy for prediction of maximal (P > 0.05). Confirming the validity of this new equation, the results were replicated for data reported in the literature in 51 participants. We conclude that PR is an important determinant of human during cycling exercise, and it should be considered when predicting oxygen consumption. PMID:26371230

  4. Failure of phenoxybenzamine and pimozide to diminish changes in oxygen consumption and body temperature produced by caffeine.

    PubMed

    Estler, C J

    1979-06-01

    The effects of a dopamine antagonist (pimozide) and an alpha-adrenergic receptor blocking agent (phenoxybenzamine) on caffeine-induced changes in oxygen consumption. body temperature, blood glucose and non-esterified fatty acids (NEFA) were studied in mice. Both drugs had no effect on the increase of the oxygen consumption produced by caffeine. The decline of the body temperature induced by caffeine was not significantly influenced by pimozide, while phenoxybenzamine accentuated the hypothermic effect of caffeine. The results indicate that alpha-adrenergic and dopamine receptors do not play an essential role in the caffeine-induced stimulation of overall metabolism and hypothermia. PMID:485730

  5. Oxygen impacts on dipolarization fronts and reconnection rate

    NASA Astrophysics Data System (ADS)

    Liang, Haoming; Ashour-Abdalla, Maha; Lapenta, Giovanni; Walker, Raymond J.

    2016-02-01

    Spacecraft observations near a magnetotail X line show that oxygen (O+) ions are minor species during nonstorm substorms, but they can become major species during some of the storm time substorms. Dipolarization fronts (DFs), which are characterized by a sharp increase northward magnetic field in the magnetotail, are commonly observed during magnetospheric substorms. In this study, we investigated the O+ effects on DFs and the reconnection rate during magnetotail reconnection. We used a 2.5-D implicit particle-in-cell simulation in a 2-D Harris current sheet in the presence of H+ and O+ ions. Simulation runs with equal number densities of O+ and H+ (O+ run) and with pure H+ ion species (H+ run) were performed. Comparing the two different runs, we found that both the reconnection rate and the DF speed in the O+ run were much less than those in the H+ run. By studying the force balance and plasma composition at the DF, we found that the outflow magnetic flux and DF propagation were encumbered by the current sheet O+ inertia, which reduced the DF speed and delayed the reconnection rate in the O+ run. We also found an ambipolar electric field in the O+ run due to the different inflow and outflow speeds of O+ and electrons in the O+ diffusion region. As a result, this ambipolar electric field induced O+ drag on the convective magnetic field in the O+ diffusion region. The small reconnection rate determined in the O+ run can be attributed to the current sheet inertia and the O+ drag on the convective magnetic flux.

  6. The response to monochromatic light flashes of the oxygen consumption of honeybee drone photoreceptors.

    PubMed

    Jones, G J; Tsacopoulos, M

    1987-05-01

    Local measurements of the fall in oxygen pressure on stimulation of slices of the retina of the honeybee drone by flashes of light were made with oxygen microelectrodes and used to calculate the kinetics of the extra oxygen consumption (delta QO2) induced by each flash. The action spectrum for delta QO2 was obtained from response-intensity curves in response to brief (40 ms) monochromatic light flashes. The action spectrum of receptor potentials was obtained with the same experimental conditions. The two action spectra match closely: they deviate slightly from the photosensitivity spectrum of the drone rhodopsin (R). The deviation is thought to be due to wavelength-dependent light scattering and absorption in the preparation. In these experiments, the visual pigment was first illuminated with orange light, which is known to convert the bistable drone photopigment predominantly to the R state from the metarhodopsin (M) state. When long (300-900 ms) light flashes were used to elicit delta QO2, the responses to different wavelengths could not be matched in time course (as for the short flashes). Flashes producing large R-to-M conversions produced a prolonged delta QO2. The prolongation did not occur after double flashes, which produced both large R-to-M and M-to-R conversions. Similar changes in the length of afterpotentials in the photoreceptor cells and in a long-lasting decrease in photoreceptor intracellular K+ activity were found after long single or double flashes. The results are interpreted to show that the initial event for stimulation by light of metabolism in the drone retina is the same as that for stimulation of electrical responses (i.e., absorption of photons by R). Absorption of photons by M can produce an inhibitory effect on this stimulation.

  7. [The value of systematic monitoring of oxygen consumption in the diagnosis and therapy of septic shock].

    PubMed

    Pilas, V; Cubrilo, M; Bakula, V; Vranjkovic, S; Bakula, B; Bilic, A

    1990-01-01

    In 31 patients with sepsis and multiple organic dysfunction, changes in the systemic oxygen consumption (VO2) during reanimation were observed in order to discover more objective indicators of the course and prognosis of the disease. In a prospective randomized study, 21 live (Group 1) and 11 dead patients (Group 2) were included. The investigation was based upon the application of the invasive tracing of oxygen hemodynamics and transport. The findings of the initially hypovolemic status were compared with those of the stabile normovolemic status obtained by the application of infusions and the blood volume substitute. In the early phase of the disease there were no significant differences in the clinical finding of the circulatory shock and the volume deficit of the circulated blood between these two groups of patients. Group 1 patients had lower values of the cardiac index (CI) and the systemic oxygen transport (DO2). In them there was a greater frequency of acute organic insufficiency, especially pulmonal, renal and hepatal. In the initial status VO2 decreased. In the normovolemic status of Group 1, a significant VO2 was found, while in Group 2 in spite of a DO2 increase and hemodynamics improvement, a more significant VO2 increase was not obtained. As VO2 is an objective indicator of oxidative metabolic reactions of the organism and the circulatory system, the authors maintain that by the VO2 tracing, a better insight into the seriousness and course of the disease is obtained, and that an inadequate VO2 finding during the therapeutic treatment requires a revision of the treatment. PMID:2077821

  8. Influence of oxygen transfer on Pseudomonas putida effects on growth rate and biodesulfurization capacity.

    PubMed

    Escobar, S; Rodriguez, A; Gomez, E; Alcon, A; Santos, V E; Garcia-Ochoa, Felix

    2016-04-01

    The growth rate and desulfurization capacity accumulated by the cells during the growth of Pseudomonas putida KTH2 under different oxygen transfer conditions in a stirred and sparged tank bioreactor have been studied. Hydrodynamic conditions were changed using different agitation conditions. During the culture, several magnitudes associated to growth, such as the specific growth rate, the dissolved oxygen concentration and the carbon source consumption have been measured. Experimental results indicate that cultures are influenced by the fluid dynamic conditions into the bioreactor. An increase in the stirrer speed from 400 to 700 rpm has a positive influence on the cell growth rate. Nevertheless, the increase of agitation from 700 to 2000 rpm hardly has any influence on the growth rate. The effect of fluid dynamics on the cells development of the biodesulfurization (BDS) capacity of the cells during growth is different. The activities of the intracellular enzymes involved in the 4S pathway change with dissolved oxygen concentration. The enzyme activities have been evaluated in cells at several growth time and different hydrodynamic conditions. An increase of the agitation from 100 to 300 rpm has a positive influence on the development of the overall BDS capacity of the cells during growth. This capacity shows a decrease for higher stirrer speeds and the activity of the enzymes monooxygenases DszC and DszA decreases dramatically. The highest value of the activity of DszB enzyme was obtained with cells cultured at 100 rpm, while this activity decreases when the stirrer speed was increased higher than this value. PMID:26762940

  9. Biomass burning fuel consumption rates: a field measurement database

    NASA Astrophysics Data System (ADS)

    van Leeuwen, T. T.; van der Werf, G. R.; Hoffmann, A. A.; Detmers, R. G.; Rücker, G.; French, N. H. F.; Archibald, S.; Carvalho, J. A., Jr.; Cook, G. D.; de Groot, W. J.; Hély, C.; Kasischke, E. S.; Kloster, S.; McCarty, J. L.; Pettinari, M. L.; Savadogo, P.; Alvarado, E. C.; Boschetti, L.; Manuri, S.; Meyer, C. P.; Siegert, F.; Trollope, L. A.; Trollope, W. S. W.

    2014-12-01

    Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. Fuel consumption (FC) depends on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC is usually modeled or taken selectively from the literature. We compiled the peer-reviewed literature on FC for various biomes and fuel categories to understand FC and its variability better, and to provide a database that can be used to constrain biogeochemical models with fire modules. We compiled in total 77 studies covering 11 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha-1 with a standard deviation of 2.2), tropical forest (n = 19, FC = 126 ± 77), temperate forest (n = 12, FC = 58 ± 72), boreal forest (n = 16, FC = 35 ± 24), pasture (n = 4, FC = 28 ± 9.3), shifting cultivation (n = 2, FC = 23, with a range of 4.0-43), crop residue (n = 4, FC = 6.5 ± 9.0), chaparral (n = 3, FC = 27 ± 19), tropical peatland (n = 4, FC = 314 ± 196), boreal peatland (n = 2, FC = 42 [42-43]), and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e.g. only three measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences in FC were found within the defined biomes: for example, FC of temperate pine forests in the USA was 37% lower than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC, not only between biomes but also within biomes and fuel classes. This implies that substantial uncertainties are associated with using biome-averaged values to represent FC for whole

  10. In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care.

    PubMed

    Ciaffoni, Luca; O'Neill, David P; Couper, John H; Ritchie, Grant A D; Hancock, Gus; Robbins, Peter A

    2016-08-01

    There are no satisfactory methods for monitoring oxygen consumption in critical care. To address this, we adapted laser absorption spectroscopy to provide measurements of O2, CO2, and water vapor within the airway every 10 ms. The analyzer is integrated within a novel respiratory flow meter that is an order of magnitude more precise than other flow meters. Such precision, coupled with the accurate alignment of gas concentrations with respiratory flow, makes possible the determination of O2 consumption by direct integration over time of the product of O2 concentration and flow. The precision is illustrated by integrating the balance gas (N2 plus Ar) flow and showing that this exchange was near zero. Measured O2 consumption changed by <5% between air and O2 breathing. Clinical capability was illustrated by recording O2 consumption during an aortic aneurysm repair. This device now makes easy, accurate, and noninvasive measurement of O2 consumption for intubated patients in critical care possible.

  11. Nitrification and its oxygen consumption along the turbid Chang Jiang River plume

    NASA Astrophysics Data System (ADS)

    Hsiao, S. S.-Y.; Hsu, T.-C.; Liu, J.-w.; Xie, X.; Zhang, Y.; Lin, J.; Wang, H.; Yang, J.-Y. T.; Hsu, S.-C.; Dai, M.; Kao, S.-J.

    2014-04-01

    Nitrification is a series of processes that oxidizes ammonia to nitrate, which contributes to hypoxia development in coastal oceans, especially in eutrophicated regions. The nitrification rate of bulk water (NRb) and particle free water (NRpf, particle > 3 μm eliminated) were determined along the Chang Jiang River plume in August 2011 by nitrogen isotope tracer technique. Measurements of dissolved oxygen (DO), community respiration rate (CR), nutrients, dissolved organic nitrogen (DON), total suspended matter (TSM), particulate organic carbon/nitrogen (POC / PON), acid-leachable iron and manganese on suspended particles and both archaeal and β-proteobacterial ammonia monooxygenase subunit A gene (amoA) abundance on size-fractioned particles (> 3 μm and 0.22-3 μm) were conducted. The NRb ranged from undetectable up to 4.6 μmol L-1 day-1, peaking at a salinity of ~ 29. NRb values were positively correlated with ammonium concentration, suggesting the importance of substrate in nitrification. In the river mouth and the inner plume, NRb was much higher than NRpf, indicating that the nitrifying microorganism is mainly particle associated, which was supported by its significant correlation with amoA gene abundance and TSM concentration. The estimated oxygen demands of nitrification accounted for 0.32 to 318% of CR, in which 50% samples demanded more oxygen than that predicted by by the Redfield model (23%), indicating that oxygen might not be the sole oxidant though DO was sufficient (> 58 μmol kg-1) throughout the observation period. The excess nitrification-associated oxygen demand (NOD) showed a tendency to occur at lower DO samples accompanied by higher acid-leachable Fe / Mn, which implied reactive Fe3+ / Mn4+ may play a role as oxidant in the nitrification process. Stoichiometric calculation suggested that reactive Fe on particles was 10 times the oxidant demand required to complete ammonia oxidation in the entire plume. The potential involvement of reactive

  12. Decrease in the etch rate of polymers in the oxygen afterglow with increasing gas flow rate

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Wydeven, T.

    1988-01-01

    This paper reports the variation of the etch rate of polymers in the afterglow of a radio frequency discharge in oxygen as a function of total flow rate in the range 2-10 cu cm (STP)/min. The measurements were made at ambient temperature with the O(P-3) concentration held essentially constant. Results are reported on three polymers: cis-polybutadiene, a polybutadiene with 33 percent 1,2 double bonds, and a polybutadiene with 40 percent 1,2 double bonds. It has been observed that the etch rate of these polymers decreases significantly with increasing flow rate, strongly suggesting that the vapor-phase products of polymer degradation contribute to the degradation process.

  13. A method for measuring the oxygen consumption of photoreceptor cells in the steady state and after a brief stimulation by light.

    PubMed

    Poitry, S; Tsacopoulos, M; Widmer, H

    1990-01-01

    The rate of oxygen consumption (QO2) in living tissue cannot be directly measured but may be estimated by mathematically modelling the diffusion of oxygen in the tissue and measuring the local partial pressure of oxygen (PO2). The retina of arthropods contains only two types of cells, photoreceptor and glial cells, which are regularly distributed. Because of this simple structure, simple models of diffusion can be used to estimate the QO2 of the tissue, both in steady state and after a brief stimulation by light. We used a model of diffusion in a plane sheet to calculate the QO2 in a slice of honeybee drone retina, which contains a few thousand cells. We then modified the method slightly and used a model with spherical symmetry to calculate the QO2 in the cluster of three photoreceptor cells of the barnacle and in the single ventral photoreceptor cells of Limulus.

  14. Synchronous temperature rate control for refrigeration with reduced energy consumption

    SciTech Connect

    Gomes, Alberto Regio; Keres, Stephen L.; Kuehl, Steven J.; Litch, Andrew D.; Richmond, Peter J.; Wu, Guolian

    2015-09-22

    Methods of operation for refrigerator appliance configurations with a controller, a condenser, at least one evaporator, a compressor, and two refrigeration compartments. The configuration may be equipped with a variable-speed or variable-capacity compressor, variable speed evaporator or compartment fans, a damper, and/or a dual-temperature evaporator with a valve system to control flow of refrigerant through one or more pressure reduction devices. The methods may include synchronizing alternating cycles of cooling each compartment to a temperature approximately equal to the compartment set point temperature by operation of the compressor, fans, damper and/or valve system. The methods may also include controlling the cooling rate in one or both compartments. Refrigeration compartment cooling may begin at an interval before or after when the freezer compartment reaches its lower threshold temperature. Freezer compartment cooling may begin at an interval before or after when the freezer compartment reaches its upper threshold temperature.

  15. Effect of the Combination of Ezetimibe and Simvastatin on Gluconeogenesis and Oxygen Consumption in the Rat Liver.

    PubMed

    Bracht, Lívia; Caparroz-Assef, Silvana Martins; Bracht, Adelar; Bersani-Amado, Ciomar Aparecida

    2016-06-01

    The aim of this work was to investigate the effects of chronic treatment with the combination of ezetimibe and simvastatin on gluconeogenesis in rat liver. Rats were treated daily for 28 days with the combination of ezetimibe and simvastatin (10/40 mg/kg) by oral gavage. To measure gluconeogenesis and the associated pathways, isolated perfused rat liver was used. In addition, subcellular fractions, such as microsomes and mitochondria, were used for complementary measures of enzymatic activities. Treatment with the combination of simvastatin and ezetimibe resulted in a decrease in gluconeogenesis from pyruvate (-62%). Basal oxygen consumption of the treated animals was higher (+22%) than that of the control rats, but the resulting oxygen consumption that occurred after pyruvate infusion was 43% lower in animals treated with the combination of simvastatin and ezetimibe. Oxygen consumption in the livers from treated animals was completely inhibited by cyanide (electron transport chain inhibitor), but not by proadifen (cytochrome P450 inhibitor). Chronic treatment with ezetimibe/simvastatin decreased the activity of the key enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase by 59% and 45%, respectively, which is probably the major reason for the decreased gluconeogenesis seen in ezetimibe-/simvastatin-treated rats. It is also possible that part of the effect of this combination on gluconeogenesis and on the oxygen consumption is related to the impairment of mitochondrial energy transduction. PMID:26552039

  16. [Metabolic response in the acute stage of cerebral infarction--with special reference to oxygen consumption and resting metabolic expenditure].

    PubMed

    Touho, H; Sawada, T; Karasawa, J; Kikuchi, H; Ohgitani, S

    1986-05-01

    Oxygen consumption, carbon dioxide production, respiratory quotients, and resting metabolic expenditure were measured in 23 patients with cerebral infarction in their acute stage. Metabolic measurement were carried out with the technique of indirect calorimetry on their admission within two days from the onsets. At the same time, urine was collected twenty-four hours to measure urinary catecholamine excretion. Mean value of resting metabolic expenditure was 115.1% and this positively correlated with urinary catecholamine, especially noradrenaline excretion. Maximum value of resting metabolic expenditure was up to 187.1% of that expected for an uninjured resting person of equivalent age, sex, and body surface area. Oxygen consumption and carbon dioxide production also positively correlated to urinary catecholamine excretion. On the other hand, respiratory quotients did not have any significant correlation with oxygen consumption, carbon dioxide production, resting metabolic expenditure, or urinary catecholamine excretion. From those facts, it was implied that overactivity of sympathetic nervous system existed in their acute stage of cerebral infarction, and the overflow might directly influence oxygen consumption, carbon dioxide production, and resting metabolic expenditure, and moreover we had to take into consideration of hyper-metabolic state to manage patients with ischemic cerebrovascular diseases as malnutrition might cause weight loss and immune incompetence.

  17. Leucine modulation of mitochondrial mass and oxygen consumption in skeletal muscle cells and adipocytes

    PubMed Central

    Sun, Xiaocun; Zemel, Michael B

    2009-01-01

    Background The effects of dairy on energy metabolism appear to be mediated, in part, by leucine and calcium which regulate both adipocyte and skeletal muscle energy metabolism. We recently demonstrated that leucine and calcitriol regulate fatty acid oxidation in skeletal muscle cells in vitro, with leucine promoting and calcitriol suppressing fatty acid oxidation. Moreover, leucine coordinately regulated adipocyte lipid metabolism to promote flux of lipid to skeletal muscle and regulate metabolic flexibility. We have now investigated the role of mitochondrial biogenesis in mediating these effects. Methods We tested the effect of leucine, calcitriol and calcium in regulation of mitochondrial mass using a fluorescence method and tested mitochondrial biogenesis regulatory genes as well mitochondrial component genes using real-time PCR. We also evaluated the effect of leucine on oxygen consumption with a modified perfusion system. Results Leucine (0.5 mM) increased mitochondrial mass by 30% and 53% in C2C12 myocytes and 3T3-L1 adipocytes, respectively, while calcitriol (10 nM) decreased mitochondrial abundance by 37% and 27% (p < 0.02). Leucine also stimulated mitochondrial biogenesis genes SIRT-1, PGC-1α and NRF-1 as well as mitochondrial component genes UCP3, COX, and NADH expression by 3–5 fold in C2C12 cells (p < 0.003). Adipocyte-conditioned medium reduced mitochondrial abundance (p < 0.001) and decreased UCP3 but increased PGC-1α expression in myocytes, suggesting a feedback stimulation of mitochondrial biogenesis. Similar data were observed in C2C12 myocytes co-cultured with adipocytes, with co-culture markedly suppressing mitochondrial abundance (p < 0.02). Leucine stimulated oxygen consumption in both C2C12 cells and adipocytes compared with either control or valine-treated cells. Transfection of C2C12 myocytes with SIRT-1 siRNA resulted in parallel suppression of SIRT-1 expression and leucine-induced stimulation of PGC-1α and NRF-1, indicating that SIRT

  18. Effects of oxygen and catalyst on tetraphenylborate decomposition rate

    SciTech Connect

    Walker, D.D.

    1999-12-15

    Previous studies indicate that palladium catalyzes rapid decomposition of alkaline tetraphenylborate slurries. Oxygen inhibits the reaction at low temperature (25 C), presumably by preventing activation of the catalyst. The present study investigated oxygen's inhibiting effectiveness at higher temperature (45 C) and catalyst concentrations.

  19. Reduction in Post-Marathon Peak Oxygen Consumption: Sign of Cardiac Fatigue in Amateur Runners?

    PubMed Central

    Sierra, Ana Paula Rennó; da Silveira, Anderson Donelli; Francisco, Ricardo Contesini; Barretto, Rodrigo Bellios de Mattos; Sierra, Carlos Anibal; Meneghelo, Romeu Sergio; Kiss, Maria Augusta Peduti Dal Molin; Ghorayeb, Nabil; Stein, Ricardo

    2016-01-01

    Background Prolonged aerobic exercise, such as running a marathon, produces supraphysiological stress that can affect the athlete's homeostasis. Some degree of transient myocardial dysfunction ("cardiac fatigue") can be observed for several days after the race. Objective To verify if there are changes in the cardiopulmonary capacity, and cardiac inotropy and lusitropy in amateur marathoners after running a marathon. Methods The sample comprised 6 male amateur runners. All of them underwent cardiopulmonary exercise testing (CPET) one week before the São Paulo Marathon, and 3 to 4 days after that race. They underwent echocardiography 24 hours prior to and immediately after the marathon. All subjects were instructed not to exercise, to maintain their regular diet, ingest the same usual amount of liquids, and rest at least 8 hours a day in the period preceding the CPET. Results The athletes completed the marathon in 221.5 (207; 250) minutes. In the post-marathon CPET, there was a significant reduction in peak oxygen consumption and peak oxygen pulse compared to the results obtained before the race (50.75 and 46.35 mL.kg-1 .min-1; 19.4 and 18.1 mL.btm, respectively). The echocardiography showed a significant reduction in the s' wave (inotropic marker), but no significant change in the E/e' ratio (lusitropic marker). Conclusions In amateur runners, the marathon seems to promote changes in the cardiopulmonary capacity identified within 4 days after the race, with a reduction in the cardiac contractility. Such changes suggest that some degree of "cardiac fatigue" can occur. PMID:26760783

  20. A comparison of the shuttle and 6 minute walking tests with measured peak oxygen consumption in patients with heart failure.

    PubMed

    Green, D J; Watts, K; Rankin, S; Wong, P; O'Driscoll, J G

    2001-09-01

    This study investigated the use of an incremental, externally-paced 10 m shuttle walk test (SWT) as an objective, reliable and predictive test of functional capacity in patients with heart failure (CHF). The SWT was compared to a 6 minute walk test (6WT) and a maximal symptom-limited treadmill peak oxygen consumption (VO2peak) test. Experiment 1 examined the reproducibility of the SWT. Two SWF trials were performed and distance ambulated (DA), heart rate (HR) and rate of perceived exertion (RPE) results compared. In experiment 2, SWT, 6WT, and VO2 peak tests were performed and HR. RPE and ambulatory VO2 compared. The SWT demonstrated strong test/retest reliability for DA (r = 0.98). HR (r = 0.96) and RPE (r = 0.89). Treadmill VO2 peak was significantly correlated with DA during the SWT (r = 0.83, P < 0.05), but not the 6WT. SWT peak VO2 (18.5 +/- 1.8 ml.kg(-1) x min(-1)) and treadmill VO2 peak (18.3 +/-2.0 ml.kg(-1) x min(-1)) were also highly correlated (r = 0.78, P < 0.05). Conversely, 6WT peak VO2 and treadmill VO2 peak were not significantly correlated. This study suggests the SWT is a reliable, objective test, highly predictive of VO2 peak which may be a more optimal field exercise test than the self paced 6WT.

  1. Feline left ventricular oxygen consumption is not affected by volume expansion, ejection or redevelopment of pressure during relaxation.

    PubMed

    Duwel, C M; Westerhof, N

    1988-09-01

    We studied the dependency of myocardial oxygen consumption on the mechanical events during left ventricular relaxation in isolated supported cat hearts. The volume of the left ventricle was controlled by means of a balloon connected to a membrane pump. Oxygen consumption (MVO2 in cm3.min-1.100 g-1) for three protocols (PROT) performed at peak isovolumic pressure, was studied: (1) rapid ejection to zero pressure, (2) partial rapid ejection followed by redevelopment of pressure, (3) volume expansion during relaxation, and compared with oxygen consumption of isovolumic (ISOV) beats. We found (mean +/- SD): (table; see text) In the protocols 1 and 3 the differences were not significant (paired Student's t-test, p greater than 0.05). In protocols 1 and 2 left ventricular volume was decreased up to 2.15 cm3 (i.e. stroke volume, SV) during the pressure release. We studied the specific effect of ejection (i.e., wall muscle shortening) in a fourth protocol in which the ventricle ejected up to 2.7 cm3 under nearly zero pressure load (isobaric contraction). There was a small amount of oxygen consumption associable with this unloaded ejection i.e. MVO2 = 3.38 (+/- 0.47) + 0.30 (+/- 0.16) SV, but it was too small to compensate for a decrease in MVO2 expected from the pressure release according to the tension time index. These findings suggest that oxygen consumption does not depend on the mechanical events during ventricular relaxation. PMID:3174398

  2. [Design of Oxygen Saturation, Heart Rate, Respiration Rate Detection System Based on Smartphone of Android Operating System].

    PubMed

    Zhu, Mingshan; Zeng, Bixin

    2015-03-01

    In this paper, we designed an oxygen saturation, heart rate, respiration rate monitoring system based on smartphone of android operating system, physiological signal acquired by MSP430 microcontroller and transmitted by Bluetooth module. PMID:26524782

  3. [Design of Oxygen Saturation, Heart Rate, Respiration Rate Detection System Based on Smartphone of Android Operating System].

    PubMed

    Zhu, Mingshan; Zeng, Bixin

    2015-03-01

    In this paper, we designed an oxygen saturation, heart rate, respiration rate monitoring system based on smartphone of android operating system, physiological signal acquired by MSP430 microcontroller and transmitted by Bluetooth module.

  4. Sulfur Isotope Trends in Archean Microbialite Facies Record Early Oxygen Production and Consumption

    NASA Astrophysics Data System (ADS)

    Zerkle, A.; Meyer, N.; Izon, G.; Poulton, S.; Farquhar, J.; Claire, M.

    2014-12-01

    The major and minor sulfur isotope composition (δ34S and Δ33S) of pyrites preserved in ~2.65-2.5 billion-year-old (Ga) microbialites record localized oxygen production and consumption near the mat surface. These trends are preserved in two separate drill cores (GKF01 and BH1-Sacha) transecting the Campbellrand-Malmani carbonate platform (Ghaap Group, Transvaal Supergroup, South Africa; Zerkle et al., 2012; Izon et al., in review). Microbialite pyrites possess positive Δ33S values, plotting parallel to typical Archean trends (with a Δ33S/δ34S slope of ~0.9) but enriched in 34S by ~3 to 7‰. We propose that these 34S-enriched pyrites were formed from a residual pool of sulfide that was partially oxidized via molecular oxygen produced by surface mat-dwelling cyanobacteria. Sulfide, carrying the range of Archean Δ33S values, could have been produced deeper within the microbial mat by the reduction of sulfate and elemental sulfur, then fractionated upon reaction with O2 produced by oxygenic photosynthesis. Preservation of this positive 34S offset requires that: 1) sulfide was only partially (50­­-80%) consumed by oxidation, meaning H2S was locally more abundant (or more rapidly produced) than O2, and 2) the majority of the sulfate produced via oxidation was not immediately reduced to sulfide, implying either that the sulfate pool was much larger than the sulfide pool, or that the sulfate formed near the mat surface was transported and reduced in another part of the system. Contrastingly, older microbialite facies (> 2.7 Ga; Thomazo et al., 2013) appear to lack these observed 34S enrichments. Consequently, the onset of 34S enrichments could mark a shift in mat ecology, from communities dominated by anoxygenic photosynthesizers to cyanobacteria. Here, we test these hypotheses with new spatially resolved mm-scale trends in sulfur isotope measurements from pyritized stromatolites of the Vryburg Formation, sampled in the lower part of the BH1-Sacha core. Millimeter

  5. Drag reducing chemical enables increased sea water injection without increasing the oxygen corrosion rate

    SciTech Connect

    McMahon, A.J.; Smith, P.S.; Lee, Y.

    1997-08-01

    Water soluble drag reducer chemicals have enabled significant increases in flow rates in many oilfield water injection systems. In some cases there is concern that this could lead to increased oxygen corrosion whenever the dissolved oxygen concentration strays above a typical injection target such as 20 ppb O{sub 2}. The effect of a chemical drag reducer on oxygen corrosion of carbon steel was examined in a large scale flow loop simulating a sea water injection line. Drag reduction (up to 48%) matched corrosion reduction (up to 39%). This means that drag reducer has a self compensating effect on oxygen corrosion: it permits higher flow rates without increasing the oxygen corrosion rate.

  6. Effect of temperature on toxicity of deltamethrin and oxygen consumption by Porcellio scaber Latr (Isopoda).

    PubMed

    Unkiewicz-Winiarczyk, Aneta; Gromysz-Kałkowska, Kazimiera

    2012-11-01

    This study describes the toxicity of deltamethrin, in relation to its LD50 value, as well as variation in respiratory metabolism of the isopod species Porcellio scaber Latr kept at 3 temperature values (10, 22 and 30ºC). The low LD50 values obtained indicate that deltamethrin is a highly toxic pyrethroid for the crustacean tested, particularly at 10ºC. We also observed that, in all the 3 experimental temperatures, the deltamethrin toxicity was lower in females than in males. Particularly distinct differences between both sexes were visible at 10 and 30ºC, i.e. temperatures that are too low and too high for the species studied. Oxygen uptake measurement showed an increase in respiratory metabolism directly after intoxication. The most substantial increase, 64% in males and 80% in females, was observed at the temperature 10ºC, whereas at the other temperatures, it did not exceed 20%. During the successive experimental days, the respiratory consumption in P. scaber had a tendency to decrease, which was more visible at 10 and 30ºC, compared to the optimal temperature 22ºC.

  7. Respiratory water loss and oxygen consumption in newborn infants during phototherapy.

    PubMed

    Kjartansson, S; Hammarlund, K; Riesenfeld, T; Sedin, G

    1992-10-01

    Respiratory water loss was measured together with oxygen consumption (VO2) and carbon dioxide production (VCO2) in 11 full-term and eight preterm infants (mean gestational age 34 weeks, range 31-36 weeks) before and during 1 h of phototherapy. The method for determination of respiratory water loss, VO2 and VCO2 was based on an open flow-through system with a mass spectrometer for measurement of gas concentrations. All infants were studied naked in an incubator with an ambient relative humidity of 50% and with a controlled environment with respect to temperature and air velocity. The infants were calm during the measurements. Before phototherapy, in term infants respiratory water loss was 4.4 (SD 0.7) mg/kg min and VO2 5.9 (0.9) ml/kg min and in preterm infants respiratory water loss was 4.7 (0.8) mg/kg min and VO2 6.1 (0.8) ml/kg min. No significant difference was found between values obtained during or after 1 h of phototherapy and those obtained before.

  8. Diffusion and consumption of oxygen in the superfused retina of the drone (Apis mellifera) in darkness.

    PubMed

    Tsacopoulos, M; Poitry, S; Borsellino, A

    1981-06-01

    Double-barreled O2 microelectrodes were used to study O2 diffusion and consumption in the superfused drone (Apis mellifera) retina in darkness at 22 degrees C. Po2 was measured at different sites in the bath and retinas. It was found that diffusion was essentially in one dimension and that the rate of O2 consumption (Q) was practically constant (on the macroscale) down to Po2 s less than 20 mm Hg, a situation that greatly simplified the analysis. The value obtained for Q was 18 +/- 0.7 (SEM) microliter O2/cm3 tissue . min (n = 10), and Krogh's permeation coefficient (alpha D) was 3.24 +/- 0.18 (SEM) X 10(-5) ml O1/min . atm . cm (n = 10). Calculations indicate that only a small fraction of this Q in darkness is necessary for the energy requirements of the sodium pump. the diffusion coefficient (D) in the retina was measured by abruptly cutting off diffusion from the bath and analyzing the time-course of the fall in Po2 at the surface of the tissue. The mean value of D was 1.03 +/- 0.08 (SEM) X 10(-5) cm2/s (n = 10). From alpha D and D, the solubility coefficient alpha was calculated to be 54 +/- 4.0 (SEM) microliter O2 STP/cm3 . atm (n = 10), approximately 1.8 times that for water.

  9. Food consumption and growth rates of juvenile black carp fed natural and prepared feeds

    USGS Publications Warehouse

    Hodgins, Nathaniel C.; Schramm, Harold L.; Gerard, Patrick D.

    2014-01-01

    The introduced mollusciphagic black carp Mylopharyngodon piceus poses a significant threat to native mollusks in temperate waters throughout the northern hemisphere, but consumption rates necessary to estimate the magnitude of impact on mollusks have not been established. We measured food consumption and growth rates for small (77–245 g) and large (466–1,071 g) triploid black carp held individually under laboratory conditions at 20, 25, and 30°C. Daily consumption rates (g food · g wet weight fish−1·d−1·100) of black carp that received prepared feed increased with temperature (small black carp 1.39–1.71; large black carp 1.28–2.10), but temperature-related increases in specific growth rate (100[ln(final weight) - ln(initial weight)]/number of days) only occurred for the large black carp (small black carp −0.02 to 0.19; large black carp 0.16–0.65). Neither daily consumption rates (5.90–6.28) nor specific growth rates (0.05–0.24) differed among temperatures for small black carp fed live snails. The results of these laboratory feeding trials indicate food consumption rates can vary from 289.9 to 349.5 J·g−1·d−1 for 150 g black carp receiving prepared feed, from 268.8 to 441.0 J·g−1·d−1for 800 g black carp receiving prepared feed, and from 84.8 to 90.2 J·g−1·d−1 for 150 g black carp that feed on snails. Applying estimated daily consumption rates to estimated biomass of native mollusks indicates that a relatively low biomass of bla

  10. Acute effects of black currant consumption on salivary flow rate and secretion rate of salivary immunoglobulin a in healthy smokers.

    PubMed

    Konić-Ristić, Aleksandra; Šavikin, Katarina; Zdunić, Gordana; Besu, Irina; Menković, Nebojša; Glibetić, Marija; Srdić-Rajić, Tatjana

    2015-04-01

    The role of saliva in maintaining oral health and homeostasis is based on its physicochemical properties and biological activities of its components, including salivary immunoglobulin A (IgA). Both salivary rates and immunological status of saliva are found to be compromised in smokers. The aim of this study was to investigate the acute time-dependent effect of smoking and black currant consumption on the salivary flow rate (SFR) and salivary IgA secretion rate (sIgA SR) in healthy smokers. SFR, sIgA levels in saliva, and sIgA SRs were determined in healthy smokers (n=8) at eight times of assessment within three consecutive interventions: at the baseline; 5, 30, and 60 min after smoking; 5, 30, and 60 min after black currant consumption (100 g), followed by smoking; and 5 min after black currant consumption. Smoking induced a significant delayed effect on SFR measured 60 min after smoking (P=.03), while black currant consumption preceding smoking prevented that effect. Salivary IgA concentrations and sIgA flow rates were not acutely influenced by smoking. Black currant consumption preceding smoking induced a significant decrease in sIgA concentrations 5 min after the intervention compared with the baseline (P=.046), with a further increasing trend, statistically significant, 60 min after the intervention (P=.025). Although smoking cessation is the most important strategy in the prevention of chronic diseases, the obtained results suggest that the influence of black currant consumption on negative effects of tobacco smoke on salivary flow and immunological status of saliva could partly reduce the smoking-associated risk on oral health.

  11. A New Highly Sensitive Method to Assess Respiration Rates and Kinetics of Natural Planktonic Communities by Use of the Switchable Trace Oxygen Sensor and Reduced Oxygen Concentrations

    PubMed Central

    Tiano, Laura; Garcia-Robledo, Emilio; Revsbech, Niels Peter

    2014-01-01

    Oxygen respiration rates in pelagic environments are often difficult to quantify as the resolutions of our methods for O2 concentration determination are marginal for observing significant decreases during bottle incubations of less than 24 hours. Here we present the assessment of a new highly sensitive method, that combine Switchable Trace Oxygen (STOX) sensors and all-glass bottle incubations, where the O2 concentration was artificially lowered. The detection limit of respiration rate by this method is inversely proportional to the O2 concentration, down to <2 nmol L−1 h−1 for water with an initial O2 concentration of 500 nmol L−1. The method was tested in Danish coastal waters and in oceanic hypoxic waters. It proved to give precise measurements also with low oxygen consumption rates (∼7 nmol L−1 h−1), and to significantly decrease the time required for incubations (≤14 hours) compared to traditional methods. This method provides continuous real time measurements, allowing for a number of diverse possibilities, such as modeling the rate of oxygen decrease to obtain kinetic parameters. Our data revealed apparent half-saturation concentrations (Km values) one order of magnitude lower than previously reported for marine bacteria, varying between 66 and 234 nmol L−1 O2. Km values vary between different microbial planktonic communities, but our data show that it is possible to measure reliable respiration rates at concentrations ∼0.5–1 µmol L−1 O2 that are comparable to the ones measured at full air saturation. PMID:25127458

  12. Cerebral metabolic rate of oxygen (CMRO2) assessed by combined Doppler and spectroscopic OCT

    PubMed Central

    Chong, Shau Poh; Merkle, Conrad W.; Leahy, Conor; Srinivasan, Vivek J.

    2015-01-01

    A method of measuring cortical oxygen metabolism in the mouse brain that uses independent quantitative measurements of three key parameters: cerebral blood flow (CBF), arteriovenous oxygen extraction (OE), and hemoglobin concentration ([HbT]) is presented. Measurements were performed using a single visible light spectral/Fourier domain OCT microscope, with Doppler and spectroscopic capabilities, through a thinned-skull cranial window in the mouse brain. Baseline metabolic measurements in mice are shown to be consistent with literature values. Oxygen consumption, as measured by this method, did not change substantially during minor changes either in the fraction of inspired oxygen (FiO2) or in the fraction of inspired carbon dioxide (FiCO2), in spite of larger variations in oxygen saturations. This set of experiments supports, but does not prove, the validity of the proposed method of measuring brain oxygen metabolism. PMID:26504644

  13. Atmospheric oxygen level affects growth trajectory, cardiopulmonary allometry and metabolic rate in the American alligator (Alligator mississippiensis)

    PubMed Central

    Owerkowicz, Tomasz; Elsey, Ruth M.; Hicks, James W.

    2009-01-01

    Summary Recent palaeoatmospheric models suggest large-scale fluctuations in ambient oxygen level over the past 550 million years. To better understand how global hypoxia and hyperoxia might have affected the growth and physiology of contemporary vertebrates, we incubated eggs and raised hatchlings of the American alligator. Crocodilians are one of few vertebrate taxa that survived these global changes with distinctly conservative morphology. We maintained animals at 30°C under chronic hypoxia (12% O2), normoxia (21% O2) or hyperoxia (30% O2). At hatching, hypoxic animals were significantly smaller than their normoxic and hyperoxic siblings. Over the course of 3 months, post-hatching growth was fastest under hyperoxia and slowest under hypoxia. Hypoxia, but not hyperoxia, caused distinct scaling of major visceral organs–reduction of liver mass, enlargement of the heart and accelerated growth of lungs. When absorptive and post-absorptive metabolic rates were measured in juvenile alligators, the increase in oxygen consumption rate due to digestion/absorption of food was greatest in hyperoxic alligators and smallest in hypoxic ones. Hyperoxic alligators exhibited the lowest breathing rate and highest oxygen consumption per breath. We suggest that, despite compensatory cardiopulmonary remodelling, growth of hypoxic alligators is constrained by low atmospheric oxygen supply, which may limit their food utilisation capacity. Conversely, the combination of elevated metabolism and low cost of breathing in hyperoxic alligators allows for a greater proportion of metabolised energy to be available for growth. This suggests that growth and metabolic patterns of extinct vertebrates would have been significantly affected by changes in the atmospheric oxygen level. PMID:19376944

  14. 1α,25-Dihydroxyvitamin D3 Regulates Mitochondrial Oxygen Consumption and Dynamics in Human Skeletal Muscle Cells.

    PubMed

    Ryan, Zachary C; Craig, Theodore A; Folmes, Clifford D; Wang, Xuewei; Lanza, Ian R; Schaible, Niccole S; Salisbury, Jeffrey L; Nair, K Sreekumaran; Terzic, Andre; Sieck, Gary C; Kumar, Rajiv

    2016-01-15

    Muscle weakness and myopathy are observed in vitamin D deficiency and chronic renal failure, where concentrations of the active vitamin D3 metabolite, 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3), are low. To evaluate the mechanism of action of 1α,25(OH)2D3 in skeletal muscle, we examined mitochondrial oxygen consumption, dynamics, and biogenesis and changes in expression of nuclear genes encoding mitochondrial proteins in human skeletal muscle cells following treatment with 1α,25(OH)2D3. The mitochondrial oxygen consumption rate (OCR) increased in 1α,25(OH)2D3-treated cells. Vitamin D3 metabolites lacking a 1α-hydroxyl group (vitamin D3, 25-hydroxyvitamin D3, and 24R,25-dihydroxyvitamin D3) decreased or failed to increase OCR. 1α-Hydroxyvitamin D3 did not increase OCR. In 1α,25(OH)2D3-treated cells, mitochondrial volume and branching and expression of the pro-fusion protein OPA1 (optic atrophy 1) increased, whereas expression of the pro-fission proteins Fis1 (fission 1) and Drp1 (dynamin 1-like) decreased. Phosphorylated pyruvate dehydrogenase (PDH) (Ser-293) and PDH kinase 4 (PDK4) decreased in 1α,25(OH)2D3-treated cells. There was a trend to increased PDH activity in 1α,25(OH)2D3-treated cells (p = 0.09). 83 nuclear mRNAs encoding mitochondrial proteins were changed following 1α,25(OH)2D3 treatment; notably, PDK4 mRNA decreased, and PDP2 mRNA increased. MYC, MAPK13, and EPAS1 mRNAs, which encode proteins that regulate mitochondrial biogenesis, were increased following 1α,25(OH)2D3 treatment. Vitamin D receptor-dependent changes in the expression of 1947 mRNAs encoding proteins involved in muscle contraction, focal adhesion, integrin, JAK/STAT, MAPK, growth factor, and p53 signaling pathways were observed following 1α,25(OH)2D3 treatment. Five micro-RNAs were induced or repressed by 1α,25(OH)2D3. 1α,25(OH)2D3 regulates mitochondrial function, dynamics, and enzyme function, which are likely to influence muscle strength. PMID:26601949

  15. 1α,25-Dihydroxyvitamin D3 Regulates Mitochondrial Oxygen Consumption and Dynamics in Human Skeletal Muscle Cells.

    PubMed

    Ryan, Zachary C; Craig, Theodore A; Folmes, Clifford D; Wang, Xuewei; Lanza, Ian R; Schaible, Niccole S; Salisbury, Jeffrey L; Nair, K Sreekumaran; Terzic, Andre; Sieck, Gary C; Kumar, Rajiv

    2016-01-15

    Muscle weakness and myopathy are observed in vitamin D deficiency and chronic renal failure, where concentrations of the active vitamin D3 metabolite, 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3), are low. To evaluate the mechanism of action of 1α,25(OH)2D3 in skeletal muscle, we examined mitochondrial oxygen consumption, dynamics, and biogenesis and changes in expression of nuclear genes encoding mitochondrial proteins in human skeletal muscle cells following treatment with 1α,25(OH)2D3. The mitochondrial oxygen consumption rate (OCR) increased in 1α,25(OH)2D3-treated cells. Vitamin D3 metabolites lacking a 1α-hydroxyl group (vitamin D3, 25-hydroxyvitamin D3, and 24R,25-dihydroxyvitamin D3) decreased or failed to increase OCR. 1α-Hydroxyvitamin D3 did not increase OCR. In 1α,25(OH)2D3-treated cells, mitochondrial volume and branching and expression of the pro-fusion protein OPA1 (optic atrophy 1) increased, whereas expression of the pro-fission proteins Fis1 (fission 1) and Drp1 (dynamin 1-like) decreased. Phosphorylated pyruvate dehydrogenase (PDH) (Ser-293) and PDH kinase 4 (PDK4) decreased in 1α,25(OH)2D3-treated cells. There was a trend to increased PDH activity in 1α,25(OH)2D3-treated cells (p = 0.09). 83 nuclear mRNAs encoding mitochondrial proteins were changed following 1α,25(OH)2D3 treatment; notably, PDK4 mRNA decreased, and PDP2 mRNA increased. MYC, MAPK13, and EPAS1 mRNAs, which encode proteins that regulate mitochondrial biogenesis, were increased following 1α,25(OH)2D3 treatment. Vitamin D receptor-dependent changes in the expression of 1947 mRNAs encoding proteins involved in muscle contraction, focal adhesion, integrin, JAK/STAT, MAPK, growth factor, and p53 signaling pathways were observed following 1α,25(OH)2D3 treatment. Five micro-RNAs were induced or repressed by 1α,25(OH)2D3. 1α,25(OH)2D3 regulates mitochondrial function, dynamics, and enzyme function, which are likely to influence muscle strength.

  16. Noninvasive estimation of regional myocardial oxygen consumption by positron emission tomography with carbon-11 acetate in patients with myocardial infarction

    SciTech Connect

    Walsh, M.N.; Geltman, E.M.; Brown, M.A.; Henes, C.G.; Weinheimer, C.J.; Sobel, B.E.; Bergmann, S.R. )

    1989-11-01

    We previously demonstrated in experimental studies that myocardial oxygen consumption (MVO2) can be estimated noninvasively with positron emission tomography (PET) from analysis of the myocardial turnover rate constant (k) after administration of carbon-11 (11C) acetate. To determine regional k in healthy human subjects and to estimate alterations in MVO2 accompanying myocardial ischemia, we administered (11C)acetate to five healthy human volunteers and to six patients with myocardial infarction. Extraction of (11C)acetate by the myocardium was avid and clearance from the blood-pool rapid yielding myocardial images of excellent quality. Regional k was homogeneous in myocardium of healthy volunteers (coefficient variation = 11%). In patients, k in regions remote from the area of infarction was not different from values in myocardium of healthy human volunteers (0.061 +/- 0.025 compared with 0.057 +/- 0.008 min-1). In contrast, MVO2 in the center of the infarct region was only 6% of that in remote regions (p less than 0.01). In four patients studied within 48 hr of infarction and again more than seven days after the acute event, regional k and MVO2 did not change. The approach developed should facilitate evaluation of the efficacy of interventions designed to enhance recovery of jeopardized myocardium and permit estimation of regional MVO2 and metabolic reserve underlying cardiac disease of diverse etiologies.

  17. A multistage field test of wheelchair users for evaluation of fitness and prediction of peak oxygen consumption.

    PubMed

    Vanderthommen, Marc; Francaux, Marc; Colinet, Cédrik; Lehance, Cédric; Lhermerout, Claude; Crielaard, Jean-Michel; Theisen, Daniel

    2002-01-01

    An incremental multistage field test (MFT) for wheelchair users was developed to evaluate physical fitness and predict peak oxygen consumption (VO2). Using auditory feedback, the participants (n = 37) were directed to wheel around an octagonal course, increasing their velocity every minute until exhaustion. Wheelchair velocity and metabolic parameters were recorded with the use of a speedometer and a portable spirometer system. The average number of exercise levels performed (MFT score) was 9.17 +/- 5.81, resulting in a peak heart rate (HR) of 99.0 +/- 13.9% of the theoretical maximum. A test-retest analysis (n = 10) showed that the MFT was reliable regarding MFT score, peak VO2, and peak HR reached. Stepwise multiple regression based on individual, wheelchair, propulsion technique, and physiological parameters revealed that the MFT score was the best and only predictor of peak VO2 (mL/min/kg) (= 18.03 + 0.78 MFT score, r(2) = 0.59). The MFT assesses wheelchair mobility and estimates peak VO2 encountered during the test. PMID:17943670

  18. Pedaling rate is an important determinant of human oxygen uptake during exercise on the cycle ergometer.

    PubMed

    Formenti, Federico; Minetti, Alberto E; Borrani, Fabio

    2015-09-01

    Estimation of human oxygen uptake (V˙o2) during exercise is often used as an alternative when its direct measurement is not feasible. The American College of Sports Medicine (ACSM) suggests estimating human V˙o2 during exercise on a cycle ergometer through an equation that considers individual's body mass and external work rate, but not pedaling rate (PR). We hypothesized that including PR in the ACSM equation would improve its V˙o2 prediction accuracy. Ten healthy male participants' (age 19-48 years) were recruited and their steady-state V˙o2 was recorded on a cycle ergometer for 16 combinations of external work rates (0, 50, 100, and 150 W) and PR (50, 70, 90, and 110 revolutions per minute). V˙o2 was calculated by means of a new equation, and by the ACSM equation for comparison. Kinematic data were collected by means of an infrared 3-D motion analysis system in order to explore the mechanical determinants of V˙o2. Including PR in the ACSM equation improved the accuracy for prediction of sub-maximal V˙o2 during exercise (mean bias 1.9 vs. 3.3 mL O2 kg(-1) min(-1)) but it did not affect the accuracy for prediction of maximal V˙o2 (P > 0.05). Confirming the validity of this new equation, the results were replicated for data reported in the literature in 51 participants. We conclude that PR is an important determinant of human V˙o2 during cycling exercise, and it should be considered when predicting oxygen consumption.

  19. Kinetics of oxygen consumption after a single flash of light in photoreceptors of the drone (Apis mellifera)

    PubMed Central

    1982-01-01

    The time course of the rate of oxygen consumption (QO2) after a single flash of light has been measured in 300-micrometers slices of drone retina at 22 degrees C. To measure delta QO2(t), the change in QO2 from its level in darkness, the transients of the partial pressure of O2 (PO2) were recorded with O2 microelectrodes simultaneously in two sites in the slice and delta QO2 was calculated by a computer using Fourier transforms. After a 40-ms flash of intense light, delta QO2, reached a peak of 40 microliters O2/g.min and then declined exponentially to the baseline with a time constant tau 1 = 4.96 +/- 0.49 s (SD, n = 10). The rising phase was characterized by a time constant tau 2 = 1.90 +/- 0.35 s (SD, n = 10). The peak amplitude of delta QO2 increased linearly with the log of the light intensity. Replacement of Na+ by choline, known to decrease greatly the light-induced transmembrane current, caused a 63% decrease of delta QO2. With these changes, however, the kinetics of delta QO2 (t) were unchanged. This suggest that the recovery phase is rate-limited by a single reaction with apparent first-order kinetics. Evidence is provided that suggests that this reaction may be the working of the sodium pump. Exposure of the retina to high concentrations of ouabain or strophanthidin (inhibitors of the sodium pump) reduced the peak amplitude of delta QO2 by approximately 80% and increased tau 1. The increase of tau 1 was an exponential function of the time of exposure to the cardioactive steroids. Hence, it seems likely that the greatest part of delta QO2 is used for the working of the pump, whose activity is the mechanism underlying the rate constant of the descending limb of delta QO2 (t). PMID:6288837

  20. Kinetics of oxygen consumption after a single flash of light in photoreceptors of the drone (Apis mellifera).

    PubMed

    Tsacopoulos, M; Poitry, S

    1982-07-01

    The time course of the rate of oxygen consumption (QO2) after a single flash of light has been measured in 300-micrometers slices of drone retina at 22 degrees C. To measure delta QO2(t), the change in QO2 from its level in darkness, the transients of the partial pressure of O2 (PO2) were recorded with O2 microelectrodes simultaneously in two sites in the slice and delta QO2 was calculated by a computer using Fourier transforms. After a 40-ms flash of intense light, delta QO2, reached a peak of 40 microliters O2/g.min and then declined exponentially to the baseline with a time constant tau 1 = 4.96 +/- 0.49 s (SD, n = 10). The rising phase was characterized by a time constant tau 2 = 1.90 +/- 0.35 s (SD, n = 10). The peak amplitude of delta QO2 increased linearly with the log of the light intensity. Replacement of Na+ by choline, known to decrease greatly the light-induced transmembrane current, caused a 63% decrease of delta QO2. With these changes, however, the kinetics of delta QO2 (t) were unchanged. This suggest that the recovery phase is rate-limited by a single reaction with apparent first-order kinetics. Evidence is provided that suggests that this reaction may be the working of the sodium pump. Exposure of the retina to high concentrations of ouabain or strophanthidin (inhibitors of the sodium pump) reduced the peak amplitude of delta QO2 by approximately 80% and increased tau 1. The increase of tau 1 was an exponential function of the time of exposure to the cardioactive steroids. Hence, it seems likely that the greatest part of delta QO2 is used for the working of the pump, whose activity is the mechanism underlying the rate constant of the descending limb of delta QO2 (t).

  1. Improving consumption rate estimates by incorporating wild activity into a bioenergetics model.

    PubMed

    Brodie, Stephanie; Taylor, Matthew D; Smith, James A; Suthers, Iain M; Gray, Charles A; Payne, Nicholas L

    2016-04-01

    Consumption is the basis of metabolic and trophic ecology and is used to assess an animal's trophic impact. The contribution of activity to an animal's energy budget is an important parameter when estimating consumption, yet activity is usually measured in captive animals. Developments in telemetry have allowed the energetic costs of activity to be measured for wild animals; however, wild activity is seldom incorporated into estimates of consumption rates. We calculated the consumption rate of a free-ranging marine predator (yellowtail kingfish, Seriola lalandi) by integrating the energetic cost of free-ranging activity into a bioenergetics model. Accelerometry transmitters were used in conjunction with laboratory respirometry trials to estimate kingfish active metabolic rate in the wild. These field-derived consumption rate estimates were compared with those estimated by two traditional bioenergetics methods. The first method derived routine swimming speed from fish morphology as an index of activity (a "morphometric" method), and the second considered activity as a fixed proportion of standard metabolic rate (a "physiological" method). The mean consumption rate for free-ranging kingfish measured by accelerometry was 152 J·g(-1)·day(-1), which lay between the estimates from the morphometric method (μ = 134 J·g(-1)·day(-1)) and the physiological method (μ = 181 J·g(-1)·day(-1)). Incorporating field-derived activity values resulted in the smallest variance in log-normally distributed consumption rates (σ = 0.31), compared with the morphometric (σ = 0.57) and physiological (σ = 0.78) methods. Incorporating field-derived activity into bioenergetics models probably provided more realistic estimates of consumption rate compared with the traditional methods, which may further our understanding of trophic interactions that underpin ecosystem-based fisheries management. The general methods used to estimate active metabolic rates of free-ranging fish

  2. Effect of Exercise Training on Peak Oxygen Consumption in Patients with Cancer: A Meta-Analysis

    PubMed Central

    Liang, Yuanyuan; Pituskin, Edith N.; Battaglini, Claudio L.; Scott, Jessica M.; Hornsby, Whitney E.; Haykowsky, Mark

    2011-01-01

    Background. We conducted a meta-analysis to determine the effects of supervised exercise training on peak oxygen consumption (VO2peak) in adults with cancer. Methods. A literature review using Ovid MEDLINE (1950–2010), the Cochrane Central Register of Controlled Trials (1991–2010), AMED (1985–2010), Embase (1988–2010), PubMed (1966–2010), Scopus (1950–2010), and Web of Science (1950–2010) was performed to identify randomized controlled trials examining the effects of supervised exercise training on measurement of VO2peak (via gas exchange analysis) in adults with cancer. Studies were selected using predetermined criteria, and two independent reviewers extracted data. Weighted mean differences (WMDs) were calculated using random effect models. Results. Six studies evaluated VO2peak involving a total of 571 adult cancer patients (exercise, n = 344; usual care control, n = 227). Pooled data indicated that exercise training was associated with a statistically significant increase in VO2peak (WMD, 2.90 ml·kg−1·min−1; 95% confidence interval [CI], 1.16–4.64); however, significant heterogeneity was evident in this estimate (I2, 87%). Usual care (control) was associated with a significant decline in VO2peak from baseline to postintervention (WMD, −1.02 ml·kg−1·min−1; 95% CI, −1.46 to −0.58; I2, 22%). Sensitivity analyses indicated superior improvements in VO2peak for studies conducted for a shorter duration (<4 months) and following the completion of adjuvant therapy (p-values < .001). Exercise training was not associated with a higher incidence of adverse events, although safety was not rigorously monitored or reported. Conclusions. Supervised exercise training is associated with significant improvements in VO2peak following a diagnosis of early-stage cancer, with minimal adverse events. PMID:21212429

  3. Determinants of oxygen consumption during exercise on cycle ergometer: the effects of gravity acceleration.

    PubMed

    Bonjour, Julien; Capelli, Carlo; Antonutto, Guglielmo; Calza, Stefano; Tam, Enrico; Linnarsson, Dag; Ferretti, Guido

    2010-04-30

    The hypothesis that changes in gravity acceleration (a(g)) affect the linear relationships between oxygen consumption VO2 and mechanical power (w ) so that at any w, VO2 increases linearly with a(g) was tested under conditions where the weight of constant-mass legs was let to vary by inducing changes in a(g) in a human centrifuge. The effects of a(g) on the VO2/w relationship were studied on 14 subjects at two pedalling frequencies (f(p), 1.0 and 1.5 Hz), during four work loads on a cycle ergometer (25, 50, 75 and 100 W) and at four a(g) levels (1.0, 1.5, 2.0 and 2.5 times normal gravity). VO2 increased linearly with w. The slope did not differ significantly at various a(g) and f(p), suggesting invariant mechanical efficiency during cycling, independent of f(p) and a(g). Conversely, the y-intercept of the VO2/w relationship, defined as constant b, increased linearly with a(g). Constant b is the sum of resting VO2 plus internal metabolic power (E (i)). Since the former was the same at all investigated a(g), the increase in constant b was entirely due to an increase in E (i). Since the VO2 versus w lines had similar slopes, the changes in E (i) entirely explained the higher VO2 at each w, as a(g) was increased. In conclusion, the effects of a(g) on VO2 are mediated through changes in E (i), and not in w or in resting VO2.

  4. Enzymatic assay of total cholesterol in serum or plasma by amperometric measurement of rate of oxygen depletion following saponification.

    PubMed

    Kumar, A; Christian, G D

    1977-01-17

    A method for serum or plasma cholesterol assay involving amperometric measurement of the rate of oxygen depletion in the cholesterol oxidase-catalyzed oxidation of cholesterol is described. The hydrolysis of the serum cholesterol esters is accomplished by saponification of 50 mul of sample with 0.2 ml of ethanolic KOH (1.0 mol/1) containing 0.5% Triton X-100 for 5 min at 75 degrees C. The rate of oxygen consumption in a 25-mul aliquot of this is measured with a Clark electrode in a Beckman Glucose Analyzer and the assay takes about one minute after incubation; results are read digitally on the instrument. The analyzer cell contains 1 ml of 1 M phosphate buffer, pH 7.4, with 100 mg sodium cholate/100 ml and 0.1-0.2 U cholesterol oxidase.

  5. Oxygen consumption and active sodium and chloride transport in bovine tracheal epithelium.

    PubMed Central

    Durand, J; Durand-Arczynska, W; Schoenenweid, F

    1986-01-01

    The O2 consumption (Jr) and the short-circuit current (Ji) were measured simultaneously in bovine tracheal epithelium in vitro. In this tissue, Ji is the sum of two active transport processes, Cl- secretion and Na+ absorption. Jr was determined from the decrease of PO2 in the incubation solution, at 37 +/- 0.05 degrees C and at a PO2 around 600 torr. Microbial contamination and leaks of dissolved O2 from the solution never exceeded 4% of the rate of PO2 decrease due to the O2 consumption of the tissue. Ji and Jr were stable over 5 h of incubation under standard conditions. Ji was 106 +/- 4 nequiv min-1 cm-2 and Jr was 39.8 +/- 1.1 nmol O2 min-1 cm-2 (mean +/- S.E., n = 46). Ji was varied with several agents known to affect ion transport across the tracheal epithelium. Na+ absorption was inhibited partly with amiloride or completely following Na+ substitution with choline. Cl- secretion was selectively suppressed by furosemide. Ji was also reduced to a very low level, using ouabain or K+ suppression to inhibit the Na+-K+-ATPase. All these manoeuvres resulted in significant reductions of both Ji and Jr. Basal Jr was not affected when Ji was modified. A plot of the relative change in suprabasal Jr versus the relative change of Ji gave a straight line (r = 0.98, n = 60). A plot using absolute values yielded a stoichiometric ratio of 13.9 ions per O2 molecule, for Na+ as well as for Cl-. The stoichiometric ratio was also calculated for each experiment. Its mean value was 14.9 ions per O2 molecule. The population of the ratios was widely dispersed, but this was explained as a predictable statistical phenomenon. PMID:3723416

  6. [Evaluation of heart impact in the 100 m extreme intensity sport using near-infrared non-invasive muscle oxygen detecting device and sports heart rate detection technology].

    PubMed

    Wang, Pei-Yong; Long, Fei-Xiao; Fu, Lan-Ying; Li, Yue; Ding, Hai-Shu; Qu, An-Lian; Zhou, Xiao-Ping

    2010-02-01

    Using continuous two wavelength near-infrared technology to detect the variation in the consistency of oxygen hemoglobin in the muscle and the sports heart rate wireless real time collection technology, we devised the real time muscle tissue oxygenation and instantaneous heart rate experiment scheme and implemented it for the process of the 100 m run with two parameters given simultaneously. The experiment shows that the concentration of the oxygen hemoglobin in the muscle tissue continues decreasing after the end of the 100 m run, and the time interval between the moment when the concentration of the oxygen hemoglobin attains the minimum value and the moment when the athletes finish the 100 m run is (6.65 +/- 1.10) sec; while the heart rate continues increasing after the end of the 100 m run, and the time interval between the moment when the heart rate attains the maximum value and the moment when the athletes finish the 100 m run is (8.00 +/- 1.57) sec. The results show that the two wavelength near-infrared tissue oxygenation detection technology and the sports heart rate real time collection equipment can accurately measure the sports tissue oxygenation and the heart rate in the extreme intensity sport, and reveal the process of muscle oxygen transportation and consumption and its dynamic character with the heart rate in the extreme intensity sport.

  7. Tritium-helium dating in the sargasso sea: a measurement of oxygen utilization rates.

    PubMed

    Jenkins, W J

    1977-04-15

    The newly developed technique of "tritium-helium dating" has been used to investigate in situ rates of oceanic oxygen utilization. As an example, an apparent oxygen utilization rate of 0.20 +/- 0.02 milliliter per liter of water per year has been obtained for the Subtropical Mode water (18 degrees C water) in the Sargasso Sea.

  8. A new layered sensor for simultaneous measurement of EMG, MMG and oxygen consumption at the same position.

    PubMed

    Kimoto, Akira; Yamada, Yuji

    2015-01-01

    A new layered sensor for simultaneous measurement of electromyography (EMG), mechanomyography (MMG) and oxygen consumption based on near-infrared spectroscopy (NIRS) at the same position of the muscle is presented. The proposed sensor is a layered structure of a thin stainless-steel electrode, a PVDF film with transparent electrodes and optical sensors. EMG, MMG and oxygen consumption based on NIRS are measured by the stainless-steel electrodes, PVDF film and optical sensors, respectively. Using the three types of data, muscular activity can be analyzed in more detail. Additionally, the proposed sensor system reduces the constraint of the sensors arranged on the skin in measurements at multiple points because three types of information, previously obtained with three types of general sensors, are detected by a pair of proposed sensors. In an experiment, simultaneous measurement of EMG, MMG and oxygen consumption via NIRS at the forearm was demonstrated using the proposed sensor under fluorescent light. The performance of the layered sensor was evaluated.

  9. A new layered sensor for simultaneous measurement of EMG, MMG and oxygen consumption at the same position.

    PubMed

    Kimoto, Akira; Yamada, Yuji

    2015-01-01

    A new layered sensor for simultaneous measurement of electromyography (EMG), mechanomyography (MMG) and oxygen consumption based on near-infrared spectroscopy (NIRS) at the same position of the muscle is presented. The proposed sensor is a layered structure of a thin stainless-steel electrode, a PVDF film with transparent electrodes and optical sensors. EMG, MMG and oxygen consumption based on NIRS are measured by the stainless-steel electrodes, PVDF film and optical sensors, respectively. Using the three types of data, muscular activity can be analyzed in more detail. Additionally, the proposed sensor system reduces the constraint of the sensors arranged on the skin in measurements at multiple points because three types of information, previously obtained with three types of general sensors, are detected by a pair of proposed sensors. In an experiment, simultaneous measurement of EMG, MMG and oxygen consumption via NIRS at the forearm was demonstrated using the proposed sensor under fluorescent light. The performance of the layered sensor was evaluated. PMID:25300403

  10. High- and moderate-intensity aerobic exercise and excess post-exercise oxygen consumption in men with metabolic syndrome.

    PubMed

    Larsen, I; Welde, B; Martins, C; Tjønna, A E

    2014-06-01

    Physical activity is central in prevention and treatment of metabolic syndrome. High-intensity aerobic exercise can induce larger energy expenditure per unit of time compared with moderate-intensity exercise. Furthermore, it may induce larger energy expenditure at post-exercise recovery. The aim of this study is to compare the excess post-exercise oxygen consumption (EPOC) in three different aerobic exercise sessions in men with metabolic syndrome. Seven men (age: 56.7 ± 10.8) with metabolic syndrome participated in this crossover study. The sessions consisted of one aerobic interval (1-AIT), four aerobic intervals (4-AIT), and 47-min continuous moderate exercise (CME) on separate days, with at least 48 h between each test day. Resting metabolic rate (RMR) was measured pre-exercise and used as baseline value. EPOC was measured until baseline metabolic rate was re-established. An increase in O2 uptake lasting for 70.4 ± 24.8 min (4-AIT), 35.9 ± 17.3 min (1-AIT), and 45.6 ± 17.3 min (CME) was observed. EPOC were 2.9 ± 1.7 L O2 (4-AIT), 1.3 ±  .1 L O2 (1-AIT), and 1.4 ± 1.1 L O2 (CME). There were significant differences (P < 0.001) between 4-AIT, CME, and 1-AIT. Total EPOC was highest after 4-AIT. These data suggest that exercise intensity has a significant positive effect on EPOC in men with metabolic syndrome.

  11. Excess post-exercise oxygen consumption in adult sockeye (Oncorhynchus nerka) and coho (O. kisutch) salmon following critical speed swimming.

    PubMed

    Lee, C G; Farrell, A P; Lotto, A; Hinch, S G; Healey, M C

    2003-09-01

    The present study measured the excess post-exercise oxygen cost (EPOC) following tests at critical swimming speed (Ucrit) in three stocks of adult, wild, Pacific salmon (Oncorhynchus sp.) and used EPOC to estimate the time required to return to their routine level of oxygen consumption (recovery time) and the total oxygen cost of swimming to Ucrit. Following exhaustion at Ucrit, recovery time was 42-78 min, depending upon the fish stock. The recovery times are several-fold shorter than previously reported for juvenile, hatchery-raised salmonids. EPOC varied fivefold among the fish stocks, being greatest for Gates Creek sockeye salmon (O. nerka), which was the salmon stock that had the longest in-river migration, experienced the warmest temperature and achieved the highest maximum oxygen consumption compared with the other salmon stocks that were studied. EPOC was related to Ucrit, which in turn was directly influenced by ambient test temperature. The non-aerobic cost of swimming to Ucrit was estimated to add an additional 21.4-50.5% to the oxygen consumption measured at Ucrit. While these non-aerobic contributions to swimming did not affect the minimum cost of transport, they were up to three times higher than the value used previously for an energetic model of salmon migration in the Fraser River, BC, Canada. As such, the underestimate of non-aerobic swimming costs may require a reevaluation of the importance of how in-river barriers like rapids and bypass facilities at dams, and year-to-year changes in river flows and temperatures, affect energy use and hence migration success.

  12. Excess post-exercise oxygen consumption in adult sockeye (Oncorhynchus nerka) and coho (O. kisutch) salmon following critical speed swimming.

    PubMed

    Lee, C G; Farrell, A P; Lotto, A; Hinch, S G; Healey, M C

    2003-09-01

    The present study measured the excess post-exercise oxygen cost (EPOC) following tests at critical swimming speed (Ucrit) in three stocks of adult, wild, Pacific salmon (Oncorhynchus sp.) and used EPOC to estimate the time required to return to their routine level of oxygen consumption (recovery time) and the total oxygen cost of swimming to Ucrit. Following exhaustion at Ucrit, recovery time was 42-78 min, depending upon the fish stock. The recovery times are several-fold shorter than previously reported for juvenile, hatchery-raised salmonids. EPOC varied fivefold among the fish stocks, being greatest for Gates Creek sockeye salmon (O. nerka), which was the salmon stock that had the longest in-river migration, experienced the warmest temperature and achieved the highest maximum oxygen consumption compared with the other salmon stocks that were studied. EPOC was related to Ucrit, which in turn was directly influenced by ambient test temperature. The non-aerobic cost of swimming to Ucrit was estimated to add an additional 21.4-50.5% to the oxygen consumption measured at Ucrit. While these non-aerobic contributions to swimming did not affect the minimum cost of transport, they were up to three times higher than the value used previously for an energetic model of salmon migration in the Fraser River, BC, Canada. As such, the underestimate of non-aerobic swimming costs may require a reevaluation of the importance of how in-river barriers like rapids and bypass facilities at dams, and year-to-year changes in river flows and temperatures, affect energy use and hence migration success. PMID:12909706

  13. Relation of myocardial oxygen consumption and function to high energy phosphate utilization during graded hypoxia and reoxygenation in sheep in vivo.

    PubMed Central

    Portman, M A; Standaert, T A; Ning, X H

    1995-01-01

    This study investigates the relation between myocardial oxygen consumption (MVO2), function, and high energy phosphates during severe hypoxia and reoxygenation in sheep in vivo. Graded hypoxia was performed in open-chested sheep to adjust PO2 to values where rapid depletion of energy stores occurred. Highly time-resolved 31P nuclear magnetic resonance spectroscopy enabled monitoring of myocardial phosphates throughout hypoxia and recovery with simultaneous MVO2 measurement. Sheep undergoing graded hypoxia (n = 5) with an arterial PO2 nadir of 13.4 +/- 0.5 mmHg, demonstrated maintained rates of oxygen consumption with large changes in coronary flow as phosphocreatine (PCr) decreased within 4 min to 40 +/- 7% of baseline. ATP utilization rate increased simultaneously 59 +/- 20%. Recovery was accompanied by marked increases in MVO2 from 2.0 +/- 0.5 to 7.2 +/- 1.9 mumol/g per min, while PCr recovery rate was 4.3 +/- 0.6 mumol/g per min. ATP decreased to 75 +/- 6% of baseline during severe hypoxia and did not recover. Sheep (n = 5) which underwent moderate hypoxia (PO2 maintained 25-35 mmHg for 10 min) did not demonstrate change in PCr or ATP. Functional and work assessment (n = 4) revealed that cardiac power increased during the graded hypoxia and was maintained through early reoxygenation. These studies show that (a) MVO2 does not decrease during oxygen deprivation in vivo despite marked and rapid decreases in high energy phosphates; (b) contractile function during hypoxia in vivo does not decrease during periods of PCr depletion and intracellular phosphate accumulation, and this may be related to marked increases in circulating catecholamines during global hypoxia. The measured creatine rephosphorylation rate is 34 +/- 11% of predicted (P < 0.01) calculated from reoxygenation parameters, which indicates that some mitochondrial respiratory uncoupling also occurs during the rephosphorylation period. Images PMID:7738181

  14. Oxygen analyzers: failure rates and life spans of galvanic cells.

    PubMed

    Meyer, R M

    1990-07-01

    Competing technologies exist for measuring oxygen concentrations in breathing circuits. Over a 4-year period, two types of oxygen analyzers were studied prospectively in routine clinical use to determine the incidence and nature of malfunctions. Newer AC-powered galvanic analyzers (North American Dräger O2med) were compared with older, battery-powered polarographic analyzers (Ohmeda 201) by recording all failures and necessary repairs. The AC-powered galvanic analyzer had a significantly lower incidence of failures (0.12 +/- 0.04 failures per machine-month) than the battery-powered polarographic analyzer (4.0 +/- 0.3 failures per machine-month). Disposable capsules containing the active galvanic cells lasted 12 +/- 7 months. Although the galvanic analyzers tended to remain out of service longer, awaiting the arrival of costly parts, the polarographic analyzers were more expensive to keep operating when calculations included the cost of time spent on repairs. Stocking galvanic capsules would have decreased the amount of time the galvanic analyzers were out of service, while increasing costs. In conclusion, galvanic oxygen analyzers appear capable of delivering more reliable service at a lower overall cost. By keeping the galvanic capsules exposed to room air during periods of storage, it should be possible to prolong their life span, further decreasing the cost of using them. In addition, recognizing the aberrations in their performance that warn of the exhaustion of the galvanic cells should permit timely recording and minimize downtime.

  15. Relation between maximum time-varying elastance pressure-volume areas and myocardial oxygen consumption in dogs

    SciTech Connect

    Starling, M.R.; Mancini, G.B.; Montgomery, D.G.; Gross, M.D. )

    1991-01-01

    To establish whether pressure-volume areas (PVAs) calculated using the maximum time-varying elastance (Emax) have a relation with myocardial oxygen consumption (MVO2) that improves on other indexes of myocardial oxygen demand, we studied nine dogs of either sex weighing 19-39 kg, which were instrumented with a micromanometer left ventricular (LV) catheter and a Wilton-Webster coronary sinus flow catheter and had red blood cells tagged with technetium-99m for radionuclide angiography. Hemodynamics, coronary sinus flow determinations, and radionuclide angiograms were obtained under control conditions and during three to five steady-state loading conditions (mean +/- SD, 5.6 +/- 0.7). Isochronal pressure-volume data points from each pressure-volume loop were subjected to linear regression analysis to calculate Emax. The Emax relations, diastolic curves, and systolic portions of each pressure-volume loop were used to obtain calibrated PVAs. The Emax PVA (mm Hg.ml.beat-1.100 g-1) and MVO2 (ml O2.beat-1.100 g-1) values correlated in each animal (r = 0.77 to 0.99). Their slopes averaged (3.48 +/- 1.68) x 10(-5) ml O2.mm Hg-1.ml-1, and their y-axis intercepts averaged 0.07 +/- 0.04 ml O2.beat-1.100 g-1. When the MVO2 relations were compared with Emax PVA, LV systolic pressure-rate product, LV stroke work, and a modification of the LV pressure-work index, the Emax PVA, LV systolic pressure-rate product, and LV pressure-work index had similar relations with MVO2, whereas LV stroke work was a weaker index of MVO2 (p less than 0.05 versus Emax PVA). This occurred because the Emax PVA:MVO2 slopes and y-axis intercepts differed in each dog, which was due to differences in basal LV contractility. The Emax PVA:MVO2 slopes correlated with Emax (r = 0.73, p less than 0.05), and the y-axis intercepts were also weakly related to Emax (r = 0.48, p = 0.19).

  16. Role of macrofauna on benthic oxygen consumption in sandy sediments of a high-energy tidal beach

    NASA Astrophysics Data System (ADS)

    Charbonnier, Céline; Lavesque, Nicolas; Anschutz, Pierre; Bachelet, Guy; Lecroart, Pascal

    2016-06-01

    Sandy beaches exposed to tide and waves are characterized by low abundance and diversity of benthic macrofauna, because of high-energy conditions. This is the reason why there are few studies on benthic communities living in such highly dynamic environments. It has been shown recently that tidal sandy beaches may act as biogeochemical reactors. Marine organic matter that is supplied in the sand during each flood tide is efficiently mineralized through aerobic respiration. In order to quantify the role of macrofauna in the whole beach benthic respiration, we studied the macrofauna and the pore water oxygen content of an exposed sandy beach (Truc Vert, SW of France) during four seasons in 2011. The results showed that macrofauna was characterised by a low number of species of specialized organisms such as the crustaceans Eurydice naylori and Gastrosaccus spp. and the polychaetes Ophelia bicornis and Scolelepis squamata. The distribution and abundance of macrofauna were clearly affected by exposure degree and emersion time. The combined monitoring of benthic macrofauna and pore waters chemistry allowed us to estimate (1) the macrofauna oxygen uptake, calculated with a standard allometric relationship using biomass data, and (2) the total benthic oxygen uptake, calculated from the oxygen deficit measured in pore waters. This revealed that benthic macrofauna respiration represented a variable but low (<10%) contribution to the total benthic oxygen consumption. This suggests that oxygen was mainly consumed by microbial respiration.

  17. Effect of weaning on oxygen consumption and cardiovascular function. A comparison of continuous flow and demand valve systems.

    PubMed

    Ip Yam, P C; Appadurai, I R; Kox, W J

    1994-05-01

    This study compared the continuous positive airways pressure mode of the demand valve system of the Engstrom Erica ventilator with a custom-made continuous flow continuous positive airways pressure system in terms of the oxygen cost of breathing during weaning from mechanical ventilation. Ten consecutive patients in our intensive care unit, with thermodilution pulmonary artery flotation catheters in situ, were studied. Measurements were carried out under steady-state conditions, initially when breathing spontaneously with continuous positive airways pressure via the Erica and then when transition to the continuous flow system was achieved. There were no significant differences between the two methods of providing continuous positive airways pressure in terms of the measured and derived physiological variables studied, with the exception of oxygen consumption. Oxygen consumption with the continuous flow system was significantly less than with the Erica (142.8 (SEM 31.4) ml.min-1.m-2 compared with 165.8 (SEM 30.5) ml.min-1.m-2, p < 0.05). This difference reflects the reduced oxygen cost of breathing when the custom-made continuous flow system was used during weaning.

  18. GREEN CRAB (CARCINUS MAENAS LINNAEUS) CONSUMPTION RATES ON AND PREY PREFERENCES AMONG FOUR BIVALVE PREY SPECIES

    EPA Science Inventory

    The European green crab, Carcinus maenas, is a recent invader to Pacific Northwest (PNW) estuaries with a voracious appetite, especially for bivalves. To assess their potential impact, we estimated green crab consumption rates on four PNW bivalve species, Yaquina oyster (Ostrea ...

  19. Using consumption rate to assess potential predators for biological control of white perch

    USGS Publications Warehouse

    Gosch, N.J.C.; Pope, K.L.

    2011-01-01

    Control of undesirable fishes is important in aquatic systems, and using predation as a tool for biological control is an attractive option to fishery biologists. However, determining the appropriate predators for biological control is critical for success. The objective of this study was to evaluate the utility of consumption rate as an index to determine the most effective predators for biological control of an invasive fish. Consumption rate values were calculated for nine potential predators that prey on white perch Morone americana in Branched Oak and Pawnee reservoirs, Nebraska. The consumption rate index provided a unique and insightful means of determining the potential effectiveness of each predator species in controlling white perch. Cumulative frequency distributions facilitated interpretation by providing a graphical presentation of consumption rates by all individuals within each predator species. Largemouth bass Micropterus salmoides, walleye Sander vitreus and sauger S. canadensis were the most efficient white perch predators in both reservoirs; however, previous attempts to increase biomass of these predators have failed suggesting that successful biological control is unlikely using existing predator species in these Nebraska reservoirs. ?? 2011 ONEMA.

  20. Sexual Preferences in Nutrient Utilization Regulate Oxygen Consumption and Reactive Oxygen Species Generation in Schistosoma mansoni: Potential Implications for Parasite Redox Biology.

    PubMed

    Oliveira, Matheus P; Correa Soares, Juliana B R; Oliveira, Marcus F

    2016-01-01

    Schistosoma mansoni, one of the causative agents of human schistosomiasis, has a unique antioxidant network that is key to parasite survival and a valuable chemotherapeutic target. The ability to detoxify and tolerate reactive oxygen species increases along S. mansoni development in the vertebrate host, suggesting that adult parasites are more exposed to redox challenges than young stages. Indeed, adult parasites are exposed to multiple redox insults generated from blood digestion, activated immune cells, and, potentially, from their own parasitic aerobic metabolism. However, it remains unknown how reactive oxygen species are produced by S. mansoni metabolism, as well as their biological effects on adult worms. Here, we assessed the contribution of nutrients and parasite gender to oxygen utilization pathways, and reactive oxygen species generation in whole unpaired adult S. mansoni worms. We also determined the susceptibilities of both parasite sexes to a pro-oxidant challenge. We observed that glutamine and serum importantly contribute to both respiratory and non-respiratory oxygen utilization in adult worms, but with different proportions among parasite sexes. Analyses of oxygen utilization pathways revealed that respiratory rates were high in male worms, which contrast with high non-respiratory rates in females, regardless nutritional sources. Interestingly, mitochondrial complex I-III activity was higher than complex IV specifically in females. We also observed sexual preferences in substrate utilization to sustain hydrogen peroxide production towards glucose in females, and glutamine in male worms. Despite strikingly high oxidant levels and hydrogen peroxide production rates, female worms were more resistant to a pro-oxidant challenge than male parasites. The data presented here indicate that sexual preferences in nutrient metabolism in adult S. mansoni worms regulate oxygen utilization and reactive oxygen species production, which may differently contribute

  1. Sexual Preferences in Nutrient Utilization Regulate Oxygen Consumption and Reactive Oxygen Species Generation in Schistosoma mansoni: Potential Implications for Parasite Redox Biology

    PubMed Central

    Oliveira, Matheus P.; Correa Soares, Juliana B. R.; Oliveira, Marcus F.

    2016-01-01

    Schistosoma mansoni, one of the causative agents of human schistosomiasis, has a unique antioxidant network that is key to parasite survival and a valuable chemotherapeutic target. The ability to detoxify and tolerate reactive oxygen species increases along S. mansoni development in the vertebrate host, suggesting that adult parasites are more exposed to redox challenges than young stages. Indeed, adult parasites are exposed to multiple redox insults generated from blood digestion, activated immune cells, and, potentially, from their own parasitic aerobic metabolism. However, it remains unknown how reactive oxygen species are produced by S. mansoni metabolism, as well as their biological effects on adult worms. Here, we assessed the contribution of nutrients and parasite gender to oxygen utilization pathways, and reactive oxygen species generation in whole unpaired adult S. mansoni worms. We also determined the susceptibilities of both parasite sexes to a pro-oxidant challenge. We observed that glutamine and serum importantly contribute to both respiratory and non-respiratory oxygen utilization in adult worms, but with different proportions among parasite sexes. Analyses of oxygen utilization pathways revealed that respiratory rates were high in male worms, which contrast with high non-respiratory rates in females, regardless nutritional sources. Interestingly, mitochondrial complex I-III activity was higher than complex IV specifically in females. We also observed sexual preferences in substrate utilization to sustain hydrogen peroxide production towards glucose in females, and glutamine in male worms. Despite strikingly high oxidant levels and hydrogen peroxide production rates, female worms were more resistant to a pro-oxidant challenge than male parasites. The data presented here indicate that sexual preferences in nutrient metabolism in adult S. mansoni worms regulate oxygen utilization and reactive oxygen species production, which may differently contribute

  2. Observed change in peak oxygen consumption after aortic valve replacement and its predictors

    PubMed Central

    Le, Van Doan Tuyet; Jensen, Gunnar Vagn Hagemann; Kjøller-Hansen, Lars

    2016-01-01

    Objective To assess the change in peak oxygen consumption (pVO2) and determine its outcome predictors after aortic valve replacement (AVR) for aortic stenosis (AS). Methods Patients with AS and preserved left ventricular ejection fraction who were referred for single AVR had cardiopulmonary exercise testing prior to and 9 months post-AVR. Predictors of outcome for pVO2 were determined by multivariate linear and logistic regression analyses. A significant change in pVO2 was defined as a relative change that was more than twice the coefficient of repeatability by test–retest (>10%). Results The pre-AVR characteristics of the 37 study patients included the following: median age (range) 72 (46–83) years, aortic valve area index (AVAI) 0.41 (SD 0.11) cm2/m2, mean gradient (MG) 49.1 (SD 15.3) mm Hg and New York Heart Association (NYHA)≥II 27 (73%). Pre-AVR and post-AVR mean pVO2 was 18.5 and 18.4 mL/kg/m2 (87% of the predicted), respectively, but the change from pre-AVR was heterogeneous. The relative change in pVO2 was positively associated with the preoperative MG (β=0.50, p=0.001) and negatively associated with brain natriuretic peptide > upper level of normal according to age and gender (β=−0.40, p=0.009). A relative increase in pVO2 exceeding 10% was found in 9 (24%), predicted by lower pre-AVR AVAI (OR 0.18; 95% CI 0.04 to 0.82, p=0.027) and lower peak O2 pulse (OR 0.94; 95% CI 0.88 to 0.99, p=0.045). Decreases in pVO2 exceeding 10% were found in 11 (30%) and predicted by lower MG (OR 0.93; 95% CI 0.86 to 0.99, p=0.033). Conclusions Change in pVO2 was heterogeneous. Predictors of favourable and unfavourable outcomes for pVO2 were identified. PMID:27252876

  3. In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care

    PubMed Central

    Ciaffoni, Luca; O’Neill, David P.; Couper, John H.; Ritchie, Grant A. D.; Hancock, Gus; Robbins, Peter A.

    2016-01-01

    There are no satisfactory methods for monitoring oxygen consumption in critical care. To address this, we adapted laser absorption spectroscopy to provide measurements of O2, CO2, and water vapor within the airway every 10 ms. The analyzer is integrated within a novel respiratory flow meter that is an order of magnitude more precise than other flow meters. Such precision, coupled with the accurate alignment of gas concentrations with respiratory flow, makes possible the determination of O2 consumption by direct integration over time of the product of O2 concentration and flow. The precision is illustrated by integrating the balance gas (N2 plus Ar) flow and showing that this exchange was near zero. Measured O2 consumption changed by <5% between air and O2 breathing. Clinical capability was illustrated by recording O2 consumption during an aortic aneurysm repair. This device now makes easy, accurate, and noninvasive measurement of O2 consumption for intubated patients in critical care possible. PMID:27532048

  4. In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care.

    PubMed

    Ciaffoni, Luca; O'Neill, David P; Couper, John H; Ritchie, Grant A D; Hancock, Gus; Robbins, Peter A

    2016-08-01

    There are no satisfactory methods for monitoring oxygen consumption in critical care. To address this, we adapted laser absorption spectroscopy to provide measurements of O2, CO2, and water vapor within the airway every 10 ms. The analyzer is integrated within a novel respiratory flow meter that is an order of magnitude more precise than other flow meters. Such precision, coupled with the accurate alignment of gas concentrations with respiratory flow, makes possible the determination of O2 consumption by direct integration over time of the product of O2 concentration and flow. The precision is illustrated by integrating the balance gas (N2 plus Ar) flow and showing that this exchange was near zero. Measured O2 consumption changed by <5% between air and O2 breathing. Clinical capability was illustrated by recording O2 consumption during an aortic aneurysm repair. This device now makes easy, accurate, and noninvasive measurement of O2 consumption for intubated patients in critical care possible. PMID:27532048

  5. Chemical weathering rate, denudation rate, and atmospheric and soil CO2 consumption of Paraná flood basalts in São Paulo State, Brazil

    NASA Astrophysics Data System (ADS)

    da Conceição, Fabiano Tomazini; dos Santos, Carolina Mathias; de Souza Sardinha, Diego; Navarro, Guillermo Rafael Beltran; Godoy, Letícia Hirata

    2015-03-01

    The chemical weathering rate and atmospheric/soil CO2 consumption of Paraná flood basalts in the Preto Stream basin, São Paulo State, Brazil, were evaluated using major elements as natural tracers. Surface and rain water samples were collected in 2006, and analyses were performed to assess pH, temperature, dissolved oxygen (DO), electrical conductivity (EC) and total dissolved solids (TDS), including SO42-, NO3-, PO43 -, HCO3-, Cl-, SiO2, Ca2 +, Mg2 +, Na+ and K+. Fresh rocks and C horizon samples were also collected, taking into account their geological context, abundance and spatial distribution, to analyze major elements and mineralogy. The Preto Stream, downstream from the city of Ribeirão Preto, receives several elements/compounds as a result of anthropogenic activities, with only sulfate yielding negative flux values. The negative flux of SO42 - can be attributed to atmospheric loading that is mainly related to anthropogenic inputs. After corrections were made for atmospheric inputs, the riverine transport of dissolved material was found to be 30 t km- 2 y- 1, with the majority of the dissolved material transported during the summer (wet) months. The chemical weathering rate and atmospheric/soil CO2 consumption were 6 m/Ma and 0.4 · 106 mol km- 2 y- 1, respectively. The chemical weathering rate falls within the lower range of Paraná flood basalt denudation rates between 135 and 35 Ma previously inferred from chronological studies. This comparison suggests that rates of basalt weathering in Brazil's present-day tropical climate differ by at most one order of magnitude from those prevalent at the time of hothouse Earth. The main weathering process is the monosiallitization of anorthoclase, augite, anorthite and microcline. Magnetite is not weathered and thus remains in the soil profile.

  6. Spatial and seasonal variability of sediment oxygen consumption and nutrient fluxes at the sediment water interface in a sub-tropical lagoon (New Caledonia).

    PubMed

    Grenz, C; Denis, L; Pringault, O; Fichez, R

    2010-01-01

    In order to quantify the spatial and seasonal variations of sediment oxygen consumption and nutrient fluxes, we performed a spatial survey in the south west lagoon of New Caledonia during the two major seasons (dry and wet) based on a network of 11 sampling stations. Stations were selected along two barrier reef to land transects representing most types of sediments encountered in the lagoon. Fluxes were measured using ex-situ sediment incubations and compared to sediment characteristics. Sediment oxygen consumption (SOC) varied between 500 and 2000 micromol m(-2)h(-1), depending on season and stations. Nutrient effluxes from sediment were highly variable with highest fluxes measured in muddy sediments near the coast. Inter-sample variability was as high as seasonal differences so that no seasonally driven temperature effect could be observed on benthic nutrient fluxes in our temperature range. Nutrient fluxes, generally directed from the sediment to the water column, varied between -5.0 and 70.0 micromol m(-2)h(-1) for ammonia and between -2.5 and+12.5 micromol m(-2)h(-1) for PO(4) and NO(2+3). SOC and nutrient fluxes were compared to pelagic primary production rates in order to highlight the tight coupling existing between the benthic and pelagic compartments in this shallow tropical lagoon. Under specific occasions of low pelagic productivity, oxygen sediment consumption and related carbon and nutrient fluxes could balance nearly all net primary production in the lagoon. These biogeochemical estimates point to the functional importance of sediment biogeochemistry in the lagoon of New Caledonia.

  7. Can the cerebral metabolic rate of oxygen be estimated with near-infrared spectroscopy?

    NASA Astrophysics Data System (ADS)

    Boas, D. A.; Strangman, G.; Culver, J. P.; Hoge, R. D.; Jasdzewski, G.; Poldrack, R. A.; Rosen, B. R.; Mandeville, J. B.

    2003-08-01

    We have measured the changes in oxy-haemoglobin and deoxy-haemoglobin in the adult human brain during a brief finger tapping exercise using near-infrared spectroscopy (NIRS). The cerebral metabolic rate of oxygen (CMRO2) can be estimated from these NIRS data provided certain model assumptions. The change in CMRO2 is related to changes in the total haemoglobin concentration, deoxy-haemoglobin concentration and blood flow. As NIRS does not provide a measure of dynamic changes in blood flow during brain activation, we relied on a Windkessel model that relates dynamic blood volume and flow changes, which has been used previously for estimating CMRO2 from functional magnetic resonance imaging (fMRI) data. Because of the partial volume effect we are unable to quantify the absolute changes in the local brain haemoglobin concentrations with NIRS and thus are unable to obtain an estimate of the absolute CMRO2 change. An absolute estimate is also confounded by uncertainty in the flow-volume relationship. However, the ratio of the flow change to the CMRO2 change is relatively insensitive to these uncertainties. For the finger tapping task, we estimate a most probable flow-consumption ratio ranging from 1.5 to 3 in agreement with previous findings presented in the literature, although we cannot exclude the possibility that there is no CMRO2 change. The large range in the ratio arises from the large number of model parameters that must be estimated from the data. A more precise estimate of the flow-consumption ratio will require better estimates of the model parameters or flow information, as can be provided by combining NIRS with fMRI.

  8. Organic matter budget in the Southeast Atlantic continental margin close to the Congo Canyon: In situ measurements of sediment oxygen consumption

    NASA Astrophysics Data System (ADS)

    Rabouille, C.; Caprais, J.-C.; Lansard, B.; Crassous, P.; Dedieu, K.; Reyss, J. L.; Khripounoff, A.

    2009-12-01

    A study of organic carbon mineralization from the Congo continental shelf to the abyssal plain through the Congo submarine channel and Angola Margin was undertaken using in situ measurements of sediment oxygen demand as a tracer of benthic carbon recycling. Two measurement techniques were coupled on a single autonomous platform: in situ benthic chambers and microelectrodes, which provided total and diffusive oxygen uptake as well as oxygen microdistributions in porewaters. In addition, sediment trap fluxes, sediment composition (Org-C, Tot-N, CaCO 3, porosity) and radionuclide profiles provided measurements of, respectively input fluxes and burial rate of organic and inorganic compounds. The in situ results show that the oxygen consumption on this margin close to the Congo River is high with values of total oxygen uptake (TOU) of 4±0.6, 3.6±0.5 mmol m -2 d -1 at 1300 and 3100 m depth, respectively, and between 1.9±0.3 and 2.4±0.2 mmol m -2 d -1 at 4000 m depth. Diffusive oxygen uptakes (DOU) were 2.8±1.1, 2.3±0.8, 0.8±0.3 and 1.2±0.1 mmol m -2 d -1, respectively at the same depths. The magnitude of the oxygen demands on the slope is correlated with water depth but is not correlated with the proximity of the submarine channel-levee system, which indicates that cross-slope transport processes are active over the entire margin. Comparison of the vertical flux of organic carbon with its mineralization and burial reveal that this lateral input is very important since the sum of recycling and burial in the sediments is 5-8 times larger than the vertical flux recorded in traps. Transfer of material from the Congo River occurs through turbidity currents channelled in the Congo valley, which are subsequently deposited in the Lobe zone in the Congo fan below 4800 m. Ship board measurements of oxygen profiles indicate large mineralization rates of organic carbon in this zone, which agrees with the high organic carbon content (3%) and the large sedimentation rate (19

  9. Optimization of 2,3-butanediol production by Klebsiella oxytoca through oxygen transfer rate control

    SciTech Connect

    Beronio, P.B. Jr. . Amoco Research Center); Tsao, G.T. . Lab. of Renewable Resources Engineering)

    1993-12-01

    Production of 2,3-butanediol by Klebsiella oxytoca is influenced by the degree of oxygen limitation. During batch culture studies, two phases of growth are observed: energy-coupled growth, during which cell growth and oxygen supply are coupled; and, energy-uncoupled growth, which arises when the degree of oxygen limitation reaches a critical value. Optimal 2,3-butanediol productivity occurs during the energy-coupled growth phase. In this article, a control system which maintains the batch culture at a constant level of oxygen limitation in the energy-coupled growth regime has been designed. Control, which involves feedback control on the oxygen transfer coefficient, is achieved by continually increasing the partial pressure of oxygen in the feed gas, which in turn continually increases the oxygen transfer rate. Control has resulted in a balanced state of growth, a repression of ethanol formation, and an increase in 2,3-butanediol productivity of 18%.

  10. Low energy consumption method for separating gaseous mixtures and in particular for medium purity oxygen production

    DOEpatents

    Jujasz, Albert J.; Burkhart, James A.; Greenberg, Ralph

    1988-01-01

    A method for the separation of gaseous mixtures such as air and for producing medium purity oxygen, comprising compressing the gaseous mixture in a first compressor to about 3.9-4.1 atmospheres pressure, passing said compressed gaseous mixture in heat exchange relationship with sub-ambient temperature gaseous nitrogen, dividing the cooled, pressurized gaseous mixture into first and second streams, introducing the first stream into the high pressure chamber of a double rectification column, separating the gaseous mixture in the rectification column into a liquid oxygen-enriched stream and a gaseous nitrogen stream and supplying the gaseous nitrogen stream for cooling the compressed gaseous mixture, removing the liquid oxygen-enriched stream from the low pressure chamber of the rectification column and pumping the liquid, oxygen-enriched steam to a predetermined pressure, cooling the second stream, condensing the cooled second stream and evaporating the oxygen-enriched stream in an evaporator-condenser, delivering the condensed second stream to the high pressure chamber of the rectification column, and heating the oxygen-enriched stream and blending the oxygen-enriched stream with a compressed blend-air stream to the desired oxygen concentration.

  11. An innovative coupling between column leaching and oxygen consumption tests to assess behavior of contaminated marine dredged sediments.

    PubMed

    Couvidat, Julien; Benzaazoua, Mostafa; Chatain, Vincent; Zhang, Fan; Bouzahzah, Hassan

    2015-07-01

    Contaminated dredged sediments are often considered hazardous wastes, so they have to be adequately managed to avoid leaching of pollutants. The mobility of inorganic contaminants is a major concern. Metal sulfides (mainly framboïdal pyrite, copper, and zinc sulfides) have been investigated in this study as an important reactive metal-bearing phase sensitive to atmospheric oxygen action. An oxygen consumption test (OC-Test) has been adapted to assess the reactivity of dredged sediments when exposed to atmospheric oxygen. An experimental column set-up has been developed allowing the coupling between leaching and oxygen consumption test to investigate the reactivity of the sediment. This reactivity, which consisted of sulfide oxidation, was found to occur for saturation degree between 60 and 90 % and until the 20th testing week, through significant sulfates releases. These latter were assumed to come from sulfide oxidation in the first step of the test, then probably from gypsum dissolution. Confrontation results of OC-Test and leachate quality shows that Cu was well correlated to sulfates releases, which in turn, leads to Ca and Mg dissolution (buffer effect). Cu, and mostly Zn, was associated to organic matter, phyllosilicates, and other minerals through organo-clay complexes. This research confirmed that the OC-Test, originally developed for mine tailings, could be a useful tool in the dredged sediment field which can allow for intrinsic characterization of reactivity of a material suspected to readily reacting with oxygen and for better understanding of geochemical processes that affect pollutants behavior, conversion, and transfer in the environment. PMID:25779112

  12. An innovative coupling between column leaching and oxygen consumption tests to assess behavior of contaminated marine dredged sediments.

    PubMed

    Couvidat, Julien; Benzaazoua, Mostafa; Chatain, Vincent; Zhang, Fan; Bouzahzah, Hassan

    2015-07-01

    Contaminated dredged sediments are often considered hazardous wastes, so they have to be adequately managed to avoid leaching of pollutants. The mobility of inorganic contaminants is a major concern. Metal sulfides (mainly framboïdal pyrite, copper, and zinc sulfides) have been investigated in this study as an important reactive metal-bearing phase sensitive to atmospheric oxygen action. An oxygen consumption test (OC-Test) has been adapted to assess the reactivity of dredged sediments when exposed to atmospheric oxygen. An experimental column set-up has been developed allowing the coupling between leaching and oxygen consumption test to investigate the reactivity of the sediment. This reactivity, which consisted of sulfide oxidation, was found to occur for saturation degree between 60 and 90 % and until the 20th testing week, through significant sulfates releases. These latter were assumed to come from sulfide oxidation in the first step of the test, then probably from gypsum dissolution. Confrontation results of OC-Test and leachate quality shows that Cu was well correlated to sulfates releases, which in turn, leads to Ca and Mg dissolution (buffer effect). Cu, and mostly Zn, was associated to organic matter, phyllosilicates, and other minerals through organo-clay complexes. This research confirmed that the OC-Test, originally developed for mine tailings, could be a useful tool in the dredged sediment field which can allow for intrinsic characterization of reactivity of a material suspected to readily reacting with oxygen and for better understanding of geochemical processes that affect pollutants behavior, conversion, and transfer in the environment.

  13. Influence of simulated microgravity on the maximal oxygen consumption of nontrained and trained rats

    NASA Technical Reports Server (NTRS)

    Woodman, Christopher R.; Monnin, Kimberly A.; Sebastian, Lisa A.; Tipton, Charles M.

    1993-01-01

    The effects of microgravity and endurance training (TR) on maximal O2 consumption was investigated in trained and nontrained (NT) rats subjected to head-down suspension (HDS) by comparing maximal O2 consumption, treadmill run time (RT), and mechanical efficiency (ME) of treadmill running in HDS rats, both NT and TR, and in respective cage controls. It was found that HDS for 28 days was associated with significant reduction in absolute maximal O2 consumption in both TR and NT rats. Relative maximal O2 consumption, however, was significantly reduced in TR but not NT rats. Reductions in RT and ME occurring in both TR and NT rats after 28 days of HDS were similar. The TR rats exhibited greater diuretic, natriuretic, and kaliuretic responses to HDS than the NT rats.

  14. Sensitivity of Hypoxia Predictions for the Northern Gulf of Mexico to Sediment Oxygen Consumption and Model Nesting

    NASA Astrophysics Data System (ADS)

    Fennel, Katja; Hu, Jiatang; Laurent, Arnaud; Marta-Almeida, Martinho; Hetland, Robert

    2014-05-01

    Interannual variations of the hypoxic area that develops every summer over the Texas-Louisiana Shelf are large. The 2008 Action Plan put forth by an alliance of multiple state and federal agencies and tribes calls for a decrease of the hypoxic area through nutrient management in the watershed. Realistic models help build mechanistic understanding of the processes underlying hypoxia formation and are thus indispensable for devising efficient nutrient reduction strategies. Here we present such a model, evaluate its hypoxia predictions against monitoring observations and assess the sensitivity of hypoxia predictions to model resolution, variations in sediment oxygen consumption and choice of physical horizontal boundary conditions. We find that hypoxia predictions on the shelf are very sensitive to the parameterization of sediment oxygen consumption, a result of the fact that hypoxic conditions are restricted to a relatively thin layer above the bottom over most of the shelf. We also show that the strength of vertical stratification is an important predictor of oxygen concentration in bottom waters and that modification of physical horizontal boundary conditions can have a large effect on hypoxia predictions.

  15. Effects of lacidipine on peak oxygen consumption, neurohormones and invasive haemodynamics in patients with mild to moderate chronic heart failure.

    PubMed Central

    de Vries, R. J.; Dunselman, P. H.; Chin Kon Sung, U. G.; van Veldhuisen, D. J.; Corbeij, H. M.; van Gilst, W. H.; Lie, K. I.

    1996-01-01

    OBJECTIVE: To evaluate the efficacy and safety of the second generation dihydropyridine calcium channel blocker lacidipine in patients with heart failure. DESIGN: Placebo controlled, parallel group, double blind study over 8 weeks. SETTING: General community hospital in Breda, The Netherlands. PATIENTS: A random sample was studied of 25 outpatients with symptoms of mild to moderate heart failure, despite treatment with diuretics, digoxin, and angiotensin converting enzyme inhibitors. Their mean age was 65 years, with mean left ventricular ejection fraction of 0.24 and a peak oxygen consumption of 14.4 ml/min/kg. Two patients dropped out on lacidipine, one patient on placebo. INTERVENTION: Treatment with lacidipine 4 mg once daily or placebo for eight weeks. MAIN OUTCOME MEASURE: Cardiopulmonary exercise testing, invasive haemodynamics, and plasma neurohormones. RESULTS: Treatment with lacidipine 4 mg once daily, as compared to placebo treatment, significantly improved peak oxygen consumption (P < 0.02), cardiac index (P < 0.01), and stroke volume (P < 0.03) paralleled by a decrease in systemic vascular resistance (P < 0.03) and arteriovenous oxygen content difference (P < 0.01). Plasma noradrenaline, plasma renin activity, and aldosterone values did not differ between lacidipine and placebo. CONCLUSIONS: This second generation dihydropyridine may be of value as an adjunct to standard treatment in congestive heart failure patients. PMID:8673754

  16. Modeling the fluid-dynamics and oxygen consumption in a porous scaffold stimulated by cyclic squeeze pressure.

    PubMed

    Ferroni, Marco; Giusti, Serena; Nascimento, Diana; Silva, Ana; Boschetti, Federica; Ahluwalia, Arti

    2016-08-01

    The architecture and dynamic physical environment of tissues can be recreated in-vitro by combining 3D porous scaffolds and bioreactors able to apply controlled mechanical stimuli on cells. In such systems, the entity of the stimuli and the distribution of nutrients within the engineered construct depend on the micro-structure of the scaffolds. In this work, we present a new approach for optimizing computational fluid-dynamics (CFD) models for the investigation of fluid-induced forces generated by cyclic squeeze pressure within a porous construct, coupled with oxygen consumption of cardiomyocytes. A 2D axial symmetric macro-scaled model of a squeeze pressure bioreactor chamber was used as starting point for generating time dependent pressure profiles. Subsequently the fluid movement generated by the pressure fields was coupled with a complete 3D micro-scaled model of a porous protein cryogel. Oxygen transport and consumption inside the scaffold was evaluated considering a homogeneous distribution of cardiomyocytes throughout the structure, as confirmed by preliminary cell culture experiments. The results show that a 3D description of the system, coupling a porous geometry and time dependent pressure driven flow with fluid-structure-interaction provides an accurate and meaningful description of the microenvironment in terms of shear stress and oxygen distribution than simple stationary 2D models.

  17. The collaboration of Antoine and Marie-Anne Lavoisier and the first measurements of human oxygen consumption.

    PubMed

    West, John B

    2013-12-01

    Antoine Lavoisier (1743-1794) was one of the most eminent scientists of the late 18th century. He is often referred to as the father of chemistry, in part because of his book Elementary Treatise on Chemistry. In addition he was a major figure in respiratory physiology, being the first person to recognize the true nature of oxygen, elucidating the similarities between respiration and combustion, and making the first measurements of human oxygen consumption under various conditions. Less well known are the contributions made by his wife, Marie-Anne Lavoisier. However, she was responsible for drawings of the experiments on oxygen consumption when the French revolution was imminent. These are of great interest because written descriptions are not available. Possible interpretations of the experiments are given here. In addition, her translations from English to French of papers by Priestley and others were critical in Lavoisier's demolition of the erroneous phlogiston theory. She also provided the engravings for her husband's textbook, thus documenting the extensive new equipment that he developed. In addition she undertook editorial work, for example in preparing his posthumous memoirs. The scientific collaboration of this husband-wife team is perhaps unique among the giants of respiratory physiology. PMID:24097559

  18. The collaboration of Antoine and Marie-Anne Lavoisier and the first measurements of human oxygen consumption.

    PubMed

    West, John B

    2013-12-01

    Antoine Lavoisier (1743-1794) was one of the most eminent scientists of the late 18th century. He is often referred to as the father of chemistry, in part because of his book Elementary Treatise on Chemistry. In addition he was a major figure in respiratory physiology, being the first person to recognize the true nature of oxygen, elucidating the similarities between respiration and combustion, and making the first measurements of human oxygen consumption under various conditions. Less well known are the contributions made by his wife, Marie-Anne Lavoisier. However, she was responsible for drawings of the experiments on oxygen consumption when the French revolution was imminent. These are of great interest because written descriptions are not available. Possible interpretations of the experiments are given here. In addition, her translations from English to French of papers by Priestley and others were critical in Lavoisier's demolition of the erroneous phlogiston theory. She also provided the engravings for her husband's textbook, thus documenting the extensive new equipment that he developed. In addition she undertook editorial work, for example in preparing his posthumous memoirs. The scientific collaboration of this husband-wife team is perhaps unique among the giants of respiratory physiology.

  19. Alterations in the rate of binge ethanol consumption: implications for preclinical studies in mice.

    PubMed

    Linsenbardt, David N; Boehm, Stephen L

    2014-09-01

    The rate at which alcohol (ethanol) is consumed has direct impact on its behavioral and subjective effects. For this reason, alterations in the pattern of ethanol consumption as a function of drinking history might be critical to the development and maintenance of alcoholism. Furthermore, because pharmacological interventions aimed at disrupting the motivation to consume ethanol are dependent on the brain/plasma concentrations present when an individual is most likely to engage in consumption of this substance, characterizing temporal drinking patterns might be useful to determine the timing of such treatments. The primary goal of the present study was to evaluate alterations in the timecourse of daily binge (drinking-in-the-dark; DID) ethanol consumption. We gave 14 daily 2 hour DID ethanol or water access sessions to male C57BL/6J (B6) mice using a state of the art volumetric drinking monitoring device. We then, primarily as a proof-of-principle, used the GABAB allosteric modulator GS39783 (GS) to determine how this compound influenced the timecourse of binge-like ethanol intake. The rate of ethanol consumption increased dramatically over sessions with the majority occurring in the first few minutes of the final session. Additionally, ethanol consumption occurring immediately following access was almost completely abolished in mice pre-treated with GS; an effect which was ethanol-specific only at this early time interval. These data characterize progressive alterations in the rate of ethanol intake using the DID model and suggest that careful consideration of prior ethanol history and timing of drug administration are warranted when interpreting results of pre-clinical drug administration studies.

  20. Validation of an equation for estimating maximal oxygen consumption of nonexpert adult swimmers

    PubMed Central

    da Costa, Adalberto Veronese; Costa, Manoel da Cunha; de Oliveira, Saulo Fernandes Melo; de Albuquerque, Fabíola Lima; de Sá Pereira Guimarães, Fernando José; Barbosa, Tiago Manuel

    2013-01-01

    Objective To validate an equation to estimate the maximal oxygen consumption (VO2max) of nonexpert adult swimmers. Methods Participants were 22 nonexpert swimmers, male, aged between 18 and 30 years (age: 23.1 ± 3:59 years; body mass: 73.6 ± 7:39 kg; height 176.6 ± 5.53 cm; and body fat percentage: 15.9% ± 4.39%), divided into two subgroups: G1 – eleven swimmers for the VO2max oximetry and modeling of the equation; and G2 – eleven swimmers for application of the equation modeled on G1 and verification of their validation. The test used was the adapted Progressive Swim Test, in which there occurs an increase in the intensity of the swim every two laps. For normality and homogeneity of data, Shapiro-Wilk and Levene tests were used, the descriptive values of the average and standard deviation. The statistical steps were: (1) reliability of the Progressive Swim Test – through the paired t-test, intraclass correlation coefficient (ICC), and the Pearson linear correlation (R) relative to the reproducibility, the coefficient of variation (CV), and standard error measurement (SEM) for the absolute reproducibility; (2) in the model equation to estimate VO2max, a relative VO2 was established, and a stepwise multiple regression model was performed with G1 – so the variables used were analysis of variance regression (AR), coefficient of determination (R2), adjusted coefficient of determination (R2a), standard error of estimate (SEE), and Durbin–Watson (DW); (3) validation of the equation – the results were presented in graphs, where direct (G1) and estimated (G2) VO2max were compared using independent t-test, linear regression (stressing the correlation between groups), and Bland–Altman (the bias agreement of the results). All considered a statistical significance level of P < 0.05. Results On the trustworthiness of the Progressive Swim Test adapted presented as high as observed (R and ICC > 0.80, CV < 10%, and SEM < 2%). In the equation model, VO2max has

  1. Elevated blood Hg at recommended seafood consumption rates in adult seafood consumers.

    PubMed

    Karimi, Roxanne; Silbernagel, Susan; Fisher, Nicholas S; Meliker, Jaymie R

    2014-09-01

    Mercury (Hg) exposure from seafood continues to be a public health concern due to health effects from elevated exposure, increasing worldwide seafood consumption, and continued Hg inputs into the environment. Elevated Hg exposure can occur in populations with specialized diets of sport-caught freshwater fish. However, we need a better understanding of Hg exposure from seafood, the most common exposure source, and from specific seafood types. We examined Hg exposure in avid seafood consumers, and the seafood items and consumption frequency that confer the largest Hg exposure. Adult, avid seafood consumers, in Long Island, NY, USA, with blood total Hg concentrations predicted to exceed the USEPA reference concentration that is considered safe (5.8 μg L(-1)), were eligible for the study; 75% of self-reported avid seafood consumers were eligible to participate. We measured blood total Hg concentrations and seafood consumption in 285 participants. We examined relationships between Hg and seafood consumption using multiple linear regression. Seafood consumption rate for our population (14.4 kg yr(-1)) was >2 times that estimated for the U.S. (6.8 kg yr(-1)), and lower than the worldwide estimate (18.4 kg yr(-1)). Mean blood Hg concentration was 4.4 times the national average, and 42% of participants had Hg concentrations exceeding 5.8 μg L(-1). Elevated Hg exposures occurred at all seafood consumption frequencies, including the recommended frequency of 2 meals per week. Blood Hg concentrations were positively associated with weekly tuna steak or sushi intake (β=6.30 change in blood Hg, μg L(-1)) and monthly (β=2.54) or weekly (β=9.47) swordfish, shark or marlin intake. Our findings show that seafood consumers in this population have elevated Hg exposures even at relatively low seafood consumption rates that are at or below current dietary recommendations. Further study should examine health risks and benefits of avid seafood consumption, and consider modifying

  2. Seasonal variation in thermal tolerance, oxygen consumption, antioxidative enzymes and non-specific immune indices of Indian hill trout, Barilius bendelisis (Hamilton, 1807) from central Himalaya, India.

    PubMed

    Sharma, Neeraj Kumar; Akhtar, M S; Pandey, Nityanand; Singh, Ravindra; Singh, Atul Kumar

    2015-08-01

    We studied the season dependent thermal tolerance, oxygen consumption, respiratory burst response and antioxidative enzyme activities in juveniles of Barilius bendelisis. The critical thermal maximum (CTmax), lethal thermal maximum (LTmax), critical thermal minimum (CTmin) and lethal thermal minimum (LTmin) were significantly different at five different seasons viz. winter (10.64°C), spring (16.25°C), summer (22.11°C), rainy (20.87°C) and autumn (17.77°C). The highest CTmax was registered in summer (36.02°C), and lowest CTmin was recorded during winter (2.77°C). Water temperature, dissolved oxygen and pH were strongly related to CTmax, LTmax, CTmin and LTmin suggesting seasonal acclimatization of B. bendelisis. The thermal tolerance polygon area of the B. bendelisis juveniles within the range of seasonal temperature (10.64-22.11°C) was calculated as 470.92°C(2). Oxygen consumption rate was significantly different (p<0.05) between seasons with maximum value during summer (57.66mgO2/kg/h) and lowest in winter (32.60mgO2/kg/h). Total white blood cell count including neutrophil and monocytes also showed significant difference (p<0.05) between seasons with maximum value during summer and minimum number in winter and were found correlated to temperature, dissolved oxygen, pH and respiratory burst activity. Respiratory burst activity of blood phagocytes significantly differed (p<0.05) among seasons with higher value during summer (0.163 OD540nm) and minimum in winter season (0.054 OD540nm). The activity of superoxide dismutase, catalase and glutathione-s-transferase both in liver and gill, also varied significantly (p<0.05) during different seasons. Overall results of this study suggest that multiple environmental factors play a role in seasonal acclimation in B. bendelisis, which modulate the thermal tolerance, oxygen consumption, respiratory burst activity and status of anti-oxidative potential in wild environment.

  3. Growth, oxygen consumption and activity of juvenile turbot ( scophthalmus maximus L.) reared under different temperatures and photoperiods

    NASA Astrophysics Data System (ADS)

    Imsland, Albert K.; Folkvord, A.; Stefansson, S. O.

    Juvenile turbot (5-125 g) were reared under two experimental temperatures: 10°C and 16°C, and three experimental photoperiods: LDN (natural photoperiod), LD 16:8 (16 h light: 8 h darkness), LD24:0 (continuous light), to study effects of temperature and photoperiod on growth, activity and oxygen consumption. Growth was strongly affected by temperature and was higher at 16°C than at 10°C. Continuous light had a growth-promoting effect at 10°C from mid-December to late March, while at 16°C this effect was restricted to December and January. A seasonal change in the condition index was found. The groups reared in continuous light had higher condition indices in winter. The experimental groups held at 16°C had higher O 2 consumption than those at 10°C. The LD24:0 groups invariably had a higher overall O 2 consumption than did the LDN and LD16:8 groups, the differences being caused by reduced O 2 consumption in the latter groups during darkness. The LD24:0 groups displayed higher activity than the LDN groups, in which activity was very low at night.

  4. Simultaneous and noninvasive imaging of cerebral oxygen metabolic rate, blood flow and oxygen extraction fraction in stroke mice.

    PubMed

    Zhu, Xiao-Hong; Chen, James M; Tu, Tsang-Wei; Chen, Wei; Song, Sheng-Kwei

    2013-01-01

    Many brain diseases have been linked to abnormal oxygen metabolism and blood perfusion; nevertheless, there is still a lack of robust diagnostic tools for directly imaging cerebral metabolic rate of oxygen (CMRO(2)) and cerebral blood flow (CBF), as well as the oxygen extraction fraction (OEF) that reflects the balance between CMRO(2) and CBF. This study employed the recently developed in vivo (17)O MR spectroscopic imaging to simultaneously assess CMRO(2), CBF and OEF in the brain using a preclinical middle cerebral arterial occlusion mouse model with a brief inhalation of (17)O-labeled oxygen gas. The results demonstrated high sensitivity and reliability of the noninvasive (17)O-MR approach for rapidly imaging CMRO(2), CBF and OEF abnormalities in the ischemic cortex of the MCAO mouse brain. It was found that in the ischemic brain regions both CMRO(2) and CBF were substantially lower than that of intact brain regions, even for the mildly damaged brain regions that were unable to be clearly identified by the conventional MRI. In contrast, OEF was higher in the MCAO affected brain regions. This study demonstrates a promising (17)O MRI technique for imaging abnormal oxygen metabolism and perfusion in the diseased brain regions. This (17)O MRI technique is advantageous because of its robustness, simplicity, noninvasiveness and reliability: features that are essential to potentially translate it to human patients for early diagnosis and monitoring of treatment efficacy.

  5. Monitoring the variations of the oxygen transfer rate in a full scale membrane bioreactor using daily mass balances.

    PubMed

    Racault, Y; Stricker, A-E; Husson, A; Gillot, S

    2011-01-01

    Oxygen transfer in biological wastewater treatment processes with high sludge concentration, such as membrane bioreactor (MBR), is an important issue. The variation of alpha-factor versus mixed liquor suspended solids (MLSS) concentration was investigated in a full scale MBR plant under process conditions, using mass balances. Exhaustive data from the Supervisory Control And Data Acquisition (SCADA) and from additional online sensors (COD, DO, MLSS) were used to calculate the daily oxygen consumption (OC) using a non-steady state mass balance for COD and total N on a 24-h basis. To close the oxygen balance, OC has to match the total oxygen transfer rate (OTRtot) of the system, which is provided by fine bubble (FB) diffusers in the aeration tank and coarse bubbles (CB) in separate membrane tanks. First assessing OTR(CB) then closing the balance OC = OTRtot allowed to calculate OTR(FB) and to fit an exponential relationship between OTR(FB) and MLSS. A comparison of the alpha-factor obtained by this balance method and by direct measurements with the off-gas method on the same plant is presented and discussed. PMID:22049761

  6. A numerical investigation of oxygen concentration dependence on biodegradation rate laws in vapor intrusion.

    PubMed

    Yao, Yijun; Shen, Rui; Pennel, Kelly G; Suuberg, Eric M

    2013-12-01

    In subsurface vapor intrusion, aerobic biodegradation has been considered as a major environmental factor that determines the soil gas concentration attenuation factors for contaminants such as petroleum hydrocarbons. The site investigation has shown that oxygen can play an important role in this biodegradation rate, and this paper explores the influence of oxygen concentration on biodegradation reactions included in vapor intrusion (VI) models. Two different three dimensional (3-D) numerical models of vapor intrusion were explored for their sensitivity to the form of the biodegradation rate law. A second order biodegradation rate law, explicitly including oxygen concentration dependence, was introduced into one model. The results indicate that the aerobic/anoxic interface depth is determined by the ratio of contaminant source vapor to atmospheric oxygen concentration, and that the contaminant concentration profile in the aerobic zone was significantly influenced by the choice of rate law.

  7. A numerical investigation of oxygen concentration dependence on biodegradation rate laws in vapor intrusion.

    PubMed

    Yao, Yijun; Shen, Rui; Pennel, Kelly G; Suuberg, Eric M

    2013-12-01

    In subsurface vapor intrusion, aerobic biodegradation has been considered as a major environmental factor that determines the soil gas concentration attenuation factors for contaminants such as petroleum hydrocarbons. The site investigation has shown that oxygen can play an important role in this biodegradation rate, and this paper explores the influence of oxygen concentration on biodegradation reactions included in vapor intrusion (VI) models. Two different three dimensional (3-D) numerical models of vapor intrusion were explored for their sensitivity to the form of the biodegradation rate law. A second order biodegradation rate law, explicitly including oxygen concentration dependence, was introduced into one model. The results indicate that the aerobic/anoxic interface depth is determined by the ratio of contaminant source vapor to atmospheric oxygen concentration, and that the contaminant concentration profile in the aerobic zone was significantly influenced by the choice of rate law. PMID:24197079

  8. Rate of reaction between molecular hydrogen and molecular oxygen

    NASA Technical Reports Server (NTRS)

    Brokaw, R. S.

    1973-01-01

    The shock tube data of Jachimowski and Houghton were rigorously analyzed to obtain rate constants for the candidate initiation reactions H2 + O2 yields H + HO2, H2 + O2 yields H2O + O, and H2 + O2 yields OH + OH. Reaction (01) is probably not the initiation process because the activation energy obtained is less than the endothermicity and because the derived rates greatly exceed values inferred in the literature from the reverse of reaction (01). Reactions (02) and (03) remain as possibilities, with reaction (02) slightly favored on the basis of steric and statistical considerations. The solution of the differential equations is presented in detail to show how the kinetics of other ignition systems may be solved.

  9. Oxygen Ion Heat Rate within Alfvenic Turbulence in the Cusp

    NASA Technical Reports Server (NTRS)

    Coffey, Victoria N.; Singh, Nagendra; Chandler, Michael O.

    2009-01-01

    The role that the cleft/cusp has in ionosphere-magnetosphere coupling makes it a dynamic and important region. It is directly exposed to the solar wind, making it possible for the entry of electromagnetic energy and precipitating electrons and ions from dayside reconnection and other dayside events. It is also a significant source of ionospheric plasma, contributing largely to the mass loading of the magnetosphere with large fluxes of outflowing ions. Crossing the cusp/cleft near 5100 km, the Polar instruments observe the common correlation of downward Poynting flux, ion energization, soft electron precipitation, broadband extremely low-frequency (BB-ELF) emissions, and density depletions. The dominant power in the BB-ELF emissions is now identified to be from spatially broad, low frequency Alfv nic structures. For a cusp crossing, we determine using the Electric Field Investigation (EFI), that the electric and magnetic field fluctuations are Alfv nic and the electric field gradients satisfy the inequality for stochastic acceleration. With all the Polar 1996 horizontal crossings of the cusp, we determine the O+ heating rate using the Thermal Ion Dynamics Experiment (TIDE) and Plasma Wave Investigation (PWI). We then compare this heating rate to other heating rates assuming the electric field gradient criteria exceeds the limit for stochastic acceleration for the remaining crossings. The comparison suggests that a stochastic acceleration mechanism is operational and the heating is controlled by the transverse spatial scale of the Alfvenic waves.

  10. In-situ sediment oxygen demand rates in Hammonton Creek, Hammonton, New Jersey, and Crosswicks Creek, near New Egypt, New Jersey, August-October 2009

    USGS Publications Warehouse

    Wilson, Timothy P.

    2014-01-01

    Sediment oxygen demand rates were measured in Hammonton Creek, Hammonton, New Jersey, and Crosswicks Creek, near New Egypt, New Jersey, during August through October 2009. These rates were measured as part of an ongoing water-quality monitoring program being conducted in cooperation with the New Jersey Department of Environmental Protection. Oxygen depletion rates were measured using in-situ test chambers and a non-consumptive optical electrode sensing technique for measuring dissolved oxygen concentrations. Sediment oxygen demand rates were calculated on the basis of these field measured oxygen depletion rates and the temperature of the stream water at each site. Hammonton Creek originates at an impoundment, then flows through pine forest and agricultural fields, and receives discharge from a sewage-treatment plant. The streambed is predominantly sand and fine gravel with isolated pockets of organic-rich detritus. Sediment oxygen demand rates were calculated at four sites on Hammonton Creek and were found to range from -0.3 to -5.1 grams per square meter per day (g/m2/d), adjusted to 20 degrees Celsius. When deployed in pairs, the chambers produced similar values, indicating that the method was working as expected and yielding reproducible results. At one site where the chamber was deployed for more than 12 hours, dissolved oxygen was consumed linearly over the entire test period. Crosswicks Creek originates in a marshy woodland area and then flows through woodlots and pastures. The streambed is predominantly silt and clay with some bedrock exposures. Oxygen depletion rates were measured at three sites within the main channel of the creek, and the calculated sediment oxygen demand rates ranged from -0.33 to -2.5 g/m2/d, adjusted to 20 degrees Celsius. At one of these sites sediment oxygen demand was measured in both a center channel flowing area of a pond in the stream and in a stagnant non-flowing area along the shore of the pond where organic-rich bottom

  11. Tobacco use, Alcohol Consumption and Self-rated Oral Health among Nigerian Prison Officials

    PubMed Central

    Azodo, Clement Chinedu; Omili, Michael

    2014-01-01

    Background: The oral health condition and lifestyle in term of tobacco use and alcohol consumption of custodian of prisons have been left unstudied. The purpose of this study was to determine the prevalence of tobacco use, alcohol consumption and self-rated oral health among Nigerian prison officials. Methods: This cross-sectional study was conducted among prison officials working in Abuja, Nassarawa and Kano prison yards between March and June 2011 using 28-item self-administered questionnaire as a tool of data collection. The questionnaire elicited information on demography, self-rated oral health, oral health behaviors, oral health conditions, tobacco use, pattern and quit attempts, alcohol consumption, type and pattern. Results: The participants were aged between 20 and 51 years, with a mean age of 32.25 ± 6.13 years. The majority of the participants were males (66.4%), Christians (76.7%), junior officials (78.1%) and of Northern origin (50.7%). A total of 50 (34.2%) of the participants indicated that they were tobacco users and 39 (78.0%) indulged in cigarette smoking only. Of the study participants, 67 (45.9%) indicated they consume alcohol, beer majorly and gin rarely with 23 (34.3%) consuming it excessively. The dominant tooth cleaning device utilized by the participants was toothbrush and toothpaste, and 65 (44.5%) had visited the dentists with the majority of the visit done >5 years ago. About one-third 57 (39.0%) reported experiencing one or more forms of oral disease. However, it was only 17 (11.6%) of them that rated their oral health poor/fair, and the determinants of self-rated oral health were age, rank, and oral health condition. Conclusions: Data from this survey revealed that the majority of the participants rated their oral health as good/excellent. The prevalence of tobacco use and alcohol consumption among prison officials was higher than reported values among the general population in Nigeria. This indicates that more surveillance and

  12. The oxygen transfer rate influences the molecular mass of the alginate produced by Azotobacter vinelandii.

    PubMed

    Díaz-Barrera, A; Peña, C; Galindo, E

    2007-09-01

    The influence of oxygen transfer rate (OTR) on the molecular mass of alginate was studied. In batch cultures without dissolved oxygen tension (DOT) control and at different agitation rates, the DOT was nearly zero and the OTR was constant during biomass growth, hence the cultures were oxygen-limited. The OTR reached different maximum levels (OTR(max)) and enabled to establish various relative respiration rates. Overall, the findings showed that OTR influences alginate molecular mass. The mean molecular mass (MMM) of the alginate increased as OTR(max) decreased. The molecular mass obtained at 3.0 mmol l(-1) h(-1) was 7.0 times higher (1,560 kDa) than at 9.0 mmol l(-1) h(-1) (220 kDa). An increase in molecular mass can be a bacterial response to adverse nutritional conditions such as oxygen limitation.

  13. A nondestructive technique to determine the rate of oxygen permeation into solid dosage forms.

    PubMed

    Felton, L A; Timmins, G S

    2006-02-01

    The current study investigated the use of electron paramagnetic resonance (EPR) spectroscopy as a nondestructive method to quantify the partial pressure of oxygen (PO2) in tablets and hard shell capsules. Lithium phthalocyanine crystals (LiPC) were placed inside the dosage forms. The peak-to-peak linewidth of the first derivative of the LiPC EPR spectra was measured and, by calibration tables, the oxygen partial pressure, pO2, within the dosage form was determined. The intra-dosage form pO2 was followed as a function of time after changing the exterior gas stream composition. Results showed initial oxygen concentrations comparable to atmospheric levels in all tablets and capsules investigated. Oxygen rapidly permeated into unsealed gelatin and cellulosic hard shell capsules. Banding at the cap/body joint significantly reduced the oxygen permeation rate. Oxygen also rapidly permeated into tablet compacts, regardless of the compressional force used during tableting, while application of a polymeric film significantly decreased the rate of oxygen permeation. This EPR technique was shown to be a suitable nondestructive method to study oxygen permeation kinetics in solid dosage forms.

  14. Cold-induced vasodilatation of finger and maximal oxygen consumption of young female athletes born in Hokkaido

    NASA Astrophysics Data System (ADS)

    Moriya, Kiyoshi; Nakagawa, Koya

    1990-03-01

    To determine whether there is a direct correlation between endurance capacity and cold tolerance, maximal oxygen consumption (VO2max), and cold-induced vasodilatation (CIVD), we measured these factors in 14 young female athletes born in Hokkaido, Japan's northernmost island. We determined the VO2max by a standard incremental test on a cycle ergometer and measured the oxygen consumption (VO2) by means of the Douglas-bag method. We determined the CIVD reaction by measuring the skin temperature of the left middle finger during immersion in cold water at 0°C for 20 min. The athletes showed significant positive correlations between VO2max, expressed as l/min, and CIVD as well as other peripheral cold tolerance indexes (resistance index against frostbite and CIVD index). The body weight VO2max (VO2max/kg body weight) failed to correlate significantly with either the CIVD or with other cold tolerance indexes. These results suggest that CIVD in females may depend on factors other than those determined in this study, in addition to the functional spread of the vascular beds in peripheral tissues, including striated muscle; it is known that the size and the vascular bed in this tissue are affected by exercise training and that this results in the elevation of VO2max and VO2max/kg body weight.

  15. Daily changes in oxygen saturation and pulse rate associated with particulate air pollution and barometric pressure.

    PubMed

    Dockery, D W; Pope, C A; Kanner, R E; Martin Villegas, G; Schwartz, J

    1999-01-01

    Epidemiologic studies have linked fine particulate air pollution with increases in morbidity and mortality rates from cardiopulmonary complications. Although the underlying biologic mechanisms responsible for this increase remain largely unknown, potential pathways include transient declines in blood oxygenation and changes in pulse rate following exposures to particulate air pollution episodes. This study evaluated potential associations between daily measures of respirable particulate matter (PM) with pulse rate and oxygen saturation of the blood. Pulse rate and oxygen saturation (Spo2) using pulse oximetry were measured daily in 90 elderly subjects living near air pollution monitors during the winter of 1995-96 in Utah Valley. We also evaluated potential associations of oxygen saturation and pulse rate with barometric pressure. Small but statistically significant positive associations between day-to-day changes in Spo2 and barometric pressure were observed. Pulse rate was inversely associated with barometric pressure. Exposure to particulate pollution was not significantly associated with Spo2 except in male participants 80 years of age or older. Increased daily pulse rate, as well as the odds of having a pulse rate 5 or 10 beats per minute (bpm) above normal (normal is defined as the individual's mean pulse rate throughout the study period), were significantly associated with exposure to particulate pollution on the previous 1 to 5 days. The medical or biologic relevance of these increases in pulse rate following exposure to particulate air pollution requires further study.

  16. Daily changes in oxygen saturation and pulse rate associated with particulate air pollution and barometric pressure.

    PubMed

    Dockery, D W; Pope, C A; Kanner, R E; Martin Villegas, G; Schwartz, J

    1999-01-01

    Epidemiologic studies have linked fine particulate air pollution with increases in morbidity and mortality rates from cardiopulmonary complications. Although the underlying biologic mechanisms responsible for this increase remain largely unknown, potential pathways include transient declines in blood oxygenation and changes in pulse rate following exposures to particulate air pollution episodes. This study evaluated potential associations between daily measures of respirable particulate matter (PM) with pulse rate and oxygen saturation of the blood. Pulse rate and oxygen saturation (Spo2) using pulse oximetry were measured daily in 90 elderly subjects living near air pollution monitors during the winter of 1995-96 in Utah Valley. We also evaluated potential associations of oxygen saturation and pulse rate with barometric pressure. Small but statistically significant positive associations between day-to-day changes in Spo2 and barometric pressure were observed. Pulse rate was inversely associated with barometric pressure. Exposure to particulate pollution was not significantly associated with Spo2 except in male participants 80 years of age or older. Increased daily pulse rate, as well as the odds of having a pulse rate 5 or 10 beats per minute (bpm) above normal (normal is defined as the individual's mean pulse rate throughout the study period), were significantly associated with exposure to particulate pollution on the previous 1 to 5 days. The medical or biologic relevance of these increases in pulse rate following exposure to particulate air pollution requires further study. PMID:10192116

  17. Fish consumption behavior and rates in native and non-native people in Saudi Arabia

    PubMed Central

    Burger, Joanna; Gochfeld, Michael; Batang, Zenon; Alikunhi, Nabeel; Al-Jahdali, Ramzi; Al-Jebreen, Dalal; Aziz, Mohammed A. M.; Al-Suwailem, Abdulaziz

    2015-01-01

    Fish are a healthy source of protein and nutrients, but contaminants in fish may provide health risks. Determining the risk from contaminants in fish requires site-specific information on consumption patterns. We examine consumption rates for resident and expatriates in the Jeddah region of Saudi Arabia, by species of fish and fishing location. For Saudis, 3.7 % of males and 4.3 % of females do not eat fish; for expatriates, the percent not eating fish is 6.6 % and 6.1 % respectively. Most people eat fish at home (over 90 %), and many eat fish at restaurants (65 % and 48 %, respectively for Saudis and expatriates). Fish eaten at home comes from local fish markets, followed by supermarkets. Saudis included fish in their diets at an average of 1.4±1.2 meals/week at home and 0.8±0.7 meals/week at restaurants, while expats ate 2.0±1.7 meals/week at home and 1.1±1.1 meals/week in restaurants. Overall, Saudis ate 2.2 fish meals/week, while expats ate 3.1 meals/week. Grouper (Epinephelus and Cephalopholis) were eaten by 72% and 60% respectively. Plectropomus pessuliferus was the second favorite for both groups and Hipposcarus harid and Lethrinus lentjan were in 3rd and 4th place in terms of consumption. Average meal size was 68 g for Saudis and 128 g for expatriates. These data can be used by health professionals, risk assessors, and environmental regulators to examine potential risk from contaminants in fish, and to compare consumption rates with other sites. PMID:24926920

  18. Fish consumption behavior and rates in native and non-native people in Saudi Arabia.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Batang, Zenon; Alikunhi, Nabeel; Al-Jahdali, Ramzi; Al-Jebreen, Dalal; Aziz, Mohammed A M; Al-Suwailem, Abdulaziz

    2014-08-01

    Fish are a healthy source of protein and nutrients, but contaminants in fish may provide health risks. Determining the risk from contaminants in fish requires site-specific information on consumption patterns. We examine consumption rates for resident and expatriates in the Jeddah region of Saudi Arabia, by species of fish and fishing location. For Saudis, 3.7% of males and 4.3% of females do not eat fish; for expatriates, the percent not eating fish is 6.6% and 6.1% respectively. Most people eat fish at home (over 90%), and many eat fish at restaurants (65% and 48%, respectively for Saudis and expatriates). Fish eaten at home comes from local fish markets, followed by supermarkets. Saudis included fish in their diets at an average of 1.4 ± 1.2 meals/week at home and 0.8 ± 0.7 meals/week at restaurants, while expats ate 2.0 ± 1.7 meals/week at home and 1.1 ± 1.1 meals/week in restaurants. Overall, Saudis ate 2.2 fish meals/week, while expats ate 3.1 meals/week. Grouper (Epinephelus and Cephalopholis) were eaten by 72% and 60% respectively. Plectropomus pessuliferus was the second favorite for both groups and Hipposcarus harid and Lethrinus lentjan were in 3rd and 4th place in terms of consumption. Average meal size was 68 g for Saudis and 128 g for expatriates. These data can be used by health professionals, risk assessors, and environmental regulators to examine potential risk from contaminants in fish, and to compare consumption rates with other sites.

  19. Fish consumption behavior and rates in native and non-native people in Saudi Arabia.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Batang, Zenon; Alikunhi, Nabeel; Al-Jahdali, Ramzi; Al-Jebreen, Dalal; Aziz, Mohammed A M; Al-Suwailem, Abdulaziz

    2014-08-01

    Fish are a healthy source of protein and nutrients, but contaminants in fish may provide health risks. Determining the risk from contaminants in fish requires site-specific information on consumption patterns. We examine consumption rates for resident and expatriates in the Jeddah region of Saudi Arabia, by species of fish and fishing location. For Saudis, 3.7% of males and 4.3% of females do not eat fish; for expatriates, the percent not eating fish is 6.6% and 6.1% respectively. Most people eat fish at home (over 90%), and many eat fish at restaurants (65% and 48%, respectively for Saudis and expatriates). Fish eaten at home comes from local fish markets, followed by supermarkets. Saudis included fish in their diets at an average of 1.4 ± 1.2 meals/week at home and 0.8 ± 0.7 meals/week at restaurants, while expats ate 2.0 ± 1.7 meals/week at home and 1.1 ± 1.1 meals/week in restaurants. Overall, Saudis ate 2.2 fish meals/week, while expats ate 3.1 meals/week. Grouper (Epinephelus and Cephalopholis) were eaten by 72% and 60% respectively. Plectropomus pessuliferus was the second favorite for both groups and Hipposcarus harid and Lethrinus lentjan were in 3rd and 4th place in terms of consumption. Average meal size was 68 g for Saudis and 128 g for expatriates. These data can be used by health professionals, risk assessors, and environmental regulators to examine potential risk from contaminants in fish, and to compare consumption rates with other sites. PMID:24926920

  20. Is beetroot juice more effective than sodium nitrate? The effects of equimolar nitrate dosages of nitrate-rich beetroot juice and sodium nitrate on oxygen consumption during exercise.

    PubMed

    Flueck, Joelle Leonie; Bogdanova, Anna; Mettler, Samuel; Perret, Claudio

    2016-04-01

    Dietary nitrate has been reported to lower oxygen consumption in moderate- and severe-intensity exercise. To date, it is unproven that sodium nitrate (NaNO3(-); NIT) and nitrate-rich beetroot juice (BR) have the same effects on oxygen consumption, blood pressure, and plasma nitrate and nitrite concentrations or not. The aim of this study was to compare the effects of different dosages of NIT and BR on oxygen consumption in male athletes. Twelve healthy, well-trained men (median [minimum; maximum]; peak oxygen consumption: 59.4 mL·min(-1)·kg(-1) [40.5; 67.0]) performed 7 trials on different days, ingesting different nitrate dosages and placebo (PLC). Dosages were 3, 6, and 12 mmol nitrate as concentrated BR or NIT dissolved in plain water. Plasma nitrate and nitrite concentrations were measured before, 3 h after ingestion, and postexercise. Participants cycled for 5 min at moderate intensity and further 8 min at severe intensity. End-exercise oxygen consumption at moderate intensity was not significantly different between the 7 trials (p = 0.08). At severe-intensity exercise, end-exercise oxygen consumption was ~4% lower in the 6-mmol BR trial compared with the 6-mmol NIT (p = 0.003) trial as well as compared with PLC (p = 0.010). Plasma nitrite and nitrate concentrations were significantly increased after the ingestion of BR and NIT with the highest concentrations in the 12-mmol trials. Plasma nitrite concentration between NIT and BR did not significantly differ in the 6-mmol (p = 0.27) and in the 12-mmol (p = 0.75) trials. In conclusion, BR might reduce oxygen consumption to a greater extent compared with NIT. PMID:26988767

  1. Knee angle-dependent oxygen consumption during isometric contractions of the knee extensors determined with near-infrared spectroscopy.

    PubMed

    de Ruiter, C J; de Boer, M D; Spanjaard, M; de Haan, A

    2005-08-01

    Fatigue resistance of knee extensor muscles is higher during voluntary isometric contractions at short compared with longer muscle lengths. In the present study we hypothesized that this would be due to lower energy consumption at short muscle lengths. Ten healthy male subjects performed isometric contractions with the knee extensor muscles at a 30, 60, and 90 degrees knee angle (full extension = 0 degrees ). At each angle, muscle oxygen consumption (m.VO2) of the rectus femoris, vastus lateralis, and vastus medialis muscle was obtained with near-infrared spectroscopy. m.VO2 was measured during maximal isometric contractions and during contractions at 10, 30, and 50% of maximal torque capacity. During all contractions, blood flow to the muscle was occluded with a pressure cuff (450 mmHg). m.VO2 significantly (P < 0.05) increased with torque and at all torque levels, and for each of the three muscles. m.VO2 was significantly lower at 30 degrees compared with 60 degrees and 90 degrees and m.VO2 was similar (P > 0.05) at 60 degrees and 90 degrees . Across all torque levels, average (+/- SD) m.VO2 at the 30 degrees angle for vastus medialis, rectus femoris, and vastus lateralis, respectively, was 70.0 +/- 10.4, 72.2 +/- 12.7, and 75.9 +/- 8.0% of the average m.VO2 obtained for each torque at 60 and 90 degrees . In conclusion, oxygen consumption of the knee extensors was significantly lower during isometric contractions at the 30 degrees than at the 60 degrees and 90 degrees knee angle, which probably contributes to the previously reported longer duration of sustained isometric contractions at relatively short muscle lengths.

  2. Sensitivity of hypoxia predictions for the northern Gulf of Mexico to sediment oxygen consumption and model nesting

    NASA Astrophysics Data System (ADS)

    Fennel, Katja; Hu, Jiatang; Laurent, Arnaud; Marta-Almeida, Martinho; Hetland, Robert

    2013-02-01

    Every summer, a large area (15,000 km2 on average) over the Texas-Louisiana shelf in the northern Gulf of Mexico turns hypoxic due to decay of organic matter that is primarily derived from nutrient inputs from the Mississippi/Atchafalaya River System. Interannual variability in the size of the hypoxic zone is large. The 2008 Action Plan put forth by the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force, an alliance of multiple state and federal agencies and tribes, calls for a reduction of the size of the hypoxic zone through nutrient management in the watershed. Comprehensive models help build mechanistic understanding of the processes underlying hypoxia formation and variability and are thus indispensable tools for devising efficient nutrient reduction strategies and for building reasonable expectations as to what responses can be expected for a given nutrient reduction. Here we present such a model, evaluate its hypoxia simulations against monitoring observations, and assess the sensitivity of the hypoxia simulations to model resolution, variations in sediment oxygen consumption, and choice of physical horizontal boundary conditions. We find that hypoxia simulations on the shelf are very sensitive to the parameterization of sediment oxygen consumption, a result of the fact that hypoxic conditions are restricted to a relatively thin layer above the bottom over most of the shelf. We show that the strength of vertical stratification is an important predictor of dissolved oxygen concentration in bottom waters and that modification of physical horizontal boundary conditions can have a large effect on hypoxia simulations because it can affect stratification strength.

  3. Ratings of Perceived Exertion, Heart Rate, and Power Output in Predicting Maximal Oxygen Uptake During Submaximal Cycle Ergometry.

    ERIC Educational Resources Information Center

    Wilmore, Jack H.; And Others

    1986-01-01

    Sixty-two subjects completed a four-stage submaximal cycle ergometer test to determine if estimates of maximal oxygen uptake could be improved by using ratings of perceived exertion singly or in combination with easily obtainable physiological measures. These procedures could be used to estimate the aerobic power of patients and athletes. (MT)

  4. Assessment of mercury toxicity by the changes in oxygen consumption and ion levels in the freshwater snail, Pila globosa, and the mussel, Lamellidens marginalis

    SciTech Connect

    Sivaramakrishna, B.; Radhakrishnaiah, K.; Suresh, A. )

    1991-06-01

    There are many studies on mercury toxicity in freshwater fishes but very few on freshwater molluscs (Wright 1978) though they serve as bio-indicators of metal pollution. A few reports on marine gastropods and bivalves indicated the importance of these animals in metal toxicity studies. Hence, in the present study, the level of tolerance of the freshwater gastropod Pila globosa and of a freshwater bivalve Lamellidens marginalis mercury at lethal and sublethal levels was determined and compared with the rate of whole animal oxygen consumption and the level of sodium, potassium and calcium ions in the hepatopancreas and the foot of these animals. As the period of exposure is one of the important factors in toxicity studies, the level of tolerance was determined at 120 hours of exposure and the other parameters were analyzed at 1, 3 and 5 days in lethal and at 1, 7 and 15 days in sublethal concentrations.

  5. Effects of maternal ingestion of aroclor 1254 (PCB) on the development pattern of oxygen consumption and body temperature in neonatal rats

    SciTech Connect

    Seo, B.W.; Meserve, L.A.

    1995-07-01

    Polychlorinated biphenyl (PCB) is an environmental pollutant that has been implicated in depression of reproductive success in Great Lakes gulls, production of congenital deformities in humans, and increased incidence of carcinogenesis in laboratory mice. PCB has also been shown to be a thyrotoxin in both adult and developing animals. Most recently, the hypothyroid effects of PCB exposure have been reported to elicit effects similar to those of hypothyroidism caused by other methods. This study was done to determine the effects of PCB ingestion in pregnant and lactating rats on the development of thermoregulation in neonatal animals. Body temperature and rate of oxygen consumption was evaluated in rat puts on days 4 through 14 after birth. Because the major thermomregulatory hormones are thyroid hormones, thyroid hormone status and thyroid weights were evaluated at the end of the study on postnatal day 15. 19 refs., 2 figs., 1 tab.

  6. Novel Wireless Sensor System for Monitoring Oxygen, Temperature and Respiration Rate of Horticultural Crops Post Harvest

    PubMed Central

    Løkke, Mette Marie; Seefeldt, Helene Fast; Edwards, Gareth; Green, Ole

    2011-01-01

    In order to design optimal packages, it is of pivotal importance to determine the rate at which harvested fresh fruits and vegetables consume oxygen. The respiration rate of oxygen (RRO2) is determined by measuring the consumed oxygen per hour per kg plant material, and the rate is highly influenced by temperature and gas composition. Traditionally, RRO2 has been determined at discrete time intervals. In this study, wireless sensor networks (WSNs) were used to determine RRO2 continuously in plant material (fresh cut broccoli florets) at 5 °C, 10 °C and 20 °C and at modified gas compositions (decreasing oxygen and increasing carbon dioxide levels). Furthermore, the WSN enabled concomitant determination of oxygen and temperature in the very close vicinity of the plant material. This information proved a very close relationship between changes in temperature and respiration rate. The applied WSNs were unable to determine oxygen levels lower than 5% and carbon dioxide was not determined. Despite these drawbacks in relation to respiration analysis, the WSNs offer a new possibility to do continuous measurement of RRO2 in post harvest research, thereby investigating the close relation between temperature and RRO2. The conclusions are that WSNs have the potential to be used as a monitor of RRO2 of plant material after harvest, during storage and packaging, thereby leading to optimized consumer products. PMID:22164085

  7. Improving the Accuracy of Predicting Maximal Oxygen Consumption (VO2pk)

    NASA Technical Reports Server (NTRS)

    Downs, Meghan E.; Lee, Stuart M. C.; Ploutz-Snyder, Lori; Feiveson, Alan

    2016-01-01

    Maximal oxygen (VO2pk) is the maximum amount of oxygen that the body can use during intense exercise and is used for benchmarking endurance exercise capacity. The most accurate method to determineVO2pk requires continuous measurements of ventilation and gas exchange during an exercise test to maximal effort, which necessitates expensive equipment, a trained staff, and time to set-up the equipment. For astronauts, accurate VO2pk measures are important to assess mission critical task performance capabilities and to prescribe exercise intensities to optimize performance. Currently, astronauts perform submaximal exercise tests during flight to predict VO2pk; however, while submaximal VO2pk prediction equations provide reliable estimates of mean VO2pk for populations, they can be unacceptably inaccurate for a given individual. The error in current predictions and logistical limitations of measuring VO2pk, particularly during spaceflight, highlights the need for improved estimation methods.

  8. Improving the Accuracy of Predicting Maximal Oxygen Consumption (VO2peak)

    NASA Technical Reports Server (NTRS)

    Downs, Meghan E.; Lee, Stuart M. C.; Ploutz-Snyder, Lori; Feiveson, Alan

    2016-01-01

    Maximal oxygen (VO2pk) is the maximum amount of oxygen that the body can use during intense exercise and is used for benchmarking endurance exercise capacity. The most accurate method to determineVO2pk requires continuous measurements of ventilation and gas exchange during an exercise test to maximal effort, which necessitates expensive equipment, a trained staff, and time to set-up the equipment. For astronauts, accurate VO2pk measures are important to assess mission critical task performance capabilities and to prescribe exercise intensities to optimize performance. Currently, astronauts perform submaximal exercise tests during flight to predict VO2pk; however, while submaximal VO2pk prediction equations provide reliable estimates of mean VO2pk for populations, they can be unacceptably inaccurate for a given individual. The error in current predictions and logistical limitations of measuring VO2pk, particularly during spaceflight, highlights the need for improved estimation methods.

  9. Total, chemical, and biological oxygen consumption of the sediments in the Ziya River watershed, China.

    PubMed

    Rong, Nan; Shan, Baoqing

    2016-07-01

    Sediment oxygen demand (SOD) is a critical dissolved oxygen (DO) sink in many rivers. Understanding the relative contributions of the biological and chemical components of SOD would improve our knowledge of the potential environmental harm SOD could cause and allow appropriate management systems to be developed. A various inhibitors addition technique was conducted to measure the total, chemical, and biological SOD of sediment samples from 13 sites in the Ziya River watershed, a severely polluted and anoxic river system in the north of China. The results showed that the major component of SOD was chemical SOD due to iron predominate. The ferrous SOD accounted for 21.6-78.9 % of the total SOD and 33.26-96.79 % of the chemical SOD. Biological SOD represented 41.13 % of the overall SOD averagely. Sulfide SOD accounted for 1.78-45.71 % of the total SOD and it was the secondary predominate of the chemical SOD. Manganous SOD accounted for 1.2-16.6 % of the total SOD and it was insignificant at many sites. Only four kinds of benthos were collected in the Ziya River watershed, resulting from the low DO concentration in the sediment surface due to SOD. This study would be helpful for understanding and preventing the potential sediment oxygen depletion during river restoration. PMID:27026547

  10. Total, chemical, and biological oxygen consumption of the sediments in the Ziya River watershed, China.

    PubMed

    Rong, Nan; Shan, Baoqing

    2016-07-01

    Sediment oxygen demand (SOD) is a critical dissolved oxygen (DO) sink in many rivers. Understanding the relative contributions of the biological and chemical components of SOD would improve our knowledge of the potential environmental harm SOD could cause and allow appropriate management systems to be developed. A various inhibitors addition technique was conducted to measure the total, chemical, and biological SOD of sediment samples from 13 sites in the Ziya River watershed, a severely polluted and anoxic river system in the north of China. The results showed that the major component of SOD was chemical SOD due to iron predominate. The ferrous SOD accounted for 21.6-78.9 % of the total SOD and 33.26-96.79 % of the chemical SOD. Biological SOD represented 41.13 % of the overall SOD averagely. Sulfide SOD accounted for 1.78-45.71 % of the total SOD and it was the secondary predominate of the chemical SOD. Manganous SOD accounted for 1.2-16.6 % of the total SOD and it was insignificant at many sites. Only four kinds of benthos were collected in the Ziya River watershed, resulting from the low DO concentration in the sediment surface due to SOD. This study would be helpful for understanding and preventing the potential sediment oxygen depletion during river restoration.

  11. Temperature-dependent reaction-rate expression for oxygen recombination at Shuttle entry conditions

    NASA Technical Reports Server (NTRS)

    Zoby, E. V.; Simmonds, A. L.; Gupta, R. N.

    1984-01-01

    A temperature-dependent oxygen surface reaction-rate coefficient has been determined from experimental STS-2 heating and wall temperature data at altitudes of 77.91 km, 74.98 km, and 71.29 km. The coefficient is presented in an Arrhenius form and is shown to be less temperature dependent than previous results. Finite-rate viscous-shock-layer heating rates based on this present expression have been compared with predicted heating rates using the previous rate coefficients and with experimental heating data obtained over an extensive range of STS-2 and STS-3 entry conditions. A substantial improvement is obtained in comparison of experimental data and predicted heating rates using the present oxygen reaction-rate expression.

  12. Restoration of Normal Cerebral Oxygen Consumption with Rapamycin Treatment in a Rat Model of Autism-Tuberous Sclerosis.

    PubMed

    Chi, Oak Z; Wu, Chang-Chih; Liu, Xia; Rah, Kang H; Jacinto, Estela; Weiss, Harvey R

    2015-09-01

    Tuberous sclerosis (TSC) is associated with autism spectrum disorders and has been linked to metabolic dysfunction and unrestrained signaling of the mammalian target of rapamycin (mTOR). Inhibition of mTOR by rapamycin can mitigate some of the phenotypic abnormalities associated with TSC and autism, but whether this is due to the mTOR-related function in energy metabolism remains to be elucidated. In young Eker rats, an animal model of TSC and autism, which harbors a germ line heterozygous Tsc2 mutation, we previously reported that cerebral oxygen consumption was pronouncedly elevated. Young (4 weeks) male control Long-Evans and Eker rats were divided into control and rapamycin-treated (20 mg/kg once daily for 2 days) animals. Cerebral regional blood flow ((14)C-iodoantipyrine) and O2 consumption (cryomicrospectrophotometry) were determined in isoflurane-anesthetized rats. We found significantly increased basal O2 consumption in the cortex (8.7 ± 1.5 ml O2/min/100 g Eker vs. 2.7 ± 0.2 control), hippocampus, pons and cerebellum. Regional cerebral blood flow and cerebral O2 extractions were also elevated in all brain regions. Rapamycin had no significant effect on O2 consumption in any brain region of the control rats, but significantly reduced consumption in the cortex (4.1 ± 0.3) and all other examined regions of the Eker rats. Phosphorylation of mTOR and S6K1 was similar in the two groups and equally reduced by rapamycin. Thus, a rapamycin-sensitive, mTOR-dependent but S6K1-independent, signal led to enhanced oxidative metabolism in the Eker brain. We found decreased Akt phosphorylation in Eker but not Long-Evans rat brains, suggesting that this may be related to the increased cerebral O2 consumption in the Eker rat. Our findings suggest that rapamycin targeting of Akt to restore normal cerebral metabolism could have therapeutic potential in tuberous sclerosis and autism.

  13. Resting oxygen consumption varies among lactate dehydrogenase genotypes in the sow bug, Porcellio scaber

    PubMed Central

    Mitton, J. B.; Carter, P. A.; DiGiacomo, A.

    1997-01-01

    Laboratory studies of respiration in the sow bug, Porcellio scaber, reveal that respiration rates are related to genetic variation at the lactate dehydrogenase (Ldh) locus. In population samples taken from Burlington, North Carolina and Pacific Grove, California, respiration rates differed among Ldh genotypes, but not among genotypes at the other enzyme polymorphisms. In both population samples, the respiration rate of the common Ldh homozygote exceeded the respiration rate of the heterozygote by more than 50 per cent. The differences in respiration rates are consistent with previously reported viability differentials at the Ldh polymorphism.

  14. Relationship between work rate and oxygen uptake in mitochondrial myopathy during ramp-incremental exercise.

    PubMed

    Gimenes, A C; Neder, J A; Dal Corso, S; Nogueira, C R; Nápolis, L; Mello, M T; Bulle, A S; Nery, L E

    2011-04-01

    We determined the response characteristics and functional correlates of the dynamic relationship between the rate (Δ) of oxygen consumption (VO(2)) and the applied power output (work rate = WR) during ramp-incremental exercise in patients with mitochondrial myopathy (MM). Fourteen patients (7 males, age 35.4 ± 10.8 years) with biopsy-proven MM and 10 sedentary controls (6 males, age 29.0 ± 7.8 years) took a ramp-incremental cycle ergometer test for the determination of the VO(2) on-exercise mean response time (MRT) and the gas exchange threshold (GET). The ΔVO(2)/ΔWR slope was calculated up to GET (S(1)), above GET (S(2)) and over the entire linear portion of the response (S(T)). Knee muscle endurance was measured by isokinetic dynamometry. As expected, peak VO(2) and muscle performance were lower in patients than controls (P < 0.05). Patients had significantly lower ΔVO(2)/ΔWR than controls, especially the S(2) component (6.8 ± 1.5 vs 10.3 ± 0.6 mL·min(-1)·W(-1), respectively; P < 0.001). There were significant relationships between ΔVO(2)/ΔWR (S(T)) and muscle endurance, MRT-VO(2), GET and peak VO(2) in MM patients (P < 0.05). In fact, all patients with ΔVO(2)/ΔWR below 8 mL·min(-1)·W(-1) had severely reduced peak VO(2) values (<60% predicted). Moreover, patients with higher cardiopulmonary stresses during exercise (e.g., higher Δ ventilation/carbon dioxide output and Δ heart rate/ΔVO(2)) had lower ΔVO(2)/ΔWR (P < 0.05). In conclusion, a readily available, effort-independent index of aerobic dysfunction during dynamic exercise (ΔVO(2)/ΔWR) is typically reduced in patients with MM, being related to increased functional impairment and higher cardiopulmonary stress.

  15. Cardiac resynchronization therapy and AV optimization increase myocardial oxygen consumption, but increase cardiac function more than proportionally☆

    PubMed Central

    Kyriacou, Andreas; Pabari, Punam A.; Mayet, Jamil; Peters, Nicholas S.; Davies, D. Wyn; Lim, P. Boon; Lefroy, David; Hughes, Alun D.; Kanagaratnam, Prapa; Francis, Darrel P.; I.Whinnett, Zachary

    2014-01-01

    Background The mechanoenergetic effects of atrioventricular delay optimization during biventricular pacing (“cardiac resynchronization therapy”, CRT) are unknown. Methods Eleven patients with heart failure and left bundle branch block (LBBB) underwent invasive measurements of left ventricular (LV) developed pressure, aortic flow velocity-time-integral (VTI) and myocardial oxygen consumption (MVO2) at 4 pacing states: biventricular pacing (with VV 0 ms) at AVD 40 ms (AV-40), AVD 120 ms (AV-120, a common nominal AV delay), at their pre-identified individualised haemodynamic optimum (AV-Opt); and intrinsic conduction (LBBB). Results AV-120, relative to LBBB, increased LV developed pressure by a mean of 11(SEM 2)%, p = 0.001, and aortic VTI by 11(SEM 3)%, p = 0.002, but also increased MVO2 by 11(SEM 5)%, p = 0.04. AV-Opt further increased LV developed pressure by a mean of 2(SEM 1)%, p = 0.035 and aortic VTI by 4(SEM 1)%, p = 0.017. MVO2 trended further up by 7(SEM 5)%, p = 0.22. Mechanoenergetics at AV-40 were no different from LBBB. The 4 states lay on a straight line for Δexternal work (ΔLV developed pressure × Δaortic VTI) against ΔMVO2, with slope 1.80, significantly > 1 (p = 0.02). Conclusions Biventricular pacing and atrioventricular delay optimization increased external cardiac work done but also myocardial oxygen consumption. Nevertheless, the increase in cardiac work was ~ 80% greater than the increase in oxygen consumption, signifying an improvement in cardiac mechanoenergetics. Finally, the incremental effect of optimization on external work was approximately one-third beyond that of nominal AV pacing, along the same favourable efficiency trajectory, suggesting that AV delay dominates the biventricular pacing effect — which may therefore not be mainly “resynchronization”. PMID:24332598

  16. Acute larvicidal activity against mosquitoes and oxygen consumption inhibitory activity of dihydroguaiaretic acid derivatives.

    PubMed

    Nishiwaki, Hisashi; Tabara, Yoshimi; Kishida, Taro; Nishi, Kosuke; Shuto, Yoshihiro; Sugahara, Takuya; Yamauchi, Satoshi

    2015-03-11

    (-)-Dihydroguaiaretic acid (DGA) and its derivatives having 3-hydroxyphenyl (3-OH-DGA) and variously substituted phenyl groups instead of 3-hydroxy-4-methoxyphenyl groups were synthesized to measure their larvicidal activity against the mosquito Culex pipiens Linnaeus, 1758 (Diptera: Culicidae). Compared with DGA and 3-OH-DGA (LC50 (M), 3.52 × 10(-5) and 4.57 × 10(-5), respectively), (8R,8'R)-lignan-3-ol (3) and its 3-Me (10), 2-OH (12), 3-OH (13), and 2-OMe (15) derivatives showed low potency (ca. 6-8 × 10(-5) M). The 4-Me derivative (11) showed the lowest potency (12.1 × 10(-5) M), and the 2-F derivative (4) showed the highest (2.01 × 10(-5) M). All of the synthesized compounds induced an acute toxic symptom against mosquito larvae, with potency varying with the type and position of the substituents. The 4-F derivative (6), which killed larvae almost completely within 45 min, suppressed the O2 consumption of the mitochondrial fraction, demonstrating that this compound inhibited mitochondrial O2 consumption contributing to a respiratory inhibitory activity.

  17. Impact of extreme oxygen consumption by pollutants on macroinvertebrate assemblages in plain rivers of the Ziya River Basin, north China.

    PubMed

    Ding, Yuekui; Rong, Nan; Shan, Baoqing

    2016-07-01

    The aim of the study was to estimate the impact of oxygen depletion on macroinvertebrate community structure in benthic space. Macroinvertebrate assemblages and potential of dissolved oxygen (DO) consumption were investigated simultaneously in the plain rivers of the Ziya River Basin. The degree of DO depletion was represented by sediment oxygen demand (SOD) and DO, chemical oxygen demand (CODCr), and ammonia nitrogen (NH4 (+)-N) in the overlying water. The results showed an all-around hypoxia environment formed, and the values of DO, SOD, CODCr, and NH4 (+)-N were separately 0.11-4.03 mg L(-1), 0.41-2.60 g m(-2) day(-1), 27.50-410.00 mg L(-1), and 1.79-101.41 mg L(-1). There was an abnormal macroinvertebrate assemblage, and only 3 classes, Insecta, Gastropoda, and Oligochaeta, were found, which included 9 orders, 30 families, and 54 genera. The biodiversity was at a low level, and Shannon-Wiener index was 0.00-1.72. SOD, and NH4 (+)-N had major impact on the macroinvertebrate community, and the former had negative effect on most taxa, for instance, Nais, Branchiura, Paraleptophlebia, etc., which were sensitive or had a moderate-high tolerance to pollution. NH4 (+)-N had both positive and negative impacts on benthic animals, for instance, Dicrotendipes, Gomphus, Cricotopus, etc., for the former, and Procladius, Limnodrilus, Hippeutis, etc., for the latter. They all had a moderate-high tolerance to pollution. It is significant to improve DO condition and macroinvertebrate diversity in river harnessing and management.

  18. Oxygen Consumption and Usage During Physical Exercise: The Balance Between Oxidative Stress and ROS-Dependent Adaptive Signaling

    PubMed Central

    Zhao, Zhongfu; Koltai, Erika; Ohno, Hideki; Atalay, Mustafa

    2013-01-01

    Abstract The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1α activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and protein–protein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROS-mediated activation of hypoxia-inducible factor 1α. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling. Antioxid. Redox Signal. 18, 1208–1246. PMID:22978553

  19. Impact of extreme oxygen consumption by pollutants on macroinvertebrate assemblages in plain rivers of the Ziya River Basin, north China.

    PubMed

    Ding, Yuekui; Rong, Nan; Shan, Baoqing

    2016-07-01

    The aim of the study was to estimate the impact of oxygen depletion on macroinvertebrate community structure in benthic space. Macroinvertebrate assemblages and potential of dissolved oxygen (DO) consumption were investigated simultaneously in the plain rivers of the Ziya River Basin. The degree of DO depletion was represented by sediment oxygen demand (SOD) and DO, chemical oxygen demand (CODCr), and ammonia nitrogen (NH4 (+)-N) in the overlying water. The results showed an all-around hypoxia environment formed, and the values of DO, SOD, CODCr, and NH4 (+)-N were separately 0.11-4.03 mg L(-1), 0.41-2.60 g m(-2) day(-1), 27.50-410.00 mg L(-1), and 1.79-101.41 mg L(-1). There was an abnormal macroinvertebrate assemblage, and only 3 classes, Insecta, Gastropoda, and Oligochaeta, were found, which included 9 orders, 30 families, and 54 genera. The biodiversity was at a low level, and Shannon-Wiener index was 0.00-1.72. SOD, and NH4 (+)-N had major impact on the macroinvertebrate community, and the former had negative effect on most taxa, for instance, Nais, Branchiura, Paraleptophlebia, etc., which were sensitive or had a moderate-high tolerance to pollution. NH4 (+)-N had both positive and negative impacts on benthic animals, for instance, Dicrotendipes, Gomphus, Cricotopus, etc., for the former, and Procladius, Limnodrilus, Hippeutis, etc., for the latter. They all had a moderate-high tolerance to pollution. It is significant to improve DO condition and macroinvertebrate diversity in river harnessing and management. PMID:27048327

  20. The effects of hypothermia on myocardial oxygen consumption and transmural coronary blood flow in the potassium-arrested heart.

    PubMed Central

    Chitwood, W R; Sink, J D; Hill, R C; Wechsler, A S; Sabiston, D C

    1979-01-01

    Hypothermia remains the primary adjunct employed to lower cellular metabolism during various cardiac procedures. In these experiments, left ventricular myocardial oxygen consumption (MVO2) and transmural blood flow (TBF) were measured during cardiopulmonary bypass with the range of temperatures used clinically. Determinations were made in empty beating normothermic hearts and after potassium cardioplegia at 37, 32, 28, 22, 18, and 15 degrees (K+ = 15--37 meq/L: Hct 25 volumes %). Oxygen content of the total coronary sinus collection was compared with a large volume arterial sample using a Lex-O2-Con-TL analyzer (vs Van Slyke, R = 0.98). Transmural blood flow was measured at each temperature using microspheres (8 microns), and perfusion was maintained at 80 mmHg. Asystole (37 degrees) alone decreased MVO2 from 5.18 +/- 0.55 to 1.85 +/- 0.20 ml O2/min/100 g of left ventricle or approximately 65% (p less than 0.001). With progressive cooling to 15 degrees an additional 82% decrement in oxygen uptake occurred during asystole (p less than 0.001). During asystole at 37 degrees the decrease in MVO2 was reflected mainly by a large decrement (p less than 0.01) in TBF (1.27 +/- 0.19 to 0.74 +/- 0.17 ml/min/g of mean left ventricular flow). However, with cooling below 32 degrees, the arteriovenous oxygen difference narrowed progressively (p less than 0.001) while TBF paradoxically returned to control levels. Endocardial/epicardial flow ratios were not altered by cooling. These data not only confirm earlier reports describing a sequential drop in MVO2 with incremental myocardial cooling, but also establish MVO2 levels for perfused hearts arrested by potassium at lower temperatures (18--15 degrees). Moreover, as transmural blood flow becomes independent of metabolic necessity during hypothermia, coronary autoregulation appears to be impaired, possibly affecting detrimental tissue over perfusion. PMID:464672

  1. Effect of Oxygen-Supply Rates on Growth of Escherichia coli

    PubMed Central

    McDaniel, L. E.; Bailey, E. G.; Zimmerli, A.

    1965-01-01

    The effect of oxygen-supply rates on bacterial growth was studied in commercially available unbaffled and baffled flasks with the use of Escherichia coli in a synthetic medium as a test system. The amount of growth obtained depended on the oxygen-supply rate. Based on oxygen-absorption rates (OAR) measured by the rate of sulfite oxidation, equal OAR values in different types of flasks did not give equal amounts of growth. However, growth was essentially equal at the equal sulfite-oxidation rates when these were determined in the presence of killed whole cultures. Specific growth rates were reduced only at oxygen-supply rates much lower than those at which the total amount of growth was reduced. For the physical set-up used in this work and with the biological system employed, Bellco 598 flasks and flasks fitted with Biotech stainless-steel baffles gave satisfactory results at workable broth volumes; unbaffled and Bellco 600 flasks did not. PMID:14264837

  2. Functional linkage between N acquisition strategies and aeration capacities of hydrophytes for efficient oxygen consumption in roots.

    PubMed

    Nakamura, Motoka; Nakamura, Takatoshi; Tsuchiya, Takayoshi; Noguchi, Ko

    2013-02-01

    We evaluated the specific strategies of hydrophytes for root O(2) consumption in relation to N acquisition and investigated whether the strategies varied depending on the aeration capacity. Aeration capacity of roots is an important factor for determining hypoxia tolerance in plants. However, some hydrophytes possessing quite different aeration capacities often co-occur in wetlands, suggesting that root O(2) consumption also strongly affects hypoxia tolerance. We cultivated Phragmites australis with high aeration capacity and Zizania latifolia with low aeration capacity in hypoxic conditions with NH(4)(+) or NO(3)(-) treatment and compared the growth, N uptake, N assimilation and root respiration between the two species. In Z. latifolia grown with NH(4)(+) treatment, high N uptake activity and restrained root growth led to sufficient N acquisition and decrease in whole-root respiration rate. These characteristics consequently compensated for the low aeration capacity. In contrast, in P. australis, low N uptake activity was compensated by active root growth, but the whole-root respiration rate was high. This high root respiration rate was allowed by the high aeration capacity. The O(2) consumption-related traits of hydrophyte roots were closely correlated with N acquisition strategies, which consequently led to a compensational relationship with the root aeration capacity. It is likely that this functional linkage plays an important role as a core mechanism in the adaptation of plants to hypoxic soils.

  3. Functional linkage between N acquisition strategies and aeration capacities of hydrophytes for efficient oxygen consumption in roots.

    PubMed

    Nakamura, Motoka; Nakamura, Takatoshi; Tsuchiya, Takayoshi; Noguchi, Ko

    2013-02-01

    We evaluated the specific strategies of hydrophytes for root O(2) consumption in relation to N acquisition and investigated whether the strategies varied depending on the aeration capacity. Aeration capacity of roots is an important factor for determining hypoxia tolerance in plants. However, some hydrophytes possessing quite different aeration capacities often co-occur in wetlands, suggesting that root O(2) consumption also strongly affects hypoxia tolerance. We cultivated Phragmites australis with high aeration capacity and Zizania latifolia with low aeration capacity in hypoxic conditions with NH(4)(+) or NO(3)(-) treatment and compared the growth, N uptake, N assimilation and root respiration between the two species. In Z. latifolia grown with NH(4)(+) treatment, high N uptake activity and restrained root growth led to sufficient N acquisition and decrease in whole-root respiration rate. These characteristics consequently compensated for the low aeration capacity. In contrast, in P. australis, low N uptake activity was compensated by active root growth, but the whole-root respiration rate was high. This high root respiration rate was allowed by the high aeration capacity. The O(2) consumption-related traits of hydrophyte roots were closely correlated with N acquisition strategies, which consequently led to a compensational relationship with the root aeration capacity. It is likely that this functional linkage plays an important role as a core mechanism in the adaptation of plants to hypoxic soils. PMID:22575011

  4. Health Care Consumption among Elderly Patients in California: A Comprehensive 10-Year Evaluation of Trends in Hospitalization Rates and Charges

    ERIC Educational Resources Information Center

    Koziol, James A.; Zuraw, Bruce L.; Christiansen, Sandra C.

    2002-01-01

    Purpose: This report examines health care rates, charges, and patterns of consumption from a comprehensive California hospitalization data set covering 1986-1995. An improved understanding of current trends in health care consumption would facilitate the development of future resource allocation models. Design and Methods: We obtained discharge…

  5. Relationships between butterflyfish (Chaetodontidae) feeding rates and coral consumption on the Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Gregson, M. A.; Pratchett, M. S.; Berumen, M. L.; Goodman, B. A.

    2008-09-01

    This study explored differences in the feeding rate among 20 species of coral reef butterflyfishes (Chaetodontidae) from Lizard Island, Great Barrier Reef. Feeding rate, measured as bites per minute (b.p.m.), varied between 2.98 ± 0.65 and 12.29 ± 0.27 (mean ± SE) according to species and was positively related to the proportional consumption of coral ( r 2 = 0.40, n = 20, P < 0.01), independent of phylogeny (standardised independent contrasts r 2 = 0.29, n = 19, P < 0.05). All species fed actively throughout the day, with obligate corallivores having a higher feeding rate at all times than either facultative corallivores or non-corallivores. The feeding rate of the obligate corallivores was also highest during the middle of the day. For eight of the species for which data was available, there was a positive correlation between bite rate and competitive dominance ( r = 0.71, P < 0.05). Chaetodon ephippium was the only species for which the feeding rate of pairs was higher than for solitary individuals.

  6. On the Mechanism by Which Vascular Endothelial Cells Regulate Their Oxygen Consumption

    NASA Astrophysics Data System (ADS)

    Clementi, Emilio; Brown, Guy Charles; Foxwell, Neale; Moncada, Salvador

    1999-02-01

    Two enzymes, soluble guanylyl cyclase and cytochrome c oxidase, have been shown to be exquisitely sensitive to nitric oxide (NO) at low physiological concentrations. Activation of the soluble guanylyl cyclase by endogenous NO and the consequent increase in the second messenger cyclic GMP are now known to control a variety of biological functions. Cytochrome c oxidase, the terminal enzyme of the mitochondrial respiratory chain, is inhibited by NO. However, it is not clear whether NO produced by the constitutive NO synthase interacts with cytochrome c oxidase, nor is it known what the biological consequences of such an interaction might be. We now show that NO generated by vascular endothelial cells under basal and stimulated conditions modulates the respiration of these cells in response to acute changes in oxygen concentration. This action occurs at the cytochrome c oxidase and depends on influx of calcium. Thus, NO plays a physiological role in adjusting the capacity of this enzyme to use oxygen, allowing endothelial cells to adapt to acute changes in their environment.

  7. Hyporheic exchange and oxygen consumption under losing and gaining flow conditions

    NASA Astrophysics Data System (ADS)

    Arnon, S.; Fox, A.; De Falco, N.; Boano, F.

    2013-12-01

    The exchange of water between the surface and subsurface environments plays a crucial role in hydrological, biogeochemical, and ecological processes. The exchange of water is driven by the local morphology of the streambed (hyporheic exchange) and regional forcing of the hydraulic gradient, which results in losing or gaining flow conditions. We measured the effects of losing and gaining flow conditions on hyporheic exchange fluxes by conducting tracer experiments using a novel laboratory flume system (640 cm long and 30 cm wide) under various combinations of overlying velocities and losing/gaining fluxes. Tracer experiments for measuring hyporheic exchange were done using NaCl as conservative tracer, and dye tracer to visualize the active region where water exchange processes occur. Hyporheic exchange fluxes were analyzed based on a new conceptual framework, which relies on a solute mass balance with sink/source terms due to losing/gaining fluxes to evaluate water exchange between surface flow and streambed sediments. This combination of experimental observations and modeling revealed that hyporheic exchange fluxes under losing and gaining flow conditions was similar. Interfacial transport increases proportional to the square of the overlying velocity, and linearly with increasing fluxes of losing and gaining conditions in the sand bed. When the regional hydraulic forcing becomes larger, the hyporheic exchange becomes smaller. Thus, losing and gaining flow conditions becomes the dominant mechanism of water exchange at a certain flux, which depends on the competitive interaction between the overlying velocity in the stream and the losing/gaining fluxes. This type of coupling is expected to regulate nutrient and contaminant transport and microbial activity in streams and rivers. Indeed, we demonstrated using oxygen distribution along the bedform, which was measured using microelectrodes, that the local hydraulic conditions have a strong influent on microbial activity

  8. Polymer etching in the oxygen afterglow - Increased etch rates with increased reactor loading

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Wydeven, T.

    1989-01-01

    Reactor loading has an effect on the etch rate (rate of decrease of film thickness) of films of polyvinylfluoride (Tedlar) and polyethylene exposed in the afterglow of an RF discharge in oxygen. The etch rate is found to increase with the total surface area of the polymer exposed in the reactor. The etch rates of polypyromellitimide (Kapton H) and polystyrene under these conditions are very low. However, the etch rate of these polymers is greatly enhanced by adding either Tedlar or polyethylene to the reactor. A kinetic model is proposed based on the premise that the oxygen atoms produced by the RF discharge react with Tedlar or polyethylene to produce a much more reactive species, which dominates the etching of the polymers studied.

  9. Validation of measurement protocols to assess oxygen consumption and blood flow in the human forearm by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    van Beekvelt, Mireille C.; Colier, Willy N.; van Engelen, Baziel G.; Hopman, Maria T.; Wevers, Ron A.; Oeseburg, Berend

    1997-12-01

    Near infrared spectroscopy (NIRS) has been used to monitor oxygenation changes in muscle. Quantitative values for O2 consumption, blood flow and venous saturation have been reported by several investigators. The amount of these measurements is, however, still limited and complete validation has not yet been established. The aim of this study was to investigate the different NIRS methods to calculate O2 consumption (VO2) and forearm blood flow (FBF) and to validate the data with the accepted method of strain-gauge plethysmography and blood sampling. Thirteen subjects were tested in rest and during static isometric handgrip exercise at 10% MVC. The NIRS optodes were positioned on the flexor region of the arm. A significant correlation was found between plethysmograph data and NIRS [tHb] during venous occlusion in rest (r EQ 0.925 - 0.994, P < 0.05) as well as during exercise (r equals 0.895 - 0.990, P < 0.05). No correlation was found, however, for the calculated FBF and VO2 values between NIRS and the combination of plethysmography and blood sampling. In rest nor during exercise. It seems that although NIRS is a good qualitative monitoring technique, quantification is difficult due to the great variability that is found between the subjects.

  10. Validation of measurement protocols to assess oxygen consumption and blood flow in the human forearm by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Van Beekvelt, Mireille C. P.; Colier, Willy N.; van Engelen, Baziel G. M.; Hopman, Maria T. E.; Wevers, Ron A.; Oeseburg, Berend

    1998-01-01

    Near infrared spectroscopy (NIRS) has been used to monitor oxygenation changes in muscle. Quantitative values for O2 consumption, blood flow and venous saturation have been reported by several investigators. The amount of these measurements is, however, still limited and complete validation has not yet been established. The aim of this study was to investigate the different NIRS methods to calculate O2 consumption (VO2) and forearm blood flow (FBF) and to validate the data with the accepted method of strain-gauge plethysmography and blood sampling. Thirteen subjects were tested in rest and during static isometric handgrip exercise at 10% MVC. The NIRS optodes were positioned on the flexor region of the arm. A significant correlation was found between plethysmograph data and NIRS [tHb] during venous occlusion in rest (r EQ 0.925 - 0.994, P < 0.05) as well as during exercise (r equals 0.895 - 0.990, P < 0.05). No correlation was found, however, for the calculated FBF and VO2 values between NIRS and the combination of plethysmography and blood sampling. In rest nor during exercise. It seems that although NIRS is a good qualitative monitoring technique, quantification is difficult due to the great variability that is found between the subjects.

  11. Contributions to elevated metabolism during recovery: dissecting the excess postexercise oxygen consumption (EPOC) in the desert iguana (Dipsosaurus dorsalis).

    PubMed

    Hancock, Thomas V; Gleeson, Todd T

    2008-01-01

    The excess postexercise oxygen consumption (EPOC), a measure of recovery costs, is known to be large in ectothermic vertebrates such as the desert iguana (Dipsosaurus dorsalis), especially after vigorous activity. To analyze the cause of these large recovery costs in a terrestrial ectotherm, Dipsosaurus were run for 15 s at maximal-intensity (distance 35.0+/-1.9 m; 2.33+/-0.13 m s(-1)) while O(2) uptake was monitored via open-flow respirometry. Muscle metabolites (adenylates, phosphocreatine, and lactate) were measured at rest and after 0, 3, 10, and 60 min of recovery. Cardiac and ventilatory activity during rest and recovery were measured, as were whole-body lactate and blood lactate, which were used to estimate total muscle activity. This vigorous activity was supported primarily by glycolysis (65%) and phosphocreatine hydrolysis (29%), with only a small contribution from aerobic metabolism (2.5%). Aerobic recovery lasted 43.8+/-4.6 min, and EPOC measured 0.166+/-0.025 mL O(2) g(-1). This was a large proportion (98%) of the total suprabasal metabolic cost of the activity to the animal. The various contributions to EPOC after this short but vigorous activity were quantified, and a majority of EPOC was accounted for. The two primary causes of EPOC were phosphocreatine repletion (32%-50%) and lactate glycogenesis (30%-47%). Four other components played smaller roles: ATP repletion (8%-13%), elevated ventilatory activity (2%), elevated cardiac activity (2%), and oxygen store resaturation (1%).

  12. Zinc-induced structural effects enhance oxygen consumption and superoxide generation in synthetic pheomelanins on UVA/visible light irradiation.

    PubMed

    Panzella, Lucia; Szewczyk, Grzegorz; d'Ischia, Marco; Napolitano, Alessandra; Sarna, Tadeusz

    2010-01-01

    The abnormal susceptibility of red-haired individuals to UV-induced inflammation and skin cancers is commonly attributed to the marked photoreactivity of pheomelanin pigments, which would be responsible for the sustained generation of reactive oxygen species in the skin following sun exposure. The structural factors determining pheomelanin photolability remain mostly unknown. Here, we describe the effects of zinc ions, typically found at high levels in red hair, in enhancing both oxygen consumption and superoxide production in model pheomelanin pigments following irradiation with UVA and visible light. Electron paramagnetic resonance (EPR) oximetry and EPR-spin trapping experiments with synthetic pheomelanins, prepared by oxidation of dopa and cysteine or isomeric cysteinyldopas under different conditions, indicate a higher photoreactivity of the pigments prepared in the presence of zinc ions compared with those obtained in the absence of the metal. Quantitative analysis of thiazole-containing structural markers of the synthetic pheomelanins provides evidence that the effect of zinc ions is due to modification of the formation pathway and structural features of the pigments. Overall, these results point to a hitherto unrecognized critical role of zinc ions in pheomelanogenesis, which may affect the intrinsic photoreactivity of the pigment.

  13. Consumption rates and prey preference of the invasive gastropod Rapana venosa in the Northern Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Savini, Dario; Occhipinti-Ambrogi, Anna

    2006-05-01

    The alien Asian gastropod Rapana venosa (Valenciennes 1846) was first recorded in 1973 along the Italian coast of the Northern Adriatic Sea. Recently, this predator of bivalves has been spreading all around the world oceans, probably helped by ship traffic and aquaculture trade. A caging experiment in natural environment was performed during the summer of 2002 in Cesenatico (Emilia-Romagna, Italy) in order to estimate consumption rates and prey preference of R. venosa. The prey items chosen were the Mediterranean mussel Mytilus galloprovincialis (Lamarck 1819), the introduced carpet clam Tapes philippinarum (Adams and Reeve 1850), both supporting the local fisheries, and the Indo-Pacific invasive clam Anadara (Scapharca) inaequivalvis (Bruguière 1789). Results showed an average consumption of about 1 bivalve prey per day (or 1.2 g wet weight per day). Predation was species and size selective towards small specimens of A. inaequivalvis; consumption of the two commercial species was lower. These results might reduce the concern about the economical impact on the local bivalve fishery due to the presence of the predatory gastropod. On the other hand, selective predation might probably alter local community structure, influencing competition amongst filter feeder/suspension feeder bivalve species and causing long-term ecological impact. The large availability of food resource and the habitat characteristics of the Emilia-Romagna littoral makes this area an important breeding ground for R. venosa in the Mediterranean Sea, thus worthy of consideration in order to understand the bioinvasion ecology of this species and to control its likely further dispersal.

  14. Where the O2 goes to: preservation of human fetal oxygen delivery and consumption at high altitude

    PubMed Central

    Postigo, Lucrecia; Heredia, Gladys; Illsley, Nicholas P; Torricos, Tatiana; Dolan, Caitlin; Echalar, Lourdes; Tellez, Wilma; Maldonado, Ivan; Brimacombe, Michael; Balanza, Elfride; Vargas, Enrique; Zamudio, Stacy

    2009-01-01

    Fetal growth is decreased at high altitude (> 2700 m). We hypothesized that variation in fetal O2 delivery might account for both the altitude effect and the relative preservation of fetal growth in multigenerational natives to high altitude. Participants were 168 women of European or Andean ancestry living at 3600 m or 400 m. Ancestry was genetically confirmed. Umbilical vein blood flow was measured using ultrasound and Doppler. Cord blood samples permitted calculation of fetal O2 delivery and consumption. Andean fetuses had greater blood flow and oxygen delivery than Europeans and weighed more at birth, regardless of altitude (+208 g, P < 0.0001). Fetal blood flow was decreased at 3600 m (P < 0.0001); the decrement was similar in both ancestry groups. Altitude-associated decrease in birth weight was greater in Europeans (−417 g) than Andeans (−228 g, P < 0.005). Birth weight at 3600 m was > 200 g lower for Europeans at any given level of blood flow or O2 delivery. Fetal haemoglobin concentration was increased, decreased, and the fetal / curve was left-shifted at 3600 m. Fetuses receiving less O2 extracted more (r2= 0.35, P < 0.0001). These adaptations resulted in similar fetal O2 delivery and consumption across all four groups. Increased umbilical venous O2 delivery correlated with increased fetal O2 consumption per kg weight (r2= 0.50, P < 0.0001). Blood flow (r2= 0.16, P < 0.001) and O2 delivery (r2= 0.17, P < 0.001) correlated with birth weight at 3600 m, but not at 400 m (r2= 0.04, and 0.03, respectively). We concluded that the most pronounced difference at high altitude is reduced fetal blood flow, but fetal haematological adaptation and fetal capacity to increase O2 extraction indicates that deficit in fetal oxygen delivery is unlikely to be causally associated with the altitude- and ancestry-related differences in fetal growth. PMID:19074967

  15. A cytochrome C oxidase model catalyzes oxygen to water reduction under rate-limiting electron flux.

    PubMed

    Collman, James P; Devaraj, Neal K; Decréau, Richard A; Yang, Ying; Yan, Yi-Long; Ebina, Wataru; Eberspacher, Todd A; Chidsey, Christopher E D

    2007-03-16

    We studied the selectivity of a functional model of cytochrome c oxidase's active site that mimics the coordination environment and relative locations of Fe(a3), Cu(B), and Tyr(244). To control electron flux, we covalently attached this model and analogs lacking copper and phenol onto self-assembled monolayer-coated gold electrodes. When the electron transfer rate was made rate limiting, both copper and phenol were required to enhance selective reduction of oxygen to water. This finding supports the hypothesis that, during steady-state turnover, the primary role of these redox centers is to rapidly provide all the electrons needed to reduce oxygen by four electrons, thus preventing the release of toxic partially reduced oxygen species. PMID:17363671

  16. Role of self-caught fish in total fish consumption rates for recreational fishermen: Average consumption for some species exceeds allowable intake.

    PubMed

    Burger, Joanna

    2013-01-01

    Studies of fish consumption focus on recreational or subsistence fishing, on awareness and adherence to advisories, consumption patterns, and contaminants in fish. Yet the general public obtains their fish from commercial sources. In this paper I examine fish consumption patterns of recreational fishermen in New Jersey to determine: 1) consumption rates for self-caught fish and for other fish, 2) meals consumed per year, 3) average meal size, and average daily intake of mercury, and 4) variations in these parameters for commonly-consumed fish, and different methods of computing intake. Over 300 people were interviewed at fishing sites and fishing clubs along the New Jersey shore. Consumption patterns of anglers varied by species of fish. From 2 to 90 % of the anglers ate the different fish species, and between 9 and 75 % gave fish away to family or friends. Self-caught fish made up 7 to 92 % of fish diets. On average, self-caught fish were eaten for only 2 to 6 months of the year, whereas other fish (commercial or restaurant) were eaten up to 10 months a year. Anglers consumed from 5 to 36 meals of different fish a year, which resulted in intake of mercury ranging from 0.01 to 0.22 ug/kg/day. Average intake of Mako shark, swordfish, and tuna (sushi, canned tuna, self-caught tuna) exceeded the U.S. Environmental Protection Agency's oral, chronic reference dose for mercury of 0.1 ug/kg/day. However, computing intake using consumption for the highest month results in average mercury intake exceeding the reference dose for striped bass and bluefish as well. These data, and the variability in consumption patterns, have implications for risk assessors, risk managers, and health professionals. PMID:23914136

  17. Role of self-caught fish in total fish consumption rates for recreational fishermen: Average consumption for some species exceeds allowable intake

    PubMed Central

    Burger, Joanna

    2013-01-01

    Studies of fish consumption focus on recreational or subsistence fishing, on awareness and adherence to advisories, consumption patterns, and contaminants in fish. Yet the general public obtains their fish from commercial sources. In this paper I examine fish consumption patterns of recreational fishermen in New Jersey to determine: 1) consumption rates for self-caught fish and for other fish, 2) meals consumed per year, 3) average meal size, and average daily intake of mercury, and 4) variations in these parameters for commonly-consumed fish, and different methods of computing intake. Over 300 people were interviewed at fishing sites and fishing clubs along the New Jersey shore. Consumption patterns of anglers varied by species of fish. From 2 to 90 % of the anglers ate the different fish species, and between 9 and 75 % gave fish away to family or friends. Self-caught fish made up 7 to 92 % of fish diets. On average, self-caught fish were eaten for only 2 to 6 months of the year, whereas other fish (commercial or restaurant) were eaten up to 10 months a year. Anglers consumed from 5 to 36 meals of different fish a year, which resulted in intake of mercury ranging from 0.01 to 0.22 ug/kg/day. Average intake of Mako shark, swordfish, and tuna (sushi, canned tuna, self-caught tuna) exceeded the U.S. Environmental Protection Agency’s oral, chronic reference dose for mercury of 0.1 ug/kg/day. However, computing intake using consumption for the highest month results in average mercury intake exceeding the reference dose for striped bass and bluefish as well. These data, and the variability in consumption patterns, have implications for risk assessors, risk managers, and health professionals. PMID:23914136

  18. Tracking Changes in Maximal Oxygen Consumption with the Heart Rate Index in Female Collegiate Soccer Players

    PubMed Central

    Esco, Michael R.; Snarr, Ronald L.; Flatt, Andrew; Leatherwood, Matthew; Whittaker, Adam

    2014-01-01

    The purpose of this study was to determine if the HRindex Method (VO2max = [6 x HRindex – 5] x 3.5, where HRindex = HRmax/HRrest) was accurate for tracking changes in VO2max following 8-weeks of endurance training among collegiate female soccer players. Predicted VO2max via the HRindex Method and observed VO2max from a maximal exercise test on a treadmill were determined for a group of female soccer athletes (n = 15) before and following an 8-week endurance training protocol. The predicted (pVO2max) and observed (aVO2max) values were compared at baseline and within 1-week post-training. Change values (i.e., the difference between pre to post) for each variable were also determined and compared. There was a significant difference between aVO2max before (43.2 ± 2.8 ml·kg·min−1) and following (46.2 ± 2.1 ml·kg·min−1) the 8-week training program (p < 0.05). However, pVO2max did not significantly change following training (pre = 43.4 ± 4.6 ml·kg·min−1, post = 42.9 ± 4.1 ml·kg·min−1, p = 0.53). Furthermore, the correlation between the change in aVO2max and the change in pVO2max was trivial and non-significant (r = 0.30, p = 0.28). The HRindex Method does not appear to be suitable for predicting changes in VO2max following 8-weeks of endurance training in female collegiate soccer players. PMID:25414744

  19. Extracellular flux analysis to monitor glycolytic rates and mitochondrial oxygen consumption.

    PubMed

    Pelletier, Martin; Billingham, Leah K; Ramaswamy, Madhu; Siegel, Richard M

    2014-01-01

    Evidence accumulating over the past decade has linked alterations in bioenergetic metabolism to the pathogenesis of several diseases, including inflammatory conditions and cancer. However, the mutual relationship between the effector functions and the metabolism of immune cells has begun to emerge only recently. Similar to malignant cells, both innate and adaptive immune cells undergo a metabolic reprogramming that is required for effector functions, de facto underlying the elicitation of a robust immune response. These changes allow immune cells not only to rapidly respond to pathogens or (pre)malignant cells but also to adapt to changing microenvironmental conditions. Targeting the metabolic alterations of malignant cells has been the subject of an intense wave of investigation, resulting in the identification of promising therapeutic strategies. Since the inflammatory milieu and the tumor microenvironment are similar, the metabolism of immune cells and its regulation has recently come under renewed interest as a target for immunotherapy. Here, we describe different tools and techniques to study the bioenergetic metabolism of cultured cells, using immune cells as a model. Our methodological approach relies on an extracellular flux analyzer, an instrument that enables the real-time measurement of the two central pathways used by living cells to generate adenosine triphosphate: glycolysis and oxidative phosphorylation. This instrument and similar technological innovations have transformed the study of cellular metabolism, unveiling its profound impact on various immunologic and oncological disorders.

  20. Moderate dose of watercress and red radish does not reduce oxygen consumption during graded exhaustive exercise

    PubMed Central

    Meamarbashi, Abbas; Alipour, Meysam

    2014-01-01

    Objective: Very recent studies have reported positive effects of dietary nitrate on the oxygen consumption during exercise. This research aimed to study the effect of moderate dose of high-nitrate vegetables, watercress (Nasturtium officinale) and red radish (Raphanus sativus) compared with a control group on the incremental treadmill exercise test following a standard Bruce protocol controlled by computer. Materials and Methods: Group 1 consumed 100 g watercress (n=11, 109.5 mg nitrate/day), and group 2 consumed 100 g red radish (n=11, mg 173.2 mg nitrate/day) for seven days, and control group (n=14) was prohibited from high nitrate intake. Results: During exercise, watercress group showed significant changes in the maximum values of Respiratory Exchange Ratio (RER) (p<0.05), End-Tidal O2 Fraction (FETO2) (p<0.05), and energy consumption from carbohydrate (p<0.01). Red radish group had a significant increase in the VCO2 (p<0.01), RER (p<0.01), VT (p<0.05), VCO2/kg (p<0.05), and energy consumption from carbohydrates (p<0.01). When all groups in the same workload were normalized by the subject’s body mass, watercress had a significant increase in the total expired CO2 (p<0.05), RER (p<0.05), FETO2 (p<0.05), and energy consumption from carbohydrates (p<0.05) compared with the control group. Similar comparison between red radish and control group revealed a significant increase during pre-test in the total CO2 production (p<0.05), VCO2 (p<0.05), RER (p<0.01), VT (p<0.05), and VCO2/kg (p<0.05). Conclusion : Current results indicate higher carbon dioxide production in the experimental groups in the same workload. This might have a negative impact on the exercise performance. Further investigations with controlled exercise program will be necessary. PMID:25068141

  1. An Equation for the Prediction of Oxygen Consumption in a Brazilian Population.

    PubMed

    Almeida, Antonio Eduardo Monteiro de; Stefani, Charles de Moraes; Nascimento, João Agnaldo do; Almeida, Narla Miranda de; Santos, Amilton da Cruz; Ribeiro In Memoriam, Jorge Pinto; Stein, Ricardo

    2014-09-12

    Background: The equations predicting maximal oxygen uptake (VO2max or peak) presently in use in cardiopulmonary exercise testing (CPET) softwares in Brazil have not been adequately validated. These equations are very important for the diagnostic capacity of this method. Objective: Build and validate a Brazilian Equation (BE) for prediction of VO2peak in comparison to the equation cited by Jones (JE) and the Wasserman algorithm (WA). Methods: Treadmill evaluation was performed on 3119 individuals with CPET (breath by breath). The construction group (CG) of the equation consisted of 2495 healthy participants. The other 624 individuals were allocated to the external validation group (EVG). At the BE (derived from a multivariate regression model), age, gender, body mass index (BMI) and physical activity level were considered. The same equation was also tested in the EVG. Dispersion graphs and Bland-Altman analyses were built. Results: In the CG, the mean age was 42.6 years, 51.5% were male, the average BMI was 27.2, and the physical activity distribution level was: 51.3% sedentary, 44.4% active and 4.3% athletes. An optimal correlation between the BE and the CPET measured VO2peak was observed (0.807). On the other hand, difference came up between the average VO2peak expected by the JE and WA and the CPET measured VO2peak, as well as the one gotten from the BE (p = 0.001). Conclusion: BE presents VO2peak values close to those directly measured by CPET, while Jones and Wasserman differ significantly from the real VO2peak. PMID:25229356

  2. An Equation for the Prediction of Oxygen Consumption in a Brazilian Population.

    PubMed

    Almeida, Antonio Eduardo Monteiro de; Stefani, Charles de Moraes; Nascimento, João Agnaldo do; Almeida, Narla Miranda de; Santos, Amilton da Cruz; Ribeiro In Memoriam, Jorge Pinto; Stein, Ricardo

    2014-09-12

    Background: The equations predicting maximal oxygen uptake (VO2max or peak) presently in use in cardiopulmonary exercise testing (CPET) softwares in Brazil have not been adequately validated. These equations are very important for the diagnostic capacity of this method. Objective: Build and validate a Brazilian Equation (BE) for prediction of VO2peak in comparison to the equation cited by Jones (JE) and the Wasserman algorithm (WA). Methods: Treadmill evaluation was performed on 3119 individuals with CPET (breath by breath). The construction group (CG) of the equation consisted of 2495 healthy participants. The other 624 individuals were allocated to the external validation group (EVG). At the BE (derived from a multivariate regression model), age, gender, body mass index (BMI) and physical activity level were considered. The same equation was also tested in the EVG. Dispersion graphs and Bland-Altman analyses were built. Results: In the CG, the mean age was 42.6 years, 51.5% were male, the average BMI was 27.2, and the physical activity distribution level was: 51.3% sedentary, 44.4% active and 4.3% athletes. An optimal correlation between the BE and the CPET measured VO2peak was observed (0.807). On the other hand, difference came up between the average VO2peak expected by the JE and WA and the CPET measured VO2peak, as well as the one gotten from the BE (p = 0.001). Conclusion: BE presents VO2peak values close to those directly measured by CPET, while Jones and Wasserman differ significantly from the real VO2peak.

  3. An Equation for the Prediction of Oxygen Consumption in a Brazilian Population

    PubMed Central

    de Almeida, Antonio Eduardo Monteiro; Stefani, Charles de Moraes; do Nascimento, João Agnaldo; de Almeida, Narla Miranda; Santos, Amilton da Cruz; Stein, Ricardo

    2014-01-01

    Background The equations predicting maximal oxygen uptake (VO2max or peak) presently in use in cardiopulmonary exercise testing (CPET) softwares in Brazil have not been adequately validated. These equations are very important for the diagnostic capacity of this method. Objective Build and validate a Brazilian Equation (BE) for prediction of VO2peak in comparison to the equation cited by Jones (JE) and the Wasserman algorithm (WA). Methods Treadmill evaluation was performed on 3119 individuals with CPET (breath by breath). The construction group (CG) of the equation consisted of 2495 healthy participants. The other 624 individuals were allocated to the external validation group (EVG). At the BE (derived from a multivariate regression model), age, gender, body mass index (BMI) and physical activity level were considered. The same equation was also tested in the EVG. Dispersion graphs and Bland-Altman analyses were built. Results In the CG, the mean age was 42.6 years, 51.5% were male, the average BMI was 27.2, and the physical activity distribution level was: 51.3% sedentary, 44.4% active and 4.3% athletes. An optimal correlation between the BE and the CPET measured VO2peak was observed (0.807). On the other hand, difference came up between the average VO2peak expected by the JE and WA and the CPET measured VO2peak, as well as the one gotten from the BE (p = 0.001). Conclusion BE presents VO2peak values close to those directly measured by CPET, while Jones and Wasserman differ significantly from the real VO2peak. PMID:25352504

  4. Reduced metabolic rate and oxygen radicals production in stored insect sperm.

    PubMed

    Ribou, Anne-Cécile; Reinhardt, Klaus

    2012-06-01

    Females of internally fertilizing species can significantly extend sperm lifespan and functionality during sperm storage. The mechanisms for such delayed cellular senescence remain unknown. Here, we apply current hypotheses of cellular senescence developed for diploid cells to sperm cells, and empirically test opposing predictions on the relationship between sperm metabolic rate and oxygen radical production in an insect model, the cricket Gryllus bimaculatus. Using time-resolved microfluorimetry, we found a negative correlation between metabolic rate (proportion of protein-bound NAD[P]H) and in situ intracellular oxygen radicals production in freshly ejaculated sperm. In contrast, sperm stored by females for periods of 1 h to 26 days showed a positive correlation between metabolic rate and oxygen radicals production. At the same time, stored sperm showed a 37 per cent reduced metabolic rate, and 42 per cent reduced reactive oxygen species (ROS) production, compared with freshly ejaculated sperm. Rank differences between males in ROS production and metabolic rate observed in ejaculated sperm did not predict rank differences in stored sperm. Our method of simultaneously measuring ROS production and metabolic rate of the same sample has the advantage of providing data that are independent of sperm density and any extracellular antioxidants that are proteins. Our method also excludes effects owing to accumulated hydrogen peroxide. Our results unify aspects of competing theories of cellular ageing and suggest that reducing metabolic rate may be an important means of extending stored sperm lifespan and functionality in crickets. Our data also provide a possible explanation for why traits of ejaculates sampled from the male may be rather poor predictors of paternity in sexual selection studies and likelihood of pregnancy in reproductive medicine.

  5. Rate of Biochemical oxygen demand during formation of hypoxia in Amur Bay, Sea of Japan

    NASA Astrophysics Data System (ADS)

    Tishchenko, P. P.; Tishchenko, P. Ya.; Zvalinskii, V. I.; Semkin, P. Yu.

    2014-12-01

    In May 2011, a Water Quality Monitor (WQM) hydrological station was maintained in the hypoxia area of Amur Bay one meter above the bottom, at the depth of 19 m. The temperature, electric conductivity, pressure, and content of dissolved oxygen were registered every four hours for more than three months. On the basis of these data, it was found that the period of hypoxia at the observation point lasted 93 days and a model of calculation of the rate of biochemical oxygen demand and the velocity of ventilation of the bottom waters is suggested.

  6. The effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake

    PubMed Central

    Oh, Deuk-Ja; Hong, Hyeon-Ok; Lee, Bo-Ae

    2016-01-01

    The purpose of this study is to investigate the effects of strenuous exercises on resting heart rate, blood pressure, and maximal oxygen uptake. To achieve the purpose of the study, a total of 30 subjects were selected, including 15 people who performed continued regular exercises and 15 people as the control group. With regard to data processing, the IBM SPSS Statistics ver. 21.0 was used to calculate the mean and standard deviation. The difference of mean change between groups was verified through an independent t-test. As a result, there were significant differences in resting heart rate, maximal heart rate, maximal systolic blood pressure, and maximal oxygen uptake. However, the maximal systolic blood pressure was found to be an exercise-induced high blood pressure. Thus, it is thought that a risk diagnosis for it through a regular exercise stress test is necessary. PMID:26933659

  7. A theoretical model for studying the rate of oxygenation of blood in pulmonary capillaries.

    PubMed

    Singh, M P; Khetarpal, K; Sharan, M

    1980-06-01

    A mathematical analysis of the process of gas exchange in the lung is presented taking into account the transport mechanisms of molecular diffusion, convection and facilitated diffusion of the species due to haemoglobin. Since the rate at which blood gets oxygenated in the pulmonary capillaries is very fast, it is difficult to set up an experimental study to determine the effects of various parameters on equilibration rate. The proposed study is aimed at determining the effects of various physiological parameters on equilibration rate in pathological conditions. Among the significant results are that 1. dissolved oxygen takes longer to achieve equilibration across the pulmonary membrane and carbon dioxide attains equilibration faster, 2. the equilibration length increases with increase in blood velocity, haemoglobin concentration, calibre of pulmonary capillaries and fall in alveolar PO2, 3. the alveolar PCO2 and forward and backward reaction rates of haemoglobin with CO2 do not materially affect the equilibration rate or length. 4. At complete equilibration, by the end of the pulmonary capillary 92% of the total haemoglobin has combined with oxygen and 8% free pigment is left which is present as carbamino haemoglobin, met haemoglobin, carboxy haemoglobin etc. These results are of some importance for anaemic conditions, muscular exercise, meditation, altitude physiology, hypo-ventilation, hyperventilation, etc.

  8. Growth, condition, diet, and consumption rates of northern pike in three Arizona reservoirs

    USGS Publications Warehouse

    Flinders, J.M.; Bonar, Scott A.

    2008-01-01

    Northern pike (Esox lucius L.) introductions are controversial in the western United States due to suspected impacts they might have on established sport fisheries and potential illegal introductions. Tbree Arizona reservoirs, Parker Canyon Lake, Upper Lake Mary and Long Lake were sampled to examine the diet, consumption dynamics, and growth of northern pike. Northern pike diets varied by season and reservoir. In Parker Canyon Lake, diets were dominated by rainbow trout in winter and spring and bluegill and green sunfish in the fall. In Long Lake the northern pike ate crayfish in spring and early summer and switched to young of the year common carp in summer and fall. Black crappie, golden shiners, and crayfish were the major prey in Upper Lake Mary during spring, but they switched to stocked rainbow trout in the fall. Northern pike growth was in the high range of growth reported throughout the United States. Estimated northern pike specific consumption rate (scr) of rainbow trout (g/g/d ?? 10-6) was greatest in Upper Lake Mary (scr = 329.1 ?? 23.7 g/g/d ?? 10-6) where stocked fingerling (280 mm TL) rainbow trout stocked in Long Lake (scr = 1.4 ?? 0.1 g/g/d ?? 10-6) and Parker Canyon Lake (scr = 287.2 ?? 15.1 g/g/d ?? 10-6) where catchable-sized rainbow trout were stocked. Managers should consider the cost-benefits of stocking fish >200 mm TL in lakes containing northern pike. ?? Copyright by the North American Lake Management Society 2008.

  9. Season and application rates affect vaccine bait consumption by prairie dogs in Colorado and Utah, USA

    USGS Publications Warehouse

    Tripp, Daniel W.; Rocke, Tonie E.; Streich, Sean P.; Brown, Nathanael L.; Fernandez, Julia Rodriguez-Ramos; Miller, Michael W.

    2014-01-01

    Plague, a zoonotic disease caused by the bacterium Yersinia pestis, causes high rates of mortality in prairie dogs (Cynomys spp.). An oral vaccine against plague has been developed for prairie dogs along with a palatable bait to deliver vaccine and a biomarker to track bait consumption. We conducted field trials between September 2009 and September 2012 to develop recommendations for bait distribution to deliver plague vaccine to prairie dogs. The objectives were to evaluate the use of the biomarker, rhodamine B, in field settings to compare bait distribution strategies, to compare uptake of baits distributed at different densities, to assess seasonal effects on bait uptake, and to measure bait uptake by nontarget small mammal species. Rhodamine B effectively marked prairie dogs' whiskers during these field trials. To compare bait distribution strategies, we applied baits around active burrows or along transects at densities of 32, 65, and 130 baits/ha. Distributing baits at active burrows or by transect did not affect uptake by prairie dogs. Distributing baits at rates of ≥65/ha (or ≥1 bait/active burrow) produced optimal uptake, and bait uptake by prairie dogs in the autumn was superior to uptake in the spring. Six other species of small mammals consumed baits during these trials. All four species of tested prairie dogs readily consumed the baits, demonstrating that vaccine uptake will not be an obstacle to plague control via oral vaccination.

  10. Season and application rates affect vaccine bait consumption by prairie dogs in Colorado and Utah, USA.

    PubMed

    Tripp, Daniel W; Rocke, Tonie E; Streich, Sean P; Brown, Nathanael L; Fernandez, Julia Rodriguez-Ramos; Miller, Michael W

    2014-04-01

    Plague, a zoonotic disease caused by the bacterium Yersinia pestis, causes high rates of mortality in prairie dogs (Cynomys spp.). An oral vaccine against plague has been developed for prairie dogs along with a palatable bait to deliver vaccine and a biomarker to track bait consumption. We conducted field trials between September 2009 and September 2012 to develop recommendations for bait distribution to deliver plague vaccine to prairie dogs. The objectives were to evaluate the use of the biomarker, rhodamine B, in field settings to compare bait distribution strategies, to compare uptake of baits distributed at different densities, to assess seasonal effects on bait uptake, and to measure bait uptake by nontarget small mammal species. Rhodamine B effectively marked prairie dogs' whiskers during these field trials. To compare bait distribution strategies, we applied baits around active burrows or along transects at densities of 32, 65, and 130 baits/ha. Distributing baits at active burrows or by transect did not affect uptake by prairie dogs. Distributing baits at rates of ≥ 65/ha (or ≥ 1 bait/active burrow) produced optimal uptake, and bait uptake by prairie dogs in the autumn was superior to uptake in the spring. Six other species of small mammals consumed baits during these trials. All four species of tested prairie dogs readily consumed the baits, demonstrating that vaccine uptake will not be an obstacle to plague control via oral vaccination. PMID:24484490

  11. Oxygen ionization rates at Mars and Venus - Relative contributions of impact ionization and charge exchange

    NASA Technical Reports Server (NTRS)

    Zhang, M. H. G.; Luhmann, J. G.; Nagy, A. F.; Spreiter, J. R.; Stahara, S. S.

    1993-01-01

    Oxygen ion production rates above the ionopauses of Venus and Mars are calculated for photoionization, charge exchange, and solar wind electron impact ionization processes. The latter two require the use of the Spreiter and Stahara (1980) gas dynamic model to estimate magnetosheath velocities, densities, and temperatures. The results indicate that impact ionization is the dominant mechanism for the production of O(+) ions at both Venus and Mars. This finding might explain both the high ion escape rates measured by Phobos 2 and the greater mass loading rate inferred for Venus from the bow shock positions.

  12. Oxygen ionization rates at Mars and Venus - Relative contributions of impact ionization and charge exchange

    NASA Astrophysics Data System (ADS)

    Zhang, M. H. G.; Luhmann, J. G.; Nagy, A. F.; Spreiter, J. R.; Stahara, S. S.

    1993-02-01

    Oxygen ion production rates above the ionopauses of Venus and Mars are calculated for photoionization, charge exchange, and solar wind electron impact ionization processes. The latter two require the use of the Spreiter and Stahara (1980) gas dynamic model to estimate magnetosheath velocities, densities, and temperatures. The results indicate that impact ionization is the dominant mechanism for the production of O(+) ions at both Venus and Mars. This finding might explain both the high ion escape rates measured by Phobos 2 and the greater mass loading rate inferred for Venus from the bow shock positions.

  13. Alterations in resting oxygen consumption in women exposed to 10 days of cold air

    SciTech Connect

    Armstrong, D.W.; Thomas, J.R. )

    1991-03-11

    Repeated exposure to cold air reduces the metabolic response to cold air exposure in man. The purpose of this investigation was to measure the change in resting metabolic rate (RMR) with exposure to 22C air and 4C air during a 12 day period. Four women sat in 22C air for 45 min followed by 45 min in 4C air each day for ten days. The authors measured RMR during a 45 min period in 22C air followed by 45 min in 4C air on four days. All subjects began their morning exposures on a Monday within 2 days of the onset of menses completing the study on a Friday, 12 days later. Subjects dressed in a T-shirt, shorts and cotton socks. During 45 min of exposure to warm air, RMR remained steady at 10% of VO{sub 2peak} on Day 1 and 10% on Day 5. RMR during exposure to warm air significantly increased to 13% of VO{sub 2peak} on Day 8 and remained elevated at 13% on Day 12. During exposure to cold air RMR peaked at 31% of CO{sub 2peak} by the 5th min on Day 1. Peak RMR on Day 5 was significantly lower. Pea RMR in the cold remained lower on Days 8 and 12. During cold exposure RMR peaked and then declined to steady-state during min 15 to 45. Steady-state RMR during cold exposure was significantly lower on Day 5, Day 7 and Day 12 when compared to the 23% of VO{sub 2peak} on Day 1. The authors found that RMR in cold air is significantly attenuated by Day 5 and remains lower through Day 12. RMR during warm air exposure is elevated 3% by Day 8 after five (5) days of repeated cold exposure followed by two (2) days without exposure to cold air, and RMR remains elevated on Day 12.

  14. Gene expression profiling reveals decreased expression of two hemoglobin genes associated with increased consumption of oxygen in Chironomus tentans exposed to atrazine: a possible mechanism for adapting to oxygen deficiency.

    PubMed

    Anderson, Troy D; Jin-Clark, Ying; Begum, Khurshida; Starkey, Sharon R; Zhu, Kun Yan

    2008-01-31

    Atrazine is an extensively used triazine herbicide in agricultural and residential areas and has been routinely detected in many surface and ground waters. This study reveals various up- and down-regulated genes associated with hypoxic stress in atrazine-treated fourth-instar Chironomus tentans larvae (midges) by using restriction fragment differential display-PCR. Two down-regulated hemoglobin cDNAs were isolated from the midges. Northern blot analysis indicated CteHb-IIbeta and CteHb-III mRNA expressions decreased by 36 and 21%, respectively, in midges exposed to atrazine at 1 microg/L for 96h. Decreased hemoglobin gene expression was associated with elevated oxygen consumption in atrazine-treated midges. Midges exposed to atrazine at 1 microg/L increased their oxygen consumption by 47%, whereas midges exposed to atrazine at 1000 microg/L for 48h increased their oxygen consumption by 66%. Our study demonstrates for the first time that atrazine, at environmentally relevant concentrations, can elevate respiration, possibly eliciting counteractive measures at the transcriptional level to adapt to oxygen deficiency in an ecologically important aquatic insect. Our results further suggest that the ability to modulate both the quantity and quality of Hb serves as an adaptive response to counteract the initial onset of oxygen deficiency induced by atrazine in midges.

  15. Polymer Growth Rate in a Wire Chamber with Oxygen,Water, or Alcohol Gas Additives

    SciTech Connect

    Boyarski, Adam; /SLAC

    2008-07-02

    The rate of polymer growth on wires was measured in a wire chamber while the chamber was aged initially with helium-isobutane (80:20) gas, and then with either oxygen, water, or alcohol added to the gas. At the completion of the aging process for each gas mixture, the carbon content on the wires was measured in a SEM/EDX instrument. The same physical wires were used in all the gas mixtures, allowing measurement of polymer build up or polymer depletion by each gas additive. It is found that the rate of polymer growth is not changed by the presence of oxygen, water or alcohol. Conjecture that oxygen reduces breakdown by removing polymer deposits on field wires is negated by these measurements. Instead, it appears that the reduced breakdown is due to lower resistance in the polymer from oxygen ions being transported into the polymer. It is also observed that field wires bombarded by the electrons in the SEM and then placed back into the chamber show an abundance of single electrons being emitted, indicating that electron charge is stored in the polymer layer and that a high electric field is necessary to remove the charge.

  16. Automatable Measurement of Gas Exchange Rate in Streams: Oxygen-Carbon Method

    NASA Astrophysics Data System (ADS)

    Pennington, R.; Haggerty, R.; Argerich, A.; Wondzell, S. M.

    2015-12-01

    Gas exchange rates between streams and the atmosphere are critically important to measurement of in-stream ecologic processes, as well as fate and transport of hazardous pollutants such as mercury and PCBs. Methods to estimate gas exchange rates include empirical relations to hydraulics, and direct injection of a tracer gas such as propane or SF6. Empirical relations are inconsistent and inaccurate, particularly for lower order, high-roughness streams. Gas injections are labor-intensive, and measured gas exchange rates are difficult to extrapolate in time since they change with discharge and stream geometry. We propose a novel method for calculation of gas exchange rates utilizing O2, pCO2, pH, and temperature data. Measurements, which can be automated using data loggers and probes, are made on the upstream and downstream end of the study reach. Gas exchange rates are then calculated from a solution to the transport equations for oxygen and dissolved inorganic carbon. Field tests in steep, low order, high roughness streams of the HJ Andrews Experimental Forest indicate the method to be viable along stream reaches with high downstream gas concentration gradients and high rates of gas transfer velocity. Automated and continuous collection of oxygen and carbonate chemistry data is increasingly common, thus the method may be used to estimate gas exchange rates through time, and is well suited for interactivity with databases.

  17. High rate of prey consumption in a small predatory fish on coral reefs

    NASA Astrophysics Data System (ADS)

    Feeney, W. E.; Lönnstedt, O. M.; Bosiger, Y.; Martin, J.; Jones, G. P.; Rowe, R. J.; McCormick, M. I.

    2012-09-01

    Small piscivores are regarded as important regulators of the composition of coral reef fish communities, but few studies have investigated their predatory ecology or impact on assemblages of juvenile fishes. This study investigated the foraging ecology of a common coral reef predator, the dottyback Pseudochromis fuscus, using underwater focal animal observations. Observations were conducted at two times of year: the summer, when recruit fishes were an available food item and winter, when remaining juveniles had outgrown vulnerability to P. fuscus. During the summer, P. fuscus directed 76% of its strikes at invertebrates and 24% at recruiting juvenile fishes. When striking at fishes, P. fuscus exhibited two distinct feeding modes: an ambush (26% successful) and a pursuit mode (5% successful). Predator activity in the field peaked at midday, averaging 2.5 captures h-1 of juvenile fishes. Monitoring of activity and foraging in the laboratory over 24-h periods found that P. fuscus was a diurnal predator and was active for 13 h d-1 during the summer. The number of hours during which foraging was recorded differed greatly among individuals ( n = 10), ranging from 4 to 13 h. The number of predatory strikes did not increase with standard length, but the success rate and consumption rate of juvenile fishes did increase with size. Estimated hourly mortality on juvenile fish ranged from 0.49 fish h-1 in small P. fuscus individuals (30-39 mm standard length, SL; equating to 6.3 per 13 h day) to 2.4 fish h-1 in large P. fuscus individuals (55-65 mm SL; 30.6 per 13 h day). During the winter, P. fuscus struck at invertebrates with a similar rate to the summer period. These observations of the predatory ecology of P. fuscus support the hypothesis that in coral reef systems, small piscivores, because of their high metabolism and activity, are probably important regulators of coral reef fish community composition.

  18. Comparison of Energy Expenditure and Oxygen Consumption of Spontaneous Breathing Trial Conducted With and Without Automatic Tube Compensation

    PubMed Central

    Lago, Alessandra Fabiane; Goncalves, Elaine Cristina; Silva, Elaine Caetano; Menegueti, Mayra Goncalves; Nicolini, Edson Antonio; Auxiliadora-Martins, Maria; Martinez, Edson Zangiacomi; Gastaldi, Ada Clarice; Basile-Filho, Anibal

    2015-01-01

    Background Weaning from mechanical ventilation is defined as the process of release of ventilatory support and how the evaluation of this phase is conducted in the spontaneous breathing trial (SBT). One of the most used modes of SBT is the continuous positive airway pressure (CPAP), which applies a continuous positive pressure in both inspiration and expiration. However, together with the mechanical ventilation modes, the automatic tube compensation (ATC) can be used, which compensates the resistance imposed by the endotracheal tube. The objective of this study was to compare oxygen consumption (VO2) and energy expenditure (EE) during SBT conducted with and without ATC. Methods The study was prospective, randomized and crossover. Forty mechanically ventilated patients were admitted to an intensive care unit of a university tertiary hospital. The participants were randomly allocated in group 1, in which SBT was initiated with CPAP and ATC, followed by CPAP without ATC or in group 2, in which SBT was initiated with CPAP without ATC, followed by CPAP with ATC. Indirect calorimetry helped to measure VO2 and EE during SBT. Results The differences between VO2 and EE obtained during SBT with ATC and without ATC were -1.6 mL/kg/min (95% CI: -4.36 - 1.07) and 5.4 kcal/day (95% CI: -21.67 - 10.79), respectively. Conclusions We concluded that VO2 and EE obtained during SBT with and without ATC were not different. PMID:26251685

  19. Comparison of performance status with peak oxygen consumption in operable patients with non-small-cell lung cancer

    PubMed Central

    ROMAN, Michael A.; KOELWYN, Graeme J.; EVES, Neil D.; HORNSBY, Whitney E.; WATSON, Dorothy; HERNDON, James E.; KOHMAN, Leslie; LOEWEN, Gregory; JONES, Lee W.

    2015-01-01

    Background and objective In this era of increasing options for treatment of ‘surgical’ lung cancer patients, preoperative physiologic assessment of accurate patient selection is becoming more important. The variability in an objective measure of cardiorespiratory fitness (peak oxygen consumption (VO2peak)) across performance in operable non-small-cell lung cancer (NSCLC) patients enrolled in the Cancer and Leukemia Group B trial was compared. Methods Using a cross-sectional design, 392 NSCLC patients underwent an incremental cardiopulmonary cycling exercise test to symptom limitation with expired gas analysis to determine VO2peak. Performance status (PS) was assessed using the Eastern Cooperative Oncology Group (ECOG) tool. Results There was a significant decrease in VO2peak across increasing ECOG categories (P < 0.0001). However, there was a large range in VO2peak for any given ECOG category with overlap between categories (ECOG 0: 5.0–31.5 mL/kg/min; ECOG 1: 4.3–24.8 mL/kg/min; ECOG 2: 8.9–21.9 mL/kg/min; ECOG 3; 3.3–11.7 mL/kg/min). Conclusions PS scoring systems do not provide a sensitive measure of functional status. Objective measures such as VO2peak may be a useful in the clinical management of oncology patients. PMID:23890224

  20. Impact of environmental oxygen, exercise, salinity, and metabolic rate on the uptake and tissue-specific distribution of 17α-ethynylestradiol in the euryhaline teleost Fundulus heteroclitus.

    PubMed

    Blewett, Tamzin A; Robertson, Lisa M; Maclatchy, Deborah L; Wood, Chris M

    2013-08-15

    17α-ethynylestradiol (EE2) is a synthetic estrogen that is an endocrine disruptive toxicant in aquatic environments. The aim of this study was to determine whether metabolic rate influenced EE2 uptake in male killifish (Fundulus heteroclitus), based on the hypothesis that the mechanism of EE2 uptake at the gills is similar to that of oxygen. F. heteroclitus were exposed to 100 ng/L radiolabeled [³H]EE2 for 2 h while swimming at 0, 15, and 40 cm/s. A positive linear correlation between the rates of oxygen consumption (MO₂) and EE2 accumulation was seen (r² = 0.99, p<0.01), with more EE2 taken up at higher swimming speeds, suggesting that oxygen uptake predicts EE2 uptake. EE2 tended to accumulate in the liver (where lipophilic toxicants are metabolized), the gall bladder (where metabolized toxicants enter bile), and the gut (where bile is received). In a subsequent experiment killifish were exposed to both hypoxic and hyperoxic conditions (PO₂=70-80 Torr, and PO₂=400-500 Torr respectively). Despite significant decreases in MO₂ during hypoxia, EE2 uptake rates increased only slightly with hypoxia, but in individual fish there was still a significant correlation between MO₂ and EE2 uptake. This correlation was lost during hyperoxia, and EE2 uptake rates did not change significantly in hyperoxia. Marked influences of salinity on EE2 uptake rate occurred regardless of the oxygen condition, with higher uptake rates in 50% seawater than in freshwater or 100% seawater. Tissue distribution of EE2 in these exposures may have been influenced by changes in tissue blood flow patterns and oxygen supply. These data will be useful in eventually constructing a predictive model to manage the optimal timing for discharge of EE2 from sewage treatment plants into receiving waters.

  1. Effect of dose rate and oxygen on radiation crosslinking of silica filled fluorosilicone rubber

    NASA Astrophysics Data System (ADS)

    Aliev, Roustam

    1999-09-01

    Fluorosilicone (polymethyltrifluoropropylsiloxane) rubber containing silica filler was irradiated with γ-rays and accelerated electrons in air, argon and vacuum. Doses up to 0.5 MGy and dose rates of 1.4 and 10 3 Gy/s were used. The absorbed dose distribution across the rubber thickness during electron irradiation was determined. Oxidation, swelling in ethyl acetate and mechanical properties of this rubber depended on the conditions of irradiation that testified to different effectiveness of the rubber radiation crosslinking under these conditions. Effects of dose rate, diffusion of oxygen into rubber during irradiation, local heating and the oxygen desorption from the filler particles during the electron irradiation are considered for explanation of these differences.

  2. Rate constant for the reaction of atomic oxygen with phosphine at 298 K

    NASA Technical Reports Server (NTRS)

    Stief, L. J.; Payne, W. A.; Nava, D. F.

    1987-01-01

    The rate constant for the reaction of atomic oxygen with phosphine has been measured at 298 K using flash photolysis combined with time-resolved detection of O(3P) via resonance fluorescence. Atomic oxygen was produced by flash photolysis of N2O or NO highly diluted in argon. The results were shown to be independent of (PH3), (O), total pressure and the source of O(3P). The mean value of all the experiments is k1 = (3.6 + or -0.8) x 10 to the -11th cu cm/s (1 sigma). Two previous measurements of k1 differed by more than an order of magnitude, and the results support the higher value obtained in a discharge flow-mass spectrometry study. A comparison with rate data for other atomic and free radical reactions with phosphine is presented, and the role of these reactions in the aeronomy or photochemistry of Jupiter and Saturn is briefly considered.

  3. Reappraisal of diffusion, solubility, and consumption of oxygen in frog skeletal muscle, with applications to muscle energy balance

    PubMed Central

    1985-01-01

    Previously we tested the validity of the one-dimensional diffusion equation for O2 in the excised frog sartorius muscle and used it to measure the diffusion coefficient (D) for O2 in this muscle and the time course of its rate of O2 consumption (Qo2) after a tetanus (Mahler, 1978, 1979, J. Gen. Physiol., 71:533-557, 559-580, 73:159- 174). A transverse section of the frog sartorius is in fact well fit by a hemi-ellipse with width divided by maximum thickness averaging 5.1 +/- 0.2. Using the previous techniques with the two-dimensional diffusion equation and this hemi-elliptical boundary yields a value for D that is 30% smaller than reported previously; the revised values at 0, 10, and 22.8 degrees C are 6.2, 7.9, and 10.8 X 10(-6) cm2/s, respectively. After a tetanus at 20 degrees C, Qo2 rose quickly to a peak and then declined exponentially, with a time constant (tau) approximately 15% faster than that reported previously; tau averaged 2.1 min in Rana temporaria and 2.6 min in Rana pipiens. A technique was devised to measure the solubility (alpha) of O2 in intact, respiring muscles, and yielded alpha (muscle)/alpha (H2O) = 1.26 +/- 0.04. With these modifications, the values for O2 consumption obtained with the diffusion method were in agreement with those measured by the direct method of Kushmerick and Paul (1976, J. Physiol. [Lond.]., 254:693- 709). Using results from both methods, at 20 degrees C the ratio of phosphorylcreatine split during a tetanus to O2 consumption during recovery ranged from 5.2 to 6.2 mumol/mumol, and postcontractile ATP hydrolysis was estimated to be 13.6 +/- 4.1 (n = 3) nmol/mumol total creatine. PMID:4031823

  4. Consumption-leisure tradeoffs in pigeons: Effects of changing marginal wage rates by varying amount of reinforcement.

    PubMed

    Green, L; Kagel, J H; Battalio, R C

    1987-01-01

    Pigeons' rates of responding and food reinforcement under simple random-ratio schedules were compared with those obtained under comparable ratio schedules in which free food deliveries were added, but the duration of each food delivery was halved. These ratio-with-free-food schedules were constructed so that, were the pigeon to maintain the same rate of responding as it had under the simple ratio schedule, total food obtained (earned plus free) would remain unchanged. However, any reduction in responding would reduce total food consumption below that under the simple ratio schedule. These "compensated wage decreases" led to decreases in responding and decreases in food consumption, as predicted by an economic model of labor supply. Moreover, the reductions in responding increased as the ratio value increased (i.e., as wage rates decreased). Pigeons, therefore, substituted leisure for consumption. The relationship between these procedures and negative-income-tax programs is noted. PMID:16812468

  5. Oxygen production rates for P/Halley over much of the 1985-1986 apparition

    NASA Technical Reports Server (NTRS)

    Spinrad, Hyron; Mccarthy, Patrick J.; Strauss, Michael A.

    1986-01-01

    Long slit CCD spectrophotometry of comet P/Halley in the visible region was used to measure the production rate of atomic oxygen during the 1985/86 apparition. The observations cover a large range of heliocentric distances, since the technique is applicable to apparently bright and faint comets. The cometary gas production rate for P/Halley increases rapidly with decreasing heliocentric distance toward perihelion and is systematicaly larger at a given heliocentric distance for the postperihelion observations. The average production rate for O1D on the day of the Giotto flyby is 4 times 10 to the 28th power atoms/sec giving an extrapolated total water production rate of 6 times 10 to the 29th power mols/sec. A method for comparing the absolute cometary gas production rates for different comets is discussed.

  6. Oxygen-Concentrating Cell

    NASA Technical Reports Server (NTRS)

    Buehler, K.

    1986-01-01

    High-purity oxygen produced from breathing air or from propellantgrade oxygen in oxygen-concentrating cell. Operating economics of concentrator attractive: Energy consumption about 4 Wh per liter of oxygen, slightly lower than conventional electrochemical oxygen extractors.

  7. Rates and mechanisms of the atomic oxygen reaction with nickel at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Christian, J. D.; Gilbreath, W. P.

    1973-01-01

    The oxidation of nickel by atomic oxygen at pressure from 1 to 45 N/sq m between 1050 and 1250 K was investigated. In these ranges, the oxidation was found to follow the parobolic rate law, viz., K sub p = 0.0000114 exp(-13410/T) g squared/cm4/sec for films of greater than 1 micron thickness and was pressure independent. The activation enthalpy for the oxidation reaction was 112 + or - 11 kj/mole (27 + or - 3 kcal/mole). Of a number of possible mechanisms and defect structures considered, it was shown that the most likely was a saturated surface defect model for atomic oxidation, based on reaction activation enthalpies, impurity effects, pressure independence, and magnitudes of rates. A model judged somewhat less likely was one having doubly ionized cationic defects rate controlling in both atomic and molecular oxygen. From comparisons of the appropriate processes, the following enthalpy values were derived: enthalpy of activation (Ni diffusion in Ni0) = 110 + or - 30 kj/mole and standard enthalpy change for reaction formation (doubly ionized cation vacancies in Ni0 from atomic oxygen)= -9 + or - 25 kj/mole.

  8. Effects of epinephrine and lactate on the increase in oxygen consumption of non-exercising skeletal muscle after aerobic exercise

    NASA Astrophysics Data System (ADS)

    Murakami, Motohide; Katsumura, Toshihito; Hamaoka, Takatumi; Osada, Takuya; Sako, Takayuki; Higuchi, Hiroyuki; Esaki, Kazuki; Kime, Ryotaro; Shimomitsu, Teruichi

    2000-10-01

    The purpose of this study was to measure O2 consumption of nonexercising skeletal muscles (VO2nonex) at rest and after aerobic exercise and to investigate the stimulant factors of O2 consumption. In experiment 1, we measured the resting metabolic rate of the finger flexor muscles in seven healthy males by 31P-magnetic resonance spectroscopy during a 15 min arterial occlusion. In experiment 2, the VO2nonex of the finger flexor muscles was measured using near infrared continuous wave spectroscopy at rest, immediate postexercise, and 3, 5, 10, 15, and 20 min following a cycling exercise at a workload corresponding to 50% of peak pulmonary O2 uptake for 20 min. We also monitored deep tissue temperature in the VO2nonex measurement area and determined catecholamines and lactate concentrations in the blood at rest and immediate postexercise. VO2nonex at rest was 1.1 +/- 0.1 (mu) M O2/s (mean +/- standard error) and VO2nonex after exercise increased 59.6 +/- 7.2% (p < 0.001) from the resting values. There were significant correlations between the increase in VO2nonex and the increase in epinephrine concentration (p < 0.01), and between the increase in VO2nonex and the increase in lactate concentration (p < 0.05). These results suggest that epinephrine and lactate concentrations are important VO2nonex stimulant factors.

  9. hydrochemistry of the Andeans and sub-andeans Amazon basins - Weathering and CO2 consumption rates.

    NASA Astrophysics Data System (ADS)

    Moquet, Jean-Sébastien; Crave, Alain; Viers, Jérome; Guyot, Jean-Loup; Lagane, Christelle; Sven Lavado Casimiro, Waldo; Pombosa, Rodrigo; Noriega, Luis; Chavary, Eduardo

    2010-05-01

    Measuring mountain weathering rates, estimating their role on C cycle and identifying the parameters which control them are key to better constrain the knowledge of the continental-ocean-atmosphere interactions over geological timescale. The Andes, in contrast to the Himalaya, have received poor attention in terms of chemical weathering. Several authors have worked on the Amazon river basin, but it is difficult to assess the role of the Andes (10% of the surface area of the Amazon river basin) by only sampling the Amazon at mouth or sampling its largest tributaries. As shown by earlier works, the Upper-Amazon basins are the main matter source of the Amazon basin. The studied area participates at more than 70% of the Amazon weathering rates while it contributes to the total discharge on 30% for 27% of the total area. The studied area is comprised between latitude 0°47'N and 20°28'S and between longitude 79°36'W and 58°45'W and can be divided in three major hydrosystems (the Napo river at North, the Maranon-Ucayali rivers on the central part and the upper Madeira at south) which can be separated on Andes and sub-Andes parts. This work presents the results of the HYBAM research program (present-day hydro-geodynamics of the Amazon Basin) on the upper Amazon basin. The concentration of major elements was analyzed on a monthly basis, sampling at 26 gauging stations which include the Andean basins of the Amazon River and a part of the downstream catchment domain. The objectives of this work are i) calculate the major elements fluxes and their spatial distribution, ii) estimate the present-day rate of rock weathering, as well as the flux of atmospheric/soil CO2 consumption from total rock and silicate weathering, and iii) constrain the major environmental factor which controls the dissolved matter production using unique high temporal and spatial resolution data sampling. The main difficulty of studying large river geochemistry is to separate the main sources of the

  10. Fruit, vegetable, and fish consumption and heart rate variability: the Veterans Administration Normative Aging Study123

    PubMed Central

    Tucker, Katherine L; O'Neill, Marie S; Sparrow, David; Vokonas, Pantel S; Hu, Howard; Schwartz, Joel

    2009-01-01

    Background: Higher intakes of fruit, vegetables, and dark fish may prevent sudden cardiac death and arrhythmias, but the exact mechanisms are not fully understood. Objective: We examined whether high consumption of fruit, vegetables, and dark fish would be associated with beneficial changes in heart rate variability (HRV). Design: HRV variables were measured among 586 older men with 928 total observations from November 2000 to June 2007 in the Normative Aging Study, a community-based longitudinal study of aging. Dietary intake was evaluated with a self-administered semiquantitative food-frequency questionnaire and categorized into quartiles. Results: After controlling for potential confounders, intake of green leafy vegetables was positively associated with normalized high-frequency power and inversely associated with normalized low-frequency power (P for trend < 0.05). These significant associations were retained after further adjustment for healthy lifestyle factors, such as physical activity and use of multivitamins. No significant association was seen between HRV measures and intakes of other fruit and vegetables, vitamin C, carotenoids, tuna and dark-meat fish, or n–3 (omega-3) fatty acids. An effect modification of intake of noncitrus fruit by obesity and of total vegetables and cruciferous vegetables by cigarette smoking was seen, which warrants further investigation. Conclusion: These findings suggest that higher intake of green leafy vegetables may reduce the risk of cardiovascular disease through favorable changes in cardiac autonomic function. PMID:19158214

  11. Alcohol Consumption and Abuse among College Students: Alarming Rates among the Best and the Brightest

    ERIC Educational Resources Information Center

    Fuertes, Jairo N.; Hoffman, Alexander

    2016-01-01

    Objective: This study examined alcohol consumption at two college campuses, a "dry" urban campus and a "wet" rural campus. We examined alcohol consumption as a function of students' membership in: Greek Organizations, NCAA Varsity Athletic teams, or as being Unaffiliated in these groups. Participants: Two hundred eighty-eight…

  12. High Oxygen Partial Pressure Decreases Anemia-Induced Heart Rate Increase Equivalent to Transfusion

    PubMed Central

    Feiner, John R.; Finlay-Morreale, Heather E.; Toy, Pearl; Lieberman, Jeremy A.; Viele, Maurene K.; Hopf, Harriet W.; Weiskopf, Richard B.

    2011-01-01

    Background Anemia is associated with morbidity and mortality and frequently leads to transfusion of erythrocytes. We sought to compare directly the effect of high inspired oxygen fraction vs. transfusion of erythrocytes on the anemia-induced increased heart rate (HR) in humans undergoing experimental acute isovolemic anemia. Methods We combined HR data from healthy subjects undergoing experimental isovolemic anemia in seven studies performed by our group. We examined HR changes associated with breathing 100% oxygen by non-rebreathing face mask vs. transfusion of erythrocytes at their nadir hemoglobin (Hb) concentration of 5 g/dL. Data were analyzed using a mixed-effects model. Results HR had an inverse linear relationship to hemoglobin concentration with a mean increase of 3.9 beats per minute per gram of Hb (beats/min/g Hb) decrease (95% confidence interval [CI], 3.7 – 4.1 beats/min/g Hb), P < 0.0001. Return of autologous erythrocytes significantly decreased HR by 5.3 beats/min/g Hb (95% CI, 3.8 – 6.8 beats/min/g Hb) increase, P < 0.0001. HR at nadir Hb of 5.6 g/dL (95% CI, 5.5 – 5.7 g/dL) when breathing air (91.4 beats/min; 95% CI, 87.6 – 95.2 beats/min) was reduced by breathing 100% oxygen (83.0 beats/min; 95% CI, 79.0 -87.0 beats/min), P < 0.0001. The HR at hemoglobin 5.6 g/dL when breathing oxygen was equivalent to the HR at Hb 8.9 g/dL when breathing air. Conclusions High arterial oxygen partial pressure reverses the heart rate response to anemia, probably owing to its usability, rather than its effect on total oxygen content. The benefit of high arterial oxygen partial pressure has significant potential clinical implications for the acute treatment of anemia and results of transfusion trials. PMID:21768873

  13. Cerebral blood flow decreases with time whereas cerebral oxygen consumption remains stable during hypothermic cardiopulmonary bypass in humans

    SciTech Connect

    Prough, D.S.; Rogers, A.T.; Stump, D.A.; Roy, R.C.; Cordell, A.R.; Phipps, J.; Taylor, C.L. )

    1991-02-01

    Recent investigations demonstrate that cerebral blood flow (CBF) progressively declines during hypothermic, nonpulsatile cardiopulmonary bypass (CPB). If CBF declines because of brain cooling, the cerebral metabolic rate for oxygen (CMRO2) should decline in parallel with the reduction in CBF. Therefore we studied the response of CBF, the cerebral arteriovenous oxygen content difference (A-VDcereO2) and CMRO2 as a function of the duration of CPB in humans. To do this, we compared the cerebrovascular response to changes in the PaCO2. Because sequential CBF measurements using xenon 133 (133Xe) clearance must be separated by 15-25 min, we hypothesized that a time-dependent decline in CBF would accentuate the CBF reduction caused by a decrease in PaCO2, but would blunt the CBF increase associated with a rise in PaCO2. We measured CBF in 25 patients and calculated the cerebral arteriovenous oxygen content difference using radial arterial and jugular venous bulb blood samples. Patients were randomly assigned to management within either a lower (32-48 mm Hg) or higher (50-71 mm Hg) range of PaCO2 uncorrected for temperature. Each patient underwent two randomly ordered sets of measurements, one at a lower PaCO2 and the other at a higher PaCO2 within the respective ranges. Cerebrovascular responsiveness to changes in PaCO2 was calculated as specific reactivity (SR), the change in CBF divided by the change in PaCO2, expressed in mL.100 g-1.min-1.mm Hg-1.

  14. Effects of solar cycle variations on oxygen green line emission rate over Kiso, Japan

    NASA Astrophysics Data System (ADS)

    Das, Uma; Pan, C. J.; Sinha, H. S. S.

    2011-08-01

    A sixteen year long dataset of mesospheric OI 557.7 nm green line nightglow emission rate, measured over Kiso (35.79°N, 137.63°E), Japan using ground-based photometers is spectrally investigated using the Hilbert-Huang Transform (HHT). The spectrograms reveal the presence of semi-annual, annual and quasi-biennial oscillations in consonance with the results obtained from wavelet analysis in an earlier study. In addition, due to the use of the HHT, we have been able to investigate the very low frequency solar cycle variation in the emission rate. It is found that there is a significant solar cycle effect on the oxygen green line emission rate. The mean amplitude of variation is approximately 20% and it is also found that it is maximum at midnight. A correlation study between the means of the emission rate and the solar radio flux at 10.7 cm also shows that the effect of solar activity on the oxygen green line emission rate is maximum at midnight.

  15. CRC fuel rating program: road octane performance of oxygenates in 1982 model cars

    SciTech Connect

    Not Available

    1985-07-01

    Because of the widespread interest in the use of alcohols and ethers as gasoline blending components, this program was conducted to evaluate the effects of several oxygenates on gasoline octane performance and to evaluate the effects of car design features such as engine and transmission type. Five oxygenates were evaluated at two nominal concentrations, 5 and 10 volume%, at both regular- and premium-grade octane levels: methanol (MeOH), ethanol (ETOH), isopropanol (IPA), tertiary butanol (TBA), and methyl tertiary butyl ether (MTBE). A blend of 5% MeOH and 5 percent TBA was also tested at both octane levels. Twenty-eight unleaded fuels, including four hydrocarbon fuels, two hydrocarbon fuels plus toluene, and twenty-two oxygenated fuels, were rated in duplicate in thirty-eight cars using the Modified Uniontown Technique (CRC Designation F-28-75 described in Appendix C), plus some additional instructions. All testing was done on chassis dynamometers. Ratings were obtained at full throttle with all thirty-eight cars, and at the most critical part-throttle condition (occurring with manifold vacuum of 4 in. Hg (13.5 kPa) or greater above the full-throttle vacuum) with nine cars.

  16. Thyrotrophin-releasing hormone decreases feeding and increases body temperature, activity and oxygen consumption in Siberian hamsters.

    PubMed

    Schuhler, S; Warner, A; Finney, N; Bennett, G W; Ebling, F J P; Brameld, J M

    2007-04-01

    Thyrotrophin-releasing hormone (TRH) is known to play an important role in the control of food intake and energy metabolism in addition to its actions on the pituitary-thyroid axis. We have previously shown that central administration of TRH decreases food intake in Siberian hamsters. This species is being increasingly used as a physiological rodent model in which to understand hypothalamic control of long-term changes in energy balance because it accumulates fat reserves in long summer photoperiods, and decreases food intake and body weight when exposed to short winter photoperiods. The objectives of our study in Siberian hamsters were: (i) to investigate whether peripheral administration of TRH would mimic the effects of central administration of TRH on food intake and whether these effects would differ dependent upon the ambient photoperiod; (ii) to determine whether TRH would have an effect on energy expenditure; and (iii) to investigate the potential sites of action of TRH. Both peripheral (5-50 mg/kg body weight; i.p.) and central (0.5 microg/ml; i.c.v.) administration of TRH decreased food intake, and increased locomotor activity, body temperature and oxygen consumption in the Siberian hamster, with a rapid onset and short duration of action. Systemic treatment with TRH was equally effective in suppressing feeding regardless of ambient photoperiod. The acute effects of TRH are likely to be centrally mediated and independent of its role in the control of the production of thyroid hormones. We conclude that TRH functions to promote a catabolic energetic state by co-ordinating acute central and chronic peripheral (thyroid-mediated) function.

  17. Comparison across races of peak oxygen consumption and heart failure survival score for selection for cardiac transplantation.

    PubMed

    Goda, Ayumi; Lund, Lars H; Mancini, Donna M

    2010-05-15

    The aim of the present study was to determine whether peak oxygen consumption (VO(2)) and the Heart Failure Survival Score (HFSS) predict prognosis in European-American, African-American, and Hispanic-American patients with chronic heart failure referred for heart transplantation. The peak VO(2) and the HFSS have previously been shown to effectively risk stratify patients with chronic heart failure and are criteria for the listing for heart transplantation. However, the effect of race on the predictive value of these variables has not been studied. A total of 715 patients with congestive heart failure (433 European American, 126 African American, 123 Hispanic American, and 33 other), who had been referred for heart transplantation, underwent cardiopulmonary exercise testing with measurement of the peak VO(2) and calculation of the HFSS. A total of 354 patients had died or undergone urgent heart transplantation or implantation of a left ventricular assist device during the 962 +/- 912 days of follow-up. On univariate and multivariate Cox hazard analysis, both peak VO(2) and the HFSS were powerful prognostic markers in the overall cohort and in the separate races. In the receiver operating characteristic curve analysis, the areas under the curve at 1 and 2 years of follow-up were greater for the HFSS than for peak VO(2). In conclusion, HFSS and peak VO(2) can be used for transplant selection; however, in the era of modern therapy and across races and genders, the HFSS might perform better than the peak VO(2). PMID:20451691

  18. Coffee consumption and cystatin-C-based estimated glomerular filtration rates in healthy young adults: results of a clinical trial.

    PubMed

    Saito, Masafumi; Nemoto, Tohru; Tobimatsu, Satoshi; Ebata, Midori; Le, Yulan; Nakajima, Kei

    2011-01-01

    Recently it has been reported that the estimated glomerular filtration rate (eGFR) is higher in habitual coffee consumers than in noncoffee consumers. However, the causality remains unclear. Therefore, we conducted a clinical trial to investigate the effects of coffee consumption on kidney function. Nineteen asymptomatic nonsmokers aged 21-27 years old participated in this study. They consumed coffee (18 g coffee beans/450 mL per day) or green tea as a comparator for 2 weeks in a crossover design. Although creatinine-based eGFR was not affected after consuming either beverage, all cystatin-C-based eGFRs determined using five different equations were significantly increased after coffee consumption (means: 5.0-7.7%), but not after green tea consumption (means: 0.1-1.6%). Serum adiponectin and magnesium levels increased significantly after coffee consumption (means: 13.6% and 4.3%, resp.), but not after green tea consumption. These findings suggest that even a short period of coffee consumption may increase cystatin-C-based eGFR, along with favorable changes in serum adiponectin, in healthy young adults. PMID:21773013

  19. Trends in cigarette consumption cannot fully explain trends in British lung cancer rates

    PubMed Central

    Lee, P. N.; Forey, B. A.

    1998-01-01

    STUDY OBJECTIVES: To determine whether British lung cancer (LC) trends are adequately explained by cigarette smoking trends, and whether modelling using aggregated smoking prevalence estimates can validly replace modelling using individual smoking histories. METHODS: Observed LC trends for 1955-1985 for both sexes and three age groups were compared with multistage model predictions using smoking history data from two surveys (HALS, AHIP). The modelling used the individual smoking data directly or aggregated prevalence estimates. It allowed for variation in age of starting and stopping smoking, amount smoked, tar levels, and environmental tobacco smoke (ETS) exposure. RESULTS: Observed male LC rates fell faster than predicted by a model (with the first and penultimate stages assumed affected by smoking) that allowed for variation in amount smoked and in tar level (with some provision for "compensation"), and was based on aggregated smoking data from HALS. The discrepancy equated to an annual change unexplained by smoking of -2.4%, -2.8%, and -1.9% for ages 35-44, 45-54, and 55-64. The annual unexplained changes were less in women, and reversed at age 55-64; -1.7%, -0.8%, and +0.8% for the three ages. They were similar using individual smoking histories (-2.6%, -1.8%, and -1.6%; women, - 0.9%, -0.5%, and +0.2%). The discrepancies were unexplained by plausible alternative multistage parameters, full allowance for tar reduction, alternative estimates of amount smoked, or ETS. CONCLUSIONS: British LC trends cannot be fully explained by cigarette consumption trends, implying factors other than cigarette smoking contribute importantly to overall risk. Predictions using aggregated prevalence estimates provide useful information.   PMID:9578854

  20. Cytotoxic effects of 109 reference compounds on rat H4IIE and human HepG2 hepatocytes. III: Mechanistic assays on oxygen consumption with MitoXpress and NAD(P)H production with Alamar Blue™.

    PubMed

    Schoonen, Willem G E J; Stevenson, Joe C R; Westerink, Walter M A; Horbach, G Jean

    2012-04-01

    In vitro toxicity screening can reduce the attrition rate of drug candidates in the pharmaceutical industry in the early development process. The focus in this study is to compare the sensitivity for cytotoxicity of a time-resolved fluoro metric oxygen probe with that of a fluoro metric Alamar Blue™ (AB) assay. Both assays measure mitochondrial activity by either oxygen consumption (LUX-A65N-1 (MitoXpress, Luxcel) probe) or NADH/FADH conversion (AB). Both assays were carried out with increasing concentrations of 109 reference compounds using rat H4IIE and human HepG2 hepatocytes at incubation periods of 24, 48 and 72 h. Prior to this study, the influence on medium with either glucose or galactose was studied to analyze the rate of glycolysis and oxygen consumption, which latter process may be impaired in hepatoma cells. Inhibitors of oxygen consumption in combination with a glucose up-take inhibitor showed the largest consumption rate differences in the presence of 5mM of glucose. The choice for the 109 reference compounds was based on the so-called Multicentre Evaluation for In vitro Cytotoxicity (MEIC) and on diverse drug categories. For 59 toxic reference compounds, an evaluation for both assays was carried up to 10(-3)M. Toxicity was demonstrated with MitoXpress for 23 (39%) and 36 (61%) compounds in H4IIE and HepG2 cells, respectively, and with AB for 44 (75%) and 40 (68%) compounds. For 50 more pharmaceutical drugs more physiological concentrations were used up to 3.16×10(-5)M, and only 19 (38%) of these compounds appeared to be toxic in both assays. In conclusion, overall 63 (58%) and 60 (55%) compounds showed toxic effects with the MitoXpress and AB assays on rat H4IIE and human HepG2 hepatocytes, respectively. AB assays were more sensitive with respect to H4IIE cells and MitoXpress assays with respect to HepG2 cells. At all tested time intervals, MitoXpress showed its sensitivity, while AB is more sensitive at 48 and 72 h. With AB more toxic compounds

  1. Heart rate variability of human in hypoxic oxygen-argon environment

    NASA Astrophysics Data System (ADS)

    Khayrullina, Rezeda; Smoleevskiy, Alexandr; Bubeev, Yuri

    Human adaptive capacity, reliability and stability in extreme environments depend primarily on the individual resistance to stresses, includes both innate and acquired components. We have conducted studies in six healthy subjects - men aged between 24 to 42 years who psychophysiological indicators acterizing the severity of stress reactions studied directly during an emergency situation, before and after it. The subjects were in a hypoxic oxygen-argon atmosphere 10 days. Cardiovascular system is one of the first to respond to stressful reaction. The method of heart rate variability (HRV) allows us to estimate balance of sympathetic and parasympathetic parts of vegetative nervous system. In the course of the baseline study it was found that resting heart rate (HR) in the examined individuals is within normal limits. During the experiment in all subjects there was a trend towards more frequent heartbeat. Each subject at one stage or another stay in a hypoxic oxygen-argon environment heart rate go beyond the group norm, but the extent and duration of these abnormalities were significantly different. Marked increase in middle heart rate during of subjects experiment, fluctuating within a wide range (from 2.3% to 29.1%). Marked increase in middle heart rate during of subjects experiment, fluctuating within a wide range (from 2.3% to 29.1%). This suggests that the ability to adapt to living in the investigated gas environment have marked individual differences. SDNN (mean square deviation of all R-R intervals) is the integral indicator of the total effect of the sinus node to the sympathetic and parasympathetic parts of vegetative nervous system, as well as indicating the higher functional reserves of the cardiovascular systems. Increase in heart rate in the majority of subject was accompanied by an increase in individual SDNN. This suggests that the parasympathetic system is able to balance the increase in activity of the sympathetic system, and functional reserves are

  2. Influence of Prolonged Spaceflight on Heart Rate and Oxygen Uptake Kinetics

    NASA Astrophysics Data System (ADS)

    Hoffmann, U.; Moore, A.; Drescher, U.

    2013-02-01

    During prolonged spaceflight, physical training is used to minimize cardiovascular deconditioning. Measurement of the kinetics of cardiorespiratory parameters, in particular the kinetic analysis of heart rate, respiratory and muscular oxygen uptake, provides useful information with regard to the efficiency and regulation of the cardiorespiratory system. Practically, oxygen uptake kinetics can only be measured at the lung site (V’O2 resp). The dynamics of V’O2 resp, however, is not identical with the dynamics at the site of interest: skeletal muscle. Eight Astronauts were tested pre- and post-flight using pseudo random binary workload changes between 30 and 80 W. Their kinetic responses of heart rate, respiratory as well as muscular V’O2 kinetics were estimated by using time-series analysis. Statistical analysis revealed that the kinetic responses of respiratory as well as muscular V’O2 kinetics are slowed post-flight than pre-flight. Heart rate seems not to be influenced following flight. The influence of other factors (e. g. astronauts’ exercise training) may impact these parameters and is an area for future studies.

  3. Direct spectroscopic observation of singlet oxygen quenching and kinetic studies of physical and chemical singlet oxygen quenching rate constants of synthetic antioxidants (BHA, BHT, and TBHQ) in methanol.

    PubMed

    Lee, Jun Hyun; Jung, Mun Yhung

    2010-08-01

    Singlet oxygen quenching by synthetic antioxidants (BHA, BHT, and TBHQ) was directly observed by spectroscopic monitoring of luminescence at 1268 nm. The luminescence data showed unambiguous evidence of singlet oxygen quenching by synthetic phenolic antioxidants with the highest activity for TBHQ, followed by BHA and BHT. The protective activities of these synthetic antioxidants on alpha-terpinene oxidation with chemically-induced singlet oxygen under dark further confirmed their singlet oxygen quenching abilities. Total singlet oxygen quenching rate constants (k(r) + k(q)) of BHA, BHT, and TBHQ were determined in a system containing alpha-terpinene (as a singlet oxygen trap) and methylene blue (as a sensitizer) during light irradiation, and the values were 5.14 x 10(7), 3.41 x 10(6), and 1.99 x 10(8) M(-1)s(-1), respectively. After the k(r) value of alpha-terpinene was first determined, the k(r) values of the synthetic antioxidants were calculated by measuring their relative reaction rates with singlet oxygen to that of alpha-terpinene under the identical conditions. The k(r) values of the BHA, BHT, and TBHQ were 3.90 x 10(5), 1.23 x 10(5), and 2.93 x 10(6), M(-1)s(-1). The percent partition of chemical quenching over total singlet oxygen quenching (k(r) x 100)/(k(r) + k(q)) for BHA, BHT, and TBHQ were 0.76%, 3.61%, and 1.47%, respectively. The results showed that the synthetic antioxidants quench singlet oxygen almost exclusively through the mechanism of physical quenching. This represents the first report on the singlet oxygen quenching mechanism of these synthetic antioxidants. Practical Application: The synthetic antioxidants, especially TBHQ, have been found to have a strong singlet oxygen quenching ability. This article also clearly showed that singlet oxygen quenching by synthetic antioxidants was mainly by the physical quenching mechanism. The results suggested that these synthetic antioxidants, especially TBHQ, could be used practically for the protection

  4. On the structure and oxygen transmission rate of biodegradable cellulose nanobarriers

    NASA Astrophysics Data System (ADS)

    Chinga-Carrasco, Gary; Syverud, Kristin

    2012-03-01

    Cellulose nanofibrils have been proposed for novel barrier concepts, based on their capability to form smooth, strong and transparent films, with high oxygen barrier properties. A series of cellulose-based films were manufactured and tested with respect to their oxygen transmission rate (OTR) capabilities. The obtained OTR levels were considerably better than the levels recommended for packaging applications. Part of the nanofibrillated material applied in this study was produced with 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) mediated oxidation as pretreatment. Films made of TEMPO-pretreated samples yielded lower OTR values. The minimum obtained OTR value was 3.0 mL m-2 day-1 atm-1 with a corresponding oxygen permeability of 0.04 mL mm m-2 day-1 atm-1, tested at 50% relative humidity. The good barrier properties are due to the compact and dense structure of the films, as revealed by field-emission scanning electron microscopy. A relationship between OTR and the structure of the corresponding nanofibril-based films was confirmed.

  5. Spatiotemporal dynamics of phosphorus release, oxygen consumption and greenhouse gas emissions after localised soil amendment with organic fertilisers.

    PubMed

    Christel, Wibke; Zhu, Kun; Hoefer, Christoph; Kreuzeder, Andreas; Santner, Jakob; Bruun, Sander; Magid, Jakob; Jensen, Lars Stoumann

    2016-06-01

    Organic fertilisation inevitably leads to heterogeneous distribution of organic matter and nutrients in soil, i.e. due to uneven surface spreading or inhomogeneous incorporation. The resulting localised hotspots of nutrient application will induce various biotic and abiotic nutrient turnover processes and fixation in the residue sphere, giving rise to distinct differences in nutrient availability, soil oxygen content and greenhouse gas (GHG) production. In this study we investigated the spatiotemporal dynamics of the reaction of manure solids and manure solids char with soil, focusing on their phosphorus (P) availability, as current emphasis on improving societal P efficiency through recycling waste or bio-based fertilisers necessitates a sound understanding of their behaviour. Soil layers amended at a constant P application rate with either pig manure solids or char made from pig manure solids were incubated for three weeks between layers of non-amended, P-depleted soil. Spatial and temporal changes in and around the amendment layers were simultaneously investigated in this study using a sandwich sensor consisting of a planar oxygen optode and multi-element diffusive gradients in thin films (DGT) gels, combined with GHG emission measurements. After three weeks of incubation, the soil containing a layer amended with manure solids had a lower overall O2 content and had emitted significantly more CO2 than the non-amended control or the char-amended soil. The P availability from manure solids was initially higher than that from the char, but decreased over time, whereas from the char-amended layer P availability increased in the same period. In both treatments, increases in P availability were confined to the amended soil layer and did not greatly affect P availability in the directly adjacent soil layers during the three-week incubation. These results highlight the importance of placing organic P fertilisers close to where the plant roots will grow in order to

  6. Spatiotemporal dynamics of phosphorus release, oxygen consumption and greenhouse gas emissions after localised soil amendment with organic fertilisers.

    PubMed

    Christel, Wibke; Zhu, Kun; Hoefer, Christoph; Kreuzeder, Andreas; Santner, Jakob; Bruun, Sander; Magid, Jakob; Jensen, Lars Stoumann

    2016-06-01

    Organic fertilisation inevitably leads to heterogeneous distribution of organic matter and nutrients in soil, i.e. due to uneven surface spreading or inhomogeneous incorporation. The resulting localised hotspots of nutrient application will induce various biotic and abiotic nutrient turnover processes and fixation in the residue sphere, giving rise to distinct differences in nutrient availability, soil oxygen content and greenhouse gas (GHG) production. In this study we investigated the spatiotemporal dynamics of the reaction of manure solids and manure solids char with soil, focusing on their phosphorus (P) availability, as current emphasis on improving societal P efficiency through recycling waste or bio-based fertilisers necessitates a sound understanding of their behaviour. Soil layers amended at a constant P application rate with either pig manure solids or char made from pig manure solids were incubated for three weeks between layers of non-amended, P-depleted soil. Spatial and temporal changes in and around the amendment layers were simultaneously investigated in this study using a sandwich sensor consisting of a planar oxygen optode and multi-element diffusive gradients in thin films (DGT) gels, combined with GHG emission measurements. After three weeks of incubation, the soil containing a layer amended with manure solids had a lower overall O2 content and had emitted significantly more CO2 than the non-amended control or the char-amended soil. The P availability from manure solids was initially higher than that from the char, but decreased over time, whereas from the char-amended layer P availability increased in the same period. In both treatments, increases in P availability were confined to the amended soil layer and did not greatly affect P availability in the directly adjacent soil layers during the three-week incubation. These results highlight the importance of placing organic P fertilisers close to where the plant roots will grow in order to

  7. Diurnal dynamics of oxygen and carbon dioxide concentrations in shoots and rhizomes of a perennial in a constructed wetland indicate down-regulation of below ground oxygen consumption

    PubMed Central

    Faußer, Anna C.; Dušek, Jiří; Čížková, Hana; Kazda, Marian

    2016-01-01

    Wetland plants actively provide oxygen for aerobic processes in submerged tissues and the rhizosphere. The novel concomitant assessment of diurnal dynamics of oxygen and carbon dioxide concentrations under field conditions tests the whole-system interactions in plant-internal gas exchange and regulation. Oxygen concentrations ([O2]) were monitored in-situ in central culm and rhizome pith cavities of common reed (Phragmites australis) using optical oxygen sensors. The corresponding carbon dioxide concentrations ([CO2]) were assessed via gas samples from the culms. Highly dynamic diurnal courses of [O2] were recorded, which started at 6.5–13 % in the morning, increased rapidly up to 22 % during midday and declined exponentially during the night. Internal [CO2] were high in the morning (1.55–17.5 %) and decreased (0.04–0.94 %) during the rapid increase of [O2] in the culms. The observed negative correlations between [O2] and [CO2] particularly describe the below ground relationship between plant-mediated oxygen supply and oxygen use by respiration and biogeochemical processes in the rhizosphere. Furthermore, the nocturnal declining slopes of [O2] in culms and rhizomes indicated a down-regulation of the demand for oxygen in the complete below ground plant-associated system. These findings emphasize the need for measurements of plant-internal gas exchange processes under field conditions because it considers the complex interactions in the oxic-anoxic interface. PMID:27207278

  8. Diurnal dynamics of oxygen and carbon dioxide concentrations in shoots and rhizomes of a perennial in a constructed wetland indicate down-regulation of below ground oxygen consumption.

    PubMed

    Faußer, Anna C; Dušek, Jiří; Čížková, Hana; Kazda, Marian

    2016-01-01

    Wetland plants actively provide oxygen for aerobic processes in submerged tissues and the rhizosphere. The novel concomitant assessment of diurnal dynamics of oxygen and carbon dioxide concentrations under field conditions tests the whole-system interactions in plant-internal gas exchange and regulation. Oxygen concentrations ([O2]) were monitored in-situ in central culm and rhizome pith cavities of common reed (Phragmites australis) using optical oxygen sensors. The corresponding carbon dioxide concentrations ([CO2]) were assessed via gas samples from the culms. Highly dynamic diurnal courses of [O2] were recorded, which started at 6.5-13 % in the morning, increased rapidly up to 22 % during midday and declined exponentially during the night. Internal [CO2] were high in the morning (1.55-17.5 %) and decreased (0.04-0.94 %) during the rapid increase of [O2] in the culms. The observed negative correlations between [O2] and [CO2] particularly describe the below ground relationship between plant-mediated oxygen supply and oxygen use by respiration and biogeochemical processes in the rhizosphere. Furthermore, the nocturnal declining slopes of [O2] in culms and rhizomes indicated a down-regulation of the demand for oxygen in the complete below ground plant-associated system. These findings emphasize the need for measurements of plant-internal gas exchange processes under field conditions because it considers the complex interactions in the oxic-anoxic interface. PMID:27207278

  9. Calculation: Values and Consumption Rates of Locally Produced Food and Tap Water for the Receptor of Interest

    SciTech Connect

    J. Bland

    2000-07-31

    This calculation produces standard statistical data on the consumption of locally produced food and tap water. The results of this calculation provide input parameters for the GENII-S (Leigh et al. 1993) computer code to support calculation of Biosphere Dose Conversion Factors (BDCF) for the nominal performance (groundwater contamination) scenario and the volcanic eruption (contamination of soil by volcanic ash deposition) scenario. The requirement and parameters for these data are identified in ''Identification Of The Critical Group (Consumption Of Locally Produced Food And Tap Water)'' (CRWMS M&O 2000a). This calculation is performed in accordance with the ''Development Plan for Calculation: Values and Consumption Rates of Locally Produced Food and Tap Water for the Receptor of Interest'' (CRWMS M&O 2000b).

  10. Drivers of summer oxygen depletion in the central North Sea

    NASA Astrophysics Data System (ADS)

    Queste, B. Y.; Fernand, L.; Jickells, T. D.; Heywood, K. J.; Hind, A. J.

    2015-06-01

    In stratified shelf seas, oxygen depletion beneath the thermocline is a result of a greater rate of biological oxygen demand than the rate of supply of oxygenated water. Suitably equipped gliders are uniquely placed to observe both the supply through the thermocline and the consumption of oxygen in the bottom layers. A Seaglider was deployed in the shallow (≈ 100 m) stratified North Sea in a region of known low oxygen during August 2011 to investigate the processes regulating supply and consumption of dissolved oxygen below the pycnocline. The first deployment of such a device in this area, it provided extremely high resolution observations, 316 profiles (every 16 min, vertical resolution of 1 m) of CTD, dissolved oxygen concentrations, backscatter and fluorescence during a three day deployment. The high temporal resolution observations revealed occasional small scale events that supply oxygenated water into the bottom layer at a rate of 2±1 μmol dm-3 day-1. Benthic and pelagic oxygen sinks, quantified through glider observations and past studies, indicate more gradual background consumption rates of 2.5±1 μmol dm-3 day-1. This budget revealed that the balance of oxygen supply and demand is in agreement with previous studies of the North Sea. However, the glider data show a net oxygen consumption rate of 2.8±0.3 μmol dm-3 day-1 indicating a localised or short-lived increase in oxygen consumption rates. This high rate of oxygen consumption is indicative of an unidentified oxygen sink. We propose that this elevated oxygen consumption is linked to localised depocentres and rapid remineralisation of resuspensded organic matter. The glider proved to be an excellent tool for monitoring shelf sea processes despite challenges to glider flight posed by high tidal velocities, shallow bathymetry, and very strong density gradients. The direct observation of these processes allows more up to date rates to be used in the development of ecosystem models.

  11. ATP Consumption by SR Ca2+ Pumps Accounts for 50% of Resting Metabolic Rate in Mouse Fast and Slow Twitch Skeletal Muscle

    PubMed Central

    Norris, Sarah Michelle; Bombardier, Eric; Smith, Ian Curtis; Vigna, Chris; Tupling, Allan Russell

    2010-01-01

    The purpose of this study was to directly quantify the relative contribution of Ca2+ cycling to resting metabolic rate in mouse fast (extensor digitorum longus, EDL) and slow (soleus, SOL) twitch skeletal muscle. Resting oxygen consumption of isolated muscles (VO2, μL/g wet weight/s) measured polarographically at 30°C was ~25% higher in SOL (0.61 ± .03) than EDL (0.46 ± .03). In order to quantify the specific contribution of Ca2+ cycling to resting metabolic rate, cyclopiazonic acid (CPA), a highly specific inhibitor of sarco(endo)plasmic Ca2+ ATPases (SERCAs), was added to the bath at different concentrations (1, 5, 10 and 15 μM). There was a concentration-dependent effect of CPA on oxygen consumption with increasing CPA concentrations up to 10 μM resulting in progressively greater reductions in muscle VO2. There were no differences between 10 and 15 μM CPA indicating that 10 μM CPA induces maximal inhibition of SERCAs in isolated muscle preparations. The relative (%) reduction in muscle VO2 in response to CPA was nearly identical in EDL (1 μM, 10.6 ± 3.0; 5 μM, 33.2 ± 3.4; 10 μM, 49.2 ± 2.9; 15 μM, 50.9 ± 2.1) and SOL (1 μM, 11.2 ± 1.5; 5 μM, 37.7 ± 2.4; 10 μM, 50.0 ± 1.3; 15 μM, 49.9 ± 1.6). The results indicate that ATP consumption by SERCAs is responsible for ~50% of resting metabolic rate in both mouse fast- and slow-twitch muscles at 30°C. Thus, SERCA pumps in skeletal muscle could represent an important control point for energy balance regulation and a potential target for metabolic alterations to oppose obesity. PMID:20018953

  12. Modular continuous wavelet processing of biosignals: extracting heart rate and oxygen saturation from a video signal

    PubMed Central

    2016-01-01

    A novel method of extracting heart rate and oxygen saturation from a video-based biosignal is described. The method comprises a novel modular continuous wavelet transform approach which includes: performing the transform, undertaking running wavelet archetyping to enhance the pulse information, extraction of the pulse ridge time–frequency information [and thus a heart rate (HRvid) signal], creation of a wavelet ratio surface, projection of the pulse ridge onto the ratio surface to determine the ratio of ratios from which a saturation trending signal is derived, and calibrating this signal to provide an absolute saturation signal (SvidO2). The method is illustrated through its application to a video photoplethysmogram acquired during a porcine model of acute desaturation. The modular continuous wavelet transform-based approach is advocated by the author as a powerful methodology to deal with noisy, non-stationary biosignals in general. PMID:27382479

  13. Modular continuous wavelet processing of biosignals: extracting heart rate and oxygen saturation from a video signal.

    PubMed

    Addison, Paul S

    2016-06-01

    A novel method of extracting heart rate and oxygen saturation from a video-based biosignal is described. The method comprises a novel modular continuous wavelet transform approach which includes: performing the transform, undertaking running wavelet archetyping to enhance the pulse information, extraction of the pulse ridge time-frequency information [and thus a heart rate (HRvid) signal], creation of a wavelet ratio surface, projection of the pulse ridge onto the ratio surface to determine the ratio of ratios from which a saturation trending signal is derived, and calibrating this signal to provide an absolute saturation signal (SvidO2). The method is illustrated through its application to a video photoplethysmogram acquired during a porcine model of acute desaturation. The modular continuous wavelet transform-based approach is advocated by the author as a powerful methodology to deal with noisy, non-stationary biosignals in general. PMID:27382479

  14. Acclimatization to altitude: effects on arterial oxygen saturation and pulse rate during prolonged exercise at altitude.

    PubMed

    Stoneham, M D; Pethybridge, R J

    1993-01-01

    Changes in the arterial haemoglobin-oxygen saturation (SaO2) of the blood, in the blood pressure and in the heart rate, were monitored in subjects performing static exercise at an altitude of 3,600 metres before and after an acclimatization period of 28 days during an expedition to the Bolivian Andes. It was found that acclimatised subjects could maintain their SaO2 during prolonged exercise better than non-acclimatised subjects. The pulse rate of acclimatised subjects was consistently lower at the same work level than that of non-acclimatised subjects. Acclimatised subjects were able to reach higher levels of exercise than when they had first arrived at altitude. These data imply that acclimatization to altitude improves the delivery of oxygen to the tissues. The mechanism of this is not certain, but it may be concerned with a reduction in the degree of ventilation-perfusion inequality of the lung which occurs on exposure to high altitude.

  15. Development, consumption rates and reproductive biology of Orius albidipennis reared on various prey

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The reproductive biology and feeding consumption of Orius albidipennis fed on eggs of Anagasta (Ephestia) kuehniella, Tetranychus urticae, and Trialeurodes vaporariorum, and larvae of Gynaikothrips ficorum were investigated under 26±1°C, 60±10 % RH and 16:8 L/D photoperiod in laboratory. Results ind...

  16. [Effect of oxygen on the growth, respiratory rate and morphology of Candida utilis cells in periodic and continuous cultures].

    PubMed

    Vorob'eva, G S; Filonenko, N N

    1982-01-01

    The aim of this work was to study how the concentration of oxygen dissolved in the cultural broth influenced the respiration and morphology of the yeast Candida utilis in batch and continuous cultures. Highly effective respiration was registered in cells growing for a certain period of time at low oxygen concentrations limiting the growth; the respiration was characterized by low values of the Michaelis constant kc and the critical concentration of dissolved oxygen Ccr. When passing from the low oxygen concentration to a high one, the character of cellular respiration changed abruptly in the cells whose growth was limited with oxygen for a long time. The morphology of the culture limited with oxygen was characterized by an increase in the percentage of elongated forms in the population. The respiration of the cells cultivated at high oxygen concentrations, when their growth was either non-limited or limited by glucose, was distinguished by high Ccr values and slow respiration rates at small oxygen concentrations while the dependence of the respiration rate on the concentration of oxygen had an about S-shaped character.

  17. Water has no effect on oxygen self-diffusion rate in forsterite

    NASA Astrophysics Data System (ADS)

    Fei, H.; Yamazaki, D.; Wiedenbeck, M.; Katsura, T.

    2014-12-01

    Water is thought to play an essential role in dynamical processes in the Earth's interior. Even several tens wt. ppm of water may enhance the creep rates in olivine by orders of magnitude based on deformation experiments [1, 2]. High temperature creep in olivine is believed to be controlled by self-diffusion of the slowest species, which is silicon in olivine. However, silicon self-diffusion experiments suggest that the role of water on olivine rheology is overestimated in previous deformation studies because of the experimental difficulties [3].On the other hand, oxygen is the second slowest species with similar diffusion rate as silicon. It may also play an essential role in olivine creep. By comparing the oxygen self-diffusion coefficient (DO) in olivine at ambient pressure and dry conditions [4] with those at 2 GPa and hydrous conditions, it is found that even 30-50 wt. ppm of water could enhance DO by one order of magnitude [5]. However, comparison of experimental results obtained at different pressures could lead to misinterpretations because different experimental setups have different error sources [6]. In this study, we systematically measured DO in an iron-free olivine, namely, forsterite, at 8 GPa and 1600-1800 K over a wide range of water content (CH2O) from <1 up to 800 wt. ppm. Our results show that DO∝(CH2O)0.05±0.06≈(CH2O)0. Thus, water has no significant effect on oxygen self-diffusion rate in forsterite. Since the water content dependence of silicon self-diffusion rate is also very small [3], the role of water on olivine rheology is not as significant as previously thought by assuming the diffusion controlled creep mechanism. [1] Karato &Jung (2003), Philosophical Mag. 83, 401-414.[2] Hirth & Kohlstedt (2003) Geophys. Monogr. 138, 83-105.[3] Fei et al. (2013), Nature 498, 213-215.[4] Dohmen et al. (2002), GRL 29, 2030.[5] Costa & Chakraborty (2008), PEPI 166, 11-29.[6] Fei et al. (2012), EPSL 345, 95-103.

  18. Temperature and Atomic Oxygen Effects on Helium Leak Rates of a Candidate Main Interface Seal

    NASA Technical Reports Server (NTRS)

    Penney, Nicholas; Wasowski, Janice L.; Daniels, Christopher C.

    2011-01-01

    Helium leak tests were completed to characterize the leak rate of a 54 in. diameter composite space docking seal design in support of the National Aeronautics and Space Administration s (NASA's) Low Impact Docking System (LIDS). The evaluated seal design was a candidate for the main interface seal on the LIDS, which would be compressed between two vehicles, while docked, to prevent the escape of breathable air from the vehicles and into the vacuum of space. Leak tests completed at nominal temperatures of -30, 20, and 50 C on untreated and atomic oxygen (AO) exposed test samples were examined to determine the influence of both test temperature and AO exposure on the performance of the composite seal assembly. Results obtained for untreated seal samples showed leak rates which increased with increased test temperature. This general trend was not observed in tests of the AO exposed specimens. Initial examination of collected test data suggested that AO exposure resulted in higher helium leak rates, however, further analysis showed that the differences observed in the 20 and 50 C tests between the untreated and AO exposed samples were within the experimental error of the test method. Lack of discernable trends in the test data prevented concrete conclusions about the effects of test temperature and AO exposure on helium leak rates of the candidate seal design from being drawn. To facilitate a comparison of the current test data with results from previous leak tests using air as the test fluid, helium leak rates were converted to air leak rates using standard conversion factors for viscous and molecular flow. Flow rates calculated using the viscous flow conversion factor were significantly higher than the experimental air leakage values, whereas values calculated using the molecular flow conversion factor were significantly lower than the experimentally obtained air leak rates. The difference in these sets of converted flow rates and their deviation from the

  19. Comparison of Estimations Versus Measured Oxygen Consumption at Rest in Patients With Heart Failure and Reduced Ejection Fraction Who Underwent Right-Sided Heart Catheterization.

    PubMed

    Chase, Paul J; Davis, Paul G; Wideman, Laurie; Starnes, Joseph W; Schulz, Mark R; Bensimhon, Daniel R

    2015-12-01

    Cardiac output during right-sided heart catheterization is an important variable for patient selection of advanced therapies (cardiac transplantation and left ventricular assist device implantation). The Fick method to determine cardiac output is commonly used and typically uses estimated oxygen consumption (VO2) from 1 of 3 published empirical formulas. However, these estimation equations have not been validated in patients with heart failure and reduced ejection fraction (HFrEF). The objectives of the present study were to determine the accuracy of 3 equations for estimating VO2 compared with direct measurement of VO2 and determine the extent clinically significant error occurred in calculating cardiac output of patients with HFrEF. Breath-by-breath measurements of VO2 from 44 patients who underwent cardiac catheterization (66% men; age, 65 ± 11 years, left ventricular ejection fraction, 22 ± 6%) were compared with the derived estimations of LaFarge and Miettinen, Dehmer et al, and Bergstra et al. Single-sample t tests found only the mean difference between the estimation of LaFarge and Miettinen and the measured VO2 to be nonsignificant (-10.3 ml/min ± 6.2 SE, p = 0.053). Bland-Altman plots demonstrated unacceptably large limits of agreement for all equations. The rate of ≥25% error in the equations by LaFarge and Miettinen, Dehmer et al, and Bergstra et al occurred in 11%, 23%, and 45% of patients, respectively. Misclassification of cardiac index derived from each equation for 2 clinically important classifications: cardiogenic shock-21%, 23%, and 32% and hypoperfusion-16%, 16%, and 25%; respectively. In conclusion, these findings do not support the use of these empiric formulas to estimate the VO2 at rest in patients with HFrEF who underwent right-sided heart catheterization.

  20. Global rate coefficients for ionization and recombination of carbon, nitrogen, oxygen, and argon

    SciTech Connect

    Annaloro, Julien; Morel, Vincent; Bultel, Arnaud; Omaly, Pierre

    2012-07-15

    The flow field modeling of planetary entry plasmas, laser-induced plasmas, inductively coupled plasmas, arcjets, etc., requires to use Navier-Stokes codes. The kinetic mechanisms implemented in these codes involve global (effective) rate coefficients. These rate coefficients result from the excited states coupling during a quasi-steady state. In order to obtain these global rate coefficients over a wide electron temperature (T{sub e}) range for ionization and recombination of carbon, nitrogen, oxygen, and argon, the behavior of their excited states is investigated using a zero-dimensional (time-dependent) code. The population number densities of these electronic states are considered as independent species. Their relaxation is studied within the range 3000 K{<=}T{sub e}{<=}20 000 K and leads to the determination of the ionization (k{sub i}) and recombination (k{sub r}) global rate coefficients. Comparisons with existing data are performed. Finally, the ratio k{sub i}/k{sub r} is compared with the Saha equilibrium constant. This ratio increases more rapidly than the equilibrium constant for T{sub e}>15 000 K.

  1. Consumption rate of some proteinic diets affecting hypopharyngeal glands development in honeybee workers

    PubMed Central

    Al-Ghamdi, Ahmad AlKazim; Al-Khaibari, Abeer M.; Omar, Mohamed O.

    2010-01-01

    The experiment was carried out under laboratory condition to study the consumption of some proteinic diets and their effect on hypopharyngeal glands (HPG) development during nursing period. The results showed that the bee bread and the pollen loads mixture with sugar (1:1) were more consumed by honeybee workers followed by Nectapol® and Yeast-Gluten mixture. The lowest consumption amount was recorded with traditional substitute. Clear differences were found in HPG development under feeding with different diets. The maximum development degree was observed when fed with bee bread followed by pollen loads and mixture from Yeast, Gluten and sugar (1:1:2). The acinal surface of HPG showed clear difference under feeding with difference diets. The largest area was recorded when honeybee workers fed on bee bread followed by Yeast-Gluten-sugar mixture (diet,4) and pollen loads(diet,2). PMID:23961106

  2. Parasitoid wasps indirectly suppress seed production by stimulating consumption rates of their seed-feeding hosts.

    PubMed

    Xi, Xinqiang; Eisenhauer, Nico; Sun, Shucun

    2015-07-01

    In parasitoid-herbivore-plant food chains, parasitoids may be simultaneously linked with both herbivore hosts and plants, as occurs when herbivores attacked by parasitoids continue to consume plants although they are destined to die. This peculiar property may cause parasitoids to confer a differential trophic cascading effect on plants than that known for typical predators. We hypothesized that larval koinobiont parasitoids would confer an immediate negative effect on plant seed production by stimulating consumption of their seed-predator hosts. We tested this hypothesis in an alpine parasitic food chain of plant seeds, pre-dispersal seed predators (tephritid fly larvae) and koinobiont parasitoids using field observations, a field experiment and a microcosm study. We first compared observed seed production in (i) non-infected capitula, (ii) capitula infected only by seed predators (tephritid flies) and (iii) capitula infected by both seed predators and their parasitoids in five Asteraceae species. Consistent with our hypothesis, seed loss in the capitula with both seed predators and parasitoids was significantly greater than in the capitula infested only by seed predators. This effect was replicated in a controlled field experiment focusing on the most common parasitoid-seed predator-plant interaction chain in our system, in which confounding factors (e.g. density and phenology) were excluded. Here, we show that parasitoids indirectly decreased plant seed production by changing the behaviour of seed predators. In a microcosm study, we show that larval parasitoids significantly extended the growth period and increased the terminal size of their host tephritid maggots. Thus, parasitoids suppressed plant seed production by stimulating the growth and consumption of the fly maggots. In contrast to the typical predator-induced trophic cascade, we highlight the significance of parasitoids indirectly decreasing plant fitness by stimulating consumption by seed predators

  3. Parasitoid wasps indirectly suppress seed production by stimulating consumption rates of their seed-feeding hosts.

    PubMed

    Xi, Xinqiang; Eisenhauer, Nico; Sun, Shucun

    2015-07-01

    In parasitoid-herbivore-plant food chains, parasitoids may be simultaneously linked with both herbivore hosts and plants, as occurs when herbivores attacked by parasitoids continue to consume plants although they are destined to die. This peculiar property may cause parasitoids to confer a differential trophic cascading effect on plants than that known for typical predators. We hypothesized that larval koinobiont parasitoids would confer an immediate negative effect on plant seed production by stimulating consumption of their seed-predator hosts. We tested this hypothesis in an alpine parasitic food chain of plant seeds, pre-dispersal seed predators (tephritid fly larvae) and koinobiont parasitoids using field observations, a field experiment and a microcosm study. We first compared observed seed production in (i) non-infected capitula, (ii) capitula infected only by seed predators (tephritid flies) and (iii) capitula infected by both seed predators and their parasitoids in five Asteraceae species. Consistent with our hypothesis, seed loss in the capitula with both seed predators and parasitoids was significantly greater than in the capitula infested only by seed predators. This effect was replicated in a controlled field experiment focusing on the most common parasitoid-seed predator-plant interaction chain in our system, in which confounding factors (e.g. density and phenology) were excluded. Here, we show that parasitoids indirectly decreased plant seed production by changing the behaviour of seed predators. In a microcosm study, we show that larval parasitoids significantly extended the growth period and increased the terminal size of their host tephritid maggots. Thus, parasitoids suppressed plant seed production by stimulating the growth and consumption of the fly maggots. In contrast to the typical predator-induced trophic cascade, we highlight the significance of parasitoids indirectly decreasing plant fitness by stimulating consumption by seed predators

  4. Effect of glucose concentration on the rate of fructose consumption in native strains isolated from the fermentation of Agave duranguensis.

    PubMed

    Díaz-Campillo, M; Urtíz, N; Soto, O; Barrio, E; Rutiaga, M; Páez, J

    2012-12-01

    Studies on hexose consumption by Saccharomyces cerevisiae show that glucose is consumed faster than fructose when both are present (9:1 fructose to glucose) in the medium during the fermentation of Agave. The objective of this work was to select strains of S. cerevisiae that consume fructose equal to or faster than glucose at high fructose concentrations by analyzing the influence of different glucose concentrations on the fructose consumption rate. The optimal growth conditions were determined by a kinetics assay using high performance liquid chromatography (HPLC) using 50 g of glucose and 50 g of fructose per liter of synthetic medium containing peptone and yeast extract. Using the same substrate concentrations, strain ITD-00185 was shown to have a higher reaction rate for fructose over glucose. At 75 g of fructose and 25 g of glucose per liter, strain ITD-00185 had a productivity of 1.02 gL(-1) h(-1) after 40 h and a fructose rate constant of 0.071 h(-1). It was observed that glucose concentration positively influences fructose consumption when present in a 3:1 ratio of fructose to glucose. Therefore, adapted strains at high fructose concentrations could be used as an alternative to traditional fermentation processes. PMID:22886556

  5. Effect of glucose concentration on the rate of fructose consumption in native strains isolated from the fermentation of Agave duranguensis.

    PubMed

    Díaz-Campillo, M; Urtíz, N; Soto, O; Barrio, E; Rutiaga, M; Páez, J

    2012-12-01

    Studies on hexose consumption by Saccharomyces cerevisiae show that glucose is consumed faster than fructose when both are present (9:1 fructose to glucose) in the medium during the fermentation of Agave. The objective of this work was to select strains of S. cerevisiae that consume fructose equal to or faster than glucose at high fructose concentrations by analyzing the influence of different glucose concentrations on the fructose consumption rate. The optimal growth conditions were determined by a kinetics assay using high performance liquid chromatography (HPLC) using 50 g of glucose and 50 g of fructose per liter of synthetic medium containing peptone and yeast extract. Using the same substrate concentrations, strain ITD-00185 was shown to have a higher reaction rate for fructose over glucose. At 75 g of fructose and 25 g of glucose per liter, strain ITD-00185 had a productivity of 1.02 gL(-1) h(-1) after 40 h and a fructose rate constant of 0.071 h(-1). It was observed that glucose concentration positively influences fructose consumption when present in a 3:1 ratio of fructose to glucose. Therefore, adapted strains at high fructose concentrations could be used as an alternative to traditional fermentation processes.

  6. Body mass scaling of passive oxygen diffusion in endotherms and ectotherms.

    PubMed

    Gillooly, James F; Gomez, Juan Pablo; Mavrodiev, Evgeny V; Rong, Yue; McLamore, Eric S

    2016-05-10

    The area and thickness of respiratory surfaces, and the constraints they impose on passive oxygen diffusion, have been linked to differences in oxygen consumption rates and/or aerobic activity levels in vertebrates. However, it remains unclear how respiratory surfaces and associated diffusion rates vary with body mass across vertebrates, particularly in relation to the body mass scaling of oxygen consumption rates. Here we address these issues by first quantifying the body mass dependence of respiratory surface area and respiratory barrier thickness for a diversity of endotherms (birds and mammals) and ectotherms (fishes, amphibians, and reptiles). Based on these findings, we then use Fick's law to predict the body mass scaling of oxygen diffusion for each group. Finally, we compare the predicted body mass dependence of oxygen diffusion to that of oxygen consumption in endotherms and ectotherms. We find that the slopes and intercepts of the relationships describing the body mass dependence of passive oxygen diffusion in these two groups are statistically indistinguishable from those describing the body mass dependence of oxygen consumption. Thus, the area and thickness of respiratory surfaces combine to match oxygen diffusion capacity to oxygen consumption rates in both air- and water-breathing vertebrates. In particular, the substantially lower oxygen consumption rates of ectotherms of a given body mass relative to those of endotherms correspond to differences in oxygen diffusion capacity. These results provide insights into the long-standing effort to understand the structural attributes of organisms that underlie the body mass scaling of oxygen consumption.

  7. Body mass scaling of passive oxygen diffusion in endotherms and ectotherms.

    PubMed

    Gillooly, James F; Gomez, Juan Pablo; Mavrodiev, Evgeny V; Rong, Yue; McLamore, Eric S

    2016-05-10

    The area and thickness of respiratory surfaces, and the constraints they impose on passive oxygen diffusion, have been linked to differences in oxygen consumption rates and/or aerobic activity levels in vertebrates. However, it remains unclear how respiratory surfaces and associated diffusion rates vary with body mass across vertebrates, particularly in relation to the body mass scaling of oxygen consumption rates. Here we address these issues by first quantifying the body mass dependence of respiratory surface area and respiratory barrier thickness for a diversity of endotherms (birds and mammals) and ectotherms (fishes, amphibians, and reptiles). Based on these findings, we then use Fick's law to predict the body mass scaling of oxygen diffusion for each group. Finally, we compare the predicted body mass dependence of oxygen diffusion to that of oxygen consumption in endotherms and ectotherms. We find that the slopes and intercepts of the relationships describing the body mass dependence of passive oxygen diffusion in these two groups are statistically indistinguishable from those describing the body mass dependence of oxygen consumption. Thus, the area and thickness of respiratory surfaces combine to match oxygen diffusion capacity to oxygen consumption rates in both air- and water-breathing vertebrates. In particular, the substantially lower oxygen consumption rates of ectotherms of a given body mass relative to those of endotherms correspond to differences in oxygen diffusion capacity. These results provide insights into the long-standing effort to understand the structural attributes of organisms that underlie the body mass scaling of oxygen consumption. PMID:27118837

  8. Oxygen consumption during functional electrical stimulation-assisted exercise in persons with spinal cord injury: implications for fitness and health.

    PubMed

    Hettinga, Dries M; Andrews, Brian J

    2008-01-01

    A lesion in the spinal cord leads in most cases to a significant reduction in active muscle mass, whereby the paralysed muscles cannot contribute to oxygen consumption (VO2) during exercise. Consequently, persons with spinal cord injury (SCI) can only achieve high VO2 values by excessively stressing the upper body musculature, which might increase the risk of musculoskeletal overuse injury. Alternatively, the muscle mass involved may be increased by using functional electrical stimulation (FES). FES-assisted cycling, FES-cycling combined with arm cranking (FES-hybrid exercise) and FES-rowing have all been suggested as candidates for cardiovascular training in SCI. In this article, we review the levels of VO2 (peak [VO2peak] and sub-peak [VO2sub-peak]) that have been reported for SCI subjects using these FES exercise modalities. A systematic literature search in MEDLINE, EMBASE, AMED, CINAHL, SportDiscus and the authors' own files revealed 35 studies that reported on 499 observations of VO2 levels achieved during FES-exercise in SCI. The results show that VO2peak during FES-rowing (1.98 L/min, n = 17; 24.1 mL/kg/min, n = 11) and FES-hybrid exercise (1.78 L/min, n = 67; 26.5 mL/kg/min, n = 35) is considerably higher than during FES-cycling (1.05 L/min, n = 264; 14.3 mL/kg/min, n = 171). VO2sub-peak values during FES-hybrid exercise were higher than during FES-cycling. FES-exercise training can produce large increases in VO2peak; the included studies report average increases of +11% after FES-rowing training, +12% after FES-hybrid exercise training and +28% after FES-cycling training. This review shows that VO2 during FES-rowing or FES-hybrid exercise is considerably higher than during FES-cycling. These observations are confirmed by a limited number of direct comparisons; larger studies to test the differences in effectiveness of the various types of FES-exercise as cardiovascular exercise are needed. The results to date suggest that FES-rowing and FES-hybrid are

  9. Design a Wearable Device for Blood Oxygen Concentration and Temporal Heart Beat Rate

    NASA Astrophysics Data System (ADS)

    Myint, Cho Zin; Barsoum, Nader; Ing, Wong Kiing

    2010-06-01

    The wireless network technology is increasingly important in healthcare as a result of the aging population and the tendency to acquire chronic disease such as heart attack, high blood pressure amongst the elderly. A wireless sensor network system that has the capability to monitor physiological sign such as SpO2 (Saturation of Arterial Oxygen) and heart beat rate in real-time from the human's body is highlighted in this study. This research is to design a prototype sensor network hardware, which consists of microcontroller PIC18F series and transceiver unit. The sensor is corporate into a wearable body sensor network which is small in size and easy to use. The sensor allows a non invasive, real time method to provide information regarding the health of the body. This enables a more efficient and economical means for managing the health care of the population.

  10. Reaction of singlet oxygen with tryptophan in proteins: a pronounced effect of the local environment on the reaction rate.

    PubMed

    Jensen, Rasmus Lybech; Arnbjerg, Jacob; Ogilby, Peter R

    2012-06-13

    Singlet molecular oxygen, O(2)(a(1)Δ(g)), can influence many processes pertinent to the function of biological systems, including events that result in cell death. Many of these processes involve a reaction between singlet oxygen and a given amino acid in a protein. As a result, the behavior of that protein can change, either because of a structural alteration and/or a direct modification of an active site. Surprisingly, however, little is known about rate constants for reactions between singlet oxygen and amino acids when the latter are in a protein. In this report, we demonstrate using five separate proteins, each containing only a single tryptophan residue, that the rate constant for singlet oxygen reaction with tryptophan depends significantly on the position of this amino acid in the protein. Most importantly, the reaction rate constant depends not only on the accessibility of the tryptophan residue to oxygen, but also on factors that characterize the local molecular environment of the tryptophan in the protein. The fact that the local protein environment can either appreciably inhibit or accelerate the reaction of singlet oxygen with a given amino acid can have significant ramifications for singlet-oxygen-mediated events that perturb cell function.

  11. Oxygen supply in disposable shake-flasks: prediction of oxygen transfer rate, oxygen saturation and maximum cell concentration during aerobic growth.

    PubMed

    Schiefelbein, Sarah; Fröhlich, Alexander; John, Gernot T; Beutler, Falco; Wittmann, Christoph; Becker, Judith

    2013-08-01

    Dissolved oxygen plays an essential role in aerobic cultivation especially due to its low solubility. Under unfavorable conditions of mixing and vessel geometry it can become limiting. This, however, is difficult to predict and thus the right choice for an optimal experimental set-up is challenging. To overcome this, we developed a method which allows a robust prediction of the dissolved oxygen concentration during aerobic growth. This integrates newly established mathematical correlations for the determination of the volumetric gas-liquid mass transfer coefficient (kLa) in disposable shake-flasks from the filling volume, the vessel size and the agitation speed. Tested for the industrial production organism Corynebacterium glutamicum, this enabled a reliable design of culture conditions and allowed to predict the maximum possible cell concentration without oxygen limitation.

  12. Oxygen supply in disposable shake-flasks: prediction of oxygen transfer rate, oxygen saturation and maximum cell concentration during aerobic growth.

    PubMed

    Schiefelbein, Sarah; Fröhlich, Alexander; John, Gernot T; Beutler, Falco; Wittmann, Christoph; Becker, Judith

    2013-08-01

    Dissolved oxygen plays an essential role in aerobic cultivation especially due to its low solubility. Under unfavorable conditions of mixing and vessel geometry it can become limiting. This, however, is difficult to predict and thus the right choice for an optimal experimental set-up is challenging. To overcome this, we developed a method which allows a robust prediction of the dissolved oxygen concentration during aerobic growth. This integrates newly established mathematical correlations for the determination of the volumetric gas-liquid mass transfer coefficient (kLa) in disposable shake-flasks from the filling volume, the vessel size and the agitation speed. Tested for the industrial production organism Corynebacterium glutamicum, this enabled a reliable design of culture conditions and allowed to predict the maximum possible cell concentration without oxygen limitation. PMID:23592306

  13. Reduced Fetal Cerebral Oxygen Consumption is Associated With Smaller Brain Size in Fetuses With Congenital Heart Disease

    PubMed Central

    Sun, Liqun; Macgowan, Christopher K; Sled, John G; Yoo, Shi-Joon; Manlhiot, Cedric; Porayette, Prashob; Grosse-Wortmann, Lars; Jaeggi, Edgar; McCrindle, Brian W; Kingdom, John; Hickey, Edward; Miller, Steven; Seed, Mike

    2015-01-01

    Background Fetal hypoxia has been implicated in the abnormal brain development seen in newborns with congenital heart disease (CHD). New magnetic resonance imaging (MRI) technology now offers the potential to investigate the relationship between fetal hemodynamics and brain dysmaturation. Methods and Results We measured fetal brain size, oxygen saturation and blood flow in the major vessels of the fetal circulation in 30 late gestation fetuses with CHD and 30 normal controls using phase contrast MRI and T2 mapping. Fetal hemodynamic parameters were calculated using a combination of MRI flow and oximetry data and fetal hemoglobin concentrations estimated from population averages. In fetuses with CHD, reductions in umbilical vein oxygen content (p<0.001), and failure of the normal streaming of oxygenated blood from the placenta to the ascending aorta were associated with a mean reduction in ascending aortic saturation of 10% (p < 0.001), while cerebral blood flow and cerebral oxygen extraction were no different from controls. This accounted for the mean 15% reduction in cerebral oxygen delivery (p = 0.08) and 32% reduction cerebral VO2 in CHD fetuses (p < 0.001), which were associated with a 13% reduction in fetal brain volume (p < 0.001). Fetal brain size correlated with ascending aortic oxygen saturation and cerebral VO2 (r = 0.37 p = 0.004). Conclusions This study supports a direct link between reduced cerebral oxygenation and impaired brain growth in fetuses with CHD and raises the possibility that in utero brain development could be improved with maternal oxygen therapy. PMID:25762062

  14. 15O PET Measurement of Blood Flow and Oxygen Consumption in Cold-Activated Human Brown Fat

    PubMed Central

    Muzik, Otto; Mangner, Thomas J.; Leonard, William R.; Kumar, Ajay; Janisse, James; Granneman, James G.

    2013-01-01

    Although it has been believed that brown adipose tissue (BAT) depots disappear shortly after the perinatal period in humans, PET imaging using the glucose analog 18F-FDG has shown unequivocally the existence of functional BAT in adult humans, suggesting that many humans retain some functional BAT past infancy. The objective of this study was to determine to what extent BAT thermogenesis is activated in adults during cold stress and to establish the relationship between BAT oxidative metabolism and 18F-FDG tracer uptake. Methods Twenty-five healthy adults (15 women and 10 men; mean age ± SD, 30 ± 7 y) underwent triple-oxygen scans (H215O, C15O, and 15O2) as well as measurements of daily energy expenditure (DEE; kcal/d) both at rest and after exposure to mild cold (15.5°C [60°F]) using indirect calorimetry. The subjects were divided into 2 groups (high BAT and low BAT) based on the presence or absence of 18F-FDG tracer uptake (standardized uptake value [SUV] > 2) in cervical–supraclavicular BAT. Blood flow and oxygen extraction fraction (OEF) were calculated from dynamic PET scans at the location of BAT, muscle, and white adipose tissue. Regional blood oxygen saturation was determined by near-infrared spectroscopy. The total energy expenditure during rest and mild cold stress was measured by indirect calorimetry. Tissue-level metabolic rate of oxygen (MRO2) in BAT was determined and used to calculate the contribution of activated BAT to DEE. Results The mass of activated BAT was 59.1 ± 17.5 g (range, 32–85 g) in the high-BAT group (8 women and 1 man; mean age, 29.6 ± 5.5 y) and 2.2 ± 3.6 g (range, 0–9.3 g) in the low-BAT group (9 men and 7 women; mean age, 31.4 ± 10 y). Corresponding maximal SUVs were significantly higher in the high-BAT group than in the low-BAT group (10.7 ± 3.9 vs. 2.1 ± 0.7, P = 0.01). Blood flow values were significantly higher in the high-BAT group than in the low-BAT group for BAT (12.9 ± 4.1 vs. 5.9 ± 2.2 mL/100 g/min, P = 0

  15. The Rate of Photorespiration as Measured by Means of Oxygen Uptake and Its Respiratory Quotient

    PubMed Central

    Samish, Yochai B.

    1971-01-01

    Oxygen recycling inside photosynthesizing leaves was found to amount to less than 0.3% of the oxygen consumed by photorespiration under natural conditions, provided the influence of buildup of oxygen released by photosynthesis into the external air was taken into consideration. When this is related to the amounts of photorespired CO2, which had been previously found to be reabsorbed by photosynthesis, it appears that previous respiratory quotients reported for photorespiration were underestimated. For the same reason the photosynthetic quotient was overestimated. Actually, quotients of photorespiration and of photosynthesis approach the more normal range of respiratory quotients int the dark. The oxygen recycling was calculated according to an electrical analogue to oxygen flow. The determination of photorespiration, when measured by oxygen uptake, can be more accurate than that by CO2 measurement. However, recycling of oxygen occurs in larger amounts at lower oxygen and higher CO2 concentrations, as well as under conditions of high resistance to transpiration. PMID:16657795

  16. Low effective activation energies for oxygen release from metal oxides: evidence for mass-transfer limits at high heating rates.

    PubMed

    Jian, Guoqiang; Zhou, Lei; Piekiel, Nicholas W; Zachariah, Michael R

    2014-06-01

    Oxygen release from metal oxides at high temperatures is relevant to many thermally activated chemical processes, including chemical-looping combustion, solar thermochemical cycles and energetic thermite reactions. In this study, we evaluated the thermal decomposition of nanosized metal oxides under rapid heating (~10(5) K s(-1)) with time-resolved mass spectrometry. We found that the effective activation-energy values that were obtained using the Flynn-Wall-Ozawa isoconversional method are much lower than the values found at low heating rates, indicating that oxygen transport might be rate-determining at a high heating rate.

  17. Changes in heart rate variability associated with acute alcohol consumption: current knowledge and implications for practice and research.

    PubMed

    Romanowicz, Magdalena; Schmidt, John E; Bostwick, John M; Mrazek, David A; Karpyak, Victor M

    2011-06-01

    Alcohol consumption is associated with a broad array of physiologic and behavioral effects including changes in heart rate. However, the physiologic mechanisms of alcohol effects and the reasons for individual differences in the cardiac response remain unknown. Measuring changes in resting heart rate (measured as beats/min) has not been found to be as sensitive to alcohol's effects as changes in heart rate variability (HRV). HRV is defined as fluctuations in interbeat interval length which reflect the heart's response to extracardiac factors that affect heart rate. HRV allows simultaneous assessment of both sympathetic and parasympathetic activity and the interplay between them. Increased HRV has been associated with exercise and aerobic fitness, while decreased HRV has been associated with aging, chronic stress, and a wide variety of medical and psychiatric disorders. Decreased HRV has predictive value for mortality in general population samples and patients with myocardial infarction and used as an indicator of altered autonomic function. A significant inverse correlation was found between HRV and both the severity of depression and the duration of the depressive episode. HRV analysis provides insights into mechanisms of autonomic regulation and i